Abstract

We studied the acceptability of isoniazid preventive therapy (IPT) in newly human immunodeficiency virus (HIV) infected Ugandan women. Women were followed in an out-patient clinic where they received HIV care including IPT. Of 52 women who were purified protein derivative-positive, 48 were eligible for IPT and 39 (81%) completed therapy. This completion rate was higher than reported in similar observational studies.

To evaluate utility of C-reactive protein (CRP) in the early diagnosis of neonatal sepsis in a tertiary care Newborn Unit in Kenya. DESIGN: Cross-sectional study. SETTING: Newborn Unit, Kenyatta National Hospital. SUBJECTS: All neonates admitted to Newborn Unit, Kenyatta National Hospital during the study period with suspected sepsis based on specified clinical criteria. RESULTS: Of the 310 infants, there were 83 episodes of proven sepsis and 94 episodes of probable sepsis. Using the standard CRP cut-off value of 5 mg/dl, a sensitivity of 95.2% in proven sepsis and 98.9% for probable septic episodes were noted. In proven sepsis, a specificity of 85.3%, positive predictive value of 80.6%, and a negative predictive value of 96.5% were noted. In probable sepsis, a specificity of 83.3%, positive predictive value of 80.9% and a negative predictive value of 99.1% were noted. The overall accuracy in proven sepsis was 96.5%, and in probable sepsis was noted to be 99.1%. Sub-analysis showed a lower positive predictive value (61.5%) for early onset sepsis compared to 93% for late onset sepsis. Repeat CRP tests were done in 33 babies. Twenty two of the 29 with proven/probable infection had a ten-fold increase in CRP levels, but levels were noted to be low or reducing in seven (24.1%) babies showing signs of improvement clinically. Using a receiver operator characteristic curve, the optimal cut-off point for CRP was found to be 5 mg/dl. CONCLUSIONS: Serum CRP is an accurate indicator of neonatal sepsis, with high sensitivity, specificity and predictive values, at the standard cut-off of 5. CRP is a better screening test for late-onset than early-onset neonatal sepsis. The standard recommended CRP cut -off point of 5 is appropriate for local use

Abstract
Human rotaviruses have emerged as a leading cause of acute diarrhea in children <5 years of age worldwide. Although there are previous reports relating to various aspects of rotaviruses, there is limited data on the involvement of rotavirus infection in HIV-infected children. We therefore evaluated the importance of rotavirus infections in HIV-related diarrhea in Kenyan children. Fecal samples were collected from a total of 207 children during the period February 1999 to June 2000 and screened for HRV antigen by enzyme-linked immunosorbent assay (ELISA). Positive samples were analyzed by VP6 subgroup specificity assay, by polyacrylamide gel electrophoresis (PAGE) and reverse transcriptase/polymerase chain reaction (RT-PCR). Fourteen percent (29/207) of the samples were positive. HIV-seropositive children with diarrhea were more likely than their counterparts without diarrhea to have rotaviruses [23.3% (10/43) versus 2.9% (2/70); p = 0.0001]. Rotavirus strain G3P[6] was predominant. These results indicate that rotavirus is an important viral etiological agent causing diarrhea in HIV-seropositive children.

PIP: In November and December, 1993, a self-administered questionnaire was distributed to men in the town of Machakos and to nonmedical hospital workers of Machakos General Hospital. The purpose of the study was to assess their knowledge about and attitude towards vasectomy. The majority of men were in the age group of 30-44 years and were married; the hospital group was more educated. The town men perceived the pill to be the best contraceptive method for women in contrast to the hospital group who gave more importance to bilateral tubal ligation. The hospital group also perceived vasectomy as the best method for men. Overall, 53.2% men were aware of the correct procedure of vasectomy, but only 24% had correct knowledge of how the procedure affects masculinity. The knowledge of the procedure among hospital workers was not very different from that of the town group. Recommendations were made to increase information and education to all groups of people through various media. author's modified

No abstract available.

n/a

Meningitis occurs in up to one third of neonates with septicaemia. Diagnosis is difficult due to its non-specificity of signs and symptoms. While neonatal septicaemia is a common problem at Kenyatta National Hospital (KNH), there are no recent data on the incidence and clinical characteristics of neonatal meningitis at the hospital.

{ BACKGROUND: Meningitis occurs in up to one third of neonates with septicaemia. Diagnosis is difficult due to its non-specificity of signs and symptoms. While neonatal septicaemia is a common problem at Kenyatta National Hospital (KNH), there are no recent data on the incidence and clinical characteristics of neonatal meningitis at the hospital. OBJECTIVE: To evaluate the prevalence and the bacterial aetiology of meningitis in neonates at the Newborn Unit (NBU) of KNH. DESIGN: Descriptive cross-sectional study. SETTING: Newborn Unit of Kenyatta National Hospital, Nairobi, Kenya. SUBJECTS AND METHODS: Lumbar punctures were performed on eighty-four neonates with suspected sepsis based on specified clinical criteria. Cases were defined as meningitis if the cerebrospinal fluid (CSF) was positive for bacteria by Gram stain, aerobic bacterial culture or latex particle agglutination assay. RESULTS: The prevalence of meningitis amongst cases of suspected sepsis was 17.9%. The male:female ratio was 1.5:1 mean birth weight 2116.7 grams (1682.2-2551.2) mean gestational age 35.7 weeks (32.6-38.8) and the mean postnatal age was 4.1 days (2.7-5.4) with none of the parameters being significantly different from those without meningitis. Feed intolerance and lethargy were the most common clinical features, present in 73.3% and 60% of patients with meningitis respectively. Neonates with meningitis had a higher mean CSF protein value (2.67 g/L vs 1.97 g/L

Infants less than 1500 grams at birth have been demonstrated to be particularly prone to development of low levels of serum sodium often leading to increased early neonatal morbidity and mortality. No local study has been done to quantify this problem among sick newborns. Studies elsewhere demonstrate a high incidence of hyponatraemia among such preterms.

Survival of patients is regularly used as a measure of the level and appropriateness of medical care provided by institutions. Newborn services have been evaluated in this manner since the 1960s. Though Kenyatta National Hospital has provided neonatal services for over 25 years, no survival data for the low birth weight infants has been published since 1978.

Sodium and potassium levels were measured weekly in mothers' milk and in serum and urine of 41 supplemented and 25 unsupplemented very-low-birth-weight infants whose mean birth weights were 1390g and 1332g, respectively (mean gestational age, 31 weeks). Sodium intake was 5.95mmol/kg/day for the supplemented group and 2.75mmol/kg/day for controls. None of the infants in either group was hyponatremic during the 6-week period of study. Urinary sodium in the supplemented group was 15.7mmol/L as compared with 7.5mmol/L in controls. Human milk sodium was significantly lower than reported elsewhere. Growth in the supplemented group was greater than in the unsupplemented group. Since no episode of hyponatremia occurred, it was concluded that routine sodium supplementation was unnecessary.

Department of Paediatrics, University of Nairobi, Kenya. Sodium and potassium levels were measured weekly in mothers' milk and in serum and urine of 41 supplemented and 25 unsupplemented very-low-birth-weight infants whose mean birth weights were 1390g and 1332g, respectively (mean gestational age, 31 weeks). Sodium intake was 5.95mmol/kg/day for the supplemented group and 2.75mmol/kg/day for controls. None of the infants in either group was hyponatremic during the 6-week period of study. Urinary sodium in the supplemented group was 15.7mmol/L as compared with 7.5mmol/L in controls. Human milk sodium was significantly lower than reported elsewhere. Growth in the supplemented group was greater than in the unsupplemented group. Since no episode of hyponatremia occurred, it was concluded that routine sodium supplementation was unnecessary. PMID: 11787713 [PubMed - indexed for MEDLINE]

Department of Paediatrics, University of Nairobi, Kenya. Multidrug-resistant organisms are increasing worldwide. Over the years we have noted increasing resistance of organisms isolated in our neonatal unit. There is a need therefore to scrutinize the problem so as to be able to plan for the future. Over a 5-month period, 716 infants were admitted of which 192 were screened for sepsis. Overall, 121 (16.7 per cent) had positive blood cultures. The predominant organisms were Gram negative (73.6 per cent of isolates) with Klebsiella species topping the list at 31 per cent. Case fatality for infants infected with Gram negative organisms was 41 per cent. Resistance to gentamicin was 20 per cent chloramphenicol 23.6 per cent, and amoxicillin/ampicillin 66.3 per cent. Of worry is the resistance to ceftazidime 19.1 per cent, and cefuroxime 21.3 per cent, with the figures rising to 27 per cent when more specialized tests are done (disc approximation and potentiation tests). If these drugs cannot be used in 20-27 per cent of cases then the situation is serious. The contributory factors to increased resistance include: non-investigation of infants put on antibiotics (50 per cent of cases); prolonged (73 per cent) and sometimes unjustified (41.7 per cent) use of antibiotics; and non-utilization of investigations when these are done (52 per cent) together with the delay in getting results back in the ward (6 days). PMID: 10822934 [PubMed - indexed for MEDLINE]

Reports of osteopaenia/rickets of prematurity are on the increase due to improved survival rates of low birthweight infants.

To determine the knowledge, attitudes and practices (KAP) of mothers and the knowledge of health workers regarding care of the newborn umbilical cord.

OBJECTIVE: To determine the pattern of growth and development of institutionalised infants and to compare the outcome with that of infants living with their biological mothers. DESIGN: A cross-sectional survey. SETTING: Seven children's homes; Kenyatta National Hospital's New Born Unit and Well Baby Clinics in Nairobi, Kenya. PARTICIPANTS: Eighty-two abandoned babies who fulfilled the selection criteria were recruited and for each abandoned baby two mothered babies matched for age and sex were selected from the well baby clinics. MAIN OUTCOME MEASURES: Anthropometric measures of weight, length, head circumference and left mid arm circumference (LUMAC) were taken and the mean values and Z scores determined to demonstrate growth pattern and nutritional status of the babies. The Revised Denver Development Screening Test (RDDST) was used to assess the development pattern of infants. RESULTS: Seventy per cent of infants were below six months old and 73% were abandoned within the first week of life. Abandoned babies were significantly thinner with the mean LUMAC of 10.8 cm versus 12.3 cm (p = 0.02) Institutionalised babies were significantly wasted (p = 0.00001) and stunted (p = 0.00001). Abandoned babies were significantly delayed in development (p < 0.0001). In all the four sectors tested for, institutionalised babies showed significant delay, p < 0.0001 in each sector. CONCLUSION: This study demonstrates that infants under institutional care have poorer growth and development compared to mothered infants. PIP: This cross-sectional study examined the pattern of growth and development of infants in some of the baby institutions in Nairobi and compared the outcome with that of infants living with their biological mothers. The participating institutions included the Kenyatta National Hospital and 7 children's homes within the city. The study recruited 82 abandoned babies aged 1-18 months who had been abandoned for at least 2 weeks. Each abandoned baby was paired with 2 mothered babies matched for age and sex. Anthropometric measures of weight, length, head circumference, and left mid arm circumference (LUMAC) were taken. The mean values and Z scores were determined to assess growth pattern and nutritional status of the babies. The results showed that abandoned babies were significantly thinner, with a mean LUMAC of 10.8 cm vs. 12.3 cm. Moreover, abandoned babies were significantly wasted (p = 0.00001), stunted (p = 0.00001), and delayed in development (p 0.0001). These findings indicate that institutionalized infants have poorer growth and development compared to mothered infants.

BACKGROUND: Reports of osteopaenia/rickets of prematurity are on the increase due to improved survival rates of low birthweight infants. OBJECTIVE: To establish the incidence of rickets of prematurity by the age of six months in premature infants born at Kenyatta National Hospital, Nairobi. DESIGN: Prospective cohort study. SETTING: Newborn unit and paediatric outpatient follow up clinic of Kenyatta National Hospital. SUBJECTS: Successive surviving infants of birthweight less than 2000 g residents in Nairobi. RESULTS: Incidence of rickets of prematurity by six months of age was 58.8%. Rickets appeared more commonly in male infants compared to female infants. CONCLUSION: Rickets of prematurity is a common problem in the premature infants seen at Kenyatta National Hospital. Routine vitamin D supplements to premature infants in adequate doses of at least 400iu per day should be adopted in our centre.

Department of Paediatrics and Child Health, College of Health Sciences, University of Nairobi. OBJECTIVE: To determine the knowledge, attitudes and practices (KAP) of mothers and the knowledge of health workers regarding care of the newborn umbilical cord. DESIGN: Cross-sectional survey. SUBJECTS: Mothers with infants less than three months of age attending well child clinics and health workers (HW) in the clinics, maternity and newborn units of public health, facilities serving an urban slum area in Nairobi, Kenya. RESULTS: Of the 307 mothers interviewed, 91% and 28% of mothers knew of the need for hygiene whilst cutting and tying the cord, respectively. Regarding postnatal cord care, 40% had good knowledge and 66% good practice. Fifty-one percent of mothers knew and 54% practised postnatal cord care for the appropriate duration of time. Seventy-nine percent of mothers were afraid of handling an unhealed cord. After multivariate analysis, the following variables showed significant independent association with good maternal KAP; increased level of education (OR 2.3, p < 0.001), living in middle class areas rather than slums (OR 1.5, p < 0.03), increased maternal age (OR 1.8, p < 0.001), acquisition of knowledge from a HW rather than from other sources (OR 1.5, p < 0.001), and living in stone/brick houses rather than mud houses (p = 0.01). Fifty per cent of HW had correct knowledge on type of postnatal cord care, and 79% had correct knowledge on duration required for the same. The knowledge of 50% on type of care was incorrect by international standards, but was in keeping with Nursing Council of Kenya teaching. CONCLUSION: Mothers had good knowledge on the need for hygiene when cutting the cord, had poor knowledge and practice in other aspects of cord care, and were afraid of handling the cord. Poor KAP was associated with young, poor mothers of low education, who had acquired their knowledge from sources other than HW. The knowledge of a large proportion of HW was incorrect and outdated. We recommend that health education on cord care be given at all levels of contact with mothers and that knowledge of all primary HW on cord care be updated. PIP: Using a cross-sectional survey, this study investigated the knowledge, attitudes, and practices (KAP) of mothers and the knowledge of health workers regarding care of the umbilical cord. The study interviewed a total of 307 mothers with infants less than 3 months old and 64 health workers (HWs) in an urban slum area in Nairobi, Kenya. The results showed that 91% and 28% of mothers knew of the need for hygiene while cutting and tying the cord, respectively. As to postnatal cord care, 40% had good knowledge and 66% had good practice. However, 79% of mothers were afraid of handling an unhealed cord. Results of multivariate analysis showed that the following variables had significant independent association with good maternal KAP: increased level of education, living in middle class areas, increased maternal age, and acquisition of knowledge from HWs rather than from other sources. 50% of HWs had correct knowledge on type of postnatal cord care, but the knowledge of 50% on type of care was incorrect by international standards. Based on the findings, it was recommended that good health and cord care practices be taught at all levels of contact with mothers and that knowledge of all primary HWs on cord care be updated.

Review of the management of neonatal infections is done with the aim of guiding the clinician on appropriate therapy. Minimum investigations should include a white blood cell count including the L:T ratio and a blood culture. The bulk of infections at Kenyatta National Hospital newborn unit are caused by Klebsiela, Citrobacter and Staphylococcus aureus. During the 1990's considerable resistance to gentamicin has developed. Currently, cephalosporins chloramphenicol have the best sensitivity pattern. The diagnosis must be carefully verified at different stages of treatment to ensure that only those requiring antimicrobial therapy get it. Indiscriminate use is thus avoided. This in turn minimises development of antibiotic resistant organisms. Failure of response to antimicrobials sometimes means a non infectious cause of illness or poor supportive management. Continuous surveillance is recommended with emphasis on primary prevention of infection as well as cross infections.

Eighteen abandoned low birth weight infants matched for sex and gestational age with infants who had mothers were followed up till discharge or death. Anthropometric measurements were taken on recruitment and then weekly. Initially all infants were on breast milk. For the abandoned ones, milk was obtained from other mothers. Results show that the abandoned infants were on breast milk until they attained a mean weight of 1960gm. This coincided with a postnatal age of 6 weeks. For the rest of the period they were on artificial feed. Mean birth weight was 1403 +/- 302 and 1337 +/- 204 for cases and controls respectively while the mean gestation was 30 weeks. Anthropometric measurements were similar at the beginning of the study and both groups regained birth weight at 2 weeks. Thereafter the rate of weight gain of 16gm per day for the cases was significantly lower than that of 22gm per day for the controls. Similarly midarm circumference increases were much lower in the cases than in controls (0.2cm versus 0.4 per week). There were however no significant differences in length and head circumference increases. A significant number of cases (94.4%) had one or more episodes of serious infection and 38.9% died. None of the control infants died and only 10.5% had serious infection.

Sodium supplementation was done on 41 very low birth weight (VLBW) preterm infants with 25 other infants of similar weight status as controls. All the infants were fed on their own mothers milk whose sodium and potassium content was determined. Serum and urinary sodium, potassium and creatinine levels were determined in both groups during the study period of six weeks. Determination of weight gain, length gain and head circumference gain showed that these anthropometric parameters are significantly increased by sodium supplementation while sodium and potassium concentrations were not significantly affected. There were no cases of either hypernatraemia or hyponatraemia though renal excretion of sodium was very high in the supplemented group. Conclusions drawn from the study are that very little weight gain could have been due to fluid retention and that though sodium supplementation does not affect sodium profiles in these infants it has significant effect on their growth rate which may be due to its indirect/direct association with bone and protein metabolism.

To determine whether the "Baby Cloche" heat shield improves temperature control in low birth-weight infants we compared serial temperatures in 11 preterm infants nursed with or without the Cloche. Mean birth weights were 1490 and 1510 gm, mean weights at time of study 1680 and 1710 gm and mean postnatal age 20 and 27 days for study and control infants respectively. Serial measurements of rectal, abdominal skin, dorsum of the foot, Cloche wall and room temperature were recorded once or twice daily for 2 to 5 days. Mean rectal temperatures increased with increasing age from 35.3 in the first week of life to 37.0 degrees C by the third week (P less than 0.001). In infants nursed under the Cloche who were over 2 weeks of age mean rectal, abdominal and foot temperatures were 0.5, 0.6 and 1.6 degrees C higher (P less than 0.001); in younger infants there was no significant difference in any of the temperatures. Our findings suggest that the "Baby Cloche" improves temperature control in preterm infants over 1600 gm who are more than 2 weeks of age.

Department of Paediatrics, University of Nairobi. To determine whether the "Baby Cloche" heat shield improves temperature control in low birth-weight infants we compared serial temperatures in 11 preterm infants nursed with or without the Cloche. Mean birth weights were 1490 and 1510 gm, mean weights at time of study 1680 and 1710 gm and mean postnatal age 20 and 27 days for study and control infants respectively. Serial measurements of rectal, abdominal skin, dorsum of the foot, Cloche wall and room temperature were recorded once or twice daily for 2 to 5 days. Mean rectal temperatures increased with increasing age from 35.3 in the first week of life to 37.0 degrees C by the third week (P less than 0.001). In infants nursed under the Cloche who were over 2 weeks of age mean rectal, abdominal and foot temperatures were 0.5, 0.6 and 1.6 degrees C higher (P less than 0.001); in younger infants there was no significant difference in any of the temperatures. Our findings suggest that the "Baby Cloche" improves temperature control in preterm infants over 1600 gm who are more than 2 weeks of age. PMID: 1628548 [PubMed - indexed for MEDLINE]

Department of Paediatrics, College of Health Sciences, University of Nairobi, Kenya. Sodium supplementation was done on 41 very low birth weight (VLBW) preterm infants with 25 other infants of similar weight status as controls. All the infants were fed on their own mothers milk whose sodium and potassium content was determined. Serum and urinary sodium, potassium and creatinine levels were determined in both groups during the study period of six weeks. Determination of weight gain, length gain and head circumference gain showed that these anthropometric parameters are significantly increased by sodium supplementation while sodium and potassium concentrations were not significantly affected. There were no cases of either hypernatraemia or hyponatraemia though renal excretion of sodium was very high in the supplemented group. Conclusions drawn from the study are that very little weight gain could have been due to fluid retention and that though sodium supplementation does not affect sodium profiles in these infants it has significant effect on their growth rate which may be due to its indirect/direct association with bone and protein metabolism. PMID: 1473517 [PubMed - indexed for MEDLINE]

During a 7 month period, April to October, 1984, 537 consecutive babies weighing upto 2000 gm were studied at the Kenyatta National Hospital's newborn unit. Of these 48 (8.9%) had murmurs suggestive of patent ductus arteriosus (PDA). Their mean birth weight was 1364 +/- 482 gm while the mean gestation was 30.5 weeks. The peak incidence occurred in the weight group 1001 to 1500 gm. 15 (31%) of all infants with PDA died. The PDA closed spontaneously in 21 (43.7%) infants before discharge from hospital and 4 closed after discharge bringing the total closure of 25 (52%). This represented 76% of the survivors. 4 were lost to follow up. In another 4 infants there was inadequate information as to when the ductus closed. It is suggested that the relatively low incidence of PDA may be due to underdiagnosis and the high mortality infants less than 1000 gm in the first few days of life before diagnosis of PDA can be made. Wider use of objective diagnostic modalities may help to make definitive diagnosis.

Department of Paediatrics, College of Health Sciences, University of Nairobi, Kenya.

During a 7 month period, April to October, 1984, 537 consecutive babies weighing upto 2000 gm were studied at the Kenyatta National Hospital's newborn unit. Of these 48 (8.9%) had murmurs suggestive of patent ductus arteriosus (PDA). Their mean birth weight was 1364 +/- 482 gm while the mean gestation was 30.5 weeks. The peak incidence occurred in the weight group 1001 to 1500 gm. 15 (31%) of all infants with PDA died. The PDA closed spontaneously in 21 (43.7%) infants before discharge from hospital and 4 closed after discharge bringing the total closure of 25 (52%). This represented 76% of the survivors. 4 were lost to follow up. In another 4 infants there was inadequate information as to when the ductus closed. It is suggested that the relatively low incidence of PDA may be due to underdiagnosis and the high mortality infants less than 1000 gm in the first few days of life before diagnosis of PDA can be made. Wider use of objective diagnostic modalities may help to make definitive diagnosis.

PIP: During a 7 month period, April-October 1984, 537 consecutive babies weighing up to 2000 gm were studied at the Kenyatta National Hospital's newborn unit. Of these, 48 (8.9%) had murmurs suggestive of patent ductus arteriosus (PDA). Their mean birth weight was 1364 +or- 482 gm while the mean gestation was 30.5 weeks. The peak incidence occurred in the weight group 1001-1500 gm. 15 (31%) of all infants with PDA died. The PDA closed spontaneously in 21 (43.7%) infants prior to discharge from the hospital and 4 closed after discharge bringing the total closure of 25 (52%). This represented 76% of the survivors. 4 were lost to follow up. In the cases of 4 other infants, there was inadequate information as to when the ductus closed. It is suggested that the relatively low incidence of PDA may be due to underdiagnosis and the high mortality infant 1000 gm in the 1st few days of life prior to when the diagnosis of PDA can be made. Wider use of objective diagnostic modalities may help to make a definitive diagnosis. author's modified

PMID: 1765017 [PubMed - indexed for MEDLINE]

Though there is still some reluctance to use human milk for low birth weight infants, we have shown that it is possible exclusively to feed these infants on milk from their own mothers. The infants have adequate weight gain and are less likely to get infections, especially gastrointestinal and respiratory. It is possible to sustain lactation through manual expression during the period that the mother is not nursing her infant directly on the breast. A cup rather than a bottle can be used to feed these small infants. The mothers are thus encouraged because the infant does not suffer nipple confusion with a bottle and they continue breastfeeding after discharge from the hospital.

Department of Paediatrics, University of Nairobi, Kenya. Though there is still some reluctance to use human milk for low birth weight infants, we have shown that it is possible exclusively to feed these infants on milk from their own mothers. The infants have adequate weight gain and are less likely to get infections, especially gastrointestinal and respiratory. It is possible to sustain lactation through manual expression during the period that the mother is not nursing her infant directly on the breast. A cup rather than a bottle can be used to feed these small infants. The mothers are thus encouraged because the infant does not suffer nipple confusion with a bottle and they continue breastfeeding after discharge from the hospital. PMID: 1972088 [PubMed - indexed for MEDLINE]

The weight of 64 preterm appropriate for gestational age infants were followed closely during the period of stay in the newborn unit. They were subdivided into three groups: A (1001-1250 g), B (1250-1500 g), and C (1501-1750 g). The mean gestation for these groups were 28.7, 30.5, and 31 weeks, respectively, while mean birth weights were 1132 +/- 81.7 g, 1377 +/- 85.6 g, and 1641 +/- 88.6 g. All were fed their own mothers breast milk during the period of study with no supplements. During the first week, there was significant weight loss in all groups as follows: A (12.0 per cent), B (7.7 per cent), and C (4.4 per cent). Thereafter, only group A lost weight in the second week, but the loss was not significant. Birth weights were regained at 23, 16, and 15 days, respectively. The weight gain after the initial loss was A (20.0 g), B (20.4 g), and C (20.2 g) per day. Group A had the fastest growth rate. PMID: 2585581 [PubMed - indexed for MEDLINE]

No abstract available.

In Kenya hepatitis B virus (HBV) infection and its sequelae are common. We followed up 49 hepatitis B surface antigen (HBsAg)- positive mothers and their newborn infants for 9 months to determine the importance of perinatal transmission in the African and to relate this to the HBe and HBV-DNA status of the mother. Our study shows that perinatal transmission is relatively unimportant in Kenya and that this may be a consequence of the low levels of circulating HBV-DNA in the maternal plasma. These results imply that vaccination without hyperimmune globulin may be adequate to control HBV infection in Kenya

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Eight patients had cardiac manifestations that were life-threatening in five while taking psychotropic drugs, either phenothiazines or tricyclic antidepressants. Although most patients were receiving several drugs, Mellaril (thioridazine) appeared to be responsible for five cases of ventricular tachycardia, one of which was fatal in a 35 year old woman. Supraventricular tachycardia developed in one patient receiving Thorazine (chlorpromazine). Aventyl (nortriptyline) and Elavil (amitriptyline) each produced left bundle branch block in a 73 year old woman. Electrocardiographic T and U wave abnormalities were present in most patients. The ventricular arrhythmias responded to intravenous administration of lidocaine and to direct current electric shock; ventricular pacing was required in some instances and intravenous administration of propranolol combined with ventricular pacing in one. The tachyarrhythmias generally subsided within 48 hours after administration of the drugs was stopped. Five of the eight patients were 50 years of age or younger; only one clearly had antecedent heart disease. Major cardiac arrhythmias are a potential hazard in patients without heart disease who are receiving customary therapeutic doses of psychotropic drugs. A prospective clinical trial is suggested to quantify the risk of cardiac complications to patients receiving phenothiazines or tricyclic antidepressant drugs.

The distribution of blood flow to the subendocardial, medium and subepicardial layers of the left ventricular free wall was studied in anaesthetized dogs under normoxic (A), hypoxic (B) conditions and under pharmacologically induced (etafenone) coronary vasodilation (C). Regional myocardial blood flow was determined by means of the particle distribution method. In normoxia a transmural gradient of flow was observed, with the subendocardial layers receiving a significantly higher flow rate compared with the subepicardial layers. In hypoxia induced vasodilation this transmural gradient of flow was persistent. In contrast a marked redistribution of regional flow was observed under pharmacologically induced vasodilation. The transmural gradient decreased. In contrast to some findings these experiments demonstrate that a considerable vasodilatory capacity exists in all layers of the myocardium and can be utilized by drugs. The differences observed for the intramural distribution pattern of flow under hypoxia and drug induced vasodilation support the hypothesis that this pattern reflects corresponding gradients of regional myocardial metabolism.

Five distinct ester hydrolases (EC 3-1) have been characterized in guinea-pig epidermis. These are carboxylic esterase, acid phosphatase, pyrophosphatase, and arylsulphatase A and B. Their properties are consistent with those of lysosomal enzymes.

Dental anomalies were observed in 43 of 1,226 barren-ground caribou (Rangifer tarandus groenlandicus) taken between 1966 and 1968. In five of these 43 animals, the mandibles had deformities which radiography showed to be the result of dental abscesses in four cases and probably of a trauma in the other. The absence of actinomycotic lesions of the jaw bones of these 1,226 animals, and of more than 500 examined previously, indicates that "lumpy jaw" is rare in barren-ground caribou. The authors suggest the use of radiography to determine the nature of bone growth on skeletal remains, in the absence of soft tissues for examination for Actinomyces, either microscopically or by cultural methods.

1. Crude extracts and partially purified enzyme preparations from potato tubers catalyse, at pH 5-7, the conversion of linoleic acid hydroperoxides to a range of oxygenated fatty acid derivatives. 2. 9-D- and 13-L-hydroperoxide isomers are converted at similar rates to equivalent (isomeric) products. 3. The major products from the 13-hydroperoxide isomer were identified as the corresponding monohydroxydienoic acid derivative, threo-11-hydroxy-trans12,13-epoxy-octadec-cis9-enoic acid and 9,12,13-trihydroxy-octadec-trans10-enoic acid. The corresponding products from the 9-hydroperoxide were the monohydroxydienoic acid, 9,10-epoxy-11-hydroxy-octadec-12-enoic acid and 9,10,13-trihydroxy-octadec-11-enoic acid. 4. No separation of activities forming the different products was achieved by partial purification of enzyme extracts. 5. Product formation was unaffected by EDTA, CN-, sulphydryl reagents or glutathione but was reduced by boiling the extracts. 6. This system is compared with the 9-hydroperoxide-specific enzymic formation of divinyl ether derivatives by potato extracts.

The hydrolysis of p-nitrophenyl phosphate by wheat germ acid phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.2) has been investigated in mixtures of aqueous buffers with acetone, dioxane and acetonitrile. The enzyme was either in free solution or immobilized on a pellicular support which consisted of a porous carbonaceous layer on solid glass beads. The highest enzyme activity was obtained in acetone and acetonitrile mixed with citrate buffer over a wide range of organic solvent concentration. In 50% (v/v) acetone both V and Km of the immobilized enzyme were about half of the values in the neat aqueous buffer, but the Ki for inorganic phosphate was unchanged. In 50% (v/v) mixtures of various solvents and citrate buffers of different pH, the enzymic activity was found to depend on the pH of the aqueous buffer component rather than the pH of the hydro-organic mixture as measured with the glass-calomel electrode. The relatively high rates of p-nitrophenol liberation in the presence of glucose even at high organic solvent concentrations suggest that transphosphorylation is facilitated at low water activity.

The characterization and localization of a Ca(2+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) in the tooth germ of the porcine fetus are reported. This enzyme, a microsome fraction, is preferentially activated by Ca(2+). In the presence of 0.5 mM ATP, maximal enzyme activity is obtained at 0.5--1.0 mM CaCl2. The maximal rate of ATP hydrolysis is approx. 20 mumol per h per mg of protein as the enzyme preparation is used here. At optimal Ca(2+) concentration, the Mg(2+) has an inhibitory effect. The enzyme does not require Na+ or/and K+ for activation by Ca(2+). Other nucleotide triphosphates may serve as the substrate, but V for ATP is the highest. The Km for ATP is 8.85 - 10(-5) M. The optimal pH for Ca(2+) activation of the enzyme lies around 9.2. Well known inhibitors of (Na+ + K+)-ATPase, mitochondria ATPase and Ca(2+)-ATPase in the erthrocyte do not inhibit the enzyme. In the subcellular order the enzyme may be assumed to be localized in the smooth endoplasmic reticulum fraction containing cell and Golgi body membrane fragments and in the tissue order in the enamel organ containing an ameloblast layer, stratum intermedium and stellate reticulum.

Enzymes capable of hydrolyzing esters of thiocholine have been assayed in extracts of Solanum melongena L. (eggplant) and Zea Mays L. (corn). The enzymes from both species are inhibited by the anti-cholinesterases neostigmine, physostigmine, and 284c51 and by AMO-1618, a plant growth retardant and they both have pH optima near pH 8.0. The enzyme from eggplant is maximally active at a substrate concentration of 0.15 mM acetylthiocholine and is inhibited at higher substrate concentrations. On the basis of this last property, the magnitude of inhibition by the various inhibitors, and the substrate specificity, we conclude that the enzyme from eggplant, but not that from corn, is a cholinesterase.

A purification procedure for creatine kinase (EC 2.7.3.2) from muscle of the monke35--170 muequiv H+/mg protein per min at 30 degrees C and a yield of approx. 0.5 g/kg muscle. Assuming equilibrium kinetics, synergistic binding of substrates at one catalytic site is found for both the forward and back reactions. Kinetic constants for the binding of each substrate to the free enzyme and the enzyme-second substrate complex are determined and are compared with those for the enzyme from other species. Inhibition by small anions is determined in the presence of different combinations of substrates and products. SO4(2-) inhibits by simple competitive inhibition and probably binds at the site of the transferrable phosphoryl group. Inhibition by NO3-, NO2-, SCN- and Cl- is more complex and these ions are suggested to mimic the transferrable phosphoryl group in a planar transition-state complex. These anions stabilize the dead-end complex, enzyme-creatine-MgADP, which lacks the transferable phosphoryl group. The effects of these anions on the dissociation constants of the enzyme-substrate complexes is reported and is in accord with the above hypothesis. The dead-end complex in the absence of anion does not protect the essential thiol group against inhibition by iodoacetamide. Addition of NO3- or Cl- to the dead-end complex or a substrate equilibrium mixture without anion confers protection. The essential thiol group is inhibited by iodoacetamide at a rate which is essentially independent of pH over the normal stability range of the enzyme. Contrary to our previous report this pH independence is not altered by the presence of dead-end complex, creatine plus MgADP, in the presence or absence of anion or in the presence of a substrate equilibrium mixture. It is inferred that the 'essential' thiol group of the monkey enzyme has essentially the same properties as that of the rabbit enzyme. In consequence, the inferences made about the role of this group based on our previous work on the monkey enzyme are no longer valid. The present findings are compatible with the essential thiol group playing a conformational role in the catalytic process.

Two rabbit erythrocyte casein kinases, GTP:casein kinase I and GTP:casein kinase II, have been purified 29 000- and 47 000-fold, respectively. Studies employing sucrose density gradient centrifugation indicate that kinase I has a molecular weight of about 9.5 - 10(5) (25 S) and kinase II about 1.4 - 10(6) (32 S). These enzymes can utilize either ATP or GTP as the phosphoryl donor. Among various protein substrates examined, these kinases catalyze the phosphorylation of casein greater than 50% dephosphorylated phosvitin congruent to 50% dephosphorylated casein greater than phosvitin. Histones, protamine and bovine serum albumin are poor phosphoryl acceptors. Kinetic data indicate that both enzymes are inhibited by high casein substrate concentrations which may be partially relieved by NaCl. Both phosphotransferases require Mg(2+) for activity and are optimally active at pH 9.0. The enzymes have apparent Km values of 2.5 - 10(-5) M for GTP, 2 - 10(-5) M for ATP, and 0.4--0.6 mg/ml for casein. The incorporation of the terminal phosphate of GTP into casein as catalyzed by these enzymes is inhibited to varying degrees by ATP, ITP, ADP, and GDP but not by UTP, CTP, GMP, adenosine 3':5'-cyclic monophosphate, and guanosine 3':5'-cyclic monophosphate. In addition, NaF and 2,3-diphosphoglyceric acid are also found to inhibit the activity of both kinases. The effect of 2,3-diphosphoglycerate is interesting and suggests that this metabolite may regulate the activity of the casein kinases in the red blood cells.

A strain of Bacillus sp (Bacillus R-4) produces a protease and a carbohydrolase both of which have the ability to lyse Rhizopus cell walls. Of the enzymes, the carbohydrolase has been purified to an ultracentrifugally and electrophoretically homogeneous state, and identified as a chitosanase. The enzyme was active on glycol chitosan as well as chitosan. Molecular weight of the purified enzyme was estimated as 31 000 and isoelectric point as pH 8.30. The enzyme was most active at pH 5.6 and at 40 degrees C with either Rhizopus cell wall or glycol chitosan as substrate, and was stable over a range of pH 4.5 to 7.5 at 40 degrees C for 3 h. The activity was lost by sulfhydryl reagents and restored by either reduced glutathione of L-cysteine. An abrupt decrease in viscosity of the reaction mixture suggested an endowise cleavage of chitosan by this enzyme.

1. The pH dependencies of the apparent Michaelis constant for oxidized glutathione and the apparent turnover number of yeast glutathione reductase (EC 1.6.4.2) have been determined at a fixed concentration of 0.1 mM NADPH in the range pH 4.5--8.0. Between pH 5.5 and 7.6, both of these parameters are relatively constant. The principal effect of low pH on the kinetics of the enzyme-catalyzed reaction is the observation of a pH-dependent substrate inhibition by oxidized glutathione at pH less than or equal 7, which is shown to correlate with the binding of oxidized glutathione to the oxidized form of the enzyme. 2. The catalytic activity of yeast glutathione reductase at pH 5.5 is affected by the sodium acetate buffer concentration. The stability of the oxidized and reduced forms of the enzyme at pH 5.5 and 25 degrees C in the absence of bovine serum albumin was studied as a function of sodium acetate concentration. The results show that activation of the catalytic activity of the enzyme at low sodium acetate concentration correlates with an effect of sodium acetate on a reduced form of the enzyme. In contrast, inhibition of the catalytic activity of the enzyme at high sodium acetate concentration correlates with an effect of sodium acetate on the oxidized form of the enzyme.

Theory is presented relating to the binding of an effector to two states of a protein acceptor coexisting in equilibrium. The problem is treated in terms of the four possible cases which specify relations between numbers of binding sites and intrinsic binding constants relevant to the acceptor states. It is shown that a distinction between these cases may be possible on the basis of the form of a plot of unbound effector concentration versus the constituent equilibrium coefficient which may be calculated from the sedimentation coefficient of the protein constituent. Particularly noteworthy in this respect is the finding that a turning point may exist in this plot for defined conditions with systems in which binding sites are not conserved (and binding affinities are altered) on polymer formation. The latter type of system is exemplified by studies on methaemoglobin A in 0.25 M sodium acetate, pH 5.4. In the absence of added organic phosphate effectors, a dimer-tetramer equilibrium operates governed by an association constant of 4.15 +/- 0.06 X 10(3) 1/mol, determined from sedimentation equilibrium results. Correlation of sedimentation velocity and equilibrium results shows that addition of adenosine 5'-triphosphate (ATP) results in its binding to one site on each of the dimeric (alpha beta) and tetrameric (alpha beta)2 species with intrinsic binding constants 1.03-10(3)-1.20-10(3) and 1.1-10(4)-2.1-10(4) 1/mol, respectively. It is also shown that 2,3-diphosphoglycerate perturbs the dimer-tetramer equilibrium in a similar way to ATP.

Human hemoglobin was spin labeled with 4-isothiocanato-2,2,6,6-tetramethyl-piperdinooxyl, which is known to bind specifically to the N-terminal alpha-amino groups of proteins and slightly to the reactive sulfhydryl groups. Electron spin resonance (ESR) analysis indicated a partially resolved five-line spectrum, suggesting that the label was attached to at least two different binding sites. Using specific blocking reagents prior to spin labeling, the two binding sites were attributed to the sulfhydryl group of beta-93 (immobile) and the alpha-amino group of the N-terminal valines (mobile). The relative motion of the spin at one set of binding sites was restricted regardless of the state of ligation and pH, while the motion at the other site showed dependence on those parameters, e.g. the spin-labeled N-terminal ends of deoxyhemoglobin have restricted motion at all pH ranges studied, while those of oxyhemoglobin are relatively free to move at the basic pH range, but become more restricted in the acidic pH range.

Poly(8-aminoguanylic acid) has in neutral solution a novel ordered structure of high stability. The 8-amino group permits formation of three hydrogen bonds between two residues along the "top", or long axis, of the purines. The usual hydrogen bonding protons and Watson-Crick pairing sites are not involved in the association. The bonding scheme has a twofold rotation axis and is hemiprotonated at N(7). Poly(8NH2G) is converted by alkaline titration (pK = 9.7) to a quite different ordered structure, which is the favored form over the range approximately pH 10-11. The bonding scheme appears to be composed of a planar, tetrameric array of guanine residues, in which the 8-amino group does not participate in interbase hydrogen bonding. Poly (8NH2G) does not interact with poly(C) in neutral solution because of the high stability of the hemiprotonated G-G self-structure. Titration to the alkaline plateau, however, permits ready formation of a two-stranded Watson-Crick helix. In contrast to the monomer 8NH2GMP, poly(8NH2G) does not form a triple helix with poly(C) under any conditions. The properties of the ordered structures are interpreted in terms of a strong tendency of the 8-amino group to form a third interbase hydrogen bond, when this possibility is not prevented by high pH.

Increasing concentrations of chloride were found to increase the resolution between two visible absorbance spectral transitions associated with acidification of ferricytochrome c. Analysis of a variety of spectral and viscosity measurements indicates that protonation of a single group having an apparent pK of 2.1 +/- 0.2 and an intrinsic pK of about 5.3 displaces the methionine ligand without significantly perturbing the native globular conformation. Analysis of methylated ferricytochrome c suggests that protonation of a carboxylate ion, most likely a heme propionate residue, is responsible for displacement of the methionine ligand. Addition of a proton to a second group having an apparent pK of 1.2 +/- 0.1 displaces the histidine ligand and unfolds the protein from a globular conformation into a random coil. It is most likely that the second protonation occurs on the imidazole ring of the histidine ligand itself. Chloride is proposed to perturb these transitions by ligation in the fifth coordination position of the heme ion. Such ligation stabilizes a globular conformation of ferricytochrome c at pH 0.0 and 25 degrees.

The electrochemical behaviour of ferricytochrome c, metmyoglobin and methemoglobin was studied using d.c., a.c. and differential pulse polarography, and controlled potential electrolysis. 1. The three hemoproteins yield d.c. polarographic steps, and peaks in differential pulse polarograms, the height of which is proportional to concentration. The charge transfer is influenced by strong adsorption. 2. The concentration dependence of the a.c. polarograms indicates structural changes in the adsorbed molecules. 3. The reduction products of controlled potential electrolysis of metmyoglobin and methemoglobin have absorption spectra identical with the native control samples. The affinity for oxygen and the cooperativity in hemoglobin are not affected by the reaction at the electrode. 4. The charge transfer proceeds via adsorbed, already reduced, molecules to freely diffusible proteins.

Electron microscopy showed that commerical poly I: C consisted of molecules varying in length from less than 0.05 nm to more than 5 nm and also in morphology . To clarify the relationship between its molecular size and interferon-inducing activity, poly I: C was sonicated or fractionated by sucrose density gradient centrifugation, and the molecular length distribution and interferon-inducing activity of each preparation was determined in vivo and in vitro. The results showed that (1) poly I : C molecules 0.1-0.3 nm long were the most effective for interferon induction; (2) sonication of poly I : C reduced its molecular length and also the interferon-inducing activity, the degree of reduction varying in different fractions; and (3) the interferon-inducing activity of poly I: C of 0.1-0.3 nm obtained by sucrose density gradient centrifugation was higher than that poly I: C of corresponding length prepared by sonication.

Distribution of Lednice (Yaba 1) virus antigen (LVA) was followed by immunofluorescene (IF) in chick embryos inoculated into the yolk sacs. Positive fluorescence of LVA was observed in neurons and neuroblasts of the developing brain, spinal cord and spinal ganglia as well as in skeletal muscles, heart muscle, vascular endothelium and lung mesenchyma. In the yolk sac, foci of specific fluorescence were occasionally seen in endothelium cells of vessels and in islands of extraembryonic haematopoesis. At sites corresponding to the occurrence of LVA, extensive oedema was accompanied by extravazation of erythrocytes and accumulation of white blood cells. The nature of tissues in which the virus replicates was discussed from the point of view of LVA distribution and the morphological lesions observed.

The influence of the sympathetic nervous system on the cerebral circulatory response to graded reductions in mean arterial blood pressure was studied in anesthetized baboons. Cerebral blood flow was measured by the 133Xe clearance method, and arterial blood pressure was decreased by controlled hemorrhage. In normal baboons, the constancy of cerebral blood flow was maintained until mean arterial blood pressure was approximately 65% of the base-line value; thereafter, cerebral blood flow decreased when arterial blood pressure was reduced. Superior cervical sympathectomy of 2-3 weeks duration did not affect the normal response. In contrast, both acute surgical sympathectomy (cervical trunk division) and alpha-receptor blockade (1.5 mg/kg of phenoxybenzamine) enhanced the maintenance of cerebral blood flow in the face of hemorrhagic hypotension in that cerebral blood flow did not decrease until mean arterial blood pressure was approximately 35% of the base-line value. The results indicate that the sympathetic nervous system is not involved in the maintenance of cerebral blood flow in the face of a fall in arterial blood pressure. Indeed, the implication is that the sympathicoadrenal discharge accompanying hemorrhagic hypotension is detrimental to, rather than responsible for, cerebral autoregulation.

Dairy cows infected naturally with Coxiella burnetii as evidenced either by presence of phase II agglutinating antibodies in the blood or by shedding C. burnetii in the milk, were vaccinated subcutaneously with formalin-killed phase I C. burnetii organisms. Attempts to demonstrate C. burnetii in the milk of vaccinated dairy cows 47 days after vaccination were negative, while continuous shedding of C. burnetii in the milk of control non-vaccinated dairy cows was repeatedly demonstrated in the course of 123 days (period of investigation). No harmful systemic reaction following vaccination was observed.

The approach to the problem of oncogenesis of tumorigenic viruses is compared and analyzed from the position of the Altshtein-Vogt hypothesis and from that of the general theory of oncogenesis advanced by the present author. In contrast to the hypothesis of Altshtein-Vogt dealing mainly with the problem of oncogene origin, the general theory of oncogenesis not only defines concretely the origin of the oncogene and the essence of its product, but also makes it possible to understand why, when and how integration of the oncogene with the genome of the cell leads to the transformation of the cell into a benign cell and when into a malignant tumour cell. An analysis of the essence of the "oncogene position effect" from this standpoint shows that an integration, similar in its mechanism but differing in polarity, of the genome of other viruses with the cell genome should lead to the formation of a corresponding antiviral stable (life-long) immunity or also to the emergence of pseudoautoimmune disease of the type caused by "slow" viruses.

To evaluate responses to medical therapy in ulcerative colitis, rectal biopsies of patients with active untreated disease, individuals with positive and negative sigmoidoscopic findings treated with salicylazosulfapyridine, prednisone and 6-mercaptopurine, alone and in combinations and noncolitis controls were compared histologically. Predominant histological observations were analyzed statistically. There were fewer crypt abscesses but more mucosal edema after all forms of therapy. Quantitative histopathological analysis failed to demonstrate that the response to one drug was significantly different from another.

The degree of serological relatedness of three isolates of bean yellow mosaic virus (BYMV) was studied. One common antigenic group (m) was demonstrated in all 3 isolates. In addition, another antigenic group (a) was demonstrated in the isolate FvM1. This group was absent from the isolates TpM3 and TpM11, in which the antigenic group n was found. Antisera to the 3 isolates contained the corresponding antibody groups. The antibody group (M) shared by all 3 BYMV isolates was present in the FvM1 antiserum in a level only a little higher than the second antibody group (A). Antisera to TpM3 and TpM11 isolates showed only a low titre of M antibody, while the second antibody group (N) reached titres from 512 to 1024. Cross-absorption tests revealed serological identity of both isolates of the "necrotic type" (TpM3 and TpM11) and allowed to estimate the degree of their serological relatedness to representatives of the "mosaic type" isolates of BYMV (FvM1).

It is proposed that the direct analgesic effect of morphine becomes attenuated over the course of successive administrations of the narcotic by a conditioned, compensatory, hyperalgesic response elicited by the administration procedure, the net result being analgesic tolerance. Using the "hot plate" analgesia assessment situation with rats, this conditioning view of tolerance is supported by several findings: (a) It is necessary to have reliable environmental cues predicting the systemic effects of morphine if tolerance is to be observed, (b) a hyperalgesic conditioned response may be observed in morphine-tolerant subjects when drug administration cues are followed by a placebo, and (c) merely by repeatedly presenting environmental cues previously associated with morphine (but now presented with a placebo), morphine tolerance can be extinguished.

The near-ultraviolet circular dichroism (CD) of three homogeneous anti-type III pneumococcal antibodies in the absence and the presence of the specific hexasaccharide ligand was studied. In addition recombinations and hybridizations of H and L chains derived from two of these antibodies were carried out and the CD spectra of bound and free reconstituted IgG molecules were measured. The results indicate that the CD spectra of the native antibodies in the 260-310-nm range are very similar in shape and sign and exhibit a positive band at 285 nm. The homologous reconstituted antibody molecules exhibited CD spectra very similar in shape and sign to those of the native antibody molecules although recombinant molecules are no longer stabilized by interchain disulfide bonds. Upon addition of the hexasaccharide ligand, a significant decrease in amplitude of the CD spectra (18-21%) occurred in all three native antibodies and their Fab fragments as well as in the homologous recombinant molecules. No CD spectral changes could be detected upon interaction of the hapten ligand with the heterologous recombinants. All homogeneous antibodies studied exhibited fluorescence quenching upon oligosaccharide binding and a blue shift of the emission maximum. This property allowed the determination of the binding constant of one selected antibody to be made. Taken together, CD and fluorescence spectroscopic data suggest that oligosaccharide ligands induced detectable conformational changes in the Fab fragment of the antibody.

The reduction of metmyoglobin by the iron(II) complex of trans-1,2-diaminocyclohexane-N,N,N'N'-tetraacetate (FeCDTA2-) has been investigated. The equilibrium constant, measured spectrophotometrically, is 0.21 with a resulting reduction potential of 0.050 V for Mb0. The rate constant for the reduction is 28 M-1 sec-1 with a deltaH ++ of 13 kcal M-1 and deltaS ++ of -11 eu. Both CN- and OH- inhibit the reduction because of the relatively low reactivity of cyanometmyoglobin (Mb+CN-) and ionized metmyglobin (Mb+OH-). The rate constant for the reduction of Mb+CN- by FeCDTA2- is 4.0 X 10(-2) M-1 sec-1 and that for reduction of Mb+OH- is 4.8 M-1 sec-1. The nitric oxide complex of metmyoglobin is reduced with a rate constant of 10 M-1 sec-1. The kinetics of oxidation of oxymyoglobin by FeCDTA- were studied. The data are consistent with a mechanism where oxidation takes place entirely through the deoxy form. A rate constant of 1.45 X 10(2) M-1 sec-1 was calculated for the oxidation of deoxymyoglobin by FeCDTA-, in equilibrium constant and rate constant for reduction. The above data are discussed in terms of a simple outer-sphere reduction reaction.

The contractile proteins from arterial smooth muscle are highly soluble, and can be extracted at I = 0.05. However, they can be precipitated by a prolonged dialysis at pH 6 to give an actomyosin with a high, although variable, actin:myosin ratio. The sedimentation behavior of this actomyosin at high ionic strength was examined as a function of pH, protein concentration and composition by preparative ultracentrifugation. Comparisons with synthetic skeletal muscle actomyosins of similar composition demonstrated significant differences in the behaviors of these two systems. It was found that much smooth muscle actomyosin is not dissociated by normally relaxing conditions, and that it sediments at a slower rate than F-actin. The solubility of the supernatant protein (a myosin-enriched actomyosin) in 0.2 M K Cl (pH 7) depended on the pH during centrifugation. A lower solubility was associated only with a higher actin concentration in the supernatant, suggesting a dependence on actin repolymerization. Pure myosin was selectively precipitated from the supernatant by polyethylene glycol-6000, but only when the protein was soluble at low ionic strength. The solubility of purified myosin was similar to that of myosin from striated muscles. A relationship between the presence of depolymerized actin and the high solubility of smooth muscle contractile proteins is suggested.

Photosystem II reaction center components have been studied in small system II particles prepared with digitonin. Upon illumination the reduction of the primary acceptor was indicated by absorbance changes due to the reduction of a plastoquinone to the semiquinone anion and by a small blue shifts of absorption bands near 545 nm (C550) and 685 nm. The semiquinone to chlorophyll ratio was between 1/20 and 1/70 in various preparations. The terminal electron donor in this reaction did not cause large absorbance changes but its oxidized form was revealed by a hitherto unknown electron spin resonance (ESR) signal, which had some properties of the well-known signal II but a linewidth and g-value much nearer to those of signal I. Upon darkening absorbance and ESR changes decayed together in a cyclic or back reaction which was stimulated by 3-(3,4 dichlorophenyl)-1,1-dimethylurea. The donor could be oxidized by ferricyanide in the dark. Illumination in the presence of ferricyanide induced absorbance and ESR changes, rapidly reversed upon darkening, which may be ascribed to the oxidation of a chlorophyll a dimer, possibly the primary electron donor of photosystem II. In addition an ESR signal with 15 to 20 gauss linewidth and a slower dark decay was observed, which may have been caused by a secondary donor.