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Biomedical subjects

R T Hall

Publications and source records attributed to R T Hall.

At least 91 records · Page 5Linked to original sources
PubMed1978

Role of antibody and complement in opsonization of group B streptococci.

A requirement for the classic complement pathway in opsonization of group B streptococci was observed by using both a chemiluminescence and a radiolabeled bacterial uptake technique. The classic pathway increased levels of opsonization for types Ia and II stock and wild strains and for some type III wild strains. In contrast, other type III wild strains and the type III stock strain had accelerated kinetics of uptake in the presence of an intact classic pathway, but the level of opsonization was unchanged from that with antibody alone. We could not demonstrate a significant role for the alternative pathway in opsonizing stock or wild strains of group B streptococci. Futhermore, electrophoretic and complement consumption analysis by hemolytic titration failed to reveal alternative pathway activation by the majority of strains of this group. Therapy aimed at supplying opsonins for these organisms will require the presence of type-specific antibody.

Antibodies, Bacterial↗
PubMed1978

Postneonatal infant mortality in infants to a neonatal intensive care unit.

The postneonatal infant mortality (PNIM) of 2,205 infants admitted to a neonatal intensive care unit from January 1971 to December 1974 was 44 in 1,000 infants who survived to age 28 days. This rate is approximately ten times that of the general population. Congenital malformations (59%), infections (12%), sudden infant death syndrome (10%), and asphyxial brain damage (10%) were the most common causes of death. One third (26) of the infants remained in the hospital whereas two thirds (52) had been dismissed prior to death. All who remained in the hospital plus 36 who had been dismissed died of severe illnesses that were incompatible with prolonged survival. The remaining PNIM was 10 in 1,000 neonatal survivors. This rate is still twice that of the general population. These deaths occurred in infants who were apparently well at the time of dismissal and subsequent examinations. Sudden infant death syndrome and infections constituted the largest portion of this mortality. Factors contributing to mortality in this group were poor socioeconomic status and low birth weight. Maternal age, race, marital status, and neonatal illnesses including apnea were not significantly related. Factors that appear to be important in the birth of high-risk infants continued to be operative in the postneonatal period, and contribute to a high mortality in apparently normal infants dismissed from the neonatal intensive care unit.

Abnormalities, Multiple↗
PubMed1977

Glucose disappearance in infants of diabetic mothers. I. Relationship to maternal glucose tolerance and insulin production.

Glucose disappearance and insulin response were determined in mother--infant pairs of normal, gestational diabetic and diabetic pregnancies following an intravenous glucose load. Mothers were studied in the third trimester of pregnancy and at least 6 wk postpartum. Significant differences were present in glucose disappearance and insulin response in both gestational diabetic and diabetic mothers during pregnancy compared with the control group. Infants were studied within 4 h of birth while fasting, and glucose and insulin levels followed through the first 3 days of life. Neonatal hypoglycemia did not occur and glucose disappearance (KT) was not different among the three groups. There was no correlation between maternal glucose tolerance or insulin production and that of their infants. The only distinguishing factor among the infants was higher insulin production in infants of diabetic mothers during the 60-min intravenous glucose tolerance test which persisted up to 4 h following the infusion. It is concluded that factors other than the degree of maternal glucose tolerance are responsible for the development of neonatal hypoglycemia in infants of diabetic mothers, most notably control of maternal diabetes, the amount of glucose infused immediately before delivery and neonatal glucose production.

Blood Glucose↗
PubMed1977

Glucose disappearance in infants of diabetic mothers. II. Relationship to lowest neonatal blood glucose and amniotic fluid insulin.

Neonatal glucose disappearance (KT) was measured in 26 infants of insulin-dependent diabetic mothers within the first 2 h of life. A significant correlation was found between the KT and the lowest blood glucose (LBG) in the first day of life (r = 0.64, P less than 0.001). None of 21 infants developed a LBG less than 20 mg/dl when the KT was less than 3.0%/min in contrast to 4 of 5 whose KT was greater than 3.0%/min (P less than 0.001). Amniotic fluid (AF) glucose and insulin were determined in 42 samples from 18 of these patients in the third trimester of pregnancy. There was a significant correlation between AF insulin values and the neonatal KT (R = 0.76, P less than 0.001). The correlation was higher when only amniotic fluid values obtained on the day of delivery were considered (n = 17, r = 0.90, P less than 0.001). 1 of 13 infants developed a LBG less than 20 mg/dl when the amniotic fluid insulin was less than 100 mu U/ml on the day of delivery in contrast to 3 of 4 whose AF insulin was greater than 100 mu U/ml (P less than 0.001). No correlation of AF glucose was found with infants' KT or LBG. These data suggest that both neonatal KT and AF insulin are of value for predicting neonatal hypoglycemia and detecting infants who will require treatment for its prevention.

Amniotic Fluid↗
PubMed1977

The effects of single infusion of hypertonic sodium bicarbonate on body composition in neonates with acidosis.

Acid-base equilibrium and plasma and red blood cell water and solute were evaluated in a group of asphyxiated, acidotic neonates prior to and following infusion of hypertonic NaHCO3. The dose was calculated to correct the deficit of base in a bicarbonate space of 400 ml/kg and was given at a rate of 0.3 mM NaHCO3/kg/minute. All of the infants with RDS and two of the five with other forms of asphyxia received ventilatory assistance during the infusion. The quantity of base infused was sufficient to alter acid-base balance and shift whole blood and red blood cell pH values toward normal. The changes in body composition 3 minutes following the infusion indicate that the osmotic load imposed by the hypertonic NaHCO3 caused a shift of solute-free water into the interstitial and intravascular fluids. During the period from 3 to 30 minutes following the infusion there was redistribution of extracellular water and solute so that plasma volume and [Na]PL decreased. Since there was no evidence of an intracellular shift of solute, we hypothesize that the changes in body composition between 3 and 30 minutes postinfusion were in part the consequence of gradual penetration of transcellular fluids by Na. Osmotic inactivation of ECF Na by sequestration with connective tissue polyelectrolytes may also play a role. These studies' do not provide an answer to the clinical problem of whether the beneficial effects of prompt correction metabolic acidosis outweigh the potenially harmful effect of the osmotic alterations that accompany rapid infusion of hypertonic NaHCO3.

Acid-Base Equilibrium↗
PubMed1977

Radiographic findings in early onset neonatal group b streptococcal septicemia.

Chest roentgenograms obtained in the first two days of life from 67 infants with respiratory distress were reviewed to determine whether the radiographic features of group B streptococcal septicemia were diagnostic or distinctive. The retrospective review contained 24 infants with proven and 14 with suspected septicemia, as well as 29 patients with other causes of respiratory distress. The films were reviewed in random order by two pediatric radiologists without their prior knowledge of clinical or laboratory data. Typical radiographic appearance of pneumonia was present in only ten of the 24 proven and two of the 14 suspected cases of group B streptococcal sepsis. The radiographic pattern of respiratory distress syndrome (RDS) was just as common among these patients. The most prominent associated radiographic feature of infants with proven septicemia was cardiomegaly which was significantly increased when compared with infants who had other causes of respiratory distress (P less than .001). X-ray recognition of neonatal group B streptococcal septicemia is limited because of superimposition of roentgen patterns probably related to associated disorders. Pediatrics, 59:1006-1011, 1977, NEWBRON, SEPTICEMIA, GROUP B STREPTOCOCCUS.

Humans↗
PubMed1976

Antibiotic treatment of parturient women colonized with group B streptococci.

A prospective study was conducted among third-trimester parturient women with cervical or urethral colonization with group B streptococci to determine the influence of antibiotic treatment on subsequent colonizations among their infants. Cultures were obtained from dry swabs inoculated directly onto selective blood agar media containing neomycin and naladixic acid. Seventy-four women were found to be colonized among 1,098 cultured (7%). A significant reduction in colonization was noted among mothers treated with ampicillin within three weeks of completion of therapy. This difference was no longer apparent at delivery. There was likewise no difference in the colonization rate of infants in the treatment and no-treatment groups. The data suggest that additional measures must be undertaken to prevent maternal recolonization.

Ampicillin↗
PubMed1976

Neonatal pneumatosis coli: a mild form of neonatal necrotizing enterocolitis.

A distinctive form of necrotizing enterocolitis was observed in seven newborn infants in a 4 1/2-year period. Characteristically these patients had gross blood in the stools, but other local and systemic signs were mild or absent. Radiography mainly revealed submucosal intramural intestinal gas which was limited to the colon (pneumatosis coli). There was no evidence of small bowel involvement as judged by the absence of small intestinal pneumatosis or distension. This form of colonic disease should be recognized as a benign variety of neonatal necrotizing enterocolitis that carries a favorable prognosis and responds to medical management without sequelae.

Enterocolitis, Pseudomembranous↗
PubMed1976

Total parenteral alimentation via indwelling umbilical catheters in the newborn period.

Total parenteral alimentation (TPA) was delivered to 80 infants via indwelling umbilical artery and to 9 via indwelling umbilical venous catheters. The primary indication for catheter placement and maintenance was monitoring of arterial blood gases (umbilical venous catheter tip in left atrium) in a group of sick neonates requiring increased inspired oxygen or assisted ventilation. Results were compared with those from 23 infants who had tunnelled jugular catheters for a variety of chronic medical and surgical problems preventing gastric or intestinal feeding. A mean weight gain was achieved in both groups. Mortality and morbidity rates were similar in both groups. The most common complications were infection and thrombotic phenomena. Metabolic complications were few. It is concluded that infusing TPA solutions via indwelling umbilical catheters presents no greater risk than infusion via tunnelled jugular catheters, and provides a method for supplying adequate caloric intake for growth during the acute stage of illness.

Catheterization↗
PubMed1976

Assessment of group B streptococcal opsonins in human and rabbit serum by neutrophil chemiluminescence.

The factors important in host defense against group B streptococci are not well understood. The role of antibody and complement in the prevention of serious infection by these organisms is not known because, to date, a reliable measure of functional opsonic activity has not been developed. Recently, it has been shown that neutrophils produce a chemiluminescence after ingestion of particulate matter, and that this event can be detected and quantitated in a liquid scintillation system. We have adapted the chemiluminescence procedure to examine rabbit hyperimmune and human serum for the presence of group B streptococcal opsonins. Group B streptococci of types Ia, II, and III that were opsonized in homologous but not heterologous type serum produced a peak in chemiluminescence when added to normal human neutrophils. Such activity was correlated, in each instance, with ingestion of bacteria by neutrophils and deposition of immunoglobulin and C3 on the bacterial surface as detected by indirect immunofluorescence. With this assay, we have examined sera from colonized and diseased patients for the presence of opsonins to types Ia, II, and III group B streptococci. Maternal sera often contained type-specific opsonins which resided in the IgG fraction and which crossed the placenta to appear in paired cord specimens. 63% of patients colonized with group B streptococci had serum opsonins to their colonizing type of organism. In contrast, none of the 15 patients with sepsis or meningitis had opsonins directed against their infecting strain. These data suggest that the lack of type-specific opsonins to group B streptococci may be one of the important factors in determining host susceptibility to systemic infection with strains of this group.

Animals↗
PubMed1975

Chronic pulmonary disease in neonates with assisted ventilation.

Chronic lung disease in the form of stage III or IV bronchopulmonary dysplasia (BPD) was found to occur among nine of 188 infants receiving intermittent positive-pressure ventilation for respiratory insufficiency. None occurred in infants ventilated with a mask alone. The duration of endotracheal intubation was not significantly longer in patients developing BPD; however, the duration of exposure to inspired oxygen greater than 60 percent was significantly longer in that group (mean, 141 hours). A previously undescribed form of chronic lung disease was found to occur among nine of 150 infants ventilated because of underlying idiopathic respiratory distress syndrome. A radiographic appearance of diffuse haziness with loss of identifiable lung markings occurred at 5 to 15 days of age and was not associated with clinical signs or symptoms or increased oxygen needs. These changes disappeared in one to five days.

Birth Weight↗