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Biomedical subjects

G W Chance

Publications and source records attributed to G W Chance.

At least 37 records · Page 2Linked to original sources
PubMed1985

Laryngeal atresia, pleurodesis, and diaphragmatic hypertrophy in a newborn infant with findings relevant to fetal lung development.

A rare congenital malformation, cartilaginous subglottic laryngeal atresia, was found associated with developmental growth disturbances in the lungs (hypoplasia), diaphragm (hypertrophy), and pleural cavities (pleurodesis) in a newborn premature male infant who died immediately after birth. Because of coexistent esophageal atresia, tracheoesophageal fistula, and anal atresia, the lower respiratory tract and gastrointestinal canal together formed a closed system throughout fetal life. A mechanism whereby diaphragmatic hypertrophy and mesenchymal obliteration of the pleural cavities may have evolved during uterine development is suggested. Since pulmonary hypoplasia was also present, an explanation of this unique constellation of development abnormalities has a bearing on normal lung development.

Abnormalities, Multiple↗
PubMed1984

'Normal' haemostasis parameters: a study in a well-defined inborn population of preterm infants.

Coagulation studies were performed in a well-defined inborn population of preterm neonates in cord blood and arterial blood obtained at age 48 h. Eighty infants fulfilled all the inclusion criteria. Our results show an increase in the hepatic vitamin K1 dependent and independent factors with postnatal age. The APTT became shorter, the factor II-VII-X, alpha 2-antiplasmin, plasminogen activities and fibrinogen level rose with increasing postnatal age. We found no change in the platelet parameters measured with postnatal age except that the megathrombocyte index was increased at age 48 h in infants less than 29 weeks gestation. There was little change with gestational age of any factors except the vitamin K1 dependent factors. Factor II-VII-X activity rose and the APTT became shorter with increasing gestational age. Many of the haemostasis results did not fall within the normal adult range. We discuss the significance of 'abnormal' and 'normal' results in preterm infants.

Blood Coagulation↗
PubMed1984

Intraventricular haemorrhage--timing of occurrence and relationship to perinatal events.

A total of 150 infants born at or before 34 weeks gestation had serial cranial ultrasound scans at age 8, 16, 24, 36, 48 h and 1 week. The overall incidence of IVH was 26%, but for infants less than 1500 g it was 51% and 50% of all haemorrhages were first detected in the first 8 h of life. Low-outlet forceps delivery and caesarean section offered some protection, but umbilical cord blood gas analysis did not support the hypothesis that hypoxia was causal. Respiratory distress and its complications were significantly associated with IVH. The more severe haemorrhages occurred in the less mature infants. The overall mortality in the study was 27% for the IVH group and 1.8% for the non-IVH group.

Adult↗
PubMed1984

Intraventricular haemorrhage and haemostasis defects.

Twenty five of 106 preterm infants of 34 weeks' gestation or less developed intraventricular haemorrhage within the first 48 hours of life. A comparison of infants with and without intraventricular haemorrhage showed no significant differences in their haemostatic parameters at birth. At age 48 hours the group with intraventricular haemorrhage showed a prolonged activated partial thromboplastin time and reduced factor II, VII, and X activity. There was a significant correlation between the severity of intraventricular haemorrhage and the degree of haemostasis abnormality both in cord blood and in blood obtained at age 48 hours. Those infants sustaining grade IV intraventricular haemorrhage had a significantly prolonged activated partial thromboplastin time, reduced factor II, VII, and X activity; and a decreased fibrinogen concentration at birth. At age 48 hours these defects were accompanied by reduced platelet counts and an increased megathrombocyte index. Although intraventricular haemorrhage is multifactorial, we postulate that correction of haemostasis abnormalities at birth may prevent progression to more severe grades of haemorrhage.

Blood Coagulation Disorders↗
PubMed1983

An outbreak of Clostridium difficile necrotizing enterocolitis: a case for oral vancomycin therapy?

During a 2-month period, 13 infants in this neonatal intensive care unit developed necrotizing enterocolitis, increasing the prevalence in inborns from 5.2 to 20.5/1,000 live births. Fifty-seven perinatal and neonatal factors, many of which have previously been associated with necrotizing enterocolitis, were compared between the infants with necrotizing enterocolitis and 17 unaffected inborn control infants admitted concurrently. Clostridium difficile cytotoxin was detected in the stools of 12 affected infants (92.3%) in comparison with two control infants (11.8%) (P less than .001), and the organism was isolated in eight affected neonates (61.5%) compared to none of the control infants (P less than .001). The outbreak was terminated upon institution of oral vancomycin therapy in cases and infant contacts, and strict antiinfective measures in the neonatal intensive care unit. This indicates an etiologic role of C difficile in the outbreak. Oral vancomycin in the management of necrotizing enterocolitis was assessed by therapeutic response, drug levels, and occurrence of side effects. Oral vancomycin therapy is indicated in necrotizing enterocolitis outbreaks in units where C difficile is endemic.

Clostridium Infections↗
PubMed1981

Fatty acid utilization in perinatal de novo synthesis of tissues.

The fatty acid content of fetal tissues was utilized to estimate essential fatty acid accretion during intrauterine growth. These rates of essential fatty acid accretion were used to predict that 400 mg/kg of body weight for omega-6 fatty acids and 50 mg/kg of body weight for omega-3 fatty acids per day would be used for intrauterine de novo synthesis of tissues. For the high risk low birth weight infant of approx. 1300 g birthweight it can be calculated that extrauterine de novo tissue synthesis would utilize about 280 mg/kg of body weight for omega-6 fatty acids and about 35 mg/kg of body weight for omega-3 fatty acids based on projected growth rates that are similar in composition to intrauterine growth and amount to 17 g of gain per day. From fatty acid analysis of brown and white adipose tissue it was estimated that some 70 and 78% of these net whole body accretion rates for essential fatty acids represent omega-6 and omega-3 fatty acid accretion in the adipose organs. Fatty acid analysis of human milk at day 16 of lactation was utilized to estimate the low birth weight infants' daily intake of major essential and other fatty acids. For intake levels of 120 kcal/kg it was concluded that the essential fatty acid content of mothers' own milk provides 6650 +/- 345 mg of total fatty acids, 850 +/- 160 mg of omega-6 fatty acids and 140 +/- 17 mg of omega-3 fatty acids.

Adipose Tissue↗
PubMed1981

Fatty acid accretion in the development of human spinal cord.

Lumbar and cervical segments of fetal and infant spinal cord were examined to determine the deposition rate of individual fatty acids in the spinal cord during the last trimester of fetal development and first 16 weeks of life. Fatty acid accretion rates were determined by regression analysis of spinal cord fatty acids at varying developmental ages. During the last trimester of fetal growth, accretion of major tissue fatty acids occurred earlier in cervical segments of spinal cord and at a greater rate than observed in lumbar regions. Postnatal accretion of fatty acids in cervical regions of spinal cord was minimal on a per gram of tissue basis with the exception of moderate increases in total omega-9 and saturated fatty acids, reflecting myelination. Significant postnatal accretion of fatty acids in lumbar regions of the spinal cord occurred some 4 weeks postnatally at rates significantly in excess of in utero rates. These developmental changes in fatty acid accretion are quantitatively relevant to estimates of fatty acid incorporation into spinal cord and parallel known processes of myelination and increasing neuro-motor activity in the developing infant.

Fatty Acids↗
PubMed1981

Fatty acid accretion in fetal and neonatal liver: implications for fatty acid requirements.

The fatty acid content of liver was determined during the last trimester of infant growth and first 4 months of life in order to estimate fatty acid levels of developing liver and to assess minimal fatty acid requirements for tissue synthesis. Accretion rates were computed by regression analysis on fatty acid determinants of total liver lipid extracts from infants of varying developmental ages. During the last trimester of liver growth, accretion of most fatty acids paralleled increases in liver weight with the exception of C18:3, omega-3. This fatty acid remained at consistently low levels during the last trimester and represented less than 10% of total omega-3 fatty acids present in liver, even though significant accretion of longer chain omega-3 homologues occurred during the final trimester. For the term infants studied, significant increase in liver weight did not occur during the early weeks of life. However, liver levels of major fatty acids declined during the first five weeks of life apparently reflecting mobilization of saturated, omega-9 and omega-3 fatty acids from liver. During the first four months of life C18:2, omega-6 and total omega-6 fatty acid content of liver increased about 3.5- and 2-fold, respectively. After the initial 5 week lag net accretion of other fatty acid components also occurred in the developing liver. These developmental changes in fatty acid components of liver are quantitatively relevant to estimating the magnitude of the potential essential fatty acid reserve that may be present in liver of the developing human neonate.

Fatty Acids↗
PubMed1980

Macro-mineral content of milk obtained during early lactation from mothers of premature infants.

Milk from mothers giving birth prematurely was analyzed for Na, Cl, K, Mg, Ca and P concentrations. The data presented are from analyses of milk samples representative of complete 24-hour expressions and collected serially over the first 29 days of lactation from mothers giving birth at term (FT) and mothers giving birth prematurely (PT). Mineral composition of FT and PT milks was similar during the first month lactation. With the exceptions of Mg and P, the concentrations of the minerals studied were higher initially than at the end of the fourth week of lactation. From these data, intakes of premature infants fed their own mothers' milk can be estimated and compared to predicted mineral requirements for the premature infant. On the basis of this comparison, we suggest that the quantities provided of Na, Cl, K and Mg, but not Ca and P, would be adequate to meet requirements of premature infants during the early weeks of life.

Adult↗
PubMed1980

Intrauterine fatty acid accretion rates in human brain: implications for fatty acid requirements.

Fatty acid components of infant brain were determined to assess fatty acid requirements for synthesis of structural lipids in brain tissue during the last trimester of development in the fetus. Quantitative fatty acid analysis of cerebellum, frontal and occipital brain lobes indicated rapid accretion of chain elongation and desaturation products during the last trimester of brain growth. Frontal and occipital brain lobes were similar in fatty acid content. Fatty acid accretion rates were determined by regression analysis of tissue fat components at varying gestational ages. Tissue accretion of saturated and omega-9 fatty acids, as well as total fatty acid content, paralleled increases in whole brain weight. Levels of linoleic (C18:2, omega-6) and linolenic (C18:3, omega-3) acids were consistently low in brain during the last trimester of development, while marked substantial accretion of long chain desaturation products, arachidonic (C20:4, omega-6) and docosahexaenoic (C22:6, omega-3) acids occurred. Accretion of individual fatty acids of cerebellum also reflected changes in tissue total fatty acid content, with exception of the levels of C18:3, omega-3 and its chain elongation products present in cerebellum during the last trimester. These developmental changes and estimates of fatty acid incorporation into whole brain and cerebellum are quantitatively relevant to estimation of fatty acid requirements of the low birth weight neonate.

Brain↗
PubMed1980

Extrauterine fatty acid accretion in infant brain: implications for fatty acid requirements.

Total fatty acid content of infant brain was determined to assess minimal fatty acid requirements for synthesis of structural lipids in brain tissue during the first 13 weeks of life. Fatty acid accretion rates were determined by regression analysis of tissue fat components at varying postnatal ages. Quantitative fatty acid analysis indicated that postnatal accretion of long-chain polyenoic fatty acids in cerebellum, frontal and occipital brain lobes initially appeared to lag behind the rate of increase in brain weight and brain fat content. After a 4-week period total long-chain fatty acids increased at a rate similar to the increase in brain weight. Accretion of individual fatty acids in cerebellum also reflected changes in tissue total fatty acid content. These developmental changes in fatty acid components of whole brain and cerebellum are quantitatively relevant to estimation of the minimal extrauterine fatty acid requirements of the human neonate.

Brain↗
PubMed1979

Neonatal respiratory distress: potential for prevention.

A prospective study was conducted of 100 consecutive admissions to the neonatal intensive care unit of the Hospital for Sick Children, Toronto, of infants with respiratory distress syndrome or transient tachypnea of the newborn. It was found that in 15% of cases the illness was completely preventable, being the result of unintentionally premature termination of pregnancy. Significant intrapartum asphyxia occurred in 44% of the infants in whom respiratory distress syndrome developed. Factors placing the pregnancy at high risk were present antenatally in most cases, and most of the deliveries took place in hospitals without adequate facilities or staff, or both, for the requirements of the infant at and following birth.

Apgar Score↗
PubMed1979

Structural heart disease in the newborn. Changing profile: comparison of 1975 with 1965.

The earlier detection and investigation of babies with congenital structural heart disease has resulted in earlier treatment and better management of these patients. In 1965, at the Hospital for Sick Children, Toronto, 121 cases were assessed and treated; by 1975 this figure had risen to 226 cases. Few changes were noted in the incidence of the 10 most common malformations, except for the obvious increase in the incidence of patient ductus arteriosus due to survival of increasingly premature infants. The sick cardiac neonate was referred earlier in 1975, studied with newer non-invasive investigations, and, according to the severity of symptoms and signs, was sent sooner to cardiac catheterisation. 80% of babies presenting with cyanosis survived the first month and 60% of babies with congestive heart failure survived. With better surgery and perioperative care, the survival rate in the first month after surgery rose from 37% in 1965 to 70% in 1975.

Cardiac Catheterization↗
PubMed1978

Renal handling of phosphate in very low birthweight (VLBW) infants (less than 1.3 kg): effects of calcium and sodium intake.

Five patient groups of VLBW infants with the same P-intake but varying Ca and Na intake were examined as to their urinary excretion of P and Na and on their renal clearance of P. The effect of increasing the Na intake from 1.5 to 3 mEq/kg/24 h on C(P) was also examined. In the control group of infants with an intake of 210 mg Ca and 80 mg P/kg/24 h, the C(P) was significantly correlated with postnatal, but not postconceptional age. A relatively low Ca intake of 100 mg/kg/24 h led to age-related values two to three times as high, whereas Ca supplementation to a total intake of 250 mg/kg/24 h decreased the C(P) significantly. A Ca intake of 175 mg/kg/24 h led to C(P) similar to those seen with one of 100 mg/kg/24 h. Changing the Na intake from 1,5 to 3 mEq/kg/24 h did not influence the C(P). There was no correlation between UP and UNa in any of the patient groups examined.

Aging↗
PubMed1978

Neonatal transport: a controlled study of skilled assistance. Mortality and morbidity of neonates less than 1.5 kg birth weight.

To attempt to demonstrate the need for skilled care of sick neonates in transport, a modified randomized controlled study of infants being transported to this institution was carried out. Although special equipment was used, ambulances were not modified. Results of the first phase reported here show that infants weighing less than 1.5 kg at birth, transported by a trained physician and nurse, were significantly warmer, less hypotensive, and less acidotic on admission to the NICU. Mortality was significantly reduced, first week morbidity somewhat lessened, and duration of stay in hospital reduced by more than one third (P less than 0.01).

Ambulances↗