Biomedical subjects

B J Taylor

Publications and source records attributed to B J Taylor.

At least 73 records · Page 4Linked to original sources

PubMed1996

Temperature and the sudden infant death syndrome.

The relationship between the days on which sudden infant death syndrome (SIDS) occurred and daily minimum and average temperature was examined for five regions of New Zealand for a three-year period beginning on 1st November 1987. There was a marked winter excess of SIDS. After adjusting for season the temperature on the days preceding SIDS deaths were negatively associated with SIDS, but the effect was not statistically significant. Further analysis, using data from the New Zealand Cot Death Study, a nation-wide case-control study was based on the mean temperature 2 to 5 days before death for the cases or a nominated day for the controls. Statistically significant interaction effects between temperature and sleep position, and temperature and the age of the infant were found. A mean temperature 2-5 days beforehand 2.5 degrees C below that on the day of death or the nominated day increased the risk of SIDS in those sleeping prone by 1.17 [95% CI 0.95 to 1.43] and in those sleeping on their side or back by 0.96 [95% CI 0.77 to 1.19]. In the same circumstances the odds ratio (OR) for infants aged 3 months or less would increase by 0.98 [95% CI 0.80 to 1.19] and that for infants older than 3 months by 1.20 [95 CI 0.97 to 1.49]. The statistically significant negative association between temperature a few days before death and SIDS has been reported previously. Most of the effect of temperature can be attributed to seasonal variations, and minor fluctuations in day to day temperatures make only a very small contribution to SIDS.

Case-Control Studies↗

PubMed1996

Pathophysiology of overheating in a piglet model: findings compared with sudden infant death syndrome.

OBJECTIVE: To examine the nature of hyperthermia-induced pathophysiological changes in an animal model including effects on lung compliance. METHODOLOGY: Piglets were randomly assigned to heated or non-heated groups. Heated animals were warmed to 4 degrees C above normal body temperature while sedated and breathing spontaneously. Cardiorespiratory variables were recorded serially and haematological assessments and blood cultures taken at 0 and 6 h. After 6 h the animals were killed and a limited postmortem was performed. Control animals had all procedures without heating. RESULTS: Heated piglets developed tachycardia, hypotension and a metabolic acidosis in addition to tachypnoea, hypocapnic alkalosis and a neutrophil leucocytosis. Rectal temperature after death fell at the same rate in both groups. Lung histology revealed an excess of lung haemorrhage and alveolar oedema in the heated group. No significant group differences in dynamic lung compliance were demonstrated. CONCLUSIONS: The pathological changes that occur during hyperthermia are non-specific but not incompatible with those found in sudden infant death syndrome. There was no confirmation of the thesis that hyperthermia causes death by altering lung compliance.

Animals↗

PubMed1996

Symptoms, sweating and reactivity of infants who die of SIDS compared with community controls. New Zealand National Cot Death Study Group.

OBJECTIVE: To describe the symptoms of illness reported by the parents of infants who have died of sudden infant death syndrome (SIDS) compared with those reported by community controls. METHODOLOGY: A nationwide case-control study involving regions of New Zealand with 78% of all births between 1987 and 1990. Home interviews were completed with parents of 393 (81% of total) infants who died from SIDS in the post neonatal age group, and 1592 (88.4% of total) controls who were a representative sample of all hospital births in the study region. RESULTS: Symptoms of infection were common in both cases and controls, but were not significantly different. Infants dying of SIDS, however, were likely to have symptoms suggestive of more severe illness in the 2 days before death (odds ratio [OR] = 3.02, 95% confidence interval [CI] 1.69-5.38). After adjusting for potential confounding this was still statistically significant (adjusted OR 2.36, 95% Cl 1.14-4.90). Also, babies dying of SIDS were more likely to have been less reactive to their environment in the 2 weeks before death compared with the controls (univariate OR 0.88, 95% Cl 0.55- 1.39, adjusted OR 0.55, 95% CI 0.29-0.88). 'Drenching' sweats at least weekly were reported for 15.6% of case infants compared with 5.9% of control infants (adjusted OR 2.12, 95% CI 1.53-3.39). Forty per cent of these infants had this symptom in the first 4 weeks of life when it was also associated with a significantly raised risk of SIDS. Apnoea lasting more than 20 s was reported for 13.2% of case infants compared with 5.3% of control infants (adjusted OR 1.93, 95% CI 1.17-3.17). Similarly, 71.8% of case infants' faces were reported to never turn red while awake compared to 49.8% of control infants (adjusted OR 2.98, 95% CI 2.19-4.07). CONCLUSIONS: Only a small number (6.4%) of babies who die of SIDS have symptoms of serious illness in the 2 days before death. There is support for the hypothesis that there is a group of babies dying of SIDS who have subtle abnormalities in autonomic control or arousal ability.

Apnea↗

PubMed1996

Life events, social support and the risk of sudden infant death syndrome.

The effects of a lack of maternal social support and stressful life events on the risk of Sudden Infant Death Syndrome (SIDS) were examined by case-control design: 390 cases and 1592 control infants. A seven item index of mother's social support was used. A possible 21 life events experienced by each family were summed and then put into one of three categories: 0-2, 3-5, and 6 or more life events. Similar levels of maternal social support were found for both groups. SIDS families experienced significantly more stressful life events than control families, but once social factors had been taken into account this association was lost.

Analysis of Variance↗

PubMed1996

Growth and the sudden infant death syndrome.

OBJECTIVE: To compare the growth curves based on measurements of body weight for male and female infants dying of sudden infant death syndrome (SIDS) with those of male and female controls. METHODS: The data were drawn from a large case control study of SIDS carried out in New Zealand between 1987 and 1990. RESULTS: The mean birthweight for the cases was 3049 g and for the controls 3526 g. The mean growth curves for the male and female controls were close to the 50th centile of growth charts used in New Zealand. The growth curve for the male cases diverged from that of the controls, being closer to the 25th percentile. The differences between the female cases and controls were less pronounced. The differences in weekly weight increments derived from the curves for the cases and controls for nine 4-week periods were not statistically significant after taking into account race, manner of feeding and maternal smoking for any 4-week period. CONCLUSIONS: SIDS cases were lighter at birth, but their growth velocity was normal postnatally.

Body Weight↗

PubMed1996

A potential danger of bedclothes covering the face.

Investigations of infants dying unexpectedly have reported up to 28% being found completely under bedding. No detailed physiological studies looking at the possibilities of asphyxia in this situation are available. The aim was to determine the potential for asphyxia under different types and thicknesses of bedding. A mechanical model of a 3-month-old infant's respiratory system was used. Bedding was positioned over the head in a supine position, and inspired carbon dioxide recorded. With a fixed respiratory rate and tidal volume, carbon dioxide accumulation increased with increasing layers of blankets. Up to 8.3% inspired carbon dioxide was recorded with more than four layers of blankets. A cotton sheet between the face and blankets reduced the accumulation by half. An infant found dead under bedding may have been exposed to an asphyxial stress. Suffocation from rebreathing trapped, expired gases can be a cause of death in this situation.

Asphyxia↗

PubMed1996

The correlation of elevated levels of an index of lipid peroxidation (MDA-TBA) with adverse outcome in the very low birthweight infant.

The objective of this study was to examine the relationship between malondialdehyde-thiobarbituric acid (MDA-TBA) levels, as a measure of lipid peroxidation, in very low birthweight (VLBW) infants and outcome measures. A prospective observational longitudinal study was carried out in two level III neonatal units in the South Island of New Zealand measuring MDA-TBA levels in 61 VLBW infants in 1993. MDA-TBA levels were measured in (i) maternal plasma within 48 h of parturition, (ii) cord plasma, and (iii) infants' plasma at 2, 7, 14 and 28 days of age and correlated with antenatal and postnatal factors. Elevated levels of plasma MDA-TBA at 7 days were associated with adverse respiratory and ophthalmological outcome in the VLBW infants. Elevated MDA-TBA levels were measured at sample times close to the time of death in the infants who died. These results substantiate previously reported preliminary observations and support the hypothesis that oxidative injury, particularly within the first 7 days of life, is associated with the development of the long-term complications of the pre-term infant. MDA-TBA levels appear to be a useful measure to continue to explore the role of free radical mediated disease in the VLBW infant.

Fat Emulsions, Intravenous↗

PubMed1996

Thermal balance in infants.

A theoretical model of heat balance is presented that could clarify the matching of babies' wrapping with their environments. Best estimates of metabolic heat input and heat loss by all known routes are defined for 22 parts of the body surface. The variation of these with core temperature, posture, skin vasodilatation, and the onset of sweating are calculated: first, by using presumed skin temperatures and second, by following iterative calculation of the skin temperature and the consequent total heat losses. Calculation of the highest tolerable ambient temperature (HTAT) for a given set of clothes, underbedding, and covers shows that a well-wrapped baby lying face down could have an HTAT 10 degrees C lower than if he/she were lying supine. Representative values for highest and lowest tolerable temperatures (defined in text) are presented for the first 6 mo of life. Retrospective estimation of thermal balance from death-scene data on clothing and bedding can permit assessment of hyperthermia or hypothermia as a contributing cause of death. Recommendations are made on the avoidance of hyperthermia.

Age Factors↗

PubMed1996

Allergy and the risk of sudden infant death syndrome. The Members of the New Zealand Cot Death Study Group.

BACKGROUND AND OBJECTIVE: There are several sources that suggest that there is a link between allergy and sudden infant death syndrome. We endevavoured to look for evidence of an association between allergic disease and the risk of sudden infant death syndrome (SIDS). METHODS: A nationwide case-control study covering a region with 78% of all births in New Zealand during 1987-90. Interviews were completed with the parents of 393 (81.0% of total) infants who died from the sudden infant death syndrome (SIDS), and 1592 (88.4% of total) control families who were a representative sample of all hospital births in the study region. RESULTS: Eczema was reported in 13.9% control infants compared with only 8.0% of the SIDS infants, univariate odds ratio for this in terms of risk for SIDS was 0.56 (95% confidence interval 0.37, 0.84) for infants with eczema compared with those without. This lesser risk for SIDS was unchanged when adjusted for potential confounding factors. The risk of SIDS was not associated with reported cow's milk reactions or a family history of allergic symptoms once adjustments were made for possible confounding factors. CONCLUSION: Infants with skin disorders identified by their parents as eczema had a low risk for SIDS. Families can be reassured that atopy is not a risk factor for SIDS.

Asthma↗

PubMed1995

Vitamin K administration in neonates: survey of compliance with recommended practices in the Dunedin area.

AIMS: A three dose oral regimen for vitamin K prophylaxis was introduced as an alternative to a single intramuscular injection in August 1992. An assessment of the acceptance of this regimen was needed to determine if the risk of developing haemorrhagic disease of the newborn had altered. METHODS: A survey of compliance with the recommendations was made using a telephone questionnaire to 179 parents. RESULTS: One hundred and fifty three breast fed infants received oral vitamin K. Repeated doses were given to 133 (97%) of 138 breast fed infants at 1 week and 115 (94%) of 122 breast fed infants at 6 weeks. Twenty three of the infants were given the third dose of vitamin K later than recommended. CONCLUSION: Although the majority of infants received all three recommended doses, a quarter of infants given oral prophylaxis are at an increased risk of haemorrhagic disease of the newborn in our sample population.

Administration, Oral↗

PubMed1995

Tryptase immunoreactive mast cell hyperplasia in bronchopulmonary dysplasia.

Bronchopulmonary dysplasia (BPD), the most common cause of chronic lung disease in prematurely born infants, is histologically characterized by various degrees of airway and alveolar septal fibrosis. Tryptase, a serine protease specific to mast cells, has been shown to have potent fibroblast mitogenic properties and in addition has been shown to be increased in adult fibrotic lung disorders. Based on this analogy, the distribution of pulmonary mast cells exhibiting tryptase immunoreactivity was investigated by immunoperoxidase staining in autopsy specimens of infants dying with BPD. Morphologically normal lung specimens from similarly aged infants dying of sudden infant death syndrome (SIDS) served as controls. Tryptase-positive mast cell counts were performed at 250x from at least 10 random fields in bronchial, peribronchiolar, and alveolar regions. Compared to controls, in lung sections exhibiting typical histologic features of long-standing BPD, tryptase positive cells were significantly increased in bronchial (23.9 +/- 3.6 vs 14.4 +/- 2.3) and peribronchiolar (15.3 +/- 3.2 vs 4.63 +/- 0.6) regions compared to controls (P < 0.05, Student's t test). In particular, alveolar regions exhibiting moderate to severe degrees of septal fibrosis exhibited a dramatic increase in the number of tryptase-positive cells (9.83 +/- 1.89 vs 0.34 +/- 0.18, P = 0.003). These findings of a tryptase-positive mast cell hyperplasia in BPD suggest potential roles of mast cells as well as tryptase in the pathogenesis of this disease.

Age Factors↗

PubMed1995

Predicted disulfide-bonded structures for three uniquely related proteins of Plasmodium falciparum, Pfs230, Pfs48/45 and Pf12.

Pfs230 is a surface protein of the gametes of Plasmodium falciparum and has been demonstrated to be a target of malaria transmission-blocking antibodies; it is an important candidate antigen for a transmission-blocking vaccine. The target epitopes of transmission-blocking antibodies against Pfs230 are almost all reduction sensitive suggesting that disulfide bonds are critical for folding the native molecule. Following the cloning of the Pfs230 gene attempts are now underway to express subunits of the protein for use in vaccine trials. It will be important to understand the disulfide-bond structure of the Pfs230 to achieve this goal. In this paper we present a model for this structure based on the observation that the Pfs230 molecule contains a series of regularly repeated cysteine-containing motifs. Four such motifs have been identified, together with a fifth cysteineless motif, which occur in the same relative order, with regular alternating omission of specific motifs, 14 times throughout the length of the protein. Each of the 14 sets of motifs contains an even number of cysteine residues (2, 4 or 6). We postulate that each set folds into a separate disulfide-bonded domain in which corresponding pairs of cysteines form an equivalent disulfide bond in every such domain. The postulated bonding arrangements in the different domains are mutually confirmatory throughout the sequence of Pfs230. We have identified two other malaria proteins, Pfs48/45 and Pf12, which share the same arrangements of motifs and conform to the same disulfide-bond structure proposed for Pfs230; no other proteins in the sequence data base share these characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Effects of parenteral L-carnitine supplementation on fat metabolism and nutrition in premature neonates.

The effects of parenteral L-carnitine supplementation on fat metabolism, nutrient intake, and plasma and erythrocyte carnitine concentrations were studied in 43 very low birth weight infants. Infants were randomly assigned to control or carnitine-supplemented (50 mumol/kg per day) groups within two weight categories: group 1, 750 to 1000 gm, and group 2, 1001 to 1500 gm. Plasma total, free, and acyl carnitine levels, erythrocyte carnitine levels, serum beta-hydroxybutyrate and triglyceride levels, and total fat intake were monitored weekly until 50% of total caloric intake was met enterally. Neonates receiving carnitine had higher plasma carnitine levels than control groups (total carnitine: group 1, 75.2 +/- 22.9 vs 9.6 +/- 2.7 mmol/ml; group 2, 61.6 +/- 31.2 vs 13.0 +/- 9.2 nmol/ml). Levels of beta-OH-butyrate decreased from baseline in control neonates (group 1, 0.12 +/- 0.06 to 0.03 +/- 0.02 mmol/L; group 2, 0.11 +/- 0.03 to 0.05 +/- 0.02 mmol/L); they remained unchanged in supplemented groups. Thus ketogenesis appeared less impaired in infants receiving supplements. Supplemented group 2 tolerated more fat than control group 2; triglyceride levels remained acceptable in all groups. Carnitine group 2 had greater weight gain than control group 2 during the first 2 weeks of life. We conclude that very low birth weight infants requiring prolonged parenteral nutrition have carnitine deficiency with impaired ketogenesis. Parenteral administration of carnitine appears to alleviate this metabolic disturbance.

Carnitine↗

PubMed1995

Antenatal and intrapartum factors associated with sudden infant death syndrome in the New Zealand Cot Death Study.

OBJECTIVE: To describe the relationship between antenatal and intrapartum factors and sudden infant death syndrome (SIDS). METHODOLOGY: The New Zealand Cot Death Study was a 3 year case-control study, with 485 infants who died from SIDS in the postneonatal period and 1800 randomly selected control infants. Data were obtained from obstetric records, parental interview and community nursing records. RESULTS: This study confirms many of the antenatal and intrapartum risk factors for SIDS noted in studies from both the southern and northern hemispheres. After controlling for potential confounders, such as occupational group and marital status, significant inverse effects were noted for interpregnancy interval, birthweight and gestation. Other factors that retained a significantly increased risk of SIDS were: increasing parity, bacteriological evidence of urinary tract infection (UTI) (adjusted odds ratio 1.73, 95% CI 1.10-2.73); smoking antenatally (AdjOR 2.14, 95% CI 1.61-2.84); less than six antenatal checks attended (AdjOR 1.84, 95% CI 1.19-2.84); second stage of labour less than 16 min (AdjOR 2.06, 95% CI 1.35-3.14) and multiple birth (AdjOR 3.23, 95% CI 1.70-6.02). No interaction was observed between maternal haemoglobin and antenatal smoking. Interactions were tested for and not found between antenatal smoking and three antenatal risk factors (UTI, short second stage of labour and number of antenatal appointments). The only significant interaction between these three factors and three modifiable postnatal risk factors (prone sleeping, bed sharing and bottle feeding) was between bed sharing and fewer antenatal appointments. The risk of SIDS associated with bed sharing was greater among those whose mothers had fewer antenatal appointments. CONCLUSIONS: Although many of the previously identified antenatal and intrapartum risk factors for SIDS are confirmed, the risks of SIDS associated with obstetric factors are in general considerably lower than the risks associated with the four modifiable postnatal risk factors.

Case-Control Studies↗

PubMed1995

Sudden infant death syndrome in New Zealand: are risk scores useful? New Zealand National Cot Death Study Group.

STUDY OBJECTIVE: To evaluate the Christchurch, Invercargill, Dunedin (CID) and Oxford record linkage study (ORLS) risk scores in five regions of New Zealand and examine the effect of risk factors for sudden infant death syndrome (SIDS), such as prone sleeping position, maternal smoking, breast feeding, measures of illness, the use of antenatal classes, community health care, and medical services on a high and low risk group delineated by the CID score. DESIGN: This was a case-control study of infants dying of SIDS. SETTING: Both the cases and controls were born in one of five health districts in New Zealand and their parents were interviewed between 1 November 1987 and 31 October 1990. PARTICIPANTS: The cases were 485 infants who died of SIDS. The controls were a random sample drawn from the same five regions in which the cases were born, chosen so that their age on the day on which they were interviewed was similar to the age at death of the cases. Risk scores were calculated for 387 case and 1579 controls. MEASUREMENTS AND MAIN RESULTS: Using the recommended cut off points the sensitivity and specificity of the CID and ORLS were found to be similar to those described for other samples. The differences among the regions were significant. There was, however, no evidence that the association between SIDS and the risk factors considered was different in the high and low risk groups delineated by the CID score. The relative attributable risk for smoking was 32.3% in the high risk group. The excess risk that could be attributed to a different prevalence of any of the other risk factors in the high risk group was small when compared with the low risk group. CONCLUSIONS: Health care resources should be spent on promoting and evaluating good child care practices for all, rather than identifying and promoting special interventions for those in the high risk category.

Breast Feeding↗

PubMed1995

Sex-specific differentiation of a male-specific abdominal muscle, the Muscle of Lawrence, is abnormal in hydroxyurea-treated and in fruitless male flies.

A prominent sex-specific abdominal muscle in male Drosophila is the Muscle of Lawrence (MOL), which is induced by male-specific innervation. We have examined MOL development in wild-type males, in males fed hydroxyurea to ablate the muscle precursors and in fruitless mutants, in which the MOL muscle develops aberrantly. One striking feature of MOLs in wild-type males was the presence of additional muscle nuclei compared with neighboring muscles or MOL-homologues in females. We tested whether muscle length and the sex-specific expression of a reporter gene depended critically on the number of nuclei present within a MOL fiber. MOL fibers developing from a reduced myoblast pool in hydroxyurea-affected hemisegments were recognizable by their attachment points and still contained more nuclei than did neighboring medial fibers, suggesting that these MOL fibers were able to actively recruit myoblasts nearly as well as wild-type MOLs. However, many of the hydroxyurea-affected MOL fibers were incapable of the normal male-specific expression of a muscle-specific reporter gene. We suggest that early events in MOL development, such as finding the correct muscle attachment points, are relatively insensitive to the number of MOL nuclei compared with later events, such as the sex-specific expression of a reporter gene. In fruitless mutant males, MOL-position fibers are smaller and had substantially fewer nuclei compared to wild-type MOLs. Since the number and distribution of muscle precursors was the same in fruitless mutant and wild-type animals, we propose that one fru+ function is to direct the male-specific recruitment of myoblasts into MOL-myotubes. However, fruitless+ must have more than one role in MOL fiber development, since simple reduction in the number of muscle nuclei, as demonstrated by the hydroxyurea ablations, is insufficient to account for all of the MOL muscle phenotypes in fruitless mutant males.

Abdominal Muscles↗

PubMed1995

The relationship of selenium status to respiratory outcome in the very low birth weight infant.

OBJECTIVE: To examine the relationship between plasma and erythrocyte selenium and glutathione peroxidase (GPx) levels in premature infants and outcome measures. DESIGN: Prospective observational longitudinal study. SETTING: Two regional neonatal intensive care units in the South Island of New Zealand, an area with low soil selenium. PATIENTS: Seventy-nine infants with birth weights less than 1500 g or gestation less than 32 weeks admitted within 48 hours of birth from November 1992 through November 1993. MAIN OUTCOME MEASURES: Oxygen requirement at 28 days (chronic lung disease), or 36 weeks postmenstrual age and for all or most of the time from birth (bronchopulmonary dysplasia), total days in oxygen, retinopathy of prematurity, periventricular hemorrhage, or ventricular dilatation. RESULTS: Initial infant plasma selenium and GPx levels were about two thirds of maternal levels and fell a further 30% in 28 days. In contrast to adults, there was a poor correlation in infant plasma between selenium and GPx at birth and 28 days. Plasma selenium at 28 days was significantly lower in infants with chronic lung disease and bronchopulmonary dysplasia. After controlling for gestational age and age when fully fed orally, 28-day plasma selenium was significantly associated with the log of total days of oxygen requirement, each drop of 0.1 mumol/L in 28-day selenium being associated with a 58% increase in days of oxygen dependency. No significant associations of other parameters of selenium status and respiratory outcome were found, and there were no significant associations of any parameters of selenium status with other outcome measures. CONCLUSIONS: This study demonstrates for the first time in human infants that low plasma selenium levels are significantly associated with an increased respiratory morbidity. Whether selenium deficiency is etiologically important in determining the respiratory outcome or the result of sickness in the infant should be investigated in a randomized, controlled trial.

Bronchopulmonary Dysplasia↗

PubMed1995

Inter-hospital transport of neonatal patients on extracorporeal membrane oxygenation: mobile-ECMO.

OBJECTIVE: To describe the equipment, personnel requirements, training, management techniques, and logistic problems encountered in the design and implementation of a mobile extracorporeal membrane oxygenation (ECMO) program. DESIGN: This is a report of a technique for the transport of patients on ECMO and a description of our retrospective case series. SETTINGS: The study was conducted at a regional referral children's hospital and ECMO unit. PATIENTS: Thirteen neonatal medical patients with acute respiratory failure were transported with mobile-ECMO. RESULTS: Over a 24-month period, we transported 13 neonatal patients with mobile-ECMO. The reason for transport with mobile-ECMO was inability to convert from high-frequency ventilation (4 of 13), patient already on ECMO (1 of 13), and patient deemed too unstable for conventional transport (8 of 13). Eleven of the 13 patients were transported from other ECMO centers. Of the 13, 9 survived. No major complications during transport were reported for any of the patients. Follow-up data were available on all nine survivors of neonatal mobile-ECMO. Eight of these had normal magnetic resonance imaging scans of the brain; the ninth had a small hemorrhage in the left cerebellum. CONCLUSION: Our limited series shows that patients can be safely transported with mobile-ECMO. This program does not replace the early appropriate transfer for ECMO-eligible patients to an ECMO center.

Arkansas↗