Rebreathing from sheepskins.
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Bedding and Linens↗
Biomedical subjects
B J Taylor
Publications and source records attributed to B J Taylor.
Management of epilepsy in childhood.
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Adaptation, Psychological↗
Effect of gamma irradiation of red blood cell units on T-cell inactivation as assessed by limiting dilution analysis: implications for preventing transfusion-associated graft-versus-host disease.
Transfusion-associated graft-versus-host disease can be prevented by treating cellular blood products with gamma irradiation. A wide range of gamma irradiation dose levels has been used in routine practice. We used limiting dilution analysis, which measures clonable T cells, to assess the influence of 500 to 3,000 cGy of gamma irradiation delivered from a 137Cs source on T cells when delivered in situ to ADSOL-preserved red blood cell (RBC) units in blood bags. In a series of experiments using RBC units irradiated within 24 hours after collection, 1,500 cGy inactivated > 4 log10 of T cells; however, viable T cells were detected in all experiments. With 2,000 cGy, a > or = 4.7 log10 decrement in T-cell growth occurred in 7 of 8 experiments. With 2,500 or 3,000 cGy, no T-cell growth (> 5 log10 depletion) was detected. Comparable effects were observed with ADSOL-preserved RBC units in the standard PL 146 plastic container and in the recently developed PL 2209 plastic container. T-cell inactivation, as a function of gamma irradiation dose, was similar when either a 137Cs or a linear accelerator source was used. T cells isolated from ADSOL-preserved RBC units after storage for 7 and 21 days, although reduced in number as compared with a fresh unit stored for 24 hours, were viable, capable of proliferation, and susceptible to inactivation by gamma irradiation. Using a sensitive in vitro assay for T-cell proliferation, we found that a gamma irradiation dose of 2,500 cGy may be required to completely inactivate T cells in RBC units.
Adult↗
Behavioral and neurobiological implications of sex-determining factors in Drosophila.
The function of the central nervous system as it controls sex-specific behaviors in Drosophila has been studied with renewed intensity, in the context of genetic factors that influence the development of sexually differentiated aspects of this insect. Three categories of genetic variations that cause anomalies in courtship and mating behaviors are discussed: (1) mutants isolated with regard to courtship defects, of which putatively courtship-specific variants such as the fruitless mutant are a subset; (2) general behavioral and neurological variants (including sensory and learning mutants), whose defects include subnormal reproductive performance; and (3) mutations of genes within the sex-determination regulatory hierarchy of Drosophila, the analysis of which has included studies of reproductive behavior. Recent studies of mutations in two of these categories have provided new insights into the control of neuronally based aspects of sex-specific behavior. The doublesex gene, the final factor acting in the sex-determination hierarchy, had been previously thought to regulate all aspects of sexual differentiation. Yet, it has been recently shown that doublesex does not control at least one neuronally-determined feature of sex-specific anatomy--a muscle in the male's abdomen, whose normal development is, however, dependent on the action of fruitless. These considerations prompted us to examine further (and in some cases re-examine) the influences exerted by sex-determination hierarchy genes on behavior. Our results--notably those obtained from assessments of doublesex mutations' effects on general reproductive actions and on a particular component of the courtship sequence (male "singing" behavior)--lead to the suggestion that there is a previously unrecognized branch within the sex-determination hierarchy, which controls the differentiation of the male- and female- specific phenotypes of Drosophila. This new branch separates from the doublesex-related one immediately before the action of that gene (just after transformer and transformer-2) and appears to control as least some aspects of neuronally determined sexual differentiation of males.
Animals↗
Well health care and the sudden infant death syndrome.
The aim of this study was to examine whether poor attendance at routine antenatal and postnatal 'well child' health services was associated with a higher risk of sudden infant death syndrome (SIDS, or cot death). A nationwide case-control study of SIDS in New Zealand enrolled 485 postneonatal deaths due to SIDS and 1800 control infants who were selected randomly. The risk for SIDS was found to be higher for infants whose mothers attended their first antenatal check later than 3 months into the pregnancy, made fewer antenatal visits, and did not go to antenatal education classes. However, this increased risk was largely explained by high parity, maternal smoking, the mother not being married, mother being < 20 years old at the birth of her first child, and delivery during the winter months. Infants not attending a 6 week postnatal check had an almost three-fold increased risk of SIDS compared with those who did attend (odds ratio [OR] 2.86; 95% confidence interval [CI] 1.93, 4.24). Similarly, infants not attending well child clinics were at increased risk of SIDS (OR 2.75; 95% CI 2.09, 3.62). These differences persisted when adjusted for likely confounders. This study demonstrates that infants who miss child health nurse clinics are those most at risk for SIDS and are those who warrant increased surveillance.
Case-Control Studies↗
The micro-environment of the sleeping newborn piglet covered by bedclothes: gas exchange and temperature.
This study followed the thermal and gaseous micro-environment of the newborn piglet sleeping under two levels of bedding insulation. After 1 h in the piglet's thermal comfort zone, the head of each piglet was covered for 2 h with bedding either 12 mm or 21 mm thick. Body temperature rose rapidly, but the arterial gases showed no change in the direction of asphyxia; with the thicker covering PaO2 was unchanged and PaCO2 fell and pH rose. These changes were despite a small rise in environmental PCO2 and fall in PO2 but were also minimized by the piglet's ability to avoid profound hypocapnia by panting at a very low tidal volume. No significant changes in blood gases occurred with the thinner bedding; the temperature rose markedly but more slowly. It is suggested that human babies submerged under bedclothes for any length of time would be more likely to succumb to the effects of hyperthermia than of asphyxia.
Animals↗
Factors adversely associated with breast feeding in New Zealand.
Control data from 1529 infants studied in a multicentre case-control study of sudden infant death in New Zealand were analysed to identify factors that might hinder the establishment and duration of breast feeding. Although 1300 infants (85%) were exclusively breast-fed at discharge from the obstetric hospital, this fell to 940 (61%) by 4 weeks. Logistic regression was used to identify factors that might adversely influence breast feeding 'at discharge', 'at 4 weeks' and the overall 'duration' of breast feeding. When adjusted for confounding factors, not exclusive breast feeding 'at discharge' was significantly associated with: twin pregnancy, being a Pacific Islander, mother not bedsharing, subsequent dummy use, birthweight less than 2500 g, heavy maternal smoking, not attending antenatal classes and mother less than 20 years old at first pregnancy. Mothers smoking more than 20 cigarettes a day were nearly twice as likely to not exclusively breast feed on discharge compared to those who did not smoke. A 'dose response' was apparent with the heaviest smokers having the least likelihood of establishing exclusive breast feeding. Being exclusively breast-fed at discharge but not 'at 4 weeks' was associated with: twin pregnancy, admission to a neonatal intensive care unit, subsequent dummy use and not being married. A shorter overall 'duration' of breast feeding was associated with maternal smoking, subsequent dummy use, mother not bedsharing, twin pregnancy, mother less than 20 years old at first pregnancy, low occupational status and not attending antenatal classes. These effects persisted when social and demographic factors, including birthweight, were taken into account.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Clothing and bedding and its relevance to sudden infant death syndrome: further results from the New Zealand Cot Death Study.
As part of a large nationwide case-control study covering a region with 78% of all births in New Zealand during 1987-90, the clothing and bedding of infants dying of sudden infant death syndrome (SIDS) and that of an appropriate control group were recorded. Cases consisted of 81% (n = 393) of all cases of SIDS in the study area and 88.4% (n = 1592) of 1800 control infants randomly selected from the hospital births and who completed a home interview. Use of a wool 'waterproof' underblanket was associated with a significantly reduced risk of SIDS (adjusted OR 0.44; 95% CI: 0.26-0.73) while sheepskin use was not. Firm tucking was identified as contributing to a reduced risk of SIDS even after adjusting for potentially confounding variables (adjusted OR 0.63, 95% CI: 0.46-0.86). Sixty case infants (15.6% of cases) were found dead with the head covered but there were no equivalent data for controls. Having been found previously completely covered by bedding was equally common in cases and controls (28.8% cases and 30.6% of control infants). Other differences of bedding and clothing between cases and controls were small; mattress characteristics were not studied. The exact methods in which babies are cared for are important and this study suggests that infants are at lower risk of SIDS when firmly tucked in and when sleeping on a 'waterproof' wool underblanket.
Bedding and Linens↗
Travel and changes in routine do not increase the risk of sudden infant death syndrome.
We investigated the relationship between travel and changes in routine and the sudden infant death syndrome (SIDS) among 485 SIDS cases compared with 1800 randomly selected control infants. There was no increased risk of SIDS with travel. Special events, such as christenings, were not associated with an increased risk of SIDS. However, visits to and by friends or relatives were associated with a significantly reduced risk of SIDS after controlling for potential confounders (odds ratios = 0.70; 95% confidence interval = 0.52, 0.96). These findings may indicate less social support in SIDS cases.
Analysis of Variance↗
Lipid peroxidation as a measure of oxygen free radical damage in the very low birthweight infant.
(ABSTRACTOxygen free radical mediated tissue injury is implicated as a major factor in the pathogenesis of the long term complications seen in the premature infant, and direct evidence of their role in the development of these long term problems is lacking. A prospective observational study of 78% of very low birthweight infants admitted to a level III neonatal intensive care unit in 1992 was undertaken to determine the relationship between lipid peroxidation products, antioxidant activity, and outcome. Lipid peroxidation (malondialdehyde-thiobarbituric acid, MDA-TBA) and antioxidant activity (vitamin E and glutathione peroxidase activity) were measured in 22 very low birthweight infants in the cord blood and the infant's blood at 24 hours, 48 hours, and 1 week of age and correlated with outcome measures. The normal range for these measures was established in the cord blood samples of 48 consecutive healthy full term infants. The concentration of MDA-TBA at 1 week correlated with the number of days of oxygen treatment and number of days of positive pressure ventilatory support. Controlling for gestational age and antenatal complications simultaneously the MDA-TBA concentration remained significantly associated with the number of days of oxygen treatment and the number of days of positive pressure ventilatory support. Glutathione peroxidase was low in the premature and full term infants consistent with the low concentrations of selenium known to be present in southern New Zealand. There was evidence of a quadratic relationship between vitamin E at 1 week and the total number of days of supplementary oxygen requirement, with both high and low values associated with increased oxygen requirement. This association, however, did not remain after controlling for gestational age and antenatal complications. These results support the role of oxygen free radicals in mediating tissue damage associated with the development of chronic lung disease in the premature infant.
Chronic Disease↗
The effect of on-site extracorporeal membrane oxygenation on the therapy choice and outcomes of neonates with persistent pulmonary hypertension.
The effect of on-site extracorporeal membrane oxygenation (OS-ECMO) and selection criteria on the utilization rate of this technology is unknown. We retrospectively studied 55 neonates who were admitted to Arkansas Children's Hospital from 1985 to 1993. We compared the ECMO utilization, mortality, and morbidity rates for outborn neonates with moderate and severe persistent pulmonary hypertension (PPHN) before and after the establishment of an ECMO program with guidelines for its use at our institution. The rate of ECMO use was three times higher and the mortality rate was 13 times lower in the period after OS-ECMO compared with the period when ECMO was available only at other institutions. No differences were observed in the morbidity rates between the two periods. Physician decisions to initiate ECMO involved more than guidelines, since 37% of the increased ECMO use was not associated with use of the guidelines. Possible reasons for noncompliance with the guidelines are discussed. Neonates who had received medical therapy only and who had an oxygenation index > or = 30 and < 40 had no mortality. Our findings suggest that the need for ECMO in this group of neonates is low.
Acute Disease↗
Bed sharing, smoking, and alcohol in the sudden infant death syndrome. New Zealand Cot Death Study Group.
OBJECTIVES: To investigate why sharing the bed with an infant is a not consistent risk factor for the sudden infant death syndrome in ethnic subgroups in New Zealand and to see if the risk of sudden infant death associated with this practice is related to other factors, particularly maternal smoking and alcohol consumption. DESIGN: Nationwide case-control study. SETTING: Region of New Zealand with 78% of all births during 1987-90. SUBJECTS: Home interviews were completed with parents of 393 (81.0% of total) infants who died from the sudden infant death syndrome in the postneonatal age group, and 1592 (88.4% of total) controls who were a representative sample of all hospital births in the study region. RESULTS: Maternal smoking interacted with infant bed sharing on the risk of sudden infant death. Compared with infants not exposed to either risk factor, the relative risk for infants of mothers who smoked was 3.94 (95% confidence interval 2.47 to 6.27) for bed sharing in the last two weeks and 4.55 (2.63 to 7.88) for bed sharing in the last sleep, after other confounders were controlled for. The results for infants of non-smoking mothers were inconsistent with the relative risk being significantly increased for usual bed sharing in the last two weeks (1.73; 1.11 to 2.70) but not for bed sharing in the last sleep (0.98; 0.44 to 2.18). Neither maternal alcohol consumption nor the thermal resistance of the infant's clothing and bedding interacted with bed sharing to increase the risk of sudden infant death, and alcohol was not a risk factor by itself. CONCLUSION: Infant bed sharing is associated with a significantly raised risk of the sudden infant death syndrome, particularly among infants of mothers who smoke. The interaction between maternal smoking and bed sharing suggests that a mechanism involving passive smoking, rather than the previously proposed mechanisms of overlaying and hyperthermia, increases the risk of sudden infant death from bed sharing.
Adult↗
Ethnic differences in mortality from sudden infant death syndrome in New Zealand.
OBJECTIVES: To examine the factors which might explain the higher mortality from sudden infant death syndrome in Maori infants (7.4/1000 live births in 1986 compared with 3.6 in non-Maori children). DESIGN: A large nationwide case control study. SETTING: New Zealand. 485 infants who died of sudden infant death syndrome were compared with 1800 control infants. There were 229 Maori and 240 non-Maori cases of sudden infant death syndrome (16 cases unassigned) and 353 Maori and 1410 non-Maori controls (37 unassigned). RESULTS: Maori infants had 3.81 times the risk (95% confidence interval 3.06 to 4.76) of sudden infant death syndrome compared with non-Maori infants. The risk factors for sudden infant death syndrome within groups were remarkably similar. When Maori and non-Maori controls were compared the prevalence of many of the known risk factors was higher in Maori infants. In particular, mothers were socioeconomically disadvantaged, younger, and more likely to smoke and their infants were of lower birth weight and more likely to share a bed with another person. Multivariate analysis controlling for potential confounders found that simply being Maori increased the risk of sudden infant death syndrome by only 1.37 (95% CI = 0.95 to 2.01), not statistically significantly different from 1. Population attributable risk was calculated for prone sleeping position, maternal smoking, not breast feeding, and infants sharing a bed with another person. In total these four risk factors accounted for 89% of deaths from sudden infant death syndrome in Maori infants and 79% in non-Maori infants. CONCLUSION: The high rate of sudden infant death syndrome among Maori infants is based largely on the high prevalence in the Maori population of the major risk factors. Other risk factors, not related to ethnicity, probably explain remaining differences between Maori and non-Maori children.
Birth Weight↗
Mobile extracorporeal membrane oxygenation.
Transport of critically ill neonates in need of extracorporeal membrane oxygenation can be risky. Their extreme cardiorespiratory instability may delay or even preclude conventional transport to an extracorporeal membrane oxygenation center. We report the use of a UH-1 helicopter specially adapted for mobile extracorporeal membrane oxygenation support to transport a critically ill neonate.
Acidosis↗
Breastfeeding and the risk of sudden infant death syndrome.
The New Zealand Cot Death Study, a multicentre case-control study, was set up to identify risk factors associated with sudden infant death syndrome (SIDS). In the 3 years of the study there were 485 infant deaths classified as SIDS in the study areas and 1800 infants who were randomly selected as controls. Data were collected by parent interviews and from obstetric notes. A full set of data for this analysis was available from 356 cases and 1529 control infants. The relationship between length of any breastfeeding and SIDS was examined: 92% of the controls were initially breastfed compared to 86% of the cases. As time went by, cases stopped breastfeeding sooner than controls: by 13 weeks, 67% controls were breastfed versus 49% cases. A reduced risk for SIDS in breastfed infants persisted during the first 6 months after controlling for confounding demographic, maternal and infant factors. Infants exclusively breastfed 'at discharge from the obstetric hospital' (odds ratio [OR] = 0.52, 95% confidence interval (CI): 0.35-0.71) and during the last 2 days (OR = 0.65, 95% CI: 0.46-0.91) had a significantly lower risk of SIDS than infants not breastfed after controlling for potential confounders. We have shown a substantial association of breastfeeding with a lowered risk for SIDS. This supports the need for more positive promotion and active community support to further enhance the level and length of exclusive breastfeeding.
Breast Feeding↗
Sleep state organization in the developing piglet during exposure to different thermal stimuli.
Sleep state changes in response to different thermal stimuli were investigated in newborn piglets between 2 and 10 days of age. Test animals were exposed to cold air (7-12 degrees C) and warm air (27-33 degrees C) around the face, while the remainder of the body was kept at first warm (normothermic) then hyperthermic. A separate group of animals was studied under normothermic conditions (control) for the duration of the study. Piglets showed typical changes in sleep state patterns characteristic of rapid maturation over the first 10 days of development. It was found that both the amount of rapid eye movement (REM) sleep and, in some cases, the duration of REM episodes increased in response to facial cooling regardless of rectal temperature. However, hyperthermia with warm air exposure caused a significant decrease in the amount of REM sleep but not in the duration of REM episodes. It is suggested that an infant placed to bed in a cold room or exposed to a draft might also experience a greater amount of REM sleep than an infant placed to sleep in a warm draft-free room.
Analysis of Variance↗
Effects of dopexamine on hemodynamics and oxygen consumption after beta blockade in lambs.
OBJECTIVES: Dopexamine is a synthetic catecholamine with predominantly beta 2 and dopaminergic adrenergic receptor activities. We investigated its effects on systemic and myocardial hemodynamics and oxygen consumption (VO2) in a newborn species and studied its predominant mechanism of action. DESIGN: Prospective dose-response study with each animal serving as it own control. SUBJECTS: Eight chronically instrumented, unanesthetized lambs, 9 to 11 days of age. INTERVENTIONS: After surgical instrumentation and recovery for 72 hrs, animals were infused with dopexamine at increasing doses (1, 10, and 100 micrograms/kg/min) for 5 mins each before and after beta 1 (metoprolol) and beta 1, beta 2 (propranolol) adrenergic receptor blockade. All studies were performed during normoxia. MEASUREMENTS AND MAIN RESULTS: Heart rate (HR) increased with increasing infusion rates of dopexamine and systemic arterial pressure and vascular resistance decreased. Cardiac index, left ventricular pressure development, and systemic VO2 were unchanged, as was the rate x pressure product. Left circumflex coronary artery blood flow and myocardial VO2 were unaltered. After beta 1-blockade, dopexamine produced an increase in HR and decreased systemic arterial pressure and vascular resistance. After beta 1-adrenergic receptor blockade, no change was noted in systemic or myocardial VO2, coronary blood flow, or rate x pressure product. After beta 1, beta 2-blockade with propranolol, increasing infusion rates of dopexamine resulted in decreases in systemic pressure and vascular resistance. CONCLUSIONS: Dopexamine produced significant cardiovascular effects mediated primarily by beta 2-adrenergic receptors, and also produced residual peripheral arterial vasodilation after combined beta 1- and beta 2-blockade. The latter finding suggests that dopaminergic receptor stimulation may partly mediate dopexamine's effects in newborn lambs.
Animals↗