Prenatal nutrition counseling: two caveats.
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Birth Weight↗
Biomedical subjects
G T Ellison
Publications and source records attributed to G T Ellison.
Medical aid and racial bias in caesarean section rates.
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Cesarean Section↗
Desegregating health statistics and health research in South Africa.
OBJECTIVE: This article aims: (i) to re-examine the use and usefulness of categorisation based on 'race', ethnicity and 'population group' membership in public health research; and (ii) to assess the consequences of using these categories for describing, analysing and redressing disparities in health within South Africa. The utility of categorisation based on 'race', ethnicity and 'population group'. Categorising populations and comparing patterns of disease between different groups of people can be a useful technique for identifying potential causes of disease. In this context, ethnicity is a valid social concept that could be used to investigate the consequences of self-ascribed identity on health. Likewise, 'population group', as defined during apartheid in South Africa, represents a valid political concept that could be used for assessing the impact of social discrimination on health. However, both these concepts are often seen, and used, as euphemisms for 'race', even though there are no genetically distinct human subspecies that can be identified and categorised as discrete 'races'. Indeed, 'race' as a biological concept has no validity in human biology. Nevertheless, categories based on 'race', ethnicity and 'population group; continue to be used in health research, and reinforce the perception that differences in disease between different 'racial', ethnic and 'population' groups are the result of heritable biological characteristics. In so doing, they undermine support for health interventions that would otherwise address the social and political origins of 'racial' and ethnic disparities in health. The utility of 'population group' for redressing the consequences of apartheid. Despite these problems, 'population group' classification provides important information for assessing the impact of apartheid on disparities in health within South Africa. Yet, the abolition of apartheid legislation is likely to result in extensive socio-economic and geographical migration that will weaken the sensitivity and specificity of 'population group' as an indicator for identifying inequalities in health. For this reason, targeting corrective action at specific population groups in order to tackle disparities in health, runs the risk of ignoring alternative social causes of inequalities in health, and ignoring disadvantaged individuals from elsewhere in the population. The continued use of 'population group' classification might also perpetuate the root cause of disparities in health, by maintaining the process used to formalise discrimination. CONCLUSION: If the purpose of health research is to monitor inequalities in health and to help target resources aimed at reducing these inequalities, then it should seek, in its language, concepts and methods to undermine the root cause of disadvantage. Health research aimed at monitoring and redressing the consequences of social disadvantage on health should therefore focus on non-biological determinants of social disparities in health. As a general rule, health researchers should avoid using categories based on 'race', ethnicity and 'population group' when collecting and analysing health data; journal editors should not accept articles that use these categories without justification; and health authorities should not collect data routinely segregated by 'race', ethnicity or 'population group'.
Bias↗
Is nest building an important component of thermoregulatory behaviour in the pouched mouse (Saccostomus campestris)?
The thermoregulatory significance of nest building in Saccostomus campestris was investigated by examining the effect of temperature and photoperiod on the size and thermal conductance of nests built within artificial burrows by pouched mice from four localities in southern Africa that experience contrasting thermal conditions. There was no correlation between the amount of nesting material used and the thermal conductance of nests, which indicates that nest size was not a reliable measure of nest quality. For this reason, the significant interactive effect of sex and locality on the quantity of nesting material used, and the significantly larger nests built by wild-caught animals, appear to be unrelated to differences in nesting ability, particularly as there were no similar differences in the thermal conductance of nests between these groups. Several animals blocked the entrance to their artificial burrows and caused a significant reduction in the rate of heat loss from nests therein. However, heat conservation may not have been the primary function of plugging burrow entrances because this did not occur more frequently at lower temperatures and was not more common among animals from cooler localities. Instead, animals that sealed the entrance to their burrows were found to hoard significantly more food than animals that left the entrance open, which suggests that burrows may have been blocked to prevent the potential theft of stored food. Despite substantial variability in both the size and thermal conductance of nests built throughout the present study, there was no significant effect of temperature, photoperiod, or locality on these characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Interactive effects of temperature and photoperiod on the daily activity and energy metabolism of pouched mice (Saccostomus campestris: Cricetidae) from southern Africa.
The daily activity and energy metabolism of pouched mice (Saccostomus compestris) from two localities in southern Africa was examined following warm (25 degrees C) and cold (10 degrees C) acclimation under long (LD 14:10) and short (LD 10:14) photoperiod. There was no differential effect of photoperiod on the daily activity or metabolism of pouched mice from the two localities examined, which suggests that reported differences in photoresponsivity between these two populations were not the result of differences in daily organisation. Nevertheless, there was a significant increase in metabolism at 10 degrees C, irrespective of photoperiod, even though seven cold-acclimatized animals displayed bouts of spontaneous torpor and saved 16.4-36.2% of their daily energy expenditure. All but one of these bouts occurred under short photoperiod, which suggests that short photoperiod facilitated the expression of torpor and influenced the daily energy metabolism of these individuals. As expected for a nocturnal species, the amount of time spent active increased following acclimation to short photoperiod at 25 degrees C. However, there was a reduction in mean activity levels under short photoperiod at 10 degrees C, possibly because the stimulation of activity by short photoperiod was masked by a reduction in activity during bouts of spontaneous torpor. Cold temperature clearly had an overriding effect on the daily activity and metabolism of this species by necessitating an increase in metabolic heat production and eliciting spontaneous torpor which over-rode the effect of short photoperiod on activity at an ambient temperature of 10 degrees C.
Activity Cycles↗
The relative importance of photoperiod and temperature as cues for seasonal acclimation of thermoregulation in pouched mice (Saccostomus campestris: Cricetidae) from southern Africa.
The effect of short photoperiod and cold on metabolism and thermoregulation was investigated in pouched mice (Saccostomus campestris: Cricetidae) from three localities in southern Africa which experience contrasting climatic conditions. Mice were initially acclimated to long photoperiod (14L: 10D) at 25 degrees C, followed first by a decline in photoperiod (to 10L: 14D) and then by a fall in temperature (to 10 degrees C). Minimum observed metabolic rate (identical to basal metabolic rate) was unaffected by the decline in photoperiod but increased significantly following cold acclimation. Because minimal thermal conductance remained constant throughout the study the increase in minimum observed metabolic rate caused a decline in lower critical temperature to around 26 degrees C. In contrast to minimum observed metabolic rate, regulatory non-shivering thermogenesis improved significantly following the decline in both photoperiod and temperature. However, pouched mice from the warmest locality were significantly less responsive to photoperiod than those from the other two localities whose survival might depend upon their ability to accurately predict seasonal changes in temperature. Neither photoperiod nor temperature had any effect on body mass, yet pouched mice from the most arid locality, where food supply might be unpredictable, were significantly smaller and had lower total energy requirements than those from areas experiencing higher annual rainfall. These results indicate that S. campestris displays considerable geographical variation in energy requirements together with differences in the use of photoperiod as an anticipatory cue for predicting the onset of winter. These differences appear to be related to the availability of energy and the relative severity of climatic conditions in each locality.
Africa↗
Seasonal energy requirements and thermoregulation of growing pouched mice, Saccostomus campestris (Cricetidae).
Pouched mice (Saccostomus campestris) were born in captivity during January and March and subsequently maintained under long photoperiod (14 h light: 10 h dark) at 25 degrees C. During their first winter (July) and the following summer (January) the pouched mice were exposed to natural photoperiod in an unheated laboratory for 3 weeks prior to measurement. The pouched mice continued to grow during the study, and were significantly heavier after summer exposure than after winter exposure 6 months earlier. Although this increase in body mass would result in a decline in their surface area to volume ratio there was no significant decline in minimal thermal conductance (Cm) and winter-exposed pouched mice had a relatively lower Cm than expected. Meanwhile the smaller, winter-exposed animals displayed a significantly higher capacity for non-shivering thermogenesis, together with higher levels of basal metabolism than summer individuals. These differences were not solely attributable to the contrasting body mass of each group and it is therefore clear that S. campestris can increase thermoregulatory heat production, and modify heat loss following exposure to short photoperiod and cold during their first winter. Despite the significant increase in metabolism, the overall energy requirements of small, winter-exposed animals were significantly lower than those for heavier pouched mice following exposure to summer conditions. These results suggest that growing pouched mice can effectively adapt to lower temperature conditions during their first winter, yet accrue considerable overall savings in total energy requirements as a result of their smaller body mass.
Animals↗
Noradrenaline thermogenesis in conscious and anaesthetised pouched mice (Saccostomus campestris).
1. The metabolic response to injections of noradrenaline (NA) and saline (control) was investigated in conscious and anaesthetised (sodium pentobarbitone) pouched mice, Saccostomus campestris. 2. NA injection produced a calorigenic response which was significantly greater than that elicited by saline injection in both conscious and anaesthetised animals. 3. This calorigenic response was enhanced by motor activity in conscious pouched mice, but the exclusion of measurements recorded during visible activity eliminated the influence of movement. 4. Anaesthetised pouched mice underwent mild Hypothermia and displayed a retarded metabolic response to NA injection which suggests that anaesthesia affects the expression of NA-induced thermogenesis. 5. The validity of proposed techniques for the measurement of NA thermogenesis is further discussed.
Anesthesia↗
Ringtail in the pouched mouse (Saccostomus campestris).
Laboratory colonies of the pouched mouse (Saccostomus campestris) were housed in solid bottom cages and fed a varied diet containing excess fatty acids. Ringtail was only initiated in animals of all ages, from populations originating from different areas of South Africa, when the relative humidity fell below 30%. The incidence of ringtail was curtailed by maintaining relative humidity above 45% in animal houses.
Animals↗
Thermoregulatory circadian rhythms in the pouched mouse (Saccostomus campestris).
1. Circadian rhythms of body temperature (Tb), oxygen consumption (VO2), and minimal thermal conductance (C) were studied in the pouched mouse, Saccostomus campestris under natural photoperiod during February at a constant ambient temperature of 28 degrees C. 2. Circadian rhythms of body temperature were also studied under natural photoperiod and laboratory temperatures (Max: 28.1 degrees C; Min: 23.2 degrees C) during February. 3. The results of the present study suggest that changes in ambient temperature are not the main "zeitgeber" for body temperature rhythm, and it seems that photoperiod plays a major role in this species. 4. The relationship between the rhythms of Tb, VO2, and C are further discussed.
Animals↗
Malignant recurrent pheochromocytoma during pregnancy: case report and review of the literature.
Pheochromocytoma is an uncommon disorder associated with significant morbidity and mortality. When the disorder is discovered during pregnancy the risks are much greater. Malignant lesions represent only 10% of these tumors. Malignancy associated with pregnancy is even more rare. We present the fourth case of malignant pheochromocytoma and pregnancy to be reported in the literature. Surgery remains the mainstay of therapy. If the disorder is diagnosed early in pregnancy, surgical exploration should be considered after rapid medical control. If diagnosis is made later in pregnancy, medical control for the duration of the pregnancy should be attempted. Labor and vaginal delivery should be avoided because of an associated high morbidity and mortality. Cesarean section is recommended, once fetal maturity has been reached. Localization and definitive resection may be performed after delivery if exploration was not performed at the time of cesarean section. Although the prognosis of patients with malignant pheochromocytomas remains poor, there is hope of improving this prognosis in the future with use of new radiopharmaceutical agents and, possibly, new chemotherapy. Currently, aggressive surgical management not only appears to offer excellent palliation but likely prolongs survival of patients with malignant pheochromocytomas in selected cases.
Adrenal Gland Neoplasms↗
Practical approaches for estimating prepregnant body weight.
Measurements of prepregnant body weight have important research and clinical applications. In practice, however, they are not always recorded; even when they are, this information is not always readily available. For this reason, researchers and clinicians have to rely on retrospective estimates of prepregnant weight, which can be estimated using: 1) maternal self-reports, 2) retrospective extrapolation, or 3) standardized estimates that correct for weight gained during early pregnancy. The aim of the present study was to examine the relative merits of these three approaches. Maternal self-reports tend to be unreliable and biased, being influenced by a variety of sociodemographic characteristics that generally underestimate true prepregnant body weight. Estimates of prepregnant weight based on retrospective extrapolation are vulnerable to measurement error, transient fluctuations in body weight, and incorrectly assume that the rate of weight gain is constant throughout pregnancy. Standardized estimates that correct for weight gained during early pregnancy incorrectly presume that there is little interindividual variation in gestational weight gain and that weight gain is similar for each woman in consecutive pregnancies. Because none of these techniques can provide a precise measure of prepregnant weight, researchers have little alternative but to recruit and weigh women before they become pregnant, although measurements of body weight recorded during the first trimester of pregnancy may provide a reasonable indication of prepregnant weight. For clinicians, self-reports of prepregnant weight or measurements recorded early in pregnancy are probably sufficiently accurate for practical purposes whenever recent, accurate measurements of prepregnant weight are unavailable.
Anthropometry↗
Is there an independent association between parity and maternal weight gain?
The independent associations between parity and maternal body mass index (BMI), and between parity and maternal weight gain, were investigated using a combination of cross-sectional and longitudinal analyses based on a retrospective, repeat-pregnancy study that examined the change in maternal body weight from the beginning of one pregnancy to the beginning of the next. A group of 523 multiparous women who had been weighed regularly during pregnancy, and none of whom had fallen pregnant less than 12 months after the birth of their previous child, were examined. Sociodemographic, behavioural, medical, obstetric and perinatal data, together with antenatal measurements of maternal body weight and height, were abstracted from each mother's obstetric notes. Parity was found to be independently associated with maternal BMI (p < 0.001), gestational weight gain (p < 0.001) and interpregnancy weight gain (p = 0.032). Women of different parities were found to be at differential risk of long-term weight gain for two reasons. First, primiparous women are at risk of long-term weight gain because they gain the most weight during pregnancy, and high gestational weight gain is in itself a risk factor for long-term weight gain. Second, women of higher parity (4+) are at risk of long-term weight gain because they gain more weight in association with pregnancy, irrespective of the amount of weight they gain during their pregnancies. For women of parity 3 or less, the association between maternal body weight and parity appears to be the result of cumulative weight gained during successive pregnancies. For women of greater parity, the association between maternal body weight and parity is partly the result of cumulative excess gestational weight gained during successive pregnancies, and partly the result of gaining more weight from the beginning of one pregnancy to the next at later pregnancies.
Adult↗
Caesarean section rates in South Africa: evidence of bias among different 'population groups'.
OBJECTIVE: The aim of this study was to assess the effect of 'population group' classification, as a specific instance of 'racial' categorization, on caesarean section rates in South Africa. DESIGN: Information on 'population group' classification ('Black, 'Coloured', 'Indian', or 'White', as defined under apartheid legislation) and place of delivery, together with basic obstetric, sociodemographic and perinatal data, were extracted from the birth notification forms of 5456 children who made up the birth cohort of the Birth to Ten longitudinal study. This cohort included all births that occurred to mothers resident in Soweto-Johannesburg during a 7-week period in 1990. RESULTS: After accounting for differences in maternal age, gravidity, birth weight and gestational age at delivery, the rate of caesarean sections at private facilities was more than twice that at public facilities. Although there were significant differences in the utilisation of private facilities by women from different 'population groups', there was an independent effect of 'population group' classification on caesarean section rates: caesarean section rates among women classified as 'White' and 'Coloured' were significantly higher (95% confidence intervals for odds ratios: 1.40-2.42 and 1.05-1.81, respectively) than among women classified as 'Black'. CONCLUSION: 'Population group' differences in caesarean section rates among South African women are not explained by differences in demographic risk factors for assisted delivery, nor by differences in access to private health care. Instead, the differences in section rates may reflect the effect of bias in clinical decision-making, and/or differences among women from different 'population groups' in their attitude towards assisted delivery, and their capacity to negotiate with clinicians.
Adult↗