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Biomedical subjects

L Clarke

Publications and source records attributed to L Clarke.

At least 73 records · Page 4Linked to original sources
PubMed1999

Incomplete reporting of men's fertility in the United States and Britain: a research note.

We evaluate men's retrospective fertility histories from the British Household Panel Survey and the U.S. Panel Study of Income Dynamics (PSID). Further, we analyze the PSID men's panel-updated fertility histories for their possible superiority over retrospective collection. One third to one half of men's nonmarital births and births within previous marriages are missed in estimates from retrospective histories. Differential survey underrepresentation of previously married men compared with previously married women accounts for a substantial proportion of the deficits in previous-marriage fertility. More recent retrospective histories and panel-updated fertility histories improve reporting completeness, primarily by reducing the proportion of marital births from unions that are no longer intact at the survey date.

Bias↗
PubMed1999

Influence of thyrotrophin-releasing hormone on thermoregulatory adaptation after birth in near-term lambs delivered by caesarean section.

We investigated the hypothesis that exogenous stimulation with thyrotrophin-releasing hormone (TRH) immediately prior to umbilical cord clamping can improve thermoregulatory adaptation after birth in near-term lambs delivered by Caesarean section. Lambs received an umbilical vein injection of saline +/- TRH (8 microg) prior to cord clamping. The rate of change in colonic temperature and oxygen consumption after birth were not influenced by TRH, but TRH-treated lambs exhibited a greater incidence of shivering compared with controls over the first hour of neonatal life. Two and a half hours after birth, TRH-treated lambs possessed brown adipose tissue (BAT) with a higher thermogenic activity (i.e. GDP binding to mitochondrial protein), but their BAT had a reduced DNA content and they had less hepatic glycogen than control lambs. TRH administration had no effect on iodothyronine 5' deiodinase activity in BAT and liver, or on plasma concentrations of total triiodothyronine, thyroxine, cortisol or free fatty acids. Three TRH-treated but no control lambs, failed to establish continuous breathing, so tissues from these treated lambs together with time-matched controls were sampled 25 min after birth. These 'non-surviving' TRH-treated lambs had very high plasma catecholamine concentrations, but their lung weights were similar to controls. 'Surviving' TRH-treated lambs possessed lungs with less DNA than non-surviving TRH-treated lambs. It is concluded that umbilical vein injection of TRH prior to umbilical cord clamping increases the recruitment of both shivering and non-shivering thermogenesis after birth.

Adaptation, Physiological↗
PubMed1998

Centromeres: proteins, protein complexes, and repeated domains at centromeres of simple eukaryotes.

Similarities exist among components of simple and complex centromeres that may not have been expected on the basis of wide variation in size and sequence organization of centromeric DNAs among eukaryotes. Support is growing in systems from fungi to Drosophila for a model of centromere assembly and activation that is dependent on a particular underlying chromatin structure but not necessarily on a specific DNA sequence.

Animals↗
PubMed1998

Schizophrenia: all in the mind or locked in the brain?

This paper questions whether a natural science language can be transposed either into the care of individuals affected by mental illness or the educational curricula of those preparing to care for them. The importance of biological research into schizophrenia is not denied. However, it is suggested that paradigms which depend upon ownership (of knowledge) may be less worthwhile to schizophrenic people than an approach which rests upon a philosophy of being. In this sense, a consideration of the place of consciousness in investigations into brain function is stated to be relevant: issues of mind and brain are central to discussions about schizophrenia. It is not denied that the laboratory-bench may ultimately unravel genetic susceptibility to schizophrenia. However, a biology of persons - however persuasive its language - can lead, in the case of schizophrenia, to formulations of human defect. Forms of care which proceed from determinism can lead, as they did in the past, to the curtailment of individual aspirations for both carers and patients.

Biological Psychiatry↗
PubMed1998

Mental illness and Irish people: stereotypes, determinants and changing perspectives.

The causes of psychological illness in Irish people have been identified with colonial rule and the catastrophic conditions deriving from famine in the nineteenth century. In particular, the scourge of unremitting emigration, resulting from famine, has formed a background against which speculative theories of inferiority, alienation and mental illness have been constructed. In particular, the long standing idea that Irish people exhibit higher rates of schizophrenia, both in Ireland and abroad, is discussed. Contemporary studies which suggest that these elevated rates do not correspond to international diagnostic criteria for schizophrenia are introduced. Rather, these enhanced rates may reflect a malaise which resembles schizophrenia but which is really a product of historical dispossession. The importance of these factors is underscored by the previous neglect of Irish people, considered as an ethnic minority, as well as the particular distaste which many Irish people display towards such a notion.

Attitude to Health↗
PubMed1998

Influence of maternal bodyweight on adaptation after birth in near-term lambs delivered by Caesarean section.

The present study investigated the influence of maternal bodyweight on adaptation after birth in near-term lambs delivered by caesarean section. One twin lamb from a heavy (>60 kg) or light ewe (<55 kg) was randomly taken and immediately placed into a warm (30 degrees C) ambient temperature and its twin then delivered into a cool (15 degrees C) ambient temperature. Continuous recordings of colonic temperature were then made followed by measurements of thermoregulation and brown adipose tissue function up to 6 h of life. Following caesarean section delivery colonic temperature rapidly declined over the first 30 min of life, a response that was greater in lambs at 15 degrees C. Irrespective of ambient temperature all lambs born to heavy ewes commenced shivering within 15 min of birth and were able to restore body temperature. These adaptations were only observed in warm-delivered lambs born to light ewes, as cool-delivered lambs failed to shiver, became hypothermic and 4 out of 6 lambs exhibited respiratory failure. Umbilical vein plasma thyroid hormone concentrations were lower in lambs born to light compared with heavy ewes. Plasma T3 concentrations remained lower in warm-delivered lambs born to light ewes until 2 h after birth when heat production and colonic temperature were not significantly different from warm delivered lambs born to heavy ewes. Lambs born to light ewes possessed less brown adipose tissue than those born to heavy ewes. In conclusion, maternal bodyweight has a critical influence on survival following caesarean section birth that is dependent on the ambient temperature into which a lamb is delivered.

Adaptation, Physiological↗
PubMed1998

Maternal nutrition in early-mid gestation and placental size in sheep.

We investigated the influence of restricted maternal nutrition between 30 and 80 d gestation on placental growth. Singleton-bearing ewes were fed on either 0.6 (i.e. nutrient restricted) times their energy requirements of 2.25 times this amount (i.e. controls) up to 80 d gestation, when their placentas and fetuses were sampled and analysed. Nutrient-restricted ewes lost body condition score but not body weight and had lower plasma thyroid hormone concentrations than controls, but there were no differences in plasma glucose, non-esterified fatty acids or 3-hydroxybutyrate concentrations between groups. There was no effect of maternal nutrient restriction on fetal weight, conformation or organ weight with the exception of brain weight which was lower nutrient-restricted ewes. Nutrient restriction had no effect on total placental weight, or proportion of inverted placentomes, but was associated with an increased abundance of small placentomes and decreased weight of the fetal but not maternal components of the placenta. Fetal cotyledons form nutrient-restricted ewes also had a lower DNA but higher haemoglobin concentration than those sampled from controls. The plasma concentration of triiodothyronine in umbilical cord plasma was also increased in fetuses from nutrient-restricted ewes. In conclusion, maternal nutrient restriction during early-mid gestation is associated with a smaller placenta.

Animal Nutritional Physiological Phenomena↗
PubMed1998

Thermoregulation in newborn lambs: influence of feeding and ambient temperature on brown adipose tissue.

We have previously shown that feeding 50 ml of colostrum can increase the thermogenic activity of brown adipose tissue (BAT) in newborn lambs maintained at a warm (30 degrees C) ambient temperature. This study further examines the effect of ambient temperature on BAT and thermoregulation by investigating the response to feeding 50 ml of water. Immediately after vaginal birth, lambs were placed in either a warm (30 degrees C) or cool (15 degrees C) environment a ambient temperature and measurements of colonic temperature and heat production were recorded for 6 h. Lambs were fed 50 ml of water when 5 h old. The level of guanosine 5'-diphosphate (GDP) binding was higher, but adrenaline content lower in BAT sampled from lambs maintained at 15 degrees C compared with those at 30 degrees C. Feeding was associated with an increase in colonic temperature and plasma concentrations of glucose and non-esterified fatty acids in lambs maintained at 15 degrees C only. In this group plasma concentrations of adrenaline and dopamine declined after feeding, but noradrenaline concentrations were not influenced by feeding in either group of lambs. O2 consumption and CO2 production were higher in lambs maintained at 15 degrees C but were not influenced by ambient temperature or feeding. It is concluded that feeding a small volume of water can influence thermoregulation by a mechanism that is dependent on the ambient temperature at which the lamb is maintained.

Adipose Tissue, Brown↗
PubMed1998

Influence of thyrotrophin-releasing hormone on thermoregulation in newborn lambs.

This study examined the effect of thyrotrophin-releasing hormone (TRH) administration on thermoregulation in the newborn. Twin lambs were either delivered near-term by caesarean section or born vaginally at term. Colonic temperature, O2 consumption, CO2 production, breathing and heart rates, plus plasma thyroid hormone and nonesterified fatty acid (NEFA) concentrations and thermogenic activity (i.e. GDP binding) of brown adipose tissue (BAT) were measured. In caesarean section delivered lambs colonic temperature decreased rapidly after birth, a response that was greater in the group designated for TRH treatment, in which colonic temperature fell to below 36.0 degrees C at 80 min of life, prior to TRH administration. At this age colonic temperature had been restored to a mean of 38.70 degrees C in controls. TRH had no influence on the composition or thermogenic activity of BAT. The incidence of shivering was not influenced by TRH, but treated lambs maintained a higher rate of O2 consumption and ventilation compared with controls after colonic temperature had been restored to 38.56 degrees C. TRH appeared to promote fat oxidation as O2 consumption remained unchanged and CO2 production declined by a greater rate in treated lambs, resulting in a lower respiratory quotient compared to controls. Heart rate and plasma concentrations of NEFA increased following TRH administration although this did not result in values greater than controls. Normothermic lambs born vaginally had BAT with a greater thermogenic activity, higher plasma thyroid hormone and NEFA concentrations compared with caesarean section delivered lambs, but a thermogenic response was not observed to TRH despite a rise in thyroid hormone concentrations. In conclusion, TRH can improve thermoregulation, an effect that could be linked to an increase in fat oxidation.

Animals↗
PubMed1998

Influence of restricted maternal nutrition in early to mid gestation on placental and fetal development at term in sheep.

We investigated the influence of restricted maternal nutrition between 28 and 77 d of gestation on placental weight and appearance, and on fetal weight and conformation. Single-bearing ewes were fed either twice [i.e. controls (n = 19)] or half [i.e. nutrient-restricted (n = 28)] their energy requirements from 28 to 77 d of gestation, after which all ewes were fed to fully meet the energy requirements for maintenance and pregnancy. Close to term (145 +/- 1 d) placental weight was higher in the nutrient-restricted group [nutrient-restricted, 416.3 +/- 12.6 g; controls, 347.4 +/- 17.6 g (p < 0.01)], as was the abundance of everted placentomes. There was no significant difference in total fetal weight, or weights of individual organs between groups, but crown-rump length was significantly greater in lambs born to nutrient-restricted ewes [nutrient-restricted, 50.4 +/- 0.4 cm; controls, 48.2 +/- 0.6, cm (p < 0.01)]. Fetal to placental weight ratio was lower in the nutrient-restricted group [nutrient-restricted, 9.51 +/- 0.23; controls, 10.81 +/- 0.39 (p < 0.01)]. A stronger relationship between the total weight of the fetal component of the placental and fetal weight was observed in controls (r2 = 0.50) than in nutrient-restricted ewes (r2 = 0.18). In conclusion, maternal nutrient restriction over the period of rapid placental growth results in a larger placenta and altered placental to fetal weight ratio if ewes are subsequently fed to requirements for the remainder of gestation.

Analysis of Variance↗
PubMed1998

Self-mutilation: culture, contexts and nursing responses.

Few papers address the issue of deliberate self-mutilation other than from clinical perspectives. This paper advocates a user-perspective and discusses some of the issues which might attend such a change. The occurrence of self-mutilation is placed within a cultural framework so as to enlarge the debate beyond the confines of medical/nursing responses. It is suggested that nurses abrogate their attachment to such responses and embrace more collaborative approaches to care. In particular, nurses are asked to review their (moral) responses to self-mutilation, an activity which, too often, has been responded to with scorn and derision.

Adolescent↗
PubMed1998

Fathers and absent fathers: sociodemographic similarities in Britain and the United States.

Using data from the British Household Panel Survey and the National Survey of Families and Households in the United States, we present a sociodemographic profile of fathers and compare the determinants of absent fatherhood in each country. Although fatherhood has a younger profile in the United States, especially for blacks, predictors of fathers' residency with their children are remarkably similar in the two countries. In both countries, the strongest predictor of a father's absence is the parent's relationship to each other at the time of the child's birth. Policy implications of this finding are discussed.

Adolescent↗
PubMed1998

Mental illness and Irish people: stereotypes, determinants and changing perspectives.

The causes of psychological illness in Irish people have been identified with colonial rule and the catastrophic conditions deriving from famine in the nineteenth century. In particular, the scourge of unremitting emigration, resulting from famine, has formed a background against which speculative theories of inferiority, alienation and mental illness have been constructed. In particular, the long standing idea that Irish people exhibit higher rates of schizophrenia, both in Ireland and abroad, is discussed. Contemporary studies which suggest that these elevated rates do not correspond to international diagnostic criteria for schizophrenia are introduced. Rather, these enhanced rates may reflect a malaise which resembles schizophrenia but which is really a product of historical dispossession. The importance of these factors is underscored by the previous neglect of Irish people, considered as an ethnic minority, as well as the particular distaste which many Irish people display towards such a notion.

Attitude to Health↗
PubMed1997

A centromere DNA-binding protein from fission yeast affects chromosome segregation and has homology to human CENP-B.

Genetic and biochemical strategies have been used to identify Schizosaccharomyces pombe proteins with roles in centromere function. One protein, identified by both approaches, shows significant homology to the human centromere DNA-binding protein, CENP-B, and is identical to Abp1p (autonomously replicating sequence-binding protein 1) (Murakami, Y., J.A. Huberman, and J. Hurwitz. 1996. Proc. Natl. Acad. Sci. USA. 93:502-507). Abp1p binds in vitro specifically to at least three sites in centromeric central core DNA of S. pombe chromosome II (cc2). Overexpression of abp1 affects mitotic chromosome stability in S. pombe. Although inactivation of the abp1 gene is not lethal, the abp1 null strain displays marked mitotic chromosome instability and a pronounced meiotic defect. The identification of a CENP-B-related centromere DNA-binding protein in S. pombe strongly supports the hypothesis that fission yeast centromeres are structurally and functionally related to the centromeres of higher eukaryotes.

Amino Acid Sequence↗
PubMed1997

Treatment of ulcerative colitis with an engineered human anti-TNFalpha antibody CDP571.

BACKGROUND: Tumour Necrosis Factor-alpha (TNFalpha) is a pro-inflammatory cytokine whose expression is increased in the colonic mucosa of patients with active ulcerative colitis. TNFalpha antibodies have been shown to be beneficial in animal models of bowel inflammation and in Crohn's disease but have not previously been studied in ulcerative colitis. METHODS: Patients with mild/moderate ulcerative colitis were treated openly with a single intravenous infusion of 5 mg/kg of an engineered human IgGgamma4 antibody CDP571 and monitored for 8 weeks. RESULTS: Fifteen patients entered the study, eight males and seven females, with a mean age of 44 years. Eleven had left-sided disease, four extensive disease and six patients were steroid-unresponsive. The treatment was well tolerated and plasma half-life of CDP571 was approximately 7 days. There was a significant reduction from 6.7 to 4.6 (P = 0.023) in the mean Powell-Tuck score by 1 week post-infusion and a reduction to 5.5 was seen at 2 weeks (P = 0.218). Significant but modest reductions also occurred in erythrocyte sedimentation rate and serum C reactive protein in the first 2 weeks. Mean Interleukin-6 plasma concentrations fell from 6.9 to 5.4 pg/mL by week 1, and to 6.1 pg/mL by week 2 (NS). Reductions in sigmoidoscopic score and number of liquid stools were noted but failed to reach statistical significance. CONCLUSION: A consistent improvement in disease activity was seen in the initial 2 weeks after infusion and the treatment was well tolerated. These promising results support the testing of CDP571 in a larger controlled trial.

Adult↗