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Biomedical subjects

A Collins

Publications and source records attributed to A Collins.

At least 253 records · Page 14Linked to original sources
PubMed1966

Coordinate synthesis of heme and apoenzyme in the formation of tryptophan pyrrolase.

Reciprocal control mechanisms between hemoprotein and 8-aminolevulinic acid synthetase take part in coordinate synthesis of the heme and apoenzyme moieties of tryptophan pyrrolase. Stimulation of heme biosynthesis increases tryptophan pyrrolase, whereas enhancement of heme binding by apotryptophan pyrrolase secondarily increases the formation of delta-aminolevulinic acid synthetase, the rate-limiting enzyme in heme formation. Tryptophan-mediated induction of delta-aminolevulinic acid synthetase suggests that heme participates in repression of that enzyme

Amino Acids↗
PubMedDate not supplied

Vitamin D intake and status in Irish elderly women and adolescent girls.

AIM: To assess vitamin D status during summer and winter in Irish girls and elderly women, and to estimate vitamin D intake in these two age-groups. METHODS: Ambulatory free-living, elderly Irish women (aged 70-76 years; n = 43) and girls (aged 11-13 years; n = 17) were recruited. Fasting serums were collected during August/ September 2002 and February/March 2003 and analysed for 25 (OH) D by HPLC. RESULTS: Mean daily intakes of vitamin D were 4.6 microg and 2.1 microg in elderly women and girls, respectively. Serum 25 (OH) D was significantly lower (P<0.001) during winter than summer in both age-groups. Eight (20%) and one (during late summer) and sixteen (37.2%) and eight (47%) (during late winter) of the elderly women and girls, respectively, had inadequate vitamin D status (serum 25 (OH) D <40 nmol/l). CONCLUSION: Inadequate vitamin D status during winter time is quite common in elderly women and adolescent girls in Ireland.

Adolescent↗
PubMedDate not supplied

Effects of taipan (Oxyuranus scutellatus) venom on erythrocyte morphology and blood viscosity in a human victim in vivo and in vitro.

The case of a snake handler with envenoming due to Australian taipan (Oxyuranus scutellatus) showing marked morphological changes in his red blood cells is presented. The red cells underwent sphero-echinocytic transformation and in subsequent experiments in vitro the effects of taipan venom on red cells were further characterized. Taipan venom induced sphero-echinocytic transformation at nanogram/ml concentrations and led to a marked increase in whole blood viscosity. These changes have not been featured in previous reports of taipan envenomation and are reported to highlight the diagnostic value of blood film examination in cases of suspected envenomation. The significance of the hyperviscosity, and consequent reduction in blood fluidity, is unknown and requires further investigation.

Adult↗
PubMedDate not supplied

Volunteer blood donors who fail the copper sulfate screening test. What does failure mean, and what should be done?

Volunteers attending blood donor sessions who fail the copper sulfate screening test merit an explanation of why they are considered ineligible to donate. During a 30-month period, 0.24 percent of men and 2.8 percent of women attending blood donor sessions in the northern region of England failed this test. Their hematologic status was determined by performing complete blood counts on a venous blood specimen and measuring ferritin as an indication of iron stores in a representative sample of approximately 10 percent. Normal blood counts were found in some donors, while others had severe degrees of anemia, and such discrepancies could be clarified only by hemoglobin determinations. Iron deficiency was very common in deferred donors, including 36 of the 88 with normal blood counts in whom ferritin assays were performed. Microcytic blood cells, a hallmark of iron deficiency, were found to be a relatively insensitive measure of low iron stores, except at low levels of hemoglobin. By a check of a venous sample, the hematologic status of most volunteers failing the copper sulfate screening test can be ascertained, and appropriate review, investigation, and treatment can be undertaken.

Blood Donors↗
PubMedDate not supplied

Post-translational processing of barley beta-glucan endohydrolases in the baculovirus-insect cell expression system.

Two cDNAs encoding barley (1-->3,1-->4)-beta-glucanase (EC 3.2.1.73) isoenzymes EI and EII have been expressed in Spodoptera frugiperda (Sf9) cell cultures using the baculovirus AcNPV vector. Modifications to both the 5' and 3' ends of the cDNAs were required before satisfactory levels of expression were obtained. The modified cDNAs directed high levels of (1-->3,1-->4)-beta-glucanase expression in the Sf9 insect cell cultures, with yields of approximately 10 mg/liter of isoenzyme EI (expEI) and 15 mg/liter of isoenzyme EII (expEII). Amino acid sequence analyses showed that the expressed enzymes were processed correctly at their amino termini. However, affinity chromatography of the isoenzyme expEII on concanavalin-A (conA)-Sepharose indicated that, although the enzyme is glycosylated, the structures of the carbohydrate chains differ from those of the native enzyme. When a cDNA encoding the homologous barley (1-->3)-beta-glucanase (EC 3.2.1.39) isoenzyme GII was expressed in insect cells, aberrant amino-terminal processing of the nascent polypeptide was sometimes observed. The forms with incompletely removed signal peptides retained their substrate specificity, but exhibited slightly reduced catalytic efficiency, altered chromatographic behavior, and reduced stability at elevated temperatures. The results show that high levels of expression of recombinant plant proteins can be obtained in insect cells, but they emphasize the need to characterize thoroughly the products that are expressed in the heterologous insect cell system before comparisons are made with the native enzyme or with engineered enzyme mutants.

Amino Acid Sequence↗
PubMedDate not supplied

A new approach to optimizing urea clearances in hemodialysis and continuous ambulatory peritoneal dialysis.

Recent studies suggest that the relationship of the net normalized protein catabolic rate (which is the normalized protein equivalent of nitrogen appearance [nPNA]) to the weekly clearance of urea normalized to total body water (Kt/V urea) in patients on continuous ambulatory peritoneal dialysis (CAPD) is curvilinear, rather than linear, as has been thought. The authors have reexamined the relationship of nPNA to weekly Kt/V urea in a CAPD population by cross-sectional analysis to see if the curvilinear definition of the relationship is as good as or better than the usual linear description. They also examined this relationship in the hemodialysis populations at the Dialysis Clinics Inc. in Columbia, Missouri, and in the Renal Kidney Disease Program in Minneapolis, Minnesota. It seems obvious that there should be a plateau of nPNA in each therapy because extension of linear regressions would predict protein intakes of normal individuals exceeding 8 g/kg/body weight/day. The authors compared their findings to other published results. Intuitively and analytically, the curvilinear relationships seem likely. The authors observed that the nPNA plateau is achieved at lower Kt/V in patients on CAPD than in those on hemodialysis, which is compatible with the peak concentration hypothesis. Asymptotes for CAPD and hemodialysis are similar. Weekly Kt/V urea requirements to achieve nPNA values at 95% of the asymptote are greater than those usually delivered. However, such nearly complete elimination of uremic appetite suppression may not be practical or necessary for achieving acceptable nutritional status and long-term survival in most patients. Optimum therapy may be well above adequate therapy relative to minimizing appetite suppression by uremia.

Appetite↗
PubMedDate not supplied

Psychoneuroendocrine stress responses and mood as related to the menstrual cycle.

Psychoneuroendocrine stress responses were studied in normally ovulating women in the follicular, ovulatory, and luteal phases of two consecutive menstrual cycles. Psychologic stress was induced by having the subjects perform a battery of cognitive tasks under time pressure. Blood samples were drawn after each session for radioimmunoassay of 17 beta-estradiol, progesterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, prolactin, cortisol, and androstenedione. Urine samples were obtained for estimation of adrenaline, noradrenaline, and cortisol. The results showed that psychoneuroendocrine stress responses as estimated by urinary excretion of adrenaline and noradrenaline varied significantly across the menstrual cycle, the highest values being obtained in the luteal phase. Self-reported mood and somatic symptoms showed distinct phase-related changes, with more negative mood states predominating in the luteal and menstrual phases and increased positive mood states in the follicular and ovulatory phases.

Adult↗
PubMedDate not supplied

Cardiovascular responses to psychological and physiological stressors during the menstrual cycle.

Psychological and physical stress reactivity was studied in 15 females in two phases of the menstrual cycle (cycle days 5-7 and 24-26) and in 15 males. Each female was matched for age and time between sessions with a male. There was a significant phase-related difference in cardiovascular reactivity among the females. Females in the luteal phase reacted significantly more to the cold pressor but not to the mental arithmetic test. There were significant sex differences in systolic blood pressure, the males displaying higher levels during provocation, as well as during control conditions. The females were more reactive in heart rate to the mental stressor when changes from control conditions to stress were calculated. When the data were analyzed separately for smokers and non-smokers, there was a significant interaction between menstrual cycle phase and smoking. In the luteal phase, the female smokers were more reactive in systolic blood pressure than the non-smokers. The male smokers were more reactive than the non-smokers in diastolic blood pressure response to mental arithmetic, but not to the cold pressor test. Significantly higher levels of cortisol and aldosterone were found in the luteal phase as compared with the follicular phase. The cortisol levels were higher in the males than in the females in the follicular phase, whereas the female aldosterone concentrations in the luteal phase were higher than those of the males.

Adult↗
PubMedDate not supplied

Menopausal transition and psychological development.

OBJECTIVE: To study women's psychological development during menopause and to examine the relationship between women's appraisal of menopause and symptom reporting. DESIGN: A population-based sample of 130 healthy women was assessed annually for 5 consecutive years using semistructured interviews, a menopausal symptom rating scale, and the Symptom Checklist-90 rating scale. RESULTS: Qualitative analyses of the interviews showed that the majority of the women (57%) had neutral beliefs about menopause, whereas 31% were pessimistic and 12% were optimistic. Optimistic and neutral expectations were associated with low levels of symptom reporting, whereas the pessimistic appraisal was significantly related to elevated symptom scores. The majority of the neutral and pessimistic women reappraised menopause during the study period, and at the last follow-up, 67% appraised menopause positively. A positive reappraisal among the initially pessimistic women was associated with more frequent statements about personal growth compared with the other subgroups. CONCLUSIONS: Menopause has a developmental potential and is a positive period for most women.

Adaptation, Psychological↗
PubMedDate not supplied

Limb girdle muscular dystrophy type 2A (CAPN3): mapping using allelic association.

Recently a graphical study of linkage disequilibrium around the CAPN3 locus failed to refine the 1.3-Mb interval suggested by haplotype sharing. On the contrary, the Malecot model as implemented in the ALLASS program maps CAPN3 within 3 kb of its true location (23 kb from the locus midpoint), overcoming identified problems with small samples, interrelated sibships, and short duration.

Alleles↗
PubMedDate not supplied

Mapping in the sequencing era.

The present phase of the Human Genome Project is concerned with sequencing. The shift of emphasis has left an impression that mapping is in some sense complete or finished. On the contrary, faced with the challenges of mapping genes for complex traits and efforts to understand recombination and other biological processes, the need for accurate integrated metric maps is greater than ever. Furthermore, sequencing could be regarded as merely a way of improving the map, since the most useful 'end product' of the sequencing effort must be the annotated sequence that gives precise physical coordinates for markers and expressed sequences. Integration of both location and functional information, the latter provided by homology, expression and other functional studies, is the main target for the future.

Chromosome Mapping↗
PubMedDate not supplied

Segregation analysis of colorectal cancer in Northern Ireland.

The genetic basis for colorectal cancer was investigated by complex segregation analysis of a published series of 305 pedigrees ascertained through a large population database. Two hundred and five of the pedigrees were ascertained through patients diagnosed with colorectal cancer before age 55, and 100 from patients diagnosed with colorectal cancer between the ages of 55 and 74. The analysis was carried out using the program POINTER. Using the joint-likelihood approach, the familial aggregation of colorectal cancer was compatible with the inheritance of a dominant gene. The gene frequency of the putative abnormal allele was 0.002 with a lifetime penetrance of 85%. However, under conditional likelihood, this mode of inheritance for a major gene was not favoured. The possible aetiologies of this paradoxical finding are discussed.

Adult↗