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Biomedical subjects

A Rogers

Publications and source records attributed to A Rogers.

At least 55 records · Page 3Linked to original sources
PubMed2001

Binding to and hemolysis of human erythrocytes by pyrularia thionin and Naja naja kaouthia cardiotoxin: inhibition by prothrombin.

Pyrularia thionin and snake venom cardiotoxin are strongly basic proteins which bind to and induce hemolysis of erythrocytes, cause depolarization of muscle cells, and influence the order and properties of phospholipids in cellular membranes. Earlier studies showed a competition between the thionin and cardiotoxin for a common binding site on erythrocytes, and the present study extends these studies to show a similar competition between prothrombin and both basic proteins. The competition between the thionin and prothrombin for binding sites on erythrocytes was shown by direct binding experiments using radiolabeled thionin. Whereas binding of thionin or cardiotoxin induces hemolysis as a consequence of membrane perturbation, prothrombin does not induce hemolysis. Although it binds to the same site, there is no penetration into and perturbation of the membrane. The competition between prothrombin and pyrularia thionin is not influenced by added Ca++. This indicates that membrane PS interacts in a specific and Ca++-independent manner with at least one site on prothrombin, as proposed earlier (Tendian and Lentz, 1990). The competition between thionin and prothrombin was also demonstrated for the release of radiolabeled chromate from loaded P388 cells. The competition observed with the P388 cells shows that the competition is not a unique phenomenon with erythrocytes, but occurs with other cell membranes.

Animals↗
PubMed2001

Diabetic amyotrophy masquerading as quadriceps tendon rupture: a word of caution.

Diabetic amyotrophy is predominantly a motor condition that involves various elements of the lumbosacral plexus but particularly that related to the femoral nerve. (1,3) It can present acutely as unilateral thigh pain followed by the development of weakness and later wasting in the femoral muscles, usually first seen in the quadriceps. We report on two cases of diabetic amyotrophy from different hospitals that presented with clinical signs and symptoms of quadriceps rupture. These patients underwent surgical exploration but in both the quadriceps tendons were found to be intact. Post-operative neurological consultations established the diagnosis as diabetic amyotrophy, which was confirmed with electrodiagnostic studies. We conclude that any quadriceps rupture in diabetics should be viewed with caution. Electrodiagnostic studies and imaging with ultrasound and magnetic resonance imaging should be carried out before exploratory surgery.

Aged↗
PubMed2001

The effect of shiftwork on driving to and from work.

A questionnaire study was conducted to obtain information from shiftworkers on the levels of tiredness experienced on the drive to and from work at different times of the day. The results demonstrated that, compared to non-shiftworkers, shiftworkers were more tired on the drive between their home and the workplace and more at risk of falling asleep behind the wheel. The main factors contributing to this increased level of sleepiness and associated driving impairment were the length of the sleep period prior to work, the type of shift and the travelling time. There was some evidence to suggest that on working days shiftworkers were more likely to be involved in an accident than non-shiftworkers. However, there were insufficient data to determine whether accidents were correlated with driver sleepiness.

Accidents, Traffic↗
PubMed2000

Evolving populations with overlapping generations.

In this paper, we extend a previously published model of an evolving finite population of multi-locus organisms, where the dynamics of the evolving system are described by the cumulants of the population efficacy distribution. We consider the case of overlapping generations and compare it to the previously studied case where generations are discrete. In the weak selection limit, we can solve the dynamics analytically and show that the changes in population genetic variance due to stochastic effects-genetic drift-is twice as great when generations overlap. The comparison of the dynamics of the two models shows many of the features seen in the comparison, performed by Moran, of simple one-locus genetic models with overlapping and non-overlapping generations. Studying the dynamics of the two models gives some insights into these comparisons.

Animals↗
PubMed2000

Intracerebral aneurysms in human immunodeficiency virus infection: case report and literature review.

We describe a child with human immunodeficiency virus infection who presented with a large subarachnoid hemorrhage. She had multiple saccular and fusiform aneurysms in the proximal cerebral arterial circulation and no evidence of bacterial or fungal infection. The arteriopathy coincided with a high human immunodeficiency virus RNA load. Human immunodeficiency virus may cause cerebral arteriopathy with potentially life-threatening complications.

AIDS Dementia Complex↗
PubMed2000

'All the services were excellent. It is when the human element comes in that things go wrong': dissatisfaction with hospital care in the last year of life.

Patient satisfaction surveys are seen as an important way of obtaining 'user views' of health service provision. However, there is a growing body of research and theoretical literature that questions the validity of the concept of 'patient satisfaction' and hence the use of this type of survey. A postbereavement survey of people who registered a random sample of cancer deaths in an inner London health authority was undertaken in 1996/7. The survey questionnaire (VOICES) included 14 open-ended questions which asked respondents to add any comments they felt were relevant about the care of the deceased. This paper uses these data to examine the causes of dissatisfaction with hospital-based care. Of the 229 informants responding to the questionnaire, 138 included some written comment about care in hospital. At least one negative comment was made by 59% (82) of those making any comment. Of these, 55% (44) rated the care given by doctors as 'excellent' or 'good' and 63% (50) rated that given by nurses as 'excellent' or 'good'. Qualitative analysis of responses to open questions suggest that expressions of dissatisfaction arise from a sense of being 'devalued', 'dehumanized' or 'disempowered' and from situations in which the 'rules' governing the expected health professional-patient relationships were broken. As such, the causes of dissatisfaction for this particular group of patients are similar to the causes of dissatisfaction with health care in general reported elsewhere. The palliative care approach emphasizes patient- and family-centred care and aims to promote physical and psychosocial well-being. The study findings suggest that adoption of the palliative care approach could reduce the experience of dissatisfaction for many service users, not only those whose deaths are anticipated.

Dehumanization↗
PubMed2000

Genetic perspectives on human origins and differentiation.

This is a review of genetic evidence about the ancient demography of the ancestors of our species and about the genesis of worldwide human diversity. The issue of whether or not a population size bottleneck occurred among our ancestors is under debate among geneticists as well as among anthropologists. The bottleneck, if it occurred, would confirm the Garden of Eden (GOE) model of the origin of modern humans. The competing model, multiregional evolution (MRE), posits that the number of human ancestors has been large, occupying much of the temperate Old World for the last two million years. While several classes of genetic marker seem to contain a strong signal of demographic recovery from a small number of ancestors, other nuclear loci show no such signal. The pattern at these loci is compatible with the existence of widespread balancing selection in humans. The study of human diversity at (putatively) neutral genetic marker loci has been hampered since the beginning by ascertainment bias since they were discovered in Europeans. The high levels of polymorphism at microsatellite loci means that they are free of this bias. Microsatellites exhibit a clear almost linear diversity gradient away from Africa, so that New World populations are approximately 15% less diverse than African populations. This pattern is not compatible with a model of a single large population expansion and colonization of most of the Earth by our ancestors but suggests, instead, gradual loss of diversity in successive colonization bottlenecks as our species grew and spread.

Animals↗
PubMed2000

Biochemical markers as predictors of rates of bone loss after menopause.

Biochemical markers of bone turnover may correlate with rates of bone loss in a group of postmenopausal women, but it is uncertain how useful they are in predicting rates of bone loss in the individual. The aim of this study was to determine the value of measurements of biochemical markers for the prediction of rates of bone loss in the individual. We studied 60 postmenopausal women (ages, 49-62 years), 43 of whom had gone through a natural menopause 1-20 years previously and 17 of whom had undergone hysterectomy 3-22 years ago. Lumbar spine bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DXA) over 2-4 years. Bone formation markers (bone-specific alkaline phosphatase [ibAP] and amino terminal of type I collagen [PINP] and osteocalcin [OC]) were measured in serum. Bone resorption markers (N-telopeptide of type 1 collagen [NTx] and immunoreactive free deoxypyridinoline [iFDpd]) were measured in urine and corrected for creatinine (Cr). Rates of bone loss were calculated as percent change per year. We found significant negative correlations (Spearman rank) between all measured biochemical markers and rate of change in bone density with r values ranging from -0.35 to -0.52. When markers and rates of bone loss were divided into tertiles, prediction of bone loss in an individual was poor (kappa < 0.2). There was an exponential relationship between rate of bone loss and years since menopause (YSM) in the 43 women having a natural menopause (r2 = 0.44; p = 0.008) indicating higher rates of loss in the early postmenopausal period. Levels of NTx, iFDpd, and PINP also showed a significant negative correlation with YSM. We conclude that there is a strong relationship between rates of spinal bone loss and levels of bone turnover markers. Although this is a small study, the results also suggest that using DXA measurements of the lumbar spine as the "gold standard," it is not possible to use biochemical markers to predict rate of bone loss in the individual.

Absorptiometry, Photon↗
PubMed2000

Immediate changes in biochemical markers of bone turnover and circulating interleukin-6 after parathyroidectomy for primary hyperparathyroidism.

OBJECTIVE: The time course of the immediate change in bone turnover after parathyroidectomy (PTX) for primary hyperparathyroidism (PHPT) is not clear. It is uncertain whether circulating interleukin-6 (IL-6) plays a role in mediating the acute withdrawal of the effects of parathyroid hormone (PTH) on bone turnover after PTX. The aims of this study were to determine the time course of immediate changes in biochemical markers of bone turnover after PTX and whether circulating IL-6 is involved in the immediate changes of bone turnover after PTX. DESIGN AND METHODS: IL-6 and bone turnover markers were measured in eight women (aged 55+/-11 years, mean+/-s.d. ) with PHTP at baseline and at 1-2h, and 1, 2, 5, 7 and 12 days after PTX. We compared the results with those from eight individually matched women (healthy controls) and five subjects undergoing major surgery (surgical controls). RESULTS: At baseline, serum levels of IL-6 and bone turnover markers were higher in PHPT than those in healthy controls (P<0.05). Serum levels of procollagen propeptides increased by 22 and 27% at days 2 and 5, respectively, compared with baseline (P<0.05). Serum tartrate-resistant acid phosphatase decreased by 2 days after PTX, and urinary collagen crosslinks decreased significantly by 21-41% within 24h (P<0.05). Serum IL-6 levels increased immediately in both PHPT and surgical controls at postoperative follow-up (repeated measures ANOVA). CONCLUSIONS: (1) PTX decreases bone resorption immediately and (2) circulating IL-6 is not involved in the changes in bone turnover immediately after PTX.

Adult↗