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Biomedical subjects

A McCallum

Publications and source records attributed to A McCallum.

17 recordsLinked to original sources
PubMed2000

Differentiation of the epithelial apical junctional complex during mouse preimplantation development: a role for rab13 in the early maturation of the tight junction.

We have investigated the mechanisms by which the epithelial apicolateral junctional complex (AJC) is generated during trophectoderm differentiation in the mouse blastocyst using molecular, structural and functional analyses. The mature AJC comprises an apical tight junction (TJ), responsible for intercellular sealing and blastocoel formation, and subjacent zonula adherens E-cadherin/catenin adhesion complex which also extends along lateral membrane contact sites. Dual labelling confocal microscopy revealed that the AJC derived from a single 'intermediate' complex formed following embryo compaction at the 8-cell stage in which the TJ-associated peripheral membrane protein, ZO-1alpha- isoform, was co-localized with both alpha- and beta-catenin. However, following assembly of the TJ transmembrane protein, occludin, from the early 32-cell stage when blastocoel formation begins, ZO-1alpha- and other TJ proteins (ZO-1alpha+ isoform, occludin, cingulin) co-localized in an apical TJ which was separate from a subjacent E-cadherin/catenin zonula adherens complex. Thin-section electron microscopy confirmed that a single zonula adherens-like junctional complex present at the AJC site following compaction matured into a dual TJ and zonula adherens complex at the blastocyst stage. Embryo incubation in the tracer FITC-dextran 4 kDa showed that a functional TJ seal was established coincident with blastocoel formation. We also found that rab13, a small GTPase previously localized to the TJ, is expressed at all stages of preimplantation development and relocates from the cytoplasm to the site of AJC biogenesis from compaction onwards with rab13 and ZO-1alpha- co-localizing precisely. Our data indicate that the segregation of the two elements of the AJC occurs late in trophectoderm differentiation and likely has functional importance in blastocyst formation. Moreover, we propose a role for rab13 in the specification of the AJC site and the formation and segregation of the TJ.

Animals↗
PubMed1999

Prospective evaluation of the potential role of teleradiology in acute interhospital trauma referrals.

BACKGROUND: Teleradiology is one form of telemedicine that would allow the transmission of radiographs before the transfer of acutely traumatized patients between referring and receiving hospitals. The purpose of this study was to evaluate the potential impact of a prehospital teleradiology system on trauma patient management and transfer. METHODS: Forty-four injured adults referred to a trauma center were included. The history, physical examination, and radiographic findings reported by the referring physician to the receiving physician were documented. The plain radiographs of the chest, pelvis, and cervical spine taken at the referring hospital were obtained after patient transfer. For each case, two reviewers blinded to the case (surgeon [S] and emergency department physician [E]) and one reviewer not blinded to the case were individually presented with the referring physician's report and the radiographs. The reviewers were surveyed as to the implications of viewing the plain radiographs taken at the referring hospital before patient transfer. RESULTS: Overall, the blinded reviewers felt that viewing the radiographs before transfer would have influenced care in 40% and 38% of cases as judged by (S) and (E), respectively, with a crude agreement of 67.5% (kappa level, 0.32). The blinded reviewers (S and E) commonly noted the following four changes in management as a result of viewing the referred radiographs: requested further clinical history (S, 18%; E, 23%), suggested further pretransfer interventions (S, 38%; E, 30%), suggested further pretransfer diagnostic tests (S, 25%; E, 13%), and emphasized precautions during transfer (S, 28%; E, 30%). The nonblinded reviewer suggested potential influence in the management of at least 65% of the cases. CONCLUSION: This study suggests that viewing the radiographs of acutely injured trauma patients has the potential to influence many aspects of the management of interhospital transfer.

Humans↗
PubMed1998

An outbreak of Salmonella enteritidis phage type 5a infection in a residential home for elderly people.

The first outbreak of Salmonella enteritidis phage type (PT) 5a infection to be reported occurred after a party in a residential home for elderly people in May 1995. The party was attended attended by 96 residents, staff and guests. S. enteritidis PT5a was isolated from 14 of the 25 clinical cases identified after the party and S. enteritidis PT4 from another clinical case. Two elderly residents with S. enteritidis PT5a infection died. Infection with S. enteritidis PT5a was associated with consumption of prawn in mayonnaise vol-au-vents, sausage rolls, corned beef sandwiches, and sausages. The investigation of this outbreak illustrated the difficulty that elderly people may have in the completion of questionnaires. It also highlighted areas for intervention; such as reminders about basic hygiene precautions to prevent secondary spread and the importance of coordinated reinforcement in the workplace of formal food hygiene training for cooks. The Food Safety Regulations 1995 came into force soon after this outbreak: their implementation would probably have prevented it.

Adolescent↗
PubMed1995

Marital status, change in marital status, and mortality in middle-aged British men.

The effects of marital status and change in marital status on mortality among middle-aged British men were examined in a prospective cohort study, the British Regional Heart Study. This is a nationally representative cohort of men selected at random from general medical practices in 24 towns in England, Wales, and Scotland. It comprises 7,735 men aged 40-59 recruited in 1978-1980 and followed up for 11.5 years. Marital status and a wide range of biologic and lifestyle variables were measured at screening, and changes in marital status were assessed after 5 years. Single (never-married) men had an increased risk of cardiovascular disease mortality (relative risk (RR) = 1.5, 95% confidence interval (CI) 1.0-2.2) and noncancer, noncardiovascular mortality (RR = 1.8, 95% CI 1.1-3.3) after adjustment for potentially confounding variables: age, social class, smoking, recall of ischemic heart disease, recall of diabetes mellitus, use of antihypertensive drugs, body mass index, physical activity, alcohol intake, employment status, systolic blood pressure, blood cholesterol, and forced expiratory volume in 1 second. Divorced/separated men were not at increased risk of mortality, and widowed men were only at increased risk of other non-cardiovascular disease mortality (RR = 2.4, 95% CI 1.1-5.3). There was no effect of marital status on cancer mortality. Men who divorced during the follow-up period were at increased risk of both cardiovascular disease mortality (RR = 1.9, 95% CI 0.9-3.9) and other non-cardiovascular disease mortality (RR = 4.0, 95% CI 1.5-10.6), but men who became widowed during this time were not at increased risk. The excess mortality among single and recently divorced men was not explained by poor health or by exposure to a wide range of risk factors. It is unlikely that selection bias, chance, or artifact is responsible for the general relation between marital status and mortality. Variable and incomplete control for confounding by socioeconomic status and risk factors for common diseases may explain some of the inconsistencies observed between studies and between different categories of unmarried men (i.e., never-married, widowed, and divorced). It is possible that the social support offered by marriage exerts a protective effect for some men.

Adult↗
PubMed1995

Inadequacy of intravenous heparin therapy in the initial management of venous thromboembolism.

To determine the adequacy of initial anticoagulation by intravenous heparin for patients who have deep venous thrombosis (DVT), and the factors that influence delayed anticoagulation, independent, duplicate chart review of 63 consecutive patients who had venography-proven DVT was conducted. Adequate heparinization (AH) was defined as an activated partial thromboplastin time (PTT) of more than 1.5 times the normal laboratory control. The proportions of patients achieving AH within 24 hours and 48 hours of initial heparin bolus were 46% and 62%, respectively. Patients who weighed more were less likely to achieve AH (p < 0.05), while patients receiving care from the thromboembolism service were more likely to achieve AH (p < 0.05). Low initial infusion rate was strongly but not significantly predictive of inadequate anticoagulation (p = 0.06). The mean heparin bolus and initial infusion rates were significantly lower than those suggested in the literature (p < 0.01). The AH rates were comparable to historical controls but suboptimal compared with the rates of 66% at 24 hours and 81% at 48 hours reported in association with heparin nomogram use (p < 0.05). A heparin nomogram is likely to achieve consistently higher rates of adequate heparinization.

Aged↗
PubMed1992

Perceptions about blood donation, transfusion and the risk of HIV infection: implications for the blood transfusion service.

To assess perceptions of risk of AIDS/HIV infection from donation to, and receipt of, blood from the British Blood Transfusion Service, we undertook self completion surveys (n = 1874, response rate 74%) and an interview survey (n = 300, response rate 77%) of students in three higher/further education establishments in the North East of England. In the postal survey 20.9% perceived a risk of acquiring HIV/AIDS after blood donation, and 4.8% perceived the risk to be moderate or high. Explanations for the perceived risk were usually inaccurate. Most people (62.3%) perceived that blood transfusion had a risk of HIV infection, and 13.4% reported this risk to be moderate or high. The explanations for the risk were generally correct. The interview survey largely confirmed the results of the postal survey. The perceived risk of contracting HIV infection on blood donation is not an artefact of survey method; a substantial minority perceive a risk where there is none. Some people remain unaware of the risk of HIV infection after blood transfusion and among others the risk is perceived as higher than is realistic. Further research and educational initiatives to help safeguard the efficient gathering and use of blood are warranted.

Adolescent↗
PubMed1992

Social surveys in HIV/AIDS: telling or writing? A comparison of interview and postal methods.

We compare a probability sample postal questionnaire survey and a quota controlled interview survey, and review the literature on these subjects. In contrast to other studies, where quota samples were not representative because of biased selection of respondents by interviewers, our quota sample was representative. Response rates were similar in our postal and interview surveys (74 and 77%, respectively), although many previous similar postal surveys had poor response rates. As in other comparison studies, costs were higher in our interview survey, substantive responses and the quality of responses to closed-ended questions were similar, and responses to open-ended questions were better in the interview survey. 'Socially unacceptable' responses on sexual behaviour were less likely in interviews. Quota controlled surveys are appropriate in surveys on HIV/AIDS under certain circumstances, e.g. where the population parameters are well known, and where interviewers can gain access to the entire population. Postal questionnaires are better for obtaining information on sexual behaviour, if adequate steps are taken to improve response rates, and when in-depth answers are not needed. For most surveys in the HIV/AIDS field we recommend the postal method.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Sex and the risk of HIV infection: the role of alcohol.

To investigate sexual behaviour under the influence of alcohol and the relationship between drinking habits and unsafe sex we carried out a postal and interview survey of 2174 students in the North East of England. Drinking habits were classified as non, light, medium and heavy, and cross-tabulated against sexual and other risk taking behaviour. Response rates of 74% and 77% were obtained in the postal and interview surveys respectively. In the postal survey, heavier drinkers were more likely to have unsafe sex such as casual sex without a condom, and sex with someone know to have many partners. Respondents associated alcohol with sexual risk taking; because of drinking too much, in the last year, 19% had not taken contraceptive precautions during sex. The interview survey largely confirmed postal survey results. There are three possible explanations of the association between drinking habits and unsafe sex: alcohol might disinhibit safer sex; young risk-takers may also drink more; or, drinking might be associated with unsafe sex by coincidence because sexual encounters often begin in licensed premises. Drinking habits should therefore be a priority issue for future HIV/AIDS related research, policy debate, and health education endeavour.

Adult↗
PubMed1988

Colonic diverticulosis in patients with colorectal cancer and in controls.

The barium enemas of 119 patients with colorectal cancer and 119 age-matched controls were examined for evidence of diverticula. Amongst men, 39.6% of patients with colorectal cancer had diverticulosis, compared with 50% in the control group. In the women, 39.3% of patients with colorectal cancer had diverticular disease, compared with 36% of the controls. There appears to be no significant aetiologic association between the two conditions, since they do not occur together more frequently than in controls, although each is reputedly the result of fibre lack.

Barium Sulfate↗
PubMed1986

Comparative study of endralazine and hydralazine for the treatment of hypertension uncontrolled by a beta-blocker and diuretic.

Endralazine and hydralazine were compared in a randomized double-blind, parallel group study lasting 1 year in 30 patients with essential hypertension inadequately controlled by a beta-blocker and a diuretic. Dosage ranged from 10 mg to 30 mg endralazine per day and from 75 mg to 200 mg hydralazine per day according to patient response. The results showed that endralazine was at least as effective as hydralazine in reducing blood pressure. Patients' tolerance, assessed by drop-out rate, was significantly better (p less than 0.05) in the endralazine group. No cases were found of drug-induced lupus-like syndrome on endralazine as opposed to 2 cases with hydralazine. The dose of endralazine required much less adjustment than that of hydralazine.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Guidelines for the use of imaging techniques for the investigation of venous thromboembolic disease.

The diagnosis of venous thromboembolic disease remains a difficult challenge. Chest radiography, ventilation/perfusion lung scanning, noninvasive leg testing, and pulmonary angiography were evaluated with regard to sensitivity, specificity, positive and negative predictive values. The need for treatment, observation, or serial testing with respect to risks and benefits of treatment and likelihood of serious outcomes was evaluated. The evidence for conclusions was based on the methodology and values of the Canadian Task Force on the Periodic Health Examination. The Diagnostic Imaging Advisory Group of the Canadian Association of Emergency Physicians developed eight recommendations.

Diagnostic Imaging↗
PubMedDate not supplied

The performance of three measures of health status in an outpatient diabetes population.

Both the late complications of diabetes and the means used to prevent them have a significant impact on the lives of people with the condition. Measuring quality of life is therefore important in assessing clinical need and evaluating the success of management. Three approaches to measuring health status were therefore compared in 284 randomly selected out-patients attending a hospital diabetes service. The measures used were the Nottingham Health Profile (NHP), four categories of an anglicized version of the Sickness Impact Profile (the Functional Limitations Profile (FLP)), and a scale of Positive Well-being (PWB). The results were found to be independent of questionnaire order and place of completion. The distributions of scores on the NHP and FLP scales were highly skewed, with a majority of cases scoring zero. NHP and FLP scores were related (p < 0.001) to age, but not otherwise to type of diabetes. Patients with angina, circulatory problems, and neuropathy scored significantly higher (up to p < 0.001) on several dimensions/categories of the NHP and FLP, but not the PWB scale. Severe visual impairment (worse than 6/36) was only related (p < 0.005) to NHP 'Mobility' and FLP 'Ambulation' and 'Home management'. Validation of scores by interview gave satisfactory results on all dimensions of the NHP except 'Energy', and all FLP categories except 'Recreations and pastimes'. No statistically significant association was observed between the PWB and the interviewer's assessments, but it did correlate (up to tau = 0.45, p < 0.001) with some social and psychological dimensions/categories of the NHP/FLP. In conclusion the PWB scale is independent of physical disability.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗