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Biomedical subjects

G Hart

Publications and source records attributed to G Hart.

At least 109 records · Page 6Linked to original sources
PubMed1994

Prospective evaluation of cerebral angiography and computed tomography in cerebral haematoma.

One hundred and two consecutive patients with cerebral haematoma were prospectively allocated to one of two groups according to their CT on admission. Group 1 patients were thought to have a high probability of an underlying structural lesion and underwent cerebral angiography acutely. If normal, this was repeated at three months. Group 2 patients were thought not to have such a lesion and underwent angiography at three months. Patients older than the mean age of the study population, and hypertensive patients were much less likely to harbour an aneurysm or arteriovenous malformation than younger or normotensive patients (p < 0.01; sensitivity 87.9%, specificity 88.6%). An aneurysm or arteriovenous malformation was the cause of haemorrhage in 12.8% of hypertensive patients, in 30.9% of patients with haematoma involving the basal ganglia, and 18.2% of those with posterior fossa haemorrhage. Features of CT in isolation give a sensitivity of 77.2% and a specificity of 84.2%. Follow up angiography in group 1 showed an arteriovenous malformation in one of seven patients in whom the original study was normal. These results contrast sharply with data from previous retrospective studies. The decision to investigate a patient with cerebral haematoma should be primarily based on the patient's clinical condition, rather than on the site of haemorrhage.

Adolescent↗
PubMed1994

Illiteracy among Medicaid recipients and its relationship to health care costs.

Poor literacy is associated with poor health status, but whether illiteracy is also linked to higher medical care costs is unclear. We characterized the literacy skills of 402 randomly selected adult Medicaid enrollees to determine if there was an association between literacy skills and health care costs. Each subject's literacy skills were measured with a bilingual (English/Spanish) reading-assessment instrument. We also reviewed each subject's health care costs over the same one-year period. The mean reading level of this Medicaid population was at grade 5.6. Mean annual health care costs were $4,574 per person. There was no significant relationship between literacy and health care costs. While there are compelling reasons to improve poor reading skills among Medicaid enrollees, illiteracy in this population does not appear to contribute to the high cost of providing government-sponsored care.

Adolescent↗
PubMed1994

Perceptions of general practice among homosexual men.

BACKGROUND: Primary care has an important role to play in the prevention and management of the human immunodeficiency virus (HIV). It has been suggested that homosexual men experience a variety of problems in relation to primary care. AIM: As part of a larger study, it was decided to examine the extent to which a sample of homosexually active men experienced difficulties in general practice and whether they consulted their general practitioner for problems related to HIV or the acquired immune deficiency syndrome (AIDS). METHOD: Homosexual men were recruited for interview in 1991-92 from a variety of sources including genitourinary clinics and homosexual organizations. RESULTS: Of 623 men registered with a general practitioner 44% had not informed their general practitioner of their sexual orientation and 44% of the 77 men who were HIV antibody positive, as confirmed by the study, had not informed their general practitioner of this fact. Men who viewed their practice as unsympathetic towards homosexual men were less likely to have informed their general practitioner of their sexual orientation or HIV status. The majority of men (87%) nevertheless viewed primary care as an appropriate source of HIV/AIDS advice. CONCLUSION: There is considerable scope for improvement in the acceptability of general practice to homosexual men.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Changes in cell length consequent on depolarization in single left ventricular myocytes from guinea-pigs with pressure-overload left ventricular hypertrophy.

Cell length was measured in single guinea-pig left ventricular myocytes by using a high-resolution photodiode array. Step depolarizations from a holding potential of -45 mV were applied using a switch-clamp technique with 2 M KCl microelectrodes, which were devoid of Ca2+ buffering. Comparison was made between myocytes from sham-operated guinea-pigs and guinea-pigs with mild pressure-overload left ventricular hypertrophy induced by infra-renal aortic constriction. The relation between cell shortening and membrane voltage was bell shaped, and a phasic component of shortening was evident at the range of potentials over which the L-type calcium current was activated. Mean cell shortening was increased in the hypertrophy group, and was maximal at +15 mV in both groups (control, 7.6 +/- 0.9 microns, n = 11, hypertrophy 11.0 +/- 1.2 microns, n = 20, p < 0.05). The latency to the onset of contraction was significantly shorter in the hypertrophy myocytes at -25 mV and at potentials positive to +50 mV. The relation between time-to-peak shortening and voltage showed a trend to shorter times in the hypertrophy group. At very positive potentials a slow component of contraction was identified which was relatively larger in the hypertrophy myocytes. This finding is consistent with increased calcium entry via sarcolemmal sodium-calcium exchange in the myocytes from the hypertrophy group.

Action Potentials↗
PubMed1993

Membrane current changes in left ventricular myocytes isolated from guinea pigs after abdominal aortic coarctation.

OBJECTIVE: The aim was to look for membrane current changes as a basis for the prolongation of action potential duration in left ventricular myocytes following abdominal aortic coarctation. METHODS: Immature female guinea pigs underwent laparotomy and an aortic coarctation was fashioned immediately distal to the renal arteries. After 20 weeks the hearts were removed and single myocytes were isolated from the left ventricles by standard enzymatic techniques. The switch-clamp technique was used. RESULTS: Heart weight:body weight ratio was increased by 7% in the coarctation group (p < 0.01). Systolic left ventricular pressure was 59(SEM 4) mm Hg in control and 76(7) mm Hg in coarctation animals (p < 0.05). Cell capacity was increased by 21% in the coarctation group (p < 0.05), and mean resting potential was 4.6 mV more negative in this group (p < 0.001). Action potential duration at 90% repolarisation was 310(17) ms in the control group (n = 22) and 358(13) ms in the coarctation group (n = 34, p < 0.05). Peak density of L-type calcium current was -8.6(0.4) pA.pF-1 in control and -11.1(0.7) pA.pF-1 in coarctation cells (p < 0.01). The regression line for calcium current versus cell capacity was shifted to higher calcium currents in the coarctation group. The half inactivation potential for this current was shifted by 11.5 mV (p < 0.01). Calcium-activated tail currents were larger and the envelope of tail currents was prolonged in the coarctation cells. No significant differences were found in the amplitude of IK or of IKl. CONCLUSIONS: After infrarenal aortic coarctation, action potential duration of left ventricular myocytes is prolonged. This prolongation may be attributed to an increase in calcium current density and a shift of its inactivation variable, together with an increased magnitude and prolonged time course of sodium-calcium exchange current. These current changes are potentially arrhythmogenic.

Action Potentials↗
PubMed1993

Inhibition of herpes simplex virus type 1 DNA polymerase activity by peptides from the UL42 accessory protein is largely nonspecific.

To identify regions in the UL42 protein of herpes simplex virus type 1 which affect viral DNA polymerase activity, a series of 96 overlapping pentadecapeptides spanning the entire 488 amino acids of the UL42 protein were synthesized and tested for their ability to inhibit polymerase activity on a primed single-stranded M13 DNA template. Two assays were used: formation of full-length double-stranded M13 molecules and rate of incorporation of deoxyribonucleoside triphosphates. Peptides from five noncontiguous regions of the UL42 protein were found to inhibit herpes simplex virus type 1 polymerase activity in both the presence and absence of UL42 protein. The most active peptides from each region correspond to amino acids 23 to 38 (peptide 6), 64 to 78 (peptide 14), 89 to 102 (peptide 19), 229 to 243 (peptide 47), and 279 to 293 (peptide 57). By two different methods (DNA mobility shift and DNA precipitation), peptides 14, 19, 47, and 57 were found to bind DNA; they most probably inhibit enzyme activity by this mechanism. Peptide 6 did not bind DNA and must act by some mechanism other than competing for DNA. The inhibitory peptides were also tested for activity against mammalian polymerase alpha and the Klenow fragment of Escherichia coli polymerase. Although some limited specificity was demonstrated (up to 10-fold for peptide 6), all the peptides showed significant activity against both polymerase alpha and E. coli polymerase.

Amino Acid Sequence↗
PubMed1993

Factors associated with genital chlamydial and gonococcal infection in males.

BACKGROUND: Predictors of chlamydia and gonorrhoea can be used to increase the cost-effectiveness and acceptability of screening programmes, and allow targeting of control strategies. METHOD: All men attending an STD clinic in 1988-1990 were offered screening for chlamydia and gonorrhoea, and the test results correlated with a wide range of potential predictors using multiple logistic regression. RESULTS: Of 9622 attenders, 7992 (82.3%) were tested over a total of 10,110 episodes for chlamydia and 10,090 episodes for gonorrhoea, yielding 729 (7.2%) chlamydial and 123 (1.2%) gonococcal infections. Having urethral discharge and/or dysuria, being heterosexual, and STD contact, unmarried, uncircumcised, tattooed and not having had an STD previously were independently associated with chlamydial infection. Having urethral discharge and/or dysuria, being Aboriginal, an STD contact, homosexual, uncircumcised, tattooed and having sex outside the state in the past three months, no steady partner in the past three months and multiple partners in the past month were associated with urethral gonococcal infection. Selective screening criteria for gonorrhoea provided 90% of positives, eliminated the need for 58% of tests and resulted in an increased yield ratio of 2.2 whereas the corresponding outcomes for screening criteria for chlamydia were 93% 20% and 1.2 respectively. CONCLUSIONS: The widespread influence of confounding on potential predictors for both gonorrhoea and chlamydia may provide misleading indicators of risk factors by univariate analysis. In the setting studied the benefits of selective screening for gonorrhoea in men would be substantial, whereas satisfactory criteria for selective screening for chlamydia could not be identified.

Adult↗
PubMed1993

Syphilis and gonorrhoea. Current thinking.

Syphilis and gonorrhoea have become much less common in urban areas in the past decade, although syphilis is still very prevalent among Aborigines. Considerable unnecessary morbidity from these conditions occurs because of deficiencies in management of infected individuals or their sex partners.

Female↗
PubMed1992

Predictors of high risk sexual behaviour in gay and bisexual men.

Evidence of high risk sex between gay men continues to be reported, as does a range of sexual behaviour. Three hundred and sixty-nine homosexually active men from different areas of England were each assessed twice at an an interval of 9 months in order to examine the extent to which a number of social-psychological factors predicted subsequent high risk sexual behaviour. Few of the variables were significantly related to unprotected receptive anal sex in the way that the Health Belief Model predicted, except for some perceptions of costs and benefits of safer sex. However, whether or not men were involved in a regular relationship with a partner was strongly associated with high risk behaviour. The implications of these results are that health education interventions should focus on alerting all men to the social context in which high risk sex is more likely to happen: the regular partnership.

Attitude to Health↗
PubMed1992

The sexual behaviour of bisexual men in relation to HIV transmission.

Relatively little is known about the behaviour of bisexual men which may help in assessing their role in HIV transmission. A sample of 60 behaviourally bisexual men were asked about their sexual behaviour with male and female partners and their perceptions of risk of HIV infection. Only a minority of men engaged in unprotected anal sex with their male partners while two thirds had unprotected vaginal sex with their female partners. This asymmetrical pattern of sexual behaviour reflects a differential perception of risk of HIV infection with male and female partners. A quarter of the men had unprotected penetrative sex with both male and female partners in the previous year. The pattern of risk behaviour varied amongst men living in gay, heterosexual or bisexual contexts.

Adult↗