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Biomedical subjects

S Barrett

Publications and source records attributed to S Barrett.

At least 73 records · Page 4Linked to original sources
PubMed1993

Alpha 1-adrenoceptor-mediated inhibition of cellular cAMP accumulation in neonatal rat ventricular myocytes.

We studied adrenergic regulation of cellular cAMP in neonatal rat ventricular myocytes. Since cAMP content depends on synthesis, breakdown and egress, the contribution of each of these mechanisms was assessed. In the presence of the phosphodiesterase inhibitor 3-isobutyl-l-methylxanthine, cAMP accumulation stimulated by the beta-adrenoceptor agonist (-)-isoprenaline was diminished when the mixed alpha + beta adrenoceptor agonist (-)-noradrenaline was coincubated with (-)-isoprenaline. Moreover, adenylyl cyclase activation stimulated by (-)-isoprenaline was decreased by (-)-noradrenaline and by the selective alpha 1-adrenoceptor agonists (-)-phenylephrine and methoxamine, suggesting that alpha-adrenoceptor agonism regulates cAMP metabolism through its effect on the synthetic pathway. Evidence for alpha 1-adrenoceptor mediation of this response was enhancement of (-)-noradrenaline-induced cAMP generation by the selective alpha 1-adrenoceptor antagonist terazosin (10 nmol/l). The selective alpha 2-adrenoceptor antagonist yohimbine (10 nmol/l) had no effect. The alpha 1-adrenoceptor mediated depression of (-)-isoprenaline-stimulated cAMP generation and adenylyl cyclase activation was prevented by terazosin and in separate experiments markedly enhanced by pertussis toxin pretreatment, suggesting involvement of a guanine-nucleotide regulatory protein in this process. Occupation of the alpha 1-adrenoceptor by (-)-noradrenaline did not accelerate the rate of cAMP breakdown in the absence of phosphodiesterase inhibition. Furthermore, there was no enhancement of total phosphodiesterase activity by (-)-noradrenaline in the presence of (-)-propranolol. By contrast, pertussis toxin pretreatment augmented phosphodiesterase activity. Neither pertussis toxin nor (-)-noradrenaline increased cAMP egress. We conclude that in rat neonatal cardiac myocytes agonist occupation of the alpha 1-adrenoceptor inhibits beta-adrenoceptor stimulated cAMP accumulation most likely by coupling to a guanine nucleotide inhibitory protein.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Smoking cessation and severity of disease: the Coronary Artery Smoking Intervention Study.

We tested the effectiveness of an individually delivered behavioral multicomponent smoking intervention (SI) against offering advice only (AO) to 267 patients after coronary arteriography. After 6 months, 51% of AO patients and 62% of SI patients reported abstinence. Validated rates were 34% and 45% for AO and SI patients, respectively. Logistic regression analyses, controlling for severity of illness, stage of change, and self-efficacy, among other variables, showed that, at 6 months, the SI had the most effect for patients with more severe coronary artery disease (CAD) who had been admitted with a myocardial infarction (95% confidence interval = 2.05, 124.85). At 12 months, only severity of disease mediated SI effects (95% confidence interval = 3.10, 58.00). Similar results were seen for cotinine-validated cessation. This study confirms the effectiveness of individually administered SI for more seriously ill patients with CAD and raises questions as to how to better intervene with those individuals with less severe disease.

Attitude to Health↗
PubMed1992

Detection and recognition of stop consonants by normal-hearing and hearing-impaired listeners.

This study examined the possibility that hearing-impaired listeners, in addition to displaying poorer-than-normal recognition of speech presented in background noise, require a larger signal-to-noise ratio for the detection of the speech sounds. Psychometric functions for the detection and recognition of stop consonants were obtained from both normal-hearing and hearing-impaired listeners. Expressing the speech levels in terms of their short-term spectra, the detection of consonants for both subject groups occurred at the same signal-to-noise ratio. In contrast, the hearing-impaired listeners displayed poorer recognition performance than the normal-hearing listeners. These results imply that the higher signal-to-noise ratios required for a given level of recognition by some subjects with hearing loss are not due in part to a deficit in detection of the signals in the masking noise, but rather are due exclusively to a deficit in recognition.

Adult↗
PubMed1992

[Clinical assessment of a group of children with juvenile rheumatoid arthritis receiving long-term treatment with oral gold salt].

The authors assess the efficacy of gold salt treatment for juvenile rheumatoid arthritis. The study was carried out on 16 children suffering from mono-pauciarticular, polyarticular and systemic arthritis. Treatment consisted of the administration of auranofin alone in a group of 8 children and auranofin associated to corticosteroids in a second group of 8 children. A marked improvement in clinical conditions was observed with slight transitory side effects at follow-up after 12 and 24 months.

Adolescent↗
PubMed1989

[Therapeutic strategy in the acute onset phase of infantile rheumatoid arthritis. Comparison of the main anti-inflammatory agents].

The effectiveness of some anti-inflammatory drugs has been compared in a series of 35 patients suffering from infant rheumatoid arthritis at onset and at the third month of disease. The results show that the clinical response to the various therapeutic protocols differs with the protocol and the stage of the disease in consideration, that disease monitoring in the early stage benefits from the serological examinations and that there is a low incidence of significant side-effects.

Acute Disease↗
PubMed1984

The prevalence of hepatitis B serological markers in emergency physicians.

Hepatitis B (HBV) is a well-documented, increasing occupational hazard to those in the medical and dental professions. While the prevalence of markers of hepatitis B in the general population in the United States is approximately 3% to 5%, the prevalence in the health professions has been found to be higher. The prevalence of markers in 260 emergency physicians, consisting of teaching and nonteaching staff and emergency medicine residents, was the focus of this study. Two hundred fourteen participants had not received hepatitis B vaccine; 46 had received the vaccine. Hepatitis B surface antigen (HBsAg), surface antibody (anti-HBs) and core antibody (anti-HBc) were tested. The overall prevalence of markers in the nonvaccinated group was 11.7% (25/214). Forty-one of 46 participants (89%) who had received hepatitis B vaccine demonstrated anti-HBs, evidence of immunity to hepatitis B. Thirty-nine of them had anti-HBs alone, and two had anti-HBs and anti-HBc. Of the five vaccinees who failed to demonstrate anti-HBs, one demonstrated anti-HBc alone. There was no statistically significant difference between the three groups in prevalence or type of markers. The prevalence of hepatitis B serological markers in this survey of emergency physicians was two and a half to four times that of the general population. Because of the increased risk of exposure to hepatitis B virus, early immunization against this disease through the use of hepatitis B vaccine should be considered by physicians in the practice of emergency medicine.

Emergency Medicine↗
PubMed1982

Immunopathology of psoriasis: a comparison with other parakeratotic lesions.

Characteristic in vivo binding of IgG and C3 to the stratum corneum of psoriatic lesions has been implicated as a significant event in the pathogenesis of the disease. Immunofluorescent findings of psoriatic lesions are compared with other parakeratotic and nonparakeratotic lesions. Parakeratotic lesions studied include verrucae vulgares in patients with psoriasis, verrucae vulgares in patients without psoriasis, actinic keratoses and lichen simplex chronicus. Psoriatic lesions and other parakeratotic lesions demonstrate similar immunopathological phenomena within the involved stratum corneum: (1) A high percentage of the lesions stain positively with one or more of the immunoglobulins (IgG, IgM and IgA). (2) No predominance of any immunoglobulin class is found. (3) The predominant sites of immunoglobulin deposition are within the regions of parakeratosis. (4) C3 deposition is found in a high percentage of the lesions and is present at the sites of immunoglobulin binding. By contrast only a small percentage of nonparakeratotic lesions display stratum corneum fluorescence. These data are consistent with macromolecular leakage through the lesional microvasculature and high affinity binding of immunoglobulins by parakeratotic stratum corneum. Similar immunofluorescent findings in psoriatic lesions and nonpsoriatic parakeratotic lesions suggest that immunoglobulin binding in psoriatic lesional stratum corneum is not a significant event in the pathogenesis of psoriatic lesions.

Antigen-Antibody Reactions↗
PubMed1982

Penile ulcer in heroin abuse: a case report.

The rarity of reported cases of cutaneous ulcerations in heroin abusers prompts this report of a 25-year-old man with a painless, slightly necrotic and purulent ulcer of the dorsal shaft of the penis. The differential diagnosis of the lesion and cutaneous manifestations of heroin abuse are reviewed. To our knowledge, this is only the second reported case of penile ulcer from heroin injection.

Adult↗
PubMed1979

Cell surface heterogeneity of human blood neutrophils and monocytes.

Until recently, human blood neutrophils (PMN) and monocytes have been considered to be homogeneous cell populations. However, much evidence has accumulated on their functional heterogeneity. This functional heterogeneity suggests the existence of different subsets of myeloid cells analogous to T and B subsets of lymphoid cells. The goal of this study was to investigate this question of myeloid subsets by examining myeloid cells for cell surface reactivity for IgG and complement (C). Normal PMN and monocytes were examined from 60 subjects for the presence of two types of IgG-Fc receptors and two activated C components, C3b and C3d. Most PMN and monocytes showed Fc receptor activity for rabbit IgG (Fc-R). In addition, the majority of monocytes but very few PMN reacted with human IgG (anti-Rh0) coated Rh-positive erythrocytes (Fc-H). Most PMN and monocytes showed C receptor reactivity for C3b, but only a minor subpopulation of both myeloid cells had C3d receptors. These data provide evidence that human blood myeloid cells may be composed of subsets with different membrane marker reactivities.

Complement C3↗