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Biomedical subjects

C Abraham

Publications and source records attributed to C Abraham.

At least 55 records · Page 3Linked to original sources
PubMed1993

In search of a psychology of safer-sex promotion; beyond beliefs and texts.

Belief and attitudinal change are important to the promotion of safer sexual behaviour. However, the individual decision-making psychology implicit in belief-change models provides only a partial picture of the determinants of sexual behaviour. A broader psychological understanding emphasizing the complex social skills involved in regulating sexual interaction is advocated. A discourse analysis critique of the viability of characterizing individuals' psychology on the basis of verbal responses is discussed and it is noted that psychological models linking such responses to underlying beliefs and cognitions must be based on measures which accurately predict health behaviour. It is concluded that an interactive model incorporating personal, interpersonal and situational constraints on sexual behaviour could be used to design effective programmes addressing barriers to HIV protection. Such interventions would promote communication and sexual negotiating skills and could be included in school curricula. This would have radical implications for sex education, shifting its theoretical basis from biology to social psychology and its methods from information-giving to participation and practice.

Adult↗
PubMed1993

Intraoperative measurement of intraocular pressure in vitrectomized aphakic air-filled eyes using the Tono-Pen XL.

The Tono-Pen XL (Bio-Rad, Santa Ana, CA) was compared with manometer readings for intraoperative measurement of intraocular pressure (IOP) in 40 eyes of 40 consecutive patients after vitrectomy, lensectomy, and fluid-air exchange. Tono-Pen readings corresponding to manometer readings of 10, 20, 30, 40, and 50 mmHg were obtained in a masked fashion with a randomized sequence of manometer readings. A correlation was obtained between the manometer and Tono-Pen readings (r = 0.96 in emmetropic eyes and r = 0.93 in myopic eyes). The regression curve that represents the calibration curve of Tono-Pen in terms of the manometer readings for air-filled vitrectomized eyes was obtained. Any Tono-Pen reading can be easily translated into the corresponding manometer reading by referring to the curve. The Tono-Pen can therefore be effectively used to accurately determine intraoperative IOP in eyes undergoing vitrectomy, lensectomy, and fluid-air exchange.

Adolescent↗
PubMed1993

Behavioural sciences and the real world: report of a community interview scheme for medical students.

A community interview scheme was designed to provide preclinical medical students with an opportunity to investigate the role of social and psychological variables in patient care and gain insight into interpersonal aspects of the interview process. Evaluation of the scheme showed that students and community interviewees found their participation valuable. Eighty per cent of interviewees were willing to take part in the scheme in the following year. The strongest predictor of willingness to participate was interviewees' rating of the extent to which they had enjoyed the experience. Students valued the opportunity to meet 'real people', to explore social and psychological determinants of health and illness and to develop communication skills. A significant positive change in perceived interviewing competence was observed. It is suggested that the scheme might be further developed by using feedback from interviewees to provide students with evidence of both their own skill development and the benefits of self-disclosure to the patients involved.

Behavioral Sciences↗
PubMed1993

The antagonist properties of S 11978 on 5HT3 receptors in N1E-115 neuroblastoma cells.

The effects of the novel antagonist S 11978 (Endo-7-[(8-methyl-8-azabicyclo[3,2,1]-3-octyl)oxycarbonyl] benzo[b] thiophene) on 5HT3 receptors were examined in N1E-115 mouse neuroblastoma x rat glioma hybrid cells, with radioligand binding and whole cell patch clamp techniques. The 5HT3 receptor ligand [3H] quipazine was displaced by ICS 205-930, GR 38032F and S 11978 with KI values of 2.25 nM, 36.5 nM and 1.75 nM respectively. Electrophysiological studies showed that S 11978 is a potent 5HT3 antagonist: IC50 values for inhibition of 5HT-induced inward current by ICS 205-930, GR 38032F and S 11978 were 0.22 nM, 0.63 nM and 0.43 nM respectively at a holding potential of -65 mV. It is concluded that S 11978 is a potent, high affinity 5HT3 receptor antagonist.

Animals↗
PubMed1992

Health beliefs and promotion of HIV-preventive intentions among teenagers: a Scottish perspective.

Beliefs concerning the spread of the human immunodeficiency virus (HIV) and preventive behaviors were examined in a sample of 351 sexually active Scottish teenagers. A postal questionnaire, including measures of variables specified by the health belief model (HBM) and preventive intentions, was employed. The relation between HBM measures and reported endorsement of HIV-preventive intentions was investigated. Results indicated that, in general, respondents intended to use condoms with new sexual partners. The majority also intended to carry condoms if they thought they might have sex with a new partner and to ask potential partners about their previous sexual history. Multiple-regression analyses showed that measures of health beliefs, gender, age, sexual experience, and previous condom use accounted for 17.8% to 24.3% of the variance in reported preventive intentions. Perceived barriers to preventive behaviors were found to be important predictors. However, the overall pattern of results raised questions concerning the adequacy of the HBM as a model of the determinants of HIV-preventive intentions, and the need for an extended model is discussed. Separate analyses were conducted for men and women and for 16- and 18-year-olds, and the implications for modeling intention formation in these subgroups are considered. The relevance of these findings to HIV-preventive campaigns is also discussed.

Adolescent↗
PubMed1992

Context and content: the impact of school-leaving and school-based health education on AIDS-relevant cognitions.

A survey examined health beliefs and intentions among 690 16-18 year-olds in Dundee. Respondents in the younger cohort (n = 363) were classified according to their educational situation (at school vs left) and self-reports of having received AIDS/HIV-relevant health education. Both remaining in school and receiving AIDS/HIV-relevant health education had independent beneficial effects, but the effects of leaving school also interacted with sex of respondent and with amount of relevant education received prior to leaving. Males' and females' reliance on mass media and other information sources diverged once they left school, indicating that males who leave school early are most likely to disregard useful or important information regarding AIDS. Consistent with this finding, leaving school reduced the difference between males' and females' intention to use condoms with a new partner. The beneficial impact of having previously received AIDS/HIV-relevant education on beliefs concerning the controllability of the epidemic and on feeling worried about everyday contact with a person with HIV/AIDS, was most marked among those who had left school. The results are discussed in terms of their implications for health education strategies.

Adolescent↗
PubMed1991

Young people learning about AIDS: a study of beliefs and information sources.

A study of the views of Scottish teenagers and undergraduates on health education issues relevant to human immunodeficiency virus (HIV) spread is reported. A sample of 1008 young people (690 teenagers and 318 students) returned a postal questionnaire designed to measure a range of relevant cognitions. These included levels of concern, perceived knowledge, perceived vulnerability, perceived seriousness, recall of health education campaigns, preferred information sources and views on the discussion of HIV/AIDS with significant others. Low levels of perceived vulnerability, high levels of recall for national campaigns, and discrepancies between used and credible sources of information are reported. Cohort and gender differences and correspondences with American and Australian studies are discussed. The implications of these findings for future AIDS education campaigns are also considered.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Ca2+ channel inhibition by a new dihydropyridine derivative, S11568, and its enantiomers S12967 and S12968.

Biochemical and electrophysiological techniques were used to describe the Ca2+ channel blocking properties of a new dihydropyridine derivative, S11568 (+/-)- ([(amino-2-ethoxy)-2-ethoxy]methyl)-2-(dichloro-2',3'-phenyl)-4- ethoxy-carbonyl-3-methoxycarbonyl-5-methyl-6-dihydro-1,4-pyridine and its enantiomers S12967 ((+)-S11568) and S12968 ((-)-S11568). In binding studies, S11568 and S12968 displaced specifically bound [3H]PN 200-110 from cardiac and vascular smooth muscle preparations with potencies of 5.6-51 nM, respectively. S12967 was 6- to 18-fold less potent than S12968. A good correlation was found between the IC50 value for the inhibition of 45Ca2+ uptake by A7r5 aortic smooth muscle cells and binding data. Whole-cell patch clamp studies in both guinea-pig ventricular myocytes and A7r5 cells yielded similar results. At holding potential (VH) -50 mV, S12968 inhibited L-type Ca2+ current with an IC50 value near 70 nM, 2- to 3-fold more potently than S11568 and 30-fold more potently than S12967. With VH -100 mV, all three compounds were less potent, with IC50 values ranging from 500 nM to 3 microM. These results demonstrate conclusively that S12968 is the more active enantiomer. Furthermore, the pronounced voltage dependence of its actions in vitro suggests that in vivo it could exhibit good selectivity for vascular smooth muscle over cardiac muscle.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

Surgical alternatives in the treatment of life-threatening ventricular arrhythmias.

We present our experience in the treatment of life-threatening ventricular tachycardia using electrophysiologically guided surgery (97 patients), automatic implantable cardioverter defibrillator (AICD) (42 patients), and orthotopic heart transplantation (15 patients). Eighty-three percent of these patients had ischemic and 17%, nonischemic heart disease. Our results of electrophysiologically directed surgery show an early mortality of 10% and a recurrence of 5% in the ischemic group. In the nonischemic group, the recurrence was 45%. The AICD was implanted in 31 patients with ischemic heart disease, in 5 with ventricular dysplasia, and in 6 with dilative cardiomyopathy, the ejection fractions ranging from 12% to 65%, with a mean of 30%. Early and late mortalities were 5% and 19%, respectively. The AICD was effective in all patients. Survival rate at 1 year was 83% +/- 6.4%. Thirteen of 15 patients have survived heart transplantation for 3-20 months (mean: 11 months). Ejection fractions prior to transplantation ranged from less than 10% to 34% (mean: 16%). We conclude that electrophysiologically guided surgery is highly effective in most cases of ischemia-related ventricular tachycardia. The AICD is considered a palliative alternative in patients with either poor ventricular function, no electrophysiological substrate, or multimorphological tachycardia. Heart transplantation has to be considered especially in young patients in whom progression of the underlying disease can be anticipated. Bridging by AICD is possible when transplantation is not immediately available or recommendable.

Adolescent↗
PubMed1986

X-ray diffraction from intraneuronal paired helical filaments and extraneuronal amyloid fibers in Alzheimer disease indicates cross-beta conformation.

Information about the structure of the paired helical filaments (PHF) that accumulate within human neurons and the amyloid fibers that accumulate in the extracellular spaces between neurons in Alzheimer disease has so far depended on electron microscopy of thin-sectioned or negatively stained material. To determine the protein conformation of these abnormal fibers, we have obtained x-ray diffraction patterns from unfixed human brain fractions highly enriched in PHF and from purified amyloid cores isolated from senile plaques. The predominant x-ray scatter evident from both types of samples, either wet or dry, is a sharp reflection at 4.76-A spacing and a diffuse one at about 10.6-A spacing. These features are characteristic of a beta-pleated sheet type of protein conformation. In doubly oriented dried pellets of PHF fractions, the two reflections are accentuated at right angles to each other and the arc at 4.76-A spacing is in the fiber direction indicating a cross-beta conformation. From the integral widths of the reflections we estimate the cross-beta crystallite to be about 80 A long in the fiber direction and about 40 A thick. These dimensions correspond to approximately four pleated sheets, each of which consists of approximately 16 hydrogen-bonded polypeptide chains running normal to the fiber direction. The cross-beta conformation of PHF and amyloid fibers that we have found from x-ray diffraction is in contrast to the predominant alpha-helical coiled-coil conformation of the neurofilaments with which they share epitopes and from which they have been postulated to derive.

Alzheimer Disease↗
PubMed1986

Intravenous treatment of autoimmune hemolytic anemia with very high dose gammaglobulin.

Autoimmune hemolytic anemia (AIHA) has been considered to be unresponsive to intravenous gammaglobulin (IVGG) at the doses that are effective in immune thrombocytopenic purpura and autoimmune neutropenia (usually 2 g/kg total dose). This study reports the use of a higher dose (5 g/kg total dose over 5 days) in four severe cases of AIHA which resulted in a sustained remission in two patients, a transient response in the third, and a failure in the forth patient. These data suggest that larger quantities of IVGG may be needed in this disease, possibly because the reticuloendothelial system appears to be enlarged in AIHA patients.

Adult↗
PubMed1984

Alzheimer's disease: immunoreactivity of neurofibrillary tangles with anti-neurofilament and anti-paired helical filament antibodies.

The origin of the paired helical filaments (PHF) that accumulate in human neurons during aging and in Alzheimer's disease and their relationship to normal neurofilaments remain unclear. The observation that a rabbit antiserum to highly enriched PHF fractions specifically labeled PHF in Alzheimer neurofibrillary tangles but showed no reaction with neurofilaments or other normal cytoskeletal proteins led us to compare this antiserum to two monoclonal antibodies, RT97 and BF10, previously found to cross-react with tangles and with the 210,000 and 155,000 mol. wt. neurofilament proteins, respectively. Both alpha-PHF serum and the neurofilament monoclonals strongly immunolabel almost all neurofibrillary tangles in Alzheimer cortical sections. Double-immunolabeling studies show that both reagents recognize the same tangles and usually show identical patterns of staining of intraneuronal fibrous material. Following prolonged extraction of cortex in sodium dodecyl sulfate, a step which removes normal neurofilaments but leaves PHF intact, almost all isolated tangles retain strong immunoreactivity with alpha-PHF serum at an intensity which is slightly reduced from that in cortical sections. In contrast, only a small number of isolated tangles are stained strongly by RT97 and BF10; most show much decreased or no reactivity with these monoclonal neurofilament antibodies. This differential immunoreactivity was confirmed by double-labeling studies. Tangles prepared under gentle extraction conditions show strong reactivity with alpha-PHF antibodies but again only a small number are strongly labeled by RT97 and BF10. We conclude that neurofibrillary tangles in Alzheimer's disease are heterogeneous as regards their filamentous content and contain both antigens cross-reacting with neurofilaments and antigens which are apparently unique to PHF and not shared with normal neurofilaments.

Alzheimer Disease↗
PubMed1984

Microtubule-associated protein 2: monoclonal antibodies demonstrate the selective incorporation of certain epitopes into Alzheimer neurofibrillary tangles.

Neurofibrillary tangles (NFT) are the principal structural alteration of neuronal cell bodies in Alzheimer disease as well as in normal aging of the human brain. While the ultrastructure of these intraneuronal lesions has been extensively studied, the biochemical composition of the fibers comprising the NFT is unknown. We report the production of three monoclonal antibodies against the microtubule-associated protein 2 (MAP-2), one of which intensely labels Alzheimer NFT. All three antibodies specifically recognize MAP-2 on immunoblots and stain brain tissue in a characteristic dendritic pattern. The three antibodies are directed against at least two different antigenic sites on the MAP-2 molecule, and one appears to recognize a phosphorylation site on MAP-2. That only one of the three antibodies immunolabels NFT suggests that the formation of the tangle involves some modification of the MAP-2 molecule. Our findings suggest that one aspect of Alzheimer-type neurofibrillary pathology is an aggregation of MAP-2 or MAP-2 fragments with altered neurofilamentous elements present in NFT. Normal interactive function, which putatively occurs between neurofilaments and MAP-2, may thus be disrupted in Alzheimer disease.

Alzheimer Disease↗