Search PubMed⌕ Search

Biomedical subjects

R Cohen

Publications and source records attributed to R Cohen.

At least 199 records · Page 11Linked to original sources
PubMed1996

Contingent negative variation (CNV) and determinants of the post-imperative negative variation (PINV) in schizophrenic patients and healthy controls.

A slowly rising cortical potential shift with negative polarity following the imperative stimulus of a forewarned reaction time task, the 'post-imperative negative variation' (PINV), is regularly observed in schizophrenic patients but not in controls. The topography of the PINV suggests that it may originate in frontal cortical regions. We used a task designed to test two putative prefrontal cortical functions: working memory and processing of ambiguity. Nineteen patients with a chronic schizophrenic disorder and 19 control subjects matched for age, sex, and education participated in two experimental sessions. The EEG was recorded from frontal, central, temporal, and parietal leads over both hemispheres using a DC amplifier. PINV amplitudes were generally larger in patients than in controls. If the result of comparing physical features of the two successively presented stimuli (warning and imperative stimulus) was ambiguous rather than clear, an augmentation of the PINV amplitudes was seen in both groups. If this comparison required high rather than low involvement of working memory functions, PINV amplitudes were augmented in schizophrenic patients only. Scalp distribution of the PINV indicated a left-hemisphere fronto-central PINV maximum in patients, and a right-hemisphere predominance in controls, which was larger following ambiguous stimulus comparisons. These results suggest that ambiguity during the comparison of physical features of successively presented stimuli may be a general factor of the PINV in schizophrenic patients and healthy controls. Augmented involvement of working memory functions, presumably subserved by the prefrontal cortex, specifically affected the fronto-centrally predominant PINV in schizophrenic patients. This result is compatible with the hypothesis of prefrontal cortical dysfunctions in schizophrenia.

Adult↗
PubMed1996

Unesterified long chain fatty acids inhibit the binding of single chain urokinase to the urokinase receptor.

The interaction of single chain urokinase with its receptor accelerates plasminogen activator activity on cell surfaces and induces intracellular signalling in several cell types. To date, no physiologic inhibitor of this binding has been identified. We report that the binding of scuPA to its cellular receptor is inhibited by long chain fatty acids such as oleic acid (C18, delta 9) at physiological plasma concentrations. Inhibition of single chain urokinase binding to human trophoblastic cells by long chain fatty acids was dose-dependent and saturable. Fifty percent of the binding was inhibited at an oleic acid concentration of 27 microM, while inhibition was maximal (75%) at 150 microM oleic acid. The inhibitory potency of oleic acid was unaffected by fatty acid free albumin or human plasma. Inhibition of single chain urokinase binding by free fatty acid analogues was critically dependent on chain length (> C14 required for inhibition) and was proportional to the extent of unsaturation. Only the fraction of specific scuPA binding to trophoblasts that was dependent on uPAR was susceptible to inhibition by oleic acid, while binding of scuPA to vitronectin, thombospondin, and the alpha 2-macroglobulin receptor/low-density lipoprotein-related receptor was not. [3H]Oleic acid bound specifically to recombinant soluble uPAR in a 1:1 molar ratio in the presence or absence of plasma and totally blocked its specific binding to a cell line expressing glycosyl phosphatidylinositol-linked single chain urokinase. These results indicate that oleic acid and other unsaturated long chain free fatty acids may serve as physiologic regulators of proteolytic events and intracellular signalling that depend upon the interaction of urokinase with its receptor.

Animals↗
PubMed1996

Ethylene glycol ethers and risks of spontaneous abortion and subfertility.

Potential reproductive effects from occupational exposures to ethylene glycol ethers (EGE) are of concern since these organic solvents have been used widely in industry, and their reproductive toxicity has been well documented in animal studies. For determination of whether occupational exposure to EGE was associated with increased risks of spontaneous abortion and subfertility (i.e., taking more than 1 year of unprotected intercourse to conceive), a retrospective cohort study was conducted among workers at two semiconductor manufacturing plants in the eastern United States in 1980-1989 as part of a larger evaluation of reproductive health. Reproductive and occupational histories were obtained from interviews of semiconductor manufacturing workers and spouses. Assessment of potential exposure to mixtures containing EGE (none, low, medium, and high) was based on reported processes and company records. There were 1,150 pregnancies to semiconductor manufacturers, 561 to female employees and 589 to wives of male employees. Among female manufacturers, potential exposure to mixtures containing EGE was associated with increased risks of spontaneous abortion (relative risk in the high exposure group = 2.8; 95% confidence interval (CI) 1.4-5.6) and subfertility (odds ratio in the high exposure group = 4.6; 95% CI 1.6-13.3). Both of these risks exhibited a dose-response relation with potential EGE exposure (p for trend = 0.02). Among spouses of male manufacturers potentially exposed to mixtures containing EGE, there was no increased risk of spontaneous abortion, but there was a nonsignificant increased risk of subfertility (odds ratio in the high exposure group = 1.7; 95% CI 0.7-4.3).

Abortion, Spontaneous↗
PubMed1996

Laparoscopic fundoplication 1 month prior to lung transplantation.

Upper midline laparotomy in the presence of pulmonary failure is often complicated by a prolonged period of mechanical ventilation postoperatively. We report the successful performance of laparoscopic fundoplication, without ventilatory support, in a woman with end stage pulmonary disease and resting hypercarbia, one month prior to lung transplantation.

Female↗
PubMed1996

Neurological soft signs in schizophrenia: assessment and correlates.

A German version of the Neurological Evaluation Scale (NES) was administered to 143 schizophrenic patients, 45 of them being severly chronic and disabled. Seventy-eight alcohol-dependent inpatients and 57 healthy volunteers were tested as control groups. Neurological soft signs (NSS) were rated with convincing agreement. Schizophrenic patients are more impaired on all scales than healthy controls. The chronic, severly disabled schizophrenic patients are more impaired compared with the main group of schizophrenic patients and both control groups. A significant difference between the main group of schizophrenic patients and alcohol-dependent patients was only found for the subscale "Motor Coordination". Compared with healthy controls the alcohol-dependent patients show a higher NES total score. The NES total score was related to the relative width of the third ventricle. Total score and subscales were correlated consistently with the level of cognitive functioning as measured by the Raven Standard Progressive Matrices and various neuropsychological tests presumably sensitive to dysfunctions of the prefrontal cortex. The NSS were related to positive as well as to negative symptoms, the correlations with negative symptoms being confined to items of "Cognitive Disorganization". This close association of psychomotor and cognitive dysfunctions may be seen as related to the frequently discussed dysfunctions of the prefrontal cortex or the neurointegrative deficit postulated by Meehl.

Adult↗
PubMed1996

Teaching effectiveness of the advanced trauma life support program as demonstrated by an objective structured clinical examination for practicing physicians.

Although the Advanced Trauma Life Support (ATLS) course is now taught internationally, its teaching effectiveness still requires confirmation. The Objective Structured Clinical Examination (OSCE) reliably assesses clinical performance by utilizing standardized patients. An OSCE of eight 15 minute trauma patient stations and two 40 item MCQ tests were used to test the teaching effectiveness of the ATLS program in 32 practicing physicians who applied for an ATLS program in Trinidad and Tobago. The physicians were randomly assigned to an ATLS group (n = 16) that completed the ATLS course and a non-ATLS group (n = 16). Before and after the ATLS course, all physicians completed MCQ tests and trauma OSCE. Mean (+/- SD) OSCE scores (standardized to 20) ranged from 9.8 +/- 1.7 to 10.0 +/- 1.7 and 9.5 +/- 1.8 to 10.8 +/- 1.3 in the ATLS and non-ATLS groups, respectively, prior to the ATLS course (NS). Post-ATLS OSCE scores ranged from 15.9 +/- 1.7 to 17.6 +/- 1.7 in the ATLS group (p < 0.05 compared to pre-ATLS) and 9.5 +/- 1.4 to 10.1 +/- 1.3 in the non-ATLS group, which did not improve their OSCE scores. Adherence to priorities was graded 1 to 7 with the pre-ATLS grades of 1.7 +/- 0.6 (ATLS) and 1.8 +/- 0.7 (non-ATLS) and post-ATLS grades of 6.4 +/- 1.1 (ATLS) and 2.1 +/- 0.6 (non-ATLS). Organized approach to trauma was graded 1 to 5 with pre-ATLS grades of 1.6 +/- 0.5 (ATLS) and 1.7 +/- 0.6 (non-ATLS) and post-ATLS grades of 4.5 +/- 0.6 (ATLS) and 1.9 +/- 0.6 (non-ATLS). Pre-ATLS MCQ scores (%) were similar: 53.1 +/- 8.4 (ATLS) and 57.3 +/- 5.4 (non-ATLS), but post-ATLS scores were greater in the ATLS group: 85.8 +/- 7.1 (ATLS) and 64.2 +/- 3.6 (non-ATLS). Our data support the teaching effectiveness of the ATLS program among practicing physicians as measured by improvement in OSCE scores, adherence to trauma priorities, maintenance of an organized approach to trauma care, and cognitive performance in MCQ examinations.

Clinical Competence↗
PubMed1996

The impact of gender on the choice of surgery as a career.

BACKGROUND: The objective of the survey was to examine factors affecting career choice by medical students. METHODS: A questionnaire was distributed to the 245 fourth-year students at the University of Toronto, sampling qualities of importance in specialties, the importance of role models, attitudes toward surgery, and specialty match results. RESULTS: There was a 69% return rate. Males were more likely to choose a surgical career than were females (27% versus 10%, respectively; P = 0.01). Males were more likely to identify technical challenge, earning potential, and prestige (P < 0.01) whereas females were more likely to identify residency conditions, part-time work, and parental leave availability as important qualities in a specialty (P < 0.01). Females were less likely to take surgical electives (P < 0.001) and more likely to identify a lack of role models (P < 0.003). Students agreed that surgeons have rewarding careers (79%) and earn more (64%); however, they do not agree that surgeons enjoy spending time with patients (10%) or have rewarding family lives (5%). CONCLUSIONS: Fewer females than males were found to consider or choose a surgical career, possibly due to differences in qualities of importance in specialties, availability of role models, and exposure through electives.

Adult↗
PubMed1996

Teaching effectiveness of surgeons.

BACKGROUND: Evaluation of clinical teaching is essential for feedback to teachers, and for reliable and valid data for the purpose of promotion and tenure. METHODS: The teaching effectiveness of 43 surgeons was evaluated continuously over a 9-year period. Stability of Teaching Effectiveness Scores (TES) over the 9-year period, correlation with age, and the changes after academic promotion were analyzed. RESULTS: A total of 3,750 evaluations were completed. The average of 10 evaluations per surgeon per year gave an intraclass correlation of 0.65. The mean TES did not show any significant change over the 9 years. The majority of the "good" and "average" surgeons maintained their TES ratings, and most of the "poor" group improved their TES. The age of the surgeon was not a factor. Most surgeons had a decrease in their TES after academic promotion. CONCLUSIONS: A reliable system of teaching evaluation was achieved. Teaching scores were stable over time for good and average teachers, whereas the poor teachers tended to improve their scores.

Adult↗
PubMed1996

Comparison of triamcinolone acetonide nasal inhaler with astemizole in the treatment of ragweed-induced allergic rhinitis.

BACKGROUND: Few clinical trials have directly compared the efficacy of antihistamines with topical nasal corticosteroids. OBJECTIVE: The study was performed to compare the efficacy and safety of triamcinolone acetonide nasal spray at a dose of 110 micro g in each nostril once daily with 10 mg of oral astemizole once daily for the treatment of seasonal allergic rhinitis. METHODS: A multicenter, double-blind, parallel-group study was conducted in 239 patients who were randomized to receive either triamcinolone acetonide or astemizole. A 5-day, drug-free, lead-in period was followed by 4 weeks of double-blind treatment. One hundred four patients treated with triamcinolone acetonide and 105 patients treated with astemizole could be evaluated. RESULTS: Overall, triamcinolone acetonide was more effective than astemizole in reducing total nasal symptoms, nasal stuffiness, nasal itching, and sneezing (p </= 0.01). Triamcinolone acetonide was superior to astemizole at weeks 1, 2, and 3 in reduction of the total nasal symptom score (p </= 0.0401) and in reduction of nasal stuffiness (p </= 0.05). Improvements in individual nasal symptoms (itching, postnasal drip, runny nose, and sneezing) were greater for triamcinolone acetonide at week 2 (p </= 0.01). Ocular symptoms improved from baseline in both groups. When pollen counts were correlated to mean nasal rhinitis scores, the triamcinolone acetonide group showed continued improvement from week 1 to week 2 in nasal symptoms when pollen counts were at their highest. During the same period, patients treated with astemizole failed to show improvement from week 1 to week 2. This study demonstrated that once daily administration of triamcinolone acetonide was more effective than astemizole for controlling nasal symptoms of seasonal allergic rhinitis, especially during the peak pollination period.

Administration, Intranasal↗
PubMed1996

Performance-based assessment of clinical ethics using an objective structured clinical examination.

PURPOSE: To further examine the objective structured clinical examination (OSCE) as a performance-based assessment method for clinical ethics. METHOD: In the spring of 1993, a volunteer sample of 88 final-year medical students from all five Ontario medical schools took a four-station OSCE that used standardized patients and involved decisions to forego life-sustaining treatment. Performance was scored on a checklist of behaviors unique to each case. Data were analyzed for reliability using intraclass correlation coefficients and the Spearman-Brown prophecy formula. RESULTS: Reliability of the test was only .28 as a result of a low average inter-station correlation of .07. To achieve a test reliability of .8, 41 stations (almost seven hours of testing time) would be required. CONCLUSION: Because of its low test reliability, the OSCE is not a feasible stand-alone method for summative evaluation of clinical ethics. This performance-based evaluation method should be combined with other, more reliable evaluation methods. The OSCE has promise for formative evaluation.

Educational Measurement↗
PubMed1996

Attrition of cognitive and trauma management skills after the Advanced Trauma Life Support (ATLS) course.

OBJECTIVE: To test the attrition of cognitive and trauma management skills among practising physicians after the Advanced Trauma Life Support (ATLS) course. DESIGN, MATERIALS, AND METHODS: Sixty practising physicians who completed the ATLS course had comparative assessment of cognitive skills (with multiple choice questions, MCQ) pre-ATLS, immediately post-ATLS, at 6 months (group A), 2 years (group B), 4 years (group C), and 6 years (group D) after the course. Trauma management skills were also compared using eight Objective Structured Clinical Examination (OSCE) trauma stations completed by the four groups of physicians. MEASUREMENTS AND MAIN RESULTS: Pre-ATLS MCQ scores (54.2 +/- 4.2 to 59.8 +/- 5.3%) and immediately post-ATLS MCQ scores (85.9 +/- 5.1 to 87.7 +/- 5.3%) were similar in all four groups. Follow-up MCQ scores were 77.8 +/- 3.6% at 6 months 70.6. +/- 1.9% at 2 years, 69.4 +/- 1.7% at 4 years, and 68.9 +/- 2.0% at 6 years. OSCE scores out of a maximum of 20 were 16.8 +/- 0.3 at 6 months, 13.9 +/- 0.1 at 2 years, 12.0 +/- 0.1 at 4 years, and 11.9 +/- 0.1 at 6 years. Adherence-to-priorities scores (maximum, 7) were 6.6 +/- 0.2 at 6 months, 6.8 +/- 0.1 at 2 years, 6.6 +/- 0.1 at 4 years, and 6.6 +/- 0.1 at 6 years. Organized-approach scores (maximum, 5) were 4.8 +/- 0.1 at 6 months, 4.6 +/- 0.2 at 2 years, 4.7 +/- 0.2 at 4 years, and 4.6 +/- 0.2 at 6 years. Using the MCQ 80% pass mark criterion, at least 50% of physicians fail by 6 months and all fail this cognitive test thereafter. CONCLUSIONS: Whereas cognitive and trauma management skills decline after the ATLS, these skills are maintained at similar levels between 4 and 6 years after ATLS. A 50% failure rate occurs within 6 months and maximum attrition of cognitive skills occurs within 2 years of ATLS completion. Major principles of adherence to priorities and maintenance of an organized approach to trauma care are preserved for at least 6 years after ATLS.

Adult↗
PubMed1996

Six-day amoxicillin vs. ten-day penicillin V therapy for group A streptococcal tonsillopharyngitis.

OBJECTIVE: To compare the efficacy and safety of amoxicillin (50 mg/kg/day divided twice daily) for 6 days and penicillin V (45 mg/kg/day divided into three doses/day) for 10 days in children with group A streptococcal (GAS) tonsillopharyngitis. METHODS: In a prospective, comparative, open, randomized, multicenter trial, children were scheduled to return for visits 4 days (main end point) and 1 month after the completion of treatment for clinical and bacteriologic assessment. Total DNA restriction fragment length polymorphism was used to compare pre- and posttreatment GAS isolates. RESULTS: Between September, 1993, and February, 1995, 321 children (161 amoxicillin, 160 penicillin V) were enrolled, among whom 318 (160 amoxicillin, 158 penicillin V) were evaluable for safety, and 277 were evaluable for efficacy. Four days after the completion of treatment, pretreatment GAS were eradicated from 118 of the 141 children receiving amoxicillin (83.7%) and 116 of the 136 (85.3%) taking penicillin. One month after the outset of treatment, bacteriologic relapses were observed in 9.9% (n = 11) of the children receiving amoxicillin and 5.7% (n = 6) of those treated with penicillin V, bacteriologic recurrences in 5 and 3 patients, respectively. Adverse events related to the study medications were reported in 4 patients in the amoxicillin group and 8 in the penicillin V group. Drug-related adverse events leading to treatment discontinuation occurred in 3 patients, all in the penicillin V group. Compliance, based on diary cards and the weight of study drugs returned, was significantly better in the amoxicillin group. CONCLUSIONS. The efficacy and safety of amoxicillin (50 mg/kg/day twice daily) for 6 days were not statistically different from those of penicillin (45 mg/kg/d three times a day) for 10 days in the treatment of GAS tonsillopharyngitis.

Adolescent↗
PubMed1996

Evaluating communication skills in the OSCE format: reliability and generalizability.

In most objective structured clinical examinations (OSCEs), communication skills are assessed as an 'add-on' to history-taking stations, rather than in stations designed to assess communication skills in the broadest sense. This study investigated the feasibility of developing such stations. In part one, 60 clinical clerks and 36 residents were rated in four 10-min emotionally charged situations portrayed by standardized patients. Inter-rater reliability was demonstrated (r = 0.59-0.63) and a highly significant effect of educational level was found. Generalizability between communication stations was low (0.17-0.20). Several explanations for poor generalizability, including poor discrimination as a result of low score variance and the confounding effect of content knowledge, were addressed in part 2. Ninety-five final-year medical students participated in an OSCE in which six 10-min encounters examined the students' ability to manage difficult emotional situations such as fear, anxiety, mania, sadness, confusion and anger. Half the students encountered a patient with moderate emotional symptoms and half an extreme emotional state. For difficult stations, students' scores were lower and standard deviation higher, suggesting that manipulating difficulty increases score variance and potentially discrimination. However, a strong interaction was found between difficulty and station content, and communication scores were highly correlated with content. Scenarios which created major communication difficulties (such as mania) resulted in much larger differences in scores between the easy and difficult versions. Communication OSCE stations can be created with acceptable reliability including difficult cases which address communication skills beyond simple history taking. Nevertheless, a generalizable set of communication skills remains elusive.

Canada↗
PubMed1996

The impact of performance uncertainty on the postimperative negative variation.

In a delayed matching-to-sample task, the impact of clear or ambiguous go versus clear no-go signals on the post-imperative negative variation (PINV) was examined in 11 patients with a chronic schizophrenic disorder (DSM-III-R) and in a control group of 13 healthy subjects matched to the patient sample by age, sex, and education. Size and spatial position of a visual S2 had to be matched to one of two visual patterns in the S1 presented 4 s earlier. In 96 trials, the S2 was identical in size with one of the two patterns of S1 (clear matching). These trials varied pseudorandomly, with 60 trials in which the S2 was of intermediate size. On a randomly interspersed additional 48 trials, an S2 differing in color and shape signaled no-go. The electroencephalogram was recorded from Fz, Cz, Pz, F3, F4, C3, C4, P3, and P4. Although groups did not differ in contingent negative variation amplitude, the PINV was generally more pronounced in patients than in controls. In both groups, ambiguity of the to-be-matched S2 produced larger PINV amplitudes; the no-go signal elicited only a small PINV. Differential effects of ambiguity and no-go on PINV amplitude and its scalp distribution suggest that "performance" and "action" uncertainty contribute to PINV generation and that thresholds for both effects are reduced in schizophrenics.

Acoustic Stimulation↗