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Biomedical subjects

M Cohen

Publications and source records attributed to M Cohen.

At least 613 records · Page 34Linked to original sources
PubMed1989

Correlates of certification in family medicine in the billing patterns of Ontario general practitioners.

There is conflicting evidence as to whether physicians who are certified in family medicine practise differently from their noncertified colleagues and what those differences are. We examined the extent to which certification in family medicine is associated with differences in the practice patterns of primary care physicians as reflected in their billing patterns. Billing data for 1986 were obtained from the Ontario Health Insurance Plan for 269 certified physicians and 375 noncertified physicians who had graduated from Ontario medical schools between 1972 and 1983 and who practised as general practitioners or family physicians in Ontario. As a group, certificants provided fewer services per patient and billed less per patient seen per month. They were more likely than noncertificants to include counselling, psychotherapy, prenatal and obstetric care, nonemergency hospital visits, surgical services and visits to chronic care facilities in their service mix and to bill in more service categories. Certificants billed more for prenatal and obstetric care, intermediate assessments, chronic care and nonemergency hospital visits and less for psychotherapy and after-hours services than noncertificants. Many of the differences detected suggest a practice style consistent with the objectives for training and certification in family medicine. However, whether the differences observed in our study and in previous studies are related more to self-selection of physicians for certification or to the types of educational experiences cannot be directly assessed.

Canada↗
PubMed1989

Calcium chelator Quin 2 prevents hydrogen-peroxide-induced DNA breakage and cytotoxicity.

Exposure of cultured Chinese hamster ovary (CHO) cells to hydrogen peroxide results in the production of extensive DNA breakage which can be prevented by the intracellular calcium chelator Quin 2. This effect occurs at Quin 2 AM concentrations as low as 0.1 microM and is maximal at 1 microM. Addition of the extracellular calcium chelator, EGTA, does not affect the level of DNA breakage generated by H2O2. Quin 2 also significantly reduces cellular toxicity caused by the oxidant. Experiments with spin-trapping techniques demonstrate that Quin 2 does not affect the formation of hydroxyl radicals generated by the action of Fe2+ on H2O2. Quin 2 at high concentrations, similar to those reached within the cell, actually enhanced generation of hydroxyl radical in the absence of other iron chelators under our experimental conditions. These results suggest that H2O2 or H2O2-derived radicals do not directly induce DNA strand breakage in intact mammalian cells; rather, these radicals may disturb intracellular Ca2+ homeostasis which results in secondary reactions ultimately leading to DNA strand breakage. In addition to strand breakage, membrane and protein oxidation probably contribute to the cytotoxic effect of H2O2.

Aminoquinolines↗
PubMed1989

The infrared emission bands. III. Southern IRAS sources.

We present airborne 5-8 micrometers spectra of southern IRAS sources which reveal strong polycyclic aromatic hydrocarbon (PAH) emission features. The good correlation between the bands, in particular the dominant 6.2 and "7.7" micrometers features, strongly imply a common carrier, reinforcing the PAH hypothesis. However, small but detectable spectral variations exist. Planetaries have a distinctly different ratio of I(6.2)/I(7.7) than other nebulae, accompanied by a redward shift in the actual wavelength of the "7.7" micrometers peak. Further, we have detected a new feature, previously predicted from laboratory spectra of PAH molecules, at 5.2 micrometers in many of these sources. Spectra of two rare [WC 10] planetary nebular nuclei indicate a very prominent plateau of emission, linking the 6.2 and 7.7 micrometers bands. Several of our sources show definite evidence for emission structure between 14 and 23 micrometers in their IRAS Low-Resolution Spectral Atlas spectra: we attribute this structure to PAH bands. too. We have defined the "generic" spectrum of emission bands relating the mean intensities of each band to that of the strongest, near 7.7 micrometers. We have added three more planetary or protoplanetary nebulae to our correlation between 7.7 micrometers band intensity and nebular gas phase C/O ratio, namely NGC 6302, HR 4049, and the highly carbon-rich [WC 10] nucleus, CPD--56 degrees 8032. For the latter we have determined a ratio for C/O of approximately 4.8 from IUE observations. The good correlation between the intensity ratio of the "7.7" micrometers feature relative to the far-infrared dust continuum and nebular C/O also supports a carbonaceous carrier for these emission features.

Aircraft↗
PubMed1989

New emission features in the 11-13 micron region and their relationship to polycyclic aromatic hydrocarbons.

If the "11.3 microns" emission feature seen in the spectra of many planetary nebulae, H II regions, and reflection nebulae is due to polycyclic aromatic hydrocarbons (PAHs), then additional features should be present between 11.3 and 13.0 microns (885 and 770 cm-1). Moderate-resolution spectra of NGC 7027, HD 44179, IRAS 21282+5050, and BD + 30 degrees 3639 are presented which show that the "11.3 microns" feature actually peaks at 11.22 microns (891 cm-1). The spectra also show evidence of new emission features near 11.9 and 12.7 microns (840 and 787 cm-1). These are consistent with an origin from PAHs and can be used to constrain the molecular structure of the family of PAHs responsible for the infrared features. The observed asymmetry of the "11.3 microns" band is consistent with the slight anharmonicity expected in the C--H out-of-plane bending mode in PAHs. Laboratory experiments show that the intensity of this mode relative to the higher frequency modes depends on the extent of molecular "clustering." The observed strengths of the "11.3 microns" interstellar bands relative to the higher frequency bands are most consistent with the features originating from free molecular PAHs. The intensity and profile of the underlying broad structure, however, may well arise from PAH clusters and amorphous carbon particles. Analysis of the 11-13 microns (910-770 cm-1) emission suggests that the molecular structures of the most intensity emitting free PAHs vary somewhat between the high-excitation environment in NGC 7027 and the low-excitation but high-flux environment close to HD 44179. Finally, a previously undetected series of regularly spaced features between 10 and 11 microns (1000 and 910 cm-1) in the spectrum of HD 44179 suggests that a simple polyatomic hydride is present in the gas phase in this object.

Astronomical Phenomena↗
PubMed1989

Balloon valvuloplasty in adult aortic stenosis: determinants of clinical outcome.

STUDY OBJECTIVE: To determine the clinical variables affecting outcome after balloon aortic valvuloplasty. DESIGN: Longitudinal follow-up of consecutive case series. PATIENTS: Consecutive sample of 36 patients with severe calcific aortic stenosis, and without active infection or left ventricular mural thrombus. INTERVENTIONS: Percutaneous transluminal dilatation of the aortic valve until the peak gradient was reduced by 50% or a maximal balloon size was used. Hemodynamic measurements taken before and after dilatation. MEASUREMENTS AND MAIN RESULTS: Thirty-three patients had a successful dilatation. Eighty-nine percent (95% confidence interval [CI]. 74% to 97%) improved symptomatically at 2 weeks, but by 26 weeks only 56% (CI, 35% to 76%) remained improved (P = 0.0078). Mortality rates were high at 8 (9%) and 26 (28%) weeks. Predictors of adverse events included left ventricular ejection fraction (P = 0.04, r = 0.46), pulmonary artery systolic pressure (P = 0.048, r = 0.65), pulmonary vascular resistance (P = 0.008, r = 0.69), and right ventricular end-diastolic pressure (P = 0.009, r = 0.43) at 8 weeks and all these factors except left ventricular ejection fraction at 26 weeks. These clinical outcomes were unrelated to other cardiac or pulmonary diseases. CONCLUSIONS: Symptomatic improvement is only temporary in many patients undergoing balloon aortic valvuloplasty, and the mortality rate in the mid-term follow-up period is high. Valve surgery remains the treatment of choice for aortic stenosis in the adult.

Aged↗
PubMed1989

Rhabdomyosarcoma of the oral and paraoral region.

Oral rhabdomyosarcoma (RMS) was studied by analysis of eight such cases which presented over a 25-year period. Rhabdomyosarcoma was the fourth most common oral sarcoma (7.5%) from this period after osteosarcoma (32%), fibrosarcoma (19%), and chondrosarcoma (9%). In patients younger than 20 years, RMS was the second most common sarcoma (six cases) after osteosarcoma (ten cases). Combined analysis with 113 further cases documented in the literature showed the majority of cases (71.2%) were embryonal. The alveolar subtype was considered a distant second in frequency (12.3%) even though the pleomorphic subtype was apparently more common (16.4%). However, the pleomorphic cases were diagnosed before histologic criteria were established to discern this entity from other pleomorphic sarcomas and this data is probably unreliable. Site predilections were found for the soft palate, maxillary sinus and alveolus, posterior mandibular region, cheek and lip and possibly tongue. The gingiva and floor of mouth were uncommon sites. There was a predilection for occurrence in the first two decades with a decline in the third decade. Documentation of recent cases treated with a multidisciplinary approach indicated that lesions in the oral soft tissues have a good prognosis; 17 of 21 such cases showed no evidence of disease after a mean follow-up period of 7.2 years (SD = 4.4). In contrast, four of five cases in the posterior mandible resulted in death after a mean period of 1.1 years (SD = 0.3).

Adolescent↗
PubMed1989

A comparison of clinically and empirically derived MMPI groupings in low back pain patients.

Two methods of grouping MMPI scales were employed with 271 patients who were attending a Back Clinic at a university hospital. One method involved clinically derived decision rules, while the other utilized a multivariate clustering procedure. Five subgroups of patients were identified with each method. Both procedures showed subgroup differences in terms of pretreatment pain intensity, activity limitations, McGill affective scores, and physician ratings of degree of functional impairment; the elevated subgroups showed more dysfunction. Follow-up comparisons revealed that, regardless of the classification procedure used, the elevated subgroups showed poorer response to treatment. Only the clinically derived groupings had significant differences in chronicity of pain and total scores on the McGill Pain Questionnaire. On the other hand, only the statistically based system showed significant differences on age and marital status. Furthermore, only the statistical system identified subgroups of male patients that predicted followup pain intensity decreases in a manner that indicated clinical usefulness.

Adult↗
PubMed1989

Neuropathological abnormalities in developmental dysphasia.

The brain of a 7-year-old girl with developmental dysphasia who died of complications of infectious mononucleosis was examined grossly and histologically. The neuropathological studies revealed atypical symmetry of the plana temporale and a dysplastic gyrus on the inferior surface of the left frontal cortex along the inferior surface of the sylvian fissure. These anomalies are likely related to midgestation, the period of neuronal migration from the germinal matrix to the cerebral cortex, and are consistent with a neurodevelopmental cause of developmental dysphasia.

Aphasia↗
PubMed1989

Dual connection of the left anterior descending coronary artery to the left and right coronary arteries.

Origin of the left anterior descending coronary artery from the right coronary artery is a well-described but rare congenital coronary anomaly. In this report, we describe two cases in which the mid left anterior descending coronary artery is connected to the right coronary artery through an intraseptal connecting vessel, while the proximal left anterior descending coronary artery originates normally from the left main coronary artery. This previously unreported pattern suggests partial persistence of the peritruncal ring, which occurs during normal embryologic development of the coronary circulation. Even though it is classically described as an epicardial structure, the vascular pattern in our cases suggests that the peritruncal ring may have an intramural segment in some individuals.

Adult↗
PubMed1989

Gynecologic screening examinations: does the obstetrician-gynecologist's spouse comply?

The practicing obstetrician-gynecologist has certainly moved toward more active teaching and encouragement of preventive medical measures during the past decade. The purpose of this study was to determine how these measures espoused by the practitioner are applied in the physician's family setting. To accomplish this, 5000 questionnaires were sent to actively practicing obstetrician-gynecologists. Questions pertained to health habits as well as social and demographic issues. The results revealed that preventive medical practices, which have a high impact on morbidity and mortality, were not practiced to a significant degree by the spouses of obstetrician-gynecologists. Approximately 17% of the spouses did not have yearly Papanicolaou smears. Women older than 55 years of age were less likely to have this screening test than their younger cohorts. Only 65% perform breast self-examination, and 36% did not have screening mammography performed when recommended. In the postmenopausal group, 57% of the spouses did not receive estrogen replacement therapy, whereas 32% had both estrogen- and progesterone replacement therapy and 11% took estrogen alone. Contraceptive measures used by respondents indicated essentially equal distribution among methods available. The majority of the physicians who responded indicated they did not smoke (84%), did not use illegal drugs (99%), and used alcohol occasionally or not at all (71%).

Adult↗