Search PubMed⌕ Search

Biomedical subjects

M Friedman

Publications and source records attributed to M Friedman.

At least 217 records · Page 12Linked to original sources
PubMed1993

Massachusetts emergency medicine closed malpractice claims: 1988-1990.

STUDY PURPOSE: To describe the characteristics of malpractice claims against emergency physicians and to identify causes and potential preventability of such claims. POPULATION: Malpractice claims closed in 1988, 1989, and 1990 against emergency physicians insured by the Massachusetts Joint Underwriters Association were compared with claims closed from 1980 to 1987 as investigated in our previous study. METHODS: Retrospective review of malpractice claim files by board-certified emergency physicians. RESULTS: The average indemnity and expense per claim were higher in the current study population than in our previous study population (P = .05). Claims in eight high-risk diagnostic areas (chest pain, abdominal pain, fractures, wounds, pediatric fever/meningitis, subarachnoid hemorrhage, aortic aneurysm, and epiglottitis) accounted for 50.8% of claims in this study and 55.5% of total monetary losses. Four claims in this study were related to two instances of failure of an emergency department radiograph follow-up system. The evaluation of patients who were intoxicated contributed to major monetary losses, especially in cases of fractures and head injury. CONCLUSION: Emergency physicians must have a particular awareness of their great risk exposure for missed myocardial infarction. Addition of dictation or voice-activated record generation systems, departmental protocols for radiograph follow-ups, and holding and re-evaluation of the intoxicated patient will help provide systems supports for reducing the liability of individual emergency physicians.

Costs and Cost Analysis↗
PubMed1993

Mechanisms causing coronary microvascular dysfunction following crystalloid cardioplegia and reperfusion.

OBJECTIVE: The aim was to examine the mechanisms of coronary microvascular dysfunction during cardiopulmonary bypass and ischaemic arrest using a crystalloid cardioplegic solution. METHODS: Porcine hearts were arrested with cold hyperkalaemic (K+ = 25 mmol.litre-1) cardioplegic solution for 1 h during cardiopulmonary bypass and then reperfused for 1 h. Selected hearts were arrested but not reperfused. Coronary vessels of non-instrumented pigs were used as controls. In vitro vascular responses of subepicardial and subendocardial arterioles were examined in a pressurised (40 mm Hg) no flow state with video microscopy. RESULTS: Following 1 h of ischaemic cardioplegia, endothelium dependent relaxations of epicardial arterioles to the receptor mediated agent ADP and the non-receptor-mediated agent calcium ionophore A23187 were moderately reduced, and the contractile responses to KCl or the thromboxane A2 analogue U46619 were reduced compared to responses of vessels from control animals. After 1 h of reperfusion, U46619 caused contraction greater than control values, while contraction to KCl and endothelium dependent relaxations to ADP or A23187 were further reduced. Responses of endocardial microvessels to serotonin were slightly more affected by cardioplegia and reperfusion than were epicardial vessels, while the effect on responses of epicardial and endocardial vessels to bradykinin or A23187 were similar. Endothelium independent relaxation to sodium nitroprusside was not altered in any of the experimental groups. The addition of manganese superoxide dismutase to the cardioplegic solution markedly preserved endothelium dependent responses to ADP and A23187 and contractile response to U46619, compared to the responses of vessels from the plain crystalloid cardioplegia group, but had no effect on relaxation to sodium nitroprusside or on contraction to KCl. Five hours of normokalaemic hypothermia (5-10 degrees C) in Krebs buffer had minimal effect on vasodilator responses. Electron microscopy revealed preserved endothelial and smooth muscle cell structure, and focal mononuclear leucocyte-endothelium adherence following cardioplegic arrest and reperfusion. CONCLUSIONS: Ischaemic cardioplegia-reperfusion induced endothelium dependent and direct smooth muscle microvascular dysfunction is at least partially mediated by prolonged exposure of vessels to hyperkalaemia and to the generation of oxygen derived free radicals. Leucocytes probably mediate injury during reperfusion, while hypothermia has minimal effect on recovery of vasomotor function.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1993

Influence of candidates' test selection on pass rates on examinations for certification by the Educational Commission for Foreign Medical Graduates.

BACKGROUND: Parts I and II of the National Board of Medical Examiners (NBME) examination were first offered to graduates of foreign medical schools in 1989 as an alternative to the Foreign Medical Graduate Examination in the Medical Sciences (FMGEMS). This study was designed to determine whether differences in pass rates and scores were related to differences in the populations selecting one or the other examination. METHOD: (1) Combined pass rates on the FMGEMS and NBME in 1989 and 1990 were compared with pass rates in previous years. (2) The proportion of NBME takers in 1989 was compared with the proportion in 1990. (3) Respective pass rates on the FMGEMS and NBME in the first NBME administration in 1989 were compared with pass rates in 1990. (4) The percentage of repeaters taking the FMGEMS was compared with the percentage taking the NBME in 1989 and 1990. (5) The distribution of repeaters by number of previous takes was compared between the FMGEMS and NBME in 1989 and 1990. RESULTS: (1) Combined pass rates were similar to the pass rates of previous years. (2) The proportion of NBME takers declined in 1990. (3) The pass rates for the FMGEMS were higher in both 1989 and 1990, but the difference in pass rates between the two examinations narrowed in 1990. (4) The percentage of repeaters taking the NBME was high in 1989 and declined in 1990. (5) The number of previous takes among repeaters was higher for the NBME than for the FMGEMS in 1989 and became equal in 1990. CONCLUSIONS: Some students probably opted to take the NBME in 1989 in the belief that it might be easier than the FMGEMS, resulting in lower pass rates for the NBME. The NBME pass rates rose in 1990 after the differential pass rates had become public.

Bias↗
PubMed1993

Performances on the NBME I, II, and III by medical students in the problem-based learning and conventional tracks at the University of New Mexico.

BACKGROUND: Problem-based learning curricula are growing in popularity, and questions have been raised about the appropriateness of standardized examinations, such as the National Board of Medical Examiners (NBME) Parts I, II, and III examinations, for assessing students in these new curricula. METHOD: Data on students' performances on the NBME I were analyzed for 508 graduates of the conventional track and 167 graduates of the problem-based Primary Care Curriculum (PCC) track at the University of New Mexico School of Medicine from the classes of 1983-1992; on NBME II, for 447 and 144 graduates, respectively (classes of 1983-1991); and on NBME III, for 313 and 100 graduates, respectively (classes of 1983-1989). The analyses also included data on the students' total Medical College Admission Test (MCAT) scores, undergraduate science grade-point averages (SGPAs), and admission subgroups within tracks. The statistical methods included analysis of covariance, Student's t-test, and the Fisher exact test. RESULTS: The students who had requested the PCC track but had been randomized into the conventional track had the highest mean scores on all the study variables (for 34 students, 521 on the NBME I, and for 19 students, 551 on the NMBE III). The high-risk students who had requested but had not been accepted into the PCC track seemed to benefit from the highly structured conventional track with regard to their NMBE I performances (467 for 18 students). The PCC students--both those who had been randomized into the PCC and those who had been selected into the PCC--had significantly lower mean scores on the NBME I (455 for 85 students and 463 for 82 students compared with 505 for the 439 students who chose the conventional track), but significantly higher mean scores on the NBME III (521 for 38 students and 522 for 62 students compared with 483 for the seven high-risk students and 487 for the 276 students who chose the conventional track). For both tracks, strong relationships were found among the scores on the three NBME examinations. For the PCC students, significantly weaker relationships were found between mean SGPAs and mean scores on the NBME I, II, and III. For both tracks, MCAT scores, especially in the lowest and highest ranges, were most predictive of performances on the NBME I and II. CONCLUSION: In the short run, the more teacher-centered and structured conventional curriculum better prepared the students for the NBME I, while in the long run, the more student-centered problem-based curriculum better prepared the students for the NBME III:

Curriculum↗
PubMed1993

Nodal size of metastatic squamous cell carcinoma of the neck.

The preoperative use of computed tomographic (CT) scanning continues to be the best diagnostic method for preoperative detection of metastatic neck disease. Current accepted criteria for CT diagnosis of nodal disease are not uniform, although nodal size, nodal grouping, and central necrosis correlate strongly with malignancy. To assess the relationship of nodal size and malignancy, a multicenter study was designed to evaluate the nodes from 100 neck dissections. Sixty-nine positive neck dissections were analyzed, and every node was measured. The relationship of central necrosis was also compared with node size. Our results showed that CT scanning continues to provide a reliable picture of the histologic status of lymph nodes. Using the criterion of central necrosis or node size larger than 1 cm, only 7% of necks had nodal disease that would have been missed by CT interpretation. This study supports the continued use of preoperative CT evaluation for metastatic neck disease.

Carcinoma, Squamous Cell↗
PubMed1993

Chemical nature and immunotoxicological properties of arachidonic acid degradation products formed by exposure to ozone.

Ozone (O3) exposure in vivo has been reported to degrade arachidonic acid (AA) in the lungs of rodents. The O3-degraded AA products may play a role in the responses to this toxicant. To study the chemical nature and biological activity of O3-exposed AA, we exposed AA in a cell-free, aqueous environment to air, 0.1 ppm O3, or 1.0 ppm O3 for 30-120 min. AA exposed to air was not degraded. All O3 exposures degraded > 98% of the AA to more polar products, which were predominantly aldehydic substances (as determined by reactivity with 2,4-dinitrophenylhydrazine and subsequent separation by HPLC) and hydrogen peroxide. The type and amount of aldehydic substances formed depended on the O3 concentration and exposure duration. A human bronchial epithelial cell line (BEAS-2B, S6 subclone) exposed in vitro to either 0.1 ppm or 1.0 ppm O3 for 1 hr produced AA-derived aldehydic substances, some of which eluted with similar retention times as the aldehydic substances derived from O3 degradation of AA in the cell-free system. In vitro, O3-degraded AA induced an increase in human peripheral blood polymorphonuclear leukocyte (PMN) polarization, decreased human peripheral blood T-lymphocyte proliferation in response to mitogens, and decreased human peripheral blood natural killer cell lysis of K562 target cells. The aldehydic substances, but not hydrogen peroxide, appeared to be the principal active agents responsible for the observed effects. O3-degraded AA may play a role in the PMN influx into lungs and in decreased T-lymphocyte mitogenesis and natural killer cell activity observed in humans and rodents exposed to O3.

Aldehydes↗
PubMed1993

Applications of three-dimensional CT imaging in head and neck pathology.

The advantages of three-dimensional (3-D) imaging in the diagnosis of developmental and posttraumatic craniofacial abnormalities is well established. A brief review of this role of 3-D imaging is presented, followed by a discussion of the use of 3-D imaging in various head and neck disorders.

Facial Bones↗
PubMed1992

Statistical model to determine the relationship of response and survival in patients with advanced ovarian cancer treated with chemotherapy.

BACKGROUND: A statistically appropriate analysis of the association between survival and response measures in patients with ovarian cancer could help to define the role of response rate in planning, monitoring, and interpreting the results of clinical trials. PURPOSE: This study was designed to investigate the relationship between antitumor response determined by clinical or pathological means and survival in patients with advanced ovarian cancer with no previous treatment. We focused on avoiding the limitations of the usual approach of comparing durations of survival for patients responding to therapy with those for nonresponders. METHODS: A new meta-analytic statistical model we developed was used to analyze data from 26 randomized clinical trials published between 1975 and 1989. Our model incorporates intra-study and inter-study sources of variability in the estimates of response and survival. The study also addresses the methodological problems of evaluating response as a surrogate end point and the relevance of this association to clinical decision making and the design of clinical trials. RESULTS: For 13 studies in which response was pathologically assessed, an improvement in surgically documented complete response rate was associated with an increase in median survival. A similar but apparently smaller effect was found for the association between objective clinical response and median survival in the 25 studies reporting these data. CONCLUSIONS: These results suggest that therapeutic measures must produce large improvements in clinical response rates to achieve meaningful effects on median survival. Improvement in surgically documented complete response rate appears to be more strongly associated with increased median survival and, hence, might be used for interim monitoring in clinical trials, but the role of second-look procedures in clinical management is controversial.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Differences in arachidonic acid metabolism by human myelomonocytic cell lines.

The production of arachidonic acid metabolites by the HL60, ML3, and U937 human phagocyte cell lines was determined after incubation with interferon-gamma (IFN-gamma, 500 U/ml) or vehicle for 4 days. Cells were prelabeled with tritiated arachidonic acid, [3H]AA, for 4 h, and media supernatants were analyzed by high-performance liquid chromatography. None of the cell lines produced [3H]AA metabolites in large amounts during an unstimulated, basal release period (30 or 60 min). In response to 10 microM calcium ionophore A23187 incubation (30 min), undifferentiated and IFN-gamma-differentiated HL60 cells formed both cyclooxygenase products (thromboxane and prostaglandins) and lipoxygenase products (leukotrienes and hydroxyeicosatetraenoic acids). In contrast to the HL60 cells, IFN-gamma-differentiated U937 cells formed primarily cyclooxygenase products and undifferentiated and IFN-gamma-differentiated ML3 cells did not form any [3H]AA metabolites in response to A23187. These results indicate the need to be careful in selecting a cell line for use in a phagocyte assay system when cyclooxygenase and/or lipoxygenase products could influence the assay results.

Antigens, CD↗
PubMed1992

Physicochemical properties of albumin microspheres determined by spectroscopic studies.

The interactions of a family of fluorescein dyes of varying hydrophobicities and polarizabilities (as well as those of several model drugs) with native and colloidal denatured albumin systems from various sources were monitored spectroscopically. The use of colloidal denatured albumin systems allowed direct determination of spectral shifts induced by the interactions of the dyes or drugs with the albumins. Large bathochromic shifts were observed upon interaction of hydrophobic dyes or drugs with bovine and human albumin systems. Egg albumin systems, on the other hand, did not induce such shifts. The hydrophobicities of the albumin surfaces estimated using bathochromic shifts were in the order bovine greater than human greater than egg, in agreement with literature values. The changes in absorbances of the dyes or drugs following interaction with the albumins allowed estimation of the polarizabilities of the albumins; these were in the order bovine greater than human greater than egg. The similar interactions of dyes and model drugs with albumin microspheres suggest that fluorescein dyes serve as excellent probes of the physicochemical state of denatured albumin systems and as good models for studying drug interaction with albumin microspheres. These studies also indicate that it may be possible to predict drug uptake by albumin microspheres from physicochemical properties of the drugs and carriers. Such predictions would be of great potential value for screening the suitability of carriers, especially for drugs which are highly sensitive to the preparation conditions of the microspheres, such as heating and cross-linking agents.

Adsorption↗
PubMed1992

Effect of ozone on platelet activating factor metabolism in phorbol-differentiated HL60 cells.

The mechanisms of ozone (O3) toxicity in the lung may involve the formation of lipid inflammatory mediators. We have previously demonstrated that exposure to O3 in vitro results in increased accumulation and release of platelet activating factor (PAF) in the macrophage-like cell line HL60 differentiated with phorbol ester (dHL60). In the present study we have examined possible biochemical mechanisms responsible for the O3-induced increase in PAF levels in dHL60 cells. Specifically, we studied the effect of O3 on phospholipase A2 (PLA2), acetyltransferase, acetylhydrolase, and reacylation activities. dHL60 cells were exposed to 1.0 ppm O3 or air alone. O3 exposure was found to significantly decrease dHL60 cell acetylhydrolase activity by 36%. Additional experiments demonstrated that extracellular acetylhydrolase activity, but not intracellular acetylhydrolase activity, was inhibited by O3 exposure of dHL60 cells. O3 exposure resulted in a small (13%) but statistically significant reduction in reacylation activity in dHL60 cells. In addition, a significant (22%) contribution of PLA2 activation to the O3-induced increase in PAF levels was also found. Basal and calcium ionophore-induced acetyltransferase activity was found to be unaffected by exposure of dHL60 cells to O3. These data suggest that in vitro exposure to O3 affects both synthetic and degradative pathways of PAF metabolism in dHL60 cells.

Acetylation↗
PubMed1992

Absence of genotoxicity of potato alkaloids alpha-chaconine, alpha-solanine and solanidine in the Ames Salmonella and adult and foetal erythrocyte micronucleus assays.

To assess whether reported toxicities of potato-derived glycoalkaloids could be the result of interactions with cellular DNA, the genotoxic effects of alpha-solanine, alpha-chaconine and solanidine were studied, using the Ames test (Salmonella strains TA98 and TA100), the mouse peripheral blood micronucleus test and the mouse transplacental micronucleus test. The Ames test for mutagenicity with alpha-solanine was weakly positive in TA100 with S-9 activation (29 revertants per millimole per plate). However, pooled data from duplicate tests gave a negative effect. Pooled data from two experiments with alpha-chaconine gave a weak positive response in TA98 without microsomes (17 revertants per millimole per plate). The micronucleus tests for clastogenicity using male mouse and foetal blood were negative. The absence of mutagenicity and clastogenicity suggests lack of damage to intracellular DNA for potato alkaloid toxicity.

Animals↗
PubMed1992

Partial amino acid sequence of potato solanidine UDP-glucose glucosyltransferase purified by new anion-exchange and size exclusion media.

Solanidine UDP-glucose glucosyltransferase (SGT) is involved in the biosynthesis of steroidal glycoalkaloids in potatoes. This enzyme is present at an extremely low level, is inherently unstable, and copurifies with the major storage protein patatin during isolation. We describe an improved method for isolating SGT from greening potato peel using two new chromatographic supports, Macro-Prep 50 Q anion-exchange and Superdex 75HR size exclusion media, under medium-pressure conditions at room temperature. The enzyme preparation was further resolved by SDS-PAGE and the proteins transferred to PVDF membrane (Immobilon-P). Two protein bands corresponding to active forms of SGT (36 and 37 kDa) were excised and cleaved with cyanogen bromide in trifluoroacetic acid. The resultant peptide mixtures were then separated by Tricine-SDS-PAGE and transferred to a PVDF membrane (Pro-Blott). The two major peptide bands observed in both digests (17 and 19 kDa) were sequenced. Identical N-terminal sequences were obtained from the 19-kDa peptides from both digests.

Amino Acid Sequence↗
PubMed1992

Adsorption of fluorescein dyes on albumin microspheres.

The surface characteristics of bovine and egg albumin microspheres were examined using four anionic dyes; sodium fluorescein, eosin, erythrosin, rose bengal, and the cationic dye rhodamine B. The adsorption isotherms of the dyes on unloaded albumin microspheres exhibited Langmuir behavior for dilute solutions of rose bengal, erythrosin, and eosin, suggesting monolayer formation in the initial stages of the sorption process. The adsorption capacity of the microspheres for the dyes (k2) and the affinity constants of the dyes for the microspheres (k1) were found to depend on both the polarizability and the hydrophobic properties of the dye, presumably reflecting the heterogeneous character of the microsphere surface. Further, the extent of sorption at higher dye concentrations was found to depend on the ability of the dye to form stable aggregates inside the microspheres and on environmental long-range forces acting at these sites. At both low and high dye concentrations, the amount adsorbed to the microsphere surface increased with increasing hydrophobicity of the dyes. The lowest adsorption was observed for the nonsubstituted dye fluorescein, whereas the most hydrophobic dye used, rose bengal, was completely adsorbed onto the microsphere surface. The data suggest that the bovine albumin microsphere surfaces are highly hydrophobic and less porous than egg albumin microsphere surfaces.

Adsorption↗