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Biomedical subjects

M Friedman

Publications and source records attributed to M Friedman.

At least 253 records · Page 14Linked to original sources
PubMed1991

Formation, nutritional value, and safety of D-amino acids.

The extent of racemization of L-amino acid residues to D-isomers in food proteins increases with pH, time, and temperature. The nutritional utilization of different D-amino acids vary widely, both in animals and humans. In addition, some D-amino acids may be deleterious. For example, although D-phenylalanine is nutritionally available as a source of L-phenylalanine, high concentrations of D-tyrosine inhibit the growth of mice. The antimetabolic effect of D-tyrosine can be minimized by increasing the L-phenylalanine content of the diet. Similarly, L-cysteine has a sparing effect on L-methionine when fed to mice; however, D-cysteine does not. The wide variation in the utilization of D-amino acids is exemplified by the fact that D-lysine is not utilized as a source of L-lysine, whereas the utilization of D-methionine as a source of the L-isomer for growth is dose-dependent, reaching 76% of the value obtained with L-methionine. Both D-serine and the mixture of L-L and L-D isomers of lysinoalanine induce histological changes in the rat kidneys. D-tyrosine, D-serine, and lysinoalanine are produced in significant amounts under the influence of even short periods of alkaline treatment. Unresolved is whether the biological effects of D-amino acids vary, depending on whether they are consumed in the free state or as part of a food protein. Possible, metabolic interaction, antagonism, or synergism among D-amino acids in vivo also merits further study. The described results with mice complement related studies with other species and contribute to the understanding of nutritional and toxicological consequences of ingesting D-amino acids. Such an understanding will make it possible to devise food processing conditions to minimize or prevent the formation of undesirable D-amino acids in food proteins and to prepare better and safer foods.

Amino Acids↗
PubMed1991

Hepatic ornithine decarboxylase induction by potato glycoalkaloids in rats.

The induction of hepatic ornithine decarboxylase (ODC) activity in rat livers by the potato glycoalkaloids alpha-solanine, alpha-chaconine, and their aglycone solanidine, has been studied. Ip administration of alpha-solanine at 7.5, 15 and 30 mg/kg body weight produced markedly elevated enzyme activity at 4 hr after treatment, with a linear dose response. The increase was four-fold at the lowest dose administered to 12-fold at the highest. ODC activity was measured at 1, 2, 3, 4, 5, 6, 8, and 24hr after alpha-solanine was given. A statistically significant increase in enzyme activity was evident at 3 hr after treatment; maximal activity occurred at 5 hr and was approximately 12 times greater than the dimethylsulphoxide (DMSO) control level. Elevated activities persisted for several hours, decreasing to about one-third of the maximal level at 8 hr. The relative effects of alpha-solanine, alpha-chaconine and solanidine on ODC activities were studied at 4 hr using an equimolar dose of 17 mM/kg body weight. ODC activity induced by alpha-chaconine was higher than that induced by alpha-solanine; the latter activity was two-thirds that of the former. The aglycone solanidine did not induce any increase in activity compared with the DMSO control. ODC activity with dexamethasone, a glucocorticoid, at 4 mg/kg body weight, followed a pattern similar to that of alpha-solanine. However, maximal activity occurred slightly earlier at 4 hr after treatment. The results show that the extent of induced ODC activity depends on the structure of the potato alkaloid.

Animals↗
PubMed1991

Developmental toxicology of potato alkaloids in the frog embryo teratogenesis assay--Xenopus (FETAX).

Potatoes frequently contain growth inhibitors and toxic compounds including digestive enzyme inhibitors, lectins and glycoalkaloids. The literature suggests that Solanum alkaloids have the ability to induce neurological damage such as spina bifida and other malformations. As part of a programme of improvement in the safety of potatoes using molecular plant genetics and parallel food safety evaluation, we evaluated the effect of several potato glycoalkaloids and aglycones in the frog embryo teratogenesis assay--Xenopus (FETAX) with and without metabolic activation by Aroclor 1254-induced rat liver microsomes. The data suggest that the glycoalkaloid alpha-chaconine is teratogenic and more embryotoxic than alpha-solanine, in terms of the median lethal concentration (LC50) after 96 hr of exposure, the concentration inducing gross terata in 50% of the surviving frog embryos (96-hr EC50, malformation), and the minimum concentration needed to inhibit the growth of the embryos. Since these two compounds differ only in the nature of the carbohydrate side chain attached to the 3-OH group of solanidine, the side chain appears to be an important factor in governing teratogenicity. The aglycones demissidine, solanidine and solasodine were less toxic than the glycosides alpha-chaconine and alpha-solanine. The in vitro teratogenesis assay should be useful for: (a) predicting the teratogenic potential of solanaceae alkaloids, glycoalkaloids and related natural products; and (b) facilitating experimental approaches to suppress plant genes and enzymes that control the biosynthesis of the most toxic compounds.

Abnormalities, Drug-Induced↗
PubMed1991

Rethinking critical issues in performance assessment.

The recent interest of medical schools and licensure organizations in establishing performance assessment methods in medical education presents new challenges to medical educators. The problems encountered in establishing the reliability and validity properties of performance assessment necessitate rethinking the accepted definitions of reliability and validity. The authors examine the relationship between Classical Test Theory and job performance. They discuss several critical issues: the meanings of reliability and validity in performance assessment and the balance between them (including simple versus complex behaviors), stability of performance, specific versus generic abilities, and the role of experts in clinical performance assessment. The authors call for a critical appraisal of applying Classical Test Theory to the assessment of job-related behaviors.

Clinical Competence↗
PubMed1991

Assessment of emergency medicine: a comparison of an experimental objective structured clinical examination with a practical examination.

An emergency medicine and trauma programme was implemented at Ben Gurion University Medical School in Israel. Clinical performance assessment of the first-year course in emergency medicine and trauma was done using a practical examination (PE). In the continuous process of critically reviewing the course objectives and assessment methods the objective structured clinical examination (OSCE) was chosen, for the first time in our medical school, as a tool for course development as well as evaluation of the existing PE. Seven experimental OSCE stations were designed which covered some of the course and practical examination topics. Twenty-six first-year medical students have taken both examinations concurrently. Twenty-three students answered an attitude questionnaire regarding both examinations. Results have indicated that the OSCE provided additional and crucial information on students' deficiencies in clinical performance which were not available from the PE. Those differences were probably due to realistic OSCE station content, highly simulated set-ups, and the objectivity of the examiner, all of which have contributed to a more challenging examination, as compared to the PE. The OSCE in emergency medicine and trauma seemed to have a relatively high level of acceptance by both staff and students. In our opinion it seems that the OSCE is a better tool for first-year level final assessment in emergency medicine and trauma. is a better tool for first-year level final assessment

Clinical Competence↗
PubMed1991

The effect of growth hormone on weight gain and pulmonary function in patients with chronic obstructive lung disease.

Thirty to 60 percent of patients with chronic obstructive pulmonary disease (COPD) are malnourished, and this affects ventilatory muscle function and prognosis for survival adversely. We studied the effect of growth hormone (GH) in malnourished patients with COPD (n = 7, mean FEV1 of 1.1 +/- 0.2 L, 45 +/- 7 percent of predicted values; less than 90 percent of ideal body weight). The subjects received a balanced diet of 35 kcal/kg with 1 g of protein/kg for 1 week (pre-GH). During the following three weeks, they received the same diet plus subcutaneous injections of recombinant methionyl human GH (0.05 mg/kg daily). The subjects had no significant weight gain during the week of diet alone (0.07 +/- 0.11 kg, p = NS) but they had substantial weight gain during the first week of GH treatment (1.37 +/- 0.23 kg, p less than 0.01). Nitrogen balance also improved during GH treatment (+1.6 +/- 0.7 g/day on diet alone vs +3.8 +/- 0.5 g/day on diet plus GH, p less than 0.02). Maximal inspiratory pressure improved by 27 +/- 8 percent after GH treatment (p less than 0.02). No significant adverse effects occurred. Further study of the potential usefulness of GH in COPD utilizing a placebo-controlled trial is warranted.

Aged↗
PubMed1991

The use of sustained release delivery of chlorhexidine for the maintenance of periodontal pockets: 2-year clinical trial.

The release of chlorhexidine from an ethyl cellulose-based dosage form (SRD) has been shown to be effective in the reduction of the flora associated with periodontal pockets as well as in reducing probing depths. In this study, treatment with this dosage form was compared to routine maintenance therapy (RMT) in a 2-year, split mouth clinical trial. Ten patients with 84 pockets greater than or equal to 5 mm who had not received any periodontal therapy or systemic antibiotics over the last 6 months were included. The patients all received a full mouth scaling and root planing together with through oral hygiene instruction. Two months later (baseline) plaque index (P1I), bleeding on probing (BOP), pocket probing depth (PD), and attachment levels (AL) were assessed at all selected sites. Pockets on the control side then received RMT while the experimental pockets were treated with the SRD only. Treatment was repeated every 3 months for 2 years. The SRD treatment resulted in an improvement of greater than or equal to 3 mm in PD of at least 1 pocket in 8 of 10 patients, while RMT resulted in a similar improvement in only 1 of 10 patients (P = 0.012). Similarly a gain of attachment of greater than or equal to 3 mm was found in at least 1 SRD pocket in 8 of 10 patients. The RMT resulted in a similar improvement in only 2 patients (P = 0.012).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Changes in mode of control and self-control for post myocardial infarction patients evidencing Type A behavior: the effects of a cognitive/behavioral intervention and/or cardiac counseling.

A control model of psychological health was utilized to assess the effects of a cognitive/behavioral intervention and/or cardiac counseling with post myocardial infarction patients evidencing Type A behavior. A previously developed four quadrant control inventory measuring perceived mode of control and perceived self-control was given to groups in two sections of the Recurrent Coronary Prevention Project. The experimental group (coronary counseling plus cognitive/behavioral intervention) was tested after one year (E1) and two years (E2) of treatment. The cardiac counseling group was assessed only after two years (C2). As hypothesized, the cognitive/behavioral treatment section at E2 had a significantly higher overall satisfaction level and congruence between real and ideal self on each of the four quadrants than at E1, and than the cardiac counseling only (C2). Further, on each of the four quadrants, E2 had a psychologically healthier mode of control profile than the cardiac counseling only (C2); and a healthier profile on both the positive assertive and positive yielding mode of control than at E1. Finally, E2's self-control score was significantly higher than C2's. Comments on future directions in measuring perceived control, and on the relationship of control and Type A behavior are offered.

Cognitive Behavioral Therapy↗
PubMed1991

Structural and microbiological evaluation of a degradable sustained-release device for use in periodontal therapy.

Degradable protein matrices containing chlorhexidine were tested as intra-pocket drug delivery systems in the treatment of periodontal diseases. The properties of the device were mainly dependent upon the degree of cross linking in the matrix, which could be varied according to the preparative conditions. The degree of cross linking was determined by amino acid analysis based on the amount of free lysine in the protein. The release of chlorhexidine and of the plasticizer used in the preparation of the matrix were determined. The release of chlorhexidine from the matrix was prolonged for a period of 300 hours, and the release of plasticizer ceased after four hours. Limited clinical trials suggest that one of the degradable devices--that containing the highest amount of cross-linking--causes a significant reduction in the amount of perio-pathogenic bacteria following its insertion into the periodontal pockets of patients with periodontal disease.

Adult↗
PubMed1990

Histotoxicity of cyanoacrylate tissue adhesives. A comparative study.

Cyanoacrylate derivatives have been used as surgical adhesives for many years. Shorter-chain derivatives (methyl- and ethyl-cyanoacrylate) have proved to be histotoxic. Longer-chain derivatives (butyl- and isobutyl-cyanoacrylate) are much less histotoxic. Many surgeons continue to use ethyl-2-cyanoacrylate (Krazy Glue) despite the availability of a less toxic derivative, butyl-2-cyanoacrylate (Histoacryl). In this study, the histotoxicity and bone graft-cartilage binding ability of Krazy Glue and Histoacryl were compared. Bone grafts harvested from the anterior wall of the maxillary sinus were placed in a subcutaneous pocket and glued to auricular cartilage in the rabbit. Krazy Glue and Histoacryl were used in opposite ears, harvesting specimens at 1, 2, 4, 12, 24, and 48 weeks. The Krazy Glue-treated ears developed seromas with histologic evidence of acute inflammation, tissue necrosis, and chronic foreign body giant cell reaction. The Histoacryl-treated ears showed mild acute inflammation and mild foreign body giant cell reaction. The Krazy Glue was completely degraded within 12 months, while some Histoacryl was still present at 1 year. Histoacryl had minimal histotoxic effect and good bone graft-cartilage binding ability, whereas Krazy Glue demonstrated severe histotoxicity.

Animals↗
PubMed1990

Pulmonary function following positive pressure ventilation initiated immediately after birth in infants with respiratory distress syndrome.

Cardiopulmonary function following positive pressure ventilation, initiated immediately after birth, was evaluated in 10 very low birthweight infants with respiratory distress syndrome (RDS; RDS infants). Multiple gas rebreathing methodology was used to measure functional residual capacity (FRC), diffusing capacity of the lung for carbon monoxide (DLCO) and effective pulmonary capillary blood flow (Qeff) at 2, 24, and 72 hr of age. Cardiopulmonary function variables were also measured at 2 hr of age in 10 infants of similar birthweight who did not have RDS (non-RDS infants). In RDS infants, mean FRC at both 2 hr of age (15 mL/kg or 0.42 mL/cm) and 24 hours of age (20 mL/kg or 0.54 mL/cm) was less than published predicted values for healthy infants and significantly less than values in non-RDS infants at 2 hours of age (29 mL/kg or 0.8 mL/cm). By 72 hr of age, mean FRC in RDS infants rose to predicted. At 2 and 24 hours of age, mean Qeff in RDS infants (41 and 38 mL/min/kg, respectively) was below predicted, as well as below the value observed in non-RDS infants at 2 hr of age (62 mL/min/kg). in RDS infants. DLCO remained well below published predicted values throughout the first three days of life. We conclude that early aggressive respiratory therapy does not result in the establishment of normal lung volumes during the first day of life, but it does so by 3 days of age. However, in spite of intubation immediately after birth and the application of continuous positive pressure ventilation during the first 3 days of life, very low birthweight infants with RDS continue to have significant alteration in lung function, evidenced by impaired diffusing capacity of the lung and low arterial-alveolar oxygen tension ratios.

Functional Residual Capacity↗
PubMed1990

The effects of low levels of dietary toxic weed seeds (jimson weed, Datura stramonium and sicklepod, Cassia obtusifolia) on the relative size of rat liver and levels and function of cytochrome P-450.

Preliminary studies and previous work by other investigators have shown that jimsonweed and sicklepod seeds are very toxic. Such seeds and others are co-harvested and are often found mingling with commercial grain destined for human consumption. Low levels of these seeds were studied here to determine whether such levels would show signs of intoxication in rats by modulating growth, liver weight and relative size, cytochrome P-450 levels and function, and other relevant parameters proven to be sensitive to low levels of toxicants. Assessment of these factors showed that jimson weed does give indications of intoxication at low levels, whereas the highly toxic sicklepod does not give discernible indications.

Administration, Oral↗
PubMed1990

Tuberculous cold abscess of the corpus cavernosum: a case report.

A rare case of tuberculous cold abscess of the corpus cavernosum is presented. The only presenting symptom was obstructive urinary symptoms caused by external compression of the urethra by the abscess. Diagnosis was reached after surgical drainage and specific antituberculosis therapy led to a satisfactory conclusion.

Abscess↗
PubMed1990

Preventability of malpractice claims in emergency medicine: a closed claims study.

We conducted a retrospective study of 262 malpractice claims against emergency physicians insured in Massachusetts by the state-mandated insurance carrier; these 262 claims were closed in the years 1980 through 1987. A total of $11,800,156 in indemnity and expenses was spent for these 262 claims. In 211 cases, the allegation was failure to diagnose a medical or surgical problem. One hundred eighty-four of these cases were included in the following eight diagnostic categories: chest pain, abdominal pain, wounds, fractures, pediatric fever/meningitis, aortic aneurysm, central nervous system bleeding, and epiglottitis. These eight categories accounted for 66.44% of the total dollars spent for the 262 claims. Because of the high incidence and dollar losses attached to these eight diagnostic categories, the Massachusetts Chapter of the American College of Emergency Physicians (MACEP) has developed clinical guidelines for the evaluation of these high-risk areas. Of the 184 high-risk claims, 99 claim files were reviewed; 45 of these reviewed claims were judged by physician reviewers as preventable by the application of the MACEP high risk clinical guidelines. From 22.26% to 46.4% of the $11,800,156 spent on the 262 claims could have been saved by the application of the MACEP clinical guidelines.

Chest Pain↗