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Biomedical subjects

C Cohen

Publications and source records attributed to C Cohen.

At least 361 records · Page 20Linked to original sources
PubMed1982

Genetic control of C6 polymorphism and C6 deficiency in rabbits.

The genetic control of the sixth component of complement (C6) in rabbits has been studied by quantitation of C6 functional and antigenic levels and identification of polymorphism by isoelectric focusing (IEF) in gels. Patterns of inheritance of C6 variants in families carrying a silent gene for C6 were examined, and it was found that 3 common plasma phenotypic variants, C6 A, C6 B, and C6 QO were under the genetic control of allelic genes, C6*A, C6*B, and C6*QO. In IEF patterns, C6 A could be identified by its isoelectric point that was slightly more acidic than that of C6 B. C6 QO was undetectable because it lacked functional and antigenic activity. The C6*A/C6*B genotype displayed a mixed IEF pattern with bands characteristic of both C6 A and C6 B. Functional and antigenic levels of C6 that were found in heterozygous C6*A/C6*QO and C6*B/C6*QO rabbits were approximately one-half of the C6 levels found in the corresponding homozygous animals. The phenotypic variation closely resembles that previously observed in humans and rhesus monkeys, as well as preliminary data in rabbits. The patterns of inheritance indicated that the two common C6 structural genes and the deficiency gene were allelic variants at the same genetic locus.

Animals↗
PubMed1982

Immunohistochemical acid phosphatase level and tumor grade in prostatic carcinoma.

An immunoperoxidase technique to detect prostatic-specific acid phosphatase (PSAP) was used on specimens from 98 cases of prostatic carcinoma that were graded by both the Gleason and the Mostofi systems, to see if tumor grade correlated with amount of PSAP seen in tissue. Most tumors showed strong, diffuse cytoplasmic staining; no significant difference was seen among the various grades. Other than focal, weak staining of renal tubular epithelium, the antibody to PSAP gave uniformly negative results with a variety of normal and neoplastic tissues. In light of the great sensitivity and specificity of this technique, it potential applications include diagnosis of poorly differentiated prostatic malignant neoplasms, whether primary or metastatic.

Acid Phosphatase↗
PubMed1982

Nasal polyposis--a multidisciplinary study.

Thirty-seven adults with nasal polyps were assessed in a multidisciplinary fashion. It was found that 43% of patients were allergic and 57% had asthma. Performing a polypectomy did not alter lower airway flow rates. Eosinophilia was prominent in nasal secretions of both atopics and nonatopics. Histological characteristics could not distinguish the "allergic" from the "inflammatory" polyp. Immunofluorescent studies indicated an abundance of polyp IgE leading to speculation of an IgE mediated process in polyp formation.

Adult↗
PubMed1982

On the quality of life: some philosophical reflections.

Quality of life, as a concept pertaining to patients undergoing coronary artery bypass graft surgery, is explored. A theory of life quality, based on the capacity of the patient to realize his own life plans, is proposed, explaining the role of differing factors, general and individualized. Using the proposed theory, three avenues of investigation are suggested, each aimed at the more effective use of surgery in improving life quality.

Coronary Artery Bypass↗
PubMed1981

Induction of lymphoid cell chimerism in noninbred, histocompatible rabbits. A new model for studying allotype suppression in the rabbit.

Noninbred rabbits, matched with regard to the major histocompatibility complex (RLA-A and RLA-D loci) but mismatched for Ig allotypes, served as donors (adult) and recipients (newborn) of lymphoid cells. Lasting chimerism regularly followed the transfer of 1 x 10(8)-3 x 10(8) spleen, lymph node, or bone marrow cells, as indicated by the continued production of Ig with allotypic determinants of both donor and recipient. Typically, Ig of donor allotype accounted for 25-50% of total allotypic Ig at 4 wk of age and the amount of donor Ig produced remained stable for up to 20 mo. Total allotypic Ig levels remained normal in the chimeric rabbits. "Chimeric drift" or a gradual diminution of donor products over a period of several months, occurred in some individuals. Transfer of lymphoid cells from allotype-suppressed adult donors to newborns of appropriate allotypes did not result in specific suppression of the target allotype in the recipients. Other experiments showed that lymphoid cells from suppressed donors adoptively transferred to histocompatible recipients continued to synthesize Ig of the nonsuppressed type only. The suitability of using an outbred population of histocompatible but allotype-mismatched rabbits for analyzing allotype suppression and other immunoregulatory phenomena is demonstrated by the results presented here.

Animals↗
PubMed1981

Obstructive jaundice in pancreatitis.

Twelve patients with obstructive jaundice as a direct result of pancreatitis or its complications are described. The value of ultrasonography in the diagnosis of this condition is stressed. The criteria for surgical intervention and the operation of choice are discussed.

Adult↗
PubMed1981

[Cardiovascular risk factors in headquarters staff of the World Health Organization].

Analysis of 2333 medical files of the World Health Organization's headquarters staff in Geneva gives insight into the epidemiology of cardiovascular risk factors in nationals originating from 67 different countries but living in the same environment. The study confirms well established facts such as the prevalence of hypertension (HT) with respect to sex, age, and period of observation, its consequences and interrelation with high cholesterol levels, diabetes, and obesity. The importance of a medical service with emphasis on prevention is stressed. Major differences in relation to geographic origin are noted for men. The highest percentage of HT (32%) is noted for staff members from Germanic countries. There is a concentric decrease according to nationality: 29 to 25% for the other countries of Central, Western, and Southern Europe, 23 to 18% for the USSR, Arab countries and North America, 9 to 6% for South East and Eastern Asia and African countries south of the Sahara (p less than 0.05 between the extremes). India and Australia do not fit the pattern of concentric decrease, since a high percentage of men in those countries have HT. As the number of files available was insufficient to carry out the same analysis for women or to determine other factors of cardiovascular risk, the study will be extended to cover the staff of other International Organizations in Geneva.

Age Factors↗
PubMed1981

The pathophysiology of inspiratory muscle fatigue.

The critical value of the rate of energy consumption of the inspiratory muscles above which fatigue occurs appears in some instances to be predictable from the relationship between energy demands and energy supplies rather than from the percentage of fatigue-resistant fibres in the inspiratory muscles. When this is the case the critical value of the external power produced by the inspiratory muscles is given by the product of muscular efficiency and the rate at which energy is supplied. Efficiency is reduced by hyperinflation and recruitment of the intercostal and accessory muscles of inspiration. The rate at which energy is supplied is decreased in states characterized by low cardiac output. The condition of low cardiac output, combined with the high oxygen cost of breathing against fatiguing loads, may be lethal in cardiogenic shock. Although the immediate cause of fatigue may not be related to reduced energy supplies, clinically useful predictions of conditions predisposing to fatigue result from an understanding of factors determining the balance between the energy demands and supplies of the inspiratory muscles. These predictions aid in the diagnosis of inspiratory muscle fatigue and have important therapeutic implications.

Animals↗
PubMed1981

Behavioral correlates of physical and neuromotor maturity in adolescents from different environments.

The relationship between neuropsychological performance (sequencing and visuospatial processing) and neuromotor and physical maturity was investigated among ninety 14- and 15-year-old boys selected from 3 socioeconomic backgrounds: upper middle class, white collar, and blue collar. Sequencing was measured by the Stroop Word and Color Test and by stability of rhythmic finger tapping; visuospatial processing was measured by a locomotor mazes task. We had predicted that rate of maturation would be correlated positively with sequencing and negatively with visuospatial performance independent of socioeconomic background. The correlations between neuropsychological performance and maturational status were in the directions predicted, but the appearance of these relationships was not independent of socioeconomic status. In the upper middle class group, visuospatial processing was negatively related to physical maturity; in the white collar group, motor sequencing was positively related to physical maturity; and in the blue collar group, all the sequencing measures were positively related to neuromotor maturity.

Adolescent↗
PubMed1981

The role of computerized tomography in renal transplant patients.

We evaluated 53 patients with computerized tomography after renal transplantation. The diagnostic value of computerized tomography scanning was primarily in differentiating between patients with acute rejection and those with obstructive uropathy, urinary fistula or significant perinephric fluid collections. Computerized tomography guidance also may be helpful in performing anterograde pyelography or percutaneous allograft biopsy. The computerized tomography scan provides an effective, non-invasive, complementary method of evaluating post-transplant dysfunction.

Graft Rejection↗
PubMed1981

Streptococcal M protein: alpha-helical coiled-coil structure and arrangement on the cell surface.

The conformation and molecular dimensions of purified type 6 streptococcal M proteins establish the close structural relationship of these molecules to tropomyosin. Ultracentrifuge studies reveal that the M molecules exist as stable dimers; circular dichroism spectra indicate that the molecules contain about 70% alpha helix; and fiber x-ray diffraction diagrams show the characteristic reflections of the alpha-helical pattern. Electron microscopic images of M protein shadowed with platinum reveal rod-shaped molecules having the same width as tropomyosin. However, the lengths of the M molecules are about 30% shorter than lengths predicted by assuming a completely alpha-helical molecule. These findings indicate that the structure of the M6 protein is primarily alpha-helical coiled coil. Comparison of the lengths of the fibers on the surface of the streptococcus and the isolated M proteins suggests that each fiber on the cell wall consists of a single M-protein molecule approximately 500 A long. The structure determined for these fimbriae is the first alpha-helical coiled-coil conformation to be demonstrated for bacterial surface projections.

Antibodies, Bacterial↗
PubMed1981

Spikes and fimbriae: alpha-helical proteins form surface projections on microorganisms.

Two basic alpha-helical plans appear to characterize portions of the proteins projecting from the surface of many microorganisms. Structure A is related to that of the antibody-binding protein A of Staphylococcus aureus, in which a single polypeptide chain doubles back to form an Anti-parallel domain; the other, structure M, is related to the M proteins of group A streptococci, in which Multiple parallel alpha-helical chains interlock in a coiled-coil conformation. A projection about 100 A long may be organized on either plan, but very long projections are likely to be of the M pattern. The alpha-helical motif may account for the length of these spikes, with other functions such as anchoring or antiphagocytic activity located in domains of different structure.

Bacterial Proteins↗