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Biomedical subjects

A Michael

Publications and source records attributed to A Michael.

At least 109 records · Page 6Linked to original sources
PubMed1991

Productive interactions between B and natural killer cells.

In this report, we have established that natural killer (NK) cells can increase IgG2a secretion by B lymphocytes as well as alter the distribution of the remaining immunoglobulin isotypes. The effect of NK cells on B cell differentiation is similar to that obtained by the direct addition of recombinant interferon-gamma (IFN-gamma) and, therefore, most likely results from the elaboration of IFN-gamma by NK cells, this is a clear demonstration that NK cells can regulate cell function(s) via a mechanism other than cytotoxicity. In addition, we have shown that the induction of NK cells by B lymphocytes requires close interactions between the two cell types. Further, while only low-density B lymphocytes activated in vivo are effective inducers of NK cells, high-density, resting B cells can be rendered effective by preactivation with either interleukin-4 or anti-mu.

Animals↗
PubMed1990

Fertility prognosis for infertile men: results of follow-up study of semen analysis in infertile men from two different populations evaluated by the Cox regression model.

Using the Cox proportional hazard regression model on one material (group I = 765, 1950 to 1951) we have identified four variables of semen analysis with significant prognostic information about fertility. The four variables were combined into a model for establishing the probability of the individual male to achieve pregnancy as a function of time. This model is tested first on another material (group II = 321, 1977 to 1985). A Goodness-of-fit test indicates excellent agreement between the expectations from the model and the observed number of pregnancies in group II. Second, the two groups are pooled (= 1,086). Then only three variables give significant prognostic information about the time until pregnancy: (1) the man's age at semen analysis (years); (2) the percentage of morphologically normal spermatozoa (ln %); and (3) the degree of motility (good/poor). These three important variables enter into a new and better prognostic model.

Female↗
PubMed1990

Effect of gelatin infusions on blood serum lipid pattern.

The effect of gelatin infusions in rat on the various serum lipid constituents was studied by measuring the mean values of total lipids, lipoprotein lipase, triglycerides, phospholipids, cholesterol, non-esterified fatty acids, and lipoproteins. These measurements were made immediately following a single intravenous infusion of gelatin solution (1 ml/100 g body wt) and at different time intervals post-infusion. Repeated intravenous infusions of gelatin were also given to another group of rats and the above mentioned lipid constituents were measured 24 h after each dose. The results obtained showed that gelatin infusions have a definite hypolipemic effect. There was a significant reduction in the levels of total lipids, triglycerides, cholesterol, and B + preB/alpha ratios immediately following infusion and at 5, 24 and 48 h postinfusion. This reduction was transient and the values were gradually normalized at the end of the first week postinfusion. In rats receiving repeated i.v. infusions, the results obtained showed a significant decrease in the same lipid constituents during the whole month of gelatin administration. Values of lipoprotein lipase, lipid phosphorous and non-esterified fatty acids showed insignificant changes from baseline values at all time intervals following single and repeated i.v. infusions of gelatin solution.

Animals↗
PubMed1989

Cognate interactions between helper T cells and B cells. II. Dissection of cognate help by using a class II-restricted, antigen-specific, IL-2-dependent helper T cell clone.

In order to determine the involvement of T-B cell contact vs lymphokine production in mediating B cell cycle entry and progression, Th cell clones "defective" in lymphokine production were cloned. Th-3.1 is one such clone that required IL-2 to produce significant levels of IL-4 and IFN-gamma. Unlike conventional Th clones, Th-3.1 induced B cell proliferation only in the presence of Ag and IL-2. In contrast to the absolute requirement of IL-2 for Th-3.1-induced B cell proliferation, IL-2 was not required for the formation of stable Th-3.1-B cell conjugates or Th-3.1-induced B cell entry into the G1 phase of the cell cycle. In the absence of IL-2 and under conditions that promoted Th-B cell interactions, Th-3.1 induced 10 to 20% of resting B cells to enter G1. B cell entry into the cell cycle was not inhibited by anti-lymphokine mAb or promoted by exogenous lymphokines, suggesting that endogenous lymphokine activity was not required for Th-3.1-induced G0 to G1 transition. The data suggested that the IL-2-independent induction of B cells into G1 by Th-3.1 was a cell contact-dependent event. Direct proof that Th-3.1-B cell contact was necessary for B cell cycle entry was provided by comparative in situ analysis of the RNA synthetic activity and the RNA content of B cells that were in physical contact with Th-3.1 or not in contact with Th-3.1. In situ autoradiography of RNA synthesis illustrated that a high frequency of B cells in contact with Th-3.1 expressed heightened RNA synthetic activity, whereas "bystander" B cells were less frequently induced into cycle. In situ laser cytometry of B cell size and total RNA content showed that B cells in physical contact with Th-3.1 had a higher RNA content and were larger than "bystander" B cells present in the same microcultures. This model system has allowed the dissection of T cell help into IL-2-dependent and IL-2-independent phases. Early cell contact-dependent events and B cell cycle progression into G1 were IL-2 independent, whereas the production of lymphokines (IL-4, IFN-gamma) by Th-3.1 and Th-3.1-induced B cell proliferation was IL-2 dependent.

Animals↗
PubMed1989

Role of transcriptional termination in the regulation of mu mRNA expression in B lymphocytes.

The synthesis of mRNA for mu-chain of membrane vs secretory IgM in normal resting B lymphocytes is stringently regulated. Very minimal amounts of microseconds mRNA are produced until the cells are stimulated. We have found a strong correlation between the initiation of mu S mRNA production and an alteration in the site of termination of polymerases transcribing the mu-gene. Furthermore, since the abundance of mu S mRNA is dependent on the differentiation stage of the B lymphocyte, we examined subpopulations of cells at various stages of activation and found that along with increased initiation of polymerases at the mu-locus, termination is moved further upstream in more highly differentiated cells. Therefore regulation of mu S mRNA may require factor(s) that induce transcriptional termination and these may be related to the factor(s) that augment transcriptional initiation.

Animals↗
PubMed1989

Regulation of B lymphocytes by natural killer cells. Role of IFN-gamma.

Using a co-culture system of fractionated B cells and highly purified NK cells, we have demonstrated direct interactions between B lymphocytes and NK cells. B cells are able to stimulate the production of IFN-gamma by NK cells. This stimulatory ability is restricted to a subpopulation of large, presumably in vivo activated B lymphocytes. The secreted IFN-gamma in turn inhibits polyclonally induced B cell proliferation. Small resting B cells neither stimulate IFN-gamma production nor are they measurably affected by NK cells.

Animals↗
PubMed1989

Penicillin-resistant Streptococcus pneumoniae and other nasal bacteria among children in remote areas of the fringe highlands of Papua New Guinea.

The nasal bacteriology of children in two areas of the western Schrader Range was studied. One area, served by an aid post since 1976, was compared with the other, which received its first medical care in 1984. Significant differences in the amount of resistance to penicillin were found, but not in the direction expected. These anomalous findings are interpreted in light of the particular histories of the groups involved, suggesting the transmission of resistant strains through contact among children.

Adolescent↗
PubMed1988

Psychosomatic disorders in psychiatric patients in a developing country.

This study reports the prevalence of psychosomatic disorders in psychiatric patients in India. The psychosomatic disorders studied were hypertension, peptic ulcer, bronchial asthma, rheumatoid arthritis, ischaemic heart disease and chronic pain. 21.5% of psychiatric patients had psychosomatic illnesses. Fifty five cases had two psychosomatic illnesses. Chronic pain (14.4%) and hypertension (9.9%) were the commonest. Patients with psychosomatic disorders were significantly more often older in age, females, married and from an urban habitat. Neurotic illness was the commonest diagnosis in them. Psychosis was significantly and inversely associated with psychosomatic disorders. This report emphasises the need for as much attention on psychosomatic problems in developing countries as in affluent ones.

Adolescent↗
PubMed1988

Psychosomatic patients in a psychiatric clinic.

This study reports lifetime prevalence of certain "psychosomatic disorders" in psychiatric patients in India. The "psychosomatic disorders" studied were peptic ulcer, bronchial asthma, rheumatoid arthritis, ischemic heart disease and irritable bowel syndrome. One percent of psychiatric patients had these psychosomatic illnesses. Ten of the fifteen cases had two psychosomatic illnesses. Patients with psychosomatic disorders were significantly more often older in age (p = 0.003) and from an urban background (p = 0.05) as compared to other psychiatric patients. Depression was the commonest diagnosis, and was significantly (p = 0.01) more often diagnosed in the psychosomatic patients. Psychosis was not diagnosed in patients with psychosomatic disorders. This article emphasizes the need for identifying concomitant psychosomatic problems in psychiatric patients for their appropriate management.

Adolescent↗
PubMed1988

Extensive hemosiderin deposition in the medial meniscus of a knee. Its possible relationship to degenerative joint disease.

Hemosiderin deposition in the tissues of the musculoskeletal system is unusual, and deposition of these pigments in the menisci of the knee is extremely rare. Conditions that may predispose to these changes include rheumatoid arthritis, hemochromatosis, pigmented villonodular synovitis, hemophilia, and tuberculous arthritis. A 79-year-old woman developed extensive hemosiderin deposition in the medial meniscus of a knee. Hemosiderin within meniscal chondrocytes was associated with degenerative joint disease and suggested a cause and effect relationship.

Aged↗
PubMed1986

Hemorrhage in cavum septi pellucidi.

One case of hemorrhage in the cavum septi pellucidi (CSP) is presented. This unusual location of intracranial hemorrhage was demonstrated by cranial sonography in a premature neonate.

Cerebral Hemorrhage↗
PubMed1986

Chronic pain in a psychiatric clinic.

Prevalence rate of chronic pain in a psychiatric outpatient clinic has been evaluated in this study and characteristics of chronic pain patients have been compared with non-pain psychiatric patients. Chronic pain was reported by 14.37% of psychiatric patients. Of these, 43% had dysthymic disorder, 20% had anxiety states and 20% somatoform disorders. As compared to the control group, chronic pain patients belonged more often to the middle age group (p less than 0.05), were more frequently females (p less than 0.001), married (p less than 0.02) and from an urban habitat. There is a marked difference in the diagnostic breakdown between the two groups with a predominance of dysthymic and anxiety disorders in pain patients. Very few chronic pain patients had psychosis. Major depression was found in equal proportions in pain and non-pain patients. The study identifies variables which differentiate chronic pain patients from other psychiatric patients.

Adolescent↗
PubMed1986

Content relevance and content coverage in tests of grammatical ability.

Three widely used tests of grammatical ability were evaluated for content-oriented test construction using two procedures. First, a decision-making model was developed to assist in judging the content relevance and coverage of each test using information provided by respective test authors. Second, a comprehensive model of the grammatical domain was applied to individual items on the tests so that descriptions and comparisons of their content domains could be made. Both evaluations showed inadequate content relevance and coverage for all three tests. The content domains of these tests were found deficient when judged against an external standard as well as when examined according to their own content specifications. The influence of inadequate content relevance and coverage on assessment and remediation is discussed.

Humans↗