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Biomedical subjects

A Ulmer

Publications and source records attributed to A Ulmer.

14 recordsLinked to original sources
PubMed1992

Season of birth of schizophrenics in Mississippi, USA.

Prior reviews indicate that schizophrenics tend to be born in the winter, relative to non-psychiatric controls. This conclusion has been criticized, however, as the association between birth seasonality and schizophrenia may be the result of a statistical artifact, the age-incidence effect. To examine this possibility, we studied the birth seasonality of 2892 schizophrenics, controlling for the age-incidence effect. Both before and after instituting these controls, we found excesses for the months of December and March. We conclude that the age-incidence hypothesis does not provide any general explanation of the season-of-birth effect in schizophrenia.

Adolescent↗
PubMed1991

Differences between schizophrenics born in winter and summer.

A total of 1814 patients were studied from the Mississippi State Hospital with a DSM-III diagnosis of schizophrenia and aged 15-39 years at the time of admission. The 634 schizophrenics with a birth date between 1 December and 31 March were compared with the 1180 born between 1 April and 30 November for age of admission, race, sex, marital status, duration of initial admission and clinical subtype. The only significant difference between the variables was the duration of the first admission: winter-born patients had a shorter psychiatric hospitalization than summer-born schizophrenics. These findings are discussed in accord with similar studies.

Adolescent↗
PubMed1985

Prospective evaluation of chymopapain sensitivity in patients undergoing chemonucleolysis.

Immediate anaphylactic reactions after intradiscal chymopapain (CP) injection may occur in 1% of patients undergoing chemonucleolysis (CN). Skin prick testing to CP (10 mg/ml), a prescreening history, and CP serum-specific IgE determinations by the RAST method were performed in order to identify patients presensitized to CP before CN. Follow-up repeat CP skin testing and serum-specific IgE were done 2 to 6 weeks after CN to detect CP IgE-mediated sensitization resulting from the injection. Three of 84 patients who exhibited positive skin tests to CP before CN did not receive CP injections. Only one of the three patients (33%) was detected with elevated CP serum-specific IgE before CN. No immediate severe anaphylactic reactions caused by CP injection were encountered in the remaining 81 patients with negative CP skin tests and RASTs before CN. Eight (10%) nonlife-threatening immediate and late reactions were associated with conversion from negative skin tests and RASTs before CN to positive skin tests or RASTs after CN. Overall, 19 of 52 (37%) patients who returned for follow-up testing developed cutaneous sensitization to CP after CN. Despite the fact that RAST values after CN in these patients were significantly higher (p less than 0.002) than those with negative skin tests after CN, the sensitivity of the RAST was only 72% for identifying patients who developed positive CP skin tests after CN. This study demonstrated that CP skin testing is essential for prescreening patients because it was more sensitive than RAST for identification of CP sensitivity both before and after CN. Late allergic reactions and cutaneous sensitization to CP were common sequelae of CN.

Anaphylaxis↗
PubMed1978

The formation of B-lymphocyte colonies in agar contained in glass capillaries.

Optimal conditions were established for a micro method for the production of colonies of B lymphocytes from mouse spleen cells cultured in agar in glass capillaries, in the presence of bacterial lipopolysaccharide (LPS). Besides LPS the cultures require 5 X 10(-5) M mercaptoethanol and 20% horse serum for optimal colony growth. Foetal calf serum and heat-inactivated horse or foetal calf serum were found to be inferior. An agar gel strength of 0.3% was best for colony counting. A sigmoid curve was obtained when the number of colonies formed was related to the seeded cell density suggesting that some kind of cell to cell co-operation is essential for colony formation. The daily kinetics of colony growth were followed by microscopic colony counting and photometric capillary scanning with integration of the signal areas. Both methods indicated that colony growth had ceased by day 6. The combination of both methods gave the most realistic picture of B-lymphocyte colony development.

Agar↗
PubMed1976

Differences between lymphoid cell populations of guinea pigs and mice as determined by the response to mitogens in vitro.

The stimulation of guinea pig lymphocytes by phytohemagglutinin (PHA), concanavalin A (ConA), methanol-extracted residues of tubercle bacilli (MER), purified protein derivative of tubercle bacilli (PPD), dextran sulphate (DS) and E. coli lipopolysaccharide (LPS), was determined and compared with that of mouse lymphoid cells. The sources of lymphocytes tested were spleen, thymus, lymph nodes and bone marrow. The degree of activation of DNA synthesis by PHA and ConA was higher in guinea pig thymocytes and lymph node cells than in corresponding sources of mouse lymphocytes. The optimum degree of stimulation by PHA and ConA was approximately the same in guinea pig thymocytes, while ConA was by far a better stimulator than PHA for mouse thymocytes. All four B-cell mitogens tested (MER, DS, PPD and LPS) activated DNA synthesis in mouse lymphoid cells while only MER and DS were effective in guinea pig lymphocytes. A guinea pig spleen cell population depleted from B cells was not stimulated, neither by DS nor by MER, while it still responded to PHA and ConA. These results indicate that the proliferative response due to MER and DS occurs in the B-cell compartment. It is suggested that the differences between guinea pigs and mice with respect to their ability to develop a cell-mediated type immunity and to respond to T-independent antigens are related to differences in the relative proportions and degrees of maturation of T- and B-cell subpopulations, as reflected by the selective responsiveness to various mitogens.

Animals↗
PubMed1976

Two distinct lumphocyte-stimulating soluble factors (LAF) released from murine peritoneal cells. I. The cellular source and the effect of cGMP on their release.

Culture fluids of murine peritoneal cells contain two distinct, non-dialysable priniciples (LAF) with thymocyte proliferation-stimulating properties. One of them is elaborated from phagocytic cells (presumably macrophages), the other is released by non-phagocytic cells (lymphocytes). cGMP added exogenously stimulates the production and/or release of LAF from phagocytic cells, but not from non-phagocytic cells. The phagocytic cells (but not the lymphocytes) require intact RNA and protein synthesis for LAF release. The action of LAF differs from those of cGMP itself by being non-dialysable, and unable to prevent the inhibitory action of cAMP on mitogen-stimulated lymphocyte proliferation.

Animals↗
PubMed1975

Effect of cyclic nucleotides on DNA synthesis in mouse lymphoid cells.

The effect of eight cyclic purine and cyclic pyrimidine nucleotides on DNA synthesis on mouse lymphoid cells was investigated. Two out of eight compounds tested, namely 2', 3'-cyclic guanosine monophosphate (2', 3'-cGMP) as well as 3', 5'-cyclic guanosine monophosphate (3', 5'-cGMP), stimulate thymidine incorporation in all types of lymphocytes tested. The stimulatory activity of the cyclic guanosine nucleotides as well as the effects of lectins could be antagonized by 3', 5'-cyclic adenosine monophosphate (3', 5'-cAMP). 2', 3'-cGMP seems to stimulate preferentially mature T-cells while 3', 5'-cGMP preferentially acts on B-cells.

Animals↗
PubMed1975

The control of immune response in vitro by Ca2+. II. The Ca2+-dependent period during mitogenic stimulation.

The Ca2+ requirement for stimulation of DNA synthesis in vitro by phytohaemagglutinin (PHA) and by lipopolysaccharide (LPS) was investigated using mouse spleen cells. During mitogenic stimulation two periods could be distinguished: a Ca2+-independent period which was followed by a Ca2+-dependent period. The results suggest that Ca2+ is required for a step preceeding DNA synthesis but not for the early initial phase of transformation.

Animals↗
PubMed1975

The antagonistic action of cyclic GMP and cyclic AMP on proliferation of B and T lymphocytes.

The effect of c-AMP, c-GMP and both substances together on (3H)-thymidine incorporation into nuclear DNA was investigated using spleen cells of normal and athymic nude mice. c-GMP induces DNA synthesis in both normal and nude spleen cell populations. c-AMP inhibited the stimulatory activity of c-GMP as well as the phytohaemagglutinin (PHA) and lipopolysaccharide (LPS) response of spleen cells. The inhibitory activity of c-AMP on the PHA and LPS responses can be reversed by c-GMP. The possible role of cyclic nucleotides in the regulation of cell proliferation and of the immune response is discussed.

Animals↗