Biomedical subjects
Publications and source records attributed to D Lehmann.
Tertiary derivatives of the beta-receptorblocker propranolol were synthesized and pharmacologically tested for anticonvulsive activities. The results show that it is possible, to separate the beta-receptor blocking from the anticonvulsive activities by modifying the chemical structure.
Changes of the event-related potential (ERP) map landscape with time and condition were used to identify qualitative changes in the ERP generating process which are indicative of a change in the functional microstate. Twelve subjects attended or ignored unilaterally presented visual stimuli with and without subjective contours. ERP map series from 16 electrodes were adaptively segmented to identify periods of stable map landscape, using topographic descriptions (map maxima and minima). Attention as well as the subjective contours changed the map topography and increased the map amplitude. From 170 to 380 msec, they had similar effects on the antero-posterior map topography. Topographic differences between the effects of attention and subjective contours were also present, but affected mainly the left-right topography. The results are in line with the notion of attentional involvement in subjective contour perception and show that global modulation of exogenous brain activity cannot account for topographic changes with attention or with subjective contours. They further establish space-oriented data reduction as a powerful tool to identify components and to distinguish among hypotheses about the underlying generator processes.
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This study examined the clinical signs and symptoms in 897 children aged under 5 years presenting with pneumonia to Goroka Hospital in the highlands of Papua New Guinea between June 1982 and July 1985. The usefulness of the signs in predicting severity of disease was determined and risk factors for severe disease were identified. While cyanosis and poor feeding were the strongest predictors of death, bronchial breathing, grunting, and nasal flaring also significantly increased the risk of dying. First-born children, children under 1 year of age, females, malnourished children, and children with symptoms for more than 7 days were at increased risk of severe disease and of dying. Fever alone did not increase the risk of dying unless it was present for more than 7 days. These clinical signs of severity and risk factors may be used to improve the efficiency of health education programmes, for both health workers and mothers, aimed at reducing childhood mortality from pneumonia.
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Testing of a modified Toxoplasma immunosorbent adsorption assay (IgM-ISAGA) for proving of Toxoplasma specific IgM antibodies. The IgM-ISAGA was assessed for the possibility of its application as a routine method in the serodiagnosis of toxoplasmosis and was compared with the IgM-IFT. On examination for specific on 136 sera, no false-positive results were obtained in the IgM-ISAGA in contrast to 5 false-positives in the IgM-IFT, due to the presence of rheumatoid factor. Its sensitivity was tested on 162 sera. The IgM-ISAGA reacted positive in 89 cases, the IgM-IFT in only 51. It was concluded that the IgM-ISAGA is a simple, sensitive and highly specific test applicable in smaller laboratories as a confirmatory reaction in the control of toxoplasmosis during pregnancy and in confirmation of connatal toxoplasmosis.
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The effect of sex hormones on human lymphocytes was examined in vitro on cell cultures of human peripheral blood mononuclear cells (HPBM). Cells were stimulated using T- and B-cell mitogens, and hormones in physiological (nM) or pharmacological (microM) concentrations were added. Proliferation was determined by measuring the incorporation of tritiated thymidine. It was found that both testosterone and dihydrotestosterone, in physiological concentrations, can attenuate DNA synthesis. The effect was dose dependent in that pharmacological concentrations of both testosterone and dihydrotestosterone caused a strong inhibitory effect on proliferation of in vitro cultured HPBM. However, cell cultures of a few individuals were insensitive to the androgens even at pharmacological concentrations. Also, no difference could be detected in the response between cultured cells of females and males. Although a slight reduction in antibody production was evident in pokeweed mitogen-stimulated cultures, in the presence of both testosterone and dihydrotestosterone, it was, however, not statistically significant.
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The spontaneous EEG, viewed as a series of momentary scalp field maps, shows stable map configurations (of periodically reversed polarity) for varying durations, and discontinuous changes of the configurations. For adaptive segmentation of map series into spatially stationary epochs, the maps at the times of maximal map relief are selected and spatially described by the two locations of maximal and minimal (extreme) potentials; a segment ends if over time an extreme leaves its pre-set spatial window. Over 6 subjects, the resting alpha EEG showed 210 msec mean segment duration; segments longer than 323 msec covered 50% of the total time; the most prominent segment class (1.5% of all classes) covered 20% of total time (prominence varied strongly over classes; not all possible classes occurred). Spectral power and phase of averages of adaptive and pre-determined segments demonstrated the adequacy of the strategy, and the homogeneity of adaptive segment classes by their reduced within-class variance. It is suggested that different segment classes manifest different brain functional states exerting different effects on information processing. The spatially stationary segments might be basic building blocks of brain information processing, possibly operationalizing consciousness time and offering a common phenomenology for spontaneous activity and event-related potentials. The functional significance of segments might be modes or steps of information processing or performance, tested, e.g., as reaction time.
Immune response in a patient with an in-situ seminoma of the testis was studied. Immunohistochemical examination of the testicular biopsy demonstrated remarkable intracellular and membraneous accumulation of IgG antibodies in the atypical spermatogonia. Using FITC-conjugated Concanavalin A, an abnormally high binding of Concanavalin A was detected in the transformed cells. Circulating antibodies directed against an antigenic determinant (60 kD) which is expressed on normal human spermatozoa and lymphocytes were found only in the patient's serum and not in 500 control sera. The role and possible diagnostic value of this autoimmune reactivity in testicular malignancies are discussed.
The validity of commercial latex agglutination kits for detection of Haemophilus influenzae type b and Streptococcus pneumoniae antigens in serum and urine specimens was studied. We tested serum and urine specimens from 44 patients with bacteremic pneumonia (23 S. pneumoniae, 13 H. influenzae type b, 11 other) with commercial latex agglutination kits (Directigen, Bactigen) for S. pneumoniae and H. influenzae type b antigens. All specimen samples were randomized and read blindly by two readers. Interreader reproducibility was 100%. The sensitivity and specificity of both kits for H. influenzae type b antigens in serum and urine were greater than 90%. None of the 24 urine samples from S. pneumoniae bacteremic patients were positive by either kit, although 6 ng of type 3 polysaccharide could be detected in spiked urine. Sensitivity for S. pneumoniae antigens in serum was 27% for Directigen and 38% for Bactigen. Specificity for S. pneumoniae antigens in serum was 95% for Directigen and 74% for Bactigen. The results suggest that the kits are useful in diagnosing H. influenzae type b pneumonia. However, the commercially available S. pneumoniae reagents tested appear to have limited utility for diagnosing S. pneumoniae pneumonia because both kits lack sensitivity and Bactigen lacks specificity, as well.
Immunological deposits in the testis and circulating antibodies to spermatozoa are presented as a possible explanation for infertility in man. Testicular biopsy specimens from infertile patients (N = 52) as well as from fertile controls (N = 6) were analyzed immunohistochemically by using semithin sections. Immunoglobulin deposits were found in the testes of 21 patients. Antibody deposits were observed on the seminiferous tubule wall, on germ cells or in the interstitium. In two cases, the C3 complement component was detected on the tubular wall and in one case on atypical spermatogonia. Deposits of immunoglobulin class G were found most frequently, and were often attached to the seminiferous tubule wall. In addition, the occurrence of circulating antisperm antibodies in the sera of these patients was examined by a recently developed method, the immunobeads binding test. A significant number of patients with normal spermatogenesis had antibodies that exhibited a strong binding reaction to spermatozoa as observed by the immunobeads binding test. It is suggested that at least two different immunological mechanisms may be involved in pathological infertility: an immunoglobulin deposit, induced locally in the testis, in a manner specifically against the germ cells and the seminiferous tubular basement membrane, or in a manner nonspecifically against seminiferous tubular wall, and asystemically induced immunoglobulin production which is directed against spermatozoal antigens.
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Routine examination of a testis biopsy from a patient with oligospermia and a large varicocele in his left testicle and who was childless for over 2 years showed carcinoma in situ (CIS) with atypic spermatogonia in his right testicle. Immunohistochemical investigations of this tissue revealed large intracellular deposits of immunoglobulin G (IgG) restricted to the atypical cells. By blot-immunobinding test of the patient's serum, circulating antibodies against a molecule with an approximate molecular weight of 60 kD were found. Such antibodies were not found in a total of over 500 infertile patients and fertile controls examined. This molecule was extracted from pooled normal human sperms by trypsin digestion and eluted out of a sodium dodecyl-sulphate polyacrylamide gel (SDS-PAGE). This elute is currently used for raising monoclonal antibodies. An analysis of the direct chromosome preparations from the testis biopsy showed both numerical and structural chromosomal aberrations. This might indicate that the atypical cells have already been transformed and hence could be considered as malignant.