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Biomedical subjects

M A Gerber

Publications and source records attributed to M A Gerber.

At least 163 records · Page 9Linked to original sources
PubMed1986

Immunohistologic analysis of lymphoid cells by a rapid double staining method.

The development of monoclonal antibodies has allowed characterization of subpopulations of lymphoid cells and of their in situ distribution in tissues. The feasibility of simultaneous localization of two surface antigens was studied by double staining with monoclonal antibodies to B cells, T cell subsets and follicular dendritic reticulum cells (DRC) using the avidin-biotin-complex (ABC) method in sections of human lymphoid tissues (tonsil, lymph node, spleen) and a non-lymphoid tissue, endometrium. Color mixture was avoided when an additional incubation with avidin-biotin-labeled peroxidase and subsequent development in the respective substrate of the first sequence preceded the second staining sequence using the primary antibodies at optimal concentrations. The antigenic profiles were portrayed by contrasting and distinct colors of the reaction products. It was observed that T lymphocytes of the cytotoxic/suppressor and helper/inducer phenotypes were topographically associated with each other and with B cells in B and T cell areas of lymphoid tissues as well as in lymphocytic aggregates in endometria. Subpopulations of these cells were mantled by processes of DRCs in lymphoid follicles. The findings indicate that the double ABC staining method can be used for simultaneous demonstration of two surface antigens in tissue sections.

Antibodies, Monoclonal↗
PubMed1986

Cell-mediated immunity in cat-scratch disease.

The importance of cell-mediated immunity in cat-scratch disease (CSD) is suggested by the positive skin test reactions and granulomatous histopathology noted in patients with this disease. However, an earlier investigation found that lymphocytes from patients with CSD and control subjects were equally unresponsive in vitro to cat-scratch antigen. In contrast, we found that 16 patients with CSD had significantly increased lymphocyte transformation responses to cat-scratch antigen when patients were compared to control subjects. This cell-mediated immune response may be directed against nonviable bacteria in the involved lymph nodes and may be the major mechanism responsible for the granulomatous reaction and clinical features of CSD.

Adolescent↗
PubMed1986

Once daily therapy for streptococcal pharyngitis with cefadroxil.

To determine if a single daily dose of cefadroxil would be effective in the treatment of group A beta-hemolytic streptococcal (GABHS) pharyngitis, 196 patients with GABHS pharyngitis were randomly assigned to receive either penicillin V 250 mg three times daily or cefadroxil 30 mg/kg once daily, for 10 days. Outcome was measured by the ability to isolate GABHS from the upper respiratory tract 18 to 24 hours after the onset of therapy, the impact on the clinical course, and the bacteriologic treatment failure rate. There was no significant difference in the number of patients in the cefadroxil and penicillin V treatment groups with throat cultures positive for GABHS at the 18 to 24-hour follow-up visit (0% and 2%, respectively), and the clinical responses of the patients in the two treatment groups were similar. Of the 99 patients in the three times daily penicillin V group, six (6%) had strains of GABHS isolated on one of the follow-up cultures that were identical to the strains isolated from their initial throat cultures and were considered to have bacteriologic treatment failures. Of the 96 patients in the once daily cefadroxil group, two (2%) were considered to have bacteriologic treatment failures. A single daily dose of cefadroxil appears to be as effective in the treatment of GABHS pharyngitis in this population as penicillin V given three times daily.

Adolescent↗
PubMed1986

Antigen detection test for streptococcal pharyngitis: evaluation of sensitivity with respect to true infections.

The clinical significance of false-negative results on antigen detection tests for group A beta-hemolytic streptococcal (GABHS) pharyngitis (negative test results and positive culture) has yet to be determined. We recently compared the Culturette Brand Ten-Minute Group A Strep ID Kit with blood agar cultures in 313 patients with pharyngitis, 257 (82%) of whom had positive throat cultures for GABHS. The Culturette Brand test had a sensitivity of 88%, specificity of 96%, a positive predictive value of 99%, and negative predictive value of 64%. More than half of the false-negative Culturette Brand test results occurred in children with less than 10 GABHS colonies on throat culture (1+ culture). When these 1+ cultures were not considered positive, the sensitivity of the Culturette Brand test was 93%. The sensitivity of the Culturette Brand test increased with an increased degree of positivity of the corresponding throat culture. Of the 31 children with false-negative Culturette Brand test results, 14 (45%) had a significant streptococcal antibody response; of the 224 children with true-positive Culturette Brand test results (positive test results and positive culture) from whom serologic data were available, 114 (51%) had a significant streptococcal antibody response. This difference is not statistically significant. These findings suggest that almost half of patients with false-negative results on antigen detection tests for GABHS pharyngitis have true infections (positive culture and antibody rise) and are not merely streptococcal carriers.

Adolescent↗
PubMed1986

Diagnosis of group A beta-hemolytic streptococcal pharyngitis. Use of antigen detection tests.

Early diagnosis and prompt initiation of antibiotic therapy for group A beta-hemolytic streptococcal pharyngitis can shorten the duration of the clinical illness and reduce the period of infectivity. This in turn may expedite a patient's return to school or day care, as well as a parent's return to work. Antigen detection tests are available that can provide a rapid diagnosis of group A beta-hemolytic streptococcal pharyngitis and can facilitate the prompt initiation of antibiotic therapy. In addition, these antigen detection tests can provide a rapid exclusion of group A beta-hemolytic streptococcal pharyngitis and thereby prevent the initiation of unnecessary antibiotics in patients with nonstreptococcal pharyngitis. However, before throat cultures on blood agar plates are totally abandoned and completely replaced by antigen detection tests, a number of additional studies are needed. The consequences of false-negative and false-positive antigen detection tests need to be determined. The accuracy of the antigen detection test as performed in physicians' offices needs to be compared with traditional culture methods performed in physicians' offices and not with an "idealized" standard. Finally, investigations need to be initiated to determine the impact of different antigen detection tests on the revenues and work flow in various practice settings, as well as their direct impact on patient care.

Anti-Bacterial Agents↗
PubMed1986

Variable expression of Ia antigens in human endometrium and in chronic endometritis.

Recent studies suggest that Ia antigens may be expressed in epithelial cells and that their expression may be under hormonal control. Therefore, the distribution of these antigens was studied in frozen sections of 37 human endometria with two monoclonal antibodies (Mab) to monomorphic determinants of Ia antigens using an avidin-biotin-complex (ABC) method. Five early proliferative, 9 midproliferative, 3 late proliferative, and 12 secretory endometria were examined. Two gestational endometria and six endometria with chronic endometritis were also used. Four consecutive sections from each case were stained for Ia, OKT8, Leu-3a, and B1 antigens. Throughout the cycle, the endothelial cells, many lymphocytes, and various monocytic-macrophagic cells in endometrial stroma were Ia positive. Furthermore, Ia antigens were localized to the normal endometrial epithelium. The intensity and the pattern of Ia expression, however, varied in different phases of the cycle. Ia antigens were stained weakly in endometrial glands and surface epithelium in early proliferative phase, and strongly in surface epithelium and glandular cells of the basalis and to a lesser extent of the functionalis in midproliferative and late proliferative phases. The expression of Ia antigens in epithelium was absent or focal during the secretory phase and in gestational endometria. Throughout the cycle and in gestational endometria, glandular cells in intimate association with lymphocytic aggregates were Ia positive. In chronic endometritis, the increased number of Ia positive stromal lymphoid cells was associated with a strong display of Ia antigens in epithelium. The findings indicate that, in addition to endothelial and lymphoid cells, Ia antigens are expressed in endometrial glandular and surface epithelial cells. This expression may be influenced by lymphoid cells in endometrium and by hormones.

Adult↗
PubMed1986

Characteristic histologic triad in liver adjacent to metastatic neoplasm.

More than 25% of undirected percutaneous liver needle biopsies that are performed in search of metastatic neoplasms yield false negative specimens. Often, however, histologic changes are observed in the liver adjacent to space-occupying lesions due to focal obstruction of bile and blood flow. These alterations were defined by semi-quantitative evaluation of 20 liver biopsy specimens with metastatic neoplasms, and revealed a characteristic histologic triad consisting of proliferated and abnormal bile ductules, polymorphonuclear leukocytes in edematous portal tracts and focal sinusoidal dilatation. When 15 patients with this combination of histologic alterations, but without malignant cells in liver biopsy specimens, were investigated prospectively, 13 patients (87%) were found to have hepatic metastases. Therefore, the observation of the histologic triad described here should lead to a continued search for space-occupying lesions in the liver.

Bile Ducts↗
PubMed1986

A comparison of cefadroxil and penicillin V in the treatment of streptococcal pharyngitis in children.

The efficacy of cefadroxil, an orally administered broad spectrum cephalosporin, was compared with that of penicillin V in several studies comprising more than 550 children with group A beta-haemolytic streptococcal (GABHS) pharyngitis. Both drugs alleviated clinical signs and symptoms and eradicated GABHS from the upper respiratory tract within 18 to 24 hours of the initiation of therapy. Approximately 8% of the patients treated with either cefadroxil or penicillin V had strains of GABHS isolated from 1 of their follow-up throat cultures which were identical to the strains isolated from their initial throat cultures, and were considered bacteriological treatment failures. Compliance was greater than 90% with all of the regimens used, but was significantly better with cefadroxil given as a 30 mg/kg dose once daily than with penicillin V given 3 times daily. There were no serious adverse reactions with either drug. Thus, cefadroxil was shown to be well tolerated and as effective as the standard agent, oral penicillin V, in the treatment of GABHS pharyngitis in children.

Cefadroxil↗
PubMed1986

Expression of HLA class I antigens on hepatocytes in liver disease.

Recent studies have demonstrated aberrant expression and topographical heterogeneity of HLA Class I and Class II antigens in tissues of patients with certain immunologic or neoplastic diseases. Current information about the expression of HLA antigens by normal and diseased hepatocytes is controversial. We analyzed the HLA antigenic profile of 4 normal fetal livers, 5 normal adult livers, 7 cases of chronic hepatitis B virus (HBV) infection, 14 cases of cirrhosis of various etiologies, 11 hepatic neoplasms, and 5 continuous cell lines derived from hepatic tumors. The specimens were tested by the indirect fluorescent antibody method with a panel of monoclonal antibodies to distinct monomorphic determinants of HLA Class I and Class II antigens and to beta 2-microglobulin. HLA Cells I antigens were not detected on normal fetal and adult hepatocytes, but were displayed on the plasma membrane of hepatocytes in the majority of all hepatic diseases tested and of the 5 hepatic tumor cell lines. There was a significant correlation between the expression of HLA Class I antigens on hepatocytes and the intensity of intralobular inflammation. Double immunofluorescent staining of livers infected with hepatitis B virus demonstrated simultaneous expression of HLA Class I antigens and HBsAg or HBcAg only in a small percentage of hepatocytes, suggesting lack of a specific association between HLA Class I and these viral antigens. HLA Class II antigens were not detected on hepatocytes from any of the liver diseases tested but were expressed by one of the 5 liver carcinoma cell lines analyzed. These findings confirm that HLA Class I antigens are not detectable within the limits of several immunohistochemical methods on normal hepatocytes and suggest that injury by a variety of factors directly or indirectly leads to induction of these antigens on the plasma membrane of hepatocytes.

Adolescent↗
PubMed1986

Induction of HLA-DR antigen expression in human endometrial epithelial cells in vitro by recombinant gamma-interferon.

Recent studies suggest that HLA-DR antigens may be inducible in some normal epithelial cells. Therefore, we studied the expression of these molecules in epithelial cell cultures derived from 9 proliferative and 7 secretory endometria with and without treatment by recombinant gamma-interferon (gamma-IFN). A panel of monoclonal antibodies to HLA-DR antigens, T cells, B cells, macrophages, endothelial cells, and cytokeratin was used to stain the cultured cells by the avidin-biotin complex method. The cultures consisted only of epithelial cells as demonstrated by expression of cytokeratin and by electron microscopy and did not contain any T or B cells, macrophages, or endothelial cells. The endometrial epithelial cells were HLA-DR-negative under routine culture conditions but expressed HLA-DR antigens after gamma-IFN treatment in a dose- and time-dependent fashion. The findings indicate that endometrial epithelium can actively synthesize HLA-DR antigens in vitro after induction by gamma-IFN.

Cells, Cultured↗
PubMed1986

Recent studies on the developing human hepatocellular carcinoma.

From our knowledge of characteristic phenotypic changes of the preneoplastic lesions during the stepwise evolution of hepatocellular carcinoma (HCC) in experimental models, we are now beginning to define the structural, histochemical, biochemical, antigenic and molecular properties of early HCC and of the putative preneoplastic changes in human liver. Histological, ultrastructural, morphometric and immunohistochemical studies suggest that adenomatous nodules of regenerating and hyperplastic hepatocytes are more likely to represent direct precursors of HCC than dysplastic hepatocytes. Histochemical and immunomorphological investigations show appreciable functional and phenotypic heterogeneity of human HCC as previously recognized in experimental hepatocarcinogenesis. Studies of altered expression of oncogenes in the regenerating liver and HCC are beginning to define the molecular mechanisms in cell growth and malignant transformation. Although integration of Hepadna viral DNA sequences frequently occurs during persistent infection in man and animals, the exact mechanism of viral oncogenesis remains to be elucidated. It is likely that the development of monoclonal antibodies to surface antigens on transformed hepatocytes will be useful for exploring lineage relationships between the cell populations involved in hepatocarcinogenesis.

Carcinoma, Hepatocellular↗
PubMed1986

Correlation of polyalbumin receptors with hepatitis B surface antigen polypeptides in human sera.

The molecular nature of the association between hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), polymerized human serum albumin receptors (pHSA-R), and HBsAg polypeptides is controversial. Therefore, we studied HBsAg, HBeAg, and pHSA-R by radioimmunoassay in sera of 27 patients with acute or chronic hepatitis B virus infection. In addition, the HBsAg polypeptides were demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining and immunoblot analysis. As a group, HBeAg-positive sera contained significantly more HBsAg and higher pHSA-R activity than HBeAg-negative sera. At a given amount of HBsAg, pHSA-R activity was significantly higher in HBeAg-positive sera than in HBeAg-negative sera. However, there was no correlation between the presence or absence of a particular HBsAg polypeptide and pHSA-R activity, suggesting that posttranscriptional events such as glycosylation may modulate pHSA-R activity associated with native HBsAg.

Acute Disease↗
PubMed1985

The aetiological agent of cat scratch disease.

A highly pleomorphic, gram-positive bacterium was cultured from an excised lymph node of a patient with cat scratch disease (CSD). The organism had morphological forms similar to those of the bacterium observed in Warthin-Starry stains of lymph node sections from CSD patients and may be the aetiological agent of this disease. Electron microscopic examination of lymph node sections from another patient with CSD showed organisms with morphological forms similar to those of the isolated bacterium. Biochemical and physiological analyses of this isolate suggested that it is not a commonly recognised contaminant or human pathogen and that it may be a member of the genus Rothia. This organism appears to resemble the bacterium that was identified as the aetiological agent of Parinaud's oculoglandular syndrome, a specific form of CSD, over 70 years ago.

Actinomycetaceae↗