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Biomedical subjects

A H Johnson

Publications and source records attributed to A H Johnson.

At least 127 records · Page 7Linked to original sources
PubMed1981

Statistical methods for studying homozygous typing cells of unknown specificity.

A situation can arise in D typing in which the HLA (A,B,C,D, or DR) specificities of the responders are known and the specificities of the HTC's are unknown. The most powerful and direct method of detecting association between the unknown stimulator (HTC) and any given HLA specificity is by comparing the observed double normalized values (DNV's) of individuals known to be positive for the specificity with the DNV's of negative individuals. This can be done by comparing the two groups with a Kolmogorov-Smirnov test (K-S test), an established statistical procedure for evaluating correlation between continuous variables, such as the DNV, and discrete variables (such as presence of D type). The application of the K-S test will generate as a "cutoff" value of point that maximizes the average of the frequencies of correct assignments in D positives and D negatives. We also propose an alternative method of computing the "r" value. We have analyzed 49 HTC's from the 8th International Workshop and present the association observed with the D and DR specificities.

Alleles↗
PubMed1980

Evidence for a new segregant series of B cell antigens that are encoded in the HLA-D region and that stimulate secondary allogenic proliferative and cytotoxic responses.

Five new histocompatibility antigens, designated secondary B cell or (SB) antigens, have been identified by secondary allogeneic proliferative and cytotoxic responses. The reagents used to define the SB antigents are lymphocytes primed between donors matched for all known HLA antigens. The SB antigens stimulate weak primary allogeneic proliferative responses (a mean relative response of 8%) but strong secondary proliferative responses. Strong secondary cell-mediated cytotoxicity is generated against target antigens that are distinguishable from the SB antigens defined by proliferation. Studies by direct lysis and by cold-target inhibition indicate that these target antigens are preferentially expressed on B cells relative to T cells. The SB antigens segregate with HLA, and the gene(s) encoding the SB1, 3, and 4 antigens maps centromeric to HLA-B. The SB antigens are major histocompatibility antigens not only because they are encoded by major histocompatibility complex (MHC) genes, but also by the functional criteria that the proliferative and cytotoxic responses to SB antigens are not restricted by HLA-DR or HLA-A,-B. Parallel studies of the SB antigens and the DR antigens with respect to: (a) their preferential expression on B cells, (b) their function in secondary allogeneic proliferative and cytotoxic respones, and (c) the location of their structural gene within the MHC. However, the SB antigens and the DR antigens are clearly distinct antigens, because population studies indicate that they can occur independently, and family studies indicate that specific SB antigens segregate with HLA haplotypes having different D and DR specificities. Our data are consistent with the hypotheses that the SB antigens are a new segregant series of B cell alloantigens, and that the SB gene and the DR gene derive from a duplicated ancestral gene.

Antigens, Surface↗
PubMed1980

HLA-linked B cell alloantigens of a new segregant series: population and family studies of the SB antigens.

In order to define the new human histocompatibility antigens, we have generalized primed lymphocytes using responder and stimulator cells matched for all recognized HLA-linked histocompatibility antigens (A,B,C,D,DR,MB). Many such primed lymphocytes give highly discriminatory proliferative responses specific for antigens which differ between HLA-A,B,C,D,DR, and MB matched restimulating cells. Five distinct antigens have been defined which appear to be part of a single segregant series (designated "SB"). Studies in a DR/GLO recombinant family indicate that the antigens are coded by an HLA-linked gene telomeric to GLO. Family studies of 57 HLA haplotypes provide an estimate of genotype frequency which is 12% or less for four of the SB alleles but approximately 50% for the most common (SB4, which may be a "public: determinant); approximately 25% of haplotypes are blank. Population studies of one of the SB antigens (SB1) suggest that it is in linkage disequilibrium with the SB antigens are part of a highly polymorphic new segregant series of B cell alloantigens encoded by a gene that maps between HLA-B and GLO.

B-Lymphocytes↗
PubMed1980

In vitro and in vivo reactivity and specificity of fractions from sonicates of Mycobacterium tuberculosis separated by gradient acrylamide gel electrophoresis.

Fractions of cell sonicates from the H37Rv strain of Mycobacterium tuberculosis prepared by gradient acrylamide gel electrophoresis (GAGE) were examined by immunoelectrophoretic analysis and tested for biologic reactivity and antigenic specificity. Each was tested for the ability to elicit delayed type hypersensitivity reactions in the skin of guinea pigs sensitized with M. tuberculosis, M. kansasii, M. intracellulare (Battey), M. scrofulaceum (Gause), and M. fortuitum. Peripheral lymphocytes from persons infected with mycobacteria were also exposed to fractions, and the increase in [3H]thymidine incorporation into DNA was used as an index of stimulation (lymphocyte transformation). Only 4 fractions (6, 11, 12, and 16) were found to be significantly more specific than the unfractionated sonicate, and none was monospecific for M. tuberculosis. The results of fused rocket immunoelectrophoresis suggested that incomplete separation of antigens and/or shared group-specific multideterminant antigens may have accounted for the observed cross-reactions.

Animals↗
PubMed1980

Analytical gradient polyacrylamide gel-crossed line immunoelectrophores. A technique for locating species specific Mycobacterium tuberculosis H37RV antigens in polyacrylamide gel columns.

Analytical gradient polyacrylamide gel electrophoresis of antigens from Mycobacterium tuberculosis H37RV was combined with crossed line immunoelectrophoresis to locate the position of antigens in polyacrylamide gel columns that appeared to be specific for M. tuberculosis H37RV. Specificity was established by comparing H37RV with M. kansaii CE in the electrophoretic procedure and the relative mobility (Rm) values are being used in an effort to recover and enrich specific antigens from preparative gel columns. Such fractions should be more suitable in efforts to recover purified monospecific components from M. tuberculosis H37RV.

Antigens, Bacterial↗
PubMed1980

Resident development in family practice training: a personal counseling program.

A family physician's personal development and professional functioning are strongly meshed. Family practice residencies need to implement programs which promote personal development and support the integration of the resident's personal and professional development. This paper describes and evaluates the personal counseling program in the Department of Family Medicine, Medical University of South Carolina, from 1973 through 1978. The evolution of goals and their implementation are outlined. Providing resident counseling as part of a family medicine curriculum presents problems which are generic to primary care. These problems and their solutions, within the model of resident development, are defined and addressed.

Counseling↗
PubMed1980

Characterization of prostate cells.

It is obvious from this brief review that the weakest link in the successful application of in vitro models to answer questions related to prostatic cancer is the lack of adequate markers to permit characterization of the cells with regard to organ and tissue origin and their neoplastic status. In our opinion there is little to be gained in defining markers for other purposes until we can manage these basic areas of recognition.

Cell Differentiation↗
PubMed1979

B cell antigens of Black Americans.

Fourty-four unrelated North American Blacks and one Black family were tested for B-cell specific antigens with 7th International Workshop antisera. DR specificities were clearly defined in this group, but were generally less frequent than reported for Black Americans in the 7th Workshop report and were most similar in frequency to those reported for African Blacks. Five new B-cell specificities (DuB40-43, 45) were identified. In contradistinction to Caucasians, Black Americans type for HLA-D with homozygous typing cells failed to exhibit strong linkage disequilibrium between D and DR types.

B-Lymphocytes↗
PubMed1979

Teaching attitudes and skills in microcounseling.

This is the first of two papers describing salient aspects of the behavioral science orientation curriculum in the Charleston Family Practice Residency that focus on developing counseling skills. Two short lectures preceding microcounseling training are summarized. One short lecture outlines the myth of medical management and differentiates a "problem oriented" from a "client oriented" model. The second short lecture presents the definition of communication as a culturally structured complementary series of behaviors. Microcounseling, which is an experientially oriented series of communication exercises, is presented in detail. The article concludes with a discussion of the specific advantages and disadvantages of this particular learning format and its implications for the practice of family medicine.

Communication↗
PubMed1979

Assessing counseling skills and attitudes in family practice residents.

This is the second of two papers describing portions of the behavioral science orientation curriculum that focuses on assessing changes in counseling skills and attitudes in Charleston family practice residents. The measurement of counseling skills and attitudes is accomplished through a 38-item multiple choice instrument. The basic types of items composing the instrument are delineated. Pre and post-testing data are presented over a five-year period, 1973-1977. Three-year follow-up data are presented for the residency class entering in 1975. These data are discussed from two perspectives: (1) their function in teaching physician awareness of counseling style, and (2) their function in assessing changes in physician counseling profiles.

Attitude of Health Personnel↗