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L Thacker

Publications and source records attributed to L Thacker.

At least 19 recordsLinked to original sources
PubMed2001

HLA phenotypes of ESRD patients are risk factors in the panel-reactive antibody (PRA) response.

To determine whether recipient HLA phenotypes are correlated with an increased or decreased risk of alloantibody sensitization in end-stage renal disease (ESRD) candidates for first or repeat kidney transplantation; we analyzed 19440 kidney allograft recipients consisting of 13,216 Caucasians and 6224 non-Caucasians transplanted between 10/87 and 11/98 at South-Eastern Organ Procurement Foundation (SEOPF) member institutions. Relative risk values and 95% confidence limits were obtained using Wolfe's method. Logistic regression was used to adjust for covariates that influence sensitization, i.e. ethnicity, gender, age, pregnancies, transfusions, primary/repeat transplant and living versus cadaver donor. Univariate analysis of the entire cohort indicated that nine HLA allelotypes (DR1,4,7; B8,12,40; A1,2,11) were associated with a significantly reduced risk of sensitization, and five allelotypes (B42,B53; A 10,19,36) were associated with an increased risk of PRA responses. Corrected for the number of statistical comparisons, recipients with DR1, DR4, A1 or A2 were 15% less likely to be sensitized per allelotype. Recipients with B42, B53 or A36 were at increased risk of preformed antibodies, after correction of the P value, for an average of 38% increased risk per allelotype. In the multivariate analysis, HLA phenotypes identified as independent risk factors associated with protection against sensitization were DR1,4,7; B12(44,45); and A1,2, with an average reduced risk of 9% per allelotype. The only independent susceptibility allelotype was A36 with an increased risk of 29%. The A10 (25,26,34,66) group reached borderline significance. We also looked for HLA-DR,-B,-A combinations that could potentially represent protective or at risk haplotypes/genotypes. Stepwise logistic regression identified five combinations associated with protection: DR1-B35-A3; DR1-B35-A2; DR1-B44-A2; DR4-B44-A2; DR7-B57-A1 (RR range 0.83-0.63) with 27% average reduced risk per combination. Phenotype combinations associated with an increased risk of sensitization were: DR2-B44-A2; DR2B53-A2; DR3-B8-A1: DR3-B42-A30; DR6-B42-A30; DR11-B53-A30 (RR range 2.76-1.48) with an average increased risk of 70% per combination. This study provides strong evidence that HLA-linked genes influence the anti-HLA PRA response. The magnitude of the altered PRA response risk in DR-B-A combinations was approximately twice that of the allelotypes at individual loci. HLA-DR genes seemed to contribute most of the altered risk. The correlations between DR types and PRA responsiveness are consistent with the DR types previously regarded as predictors of kidney graft survival. The magnitude of increased PRA risk attributable to an allelotype or combination was approximately twice that associated with a decreased risk. We conclude that some HLA class II-linked genes modulate the PRA response in a clinically significant manner. This immune response gene (Ir) regulation probably operates through polymorphic HLA molecules in their physiologic roles of antigen processing and presentation to helper T cells.

Adult↗
PubMed1997

Regional organ procurement (ROP) trays in renal allograft distribution and outcome.

ROP trays containing patient serum samples and distributed by the South-Eastern Organ Procurement Foundation (SEOPF) were instituted to increase the likelihood of transplanting potential renal recipients who are highly sensitized to HLA antigens. This study examines kidney distribution and transplant outcome to assess equitable placement and clinical function post transplant with and without the use of ROP trays. Data were collected over a 26-month period on the distribution of kidneys from 328 consecutive SEOPF donors from whom at least 1 kidney was procured. Shared kidneys were placed via the UNOS and SEOPF-variance computer match programs. Of 656 kidneys, 596 were placed into 582 recipients; 60 were not used. ROP trays were used in placement of 492 kidneys and were not used for placement of 104 kidneys. Outcome was determined for 435 kidneys transplanted into SEOPF recipients. Only 33 (6.9%) recipients with ROP tray use and 10 (9.8%) without were sensitized to HLA. A 10% increase in placement to the originally intended recipient was seen with ROP tray usage over kidneys placed without ROP tray use (p < or = 0.025). Recipients matched using ROP tray data averaged 29 positions higher on the match printout. There was no difference in tray use regarding placement of kidneys within or outside the donor's local UNOS region, nor was there a difference in mean HLA match of transplant pairs with and without ROP tray use, 3.2 and 3.1 antigens, respectively. Cold ischemia time was similar, 22.9 and 23.6 h, respectively, for kidneys placed with and without ROP trays. At post-transplant discharge, there were no differences in patient status, graft failure, rejection treatment, dialysis need, or urine output whether or not ROP trays were used. Significantly, however, plasma creatinine at discharge and at 12 months was lower for those placed with ROP trays (2.5 mg/dl and 1.7 mg/dl) vs (3.1 mg/dl and 1.9 mg/dl), respectively. During this time period, all kidneys transplanted with use of ROP trays functioned as well or better than those transplanted without ROP tray placement. Thus, the use of ROP trays appeared to have a beneficial effect in getting more recipients of higher priority transplanted with equivalent, if not better, graft function.

Cold Temperature↗
PubMed1996

Self-report measures of schizotypy as indices of familial vulnerability to schizophrenia.

While structured psychiatric interviews have generally succeeded in identifying higher rates of schizotypal personality disorder in relatives of schizophrenia versus control probands, self-report questionnaires designed to assess schizotypy have been less successful at distinguishing these groups of relatives. In the Roscommon Family Study, an epidemiologically based, case-controlled study conducted in the west of Ireland, relatives were administered a short form of Eysenck's Psychoticism scale and shortened and modified versions of the scales for magical ideation and social anhedonia developed by Chapman and colleagues. We compared, with relatives of matched controls, relatives of four proband groups: schizophrenia, other nonaffective psychoses (ONAP), psychotic affective illness (PAI), and nonpsychotic affective illness (NPAI). Only social anhedonia scores successfully differentiated, at modest levels of significance, relatives of schizophrenia versus control probands. Levels of magical ideation did not distinguish relatives of schizophrenia, ONAP, PAI, or NPAI probands from relatives of controls. Compared to controls, ONAP probands had significantly elevated psychoticism scores, but no such increase was seen in relatives of schizophrenia, PAI, or NPAI probands. Dimensions of schizotypy assessed at personal interview were significantly better at differentiating relatives of schizophrenia and control probands than our measures of social anhedonia, magical ideation, or psychoticism. Although psychiatric interviews in this sample have shown that clinically assessed schizotypal personality disorder and traits strongly aggregate in relatives of schizophrenia patients, of the three self-report instruments designed to assess schizotypy, only one even modestly identifies relatives of schizophrenia versus control probands. These results suggest that, compared with psychiatric interviews, self-report questionnaires are less successful at assessing underlying familial vulnerability to schizophrenia.

Family↗
PubMed1990

Living-donor renal transplantation in SEOPF. The impact of histocompatibility, transfusions, and cyclosporine on outcome.

The impact of haplotype match (HM), pretransplant transfusions, and cyclosporine use were examined for living-donor renal transplants performed among 49 centers in the South-Eastern Organ Procurement Foundation (SEOPF) from November 1983 to June 1988 with follow-up through March 1989. During this period, 750 2-HM, 1246 1-HM, and 120 0-HM living-donor transplants were performed at 46, 47, and 27 centers, respectively. Demographic comparisons of the HM categories demonstrated the greatest use of cyclosporine and donor-specific transfusions in the 0-HM group, and the greatest use of random blood transfusions (RBT) or no blood transfusions (NBT) in the 2-HM group. By univariate and multivariate (Cox regression) analyses, actuarial graft survival was significantly associated with haplotype match, although excellent 3-year graft survival was seen for 0-HM as well as 1-HM and 2-HM first transplant recipients: 74 +/- 5%, 80 +/- 2%, and 85 +/- 2%, respectively. Comparisons were also made among patients receiving DST +/- CsA, RBT +/- CsA, and NBT +/- CsA for each HM group by univariate and multivariate analyses. For 0-HM recipients, DST + CsA was most frequently used and associated with the best long-term survival (86 +/- 5% at 3 years) by univariate analysis. For 1-HM recipients, there were no apparent differences in graft survival between DST and RBT groups +/- CsA by univariate analysis, but the absence of transfusion (NBT +/- CsA) was associated with the poorest 3-year survival (79 +/- 4%). This was confirmed by multivariate analysis, where DST (P less than 0.06) and RBT (P less than 0.02) were each significantly associated with graft survival, and provided relative benefits (vs. NBT) of 0.56 and 0.44, respectively; CsA use was not significantly associated with outcome or a significant benefit. For 2-HM recipients, the poorest results were seen with DST + CsA (78 +/- 6% at 3 years) by univariate analysis; multivariate analysis suggested no benefit with DST or RBT, and an increased risk of graft loss with CsA. These results indicate that the use of pretransplant transfusions and CsA therapy may have differential benefits depending upon HM in living-donor renal transplantation.

Adolescent↗
PubMed1984

Detection of soluble Legionella pneumophila antigens in serum and urine specimens by enzyme-linked immunosorbent assay with monoclonal and polyclonal antibodies.

Urine and serum specimens from three patients with pneumonia caused by Legionella pneumophila serogroup 1 (Lp1) were tested by enzyme-linked immunosorbent assay (ELISA) for Lp1-soluble antigen. A three-layer direct ELISA with polyclonal antibodies and a four-layer indirect ELISA with both polyclonal and monoclonal antibodies were used. Lp1 antigen was detected in both urine and serum from the three patients. As determined by ELISA, the concentration of antigen was 30- to 100-fold less in serum than in urine collected on the same day. In some instances the indirect ELISA was more sensitive than the direct ELISA, but in others it was less sensitive, depending on the monoclonal antibody used. The subgroup of the infecting Lp1 organism was determined based on antigenic determinants expressed in the urine. This study illustrates the use of serum as well as urine as an antigen reservoir in the laboratory diagnosis of legionellosis by ELISA and the potential for developing more sensitive antigen detection systems by the judicious use of monoclonal antibodies.

Animals↗
PubMed1983

Determination of antigenic relationships among legionellae and non-legionellae by direct fluorescent-antibody and immunodiffusion tests.

Six isolates, five from water samples and one from a human tracheal swab taken at autopsy, reacted strongly with working dilutions of Legionella fluorescent-antibody conjugates. Of these, two isolates of Pseudomonas fluorescens (EB and CDC93), one isolate of the Flavobacterium-Xanthomonas group (CDC65), and one isolate of P. alcaligenes (CDC11) reacted with Legionella pneumophila serogroup 1 conjugate. P. alcaligenes ABB 50 reacted with an L. pneumophila serogroup 3 conjugate and of P. maltophilia reacted with the L. micdadei conjugate. Antisera and labeled conjugates were prepared for these new cross-reacting isolates, and their relationships to the legionellae were examined by direct fluorescent-antibody and immunodiffusion tests. A nonreciprocal cross-reaction existed between L. micdadei and P. maltophilia and also between serogroups 3 of L. pneumophila and P. alcaligenes ABB50. Of the four isolates that reacted with serogroup 1 of L. pneumophila, P. fluorescens CDC93 had the strongest relationship, and the other three had only minor relationships. Although cross-reactivity among non-legionellae and legionellae has not been a major problem, these findings are relevant to the interpretation of direct fluorescent-antibody tests for detecting these bacteria.

Antigens, Bacterial↗
PubMed1983

Monoclonal antibodies to Legionella pneumophila serogroup 1: possible applications in diagnostic tests and epidemiologic studies.

Monoclonal antibodies were produced against two strains of Legionella pneumophila serogroup 1. A panel of nine monoclonal antibodies were selected for their unique specificities observed in indirect fluorescent antibody tests with 130 strains of L. pneumophila serogroup 1. One monoclonal antibody was reactive with an antigen possessed by 128 of 130 strains. Two major subgroups were identified and 13 different antigen patterns were observed among the 130 serogroup 1 strains.

Animals↗
PubMed1979

Isolation of Legionella pneumophila from nonepidemic-related aquatic habitats.

Continuous centrifugation of large volumes of water from natural southeastern lakes allowed quantitative detection of Legionella pneumophila by direct immunofluorescent staining. Positive samples were injected intraperitoneally into guinea pigs, and the L. pneumophila were isolated and identified by their morphological, cultural, physiological, and serological characteristics.

Animals↗
PubMed1979

Recognition of a new serogroup of Legionnaires disease bacterium.

A strain of the Legionnaires disease bacterium (LDB) that was isolated by Joseph E. McDade from a postmortem lung specimen of a patient with fatal atypical pneumonia at the Veterans Administration Hospital in Togus, Maine was serologically different from 16 other strains of LDB that had been isolated previously from patients in other geographic locations. The serological differences of the Togus isolate were shown in results of direct and indirect fluorescent antibody staining and of immunoelectrophoresis with soluble antigen extracts. Seroconversion for the Togus strain of LDB in acute- and convalescent-phase sera from a second patient with atypical pneumonia at the Veterans Administration Hospital in Togus indicated that this patient had been infected with an LDB that was serologically similar or identical to the Togus isolate. The Togus serogroup of LDB should be considered when performing serological tests for Legionnaires disease.

Antigens, Bacterial↗
PubMed1979

Four serogroups of Legionnaires' disease bacteria defined by direct immunofluorescence.

Thirty-five strains of Legionnaires' disease bacteria were shown to belong in four distinct serologic groups on the basis of findings obtained with direct fluorescent antibody testing. Thirty of the strains were placed in group 1, three in group 2, one in group 3, and one in group 4. Immunoelectrophoretic studies showed both unique and common antigens among the representative strains of the four serogroups.

Antigens, Bacterial↗
PubMed1978

Improved immunoadsorption procedure with anion-exchange bacterial cell columns.

Bacterial cell columns for immunoadsorption were prepared with Streptococcus cells and triethylaminoethyl cellulose (Cellex-T) matrix material as a model system. Good column flow properties and satisfactory retention of the cells were obtained with ratios as high as 2 ml of packed cells/3 g dry weight of cellulose. Anion-exchange fractionation of whole serum by the Cellex-T was prevented by using 0.25 M NaCl in the developing buffer. Antibodies were adsorbed directly from whole serum and recovered in high yield by desorption at pH 2.3. Pre-exposing bacterial cells to formalin and washing them with acetone was necessary to ensure that they remained on the columns. One strain of Streptococcus salivarius (SS 908) was satisfactorily retained on a column only after cells were labeled with fluorescein isothiocyanate and washed with acetone. The means by which Cellex-T retains bacterial cells appears to be a combination of electronic attraction and physical entrapment.

Chromatography, Ion Exchange↗
PubMed1978

Detection of Legionnaires disease bacteria by direct immunofluorescent staining.

Antisera and fluorescein isothiocyanate conjugates prepared for five strains of the Legionnaires bacteria were tested in both homologous and heterologous staining reactions with 10 isolates of the organism from patients in seven geographic areas. The strains were related but not identical as judged by the results of direct immunofluorescence staining. The conjugates were successfully used to detect Legionnaires disease bacteria in Formalin-fixed lung scrapings, in histological sections, and in fresh lung tissue obtained at biopsy or autopsy. In addition, the labeled antibodies are valuable for staining suspected cultures of the bacterium and for searching for the source of these organisms in soil, water, and other environmental niches. The reagents are highly specific for detecting the Legionnaires organism in clinical specimens.

Bacteria↗
PubMed1976

Diethylaminoethyl-cellulose-bacterial cell immunoadsorbent columns: preparation of serotype-specific globulin and immunofluorescent conjugates for Streptococcus mutans serotypes a and d.

Diethylaminoethyl (DEAE)-cellulose was used as a support material for preparing bacterial cell columns. Pretreatment of the bacterial cells with formalin was essential in obtaining satisfactory adherence of the cells to DEAE-cellulose. Cross-reacting antibodies were removed from antibody preparations against strains of Streptococcus mutans serotypes a and d by adsorption on appropriate bacterial cell columns. S. mutans serotype d was further divided into two subtypes on the basis of immunofluorescent staining with conjugates of immunospecifically adsorbed immunoglobulin G. The DEAE-cellulose-bacterial cell columns were regenerated after use by desorbing the cross-reacting antibodies with low-pH buffer and were used repeatedly over and 18-month period with no detectable loss in effectiveness.

Adsorption↗