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Biomedical subjects

J D Tyler

Publications and source records attributed to J D Tyler.

At least 19 recordsLinked to original sources
PubMed1996

Effects of azathioprine withdrawal in kidney recipients with stable function two years after transplant.

To assess the effects of azathioprine withdrawal, renal recipients with grafts > 2 yr function (103 study patients) were tapered off azathioprine over a 1-yr period and compared to 69 patients 2 yr after transplant who were not tapered (controls). Of the 103 study patients, 16 (15%) were living-donor transplants and 87 were cadaveric. Of the 69 control patients, 9 (13%) were living related transplants and 60 were cadaveric. The mean HLA match for those tapered was 3.3 Ag and 3.1 Ag for those remaining on azathioprine. Two study patients restarted azathioprine on their own. Age, sex, and cause of renal failure in both groups was similar. Of the 101 study patients remaining, 9 (8.8%) returned to dialysis due to biopsy proven chronic rejection. There were no acute rejection episodes. Six of the 69 control patients (8.7%) also returned to dialysis for the same reason. Of the 92 patients who have completed the taper, 85 have been off azathioprine for six or more months. There was not a significant difference between the mean 12- and 24-month creatinine levels of the study patients (1.6 mg%, 1.7 mg%) and those of the controls (1.5 mg%, 1.8 mg%). The mean 12- and 24-month hematocritis of patients tapered (41.3%, 40.8%) were comparable with patients not tapered (42.3%, 42.8%). Of interest, the mean hematocritis of both study and control patients rose from 28.9% and 33.5%, respectively, to 41.3% and 42.3% 1 yr following entry into the study. The mean 12- and 24-month white blood counts of those tapered (8.9, 8.7) did not differ significantly from those continued on azathioprine (8.8, 8.8). In stable renal transplant patients on triple drug immunosuppression for at least 2 yr, azathioprine can be discontinued, in a tapered protocol, without an increased risk of graft loss or compromise of renal function.

Azathioprine↗
PubMed1990

Factors affecting patency of venous allografts in miniature swine.

In immunologically defined National Institutes of Health miniswine, a segment of internal jugular vein was anastomosed to the carotid artery as an interposition graft. Patency of swine major histocompatibility complex matched, one haplotype mismatched, and complete mismatched veins was 9.8, 6.3, and 3.0 weeks respectively (p = 0.009). More than 90% of mismatched and 20% of matched allografts developed a positive crossmatch before occlusion (p = 0.006). The mixed lymphocyte response did not predict graft occlusion. Treatment of 10 swine with cyclosporine (10 mg/kg/day) did not significantly improve patency for one haplotype mismatched grafts. In haplotype mismatched veins, cryopreserved grafts occluded more rapidly than noncryopreserved grafts: mean 2.4 versus 6.3 weeks, respectively (p = 0.002). In all cryopreserved vein grafts, alloantibody appeared at or after graft occlusion rather than before occlusion as seen with fresh allografts (p = 0.046). The mean patency of cryopreserved versus fresh autografts was 3.3 and greater than 32 weeks, respectively (p = 0.004). In summary, these results indicate that (1) allograft patency is related to the degree of swine major histocompatibility complex match and development of cytotoxic alloantibodies; (2) moderate-dose cyclosporine does not prolong allograft patency nor suppress development of antibody; (3) cryopreservation may accelerate graft occlusion through nonimmunologic mechanisms.

Animals↗
PubMed1988

Tissue destruction resulting from the interaction of cytotoxic T cells and their targets.

In vitro and in vivo-generated cytotoxic T lymphocytes (CTL) specific for major and minor histocompatibility antigens evoked antigen-specific full-thickness skin necrosis when injected intradermally into allogeneic mice in a variety of strain combinations. In addition, CTL-target-cell mixtures injected intradermally into hosts syngeneic to the CTL also evoked destruction of host tissue. These "innocent bystander" reactions were evoked with alloreactive CTL as well as with CTL directed against hapten (TNP)-modified and virus (influenza A)-infected target cells. Unlike the direct reactions, the bystander reactions in histocompatibility-antigen systems occurred in spite of H-2 incompatibility of the CTL, admixed target cells, and the hosts. One explanation for these results, currently under investigation, is that some bystander reactions may occur without MHC restriction. In aggregate, our findings indicate that nonspecific as well as antigen-specific reactions initiated by CTL-target-cell interactions may contribute to tissue destruction in allograft rejection, in severe forms of delayed-type hypersensitivity, and in certain viral infections.

Animals↗
PubMed1987

Initial characterization of humoral IL-2 response inhibition following donor-specific transfusions under azathioprine immunosuppression.

A previous study indicated that noncompetitive humoral inhibition of IL-2-induced proliferation was a frequent consequence of donor-specific transfusions under azathioprine immunosuppression. In this report, we present our initial characterization of the mode of action and nature of this humoral activity. A direct role for azathioprine seems unlikely since its removal from post-DST+A sera did not eliminate inhibition, nor did addition of azathioprine to normal sera mimic the inhibition by post-DST+A sera. Inhibition of the proliferative response to IL-2 was observed on an individual cell basis after IL-2 stimulation that did not involve a direct effect on DNA synthesis. Inhibition appeared to require optimal IL-2 receptor expression as well as optimal doses of IL-2, suggesting that inhibition is manifested at the postreceptor level. Inhibition could not be removed by reconstitution with normal sera, indicating that post-DST+A sera were not deficient in a nominal serum component, which is necessary for optimal proliferation. The inhibitory activity in post-DST+A sera was sensitive to chemical reduction and heat. Inhibition of the response to IL-2 was readily demonstrated using IL-2 responsive human or murine T lymphocytes. However, post-DST+A serum also inhibited proliferation of one of two IL-2 independent cell lines. These results suggest that the inhibitory activity in post-DST+A plasma/serum may be due to the induction of an inhibitor of cell proliferation that is either lacking or "deficient" in normal serum.

Antibody Formation↗
PubMed1987

Preoperative immunomodulation of renal allograft recipients by concomitant immunosuppression and donor-specific transfusions.

The induction of immunologic unresponsiveness to improve renal allograft survival was attempted in 113 patients by the pretransplant administration of donor-specific whole blood or buffy coat in conjunction with continuous Aza immunosuppression. All donor/recipient combinations were at least 1-haplotype disparate and 17 were 2-haplotype disparate. Presensitization, defined as a positive Amos or antiglobulin T cell CM or a positive high-titer (greater than or equal to 1:8) B cell CM was present in 10 patients and not present in 103 patients. Attempts at desensitization of the already sensitized group were uniformly unsuccessful. Treatment of the 103 nonpresensitized patients resulted in transient sensitization in 3 patients, permanent sensitization in 8, and no evidence of sensitization in 92. Ninety-one nonsensitized patients underwent renal transplantation from the specific blood donor, and only 5 have experienced renal allograft rejection loss during a mean follow-up period of 26 months (6 to 70 months). Fifty-four percent have never experienced a rejection episode. The allograft survival rate at 2 years (91%) and 5 years (89%) is significantly better (P less than .01) than our historical experience with 1-haplotype living-related transplants at 2 years (66%) and 5 years (64%). The low rate of sensitization (8%) has permitted almost all patients to undergo eventual renal transplantation from the specific blood donor. This and the low rate of rejection (5%) argues for a modification of the immunologic response rather than a selecting out process as the mechanism for improved allograft survival.

Azathioprine↗
PubMed1986

Modulation of the response to interleukin 2 in recipients of donor-specific transfusions under azathioprine immunosuppression.

The effect of plasma from recipients of donor-specific transfusions given under azathioprine immunosuppression (DST+A) on the response to IL-2 was examined. Pre-DST+A plasma markedly enhanced the proliferative response to suboptimal doses of IL-2 by IL-2-dependent T cells, such that maximal responsiveness was achieved at lower IL-2 doses, as compared with normal plasma. Post-DST+A plasma also enhanced the response to suboptimal IL-2 doses. However at saturating IL-2 doses, the maximum response was markedly inhibited by post-DST+A plasma as compared with normal or pre-DST+A plasma. Neither toxicity nor inhibition of the IL-2 response was observed when the IL-2-dependent indicator cells were preincubated in post-DST+A plasma prior to an IL-2 dose-response assay. Of the recipients whose plasma was examined, nearly all exhibited some degree of inhibition (range: 8-50% inhibition) of the response to saturating levels of IL-2. Only one renal allograft has been lost in these recipients due to rejection, and this was an accelerated acute rejection in a recipient who had rejected 2 previous allografts and who developed a "transient" positive crossmatch to his donor during DST+A. The results suggest that inhibition of IL-2 responsiveness may be a frequent consequence of DST+A, and that the inhibition is dependent on an IL-2-mediated effect distinct from proliferation. Thus, such inhibition may contribute to the salutary effect of DST+A on renal transplantation.

Azathioprine↗
PubMed1986

Edwards Personal Preference Schedule correlates of addiction counselor effectiveness.

Edwards Professional Preference Schedule scores of 21 male and 10 female paraprofessional chemical dependency counselors working at inpatient treatment centers were correlated with ratings and rankings of effectiveness by supervisors and peers. Counselors judged as more effective scored higher on Dominance and Heterosexuality and lower on Order. When compared to their respective normative samples, both male and female counselors scored higher on Intraception and Heterosexuality and lower on Order and Endurance. The findings suggest that characteristics suitable for other types of counseling activities are not necessarily optimal for alcoholic and addiction counselors.

Adult↗
PubMed1985

Personality and psychophysiological variables in abusive, neglectful, and low-income control mothers.

This study was designed to systematically investigate personality, psychophysiological, and cognitive appraisal variables in three groups of mothers, i.e., abusive (N = 14), neglectful (N = 13), and low-income control (N = 15). All subjects completed a Mini-Mult, the Repression-Sensitization Scale, the Group Embedded Figures Test, the Multiple Affect Adjective Checklist, and the Socialization scale of the California Psychological Inventory. They listened to an audiotape sequence of white noise, tone, and infant's cry sounds while cardiovascular and skin resistance measures were recorded. The mothers also rated six dimensions of the infant's cry on a semantic differential. The three groups of mothers differed on a variety of personality variables, e.g., on F, Depression (D), Psychopathic Deviate (Pd), Psychasthenia (Pt), and Schizophrenia (Sc) from the Mini-Mult, on their cognitive appraisal of the infant's cry, and on skin resistance measures. A combination of personality, psychophysiological, and cry rating variables was entered in a discriminant analysis that was successful in discriminating 80% of the subjects. The two significant discriminant functions were defined primarily by the Pd scale and a cognitive appraisal measure.

Acoustic Stimulation↗
PubMed1984

Cloned LYT-2+ cytolytic T lymphocytes destroy allogeneic tissue in vivo.

The long-accepted notion that alloimmune cytolytic T cells (CTL) mediate transplantation immunity has recently been called into question. In order to ascertain directly whether alloimmune CTL can mediate destruction of foreign tissue, we tested the ability of mouse CTL expanded as cloned populations in vitro to destroy allogeneic skin in vivo. The results of these studies prove unequivocally that cloned Lyt-2+ CTL can perform this task in an immunologically specific, H-2-restricted, and dose-dependent fashion.

Animals↗
PubMed1984

Lysis of mouse macrophages, fibroblasts, and epidermal cells by epidermal alloantigen-specific cytotoxic T lymphocytes: effect of culture and inflammatory agents on Epa-1 expression.

The expression of Epa-1, a tissue-restricted non-major histocompatibility complex (MHC) alloantigen, on CBA epidermal cells (EC), fibroblasts (FB), and macrophages (M phi) was investigated using bulk-cultured and clonally-derived anti-Epa-1 cytotoxic T lymphocytes (CTL). Epa-1 was readily detected on freshly trypsinized and 24-hr-cultured EC, and on skin FB cultured for 1-3 weeks. In contrast, fresh peritoneal (PE) M phi were specifically resistant to Epa-1 CTL but became susceptible after 12-24 hr in culture. Epa-1 expression by PE M phi also could be induced in vivo by M phi-activating agents such as concanavalin A or Bacillus Calmette-Guérin (BCG), but not by the sterile inflammatory agents peptone broth or thioglycolate, suggesting a correlation between Epa-1 phenotype and M phi activation. From this and from parallel studies of spleen cell M phi it is concluded that Epa-1 may be a strain-specific marker for activated M phi in the mouse, as well as an inducible histocompatibility antigen in vivo.

Animals↗