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M L Rose

Publications and source records attributed to M L Rose.

At least 73 records · Page 4Linked to original sources
PubMed1996

Inhibition of the transendothelial migration of human lymphocytes but not monocytes by phosphodiesterase inhibitors.

This study describes an in vitro model of peripheral blood mononuclear cell (PBMC) migration through human endothelial cells, held on polycarbonate inserts, which allows automatic differential counting of migrated cells as lymphocytes and monocytes. Using this system it was found that treatment of PBMC with the phosphodiesterase (PDE) inhibitors theophylline (at 1 and 10 micrograms/ml) and RO-20-1724 (at 1 microM) inhibited the migration of the lymphocyte component to 64.2+/-16.4%, 48.9+/-3.0% and 47.5+/-5.8% of the control values, respectively, while the migration of the monocytes component was largely unaffected. The PDE inhibitors needed to be present during the assay to inhibit migration, whereas pre-treatment of either the endothelium or the PBMC did not consistently effect lymphocyte migration. The drugs also inhibited the migration of lymphocytes through control inserts, either uncoated or coated with fibronectin, suggesting that some of the inhibition is an effect on lymphocyte motility rather than lymphocyte-endothelial interactions. Lymphocyte migration through fibronectin-coated filters was significantly enhanced compared with uncoated filters. Activation of the PBMC by anti-CD3 MoAb increased motility and migration by up to 300%. This migration appeared to be greatly inhibited by the PDE inhibitors, although the effect was complicated by problems of lymphocyte aggregation. This study provides a novel method of measuring mononuclear cell transendothelial migration, and suggests a possible role of PDE inhibitors in reducing this progress.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed1996

Alloproliferation of purified CD4+ T cells to adult human heart endothelial cells, and study of second-signal requirements.

Human endothelial cells have been shown to be capable of causing direct allostimulation of T cells. However, the majority of immunological studies of human endothelial cells have been performed on cells of fetal origin. Here we use endothelial cells isolated from the adult human heart, both large vessel (coronary artery, pulmonary artery and aorta) and also microvascular. We have examined the ability of all these endothelial cells to cause direct allostimulation of T cells, and show that purified CD4+ T cells can proliferate in response to adult human heart endothelial cells, the response being dependent on pretreatment of the endothelial cells with interferon-gamma (IFN-gamma) and inhibited by anti-HLA-DR monoclonal antibody. The proliferative responses of CD8+ T cells to adult but not fetal endothelial cells was inconsistent and weak. Proliferative responses were not blocked by CTLA4-Ig, which inhibits T-cell responses to "classical' antigen-presenting cells (APC), but > 50% inhibition was achieved with monoclonal antibody to lymphocyte function-associated antigen-3 (LFA-3). These results show that adult human cardiovascular endothelial cells are capable of causing allostimulation of resting CD4+ T cells, using a different second signal to classical APC. In view of these findings endothelial cells should be considered as APC following solid organ transplantation.

Adult↗
PubMed1996

Effect of human cytokines (IFN-gamma, TNF-alpha, IL-1 beta, IL-4) on porcine endothelial cells: induction of MHC and adhesion molecules and functional significance of these changes.

Previous studies using cultured human endothelial cells have demonstrated the role of inflammatory cytokines [interferon-gamma (IFN-gamma), tumour necrosis factor-gamma (TNF-alpha), interleukin-1 beta (IL-1 beta) and IL-4] in the regulation of major histocompatibility complex (MHC) and adhesion molecule expression. These cytokines are therefore implicated in the amplification of allograft, and more recently xenograft, rejection. In view of the likely event of grafted porcine tissues being exposed to human cytokines, we have investigated the effect of IFN-gamma, TNF-alpha, IL-1 beta, IL-4 and recombinant porcine IFN-gamma (rpoIFN-gamma) on cultured porcine aortic endothelial cells (PAEC) with respect to induction/up-regulation of porcine MHC and adhesion molecules and B7 receptors. Expression was detected using monoclonal antibodies (mAb) against porcine ligands and human CTLA-4-immunoglobulin; binding was analysed by flow microfluorimetry. TNF-alpha but not the other human cytokines unregulated swine leucocyte antigens (SLA) class I, class II and B7 receptor expression and induced vascular cell adhesion molecule (VCAM) and E-selectin expression. Porcine IFN-gamma also up-regulated SLA class I and class II, the ligand for CTLA-4-immunoglobulin and VCAM expression; the magnitude and kinetics of this response differed to that produced by recombinant human TNF-alpha (rhTNF-alpha). The ability of untreated, rpoIFN-gamma- and rhTNF-alpha-treated PAEC to stimulate CD4+ T cell was compared. CD4+ T-cell proliferation and IL-2 production were significantly enhanced by rhTNF-alpha and rpoIFN-gamma, rpoIFN-gamma being more effective than rhTNF-alpha. Use of blocking antibodies and CTLA-4-immunoglobulin demonstrated that the enhanced proliferative response, but not apparently IL-2 production, was dependent on cytokine-mediated up-regulation of SLA class II and B7 receptors. In conclusion, human TNF-alpha acts as a proinflammatory cytokine on PAEC and is likely to enhance the cellular response to xenogeneic organs in vivo.

Animals↗
PubMed1995

Reduction of cellular rejection and increase in longer-term survival after heart transplantation after HLA-DR matching.

HLA matching in cardiac transplants is perceived as being logistically difficult. We studied 1135 consecutive primary cardiac allografts between 1980 and 1994 to assess the effect of HLA mismatching on long-term graft survival and cellular rejection episodes within 3 months of transplantation. We found a significant association between HLA-DR mismatching and the number of episodes of rejection (no mismatch 0.80 [SE 0.13], one mismatch 1.22 [0.06], two mismatches 1.42 [0.06], p < 0.05). We found a similar correlation between the total number of biopsy specimens showing evidence of cellular rejection and HLA-DR mismatch. The time between operation and the first rejection episode shortened with increasing HLA-DR mismatch (no mismatch 85.5 [37.3] days, one mismatch 43.1 [8.1], two mismatches 24.1 [2.9], p < 0.05). Furthermore, the proportion of patients with no evidence of rejection correlated with HLA-DR incompatibility. A significant association between improved graft survival and HLA-DR mismatching was found over 1, 5, and 10 years after transplantation (no mismatch 1 year 92%, 5 years 83%, 10 years 76%, one mismatch 1 year 81%, 5 years 73%, 10 years 59%, and two mismatches 78% 1 year, 5 years 70%, and 10 years 52%, p = 0.02). Increased efforts to prospectively HLA match patients has resulted in 25% of patients transplanted between January and May 1995 (n = 13/52) receiving grafts matched for HLA-DR. HLA matching reduces the frequency and severity of acute cardiac allograft rejection and improves graft survival for up to 10 years. Our preliminary results suggest that it is possible to use HLA matching prospectively for our selection of recipients.

Actuarial Analysis↗
PubMed1995

Direct recognition of SLA- and HLA-like class II antigens on porcine endothelium by human T cells results in T cell activation and release of interleukin-2.

To investigate whether human T cells can directly recognize pig xenoantigens, highly purified human CD4+ and CD8+ T cells were incubated with pig aortic endothelial cells (PAEC). The response was measured by [3H]thymidine uptake and release of bioactive interleukin-2. A detailed examination of MHC expression by cultured PAEC and tissue sections of porcine aorta and heart showed porcine endothelial cells (EC) to be constitutively positive for SLA class II and antigens that crossreact with HLA class II molecules. Low level expression of B7 receptors was detected by binding of both human and mouse CTLA-4-Ig to untreated PAEC, which was enhanced significantly by treatment with recombinant porcine interferon-gamma. Human T cells, purified by positive selection and residual DR+ cells removed by lymphocytolysis, were shown to be functionally free of monocytes. Untreated PAEC elicited strong proliferation by human CD4+ T cells: CD8+ T cells also proliferated, but more weakly. This response was inhibited by CTLA-4-Ig. Blocking studies were performed with mAbs that bind to PAEC and not human EC (MSA3, TH16B), an mAb that binds to human and porcine EC (DA6.231), and L243, which binds to human and not porcine EC. The proliferative response of CD4+ T cells to PAEC was inhibited significantly by mAbs against swine and human determinants. In contrast, the response of CD4+ T cells to human EC was inhibited only by mAbs against human determinants. Experiments that directly compared the CD4+ and CD8+ T cell responses to PAEC and the human EC line EAhy.926, both with and without prior treatment with species-specific interferon gamma, demonstrated greater proliferation and 5-10 times more interleukin-2 in response to pig EC than to human EC.

Abatacept↗
PubMed1995

Humoral immune response to human aortic valve homografts.

The humoral response to homograft valves in humans is largely unknown. The anti-human lymphocyte antigen (HLA) antibody production, specificity, and immunoglobulin class were examined sequentially in 73 patients undergoing aortic valve replacement. In addition, the long-term production of antibodies was examined in a cross-sectional study of 160 patients at periods varying from 1 to 15 years postoperatively. Human lymphocyte antigen antibodies were produced in 17 of 30 antibiotic-sterilized homografts (56%) and in 15 of 15 "homovital" homograft recipients, compared with 6 of the 28 control xenograft recipients (21%) (p < 0.001). The HLA antibodies were immunoglobulin G in all 15 homovital homografts, in 11 of 17 antibiotic-sterilized homografts, and in four of the six xenograft cases. Human lymphocyte antigen specificities could be assigned to the antibodies in 21 cases. In 10 of 11 cases in which donor HLA typing data were available, the antibodies detected were directed against donor HLA class I antigens. Of six possible determinants of HLA antibody production, the type of homograft valve implanted (homovital or antibiotic sterilized) correlated with antibody formation. In the cross-sectional study, 66 of the 85 homovital homograft recipients tested for HLA antibodies after 1 year were found to have antibodies, compared with 29 of 75 antibiotic-sterilized homograft recipients (p = 0.00003). We conclude that homografts appear to stimulate a strong donor HLA-specific antibody response, particularly of the immunoglobulin G class. This is most common in homovital valve recipients. These antibodies can persist for 15 years after operation. The clinical significance of this response requires further investigation.

Antibody Specificity↗
PubMed1995

Pre-transplant anti-epithelial cell antibodies and graft failure after single lung transplantation.

Eighty-five patients undergoing single lung transplantation have been studied to determine the presence of anti-epithelial cell antibodies (AECA) prior to transplantation using the human lung carcinoma epithelial cell line A549 in a microcytotoxicity assay. In addition, 29 healthy volunteers were also assayed for the presence of AECA. Twenty-seven of the 85 recipients exhibited AECA prior to transplantation compared to none of the 29 control subjects (p = 0.0001). Actuarial graft survival at 1 year was 78% for the AECA negative group compared to 56% for AECA positive recipients (p = 0.01). No correlation was seen between the presence of AECA and graft rejection as determined by transbronchial biopsy. However, there was an association between AECA and post-transplant infection (p = NS) where 16 (64%) of the AECA positive recipients had postoperative infection episodes compared to 25 (47%) of the negative recipients. Sodium dodecylsulphate polyacrylamide gel electrophoresis and Western blotting was also performed for 68 of the recipients and antibody reactivity was detected in 22 patients compared to 26 patients exhibiting AECA detectable by microcytotoxicity. The presence of AECA demonstrable by Western blotting did not correlate with graft survival, rejection or infection. In conclusion, AECA detectable prior to single lung transplantation are associated with a decrease in graft survival and with postoperative infections.

Adult↗
PubMed1995

Elevated 8-hydroxydeoxyguanosine in hepatic DNA of rats following exposure to peroxisome proliferators: relationship to mitochondrial alterations.

Recent studies have indicated a lack of correlation between hepatic 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels and the carcinogenicity of peroxisome proliferators (PP) and suggested that DNA in intact hepatic nuclei may be insensitive to increases in 8-OHdG resulting from PP exposure. The possibility that PP-induced elevations in acyl CoA oxidase (ACO) activity might result in oxidative damage to mitochondrial DNA (mtDNA) was therefore investigated by feeding male F344 rats the hepatocarcinogenic PP Wy-14,643 (Wy, 0.1% in the diet) for 3, 6, 11, or 22 weeks, or clofibric acid (CA, 0.5% in the diet) for 22 weeks. Following the respective PP exposures, hepatic peroxisomal acyl CoA oxidase activity was determined and DNA isolated from either mitochondria or unfractionated liver homogenates and analysed for the presence of 8-OHdG. PP treatment caused an increase in ACO activity (10- to 15-fold) at all time points examined and an increase of 8-OHdG (1.5- to 2-fold) in DNA isolated from unfractionated liver homogenates following PP treatment for 11 or 22 weeks. No increase of 8-OHdG in mtDNA was detected. However, quantitation of a PCR amplified region from the D-loop of mtDNA demonstrated a 2- to 3-fold increase in the relative amount of mtDNA in DNA isolated from unfractionated liver homogenates following 3, 11, and 22 weeks exposure to Wy or CA (22 weeks only). In addition, a slight increase in the mitochondrial volume density (1.4-fold) was observed in electron micrographs of liver samples from rats exposed to Wy for 22 weeks. These results (i) demonstrate that PP treatment, at levels which cause an increase in ACO activity, does not cause oxidative damage to mtDNA, and (ii) suggest that one reason for the observed increase of 8-OHdG in DNA from unfractionated liver homogenates may be an increase in the amount of mtDNA present in these samples. Furthermore, these studies provide additional evidence against a role of oxidative DNA damage, measured as 8-OHdG, in PP-induced rodent hepatocarcinogenesis and suggest that alterations in mitochondria or other effects may be more pertinent to PP-related carcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1994

Alloproliferative responses of purified CD4+ and CD8+ T cells to endothelial cells in the absence of contaminating accessory cells.

Human capillary endothelial cells (EC), unlike rodent, constitutively express MHC class II antigens, raising the question of whether they can cause direct stimulation of resting T cells. Although previous reports have demonstrated an alloproliferative response between cultured human EC and resting T lymphocytes, they have not stringently proven the absence of contaminating leukocytes in both stimulator and responder populations. Here, we have quantitated the number of contaminating leukocytes in serially passaged human umbilical vein endothelial cells (HUVEC) and have examined the ability of HUVEC and an EC line (EAhy.926) to cause allostimulation of positively selected CD4+ and CD8+ T cells. Contaminating CD45+ leukocytes were found in primary cultures at a mean level of 0.43 +/- 0.49%; by passages 3 and 4 there were less than 1/10,000 cells. CD4+ and CD8+ T cells were purified by positive selection on antibody-coated Dynabeads and residual DR+ cells were removed by complement-dependent lysis. They were shown to be depleted of monocytes by their failure to proliferate in response to OKT3 and PHA. Nevertheless, the same cells gave an unequivocal response to cytokine-treated, serially passaged HUVEC or EAhy.926 cells. The response of CD4+ but not CD8+ T cells was dependent upon pretreatment of HUVEC or EAhy.926 with human rIFN-gamma. Neither CD4+ nor CD8+ T cells responded to MHC class II-bearing fibroblasts or epithelial cells. The CD8+ T cells that recognized EC did not respond to spleen cells in an MLR. The results confirm that EC, unlike other non-bone-marrow-derived cells, have the ability to provide all the signals necessary for direct stimulation of resting allogeneic T cells.

Antigen-Presenting Cells↗
PubMed1994

Local production of cytokines in the human cardiac allograft. A sequential study.

The observations of 2 types of CD4+ T cells (Th1 and Th2), which can be distinguished by their different cytokine profiles, has led to the possibility that analysis of cytokine profiles produced locally within transplanted allografts could be predictive of rejection or acceptance of that graft. We have investigated the expression of IL-2 and TNF beta (Th1 type cytokines), IL-4 and IL-10 (Th2 type cytokines), and the proinflammatory cytokines TNF alpha and IL-1 beta in sequential endomyocardial biopsies collected from 12 cardiac transplant recipients during the first 4 months after transplantation, by the analysis of RNA extracted from each biopsy by reverse transcriptase-polymerase chain reaction. The results obtained were compared with histopathological and clinical indicators of rejection. IL-2 was found in all severe (grade 3), in 57% of moderate (grade 2), in 21% of mild (grade 1) rejection, and in only 1 nonrejection (subsequently progressing to grade 3), where rejection was classified by routine histology. IL-4 and IL-10 were absent from grade 3 rejection, but present in 24% (IL-4) and in 17% (IL-10) of mild rejection and in a single nonrejecting biopsy, respectively. IL-4 was found in 2 cases of moderate rejection, and IL-10 in 1 case of moderate rejection. Statistical analysis showed that the presence of IL-2 positively correlated with both mild and moderate rejection, while IL-4 correlated with mild rejection (P < or = 0.05). IL-1 beta, TNF alpha, and TNF beta were found in both rejecting and nonrejecting biopsies, with no significant differences between the histological grades. Our results suggest that in the human situation, IL-2 and IL-4 may indeed be important in the modulation of rejection.

Base Sequence↗
PubMed1994

Increased cyclosporine sensitivity of T cells from cord blood compared with those from the adult.

Despite the increasing numbers of paediatric transplants performed, little is known about the immune responses of T lymphocytes in human neonates. Here we have compared the effects of cyclosporine on the phytohaemagglutinin (PHA) response of immature (cord) and mature (adult) lymphocytes using the following parameters of activation: (i) proliferation, measured by 3H-thymidine uptake; (ii) expression of cell surface IL-2 receptor; (iii) release of IL-2 into the supernatant. Cyclosporine was added to cultures of PHA-stimulated lymphocytes at doses ranging from 5 to 5000 ng/ml. The proliferative response of cord lymphocytes was considerably more sensitive to cyclosporine at each dose, so that 50% inhibition was achieved by 6 ng/ml and 21.5 ng/ml doses of cyclosporine on cord and adult lymphocytes, respectively. Expression of the IL-2 receptor by PHA-activated T cells and their subsets was assessed by flow cytometry. Cyclosporine inhibited IL-2 receptor expression to a significantly greater degree in cord CD4 and CD8 cells (49.7% and 70.1%) than in adults (17.9% and 30.0%). Biologically active IL-2 release was measured using the IL-2-dependent cell line CTLL-2. Cyclosporine at doses 50-5000 ng/ml produced 80-99% inhibition of both cord and adult responses. However, at very low doses (5 ng/ml) cyclosporine produced 69.3% inhibition of cord lymphocytes, compared with 42.0% of adult lymphocytes. These results suggest that the T cells of neonates are considerably more sensitive to cyclosporine than are adult T cells.

Adult↗
PubMed1994

Complement-mediated cytotoxic activity of anti-heart antibodies present in the sera of patients with dilated cardiomyopathy.

A microcytotoxicity assay has been used to determine the cytotoxic activity of anti-heart antibodies which we have previously shown to be present with greater frequencies and reactivities in patients with dilated cardiomyopathy (DCM) than in patients with ischaemic heart disease (IHD). Serum samples from 45 patients with DCM and 43 patients with IHD were screened against W1, a transformed human fetal cardiac cell line and also against EA.hy 926, an endothelial and IBR3, a fibroblast cell line. In the presence of complement, sera from 28 (62%) DCM patients showed killing of the W1 cell line as compared to sera from 13 (30%) of IHD patients (p < 0.005) and 3 (15%) of normal individuals. In contrast, only 1 patient with DCM showed killing of the endothelial cell line and 1 patient with IHD showed killing of the fibroblast cell line. These results provide evidence for a complement-dependent, antibody-mediated mechanism of damage to cardiac myocytes which may contribute to the pathogenesis of DCM.

Adolescent↗
PubMed1993

Frequency and specificity of antiheart antibodies in patients with dilated cardiomyopathy detected using SDS-PAGE and western blotting.

OBJECTIVES: This study was designed to investigate the organ and disease specificity of antiheart antibodies in patients with dilated cardiomyopathy. BACKGROUND: Autoimmune disease is characterized by the presence of circulating autoantibodies, and autoimmune mechanisms may play a role in the pathogenesis of dilated cardiomyopathy. METHODS: An SDS-PAGE (sodium dodecylsulfate polyacrylamide gel electrophoresis) procedure followed by Western blotting was used to screen serum samples for antiheart antibodies of two immunoglobulin classes, IgM and IgG, from 52 patients with dilated cardiomyopathy and 48 patients with ischemic heart disease as control subjects. Use of two-dimensional gel electrophoresis followed by Western blotting and protein sequencing enabled us to identify the protein bands against which antiheart antibodies were produced in both groups of patients. RESULTS: Strong IgG antiheart antibodies against myocardial proteins, cross-reacting with skeletal muscle proteins, were detected in significantly more patients with dilated cardiomyopathy (n = 24 [46%]) than with ischemic heart disease (n = 8 [17%]) (p = 0.001). Patients with dilated cardiomyopathy showed a significantly greater frequency and reactivity of IgG antiheart antibodies against six myocardial proteins (molecular weight 30, 35, 40, 60, 85 and 200 kD) than did patients with ischemic heart disease. These were identified as myosin light chain 1, tropomyosin, actin, heat shock protein (HSP)-60, an unidentified protein and myosin heavy chain, respectively. CONCLUSIONS: We detected strong IgG antiheart antibodies in significantly more patients with dilated cardiomyopathy than with ischemic heart disease. The most immunogenic band was that corresponding to HSP-60. Antibodies against HSP-60 were found in 85% and 42% of patients with dilated cardiomyopathy and ischemic heart disease, respectively, confirming our hypothesis of an immune involvement in dilated cardiomyopathy.

Actins↗
PubMed1993

Coronary artery immunogenicity: a comparison between explanted recipient or donor hearts and transplanted hearts.

Transplant associated accelerated coronary sclerosis (TX-ACS) is the most serious complication following heart transplantation. In order to elucidate the involvement of possible immune mechanisms, we have used immunocytochemistry to characterize the antigens present on the endothelium and the cells present within coronary arteries taken at time of surgery from patients who required retransplantation (n = 4) or at post mortem (n = 10) from transplant patients who died. Coronary arteries from unused donor hearts (n = 4) or heart transplant recipients whose original disease did not involve the coronaries (n = 8) were used as controls. Endothelium from all control coronary arteries strongly expressed MHC class I, DR antigen, PECAM, ICAM-1 and E-selectin. Expression of VCAM-1, DP and particularly DQ antigen was more patchy. There was no significant difference in the expression of MHC or adhesion molecules between control arteries and those from transplant patients. More cells were present in the intima and media of coronary arteries taken from transplanted hearts, particularly those with intimitis/TX-ACS, than were found in control coronaries. T cells were present in the intima of most coronaries, but the media of only the transplanted coronaries. Cells expressing prolyl 4-hydroxylase were more evident on coronaries from transplanted hearts. In conclusion, coronary arteries from hearts used for transplants appear to be highly immunogenic. This suggests the endothelium would need little, if any, stimuli to initiate as well as be a target for an immune response after transplantation.

Animals↗
PubMed1993

The effect of panel reactive antibodies and the donor specific crossmatch on graft survival after heart and heart-lung transplantation.

Data from 699 cardiac and 290 heart-lung transplants has been analysed to determine the importance of the lymphocytotoxic crossmatch result and panel reactive antibody (PRA) status on graft survival. Donor reactive crossmatching was performed for 636 cardiac transplants. One year actuarial survival for a negative crossmatch (n = 580) was 73% compared to 56% for the positive crossmatch recipients (n = 56) p = 0.0014. Where crossmatches were performed on separated T and B cells, the T cell directed crossmatch was found to be highly predictive of graft failure in 289 cardiac transplants. One year survival for a negative crossmatch was 73% (n = 258), for B cell positive crossmatch recipients 62% (n = 24), and for a positive T cell crossmatch 28% (n = 7) (p = 0.001). Patients' PRA status were grouped into those with negative, medium and high frequencies. There was a trend (not statistically significant) for patients with PRA above 50% to have poor graft survival. Patients with PRA above 50% were significantly more likely to have a positive lymphocytotoxic crossmatch against donor lymphocytes. Donor reactive crossmatching was performed for 283 heart-lung transplants. One year actuarial survival for a negative crossmatch was 61% (n = 251) and for a positive result was 50% (n = 32), p = 0.02.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody Specificity↗
PubMed1993

Effect of endotoxin on tirilazad mesylate (U74006F) pharmacokinetic parameters in neonatal calves.

The pharmacokinetics of the 21-aminosteroid tirilazad mesylate (U74006F) were studied in both healthy and endotoxin-challenged neonatal calves. Group I calves received a 3-h intravenous (i.v.) infusion of sterile saline (250 ml) and tirilazad mesylate (1.5 mg/kg i.v.) 1 h after the start of the saline infusion. Group II calves received tirilazad mesylate 1 h after the start of a 3-h endotoxin (3.25 micrograms/kg) infusion. The data obtained indicate that tirilazad mesylate follows a biexponential equation in neonatal calves. The area-derived volume of distribution (Vdarea) was 9.68 +/- 0.759 l/kg in healthy calves and 6.53 +/- 1.20 l/kg in endotoxin-challenged calves (P < 0.05). Similarly, significant (P < 0.05) decreases in steady-state volume of distribution (Vdss) and central volume (Vc) were observed in endotoxin-challenged calves (5.32 +/- 0.979 l/kg and 1.68 +/- 0.189 l/kg, respectively) compared to healthy calves (7.58 +/- 0.834 l/kg and 2.43 +/- 0.452 l/kg, respectively). A and B were significantly larger in endotoxin-challenged calves than in healthy calves (P < 0.05). Rate constants and their associated half-lives, area under the curve and clearance were not significantly altered by endotoxin challenge. Serum thromboxane generation (ex vivo) was evaluated as a marker of the drug's physiologic activity. There was no significant difference in thromboxane generation during clotting of blood from healthy and endotoxemic calves treated with tirilazad mesylate.

Animals↗