Search PubMed⌕ Search

Biomedical subjects

K L Cox

Publications and source records attributed to K L Cox.

At least 37 records · Page 2Linked to original sources
PubMed1997

Epstein-Barr virus lymphoproliferative disorders after liver transplantation.

Post-transplant lymphoproliferative disorders (PTLD) represent a spectrum of histological and immunological abnormalities, ranging from benign polyclonal B-cell hyperplasia to monoclonal malignant lymphoma. The important role of Epstein-Barr virus (EBV) in PTLD in liver transplant patients, particularly in pediatric recipients, is reviewed. Understanding the risks of EBV infection, the clinical presentations and diagnosis of PTLD, and its pathophysiology are crucial to the management of these disorders. Current treatment methods have resulted in better outcomes of these disorders, which in the past were uniformly fatal.

Adult↗
PubMed1996

Suppression of murine chronic relapsing experimental autoimmune encephalomyelitis by the oral administration of myelin basic protein.

Chronic relapsing experimental autoimmune encephalomyelitis (EAE), induced in mice by the injection of myelin basic protein (MBP), is a T cell-mediated autoimmune disease characterized by periods of paralysis and remission. We have shown previously that the oral administration of MBP or MBP peptides renders Lewis rats refractory to EAE. This study was undertaken to examine the conditions necessary to produce oral tolerance in a chronic relapsing model of EAE in B10.PL mice. The optimal tolerizing regimen for the mouse was found to be a single feeding of 20 mg of MBP suspended in PBS. To determine the ability to suppress chronic disease, a range of doses (0.4-100 mg) was administered orally in a single dose before challenge. Larger oral doses (20 or 100 mg) of MBP provided the best protection from EAE, while 0.4 mg exacerbated the clinical course of disease. Secretion of the proinflammatory cytokines, IL-2 and IFN-gamma, were lowest in the group fed 20 mg. A single feeding of MBP before challenge or as late as the first day of clinical signs showed significant protection over the relapsing disease course. Once relapsing EAE was established, multiple oral doses of MBP were required to achieve suppression of clinical signs of disease. These findings suggest that vehicle, dosage, and timing are important considerations in the successful application of oral tolerance strategies for suppression of chronic disease processes.

Administration, Oral↗
PubMed1996

Continuous venovenous hemofiltration with dialysis in combination with total hepatectomy and portocaval shunting. Bridge to liver transplantation.

Children who experience acute liver failure following liver transplantation will have multiple organ failure and a high rate of mortality unless emergency retransplantation can be performed. Transplant hepatectomy with portocaval shunting has been described as a bridge to transplantation in the most severe cases, as well as in patients with fulminant hepatic failure at high risk for mortality who have not undergone liver transplantation. Patients with multiple organ failure who have undergone hepatectomy require renal replacement therapy. Continuous hemofiltration may be used in patients with fulminant hepatic failure to facilitate fluid removal and circulatory and metabolic balance. We used continuous venovenous hemofiltration with dialysis following hepatectomy with portocaval shunting in a patient who remained anhepatic for 66 hr in order to achieve circulatory and metabolic homeostasis as well as stable neurologic function prior to successful retransplantation.

Child, Preschool↗
PubMed1996

Oral tacrolimus (FK506) induction therapy in pediatric orthotopic liver transplantation.

We have adopted the use of an oral tacrolimus induction protocol in pediatric liver transplantation since the commercial release of tacrolimus in 1994. In this study we analyzed the efficacy of oral tacrolimus induction therapy in 17 consecutive transplants (15 patients) performed between 6/94 and 2/95 and 4 additional patients who were retransplanted between 11/93-5/94 and received compassionate oral tacrolimus induction. Sixteen transplants were treated with oral tacrolimus induction only; 5 transplants, oral tacrolimus + ATGAM/OKT3 induction. The protocol consisted of 0.2 mg/kg of tacrolimus orally on the first postoperative day with a corticosteroid taper. Oral tacrolimus was started at day 1-8 in the 5 patients receiving ATGAM/OKT3 induction. Dosages were adjusted over time to maintain a whole-blood trough level of 12-15 ng/ml at 0-1 month, 10-12 ng/ml at 1-3 months, and 5-10 ng/ml after 3 months. The incidence of acute rejection was 50% (8/16) in children on oral tacrolimus induction alone and 80% (4/5) in the tacrolimus + ATGAM/OKT3 group. Epstein-Barr virus infection occurred in 6 of 19 children (32%), with no child developing lymphoproliferative disorder. No adverse effect on renal function was noted. Serum fasting glucose was stable over time while a trend was noted in decreasing serum cholesterol levels at 6 months. Antihypertensive medication was required in 4 of 19 children (21%) posttransplantation. Corticosteroids were withdrawn in 11% (2/19) of patients. Actuarial 1-year patient and graft survivals were 95% and 86%, respectively. The use of oral tacrolimus induction therapy was associated with excellent survival and a low incidence of complications.

Administration, Oral↗
PubMed1996

Oral tolerance in experimental autoimmune encephalomyelitis.

In work performed by a number of laboratories, it has become quite clear that the oral administration of autoantigens exerts a profoundly suppressive effect on the development and long-term clinical course of autoimmune disease. Specific peptide sequences derived from the autoantigens are similarly suppressive. An interesting sidelight to emerge from specificity studies is that oral administration of a self-protein or peptide sequence (i.e., rat MBP peptide administered to a rat) is markedly less tolerogenic than oral administration of a non-self or even closely related sequence (guinea pig MBP peptide administered to a rat). The dose of oral antigen is now known to play a critical role in determination of the mechanism of oral tolerance, with low doses of antigen causing active suppression with concomitant release of TGFbeta1. Studies outlined here suggest that oral administration of higher antigen doses (e.g., 20 mg MBP to rats or mice) results in deletion of specific antigen-reactive T lymphocytes. This conclusion stems from the fact that injections of IL-2 could not reverse high-dose tolerance while reversing low-dose oral tolerance. Moreover, feeding MBP to MBP-TCR transgenic mice caused trafficking of transgenic cells to the intestine followed by a profound depletion of transgene-positive cells and reduction in proliferative function in all peripheral lymphoid organs. Oral tolerance has proven to be of therapeutic benefit in other animal models of autoimmune disease as well, including uveitis, collagen-induced arthritis, adjuvant arthritis, thyroiditis, myasthenia gravis, and diabetes. Initial human trials in multiple sclerosis, rheumatoid arthritis, and uveitis show promising results.

Administration, Oral↗
PubMed1996

Treatment of autoimmune disease by oral tolerance to autoantigens.

Multiple sclerosis (MS) is a chronic demyelinating disease of the human central nervous system (CNS) which can be characterized clinically by a remitting-relapsing or a chronic progressive course. There is a striking similarity between the clinical and histopathological features of MS and the experimentally induced disease, experimental autoimmune encephalomyelitis (EAE). Induced by the injection of myelin basic protein (MBP) and adjuvants, EAE is characterized by clinical neurologic signs of paralysis and histopathologic changes consisting of perivascular mononuclear infiltration and demyelination. We have reported that the oral administration of MBP exerts a profoundly suppressive effect on EAE induced in the Lewis rat. This MBP-induced oral tolerance is characterized by an inhibition of EAE clinical neurologic signs, reduced CNS histopathologic changes, a profound decrease in the T-lymphocyte proliferative response specific for the fed antigen, and a decrease in serum antibody specific for MBP. In a chronic relapsing model of EAE in the B10.PL mouse, we have shown that the oral administration of MBP either prior to MBP challenge or on the first day of clinical signs results in a decreased number and severity of EAE relapses. The oral tolerance approach has also proven effective in the suppression of other organ-specific autoimmune diseases including collagen-induced arthritis, adjuvant arthritis, uveoretinitis, experimental myasthenia gravis, diabetes, and thyroiditis as well as graft rejection. Two primary mechanisms have been proposed to explain oral tolerance in EAE-active suppression following feeding of lower doses of antigen and clonal anergy or deletion following administration of higher doses. In vivo approaches in rats and transgenic mice have been used to further explore the mechanisms underlying oral tolerance. Administration of recombinant interleukin (IL)-2 was shown to reverse the tolerance induced by feeding low doses of MBP, but not the tolerance induced by feeding high doses of MBP, indicating that deletion had occurred in the high-dose group. Moreover, the oral administration of MBP to MBP-specific T-cell receptor (TCR) transgenic mice resulted in a profound decrease of the transgenic T cells in the blood, lymph node cells (LNC), mesenteric LNC, and spleen compartments. The proliferative response to MBP was also profoundly reduced in these organs, indicating that the cells had been deleted from these sites. The results achieved in animal models have led to clinical trials of oral tolerization in three human autoimmune diseases--MS, uveoretinitis, and rheumatoid arthritis--with promising results.

Administration, Oral↗
PubMed1996

Exercise and weight control in sedentary overweight men: effects on clinic and ambulatory blood pressure.

OBJECTIVE: To examine whether restriction of caloric intake and exercise of vigorous intensity can independently and additively influence clinic and ambulatory blood pressures in sedentary overweight men. DESIGN: Sixty subjects aged 20-50 years were randomly allocated either to continue their normal caloric intake or to restrict it by 4186-6279 kl/day, with 15% provided by protein, 30% by fat and 55% by carbohydrate, for 16 weeks. Within each of these groups subjects were further randomly allocated either to a control light intensity programme of exercise or to a vigorous intensity programme of exercise for 30 min three times a week. The light exercise group performed stationary cycling against no resistance, flexibility exercises and slow walking. The vigorous intensity group cycled on an ergometer at 60-70% of maximum their workload. RESULTS: Fifty-one subjects completed the study. Their maximal oxygen uptake was increased by approximately 24% with vigorous exercise but did not change with light exercise. Caloric intake restriction led to a significant loss of body mass of 9.5 kg (95% confidence interval 7.6-11.3), whereas vigorous exercise had no effect. Restriction of caloric intake reduced supine clinic systolic and diastolic blood pressures significantly by 5.6 (2.3-8.9) and 2.4 mmHg (0.4-4.2), respectively. Relative to the control light exercise group, exercise of vigorous intensity exercise had no significant effect on clinic blood pressure. In contrast, time series analysis revealed that both caloric intake restriction and vigorous exercise were associated with lower daytime ambulatory systolic blood pressure, the reduction in systolic blood pressure being sustained throughout the 24 h period when vigorous exercise and caloric intake restriction were combined. CONCLUSION: Compared with the effects of caloric intake restriction, the effects of a vigorous exercise programme on blood pressure are inconsistent, there being no influence on clinic blood pressure but a reduction in daytime ambulatory blood pressure. However, when combined with caloric intake restriction, regular vigorous exercise exhibits a synergistic effect in reducing ambulatory blood pressure throughout a 24 h period.

Adult↗
PubMed1996

Tacrolimus (FK506): the pros and cons of its use as an immunosuppressant in pediatric liver transplantation.

Tacrolimus (FK506) is a new immunosuppressive agent that has recently been given to recipients of liver transplants. Multicentre studies conducted in the United States and Europe have reported that tacrolimus is superior to cyclosporine in preventing allograft rejection. The absorption of tacrolimus is independent of bile, and, therefore, therapeutic blood levels are usually achieved by taking oral preparations within 72 hours of liver transplantation. Compared with the use of cyclosporine, this regimen has resulted in shorter hospital stays and reduced costs. Tacrolimus does not cause hirsutism or gingival hyperplasia, which are common disfiguring complications of cyclosporine. Serious neurological side effects, lymphoproliferative disorders and hypertrophic cardiomyopathy have recently been reported in children taking high doses of tacrolimus. When lower doses of tacrolimus are used in primary immunosuppressive therapy, the incidence of neurological side effects and lymphoproliferative disorders of tacrolimus and cyclosporine have been reported to be similar. Hence, tacrolimus is a potent immunosuppressant that has many advantages over cyclosporine but must be used cautiously, since high doses have been associated with an increased incidence of lymphoproliferative disorders and cardiomyopathy.

Child↗
PubMed1995

Exquisite peptide specificity of oral tolerance in experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE), induced in Lewis rats by injection of myelin basic protein (MBP) and adjuvant, is a T cell-mediated autoimmune disease. Earlier studies from our laboratory have shown that oral administration of guinea pig MBP before encephalitogenic challenge induces T cell anergy and results in the suppression of clinical signs and CNS histopathologic changes of EAE. In contrast, oral administration of rat MBP did not confer a similar degree of protection. This study was undertaken to determine the tolerogenicity of the synthetic peptide 68-88 derived from guinea pig (GP) MBP and rat MBP. These peptides differ by a single amino acid at position 80. Lewis rats fed GP 68-88 were protected from EAE induced with GP 68-88 or rat 68-88. In contrast, feeding rats 68-88 did not protect the animals from challenge with either peptide. Measurement of the frequency of peptide-reactive Th1 cells showed results consistent with the clinical picture. The in vitro proliferative response was significantly suppressed following oral administration of either whole GP MBP, the GP peptide, or the rat peptide, irrespective of clinical status. These results extend our earlier observation at the whole molecule level that GP but not rat MBP confers oral tolerance. These findings suggest that small structural differences at the amino acid level can produce dramatic differences in clinical outcome, with important implications for the design of multiple sclerosis clinical trials.

Administration, Oral↗
PubMed1995

An increased incidence of Epstein-Barr virus infection and lymphoproliferative disorder in young children on FK506 after liver transplantation.

The incidence of Epstein-Barr virus (EBV) infection and lymphoproliferative disorder (LPD) was determined in a pediatric liver transplant population consisting of 51 children treated with FK506 and 91 treated with cyclosporine. The incidence of symptomatic EBV infection was 21.9% (23 of 105 cases) in children < 5 yr old and 10.8% (4 of 37 cases) in children 5 to 17 yr old as compared with 2.7% (9 of 323 cases) in adults (P < 0.0001). In the under 5 yr old group on cyclosporine, the incidences of EBV infection and LPD were 9 of 68 (13.2%) and 2 of 68 children, (2.9%), respectively. In contrast, in children under 5 yr old group on FK506, the incidences of EBV infection and LPD in the FK506 group were 14 of 37 (37.8%) and 7 of 37 children (18.9%), respectively. The difference between these two groups was statistically significant (P < 0.02). There were no cases of LPD in the 5-17 yr-old children on either cyclosporine (n = 23) or FK506 (n = 14). The incidence of EBV infections in the 5 to 17 yr age group, 17.4% on cyclosporine and 0% on FK506, was less than for the younger children on FK506 (37.8%). A total of 39% (9 of 23) of children under 5 yr old who had symptomatic EBV infections developed LPD, and 44% (4 of 9) with LPD died. The higher incidence of EBV infections and LPD in the younger children treated with FK506 was probably related to a greater intensity of immunosuppression for patients on FK506 than those on cyclosporine.

Adolescent↗
PubMed1995

Plasma fluorescein binding and transcapillary fluorescein escape rate in renal failure associated with diabetes.

Microvascular damage, often resulting in renal failure, is a common complication of diabetes. Transcapillary fluorescein escape rate (TCFER) as monitored by intravital microscopy has been used as an indicator of the extent of capillary damage in diabetes and to assess improvement in microvascular function after combined kidney-pancreas transplant. However, fluorescein anion binds to plasma albumin, and albumin-ligand binding may be altered in the presence of renal disease. The purpose of this study was to compare fluorescein binding by plasma from diabetics with renal failure with plasma from healthy nondiabetics. Fluorescein binding by plasma from seven type I diabetics awaiting kidney-pancreas transplant and seven healthy adults of similar age and sex was studied using ultrafiltration and dialysis. There was no significant difference in the apparent albumin binding of fluorescein at physiologically relevant fluorescein concentrations, even though the TCFER was significantly increased in the diabetics as compared with the controls. Hippurate, a ligand that accumulates in renal failure, did alter fluorescein binding in a defatted albumin solution but not sufficiently to account for the differences in TCFERs. These data indicate that impaired albumin binding of fluorescein does not contribute significantly to the TCFER in diabetics with renal failure.

Adult↗
PubMed1995

Elevated biliary interleukin 5 as an indicator of liver allograft rejection.

Interleukin 5 (IL-5) is a T cell-derived cytokine that acts as a potent and specific eosinophil differentiation factor in humans. During liver allograft rejection, intragraft IL-5 mRNA and eosinophilia have been observed. The objective of this study was to correlate the levels of IL-5 in bile and serum with eosinophilia and allograft rejection in paediatric liver recipients. IL-5 levels were determined by ELISA (enzyme-linked immunosorbent assay) in bile (n = 85) and serum (n = 106) and obtained prospectively from 15 patients during the first 3 weeks post-transplantation. Biliary and serum IL-5 levels were significantly elevated during allograft rejection compared to IL-5 levels when no rejection was apparent or during infectious complications. The highest IL-5 levels were measured in the bile during the early rejection period (3 days prior to biopsy-proven rejection). Fifteen of 16 rejection episodes were marked by increases in IL-5 as revealed by analysis of sequential samples from individual patients. In all patients with rejection, elevations in serum IL-5 were associated with elevations in peripheral eosinophil counts. These results indicate that IL-5 is produced in the liver and may be a useful and specific marker of allograft rejection. Furthermore, these findings provide further evidence for a pathway of liver allograft rejection mediated by IL-5 activated eosinophils.

Adolescent↗