Mary M. Meyer

T-cell receptor variable β genes show differential expression in CD4 and CD8 T cells

Abstract Studies in transgenic and inbred strains of mice have shown that the critical molecular interactions controlling positive selection involve major histocompatibility complex (MHC), T-cell receptor (TCR), and CD4 or CD8 coreceptor molecules. Correlations have been established between MHC gene products and the percentage of CD4 or CD8 T cells that express specific variable (V) β-gene products as part of the αβ heterodimer. These studies have important implications regarding potential mechanisms of HLA-linked autoimmune diseases in humans. If similar interactions are required for positive selection in humans, one would predict that the TCR repertoire expressed by mature, peripheral blood CD4 and CD8 T cells would vary. To test this hypothesis the expression of specific TCR Vβ-region genes by CD4 and CD8 T cells from healthy individuals was compared using both triple-color flow cytometry and polymerase chain reaction based experimental approaches. The results show that the TCR repertoire does vary as a function of CD4 and CD8 T-cell subsets. Among unrelated individuals certain Vβ genes were consistently overrepresented in the CD4 population (Vβ-5.1, −6.7a, and −18); some were skewed to the CD8 population (Vβ-14) while others showed variable patterns (Vβ-12 and −17). Deletion of entire Vβ gene families was not observed suggesting that this is a rare event in humans. Attempts to correlate the expressed TCR repertoire in humans with HLA alleles will require consideration of these differences in expression as a function of subset.

Chinese herb nephropathy.

In 1994, a 44-year-old woman progressed from normal renal function to advanced renal failure and end-stage renal disease within 8 months. Biopsy revealed extensive interstitial fibrosis with focal lymphocytic infiltration. She received a cadaveric renal transplant in January 1996 and had an uneventful posttransplant course. As a result of a minor motor vehicle accident, the patient had received acupuncture and Chinese herbal medicine for pain relief approximately 5 months before the onset of renal symptoms. After the transplant, analysis of the herbal remedies clearly indicated the presence of aristolochic acid in 2 of the 6 Chinese herbs ingested. Ingestion of aristolochic acid has been linked to a newly defined entity, Chinese herb nephropathy (CHN). This article discusses the history of CHN and its implication in the current case and in other recent similar cases and makes recommendations to avoid future problems caused by unregulated use of herbal medicines. This is the first reported case of CHN in the USA.

N-Acetylcysteine for patients with prolonged hypotension as prophylaxis for acute renal failure (NEPHRON)

Background:Acute renal failure is a common complication in critically ill patients and carries an increased morbidity and mortality. N-acetylcysteine is an antioxidant and anti-inflammatory agent that may counteract some of the pathophysiologic derangements in shock states. Objective:To test whether the administration of N-acetylcysteine, compared with placebo, reduces the incidence of acute renal failure in hypotensive patients. Design:Prospective, randomized, double-blinded, placebo-controlled study. Setting:Intensive care units of a university tertiary care hospital. Patients:One hundred forty-two patients with new onset (within 12 hrs) of at least ≥30 consecutive minutes of hypotension and/or vasopressor requirement. Interventions:Patients were randomized to receive either N-acetylcysteine or placebo for 7 days, in addition to standard supportive therapy. Measurements and Main Results:Patients who received N-acetylcysteine had an incidence of acute renal failure (≥0.5 mg/dL increase in creatinine) of 15.5%, compared with 16.9% in those receiving placebo (p = .82, not significant). There were no significant differences between treatment arms in any of the secondary outcomes examined, including incidence of a 50% increase in creatinine, maximal rise in creatinine, recovery of renal function, length of intensive care unit and hospital stay, requirement for renal replacement therapy, and mortality. Among patients receiving N-acetylcysteine, there were trends toward reduced incidence of acute renal failure in patients with baseline Sequential Organ Failure Assessment (SOFA) score >8 (p = .12), lower SOFA scores during the first 4 days of treatment (p = .28), and reduced mortality in patients <65 yrs of age (p = .20). Conclusions:There were no significant differences in any of our primary or secondary end points between patients treated with N-acetylcysteine or placebo. Trends toward reduced incidence of acute renal failure in patients with baseline SOFA score >8, reduced SOFA scores during the first 4 days, and reduced mortality in patients <65 yrs of age are provocative but require further study to determine their clinical significance.

Interaction Between Cyclosporine and Grapefruit Juice Requires Long‐Term Ingestion in Stable Renal Transplant Recipients

Study Objective. To examine the effect of the concurrent administration of increasing amounts of grapefruit juice, an inhibitor of drug metabolism, on the steady‐state pharmacokinetics of cyclosporine.

Meropenem pharmacokinetics in a patient with multiorgan failure from meningococcemia undergoing continuous venovenous hemodiafiltration

Meropenem is a carbapenem antibiotic with a broad antibacterial spectrum of activity. Its main route of elimination is through the kidneys, with 63% of the drug excreted unchanged in the urine. Meropenem clearance is diminished in renal impairment; therefore, doses need to be adjusted in patients with varying degrees of renal function. An appropriate dose of meropenem for patients undergoing continuous venovenous hemodiafiltration (CVVHDF) is unknown. We evaluated the pharmacokinetics of meropenem in a patient with fulminant meningococcemia undergoing CVVHDF. Meropenem concentrations in serial venous, arterial, and ultrafiltrate samples after a 1 g intravenous dose were measured using high-performance liquid chromatography (HPLC). Meropenem clearance was found to be 129.36 mL/min and 141.29 mL/min for every 8- and 12-hour dosing, respectively. Trough levels were above the MIC90 for Neisseria meningitidis and most anaerobic pathogens. We recommend that meropenem 1 g intravenously every 12 hours be used as the initial dose in patients undergoing CVVHDF. Differences between meropenem clearance during CVVHDF and other forms of renal replacement therapy are discussed.

A prospective, double-blind, randomized study of high-versus low-dose OKT3 induction immunosuppression in cadaveric renal transplantation.

We undertook a prospective, double-blind study of high-(5-mg) versus low-(2-mg) dose OKT3 for induction immunosuppression (12 days) in cadaveric renal allograft transplantation. Maintenance immunosuppression was identical in both groups and consisted of azathioprine and prednisone initially, with cyclosporine beginning on the 5th postoperative day. Twenty-six patients were randomized. The groups were similar in terms of age, kidney ischemia time, peak PRA, and latest PRA. There were more diabetics and women in the high-dose group. Patient survival at 12 months was 100% in both groups. Graft survival at 12 months was 92% and 100% in the high- and low-dose groups, respectively. Infections were mostly minior and equal in frequency in the two groups. All patients receiving high- or low-dose OKT3 had manifestations of the cytokine release syndrome; these were delayed in onset in the low-dose group. Eleven patients (85%) in each group produced anti-OKT3 andtibodies. Lymphocyte depletion after 1 day was major (>98%) and identical in both groups. CD3 antigens were removed more slowly in the low-dose group but eventually at equal rates in both groups. Cost was significantly lower in the low-dose group. We conclude that while both doses of OKT3 were effective and safe for induction immunosuppression, it may be prudent to use a lower dose of OKT3 for induction immunosuppression because of its potential to reduce cytokine-mediated effects and to avoid the complications of overimmunosuppression and because of the lower costs associated with it.

Cadaver kidney transplantation in patients more than 65 years old

SummaryElderly patients with end-stage renal disease often remain on dialytic therapy because they are at increased risk for mortality and morbidity. We placed 24 cadaver kidney transplants into 24 patients aged 65–74 years between September 1, 1985, and August 31, 1995. Rates of patient and graft survival were compared with those of 404 concurrent first cadaver-kidney transplant recipients between the ages of 20 and 44 years. The 5-year rates of patient and graft survival were not significantly different (86% versus 92% and 77% versus 63%, respectively; study group presented first). Primary cadaver kidney transplantation can be successfully performed in patients older than 65 years when a selection algorithm is applied to exclude active infection, active malignancy, unsuitable anatomy for technical success, high probability of operative mortality, and noncompliance. Pelvic arteriosclerosis and lower urinary tract abnormalities can cause intraoperative technical problems.

Nitrofurantoin-induced pulmonary hemorrhage in a renal transplant recipient receiving immunosuppressive therapy : case report and review of the literature

A 33-year-old woman received a cadaveric renal transplant for focal segmental glomerulosclerosis. Nitrofurantoin urinary prophylaxis was started on postoperative day 13 but coughing and mild hemoptysis began 2 days later. Diffuse infiltrates and worsening hemoptysis led to intubation and open lung biopsy. Clinical course, culture results and pathological evaluation excluded infectious etiologies and were consistent with a drug reaction. The case is described, and the literature on the nitrofurantoin pulmonary toxicity syndromes and pathophysiology is reviewed.

Cyclosporine and Vancomycin Disposition During Continuous Venovenous Hemodiafiltration

Objective: To report cyclosporine and vancomycin disposition during continuous venovenous hemodiafiltration (CVVHD) in a 41—year-old heart transplant patient while in the intensive care unit at a primary and tertiary care teaching hospital. Case Summary: The patient received a 60—mg infusion of cyclosporine over 24 hours and vancomycin 1 g over 1 hour. Blood samples subsequently were collected and analyzed using whole blood monoclonal radioimmunoassay and fluorescence polarization immunoassay, respectively. Blood samples were measured every hour from the arterial and venous lines of the apparatus, as were ultrafiltrate drug concentrations. Drug clearance rates into the ultrafiltrate subsequently were calculated. Discussion: Measurements of ultrafiltrate detected no cyclosporine. A slight variation existed between arterial and venous drug concentrations, which was not statistically significant (p > 0.05, paired Students t-test). Analysis of vancomycin samples revealed a steady decline of drug concentration, with 4.75% of the dose eliminated in the ultrafiltrate. Vancomycin arterial and venous concentrations decreased from 24.4 and 23.3 mg/L to 15.7 and 12.3 mg/L, respectively. Conclusions: Vancomycin is eliminated by CVVHD and it may be necessary for these patients to receive the drug more frequently. In contrast, cyclosporine is not removed effectively by CVVHD; therefore, replacement doses are not warranted.

Interleukin-12 p40 m-RNA expression in human kidney allograft biopsies

Interleukin-12 (IL-12) is a heterodimeric cytokine implicated in the early differentiation of naive T-lymphocytes into the Th1 subset. IL-12 is important for induction of the cellular immune response against viruses, intracellular parasites and neoplasms. Its role in alloresponsiveness has not been fully elucidated. Preliminary data in the literature point toward the prevalence of Th1 lymphocytes in processes of allograft rejection. In attempt to further investigate the expression of this cytokine during episodes of cellular rejection of renal allografts, we searched for IL-12 message in human kidney allograft biopsies using the reverse transcriptase-polymerase chain reaction technique. Twenty-three allograft core biopsies from 19 patients were obtained percutaneously for clinical indications in 18 cases, and as part of an investigational protocol in five cases. A portion of the tissue was used for RNA extraction using the guanidium-thiocyanide phenol-chloroform method. Histology was performed on the remaining core material. Ten mg of total RNA were used for reverse transcription. PCR of the c-DNAs was done for 40 cycles using primers for the p40 subunit of IL-12 and GAPDH which was used as a control. PCR products were photographed after electrophoresis, transferred to a nylon membrane and hybridized with a radiolabelled cloned human IL-12 p40 1 kb c-DNA fragment. Autoradiographies were developed after 20-min exposure. All samples were run in triplicate. IL-12 p40 m-RNA was expressed in all 17 biopsies showing acute cellular rejection as well as in all three biopsies showing focal interstitial fibrosis. No message was found in the presence of normal allograft histology. This is the first in vivo report of IL-12 p40 subunit m-RNA expression during renal allograft rejection in humans. The role of this Th1 cytokine in the alloresponse deserves further investigation.