Search PubMed⌕ Search

Biomedical subjects

M R First

Publications and source records attributed to M R First.

At least 163 records · Page 9Linked to original sources
PubMed1989

An evaluation of the cyclosporine and metabolites whole blood TDx assay.

The new Abbott TDx cyclosporine and metabolites fluorescent polarization immunoassay procedure provides a 20-min sample turn-around time, using 50 microliters of sample for the analysis of cyclosporine in whole blood. A precipitation agent and a lysing agent are utilized as a pretreatment step. The range of the whole blood assay is from 0 to 2,000 ng/ml, with a sensitivity of 50 ng/ml. Precision studies at 3 control levels provided coefficients of variation of 2.1-4.8% for both assays. In order to compare this assay with the currently used Sandoz polyclonal radioimmunoassay (RIA) method. 200 whole blood samples were obtained from 20 renal, cardiac, and hepatic transplant recipients. The mean whole blood cyclosporine concentrations for samples above the sensitivity level were as follows: TDx 754 ng/ml (+/- 31) and RIA 619 ng/ml (+/- 22). Blood TDx levels correlated strongly with RIA levels, with a regression coefficient of r = 0.915. This new assay provides reliable blood cyclosporine concentrations that correlate well with RIA measurements. This assay offers rapid sample turn-around times, making same-day results for outpatient drug monitoring possible.

Cyclosporins↗
PubMed1988

Current experience with renal transplantation in older patients.

Older patients (greater than 50 years old) are generally considered to be at high risk in renal transplantation, particularly those receiving cadaveric kidneys. The outcome in 53 older patients (mean age, 54 years; range, 50 to 64 years) receiving transplants between January 1, 1980 and December 31, 1986 and followed through June 30, 1987 were analyzed. Before 1984, immunosuppression consisted of azathioprine and prednisone (AP); thereafter, triple therapy (TT)--low-dose cyclosporine, azathioprine, and prednisone--was used. The overall 1-, 3-, and 5-year actuarial patient survival was 87%, 84%, and 84%, respectively. Survival for living related donor (LRD) transplant recipients was 100%, 92%, and 92%; survival for cadaveric (CAD) transplant recipients was 81%, 81%, and 81%. The overall graft survival was 74%, 66%, and 66% at 1, 3, and 5 years, respectively; graft survival was 88%, 81%, and 81% for LRD transplant recipients and 68%, 58%, and 58%, for CAD recipients. The patient and graft survival rates were better in the TT group than in the AP group. Eight patients died after transplantation; six within the first year. The causes of patient death were infection (50%), cardiac (25%), and malignancy (25%). Rejection (56%) and patient death (38%) accounted for most of the grafts lost. Patient and graft survival rates in diabetic patients were not significantly different from survival rates in nondiabetic patients. Results in recipients of ten secondary and one tertiary transplant were poor, with only four of 11 grafts functioning at 1 year.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Incidence and morbidity of cytomegalovirus disease associated with a seronegative recipient receiving seropositive donor-specific transfusion and living-related donor transplantation. A multicenter evaluation.

This retrospective study was conducted to identify the frequency of cytomegalovirus (CMV) disease in seronegative recipients of donor-specific transfusion (DST) and living-related donor (LRD) kidneys from seropositive donors. A total of 151 LRD transplants (TX) were performed at six transplant centers over a 3-year period. A total of 33 patients were identified as having been seronegative (pre-TX) for CMV, yet they had DST and a TX from a seropositive LRD. Of these patients, 12 (36.4%) seroconverted within the first 6 months post-TX and developed clinical CMV disease. Additional patients seroconverted, but did not have evidence of clinical disease and were not tested further. All TX centers, with the exception of one, had seronegative patients that became ill after receiving a seropositive DST/LRD TX. Six patients manifested their disease as a febrile illness with leukopenia and liver enzyme elevations, four had pneumonitis, and two developed CMV ulcerations of the colon (one of whom died from resultant sepsis). Of the 36 seronegative patients who received seronegative DST/LRD TX none became ill with CMV disease. Of the 72 seropositive patients who received DST/LRD TX, only 2 (2.8%) developed CMV illness (one, seropositive into seropositive, the other, seronegative into seropositive). Of the 33 seronegative patients receiving seropositive DST/LRD TX, 17 received antilymphocyte preparations (ALP), and 8 of these became ill (47.1%). Of 16 patients not receiving ALP, 5 (31.3%) developed clinical CMV illness. Of the 33 patients who were identified as having been seronegative for CMV yet received seropositive DST/LRD TX, the 12 who did develop CMV illness had two graft losses, one death, and a serum creatinine for the remaining 9 patients of 2.3 +/- 1.6 at last follow-up. The remaining 21 patients who developed no illness had a serum creatinine of 1.3 +/- 0.6 with no graft losses at the last follow-up. This evidence suggests that a prospective TX recipient who is seronegative for CMV who receives DST/LRD TX from a seropositive family member has a significant risk for developing morbidity related to clinical CMV illness.

Adolescent↗
PubMed1988

Alport's syndrome: risk of glomerulonephritis induced by anti-glomerular-basement-membrane antibody after renal transplantation.

Two patients with Alport's syndrome developed glomerulonephritis induced by anti-glomerular-basement-membrane (anti-GBM) antibody after renal transplantation. One patient presented at 5 months after transplantation the second patient 18 months after transplantation. Both grafts failed and the patients returned to dialysis. Our observations suggest that the patients with Alport's syndrome are at risk of developing anti-GBM antibody type glomerulonephritis in the transplanted kidney. This does not occur in the early period after transplantation, probably because of heavy immunosuppression.

Adult↗
PubMed1988

Clinical variability of cyclosporine pharmacokinetics in adult and pediatric patients after renal, cardiac, hepatic, and bone-marrow transplants.

The most important limitation associated with the clinical use of cyclosporine is the narrow therapeutic range between its efficacy and toxicity. Effective treatment is further complicated by significant variation in intrapatient and interpatient pharmacokinetics of the drug. We describe a practical approach to pharmacokinetic analysis that does not interfere with the cyclosporine dosage regimen or with clinical management of the patient. To optimize therapy, we individualized patient management by using noncompartmental pharmacokinetic analysis. Mean residence time (MRT) and volume of distribution at steady-state were calculated from data on concentration vs time after dose. We applied this approach to 24 kidney, 12 heart, 8 bone-marrow, 7 liver, and 5 pancreas transplants. Individualized requirements for cyclosporine dose and dosage interval can be predicted from these parameters. MRT is the most useful pharmacokinetic parameter, because it allows prediction of the optimal dosage interval.

Adult↗
PubMed1988

Comparison of Abbott TDx fluorescence polarization immunoassay, Sandoz radioimmunoassay, and high-performance liquid chromatography methods for the assay of serum cyclosporine.

We have had the opportunity to compare the new FPIA method for the measurement of serum Cs to established assays. The technique used a precipitation step prior to the fluorescence polarization measurement. We compared serum HPLC and RIA to the FPIA procedure. The within run coefficients of variation were 7.2%, 9.5%, and 4%, respectively. Between run CVs were 8.0%, 12.2%, and 3.8%. The correlation coefficient for HPLC and both of the immunoassays was less than 70%, showing the influence of the different specificities of the techniques. Medical centers that have based patient care on the HPLC assay that measures only parent drug will have difficulty using an immunoassay that measures a combination of parent and metabolites. There was a good correlation (R2 = 0.93) between the two immunoassays indicating that those currently using the serum RIA for monitoring could, through careful correlation studies in their patient population, use the FPIA technique. The regression equation was as follows: serum FPIA = 1.27 serum RIA + 1.9. This indicates the higher bias of the FPIA measurements. The advantages of the FPIA assay are that 20 assays could be done in less than one hour. This is in contrast to the longer turnaround time of the standard Sandoz RIA procedure. The technical competence required to perform the assay is less than that needed to perform the current RIA procedure. The assay can be recommended for replacement of the serum RIA; however, a correlation of levels with clinical experience is necessary in view of the difference in values between RIA and FPIA.

Chromatography, High Pressure Liquid↗
PubMed1988

Cyclosporine pharmacokinetics in pancreas transplant recipients.

Ten CsA pharmacokinetic studies were performed on five pancreas transplant recipients to determine proper doses and dosing intervals. These cadaver pancreas transplants were performed with exocrine ductal drainage into the urinary tract through a bladder anastomosis in four cases and into the bowel in one case. Four CsA pharmacokinetic studies were performed on diabetic renal transplant recipients and an additional six studies were performed while with pancreas transplant patients taking metoclopramide in an effort to enhance absorption of CsA. Mean CsA dose was 3.7 mg/kg/dose (range 2.1 to 7.5 mg/kg/dose). All patients but one were on twice daily dosing intervals yielding an average daily dose of 7.4 mg/kg/d. Noncompartmental pharmacokinetic analyses were used. The adequacy of a 1-, 2-, or 3-exponential model was determined by breakpoint analysis of the log concentration v time curve using the F statistic. The terminal rate constant was calculated by nonlinear regression analysis. The AUC and AUMC were calculated by the trapezoidal method with exponential extrapolation and these were used to calculate the MRT and Vdss. The unknown fractional absorption, F, was used to correct the oral data. The average CsA concentration maximum (Cmax) was 528 ng/mL with an average time to maximum concentration (Tmax) of 4.7 hours, a mean residence time of 7.75 hours, with a Vdss/%F of 9.61 L/kg in the pancreas transplant recipients. Additional studies of six patients receiving metoclopramide with CsA revealed an average Cmax of 723 ng/mL, an average Tmax of 2.3 hours, an average MRT of 6.08 hours, and an average Vdss/%F of 5.7% L/kg. These results indicate that coexistent gastroparesis in diabetic recipients of either pancreatic or renal transplants may result in reduced bioavailability of CsA.

Adult↗
PubMed1987

Effect of trimethoprim on serum creatinine in healthy and chronic renal failure volunteers.

The effect of trimethoprim (TMP) on serum creatinine concentration (SCr) was studied in 10 healthy (H) subjects and nine subjects with chronic renal failure (CRF). Each volunteer was given TMP 100 mg perorally every 12 h for 10 days followed by a 7-day washout period. SCr was measured colorimetrically immediately before the study (baseline), on day 10 of TMP, and 7 days after TMP had been discontinued. SCr increased an average of 14.8% from baseline during TMP administration in the H volunteers, but this increase was not statistically significant. During TMP administration to the CRF volunteers, a pronounced elevation (34.6%) of mean SCr from baseline was observed (p less than 0.05). SCr returned to baseline values in both groups following the 7-day washout period. These results are consistent with the hypothesis that TMP competitively inhibits the renal tubular secretion of creatinine.

Adult↗
PubMed1987

Pancreatic allograft exocrine urinary tract diversion. Pathophysiology.

Exocrine secretions of 16 of 22 pancreas allografts were drained into the urinary tract. Seven of these 16 patients have functioning allografts, six with pancreaticocystostomies and one with duct-to-ureter anastomosis. A notable problem has been a chronic metabolic acidosis, along with weight loss and hypotension, secondary to chronic bicarbonate loss and volume depletion through the urinary pancreatic fistula. This occurred as early as one week posttransplant, and intermittently thereafter up to four years. The syndrome was aggravated by episodes of renal dysfunction (acute tubular necrosis or rejection), and febrile syndromes. An inverse relationship between serum and urine bicarbonate concentrations existed, with a correlation coefficient, r = -0.746, (P less than 0.05). A negative correlation was also noted between serum bicarbonate and serum creatinine, r = 0.726, (P less than 0.05). Hyperchloremic metabolic acidosis with normal anion gap occurred despite periods of marginal pancreas allograft function resulting from ongoing rejection. Treatment consisted of intravenous and/or oral bicarbonate supplementation, and bicarbonate dialysis for uremic patients. In addition, one patient was first seen with severe balanitis and urethritis due to documented activation of trypsinogen and chymotrypsinogen, presumably caused by recurrent episodes of urinary tract infection. Urinary assay revealed a 10(2-3) increase in activated trypsin and chymotrypsin in comparison with other asymptomatic allograft recipients. Conversion to ductal enteric drainage led to resolution of both the balanitis and bicarbonate wasting. Measurement of urinary amylase levels were gross indicators of graft viability since no correlation could be found between these levels, onset of hyperglycemia, and eventual graft rejection confirmed by pathological examination.

Acidosis↗
PubMed1987

The effect of oral metoclopramide on the absorption of cyclosporine.

This study was performed to determine the effect of coadministered oral metoclopramide on the absorption of oral cyclosporine in 14 kidney transplant patients. The study was conducted on two consecutive days. Ten patients were studied twice, and 4 patients once, giving 24 studies. The total dosage of metoclopramide was 20 mg. The day on which metoclopramide was administered was chosen randomly. Whole-blood cyclosporine levels were analyzed by high-performance liquid chromatography. Coadministration of cyclosporine with metoclopramide resulted in a significant increase in mean maximum blood concentration (567 ng/ml versus 388 ng/ml) and mean area under the blood-concentration-versus-time curve (4120 ng X hr/ml versus 3370 ng X hr/ml); and a significant decrease in mean time to reach maximum concentration. The mean increase in area under the blood-concentration-versus-time curve was 29%. No significant changes were observed in the elimination of cyclosporine when it was coadministered with metoclopramide. These observations suggest that coadministered metoclopramide increased the total absorption of cyclosporine. Metoclopramide has been shown to hasten gastric emptying; since cyclosporine is absorbed predominantly in the small intestine, coadministration of metoclopramide resulted in increased bioavailability of cyclosporine.

Adult↗
PubMed1987

Autodigestion of the glans penis and urethra by activated transplant pancreatic exocrine enzymes.

A case of synchronous kidney and pancreas transplantation in which a whole pancreas graft had been drained to the urinary bladder is discussed. On the 137th postoperative day, the patient presented with symptomatic balanitis and urethritis. Documented enzymatic activation of the trypsinogen/chymotrypsinogen, which is not present in symptom-free control patients, was thus thought to be responsible for these symptoms. Conversion to enteric drainage by means of a Roux-en-Y loop resulted in resolution of both symptoms and urinary enzymatic activation. Recurrent urinary tract infections were thought to be the most likely mechanism responsible for these findings.

Adult↗