Biliverdin reductase from the liver of Atlantic salmon (Salmo salar).

Biliverdin reductase was characterized and purified from the liver of Atlantic salmon (Salmo salar) using a novel enzymatic staining method. The properties of the enzyme are quite different from those of mammals. The purified enzyme is a monomeric protein with a molecular weight of approximately 68 kD and an isoelectric point of around 3.8. The enzyme can utilize both NADH and NADPH as coenzyme, but the kinetic properties of the NADH-dependent and the NADPH-dependent enzyme activities are different: K(m) value for biliverdin IXalpha is 0.6 microM in the NADPH system, while it is 6.8 microM in the NADH system. Both enzyme activities are inhibited by excess biliverdin IXalpha, but the NADPH-dependent enzyme activity is far more susceptible. The optimum pH for activity is 5.5 with NADPH and 6.0 with NADH. The optimum reaction temperature is 35 degrees C.

Purification and characterization of biliverdin IXalpha from Atlantic salmon (Salmo salar) bile.

Biliverdin IXalpha was purified from the bile of Atlantic salmon (Salmo salar) using a silica gel (Wakogel C-200) column. The yield was 49.5 mg per 100 ml of fresh bile and purity 95.3%. The biliverdin IXalpha in the bile was quite stable when the bile was frozen at -80 degrees C for a period of 40 days. However, 7.1% of the biliverdin IXalpha was lost when the bile was stored at 4 degrees C for 20 days. The purified biliverdin IXalpha appeared as a single spot with Rf value of 0.25-0.27 on thin layer chromatography (TLC) and one main peak on high performance liquid chromatography (HPLC) at 436 or 650 nm. When the biliverdin IXalpha was subjected to enzymic reduction with highly purified biliverdin reductase, two clear isobestic points were seen, at 384 and 670 nm. When the products of the reaction with biliverdin IXalpha were extracted in butanol after completion of the reaction, one absorbance peak was observed at 468 nm. The time course of the reduction of biliverdin IXalpha to bilirubin IXalpha catalyzed by biliverdin reductase depended on reduced pyridine nucleotide. The time course of the NADPH-dependent reaction is different from that of the reaction with NADH. In the reduction of biliverdin IXalpha, per mole of biliverdin IXalpha reduced or per mole of bilirubin IXalpha formed 1 mole of reduced pyridine nucleotide was consumed in both the NADH and NADPH systems.

Solid-phase synthesis of muramyl dipeptide (MDP) derivatives using a multipin method.

Solid-phase synthetic method of muramyl dipeptide derivatives is reported. A diverse library of muramyl dipeptides could be potentially synthesized by acylation, reductive alkylation, sulfonamide formation, urea formation, N-alkylation, amine addition, or component Ugi reactions based on this method for drug screening.

Systematic study of the substituted active C-terminus of hirudin.

Hirudin, a potent clinical thrombin inhibitor from Hirudo medicinalis, consists of 65 amino acids in a single chain. In this paper, we systematically synthesize a series of C-terminal (desulfo hirudin45-65) peptides substituted by 20 natural L-amino acids via the Multipin method. The resulting peptide library is subsequently screened using an alpha-thrombin-mediated fibrinogen clotting assay and alpha-thrombin-induced amidolytic hydrolysis assay.

Effect of timing of cyclosporine administration on recovery from renal ischemia in rats.

The effect of timing of cyclosporine administration on functional recovery from renal ischemia was studied in Sprague-Dawley rats. Animals were given cyclosporine and subjected to renal ischemia by temporarily occluding both the renal artery and vein. Our data demonstrate no significant difference in serum creatinine among rats subjected to renal ischemia, cyclosporine, or cyclosporine-vehicle cremophor EL administration, or the control group. On the other hand, renal ischemia in combination with cyclosporine resulted in rapid and marked deterioration in renal function with serum creatinine peaking on Day 2. The most significant rise was in rats that received cyclosporine 4 hr prior to induction of renal ischemia (4.7 +/- 0.5 mg/dl), followed by those that received cyclosporine 4 and 24 hr postischemia (2.8 +/- 0.5 and 3.2 +/- 0.7 mg/dl, respectively). Cyclosporine administration 24 hr prior to renal ischemia resulted in the least elevation of the serum creatinine (2.1 +/- 0.5 mg/dl) and the earliest return to the baseline value. Our data suggest that the timing of cyclosporine administration in rats subjected to renal ischemia influences the extent of renal injury and the subsequent recovery of renal function.

Renal transplantation from elderly living donors.

A worldwide shortage of cadaveric donors has led to the increased utilization of elderly living donors, with controversial results. In an attempt to assess the effect of donor age on graft survival and subsequent renal function, we analyzed our clinical results in 276 consecutive recipients of living related renal transplants spanning both the cyclosporine and the azathioprine eras, of whom a total of 44 recipients received kidneys from donors over 55 years old. All recipients were otherwise similar in age, race, haplotype mismatch, number of retransplants, and number of pretransplant transfusions, apart from an increased number of diabetics among the CsA-treated recipients of elderly kidneys (38% vs. 14%). The cumulative patient and graft survival rates at 1 and 5 years were independent of donor age whether CsA or AZA was utilized. Nor was the incidence of rejection or infection significantly different in the older donor group when compared with the younger cohort. Short-term and intermediate-term renal function, as assessed by serum creatinine, was however poorer but stable in the older donor group when compared with the younger one. The mean serum creatinine levels at 1 year in the CsA- and AZA-treated recipients of kidneys from older donors were 2.4 and 2.0 mg/dl, respectively, compared with 1.6 and 1.4 mg/dl, respectively, when the donor age was less than 55 years (P less than 0.001). Since renal function at the end of the first posttransplant year is considered a determinant of long-term graft survival, this is a cause for concern, but in view of the universal shortage of organs and the negligible morbidity to donors, renal transplantation from elderly living donors remains an acceptable practice.

Diabetes mellitus after renal transplantation in the cyclosporine era--an analysis of risk factors.

Despite mounting experimental evidence that cyclosporine inhibits pancreatic islet cell function, clinical data on posttransplant diabetes mellitus (PTDM) in renal allograft recipients in the cyclosporine era are scarce. Between June 1983 and December 1988, 39 of 337 (11.6%) cyclosporine-treated adult renal transplant recipient whose grafts survived longer than 1 year developed PTDM. Of these, 43.6% and 74.4% were diagnosed by 3 and 12 months posttransplant, respectively, and 51.3% were insulin-dependent. Incidence of PTDM was highest in blacks (19.8%) and Hispanics (21.3%) and in those with HLA-A 30 and Bw 42 antigens. Older recipients and those that received cadaveric kidneys were more likely to develop diabetes than those who received living related allografts (14% vs. 5.3%, P less than 0.05). The rate of PTDM appeared to be independent of the type of induction, immunosuppressant therapy, incidence of rejection, total steroid and cyclosporine dose, percentage of body weight gain in the first posttransplant year, and serum creatinine concentration. Actuarial 5-year, decaying from 100% at 1 year, patient and graft survival rates were 87% and 70%, respectively, in the PTDM group compared with 93% and 90%, respectively, in controls. Causes of graft failure among the diabetics included chronic rejection (6), patient death (3), noncompliance with immunosuppressants (2), and sepsis (1). The incidence of infectious complications was significantly higher in the PTDM group compared with the control group (53% vs. 16%, P less than 0.05), with all 5 deaths among the diabetics being sepsis-related.

Prolonged simple cryothermic immersion storage of rat heart isografts: a preliminary study.

In order to extend preservation time for heart transplant, cryothermic immersion storage was studied in a rat heart isograft model. Rat hearts preserved at -2 to 0 degrees C for up to 96 h were successfully transplanted with no deleterious effects noted on defrosting and reperfusion with long-term survival beyond 60 days of transplant.

HLA-identical renal transplants: impact of cyclosporine on intermediate-term survival and renal function.

Seventy-two and 34 consecutive HLA-identical sibling renal transplant recipients were treated with azathioprine/prednisone (AZA; follow-up, 5.0 years) and cyclosporine/prednisone (CSA; mean follow-up, 2.9 years), respectively. Both groups were similar in age, sex, race, and number of transplants, but there were more diabetics in the CSA group (34% v 8%). Actual patient survival at 1 year and actuarial patient survival at 5 years were 100% and 96%, respectively in the CSA group compared with an actual patient survival of 91% and 82% at 1 and 5 years, respectively, in the AZA group. Actual graft survival at 1 year improved from 85% in the AZA group to 97% in the CSA-treated recipients (P less than 0.05). Mean serum creatinine at 5 years remained stable in the AZA group at a mean of 123 mumol/L (1.4 mg/dL) compared with a progressive increase in this parameter to a mean of 212 mumol/L (2.4 mg/dL) after the same time interval in the CSA patients. Furthermore, the slopes of the serum creatinine against time were significantly different between the two groups (P less than 0.01). Mean daily CSA dose averaged 4 mg/kg 12 months following transplantation, with a decrease to 2.4 mg/kg by the fifth year. Causes of death in the AZA group were cardiovascular (eight), sepsis (three), cancer (one); and in the CSA group, Kaposi's sarcoma (one). Causes of graft failure in the AZA group were immunological (six), sepsis (three), technical (two), recurrence of disease (one), and patient death with a functioning graft (five). Technical (one), noncompliance (two), recurrence of disease (one), and patient death with a functioning kidney (one) caused graft failure in the CSA group. No difference in posttransplantation serum cholesterol or incidence of new onset diabetes was observed between the two groups, but hypertension was significantly more frequent (51% v 21%, P less than 0.01) when CSA was used. In conclusion, intermediate-term results of CSA-treated HLA-identical transplant recipients showed improved patient and graft survival with less complications apart from hypertension. However, the slow, but relentless, increase in serum creatinine in the CSA-treated patients compared with those treated with AZA is of concern.