Influence of hydrophobicity on the ion exchange selectivity coefficients for aromatic amines

Hydrophobic effects could play an important role in determining the selectivity of organic ions for ion-exchange resins in aqueous solutions. We used the octanol-water partition coefficient (P) and the chromatographic capacity factor (K') as indices of hydrophobicity of a series of primary and secondary amines, and examined their relationships with the amine selectivity coefficient (K) in binding to the Amberlite IRP-69 ion-exchange resin. Good correlations were found between log K versus log P and log K versus log K', but the relationship appears to be dependent on the degree of substitution at the amino nitrogen. These relationships may be useful for the estimation of selectivity coefficients of various amine drug candidates when they are considered for incorporation with ion-exchange resins in potential controlled-release systems.     

C-terminal modifications of nonpeptide renin inhibitors: improved oral bioavailability via modification of physicochemical properties.

We describe the development of a series of soluble, potent, and bioavailable nonpeptide renin inhibitors. These inhibitors derived from a series of novel nonpeptide renin inhibitors which were recently identified in our laboratories, by alteration of the nature of the C-terminus (P2') of the molecules. Introduction of basic substituents into modified hydroxyethylene dipeptide isosteres gave inhibitors with improved solubility as well as improved potency against human plasma renin. In addition, these modifications produced inhibitors which displayed markedly improved intraduodenal bioavailability in both the ferret and cynomolgus monkey. We also present data which demonstrate excellent efficacy in the monkey for A-74273 (65), with an intraduodenal bioavailability of 16 +/- 4% in the monkey, compared to 1.7 +/- 0.5% for the dipeptide renin inhibitor enalkiren (A-64662, 75). A-74273 is an example of a nonpeptide inhibitor which possesses a good balance of the desirable properties of potency, solubility, and lipophilicity and which is well absorbed into the intestine.     

The effect of bile duct ligation and bile diversion on FK506 pharmacokinetics in dogs.

Mongrel or beagle dogs were submitted to bile duct ligation, or to extraenteric biliary diversion by means of choledochoureterostomy. The kinetics of intravenously administered FK506 was not changed from control status two weeks after bile duct ligation, but the bioavailability of orally administered FK506 was nearly quadrupled. Following oral administration, the absorption of FK506 was highly variable. The results indicate that in dogs FK506 is absorbed from the intestine just as efficiently in the absence of enteric bile and in presence of exogenous bile salt supplement when compared with its absorption in presence of normal bile drainage. These findings with FK506 are different from those with cyclosporine after biliary obstruction or diversion and will have important practical as well as experimental ramifications.     

Preparation and identification of monoclonal antibodies against Penicillium marneffei]

OBJECTIVE: To prepare and identify monoclonal antibodies (mAbs) against Penicillium marneffei. METHODS: Recombinant mannoprotein1 (MP1) of Penicillium marneffei was used to immunize BALB/c mice, and anti-MP1 mAbs were obtained by means of hybridoma. Screening and identification of the mAbs were subsequently performed with indirect enzyme-linked immunosorbent assay and Western blotting, respectively. RESULTS: Four hybridomas producing antibodies against Penicillium marneffei were obtained, and the IgG isotypes of the 4 mAbs were identified as IgG1 with affinity constants (K) of 8.2x10(-9), 4.7x10(-9), 6.5x10(-9) and 2.7x10(-9), respectively. Western blotting demonstrated specific recognition of Aspergillus fumigatus MP1 by the obtained mAbs. CONCLUSION: The 4 hybridomas producing anti-MP1 mAbs with high specificity and affinity can be of significant value in the diagnosis of Penicilliosis marneffei infections.     

Mycophenolate Mofetil Is Associated with Altered Expression of Chronic Renal Transplant Histology

Mycophenolate mofetil (MMF) reduces acute rejection in controlled trials of kidney transplantation and is associated with better registry graft survival. Recent experimental studies have demonstrated additional antifibrotic properties of MMF, however, human histological data are lacking. We evaluated sequential prospective protocol kidney biopsies from two historical cohorts treated with cyclosporine (CSA)-based triple therapy including prednisolone and either MMF (n = 25) or azathioprine (AZA, n = 25). Biopsies (n = 360) were taken from euglycemic kidney-pancreas transplant recipients. Histology was independently assessed by the Banff schema and electron microscopic morphometry. MMF reduced acute rejection and OKT3 use (p < 0.05) compared with AZA. MMF therapy was associated with limited chronic interstitial fibrosis, striped fibrosis and periglomerular fibrosis (p < 0.05-0.001), mesangial matrix accumulation (p < 0.01), chronic glomerulopathy scores (p < 0.05) and glomerulosclerosis (p < 0.05). MMF was associated with delayed expression of CSA nephrotoxicity, reduced arteriolar hyalinosis, striped fibrosis and tubular microcalcification (p < 0.05-0.001). The beneficial effects of MMF remained in recipients without acute rejection. Retrospective analysis shows that MMF therapy was associated with substantially reduced fibrosis in the glomerular, microvascular and interstitial compartments, and a delayed expression of CSA nephrotoxicity. These outcomes may be due to a limitation of immune-mediated injury and suggest a direct effect of reduced fibrogenesis.     

The importance of nucleus accumbens in nicotine-induced locomotor activity

Bilateral injections of either nicotine (200 micrograms) or cytisine (30 or 60 micrograms) into the nucleus accumbens elicited locomotor hyperactivity in rats. Pretreatment with mecamylamine (2 mg kg-1, s.c.) was effective in attenuating the stimulatory effect of either nicotine or cytisine. This study suggests that nicotinic agonists such as nicotine and cytisine produce their locomotor excitatory effects through stimulation of the mesolimbic dopaminergic pathway.     

Single-center experience with primary orthotopic liver transplantation with FK 506 immunosuppression.

OBJECTIVE: The efficacy for primary orthotopic liver transplantation of a new immunosuppressive agent, FK 506 (tacrolimus, Prograf, Fujisawa USA, Deerfield, IL), was determined. SUMMARY BACKGROUND DATA: After 3 years of preclinical research, a clinical trial of FK 506 for orthotopic liver transplantation was begun in February 1989, first as a rescue therapy for patients with intractable rejection with conventional immunosuppression, then as a primary drug. METHODS: Between August 1989 and December 1993, 1391 recipients (1188 adult and 203 pediatric) of primary liver allografts were treated with FK 506 from the outset. Results from these patients were analyzed and compared with those of 1212 historical control patients (971 adult and 241 pediatric) given cyclosporine-based immunosuppression. RESULTS: Actuarial survival at 4 years was 86.2% with FK 506 versus 65.5% with cyclosporine in the pediatric patients (p < 0.0000) and 71.4% versus 65.5% in the adults (p < 0.0005). The need for retransplantation was reduced significantly for FK 506 patients. Four-year graft survival was 77.0% with FK 506 versus 48.4% with cyclosporine in the pediatric patients (p < 0.0000), and 61.9% with FK 506 versus 51.4% with cyclosporine in the adult recipients (p < 0.0000). Regression analysis revealed that reduction in mortality or graft loss from uncontrollable rejection, sepsis, technical failure, and recurrent original liver disease were responsible for the improved results with FK 506 therapy. CONCLUSIONS: FK 506 is a potent and superior immunosuppressive agent for orthotopic liver transplantation.     

The different effects of Helicobacter pylori strains on basal and histamine-stimulated acid and pepsin production: An in vitro study

Inflammation Research -