Changes in the electron density of the cofactor NADPH on binding to E. coli dihydrofolate reductase.

Quantum-mechanical electron density calculations reveal that a significant polarization is induced in the cofactor NADPH (reduced nicotinamide adenine dinucleotide phosphate) on binding to the enzyme dihydrofolate reductase. The calculations indicate that electron density corresponding to approximately 0.7 electron charges is shifted within the molecule, extending over more than 20 A.

FASTRUN: a special purpose, hardwired computer for molecular simulation.

We describe the design, construction, and performance of a special purpose, hardwired accelerator for molecular mechanical calculations called FASTRUN. The processor was designed at Columbia University in 1984, constructed in the Instrumentation Division of Brookhaven National Laboratory, and delivered to Columbia in final form in 1989. It was rendered functional for molecular mechanics in early 1990.

Characterization of the role of melanoma growth stimulatory activity (MGSA) in the growth of normal melanocytes, nevocytes, and malignant melanocytes.

Melanoma growth stimulatory activity (MGSA) was originally described as an endogenous growth factor for human melanoma cells. To test the hypothesis that an MGSA autocrine loop is responsible for the partial freedom from growth control observed in nevocytes and melanoma cells, MGSA growth response and MGSA mRNA/protein levels were examined in these cells compared with normal melanocytes. As a single agent, or in combination with other factors, MGSA stimulated the growth of normal human epidermal melanocytes as well as other growth promoters for melanocytes.

The 1989 report of the North American Pediatric Renal Transplant Cooperative Study.

This report of the North American Pediatric Transplant Cooperative Study summarizes data contributed by 57 participating centers on 754 children with 761 transplants from 1 January 1989 to 16 February 1989. Data collection was initiated in October 1987 and follow-up of all patients is ongoing. Transplant frequency increased with age; 24% of the patients were less than 5 years, with 7% being under 2 years.

Pharmacokinetics of calcitriol in continuous ambulatory and cycling peritoneal dialysis patients.

Oral calcitriol is commonly used for the treatment of secondary hyperparathyroidism in patients undergoing long-term dialysis, but it has been suggested that intravenous (IV) or intraperitoneal (IP) administration enhances the therapeutic efficacy of the sterol. To examine potential mechanisms for this difference, the bioavailability of calcitriol was evaluated after single oral (PO), IV, and IP doses of 60 ng/kg in each of six adolescent patients with osteitis fibrosa undergoing continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD). Serum calcitriol levels were 3.

Effects of recombinant human erythropoietin on HLA sensitization and cell mediated immunity.

Highly presensitized patients wait longer for a renal allograft than unsensitized patients and have a poorer allograft survival rate. Repeated blood transfusions have been implicated in the induction and maintenance of sensitization. To determine the effect of recombinant human erythropoietin (rHuEPO) therapy on five transfusion dependent, highly sensitized adolescents on dialysis, we serially measured percentage panel reactive antibody (%PRA) levels, titers of identifiable discrete anti-HLA Class I antibody specificities, and non-specific indices of cellular immunity before and following initiation of rHuEPO therapy.

Technical factors contributing to successful kidney transplantation in small children.

Cadaveric renal transplantation in small children has not been as successful as either cadaver transplantation in older children, or adults, or living-related transplantation in small children. We report the results of cadaver renal transplantation in 17 children 6 years or younger with only 1 graft lost within 1 year after transplantation. The important technical factors that have enabled these improved results include careful intraoperative fluid management, use of adult kidneys with arterial anastomoses to the common iliac artery or aorta, and sequential immune suppression.

Phase I and pharmacokinetic study of arabinofuranosyl-5-azacytosine (fazarabine, NSC 281272).

A Phase I clinical trial of 1-beta-D-arabinofuranosyl-5-azacytosine (ara-AC or fazarabine) given as a 72-h continuous infusion on a 21-day cycle was conducted in 27 adult patients with refractory cancer. The major toxicity was reversible granulocytopenia and thrombocytopenia. Dose-limiting toxicity was observed at a dose rate of 1.

Descriptions of the participating centers and patient population in the Growth Failure in Children with Renal Diseases Study.

The Growth Failure in Children With Renal Diseases Study, a double-blind, multicenter clinical trial with 108 children entered into the control period over 4.3 years of patient enrollment (December 1984 to April 1989), is being extended for 3 years (December 1988 to December 1991) to provide the time needed to accrue additional patients, aged between 1 1/2 and 10 years, with glomerular filtration rates of 20 to 75 ml/min/1.73 m2.

Cyclobut-A and cyclobut-G, carbocyclic oxetanocin analogs that inhibit the replication of human immunodeficiency virus in T cells and monocytes and macrophages in vitro.

Two newly synthesized carbocyclic oxetanocin analogs, (+/-)-9-[(1 beta,2 alpha,3 beta)-2,3-bis(hydroxymethyl)-1-cyclobutyl]adenine (cyclobut-A) and (+/-)-9-[(1 beta,2 alpha,3 beta)-2,3-bis(hydroxymethyl)-1-cyclobutyl]guanine (cyclobut-G) were tested for activity against the infectivity of human immunodeficiency virus (HIV) in vitro. A number of other carbocyclic oxetanocin analogs failed to exert good antiretroviral effects. Both cyclobut-A and cyclobut-G protected CD4+ ATH8 cells against the infectivity and cytopathic effect of HIV type 1 (HIV-1) and suppressed proviral DNA synthesis in ATH8 cells exposed to HIV-1 in vitro at concentrations of 50 to 100 microM.

Recombinant human growth hormone treatment of children with chronic renal failure: update 1990.

Nine children with growth retardation due to chronic renal failure were treated with recombinant human growth hormone (rhGH) for 12-36 months. Results demonstrated a significant increase in height velocity at each 12-month interval compared with that achieved during the year prior to treatment. However, the increase in bone age was no greater than the increase in chronological age during the period of treatment.

Recombinant human growth hormone (rhGH) treatment of children undergoing peritoneal dialysis.

The authors studied the effect of recombinant growth hormone (rhGH) treatment on 5 growth retarded children, age 2 2/12 to 17 8/12 years, who had end-stage renal disease (ESRD) and were undergoing continuous cycling peritoneal dialysis (CCPD). Patients received 0.125 mg/kg of subcutaneous rhGH 3 times weekly.

Significance of the monocyte crossmatch in living-related transplantation.

It is claimed that antibodies to the vascular-endothelial (VEM) antigen system are responsible for early renal transplant rejection. To evaluate the significance of these anti-VEM antibodies, we performed a retrospective study in 16 patients aged 14.8 +/- 5 (SD) years, who received either a living-related HLA-identical (n = 5) or haplo-identical (n = 11) transplant between 4/79 and 3/84.

In vitro inhibition of the infectivity and replication of human immunodeficiency virus type 1 by combination of antiretroviral 2',3'-dideoxynucleosides and virus-binding inhibitors.

We tested the in vitro inhibitory activities of three 2',3'-dideoxynucleosides and two inhibitors of viral binding in combinations against the infectivity and cytopathic effect of human immunodeficiency virus type 1. 3'-Azido-2',3'-dideoxythymidine, 2',3'-dideoxyinosine, or 2',3'-dideoxycytidine, combined with recombinant soluble CD4 (sCD4), brought about synergistic antiretroviral activity without toxicity at clinically achievable concentrations. Combinations of 2',3'-dideoxynucleosides plus dextran sulfate exerted similar synergistic antiviral effects without concomitant increases in toxicities.

Low molecular weight GTP-binding proteins are associated with neuronal organelles involved in rapid axonal transport and exocytosis.

Recent evidence suggests that low molecular weight GTP-binding proteins may play important roles in a variety of membrane transport processes. In order to address the question of whether these proteins are involved in transport processes in the nerve axon, we have assessed their presence in rapid transport membranes from rabbit optic nerve. We report the characterization of a group of low molecular weight GTP-binding proteins which are constituents of rapid transport vesicles.

Evaluation of cyclosporine nephrotoxicity by renal transplant fine needle aspiration.

Fine needle aspiration is a relatively safe, minimally invasive technique for morphologic evaluation of intragraft events in renal transplant recipients. We assessed the usefulness of this technique in the diagnosis of acute cyclosporine nephrotoxicity (NT). Two aspirate features considered indicative of NT were examined; tubular cell cytoplasmic isometric vacuolization (IV) and isolated graft lymphocytosis.

Accelerated growth after recombinant human growth hormone treatment of children with chronic renal failure.

We studied the effect of recombinant human growth hormone treatment on five boys, aged 4.6 +/- 1.8 years, who had chronic renal failure secondary to congenital renal diseases (mean creatinine clearance (+/- SD): 18.