The two steps of group II intron self-splicing are mechanistically distinguishable

The two transesterification reactions catalyzed by self-splicing group II introns take place in either two active sites or two conformations of a single active site involving rearrangements of the positions of the reacting groups. We have investigated the effects on the rates of the chemical steps of the two reactions due to sulfur substitution of nonbridging oxygens at both the 5' and 3' splice sites as well as the deoxyribose substitution of the ribose 2' hydroxyl group at the 5' splice site. The data suggest that the two active sites differ in their interactions with several of these groups. Specifically, sulfur substitution of the pro-Sp nonbridging oxygen at the 5' splice site reduces the chemical rate of the step one branching reaction by at least 250-fold, whereas substitution of the pro-Sp oxygen at the 3' splice site has only a 4.5-fold effect on the chemical rate of step two. Previous work demonstrated that the Rp phosphorothioate substitutions at both the 5' and 3' splice sites reduced the rate of both steps of splicing to an undetectable level. These results suggest that either two distinct active sites catalyze the two steps or that more significant alterations must be made in a single bifunctional active site to accommodate the two different reactions.     

New use of Foley catheter for precise vesicourethral anastomosis during radical retropubic prostatectomy

PURPOSE: We describe a new method of using a Foley catheter to assist vesicourethral anastomosis during radical retropubic prostatectomy. MATERIALS AND METHODS: A total of 81 patients underwent radical retropubic prostatectomy with this technique. Followup ranged from 4 to 48 months. Peri-catheter urethrograms were performed at 3 weeks. Patients were evaluated specifically for bladder neck contracture, urinary continence and prolonged catheterization. RESULTS: Bladder neck contracture, occurred in 4.9% of the patients and 87.6% were completely continent of urine. Only 1 patient required extended postoperative catheterization. CONCLUSIONS: Use of a Foley catheter for vesicourethral anastomosis is consistent and simple, and provided good surgical results in our experience.     

Stereotactic radiosurgery of malignant and benign intracranial lesions utilizing a patient rotator

The objective of this survey was to demonstrate whether a primary care track internal medicine residency program emphasizing community-based health care of the urban sick poor trains physicians who will continue to practice in general internal medicine or similar fields. Thirty-five primary care residents (100% of graduates) who trained from 1976 through 1993 in the Adult Primary Care Track of the Internal Medicine Residency Program at St. Vincent's Hospital, New York were used as participants.     

Familial jejunal atresia with renal dysplasia

Although jejunal atresia occasionally may occur with a familial pattern, an association with renal disease has not been described. The authors report on three family members treated over two generations, all of whom had both proximal jejunal atresia and renal dysplasia. This association was most likely inherited as an autosomal dominant trait.     

Net glutamate release from astrocytes is not induced by extracellular potassium concentrations attainable in brain

Elevated extracellular potassium concentration ([K+]e) has been shown to induce reversal of glial Na+-dependent glutamate uptake in whole-cell patch clamp preparations. It is uncertain, however, whether elevated [K+]e similarly induces a net glutamate efflux from intact cells with a physiological intracellular milieu. To answer this question, astrocyte cultures prepared from rat and mouse cortices were incubated in medium with elevated [K+]e (by equimolar substitution of K+ for Na+), and glutamate accumulation was measured by HPLC. With [K+]e elevations to 60 mM, medium glutamate concentrations did not increase during incubation periods of 5-120 min. By contrast, 45 min of combined inhibition of glycolytic and oxidative ATP production increased medium glutamate concentrations 50-100-fold. Similar results were obtained in both rat and mouse cultures. Studies were also performed using astrocytes loaded with the nonmetabolized glutamate tracer D-aspartate, and parallel results were obtained; no increase in medium D-aspartate content resulted from [K+]e elevation up to 90 mM, whereas a large increase occurred during inhibition of energy metabolism. These results suggest that a net efflux of glutamate from intact astrocytes is not induced by any [K+]e attainable in brain.     

VRCTC-310--a novel compound of purified animal toxins separates antitumor efficacy from neurotoxicity

Two purified animal venom toxins, crotoxin and cardiotoxin, have been combined to produce a unique natural product (VRCTC-310) currently under investigation as an antitumor agent by the National Cancer Institute. In vitro, it has demonstrated cytotoxic disease specificity and a unique mechanism of action when submitted to COMPARE analysis. In vivo, tolerance was developed to the neurotoxic properties of crotoxin which allowed comparison of several schedules of fixed and escalating daily i.m. doses to mice bearing s.c. Lewis Lung carcinoma. An 83% inhibition of tumor growth was achieved using an escalating dose schedule starting at 1.8 mg/kg and reaching 6.3 mg/kg/day on day 20. Although some irritation around the sites of i.m. injection was noted, animal weight loss was negligible and there were no other signs of adverse toxicity. This natural product represents a new, membrane interactive anticancer agent which produces a unique spectrum of cytotoxicity in vitro and which has demonstrated interesting in vivo antitumor efficacy.     

Centurion syndrome. Idiopathic anterior displacement of the medial canthus

Bone marrow transplantation (BMT) using HLA-partially matched family donors has produced disappointing results (25-30% of long-term survivors) in patients with severe aplastic anemia. We describe two children affected by severe aplastic anemia, not responsive to immunosuppressive therapy, who underwent allogeneic bone marrow transplantation using a HLA-partially matched family donor. Both cases presented 2 first class HLA-antigens (A and B) disparity between donor and recipient. The pretransplant conditioning regimen consisted of cyclophosphamide, thoracoabdominal irradiation, cytosine-arabinoside, and antilymphocyte globulin. As graft versus host disease (GVHD) prophylaxis, Cyclosporine-A was administered at usual dosages for 6 months. A full marrow engraftment was observed in both cases. Only grade I acute GVHD, promptly responsive to corticosteroid therapy, developed with no chronic GVHD. Five months after transplant, both children progressively developed hypertension, renal function impairment, thrombocytopenia, and severe normochromic anemia, with erythropoietin serum levels lower than expected for the haematocrit. After antihypertension treatment and supportive therapy, the clinical picture progressively improved, while treatment with recombinant human erythropoietin completely corrected the long-lasting anemia. The two children are alive and well 28 months after the transplant, with a Karnofsky score of 100% and a normal peripheral blood count. The authors suggest that, once immunosuppressive therapy has failed, BMT from donors other than HLA-identical sibling is a feasible approach in children affected by severe aplastic anemia, not having an HLA-identical donor.