The structure of glycogen phosphorylase b with an alkyldihydropyridine-dicarboxylic acid compound, a novel and potent inhibitor

BACKGROUND: In muscle and liver, glycogen concentrations are regulated by the reciprocal activities of glycogen phosphorylase (GP) and glycogen synthase. An alkyl-dihydropyridine-dicarboxylic acid has been found to be a potent inhibitor of GP, and as such has potential to contribute to the regulation of glycogen metabolism in the non-insulin-dependent diabetes diseased state. The inhibitor has no structural similarity to the natural regulators of GP. We have carried out structural studies in order to elucidate the mechanism of inhibition. RESULTS: Kinetic studies with rabbit muscle glycogen phosphorylase b (GPb) show that the compound (-)(S)-3-isopropyl 4-(2-chlorophenyl)-1,4-dihydro-1-ethyl-2-methyl-pyridine-3,5, 6-tricarboxylate (Bay W1807) has a Ki = 1.6 nM and is a competitive inhibitor with respect to AMP. The structure of the cocrystallised GPb-W1807 complex has been determined at 100K to 2.3 A resolution and refined to an R factor of 0.198 (Rfree = 0.287). W1807 binds at the GPb allosteric effector site, the site which binds AMP, glucose-6-phosphate and a number of other phosphorylated ligands, and induces conformational changes that are characteristic of those observed with the naturally occurring allosteric inhibitor, glucose-6-phosphate. The dihydropyridine-5,6-dicarboxylate groups mimic the phosphate group of ligands that bind to the allosteric site and contact three arginine residues. CONCLUSIONS: The high affinity of W1807 for GP appears to arise from the numerous nonpolar interactions made between the ligand and the protein. Its potency as an inhibitor results from the induced conformational changes that lock the enzyme in a conformation known as the T' state. Allosteric enzymes, such as GP, offer a new strategy for structure-based drug design in which the allosteric site can be exploited. The results reported here may have important implications in the design of new therapeutic compounds.     

The mini-micro-epididymal sperm aspiration for sperm retrieval: a study of urological outcomes

Susceptible adults (n = 105) were enrolled into a randomized double-blind study of rimantadine treatment of experimental influenza A infection. Subjects were cloistered for 8 days and challenged with a rimantadine-sensitive strain of influenza A H1N1 virus at the end of the first day. Forty-eight hours after challenge and for 8 days, 54 subjects received placebo and 51 received rimantadine (100 mg orally, twice a day). Symptoms, signs, and pathophysiologies were monitored. Nine subjects were not infected. Seventeen subjects (38%) in the rimantadine and 26 (53%) in the placebo group became ill. A beneficial effect of rimantadine was documented for virus shedding, symptom load, and sinus pain. Rimantadine had no effect on nasal patency, mucociliary clearance, nasal signs, or on symptoms and signs of otologic complications. These results do not support a preventive effect of rimantadine on the development of otologic manifestations of influenza A infection in adults.     

Successful outcome in Swan-Ganz catheter-induced rupture of pulmonary artery

Swan-Ganz catheter-induced pulmonary artery (PA) rupture is rare, with an incidence of 0.016 to 0.2 per cent, but it remains the most dreaded complication in the placement of these catheters with a mortality above 50 per cent. We report two cases of PA rupture after catheter placement. Both patients were managed nonoperatively and without any invasive procedure. They both stopped bleeding after the initial episode and were discharged a few days later. We believe that in the absence of high-risk factors, such as pulmonary hypertension and systemic anticoagulation, PA rupture from a Swan-Ganz catheter can be successfully treated by withdrawal of the catheter and supportive care.     

The risk of acquiring Lyme disease or babesiosis from a blood transfusion

To determine the risk of acquiring Lyme disease or babesiosis from blood transfusion, serum was collected before and 6 weeks after patients received multiple transfusions during cardiothoracic surgery and antibodies to Borrelia burgdorferi and Babesia microti were measured. Of 155 subjects, 149 received 601 total units of packed red blood cells (PRBC) and 48 received 371 total units of platelets. No patient developed clinical or serologic evidence of Lyme disease; 1 (who received 5 units of PRBC) developed clinical and serologic evidence of babesiosis. The risk of acquiring Lyme disease from a transfused unit of PRBC was 0 (95% confidence interval [CI], 0-0.5%) and from a transfused unit of platelets was 0 (95% CI, 0-0.8%); the same risks for babesiosis were 0.17% (95% CI, 0.004%-0.9%) and 0 (95% CI, 0-0.8%), respectively. The risk of acquiring either Lyme disease or babesiosis from a blood transfusion in Connecticut is very low.     

High dose fluticasone propionate, 1 mg daily, versus fluticasone propionate, 2 mg daily, or budesonide, 1.6 mg daily, in patients with chronic severe asthma. International Study Group

Airway inflammation is now regarded as fundamental in the pathogenesis of asthma and treatment with inhaled corticosteroids has proved effective. There is a need for drugs in this category with higher topical potency but fewer side-effects than those presently available. A double-blind, parallel group study was conducted in 671 patients with severe asthma (already taking between 0.8-2.0 mg of inhaled corticosteroid daily) to compare the safety and efficacy of 6 weeks of treatment with inhaled fluticasone propionate (FP), 1 mg daily, to fluticasone propionate, 2 mg daily, and budesonide (BUD), 1.6 mg daily, delivered via a metered-dose inhaler. Peak expiratory flow (PEF), asthma symptoms, and usage of rescue medication were recorded daily by the patient. At each clinic visit (-2, 0, 3 and 6 weeks) morning serum cortisol levels, bone markers and spirometry were assessed. The changes in mean morning PEF from baseline (weeks 1-6) were: FP 2 mg daily +24 l.min-1; FP 1 mg daily +21 l.min-1; BUD 1.6 mg daily +13 l.min-1. A similar rank order for the three treatments was seen for evening PEF, clinic spirometry, reduction of diurnal PEF variation, symptom scores, and requirement for rescue bronchodilators. The mean serum cortisol levels remained well within the normal range in all three groups. Analysis of the geometric mean cortisol ratio (treatment/baseline ratio after 6 weeks treatment) showed a changed rank order, the values being: FP 1 mg daily 1.04; BUD 1.6 mg daily 0.97; FP 2 mg daily 0.88.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of 6alpha-methylprednisolone acetate on an equine osteochondral fragment exercise model

OBJECTIVE: To determine effects of intra-articularly administered 6alpha-methylprednisolone acetate (MPA) in exercised horses with carpal osteochondral fragmentation. ANIMALS: 18 horses: 3 groups of 6 each. PROCEDURE: An osteochondral (chip) fragment was created in 1 randomly chosen middle carpal joint of each horse. Polyionic fluid (PF) was injected into both middle carpal joints of horses in the control group. In horses of the MPA-control group, MPA was injected into the middle carpal joint without an osteochondral fragment; a similar volume of PF was injected into the contralateral middle carpal joint. In the MPA-treated group of horses, 100 mg of MPA was injected into the middle carpal joint containing the osteochondral fragment; a similar volume of PF was injected into the contralateral joint. Injections were administered on postsurgical days 14 and 28, and horses were exercised on a high-speed treadmill for 8 weeks, starting on postsurgical day 15. RESULTS: Clinical improvement in degree of lameness was not associated with MPA administration. Joints that contained an osteochondral fragment and were treated with MPA had lower prostaglandin E2 concentration in synovial fluid, and lower scores for intimal hyperplasia and vascularity in synovial membrane, compared with PF-treated joints. However, articular cartilage erosion and morphologic lesions suggested possible deleterious effect of intra-articular MPA administration. CONCLUSIONS: Some beneficial effects of MPA administration on synovial fluid and synovial membrane were identified; however, the deleterious findings contrast with those associated with triamcinolone acetonide used in a similar model, but agree with other results of MPA administration in normal and abnormal joints.     

Effect of maternal betamethasone administration at midgestation on baboon fetal adrenal gland development and adrenocorticotropin receptor messenger ribonucleic acid expression

Although fetal pituitary ACTH is important to fetal adrenal growth and steroidogenesis in the second half of primate pregnancy, its role in adrenal development and function has not been established in vivo in the first half of gestation. In the present study, therefore, baboons were treated at midgestation with betamethasone to determine the effect of fetal pituitary ACTH on fetal adrenal growth, development, and ACTH receptor and P-450 enzyme messenger ribonucleic acid (mRNA) levels. The administration of betamethasone to baboon mothers on days 60-99 of gestation (term = 184 days) decreased fetal pituitary POMC mRNA levels by 54% (P < 0.01) and fetal serum ACTH levels to undetectable values (P < 0.05). The decline in ACTH was associated with decreases in fetal adrenal weight (P < 0.001), cortical cell size (P < 0.05), appearance of apoptosis and cellular disorganization, and a loss of immunocytochemically demonstrable definitive zone-specific delta5-3beta-hydroxysteroid dehydrogenase expression. The concomitant administration of ACTH and betamethasone restored these aspects of adrenal integrity to normal. Moreover, there was approximately a 95% decrease (P < 0.01) in fetal adrenal expression of ACTH receptor, P-450 cholesterol side-chain cleavage, and P-450 17alpha-hydroxylase 17/20-lyase mRNA levels after betamethasone administration. We conclude that fetal pituitary ACTH is necessary for the growth and development of fetal and definitive cortical zones and the marked coordinated increase in ACTH receptor and maintenance of P-450 cholesterol side-chain cleavage/P-450 17alpha-hydroxylase 17/20-lyase expression in the baboon fetal adrenal gland during the first half of gestation.     

Age differences in behaviors leading to completed suicide

Nonclostridial necrotizing soft-tissue infections are usually polymicrobial, with greater than 90 per cent involving beta-hemolytic streptococci or coagulase-positive staphylococci. The remaining 10 per cent are usually due to Gram-negative enteric pathogens. We describe the case of a 46-year-old woman with bilateral lower extremity fungal soft tissue infections. She underwent multiple surgical debridements of extensive gangrenous necrosis of the skin and subcutaneous fat associated with severe acute arteritis. Histopathological examination revealed Aspergillus niger as the sole initial pathogen. Despite aggressive surgical debridement, allografts, and intravenous amphotericin B, her condition clinically deteriorated and she ultimately died of overwhelming infection. Treatment for soft-tissue infections include surgical debridement and intravenous antibiotics. More specifically, Aspergillus can be treated with intravenous amphotericin B, 5-fluorocytosine, and rifampin. Despite these treatment modalities, necrotizing fascitis is associated with a 60 per cent mortality rate. Primary fungal pathogens should be included in the differential diagnosis of soft-tissue infections.