Residues at the subunit interfaces of the nicotinic acetylcholine receptor that contribute to alpha-conotoxin M1 binding

The two binding sites in the pentameric nicotinic acetylcholine receptor of subunit composition alpha2 beta gamma delta are formed by nonequivalent alpha-gamma and alpha-delta subunit interfaces, which produce site selectivity in the binding of agonists and antagonists. We show by sedimentation analysis that 125I-alpha-conotoxin M1 binds with high affinity to the alpha-delta subunit dimers, but not to alpha-gamma dimers, nor to alpha, gamma, and delta monomers, a finding consistent with alpha-conotoxin M1 selectivity for the alpha delta interface in the intact receptor measured by competition against alpha-bungarotoxin binding. We also extend previous identification of alpha-conotoxin M1 determinants in the gamma and delta subunits to the alpha subunit interface by mutagenesis of conserved residues in the alpha subunit. Most mutations of the alpha subunit affect affinity similarly at the two sites, but Tyr93Phe, Val188Lys, Tyr190Thr, Tyr198Thr, and Asp152Asn affect affinity in a site-selective manner. Mutant cycle analysis reveals only weak or no interactions between mutant alpha and non-alpha subunits, indicating that side chains of the alpha subunit do not interact with those of the gamma or delta subunits in stabilizing alpha-conotoxin M1. The overall findings suggest different binding configurations of alpha-conotoxin M1 at the alpha-delta and alpha-gamma binding interfaces.     

Changes in the function of lymphocyte blast formation with aging estimated by ethidium bromide fluorescence assay

Modification of DNA with aging has been proposed as a mechanism of cellular senescence. To test this hypothesis, we measured fluorescence of the DNA-Ethidium bromide (EB) complex in human peripheral lymphocytes. Lymphocytes were incubated in a medium containing phytohemagglutinin (PHA-P). EB was linked to lymphoblast-DNA. Healthy adults of three age groups were examined: 40-49 (N = 14), 50-59 (N = 16), 60-69 (N = 8). Moreover, we studied lymphocytes from 17 patients (47-74 years old) with probable Alzheimer's disease. An aged-related linear decrease in fluorescence intensity was found in healthy controls (r = 0.135, p < 0.05), and for Alzheimer's disease patients (r = 0.443, P < 0.10). The regression equation are: Y = -0.0405X + 7.164 (Healthy Controls) Y = -0.121X + 11.258 (Alzheimer's disease patients) where X and Y are age and fluorescence, respectively. These results indicate that the analysis of DNA-EB fluorescence in lymphocytes may be useful in the study of changes associated with aging, and also in the evaluation of the clinical diagnosis of Alzheimer's disease.     

Remnants of chylomicron and very low density lipoprotein impair endothelium-dependent vasorelaxation

Given the multiple impairments in host defense that occur during HIV infection, patients with AIDS are at risk for a variety of pleural infections and neoplasms. Of infectious causes, bacterial parapneumonic effusions and empyemas and tuberculous pleurisy occur more frequently than effusions caused by P. carinii. In each case, therapy is directed at eradication of the causative organisms. In the setting of systemic Kaposi's sarcoma, pleural involvement is common, although diagnosis is difficult and therapeutic options are limited. Pleural effusions caused by non-Hodgkin's lymphoma often occur in the setting of pulmonary parenchymal disease and can be diagnosed cytologically. The recently described entity of primary effusion lymphoma occurs in the absence of solid-organ involvement. The development of a spontaneous pneumothorax in a HIV-infected individual should prompt a search for P. carinii infection. Although these pneumothoraces often recur and are difficult to manage, recent series suggest that surgical approaches to bronchopleural fistulas are reasonable in selected patients.     

Pharmacological effects of SA96 (bucillamine) and its metabolites as immunomodulating drugs--the disulfide structure of SA-96 metabolites plays a critical role in the pharmacological action of the drug

SA96 (generic name, bucillamine) is a disease-modifying anti-rheumatoid arthritis (RA) drug with immunological effects. This compounds has two sulfhydryl groups in its molecule, and the differences and similarities between this drug and D-penicillamine, which is also a sulfhydryl group-containing anti-rheumatic drug, have frequently been discussed. To clarify the pharmacological differences between these two drugs, we examined the concentrations of the compounds and its metabolites in serum and synovial fluid, paying special attention to the metabolites of SA96 produced in vivo. SA96 was metabolized in a very short time to SA981 which is a disulfide compound formed by intramolecular binding of two sulfhydryl groups, and transferred to synovial fluid. In addition SA981 had significant suppressive effects on IL-6 and IL-8 production by synovial cells in vitro. These results demonstrate that SA96, which has two sulfhydryl groups, exhibits anti-rheumatic effects via a pharmacological action clearly different from that of D-penicillamine.     

Protection of mammalian cells from the toxicity of bleomycin by expression of a bleomycin-binding protein gene from Streptomyces verticillus

PURPOSE: To investigate the effects of radiation on anorectal function in patients with carcinoma of the uterine cervix. METHODS AND MATERIALS: Anorectal manometry was carried out on 24 patients (complication group) with late radiation proctitis. All of the manometric data from these patients were compared with those from 24 age-matched female volunteers (control group), in whom radiation treatment had not yet been performed. RESULTS: Regardless of the severity of proctitis symptoms, 25% of patients demonstrated all their manometric data within the normal range, but 75% of patients exhibited one or more abnormal manometric parameters for sensory or motor functions. Six patients (25%) had an isolated sensory dysfunction, eight patients (33.3%) had an isolated motor dysfunction, and four patients (16.7%) had combined disturbances of both sensory and motor functions. The maximum tolerable volume, the minimal threshold volume, and the urgent volume in the complication group were significantly reduced compared with those in the control group. The mean squeeze pressure in the complication group was significantly reduced, whereas the mean resting pressure and anal sphincter length were unchanged. CONCLUSIONS: Physiologic changes of the anorectum in patients with late radiation proctitis seem to be caused by a variety of sensory and/or motor dysfunctions in which many different mechanisms are working together. The reduced rectal reservoir capacity and impaired sensory functions were crucial factors for functional disorder in such patients. In addition, radiation damage to the external anal sphincter muscle was considered to be an important cause of motor dysfunction.     

Analysis of multiple indicator dilution curves for estimation of renal tubular transport parameters

A model is developed to estimate the renal tubular secretory parameters by the multiple indicator dilution (MID) technique. The model allows the calculation of influx (from plasma space to tubular cell), efflux (from tubular cell to plasma space) and sequestration (from tubular cell to luminal side) rate constants. A program using the MID-statistical analysis with least squares fitting (SALS) system for the estimation of these parameters is presented. A trapezoid rule and a non-linear least squares regression were used to carry out definite integrals of cubic spline function and least squares fitting, respectively. The system presented seems to be useful for the precise and rapid estimation of the tubular secretory rate constants.     

Mutation involving cytochrome P450IID6 in two Japanese patients with neuroleptic malignant syndrome

Traumatic injuries of arteries lead to acute bleeding or ischemia. In the hand, which is perfused by two arteries, this symptom could be missed. The hypothenar hammer syndrome is a traumatic occlusion of the distal arteria ulnaris. Dependent on the mechanism of the trauma the clinical symptoms may appear late. A specific angiographic or duplex sonographic diagnostic investigation is necessary to show the arterial occlusion. There is no proven therapeutic procedure. Exact diagnosis of the occlusion as an effect of the trauma is important for the patient and is the basis of any therapeutic intervention.     

Magnetic and insulating properties of electrical steel with a new insulating coating

New inorganic-organic coatings for nonoriented electrical sheets have been developed. Smooth and dull sheets having surface roughnesses of 0.18 μm. H root mean square (rms) and 0.75 μm. H rms, respectively, were coated with different weights of a bichromate-emulsion resin solution. Another sheet having a surface roughness of 0.18 μm. H rms was treated with a bichromate-emulsion resin solution containing a dispersed polyethylene resin powder to provide surface roughness. Results indicated that this third sheet exhibits a higher lamination factor and surface resistivity than the coated sheet whose surface roughness is provided by the dullness of the sheet itself. Moreover, it has a lower core loss and requires less ac exciting current when used in welded motor cores at given thicknesses. When weldability is not a factor, then the smooth sheet having a surface roughness of 0.18 μm. H rms and treated with the inorganic-organic coating is the most suitable: it has the highest lamination factor, the least amount of core loss, and requires the least amount of ac exciting current.