Synthesis and acid ionization constants of cyclic cystine peptides

Cyclic peptide disulfides of the general formula were synthesized from the corresponding peptide derivatives [Boc-Cys(Trt)(Gly)-_n-Cys(Trt)-OBu^t] by oxidation with iodine in methanol and by subsequent removal of the terminal groups with trifluoroacetic acid. Acid ionization constants of the obtained peptides were determined by potentiometric titration in aqueous KCl (0.1 mol/L) medium. All compounds have two dissociable hydrogens, corresponding to carboxyl (pK¹= 2.35–2.84) and to terminal amino group (pK₂= 5.61–6.93); pK₁, values show first an upward and then a downward trend with the increase in ring size; the opposite is true for pK₂, values. These trends could be tentatively attributed to the intramolecular salt bridge (-COO——-NH⁺₃-) formation.     

RAD58 (XRS4)—A new gene in the RAD52 epistasis group

The RAD58 (XRS4) gene of Saccharomyces cerevisiae has been previously identified as a DNA repair gene. In this communication, we show that RAD58 also encodes an essential meiotic function. The spore inviability of rad58 strains is not rescued by a spo13 mutation. The rad50 mutation suppresses spore inviability of a spo13 rad58 strain suggesting that RAD58 acts after RAD50 in meiotic recombination. The rad58-4 mutation does not prevent mitotic recombination events. Haploid rad58 cells fail to carry out G₂-repair of gamma-induced lesions, whereas rad58/rad58 diploids are able to perform some diploid-specific repair of these lesions.     

X-ray converters for medical radioscopy

Spektr Scientific-Industrial Association, Moscow. Research Institute of Radioscopy, S. M. Kirov Tomsk Polytechnic Institute. Translated from Meditsinskaya Tekhnika, No. 1, pp. 3–7, January–February, 1989.     

Alterations of arginase activity in scrapie-infected mice and in amyotrophic lateral sclerosis

We followed the dynamics of arginase activity, the ultrastructural changes, and accumulation of the scrapie agent in the CNS of scrapie-infected mice. The arginase activity has been shown to increase 5-fold within the first 3-4 months of the incubation period followed by subsequent fall at its end. The peak of increased arginase activity coincided with appearance of multilayer membranes, whereas the decrease of this activity was associated with the greatest development of status spongiosus, synaptic degeneration, accumulation of five-layer membranes as well as with maximal accumulation of the scrapie agent in the CNS. Examination of 100 patients with different forms of amyotrophic lateral sclerosis (ALS) revealed a 2-8-fold increase of arginase levels in the cerebrospinal fluid (CSF) as compared with the background levels in the comparative groups of control patients. Similar enzyme alterations in scrapie--and in ALS--are discussed in terms of possible resemblance of their pathogenesis.     

Results of 30 years' surgical treatment of acquired defects and diseases of the heart

A total of 11085 patients have been operated on for rheumatic heart diseases over thirty years, 85.4% of those, for mitral stenosis or its relapse, using the "closed" method (total mortality was 2.7%). In recent years, the mortality rate has dropped to 1.5% in that group of patients. Prevention of heart failure and thromboembolic complications still are the principal problem of mitral commissurotomy. Traumatic regurgitation was seen in 2%. The operation was performed under extracorporeal circulation in 6.2% of patients. Mortality, associated with mitral prosthesis implantation, has decreased threefold (to 10.8%) over 15 years. A total of 131 patients have been operated on for constrictive pericarditis, the mortality rate was 10.7%. Primary implantation of electric pacemaker for complete transverse heart block has been performed in 196 patients, and the generator was replaced in 143 patients.     

Present-day fiber endoscopy in the diagnosis and therapeutic tactics in foreign bodies of the upper digestive tract

Characterization of foreign bodies and their localization in the digestive tract in 404 patients is given. Surgical methods of treatment of such patients are described. Endoscopy was used for examination and treatment. The adequate anesthesia is thought by the authors to be necessary for a successful endoscopic removal of the foreign bodies. The indications for general anesthesia are enumerated. The endoscopic removal of the foreign bodies during surgical interventions are indicated in patients with the perforation of the esophagus by a foreign body.     

The Problem of Device Calibration for the Pharmacopoeial Drug Dissolution Test

Pharmaceutical Chemistry Journal -