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Biomedical subjects

A Novak

Publications and source records attributed to A Novak.

At least 55 records · Page 3Linked to original sources
PubMed1987

Acute cervico-facial actinomycosis.

Cervico-facial actinomycosis still occurs occasionally and should be included in the differential diagnosis of infectious processes in the jaws and the oral cavity. The typical actinomycosis-cases are clinically chronic in nature; however actinomycosis may be atypical with subacute or acute clinical manifestations. Among 37 cases of infectious processes in the jaws treated with extraoral incision between 1980 and 1985 in the Department of Oral Surgery, School of Dental Medicine, University of Berne, 3 (8%) were diagnosed as acute actinomycosis according to the following procedure. Prior to incision, pus was aspired under aseptic conditions. Presence of gram-positive branched filaments in the microscopically examined pus led to the suspicion of actinomycosis. This diagnosis was confirmed by cultivation of Actinomyces israelii using the anaerobic culture method, biochemical characteristics and gas-liquid chromatographic analysis of metabolic products. These 3 actinomycosis-cases were successfully treated by surgical removal of the suspicious foci and by administration of clindamycin per os for 16 days.

Actinomyces↗
PubMed1985

The lysosomal hexosaminidase isozymes.

In the 15 years since the demonstration that HEX A is the defective enzyme in patients with TSD, intensive efforts in many laboratories have revealed much about the HEX group of enzymes. In contradistinction to the two isozymes described by Robinson and Stirling [1968], we now know that there are several different species. They include the products of at least three genes which code for the alpha and beta polypeptides as well as for an enzyme that we have called HEX D. The different species of HEX found in human tissues and fluids include significant amounts of larger, unprocessed polypeptides as well as mature enzyme. Thus the HEX A of serum (HEX AS) is a more primitive form of the enzyme than that found in lysosomes. The role of biosynthesis in the formation of multiple species of HEX is not confined to the polypeptide chains of the enzyme. All lysosomal enzymes are glycosylated and HEX is not an exception. The carbohydrate side-chains are essential to the packaging process that places HEX in the lysosome. Carbohydrates on lysosomal HEX species clearly differ from those on HEX in serum. Characterization of HEX oligosaccharides is still in the preliminary stages. Many minor species of HEX have been described. The more important ones are the intermediate isozymes (HEX Is). In tissues the HEX Is appear to contain mixtures of processed and unprocessed alpha and beta polypeptides. In serum, on the other hand, they contain unprocessed beta chains and differ in the carbohydrate side-chains. Most species of HEX show microheterogeneity. Native, mature HEX B separates into several bands on isoelectric focusing. The nature of this microheterogeneity has not been defined. Clear differences have been described, however, between the two chains in the beta subunit. The chains are always united in non-random fashion and are probably derived by cleavage of a single gene product. Studies of hydrolytic activity have been interesting. Like other lysosomal enzymes, HEX A requires a specific protein activator for optimum activity. This small polypeptide has been partially characterized but its mode of action is as yet unclear. Defects in activator synthesis lead to a form of GM2 ganglioside storage disease. Clinically many different phenotypes have been identified which appear to result from defects in each of the HEX genes. The differences between the defects have not been characterized in molecular terms.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1981

[Parenteral antibiotic prophylaxis or oral antimicrobial bowel preparation for colorectal surgery (author's transl)].

A prospective randomized trial was designed to establish whether parenteral antibiotic prophylaxis was as effective as oral antimicrobial bowel preparation in preventing sepsis after colorectal surgery. Patients scheduled for elective resection of colorectal cancer received metronidazole and kanamycin either orally in the preoperative phase or parenterally as a short-term perioperative prophylaxis. The former regimen resulted in reduction of the microbial concentrations in the bowel contents in the absence of therapeutic serum concentrations at the time of operation, whereas the latter achieved therapeutic intraoperative serum levels without altering the colonic microflora. 72 patients were studied. There was no significant difference in the occurrence of postoperative sepsis between the two groups (a total of 72 patients). These results differ from those obtained at the Birmingham General Hospital using the same protocol, in which postoperative sepsis was significantly more common in the group of patients having oral bowel preparation. This difference was most probably due to an overgrowth of kanamycin-resistant coliforms during the period of oral antibiotic preparation. The presence of resistant organisms did not, however, result in failure of systemic prophylaxis. The authors conclude that short-term parenteral application is the safer method of antibiotic prophylaxis in colorectal surgery and is to be preferred to oral antimicrobial bowel preparation.

Administration, Oral↗
PubMed1980

Kinetics of rat liver GM2 ganglioside-beta-D-N-acetylhexosaminidase.

The kinetics of beta-D-N-acetylhexosaminidase against GM2 ganglioside were examined. We used a crude preparation of rat liver as the enzyme source because purification of beta-D-N-acetylhexosaminidase results in a decrease in specific activity against GM2 ganglioside. Kinetic plots were not linear but showed a break. At substrate concentrations less than 50 microM the Vmax was 6 pmol GM2 hydrolyzed per hour per micromole 4-MU-GlcNAc hydrolyzed per hour (pmol GM2/mumol 4-MU-GlcNAc) and the Km was 5 microM. At substrate concentrations greater than 50 microM, the Vmax was 7 pmol GM2/mumol 4-MU-GlcNAc and the Km was 14 microM. The critical micelle concentration of GM2 ganglioside was 20-25 microM as determined by spectral shifts of the dye pinacyanol chloride in association with GM2, and 10-15 microM from electrical conductivity measurements which also showed the end of the monomer-micelle transition to occur at 40-50 microM GM2. The increasing excess of micellar substrate at greater than 50 microM GM2 explains the discontinuity in the kinetic plots. Sodium taurocholate had a critical micelle concentration of 9-11 mM using pinacyanol chloride and 2.5-3 mM using electrical conductivity. When included in the assay mixture at a concentration of 10 mM, sodium taurocholate produced a linear kinetic plot. This is probably due to the formation of mixed micelles of detergent and GM2 ganglioside. The Vmax was 200 pmol GM2/MUmol 4-MU-GlcNAc and the Km was 93 microM. The data suggest that ganglioside hydrolysis occurs more readily when the substrate is incorporated into a membrane-like environment.

Animals↗
PubMed1979

Preparation of radiolabeled GM2 and GA2 gangliosides.

GM2 and GA2 gangliosides from the brain of a patient who died of Sandhoff's disease were purified by solvent partition, silicic acid and silica gel column chromatography, and silica gel preparative thin-layer chromatography. They were tritiated in the terminal N-acetylgalactosamine residue using galactose oxidase and sodium [3H]borohydride with the inclusion of catalase and peroxidase into the oxidation reaction. The specific activities were 4.62 X 10(8) dpm/mumol of GM2 ganglioside and 5.54 X 40(7) dpm/mumol of GA2 ganglioside. The addition of catalase and peroxidase to the tritiation procedure is recommended.

Brain Chemistry↗
PubMed1978

[Sensitivity of gonococcus to penicillin G in the canton Berne during the years 1972-1977. Isolation of penicillin-resistant strains].

Since January 1972 Neisseria gonorrhoeae has been systematically investigated by culture techniques at the Institute for Hygiene and Medical Microbiology of the University of Berne. From January 1st 1972 to September 30th 1977, 820 strains were isolated. A survey of the sensitivity of gonococci to penicillin G is presented. We found three groups: 1. 700 sensitive strains (85.4%), 2. 118 strains with decreased sensitivity (14,4%), 3.2 resistant strains (0.2%). The two penicillin-resistant strains are described. Only the patients infected with gonococci of the third group were untreatable with penicillin. In view of the present epidemiological situation penicillin remains the drug of choice. However, bacteriological examination including sensitivity tests is urgently recommended and is absolutely indicated in the event of treatment failures. In addition, culture is necessary to rule out gonorrhea because the asymptomatic form is observed with increasing frequency not only in female patients but recently also in male patients.

Adult↗