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Biomedical subjects

A Novak

Publications and source records attributed to A Novak.

At least 19 recordsLinked to original sources
PubMed1992

Four conserved cysteine residues are required for the DNA binding activity of nuclear factor I.

The role of Cys residues in the site-specific DNA binding activity of the nuclear factor I (NFI) family of proteins was assessed by chemical modification and site-specific mutagenesis. Treatment with the thio-specific reagent N-ethylmaleimide abolished site-specific DNA binding of all forms of NFI present in HeLa nuclear extracts. Preincubation of cell extracts with an oligonucleotide containing an NFI-binding site provided partial protection of NFI from N-ethylmaleimide inactivation. Mutations were made in the cDNA encoding a truncated form of the NFI-C/CAAT box transcription factor-1 protein, converting each of the five Cys residues in the DNA-binding domain of the protein into Ser residues. NFI-C proteins containing mutations in any of four conserved Cys residues, expressed in Escherichia coli or in vitro, did not bind to DNA. NFI-C with a mutation in a nonconserved Cys residue had normal DNA binding activity. Both this active mutant and wild-type NFI-C protein were inactivated by modification of their sulfhydryl residues with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), and preincubation with an oligonucleotide containing an NFI-binding site gave partial protection against inactivation. After modification with DTNB, DNA binding activity was partially restored by subsequent incubation with dithiothreitol, indicating that inactivation of NFI by DTNB was reversible. These studies indicate an essential role for free sulfhydryl residues in NFI-DNA binding.

Amino Acid Sequence↗
PubMed1992

Two karyotypically unrelated clones with the t(5;17) and deletion of 5q in myelodysplastic syndrome.

We report a patient with primary myelodysplastic syndrome (MDS) and two coexisting karyotypically independent clones. Cytogenetic investigation of bone marrow (BM) cells at diagnosis showed, besides the cells with normal karyotype, a clone that manifests an interstitial deletion of the long arm of chromosome 5 and a second one with a t(5;17). The rarity of finding a BM mosaicism in myelodysplasia with 5q- in some cells and different chromosomal abnormalities in others may be considered to support the multistep theory of pathogenesis in MDS.

Adult↗
PubMed1992

Diagnostic possibilities of ERA in developmental speech disorders.

The differential diagnosis of developmental speech disorders may be very difficult. We tried to differentiate between the developmental dysphasia and dysarthria by means of CERA, using the different kinds of stimuli--tone bursts, words and white noise. The BERA was performed using the filtered clicks as stimuli. We have found the responses to tone, verbal and noise stimuli in children with developmental dysarthria. The latency times were prolonged to verbal and noise stimuli. We did not find any responses to verbal and noise stimuli in children with developmental dysphasia. At the BERA investigation we did not find the auditory evoked brainstem responses in children with developmental dysarthria on the side of motoric innervation lesion. The latency times of waves N3 and N5 were prolonged in children with developmental dysphasia. The CERA and BERA seems to be a good differential diagnostic tool for differentiation between these two kinds of developmental speech disorders. The results confirmed also that there are the mixed forms of those developmental speech disorders.

Aphasia↗
PubMed1991

[Diagnostic characteristics of the CA-50 and CA 72-4 tumor markers in body fluids. Use in the diagnosis of malignant effusions].

The paper presents the results of a comparative investigation of CA-50 and CA 72-4 in the serum and effusions of the control group and a group of patients with various localizations of malignant tumors. The diagnostic applicability of CA-50 in the serum is limited by a substantial extent of falsely positive results, which is not the case with CA 72-4. Malignant cells make a more intensive release of CA 72-4 into effusions than into the blood, and the situation with CA-50 is reverse. It has been established that CA-50 in the serum and that CA 72-4 in effusions are complementary parameters. Markers in effusions have more favorable diagnostic characteristics in relation to serum. Although CA 72-4 is of a more superior diagnostic reliability, the examining of both markers is of help in the differentiation of benign peritoneal and pleural effusions from the malignant ones. The persistence of these markers in body fluids does not indicate the primary origin of malignant tumors.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1990

Chemosensitivity of fine afferents from rat skin in vitro.

1. Properties of sensory receptors with slowly conducting nerve fibers (less than 10 m/s) were studied using a rat skin-saphenous nerve in vitro preparation where receptive fields of identified single units can be isolated and superfused at the corium side with defined chemical solutions. 2. With mechanical search stimuli, 150 slowly adapting units were identified, 88% C-fibers, and the remainder, A delta-fibers. The majority of these units (65%) were categorized as mechano-heat sensitive ("polymodal") with controlled radiant heat stimulation. The remaining units were classified as low- or high-threshold mechanoreceptors according to their von Frey thresholds. 3. Bradykinin (BK), in concentrations of 10(-8) to 10(-4) M, was repeatedly applied for 1 min at 10-min intervals. Fifty-six percent of the polymodal C-fibers responded to BK (up to 10(-5) M), in contrast to 17% of the heat-insensitive units (P less than 0.01). No correlation between BK sensitivity and conduction velocity or von Frey threshold was found. 4. The BK "threshold concentrations" to excite C- and A delta-fibers were about equally distributed over a range from 10(-8) to 10(-5) M. 5. There was a large interindividual variability in pattern and magnitude of the response to BK. Intraindividually, a marked tachyphylaxis upon repeated BK stimulation was observed. 6. In fibers with a slow development of tachyphylaxis, the effects of conditioning application of different chemicals on BK responsiveness were studied. Norepinephrine in 10(-7) M concentration did not produce a significant effect, whereas 10(-5) M and 10(-4) M seemed to increase the BK responses. 7. Prostaglandin E2 (10(-6) M) caused a weak sensitization to BK on average (n.s.), but serotonin (10(-6) M) was clearly effective (P less than 0.05). 8. The strongest sensitization to BK (P = 0.01) resulted from conditioning heat stimulation, which also uncovered a responsiveness in some units initially insensitive to BK. 9. In some experiments the calcium concentration in the superfusate of receptive fields was lowered to 0.3 mM, which induced ongoing activity in C-fibers and markedly increased the BK responses in two polymodal units tested. Increasing the calcium concentration to 3.0 mM reversed these effects. 10. After completing the BK test protocol, polymodal C-fibers were exposed to other chemicals.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1989

Chronic myeloid leukemia associated with pure red cell aplasia and terminating in promyelocytic transformation.

After intermittent treatment with busulphan over a 7-year period for chronic myeloid leukemia (CML) in chronic phase, a 39-year-old female developed leukocytosis in association with pure red cell aplasia (PRCA). Bone marrow examination confirmed erythroid aplasia, and culture revealed a total absence of erythroid progenitor cells. The patient then was treated with azathioprine, corticosteroids, cyclophosphamide, plasma exchange, and cyclosporin A, but she remained erythroblastopenic and transfusion dependent for more than a year, at which time a promyelocytic transformation supervened. The authors propose that this sequence of events, hitherto unreported, is a manifestation of the multistep progression of CML.

Adult↗
PubMed1988

[Septic melioidosis following a visit to India].

A case is reported of lethal septicemic melioidosis due to Pseudomonas pseudomallei in a 40-year-old woman who had been in India. The epidemiology, clinical findings and management of this unusual disease are discussed. The diagnostic value of serological tests and in vitro sensitivity of Pseudomonas pseudomallei to various antibiotics are outlined. Melioidosis should be considered in the differential diagnosis of any febrile condition in a person returning from a tropical country.

Adult↗
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↗
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↗