Biomedical subjects

B Bjorvatn

Publications and source records attributed to B Bjorvatn.

At least 73 records · Page 4Linked to original sources

PubMed1989

Mechanism of spontaneous loss of heat-stable toxin (STa) production in enterotoxigenic Escherichia coli.

Five strains of enterotoxigenic Escherichia coli (ETEC) showing spontaneous loss of heat-stable enterotoxin (STa) production were studied to elucidate the underlying genetic mechanisms. Southern blot analysis revealed that loss of STa production, and the corresponding lack of hybridization with the STa gene probes, were associated with deletions of DNA fragments harboring the relevant toxin genes rather than with loss of plasmids.

Antigens, Bacterial↗

PubMed1989

Oligonucleotide gene probes may detect enterotoxigenic Escherichia coli directly in fecal smears.

Diarrhoeal stools from 86 Indian children were examined for the presence of enterotoxigenic Escherichia coli (ETEC) by DNA hybridization on bacterial colonies as well as directly on fecal smears. Colony hybridization showed that 8 of the samples contained ETEC. Only in three of these specimens were all the colonies tested positive for ETEC. These samples were correctly identified by the stool smear hybridization assay. The remaining 5 specimens produced enterotoxigenic as well as nonenterotoxigenic colonies. These samples were all negative by the stool smear hybridization technique. Methodological improvements of the stool smear assay may provide a substantially simplified method for the otherwise cumbersome identification of ETEC.

Diarrhea↗

PubMed1988

Onchocerciasis in the Blue Nile Valley of western Ethiopia.

In a survey among 477 inhabitants of the Blue Nile Valley of western Ethiopia 182 (38%) were positive by skin snip investigation for microfilariae of Onchocerca volvulus. Of these only 23% had typical clinical signs and symptoms of onchocerciasis. The highest prevalence rate of microfilariae (84%) was found among Nilotics in the lowlands, where 50% of the children above 10 years, and 90% of adults above 30 years of age, were infected. The mean microfilarial density per skin snip was significantly higher in the high prevalence areas (14) than in the low prevalence areas (3). Positive skin snips from both hip and shoulder were found in 24% of the population, whereas 3% had microfilariae only in the shoulder and 11% only in the hip region. The mean microfilarial density in the hips (16) was double that in the shoulders (8). Ophthalmological evaluation, including slit lamp examination, was possible in 77 of the 182 cases with positive skin snips. Severe eye damage due to onchocerciasis was not observed. However, one 35 year old female had live microfilariae in the anterior chambers of both eyes.

Adolescent↗

PubMed1988

Cloned polynucleotide and synthetic oligonucleotide probes used in colony hybridization are equally efficient in the identification of enterotoxigenic Escherichia coli.

Restriction endonuclease-generated polynucleotide and synthetically produced oligonucleotide gene probes used in colony hybridization assays proved to be efficient for the detection and differentiation of enterotoxigenic Escherichia coli. To compare their relative efficiencies, these two sets of probes were radiolabeled with 32P and were applied to 74 strains of E. coli with known enterotoxin profiles and to 156 previously unexamined E. coli isolates. The enterotoxigenic bacteria Vibrio cholerae O1, Vibrio cholerae non-O1 (NAG), Yersinia enterocolitica, and E. coli harboring the plasmid vectors of the polynucleotide gene probes were examined for further evaluation of probe specificity. The two classes of probes showed a perfect concordance in their specific detection and differentiation of enterotoxigenic E. coli. In the analysis of six strains, the signal strength on autoradiography after hybridization with oligonucleotides was weaker than that obtained after hybridization with polynucleotide probes. The probes did not hybridize with DNA from V. cholerae O1, V. cholerae non-O1 (NAG), or Y. enterocolitica. The strains of E. coli harboring the plasmid vectors of the polynucleotide gene probes were, likewise, negative in the hybridization assays.

Base Sequence↗

PubMed1988

Comparative study of colony hybridization with synthetic oligonucleotide probes and enzyme-linked immunosorbent assay for identification of enterotoxigenic Escherichia coli.

On the basis of the published nucleotide sequences of the genes that code for the heat-labile toxin LTh and the heat-stable toxins STaI and STaII of human enterotoxigenic Escherichia coli, a 34-mer and two 33-mer oligonucleotide probes were synthesized. To compare their relative efficacies in the detection and differentiation of enterotoxigenic E. coli, a colony hybridization technique using these probes and a GM1 ganglioside enzyme-linked immunosorbent assay using monoclonal anti-LT and anti-ST antibodies were used with 76 strains of E. coli with known enterotoxin profiles. For further evaluation of probe specificity, the enterotoxigenic bacteria Vibrio cholerae O1 and non-O1 and Yersinia enterocolitica were examined with the colony hybridization technique. The sensitivity of colony hybridization compared favorably with that of GM1 ganglioside enzyme-linked immunosorbent assay, and the two assays showed a high level of concordance in specific detection and differentiation of E. coli with various enterotoxin profiles (kappa = 0.906, P less than 0.00001). The probes did not hybridize with DNAs from strains of V. cholerae O1 or non-O1 or Y. enterocolitica.

Animals↗

PubMed1988

Genotypes and phenotypes of beta lactamase producing strains of Neisseria gonorrhoeae from African countries.

The phenotypes and genotypes of 26 beta lactamase (penicillinase) producing strains of Neisseria gonorrhoeae (PPNG) from African countries were investigated. Using the restriction enzyme technique nine different restriction enzyme patterns were found, two of them in 15 strains. Of the 26 strains, 16 belonged to serogroup WI (containing protein type IA) and 10 to serogroup WII/III (containing protein IB). Among the IA strains four different serovars were represented, whereas six serovars were found among the IB strains. Five different auxotypes were identified, of which proline requiring (found in 12 strains) and prototrophic (found in 10 strains) dominated. Twelve strains harboured a 4.4 megadalton as well as a 24.5 megadalton plasmid. A 3.2 megadalton plasmid was found in 14 strains, one of which also harboured a 24.5 megadalton plasmid. The 2.8 megadalton cryptic plasmid was present in all 26 strains. The MICs of doxycycline ranged from 0.25 to 2.0 mg/l; the MIC 50% for WI strains was 0.25 mg/l and for WII/WIII strains 1.0 mg/l. A total of 10 different combinations of restriction enzyme pattern, serovar, auxotype, and plasmid were seen in the 16 WI strains compared with eight such combinations in the 10 WII/WIII strains. As expected, the restriction enzyme technique and serological classification gave better differentiation than plasmid profiles and susceptibility to doxycycline. More relevantly, however, these techniques also compared favourably with auxotyping. When the different systems were combined, the sensitivity was greatly increased.

Africa↗

PubMed1988

Genotypic and phenotypic markers in the differentiation of Neisseria gonorrhoeae strains.

Restriction enzyme (RE) patterns, using Hind III enzyme, were analysed on 101 urogenital strains of Neisseria gonorrhoeae. The strains were also analysed serologically, using monoclonal antibodies, and tested for nutritional requirements by auxotyping. In addition, testing susceptibility to doxycycline was performed by an agar-dilution method. The strains were distributed into 23 RE patterns, of which the five most common accounted for 67.3% of all isolates. The same strains were distributed into 17 serovars, of which the four most common accounted for 77.3% of all isolates. Eleven auxotypes were demonstrated, of which the four most common accounted for 85.1% of all isolates. When the methods were combined, 38 combinations of RE patterns and serovars, 25 combinations of RE patterns and auxotypes, and 31 combinations of serovars and auxotypes were seen. Combining all three methods, 40 combinations of RE patterns, serovars and auxotypes were found. Correlations were particularly seen between RE patterns and auxotypes. The strains were moderately sensitive to doxycycline, those with serological markers for WII/WIII being less sensitive than those with markers for WI.

Antibodies, Bacterial↗

PubMed1987

Case fatality of meningococcal disease in western Norway.

In the period 1976-84, 211 patients hospitalized with meningococcal disease were examined for possible relation between various epidemiological parameters and fatality. The peak incidences were in the age groups 0-4 and 13-18 years, with teenage girls peaking 2 years ahead of the boys. The overall case fatality rate was 8.5%. In septicemic patients (without meningitis) hypotension and/or ecchymoses on admission correlated strongly with a poor prognosis. Most deaths occurred during the months of March and November, and none during the summer months. There was a significant clustering of deaths among patients admitted during the morning hours, probably due to delayed diagnosis and treatment during the night. Since almost all patients who died had skin bleedings on admission, frequent examination of the skin in cases with acute unexplained fever might have saved lives.

Adolescent↗

PubMed1987

In vitro evaluation of the activity of Entamoeba histolytica studies on motility.

The tube migration test for leukocyte function studies has been modified to test the motility of Entamoeba histolytica. The test was more sensitive to the effect of antiamebic drugs than was a test for phagocytic activity. A 50% reduction in amebic motility was seen instantly after exposure to metronidazole (40 mg/l). A similar reduction of phagocytosis at the same concentration of the drug was seen only after two hours' preexposure. The extent of amebic migration in the test tube is dependent on factors such as concentration of parasites, temperature and incubation time. The tube migration test is cheap and simple and could be a valuable supplement to existing screening methods for potential antiamebic drugs.

Animals↗

PubMed1986

An outbreak of group B meningococcal disease: tracing the causative strain of Neisseria meningitidis by DNA fingerprinting.

Following an outbreak of meningococcal disease in three schoolchildren in a small community in northern Norway, DNA fingerprinting, serotyping with monoclonal antibodies, serogrouping, and sulfonamide sensitivity testing were applied for characterization and tracing of the causative agent. The three case isolates were genomically indistinguishable, sulfonamide-resistant, serogroup B, serotype 15 meningococci. Throat specimens were collected from 552 healthy contacts, including all children below age 17 and their parents. Among the 36 carrier isolates (carrier rate, 6.5%) 13 showed DNA fingerprints identical, or almost identical, to the index pattern. All of these 13 isolates were sulfonamide resistant, 12 were of serotype 15, and 8 were of polysaccharide serogroup B (5 were nongroupable). These closely related isolates were almost exclusively recovered from schoolchildren of 2 of 15 small villages, one of which included the homes of two of the patients. The remaining 23 carrier isolates were nonresistant, non-type 15 meningococci of widely differing DNA restriction patterns. Our results confirm that DNA fingerprinting has potential as an efficient tool in practical meningococcal epidemiology.

Adolescent↗

PubMed1986

Some phenotypic and genotypic characteristics of prevailing gonococcal strains in northern Norway.

Ninety two non-penicillinase producing Neisseria gonorrhoeae (non-PPNG) strains were investigated by the restriction enzyme technique with Hind III enzyme. Serogrouping by coenzyme. A with monoclonal antibodies and testing susceptibility to doxycycline were also performed by an agar dilution method. Fifteen different restriction enzyme patterns were shown, of which three represented 50% (46/92) of all strains. One band, representing a deoxyribonucleic acid (DNA) fragment of 1.45 kilobase pairs, was shared by all the strains investigated. Serogroup WI dominated, representing 57 isolates (62%) with four serovars, one of which was found in 82% (47/57) of the WI serogroups. Eight serovars were found among WII and WIII serogroups, but no one serovar dominated, as happened among WI serogroups. Identical serovars and restriction enzyme patterns were found in eight patients who were epidemiologically linked. All strains were highly or moderately sensitive to doxycycline, and the strains belonging to serogroup WI were more sensitive than those in the WII or WIII serogroups.

Bacteriological Techniques↗

PubMed1985

Multivariate analysis of Neisseria DNA restriction endonuclease patterns.

Chromosomal DNA was extracted from eleven Neisseria meningitidis and seven Neisseria gonorrhoeae isolates and cleaved with the restriction enzyme HindIII. The DNA fragments were separated according to their size, using a 4% polyacrylamide gel. The band patterns obtained were digitized and statistically analysed by the SIMCA method. To develop the models for N. meningitidis (class 1) and N. gonorrhoeae (class 2), all eleven meningococci and seven gonococci, were used. All strains were classified correctly and showed an extremely good class separation.

DNA Restriction Enzymes↗

PubMed1985

Phenotypic and genotypic characterization of penicillinase-producing strains of Neisseria gonorrhoeae.

Thirty penicillinase-producing Neisseria gonorrhoeae (PPNG) strains, 26 representing 9 serovars of the protein IB and 4 representing 2 serovars of the protein IA serogroup, had 10 different patterns when investigated by the restriction enzyme (RE) technique with Hind III enzyme. One RE pattern dominated, representing 11 strains with 6 different serovars of both the protein IA and IB serogroup. Identical serovars and RE patterns were found among 7 patients (3, 2 and 2, respectively) with positive epidemiology. The majority of the strains (24/30) were resistant to, or showed decreased sensitivity to, doxycycline with minimum inhibitory concentrations between 1 and 8 mg/l, consistent with the Far East origin. All the 30 PPNG strains showed by agarose gel electrophoresis to harbour a 2.8 Mdalton, a 4.4 Mdalton, as well as a 24.5 Mdalton plasmid, whereas the two non-PPNG strains had only the 2.8 Mdalton plasmid.

DNA Restriction Enzymes↗

PubMed1985

Restriction fingerprinting and serology in a small outbreak of B15 meningococcal disease among Norwegian soldiers.

In September 1981 a soldier died from meningococcal septicemia in a military camp in Mid-Norway. Soon afterwards one of his room-mates was transferred to a military camp in Northern-Norway where he shared sleeping quarters (room 7D) with 5 other soldiers of whom 2 fell ill with meningococcal disease 1 month later. Throat cultures were obtained from all 128 soldiers at the military camp in Northern-Norway; 41 (32%) harboured meningococci in their throats. The 3 invasive isolates and the isolates from the 4 healthy carriers at room 7D were all group B and type 15 meningococci. However, by DNA fingerprinting we could identify at least 2, probably 3, different individual strains among these 7 isolates. None of these strains were isolated from soldiers outside room 7D. By use of a B15 whole-bacterium ELISA method we showed that the levels of antimeningococcal IgG antibodies in the sera of the two cases at room 7D were low (18 and 28 OD units) compared with the mean IgG levels in the sera of their 4 healthy room mates (1150 OD units) and the mean IgG in the sera from all healthy soldiers (472 OD units).

Antibodies, Bacterial↗

PubMed1985

Genomic fingerprinting in the epidemiology of gonorrhoea.

We investigated the usefulness of the restriction enzyme (RE) fingerprinting for epidemiological tracing in gonococcal disease. The RE patterns of three paired gonococcal isolates showed corresponding identical fingerprints. Within each of the three pairs of epidemiologically linked isolates the respective restriction patterns were completely identical. Also, the restriction patterns of 6 strains from a larger contact group were identical. Identical restriction patterns were also obtained in each of the two cases where isolates were recovered from both urethra and cervix. The serological findings were in perfect agreement with the genomic fingerprinting as to the identity between all strains of the same epidemiologic chain. Relapse of the original infection could be excluded in one case by the finding of a different RE pattern and also a different serovar pattern of the strain recovered 4 months later.

DNA Restriction Enzymes↗

PubMed1985

Molecular epidemiology of bacterial infections.

This article presents a review of current experience with the restriction enzyme technique in the epidemiology of bacterial infections. It is concluded that this technique has great potential, and that its practical value has been proved under a number of different epidemiologic conditions.

Bacteria↗

PubMed1984

Meningococcal septicaemia treated with combined plasmapheresis and leucapheresis or with blood exchange.

Mortality among patients suffering from meningococcal septicaemia has reached nearly 50% in parts of northern Norway despite intensive care. The activation of complement and blood cells by endotoxin is assumed to be the cause of most of the associated pathophysiological changes. Consequently, it would seem logical to remove such constituents either by combined plasmapheresis and leucapheresis or by blood exchange in patients with a fatal prognosis. Three patients were treated with plasmapheresis and leucapheresis and one with blood exchange. All recovered without sequelae, and no complications or serious problems caused by these procedures were observed. It is concluded that either combined leucapheresis and plasmapheresis or blood exchange is well tolerated and a valuable supplement to conventional intensive care in fulminant meningococcal septicaemia.

Adolescent↗

PubMed1984

Isolates of Neisseria meningitidis from different sites in the same patient: phenotypic and genomic studies, with special reference to adherence, piliation, and DNA restriction endonuclease pattern.

Neisseria meningitidis was isolated from the throat, blood, and cerebrospinal fluid of six patients and from the throat and blood of two patients. All 22 isolates were of serogroup B, serotype 15, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis type IV. Isolates from a single patient always possessed identical DNA restriction endonuclease patterns; this observation strongly suggested genomic identity. In spite of this apparent genomic identity, however, significant differences in piliation and adherence were observed among isolates from different sites in the same patient. Isolates from the throat were significantly more piliated (P less than .001) and adhered to human buccal epithelial cells in vitro in significantly higher numbers (P less than .001) than did isolates from the blood and the cerebrospinal fluid of the same patient. These results indicate that phase shift occurs in N. meningitidis in vivo.

Adhesiveness↗