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Biomedical subjects

M Labuda

Publications and source records attributed to M Labuda.

At least 73 records · Page 4Linked to original sources
PubMed1992

Two hereditary defects related to vitamin D metabolism map to the same region of human chromosome 12q13-14.

We have localized the locus for the vitamin D receptor (VDR) responsible for hypocalcemic vitamin D-resistant rickets (HVDRR), close to the pseudovitamin D-deficient rickets (PDDR) locus, another disorder related to impaired vitamin D metabolism. PDDR (formerly vitamin D dependency type I, VDD1) was recently mapped to human chromosome 12q14 by linkage analysis. Here we report on the assignment of VDR to 12q13-14 by in situ hybridization and by linkage analysis. Linkage analysis between VDR, PDDR, and several RFLP markers show close linkage, with no recombination (theta = 0) between VDR and PDDR (Z = 1.94), a COL2A1 haplotype (Z = 4.03), ELA1 (Z = 0.98), and D12S15 (Z = 4.17). The analysis of extended haplotypes in one of the PDDR families provides evidence for recombination between VDR and PDDR and localizes VDR together with COL2A1 proximal to PDDR. Complete allelic association detected between VDR and COL2A1 loci on PDDR chromosomes and lower association between VDR and PDDR suggests a VDR location very close to COL2A1 and one more distant to PDDR. We propose the following order of loci: (VDR, COL2A1), (PDDR, ELA1, D12S15), D12S4, (D12S14, D12S17), D12S6. Thus, two clearly distinct loci involved in the control of vitamin D activity map close to each other in the region 12q13-14.

Chromosomes, Human, Pair 12↗
PubMed1991

Arthropod vectors in the evolution of bunyaviruses.

Viruses from each genus of Bunyaviridae have preferential relationships to the arthropods of only one or two families, i.e. Bunyavirus to mosquitoes (Culicidae), Phlebovirus to sand flies (Psychodidae) and mosquitoes, Uukuvirus and Nairovirus to ticks (Ixodidae and Argasidae). An exception is genus Hantavirus not proven to be transmitted by vectors. Within the Bunyavirus genus 16 serogroups have been recognized on the basis of their antigenic relationship. Based on isolations from the nature each serogroup is preferentially linked with arthropod species (mostly mosquitoes) of one, or two genera. For 8 out of 16 serogroups Culex mosquitoes are the main insect vectors. Two serogroups are linked with Aedes mosquitoes, three with Anopheles mosquitoes. Aedeomyia mosquitoes, Culicoides bitting miges and Hyalomma ticks are vectors of one serogroup each. Evolutionary trends within the genus Bunyavirus and within the family Bunyaviridae can be recognized based on relationships of bunyaviruses to their arthropod vectors.

Animals↗
PubMed1991

Vertical and venereal transmission of California group viruses by Aedes triseriatus and Culiseta inornata mosquitoes.

Aedes triseriatus and Culiseta inornata mosquitoes were compared in their ability to transmit vertically La Crosse (LAC) and snowshoe hare (SSH) viruses. LAC virus was transovarially transmitted by 53% of Ae. triseriatus, the natural vector, and by 22% of Cs. inornata mosquitoes. SSH virus was transovarially transmitted by 89% of Cs. inornata, a proposed natural vector, and by 29% of Ae. triseriatus. A genetic approach, using LAC, SSH, and LAC/SSH reassortant viruses was then used to elucidate viral genetic determinants of transovarial transmission of bunyaviruses by Ae. triseriatus mosquitoes. Viruses containing the LAC medium sized (M) RNA segment were most efficiently transovarially transmitted by Ae. triseriatus mosquitoes. LAC, SSH, and Tahyna (TAH) viruses were compared in their ability to be venerally transmitted. All three viruses replicated in the reproductive tract of male Aedes triseriatus and were venereally transmitted to female mosquitoes. LAC and TAH viruses infected previously blood fed (BF) but not non-blood fed (NBF) Aedes triseriatus female mosquitoes.

Aedes↗
PubMed1991

Interference between the viruses of tick-borne encephalitis complex in the Ixodes ricinus ticks.

The interference of two closely related viruses of the tick-borne encephalitis complex (TBE) in Ixodes ricinus ticks has been observed. 42.9 to 65.0% of dually infested ticks developed virus neutralization antibodies in mice without signs of illness, which contrasts with the control ticks infected with 198 strain only. Other explanations of this interference could include alteration of viral receptors on host cells or induction of antiviral activity in the infected ticks and/or other vectors such as mosquitoes.

Animals↗
PubMed1990

Mapping autosomal recessive vitamin D dependency type I to chromosome 12q14 by linkage analysis.

Linkage analysis in French-Canadian families with vitamin D dependency type I (VDD1) demonstrated that the gene responsible for the disease is linked to polymorphic RFLP markers in the 12q14 region. We studied 76 subjects in 14 sibships which included 17 affected individuals and 17 obligate heterozygotes. Significant results for linkage were obtained with the D12S17 locus at the male recombination fraction (theta m) .018 (Z[theta m theta f] = 3.20) and with D126 at (theta m = .025 (Z[theta m theta f] = 3.07). Multipoint linkage analysis and studies of haplotypes and recombinants strongly suggest the localization of the VDD1 locus between the collagen type II alpha 1 (COL2A1) locus and clustered loci D12S14, D12S17, and D12S6, which segregate as a three-marker haplotype. Linkage disequilibrium between VDD1 and this three-marker haplotype supports the notion of a founder effect in the studied population. The current status of the localization of the disease allows for carrier detection in the families at risk.

Chromosome Banding↗
PubMed1990

Dual infection of Ixodes ricinus ticks with two viruses of the tick-borne encephalitis complex.

Ixodes ricinus female ticks were inoculated with Skalica (SK) virus (non-pathogenic for adult albino mice by subcutaneous route) and 14 days later they were challenged with strain 198 of Tick-borne Encephalitis (TBE) virus (highly pathogenic for adult albino mice by subcutaneous route). After additional 14 days of incubation, 42.9 to 65.0% of the adult (10-12 g) albino mice infested with these double infected ticks developed antibodies to TBE without signs of sickness (transmission of SK virus), while paralysis or death was registered in 35.0 to 57.1% of infested mice (transmission of strain 198) depending on the concentration of strain 198 used for inoculation of ticks. However, a low degree of interference to superinfection with strain 198 was observed, when the dissected tick salivary glands were examined by subcutaneous inoculation of adult albino mice (more than 90% of examined salivary glands contained strain 198 virus).

Animals↗
PubMed1990

Longitudinal study of natural foci of Central European encephalitis virus in West Slovakia.

A total of 2922 small terrestrial mammals of 12 species were collected in six localities of West Slovakia between 1981 and 1986. When examined for the prevalence of neutralizing antibodies (NA) to Central European encephalitis (CEE) virus we found that 14.6% had antibody. Nearly all (97%) of the 426 animals with antibody were Clethrionomys glareolus, the most abundant species (52.6% of mammals collected, 15.1% of those with antibody). Apodemus flavicollis (22.5% of mammals collected, 18.1% of those with antibody), Apodemus sylvaticus (14% of mammals collected, 8.5% of those with antibody), and Microtus arvalis (5.5% of mammals collected, 3.3% of those with antibody). In all locations studies the most abundant tick found on small mammals was Ixodes ricinus (larvae and nymphs). Less abundant, but present in all studied sites, were larvae and nymphs of Dermacentor reticulatus and Haemaphysalis concinna. Six strains of CEE virus were isolated from tissues of animals: four from Clethryonomys glareolus and one each from Apodemus flavicollis and Sorex araneus. Three of six isolates were from animals collected in February; none of the six had detectable neutralizing antibody to CEE virus. We discuss these observations with regard to possible mechanisms of persistence of CEE virus.

Animals↗
PubMed1989

Amplification of arbovirus transmission by mosquito intradermal probing and interrupted feeding.

Probing is the crucial phase for the successful intake of the blood by a mosquito female, saliva being ejected during the intradermal probing period. When Tahyna virus (California group, family Bunyaviridae) carrying and transmitting Aedes aegypti mosquito was allowed to feed on 3 suckling white mice for 4 hr, 66.7% of the 162 exposed mice became infected. When one infected mosquito was put in contact with 5 mice, 53.6% of the 250 exposed mice became infected. Multiple transmission of the virus to the available hosts during completion of one blood meal by a single mosquito has been demonstrated.

Aedes↗
PubMed1989

[Long-term results of surgical treatment of portal hypertension].

Large number of contradictory operative surgeries refer best to embarrasments, existed on this section of surgery. Today, from the amount of operative surgeries prevail the endoscopic sclerotization of the gastroesophageal varices. On basis of retrospective study of 48 portosystemic shunts was showed, that 28 operated patients survive average 8.1 year, till now 4 patients of them are alive, within 8-14 years. In 7 cases of azygoportal deconexion by Torres-Dengi, average time of survive was 2.5 year. There experiences led the authors to elaborate an algorithm of treatment of portal hypertension, where the postosystemic shunts are the portosystemic shunts are the effective palliative operative surgery in indicated cases.

Esophageal and Gastric Varices↗
PubMed1986

Serological survey with the antigen of haemorrhagic fever virus with renal syndrome in small rodents in Slovakia.

Results of serological survey in small rodents with the antigen of haemorrhagic fever with renal syndrome (HFRS) virus indicate the existence of a natural focus of this virus in Slovakia. Antibodies were found in the following free-living rodent species: Clethrionomys glareolus, Apodemus agrarius, Apodemus sylvaticus, Pitymys subterraneus, Microtus arvalis and Microtus economus. A total 10 out of 120 (8.2%) small rodents trapped in investigated localities of Western and Eastern Slovakia had antibodies to the HFRS virus antigen as detected by complement fixation (CF) and/or immunofluorescence (IF) tests.

Animals↗
PubMed1985

Variations of four Aedes aegypti mosquito strains in their susceptibility to and transmissibility of Tahyna virus.

Aedes aegypti mosquitoes originating from different colonies were infected with Tahyna virus by sucking on viraemic newborn mice (peak titre 10(2) X 5 mouse i.c. LD50/0.01 ml). The mosquitoes of laboratory strain "London" proved most susceptible (infection rate 74.2%, transmission rate 60%), while mosquitoes of the laboratory strain "Basel" and strain "Bangkok" (Southeast Asia) were less susceptible (infection rate 23.7 and 17.6%, respectively, transmission rate 6.0 and 10.0%, respectively). Mosquitoes of "Ifakara" strain (East Africa) were found resistant to Tahyna virus infection.

Aedes↗
PubMed1984

Haemorrhagic fever virus with renal syndrome in small rodents in Czechoslovakia.

The antigen of haemorrhagic fever with renal syndrome (HFRS) was detected in the lungs of the following free-living small rodents trapped in different localities in Eastern Slovakia: Clethrionomys glareolus (2 positive samples of 7), Apodemus flavicollis (1 sample of 24) and Apodemus agrarius (7 positive samples of 66). The virus was first identified by indirect fluorescent antibody (FA) staining using human convalescent serum from a case of epidemic nephropathy (NE) of Scandinavia. The lung suspensions selected according to positive immunofluorescence were inoculated by intramuscular (i.m.) route into suckling rats; the antigen prepared from the lungs of these rats by sucrose-acetone extraction reacted with the prototype human serum in complement-fixation (CF) reaction. The results of the latter assay were in good agreement with those of the indirect FA staining.

Animals↗
PubMed1983

Experimental model of transovarial transmission of Tahyna virus in Aedes aegypti mosquitoes.

The progeny of 31 viruliferous Aedes aegypti females infected with Tahyna virus by sucking on viraemic newborn mice was investigated for virus presence. Out of 1587 individuals of the F1 generation, 16 suspensions representing the progeny of 7 females were positive in 146 trials. Individuals of the F1 generation failed to transfer the virus by sucking. Electron microscopy revealed the presence of Tahyna virus particles in the cytoplasm of maturing oocytes inevitably confirming the transovarial transfer of the virus by germinal cells of Aedes aegypti mosquitoes.

Aedes↗