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Biomedical subjects

P Haas

Publications and source records attributed to P Haas.

At least 19 recordsLinked to original sources
PubMed1998

Disseminated feline leishmaniosis due to Leishmania infantum in Southern France.

A fortuitously discovered case of feline leishmaniosis is reported. The parasites were found in the skin and the bone marrow of a domestic female cat that spontaneously died after a few weeks of evolution. Serological tests for FeLV, FIV and PIF virus detection gave negative results. By using Western blot serology, a characteristic pattern of leishmaniosis was obtained and by performing an isoenzyme electrophoresis, a Leishmania infantum MON-1 strain was identified. The same zymodeme is implicated in most of the canine and human leishmaniosis in Southern Europe. A study on the prevalence of asymptomatic feline leismaniosis is foreseen.

Animals↗
PubMed1998

Studies on the effect of the solvents dimethylsulfoxide and ethyleneglycoldimethylether on the mutagenicity of four types of diisocyanates in the Salmonella/microsome test.

The mutagenicity of isomers and homologs of diphenylmethanediisocyanate (4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane, a mixture of monomeric MDI isomers, and polymeric MDI), containing 55-100% of monomeric MDI, was determined in the Salmonella/microsome test using dimethylsulfoxide (DMSO) and ethyleneglycoldimethylether (EGDE) as solvents. Positive results were obtained for DMSO solutions of all four diisocyanates in the presence of S9 mix containing 30% S9 fraction. Uniformly negative results were found when the diisocyanates were dissolved in EDGE. These results correspond to those of analytical investigations. A small amount of diaminodiphenylmethane (MDA) is one of the reaction products formed when MDI is dissolved in commercial DMSO. No MDA could be detected in solutions of MDI in EGDE. It is therefore concluded that the positive results obtained with diisocyanates in DMSO solutions are due to the formation of MDA. This is artificially formed through the hydrolysis of MDI, caused by traces of water that are always present in DMSO. These findings indicate that DMSO is an inappropriate solvent and should therefore not be used in any in vitro study with diisocyanates. EGDE may be a suitable replacement. The positive test results reported so far for DMSO solutions of MDI are thus only of limited relevance for risk evaluation.

Dimethyl Sulfoxide↗
PubMed1996

Effect of transmembrane helix packing on tryptophan and tyrosine environments in detergent-solubilized bacterio-opsin.

Bacterio-opsin (bO) is folded in a nearly native conformation in mixed micelles of dimyristoyl phosphatidyl choline (DMPC) and 3-[(3-cholamidopropyl)-dimehtylamonio]-1-propane sulfonic acid (CHAPS), but bO is partially unfolded in sodium dodecyl sulfate (SDS). UV difference spectroscopy was used to study the changes in environment of bO aromatic amino acid side chains that occur upon partial unfolding. The UV difference spectra of peptides in CHAPS/DMPC minus peptides in SDS were measured for bO and the following subfragments of bO: C1 (residues 72-248), C2 (1-71), V1 (1-166), V2 (167-248), CB7 (119-145), CB9 (164-209), and CB10 (72-118). The spectra show that, in partially unfolded bO in SDS, the Tyr and Trp absorbance is blue-shifted. The difference spectra were compared to solvent perturbation difference spectra of N-acetyl-L-tyrosine ethyl ester and N-acetyl-L-tryptophanamide. The exposure change calculated from the difference spectra was found to correlate with the change in the number of van der Waals contacting atoms upon partial unfolding, and also with the number of transmembrane helical segments. This result suggests a simple experimental method of testing helix packing arrangements derived from hydropathy plots and model building.

Amino Acid Sequence↗
PubMed1995

Immunoprinting excludes many potential susceptibility genes as predisposing to early onset pauciarticular juvenile chronic arthritis except HLA class II and TNF.

DNA profiles (immunoprints) were generated for 120 patients suffering from early onset pauciarticular chronic arthritis (EOPA-JCA) and > 500 healthy controls utilizing highly polymorphic microsatellites in the vicinity of immunorelevant genes. Six T cell receptor (TCR) markers for the CD3D, TCRDVAJ, TEA, TCRBV6S1, BV6S3, BV6S7 and BV13S2 genes were analysed. Furthermore markers for the cell surface molecule CD40L, for cytokine genes (IL-1A, IL-2, IFN-alpha, FGF-alpha, TNF-alpha), the chromosomal region of the IRF2 and the cytokine receptor gene IL5RA were studied as well as two polymorphisms within the promotor region of the TNF-alpha gene. Coding region polymorphisms were evidenced indirectly by repeat length variation or they were predicted from the microsatellite distribution profiles and then confirmed by direct sequence analysis. Statistical evaluations were performed with respect to known predispositions, predominance of females (> 80%) and HLA-DR and -DQ haplotypes. Cell surface molecules (TCR, CD40L, IL5RA) as well as almost all cytokines (IL-1A, IFN alpha, FGFA, IRF2 region) were excluded as predisposing in our JCA panel. The TNF-alpha microsatellite alleles (GT)10-12 contribute considerably to manifestation of the disease, in HLA-DRB1*11(12) individuals (RR = 12.8). The TNF-alpha allele is not found in linkage disequilibrium with HLA-DRB1*11(12) and may be present on either chromosome 6. Thus, a novel susceptibility factor probably within the TNFA/TNFB gene region has been identified via linkage with the TNF-alpha microsatellite allele. Apparently complex compositions of the genetic background rather than single genes provide the precondition for manifestation of the autoimmune disease EOPA-JCA. Immunoprinting unravels the variability of the immunological genome via the semi-directed microsatellite approach efficiently.

Age of Onset↗
PubMed1995

A subgroup of LHRH neurons in guinea pigs with progestin receptors is centrally positioned within the total population of LHRH neurons.

Although the role of gonadal steroids in inducing the LH surge is undisputed, the mechanism(s) whereby steroids induce the release of the hypothalamic luteinizing hormone-releasing hormone (LHRH) remain(s) enigmatic. In this study we examined the issue of the presence of steroid receptors in LHRH neurons using a mammalian species that has a true luteal phase, namely, guinea pigs. Progestin receptors (PR) were localized in LHRH neurons of ovariectomized guinea pigs administered estradiol (10-20 micrograms estradiol benzoate) for 3-4 days, using several different immunocytochemical protocols. The subgroup of LHRH neurons containing PR, although small, was strategically positioned within the core of the total population of LHRH neurons. This central position was visualized in simultaneous views of three-dimensional computer reconstructions of the populations of LHRH/PR neurons and LHRH neurons. The subgroup of LHRH/PR neurons formed a thread permeating the population of LHRH neurons. We propose that in guinea pigs, LHRH neurons containing progestin receptors, are foci of activity, capable of activating a larger component of the LHRH population of cells in certain endocrine conditions, such as prior to the LH surge.

Animals↗
PubMed1993

Popliteal arteriovenous fistula after corrective upper tibial osteotomy.

Injuries to the popliteal artery or vein are rare complications of knee arthroscopy or osteosynthesis at the distal femur or the proximal tibia. We report a case of iatrogenic arteriovenous fistula after proximal tibial osteotomy for varus deformity. A 71-year-old woman complained of pain and swelling of the foot 9 weeks after a corrective barrel-vault osteotomy of the left tibia. Angiography demonstrated an arteriovenous fistula between the popliteal vessels due to osteotomy of the tibial head. The fistula was separated and popliteal vessels closed by continuous suture and a small saphenous vein patch.

Aged↗
PubMed1993

Polymorphism of the 5' flanking region of the HLA-DQA1 gene in coeliac disease.

Coeliac disease (CD) is associated with particular HLA genotypes. The susceptibility gene (or genes) has been mapped to the class II region, most probably to the DQ loci. Polymorphism of the upstream promoter region of the DQA1 gene (QAP) has been recently reported. At least ten variants or QAP alleles have been found, some of which are present in the cis-acting regulatory sequences. Allelic differences in DQ molecule expression may play a role in susceptibility to CD. We investigated the QAP polymorphism in 102 CD patients and 142 unrelated healthy controls of Czech origin using polymerase chain reaction amplification (PCR) of genomic DNA and oligonucleotide probes. We found a significant frequency increase of the alleles QAP 4.1 (RR = 10.3, p.c. = 10(-6) and QAP 2.1 (RR = 2.4, p.c. = 0.017) in patients over controls. An increased susceptibility is provided by the presence of both alleles, as is shown by the higher proportion of QAP 4.1, 2.1 heterozygotes among patients than expected from the Hardy-Weinberg equilibrium and by the comparison of the odds ratios for these alleles. There is a strong linkage disequilibrium between the QAP alleles and the DQA1, DQB1, and DRB1 loci. Two haplotypes carrying the QAP alleles whose frequency is increased are predominant in this group of CD patients: DQB1*0201, DQA1*0501, QAP4.1, DRB1*0301 and DQB1*0201, DQA1*0201, QAP 2.1, DRB1* 0701. Thus, the QAP variants are increased as part of these haplotypes and we cannot discriminate if they are responsible for the primary association.

Alleles↗
PubMed1993

[Observations on pathophysiology and pathogenesis of venous thrombosis].

Even today, Virchow's triad is still a useful method for describing the circumstances under which thrombosis can occur. To investigate the underlying pathophysiological principles, however, the methods must differentiate more clearly. Only recently, the complicated interactions of blood coagulation and fibrinolysis have been described. Although detailed determinations of markers of activated coagulation and fibrinolysis can be performed, it has not been possible to achieve a reliable screening method to indicate the individual patient's risk. Alterations in the endothelial cells seem to play a key role in thrombogenesis. The clinician's interest in thrombosis research is based on several open or insufficiently answered questions, such as why thrombosis can occur in veins for away from the site of the operation, whether reliable and simple screening methods can be established in order to determine the patient's risk constellation, and how the methods of preventing thrombosis and administering therapy can be improved.

Blood Coagulation↗
PubMed1992

[Phlebotomus perniciosus Newstead, 1911 naturally infected by promastigotes in the region of Nice (France)].

The authors report the results of investigations in Nice from July, 16 to August, 3, 1991. The 2,098 phlebotomes captured represent three species: Phlebotomus perniciosus, Phlebotomus ariasi and Sergentomyia minuta. Two species: P. perniciosus and P. ariasi are infected with promastigotes. About 4% of dissected females are parasited. This is the first description in France of P. perniciosus infected.

Animals↗
PubMed1990

Regeneration of bacteriorhodopsin in mixed micelles.

Regeneration of bacteriorhodopsin from bacterioopsin and all-trans-retinal was studied in a mixed micelle system consisting of dodecyl sulfate, CHAPS and a water-soluble phospholipid dihexanoylphosphatidylcholine (hex2-PhosChol). Regeneration to approximately 40,000 M-1.cm-1 extinction at 550 nm (epsilon 550) was obtained with either 2.3 mM or 6.5 mM CHAPS along with 6.9 mM dodecyl sulfate and 4.5 mM hex2-PhosChol in 0.16 M NaCl and 40 mM phosphate (pH 6.0). Without CHAPS, the regeneration in 4.5 mM Hex2-PhosChol gave epsilon 555 = 27,800; without PhosChol, the 1:3 CHAPS/dodecyl sulfate mixture gave epsilon 550 approximately 20,000; and without PhosChol the nearly equimolar CHAPS/dodecyl sulfate mixture gave epsilon 550 approximately 10,000. The composition of the mixed micelles was estimated from fluorescence spectroscopy using pyrene butyryl hydrazine. The molecular weight was estimated by molecular seive chromatography to be 87,100 for 2.3 mM CHAPS, 6.9 mM dodecyl sulfate and 0.67 mM hex2-PhosChol; and 83,200 for 7.0 mM CHAPS, 6.9 mM dodecyl sulfate, and 1.1 mM hex2-PhosChol. These results are consistent with the idea that at low concentrations of CHAPS and dodecyl sulfate, CHAPS organizes the dodecyl sulfate into disk shaped bilayer micelles that are favorable for bacterioopsin refolding. However, a high concentration of either detergent inhibits regeneration. Added hex2-PhosChol can overcome the inhibitory effects of high concentrations of either CHAPS or dodecyl sulfate.

Bacteriorhodopsins↗
PubMed1990

Synthesis of human coagulation factor XIII in yeast.

The active form of coagulation factor XIII, factor XIIIa, is a transglutaminase that covalently cross-links fibrin molecules by joining gamma-glutamyl and epsilon-lysyl primary amino groups. In this paper we report the design of a yeast expression vector called pPH3 which includes the GAL1-GAL10 promoter, multiple cloning sites, the URA3 selectable marker, the 2 mu sequences and the ampicillin-resistance gene. We have placed full-length factor XIII cDNA into the PstI site of this vector, transformed the yeast cells and expressed human coagulation factor XIII which was found to be enzymatically active based on observations that this recombinant factor XIII: (a) showed immunological identity with placental factor XIII; (b) was demonstrated to have transglutaminase activity, and (c) cross-linked fibrin in a manner identical to human placental factor XIIIa-catalyzed polymerization (gamma-gamma dimerization and alpha polymerization).

Blotting, Northern↗