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Biomedical subjects

R Claus

Publications and source records attributed to R Claus.

At least 55 records · Page 3Linked to original sources
PubMed1994

In vitro effects of solubilized HLA-DR--role in immunoregulation?

To test the hypothesis that soluble HLA-DR antigens (sHLA-DR), binding to the T-cell receptor (TCR) and/or CD4 structures, compete with and abrogate functions of their cell-bound counterparts, we studied effects of detergent-solubilized, affinity-purified HLA-DR molecules on the DNA synthesis, IL-2, and IL-1 secretion by human peripheral blood mononuclear cells (PBMC). While resting T cells did not show any response, there was a dose-dependent suppression of T-cell responses induced by mitogen (phytohemagglutinin, PHA), recall antigen (purified protein derivative of tuberculin, PPD), or HLA class II alloantigens (Daudi cells). In the PHA system, sHLA-DR affected DR-identical and DR-disparate PBMC with equal efficiency, suggesting a nonspecific interference with accessory functions of cell-bound HLA class II molecules. A competitive ligation of lymphocyte (rather than of monocyte) CD4 is suggested based on the failure of sHLA-DR (i) to potentiate inhibitory effects of anti-CD4 mAb, (ii) to suppress mitogen responses after depletion of CD4+ lymphocytes and also following separate monocyte (vs lymphocyte) pretreatment, and (iii) to induce a reproducible IL-1 secretion inhibition. In the PPD system, suppressive sHLA-DR effects on autologous or DR-identical PBMC significantly exceeded that on DR-disparate PBMC, and in the MLR, third party allogeneic sHLA-DR was exceeded in its suppressive potency both by sHLA-DA pertinent to responder cells and by sHLA-DR pertinent to stimulator cells. These additional specific effects may result from competition (with cell-bound class II restriction and recognition determinants) at the TCR level rather than from peptide competition at the antigen-presenting cell level. Interference by sHLA-DR with the primary and/or accessory signaling may offer new therapeutic strategies in allotransplantation and autoimmunity.

Dose-Response Relationship, Drug↗
PubMed1994

Quantitation of soluble HLA-DR antigens in human serum and other body fluids.

The existence of soluble forms of MHC class II molecules is well established. To quantify soluble HLA-DR antigens (sHLA-DR) in human serum and other body fluids, we developed an enzyme immunoassay using two non-overlapping HLA-DR-specific monoclonal antibodies (RoDR, BL-la/5) and an immunoaffinity chromatography-purified sHLA-DR standard. In serum of healthy individuals, sHLA-DR levels were found in the range between 0.6 and 3 ng/ml (median 0.85 ng/ml) whereas EDTA plasma samples showed concentrations about 20 times higher (median 21 ng/ml). In tears, saliva, sweat, urine, amniotic fluid, cerebrospinal fluid, and bronchoalveolar lavage, sHLA-DR could also be detected. No association was found between sHLA-DR serum levels and distinct HLA specificities. In the sera of patients with autoimmune diseases, slightly enhanced sHLA-DR values were found (juvenile rheumatoid arthritis: median 2.0 ng/ml, lupus erythematosus: 1.5 ng/ml, diabetes mellitus: 2.1 ng/ml).

Amniotic Fluid↗
PubMed1993

High-performance liquid chromatographic method for the determination of 3-methylindole (skatole) and indole in adipose tissue of pigs.

A rapid method for the determination of skatole (3-methylindole) and indole in adipose tissue of pigs by reversed-phase high-performance liquid chromatography has been developed. Tissue samples were melted in a microwave oven, and 100 microliters of the liquid fat were dissolved in 1 ml of n-hexane and extracted with acetonitrile-water (75:25, v/v). Portions of 100 microliters of the solution were used for chromatographic analysis. Elution was performed on a reversed-phase column with a mobile phase composed of acetic acid and isopropanol (70:30, v/v). A fluorescence detector was used for quantification. The detection limit was 4 ng/g fat. The mean recoveries of added amounts of skatole and indole were 98.9 and 93.8%, respectively. The mean coefficients of variation were: inter-assay, 6.6% (skatole) and 8.8% (indole); intra-assay, 4.2% (skatole) and 2.9% (indole). Mean skatole concentrations in fat samples from boars (40 ng/g; n = 349) were not significantly higher than those from barrows (24 ng/g; n = 98).

Adipose Tissue↗
PubMed1992

Perinatal hip assessment in very low birth weight infants.

Fifty healthy low birth weight infants (less than 1500 g) without risk factors for congenital hip dysplasia (CHD) were examined by ultrasonography (100 hips) at 40 weeks corrected age and controlled at 3 months postnatal age. Sonographic assessment was performed using the classification of Graf. A physiological delay of hip maturation was observed in 10% of the patients (type IIa). At follow-up all of them had normal hip morphology without any pathological finding. Our results suggest that prematurity alone should not be considered a risk factor for CHD.

Female↗
PubMed1992

Estrogens and prostaglandin F2alpha in the semen and blood plasma of stallions.

A study was performed to determine the levels of estrogens and prostaglandin F2alpha in the stallion ejaculate. Simultaneous semen and blood plasma samples were collected from 19 stallions, 2 weeks apart, during the breeding season. Although not statistically different, the total mean estrogen content tended to be higher in seminal plasma (4447 pg/ml) than in blood (2497 pg/ml). A tendency was found for higher mean estrone sulphate concentrations than for total free steroid in both seminal (4116.1 vs 330.5 pg/ml) and blood plasma (2447.1 vs 49.5 pm/ml). Mean concentrations of estrone in ejaculate and blood plasma were 257.1+/-267.0 (SD) and 9.5+/-5.4 pg/ml, respectively. Estradiol-17beta concentrations were 73.4+/-87.4 and 40.0+/-27.6 pg/ml in ejaculates and blood plasma, respectively. Mean PGF2alpha concentrations tended to be much higher than total estrogens (1106.8+/-1636.4, SD, vs approximately 260 ng/ejaculate, respectively). To our knowledge this is the first report of PGF2alpha and estrogen concentrations in the stallion ejaculate.

Journal Article↗
PubMed1991

Rapid and accurate high-performance liquid chromatographic method for the determination of 3-methylindole (skatole) in faeces of various species.

A rapid method for the determination of skatole (3-methylindole) in faeces by reversed-phase high-performance liquid chromatography is described. Samples of 0.5 g were extracted with 2 ml of methanol. The extract was purified on Amberlite XAD-8. The lower limit of detection was 2.5 ng per injection (0.2 microgram/g faeces). The mean recovery of skatole was 95%, and the mean coefficients of variation were 7.0% (intra-assay) and 11.8% (inter-assay). Skatole concentrations were clearly lower in faeces from ruminants (average 2.6 micrograms/g for goat, sheep and cattle) than in those from monogastrics. Mean concentrations in human samples were 15.5 micrograms/g, and 10 micrograms/g in mature domestic pigs. An effect of the anabolic status on skatole concentrations in faeces of pigs is likely.

Animals↗
PubMed1991

Variation in estrus-related odors in the cow and its dependency on the ovary.

Urine samples were collected from 10 cows during the estrous cycle (Day 0=day of observed estrus) and investigated for pheromone activity using a quantitative rat bioassay. Pheromone activity in this assay was given in impulses/45 sec. Progesterone was measured in milk fat to verify the stage of cycle. The maximal response of rats was found on Day -1 (20.0 +/- 3.5 impulses/45 sec; x +/- SEM), and impulse rates were clearly higher (P <or= 0.001) than in the diestrous urine samples (5.2 +/- 0.7 impulses/45 sec) from Day -2 to Day +2. A negative correlation (r = -0.34; P <or= 0.001) was found between progesterone concentrations and impulse rates. The dependence of pheromone activity on estradiol was investigated in urine samples from six ovariectomized cows collected before and after estradiol administration. In all cows estradiol led to clear estrous symptoms, but it did not induce pheromone activity in urine. It is concluded that the appearance of maximal pheromone activity one day before estrus signals the imminence of estrus to the bull. The presence of the ovary seems to be essential for the synthesis of the pheromone, and an estrogen-dependent source outside the ovary is unlikely.

Journal Article↗
PubMed1991

Rapid biometric assessment of gestational age in very low birth weight infants.

Foot length and intermamillary distance were compared to gestational age assessment using obstetrical dates, physical criteria of Ballard score and the evaluation of the anterior vascular capsule of the lens (IPM). Thirty-eight healthy and appropriate for gestational age preterm infants (30 +/- 2.4 weeks) with a birth weight of 1280 +/- 410 g were studied. Internipple distance (IM) and foot length (FL) were measured with a sliding caliper graduated in millimeters. Results were analyzed using the linear regression analysis. Obstetrical dates, physical Ballard score and IMP correlated significantly with both biometric measurements. Mean IM was 58.5 +/- 8.5 mm (range: 45 mm-89 mm) and mean FL was 60.6 +/- 7.9 mm (range: 45 mm-75 mm). The data indicate that the appropriate use of biometric parameters in the early postnatal period can be used to improve assessment of gestational age in VLBW infants.

Biometry↗
PubMed1990

Procedure for the purification of streptavidin by hydrophobic interaction chromatography.

A procedure is described for the purification of hydrophobic microbial proteins such as streptavidin from Streptomyces avidinii, using Benzyl-DC bead cellulose as the column material. The separation is rapid with a high loading capacity and sufficient resolution for preparative uses. Advantages are discussed especially for industrial purposes.

Bacterial Proteins↗
PubMed1990

Effect of pheromones from male goats on LH-secretion in anoestrous ewes.

Pheromones from ram's wool or buckhairs lead to an increase in the LH pulse frequency, thus inducing ovulations in seasonally anoestrous sheep and goats, respectively. Indications exist that pheromones from one species may be active in the other one. The changes of the LH secretion pattern were used as a bioassay to demonstrate such an interspecies effect of either ram's wool or buckhairs. A clear increase in the LH pulse frequency was obvious in ewes after stimulation with buckhairs (p less than or equal to 0.001, n = 11), but was absent in does after application of ram's wool or its extracts. Organic solvent extracts from buckhairs were split into a neutral (FN) and an acid fraction (FA). The latter one was further divided into two subfractions (FA-I, FA-II) according to the chain length of the fatty acids. The most pronounced effect was found after FN (p less than or equal to 0.001, n = 12), but FA still remained significantly active (p less than or equal to 0.05, n = 9). The subfractions FA-I and FA-II, however, had largely lost the pheromonal activity. It is concluded that buck pheromones are active in sheep. The neutral fraction is likely to contain the bulk of pheromonally active substances.

Animals↗
PubMed1990

Are soluble monocyte-derived HLA class II molecules candidates for immunosuppressive activity?

Supernatants of human blood monocyte cultures suppressed PHA responses (IL-2 synthesis, IL-2R expression, DNA synthesis) of autologous and allogeneic lymphocytes. The main suppressive activity was found in the 65-kDa (and 23-kDa) range. It could be incompletely neutralized by mAb specific for a non-polymorphic HLA DR determinant and could also be adsorbed to and eluted from an anti-DR immunoabsorbent column. On blots of monocyte lysates and monocyte culture supernatants, the mAb RoDR recognized antigens of nearly the same Mr. The hypothesis that soluble HLA DR alpha beta heterodimers or beta chains are likely candidates for the suppressor factor was confirmed by analogous effects of purified HLA DR molecules. We favor a model in which soluble MHC class II molecules (in contrast to surface-bound ones) may interfere with the association and cross-linking processes necessary for T cell activation by competing for CD4 binding sites.

Antibodies, Monoclonal↗
PubMed1990

Influence of mating and intra-uterine oestradiol infusion on peripheral oxytocin concentrations in the sow.

Oxytocin concentrations were measured radioimmunologically in sows on the day of standing oestrus over a 6-h period (controls, n = 6) or 1 h before and 5 h after mating (n = 5) or transcervical infusion of either 100 ml saline (0.9% (w/v) NaCl, n = 7) or saline plus 10 micrograms oestradiol (simulation of seminal oestrogens, n = 5). In the controls, oxytocin was low, at around 1.0 pmol/l, throughout the investigation period. Similarly, saline infusion did not lead to a noticeable change in oxytocin concentrations in six out of seven sows. In one sow, however, infusion led to a maximum of 86 pmol/l at 1 min after infusion. Oestradiol led to no immediate increase in oxytocin concentrations. Later in the post-treatment period (2-5 h) they were only slightly increased (1 pmol/l vs 3 pmol/l). All mated sows reacted with a rapid and clear increase in oxytocin. Maximal concentrations (42.0 +/- 5.1 pmol/l; mean +/- S.E.M.) appeared 2 min after the onset of ejaculation. Clearly increased concentrations were found for 40 min. It was concluded that mating specifically leads to a rise in oxytocin, probably due to both mechanical and pheromonal stimuli provided by the boar.

Animals↗
PubMed1990

Physiological role of seminal components in the reproductive tract of the female pig.

In many species the appearance of oestrus is sufficient to ensure that the time of ejaculation, sperm transport and capacitation are balanced with the time of ovulation. In the pig these phenomena vary considerably and require additional regulatory mechanisms which are partly explained by seminal components. Boar semen is rich in oestrogens (up to 11.5 micrograms/ejaculate). Infusion of saline with the addition of oestrogens in physiological amounts increased the myometrial contraction frequency up to 2.5-fold. This effect is explained by a release of PGF-2 alpha immediately after oestrogen infusion. Such an infusion also raises peripheral oestrogen concentrations and an effect on LH release can be demonstrated. Additionally, PGF-2 alpha is measurable in uterine vein plasma after oestrogen infusion and is transferred into the follicular fluid. The effect of oestrogens on LH and follicular PGF-2 alpha is likely to contribute to the timing of ovulation in response to mating. A specific protein of Mr 100,000-110,000 has been detected in boar seminal plasma and it exerts a strong immunosuppressive effect. This protein may be involved in a protection of spermatozoa but also of early embryos against female immunological attack. The addition of such specific compounds to AI doses, in which seminal plasma is diluted, may improve prolificacy.

Animals↗