Search PubMed⌕ Search

Biomedical subjects

R Stoll

Publications and source records attributed to R Stoll.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Intravenous immunoglobulin substitution in patients with ARC and AIDS (WR 3-6)].

HIV-infected patients acquire a profound dysfunction in humoral and cellular immunity. This immunological impairment causes a markedly increased incidence of recurrent infections. While effective prophylaxis of Pneumocystis carinii pneumonia is available, infections with other microorganisms still cause a high rate of morbidity and mortality. Preliminary results of our randomized outpatient trial to evaluate the efficacy of intravenous immunoglobulin (IVIG) in adults demonstrate that IVIG reduces the episodes of fever, diarrhea, and the duration of hospitalization. We also found a significant reduction of mortality due to infection.

AIDS-Related Complex↗
PubMed1994

[Mercury concentrations in the urine of children with and without amalgam fillings].

Studies on adults documented that most of the urinary concentration in occupationally non-exposed persons is determined by the number and extent of their amalgam fillings. Very few data concerning the mercury exposure of children are available. In this study the mercury concentration in the urine of 3-15-year-old children with and without amalgam fillings was determined. The mean urinary mercury concentration for the children without amalgam (n = 93) was 0.17 microgram/l, and for the children with amalgam fillings (n = 86) it was 0.70 microgram/l. The creatinine adjusted values were 0.19 microgram/g and 0.64 microgram/g, respectively. This difference was significant (p < 0.001). Also, a significant correlation was found between the number of amalgam points (each amalgam surface had been given 1 to 3 points depending on its extent) and the urinary mercury concentration (r = 0.69).

Adolescent↗
PubMed1993

Action of estradiol and tamoxifen on the Müllero-regressive activity of the chick embryonic testis assayed in vivo by organotypic grafting.

In the chick, the implantation of a testis graft from a 13-day-old male donor embryo into the extra-embryonic coelom of 3-day-old female embryos induces the total regression of their Müllerian ducts because of the anti-Müllerian hormone (AMH or MIS) secreted by the implant. Pre-treatment of the donors with estradiol (E2), between day 12 and day 13, counteracts in a significant way the Müllero-regressive activity of the implant. Co-treatment of donors at the same stage with both Tamoxifen (TAM) and E2 restores the initially observed activity, thus demonstrating the presence of Tamoxifen-sensitive estrogen receptors at the late stage of treatment in the Sertoli cells responsible for AMH secretion. The treatment of 3-day-old male donor embryos with E2 causes the differentiation of their left gonad into an ovotestis which provides implants totally devoid of Müllero-regressive activity. The additional treatment with TAM of the grafted host embryos, does not modify the results obtained when E2-treated male gonads are grafted to host embryos not treated with TAM. This shows that the lack of Müllero-regressive activity exhibited by the E2-treated male gonads does not depend on the estrogens they may secrete during the time of the assay, i.e., it cannot be attributed to a protecting action of estrogens on the MDs of the host. Our results therefore favor the idea that E2 down-regulates AMH. The relevance of such a regulation to the phenomenon of Müllerian duct maintenance, either in the E2-feminized male or in the female chick embryo, is discussed.

Animals↗
PubMed1993

Action of estradiol and tamoxifen on the testis-inducing activity of the chick embryonic testis grafted to the female embryo.

The implantation of two testes from 13-day-old male chick donor embryos into the extra-embryonic celom of 3-day-old female embryos induces the masculinization of their ovaries up to a total and definitive inversion of their gonadal sex, i.e., the differentiation of testes in the female hosts. Pretreatment of the donors with estradiol (E2) between day 11 and 13 counteracts the testis-inducing activity of the implants, while co-treatment of donors with both tamoxifen (TAM) and E2 at the same stage restores the initially observed activity. The treatment of 3-day-old male donor embryos with E2 causes the differentiation of their left gonad into an ovotestis totally devoid of testis-inducing activity once grafted in the same conditions as above. An additional treatment with TAM of the grafted host embryos does not modify the results obtained when E2-treated male gonads are grafted to normal host embryos. This shows that the lack of testis-inducing activity exhibited by the E2-treated grafts can not be attributed to a protecting action of endogenous estrogens on the gonads of the host. On account of previous work showing the inhibition by E2 of the Müllero-regressive activity of the chick embryonic testis, our present results can be interpreted in terms of E2-down regulation of Anti-Müllerian Hormone (AMH or MIS), which appears to be a good candidate as testis-inducer. The relevance of our results to the phenomenon of gonad differentiation is discussed.

Animals↗
PubMed1993

Molecular and biological characteristics of avian polyomaviruses: isolates from different species of birds indicate that avian polyomaviruses form a distinct subgenus within the polyomavirus genus.

The isolation and characterization of two avian polyomaviruses, from chicken (BFDV-2) and a parrot (BFDV-3), is reported. Both isolates are closely related to the non-mammalian polyomavirus budgerigar fledgling disease virus (BFDV) isolated from budgerigars (now called BFDV-1), and all three viral genomes are shown to have the same basic size of 4981 bp. A 151 bp insertion was, however, observed in the non-coding region of BFDV-2 which represented an exact duplication of the left half of the non-coding region, including the putative early promoter and amino terminus of the large T antigen. With a further 15 base pairs exchanged elsewhere throughout the three genomes, these viruses have distinct degrees of tropism for various avian species. The production of antibodies directed against a beta-galactosidase-large T antigen fusion protein of BFDV-1 is described. These antibodies detected the large T antigen, with an M(r) of approximately 80K, and the small t antigen, with an M(r) of approximately 24K, in cells infected with BFDV isolates. Whereas these antibodies bind with low affinity to the large T antigen of simian virus 40 (SV40), SV40- or mouse polyomavirus-specific antibodies will not bind to the BFDV large T antigen. Antibodies directed against BFDV structural polypeptides exhibit broad, reciprocal cross-reactivities with all three structural proteins of mammalian polyomaviruses. The significance of polyomavirus infections in various avian species is discussed. Based on unique structural and biological properties we propose that these viruses should be placed in a distinct subgenus (Avipolyomavirus) within the polyomaviruses.

Animals↗
PubMed1993

Cholecystokinin in the control of gastric acid secretion in man.

This study was designed to determine the role of cholecystokinin in the control gastric acid secretion in men using loxiglumide, a specific cholecystokinin receptor blocker. Three groups of healthy subjects (A, B, and C) were used; group A--for studies with postprandial gastric secretion, group B--for studies with exogenous gastric secretagogues and group C--for 12 hour intragastric pH-metry. Cephalic phase stimulated by modified sham feeding in group A subjects increased gastric acid secretion to about 50% of pentagastrin maximum and the treatment with loxiglumide in a standard dose (20 mumol/kg iv loading dose plus infusion of 20 mumol/kg/h afterwards) failed to affect this secretion. Gastric acid response to a 5% peptone meal instilled intragastrically greatly enhanced gastric acid secretion and plasma gastrin concentration but the addition of loxiglumide in the standard dose resulted in further increase in both gastric acid and plasma gastrin responses to peptone meal. Infusion of caerulein in gradually increasing doses (15-120 pmol/kg/h) and gastrin releasing peptide (25-200 pmol/kg/h) resulted in a dose dependent stimulation of gastric acid secretion reaching about 35% and 25% of maximum attained with pentagastrin. When loxiglumide was added in a standard dose, the acid responses to caerulein and gastrin releasing peptide were further increased two to three fold attaining the peak reaching, respectively, about 100% and 50% of pentagastrin maximum. In group C subjects, 12 hour pH-metry revealed the usual increase in gastric pH after each meal in tests with placebo. Loxiglumide (1200 mg tablets tid, po) resulted in significantly lower pH after each meal and this was accompanied by significantly higher gastrin responses than in placebo tests. We conclude that cholecystokinin released by peptone meal, ordinary meals or gastrin releasing peptide exerts a potent inhibitory influence on gastric acid secretion and gastrin release in men and this inhibition involves subtype A cholecystokinin receptors.

Adult↗
PubMed1993

Cholecystokinin in the regulation of gastric acid and endocrine pancreatic secretion in humans.

In this study, a selective antagonist of cholecystokinin (CCK)-A receptors, loxiglumide, was used to evaluate the role of CCK in the control of the release of gastrin and pancreatic hormones (insulin, glucagon, pancreatic polypeptide (PP), and somatostatin) after stimulation with exogenous CCK and ingestion of a standard liquid mixed meal in healthy humans. Exogenous CCK-8, which induced a small but significant increase in gastric acid secretion, resulted in dose-dependent increments in plasma PP levels without significant changes in plasma levels of insulin, glucagon, or somatostatin. Pretreatment with loxiglumide resulted in a marked increase in CCK-induced gastric acid secretion and abolished the increments in plasma PP without alteration of plasma insulin, glucagon, or somatostatin levels. Ingestion of the liquid meal resulted in an immediate rise in intragastric pH from basal values of about 2 to pH6 lasting 90-120 min, and this was accompanied by significant increments in plasma gastrin, insulin, glucagon, PP, and somatostatin. Administration of loxiglumide (1200 mg orally) caused a reduction in the postprandial intragastric pH and the two- to three-fold increase in plasma gastrin. Plasma insulin and glucagon levels in tests with loxiglumide tended to increase, probably owing to accelerated gastric emptying, whereas plasma PP and somatostatin were significantly reduced. This study provides evidence that CCK exerts an inhibitory effect on gastric acid secretion and plasma gastrin release as well as a stimulatory influence on the release of PP and somatostatin via CCK-A receptors but does not influence directly insulin or glucagon secretion in man.

Adult↗
PubMed1993

Gastric mucosal blood flow and neutrophil activation in aspirin-induced gastric mucosal damage in man.

Gastric and intestinal injury induced by nonsteroidal anti-inflammatory agents (NSAIDs) such as aspirin (ASA) is a common side effect of this class of drugs, but the mechanism by which these drugs act is not fully explained. In this study the effects of 3 days of continuous oral ASA administration (1 g twice daily) to eight healthy male volunteers were studied. To estimate the extent of mucosal damage, gastroscopy was performed before and after 3 days of ASA treatment, during which the mucosal blood flow was measured by means of laser-Doppler flowmetry. Before each endoscopy gastric microbleeding was measured. Since neutrophil activation has recently been suggested to be involved in the pathogenesis of ASA-induced gastric mucosal damage, we examined the influence of ASA treatment on the activation of leukocytes by determining their association with platelets in the blood. Aspirin-induced acute gastric damage reached about 3.5 in the endoscopic Lanza score. Mucosal blood flow increased significantly after ASA treatment, by about 50% in the oxyntic gland area and by 87% in the antral area. Gastric microbleeding rose from about 0.38 ml/day in the intact stomach to about 7.7 ml/day after ASA treatment. The platelet/neutrophil adherence increased significantly in both thrombin-unstimulated and thrombin-stimulated platelets. We conclude that acute 3 days' administration of ASA in man produces well-defined areas of gastric damage accompanied by a significant increase in gastric microbleeding and gastric blood flow and that ASA promotes platelet/neutrophil adhesion that may resemble the neutrophil/endothelium interaction in the gastric mucosa.

Adult↗
PubMed1991

In vivo characterization of the Saccharomyces cerevisiae centromere DNA element I, a binding site for the helix-loop-helix protein CPF1.

The centromere DNA element I (CDEI) is an important component of Saccharomyces cerevisiae centromere DNA and carries the palindromic sequence CACRTG (R = purine) as a characteristic feature. In vivo, CDEI is bound by the helix-loop-helix protein CPF1. This article describes the in vivo analysis of all single-base-pair substitutions in CDEI in the centromere of an artificial chromosome and demonstrates the importance of the palindromic sequence for faithful chromosome segregation, supporting the notion that CPF1 binds as a dimer to this binding site. Mutational analysis of two conserved base pairs on the left and two nonconserved base pairs on the right of the CDEI palindrome revealed that these are also relevant for mitotic CEN function. Symmetrical mutations in either half-site of the palindrome affect centromere activity to a different extent, indicating nonidentical sequence requirements for binding by the CPF1 homodimer. Analysis of double point mutations in CDEI and in CDEIII, an additional centromere element, indicate synergistic effects between the DNA-protein complexes at these sites.

Base Sequence↗
PubMed1991

[Contribution of experimental intersexuality in chickens to the problem of gonadal differentiation and its abnormalities in amniotic vertebrates].

The grafting of embryonic testes to chick embryos realizes an experimental model which is near the spontaneous situation of the cattle "free-martin". It allows to obtain a masculinization of female host embryos developing in some cases up to a total and definitive reversal of sex differentiation. Indeed, it is possible, by this way to obtain testes induced under the influence of substance(s) secreted by the grafts which determine epigenetically a sexual phenotype opposite to the genotype of the host embryos. The analysis of such testis morphogenesis shows that it results from an inhibitory mechanism. Some experimental data strongly suggest to ascribe it to the anti-Mullerian hormone secreted by the graft. The ovotestes and testes observed in adult treated animals present various degrees of development, especially at the level of seminiferous tubules in which the spermatogenesis, when present, may be completed until spermatozoa. Some gonadal abnormalities interesting genetically female human beings, like a majority of the hermaphrodites, or certain XX men, are discussed at the light of these experimental data.

Animals↗
PubMed1991

[The dimensional stability of hydrophilic impression materials after application of a disinfectant].

The influence of a disinfectant solution containing glutaraldehyde on the dimensional stability of 2 alginate and 4 elastomeric impression materials has been investigated. Die models were measured using a computer-controlled method and compared to the master die to assess the three-dimensional change in the impression material. After an immersion time of 10 min, a dimensional change did not occur. When using immersion times longer than 10 min, the accuracy of the alginate materials was generally more affected by the disinfecting solution than that of the elastomeric impression materials.

Alginates↗
PubMed1991

[Compared action of norethindrone and various steroids on Müller ducts of the female chick embryo].

Treatment of female chick embryo with norethindrone (NET), a potent progesterone-like steroid, caused caudal agenesia and cephalic regression of Mullerian ducts as the normal regression induced by anti-Mullerian-hormone in the male embryo. The comparative study of five other progesterone-like steroids shows that only lynestrenol which is metabolized into NET at least in man, possesses the same properties as NET. The four others, i.e. medroxyprogesterone, medrogestone, norgestrienone and 17 alpha hydroxyprogesterone are only able to induce agenesia, an unspecific property, which was observed with many steroidal hormones, as norethandrolone here studied.

Animals↗
PubMed1990

Action of estradiol on müllerian duct regression induced by treatment with norethindrone of female chick embryos.

Treatment of genetically female chick embryos with norethindrone (NET), a progesterone-like steroid chemically related to testosterone, caused two types of Müllerian duct (MD) deficiencies. The first consisted in an absence of the caudal part of the ducts owing to their partial agenesia occurring between Days 5 and 7 of embryonic life. This is nonspecific since it was observed after a treatment with almost all steroidal sex hormones. In particular, this was obtained with estradiol which also increases the frequency and extent of agenesia caused by the NET, as reported here. The second type of deficiency appeared between Days 12 and 14 and was due to a regression destroying the more or less large part of the MDs having escaped agenesia, i.e., for most of the cephalic half. This resulted from the influence of the anti-Müllerian hormone originating from the ovary and normally inhibited by the ovarian estrogens. This protective action of endogenous estrogens was inhibited by the NET, but an additional treatment with estradiol removed this inhibition and prevented duct regression. Our results suggest that estrogen protects the duct from the regression induced indirectly by NET, by acting both at gonad and MD levels.

Animals↗
PubMed1990

[Computer-assisted technologies in dentistry].

The introduction and production of the Cerec-System was the first time, when a method of computer-aided design and manufacturing (CAD/CAM) of dental restorations moves to the chairside. New technologies like optical impression, solid modelling of crown shapes by CAD-Programs or computer controlled milling were acquired from the field of industrial production. Nevertheless, the Cerec-Systems is indicated only in a limited range of clinical situations, and the production of a well fitting computer-designed full crown is not yet possible at this stage of development. It can only be guessed whether these advancements will be achieved in the near future.

Crowns↗