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Biomedical subjects

I Schneider

Publications and source records attributed to I Schneider.

At least 37 records · Page 2Linked to original sources
PubMed2001

Mutant presenilins disturb neuronal calcium homeostasis in the brain of transgenic mice, decreasing the threshold for excitotoxicity and facilitating long-term potentiation.

Mutant human presenilin-1 (PS1) causes an Alzheimer's-related phenotype in the brain of transgenic mice in combination with mutant human amyloid precursor protein by means of increased production of amyloid peptides (Dewachter, I., Van Dorpe, J., Smeijers, L., Gilis, M., Kuiperi, C., Laenen, I., Caluwaerts, N., Moechars, D., Checler, F., Vanderstichele, H. & Van Leuven, F. (2000) J. Neurosci. 20, 6452-6458) that aggravate plaques and cerebrovascular amyloid (Van Dorpe, J., Smeijers, L., Dewachter, I., Nuyens, D., Spittaels, K., van den Haute, C., Mercken, M., Moechars, D., Laenen, I., Kuipéri, C., Bruynseels, K., Tesseur, I., Loos, R., Vanderstichele, H., Checler, F., Sciot, R. & Van Leuven, F. (2000) J. Am. Pathol. 157, 1283-1298). This gain of function of mutant PS1 is approached here in three paradigms that relate to glutamate neurotransmission. Mutant but not wild-type human PS1 (i) lowered the excitotoxic threshold for kainic acid in vivo, (ii) facilitated hippocampal long-term potentiation in brain slices, and (iii) increased glutamate-induced intracellular calcium levels in isolated neurons. Prominent higher calcium responses were triggered by thapsigargin and bradykinin, indicating that mutant PS modulates the dynamic release and storage of calcium ions in the endoplasmatic reticulum. In reaction to glutamate, overfilled Ca(2+) stores resulted in higher than normal cytosolic Ca(2+) levels, explaining the facilitated long-term potentiation and enhanced excitotoxicity. The lowered excitotoxic threshold for kainic acid was also observed in mice transgenic for mutant human PS2[N141I] and was prevented by dantrolene, an inhibitor of Ca(2+) release from the endoplasmic reticulum.

Animals↗
PubMed2001

[Bilateral, asymmetric herpes zoster (herpes zoster duplex asymmetricus)].

A 73-year-old female patient presented with asymmetric herpes zoster. She was treated successfully with systemic immunostimulants, vitamin B1 tablets and topical etheric acetyl-salicylic acid solution. No underlying malignancy, immunodeficiency or other systemic diseases could be detected.

Administration, Oral↗
PubMed2001

Is interleukin-6 concentration in the dialysate of continuous ambulatory peritoneal dialysis patients a prognostic parameter in peritonitis?

In continuous ambulatory peritoneal dialysis (CAPD) patients, peritonitis is a dangerous complication. Chemical examinations in the dialysate can be successfully used to assess permeability disturbances, hemostatic balance, and (for early detection and follow-up) cellular inflammatory reaction. In 7 CAPD patients (age: 50 +/- 15 years; dialysis duration: 40 +/- 24 months) with peritonitis episodes, and in 17 age-matched CAPD patients (age: 50 +/- 13 years; dialysis duration: 29 +/- 18 months) without peritonitis, we examined daily dialysate cell count (CC) and concentrations of albumin (ALB), immunoglobulin G (IgG), thrombin-antithrombin III complex (TAT), D-dimer (DD), and interleukin-6 (IL-6) after the long dwell (8-10 hours) over an interval of at least 14 days. In CAPD patients with peritonitis episodes, all parameters (CC, ALB, IgG, TAT, DD, IL-6) were significantly increased in the first days [IL-6 mean: 25,190 pg/mL (range: 2560-52,708 pg/mL) vs 66 pg/mL (range: 21-163 pg/mL)]; then, up to day 14 after successful therapy with antibiotics, the levels showed no differences as compared with CAPD patients without peritonitis. In the case of relapse of peritonitis (4 cases), concentration of IL-6 rose again on day 14, 1 day earlier than did the other parameters. Determination of IL-6 in the dialysate is a reliable prognostic parameter for the course of peritonitis (start, end, relapse) in CAPD patients.

Adult↗
PubMed2000

[Immunomodulation with fumaric acid. Systemic therapy in psoriasis].

The treatment of psoriasis vulgaris with fumaric acid esters has been controversial for more than 30 years. Recently the fumaric acid derivatives are marketed antipsoriatics in many European countries. In this paper the clinical efficacy, the side effects as well as the mode of action of these highly potent substances are summarized.

Dermatologic Agents↗
PubMed2000

Altered intracellular calcium homeostasis in cerebellar granule cells of prion protein-deficient mice.

Previous studies have indicated that recombinant cellular prion protein (PrP(C)), as well as a synthetic peptide of PrP(C), affects intracellular calcium homeostasis. To analyze whether calcium homeostasis in neurons is also affected by a loss of PrP(C), we performed microfluorometric calcium measurements on cultured cerebellar granule cells derived from prion protein-deficient (Prnp(0/0)) mice. The resting concentration of intracellular free calcium [Ca(2+)](i) was found to be slightly, but significantly, reduced in Prnp(0/0) mouse granule cell neurites. Moreover, we observed a highly significant reduction in the [Ca(2+)](i) increase after high potassium depolarization. Pharmacological studies further revealed that the L-type specific blocker nifedipine, which reduces the depolarization-induced [Ca(2+)](i) increase by 66% in wild-type granule cell somas, has no effect on [Ca(2+)](i) in Prnp(0/0) mouse granule cells. Patch-clamp measurements, however, did not reveal a reduced calcium influx through voltage-gated calcium channels in Prnp(0/0) mice. These data clearly indicate that loss of PrP(C) alters the intracellular calcium homeostasis of cultured cerebellar granule cells. There is no evidence, though, that this change is due to a direct alteration of voltage-gated calcium channels.

Animals↗
PubMed2000

Anthranoid laxative use is not a risk factor for colorectal neoplasia: results of a prospective case control study.

BACKGROUND: Anthranoid laxatives are the most commonly used purgatives in the therapy of acute and chronic constipation. Recent experimental data and a prospective cohort study provide evidence of a possible risk of anthranoid use for the development of colorectal neoplasms. MATERIALS AND METHODS: We performed a prospective case control study at the University of Erlangen to investigate the risk of anthranoid laxative use for the development of colorectal adenomas or carcinomas. A total of 202 patients with newly diagnosed colorectal carcinomas, 114 patients with adenomatous polyps, and 238 patients (controls) with no colorectal neoplasms who had been referred for total colonoscopy were studied. The use of anthranoid preparations was assessed by standardised interview, and endoscopically visible or microscopic melanosis coli was studied by histopathological examination. RESULTS: There was no statistically significant risk of anthranoid use for the development of colorectal adenomas (unadjusted odds ratio 1.0; 95% CI 0.5-1.9) or carcinomas (unadjusted odds ratio 1.0; 95% CI 0.6-1.8). Even after adjustment for the risk factors age, sex, and blood in the stools by logistic regression analysis the odds ratio for adenomas was 0.84 (95% CI 0. 4-1.7) and for carcinomas 0.93 (95% CI 0.5-1.7). Also, there were no differences between the patient and control groups for duration of intake. Macroscopic and high grade microscopic melanosis coli were not significant risk factors for the development of adenomas or carcinomas. CONCLUSION: Neither anthranoid laxative use, even in the long term, nor macroscopic or marked microscopic melanosis coli were associated with any significant risk for the development of colorectal adenoma or carcinoma.

Adenoma↗
PubMed1999

Laparoscopic-assisted colon anastomosis using the Valtrac ring: an animal study.

PURPOSE: For deep colon anastomoses in laparoscopic surgery, the mainstay is the circular stapler. Theoretically, however, such anastomoses can also be constructed with the aid of the Valtrac ring. The aim of the present study was to investigate the feasibility of this approach. METHODS: In this approved animal study nine pigs weighing 15 to 20 kg were operated on under general anesthesia. After intracorporeal preparation, the colon was divided at the level of the entry to the pelvis. To fix the proximal half of the Valtrac ring, the proximal limb of the colon was exteriorized via a minilaparotomy. After replacing this part of the colon--now bearing the Valtrac ring--in the abdominal cavity and reestablishment of pneumoperitoneum, the ring was fixed to the applicator inserted transanally into the abdominal cavity. After placement of the distal half of the ring in the rectal limb and extracorporeal knotting of the pursestring suture previously placed with the aid of the laparoscopic pursestring clamp, the two halves of the Valtrac ring were reliably closed with the help of the applicator. RESULTS: Eight of nine animals survived. One animal died on the fourth postoperative day as a result of an anastomotic insufficiency. At follow-up examination in the fifth postoperative week, none of the surviving eight animals showed any signs of prior anastomotic insufficiency. CONCLUSION: This animal study has shown that using the newly developed applicator system, the Valtrac ring can be just as readily employed as the circular stapler for creation of a colonic anastomosis below the level of the promontorium.

Anastomosis, Surgical↗
PubMed1999

Alpha 1-adrenergic receptor-mediated increase in the mass of phosphatidic acid and 1,2-diacylglycerol in ischemic rat heart.

OBJECTIVE: 1,2-Diacylglycerol (1,2-DAG) and phosphatidic acid (PA) are produced by phospholipase C and D activity and play a key role as second messengers in receptor-mediated signal transduction. So far, little is known about alterations of endogenous 1,2-DAG and PA production during myocardial ischemia. METHODS: Rat isolated perfused hearts were subjected to global ischemia, total lipids were extracted, and separated by thin-layer chromatography. The mass of PA and 1,2-DAG were quantified using laserdensitometric analysis of visualized lipids. RESULTS: Compared to normoxic control values (1,2-DAG 713 +/- 45 ng/mg protein, PA 171 +/- 11 ng/mg protein), the myocardial content of 1,2-DAG and PA was unaltered after 10 min of ischemia. Prolonged myocardial ischemia (20 min), however, which was accompanied by marked overflow of endogenous norepinephrine, significantly increased the mass of both second messengers (1,2-DAG 1062 +/- 100 ng/mg protein, PA 340 +/- 29 ng/mg protein). The increase in PA and 1,2-DAG in response to ischemia was abolished by inhibition of ischemia-induced norepinephrine release as well as by alpha1-adrenergic blockade but unaffected by beta-adrenergic blockade. While inhibition of diacylglycerol kinase did not affect ischemia-induced increase in PA and 1,2-DAG, inhibition of phosphatidylinositol-specific phospholipase C activity significantly suppressed ischemia-induced increase in 1,2-DAG but did not affect endogenous production of PA indicating phospholipase C-independent formation of PA and activation of both, phospholipase C and D, in the ischemic heart. CONCLUSIONS: Ischemia elicits an alpha1-adrenergic receptor-mediated increase in the mass of myocardial PA and 1,2-DAG. The increase in endogenous PA is suggested to be due to the activation of myocardial phospholipase D, whereas 1,2-DAG is formed predominantly by activation of phospholipase C in the ischemic heart.

Adrenergic Uptake Inhibitors↗
PubMed1999

A novel type of AmpC beta-lactamase, ACC-1, produced by a Klebsiella pneumoniae strain causing nosocomial pneumonia.

A Klebsiella pneumoniae strain resistant to oxyimino cephalosporins was cultured from respiratory secretions of a patient suffering from nosocomial pneumonia in Kiel, Germany, in 1997. The isolate harbors a bla resistance gene located on a transmissible plasmid. An Escherichia coli transconjugant produces a beta-lactamase with an isoelectric point of 7.7 and a resistance phenotype characteristic of an AmpC (class 1) beta-lactamase except for low MICs of cephamycins. The bla gene was cloned and sequenced. It encodes a protein of 386 amino acids with the active site serine of the S-X-X-K motif at position 64, as is characteristic for class C beta-lactamases. Multiple alignment of the deduced amino acid sequence with 21 other AmpC beta-lactamases demonstrates only very distant homology, reaching at maximum 52.3% identity for the chromosomal AmpC beta-lactamase of Serratia marcescens SR50. The beta-lactamase of K. pneumoniae KUS represents a new type of AmpC-class enzyme, for which we propose the designation ACC-1 (Ambler class C-1).

Adult↗
PubMed1999

Discrimination of Burkholderia multivorans and Burkholderia vietnamiensis from Burkholderia cepacia genomovars I, III, and IV by PCR.

We present a PCR procedure for identification of Burkholderia cepacia, Burkholderia multivorans, and Burkholderia vietnamiensis. 16S and 23S ribosomal DNAs (rDNAs) of B. multivorans and B. vietnamiensis were sequenced and aligned with published sequences for definition of species-specific 18-mer oligonucleotide primers. Specific antisense 16S rDNA primers (for B. cepacia, 5'-AGC ACT CCC RCC TCT CAG-3'; for B. multivorans, 5'-AGC ACT CCC GAA TCT CTT-3') and 23S rDNA primers (for B. vietnamiensis, 5'-TCC TAC CAT GCG TGC AA-3') were paired with a general sense primer of 16S rDNAs (5'-AGR GTT YGA TYM TGG CTC AG-3') or with a sense primer of 23S rDNA (5'-CCT TTG GGT CAT CCT GGA-3'). PCR with these primers under optimized conditions is appropriate to specifically and rapidly identify B. multivorans, B. vietnamiensis, and B. cepacia (genomovars I, III, and IV are not discriminated). In comparison with the polyphasic taxonomic analyses presently necessary for species and genomovar identification within the B. cepacia complex, our procedure is more rapid and easier to perform and may contribute to clarifying the clinical significance of individual members of the complex in cystic fibrosis.

Burkholderia↗
PubMed1999

Rubidium marking of Anopheles stephensi (Diptera: Culicidae).

Immature Anopheles stephensi Liston were reared in untreated water and water containing eight 2-fold dilutions of rubidium (Rb) from 1,000 to 7.8 ppm to determine the concentration that allowed reliable detection and produced the least toxic effects as measured by adult emergence, weight, and survival. The amount of Rb detected in mosquitoes increased positively with increasing concentrations in the rearing water. Concentrations > or = 31.2 ppm Rb in the rearing water provided high and consistent detection levels of > or = 3,500 ppm Rb/mg of adult mosquito. There were no adverse effects of Rb on the weights of mosquitoes. However, increased Rb concentrations in the rearing water were associated with decreased emergence and survival. After 8 d, percentage emergence from Rb concentrations of 0-31.2 ppm was > or = 50%. At day 21, Rb concentrations of 0-31.2 ppm showed < or = 29% reduction of female survival compared with controls. The recommended concentration for reliable Rb detection with minimal toxic effects in An. stephensi was 32 ppm.

Animals↗
PubMed1999

Cutaneous signs of selected systemic diseases.

In this work we will discuss three cutaneous markers of systemic disease. Acanthosis nigricans is the most widely known in this category. Cutaneous angiokeratomas are usually associated with enzyme defect disorders, such as Fabry's disease, and are linked in this work as a reactive pattern in hepatorenal failure. Mast cell disease may occur in a number of forms, often with systemic involvement.

Acanthosis Nigricans↗
PubMed1998

[Imipenem resistance in Pseudomonas aeruginosa].

In 1997 in western Austria, 9.9% of Pseudomonas aeruginosa strains from patients of general practitioners were resistant to imipenem as well as 18.2% of the isolates from hospitals and 20.2% of the strains at a university teaching hospital. Within the hospital the imipenem resistance varied from 9.9% among out-patients to 28.7% in isolates from intensive care units. In medical/surgical words, up to 15.1% of P. aeruginosa strains were resistant to imipenem. The incidence of imipenem-resistant P. aeruginosa strains correlates to the use of carbapenems. In June 1997, 10 consecutive isolates from 8 patients were obtained and typed using restriction fragment length polymorphism analysis (RFLP) and Pyocin typing. All 10 isolates were resistant to meropenem as well as to imipenem. The finding (by RFLP and Pyocin typing) of individual bacterial types in each isolate strongly contradicts the spread of infection by cross infection. However, all patients were proven to have been treated with imipenem during the 3 months prior to testing. In 1997, 13,880 g of imipenem were used at the university hospital in Innsbruck. The use of carbapenems appears to be the main cause for the increased incidence of imipenem-resistant P. aeruginosa strains.

Austria↗
PubMed1998

[Angiolymphoid hyperplasia with eosinophilia].

The authors describe the case of a 38-year-old female patient suffering from angiolymphoid hyperplasia with eosinophilia. The symptoms, histopathology, differential diagnostic relations and the therapeutic modalities of this disease are discussed.

Adult↗