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Biomedical subjects

A Siebert

Publications and source records attributed to A Siebert.

18 recordsLinked to original sources
PubMed1998

Clostridium difficile-associated diarrhea in acute and long-term care facilities.

This report presents an overview of the epidemiology, diagnosis, complications, and treatment of Clostridium difficile-associated diarrhea in acute and long-term care facilities. More studies are needed to understand the epidemiology of this disease in long-term care facilities, to identify the risk factors for its recurrence, and to evaluate new treatment modalities.

Anti-Bacterial Agents↗
PubMed1997

Design of leader sequences that improve the efficiency of the enzymatic synthesis of 2'-amino-pyrimidine RNA for in vitro selection.

The application of nucleic acids obtained by in vitro selection from a large pool of molecules with random sequences in medical diagnosis or therapy requires nucleic acids with enhanced stability in biological fluids. Chemical modifications introduced after selection are likely to alter the structure and the properties of the selected molecules. Therefore, the chemical modifications used must be present throughout the selection. This can be achieved for example by the incorporation of 2'-amino-pyrimidine nucleotides into RNA in the transcription step. Though modified molecules could be transcribed from some generally designed dsDNA templates, the efficiency of transcription and reverse transcription and reverse transcription was very low making this strategy too inefficient. Templates and primers with varying amounts of pyrimidines in the constant flanking region of the RNA molecule were designed and their efficiency in transcription and reverse transcription tested. The obtained 2'-amino-pyrimidine RNA molecules showed enhanced stability in serum and RNAse cocktails. Here we present optimized leader sequences flanking the random core-sequence and reaction conditions that allow the reliable utilization of this modification in in vitro selection.

Base Sequence↗
PubMed1994

Translation of 2'-modified mRNA in vitro and in vivo.

2'-Fluoro- and 2'-amino-2'-deoxynucleoside triphosphates have been used for in vitro transcription of 2'-modified luciferase mRNA. The 2'-modified deoxynucleoside-containing transcripts were tested for the expression of luciferase in X.Laevis oocytes as well as in rabbit reticulocyte lysate. Only 2'-fluoro-2'-deoxy-adenosine-modified mRNA gave rise to luciferase as shown by SDS gel as well as by enzyme activity measurements in vivo as well as in vitro. 2'-Fluoro-2'-deoxy-pyrimidine nucleoside-modified mRNA did not give rise to luciferase activity. However, they directed incorporation of 35S-labeled methionine into peptide fragments in rabbit reticulocyte lysate indicating premature termination of translation. No or only extremely little of such incorporation could be detected with 2'-amino modified transcripts.

Animals↗
PubMed1994

Purification of the synaptic vesicle-binding protein physophilin. Identification as 39-kDa subunit of the vacuolar H(+)-ATPase.

Physophilin is a 36-kDa polypeptide originally identified in synaptic plasma membrane fractions, which binds to synaptic vesicles and has been implicated in vesicle docking and/or exocytosis during neurotransmitter release. Here we report on the purification, amino acid sequence analysis, and subcellular localization of physophilin. Physophilin was enriched from detergent extracts of crude synaptic plasma membranes by a combination of cation exchange and lentil-lectin chromatography. Sequence analysis of peptides generated after sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that physophilin is identical to the 39-kDa subunit (Ac39) of the vacuolar H(+)-ATPase. This was confirmed further by Western blot analysis with an Ac39-specific antiserum and by vesicle binding assays with recombinant Ac39 protein. Subcellular fractionation showed that Ac39 is enriched in synaptic vesicles, with lesser amounts being present in synaptic plasma membrane fractions. These results argue against a docking role of physophilin/Ac39 in synaptic vesicle exocytosis.

Amino Acid Sequence↗
PubMed1990

[The prognostic significance of lymphocyte subpopulations and macrophages in peripheral blood and in bronchoalveolar lavage in AIDS patients with suspected Pneumocystis carinii pneumonia].

In 36 HIV seropositive patients with the clinical manifestation of AIDS and a suspected Pneumocystis carinii infection, lymphocyte subpopulations were analyzed in the peripheral blood (PBL) and compared with the results of the bronchoalveolar lavage (BAL). Of those 36 patients, 29 showed a highly abnormal CD4/CD8 ratio in both the PBL and the BAL. The clinical course of these 29 patients was unpredictable. In seven patients, however, the CD4/CD8 ratio in the BAL was normal or only slightly altered, despite a highly abnormal CD4/CD8 ratio in the PBL. Five of these seven patients improved greatly during the clinical course. The positive outcome of the clinical course was even more strongly correlated with the number of macrophages in the BAL. Twelve of the 36 patients showed normal or only slightly changed numbers of macrophages in the BAL. Eleven of these twelve patients (92%) improved rapidly during antibiotic therapy, while the clinical course was unpredictable in patients with markedly reduced macrophage counts in the BAL.

Acquired Immunodeficiency Syndrome↗
PubMed1981

[Selective induction of tumors in Wistar rats with loop colostomy after administration of methyl-(acetoxymethyl)-nitrosamine (MAOMN) (author's transl)].

A single dose of 7 mg/kg methyl-(acetoxymethyl)-nitrosamine in Wistar rats with double loop colostomy induced adenomas, papillomas, and adenocarcinomas at the site of colostomy in 83% of the treated animals. The mean induction time was 320 days. The pronounced local effect as well as the high tumor yield are discussed in regard to the evident high epithelial sensitivity at the colostomy site.

Adenocarcinoma↗
PubMed1980

[Calcium concentrations in the urine of recurrent stone-formers and their controls (author's transl)].

Over a period of 4--6 weeks the urinary concentrations of (total calcium, ionized calcium, creatinine and osmolarity in recurrent stone-formers and healthy controls were measured in morning, midday and evening urine samples. The mean urinary concentrations of the (total) calcium were in both groups the same. However, 31% of the stone-formers and only 18% of the controls showed a mean calcium concentration > 5 mmol/l. The ionized calcium, on the contrary, was significantly higher in the stone-formers than in the controls. The lower urinary osmolarity of the recurrent stone-formers led to significantly higher Ca/osmolarity and Ca2+/osmolarity ratios; analogously, the quotient Ca2+/creatinine was also significantly raised in stone-formers.

Calcium↗
PubMed1980

[Urinary magnesium and its relationship to calcium in recurrent stone-formers and controls (author's transl)].

Over a period of 4--6 weeks, urine samples were collected three times daily in a group of 16 recurrent stone-formers and in a control group of 11 healthy persons and the urinary concentrations of magnesium, calcium, ionized calcium and creatinine were determined. The Mg-concentrations were distinctly lower in the group of recurrent stone-formers than in the group of healthy controls. The differences were clearly present also in the ratio Ca/Mg, but were diminished in the Mg/creatinine ratio. The Ca2+/Mg-ratio was significantly raised in the group of recurrent stone-formers (p < 0.01) because of the significantly increased Ca2+-concentration and the diminished Mg-concentration in the group of stone-patients. The correlation between the Ca-resp. Ca2+-concentration and the Mg-concentration was in both groups, in the patient and control group, high (r about 0.7).

Calcium↗