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Biomedical subjects

A Klein

Publications and source records attributed to A Klein.

At least 37 records · Page 2Linked to original sources
PubMed1998

The response to domestic violence in a model court: some initial findings and implications.

This study utilized a non-experimental design to obtain information on a full range of domestic violence incidents brought before the Quincy, Massachusetts District Court, a model court. One limitation of previous research on spouse assaults using more sophisticated designs is that the target population has been restricted to specific subgroups of cases thereby limiting subsequent discussions of policy/practice implications of the findings vis-a-vis all spouse assault cases. To address this research "shortfall", we obtained permission from the Quincy District Court to examine all the spouse assault cases brought before the court during a 7-month period (June, 1995, through February, 1996). The findings show that in a full enforcement environment, victims took out restraining orders only against the most violent, criminally abusive men. Most men who were arrested for domestic violence had prior criminal histories for a variety of offenses. Domestic violence offenders appeared to be of two types: those with extensive and diverse criminal histories and those with little or no such involvement. However, active criminal justice intervention against domestic violence offenders appears to be primarily directed toward offenders already active in the criminal justice system.

Adolescent↗
PubMed1998

Expression of cytokeratin-20 in endometrial carcinoma.

OBJECTIVE: Cytokeratins are constituents of the intermediate filaments of epithelial cells which are expressed in various combinations depending on the epithelial type and the degree of differentiation. The recently identified cytokeratin-20 (CK-20) was found with immunohistochemical methods to be expressed in gastrointestinal epithelium, uroepithelial cells, and Merkel cells. Clues were also found for low expression of CK-20 in endometrial carcinoma cells. The aim of this study was to examine whether CK-20 expression can be measured in endometrial carcinoma with the more sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) methods and therefore used as a potential diagnostic tumor biomarker for endometrial carcinoma. METHODS: In the present study we have used RT-PCR methods to determine expression of CK-20 in endometrial epithelial cells. Endometrial specimens were collected from 18 patients with endometrial carcinoma and 22 patients that underwent hysterectomy due to benign diseases. The specimens were prepared for both RT-PCR and immunohistochemical analysis. RNA, of the various cell pellets, was extracted and RT-PCR was performed with CK-20 and CK-19 primers (CK-19 was used as a marker for normal epithelial cells). Immunohistochemistry was carried out with the avidin-biotin-peroxidase complex method on formalin-fixed paraffin sections using CK-20 antibody. RESULTS: CK-20 amplification band (370 bp) was obtained with mRNA extracted from endometrial carcinoma cells of 17 of the patients with endometrial carcinoma (sensitivity, 94.4%). CK-20 was negative in 21 patients with benign endometrial disease (specificity, 91.3%). No positive results were obtained with the immunohistochemical methods. CONCLUSION: These results indicate that RT-PCR of CK-20, because of its high sensitivity, is a potential biomarker for detecting endometrial carcinoma.

Adult↗
PubMed1998

Comparison between levels of trace elements in normal and cancer inoculated mice by XRF and PIXE.

Determination of Rb, Br, Se, Zn, Cu, Fe, and Br/Rb ratio in tissues of mice inoculated with colon and melanoma cancer cells is described. A group of 19 Balb/c mice inoculated with C26 colon carcinoma, 4 C57B1/6 mice inoculated with B16 melanoma, and 13 control mice of both kinds were under investigation. The study was conducted on samples of blood, liver, kidneys, colon, and skin, and the trace element levels in normal and inoculated mice were compared. The inoculation was by subcutaneous injection either at the back or intrafootpad. The blood samples were taken 1, 2, and 3 wk after inoculation, and after 4 wk all the animals were sacrificed. Two nondestructive, complementary analytical methods were used: a modified X-ray fluorescence (XRF) for solid tissue and particle-induced X-ray emission (PIXE) for blood samples. The detection limit (DL) in the PIXE method was 0.35 microg/g dry wt in 600 s counting time and in XRF, 1 microg/g dry sample for Rb, Br, Se and Zn and 2 microg/g for Cu and Fe in 200 s counting time. In all the cases studied, cancerous tissue developed at the site of the injection, and a significant difference in the trace element levels was observed between tissue samples obtained from normal and inoculated mice. The most pronounced effect was an increase in Rb level in the tumor by a factor ranging between 4 and 10 relative to normal tissue, with a corresponding decrease in the Br/Rb ratio (p < 0.05). Smaller changes were found in the Br, Se, Zn, and K levels. The changes in trace element levels in the inner organs were much smaller and seem to be influenced by the site of injection.

Animals↗
PubMed1998

The vhuU gene encoding a small subunit of a selenium-containing [NiFe]-hydrogenase in Methanococcus voltae appears to be essential for the cell.

We developed a general method for the site-specific deletion of gene sequences to obtain new selectable markers in the archaeon Methanococcus voltae. Using a deletion in the hisA gene, a vector was integrated into the chromosome by homologous recombination, thereby reconstituting histidine prototrophy. The vector contained the beta-glucuronidase gene uidA of Escherichia coli as a reporter under the control of an M. voltae promoter that normally drives the expression of a selenium-free [NiFe]-hydrogenase after selenium deprivation. This construct has allowed us to check whether the selenium supply was sufficiently low to induce the transcription of the genes encoding the selenium-free hydrogenases. We tried to introduce a chromosomal deletion of the vhuU gene of the archaeon M. voltae by gene replacement and by keeping the cells under selenium deprivation. The gene vhuU encodes the very small, selenocysteine-containing subunit that is part of the primary reaction center of the Vhu hydrogenase. All transformants bearing the deletion also contained the vhuU wild-type gene. Therefore, the vhuU gene appears to be essential for the cell even under conditions that lead to the induction of the selenium-free homologue Vhc of the Vhu hydrogenase.

Aldose-Ketose Isomerases↗
PubMed1998

Orthotopic liver transplantation in patients with biliary atresia and situs inversus.

Situs inversus (SI) and the polysplenia syndrome (PS) occur relatively frequently in patients with biliary atresia, the largest subgroup of pediatric liver transplantation patients. We present two cases of orthotopic liver transplantation (OLT) in pediatric patients with SI. One had SI totalis, where a normal liver was placed in the left upper quadrant (LUQ) with the right lobe overlying the vertebral column. The second had PS and isolated SI of the liver, and a living-related left-lateral-segment graft was placed in the LUQ. Although multiple, often unpredictable vascular and intestinal anomalies occur frequently in association with SI, particularly in the setting of the PS, these cases, as well as several others recently reported, reveal that these anomalies can be managed successfully by a variety of technical modifications of the standard OLT technique. Likewise, concerns about the placement of a situs solitus liver in the midline or LUQ position of a SI abdomen have proved to be unfounded.

Biliary Atresia↗
PubMed1998

Flagellin genes of Methanococcus vannielii: amplification by the polymerase chain reaction, demonstration of signal peptides and identification of major components of the flagellar filament.

The highly conserved nature of the 5'-termini of all archaeal flagellin genes was exploited by polymerase chain reaction (PCR) techniques to amplify the sequence of a portion of a flagellin gene family from the archaeon Methanococcus vannielii. Subsequent inverse PCR experiments generated fragments that permitted the sequencing of a total of three flagellin genes, which, by comparison with flagellin genes that have been sequenced, from other archaea appear to be equivalent to flaB1, flaB2, and flaB3 of M. voltae. Analysis of purified M. vannielii flagellar filaments by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed two major flagellins (Mr = 30,800 and 28,600), whose N-terminal sequences identified them as the products of the flaB1 and flaB2 genes, respectively. The gene product of flaB3 could not be detected in flagellar filaments by SDS-PAGE. The protein sequence data, coupled with the DNA sequences, demonstrated that both FlaB1 and FlaB2 flagellins are translated with a 12-amino acid signal peptide which is absent from the mature protein incorporated into the flagellar filament. These data suggest that archaeal flagellin export differs significantly from that of bacterial flagellins.

Amino Acid Sequence↗
PubMed1998

O-acetylation of sialic acids.

Sialic acids can be acetylated at the 4, 7, 8 and/or 9 position. Biological roles of these substitutions have been missed until recently because of their low abundance and lability to conventional purification methods. The recent advances in the analysis of sialic acids have allowed to demonstrate that O-acetylation has a selective but widespread distribution. The metabolism of acetylated sialic acids is under the control of two groups of enzymes, O-acetyl transferases and 9-O-acetyl esterases. O-acetyl transferases are difficult to purify, and furthermore, attempts at expression cloning have failed in isolating the true 9-O-acetyl transferase cDNA. This explains that the regulation of the selective expression of O-acetylated sialic acid in not completely understood. Acetylation of sialic acid is expressed on the outer most part of the carbohydrate moiety of membrane and secreted glycoconjugates. This particular location explains why this modification is involved in cell/cell interactions and in the non-immune protection of mucosa.

Acetylation↗
PubMed1998

Cytokeratin 20: a new marker for early detection of bladder cell carcinoma?

PURPOSE: Cytokeratins are constituents of the intermediate filaments of epithelial cells in which they are expressed in various combinations depending on epithelial type and degree of differentiation. Of the 20 known cytokeratins, cytokeratin 19 is expressed in normal urothelium cells, whereas the recently identified cytokeratin 20 (CK-20) is expressed in urothelial carcinoma but not normal urothelium cells. We examine whether CK-20 expression can be used as a bladder tumor marker for transitional cell carcinoma in cells isolated from urine. MATERIALS AND METHODS: The reverse transcriptase polymerase chain reaction method was used to determine expression of CK-20 in cells separated from urine of patients with bladder carcinoma. Cells were obtained from urine of 192 patients stratified into 3 groups of 21 healthy young volunteers without a history of transitional cell carcinoma, 27 with a negative bladder biopsy for transitional cell carcinoma and 144 with bladder transitional cell carcinoma. The parameters were tumor stage and grade, tumor size, number of tumors, urinary cytology and CK-20. RESULTS: CK-20 amplification band (370 base pairs) was obtained with messenger ribonucleic acid extracted from transitional cell carcinoma cells of bladder tumor. CK-20 in the urine samples of the control group was negative (no false-positive results, specificity 100%). Among the 27 patients with pTo disease CK-20 was negative in 20 (specificity 74.1%). In the 7 patients with positive CK-20 histology showed chronic inflammation in 2, atypical hyperplasia in 3 and metaplasia in 1. In 1 patient who had a known history of transitional cell carcinoma the urothelium was normal. Among 144 patients with bladder transitional cell carcinoma CK-20 was positive in 131. Sensitivity of the method was much higher than urinary cytology (91 versus 56.3%, p <0.0001). We demonstrated no correlation between CK-20 and tumor grade. CONCLUSIONS: Our results indicate that CK-20 is a potential marker for bladder cancer. The noninvasive detection method assesses urothelial cells from the voided urine specimen using reverse transcriptase-polymerase chain reaction. The CK-20 marker was significantly more sensitive than urinary cytology.

Adult↗
PubMed1998

Identification of urinary oligosaccharides by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

A new method of urinary oligosaccharides identification by matrix-assisted laser desorption time-of-flight mass spectrometry is presented. The method involves three steps: coupling of the urinary oligosaccharides with 8-aminonaphthalene-1,3,6-trisulfonic acid; fast purification over a porous graphite carbon extraction column; and mass spectrometric analysis. Identification of urinary oligosaccharides is based on the patterns and values of the pseudomolecular ions observed. We report here the patterns in urines from patients with Pompe disease, alpha and beta mannosidoses, galacto-sialidosis, and GM1 gangliosidosis. The protocols described here allowed facile and sensitive identification of the pathognomonic oligosacchariduria present in lysosomal diseases and can be extended to any pathological oligosacchariduria.

Adult↗
PubMed1998

[Diagnosis and therapy of pancreatic pseudocysts in chronic pancreatitis].

Cystojejunostomy is the operation of choice in patients with pancreatic pseudocysts with pain and/or local complications if no resection procedure is necessary. This procedure can be performed safely after 6 weeks with a low morbidity and mortality and good long-term results compared to conservative treatment.

Chronic Disease↗
PubMed1997

The telomere binding protein of Euplotes crassus prevents non-specific transcription initiation but has no role in positioning transcription initiation complexes.

Model substrates mimicking the telomeric as well as the 5'-untranslated regions in front of a 5'-terminal part of a macronuclear gene of Euplotes crassus were transcribed in vitro using cellular extracts. The obtained transcripts were characterized by primer extension and shown to start at the natural initiation points. The situation changed in the absence of telomere binding protein or with substrates lacking functional telomeric sequences. In these cases non-specific transcription was observed. Since it had been previously found that transcription starts are frequently located at an apparently fixed distance from the telomere, a model substrate was constructed which carried a duplication of the non-transcribed region. This resulted in only one transcription start site, the position of which was conserved relative to the start of the open reading frame but moved away from the telomere by the distance of the duplication.

Animals↗
PubMed1997

Changes in the electronic structure around Ni in oxidized and reduced selenium-containing hydrogenases from Methanococcus voltae.

The selenium-containing F420-reducing hydrogenase from Methanococcus voltae was anaerobically purified to a specific hydrogen-uptake activity of 350 U/mg protein as determined with the natural electron acceptor. The concentrated enzyme was used for EPR-spectroscopic investigations. As isolated, the enzyme showed an EPR spectrum with g(xyz) values of 2.21, 2.15 and 2.01. Illumination of such samples at low temperatures led to an EPR spectrum with g(xyz) values of 2.05, 2.11 and 2.29. These spectra are typical for [NiFe]hydrogenases in the active state. Spectra of samples enriched in 77Se showed a hyperfine interaction between the unpaired spin of the nickel ion and the nuclear spin of one 77Se atom before and after illumination. A 90 degree flip of the electronic z-axis is proposed to explain the hyperfine interaction in both states. This has been demonstrated previously only for the F420-non-reducing hydrogenase from M. voltae, where the selenium atom is present as a selenocysteine residue on an unusually small separate subunit [Sorgenfrei, O., Klein, A. & Albracht, S. P. J. (1993) FEBS Lett. 332, 291-297]. The results demonstrate that the three-dimensional structures of the active sites in the selenium-containing F420-reducing and F420-non-reducing hydrogenases from M. voltae are highly similar and hence are not influenced by the unusual subunit structure of the latter enzyme. Oxidized samples containing either natural selenium or 77Se were prepared from the F420-reducing and the selenium-containing F420-non-reducing hydrogenase. Both enzymes exhibited EPR spectra typical for [NiFe]hydrogenases in the inactive 'ready' state. In contrast to the reduced form, no splitting of the nickel-derived signal due to the nuclear spin of 77Se was observed in the oxidized state, indicating that the electronic z-axis is perpendicular to the Ni-Se direction.

Chromatography, Gel↗
PubMed1997

Transport and fate of trifluoroacetate in upland forest and wetland ecosystems.

Although trifluoroacetate (TFA), a breakdown product of chlorofluorocarbon replacements, is being dispersed widely within the biosphere, its ecological fate is largely unknown. TFA was added experimentally to an upland, northern hardwood forest and to a small forest wetland ecosystem within the Hubbard Brook Experimental Forest in New Hampshire. Inputs of TFA were not transported conservatively through these ecosystems; instead, significant amounts of TFA were retained within the vegetation and soil compartments. More TFA was retained by the wetland ecosystem than by the upland forest ecosystem. Using simulation modeling, TFA concentrations were predicted for soil and drainage water until the year 2040.

Adsorption↗
PubMed1997

Lymphoma with multi gene rearrangement on the level of immunoglobulin heavy chain, light chains, and T-cell receptor beta chain.

A unique case with diffuse mixed malignant lymphoma was investigated for gene rearrangement on the level of T-cell receptor (TCR), heavy chain immunoglobulin (Ig), and both light chains. Cell phenotype was examined with immunofluorescence techniques using antibodies against surface immunoglobulins (SIg) and the kappa and lambda light chains. Monoclonal antibodies were used against CD3, CD4, CD5, CD8, CD10, CD19, CD22, HLA-DR, and TdT. Gene rearrangement analysis for monoclonality determination was carried out with restricted DNA (EcoR I and Hind III) hybridized with one of the following 32P-labelled probes: T-cell receptor (TCR beta), immunoglobulin heavy chain (JH), k light chain, and lambda light chain. Phenotyping of the cell population from the excised lymph node (LN) revealed the presence of 66% B-cells and 35% T-cells. Most of the B cells (94%) expressed mu heavy chain only. Expression of both light chains was negligible (k = 7% and lambda = 2%). Gene rearrangement, which indicates monoclonality, was positive on the level of TCR, Ig heavy chain, and both light chains. The data obtained suggests a neoplastic transforming event in lymphoid stem cells, which preceded the subsequent differentiation process into either B or T lymphoma.

Aged↗
PubMed1997

The [NiFe] hydrogenases of Methanococcus voltae: genes, enzymes and regulation.

Methanococcus voltae carries genetic information for four [NiFe] hydrogenases. Two of the hydrogenases are predicted to contain selenocysteine on the basis of in-frame TGA codons, while the genes encoding the two other enzymes contain cysteine codons at homologous positions. Their predicted subunit compositions and their electron acceptor specificities are similar to those of the respective selenium-containing enzymes. The selenium-containing hydrogenases have been purified and characterized. Only one of them reduces the deazaflavin F(420). The activity of the F(420)-nonreducing enzyme is exceptionally high. The selenium atom has been shown by EPR spectroscopy to be a ligand to the Ni atom in the primary reaction centers in both enzymes. The spectroscopic analyses also yielded a description of the electronic configuration around the NiFe center at different oxidation states and in the presence of the competitive inhibitor, CO. The genes encoding the selenium-free hydrogenases are expressed only in the absence of selenium. They are linked by an intergenic region in which regulatory cis elements were defined by employing reporter gene constructs and site-directed mutagenesis.

Journal Article↗
PubMed1997

The TATA-less promoter of hepatitis B virus S gene contains a TBP binding site and an active initiator.

The surface antigen (S) gene promoter, one of the major hepatitis B virus (HBV) promoters, directs the synthesis of a 2.1 kb mRNA which encodes the preS2 and S polypeptides. The preS2/S promoter does not contain a classical TATA box, and transcription regulation of the preS2/S gene has not been fully elucidated. We analysed two regions involved in preS2/S gene transcription of the HBV adw subtype: the diverged TATA box and a putative initiator element. We demonstrated sequence specific promoter activity of the putative TATA-like sequences in the preS2/S gene promoter (-25 to -32 bp). Using end labeled synthetic oligonucleotides we observed specific binding of nuclear extracts to the diverged TATA sequence, that was significantly reduced using a mutated oligonucleotide. Specific binding of yeast TBP to the diverged TATA sequence was shown which was increased in the mutant containing a classical TATA box. We analysed the proposed initiator (Inr) sequence of the preS2/S promoter region (-13 to -16 bp). Deletion of the inr element markedly reduced promoter activity as assessed by CAT expression. Gel shift assays showed specific binding of nuclear extracts to wild type but not to mutant Inr. Expression studies with double mutants of the diverged TATA and the Inr element established that both elements are active in transcription regulation.

Base Sequence↗
PubMed1997

Critical comparison of indices and threshold values for assessing placenta performance using Doppler ultrasound.

To determine the most appropriate index and an optimal cutoff value for obstetric Doppler ultrasound, the umbilical and uterine arteries of 467 patients were examined during the third trimester using an Acuson 128 color Doppler system. Doppler ultrasound detection of chronic placental insufficiency with fetal growth retardation and acute placental insufficiency with subpartal asphyxia were selected as criteria. A birth weight below the 10th percentile (using Hohenauer's percentiles) was taken as the parameter for the former and a 5-minute Apgar score of < 8 for the latter criterion. For each artery, two risk groups were studied: 103 patients with chronic and 27 patients with acute placental insufficiency. Using EROC curves, the prediction of chronic and acute placental insufficiency was computed for six Doppler indices (maximum systolic, mean [TAMX] and maximum end-diastolic velocities, S/D ratio, RI, PI) and 10 threshold values per index (the 1st to 50th percentiles for the qualitative indices and the 50th to 99th percentiles for the quantitative indices). The following results were obtained: (1) the development of chronic placental insufficiency was predicted best in Doppler examinations of the umbilical artery by calculating the PI with the 60th percentile as the threshold value, and in examinations of the uterine artery by determining the S/D ratio with the 90th percentile; 2nd (2) acute placental insufficiency was predicted best by calculating the mean blood flow velocity (TAMX) in the umbilical artery, with the 50th percentile as the ideal cutoff value; in examinations of the uterine artery the best results were obtained by determining the S/D ratio with the 90th percentile as cutoff value. Three conclusions may be drawn from the results: (1) taken overall, the qualitative Doppler parameters (S/D ratio, RI, PI) are superior to the quantitative parameters (maximum systolic, mean [TAMX] and maximum end-diastolic velocity) in the detection of both chronic and acute placental insufficiency; (2) in Doppler examinations of the umbilical artery the optimal threshold value is in the region of the 60th, and in examinations of the uterine artery in the region of the 90th, percentile; and (3) chronic placental insufficiency was detected better than the acute form; examinations of the umbilical artery yielded more explicit data than those of the uterine artery.

Adult↗