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Biomedical subjects

G Kramer

Publications and source records attributed to G Kramer.

At least 91 records · Page 5Linked to original sources
PubMed1997

Lessons learned from the study of immigrants to Israel from areas of Russia, Belarus, and Ukraine contaminated by the Chernobyl accident.

During the past 6 years, immigration to Israel of 700,000 persons from the former Soviet Union (FSU) included about 140,000 from radiocontaminated regions of Belarus, Ukraine, and Russia near Chernobyl. In Beer Sheva, a major center for immigrant absorption in Israel, a primary objective was to evaluate their health status and to refer them for care. 137Cs levels in 1228 men, women, and children were measured with a portable whole-body counter. Whole-body counts showed clear correlation with the degree of 137Cs ground contamination in previous regions of residence. The population could thus be sub-divided according to degree of exposure, based on previous regions of residence. The thyroid status of 300 local immigrant children was evaluated because of the increased risk of childhood thyroid cancer in the regions from which they came. This group was subdivided into comparative groups of children who came from less and more contaminated areas according to the International Atomic Energy Agency soil 137Cs contamination maps. Enlarged thyroids were found in about 40% of both groups. One 12-year-old girl from Gomel had a malignant papillary carcinoma. Thyroid-stimulating hormone levels, though within normal limits, were significantly greater (p < 0.02) for girls from high exposure regions. Liquidators showed significant increases in serum clastogenic factor and in the number of circulating glycophorin A-mutated red cells. In studies of over 700 people from both radiocontaminated and unaffected regions of the FSU, evidence for posttraumatic stress disorder was found more frequently in persons coming from the more contaminated areas.

Blood Pressure↗
PubMed1997

Serial tissue polypeptide specific antigen determination in the followup of hormone treated carcinoma of the prostate.

PURPOSE: We determined the impact of serum cytokeratin-18-related tissue polypeptide specific antigen (TPS) in monitoring hormone treated carcinoma of the prostate. MATERIALS AND METHODS: From 1991 to 1996, serial TPS and prostate specific antigen (PSA) determinations (3,882) in 443 hormone treated prostate carcinoma patients were correlated with the clinical course for a mean of 22 months. RESULTS: Elevated TPS levels were significantly associated with disease progression in hormone treated stage M1 carcinoma of the prostate (p = 0.001), even in high grade, PSA negative tumors. Post-therapy TPS declines following second line therapy in hormone refractory prostate cancer patients (92) correlated significantly with subjective response (p = 0.001, PSA p = 0.02) and progression-free survival time (r(s) = -0.76, PSA r(s) = -0.32). A TPS decrease of more than 50% coincided with palliation in 90% of patients (PSA 64%) and predicted the best chance of a longer progression of free survival (p < 0.00005, PSA p = 0.036). Vice versa, rising TPS levels (more than 20%) coincided with subjective response in only 1 of 37 patients (PSA 9 of 33). CONCLUSIONS: TPS may be a useful adjunct to PSA in monitoring hormone refractory, metastasized prostate cancer.

Aged↗
PubMed1996

Binding of an N-terminal rhodanese peptide to DnaJ and to ribosomes.

A peptide corresponding to the N-terminal 17 amino acids of bovine rhodanese was fluorescently labeled with a coumarin derivative at its primary amino group(s) and then purified by high performance liquid chromatography. This peptide interacted with the molecular chaperone DnaJ in the absence of other chaperones and ATP. In the presence of ATP, the molecular chaperone DnaK bound to the DnaJ-peptide complex, but not to the peptide alone. The chaperone GrpE appeared to cause the release of the peptide bound to the ternary complex in the presence of ATP but not in the presence of ADP. This nucleotide apparently stabilized the complex. The peptide also bound to salt-washed Escherichia coli 70 S ribosomes, specifically to 50 S ribosomal subunits, not to 30 S subunits. DnaJ plus DnaK interacted with the peptide on the ribosome. GrpE caused dissociation of the peptide from the ribosome; ATP was required for this reaction. It was inhibited by ADP. A comparable series of chaperone-mediated reactions is assumed to occur with the N-terminal segment of the nascent polypeptide to facilitate its folding on ribosomes.

Adenosine Diphosphate↗
PubMed1996

Stable expression in HEK-293 cells of the rat alpha3/beta4 subtype of neuronal nicotinic acetylcholine receptor.

The alpha3/beta4 subtype of neuronal nicotinic acetylcholine receptor (nAChR) was stably expressed in human embryonic kidney (HEK) 293 cells that co-expressed a voltage-gated Ca2+ channel. alpha3/beta4-nAChR-expressing clones were identified using the fura-2 Ca2+ imaging technique, and were further characterised by single-cell and whole-cell patch-clamp studies. Acetylcholine (ACh) induced fast activating currents which showed desensitisation and inward rectification. The conductance of the ACh-activated channel was 29 pS. The order of potency of the nicotinic agonists tested was cytisine approximately = nicotine > acetylcholine. The EC50 value for ACh was 145 microM; the Hill coefficient was close to 2. The currents elicited by ACh were effectively blocked by nicotinic antagonists, but not by the muscarinic antagonist atropine. These properties are comparable to the pharmacological and physiological profile of ganglionic nicotinic receptors and type III currents of cultured hippocampal neurons.

Acetylcholine↗
PubMed1996

Effect of multimerization of human and recombinant von Willebrand factor on platelet aggregation, binding to collagen and binding of coagulation factor VIII.

The smallest circulating von Willebrand factor (vWF) molecule is a dimer composed of two identical subunits containing binding sites for heparin, collagen, platelet glycoproteins and coagulation factor VIII (FVIII). Interdimeric disulfide linking leads to multimers composed of up to 40 dimers. vWF serves as a carrier of FVIII and is required for normal interactions of platelets with the subendothelium of the injured vessel wall. Von Willebrand factor was purified from human plasma cryoprecipitate and fermentation supernatant of recombinant CHO cells by anion exchange chromatography. Heparin affinity chromatography was used to isolate vWF polymers of different degree of multimerization. Analysis of collagen binding and platelet aggregation revealed that these activities increase with increasing degree of multimerization of vWF. Binding of FVIII to vWF was studied by real-time biospecific interaction analysis and surface plasmon technology. The binding data showed that the binding of FVIII is independent of vWF multimerization. Using recombinant FVIII and recombinant vWF, real-time biospecific interaction analysis resulted in a potential stoichiometry of 2 to 2.5 vWF-subunits per bound FVIII molecule. The kinetic analysis of the vWF-FVIII interaction resulted in a binding rate constant of about 3 x 10(6) M-1 s-1 and an equilibrium dissociation constant of about 0.4 x 10(-9) M.

Animals↗
PubMed1996

Maximal external electrical stimulation for treatment of neurogenic or non-neurogenic urgency and/or urge incontinence.

Maximal electrical stimulation by intravaginal or intra-anal electrodes was used for treatment of 75 patients with complaints of urgency and/or urge incontinence. The patient group consisted of 51 women and 24 men. A neurogenic background was present in 30 of the women who had a diagnosis of multiple sclerosis, in the other 45 patients the pathology was idiopathic in nature. After 3 weeks of maximal electrical stimulation treatment, composed of 15 sessions of 20 minutes duration, 59% of the patients had urodynamic and subjective improvement and an additional 40% only subjective improvement. One patient found no benefit after this treatment. The effect lasted for at least 2 years in 64% of the idiopathic group. In the multiple sclerosis group relapse occurred within about 2 months. Re-treatment of the failures was successful again immediately; the multiple sclerosis patients do need daily home stimulation treatments.

Adolescent↗
PubMed1996

Restoration of micturition in patients with acontractile and hypocontractile detrusor by transurethral electrical bladder stimulation.

The aim of transurethral electrical bladder stimulation (TEBS) treatment in patients with diminished detrusor contractility is to attain complete voiding, i.e., micturition without residual urine, which is under volitional control. In contrast to other types of electrical bladder stimulation, the physiological basis for this kind of treatment is sensitizing of the bladder mechanoreceptor afferents. The latency of afferent stimuli in normal conditions indicates that myelinated A-delta-fibers are used for neurotransmission from these mechanoreceptors. Forty-eight patients with hypocontractile or acontractile detrusor underwent intravesical electrical stimulation. All patients had a history pointing to neurogenic pathology. Forty patients had an acontractile and 8 a hypocontractile bladder. Prior to therapy, the mean residual urine volume was 461 ml. After stimulation, 32 of 48 patients were able to void with a mean residual of 57 ml. Detrusor contraction was achieved in 39% and bladder sensation was perceived by 75% of patients who failed these conditions before treatment. Following therapy, 19 of 35 patients were able to empty their bladder without the previously needed catheterization. Side effects were epididymitis in 1 and cystitis in 7 patients.

Adult↗
PubMed1996

Are T cells from healthy heart really only passengers? Characterization of cardiac tissue T cells.

Numerous studies have dealt with occurrence of dendritic cells in various nonlymphoid organs such as kidney, liver or heart, whereas lymphocyte patterns in these organs have not been analyzed in detail. In the present study, leukocytes were quantified as cells/mm2 in the perivascular, interstitial and parenchymal tissue sections of normal heart. We measured an overall mean leukocyte count in normal heart tissue of 17.0 +/- 2.7 CD45+ leukocytes/mm2, 9.1 +/- 1.8 thereof being CD4+ T-helper cells (Th). By comparison, CD8+ T-cytotoxic/suppressor cells (Ts) and CD14+ macrophages each accounted for only approximately 2.5 cells/mm2, and CD20+ B cells for only 1.3 cells/mm2. These T cells were further characterized as either CD45RA+ naive T cells or as CD45RO+ memory T cells. Segmentation of the tissue as defined in Section 2 yielded an ascending number of CD45RO+ memory T cells from perivascular (0.4 +/- 0.2 cells/mm2) through parenchymal (12.8 +/- 3.0 cells/mm2) to interstitial (21.0 +/- 5.3/mm2). By contrast, the number of CD45RA+ and Leu-8+ cells decreased from perivascular to parenchymal. Peripheral T cells showed a reverse pattern of CD45RA/CD45RO antigen expression. Only approximately 3% of T cells expressed activation markers IL-2R and IL7R. Our data demonstrate that the majority of T cells in normal heart tissue are resting memory tissue T cells and are not contaminating T cells from the peripheral blood. The increase in CD45RO+ cells from perivascular to parenchymal with a corresponding decrease in CD45RO+ and Leu-8+ heart-tissue T cells argues in favor of T-cell traffic in normal heart tissue.

Antigens, CD↗
PubMed1996

Tissue polypeptide-specific antigen in renal cell carcinoma.

OBJECTIVES: The usefulness of serum tissue polypeptide-specific antigen (TPS), a cytokeratin 18-associated marker, in renal cell carcinoma (RCC) was assessed in vitro and in vivo. METHODS: Indirect immunoperoxidase staining for TPS expression was performed on frozen sections of normal renal tissue and RCC specimens. By using a monoclonal TPS immunoradiometric assay, serum TPS concentrations were analyzed in 82 healthy controls, in 20 patients with locoregional RCC before and after surgery and in 18 patients with advanced disease following surgery receiving immunotherapy with interferon-gamma. RESULTS: Using immunohistochemistry, TPS was found to be expressed by both normal and cancerous renal epithelial cells. The mean TPS concentrations in 82 healthy controls was 56 +/- 49 U/1 with a 95% percentile of 78.5 U/1. Out of 20 patients with locoregional RCC, 8 presented with elevated values (mean 168 +/- 82 U/1) above the cut-off level (78.5 U/1, sensitivity 40%) which dropped to normal within 2 weeks after surgery. During a follow-up period of 1 year, none of the patients presented with tumor recurrence and TPS concentrations remained low (mean 52 +/- 36 U/1). In 18 patients receiving interferon-gamma therapy, serum TPS concentrations were monitored over a period of 12 months. In 5/18 patients, baseline levels were within the normal range (mean 37 +/- 21 U/1); interestingly, these at the same time were the only responders to immunotherapy (n = 2) or at least showed stable disease (n = 3). Response to therapy was reflected by low serum TPS levels (mean 28 +/- 23 U/1) over the entire observation period. Thirteen patients suffered progressive disease during therapy, all of them exhibiting significantly elevated (p < 0.005) pretherapeutic TPS concentrations (mean 186 +/- 124 U/1) that remained equally elevated throughout therapy (mean 192 +/- 102 U/1), reflecting tumor progression. CONCLUSIONS: TPS might have some clinical value as prognostic marker in RCC, possibly by reflecting the proliferative tendency of the tumor.

Adult↗
PubMed1995

Phenotypic patterns of mononuclear cells in dilated cardiomyopathy.

BACKGROUND: Immunological factors in the pathogenesis of idiopathic dilated cardiomyopathy (IDC) were suggested previously on the basis of the demonstration of mononuclear cell infiltrates and autoantibodies against the myocardium. The present study investigated whether tissue leukocyte subpopulations isolated from hearts with IDC (n = 6) differ in phenotype from those of tissues without IDC (n = 7). METHODS AND RESULTS: Leukocytes were quantified as reactive cells per square millimeter in perivascular, interstitial, and parenchymal tissue sections. Freshly isolated heart-tissue T cells and peripheral-blood T cells from the same patients were analyzed by triple staining and flow cytometry to identify T-cell subpopulations as well as their states of differentiation (expression of CD45RA and Leu-8 versus CD45RO) and activation (IL-2R, IL-7R, very late antigen-1, HLA-DR). All types of infiltrating cells (T cells, B cells, macrophages, granulocytes) are increased in hearts with IDC compared with normal hearts, but only CD8+ T cells and macrophages are increased relative to the other leukocyte subpopulations. CD45RO+/CD45RA-/Leu-8- cells constitute the majority of heart-tissue T cells in both normal hearts and hearts with IDC. Strikingly, hearts with IDC are infiltrated by eightfold greater numbers of perivascularly located IL-2R(+)- (26% of all T cells) and CD45RO(+)-activated memory T cells; moreover, in contrast to normal heart, approximately 40% of both CD4+ and CD8+ heart-tissue T cells express activation markers. CONCLUSIONS: Both normal hearts and hearts with IDC are populated by leukocytes. The quantitative increase in IDC, associated with a dramatically altered activation status of heart-tissue T cells, suggests a direct role of infiltrating leukocytes in the pathogenesis of IDC.

Cardiomyopathy, Dilated↗
PubMed1995

Folding of an enzyme into an active conformation while bound as peptidyl-tRNA to the ribosome.

Rhodanese bound to bacterial ribosomes as peptidyl-tRNA can be folded into an enzymatically active conformation by generating C-terminal extensions of the wild-type enzyme. Rhodanese was synthesized by coupled transcription/translation in a cell-free Escherichia coli system from plasmids containing the coding sequences for the wild-type enzyme or its C-terminally extended mutants. Two proteins with extensions of 23 amino acids or longer were enzymatically active while bound to the ribosomes whereas wild-type protein and a 13-amino acid extension were not. All forms of the enzyme were active after termination and release of the full-length protein from the ribosomes. All five of the bacterial chaperones were required to substantially increase the specific enzymatic activity of the extended rhodanese while the nascent protein was bound to ribosomes. The results provide direct support for the hypothesis that proteins acquire tertiary structure as they are formed in ribosomes.

Cell-Free System↗
PubMed1995

Elongation and folding of nascent ricin chains as peptidyl-tRNA on ribosomes: the effect of amino acid deletions on these processes.

Ricin A-chain was used as a test protein to study the effects of deletion of codons on the ribosomal synthesis, release and chaperone-mediated folding of the proteins. Synthesis of wild-type ricin and five mutant proteins was carried out in an Escherichia coli cell-free coupled transcription/translation system from otherwise identical non-linearized plasmids. The deletions involved small numbers of contiguous amino acid residues at different points from the N terminus to the C terminus of the wild-type protein. Deletion of the N-terminal 20 amino acid residues caused a 45% reduction in total protein synthesis whereas deletion of the next three amino acid residues caused a 1.5-fold increase in synthesis compared with wild-type with an accumulation of full-length polypeptides as peptidyl-tRNA in the ribosomal P site. Intermediate levels of synthesis and release were seen with the other three mutants. Enzymatic activity was detected only with wild-type protein and a mutant lacking the C-terminal five amino acid residues. These were the only ricin species in which chaperone-dependent reactions could be detected by fluorescence from coumarin incorporated with methionine at the N terminus of the proteins. By using sparsomycin to block termination of full-length peptidyl-tRNA, it was demonstrated that the chaperone-mediated reactions detected by fluorescence occur on the ribosomes and involve folding of the nascent protein as peptidyl-tRNA. The results presented provide a direct demonstration of two points of fundamental importance: folding of nascent proteins involving chaperone-mediated reactions can occur on ribosomes and is directly related to the conformation of the native enzyme. Deletion of amino acid residues at different points from the N terminus to the C terminus affects the reactions of elongation, chaperone-mediated folding and release of full-length protein.

Cell-Free System↗
PubMed1995

The importance of the N-terminal segment for DnaJ-mediated folding of rhodanese while bound to ribosomes as peptidyl-tRNA.

Two lines of evidence indicate the importance of the N-terminal portion of rhodanese for correct folding of the nascent ribosome-bound polypeptide. A mutant gene lacking the codons for amino acids 1-23 of the wild-type protein is expressed very efficiently by coupled transcription/translation on Escherichia coli ribosomes; however, the mutant protein that is released from the ribosomes is enzymatically inactive. The mutant protein does not undergo the reaction that is promoted by the bacterial chaperone, DnaJ, which appears to be essential for folding of ribosome-bound rhodanese into the native conformation. The effect of DnaJ is monitored by fluorescence from coumarin cotranslationally incorporated at the N terminus of nascent rhodanese. Secondly, a synthetic peptide corresponding to the N-terminal 17 amino acids of the wild-type protein interferes with the synthesis of wild-type rhodanese but has much less effect on the synthesis of the N-terminal deletion mutant. The N-terminal peptide inhibits the effect of DnaJ on the nascent wild-type rhodanese and blocks the chaperone-mediated release and activation of ribosome-bound full-length rhodanese polypeptides that accumulate during in vitro synthesis. The results lead to the hypothesis that the N-terminal segment of rhodanese is required for its chaperone-dependent folding on the ribosome.

Escherichia coli Proteins↗