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G Klein

Publications and source records attributed to G Klein.

At least 289 records · Page 16Linked to original sources
PubMed1994

Juxtaposition of N-myc and Ig kappa through a reciprocal t(6;12) translocation in a mouse plasmacytoma.

Nearly all mouse plasmacytomas (MPCs) carry an Ig/myc translocation. Any one of the three Ig loci may participate, while the myc contribution has been limited to c-myc, excluding other members of the myc gene family. The same is true for the other two known Ig/myc translocation-carrying tumors, Burkitt's lymphoma and rat immunocytoma. It is believed that the Ig/myc juxtaposition plays a decisive, rate limiting role in the genesis of the three tumors, acting through the constitutive activation of myc that makes it refractory to normal regulation. Here we describe the molecular analysis of a unique t(6;12)(CI;B) translocation that we previously identified in an exceptional MPC that expressed N-myc but not c-myc. We now show that the translocation led to the juxtaposition of N-myc and Ig kappa. This is the first case of an Ig/myc-carrying tumor that involves N-myc rather than c-myc. These findings suggest that the translocation may already have occurred at the pro- or pre-B cell stage at which N-myc is open for transcription. According to this interpretation, constitutive activation of N-myc would suppress the expression of c-myc, but would not interfere with the differentiation of the pro-B cell into a fully mature plasma cell. Its tumorigenic influence would become manifest only at the time when the cell would normally be programmed to leave the cycling compartment, in connection with its terminal differentiation.

Animals↗
PubMed1994

Nonrandom loss of human chromosome 3 fragments from mouse-human microcell hybrids following progressive growth in SCID mice.

Microcell hybrid lines of A9 mouse fibrosarcoma containing complete or partially deleted human chromosomes 3 (chr. 3) were inoculated into SCID mice. Cell lines derived from the tumors were examined by fluorescent in situ hybridization for the status of the transferred human chromosome and by PCR for marker loss. The SCID tumors arising after the inoculation of 10(5) cells were passaged serially in vivo and regularly showed loss of four markers; D3S1029 (3p21.3-21.2), AP20R (3p22-21.3, D3S32 (3p21.3-p21.2), and THRB (3p24). This regularly deleted region is bordered by markers GNA12 (3p21.1-p21.3) and VHL (3p25) that were maintained in a fraction of tumors. Fragments derived from the long arm of chromosome 3 and corresponding markers in the 3q26-q28 region were retained in all tumors. Our findings may be related to the postulated presence of tumor suppressor genes in the 3p24-p21 region as indicated by the frequent deletion of this region in renal and small cell lung carcinomas and other solid tumors. The technically cumbersome identification of suppressor genes may be supplemented by an "elimination test" based on analogous principles.

Animals↗
PubMed1994

Rapid mapping of NotI linking clones with differential hybridization and Alu-PCR.

For construction of a NotI restriction map of the human genome, the isolation and mapping of unique NotI linking clones represent important and critical steps. Recently we have shown that an Alu-PCR approach can be used for isolation of NotI linking clones from defined regions of the chromosomes. This represents a useful method for isolating and analyzing a small number of clones, but it would be laborious to use it for mapping many NotI linking clones simultaneously. Here we suggest another modification of Alu-PCR for rapid concurrent mapping of many NotI linking clones. The results clearly demonstrate the utility of this approach. Seventy-one random NotI linking clones were analyzed. Among them, 65 clones (91.5%) were correctly selected and mapped using this approach. With differential hybridization and Alu-PCR, a significant portion of all human NotI linking clones (> 30%) can be rapidly mapped to particular chromosomes or to defined regions of these chromosomes.

Animals↗
PubMed1994

Immune response to different sequences of the EBNA I molecule in Epstein-Barr virus-related disorders and in autoimmune diseases.

Epstein-Barr virus (EBV) infection is associated with production of autoantibodies. The N-terminal 35-58 sequence of EBNA I, one of the nuclear antigens encoded by EBV, is highly homologous to the C-terminal 95-119 region of the ribonucleoprotein SmD. Autoantibodies specific for SmD are present only in systemic lupus (SLE) sera and are therefore considered a serological marker of SLE. We measured antibodies to the EBNA I 35-58 sequence in EBV-related diseases and in autoimmune disorders. Antibodies to the EBNA I 35-58 peptide were present in 30% of normal sera, 12% Burkitt lymphoma, 22% infectious mononucleosis, 25% rheumatoid arthritis, 38% SLE and 33% Sjogren's syndrome. Antibodies to the SmD 95-119 peptide were detectable in 32% of SLE sera, 17% infectious mononucleosis and 12% Burkitt lymphoma. The specificity of anti-EBNA I 35-58 antibodies affinity-purified from nine sera was analysed by means of an inhibition assay. Only anti-EBNA I 35-58 antibodies affinity-purified from SLE sera have a similar affinity for the viral peptide and the SmD C-terminal one; they also bind the recombinant SmD in western blot. The results indicate that antibodies to EBNA I 35-58 are produced in normals, in EBV-related diseases and in autoimmune disorder, but only SLE sera contain anti-viral antibodies cross-reactive with an autoantigen.

Amino Acid Sequence↗
PubMed1994

Hypersomy of chromosome 15 with retrovirally rearranged c-myc, loss of germline c-myc and IgK/c-myc juxtaposition in a macrophage-monocytic tumour line.

From a lymphoid tumour induced by 7,12-dimethylbenz-[a]-anthracene (DMBA) + methyl-N-nitrose-N-urea (MNU) in an [AKR Rb(6.15) x CBAT6T6]F1 mouse, a macrophage- monocyte line (KT-10) was isolated. Following ethyl methanesulfonate (EMS) treatment, a bromodeoxyuridine (BUdR) resistant subline was selected. Serial propagation of this line in vitro in the presence of BUdR (28 months) with periodic cytogenetic and molecular examinations, has led to the definition of four successive stages. During stage I, the cells were trisomic for chromosome 15. They contained Rb(6.15) and Rb(del6.15) of AKR and T(14;15) of CBA origin. Southern blotting showed the presence of both germline (G) and rearranged (R) c-myc. At stage II, Rb(del6.15) has duplicated. Both Rb(6.15) and T(14;15) persisted together with G-myc and R-myc. In stage III, the CBA-derived T(14;15) was lost, in parallel with G-myc. At this stage, a Dic.In(6.15) was detected. One of its arms was cytogenetically identical with the long arm of In(6.15) in the variant IgK/myc translocations. This chromosome carried R-myc and IgK in juxtaposition, as indicated by comigration on pulsed field electrophoresis (PFGE). At stage IV, the R-myc carrying AKR-derived chromosome 15s were present in six copies. Possible relationships between the increasing R/G myc ratio and changed growth characteristics in vivo and in vitro are discussed.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Epstein-Barr virus (EBV)-encoded membrane protein LMP1 from a nasopharyngeal carcinoma is non-immunogenic in a murine model system, in contrast to a B cell-derived homologue.

Epstein-Barr virus (EBV)-encoded LMP1 gene derived from a nude mouse passaged nasopharyngeal carcinoma (NPC) of Chinese origin (C-LMP1) and its B cell (B95-8 prototype)-derived counterpart (B-LMP1) were compared for their ability to induce tumour rejection in a mouse mammary adenocarcinoma system. Each of the two LMP1 genes was introduced individually by retroviral vectors into a non-immunogenic mammary carcinoma line, S6C, that originated in an ACA (H-2f) mouse. Syngeneic ACA mice were immunised for 3 consecutive weeks with irradiated B- or C-LMP1 expressors or control cells. The immunised and control mice were then challenged with graded numbers of viable cells from the corresponding cell line. Only the B-LMP1 expressing cells were highly immunogenic. Up to 10(5) cells were rejected in pre-immunised mice, whereas at least 10(2) cells grew in non-immunised controls. No rejection response was detected against the C-LMP1 expressing cells which grew equally well in control and immunised mice, with a minimum inoculum of 10(2) cells in the majority of the clones. In a previous study, we found numerous sequence differences between B- and C-LMP1. The question of whether any of these differences is related to the non-immunogenicity of C-LMP1 needs further investigation. Meanwhile, our findings raise the possibility that the NPC cells may escape host rejection by the development of a non-immunogenic LMP1 variant under the impact of immunoselection.

Animals↗
PubMed1994

The electrophysiologic effects of volatile anesthetics and sufentanil on the normal atrioventricular conduction system and accessory pathways in Wolff-Parkinson-White syndrome.

BACKGROUND: The effects of volatile agents and sufentanil anesthesia on the electrophysiologic properties of the accessory pathway and on the incidence of intraoperative tachyarrhythmias in patients with Wolff-Parkinson-White syndrome are unknown. Therefore, we studied these agents for their use in patients undergoing ablative procedures or requiring a general anesthetic for other surgeries. METHODS: Twenty-one patients with Wolff-Parkinson-White syndrome undergoing surgical ablation were anesthetized with sufentanil (20 micrograms/kg), lorazepam (0.06 mg/kg), and vecuronium (20 mg). After sternotomy, the electrophysiologic study during antegrade stimulation consisted of the effective refractory period of the right atrium, atrioventricular node, and accessory pathway; the shortest cycle length of the atrioventricular node and accessory pathway; and the coupling interval. During retrograde stimulation, the effective refractory period of the right ventricle and accessory pathway and the shortest cycle length of the accessory pathway were measured and compared to preoperative electrophysiologic values. Patients then were randomized to receive 1 MAC of halothane, isoflurane, or enflurane, and the electrophysiologic study was repeated. RESULTS: Sufentanil-lorazepam caused mild prolongation (P < 0.05) of the effective refractory period of the accessory pathway and the shortest cycle length of the atrioventricular node. Enflurane and isoflurane significantly prolonged all parameters related to refractoriness during antegrade conduction, with enflurane having the largest effect. During retrograde conduction, isoflurane prolonged the effective refractory period of the right ventricle and accessory pathway and the shortest cycle length of the accessory pathway, whereas enflurane prolonged only the accessory pathway effective refractory period and shortest cycle length. Halothane had the least effect on refractoriness, causing significant prolongation of the atrioventricular node effective refractory period and the shortest cycle length of the accessory pathway only during antegrade conduction. The coupling interval, a measure of the period of vulnerability to supraventricular tachycardia, was prolonged only by halothane and isoflurane. Supraventricular tachycardia was still obtainable in all patients. CONCLUSIONS: Sufentanil-lorazepam has no clinically significant effect on the electrophysiologic expression of the accessory pathway. Of the volatile agents, enflurane most, isoflurane next, and halothane least increased refractoriness within the accessory and atrioventricular pathways. Therefore, administration of these volatile agents during ablative procedures may confound interpretation of postablative studies used to determine the success of ablation treatment. Conversely, in patients with preexcitation syndrome requiring general anesthesia for nonablative procedures, volatile agents may reduce the incidence of perioperative tachyarrhythmias because of their effects on refractoriness. Enflurane would be the agent of choice because it increases refractoriness the most without prolonging the coupling interval.

Adolescent↗
PubMed1994

Clonality, expression and methylation patterns of the Epstein-Barr virus genomes in lethal midline granulomas classified as peripheral angiocentric T cell lymphomas.

We analysed the terminal repeats of Epstein-Barr virus (EBV) in DNAs isolated from six lethal midline granuloma (LMG) biopsies. A single fused terminal fragment could be detected in each case, indicating that these angiocentric peripheral T cell lymphomas represent clonal proliferations of cells infected with EBV on a single occasion. Using reverse transcriptase-PCR, we detected EBV nuclear antigen (EBNA) 1 and latent membrane protein (LMP) 1, but not EBNA 2 messages in LMG biopsy RNAs. The splicing pattern of the EBNA 1 message was consistent with the usage of a promoter localized in the BamHI F fragment (F promoter). The BamHI W fragment repeats and LMP-coding sequences were highly methylated in all cases. In contrast, the LMP regulatory sequences were found to be hypomethylated or partially methylated, as in LMP-expressing nasopharyngeal carcinomas.

Antigens, Viral↗
PubMed1994

Shortening of fast pathway refractoriness after slow pathway ablation. Effects of autonomic blockade.

BACKGROUND: Shortening of the anterograde effective refractory period (ERP) of the fast pathway has been reported after radiofrequency ablation of the slow pathway. We hypothesized that ERP shortening may be related to autonomic changes, possibly catecholamine release, as a result of ablation. METHODS AND RESULTS: To test this, 10 consecutive patients with atrioventricular node reentry undergoing slow pathway ablation were given autonomic blockade before the ablation procedure. This was achieved by atropine 0.03 mg/kg and propranolol 0.15 mg/kg IV supplemented by half the initial dose after ablation and before the final study. A control group of 10 patients underwent the protocol without autonomic blockade. Before ablation, autonomic blockade did not alter the ERP of either the fast pathway (295 +/- 22 versus 298 +/- 26 milliseconds) or the slow pathway (264 +/- 36 versus 269 +/- 38 milliseconds). Autonomic blockade obscured dual pathway physiology in 2 patients and brought it out in another 2 without dual pathway physiology initially. Slow pathway ablation shortened the ERP of the fast pathway for the group as a whole (331.5 +/- 54 versus 305.5 +/- 60 milliseconds, mean +/- SD, n = 20, P < .04). There was no difference in degree of ERP shortening in control patients (23.5 +/- 58 milliseconds) or autonomic blockade patients (25.5 +/- 52 milliseconds). CONCLUSIONS: These data suggest that shortening of the ERP of the fast pathway after slow pathway ablation is not mediated by autonomic changes.

Adult↗
PubMed1994

Role of mesenchymal nidogen for epithelial morphogenesis in vitro.

Recent biochemical studies suggested that the extracellular matrix protein nidogen is a binding molecule linking together basement membrane components. We studied its expression and role during development. By immunofluorescence and northern blotting, nidogen was found early during epithelial cell development of kidney and lung. Yet, in situ hybridization revealed that nidogen was not produced by epithelium but by the adjacent mesenchyme in both organs. Binding of mesenchymal nidogen to epithelial laminin may thus be a key event during epithelial development. This is supported by antibody perturbation experiments. Antibodies against the nidogen binding site on laminin B2 chain perturbed epithelial development in vitro in embryonic kidney and lung. Mesenchymal nidogen could be important for early stages of epithelial morphogenesis.

Animals↗
PubMed1994

[Microbiological quality of fresh and stored ground meat from commercial production].

In the last quarter of 1993 we investigated 295 samples of minced meat on 59 days of production (5 samples each day). EC-regulations (88/657/EEC, changed by 92/110/EEC) were considered. We looked for the total aerobic count, E. coli, Staph. aureus and Salmonella. Factors that could influence the results were examined as day of sampling, storage under defined conditions, ph-value etc. Most important for the microbiological quality of the product was the quality of the processed meat. In most cases samples fulfilled the strict microbiological requirements of the EC-regulation. After storage for 2 days at 2 degrees C there was no detectable alteration of the microflora of minced meat. Beginning with the third day total aerobic count increased significantly explainable by the increase of pseudomonads. There were problems with minced meat produced from beef, that was of lower quality and not fresh. EC-regulations can be fulfilled and are reasonable in case of industrial production when considering the quality of the processed meat and seasonal differences. Therefore microbiological quality control is justified.

Animals↗
PubMed1994

[Suitability of sampling methods for environmental studies in meat rendering and processing plants with European Community licenses].

In EC-licensed meat rendering and processing plants microbiological test results obtained through contact slides and a highly precise swab method were compared. It was revealed that when using contact slides the absolute cfu can be determined only after prior verification with a reference method. The key provided by the manufacturer for data interpretation does not always match with results obtained by swab technique. Nevertheless, contact plates are suitable to determine the microbiological status. However, their technical deficiencies must be compensated. A simple swab method is well suited for use in meat rendering and processing plants. It is very economical due to low material costs and easy to apply by plant hygienists. The use of a seven step scale listing results up to 10(3) cfu/cm2 enables even non-experts to interpret their results reasonably.

Animals↗
PubMed1994

[Protein fingerprinting as a method for strain-specific differentiation of technologically useful Lactobacillus strains from clinical isolates].

Lactobacilli are often used in products of animal origin because of their technological properties and as protective cultures against pathogenic microorganisms, however they are supposed to be related to human infections as well. Therefore 39 strains of species that are in biotechnological usage, including the type strains, and some clinical isolates were investigated. 9 strains of L. acidophilus, 7 of L. gasseri and 23 strains of L. rhamnosus were tested. Biochemical and physiological properties were proved by classical tests. Analysis of the total soluble cytoplasmatic protein patterns was performed with diamine silver staining, a technique not previously applied to lactobacilli. Classical tests were able to confirm all strains as belonging to one of the three species. Analysis of protein patterns allowed to differentiate between strains of the same species. In case of L. acidophilus biotechnologically used strains and clinical isolates were clustered separately. L. rhamnosus formed three clusters. SDS-PAGE of proteins together with diamine silver staining seems to be helpful to detect intra-species differences. It was stated, that technologically used strains of lactobacilli could clearly be differentiated from another and also from clinical isolates.

Animals↗
PubMed1994

Evaluation of a specific immunoinhibition method for the determination of pancreatic alpha-amylase.

Ten clinical centres in Italy participated in an evaluation of a pancreas-specific alpha-amylase assay using two monoclonal antibodies. Comparisons with electrophoretic methods showed good agreement in the reference range, but systematic deviations above it. The diagnostic information of the two methods appeared substantially different if the percentage values from electrophoresis were compared with activity units from the immunoinhibition method, but became similar if the two methods were compared on the basis of activity units. Reference intervals determined for serum/plasma corresponded to those previously published, but those determined for urine differed slightly from the published values. Clinical sensitivities for the assessment of acute pancreatitis (n = 134) were found as follows. Related to the upper limit of the control group (n = 141), the pancreatic alpha-amylase, total alpha-amylase and lipase showed sensitivities of 0.94, 0.87 and 0.93, respectively. When the cut-off point was set at the three-fold upper limit of the control group, sensitivities of 0.73, 0.53 and 0.70 were found, and the specificity was 1.00 for all three methods. Based on this commonly used higher cut-off point, the determination of lipase in addition to pancreatic alpha-amylase enhanced the sensitivity in the recognition of acute pancreatitis by 8%; conversely, the determination of pancreatic alpha-amylase in addition to lipase increased the number of true positive results by 13%. The high practicability and interlaboratory transferability documented in the results of the collaborative study show that the pancreatic alpha-amylase assay is very useful for recognizing pancreatic inflammations, especially in combination with lipase.

Acute Disease↗
PubMed1994

[High caloric parenteral nutrition in patients with mouth and oropharyngeal cancers--a clinical study].

Patients with carcinomas of the oral cavity and oropharynx often show signs of malnutrition. This is caused by reduced intake in patients due to chronic alcoholism resulting in suppressed appetite and disturbed gastrointestinal functions. Also the growth of the tumor can cause painful swallowing. The effects of chronic malnutrition reduce patients tolerance regarding surgical treatment, chemotherapy and radiation. A pretherapeutic parenteral balanced nutrition should achieve an anabolic metabolism. Changes in body cell mass (bcm) as a parameter of total protein synthesis can be estimated by bioelectrical impedance analysis in order to prove the success of this management. Twenty-eight patients participated in this study, divided into three groups: group 1 = 18 male subjects and group 3 = 3 female subjects, all able to be operated upon, and group 2 = 7 male subjects, not able to be operated. High caloric nutrition in group 1 lead to a higher increase of bcm than in group 2. The review of single cases showed that in both groups one part of the patients failed increasing bcm despite nutrition. The therapeutic response was correlated to survival by means of a Kaplan-Meier analysis and a Cox-model. Survival probability could positively be correlated to an increased bcm.

Adult↗
PubMed1994

[Determination of serum pepsinogen I and II for assessment of gastroduodenal tolerance of S(+) ibuprofen].

Therapy with non-steroidal anti-inflammatory drugs often causes gastroduodenal side effects. Changes in the gastric mucosa were studied by determination of serum pepsinogen I and pepsinogen II by the means of radioimmunoassay. 41 patients with degenerative rheumatic diseases were divided into two groups, 21 patients receiving 600 mg S(+) ibuprofen daily (3 x 200mg) and 20 patients receiving 900 mg S(+) ibuprofen daily (3 x 300 mg) over a 14-day period. No significant increase occurred in mean and median values of pepsinogen I and II. Indeed, no changes in serum pepsinogen I and II were noted in 80% of the patients in the higher dosage group and in more than 90% of the lower dosage group. None of the gastroduodenal side effects frequently reported during therapy with non-steroidal anti-rheumatic drugs occurred.

Adult↗
PubMed1993

Multistep evolution of B-cell-derived tumors in humans and rodents.

At least three genetic changes are known to contribute to the genesis of Burkitt's lymphoma (BL): the Ig/myc translocation, the presence of Epstein-Barr virus (EBV) in the vast majority of the endemic and a minority of sporadic tumors, and a p53 mutation, present in approximately 60% of the BL-derived lines. Activation of c-myc by juxtaposition to Ig sequences is a universal common denominator in endemic and sporadic EBV positive and negative BLs. It acts by preventing the cell from leaving the cycling compartment and by facilitating immune escape. EBV probably acts by expanding the target cell population at risk and prolonging its life span. This, together with the malaria co-factor, would increase the risk of the translocation accident. The p53 mutation may be essential for the continued growth of the tumors where it occurs, since introduction of wild-type p53 leads to their apoptotic death.

Animals↗