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Biomedical subjects

G Klein

Publications and source records attributed to G Klein.

At least 397 records · Page 22Linked to original sources
PubMed1991

Variable expression of latent membrane protein in nasopharyngeal carcinoma can be related to methylation status of the Epstein-Barr virus BNLF-1 5'-flanking region.

Seven virus-coded proteins, the nuclear proteins EBNA-1 to EBNA-6 and the latent membrane protein (LMP), are regularly expressed in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines. In nasopharyngeal carcinoma (NPC), only EBNA-1 is regularly expressed; LMP is detected in about 65% of the tumors. In Burkitt's lymphoma tumors only EBNA-1 is expressed. We have recently shown that the methylation patterns of the EBV genome varied between these cell types. In virally transformed lymphoblastoid cell lines of normal origin, the EBV DNA is completely unmethylated. In contrast, in the Burkitt's lymphoma-derived cell line Rael and in a nude mouse-passaged NPC tumor, C15, there was an extensive methylation of CpG pairs. The methylation extended into the coding regions of the two expressed genes, EBNA-1 (in both tumor types) and LMP (in C15). Two presumptive control regions were exempted from this overall methylation: the oriP that contains both an origin of DNA replication and an EBNA-1-dependent enhancer and the 5'-flanking region of the BNLF-1 open reading frame that codes for LMP. The latter was only exempted in the LMP expressing NPC. We have now investigated the relation between expression of LMP and methylation of DNA in the 5'-flanking 1 kb region of BNLF-1, coding for LMP. LMP was methylated in 3 of 12 NPC biopsies that did not express LMP but was partially or totally unmethylated in the remaining 9 that expressed the protein. The three BNLF-1 exons were highly methylated in all the tumors. The oriP region was unmethylated in all the tumors, as in the previously studied Rael cell line and nude mouse-passaged NPC. Also, the BamHI W enhancer region involved in the expression of EBNA nuclear proteins was methylated. None of the biopsies expressed EBNA-2. Our data show that the EBV genomes are highly methylated in NPC tumors. The strong reverse correlation between the methylation of the putative control region of the LMP gene and the expression of LMP suggests that methylation has a role in the regulation of this gene.

Antigens, Viral↗
PubMed1991

Intranuclear distribution of Epstein-Barr virus-encoded nuclear antigens EBNA-1, -2, -3 and -5.

Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) express at least seven virally encoded proteins. Their functional role, and their relationships to each other and to normal nuclear constituents are virtually unknown. As the first step towards a topographical study, the intranuclear distribution of EBV-encoded nuclear antigens EBNA-1, -2, -3 and -5 (abbreviated E1, E2 etc.) was examined in EBV-transformed LCLs by immunofluorescence and digital image analysis of fluorescence patterns. E1-E3 showed a finely granular distribution. The E2 patterns were virtually identical when comparing indirect staining using an E2-specific mouse monoclonal antibody with anticomplement immunofluorescence using a human antibody, rendered monospecific to E2 by absorption. The E1/E2 patterns showed 32% overlap and the E2/E3 10% overlap in the high overlap category (66.7-100%), while the E2/E2 comparison with two reagents showed 61% overlap in this category. This suggests that E2 and E3 largely appear in different nuclear structures, whereas E1 appears to be randomly distributed with regard to E2. The E5 pattern was radically different from that of E1, E2 and E3. The anti-E5 mouse monoclonal antibody detected 4-10 huge, globular, sharply circumscribed dots, located in dispersed chromatin areas, while the distribution of E1, E2 and E3 showed no obvious relationship to chromatin distribution. The methods described here allow a more refined topographical analysis of the EBNA protein family, mostly in relation to each other, in relation to other nuclear proteins, and with respect to specialized functional domains in interphase chromatin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of transforming growth factor-beta 1 and -beta 2 on the proliferation of Burkitt lymphoma and lymphoblastoid cell lines.

We tested the effect of transforming growth factor (TGF)-beta 1 and TGF-beta 2 on the proliferation of human B cell lines. The panel was selected to give information whether (1) their origin, (2) their phenotype, (3) their Epstein-Barr virus (EBV) carrier state, influence their responsiveness. The growth of lymphoblastoid cell lines (LCL) was not inhibited by TGF-beta 1. The EBV-carrying Burkitt lymphoma (BL) lines, Daudi, Jijoye, Rael but not Raji were inhibited. Three EBV-negative BL lines and the majority of their converted sublines were sensitive. The cell lines tested expressed TGF-beta receptors and TGF-beta 1 transcripts. The proliferation of EBV-infected B cells was inhibited by TGF-beta, their sensitivity decreased, however, after 3 days. The results suggest that the activation state of the B cells is decisive for TGF-beta sensitivity and EBV influences it indirectly by changing the cell phenotype.

B-Lymphocytes↗
PubMed1991

A new variant 15; 16 translocation in mouse plasmacytoma leads to the juxtaposition of c-myc and immunoglobulin lambda.

Mouse plasmacytomas (MPCs) induced by pristane oil, or by a combination of pristane oil and Abelson virus, carry one of two chromosomal translocations. The typical 12; 15 translocation leads to the juxtaposition of c-myc and immunoglobulin heavy-chain sequences, whereas the 6; 15 translocation links the kappa light-chain locus with the pvt-1 (plasmacytoma variant translocation) locus, located at least 75kb 3' of c-myc [Cory, S., Graham, M., Webb, E., Corcoran, L. & Adams, J. (1985). EMBO J., 4, 675-681]. Unlike the human Burkitt's lymphoma-associated translocation, the lambda/myc juxtaposed variant translocation has not been found previously in MPCs. Using unconventional MPC induction systems in which the tumor precursor cell was induced to proliferate in a secondary host, we have recently identified a 15; 16 translocation in six of the derived MPCs [Wiener, F., Silva, S., Sugiyama, H., Babonits, M. & Klein, G. (1990). Genes Chromosomes Cancer, 2, 36-43]. Chromosome 16 harbors the lambda light-chain gene. To explore whether the 15; 16 translocation represents the lambda/myc juxtaposition, we have mapped the breakpoints on chromosomes 15 and 16 by pulsed-field gel electrophoresis (PFGE). The pvt-1 region was mapped to approximately 220 kb 3' of c-myc. The breakpoint on chromosome 15 in ABPC-Ch-163-10, one of the six 15; 16 translocation-carrying MPCs, was situated approximately 80 kb 3' of c-myc and 140 kb 5' of pvt-1b, the major breakpoint cluster region of the previously analysed 6; 15 variant MPCs. The breakpoint on chromosome 16 was found to cut between the V1 and C3 regions of the lambda locus. Co-migration experiments showed that the C3 and the myc gene were juxtaposed head to tail on the 15; 16 translocation chromosome. On the reciprocal product V1 was juxtaposed to pvt-1.

Animals↗
PubMed1991

[Suitability of support materials for the fixation of microfungi].

Saccharomyces cerevisiae Müller-Thurgau F and Aspergillus spec. NH, a producer of glucoamylase, were cultivated in the presence of various supporting materials (three microspherical zeolitic particles, alpha-alumina and foam corundum). The supports were microscopically tested to find out whether they are settled by microfungi or not. Whereas the yeast cells lay on the supports only loosely the hyphae of Aspergillus grew around the supports and with the exception of foam corundum enclosed them in mycelial spheres. This phenomenon may favour the separation of fungal biomass in biotechnological processes.

Aspergillus↗
PubMed1991

[Thiamine deficiency as a cause of life threatening lactic acidosis in total parenteral nutrition].

Two patients aged 37 and 44 years developed life-threatening lactic acidosis following abdominal surgery and a period of about 3 weeks of total parenteral nutrition. Septicaemia and hypoxia were excluded as possible causes. Conventional treatment including high doses of buffer agents was unsuccessful. Thiamine (vitamin B1) depletion was suspected as the cause of the metabolic acidosis, and two doses of 400 mg thiamine were given. In both patients, the lactic acidosis improved immediately, and it disappeared following the second dose of thiamine. Both patients were subsequently discharged as symptom-free. As part of the pyruvate-dehydrogenase (PDH) complex, thiamine was capable of improving the life-threatening situation.

Acid-Base Equilibrium↗
PubMed1991

The gene from the short arm of chromosome 3, at D3F15S2, frequently deleted in renal cell carcinoma, encodes acylpeptide hydrolase.

Loss or inactivation of a gene on the short arm of chromosome 3 may contribute to the genesis of renal cell carcinoma. A gene that corresponds to the most frequently lost RFLP site (D3F15S2) is expressed in a variety of human tissues, and at a particularly high level in the kidney. Its expression is markedly reduced in renal cell carcinoma. A database search showed that the gene product is closely related to or identical with acylpeptide hydrolase. The nucleotide identity between the rat acylpeptide hydrolase and the human gene at D3F15S2 is 88%, compatible with normal species differences. It is therefore likely that the human gene product is acylpeptide hydrolase. The renal cell carcinoma is then associated with a decrease of acylpeptide hydrolase activity. The gene may represent a tumor suppressor gene, whose loss contributes to the development of renal cell carcinoma. It might be speculated that it could act e.g. by affecting the activity of a small acetylated growth factor. Alternatively, its decreased expression may merely reflect the impairment of differentiation in RCC, compared to normal kidney. Loss of a linked but irrelevant gene by the 3p deletion is another possibility.

Aminopeptidases↗
PubMed1991

Mutant p53 detected in a majority of Burkitt lymphoma cell lines by monoclonal antibody PAb240.

The status of the p53 gene in lymphoblastoid cell lines (LCLs) and Burkitt lymphoma cell lines (BLs) was investigated. Southern blot analysis demonstrated that no major deletions or rearrangements had occurred in the p53 gene in any of the cell lines. The p53 protein was examined by immunoprecipitation using two monoclonal anti-p53 antibodies. PAb1801 recognizes both wild-type and mutant p53. PAb240 reacts exclusively with mutant p53. Fourteen LCLs reacted with PAb1801, but not with PAb240, suggesting that none of them expressed mutant p53. However, one LCL had mutant p53. This LCL differs from other LCLs in that it grows to higher cell densities and has a higher agarose clonability. All BLs expressed p53. Out of 15 BLs, nine (60%) carried mutant p53, as indicated by their reactivity with PAb240. Among the nine BLs with mutant p53, eight Epstein-Barr virus (EBV)-positive. Three out of the six BLs with wild-type p53 were EBV-positive. Multiple EBV-converted sublines all exhibited the same p53 status as the parental line. Our results indicate that the p53 gene is mutated in a majority of Burkitt lymphoma cell lines (BLs), and suggest that p53 mutation contributes to the malignant phenotype of these cell lines.

Antibodies, Monoclonal↗
PubMed1991

[Standardization of the carbachol inhalation provocation tests using a reservoir method].

Provocation tests with pharmacodynamic substances should preferably be conducted as dose-effect relation tests. Reservoir methods are well suited to guarantee a relatively constant intrabronchial deposition in respect of both the site of deposition (centrally, peripherally) and the deposited quantity. A commercially produced reservoir method has been available for some time now (Provocation test IR, Pari-Medanz, Starnberg). It was the aim of our study to find out which initial concentration of carbachol is necessary with this reservoir method to avoid incidents even if there is a marked hyperreactivity. Another goal was to find out the cumulative total quantity allowing differentiation between healthy subjects and asthmatic patients (cumulative total dose; maximum possible sensitivity and specificity). In 22 patients assessed to have healthy lungs according to clinical criteria and 22 subjects suffering from clinically confirmed asthma bronchiale, provocation tests were performed using increasing quantities of carbachol: Carbachol concentrations of 0.05%, 0.1%, 0.2%, 0.4% and 1.0% were nebulized to a aerosol volume of 5 litres. Whole body plethysmography was performed after each carbachol inhalation (Raw, FEV1, ITGV), so that dose-effect relations could be established. To calculate bronchial hyperreactivity, straight lines of linear regression were calculated for Raw (y = mx) (calculation of reactivity after Orehec). From this we calculated average reactivities for healthy subjects and asthmatic patients with pertaining standard deviations. We found that an initial dose of 0.05% carbachol sprayed in an aqueous solution in relation to 5 litres, was unnecessary if the patients did not suffer from any relevant obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Carbachol inhalation provocation test using a reservoir method. 4-step test for the assessment of bronchial hyperreactivity].

Inhalative bronchial provocation tests with pharmacodynamic substances, such as histamine, methacholine or carbachol are performed to confirm or exclude bronchial hyperreactivity. The provocation schemas employed so far are often very tedious, with 8 or 9 inhalation steps, or include the danger of severe or hazardous obstructions in case of 1-step or 2-step tests. A provocation test is presented that can be conducted in about 30 minutes' time comprising only 4 inhalation steps. In a separate group of 44 clinically defined healthy subjects and patients suffering from asthma bronchiale, we determined the minimal concentration and cumulative total dose of carbachol to find a non-hazardous initial concentration on the one hand and to arrive at a best possible separation of healthy subjects and asthmatics on the other. Subsequently, 20 patients suspected of bronchial hyperreactivity were provoked by inhalation, using a commercial reservoir method 1. We used carbachol provocative solutions of 0.1 and 0.5% (0.1% 5 1, 0.1% 5 1, 0.5% 5 1, 0.5% 5 1, 0.5% 10 1). At the beginning and at the end of the study, whole body plethysmography was performed (Raw, FEV1, ITGV). A peak flow meter was employed for the intermediate steps. 13 of the 20 patients showed bronchial hyperreactivity. 11 of these 13 patients were provoked according to the schema mentioned above; an intermediate step was introduced in 2 patients. The peak flow dropped on the average by 28% and the FEV1 on the average by 33%. The airway resistance increased by 300% on the average compared with the initial value. There were no severe obstructions that required parenteral treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Asthma↗
PubMed1991

[Changes in the serum pepsinogen level during therapy with acemtacin retard as a measure of gastroduodenal tolerance].

Early indications of the development of gastroduodenal lesions can be obtained with the radioimmunological determination of pepsinogen I in serum. The influence of the non-steroidal anti-inflammatory drug Acemetacin in depot form on the course of the pepsinogen levels in serum was examined during 14 day therapy. Mean and median of pepsinogen I in the whole group of 26 patients did not increase significantly. Likewise no increases of the single pepsinogen levels in serum were seen in 85%. Only 4 patients showed increases of about 20 to 27% compared with the initial values. These results indicate that Acemetacin with prolonged action is well tolerated and has only mean influence on the integrity of the mucosa.

Adult↗
PubMed1991

[Results of the multicenter evaluation of a new test for measuring beta-N-acetylglucosaminidase in urine].

We report on the results of a multicentric evaluation of a new kinetic method for the determination of beta-N-acetylglucosaminidase. Main topics of investigation were imprecision, recovery in controls with interlaboratory survey, measuring range, calibration stability, method comparisons using native urine and interferences. Distinct advantages in practicability and interlaboratory transferability compared to the introduced methods were observed. The new method fulfills the conditions to be adapted as routine method in the quantitative photometric analysis of urine.

Acetylglucosaminidase↗
PubMed1991

[A new kinetic method for measuring beta-N-acetylglucosaminidase activity in urine].

A short overview of the biochemical and technical basis for measurement of beta-N-acetylglucosaminidase (beta-NAG, EC 3.2.1.30) is given. Advantages and disadvantages of various methods are discussed and the need has to be well founded to develop a new colorimetric assay. Some technical details of a new colorimetric test for the measurement of beta-NAG in urine are described.

Acetylglucosaminidase↗