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G Klein

Publications and source records attributed to G Klein.

At least 487 records · Page 27Linked to original sources
PubMed1989

Epstein-Barr virus-transformed pro-B cells are prone to illegitimate recombination between the switch region of the mu chain gene and other chromosomes.

Six independently maintained sublines of FLEB 14, a fetal-liver-derived Epstein-Barr virus-transformed pro-B cell line that has not yet rearranged its immunoglobulin genes, were examined after in vitro propagation during 19-36 months. Two lines showed no immunoglobulin heavy chain gene rearrangement, whereas one allele was rearranged with breakpoints inside the switch region of the mu chain gene in the remaining four. These rearrangements had been generated by the translocation of different chromosome fragments to the immunoglobulin heavy chain gene cluster-carrying 14q32 band in each of the four lines. Previously, a similar rearrangement was found in a fifth subline concurrently with a reciprocal 6;14 translocation. The transposed pieces have been derived from chromosomes 16 and 18 in two of the more recently rearranged lines. Their origins could not be determined in the remaining two lines, but they were different from each other and the other three 14q+ markers. The 14q+ marker-carrying variant has replaced its diploid progenitor suggesting that the translocation has conveyed some in vitro growth advantage on its carrier. This was also supported by the duplication of the 14q+ marker and the loss of its normal chromosome 14 homologue in one subline during serial culturing. The vulnerability of the switch region of the mu chain gene to illegitimate recombination at the pro-B stage and the possible relevance of this finding for the origin of the Burkitt lymphoma-associated 8;14 (immunoglobulin heavy chain gene cluster/MYC) translocation is discussed.

B-Lymphocytes↗
PubMed1989

The role of methylation in the phenotype-dependent modulation of Epstein-Barr nuclear antigen 2 and latent membrane protein genes in cells latently infected with Epstein-Barr virus.

Seven virus-encoded proteins are regularly expressed in Epstein-Barr virus (EBV)-transformed lymphoblastoid (LCL) cell lines: the EBV nuclear antigens EBNA 1 to 6 and the latent membrane protein (LMP). In nasopharyngeal carcinoma (NPC), only EBNA 1 is regularly expressed; LMP is detected in about 50% of the tumours. In Burkitt's lymphoma (BL) tumours, only EBNA 1 is expressed. Also, in BL-derived cell lines that maintain the phenotypic markers characteristic of the in vivo tumour (group I), only EBNA 1 is expressed. EBV was rescued by induction or cocultivation from one BL cell line with a restricted group I pattern, and from one NPC tumour, into normal B cells. In the resulting LCLs EBNA 1 to 6 and LMP were expressed. We assessed the level of methylation in the genes encoding ENBNA 2 and LMP by restriction fragment analysis using the methylation-sensitive enzymes SmaI and HpaII. These genes were extensively methylated in the group I BL line Rael and the nude mouse-passaged C15 NPC tumour, but were demethylated in the derived LCLs. In the LMP-expressing NPC C15 tumour the 5' flanking region of the gene was hypomethylated, whereas the coding exons were methylated [corrected]. The EBNA 1 coding exon was methylated in the Rael line and in NPC, in spite of expression. In contrast, CpG pairs in oriP were originally hypomethylated and remained so after their transfer to LCLs. The cell phenotype-dependent pattern of EBV gene methylation correlated with the phenotype-dependent pattern of EBNA and LMP expression. The specific patterns of methylation localized to controlling regions (oriP and 5' flanking sequences) also suggest a specific role for methylation in the regulation of EBNA and LMP expression.

Antigens, Viral↗
PubMed1989

Oncogene amplification in squamous cell carcinoma of the oral cavity.

We have determined the prevalence of amplification of c-myc, N-myc, L-myc, H-ras, Ki-ras, and N-ras oncogenes in 23 cases of squamous cell carcinoma of the oral cavity, using Southern hybridization analysis of DNA extracted from the primary tumor tissues. Nick-translated oncogene probes and oncogene inserts labeled to high specific activities were used. We observed a 5- to 10-fold amplification of one or more of c-myc, N-myc, Ki-ras and N-ras oncogenes in 56% of the tumor tissue samples, with these oncogenes not being amplified in the peripheral blood cells of the same patients. L-myc and H-ras were not amplified in any of our samples. The oncogene amplifications seemed to be associated with advanced stages of squamous cell carcinomas, with the ras and myc family oncogenes being amplified in stages 3 and 4. Hybridization with N-myc detected an additional 2.3 kb EcoRI fragment, along with the normal 2.1 kb fragment. Our data also demonstrated amplification of multiple oncogenes in the same tumor tissue sample. About 60% of the samples with amplified oncogenes showed simultaneous amplification of 2 or more oncogenes. The results showing different oncogene amplifications in similar tumors, as well as multiple oncogene amplifications in the same tumor, suggest that these oncogenes may be alternatively or simultaneously activated in oral carcinogenesis.

Adult↗
PubMed1989

Host cell-dependent regulation of growth transformation-associated Epstein-Barr virus antigens in somatic cell hybrids.

We have analyzed the expression of the three major known growth transformation-associated Epstein-Barr virus (EBV) proteins, EBNA-1, EBNA-2, and latent membrane protein (LMP), in a series of somatic cell hybrids derived from the fusion of EBV-carrying Burkitt lymphoma (BL) lines with EBV-positive or EBV-negative B-cell lines. Independently of the cell phenotype, EBNA-1 was invariably coexpressed in all EBV-carrying hybrids. In hybrids between EBV-carrying, LMP-positive and LMP-negative Burkitt lymphoma lines, LMP was expressed, indicating positive control. Two EBV-negative lymphoma lines, Ramos and BJAB, differed in their ability to express LMP after B95-8 virus-induced conversion and after hybridization with Raji cells. BJAB was permissive while Ramos was nonpermissive for LMP, although both expressed EBNA-2. The EBNA-2-deleted P3HR-1 virus gave the same pattern of LMP expression in these two cells. Our findings indicate that the expression of EBNA-1, EBNA-2, and LMP is regulated by independent mechanisms.

Antigens, Viral↗
PubMed1989

5-Azacytidine up regulates the expression of Epstein-Barr virus nuclear antigen 2 (EBNA-2) through EBNA-6 and latent membrane protein in the Burkitt's lymphoma line rael.

Nonproductive infection of B lymphocytes by Epstein-Barr virus (EBV) is associated with a highly restricted expression of viral genes. In growth-transformed lymphoblastoid cell lines, the products of these genes include a complex of at least six EBV nuclear antigens (EBNAs) (EBNA-1 through EBNA-6) and one membrane protein (latent membrane protein [LMP]). EBV-carrying Burkitt's lymphoma (BL) biopsies and derived cell lines that have retained a representative phenotype (group I BL lines) express only EBNA-1 (M. Rowe, D. T. Rowe, C. D. Gregory, L. S. Young, P. J. Farrell, H. Rupani, and A. B. Rickinson, EMBO J. 6:2743-2751, 1987). We have found that EBNA-2 through EBNA-6 and LMP can be up regulated by treating the group I BL line Rael with the DNA-demethylating agent 5-azacytidine (5-AzaC). The drug acted in a time- and dose-dependent manner. EBNA-2-positive cells were detected by anti-complement immunofluorescence staining just 12 h after addition of 4 microM 5-AzaC and reached a maximum number at 72 h, when up to 75% of the population was positive. EBNA-2, EBNA-3, EBNA-4, EBNA-4, EBNA-6, and LMP were demonstrated immunoblots starting at 48 h. The EBV-encoded early antigens and viral capsid antigens were also induced but at a lower level. EBNA-2 and the lytic cycle-associated antigens appeared with a different time course and in largely nonoverlapping cell subpopulations, as demonstrated by double fluorescence staining. Thus, EBNA-2 expression was not restricted to lytically infected cells, nor was EBNA-2 required for entry into the lytic cycle. The coding and regulatory sequences of EBNA-2 and LMP were found to be highly methylated in Rael cells and were, as expected, demethylated after 5-AzaC treatment. These findings suggest that DNA methylation may participate in the regulation of growth transformation-associated viral genes in BL cells.

Antigens, Viral↗
PubMed1989

Reference ranges for alpha-amylase in serum and urine with 4,6-ethylidene-(G7)-1-4-nitrophenyl-(G1)-alpha,D-maltoheptaoside as substrate.

Reference ranges for alpha-amylase in serum, spontaneously voided urine, and 24 h urine were determined, using 4,6-ethylidene-(G7)-1-4-nitrophenyl-(Gl)-alpha,D-maltoheptaoside as the substrate (EPS method), at 25, 30, and 37 degrees C. The measured values were evaluated with and without the use of a factor which converts the results of the alpha-amylase EPS method into values comparable to those obtained with the alpha-amylase PNP method (substrate: 4-nitrophenyl-alpha,D-maltoheptaoside); comparison with the established reference ranges of the PNP method was therefore possible. The values for urine sometimes deviated markedly from the PNP reference ranges, but the values for serum showed close agreement. With the use of the conversion factor, the following reference ranges are proposed for the new alpha-amylase method: Serum (186 males and 131 females): up to 120 U/l (25 degrees C), up to 160 U/l (30 degrees C), and up to 220 U/l (37 degrees C). Spontaneously voided urine: up to 600 U/l (n = 323, 25 degrees C), up to 800 U/l (n = 373, 30 degrees C), and up to 1000 U/l (n = 373, 37 degrees C). 24 h urine: up to 450 U/24 h (n = 90, 25 degrees C), up to 650 U/24 h (n = 129, 30 degrees C), and up to 900 U/24 h (n = 129, 37 degrees C).

Adolescent↗
PubMed1989

Acute effects of intravenous UD-CG 115 BS (pimobendan) on the cardiovascular system and left ventricular pump function.

Acute hemodynamic effects of 5 and 10 mg i.v. UD-CG 115 BS (pimobendan) were studied by right and left heart catheterization in idiopathic dilated cardiomyopathy (NYHA classes II and III; 5 mg = group I, n = 6; 10 mg = group II, n = 6). Effects on left ventricular function were evaluated by left ventricular angiograms and measurement of left ventricular dp/dtmax before and 2.5 h after administration of UD-CG 115 BS. Right atrial pressure (RAP), pulmonary capillary wedge pressure (PCP), cardiac output (CO), heart rate (HR), and systemic blood pressure (BP) were assessed before and 2.5, 4, and 6 h after administration of UD-CG 115 BS. PCP was maximally reduced by 10 mg of UD-CG 115 BS from 18.3 +/- 6.2 to 6.2 +/- 3.4 mm Hg (p less than 0.005) and by 5 mg from 12.2 +/- 7.5 to 8.3 +/- 7.1 mm Hg (p less than 0.05). Maximum reduction of RAP was significant only in group II (p less than 0.05). CO increased in a similar way after both doses (group I: from 5.5 +/- 1.9 to 7.8 +/- 1.3 L/min, p less than 0.005; group II: from 5.0 +/- 1.3 to 7.5 +/- 1.8 L/min, p less than 0.05). Mean arterial blood pressure was slightly reduced only by 10 mg of UD-CG 115 BS. Heart rate rose from 84 +/- 11 to 100 +/- 14 beats/min in group I (p less than 0.05), whereas after 10 mg no change in heart rate was noted. Left ventricular end-diastolic (EDVI) and end-systolic volume (ESVI) indices were clearly reduced by both 5 and 10 mg of UD-CG 115 BS.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomyopathy, Dilated↗
PubMed1989

[Molecular analysis of mouse major histocompatibility complex class I gene expression of tumors growing in the brain].

The authors have investigated the regulation of mouse major histocompatibility complex (MHC, H-2) class I gene expression of tumors growing in the brain, by using T-cell lymphoma (Moloney leukemia virus-induced YAC-1 of A/Sn mouse origin) and its cell surface H-2 negative variants, A. H-2- and beta 2m-. FACS analysis showed that low H-2 expressing YAC-1 markedly increased H-2 Kk, Dd and beta-2 microglobulin (beta 2m) induction on the cell surface after intracerebral (i.c.) passage, while there was no change in phenotypical expression of both A. H-2- and beta 2m-. Southern and Northern blot analyses revealed that the enhancement of H-2 class I expression in YAC-1 was due to transcriptional control of H-2 DNA genes. beta 2m- was confirmed to lack beta 2m- gene, causing cell surface H-2 negative expression. Immunoprecipitation method showed that, despite increase in mRNA of the H-2 gene, A. H-2- disclosed no class I H-2 expression because of the incapability of intracellular association of polypeptides between H-2 and beta 2m in the post-translational level. The H-2 class I expression on YAC-1 cells could also be induced by interferon gamma (IFN) in a dose-dependent manner in the range of 1 to 100 U/ml. At 100 U/ml, the H-2 inducing effect, regulated at the transcriptional level, was comparable to that observed after i.c. passage. In contrast, the A. H-2- and beta 2m- remained completely negative after IFN treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Reversion of tumorigenicity in an EBV-converted Burkitt's lymphoma line.

One of five Epstein-Barr virus (EBV)-converted sublines of an EBV-negative Burkitt's lymphoma line (BL-41) was identified as a non-tumorigenic phenotypic revertant with low clonability, comparable to that of an EBV-transformed lymphoblastoid cell line (IARC-171) derived from the same patient. This revertant subline (BL-41/95) also showed the most LCL-like phenotype of the five convertants tested. It is suggested that reversion was due to the phenotypic shift of the cell from a 'window' of cell ontogeny that contains virgin B cells and memory B cells to the stage of the activated immunoblast. Constitutive activation of the c-myc gene by translocation to an immunoglobulin locus continues to drive proliferation of B cells in vivo even after they have undergone a programmed switch to a basically resting (virgin or memory cell) phenotype. An activated immunoblast invariably expresses c-myc. It is also suggested that proliferation of the activated immunoblast is regulated by negative host controls that prevent clonal overexpansion and keep the B cell pool constant. The sensitivity of the immunoblast to this control overrides the 'forward-driving' force of both EBV and the activated myc gene.

Biomarkers, Tumor↗
PubMed1989

Forward and reverse changes in Ig/myc translocation carrying tumors.

Translocation of the c-myc protooncogene to an immunoglobulin locus is a rate-limiting step in the genesis of three B cell derived tumors: Burkitt lymphoma (BL) in humans, mouse plasmacytoma (MPC), and rat immunocytoma (RIC). The translocation appears as a rate-limiting step in the genesis of all three tumors. Its consequences have been best analyzed in BL. They involve a non-immunological and an immunological component. The former acts by preventing the B cell from leaving the cycling compartment and entering the resting stage when programmed to do so. The latter acts by the down-regulation of certain human leucocyte antigen (HLA) class I polymorphic specificities, adhesion molecules and Epstein-Barr virus (EBV) encoded proteins. Together, they contribute to the escape of the BL cell from the host immune response. We have also described a non-clonogenic, non-tumorigenic "revertant", subline among five EBV-convertants of an originally highly tumorigenic, EBV-negative BL line. The other four convertants have remained highly tumorigenic. Suppression of tumorigenicity is associated with a switch to a lymphoblastoid line (LCL)-like phenotype, accompanied by the appearance of several activation markers. It is suggested that the LCL-type immunoblast comes under the influence of host feedback that normally contribute to the constancy of the B cell pool.

Animals↗
PubMed1989

[Experimental analysis of intracerebral natural resistance against H-2+ and H-2- lymphomas grafted into the brain].

The authors have investigated intracerebral natural resistance mechanism after tumor transplantation into the brain, by using YAC-1 (Moloney leukemia virus-induced T cell lymphoma of A/Sn mouse origin) and its H-2 negative A. H-2-. It was found that highly immunogenic H-2+ YAC-1 was less tumorigenic than A. H-2- in untreated as well as NK-depleted syngeneic mice. The variant cells were not rejected even if inoculated together with YAC-1 cells into the brain. Furthermore, in T cell-depleted, thymectomized mice YAC-1 was as tumorigenic as A. H-2-. Thus, intracerebral natural resistance was expressed against YAC-1, suggesting that T cells but not NK cells might be involved in the tumor rejection with an MHC-restricted regulation. Contrary to this, A. H-2- cells escaped from the natural resistance of the brain. In vitro cytotoxicity assays showed that in relation to the enhancement of cell surface H-2 antigens, intracerebrally passaged YAC-1 cells decreased and increased the sensitivity to NK- and CTL-mediated lysis, respectively. In contrast, A. H-2- did not alter either susceptibility to cell-mediated lysis or cell surface H-2 expression. In vivo rapid elimination assays revealed that after intravenous or subcutaneous inoculation there was a more efficient abrogation of 125I-iododeoxyuridine (IUdR) labelled YAC-1 cells in normal untreated mice compared to NK-depleted mice. After intracerebral inoculation, however, no difference in remaining radioactivity was observed between untreated and NK-depleted mice. This indicates that selective NK-mediated elimination of tumor cells might occur after intravenous or subcutaneous but not after intracerebral inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Acute and chronic effects of UDCG 115 BS (pimobendan) in patients with advanced myocardial failure].

In a double-blind, placebo-controlled cross-over study acute hemodynamic effects of oral UDCG 115 BS (5 and 10 mg) were investigated in myocardial heart failure before (n = 16) and after (n = 13) chronic treatment (4 weeks). Before chronic treatment, UDCG 115 BS induced a similar increase in cardiac index with both doses (5 mg: from 2.4 +/- 0.7 to 3.5 +/- 0.7 l/min/m2, p less than 0.001; 10 mg: from 2.5 +/- 0.6 to 3.6 +/- 0.9 l/min/m2, p less than 0.001). Both right atrial pressure and pulmonary capillary wedge pressure were clearly reduced (p less than 0.001). Heart rate increased slightly only after 5 mg (p less than 0.05). Systemic vascular resistance was reduced (p less than 0.001), whereas mean blood pressure did not change. After chronic treatment (2 x 5 or 2 x 10 mg/d) and cessation of medication for 24 h there was no difference for control hemodynamic values as compared to placebo. Acute hemodynamic effects were considerably attenuated in comparison with the results obtained before chronic treatment. NYHA-classification, however, clearly (p less than 0.05) improved during administration of UDCG 115 BS as compared to placebo. Two patients died on placebo, whereas no patient expired on verum. This might indicate a therapeutic longterm effect of UDCG 115 BS, despite the observed development of partial tolerance.

Adult↗