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Biomedical subjects

R Ehrlich

Publications and source records attributed to R Ehrlich.

At least 19 recordsLinked to original sources
PubMed1995

Functional domain analysis of interferon consensus sequence binding protein (ICSBP) and its association with interferon regulatory factors.

Interferon consensus sequence binding protein (ICSBP) is a member of the interferon regulatory factor (IRF) family of proteins that include IRF-1, IRF-2, and ISGF3gamma which share sequence similarity at the putative DNA binding domain (DBD). ICSBP is expressed exclusively in cells of the immune system and acts as a repressor of interferon consensus sequence (ICS) containing promoters that can be alleviated by interferons. In this communication, we have searched for functional domains of ICSBP by dissecting the DBD from the repression activity. The putative DBD of ICSBP (amino acids 1-121) when fused in frame to the transcriptional activation domain of the herpes simplex VP16 (ICSBP-VP16) is a very strong activator of ICS-containing promoters. In addition, ICSBP-VP16 fusion construct transfected into adenovirus (Ad) 12 transformed cells enabled cell surface expression of major histocompatibility complex class I antigens as did treatment with interferon. On the other hand, the DBD of the yeast transcriptional activator GAL4 was fused in frame to a truncated ICSBP in which the DBD was impaired resulting in a chimeric construct GAL4-ICSBP. This construct is capable of repressing promoters containing GAL4 binding sites. Thus, ICSBP contains at least two independent domains: a DBD and a transcriptional repressor domain. Furthermore, we have tested possible interactions between ICSBP and IRFs. The chimeric construct GAL4-ICSBP inhibited the stimulated effect of IRF-1 on a reporter gene, implying for a possible interaction between IRF-1 and ICSBP. Electromobility shift assays, demonstrated that ICSBP can associate with IRF-2 or IRF-1 in vitro as well as in vivo. Thus, ICSBP contains a third functional domain that enables the association with IRFs. These associations are probably important for the fine balance between positive and negative regulators involved in the interferon-mediated signal transduction pathways in cells of the immune system.

Base Sequence↗
PubMed1995

Characterization of mature and immature RadLV-induced thymic T-cell lines for tumorigenesis and MHC-class-I gene expression.

Class-I-MHC molecules are divided into class-Ia molecules, which play major roles in recognition of virus-infected cells, graft rejection and immune responses against tumors, and class-Ib molecules, which are less polymorphic and may be responsible for presenting unique classes of peptides. Our report characterizes RadLV-induced thymic T-cell lines that differ both in their tumorigenic potential and in the level of protein for class-Ia and TL genes. The PD1.1 cell line is CD4-CD8+ and expresses relatively high levels of class-I as compared with the CD4+CD8+ PD1.2 cell line. These class-I-expression levels correlate with thymocytes and splenic T cells of the same phenotype, except that normal cells fail to express TL3b. Interferon-treated PD1.2 cells demonstrate significantly lower levels of class-I expression than do interferon-treated PD1.1 cells, and were shown to contain large amounts of degraded class-I mRNA, at least some of which was TL in origin. These RNA products were not detected in PD1.1 cells, suggesting the existence of a mechanism controlling cell-specific and gene-specific mRNA stability. Such RadLV-induced cell lines provide a means for obtaining stage-specific T cells, which can be used for studying the regulation of class-I gene expression during T-cell differentiation, as well as factors that differentially regulate class-Ia and class-Ib expression and are potentially useful for studying T-cell differentiation in general.

Animals↗
PubMed1995

Complications of laparoscopic nephrectomy in 185 patients: a multi-institutional review.

PURPOSE: We document the incidence of complications associated with laparoscopic nephrectomy in a multi-institutional study. MATERIALS AND METHODS: The study included the initial 185 patients undergoing laparoscopic nephrectomy at 5 centers in the United States between June 1990 and July 1993. RESULTS: A total of 30 patients (16%) had 34 complications. There was no mortality. Access-related complications included 2 cases of hernia formation at the trocar site, 1 abdominal wall hematoma and 1 trocar injury to a hydronephrotic kidney. Intraoperative complications included 5 cases of vascular injury, 1 splenic laceration and 1 pneumothorax. Postoperative complications involved the gastrointestinal tract in 6 cases, cardiovascular system in 6, genitourinary tract in 4, respiratory system in 4 and musculoskeletal system in 2. Miscellaneous complications occurred in 3 patients. Open surgical intervention was required electively in 8 patients and on an emergency basis in 2. The incidence of complications decreased with experience: 71% occurred during the initial 20 cases at each institution. CONCLUSIONS: In our early experience the complication rate for laparoscopic nephrectomy was 12% in patients with benign renal disease and 34% in those with renal cancer. Based on this collective experience, recommendations for prevention, recognition and treatment of complications are made.

Adult↗
PubMed1994

Downregulation of peptide transporter genes in cell lines transformed with the highly oncogenic adenovirus 12.

The expression of class I major histocompatibility complex antigens on the surface of cells transformed by adenovirus 12 (Ad12) is generally very low, and correlates with the high oncogenicity of this virus. In primary embryonal fibroblasts from transgenic mice that express both endogenous H-2 genes and a miniature swine class I gene (PD1), Ad12-mediated transformation results in suppression of cell surface expression of all class I antigens. Although class I mRNA levels of PD1 and H-2Db are similar to those in nonvirally transformed cells, recognition of newly synthesized class I molecules by a panel of monoclonal antibodies is impaired, presumably as a result of inefficient assembly and transport of the class I molecules. Class I expression can be partially induced by culturing cells at 26 degrees C, or by coculture of cells with class I binding peptides at 37 degrees C. Analysis of steady state mRNA levels of the TAP1 and TAP2 transporter genes for Ad12-transformed cell lines revealed that they both are significantly reduced, TAP2 by about 100-fold and TAP1 by 5-10-fold. Reconstitution of PD1 and H-2Db, but not H-2Kb, expression is achieved in an Ad12-transformed cell line by stable transfection with a TAP2, but not a TAP1, expression construct. From these data it may be concluded that suppressed expression of peptide transporter genes, especially TAP2, in Ad12-transformed cells inhibits cell surface expression of class I molecules. The failure to fully reconstitute H-2Db and H-2Kb expression indicates that additional factors are involved in controlling class I gene expression in Ad12-transformed cells. Nevertheless, these results suggest that suppression of peptide transporter genes might be an important mechanism whereby virus-transformed cells escape immune recognition in vivo.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

De novo methylation of an MHC class I transgene following transformation with human adenoviruses is not correlated with its altered expression.

The biological importance of class I histocompatibility antigens in a large variety of immune mechanisms is widely recognized, and their role in tumor rejection has been proven in several experimental tumor systems. Reduced expression of class I antigens, which is correlated with enhanced tumorigenicity, was shown in these systems to be mainly the result of transcriptional down-regulation. Mouse embryonal fibroblasts expressing H-2 antigens and the product of a miniature swine class I transgene, transformed by adenovirus 12, exhibit low levels of all class I antigens on the cell surface. Half of the cell lines demonstrate a suppressed level of class I mRNAs. Cell lines derived from transformation with the early region of adenovirus 5 express a high level of class I antigens. DNAs from adenovirus-transformed cells are extensively hypermethylated both in the 5' and the coding regions of the transgene compared to DNAs from immortalized cell lines and primary embryonal fibroblasts. Nevertheless, hypermethylation of these sequences is not correlated with mRNA level or cell-surface expression of the transgene product. Treatment of the transformed cells with high concentration of 5-azacytidine (5 Aza-C) induced merely a minor enhancement in the expression of class I mRNAs and class I antigens. Thus, this system is a perfect example of where viral transformation is associated with induced methylation of a class I gene, but hypermethylation does not affect its expression. The role of de novo methylation of genes in this system might be associated with transformation, or generation of mutations in CpG-rich sequences.

Adenoviridae↗
PubMed1992

Homeoboxes in flatworms.

A search for homeobox-containing genes was done in the genome of a primitive metazoan, the parasitic tapeworm Echinococcus granulosus. Five different homeoboxes were isolated, none of them belonging to the classical Antennapedia-type. Three of the homeodomains are similar to those from the Drosophila melanogaster NK-type genes. The fourth homeodomain shares extensive identity with that of the recently reported homeobox-containing gene goosecoid from Xenopus laevis. The third helix (the recognition helix) of the fifth isolated homeodomain is identical to that of the Xlim-1 gene of X. laevis and the lin11 gene of Caenorharbditis elegans. Using PCR, some Antennapedia-type homeoboxes were cloned from the genome of two other Platyhelminthes, Dugesia tigrina (planaria) and Fasciola hepatica. These data suggest that, contrary to what is found for the majority of the more complex metazoans, Platyhelminthes contain few homeobox genes belonging to the Antennapedia-type.

Amino Acid Sequence↗
PubMed1992

Long term radiological effects of short term exposure to amosite asbestos among factory workers.

Chest radiographs were read from a sub-cohort of 386 factory workers with short term exposure to amosite asbestos (median exposure six months) and long follow up (median 25 years). Prevalence of abnormality was determined independently by two readers from the first film available after 20 years from first employment. Serial films were obtainable for 238 men (median interval from first to last film: nine years). Progression was classified with a direct progression scoring scale. Individual dust exposure estimates were derived from dust counts from two similar plants. With as little as one month or less of employment, about 20% of the films showed parenchymal abnormality and about a third showed pleural abnormality. Those in the lowest cumulative exposure stratum (less than 5 fibre-years/ml) were similarly found to have high rates of abnormality. Dose-response relations were present in the data of both readers. Smokers had higher rates of parenchymal abnormality. On multivariate analysis, cumulative exposure was the exposure variable most closely related to parenchymal abnormality, and time from first employment was the variable most closely related to pleural abnormality. Progression (including first attacks) 20 or more years after ceasing employment occurred and was more common for pleural than for parenchymal abnormality. It is concluded that with exposure to high concentrations to amosite such as existed in this factory and with follow up for at least 20 years, (1) exposure for as little as a month was sufficient to produce radiological signs of parenchymal and pleural fibrosis, (2) no cumulative exposure threshold for parenchymal and pleural fibrosis was detectable, and (3) parenchymal and pleural progression were still detectable >/= 20 years after the end of exposure.

Asbestos↗
PubMed1992

Childhood asthma and passive smoking. Urinary cotinine as a biomarker of exposure.

To assess the relationship between passive smoking and asthma, we investigated (1) whether passive smoking was more prevalent among asthmatic than control children and (2) whether exposure to tobacco smoke was higher in acute asthma than in nonacute asthma. Three groups were recruited into a case-control study: 72 acute asthmatic children from the emergency room (ER), 35 nonacute asthmatic children from the asthma clinic, and 121 control children from the ER. Both questionnaire and urinary cotinine/creatinine ratio (CCR) were used to assess passive smoking. Levels of CCR greater than or equal to 30 ng/mg were used to identify children exposed at home. Mean CCR was also computed. Acute and nonacute asthmatic children had similar prevalences of passive smoking at home. Acute cases showed a higher mean CCR than nonacute cases, but this was not significant. In comparing all asthmatic to control children, smoking by the maternal caregiver was more prevalent among asthmatic children (odds ratio OR = 2.0, 95% CI 1.1, 3.4). This was confirmed by CCR greater than or equal to 30 ng/mg (OR = 1.9, 95% CI 1.04, 3.35) and by the difference in mean CCR (43.6 versus 25.8 ng/mg, p = 0.06). We conclude that smoking by the maternal caregiver is associated with clinically significant asthma in children. We could not show that it is a trigger of acute asthma attacks.

Acute Disease↗
PubMed1991

Marfanoid children. Etiologic heterogeneity and cardiac findings.

The clinical, cardiac, and echocardiographic test results of 20 children with marfanoid features are reviewed. Fifteen were diagnosed as having Marfan syndrome, two had "possible" Marfan syndrome, and three had other diagnoses. On first evaluation, eight patients with Marfan syndrome (53%) had mitral regurgitation and none had aortic regurgitation. Echocardiography showed aortic root enlargement in 12 (80%) of 15 patients and mitral valve prolapse in 12 (80%) of 15. None had a normal echocardiogram. At follow-up examination, one patient had developed aortic root enlargement, and one patient, mitral valve prolapse. Thus, although aortic root enlargement is usually present in early childhood in patients with Marfan syndrome, it is not considered specific because in this study it also occurred in one child with Alport's syndrome and in one with marfanoid features. Four patients with aortic root enlargement were treated with propranolol and their echocardiograms showed no further increase in the aortic root diameter for several years. We recommend echocardiography in the diagnosis and routine management of children in whom Marfan syndrome is suspected.

Aortic Diseases↗
PubMed1991

High-dose 1,2,4-triglycidylurazol given in regimens preparatory to bone marrow transplantation. A preclinical pharmacology study.

To elucidate its potential role in the framework of bone marrow transplantation, we studied the toxicologic and pharmacologic properties of high doses of the triepoxide derivate 1,2,4-triglycidylurazol (TGU) in a preclinical dog model. Dose-dependent and dose-limiting gastrointestinal toxicity occurred in a dose range between 40 and 75 mg/kg, with the lethal dose for 50% of animals (LD50) being estimated at 60 mg/kg. Severe and life-threatening hematologic toxicity developed at all dose levels examined but was generally reversible. The combination of TGU and total-body irradiation produced synergistic gastrointestinal toxicity, necessitating reductions of the TGU dose by 50% as compared with the single-agent dose. In contrast, the combination of TGU and high-dose busulfan resulted in no apparent nonhematologic synergistic toxicities. The immunosuppressive properties of TGU given in this combination enabled sustained histocompatible allogeneic marrow engraftment in three of four animals. The pharmacokinetics of TGU were not influenced by prior total-body irradiation or high-dose busulfan. We conclude that the myelotoxic, pharmacologic and immunosuppressive properties of high-dose TGU observed in this preclinical model seem to render the drug particularly suitable for use in regimens preparatory to bone marrow transplantation.

Animals↗
PubMed1991

Transcriptional and posttranscriptional regulation of class I major histocompatibility complex genes following transformation with human adenoviruses.

Transformation of rodent cells by human adenoviruses is a well-established model system for studying the expression, regulation, and function of class I antigens. In this report, we demonstrate that the highly oncogenic adenovirus type 12 operates at the transcriptional and posttranscriptional levels in regulating the activity of major histocompatibility complex class I genes and products in transformed cells. Adenovirus type 12 suppresses the cell surface expression of class I antigens in most cell lines. Nevertheless, in a number of cell lines suppression is the result of reduction in the amount of stable specific mRNA, while in another group of cell lines suppression involves interference with processing of a posttranscriptional product. The two mechanisms operate both for the endogenous H-2 genes and for a miniature swine class I transgene that is expressed in the cells.

Adenoviruses, Human↗
PubMed1989

In vivo gene expression directed by synthetic promoter constructions restricted to the -10 and -35 consensus hexamers of E. coli.

Two synthetic DNA sequences, carrying no other known E. coli promoter element than the consensus hexamers (CH) TTGACA (CH-35) and TATAAT CH(-10), spaced by 17 bp, were inserted in pBR329, in a position enabling transcription of the complete Cmr gene. The region upstream of the Cmr transcription start was carefully cleared of w.t. promoter elements (full deletion of the wild type (w.t.) Cmr promoter upstream +2 and large portion of an upstream coding sequence). Both synthetic promoters, which differ only by the sequences of the spacers (non consensus, constrained in AT or GC) support in vivo high level Cmr gene expression. The GC rich spacer is associated with transcription start at the usual +1 position, but with the AT rich spacer, transcription starts at several places, mainly in CH(-10). Rearranged promoter sequences derived from the synthetic ones upon transformation with partly ligated plasmids, yield new insights on the role of the standard CH pair, the size of the spacer and the sequence downstream of CH(-10).

Base Sequence↗