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Biomedical subjects

R Stein

Publications and source records attributed to R Stein.

At least 163 records · Page 9Linked to original sources
PubMed1995

The role of the insulin control element and RIPE3b1 activators in glucose-stimulated transcription of the insulin gene.

The most important regulator of insulin expression in islet beta-cells is glucose, which stimulates insulin gene transcription, protein synthesis, and secretion. Glucose-induced insulin gene transcription is regulated by cis-acting elements found within the 5'-flanking region of the insulin gene. We previously demonstrated that the insulin control element (ICE, -100 to -91) and RIPE3b1 (-115 to -107) elements mediated this response in the HIT T-15 beta-cell line. In this study, we examined more closely how these insulin gene control elements regulate glucose-induced transcription. RIPE3b1 element binding was shown to be induced by glucose in both mouse beta TC-6 and beta TC-3 cell lines, although higher glucose concentrations were necessary in the beta-cells (beta TC-6) that responded to physiological glucose concentrations. RIPE3b1 binding was also regulated in glucose-stimulated beta- cells by various effectors of this response. The RIPE3b1 or ICE elements were shown to independently direct glucose-stimulated expression from minimal heterologous promoter constructs. We conclude that the RIPE3b1 and ICE elements are the principal mediators of glucose-stimulated transcription of the insulin gene.

Animals↗
PubMed1995

The reduction of insulin gene transcription in HIT-T15 beta cells chronically exposed to high glucose concentration is associated with the loss of RIPE3b1 and STF-1 transcription factor expression.

The most important regulator of insulin gene expression in pancreatic beta- cells is glucose, which affects gene transcription, mRNA translation, and secretion. Insulin gene transcription is both positively and negatively regulated by glucose. Recently, we have shown that the inhibition of insulin gene transcription caused by passaging HIT T-15 beta-cells, in the presence of high glucose, was due, in part, to reduced expression of a key regulator of insulin enhancer-mediated expression, somatostatin transcription factor-1 (STF-1). In this study, we have examined whether the activity of the other essential transcription regulators of insulin gene expression, the RIPE3b1 and insulin control element (ICE) activators, were also influenced in these HIT T-15 cells. The results show that the binding and trans-activation functions of the RIPE3b1 activator are reduced in parallel with the loss in STF-1 and insulin gene expression. In contrast, the regulatory properties of the ICE activator are unaffected. Our studies indicate that insulin gene transcription is inhibited by glucose through a mechanism involving reduced expression of both the RIPE3b1 and STF-1 activators in HIT T-15 cells but is independent of the ICE activator.

Animals↗
PubMed1995

Expression of murine STF-1, a putative insulin gene transcription factor, in beta cells of pancreas, duodenal epithelium and pancreatic exocrine and endocrine progenitors during ontogeny.

The XlHbox 8 homeodomain protein of Xenopus and STF-1, its mammalian homolog, are selectively expressed by beta cells of adult mouse pancreatic islets, where they are likely to regulate insulin expression. We sought to determine whether the expression of the homeobox protein/s during mouse embryonic development was specific to beta cells or, alternatively, whether XlHbox 8/STF-1 protein/s were initially expressed by multipotential precursors and only later became restricted to the insulin-containing cells. With two antibodies, we studied the localization of STF-1 during murine pancreatic development. In embryos, as in adults, STF-1 was expressed by most beta cells, by subsets of the other islet cell types and by mucosal epithelial cells of the duodenum. In addition, most epithelial cells of the pancreatic duct and exocrine cells of the pancreas transiently contained STF-1. We conclude that in mouse, STF-1 not only labels a domain of intestinal epithelial cells but also provides a spatial and temporal marker of endodermal commitment to a pancreatic and subsequently, to an endocrine beta cell fate. We propose a model of pancreatic cell development that suggests that exocrine and endocrine (alpha, beta, delta and PP) cells arise from a common precursor pool of STF-1+ cells and that progression towards a defined monospecific non-beta cell type is correlated with loss of STF-1 expression.

Animals↗
PubMed1995

Operative reconstruction of the external and internal genitalia in female patients with bladder exstrophy or incontinent epispadias.

PURPOSE: Urologists and gynecologists rarely encounter questions on cohabitation and pregnancy in female patients with bladder exstrophy or incontinent epispadias. MATERIALS AND METHODS: Until 1994, 41 female patients underwent surgery at our institution (vaginal cutback or vaginoplasty in 23, correction of the external genitalia in 25 and uterus fixation to correct or prevent prolapse in 13). RESULTS: Followup was available in 37 patients (mean 16.8 years, with followup of 18 years or longer in 19). Of the patients 94% are satisfied with the cosmetic results. All adults engage in sexual intercourse, 4 delivered 6 children by cesarean section and 5 presently desire children. CONCLUSIONS: Fertility in patients with bladder exstrophy or incontinent epispadias is normal, and pregnancy is possible. Patients and parents should be well informed. Besides urinary tract reconstruction, correction of the external and internal genitalia should be discussed in detail.

Adolescent↗
PubMed1995

Urinary diversion in bladder exstrophy and incontinent epispadias: 25 years of experience.

PURPOSE: To determine the optimal surgical approach in achieving complete urinary continence with preservation of the upper urinary tract in the exstrophy-epispadias complex we reviewed the records of patients treated at our institution. MATERIALS AND METHODS: From 1968 to July 1994, 115 patients with bladder exstrophy/incontinent epispadias were treated of whom followup was available for 104 and 2 died of causes unrelated to urinary diversion. Mean followup is 16.7 years. In 43 of the 102 patients surgery was primarily performed at our institution (urinary diversion in 39, a modified Young-Dees procedure in 1 and sling plasty in 3). In another 59 patients urinary diversion was done secondarily after therapy elsewhere (bladder closure/bladder neck reconstruction in 34 and failed urinary diversion with incontinence in 22). Urinary diversion was performed in 49 patients, a Young-Dees procedure in 7 and genital reconstruction alone in 3. RESULTS: The present continence rates are 96% for the rectal reservoir, 97% for the Mainz pouch I and 67% for the modified Young-Dees augmentation. Upper tracts have remained stable and no bowel neoplasms have developed. CONCLUSIONS: Rectal reservoirs represent our urinary diversion of choice. After failed reconstruction/insufficient anal sphincter a Mainz pouch I is constructed and when the upper tract has deteriorated a colon conduit is created.

Bladder Exstrophy↗
PubMed1995

[PTCA-induced myocardial ischemia for detection salvaged myocardium after thrombolytic therapy of acute myocardial infarct].

In 43 patients (ages 55.8 +/- 9.0 years) with myocardial infarction treated with thrombolytic therapy presenting with one-vessel coronary artery disease, the monitoring-ECGs during PTCA (17.0 +/- 12.7 days after infarct) were analyzed. Patients with ST-segment deviations > or = 0.1 mV (group A, n = 33) were compared with those < 0.1 mV (group B, n = 10). To answer the question, if these ischemic signs might be interpreted as salvaged myocardium, parameters of infarct size were evaluated. The maximal CK-activity in group A was 867 +/- 567 IU/l, in group B 1452 +/- 992 IU/l (p < 0.05), whereas the maximal GOT-activity was 113 +/- 69 IU/l and 174 +/- 102 UI/l (p < 0.05). The number of pathologic segments of the ventriculographies in the acute phase were 9 +/- 2 and 14 +/- 3 (p < 0.05), shortly after PTCA, 12 +/- 2 and 16 +/- 2 (p = 0.06), and after 6 months, 11 +/- 4 and 13 +/- 1 (N.S.). At the same time points EDV was analyzed in both groups and revealed the following: 103 +/- 20 ml, 98 +/- 21 ml, 104 +/- 23 ml and 103 +/- 25 ml (N.S.), 101 +/- 21 ml (N.S.), 116 +/- 46 ml (N.S.).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

The role of affects in the process of change in psychotherapy.

Questioning the place of the notion of change in psychoanalytic theory and therapy, this essay tries to compare it with its homologue in change-focused theories, a comparison that shows an inverse relation between theoretical richness and an atheoretical stance oriented explicitly toward change. It is suggested that the concept of affect provides notions of flowing that are needed in structurally biased psychoanalytic theory, and that from a therapeutic point of view, an emotional relationship between the therapeutic partners endows interpretations with mutative power. Two dimensions of affects in therapy are discussed: emotional accompaniment and emotional restructuring. It is further suggested that the double-edgedness of affects accounts for the emotions "grasping" the "nucleus of change" both from the inside and from the outside, and that the process of change uses the function of emotions as motives to change something in their function as indicators and signifiers of situations.

Adult↗
PubMed1995

[The continent ileocecal pouch. The Mainz pouch I].

Since 1993 to July 1994, 374 patients underwent a Mainz Pouch procedure in their hospital. The follow up is between 4.2 +/- 2.6 years. The authors used this technique as well for bladder augmentation, bladder substitution as continent diversion. If possible, the appendix will be used for creating the continence system.

Adolescent↗
PubMed1995

[Etiology of left bundle branch block in Porto Alegre].

PURPOSE: To determine the type of cardiac disease causing left bundle branch block (LBBB) in Porto Alegre, Brazil, and to assess the role of associated left axis deviation (-30 degrees or more in the frontal plane) in order to identify a specific etiology of LBBB. METHODS: Through reports from the assistant physicians or through examination of the patients, the underlying heart disease in 264 cases of LBBB was assessed. The chi-square test was used to determine a possible association between left anterior hemiblock LBBB and one or more specific type of underlying heart disease. RESULTS: Systemic arterial hypertension (30.7%), ischemic heart disease (30.3%), valvar heart disease (8.7%), cardiomyopathies (7.5%), idiopathic degenerative disease of the conduction system (1.6%) and miscellaneous heart diseases (1.2%) were the underlying heart diseases. The presence of LBBB did not indicate any specific type of cardiac disease. CONCLUSION: The causes of LBBB in Porto Alegre are the same as reported in the international medical literature. Upward and leftward deviation (> or = -30 degrees) of QRS axis in the frontal plane did not show statistical significant association with any type of underlying cardiac disease.

Brazil↗
PubMed1994

Inhibitors of the proteasome block the degradation of most cell proteins and the generation of peptides presented on MHC class I molecules.

Reagents that inhibit the ubiquitin-proteasome proteolytic pathway in cells have not been available. Peptide aldehydes that inhibit major peptidase activities of the 20S and 26S proteasomes are shown to reduce the degradation of protein and ubiquitinated protein substrates by 26S particles. Unlike inhibitors of lysosomal proteolysis, these compounds inhibit the degradation of not only abnormal and short-lived polypeptides but also long-lived proteins in intact cells. We used these agents to test the importance of the proteasome in antigen presentation. When ovalbumin is introduced into the cytosol of lymphoblasts, these inhibitors block the presentation on MHC class I molecules of an ovalbumin-derived peptide by preventing its proteolytic generation. By preventing peptide production from cell proteins, these inhibitors block the assembly of class I molecules. Therefore, the proteasome catalyzes the degradation of the vast majority of cell proteins and generates most peptides presented on MHC class I molecules.

Amino Acid Sequence↗
PubMed1994

Comparative biodistribution and radioimmunotherapy of monoclonal antibody RS7 and its F(ab')2 in nude mice bearing human tumor xenografts.

BACKGROUND: RS7 is a murine monoclonal antibody immunoglobulin G1 with pan-carcinoma reactivity, which was raised against human squamous cell carcinoma of the lung. To optimize the use of monoclonal antibody RS7 as a carrier of radionuclides for tumor targeting and therapeutic applications, whole RS7 immunoglobulin G and its F(ab')2 fragment were radiolabeled, and their biodistribution and effectiveness as radioimmunotherapeutic agents in nude mice bearing established human tumor xenografts were evaluated. The contributions of the tumor model, monoclonal antibody form (fragment vs. intact), radioisotope (131I, 111In, 90Y, and 188Re), and antigen target were evaluated. METHODS: Cumulative absorbed radiation doses were calculated from biodistribution data, and doses were normalized to blood to estimate expected relative toxicities. Two tumor models expressing different levels of RS7-antigen were studied: ME180, a cervical carcinoma cell line, and Calu-3, an adenocarcinoma of the lung cell line. In addition, the therapeutic effectiveness of 131I-RS7-F(ab')2 was compared to that of 131I-RS7-IgG. RESULTS AND CONCLUSIONS: Doses delivered to tumor (normalized to blood) calculated for 131I-RS7-F(ab')2 and 90Y-RS7-IgG were 4.7 times and 1.8 times greater, respectively, than 131I-RS7-IgG, and therefore would be expected to yield greater therapeutic efficacy when equitoxic doses are administered. This expectation was confirmed in the radioimmunotherapy study with 131I-RS7-F(ab')2. At equivalent absorbed dose to tumor, 131I-RS7-F(ab')2 was found to effect a slightly longer suppression of tumor growth than the intact 131I-RS7 IgG, and a 50% dose escalation yielded tumor regression for a prolonged period with the fragment, whereas a similar 50% dose escalation with 131I-RS7-IgG could not be tolerated.

Adenocarcinoma↗
PubMed1994

Analysis of an insulin gene transcription control element. Positive and negative regulation appears to be mediated by different element sequences.

Pancreatic beta-cell-type-specific transcription of the insulin gene is controlled by cis-acting sequence elements lying within its enhancer region. An essential element required for expression is the insulin control element (ICE). The activity of this element is regulated by both positive- and negative-acting transcription factors. In this study, we have identified the nucleotide sequences within the ICE that are required for repression in noninsulin producing cells. Our results indicate that the cis-acting sequences involved in negative control are distinct from those required in activating expression in beta cells.

Animals↗
PubMed1994

Expression of the trans-active factors that stimulate insulin control element-mediated activity appear to precede insulin gene transcription.

Cell type-specific expression of the major differentiated products of alpha (glucagon) and beta (insulin) cells are regulated by sequences found within their 5'-flanking region. Specific transcription of the insulin gene appears to be principally controlled by a single cis-acting DNA element, termed the insulin control element (ICE). The ICE activator acts in combination with other positive regulatory factors that interact within this region to generate the correct, cell type-specific expression. In the present study, we show that the ICE activator is not only present but is functionally active in the islet glucagon-producing alpha cell line, alpha TC6. Analysis of the expression of various transfected insulin enhancer expression plasmids demonstrated that the insulin enhancer is active in alpha TC6 cells, although at a lower level than in beta cells. The reduced transcription from these constructs appears to be a consequence of the lack of other essential positive regulator(s). The alpha TC6 cells were also shown to display neuronal-like properties. Since islet cells appear to evolve from an alpha-like precursor cell that transiently expresses neuronal cell markers, these results would indicate that the ICE activator factor is induced before transcription of the insulin gene in the developing islet.

Animals↗
PubMed1994

Composition of Gomori-positive inclusions in astrocytes of the hypothalamic arcuate nucleus.

BACKGROUND: Astrocytes within the hypothalamic arcuate nucleus contain Gomori-positive inclusions that exhibit a nonenzymatic peroxidase activity. The source and composition of these Gomori-positive inclusions are currently unknown. Recent evidence, derived from cultured astrocytes, suggests that Gomori-positive inclusions may consist of autophagocytized accumulations of altered mitochondria and that the peroxidase activity is generated by iron or other metals which accumulate in these mitochondria. METHODS: The present study applies electron microscopy, energy dispersive X-ray microanalysis, and immunocytochemistry in conjunction with confocal microscopy to determine the structure and composition of Gomori-positive inclusions in vivo. RESULTS: The results indicate that Gomori-positive inclusions are heterogeneous structures often associated with microtubules and that they contain conspicuous mitochondrial components. Gomori-positive inclusions exhibit X-ray emission peaks for copper and, less often, chromium, either of which could account for the peroxidase activity. CONCLUSIONS: These results support the hypothesis that Gomori-positive inclusions are autophagosomes in which mitochondria are prominent.

Animals↗
PubMed1994

SCLC-cluster-2 antibodies detect the pancarcinoma/epithelial glycoprotein EGP-2.

Analysis of the antibodies submitted to the 3 International Workshops on Small Cell Lung Cancer Antigens has resulted in the identification of 15 clusters of antibody reactivity. One of these clusters, named SCLC cluster 2, is characterized by reactivity against an epithelium-associated 38 kDa membrane glycoprotein. SCLC cluster 2, and a number of other antibodies with reportedly similar reactivities, were shown to recognize a protein encoded by the GA733-2 gene, whereas the newly defined SCLC cluster 13 antibodies react with the GA733-1 gene product. We propose to call the antigen detected by SCLC-cluster-2 antibodies "epithelial glycoprotein 2" (EGP-2), and the epithelium-associated glycoprotein recognized by antibodies clustered in SCLC cluster 13 (see elsewhere in this volume) "epithelial glycoprotein 1" (EGP-1). A short overview of the characteristics of both proteins and the applications of anti-EGP-2 antibodies is presented.

Animals↗
PubMed1994

Characterization of cluster 13: the epithelial/carcinoma antigen recognized by MAb RS7.

Cluster 13 was defined by 2 independently derived murine monoclonal antibodies (MAbs), RS7 (IgG1) and MR54 (IgG2a), which were raised against human squamous-cell carcinoma of the lung and a human ovarian-carcinoma cell line, respectively. Immunologic and biochemical evidence demonstrated that RS7 and MR54, as well as 2 additional MAbs, MR6 (IgG2a) and MR23 (IgG1), generated in the same fusion as MR54, recognize the same antigen, a 46- to 48-kDa glycoprotein. Evaluation of the expression of antigen on the surface of tumor cell lines, Western blotting analyses, competitive binding studies, and double-determinant ELISA assays, support this conclusion. Two distinct epitopes are defined by these MAbs. In order to further characterize this antigen, amino-acid-sequence analyses were performed on peptides derived from antigen purified by affinity chromatography with MAb RS7. The sequence data obtained from 2 peptides, which were independently generated by CNBr cleavage and trypsin digestion respectively indicated identity to GA733-1. The GA733-1 genomic DNA sequence predicted a type-1 membrane protein of 35 kDa, with 4 potential N-linked glycosylation sites. The GA733-1 protein product has not been identified previously, and MAbs to this tumor-associated antigen were not previously known.

Amino Acid Sequence↗