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Biomedical subjects

R Bernstein

Publications and source records attributed to R Bernstein.

At least 37 records · Page 2Linked to original sources
PubMed1995

TATA-binding protein residues implicated in a functional interplay between negative cofactor NC2 (Dr1) and general factors TFIIA and TFIIB.

The TATA-binding protein (TBP) plays a key role in transcription initiation. Several negative cofactors (NC1, NC2, and Dr1) are known to interact with TBP in a manner that prevents productive interactions of transcription factors TFIIA and TFIIB with promoter-bound TBP. To gain insights into the regulatory interplay on the surface of TBP, we have employed mutant forms of TBP to identify amino acid residues important for interactions with the negative regulatory cofactor NC2 and the general factor TFIIB. The results show the involvement of distinct domains of TBP in these interactions. Residues (Lys-133, Lys-145, and Lys-151) in the basic repeat region are important for interactions with NC2, as well as with TFIIA (Buratowski, S., and Zhou, H. (1992) Science 255, 1130-1132; Lee, D. K., DeJong, J., Hashimoto, S., Horikoshi, M., and Roeder, R. G. (1992) Mol. Cell. Biol. 12, 5189-5196), whereas a residue (Leu-189) in the second stirrup-like loop spanning S2' and S3' is required for interaction with TFIIB. In addition, we demonstrate that NC2 is identical to the previously cloned negative cofactor Dr1. The implications of these results for TBP structure and function are discussed.

Binding Sites↗
PubMed1995

Human general transcription factor TFIIA: characterization of a cDNA encoding the small subunit and requirement for basal and activated transcription.

The human general transcription factor TFIIA is one of several factors involved in specific transcription by RNA polymerase II, possibly by regulating the activity of the TATA-binding subunit (TBP) of TFIID. TFIIA purified from HeLa extracts consists of 35-, 19-, and 12-kDa subunits. Here we describe the isolation of a cDNA clone (hTFIIA gamma) encoding the 12-kDa subunit. Using expression constructs derived from hTFIIA gamma and TFIIA alpha/beta (which encodes a 55-kDa precursor to the alpha and beta subunits of natural TFIIA), we have constructed a synthetic TFIIA with a polypeptide composition similar to that of natural TFIIA. The recombinant complex supports the formation of a DNA-TBP-TFIIA complex and mediates both basal and Gal4-VP16-activated transcription by RNA polymerase II in TFIIA-depleted nuclear extracts. In contrast, TFIIA has no effect on tRNA and 5S RNA transcription by RNA polymerase III in this system. We also present evidence that both the p55 and p12 recombinant subunits interact with TBP and that the basic region of TBP is critical for the TFIIA-dependent function of TBP in nuclear extracts.

Amino Acid Sequence↗
PubMed1995

Presence of Y chromosome sequences and their effect on the phenotype of six patients with Y chromosome anomalies.

The extent of Y chromosome material was determined in 6 southern African subjects with sex chromosome anomalies. Four of the subjects were phenotypically female, and 2 were phenotypically male. Molecular and cytogenetic findings were correlated with phenotypic expression. An X;Y translocation was found in both male subjects, and in one female subject. The remaining female subjects were characterized by an isodicentric Y, an isochromosome Yq, and a micromarker of undetermined origin, respectively. The individuals were tested for the presence of a number of Y-specific DNA sequences. Molecular findings were generally compatible with the cytogenetic findings, and also with the phenotypic sex of the patients. All the female subjects had Y material and all but one were negative for the sex determining region of the Y (SRY). The somatic Ullrich-Turner-like findings present in 3 of the females were attributed to either the presence of a 45,X cell line and/or a single copy of Xp. The males both showed X;Y translocations without any detectable loss of Y DNA. Although molecularly very similar, the disparate clinical findings in these 2 subjects could have been accounted for by different X inactivation patterns.

Adolescent↗
PubMed1995

Incidence of hypertrophic cardiomyopathy in hypothyroidism.

In 13 consecutive severely hypothyroid patients no sign of endocrine cardiomyopathy in the form of asymmetric septal hypertrophy (ASH) could be disclosed by M-mode and two-dimensional (2D) echocardiography on examination prior to thyroxine replacement therapy. In previous investigations ASH was demonstrated to be almost invariably present in untreated hypothyroidism irrespective of thyrotropin levels. Consequently application of positive inotropic and afterload reducing agents that may invoke deleterious effects in ASH has been considered hazardous in hypothyroidism even when indicated by concurrent other heart disease. Determination of exact confidence limits reveals that the proportional incidence of hypothyroid hypertrophic cardiomyopathy could not exceed 24.7% with 95% probability. We conclude that ASH is not necessarily inherent in hypothyroidism.

Adult↗
PubMed1995

Silent myocardial ischemia in hypothyroidism.

In some patients with severe hypothyroidism thyroxine replacement therapy precipitates or aggravates angina pectoris, whereas in other patients angina pectoris is ameliorated or even disappears. The reason for this paradox is unknown. It has been attributed either to reversible endocrine cardiomyopathy in the form of asymmetric septal hypertrophy (ASH) or reversible anatomical narrowing of the coronary arteries. The results of a recent investigation, in which myocardial performance was surveyed by radionuclide ventriculography throughout early thyroxine replacement therapy in severe hypothyroidism, were compatible with the presence of reversible coronary dysfunction rather than of ASH. The aim of the present investigation was to confirm these findings. In six severely hypothyroid patients, without echocardiographic evidence of ASH or evidence of concomitant coronary artery disease (CAD), exercise and redistribution tomographic myocardial thallium-201 imaging (SPECT) was performed before thyroxine replacement therapy and repeated after 10 days and again after 2 months during therapy. In four patients substantial regional perfusion defects were demonstrated after exercise that were normalized at rest both before, and in one subject also after 10 days, on thyroxine. With restoration of euthyroidism, exercise and redistribution SPECT were normal in every patient. Determination of exact confidence limits reveals that the proportional incidence of myocardial perfusion defects in hypothyroidism, indicating myocardial ischemia, will at least be 22% with 95% probability. Despite the relatively low specificity of SPECT it seems pertinent to conclude that impaired myocardial perfusion as assessed by SPECT probably is due to reversible coronary dysfunction inherent in the hypothyroid state, and that this is not an infrequent manifestation of severe hypothyroidism.

Adult↗
PubMed1994

Characterization of the highly conserved TFIIA small subunit from Drosophila melanogaster.

TFIIA is a general transcription factor that modulates class II transcription initiation in vitro by functionally and physically interacting with TFIID or the derived TATA-binding protein (TBP). TFIIA was previously purified from human, bovine, rat, and yeast sources and has recently been identified in association with TFIID in Drosophila. Here, we report the cloning of a cDNA encoding the 12.5-kDa subunit of TFIIA from Drosophila melanogaster (dTFIIA-S) and the identification of a partial dTFIIA-S gene in Drosophila virilis. The deduced amino acid sequence of dTFIIA-S indicates a high degree of homology to the small TFIIA subunit from yeast and to a partial TFIIA-S cDNA identified in rice. A hybrid TFIIA consisting of recombinant dTFIIA-S and the recombinant human TFIIA/alpha gene product mimics natural TFIIA activity in a TBP-dependent DNA binding assay. The promoter complex formed with this hybrid TFIIA depends upon the TATA element and can be efficiently incorporated into a higher order preinitiation complex upon addition of TFIIB. The presence of dTFIIA-S within the TBP-TFIIA-promoter complex was demonstrated using anti-dTFIIA-S antiserum. Finally, the ability of recombinant dTFIIA-S to reconstitute transcriptionally active TFIIA was demonstrated in a well defined human transcription system.

Amino Acid Sequence↗
PubMed1994

Conformations of peptide fragments comprising the complete sequence of component III of Chi t I and their relationship to T-cell stimulation.

Conformational preferences of synthetic peptides that span the complete sequence of Chironomus thummi hemoglobin (Chi t I) component III were studied by nuclear magnetic resonance (NMR) and CD spectroscopies. The peptides, 19-21 amino acids in length, were studied in water, except for the C-terminal peptide, which was investigated in DMSO-d6. NMR showed that all investigated peptides lacked uniquely folded conformations in water at 4 degrees C and pH 3.0 or at 10 degrees C and pD 6.6 in DMSO. However, some preferential helix-like conformations for the peptides corresponding to the helices of the folded protein could be seen in solution. These peptides showed characteristic interactions for conformations in both the beta- and alpha-regions of phi-psi space, based on strong C alpha H(i)-NH(i + 1) interactions, and on NH-NH, C alpha H(i)-NH-(i + 2), C alpha H(i)-NH(i + 3), and C alpha H(i)-C beta H(i + 3) interactions, respectively. Helical motifs seem not to be the most important factors in determining MHC-binding and/or T-cell recognition. However, there is a tendency that more stabilized secondary structures show higher T-cell stimulation.

Allergens↗
PubMed1994

Trisomy 11 and other nonrandom trisomies in congenital fibrosarcoma.

Chromosome studies in a 7-week-old female infant with an intraabdominal malignant fibrosarcoma showed a hyperdiploid karyotype of 50,XX, +der(6)del(6)(p23)add(6)(q11), +8, +10, +11,add(12)(p13). Trisomy 11 appears to be a nonrandom primary cytogenetic abnormality in the congenital or infantile form of this mesenchymal tumor and is also a nonrandom gain in congenital mesoblastic nephroma. A possible developmental link between these two mesenchymal tumors, mediated by a gene or genes on chromosome 11 is postulated.

Chromosomes, Human, Pair 11↗
PubMed1994

Lateralization of bands of noise as a function of combinations of interaural intensive differences, interaural temporal differences, and bandwidth.

Listeners indicated the intracranial position of bands of noise (from 50 to 400 Hz in width) for several combinations of interaural intensive differences (IID), and interaural temporal differences (ITD), and/or interaural phase differences (IPD). All ITD and IPD combinations produced an interaural delay of 1500 microseconds at the center frequency of the noise. The interaural phase spectra were constructed to produce several patterns of putative cross-correlation functions. Potency of IIDs depended greatly on particular combinations of bandwidth, ITD and IPD. For some combinations, changing the IID by only 3 dB resulted in large shifts in laterality (sometimes moving the image from near one ear to near the other). The complex interactions observed make the results incompatible with the traditional notion that IIDs simply act as weights or scalars. Rather, IIDs act in two distinct manners: (1) as independent scalar quantities and (2) by interacting with specific combinations of bandwidth and ITD/IPD, which is believed to reflect an action within the cross correlation surface.

Acoustic Stimulation↗
PubMed1993

Identification of a cryptic t(5;7) reciprocal translocation by fluorescent in situ hybridization.

Fluorescent in situ hybridization (FISH) identified a cryptic balanced reciprocal translocation in the mother of an infant with the cri-duchat syndrome. A biotinylated probe from a flow-sorted chromosome 5 cosmid library was used to show the distal deletion of 5p15.2 in the propositus and a translocation of this segment to the distal end of 7 at 7p21 in his mother. In a subsequent pregnancy, the fetus was shown to have normal chromosomes using the same 5 cosmid library probe and a locus-specific probe derived from the 5p15.3 region. The importance of incorporating FISH into the routine diagnostic laboratory is discussed.

Adult↗
PubMed1993

Characterization of a human ovarian carcinoma cell line: UCI 101.

A new epithelial ovarian carcinoma cell line (UCI 101) has been established from the ascitic fluids and solid tumor of a patient with progressive papillary adenocarcinoma of the ovary shown previously to be refractory to combination chemotherapy consisting of cyclophosphamide, Adriamycin, and cisplatin as well as single-agent chemotherapy of taxol and high-dose cisplatin. The UCI 101 cell line grows well with an in vitro doubling time of 24 hr. The cell line expresses the B 72.3 (Tag 72), CA125, MH99 (ESA), and E29 (EMA) cell surface antigens and AE1/AE3 cytokeratins. This cell line overexpresses (as determined by immunocytochemistry) both p-glycoprotein and the epidermal growth factor receptor. The in vitro drug response to single agents including Adriamycin, cisplatin, dequalinium chloride, etoposide, 5-fluorouracil, taxol, and tumor necrosis factor was examined. Intraperitoneal transplantation of the cells into athymic mice resulted in foci of tumor on all peritoneal surfaces including the viscera and diaphragm ultimately leading to solid bulky disease with massive production of ascites. High levels of CA125 (> 500 units/ml) were detected in the serum of tumor-bearing mice. Cytogenetic analysis of cultured cells shows several marker chromosomes containing deletions, duplications, and translocations. Cytologic and histologic evaluation of the xenograft revealed morphological characteristics identical to those of the original tumor.

Animals↗
PubMed1993

Validity and reliability of three methods used in the diagnosis of Raynaud's phenomenon. The UK Scleroderma Study Group.

Three different assessment methods for the classification of Raynaud's phenomenon (RP) were compared. These were (i) a previously validated method using colour charts supplemented with a short questionnaire, (ii) answers to a questionnaire based on criteria derived from the consensus opinion of a group of clinicians, and (iii) individual clinician's assessment using standard descriptions based upon the same consensus view. We report the results of a study involving six clinicians and 30 subjects investigating the level of repeatability between the three methods and also the reliability between the six clinicians. There did not exist any overall systematic bias between the six clinicians. Further, agreement between them, as assessed by the kappa statistic, ranged from moderate to good. However, there did exist systematic bias between the results from all three of the classification approaches with agreement between them ranging from only poor to moderate. We conclude that the previously validated colour chart assessment is too insensitive to detect RP. Further, a structured questionnaire based on perceived clinician's opinion could not reproduce clinicians' classification in practice. By contrast, supplying clinicians with standard descriptions did yield a reliable classification system for RP.

Humans↗
PubMed1992

Prenatal application of fluorescent in situ hybridization (FISH) for identification of a mosaic Y-chromosome marker, idic(Yp).

An amniocentesis was performed at 13.3 weeks' gestation for advanced maternal age. A mosaic sex chromosome pattern was found: of 50 cells examined, 34 had a 45,X karyotype. In 14 cells with a modal number of 46, a recognizable Y was substituted by a small non-fluorescent marker. C-banding identified the marker as an isodicentric in 12 cells. In two cells, the non-fluorescent marker appeared to be monocentric and looked like a non-fluorescent del (Yq), but could have been an isodicentric Y with inactivation of one of the centromeres. Two cells with a modal number of 47 showed two copies of the monocentric marker. Fluorescent in situ hybridization with an alpha satellite Y-specific centromeric probe confirmed the Y-chromosome origin of the markers and allowed for more accurate prenatal diagnostic information.

Adult↗
PubMed1992

Reliability of skin involvement measures in scleroderma. The UK Scleroderma Study Group.

Two methods have been proposed to quantify the extent of skin involvement in scleroderma. These are (1) a scoring system which quantifies and summates this severity rating in 17 areas of skin surface and (2) a method estimating the percentage of skin involvement using a shaded manikin. We report on a study comparing the inter-observer reliability of these two approaches using the ratings of six clinicians on 12 patients. Systematic bias between observers was noted with both methods, but inter-observer agreement, as-assessed by the intraclass correlation coefficient (ICC), was higher with the score method. The manikin method resulted in a greater degree of disagreement between the observers, as well as a higher amount of random error, reflecting the difficulty of defining the bounds of abnormal skin. Despite the presence of bias, the score method is the preferred method for assessing the level of skin involvement.

Analysis of Variance↗
PubMed1992

Hereditary motor and sensory neuropathy type I, associated with aplasia cutis congenita: possible X-linked inheritance.

We report a family with possible X-linked recessive HMSN I with minor signs of the disease and abnormal sensory conduction studies evident in female carriers. There is a previously undescribed association with aplasia cutis congenita in both affected males, and a history of a severe skull defect in a third male child, who died at birth. The latter defect usually shows an autosomal dominant pattern of inheritance.

Adolescent↗