Showing papers by "Icahn School of Medicine at Mount Sinai published in 1994"

Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine treatment. Pediatric AIDS Clinical Trials Group Protocol 076 Study Group.

Abstract: Background and Methods Maternal-infant transmission is the primary means by which young children become infected with human immunodeficiency virus type 1 (HIV). We conducted a randomized, double-blind, placebo-controlled trial of the efficacy and safety of zidovudine in reducing the risk of maternal-infant HIV transmission. HIV-infected pregnant women (14 to 34 weeks' gestation) with CD4+ T-lymphocyte counts above 200 cells per cubic millimeter who had not received antiretroviral therapy during the current pregnancy were enrolled. The zidovudine regimen included antepartum zidovudine (100 mg orally five times daily), intrapartum zidovudine (2 mg per kilogram of body weight given intravenously over a one-hour period, then 1 mg per kilogram per hour until delivery), and zidovudine for the newborn (2 mg per kilogram orally every six hours for six weeks). Infants with at least one positive HIV culture of peripheral-blood mononuclear cells were classified as HIV-infected. Results From April 1991 through Decemb...

Nomenclature of systemic vasculitides. Proposal of an international consensus conference

Abstract: The following are some of the conclusions and proposals made at the Chapel Hill Consensus Conference on the Nomenclature of Systemic Vasculitis. 1. Although not a prerequisite component of the definitions, patient age is recognized as a useful discriminator between Takayasu arteritis and giant cell (temporal) arteritis. 2. The name "polyarteritis nodosa," or alternatively, the name "classic polyarteritis nodosa," is restricted to disease in which there is arteritis in medium-sized and small arteries without involvement of smaller vessels. Therefore, patients with vasculitis affecting arterioles, venules, or capillaries, including glomerular capillaries (i.e., with glomerulonephritis), are excluded from this diagnostic category. 3. The name "Wegener's granulomatosis" is restricted to patients with granulomatous inflammation. Patients with exclusively nongranulomatous small vessel vasculitis involving the upper or lower respiratory tract (e.g., alveolar capillaritis) fall into the category of microscopic polyangiitis (microscopic polyarteritis). 4. The term "hypersensitivity vasculitis" is not used. Most patients who would have been given this diagnosis fall into the category of microscopic polyangiitis (microscopic polyarteritis) or cutaneous leukocytoclastic angiitis. 5. The name "microscopic polyangiitis," or alternatively, "microscopic polyarteritis," connotes pauci-immune (i.e., few or no immune deposits) necrotizing vasculitis affecting small vessels, with or without involvement of medium-sized arteries. Cryoglobulinemic vasculitis, Henoch-Schonlein purpura, and other forms of immune complex-mediated small vessel vasculitis must be ruled out to make this diagnosis. 6. The name "cutaneous leukocytoclastic angiitis" is restricted to vasculitis in the skin without involvement of vessels in any other organ. 7. Mucocutaneous lymph node syndrome must be present to make a diagnosis of Kawasaki disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Initial reliability and validity of a new retrospective measure of child abuse and neglect.

Abstract: OBJECTIVE: This report presents initial findings on the reliability and validity of a new retrospective measure of child abuse and neglect, the Childhood Trauma Questionnaire. METHOD: Two hundred eighty-six drug- or alcohol-dependent patients were given the Childhood Trauma Questionnaire as part of a larger test battery, and 40 of these patients were given the questionnaire again after an interval of 2 to 6 months. Sixty-eight of the patients were also given a structured interview for child abuse and neglect, the Childhood Trauma Interview, that was developed by the authors. RESULTS: Principal-components analysis of responses on the Childhood Trauma Questionnaire yielded four rotated orthogonal factors: physical and emotional abuse, emotional neglect, sexual abuse, and physical neglect. Cronbach's alpha for the factors ranged from 0.79 to 0.94, indicating high internal consistency. The Childhood Trauma Questionnaire also demonstrated good test-retest reliability over a 2- to 6-month interval (intraclass correlation = 0.88), as well as convergence with the Childhood Trauma Interview, indicating that patients' reports of child abuse and neglect based on the Childhood Trauma Questionnaire were highly stable, both over time and across type of instruments. CONCLUSIONS: These findings provide strong initial support for the reliability and validity of the Childhood Trauma Questionnaire. Language: en

Cyclosporine in Severe Ulcerative Colitis Refractory to Steroid Therapy

Abstract: Background There has been no new effective drug therapy for patients with severe ulcerative colitis since corticosteroids were introduced almost 40 years ago. In an uncontrolled study, 80 percent of 32 patients with active ulcerative colitis refractory to corticosteroid therapy had a response to cyclosporine therapy. Methods We conducted a randomized, double-blind, controlled trial in which cyclosporine (4 mg per kilogram of body weight per day) or placebo was administered by continuous intravenous infusion to 20 patients with severe ulcerative colitis whose condition had not improved after at least seven days of intravenous corticosteroid therapy. A response to therapy was defined as an improvement in a numerical symptom score (0 indicated no symptoms, and 21 severe symptoms) leading to discharge from the hospital and treatment with oral medications. Failure to respond to therapy resulted in colectomy, but some patients in the placebo group who had no response and no urgent need for surgery were subseque...

Identification of novel genes, SYT and SSX, involved in the t(X;18)(p11.2;q11.2) translocation found in human synovial sarcoma

Abstract: Human synovial sarcomas contain a recurrent and specific chromosomal translocation t(X;18)(p11.2;q11.2). By screening a synovial sarcoma cDNA library with a yeast artificial chromosome spanning the X chromosome breakpoint, we have indentified a hybrid transcript that contains 5′ sequences (designated SYT) mapping to chromosome 18 and 3′ sequences (designated SSX) mapping to chromosome X. An SYT probe detected genomic rearrangements in 10/13 synovial sarcomas. Sequencing of cDNA clones shows that the normal SYT gene encodes a protein rich in glutamine, proline and glycine, and indicates that in synovial sarcoma rearrangement of the SYT gene results in the formation of an SYT–SSX fusion protein. Both SYT and SSX failed to exhibit significant homology to known gene sequences.

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Part VI. Family history assessment: A multicenter study of first-degree relatives of Alzheimer's disease probands and nondemented spouse controls

Abstract: Although familial factors in Alzheimer9s disease (AD) are well established, uniform family-history assessment in genetic and epidemiologic studies of AD is needed to reconcile the divergent estimates of the cumulative risk of this illness among relatives of AD probands. To answer the need, the Consortium to Establish a Registry for Alzheimer9s Disease (CERAD) has developed a standardized Family History Assessment of AD to identify the presence of AD, Parkinson9s disease (PD), and Down9s syndrome (DS) in family members. This paper describes the use of this new assessment instrument in 118 patients with AD (estimated mean age at onset [± SD] = 64.5 ± 7.7 years) and their nondemented spouses who were enrolled in 11 different CERAD sites in the U.S. The first-degree relatives of the probands with AD had a significantly greater cumulative risk (p

Impaired Attention, Genetics, and the Pathophysiology of Schizophrenia

Abstract: Impaired attention is commonly observed among schizophrenia patients and those at genetic risk for the disease. This article reviews over 40 studies that used various versions of the Continuous Performance Test (CPT) as the primary measure of attention. These studies of normal subjects, affected patients, and various at-risk populations demonstrate that the CPT is a psychometrically sound procedure that consistently discriminates affected patients from controls. Sufficiently difficult versions of this task have also demonstrated that impaired attention is (1) evident in schizophrenia patients regardless of clinical state, (2) detectable before illness onset, (3) apparently heritable, (4) specific--in terms of distinct profile patterns--to schizophrenia, and (5) predictive of later behavioral disturbances in susceptible individuals. Selected studies are also discussed that examine the role of attentional deficit in the pathophysiology of schizophrenia and its potential consequences for personality development. With respect to pathophysiology, preliminary data suggest that subcortical brain dysfunction has an important role in the attentional deficits tapped by the CPT. With respect to personality, an association between chronically impaired attention and deficient social skills has been found. It is concluded that the CPT is a cost-effective measure of the attentional deficit commonly found in affected schizophrenia subjects and those at risk for the disorder, and is therefore a potentially valuable screening device for preventive intervention programs.

Heat shock proteins transfer peptides during antigen processing and CTL priming

Abstract: Recently emerging evidence indicates that the heat shock proteins (HSPs) gp96, hsp90, and hsp70 associate with antigenic peptides derived from cellular proteins. This evidence forms the basis of the following two hypotheses: 1) that HSPs constitute a relay line in which the peptides, after generation in the cytosol by the action of proteases, are transferred from one HSP to another, until they are finally accepted by MHC class I molecules in the endoplasmic reticulum, and 2) that the binding of peptides by HSPs constitutes a key step in the priming of cytotoxic T lymphocytes (CTLs) in vivo. The following chain of events is suggested: HSPs are released from virus-infected cells or tumor cells in vivo during lysis of cells during infection or by the action of antibodies or nonspecific effectors. The HSPs, which are now complexed with antigenic peptides derived from the cognate cells, are taken up by macrophage or other specialized antigen-presenting cells, possibly by a receptor-mediated mechanism. The HSP-borne peptide is then routed to the endogenous presentation pathway in the antigen-presenting cell and is displayed in the context of that cell's MHC class I, where it is finally recognized by the precursor CTLs. Thus it is suggested that, as with antigen presentation by MHC class II molecules, presentation by MHC class I molecules is also carried out primarily by the host antigen-presenting cells. This mechanism explains the phenomenon of cross-priming and has implications for the development of immunological strategies against cancer and infectious diseases.

A longitudinal study of Alzheimer's disease : measurement, rate, and predictors of cognitive deterioration

Abstract: Objective: This study measured the annual rate ofcognitive change in patients with Alzheimer’s disease and determined the effects ofclinical variables on that rate. It also compared the ability of two cognitive scales to measure change over the entire range of dementia severity. Method: The cognitive subscale of the Alzheimer’s Disease Assessment Scale and the Blessed test for information memory and concentration were given to 1 1 1 patients with Alzheimer’s disease and 72 nondemented elderly comparison subjects at 6-month intervals for up to 90 months. Longitudinal changes in scores on the cognitive subscale were measured with several different methods of data analysis. Results: For the patients with Alzheimer’s disease, the annual rate of change in cognitive subscale scores showed a quadratic relationship with dementia severity in which deterioration was slower for mildly and severely demented patients than for patients with moderate dementia. Gender, age at onset, and family history of dementia 1 had no effect on the rate of cognitive deterioration. The comparison group showed a slight improvement in cognitive performance over time. All data analytic methods gave similar results. The cognitive subscale of the Alzheimer’s Disease Assessment Scale was more sensitive to change in both mild and severe dementia than was the Blessed test. Conclusions: These results suggest that cognitive deterioration is slow during the early and very late stages of Alzheimer’s disease and more rapid during the middle stages. No clinical variables other than degree of cognitive impairment and previous rate of cognitive decline predicted rate of deterioration. These results have implications for treatment trials and attempts to identify subgroups. (Am J Psychiatry 1994; 151:390-396)

Gender in medical encounters: an analysis of physician and patient communication in a primary care setting.

Abstract: The relation of physician and patient gender to verbal and nonverbal communication was examined in 100 routine medical visits. Female physicians conducted longer visits, made more positive statements, made more partnership statements, asked more questions, made more back-channel responses, and smiled and nodded more. Patients made more partnership statements and gave more medical information to female physicians. The combinations of female physician-female patient and female physician-male patient received special attention in planned contrasts. These combinations showed distinctive patterns of physician and patient behavior, especially in nonverbal communication. We discuss the relation of the results to gender differences in nonclinical settings, role strains in medical visits, and current trends in medical education.

Structure and expression of fibrillin-2, a novel microfibrillar component preferentially located in elastic matrices

Abstract: During the previous cloning of the fibrillin gene (FBN1), we isolated a partial cDNA coding for a fibrillin-like peptide and mapped the corresponding gene (FBN2) to human chromosome 5. (Lee, B., M. Godfrey, E. Vitale, H. Hori, M. G. Mattei, M. Sarfarazi, P. Tsipouras, F. Ramirez, and D. W. Hollister. 1991. Nature [Lond.]. 352:330-334). The study left, however, unresolved whether or not the FBN2 gene product is an extracellular component structurally related to fibrillin. Work presented in this report clarifies this important point. Determination of the entire primary structure of the FBN2 gene product demonstrated that this polypeptide is highly homologous to fibrillin. Immunoelectron microscopy localized both fibrillin proteins to elastin-associated extracellular microfibrils. Finally, immunohistochemistry revealed that the fibrillins co-distribute in elastic and non-elastic connective tissues of the developing embryo, with preferential accumulation of the FBN2 gene product in elastic fiber-rich matrices. These results support the original hypothesis that the fibrillins may have distinct but related functions in the formation and maintenance of extracellular microfibrils. Accordingly, we propose to classify the FBN1 and FBN2 gene products as a new family of extracellular proteins and to name its members fibrillin-1 and fibrillin-2, respectively.

Regional, cellular, and ultrastructural distribution of N-methyl-D-aspartate receptor subunit 1 in monkey hippocampus.

Abstract: The regional, cellular, and subcellular distributions of N-methyl-D-aspartate (NMDA) receptor subunit 1, NMDAR-1, were investigated in monkey hippocampus by using a monoclonal antibody directed against a fusion protein corresponding to aa 660-811 of NMDAR-1. The data indicate that many neurons in each subfield of the hippocampus contain NMDAR-1 protein, although the intensity and distribution of immunoreactivity varied across regions, strata, and cellular compartments. In stratum lucidum of CA3, mossy fiber axons were immunoreactive for NMDAR-1, which may correspond to previously hypothesized presynaptic receptors. NMDAR-1-labeled postsynaptic profiles were present in stratum radiatum of CA3 but were largely absent from stratum lucidum. Such intraneuronal segregation of glutamate receptor subunits or classes may be spatially correlated with afferent systems that exhibit laminar segregation and terminate in different portions of the postsynaptic dendritic tree. For example, in CA3 pyramidal cells, NMDA receptors are postsynaptic in distal apical dendrites (stratum radiatum) where NMDA-dependent long-term potentiation in rats is mediated by associational/commissural afferents, and are absent from proximal apical dendrites (stratum lucidum), where NMDA-independent long-term potentiation is mediated by the mossy fiber input.

Inflammatory mechanisms in Alzheimer's disease: implications for therapy.

Abstract: Objective The purpose of this article is to review evidence that inflammatory and immune mechanisms are important in the pathophysiology of Alzheimer's disease and to suggest new treatment strategies. Method The authors review the English-language literature of the last 10 years pertaining to the pathophysiology of Alzheimer's disease. Results There is ample evidence supporting the hypothesis that inflammatory and immune mechanisms are involved in tissue destruction in Alzheimer's disease. Acute phase proteins are elevated in the serum and are deposited in amyloid plaques, activated microglial cells that stain for inflammatory cytokines accumulate around senile plaques, and complement components including the membrane attack complex are present around dystrophic neurites and neurofibrillary tangles. Conclusions Clinical trials of anti-inflammatory/immunosuppressive drugs are necessary to determine whether alteration of these inflammatory mechanisms can slow the progression of Alzheimer's disease.

Prevalence of coexistence of coronary artery disease, peripheral arterial disease, and atherothrombotic brain infarction in men and women ≥62 years of age

Abstract: Our data showed that CAD, PAD, and ABI were more prevalent in men than in women aged ≥62 years. Of our 1,886 patients, only 705 (37%) had no CAD, PAD, or ABI. CAD was present in 43%, PAD in 25%, and ABI in 26% of our population. If ABI was present, CAD was also present in 53% and PAD in 33% of our population. If PAD was present, CAD was also present in 58% and ABI in 34% of our population. If CAD was present, ABI was also present in 32% and PAD in 33% of our population.

Induction of cell migration by pro-urokinase binding to its receptor : possible mechanism for signal transduction in human epithelial cells

Abstract: A human epithelial cell line, WISH, and a mouse cell line, LB6-uPAR, transfected with the human urokinase receptor (uPAR), both expressed high affinity uPAR but undetectable levels of urokinase (uPA). In two independent assays, binding of exogenous pro-uPA produced an up to threefold enhancement of migration. The migration was time and concentration dependent and did not involve extracellular proteolysis. This biologic response suggested that uPAR can trigger an intracellular signal. Since this receptor is a glycosyl-phosphatidylinositol-linked protein, we postulated that it must do so by interacting with other proteins, among which, by analogy to other systems, would be a kinase. To test this hypothesis, we carried out a solid phase capture of uPAR from WISH cell lysates using either antibodies against uPAR or pro-uPA adsorbed to plastic wells, followed by in vitro phosphorylation of the immobilized proteins. SDS-PAGE and autoradiography revealed two phosphorylated protein bands of 47 and 55 kD. Both proteins were phosphorylated on serine residues. Partial sequence of the two proteins showed a 100% homology to cytokeratin 18 (CK18) and 8 (CK8), respectively. A similar pattern of phosphorylation was obtained with lysates from A459 cells, a lung carcinoma, but not HL60, LB6-uPAR or HEp3 cell lysates, suggesting that the identified multiprotein uPAR-complex may be specific for simple epithelia. Moreover, immunocapture with antibody to another glycosyl-phosphatidylinositol-linked protein, CD55, which is highly expressed in WISH cells, was ineffective. The kinase was tentatively identified as protein kinase C, because it was inhibited by an analogue of staurosporine more specific for PKC and not by a PKA or tyrosine kinase inhibitors. The kinase was tentatively identified as PKC epsilon because of its resistance to PMA down-modulation, independence of Ca2+ for activity, and reaction with a specific anti-PKC epsilon antibody in Western blots. Cell fractionation into cytosolic and particulate fractions revealed that all four proteins, the kinase, uPAR, CK18, and CK8, were present in the particulate fraction. In vivo, CK8, and to a lesser degree CK18, were found to be phosphorylated on serine residues. Occupation of uPAR elicited a time-dependent increase in the phosphorylation intensity of CK8, a cell shape change and a redistribution of the cytokeratin filaments. These results strongly suggest that uPAR serves not only as an anchor for uPA but participates in a signal transduction pathway resulting in a pronounced biological response.

A reciprocal mutation supports helix 2 and helix 7 proximity in the gonadotropin-releasing hormone receptor.

Abstract: Activation of the pituitary gonadotropin-releasing hormone receptor, a member of the seven-transmembrane G protein-coupled receptor (GPCR) family, triggers a cascade of events leading to gonadotropin release and stimulation of the reproductive system. An unusual feature of this receptor, observed in mice, rats, and humans, is the presence of Asn87 in the second putative transmembrane helix at the location of a highly conserved aspartate in the GPCR family and of Asp318 in the putative seventh transmembrane helix where nearly all other GPCRs have asparagine. The possibility that these residues interact was suggested by this reciprocal pattern and by a three-dimensional model of the gonadotropin-releasing hormone receptor and was investigated by site-directed mutagenesis. Replacing Asn87 in the second transmembrane domain by aspartate eliminated detectable ligand binding. A second mutation, generating the double-mutant receptor Asp87Asn318, recreated the arrangement found in other GPCRs and re-established high affinity agonist and antagonist binding. The restoration of binding by a reciprocal mutation indicates that these two specific residues in helices 2 and 7 are adjacent in space and provides an empirical basis to refine the model of the transmembrane helix bundle of the receptor.

Standardized Uptake Values of FDG: Body Surface Area Correction is Preferable to Body Weight Correction

Abstract: Standardized uptake values (SUVs) are widely used to measure 18F-fluorodeoxyglucose (FDG) uptake in various tumors. It has been reported that normalization of FDG uptake for patient body weight (SUVbw) overestimates FDG uptake in heavy patients, as their fraction of body fat (with low FDG uptake) is often increased. The objective of this study was to determine if “normalization of FDG uptake for the body surface area” (SUVbsa) is independent of the patient9s body size and is more reliable than SUVbw. Methods: FDG-PET images were acquired on 44 patients (body weight range: 45–115 kg) with cancer. SUVbw [(mCi/g of tissue)/(mCi injected/patient body weight in g)] and SUVbsa [(mCi/g of tissue)/(mCi injected/patient BSA in m2)] were determined for the liver. Since most observers are accustomed to using the SUVbw, the two values were compared by setting the mean SUVbsa equal to that of SUVbw. Results: SUVbw and SUVbsa were 3.42 ± 0.85 (mean ± s.d.) and 3.42 ± 0.60, respectively. The standard deviation of the SUVbsa was smaller than that of SUVbw. More importantly, there was a strong positive correlation between SUVbw and, not only body weight (r = 0.75) but also BSA (r = 0.68), whereas only a weak correlation between SUVbsa and body weight (r = 0.41) or BSA (r = 0.38) was found with a near flat regression line. Conclusion: SUVbw over-estimates FDG uptake in large patients. SUVbsa appears preferable to SUVbw, since it is minimally affected by the body size.

Efficacy of cyclosporine in treatment of fistula of Crohn's disease.

Abstract: Sixteen Crohn's disease patients with active fistula who had failed standard medical therapy were treated with intravenous cyclosporine. Ten patients had perirectal disease, four had enterocutaneous fistula, and two had rectovaginal fistula. Patients were initially treated with intravenous cyclosporine, 4 mg/kg/day, and then switched to oral cyclosporine, 6-8 mg/kg/day. Improvement was graded using the Present-Korelitz criteria, and success was defined as moderate to total closure of the fistula. Fourteen of 16 patients (88%) responded in the acute phase to parenteral cyclosporine. Closure of fistula occurred in seven (44%) with moderate improvement in the remaining seven (44%). Subsequently, five patients (36%) relapsed to some degree on oral cyclosporine (three severe and two mild relapses). Nine (64%) patients maintained their improvement in the chronic phase. Chronic steroids could be discontinued in 6/8 (75%) of patients. Mild side effects were common [paresthesias (75%) and hirsutism (19%)]. A single patient had severe paresthesias requiring discontinuation of therapy. Mild hypertension was noted in four (25%) and one patient (6%) had to be withdrawn because of nephrotoxicity, which reversed after stopping cyclosporine. We conclude that intravenous cyclosporine is effective therapy for perianal, rectovaginal, and enterocutaneous fistula in Crohn's disease. Its future role awaits controlled trials as well as determination of the risk-benefit ratio.

Drug treatment of hypertension in the elderly: a meta-analysis

Abstract: PURPOSE A meta-analysis of the effect of antihypertensive drug treatment on mortality and morbidity in elderly patients. DATA SOURCES A literature search of published articles from January 1980 to February 1992. STUDY SELECTION Randomized controlled trials of drug treatment of hypertension with end points for elderly patients reported separately. DATA EXTRACTION Mortality or morbidity end points or both in patients older than 59 years were pooled by determination of typical odds ratio. A meta-regression was used to study heterogeneity. RESULTS Nine major trials with 15,559 patients older than 59 years were identified. Death rates in the control group varied between 2.7% and 77.2%; stroke and coronary mortality increased with the severity-of-illness rank (P < 0.001). Overall, treated patients had an approximately 12% reduction in all-cause mortality (odds ratio, 0.88; 95% CI, 0.80 to 0.97; 953 events compared with 1069 events, P = 0.009). There was a 36% reduction in stroke mortality (odds ratio, 0.64; CI, 0.49 to 0.82; 94 events compared with 149 events, P < 0.001) and a 25% reduction in coronary heart disease mortality (odds ratio, 0.75; CI, 0.64 to 0.88; 263 events compared with 350 events, P < 0.001). Coronary morbidity was reduced 15% (odds ratio, 0.85; CI, 0.73 to 0.99; 325 events compared with 379 events, P = 0.036), and stroke morbidity was reduced 35% (odds ratio, 0.65; CI, 0.55 to 0.76; 247 events compared with 382 events, P < 0.001). CONCLUSION Overall, treatment of hypertension in elderly patients produces a significant benefit in total mortality and cardiovascular morbidity and mortality. However, this benefit may be reduced in the oldest age groups.

Fos and Jun repress transcription activation by NF-IL6 through association at the basic zipper region.

Abstract: NF-IL6 and AP-1 family transcription factors are coordinately induced by interleukin-6 (IL-6) in a cell-type-specific manner, suggesting that they mediate IL-6 signals in the nucleus. We show that the basic leucine zipper (bZIP) region of NF-IL6 mediates a direct association with the bZIP regions of Fos and Jun in vitro. This interaction does not depend on the presence of their cognate recognition DNA elements or the posttranslational modification of either partner. NF-IL6 homodimers can bind to both NF-IL6 and AP-1 sites, whereas Fos and Jun cannot bind to most NF-IL6 sites. Cross-family association with Fos or with Jun alters the DNA binding specificity of NF-IL6 and reduced its binding to NF-IL6 sites. NF-IL6 isoforms that differ in the site of translation initiation have distinct transcriptional activities. Activation of a reporter gene linked to the NF-IL6 site by NF-IL6 is repressed by Fos and by Jun in transient transfection assays. Thus, association with AP-1 results in repression of transcription activation by NF-IL6. The repression is NF-IL6 site dependent and may have a role in determining the promoter and cell type specificity in IL-6 signaling.

Deletions spanning the neurofibromatosis 1 gene: identification and phenotype of five patients.

Abstract: Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder characterized by marked variation in clinical severity. To investigate the contribution to variability by genes either contiguous to or contained within the NF1 gene, we screened six NF1 patients with mild facial dysmorphology, mental retardation, and/or learning disabilities, for DNA rearrangement of the NF1 region. Five of the six patients had NF1 gene deletions on the basis of quantitative densitometry, locus hemizygosity, and analysis of somatic cell hybrid lines. Analyses of hybrid lines carrying each of the patient's chromosomes 17, with 15 regional DNA markers, demonstrated that each of the five patients carried a deletion > 700 kb in size. Minimally, each of the deletions involved the entire 350-kb NF1 gene; the three genes--EVI2A, EVI2B, and OMG--that are contained within an NF1 intron; and considerable flanking DNA. For four of the patients, the deletions mapped to the same interval; the deletion in the fifth patient was larger, extending farther in both directions. The remaining NF1 allele presumably produced functional neurofibromin; no gene rearrangements were detected, and RNA-PCR demonstrated that it was transcribed. These data provide compelling evidence that the NF1 disorder results from haploid insufficiency of neurofibromin. Of the three documented de novo deletion cases, two involved the paternal NF1 allele and one the maternal allele. The parental origin of the single remaining expressed NF1 allele had no dramatic effect on patient phenotype. The deletion patients exhibited a variable number of physical anomalies that were not correlated with the extent of their deletion. All five patients with deletions were remarkable for exhibiting a large number of neurofibromas for their age, suggesting that deletion of an unknown gene in the NF1 region may affect tumor initiation or development.

Ectopic expression of cyclin D1 prevents activation of gene transcription by myogenic basic helix-loop-helix regulators.

Abstract: Activation of muscle gene transcription in differentiating skeletal myoblasts requires their withdrawal from the cell cycle. The effects of ectopic cyclin expression on activation of muscle gene transcription by myogenic basic helix-loop-helix (bHLH) regulators were investigated. Ectopic expression of cyclin D1, but not cyclins A, B1, B2, C, D3, and E, inhibited transcriptional activation of muscle gene reporter constructs by myogenic bHLH regulators in a dose-dependent manner. Ectopic expression of cyclin D1 inhibited the activity of a myogenic bHLH regulator mutant lacking the basic region protein kinase C site, indicating that phosphorylation of this site is not relevant to the mechanism of inhibition. Analysis of cyclin D1 mutants revealed that the C-terminal acidic region was required for inhibition of myogenic bHLH regulator activity, whereas an intact N-terminal pRb binding motif was not essential. Together, these results implicate expression of cyclin D1 as a central determinant of a putatively novel mechanism that links positive control of cell cycle progression to negative regulation of genes expressed in differentiated myocytes.