Showing papers by "Johns Hopkins University School of Medicine published in 1996"
TL;DR: Improved methods of screening and therapy for glaucoma are urgently needed, as it is the second leading cause of vision loss in the world.
Abstract: AIM: To estimate the prevalence of glaucoma among people worldwide. METHODS: Available published data on glaucoma prevalence were reviewed to determine the relation of open angle and angle closure glaucoma with age in people of European, African, and Asian origin. A comparison was made with estimated world population data for the year 2000. RESULTS: The number of people with primary glaucoma in the world by the year 2000 is estimated at nearly 66.8 million, with 6.7 million suffering from bilateral blindness. In developed countries, fewer than 50% of those with glaucoma are aware of their disease. In the developing world, the rate of known disease is even lower. CONCLUSIONS: Glaucoma is the second leading cause of vision loss in the world. Improved methods of screening and therapy for glaucoma are urgently needed.
5,104 citations
TL;DR: Targeted gene disruption in the mouse shows that the Sonic hedgehog(Shh) gene plays a critical role in patterning of vertebrate embryonic tissues, including the brain and spinal cord, the axial skeleton and the limbs.
Abstract: Targeted gene disruption in the mouse shows that the Sonic hedgehog (Shh) gene plays a critical role in patterning of vertebrate embryonic tissues, including the brain and spinal cord, the axial skeleton and the limbs. Early defects are observed in the establishment or maintenance of midline structures, such as the notochord and the floorplate, and later defects include absence of distal limb structures, cyclopia, absence of ventral cell types within the neural tube, and absence of the spinal column and most of the ribs. Defects in all tissues extend beyond the normal sites of Shh transcription, confirming the proposed role of Shh proteins as an extracellular signal required for the tissue-organizing properties of several vertebrate patterning centres.
3,084 citations
TL;DR: DPC4 is identified as a candidate tumor suppressor gene whose inactivation may play a role in pancreatic and possibly other human cancers.
Abstract: About 90 percent of human pancreatic carcinomas show allelic loss at chromosome 18q. To identify candidate tumor suppressor genes on 18q, a panel of pancreatic carcinomas were analyzed for convergent sites of homozygous deletion. Twenty-five of 84 tumors had homozygous deletions at 18q21.1, a site that excludes DCC (a candidate suppressor gene for colorectal cancer) and includes DPC4, a gene similar in sequence to a Drosophila melanogaster gene (Mad) implicated in a transforming growth factor-β (TGF-β)-like signaling pathway. Potentially inactivating mutations in DPC4 were identified in six of 27 pancreatic carcinomas that did not have homozygous deletions at 18q21.1. These results identify DPC4 as a candidate tumor suppressor gene whose inactivation may play a role in pancreatic and possibly other human cancers.
2,348 citations
TL;DR: The ability of zinc to be bound specifically within a range of tetrahedral sites appears to be responsible for the evolution of the wide range of zinc-stabilized structural domains now known to exist.
Abstract: Zinc ions are key structural components of a large number of proteins. The binding of zinc stabilizes the folded conformations of domains so that they may facilitate interactions between the proteins and other macromolecules such as DNA. The modular nature of some of these zinc-containing proteins has allowed the rational design of site-specific DNA binding proteins. The ability of zinc to be bound specifically within a range of tetrahedral sites appears to be responsible for the evolution of the side range of zinc-stabilized structural domains now known to exist. The lack of redox activity for the zinc ion and its binding and exchange kinetics also may be important in the use of zinc for specific functional roles.
1,801 citations
TL;DR: It is demonstrated that functional hypoxia response elements in the promoters of the ALDA, ENO1, and Ldha genes consist of a pair of contiguous transcription factor binding sites at least one of which contains the core sequence 5′-RCGTG-3′ and is recognized by HIF-1.
1,614 citations
TL;DR: Elevations of blood pressure are a strong independent risk factor for end-stage renal disease; interventions to prevent the disease need to emphasize the prevention and control of both high-normal and high blood pressure.
Abstract: Background End-stage renal disease in the United States creates a large burden for both individuals and society as a whole. Efforts to prevent the condition require an understanding of modifiable risk factors. Methods We assessed the development of end-stage renal disease through 1990 in 332,544 men, 35 to 57 years of age, who were screened between 1973 and 1975 for entry into the Multiple Risk Factor Intervention Trial (MRFIT). We used data from the national registry for treated end-stage renal disease of the Health Care Financing Administration and from records on death from renal disease from the National Death Index and the Social Security Administration. Results During an average of 16 years of follow-up, 814 subjects either died of end-stage renal disease or were treated for that condition (15.6 cases per 100,000 person-years of observation). A strong, graded relation between both systolic and diastolic blood pressure and end-stage renal disease was identified, independent of associations between th...
1,592 citations
TL;DR: It is shown that cultured Drosophila cells transfected with a novel member of the frizzled gene family in Dfz2, respond to added Wingless protein by elevating the level of the Armadillo protein, implying that Frizzled proteins are receptors for the Wnt signalling molecules.
Abstract: Receptors for Wingless and other signalling molecules of the Wnt gene family have yet to be identified We show here that cultured Drosophila cells transfected with a novel member of the frizzled gene family in Drosophila, Dfz2, respond to added Wingless protein by elevating the level of the Armadillo protein Moreover, Wingless binds to Drosophila or human cells expressing Dfz2 These data demonstrate that Dfz2 functions as a Wingless receptor, and they imply, in general, that Frizzled proteins are receptors for the Wnt signalling molecules
1,584 citations
TL;DR: These studies provide compelling support for the view that one mechanism by which these mutant PS1 cause AD is by increasing the extracellular concentration of Abeta peptides terminating at 42(43), species that foster Abeta deposition.
1,552 citations
TL;DR: Findings identify a cellular function for RSK2 and define a mechanism whereby growth factor signals mediated by RAS and MAPK are transmitted to the nucleus to activate gene expression.
Abstract: A signaling pathway has been elucidated whereby growth factors activate the transcription factor cyclic adenosine monophosphate response element-binding protein (CREB), a critical regulator of immediate early gene transcription. Growth factor-stimulated CREB phosphorylation at serine-133 is mediated by the RAS-mitogen-activated protein kinase (MAPK) pathway. MAPK activates CREB kinase, which in turn phosphorylates and activates CREB. Purification, sequencing, and biochemical characterization of CREB kinase revealed that it is identical to a member of the pp90 RSK family, RSK2. RSK2 was shown to mediate growth factor induction of CREB serine-133 phosphorylation both in vitro and in vivo. These findings identify a cellular function for RSK2 and define a mechanism whereby growth factor signals mediated by RAS and MAPK are transmitted to the nucleus to activate gene expression.
1,263 citations
TL;DR: Results provide evidence for the involvement of HIF-1 in O2 homeostasis and represent a functional characterization of the putative O2 sensor that initiates hypoxia signal transduction leading to Hif-1 expression.
Abstract: Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric basic helix-loop-helix protein implicated in the transcriptional activation of genes encoding erythropoietin, glycolytic enzymes, and vascular endothelial growth factor in hypoxic mammalian cells. In this study, we have quantitated HIF-1 DNA-binding activity and protein levels of the HIF-1 alpha and HIF-1 beta subunits in human HeLa cells exposed to O2 concentrations ranging from 0 to 20% in the absence or presence of 1 mM KCN to inhibit oxidative phosphorylation and cellular O2 consumption. HIF-1 DNA-binding activity, HIF-1 alpha protein and HIF-1 beta protein each increased exponentially as cells were subjected to decreasing O2 concentrations, with a half maximal response between 1.5 and 2% O2 and a maximal response at 0.5% O2, both in the presence and absence of KCN. The HIF-1 response was greatest over O2 concentrations associated with ischemic/hypoxic events in vivo. These results provide evidence for the involvement of HIF-1 in O2 homeostasis and represent a functional characterization of the putative O2 sensor that initiates hypoxia signal transduction leading to HIF-1 expression.
1,205 citations
TL;DR: The magnitude ofHO-1 induction after oxidative stress and the wide distribution of this enzyme in systemic tissues coupled with the intriguing biological activities of the catalytic byproducts, carbon monoxide, iron, and bilirubin makes HO-1 a highly attractive and interesting candidate stress-response protein which may play key role(s) in mediating protection against oxidant-mediated lung injury.
Abstract: Accumulating evidence suggests that oxidative stress plays a central role in the pathogenesis of many pulmonary diseases including adult respiratory distress syndrome, emphysema, asthma, bronchopulmonary dysplasia, and interstitial pulmonary fibrosis. The morbidity and mortality of these diseases remain high even with optimal medical management. In our attempts to devise new therapies for these disorders, it is crucial to improve our understanding of the basic mechanism(s) of oxidant-induced lung injury. A major line of investigation seeks to characterize the cellular and molecular responses of the lung to oxidant insults. Much progress has been made in our understanding of the role of the "classic" antioxidant enzymes (e.g., superoxide dismutase, catalase, glutathione peroxidase) in mediating the lung's resistance against oxidant lung injury. However, it is becoming clear that other oxidant-induced gene products may also play vital roles in the lung's adaptive and/or protective response to oxidative stress. One such stress-response protein is heme oxygenase-1, HO-1. Since the identification of HO-1 in 1968, many of the studies involving this enzyme were understandably focused on the regulation and function of HO-1 in heme metabolism. This emphasis is self-evident as HO-1 catalyzes the first and rate-limiting step in heme degradation. Interestingly, however, evidence accumulated over the past 25 years demonstrates that HO-1 is induced not only by the substrate heme but also by a variety of non-heme inducers such as heavy metals, endotoxin, heat shock, inflammatory cytokines, and prostaglandins. The chemical diversity of HO-1 inducers led to the speculation that HO-1, besides its role in heme degradation, may also play a vital function in maintaining cellular homeostasis. Further support for this hypothesis was provided by Tyrrell and colleagues who showed in 1989 that HO-1 is also highly induced by a variety of agents causing oxidative stress. Subsequently, many investigators have focused their attention on the function and regulation of HO-1 in various in vitro and in vivo models of oxidant-mediated cellular and tissue injury. The magnitude of HO-1 induction after oxidative stress and the wide distribution of this enzyme in systemic tissues coupled with the intriguing biological activities of the catalytic byproducts, carbon monoxide, iron, and bilirubin, makes HO-1 a highly attractive and interesting candidate stress-response protein which may play key role(s) in mediating protection against oxidant-mediated lung injury. This review will focus on the current understanding of the physiological significance of HO-1 induction and the molecular regulation of HO-1 gene expression in response to oxidative stress. We hope that this discussion will stimulate interest and investigations into a field which is still largely uncharted in the pulmonary research community.
TL;DR: Structural features of the HIF-1α subunit that are required for heterodimerization, DNA binding, and transactivation of hypoxia-inducible factor 1 are reported.
TL;DR: It is concluded that PS1 is subject to endoproteolytic processing in vivo, and in brains of transgenic mice expressing human PS1, approximately 17 kDa and approximately 27 kDa PS1 derivatives accumulate to saturable levels, and at approximately 1:1 stoichiometry, independent of transgene-derived mRNA.
TL;DR: The modulation of GluR1 by PKA phosphorylated of Ser-845 suggests that phosphorylation of this residue may underlie the PKA-induced potentiation of AMPA receptors in neurons.
TL;DR: The data provide strong evidence of a major prostate cancer susceptibility locus on chromosome 1, and an additional set of 25 North American and Swedish families with markers in this region resulted in significant evidence of linkage in the combined set of 91 families.
Abstract: Despite its high prevalence, very little is known regarding genetic predisposition to prostate cancer. A genome-wide scan performed in 66 high-risk prostate cancer families has provided evidence of linkage to the long arm of chromosome 1 (1q24-25). Analysis of an additional set of 25 North American and Swedish families with markers in this region resulted in significant evidence of linkage in the combined set of 91 families. The data provide strong evidence of a major prostate cancer susceptibility locus on chromosome 1.
TL;DR: The hypothesis that HA fragments generated during inflammation induce the expression of macrophage genes which are important in the development and maintenance of the inflammatory response is supported.
Abstract: Hyaluronan (HA) is a glycosaminoglycan constituent of extracellular matrix In its native form HA exists as a high molecular weight polymer, but during inflammation lower molecular weight fragments accumulate We have identified a collection of inflammatory genes induced in macrophages by HA fragments but not by high molecular weight HA These include several members of the chemokine gene family: macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, cytokine responsive gene-2, monocyte chemoattractant protein-1, and regulated on activation, normal T cell expressed and secreted HA fragments as small as hexamers are capable of inducing expression of these genes in a mouse alveolar macrophage cell line, and monoclonal antibody to the HA receptor CD44 completely blocks binding of fluorescein-labeled HA to these cells and significantly inhibits HA-induced gene expression We also investigated the ability of HA fragments to induce chemokine gene expression in human alveolar macrophages from patients with idiopathic pulmonary fibrosis and found that interleukin-8 mRNA is markedly induced These data support the hypothesis that HA fragments generated during inflammation induce the expression of macrophage genes which are important in the development and maintenance of the inflammatory response
TL;DR: Results suggest that oxidative reactions catalyzed by mutant CuZnSOD enzymes initiate the neuropathologic changes in FALS.
Abstract: A subset of individuals with familial amyotrophic lateral sclerosis (FALS) possesses dominantly inherited mutations in the gene that encodes copper-zinc superoxide dismutase (CuZnSOD) A4V and G93A, two of the mutant enzymes associated with FALS, were shown to catalyze the oxidation of a model substrate (spin trap 5,5'-dimethyl-1-pyrroline N-oxide) by hydrogen peroxide at a higher rate than that seen with the wild-type enzyme Catalysis of this reaction by A4V and G93A was more sensitive to inhibition by the copper chelators diethyldithiocarbamate and penicillamine than was catalysis by wild-type CuZnSOD The same two chelators reversed the apoptosis-inducing effect of mutant enzymes expressed in a neural cell line These results suggest that oxidative reactions catalyzed by mutant CuZnSOD enzymes initiate the neuropathologic changes in FALS
TL;DR: A strong association was observed between the PlA2 polymorphism of the glycoprotein IIIa gene and acute coronary thrombosis, and this association was strongest in patients who had had coronary events before the age of 60 years.
Abstract: Background Platelet glycoprotein IIb/IIIa is a membrane receptor for fibrinogen and von Willebrand factor, and it has an important role in platelet aggregation. It is known to be involved in the pathogenesis of acute coronary syndromes. Previously, we found a high frequency of a particular polymorphism, Pl A2 , of the gene encoding glycoprotein IIIa in kindreds with a high prevalence of premature myocardial infarction. Methods To investigate the relation between the Pl A2 polymorphism and acute coronary syndromes, we conducted a case–control study of 71 case patients with myocardial infarction or unstable angina and 68 inpatient controls without known heart disease. The groups were matched for age, race, and sex. We used two methods to determine the Pl A genotype: reverse dot blot hybridization and allele-specific restriction digestion. Results The prevalence of Pl A2 was 2.1 times higher among the case patients than among the controls (39.4 percent vs. 19.1 percent, P = 0.01). In a subgroup of patients w...
TL;DR: Six out of 21 patients with primary head and neck squamous cell carcinoma were found to have one or more microsatellite alterations in serum precisely matching those in the primary tumors, representing a novel method for the detection of circulating tumor cell DNA.
Abstract: Microsatellite DNA alterations are an integral part of neoplastic progression and are valuable as clonal markers for the detection of human cancers1–3. Moreover, recent evidence suggests that senescent tumor cells may release DNA into the circulation, which is subsequently carried by and therefore enriched in the serum and plasma4,5. We tested 21 patients with primary head and neck squamous cell carcinoma (HNSCC) by polymerase chain reaction (PCR)–based microsatellite analysis of DNA from lymphocytes and paired serum samples. Patients were scored for alterations as defined by the presence of new alleles (shifts) or loss of heterozygosity (LOH) in serum at each of 12 markers and then compared with primary tumor DNA. Six out of 21 patients (29%) were found to have one or more microsatellite alterations in serum precisely matching those in the primary tumors. All six patients had advanced disease (stage III or IV); five of these patients had nodal metastases, three later developed distant metastases, and four died of disease. Microsatellite analysis of serum represents a novel method for the detection of circulating tumor cell DNA. If these results are confirmed in larger studies, microsatellite markers may be useful in assessing tumor burden in cancer patients.
TL;DR: It is demonstrated that rAAV vectors are able to transduce skeletal muscle and are capable of achieving sustained expression and systemic delivery of a therapeutic protein following a single intramuscular administration.
Abstract: Somatic gene therapy has been proposed as a means to achieve systemic delivery of therapeutic proteins. However, there is limited evidence that current methods of gene delivery can practically achieve this goal. In this study, we demonstrate that, following a single intramuscular administration of a recombinant adeno-associated virus (rAAV) vector containing the β-galactosidase (AAV-lacZ) gene into adult BALB/c mice, protein expression was detected in myofibers for at least 32 weeks. A single intramuscular administration of an AAV vector containing a gene for human erythropoietin (AAV-Epo) into mice resulted in dose-dependent secretion of erythropoietin and corresponding increases in red blood cell production that persisted for up to 40 weeks. Primary human myotubes transduced in vitro with the AAV-Epo vector also showed dose-dependent production of Epo. These results demonstrate that rAAV vectors are able to transduce skeletal muscle and are capable of achieving sustained expression and systemic delivery of a therapeutic protein following a single intramuscular administration. Gene therapy using AAV vectors may provide a practical strategy for the treatment of inherited and acquired protein deficiencies.
TL;DR: Results suggest that GKLF is potentially a negative regulator of cell growth in tissues such as the gut mucosa, where cell proliferation is intimately coupled to growth arrest and differentiation.
TL;DR: The 2.0 A crystal structure of a fragment of human fibronectin encompassing the seventh through the RGD-containing tenth type III repeats (FN7-10) is determined, revealing an extended rod-like molecule with a long axis of approximately 140 A and highly variable relationships between adjacent domains.
Journal Article•
TL;DR: It is suggested that p15INK4B is inactivated selectively in leukemias and gliomas and seems to constitute an important tumor suppressor gene loss in these neoplasms.
Abstract: The recently identified cyclin-dependent kinase inhibitor p15INK4B is localized to a region on chromosome 9p21 frequently deleted in human tumors. Previous evidence has pointed to a related gene, p16INK4A, as the principal target of this deletion. We report that in gliomas and, to a striking degree, in leukemias, the p15 gene is commonly inactivated in association with promoter region hypermethylation involving multiple sites in a 5'-CpG island. In some gliomas and all of the primary leukemias, this event occurs without alteration of the adjacent gene, p16INK4A. In other tumors, including lung, head and neck, breast, prostate, and colon cancer, inactivation of p15INK4B occurs only rarely and only with concomitant inactivation of p16. Aberrant methylation of p15INK4B is associated with transcriptional loss of this gene. Treatment with the demethylating agent 5-aza-2'-deoxycytidine leads to re-expression of p15 mRNA. In selected leukemia cell lines, p15 inactivation correlates with known resistance to the growth-suppressive effects of transforming growth factor-beta. These results suggest that p15INK4B is inactivated selectively in leukemias and gliomas and seems to constitute an important tumor suppressor gene loss in these neoplasms.
TL;DR: The present studies demonstrate that U1-70kD and DNA-PKcs are excellent substrates for apopain, with cleavage occurring at sites that are highly similar to the cleavage site within PARP.
Abstract: Proteolysis mediated by the interleukin 1 beta-converting enzyme (ICE) homologues is an important mechanism of the apoptotic process. The ICE homologue apopain/CPP-32/Yama (subsequently referred to as apopain) cleaves poly(ADP-ribose)polymerase (PARP) early during apoptosis. Additional apoptosis-specific protein cleavages have been observed in which the direct involvement of ICE-like proteases has been postulated. These substrates include the 70-kD protein component of the U1-ribonucleoprotein (U1-70kD), and the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs). The present studies demonstrate that U1-70kD and DNA-PKcs are excellent substrates for apopain, with cleavage occurring at sites that are highly similar to the cleavage site within PARP. The fragments generated from isolated protein substrates by apopain are identical to those observed in intact apoptotic cells, in apoptotic cell extracts, and in normal cell extracts to which apopain has been added. Like PARP, cleavage of these substrates in apoptotic cell extracts is abolished by nanomolar concentrations of Ac-DEVD-CHO and micromolar amounts of Ac-YVAD-CHO, confirming the involvement of apopain or an apopain-like activity. We propose that a central function of apopain or similar homologues in apoptosis is the cleavage of nuclear repair proteins, thereby abolishing their critical homeostatic functions.
TL;DR: It is demonstrated that COX-2 immunoreactivity is selectively expressed in a subpopulation of excitatory neurons in neo-and allocortices, hippocampus, and amygdala and is compartmentalized to dendritic arborizations, suggesting that COx-2, and its diffusible prostanoid products, may play a role in postsynaptic signaling of excited neurons in cortex
Abstract: Postnatal development and adult function of the central nervous system are dependent on the capacity of neurons to effect long-term changes of specific properties in response to neural activity. This neuronal response has been demonstrated to be tightly correlated with the expression of a set of regulatory genes which include transcription factors as well as molecules that can directly modify cellular signaling. It is hypothesized that these proteins play a role in activity-dependent response. Previously, we described the expression and regulation in brain of an inducible form of prostaglandin synthase/cyclooxygenase, termed COX-2. COX-2 is a rate-limiting enzyme in prostanoid synthesis and its expression is rapidly regulated in developing and adult forebrain by physiological synaptic activity. Here we demonstrate that COX-2 immunoreactivity is selectively expressed in a subpopulation of excitatory neurons in neo-and allocortices, hippocampus, and amygdala and is compartmentalized to dendritic arborizations. Moreover, COX-2 immunoreactivity is present in dendritic spines, which are specialized structures involved in synaptic signaling. The developmental profile of COX-2 expression in dendrites follows well known histogenetic gradients and coincides with the critical period for activity-dependent synaptic remodeling. These results suggest that COX-2, and its diffusible prostanoid products, may play a role in postsynaptic signaling of excitatory neurons in cortex and associated structures.
TL;DR: In this urban population of non-anaemic iron-deficient adolescent girls, iron supplementation improved verbal learning and memory andRegression analysis showed that girls who received iron performed better on a test of verballearning and memory than girls in the control group.
TL;DR: It is suggested that NuMA forms bifunctional complexes with cytoplasmic dynein and dynactin that can tether microtubules at the spindle poles and that are essential for mitotic spindle pole assembly and stabilization.
Journal Article•
TL;DR: The data suggest that inactivation of the p16 tumor suppressor gene is a frequent event in squamous cell carcinomas of the head and neck; p16 is inactivated by several distinct and exclusive events including homozygous deletion, point mutation, and promoter methylation; and immunohistochemical analysis for expression of thep16 gene product is an accurate and relatively simple method for evaluating p16 gene inactivation.
Abstract: The tumor suppressor gene p16 (CDKN2/MTS-1/INK4A) can be inactivated by multiple genetic mechanisms. We analyzed 29 invasive primary head and neck squamous cell carcinomas (HNSCC) for p16 inactivation with immunohistochemistry utilizing a new monoclonal antibody (mAb), DCS-50. p16 staining of the primary lesions was correlated with genetic analysis including: (a) detailed microsatellite analysis of markers at the p16 locus to detect homozygous deletion; (b) sequence analysis of p16; and (c) Southern blot analysis to determine the methylation status of the 5' CpG island of p16. Twenty-four of 29 (83%) head and neck squamous cell carcinoma tumors displayed an absence of p16 nuclear staining using immunohistochemistry. Of these 24 tumors, we found that 16 (67%) harbored homozygous deletions, 5 (21%) were methylated, 1 displayed a rearrangement at the p16 locus, and 1 displayed a frameshift mutation in exon 1. These data suggest that: (a) inactivation of the p16 tumor suppressor gene is a frequent event in squamous cell carcinomas of the head and neck; (b) p16 is inactivated by several distinct and exclusive events including homozygous deletion, point mutation, and promoter methylation; and (c) immunohistochemical analysis for expression of the p16 gene product is an accurate and relatively simple method for evaluating p16 gene inactivation.
TL;DR: A novel method for isolating renal cystic epithelia from single cysts is developed and used to show that individual renal cysts in ADPKD are monoclonal and the high rate at which "second hits" must occur to account for the large number of cysts observed suggests that unique structural features of the PKD1 gene may be responsible for its mutability.
TL;DR: It is demonstrated that NMDA receptor function can be regulated by direct binding of calmodulin to the NR1 subunit, and a possible mechanism for activity-dependent feedback inhibition and Ca2+-dependent inactivation of NMDA receptors is suggested.