Search PubMed⌕ Search

Biomedical subjects

M E Ross

Publications and source records attributed to M E Ross.

At least 73 records · Page 4Linked to original sources
PubMed1991

Characterization of a family of high-molecular-weight plasminogen activators secreted by a lung tumor cell line.

In an earlier publication (Harvey, et al. (1982) J. Biol. Chem., 257, 5645-5651) the discovery of a family of unusually large molecules with plasminogen activator activity in the conditioned medium of a human lung cancer cell line was reported. These molecules are related to urokinase (uPA) by functional and immunological criteria. We have now purified two representatives of this glycoprotein family of Mr 900,000 (PA900) and Mr 660,000 (PA660). While these could be fractionated into subspecies exhibiting size and charge differences, reduction yielded in all cases two predominant chains of 70 and 40 kDa, respectively. Since the amino acid composition of the subfractions was identical, we conclude that the heterogeneity is due to demonstrated differences in glycosylation. The amino acid composition of the unreduced species and of the major reduced chains differed from that of 55 kDa uPA. These enzymes are active toward the substrate, plasminogen, as well as toward the uPA-specific synthetic substrate, Spectrozyme UK, and these activities are inhibitable by diisopropylphosphorofluoridate (DFP). Treatment of PA660 with [3H]DFP resulted in the incorporation of 1.4 mol of DFP into 1 mol of enzyme, suggesting the presence of a single active site. The label was quantitatively recovered in a 21 kDa fragment in a reduction experiment. This fragment also demonstrated immunological reactivity with antiurokinase. It is postulated that PA660 is composed of five or six pairs of the 70 and 40 kDa chains, and of a single uPA-like entity. All of these chains are linked by disfulfide bonds. Whether larger portions of uPA are also present in this molecule, is not yet clear. By electron microscopy, PA900 shows a filamentous structure, while PA660 is predominantly globular. The occurrence of large uPA-like activators in extracts of human colon carcinomas that crossreact with monospecific antibody against uPA, is discussed.

Amino Acids↗
PubMed1990

Meander tail reveals a discrete developmental unit in the mouse cerebellum.

Analyses of phenotypic mutations with altered patterns of cellular organization in invertebrate systems have lead to the identification of genes important to histogenesis. Efforts to identify genes defining segments or compartments in mammalian systems and demonstrate a role for such genes in the establishment of the cellular architectonics of the brain have been hampered by the absence of phenotypic mutations that reveal compartments. Evidence is presented that in the cerebellum of the mutant mouse, meander tail, there is an abrupt transition from the normal cytoarchitecture seen in the posterior lobes to a severely disorganized cellular pattern. Thus, in the anterior lobes the Purkinje cells are positioned randomly throughout the cortex, and other cellular layers, including the internal granule cell layer, do not form. In addition, radial Bergmann glial processes are virtually absent. One explanation for the discrete boundary of the affected area in the anterior portion of this mutant cerebellar cortex is that the meander tail gene influences compartmental cellular organization in mammalian brain.

Animals↗
PubMed1990

Identification of a functional glucocorticoid response element in the phenylethanolamine N-methyltransferase promoter using fusion genes introduced into chromaffin cells in primary culture.

The rat gene encoding phenylethanolamine N-methyltransferase (PNMT) was cloned and a consensus sequence for a glucocorticoid response element (GRE) was found at -513 bp, 5' to the transcriptional start site. In order to define the function of this element, fusion genes containing the PNMT promoter and a chloramphenicol acetyltransferase (CAT) reporter gene were constructed. These constructs did not express after transfection into any of 7 continuous cell lines, none of which endogenously produce PNMT. A system for transfecting chromaffin cells in primary culture was therefore devised using constructs containing 200 bp of the proenkephalin (ENK) promoter, whose expression characteristics are well known. pENK beta GAL-1, containing the ENK promoter with a lac Z reporter, was introduced into these cells and beta-galactosidase activity was visualized in situ. Approximately 90% of cells transfected were chromaffin; transfection efficiency was 5%. High levels of CAT activity were measured in chromaffin cells transfected with pENKAT12, possessing a CAT reporter. In contrast to tumor cell lines, pENKAT12 induction in these cells by forskolin and phorbol esters did not require a phosphodiesterase inhibitor. In this chromaffin system, both basal and regulated expression of the PNMT fusion genes were detected. Dexamethasone (dex) induced expression of pPNMT3000 and pPNMT900, containing the putative GRE and 3000 bp or 863 bp of PNMT promoter sequence, 4- to 10-fold. Expression of pPNMT300 and pPNMT100, which lack the GRE and contain 273 bp or 99 bp of PNMT promoter sequence, was unaffected by dex. Addition of the PNMT region spanning -490 to -863 bp conferred full dex responsiveness to a thymidine kinase promoter. Deletion of the putative GRE sequence by site-directed mutagenesis abolished the dex response. These data identify the sequence at -513 bp in the rat PNMT gene as a functional, positively acting GRE. Primary cultures of bovine chromaffin cells provide a biologically relevant expression system for transcriptional studies of catecholamine genes and their related neuropeptides.

Animals↗
PubMed1988

Proteins bound at adjacent DNA elements act synergistically to regulate human proenkephalin cAMP inducible transcription.

Synthesis of the endogenous opioid precursor, proenkephalin, is regulated by neurotransmitters and membrane depolarization. These events act through second messenger dependent signal transduction pathways via a short inducible DNA enhancer to regulate transcription of the proenkephalin gene. Two DNA elements located within this enhancer are essential for the transcriptional response to cAMP and phorbol ester. Inactivation of either element by mutation or by alteration of their stereospecific alignment eliminates inducible enhancer activity. The promoter distal element, ENKCRE-1, in the absence of a functional adjacent ENKCRE-2 element, has no inherent capacity to activate transcription. However, in the presence of a functional ENKCRE-2 element, this element synergistically augments cAMP and phorbol ester inducible transcription. The promoter proximal element, ENKCRE-2, is essential for both basal and regulated enhancer function. Four different protein factors found in HeLa cell nuclear extracts bind in vitro to the enhancer region. ENKTF-1, a novel enhancer binding protein, binds to the DNA region encompassing ENKCRE-1. The transcription factors AP-1 and AP-4 bind to overlapping sites spanning ENKCRE-2, and a fourth transcription factor, AP-2, binds to a site immediately downstream of ENKCRE-2. The binding of ENKTF-1 to mutant ENKCRE-1 sequences in vitro correlates with the in vivo inducibility of the mutant elements suggesting that ENKTF-1 acts in combination with factors that recognize the ENKCRE-2 domain to regulate cAMP inducible transcription. Together, the two DNA elements, ENKCRE-1 and ENKCRE-2 and the protein factors with which they interact, play a critical role in the transduction and reception of signals transmitted from cell surface receptors to the proenkephalin nuclear transcription complex.

Cyclic AMP↗
PubMed1985

Late-onset Wilson's disease with neurological involvement in the absence of Kayser-Fleischer rings.

We report a patient with Wilson's disease whose case is unusual in two respects. First, the patient was 58 years of age when the diagnosis was made based on urinary, serum, and hepatic copper studies, as well as liver histological investigation. Second, despite the patient's neurological impairment, Kayser-Fleischer rings had not developed. We conclude that in patients with chronic, degenerative neurological disease, particularly when associated with hepatic dysfunction, the diagnosis of Wilson's disease should be considered regardless of age at onset or the absence of Kayser-Fleischer rings on slit lamp examination.

Age Factors↗
PubMed1985

Genes for neurotransmitter synthesis, storage, and uptake.

We found that the catecholamine biosynthetic enzymes tyrosine hydroxylase (TH) (EC 1.14.16.2), dopamine beta-hydroxylase (EC 1.14.17.1), and phenylethanolamine N-methyltransferase (EC 2.1.1.28) share similar protein domains in their primary structures and that they share common gene coding sequences. In a recent report we also demonstrated that antiserums directed against choline acetyltransferase (EC 2.3.1.6), glutamic acid decarboxylase (EC 4.1.1.15), and TH cause specific complement-mediated lysis of cholinergic, gamma-aminobutyric acid-ergic, and dopaminergic subpopulations of synaptosomes, respectively. This interaction of specific antibodies to the specific subpopulation of synaptosomal membrane, e.g., recognition of antibody to TH to only the dopaminergic subpopulation of synaptosomal membrane protein, indicates that the neurotransmitter enzyme and membrane protein of its own synaptosomes may also share common protein domains. Therefore, we postulate that the specific neurotransmitter biosynthetic enzyme and a certain membrane protein of the nerve endings may share similar gene coding sequences, and that expression of these proteins may determine the phenotype of the neuron.

Amino Acids↗
PubMed1985

Fifty years ago.

Explore the source record for details and available documents.

History, 20th Century↗
PubMed1984

Biochemistry and molecular biology of catecholamine neurons: a single gene or gene family hypothesis.

We postulate that the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH), dopamine B-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) are coded for by similar gene coding sequence(s). This is based on the following observations: (1) proteolytic digestion of these enzymes produces similar peptides whose amino acid composition is nearly identical; (2) antibodies to each enzyme coprecipitate more than one of these enzymes from in vitro poly(A)mRNA translation products; (3) using hybrid selection analysis to positively identify the cDNA clones, we discovered that DBH cDNA clones cross-hybridize with PNMT mRNA, and PNMT cDNA cross-hybridize with DBH mRNA; (4) DNA hybridization analysis demonstrated that DBH and PNMT cDNA probes hybridized to several common restriction fragments of total cellular DNA. The evidence suggests that these enzymes are coded for by a single gene or linked genes coding for all catecholamine enzymes.

Amino Acid Sequence↗
PubMed1983

Immunohistochemical localization of choline acetyltransferase using a monoclonal antibody: a radioautographic method.

Monoclonal antibodies to rat striatal choline acetyltransferase were produced by fusion of sensitized mouse lymphocytes with murine plasmacytoma (NS1) cells. Two stable anti-choline acetyltransferase lines were established by limiting dilution cloning. Specificity of antibody was established by the following criteria: (1) on an enzyme linked immunosorbant assay, antibodies reacted against choline acetyltransferase which was highly purified; (2) by immunoprecipitation, monoclonal antibody bound to its antigen and precipitated choline acetyltransferase activity from solution, when used in conjunction with rabbit antimouse IgG; and (3) monoclonal antibody was shown to specifically localize cholinergic neurons. The monoclonal antibody to choline acetyltransferase was radiolabeled in culture by incubating hybridomas in medium containing 3H-labeled amino acids. This 3H-labeled antibody was used for radioautography on cryostat sections of rat peripheral and central nervous systems. In a sampling of areas, highly specific labeling of cholinergic structures was afforded at both light and electron microscopic levels. Double labeling of tyrosine hydroxylase, a catecholaminergic marker, and choline acetyltransferase was carried out by reacting sections first with the 3H-labeled antibody to choline acetyltransferase and then with rabbit antibody to tyrosine hydroxylase. The choline acetyltransferase label was radioautographically processed and tyrosine hydroxylase was visualized by the peroxidase-antiperoxidase method. The combined techniques of peroxidase and radioautographic histochemistry provide permanent electron dense labels which can be examined simultaneously within a single histologic section.

Animals↗
PubMed1982

Antibodies to rat choline acetyltransferase for immunochemistry and immunocytochemistry.

Choline acetyltransferase was purified from rat striata by several sequential column chromatographic separations on Sepharose 4B, hydroxylapatite, Sephadex G-150 and CM-Sephadex, and finally by elution of enzymatically active protein from gel slices. Conventional rabbit and monoclonal antibodies to the enzyme were produced. Monoclonal antibodies were radiolabeled in vivo and used for specific immunoradioautographic localization of choline acetyltransferase in cholinergic neurons by light and electron microscopy.

Animals↗
PubMed1981

Monoclonal antibodies to tyrosine hydroxylase: production and characterization.

Monoclonal antibodies were produced against tyrosine hydroxylase (TH), the enzyme catalyzing the rate limiting step in catecholamine neurotransmitter synthesis. An enzyme linked immunosorbant assay was used to detect the presence of specific antibody in culture. Specificity of the antibodies is characterized. These monospecific antibodies were used for immunoprecipitation and immunohistochemical staining of TH in brain.

Animals↗
PubMed1978

Primary extranodal lymphoma: response to treatment and factors influencing prognosis.

The cumulative 10 year lymphoma experience of a teaching hospital and two of its affiliated institutions was reviewed. From this group, a series of 39 cases of regionally localized primary extranodal lymphomas (Ann Arbor Stages IE and IIE) were selected for study. This group of patients was analyzed for response to initial curative treatment and factors influencing prognosis. The disease-free survival rate following initial treatment is 41% and the rate is 51% if those treated for a single relapse are included. Factors which clearly influence prognosis in this group are stage (extent of disease) at presentation and Rappaport histologic subclassification. The relationships of anatomic site and age to prognosis independent of other factors are unclear. There appears to be an association between sites of involvement in Waldeyer's Ring and the gastrointestinal tract seen both initially and in sites of relapse. An analysis of relapse patterns revealed that 33% of relapses occur as solitary extranodal "skip" recurrences that when treated with radical local treatment may result in long disease-free survival. The latter is one of several findings which suggest that a modification of the current Ann Arbor staging system may be necessary to encompass certain unique features of this group of tumors.

Adolescent↗
PubMed1977

Human kidney gamma-glutamyl transpeptidase. Catalytic properties, subunit structure, and localization of the gamma-glutamyl binding site on the light subunit.

Human kidney gamma-glutamyl transpeptidase has been purified by a procedure involving Lubrol extraction, acetone precipitation, treatment with bromelain, and column chromatography on DEAE-cellulose and Sephadex G-150. The final preparation is a glycoprotein (molecular weight of approximately 84,000) composed of two nonidentical glycopeptides (molecular weights of 62,000 and 22,000). The isozymic forms, separable by isoelectric focusing, have different contents of sialic acid. The utilization of L-glutamine (which is both a gamma-glutamyl donor and acceptor) is stimulated about 3-fold by maleate in contrast to 10-fold stimulation of glutamine utilization by the rat kidney enzyme. The gamma-glutamyl analogs, 6-diazo-5-oxo-L-norleucine (DON) and L-azaserine inactivate the human kidney enzyme with respect to its transpeptidase and hydrolase activities. Inactivation is prevented by gamma-glutamyl substrates (but not by acceptor substrates) and is accelerated by maleate. [14C]DON reacts covalently and stoichiometrically at the gamma-glutamyl site, which was localized to the light subunit of the enzyme. The light subunit of human transpeptidase closely resembles that of rat kidney enzyme in having the gamma-glutamyl binding site, and similar molecular weight and amino acid composition. The heavy subunits of the two enzymes are markedly different in both molecular weight and amino acid content; this may account for differences observed in acceptor amino acid specificity and in the magnitude of the maleate effect.

Amino Acids↗
PubMed1977

Epidermoid splenic cysts.

Five young women were treated by splenectomy for epidermoid cysts of the spleen. They all had vague abdominal symptoms, and had a mass palpable in the left upper quadrant of the abdomen. The hematologic indices were unremarkable. The diagnosis was suggested by routine radiologic examinations (including chest roentgenogram, upper gastrointestinal x-ray series, barium enema, and excretory urogram). It was confirmed in one patient by gray-scale ultrasonography, and in another by selective splenic arteriography. Of the true cysts of the spleen, the epidermoid cyst is the rarest, representing 10% of the benign, nonparaslitic cysts. The symptoms are completely relieved by splenectomy, and this remains the treatment of choice.

Adolescent↗
PubMed1976

Changes in serum salivary isoamylases in Sjögren's Syndrome.

Quantitative polyacrylamide disk gel electrophoresis of sera from 27 patients with Sjögren's syndrome (SS) and 12 comparable normal subjects revealed that serum amylase activity in patients with SS varies due to changes in the salivary isoenzyme, while pancreatic isoamylase remains normal. The SS group can be divided into those patients with markedly increased salivary isoamylase and those with normal or low salivary isoamylase. At this time we cannot be certain whether this reflects different stages in a progressive disorder, or differences in the underlying pathologic processes. Analysis of amylase isoenzymes in serum previously has been shown to be of value in pancreatic disorders, and we have now demonstrated that changes in the salivary glands may also be relected in serum amylase isoenzymes. Study of patients with other salivary and pancreatic disorders will be needed to define the clinical utility of amylase isoenzyme analysis.

Adult↗