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Biomedical subjects

J Ma

Publications and source records attributed to J Ma.

At least 631 records · Page 35Linked to original sources
PubMed1987

A new class of yeast transcriptional activators.

We describe yeast transcriptional activators encoded by E. coli genomic DNA fragments fused to the coding sequence of the DNA-binding portion of GAL4. All of the new activating sequences that we have analyzed, like those of GAL4 and GCN4, are acidic; most of these sequences show no obvious sequence homology when compared with the identified activating regions of GAL4 and GCN4 or among themselves. We also describe a fusion protein that contains no yeast protein sequence but activates transcription in yeast.

Amino Acid Sequence↗
PubMed1987

The carboxy-terminal 30 amino acids of GAL4 are recognized by GAL80.

In wild-type yeast the action of the transcriptional activator GAL4 is inhibited by GAL80, and galactose relieves this inhibition. We show that deletion mutants of GAL4 lacking 30 amino acids of the carboxyl terminus activate transcription constitutively, whereas other deletion mutants bearing the carboxy-terminal 30 amino acids are inhibited by GAL80. Moreover, GAL4 fragments bearing these 30 amino acids, when expressed from a strong promoter on multicopy plasmids, free the endogenous GAL4 from inhibition by GAL80. These and other results suggest that GAL80 recognizes the carboxy-terminal 30 amino acids of GAL4, forming a complex that, though bound to DNA, does not activate transcription.

Amino Acid Sequence↗
PubMed1987

Deletion analysis of GAL4 defines two transcriptional activating segments.

We describe the activities of a wide array of deletion mutants of GAL4, a yeast transcriptional activator. We identify two short regions of GAL4, each of which activates transcription when fused to the DNA-binding region of the molecule. Very large portions of GAL4 are not required for gene activation.

Base Sequence↗
PubMed1985

Is hypereosinophilic syndrome a malignant disease?

A patient with an abdominal mass for 4 years developed hypereosinophilia and weight loss. Bone marrow aspirations and biopsy specimens showed hypercellularity of eosinophils. No cause for hypereosinophilia was found. Biopsy specimens of several organs, including the abdominal mass, showed eosinophilic infiltration with reactive fibrosis in some. Cytogenetic studies of the bone marrow before treatment with cytoxic drugs showed chromosomal abnormalities. Several of these have been reported in association with acute or eosinophilic leukemias. Based upon these findings, the authors believe that the patient had eosinophilic leukemia and that the abdominal mass probably was an eosinophilic chloroma.

Abdominal Neoplasms↗
PubMed1985

A colon cancer cell line (LIM1215) derived from a patient with inherited nonpolyposis colorectal cancer.

A new human colon cancer cell line (LIM1215) has been derived from a tumor arising in a member of a family known to have a high incidence of colorectal cancer. The tumor cell line is comprised of small pleomorphic cells that clone in liquid medium and form tumors in immunosuppressed mice. Ultrastructurally, the cells are capable of differentiation, with cells with multiple microvilli and cells resembling goblet cells being present in the one culture. The cells are pseudodiploid and contain a 13p+ marker chromosome.

Adenocarcinoma↗
PubMed1984

Granulocyte response to oxidized FMLP. Evidence for partial inactivation of FMLP.

We prepared FMoxLP by oxidation of FMLP and evaluated its ability to trigger a variety of granulocyte responses. FMoxLP was found to depolarize granulocyte membranes; increase granulocyte oxygen consumption, superoxide production, and hydrogen peroxide production; compete with FMLP for binding to granulocytes; and stimulate granulocyte chemotaxis. Against all of these granulocyte functions, FMoxLP was considerably less potent than the parent FMLP. When luminol-dependent-granulocyte chemiluminescence (CL) was studied, FMoxLP was observed to be a more potent stimulus of this response than FMLP. This increased CL activity of FMoxLP may be related to nonoxidative burst mechanisms. Our results indicate that FMoxLP retains a significant amount of the biological activity of FMLP (albeit in general less potent). The biological importance of the observed activities of FMoxLP must await further investigation.

Animals↗
PubMed1983

Inappropriate mucin production in endodermal carcinoma--one point of view.

The mucosal lining cells in the gastrointestinal tract respond to a threatening situation by secreting mucins manufactured during foetal life and this secretion is considered to be an early manifestation of cytogenetic instability and which may be the first step in the process of malignant transformation. Using immunohistological techniques and specific antisera against SIMA (small intestinal mucin antigen), LIMA (large intestinal mucin antigen) and CEA (carcinoembryonic antigen) the presence of these mucin antigens was studied in resected specimens from colonic, gastric and gall bladder carcinomas as well as in mucinous tumours of the ovary. Inappropriate or oncofoetal mucins were present in the majority of endodermal carcinomas, in associated metaplastic epithelium and premalignant lesions such as polyps. These antigens were also demonstrated in normal histological epithelium at some distance from the tumour. These findings lead to a better understanding of the biological behaviour of preneoplastic lesions of endodermal tissues and will aid in developing sensitive diagnostic tests for the presence of these substances.

Adenocarcinoma↗
PubMed1983

An ovarian tumour specific mucin antigen--immunohistological and biochemical studies.

A new mucin antigen was detected in a mucinous cystadenoma of human ovary. An antiserum produced in rabbits against the crude cyst fluid, following appropriate absorptions, showed immunoreactivity exclusively with tumour epithelium, particularly endocervical type epithelium. The antigen responsible for the immunoreactivity was isolated in the fraction with density 1.45g/ml following density gradient ultracentrifugation in cesium chloride, which indicated that it was indeed a glycoprotein. The native glycoprotein was very large since it was excluded from Sepharose CL-2B. The complex could be dissociated following reduction with dithiothreitol. The subunits were included in Sepharose CL-2B and the position of elution would indicate a molecular weight in the order of 1-5 x 10(6). This suggests the native antigen was a complex made up of subunits held together by disulphide bonds. Amino acid analysis of the new antigen showed a resemblance with intestinal mucins, as two-thirds of the protein consists of threonine, serine, proline, alanine and glycine. This similarity in peptide core may explain the potential of the epithelium in ovarian mucinous cystadenoma to produce inappropriate intestinal mucins during the process of malignant transformation.

Adenocarcinoma↗