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Biomedical subjects

Y Fu

Publications and source records attributed to Y Fu.

At least 19 recordsLinked to original sources
PubMed1996

Progesterone receptor immunoreactivity at the maternofetal interface of first trimester pregnancy: a study of the trophoblast population.

The aim of our study was to localize oestrogen receptor (ER) and progesterone receptor (PR) in the trophoblast population at the maternofetal interface in early pregnancy. Rat monoclonal antibodies to human ER and PR were used to study 44 cases of chorionic villi and 82 cases of decidua using an immunocytochemical method. The PR-immunoreactive products were localized in the nuclei of syncytiotrophoblast and cytotrophoblast cells of the villi. Specific staining was also present in the cytoplasm. Villous stroma and vessels were stained occasionally. Using cytokeratin staining in an adjacent section or double staining with PR and cytokeratin, the distribution of invading trophoblast cells and their PR expression were examined. In decidual stroma, a type of interstitial cell was identified which simultaneously expressed cytokeratin and PR in the cytoplasm, indicating that the invading trophoblast cells may express PR. All extravillous populations at the interface were positive for PR, including the syncytial lining of the decidual surface, the cytotrophoblast column, the cytotrophoblast shell and the interstitial trophoblast. The immunoreactivity of PR was also localized in the nuclei of vascular endothelial cells, whereas Factor VIII was localized in the cytoplasm of the same cells, thus confirming their endothelial nature. In contrast to PR, little ER could be detected in the trophoblast cell population using anti-ER antibody D75 in our study.

Adult↗
PubMed1996

Photooxidation of troglitazone, a new antidiabetic drug.

Troglitazone (CS-045) is a new oral antidiabetic drug reported to be effective in insulin-resistant diabetes and to show antihypertensive effects. Photooxidation of troglitazone gave the quinone and quinone epoxide as the major final stable products. An intermediate observed by NMR spectroscopy was shown to be the hydroperoxydienone, which is moderately stable at room temperature. The rate constant of singlet oxygen quenching by troglitazone is 2.14 x 10(8) M(-1) s(-1) and the reaction rate constant in acetone-d6 is 8.64 X 10(6) M(-1) s(-1). Only the chroman ring of troglitazone reacts with and quenches singlet oxygen significantly, and its reactivity and products are analogous to those of alpha-tocopherol. The reactivity of CS-45 toward singlet oxygen is much larger than that of the related compounds lacking the chroman ring.

Chromans↗
PubMed1995

Identification and characterization of a novel related adhesion focal tyrosine kinase (RAFTK) from megakaryocytes and brain.

We have isolated a cDNA encoding a novel human intracytoplasmic tyrosine kinase, termed RAFTK (for a related adhesion focal tyrosine kinase). In addition, we have cloned and characterized the murine homolog of the human RAFTK cDNA. Comparison of the deduced amino acid sequences of human RAFTK and murine Raftk cDNAs revealed 95% homology, indicating that RAFTK is highly conserved between these species. The RAFTK cDNA clone, encoding a polypeptide of 1009 amino acids, has closest homology (48% identity, 65% similarity) to the focal adhesion kinase (pp125FAK). Comparison of the deduced amino acid sequences also indicates that RAFTK, like pp125FAK, lacks a transmembrane region, myristylation sites, and SH2 and SH3 domains. In addition, like pp125FAK, RAFTK contains a kinase domain flanked by large N-terminal (426 residues) and C-terminal (331 residues) domains, and the C-terminal region contains a predicted proline-rich stretch of residues. In fetal tissues, RAFTK expression was abundant in brain, and low levels were observed in lung and liver. In adult tissues, it was less restricted, indicating that RAFTK expression is developmentally up-regulated. Expression of RAFTK was also observed in human CD34+ marrow cells, primary bone marrow megakaryocytes, platelets, and various areas of brain. The human RAFTK gene was assigned to human chromosome 8 using genomic DNAs from human/rodent somatic cell hybrid lines. The mouse Raftk gene was mapped to chromosome 14, closely linked to gonadotropin-releasing hormone. Using specific antibodies for RAFTK, a approximately 123-kDa protein from the human megakaryocytic CMK cell line was immunoprecipitated. Treatment of the megakaryocytic CMK cells with thrombin caused a rapid induction of tyrosine phosphorylation of RAFTK protein. The structural features of RAFTK suggest that it is a member of the focal adhesion kinase gene family and may participate in signal transduction in human megakaryocytes and brain as well as in other cell types.

Amino Acid Sequence↗
PubMed1995

Fibrinogen alpha genes: conservation of bipartite transcripts and carboxy-terminal-extended alpha subunits in vertebrates.

All three well-studied subunits of the clotting protein fibrinogen (alpha, beta, gamma) share N-terminal structural homologies, but until recently only the beta and gamma chains were recognized as having similar globular C-termini. With the discovery of an extra exon in the human fibrinogen alpha gene (exon VI), a minor form of the alpha subunit (alpha E) with an extended beta- and gamma-like C-terminus has been identified (Fu et al., Biochemistry 31, 11968, 1992). In the present study, the polymerase chain reaction has been used to identify sequences that encode counterparts to alpha E in chicken, rabbit, rat, and baboon. The basic six-exon structure of the fibrinogen alpha genes is shown to be conserved among mammals and birds, as are the intron positions. Bipartite transcripts--still bearing an intron prior to the last exon--are found among the products of the various vertebrate fibrinogen alpha genes. The last exon represents the largest conserved segment of the gene and, in each species examined, encodes exactly 236 amino acids. The C-termini of these alpha E chains align without a single gap and are between 76 and 99% identical. Since the exon VI-encoded domain of alpha E is as well conserved as the corresponding regions of the beta and gamma chains, it follows that it is equally important and that alpha E-fibrinogen plays a vital, if as-yet unrecognized physiological role.

Amino Acid Sequence↗
PubMed1995

Structural and functional studies of the intracellular tyrosine kinase MATK gene and its translated product.

We recently cloned the cDNA which encodes a novel megakaryocyte-associated tyrosine kinase termed MATK. In this study, we have cloned and characterized the human MATK gene as well as the murine homolog of human MATK cDNA and performed functional studies of its translated product. Comparison of the deduced amino acid sequences of human and murine MATK cDNAs revealed 85% homology, indicating that MATK is highly conserved in mouse and human. The human gene consists of 13 exons interrupted by 12 introns. The genetic units which encode the SH3 and SH2 domains are located on separate exons. The putative ATP binding site (GXGXXG) is localized on exon 7, and the entire catalytic domain is subdivided into seven exons (7-13). Somatic cell hybrid analysis indicated that human MATK gene is located on chromosome 19 while the murine Matk gene is located on chromosome 10. The immediate 5'-flanking region was highly rich in GC sequences, and potential cis-acting elements were identified including several SP1, GATA-1, APRE, and APRE1. Antisense oligonucleotides directed against MATK mRNA sequences significantly inhibited megakaryocyte progenitor proliferation. Functional studies indicated that MATK can phosphorylate the carboxyl-terminal conserved tyrosine of the Src protein. These results support the notion that MATK acts as a regulator of p60c-src in megakaryocytic cells and participates in the pathways regulating growth of cells of this lineage.

Adenosine Triphosphate↗
PubMed1995

Angiographic extravasation of contrast medium in acute "spontaneous" subdural hematoma.

Acute spontaneous subdural hematoma is very rare. We have encountered four such cases and verified the arterial origin of the bleeding at operation. None of the patients had a history of head trauma, and each had developed sudden onset of headache and other neurologic deficits, which simulate other cerebrovascular diseases. CT directly revealed subdural hematoma but gave no indication as to the source of the bleeding. Cerebral angiography was performed in all cases, with three of them showing localized extravasation of the contrast material into the subdural space. The extravasation was noted usually in the late arterial phase. This is a useful finding for diagnosing this disease and localizing the bleeding point. It is expected that with more routine use of cerebral angiography in cases of acute spontaneous subdural hematoma, extravasation of the contrast medium will be seen more frequently.

Acute Disease↗
PubMed1995

Adenosine 5'-diphosphate-glucose pyrophosphorylase from potato tuber. Significance of the N terminus of the small subunit for catalytic properties and heat stability.

cDNAs encoding the large subunit and a possibly truncated small subunit of the potato tuber (Solanum tuberosum L.) adenosine 5'-diphosphate-glucose pyrophosphorylase have been expressed in Escherichia coli (A.A. Iglesias, G.F. Barry, C. Meyer, L. Bloksberg, P.A. Nakata, T. Greene, M.J. Laughlin, T.W. Okita, G.M. Kishore, J. Preiss, J Biol Chem [1993] 268: 1081-1086). However, some properties of the transgenic enzyme were different from those reported for the enzyme from potato tuber. In this work, extension of the cDNA was performed to elongate the N terminus of the truncated small subunit by 10 amino acids. This extension is based on the almost complete conservation seen at the N-terminal sequence for the potato tuber and the spinach leaf small subunits. Expressing the extended cDNA in E. coli along with the large subunit cDNA yielded a transgenic heterotetrameric enzyme with similar properties to the purified potato tuber enzyme. It was also found that the extended small subunit expressed by itself exhibited high enzyme activity, with lower affinity for activator 3-phosphoglycerate and higher sensitivity toward inorganic phosphate inhibition. It is proposed that a major function of the large subunit of adenosine 5'-diphosphate-glucose pyrophosphorylases from higher plants is to modulate the regulatory properties of the native heterotetrameric enzyme, and the small subunit's major function is catalysis.

Amino Acid Sequence↗
PubMed1995

In vitro determination of optimal antifungal combinations against Cryptococcus neoformans and Candida albicans.

There is currently no rapid, reliable, and reproducible in vitro technique to describe the growth-inhibitory interactions of antifungal drug combinations over a wide range of drug concentrations. We have developed a microdilution plate assay that was used to determine optimal drug combinations and concentrations of one-, two-, and three-drug regimens of amphotericin B (AmphB), fluconazole (FLU), and 5-fluorocytosine (5FC) for growth inhibition of three isolates each of Cryptococcus neoformans and Candida albicans. These growth inhibition data were then used in a multifactorial design technique to (i) generate contour and surface response plots to aid visual interpretation and (ii) develop mathematical equations describing the growth responses of the fungi to a wide range of antifungal concentrations and ratios. Our data indicated that (i) antifungal drug-drug interactions affecting yeast growth are complex functions of the drugs used in combination, their absolute concentrations, and also their relative (proportional) concentrations; (ii) AmphB-FLU combinations had additive effects against C. albicans over wide concentration ranges for each agent but were indifferent (i.e., were less than additive) in their inhibitory effect on C. neoformans; (iii) other two-drug combinations (FLU-5FC or AmphB-5FC) had indifferent effects on the growth of both fungi; and (iv) three-drug combinations (AmphB-FLU-5FC) showed an additive inhibitory effect on the growth of both C. albicans and C. neoformans. The finding that no antagonism was observed in combinations employing AmphB and FLU in this in vitro model is of critical importance since it argues against the current theoretical concept, based on the individual drug's mode of action, of antagonism between these two drugs. These microdilution techniques provide a method to determine rational regimens of antifungal agents in multidrug combinations for future testing to correlate in vitro activity with in vivo response. The use of this approach has made the evaluation of complex antifungal drug-drug interactions possible and provided important new information to the evolving field of antifungal drug combination.

Amphotericin B↗
PubMed1995

Migration of a subduroperitoneal shunt catheter into the subdural space--case report.

An 82-year-old male with intractable bilateral chronic subdural hematomas was treated by emplacement of bilateral subduroperitoneal shunts on the left in 1990 and on the right in 1991. Chronic subdural hematoma recurred in 1992 due to an unusual migration of a shunt catheter into the subdural space. This migration was probably due to inadequate fixation of the shunt. Shunt replacement and fixation with an anchoring wing has resulted in no further complications for 2 years.

Aged↗
PubMed1995

[Effects of pregnant exposure to electromagnetic field emitted by electric blankets on brain catecholamine and behavior in offspring mice].

NIH pregnant mice were exposed to electromagnetic field emitted by electric blankets with 1-1.2kV/m and 0.2-0.4microT for five hours daily during their whole gestational period. Catecholamine (CA) content in the hypothalamus of their newborn offsprings was quantitatively measured with histochemical methods, and their varied behavioral activities were determined with behavioral toxicological methods. Results showed catecholamine content in exposed offsprings decreased significantly not only seven days but also 40 days after delivery as compared with the controls (P < 0.01 and P < 0.05, respectively).

Animals↗
PubMed1995

[Relation between selenium and cancer of uterine cervix].

Selenium (Se) concentration in serum, hair, normal cervix tissue or tissue of cervix cancer of 20 cases with cancer of uterine cervix (survey group), 21 with myoma of the uterus and 1 with cervical polys (control group), but also in rice, water and soil in the high and low incidence areas of cervical cancer was determined. The results showed that Se concentration in serum and cancer tissue of uterine cervix in patients with cancer of uterine cervix was significantly lower than that in the control group (P < 0.05), but no significant difference of Se concentration in hair was observed (P > 0.05), However Se concentration in rice, water and soil in the high incidence areas of cervical cancer was significantly lower than that in the low incidence areas (P < 0.05). Se deficiency may play a role in the carcinogenesis of uterine cervix.

Adenocarcinoma↗
PubMed1995

[Immune function of red blood cell (RBC) in patients with obstructive jaundice].

Twenty-six patients with obstructive jaundice were investigated for RBC immune function. It was found that C3b receptor's E rosette forming rate in jaundiced patients was significantly lower than that of nonjaundiced patients, and the C3b receptor's E rosette forming inhibitory rate was higher than that of nonjaundiced patients. The RBC immune function disturbance may contribute to the postoperative sepsis in jaundiced patients.

Adult↗
PubMed1995

[Chemical constituents of Stellera chamaejasme L].

Twelve compounds were isolated from the roots of Stellera chamaejasma. Five of them were elucidated by spectroscopic and chemical methods as 3', 14-dimethyl-4', 11-dimethoxy-5, 7-dihydroxybenzoflavanone (10), daphnetin (1), umbelliferone (2), daucosterol (5) and beta-sitosterol (3). Compound 10 is new. Compounds 1, 2, 5, 10 were isolated for the first time from S. chamaejasme.

Benzoflavones↗
PubMed1995

[Relationship between the rate of parasitic infection and the knowledge of prevention].

The relationship between the rate of parasitic infection and the level of knowledge of prevention was studied among 5479 persons allocated to 12 randomly selected groups. Stools were examined for parasitic infection by using Kato-Katz, iodine direct smear amd tube culturing methods. Children under 15 were examined for Enterobius infection by cellophane tape method. Individuals were considered infected when any parasite species was found in the stool and the infection rate was computed. The score on knowledge of prevention was measured by devising a questionnaire comprising 11 questions on parasitic disease transmission, clinical signs and prevention methods. Ten marks were given for each question correctly answered. The result of the investigation showed that the total infection rate was 52.2% and there was no significant difference between males and females (X2 = 1.94, P > 0.05). The infection rate increased with a decrease in the level of education and the highest was found in 5-year-old age group. There were altogether 7 species of parasites detected in all age groups. The infection rate of Ascaris lumbricoides was 31.3%; Trichuris trichiura, 34.1%; hookworm, 5.3%; Enterobius vermicularis, 20.3%(227+1 117); Fasciolopsis buski, 0.8%; Entamoeba coli, 0.8%; Giardia lamblia, 0.2%. The average score on knowledge was 41.9, being significantly higher in males than in females. Analysis for the age distribution showed that the highest score was found in 15-year-old age group. The data of infection rate of different parasites were converted by arcsine transformation and compared with the average score, showing that there were negative relations between the average score and the infection rate of Trichuris, hookwork, Entamoeba and the total incidence. The value of r was --0. 5534, --9.5557, --0.6091 and --0.604. respectively. The number of parasite species infecting individuals was also found to have negative relation to the score on knowledge of prevention.

Adolescent↗
PubMed1994

Cytokine production by primary bone marrow megakaryocytes.

Primary human bone marrow megakaryocytes were studied for their ability to express and release cytokines potentially relevant to their proliferation and/or differentiation. The purity of the bone marrow megakaryocytes was assessed by morphologic and immunocytochemical criteria. Unstimulated marrow megakaryocytes constitutively expressed genes for interleukin-1 beta (IL-1 beta), IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNF-alpha), by the polymerase chain reaction (PCR) and Northern blot analysis. At the protein level, megakaryocytes secreted significant amounts of IL-1 beta (53.6 +/- 3.6 pg/mL), IL-6 (57.6 +/- 15.6 pg/mL), and GM-CSF (24 +/- 4 pg/mL) but not TNF-alpha. Exposure of human marrow megakaryocytes to IL-1 beta increased the levels of IL-6 (87.3 +/- 2.3 pg/mL) detected in the culture supernatants. Transforming growth factor-beta was also able to stimulate IL-6, IL-1 beta, and GM-CSF secretion, but was less potent than stimulation with phorbol-12-myristate-13-acetate (PMA). The secreted cytokines acted additively to maintain and increase the number of colony-forming unit-megakaryocytes colonies (approximately 35%). These studies demonstrate the production of multiple cytokines by isolated human bone marrow megakaryocytes constitutively or stimulated in vitro. The capacity of human megakaryocytes to synthesize several cytokines known to modulate hematopoietic cells supports the concept that there may be an autocrine mechanism operative in the regulation of megakaryocytopoiesis.

Bone Marrow↗
PubMed1994

Abnormal class I assembly and peptide presentation in the nonobese diabetic mouse.

Presentation of self-antigens by major histocompatibility complex (MHC) class I molecules requires the function of the MHC class II-linked genes Tap-1 and Tap-2. Evidence suggests that interruption of self-peptide presentation results in reduced cell surface expression of MHC class I molecules and the interruption correlates with progression to diabetic autoimmunity in nonobese diabetic (NOD) mice and humans. NOD mice possess a rare Tap-1 allele (Tap-1b); this is associated with reduced Tap-1 mRNA abundance in lymphocytes from diabetes-prone females and decreased conformationally correct class I molecules on the cell surface. In this study, we demonstrate that, similar to lymphoma cell lines with mutations in Tap-1 or Tap-2, the reduced expression of class I molecules on the surface of lymphocytes from diabetes-prone female NOD mice was normalized by incubation at low temperatures or by exposure to class I allele-specific peptides. As would be expected for cells that express surface class I molecules not associated with peptide, female NOD lymphocytes were resistant to lysis by class I-restricted, peptide-specific cytotoxic T lymphocytes. Furthermore, the rate of class I exit from the endoplasmic reticulum of lymphocytes from female NOD mice was delayed as demonstrated by delayed glycosylation. Male NOD mice, which are not prone to diabetes, lacked these functional defects in class I assembly and had near-normal levels of Tap-1 mRNA and exhibited normal density of class I epitopes that were peptide filled. These results are consistent with the possibility that the rare Tap-1b allele is associated with a quantitative defect in Tap-1 expression that influences disease course.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

p130/pRb2 has growth suppressive properties similar to yet distinctive from those of retinoblastoma family members pRb and p107.

The retinoblastoma tumor suppressor gene product, as well as its related protein p107, has been shown clearly to exert its growth suppressive effects in a cell cycle dependent manner. In this study we demonstrate that the introduction of our recently cloned Rb family member p130/pRb2 causes growth arrest in three tumor cell lines. In addition, in the nasopharyngeal carcinoma derived cell line HONE-1, we identified a low level of expression of p130/pRb2, possibly due to gene rearrangement, and a drastic reduction in proliferation upon introduction of a constitutive active p130/pRb2 complementary DNA clone. Furthermore, we were able to dissect distinct properties of the Rb family by demonstrating that p130/pRb2 inhibits proliferation of the glioblastoma cell line T98G, which is resistant to the growth suppressive effects of both pRb and p107. Our studies demonstrate that the Rb family proteins identified to date may complement each other but they are not fully functionally redundant.

Cell Division↗