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W C Ho

Publications and source records attributed to W C Ho.

32 records · Page 2Linked to original sources
PubMed1989

Reclustering of scattered Golgi elements occurs along microtubules.

Depolymerization of the interphase microtubules by nocodazole results in the scattering and apparent fragmentation of the Golgi apparatus in Vero fibroblast cells. Upon removal of the drug, the interphase microtubules repolymerize, and the scattered Golgi elements move back to the region around the microtubule-organizing center (MTOC) within 40 to 60 min. Using a fluorescent lipid analogue (C6-NBD-ceramide) as a vital stain for the scattered Golgi elements, their relocation was visualized by video-enhanced fluorescence microscopy in Vero cells maintained at 20 degrees C. The NBD-labeled structures were identified as Golgi elements by their colocalization with galactosyltransferase in the fixed cells. During reclustering, NBD-labeled Golgi elements were observed to move by discontinuous saltations towards the MTOC with velocities of 0.1 to 0.4 micron/s. Paths along which Golgi elements moved were super-imposable on microtubules visualized by indirect immunofluorescence. Neither the collapse of intermediate filaments caused by microinjection of antibodies to vimentin nor the disruption of microfilaments by cytochalasin D had an effect on the reclustering of Golgi elements or the positioning of the Golgi apparatus. These data show that scattered Golgi elements move along microtubules back to the region around the MTOC, while neither intact intermediate filaments nor microfilaments are involved.

4-Chloro-7-nitrobenzofurazan↗
PubMed1986

Biochemical characterization of the adhesion-related differentiation antigen XT-1.

The XT-1-molecule, an adhesion-related differentiation antigen of male mouse germ cells, is a 34 000 Mr glycoprotein with major charge isomer at pI 5.1 and is an integral component of the cell membrane. On large late pachytene spermatocyte, the molecule is present at a concentration of 2.5 X 10(3) molecules micron-2, which approximates HLA/ABC concentration on lymphocytes. By comparing the reactivity of four anti-XT-1 monoclonal antibodies, three of which elicit germ cell-germ cell adhesion, we have defined two distinct surface regions of the XT-1-molecule. The relationship of the XT-1-molecule with other known adhesion-related molecules and testicular antigens is discussed.

Animals↗
PubMed1986

The effect of preservation of chordae tendineae on mitral valve replacement for postinfarction mitral regurgitation.

Fifty-one consecutive patients underwent mitral valve replacement for mitral regurgitation secondary to myocardial infarction. Fifteen patients were in cardiogenic shock when operated on, 22 were in NYHA functional class IV, and 14 were in class III. Mitral valve replacement with preservation of the chordae tendineae and papillary muscles was performed in 10 patients in cardiogenic shock and 22 patients who had elective surgery. Concomitant procedures included repair of left ventricular aneurysm in nine, tricuspid valve repair in three, aortic valve repair or replacement in four, and aortocoronary bypass in 44 patients. Twenty-six clinical, hemodynamic, angiographic, and operative variables were analyzed for statistical significance (univariate analysis) and then entered into a logistic regression analysis with operative and late mortality as end points. There were four operative deaths (8%). Only preoperative cardiogenic shock and mitral valve replacement with complete excision of the native valve were predictive of operative mortality. Actuarial survival at 4 years was 89 +/- 9% for patients with preserved chordae tendineae and 59 +/- 11% for patients with completely excised mitral valves. Only complete excision of the mitral valve and ejection fraction lower than 35% were predictive of late mortality. These data suggest that, although the papillary muscles are diseased in patients with mitral regurgitation secondary to myocardial infarction, it is important to preserve them and their chordae tendineae during mitral valve replacement.

Adult↗
PubMed1985

Induction of cell-cell adhesion by monovalent antibodies in a germ cell culture.

Four monoclonal antibodies, XT-I, MT-23, MT-24 and MT-29, that bind the XT-1-differentiation-antigen of male germ cells have been used to investigate the biological role of the XT-1-molecule of germ cells in short-term primary culture. Cultures from 10 days postpartum mice demonstrate increasing numbers of antigen-positive germ cells and increased antigen expression per cell with succeeding days of culture. Treatment of the antigen-positive cultures with three of the monoclonal antibodies, XT-I, MT-23 and MT-24, increases germ cell-germ cell adhesion in a dose-dependent fashion. Treatment with the fourth monoclonal antibody, MT-29, does not induce cell adhesion. The monovalent, Fab fragment of XT-I-antibody also elicits tight cell adhesion, thus ruling out antibody cross linking of molecules or cells. Saturating or near saturating amounts of the positive antibodies are required to produce adhesion, a result consistent with perturbation of a function that is performed by the sum of action of many of the XT-1-molecules on the cell. The ability of germ cells to undergo antibody-elicited tight adhesion is dependent on germ cell age and/or XT-1-antigen concentration. We hypothesize that the XT-1-molecule is involved in regulation of cell adhesion, an event which must occur in normal development.

Animals↗
PubMed1984

Arachidonate metabolism during chondrogenesis in vitro.

Chick embryo limb bud mesenchyme cells undergoing chondrogenesis in vitro were labeled with [3H] arachidonic acid and [14C] palmitic acid, and stimulated by mechanical means to convert a portion of their incorporated [3H] to radiolabeled compounds which co-chromatographed with authentic prostaglandins in the appropriate thin layer chromatography system. Chondrogenesis was (1) inhibited by concentrations of indomethacin or eicosa-5,8,11,14-tetraynoic acid which inhibited conversion of [3H] to prostaglandinlike compounds; and (2) stimulated by prostaglandin E2. We interpret these data to mean that (1) cells undergoing chondrogenesis in vitro are able to metabolize endogenous arachidonic acid to prostaglandins, and (2) synthesis of prostaglandinlike compounds is requisite to chondrogenesis in vitro.

Animals↗
PubMed1982

Cyclic nucleotides during chondrogenesis: concentration and distribution in vivo and in vitro.

This study correlates endogenous levels of cAMP and cGMP with their immunohistochemical localization during chondrogenic differentiation of C57B1/6J mouse limb mesenchyme in vivo and in vitro. A transient decrease in cGMP but not cAMP was found from days 12 to 13 in vivo correlating with early stages of chondrogenesis in the developing limb. Intracellular levels of both cAMP and cGMP in high density limb mesenchyme cultures increased 25% after 24 hr in culture when aggregate and nodule formation was detectable. When cells were seeded at different initial plating densities to delay the onset of aggregate and nodule formation, increased levels of intracellular cAMP correlated temporally with the appearance of nodules. Both cyclic AMP and cGMP were immunohistochemically localized in perichondrial cells and chondrocytes in vivo and in vitro. Therefore, (1) cAMP levels correlated temporally with the appearance of chondrogenic cells and (2) cAMP and cGMP were immunohistochemically localized to chondrogenic cells. These data indicate that fluctuations of both cAMP and cGMP levels may be involved in limb cartilage differentiation. Although increases in both nucleotides were found to correlate with the onset of chondrogenesis in vitro, in vivo data suggest that the amount of cAMP relative to cGMP rather than the absolute amount of an individual cyclic nucleotide may be more significant in modulating differentiation.

Animals↗
PubMedDate not supplied

Rapid detection of hog cholera virus in tissues by the polymerase chain reaction.

A rapid method for the detection of hog cholera virus (HCV) in infected tissues, using polymerase chain reaction (PCR) was developed. Total RNA isolated from HCV-infected tissues was reverse transcribed with AMV reverse transcriptase and the resulting complementary DNA was amplified by Taq DNA polymerase in the presence of two HCV-specific primers. The amplified DNA fragment was detected by agarose gel electrophoresis. The sensitivity of this method was at 10(4) TCID50 of HCV. The sensitivity increased approximately 1000-fold when the DNA was reamplified with a set of nested primers. DNA sequencing analysis of the PCR products revealed that the HCV sequence amplified from a local field isolate was highly homologous to the HCV Alfort strain. This method may be useful for pathological and epidemiological studies of HCV in pigs.

Animals↗