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Biomedical subjects

H H Chou

Publications and source records attributed to H H Chou.

51 records · Page 3Linked to original sources
PubMed1995

Laparoscopic repair of bowel herniation through previous cannula insertion sites.

Operative laparoscopy frequently requires large cannulas below or above the umbilicus, which may result in unusual complications such as small bowel herniation through these insertion sites. Three women experienced small bowel herniation through cannula incision sites, either extraumbilically or paraumbilically, after major laparoscopic surgery. Two patients who had undergone laparoscopic myomectomy developed small bowel herniation through the 12-mm extraumbilical cannula site on postoperative days 7 and 8, respectively. In the first woman, the nontender, palpable, and reducible herniation healed spontaneously, with no episode of herniation during follow-up. The second patient required laparoscopic reduction of the herniated loop and repair of the fascial defect. The last woman had undergone laparoscopic-assisted vaginal hysterectomy and developed small bowel herniation through an unrecognized fascial defect paraumbilically 3 days postoperatively. Intended repair by laparoscopy was changed to laparotomy due to extensive and incarcerated bowel herniation.

Abdominal Muscles↗
PubMed1995

Extraumbilical insertion of the operative laparoscope in patients with extensive intraabdominal adhesions.

In 12 patients who had known or suspected intraabdominal adhesions, we evaluated the benefit of using Palmer's point for inserting the Veress needle and primary cannula during laparoscopic adhesiolysis to prevent direct intestinal injury. After inserting the laparoscope through this point, four women were found to have extreme intestinal adhesions around the umbilical area, and intestinal or severe omental injury might occur if the cannulas were inserted directly through the umbilical fossa. The other eight patients had omentum, partial to severe, adherent to the anterior abdominal wall. No complication occurred during insertion of the Veress needle and primary cannula through Palmer's point. Nine patients had successful laparoscopic adhesiolysis and were discharged within 2 days. In the other three women the procedure was converted to laparotomy because of extensive intestinal adhesions (2 patients) and small bowel injury during laparoscopic adhesiolysis (1). Palmer's point can be considered a safe and good alternative site for inserting the Veress needle and primary cannula to lyse dense intestinal and extensive omental adhesions. This technique should provide the surgeon with wider visual angel and surgical field, thus making adhesiolysis much easier to perform.

Abdomen↗
PubMed1995

Methanol oxidation mutants in Methylobacterium extorquens AM1: identification of new genetic complementation groups.

Two-hundred-and-eight new Methylobacterium extorquens AM1 methanol oxidation (Mox) mutants were isolated and placed into complementation groups. Complementation analyses identified new Mox groups in the Mxb and Mxc loci and at a new locus, Mxd. Thirty-seven mutants at the Mxb locus were divided into MxbM and MxbD complementation groups on the basis of their complementation pattern. Twenty-nine mutants at the Mxc locus fell into three complementation groups, MxcB, MxcQ and MxcE. The direction of transcription for genes at this locus could be inferred from the subclones. Eighteen of the new mutants were not complemented by previously isolated M. extorquens AM1 clones but were complemented by two new overlapping clones. This locus was called Mxd and the mutants fell into two complementation groups, MxdR and MxdS. Immunoblots from all these mutant classes showed that all of the Mxb and Mxc strains had substantially reduced levels of MxaF (large subunit of methanol dehydrogenase) and cytochrome cL, compared to the wild-type. These mutants, particularly the Mxb mutants, also had elevated levels of cytochrome c-553. These results are consistent with a role for the MxbMD and MxcBQE complementation groups in the regulation of expression of mxaF. The MxdR and MxdS mutants had normal levels of MxaF and both c-type cytochromes.

Genes, Bacterial↗
PubMed1995

Cloning and expression of an antigenic domain of glycoprotein gE of pseudorabies virus in Escherichia coli and its use as antigen in diagnostic assays.

Use of a combination of an effective gE gene-deleted pseudorabies virus (PRV) vaccine with a companion diagnostic kit for PRV glycoprotein gE has proven successful in several pseudorabies-eradication programs. To produce a large quantity of functional gE protein for development of a PRV-gE diagnostic kit, an Escherichia coli expression system containing the distal region of the PRV-gE gene of a PRV strain CF was constructed. The expressed protein contained 134 amino acids of gE protein (amino acids 77-210) fused to a 19-amino acids tag containing 6 histidine residues. After induction, a truncated PRV-gE polypeptide of 18-kd was expressed to about 20% of the total E coli proteins. Results of immunoblot analysis indicated that this E coli-produced PRV-gE protein reacted specifically with serum from PRV-hyperimmunized pigs and from field PRV-infected pigs, but not with serum samples from specific-pathogen-free pigs or pigs inoculated with gE-deleted PRV vaccine. These data indicate that, although the recombinant gE protein is produced in E coli, it still retains the antigenicity of the viral gE glycoprotein. Comparison between the recombinant gE protein, using immunoblot analysis with a commercial gE ELISA containing natural PRV-gE protein, revealed comparable test performance. This finding indicated that recombinant gE protein produced by E coli can be used for development of a companion serologic assay for a PRV-gE gene-deleted vaccine.

Animals↗
PubMed1994

Characterization of mullerian inhibiting substance binding on cervical carcinoma cells demonstrated by immunocytochemistry.

Müllerian inhibiting substance (MIS) is a glycoprotein released from Sertoli cells or follicular cells of gonads, responsible for the regression of Müllerian ducts and/or Müllerian-derived tumor cells. Binding of MIS to target cells is essential for initiating regression. A human cervical carcinoma CaSki cell was examined by quantitative immunocytochemistry detected by anti-avian MIS antibody for MIS binding ability. Various treatments of WGA-peroxidase conjugate, enzyme digestion, sodium periodate or exogenous estrogen before antibody recognition were performed. It was found that the WGA partially blocked MIS binding to CaSki cell surfaces. Protease digestion of CaSki cell surfaces prior to addition of MIS or an anticervical carcinoma monoclonal antibody 1H10 (MAb 1H10), blocked the binding of MIS but not MAb 1H10 to cell surfaces. Sodium periodate and overnight exposure of CaSki cells to estrogen or diethylstilbestrol before or after fixation of the cells, did not influence MIS binding ability in vitro. MIS binding was higher on avian Müllerian duct compared with MIS binding to CaSki cells by quantitative immuno-gold labeling analysis. MAb 1H10 immuno-gold complexes binding to CaSki cells was also obtained and compared with MIS immuno-gold bindings. MIS binding site could be a polypeptide which survived sodium periodate treatment. The 'critical window' period, in which developing Müllerian ducts respond to exogenous estrogen protection from MIS regression, is possibly lost in CaSki cell.

Anti-Mullerian Hormone↗
PubMed1994

An extended cellular space method for simulating autocatalytic oligonucleotides.

Self-replicating nucleotides and other self-replicating molecules are an active area of study today by organic chemists. Such studies are important for improving our understanding of the origins of life. Computational studies of self-replicating molecules could increase our insight into their properties, but existing computational techniques have been limited in their usefulness for such reactions (numerical simulation of differential equations requires reaction rate constants that are difficult to obtain, cellular automata models are too restrictive for modeling molecular movements and bindings, etc.). We have thus developed an efficient modified cellular automata method that supports the study of self-replicating oligonucleotides. We explain this method and illustrate its use with a specific self-replicating (autocatalytic) deoxyribohexanucleotide.

Algorithms↗
PubMed1993

Ischemia-induced changes in alpha-tubulin and beta-actin mRNA in the gerbil brain and effects of bifemelane hydrochloride.

Using in situ hybridization histochemistry, we examined changes in the cytoskeletal protein alpha-tubulin and beta-actin mRNAs in the gerbil brain 14 days after transient ischemia. In an attempt to identify the changes induced in the synthesis of cytoskeletal protein by ischemia, we also evaluated the effects of post-ischemia administration of bifemelane on these cytoskeletal proteins. alpha-Tubulin and beta-actin mRNAs were decreased in the CA1 region 14 days after transient ischemia. These decreases coincided with the loss of CA1 pyramidal cells, suggesting that they may have been related to delayed neuronal death. The beta-actin mRNA level in ischemic controls was significantly increased in the dentate gyrus, habenular nucleus, and medial and lateral thalamic nuclei, where some afferent nerves project into the hippocampal pyramidal cells. The increased beta-actin mRNA suggests that there may be a compensatory enhancement of actin synthesis in the afferent neurons that restores loosened synaptic connections with the ischemic cells in the CA1-4 fields. Administration of bifemelane just after recirculation prevented most of the ischemia-induced mRNA reductions in the CA1 field. Bifemelane's effect may be related to inhibition of Ca2+ influx and its radical scavenging activity. When bifemelane was administered to the ischemic group, alpha-tubulin mRNA levels significantly increased in the dentate gyrus and amygdaloid nucleus, and beta-actin mRNAs showed a tendency to increase in the CA3 and CA4 fields, dentate gyrus, and medial and lateral thalamic nuclei. These findings suggest that bifemelane may enhance synthesis of cytoskeletal protein, especially in the ischemic brain, inducing axon outgrowth or synapse formation.

Actins↗
PubMed1993

Minimizing complexity in cellular automata models of self-replication.

Understanding self-replication from an information processing perspective is important because, among other things, it can shed light on molecular mechanisms of biological reproduction and on prebiotic chemical evolution. Intuition, biological knowledge, and early computational models of self-replication all suggested that self-replication is an inherently complex process. In this paper we describe recent computational studies that challenge this viewpoint. We summarize our recent work with cellular automata models of simple yet non-trivial self-replicating structures called unsheathed loops. For example, one unsheathed loop consists of only six components and requires only 20 rules to specify the local intercomponent interactions needed to bring about replication. The implication of this work is that, when viewed as an emergent property of numerous local, concurrent interactions between components, self-replicating systems can be substantially simpler than is generally recognized.

Computer Simulation↗
PubMed1992

Late onset and long-lasting suppressive effects of ceruletide, an analogue of cholecystokinin, on c-fos mRNA expression in the rat striatum.

C-fos mRNA expression by stimulation with subcutaneous (s.c.) administration of saline or cycloheximide (CHX) was examined in the rat striatum with or without pretreatment with ceruletide, an analogue of cholecystokinin. The c-fos mRNA induction 1 h after CHX stimulation (25 mg/kg, s.c.) was significantly suppressed by ceruletide pretreatment (80 micrograms/kg, s.c.) 2 h before CHX stimulation in the striatum, and tended to be suppressed by ceruletide pretreatment 4 h before saline or CHX stimulation. Long-lasting and inhibitory effects of ceruletide on dyskinesia and on dopaminergic (DAergic) neuronal systems, and c-fos mRNA expression by activation of the DAergic system have been reported. The present findings together with previous reports suggest that ceruletide might have late onset and long-lasting suppressive effects on the expression of c-fos mRNA in the striatum and that these effects might be related to its effects on DAergic neuronal transmission.

Animals↗
PubMed1989

Inhibition of DNA synthesis and cell division by a cell surface sialoglycopeptide.

We have isolated and purified a cell surface sialoglycopeptide (SGP) from bovine cerebral cortex cells that previously was shown to be a potent inhibitor of cellular protein synthesis. The following studies were carried out to characterize the potential ability of the SGP to inhibit DNA synthesis and to arrest cell division. Treatment of exponentially proliferating Swiss 3T3 cells with the SGP inhibitor resulted in a marked inhibition of thymidine incorporation within 24 h. When the SGP was removed from inhibited cultures, a sharp rise in 3H-thymidine incorporation followed within 3-4 h that peaked well above that measured in exponentially growing cultures, suggesting that the inhibitory action of the SGP was reversible and that a significant proportion of the arrested cells was synchronized in the mitotic cycle. In addition to DNA synthesis, the inhibitory action of the SGP was monitored by direct measurement of cell number. Consistent with the thymidine incorporation data, the SGP completely inhibited 3T3 cell division 20 h after its addition to exponentially growing cultures. Upon reversal there was a delay of 15 h before cell division resumed, when the arrested cells quickly doubled. Most, if not all, of the growth-arrested cells appeared to have been synchronized by the SGP. The SGP inhibited DNA synthesis in a surprisingly wide variety of target cells, and the relative degree of their sensitivity to the inhibitor was remarkably similar. Cells sensitive to the SGP ranged from vertebrate to invertebrate cells, fibroblast and epitheliallike cells, primary cells and established cell cultures, as well as a wide range of transformed cell lines.

Animals↗
PubMed1987

A unique sialoglycopeptide growth regulator that inhibits mitogenic activity of a phorbol ester tumor promoter.

The ability of a naturally occurring cell surface sialoglycopeptide growth inhibitor to antagonize the induction of DNA synthesis by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) was studied with mouse 3T3 cells. The bovine sialoglycopeptide was shown to be a potent antagonist of TPA-induced DNA synthesis in confluent 3T3 cell cultures. Kinetic studies demonstrated that inhibition of TPA-induced DNA synthesis required the addition of the sialoglycopeptide within 15 min of TPA treatment. Addition of the sialoglycopeptide 30 min or longer after the cells were exposed to TPA did not block stimulation of DNA synthesis by TPA. The inhibition of TPA action was shown not to be restricted to DNA synthesis in 3T3 cultured cells since the sialoglycopeptide also inhibited TPA-induced ornithine decarboxylase (ODC, L-ornithine carboxylase, EC 4.1.1.17) activation in suspensions of mouse epidermal and 3T3 cells.

Animals↗
PubMed1986

Purification and characterization of a bovine cerebral cortex cell surface sialoglycopeptide that inhibits cell proliferation and metabolism.

A sialoglycopeptide from bovine cerebral cortex cells was purified to apparent homogeneity by a procedure that included chloroform/methanol extraction, diethylaminoethyl ion exchange chromatography, wheat germ agglutinin affinity chromatography, size-exclusion HPLC, and hydrophobic interaction chromatography. The cell surface inhibitor had a molecular weight of approximately 18,000, no subunit composition was detectable on reduction and polyacrylamide gel electrophoresis analysis, and the glycopeptide apparently contained sialic acid, as illustrated by its ability to bind to Limulus polyhemus lectin. Deglycosylation of the molecule, however, did not reduce its protein synthesis inhibitory activity. As little as 20 ng of the sialoglycopeptide was capable of inhibiting protein synthesis in a wide variety of fibroblast cell lines but not in transformed cells. Mice immunized with the sialoglycopeptide produced antibodies that, when bound to protein A-agarose gel, removed the inhibitory activity from solution. The antibodies were used to identify a single isoelectric focused band and to establish the pI of 3.0 for the molecule.

Animals↗
PubMedDate not supplied

Effects of chronic codergocrine mesylate administration on the brain somatostatinergic system in aged rats.

Codergocrine mesylate (dihydroergotoxine; DHET), which is an ergot derivative, has been reported to counteract some age-induced impairments in brain function, but the mechanism of these effects is not known. We examined the effect of chronic DHET administration on the somatostatinergic system in the brains of aged rats. Intraperitoneal injections of DHET (1 mg/kg per day) or of vehicle were given to aged rats for 14 days, and resulted in a significant increase in somatostatin (SOM) receptor binding in all six brain regions examined except the hindbrain. DHET had no effect on SOM receptor binding in the brains of young-adult rats. However, the SOM concentration in aged rats was nearly identical to that in young-adult rats and the SOM concentration in different brain areas did not change after chronic administration of DHET. Thus, the present results suggest that chronic administration of DHET can ameliorate at least one of the age-induced impairments of brain somatostatinergic function.

Journal Article↗