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C Gong

Publications and source records attributed to C Gong.

53 records · Page 3Linked to original sources
PubMed1994

What is the most accurate way to study the active properties of bladder smooth muscle?

There is often disagreement over the optimal method by which to study the active properties of smooth muscle. While some favor setting smooth muscle strips at a resting or passive tension of 1 g, others have argued in favor of determining the Lo or optimal length for maximal force generation for each individual strip. Setting each strip to its individual Lo is tedious, especially if one is dealing with multiple strips during one experiment. Is it possible to study smooth muscle strips at an average length at which most strips of similar dimensions exhibit their maximal force, and if this method is used to what extent does it underestimate the maximal force generated? When comparing bladder, smooth muscle strips 1 cm long from pregnant versus virginal rabbits, the average length at which maximal force was generated was 2.41 and 2.45 cm, respectively (p = n.s.). Studying all strips at a length of 2.5 cm (2.5 x the slack length) would have resulted in a 10% underestimate of the maximal force within each group (p = n.s.). We conclude that comparative bladder smooth muscle strip studies can be accurately carried out at an average fixed length provided that preliminary studies are done to determine the length-tension relationships for the specific experimental situation.

Animals↗
PubMed1993

Metabolic studies on rabbit bladder smooth muscle and mucosa.

Recent studies indicate that the mucosa of the urinary bladder may play a major role in the maintenance of normal bladder function. The mucosal surface of the urinary bladder serves as a protective layer against the irritative solutes found in the urine. The integrity of this barrier can be broken by overdistension, anoxia, detergents, alcohols, bacterial infection and by contact with agents to which the mucosa has been sensitized. In view that both anoxia and ischemia can mediate a breakdown in the role of the mucosal layer as a permeability barrier, it is reasonable to assume that this function is dependent on cellular metabolism. As an initial investigation we have compared a variety of biochemical and metabolic parameters between the mucosal layer (consisting of the lamina propria, urothelium, and any connective tissue and vascular tissue within this layer); and the muscularis layer. The results of these studies demonstrated that the rate of glucose metabolism to lactic acid (LA) of the mucosa was more than three-fold greater than that of the smooth muscle. The rate of CO2 production of the mucosa was 60% greater than that of the unstimulated smooth muscle. The maximal activity of the mitochondrial enzyme citrate synthase was significantly greater in the mucosa than in the smooth muscle, however, the activity of malate dehydrogenase was similar for both tissues. The maximal activity of the cytosolic enzyme creatine kinase was more than two-fold greater in the bladder smooth muscle than in the mucosa; although the affinities of the creatine kinase isoforms of the mucosa were significantly greater than those of the muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Molecular pathology of Alzheimer neurofibrillary degeneration.

The most characteristic brain lesion of Alzheimer disease is the accumulation of paired helical filaments (PHF) in the affected neurons. Based on solubility in detergents there are two general populations of PHF, the readily soluble (PHF I) and the sparingly soluble (PHF II) types. The major polypeptides of PHF are the microtubule associated protein tau. Tau in PHF is present in abnormally phosphorylated forms. In addition to the PHF, the abnormal tau is also present in unpolymerized form in the AD brain. Small amounts of ubiquitin (%) are associated with PHF II but neither with PHF I nor with the unpolymerized abnormally phosphorylated tau in AD brain. Furthermore, the pretangle neurons can readily be immunolabeled for abnormally phosphorylated tau but not for ubiquitin. The level of tau in neocortex is several-fold higher than in AD aged control cases, but this increase is in the form of the abnormally phosphorylated protein. The microtubule associated proteins from AD brain do not promote the assembly of microtubules in vitro, whereas the in vitro dephosphorylated PHF polypeptides stimulate the binding of GTP to the exchangeable site of tubulin and the assembly of microtubules. In vitro the phosphate groups in PHF are less accessible than those of tau to alkaline phosphatase. It is suggested that a defect in the protein phosphorylation/dephosphorylation system leads to hyperphosphory-lation of tau. The altered tau contributes to a microtubule assembly defect and consequently compromises the axoplasmic flow and leads to neuronal degeneration.

Alzheimer Disease↗
PubMed1992

[Establishment and characteristics of a lymphoblastoid cell line (CKM) resistant to 6-TG and ouabain].

Three lymphoblastoid cell lines (CKM-c, CKM-1 and CKM-8) have been established by EBV-transformation from cord blood. They have been maintained for 1 year after 120 passages with rapid growth. The population doubling times were 24.5h (CKM-1), 30 h (CKM-8) and 36 h (CKM-c). The B lymphocyte features were identified under an electron microscope. EBV antigens including EBNA, VCA-Ig A, MA and EA were negative in all the cell lines. The median chromosome number was 48-50. Interferon (IFN) was induced by NDV treatment of the CKM-c cell line. CKM-8 has been modified to be resistant to both thioguanine (30 micrograms/ml) and Ouabain (10(-5)) for the production of human-human hybridomas.

Cell Line, Transformed↗
PubMed1991

Establishment of human myeloma cell line KM-2R and its preliminary application to human-human hybridoma research.

The authors report the establishment of a human myeloma cell line--KM-2R--and its preliminary use in human-human hybridoma research. KM-2R cells are resistant to both 6-TG and ouabain. Their doubling time is about 30 h. They have a modal chromosome number of 81-85. Using ELISA and immunodiffusion techniques, gamma-heavy and kappa-light chains were detected in the concentrated cell culture supernatant. KM-2R cells are sensitive to HAT medium. When fusing with normal human spleen cells, tonsil cells, and B lymphoblasts transformed by EB virus, fusion frequencies of 20-60% resulted.

Cell Division↗
PubMedDate not supplied

Metabolic studies on the rabbit corpus cavernosum.

Erectile function (erection and detumescence) involves the complex interaction of direct neuronal stimulation of corporal smooth muscle, neurohumoral release of specific endothelial contractile and relaxant factors, and secondary modulation by a variety of putative neuropeptides and vasoactive modulators. The net result is a rapid and sustained relaxation of the smooth muscle elements during erection and contraction of the smooth muscle during detumescence. Proper function of the corporal tissue is dependent upon cellular metabolism of glucose and the generation of cellular energy in the form of high energy phosphates. The current study characterizes the following metabolic parameters of the rabbit corpus cavernosum: Tissue concentrations of creatine phosphate (CP), ATP, ADP, and AMP; maximal rate of glucose metabolism to lactic acid and CO2; and activities of the enzymes creatine kinase (CK), citrate synthase, and malate dehydrogenase. For comparative purposes only, bladder smooth muscle preparations were analyzed simultaneously with and under the same conditions as the corpus cavernosum. The results are as follows: The concentrations of ATP and CP in the corpora were significantly lower than the concentrations in bladder. In the corpora, the tissue concentration of CP was lower than the tissue concentration of ATP, whereas the concentration of CP in the bladder was higher than the concentration of ATP. The rate of glucose metabolism to lactic acid and to carbon dioxide was similar for both bladder smooth muscle and corpus cavernosum. The maximal enzymatic activity of the mitochondrial enzyme citrate synthase was similar for both tissues; similarly, there was no significant difference in the activity of malate dehydrogenase between the two tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗