Biomedical subjects
G Z Chen
Publications and source records attributed to G Z Chen.
Peripheral neovascularization of muscle and musculocutaneous flaps in the pig.
Late loss of free muscle flaps following surgical or accidental trauma to the dominant vascular pedicle has been reported. In this study, time-dependent ligation of the dominant vascular pedicle was undertaken in denervated latissimus dorsi musculocutaneous or muscle-only island flaps in the pig. Muscle flaps were covered with a skin graft, and silicon rubber sheets were inserted between the flaps and their bases to simulate a poorly vascularized bed. Hemodynamic and viability studies were then performed using intravenous fluorescein (skin viability), tetrazolium blue (muscle viability), and radiolabeled 15-micron microspheres (capillary blood flow). Blood flow did not change in acutely raised musculocutaneous flaps (n = 10) but was significantly elevated in acutely raised muscle-only flaps (n = 10), suggesting that the skin paddle may steal blood flow from the underlying muscle in musculocutaneous flaps. Peripheral neovascularization at 1 day to 8 weeks was assessed (n = 30). Viability increased during the first week of revascularization and was not different in musculocutaneous and muscle-only flaps. Revascularization of muscle-only flaps was enhanced compared with musculocutaneous flaps in the 2- to 8-week period.
[Synchronous spectrofluorimetry for simultaneous determination of riboflavin and pyridoxine and its application in multivitamin preparations].
A new method for the simultaneous determination of riboflavin and pyridoxine by synchronous spectrofluorimetry is described. The measurement was carried out in a buffer solution of pH 7 with delta lambda = 58 nm for synchronous scanning. Under the experimental conditions two peaks appeared at 526 nm and 389 nm in the obtained synchronous fluorescence spectrum, corresponding to riboflavin and pyridoxine, respectively. This method was proved to be simple and specific. The fluorescence relative intensity is linearly related with concentration over the range of 0-1 microgram/ml and 0-1.5 micrograms/ml for riboflavin and pyridoxine, respectively. The detection limit was 0.5 ng/ml for riboflavin and 1 ng/ml for pyridoxine. The relative errors of the measurements were less than 5% for artificial samples. The proposed method has been applied to the analyses of riboflavin and pyridoxine in three kinds of commercial multivitamin preparations. The obtained synchronous spectra of multivitamin preparations coincided with those of the mixed standard solution of riboflavin and pyridoxine. Recoveries of 93.5-105.7% were obtained.
Effects of cordyceps sinensis on natural killer activity and colony formation of B16 melanoma.
This paper reports the study on the effects of the ethanol extract of Cordyceps sinensis (CS-II), a potent herbal tonic, on murine and human in vitro natural killer cell (NK) activities and on murine in vivo NK activity (by 125I clearance assay), and on colony formation of B16 melanoma in mouse lungs. The results revealed that: 1. the in vivo and in vitro NK activities of mouse were both significantly augmented by intraperitoneal (ip) injection of CS-II. Besides, the inhibition of mouse NK activity by cyclophosphamide (Cy) was prevented following the administration of CS-II; 2. the in vitro NK activity of human peripheral blood mononuclear cells (PBMs) was elevated by preincubation of PBMs with CS-II; and 3. the colony formation of B16 melanoma in mouse lungs was reduced significantly by ip pretreatment of the mice with CS-II. This study indicates that CS-II may be used as an immunopotentiating agent in treating cancer and immunodeficient patients.
Purification and characterization of 3-hydroxymethylglutaryl-coenzyme A reductase of Schistosoma mansoni: regulation of parasite enzyme activity differs from mammalian host.
The enzyme 3-hydroxymethylglutaryl-CoA (HMG-CoA) reductase plays a critical role in regulating the production of cholesterol, dolichols, and ubiquinones in mammals. The inhibition of this enzyme in Schistosoma mansoni is accompanied by a cessation of egg production by the female parasite and a reduced ability of the parasite to properly glycoslyate their proteins. Furthermore, we recently demonstrated that mevinolin, if given continuously over a period of 10-14 days, is a potent antischistosomal drug. In this paper, we describe the properties of purified HMG-CoA reductase from S. mansoni. Using affinity chromatography, we were able to obtain a 417-fold purification of the enzyme which had Km values similar to the rat enzyme for HMG-CoA and NADPH. The Ki value for mevinolin, a potent and selective inhibitor of the rat reductase (Ki = 0.6 nM), was significantly higher (Ki = 46 nM) for the schistosome enzyme. SDS-PAGE and HPLC of the purified enzyme resulted in the appearance of a single protein, which had a molecular weight (66,000) in the range reported for the rat enzyme. Parasite reductase activity, unlike that of its host, did not display a circadian rhythm. Furthermore, agents which elevate (cholestyramine) or decrease (cholesterol) mammalian reductase activity had no effect on the parasite enzyme. Our results suggest that the mechanism which regulates production of the parasite's enzyme may differ from its mammalian host.
[Effect of xiao banxia-fuling decoction on the amplitude of gastric electrical spike wave in rats after irradiation of the gastric region].
The effect of xiao banxia-fuling decoction on the amplitude of gastric electrical spike wave in rats after irradiation of the gastric region was investigated in this study. The result proved: by using the medicine every day, the amplitude of spike wave, which was reduced by irradiation, was significantly raised at the 10th, 14th day in the corpus and 7th, 10th, 14th, 21st day in the antrum after 15Gy irradiation (P less than 0.01). Since the altitude of spike wave correlated with the intensity of the gastric motility. The authors believe that this compound Chinese herbs may have some beneficial effects on preventing the inhibition of gastric motility and reducing the radiation reaction of digestive system.
Effects of Cordyceps sinensis on murine T lymphocyte subsets.
It was shown by flow cytometry analysis that crystalized preparation of Cordyceps sinensis (Cs-Cr) caused significant elevation of the number of T helper cells and Lyt-1/Lyt-2 (T helper to T suppressor cell) ratio both in peripheral blood and the treated mice spleen. The spleen weight, phagocyte counts and phagocytic activity were also elevated in the treated group. In addition, Cs-Cr could protect T helper cells from the immunosuppressive effects of prednisolone acetate and cyclophosphamide. These results further substantiate the fact that Cs-Cr is an immunoregulator/biological response modifier of cellular immunity and may be potentially useful in handling immunodeficient or immunosuppressed patients.
Antischistosomal action of mevinolin: evidence that 3-hydroxy-methylglutaryl-coenzyme a reductase activity in Schistosoma mansoni is vital for parasite survival.
The enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA reductase) plays an important role in regulating egg production in the human parasitic trematode Schistosoma mansoni. Infected mice treated with a low dose of mevinolin, an inhibitor of this enzyme, stopped egg production by the parasite and blocked the pathology associated with the infection. As an extension of this work, we exposed adult and developing schistosomes to higher doses of mevinolin for an extended period of time and observed the following: administration of 0.2% mevinolin in the diet of infected mice for 14 days resulted in 96-100% elimination of adult parasites. Administration of the same dose for 2 days before, and for 15 days after infection, resulted in 93-96% reduction of adult parasites. Co-administration of mevinolin with 0.5% mevalonate, but not 0.5% cholesterol, blocked the antischistosomal activity of mevinolin. We monitored schistosomal and mouse liver HMG-CoA reductase activity during the course of treatment and observed that HMG-CoA reductase activity was elevated in the liver but significantly reduced in the parasite. In vitro incubation of paired schistosomes with mevinolin, for up to 11 days, resulted in a dose- and time-dependent reduction of parasite motility and lactate production with eventual death. These in vitro effects were no evident when mevalonate was added to the culture system in place of, or in addition to, mevinolin. Collectively, the evidence suggests that mevalonate and/or metabolite not only plays a vital role in schistosome egg production, but is vital for survival of the parasite.
Capillary cloning of primary human tumor cells: assay miniaturization for drug efficacy testing.
The conventional double-layer agar method of cloning human tumor cells requires a substantial number of viable tumor cells and 14-21 days of culture. These prerequisites frequently limit its utility as an assay. In an attempt to circumvent these limitations and to reduce the amount of drug that is needed in the assay, we have further developed and miniaturized the assay in which human tumor cells are cloned in glass microcapillary tubes. Cultures consisted of 50 microliters containing 15,000 nucleated cells in 975 mm capillary tubes which were incubated for seven days. The results from 50 consecutive tumor biopsies resulted in cloning efficiencies, ranging from 0.007% to 1.0% with an overall successful cloning of 88% of all tumors tested and a good linear growth relationship and chemotherapy sensitivity. This miniaturized assay offers distinct advantages for drug efficacy testing including high cloning efficiencies, small tumor sample and drug requirements, quicker assay turnaround time and a general conservancy of reagents and incubator space.
Glutamine- vs glucose-supported motor activity in Schistosoma mansoni: physiological relevance of aerobic metabolism.
The ability of Schistosoma mansoni to generate energy through aerobic metabolic processes was examined in adult parasites in vitro. Parasite catabolism of radiolabeled glucose, glutamine, and other amino acids to CO2 and Krebs cycle intermediates was measured under a variety of incubation conditions. L-Glutamine was metabolized to CO2 via the intermediates glutamate, alpha-ketoglutaramate, and alpha-ketoglutarate in worms incubated in a balanced salts solution containing this amino acid as the only organic constituent. Of the other amino acids tested, CO2 production was detected from L-glutamate and L-asparagine. The catabolism of L-glutamine to CO2 was reduced by the respiratory inhibitor antimycin A. The motility of schistosomes in culture was maintained for at least 24 hr when L-glutamine was the only carbon source available to the worms. Under these conditions, motility was reduced when parasites were exposed to a respiratory inhibitor such as KCN, antimycin A, rotenone, or oligomycin, but it was completely restored by the addition of glucose to the medium. These results suggest that while the schistosome is capable of limited aerobic energy-generating processes under certain conditions, survival is not contingent upon these processes in the presence of glucose.
Physiological role of HMG-CoA reductase in regulating egg production by Schistosoma mansoni.
Pathological lesions observed in humans infected with Schistosoma mansoni are due to the eggs produced by the female parasite. Mevinolin, a potent inhibitor of the enzyme hydroxymethylglutaryl-CoA (HMG-CoA) reductase, blocks egg production by this parasite. In this report, we demonstrate that cholesterol precursors, mevalonate and farnesol, stimulate egg production by the female parasite and that these precursors can reverse the mevinolin-induced inhibition of egg production. Because the parasite cannot synthesize cholesterol, we incubated parasites in a culture media containing radiolabeled acetate with and without mevinolin. We isolated nonsterol lipids from the parasite and observed that mevinolin dramatically reduced the conversion of acetate into the polyisoprenoid (dolichols) lipids of the parasite. Dolichols and other nonsterol lipids did not stimulate egg production. HMG-CoA reductase activity was observed in homogenates of the parasite and was inhibited by mevinolin (Ki = 52 nM), but its activity was tripled when the parasite was chronically exposed to low doses of the drug. Parasites with increased reductase activity produced five to six times more eggs. Lastly, chronic administration of large doses of mevinolin to infected mice resulted in a marked reduction of the pathology associated with the infection. These results suggest that egg production in S. mansoni is associated with the parasite's HMG-CoA reductase activity and that a nonsterol lipid produced in the biochemical pathway regulated by this enzyme stimulates egg production.
Schistosoma mansoni: measurement of Na+ ion activity in the tegument and the extracellular spaces using ion-selective microelectrodes.
Ion-selective microelectrodes were used to measure sodium ion activity (aNa) in the tegument and interstitial spaces in adult male Schistosoma mansoni. In RPMI 1640, aNa averaged 31 +/- 13 mM in the tegument, a value significantly less than that in the bathing medium. In the interstitial spaces, it averaged 72 +/- 17 mM, a value nearly the same as that in the bathing medium. In hypo- or hyperosmotic media, aNa in the interstitial spaces varied by a value commensurate with change in aNa in the medium, but aNa in the tegument was changed by only a small amount. Monensin (10 microM), low temperature (20 C), and ouabain (0.3 to 10 microM) all caused significant increases in aNa in the tegument. Hypo- and hyperosmotic media produced initial weight changes followed by gradual recovery back toward original weights. It is concluded that the schistosome is a volume regulating osmoconformer with osmolality of the extracellular fluid approximating that of the bathing medium, but that within the tegument of the parasite, Na+ concentration is controlled by active transport processes.
Diagnosis and treatment of congenital choledochal cyst (report of 40 cases).
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Calmodulin: biochemical, physiological, and morphological effects on Schistosoma mansoni.
Results of radioimmunoassays for the Ca2+-binding protein, calmodulin, revealed that this receptor constitutes 0.53 +/- 0.12% of the total protein in adult male Schistosoma mansoni. Schistosome calmodulin purified by Ca2+-dependent hydrophobic interaction chromatography showed an apparent molecular weight of 19 kDa, and its mobility on sodium dodecyl sulfate polyacrylamide gels was influenced by the presence of Ca2+ but not the antischistosomal drug praziquantel. Calmodulin from the parasite effected a four-fold stimulation of bovine heart adenosine 3',5'-cyclic monophosphate phosphodiesterase; this process was inhibited by removal of Ca2+ with ethyleneglycol-bis(B-aminoethylether)-N,N'-tetraacetic acid but not by praziquantel. Inhibition of calmodulin-activated processes with antipsychotic compounds in vitro resulted in a number of time- and concentration-dependent changes, including inhibition of schistosome calmodulin stimulation of bovine heart phosphodiesterase, disruption and depolarization of the parasite's tegument, and positive inotropic effects on longitudinal musculature. Results of this study indicate that calmodulin is a functional component of schistosomes and suggest that the role it serves is analogous to that obtained in other eukaryotes; i.e., it is an important component of numerous processes regulated, in part, by Ca2+.
Schistosomiasis control in hilly regions of Fujian Province.
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Total reconstruction of the ear with auditory function: a two stage procedure.
The rational treatment of severe microtia or anotia should be to restore not only the form but also the auditory function of the ear. To achieve this aim it is obvious that plastic surgeons must co-operate closely with an otologist: yet this degree of co-operation is seldom seen. This paper describes a two-stage procedure for total ear reconstruction with auditory function. In stage I, a tympanoplasty is performed before transplantation of the carved cartilage framework. Stage II consists of elevation of the reconstructed auricle and transplantation of a full-thickness skin graft to the post-auricular defect. Certain modifications of the operative techniques that we have found useful are discussed in detail.
[Antithrombin activity and platelet aggregation by acid mucopolysaccharides isolated from Stichopus japonicus Selenka].
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[The nature of the symptom-complex "stagnancy of the liver and function deficiency of the spleen"].
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