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Biomedical subjects

C Zhang

Publications and source records attributed to C Zhang.

At least 739 records · Page 41Linked to original sources
PubMed1991

Fetal tissue grafts for cerebellar atrophy.

It has been shown in a rat model that surgical injury to the right cerebellum with resultant ataxia can be corrected by implantation of embryonic cerebellar tissue into the injured cerebellum. Histological examinations of the cerebellar tissue revealed that mitoses of Purkinje cells of the implanted group were increased substantially over the control group's. The surgically induced ataxia resolved more rapidly in the cerebellar implant group than the control group. Based on this experimental data, a similar technique was applied in 6 patients with severe hereditary cerebellar degenerative ataxia. The preliminary results in these 6 surgically implanted patients with heredity degenerative cerebellar disease show 2 with marked improvement, 3 with moderate improvement and 1 with improvement for 2 months followed by mild deterioration but still better than presurgery. We also studied immunological markers in the blood and CSF in an attempt to determine whether rejection of implanted tissue occurs.

Adult↗
PubMed1990

Thermal denaturation of the Ca2(+)-ATPase of sarcoplasmic reticulum reveals two thermodynamically independent domains.

Inactivation of Ca2+ uptake and ATPase activity of the Ca2(+)-ATPase of rabbit sarcoplasmic reticulum was measured and compared to the thermal denaturation of the enzyme as measured by differential scanning calorimetry (DSC) and fluorescence spectroscopy. Two fluorophores were monitored: intrinsic tryptophan (localized in the transmembrane region) and fluorescein isothiocyanate (FITC)-labeled Lys-515 (located in the nucleotide binding domain). Inactivation, defined as loss of activity, and denaturation, defined as conformational unfolding, were irreversible under the conditions used. Activation energies (EA) and frequency factors (A) for inactivation were obtained for the enzyme in 1 mM EGTA and 1 mM Ca2+. These were transformed to a transition temperature for inactivation, Tm (defined as the temperature of half-inactivation when temperature is scanned upward at 1 degree C/min). All denaturation profiles were fit with an irreversible model to obtain EA and Tm for each transition, and the values of these parameters for denaturation were compared to the values for inactivation. In EGTA, denaturation obeys a single-step model (Tm = 49 degrees C), but a two-step model is required to fit the DSC provile of the enzyme in 1 mM Ca2+. The specific locations of tryptophan and the fluorescein label were used to demonstrate that denaturation in Ca2+ occurs through two distinct thermodynamic domains. Domain I (Tm = 50 degrees C) consists of the nucleotide binding region and most likely the phosphorylation and transduction regions [MacLennan, D. H., Brandl, C. J., Korczak, B., & Green, N. M. (1985) Nature 316, 696-700].(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effect of precursors on the synthesis of catecholamines and on neurotransmission in the superior cervical ganglion of the rat.

Male Sprague-Dawley rats (325-350 g) were anesthetized with urethane (1.5 g/kg i.p.) and treated with physiological saline, Aspartame (APM; 552 mumols/kg), or tyrosine (Tyr; 552 mumols/kg). Ganglionic transmission and the synthesis of dopamine (DA) and norepinephrine (NE) were measured in the superior cervical ganglion (SCG) following electrical stimulation of the cervical sympathetic trunk (CST). When the CST was stimulated with single pulses, neither APM nor Tyr affected the synthesis of NE or DA. However, in response to low- (5 Hz, 20 s) and high- (20 Hz, 20 s) frequency pulses, the metabolism of DA was increased (p less than 0.05), but to the same extent after saline, APM, or Tyr. In rats stimulated with similar low- and high-frequency pulses, the synthesis of NE was increased significantly (p less than 0.05) after Tyr, but not after APM or saline. In saline-treated controls, ganglionic transmission was not changed in response to single pulses, or low- or high-frequency stimulation. However, after treatment with APM, ganglionic transmission was depressed significantly (p less than 0.01) in response to high-frequency stimulation (single: 0.46 +/- 0.09 mV; low: 0.39 +/- 0.07 mV; high: 0.27 +/- 0.07 mV). After treatment with Tyr, ganglionic transmission was depressed significantly (p less than 0.05) in response to both low- and high-frequency stimulation (single: 0.44 +/- 0.04 mV; low: 0.22 +/- 0.12 mV; high: 0.26 +/- 0.07 mV). In the nonstimulated SCG, L-3,4-dihydroxy-phenylalanine (25 mg/kg) caused a rapid, significant (p less than 0.01) increase in the synthesis and metabolism of DA, but not of NE.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

[Dissolvable supporting in small artery anastomosis: an experimental study].

Intra-lumen supporting, made of biomaterial, non-toxic, tissue-compatible, and dissolvable, was used in anastomosing femoral artery on one side of 51 rabbits, while that on other side was anastomosed by conventional procedure for comparison. Results showed that suturing on the experiment group could be accomplished with better accuracy, less trauma and avoidance of puncturing the opposite wall, and with higher speed, shorter operation time than the contra. Better still, the intra-lumen supporting stabilized the vessel stumps and dilated the segments being handling, so that torsion and spasm were prevented. The intra-lumen supporting was then dissolved and no thrombosis developed in any of the experiment ones but some of the contra. Histological observation revealed that repair of tissue in each layer of the artery wall at the anastomosis site proceeded much quicker in the experiment ones than in the contra. We are impressed, through this survey, that the newly formed endothelial cells cover in the juncture area may arise from the uninjured endothelium nearby, and may also come from monocytes in the circulation.

Anastomosis, Surgical↗
PubMed1990

[Electroretinogram of normal rabbits (experimental research)].

Electroretinograms of 44 eyes (22 normal rabbits) were studied. Of them, 11 were albinotic and 11 colored. The highest amplitude of the a-wave was 87.90 +/- 22.70 microV. No statistically significant difference was found between the two groups. The highest amplitude of the b-wave was 241.4 +/- 43 microV in the albinotic and 220.06 +/- 26.9 microV in the colored rabbits (P less than 0.01). In each group of the rabbits, the b-wave amplitude increased when the flash intensity increased both in dark-adapted ERG and in light-adapted ERG.

Animals↗
PubMed1990

[Function of large plasmids of the plague pathogen].

Function of the largest plasmid of Yersinia pestis was studied. Assay of four strains of highly virulent Y. pestis isolated from different natural sources demonstrated that the characters of endotoxin production, sugar and alcohol fermentation, nitrate reduction as well as requirement in nutrients are mediated by no Y. pestis plasmids. On the contrary, FI and FII antigens are determined by the largest plasmid in some strains and are chromosome-mediated in others. It may well be that the genes for these antigens are comprised within the transposon-like DNA fragment.

Alcohols↗
PubMed1990

[Immunomodulatory action of the total saponin of Gynostemma pentaphylla].

The specimen of the total saponin for this experimental study was extracted from Gynostemma pentaphylla growing in Suining county in Hunan province. Weight of immune organs, content of anti-SRBC hemolysin, rate of special Ea-RFC formation and percentage of NK cell activity had been employed for the study as experimental indices, both the normal healthy mice and the mice with immunity impairment due to Cyclophosphamide (Cy) management as experimental models. The results of the study exhibited: (1) The total saponin of Gynostemma pentaphylla could markedly act against the immunity inhibition due to Cy management in the experimental animals, showing a variant recovery in mice treated by Cy in weight of the immune organs, content of hemolysin, forming rate of Ea-RFC and unequivocally elevating NK cell activity, by significant difference in comparison with the Cy control groups (P less than 0.05-0.01). (2) The total saponin showed a definite of bidirective immunomodulatory action in normal healthy mice, recovering the immune indices to normal value from either originally lower or higher than the medium figure, by significant difference in comparison with the Cy control groups (P less than 0.05-0.01). (3) The total saponin had actions to prevent from fatigue and to tolerate hypoxia under usual atmospheric pressure. The above description indicates that the total saponin of Gynostemma pentaphylla is a better immunomodulator, seems to be like the actions of some Chinese drugs, for example, Panax ginseng, Astragalus membranaceus etc.

Adjuvants, Immunologic↗
PubMed1989

Differentiation of avian adenovirus type-II strains by restriction endonuclease fingerprinting.

Three serologically indistinguishable viruses from the avian adenovirus type-II splenomegaly virus of chickens, marble spleen disease virus of pheasants, and hemorrhagic enteritis virus of turkeys, were analyzed by restriction endonuclease fingerprinting. The DNA from these viruses were examined with 6 restriction endonucleases (Bgl II, EcoRI, HindIII, Hha I, Xho I, and BamHI). Markedly different DNA cleavage patterns were found in these virus isolates with all the 5 enzymes, except with BamHI, suggesting genetic differences between isolates of adenovirus type II. Restriction endonuclease analyses were found to provide a method for distinguishing genetically different, and yet serologically similar, strains of avian adenovirus type II.

Adenoviridae↗