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Biomedical subjects

Y F Zhang

Publications and source records attributed to Y F Zhang.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Surgical treatment of pituitary adenoma].

Seventy-four patients with pituitary adenoma were treated by surgery, including 51 transsphenoidal and 23 transcranial approaches, without death, postoperative leakage of CSF and early-period intracranial infection. Many patients had a transient diabetes insipidus after operation. In discussion we attended the difference of attacking age of pituitary adenoma between male and female, the significances of CT and MRI as well as the indication and the important points of various approaches.

Adenoma, Acidophil↗
PubMed1994

Effect of glucocorticoid receptor (GR) blockade on endotoxemia in rats.

To study the clinical significance of the decrease of glucocorticoid receptor (GR) in stress and shock, GR was blocked about 80% by mifepristone (RU38486), and the effects of the blockade on the pathological changes of endotoxemia were studied in rats. The results revealed that GR blockade may exacerbate the pathological and pathophysiological changes of endotoxemia: (1) the more rapid drop in arterial blood pressure, (2) the more severe pathological changes involving multiple organs, especially the lung and small intestine, (3) the increase of leukocyte adherence in venules and more pronounced rheological changes in the mesenteric microcirculation, and (4) the striking elevation of serum acid phosphatase (ACP), phospholipase A2 (PLA2) activity, and lipoperoxide (LPO). The changes of serum ACP, PLA2, and LPO in the rats with 80% GR blockade were more marked than in those with 50% GR blockade. Based on these findings, we propose that the decrease in GR during stress and shock might be a contributing factor in the pathogenesis of shock and multiple organ failure (MOF). The possible mechanisms of the above noted findings are discussed.

Acid Phosphatase↗
PubMed1993

The active site structure of the calcium-containing quinoprotein methanol dehydrogenase.

Pyrroloquinoline quinone (PQQ), widely found in nature, serves as the redox cofactor in bacterial methanol dehydrogenase (MEDH), a heterotetrameric enzyme that oxidizes methanol to formaldehyde. The refined structure of MEDH at 2.4-A resolution, based on recently obtained amino acid sequence data, reveals that the PQQ, located in a central channel of the disk-shaped protein, is sandwiched between a Trp side chain and a very unusual vicinal disulfide. A Ca2+ ion forms a bridge between PQQ and the protein molecule, very close to a putative substrate binding pocket. The vicinal disulfide may form during PQQ incorporation and possibly act to hold the latter in place.

Alcohol Oxidoreductases↗
PubMed1993

Identification of the regions conferring calmodulin-like properties to troponin C.

The structural and functional correlations between troponin C (TnC) and calmodulin (CaM) were investigated by mutagenizing a synthetic cDNA coding rabbit skeletal muscle TnC. Compared with TnC, calmodulin lacks the N-terminal alpha-helical arm (N-helix), and its central helix is shorter due to the absence of 88KGK90 residues. Deleting both regions concomitantly (delta Nt delta KGK) elicited CaM-like regulation as tested (i) by smooth muscle contractility (maximal tension = 80 +/- 5% Po of control) and (ii) by the activation of phosphodiesterase (Vmax = 75 +/- 2% of control). The Ca(2+)-binding capacity of the mutant and the effect of the mutant on maximally Ca(2+)-activated tension of skinned rabbit psoas muscle fibers were both conserved. Furthermore, in the linker region of the central helix, replacing the TnC-characteristic 85EDAKGK90 successive residues with CaM-specific DTD residues generated a highly effective CaM mimic (Vmax = 96 +/- 2%) whether or not the N-helix was also retained. Apparent KD values (i.e. concentrations for half-maximal response) for the successful mutants were similar to each other but about 200-fold higher than that for CaM. A part of the alpha-helical linker region in CaM may unfold and bend to promote multiplicity of target interaction using all four hands (Ikura, M., Clore, G. M., Gronenborn, A. M., Zhu, G., Klee, C. B., and Bax, A. (1992) Science 256, 632-638; Meador, W. E., Means, A. R., and Quiocho, F. A. (1992) Science 257, 1251-1255). In contrast, our results suggest that the TnC central helix evolved to be less pliable by the combined influences of 85EDAKGK90 residues and the alpha-helical extension in N terminus, thereby keeping the N-terminal hands well separated from their C-terminal counterparts.

Amino Acid Sequence↗
PubMed1993

[Diagnosis and treatment of cysticercosis of cerebral ventricles].

31 patients with cysticercosis of cerebral ventricles verified by operation or pathological investigation were reported. All patients were between 7 and 64 years of age and 14 were females. All had a single cyst. Since 29 patients (94%) were without a history of intestinal taeniasis, it was proposed that most patients of cysticercosis of cerebral ventricles were caused by hetero-infection and the entrance of Cysticercus into brain ventricle was through choroid plexus along the cerebrospinal fluid. This is probably the reason why it occurs mostly in the 4th ventricle. The clinical manifestation of cysticercosis of cerebral ventricles were paroxysmal headache and vomiting caused by increased intracranial pressure. Ventriculography and CT scanning have considerable diagnostic value. Removal of Cysticercus by surgical operation is successful (Figs. 1-8).

Adolescent↗
PubMed1993

[The effect of trilostane and dexamethasone on serum amino acids and TNF in endotoxemic rats].

By the use of specific endogenous GC biosynthesis inhibitor Trilostane and exogenous GC Dexamethasone (Dex), we established three rat models with similar severity of endotoxemia, but different plasma GC level. With these models we studied the effect of elevated plasma GC on serum TNF, pathological changes of vital organs and the changes in serum amino acids and glucose concentration in comparable endotoxemic condition. It was observed that plasma GC level was negatively correlated with the maximum TNF concentration, but positively correlated with the liver tyrosine transaminase activity, serum amino acids and glucose concentrations and as the serum GC level was elevated, the pathological changes of intestine, stomach, liver and lungs became less pronounced. From these results, it was supposed that in severe endotoxemia hypersecration of endogenous GC and maintenance of high level plasma GC are essential for animals to alleviate tissue injuries by reducing the overproduction of the host-derived mediators such as TNF and promoting the metabolism of amino acids and glucose.

3-Hydroxysteroid Dehydrogenases↗
PubMed1992

Pulmonary fat embolism in rabbits induced by forced immobilization.

In the study reported here, rabbits were used to develop an experimental model for inducing pulmonary fat embolism by forced immobilization. The emboli were quantitated by a computerized system. The activity of lipoprotein lipase in post-heparin plasma (PHP-LPL) and concentrations of free fatty acids (FFA) were measured. Also, blood gases were analyzed and pulmonary morphology and ultrastructure were observed. Forced immobilization for 5 hours was found to induce pulmonary embolism. This was accompanied by elevation of PHP-LPL and FFA levels in the blood, hypocapnia, and a tendency for insufficiency of pulmonary surfactant. The results suggest that the disorder of homeostasis caused by immobilization is strong enough to bring about pulmonary embolism without bone fracture.

Animals↗
PubMed1992

[Therapeutic results after resection of asymptomatic lung cancer].

This article reported a group of 43 cases of lung cancer who had no symptoms before resection, and were detected by mass screening or routine physical examination. They accounted for 15.2% of 282 cases undergoing lung cancer resection during the periods from January, 1977 to June, 1990 in our hospital. Pathologic study of the resected specimens showed that there were 32 cases of Stage I lung cancer (74.4%). Among them 15 cases were of early stage (T1N0M0) which accounted for 5.3% of 282 cases. 5-years survival rate of this subgroup was 81.8%. About one fourth of asymptomatic lung cancer belonged to middle or late stage.

Adenocarcinoma↗
PubMed1992

[Long-term effect of extracorporeal shockwave lithotripsy on kidney. A preliminary study].

We studied 139 patients with upper urinary tract calculi who were treated by JT-ESWL-I and III type extra corporeal shock wave lithotripter (ESWL) for an average of 4 years and 11 months. These patients aged below 45 had no history or family history of hypertension. Hypertension was found in 1 patient (0.7%) and elevated diastolic pressure in 6 (4.3%). The recurrence rate of calculi was 5%. Before and after ESWL, Bun, Cr, B2-mG (of blood and urine), activity of blood plasma renin AT-II, -GT, NAG, mucoprotein of plasma, etc were also determined. The differences in their values were not significant. We concluded that if the indications for ESWL are strictly considered including patient selection and number of wave pulsation and energy, ESWL is still an ideal method of treatment.

Adult↗
PubMed1991

Inducer-dependent conditional-lethal mutant animal viruses.

Regulatory elements of the Escherichia coli lac operon were used to construct an inducer-dependent conditional-lethal mutant animal virus. The gene encoding the repressor protein of the lac operon was integrated into the vaccinia virus genome so that it was expressed constitutively, and the lac operator was inserted next to the promoter of a gene that encodes an 11-kDa virion-associated protein of unknown function. The addition of inducer to the cell culture medium provided permissive conditions for isolation of a conditional-lethal mutant virus. Under nonpermissive conditions, the isolated virus did not form plaques, and the yield was decreased by at least 1000-fold under one-step growth conditions. Transcription of the operator-controlled gene was inducer-dependent and necessary for synthesis of the 11-kDa protein. Application of this mutagenesis strategy to other viruses is discussed.

Animals↗
PubMed1991

Vaccinia virus morphogenesis is interrupted when expression of the gene encoding an 11-kilodalton phosphorylated protein is prevented by the Escherichia coli lac repressor.

A conditional lethal vaccinia virus mutant, which constitutively expresses the Escherichia coli lac repressor and has the lac operator controlling the F18R gene (the 18th open reading frame of the HindIII F fragment of the vaccinia virus strain WR genome) encoding an 11-kDa protein, was previously shown to be dependent on the inducer isopropyl-beta-D-thiogalactoside (IPTG) for replication (Y. Zhang and B. Moss, Proc. Natl. Acad. Sci. USA 88:1511-1515, 1991). Further studies indicated that the yield of infectious virus could be regulated by titration with IPTG and that virus production was arrested by IPTG removal at appropriate times. Under nonpermissive conditions, an 11-kDa protein reactive with antiserum raised to a previously described DNA-binding phosphoprotein (S. Y. Kao and W. R. Bauer, Virology 159:399-407, 1987) was not synthesized, indicating that the latter is the product of the F18R gene. In the absence of IPTG, replication of viral DNA and the subsequent resolution of concatemeric DNA molecules appeared normal. Omission of IPTG did not alter the kinetics of early and late viral protein synthesis, although the absence of the 11-kDa polypeptide was noted by labeling infected cells with [35S]methionine or [32P]phosphate. Pulse-chase experiments revealed that proteolytic processing of the major viral structural proteins, P4a and P4b, was inhibited under nonpermissive conditions, suggesting a block in virus maturation. Without addition of IPTG, the failure of virus particle formation was indicated by sucrose gradient centrifugation of infected cell lysates and by the absence of vaccinia virus-mediated pH-dependent cell fusion. Electron microscopic examination of infected cells revealed that immature virus particles, with aberrant internal structures, accumulated when synthesis of the 11-kDa DNA-binding protein was prevented.

Animals↗
PubMed1991

[Effects of cholinergic agonists and antagonists on unit discharge of dorsal hippocampal CA1 area in rat].

The effects of icv cholinergic agonists (acetylcholine 6 micrograms, physostigmine 10 micrograms, and nicotine 20 micrograms) and cholinergic antagonists (scopolamine 40 micrograms and hexamethonium 250 micrograms) on 174 cells unit discharges of the dorsal hippocampal CA1 area in 42 rats were studied. The frequencies of the unit discharges were increased in 41 cells over 84 cells by icv M or N receptor cholinergic agonists, but reduced in 22 cells over 42 by M or N receptor cholinergic antagonists. After the electrolytic lesion of the septal region, the effects of acetylcholine and nicotine on unit discharges disappeared. The results indicated that the cholinergic agents changed the electric activity of cholinergic sensitive neurons via the septum-hippocampal cholinergic pathway.

Acetylcholine↗
PubMed1991

[Tongue picture of blood stasis symptom-complex].

The objective indices of tongue picture of blood stasis symptom-complex in 400 patients with portal hypertension, primary hepatic carcinoma, coronary heart disease, pulmonary heart disease, intermediate and advanced gastric carcinoma were observed during the period of past 6 years. Pale purplish tongue, purplish tongue, bluish purplish tongue, deep-red purplish tongue, dark tongue, yellow purplish tongue etc. were found in these patients. All these were the tongue colour of blood stasis. Ecchymosis, patechiae, streaks, the width of sublingual vein, the appearance of veins and prominences, B mode ultrasonic examination displaying the width of intralingual vein and tissue sound transmission of the tongue body, the blood stasis changes of tongue tip microcirculation, the wave form changes of tongue rheogram had an important significance for diagnosis of blood stasis. There were significant differences in these variables between the subject group and the healthy group or the subject group and the blood non-stasis group statistically (P less than 0.001).

Adult↗
PubMed1991

[IgE and IgE-mediated immunoreaction in the pathogenesis of human cysticercosis].

Total IgE, specific IgE and histamine in sera from 35 documented cases of cysticercosis and 30 transfusion donors were measured and mast cell degranulation test was performed. Total IgE levels (730.61 U/ml), the positive rate of specific IgE (85.7%), histamine levels (5.3 micrograms/ml) and the positive rate of mast cell degranulation (42.9%) of the patients were found to be significantly higher than those of the normal group (P less than 0.01). The results suggested that the antigen of Cysticercus cellulosae could induce IgE production and mast cell degranulation, resulting in the release of histamine. It was, therefore, deemed that the IgE and IgE-mediated immunoreaction might be involved in the pathogenesis of human cysticercosis.

Adult↗
PubMed1990

The effect of arsenic trioxide on brain monoamine metabolism and locomotor activity of mice.

The arsenic trioxide (AsT) content, and monoamine levels in the cerebral cortex, hippocampus, hypothalamus and corpus striatum were determined in mice administered AsT (3 and 10 mg/kg) for 14 days. The vertical and horizontal motor activity was also examined. The AsT content in discrete brain areas differed but was clearly dose-dependent. Metabolites of norepinephrine and dopamine increased in the cerebral cortex, hippocampus and hypothalamus and decreased in the corpus striatum in AsT-treated mice. Metabolites of 5-hydroxytryptamine increased in all the discrete brain areas. The vertical and horizontal motor activity was increased by AsT at 3 mg/kg and decreased by AsT at 10 mg/kg. These results show that AsT modifies CNS metabolism and function at low doses. AsT penetrates the blood-brain barrier to cause these effects.

Administration, Oral↗
PubMed1990

[Isolated jejunal grafting in surgery of esophageal carcinoma].

Six cases of either esophageal carcinoma or its post resection complications were treated by isolated jejunal grafting in our department in recent two years. Of the six cases, there were 2 of cervical anastomotic leakage after esophagocolostomy, 1 each of cervical anastomotic leakage after esophago-gastrostomy, cervical esophageal carcinoma, cervical anastomotic stricture after esophagogastrostomy, and defect of esophagus. Good results had been achieved in all of the six cases. Not a single death occurred. Indications for the use of isolated jejunal grafting and the operative techniques were discussed in detail. The author concludes that isolated jejunal grafting is worth recommending.

Adult↗