Biomedical subjects

K Zhang

Publications and source records attributed to K Zhang.

At least 145 records · Page 8Linked to original sources

PubMed2000

[Penetrating wounds of the heart: analysis of 56 patients].

OBJECTIVE: To assess the management of penetrating cardiac injuries. METHODS: 56 patients with penetrating wounds of the heart were studied retrospectively. The study lasted for 11 years. RESULTS: Stab wounds accounted for 89.3% of the 56 patients. 56 patients underwent thoracotomy. Preoperative infusion was less than 1,000 ml in 68% of the patients. Preoperative pericardiocentesis was done only in 2 patients, of whom one was false negative. Four patients with cardiac arrest soon after arrival were subjected to emergency thoracotomy; three survived. After the operation, 2 patients died of associated abdominal injuries and failure of cerebral resuscitation. The overall survival rate was 96.4%. CONCLUSIONS: Early diagnosis and prompt thoracotomy are essential to the treatment of penetrating cardiac injuries. Preoperative massive transfusion and pericardiocentesis are not advocated.

Adolescent↗

PubMed2000

[Adsorption behavior of chromate onto activated carbon particles].

In this paper, the adsorption behavior of chromate onto activated carbon particles was studied as a function of pH, flow rate and the concentration of tested anion. The results showed that chromate anion was not only reduced but also adsorbed by activated carbon particles, the percentages of reduction and adsorption were strongly dependent on the pH value and the flow rate. In the medium of pH < 10, chromate anion could be adsorbed directly onto the activated carbon particles and the adsorbed chromate could be eluted from activated carbon particles by 1 mol/L NaOH without valence change. The reduced product of chromate anion was mainly Cr (VI), Cr(VI) could be adsorbed in the pH > 4 medium by the activated carbon particles and eluted with 1%H2SO4.

Adsorption↗

PubMed2000

[Study on biodegradation of phenols in river water].

This study on the biodegradation of phenols (phenol, o-methylphenol, o-chlorophenol and resorcinol) in river water was conducted by changing the main influential factors respectively. The results of experiment showed the phenols were greatly degradated in mild temperature, neutral pH and plenty of oxygen and the rank of the phenols biodegradation from great to small was resorcinol, phenol, o-methylphenol and o-chlorophenol. Presented in this paper is also a discussion on the biodegradation mechanism of phenols.

Biodegradation, Environmental↗

PubMed2000

[Isolation, purification and bioactivities of exopoly saccharides from fermented broth of Ganoderma lucidum].

The exopolysaccharides of Ganoderma lucidum(GLEP) extracted from the fermentation broth after removing protein by Sevage and protease digestion procedures, were applied to a column of DEAE-cellulose(OH- form), and eluted stepwise with distilled water, sodium hydrogen carbonate (0.1 mol/L, 0.3 mol/L, 0.5 mol/L successively) and 0.1 mol/L sodium hydroxide. Five fractions were obtained, and the main fraction was known as GLEP-I, furthermore subjected to chromatography on a column of SepharoseC1-6B, eluted at a flow rate of 30 mL/(cm2.h), the relative viscosity of sample solution of 1.5. Two fractions, GLEP-IFr1 and GLEP-IFr2 with a ratio of 3.8:1, were obtained. Molecular weight of GLEP-IFr1 and GLEP-IFr2 was estimated to be 38,000 and 22,000 Dalton respectively by Membrane Osmometer. The animal test showed that GLEP-IFr1 could inhibited the growth of Sarcoma 180 tumor in mice. The average inhibition ratio was 57.4% (i.p. 10 mg/kg for 10 days). The result of immunological activity showed that GLEP-IFr1 could significantly improve macrophage cytophagy.

Animals↗

PubMed2000

[Long-term observation on two types of surgical operations for idiopathic hemifacial spasm].

OBJECTIVE: To evaluate and compare the long-term curative effects of two types of surgical operations, microvascular decompression (MVD) and microneurovascular decompression neurocombing neurotraction draw (MVDCTD) for idiopathic hemifacial spasm (IHFS). METHODS: Five hundred and fifty-four patients with complete medical records and with at least 3-year followed-up had been collected since 1985. RESULTS: Of 148 MVD-treated cases with the longest follow-up of 13 years and 9 months, 117 cases were free of symptoms, giving a 79.05% cure rate. Thirty-one patients had recurrence of the symptoms, giving a 20.95% recurrence rate. Of 406 cases treated by MVDCTD with the longest follow-up of 12 years and 3 months, 374 were cured, giving a 92.12% cure rate, and 32 had recurrences of symptoms, giving a 7.88% recurrence rate. Most of them recurred within 2 years after the operation. Complications were sensorineural hearing loss in 31 patients (23 temporary, 8 permanent), temporary tinnitus in 22, temporary postoperative facial weakness in 78, and postoperative meningitis in 34 (3.13%, 33 cases were controlled with antibiotics and 1 patient died). CONCLUSION: The vascular compression at the root of the facial nerve is a main cause of IHFS, and the abnormal function of the facial nucleus is also one of the causes. MVDCTD for IHFS is characterized by its high curative rate, low recurrent rate and stable long-term effect, and is superior to the MVD.

Adult↗

PubMed2000

[Effect of macrophage nitric oxide on the ultrafiltration failure of long-term peritoneal dialysis].

OBJECTIVE: The regulation of macrophage nitric oxide on peritoneal lymphatic stomata was studied for revealing the mechanism of ultrafiltration failure during long-term peritoneal dialysis. METHODS: (1) The model of peritoneal dialysis was created by using peritoneal dialysate; (2) Dynamic measurements of nitric oxide (NO) were made during peritoneal dialysis and its cessation; (3) The pathological change of the peritoneal mesothelium in different dialysis time was observed by scanning electron microscope (SEM); (4) Dynamic changes of the peritoneal lymphatic stomata were studied during this experiment by using a computer image processing system attached to SEM. RESULTS: Numerous macrophages went into the peritoneal cavity through the lymphatic stomata to form a lot of milky spots during peritoneal dialysis. A great quantity of NO produced by macrophages damaging mesothelial cells and increasing numbers and density of lymphatic stomata. After 40 days of peritoneal dialysis, the diameters of the lymphatic stomata were significantly increased in Bieffe group (P < 0.05). During cessation of peritoneal dialysis, few macrophage milky spots were observed and NO quantity was gradually decreased. Then the mesothelium damage began to repair and the peritoneal lymphatic stomata tended to become normal. CONCLUSIONS: Our data demonstrate that a great quantity of NO produced by macrophages would damage peritoneal mesothelium and relax lymphatic stomata which enhance lymphatic reabsorption from the peritoneal cavity so as to make ultrafiltration failure on long-term peritoneal dialysis.

Absorption↗

PubMed2000

[Luminescence of zinc and europium composite alpha-thiophene carboxylate].

Zinc and europium composite alpha-thiophene carboxylate with very strong red luminescence was prepared from zine oxide, europium oxide, and alpha-thiophene carboxylic acid by a rheologic phase reaction method. The thermal stability and X-ray diffraction pattern were measured. The IR, UV, excitation and emission spectra were studied. The influence of zinc ion and thiophene on luminescence intensity was discussed. In zinc and europium composite alpha-thiophene carboxylate, zinc ion can reduce the concentration quenching and effectively enhance the luminescence of Eu3+ ion, thiophene ring can increase the luminescence efficiency.

Carboxylic Acids↗

PubMed2000

[Determination of trace elements Cu, Zn, Mg, Cr, Mn in serum of people with hepatoma, cirrhosis, hepatapstema disease].

Using AAS method, we detected serum Zn, Cu, Mn, Cr, Mg in the people with hepatoma, cirrhosis and hepatophyma disease. The results showed that the level of serum Cu of people with hepatoma and cirrhosis were significantly higher than those in the healthy control and with hepatophyma disease (P < 0.01). The levels of serum Mn, Cr of those with hepatoma and cirrhosis disease were significantly lower than those with hepatophyma and the healthy control (P < 0.01). It is concluded that determination of Cu, Mn, Cr may be one of the methods to diagnose hepatoma and cirrhosis disease.

Adolescent↗

PubMed2000

[Studies on synthesis and IR spectrum of nickel salicylates complexes].

Nickel salicylates complexes were synthesized with the rheologic phase reaction method. The composition of these complexes were confirmed by elemental analysis, TG and IR, the principal infrared absorption peaks were assigned for the region 4,000-400 cm-1. The IR spectra indicated that a hydroxyl group on Ni atom was occurred and so absorption peaks of hydroxyl group were shifted obviously to higher frequency in nickel monosalicylates.

Chelating Agents↗

PubMed1999

Essential protein-protein interactions between Plasmodium falciparum thymidylate synthase and dihydrofolate reductase domains.

In Plasmodium falciparum, dihydrofolate reductase and thymidylate synthase activities are conferred by a single 70-kDa bifunctional polypeptide (DHFR-TS, dihydrofolate reductase-thymidylate synthase) which assembles into a functional 140-kDa homodimer. In mammals, the two enzymes are smaller distinct molecules encoded on different genes. A 27-kDa amino domain of malarial DHFR-TS is sufficient to provide DHFR activity, but the structural requirements for TS function have not been established. Although the 3'-end of DHFR-TS has high homology to TS sequences from other species, expression of this protein fragment failed to yield active TS enzyme, and it failed to complement TS(-) Escherichia coli. Unexpectedly, even partial 5'-deletion of full-length DHFR-TS gene abolished TS function on the 3'-end. Thus, it was hypothesized that the amino end of the bifunctional parasite protein plays an important role in TS function. When the 27-kDa amino domain (DHFR) was provided in trans, a previously inactive 40-kDa carboxyl-domain from malarial DHFR-TS regained its TS function. Physical characterization of the "split enzymes" revealed that the 27- and the 40-kDa fragments of DHFR-TS had reassembled into a 140-kDa hybrid complex. Thus, in malarial DHFR-TS, there are physical interactions between the DHFR domain and the TS domain, and these interactions are necessary to obtain a catalytically active TS. Interference with these essential protein-protein interactions could lead to new selective strategies to treat malaria resistant to traditional DHFR-TS inhibitors.

Animals↗

PubMed1999

Design and synthesis of novel alpha(1)(a) adrenoceptor-selective antagonists. 3. Approaches to eliminate opioid agonist metabolites by using substituted phenylpiperazine side chains.

Dihydropyrimidinones, such as 1, represent a novel class of alpha(1a) adrenoceptor antagonists with potential for the treatment of benign prostatic hyperplasia (BPH) (see part 1 of this series). Analysis of the metabolites of 1 revealed that 4-methoxycarbonyl-4-phenylpiperidine is formed as the major metabolite and is an agonist at the mu-opioid receptor. To circumvent any potential liability resulting from the metabolite, we decided to identify alternate templates devoid of agonist activity at the mu-opioid receptor to replace the 4-methoxycarbonyl-4-phenylpiperidine moiety. The present study describes the synthesis and SAR of dihydropyrimidinones linked to substituted 4-phenylpiperazine containing side chains. Compound (+)-38 was identified as a lead compound with a binding and functional profile comparable to that of 1. The putative metabolite 2-carboxamidophenylpiperazine has negligible affinity for the mu-opioid receptor.

Adrenergic alpha-Antagonists↗

PubMed1999

Design and synthesis of novel alpha(1)(a) adrenoceptor-selective antagonists. 4. Structure-activity relationship in the dihydropyrimidine series.

We have previously disclosed dihydropyridines such as 1a,b as selective alpha(1a) antagonists as a potential treatment for benign prostatic hyperplasia (BPH). The propensity of dihydropyridines toward an oxidation led us to find suitable replacements of the core unit. The accompanying papers describe the structure-activity relationship (SAR) of dihydropyrimidinones 2a,b as selective alpha(1a) antagonists. We report herein the SAR of dihydropyrimidines such as 4 and highlight the similarities and differences between the dihydropyrimidine and dihydropyrimidinone series of compounds.

Administration, Oral↗

PubMed1999

Structure, alternative splicing, and expression of the human RGS9 gene.

An isoform of RGS9 was recently identified as the GTPase activating protein in bovine and mouse rod and cone photoreceptors. To explore the potential role of the RGS9 gene in human retinal disease, we determined its exon/intron arrangement, and investigated its expression in human retina. The results show that the gene, located on 17q24, consists of 19 exons and spans more than 75kb of genomic DNA. The entire gene was found to be contained on a single BAC clone with an insert size of 170kb. The major transcripts of the gene are alternatively spliced into a 9.5kb retina-specific transcript (RGS9-1) and a brain specific 2.5kb transcript (RGS9-2). Exons 1-16 are constitutive and present in both variants. Exon 17 contains the 3' end of the open reading frame and the 3'-UTR of the RGS9-1 variant. In RGS9-2, exon 17 is alternatively spliced and joined to exons 18 and 19 that are not present in the retina variant. Immunolocalization with a monoclonal antibody recognizing the retina and brain variants shows abundant expression in photoreceptors and possibly very low levels in cell types of the inner retina. Owing to the specific expression of RGS9-1 in photoreceptors the RGS9 gene is a candidate gene for RP17, a form of autosomal retinitis pigmentosa, located on the long arm of chromosome 17.

Aged↗

PubMed1999

Effects of alkylating agents on dopamine D(3) receptors in rat brain: selective protection by dopamine.

Dopamine D(3) receptors are structurally highly homologous to other D(2)-like dopamine receptors, but differ from them pharmacologically. D(3) receptors are notably resistant to alkylation by 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), which readily alkylates D(2) receptors. We compared EEDQ with N-(p-isothiocyanatophenethyl)spiperone (NIPS), a selective D(2)-like receptor alkylating agent, for effects on D(3) and D(2) receptors in rat brain using autoradiographic analysis. Neither agent occluded D(3) receptors in vivo at doses that produced substantial blockade of D(2) receptors, even after catecholamine-depleting pretreatments. In vitro, however, D(3) receptors were readily alkylated by both NIPS (IC(50)=40 nM) and EEDQ (IC(50)=12 microM). These effects on D(3) sites were blocked by nM concentrations of dopamine, whereas microM concentrations were required to protect D(2) receptors from the alkylating agents. The findings are consistent with the view that alkylation of D(3) receptors in vivo is prevented by its high affinity for even minor concentrations of endogenous dopamine.

Alkylating Agents↗

PubMed1999

Selective alkylatation of dopamine D2 and D4 receptors in rat brain by N-(p-isothiocyanatophenethyl)spiperone.

Effects of the D2-like receptor alkylating agent NIPS (N-[p-isothiocyanatophenethyl]spiperone) on dopamine receptors in rat brain were characterized by radioreceptor assays and quantitative autoradiography. NIPS alkylated D2 and D4 receptors concentration-dependently in brain sections and transfected cells. NIPS also alkylated both receptors dose-dependently in vivo, with no effect on dopamine D1-like or serotonin 5-HT2 receptors at a dose that occluded 75% of D2 and D4 receptors. Pretreatment with D2-like receptor selective antagonist haloperidol completely blocked the effects of NIPS. The findings demonstrate that NIPS selectively alkylates D2 and D4 receptors, indicating its potential utility for studies of these receptors.

Alkylation↗

PubMed1999

Identification of seven serotypes of bluetongue virus from the People's Republic of China.

Seven serotypes (1, 2, 3, 4, 12, 15 and 16) of bluetongue virus were isolated from the blood of sheep and cattle in the People's Republic of China between 1986 and 1996. Six of these viruses were isolated in Yunnan province. The sheep from which serotypes 1 and 16 were isolated showed obvious signs of bluetongue disease, whereas the cattle from which serotypes 2, 3, 4, 12 and 15 were isolated were clinically normal. Phylogenetic analyses of these viruses indicate that they are more closely related to one another, and to an Australian strain of serotype 1, than they are to prototype strains of bluetongue virus serotypes 2, 10, 11, 13 and 17 from the USA.

Animals↗

PubMed1999

Characterization of the effect on adhesion of different mutations in myelin P0 protein.

Table 1 summarizes the results obtained from expressing in CHO cells C21A P0 and N93A P0 alone, and each with wild-type P0. As can be seen, each of these mutated proteins reach the cell surface when expressed alone, but neither is adhesive. Finally, when each of these mutated P0 molecules is expressed with the wild-type P0, wild-type P0 is no longer adhesive. Therefore, both C21A Po and N93A P0 each have a dominant negative effect on adhesion of wild-type P0. This approach to address the functional consequences of mutations in P0 can now be used to assess the effects of different mutations associated with CMT1B.

Amino Acid Substitution↗

PubMed1999

Effects of noradrenergic lesions on the development of rolipram-sensitive, low-K(m), cyclic AMP specific phosphodiesterase in rat brain.

Rolipram-sensitive, low-K(m)80% loss of norepinephrine in cerebral cortex) without affecting dopaminergic systems. The lesions resulted in temporary reduction of PDE4 activity in cerebral cortex, cerebellum and brainstem. Lesions in the adult rats, on the other hand, did not alter PDE4 activity. Decreased PDE4 activity by neonatal noradrenergic lesions was due to a decrease in the V(max) of cAMP hydrolysis by PDE4, and not a change in the K(m) values. Immunoblot analysis showed that decreased PDE4 activity in cerebellum was associated with reduced expression of PDE4A5, PDE4A1, and several PDE4B variants. No change in the expression of any PDE4 subtype in cerebral cortex was detected with the antibodies used in this study. Neither the permanent loss of noradrenergic innervation in cerebral cortex, nor the permanent noradrenergic hyperinnervation in brainstem was accompanied by any permanent change in PDE4 activity. Decreasing PDE4 activity early after neonatal noradrenergic lesions might be important in maintaining constant concentrations of cAMP, which is critical for the cellular proliferation and differentiation that is active during this period.

Amino Acid Sequence↗