Biomedical subjects

H Zhao

Publications and source records attributed to H Zhao.

At least 307 records · Page 17Linked to original sources

PubMed1999

[The surgical treatment of congenital kyphosis].

OBJECTIVE: To summarize the treatment experience of congenital kyphosis, compare the results of several surgical procedures and conclude the lessons of failure cases with surgical treatment. METHODS: Retrospective analysis of 33 patients with surgical treatment of congenital kyphosis. These patients had a follow-up of 6 months to 14 years with an average follow-up of 5 years and 6 months. RESULTS: Among the 33 cases, the average age at surgery was 16.5 years old and the average kyphosis was 90.2 degrees. Four had anterior fusion, and 7 had posterior fusion only, and 22 had combined anterior and posterior fusion. The percentage of correction of the 3 procedures above mentioned was 32.7%, 34.4% and 41.2% respectively. All of the patients with incomplete paraplegia, but 2 had been recovered completely. CONCLUSIONS: The combined anterior and posterior fusion had a better correction than the anterior group or posterior group alone.

Adolescent↗

PubMed1999

[Design of blood cell analyzers by using stationary suspending laser light scattering method].

The paper analyses the technology development of automatic blood cell analyzers, put forward the new method of blood cell counting and classification by stationary suspending laser light scattering. The new automatic blood cell analyser is designed by using this method. The design idea of the light route and data acquisition system is stressly provided in the paper. The calibration is performed by using the standard blood cell particulate.

Adult↗

PubMed1999

[Photoacoustic spectroscopy investigation of intramolecular energy transfer in Eu-beta-disketones].

The complex crystals of Eu(III) with AA, HFA and TTA have been synthesized. The absorption intensities of Eu-AA, Eu-HFA and Eu-TTA are different while the photoacoustic (PA) signals of the corresponding solid complexes are almost the same, which shows that the probabilities for nonradiative transition of these chelates are different. The results of the fluorescence spectra are identical. The PA signal was obtained by detecting the heat generated through the nonradiative processes after absorption, and the intramolecular energy transfer processes of Eu-beta-diketones were studied from a new point of view.

English Abstract↗

PubMed1999

[The substituent structures and characteristic infrared spectra of alpha-furan esters].

The characteristic infrared bands of the alpha-furoic esters, alpha-furancarbinol esters and alpha-furanacrylic esters were assigned, and the changing rules of the IR absorption frequency of the alpha-furan esters with alpha-substituent structure were discussed. The results indicated there are three characteristic bands in alpha-furan ring. The strong absorption at 1641 cm(-1) is assigned to the C=C double bond stretching mode in the alpha-furanacrylic esters, while the absorption at 973 cm(-1) is the out-of-plane =C-H bending mode for a trans di-substituted alkene, the strong absorption at about 1713 cm(-1) is assigned to a C=O stretch, and the three strong absorptions near 1305, 1260 and 1165 cm(-1) are due to the symmetric and assymmetric stretching vibrations of C-O-C bond in the ester groups.

Esters↗

PubMed1999

[Fluorimetric study of Tb-EDTA-quercetin and determination of quercetin].

Tb-EDTA-Quercetin complexes were formed under basic conditions. Intramolecular energy transfer occurs in the Tb-EDTA complex with quercetin (QCT) and the terbium (III) ion fluorescence can be sensitized by QCT. Accordingly a fluorimetric method was used for the determination of QCT in urine, serum and mixed substance of rutin-quercetin. The method is simple, sensitive and fast. The linear range is 5.0 x (-7)-1.0 x10(-5) mol x L(-1) and the detection limit is 5.0 x 10(-8) mol x L(-1). This method can be applied to the determination of QCT in non-pretreated urine and serum successfully. The recoveries are in the range of 103%-96%.

Edetic Acid↗

PubMed1999

[Flow injection analysis of 3,4-dihydroxybenzoic acid with inhibited chemiluminescent detection].

It was found that 3,4-dihydroxybenzoic acid (protocatechuric acid) inhibited chemiluminescence of luminol-H2O2 reaction catalyzed by Co2+. On this basis, a flow injection method has been developed for the determination of protocatechuric acid. The method is simple, convenient and sensitive with detection limit of 2.7 x 10(-7) mol/L and is effective to determine protocatechuric acid in the range of 1 x 10(-6)-1 x 10(-5) mol/L. The variation coefficient of eleven determinations for 8 x 10(-6) mol/L protocatechuric acid is 2.3%.

English Abstract↗

PubMed1999

[Study of the fluorescence of terbium-pipemidic acid system and the determination of pipemidic acid in urine and serum].

Intramolecular energy transfer occurs in the terbium complex with pipemidic acid (PPA) and the terbium(III) ion fluorescence can be sensitized by PPA. The fluorescence intensity of the Tb3+-PPA system is proportional to the amount of PPA. Accordingly, a fluorimetric method for the determination of PPA is proposed. The characteristics of the method include low background noise, high selectivity and long fluorescence lifetime. The method can be applied to the determination of PPA in urine and serum. The recovery is in the range of 94.6%-102%. Its detection limit and linear range for PPA are 3.6 ng/mL and 5.0 x 10(-8)-4.0 x 10(-6) mol/L, respectively.

Fluorescence↗

PubMed1999

Reciprocal role of the AT1 receptor in modulating renal and neuronal AT1 mRNA expression.

This study was designed to explore the mechanisms mediating the expression of the type 1 angiotensin II (AngII) receptor (AT1) in neuronal and renal tissues. Four groups of rats were given 1% NaCl in water and subjected to the renal reduced mass protocol (RRM), RRM + ramipril (Ram, 10 mg/kg per d), RRM + candesartan (Can, 10 mg/kg per d), or sham surgery. After 12 d, mean arterial pressure (MAP) was significantly higher in RRM rats than in RRM + Ram, RRM + Can, and sham-operated rats. Northern blot analysis showed that renal AT1 receptor mRNA levels (AT1 mRNA/18 rRNA) were significantly decreased in RRM (1.08+/-0.05) and RRM + Ram (0.82+/-0.02) compared with sham-operated rats (1.38+/-0.06) and that candesartan treatment caused a further decrease in renal AT1 mRNA content (0.73+/-0.07) compared with RRM. In contrast, dorsal root ganglia AT1 receptor mRNA content was significantly decreased in RRM (0.52+/-0.06) compared with sham-operated rats (1.18+/-0.07), and this decrease was abolished by ramipril (1.40+/-0.13) and candesartan treatment (1.56+/-0.11). RIA showed that levels (ng/mg protein) of calcitonin gene-related peptide (CGRP) in the dorsal root ganglia were significantly increased in RRM (1.60+/-0.11) but not in RRM + Ram (1.14+/-0.20) and RRM + Can (1.18+/-0.09), compared with sham-operated rats (0.94+/-0.05). Thus, RRM-induced downregulation of neuronal AT1 mRNA expression is mediated by AngII activation of the AT1 receptor, whereas an AT1-independent mechanism is operant in mediating renal AT1 gene expression. Furthermore, the inverse relationship between neuronal AT1 expression and CGRP content indicates that activation of the neuronal AT1 receptor inhibits CGRP synthesis in the dorsal root ganglia. The functional implications of these findings are discussed.

Angiotensin I↗

PubMed1999

Histopathological changes in hepatocellular carcinoma after hepatic arterial embolization.

Hepatic arterial embolization (HAE) is used to treat hepatocellular carcinoma (HCC), but little is known about the histopathological changes occurring after HAE. Thirty-nine cases of liver neoplasms treated with HAE and 11 cases of liver neoplasms after digital selective angiography (DSA) were analyzed histopathologically. The pathological type, histological grade, degree of necrosis, capsular changes, number of HAE, vessel injury, and lymphocytic infiltration were recorded. Six cases showed 100% necrosis, 14 cases had 30 to 95% necrosis, and 19 cases 0 to 5% necrosis after HAE. Eleven cases of DSA did not reveal histological features of necrosis. The necrosis was related to the pathological type of tumor, encapsulation, and degree of vascular injury and was independent of histological grade, number of HAE, or lymphocytic infiltration of the neoplasm. HAE is an effective therapy for advanced stage of HCC. The encapsulated HCC is a preferred indicator for HAE.

Adult↗

PubMed1998

Minimal effect of brain temperature changes on glutamate release in rat following severe global brain ischemia: a dialysis electrode study.

Using a dialysis electrode, we recently developed an oxygen-independent system for real-time measurement of the glutamate concentration in the extracellular space ([Glu]e) during ischemia. This system allows separate evaluation of intra-ischemic biphase [Glu]e elevation, i.e. release from synaptic vesicles (1st phase), reversed uptake of glutamate from metabolic pools in neuronal cells (2nd phase), and post-ischemic glutamate re-uptake in ischemia-reperfusion models. Using the system, we attempted to clarify the relationship between biphase glutamate release and brain temperature in a model of acute global ischemia produced by transecting both carotid arteries. Our results showed that, in contrast to mild hyperthermia, hypothermia did not inhibit the 1st phase of [Glu]e release, and changes in intra-ischemic brain temperature had a minimal effect on the 2nd phase of [Glu]e elevation during severe acute ischemia. These findings, together with our previous data, indicate that brain temperature change in the intra-ischemic period plays an important role in disturbance of the glutamate re-uptake system during ischemia.

Animals↗

PubMed1998

The relationship between biological activity and the electronic structure and transfer of the whole acidic PLA2 molecule in ab initio level.

The electronic structure of the whole molecule of acidic phospholipase A2 (PLA2) from the venom of Agkistrodon halys pallas (A. halys pallas) has been calculated using the extended negative factor counting (ENFC) method in which dimers were calculated at the ab initio level using a minimal basis set, with simulation of the aqueous environment. Hopping conductivities were determined by the use of random walk theory. The results show that the frontier orbitals are mainly localized to residues which are involved in the biological activity of acidic PLA2. The C-terminal region might play some important role in biological activity because of its active electrons. The aromatic patch on the surface of the enzyme, together with two neighbouring acidic residues, has very active electrons that may be responsible for the inhibition of platelet aggregation. Trp30, which is involved in the interfacial recognition region, may transfer its electrons to the aggregated substrate. It is also concluded that the conductivity of the protein is caused mainly by holes transported through the valence band rather than electrons transferred in the conductive band. The a.c. conductivity of acidic PLA2 confirms that proteins, if doped, are amorphous conductors. Moreover, the a.c. conductivities of acidic PLA2 are approximately one order of magnitude higher than those of some other proteins. This suggests that the toxicity of acidic PLA2 may be related to its high a.c. conductivity.

Agkistrodon↗

PubMed1998

Serum levels of substance P are elevated in patients with sickle cell disease and increase further during vaso-occlusive crisis.

As a mediator of neurogenic inflammation and pain, we hypothesized that levels of the neuropeptide Substance P (SP) would be elevated in patients with sickle cell disease (SCD) with vaso-occlusive pain crisis. SP is a known stimulator of tumor necrosis factor-alpha (TNF-alpha) release and a promoter of interleukin-8 (IL-8), which are reported to be increased in SCD. These cytokines enhance adhesion of leukocytes to endothelium and may play a role in vaso-occlusive events. Serum levels of IL-8, TNFalpha, and SP were studied in three groups of children aged 2 to 18 years: 30 well children with SCD, 21 with SCD in pain crisis, and 20 healthy age-matched controls. Serum levels of SP were elevated in all SCD patients and were highest in patients in pain crisis. The percentage of sera with detectable levels of IL-8 (>5.0 pmol/L) was increased in SCD patients as compared with the control group. IL-8 levels were similar for well SCD patients and those with pain. TNFalpha levels were not significantly different among the three groups. In three children with SCD, SP was measured at baseline and again during pain crisis. In each case, serum levels during pain crisis were higher than they were when the patient was well. We conclude that levels of SP are high in patients with SCD and increase during pain crisis. These results imply that SP plays a prominent role in the pain and inflammation of SCD and may be a measurable laboratory marker of vaso-occlusive crisis. We speculate that neurokinin receptor antagonists may have a therapeutic potential in the treatment of crisis pain.

Acute Disease↗

PubMed1998

Regulation of zinc homeostasis in yeast by binding of the ZAP1 transcriptional activator to zinc-responsive promoter elements.

Zinc homeostasis in yeast is controlled primarily through the regulation of zinc uptake. Transcription of the ZRT1 and ZRT2 zinc transporters increases in zinc-limited cells, and this induction is dependent on the ZAP1 gene. We hypothesized previously that ZAP1 encodes a zinc-responsive transcriptional activator. Expression of ZAP1 itself increases in zinc-limited cells. This response is also dependent on ZAP1 function through a potential positive autoregulatory mechanism. In this report, we describe the characterization of zinc-responsive elements (ZREs) in the promoters of the ZRT1, ZRT2, and ZAP1 genes. A ZRE consensus sequence, 5'-ACCYYNAAGGT-3', was identified and found to be both necessary and sufficient for zinc-responsive transcriptional regulation. We also demonstrate that ZREs are DNA binding sites for ZAP1. First, a dominant ZAP1 mutation, ZAP1-1(up), which causes increased expression of ZAP1-regulated genes in zinc-replete cells, exerted its effects specifically through the ZREs. Second, electrophoretic mobility shift assays and in vitro DNase I footprint analyses indicated that ZAP1 binds to ZREs in a sequence-specific fashion. These studies demonstrate that ZAP1 plays a direct role in controlling zinc-responsive gene expression in yeast by binding to zinc-responsive elements in the promoters of genes that it regulates.

Alleles↗

PubMed1998

Effects of brain temperature on CBF thresholds for extracellular glutamate release and reuptake in the striatum in a rat model of graded global ischemia.

We simultaneously measured extracellular glutamate ([Glu]e) elevation and local CBF using a real-time monitoring method and laser-Doppler flowmetry, respectively, in the rat striatum in a modified graded global ischemia model. Ischemic brain temperatures were kept at 32 degrees C, 37 degrees C and 39 degrees C. Three distinct types of intraischemic [Glu]e elevation, reflecting mild, moderate and massive glutamate release, were observed. Brain temperature plays an important role in determining CBF thresholds for each of the three types of [Glu]e elevation. CBF thresholds for [Glu]e elevations shifted to a lower level range as brain temperature was reduced. In mild or moderate ischemia, there is no exposure to sustained [Glu]e elevation, which is seen only in relatively severe ischemia characterized by biphasic [Glu]e elevation.

Animals↗

PubMed1998

Molecular interaction between the Fyn-associated protein SKAP55 and the SLP-76-associated phosphoprotein SLAP-130.

It has previously been reported that in resting T-lymphocytes the protein tyrosine kinase p59 constitutively co-precipitates with four phosphoproteins of 43, 55, 85, and 120 kDa, respectively. We have recently cloned the 55-kDa protein that was termed Src kinase-associated phosphoprotein of 55 kDa (SKAP55). Here we demonstrate that the recently characterized SH2-domain-containing leukocyte protein 76-associated phosphoprotein of 130 kDa (SLAP-130) is one of the components of the Fyn complex and that it also co-precipitates with SKAP55 in human T-cells. We establish that SKAP55 and SLAP-130 associate with each other when both molecules are co-expressed in COS cells. By co-transfection of truncated mutants of SKAP55 and SLAP-130 as well as by using the two-hybrid selection system, we further demonstrate that the association between SLAP-130 and SKAP55 is direct and involves the Src homology 3 domain of SKAP55 and the proline-rich sequence of SLAP-130.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Solution structure of a Na cation stabilized DNA quadruplex containing G.G.G.G and G.C.G.C tetrads formed by G-G-G-C repeats observed in adeno-associated viral DNA.

We have applied NMR and molecular dynamics computations including intensity based refinement to define the structure of the d(G-G-G-C-T4-G-G-G-C) dodecanucleotide in 100 mM NaCl solution. The G-G-G-C sequence is of interest since it has been found as tandem repeats in the DNA sequence of human chromosome 19. The same G-G-G-C sequence is also seen as islands in adeno-associated virus, a human parvovirus, which is unique amongst eukaryotic DNA viruses in its ability to integrate site-specifically into a defined region of human chromosome 19. The d(G-G-G-C-T4-G-G-G-C) sequence forms a quadruplex in Na cation containing solution through head-to-tail dimerization of two symmetry-related stem-hairpin loops with adjacent strands antiparallel to each other around the quadruplex. The connecting T4 loops are of the lateral type, resulting in a quadruplex structure containing two internal G.G.G.G tetrads flanked by G.C.G.C tetrads. The G(anti).G(syn).G(anti).G(syn) tetrads are formed through dimerization associated hydrogen bonding alignments of a pair of Hoogsteen G(anti).G(syn) mismatch pairs, while the G(anti).C(anti).G(anti).C(anti) tetrads are formed through dimerization associated bifurcated hydrogen bonding alignments involving the major groove edges of a pair of Watson-Crick G.C base-pairs. The quadruplex contains two distinct narrow and two symmetric wide grooves with extensive stacking between adjacent tetrad planes. The structure of the quadruplex contains internal cavities that can potentially accommodate Na cations positioned between adjacent tetrad planes. Three such Na cations have been modeled into the structure of the d(G-G-G-C-T4-G-G-G-C) quadruplex. Finally, we speculate on the potential role of quadruplex formation involving G.G.G.G and G.C.G.C tetrads during the integration of the adeno-associated parvovirus into its target on human chromosome 19, both of which involve stretches of G-G-G-C sequence elements.

Chromosomes, Human, Pair 19↗

PubMed1998

Cryopreservation and transplantation of dog trachea.

In order to meet the need of trachea transplantation for clinical application, it is important to research the methods of cryopreservation and transplantation of trachea. By the thermal analyses and thermal control techniques, combined with electron microscopy, the effects of cooling and warming rates with different concentrations of cryoprotective agents were studied. Also the transplantation technique was studied, eighty five percent (17/20) of the dogs were survival after the transplantation with cryopreserved tracheas.

Animals↗

PubMed1998

Salicylhydrazine-containing inhibitors of HIV-1 integrase: implication for a selective chelation in the integrase active site.

In previous studies we identified N,N'-bis(salicylhydrazine) (1) as a lead compound against purified recombinant HIV-1 integrase. We have now expanded upon these earlier observations and tested 45 novel hydrazides. Among the compounds tested, 11 derivatives exhibited 50% inhibitory concentrations (IC50) of less than 3 microM. A common feature for activity among these inhibitors is the hydroxyl group of the salicyl moiety. Although the active inhibitors must contain this hydroxyl group, other structural modifications can also influence potency. Removal of this hydroxyl group or replacement with an amino, bromo, fluoro, carboxylic acid, or ethyl ether totally abolished potency against integrase. Several asymmetric structures exhibited similar potency to the symmetric lead inhibitor 1. The superimposition of the lowest-energy conformations upon one another revealed three sites whose properties appear important for ligand binding. Site A is composed of the 2-hydroxyphenyl, the alpha-keto, and the hydrazine moieties in a planar conformation. We propose that this site could interact with HIV-1 integrase by chelation of the metal in the integrase active site as inhibition of HIV-1 integrase catalytic activity and DNA binding were strictly Mn2+-dependent. The hydrophobic sites B and C are probably responsible for complementarity of molecular shape between ligand and receptor. Our data indicate that only those compounds which possessed sites A, B, and C in a linear orientation were potent inhibitors of HIV-1 integrase. Although all the active inhibitors possessed considerable cytotoxicity and no apparent antiviral activity in CEM cells, the study presents useful information regarding ligand interaction with HIV-1 integrase protein.

Binding Sites↗