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Biomedical subjects

G Zhao

Publications and source records attributed to G Zhao.

At least 217 records · Page 12Linked to original sources
PubMed1997

[Investigation of the carboxymethyl hydroxypropyl guar gum cross-linked with metal ions].

In this paper the infrared-spectral changes and thermal gravimetric analysis of the gels formed with carboxymethyl hydroxypropyl guar gum (CMHPG) cross-linked with metal ions (Fe3+, Cr3+, Ti4+) have been studied. The results indicated that the coordinated active sites are mainly supplied with hydroxypropyl, neigbouring cis-OH of main chain and carboxymethyl groups of CMHPG. And the results of spectral analysis showed the strength orders and coordinated mode of the guar gum cross-linked with metal ions.

Cross-Linking Reagents↗
PubMed1997

[Application of wavelet transform to the isolation of EXAFS oscilations from experiment data].

It is of significant importance to isolate lambda(k) form the total absorption cofficient data micro(E) for the analysis of EXAFS spectrum. Generally, least-squares procedure of polynomial spline or B spline was used for removing the smooth sbsorption background, which has been proved to be effective. But it suffers in that the trial of knot points is time-consuming and it is poor in reproducibility. In this paper, a new chemometrics method--wavelet transform analysis was used to separate the lambda(k) and background absorption from micro(E) and it is proved that the technique is a very good method for the analysis of EXAFS spectrum.

English Abstract↗
PubMed1997

[Study on the arylaminothiourea compounds by IR spectroscopy].

In this paper, eleven new thiourea compounds were prepared and studied by IR spectroscopy. The fundamental vibrations have been assigned. The band near 1540cm(-1) was identified as thiourea I band, which mainly originated from the N-H deformation vibration coupling with a little C-N stretching vibration. Thiourea I band near 1280cm(-1) mainly originated from C-N stretching vibration. C=S stretching vibration frequency was at near 110cm(-1) and it was identified as thiourea III band.

English Abstract↗
PubMed1997

Role of candidate modifier genes on the phenotypic expression of hypertrophy in patients with hypertrophic cardiomyopathy.

BACKGROUND: The phenotypic expression of left ventricular hypertrophy (LVH) in patients with hypertrophic cardiomyopathy (HCM) is variable. This phenotypic variability is not completely explained by the responsible mutations or other known factors. Recent data denote a role for the modifier genes and environmental factors. We studied the role of 3 potential modifier genes, i.e., angiotensinogen (AGT), angiotensin II receptor 1a (AT1a), and endothelin-1 (END1) on the phenotypic expression of LVH in patients with hypertrophic cardiomyopathy (HCM). METHODS: The study population was comprised of 108 genetically independent patients with HCM. Left ventricular mass index (LVMI) and LVH score were determined per published protocols. The genotypes of AGT (M235T, T174M, and G-6A), AT1a, and END1 were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or mutation-specific PCR (MS-PCR). RESULTS: Male patients had higher mean LVMI and LVH score than female patients (146.0 +/- 33.5 vs 129.4 +/- 33.6, p = 0.01 and 6.0 vs 5.0, p = 0.010, respectively). Gender accounted for 4.8% and 5.4% of the variability of LVMI and LVH score, respectively. The END1 genotypes also had a significant influence on LVH scores accounting for 2.9% of their variability (p = 0.042). The median LVH score was greater in patients with the AA and AG genotypes, as compared to patients with the GG genotype (7.0 vs 5.0, p = 0.034). Neither the AGT nor the AT1 genotypes had a significant influence on the expression of LVH. In multivariate regression analysis, END1 and gender accounted for 7.3% of the variability of the LVH score (p = 0.007). CONCLUSIONS: Our results show that gender and the END1 gene modify the phenotypic expression of hypertrophy in patients with HCM.

Adult↗
PubMed1997

Manifestation of Behcet's disease in the digestive tract.

OBJECTIVE: To study the manifestations of Behcet's disease (BD) in the digestive tract and its differential diagnosis from common inflammatory bowel diseases. METHODS: The symptoms and endoscopic, X-ray's or surgical characteristics of 24 cases of Behcet's disease with digestive tract manifestations were analysed. RESULTS: The lesions mainly occurred in tileocecum, and frequently led to hemorrhage that required surgery. The recurrent rate was as high as 77.7%. CONCLUSION: Importance should be attached to early diagnosis of BD of the digestive tract to prevent serious complications.

Abdominal Pain↗
PubMed1997

[Improvement of the pre-hypertensive inherited cardiac dearangements with phenylalanine in essential hypertension].

OBJECTIVE: To assess whether phenylalanine intervention can effectively improve the pre-hypertensive inherited cardiac hypertrophy and systolic dysfunction in young offsprings of patients with essential hypertension (ER). METHODS: Ninty-six normotensive adolescents with hypertensive family history and associated with inherited cardiac hypertrophy, i.e, interventricular, septum (IVST) and (or) left ventricular post wall thickness (PWT) > or = 10.5 mm, were screened according to the normal range criteria of ultrasonic-cardiogram (UCG) obtained previously from 50 normotensive adolescents without hypertensive genetic predisposition. The UCG parameters before and after 3, 6, 9 months of observation were compared between intervention group (Phe 1 g/d 58 subjects) and placebo-control group (placebo 1 g/d, 38 subjects) in 2 separate trials by a double-blind, randomized, cross-over and comparable placebo-control design. RESULTS: The hypertrophy and dilatation of ascending aorta and left heart structure were regressed after intervention, i.g, the changes after 9 months intervention, IVST dropped from 10.9 +/- 1.2 to 9.2 +/- 0.6 mm, PWT from 9.5 +/- 1.0 to 8.6 +/- 0.6 mm, left ventricular mass index from 92 +/- 15 to 70 +/- 11 g/m2; All of the parameters reflecting the systolic function of left ventricle were improved in pooled group of 2 trials. The UCGs after placebo was fundamentally not changed except some sporadic values. The results were similar in 2 separate trials. The improvement after Phe and its return towards that of pre-intervention after stope were remarked at 6 months. CONCLUSION: The inherited cardiac dearrangement seen in adolescents with hypertensive genetic predisposition can be assumed to be the pre-hypertensive changes of EH. It can be reversed by phenylalanine--a natural and essential amino-acid.

Adolescent↗
PubMed1997

[Effects of captopril on the tissue nitric oxide synthase in off spring from treated pregnant SHRs].

OBJECTIVES: To further clarify the anti-hypertensive mechanism of captopril and explore a new method for earlier prevention and treatment of hypertension, we studied the effects on tissue nitric oxide/nitric oxide synthase (NO/NOS) of the descendants of spontaneously hypertensive rats (SHRs) by earlier captopril treatment. METHODS: After the pregnant SHR was treated by captopril (100 mg.kg-1.d-1), the systolic blood pressure (SBP), NOS activity and expression of inducible and constitutive NOS (iNOS and cNOS) in brain cortex, renal cortex, heart ventricle of their descendant were detected by tail-cuff sphyg-momanometer, liquid scintillation and reverse transcription-polymerase chain reaction method respectively. RESULTS: Compared with that of non-treated SHR, SBP of treated SHR was decreased (P < 0.01) and NOS activity of renal cortex, heart ventricle, iNOS expression of brain cortex, cNOS expression of renal cortex, heart ventricle significantly increased (P < 0.05). CONCLUSION: The results suggested that earlier captopril treatment could increase NOS activity and expression in different tissues of SHR, which might be a new anti hypertensiven mechanism.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

[Recovery of motor function of spinal cord with embryonic spinal cord graft in adult rat].

The capacity of embryonic spinal cord tissue in the repair of injured structure of spinal cord has been noted for years. In order to investigate the embryonic spinal cord graft in the repair of motor function of injured spinal cord, the embryonic spinal cord tissue was transplanted to the hemisection cavity in spinal cord in adult rat. One hundred adult Wistar Rats were used to simulate the hemisectional injury of spinal cord by drilling 2-3 mm cavity in lumbar enlargement. Sixty rats were treated with rat embryonic spinal cord tissue grafting while the other forty were chosen as control. The outcome was evaluated according the combined behavioural score (CBS) and motor evoked potential (MEP) in the 1, 2, 4 and 12 weeks. The grafting group was superior to the control as assessed by CBS (P < 0.05), especially within 4 weeks. (P < 0.01). The restoration of the latent peak of early wave(P1, N1) was better in the grafting group, too. This suggested that embryonic spinal cord graft could improve the recovery of motor function of injured spinal cord in adult rat. The effect of the embryonic spinal cord tissue graft might be concerned with its secretion of several kinds of neurotrophic factors, nerve growth factor, nerve transmitted factor, or adjustment of hormone.

Animals↗
PubMed1996

Microemulsion Formation and Phase Behavior of Anionic and Cationic Surfactants with Sodium Dodecyl Sulfate and Cetyltrimethylammonium Bromide

The phase behavior and solubilization of multiphase microemulsions in mixed anionic-cationic surfactant systems were studied for fixed ratios of water-to-oil and surfactant-to-alcohol. In the mixed surfactants (sodium dodecyl sulfate + cetyltrimethylammonium bromide)/heptane/alcohol/water systems, microemulsion and birefringent phases are formed by adjusting the surfactant ratio epsilon and the cationic weight fraction delta. The bicontinuous (or w/o microemulsion) --> birefringent o/w microemulsion transition takes place and microemulsion domain enlarges with increasing epsilon. The optimum surfactant concentration gamma increases and the corresponding optimum delta decreases with increasing epsilon and both of them decrease with increasing the alcohol chain length from butanol to hexanol. The birefringent region shrinks rapidly with increasing alcohol and/or CTAB weight fractions in total surfactant concentration. Conductivity measurements have been performed in the single-phase region of the system containing mixed surfactants and alcohols at 25&deg;C. The conductivity results indicate where a transition takes place and which of these different types of phase structures may be in the single-phase of the system containing anionic-cationic mixed surfactants.

Journal Article↗
PubMed1996

Identification of the pdxK gene that encodes pyridoxine (vitamin B6) kinase in Escherichia coli K-12.

We isolated a miniTn10(Cmr) insertion mutant lacking pyridoxine (PN) kinase and cloned the structural gene, designated pdxK, by complementation. P1 transduction and PCR mapping and DNA sequence analysis showed that pdxK was adjacent to the crr sugar transport gene (53.95 min). Growth properties of pdxK::miniTn10 mutants supported the hypotheses that PN kinase, which also phosphorylates pyridoxal (PL) and pyridoxamine (PM) in vitro, functions solely in the B6-vitamer salvage pathway and that E. coli contains an additional PL kinase. The amino acid sequence of PdxK has signature motifs of the PfkB superfamily of carbohydrate kinases, which includes phosphofructokinases and ribokinases, and suggests that three unidentified ORFs of Salmonella typhimurium, Haemophilus influenzae, and Saccharomyces cerevisiae correspond to PN/PL/PM kinases.

Amino Acid Sequence↗
PubMed1996

The homogenetic estimate for the variance of survival rate.

The homogenetic estimate for the variance of survival rate is proposed based on generalization and reduction between the complement of the empirical distribution function and the Kaplan--Meier or Berkson--Gage estimate. It reduces to the binomial variance estimate when there is no censoring. A Monte Carlo simulation study was carried out under various sample sizes, survival and censoring configurations, number of tied observations, and confidence levels with 2000 replications. It verifies that the commonly employed Greenwood estimate understimates, and the Simon and Lee expression for the Peto estimate strictly overestimates, the variance of survival rate to an extent dependent on the censoring distributions. The conclusions are identical with those of Peto et al. (1977) and Slud et al. (1984). The bias of the homogenetic estimate is less than that of both the Greenwood estimate and the Simon and Lee expression for the Peto estimate. The homogenetic estimate slightly overestimates when there are no ties and becomes unbiased and then slightly underestimates as the number of tied observations increases.

Analysis of Variance↗
PubMed1996

4-Phospho-hydroxy-L-threonine is an obligatory intermediate in pyridoxal 5'-phosphate coenzyme biosynthesis in Escherichia coli K-12.

We show that thrB-encoded homoserine kinase is required for growth of Escherichia coli K-12 pdxB mutants on minimal glucose medium supplemented with 4-hydroxy-L-threonine (synonym, 3-hydroxyhomoserine) or D-glycolaldehyde. This result is consistent with a model in which 4-phospho-hydroxy-L-threonine (synonym, 3-hydroxyhomoserine phosphate), rather than 4-hydroxy-L-threonine, is an obligatory intermediate in pyridoxal 5'-phosphate biosynthesis. Ring closure using 4-phospho-hydroxy-L-threonine as a substrate would lead to formation of pyridoxine 5'-phosphate, and not pyridoxine, as the first B6-vitamer synthesized de novo. These considerations suggest that E. coli pyridoxal/pyridoxamine/pyridoxine kinase is not required for the main de novo pathway of pyridoxal 5'-phosphate biosynthesis, and instead plays a role only in the B6-vitamer salvage pathway.

Acetaldehyde↗
PubMed1996

Dual-electrode detection for capillary electrophoresis/electrochemistry.

The extremely low sample volumes required for capillary electrophoresis and the high sensitivity and selectivity of electrochemical detection make capillary electrophoresis/electrochemistry (CEEC) a very useful method for bioanalysis. In this paper, two types of dual-electrode detectors for CEEC are described. The first employs a ring-disk microelectrode placed in a wall-jet configuration and is used for the selective detection of substances undergoing chemically reversible oxidations. Collection efficiencies obtained for catecholamines with this configuration were between 25 and 35%. The second electrode design consists of two adjacent carbon fibers embedded in an epoxy matrix and is analogous to the parallel dual-electrode configuration used in liquid chromatography/electrochemistry. This configuration can be used to confirm peak identity and purity by operating the electrodes at two different potentials. Alternatively, it is possible to perform simultaneous oxidative and reductive electrochemical detection.

Catecholamines↗
PubMed1996

Neural regulation of coronary vascular resistance: role of nitric oxide in reflex cholinergic coronary vasodilation in normal and pathophysiologic states.

A number of reflexes participate in the control of coronary vascular resistance through activation of the sympathetic or parasympathetic nervous system. Classically, activation of vagal efferent fibers to the heart results in vasodilation due to the release of acetylcholine and activation of muscarinic receptors. Recently, we have found that activation of a number of reflexes in conscious dogs, the Bezold-Jarisch reflex and the carotid chemoreflex in particular, results in cholinergic coronary vasodilation which is blocked by an inhibitor of nitric oxide synthesis, nitro-L-arginine. After the development of pacing-induced heart failure, the cholinergic dilation subsequent to activation of the Bezold-Jarisch or carotid chemoreflex is essentially abolished, since coronary blood vessels no longer produce nitric oxide. In contrast, after brief exercise training, there is a potentiation of Bezold-Jarisch reflex-induced coronary vasodilation since exercise upregulates nitric oxide production by coronary blood vessels. Since the Bezold-Jarisch reflex may be important as a compensatory mechanism during acute myocardial infarction, and the carotid chemoreflex is the acute mechanisms responsible for ameliorating systemic hypoxemia, the role of nitric oxide in reflex cholinergic coronary vasodilation may be essential in the compensatory vascular adjustments evoked by these and other reflexes.

Animals↗
PubMed1996

Experimental study on the early efficacy of excimer laser with adjunctive balloon angioplasty in dog's femoral artery.

The effect of domestically-manufactured excimer laser with adjunctive balloon angioplasty in achieving revascularization and reduction of residual stenosis was assessed. 20 femoral arteries with thrombosis and occlusion from 12 dogs were subject to angiography. At first excimer laser angioplasty was done followed by balloon angioplasty. The diameter and residual stenosis of revascularized vessel were measured. The result showed that 17 out of 20 vessels (85%) were revascularized. The diameter of revascularized vessel by excimer laser were 1.22 +/- 0.14 mm, while residual stenoses were 54% +/- 5%. After adjunctive balloon angioplasty the diameter and residual stenoses were 2.04 +/- 0.16 mm and 20% +/- 7% respectively (P < 0.05 and P < 0.01). Complication in form of vasoperforation occurred in 3/20 vessels (15%). It is concluded that China- manufactured excimer laser angioplasty is effective when used for revascularization. While the reduction of narrowing and residual stenoses was enhanced after adjunction of balloon angioplasty. This method can be employed in treating peripheral occlusive disease effectively and safely.

Angioplasty, Balloon, Laser-Assisted↗
PubMed1996

Free and complexed prostate-specific antigen serum ratios to predict probability of primary prostate cancer and benign prostatic hyperplasia.

OBJECTIVES: Ratios of free to total prostate-specific antigen (f/t PSA ratio) improved differentiation of benign prostatic hyperplasia (BPH) from prostate cancer (CaP). Using sera obtained at least 1 month prior to biopsy-confirmed diagnosis and logistic regression adjusted for disease prevalence, probability curves are constructed to predict the presence of CaP. METHODS: The patient population included 122 (44%) BPH sera and 155 (56%) prostate carcinoma sera collected prior to any therapy. The total PSA range = 2.0-20.0 ng/mL; median age = 69 years. External reference standards for both free and total PSA assays were used to standardize the assays and correct the ratio. Probability curves and tables for cancer incidence were formulated for a subset of the total test population (total PSA range = 2.0-10.0 ng/mL; 98 BPH, 118 CaP patients) by using logistic regression and prior cancer prevalence statistics derived from a published patient screening study. RESULTS: Median f/t PSA ratios were 0.18 and 0.12 in the overall sample and 0.19 and 0.12 in the subset for BPH and CaP, respectively (P = 0.0001). The median total PSA concentrations for BPH and CaP were 5.8 and 6.7 ng/mL when total PSA range = 2.0-20.0 ng/mL and were 4.9 and 5.9 ng/mL when total PSA range = 2.0-10.0, respectively. CONCLUSIONS: Cancer probability curves were constructed to help guide decisions concerning biopsy and other aspects of prostate cancer disease management. Further validation of this approach in another series of patients is necessary and is planned.

Adult↗
PubMed1996

Analysis of a cation-transporting ATPase of Plasmodium falciparum.

We have cloned and characterised one gene, PfATPase4 which encodes a P-type ATPase containing all the primary sequence motifs characteristic of this class of transmembrane ion transporters, and also a fragment of a second P. falciparum P-type ATPase pseudogene (PfATPase5). Analysis of conserved domains and motifs of specific ATPases reveals that PfATPase4 is most analogous to Ca2+ ATPases of the endoplasmic reticulum. The PfATPase4 gene gives rise to a transcript of 8 kb shortly after erythrocyte invasion. Although this mRNA is not detected in later stages, the protein detected immunologically at 190 kDa persists throughout and is detected in free merozoites. Immunofluorescence microscopy reveals that the PfATPase4 protein is concentrated in discrete compartments at the periphery of the parasite. Detailed sequence and structural analyses of these and the other P-type ATPases of P. falciparum described previously, reveals that they comprise an unusual family in several respects. Firstly, the large number of non-homologous genes so far characterised reflects the complexities of ionic regulation in the diverse environments encountered by the parasite. Secondly, the plasmodial P-type ATPase family may be classified both at primary sequence and structural levels into two distinct groups-those typical of P-type ATPases (including PfATPase4) and those which are much more divergent. A third complexity is illustrated by the fact that one of the other members [1] here termed PfATPase6, has an even greater similarity to the sarcoplasmic reticulum Ca2+ ATPases than does PfATPase4, which raises questions about the possible functional relationship between these two members.

Adenosine Triphosphatases↗