Biomedical subjects

H Gu

Publications and source records attributed to H Gu.

At least 109 records · Page 6Linked to original sources

PubMed1998

[Effects of static magnetic fields on free radical metabolism of human body].

The effects of static magnetic fields at 150 to 155 mT on the activities of superoxide dismutase (SOD) and the contents of maglonydiadehyde (MDA) in the serum and the activities of glutathione peroxidase (GSH-Px) in the whole blood were observed in the healthy volunteers. The results showed that the activities of SOD and GSH-Px were significantly increased, and the content of MDA was significantly decreased in short term at the observed magnitude of static magnetic fields. The results suggest that the function of the free radical metabolism of human body could be improved by static magnetic fields at that magnitude.

Adolescent↗

PubMed1998

[Distal spleno-caval shunt in 66 patients with portal hypertension].

OBJECTIVE: To evaluate the long-term results and operative experience of distal splenocaval shunt. METHOD: 66 patients with portal hypertension were treated by distal spleno-caval shunt. Of these patients 57 were males and 9 females with a mean age of 39 years. All the patients were followed up. RESULT: The operative mortality rate was 7.58%. Only 5 patients experienced recurrent bleeding (7.58%). None of the patients had clinical hepatic encephalopathy. Five-year survival rate was 70.45%. CONCLUSION: Distal splenocaval shunt is suitable for portal hypertension patients with hepatopetal portal flow.

Adult↗

PubMed1998

[Establishment of germinal cell line of Echinococcus granulosus].

AIM: To establish a cell line of Echinococcus granulosus. METHODS: The proliferating membranes striped from liver cysts in a naturally infected sheep from Urumq were released to monodispersed germinal cells by grinding. The germinal cells were cultivated in the RPMI 1640 medium supplemented with 10%-20% calf serum on collagen-coated 24-well culture plate alternately from passage 1 to passage 14, and then continued. The morphological feature and growth situation were observed by light microscopy. The cultured cells were inoculated into BALB/c mice to identify the infectivity. ELISA was used to determine the immunogenicity of the cells. RESULTS: The germinal cells have been cultivated continuously up to passage 75. The subcultured cells were circular in shape with smooth surface and had the tendency to form syncytia and tissue-like masses. The cells from this cell line could be stored for at least 15 days in refrigerator at 4 degrees C and 10 months in liquid nitrogen. No cyst materials were detected in the mice inoculated with cells. The antigens from cell line could react with positive sera from mice infected with protoscoleces and sera against secreted antigens of cyst membrane, soluble antigens from cyst membrane, soluble antigens from protoscoleces and SHF. CONCLUSION: A germinal cell line of Echinococcus granulosus was successfully established.

Animals↗

PubMed1998

Converting an integrated hospital formulary into an object-oriented database representation.

Controlled Medical Vocabularies (CMVs) have proven to be extremely useful in their support of the tasks of information sharing and integration, communication among various software applications, and decision support. Modeling a CMV as an Object-Oriented Database (OODB) provides additional benefits such as increased support for vocabulary comprehension and flexible access. In this paper, we describe the process of modeling and converting an existing integrated hospital formulary (i.e., set of pharmacological concepts) into an equivalent OODB representation, which, in general, we refer to as an Object-Oriented Healthcare Vocabulary Repository (OOHVR). The source for our example OOHVR is a formulary provided by the Connecticut Healthcare Research and Education Foundation (CHREF). Utilizing this source formulary together with the semantic hierarchy composed of major and minor drug classes defined as part of the National Drug Code (NDC) directory, we constructed a CMV that was eventually converted into its OOHVR form (the CHREF-OOHVR). The actual conversion step was carried out automatically by a program, called the OOHVR Generator, that we have developed. At present, the CHREF-OOHVR is running on top of ONTOS, a commercial OODB management system, and is accessible on the Web.

Databases as Topic↗

PubMed1997

Contrasting roles for symmetrically disposed beta-turns in the folding of a small protein.

To investigate the role of turns in protein folding, we have characterized the effects of combinatorial and site-directed mutations in the two beta-turns of peptostreptococcal protein L on folding thermodynamics and kinetics. Sequences of folded variants recovered from combinatorial libraries using a phase display selection method were considerably more variable in the second turn than in the first turn. These combinatorial mutants as well as strategically placed point mutants in the two turns had a similar range of thermodynamic stabilities, but strikingly different folding kinetics. A glycine to alanine substitution in the second beta-turn increased the rate of unfolding more than tenfold but had little effect on the rate of folding, while mutation of a symmetrically disposed glycine residue in the first turn had little effect on unfolding but slowed the rate of folding nearly tenfold. These results demonstrate that the role of beta-turns in protein folding is strongly context-dependent, and suggests that the first turn is formed and the second turn disrupted in the folding transition state.

Bacterial Proteins↗

PubMed1997

Cardioprotective efficacy of ischemic preconditioning on long-term myocardial ischemia.

This study was designed to assess whether the protective effect of ischemic preconditioning can be adapted for myocardium undergoing 6 h of no-flow ischemia. Twelve isolated rat hearts were either perfused with oxygen-bicarbonated Krebs-Henseleit buffer in the Langendorff mode for 35 min (n=6), or perfused in the same way for 20 min, following 5 min of global normothermic ischemia and 100 min of buffer-perfusion (n=6). The 12 hearts were then preserved for 6 h in HTK solution at 4 degrees C, followed by 30 min of reperfusion. Recovery of cardiac function, metabolic activity and intracellular free calcium concentration were compared between the two groups. After 6 h ischemia, the hearts that underwent preconditioning showed better recovery of left ventricular developed pressure (P<0.01), a lower end-diastolic pressure level (P<0.05), less creatine kinase leakage and a lower calcium concentration. There was no statistical difference in the recovery rate of coronary flow and leakage rate of LDH between the two groups. In conclusion, this experiment demonstrates that ischemic preconditioning improved myocardial functional recovery after 6 h of hypothermic ischemic preservation in the isolated rat heart. Preconditioning might be a potential mechanism for preserving the heart against long-term ischemia/reperfusion injury.

Animals↗

PubMed1997

An interleukin 4 (IL-4)-independent pathway for CD4+ T cell IL-4 production is revealed in IL-4 receptor-deficient mice.

IL-4 receptor alpha chain (IL-4Ralpha)-deficient mice were generated by gene-targeting in BALB/c embryonic stem cells. Mutant mice showed a loss of IL-4 signal transduction and functional activity. The lack of IL-4Ralpha resulted in markedly diminished, but not absent, TH2 responses after infection with the helminthic parasite Nippostrongylus brasiliensis. CD4+, CD62L-high, and CD62L-low T cell populations from uninfected IL-4Ralpha-/- mice were isolated by cell sorting. Upon primary stimulation by T cell receptor cross-linkage, the CD62L-low, but not the CD62L-high, cells secreted considerable amounts of IL-4, which was strikingly enhanced upon 4-day culture with anti-CD3 in the presence or absence of IL-4. CD62L-low cells isolated from IL-4Ralpha-/-, beta2-microglobulin-/- double homozygous mice produced less IL-4 than did either IL-4Ralpha-/- or wild-type mice. These results indicate that an IL-4-independent, beta2-microglobulin-dependent pathway exists through which the CD62L-low CD4+ population has acquired IL-4-producing capacity in vivo, strongly suggesting that these cells are NK T cells.

Animals↗

PubMed1997

1-Acetyl-3-hydroxyadamantane and 1-carboxy-3-hydroxyadamantane.

The crystal structures of the adamantane derivatives, 1-acetyl-3-adamantanol, C12H18O2, (4), and 3-hydroxyadamantane-1-carboxylic acid, C11H16O3, (5), have been determined by X-ray diffraction. Both structures show extensive intermolecular hydrogen bonding involving the hydroxyl and acetyl groups in compound (4), and the hydroxyl and carboxyl groups in compound (5).

Adamantane↗

PubMed1997

Characterization of two SHP-2-associated binding proteins and potential substrates in hematopoietic cells.

Multiple studies have demonstrated an important role for the Src homology 2-containing tyrosine phosphatase 2 (SHP-2) in receptor tyrosine kinase-regulated cell proliferation and differentiation. Recent studies have identified potential SHP-2 substrates which mediate these effects. SHP-2 also is implicated in several cytokine receptor signaling pathways and in Bcr-Abl transformation. However, its precise role and targets in normal and abnormal hematopoietic cells remain to be determined. We identified two novel tyrosyl-phosphorylated proteins associated with SHP-2 in hematopoietic cells. The first, a 97-kDa cytosolic protein (p97), associates inducibly with SHP-2 upon cytokine stimulation and constitutively in Bcr-Abl-transformed cells. In contrast, p135, a 135-kDa transmembrane glycoprotein, forms a distinct complex with SHP-2, independent of cytokine stimulation or Bcr-Abl transformation. Far Western analysis reveals that SHP-2, via its Src homology 2 domains, can interact directly with either protein. In vitro dephosphorylation experiments, as well as transient transfection studies using wild type and mutant SHP-2 constructs, suggest that p97 and p135 also are SHP-2 substrates. Our results indicate that SHP-2 forms at least two separate complexes in hematopoietic cells and point to new potential SHP-2 targets.

Animals↗

PubMed1997

Kinetics of folding of the IgG binding domain of peptostreptococcal protein L.

The kinetics of folding of a tryptophan containing mutant of the IgG binding domain of protein L were characterized using stopped-flow circular dichroism, stopped-flow fluorescence, and HD exchange coupled with high-resolution mass spectrometry. Both the thermodynamics and kinetics of folding fit well to a simple two-state model: (1) Guanidine induced equilibrium denaturation transitions measured by fluorescence and circular dichroism were virtually superimposable. (2) The kinetics of folding/unfolding were single exponential under all conditions examined, and the rate constants obtained using all probes were similar. (3) Mass spectra from pulsed HD exchange refolding experiments showed that a species with very little protection from exchange is converted to a fully protected species (the native state) at a rate very similar to that of the overall change in tryptophan fluorescence; no intervening partially protected species were observed. (4) Rate constants (in H2O) and m values for folding and unfolding determined by fitting observed relaxation rates obtained over a broad range of denaturant concentrations to a two-state model were consistent with the equilibrium parameters deltaG and m: -RT ln(k(u)/k(f))/deltaG(U)H2O = 1.02; (m(u) + m(f))/m = 1.08. In contrast to results with a number of other proteins, there was no deviation from linearity in plots of ln k(obs) versus guanidine at low guanidine concentrations, both in the presence and absence of 0.4 M Na2SO4, suggesting that significantly stabilized intermediates do not accumulate during folding. Although all of the change in fluorescence signal during folding in phosphate buffer was accounted for by the simple exponential describing the overall folding reaction, fluorescence-quenching experiments using sodium iodide revealed a small reduction in the extent of quenching of the protein within the first two milliseconds after initiation of refolding in low concentrations of guanidine, suggesting a partial collapse of the unfolded chain may occur under these conditions. Comparison with results on the structurally and functionally similar IgG binding domain of streptococcal protein G show intriguing differences in the folding of the two proteins.

Antigen-Antibody Reactions↗

PubMed1997

Effect of acidosis on contraction, intracellular pH, and calcium in the newborn and adult rabbit aorta.

This study investigated the effect of acidosis on intracellular pH (pHi), intracellular calcium concentration ([Ca]i), and vascular contraction in the aorta of the newborn and adult rabbit. Isometric tension, pHi, and [Ca]i were measured in an isolated ring preparation. After the vascular contraction was induced with 50mM KC1, the effect of respiratory acidosis produced by elevation of PCO2 was studied. Respiratory acidosis caused a transient depression followed by a recovery of contractile tension. The decrease in developed tension was greater in the newborn than in the adult. The decrease in pHi during acidosis was similar in the two age groups. [Ca]i increased during acidosis and the increase was greater in the newborn than in the adult. These data show that the vasorelaxant effect of acidosis in the newborn aorta is greater than that in the adult aorta. The greater vasodilation in the newborn cannot be explained by the difference in pHi or [Ca]i.

Acidosis, Respiratory↗

PubMed1997

Mice lacking a functional chk gene have no apparent defects in the hematopoietic system.

Non-receptor tyrosine kinase Chk has been implicated in hematopoietic development. To study the function of Chk in vivo, we have generated chk-deficient mice using gene targeting. Overall development of mice homozygous for this mutation was apparently normal. Blood counts, FACS analysis of hematopoietic cell populations, CFU-C and CAFC assays showed no significant difference between wild type and mutant animals. Thus, the dispensability of Chk for mouse development and hematopoiesis suggests that its function may be redundant in vivo, and most likely be compensated by activity of a closely related protein tyrosine kinase Csk.

Animals↗

PubMed1997

Developmental changes in the contractile system of the mesenteric small artery of rabbit.

This study investigated developmental changes in the contractile system of the mesenteric small arteries of the rabbit. Arteries about 1 mm in length and 100-250 microns in internal diameter were dissected out from the mesenteric bed of the fetus (29 d of gestation), newborn (3-5 d old), and adult rabbit. Vascular contraction was induced by high KCl concentration, and contractile force was measured using a tension transducer. The sensitivity of vascular contraction to high KCl was similar in the three age groups. To determine the role of Ca influx across the sarcolemma in vascular contraction, the vasorelaxant effect of diltiazem was studied in the artery precontracted with high KCl concentration. The vasorelaxant effect of diltiazem in the fetus and newborn was less than in the adult. To estimate the size of the intracellular Ca pool, caffeine-induced and noradrenaline-induced contraction were measured in the Ca- and Na-free solution. In the fetus and newborn, both the caffeine-induced contraction and noradrenaline-induced contraction were greater than in the adult. The ultrastructural study showed that the endoplasmic reticulum was abundant in the fetus and newborn, and it was scarce in the adult. These data indicate that the dependency of vascular contraction on Ca influx across the sarcolemma increases and the intracellular Ca store decreases with development in the mesenteric resistance arteries.

Aging↗

PubMed1997

Developmental changes in the effect of acidosis on contraction, intracellular pH, and calcium in the rabbit mesenteric small artery.

The purpose of the present study was to determine developmental changes in the effect of respiratory acidosis on vascular smooth muscle contraction. Vessel diameter, intracellular pH (pHi), and calcium concentration ([Ca]i) were measured in a cannulated preparation of the small mesenteric artery of newborn and adult rabbits. In the artery precontracted by high KCl, acidosis caused a vasorelaxation both in the newborn and the adult; the vasorelaxation was greater in the newborn than in the adult. The fura-2 fluorescence ratio, an indicator of [Ca]i, decreased transiently during acidosis and the decrease was similar in the two age groups. In the artery precontracted by norepinephrine, acidosis caused a transient vasoconstriction in the adult and a vasorelaxation in the newborn. In these vessels, the fura-2 fluorescence ratio increased transiently during acidosis; the increase was similar in the two groups. Upon induction of acidosis, pHi fell rapidly in the artery precontracted by norepinephrine or high KCl, and the depression of pHi was similar in the two groups. In the skinned smooth muscle preparation, a tension-[Ca] relationship curve at pH 7.1 was not significantly different from that at pH 6.8 in the adult. In the newborn, the tension-[Ca] curve at pH 6.8 was shifted to the right, compared with that at pH 7.1. These data suggest that the vasorelaxant effect of respiratory acidosis in the premature vessel is greater than in the adult. The greater vasorelaxation in the newborn cannot be explained by the age-related difference in pHi or [Ca]i during acidosis. The greater sensitivity of myofibrils to low pHi in the newborn may, at least in part, be responsible for the greater vasorelaxation in this age group.

Acidosis, Respiratory↗

PubMed1997

[Observation on electrogastrogram changes during parallel swing stimulation].

In order to study the relationship between cutaneous electrogastrogram (EGG) and nausea syndrome of the motion sickness, power spectrum analysis is used to analyze EGG recorded during motion sickness evoked by the parallel swing in 32 healthy men. 20 subjects showed a shift of Period Dominant Frequency (PDF) of EGG from Three CPM (2.40-3.70cpm) to Tachygastria (3.70-10.00cpm). PDF, the percentage of power of Tachygastria wave and Dominant Frequency Instability Coefficient significantly increased (P < 0.01). The incidences of nausea syndrome was obvious at the moment after swing. The result showed that EGG may be used for testing nausea symptoms of motion sickness.

Electrodiagnosis↗

PubMed1997

[Comparison of evaluation methods on changes of facial microcirculation during induction of motion sickness].

In order to increase the accuracy of motion sickness grading criteria, infrared thermography and Laser Doppler microcirculation blood-flow detector were used in 60 healthy male individuals: before, immediately, and 20 min after paralleled-swing stimulation. Facial skin temperature and microvessel blood-flow were recorded. The results showed that facial skin temperature and blood flow in facial microvessels fell together with the appearance of pallor. However, the degree of pallor observed with naked eye was inconsistent with that found by thermography or facial blood flow. It suggests that the accuracy of grading might be improved with the use of thermography or measurement of facial microvessel blood flow.

Face↗

PubMed1997

[Studies on determination of p-aminophenol and its related compounds prepared with catalytic hydrogenation by reversed-phase high performance liquid chromatography].

Catalytic hydrogenation of nitrobenzene with supported palladium catalyst is a new method to produce p-aminophenol. p-Aminophenol, aniline and 4,4'-diaminodiphenyl ether obtained from this method were determined by reversed phase high performance liquid chromatography. The factors, e.g., concentration of methanol, pH and ionic strength which could affect separation efficiency were studied. UV spectra of p-aminophenol, aniline and 4,4'-diaminodiphenyl ether were recorded. Good separation was performed by using a 100 mm x 4.6 mm column with 5 microm Hypersil ODS, a mixture of 60% aqueous 8.0 mmol/L KH2PO4 buffered to 6.5 with 4.0 mmol/L Na2HPO4 and 40% methanol as mobile phase at a flow rate of 1.0 mL/min, and UV spectrophotometric detector at 232 nm wavelength. The calibration curves of p-aminophenol, aniline and 4,4'-diaminodiphenyl ether have good linearity over concentration range of 5-250, 5-150 and 0.2-120 mg/L, respectively. Minimum detectable limits at a signal-to-noise ratio of 2 were 0.1, 0.6 and 0.6 ng. This method has been applied to analysis of the reaction products of ultrasonic catalytic hydrogenation and industrial samples with good results and reproducibility.

Aminophenols↗

PubMed1997

[Study of the effects of pulse magnetic fields on hemorrheology of human body].

The results show that middle shear specific viscosity and reductive viscosity (P<0.05), low shear specific viscosity and reductive viscosity of whole blood (P<0.01) decreased significantly in experimental group after 9-day of pulse magnetic fields, comparing with control group, high shear specific viscosity, low shear reductive viscosity (P<0.05) and middle and low shear specific viscosity (P<0.01) of whole blood in experimental group were lower after exposed than before exposed to pulse magnetic fields. The results suggest that the pulse magnetic fields may reduce specific and reductive viscosity of whole blood in human body.

Blood Viscosity↗