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Biomedical subjects

H Gao

Publications and source records attributed to H Gao.

At least 145 records · Page 8Linked to original sources
PubMed1998

Optical design of the NSRL undulator beamline.

The optical design of the NSRL undulator beamline is presented. The NSRL undulator has 29 periods of 9.2 cm that produce a photon energy of 7.7-124 eV with the fundamental and third harmonics at a ring energy of 800 MeV. The beamline consists of a typical Kirkpatrick-Baez prefocusing mirror system, a modified spherical-grating monochromator (SGM) and a refocusing toroidal mirror. The monochromator has two including angles of 148 and 157 degrees with two plane mirrors inserted into the entrance arm in order to cover the wide energy range with high grating diffraction efficiency. Calculation shows that the resolving power of the monochromator can be greater than 5000 with the slits fully opened and 20000 with a 20 micro m opening of the slits. The spot at the sample is about 1.5 (H) mm x 0.5 (V) mm.

Journal Article↗
PubMed1998

Interleukin-6 production by human neutrophils after Fc-receptor cross-linking or exposure to granulocyte colony-stimulating factor.

Polymorphonuclear neutrophils (PMNs) are essential effector cells in host defense and tissue inflammatory responses. These responses may be initiated after cross-linking of cell surface Fc receptors that bind the constant portion of IgG (FcgammaR). We evaluated the effect of cross-linking FcgammaRI or FcgammaRII on interleukin-6 (IL-6) production by purified PMNs from normal donors or from patients being treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF). In PMNs from normal donors, IL-6 mRNA was detected by reverse transcriptase-polymerase chain reaction only after FcgammaRI or FcgammaRII cross-linking. We also found that IL-6 mRNA could be detected in PMNs after either in vitro or in vivo rhG-CSF treatment in the absence of FcgammaR cross-linking. IL-6 protein was found to be produced intracellularly and secreted by PMNs after cross-linking FcgammaRI or FcgammaRII or after rhG-CSF stimulation. Cross-linking FcgammaRI or FcgammaRII on PMNs from patients treated with rhG-CSF resulted in a synergistic increase in IL-6 secretion. Upregulation of IL-6 production by PMNs after rhG-CSF treatment may contribute to a clinical engraftment syndrome that occurs during periods of rapid increase in PMN numbers in patients receiving rhG-CSF.

Gene Expression Regulation↗
PubMed1998

Formation and differentiation of three-dimensional rat marrow stromal cell culture on microcarriers in a rotating-wall vessel.

Using a high aspect ratio vessel (HARV), this study investigated the formation of 3-D rat marrow stromal cell culture on microcarriers and the expression of bone-related biochemical markers under conditions of simulated microgravity. In addition, it calculated the shear stresses imparted on the surface of microcarriers of different densities by the medium fluid in an HARV. Secondary rat marrow stromal cells were cultured on two types of microcarriers, Cytodex-3 beads and modified bioactive glass particles. Examination of cellular morphology by scanning electron microscopy revealed the presence of three-dimensional multicellular aggregates consisting of multiple cell-covered Cytodex-3 microcarriers bridged together. Mineralization was observed in the aggregates. Spherical cell-bead aggregates were observed in an HARV, while cell-bead assemblies were mostly loosely packed in a chain-like or branched structure in a cell bag. The expressions of alkaline phosphatase activity, collagen type I, and osteopontin were shown via the use of histochemical staining, immunolabeling, and confocal scanning electron microscopy. Using a numerical approach, it was found that at a given rotational speed and for a given culture medium, a larger density difference between the microcarrier and the culture medium (e.g., a modified bioactive glass particle) imparted a higher maximum shear stress on the microcarrier.

Alkaline Phosphatase↗
PubMed1998

Separation of aromatic acids, DOPA, and methyl-DOPA by capillary electrophoresis with dendrimers as buffer additives.

Polyamidoamine starburst dendrimers with terminal carboxylate groups are used as a pseudo-stationary phase in electrokinetic chromatography for separating the selected aromatic amino acids phenylalanine, phenylglycine, homophenylalanine, and tyrosine and the catecholamines 3-(3,4-dihydroxyphenyl)alanine and 3-(3,4-dihydroxyphenyl)-2-methylalanine at different pH levels. A significant difference in analyte selectivity is observed between dendrimers of different generations and at different pH levels. At pH 7.0, the utility of the dendrimers for separating these analytes is limited by relatively low selectivity and a noisy baseline. However, good separation and selectivity are obtained with low generation dendrimers (G0.5 and G1.5) at low pH. Strong association of the solute with dendrimers is observed for high generations (G2.5, G3.5, and G5.5).

Biocompatible Materials↗
PubMed1998

A preliminary study of the mental health of young migrant workers in Shenzhen.

The aim of this study is to examine the mental health status of young migrant workers in Shenzhen. Using the Symptoms Check List-90 (SCL-90), Eysenck Personality Questionnaire, Social Support Scale and Mental Health Questionnaire for Laborers, 371 migrant workers who came from inland areas of China and 100 local workers were investigated. The SCL-90 profile of migrant workers was also compared to the SCL-90 norms provided by general people in China. The SCL-90 results showed that the total scores, the average scores of the positive symptoms, the three factor scores of obsessionality, interpersonal sensitivity and phobia in migrant workers were significantly higher than those in the local workers. According to the multivariate analysis, the amount of contribution to mental health, in descending order, was neuroticism, psychological pressure, income, home sickness, marital or love problems, extroversion and introversion, living conditions and social status. The mental health status of young migrant workers in Shenzhen was poorer than that of their local counterparts, as well as people in China on the SCL-90. It is recommended that mental health workers should help migrant workers adjust to the new urban environment by providing psychological counseling and other relevant treatment facilities.

Acculturation↗
PubMed1998

[A study on apoptotic cell death during chemotherapy of patients with acute leukemia].

OBJECTIVE: To investigate whether apoptosis occurs in vivo in patients with acute leukemia during induction chemotherapy and its significance. METHODS: Apoptotic effect on peripheral blood of 20 patients with different types of acute leukemia prior to and during routine chemotherapy was studied by cell morphology, DNA electrophoresis and FCM-DNA analysis. RESULTS: After chemotherapy, with falls in WBC and blast count, no apoptotic cell appeared on smears of peripheral blood, nor did ladder pattern of DNA on electrophoresis and subdiploid peak on FCM. CONCLUSION: Although anticancer drugs have been shown to induce apoptosis in vitro, circulating apoptotic cells are hardly detected probably due to their rapid clearance from the circulation. It is more difficult to study apoptosis in vivo than in vitro.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

[Iodine deficiency and perceptive nerve deafness].

Iodine contents (ICS) in hairs of 381 children with perceptive nerve deafness (PND) and in table salt were determined in Yancheng prefecture and Shuyang county of Jiangsu province, east China from 1995 to 1996. The results showed that the ICS in hairs of deaf children were much lower than that of healthy children (P < 0.01). And the ICS in table salt in these regions were punder the standard content officially published. Presumably, iodine deficiency (ID) in these regions may be one of the major factors causing PND.

Adolescent↗
PubMed1998

[Effect of Sisheng Decoction on repairing function of DNA in mice splenic lymphocytes].

OBJECTIVE: To explore the mechanism of alleviating the side effects of irradiation by Sisheng Decoction (SSD). METHODS: The mice splenic lymphocytes were treated by hydroxylurea to stop the DNA replication in S stage, irradiated by ultraviolet ray (UV) and the 3H TdR was added into the cultural medium. After the lymphocytes were cultured in 37 degrees C for 4 h, the capacity for 3H-TdR in the lymphocytes were tested. The effect of SSD in different content on the cut and patch repair(CPR) of DNA can be inferred by observing the lymphocyte uptake index (LUI) of 3H-TdR. RESULTS: LUI of mice spleen lymphocytes could be increased by pretreating the lymphocytes with SSD for 4 h and then irradiated by UV, but it could not be increased if the lymphocytes were treated by SSD and UV at the same time. CONCLUSION: SSD can alleviate the side effect of irradiation by enhancing the function of CPR-DNA, which need pretreating the lymphocytes with SSD.

Animals↗
PubMed1998

[Effects of electroacupuncture on the expression of estrogen receptor protein and mRNA in rat brain].

In order to show some light on the possible molecular mechanism of the effects of acupuncture on the hypothalamic-pituitary-ovarian axial function, radioimmunoassay (RIA), RNA dot blot and Northern blot, monoclonal antibody immuno-histochemistry and computer image analysis technique were used to study the effects of electroacupuncture (EA) on the blood level of estradiol (E2) and the expression of estrogen receptor protein and mRNA in the ovariectomized rat brain. The results show that ovariectomy induced a decrease of blood E2 level and increase of the expression of estrogen receptor protein and mRNA in the brain. All these effects could be remarkably reversed by previous EA treatment of ovariectomized rats. EA in intact rat, however, had no effects on blood E2 and expression of estrogen receptor. The above results suggest that EA at some effective acupoints may activate the production of body estrogen, resulting in a long term increase or suppression at the level of gene(s) expression and consequent normalization on the dysfunction of hypothalamic-pituitary-ovarian axis.

Animals↗
PubMed1998

[Preliminary study on determination methods of respiratory muscle functions].

Attention has been paid to the research of respiratory muscle functions recently. In this paper some lung function indices concerning respiratory muscle functions, such as maximal inspiratory and expiratory pressure at mouth, inspiratory and expiratory tolerance time, transdiaphragmatic pressure and maximal transdiaphragmatic pressure and diaphragmatic electromyogram etc, were determined in 24 healthy young men and the normal values were obtained. They were important in the study of respiratory muscle functions in hard physical labours, especially in divers, pilots and sportsmen etc. These indices were also useful for evaluating convalescent therapy chronic lung diseases, respiratory muscles training programs or the drug effects on respiratory muscle fatigue etc.

Adult↗
PubMed1998

[Observation on sleep improvement under noise environment by wearing earplugs].

Sleep experiments were done in 6 subjects under 3 conditions. (1) Quiet, background noise level lower than 45dB (A); (2) Noisy with earplugs, ambient noise level 90dB (A); (3) Noisy, ambient noise level 90dB (A), and subjects wearing earplugs. EEG, REM and EMG during sleep were recorded. Sleep latency, times and duration of waking up, sleep rate of each stage and total sleep rate were analyzed. It shows that sleep under noise condition can be improved by wearing earplugs.

Adult↗
PubMed1998

[Mutation induced by space conditions in Escherichia coli strains].

To study the mutagenesis of microorganism under space conditions, three Escherichia coli strains CSH108, A2 and A3, were flown on board the Chinese recoverable satellite (JB1 - B9611020) in Oct . 1996. Three ways of sample boarding were designed . After recovery, survival and frequency of lacI- mutation and Arg+ reversion were determined in the flight strains. The results showed that: E. coli strains could survive after the flight conditions. The lacI- mutation frequency of A3 strain in the biocabin was sixty - seven times that of the ground control, the Arg+ reversion frequency of CSH108 in the lead chamber, was ten times that of the ground control; and among the revertants the mutation frequency of non-sense suppressor increased remarkably. The results indicate that the space conditions may greatly enhance the mutation frequency of certain genes in the microorganism and may provide an effective method for microorganism breeding.

Arginine↗
PubMed1998

[Synthesis and biological activity of 1-(4-alkyloxy)benzyl-1,2,3,4-tetrahydroisoquinolines and related compounds].

In an attempt to search for novel cardiovascular drugs which might act on calcium or potassium channels, on the basis of the previous study of our group, 15 1-(4-alkyloxy)benzyl-1,2,3,4-tetrahydroisoquinolines derivatives were designed and synthesized among which 10 were not reported previously in the literature. Preliminary pharmacological studies showed that most of these compounds exhibited relaxation of rat thoria aorta in vitro. Compound III9 exhibited potent inhibiting action on low KCl(20 mmol.L-1)-induced contraction of rat aorta, and significant protective effect on experimental arrhythmia in rats.

Animals↗
PubMed1998

The effects of increasing exchange volume and frequency on peritoneal dialysis adequacy.

AIM: Peritoneal dialysis adequacy guidelines are generally not met with the standard prescription of continuous ambulatory peritoneal dialysis (CAPD), four 2-liter (1) exchanges daily. The aim of this study is to determine the effects of increasing exchange volume singularly or in combination with frequency on peritoneal dialysis adequacy. PATIENTS AND METHODS: Fourteen stable ESRD patients receiving peritoneal dialysis were evaluated for adequacy and nutritional status between the fourth and sixth months during a six-month baseline period in which the dialysis prescription was four two-liter exchanges daily and during a six-month intervention period in which patients (n = 7) from group 1 were prescribed CAPD four 2.5-liter exchanges daily while patients (n = 7) from group 2 were prescribed continuous cycling peritoneal dialysis (CCPD - 12 l) using four 2.5 liters during the night and a 2-liter wet day. RESULTS: Mean total weekly urea Kt/V (TWKt/V) increased significantly from 1.6 +/- 0.2 to 2.1 +/- 0.2, p <0.01 in group 1, and from 1.6 +/- 0.4 to 2.1 +/- 0.5, p <0.001 in group 2. Mean normal total weekly creatinine clearance increased significantly from 51 +/- 11 to 60 +/- 8 l/1.73 m2, p <0.05 in group 1, and from 45 +/- 6 to 58 +/- 9 l/1.73 m2, p <0.01 in group 2. Serum albumin of almost all patients in the intervention groups were higher than in the baseline groups. Mean serum albumin increased from 3.6 +/- 0.4 to 4.0 +/- 0.4 g/dl, p <0.01 in group 1, and from 3.8 +/- 0.2 to 4.0 +/- 0.4, p <0.05 in group 2. The magnitude of the decrement in BUN and serum creatinine were greater in group 2 than group 1 (p <0.001 and p <0.05, respectively). When the two intervention groups were compared to each other, no significant differences in the delivered dialysis dose or nutritional status were noted. CONCLUSION: In conclusion, it is possible to achieve currently proposed adequacy target by increasing the exchange volume singularly or in combination with frequency in most peritoneal dialysis patients.

Adult↗
PubMed1997

Selective hyperexpression of c-jun oncoprotein by glass fiber- and silica-transformed BALB/c-3T3 cells.

Mining and mineral processing are important industries in the United States. A large number of workers are potentially exposed to silica during mining and to glass fibers during manufacturing. There is a concern regarding lung cancer risk among workers exposed to silica and glass fibers. Our previous studies showed that both glass fibers and silica induced transformation of BALB/c-3T3 cells. In order to explore the relationship between silica and glass fiber-induced cell transformation and oncoprotein expression, the protein products of seven proto-oncogenes (c-K-ras, c-H-ras, c-sis, c-myc, c-myb, c-erb B1 and c-jun) and one tumor suppressor gene (p53) were examined in BALB/c-3T3 cells transformed by glass fibers or silica using immunoblotting with specific monoclonal or polyclonal antibodies. The results showed that all transformants, including eight induced by glass fibers and eight by silica (Min-U-Sil 5), were positive for c-jun protein expression; the level of c-jun protein was elevated 8-21-fold in these transformants. Other protooncogene proteins in transformed cells were either not detectable or not different from non-transformed cells. These results suggest that the overexpression of c-jun is common in BALB/c-3T3 transformed cells induced by glass fibers or silica. It seems, therefore, that the expression of c-jun may play an important role in the transformation process.

3T3 Cells↗
PubMed1997

Ligand-induced down-regulation of Trk messenger RNA, protein and tyrosine phosphorylation in rat cortical neurons.

Chronic exposure of brain neurons to nerve growth factor in vitro and in vivo results in increased levels of the nerve growth factor receptor TrkA. In contrast, in the present study, we have found that chronic exposure of rat embryonic cortical neurons to brain-derived neurotrophic factor (BDNF) leads to a pronounced reduction of the levels of protein and messenger RNA for the full-length but not the truncated BDNF receptor TrkB. Similar effects were observed with the other TrkB ligands neurotrophin-3 and neurotrophin-4/5. After pretreatment with BDNF, neurotrophin-3 or neurotrophin-4/5, subsequent tyrosine phosphorylation responses of the remaining Trks to the same factors were greatly reduced. Three days exposure of rat embryonic cortical neurons to BDNF induced an absolute refractory period of several hours, with no subsequent response to the same factor. Similar but less pronounced refractory effects were observed with neurotrophin-3 and neurotrophin-4/5. Our results suggest a negative regulatory effect of BDNF and other TrkB ligands on TrkB receptors. Down-regulation of the TrkB response by its ligands might play a role in the control of BDNF action during early development, when BDNF levels significantly increase. Our findings are also of potential clinical relevance, since the possibility of ligand-induced down-regulation of the receptor response needs to be addressed when considering BDNF or other neurotrophins for the therapy of neurodegeneration.

Animals↗