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F Gao

Publications and source records attributed to F Gao.

At least 145 records · Page 8Linked to original sources
PubMed1999

Effect of aging on the negative chronotropic and anti-beta-adrenergic actions of adenosine in the rat heart.

The effect of aging on the antiadrenergic actions of adenosine was studied in vitro and in vivo by using adult (6-month-old) and old (24-month-old) male Fischer 344 rats. In anesthetized animals, adenosine (0.01-0.1 micromol/kg), given as a rapid bolus into the right atrium, exerted a negative chronotropic effect manifested by a dose-dependent transient prolongation of sinus cycle length (SCL). This effect was similar in both age groups (n = 6, each; i.e., the percentage maximal prolongation of SCL (%deltaSCL) ranged from 12 +/- 2% to 63 +/-14% in the adult and from 20 +/- 7% to 57 +/- 15% in the old rats. In the presence of isoproterenol (0.2 microg/kg/min), the negative chronotropic action of adenosine was potentiated in the adult rats much more than in the old rats [i.e., %deltaSCL ranged from 60 +/- 28% to 183 +/- 48% vs. 40 +/- 12% to 70 +/- 13%, respectively (p < 0.05, adult vs. old)]. In the isolated perfused hearts, isoproterenol (1 microM for 1 min) exerted similar chronotropic and inotropic effects in adult (n = 9) and old hearts [n = 6; i.e., heart rate, left ventricular pressure (LVP), and LVdp/dt increased by 56 +/- 3%, 17 +/- 1%, and 37 +/- 2%, and 57 +/- 2%, 17 +/- 1%, and 35 +/- 3%, respectively, in the absence of, and by 27 +/- 2%, 7 +/- 1%, and 19 +/- 2% and 41 +/- 3%, 12 +/- 1%, and 25 +/-2% in the presence of adenosine (5 microM for 1 min)]. Adenosine administration after isoproterenol caused only an insignificant increase in coronary blood flow. Finally, the adenosine attenuation of either isoproterenol- or forskolin-induced production of 3',5'-cyclic adenosine monophosphate (cAMP) was significantly less in atrial membranes isolated from old versus adult rats (n = 6, each). It was concluded that in the old Fischer 344 rat hearts, the antiadrenergic action of adenosine is attenuated as compared with its action in adult rat hearts.

Adenosine↗
PubMed1999

Detection of phylogenetically diverse human immunodeficiency virus type 1 groups M and O from plasma by using highly sensitive and specific generic primers.

The high degree of genetic diversity within human immunodeficiency virus type 1 (HIV-1), which includes two major groups, M (major) and O (outlier), and various env subtypes within group M (subtypes A to J), has made designing assays that will detect all known HIV-1 strains difficult. We have developed a generic primer set based on the conserved immunodominant region of transmembrane protein gp41 that can reliably amplify as few as 10 copies/PCR of viral DNA from near-full-length clones representing group M subtypes A to H (subtypes I and J were not available). The assay is highly sensitive in detecting plasma viral RNA from HIV-1 strains of diverse geographic origins representing different subtypes of HIV-1 group M as well as HIV-1 group O. Of the 253 group M plasma specimens (subtypes A, 68 specimens; B, 71; C, 19; D, 27; E, 23; F, 33; and G, 12), 250 (98.8%) were amplified by using the gp41 M/O primer set. More importantly, all 32 (100%) group O plasma samples were also amplified with these primers. In vitro spiking experiments further revealed that the assay could reliably detect as few as 25 copies/ml of viral RNA and gave positive signals in HIV-1-seropositive specimens with plasma copy numbers below the limits of detection by all commercially available viral load assays. In addition, analysis of five seroconversion panels indicated that the assay is highly sensitive for early detection of plasma viremia during the "window period." Thus, the highly sensitive assay will be useful for early detection of HIV-1 in clinical specimens from all known HIV-1 infections, regardless of their genotypes and geographic origins.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Effects of inhaled nitric oxide and high-frequency ventilation in rabbits with meconium aspiration.

AIM: To evaluate effects of inhaled nitric oxide (iNO) in experimental meconium aspiration treated with high-frequency (HFV) or conventional mechanical ventilation (CMV). Ventilated adult rabbits had meconium instilled intratracheally resulting in respiratory failure as evidenced by more than 50% reduction of dynamic lung compliance (Cdyn) and increase in mean oxygenation index (OI) from 1 to 16. The animals were then allocated to 2 groups treated without (control) or with iNO at 20 ppm (NO). In each group the animals were initially ventilated with CMV or HFV mode for 3 h and then in a crossover fashion with HFV or CMV for another 3 h (CMV-->HFV, HFV-->CMV), respectively. In the first 3 h of treatment, the animals subjected to HFV-CMV in the control, and those with both HFV-CMV and CMV-HFV in the NO group had significantly reduced OI. In the subsequent 3 h, the animals in the control group with CMV-HFV did not improve in OI and those with HFV-CMV had deteriorated. In the NO group with both CMV-HFV and HFV-CMV moderate improvement of OI was observed. Platelet aggregation capability and counts were significantly decreased and bleeding time prolonged in animals receiving iNO treatment. These results suggest that both HFV alone and a combined treatment of iNO with either CMV or HFV are more effective in improving blood oxygenation than that of CMV in this animal model. The influence of iNO on platelet aggregation should be considered.

Administration, Inhalation↗
PubMed1999

[Long-term effect of treating patients with precancerous lesions of the esophagus].

OBJECTIVE: To report long term therapeutic effect in patients with esophageal pre-cancerous lesions in high-risk area of esophageal cancer. METHODS: The therapeutic trial enrolled 2,531 cases of severe dysplasia and 3,393 cases of mild dysplasia. A 2-arm randomized, placebo-controlled design was used in which the participants received Zeng Sheng Ping (ZSP, an herbal composite), retinamide or placebo for cases with severe dysplasia and riboflavin or placebo for those with mild dysplasia. RESULTS: Treatment with ZSP and retinamide decreased malignant transformation rate of severe dysplasia by 52.2% and 43.2%, respectively after 5 years of treatment. When the treatment had been discontinued for 4 years, the rate of malignat transformation was decreased by 42.1% and 38.2% respectively, which remained significantly higher than that of the placebo-treated control. Riboflavin treatment was continued for 9 years. At the end of 5-year medication, the malignant transformation rate decreased by 34.8%, which was not significantly different from that of the placebo control. When the treatment was continued up to 9 years, the rate was further decreased to 37.0%, which became statistically significant. CONCLUSION: ZSP, retinamide and riboflavin treatment can effectively prevent esophageal dysplasia from transforming into carcinoma.

Adult↗
PubMed1999

[Slow transit constipation treated by surgery: analysis of 17 cases].

OBJECTIVE: To explore the operative indications, prognosis, and possible pathogenic factors of slow transit constipation (STC). METHODS: 17 cases with STC who had undergone colectomy were analysed. RESULTS: Bowel movement frequency was once per 4 to 14 days in all of the patients, who had had long-term laxative abuse. Delayed colonic transit was demonstrated in all patients, 82.4% of them were accompanied by outlet obstructive constipation (OOC) and 50% showed abnormal sex hormones. Reduced numbers of argyrophilic neurons and vacuolar degeneration of axons were demonstrated at the myenteric plexus pathologically. Three patients had adhesive ileus postoperatively and one patient suffered from difficult evacuation again 5 years after the operation. CONCLUSIONS: Colectomy is highly effective in alleviating symptoms in patients with STC, and pelvic floor disorder of OOC should be treated simultaneously.

Adolescent↗
PubMed1999

[Detection of telomerase activity in gastric cancer and adjacent tissues].

OBJECTIVE: To study the telomerase activity in chinese gastric cancer and their adjacent tissues and to explore the possibility of telomerase as a tumor biological marker. METHODS: Telomerase activity was analyzed in 42 primary gastric cancers and their adjacent tissues and 1 benign gastric lesion by a PCR-based telomerase repeat amplification protocol assay. RESULTS: The result showed 88.1% (37/42) gastric cancerous specimens displayed telomerase activity. However, only 2 of 42 tissue samples adjacent to the gastric cancer showed telomerase activity. However our results indicated that 1 benign gastric lesion sample expressed telomerase activity. CONCLUSIONS: The results indicated that the detection of telomerase activity might be a useful method in the diagnosis of gastric cancer.

Humans↗
PubMed1999

[Clinical significance of detecting telomerase activity in ascites cells from patients with ovarian carcinoma].

OBJECTIVE: The purpose was to investigate the clinical significance of telomerase activity for tumor diagnosis in ascites cells from patients with ovarian carcinoma. METHODS: Thirty ascites specimens from patients with ovarian tumor were examined for telomerase activity by PCR-based TRAP (telomeric repeat amplification protocol) method, and the result of detection was compared with the cytological diagnosis. RESULTS: Telomerase activity was detected in ascites cells from patients with ovarian tumor in 19 of the 20 cytologic-possitive specimens and in 3 of the 7 cytologic-negative specimens and in all the 3 cytologic-suspicious specimens. The positive rate in 30 ascites samples by cytological examination and by the detection of telomerase activity was 66.67% (20/30), and 83.33% (25/30), respectively. CONCLUSIONS: The result suggested that measuring telomerase activity in ascites cells would be helpful to cytological examination in diagnosis of patients with ovarian carcinoma.

Ascites↗
PubMed1999

[The development and clinical application of a multipurpose neuroendoscope].

The multipurpose rigid neuroendoscope MGE-4 has been developed with the application of the self-focussing lens technology. We have been using it to examine and treat 10 neurosurgical patients who suffered from tumours, hydrocephalus, intracerebral haematomas of head injury and hypertensive cerebral haemorrhage. The short-term effect was satisfactory and there was no operative complications. It is considered that Model MGE-4 with the accessories can be used safely for the brain functional subcortical lesion or the deep-seated cystic lesions and haematomas.

Adult↗
PubMed1998

At least four loci and gender are associated with susceptibility to the chemical induction of lung adenomas in A/J x BALB/c mice.

Four putative quantitative trait loci (QTLs) that influence susceptibility to the induction of lung adenomas by urethane in an F2 cross between A/J and BALB/cOlaHsd have been mapped. Following microsatellite typing of mice with resistant and susceptible phenotypes at 97 microsatellite marker loci, a major locus was identified on chromosome 18 with a lod score of 15. This was responsible for an 8- to 10-fold increase in tumor multiplicity in males and females, respectively, having the AA and CC genotypes at the D18Mit188 marker locus. It mapped close to Dcc (deleted in colorectal cancer). A locus on chromosome 4 (lod score 6.5) had the resistant allele in strain A/J and the susceptible allele in BALB/c, with a 14-fold difference in tumor multiplicity between mice of the AA and CC genotypes. This mapped close to the Cdkn2a (cyclin-dependent kinase inhibitor 2A) locus, which is commonly deleted in mouse lung tumors. Two loci with smaller effects (lod scores 3.03 and 3.25) were identified on chromosomes 1 and 11. There was also significant sexual dimorphism in tumor multiplicity both among 151 F2 hybrids and among 52 mice resulting from a backcross to strain A/J, with males having higher tumor counts than females.

Adenoma↗
PubMed1998

Effects of mechano-gated cation channel blockers on Xenopus oocyte growth and development.

The putative role(s) of a mechanically gated (MG) cation channel in Xenopus oocyte growth, maturation, fertilization and embryogenesis has been examined. Using a pharmacological approach, we have tested the effects of the MG channel blockers, gadolinium, gentamicin and amiloride on the above developmental events. Our results indicate that oocyte maturation, fertilization and early embryogenesis (up to the free-swimming stage 45) can proceed normally in the presence of concentrations of agents that either completely abolish (i.e., > or = 10 microM Gd3+) or partially block (i.e., 1 mM gentamicin) single MG channel activity as measured by patch-clamp recording. However, we also find that higher concentrations of Gd3+ (> or = 50 microM) can lead to an increased percentage (> 20%) of axis-perturbed embryos compared with control (< 1%) and that amiloride (0.5 mM) reduces the success of fertilization (from 100% to < 50%) and increases mortality (by approximately 75%) in developing embryos. Furthermore, we find that all three agents inhibit oocyte growth in vitro. However, their order of effectiveness (amiloride > gentamicin > Gd3+) is opposite to their order for blocking MG channels (Gd3+ >> gentamicin > amiloride). These discrepancies indicated that the drugs effects occur by mechanisms other than, or in addition to, MG channel block. Our results provide no compelling evidence for the idea that MG channel activity is critical for development in Xenopus. This could mean that there are other mechanisms in the oocyte that can compensate when MG channel activity is blocked or that the protein that forms the channel can undergo additional interactions that result in a function insensitive to MG channel blockers.

Amiloride↗
PubMed1998

Q-band resonance Raman spectra of oxidized and reduced mitochondrial bc1 complexes.

Recently published crystallographic studies of mitochondrial bc1 complexes have stimulated renewed interest in the active site architecture of these important integral membrane proteins. We present resonance Raman spectra obtained via variable excitation within the heme Q-band from samples poised in several different net redox states. Appropriate subtraction and polarization analysis allows the vibrational behavior of the individual heme bL,bH, and c1 sites to be assessed. The spectra of the b hemes are particularly noteworthy. They exhibit evidence for a protonation equilibrium involving heme axial ligands and reveal a marked structural heterogeneity at the heme bH site that most likely involves nonplanar distortions of the macrocycle. The possible implications of these findings for heme functionality are discussed.

Animals↗
PubMed1998

Postsynaptic responses of horizontal cells in the tiger salamander retina are mediated by AMPA-preferring receptors.

The postsynaptic responses of sign-preserving second-order retinal neurons (horizontal cells (HCs) and off-bipolar cells) are mediated by CNQX-sensitive AMPA/KA glutamate receptors. In this study we used receptor-specific allosteric regulators of desensitization and selected antagonists to determine the glutamate receptor subtypes in tiger salamander horizontal cells. Two approaches were employed in this study. The first was to measure postsynaptic currents induced by exogenously applied glutamate under voltage clamp conditions in living retinal slices; and the second was to record voltage responses controlled by endogenous glutamate released from photoreceptors in whole retinas. Application of 100 microM cyclothiazide (a specific AMPA receptor desensitization blocker) enhanced the glutamate-induced current by about 5 fold. In contrast, 300 microgram ml-1 Co nA (a specific kainate receptor desensitization blocker), had no effect. GYKI 52466 (a specific AMPA receptor antagonist) at 30 microM almost completely suppressed the glutamate-induced inward current in HCs. Cyclothiazide at 100 microM depolarized the HC dark membrane potential by about 5 mV and reduced the amplitudes of the voltage responses to dim lights, but enhanced the voltage responses to bright lights. Cyclothiazide had no effect on either the dark potential or the light responses of rods and cones. Con A at 300 microgram ml-1 had no effect on either the dark potential or the light responses of the HC. GYKI 52466 (30 microM) hyperpolarized the HC dark membrane potential by about 55 mV and almost completely suppressed the light responses. We conclude from these results that the postsynaptic glutamate- and light-induced responses in the tiger salamander retinal horizontal cells are mediated by AMPA-preferring, and not kainate-preferring glutamate receptors. The functional roles of AMPA receptors and their desensitization kinetics in visual information processing are discussed.

Ambystoma↗
PubMed1998

Evaluation of nuclide renal dynamic image in diagnosing diabetic nephropathy.

Twenty non-insulin dependent diabetics were given nuclide renal dynamic image examination to investigate its significance in the diagnosis of diabetic nephropathy (DNP). The results showed that 1) the glomerular filtration was hyperfunctioned in the diabetics with less than 5 years course, whereas it was impaired in the diabetics with over 5 years course and 2) nuclide renal dynamic image could reveal the glomerular hyperfiltration without beta 2-microglobulinuria or microalbuminuria, suggesting that it is superior to the clinical biochemical parameters in the diagnosis, especially in the early identification of DNP.

Diabetes Mellitus, Type 2↗
PubMed1998

Prolonged intercostal nerve blockade in sheep using controlled-release of bupivacaine and dexamethasone from polymer microspheres.

BACKGROUND: Previous work from the authors' group characterized a prolonged percutaneous blockade of the sciatic nerve in rats using bupivacaine-dexamethasone microspheres. The goals of the current study are to examine the (1) efficacy of bupivacaine microspheres with and without dexamethasone for intercostal blockade in sheep; (2) scaling of dose and duration with a 100-fold increase in body size from rats to sheep; (3) local toxicity and adverse systemic reactions to bupivacaine microspheres with and without dexamethasone. METHODS: Intercostal blocks were performed percutaneously in sedated sheep. Sensory blockade was measured at repeated time points by absent flinch response to skin pinch. Plasma bupivacaine concentrations were measured using high performance liquid chromatography. Chest wall specimens were examined by light microscopy. RESULTS: The duration of intercostal blockade increased with bupivacaine dose for animals receiving from 8 to 80 mg/kg of microspheres with and without dexamethasone. At each dose, microspheres containing dexamethasone had a longer duration of block than microspheres without dexamethasone. From 8 to 80 mg/kg, the mean duration of block with bupivacaine-dexamethasone microspheres increased from 4 to 13 days. Plasma concentrations of bupivacaine remained 10-fold below the convulsive EC50 concentration for sheep. Chest wall histology showed a significant granulomatous reaction around bupivacaine microspheres but not around bupivacaine-dexamethasone microspheres. CONCLUSIONS: A single administration of bupivacaine-dexamethasone microspheres produces an effective chest wall analgesia of several days' duration. This may prove useful clinically for thoracic surgery or trauma.

Anesthetics, Local↗