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Biomedical subjects

G Yang

Publications and source records attributed to G Yang.

At least 253 records · Page 14Linked to original sources
PubMed1998

Clinical performance of the AMDL DR-70 immunoassay kit for cancer detection.

A clinical study using DR-70 immunoassay for the detection of 13 different cancers have been conducted with 277 healthy subjects and 136 cancer patients. The test results showed that the DR-70 immunoassay kit was capable of detecting cancers with high degree of specificity and sensitivity. At 95% specificity level, the sensitivity of the assay was 87.8%, 92.6%, 65.2% and 66.7%, respectively for lung, stomach, breast and rectum cancers. Furthermore the test kits were shown to be stable and performed reproducibly.

Adolescent↗
PubMed1998

Cerebral ischemia after bilateral carotid artery occlusion and intraluminal suture occlusion in mice: evaluation of the patency of the posterior communicating artery.

Cerebral ischemia models using mice have drawn increasing attention, particularly because of the availability of transgenic animals. However, the variability of intracranial vasculature at the circle of Willis in mice can influence the degree of ischemia in both the bilateral common carotid artery (CCA) occlusion and intraluminal suture occlusion models. We have developed a method to predict the extent of the anastomosis between carotid and vertebrobasilar circulation in three mouse strains (C57BL/6, CBA, and DBA/2) by measuring cortical microperfusion with laser Doppler flowmetry during a 1-minute occlusion of both CCA. When animals showed residual cortical microperfusion of less than 12% during bilateral CCA occlusion, the mice showed absence of functional anastomosis, developed ATP depletion in the frontal cortex during occlusion, and had ischemic neuronal death in the hippocampus and caudoputamen after occlusion for 15 minutes and recirculation for 7 days. Furthermore, those mice exhibited decreased local cerebral blood flow and associated ischemic neuronal death in the hippocampus, within the territory supplied by the posterior cerebral artery, with the intraluminal suture occlusion model. The current study demonstrates the need for assessment of intracranial vasculature in each animal by measuring cortical microperfusion during temporary occlusion of both CCA, no matter whether cerebral ischemia is produced by bilateral CCA occlusion or intraluminal suture occlusion in transgenic mice.

Animals↗
PubMed1998

A new genetic algorithm technique in optimization of permanent 125I prostate implants.

Real time optimized treatment planning at the time of the implant is desirable for ultrasound-guided transperineal 125I permanent prostate implants. Currently available optimization algorithms are too slow to be used in the operating room. The goal of this work is to develop a robust optimization algorithm, which is suitable for such application. Three different genetic algorithms (sGA, sureGA and securGA) were developed and compared in terms of the number of function evaluations and the corresponding fitness. The optimized dose distribution was achieved by searching the best seed distribution through the minimization of a cost function. The cost function included constraints on the periphery dose of the planned target volume, the dose uniformity within the target volume, and the dose to the critical structure. Adjustment between the peripheral dose, the dose uniformity and critical structure dose can be achieved by varying the weighting factors in the cost function. All plans were evaluated in terms of the dose nonuniformity ratio, the conformation number and the dose volume histograms. Among these three GA algorithms, the securGA provided the best performance. Within 2500 function evaluations, the near optimum results were obtained. For a large target volume (5 cm x 4 cm x 4.5 cm) including urethra with 20 needles, the computer time needed for the optimization was less than 5 min on a HP735 workstation. The results showed that once the best set of parameters was found, they were applicable for all sizes of prostate volume. For a fixed needle geometry, the optimized plan showed much better dose distribution than that of nonoptimized plan. If the critical structure was considered in the optimization, the dose to the critical structure could be minimized. In the cases of irregular and skewed needle geometry, the optimized treatment plans were almost as good as ideal needle geometry. It is concluded that this new genetic algorithm (securGA) allows for an efficient and rapid optimization of dose distribution, which is suitable for real time treatment planning optimization for ultrasound-guided prostate implant.

Algorithms↗
PubMed1998

Cerebellar vascular and synaptic responses in normal mice and in transgenics with Purkinje cell dysfunction.

We used transgenic mice with Purkinje cell dysfunction (PO3 line) to study the role of these neurons in the increase in cerebellar blood flow (BFcrb) produced by stimulation of the cerebellar parallel fibers (PF). Mice (age 8-10 wk) were anesthetized (halothane) and artificially ventilated. Arterial pressure and end-tidal CO2 were monitored continuously. Arterial blood gases were measured. The PF were stimulated electrically (100 microA, 30 Hz; 40 s), and the increases in BFcrb were monitored by a laser-Doppler flow probe. First, we characterized the increases in BFcrb and the field potentials produced by PF stimulation in normal mice. PF stimulation evoked the typical field potentials and increased BFcrb by 60 +/- 4% (100 microA, 30 Hz; n = 10). The increases in BFcrb were attenuated by the broad-spectrum glutamate receptor antagonist kynurenate (-84 +/- 3%; P < 0.05 analysis of variance; n = 5), by the DL-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)quinoxaline (-62 +/- 6%; P < 0.05; n = 5), and by the nitric oxide synthase inhibitor N omega-nitro-L-arginine (-46 +/- 7%; P < 0.05; n = 5). In PO3 transgenic mice, the increases in BFcrb produced by PF stimulation were reduced (P < 0.001) at every stimulus intensity and frequency tested (residual increase at 100 microA, 30 Hz: 19 +/- 2%; n = 6). The field potentials evoked by PF stimulation also were abnormal in that they lacked the late negative wave (n = 6), a finding consistent with lack of depolarization of Purkinje cells. The residual flow response in the transgenics was abolished by N omega-nitro-L-arginine (n = 5; P > 0.05). Ultrastructural studies showed that the density of PF-Purkinje cell synapses is reduced in PO3 mice, whereas the morphology of molecular layer interneurons (stellate cells) is normal. The findings suggest that Purkinje cells are responsible for a sizable component of the flow response whereas molecular layer interneurons mediate the remainder of the response. The study provides evidence that mouse mutants with spontaneous or genetically engineered cerebellar abnormalities could be useful to study the cellular and molecular correlates of functional hyperemia in the central nervous system.

Action Potentials↗
PubMed1998

Developmental expression of human angiotensinogen in transgenic mice.

Transgenic mice containing the human angiotensinogen (HAGT) gene were utilized to determine the developmental regulation of HAGT expression. RNase protection assay on total RNA obtained from whole transgenic fetuses revealed that HAGT expression was first detected at embryonic day 8.5 (E8.5) and was abundant from E9.5 onward. The earliest expression of the HAGT transgene appeared to precede the earliest expression of the endogenous mouse AGT gene by 1-2 days. Northern blot analysis revealed moderate levels of HAGT mRNA in liver and kidney and low levels of HAGT mRNA in heart and brain from E16.5 (day 16.5 of gestation) onward. HAGT mRNA in liver, although abundant during late gestation and in 2-wk-old and adult mice, decreased transiently around birth. In situ hybridization performed on sections from whole fetuses revealed that HAGT mRNA was restricted to the developing liver and heart between E9.5 and E11.5 but became more widespread to include the developing aorta, brain, subcutaneous tissues, and vertebra at E13.5. In situ hybridization analysis on fetal kidneys from late gestation, newborn, and 2-wk-old mice demonstrated a progressive restriction of HAGT mRNA to developing cortical proximal tubular cells. These data illustrate the developmental tissue-specific regulation of HAGT expression and demonstrate that sequences present in the transgene can confer an appropriate developmental expression profile.

Angiotensinogen↗
PubMed1998

Regulatory elements required for human angiotensinogen expression in HepG2 cells are dispensable in transgenic mice.

Previous researchers have identified two sequences present upstream (angiotensinogen gene-activating element [AGE2]) and downstream (d61-2) of the human angiotensinogen gene that act as cell-specific enhancers of transcription in transiently transfected HepG2 cells. To examine the importance of these two sequences in regulating tissue- and cell-specific expression of the gene in vivo, we generated transgenic mice containing the mutations in the context of a genomic transgene previously shown to exhibit appropriate tissue and cell specificity. The ability of these sequences to enhance transcription of a basal human angiotensinogen promoter was confirmed in transient transfection assays in HepG2 cells, and mutations within the AGE2 and d61-2 sequences abolished transactivation of the promoter. Tissue- and cell-specific expression was examined in three lines of transgenic mice carrying the d61-2 mutation, two lines of transgenic mice carrying the AGE2 mutation, and three founder transgenic mice carrying a double-mutant construct. Although the absolute levels of expression varied among lines, the pattern of tissue-specific expression was essentially unaltered by the mutations. In situ hybridization confirmed that the mutations were also dispensable for proximal tubule-specific expression within the kidney. Finally, a comparison of transgene expression with transgene copy number revealed a direct proportionality in liver (R=.77, P=.0014) and kidney (R=.76, P=.0024). These results clearly demonstrate that these sites, which strongly induce promoter activity in cells in culture, are not required for appropriate expression of the gene when present in a genomic construct in vivo.

Angiotensinogen↗
PubMed1998

Amelioration of hippocampal neuronal damage after global ischemia by neuronal overexpression of BCL-2 in transgenic mice.

BACKGROUND AND PURPOSE: Reports suggesting the involvement of apoptosis in ischemic neuronal damage have been accumulating, and protection against apoptotic death by BCL-2 has been shown in many types of cells. Overexpression of BCL-2 has been shown to reduce infarct size after focal ischemia. The purpose of the present study was to assess whether BCL-2 exerted its effect on selective neuronal vulnerability after transient global ischemia. METHODS: Transgenic mice overexpressing BCL-2 in neurons and their littermates were subjected to transient forebrain ischemia for 12 minutes, and the hippocampus was examined 7 days later with conventional histology, immunohistochemistry, and in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling of fragmented DNA. RESULTS: Although both types of mice showed a similar degree of ischemic insult, transgenic mice showed a lesser degree of neuronal death together with DNA fragmentation in the hippocampus than their littermates. CONCLUSIONS: Overexpression of BCL-2 in neurons mitigates selective neuronal vulnerability in the hippocampus of transgenic mice after transient global ischemia.

Animals↗
PubMed1998

Activation of cerebellar climbing fibers increases cerebellar blood flow: role of glutamate receptors, nitric oxide, and cGMP.

BACKGROUND: The mechanisms regulating the cerebellar microcirculation during neural activity are poorly understood. One of the major neural inputs to the cerebellar cortex is the climbing fiber (CF), a pathway that uses excitatory amino acids, including glutamate, as a transmitter. We studied whether CF activation increases cerebellar blood flow (BFcrb) and, if so, we investigated the role of glutamate receptors, nitric oxide (NO) and cGMP, in the response. METHODS: The CF were activated by harmaline administration (40 mg/kg, i.p.) in halothane-anesthetized rats with a cranial window placed over the cerebellar vermis. BFcrb was monitored by a laser-Doppler probe, and arterial pressure and blood gases were controlled. RESULTS: With Ringer superfusion, harmaline produced sustained increases in BFcrb that peaked 20 minutes after administration (+115 +/- 13%; n=6; P<.05). The increases in BFcrb were substantially reduced by superfusion with tetrodotoxin (10 micromol/L; -91 +/- 5%; n=5; P<.05 from Ringer). The response was also attenuated by the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor inhibitor 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo-(F)-quinoxaline (100 micromol/L; -70 +/- 6%; P<.05; n=5), but not by the N-methyl-D-aspartate receptor blocker 2-amino-5-phosphonopentanoic acid (500 micromol/L; P>.05; n=5). The response was attenuated by the nonselective NO synthase (NOS) inhibitor nitro-L-arginine (1 mmol/L; -73 +/- 5%; n=6) or by 7-NI (50 mg, i.p.; -71 +/- 5%; n=5), a relatively selective neuronal NOS inhibitor. The soluble guanylyl cyclase inhibitor 1H-1,2,4oxadiazolo[4,3-a]quinoxalin-1-one (100 micromol/L) attenuated the response to harmaline (-73 +/- 5; P<.05; n=6) but not to superfusion with adenosine (P>.05; n=5) or 8-bromo-cGMP (P>.05; n=5). CONCLUSIONS: Activation of the CF system increases BFcrb. The response depends on activation of glutamate receptors and is in large part mediated by NO via stimulation of soluble guanylyl cyclase. Glutamate receptors NO and cGMP are important factors in the mechanisms of functional hyperemia in cerebellar cortex.

2-Amino-5-phosphonovalerate↗
PubMed1998

Experimental study on intramuscular injection of eukaryotic expression vector pcDNA3- IL-6 on BXSB mice.

OBJECTIVE: To study the role of IL-6 in systemic lupus erythematosis (SLE). METHODS: We constructed eukaryotic expression vector pcDNA3- IL-6 encoding for IL-6 and injected it intramuscularly into BXSB mice. 22 of the 3.5-month-old male BXSB mice were divided into two groups. One group was injected with the pcDNA3-IL-6 100 micrograms per mouse twice at the interval of 20 days. Another group was injected with plasmid pcDNA3 at the same time as control. The ANA and proteinuria were monitored every 10 days, and the IL-6 activity in serum, IgG, C3 deposition and IL-6 expression in kidney detected at the 40th day. RESULTS: IL-6 encoding plasmid had harmful effects on murine SLE with increased ANA level, proteinuria, IgG, C3 deposition and IL-6 expression in kidney, but there was no difference of serum GPT levels between the two groups. CONCLUSION: Excessive production of IL-6 could play an important pathogenic role in SLE. Blocking or reducing IL-6 secretion might be a new therapy for SLE.

Animals↗
PubMed1998

[A study on the coverage, strategy and cost of hepatitis B vaccination in China, 1996].

To understand the coverage, strategy and cost of hepatitis B (HB) vaccination of China in recent years, a randomized two-stage household sampling survey was carried out at 112 Disease Surveillance Points(DSPs) from 25 provinces, autonomous regions and municipalities of China in 1996. Results showed that the rates of HB vaccination coverage among neonates were 96.9% in the urban DSPs and 50.8% in the rural DSPs in 1993-1994, while in 7-9 year-old students both rates were 85.8% and 31.5% in 1994, respectively. Up to 1994, 97.5% of the urban DSPs and 73.9% of the rural DSPs had a neonates vaccination against HB program integrated with routine EPI. Some of the DSPs had a lower neonates coverage due to insufficient amountad unreasonable distribution of the vaccine (used for adults) and high cost. It seems necessary to evaluate the maternal prescreening program regarding the quality of serological testing to HBVMs. Remarkable achievements have been made in terms of strategy development and planning on HB immunization in China.

Child↗
PubMed1998

[Data cleaning in the 1995-1996 national smoking prevalence survey].

The authors introduced the procedure of data cleaning in the 1995-1996 national smoking prevalence survey, and the objectives, principles, procedures, quality evaluation and points for attention of data cleaning were summarized. Data cleaning must be carried out from the smallest investigative unit. The logical relationship among variables must be fully considered for the revision of incorrect values. In dealing with miss values, their roles in the statistical analyses must be evaluated. Comparing the differences in some important variables before and after cleaning is a useful method for assessing whether the representativeness of the data has been changed during the cleaning process.

China↗
PubMed1998

[Prognostic significance of P53 protein expression in patients with colorectal adenocarcinoma].

In order to investigate the prognostic significance of P53 protein expression in the patients with colorectal adenocarcinoma, we used the P53 monoclonal antibody and ABC immunohistochemical method combined with the repairing method for antigen by microwave oven to study the relationship between the overexpression of P53 protein and the prognosis in 40 cases of colorectal adenocarcinoma. The results showed that 65% (26/40) cases of colorectal adenocarcinoma were positive for overexpression of P53 protein. The 5-year survival rate for positive cases was 50%, but 87.5% for negative cases. These findings suggest that the overexpression of P53 protein closely associates with the prognosis in colorectal adenocarcinoma (P < 0.05), thus it might become a new prognostic indicator. The prognosis in colorectal adenocarcinoma could be predicted thoroughly by considering the expression of P53 protein in combination with the traditional prognostic factors.

Adenocarcinoma↗
PubMed1998

[Alteration of fatty acid components of erythrocyte membrane and insulin resistance in diabetic patients].

OBJECTIVE: To study the effect of alteration of erythrocyte membrane fatty acid components and fluidity on insulin resistance (ISR) in NIDDM patients. METHODS: The fatty acid(FA) components and fluidity of erythrocyte membrane in 52 NIDDM patients with and without hyper-insulinemia were examined by a high-performance liquid chromatographic method and flourescence polarization technique. RESULTS: The content and composition erythrocyte membrane arachidonate (AA) were significantly lower in NIDDM patients than in controls, and also markedly lower in patients with hyperinsulinemia than those without hyperinsulinemia. The diabetics had increased erythrocyte membrane microviscosities as compared with controls, and membrane microviscosities were higher in diabetics with hyperinsulinemia than those without hyperinsulinemia. AA contents of erythrocyte membrane were negatively correlated with membrane membrane microviscosities and positively with ISI in NIDDM patients. CONCLUSION: In NIDDM patients, hyperinsulinemia and ISI bring about AA metabolic abnormalities and decreased AA contents in cell membrane. Alteration of cell membrane FA components results in the changes of membrane fluidity, and the latter can increase IRS.

Aged↗
PubMed1998

[A study of p16 gene and its protein expression in rhabdomyosarcoma].

OBJECTIVE: To evaluate the relationship between alteration of p16 gene, its protein expression and the pathogenesis and development of rhabdomyosarcoma (RMS). METHODS: 44 cases of RMS were examined for alteration of p16 gene with PCR-SSCP and 47 cases of RMS were examined for p16 protein expression with immunohistochemical method. RESULTS: The homozygous deletion of p16 gene was observed in 2 cases and mutations in 6 cases. Of these 8 cases with altered p16 gene, 6 had extensive invasion, recurrence or metastasis. The total negative rate of p16 protein expression in RMS was 38.3% (18/47 cases). Of these 8 cases with alterations of p16 gene, negative expression for p16 protein was observed in 7 cases and positive in only 1 cases. In contrast, no structural abnormalities of the p16 gene were detected in another 11 cases with negative expression of p16 protein. Higher rates of p16 gene abnormality and loss of p16 protein were observed in ARMS than in ERMS. Higher rate of extensive invasion, recurrence or metastasis was also found in the group negative for p16 protein. CONCLUSION: The abnormalities of p16 gene and loss of p16 protein expression may be related to the pathogenesis and development of some RMS.

Cyclin-Dependent Kinase Inhibitor p16↗
PubMed1998

[The preparation of chiral column of cellulose triacetate coated on small pore silica gel and the separation of enantiomers].

The cellulose triacetate (CTA) prepared by heterogeneous acetylation and coated on small pore 3-aminopropyl silica gel (10 nm) was used as chiral stationary phase for HPLC (OA column). The racemes of three drugs, two fulvenes and one dazine, were separated on this column. Among these racemes, timolol maleas was separated using 1.0 mol/L NaClO4:95% ethanol = 10:90 as mobile phase. Without NaClO4 in mobile phase, the resolution of timolol maleas can not occur. Ethanols of 95%-98% were used as mobile phase for other racemes. The influence of the content of water in mobile phase on the chiral separation of praziquentelum, the retention time and separation factor (alpha) were reduced with the increase of water content in mobile phase. When the content of water in the mobile phase was 13%, praziquentelum could not be separated. It was found that in the case of samples No. 1 and No. 2, when the substituents R1 and R2 or R'1 and R'2 of fulvenes are 4-methoxybenzoyl and 4-methoxyphenyl, the chiral separations of fulvenes can be obtained. For sample No. 4 when R1 and R2 of fulvenes are 2-methylbenzoyl and 2-methylphenyl or in the case of No. 5, when R1 and R2 are 5-bromo-2-furoyl and 5-bromo-2-furan, the chiral separations of fulvenes can not be achieved. For sample No. 6 and No. 7, when R'1 are 4-chlorobenzoyl and benzoyl or R'2 are 4-chlorophenyl and phenyl, the chiral separation also can not be achieved. The column performance and separation factor were not obviously reduced after used for four months.

Cellulose↗
PubMed1998

[Effect of -6 degrees bed-rest on T-lymphocyte proliferation and cytokines production in human].

In this study, the effect of -6 degrees head-down bed-rest on proliferation of T lymphocyte stimulated by phytohemagglutinin, a kind of polyclone T cell activators and cytokines production were observed. The results showed: after 2 d bed-rest, proliferation of T lymphocyte stimulated by phytohemagglutinin decreased significantly; the activity of interleukin-2 trended to decrease; the expression of interleukin-2 receptor tended to increase; the production of interleukin-6 decreased significantly. After 6 d bed-rest, T lymphocyte proliferation restored to normal; the activity of interleukin-2 and expression of interleukin-2 receptor had no change; the production of interleukin-6 decreased significantly. This result demonstrated that -6 degrees bed-rest can decrease T lymphocyte proliferation function, and this decrease may be caused by the reduction of cytokines secretion.

Adult↗