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Biomedical subjects

X Yu

Publications and source records attributed to X Yu.

At least 235 records · Page 13Linked to original sources
PubMed1998

Differential expression of the arabidopsis nia1 and nia2 genes. cytokinin-induced nitrate reductase activity is correlated with increased nia1 transcription and mrna levels

Nitrate reductase (NR) activity increased up to 14-fold in response to treatment of Arabidopsis thaliana seedlings with the cytokinin benzyladenine. NR induction was observed in seedlings germinated directly on cytokinin-containing medium, seedlings transferred to cytokinin medium, and seedlings grown in soil in which cytokinin was applied directly to the leaves. About the same level of induction was seen in both wild-type and Nia2-deletion mutants, indicating that increased NR activity is related to the expression of the minor NR gene, Nia1. The steady-state Nia1 mRNA level was increased severalfold in both wild-type and mutant seedlings after benzyladenine treatment. Transcript levels of the Nia2 gene, which is responsible for 90% of the NR activity in developing wild-type seedlings, did not show any changes upon cytokinin treatment. Nuclear run-on assays demonstrated that Nia1 gene transcription increased dramatically after cytokinin treatment.

Journal Article↗
PubMed1998

Dehydrogenase regulation of metabolite oxidation and efflux from mitochondria in intact hearts.

To test how alpha-ketoglutarate dehydrogenase (alpha-KGDH) activity influences the balance between oxidative flux and transmitochondrial metabolite exchange, we monitored these rates in isolated mitochondria and in perfused rabbit hearts at an altered kinetics (Km) of alpha-KGDH for alpha-ketoglutarate (alpha-KG). In isolated mitochondria, relative Km dropped from 0.23 mM at pH = 7.2 to 0.10 mM at pH 6.8 (P < 0.05), and alpha-KG efflux decreased from 126 to 95 nmol.min-1.mg-1. In intact hearts, Km was reduced with low intracellular pH, while matching control workload and respiratory rate with increased Ca2+ (pHi = 7.20, perfusate CaCl2 = 1.5 mM; pHi = 6.89, perfusate CaCl2 = 3 +/- 1 mM). Sequential 13C nuclear magnetic resonance spectra from hearts oxidizing [2-13C]acetate provided tricarboxylic acid cycle flux and the exchange rate between alpha-KG and cytosolic glutamate (F1). Tricarboxylic acid cycle flux was 10 mumol.min-1.g-1 in both groups, but F1 fell from a control of 9.3 +/- 0.6 to 2.8 +/- 0.4 mumol.min-1.g-1 at low Km. The results indicate that increased activity of alpha-KGDH occurs at the expense of alpha-KG efflux during support of normal workloads.

Acetates↗
PubMed1998

The influence of physical structure and charge on neurite extension in a 3D hydrogel scaffold.

Understanding neural cell differentiation and neurite extension in three-dimensional scaffolds is critical for neural tissue engineering. This study explores the structure-function relationship between a 3D hydrogel scaffold and neural cell process extension and examines the role of ambient charge on neurite extension in 3D scaffolds. A range of agarose hydrogel concentrations was used to generate varied gel physical structures and the corresponding neurite extension was examined. Agarose gel concentration and the corresponding pore radius are important physical properties that influence neural cell function. The average pore radii of the gels were determined while the gel was in the hydrated state and in two different dehydrated states. As the gel concentration was increased, the average pore radius decreased exponentially. Similarly, the length of neurites extended by E9 chick DRGs cultured in agarose gels depends on gel concentration. The polycationic polysaccharide chitosan and the polyanionic polysaccharide alginate were used to incorporate charge into the 3D hydrogel scaffold, and neural cell response to charge was studied. Chitosan and alginate were covalently bound to the agarose hydrogel backbone using the bi-functional coupling agent 1,1'-carbonyldiimidazole. DRGs cultured in chitosan-coupled agarose gel exhibited a significant increase in neurite length compared to the unmodified agarose control. Conversely, the alginate-coupled agarose gels significantly inhibited neurite extension. This study demonstrates a strong, correlation between the ability of sensory ganglia to extend neurites in 3D gels and the hydrogel pore radius. In addition, our results demonstrate that charged biopolymers influence neurite extension in a polarity dependent manner.

Alginates↗
PubMed1998

[Studies on mutagenicity of humic acid samples collected from arsenosis-affected areas in China].

OBJECTIVE: To explore whether there is mutagenicity of humic acid samples collected from arsenosis affected areas in China. METHODS: Ames' test was used for natural humic acid samples extracted from the coal containing high arsenic in Guizhou Province, and the well water in the areas with blackfoot disease in Taiwan and with arsenosis in Inner Mongolia of China. RESULTS: Coefficients of revertant mutation were 1.02-0.82 net revertant per microgram (rev/microgram) of humic acid extracted from the coal containing high arsenic in Guizhou without rat liver homogenate (-S9), and 1.53-1.12 rev/microgram of that with rat liver homogenate (+S9), with an obvious dose-response relationship. CONCLUSION: Humic acid extracted from the coal containing high arsenic produced in Guizhou could cause stronger direct mutation in Salmonella typhimurium TA98 (frameshift mutation) and that extracted from the well water in the areas with blackfoot disease in Taiwan could cause weaker direct mutation in Salmonella typhimurium (-S9), but that extracted from the well water with arsenosis in Inner Mongolia could not cause mutation. Mutagenicity of commercial humic acid, purchased from Aldrich Co. in the United States, arsenic and iron was also studied, and no mutagenicity was found for them independently, but arsenic combined with humic acid, at certain concentrations, could cause weak mutation in TA98 (-S9), with or without iron. No mutagenicity in TA100 (+/- S9, base pair substitution mutation) was found in all the samples mentioned above.

Animals↗
PubMed1998

[Observations of changes in neurobehavioral functions in workers exposed to high-frequency radiation].

OBJECTIVE: To study the effects of exposure to high-frequency radiation on neurobehavioral function of the exposed workers and its measurement in evaluating occupational hazards caused by it. METHODS: Four neurobehavioral functions were tested for the workers exposed to high-frequency radiation with Neurobehavioral Core Tests Battery recommended by WHO. RESULTS: Scores for various indicators in exposed workers were significantly lower than those in controls, and correlated to the detection of neurasthenia in the exposed workers, to certain extent. CONCLUSION: Changes in neurobehavioral function in workers exposed to high-frequency radiation can reflect its important adverse effects.

Adult↗
PubMed1998

CT-guided stereotactic biopsy of deep brain lesions: report of 310 cases.

OBJECTIVE: To evaluate the accuracy of CT-guided stereotactic biopsy in making correct pathological diagnosis and choosing corresponding management of brain tumors. METHODS: From 1991 to 1995, CT-guided stereotactic biopsy was performed in 310 patients with intracerebral lesions which were deep-seated or located in certain main functional areas. The patients were 198 men and 112 women. Their ages ranged from 4.5 to 70 years (average: 39.3 years). The lesions were located in the deep cerebrum (74 patients), the sellar area (62), the basal ganglion (51), the posterior part of the third ventricle (38), other intraventricleular area (21), the cerebellum (17) and the brain stem (9), and intracranial multiple lesions were found in 38 patients. RESULTS: Brain tumors were diagnosed pathologically in 266 patients (85.8%); inflammatory process in 25 (8.1%), other lesions in 8 (2.6%) and uncertain cases were 11 (3.6%). The overall positive rate of biopsy was 96.4% and the positive rate for brain tumor was 85.8%. Intracranial hematomas after biopsy were found in 5 patients (1.6%). There were no deaths induced by the biopsy or other serious complications. CONCLUSIONS: The results suggest that CT-guided stereotactic biopsy is a reliable method for histopathological diagnosis of brain tumors and it is also of great help in selecting appropriate management.

Adolescent↗
PubMed1998

[Cellular sociological characteristics of osteoblasts].

There is a great hope to treat long bone defects with bioactive artificial bone constructed by osteoblasts and biomaterials, in which the key point is to provide an optimum environment for the normal function of osteoblasts. The cellular sociological characteristics of osteoblasts were summarized and it was suggested that the ideal bioactive artificial bone should be composed of inorganic and organic materials together with cellular components such as osteoblasts and vascular endothelial cells, and combined with control release of growth factors, following its implantation it could be vascularized very soon and merged with the host bone by bony consolidation.

Bone Substitutes↗
PubMed1998

A clinical trial of tang shen ning for treatment of diabetic nephropathy.

This paper reports the clinical trial of Tang Shen Ning ([symbol: see text], TSN) for treating diabetic nephropathy (incipient and clinical, as divided by Mogensen). The results showed that the total effective rate in treatment group (TSN + western medicine) was 90.0%, and that in the control group (simply with western medicine), 56.7%. TSN plays important roles in decreasing proteinuria and improving renal functions.

Adult↗
PubMed1998

[Distribution of erythrocyte EsD and PGM1 (phosphoglucomutase) phenotypes in the Han population of Changsha district].

Phenotyping of erythrocyte EsD and PGM1 enzymes was performed by a mixed agarose-starch gel electrophoresis in 165 healthy blood donors of Changsha District. The gene frequencies and cumulative discrepancy power(CDP) were calculated. The phenotype frequencies of EsD and PGM1 were compared not only with the different Chinese nationalities but also with those reported by the other countries showing a good correlation with the phenotype distributions of Han people in the other cities of China. The result showed that the gene frequencies of erythrocyte EsD1 and PGM1(1) were 0.6242 and 0.7121 in Han population of Changsha District, respectively. This method is now used routinely in our laboratory and is superior for the examination of individuality and identification of paternity.

Asian People↗
PubMed1998

[Pathologic changes of palatopharyngeal soft tissue in obstructive sleep apnea syndrome].

OBJECTIVE: To study the pathologic changes of palatopharyngeal soft tissues in patients with OSAS. METHODS: Different analyses have been done on uvular muscles (UM) and/or palatopharyngeal muscles (PPM) in patients with OSAS(n = 27), SS(n = 17) and controls (n = 15). The transverse sections were sequentially stained for HE, myofibrillar ATPase, NADH-TR, Lillie Oil Red-O. Ten specimens were evaluated by transmission electron microscopy(TEM). RESULTS: Patients with OSAS have a significantly smaller percentage of muscle in the uvula than that of SS patients (15.0 +/- 3.0 vs 20.3 +/- 5.5), The percentage of muscle is inversely related to the percentage of fibrous tissue in OSAS group (r = -0.75, Y = 42.6 - 0.64X); The total number and area of muscle fibers, the number and area of type I muscle fibers are significantly lower in OSAS than those in SS (800 +/- 345 vs 1200 +/- 360n; 1.10 +/- 0.56 vs 1.70 +/- 0.60 micron 2; 156 +/- 95 vs 360 +/- 225 n; 920 +/- 350 vs 1365 +/- 540 micron 2 respectively); PPM: The percentage of type I muscle fibers within total muscles and its area are significantly lower in OSAS than those in SS and normal controls(20.5 +/- 4.0 vs 34.5 +/- 4.5 n; 20.5 +/- 4.0 vs 35.5 +/- 4.7; 860 +/- 360 vs 1260 +/- 340 micron 2; 860 +/- 360 vs 1350 +/- 370 micron 2; respectively); the muscles from OSAS patients seemed to show neurogenic alterations. Structurally altered fibers shows myofibrillar loss, increased number of vesicles, and rough Z line and so on. CONCLUSION: Our finding suggest that the neurogenic functional disturbance of pharyngeal dilator muscles may play an important role in causing the airway collapse in OSAS.

Adult↗
PubMed1998

[A program of HLA system for parentage testing and its application].

A software of the HLA blood group system for parentage testing was developed with FoxPro 2.5 system. Chinese prompts helped to follow the process during program running. It is easy to use. 63 cases of parentage testing in our department were calculated, and the results were identical with those of manual calculation. It was believed that this program is useful in the parentage testing.

Blood Group Antigens↗
PubMed1998

[DNA vaccine of Plasmodium falciparum: immune response of BALB/c mice induced by injection of the recombinant plasmid DNA].

AIM: To observe the level of immune responses of BALB/c mice induced by direct injection of the recombinant plasmid DNA and to provide evidence for the application of DNA vaccine of Plasmodium falciparum (P. f.) in animals and humans. METHODS: The recombinant plasmid pcDNA3-Pf8 encoding the hybrid antigens of PfCMR-MSP1(19) was constructed. The presence of Pf8 plasmid was detected in the muscle, liver, kidney, heart, spleen and lung by PCR. ELISA, T lymphocyte transformation test, inhibitory assay of the growth and development of P. f. in vitro were used to determine the level of humoral and Th-cell responses. RESULTS: pcDNA3-Pf8 was amplified by PCR technique in the different tissues from BALB/c mice which were injected with pcDNA3-Pf8. The immune serum was specifically recognized by the soluble antigens of P. falciparum (titer: 1:2,560 by ELISA). The specific proliferative response of spleen T cells from immunized mice was remarkably higher than that of control group, the transformation rate being up to 32.82 +/- 3.64%. The immune serum could also inhibit the growth and development of the erythrocytic stages of P. falciparum in vitro. CONCLUSION: Direct injection with the recombinant plasmid pcDNA3-Pf8 specifically elicits BALB/c mice to generate humoral and cell-mediated immune responses, the resulting immune serum being inhibitory to the growth and development of P. f. in vitro.

Animals↗
PubMed1998

[Cloning and sequencing of the gene coding the sexual stage antigen Pfs48/45 of Plasmodium falciparum].

AIM: To express the antigen Pfs48/45 in vitro and provide an antigen for the development of the transmission-blocking vaccine. METHODS: According to the published nucleotide sequence of Pfs48/45 of Plasmodium falciparum isolate NF54, a pair of oligonucleotides was designed and used as primers(P1, P2). The gene encoding the gametocyte/gamete-specific membrane protein Pfs48/45 of P. falciparum isolate FCC1/HN has been amplified by using polymerase chain reaction (PCR) technique. The PCR product was purified and directly sequenced by the dideoxynucleotide terminator method with 5'-end primer P1. At the same time, the purified PCR product was digested with BamHI and EcoRI and cloned into the plasmid pcDNA3, then the recombinant clones were transformed into E. coli strain TG1. The recombinant plasmid pcDNA3-Pfs48/45 was screened and identified by PCR amplification and restriction analysis. RESULTS: 1. The gene fragment Pfs48/45 was specifically amplified from the genomic DNA of Plasmodium falciparum isolate FCC1/HN; 2. The sequence demonstrated that the that the 5'-end nucleotide and predicted aminoacid sequence of Pfs48/45 from FCC1/HN isolate was basically identical with that from NF54 isolate. We found that the sequence of the Pfs48/45 gene from the isolate FCC1/HN differs from the published sequence(isolate NF54) only at positions 307 and 372(T-->C). The substitution of T-->C at the position of 372 generates a new restriction site Taq I. The PCR product digested by Taq I generates DNA fragment of 984 bp and 379 bp, suggesting that the PCR product is the gene encoding the transmission blocking antigen Pfs48/45; 3. The gene fragment of Pfs48/45 was directly inserted into the BamHI and EcoRI site of plasmid pcDNA3. CONCLUSION: The nucleotide sequence of Pfs48/45 of Plasmodium falciparum isolate FCC1/HN from south China was similar to that of isolate NF54. The recombinant plasmid pcDNA3-Pfs48/45 was successfully constructed, providing a means to evaluate the role and biological function of this sexual-stage-specific protein of Pfs48/45.

Amino Acid Sequence↗
PubMed1998

[Cloning and expression of Schistosoma japonicum eggshell protein gene].

AIM: To construct an eukaryotic expression system pcDNA3/ESG-HeLa cell and explore the possibility of whether the eggshell protein might be used as potential targets for vaccine development. METHODS: The eggshell protein gene (ESG) was amplified using PCR technique and inserted into vector pcDNA3 to construct recombinant vector pcDNA3/ESG. The expression of the eggshell protein was performed in HeLa cell line. SDS-PAGE, dot-ELISA and Western blotting were used to identify the antigenicity of the expressed product. RESULTS: The amplification of ESG (618) bp was achieved and high level expression of the eggshell protein was obtained in HeLa cells and the amount of total expressed products was up to 24.4%. Dot-ELISA and Western blot analysis demonstrated that the expressed protein could be recognized by sera from rabbits infected with S. japonicum and from female worm- or egg-immunized rabbits. In addition, the expressed protein could specifically stimulate proliferative response of the immunized BALB/c mouse spleen cells, the transformation rate being up to 44.57%. CONCLUSION: The eukaryotic expression system pcDNA3/ESG was successfully established and high level expression of the eggshell protein of S. japonicum was achieved in HeLa cell line. The expressed recombinant protein exhibited immunological activities.

Animals↗