Biomedical subjects

K Yang

Publications and source records attributed to K Yang.

At least 55 records · Page 3Linked to original sources

PubMed2001

Origins of spontaneous and noxious stimuli-evoked miniature EPSCs in substantia gelatinosa.

The origins of spontaneous and noxious stimuli-evoked glutamatergic miniature excitatory postsynaptic currents (mEPSCs) in substantia gelatinosa (SG) neurons were investigated by using whole-cell voltage-clamp technique on adult rat spinal cord slice. The properties of mEPSCs of SG neurons from rats either neonatally capsaicin-treated or sciatic nerve ligated showed no difference from those of intact SG neurons, indicating independence of spontaneous mEPSCs on primary afferent fibers. In the presence of tetrodotoxin (TTX), capsaicin, which noxiously stimulated fine primary afferent fibers, caused increase of the mEPSCs frequency, but did not affect the amplitude profiles or mean amplitudes. TTX affected neither the spontaneous mEPSCs nor capsaicin-induced mEPSCs frequency increase. The results suggest that spontaneous mEPSCs in SG are mediated by presynaptic spontaneous glutamate release predominantly originating from interneuron terminals rather than from primary afferent terminals; under noxious stimulation, however, mEPSCs frequency increase is mediated by primary afferent excitation.

Afferent Pathways↗

PubMed2001

Helper-dependent adenoviral vector-mediated gene transfer in aged rat brain.

Transfer of the neurotrophin gene into brain can attenuate age-related deficits such as neuronal atrophy and memory loss, but a suitable vector for this procedure has been lacking. The toxicity and immunogenicity of first-generation adenoviral vectors with E1 deletion (fgAdv) prohibit the application of gene transfer in the majority of central nervous system disorders. Here, we report less toxic and persistent gene expression mediated by helper-dependent adenovirus (hdAdv) in aged rat brain. After intrahippocampal or intraventricular inoculation of the vector, transgene expression was monitored by X-Gal staining and compared with fgAdv-mediated expression. Host inflammatory and immune responses against these vectors were evaluated by immunohistochemical detection of microglia, astrocytes, and infiltrating macrophages, as well as by enzyme-linked immunosorbent assay of cytokines TNF-alpha and IL-1beta. Transgene expression mediated by hdAdv persisted for more than 183 days regardless of inoculation site, as compared with 33 and 66 days for fgAdv-mediated expression after intraventricular and intrahippocampal inoculation, respectively. Inoculation with hdAdv was also associated with reduced numbers of activated microglial cells, astrocytes, and infiltrating macrophages in brain tissue. Secretion of the proinflammatory cytokines TNF-alpha and IL-1beta was minimal after hdAdv but not after fgAdv inoculation. These findings indicate that hdAdv would provide a safe and effective means to transfer therapeutic genes into aged brain.

Adenoviridae↗

PubMed2001

Targeted inactivation of the p21(WAF1/cip1) gene enhances Apc-initiated tumor formation and the tumor-promoting activity of a Western-style high-risk diet by altering cell maturation in the intestinal mucosal.

Elimination of both alleles of the gene that encodes the cyclin kinase inhibitor p21(WAF1/cip1) increases the frequency and size of intestinal tumors in Apc1638+/- mice that inherit a mutant allele of the Apc gene, and intermediate effects are seen if a single p21 allele is inactivated. The increased tumor formation is associated with altered cell maturation in the intestinal mucosa of the p21-deficient mice--increased cell proliferation, and decreased apoptosis, and goblet cell differentiation--that is also a function of p21 gene dosage. Moreover, a Western-style diet that mimics principal risk factors for colon cancer (high fat and phosphate, low calcium and vitamin D) accelerates tumor formation in Apc1638+/- mice, and the loss of a single or both p21 alleles is additive with the tumor-promoting effects of this diet, resulting in more and larger tumors, and a highly significant decrease in survival time. Thus, p21 normally suppresses Apc-initiated tumor formation and is haplo-insufficient in this regard. This is consistent with recent reports that Apc initiates tumor formation by up-regulating c-myc expression through altered beta-catenin-Tcf signaling and that c-myc then up-regulates cdk4, whose activity is inhibited by p21. Decreased expression of p21 is also a marker of poor prognosis in patients, and the data presented suggest that dietary alterations in patients undergoing treatment for colon cancer might be highly effective in improving outcome.

Adenomatous Polyposis Coli Protein↗

PubMed2001

Treatment of recalcitrant-pigmented flat warts using frequency-doubled Q-switched Nd-YAG laser.

BACKGROUND AND OBJECTIVE: Recalcitrant-pigmented flat warts may persist for years despite treatment. Many methods have been used to manage pigmented flat warts, but their efficiencies are varied. Since pigmented flat warts are very similar to lentigo clinically, we used frequency-doubled Q-switched (FDQS) Nd-YAG laser at the wavelength of 532 nm to treat recalcitrant-pigmented flat warts and evaluated the effect. STUDY DESIGN/MATERIALS AND METHODS: Seven patients with recalcitrant-pigmented flat warts were enrolled in this study. We set the FDQS Nd-YAG laser to deliver 2.5 J/cm(2) fluence at the wavelength of 532 nm to treat these lesions. After 6 months, we evaluated the recurrence of pigmented flat warts, pigmentary, and textural changes on the treated areas. RESULTS: There were absences of recurrent lesions, pigmentary, and textural changes on the treated areas of these seven patients after 6 months. CONCLUSIONS: Through both selective photothermolysis effect and propagation of photoacoustic waves, FDQS Nd-YAG laser at the wavelength of 532 nm can be used as an effective alternative to treat recalcitrant pigmented flat warts.

Adolescent↗

PubMed2001

A role for secondary V(D)J recombination in oncogenic chromosomal translocations?

Chromosomal translocations are hallmarks of certain lymphoproliferative disorders. Indeed, in many leukemias and lymphomas, translocations are the transforming event that brings about malignancy. Recurrence of the immunoglobulin (Ig) and T-cell receptor (Tcr) loci at the breakpoints of oncogenic chromosomal translocations has led to speculation that the lymphocyte-specific process of V(D)J rearrangement, which is necessary for the generation of functional Ig and TCR antigen receptors on B and T lymphocytes, mediates translocation. Recent studies have led to a fuller understanding of the molecular mechanisms of V(D)J rearrangement and have revealed that the V(D)J recombinase possesses latent transposase activity. These studies have led to plausible models of illegitimate V(D)J recombination producing chromosomal translocations consistent with those present in lymphomas and leukemias. Errors of V(D)J recombination may even generate lymphomas with the phenotypes of mature cells. For example, follicular and Burkitt's lymphomas have been classified by phenotype and somatic genotype as malignant germinal center (GC) B or post-GC B cells. The GC is a site of affinity maturation where B cells undergo V(D)J hypermutation and Ig class switch; in addition, much evidence has accumulated to suggest that GC B cells may also support secondary V(D)J recombination. Interestingly, all three of these elements, genomic plasticity, mutation, and translocation breakpoints near switch sites or recombinational elements, are characteristic of certain lymphomas. The high frequency of lymphomas carrying these GC markers suggests that the GC reaction may play a significant role in lymphomagenesis.

Amino Acid Motifs↗

PubMed2001

Voltage-clamp recordings of postsynaptic currents in substantia gelatinosa neurons in vitro and its applications to assess synaptic transmission.

We describe here procedures for recording postsynaptic currents in substantia gelatinosa neurons on a transverse spinal cord slice preparation with an attached dorsal root. At the holding potential of -70 mV, glutamatergic spontaneous excitatory postsynaptic currents (EPSCs) and dorsal root (A delta and/or C fiber) stimulation-evoked EPSCs could be observed. Whereas at the holding potential of 0 mV, spontaneous inhibitory postsynaptic currents (IPSCs) and dorsal root A delta fiber stimulation-evoked IPSCs could be encountered. The methods make it possible to evaluate synaptic transmission by analysing the postsynaptic currents on dorsal root attached spinal cord slice.

Animals↗

PubMed2001

Total knee arthroplasty in diabetic patients: a study of 109 consecutive cases.

The outcome of 109 consecutive total knee arthroplasties in 86 diabetic patients was studied. There were 73 women and 13 men, with a mean age of 69 years (range, 56-84 years). All the patients were followed for at least 36 months. The mean follow-up period was 42 months (range, 36-60 months). In the early postoperative period (< or =1 month), the overall wound infection rate was 7.3% (8 knees). The risk of deep joint infection was 5.5% (6 knees). Of the patients, 15% (17 knees) developed a urinary tract infection after the operation. The superficial and deep infection rates were higher when compared with a similar study in the general population. Maximum precautions should be taken for diabetic patients undergoing total knee arthroplasties.

Aged↗

PubMed2001

Comparison of calcium supplementation or low-fat dairy foods on epithelial cell proliferation and differentiation.

Epidemiological evidence suggests that dietary calcium and vitamin D intake are inversely related to incidence of colon cancer. Previous studies have demonstrated that supplementation of the diet with calcium in the form of calcium tablets or low-fat dairy foods alters colonic epithelial cell proliferation from a higher- to a lower-risk pattern. The present study compared relative effects of administration of calcium carbonate at approximately 900 mg/day (calcium) with those of a low-fat dairy food diet providing about the same amount of calcium (dairy) in a cross-over "head-to-head" study of 40 subjects at risk for colonic neoplasia. Dietary intake of macronutrients was similar in the two study periods, except for a slight increase in protein intake during dairy calcium supplementation. Rectal epithelial cell proliferation was studied in flat endoscopically normal-appearing mucosa at baseline and at the end of each of the two study periods and showed a significant reduction in epithelial crypt cell labeling index from 12.5% to 9.1% (calcium) or 9.3% (dairy) as well as in proliferating cells in the upper 40% of the crypt from 0.09 to 0.03 in the calcium- and low-fat dairy-supplemented intervention groups. No significant changes in two epithelial cell differentiation markers, cytokeratin AE1 and acidic mucins, were found. Furthermore, there were no differences in epithelial cell apoptosis or expression of the proapoptotic gene product BAK. These data indicate that increased dietary calcium given as supplements or in the diet in low-fat dairy foods lowers epithelial cell proliferation indexes from a higher- to a lower-risk pattern. Because supplemental calcium has been shown to reduce the recurrence of colonic adenomatous polyps in patients at increased risk for colonic neoplasia, our data suggest that supplemental low-fat dairy foods may also be effective.

Adenomatous Polyposis Coli↗

PubMed2001

A Western-style diet induces benign and malignant neoplasms in the colon of normal C57Bl/6 mice.

Decreased dietary intakes of calcium, vitamin D and folic acid have been suggested as risk factors for human colon cancer. We previously fed a Western-style diet (WD) containing reduced calcium, vitamin D and increased fat content to normal C57/Bl6 mice: hyperproliferation, hyperplasia and whole crypt dysplasias developed in the colon following WD administration. Utilizing the same diet, we now also decreased the levels of several nutrients that are required for biochemical reactions involving methyl group inadequacy, i.e. folic acid, methionine, choline and vitamin B(12). Dietary levels of these nutrients were reduced to nutrient-density levels approximating those consumed by large segments of human Western populations. This further modification of the WD resulted in adenoma and carcinoma development in normal mouse colon (P < 0.04 compared with AIN-76A diet). The results indicate, for the first time, that a semi-purified rodent diet designed to mimic the human Western diet can induce colonic tumors in normal mice without carcinogen exposure.

Adenoma↗

PubMed2001

Expression of lipopolysaccharide binding protein and its receptor CD14 in experimental alcoholic liver disease.

AIM: To evaluate the relationship between the expression of lipopolysaccharides (LPS) binding protein (LBP) and CD14 mRNA and the severity of liver injury in alcohol-fed rats. METHODS: Twenty Wistar rats were divided into two groups:ethanol-fed group (group E) and control group (group C). Group E was fed with ethanol(5-12 g x kg(-1) x d(-1)) and group C received dextrose instead of ethanol. Rats of the two groups were sacrificed at 4 weeks and 8 weeks. Levels of endotoxin and alanine transaminase (ALT) in blood were measured, and liver pathology was observed under light and electronic microscopy. Expressions of LBP and CD14 mRNA in liver tissues were determined by RT-PCR analysis. RESULTS: Plasma endotoxin levels were increased more significantly in group E(129+/-21) ng x L(-1) and (187+/-35) ng x L(-1) at 4 and 8 wk than in control rats(48+/-9) ng x L(-1) and (53+/-11) ng x L(-1), respectively (P<0.05). Mean values of plasma ALT levels were (1867+/-250) nkat x L(-1) and (2450+/-367) nkat x L(-1) in Group E. The values were increased more dramatically in ethanol-fed rats than in Group C after 4 and 8 weeks. In liver section from ethanol-fed rats, there were marked pathological changes (steatosis, cell infiltration and necrosis). In ethanol-fed rats, ethanol administration led to a significant increase in LBP and CD14 mRNA levels compared with the control group (P<0.05). CONCLUSION: Ethanol administration led to a significant increase in endotoxin levels in serum and LBP and CD14 mRNA expressions in liver tissues. The increase of LBP and CD14 mRNA expression might wake the liver more sensitive to endotoxin and liver injury.

Acute-Phase Proteins↗

PubMed2001

Differential interactions between GSTM1 and NAT2 genotypes on aromatic DNA adduct level and HPRT mutant frequency in lung cancer patients and population controls.

We have studied the influence of GSTM1 and NAT2 genotypes on aromatic DNA adduct level (AL) and HPRT mutant frequency (MF) in smokers with newly diagnosed lung cancer and matched population controls. AL was analyzed in relation to genotypes in 170 cases and 144 controls (113 current/recent smokers and 201 former/never smokers), and MF in 157 cases and 152 controls (155 ever smokers and 154 never smokers). Both genotypes exhibited the a priori expected effects on AL and MF among controls only, especially among smoking controls [significantly lower pack-years (a pack-year is defined as 1 pack of cigarettes/day for 1 year) than among cases]. Among the 42 currently smoking controls, the NAT2 slow genotype [odds ratio (OR), 7.5; 95% confidence interval (CI), 1.5-38.4], in particular in combination with the GSTM1 null genotype (OR, 19.3, 95% CI, 1.1-338.6 for null/slow versus positive/rapid) was strongly associated with high AL. The null/slow combination was also significantly associated with high MF among ever smokers (cases and controls pooled) with lower pack-years (OR, 3.7; 95% CI, 1.3-10.7 versus all of the other genotypes; OR, 5.1; 95% CI, 1.2-22.4 versus positive/rapid). In contrast, an antagonistic gene-gene interaction was seen among smoking cases for both AL and MF. Only currently smoking cases with the combined GSTM1 null and NAT2 rapid genotype showed a positive correlation between InAL and InMF (r, 0.64; P = 0.1), and an increase of AL with both age and daily cigarette use. This genotype combination was also associated with high MF among ever-smoking cases (OR, 4.0; 95% CI, 0.9-17.7 versus positive/rapid). There was a significant interaction between NAT2 genotype and pack-years of smoking among cases, so that the rapid genotype was associated with high MF among ever-smoking cases diagnosed at higher pack-years, whereas the slow genotype was associated with high MF at lower pack-years. These findings suggest that the influence of NAT2 genotype on AL and MF and its interaction with GSTM1 genotype may be dose dependent. The NAT2 slow genotype, in particular when combined with the GSTM1 null genotype, may confer increased susceptibility to adduct formation, gene mutation, and lung cancer when the smoking dose is low.

Adult↗

PubMed2001

Prokaryotic calmodulins: recent developments and evolutionary implications.

Ca2+ is a common intracellular second-messenger molecule in eukaryotic cells and regulates a myriad of cellular processes. Many effects of Ca2+ are mediated by calcium-binding regulatory proteins of the calmodulin superfamily. We propose the idea that calcium-binding proteins originated in high G+C Gram-positive bacteria and were later acquired by eukaryotes.

Amino Acid Sequence↗

PubMed2001

[Cumulative impact assessment: problems and practice in China mainland and Hong Kong].

Including past, present and future impacts in environmental impact assessment (EIA) of the proposed action, it is the important property of cumulative impact assessment (CIA) that different from traditional EIA. It is also the main trend of EIA improvement. From the area of regulation demands, documentation practice, spatial and temporal boundary, key contents and mitigation measures, this paper analyses the status of CIA both of China Mainland and Hongkong in the practice of EIA. The author suggested that technical guidelines for cumulative effects assessment should be set up in China Mainland and Hongkong, CIA should be included in project, region and strategy environment assessment and cumulative impacts should be list clearly in EIA study executive summary and reported in a separate part of the environmental consequences section. Spatial and temporal boundaries and any cumulative impacts addressed within the CIA process should be provided evidence or analysis to support the conclusion. In order to prevent cumulative effects effectively, the focus on CIA should be put on biodiversity, social and economic impacts and global environmental effects.

China↗

PubMed2001

Biomarkers of polycyclic aromatic hydrocarbon-DNA damage and cigarette smoke exposures in paired maternal and newborn blood samples as a measure of differential susceptibility.

Human and experimental evidence indicates that the developing fetus may be more susceptible than the adult to the effects of certain carcinogens, including some polycyclic aromatic hydrocarbons (PAHs). Factors that can modulate susceptibility include proliferation rates, detoxification capabilities, and DNA repair capacity. Biomarkers can facilitate quantification of age-related susceptibility among human populations. In this study, we report on three biomarkers measured in paired blood samples collected at birth from 160 Polish mothers and newborns: 70 pairs from Krakow (a city with high air pollution including PAHs) and 90 pairs from Limanowa (an area with lower ambient pollution but greater indoor coal use). Biomarkers were: WBC aromatic-DNA adducts by (32)P-postlabeling and PAH-DNA adducts by ELISA (as indicators of DNA damage from PAHs and other aromatics) and plasma cotinine (as an internal dosimeter of cigarette smoke). Correlations were assessed by Spearman's rank test, and differences in biomarker levels were assessed by the Wilcoxon signed-ranks test. A significant correlation between paired newborn/maternal samples was seen for aromatic-DNA adduct levels (r = 0.3; P < 0.001) and plasma cotinine (r = 0.8; P < 0.001) but not PAH-DNA adduct levels (r = 0.14; P = 0.13). Among the total cohort, levels of the three biomarkers were higher in newborn samples compared with paired maternal samples. The difference was significant for aromatic-DNA adduct levels (16.6 +/- 12.5 versus 14.21 +/- 15.4/10(8) nucleotides; P = 0.002) and plasma cotinine (14.2 +/- 35.5 versus 8.3 +/- 24.5 ng/ml; P < 0.001) but not for PAH-DNA adduct levels (7.9 +/- 9.9 versus 5.9 +/- 8.2/10(8) nucleotides; P = 0.13). When analyses were restricted to the 80 mother/newborn pairs from whom the blood sample was drawn concurrently (within 1 h of each other), levels of all of the three biomarkers were significantly higher in the newborn compared with paired maternal blood samples (P < 0.05). Results suggest reduced detoxification capabilities and increased susceptibility of the fetus to DNA damage, especially in light of experimental evidence that transplacental exposures to PAHs are 10-fold lower than paired maternal exposures. The results have implications for risk assessment, which currently does not adequately account for sensitive subsets of the population.

Adult↗

PubMed2001

Hyodeoxycholic acid efficiently suppresses atherosclerosis formation and plasma cholesterol levels in mice.

We examined the effect of hyodeoxycholic acid (HDCA) on plasma cholesterol levels and atherosclerosis in mice. In wild-type C57BL/6 mice, feeding increasing amounts of HDCA resulted in i) progressive decrease in dietary cholesterol absorption, ii) increased concentrations of HDCA in the gallbladder bile, iii) decreased liver cholesterol content, iv) increased liver cholesterol synthesis, and v) increased plasma concentrations of HDCA. In C57BL/6 LDL-receptor knockouts (LDLR-KO) the addition of HDCA to chow and a 0.5% cholesterol diet decreased their total plasma cholesterol levels by 21% and 62%, respectively, because of a decrease in VLDL and LDL cholesterol. Turnover studies showed that HDCA has no effect on VLDL removal from plasma. Furthermore, the addition of HDCA to chow- and 0.5% cholesterol-fed LDLR-KO mice decreased the aortic root atherosclerosis lesion area by 50% and 80%, respectively. Finally, we tested the effect of HDCA on intestinal tumor formation. Feeding C57BL/6 ApcMin mice with HDCA did not affect the number of tumors but decreased the tumor volume in these animals. These results suggest that HDCA might have beneficial effects in the treatment of increased plasma cholesterol levels and atherosclerosis.

Absorption↗

PubMed2001

[Transgenic loach produced by using sperm cells mediated by high molecules].

The pCH110 plasmid DNA which has a marker gene LacZ controlled by a SV40 promoter was mixed with a kind of high molecule of dendrimers(cyclic core dendrimer) and then formed a DNA/dendrimer complex. Loach sperms were incubated with the DNA/dendrimer complex. Then in situ hybridization was used to detect whether the sperm cells captured the foreign DNA or not. Results show that the number of sperm capturing foreign DNA via dendrimers as vectors was obviously increased. The sperms were mixed with eggs for in vitro fertilization. PCR was used to detect the transgenic loach fries. Obvious expression of LacZ gene in the head of transgenic loach were observed by analysis through LacZ histochemical staining of embryos or fries.

Animals↗

PubMed2001

[Expression of adhesion molecules on CD34(+) hematopoietic precursor cells from normal human bone marrow, cord blood and mobilized blood].

OBJECTIVE: To investigate the expression of adhesion molecules on CD(34)(+) hematopoietic precursor cells from normal human bone marrow, cord blood and mobilized peripheral blood, and the mechanism of peripheral blood precursor cells mobilization. METHODS: CD(34)(+) hematopoietic cells were separated from bone marrow, cord blood and mobilized peripheral blood by CD(34) MultiSort Kit immunomagnetic bead system. The purity was examined by FACSort. The CD(34)(+) cells and post-short-term cultured CD(34)(+) cells were labeled in an indirect immuno-fluorescence procedure with adhesion molecules CD(11a), CD(18), CD(44), CD(49d), CD(54), CD(58) and CD(62L) monoclonal antibodies and assayed by FACSort. RESULTS: The expression of CD(11a), CD(18), CD(49d), CD(54), CD(58) and CD(62L) of mobilized peripheral blood CD(34)(+) cells was lower than that of bone marrow ones, especially for CD(49d) and CD(62L). Similar to mobilized peripheral blood CD(34)(+) cells, cord blood CD(34)(+) cells also showed a lower expression of CD(11a), CD(18), CD(44), CD(49d), CD(62L) than that of bone marrow ones, especially for CD(62L), but expression of CD(54) was higher than that of bone marrow and mobilized peripheral blood CD(34)(+) cells. CONCLUSION: The expressions of cell adhesion molecules on CD(34)(+) cells in normal bone marrow, cord blood and mobilized peripheral blood were quite different, the mechanism of peripheral blood precursors mobilization might be related to downregulation of cell adhesion molecule expression.

Antigens, CD34↗

PubMed2001

[Expression of cell cycle associated proteins cyclin D1 and P16 in endometrial carcinoma and the correlation between their expression status].

OBJECTIVE: To study the expression of cell cycle associated proteins Cyclin D1, P16 in endometrial carcinoma and their correlation to clinical parameters, and to assess the correlation between their expression status. METHODS: Immunohistochemical method was used to detect Cyclin D1 and P16 expressions in 64 cases of endometrial carcinoma. RESULT: The positive rate of Cyclin D1 was 54.68%. The Cyclin D1 expression was significantly associated with FIGO stage (P < 0.05). The positive rate of P16 was 53.13% and its expression was related to age, histological grade and FIGO stage (P < 0.05). There was an inverse correlation between Cyclin D1 and P16, r = -0.4007 (P < 0.01). CONCLUSION: Cyclin D1 and P16 had cooperative effect and may play an important role in the development and progression of endometrial carcinoma.

Adenocarcinoma↗