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Biomedical subjects

J Luo

Publications and source records attributed to J Luo.

At least 73 records · Page 4Linked to original sources

PGE(2) is essential for gap junction-mediated intercellular communication between osteocyte-like MLO-Y4 cells in response to mechanical strain.

We have observed, in our previous studies, that fluid flow increases gap junction-mediated intercellular coupling and the expression of a gap junction protein, connexin 43, in osteocyte-like MLO-Y4 cells. Interestingly, this stimulation is further enhanced during the poststress period, indicating that a released factor(s) is likely to be involved. Here, we report that the conditioned medium obtained from the fluid flow-treated MLO-Y4 cells increased the number of functional gap junctions and connexin 43 protein. These changes are similar to those observed in MLO-Y4 cells directly exposed to fluid flow. Fluid flow was found to induce PGE(2) release and increase cyclooxygenase 2 expression. Treatment of the cells with PGE(2) had the same effect as fluid flow, suggesting that PGE(2) could be responsible for these autocrine effects. When PGE(2) was depleted from the fluid flow-conditioned medium, the stimulatory effect on gap junctions was partially, but significantly, decreased. Addition of the cyclooxygenase inhibitor, indomethacin, partially blocked the stimulatory effects of mechanical strain on gap junctions. Taken together, these studies suggest that the stimulatory effect of fluid flow on gap junctions is mediated, in part, by the release of PGE(2). Hence, PGE(2) is an essential mediator between mechanical strain and gap junctions in osteocyte-like cells.

Animals↗

Expression of functional gap junctions and regulation by fluid flow in osteocyte-like MLO-Y4 cells.

Osteocytes are thought to be mechanosensory cells that respond to mechanical stress by sending signals to other bone cells to initiate bone remodeling. An osteocyte-like cell line MLO-Y4 provides a model system to examine whether gap junctions participate in the regulation of osteocyte function and signaling by mechanical stress. In this study, we show that MLO-Y4 cells are coupled and that gap junction channels mediate this coupling. Biochemical analyses show that connexin 43 (Cx43) is a major gap junction protein expressed in MLO-Y4 cells and approximately 5% of Cx43 protein is phosphorylated. MLO-Y4 cells were exposed to mechanical stress using a parallel plate flow chamber to model bone fluid flow shear stress. Fluid flow increased significantly the length of the dendritic processes, a morphological characteristic of osteocytes. A redistribution of the gap junction protein, Cx43 also was observed from a location circling the nucleus to punctate spots in the cytoplasm and in the dendritic processes. "Scrape-loading" dye transfer analyses showed that fluid flow increased intercellular coupling and increased the number of cells coupled immediately after fluid flow treatment, in direct proportion to shear stress magnitude. Although intercellular coupling continued to increase, stimulation of Cx43 protein expression during the poststress period was found to be biphasic. Cx43 protein was elevated 30 minutes after application of stress but decreased at 24 h poststress. Pulsating fluid flow had a similar stimulatory effect as steady fluid flow on gap junctions. However, this stimulatory effect in osteocyte-like cells was not observed in osteoblast-like 2T3 cells. Together, these results show that fluid flow has stimulatory effects on osteocyte-like MLO-Y4 cells with early effects on cellular morphology, opening of gap junctions, and redistribution of Cx43 protein and delayed effects on Cx43 protein expression. The high expression of Cx43 and its location in the cytoplasm also suggest that Cx43 may have unknown functions in addition to forming gap junctions. These studies indicate that gap junctions may serve as channels for signals generated by osteocytes in response to mechanical loading.

Blotting, Western↗

Identification of Sarcocystis hominis-like (Protozoa: Sarcocystidae) cyst in water buffalo (Bubalus bubalis) based on 18S rRNA gene sequences.

DNA templates were extracted from isolates of Sarcocystis hominis-like cysts collected from cattle and water buffalo, as well as from Sarcocystis fusiformis cysts and Sarcocystis suihominis cysts. The 18S rRNA genes were amplified using DNA from a single cyst as the templates. Approximately 1,367-1,440 bp sequences were obtained. The sequence difference in isolates of Sarcocystis hominis-like cysts from water buffaloes, and isolates of S. hominis cysts from cattle were very low, only about 0.1%, much lower than the lowest value (1.7%) among different species. Combined with their morphological structure, these sequence data indicate that the 4 isolates from cattle and water buffalo might be the same species, i.e., S. hominis, suggesting that both cattle and water buffalo may serve as the intermediate hosts for this parasite. Apparently, this is the first report using a single cyst to do such work and is a useful way to distinguish the Sarcocystis cyst in an intermediate host that may be simultaneously infected by several different Sarcocystis species.

Animals↗

Community Health Centers and racial/ethnic disparities in healthy life.

This study examined disparities in health status among individuals of different racial and ethnic groups cared for by the nation's community health centers (CHCs) and compared these results with the findings for individuals using non-CHC sites as their usual source of care. The sample consisted of CHC users from the 1994 CHC User Survey and non-CHC users from the 1994 National Health Interview Survey. Bivariate comparisons were made between individuals' race/ethnicity and their experience of healthy life, an integrated measure that incorporates both activity limitation and self-perceived health status. Multiple regressions were followed to examine the independent association of race/ethnicity with healthy life experience for both CHC and non-CHC users while controlling for sociodemographic correlates of health. Among CHC users, racial and ethnic minorities did not have worse health than whites, but among non-CHC users there were significant racial and ethnic disparities: whites experienced significantly healthier life than both blacks and non-white Hispanics. These findings persisted after controlling for sociodemographic correlates of health. The results indicate that while racial/ethnic disparities in health persist nationally, these disparities do not exist within CHCs, safety-net providers with an explicit mission to serve vulnerable populations.

Adolescent↗

Growth and slaughter traits of Boer x Spanish, Boer x Angora, and Spanish goats consuming a concentrate-based diet.

The number of Boer crossbred meat goats has been increasing rapidly, although how their growth and slaughter traits compare with those of Spanish goats and influences of maternal genotype have not been thoroughly evaluated. This information would be useful to achieve optimal meat goat production systems and yield of goat products desired by consumers. Therefore, postweaning growth (9 to 24 wk of age) and slaughter traits (212 +/- 5.0 d of age) of Boer x Spanish, Spanish, and Boer x Angora wethers (n = 16, 18, and 18 for growth measures, respectively, and n = 6 per genotype for slaughter traits) consuming a concentrate-based diet were compared. Over the 16-wk performance period, ADG, DMI, and ADG:DMI were greater (P < 0.05) for Boer crossbreds than for Spanish goats (ADG: 154, 117, and 161 g; DMI: 646, 522, and 683 g/d; ADG:DMI: 263, 235, and 261 g/kg for Boer x Spanish, Spanish, and Boer x Angora, respectively). Dressing percentage (46.3, 47.3, and 47.0% of BW; SE = 1.21) and quality grade score (11.17, 9.67, and 11.17 for Boer x Spanish, Spanish, and Boer x Angora, respectively; SE = 0.66 [12 = Choice+; 11 = Choice; 10 = Choice-; 9 = Good+]) were similar among genotypes. Weights of some noncarcass components were greater for Boer crossbreds than for Spanish goats, but relative to empty BW, noncarcass component weights were similar among genotypes. Concentrations of moisture, ash, fat, and protein in carcass and noncarcass components did not differ among genotypes. Contributions to the carcass of different primal cuts were similar among genotypes, and there were few differences in concentrations of separated lean, bone, and fat in primal cuts. In conclusion, when consuming a concentrate-based diet, early postweaning growth rate was similar between Boer x Spanish and Boer x Angora wethers and greater for Boer crossbreds than for Spanish wethers. Slaughter traits were primarily related to differences in final BW.

Animals↗

Up-regulation of transcription of smooth muscle myosin alkali light chain by ethanol in human breast cancer cells.

Both epidemiological and experimental studies indicate that ethanol is a tumor promoter and that chronic ethanol exposure enhances metastasis of breast cancer cells, and with an in vitro model (T47D human breast cancer cells), we have previously demonstrated that ethanol exposure stimulated the migration of breast cancer cells. In the present study, differential display reverse transcription polymerase chain reaction was used to identify ethanol-responsive genes in T47D cells. Three differentially displayed, ethanol-responsive gene fragments were identified, and their expression was confirmed by Northern blot hybridization. Sequence analysis revealed that one cDNA fragment represented the myosin alkali light chain (MLC 1sm) of human smooth muscle. The expression of MLC 1sm was found to be significantly higher in breast cancer cells than in normal mammary epithelial cells. With T47D cells, ethanol induced an additional duration- and concentration-dependent up-regulation of MLC 1sm. At 400 mg/dl, an ethanol-mediated increase was evident at 6 h (55% increase), peaked at 24 h (2.7-fold increase) following exposure, and diminished thereafter. At pharmacologically relevant concentrations (e.g., 100 mg/dl), ethanol produced a significant increase of MLC 1sm expression, and progressively higher ethanol concentrations resulted in more up-regulation. The half-life of MLC 1sm mRNA was not altered, however, the transcription rate of MLC 1sm was significantly increased by ethanol. MLC is a structural component of the cytoskeleton of eukaryotic cells, and it plays critical roles in the regulation of cell shaping, movement, and growth. Thus, ethanol-mediated up-regulation of MLC may be an underlying molecular mechanism for its tumor promoting effect.

Blotting, Northern↗

Heparan sulfate and chondroitin sulfate proteoglycans inhibit E-selectin binding to endothelial cells.

E-selectin is a cell adhesion molecule involved in the initial rolling and adhesion of leukocytes to the endothelium during inflammation. In addition, in vitro studies have suggested that an interaction between E-selectin and binding sites such as sialyl Lewis X-containing oligosaccharides on endothelial cells may be important for angiogenesis. In order to investigate the binding of E-selectin to endothelial cells, we developed an ELISA assay using chimeric E-selectin-Ig molecules and endothelial cells fixed on poly-L-lysine coated plates. Our results indicate that E-selectin-Ig binds to both bovine capillary endothelial cells and human dermal microvascular endothelial cells in a calcium-dependent and saturable manner. The binding is inhibited markedly by heparin and by syndecan-1 ectodomain, and moderately by chondroitin sulfate, but not by sialyl Lewis X-containing oligosaccharides. These results suggest that heparan sulfate and chondroitin sulfate proteoglycans on endothelial cells are potential ligands for E-selectin.

Animals↗

[Effect of dissolved oxygen on the suspension culture of Taxus chinensis].

The effect of dissolved oxygen controlled level on the taxol production by suspended cell culture of Taxus chinensis was examined in shake flasks and in a 20L aerated and agitated bioreactor with a six-flat-bladed turbine. It was found in shake flasks that oxygen supply exhibited significant influence on the production of taxol. Further investigation in bioreactor showed that noly 1.5 mg/L taxol was produced when DO(dissolved oxygen) level was 20%. Taxol production increased when DO level was increased to 40%-60%. Moreover, taxol accumulation was remarkably improved by the cultivation of cells initially at the DO level of 60% during the growth phase for 14 days followed by changing the DO level to 20%-40% during the taxol production phase for another 10 days. An optimum taxol level of 7.2 mg/L was obtained by the dissolved oxygen controlled process.

Cell Culture Techniques↗

[Studies of the origin of Chinese domestic fowls].

A total of 539 bases fragment of mitochondrial DNA D-loop region of six domestic chicken breeds (30 individuals) were sequenced and compared to that of red junglefowl, grey junglefowl, green junglefowl and Lafayette's junglefowl issued in GenBank, and the phylogenetic trees for the chickens constructed based on the D-loop sequences. The results indicated that the four species of genus Gallus had great differences between each other, the G. g. domesticus was the next of kin to red junglefowl in Thailand and its adjacent regions, and near of kin to red junglefowl in Indonesian, Lafayette's junglefowl, grey junglefowl and green junglefowl one by one in proper order, suggesting that the red junglefowl in Thailand and its neighbour areas sufficed as the matriarchic ancestor of Chinese domestic fowls. It was also discovered that the two subspecies of Thailand i.e. G. g. gallus and G. g. spadiceus should belong to one subspecies because of their far lower differentiation compared to that among the domestic breeds.

Animals↗

[Studies of genetic diversity of Zhejiang native chicken breeds].

A total of 539 bases of mitochondrial DNA D-loop region of five native chicken breeds of Zhejiang province and the white leghorn chicken (as the control) were sequenced by DNA sequencing technique, and the phylogenetic trees of the chicken breeds were constructed. The results showed that 24 variation sites i.e. 4.45% sequence divergence were detected among the 30 DNA sequences, and the six breeds belonged to two different maternal lineage, one included Xianju chicken and White Leghorn chicken which had the same maternal origin, the other included Lingkun chicken, Baiyiner chicken, Wugu chicken and Xiaoshan chicken which had the same matriarchic ancestor. Among the latter lineage, Lingkun chicken, Baiyiner chicken and Wugu chicken had a closer relationship to each other than to Xiaoshan chicken.

Animals↗

[Effects of five different polar extracts from Herba pogostemonis being gotten rid of volatile oil on gastrointestinal tract].

The effects of the five extracts from Herba pogostmonis being gotten rid of volatile oil on gastrointestinal tract were studied. The results showed that the five extracts could increase gastric secretion of acid and activity of pepsin, reduce the incidence of diarrhea induced by Folium sennae and relieve the gripping pain induced by abdominal administration of acetic acid. The extract of ethyl acetate could also inhibit the normal and neostigmine induced mice intestinal propellant movement. The effect of extract of ethyl acetate was consistent with clinical application. The above results indicated that the clinical effect of Herba pogostmonis may be comprehensive action of above five different polar extracts.

Animals↗

A pilot-scale study on biofilters for controlling animal rendering process odours.

Heating of animal tissue during the process of rendering liberates a variety of odorous compounds. The performance of biofiltration in removing these odours was investigated using pilot-scale biofilters containing different media (sand, finely and coarsely crushed wood bark, and bark/soil mixture). Odour-removal performance of the biofilters was determined using olfactometry. Biofilter odour removal efficiencies of between 29.7% and 99.9% were measured at influent odour concentrations of between 143,100 and 890,000 odour units m(-3), and various air loading rates (0.074-0.592 m(-3) air m(-3) medium min(-1)). Biofilters with bark or bark/soil media and low air loading rates gave the best odour removal. The bark and sand biofilters generally maintained good odour reduction for about three years at an air loading rate of 0.148 m(-3) air m(-3) medium min(-1). Drainage from the biofilters contained significant concentrations of nitrogenous and organic compounds, suggesting that controlled leaching has the potential to remove accumulated substances in biofilter media from rendering gas emissions and increase the longevity of a biofilter system. High pressure drop across biofilter media can adversely affect the odour removal performance. Sand and fine bark, due to their small particle size, caused high pressure drops. Coarse bark showed negligible pressure drop at several examined air loading rates. Pressure drop also increased with moisture content, particularly in sand and fine bark biofilters. Overall pressure drop characteristics of the biofilters described in this paper were maintained without significant change over the three year operation.

Abattoirs↗

[Evaluation on peer education program among injecting drug users].

OBJECTIVE: To reduce risk behaviors which promotes human immuno deficiency virus (HIV) transmission among drug users. METHODS: A peer education program was implemented among drug users in drug detoxification centers in Kunming from May 1998 to June 2000. Before and after intervention, through random sampling, subjects were recruited to assess the impact of the program. Focus group discussion and a small sample of follow-up in communities were used for evaluation. RESULTS: Three hundred and six and 418 subjects were interviewed before and after the intervention program. Rates regarding "sharing needles" had a reduction from 68.3% to 62.0% (chi 2 = 2.61, P < 0.01, while "never cleaning a needle" increased from 3.3% to 15.8% (chi 2 = 19.41, P < 0.01), and "used needles disposal to garbage bin" increased from 58.4% to 81.8% (chi 2 = 40.23, P < 0.01). Thirty-four drug users were followed in their communities and 67.6% were no longer sharing needles but none reported using a condom when having casual sex. CONCLUSION: Peer education program among drug users in detoxification centers had limited impact. In order to control the epidemic of AIDS in drug using population, more effective strategies need to be explored.

Evaluation Studies as Topic↗

[The effect of lactate-buffered peritoneal dialysis fluid in human peritoneal mesothelial cells function].

OBJECTIVE: To investigate the effect of lactate-buffered peritoneal dialysis fluid (L-PDF) on human peritoneal mesothelial cells (HPMC) function. METHODS: Mesothelial cells from human omentum were isolated and cultured in vitro. Proliferation of HPMC was detected by MTT assay. The quantity of interleukin-8 (IL-8) and fibronectin (FN) in culture supernatants was determined by ELISA. Reverse transcription and polymerase chain reaction amplification were used to detect the expression of IL-8 mRNA in HPMC. Total cellular protein in these supernatants was estimated by using Lowry method. RESULTS: L-PDF inhibited proliferation of HPMC in a time-dependent manner. The levels of IL-8 and FN in the supernatants were remarkably high, and expression of IL-8 mRNA was up-regulated in HPMC exposure to L-PDF. During a subsequent recovery period of 48 hours in culture medium containing lipopolysaccharide (LPS, 10 mg/L), enterotoxin of staphylococcus aureus (10 mg/L) or TNFalpha(10 x 10(6) U/L), the levels of FN in the supernatants increased (P < 0.05). The levels of IL-8 also increased in HPMC stimulated with TNFalpha(P < 0.01). CONCLUSION: L-PDF inhibited proliferation of HPMC and increased levels of IL-8 and FN in the HPMC.

Dialysis Solutions↗

[Analysis of environmental gradient and community of forest-swamp ecotone in Changbai mountains].

This paper discussed the change pattern between environmental gradients and community structure, productivity and plant diversity of forest-swamp ecotones, and the mechanism forming those community's traits, which could supply a theoretical basis for conserving and managing the biological resources of ecotonal communities. By setting up sample belts along the environmental gradients on three kinds of ecotones between forests and swamps in Changbai Mountains and through investigating initial data and establishing regression models, the authors studied the dynamic pattern of species composition, diameter class and age class of dominant species, plant diversity, community productivity of forest-swamp ecotone communities with environmental gradients. The results showed that the distribution patterns of community structure characteristics, plant diversity and community productivity were consistent with the changes of environmental gradients of forest-swamp ecotones. Along the environmental gradient from swamp to forest, the displace of dominant species happened, and the species number increased by positive exponent. The diameter distribution of trees decreased by inverse curve, and the age class of trees was suited to cubic distribution. The plant diversity increased by quadratic, and the community biomass increased by cubic power curve along the environmental gradients. The above-mentioned results suggested that the relationships between communities and environmental gradients were closely related.

China↗

[Study of bacteriology on local application of Tinidazole stilus in treatment for periodontitis].

OBJECTIVE: The study was designed to evaluate the antiseptic efficacy of Tinidazole stilus against periodontal pathogen. METHODS: A total of 41 patients with periodontitis were included in this study. 26 of them were treated by Tindazole stilus and other 15 cases were treated by metronidazole stilus as controls. The prevalence of subgingival bacteria from both group were examined. RESULTS: The eliminate rates for Black pigmented anaerobic rod (Porphyromonas gingivalis, Prevotella intermedius, Prevotella melaninogenicus), Fusobacteriums, Prevotella oris, Prevotella oralis, Eubacterium and Actinomyces were 95.8% 94.1%, 83.3% and 76.5%. The anti-bacterial efficiency of Tinidazole against periodontal pathogen was significantly higher than that of metronidazole (P < 0.05). CONCLUSION: It appears to be effective to use Tinidazole stilus as local application against periodontal pathogens.

Administration, Topical↗