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Biomedical subjects

P Yu

Publications and source records attributed to P Yu.

At least 19 recordsLinked to original sources
PubMed2006

A 3D analysis of oxygen transfer in a low-cost micro-bioreactor for animal cell suspension culture.

A 3D numerical model was developed to study the flow field and oxygen transport in a micro-bioreactor with a rotating magnetic bar on the bottom to mix the culture medium. The Reynolds number (Re) was kept in the range of 100-716 to ensure laminar environment for animal cell culture. The volumetric oxygen transfer coefficient (k(L)a) was determined from the oxygen concentration distribution. It was found that the effect of the cell consumption on k(L)a could be negligible. A correlation was proposed to predict the liquid-phase oxygen transfer coefficient (k(Lm)) as a function of Re. The overall oxygen transfer coefficient (k(L)) was obtained by the two-resistance model. Another correlation, within an error of 15%, was proposed to estimate the minimum oxygen concentration to avoid cell hypoxia. By combination of the correlations, the maximum cell density, which the present micro-bioreactor could support, was predicted to be in the order of 10(12) cells m(-3). The results are comparable with typical values reported for animal cell growth in mechanically stirred bioreactors.

Animals↗
PubMed2006

D1 dopamine receptor hyperphosphorylation in renal proximal tubules in hypertension.

A defect in the coupling of the D(1) receptor (D(1)R) to its G protein/effector complex in renal proximal tubules plays a role in the pathogenesis of spontaneous hypertension. As there is no mutation of the D(1)R gene in the spontaneously hypertensive rat (SHR), we tested the hypothesis that the coupling defect is associated with constitutive desensitization/phosphorylation of the D(1)R. The following experiments were performed: (1) Cell culture and membrane preparations from rat kidneys and immortalized rat renal proximal tubule cells (RPTCs); (2) immunoprecipitation and immunoblotting; (3) cyclic adenosine 3',5' monophosphate and adenylyl cyclase assays; (4) immunofluorescence and confocal microscopy; (5) biotinylation of cell surface proteins; and (6) in vitro enzyme dephosphorylation. Basal serine-phosphorylated D(1)Rs in renal proximal tubules, brush border membranes, and membranes from immortalized RPTCs were greater in SHRs (21.0+/-1.5 density units, DU) than in normotensive rats (7.4+/-2.9 DU). The increased basal serine phosphorylation of D(1)Rs in SHRs was accompanied by decreased expression of D(1)R at the cell surface, and decreased ability of a D(1)-like receptor agonist (fenoldopam) to stimulate cyclic adenosine 3',5' monophosphate (cAMP) production. Increasing protein phosphatase 2A activity with protamine enhanced the ability of fenoldopam to stimulate cAMP accumulation (17+/-4%) and alter D(1)R cell surface expression in intact cells from SHRs. Alkaline phosphatase treatment of RPTC membranes decreased D(1)R phosphorylation and enhanced fenoldopam stimulation of adenylyl cyclase activity (26+/-6%) in SHRs. Uncoupling of the D(1)R from its G protein/effector complex in renal proximal tubules in SHRs is caused, in part, by increased D(1)R serine phosphorylation.

Alkaline Phosphatase↗
PubMed2006

Mechanism of neuroprotective effect induced by QingKaiLing as an adjuvant drug in rabbits with E. coli bacterial meningitis.

OBJECTIVE: To explore the neuroprotective effects and underlying mechanism of QingKaiLing (QKL) as an adjuvant treatment for bacterial meningitis. METHOD: E. coli bacterial meningitis rabbits were treated with antibiotics (ampicillin) alone or in combination with QKL. The number of leukocytes and the concentration of protein in the cerebrospinal fluid (CSF) of rabbits were determined at 0, 16, and 26 hours after treatment. Brain water, sodium, potassium, and calcium contents were determined at the 26-hour time point. The level of matrix metalloproteinase-9 in the brain was also determined by Western blot. RESULT: The average number of leukocytes and the concentration of protein in CSF of the QKL adjuvant treatment group were reduced compared with the ampicillin alone group. Brain water, sodium, and calcium contents were reduced in the QKL adjuvant treatment group. The level of MMP-9 in brain tissue was also reduced in the QKL adjuvant treatment group. CONCLUSION: QKL adjuvant treatment alleviates the aggravated inflammatory reaction and partially protects brain tissue from antibiotic-induced injury. The mechanism of this neuroprotective effect of QKL may be due to decreased levels of Ca2+ and MMP-9 in the brain.

Acute Disease↗
PubMed2006

Percutaneous intravascular stents for treatment of portal venous stenosis after liver transplantation: midterm results.

Portal vein stenosis after liver transplantation is a relatively uncommon vascular complication that may result in graft loss if not promptly treated. The purpose of this study was to evaluate the midterm result of the use of intravascular stents for portal vein stenosis after liver transplantation. From April 2004 to September 2005, percutaneous transhepatic balloon dilation with stent deployment was performed in nine cases. Varices were embolized with stainless steel coils in two cases. No procedure-related complication occurred. Portal venous patency was maintained in all nine patients from 6 to 19 months (mean 10 months). In conclusion, an intravascular stent is an effective treatment for the portal vein stenosis after liver transplantation with excellent midterm patency.

Angioplasty, Balloon, Coronary↗
PubMed2006

Illness-related factors, stress and coping strategies in relation to psychological distress in HIV-infected persons in Hong Kong.

This study examined the relationships among illness-related factors, stress, coping strategies and psychological distress in HIV-infected persons in Hong Kong (N=118). Multiple regression analyses were used to examine the models of psychological distress as a function of demographic factors, illness-related factors, psychosocial stressors and coping. Results showed that positive thinking was inversely related to psychological distress and avoidance was associated with higher level of anxiety. However, the use of problem solving was found to be inversely related to anxiety. Results are discussed in the context of Chinese culture and the service in Hong Kong.

Adaptation, Psychological↗
PubMed2006

MICA-STR, HLA-B haplotypic diversity and linkage disequilibrium in the Hunan Han population of southern China.

Major histocompatibility complex (MHC) class I chain-related gene A (MICA) is located 46 kb centromeric to HLA-B and encodes a stress-inducible protein. MICA allelic variation is thought to be associated with disease susceptibility and immune response to transplants. This study was aimed to investigate the haplotypic diversity and linkage disequilibrium between human leukocyte antigen (HLA)-B and (GCT)(n) short tandem repeat in exon 5 of MICA gene (MICA-STR) in a southern Chinese Han population. Fifty-eight randomly selected nuclear families with 183 members including 85 unrelated parental samples were collected in Hunan province, southern China. HLA-B generic typing was performed by polymerase chain reaction-sequence-specific priming (PCR-SSP), and samples showing novel HLA-B-MICA-STR linkage were further typed for HLA-B allelic variation by high-resolution PCR-SSP. MICA-STR allelic variation and MICA gene deletion (MICA*Del) were detected by fluorescent PCR-size sequencing and PCR-SSP. Haplotype was determined through family segregation analysis. Statistical analysis was applied to the data of the 85 unrelated parental samples. Nineteen HLA-B specificities and seven MICA-STR allelic variants were observed in 85 unrelated parental samples, the most predominant of which were HLA-B*46, -B60, -B*13, and -B*15, and MICA*A5, MICA*A5.1 and MICA*A4, respectively. Genotype distributions of HLA-B, MICA-STR loci were consistent with Hardy-Weinberg proportions. The HLA-B-MICA-STR haplotypic phases of all 85 unrelated parental samples were unambiguously assigned, which contained 30 kinds of HLA-B, MICA-STR haplotypic combinations, nine of them have not been reported in the literature. Significant positive linkage disequilibria between certain HLA-B and MICA-STR alleles, including HLA-B*13 and MICA*A4, HLA-B*38 and MICA*A9, HLA-B*58 and MICA*A9, HLA-B*46 and MICA*A5, HLA-B*51 and MICA*A6, HLA-B*52 and MICA*A6, and HLA-B60 and MICA*A5.1, were observed. HLA-B*48 was linked to MICA*A5, MICA*A5.1 and MICA*Del. HLA-B*5801-MICA*A10 linkage was found in a family. Our data indicated a high degree of haplotypic diversity and strong linkage disequilibrium between MICA-STR and HLA-B in a southern Chinese Han population, the data will inform future studies on anthropology, donor-recipient HLA matching in clinical transplantation and HLA-linked disease association.

Asian People↗
PubMed2005

Reveal protein molecular structural-chemical differences between two types of winterfat (forage) seeds with physiological differences in low temperature tolerance using synchrotron-based Fourier transform infrared microspectroscopy.

Winterfat (Krascheninnikovia lanata) (forage seed) is a long-lived native shrub with superior forage quality for livestock and wildlife. The objectives of this study were to use advanced synchrotron technology [S-Fourier transform infrared microspectroscopy (FTIR)] as a novel approach to reveal protein molecular structural-chemical differences in terms of protein secondary structures between the two types of winterfat (forage) seeds, which show physiological differences in low-temperature tolerances. This experiment was performed at beamline U10B at the National Synchrotron Light Source (NSLS) in Brookhaven National Laboratory (BNL), U.S. Department of Energy (NSLS-BNL, New York). The results showed that with the synchrotron analytical technique (S-FTIR), the molecular structural-chemical makeup and characteristics of the winterfat seed tissues could be imaged and revealed. The protein secondary structures differed between the large and the small seed tissues. By using the multicomponent peaks modeling method, the results show that the large seeds contained no significant differences (P > 0.05) in percentage of beta-sheet (average 37.0%) and alpha-helix (average 24.1%). However, the large seeds contained a lower (P < 0.05) percentage of beta-turns (18.1 vs 20.1%) and a lower (P < 0.05) ratio of beta-turns to alpha-helices (0.8 vs 0.9) and beta-turns to beta-sheets (0.5 vs 0.6). Our results demonstrate the potential of highly spatially resolved synchrotron-based FTIR microspectroscopy to reveal differences of structural molecular chemistry and protein secondary structures, which are associated with seed size variation and may affect germination behaviors.

Amaranthaceae↗
PubMed2005

Molecular chemistry imaging to reveal structural features of various plant feed tissues.

Synchrotron Fourier transform infrared (FTIR) microspectroscopy as a rapid, direct, and non-destructive analytical technique can explore molecular chemical features of the micro-structure of biological samples. However, the application of this synchrotron technology to feed science and feed chemistry is extremely rare. This article reviews that with synchrotron FTIR microspectroscopy, the molecular chemistry of various feed tissues could be imaged. These images revealed spatial intensity and distribution of chemical functional groups in various feeds tissues within cellular dimensions. Such information can be used for plant breeding program for selecting superior variety of plant for targeted feed purposes and for prediction of feed quality and nutritive value. The final purpose of this article shows that Synchrotron FTIR microspectroscopy can be used for biological structure study.

Plants, Edible↗
PubMed2005

Single nucleotide polymorphisms in the corticotrophin-releasing hormone and pro-opiomelancortin genes are associated with growth and carcass yield in beef cattle.

A single nucleotide polymorphism (SNP) in the corticotrophin-releasing hormone gene (CRH C22G) alters the fourth amino acid in the signal sequence from proline to arginine. Two other SNPs (CRH A145G and C240G) occur in the propeptide region at residue positions 45 and 77, respectively, that result in serine/asparagine and histidine/aspartic acid substitutions respectively. These SNPs, as well as SNPs in pro-opiomelancortin (POMC), leptin (LEP) and melanocortin-4 receptor (MC4R), were evaluated for associations with average daily gain, end-of-test rib-eye area, shipping weight and hot carcass weight in a group of 256 steers using a general linear model. The CRH C22G SNP was associated with end-of-test rib-eye area (P < 0.034) and hot carcass weight (P < 0.0015). The SNP in POMC was associated with shipping weight (P < 0.0078) and hot carcass weight (P = 0.006) while it approached significance for average daily gain (P < 0.07). The SNP in MC4R approached significance for hot carcass weight (P < 0.085) while no significance was observed between the leptin SNP and the above listed traits. Because both CRH and POMC regulate appetite, potential interaction effects between these two genes were assessed. The absence of an interaction effect between CRH and POMC with hot carcass weight suggests that these genes act independently to increase carcass yield. These gene effects used singularly or together could result in an economic benefit to the beef industry.

Animals↗
PubMed2005

Improving the nutritional value of oat hulls for ruminant animals with pretreatment of a multienzyme cocktail: in vitro studies.

Relatively high amounts of hydroxycinnamic acid in oat hulls, mainly ferulic acid, are believed to be inhibitory to digestion by ruminal microorganisms. Ferulic acid is produced via the phenylpropanoid biosynthetic pathway and covalently cross-linked to polysaccharides by ester bonds and to components of lignin, mainly by ether bonds. Ferulic acid also forms dimers or trimers. As a result, polysaccharides become extensively cross-linked by ferulate dimerization or trimerization and incorporation into lignin. Previous studies have shown that Aspergillus ferulic acid esterase and Trichoderma xylanase act synergistically to release ferulic acid from feruloyl-polysaccharides in complex plant cell walls of oat hulls. This activity opens the remainder of the polysaccharides to further hydrolytic attack and facilitates the accessibility of the main polysaccharide chain to cellulase, thereby increasing the release of reducing sugars. In Exp. 1, the best multienzyme cocktail (ferulic acid esterase, xylanase, cellulase, endo-glucanase [I, II], and beta-glucanase) was developed using an orthogonal experimental design, L25 (5(6)), where L = orthogonal table; 6 = factors; 5 = five levels of each; and 25 = experimental number, for further in situ and/or in vivo study. In Exp. 2, in vitro biodegradation studies with a 3 x 2 x 4 factorial arrangement of treatments were used to evaluate the responses of three feedstuffs, oat hulls or standard references (wheat straw and alfalfa hay), two particle sizes (1 mm and 250 microm), and four in vitro incubation treatments with the best multienzyme cocktail developed in Exp. 1. Addition of the multienzyme cocktail to the forages improved (P < 0.01) in vitro ruminal fluid degradability. With respect to feedstuff, the order of response (P < 0.05) to the treatments was oat hulls (+12% unit) > wheat straw (+5% unit) > alfalfa (+2% unit). This multi-enzyme cocktail seems best suited for oat hulls containing feruloyl ester bonds. In conclusion, data from this study suggest that the addition of the multienzyme cocktail to poorly digestible feeds before feeding enhanced degradation of DM.

Animal Feed↗
PubMed2004

Time-dependent speckle in holographic optical coherence imaging and the health of tumor tissue.

Holographic optical coherence imaging acquires en face images from successive depths inside scattering tissue. In a study of multicellular tumor spheroids the holographic features recorded from a fixed depth are observed to be time dependent, and they may be classified as variable or persistent. The ratio of variable to persistent features, as well as speckle correlation times, provides quantitative measures of the health of the tissue. Studies of rat osteogenic sarcoma tumor spheroids that have been subjected to metabolic and cross-polymerizing poisons provide quantitative differentiation among healthy, necrotic, and poisoned tissue. Organelle motility in healthy tissue appears as super-Brownian laser speckle, whereas chemically fixed tissue exhibits static speckle.

Animals↗
PubMed2004

Screening and analysis of porcine endogenous retrovirus in Chinese Banna minipig inbred line.

Pigs have been the most likely animal as the source of cells, tissues, and organs for xenotransplantation. But the use of pigs in xenotransplantation is associated with the risk of porcine endogenous retrovirus (PERV) transmission. Previous studies have identified that the proviruses are integrated into the genome of normal pigs and that virus particles released from the porcine cells can infect human cells in vitro. As a unique inbred pig, Banna minipig inbred (BMI) has a huge potential value for xenotransplantation and medical research. It has been the focal experimental animal for pig-to-human xenotransplantation in China, due to its clear genetic background and tiny individual differences. To evaluate whether the potential risk of PERV exists in inbred pigs, a series of screening experiments were performed herein. The results of PCR with primers specific for gag, pol, and env showed that proviruses existed in the genome of BMI, and the PERV subtypes were PERV-A and PERV-B. PERV mRNA was expressed functionally in BMI. Positive results of an RT assay identified that PERV in BMI had potential infectivity, but the concentration of PERV reverse transcriptase in BMI was almost 20 times lower than that of HIV. These results suggested that gag, pol and env genes of PERV were not lost during inbreeding, which created favorable conditions to produce viral particles that could possibly infect human cells in xenotransplantation.

Animals↗
PubMed2004

Phylogenetic analysis of porcine endogenous retrovirus variation in three Chinese pigs.

PCR amplification was performed on genomic DNA extracted from peripheral blood lymphocytes of three species of Chinese pigs (Banna minipig inbreed [BMI], Wu-Zhi-Shan pig [WZSP], and Nei jiang pig [NJP]), using primers corresponding to the highly conserved regions of polymerase (pol) gene. Extracted PCR products were then cloned in a pGEM-T vector. Phylogenetic analysis of the nucleotide sequences of BMI-PERV, NJJP-PERV, and WZSP-PERV revealed them to be a novel category of PERV. In comparison to other type C retrovirus and lentivirus, their amino acid sequenced show about 30% to 57.7% identities. Our previous research demonstrated that PERV in the three pigs was highly expressed. It appears likely that functional loci encoding these novel PERV sequences exist, but this remains to be established. The novel sequences described in this report will allow such investigations to be actively pursued.

Animals↗
PubMed2004

Application of advanced synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy to animal nutrition and feed science: a novel approach.

Synchrotron radiation-based Fourier transform IR (SR-FTIR) microspectroscopy has been developed as a rapid, direct, non-destructive and bioanalytical technique. This technique, taking advantage of synchrotron light brightness and a small effective source size, is capable of exploring the molecular chemistry within the microstructures of a biological tissue without the destruction of inherent structures at ultraspatial resolutions within cellular dimensions. This is in contrast to traditional 'wet' chemical methods, which, during processing for analysis, often result in the destruction of the intrinsic structures of feeds. To date there has been very little application of this technique to the study of feed materials in relation to animal nutrient utilisation. The present article reviews four applications of the SR-FTIR bioanalytical technique as a novel approach in animal nutrition and feed science research. Application 1 showed that using the SR-FTIR technique, intensities and the distribution of the biological components (such as lignin, protein, lipid, structural and non-structural carbohydrates and their ratios) in the microstructure of plant tissue within cellular dimensions could be imaged. The implication from this study is that we can chemically define the intrinsic feed structure and compare feed tissues according to spectroscopic characteristics, functional groups, spatial distribution and chemical intensity. Application 2 showed that the ultrastructural-chemical makeup and density of yellow- and brown-seeded Brassica rape could be explored. This structural-chemical information could be used for the prediction of rapeseed quality and nutritive value for man and animals and for rapeseed breeding programmes for selecting superior varieties for special purposes. More research is required to define the extent of differences that exist between the yellow- and brown-seeded Brassica rape. Application 3 showed with the SR-FTIR technique that chemical differences in the ultrastructural matrix of endosperm tissue between Harrington (malting-type) and Valier (feed-type) barley in relation to rumen degradation characteristics could be identified. The results indicated that the greater association of the protein matrix with the starch granules in the endosperm tissue of Valier barley may limit the access of ruminal micro-organisms to the starch granules and thus reduce the rate and extent of rumen degradation relative to that of Harrington barley. It is the first time that the microstructural matrix in the endosperm of barley has been revealed by using the SR-FTIR technique, which makes it possible to link feed intrinsic structures to nutrient utilisation and digestive behaviour in ruminants. Application 4 showed with the SR-FTIR technique that the chemical features of various feed protein (amide I) secondary structures (such as feather, wheat, oats and barley) could be quantified. With a multi-component fitting program (Lorentz function), the results showed feather containing about 88% beta-sheet and 4% alpha-helix, barley containing about 17% beta-sheet and 71% alpha-helix; oats containing about 2% beta-sheet and 92% alpha-helix; and wheat containing about 42% beta-sheet and 50% alpha-helix. The relative percentage of the two may influence protein value. A high percentage of beta-sheet may reduce the access of gastrointestinal digestive enzymes to the protein structure. Further study is required on feed protein secondary structures in relation to enzyme accessibility and digestibility. In conclusion, the SR-FTIR technique can be used for feed science and animal nutrition research. However, the main disadvantage of this technique is the requirement for a special light source; a synchrotron beam.

Animal Feed↗
PubMed2004

Nutrient supply to dairy cows from processed white lupines.

The objective of this study was to compare the DVE/OEB system (DVE = truly absorbed protein in the small intestine; OEB = degraded protein balance (DPB) in Dutch) and the NRC-2001 model in the prediction of supply of protein to dairy cows from processed white lupines (Lupinus albus L.). Comparisons were made in terms of (1) ruminally synthesized microbial CP, (2) truly absorbed protein in the small intestine, and (3) degraded protein balance. In addition, the systematic investigation of roasting of the white lupines at various temperatures (110, 130, or 150 degrees C) and times (15, 30 or 45 min) on manipulation of digestive behaviour and the potential nutrient supply to dairy cows were also carried out, to obtain information on best processing conditions as intestinal protein sources (to achieve target values for potential high net absorbable protein in the small intestine while holding any N loss in the rumen to a low level). The results showed that the predicted values from the DVE/OEB system and the NRC-2001 model had significant correlations with high R ( > 0.83) values. However, using the DVE/OEB system, the overall average microbial protein supply based on available energy was 11% higher and the truly absorbed protein in the small intestine was 7% higher than that predicted by the NRC-2001 model. The difference was also found in the prediction of the degraded protein balances (DPB), which was 8% higher based on data from the NRC-2001 model. These differences are due to considerably different factors used in calculations in the two models, although both are based on similar principles. This indicates that a further refinement is needed for a modern protein evaluation and prediction system. In addition, this study showed that the roasting at higher temperature and time was effective in shifting protein degradation from rumen to intestines and it increased the DVE or MP values without reaching the negative degraded protein balance. The processing at 15 degrees C for 30 or 45 min might be the best treatments for white lupine due to its higher DVE and MP values and the very low DPB values.

Animal Feed↗
PubMed2004

Effects of alfalfa particle size and specific gravity on chewing activity, digestibility, and performance of Holstein dairy cows.

Two experiments were carried out to test the effects of alfalfa particle size and functional specific gravity (FSG) on chewing activity, digestibility, rumen kinetics, and production of lactating dairy cows fed corn silage based rations. In experiment 1, water-holding capacity (WHC), insoluble dry matter, hydration rate, and FSG changes were determined in alfalfa hay (varying in particle size) and corn silage. Reduction of particle size increased bulk density, FSG, and the rate of hydration, and decreased WHC of alfalfa. In experiment 2, 9 midlactation Holstein dairy cows fed total mixed rations containing 3 sizes of alfalfa hay (with geometric mean 7.83, 4.04, and 1.14 mm) were used in a replicated 3 x 3 Latin square design. The diets contained 20, 20, 35, 7, 7.5, 10, 0.3, 0.1, and 0.1% of DM alfalfa, corn silage, barley, soybean meal, beet pulp, wheat bran, dicalcium phosphate, vitamin premix, and salt, respectively. The geometric means (GM) of rations were 3.34, 2.47, and 1.66 mm in long, medium, and fine alfalfa treatments, respectively. Reduction of particle size increased daily NDF intake (kg), but decreased the proportion of physically effective factor (pef) and physically effective NDF (peNDF) in the ingested rations. Reduction of particle size increased the FSG of rations and intake of DM but reduced digestibility of NDF and ash. Reduction of particle size decreased ruminal mean retention time (RMRT), but increased the ruminal particulate passage rate. Milk and FCM yield were not affected by treatments. The rumen pH, total chewing activity, rumination, eating time, and milk fat were reduced as particle size decreased, but milk protein increased. This study showed that reduction of forage particle size increased bulk density, FSG, and hydration rate of alfalfa and was the most influential factor affecting DMI, milk composition, and chewing behavior. Reduction of forage particle size had minimal impact on digestibility and milk production.

Animal Feed↗
PubMed2003

Ultrasound detection through turbid media.

Optical coherence-domain reflectometry and laser-based ultrasound detection have been combined with the use of adaptive optics to detect ultrasound through turbid media. The dynamic hologram in a photorefractive quantum-well device performs as a coherence gate that eliminates multiply scattered background. Quadrature homodyne detection conditions are selected by the choice of center wavelength of the pulse spectrum, requiring no active stabilization or feedback. A depth resolution of 30 microm was achieved, with a pulse duration of nominally 120 fs for ultrasound detection through turbid media up to optical thicknesses of 11 mean free scattering lengths.

Holography↗