Biomedical subjects

W Sun

Publications and source records attributed to W Sun.

At least 307 records · Page 17Linked to original sources

PubMed1992

Endothelial cell adhesion on polyurethanes containing covalently attached RGD-peptides.

Peptides based on cell-adhesive regions of fibronectin, Arg-Gly-Asp-Ser (RGDS), and vitronectin, Arg-Gly-Asp-Val (RGDV), were covalently bound to a polyurethane backbone via amide bonds. Nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopies were used to monitor the reactions. The amount of grafted peptide was determined by amino acid analysis. X-ray photoelectron spectroscopy (XPS) suggested the presence of the grafted peptide at the polymer-air interface in vacuo. Dynamic contact angle analysis showed that, in water, the peptide-grafted polyurethane surfaces were more polar than the underivatized polyurethane indicating enrichment of peptide groups at the surface. The attachment and spreading of human umbilical vein endothelial cells (HUVECs) on the underivatized and peptide-grafted polyurethanes was investigated. The GRGDSY- and GRGDVY-grafted substrates supported cell adhesion and spreading even without serum in the culture medium. The GRGDVY-grafted substrate supported a larger number of adherent cells and a higher extent of cell spreading than the GRGDSY-grafted substrate. These RGD-containing peptide-grafted polyurethane copolymers may be useful in providing an easily prepared cell-adhesive substrate for various biomaterial applications.

Amino Acids↗

PubMed1992

Estrogen negatively regulates rat gonadotropin releasing hormone (rGnRH) promoter activity in transfected placental cells.

To dissect the functional architecture of the rat gonadotropin releasing hormone (GnRH) gene promoter and its regulation by estrogen, gene transfer studies were performed in a placental cell line. 5'-Deletional constructs demonstrated that cis-acting elements important for rGnRH promoter activity in placenta were contained within a region of the proximal promoter between -73 and -16 bp upstream of the transcription initiation site. In addition, an inhibitory region was found from -903 to -424. Deletion of sequences to -424 which removed the inhibitory region, produced a promoter fragment which exhibited a 50% inhibition of GnRH promoter activity in the presence of estrogen (E) and cotransfected estrogen receptor. Negative regulation by E was retained in constructs deleted to -73 bp. We conclude that sequences important for placental cell expression and estrogen regulation of rGnRH lie within the region from -73 to -16. In addition, potential repressor sequences active in placental cells are present between -903 to 424.

Animals↗

PubMed1992

Mapping of a human brain voltage-gated calcium channel to human chromosome 12p13-pter.

Degenerate DNA oligomers coding for highly conserved regions of the voltage-gated calcium channel were synthesized for the polymerase chain reaction (PCR) using DNA from a human brain cDNA library as template. PCR amplified a 640-bp DNA fragment from the human brain cDNA library. Sequencing revealed that this fragment encodes part of a protein highly homologous to a subtype of the dihydropyridine-sensitive calcium channel cloned from rabbit heart and rat brain. Southern analysis of panels of somatic cell hybrids mapped the 640-bp fragment, CACNL1A1, to human chromosome 12p13-pter.

Amino Acid Sequence↗

PubMed1992

Digestion and performance responses to lasalocid and concentrate supplements by beef cattle fed bermudagrass hay.

Beef cattle consuming bermudagrass hay were not supplemented or received a limited amount of ground corn alone or with a mix of protein meals to determine influences of concentrate supplementation on digestion and performance when the ionophore lasalocid (200 mg daily) was given. With limited feed intake, supplement treatment did not change the acetate to propionate shift in beef cows occurring with lasalocid (P < 0.06). Lasalocid did not affect sites of digestion of organic matter or nitrogen with any supplement treatment. However, lasalocid decreased (P < 0.10) ruminal digestion of neutral and acid detergent fibre. Live-weight gain by growing beef calves ingesting bermudagrass hay ad libitum was higher (P < 0.05) with than without supplementation and tended (P < 0.12) to be greater for corn plus protein meals than for corn alone. Lasalocid did not affect or interact with supplement treatment in feed intake or live-weight gain of heifers (236 kg; no growth stimulant) or steers (237 kg; treated with 200 mg progesterone and 20 mg estradiol benzoate). Lasalocid at 200 mg daily did not improve digestion characteristics or influence performance by beef cattle consuming a Basal diet of bermudagrass hay. Further, effects of lasalocid were not modulated by supplementation with concentrate, concentrate type or sex or growth stimulant usage.

Animal Feed↗

PubMed1992

CD4 lymphocyte decline and survival in human immunodeficiency virus infection. The Military Medical Consortium for Applied Retroviral Research.

The loss of the CD4 lymphocyte is the central pathophysiologic event in the progression of human immunodeficiency virus (HIV) infection. This retrospective study, based on review of data from deceased HIV patients followed in a single HIV clinic, was conducted to determine if the rate of CD4 lymphocyte decline was predictive of survival. Forty of 172 patients met defined criteria for inclusion in this study. For each patient, CD4-cell counts showed approximate exponential decline over time. A Cox regression analysis was used to assess the association of CD4 cell decline (half-life), race, age, gender, initial CD4-cell count, and treatment (anti-Pneumocystis carinii pneumonia prophylaxis and/or zidovudine vs. no therapy) on total survival (from initial CD4 cell count) and on remaining survival time after reaching a CD4 cell count of 100 (estimated). For all patients, the rate of CD4 cell decline was predictive of total survival (p = .009) but not for survival after reaching a count of 100 (p = .6). For patients who had never received therapy (6 patients), however, the CD4 half-life remained associated with survival time from 100 CD4 cells (p < .05) as opposed to the treated patients. Therapy was the single variable most predictive of both survival endpoints, resulting in an increase in median total survival of 27.2 mo (p < .00001) and of 15.4 mo from a CD4 cell count of 100 (p < .00004). Nonwhites had a slight survival disadvantage compared to whites (p = .08 overall; p = .02 from CD4 cell count of 100).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Digestion, feed intake, and live weight gain by cattle consuming bermudagrass hay supplemented with whey.

Three experiments were conducted with cattle consuming bermudagrass hay to determine whether low-level supplements of whey alone, corn alone, or whey plus corn affect feed intake, digestion, and(or) BW gain. Six ruminally and duodenally cannulated beef cows (574 kg), used in a Latin-square trial (Exp. 1), were fed bermudagrass hay without supplementation (control) or with 2.8% whey (low whey, LW), 5.6% whey (high whey, HW), 17.4% ground corn (C), 2.8% whey plus 14.9% corn (C-LW), or 5.6% whey plus 12.4% corn (C-HW). Supplementing with whey and(or) corn increased ruminal butyrate (8.8, 9.4, 10.0, 9.6, 10.5, and 11.0 mol/100 mol of total VFA for control, LW, HW, C, C-LW, and C-HW, respectively; SE = .20). Supplements did not affect microbial N flow at the duodenum. Six Holstein steer calves (158 kg) in a Latin square (Exp. 2) consumed bermudagrass hay ad libitum alone (control) or with .075 or .15% BW whey (LW and HW, respectively), .5% BW ground corn (C), or corn-whey mixes made by substituting whey for corn (C-LW and C-HW). Substituting .15% BW of whey for corn increased (P less than .05) total OM intake slightly (3.99, 3.84, 3.75, 4.11, 4.28, and 4.47 kg for control, LW, HW, C, C-LW, and C-HW, respectively; SE = .10). In an 84-d randomized block experiment (Exp. 3), 96 beef calves (194 kg) consumed (ad libitum) low-quality bermudagrass hay alone or with C, LW, HW, C-LW, or C-HW supplements.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1992

[Effect of electro-acupuncture on cortical and hippocampal EEG in adjuvant arthritis rats].

Adjuvant arthritis (AA) rats were used as the chronic pain model. The cortical and hippocampal (HPC) EEG were recorded. The behaviour and local inflammatory reaction were observed. The results showed an arousal response of desynchronization of the ECoG and HPC EEG in the AA rats, the delta waves were decreased and beta waves increased significantly. However, the inhibited effect to the desynchronization were showed could be inhibited by the electro-acupuncture (EA) on bilateral Zusanli points and morphine in the AA rats. The results suggested that the cortex and hippocampus participate in the modulating action of chronic pain, and the EA has an analgesic action.

Acupuncture Analgesia↗

PubMed1992

[A study of the regularity of pain threshold changes after trauma and the effect of electroacupuncture].

Pain threshold of rats was measured by the latent period of tail flick and limb withdrawal elicited by radiant heat. 52 male SD rats were used and trauma was produced by aseptic amputation just beneath the right ankle joint. The effect of nerve block and electroacupuncture (EA) was studied and non-traumatic groups were arranged as control. The pain threshold was reduced right after trauma and the lowest level appeared on the 3rd day and then recovered gradually up to the 7th day after trauma. Nerve block and EA markedly raised the pain threshold. Particularly, EA elevated pain threshold of traumatic rats more marked and long-lasted than the effect of nerve block. This may be resulted by mobilizing the functions of the endogenous analgesic systems.

Acupuncture Analgesia↗

PubMed1992

Partition coefficient of luciferase from photobacteria in PEG/salt two aqueous phase system.

The relationship between the logarithmic partition coefficient (K) of luciferase of photobacteria and PEG MW in the PEG/salt two aqueous phase system was shown to be a linear function. The hydrophilic PEG of lower MW facilitated the partition of luciferase into the top PEG-riching phase and gave a higher K value, while PEG of higher MW, its hydrophobic characteristic, made more enzyme partition into the bottom salt-riching phase and lower K value was obtained. In the PEG/trivalent salt system, such as phosphate and citrate, there was a turning-point on the linear relation between the log K and the PEG MW, but which never appeared if a divalent salt such as sulfate, succinate or tartrate was used in the system. When the system was composed of homogeneous PEG and ammonium sulfate, the K value was increased with the increment of the salt concentration, but after the salt concentration had reached at certain level, the K value was uninfluenced. When two kinds of PEG with different MW were used in this system a minimal K value appeared at certain concentration of ammonium sulfate, and the K value was raised when the salt concentration was either increased or decreased. Neither the proportion of the two kinds of PEG nor their total concentration used in the system showed any effect on the above patterns, although the K value may give some corresponding changes. (ABSTRACT TRUNCATED AT 250 WORDS)

Ammonium Sulfate↗

PubMed1992

[Location of ctDNA fragment related to CMS in Brassica napus L. var. xiangai].

The ctDNA of sterile line and its maintainer from Brassica napus L. var. xiangai were digested by restriction endonucleases EcoRI, BamHI, PstI and SmaI. Only one special fragment E3.2kb was observed in EcoRI restriction pattern of maintainer. After being eluted, this fragment was incubated with plasmid pUC9 and then transformed E. coli JM83. Through colour screening, clony hybridization and electrophoretic analyses, the special clone carrying E3.2 was obtained. The rRNA gene probe was used to hybridize with the EcoRI restriction pattern. The result showed that E3.2kb fragment is homologous to rRNA gene. And then, we use E3.2 fragment as probe to hybridize with rRNA gene digested by BamHI, EcoRI, SalII, BglII, HindIII and PstI. According to rRNA gene map, E3.2 fragment was located at the leader sequence of 16S rRNA gene, from +2.0kb to +5.4kb. Because this 3.4kb region was in the inverted repeat region of ctDNA and it is homologous to E3.2kb that related to CMS. So probably CMS is related to this 3.4kb region in the inverted repeat region of ctDNA.

Brassica↗

PubMed1992

Effect of low benzene exposure on neurobehavioral function, AChE in blood and brain and bone marrow picture in mice.

The purpose of this study was to examine the effect of low level benzene exposure on neurobehavioral functions, AChE in blood and brain, bone marrow picture in Kunming mice. Forty adult Kunming male mice were divided into 4 groups. They were exposed to 12.52, 3.13, 0.78 and 0 ppm benzene for 2 h.d-1 for 30 d. Central nervous system (CNS) function was inhibited by 12.52 ppm and excited by 0.78 ppm benzene exposure, but irregularly affected by 3.13 ppm. AChE in blood and brain was decreased in 12.52, 3.13 ppm group. The weight of liver to body weight ratios in 12.52 ppm group was higher than those of control group significantly. Bone marrow picture revealed inhibited proliferation of white and red cell systems, especially in 12.52 ppm group, consisting of decrease of percentage of myeloblast, premyelocytes, myelocytes, erythroblasts and megakaryocytes, especially in 12.52 ppm group.

Acetylcholinesterase↗

PubMed1991

Digestion in steers and lactational performance of Jersey cows fed diets varying in natural protein level continuously or on alternate days.

Five crossbred beef steers (515 kg) were used in a Latin square experiment and 36 lactating Jersey cows (12 primiparous, 310 kg; 24 multiparous, 365 kg) were used in a completely randomized design study to determine effects on characteristics of digestion and lactational performance of daily alternation of the dietary level of natural protein (NP). In Experiment 1, steers were fed diets of 50% bermudagrass hay and 50% concentrate. Concentrate was approximately 18% crude protein (CP), formulated to be 60, 80 or 100% NP (varying proportions of soybean meal, urea and ground corn), and was fed at 1.5% body weight (dry matter basis). These concentrates were fed daily or ones with 60 and 100% NP were fed on alternate days. Alternate day feeding did not markedly affect characteristics of digestion, including ruminal escape of feed protein, and NP level of concentrate fed continuously had no effects either. In Experiment 2, cows were subjected to treatments similar to those in Experiment 1, and performance on d 20-40 of lactation was measured. Concentrate was given at 1 kg (as fed)/2.15 kg milk produced, yielding a dietary concentrate level of approximately 40% (dry matter basis). Alternate feeding depressed (P less than 0.05) overall milk fat percentage. Alternate feeding increased production of milk and protein and body weight of primiparous cows but caused little change with multiparous cows. Besides increasing the dietary level of concentrate, perhaps alternate feeding regimes have utility to lower milk fat level without impairing milk production. Level of NP in concentrate fed continuously did not affect performance by multiparous cows though primiparous cow performance was generally enhanced, possibly because CP intake was adequate for multiparous cows but marginal for primiparous cows. However, overall, efficiency of production of solids-corrected milk rose slightly with increasing NP.

Ammonia↗

PubMed1991

Relationships of body weight, forage composition, and corn supplementation to feed intake and digestion by Holstein steer calves consuming bermudagrass hay ad libitum.

Holstein steer calves (101 to 350 kg BW) consumed bermudagrass hay ad libitum without or with supplemental ground corn up to 1.0% of BW. As BW increased, total DMI increased quadratically (-2.459 + .05448 [BW]-.000073 [BW2] + .540 [corn DMI]; R2 = .83, sy.x = .655). Each kilogram of corn DM decreased bermudagrass DMI by .46 kg. Total digestible OM intake (kg) increased with BW and corn supplementation (.314 + .0127 [BW] + .441 [corn OM intake]; R2 = .79, sy.x = .444). Feed intake level accounted for approximately 2.5 times more variability in total digestible OM intake than digestion did. Corn supplementation decreased digestion of bermudagrass NDF (62.50 - 8.468 [corn DMI, % BW]; R2 = .13, sy.x = 8.121), with a similar decrease across BW. Increasing bermudagrass DMI (% of BW) decreased bermudagrass NDF digestion slightly, but variation accounted for was only 33% of that attributable to corn DMI (% of BW). Concentrations of common fiber fractions (NDF, ADF, cellulose, hemicellulose, and ADL) in bermudagrass explained very little variation in feed intake and digestion, indicating considerable influence of other factors. Bermudagrass intake and digestion were not related, and no substantial interactions were observed among steer BW, corn level, and bermudagrass composition.

Animal Feed↗

PubMed1991

Feed intake and digestion by Holstein steers fed warm or cool season grass hays with corn, dried molasses, or wheat middlings.

This study determined the effects of adding a small amount of dried molasses to supplemental corn and of supplementing with corn, wheat middlings, or corn-wheat middlings mixture on intake and digestion by Holstein steers fed warn or cool season grass hays. Eight steers (175 kg BW), in two simultaneous Latin squares, were fed, once daily, bermuda-grass (72% NDF) or ryegrass-wheat (58% NDF) hay ad libitum, alone or with approximately .05% BW of dried molasses (with 31% roughage), 5% BW of ground corn, or both. Adding dried molasses to corn decreased feed intake but did not affect digestible OM intake. Total tract digestion of fiber from bermudagrass tended to be enhanced by adding dried molasses to corn. Eight steers (193 kg BW) were used in an experiment with the same design in which similar forages were fed alone or with corn (.5% BW), wheat middlings (.63% BW), or .25% BW of corn plus .31% BW of middlings. Feed intake for both grasses was similar among supplements. Wheat middlings depressed total tract fiber digestion more than corn with both forages. Supplementation with corn depressed fiber digestion slightly more with ryegrass-wheat than with bermudagrass, but wheat middlings had a slightly greater depressing effect on fiber digestion with bermudagrass. Associative effects of mixing corn and wheat middlings in OM digestion and digestible OM intake were negative for bermudagrass and positive for ryegrass-wheat. Interaction among characteristics of basal forage and concentrate modulated feed intake and digestion by ruminants.

Animal Feed↗

PubMed1991

[Identification of Chinese drugs by fluorescence spectrum].

Cortex Fraxini, Radix et Rhizoma Rhei, Semen Astragali Complanati, Semen Lini, Bulbus Fritillariae Cirrhosae, Bulbus Fritillariae Thunbergii and their confused medicinal materials have been identified by the fluorescence spectrum. This is a referential method for the identification of Chinese drugs.

Drug Contamination↗

PubMed1991

[Effects of nicardipine on automaticity of sinoatrial node in rabbit heart].

The dual effects of nicardipine (Nic) on the automatic activity of sinoatrial (SA) node cell in rabbit heart had been observed using intracellular microelectrodes. Superfused with Nic 0.1, 0.5, 1.0, and 5.0 mumol.L-1 for 10 min, the spontaneous rate was decreased by 32%, 42%, 47%, and 69%, respectively. However, by superfusing with Nic 0.05 mumol.L-1, the spontaneous rate and the amplitude of action potentials were increased by 12% and 13% respectively. Nic 5.0 mumol.L-1 inhibited the positive chronotropic effects of isoproterenol and nicotine. The results suggest that Nic may block the calcium influx in SA node cells.

Action Potentials↗

PubMed1991

Calculation on ultrafiltration for pullulan solution.

Ultrafiltration is an important step in isolation and purification of pullulan. Here a new formula for ultrafilter calculation is derived from experiments about the relationship between the ultrafiltrate rate and the concentration of pullulan solution. It can be used for calculating and designing of ultrafilter under defined production scale and its related technical parameters.

Glucans↗

PubMed1991

[Effect of atrial natriuretic factor on the automaticity of sinus node in guinea pig heart].

The effect of atrial natriuretic factor (ANF) on sinoatrial (SA) node cells in guinea pig heart was studied by using intracellular microelectrodes. When the heart superfused with ANF 0.025 and 0.05 mumol/L for 7 min respectively, the spontaneous rate showed no significant changes, but 0.1 mumol/L ANF resulted in a definite decrease by 7% (P less than 0.01). However, when ANF (0.025, 0.05 and 0.1 mumol/L) was superfused along with 0.5 mumol/L isoproterenol, the spontaneous rate was respectively depressed by 4, 12 and 22%. These results indicate that ANF can depress the positive chronotropic effect of isoproterenol. The mechanism of this action may be related to the blocking effect of ANF on T-type calcium channel of SA node.

Action Potentials↗