Biomedical subjects

H Yuan

Publications and source records attributed to H Yuan.

At least 73 records · Page 4Linked to original sources

PubMed2000

Sexual dimorphism of the motoneurons in the human spinal cord.

There have been few morphometric studies on the size of the motoneurons of the human spinal cord. The purpose of the present study is to report the differences in the size of the motoneurons between males and females in the human spinal cord. We examined numbers and transverse cell body areas of the motoneurons of the anterior horn using 16 male and 21 female human spinal cords at levels C5 and L3. The sizes of the motoneurons were larger in males than in females, but their numbers were practically the same. These results can be of great importance in setting standard values for the understanding of morphological and functional correlations.

Aged↗

PubMed2000

Demographic differences in body composition of Navy and Marine Corps personnel: findings from the perception of wellness and readiness assessment.

With the recent increase in women's representation in the military, baseline physical measurement data are needed to help set appropriate accession and retention standards and to design useful prevention and intervention programs in the areas of physical fitness and health. This study incorporated several body composition indices to obtain anthropometric data for a representative sample of 1,292 active duty Navy and Marine Corps women and men. It also assessed the extent to which personnel met weight-for-height and body fat standards. The prevalence of overweight was considerably lower among Marine Corps women compared with Navy women and was slightly less for Marine Corps men compared with their Navy counterparts. Between one-fifth and one-third of military personnel exceeded Navy/Marine Corps weight-for-height standards. Navy women tended to meet weight standards more often than Navy men. Fewer Marine Corps women than men were overweight, but more exceeded their weight-for-height standards.

Adipose Tissue↗

PubMed2000

[Mixotrophic cultivation of Synechocystis sp. 6803: influences of light intensity and glucose].

The growth characteristics and the effects of glucose and light on the growth of Synechocystis sp. PCC6803 under mixotrophic conditions have been investigated. An exponential growth phase had been observed before glucose was consumed. The results showed that both of light intensity and glucose concentration had obvious effects on the mixotrophic growth of Synechocystis sp. PCC6803: the specific growth are decreased with the increase of glucose concentration at light; the specific growth rate and biomass/glucose yield increased with light intensity, ranging from 15-55 microE.m-2.s-1; when light intensity was higher than 55 microE.m-2.s-1, light saturation appeared.

Carbon Dioxide↗

PubMed2000

Heroin abuse and nitric oxide, oxidation, peroxidation, lipoperoxidation.

To further reveal the risks of heroin abuse to human body, and to determine the injuries of oxidation, peroxidation and lipoperoxidation induced by nitric oxide and other free radicals to heroin abusers, we determined and compared plasma values of lipoperoxides (LPO), nitric oxide (NO), vitamin C (VC), vitamin E (VE), beta-carotene (beta-CAR) and erythrocyte values of LPO, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in 114 heroin abusers and 100 healthy volunteers. Using linear regression and correlation as well as stepwise regression and correlation, we also analyzed the effect of the abusing duration, and daily abusing quantity on the above-mentioned biochemical parameters in the heroin abusers. The results showed that, compared with the healthy volunteer groups, the average plasma values of LPO, and NO, and the average erythrocyte value of LPO in the heroin abuser group were significantly increased (P < 0.0001), and the average plasma values of VC, VE, and beta-CAR and the average erythrocyte values of SOD, CAT, and GSH-Px were significantly decreased (P < 0.0001). Analysis of linear regression and correlation showed that with prolonged heroin abusing and with increased daily quantity in the heroin abusers, the plasma values of LPO, and NO, and the erythrocyte value of LPO were gradually increased (P < 0.001), whereas the plasma values of VC, VE, and beta-CAR and the erythrocyte values of SOD, CAT, and GSH-Px were gradually decreased (P < 0.001). Analysis of stepwise regression and correlation indicated that the plasma values of NO, VC and VE were closely correlated with the abusing duration and daily abusing quantity. These results indicate that the balance between oxidation and antioxidation in the heroin abusers was seriously disturbed, and the injuries induced by nitric oxide and other free radicals, through oxidation, peroxidation and lipoperoxidation to the bodies of heroin abusers exacerbated. It is therefore necessary that in abstaining from heroin dependence, the heroin abusers should acquire sufficient quantities of antioxidants such as VC, VE and beta-CAR.

Ascorbic Acid↗

PubMed2000

[Cleft palate repair of infants with 32 cases].

OBJECTIVE: To search a proper time for cleft palate repair. METHODS: Thirty-two patients with unilateral and bilateral cleft palate, aged from 25 days to 3 months, were undergoing the cleft palate repair. The surgical risk was analyzed perioperatively. The speech function and the maxillary development were also evaluated after the operation. RESULTS: All of the cases were successfully repaired with less bleeding, quicker recovery, shorter operative time and less psychological injury. The speech function and the maxillary development were very well. CONCLUSION: A patient, even under 3 months age, could also be a good candidates for cleft palate repairing when the general condition was good.

Age Factors↗

PubMed2000

[Gena types of Shigella enterotoxins of S. flexneri 2a].

OBJECTIVE: To identify homogenous clones of S. flexneri 2a, using gene distribution polymorphism of Shigella enterotoxin 1 (set 1) and Shigella enterotoxin 2 (set 2) in a Shigellosis outbreak caused by S. flexneri 2a. METHODS: In addition to field epidemiological investigation, 43 strains of S. flexneri 2a were determined by polymerase chain reaction (PCR). RESULTS: The 43 strains (1 from food, 1 from a carrier, 41 from patients) were divided into 3 clones (set1 +/set2 + for 39 strains, set1 -/set2 + for 1, set1 +/set2 - for 3 strains). CONCLUSION: This outbreak was caused by S. flexneri 2a. The route of transmission was contaminated-food borne. Some sporadic cases were noticed during the outbreak. The method used in this study was satisfactory to the identification of S. flexneri 2a.

China↗

PubMed2000

[Effect of various assist pumps on recovering the ventricular function].

With the authors' diaphragm pump and pulsatile as well as nonpulastile impeller pumps, and the clinically used Sarns Roller, both left ventricular assist and biventricular assist experiments were performed on mini pigs and calves. The results demonstrate that the pulsatile impeller pump is the best assist pump for recovering the heart function, because it maintains the pulsatility of aortic pressure by heart failure and thus increases the circulation volume, and it enlarges the diastolic pressure so as to increase the perfusion in coronary artery because it has no backflow.

Animals↗

PubMed2000

[Study on spectra pretreatment in near infrared spectroscopy analysis using charger coupled device detector].

The effects of spectra pretreatment method and parameters to signal noise ratio and calibration models quality in near-infrared spectroscopy analysis using charger coupled device(CCD) detector have been studied and discussed. To attain higher signal noise ratio, in the range of 700-1,100 nm, using 2048 pixels CCD, we suggest that the optimal gaps of smoothing first derivative treatment of spectra are 9 points, and the gap of second derivative treatment is 19 points.

English Abstract↗

PubMed2000

[Development of modern near infrared spectroscopic techniques and its applications].

The historical progresses, characteristics and determined principle of near infrared spectroscopy are presented briefly. The development of modern near infrared spectroscopic instruments, chemometrics problems and applications are reviewed. Some results developed on instrument, chemometrics methods and applications of petroleum industries in our laboratory are presented briefly.

Spectroscopy, Near-Infrared↗

PubMed1999

Stabilization of liposomal membranes by thermozeaxanthins: carotenoid-glucoside esters.

Thermozeaxanthins (TZS) are novel carotenoid-glucoside esters existing in the cell membranes of the thermophilic bacterium, Thermus thermophilus. The effect of TZS on membrane permeability was studied by measuring the leakage of the fluorescent dye from calcein-entrapped large unilamellar liposomes (LUVs). The LUVs were composed of a small portion (0.2-1.0 mol%) of TZS and phosphatidylcholine (PC) of various length and saturation degree of hydrocarbon chains. Incorporation of TZS in egg PC LUVs stabilized the liposomes in the temperature range from 30 to 80 degrees C, as only 2.6% of the entrapped calcein leaked out in contrast to 10% release from the egg PC liposomes without TZS. LUVs composed of dipalmitoylphosphatidylcholine (DPPC) or dioleoylphosphatidylcholine (DOPC) were stabilized by the incorporation of TZS at a temperature below 30 degrees C. Inclusion of TZS in LUVs composed of dimyristoylphosphatidylcholine, whose hydrocarbon chains are shorter than both DPPC and DOPC, did not stabilize the liposomes. About 90% of the entrapped dye was lost indicating defects of the liposomal membranes. Matching of the lipid bilayer thickness with the molecular length of TZS in the bilayers is discussed.

Carotenoids↗

PubMed1999

Suppression of glycogen synthase kinase activity is not sufficient for leukemia enhancer factor-1 activation.

Glycogen synthase kinase-3 (GSK) can be regulated by different signaling pathways including those mediated by protein kinase Akt and Wnt proteins. Wnt proteins are believed to activate a transcription factor leukemia enhancer factor-1 (LEF-1) by inhibiting GSK, and Akt was shown to phosphorylate GSK and inhibit its kinase activity. We investigated the effect of an activated Akt on the accumulation of cytosolic beta-catenin and LEF-1-dependent transcription. Although the activated Akt, mAkt, clearly inhibited the kinase activity of GSK, mAkt alone did not induce accumulation of cytosolic beta-catenin or activate LEF-1-dependent transcription. On the contrary, coexpressed Wnt-1 and Frat activated LEF-1 but did not show significant inhibition of GSK-mediated phosphorylation of a peptide substrate. However, mAkt could act synergistically with Wnt-1 or Frat to activate LEF-1. In addition, the interaction of GSK for Axin appeared to decrease in the presence of mAkt, whereas the interaction for Frat remained unchanged. Consistently, a GSK mutant with substitution of a Phe residue for residue Tyr-216, which showed one-fifth of kinase activity of the wild-type GSK, exhibited a reduced association for Axin than the wild-type GSK. These results suggest that inhibition of GSK kinase activity is not sufficient for activation of LEF-1 but may facilitate the activation by reducing the interaction of GSK for Axin. The additional mechanism for LEF-1 activation may require dissociation of GSK from Axin as Frat facilitates the dissociation of GSK from Axin.

3T3 Cells↗

PubMed1999

Axin and Frat1 interact with dvl and GSK, bridging Dvl to GSK in Wnt-mediated regulation of LEF-1.

Wnt proteins transduce their signals through dishevelled (Dvl) proteins to inhibit glycogen synthase kinase 3beta (GSK), leading to the accumulation of cytosolic beta-catenin and activation of TCF/LEF-1 transcription factors. To understand the mechanism by which Dvl acts through GSK to regulate LEF-1, we investigated the roles of Axin and Frat1 in Wnt-mediated activation of LEF-1 in mammalian cells. We found that Dvl interacts with Axin and with Frat1, both of which interact with GSK. Similarly, the Frat1 homolog GBP binds Xenopus Dishevelled in an interaction that requires GSK. We also found that Dvl, Axin and GSK can form a ternary complex bridged by Axin, and that Frat1 can be recruited into this complex probably by Dvl. The observation that the Dvl-binding domain of either Frat1 or Axin was able to inhibit Wnt-1-induced LEF-1 activation suggests that the interactions between Dvl and Axin and between Dvl and Frat may be important for this signaling pathway. Furthermore, Wnt-1 appeared to promote the disintegration of the Frat1-Dvl-GSK-Axin complex, resulting in the dissociation of GSK from Axin. Thus, formation of the quaternary complex may be an important step in Wnt signaling, by which Dvl recruits Frat1, leading to Frat1-mediated dissociation of GSK from Axin.

Adaptor Proteins, Signal Transducing↗

PubMed1999

Determination of lead in blood and urine by SPME/GC.

Lead is the most frequently quantitated toxic metal in biological matrixes. In this paper, a method is described for lead determination in whole blood and urine using solid-phase microextraction (SPME) gas chromatography. Lead ion is first derivatized with sodium tetraethylborate to form tetraethyllead, which is then extracted from the headspace over the sample by SPME. The analytical procedure was optimized for coating selection, pH, extraction time, and effect of salt. The relative standard deviation was less then 10% for both urine and blood samples. The limit of detection was 3 and 4 ppb; the limit of quantification is 5 and 10 ppb for urine and blood samples, respectively. Good linearity was found for both urine and blood samples when PDMS coating was used. The standard addition method was used for quantitation. Certified urine and blood samples were analyzed, and good accuracy was obtained.

Borates↗

PubMed1999

Recombinant adenovirus is an appropriate vector for endocytotic protein trafficking studies in cultured neurons.

Endocytosis of full-length beta-amyloid precursor protein (APP) from the plasma membrane contributes to beta-amyloid peptide (Abeta) secretion, and, hence, potentially contributes to the molecular pathogenesis of Alzheimer's disease. We recently have demonstrated that central neuronal APP is endocytosed in a common vesicular compartment with recycling synaptic vesicle integral membrane proteins, but is then sorted away from synaptic vesicles for retrograde transport to the neuronal soma. For this report, we explore whether recombinant adenovirus can be used to modulate APP expression in cultured central neurons to study APP processing by the endocytotic pathway in these cells. Using a replication-deficient recombinant adenovirus that expresses a lacZ reporter (Ad5/CMV-lacZ), we demonstrate high efficiency of transfection (30-35%) at low viral titer (10-20 MOI), with no significant neuronal toxicity or cytoarchitectural change. In addition, we demonstrate that infection with the control virus does not result in re-direction of endogenous neuronal APP from usual endocytotic pathways. We have prepared, using the same genomic background as the control virus, an adenoviral vector that expresses the neuronal isoform of human APP (Ad5/CMV-APP). Infection with Ad5/CMV-APP at 10-20 MOI results in significantly increased immunoreactivity for endocytosed APP with preservation of usual endocytotic trafficking. These results demonstrate that recombinant adenovirus at low titer is an appropriate and effective vector for protein trafficking/processing studies in cultured central neurons.

Adenoviridae↗

PubMed1999

Laparoscopic fusion of the lumbar spine: minimally invasive spine surgery. A prospective multicenter study evaluating open and laparoscopic lumbar fusion.

STUDY DESIGN: Two hundred-forty consecutive patients underwent laparoscopic instrumented interbody fusion using custom-designed instrumentation and BAK (Sulzer Spine Tech, Minneapolis, MN) fusion cages. The surgeries were performed at eight spine centers during U.S. Food and Drug Administration investigational device evaluation clinical trials. This cohort was compared with 591 consecutive patients undergoing open anterior fusion with the same device. OBJECTIVES: To investigate the feasibility and safety of the laparoscopic approach compared with that of open procedures. SUMMARY OF BACKGROUND DATA: In other areas of medicine, advances in laparoscopic surgical procedures have resulted in reduced morbidity, expense, and pain when compared with results of the open counterpart. METHODS: The open anterior procedure was performed using a retroperitoneal approach. The laparoscopic procedure was performed transperitoneally with carbon dioxide insufflation to provide visualization using a 10-mm endoscope. Two hollow, titanium, threaded interbody implants packed with autologous bone were inserted into the diseased interspace. RESULTS: The laparoscopy group had a shorter hospital stay and reduced blood loss but had increased operative time. Operative time improved in the laparoscopy group as surgeons' experience increased. Operative complications were comparable in both groups, with an occurrence of 4.2% in the open approach and 4.9% in the laparoscopic approach. Overall, the device-related reoperation rate was higher in the laparoscopy group (4.7% vs. 2.3%), primarily as a result of intraoperative disc herniation. Conversion to open procedure in the laparoscopy group was 10%, with most cases predictable and preventable. CONCLUSIONS: The laparoscopic procedure is associated with a learning curve, but once mastered, it is effective and safe when compared with open techniques of fusion.

Adult↗

PubMed1999

Path analysis of P300 amplitude of individuals from families at high and low risk for developing alcoholism.

BACKGROUND: A substantial amount of evidence exists suggesting that P300 amplitude in childhood is a risk marker for later development of alcohol dependence. There is evidence that P300 amplitude is heritable. The goal of the present study was to determine if patterns of transmission differed in families who were either at high or low risk for developing alcohol dependence. METHODS: Auditory P300 was recorded from 536 individuals spanning three generations. The path analytic TAU model was used to investigate the familial transmission of P300 amplitude in the two independent samples of families. RESULTS: Transmission of P300 in high-risk families most likely followed a polygenic model of inheritance with significant parent-to-offspring transmission. Parent-to-offspring transmission was significantly greater in high-risk than low-risk families. Total phenotypic variance due to transmissible factors was greater in low-risk families than in high-risk families, however. A somewhat unexpected finding was the substantial correlation between mates for P300 amplitude in both high- and low-risk families. CONCLUSIONS: P300 is transmissible in families. Differences exist in the pattern of transmission for P300 in families at high and low risk for alcoholism.

Adolescent↗

PubMed1999

Dishevelled proteins lead to two signaling pathways. Regulation of LEF-1 and c-Jun N-terminal kinase in mammalian cells.

Dishevelled (Dsh/Dvl) proteins are known to mediate Wnt signaling by up-regulating beta-catenin levels and stimulating T cell factor (TCF)/LEF-1-dependent transcription. We have identified a new Dvl-mediated signaling pathway in that mouse Dvl proteins, when expressed in COS-7 cells, stimulate c-Jun-dependent transcription activity and the kinase activity of the c-Jun N-terminal kinase (JNK). The DEP domain of Dvl1 is essential for JNK activation. By contrast, all three conserved domains of Dvl, including DIX, PDZ, and DEP, are required for up-regulation of beta-catenin and for stimulation of LEF-1-mediated transcription in mammalian cells. Thus, Dvl can lead to two different signaling pathways. Furthermore, the small G proteins of Cdc42 or Rac1, which are involved in JNK activation by many stimuli, do not appear to play a major role in Dvl-mediated JNK activation, because the dominant negative mutants of Cdc42 and Rac1 could not inhibit Dvl-induced JNK activation. This suggests that Dvl may activate JNK via novel pathways.

3T3 Cells↗

PubMed1999

Perioperative cimetidine application modulates natural killer cells in patients with colorectal cancer: a randomized clinical study.

Thirty-eight colorectal cancer patients were randomly assigned to treatment group, which took cimetidine in the perioperative period, and control group to which no drug was given. Twenty healthy volunteers served as normal controls. NK cells were measured by immunocytochemical technique. The results showed that NK percentages before treatment in both groups of patients were significantly lower than those in normal controls (P < 0.05). NK cell percentages at admission, before operation, on the 2nd and the 10th postoperative days were 14.84 +/- 4.41, 15.74 +/- 3.75, 17.21 +/- 3.69, 21.05 +/- 4.54, respectively, for the treatment group, and 15.00 +/- 2.77, 13.05 +/- 2.46, 14.21 +/- 2.19, 15.58 +/- 1.68, respectively, for control group. The difference was statistically significant (P < 0.01), suggesting that the perioperative administration of cimetidine could help restore NK cells in colorectal cancer patients.

Cimetidine↗