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Biomedical subjects

Y Huang

Publications and source records attributed to Y Huang.

At least 955 records · Page 53Linked to original sources
PubMed1995

Cholesterol efflux, cholesterol esterification, and cholesteryl ester transfer by LpA-I and LpA-I/A-II in native plasma.

HDLs encompass structurally heterogeneous particles that fulfill specific functions in reverse cholesterol transport. Two-dimensional nondenaturing polyacrylamide gradient gel electrophoresis (2D-PAGGE) of normal plasma and subsequent immunoblotting with anti-apolipoprotein (apo) A-I antibodies differentiates an abundant particle with electrophoretic alpha-mobility and less abundant particles with electrophoretic pre-beta-mobility (pre beta 1-LpA-I, pre beta 2-LpA-I, pre beta 3-LpA-I). Immunodetection with anti-apoA-II antibodies identifies a single particle with alpha-mobility. To differentiate alpha-migrating HDL without apo A-II (alpha-LpA-I) from those with apoA-II (alpha-LpA-I/A-II), we combined 2D-PAGGE with immunoadsorption of apoA-II. Incubation of plasma with [3H]cholesterol-labeled fibroblasts in combination with immunosubtracting 2D-PAGGE allowed us to analyze the role of alpha-LpA-I and alpha-LpA-I/A-II in the uptake and esterification of cell-derived cholesterol in native plasma. Depending on the duration of incubations with cells, alpha-LpA-I took up two to four times more [3H]cholesterol than alpha-LpA-I/A-II. Irrespective of the duration of incubation, two to three times more [3H]cholesteryl esters accumulated in alpha-LpA-I than in alpha-LpA-I/A-II. Subsequent incubations in the presence of an inhibitor of lecithin:cholesterol acyltransferase led to preferential accumulation of [3H]cholesteryl esters in alpha-LpA-I/A-II. In conclusion, our data indicate that alpha-LpA-I is more effective than alpha-LpA-I/A-II in both uptake and esterification of cell-derived cholesterol. Moreover, alpha-LpA-I/A-II appears to accumulate cholesteryl esters, at least partially, from alpha-LpA-I.

Apolipoprotein A-I↗
PubMed1995

Effects of the apolipoprotein E polymorphism on uptake and transfer of cell-derived cholesterol in plasma.

The reverse cholesterol transport is initiated by the uptake of cholesterol into minor subfractions of high density lipoproteins (HDL) which contain either apolipoprotein (apo) A-I or apoE as their only apolipoproteins. From these initial acceptors, which are termed prebeta1-LpA-I and gamma-LpE, respectively, cell-derived cholesterol is transferred to LDL via the bulk of HDL termed alpha-LpA-I. In this study we analyzed the effect in plasma of the genetically determined apoE polymorphism on the formation of gamma-LpE, uptake and transfer of cell-derived cholesterol to LDL. Gamma-LpE was immunologically detectable in plasmas of individuals carrying at least one apoE3-allele but not in apoE3-free plasmas. During one minute incubation with [3H]cholesterol-labeled fibroblasts, gamma-LpE of plasmas from apoE3/3 subjects accumulated 7 and 13-fold more radioactivity than the respective fractions in plasmas from apoE2/2- and apoE4/4-subjects, respectively. Totally, 30% less [3H]cholesterol was released into plasmas of apoE2/2 and apoE4/4-individuals as compared with plasmas of apoE3/3-subjects. Moreover, plasmas of apoE3/3 individuals accumulated 50% and 65% more cell-derived [3H]cholesterol in alpha-LpA-I2 than plasmas of apoE4/4 and apoE2/2-subjects, respectively. These results indicate that the apoE-polymorphism is an important determinant of the uptake and transfer of cell-derived cholesterol in plasma.

Apolipoprotein A-I↗
PubMed1995

Methods for estimation of subsample time delays of digitized echo signals.

Time delay estimation (TDE) is commonly performed in practice by crosscorrelation of digitized echo signals. Since time delays are generally not integral multiples of the sampling period, the location of the largest sample of the crosscorrelation function (ccf) is an inexact estimator of the location of the peak. Therefore, one must interpolate between the samples of the ccf to improve the estimation precision. Using theory and simulations, we review and compare the performance of several methods for interpolation of the ccf. The maximum likelihood approach to interpolation is the application of a reconstruction filter to the discrete ccf. However, this method can only be approximated in practice and can be computationally intensive. For these reasons, a simple method is widely used that involves fitting a parabola (or other curve) to samples of the ccf in the neighborhood of its peak. We describe and compare two curve-fitting methods: parabolic and cosine interpolation. Curve-fitting interpolation can yield biased time-delay estimates, which may preclude the use of these methods in some applications. The artifactual effect of these bias errors on elasticity imaging by elastography is discussed. We demonstrate that reconstructive interpolation is unbiased. An iterative implementation of the reconstruction procedure is proposed that can reduce the computation time significantly.

Computer Simulation↗
PubMed1995

Relationship of acute gastrointestinal toxicity and the volume of irradiated small bowel in patients receiving combined modality therapy for rectal cancer.

PURPOSE: To determine the relationship between acute gastrointestinal (GI) toxicity during the combined modality segment and the volume of small bowel in the pelvic radiation field in patients who receive either preoperative or postoperative therapy for rectal cancer. PATIENTS AND METHODS: The patient population was derived from four consecutive phase I dose-escalation trials. Combined modality therapy included fluorouracil (5-FU), leucovorin ([LV] bolus daily x 5, days 1 and 29), and pelvic radiation. RESULTS: Twenty patients who received postoperative therapy had a larger volume of small bowel in the pelvic radiation field as compared with 60 who received preoperative therapy (462 +/- 129 v 212 +/- 44 cm3, P = .002). The most significant relationship between acute GI toxicity and volume of small bowel was seen in 12 patients who were treated on the preoperative sequential low-dose LV trial, all of whom received the maximum-tolerated dose (MTD) of 5-FU. The volume of small bowel in patients who experienced grade 3+ toxicity was 731 +/- 274 cm3, as compared with 145 +/- 58 in those who experienced grade 0 to 2 toxicity (P = .005). Likewise, logistic regression analysis showed that 26 patients who received the MTD of 5-FU had the most significant association between GI toxicity and volume of small bowel (P = .036). CONCLUSION: Our data suggest that the volume of small bowel in the pelvic radiation field may be dose-limiting in the delivery of high-dose 5-FU when combined with LV and radiation therapy.

Adenocarcinoma↗
PubMed1995

Physiology of fatigue in amyotrophic lateral sclerosis.

We investigated the mechanisms of muscle fatigue in ALS. In the muscles of ALS patients and healthy control subjects, we examined (1) fatigue using measurements of muscle force, (2) energy metabolism using phosphorus-31 magnetic resonance spectroscopy, and (3) activation using neurophysiologic measures and MRI. During 25 minutes of intermittent isometric exercise of the tibialis anterior muscle, both maximum voluntary and tetanic force declined more in patients than in controls, indicating greater fatigability in ALS. There was a similar decline of voluntary and tetanic force, suggesting that much of the fatigue was not central. Evoked compound muscle action potential amplitudes were preserved during exercise in both groups, indicating no failure of neuromuscular transmission; this result suggests that the source of fatigue was not at the neuromuscular junction or within the muscle membrane. In spite of greater fatigability, changes during exercise in energy metabolites and proton signal intensity tended to be less in ALS patients compared with controls, suggesting impaired muscular activation. We conclude that the greater muscle fatigue in ALS patients results from activation impairment, due in part to alterations distal to the muscle membrane.

Action Potentials↗
PubMed1995

Determination of a depolymerized holothurian glycosaminoglycan in plasma after intravenous administration by postcolumn HPLC.

Depolymerized holothurian glycosaminoglycan (DHG) produced artificially from sea cucumber has an anticoagulant and antithrombotic activity. In the present study, we attempted to determine the plasma level of DHG using a chemical procedure. A general method for determination of chondroitin sulfates by forming unsaturated disaccharides with chondroitinase digestion was difficult to apply to DHG, because it was resistant to any chondroitinase digestion. We therefore developed a highly sensitive postcolumn HPLC method for determination of intact DHG. DHG was applied to Asahipak NH2P-50, an amino-bonded column, eluted by alkaline solution and then detected with arginine under a strong alkaline condition as a postcolumn reagent. The limit of detection for DHG was 10 ng. The present method was applicable to the determination of DHG in plasma after intravenous administration.

Animals↗
PubMed1995

pIXY321 protects against Ara-C or taxol-induced apoptosis and loss of clonogenic survival of normal human bone marrow progenitor cells.

By suppressing apoptosis, hemopoietic growth factors (HGFs) promote the survival of CD34+, HLA-DR+ marrow cells that are enriched for hemopoietic progenitor cells (HPC). In the present studies, we have examined the effects of pIXY321, a genetically engineered fusion protein of GM-CSF and IL-3 (GM-CSF/IL-3), on high-dose Ara-C (HIDAC) and taxol-induced apoptosis and survival of a multilineage HPC, the CFU-GEMM. Exposure to 1.0 mumol/l taxol for 24 h or HIDAC > or = 10 mumol/l for 4 h induced internucleosomal DNA fragmentation and the morphologic features of apoptosis in CD34+, HLA-DR+ cells. These treatments were associated with > or = 50% inhibition of the assayable CFU-GEMM colony numbers. Incubation in serum-free medium (SFM) alone for 24 h also induced apoptosis of CD34+, HLA-DR+ cells, which was associated with reduced intracellular levels of the bcl-2 gene product p26BCL-2. Co-treatment with pIXY321 (10 ng/ml) inhibited apoptosis of CD34+, HLA-DR+ cells incubated in SFM, without significantly increasing the intracellular p26BCL-2 levels. Furthermore, co-treatment with pIXY321 significantly reduced taxol- and Ara-C-induced apoptosis and promoted the survival of CFU-GEMM (P < 0.05). Taxol and Ara-C mediated apoptosis of CD34+, HLA-DR+ cells, and its inhibition by pIXY321, was not accompanied by any significant alteration in the intracellular p26BCL-2 levels. By demonstrating that co-treatment with pIXY321 confers significant protection against apoptosis of CD34+, HLA-DR+ cells as well as promotes survival of normal HPC exposed to clinically relevant schedules and concentrations of taxol of Ara-C, these results support the design of chemotherapy regimens incorporating pIXY321 plus taxol and/or high-dose Ara-C for solid tumors and/or acute leukemias. It is hoped that the use of such a cytokine might maintain normal HPC numbers following chemotherapy, therefore avoiding prolonged suppression.

Antigens, CD34↗
PubMed1995

Localization of alpha 2-adrenergic receptor subtypes in the anterior segment of the human eye with selective antibodies.

PURPOSE: To develop antibodies that selectively recognize each of the alpha 2-adrenergic receptor (AR) subtypes and to determine the expression and localization of these subtypes in the anterior segment of the human eye. METHODS: Recent studies have shown that there are three subtypes of the alpha 2-ARs, termed alpha 2-C10 (alpha 2A), alpha 2-C2 (alpha 2B), and alpha 2-C4 (alpha 2C). Polymerase chain reaction was used to amplify portions of these receptors fused (in-frame) to a cDNA encoding glutathione-S-transferase (GST). The expressed fusion proteins were used to immunize chickens, and antibodies were generated. Immunofluorescence microscopy was used to localize the alpha 2-AR subtypes in sections of human and rabbit ciliary body. Polymerase chain reaction and dot blot hybridization were used to determine which subtypes were present in RNA from primary cultures of human nonpigmented epithelium (NPE) and rabbit iris-ciliary body (ICB). RESULTS: Immunofluorescence microscopy of COS cells transfected with the alpha 2-AR subtypes showed that the antibodies raised against the GST-receptor fusion proteins specifically recognized their respective receptor subtypes. In the human ciliary body, alpha 2 B and alpha 2C immunoreactivity were present in the NPE and ciliary muscle. In the rabbit ciliary body, alpha 2A immunoreactivity also was present. Polymerase chain reaction and dot blot hybridization indicated that RNA encoding the alpha 2B and alpha 2C subtypes was present in human NPE and that RNA encoding all three subtypes was present in the rabbit ICB. CONCLUSIONS: Multiple alpha 2-adrenergic subtypes are expressed in the ciliary body. In the human, alpha 2B and alpha 2C predominate, whereas all three are present in the rabbit. This could be important with respect to animal models of glaucoma and to the development of drugs for lowering intraocular pressure.

Animals↗
PubMed1995

[Epidemiological studies on endemic fluorosis and arsenism in Xinjiang].

Epidemiological and clinical studies on the water of 102 wells containing high-level fluoride and arsenic and a population of 50,760 drinking the water in Kuitun Area, Xinjiang were conducted. Results indicated fluoride and arsenic contents in the well water were associated with geochemical environment, and drinking the water containing high-level fluoride and arsenic for a long-term was the cause of fluorosis and arsenism. Also, diagnostic criteria and major clinical manifestations for fluorosis and arsenism were put forward in the paper. Relationship between fluoride and arsenic contents in the well water and prevalence of fluorosis and arsenism in local residents was analyzed. It suggested fluorosis and arsenism was a systematic disorder and further studies on its potential hazard were merited.

Adolescent↗
PubMed1995

[Morphologic characteristic of substance P immunoreactivity in facial nerve of normal cats].

This paper presents the morphologic charactistic of substance P immunoreactivity (SP-IR) in the facial nerve and geniculate ganglion of normal cats by using immunohistochemical technique and immunoelectronic microscopy. SP-IR positive cells are more in geniculate ganglion than the other parts of the facial nerve. These cells are black. The sizes of their somata are different, and the shapes are round, elliptic or irregular. The somata are connected with each other by their central and peripheral synapses in the shapes of spider's web or root of a tree. Among the cells the bipolar and pseudounipolar cells are also found. SP-IR positive fibers curve and some of them have obvious expansive bodies, which are beaded, different in diameter. Under electronic microscope SP-IR positive cells show thicker electronic density than the others, and SP-IR positive products with thick electronic density are found in the nuclei, nucleomembranes, outer membranes of mitochndria and plasma. The nerve fibers are myelinated and the myelin sheath is concentric, and in the axoplasms there are nervous microfilament and a bit of mitochndria.

Animals↗
PubMed1995

Experimental study on the model of coronary artery thrombosis in dog.

We have developed a model of coronary artery thrombosis in dog by using the method stimulating coronary adventitia with direct current. The results have shown that the thrombi are similar to human artery thrombi in composition and the model of coronary artery thrombosis is satisfactory and the time of forming thrombosis is shorter than that by other methods.

Animals↗
PubMed1995

Quantitative evaluation of Al maltolate-induced neurodegeneration with subsequent Al removal by desferrioxamine treatment.

The intracisternal administration of aluminum maltolate to New Zealand white rabbits produces a reproducible neurofibrillary degeneration which is significantly reversed by desferrioxamine treatment. Quantitative analysis of brain and spinal cord tissue demonstrates that the aluminum deposition is higher close to the injection site than at locations further removed from the point of administration. Most importantly, treatment with desferrioxamine removes most of the aluminum from the brain and spinal cord, even from the sites of highest concentration. The ability to manipulate this system in the formation and degradation of NFD and in removal of aluminum may shed light on mechanisms of NFD formation and have implications for therapeutic advances in the treatment of certain human neurodegenerative diseases.

Aluminum↗
PubMed1995

The electrophysiologic effects of endothelin. A patch clamp study in guinea pig ventricular myocytes.

To study the electrophysiologic effects of endothelin-1 (ET-1), we used patch clamp and glass microelectrode techniques to investigate the effects of ET-1 on cardiac L-Ica, Ik and Ik2 in guinea pig ventricular myocytes. The prolongation of APD50 was induced and EADs was triggered by 50 nM ET-1 perfusion. L-Ica and Ik were enhanced by various ET-1 concentration from 1 to 50 nM with dose-dependence. Their steady-state activations of L-Ica and Ik shifted left with ET-1 concentration increments. ET-1 elicited a kind of GTP-dependent inward rectifier K+ current having a mean conductance of 82.36 +/- 1.27 pS. The open time and close time (both interburst intervals and burst durations) abbreviated with ET-1 concentration increase. The results suggested that EADs -ET evoked was ascribed to the prolongation on the plateau level, which resulted from L-Ica enhancement. The ET- evoked inward rectifier K+ current should be further studied.

Action Potentials↗
PubMed1995

[Analysis of hepatitis B virus X antigen expression in chronic hepatitis B and cirrhosis].

It has been shown that hepatitis B virus (HBV) X antigen (HBxAg) functioned as a transactivating element which can act on the enhancer of HBV in an in vitro system and elevate the transcriptional level of HBV. In this study we investigate the relationship between HBxAg expression and HBV replication in patients with chronic hepatitis B and cirrhosis. Rabbit IgG against recombinant HBxAg which was synthesized in E. coli were prepared and used for the detection of HBxAg. HBV DNA was amplified by polymerase chain reaction technique by using primers from HBx gene sequence. Liver tissue samples and sera from the patients were examined immunohistochemically for HBxAg and serologically for HBxAg/anti-HBx respectively. We focused on its expression in these samples in comparison with markers of HBV replication. It was found that in liver HBxAg was present in 72.7% of the patients with chronic active hapatitis (CAH) and 92.6% of those with cirrhosis, while the positivity rate of HBcAg in cirrhosis patients was only 47.8%. In the sera of the patients with CAH, chronic persistant hepatitis and cirrhosis HBxAg was present in 44.4%, 66.6% and 33.3% respectively. It was similar to that observed with HBeAg. Moreover in these HBxAg positive sera HBV DNA can also be detected. It was shown that higher rate of positivity of HBxAg was found in patients with replicative markers (serum HBeAg, serum HBV DNA or liver tissue HBcAg positive). Our results indicate that expression of HBxAg is closely correlated with HBV replication and HBxAg may be an important marker in chronic HBV infection.

Animals↗
PubMed1995

[Study of operative indication and timing for acute necrotizing pancreatitis].

65 patients of acute necrotizing pancreatitis were reported. 36 patients underwent operation with a mortality of 27.8%. However the mortality in 29 patients treated nonoperatively, the mortality was 3.4% because of their less critical condition. In operation group 7 out of 17 patients died (41.2%) with positive results in bacterial smear or culture while all 5 patients with negative results survived. The time from onset to admission in the survivor and the dead was 33 hours and 85 hours respectively. The time from onset to operation was 41 hours in the survivor while 138.8 hours in the dead. So the prognosis related closely to early intensive care therapy and if indicated, surgical intervention timely. The indication and timing of operation were discussed.

Acute Disease↗
PubMed1995

[Clinical behavior and cytobiological activity of desmoid tumor].

Desmoid tumor, characterized by aggressive growth and frequent recurrence without metastasis after excision, remains to be a poorly understood neoplasm. In seventeen patients with desmoid tumor of the extremities, the relationship between the cytobiological activity and prognosis of desmoid tumor was studied by reviewing clinical material, histologic examination, statistical analysis of Ag-NORs, and morphometry of tumor cell nuclei in comparison with those of fibrosarcoma and soft tissue fibroma. The results showed that the cells of desmoid tumor were highly proliferative with their biological activity bearing resemblance to fibrosarcoma. Thus we have good grounds for grouping desmoid tumors as of low grade malignancy. We believe that initial surgical resection with a wide margin is the key for good prognosis because a lower recurrence rate will result.

Adolescent↗
PubMed1995

[Application of gasless laparoscopic device in laparoscopic surgery].

The aim of this study was to evaluate the gasless laparoscopic device (GLD) in laparoscopic surgery. GLD, independently designed and manufactured by ourselves in 1993, incorporates a manipulator and laparoscopic abdominal retractor. From August to October 1993, we conducted an experimental study on gasless laparoscopic cholecysto-duodenostomy in 5 dogs. Four of them were completely successful and one was converted to open surgery due to gallbladder rupture. The result showed that GLD could maintain good exposure in laparoscopic surgery, laparoscopic suturing and knotting could become easier and operative cost could be reduced with conventional instruments. We also developed an intracorporeal "Chinese Knotting" and a self-designed push tube for extracorporeal knot tying. During April and August 1994, we successfully applied our modified GLD in gasless laparoscopic cholecystectomy, inguinal herniorrhaphy laparoscopic-assisted sigmoidectomy, abdomino-perineal resection of rectal carcinoma.

Adenocarcinoma↗