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Biomedical subjects

X Hong

Publications and source records attributed to X Hong.

At least 19 recordsLinked to original sources
PubMed2006

Thoracic epidural analgesia facilitates the restoration of bowel function and dietary intake in patients undergoing laparoscopic colon resection using a traditional, nonaccelerated, perioperative care program.

BACKGROUND: This randomized trial compared thoracic epidural analgesia with patient-controlled analgesia (PCA) using morphine for laparoscopic colectomy in a traditional, nonaccelerated, perioperative care program. METHODS: In the study, 50 patients scheduled for elective laparoscopic colon resection were randomized to either PCA morphine (n = 25) or thoracic epidural analgesia with bupivacaine and fentanyl (n = 25). Both groups received general anesthesia and multimodal pain relief, which included naproxen and acetaminophen for as long as 4 postoperative days. Time until passage of gas and bowel movements, dietary intake, postoperative quality of analgesia, readiness for discharge, and length of hospital stay were recorded. RESULTS: Recovery of postoperative ileus occurred sooner in the epidural group (p < 0.005) by an average 1 to 2 days, and resumption of full diet was achieved earlier (p < 0.05). Intensity of pain during the first 2 postoperative days was significantly lower at rest, with coughing, and with walking in the epidural group (p < 0.005). Readiness for discharge and hospital length of stay (5 days) were otherwise similar in the two groups. CONCLUSIONS: When a traditional perioperative care program is used for laparoscopic colectomy, thoracic epidural analgesia is superior to PCA in accelerating the return of bowel function and dietary intake, while providing better pain relief.

Aged↗
PubMed2006

Arsenic trioxide reduces the invasive and metastatic properties of nasopharyngeal carcinoma cells in vitro.

Nasopharyngeal carcinoma (NPC) is notorious for the metastases, which are in close association with Epstein-Barr virus-encoded latent membrane protein 1 (LMP1). Arsenic trioxide (As2O3) has been shown to induce apoptosis and differentiation in NPC xenografts. Then, can it repress the cancer cells' metastasis potential? To elucidate this issue, the present study was performed. LMP1-negative cell line HNE1 and LMP1-positive cell line HNE1-LMP1 were used as in vitro model. Cells (1 x 10(5)/mL) were cultured with or without 3 microM As2O3 for 48 h. Then the survival cells were collected to investigate their potential of colony formation, attachment, invasion, and migration. Both confocal immunofluorescence staining and Western blot were used to detect the changes of LMP1 expression. The changes of MMP-9 were examined by RT-PCR assay and Western blot. The results were as follow: i) the colony formation inhibition rate (75.41 +/- 3.9% in HNE1-LMP1 cells vs 37.89 +/- 4.9% in HNE1 cells), the rate of attachment (HNE1-LMP1 vs HNE1: 56.40 +/- 3.5 vs 65.87 +/- 5.9%), the invasion inhibitory rate (HNE1-LMP1 vs HNE1: 56.50 +/- 3.7 and 27.91 +/- 2.1%), and the migration inhibitory rate (HNE1-LMP1 vs HNE1: 48.70 +/- 3.9 vs 29.19 +/- 6.27%) were all significantly different between the two cell lines (P < 0.01). ii) LMP1 was down-regulated in As2O3-treated HNE1-LMP1 cells. iii) The reduction of MMP-9 was found in As2O3-treated groups, more evident in HNE1-LMP1 cells. Thus, we conclude that As2O3 can reduce metastasis potential of NPC cells, involving inhibition of MMP-9 expression. LMP1 were also reduced in this process and seemed to enhance anti-metastasis activity of As2O3.

Antineoplastic Agents↗
PubMed2006

Dichloroacetate causes toxic neuropathy in MELAS: a randomized, controlled clinical trial.

OBJECTIVE: To evaluate the efficacy of dichloroacetate (DCA) in the treatment of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). BACKGROUND: High levels of ventricular lactate, the brain spectroscopic signature of MELAS, correlate with more severe neurologic impairment. The authors hypothesized that chronic cerebral lactic acidosis exacerbates neuronal injury in MELAS and therefore, investigated DCA, a potent lactate-lowering agent, as potential treatment for MELAS. METHODS: The authors conducted a double-blind, placebo-controlled, randomized, 3-year cross-over trial of DCA (25 mg/kg/day) in 30 patients (aged 10 to 60 years) with MELAS and the A3243G mutation. Primary outcome measure was a Global Assessment of Treatment Efficacy (GATE) score based on a health-related event inventory, and on neurologic, neuropsychological, and daily living functioning. Biologic outcome measures included venous, CSF, and 1H MRSI-estimated brain lactate. Blood tests and nerve conduction studies were performed to monitor safety. RESULTS: During the initial 24-month treatment period, 15 of 15 patients randomized to DCA were taken off study medication, compared to 4 of 15 patients randomized to placebo. Study medication was discontinued in 17 of 19 patients because of onset or worsening of peripheral neuropathy. The clinical trial was terminated early because of peripheral nerve toxicity. The mean GATE score was not significantly different between treatment arms. CONCLUSION: DCA at 25 mg/kg/day is associated with peripheral nerve toxicity resulting in a high rate of medication discontinuation and early study termination. Under these experimental conditions, the authors were unable to detect any beneficial effect. The findings show that DCA-associated neuropathy overshadows the assessment of any potential benefit in MELAS.

Action Potentials↗
PubMed2006

Kernel classifier construction using orthogonal forward selection and boosting with Fisher ratio class separability measure.

A greedy technique is proposed to construct parsimonious kernel classifiers using the orthogonal forward selection method and boosting based on Fisher ratio for class separability measure. Unlike most kernel classification methods, which restrict kernel means to the training input data and use a fixed common variance for all the kernel terms, the proposed technique can tune both the mean vector and diagonal covariance matrix of individual kernel by incrementally maximizing Fisher ratio for class separability measure. An efficient weighted optimization method is developed based on boosting to append kernels one by one in an orthogonal forward selection procedure. Experimental results obtained using this construction technique demonstrate that it offers a viable alternative to the existing state-of-the-art kernel modeling methods for constructing sparse Gaussian radial basis function network classifiers that generalize well.

Algorithms↗
PubMed2004

Automatic kernel regression modelling using combined leave-one-out test score and regularised orthogonal least squares.

This paper introduces an automatic robust nonlinear identification algorithm using the leave-one-out test score also known as the PRESS (Predicted REsidual Sums of Squares) statistic and regularised orthogonal least squares. The proposed algorithm aims to achieve maximised model robustness via two effective and complementary approaches, parameter regularisation via ridge regression and model optimal generalisation structure selection. The major contributions are to derive the PRESS error in a regularised orthogonal weight model, develop an efficient recursive computation formula for PRESS errors in the regularised orthogonal least squares forward regression framework and hence construct a model with a good generalisation property. Based on the properties of the PRESS statistic the proposed algorithm can achieve a fully automated model construction procedure without resort to any other validation data set for model evaluation.

Algorithms↗
PubMed2001

Graft survival in a rhesus renal transplant model after immunotoxin-mediated T-cell depletion is enhanced by mycophenolate and steroids.

BACKGROUND: Anti-CD3 immunotoxin (IT), a T-cell-depleting agent, prolongs survival of renal allografts in a rhesus monkey model without the need for long-term immunosuppression. In this study we sought to further prolong allograft survival by giving short-term conventional immunosuppression simultaneous with IT administration. METHODS: MHC class II mismatched, juvenile rhesus monkeys were paired as donor and recipient for renal transplantation. Recipients received two to three daily doses of IT starting on the day of transplantation. Additional immunosuppression was given for no more than 60 days. Graft function was monitored by serum creatinine and renal biopsies. Flow cytometry was used to monitor T-cell recovery. RESULTS: Graft survival time (GST) in animals receiving IT was prolonged compared with controls with 50% of IT-treated monkeys surviving >100 days. Animals treated with IT plus mycophenolate mofetil (MMF) and steroids had significantly enhanced GST (mean GST, 305 days) compared with those treated with IT alone (mean GST, 94 days). In contrast, addition of cyclosporine or 40-O-[2-Hydroxyethyl]rapamycin did not significantly increase graft survival time. A comparison among animals from all treatment groups with short (<100 days) and long (>100 days) GST demonstrated that those with the shorter GST had a higher blood T-cell count 2 weeks after transplantation. Full recovery of CD4+ T cells required longer than 6 months. CONCLUSIONS: A combination with MMF and steroids given for 4 days after renal allograft transplantation significantly increases GST in IT-treated monkeys. We hypothesize that MMF and steroids suppress the initial T-cell activation mediated by IT.

Animals↗
PubMed2001

CSN3 interacts with IKKgamma and inhibits TNF- but not IL-1-induced NF-kappaB activation.

The transcription factor nuclear factor kappaB (NF-kappaB) plays a pivotal role in immune and inflammatory responses. Activation of NF-kappaB requires the activity of IKK, a kinase complex that contains two catalytic subunits, IKKalpha and IKKbeta, and a regulatory subunit IKKgamma. To understand how IKK activity is regulated, we searched for IKKgamma-interacting proteins by the yeast two-hybrid system. These screenings identified CSN3, a component of the COP9 signalsome, as a protein specifically interacting with IKKgamma. Overexpression of CSN3 inhibits NF-kappaB activation triggered by tumor necrosis factor (TNF), but not interleukin-1 (IL-1). Moreover, overexpression of CSN3 also inhibits NF-kappaB activation triggered by proteins involved in TNF signaling, including TNF-R1, TRAF2, RIP, and NIK, but not by TRAF6, a protein involved in IL-1 signaling. These data suggest that CSN3 is a specific negative regulator of TNF- but not IL-1-induced NF-kappaB activation pathways.

Blotting, Western↗
PubMed2001

EXAFS measurements for liquid Ge-Si alloys.

EXAFS measurements around the Ge-K edge have been carried out for liquid Ge-Si alloys for the first time to investigate the local structure around a Ge atom. To perform the EXAFS measurements for the liquid alloys with high melting temperatures, a new sapphire cell have been developed. The measurements were carried out for the liquid alloys from 10% to 60% of Si and the crystalline ones from 10% to 70% of Si as a reference. EXAFS oscillations, x(k), are observed even at 1480 degrees C for liquid Ge(0.4)Si(0.6). The position of the first peak in the radial distribution function obtained from Fourier transform of x(k) is shifted towards smaller distance for liquid and crystalline alloys with increasing Si concentration. The results of a curve-fit analysis in a harmonic approximation show that Ge-Ge and Ge-Si bonds in the liquid alloys become long with increasing Si concentration while those become slightly short in the crystaline ones.

Journal Article↗
PubMed2001

Linkage of body mass index to chromosome 20 in Utah pedigrees.

Several linkage studies have hinted at the existence of an obesity predisposition locus on chromosome 20, but none of these studies has produced conclusive results. Therefore, we analyzed 48 genetic markers on chromosome 20 for linkage to severe obesity (BMI> or =35) in 103 extended Utah pedigrees (1,711 individuals), all of which had strong aggregation of severe obesity. A simple dominant model produced a maximum multipoint heterogeneity LOD score of 3.5 at D20S438 (55.1 cM). Two additional analyses were performed. First, a one-gene, two-mutation model (with one dominant mutation and one recessive mutation) increased the LOD score to 4.2. Second, a two-locus model (with one locus dominant and one recessive) generated a multipoint LOD score of 4.9. We conclude that one or more severe obesity predisposing genes lie within an interval of approx. 10 cM on chromosome 20. This study generated significant LOD scores which confirm suggestive linkage reports from previous studies. In addition, our analyses suggest that the predisposing gene(s) is localized very near the chromosome 20 centromere.

Body Mass Index↗
PubMed2001

Role and regulation of activation of caspases in cisplatin-induced injury to renal tubular epithelial cells.

BACKGROUND: Cellular and molecular mechanisms responsible for cisplatin-induced nephrotoxicity to renal tubular epithelial cells are not well understood. Although caspases play a critical role in the execution of the cell death pathway, their specific role in toxic injury to renal tubular epithelial cells has not been elucidated previously. METHODS: The role of caspases in cisplatin-induced injury was determined using caspase inhibitors and p35 transfected LLC-PK1 cells. The Akt/PKB phosphorylation pathway was studied for the regulation of caspase activation in these cells. RESULTS: The activation of initiator caspases-8, -9 and -2, and executioner caspase-3 began after eight hours of cisplatin treatment, thereafter markedly increased in a time (8 to 24 hours) and dose-dependent manner (0 to 200 micromol/L). Proinflammatory caspase-1 did not show cisplatin-induced activation. Inhibition of caspase-3 by over expressing cowpox virus p35 protein or alternatively by the peptide inhibitor DEVD-CHO provided marked protection against cell death and partial protection against DNA damage. We then examined the role of the Akt/PKB phosphorylation pathway in regulation of cisplatin-induced caspase activation. There was a marked induction of Akt/PKB phosphorylation in a time (0 to 8 hours) and dose-dependent (0 to 200 micromol/L) manner during the course of cisplatin injury. Cisplatin-induced Akt/PKB activation was associated with Bad phosphorylation, suggesting induction of a cell survival signal mediated by the Bcl-2 family member, Bad. Wortmannin or LY294002, two structurally dissimilar inhibitors of phosphatidylinositol 3'-kinase (PI-3 kinase), abolished both cisplatin-induced Akt phosphorylation and Bad phosphorylation, and promoted cisplatin-induced early and accelerated activation of caspase-3 and caspase-9, but not of caspase-8 and caspase-1, indicating that inhibition of the Akt/PKB phosphorylation pathway enhances the mitochondrial-dependent activation of caspases. The impact of enhanced activation of caspases by wortmannin or LY294002 was reflected on accelerated cisplatin-induced cell death. CONCLUSIONS: These studies demonstrate differential activation and role of caspases in cisplatin injury, and provide the first evidence of cisplatin-induced induction of the Akt/PKB phosphorylation pathway, inhibition of which enhances activation of caspase-3 and caspase-9.

Animals↗
PubMed2001

Use of a Shack-Hartmann aberrometer to assess the optical outcome of corneal transplantation in a keratoconic eye.

We report the optical outcome of corneal transplantation treatment on a keratoconic eye as measured with a Shack-Hartmann aberrometer, and we compare the results with the recovery of visual acuity after surgery. Before surgery, the naked keratoconic eye exhibited extremely large aberrations that could not be measured unless the patient wore a rigid gas-permeable contact lens. With the lens, the computed point-spread function of the eye was large and multimodal, and simulated retinal images confirmed the patient's subjective report of multiple, overlapping images. After full recovery from surgery, aberrations of the corrected eye were much smaller compared with the presurgical eye, which implied a more compact point-spread function and clearer retinal images. These optical changes were mirrored by an improvement in uncorrected visual acuity from 1.3 logarithm of the minimum angle of resolution (logMAR) before surgery to 0 logMAR with spectacle correction after full recovery. We conclude that the Shack-Hartmann aberrometer provides an objective, quantitative assessment of the optical outcome of penetrating keratoplasty that allows the clinician to measure retinal image quality objectively and to accurately simulate the complex visual distortions associated with keratoconus.

Cornea↗
PubMed2001

On-eye evaluation of optical performance of rigid and soft contact lenses.

A Shack-Hartmann aberrometer was used to assess the optical performances of eyes corrected with rigid or soft contact lenses compared with spectacles. Metrics of optical quality derived from the measured wave aberrations were consistent with the subjective rating of visual clarity by subjects. Optical aberration analysis illustrated the differences in aberration structures of eyes wearing different optical corrections. For our subjects, correction with a rigid gas-permeable lens yielded significantly better optical quality than did the soft contact lens or spectacle lens. This was due to a reduction in the eye's asymmetric (odd-order) aberrations and a reduction in the amount of the eye's positive spherical aberration. These observations can be explained by theoretical calculations of the aberrations of the eye plus lens optical system. We conclude that aberrometry provides a better understanding of the optical effects of contact lenses in situ and could be useful for optimizing future designs of contact lenses.

Contact Lenses, Hydrophilic↗
PubMed2001

[Design of multi-channel EEG collection system for stereoscopic VEP and study of the VEP evoked by binocular disparity].

A multi-channel EEG collection system has been constructed for visual evoked potentials (VEP) studies, using IBM compatible PC and clinical EEG amplifier. The collection system not only is suitable for investigative and clinical use, but also works perfectly in the EEG collection and signal processing of stereoscopic VEP. The characters of the depth related VEP evoked by binocular disparity were identified after analysing and comparing the VEP superposition results. The partial results of the VEP extraction are in accord with the previous studies. The system serves as a helpful tool in studies of stereoscopic cognition and brain function.

Adult↗
PubMed2001

Nitric oxide in vPAG mediates the depressor response to acupuncture in stress-induced hypertensive rats.

The hypertensive rat model was made by chronic stress of electric foot-shocks and noises. On such hypertensive rats, when anesthetized with urethane and chloralose, the electroacupuncture (EA) to bilateral "Zusanli (st.36)" acupoints for 20 min, could result in a depressor (including both systolic and diastolic pressure) and bradycardiac response as well as an attenuation in the maximum of left ventricular pressure, end diastolic pressure and +/-dp/dt. In power spectrum analysis of heart rate variability aspect, EA could increase all total variance, very low frequency component, low frequency component and the ratio of low frequency component and high frequency component. When EA with microinjection of N(omega) - Nitro- L-Arginine , a blocker of the formation of nitric oxide, into the ventral periaqueductal gray matter (vPAG), the above effects of EA were abolished or reduced significantly. The results suggest that the depressor effect of EA on stress-induced hypertensive rats might be mediated by nitric oxide in the vPAG due to activation of sympathetic inhibitory system and by attenuated cardiac activities.

Acupuncture Points↗
PubMed2001

[A case-control study of endogenous estrogen and risk of Alzheimer's disease].

OBJECTIVE: To investigate the risk of Alzheimer's disease (AD) associated with endogenous estrogen. METHODS: A population based, m: n matched case-control study was conducted, including 115 female AD patients identified from sample population aged 55 years or older as cases and 1,041 non-cognitive impairment individuals from same population matched for age and sex as controls. RESULTS: Age at natural menopause had significant effect on AD using multivariate analysis. The odds ratio (OR) for AD was 0.672 for individuals whose age at natural menopause were between 47 to 50 years old, compared with individuals whose age at menopause were less than 47 years old. The OR was 0.452 for individuals whose age at menopause were more than 50 years old comparing with individuals whose age at menopause were less than 47 years old (P = 0.0207). The OR for AD increased parallel to the increase of age at menarche (adjusted OR = 1.160 for each increased year, P = 0.0342). CONCLUSION: The decrease of endogenous level in postmenopausal women might serve an etiological factor for AD.

Alzheimer Disease↗
PubMed2001

[An analysis on the forearm bone mass density of rural female and the environmental risk factors].

The distribution of distal and proximal forearm bone mass densities (BMD) with age was discribed and the environmental risk factors of rural female analyzed. A group of 1432 rural female aged 15 and over were sellected. Their demographic characteristics, living and eating habit were obtained by standardized questionnaire. The distal and proximal forearm bone mass density were measured by peripheral dual-energy X ray absorptionmetry (pDEXA). The results showed that the distal and proximal forearm BMDs were increased with age before age 25 and 30 respectively, and reached the peak value at age 30-35. The distal forearm bone density decreased significantly at age 40 while the proximal forearm BMD decreased at age 45. Bone loss rate of the two bone sites was increased significantly at age 50 and reached the peak value at age 55-60. Only the the density of proximal forearm bone, and the year of menopause was the main cause of low bone density. Body weight was the positive factor for bone density at age less than 60. Height only positively affected the proximal forearm bone of those at age 30-45. More ever, drinking tea, parity and educational status may affect distal forearm bone in certain age group while parity, educational status, occupation and marital status were possible risk factors of proximal forearm BMD. It is concluded that environmental risk factors of BMD varied with bone site and age. The prevention of low BMD must rely on subject's age and bone site. The surveillance of low bone density must put the emphasis on spony bone.

Adult↗
PubMed2000

Increased glomerular deposits of von Willebrand factor in chronic, but not acute, rejection of primate renal allografts.

BACKGROUND: In our previously described primate renal allograft model, T cell ablation leads to long-term graft survival. The role of endothelial cell alteration in chronic rejection was examined in our model. METHODS: Renal transplants were performed in rhesus monkeys using a T cell- depleting immunotoxin, FN18-CRM9. Sections from 10 rejected kidneys (5 acute and 7 chronic rejection) were examined after immunohistochemical staining for expression of endothelium-related proteins [von Willebrand factor (vWF), CD62P, and CD31], fibrinogen, and a macrophage marker (CD68). Glomerular staining for each antigen was graded on a semiquantitative scale. RESULTS: Intense staining for vWF was consistently observed in glomerular endothelium, subendothelium, and mesangium in all kidneys removed due to chronic rejection. vWF staining was weak in kidneys showing acute rejection. The difference in glomerular staining was statistically significant. Staining for vWF in extraglomerular vessels was nearly identical in kidneys showing acute and chronic rejection. Expression of CD62P was increased in extraglomerular vessels in allografts with chronic rejection, but the glomeruli showed little or no staining. There was no significant difference in the glomerular staining for CD62P or CD31 in organs showing acute and chronic rejection. Fibrinogen staining of glomerular mesangium was seen in kidneys with chronic rejection. Macrophages (CD68+) infiltrating glomeruli were more numerous in kidneys showing chronic rejection. CONCLUSION: Increased glomerular deposition of vWF in renal allografts showing chronic rejection, without increased staining for CD62P or CD31, suggests increased constitutive secretion of vWF from endothelial cells as a component of the mechanism of chronic rejection in our model.

Acute Disease↗