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Biomedical subjects

Y Cheng

Publications and source records attributed to Y Cheng.

At least 19 recordsLinked to original sources
PubMed2006

Effects of bile diversion in rats on intestinal sphingomyelinases and ceramidase.

Alkaline sphingomyelinase (Alk-SMase) and neutral ceramidase (N-CDase) in the intestinal microvillar membrane are responsible for dietary sphingomyelin digestion. The activities of the enzymes require the presence of bile salt, and the enzymes can be released into the gut lumen in active forms by bile salts and trypsin. It is unclear to what extent that the intestinal presence of bile salts is critical for the intraluminal activity of these enzymes. We compared the activities of Alk-SMase, N-CDase, and other types of SMases in control and permanently bile diverted rats. In the intestinal tract of control rats, the activity of Alk-SMase was profoundly higher than those of acid and neutral SMases. Bile diversion reduced Alk-SMase activity by 85% in the small intestinal content, and by 68% in the faeces, but did not significantly change the activity in the intestinal mucosa. Western blot showed a marked reduction of the enzyme in the intestinal lumen but not mucosa. N-CDase activities both in the intestinal mucosa and content were reduced by bile diversion. Bile diversion also decreased aminopeptidase N activity in the content and increased that in the mucosa, but had no effects on that of alkaline phosphatase. In conclusion, the presence of bile salts is important for maintaining high intraluminal levels of Alk-SMase and N-CDase, two key enzymes for hydrolysis of sphingomyelin in the gut. We speculate that the sphingomyelin hydrolysis in cholestatic conditions is impaired not only by reduced hydrolytic activity but also by deficient dissociation of the enzymes from the membrane.

Amidohydrolases↗
PubMed2006

Reentrant wetting transition on surfactant solution surfaces.

The wetting of polydimethylsiloxane oil drops on the surfaces of anionic surfactant sodium dodecylsulfate solutions is studied systematically by changing the bulk surfactant concentration. The wetting state changes from complete wetting to pseudopartial wetting at 0.3 cmc (critical micelle concentration) surfactant concentration and there is a reentrant transition back to complete wetting at 1.4 cmc. The measured free energy is consistent with the prediction of the wetting theory. The interaction potential minimum of the two surfaces of the oil film disappears at the reentrant point, which is speculated to be an effect of micelle formation in the solution.

Journal Article↗
PubMed2006

Preclinical and post-treatment changes in the HCC-associated serum proteome.

SELDI-based proteomic profiling of body fluids is currently in widespread use for cancer biomarker discovery. We have successfully used this technology for the diagnosis of hepatocellular carcinoma (HCC) in hepatitis C patients and now report its application to serial serum samples from 37 hepatitis C patients before development of HCC, with HCC and following radiofrequency ablation of the tumour. As with alpha-fetoprotein, an accepted biomarker for HCC, we hypothesised that HCC-associated proteomic features would 'return to normal' following successful treatment and the primary aim of our study was to test this hypothesis. Several SELDI peaks that changed significantly during HCC development were detected but they did not reverse following treatment. These data may be interpreted to suggest that the characteristic SELDI profile is not linearly related to tumour burden but may result from the progression of underlying liver disease or from the emergence of precancerous lesions. beta2-Microglobulin, a protein previously reported to be markedly elevated in patients with HCV related HCC, was also the most significantly HCC associated proteomic feature (m/z 11720) in this study.

Aged↗
PubMed2006

Study of the elastic constants in a La0.6Sr0.4MnO3 film by means of laser-generated ultrasonic wave method.

Two dimensional (2D) displacement field of the laser-generated ultrasonic wave is detected in a two-layered structure of La(0.6)Sr(0.4)MnO(3) (LSMO)/MgO system by means of the optical difference detection method. In order to obtain the elastic constants of the La(0.6)Sr(0.4)MnO(3) thin film, the displacement field of the laser-generated ultrasonic wave for the La(0.6)Sr(0.4)MnO(3)/MgO system is analyzed with finite element method (FEM). We further compare the theoretical simulations with the experimental results, and the elastic constants for the LSMO film, i.e., the Young's modulus and Poisson ratio, are obtained.

Journal Article↗
PubMed2006

Identification of serum biomarkers for colon cancer by proteomic analysis.

Colorectal cancer (CRC) is often diagnosed at a late stage with concomitant poor prognosis. Early detection greatly improves prognosis; however, the invasive, unpleasant and inconvenient nature of current diagnostic procedures limits their applicability. No serum-based test is currently of sufficient sensitivity or specificity for widespread use. In the best currently available blood test, carcinoembryonic antigen exhibits low sensitivity and specificity particularly in the setting of early disease. Hence, there is great need for new biomarkers for early detection of CRC. We have used surface-enhanced laser desorbtion/ionisation (SELDI) to investigate the serum proteome of 62 CRC patients and 31 noncancer subjects. We have identified proteins (complement C3a des-arg, alpha1-antitrypsin and transferrin) with diagnostic potential. Artificial neural networks trained using only the intensities of the SELDI peaks corresponding to identified proteins were able to classify the patients used in this study with 95% sensitivity and 91% specificity.

Adenocarcinoma↗
PubMed2006

High fat/refined carbohydrate diet enhances the susceptibility to spatial learning deficits in rats exposed to intermittent hypoxia.

BACKGROUND: Intermittent hypoxia during sleep (IH), as occurs in sleep disordered breathing (SDB), induces spatial learning deficits associated with regulation of transcription factors associated with learning and memory in the hippocampal CA1 region in rats. high fat refined carbohydrate diet (HF/RC) can induce similar deficits and associated changes in signaling pathways under normoxic conditions. METHODS: Sprague-Dawley adult male rats were fed either with (HF/RC) or low fat/complex carbohydrate diet (LF/CC) starting at post-natal day 30 for 90 days, and were then exposed for 14 days during light phase (12 h/day) to either normoxia (RA) or IH (21% and 10% O2 alternations every 90 s). Place-training reference memory task deficits were assessed in the Morris water maze. Total and ser-133 phosphorylated CREB were assessed in different brain regions by Western blotting and immunostaining in rats exposed to normoxia or IH and to LF/CC or HF/RC. RESULTS: Substantial decreases in CREB phosphorylation occurred in CA1 but not in motor cortex following either IH, HF/RC, and HF/RC + IH. Place-training reference memory task deficits were observed in rats exposed to IH and to HF/RC, and to a much greater extent in rats exposed to HF/RC + IH. CONCLUSIONS: Nutritional factors alter recruitment of transcription factors, possibly via oxidative-related pathways, and modulate the vulnerability of the CA1 region of the hippocampus to the episodic hypoxia that characterizes SDB, thereby enhancing neurocognitive susceptibility in SDB patients.

Animals↗
PubMed2006

Changes in the serum proteome associated with the development of hepatocellular carcinoma in hepatitis C-related cirrhosis.

Early diagnosis of hepatocellular carcinoma (HCC) is the key to the delivery of effective therapies. The conventional serological diagnostic test, estimation of serum alpha-fetoprotein (AFP) lacks both sensitivity and specificity as a screening tool and improved tests are needed to complement ultrasound scanning, the major modality for surveillance of groups at high risk of HCC. We have analysed the serum proteome of 182 patients with hepatitis C-induced liver cirrhosis (77 with HCC) by surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI). The patients were split into a training set (84 non-HCC, 60 HCC) and a 'blind' test set (21 non-HCC, 17 HCC). Neural networks developed on the training set were able to classify the blind test set with 94% sensitivity (95% CI 73-99%) and 86% specificity (95% CI 65-95%). Two of the SELDI peaks (23/23.5 kDa) were elevated by an average of 50% in the serum of HCC patients (P<0.001) and were identified as kappa and lambda immunoglobulin light chains. This approach may permit identification of several individual proteins, which, in combination, may offer a novel way to diagnose HCC.

Amino Acid Sequence↗
PubMed2006

Transcriptional profiling suggests that Barrett's metaplasia is an early intermediate stage in esophageal adenocarcinogenesis.

To investigate the relationship between Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC), we determined gene expression profiles of discrete pathological stages of esophageal neoplasia using a sequence-verified human cDNA microarray. Fifty one RNAs, comprising 24 normal esophagi (NE), 18 BEs, and nine EACs were hybridized to cDNA microarrays. Five statistical analyses were used for the data analysis. Genes showing significantly different expression levels among the three sample groups were identified. Genes were grouped into functional categories based on the Gene Ontology Consortium. Surprisingly, the expression pattern of BE was significantly more similar to EAC than to NE, notwithstanding the known histopathologic differences between BE and EAC. The pattern of NE was clearly distinct from that of EAC. Thirty-six genes were the most differentially modulated, according to these microarray data, in BE-associated neoplastic progression. Twelve genes were significantly differentially expressed in cancer-associated BE's plus EAC (as a single combined tissue group) vs noncancer-associated BE's. These genes represent potential biomarkers to diagnose EAC at its early stages. Our results demonstrate that molecular events at the transcriptional level in BE are remarkably similar to BE's-associated adenocarcinoma of the esophagus. This finding alarmingly implies that BE is biologically closer to cancer than to normal esophagus, and that the cancer risk of BE is perhaps higher than we had imagined. These findings suggest that changes modulated at the molecular biologic level supervene earlier than histologic changes, and that BE is an early intermediate stage in the process of EAC.

Adenocarcinoma↗
PubMed2006

The evaluation of the JEWEL project: an innovative economic enhancement and HIV prevention intervention study targeting drug using women involved in prostitution.

The JEWEL (Jewellery Education for Women Empowering Their Lives) pilot study examined the efficacy of an economic empowerment and HIV prevention intervention targeting illicit drug-using women (n=50) who were involved in prostitution in Baltimore, Maryland. The intervention was comprised of six 2-hour sessions that taught HIV prevention risk reduction and the making, marketing and selling of jewellery. Bivariate comparisons examined behaviour change pre- and 3-months post-intervention. The intervention's effect on the change in the number of sex trade partners from baseline to follow-up was explored with multiple linear regression. Participants were 62.0% African American, 5.0% were currently employed, and the median age was 39 years old (Inter Quartile Range [IQR]: 34-45). Women attended an average of six (IQR: 4.5-6.0) sessions. The women sold over $7,000 worth of jewellery in eleven sales. In comparing self-reported risk behaviours pre and 3-month post intervention participation, we found significant reductions in: receiving drugs or money for sex (100% versus 71.0%, p<0.0005); the median number of sex trade partners per month (9 versus 3, p=0.02); daily drug use (76.0% vs. 55.0%, p=0.003); the amount of money spent on drugs daily (US$52.57 versus US$46.71, p = 0.01); and daily crack use (27.3% versus 13.1.0%, p = 0.014). In the presence of other variables in a multivariate linear model, income from the jewelry sale was associated with a reduction in the number of sex trade partners at follow-up. The pilot indicated effectiveness of a novel, HIV prevention, economic enhancement intervention upon HIV sexual risk behaviours and drug utilization patterns.

Adolescent↗
PubMed2006

Testosterone induces apoptosis via Fas/FasL-dependent pathway in bone marrow-derived macrophages.

The detailed mechanisms behind the apoptosis of macrophages induced by testosterone are not clear. In the present study, we tried to delineate the effect of testosterone on the apoptosis of bone marrow-derived macrophages (BMMs) and the function of Fas/FasL (Fas ligand) pathway in this course. BMMs were stimulated with testosterone in the presence of macrophage colony stimulating factor (M-CSF) or without. Flow cytometry was used to quantify the apoptosis of BMMs. Real-time RT-PCR and Western blot were performed to analyze the expression of caspase-8, caspase-3, and poly(ADP-ribose) polymerase (PARP) during the Fas/FasL pathway. Our data showed that testosterone could induce the apoptosis of BMMs, similar to removing growth factor M-CSF from the culture medium. They were both associated with the enhanced expression of caspase-8, caspase-3, and PARP. And the phosphorothioate antisense oligodeoxynucleotides to fas-associated death domain protein (FADD) could block the expression of FADD, which is an upstream factor of caspase-8 in the Fas/FasL pathway. It led to the reduced obvious expression of caspase-8 and decreasing apoptosis of BMMs. These results suggest that the Fas/FasL pathway may play an important role in the testosterone-induced apoptosis of macrophages.

Animals↗
PubMed2006

Colonic amoebic abscess mimicking carcinoma of the colon.

Amoebiasis is an uncommon disease in developed countries. Its clinical presentation can be variable and non-specific, and the diagnosis can be easily overlooked. We report a case of colonic amoebic abscess mimicking advanced colonic cancer with acute intestinal obstruction and liver metastasis. The presentation, diagnosis, and treatment of amoebiasis are also reviewed.

Animals↗
PubMed2005

Prospective reliability of the STRokE DOC wireless/site independent telemedicine system.

The authors evaluated a site-independent telemedicine system. Telemedicine may be limited by the need for fixed connectivity. Wireless and site-independent technologies eliminate this limitation. Twenty-five stroke patients underwent evaluations by remote and bedside examiners. Ten of 15 (67%) NIH Stroke Scale and 9 of 11 (82%) Modified NIH Stroke Scale items showed excellent interrater reliability. Spearman correlations were > or =0.93. This Internet system is reliable and valid. Further studies should assess its use in acute stroke.

Adolescent↗
PubMed2005

Use of convalescent plasma therapy in SARS patients in Hong Kong.

In order to evaluate the efficacy of convalescent plasma therapy in the treatment of patients with severe acute respiratory syndrome (SARS), 80 SARS patients were given convalescent plasma at Prince of Wales Hospital, Hong Kong, between 20 March and 26 May 2003. Good outcome was defined as discharge by day 22 following the onset of SARS symptoms. Poor outcome was defined as death or hospitalization beyond 22 days. A higher day-22 discharge rate was observed among patients who were given convalescent plasma before day 14 of illness (58.3% vs 15.6%; P<0.001) and among those who were PCR positive and seronegative for coronavirus at the time of plasma infusion (66.7% vs 20%; P=0.001).

Blood Component Transfusion↗
PubMed2005

A novel locus for autosomal dominant hereditary gingival fibromatosis, GINGF3, maps to chromosome 2p22.3-p23.3.

Hereditary gingival fibromatosis (HGF) is a rare, benign disorder characterized by slowly progressive fibrous overgrowth of the gingiva. To date, two loci have been mapped in familial cases with autosomal dominant non-syndromic HGF: GINGF (MIM 135300) on chromosome 2p21-p22 and GINGF2 (MIM 605544) on chromosome 5q13-q22. Of the two loci, only SOS1 (son of sevenless one, MIM 182530) gene underlying GINGF locus has been identified. Ascertainment of a large Chinese family has allowed the mapping of a novel locus to 2p22.3-p23.3, GINGF3. Haplotype construction and analysis localized the new locus to an 11.4-cM interval between markers D2S2221 (telomeric) and D2S1788 (centromeric). The maximum two-point limit of detection (LOD) score of 3.45 (theta=0) and multipoint LOD score of 5.00 for marker D2S390 strongly supported linkage to this region. Thus, this genetic interval is distal to and does not overlap with the previously described locus, GINGF, on 2p21-p22.

Asian People↗
PubMed2005

Indoor/outdoor relationships for PM2.5 and associated carbonaceous pollutants at residential homes in Hong Kong - case study.

UNLABELLED: Six residences were selected (two roadside, two urban, and two rural) to evaluate the indoor-outdoor characteristics of PM(2.5) (aerodynamic diameter <2.5 microm) carbonaceous species in Hong Kong during March and April 2004. Twenty-minute-averaged indoor and outdoor PM(2.5) concentrations were recorded by DustTrak samplers simultaneously at each site for 3 days to examine diurnal variability of PM(2.5) mass concentrations and their indoor-to-outdoor (I/O) ratios. Daily (24-h average) indoor/outdoor PM(2.5) samples were collected on pre-fired quartz-fiber filters with battery-powered portable mini-volume samplers and analyzed for organic and elemental carbon (OC, EC) by thermal/optical reflectance (TOR) following the Interagency Monitoring of Protected Visual Environments (IMPROVE) protocol. The average indoor and outdoor concentrations of 24 h PM(2.5) were 56.7 and 43.8 microg/m(3), respectively. The short-term PM(2.5) profiles indicated that the penetration of outdoor particles was an important contributor to indoor PM(2.5), and a household survey indicated that daily activities were also sources of episodic peaks in indoor PM(2.5). The average indoor OC and EC concentrations of 17.1 and 2.8 microg/m(3), respectively, accounted for an average of 29.5 and 5.2%, respectively, of indoor PM(2.5) mass. The average indoor OC/EC ratios were 5.8, 9.1, and 5.0 in roadside, urban, and rural areas, respectively; while average outdoor OC/EC ratios were 4.0, 4.3, and 4.0, respectively. The average I/O ratios of 24 h PM(2.5), OC, and EC were 1.4, 1.8, and 1.2, respectively. High indoor-outdoor correlations (r(2)) were found for PM(2.5) EC (0.96) and mass (0.81), and low correlations were found for OC (0.55), indicative of different organic carbon sources indoors. A simple model implied that about two-thirds of carbonaceous particles in indoor air are originated from outdoor sources. PRACTICAL IMPLICATIONS: Indoor particulate pollution has received more attentions in Asia. This study presents a case study regarding the fine particulate matter and its carbonaceous compositions at six residential homes in Hong Kong. The characteristics and relationship of atmospheric organic and elemental carbon were discussed indoors and outdoors. The distribution of eight carbon fractions was first reported in indoor samples to interpret potential sources of indoor carbonaceous particles. The data set can provide significant scientific basis for indoor air quality and epidemiology study in Hong Kong and China.

Air Pollutants↗
PubMed2005

Early diffusion weighted imaging and expression of heat shock protein 70 in newborn pigs with hypoxic ischaemic encephalopathy.

OBJECTIVE: To establish a cerebral hypoxia ischaemic model in piglets and to explore the early diffusion weighted imaging (DWI) as well as the expression of heat shock protein 70 (HSP70) with hypoxic ischaemic encephalopathy (HIE). METHODS: Twenty four 3 day old piglets were permanently ligated common carotid arteries bilaterally and ventilated with 3% oxygen for 30 minutes, and their brains were examined at three hours, six hours, and 24 hours after hypoxic ischaemia with T2 weighted images and diffusion weighted images. Apparent diffusion coefficient (ADC) values were measured and HSP70 expression was detected in the central and peripheral regions of lesions. RESULTS: Abnormal signal intensity was detected on DWI and ADC maps in three hypoxic ischaemic groups. ADC values in the central lesions rapidly decreased, whereas ADC values in the peripheral regions reduced prominently at 24 hours after hypoxic ischaemia. There were significant differences (p<0.01) between ADC values of the central regions and the peripheral regions of lesions. The number of HSP70 positive cells was low at three hours, raised at the highest peak at six hours, and then rapidly decreased. There was statistical difference between HSP70 positive cells in the central regions and those in peripheral regions (p<0.01). CONCLUSION: DWI may identify more early lesions, and improve conspicuity in the acute setting. ADC values can be used as an objective measure for hypoxic ischaemic injury. Tissue reversibility can be further reflected according to the information of ADC values and HSP70 immunohistochemical staining.

Animals↗
PubMed2004

Repeat induced abortions and contraceptive practices among unmarried young women seeking an abortion in China.

OBJECTIVE: To determine the rates of repeated abortion and contraceptive use among unmarried young women seeking an abortion in China. METHODS: We used an anonymous self-administered questionnaire at abortion clinics in Beijing, Changsha, and Dalian from January to September 2000. RESULTS: Of 4547 unmarried young women seeking an abortion, 33.0% reported having had one previous induced abortion. Of those who had had more than one abortion, only 29.7% used a contraceptive method at their first sexual intercourse after the procedure; and of the 446 women who chose contraception, 41.3% used the traditional methods of withdrawal or rhythm. Although 65.0% of the young women had used condoms at least once, only 9.6% did so consistently and correctly; 47.7% of the current pregnancies were associated with nonuse of any contraceptive, and 52.3% were related to contraceptive failure. CONCLUSION: The rate of unmarried young women seeking repeated abortions was high in China on 2000. The rate of consistent condom use was low, and the rate of contraceptive failure was higher.

Abortion, Induced↗