Biomedical subjects

Sheng Chen

Publications and source records attributed to Sheng Chen.

47 records · Page 3Linked to original sources

PubMed2003

Basal and inducible levels of Hsp70 in patients with acute heat illness induced during training.

Heat shock proteins (Hsps) or stress proteins, and, in particular, the inducible, cytosolic Hsp70, represent a highly conserved response to heat exposure and to a variety of noxious stimuli. Many investigations have shown correlations between the aberrant expression of Hsps and disease states. Whether the basal and inducible levels of Hsp70 are of any biological significance in patients with heat-induced diseases remains unknown. In the present study, we compared the basal and inducible levels of Hsp70 by flow cytometry in lymphocytes of patients with heat-induced diseases and after recovery from this disease, and in matched controls. Both groups comprised individuals who exercised by running in the same hot environment. The level of inducible Hsp70 was also measured after a heat treatment of lymphocytes in vitro. The results show that there is variation of basal and inducible Hsp70 levels among individuals. However, the group of patients suffering from heat-induced illnesses in May shows a significantly higher basal (P = 0.02) level of Hsp70 than does the control group. Individuals who have an increased level of Hsp70 may be more sensitive to heat or may respond differently. The level of Hsp70 may represent a biomarker to evaluate whether they are more susceptible to stresses than other individuals. Interestingly, the basal level of Hsp70 is higher in both the patient group and the control group in November than in May. In fact, the basal levels of Hsp70 in the patient and control groups are essentially the same in November, perhaps reflecting the successful stress conditioning of both groups.

Adult↗

PubMed2003

Meningioangiomatosis: report of three cases and review of the literature.

Meningioangiomatosis is a rare condition, probably hamartomatous, characterized by proliferation of capillary-sized vessels, meningothelial cells, and fibroblasts within the cortex of the brain. Lesions may be single or diffuse and may be associated with neurofibromatosis type II. Clinically it presents with seizures but may be asymptomatic throughout life. We report 3 cases of meningioangiomatosis, 2 localized and 1 diffuse, all with different clinical manifestations. Differential diagnoses are discussed with a review of the literature. Since this condition is rare, close clinico-pathological correlation is essential. A correct diagnosis avoids further aggressive treatment.

Adolescent↗

PubMed2003

[Co-detection of P21, P53 and HSP70 and their possible role in diagnosis of polycyclic aromatic hydrocarbons (PAHs)-related lung cancer].

OBJECTIVE: To explore the biomarkers of early diagnosis in patients with polycyclic aromatic hydrocarbons (PAHs)-related lung cancer for the application to detection of occupational lung cancer or related lung cancer. METHODS: Western dot blotting was used to explore the expression of ras, p53 and heat stress protein 70 (HSP70) in 29 patients with PAHs-related lung cancer (LC), and 28 patients with non-cancerous pulmonary disease, and 30 healthy controls. RESULTS: The positive detection rates of P21, P53, and HSP70 in LC group (58.62%, 34.48%, 41.38% respectively) were higher than those in non-cancerous pulmonary disease group (14.29%, 7.14%, 10.71% respectively, P < 0.01). The sensitivity of P21, P53 and HSP70 were 58.62%, 34.48% and 41.38% respectively, negative predictive value (NPV) were 68.42%, 78.05% and 63.04% respectively. The co-detection of the three proteins mentioned above produced a sensitivity of 82.76% with a NPV of 78.26% (P < 0.05). Of 18 cases of LC with negative cytology, 13 (72.22%) were found HSP21, P53 or HSP70 positive. CONCLUSIONS: Co-detection of the P21, P53, and HSP70 may be used as the screening marker for diagnosis of PAHs-related lung cancer, and may supplement the diagnostic value of conventional cytology.

Aged↗

PubMed2002

Association of HSP70 and genotoxic damage in lymphocytes of workers exposed to coke-oven emission.

Heat shock proteins (Hsps) have been reported to protect cells, tissues, and organisms against damage from a wide variety of stressful stimuli. Whether they protect against deoxyribonucleic acid (DNA) damage in individuals exposed to environmental stresses and chemical carcinogens is unknown. In the study, we investigated the association between Hsp70 levels (the most abundant mammalian Hsp) and genotoxic damage in lymphocytes of workers exposed to coke-oven emission using Western dot blot and 2 DNA damage assays, the comet assay and the micronucleus test. The data show that there is a significant increase in Hsp70 levels, DNA damage score, and micronucleus rates in lymphocytes of workers exposed to coke-oven emission as compared with the control subjects. Furthermore, there was a significant negative correlation of Hsp70 levels with DNA damage scores in the comet assay (r = -0.663, P < 0.01) and with micronucleus rates (r = -0.461, P < 0.01) in the exposed group. In the control group, there was also a light negative correlation between Hsp70 with DNA damage and micronuclei rate (r = -0.236 and r = 0.242, respectively), but it did not reach a statistically significant level (P > 0.05). Our results show that individuals who had high Hsp70 levels generally showed lower genotoxic damage than others. These results suggest a role of Hsp70 in the protection of DNA from genotoxic damage induced by coke-oven emission.

Adult↗

PubMed2002

Effect of manganese on heat stress protein synthesis of new-born rats.

AIM: To study the effect of manganese (Mn) on heat stress protein 70 (HSP70) synthesis in the brain and liver of new-born rats whose mother-rats were exposed to Mn. METHODS: 32 female rats were randomly divided into four groups. One group was administrated with physiological saline only as control group, the other three groups were administrated with 7.5, 15 and 30 mg x kg(-1) manganese chloride (MnCl2) by intraperitioneal injection every two days for two weeks. After delivery, the mother-rats received MnCl2 unceasingly for a week with the same method. Then the contents of Mn Zn Cu and Fe in the livers of the new-born rats were determined by atomic absorption spectroscopy; The level of HSP70 in the brains and the livers of the new-born rats as detected by Western-dot-blotting, and the SOD activities were measured simultaneously. RESULTS: The contents of Mn in the livers of new-born rats of the experimental groups(respective 1.38+/-0.18, 2.73+/-0.65,3.44+/-0.89 microg x g(-1)) were significantly increased compared with the control group(0.88+/-0.18 microg x g(-1); P<0.01); The contents of Fe in the livers of new-born rats of 15 and 30 mg x kg(-1) experimental groups (426+/-125, 572+/-175 microg x g(-1), respectively) were significantly increased compared with the control group(286+/-42 microg x g(-1); P<0.05); the levels of Zn in the livers of the new-born rats of three experimental groups(254+/-49, 263+/-47, 213+/-28 microg x g(-1), respectively) were lower than those of the control group(335+/-50 microg x g(-1); respective P<0.05, P<0.01); and the levels of Cu showed no significant difference among the four groups(three experimental groups: 75+/-21, 68+/-241 and 78+/-18 microg x g(-1); control group: 83+/-9 microg x g(-1); P<0.05). There was a significant increase in the levels of HSP70 in the brains of new-born rats of the 30 mg x kg(-1) group (19.5 x 10(3)+/- 1.3 x 10(3)A;control group:14.3 x 10(3)+/-1.4 x 10(3)A; P<0.01) and the levels of HSP70 in the livers of new-born rats of three experimental groups(respective 19.6 x 10(3)+/- 3.9 x 10(3)A,18.5 x 10(3)+/-3.8 x 10(3)A, 22.4 x 10(3)+/-1.9 x 10(3)A) also increased than control group(13.3 x 10(3)+/-1.0 x 10(3)A;P<0.01), but the SOD activities showed no significant difference among brains of the four groups (experimental groups: 5.04+/-0.43, 4.83+/-0.48, 4.60+/-0.84 ku x g(-1); control group: 4.91+/-0.37 ku x g(-1); P<0.05). The SOD activities in the livers of 15 mg x kgP< group(5.41+/-0.44 ku x gP<) was lower than the control group(5.95+/-0.36 ku x gP<; P<0.05). CONCLUSION: While mother-rats were exposed to manganese, the metabolisms of Mn Zn and Fe of new-born rats in the livers were influenced and were situated in a stress status, thus HSP70 syntheses is induced in the brains and livers of new-born rats, but the mechanism of this effect in the developmental toxicity of Mn remains to be further studied.

Animals↗

PubMed2002

The role of endoscopic retrograde cholangiopancreatography in perioperative period of laparoscopic cholecystectomy.

OBJECTIVE: To explore the indications and the value of endoscopic retrograde cholangiopancreatography (ERCP) in perioperative phase of laparoscopic cholecystectomy. METHODS: From January 1998 to April 1999, a total of 1500 consecutive laparoscopic cholecystectomies were analyzed. The indications for preoperative group (n=33) included elevated bilirubin level and alkaline phosphatase level, jaundice, pancreatitis, abnormal liver function, dilated bile duct and/or stones on ultrasound or CT. The indications for postoperative group (n=20) included clinical signs or symptoms as well as common bile duct stones demonstrated by intraoperative cholangiography. RESULTS: Preoperative ERCP for 32 patients (2.1%) showed abnormalities in 12 (37%). Postoperative ERCP for 20 patients (1.3%) demonstrated abnormalities in 14 (70%). Super-selected criteria for preoperative ERCP would predict more than 66% ductal stones. Endoscopic sphincterectomy and duct stones clearance were performed in all 16 patients with documented common bile duct stones. The morbidity was confined in 2 patients with self-limited pancreatitis (3%). CONCLUSIONS: Using super-selected criteria to select patients for preoperative ERCP can avoid unnecessary ERCP. As soon as postoperative patients have clinical signs or symptoms, endoscopic treatment should be performed.

Adolescent↗

PubMed2002

[Study on the morphological damage and cell apoptosis of nerve tissue in mice exposed to benzo[a]pyrene].

OBJECTIVE: To study the toxicological effects of benzo[a]pyrene(BaP) on mammalian animal's nerve tissue. METHODS: 50 Kunming mice were divided into 5 groups at random, the exposed groups(3 dose level groups), the vehicle control group and standard control group. Every group got 10 mice. The exposed groups were treated by intraperitoneal injection with BaP dissolved in vegetable oil at 7.8, 3.2 and 1.3 mg/kg respectively, 4 times/week, for 10 weeks, the vehicle control group were given vegetable oil and the standard control group were not given any treatment. All the mice were anesthetized with 0.02 mol/L pentobarbital and infused with 1.33 mol/L paraformaldehyde dissolved in PBS through heart after 10 weeks. Then the brain, spinal cord and sciatic nerve were removed. Slices of these tissues were made and morphological changes were observed by optical microscope and electron-microscope. Cell appoptosis was examined by TUNEL(TdT-mediated x-dUTP nick end labeling) method. RESULTS: Morphological observations showed tissue injury in BaP exposed groups. There were focal necrosis areas found in the high-dose group. The cell apoptosis rates in 3.2 and 1.3 mg/kg groups were 90.02%-94.22% and 62.45%-77.54% respectively, significantly higher than those of vehicle control group and standard control group(4.60%-5.57%). CONCLUSION: BaP is neurotoxic. It could damage the nerve tissue as well as induce DNA breaks and cell apoptosis.

Animals↗

PubMed1998

Robust maximum likelihood training of heteroscedastic probabilistic neural networks.

We consider the probabilistic neural network (PNN) that is a mixture of Gaussian basis functions having different variances. Such a Gaussian heteroscedastic PNN is more economic, in terms of the number of kernel functions required, than the Gaussian mixture PNN of a common variance. The expectation-maximisation (EM) algorithm, although a powerful technique for constructing maximum likelihood (ML) homoscedastic PNNs, often encounters numerical difficulties when training heteroscedastic PNNs. We combine a robust statistical technique known as the Jack-knife with the EM algorithm to provide a robust ML training algorithm. An artificial-data case, the two-dimensional XOR problem, and a real-data case, success or failure prediction of UK private construction companies, are used to evaluate the performance of this robust learning algorithm.

Journal Article↗

PubMedDate not supplied

Neuroprotective therapy in Parkinson disease.

During the past decade, there has been a remarkable progress in our understanding of the biology of Parkinson disease (PD), which has been translated into searching for novel therapy for PD. Much focus is shifted from the development of drugs that only relieve PD symptoms to new generation of remedies that can potentially protect dopaminergic neurons and modify the disease course. Several novel therapeutic approaches have been tested in preclinical experiments and in clinical trials, including molecules targeting on genes involved in the pathogenesis of the disease, neurotrophic factors critical for dopaminergic neuron survival and function, new generation of dopamine receptor agonists that may possess neuroprotective effects, and agents of antioxidation, antiinflammation, and antiapoptosis. The results of these studies will shed new light to our hope that PD can be cured in the future.

Apoptosis↗

PubMedDate not supplied

Optimization of block-floating-point realizations for digital controllers with finite-word-length considerations.

The closed-loop stability issue of finite-precision realizations was investigated for digital controllers implemented in block-floating-point format. The controller coefficient perturbation was analyzed resulting from using finite word length (FWL) block-floating-point representation scheme. A block-floating-point FWL closed-loop stability measure was derived which considers both the dynamic range and precision. To facilitate the design of optimal finite-precision controller realizations, a computationally tractable block-floating-point FWL closed-loop stability measure was then introduced and the method of computing the value of this measure for a given controller realization was developed. The optimal controller realization is defined as the solution that maximizes the corresponding measure, and a numerical optimization approach was adopted to solve the resulting optimal realization problem. A numerical example was used to illustrate the design procedure and to compare the optimal controller realization with the initial realization.

Analog-Digital Conversion↗

PubMedDate not supplied

Effect of hepatitis C virus core protein on the molecular profiling of human B lymphocytes.

Hepatitis C virus (HCV) core protein features many intriguing properties and plays a pivotal role in cellular immunity, cell growth, apoptosis, cell transformation, and eventually in tumor development. However, the role of B cells, the primary players in the humoral immune response, during HCV infection is largely unknown. To explore the molecular effects of HCV core on human B cells, we conducted gene expression profiling of serial RNA samples from B cells that were infected with adenovirus harboring full-length HCV core protein and beta-galactosidase as a reference using a microarray platform containing 22,149 human oligo probes. The entire experiment was performed in duplicate in B lymphocytes that were isolated from two individual donors and incubated for up to 3 days after infection with adenovirus expressing HCV core protein to identify dynamic gene expression patterns. Differential expression of representative genes was validated by quantitative RT-PCR. We found that HCV core significantly inhibited B-lymphocyte apoptosis. We showed a dramatic downregulation of MHC class II molecules in B cells expressing HCV core, whereas the expression of immunoglobulin genes was not significantly altered. Moreover, genes associated with leukemia and B-lymphoma were consistently upregulated by HCV core. In contrast, downregulation of caspase-1 and caspase-4 was found to be associated with core's ability to prevent B-lymphocyte apoptosis. In summary, we have identified several clusters of genes that are differentially expressed in human B lymphocytes expressing HCV core, suggesting a potential impairment of antigen processing and presentation, which may provide more insights into HCV infection in B lymphocytes.

Adenoviridae↗