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Biomedical subjects

X S Chen

Publications and source records attributed to X S Chen.

At least 37 records · Page 2Linked to original sources

Leprosy in China: delay in the detection of cases.

In a national survey in China, 27,928 cases of leprosy detected by the health authorities between 1984 and 1998 were investigated. The delay between onset of symptoms (estimated from each case's recall) and confirmed diagnosis was < or = 2 years for 55.1% of the new patients but > 10 years for 7.0%, with a median value, overall, of 22.0 months. The median delay was longer: (1) for the multibacillary cases than the paucibacillary; (2) among farmers than among factory workers; (3) among some nationalities than among others (being longest among the Tu and shortest among the Wei); and (4) for some methods of case-detection than for others. Over the study period, the mean delay decreased with time. The delay was greatest in the areas where leprosy was endemic and/or where access to health services was poor. The later the cases were detected the more likely they were to show disability. Leprosy cases are still going undetected in China, although, over the last 14 years, case-finding has significantly improved. Age, occupation, nationality, leprosy type and detection method all appear to affect the delay.

Adolescent↗

Leprosy in children: a retrospective study in China, 1986-1997.

Leprosy in children forms an important link in the natural evolution and the epidemic profile of the disease. The study was undertaken on 1208 child cases detected during the years 1986-1997 in China. The number of child cases constituted 3-4 per cent of the total during this period although the incidence rates decreased dramatically. The detection rate significantly increased with age, and the average rate of 0.027 per 100,000 population was much lower than that in adults. In the pediatric cases, children in the younger age group had a higher prevalence of solitary lesions and lower prevalence of reactions and disabilities than the older group. A total of 70.01 per cent of the affected cases were infected by intra-familial contact, 35.60 per cent were detected by contact examination, and another 22.86 per cent by active surveys. The results of the study suggest that leprosy in children is not a public health problem at the present in China, but the regular screening of children in the family of patients is still one of the important ways to detect child cases and should be recommended.

Adolescent↗

Epidemiologic trends of sexually transmitted diseases in China.

OBJECTIVE: To describe the current epidemiology of sexually transmitted diseases (STDs), we analyzed the time trends in distribution of reported cases of STDs in China from 1989 to 1998. STUDY DESIGN: Based on the computerized database of the National System of STD Surveillance, a retrospective study of STD cases reported from 1989 to 1998 was carried out. RESULTS: From 1989 to 1998, STD incidence increased significantly in men and women and demonstrated nonlinear growth trends, with the exception of gonorrhea incidence. Between 1990 and 1998, the incidence increased more in females (4.20 times) than that in males (3.79 times). Syphilis incidence increased approximately 20 times during this period at an average annual rate of 52.7%. Gonorrhea incidence increased 2.6 times during this period at an average annual rate of 11.4%, which reached a plateau from 1994 to 1997. Extramarital transmission as source of STD infection has significantly increased from 1995 to 1998. CONCLUSION: The incidence of STDs has continued to increase in China from 1989 to 1998. The epidemic patterns are different from rates in developed counties in which behavior interventions have been successfully implemented, suggesting the need for active behavioral-intervention programs in China.

Adolescent↗

A comparison of topical application of penciclovir 1% cream with acyclovir 3% cream for treatment of genital herpes: a randomized, double-blind, multicentre trial.

Genital herpes simplex virus (HSV) infection, a sexually transmitted disease (STD), is the commonest cause of ulcerative genital infections among the young and adult population. The significant association of genital ulceration and transmission of human immunodeficiency virus (HIV) has been shown in many studies. To explore the potential efficacy of topical treatment of genital herpes with penciclovir cream, a randomized, double-blind, multicentre, acyclovir-controlled Phase II clinical trial of penciclovir 1% cream 5 times daily up to 7 days for suppression of genital herpes was conducted in China. A total of 205 patients aged 20-59 years (mean age 36.0+/-8.8 years for acyclovir and 34.8+/-8.4 years for penciclovir) with a clinical diagnosis of genital herpes were randomly allocated to one of the 2 parallel treatment groups and used for analysis. Clinical assessment were made before treatment and followed up at every visit during the study. Our results show that there was an encouraging improvement simultaneously in the 2 groups although no significant differences in clinical efficacy with respect to clinical cure rate, and times to healing, resolution of all symptoms, absence of blisters, cessation of new blisters, crusting, and loss of crust between penciclovir and acyclovir groups in terms of primary, non-primary and total patients were found. However a significantly shorter time to crusting was found in primary penciclovir group when compared with primary acyclovir group. Adverse experience was generally infrequent and mild, and was comparable in the 2 treatment groups. Based on these preliminary clinical findings, further evaluation of penciclovir 3% cream for topical treatment of genital herpes is planned.

Acyclovir↗

Computerization of leprosy records: national leprosy recording and reporting system in China.

This paper describes the national system of leprosy recording and reporting in China and the computerization of records. The system was designed for data collection at local level and data entry by optically scanned or manual mode as well as for sophisticated data analysis. The major functions include data entry, data check, sum-up, maintenance, communication, inquiry, statistics, graph and print. A total of 17 options for epidemiological and clinical data analysis are available. Through the implementation for about 10 years, the system has gained widespread acceptance. This acceptance would facilitate introduction of computer analysis to other leprosy projects and other disease control programs in China. Up to 1998, a database of more than 740,000 records covering all the leprosy patients detected since 1949 had been established by this system.

Adolescent↗

Studies on risk of leprosy relapses in China: relapses after treatment with dapsone monotherapy.

Based upon the data from the Chinese National System for Leprosy Surveillance, this paper reports on the relapses in 297,343 leprosy patients [multibacillary (MB) 106,518, paucibacillary (PB) 190,825] cured by dapsone monotherapy. A total of 11,055 (MB 8675, PB 2380) patients relapsed during an accumulated follow-up period of 4,229,050 patient-years (PY), giving an overall relapse rate of 3.72 per 100 cases or 2.61 per 1000 PY, i.e., 8.14% or 5.91 per 1000 PY over an average follow-up period of 13.8 +/- 8.4 years in MB patients and 1.25% or 0.86 per 1000 PY over an average period of 14.5 +/- 8.9 years in PB patients. For either the overall relapse rate per 100 cases or per 1000 PY, the differences between MB and PB patients were statistically significant, except during 36-40 years of follow up. For both MB and PB patients, the relapse rates showed consistently significant decreases year by year, particularly in PB patients whose relapse rate per 1000 PY was 1.21 in year 10 of follow up; whereas it remained more than 10 per 1000 PY in MB patients. In view of that, the overall relapse rates in MB and PB patients cured by dapsone monotherapy were acceptably low, and most of these patients have been followed up for more than a mean incubation period of observed dapsone relapse. Along with the further extension of follow up, the risk of relapse in dapsone-cured patients will not be expected to increase. This conclusion should be considered when planning policy for the management of patients released from dapsone monotherapy.

China↗

Studies on risk of leprosy relapses in China: relapses after treatment with multidrug therapy.

Based upon the data from the Chinese National System for Leprosy Surveillance, this paper reports on the relapses in 47,276 leprosy patients cured by or released from WHO-recommended multidrug therapy (WHO/MDT). The overall relapse rate was 0.73/1000 patient-years (PY). There was a statistically significant difference in the relapse rates of WHO/MDT-MB (0.61/1000 PY) and WHO/MDT-PB (1.04/1000 PY) (chi 2 = 15.7, p < 0.01) patients. For multibacillary (MB) patients, the relapse rate in patients treated with fixed-duration MDT (0.56/1000 PY) was comparable with that in patients treated with MDT until skin-smear negativity (0.73/1000 PY) (chi 2 = 2.20, p > 0.05). Our present study suggests that fixed-duration MDT is a cost-effective regimen for the treatment of leprosy in China. The present results also show that relapse of leprosy is acceptably low and has not yet become a serious clinical or public health problem but, based upon the incubation of relapse in MDT patients, it is necessary to encourage annual follow up for at least 5 years for paucibacillary (PB) and 10 years for MB patients after being released from WHO/MDT.

China↗

Human 12(R)-lipoxygenase and the mouse ortholog. Molecular cloning, expression, and gene chromosomal assignment.

Expressed sequence tag information was used to clone the full-length sequence for a new human lipoxygenase from the B cell line CCL-156. A related mouse sequence with 83% nucleotide identity to the human sequence was also cloned. The human lipoxygenase, when expressed via the baculovirus/insect cell system produced an approximately 80-kDa protein capable of metabolizing arachidonic acid to a product identified as 12-hydroxyeicosatetraenoic acid by mass spectrometry. Using chiral phase-high performance liquid chromatography, the product was identified as >98% 12(R)-hydroxyeicosatetraenoic acid as opposed to the S-stereoisomer formed by all other known mammalian lipoxygenases. The single copy human 12(R)-lipoxygenase gene was localized to the chromosome 17p13 region, the locus where most other lipoxygenase genes are known to reside. By reverse transcription-polymerase chain reaction, but not by Northern blot, analysis the 12(R)-lipoxygenase mRNA was detected in B cells and adult skin. However, the related mouse lipoxygenase mRNA was highly expressed in epidermis of newborn mice and to a lesser extent in adult brain cortex. By in situ hybridization the mouse lipoxygenase gene was demonstrated to be temporally and spatially regulated during embryogenesis. Expression was induced at embryonic day 15.5 in epidermis, nasal epithelium, and surface of the tongue. These results broaden the mammalian lipoxygenase family to include a 12(R)-lipoxygenase whose biological function remains to be determined.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

Determinants of 5-lipoxygenase nuclear localization using green fluorescent protein/5-lipoxygenase fusion proteins.

5-Lipoxygenase catalyzes the first two steps in the biosynthesis of leukotrienes, potent extracellular mediators of inflammation and allergic disorders. The unanticipated observation of 5-lipoxygenase in the nucleus of some cell types including bone marrow-derived mast cells (Chen, X. S., Naumann, T. A., Kurre, U., Jenkins, N. A., Copeland, N. G., and Funk, C. D. (1995) J. Biol. Chem. 270, 17993-17999) has raised speculation about intranuclear actions of leukotrienes or the enzyme itself. To explore the entry of 5-lipoxygenase into the nucleus we have transfected various cell types with expression vectors encoding native 5-lipoxygenase and green fluorescent protein/5-lipoxygenase (GFP-5LO) fusion proteins. 5-Lipoxygenase and green fluorescent protein/5-lipoxygenase co-localized with the nuclear DNA stain Hoechst 33258 in each cell type. The three main basic regions of 5-lipoxygenase were incapable of acting as "classical" nuclear localization signal sequences. Mutations that abolished enzyme activity/non-heme iron resulted in proteins that would no longer enter the nucleus. An NH2-terminal 5-lipoxygenase fragment of 80 residues was sufficient for directing nuclear localization of green fluorescent protein but not cytosolic pyruvate kinase. The combined data suggest that 5-lipoxygenase enters the nucleus not by a classical nuclear localization signal but by a non-conventional signal located in the predicted beta-barrel domain that may be masked by structural alterations.

Arachidonate 5-Lipoxygenase↗

Interaction of polyomavirus internal protein VP2 with the major capsid protein VP1 and implications for participation of VP2 in viral entry.

A complex of the polyomavirus internal protein VP2/VP3 with the pentameric major capsid protein VP1 has been prepared by co-expression in Escherichia coli. A C-terminal segment of VP2/VP3 is required for tight association, and a crystal structure of this segment, complexed with a VP1 pentamer, has been determined at 2.2 A resolution. The structure shows specific contacts between a single copy of the internal protein and a pentamer of VP1. These interactions were not detected in the previously described structure of the virion, but the location of VP2 in the recombinant complex is consistent with features in the virion electron-density map. The C-terminus of VP2/VP3 inserts in an unusual, hairpin-like manner into the axial cavity of the VP1 pentamer, where it is anchored strongly by hydrophobic interactions. The remainder of the internal protein appears to have significant flexibility. This structure restricts possible models for exposure of the internal proteins during viral entry.

Amino Acid Sequence↗

[Observation of female gametophyte development of Ginkgo biloba and its protoplast isolation and culture].

Results of observation showed that the female gametophyte of Ginkgo biloba was at the coenocytic stage from March 30ty to May 30ty. A density of 6-8 x 10(5) protoplasts/ml with a viability of 87.3% was achieved when the female gametopytes collected from May 8th to 15th were treated with 0.5% cellulase Onzuka R-10, 0.5% Pectolyase for 4-5 hours. The thin-layer liquid Murashige and Tuker medium modified by omitting ammonium ions and supplementing with glutamine 1000 mg/L, Vc 5 mg/L, benzyladenine 1.0 mg/L and naphthaleneacetic acid 3.0 mg/L was used for the protoplast culture and multiple cell colonies were obtained.

Cells, Cultured↗

[Progress in the study of mammalian selenoprotein].

Selenium is an essential trace element for animals and humans. Selenium exerts its biological function largely through selenoproteins. Up to now nine selenoproteins' cDNAs have been cloned and sequenced, which are cellular glutathione peroxidase (cGPX), extracellular glutathine peroxidase(eGPX), phospholipid hydroperoxidase glutathione peroxidase(PHGPX), gastrointestinal glutathione peroxidase (GPX-GI), type I iodothyronine 5'-deiodinase (ID I), type 2 iodothyronine 5'-deiodinase(ID II), type III iodothyronine 5-deiodinase(ID III), selenoprotein P (Se-P) and selenoprotein W. In all these selenoproteins Se is incorporated into the protein molecule via the selenocysteinyl-tRNA which recognizes the specific UGA codons in mRNA to insert selenocysteine into the primary structure of selenoproteins.

Animals↗

Changes in myocardial thyroid hormone metabolism and alpha-glycerophosphate dehydrogenase activity in rats deficient in iodine and selenium.

Weanling Wistar rats were fed on diets prepared from grain from areas deficient in I and Se where Keshan disease in endemic. Rats were divided into four groups, each of twelve rats, and received a diet supplemented with: I, Se, I + Se or nothing. At 8 weeks after weaning, myocardial alpha-glycerophosphate dehydrogenase (EC 1.1.1.8; alpha-GPD) activity and indices of Se and thyroid hormone status were determined. The group supplemented with iodine had increased plasma thyroxine levels. There was no difference in plasma triiodothyronine concentration between the groups but triiodothyronine levels in heart were reduced in the Se-supplemented group. Se supplementation increased myocardial glutathione peroxidase activity (EC 1.11.1.9) and the type I 5'-deiodinase (EC 3.8.1.4) activity in rat liver, but no type I 5'-deiodinase activity was detected in heart. alpha-GDP activity in heart was increased in group supplemented with Se, I or both. There was a significant relationship (P < 0.05) between myocardial alpha-GDP activity and plasma thyroxine levels but not between alpha-GDP and myocardial glutathione peroxidase activity. The results indicate that iodine may be more important than Se in energy metabolism in the myocardium, which may give a new insight for the study of the aetiology of Keshan disease in areas where foodstuffs are deficient in both Se and I.

Analysis of Variance↗

Facilitated oxygen transport with modified and encapsulated hemoglobins across non-flowing solution membrane.

The oxygen-transporting capability of modified and encapsulated hemoglobins and red cells is discussed from a physico-chemical standpoint in order to design oxygen-delivering fluids. The oxygen diffusion coefficient toward oxygen-deficient sites was estimated by measuring the oxygen flux across thin solution membranes of hemoglobin, polymerized hemoglobin, liposome-encapsulated hemoglobin, and red cells. Oxygen flux was enhanced several times over that of nitrogen for the hemoglobin and red cell solution with ca [Hb] = 10 and 15 g/dl, respectively. The enhancement in the oxygen diffusion is ascribed to the facilitated transport of oxygen via the hemoglobins. This was in contrast to the simple and physical oxygen-diffusivity in response to its concentration gradient, in the absence of hemoglobins. The flux of the oxygen transport was in the order of hemoglobin > red cells > polymerized hemoglobin > encapsulated hemoglobin, which was ascribed to the facilitated transport efficiencies of oxygen with hemoglobins in a non-flowing or stationary solution.

Animals↗

[Effect of jiangtangkang on blood glucose, sensitivity of insulin and blood viscosity in non-insulin dependent diabetes mellitus].

OBJECTIVE: To study the hypoglycemic effect of Jiangtangkang (JTK), a Chrysanthemum product and its influence on sensitivity of insulin in non-insulin dependant diabetes mellitus (NIDDM). METHODS: Newly discovered (71 cases) and poorly controlled (117 cases) NIDDM were divided to JTK, 8 g each time, 3 times per day, and the control (Glibenclazide in newly discovered, no treatment in poorly controlled) group respectively. RESULTS: After 2 months of treatment, the fasting blood glucose (FBG), postprandial blood glucose (PBG), glucosylated hemoglobin (GHb) improved remarkably and insulin of plasma remained unchanged in JTK group, their blood viscosity and triglyceride decreased after 6-month reatment, the FBG, PBG lowered in the control group while their viscosity and lipids were unaffected. Insulin tolerance test on newly discovered NIDDMs showed an increased sensitivity to insulin, their serum chromium elevated, and the urinary albumin in poorly controlled persons lowered significantly. CONCLUSIONS: JTK might improve the sensitivity to insulin and decrease the blood viscosity in NIDDM.

Adult↗

An investigation of attitudes, beliefs and behaviour of leprosy patients, family members and PHC workers towards multidrug therapy in Yangzhou and Dongtai Districts of China.

To improve the operational efficiency of multidrug therapy (MDT) implementation in rural areas, an investigation into the attitudes, beliefs and behaviour of leprosy patients and their family members as well as primary health care (PHC) workers towards MDT was carried out in Yangzhou and Dongtai Districts of China. A sample of 370 leprosy patients, 594 family members and 730 PHC workers was interviewed or investigated individually using questionnaires. The results showed that: 1, the presently used MDT is acceptable to a wide range of patients although a small number of patients have various problems in their treatment; 2, the patients' habit in daily drug administration, their awareness of the risk of default and confidence in MDT have a positive influence in increasing drug compliance; and 3, the supervision and encouragement of family members to patients' treatment which is associated with their knowledge on MDT is also beneficial to patients' drug compliance. However, only half of the PHC workers had a basic knowledge of MDT and a desire to participate in MDT implementation, a finding which clearly calls for urgent attention and improvement. In order to ensure the effective implementation of MDT, there is a need to educate leprosy patients and their family members as well as PHC workers to establish the patients' correct awareness of MDT, obtain the family support and motivate the PHC workers.

Adult↗