Search PubMed⌕ Search

Biomedical subjects

W Chen

Publications and source records attributed to W Chen.

At least 1,117 records · Page 62Linked to original sources
PubMed1991

Presence of identical mitochondrial proteins in unstimulated constitutive steroid-producing R2C rat Leydig tumor and stimulated nonconstitutive steroid-producing MA-10 mouse Leydig tumor cells.

The acute regulation of steroidogenesis in steroidogenic tissues requires de novo protein synthesis. It is believed that these newly synthesized proteins are instrumental in the delivery of the substrate, cholesterol, to the inner mitochondrial membrane where the cholesterol side-chain cleavage complex converts cholesterol to pregnenolone. A number of studies have attempted to characterize the protein(s) synthesized in response to hormone stimulation and, hence, function in the delivery of cholesterol to the cholesterol side-chain cleavage complex. While a number of potential protein candidates have been described, there is at present no unequivocal evidence which indicates that they are involved in steroidogenic regulation. We and others have described proteins that are induced in a variety of steroidogenic tissues in response to hormone stimulation and are localized in the mitochondria of these tissues. In an attempt to determine whether these induced proteins may be involved in steroidogenesis, we compared mitochondrial protein profiles in two separate Leydig tumor cell line. One cell line, the MA-10 mouse Leydig tumor cell line, has a very low basal steroid production, but synthesizes large amounts of progesterone in response to both tropic hormone and cAMP analog. The other cell line, the R2C rat Leydig tumor cell line, produces constitutively large amounts of progesterone, which cannot be increased further with hormone stimulation. Two-dimensional polyacrylamide gel electrophoresis profiles of newly synthesized mitochondrial proteins demonstrated that four 30-kDa proteins are induced in response to hormonal stimulation in MA-10 cells. Further, it was shown that proteins identical to these induced proteins are present constitutively in the mitochondria of R2C cells and cannot be further increased with hormone stimulation. These results strongly suggest that the 30-kDa mitochondrial proteins shown to be induced in several steroidogenic tissues are involved in the acute regulation of steroid production.

Animals↗
PubMed1991

An epidemiological study of lung cancer in Xuan Wei County, China: current progress. Case-control study on lung cancer and cooking fuel.

In Xuan Wei County, Yunnan Province, lung cancer mortality rates are among China's highest in males and females. Previous studies have shown a strong association of lung cancer mortality with air pollution from "smoky" coal combustion. In the present quantitative risk assessment of indoor air pollution study, the result strongly shows an obvious on-site exposure-response relationship between benzo[a]pyrene concentration in indoor air and lung cancer mortality and strongly supports the hypothesis that indoor air pollution is the main risk factor in inducing lung cancer in Xuan Wei County. In the present case-control study, the result shows that in females, the presence of lung cancer is statistically significantly associated with chronic bronchitis and family history of lung cancer. The results also suggest an association of lung cancer with duration of cooking food, but not with passive smoking. In males, the presence of lung cancer is associated with smoking, bronchitis, family history of lung cancer, and personal history of cooking food.

Air Pollution, Indoor↗
PubMed1991

Different binding of stimulatory-type and blocking-type TSH receptor antibody with guinea-pig testis membrane.

A receptor assay using [125I]bTSH-binding to guinea-pig testis membrane was developed. Unlabelled hCG and FSH inhibited [125I]bTSH binding. In patients with Graves' disease and in untreated hyperthyroid patients, almost all long-acting thyroid stimulators and thyroid-stimulating antibodies, respectively did not inhibit [125I]bTSH binding, which on the other hand was inhibited by thyroid stimulation blocking antibodies in patients with primary hypothyroidism. When the inhibitory effect on the binding of [125I]hCG and 125I-synthetic alpha-subunit peptide (alpha 26-46) of hCG to testis membrane was examined, bTSH resulted in a significant inhibition. However, all three kinds of TSH receptor antibodies had no inhibitory effect. This study demonstrated 1. interaction of alpha-subunit of TSH and hCG with the testicular receptor; 2. binding of thyroid stimulation-blocking antibody and lack of binding of thyroid-stimulating antibody to the testicular TSH receptor in spite of binding of these TSH receptor antibodies to the thyroidal TSH receptor, and 3. lack of binding of thyroid-stimulating antibody and thyroid stimulation-blocking antibody to the testicular gonadotropin receptor.

Amino Acid Sequence↗
PubMed1991

Protective effect of zinc-induced metallothionein synthesis on gentamicin nephrotoxicity in rats.

Wistar rats were used to study the protective effect of zinc-induced metallothionein (MT) synthesis on gentamicin nephrotoxicity. We found that s.c. pre-injection of ZnSO4 (Zn 10 mg/kg/day) for 5 days could ameliorate proximal tubular necrosis and acute renal failure caused by an 8-day s.c. injection of gentamicin (100 mg/kg/day), while preinjection of saline instead of zinc or zinc and gentamicin together could not. In the zinc-pretreated rats (n = 6), renal cortical metallothionein level was significantly higher than that of normal (n = 8, p less than 0.001) and the saline controls (n = 6, p less than 0.001). Since MT is a scavenger of hydroxyl radical, it is proposed that hydroxyl radical plays a role in the pathogenesis of gentamicin nephrotoxicity and that preinjection of zinc could ameliorate gentamicin nephrotoxicity via the induction of renal cortical MT synthesis.

Acute Kidney Injury↗
PubMed1991

[Homology of Chinese, Japanese, and American strains of hepatitis C virus].

As we know, the main HCV strain in Japan (HCV-J 4) is highly diverse in sequence from the original American strain (HCV-US). By comparing the sequences of these two strains, a region, located in the 3'-terminus of the putative E gene in HCV genome, was selected for PCR amplification. In this region, the Japanese strain showed high diversity from the American strain. From 4 patients, 8 isolates with the length of 277 bp, were cloned and sequenced. The homology of these 8 clones was high, indicating that these clones were in the same strain. This strain might be the major strain in China, named HCV-CHN1 in this paper. Since there were still many varieties in these 8 clones, HCV CHN1 could be possibly divided into 3 substrains. HCV-CHN1 was also found to be similar to HCV-J 4, with nucleotide homology of 83.4-86.3%, and amino acid homology of 78.3-88.0%, but remote from HCV-US, with homologies of only 68.6-72.6% and 69.6-73.9%, respectively. These results might be of paramount significance in developing the detection method for HCV infection and in preparing HCV vaccine.

Amino Acid Sequence↗
PubMed1991

Serum zinc and copper during long-term total parenteral nutrition.

Changes in serum zinc and copper levels were studied in 17 patients who received 18 courses of total parenteral nutrition for 28 to 89 days. Mean serum zinc levels decreased significantly after 4 weeks of therapy in the group without zinc supplementation when compared with pretreatment levels (p less than 0.05) and in a second group who received about 1.5 mg of zinc per day (p less than 0.05). Serum copper levels fell consistently and significantly in patients of both groups. However, no obvious clinical signs or symptoms of zinc or copper deficiencies were observed. Blood transfusions were not able to significantly change the serum levels of zinc or copper. Although serum alkaline phosphatase has been suggested as a functional indicator of zinc deficiency, the concomitant hepatic or skeletal dysfunction of the patients made its interpretation difficult. These findings indicate that a decrease in serum zinc and copper is common during TPN using solutions unsupplemented with these trace elements. Supplementation of TPN solutions with zinc, copper, and other trace elements is recommended.

Adult↗
PubMed1991

Morphological and morphometric studies of the airways of sheep with acute airway hypersensitivity to inhaled Ascaris suum.

The airways of 12 sheep with naturally-occurring allergic airway hypersensitivity, six of which had changes in both airway resistance and dynamic lung compliance (Group A) and six of which had changes in only dynamic lung compliance (Group B), were compared quantitatively with six non-reacting sheep (Group C) in order to examine the relation between airway hypersensitivity and various morphological features thought to be related to airway hypersensitivity. Compared to the non-reacting sheep (Group C), the hypersensitive sheep (Groups A and B) had a thinner epithelium in medium bronchi and bronchioles, fewer goblet cells in bronchioles, and greater gland area at most airway levels. The differences of the gland dimensions and the types of mucosubstance between hypersensitive and non-reacting animals were more variable. No significant differences between the three groups were noted with regard to luminal occlusion or epithelial sloughing and squamous metaplasia. Although there was a positive association between epithelial thickness and goblet cell density in the small airways, the development of allergic airway hypersensitivity in sheep may occur in the absence of major morphological changes in the airway epithelium.

Animals↗
PubMed1991

Stochastic simulation algorithms for query networks.

One of the barriers to using belief networks for medical information retrieval is the computational cost of reasoning as the networks become large. Stochastic simulation algorithms allow one to compute approximations of probability values in a reasonable amount of time. We previously examined the performance of five stochastic simulation algorithms applied to four simple belief networks networks and found that the Self-Importance algorithm performed well. In this paper, we examine how the same five algorithms perform when applied to a belief network derived from the cardiovascular subtree of the Medical Subject Headings (MeSH). Both the Likelihood Weighting and Self-Importance algorithms perform well when applied to the MeSH-derived network, suggesting that stochastic simulation algorithms may provide reasonable performance in medical information retrieval settings.

Algorithms↗
PubMed1991

[Construction of Echinococcus granulosus genomic library].

Using EMBL3 phage DNA as a vector, a perfect genomic library of Echinococcus granulosus from sheep from Xinjiang has been constructed, which contains 1.2 x 10(6) independent recombinants. The main procedure of construction comprised: 1. extraction of Echinococcus granulosus genomic DNA, 2. partial digestion of the extracted E. granulosus genomic DNA with restriction enzyme Sau3Al, 3. harvest of 15-23 kb DNA fragments by electric elution equipment, 4. preparation of EMBL3 phage vector DNA, 5. cleavage of EMBL3 vector DNA with two restriction enzymes Bam HI and Eco RI to remove the central fragment, 6. ligation of the harvested 15-23 kb E. granulosus genomic DNA and the cleavaged vector DNA with T4 DNA ligase, 7. the package reaction of ligated recombinant DNA in vitro with the package protein and with Q359 strain (Spi-) to screen recombinants, 8. identification of the genomic library, 9. hybridization in situ by pSM889 probe, obtaining 6 positive recombinant clones. It was estimated that the E. granulosus genome was about 1.5 x 10(8) bp. A perfect E.g. genomic library is expected to contain 4.6 x 10(4) independent recombinants at minimum. The constructed genomic library has enough independent recombinants (1.2 x 10(6)). This is the first time to establish an E. granulosus genomic library in China. Previous work showed that there existed differences in many aspects, including pathogenicity, among various isolates of E. granulosus from different hosts and areas. We plan to employ this library to screen the E. granulosus intraspecies DNA probe by hybridization in situ. This kind of probe is envisaged to be of advantage for epidemiological investigation of the hydatid disease in China. It also provides a base for researching E. granulosus at the molecular level.

Animals↗
PubMed1991

[Analysing the effects of tooth extraction under acupuncture anesthesia in 825 cases of senior].

It has been found that the effects of tooth extraction under acupuncture anesthesia (AA) for the old patients are generally quite good. In order to verify this result, the authors had statistically analysed 825 cases aged over 60 years (Group A) and equal quantity whose age were between 18-40 years old (Group B) out of more than 4000 cases whose records of AA were rather completely during 1973 to 1988. 1. There was no significant difference under AA for different sexes. 2. The differences of the excellent rate of AA between Group A and Group B were extremely evident either in the positions of the tooth or the reason of tooth extraction. The former was 89.04% and the latter 76.20% (P less than 0.005). 3. Although a low rate in excellence of tooth extraction under simple AA (only 75.58%), not so good as the effect by AAA (an average about 88.21%), the simple AA was more common and more easier to be accepted by patients. 4. Tooth extraction under AA has been proved to be safe, effective and without any complications. 5. The reasons for the senior to extract their teeth were almost for the broken crowns and of roots or the purposes of prosthetic restoration. Even though the pain thresholds in the senior were commonly higher. It is still an important factor of the good effect and good rate of tooth extraction under AA. Referring to the statistics in this study the authors suggest that the hospitals which can use the AA for tooth extraction adopt the method as the first choice of anesthesia method to the senior who intends to accept it.

Acupuncture Analgesia↗
PubMed1991

[A study on serum suppressive factor(s) on lymphocyte proliferation in rats under restraint stress].

In order to study the effect of stress on lymphocyte proliferation, SD rats were restrained with four limbs tied on a frame in supine position at room temperature (20 degrees C) for 20 h, and control animals were not disturbed in home cage. The blood was then collected from the heart under light ether anesthesia. The peripheral blood lymphocytes were separated from heparinized whole blood by density gradient (d 1.077) centrifugation, or the serum was obtained after the blood coagulated at 4 degrees C for about 6h. It was found that the blood lymphocyte proliferation induced by Con A was significantly inhibited in the stressed group as compared with the control (P less than 0.01, n = 8, ANOVA). The result was in accordance with our earlier study in which the animals were stressed with electric shock. In the present study, it was also found that the serum of the stressed animals was capable of suppressing Con A-induced lymphocyte proliferation of normal mice (P less than 0.01, n = 8, ANOVA) to a significant extent. Thus the present experiment suggests that there is some substance with suppressive activity on lymphocyte proliferation in the serum of the stressed rats. The serum lost its suppressive activity when it was heated to 100 degrees C (3 min), treated with 60% methanol or incubated with trypsin (64 micrograms/ml), thus suggesting that the suppressive factor(s) most likely is a kind of protein.

Animals↗
PubMed1991

Versatile, non-clotting-based heparin assay requiring no instrumentation.

A non-clotting-based heparin assay requiring no instrumentation has been developed by attaching protamine (a heparin antidote) to a porous filter paper strip and monitoring the subsequent capillary migration of heparin sample through the paper. The area of paper to which heparin adsorbed, which is proportional to the concentration of heparin in the sample, is made visible by spraying Methylene Blue NNX solution onto the paper strip when the sample reservoir has emptied. The dye interacts with heparin to cause a metachromatic shift of the dye's absorption maximum from blue to purple. Heparin concentrations in the samples are estimated according to the length of the purple region on the paper strip. Heparin in plasma (2 to 35 int. units/mL) can be differentiated in approximately 6 min. The plasma heparin values derived by the new method agree reasonably well with those obtained by conventional assays (r greater than 0.99, n = 48).

Extracorporeal Circulation↗
PubMed1990

Adoptively transferred antigen-specific T cells can be grown and maintained in large numbers in vivo for extended periods of time by intermittent restimulation with specific antigen plus IL-2.

The aim of the current study was to determine whether cultured tumor Ag-specific T cells could be induced to grow and maintained functional in large numbers in vivo by intermittent restimulation in vivo with specific Ag plus IL-2. T cells derived from spleens of B6 mice (Thy-1.2) immune to FBL-3, a Friend virus-induced leukemia, were activated by in vitro stimulation with irradiated FBL-3 and expanded by culture for 14 days with low concentrations of IL-2. The resultant FBL-3-specific T cell lines were adoptively transferred into cyclophosphamide pretreated congenic hosts (B6/Thy-1.1), and restimulated every 14 days by an injection of irradiated FBL-3 plus a 7-day course of IL-2. Donor T cells residing in the host were identified and quantified by use of antibody to the Thy-1.2 allele. The results confirmed that stimulation with FBL-3 on the day of transfer (day 0) plus IL-2 on days 0 to 6 induced rapid growth of donor T cells to approximately an 11-fold increase in total donor T cell number recoverable from host ascites and spleen by day 7. However, prolonging the course of IL-2 administration to 35 days did not maintain the number or the specific cytolytic function of donor T cells. By contrast, intermittent restimulation with specific Ag plus IL-2 induced intermittent regrowth of donor T cells in vivo, maintained the number of donor T cells in vivo at greater than the number input for longer than 1 mo, and allowed detection of substantially augmented donor T cell-mediated specific antitumor function over that period of time.

Animals↗