Fine-structure energies for the 1s2s 3S-1s2p 3P transition in heliumlike Ar16+
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
S Cheng
Publications and source records attributed to S Cheng.
[Modifications of gene expression by tumor promoters].
The modifications of gene expression by tumor promoters were analyzed in vitro and in vivo. The results of slot blot hybridizations showed that tumor promoter TPA induced c-fos and c-myc expressions in mouse fibroblast cell line BALB/3T3 and rat liver, decreased the levels of Rb RNA in BALB/3T3 cell line and of alpha 1-I3 RNA in rat liver. It was also demonstrated that tumor promoter phenobarbital influenced c-fos and c-myc expressions and decreased alpha 1I3 mRNA level in rat liver during a long term experiment. Phenobarbital was found to have no effect on c-fos and c-myc expressions in rat liver during a short experiment. Tumor promoters induced the expressions of c-fos and c-myc which were positively-related to cancer formation and inhibited the expressions of Rb and alpha 1-I3 which were negatively-related to cancer formation. This implied that tumor promotion played an important role in cancer development and tumor promoters exerted their effects selectively according to the attributes of different genes.
3T3 Cells↗
[14C-urea breath test in the diagnosis of Helicobacter pylori infection in the stomach].
We developed a modified 14C-urea breath test (14C-UBT) to diagnose Helicobacter pylori (Hp) infection in 70 patients in which subjects were given 92.5 kBq (2.5 microCi) 14C-urea with 25 mg nonradioactive urea, without nutrient-dense meal. Using the mean value +3s as a cutoff value, the 20 min sample gave a sensitivity of 97.36%, a specificity of 90.00%, a positive predictive value of 97.36%, and a negative predictive value of 90.0%. Our data showed: (1) A satisfying accuracy of the modified 14C-UBT for the detection of Hp infection was obtained. (2) Taking 92.5 kBq (2.5 microCi) 14C-urea and 20 min collected sample may be of great use and to replace the previous big dose and long time methods. (3) This test may be applied routinely as a noninvasive, accurate, low cost, safe and rapid method. (4) It played an important role in reflecting the susceptibility of Hp to various drugs in vivo and monitoring the recurence of Hp.
Adult↗
[Metallothionein and medicine].
Metallothioneins are attractive substances. One of the features of these proteins is the inducibility in response to heavy metals, to a great variety of metabolites and to stress factors. In mammalia, their synthesis may be induced by interleukin-6 in response to inflammation. Metallothionein could prevent renal toxicity of cDDP without compromising its anticancer activity. However, metallothionein is also implicated in the resistance to cDDP. There are now good evidences that metallothionein is involved in many diseases, such as inflammatory bowel disease, toxemia of pregnancy, liver disease, etc.
Animals↗
[Protective effect of semen Ziziphi spinosae on superoxide dismutase reduction in mice with endotoxin fever].
An animal model with decreasing SOD was established by fever from intravenous injection of endotoxin. The SOD level was measured by RIA in the animal serum and liver tissues. The results indicated that the SOD level of the model group was obviously lower than that of the normal group (P < 0.05), but the level of the group treated with Semen Ziziphi Spinosae was higher than that of the model group. The study shows that Semen Ziziphi Spinosae can protect mice with endotoxin fever from SOD decrease.
Animals↗
[Detection of c-myc translocation in human lung cancer cells by fluorescence in situ hybridization (FISH)].
c-myc gene amplification has been found in lung cancer, however, it can not explain all cases of lung cancer with c-myc gene overexpression. Gene translocation is one of the ways by which oncogene is activated. But the old methods for detecting gene mutations are not so effective for the detection of gene translocation, especially in solid tumors. Fluorescence in situ hybridization (FISH) can be used to detect gene translocation more efficiently. Using FISH, we discovered c-myc gene translocation in a lung adenocarcinoma cell line GLC-82 and SV40T-transformed human bronchial epithelial cells. In GLC-82, c-myc gene translocated to the short arm of a C group marker chromosome. In the SV40T-transformed epithelial cells, c-myc gene translocated to 14q32, which was the same as that found in Burkitt's lymphomas. Translocation was related to oncogene activation. c-myc translocation may play an important role in the carcinogenesis of lung cancer.
Adenocarcinoma↗
[Establishment of a new culture system for fetal human tracheobronchus].
Human tracheobronchial tissues were cultured in CMRL 1066 medium containing insulin, hydrocortisone, bovine pituitary extract, and trace elements, with or without fetal bovine serum, in a rocked atmosphere chamber. The morphology of the epithelium remained normal for two months after in organ culture, and then, squamous metaplasia appeared in the epithelium and maintained for more than one year. There were continuous epithelial outgrowths from the human tracheobronchial tissues during the whole duration of organ culture, and the epithelial outgrowth can be subcultured in MCDB 151 medium supplemented with growth factors and grew as a tightly packed monolayer of polygonal cells with the presence of keratin and microvilli. The advantages of organ culture and epithelial cell culture were combined in this new culture system. The new culture model has already been used for the investigation of in vitro transformation of human tracheobronchial epithelial cells by chemical carcinogens in our laboratory.
Bronchi↗
[Manufacture of computer-based testing and analyzing system for measuring step-through performance].
The computer-Based Testing and Analysing System for measuring Step-Through (avoiding darkness) performance (CTASS) has been developed. The system is based on the infrared beams which transfer actions of mice inside the boxes into signals of voltage. The signals are fed into the computer through A/D converter to computer for software processing. The functions which have been realized include, but not limited to: signal sampling and data curve displaying; intelligent identification and elimination of jamming signal; auto-calculation of number of errors (No) in all channels, latent period (LP) of entering into the light chamber, total time of mice staying in the light chamber (safty place Tl) and dark chamber (error place Td); hardcopy of screen graphics and resulting output by various printers. The CATSS system was applied to test normal mice and the cognition-deficient mice induced by anisodine, a M-Cholinergic antagonist at a dose of 1-10 mg/kg i.p. The data collected by the system were compared and proved to be consistent with those acquired by manual labour. The system has produced refined and accurate information refined to a maximum extent and guaranteed scientifically sound experimental results. It is foreseable that introducing the computer into pharmacological researches will update and advance their methodology.
Animals↗
Synergistic insertion of two hydrophobic regions drives Sec-independent membrane protein assembly.
We have studied the membrane insertion of two proteins from the inner membrane of Escherichia coli, both with two transmembrane segments connected by a short periplasmic loop: the M13 procoat protein and a mutant "inverted" leader peptidase. Neither molecule depends on the Sec machinery for insertion. We show that the introduction of a charged residue in the second transmembrane segment completely blocks insertion of both proteins. In contrast, a Sec-dependent procoat mutant, where the periplasmic region has been lengthened, inserts into the membrane even in the presence of a charged residue in the second hydrophobic domain. In addition, a large deletion within the second transmembrane domain of the leader peptidase mutant allows membrane translocation, but only under conditions where the SecA protein is functional. Furthermore, we show that the first hydrophobic domain is required for insertion of the short periplasmic loop of the "inverted" leader peptidase. These results suggest that Sec-independent insertion occurs by a synergistic entry of the two neighboring hydrophobic domains into the lipid bilayer.
Bacterial Proteins↗
Ionization and multifragmentation of C60 by high-energy, highly charged Xe ions.
Explore the source record for details and available documents.
Journal Article↗
Effective amplification of long targets from cloned inserts and human genomic DNA.
We have used the polymerase chain reaction (PCR) to amplify up to 22 kb of the beta-globin gene cluster from human genomic DNA and up to 42 kb from phaga lambda DNA. We have also amplified 91 human genomic inserts of 9-23 kb directly from recombinant lambda plaques. To do this, we increased pH, added glycerol and dimethyl sulfoxide, decreased denaturation times, increased extension times, and used a secondary thermostable DNA polymerase that possesses a 3'-to 5'-exonuclease, or "proofreading," activity. Our "long PCR" protocols maintain the specificity required for targets in genomic DNA by using lower levels of polymerase and temperature and salt conditions for specific primer annealing. The ability to amplify DNA sequences of 10-40 kb will bring the speed and simplicity of PCR to genomic mapping and sequencing and facilitate studies in molecular genetics.
Bacteriophage lambda↗
Experimental studies of the inhibitory effects of green tea catechin on mice large intestinal cancers induced by 1,2-dimethylhydrazine.
Three hundred Kunming mice were randomly divided into six groups (half males and half females in each group). Group 1 was the positive control group, Groups 2, 3, 4 and 5 were experimental groups and Group 6 was used as the solvent control group. Mice in Groups 1-4 were injected with 1,2-dimethylhydrazine (1,2-DMH) (20 mg/kg body wt.) solution subcutaneously once a week from the 2nd week to the 20th week. From the 1st week to the 23rd week, mice in Groups 2, 3 and 4 were given catechin (1 mg/mouse), catechin (2 mg/mouse) and EGCG (2 mg/mouse), respectively, five times a week. Mice in Group 5 received only catechin (3 mg/mouse) five times a week from the 1st to the 23rd week. Mice in Group 6 were injected with an equal volume of 1 mmol EDTA solution subcutaneously once a week from the 2nd to the 20th week. At the end of the 27th week, all the mice were killed by cervical dislocation (Zhu, Q.H. and Zhu, Q.F. (1991) Laboratory Animal Science, 1st edition. The Junior Educational Publisher, Guangdong). Pathological examinations indicated that the incidence of large intestinal cancers occurring in Group 1 was 80%, significantly higher than that in Groups 2, 3 and 4 (p < 0.001). No tumors were found in Groups 5 and 6. This might suggest that green tea has preventive effects on large intestinal cancer induction in spite of the different doses of catechin. Immunohistochemistry studies showed that green tea catechins could enhance the activity of superoxide dismutase (SOD) in tissues.
1,2-Dimethylhydrazine↗
A controlled study of ranitidine for the prevention of recurrent hemorrhage from duodenal ulcer.
BACKGROUND: Hemorrhage is the most common complication of duodenal ulcer disease, but there is little information about the effectiveness and safety of long-term maintenance therapy with histamine H2-receptor blockers. METHODS: We conducted a double-blind study in patients with endoscopically documented hemorrhage from duodenal ulcers. Patients were randomly assigned to maintenance therapy with ranitidine (150 mg at night) or placebo and were followed for up to three years. Endoscopy was performed at base line (to document that the ulcers had healed), at exit from the study, and when a patient had persistent ulcer symptoms unrelieved by antacids or had gastrointestinal bleeding. Symptomatic relapses without bleeding were treated with ranitidine; if the ulcer healed within eight weeks, the patient resumed taking the assigned study medication. RESULTS: The two groups were similar at entry, which usually occurred about three months after the index hemorrhage. After a mean follow-up of 61 weeks, 3 of the 32 patients treated with ranitidine had recurrent hemorrhage, as compared with 12 of the 33 given placebo (P < 0.05). Half the episodes of recurrent bleeding were asymptomatic. One patient in the ranitidine group withdrew from the study because of asymptomatic thrombocytopenia during the first month. CONCLUSIONS: For patients whose duodenal ulcers heal after severe hemorrhage, long-term maintenance therapy with ranitidine is safe and reduces the risk of recurrent bleeding.
Double-Blind Method↗
Design and synthesis of novel cyclic RGD-containing peptides as highly potent and selective integrin alpha IIb beta 3 antagonists.
Utilizing conformational constraints in conjunction with various structural considerations, we have synthesized a series of cyclic disulfide peptides that are highly potent and selective antagonists for the platelet integrin alpha IIb beta 3 (GPIIb/IIIa). The affinities of the peptides for alpha IIb beta 3 were determined by platelet aggregation assays and an alpha IIb beta 3 ELISA. Their affinities for alpha 5 beta 1 and alpha v beta 5 integrins were also determined in respective ELISA assays. Structure-activity relationship studies suggest that R-G-D-Ar-R (Ar = hydrophobic residue) is the essential pharmacophore that is responsible for their high alpha IIb beta 3 binding affinity, very high selectivity, and distinct biological properties. One of these analogues, TP9201, has been shown to inhibit platelet-mediated thrombus formation without associated prolongation of template bleeding time. The arginine residue adjacent the carboxy terminus of the R-G-D-Ar sequence could function as the biological effector element that determines this distinct and unexpected biological property.
Amino Acid Sequence↗
YAC clones targeting gene-rich regions of human chromosome 3.
Explore the source record for details and available documents.
Chromosome Mapping↗
Bone density of the calcaneus and fractures in 75- and 80-year-old men and women.
Bone mineral density of the calcaneus in relation to fractures was studied both retrospectively and prospectively among the 75- and 80-year-old men and women resident in the city of Jyväskylä, Finland, in 1989 and 1990, respectively. The bone measurements were performed at the calcaneus by 125I-photon absorption. Retrospective fracture (RF) history after age 50 was collected by questionnaire and interview, and reported fractures were checked from medical records. In the retrospective study, in the 75-year-olds a fracture was found in 22% (n = 22) of men and in 45% (n = 84) of women. The corresponding figures for the 80-year-olds were 16% (n = 9) and 35% (n = 48). Over half of the fractures were of the wrist/hand or ankle/leg. Prospective fractures (PF) were recorded over periods of 29-34 months. Twenty of the 75-year-olds and 16 of the 80-year-olds sustained a fracture during the follow-up period. In the 75-year-olds, the results showed that both RF and PF women, together with the RF men, had lower bone area density (BMDa) and volume density (BMDv) than the non-fracture (NF) subjects (p = 0.001-0.011). In the 80-year-olds, significantly lower BMDa was found in the RF women (p = 0.008) and lower BMDv in the PF women (p = 0.024) compared with the NF subjects. During the follow-up period there were no fractures in either of the sex or age groups among those with BMDa and BMDv values greater than 1 SD above the mean. (ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Complete mitochondrial genome amplification.
Explore the source record for details and available documents.
B-Lymphocytes↗