Biomedical subjects
Publications and source records attributed to R Yan.
The genomic structure of Stat2 has been determined and compared with a large portion of the Stat1 gene. There are 24 exons in the Stat2 gene and a matching number in very similar positions in the Stat1 gene. Thus a very complicated genomic structure was presumably duplicated and has been closely maintained throughout evolution.
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UNLABELLED: Gastroscopic and gastric juice analysis studies were carried out on 12 patients with total body surface area over 30 percent who received early enteral feeding, supplemented with glutamine. The results indicated that early feeding was safe in major burn patients. All patients were found to have ASML on postburn days 1 to 2. Stress ulcer was not found in patients after several excision operations, and about 86 percent of ASML disappeared within about 2 weeks. CONCLUSION: early feeding and supplement of glutamine can prevent the complication of stress ulcer following severe thermal injury.
The rate of protein synthesis is controlled in a large number of physiological situations at the stage of 48 S initiation complex formation, a phase that involves the recruitment of mRNA to the 40 S ribosomal subunit. This process is mediated by the eukaryotic initiation factor-4 (eIF-4) group of translation initiation factors consisting of eIF-4E, eIF-4A, eIF-4B, and eIF-4 gamma. In order to develop a new tool to study this process, we have produced radiolabeled eIF-4 gamma by in vitro transcription and translation. Despite the fact that eIF-4 gamma is predicted from the cDNA sequence to be 154 kDa, the major synthetic product migrated on SDS-polyacrylamide gel electrophoresis at 205 kDa. Although this is similar to the migration of the fastest polypeptide of authentic eIF-4 gamma (approximately 206 kDa), no products were found to co-migrate with the slowest forms of authentic eIF-4 gamma (210-220 kDa), suggesting that these forms derive from extensive modification of the initial polypeptide. The in vitro product also formed a complex with eIF-4E, as judged by its ability to bind to m7GTP-Sepharose. Sucrose gradient sedimentation studies demonstrated that eIF-4 gamma was present on both 43 and 48 S initiation complexes but not 80 S complexes. This supports a model in which free eIF-4E binds to mRNA followed by binding of the eIF-4E.mRNA complex to a 43 S initiation complex already containing eIF-4 gamma.
Total RNA of Leptospira interrogans SV Lai strain 017 was prepared by the method of Licl-Urea, and was used in dot hybridization with biotin-labelled DNA probes. The probes included BMD-3A, BMD-10, which were the leptospirial protective antigen genes, and CPL 5x, which was the genus specific gene of interrogans Leptospira. All of the three probes have shown various degrees of hybridization signs, proving that they all have transcript expression in leptospira. The transcript expression is the main way of regulating the gene expression in procaryotae, and it is significant in molecular genetics of Leptospira. The results indicate that the antigens encoded by the BMD-3A, BMD-10 may play an important role in immune reaction against leptospiral infection and provide a clue to the development of gene-engineering vaccine. The results also suggest that the antibody against the antigen encoded by CPL 5x is a useful tool in the classification of Leptospira interrogans.
The functional differentiations of stomach cancer specimens from 121 patients were investigated by enzyme-, mucin-, affinity- and immunohistochemical methods, and the stomach cancers were divided into five functionally differentiated types: 1) Absorptive Function Differentiation Type (AFDT), 19.8%; 2) Mucin Secreting Function Differentiation Type (MSFDT), 24.0%; 3) Absorptive and Mucin-Producing Function Differentiation Type (AMPFDT), 47.1%; 4) Special Function Differentiation Type (SFDT), 0.8%; and 5) Non-Function Differentiation Type (NFDT), 8.3%. The results indicate that stomach cancer tissues of the same histological type often display differing functional differentiation, and these functionally differentiated types have different invasive and metastatic characteristics. In addition, the functionally differentiated types have particular organic affinities of metastasis and different clinical prognoses. This study suggests that this new functional classification may supplement histological classification. The mechanisms of liver and ovary metastases of stomach cancer are also discussed.
Since "Mei Bao" has been used in clinical treatment of burn wounds, there is a diversity of opinions concerning its effect. We carried out a series of experiments to observe its therapeutic effect, bacteriostatic property, and its effect on production of IL-2 in thermally injured rats. These results indicate that obvious infection occurred after its use on burn wounds and healing is delayed. Hyperplastic scars accompanying with deformity appeared after healing. The cost of treatment is high. There is no improvement in immune reaction, and no bacteriostatic property is observed.
The rate-limiting step of eukaryotic protein synthesis is the binding of mRNA to the 40 S ribosomal subunit, a step which is catalyzed by initiation factors of the eIF-4 (eukaryotic initiation factor 4) group: eIF-4A, eIF-4B, eIF-4E, and eIF-4 gamma. Infection of cells with picornaviruses of the rhino- and enterovirus groups causes a shut-off in translation of cellular mRNAs but permits viral RNA translation to proceed. This change in translational specificity is thought to be mediated by proteolytic cleavage of eIF-4 gamma, which is catalyzed, directly or indirectly, by the picornaviral 2A protease. In this report we have used highly purified recombinant 2A protease from either human Coxsackievirus serotype B4 or rhinovirus serotype 2 to cleave eIF-4 gamma in vitro in the eIF-4 complex purified from rabbit reticulocytes. Neither the rate of cleavage nor fragment sizes were affected by addition of eIF-3. The NH2- and COOH-terminal fragments of eIF-4 gamma were separated by reverse phase HPLC and identified with specific antibodies, and the NH2-terminal sequence of the COOH-terminal fragment was determined by automated Edman degradation. The cleavage site for both proteases is 479GRPALSSR decreases GPPRGGPG494 in rabbit eIF-4 gamma, corresponding to 478GRTTLSTR decreases GPPRGGPG493 in human eIF-4 gamma.
A mammalian cell infected with a human rhinovirus or enterovirus has a much reduced capability to translate capped mRNAs (the host cell shutoff), while still allowing translation of uncapped viral RNA. Biochemical and genetic evidence suggests that the viral proteinase 2A induces cleavage of the eukaryotic initiation factor (eIF) 4 gamma (also known as p220) component of eIF-4 (formerly called eIF-4F). However, neither the mechanism underlying the specific proteolysis of eIF-4 gamma nor the influence of this cleavage on the translation of capped mRNAs has been clarified. Such studies have been hampered by a lack of large quantities of a purified 2A proteinase. Therefore, the mature proteinases 2A of human rhinovirus 2 and coxsackievirus B4 were expressed in soluble form in Escherichia coli. A four-step purification protocol was developed; 1 mg of highly purified 2A proteinase per gram wet weight of E. coli was obtained. Both enzymes cleaved directly eIF-4 gamma as part of the purified eIF-4 complex. Addition of HRV2 2A proteinase to HeLa cell cytoplasmic translation extracts resulted in eIF-4 gamma cleavage and drastically reduced the translation of capped mRNA; addition of purified eIF-4 restored translation to the initial level. However, translation of a reporter gene driven by the 5'-untranslated region of human rhinovirus 2 was translated 2-3-fold more efficiently in the presence of HRV2 2A proteinase.
Preparation of yuanhuacine by low pressure column chromatography gives high separation rate, short washing time and one time crystallization, which comes up to the standard published by the Ministry of Public Health. The method is simple and convenient.
Eukaryotic protein synthesis initiation factor (eIF) 4 gamma, also known as p220, is a component of the protein complex eIF-4, which is involved in the recognition of the mRNA cap, ATP-dependent unwinding of 5'-terminal secondary structure and recruitment of mRNA to the ribosome. Peptide sequence data from rabbit reticulocyte eIF-4 gamma was used to synthesize oligonucleotide probes and polymerase chain reaction primers. These were used to screen lambda-cDNA libraries from rabbit and human brain, yielding a partial rabbit and a complete human cDNA sequence of 5.1 kilobases. Northern blot and primer extension analysis indicated that the cDNA sequence was complete. To confirm that the cDNA represented that of eIF-4 gamma, three peptides were synthesized based on cDNA sequences and used to produce anti-peptide antibodies. The antibodies specifically recognized intact eIF-4 gamma and its cleavage products following poliovirus infection. The eIF-4 gamma mRNA contains AUG codons at nucleotides 6, 67, 90, 165, and 369, but only the last is followed by a long open reading frame. The eIF-4 gamma polypeptide is 154 kDa (1396 amino acid residues) and contains sequence motifs of potential interest: a sequence (AGLGPR) that is similar to the substrate recognition sequence of protease 2A from rhinovirus serotype 14, five PEST regions with scores greater than 10, which are characteristic of rapidly degraded proteins, stretches of polyglutamic acid, and numerous potential phosphorylation sites.
Preparative regimens for bone marrow transplantation (BMT) use a sequence of drugs, such as cyclophosphamide, in combination with radiation. However, the optimum sequencing of the two agents that will maximize tumor cell kill and minimize normal tissue damage is unknown and controversial. The studies presented here were done in order to determine the effect of cyclophosphamide on bone marrow and lung damage in mice when given 24 h before or after total body irradiation (TBI). A range of single doses of TBI was given before or after a single sublethal dose of 180 mg/kg of cyclophosphamide. The bone marrow of all mice intended for lung damage assessment was reconstituted with 5 x 10(6) syngeneic bone marrow cells. Lung damage was assessed by breathing rate and lethality; bone marrow damage by lethality at 30 days. LD50 values for pneumonitis were obtained between 30 and 84 days after cyclophosphamide and radiation and between 80 and 180 days after radiation alone. Dose modifying factors were obtained as the ratio of LD50s for mice given only TBI compared to those for mice given cyclophosphamide and TBI. Cyclophosphamide enhanced radiation pneumonitis when given before or after TBI, giving DMFs of 1.4 and 1.2 (1.1-1.4, 95% c.l.) respectively. The effect of cyclophosphamide on radiation pneumonitis was drug dose-dependent. The LD50 for death from bone marrow damage was reduced when cyclophosphamide was given either before or after TBI but the effect was greater, i.e. the LD50 was lower when cyclophosphamide was given after TBI. These data show that cyclophosphamide given 24 h after TBI causes less lung damage but more bone marrow damage in this mouse model.
"In order to make up for the incompleteness of data in the last 40 years, this paper will try to make a preliminary study of the age-specific mortality rate and average life expectancy and its changing trends [for] the Chinese population over the last 40 years, based on the relevant data on mortality from sample surveys on fertility and birth control among Chinese women."
The fusion of peripheral B lymphocytes from human immunized with P. aeruginosa polyvalent vaccine and mouse myeloma cell line SP2/0 was successfully performed. The rate of fusion was 74%(71/96) and the positive rate of antibody was 19.7%. Two hybridoma cell lines (A3 and F8) secreting McAb against P. aeruginosa were obtained after three times cloning by limiting dilution. The human chromosomes together with mouse chromosomes were discovered in karyotype assay of the hybrids. A3 and F8McAbs were human IgG by class determination. These MrcAbs could recognize 43 kd and 36 kd MW specific components of P. aeruginosa antigen by enzyme linked immuno-transfer blot technique.
BALB/c mice were immunized intraperitoneally with outer envelopes of serogroup icterohaemorrhagiae lai serovar strain 017 leptospires. Monoclonal antibodies against outer envelopes (IgG, agglutinating titre 1:25,600) were produced by hybridoma technique. The monoclonal antibodies ascites (diluted 1:100) 1 ml administered intraperitoneally 1 hour before the intraperitoneal injection of 2 x 10(8) leptospires of strain 017 and the subsequent daily administration of McAb in similar doses for five days protected 80% of guinea pigs. Survival rates of three control groups which received physiological saline, ascites of BALB/c mouse myeloma cell lines SP2/0, and monoclonal antibodies against Pseudomonas aeruginosa in place of monoclonal antibodies against outer envelopes of strain 017 leptospires were 10%, 20% and 10% respectively. When killed 20 days after challenge, guinea pigs of experiment group were normal at autopsy. Old pulmonary haemorrhage were present in the animals of three control groups. Passive immunoprotection experiments have demonstrated immunoprotection of monoclonal antibodies against outer envelopes of strain 017 leptospires. It will be valuable for separating protective antigen fraction of outer envelopes and studying new vaccine of leptospira.
Three McAb were produced against an outer envelope preparation from Leptospira, interrogans, serovar Lai by fusion of SP2/0 myeloma cells with immune BALB/c mice spleen cells. The fusion rate was 96% and the antibody positive rate was 50%. One of the hybridomas, E4B11C9, reacted with 13 of the 13 serovars of the Icterohaemorrhagiae serogroup in microscopic agglutination test (MAT) but did not react with the 18 representative serovars of L. interrogans and L. biflexa serovar patoc and Leptonema illini. For all non-reactive serovars the MAT titres were greater than 1:25. The McAb, E4B7G5, reacted similarly with all serovars except smithi and tonkini. E4B7D4 reacted also similarly with all serovars except serovars birkini, ndambari, bogvere, smithi and tonkini. Therefore, 3 McAb showed serogroup specificity and partial serogroup specificity by agglutination. The agglutination titres were high and hybridomas were stable, so it might be useful in providing a simple, rapid method for the classification and identification of clinical isolates such as pathogenic L. interrogans in place of the complicated and time-consuming conventional methods.
PURPOSE: The degree of local tissue toxicity from hepatic arterial chemoembolization relative to the dose of anticancer drugs was evaluated in 13 dogs. MATERIALS AND METHODS: Animals were divided into four groups. Group 1 was the control group in which embolization was performed with gelatin sponge particles only (n = 4); group 2 animals underwent embolization with 0.4 mg/kg of Adriamycin (ADR) and 0.2 mg/kg of mitomycin C (MMC) (n = 4); group 3, with 0.8 mg/kg of ADR and 0.4 mg/kg of MMC (n = 2); and group 4, with 1.6 mg/kg of ADR and 0.8 mg/kg of MMC (n = 3). RESULTS: Animals were killed 1 week after embolization, and histopathologic evaluation was performed. The average percentage liver necrosis in the embolized lobe was 0% in group 1, 1% in group 2, 85% in group 3, and 92% in group 4. CONCLUSION: Hepatic arterial chemoembolization with high doses of anticancer drugs causes severe liver damage, but 0.4 mg/kg of ADR and 0.2 mg/kg of MMC is relatively safe, causing only minimal changes in this canine model.