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Biomedical subjects

J Gao

Publications and source records attributed to J Gao.

At least 451 records · Page 25Linked to original sources
PubMed1993

[Relationship between air pollution and mortality in Dongcheng and Xicheng Districts, Beijing].

Relationship between air pollution and mortality in 1989 was studied in two residential areas in Beijing (Dongcheng District and Xicheng District). The daily number of death was regressed on the logarithmic air levels of sulphur dioxide (SO2) and/or total suspended particulate (TSP) on the same day with Poisson regression method. A highly significant association was found between logarithmic levels of air SO2 and daily number of death adjusted for the influence of temperature and humidity. The stronger effects of them were seen on the death caused by chronic bronchitis, chronic obstructive pulmonary disease and cor pulmonale.

Aged↗
PubMed1993

[Morphometric analysis on the in vitro invasiveness of mouse lung adenocarcinoma variants with different metastatic potential].

The in vitro invasiveness of LA1, LAD, LA5 variants of mouse lung adenocarcinoma (LA795) with different metastatic potentials were examined. Precultured heart fragment (PHF) was used as the target organ, and spheroid aggregates of LA1, LAD, LA5 cells were prepared by cultivation of cell suspension on a gyratory shaker. The invasion-complex was formed by confronting of the PHF and cell aggregate. The invasion-complex was then examined at different time intervals histologically and morphometrically. The micro-computer-aided image analysis system was employed to measure the total area (TA) of the invasion complex and the tumor tissue area (subarea, SA). The ratio of SA/TA was used in estimating the invasion ability. It was shown that the invasion of LA1, LAD and LA5 was progressive in nature and the invasive capability of these three variants were correlative with their metastatic potentials.

Adenocarcinoma↗
PubMed1993

[A retrospective cohort study on long-term health effects of shift work].

A retrospective cohort study was conducted to examine the long-term effects of shift work including night work upon sick leave utilization. The cohort consisted of all blue-collar workers aged 16 to 28 years, who entered a steel production plant between 1967 and 1970, who were then divided into a shift worker group (790 persons) and a day worker group (309 persons) according to their initial baseline work pattern. A 20 year follow-up study of the health administration files of the two groups was performed in November 1991. The main results were as follows: 1. Reasons for and time trends for retirements in the shift worker group were very similar to those in the day worker group. 2. With respect to illnesses needing hospitalization or medically certified absence lasting more than one month, the cumulative incidence rates during a 5-year period and a 10-year period in the shift worker group were 17% and 28% respectively, and 16% and 28% in the day worker group. No significant effect of shift work upon occurrence of illnesses could be found after controlling for factors at entrance and history of engagement in hazardous work although there were differences between the two groups. 3. No significant differences in incidence rates of any diagnostic categories were detected between the groups. 4. Among the workers still employed in 1990, we found no differences in prevalence rates of any diagnostic categories between the groups. These results lead to the conclusion that shift work appears to have no severe adverse effects upon morbidity when there is a high level of health and labor administration.

Absenteeism↗
PubMed1992

A priori evaluation of aqueous polarization effects through Monte Carlo QM-MM simulations.

A Monte Carlo quantum mechanical-molecular mechanical (QM-MM) simulation method was used to determine the contributions of the solvent polarization effect to the total interaction energies between solute and solvent for amino acid side chains and nucleotide bases in aqueous solution. In the present AM1-TIP3P approach, the solute molecule is characterized by valence electrons and nucleus cores with Hartree-Fock theory incorporating explicit solvent effects into the total Hamiltonian, while the solvent is approximated by the three-point charge TIP3P model. The polarization energy contributes 10 to 20 percent of the total electrostatic energy in these systems. The performance of the hybrid AM1-TIP3P model was further validated by consideration of bimolecular complexes with water and by computation of the free energies of solvation of organic molecules using statistical perturbation theory. Excellent agreement with ab initio 6-31G(d) results and experimental solvation free energies was obtained.

Acetates↗
PubMed1992

Identification of breakpoints in t(8;21) acute myelogenous leukemia and isolation of a fusion transcript, AML1/ETO, with similarity to Drosophila segmentation gene, runt.

We have developed a restriction map of the chromosome 21 breakpoint region involved in t(8;21)(q22;q22.3) acute myelogenous leukemia (AML) and have isolated a genomic junction clone containing chromosome 8 and 21 material. Using probes from these regions, rearrangements have been identified in each of nine cases of t(8;21) AML examined. In addition, we have isolated cDNA clones from a t(8;21) AML cDNA library that contain fused sequences from chromosome 8 and 21. The chromosome 8 component, referred to as ETO (for eight twenty-one), is encoded over a large genomic region, as suggested by the analysis of corresponding yeast artificial chromosomes (YACs). The DNA sequence of the chromosome 21 portion of the fusion transcript is derived from the normal AML1 gene. A striking similarity (67% identity over 387 bp, with a corresponding 69% amino acid identity) was detected between AML1 and the Drosophila segmentation gene, runt. The critical consequence of the translocation is the juxtaposition of 5' sequences of AML1 to 3' sequences of ETO, oriented telomere to centromere on the der(8) chromosome.

Amino Acid Sequence↗
PubMed1992

Three years' experience with levonorgestrel-releasing intrauterine device and Norplant-2 implants: a randomized comparative study.

A randomized comparative study of levonorgestrel-releasing intrauterine device (LNG-IUD) and Norplant-2 implants was carried out in 200 women for 36 months. Three thousand one hundred woman-months of use were observed with each device. Only one pregnancy occurred in users of LNG-IUD at the 12th month of use. The change in bleeding pattern was the most frequent reason for discontinuation. The discontinuation rate for irregular bleeding with Norplant-2 was 17.3 and 26.8 at 24 and 36 months, respectively, as compared to 3.3 with LNG-IUD at both 24 and 36 months. The differences were statistically significant. Removal for amenorrhea and pain only occurred in acceptors of LNG-IUD. About 20-40% of women using Norplant-2 had prolonged bleeding through 36 months. The percentage of amenorrhea in LNG-IUD was the highest (29.3%) at the end of two years of use. More than 97% of subjects reported satisfaction with the methods used by themselves.

Adult↗
PubMed1992

Clinical trial on termination of early pregnancy with RU486 in combination with prostaglandin.

Termination of early pregnancy was performed in 1572 healthy women with RU486 (mifepristone, 600mg orally once), followed 36-60 hours later by administration of methyl ester of dl-15-methyl-PGF2 alpha (PG05, 1mg vaginal suppository). Complete abortion was accomplished in 91.2% (1433/1571), incomplete abortion in 4.8% (76/1571), and continued pregnancy in 3.9% (62/1571). The time elapsed between RU486 intake and complete expulsion was 2.4 +/- 1.3 days. Expulsion took place on the third day in 935 women (72%), and on the 4th day in 273 women (21.0%). Uterine bleeding occurred on the second or third day after RU486 intake in 1256 women (88.8%), and lasted 11.7 +/- 6.4 (SD) days, range 2-55 days. One subject had blood transfusion due to excessive bleeding. The main side effects were nausea/vomiting (22.3%), abdominal pain (10.2%), headache/dizziness (4.1%) and diarrhea (2.8%). Fatal side effects have not been reported in this study. About 73% of subjects with complete abortion assessed the treatment as good to excellent. Even in the failed cases, 25-42% of subjects considered the treatment as good. Further studies are needed to determine the optimal dose of the RU486 regimen. It should be emphasized that the treatment must be used under close medical supervision in order to monitor the uterine bleeding.

Abortion, Incomplete↗
PubMed1992

Inhibition of the biological activity of human interferon-gamma by antipeptide antibodies.

To study the domain(s) responsible for the different biological activities of human interferon-gamma (HuIFN-gamma), rabbits were immunized with peptides corresponding to the five most hydrophilic amino acid sequences of the lymphokine. The resulting antisera were able to recognize both the immunizing peptide and the native protein. Antibodies to the carboxy-terminal region (amino acids 125-137) of HuIFN-gamma were able to interfere with the immunomodulating, antiviral, and antiproliferative activities of the lymphokine. Inhibition of the antiproliferative and antiviral activity was also observed using antibodies raised against the amino-terminal region (amino acids 4-16) and amino acids 80-95, respectively, but to a lesser extent than that observed with antibodies to the carboxyl terminus. The capability of these antibody preparations to partially interfere with only one of the lymphokine's biological activities might be explained by a mechanism of steric hindrance. The use of polyclonal antibodies allowed us to limit the presence of epitopes responsible for recombinant (r)HuIFN-gamma biological activities to the carboxy-terminal region.

Antibodies↗
PubMed1992

Isoprenaline, Ca2+ and the Na(+)-K+ pump in guinea-pig ventricular myocytes.

1. The whole-cell patch clamp technique was employed to study the effects of the beta-agonist isoprenaline (ISO) on the Na(+)=K+ pump current, Ip, in acutely isolated ventricular myocytes from guinea-pig hearts. Propranolol, a beta-adrenergic antagonist, was used to demonstrate that all of the effects of ISO, stimulatory or inhibitory, are mediated by beta-receptors. 2. Below about 150 nM [Ca2+]i, we find that ISO reduces Ip, while above this [Ca2+]i ISO increases Ip. The stimulatory and inhibitory effects of ISO on Ip are independent of either intracellular sodium ([Na+]i) or extracellular potassium ([K+]o). These results suggest that the end-effect of ISO is directly on the maximum pump turnover rate (Vmax) rather than indirectly through changes in [Na+]i or [K+]o or modulatory effects on Na+ or K+ affinity. 3. The maximum effect of ISO increases Ip by 25% when [Ca2+] is buffered at 1.4 microM. A half-maximal effect is reached at roughly 10 nM-ISO and a near-maximal effect by 0.5 microM. 4. The permeabilized patch technique, using amphotericin B (Horn & Marty, 1988; Rae, Cooper, Gates & Watsky, 1991), was employed to minimize changes in the normal second messenger systems and calcium buffers. In these experiments, we used a high intracellular sodium solution (pipette sodium was 50 mM), thus sodium-calcium exchange was depressed and we expected [Ca2+]i to be above 150 nM. ISO increases Ip in these conditions as in the dialysed cells. 5. Our results suggest that beta-stimulation can increase Ip, but only if [Ca2+]i is above about 150 nM. In the beating heart [Ca2+]i rises well above this value during systole and the average [Ca2+]i, which depends on heart rate, is expected to normally be above this level. During beta-stimulation, the increase in Ip along with a concomitant increase in IK (Giles, Nakajima, Ono & Shibata, 1989; Duchatelle-Gourdon, Hartzell & Lagrutta, 1989) helps prevent action potential lengthening and allows an increase in heart rate even in the presence of increased calcium current. Further, beta-stimulation will compensate for the effects on Ip of either hypokalaemia or digitalis toxicity, and so reduce the expected rise in both [Na+]i and [Ca2+]i.

Animals↗
PubMed1992

The production of hybridoma cell line secreting monoclonal antibodies against Xanthomonas campestris pv. oryzae and its application in the classification of strains.

By the fusion of mouse myeloma cells (SP2/0-Ag14) and spleen cells derived from BALB/c mice immunized with the preparation of Xanthomonas campestris pv. oryzae Ks-6-6, Os-213, Yz-32 and Yz-24, we obtained 12 hybridoma cell lines secreting monoclonal antibodies. None of the McAbs cross-reacted with the other varieties of plant pathogenetic and non-pathogenetic bacteria. The McAbs could distinguish three variant serotypes of strains. Antibody titers of ascites were about 1:10(3)-1:10(6) when measured by ELISA method. The McAbs could differentiate 6 epitopes. Based on the epitopes, the 63 strains of X. campestris pv. oryzae we collected were grouped into nine groups.

Animals↗
PubMed1992

[Location of ctDNA fragment related to CMS in Brassica napus L. var. xiangai].

The ctDNA of sterile line and its maintainer from Brassica napus L. var. xiangai were digested by restriction endonucleases EcoRI, BamHI, PstI and SmaI. Only one special fragment E3.2kb was observed in EcoRI restriction pattern of maintainer. After being eluted, this fragment was incubated with plasmid pUC9 and then transformed E. coli JM83. Through colour screening, clony hybridization and electrophoretic analyses, the special clone carrying E3.2 was obtained. The rRNA gene probe was used to hybridize with the EcoRI restriction pattern. The result showed that E3.2kb fragment is homologous to rRNA gene. And then, we use E3.2 fragment as probe to hybridize with rRNA gene digested by BamHI, EcoRI, SalII, BglII, HindIII and PstI. According to rRNA gene map, E3.2 fragment was located at the leader sequence of 16S rRNA gene, from +2.0kb to +5.4kb. Because this 3.4kb region was in the inverted repeat region of ctDNA and it is homologous to E3.2kb that related to CMS. So probably CMS is related to this 3.4kb region in the inverted repeat region of ctDNA.

Brassica↗