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Biomedical subjects

J Cao

Publications and source records attributed to J Cao.

At least 343 records · Page 19Linked to original sources
PubMed1991

[Isolation and characteristics of Borrelia burgdorferi from Ixodes persulcatus].

We reported the detailed characteristics of Lyme disease spirochetes (Borrelia burgdorferi), strain H7, isolated from Ixodes persulcatus in Heilongjiang. Cells of strain H7 were 9.8--26.5 microns long and 0.13--0.35 microns wide. There were 1--11 waves with a wavelength of 1.2--3.0 microns and an amplitude of 0.59--1.13 microns. Direction of spires was left. Seven flagella were inserted subterminally at each end of the cell and ends were pointed. 31 degrees C was the optimum cultural temperature in vitro. The major constitutional and antigenic proteins were 21k, 32k and 34k proteins. H7 could react on the patient sera of Xinjiang and Heilongjiang with IFA and western blot. These findings demonstrated that strain H7 belonged to species Borrelia burgdorferi, but was a new "subtype" which differed from the strains isolated from other areas and vectors.

Animals↗
PubMed1990

Low density lipoprotein activates monocytes to express tumor necrosis factor.

We analyzed the effect of acetylated low density lipoprotein (aLDL) incubation on tumor necrosis factor (TNF) mRNA and protein expression in isolated resting human monocytes in serum free DMEM. TNF mRNA expression was about one third that of PMA and was dose dependent. The maximum stimulatory effect on TNF mRNA was at 250 micrograms/ml, while 500 micrograms/ml induced downregulation. The maximum stimulatory effect occurred at 6 hours, and by 24 hours TNF mRNA expression returned to the resting state. Acetyl LDL also induced the expression of immunoreactive TNF, reaching a sevenfold maximum above control at 12 hours following a 6 hour exposure period. The results suggest that aLDL is a potent stimulator of TNF expression in resting monocytes. This mechanism may be operational in atheroma evolution.

Blotting, Northern↗
PubMed1990

Chlorophyll a fluorescence transient as an indicator of active and inactive Photosystem II in thylakoid membranes.

Upon illumination, a dark-adapted photosynthetic sample shows time-dependent changes in chlorophyll (Chl) a fluorescence yield, known as the Kautsky phenomenon or the OIDPS transient. Based on the differential effects of electron acceptors such as 2,5-dimethyl-p-benzoquinone (DMQ) and 2,6-dichloro-p-benzoquinone (DCBQ) on Chl a fluorescence transients of spinach thylakoids, we suggest that the OID phase reflects the reduction of the electron acceptor QA to QA- in the inactive PS II (see Graan, T. and Ort, D. (1986) Diochim. Biophys. Acta 852, 320-330). In spinach thylakoids, heat-induced increase of the Chl a fluorescence yield is also differentially sensitive to the addition of DMQ and DCBQ suggesting that this increase is mainly on the 'I' level, and thus heating is suggested to convert active PS II to inactive PS II centers. The kinetics of decay of QA-, calculated from variable Chl a fluorescence, was analyzed into three exponential components (365-395 microseconds; 6-7 ms; and 1.4-1.7 s). In heated samples, the decay rate of variable Chl a fluorescence is slower than the normal back-reaction rate; there is a preponderance of the slow component that may be due, partly, to the active centers undergoing slow back reaction between QA- and the S2 state of the oxygen-evolving complex.

Benzoquinones↗
PubMed1990

Detection and localization of tumor necrosis factor in human atheroma.

Tumor necrosis factor (TNF) is a secretory product of normal macrophages that can cause cell necrosis, new blood vessel formation and thrombosis. These are also 3 characteristic features of the progression of stable atheroma to endothelial disruption. Accordingly, an immunohistochemical method was developed to detect TNF in human tissue. Using this method TNF positivity was demonstrated in 57 of 65 (88%) of tissue sections classified as atherosclerotic and in 5 of 11 (45%) sections classified as minimally atherosclerotic. TNF was absent in 6 sections classified as normal. TNF positivity was found not only in the cytoplasm of macrophages, but also in the cytoplasm and attached to the cell membrane of smooth muscle cells and endothelial cells of the human atheroma. Because TNF is known to cause new vessel formation, hemorrhagic necrosis and increased thrombogenicity, it may play a role in the evolution of uncomplicated to complex atheroma.

Antibodies, Monoclonal↗
PubMed1990

Isolation of an efficient actin promoter for use in rice transformation.

We have characterized the 5' region of the rice actin 1 gene (Act1) and show that it is an efficient promoter for regulating the constitutive expression of a foreign gene in transgenic rice. By constructing plasmids with 5' regions from the rice Act1 gene fused to the coding sequence of a gene encoding bacterial beta-glucuronidase, we demonstrate that a region 1.3 kilobases upstream of the Act1 translation initiation codon contains all of the 5'-regulatory elements necessary for high-level beta-glucuronidase (GUS) expression in transient assays of transformed rice protoplasts. The rice Act1 primary transcript has a noncoding exon separated by a 5' intron from the first coding exon. Fusions that lack this Act1 intron showed no detectable GUS activity in transient assays of transformed rice protoplasts. Deletion analysis of the Act1 5' intron suggests that the intron-mediated stimulation of GUS expression is associated, in part, with an in vivo requirement for efficient intron splicing.

Actins↗
PubMed1990

Tumor necrosis factor gene expression in human vascular intimal smooth muscle cells detected by in situ hybridization.

We used immunohistochemistry to detect tumor necrosis factor (TNF) and in situ hybridization to detect TNF messenger RNA (mRNA) in the intimal mesenchymal-appearing cells and in the medial smooth muscle cells of human atherosclerotic arteries. Medial smooth muscle cells showed localization of immunoreactive TNF on the cell surface and did not express TNF mRNA. Conversely, in intimal mesenchymal-appearing cells, TNF was localized in the cytoplasm and TNF mRNA was expressed by in situ hybridization. Thus 89% of intimal cells were immunohistochemically positive for TNF, 96% of them were positive by in situ hybridization, and 76% were positive for the smooth muscle cell marker, HHF35. Our results suggest that intimal mesenchymal-appearing cells are mostly, but not exclusively, derived from smooth muscle cells. These cells express TNF, whereas the medial smooth muscle cells in the atherosclerotic human arteries do not. The expression of TNF by these mesenchymal-appearing cells may have implications regarding the evolution of the atherosclerotic plaque.

Arteries↗
PubMed1990

[Inhibition of growth and metastases of lung carcinoma in C57BL/6 mice by Corynebacterium parvum and its antitumor mechanism].

Cocrynebacterium parvum (CP) was injected around the tumor and tumor cells were inoculated subcutaneously with activated peritoneal macrophages. The effects on the growth and metastases of Lewis lung carcinoma in C57BL/6 mice were observed. Experimental results indicated that CP had significant inhibitory effect on the tumor growth and lung metastases. The cytotoxic effects of activated peritoneal macrophages in mice on target tumor cells (L5178Y) in vitro were studied with the technique of 3H-TdR assay. The proliferation of tumor cells was markedly inhibited by the activated peritoneal macrophages of CP. Experiments showed that the antitumor mechanism of CP was the mediation via activated cytotoxic macrophages. These results indicated that CP is an effective immunostimulant. These findings will provide a scientific basis for the clinical treatment of the primary and metastatic lung carcinoma.

Adjuvants, Immunologic↗
PubMed1990

Inhibitory effects of ginsenoside Rg1 and Rb1 on rat brain microsomal Na+,K(+)-ATPase activity.

Rat brain microsomal Na+, K(+)-ATPase activity was inhibited significantly and rapidly by ginsenoside Rb1. The IC50 of Rb1 for Na+,K(+)-ATPase was 6.3 +/- 1.0 mumol/L. The inhibition was enhanced with increasing the concentration of Rb1 or decreasing that of Na+ and K+. Kinetic analysis revealed that ginsenoside was an uncompetitive inhibitor with respect to ATP. The inhibitory effect of Rg1 on rat brain microsomal Na+,K(+)-ATPase was much weaker than that of Rb1.

Animals↗
PubMed1989

The family center--a new form of organization for rural family planning.

The history and functions of rural family planning centers in China are reviewed, with a focus on a center in Liaoning Province. "To date, more than 8,500 such centers have been established in 92.2 percent of the rural resident's groups. What the centers do is to give rural residents education and services in family planning, and help them educate themselves.... According to statistics, 99.3 per cent of the babies born in Liaoning Province in 1986 were planned. More than half of the counties and districts and over 90 per cent of the villages reported no unplanned births. The Province now leads the nation in fulfillment of family-planning goals."

Asia↗
PubMed1989

[A study on indolepyruvic acid methyltransferase in chuangxinmycin-producing strain].

The indolepyruvic acid methyltransferase, perhaps which is active in the biosynthetic pathway of the antibiotic chuangxinmycin, has been detected and partially purified from cell-free extracts of Actinoplanes jinanensis n. sp., This enzyme catalyzes the transfer of a methyl group from S-adenosylmethionine to indolepyruvic acid. The methyltransferase has been purified 60-fold by ammonium sulfate fractionation and DEAE-cellulose column chromatography. The enzyme optimal substrate is indolepyruvic acid. The enzyme has a pH optimum of 7.5. The double reciprocal plots gave Km values of 4.0 X 10(-5) mol/L for S-adenosylmethionine and 1.8 X 10(-7) mol/L for indolepyruvic acid. A molecular weight of 55000 +/- 5000 has been determined by Sephadex G-150 gel filtration.

Actinomycetales↗
PubMed1987

Experiences with gossypol as a male pill.

In 1981 to 1983 we performed a clinical study with gossypol involving 152 participants, and in 1983 to 1985 we conducted another study of 120 participants. The first study was aimed at confirming gossypol's antifertility efficacy and determining the existence of side effects. The objective of the latter study was to find out whether the addition of a potassium salt supplement or a potassium-sparing agent could alleviate the side effect of hypokalemia. In both studies, the participants took a gossypol pill, 20 mg/day for 60 to 75 days for loading, and 50 mg/wk for maintenance. All participants were followed up for a year. The antifertility efficacy was found to be more than 90%, and the chief side effect was lowered serum potassium. In our 1983 to 1985 study, we concluded that since neither potassium supplementation nor triamterene solved the problem, it is very likely that gossypol is a nephrotoxic agent. With 1 year of gossypol treatment, serum testosterone and serum luteinizing hormone showed no change, whereas serum follicle-stimulating hormone showed some elevation after 6 months. The Shanghai researchers found that in their gossypol users, plasma and urinary beta 2-microglobulin levels were elevated to a certain extent. However, 25 subjects in our 1983 to 1985 study showed no appreciable change. Our volunteers had stopped taking gossypol for more than 1 year. In 1986 we started a third study, which was aimed at finding the lowest antifertility dose to minimize possible renal toxicity.

Clinical Trials as Topic↗
PubMed1987

Clinical trial of gossypol as a male contraceptive drug. Part I. Efficacy study.

The main objective of the research is to study the effectiveness and safety of gossypol as a male contraceptive drug. Using a double-blind, randomized, controlled study design, gossypol was found to be an effective male antifertility drug, with no adverse effects on libido nor appetite. In terms of serum potassium levels, there were no statistical differences between gossypol and placebo groups at the end of the loading phase. However, through the ensuing 12 months of maintenance phase, a statistically significant trend toward reduced serum potassium level was evident.

Appetite↗