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Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 1,099 records · Page 61Linked to original sources
PubMed1988

Absence of Variable Fluorescence from Guard Cell Chloroplasts of Stenotaphrum secundatum.

The lack of detectable variable fluorescence from guard cell chloroplasts in both the albino and green portions of variegated leaves of St. Augustine grass (Stenotaphrum secundatum var variegatum A.S. Hitchc.) is reported. Fluorescence was measured either with a highly sensitive, modified fluorescence microscope which was capable of recording fluorescence induction curves from single chloroplasts, or with a spectrofluorometer. Both fast and slow fluorescence transients from S. secundatum guard cells showed a rapid rise and then remained at a steady level. Neither variable fluorescence increase (induction) nor decrease (quenching), properties normally associated with photosystem II, was observed from these chloroplasts. These fluorescence kinetics did not change either with alterations of the specimen preparation procedure or with alterations of the excitation light intensities and wavelengths. These results indicate that guard cell chloroplasts in this variety of S. secundatum do not conduct normal photosystem II electron transport. Light regulation of stomatal conductance in intact leaves of this plant did occur, however, and was similar to light regulation observed in other species. The conductance of the green portion of the leaves was much greater in the light than in the dark, and was much greater than the conductance of the albino portion of the leaves. Stomata in the green portion of the leaves also showed greater opening in blue light than in red light. These results provide evidence that stomatal regulation in this variety of S. secundatum does not rely on photosystem II electron transport in guard cell chloroplasts.

Journal Article↗
PubMed1988

[Immunohistochemical study of alpha-1-antichymotrypsin and GFAP in glioma].

GFAP is a specific antigen of glial element, but Alpha-1-antichymotrypsin has not been reported in the literature Alpha-1-antichymotrypsin was guided by GFAP using PAP method to the astrocytes of 137 gliomas. 120 (87%) gliomas were positive for Alpha-1-antichymotrypsin. Of these 120 gliomas, 86 (72%) gave diffuse distribution, 17 (14%) gave focal distribution, and 17 (14%) gave scattered distributions. Alpha-1-antichymotrypsin in glioma tissue may be an important tumor marker for diagnosis.

Astrocytoma↗
PubMed1987

Quantitation of intracellular free calcium in single adult cardiomyocytes by fura-2 fluorescence microscopy: calibration of fura-2 ratios.

Isolated rat myocytes incubated with the acetoxy methyl ester of fura 2 contained partially hydrolyzed esters, necessitating in vivo calibration of the signals obtained by fluorescence microscopy for calculation of pCa. Ionophores did not produce reliable R'max and R'min values in respiring myocytes, and elevated free calcium caused individual cells to hypercontract and burst. These difficulties were overcome by superfusion with a glucose-free buffer containing an inhibitor and an uncoupler of oxidative phosphorylation. R'max and R'min values obtained by ionophore treatment of deenergized myocytes were normalized to an in vitro calibration curve. Resting pCa derived from the individual curves averaged 6.9 for calcium-tolerant rod-shaped myocytes.

Adenosine Triphosphate↗
PubMed1987

Occupational exposure to benzene in China.

Of a total of 528,729 workers exposed to benzene or benzene mixtures in China, 508,818 (96.23%) were examined. Altogether 2,676 cases of benzene poisoning were found, a prevalence of 0.15%. A higher prevalence of benzene poisoning was found in the cities of Hangjou, Hefei, Nanjing, Shenyang, and Xian. The geometric mean concentration of benzene in 50,255 workplaces was 18.1 mg/m3 but 64.6% of the workplaces had less than 40 mg/m3. There was a positive correlation between the prevalence of benzene poisoning and the concentration in shoemaking factories. The prevalence of benzene induced aplastic anaemia in shoemakers was about 5.8 times that occurring in the general population. The results of this investigation show the need for a practicable hygiene standard to prevent benzene poisoning.

Adult↗