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Biomedical subjects

Z C Li

Publications and source records attributed to Z C Li.

34 records · Page 2Linked to original sources
PubMed1989

Soluble and Bound Apoplastic Activity for Peroxidase, beta-d-Glucosidase, Malate Dehydrogenase, and Nonspecific Arylesterase, in Barley (Hordeum vulgare L.) and Oat (Avena sativa L.) Primary Leaves.

An intercellular washing solution containing about 1% of the soluble protein, 0.3% or less of the glucose-6-phosphate dehydrogenase activity, but up to 20% of the peroxidase and beta-d-glucosidase activity of barley (Hordeum vulgare L.) or oat (Avena sativa L.) primary leaves was obtained by vacuum infiltrating peeled leaves with pH 6.9 buffered 200 millimolar NaCl. After this wash, segments were homogenized in buffer, centrifuged, and the supernatant was assayed for soluble cytoplasmic enzymes. The pellet was washed and resuspended in 1 molar NaCl to solubilize enzymes strongly ionically bound to the cell wall. The final pellet was assayed for enzyme activity covalently bound in the cell wall. Apoplastic (intercellular washing solution, ionically bound, and covalently bound) fractions contained up to 76% of the beta-d-glucosidase activity, 36% of the peroxidase activity, 11% of the nonspecific arylesterase activity, 4% of the malate dehydrogenase activity, but less than 2% of the glucose-6-phosphate dehydrogenase activity of peeled leaf segments. The partitioning and salt-solubility of the enzymes between the apoplast and symplast differed considerably between these two species. Intercellular washing fluid prepared by centrifuging unpeeled leaves had higher activity for glucose-6-phosphate dehydrogenase, less soluble protein, and less peroxidase activity per leaf than intercellular washing solution obtained by our peeling-infiltration-washing technique. The results are discussed in relation to the roles of these enzymes in phenolic metabolism in the cell wall.

Journal Article↗
PubMed1989

[A study on the retreatment of pulmonary tuberculosis by the addition of 654-2].

654-2 plus chemotherapy were used to retreat TB. After a full course of treatment, rates of negative sputum in the observation group and in the control group were 90.6% and 68.8% respectively (The difference in the rates was statistically significant P less than 0.05). The total rate of focus in the observation group was 46.9% and that in the control group was 21.9%. The difference was striking (P less than 0.05). The general efficacy for cavity alteration in the observation group was 42.3% and in control group was 16.0%. Comparing the two groups, there was an obvious difference (P less than 0.05). After ceasing medication, no relapse was observed through a period of one year in the treated group.

Adolescent↗
PubMed1988

Pial arteriolar vessel diameter and CO2 reactivity during prolonged hyperventilation in the rabbit.

Hyperventilation reduces intracranial pressure (ICP) acutely through vasoconstriction, but its long-term effect on vessel diameter is unknown. In seven rabbits with a cranial window implanted 3 weeks earlier, the effect of prolonged hyperventilation on vessel diameter was studied. Anesthesia was maintained for 54 hours with a pentobarbital drip (1 mg/kg/hr). The pH, CO2, and HCO3- levels were measured in arterial blood and cisterna magna cerebrospinal fluid (CSF). The diameter of 31 pial arterioles was measured with an image splitter. After baseline measurements, pCO2 was reduced from 38 to 25 mm Hg and allowed to return to 38 mm Hg for 10 minutes every 4 hours. There was an initial vasoconstriction of 13%, which progressively diminished by 3% every 4 hours. Thus, by the 20th hour, vessel diameters at a pCO2 of 25 mm Hg had returned to slightly above baseline values obtained at a pCO2 of 38 mm Hg. The temporary return of pCO2 to 38 mm Hg every 4 hours caused vasodilation: 12% at 4 hours, gradually increasing to 16% at 52 hours. Thus, at 52 hours, the vessel diameters were 105% of baseline at a pCO2 of 25 mm Hg and increased to 122% at a pCO2 of 38 mm Hg. Arterial pH had returned to baseline at 20 hours, and CSF pH had returned at 24 hours. Bicarbonate in blood and CSF remained decreased throughout the experiments. In three control experiments during which normocapnia was maintained, vessel diameter and pH and bicarbonate levels remained unaltered over the same period. The CO2 reactivity, tested by brief periods of hyperventilation every 4 hours, also did not change. These results indicate that hyperventilation is effective in reducing cerebral blood volume for less than 24 hours and that it should be used only during actual ICP elevations. If used preventively, its effect may have worn off by the time ICP starts to rise for other reasons, and further decreases in pCO2 cannot be obtained. Moreover, the reduction in buffer capacity with lower bicarbonate renders the vessels more sensitive to changes in PaCO2. This could lead to more pronounced elevations in ICP during transient rises in PaCO2, such as during endotracheal suctioning in head-injured patients.

Animals↗
PubMed1985

Successful separation of xiphoomphalopagus twins.

A pair of female xiphoomphalopagus twins were delivered by Caesarean section at 35th week of gestation on March 2, 1982, their combined weight being 4,800 g. Examinations revealed that they were conjoined from the xiphoid process down to the umbilicus. Infant A also had congenital heart defect (VSD). X-ray and echography showed that they had a fused liver and two independent biliary systems and alimentary tracts. After 6 weeks, the twins gained weight up to 7,000 g. The separation operation was performed at 1 1/2 months of age. During operation it was demonstrated that the xiphoid process and costal cartilages were fused together and the peritoneal cavities were of free communication above the umbilicus, and the livers merged into a single common liver. The large single liver was divided by electrocautery, resulting in a section surface of 8 X 7.5 cm. After separation, the closure of the abdominal wall in both infants presented some difficulties which were resolved by making relaxation incisions on either flanks. In the post operative period, the ventral wounds of both infants were disrupted for several centimetres and infant B had wound infection. The granulating area of skin defect on either relaxation incision of the flanks and ventral denuded wound were covered with full-thickness dead-foetus homografts. The wounds were well healed. Eventually both infants were discharged in good condition at 2 1/2 months after operation. Now they live well at 2 1/2 years of age.

Cesarean Section↗
PubMedDate not supplied

Cyclic mechanical fatigue of a feldspathic dental porcelain.

A blunt-indentation fracture mechanics technique was used to investigate the response of a feldspathic dental porcelain to cyclic mechanical fatigue. The indentation stress-strain curve was determined first, which showed the critical pressure necessary for crack initiation. This research also demonstrated that pressures too small to cause immediate catastrophic failure can still cause irreversible damage. A second series of fatigue experiments, using pressure parameters chosen from the first project investigated strength loss. These experiments showed that the porcelain was susceptible to cyclic mechanical fatigue, and that cyclic mechanical fatigue is different from quasistatic fatigue. Strength loss curves indicated that cyclic mechanical fatigue damage is cumulative and permitted quantification of the severity of accumulated damage.

Aluminum Silicates↗