Search PubMed⌕ Search

Biomedical subjects

W Cao

Publications and source records attributed to W Cao.

At least 163 records · Page 9Linked to original sources

[Clinical application of the visual suppression test].

200 cases of peripheral and central vestibular disorder patients were examined by caloric test and visual suppression test (VS) simultaneously. The results with ENG recording showed: (1) VS score > 50% indicates normal function. (2) VS score 50%-10% is function decreased. (3) VS score < 10% shows function failure. (4) Patients with negative VS score accompanies nystagmus strengthen with eye open when in the light also, the clinical application of the VS test for diagnosis of several kinds of vestibular disorder were discussed.

Acoustic Stimulation↗

[Effects of ligustrazine and nitroglycerine on acute hypoxic pulmonary hypertension in anesthetized dogs].

The effects of ligustrazine and nitroglycerine on acute hypoxic pulmonary hypertension were observed in 10 anesthetized dogs. The results showed that ligustrazine (40 mg/kg) significantly reduced the hypoxic mean pulmonary artery pressure (PAPm) and pulmonary vascular resistance (PVR) the 10th and 15th minute after its injection into the right atrium, respectively. Its action was blocked by the continuous intravenous injection of methylene blue (1 mg/kg/min). It was suggested that the action of ligustrazine could be mediated by endothelium-derived relaxing factor. It was also discovered that nitroglycerine (40 micrograms/kg) could quickly decrease PAPm and PVR, indicating that nitroglycerine can be used to treat acute pulmonary hypertension and the aggravation of chronic cor pulmonale.

Acute Disease↗

[Electronystagmographic changes in patients with posterior cranial fossa tumors].

Findings of electronystagmography in 30 patients with posterior cranial fossa tumor were analysed. Of the 23 cases of CPA tumor, size varied between 0.7-5.0 cm, the ENG showed: (1) The nystagmus occurred in 83% of patients. (2) In ODT, overshoots was showed in 22% of patients. (3) ETT showed type III or IV curves in 55.6% of patients. (4) OKP test decreased in 59% of patients. (5) Caloric test showed canal paresis in 85% of the patients. (6) Abnormal visual suppression test occurred in 60% of patients. (7) Abnormal ABR was found in 89% of patients. We also found that tumor larger than 2.5 cm presented a central type nystagmus (Bruns nystagmus) and involvement of the eye movement system. The electronystagmographic changes of the tumors of cerebellum (3 cases) and brain stem (4 cases) was discussed.

Adolescent↗

Crystal structure of cyclophilin A complexed with substrate Ala-Pro suggests a solvent-assisted mechanism of cis-trans isomerization.

Cyclophilin is a binding protein for the immunosuppressive drug cyclosporin A and is also an enzyme with peptidyl-prolyl cis-trans isomerase activity. The crystal structure of cyclophilin A complexed with the substrate Ala-Pro has been determined and refined to an R factor of 0.196 at 1.64-A resolution. The structure shows that only the cis form of Ala-Pro binds cyclophilin A despite the fact that Ala-Pro has an equilibrium majority of the trans form in solution. Simulation of the cis-trans isomerization in an ESV10 graphics system suggests a solvent-assisted mechanism in which first the peptidyl-prolyl bond is desolvated at the ground state by binding to the hydrophobic pocket of the active site, and later the intermediate state is stabilized by a hydrogen bond between the carbonyl oxygen of the amide bond and a bound water molecule.

Amino Acid Isomerases↗

Genetic and biochemical characterization of ISP6, a small mitochondrial outer membrane protein associated with the protein translocation complex.

To search genetically for additional components of the protein translocation apparatus of mitochondria, we have used low fidelity PCR mutagenesis to generate temperature-sensitive mutants in the outer membrane translocation pore component ISP42. A high copy number suppressor of temperature-sensitive isp42 has been isolated and sequenced. This novel gene, denoted ISP6, encodes a 61 amino acid integral membrane protein of the mitochondrial outer membrane, which is oriented with its amino-terminus facing the cytosol. Disruption of the ISP6 gene is without apparent effect in wild type yeast cells, but is lethal in temperature-sensitive isp42 mutants. Immunoprecipitation of the gene product, ISP42p, from mitochondria solubilized under mild conditions reveals a multi-protein complex containing ISP6p and ISP42p.

Amino Acid Sequence↗

Dextromethorphan attenuates the effects of ischemia on rabbit electroretinographic oscillatory potentials.

Dextromethorphan has been shown to protect against ischemic tissue damage. We investigated the effects of dextromethorphan on electroretinographic oscillatory potentials in retinal ischemia. Retinal ischemia was induced in rabbits by increasing intraocular pressure to 120 mm Hg for 30, 60 or 90 minutes. Dextromethorphan was intravenously administered before ischemia and maintained throughout the whole period of experiments. Oscillatory potentials were recorded before and during ischemia as well as 4 hours of recirculation after ischemia. As expected, all oscillatory potentials were decreased after 60 and 90 minutes of ischemia. However, after 30 minutes of ischemia followed by 4 hours of recirculation, amplitudes of P2 were elevated whereas those of P3 and P4 were decreased with normal P1 amplitudes. Dextromethorphan administration diminished the effects of 30 minutes of ischemia on oscillatory potentials and partially attenuated the effects of 60 minutes of ischemia, whereas the effects of 90 minutes of ischemia could not be reversed by dextromethorphan treatment. These results indicate that electroretinographic oscillatory potentials could be useful indicators to evaluate retinal function in the ischemic condition and that dextromethorphan can attenuate the effects of relatively short periods of ischemia on rabbit electroretinographic oscillatory potentials.

Acute Disease↗

A genetic comparison of behavioral actions of ethanol and nicotine in the mirrored chamber.

Human alcoholics are almost invariably heavy users of tobacco, perhaps because both ethanol and nicotine may have anxiolytic activity. However, studies in humans have not uniformly detected anxiolytic effects because significant individual differences in anxiolytic actions of these agents seem to exist. One factor that seems to contribute to these individual differences is tolerance to ethanol. Individuals who are more sensitive to depressant actions of alcohol seem to show anxiolytic actions more readily. Consequently, we examined the relative sensitivities of the ethanol-sensitive (to the anesthetic actions of ethanol) long-sleep (LS) and ethanol-resistant short-sleep (SS) mouse lines to diazepam, ethanol, nicotine, and ethanol-nicotine combinations in the mirrored chamber test. This test measures approach-conflict behavior. Ethanol and nicotine evoked changes in mirrored chamber activities that resembled those elicited by diazepam. These effects were seen at doses that did not markedly affect locomotor activity, thereby suggesting that these changes in behavior represent anxiolytic actions. The LS-SS mice did not differ in sensitivity to diazepam, but the SS were more uniformly responsive to the other drugs. Only the SS showed clear evidence for interactions between ethanol and nicotine. If the changes in mirrored chamber behavior elicited by ethanol, nicotine, and combinations of the two drugs occur because of anxiety reduction, it seems that the SS mouse line is more responsive to anxiolytic actions of these drugs.

Animals↗

Effects of calcitonin gene-related peptide on the rabbit electroretinogram.

In order to better understand the role of Calcitonin gene-related peptide (CGRP) in mammalian retina, the dose related effects of human CGRP (hCGRP) on rabbit electroretinogram (ERG) were examined in the present study. CGRP was administered intraocularly in doses of 0.1, 1.0 and 10.0 micrograms. ERG A- and B-wave as well as oscillatory potentials (P1, P2, P3 and P4) were recorded. The highest dose of CGRP (10.0 micrograms) significantly increased the amplitudes of the A-wave and OP components (P1, P2, P3 and P4) produced by relatively high stimulus intensity. The same dose of the peptide also enhanced B-wave amplitude at all intensities studied. The effects of the intermediate dose of CGRP (1.0 microgram) on the B-wave amplitudes were dependent on stimulus intensities. B-wave amplitudes at high stimulus intensities were not affected by 1.0 microgram of CGRP but were significantly increased with relatively lower stimulus intensities. The amplitudes of P3, one of OP components, were significantly increased. However, amplitudes of A-wave and other OP components (P1, P2 and P4) were not affected by 1.0 microgram CGRP. The lowest dose of the peptide (0.1 microgram) did not affect any amplitudes of ERG components. Implicit times of A-wave, B-wave and OP components were not significantly affected by the different doses of CGRP. Taken together, these results indicate that CGRP may play a functional role in modulating retinal responses to photic stimulation.

Animals↗

Study of various NH4+/NO3- mixtures for enhancing growth of potatoes.

Two experiments were conducted to determine the effects of various NH4(+)-N/NO3(-)-N percentages on growth and mineral concentrations in potato (Solanum tuberosum L.) plants using a non-recirculating nutrient film system in a controlled environment. The first experiment included six NH4(+)-N/NO3(-)-N percentages at 0/100, 20/80, 40/60, 60/40, 80/20, and 100/0 with the same total N concentration of 4 mM. The second experiment included six NH4(+)-N/NO3(-)-N percentages at 0/100, 4/96, 8/92, 12/88, 16/84, and 20/80 again with the same total N of 4 mM. In each experiment, plants were harvested 35 days after transplanting when tubers had been initiated and started to enlarge. Dry weights of shoots, tubers, and whole plant at the harvest were increased significantly with all mixed nitrogen treatments as compared with single NH4+ or NO3- form. The enhanced growth with mixed nitrogen was greatest at 8% to 20% NH4(+)-N. Also, the concentrations and accumulation of total N in the shoots and roots were greater with mixed nitrogen than with separate NH4+ or NO3- nutrition. With NH4+ present in the solutions, the concentrations of P and Cl in the shoots were increased compared to NO3- alone, whereas the tissue concentrations of Ca and Mg were decreased. It was concluded that nitrogen fertilization provided with combined NH4+ and NO3- forms, even at small proportions of NH4+, can enhance nitrogen uptake and productivity in potato plants.

Dose-Response Relationship, Drug↗

[Effects of electroacupuncture at different frequencies on the nociceptive response and central contents of GABA and glutamic acid in arthritic rats].

It has been demonstrated that electroacupuncture (EA) produces analgesia in acute arthritic animal models, while the differential analgesic effects at different EA parameters remains to be discovered. In the present experiment, the effects of EA at 100 Hz and 15 Hz on bilateral Yanglingpuan acupoints of the arthritic rats was studied. The results showed: 1) 15Hz EA was more effective than 10Hz EA for analgesia; 2) spinal glutamic acid content of the 15-Hz EA group was significantly lower than that of the 100-Hz EA group, and 3) no significant difference in GABA contents between the two groups was found. The results suggest that spinal glutamic acid may be involved in the different analgesic effects of EA at different frequencies in arthritic rats.

Acupuncture Analgesia↗

[Quantitative and qualitative observations of spleens removed from patients].

UNLABELLED: The spleens of 100 patients (ITP 60 cases, hypersplenism 20 cases, traumatic rupture of spleen 20 cases) were examined histologically and by electron microscopy. Measurements of the spleens removed from ITP patients were taken and compared to those of the other two groups. Short and long term post operative results were compared. RESULTS: 1. Spleens from the ITP group had characteristics different from those from the hypersplenism (hepatocirrhosis) and control groups; 2. the ITP patients whose spleen is twice the weight of average had better long term response to splenectomy; 3. the mean diameter of splenic follicles greater than 500 microns and the average diameter of germinal centers greater than 200 microns were the criteria for long term response to splenectomy. Therefore, histological examination of excised ITP spleen can predict the possible long term effect of splenectomy.

Adolescent↗

Effects of experimentally induced ischemia on dopamine metabolism in rabbit retina.

PURPOSE: To determine the role of dopamine in experimentally induced retinal ischemia. Experiment 1 was designed to study the effects of ischemic levels on dopamine (DA) metabolism. Experiment 2 evaluated the effects of ischemic duration on DA metabolism. The effects of recirculation time after ischemia on DA metabolism were investigated in experiment 3. METHODS: Ischemia was produced by raising intraocular pressure (IOP) in rabbits. Three levels of ischemia were used--level A, level B, and level C--representing 50%, 75%, and 100%, respectively, of the IOP necessary to produce total ischemia. Retinal levels of DA and its main metabolites, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC), were measured by high-performance liquid chromatography with electrochemical detection. RESULTS: Experiment 1 showed that at ischemic level B, DA contents were significantly reduced, but neither DOPAC nor HVA concentrations were altered. The reductions of retinal DA, DOPAC, and HVA concentrations were seen at level C without altering the ratio index. Level A ischemia did not alter DA metabolism. In experiment 2, significant reductions in DA, DOPAC, and HVA concentrations were found at both 30 and 60 minutes in the ischemic group, whereas the ratio DOPAC/DA and (HVA + DOPAC)/DA were significantly decreased only in the 60-minute ischemic group. Five-minute total ischemia did not alter DA metabolism. In experiment 3, concentrations of DA were still significantly decreased at 30 minutes of recirculation after ischemia, but DOPAC and HVA levels were back to normal. However, the ratios of DOPAC/DA, HVA/DA, and (HVA + DOPAC)/DA were significantly elevated. After 90 and 240 minutes of recirculation, retinal DA contents had returned to normal values, but DOPAC and HVA concentrations as well as all ratio indices of DA metabolism were still enhanced. CONCLUSION: Dopamine metabolism is altered during and after retinal ischemia. Dopamine may play a contributing role in ischemia.

3,4-Dihydroxyphenylacetic Acid↗

Utilization of potatoes for life support in space. V. Evaluation of cultivars in response to continuous light and high temperature.

Twenty-four potato (Solanum tuberosum L.) cultivars from different regions of the world were evaluated in terms of their responses to continuous light (24 h photoperiod) and to high temperature (30 C) in two separate experiments under controlled environments. In each experiment, a first evaluation of the cultivars was made at day 35 after transplanting, at which time 12 cultivars exhibiting best growth and tuber initiation were selected. A final evaluation of the 12 cultivars was made after an additional 21 days of growth, at which time plant height, total dry weight, tuber dry weight, and tuber number were determined. In the continuous light evaluation, the 12 selected cultivars were Alaska 114, Atlantic, Bintje, Denali, Desiree, Haig, New York 81, Ottar, Rutt, Snogg, Snowchip, and Troll. In the high temperature evaluation, the 12 selected cultivars were Alpha, Atlantic, Bake King, Denali, Desiree, Haig, Kennebec, Norland, Russet Burbank, Rutt, Superior, and Troll. Among the cultivars selected under continuous irradiation, Desiree, Ottar, Haig, Rutt, Denali and Alaska showed the best potential for high productivity whereas New York 81 and Bintje showed the least production capability. Among the cultivars selected under high temperature, Rutt, Haig, Troll and Bake King had best performance whereas Atlantic, Alpha, Kennebec and Russet Burbank exhibited the least production potential. Thus, Haig and Rutt were the two cultivars that performed well under continuous irradiation and high temperature conditions, and could have maximum potential for adaptation to varying stress environments. These two cultivars may have the best potential for use in future space farming in which continuous light and/or high temperature conditions may exist. However, cultivar responses under combined conditions of continuous light and high temperature remains for further validation.

Environment, Controlled↗

Growth, carbon dioxide exchange and mineral accumulation in potatoes grown at different magnesium concentrations.

Plants of Norland potatoes (Solanum tuberosum L.) were maintained for 42 days at Mg concentrations of 0.05, 0.125, 0.25, 1, 2, and 4 mM in a nonrecirculating nutrient film system under controlled environment. With the increased Mg supply from 0.05 to 4 mM, Mg concentrations in the leaves of the 42-day old plants increased significantly from 1.1 to 11.2 mg g-1 dry weight. Plant leaf area and plant and tuber dry weights increased with increased Mg concentrations up to 1 mM in solution or 6.7 mg g-1 in leaves, and then decreased with further increases in Mg concentrations. Rates of CO2 assimilation measured on leaflets in situ at ambient and various intercellular CO2 concentrations were consistently lower at 0.05 and 4 mM Mg than at other Mg treatments, which may indicate decreased photosynthetic activity in mesophyll tissues at the lowest and highest Mg concentrations. Dark respiration rates in leaves were highest at 0.05 and 4 mM Mg, lowest at 0.25 and 1 mM Mg, and intermediate at 0.125 and 2 mM Mg. The different Mg treatments also influenced accumulation of other minerals in leaves. Leaf concentrations of Ca and Mn decreased with increased Mg supply except that Ca and Mn were lower at 0.05 mM than at 0.125 mM Mg. Leaf K concentrations were lower at 1, 2 and 4 mM Mg than at other Mg treatments. Foliar concentrations of P, Fe, Zn, and Cu had small but inconsistent variation with different Mg concentrations. Leaf concentrations of N, S, and B were similar at different Mg concentrations. This study demonstrates that various Mg nutrition, along with altered accumulation of other nutrients, could regulate dry matter production in potatoes by affecting not only leaf area but also leaf carbon dioxide assimilation and respiration.

Carbon Dioxide↗

Temperature cycling periods affect growth and tuberization in potatoes under continuous irradiation.

Plants of the potato (Solanum tuberosum L.) cultivars Denali, Norland, Haig and Kennebec were grown for 42 days under three temperature cycling periods (thermoperiods) with continuous irradiation in two repeated experiments to help determine if temperature cycling might be varied to optimize tuber development of potatoes in controlled environments. Thermoperiods of 6/6 hours, 12/12 hours and 24/24 hours were established with the same temperature change of 22/14C and same controlled vapor pressure deficit of 0.60 kPa. The thermoperiod of 24/24 hours significantly promoted tuber initiation but slowed tuber enlargement in all four cultivars, compared to the thermoperiods of 6/6 hours and 12/12 hours. Denali' produced the highest tuber and total dry weights under the 6/6 hours thermoperiod. Kennebec' produced the highest tuber dry weight under the 12/12 hours thermoperiod. Thermoperiods had no significant effect on shoot and root dry weights of any cultivars. The major effect of thermoperiods was on initiation and enlargement of tubers.

Environment, Controlled↗