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Biomedical subjects

L Zhao

Publications and source records attributed to L Zhao.

At least 343 records · Page 19Linked to original sources
PubMed1996

Cardioprotection with ischemic preconditioning and MLA: role of adenosine-regulating enzymes?

Both ischemic preconditioning and pretreatment with the endotoxin derivative monophosphoryl lipid A (MLA) protect the heart against infarction, yet the cellular mechanisms responsible for the cardioprotection achieved with either intervention are unknown. Using pentobarbital-anesthetized dogs, we tested the hypothesis that increased activity of 5'-nucleotidase (5'-NT), the enzyme that catalyzes the formation of adenosine from AMP, may play a role. Twenty-two dogs underwent 1 h of coronary occlusion and 4 h of reperfusion: eight controls received no intervention, seven animals were preconditioned with four 5-min episodes of brief ischemia, and seven received MLA (35 micrograms/kg iv) 24 h previously. Collateral blood flow was measured by injection of radiolabeled microspheres, infarct size was delineated by tetrazolium staining, and myocardial 5'-NT activities were measured by quantifying the release of adenosine from AMP. Despite comparable values of collateral blood flow in all groups, infarct size was reduced in preconditioned and MLA-treated dogs vs. controls. In addition, 5'-NT activities were increased throughout the heart with preconditioning and MLA treatment. However, single and multivariate regression analyses revealed no correlation between infarct size and 5'-NT activities for either treatment group. In fact, in the preconditioned cohort, animals with the highest enzyme activities developed the largest infarcts. This dissociation between infarct size and 5'-NT suggests that increased activity of 5'-NT is not the mechanism by which preconditioning or MLA treatment protects the canine heart against infarction.

5'-Nucleotidase↗
PubMed1996

[Changes of brain potentials related to visual attention during simulated weightlessness].

To study the possible effect of simulated weightlessness on brain function state, the brain event-related potentials (ERPs) during a simple visual selective response task were compared between head down tilt (HDT) and head up tilt (HUT) in 9 normal subjects. The results were: both the target (T) and non-target (NT) flash signals induced significant slow positive potentials which were supposed to be related to the attention activity; the amplitude of the positive potentials in the frontal regions decreased significantly especially for NT-ERPs during HDT as compared with that during HUT. The data provide new evidence indicating that the ability of brain response declined during simulated weightlessness and more attention should be paid to the study of brain function during space flight.

Attention↗
PubMed1996

Sequestration of inhaled particulate antigens by lung phagocytes. A mechanism for the effective inhibition of pulmonary cell-mediated immunity.

Dendritic cells (DCs) have emerged as the dominant antigen-presenting cells (APCs) of the lung, playing a vital role in the induction of cell-mediated immunity to inhaled antigens. We have previously demonstrated that an airway challenge with the soluble antigen hen egg lysozyme yields rapid acquisition of specific antigen-presenting cell activity by purified pulmonary DCs and a cell-mediated immune response in the lung upon secondary challenge. To examine how a particulate antigen leads to a cell-mediated response in vivo, graded concentrations of heat-killed Listeria (HKL) were injected intratracheally into Lewis rats. The bacteria were rapidly ingested by lung macrophages and polymorphonuclear leukocytes. The ability of purified pulmonary DCs pulsed in vivo by an airway challenge with HKL to subsequently stimulate HKL-specific responses ex vivo showed a threshold response, requiring a dose in excess of 10(9) organisms/rat. By contrast, all dosages of HKL yielded specific sensitization of lymphocytes in the draining bilar nodes. Pulmonary DCs purified from rats after a secondary in vivo airway challenge with HKL at day 14 were ineffective antigen-presenting cells except at high dosages of antigen. The generation of cell-mediated pulmonary inflammation paralleled the antigen-presenting cell activity of pulmonary DCs and was observed only at high antigen dosages. Hen egg lysozyme immobilized onto polystyrene beads and injected intratracheally yielded comparable results to those observed with HKL. We suggest that a pulmonary cellular immune response is generated to an inhaled particulate antigen when the protective phagocytic capacities of the lung are exceeded and antigen is able to interact directly with interstitial DCs. The diversion of particulate antigens by pulmonary phagocytes may help to limit undesirable pulmonary inflammation while allowing the generation of antigen-specific immune lymphocytes in vivo.

Animals↗
PubMed1996

Evaluation of the redox tolerance index on hepatic energy reserve of hepatitis B patients.

OBJECTIVE: To detect the redox tolerance index (RTI) for hepatic energy reserve. PATIENTS AND METHODS: 27 patients with chronic active hepatitis B (CAH) and 34 patients with post-hepatitis B liver cirrhosis (LC) were studied. RESULTS: The RTI was significantly lower in CAH and LC cases than in normal controls (P < 0.01). There was no difference between CAH and LC. The RTI of decompensated LC was significantly lower than that of the compensated LC (P < 0.05), indicating that there was no correlation between RTI and the parameters of routine liver functions. CONCLUSION: It is suggested that the RTI based on redox theory is effective and accurate in predicting hepatic energy reserve.

Adult↗
PubMed1996

[Ion-selective microelectrodes: principle and application of in vivo measurements of ionic concentrations in cochlear endolymph].

OBJECTIVE: To introduce the method of making neutral carrier ion-selective microelectrode and use it for in vivo measurement of ionic concentrations in cochloear endolymph. METHODS: GG-17 glass capillaries with 1.85 mm O.D. were rinsed extensively and dried in an oven. Two capillaries were parallelly connected and pulled with microelectrode puller to make a double-barreled micropipette. One barrel was back-filled with ion exchanger and internal reference solution, which served as ionic potential electrode, while the other barrel filled with 150 mmol/L KCL as reference electrode. Each barrel of microelectrode was connected to differential electrometer via Ag-AgCl wire and output was recorded on a three-channel recorder. Every ion-selective microelectrode was calibrated in a series of standard solutions to determine the required characteristics. Twenty healthy guinea pigs with normal hearing were anesthetized and were artificially respired through the tracheal canal after the intramuscular injection of suxamethonium chloride. The tympanic bulla was exposed and a double-barreled ion-selective electrode was inserted into the scala media through the round window and basilar membrane. The ionic potentials and endocochlear potentials (EP) were simultaneously recorded from the basal turn of the cochlea. Ionic concentrations were then calculated by Nicolsky-Eisenman equation. RESULTS: The concentrations of potassium, sodium and calcium ions in the cochlear endolymph were 146.3 +/- 11.8 mmol/L, 0.36 +/- 0.22 mmol/L and 16.2 +/- 5.7 micromol/L, respectively. CONCLUSIONS: The neutral carrier ion-selective microelectrode made with the above method is reliable and therefore can be used for accurately measuring the ionic concentrations of microenvironment in vivo continuously and transiently.

Animals↗
PubMed1996

[Histopathological and immunohistochemical studies on gliosarcoma].

Immunohistochemical staining of 5 gliosarcomas was performed. Neoplastic glial component stained positive by GFAP. Endothelial cells lining the lumina of glomeruloid vascular structures stained positively with both UEA-1 and FVIII/RAg antibodies. Mesenchymal cells of sarcomatous areas stained positively with SMSA antibody and presence of PDGFR. The staining results demonstrate that the sarcomatous component of gliosarcoma is of smooth muscle origin and suggest that the vascular smooth muscle hyperplasia is related to PDGF.

Aged↗
PubMed1996

Nitrite, N-nitroso compounds, and other analytes in physiological fluids in relation to precancerous gastric lesions.

Levels of gastric juice nitrite, several urinary N-nitroso compounds, and other analytes were examined among nearly 600 residents in an area of Shandong, China, where precancerous gastric lesions are common and rates of stomach cancer are among the world's highest. Gastric juice nitrite levels were considerably higher among those with gastric juice pH values above 2.4 versus below 2.4. Nitrite was detected more often and at higher levels among persons with later stage gastric lesions, especially when gastric pH was high. Of those with intestinal metaplasia, 17.5% had detectable levels of gastric nitrite, while this analyte was detected in only 7.2% of those with less advanced lesions. Relative to those with undetectable nitrite, the odds of intestinal metaplasia increased from 1.5 (95% confidence interval = 0.6-4.1) to 4.1 (95% confidence interval = 1.8-9.3) among those with low and high nitrite concentrations, respectively. Urinary acetaldehyde and formaldehyde levels also tended to be higher among those with more advanced pathology, particularly dysplasia. However, urinary excretion levels of total N-nitroso compounds and several nitrosamino acids differed little among those with chronic atrophic gastritis and intestinal metaplasia and dysplasia, consistent with findings from recent studies in the United Kingdom, France, and Colombia. The data from this high-risk population suggest that elevated levels of gastric nitrite, especially in a high pH environment, are associated with advanced precancerous gastric lesions, although specific N-nitroso compounds were not implicated.

Adult↗
PubMed1996

Helicobacter pylori antibodies in relation to precancerous gastric lesions in a high-risk Chinese population.

Helicobacter pylori infection is a major cause of gastritis and may be a key risk factor for stomach cancer, but its role in the process of gastric carcinogenesis is not well understood. Herein, we examine H. pylori prevalence in relation to demographic and lifestyle factors and to severity of precancerous lesions in an area of China with one of the highest rates of stomach cancer in the world. H. pylori serum IgG antibody positivity was assayed among 2646 adults, ages 35-64, participating in a population-based gastroscopic screening survey in the high-risk area. The prevalence of positivity was evaluated according to gastric histology, environmental and lifestyle variables determined by interviews during the screening, and level of serum pepsinogens. The odds of advanced precancerous lesions (intestinal metaplasia and dysplasia) of the stomach among those with antibody positivity were estimated by logistic regression. Seventy-two % of the population was H. pylori antibody-positive, with nonsignificant variation by sex, age, income, education, family size, and cigarette smoking habits. H. pylori positivity was higher among those who ate sour pancakes, a fermented indigenous staple that is a risk factor for gastric dysplasia and stomach cancer in this population. The prevalence of H. pylori varied most notably, however, with gastric pathology. The percent of H. pylori positivity increased from 55 to 60 to 87% among those with superficial (nonatrophic) gastritis, mild chronic atrophic gastritis, and severe chronic atrophic gastritis, respectively, before falling to 78% among those with intestinal metaplasia or dysplasia. H. pylori antibody positivity also was strongly correlated with serum pepsinogen concentrations, particularly pepsinogen II, but knowledge of H. pylori status did not markedly improve serological identification of advanced precancerous lesions above that provided by pepsinogen ratios alone. The findings suggest that H. pylori infection contributes to the process of gastric carcinogenesis, particularly during the early stages, in this high-risk area.

Adult↗
PubMed1996

[Study on the test and evaluation of the toxicity of the strains preparation of the different subspecies of Bacillus thuringiensis and on the research into its standardization].

In this paper using the preparation of Bacillus thuringiensis of USA standard sample-subsp. kurstaki HD-1-S-1980 (H3a3b) the toxicity to different subspecies preparations such as subsp. dendrolimus U strain(H4a4b), subsp. galleriae C88 strain (H5a5b) is tested and evaluated. And product's standardization is also researched. Comparing their toxicity to various test-insects between the standard sample prepared from U strain and USA, standard sample, the boilogical determined results are as follows: the toxicity of U strain standard sample is respectively 18666.6 IU/mg(test-insects: Dendrolimus punctatus, 2nd larva), 22956.5 IU/mg(test-insects: Plutella kylostella, 2nd larva). The above-mentioned toxicity evaluations are higher than that of 16000 IU/mg of USA standard sample. The comparison in susceptibility shows as follows: suscepticibility of plutella kylostella is stronger than that of Dendrolimus punctatus. The products from U strain and C88 strain are trial-produced in medium-scale. The product's toxicity to test-insect Dendrolimus punctatus is determined using USA standard sample. The results are obtained as follows the toxicity evaluation of U strain products is 36444.4 IU/mg; that of C88 strain products is 28521.7 IU/mg. The both are obviously higher than that of USA standard sample. This proves that different subspecies strain's toxicity to the same test-insect is with defference and it is an important way to raise product's toxicity by improving and optimizing process in production. The whole experiment shows it is feasible to rectify the evaluation of the toxicity of our country's present products using USA standard sample, Dendrolimus punctatus and Plutella kylostella as test-insets. And it is simple and convienient as well as save time and save effort to make statistical analysis in computer with Basic program. To do statistical and operational analysis using our designed basic programming by micro-computer is more accurate and repid than by caculator.

Animals↗
PubMed1996

[Preliminary investigation of Helicobacter pylori infection in Linqu County of Shandong province].

A preliminary epidemiological investigation of Helicobacter pylori (HP) infection was performed with 13C-urea breathing test for 218 residents at the age from 40 to 69 years in a high risk area of gatric cancer, Linqu County of Shandong province. Our results show an overall HP infection rate of 71.10%, or 69.49% for men and 73.00% for women. The HP infection rate in the group of serious chronic atrophic gastritis was significantly higher than that of mild chronic atrophic gatritis (P < 0.05). The HP positive group also has a higher rate of complaining about gastric discomfort than the HP negative group (P < 0.02).

Adult↗
PubMed1996

[Intellectual status of patents cerebral cysticercosis].

OBJECTIVE: To study the intellectual status of patients with cerebral cysticercosis with dementia evaluation scale. METHODS: The intellectual status of 112 patients with cerebral cysticercosis was studied with Hasagawa dementia evaluation scale and that of 30 patients with event related potential of P 300. RESULTS: In the patientsl, 50.9% suffered from mental dysfunction. Among them 11.6% had severe abnormality, 13.4% moderate, and 25.9% mild. Hypertension, epileptic attack and improper medication may cause intellectual dysfunction. CONCLUSIONS: Protection of mental function should be considered when chosing the treatment for better recovery of the patients. Hypertension, epileptic attack and improper medication may cause intellectual dysfunction.

Brain Diseases↗
PubMed1996

[Preoperative intraluminal 5-FU osmosis chemotherapy as an adjuvant to radical resection for rectal cancer].

Patients with rectal cancer of stage dukes B and C were randomized into two groups. In osmosis chemotherapy group 86 patients were treated by radical resection plus adjuvent preoperative intraluminal 5-FU osmosis chemotherapy at the area of tumor. In control group 74 patients were treated by radical resection alone. There were high concentration of 5-FU in the cancer, mucosa and lymph node around the cancer and mesenterica inferior venae, and the lower in a round venae. After the chemotherapy the symptoms were improved without side-effects, the II-III grade at pathological change was 83%, the cancer regression more than 50 was 38%. Compared the two groups osmosis chemotherapy raised 14% at radical resection and reduced 22%, 11%, 22% at local recurrence and metastasis of lymph nodes and liver. The 3-, 5-year survival rates (81.1%, 69.6%) were higher than 19.2%, 26.7% in the control group.

Adenocarcinoma↗
PubMed1996

[Enzyme kinetic studies on the in vitro metabolism of omeprazole by Chinese human liver microsomes].

In the present study, a specific and reliable method was developed for the determination of omeprazole and its two major metabolites, hydroxyomeprazole (OH-OPZ) and omeprazole sulfone (OPZ-SFN) in Chinese adult human liver microsome by reversed phase HPLC assay. Formation of these metabolites is linear for at least 60 min and between 0.25 and 1 mg.ml-1 of microsomal protein. The enzyme kinetic analysis of the reaction revealed that the hydroxylation Vmax and K(m) obtained with the human liver microsomal preparation were 42.9 nmol.min-1.(mg protein)-1 and 6.49 mumol.L-1, respectively. The maximum formation rates of OPZ-SFN (Vmax) was 6.63 nmol.min-1.(mg protein)-1, with a K(m) value of 11.8 mumol.L-1. A number of compounds were tested for their ability to inhibit OPZ metabolism. Our results showed that mephenytoin, diazepam and nordiazepam are competitive inhibitors and papaverine is an uncompetitive inhibitor of OPZ hydroxylation. These studies suggest that the same isozyme metabolising MP, DZ and NDZ (may be P450 2C or P450 3A) may be involved in the hydroxylation of OPZ. Moreover, the compounds tested also have some effects on the formation of OPZ-SFN in vitro with Chinese human liver microsomes.

Adult↗
PubMed1996

[Effects of electrical acupuncture on the cerebral blood flow and the pial microcirculatory blood flow in dogs].

Using electromagnetic flowmeter and Laser Coppler Microcirculatory flowmeter, we studied the effect of electrical acupuncture at Zusanli (ST 36) and Quchi (LI 11) on cerebral blood flow and pial microcirculatory blood flow in dogs. The results showed that the cerebral blood flow increased remarkably, while the cerebral vascular resistance (CUR) decreased 1 min. after the acupuncture start and 20, 30, 60, 90 min. after stopping of the stimulation, and the blood flow of the pial microvessels increased 1, 5, 10 min. after starting of acupuncture and 30 min. after stopping of the stimulation. It indicates that one of the mechanisms of treatment of cerebral vascular diseases with acupuncture is that acupuncture increases the cerebral blood flow and improve the pial microcirculation.

Animals↗
PubMed1996

[Hypolipidemic action of soy fiber and its effects on platelet aggregation and coagulation time in rats].

In order to lay a scientific basis for the development and use of soy bean, six per cent of soy fiber (SF) and pure cellulose were added to normal feed containing 1% of cholesterol and 0.2% bile salt, to feed SD rats, as compared with a control group of rats fed only with the normal feed, to study the effects of fibers on blood lipid concentration, platelet aggregation and clotting time. Results showed SF could not only significantly lower serum total cholesterol (TC), LDL-C and atherosclerotic index, and increase the ratio of HDL-L/TC, but also significantly lower serum fibrinogen (FB) and platelet aggregation, prolong clotting time (P < 0.01). NO such effects were observed in rats fed with pure cellulose. The authors believed that hypolipidemic effect of SF was achieved by lowering LDL-C in animals with hyperlipemia, and lowering of blood lipid and FB were major reasons to make animals fed with SF-added feed lower their platelet aggregation and prolong their clotting time.

Animals↗