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Biomedical subjects

L Liu

Publications and source records attributed to L Liu.

At least 811 records · Page 45Linked to original sources
PubMed1997

In vivo salicylate hydroxylation: a potential biomarker for assessing acute ozone exposure and effects in humans.

Ozone is known to yield hydroxyl radical, which may contribute to ozone-mediated lung injury. In the presence of hydroxyl radical, salicylate is hydroxylated to form 2,3-dihydroxybenzoic acid (2,3-DHBA). There is no evidence of enzymatic formation of 2,3-DHBA. We hypothesized that salicylate hydroxylation might be used as a biomarker indicating human exposure to ozone. Healthy, nonsmoking volunteers, 18 to 34 yr of age, were given acetylsalicylic acid (975 mg) or placebo orally 0.5 h before an exposure. Subjects were exposed to ozone (0.12 or 0.4 ppm) or filtered air in an environmental chamber for 2 h, while performing intermittent exercise. Results indicate significant decrements in FVC, FEV1.0, forced expiratory flows at 50% and 75% of FVC, and peak expiratory flow rate, and an increase in airway resistance, after exposure to 0.4 ppm ozone in comparison with air control (p < 0.05). Exposure to 0.4 ppm ozone also resulted in increased symptom numbers and severity (p < 0.05). When subjects were exposed to 0.12 ppm ozone, changes of pulmonary function and symptoms reported were minimal. Plasma concentration of 2,3-DHBA was significantly increased after exposure to 0.12 and 0.4 ppm ozone in comparison with air control (p < 0.05). There was a significant correlation between ozone-induced changes of pulmonary function and normalized salicylate hydroxylation (p < 0.05). The results indicate that exposure to ozone can initiate in vivo production of hydroxyl radical, a potent reactive agent. Salicylate hydroxylation may then serve as a sensitive dosimetric biomarker for ozone exposure, even at subclinical ozone exposure levels.

Adolescent↗
PubMed1997

Conflicting bright light exposure during night shifts impedes circadian adaptation.

This simulated night shift field study compared high-intensity ("bright") light exposures designed to either facilitate or conflict with adaptation to a 9-h phase shift of the sleep/dark schedule. There were 7 days of baseline with night sleep followed by 8 night shifts with day sleep in a 2 x 2 design with factors bright light (facilitating vs. conflicting) and direction of shifted sleep/dark (delayed vs. advanced). A total of 32 subjects (8 in each group) were exposed to 3 h of bright light (about 5,000 lux) and 5 h of ordinary indoor room light of "dim" light (< 500 lux) during each 8-h night shift. The bright light was timed according to the light phase-response curve (PRC) to delay or advance rhythms; it was timed to occur either before or after the baseline body temperature minimum, which served as an estimate of the PRC crossover point between delays and advances. Core body temperature was measured continuously and demasked to determine daily temperature minima. Significantly more subjects showed large temperature rhythm phase shifts (> or = 6 h during the last 4 night shifts relative to baseline) with facilitating bright light compared to conflicting bright light as well as with delayed sleep/dark compared to advanced sleep/dark. The combination of facilitating bright light and delayed sleep/dark produced large phase delay shifts in all subjects tested. By contrast, the combination of conflicting bright light and advanced sleep/dark resulted in very small phase shifts in most subjects. Because bright light timed to delay usually was not able to phase shift rhythms when sleep/dark was advanced, it appears that the timing of sleep/dark was as important as the timing of the bright light. There was a relationship between the amount of phase shift and the individual's baseline phase when sleep/dark was delayed. Larger phase delays were achieved by subjects with later baseline temperature minima and greater eveningness on the Morningness-Eveningness Questionnaire. These results show that it is important to time bright light appropriately to achieve circadian adaptation to the night shift and that individual differences play an important role in the ability of the circadian system to phase shift.

Adaptation, Physiological↗
PubMed1997

Silencing of the gene for the alpha-subunit of human chorionic gonadotropin by the embryonic transcription factor Oct-3/4.

CG is required for maintenance of the corpus luteum during pregnancy in higher primates. As CG is a heterodimeric molecule, some form of coordinated control must be maintained over the transcription of its two subunit genes. We recently found that expression of human CG beta-subunit (hCGbeta) in JAr human choriocarcinoma cells was almost completely silenced by the embryonic transcription factor Oct-3/4, which bound to a unique ACAATAATCA octameric sequence in the hCGbeta gene promoter. Here we report that Oct-3/4 is also a potent inhibitor of hCG alpha-subunit (hCGalpha) expression in JAr cells. Oct-3/4 reduced human GH reporter expression from the -170 hCGalpha promoter in either the presence or absence of cAMP by about 70% in transient cotransfection assays, but had no effect on expression from either the -148 hCGalpha or the -99 hCGalpha promoter. Unexpectedly, no Oct-3/ 4-binding site was identified within the -170 to -148 region of the hCGalpha promoter, although one was found around position -115 by both methylation interference footprinting and electrophoretic mobility shift assays. Site-directed mutagenesis of this binding site destroyed the affinity of the promoter for Oct-3/4, but did not affect repression of the promoter. Therefore, inhibition of hCGalpha gene transcription by Oct-3/4 appears not to involve direct binding of this factor to the site responsible for silencing. When stably transfected into JAr cells, Oct-3/4 reduced the amounts of both endogenous hCGalpha mRNA and protein by 70-80%. Oct-3/4 is therefore capable of silencing both hCGalpha and hCGbeta gene expression. We suggest that as the trophoblast begins to form, reduction of Oct-3/4 expression permits the coordinated onset of transcription from the hCGalpha and hCGbeta genes.

Base Sequence↗
PubMed1997

[Clinical and pathological manifestations in 129 patients with tuberculous meningitis].

OBJECTIVE: To investigate the diagnosis of tuberculous meningitis. METHOD: One hundred twenty-nine cases of tuberculous meningitis proved by autopsy, from the year 1952 through 1994, were retrospectively reviewed. RESULTS: Sixty-four cases were misdiagnosed before death, and the misdiagnosis rate was 49.6%. Among these misdiagnosed cases, 34 were misdiagnosed as other brain diseases, and the other 30 cases were misdiagnosed as severe pulmonary tuberculosis, severe pneumonia, gastric cancer, rheumatic heart disease, cor pulmonale and leukemia, etc. The main clinical manifestations included meningitis and extra-cerebral tuberculous syndromes. The cerebral spinal fluid changes included pressure increase, elevation of cell counts and protein content, decrease of glucose and chlorides. Both cerebral CT and intensified scan showed miliary tubercles in the brain parenchyma. High density stellate type of shadows in the basal surface of the brain, interpedunclar forsa and cerebral fissures, enlargement of brain ventricles, cerebral edema and thrombosis were also shown. Tuberculous lesions in the meninges, brain parenchyma, brain ventricles and brain blood vessels were found by autopsy. CONCLUSION: The clinical manifestations, cerebral spinal fluid examination, in combination with CT scan of the head, and searching for extracerebral tuberculous foci are the basis for the diagnosis of tuberculous meningitis.

Adolescent↗
PubMed1997

Predictive value of clinic blood pressure variability for pressure changes during placebo in elderly hypertensives.

OBJECTIVES: Syst-China is the ongoing placebo-controlled double-blind outcome trial in older (aged 60 years or more) Chinese patients with isolated systolic hypertension (systolic blood pressure 160-219 mmHg and diastolic blood pressure < 95 mmHg). This article is based on the data accumulated until 31 August 1992. Its purpose is to investigate the extent to which the variability in the clinic blood pressure readings at baseline could predict the blood pressure changes observed in the placebo arm of the trial. METHODS: From 2379 patients recruited into the trial, 728 [455 men and 273 women, aged 66.7+/-5.5 years (mean +/- SD)] were selected, because their blood pressure readings for the three run-in visits as well as 3, 6 and 12 months after random allocation were available. Overall and between-visit blood pressure variabilities at baseline were estimated from the two readings obtained with the subject seated during the first and second run-in visits. The baseline blood pressure used to calculate the blood pressure changes during follow-up was the average of the two readings during the third run-in visit. RESULTS: The blood pressure variability at baseline was larger for women than it was for men. For all of the subjects combined, the blood pressure had decreased by 4.1+/-14.4 mmHg (P < 0.001) systolic and 0.5+/-6.7 mmHg (P < 0.06) diastolic by the 3-month follow-up visit, by 8.5+/- 15.2 and 1.4+/-7.5 mmHg, respectively, after 6 months and by 10.3+/-15.7 and 1.9+/-7.9 mmHg, respectively, after 1 year (p < 0.001 for all). Stepwise multiple regression analysis showed that sex, age, alcohol intake and the blood pressure at baseline were significant determinants of the long-term (1 year) blood pressure changes. Aftger adjustment for the aforementioned covariates, the between-visit variability was a significant predictor of the changes in the diastolic blood pressure after 1 year of placebo treatment for the men (partial r+/-SEM -0.36+/-0.12, P < 0.01) and for all of the subjects (-0.19+/-0.09, P < 0.05). For men, the partial regression coefficient between the overall variability and the changes in the diastolic blood pressure also attained statistical significance (-0.39+/- 0.14, P < 0.01). CONCLUSION: For older Chinese patients with isolated systolic hypertension, in particular for men, a higher blood pressure variability at baseline was associated with a larger decrease in diastolic blood pressure during 1-year follow-up on placebo, explaining up to 2% of the variance of the observed changes. Similar associations were not observed for systolic blood pressure.

Journal Article↗
PubMed1997

[Somatostatin in NRM plays roles in inducing analgesia and enhancing electroacupuncture analgesia].

The effects of microinjection of somatostatin (SS), somatostatin depletor cysteamine (CS) and anti-somatostatin serum (ASSS) on the pain threshold (PT) and electroacupuncture (EA) analgesia were investigated in the rat. The potassium iontophoresis induced tail-flick was used to measure the pain threshold. The "Zusanli" were stimulated with EA. The results indicated that microinjection of SS into necleus raphe magnus (NRM), could elevate PT and enhance EA analgesia. PT and EA analgesia were decreased when SS in NRM was depleted by CS or neutralized by ASSS. These data revealed that SS in NRM plays important roles in inducing analgesia and enhancing electroacupuncture analgesia.

Acupuncture Analgesia↗
PubMed1997

[A preliminary ultrasound biomicroscopic study of anterior segment structures in normal human eyes].

OBJECTIVE: We investigated anterior segment structures in normal human eyes by ultrasound biomicroscopy (UBM). METHOD: UBM high frequency transducer (50-100mHz) was used to measure the anterior segment of normal human eyes. RESULT: Cornea, sclera, iris, lens, ciliary body, anterior chamber, posterior chamber and extraocular muscles can be visualized by UBM. CONCLUSION: UBM is a new noninvasive method for imaging the anterior segment structures under living condition, and supplementary to the present existing imaging methods that have shortcomings in dynamic observation of the anterior ocular structures under such condition. As the frequency of the transducer is rather high, the imaging depth is limited to 4-5 mm, thus only the anterior ocular structures can be viewed.

Adult↗
PubMed1997

[Study on antitumor drug-induced apoptosis in human cancer cells by terminal deoxynucleotidyl transferase assay].

OBJECTIVE: Considerable evidence has showed that apoptosis is involved in both cancer development and inhibition. A new assay (terminal deoxynucleotidyl transferase assay, TdT assay) was recently reported to have advantages in the detection of apoptosis. In this study, this assay was used to investigate antitumor drug-induced apoptosis in human cancer cells. METHODS: TdT assay, DNA gel electrophoresis, electron and light microscopy were used to observe apoptosis. RESULTS: Our results showed that cisplatin-induced apoptosis in both HL-60 and SV40T-transformed human bronchial epithelial cells was detected with a good dose and time response. The occurrence of the apoptosis was preceded by the decrease of bcl-2 mRNA expression. With TdT assay, apoptotic cells were observed in the ovarian tumor of patients treated with carboplatin. CONCLUSION: TdT assay may be applicable to moniter apoptosis in human cancers induced by chemotherapy, and to evaluate tumor cell response during treatment.

Antineoplastic Agents↗
PubMed1997

[Preliminary study on erythrocyte immunity during sensorineural hearing loss of unknown etiology].

Red cell immune function was determined in 50 patients with sensorineural deafness and 30 healthy persons as control. The results showed that in patients with sensorineural deafness, the red cell C3b receptor (RBC-C3bR) rosette formation rate (15.10 +/- 1.66) was lowered markedly than controls (18.95 +/- 1.16, P < 0.001) and the red cell surface immune complex (RBC-IC 9.94 +/- 1.68) was elevated markedly than controls (7.44 +/- 1.17, P < 0.001). The results indicate that the red cell immunity in the patients with sensorineural deafness of unknown etiology is lowered.

Adolescent↗
PubMed1997

[Treatment of hard seeds of some plants with sulphuric acid].

By soaking seed in sulphuric acid, the hard seeds of some medicinal plants featuring low germination rate can be softened so as to acclerate the germination. Some relevant physiological processes are analysed in this paper. The study provides a theoretical basis for the artificial raising of medicinal plants in the field.

Fabaceae↗
PubMed1997

[A comparative study of application of PCR technique and Porphyromonas gingivalis nucleic acid probe in clinical examination of apical periodontitis].

By PCR technique and Pg nucleic acid probe, the authors investigated the Pg distribution in root canal samples from patients with clinical apical periodontitis and made a comparative study of the two methods. The results showed that: 1. Pg positive rate of apical periodontitis samples by PCR examination was 74% and that of by nucleic acid probe examination was 76%, and their total coincidence rate reached 94%; 2. between comparative groups there was no significant difference (P > 0.05) in all data by two examination methods; 3. Pg was closely related with clinical symptoms of apical periodontitis such as spontaneous pain, percussion pain, fetidity and periapical abscess. This indicates that the two methods are accurate, quick and convenient and can both be used in direct examination of clinical samples.

Adolescent↗
PubMed1997

[A preliminary study on preparing chromosome of young cotyledon from Sophora flavescens].

The present paper reports the experimental results on the preparing somatic chromosome of young cotyledon from Sophora flavescens, compared with root tip, the mitotic index of cells in cotyledon is higher, hydrolyze with enzyme and wall degradation are easely made, as the experimental material, the young cotyledon is more comeniently prepared.

Cell Division↗
PubMed1997

[The prospective study of the influence of cytomegalovirus (CMV) infection of pregnant women to fetus].

Screening of CMV infection in 450 pregnant women in Shenyang was carried on by ELISA and PCR methods, and CMV infection was detected in 100 of their infants prospectively. The results were 97.11% of pregnant women with past infection, 0.89% with primary infection, 11.11% with recurrent infection, only 2% were susceptible. From 450 pregnant women, there were 3 infants with congenital defects and 3 abortions in active infective group, who were positive for IgM antibody, CMV DNA were positive in heparin peripheral blood, cervical secretion, placenta or amnionic fluid. The fetal infection rate and congenital defect rate in infective group were higher than that in inactive control group. Within 100 maternal-infant pair group, congenitally infected infants were 1.43 times higher in infective group than that in control group (RR = 1.43). Two infants with mental retardations (MDI<70) were born in infective group, but none in control group. In our study, primary infection of early pregnancy was most harmful to fetus, the intrauterine transmission rate was 33.3%. Among nine infected infants born from the infective group, two infants were with CID, and seven were symptomless. CMV screening is important for pregnant women in view of eugenic. When active CMV infection is found in early pregnancy, termination of pregnancy is better considered while CMV detection of amniotic fluid is also positive.

Adult↗
PubMed1997

[High expression of human thrombopoietin mutant fusion protein in E. coli].

OBJECTIVE: To obtain human thrombopoietin (Tpo)mutant cDNA encoding mature peptide N terminal 1 approximately 196 amino acids and investigate its expression in E. coli JM109. METHODS: Polymerase chain reaction and DNA recombination techniques were employed. PCR product was inserted into pUC19 vector and sequenced and then cloned into expression vector pMAL-c2. RESULTS: E. coli JM109 cells with plasmid pMAL -MBP/TpoM were induced by IPTG for 4-5 hours. SDS-PAGE analysis showed that MBP/TpoM molecular weight is about 63KD. Scanning analysis indicated that expressed protein accounts up to 37% of total E. coli proteins. CONCLUSION: The Tpo mutant of interest is successfully expressed in E. coli JM109 cells.

DNA, Complementary↗
PubMed1997

[Effects of cytokines on multidrug-resistance in K562/A02 cells].

OBJECTIVE: To explore the effects of cytokines on human leukemic cell line K562/S and its multidrug-resistant counterpart K562/A02. METHODS: The toxicities of cytokines and the IC50 (the concentration causing 50% inhibition of cell growth) of DNR were assayed by MTT method; intracellular drug concentration was measured by fluorometry; p-glycoprotein (p-gp) expression was detected by APAAP and mdr-1 mRNA was assayed by RT-PCR. RESULTS: The IC50 of DNR for K562/A02 and K562/S cells were 45.08 microg/ml and 0.607 microg/ml, respectively. Pretreating K562/A02 cells with rhu IFN (500 U/ml) or rhu IL-2 (250 U/ml) for 24 hours partially restored the sensitivity of K562/A02 cells to DNR (IC50 were 16.39 and 11.96 microg/ml, respectively) but had not effect on K562/S cells, and it elevated the intracellular DNR accumulation in K562/A02 from 2151 ng/mg x protein to 2570 and 2503ng/mg x protein, respectively. p-gp and mdr-1 mRNA were not down regulated. By contrast, rhu G-CSF and rhu GM-CSF had no effect on either K562/A02 or K562/S. CONCLUSION: rhu IFN or rhu IL-2 could partially restore the sensitivity of K562/A02 to DNR and elevate the intracellular DNR accumulation via a mechanism independent of p-gp or mdr-1 mRNA down-regulation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

[The effect of smoking and passive smoking on thiocyanate content in saliva].

The saliva thiocyanate contents were determined among smokers and passive smokers. The saliva thiocyanate contents of passive smokers in smoking environment and non-smoking environment were compared. The results showed that the saliva thiocyanate in smoking environment was higher than that in non-smoking environment (P<0.01). The results indicate that the saliva thiocyanate detecting is a direct and sensitive index for evaluating the hazard of passive smoking.

Environmental Exposure↗