Biomedical subjects

J Gao

Publications and source records attributed to J Gao.

535 records · Page 30Linked to original sources

PubMedDate not supplied

Age-related decrease in brain synaptic membrane Ca2+-ATPase in F344/BNF1 rats.

We used Fisher 344/Brown Norway hybrid rats (F344/BNF1) to determine whether previously reported decreases in brain synaptic plasma membrane (SPM) Ca2+-ATPase activity in inbred F344 rats also occurred in the hybrids. Plasma membrane Ca2+-ATPase (PMCA) activity in SPMs from F344/BNF1 rat brains showed a progressive age-dependent decrease in Vmax from 60.9 +/- 3.7 nmol Pi/mg/min (n = 6) in 5-month rats to 32.4 +/- 3.6 nmol Pi/mg/min (n = 6) in 34-month animals, with no change in K (act) for Ca2+. Immunoreactive PMCA in SPMs also decreased by approximately 20% at 34 months, and the calmodulin (CaM) bound to membranes following extraction with EDTA also declined progressively with age. The effectiveness of CaM in stimulating PMCA activity was significantly lower when CaM was purified from the brains of old vs. young F344 rats and when CaM from 5-month rats was oxidized in vitro. These results indicate: 1) that PMCA activity in SPMs from longer lived F344/BNF1 hybrids also decreases with age; 2) that part of the reduction in PMCA activity is due to loss of PMCA from the membranes; and 3) that age-related structural changes in CaM may decrease its interaction with proteins in SPMs.

Aging↗

PubMedDate not supplied

Techniques for a structural analysis of dermatoscopic imagery.

Techniques were developed for automated detection and characterization of dermatoscopic structures, including the pigment network and brown globules. These techniques incorporate algorithms for grayscale shape extraction based on differential geometry developed by Steger, a snake algorithm, and a modification of the region competition strategy of Zhu and Yuille. A novel approach was developed for global segmentation of pigmented lesions, based on stabilized inverse diffusion equations. Procedures for detection of air bubbles and hairs in dermatoscopic images are also reported.

Air↗

PubMedDate not supplied

The extension of the range of NIM alanine/ESR dosimetric system to therapy level.

The NIM alanine/ESR dosimetric system, which was designed for industrial radiation processing, has been improved to be suited for applications in therapy dose range. Two different procedures of dose intercomparisons between IAEA and NIM were carried out with the improved system in the range of 2.5 to 100 Gy. In the first procedure, a set of NIM alanine dosimeters were irradiated at IAEA dosimetric laboratory and part of dosimeters marked "for evaluated" were evaluated using the rest of those with "known dose" given by IAEA. Most of evaluated doses agreed with IAEA doses within 1%. In the second procedure, all above dosimeters were evaluated on the base of NIM dosimetry. The results indicated that the doses determined by NIM agreed with those given by IAEA within 3% on the average.

Alanine↗

PubMedDate not supplied

Effect of oxygen supply on the suspension culture of genetically modified tobacco cells.

The effect of oxygen supply on the cultivation of the genetically modified tobacco cells and the formation of a foreign protein, beta-glucuronidase (GUS), was investigated in 250-mL Erlenmeyer flasks, a 5-L stirred tank fermenter, and a 7-L air-lift fermenter. The oxygen supply was varied by using different volumes of medium in the case of the 250-mL Erlenmeyer flask culture or by the different aeration rate in the case of the two types of fermenters tested. Higher oxygen supply stimulated cell growth and increased oxygen consumption rate, the level of phenolics, and GUS productions.

Cells, Cultured↗

PubMedDate not supplied

Air pollution and daily mortality in residential areas of Beijing, China.

The relationship between air pollution and daily mortality in 1989 was examined in two residential areas in Beijing, China. Very high concentrations of sulfur dioxide (SO2) (mean = 102 micrograms/m3, maximum = 630 micrograms/m3) and total suspended particulates (TSPs) (mean = 375 micrograms/m3, maximum = 1,003 micrograms/m3) were observed in these areas. Daily counts of deaths were regressed, using Poisson regression on the logarithm of (SO2) and/or TSPs controlling for effects of temperature, humidity, and day of week. A highly significant association was found between In(SO2) and daily mortality. The risk of total mortality was estimated to increase by 11% (95% confidence interval [95% CI] = 5%-16%) with each doubling in SO2 concentration. Separately, the association of In(TSP) with total daily mortality was positive but not significant (4% increase in mortality with each doubling in TSP; 95% CI = -2%-11%). When mortality was analyzed separately by cause, the association with a doubling in SO2 was significant for chronic obstructive pulmonary disease (29%), pulmonary heart disease (19%), and cardiovascular disease (11%), and marginally significant for the other nonmalignant causes (8%), but not statistically significant for cancer (2%). A similar association was noted for a doubling in TSP (4%, 38%, and 8% for total, chronic obstructive pulmonary disease, and pulmonary heart disease mortality, respectively), but the result was only statistically significant for chronic obstructive pulmonary disease. In the season-specific analysis, both SO2 and TSP were found to be significant predictors of total daily mortality in summer. In winter, SO2 was again significantly associated with increased mortality, but no positive association was found between TSP and mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗

PubMedDate not supplied

Comparison of theory and experiment in pulsatile flow in cat lung.

A mathematical model of pulsatile flow in cat lung based on existing morphometric and elastic data is presented and validated by experimental results. In the model, the pulmonary arteries and veins were treated as elastic tubes, whereas the pulmonary capillaries were treated as two-dimensional sheets. The macro- and microcirculatory vasculature was transformed into an analog electrical circuit. Input impedances of the pulmonary blood vessels of every order were calculated under normal physiological conditions. Pressure-flow relation of the whole lung was predicted theoretically. Experiments on isolated perfused cat lungs were carried out. The relation between pulsatile blood pressure and blood flow was measured. Comparison of the theoretically predicted input impedance spectra with those of the experimental results showed that the modulus spectra were well predicted, but significant differences existed in the phase angle spectra between the theoretical predictions and the experimental results. This latter discrepancy cannot be explained at present and needs to be further investigated.

Animals↗

PubMedDate not supplied

Long-term efficacy of recombinant interferon alpha 2a in the treatment of chronic hepatitis C: a randomized prospective study comparing two dose schedules in Chinese patients.

BACKGROUND/AIMS: This study is the first randomized prospective clinical trial of interferon in hepatitis to be conducted according to the guidelines of Good Clinical Practice (GCP) in China. The object of this study is to compare the long-term efficacy of a dose of 3MU of recombinant IFN alpha 2a (rIFN-alpha 2a) three times a week (t.i.w.) for 6 months with a starting dose of 6MU for 3 months and subsequent reduction to 3 MU t.i.w for a further 3 months. METHODOLOGY: Sixty-eight serological and histologically proven chronic hepatitis C patients with elevated serum ALT were randomized into two groups. A total of 63 patients were studied with full course of treatment. Five patients were withdrawn from the trial, 2 due to personal reasons and 3 due to adverse drug reactions during treatment. Thirty patients received 6MU IFN-alpha 2a t.i.w. for 3 months followed by 3MU t.i.w. for another 3 months (group A). Thirty-three patients received 3MU IFN-alpha 2a t.i.w. for 6 months (group B). RESULTS: The sex, age, baseline serum bilirubin, ALT and AST levels were matched in both groups. At the end of 6 months the complete and partial response rates in group A were 60.0% and 16.7%, respectively, and the clearance of serum HCV-RNA was 53.3%. In group B, the complete and partial response rates were 72.7% and 3.0%, respectively, and the clearance of HCV-RNA was 61.3%. These patients were followed up for 6, 12, and 18 months after stopping treatment. In group A, the rates of complete normalization of ALT and clearance of serum HCV-RNA at 24 months were 50.0% and 60.0%, respectively. In group B, the rates of normalization of ALT and clearance of HCV-RNA at 24 months were 54.4% and 41.9%, respectively. The efficacy between the two groups showed no statistically significant difference; the response rates of treatment were similar to the patients with HCV genotype 1b and 2a. Six patients (10.8% of the study population) developed neutralization antibodies to IFN-alpha 2a during treatment, 4 of them responded to the treatment. Adverse drug reactions (ADR) were common, but most of them were tolerable and the incidence of ADR was similar in both groups. CONCLUSIONS: IFN-alpha 2a is effective in the treatment of Chinese patients with chronic hepatitis C. The sustained response rates and ADR among two dose schedule groups are similar.

Adult↗

PubMedDate not supplied

Knowledge about tobacco and attitudes toward tobacco control: how different are smokers and nonsmokers?

Using data from a 1996 random-digit-dialing computer-assisted telephone survey of Ontario adults, 424 smokers and 1,340 nonsmokers were compared regarding knowledge about the health effects of tobacco use, attitudes toward restrictions on smoking and other tobacco control measures, and predictions of compliance with more restrictions. The response rate was 65%. Smokers were less knowledgeable than nonsmokers. Smokers were also less likely to support bans on smoking in specific locations, but majorities of both groups supported some restriction in most settings. Smokers were more likely than nonsmokers to predict that most smokers would comply with more restrictions, and more than three quarters indicated that they, themselves, would comply. Sizable proportions of both groups, especially smokers, failed to appreciate the effectiveness of taxation in reducing smoking. Support for other control measures also differed by smoking status. Both knowledge and smoking status were independently associated with support for more restrictions and other tobacco control policy measures.

Adolescent↗

PubMedDate not supplied

Mesenchymal stem cells and tissue engineering for orthopaedic surgery.

Bone marrow contains multipotent mesenchymal stem cells (MSCs) that can differentiate into different mesenchymal lineages whose end-stage cells fabricate bone, cartilage, tendon, fat, and other connective tissues. Our laboratory has been focusing on the purification, culture expansion, the in vivo and the in vitro characterization of MSCs and their descendants. Given the large number of MSCs that can be generated, we have explored their use in different pre-clinical models utilizing the therapeutic potentials of MSCs for musculoskeletal disorders. Using newly evolved tissue engineering principals, we have focus on the treatment of full thickness cartilage damage and, separately, bone non-union. The experimental results suggest the MSCs may provide a powerful therapeutic tool for the treatment of musculoskeletal disorders. Future efforts should be made to establish reliable and standardized full-scale clinical approaches using MSCs for orthopaedic surgery.

Animals↗

PubMedDate not supplied

Effect of oncogene transfection or passage in vivo on malignant phenotypes of rat2 cells.

Rat2 cells are thymidine kinase-deficient derivatives from the immortalized rat embryo cell line Rat1. They show no phenotypic correlates of malignancy in vitro and produce tumors in syngeneic Fischer rats after long latency periods. We have investigated how transfection with oncogenes would alter the in vitro and in vivo behavior of Rat2 cells. Thus we have manipulated Rat2 cultures in various ways. The cell lines obtained were categorized as parental, in vitro subclones, untransfected in vivo derivatives, non-oncogene (neor and tk) transfectants, oncogene (mutated c-Ha-ras, polyoma middle-T, FBR v-gag-fos-fox) transfectants, and in vivo derivatives of transfectants. They were tested in vitro for morphotype, colony formation in soft agar, growth in organ culture, invasion in organ culture, and in vivo for latency period of tumor formation, tumor growth rate, invasiveness, and metastasis. Differences between the consequences of various manipulations were found in the number of malignancy-related phenotypic alterations. The following trend could be deduced from our data: induction of invasiveness in organ culture by all manipulations; morphotypic transformation and shortening of tumor-latency period by all oncogene transfections and by passage with tumor formation in vivo; growth in organ culture and increased tumor growth rate in vivo by transfection with ras-, or fos-oncogenes and by passage in vivo. Metastatic capability (present in parental Rat2 cell tumors) and colony formation in soft agar (absent in Rat2 cells) were not affected by the present manipulations. We concluded that differences between the oncogene-transfectants and the untransfected in vivo derivatives do not lie in the expression of malignancy-related phenotypes but in the time needed to acquire them.

Animals↗

PubMedDate not supplied

The influence of fetal calf serum on interferon-gamma induced HLA-DR expression on U937 cells.

The induction of HLA-DR antigen expression on U937 cells by interferon-gamma (IFN-gamma) is positively influenced by amount of fetal calf serum (FCS) added to the tissue culture medium. A transient alkalinization of FCS before its addition to the medium, dramatically decreased the immunomodulating activity of IFN-gamma. FCS was also found to be a dose-dependent enhancer of the IFN-gamma-induced 2',5'-oligoadenylate (2-5A) synthetase production. Our findings suggest the need for a serum factor(s), labile at basic pH values, to support at least two of the multiple IFN-gamma activities.

2',5'-Oligoadenylate Synthetase↗

PubMedDate not supplied

The Chinese total diet study in 1990. Part I. Chemical contaminants.

The Chinese total diet study in 1990 estimated the dietary intake of 24 chemical contaminants and 72 nutrients from 4 market baskets collected and prepared in 12 provinces. Twelve food group composites were made for each regional market basket. The overall dietary Pb, Cd, Hg, hexachlorocyclohexane HCH, and DDT intakes were well below their corresponding acceptable daily intakes. However, the Pb content of eggs from the 2 southern regions exceeded the tolerance limit. The Hg content of legumes just reached the tolerance limit, and Hg in eggs from the North 1 region exceeded the tolerance limit. The dietary HCH intake has decreased significantly since the 1980s, but dietary DDT intake has decreased rather slowly. Five organophosphorus pesticides were detected out of a total of 12 organophosphorus pesticides analyzed. Among them, methamidophos was the most outstanding. The intake of total committed dose equivalents (CDEs) of the 6 radionuclides was 0.24 mSv/a; only 1.5% was accounted for by 90Sr and 137Cs. 210Pb, 210Po, 226Ra, and 228Ra accounted for 98.5% of the total CDEs. The main food sources of those radionuclides were cereals, vegetables, and aquatic foods. Aflatoxin B1 was detected at very low levels only in the cereal composite of the North 1 region. Aflatoxin M1 was not detected in any of the milk and milk products. The overall results show that there is no significant environmental contamination of the average Chinese diet.

Adult↗

PubMedDate not supplied

The Chinese total diet study in 1990. Part II. Nutrients.

This paper reports the intakes of 72 nutrients and their dietary sources obtained from the Chinese total diet study in 1990. Most of the nutrient intakes are close or equal to their corresponding recommended daily allowances (RDAs). Both the total energy intake (2203 kcal) and the proportions contributed by protein, fat, and carbohydrate meet the current Chinese RDAs and the World Health Organization (WHO) nutrient goals. The average protein intake was 64 g/day. The intake of essential amino acids all exceeded the Chinese RDA, and their proportions were generally consistent with the WHO recommended pattern. The average fat intake was 51.2 g/day (21.2% of the total energy intake). However, the dietary fat intake has been increasing significantly in the Chinese diet and the proportion of animal fat has reached 53% of the total fat intake. The total saturated:total monounsaturated: total polyunsaturated fatty acid ratio was 1.0:1.5:1.0. Although the average cholesterol intake was only 179 mg/day, it was 248 mg/day in the South 1 region. The intakes of thiamine and riboflavin were below the RDA. Retinol intakes in all the 4 regions were low. Most (80%) of the retinol (equivalent) intakes were from carotenoids. The average intake of total tocopherol was 89% of the RDA, and among the 4 regions, only the South 2 region has relatively low intake. The intakes of iron, copper, manganese, sodium, and phosphorus were adequate. The intakes of calcium, zinc, and potassium were insufficient, and intakes of selenium and magnesium were a little low. High sodium and low potassium intake is a traditional problem in the Chinese diet.

Adult↗