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Biomedical subjects

J Chai

Publications and source records attributed to J Chai.

At least 91 records · Page 5Linked to original sources
PubMed1995

[Study on skin storage at -20 degrees C].

Small pieces of fresh guinea pig or cadaveric skin, 0.3mm in thickness, were soaked in cryoprotective solution for 30 min, then were put into plastic bags and kept in -20 degrees C refrigerator. Before and after 14, 30, 45, 60, 75 days storage, the skin were sent for succinae dehydrogenase assay (modified Hershey's method) and oxygen consumption determination (microelectrolyte method). The average viabilities measured by succinated dehydrogenase and oxygen consumption were nearly 50% after 60 days storage and 30% after 75 days storage in both guinea pig and cadaveric skin. 37 times of autologous skin stored at -20 degrees C for 1-26 days were grafted on the granulation wounds with good results. Skin can be preserved viably at -20 degrees C for 45 days but not longer than 60 days. This method may be helpful for hospital which has no -80 degrees C deep freezer or liquid nitrogen container.

Animals↗
PubMed1995

A study of mRNA expression of glucose transporter gene in rats with diabetes mellitus.

The study was proceeded on the mRNA expression of the GLUT-1 and GLUT-4 gene in the alloxan-induced diabetic rats by the method of dot-blot hybridization analysis. The results showed that the levels of the GLUT-4 mRNA expression were reduced in the muscle tissue of the diabetic rats while its levels in the same tissue of insulin treated diabetic rats increased. It was suggested that the reduced GLUT-4 mRNA expression which could affect its posttranslational products may be one of the causes of the insulin resistance.

Adipocytes↗
PubMed1995

[The characteristics of inhalation injury and pulmonary infection in burn patients and the influence on their mortality].

940 patients with thermal injury during the past 14 years were reviewed. Of them, inhalation injury was diagnosed in 75 patients, including 15 mild injury who all survived, 25 moderate injury, of whom 13 died with a mortality rate of 52.0% and 35 severe injury, of whom 31 died with a mortality rate of 88.6%. The data showed that 70% of burn that caused inhalation injury occurred in a closed space and 96% of which also caused facial injury. With the burn extent increasing, the incidence of inhalation injury and pulmonary infection rise correspondingly. The time and incidence of pulmonary infection in the patients with inhalation injury was earlier and higher than that in those without inhalation injury (P < 0.01). With similar burn area and age, the risk of death in the patients with inhalation injury was 17.2 times of the patients without inhalation injury (P < 0.001). Pulmonary infection further increased mortality of the patients (P < 0.001).

Adolescent↗
PubMed1995

[Studies on the molecular evolution of glucose transporter gene family].

Glucose transporter gene family which was involved in the glucose metabolism in the body has been considered as a candidate gene in the development of diabetes mellitus. We compared the nucleotide and amino acid sequences of the family in different species; deduced the hydrophilicity and hydrophobicity distribution of the amino acid; calculated the genetic distance and constructed the phylogenetic trees by UPGMA and N-J method. The results showed that the members of glucose transporter gene family are homologous; all the members of this family have a similar topology; It is suggested that the family may derived from a remote common ancester in which the gene duplication events of different origins took place; this evolutionary process is advantageous to the stability of the structure. The different branch length in the phylogenetic trees constructed by the N-J method indicated difference of evolutionary rates in the process of evolution. Also, the difference between the trees at protein and nucleotide level may result from the hidden substitution in the genome.

Animals↗
PubMed1994

The effect of a shear load on the viscosities of 10 vinyl polysiloxane impression materials.

The viscosities of 10 vinyl polysiloxane impression materials with and without the effect of a shear load were studied. Samples of each impression material were divided into two groups. An initial shear load of 5.12 rpm was applied to group A samples for 10 seconds. No shear load was applied to group B samples during the same interval of time. The viscosities of two groups of samples were compared at 60 seconds. Results indicated that there were statistically significant differences among the group A or B samples of the impression materials. There were no statistically significant differences between the group A and B samples of five impression materials. The group A samples displayed significantly lower viscosities than group B samples for two impression materials. The group A samples also displayed significantly higher viscosities than group B samples for three impression materials. It was concluded that the effect of a shear load had no consistent effect on the viscosities of a group of vinyl polysiloxane impression materials.

Analysis of Variance↗
PubMed1994

A comparison of the hardness of different types of titanium and conventional metal ceramics.

This study compared the surface hardness of machine milled titanium and cast titanium, and the surface hardness profile of a gold-palladium alloy, a nickel chromium alloy, milled and cast titanium. For each group, 15 discoid specimens, 10 mm in diameter and 5 mm thick, were fabricated by either casting or milling. Five specimens of each group underwent one of three treatments: (1) no heat treatment, (2) a standard heat treatment, or (3) an extended heat treatment. Knoop hardness values were determined. Results indicated that the Knoop hardness of cast titanium was less than that of the cast titanium standard treatment group, which was less than the Knoop hardness of the cast titanium extended treatment group. Knoop hardness of milled titanium was less than that of the milled titanium standard treatment and milled titanium extended treatment groups. For the surface hardness profile, cast titanium showed a decreasing surface hardness as the distance from the surface of the specimen increased. No such trend was identified for the other groups tested.

Chromium Alloys↗
PubMed1994

An investigation of the rheological properties of several interocclusal registration materials.

PURPOSE: To study the viscosities of eight interocclusal registration materials at 30 seconds after the start of mixing and to compare the time (Tcv) required for various interocclusal registration materials to reach a proposed critical viscosity of 5,000 poise. MATERIALS AND METHODS. One zinc-oxide eugenol, one polyether, and six vinyl-polysiloxane interocclusal registration materials were studied. The viscosities of the polymerizing materials were monitored with a cone and plate viscometer. RESULTS: One-way analysis of variance showed significant difference in the viscosity at 30 seconds and in the Tcv among the materials. A zinc oxide eugenol interocclusal registration material was found to possess the lowest viscosity at 30 seconds and the longest Tcv. CONCLUSIONS: The criteria for the selection of an interocclusal registration material should include its viscous properties because all materials behaved differently.

Analysis of Variance↗
PubMed1994

[Carcinoma arising from postburn scars (report of 5 cases)].

Carcinoma arising from postburn scars is rare. We have encountered 5 patients suffering from this late complication of scars, accounting for 0.32% of 1563 admissions for late surgery after burn injuries. They were all males, with a mean age of 56 years. The mean latent period was 43.2 years, and it was apparently longer when the acute burn injury occurred earlier in life. The site of predilection was the lower extremity, and multiple biopsies of various sites of the lesion remained to be the measure of confirmation. Pathologically, they were all squamoon cell carcinoma, grade I in 4 cases and grade II in 1. Immunohistochemical staining with anti-proliferation cell nuclear antigen (PCNA) showed that PCNA positive nuclei of squamous cell carcinoma were more numerous, as compared with that in the neighboring pseudo -epitheliomatous hyperplasia (PEH) and in normal skin, denoting markedly augmented assimilation of DNA in malignant degeneration. On the contrary, the number of Langerhan's cells were smallest in cancer area, as compared with PEH and normal skin. The diagnosis, treatment and prevention of such malignant degeneration in postburn scars have been discussed.

Adult↗
PubMed1994

[Studies on the molecular evolution of apolipoprotein multigene family].

The apolipoprotein genes represent a large family of genes encoding various binding proteins for plasma lipid transport. Because of their long divergence history, it is not known whether and how these genes have evolved through gene duplication from a common ancestor. To test this possibility and reconstruct a reliable phylogenetic tree, a simple method to evaluate the branch length and its divergence time in unrooted parsimony tree under the condition of non-even evolutionary rate was developed. The tree built from the 26 apolipoprotein sequences by above method clearly shows: (1) The common ancestor of ApoA-I ApoA-II, ApoA-IV, ApoE may appear 460 million years ago in an ordovician vertebrate which may be related with the major apolipoprotein LAL1 and LAL2 in Lamprey from the evidence of sequence alignment; (2) The central role of different selection pressure upon the ancestor gene of apolipoprotein made them evolved into different subgroups; (3) The high evolution rate in rodent ApoE molecules may be related with the existence of a large amount of hidden substitutions and the disruption of synonym codon usage clock in their genome; (4) The evolutionary rate of various branches in parsimony tree is significantly different in which the average UEP of ApoA-I, ApoA-IV is 2.0 MY, ApoA-II 1.7MY, ApoE 2.4MY; (5) The receptor domain in ApoE seems to be more conservative than other fragments. These data suggest a long, complex evolutionary history for apolipoprotein genes in which the gene duplication events of different origins took place.

Amino Acid Sequence↗
PubMed1993

Human renal carcinoma line transfected with interleukin-2 and/or interferon alpha gene(s): implications for live cancer vaccines.

BACKGROUND: Combination therapy with systemically administered interleukin-2 (IL-2) and interferon alpha (IFN-alpha) has resulted in long-term objective remissions in 30% of patients with metastatic renal cell carcinoma (RCC), but toxic effects are clinically significant. PURPOSE: We have thus investigated an alternative therapeutic approach--continuous intratumoral production of IL-2 and/or IFN-alpha by a cytokine-transfected human RCC tumor cell line. METHODS: Plasmid vectors were used to transfect the R11 RCC line with the genes for human IL-2 and/or IFN-alpha by the calcium phosphate precipitation method. Biologic characteristics of the cytokine-transfected tumor cells were determined by assays of thymidine incorporation and cytotoxicity, fluorescence-activated cell-sorter analysis, Northern blotting, and in vivo studies in C3Hf/Sed/Kam mice rendered T-cell deficient. RESULTS: The transfected cell lines produced the following amounts of cytokine per 10(6) cells per day: R11-IL-2 (220 U), R11-IFN-alpha (10,240 U), and R11-IL-2 + IFN-alpha (95 U + 1270 U, respectively). Gamma irradiation did not eliminate cytokine secretion. Morphology and growth rates were identical to those for the parental R11 cell line, except for IFN-alpha-producing clones, which showed significant growth inhibition. All cytokine-producing cells demonstrated increased susceptibility to cell killing by peripheral blood leukocytes (PBL). IFN-alpha producers exhibited enhanced HLA antigen expression and suppressed c-myc messenger RNA expression; when cocultured in vitro, they induced similar changes in parental R11 cells. IL-2 producers could stimulate growth and cytotoxicity of naive (i.e., freshly isolated, uncultured) and activated PBL. All cytokine-producing cells lost their tumorigenicity, as evidenced by failure to grow in the T-cell-depleted mice. When co-injected at a local site but not at a distant site, these cells prevented growth of parental R11 cells. Histologic examination of the injection sites revealed a substantial influx of macrophages. Intraperitoneal administration of IL-2 and/or IFN-alpha could not, however, prevent growth of the parental R11 tumors. CONCLUSION: Local production of high concentrations of IL-2 and IFN-alpha at the tumor site is more effective in preventing tumor growth than systemic administration. IMPLICATION: Continuous local delivery of cytokines via transfer of cytokine genes into tumor cells for use as live cancer vaccines is a novel strategy for manipulation of host-mediated antitumor immune response in patients with advanced RCC.

Animals↗
PubMed1993

An investigation of the rheological properties of 10 vinyl-polysiloxane impression materials.

PURPOSE: The time required for 10 vinyl-polysiloxane impression materials to reach a viscosity of 5000 poise (Tcv) was estimated. This viscosity was selected based on previous work that suggested that an impression material might not be workable if its viscosity exceeded this limit. The effect of variations in the time of placement of the impression materials into a simulated oral-temperature environment was also studied. MATERIALS AND METHODS: The change in the viscosity of the impression materials was recorded with a viscometer at oral temperature. Impression materials were placed at either 20 seconds, 30 seconds, or 40 seconds from the start of mixing. RESULTS: There were statistically significant differences in Tcv among various impression materials. Variations in placement time significantly affected the Tcv of six impression materials. CONCLUSIONS: Knowledge of the viscosity change of an impression material is beneficial in the clinical selection of an impression material.

Analysis of Variance↗
PubMed1992

Frequency distribution of Echinococcus granulosus hydatid cysts in sheep populations in the Xinjiang Uygur Autonomous Region, China.

Age-prevalence and age-intensity data of Echinococcus granulosus hydatid cysts in sheep populations were collected in an abattoir in the Xinjiang Uygur Autonomous Region, People's Republic of China. The frequency distribution of the larval cysts per sheep was empirically described by the negative binomial model, with parameter k being 0.5273. A mathematical model for the life cycle of E. granulosus was applied to the collected data and the results show that the infection pressure on sheep was 0.4362 (female) or 0.4119 (male) infections per year, the mean number of cysts increased linearly by 0.8824 (female) or 0.9971 (male) cysts every year and acquired immunity was too low to depress this rate of increase. According to certain definitions of steady states for taeniid populations, it was concluded that at least in some parts of Xinjiang, the life cycle of E. granulosus was and may still be in an endemic steady state. Consequently, the regular dog-dosing program would readily drive the infection from an endemic state towards extinction.

Age Factors↗
PubMed1992

Frequency distribution of Echinococcus granulosus in dog populations in the Xinjiang Uygur Autonomous Region, China.

Age-prevalence and age-intensity data of Echinococcus granulosus in dog populations were collected in four counties in the Xinjiang Uygur Autonomous Region, People's Republic of China. The frequency distribution of the parasite per dog was adequately described by the negative binomial model, with parameter k being 0.0571. The mathematical model of the life cycle of E. granulosus constructed by Roberts et al. (1986--Parasitology, Vol. 92, pages 621-641) was used to estimate the epidemiologic parameters of E. granulosus in Xinjiang. This model showed that the prevailing infection pressure on dogs was 0.4560 infectious insults year-1 and the mean length of an infection was 1.4975 years. The effect of acquired immunity on the prevalence of E. granulosus in dogs was considered to be insignificant.

Age Factors↗
PubMed1992

[Homology study of leptospires by molecular hybridization].

Nick translation and random primer labelling method were applied to prepare three genomic DNA probes from Leptospira interrogans strain 017, Leptospira biflexa strain Patoc I and Leptonema illini strain 3055, and then hybridized with DNA of 17 strains leptospires from different genus, species, serogroup and serovar. The results showed no homology between Leptospira and Leptonema, and only a low degree of homology between L. interrogans and L. biflexa but it showed a high degree of homology among L. interrogans. The study also proved the possibility to establish a DNA probe prepared from a single leptospira strain to detect different serovars.

Blotting, Southern↗