Search PubMed⌕ Search

Biomedical subjects

Y Yan

Publications and source records attributed to Y Yan.

At least 217 records · Page 12Linked to original sources
PubMed1998

[The factors affecting apoptosis by in situ terminal deoxynucleotide transferase method].

Apoptosis in biopsies of patients with hepatocirrhosis or hepatocellular carcinoma and in small intestinal mucosa of mice were detected by the method of in situ terminal deoxynucleotide transferase (ISTdT). It was found that the best positive result might be obtained by digesting tissue sections with 25mg x L-1 proteinase K for 15 minutes, then treating sections with moderate degree of microwave for 5 minutes after reaction with terminal deoxynucleotide transferase. The best choice of above conditions were discussed.

Animals↗
PubMed1998

[Alterations of amino acids in rat cerebral cortex of infectious brain injuries].

Concentrations of amino acids such as glutamate(Glu), glutamine(Gln), gamma-aminobutyric (GABA), glycerin(Gly) in rat cerebral cortex were measured by o-phthaldialdehyde method to clarify alterations of these amino acids in infectious brain injuries(IBI). The results were that Gln and GABA in groups treated by bordetella pertussis suspension(BP) 4h were increased compared to those in the group treated by the normal saline(NS) or the operative control(OC) and a positive correlation with water content or Evans blue content, respectively. In the 24h BP group, Gln was still increased; GABA and Gly were decreased compared to those in the NS or OC group. The findings suggest that GLu, Gln, and Gly play an important role and GABA may be a marker of injury in pathogenetic mechanism of IBI induced by BP.

Animals↗
PubMed1998

[Preliminary study on bone loss rate in early and late stages of post-menopausal women].

OBJECTIVES: To investigate the characteristics of bone loss rate and bone turnover in early and late stages of normal chinese postmenopausal women, and to evaluate the predictive value of bone biochemical markers. METHODS: Thirty-two early postmenopausal women (1-3 years after menopause, group 1) and 33 late ones (15-30 years after menopause, group 2) were enrolled. Serum and bone alkaline phosphotase (alkaline phosphotase, ALP; bone alkaline phosphotase, BAP), fasting uriuary calcium/creatinine ratio (Ca/Cr), and Pyridinoline/creatinine ratio (Pyd/Cr), serum osteocalcin(BGP), bone mineral density (BMD) were measured at laseline and 6 months, 12 month follow-up. RESULTS: In group 1, mean lumber mineral density decreased 1.3% and 2.6% at 6 and 12 month follow-up as compared with initial values, In group 2, bone loss rates of femoral neck and Ward's triangle were 1.3%, 5.3% at 6 months, and 1.9%, 4.6% at 12 months respectively. Urinary Pyd/Cr elevated with time in the two groups. Changes of BGP, BAP in the two groups were similar. There were positive correlations between ALP, Ca/Cr, BGP, BAP and BMD. No correlation was found between bone loss rate of lumber spine and biochemical markers. CONCLUSION: Lumber spine was the favorable site to assess rapid bone loss in early postmenopausal women. Femoral neck and Ward's triangle region were superior to other site in predicting slow bone loss. Bone turnover of the two groups were all accelerated. Single measurement of biochemical marker failed to predict bone loss rate.

Age Factors↗
PubMed1998

[The effect of HCV NS3 protein on expression of p53 gene protein in hepatocarcinogenesis].

OBJECTIVE: To investigate hepatocarcinogenesis by detecting the effect of HCV NS3 protein on expression of P53 protein in hepatocellular carcinoma (HCC) and pericarcinomatous liver tissue. METHODS: The expression of HCV NS3 and P53 protein was detected by immuno-histochemical technique (SP method) in specimens of HCC and their surrounding liver tissues from 47 patients with negative HBV. RESULTS: The positive rate of HCV NS3 protein was lower in HCC(62%) than in pericarcinomatous liver tissue(83%) (P < 0.025). The expressive strength of HCV NS3 protein in HCC was related to the degree of carcinomatous cell differentiation(P < 0.025). The positive rate of P53 protein in carcinomatous tissue(81%) was higher than in pericarcinomatous liver tissue (47%)(P < 0.025). The worse differentiation of cancer cells, the stronger expression of P53 protein (P < 0.05). The expression of P53 protein was not correlated with the expression of HCV NS3 protein in carcinomatous tissiue (P > 0.5), whereas their expression was closely related in pericarcinomatous liver tissue(P < 0.01), and the expressive rate of P53 protein in the cases of positive HCV NS3 protein was higher than that in the cases of negative HCV NS3 protein. CONCLUSION: HCV NS3 protein may exert its hepatocarcinogenic effect in early stage on host cells by endogenous pathway which may bring about mutation of p53 gene and transformation of hepatocytes.

Carcinoma, Hepatocellular↗
PubMed1998

[Distribution of transforming growth factor-beta and its receptor in bronchiolo-alveolar cell hyperplasia and bronchiolo-alveolar carcinoma].

The distribution of the three isoforms of transforming growth factor (TGF)-beta (TGF-beta 1, -beta 2, and -beta 3) as well as their signaling receptor, TGF-beta type I receptor (T beta R-I), in bronchiolo-alveolar cell hyperplasia (BAH) and bronchiolo-alveolar carcinoma (BAC) was examined by immunohistochemistry using specific antibodies. The results showed that the expression of one or more TGF-beta subtypes occurred in a large proportion of BAC and BAH tissues. The expression of TGF-beta 1 and TGF-beta 3 was increased in tumor cells compared with hyperplastic cells. BAC with expression of two or three ligands was associated with a higher incidence of lymph node metastasis. These results suggest that hyperplastic cells and cancer cells derived from bronchiolo-alveolar cell can synthesize and secrete TGF-beta isoforms and its receptor T beta R-I which may contribute to the progression of BAC in part.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1998

[Estimation of cytosolic free calcium within synaptosomes with fluorescene indicator Fura-2].

Intracellular free calcium [Ca2+]i concentration has become a focus of attention for investigators in the field of brain edema. It is the purpose of the present study that the changes of the concentration of the free calcium within cortical neurons were investigated on the model of brain edema induced by freezing injury. [Ca2+]i was determined in calcium fluorescent indicator Fura-2/AM loaded neuronal synaptosomes by using mono-wave length spectrofluorophotometer. The method for preparing synaptosomes, and the method and mechanism of concentration of cytosolic free calcium using fluorescent indicator Fura-2/AM were studied.

Animals↗
PubMed1998

Effects of combined radiation and thermal burn injury on the survival of skin allograft and immune function in rats.

OBJECTIVES: To investigate the effects of combined radiation and thermal burn injury on the survival of skin allografts and to analyze the relationship between the prolongation of allograft survival and the changes of immune functions of the thymocytes and splenocytes in rats. METHODS: Wistar rats were irradiated with 3, 4, 5, 6 and 8 Gy of gamma rays. Thirty minutes after radiation, 15% TBSA III-degree burn was inflicted to the rats. Twenty-four hours after the burn injury, allografts were used to cover the burn wounds. In the 8 Gy group, 1 hour before skin grafting, the bone marrow cells (4 x 10(8)) from the same donor were also transplanted. All rats were carefully observed after injury. The rats with single radiation injury of 5 Gy gamma rays, with single burn injury and with combined radiation-burn injury were killed 3, 7, 10, 15 and 30 days after skin grafting for immunological assay and pathological study. RESULTS: All the allografts in the single burn group were rejected in 10 days. In the combined injury groups, the survival rates of the allografts in rats undergoing 3 and 4 Gy radiation were 20% and 30%, respectively. In the combined injury groups undergoing 5, 6 and 8 Gy radiation, the 10-day survival rates of the allografts were 69%, 88% and 100% respectively, and the 30-day survival rates in the three groups were 36%, 42% and 100% separately. The grafted allogenic skin, with normal epithelial cells and good vascularity, healed well with the recipient's skin. Hairs grew well from the allografts 30 days after grafting. Three, 7 and 15 days after allografting, in the single burn group, the proliferative activities of the thymocytes were 90%, 185% and 130% of the preinjury level, and the antibody forming capacities of the splenocytes were 200%, 171% and 300% of the preinjury level, respectively; in the combined injury groups, the proliferative activities were 6%, 99% and 91% of the preinjury level, and the forming capacities were 2%, 36% and 90% of the preinjury level. CONCLUSIONS: The survival rate of allograft in rats undergoing combined radiation and thermal burn injury rises with the increase in radiation dosage. The allograft covering single bun injury is severely rejected by immune reaction. The prolongation of the survival of allograft in combined injury group mainly results from radiation that suppresses immune functions.

Animals↗
PubMed1998

[Effect of hypoxia on proliferation and alpha 1 (I) procollagen gene expression by human fetal lung fibroblasts].

OBJECTIVE: The effect of 2% hypoxia on the proliferation and alpha 1(I) procollagen gene expression by human fetal lung fibroblast was studied. METHODS: Cell proliferation was determined by cell counting and nonradioactive cell proliferation assay method. alpha 1(I) procollagen gene expression was detected by Northern blot hybridization analysis. RESULTS: Cell number and 490 nm OD expressing low oxygen values were markedly increased by the 24, 48 and 72 h exposure to 2% hypoxia respectively. An obvious increase of the alpha 1(I) procollagen mRNA expression was detected after 24 h exposure to 2% hypoxia. The increase of gene expression could be inhibited by Ligustrazin (30 micrograms/ml, 10 micrograms/ml). CONCLUSIONS: 2% hypoxia plays an important role in the outcome of wound healing and pulmonary vascular remodeling by affecting the function of human fetal lung fibroblasts.

Cell Division↗
PubMed1998

[A research on chemical dynamic changes and drug efficacy of SMS compound prescription: chemical researches on shenmaisan prescription (I)].

To clarify the material base of the distinct curative effect of Shengmaisan (SMS) compound prescription, a study was made on the dynamics of chemical constituents in the decoction prepared according to the compound prescription. From the decoction a new compound was isolated and identified by UV, IR, MS and NMR as 5-hydroxymethy-2-furaldehyde (5-HMF). The study suggests that the distinct curative effect of SMS compound prescription hinges on a material base which is different chemically from that in the other three single drugs used separately, thus presenting scientific criteria for rational compatibility and quality check in making preparations on compound prescriptions.

Drug Combinations↗
PubMed1998

[Infrared spectra of Caulis Mahoniae and 6 species of medicinal plants of the same genus].

Based on the IR spectra of the petroleum ether extract, ethyl ether extract and water extract of Caulis Mahoniae and six species of medicinal plants of the same genus, it has been found out that the differences of chemical constituents among the samples can be reflected by the changes of IR spectra. This method can be used as a rapid and exact means to search unknown species with same chemical constituents in the same genus and family.

Drug Contamination↗
PubMed1998

[A research on chemical dynamic changes and drug efficacy of shengmaisan compound prescription: chemical researches on shengmaisan prescription(II)].

The content changes of 5-hydroxymethyl-2-furaldehyde(5-HMF), a new compound reported in the previous paper, in eight prescriptions of different composition were further determined by HPLC with a view to find the chemical dynamic changes and compatibility of medicines. The contents of 5-HMF in different combinations of Radix Ophiopogonis and Fructus Schisandrae, different boiling times and boiling frequency were examined. The results indicated that 5-HMF was produced in the boiling process of Radix Ophiopogonis and Fructus Schisandra combined. The contents of 5-HMF would increase with the increase of Radix Ophiopogonis amount, reaching the highest value after 1.5 h boiling and two times of boiling.

Drug Combinations↗
PubMed1998

[The study of presurgical and postsurgical orthodontic treatment of alveolar bone grafting on patients with complete cleft lip and palate].

OBJECTIVE: To investigate the patients who need the orthodontic treatment before and after alveolar bone grafting; the selection of the indications and so on. METHODS: To select 20 patients with cleft lip and palate, each of them is treated by edgewise appliance, light-wire appliance or removable appliance half to one year before the operation. RESULTS: After orthodontic treatment, the patients' maxillary teeth are drawn up in order; the distorted teeth have the right positions; the shape of the arch is normal and the teeth beside the cleft are no longer oblique. All of these give a good space to the grafted bone. CONCLUSION: The orthodontic treatment before and after alveolar bone grafting is an important composition of serial treatment of cleft lip and palate. It not only gives a promise to the successful operation, but also makes patient a better shape and function of the occlusion.

Alveolar Process↗
PubMed1998

[The diagnosis and treatment of primary carcinoma of the duodenum].

OBJECTIVE: To improve the diagnosis and treatment of primary duodenal carcinoma. METHOD: The records of 18 patients with primary carcinoma of the duodenum were reviewed. RESULT: 7 cases underwent pancreatoduodenectomy: segmental duodenectomy (1), intraoperative death (1), survived 3 years (2), and survived 5 years after operation (3). 7 cases underwent gastroenterostomy or cholangioenterostomy; they died in 11 months after operation. Three cases who received biopsy only died in six months after operation. CONCLUSION: The understanding of duodenal carcinoma is the key factor for early diagnosis. The appropriate examinations are necessary for suspected patients. Once the diagnosis is confirmed, the result of surgical treatment is improved.

Adult↗
PubMed1998

[Relationship between changes of phospholipid and lipid peroxide of erythrocyte membrane and diabetic retinopathy].

OBJECTIVE: To study the relation between the changes of phospholipid and lipid peroxide (LPD) in erythrocyte membrane in diabetes mellitus with the occurrence of diabetic retinopathy (DR). METHODS: The levels of triglyceride (TG), cholesterol (TC), glycosylated hemoglobin (HbA(1)c), phosphatidylethanolamine (PE), phosphatidylinostiol (PI), phosphatidylserine (PS), phosphatidylcholine (PC), sphingomyelin (SM), lysophosphatidylcholine (LPC), lipid peroxide (LPO) and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were investigated in 44 diabetic patients with DR, 20 diabetic patients with no DR (NDR) and 30 sex and age matched normal control subjects. RESULTS: A significant decrease in PE, PI, PS, PC, SM, SOD and GSH-PX and a significant increase in LPC, LPO, TG, TC and HbA(1)c were detected in DR and NDR group when compared with the normal controls. These changes were more obvious in DR group. CONCLUSION: The lipid peroxidation and the alteration of the erythrocyte membrane phospholipid compositions may contribute to the occurrence and development of DR.

Adult↗
PubMed1998

[Residue of sodium hyaluronate in aqueous humor following intraocular lens implantation].

OBJECTIVE: To determine the residue of sodium hyaluronate in aqueous humor following intraocular lens (IOL) implantation. METHODS: The percentage concentration of sodium hyaluronate in aqueous humor in 23 patients (25 eyes) having undergone IOL implantation was measured by Shimadzu UV-3101 ultraviolet spectrophotometer before and after irrigation with BSS 2 ml, 5 ml and 8 ml. RESULTS: The different percentage concentrations of sodium hyaluronate were 65.50% +/- 18.12%, 10.20% +/- 4.80%, 2.19% +/- 1.83% and 0.70% +/- 0.91%. CONCLUSION: Replacement of aqueous humor by BSS 2 ml can eliminate the most part of sodium hyaluronate. Replacement of aqueous humor by BSS 8 ml can decrease the residue of sodium hyaluronate to trace amount and the postoperative intraocular pressure can maintain in normal range.

Aqueous Humor↗
PubMed1998

Development, progression, and androgen-dependence of prostate tumors in probasin-large T antigen transgenic mice: a model for prostate cancer.

Probasin (PB) gene product is prostate-specific, epithelial cell in origin, and androgen-regulated. A large 12-kb promoter fragment of the PB gene (LPB) was linked to the simian virus 40 (SV40) large T antigen (Tag) deletion mutant (that removes the expression of the small t antigen) to deliver consistently high levels of transgene expression to the transgenic mouse prostate. Seven male founders, their male offspring, and all the male offspring from two female founders developed at least prostatic epithelial cell hyperplasia by 10 weeks of age, indicating that the incidence of transformation was 100%. Tumorigenesis in the LPB-Tag animals progressed in a manner similar to that observed in the human prostate. Initially, multifocal proliferating lesions were detected in the prostatic epithelium, which continued to progress into hyperplasia involving the entire epithelium and then low-grade dysplasia. Reactive stromal proliferation was induced and continued to develop throughout the progression to high-grade dysplasia, carcinoma in situ, and adenocarcinoma. Immunohistochemical studies indicated that most stromal cells stained positively for both androgen receptor and smooth muscle alpha-actin, suggesting that stromal overgrowth largely represented mesenchymal cells that had differentiated into smooth muscle cells. Epithelial cell transformation was accompanied by the down-regulation of differentiated function, as suggested by the loss of dorsolateral prostate-specific secretory proteins. Tumor growth was regarded as androgen-dependent because tumors regressed in animals castrated at 11 weeks of age, and androgen treatment restored both epithelial/stromal cell ratio and tumor growth. Furthermore, small populations of prostatic epithelial cells in castrated animals continued to proliferate, suggesting the potential for androgen-independent growth. Although prostatic metastasis to other organs was not observed, local invasion was detected. In summary, the LPB-Tag animal model is unique in that it is the only model generated with the Tag alone, thereby eliminating any influences of the small t antigen on prostate tumor formation. Moreover, this model undergoes molecular changes similar to those found in human prostate including: (a) the multi-focal nature of tumorigenesis, (b) the progressive histopathologic changes from low- to high-grade dysplasia similar to human prostatic intraepithelial neoplasia, (c) stimulation of reactive stromal proliferation, and (d) the androgen-dependent growth of the primary tumor. Thus, the LPB-Tag prostate tumor model will be useful for studying the sequential mechanisms underlying the development of multistep tumorigenesis.

Androgen-Binding Protein↗
PubMed1998

Transmission and natural regulation of infection with Ascaris lumbricoides in a rural community in China.

A longitudinal study on a cohort of 215 people who remained untreated from June 1993 to June 1994 was carried out using fecal egg counts to examine the course of transmission and aspects of the natural regulation of the infection with Ascaris lumbricoides. The results indicate that the parasite population remained relatively stable during the years since overall prevalence remained steady above 60%. About 40% of the people in the cohort retained their infection intensity status throughout the year, in terms of light, medium, and heavy infections. The regulation of infection in the population could be attributed to the tendency for the loss of worms from people with initial light infections and the movement to medium infection intensity status of people with both light and heavy infections. Compared with adults, children showed a stronger tendency of retaining initial medium infections but weaker tendencies for keeping initial light infections and clearing themselves of infection. Predisposition to light and medium infections was detected in people who had experienced an uninfected period of 4-12 mo before reinfection was established.

Adolescent↗
PubMed1998

Development, progression, and androgen-dependence of prostate tumors in probasin-large T antigen transgenic mice: a model for prostate cancer.

Probasin (PB) gene product is prostate-specific, epithelial cell in origin, and androgen-regulated. A large 12-kb promoter fragment of the PB gene (LPB) was linked to the simian virus 40 (SV40) large T antigen (Tag) deletion mutant (that removes the expression of the small t antigen) to deliver consistently high levels of transgene expression to the transgenic mouse prostate. Seven male founders, their male offspring, and all the male offspring from two female founders developed at least prostatic epithelial cell hyperplasia by 10 weeks of age, indicating that the incidence of transformation was 100%. Tumorigenesis in the LPB-Tag animals progressed in a manner similar to that observed in the human prostate. Initially, multifocal proliferating lesions were detected in the prostatic epithelium, which continued to progress into hyperplasia involving the entire epithelium and then low-grade dysplasia. Reactive stromal proliferation was induced and continued to develop throughout the progression to high-grade dysplasia, carcinoma in situ, and adenocarcinoma. Immunohistochemical studies indicated that most stromal cells stained positively for both androgen receptor and smooth muscle alpha-actin, suggesting that stromal overgrowth largely represented mesenchymal cells that had differentiated into smooth muscle cells. Epithelial cell transformation was accompanied by the down-regulation of differentiated function, as suggested by the loss of dorsolateral prostate-specific secretory proteins. Tumor growth was regarded as androgen-dependent because tumors regressed in animals castrated at 11 weeks of age, and androgen treatment restored both epithelial/stromal cell ratio and tumor growth. Furthermore, small populations of prostatic epithelial cells in castrated animals continued to proliferate, suggesting the potential for androgen-independent growth. Although prostatic metastasis to other organs was not observed, local invasion was detected. In summary, the LPB-Tag animal model is unique in that it is the only model generated with the Tag alone, thereby eliminating any influences of the small t antigen on prostate tumor formation. Moreover, this model undergoes molecular changes similar to those found in human prostate including: (a) the multi-focal nature of tumorigenesis, (b) the progressive histopathologic changes from low- to high-grade dysplasia similar to human prostatic intraepithelial neoplasia, (c) stimulation of reactive stromal proliferation, and (d) the androgen-dependent growth of the primary tumor. Thus, the LPB-Tag prostate tumor model will be useful for studying the sequential mechanisms underlying the development of multistep tumorigenesis.

Androgen-Binding Protein↗