Biomedical subjects

S Yu

Publications and source records attributed to S Yu.

At least 73 records · Page 4Linked to original sources

PubMed2001

Protein kinase CK2 signal in neoplasia.

Protein kinase CK2 (previously known as casein kinase II) is a protein serine/threonine kinase that has been implicated in cell growth and proliferation. The focus of this review is on the apparent role of CK2 in cancer. Studies from several laboratories have shown a dysregulated expression of the kinase in tumors. Nuclear matrix and chromatin appear to be key sites for signaling of the CK2 activity in relation to cell growth. Several types of growth stimuli produce a common downstream response in CK2 by enhancing its nuclear shuttling. The neoplastic change is also associated with changes in intracellular localization of the kinase so that a higher nuclear localization is observed in tumor cells compared with normal cells. Experimental studies suggest that dysregulated expression of the alpha subunit of CK2 imparts an oncogenic potential in the cells such that in cooperation with certain oncogenes it produces a profound enhancement of the tumor phenotype. Recent studies have provided evidence that overexpression of CK2 in tumor cells is not simply a reflection of tumor cell proliferation alone but additionally may reflect the pathobiological characteristics of the tumor. Of considerable interest is the possibility that CK2 dysregulation in tumors may influence the apoptotic activity in those cells. Approaches to interfering with the CK2 signal may provide a useful means for inducing tumor cell death.

Adenocarcinoma↗

PubMed2001

Measurement of tumor blood flow using colored dye extraction microspheres in two rat tumor models.

A technique that can measure tumor blood flow easily, accurately and economically is required to study tumor angiogenesis and angiogenesis inhibition. Using dye extraction colored microspheres, we measured tumor blood flow in Sato lung carcinoma (SLC) and ascites hepatoma LY80 in rats. Colored microspheres were infused into tumor-bearing rats via a catheter in the left ventricle. After removal of the tumor and the liver, the tissue samples were dissolved, and the microspheres were isolated. Dye was extracted, and the dye concentration was quantified by spectrophotometry. The dye concentration per gram of tumor was compared with that per gram of liver as follows (AU = absorbency units): [AU per gram of tumor] / [AU per gram of liver] X 100 = (%). Tumor blood flow corrected for wet weight was calculated as follows: [blood flow to tumor] = [AU per gram of tumor] X [reference withdrawal rate] / [AU per gram of reference blood]. Tumor blood flow rate was divided by tumor weight to yield ml. min-1g-1. The tumors were also examined histologically, and casts of the tumor vasculature were prepared with silicone rubber. Blood flow 2 weeks after transplantation was equivalent to 1/10 and 1/2 at 1 week in SLC and LY80 tumors, respectively (SLC, P=0.009, n=10; LY80, P=0.05, n=10). These decreases in tumor blood flow were associated with underlying pathological and vascular change. Blood flow in LY80 tumors negatively correlated with tumor volume (P=0.009, n=10). We concluded that the colored microsphere method, initially developed to measure organ blood flow, is also useful for estimating tumor blood flow in rats.

Animals↗

PubMed2001

Regulation of hepatic cytochrome P450 2C11 via cAMP: implications for down-regulation in diabetes, fasting, and inflammation.

The effect of glucagon and its second messenger cAMP on cytochrome P450 2C11 (CYP2C11) expression was investigated in primary hepatocytes cultured on Matrigel. Glucagon, epinephrine, forskolin, and the cAMP derivatives dibutyryl cAMP, (S(p))-adenosine 3',5' cyclic monophosphothioate (S(p)-cAMPS), and 8-(4-chlorophenylthio)-cAMP, but not dideoxyforskolin, all down-regulated CYP2C11 mRNA expression to approximately 20% of control levels in a concentration-dependent manner. Using the transcriptional inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole, CYP2C11 mRNA was found to have a half-life of 9.8 h. The kinetics of suppression of CYP2C11 mRNA by glucagon and forskolin was similar to that obtained with the transcriptional inhibitor, suggesting that glucagon and forskolin act at the transcriptional level. CYP2C11 expression was more sensitive to suppression by glucagon at low insulin concentrations than at higher concentrations. (R(p))-Adenosine 3',5' cyclic monophosphothioate inhibited the down-regulation of CYP2C11 by S(p)-cAMPS, consistent with a competitive blockade of protein kinase A activation. These results suggest a role for glucagon in the down-regulation of CYP2C11 in diabetic rats, and provide a possible explanation for the known sensitivity of this cytochrome P450 to suppression in various stress and disease models.

Animals↗

PubMed2001

Infant mortality in Louisiana--identifying the risks.

The state of Louisiana consistently has one of the five highest infant mortality rates in the nation and the racial disparity within the state is glaring. The purpose of this paper is to analyze the state's linked birth and death infant data set for the birth cohort of 1990-1998, and to identify the "at risk" population. We have analyzed data from the 1990 to 1998 birth and infant death cohort in Louisiana to determine mothers' characteristics that are associated with infant death. These include extremely young and old ages, unmarried marital status, lower levels of education, and prenatal care. A mother's race is also associated with higher future mortality for her infant, with black mothers and their infants being at greater risk than white ones. Because the infant mortality rate is higher for black infants than for white ones, Louisiana's higher infant mortality rate can be seen as a result of the higher proportion of black births. Main concerns in reducing infant mortality rates include reducing incidence of low birth weights specifically among black births primarily by providing adequate prenatal care.

Adolescent↗

PubMed2001

Identification of a transcription factor, an 80-kDa protein that interacts with the HLH recognition motif of the rat p53 promoter.

The p53 promoter has been shown to contain a number of potential regulatory motifs. It was previously reported that the upstream stimulating factor (USF) played a central role in regulating the p53 expression. The USF binding site, E-box, is located around 40 bp upstream of the major transcription start site. In this study, it was confirmed that the E-box binds to proteins by DNase I footprinting assay. In the electrophoretic mobility shift assay (EMSA), two retarded bands were detected. One band was abolished by the competition of USF consensus oligonucleotide, but the other band was not. This result indicated that a factor, other than USF, was bound to the E-box. The molecular masses of the binding proteins were determined by a Southwestern-blotting assay. As a result, 46- and 80-kDa proteins were detected. The 46-kDa protein was eliminated by the competition of USF consensus oligonucleotide. Also, the Southwestern-blotting assay with 32P-labeled USF consensus oligonucleotide showed only a 46-kDa protein. Therefore, the 46-kDa protein was USF. These results showed that USF and the 80-kDa protein were bound to the E-box. In addition, it was proved by in vitro transcription assay that this 80-kDa protein had a basal transcriptional activity.

Animals↗

PubMed2001

[Hypoxic preconditioning enhances hypoxic tolerance of hippocampal neurons and synaptic function of rat].

Hypoxic preconditioning with different simulated altitudes (3,000 m and 5,000 m) was performed on Wistar rats and the evoked population spikes were recorded from the hippocampal slices of these rats. The results showed that the appearance of hypoxic injury potential (HIP) and the disappearance of presynaptic volley (PV) were significantly delayed in response to acute lethal hypoxia. HIP and PV delay became more apparent when the hypoxic preconditioning altitude was increased from 3,000 m to 5,000 m. After reoxygenation, the recovery rate of PV in hypoxic preconditioning groups at 3,000 m and 5,000 m was apparently higher than that of control. The above results suggest that hypoxic preconditioning of animals in vivo increases hypoxic tolerance of hippocampal neurons.

Animals↗

PubMed2001

[Study on the effects of DNA and natural killer cell damage induced by microcystins LR].

OBJECTIVE: Microcystin is a group of algae toxin which causes liver cancer. In this paper we tried to study the carcinogenic and tumor promotion mechanism of Microcystin LR (MCLR). METHODS: The single cell microgel electrophoresis assay (MGE) and 3H-TdR releasing assay were used to study the effects of on DNA damage and natural killer cell (NK cell) activity. RESULTS: The different doses of MCLR caused DNA damage in rat lymphocytes compared to 0.85% NaCl. However, no time-dependent relationship and dose dependent relationship between MCLR and DNA migration were observed, and the DNA damage was recovered rapidly after MCLR treatment. At the same time MCLR reduced NK cells activity in mice. CONCLUSION: The above results provide some evidence on the mechanisms of carcinogenicity and promotional effects of MCLR at cellular and molecular levels.

Animals↗

PubMed2001

[An experimental study of matrix metalloproteinase inhibitor BB-94 inhibits the invasion and metastasis of the human salivary adenoid cystic carcinoma in vitro and in vivo].

OBJECTIVE: To study the inhibitory effect of matrix metalloproteinase inhibitor BB-94 on the invasion and metastasis of salivary adenoid cystic carcinoma in vitro and in vivo. METHODS: Reconstituted basement membrane invasion assay was used to evaluate invasive ability of cancer cells. Type IV collagenase was assessed by PAGE substrate zymography. In addition, the antimetastasis effect of the compound was studied in in vivo experiments using nude mice model of pulmonary metastasis with ACC-M line of human salivary adenoid cystic carcinoma. RESULTS: BB-94, at the concentrations of 10 mumol/L and 100 mumol/L, suppressed the reconstituted basement invasion of ACC-M human salivary adenoid cystic carcinoma by 32.9%, 53.2% and reduced Type IV collagenase activities in the serum-free supernatant of the same cells. The pulmonary metastasis rate of the control and treated groups was 90.0% and 20.0%, respectively (P < 0.01). The lung weight of the control and treated groups was (0.2090 +/- 0.0667) g and (0.1532 +/- 0.0378) g, respectively (P < 0.05). CONCLUSIONS: These results suggest that the matrix metalloproteinase inhibitor BB-94 has a strong inhibitory effect on invasion and metastasis of salivary adenoid cystic carcinoma.

Animals↗

PubMed2001

[NIES-90 microcystin producing algae strain genome library construction and one isolated gene analysis].

OBJECTIVE: To construct a plasmid microcystis genome library for microcystin (MC) pertaining gene family screening or microcystis strain specific gene screening. METHODS: Extracting genome DNA from MC producing strain NIES-90, then digesting DNA by HindIII and ligating to CIPase treated pUC18/HindIII fragment which later transformed to JM109. After checking the library by Xgal/Antibiotics plate, clones isolation, a few clones were sequenced and specific primers synthesized; finally, PCR was used to testify clone's NIES-90 strain specificity. RESULTS: Successfully constructed a NIES-90 genome plasmid library with following functions: a) cloning efficiency more than 95% by comparing the white/blue clones ratio in Xgal Plate; b) 200-700 bp average insert length with 3 x 10(5) independent clones by independent clones analysis; c) 10 times more coverage of original NIES-90 genome; d) strong strain specificity by cross PCR analysis of some clone's sequence in two different microcystis strains compared with FACHB-469. CONCLUSION: We successfully constructed a NIES-90 MC producing microcystis strain's genome plasmid library which could be used for screening MC pertaining gene family because of high strain specificity of some clones.

DNA, Plant↗

PubMed2001

Nasal carriage of Streptococcus pneumoniae among children in Beijing.

OBJECTIVE: To investigate the antimicrobial susceptibility of Streptococcus pneumoniae carried in the nose among children in Beijing and the distribution of serotypes, and to analyze the risk factors for nasal carriage of penicillin non-susceptible S. pneumoniae. METHODS: A disk diffusion test was applied to detect the antimicrobial susceptibilities of S. pneumoniae to erythromycin, trimethoprim-sulfamethoxazole, chloramphenicol and tetracycline. The E test was applied to determine the minimal inhibitory concentrations of penicillin, cefuroxime, cefotaxime, augmentin and imipenem. S. pneumoniae isolates were serotyped by the Quellung reaction. RESULTS: S. pneumoniae that was resistant to penicillin or cefuroxime was not found, but S. pneumoniae intermediate resistant to penicillin and cefuroxime accounted for 8.2% and 2.1%, respectively. All of the isolates were susceptible to cefotaxime, augmentin and imipenem. S. pneumonia that was resistant to erythromycin, trimethoprim-sulfamethoxazole and tetracycline were extremely numerous, accounting for 72%, 70% and 79%, respectively. Five serotypes (19, 6, 14, 23, 17) accounted for 54.7%, and nontypables accounted for 20.6% of all the S. pneumoniae. Previous history of otitis media was a risk factor we found for nasal carriage of penicillin non-susceptible S. pneumoniae. CONCLUSIONS: Continued surveillance of the antimicrobial susceptibilities of S. pneumoniae is necessary. A larger scale investigation is needed to identify if the 7 or 9-valent conjugate pneumococcal vaccine is appropriate for Chinese children.

Child, Preschool↗

PubMed2001

[Influence of fertilization depth on root system senescence of upland wheat after anthesis].

A soil column study showed that fertilization in a depth of 20-40 cm sustained the activities of superoxide dismatase (SOD) and catalase (CAT) in root system at a high level, meanwhile the root system vigor, the soluble protein content in root system decreased slowly, and the content of malondiadehyde (MDA) in wheat root system decreased, which delayed its senescence. It is considered that the depth (20-40 cm) of fertilization could be used as an index for delaying senescence.

Catalase↗

PubMed2001

Comparison of CT virtual endoscopy with electronic colonoscopy in 30 colonic carcinoma patients.

OBJECTIVE: To evaluate the clinical application of CT virtual endoscopy (CTVE) in the diagnosis and treatment of colonic carcinoma. METHODS: We collected 30 patients pathologically proven to have colonic carcinomas as examined by CTVE and electronic colonoscopy (EC), correlating the CTVE and EC images respectively with surgical pathology in three aspects: tumor morphological features, degree of circumferential bowel wall involvement and longitudinal extent of tumor. RESULTS: CTVE imaging of colonic carcinomas showed morphological features: polypoid pattern (11 patients), ulcerative pattern (11), and infiltrative pattern (8); degree of circumferential bowel wall involvement: less than 1/2 (4 patients), from 1/2 to 3/4 (6), and more than 3/4 (20); and their longitudinal extent: 1.0-3.0 cm (7 patients), 31-5.0 cm (10), and 5.1-11.0 cm (13). Correlation of CTVE and EC with surgical pathology was found. Comparison of CTVE with surgical pathology showed tumor morphological features: concordant (26 patients), and disconcordant (4); degree of circumferential bowel wall involvement: concordant (25), disconcordant (5); and longitudinal extent of the tumor: concordant (23), disconcordant (7). Comparison of EC with surgical pathology showed tumor morphological features: concordant (22 patients), disconcordant (8); degree of circumferential bowel wall involvement: concordant (28), disconcordant (2); and longitudinal extent of the tumor: concordant (14), disconcordant (3), and undefined by EC (13). CONCLUSIONS: The images obtained by CTVE in colonic carcinoma are similar to those obtained by EC. CTVE is an excellent alternative to EC for patients who cannot tolerate EC and for cases with incomplete EC.

Adult↗

PubMed2001

The preparation of rat heme oxygenase-1 mutant to reduce the level of bilirubin.

OBJECTIVE: To prepare rat heme oxygenase-1 (HO-1) mutants and to determine the activity and inhibition of this mutated enzyme. METHODS: pcDNA3HO1 containing truncated native rat HO-1 cDNA and pcDNA3HO1 delta 25 carrying mutated rat HO-1 cDNA (His25Ala) were constructed, respectively. COS-1 cells transfected with pcDNA3HO1 and pcDNA3HO1 delta 25 were collected and their activities were analyzed. RESULTS: Native rat HO-1 was highly expressed in transfected cells and its activity was 13,688-15,600 U/mg protein per hour. However, the enzyme activity of mutated HO-1 declined and the value was 1948-2160 U/mg protein per hour. When an equal amount of mutant was added to the enzyme reaction system, the level of bilirubin decreased by 42%. CONCLUSION: The His25Ala mutant reduced the formation of bilirubin, suggesting that the mutant could completely bind the heme with native enzyme.

Animals↗

PubMed2001

[The relationship between cyanotoxin (microcystin, MC) in pond-ditch water and primary liver cancer in China].

OBJECTIVE: To explore the relationship between primary liver cancer (PLC) and MC in drinking pond-ditch water. METHODS: Epidemiological and ecological assays, Meta-analysis and risk assessment were used in this study. Cyanotoxin (Microcystin, MC) in the water of different sources was detected by ELISA. The F344 and HBVx transgenic mice were used to confirm the promotion effect on PLC and the synthetically carcinogenic effect of HBV, aflatoxin and MC. RESULTS: Using Meta-analysis the results of six case-control studies showed that the pooled odds ratio (OR) was 2.46 (95% CI 1.69-2.59), population attributable rick (PAR) was 30.39% (95% CI, 23.30%-37.47%), heterogeneity test P > 0.05. Eutrophication led to cyanobacterial bloom in the pond-ditch water. Cyanotoxin released from dead cyanobacteria was hepatotactic tumor promoter. In HBVx transgenic rats, hepatocellular carcinoma was induced by the joint administration of aflatoxin B1 and cyanotoxin. Epidemiological study showed that the recombined index of HBsAg, aflatoxin-albumin adducts and drinking of pond-ditch water correlated with PLC mortalities in 13 townships. CONCLUSION: Microcystin in the pond-ditch water is a hepatotactic toxin which can induce hepatitis and promote development of hepatocellular carcinoma. The combined effect of microcystin, HBV and aflatoxin may be responsible for the endemicity of PLC.

Aflatoxin B1↗

PubMed2001

[Postoperative follow-up of mural ameloblastoma].

OBJECTIVE: To investigate the determinant of recurrence in mural ameloblastoma. METHODS: Forty-four cases of mural ameloblastoma were followed up postoperatively for 1 year to 25 years and 4 months (mean of 5.7 years). RESULTS: 1. The recurrence is more likely to recur in curettage group (8/35) than in radical surgery group (1/9); 2. The recurrence is more in intramural (4/7) and complex (3/4) group more than in intracavity group (0/15) after curettage treatment; 3. Those with honeycomb appearance (3/3) recurred more than those with unilocular appearance (1/20); 4. It recurred mostly within 2 years postoperatively (7 recurrences in 5 cases); 5. Recurrent cases were susceptible to repeated recurrence after recurettage. CONCLUSIONS: 1. The lesion with honeycomb appearance should be treated with radical surgery; 2. The follow-up should be emphasized for those with intramural or complex feature; 3. The curettage cases should be followed routinely for 5 years postoperatively.

Ameloblastoma↗

PubMed2001

[The treatment of osteoporosis and bone resorption of alveoli with alendronate in rat model].

OBJECTIVE: To evaluate the anti-osteoporosis effect of alendronate on bone in rat model. METHODS: The osteoporosis and alveolar bone resorption animal model were established in rats. The experimental groups were given alendronate in 5 mg/kg BW by subcutaneous injection after first day of ovariectomy and dental ligature, three times a week for 6 weeks. All the animals were sacrifised 12 weeks after the operation. The blood samples were collected for determination of biochemical indices. The left femora and jaw bones were processed for histomorphometry. The right femora and mendibles were prepared for determination of bone density and bone biodynamics. RESULTS: As compared with the control groups(without alendronate), the values of experimental groups (with alendronate) were all significantly improved on bone density, bone anti-flexure ability and body weight. The alkaline phosphatase, calcium in serum of ovariectomy groups(without alendronate) were obviously increased. In the experimental group, however, these indices were close to normal levels. In histomorphometry, there were little inflammation in gingiva and no obvious bone resorption in the alveolar crests of the experimental groups; but there were obvious gingivitis and alveolar crests resorption of the control groups. CONCLUSIONS: Alendronate can effectively prevent bone loss to reduce osteoporosis in ovariectomized rats and prohibit pathological alveolar bone resorption.

Alendronate↗

PubMed2001

[Alteration of Fas/FasL gene expression in oral squamous cell carcinoma cell line Tca83 by retinoid acid].

OBJECTIVE: To study the induction of apoptosis by retinoid acid(RA) in Tca83 cell line and the expression of correlative Fas/FasL gene. METHODS: Apoptosis of Tca83 was detected by TUNEL, the expression of Fas/FasL-mRNA was detected by RT-PCR and cell immunohistochemical technique. RESULTS: The cell apoptosis number of Tca83 in RA group was significantly higher than that in non-RA groupe on day 5(P < 0.05). The expression of Fas-mRNA in RA group was also much higher than that in non-RA group on day 5(P < 0.05), but the level of FasLmRNR had no change. Immunohistochemistry also showed, after RA treatment, the Fas stain was enhanced. CONCLUSION: The result suggests that apoptosis induced by RA may be resulted from the enhancement of Fas gene transcription and translation.

Antineoplastic Agents↗

PubMed2001

Response of cancer cells to molecular interruption of the CK2 signal.

Protein kinase CK2 is one of the key cellular signals for cell survival, growth, and proliferation. It is has been observed to be elevated in various cancers that have been examined. Various observations suggest that moderate dysregulation of CK2 may profoundly influence the cell response. We have examined the effects of interfering with the CK2 signal in various cancer cell lines by employing antisense oligodeoxynucleotides (ODN) against the alpha and beta subunits of CK2. Our results demonstrate that antisense CK2-alpha and antisense CK2-beta ODNs markedly influence cell viability of these cancer cells in a dose and time-dependent manner. Antisense CK2-alpha was slightly more effective than antisense CK2-beta in most of the cells tested. The efficacy of the antisense ODN seemed to vary with the cell type; however, in all cases potent induction of apoptosis was observed. Significantly, the effects of the antisense ODN on the CK2 activity in the nuclear matrix were relatively small compared to the much stronger induction of apoptosis in cells. This suggests that modest downregulation of CK2 can evoke a much greater apoptotic response in cancer cells.

Apoptosis↗