Biomedical subjects

Jing Chen

Publications and source records attributed to Jing Chen.

At least 307 records · Page 17Linked to original sources

PubMed2003

Expression of hMSH2 gene and mutant p53 in sporadic digestive tract tumors.

OBJECTIVE: To investigate the role of mutated mismatch repair gene hMSH2 and mutant p53 gene in the carcinogenesis and development of sporadic digestive tract tumors. METHODS: hMSH2 gene in normal and tumor tissue of 30 digestive tract tumor specimens was examined using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) silver staining. The PCR product with an abnormal strand was sequenced directly. Mutant p53 protein in the tumor tissue was analyzed immunohistochemically. RESULTS: Six patients were identified as having mutated strands, three on hMSH2 exon 1 and three on hMSH2 exon 5. DNA sequencing revealed that all 6 patients had mutated basic groups that led to decrease in function of the hMSH2 protein. Forty percent (12/30) of patients were p53 positive. The frequency of mutated hMSH2 in p53 positive patients (41.7%) was significantly higher than in p53 negative patients (5.6%, P < 0.05). CONCLUSION: The mutation of hMSH2 plays an important role in the carcinogenesis and development of digestive tract tumors through stimulating p53 mutation.

DNA-Binding Proteins↗

PubMed2003

[Significance of TPMT activity and TGNs level detection for individualizing 6-mercaptopurine chemotherapy].

OBJECTIVE: To evaluate the activity and genotype of thiopurine methyltransferase (TPMT) and the concentration of thioguanine nucleotides (TGNs) as parameters for individualizing mercaptopurine (6-MP) therapy. METHODS: Erythrocyte TPMT activity was measured by means of radiochemical assay. Sequence specific primer (SSP) PCR and restriction fragment length polymorphism (RFLP) were used to determine the mutations in TPMT genomic DNAs. Erythrocyte TGNs concentration in acute lymphoblastic leukemia (ALL) patients after 6-MP treatment was detected by high-performance liquid chromatography (HPLC). RESULTS: The erythrocyte TPMT activity in Han population was 16.6 +/- 4.5U/ml pRBCs (man 16.8 +/- 5.0 U/ml pRBCs, woman 16.5 +/- 4.4 U/ml pRBCs), the activity in 8.1% of the samples was lower than 10 U/ml pRBCs. There was no difference for TPMT activity by gender, age, and between healthy donors and ALL patients. For TPMT genotypes, there were 5 cases of TPMT * 2, 4 TPMT * 3A, 6 TPMT * 3B, 10 TPMT * 3C and 5 unknown in 30 subjects who had low TPMT activity. In children with ALL, the TGNs level did show a negative correlation with TPMT activity at diagnosis and 7 approximately 14 days after 6-MP therapy and with WBC count 14 days after the determination of TGNs. CONCLUSION: Detection of TPMT activity before 6-MP therapy and TGNs level during 6-MP therapy may be helpful for preventing side effects from antipurine metabolic drug overdose, and individualizing 6-MP chemotherapy in children with ALL.

Adolescent↗

PubMed2003

A 3D model of SARS_CoV 3CL proteinase and its inhibitors design by virtual screening.

AIM: To constructed a three-dimensional (3D) model for the 3C like (3CL) proteinase of SARS coronavirus (SARS-CoV), and to design inhibitors of the 3CL proteinase based on the 3D model. METHODS: Bioinformatics analyses were performed to search the homologous proteins of the SARS-CoV 3CL proteinase from the GenBank and PDB database. A 3D model of the proteinase was constructed by using homology modeling technique. Targeting to the 3D model and its X-ray crystal structure of the main proteinase (Mpro) of transmissible gastroenteritis virus (TGEV), virtual screening was performed employing molecular docking method to identify possible 3CL proteinase inhibitors from small molecular databases. RESULTS: Sequence alignment indicated that the SARS-CoV 3CL proteinase was extremely homologous to TGEV Mpro, especially the substrate-binding pocket (active site). Accordingly, a 3D model for the SARS-CoV 3CL proteinase was constructed based on the crystal structure of TGEV Mpro. The 3D model adopts a similar fold of the TGEV Mpro, its structure and binding pocket feature are almost as same as that of TGEV Mpro. The tested virtual screening indicated that 73 available proteinase inhibitors in the MDDR database might dock into both the binding pockets of the TGEV Mpro and the SARS-CoV 3CL proteinase. CONCLUSIONS: Either the 3D model of the SARS-CoV 3CL proteinase or the X-ray crystal structure of the TGEV Mpro may be used as a starting point for design anti-SARS drugs. Screening the known proteinase inhibitors may be an appreciated shortcut to discover anti-SARS drugs.

Computational Biology↗

PubMed2003

Small envelope protein E of SARS: cloning, expression, purification, CD determination, and bioinformatics analysis.

AIM: To obtain the pure sample of SARS small envelope E protein (SARS E protein), study its properties and analyze its possible functions. METHODS: The plasmid of SARS E protein was constructed by the polymerase chain reaction (PCR), and the protein was expressed in the E coli strain. The secondary structure feature of the protein was determined by circular dichroism (CD) technique. The possible functions of this protein were annotated by bioinformatics methods, and its possible three-dimensional model was constructed by molecular modeling. RESULTS: The pure sample of SARS E protein was obtained. The secondary structure feature derived from CD determination is similar to that from the secondary structure prediction. Bioinformatics analysis indicated that the key residues of SARS E protein were much conserved compared to the E proteins of other coronaviruses. In particular, the primary amino acid sequence of SARS E protein is much more similar to that of murine hepatitis virus (MHV) and other mammal coronaviruses. The transmembrane (TM) segment of the SARS E protein is relatively more conserved in the whole protein than other regions. CONCLUSION: The success of expressing the SARS E protein is a good starting point for investigating the structure and functions of this protein and SARS coronavirus itself as well. The SARS E protein may fold in water solution in a similar way as it in membrane-water mixed environment. It is possible that beta-sheet I of the SARS E protein interacts with the membrane surface via hydrogen bonding, this beta-sheet may uncoil to a random structure in water solution.

Circular Dichroism↗

PubMed2003

[Detection of minimal residual disease in childhood B-ALL by flow cytometry].

OBJECTIVE: To establish a flow cytometric method for detecting minimal residual disease (MRD) in children with B-ALL and evaluate its clinical application. METHODS: Fifty-eight childhood B-ALL cases entered this study and 30 MRD analyses were performed after remission induction therapy. Four-color fluorochrome labeled monoclonal antibodies were used to analyze the cell immunophenotypes. Cells from normal bone marrow were used as controls. The leukemic cell populations located in flow cytometry dot plots different from those of normal were considered to be the markers of interest in the first step screening, and then used to monitor MRD step after therapy. RESULTS: Fifty-eight cases of childhood B-ALL were screened for antibodies combinations of interest and were identified in 89.7% (52/58) of these cases. The four-color antibody combinations consisted of CD(10)/CD(34)/CD(19) plus another effective marker such as CD(38), CD(65), CD(66c), CD(21). The sensitivity of this method was 0.01%, much higher than microscopic inspection. In 8 cases whose bone marrow microscopically showed no residual leukemic cells, the percentage of leukemic cells were identified with this method of 0.028%, 1.430%, 3.050%, 0.015%, 5.660%, 2.700%, 0.027%, and 0.069%, respectively. CONCLUSION: The application of flow cytometry in MRD monitoring can significantly improve the detection sensitivity in childhood B-ALL, thus facilitate the further treatment decision and follow-up.

Burkitt Lymphoma↗

PubMed2003

Using Tc-99m MIBI scintimammography to differentiate nodular lesions in breast and detect axillary lymph node metastases from breast cancer.

OBJECTIVE: To test the clinical value of using Tc-99m MIBI scintimammography (Tc-99m MIBI SMM) to differentiate nodular lesions in breasts and detect axillary lymph node metastases of breast cancer. METHODS: The subjects consisted of sixty female patients exhibiting unilateral palpable breast mass. The early and delay static acquisitions were undertaken in all subjects at 10 and 90 min after injection with Tc-99m MIBI. The acquisition included three positions: anterior supine, left lateral prone and right lateral prone. A special device for SMM which was developed by our laboratory was used. The ratio of [(T-B)/(NT-B)] was calculated as radioactivity of mass to that of opposite corresponding tissue, and [(T-B)/(NT-B)] > or = 1.21 was used as the cut-off for semi-quantitative discrimination of malignancy from benignity in semi-quantitative analysis. The final diagnosis was obtained from histology examination in all subjects. RESULTS: Using Tc-99m MIBI SMM to differentiate between nodular lesions in breasts, the diagnostic sensitivity and specificity were 92.9% and 90.6% respectively, the positive predictive value 89.7%, the negative predictive value 93.5%, and the accuracy 91.7%. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy obtained with Tc-99m MIBI SMM for detecting axillary lymph node metastases were 83.3%, 86.1%, 80%, 88.6% and 85% respectively. CONCLUSIONS: It is suggested that Tc-99m MIBI SMM may be not only valuable in differentiating malignant lesions from benign nodular masses of breast, but also helpful in detecting axillary lymph node metastases of breast cancer.

Adolescent↗

PubMed2003

[Characterization of CD10 expression and its significance in minimal residual disease detection in childhood B-acute lymphoblastic leukemia].

To observe the expressions of CD10 in childhood B-acute lymphoblastic leukemia (B-ALL) and to define the role of CD10 in minimal residual disease (MRD) detection. 58 cases of childhood B-ALL were studied in this program. Four-color flow cytometry was used to analyze the characteristics of B-ALL phenotypes. The four-color fluorochrome labeled antibody combinations of CD10 with other markers were used to detect MRD. The results showed that CD10 overexpression (CD10(bright)) was detected in 65.5% (38/58) of B-ALL patients and a strong correlation between CD10(bright) and CD34 expression was also observed, i.e. CD10(bright) expression most frequently happened in B-ALL with high percentage of CD34 positive cells. In detection of MRD, CD10(bright), combined with other markers, could effectively distinguish normal cells with leukemic cells, even if there was no any other marker that can be used. It is concluded that CD10(bright) expression correlates with high expression of CD34 in B-ALL, it is a good marker for MRD detection. The combination of CD10 and other markers can be applied in B-ALL MRD detection with flow cytometry.

Adolescent↗

PubMed2003

[Correlation of E-cadherin, beta-catenin and gamma-catenin gene expression with the invasion and metastasis of gastric carcinoma].

OBJECTIVE: To study the association of the expressions of E-cadherin, beta;- and gamma-catenins in gastric carcinoma tissues with the invasion and metastasis of the tumor. METHODS: From 60 patients with gastric carcinoma, the paraffin-embedded specimens including 60 carcinoma tissues, 20 precancerous lesions (10 intestinal metaplasia and 10 dysplasia specimens) and 20 corresponding normal tissues adjacent to the carcinomas were obtained for detecting E-cadherin, beta;- and gamma-catenin expressions by immunohistochemistry. RESULTS: Positive staining for E-cadherin, beta- and gamma-catenins was clearly observed on the cellular membrane throughout the epithelium in all the normal and metaplastic gastric mucosa. In 1 out of the 10 specimens of dysplastic mucosa, the staining for E-cadherin and beta;-catenin was absent but gamma-catenin staining appeared normal. Up to 80% (48/60) of the gastric carcinoma specimens presented abnormal staining for at least one of the components of the cadherin- catenin complex, showing a close correlation to Ming's classification, TNM staging and lymph node metastasis (P<0.05). The rates of abnormal expression were 6.67% for E-cadherin, 55% for beta;-catenin and 58.33% for gamma-catenin. CONCLUSIONS: Abnormal expression of E-cadherin, beta;- and gamma-catenins results in loss of epithelial cell-to-cell adhesion, with leads to uncontrolled cell growth, and may therefore participate in malignant transformation of the cells, and closely associates with the invasive growth and metastasis of human gastric carcinoma.

Cadherins↗

PubMed2003

[Clinical evaluation of 18F-FDE PET-CT in detecting malignant liver tumors].

OBJECTIVE: To evaluate the clinical value of (18)F-fluorodeoxyglucose ((18)F-FDG) positron-emission tomography (PET) combined with computer tomography (PET-CT) in the diagnosis and clinical staging of liver cancer. METHODS: (18)F-FDG PET-CT was performed preoperatively in 16 cases of primary and 8 metastatic liver cancers. The imaging features of the primary foci were analyzed, followed by measurement of standardized (18)F-FDG uptake. For the metastatic foci, the abnormal metabolism of (18)F-FDG was observed and CT, PET and PET-CT fusion images were obtained for accurate localization of these foci. RESULTS: (18)F-FDG uptake occurred in the supraclavicular region in 6 (37.5%) of the 16 patients with primary liver cancer, but was detected in the 8 patients with metastatic liver cancer. Fourteen metastatic nodules were found in 5 of the 16 patients with primary liver cancer, located in the lungs (2 cases) or the abdominal cavity (3 cases). CONCLUSIONS: Negative results of (18)F-FDG PET-CT imaging should be carefully evaluated for diagnosing primary liver cancers, considering the very low sensitivity (37.5%) of this imaging modality in this study. But in the cases of metastatic liver cancers this imaging modality may exhibit high sensitivity, and can also be of great value in clinical staging of the primary liver cancers.

Adult↗

PubMed2003

[Low dose methotrexate combined with GM-CSF induced differentiation of U937 cells].

OBJECTIVE: To explore the effect of methotrexate on acute monoblastic leukemia cells, and the potential role of low-dose methotrexate in the treatment of monoblastic leukemia. METHODS: By using U937 cell line as a model, the induced differentiation of MTX or GM-CSF or their combination was detected by NBT reduction test, morphological observation and CD(14) expression. TRAP-ELISA was used for measuring telomerase activity. RESULTS: After incubation with 20 nmol/L methotrexate for 24, 48, 72 and 96 hours, the size of the U937 cells increased, the nuclear/plasma ratio gradually decreased, NBT reductive test became positive, and CD(14) positive cells increased from 3% to 20% after 72 hours incubation, indicating partial differentiation. Treatment of U937 cells with 100 U/ml GM-CSF alone failed to induce differentiation. However, GM-CSF combined with low-dose methotrexate resulted in 63% of differentiated cells after 72 hours incubation, and telomerase activity of the U937 cells decreased from 2.11 (before treatment) to 1.48, 0.77, 0.24 (after treatment for 24, 48, 72 hrs respectively). The extent of the decrease of telomerase activity was in proportion with the degree of differentiation. CONCLUSION: Monoblastic leukemia might be treated with low-dose methotrexate plus GM-CSF as a differentiation induction regimen.

Cell Differentiation↗

PubMed2003

[Application of CD34+ autologous peripheral progenitor cell transplant in the treatment of children with refractory SLE].

OBJECTIVE: Systematic lupus erythematosis (SLE) is a severe disease which affects the patient for many years and there is no radical cure for the disease. To explore a possible way to treat children with refractory SLE, the authors treated 2 children with grade III and IV lupus nephropathy for 5 years and 7 years respectively, mainly presented with persistent thrombocytopenia, proteinuria, pleural effusion with CD34(+) autologous peripheral progenitor cells transplantation. METHODS: Mobilized with G-CSF and collected with CS-3000 Cell Separator, passed through the CliniMacs CD34(+) cell selection device, the count of CD34(+) cells obtained reached 1.0 x 10(6)/kg and 1.7 x 10(6)/kg, respectively with the remaining of 2.0 x 10(5)/kg and 1.0 x 10(4)/kg of CD3(+) cells individually. The selected CD34(+) cells were frozen at -80 degrees C. The conditioning regimen consisted of cyclophosphamide [50 mg/(kg x day) for 4 days] plus ATG [Fresennius S 5 mg/(kg x day) for 3 days]. After 48 h treatment with cyclophosphamide, the frozen stem cells were infused back to the patients. RESULTS: Neutrophils recovered on 9 and 7 days after transplantation respectively in these 2 cases. Beginning from 15 days, the platelet count recovered and remained at over 100 x 10(9)/L. The sign of Cushing's syndrome disappeared completely 3 months after transplantation because discontinuing the steroid. One child's height had a 5 cm increase within 6 months after stopping steroid and this was the first height gain during the 7 years since she had had the disease. Till this paper was written, these 2 children were followed up for 13 months and 6 months, respectively, all the original symptoms and autoantibodies related to autoimmune disorders disappeared. But the cell-mediated immunity did not recover yet with the CD4(+) cell level still remained at a lower level. CONCLUSION: The effect of CD34(+) autologous peripheral progenitor cell transplantation on the children with refractory SLE was satisfactory so far, but the long-term effect remains to be confirmed by further studies on more cases.

Adolescent↗

PubMed2003

[Results of Wilms' tumor trial (WT-99) in Shanghai children's medical center].

OBJECTIVE: Wilms' Tumor Trial (WT-99) of Shanghai Children's Medical Center was designed and conducted by applying therapeutic regimens stratified by stage and histology in accordance with National Wilms' Tumor Study (NWTS) criteria of U.S.A. The main aim of WT-99 was to reduce treatment of low-stage, favorable-histology (FH) tumors without impairing survival and to improve prognosis of stage III and IV (FH) and unfavorable-histology (UFH) tremors with more intensive chemotherapy. METHODS: Diagnosis and treatment was decided by the multi-disciplinary team including oncologists, surgeons, pathologists, radiologists and diagnostic radiologists. Twenty consecutively diagnosed patients were recruited between October 1998 and October 2002. The regimen for patients at favorable-histology (FH) stage I and II and anaplastic stage I was vincristine (Vcr) and dactinomycin (Act-D) only, while for those at focal anaplastic stage II to IV and FH stage III and IV the regimen was Vcr, Act-D and adriamycin (Adr). Patients at diffuse anaplastic stage II to IV and clear cell stage I to IV received four-drug regimen including Vcr, etoposide (VP16), Adr and cytoxan (CTX). For those at rhabdoid stage I to IV the regimen was carboplatin, VP-16 and CTX. Un-resectable patients received 2 courses of Ifosfamide, Vcr and VP-16 as pre-surgery therapy. No radiation therapy was used for patients at stage I and FH stage II. RESULTS: Twenty patients, from 7 months to 12 years old, were enrolled. Pathologic analysis showed fourteen cases were at their FH, three at unfavorable-histology (UFH), two at clear cell and one at rhabdoid stage. Five patients were at stage I, five at stage II, six at stage III, three at stage IV and one at stage V. Eighteen reached complete response (90%), and two failed. One relapsed after 24 months of CCR and reached the second CR after intensive chemotherapy. No therapy-related death happened. Survival rate (SR) was 90% (18/20) and event-free survival (EFS) was 85% (17/20) at 11-45 months, average 27 months. CONCLUSION: Multi-disciplinary team work model and protocol WT-99 are safe and effective for Wilms' tumor.

Academic Medical Centers↗

PubMed2002

Regulation of corticotropin-releasing hormone type 2 receptors by multiple promoters and alternative splicing: identification of multiple splice variants.

We demonstrate that multiple promoters and alternate splicing regulate expression of the human CRH receptor type 2 (CRHR2) gene. We show that flanking regions to the first exons drive promoter activity in both endogenously and nonendogenously expressing cell lines. Putative promoter elements have been identified that are conserved between species, including the comparison of CRHR2gamma in nonhuman primates that was previously known only in humans, which may be responsible for subtype tissue specific regulation. We have identified novel transcripts produced by alternate splicing of the first exon of CRHR2beta (beta1a) with various combinations of the 5' exons including a novel exon (beta1c) spliced to the common exons. The 5' structure of the gene permits many other combinations of alternate splicing that may arise as part of a regulatory mechanism controlling functional receptor expression. The 5'-untranslated region of the first exons has been extended; and 3' acceptor sites identified within the 5' untranslated region of CRHR2gamma and CRHR2alpha are used during alternate splicing of CRHR2beta upstream exons. This has important implications because various reports on the expression of CRHR2gamma and CRHR2alpha have been unable to discriminate between the functional receptor and CRHR2beta alternate splice variants. Only the described sequences upstream of the 3' splice site are unique to CRHR2gamma and CRHR2alpha.

5' Untranslated Regions↗

PubMed2002

Regulation of transcription of the murine gamma-glutamyl hydrolase gene. Delineation of core promoter A and the role of LYF-1, E2F and ETS-1 in determining tumor-specific expression.

Our earlier studies (Gene 268 (2001) 183) showed that transcription of the mouse gamma-glutamyl hydrolase (gamma GH) gene is under the control of two separate promoters widely distributed within the genome. We now report on further studies examining the functional characteristics of the more efficient promoter (promoter A) which is contiguous with an exon 1 (exon A1a) alternate within the main body of the gene. Functional deletion analysis of promoter A in pGL3 transfected in NIH3T3 cells defined a 189 bp region of sequence 26 bp upstream of exon A1a as mediating core promoter transcriptional activity. Further functional deletion analysis and site-directed mutagenesis attributed the activity of this core region to the presence of five SP1 sites within the most upstream 130 bp of sequence and the presence of three cis-active elements, Ets-1, Lyf-1 and E2F in the remaining downstream 59 bp of sequence. Electrophoretic gel-mobility shift assays showed that differences in the binding of trans-acting factors to these three elements accounts for the tumor-specific expression of this gene. Finally, analysis by fluorescent in situ hybridization revealed that promoter A and the main body of the mouse gamma GH gene are located between A3 and A5 on chromosome 4. This is an interesting finding in light of our earlier results which located promoter B and two associated alternates of exon 1 of this gene on chromosome 17.

3T3 Cells↗

PubMed2002

Factors associated with hypertension control in the general population of the United States.

BACKGROUND: Uncontrolled hypertension is the most common and important risk factor for cardiovascular and renal disease. We studied factors associated with hypertension control in the Third National Health and Nutrition Examination Survey. METHODS: A total of 3077 non-Hispanic whites, 1742 non-Hispanic blacks, and 1067 Mexican Americans 18 years or older with hypertension were included in the current analysis. Blood pressure was measured by trained observers by means of a standard mercury sphygmomanometer, and controlled hypertension was defined as a mean systolic/diastolic blood pressure less than 140/90 mm Hg. RESULTS: Percentages of persons with controlled hypertension differed significantly by ethnicity and sex: 19.2% and 28.7% for white men and women, 17.5% and 28.6% for black men and women, and 12.7% and 18.0% for Mexican American men and women, respectively. After adjustment for important covariables, percentages of persons with controlled hypertension were significantly higher among persons who were currently (odds ratio [OR] 2.39; 95% confidence interval [CI], 1.52-3.74) or formerly (OR, 1.81; 95% CI, 1.12-2.93) married, had private health insurance (OR, 1.59; 95% CI, 1.02-2.49), visited the same facility for their health care (OR, 2.77; 95% CI, 1.88-4.09) or saw the same provider for their health care (OR, 2.29; 95% CI, 1.74-3.02), had their blood pressure checked during the preceding 6 months (OR, 8.00; 95% CI, 3.75-17.1) or 6 to 11 months (OR, 5.31; 2.51-11.2), and reported using lifestyle modification to control their hypertension (OR, 6.02; 95% CI, 4.20-8.63). CONCLUSION: These data strongly suggest that access to a regular source of health care and modification of lifestyle are important factors in the control of hypertension in the community.

Behavior Therapy↗

PubMed2002

A Myb dependent pathway maintains Friend murine erythroleukemia cells in an immature and proliferating state.

Friend murine erythroleukemia (MEL) cells are transformed erythroid precursors that are held in an immature and proliferating state but can be induced to differentiate in vivo by treatment with a variety of chemical agents such as N, N-hexamethylene bisacetamide (HMBA). To investigate the role of Myb proteins in maintaining MEL cells in an immature and proliferating state we have produced stable transfectants in the C19 MEL cell line that contain a dominant interfering Myb allele (MEnT) under the control of an inducible mouse metallothionein I promoter. When expression of MEnT protein was induced with ZnCl2, the stable transfectants differentiated with kinetics that were similar to wild type C19 MEL cells treated with HMBA, including induction of alpha-globin mRNA expression, assembly of hemoglobin and growth arrest. Expression of endogenous c-myb and c-myc was also decreased in response to MEnT. Expression of mad-1 mRNA was rapidly increased in response to expression of MEnT resulting in a shift from predominantly c-Myc/Max complexes to predominantly Mad/Max containing complexes. These results strongly suggest that C19 MEL cells are held in an immature and proliferating state by a pathway that is dependent on Myb activity.

Acetamides↗

PubMed2002

[The effects of endothelin blockade on renal expression of angiotensin II type 1 receptor in diabetic hypertensive rats].

OBJECTIVE: To investigate the changes of angiotensin II type 1 (AT1) receptor in the kidney of spontaneously hypertensive rats (SHR) with diabetes and the influence of endothelin receptor antagonist bosentan. METHODS: Streptozotocin-induced diabetic SHR were divided into four groups: groups treated by cilazapril, bosentan + amlodipine, and amlodipine rsspectively, and untreated group, 6 rats in each group. Six SHR rats and six WKY rats were used as hypertensive and normotensive controls respectively. By the end of the 4th week, all rats were anasthetized and catheteization was conducted to their right common carotis arteries to measure the mean arterial blood pressure and collect blood samples to determine the blood sugar and creatinine by biochemical analyzer, and plasma angiotensin II level by radioimmunoassay. Then the rats were killed and their kidneys were taken. The renal angiotensin II (Ang II) receptor and expression of AT1 receptor was determined by RT-PCR and Western blotting. One day before the rats were killed, 24-hour urine was collected to determine the urinary protein and creatinine. RESULTS: In untreated diabetic SHR, enhanced blood pressure and urinary protein excretion, reduced creatinine clearance, as well as significantly increased plasma and renal Ang II levels were observed compared with those in WKY rats. Immunohistochemistry, Western blotting and semi-quantitatively RT-PCR methods showed that the protein and mRNA levels of AT1 receptor in kidney were significantly reduced in untreated diabetic SHR compared to those in WKY rats. All these abnormalities were attenuated by bosentan + amlodipine and cilazapril therapies. CONCLUSION: Bosentan prevents the down-regulation of AT1 receptor in the kidneys of diabetic hypertensive rats.

Amlodipine↗

PubMed2002

A carbonyl oxygen migration in electrospray ionization mass spectrometry and its application in differentiating alpha- and beta-alanyl peptides.

A novel rearrangement reaction with a carbonyl oxygen migration was observed in the electrospray ionization tandem mass spectra of N-diisopropyloxyphosphoryl dipeptides and their analogues. A possible mechanism was proposed and supported by the MS/MS study, derivatization of different functional groups and deuterium labeling experiments. It was found that metal ions could catalyze the rearrangement through a five-membered ring intermediate. A strong affinity between the phosphoryl group and oxygen atom in the gas phase was proposed to result in this kind of rearrangement reaction, which might provide some basic information on the nature of phosphorylation in biochemistry. The replacement of N-terminal alpha-alanine by beta-alanine stopped the migration, which provides a simple method for differentiating the alpha- and beta-alanine residues at the N-terminus of peptides.

Alanine↗