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Biomedical subjects

N Shen

Publications and source records attributed to N Shen.

At least 19 recordsLinked to original sources

Rapamycin induces feedback activation of Akt signaling through an IGF-1R-dependent mechanism.

Rapamycin and several analogs, such as CCI-779 and RAD001, are currently undergoing clinical evaluation as anticancer agents. In this study, we show that inhibition of mammalian target of rapamycin (mTOR) signaling by rapamycin leads to an increase of Akt phosphorylation in Rh30 and RD human rhabdomyosarcoma cell lines and xenografts, and insulin-like growth factor (IGF)-II-treated C2C12 mouse myoblasts and IGF-II-overexpressing Chinese hamster ovary cells. RNA interference-mediated knockdown of S6K1 also results in an increase of Akt phosphorylation. These data suggest that mTOR/S6K1 inhibition either by rapamycin or small interfering RNA (siRNA) triggers a negative feedback loop, resulting in the activation of Akt signaling. We next sought to investigate the mechanism of this negative feedback regulation from mTOR to Akt. Suppression of insulin receptor substrate (IRS)-1 and tuberous sclerosis complex-1 by siRNAs failed to abrogate rapamycin-induced upregulation of Akt phosphorylation in both Rh30 and RD cells. However, pretreatment with h7C10 antibody directed against insulin-like growth factor-1 receptor (IGF-1R) led to a blockade of rapamycin-induced Akt activation. Combined mTOR and IGF-1R inhibition with rapamycin and h7C10 antibody, respectively, resulted in additive inhibition of cell growth and survival. These data suggest that rapamycin mediates Akt activation through an IGF-1R-dependent mechanism. Thus, combining an mTOR inhibitor and an IGF-1R antibody/inhibitor may be an appropriate strategy to enhance mTOR-targeted anticancer therapy.

Animals↗

Protein interaction for an interferon-inducible systemic lupus associated gene, IFIT1.

OBJECTIVE: To identify disease-related genes and immune-regulatory pathways in the pathogenesis of systemic lupus erythematosus (SLE) by using gene expression profiling and protein-protein interaction analysis. METHODS: Peripheral white blood cell gene expression profiles of 10 SLE patients were determined by oligonucleotide microarray analysis. Clustering of the gene expression profile was compared with the clinical immune phenotype. SLE-induced genes that were over- or under-expressed were determined and independently validated using a real-time polymerase chain reaction (PCR) method. To study their potential function and the possible pathways involved, a candidate gene was cloned and a GST (glutathione S-transferase) fusion protein was expressed in Escherichia coli. The fusion protein was further purified using the glutathione Sepharose 4B system, and was treated as bait to capture prey from SLE peripheral white blood cell lysate. MALDI-TOF (matrix-assisted laser desorption/ionization-time-of-flight) mass spectrometry was then performed to determine the prey protein. RESULTS: Similarity was found between the gene expression profile and the immune phenotype clusters of the SLE patients. More than 20 disease-associated genes were identified, some of which have not been related to SLE previously. Of these genes, a cluster of interferon-induced genes were highly correlated. IFIT1 (interferon-induced with tetratricopeptide repeats 1) was one of these genes, and overexpression of its mRNA was confirmed independently by real-time PCR in a larger population (40 SLE patients and 29 normal controls). An IFIT1 protein- protein interaction study showed that IFIT1 may interact with Rho/Rac guanine nucleotide exchange factor. CONCLUSION: The gene expression profile seems to be the molecular basis of the diverse immune phenotype of SLE. On the basis of the SLE-related genes found in this study, we suggest that the interferon-related immune pathway is important in the pathogenesis of SLE. IFIT1 is the first gene described as a candidate gene for SLE, and may function by activating Rho proteins through interaction with Rho/Rac guanine nucleotide exchange factor. IFIT1 and the interferon-related pathway may provide potential targets for novel interventions in the treatment of SLE.

Adaptor Proteins, Signal Transducing↗

Analysis of gene expression profiles in human systemic lupus erythematosus using oligonucleotide microarray.

Epidemiologic studies suggest a strong genetic component for susceptibility to systemic lupus erythematosus (SLE). To investigate the genetic mechanism of pathogenesis of SLE, we studied the difference in gene expression of peripheral blood cells between 10 SLE patients and 18 healthy controls using oligonucleotide microarray. When gene expression for patients was compared to the mean of normal controls, among the 3002 target genes, 61 genes were identified with greater than a two-fold change difference in expression level. Of these genes, 24 were upregulated and 37 downregulated in at least half of the patients. By the Welch's ANOVA/Welch's t-test, all these 61 genes were significantly different (P<0.05) between SLE patients and normal controls. Among these genes with differential expression, IFN-omega and Ly6E (TSA-1/Sca-2) may play an important role in the mechanism of SLE pathogenesis. TSA-1 antigens may represent an important alternative pathway for T-cell activation that may be involved in IFN-mediated immunomodulation. Hierarchical clustering showed that patient samples were clearly separated from controls based on their gene expression profile. These results demonstrate that high-density oligonucleotide microarray has the potential to explore the mechanism of pathogenesis of systemic lupus erythematosus.

Adolescent↗

["Standards, Options and Recommendations 2001" for radiotherapy in patients with non-metastatic infiltrating breast cancer. Update. National Federation of Cancer Campaign Centers (FNCLCC)].

CONTEXT: The "Standards, Options and Recommendations" (SOR) project, started in 1993, is a collaboration between the Federation of french cancer centers (FNCLCC), the 20 french cancer centers, and specialists from french public universities, general hospitals and private clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and the outcome of cancer patients. The methodology is based on a literature review and critical appraisal by a multidisciplinary group of experts, with feedback from specialists in cancer care delivery. OBJECTIVES: To develop clinical practice guidelines for non metastatic breast cancer patients according to the definitions of the Standards, Options and Recommendations project. METHODS: Data were identified by searching Medline, web sites, and using the personal reference lists of members of the expert groups. Once the guidelines were defined, the document was submitted for review to 148 independent reviewers. RESULTS: This article presents the chapter radiotherapy resulting from the 2001 update of the version first published in 1996. The modified 2001 version of the standards, options and recommendations takes into account new information published. The main recommendations are: (1) Breast irradiation after conservative surgery significantly decrease the risk of local recurrence (level of evidence A) and the decrease in the risk of local recidive after chest wall irradiation is greater as the number of risk factors for local recurrence increases (level of evidence A). (2) After conservative surgery, a whole breast irradiation should be performed at a minimum dose of 50 Gy in 25 fractions (standard, level of evidence A). (3) A boost in the tumour bed should be performed in women under 50 years, even if the surgical margins are free (standard, level of evidence B). (4) Internal mammary chain irradiation is indicated for internal or central tumours in the absence of axillary lymph node involvement (expert agreement) and in the presence of lymph node involvement (standard, level of evidence B1). (5) Sub- and supra-claviculr lymph node irradiation is indicated in patients with axillary node involvement (standard, level of evidence B1).

Adult↗

Blocks of limited haplotype diversity revealed by high-resolution scanning of human chromosome 21.

Global patterns of human DNA sequence variation (haplotypes) defined by common single nucleotide polymorphisms (SNPs) have important implications for identifying disease associations and human traits. We have used high-density oligonucleotide arrays, in combination with somatic cell genetics, to identify a large fraction of all common human chromosome 21 SNPs and to directly observe the haplotype structure defined by these SNPs. This structure reveals blocks of limited haplotype diversity in which more than 80% of a global human sample can typically be characterized by only three common haplotypes.

Algorithms↗

Hypermethylation of CpG islands in the mouse asparagine synthetase gene: relationship to asparaginase sensitivity in lymphoma cells. Partial methylation in normal cells.

We have sequenced the promoter region of the murine asparagine synthetase gene and examined its methylation profile in the CpG islands of L-asparaginase-sensitive 6C3HED cells (asparagine auxotrophs) and resistant variants (prototrophs). In the former, complete methylation of the CpG island is correlated with failure of expression of mRNA: cells of the latter possess both methylated and unmethylated alleles, as do cells of the intrinsically asparagine-independent lines L1210 and EL4. A similar phenomenon was seen in normal splenic cells of adult mice. This was age related: no methylation was found in weanlings, but up to 45% of gene copies in animals 18 weeks or older were methylated. It was also tissue related, with methylation occurring rarely in liver cells. The relationship of these changes to oncogenesis is considered.

Animals↗

Waiting time for breast cancer surgery in Quebec.

BACKGROUND: Currently there is no agreement on the optimal time to treatment of breast cancer; however, given the considerable emphasis on early detection, one would expect a similar emphasis on early treatment. The purpose of our study was to assess the time interval to surgery from initiation of diagnosis among Quebec women with breast cancer and to examine the influence on waiting time of age, pattern of care and cancer stage. METHODS: Records of physician fee-for-service claims and of hospital admissions were obtained for all Quebec women who underwent an invasive procedure for the diagnosis or treatment of breast cancer between 1992 and 1998. Waiting time was calculated as the number of days between the first diagnostic procedure and surgical treatment. RESULTS: There were 29,606 episodes of breast cancer surgery among 28,100 women: 5922 mastectomies and 23,684 lumpectomies. The absolute number of episodes of breast cancer treated with surgery rose from 3626 in 1992 to 5162 in 1998. The overall median waiting time was 34 days (interquartile range [IQR] 19-62); 13.5% of the women waited longer than 90 days. The median waiting time rose from 29 days (IQR 15-54) in 1992 to 42 days (IQR 24-72) in 1998, representing a relative increase of 37% (95% confidence interval [CI] 32%-43%) after adjusting for age and cancer stage. The median waiting time increased with the number of diagnostic procedures, from 24 days (IQR 14-42) with 1 procedure to 48 days (IQR 27-84) with 3 procedures to 72 days (IQR 43-121) with 4 procedures, representing adjusted relative increases of 97% (95% CI 91%-103%) and 194% (95% CI 181%-208%), respectively. The proportion of women receiving 3 or more diagnostic procedures before surgery increased steadily over the study period, from 19.2% in 1992 to 33.0% in 1998. The median waiting time was shorter with more advanced stages of cancer: 53 days (IQR 30-86) for carcinoma in situ, 35 (IQR 20-62) for localized disease, 28 (IQR 16-49) for regional disease and 24 (IQR 11-52) for disseminated disease. INTERPRETATION: Waiting time between initial diagnosis and first surgery for breast cancer has increased substantially in Quebec between 1992 and 1998. Possible explanations include increased demand, decreased resources and changes in patterns of care.

Adult↗

[A study of the hereditary susceptibility of HLA-DQA1 to essential hypertension, athrothrombotic brain infarction and lacunar stroke].

OBJECTIVE: To study the types of HLA-DQA1 alleles in patients with essential hypertension (EH), athrothrombotic brain infarction (ABI) and lacunar stroke (LS) and normal control individuals and the hereditary susceptibility of HLA-DQA1 alleles to those diseases. METHODS: The allelic typing of HLA-DQA1 was detected by PCR-SSP in 155 cases of EH, ABI and LS and 64 normal individuals. RESULTS: The frequencies of HLA-DQA1 * 0301 in EH, ABI and LS groups were obviously higher than that in normal control group (33.6538 vs. 17.9688, 36.5884 vs. 17.9688, 33.0645 vs. 17.9688, P < 0.01). The frequencies of HLA-DQA1 * 0103 in groups of EH, ABI, LS, ABI with EH, and LS with EH were lower than that in the normal control group (6.7308 vs17.1875, RR = 0.3916, P < 0.01; 6.0976 vs. 17.1875, RR = 0.3548, P < 0.05; 6.4566 vs17.1875, RR = 0.3754, P < 0.01; 2.3809 vs17.1875, RR = 0.1385, P < 0.01; 3.5714 vs. 17.1875, RR = 0.2078, P < 0.01. CONCLUSION: HLA-DQA1 * 0301 allele may be a correlative gene with hereditary susceptibility of EH, ABI and LS, and HLA-DQA1 * 0103 allele may be a protective gene of those diseases.

Adult↗

Role of distal zinc finger of nucleocapsid protein in genomic RNA dimerization of human immunodeficiency virus type 1; no role for the palindrome crowning the R-U5 hairpin.

Genomic RNA isolated from HIV-1 variously mutated in nucleocapsid protein (NC) was characterized by nondenaturing gel electrophoresis. Mutations in the C-terminal, the N-terminal, and the linker regions had no effect on genomic RNA dimerization [they are R7R10K11S, P31L, R32G, S3(32-34), and K59L], while a C36S/C39S mutation in the distal zinc knuckle (Cys-His box or zinc finger) inhibited genome dimerization as much as disrupting the kissing-loop domain. The four mutations which inhibited tRNA(Lys3) genomic placement (i.e., the in vivo placement of tRNA(Lys3) on the primer binding site) had no effect on genome dimerization. Among five mutations which inhibited genome packaging, four had no effect on genome dimerization. Thus the N-terminal and linker regions of NC control genome packaging/tRNA(Lys3) placement (two processes which do not require mature NC) but have little influence on genome dimerization and 2-base extension of tRNA(Lys3) (two processes which are likely to require mature NC). It has been suggested, based on electron microscopy, that the AAGCUU82 palindrome crowning the R-U5 hairpin stimulates genomic RNA dimerization. To test this hypothesis, we deleted AGCU81 from wild-type viruses and from viruses bearing a disrupted kissing-loop hairpin or kissing-loop domain; in another mutant, we duplicated AGCU81. The loss of AGCU81 reduced dimerization by 2.5 +/- 4%; its duplication increased it by 3 +/- 6%. Dissociation temperature was left unchanged. We reach two conclusions. First, the palindrome crowning the R-U5 hairpin has no impact on HIV-1 genome dimerization. Second, genomic RNA dimerization is differentially influenced by NC sequence: it is Zn finger dependent but independent of the basic nature of the N-terminal and linker subdomains. We propose that the NC regions implicated in 2-base extension of tRNA(Lys3) are required for a second (maturation) step of tRNA placement. Genome dimerization and mature tRNA placement would then become two RNA-RNA interactions sharing similar NC sequence requirements.

Amino Acid Sequence↗

Role of stem B, loop B, and nucleotides next to the primer binding site and the kissing-loop domain in human immunodeficiency virus type 1 replication and genomic-RNA dimerization.

Stem-loop B is a 12-nucleotide [nt]-long completely conserved sequence postulated to form a 4-bp stem and a 4-nt internal loop under the kissing-loop hairpin (klh) (nt 248 to 270) of human immunodeficiency virus type 1 (HIV-1) genomic RNA. We investigated its role in viral replication, genomic RNA dimerization, and dimerization of partial HIV-1 RNA transcripts. The putative CUCG246-CGAG277 duplex was replaced by nine alternative complementary sequences, five likely to base pair only in short RNAs and four likely to base pair in long (approximately 500-nt) RNAs, as assessed by the algorithm mfold. Among the five former sequences, none preserved genome dimerization and all reduced viral replication by 98 to 99.9%. Among the four latter sequences, three (MB6, -9, and -10) preserved genome dimerization, one (MB7) did not significantly inhibit it, and two (MB9 and -10) preserved viral replication. We conclude that duplex formation by stem B nucleotides is necessary for viral infectivity and complete genome dimerization. Deleting the 5' or 3' side of loop B or of stem B had little impact on dimerization of partial RNA transcript and no impact on klh folding (and, for loop B mutations, on stem B folding), but each deletion inhibited genome dimerization almost as much as klh destruction. This suggests that loop B is required for complete genome dimerization and that loop B and stem B stimulate dimerization only in very long RNAs and/or in the presence of unidentified viral and cellular factors. Finally, we asked if nine deletions or nucleotide substitutions within nt 200 to 242 and/or nt 282 to 335 could influence genome dimerization. These mutations had intermediate inhibitory impacts consistent with their predicted influence on stem B, loop B, and klh formation. Two exceptions were Delta200-226 and Delta236-242 genomic RNAs, which dimerized relatively poorly despite having neutral or positive influences on stem B, loop B, and klh folding.

Animals↗

[A study of association between atherothrombotic brain infarction and HLA-DQA1 peptide binding motifs].

OBJECTIVE: To analyze the hereditary susceptibility for HLA-DQA1 alleles according to trait of multiple genes leading to disease in atherothrombotic brain infarction (ABI). METHODS: HLA-DQA1 alleles in ABI patients (n=81) and healthy controls (n=99) were detected by PCR-SSP techniques. RESULTS: (1)The frequency of HLA-DQA1*0301 was significantly higher in ABI patients. (2)The frequency of HLA-DQA1*0301 was significantly higher in patients with family history of essential hypertension (EH). (3)The frequency of HLA-DQA1*0103 was significantly lower in ABI patients. CONCLUSION: HLA-DQA1*0301 allele might be a correlative gene with hereditary susceptibility of ABI and HLA-DQA1*0301 allele might be a correlative gene in ABI patients with the family history of essential hypertension, whereas HLA-DQA1*0103 allele might be a protective gene in the patients with ABI.

Aged↗

[Study on the muscarinic receptor and its subtypes in patients with chronic obstructive pulmonary disease].

OBJECTIVE: To investigate the M receptor and its subtypes in the lung tissue of patients with chronic obstructive pulmonary disease (COPD). METHODS: Muscarinic cholinergic receptors have been identified and characterized by radioligand binding assay in the lung tissue specimens of patients with COPD. Competitive binding experiments with pirenzepine and methoctramine were used to characterize muscarinic subtypes. RESULTS: The contents of M-receptor were (64 +/- 10), (42 +/- 18) fmol/mg. protein in normal group and COPD patients respectively. No significant difference was observed in antagonist affinity (K(D)) among normal group and COPD patients. The ratio of subtype M(1) was higher in COPD patients (67.2 +/- 2.7)% than in normal group (74.2 +/- 4.8)%, M(2) was lower [(29.3 +/- 1.7)% vs (16.8 +/- 4.4)%] and M(3) was higher [(3.6 +/- 2.9) % vs (9.3 +/- 4.1)%] respectively. CONCLUSION: The number of muscarinic cholinergic receptors is decreased in COPD patients, but the ratios of subtype M(1) and M(3) are increased and the subtype M(2) is decreased. The changes of the distribution of the subtypes of M-receptors is an important pathophysiologic change of COPD.

Female↗

Cardiorespiratory responses to fatiguing dynamic and isometric hand-grip exercise.

In occupational work, continuous repetitive and isometric actions performed with the upper extremity primarily cause local muscle strain and musculoskeletal disorders. They may also have some adverse effects on the cardiorespiratory system, particularly, through the elevation of blood pressure. The aim of the present study was to compare peak cardiorespiratory responses to fatiguing dynamic and isometric hand-grip exercise. The subjects were 21 untrained healthy men aged 24-45 years. The dynamic hand-grip exercise (DHGE) was performed using the left hand-grip muscles at the 57 (SD 4)% level of each individual's maximal voluntary contraction (MVC) with a frequency of 51 (SD 4) grips x min(-1). The isometric hand-grip exercise (IHGE) was done using the right hand at 46 (SD 3)% of the MVC. The endurance time, ventilatory gas exchange, heart rate (HR) and blood pressure were measured during both kinds of exercise. The mean endurance times for DHGE and IHGE were different, 170 (SD 62) and 99 (SD 27) s, respectively (P < 0.001). During DHGE the mean peak values of the breathing frequency [20 (SD 6) breaths x min(-1)] and tidal volume [0.89 (SD 0.34) l] differed significantly (P < 0.01) from peak values obtained during IHGE [15 (SD 5) breaths x min(-1) and 1.14 (SD 0.32) l, respectively]. The corresponding peak oxygen consumptions, pulmonary ventilations, HR and systolic blood pressures did not differ, and were 0.51 (SD 0.06) and 0.46 (SD 0.11) l x min(-1), 17.1 (SD 3.0) and 16.7 (SD 4.7) l x min(-1), 103 (SD 18) and 102 (SD 17) beats x min(-1), and 156 (SD 17) and 161 (SD 17) mmHg, respectively. The endurance times of both DHGE and IHGE were short (< 240 s). The results indicate that the peak responses for the ventilatory gas exchange, HR and blood pressure were similar during fatiguing DHGE and IHGE, whereas the breathing patterns differed significantly between the two types of exercise. The present findings emphasize the importance of following ergonomic design principles in occupational settings which aim to reduce the output of force, particularly in tasks requiring isometric and/or one-sided repetitive muscle actions.

Adult↗

Sodium phosphate enhances plasmid DNA expression in vivo.

Intramuscular injection of plasmid DNA results in myofiber cell expression of proteins encoded by the DNA. The preferred vehicle for plasmid DNA injections has been saline (154 mM sodium chloride) or PBS (154 mM NaCl plus 10 mM sodium phosphate). Here, it is shown that injection of luciferase or beta-galactosidase encoding plasmid DNA in a 150 mM sodium phosphate vehicle into murine muscle resulted in a two- to seven-fold increase in transgene expression compared with DNA injected in saline or PBS. When the DNA encoded secreted alkaline phosphatase, preproinsulin or interferon, sodium phosphate vehicle increased their serum levels by two- to four-fold. When the DNA encoded mouse erythropoietin, sodium phosphate vehicle increased hematocrits by two-fold compared with DNA injected in saline. When the DNA encoded influenza nucleoprotein, sodium phosphate increased anti-nucleoprotein antibody titers by two-fold. The expression of luciferase from plasmid DNA instilled into lung was increased five-fold compared with that in vehicle without sodium phosphate. Incubation of plasmid DNA with muscle extract or serum showed that sodium phosphate protected the DNA from degradation. Thus, a change from sodium chloride to sodium phosphate vehicle can enhance the expression of plasmid DNA in a tissue, possibly by inhibiting DNA degradation. Gene Therapy (2000) 7, 1171-1182.

Alkaline Phosphatase↗

Impact of human immunodeficiency virus type 1 RNA dimerization on viral infectivity and of stem-loop B on RNA dimerization and reverse transcription and dissociation of dimerization from packaging.

The kissing-loop domain (KLD) encompasses a stem-loop, named kissing-loop or dimerization initiation site (DIS) hairpin (nucleotides [nt] 248 to 270 in the human immunodeficiency virus type 1 strains HIV-1(Lai) and HIV-1(Hxb2)), seated on top of a 12-nt stem-internal loop called stem-loop B (nt 243 to 247 and 271 to 277). Destroying stem-loop B reduced genome dimerization by approximately 50% and proviral DNA synthesis by approximately 85% and left unchanged the dissociation temperature of dimeric genomic RNA. The most affected step of reverse transcription was plus-strand DNA transfer, which was reduced by approximately 80%. Deleting nt 241 to 256 or 200 to 256 did not reduce genome dimerization significantly more than the destruction of stem-loop B or the DIS hairpin. We conclude that the KLD is nonmodular: mutations in stem-loop B and in the DIS hairpin have similar effects on genome dimerization, reverse transcription, and encapsidation and are also "nonadditive"; i.e., a larger deletion spanning both of these structures has the same effects on genome dimerization and encapsidation as if stem-loop B strongly impacted DIS hairpin function and vice versa. A C258G transversion in the palindrome of the kissing-loop reduced genome dimerization by approximately 50% and viral infectivity by approximately 1.4 log. Two mutations, CGCG261-->UUAA261 (creating a weaker palindrome) and a Delta241-256 suppressor mutation, were each able to reduce genome dimerization but leave genome packaging unaffected.

Animals↗

The relationship between Th1/Th2-type cells and disease activity in patients with systemic lupus erythematosus.

OBJECTIVE: To investigate the imbalance of Th1/Th2-type cytokines in patients with systemic lupus erythematosus (SLE) and its relation to disease activity. METHODS: Intracellular cytokines were determined by flow-cytometry following whole-blood culture. RESULTS: Patients with systemic lupus erythematosus disease activity index (SLEDAI) > 10 had statistically significantly fewer CD4+ or CD8+ T cells producing IFN-gamma than patients with SLEDAI = 0, SLEDAI 1-10 or healthy controls (P < 0.01, P < 0.01 or P < 0.05, respectively). Patients with SLEDAI > 10 also had decreased ratio of IFN-gamma/IL-4 positive CD4+ or CD8+ T cells, compared with patients with SLEDAI = 0, SLEDAI 1-10 or healthy controls (P < 0.05). The decreased Th1 or Tc1 cells and the ratios of IFN-gamma: IL-4 positive CD4+ T-cells were significantly correlated with disease activity (P < 0.05). CONCLUSION: SLE is characterized by an imbalance of Th1/Th2 and Tc1/Tc2 cytokines. The decreased Th1 or Tc1 cells and the Th1/Th2 ratio are related to disease activity.

Adult↗