Design of continuous circulation sub for gas drilling and the mechanical analysis on the sub body

AbstractGas drilling, as an important part of underbalanced drilling, can increase drilling speed. But in the process of conventional gas drilling, it tends to cause cutting settlement, borehole collapse, sticking and other safety hazards because gas circulation has to be interrupted. Therefore, this paper presents a continuous circulation sub which can be installed and removed easily. With this sub, gas circulation will not be interrupted when drilling tools are connected and removed. This sub is composed of body, main valve, bypass valve and side entry sub. The structure design of its key components (i.e. main and bypass valves) were fulfilled. Based on statics analysis on the sub body, its force situations under extension, torsion and internal pressure were simulated by using the ANSYS finite element analysis software. It is shown that its stress distribution trend is consistent with its elastic–plastic mechanics analysis results. Stress concentrates around the two round holes of the sub body, and the maximum deformation amount is still at the stage of elastic deformation. The analysis results are in line with the elastic–plastic mechanics analysis results, and the requirement of body strength is satisfied. This paper provides a new program to guarantee the drilling safety of extended-reach wells, underbalanced wells and narrow-density window wells

Translation of mouse model to human gives insights into periodontitis etiology

To suggest candidate genes involved in periodontitis, we combined gene expression data of periodontal biopsies from Collaborative Cross (CC) mouse lines, with previous reported quantitative trait loci (QTL) in mouse and with human genome-wide association studies (GWAS) associated with periodontitis. Periodontal samples from two susceptible, two resistant and two lines that showed bone formation after periodontal infection were collected during infection and naïve status. Differential expressed genes (DEGs) were analyzed in a case-control and case-only design. After infection, eleven protein-coding genes were significantly stronger expressed in resistant CC lines compared to susceptible ones. Of these, the most upregulated genes were MMP20 (P = 0.001), RSPO4 (P = 0.032), CALB1 (P = 1.06×10-4), and AMTN (P = 0.05). In addition, human orthologous of candidate genes were tested for their association in a case-controls samples of aggressive (AgP) and chronic (CP) periodontitis (5,095 cases, 9,908 controls). In this analysis, variants at two loci, TTLL11/PTGS1 (rs9695213, P = 5.77×10-5) and RNASE2 (rs2771342, P = 2.84×10-5) suggested association with both AgP and CP. In the association analysis with AgP only, the most significant associations were located at the HLA loci HLA-DQH1 (rs9271850, P = 2.52×10-14) and HLA-DPA1 (rs17214512, P = 5.14×10-5). This study demonstrates the utility of the CC RIL populations as a suitable model to investigate the mechanism of periodontal disease

Fine mapping of quantitative trait loci using advanced intercross lines of mice and positional cloning of the corresponding genes

High-resolution mapping of quantitative trait loci (QTLs) is an essential step towards positional cloning and identification of the corresponding genes. Most QTL detection and mapping studies in mice have been carried out using F2 intercross and backcross populations. As a consequence of the limited number of recombination events in small chromosomal regions, this has generally permitted mapping to only relatively large confidence intervals of 20 to 40 cM. A number of po pulation designs have been proposed to increase recombination level in crosses. This includes advanced intercross lines (AIL) described by Daruasi and Soller (Genomics. 1995; 141: 1199-1207). In this report demonstration of the utility of the AIL approach for fine mapping of QTL, which previously had been mapped with 95 % confidence interval to 20 to 40 cM in a F2 intercross, will be presented. The methodological approaches to go from the fine-mapped QTL to the identification of the actual genes and mutations are discussed

Cloning and sequencing of the Tnfa genes of three inbred mouse strains

The C57BL/6 BALB/c and A/J inbred laboratory mouse strains often express different response phenotypes when challenged with a variety of infectious agents (Morrison et al. 1978; Bradley 1977; Hormmaeche et al. 1985). In view of the pivotal role of tumor necrosis factor Tnfa in innate immunity, we determined the nucleotide sequence of genomic Tnfa DNA of these three mouse strains. Genomic DNA of the three mouse strains C57BL/6, BALB/c, and A/J was obtained from the Jackson Laboratory (Bar Harbor, ME). The DNA was amplified by the polymerase chain reaction (PCR; Seiki et al. 1988) with primers designed from the promoter and the 3' untranslated (UTR) regions of the published sequence of the C57BL/6 Tnfa gene (Semon et al. 1987). The PCR amplifications were carried out as described earlier (Maga and Richarson 1991). Figure 1 shows the PCR amplification products of the genomic DNAs of the three mouse strains. The amplified products were of the expected size [(approximately 3800 base pairs (bp)]. The PCR-amplified DNAs were cloned in the pMOS vector, using the pMOS Blue T-vector Kit (Amersham, Little Chalfont, England). The nucleotide sequence of the cloned DNA was determined on both strands of each product with the ficomole Sequencing Kit (Strategene, La Jolla, CA). The complete DNA sequences of the clones were determined using internal primers for sequencing reactions based on the published sequence of the mouse Tnfa gene. The complete DNA sequence of the Tnfa genes of the three mouse strains is illustrated. A number of sequence polymorphisms are apparent at different locations in the genes. Point mutations were found in the introns and exons. A major polymorphism differentiating all three mouse strains was revealed in the microsatellite (AC)n located in the promoter region. [This microsatellite was referred to as a poly (A) repeat by Semon and co-workers (1987)]. A 4 bp deletion was found in the first intron in the A/J strain by comparison with the BALB/c and C57BL/6, while a 3 bp deletion was found in the first intron in the C57BL/6 by comparison with the A/J and BALB/c sequences. A single point mutation in each of the first two exons differentiated the A/J from the other two strains. These mutations would specify Ile in the first exon and Thr in the second exon of the A/J gene and Thr and Ala in these exons, respectively, in the BALB/c and C57BL/6 strains. The polyadenylating signal and the TTATTTAT elements in the 3'UTR, which have been reported to reduce the stability of the mRNA (Shaw and Kamen 1986), are conserved among the three strains

Polymorphisms in the TNFa but not in TNFb microsatellite and correlation with trypanosomiasis in mice

The tumor necrosis factor (TNF) locus comprises the tandemly arranged genes coding for Tnfa (cachectin)and Tnfb (lymphotoxin-alpha) (Semon et al. 1987). In mice, the TNF locus is located on chromosome 17 (MMU17) in the major histocompatibility complex (MHC)region. Tnfa and soluble lymphotoxin alpha are cytokines with similar biological activities

Polymorphism in the microsatellite located in the promoters of the Tnfa and Tnfb genes of different mouse strains

The tumor necrosis factor (TNF) locus comprises the tandemly arranged genes coding for Tnfa (cachectin) and Tnfb (lymphotoxin-alpha) (Semon et al 1987). In mice, the TNF locus is located on chromosome 17 (MMU17) in the major histocompatibility complex (MHC) region. Tnfa and soluble lymphotoxin alpha are cytokines with similar biological activities. Tnfa, a pleiotropic cytokine that is predominatly produced by activated macrophages (Beutler et al 1985) exerts diverse effects on a wide variety of cells including tumor cells lymphocytes fibroblasts and endothelial cells (Beutler and Cerami 1989). Tnfa has also been shown to play an important role in inflammatory immunoregulatory proliferative and antiviral responses and to be important during infection with various protozoan parasites (Beulter and Cerami 1989). Recently we cloned and sequenced the Tnfa genes of three inbred mouse strains. A/J. BALB/C and C57BL/6 (Iraqi and Teale 1997). A polymorphism differentiating the C57BL/6 from the A/J and BALB/C strains was found in the microsatellite (AC)n located in the promoter region. This microsatellite was referred to as a poly (A) repeat by Semon and co-workers (1987). In the latter study a (TC)n microsatellite was reported in the Tnfb promoter. It was suggested that microsatellite repeats in general may be involved in regulation of gene expression (Hamada et al 1982: Lue et al 1989). Moreover it has been observed that increaed repeat lengths of the mi-crosatellite in promoter regions is associated with in-creased gene transcription (Hamada et al 1984). These observations have suggested that the microsatellite may act as enhancer elements or upstream activation sequences (UASs). Here we report length variation in the micro-setellites located in the promoters of the Tnfa and Tnfb genes of 12 mouse strains. Genomic DNA of all 12 strains (C57BL/10J, C57BL/6J, C57B/SgSnj, AKR/A, C3H/Hej, BALB/C, DBA/1J, 129J SWR/J, DBA/2J, A/WySnJ and A/J was obtained from the Jackson Laboratory (Bar Harbor Me)

Polymorphisms, in the Tnfa gene of different inbred mouse strains

In view of the Tnfa gene location within the major histocompatibility (MHC) region and reports of its importance in disease protection activity, this paper examines the TNF a genes of a number of different mouse strains which were known to be of different disease response phenotypes. Twelve inbred mouse strains were studied. In a separate study, the repeat length in the (CA) n microsatellite located within the Tnfa promoter region of these 12 inbred mouse strains was determined, High relative molecular mass genomic (chramosomal) DNA of the inbred mouse strains was obtained from the Jackson Laboratory. The results of the study shows that pCR-RFLps were not detected in the promoter region. Two haplotypes were defined in the first intron and three haplotypes could be defined in 3 UTR in the 12 strains based on PCR-RFLP genotypes and, moreover, these were not strictly concordant with serologically defined H2 haplotypes