Accessibility control of variable region gene assembly during T-cell development

Summary: T-cell development is a complex and ordered process that is regulated in part by the progressive assembly and expression of antigen receptor genes. T cells can be divided into two lineages based on expression of either an αβ or γδ T-cell antigen receptor (TCR), The genes that encode the TCR β and y chains lie in distinct loci, whereas the genes that encode the TCR a and S chains he in a single locos (TCR α/δ locus). Assembly of TCR variable region genes is mediated by a site-specific recombination process that is common among all lymphocytes. Despite the common nature of this process, recombination of TCR genes is tightly regulated within the context of the developing T cell. TCR β, γ and δ variable region genes are assembled prior to TCR α variable region genes. Furthermore, assembly of TCR β variable region genes is regulated within the context of allelic exclusion. The regulation of rearrangement arid expression of genes within the TCR α/δ locus presents a complicated problem. TCR α and δ variable region genes are assembled at different stages of T-cell development, and fully assembled TCR α and δ variable region genes must be expressed in distinct hneages of T cells, αβ and γδ. respectively We have developed several experimental approaches lo assess the role of cis-acting elements in regulating recombination and expression of TCR genes. Here we describe these approaches and discuss our analyses of the regulation of accessibility of the TCR β and TCR α/δ foci during T-cell development.     

Improved Visibility of Metastatic Disease in the Liver During Intra-Arterial Therapy Using Delayed Arterial Phase Cone-Beam CT

Purpose

To compare the visibility of liver metastases on dual-phase cone-beam CT (DP-CBCT) and digital subtraction angiography (DSA), with reference to preinterventional contrast-enhanced magnetic resonance imaging (CE-MRI) of the liver.

Methods

This IRB-approved, retrospective study included 28 patients with neuroendocrine (NELM), colorectal (CRCLM), or sarcoma (SLM) liver metastases who underwent DP-CBCT during intra-arterial therapy (IAT) between 01/2010 and 10/2014. DP-CBCT was acquired after a single contrast agent injection in the tumor-feeding arteries at early and delayed arterial phases (EAP and DAP). The visibility of each lesion was graded by two radiologists in consensus on a three-rank scale (complete, partial, none) on DP-CBCT and DSA images using CE-MRI as reference.

Results

47 NELM, 43 CRCLM, and 16 SLM were included. On DSA 85.1, 44.1, and 37.5 % of NELM, CRCLM, and SLM, were at least partially depicted, respectively. EAP-CBCT yielded significantly higher sensitivities of 88.3 and 87.5 % for CRCLM and SLM, respectively (p < 0.01), but not for NELM (89.4 %; p = 1.0). On DAP-CBCT all NELM, CRCLM, and SLM were visible (p < 0.001). Complete depiction was achieved on DSA for 59.6, 16.3, and 18.8 % of NELM, CRCLM, and SLM, respectively. The complete depiction rate on EAP-CBCT was significantly higher for CRCLM (46.5 %; p < 0.001), lower for NELM (40.4 %; p = 0.592), and similar for SLM (25 %, p = 0.399). On DAP-CBCT however, the highest rates of complete depiction were found—NELM (97.8 %; p = 0.008), CRCLM (95.3 %; p = 0.008), and SLM (100 %; p < 0.001).

Conclusion

DAP-CBCT substantially improved the visibility of liver metastases during IAT. Future studies need to evaluate the clinical impact.

     

The causative agents in infective endocarditis: a systematic review comprising 33,214 cases

Infective endocarditis (IE) incidence remains high with considerable fatality rates; guidelines for prophylaxis against IE are currently under review in some settings which highlights the importance of maintaining up-to-date epidemiological estimates about the most common microbial causes. The objective of this systematic review, following PRISMA guidelines, was to identify the most common microbial causes of IE in recent years. Medline was searched from January 1, 2003 to March 31, 2013 for all articles containing the term “infective endocarditis”. All relevant studies reporting diagnostic results were included. Special patient subpopulations were assessed separately. A total of 105 studies were included, from 36 countries, with available data on a total of 33,214 cases. Staphylococcus aureus was found to be the most common microorganism, being the most frequent in 54.3 % of studies (N?=?57) (and in 55.4 % of studies using Duke’s criteria for diagnosis [N?=?51]). Viridans group streptococci (VGS), coagulase-negative staphylococci (CoNS), Enterococcus spp and Streptococcus bovis were among the most common causes. S. aureus was the most common pathogen in almost all population subgroups; however, this was not the case in patients with implantable devices, prosthetic valves, or immunocompromised non-HIV, as well as in the sub-group from Asia, emphasizing that a global one-size-fits-all approach to the management of suspected IE is not appropriate. This review provides an evidence-based map of the most common causative agents of IE, highlighting S. aureus as the leading cause in the 21st century. The changing epidemiology of IE in some patient sub-groups in the last decade and the very high number of microbiologically undiagnosed cases (26.6 %) suggest the need to revisit IE prophylaxis and diagnostic strategies.     

4-Chloro-m-cresol is a Trigger of Malignant Hyperthermia in Susceptible Swine

Background: 4-Chloro-m-cresol (4-CmC) induces marked contractures in skeletal muscle specimens from individuals susceptible to malignant hyperthermia (MHS). In contrast, 4-CmC induces only small contractures in specimens from normal (MHN) patients. 4-CmC is a preservative within a large number of commercially available drug-preparations (e.g., insulin, heparin, succinylcholine), and it has been suggested that 4-CmC might trigger malignant hyperthermia. This study was designed to investigate the effects of 4-CmC in vivo and in vitro in the same animals.

Methods: After approval of the animal care committee, six Pietrain MHS and six control (MHN) swine were anesthetized with azaperone 4 mg/kg intramuscularly and metomidate 10 mg/kg intraperitoneally. After endotracheal intubation, lungs were mechanically ventilated (inspired oxygen fraction 0.3) and anesthesia was maintained with etomidate 2.5 mg [middle dot] kg-1 [middle dot] h-1 and fentanyl 50 [micro sign]g [middle dot] kg-1 [middle dot] h-1. Animals were surgically prepared with arterial and central venous catheters for measurement of hemodynamic parameters and to obtain blood samples. Before exposure to 4-CmC in vivo, muscle specimens were excised for in vitro contracture tests with 4-CmC in concentrations of 75 and 200 [micro sign]M. Subsequently, pigs were exposed to cumulative administration of 3, 6, 12, 24, and 48 mg/kg 4-CmC intravenously. If an unequivocal episode of malignant hyperthermia occurred, as indicated by venous carbon dioxide concentration >or= to 70 mmHg, pH or= to 2 [degree sign]C, the animals were treated with dantrolene, 3.5 mg/kg.

Results: All MHS swine developed malignant hyperthermia after administration of 4-CmC in doses of 12 or 24 mg/kg. Venous carbon dioxide concentration significantly increased and pH significantly decreased. Temperature increased in all MHS animals more than 2 [degree sign]C. Blood lactate concentrations and creatine kinase levels were significantly elevated. All MHS swine were treated successfully with dantrolene. In contrast, no MHN swine developed signs of malignant hyperthermia. After receiving 4-CmC in a concentration of 48 mg/kg, however, all MHN animals died by ventricular fibrillation. The in vitro experiments showed that both concentrations of 4-CmC produced significantly greater contractures in MHS than in MHN specimens.     

Xenotransplantation. Possibilities of animal breeding]

The pig is the most likely donor organism for xenotransplantation of organs to humans. However, since this constellation is discordant, hyperacute rejection needs to be overcome. This review summarises current strategies of genetically modifying pigs for xenotransplantation. Limitations of the classical method of DNA-microinjection and new perspectives arising from the possibility of cloning animals from cultured cells are discussed.     

Men's attitudes towards a potential vaginal microbicide in Zimbabwe, Mexico and the USA

Vaginal microbicides are being developed in an attempt to expand women's and men's options for protecting themselves against HIV and other sexually transmitted infections. Taking account of men's attitudes during product development and introduction could increase the likelihood that products are acceptable and used. To capture the perspectives of urban and rural men from a range of cultural settings, we conducted focus group discussions with taxi drivers and farmers in Zimbabwe, Mexico and the USA. These explored HIV/STD risk perception and prevention strategies, desirable characteristics of vaginal products and of a microbicide, and attitudes towards use of a potential product. Men were generally supportive of the idea of a microbicide; urban somewhat more than rural men. Most thought microbicides would be preferable to condoms though many raised concerns about potential side effects. The men wanted these products to be as inexpensive and readily available as condoms, and differed as to whether a woman should have permission from her partner to use it. For them to be widely used, the men thought these products must not only be safe and effective, but should also have no negative effect on sexual pleasure. When a product becomes available, introductory messages must explain the limits on its effectiveness and encourage use with condoms. Further research is needed on definitions of pleasurable sex and the ramifications of this for microbicide formulation, and on partner communication around issues of sexuality and prevention of infection.     

Central adiposity in relation to risk of liver cancer in Chinese adults: A prospective study of 0.5 million people

Central adiposity is associated with liver cancer risk beyond general adiposity in Western populations. However, there is little prospective evidence in East Asian populations who are more likely to have central adiposity at given BMI levels. The prospective China Kadoorie Biobank recruited 512,713 adults aged 30–79 years from 10 diverse areas. During 10 years follow-up, 2,847 incident cases of liver cancer were identified. Cox regression was used to estimate adjusted hazard ratios (HR) for liver cancer associated with central adiposity, excluding individuals with cancers and liver diseases at baseline and the first 5 years of follow-up (1,049 incident liver cancer cases). Overall, mean waist circumference (WC) was 82.2 (SD 9.8) cm in men and 79.1 (9.5) cm in women. Central adiposity showed positive associations with liver cancer risk. Associations were strongest for WC and waist-to-hip ratio (WHR), with adjusted HRs per 1-SD of 1.09 (95%CI 1.01–1.18) and 1.12 (1.02–1.23), respectively. The positive associations became stronger when additionally adjusting for BMI (1.26 [1.09–1.46] and 1.14 [1.02–1.28]). The positive association of central obesity (WC ≥90 cm in men and ≥ 80 cm in women) with liver cancer increased progressively with the number of other presenting metabolic risk factors (physical inactivity, diabetes, and hypertension), with HRs of 1.07 (0.90–1.28), 1.17 (1.00–1.38), and 1.91 (1.40–2.59) in those with one, two, and three factors (p for trend 0.006). In this relatively lean Chinese population, there were positive associations of central adiposity with risk of liver cancer, with WHR and WC showing the strongest associations.