Viral Dose and Immunosuppression Modulate the Progression of Acute BVDV-1 Infection in Calves: Evidence of Long Term Persistence after Intra-Nasal Infection

Bovine viral diarrhoea virus (BVDV) infection of cattle causes a diverse range of clinical outcomes from being asymptomatic, or a transient mild disease, to producing severe cases of acute disease leading to death. Four groups of calves were challenged with a type 1 BVDV strain, originating from a severe outbreak of BVDV in England, to study the effect of viral dose and immunosuppression on the viral replication and transmission of BVDV. Three groups received increasing amounts of virus: Group A received 10^2.55TCID₅₀/ml, group B 10^5.25TCID₅₀/ml and group C 10^6.7TCID ₅₀/ml. A fourth group (D) was inoculated with a medium dose (10^5.25TCID₅₀/ml) and concomitantly treated with dexamethasone (DMS) to assess the effects of chemically induced immunosuppression. Naïve calves were added as sentinel animals to assess virus transmission. The outcome of infection was dose dependent with animals given a higher dose developing severe disease and more pronounced viral replication. Despite virus being shed by the low-dose infection group, BVD was not transmitted to sentinel calves. Administration of dexamethasone (DMS) resulted in more severe clinical signs, prolonged viraemia and virus shedding. Using PCR techniques, viral RNA was detected in blood, several weeks after the limit of infectious virus recovery. Finally, a recently developed strand-specific RT-PCR detected negative strand viral RNA, indicative of actively replicating virus, in blood samples from convalescent animals, as late as 85 days post inoculation. This detection of long term replicating virus may indicate the way in which the virus persists and/or is reintroduced within herds.     

Independent Association of Postdoctoral Training with Subsequent Careers in Cancer Prevention

The purpose of this study was to examine the career paths of alumni from the National Cancer Institute (NCI) Cancer Prevention Fellowship Program (CPFP), a structured in-house postdoctoral training program of 3–4 years duration, and specifically what proportion of the alumni were currently performing cancer prevention-related activities. The analyses here included 119 CPFP alumni and 85 unsuccessful CPFP applicants, all of whom completed postdoctoral training between 1987–2011 and are currently employed. Postdoctoral training experiences and current career outcomes data were collected via online surveys. Differences between groups were assessed using chi-square and Fisher’s exact test p-values and subsequent regression analyses adjusted for differences between the groups. Compared to 15.3% of unsuccessful CPFP applicants, 52.1% of CPFP alumni (odds ratio [OR] = 4.99, 95% confidence interval [95% CI): 1.91–13.0) were currently spending the majority of their time working in cancer prevention. Among those doing any cancer prevention-focused work, 54.3% of CPFP alumni spent the majority of their time performing cancer prevention research activities when compared to 25.5% of unsuccessful applicants (OR = 4.26, 95% CI: 1.38–13.2). In addition to the independent effect of the NCI CPFP, scientific discipline, and employment sector were also associated with currently working in cancer prevention and involvement in cancer prevention research-related activities. These results from a structured postdoctoral training program are relevant not only to the cancer prevention community but also to those interested in evaluating alignment of postdoctoral training programs with available and desired career paths more broadly.     

Amino Alcohol- (NPS-2143) and Quinazolinone-Derived Calcilytics (ATF936 and AXT914) Differentially Mitigate Excessive Signalling of Calcium-Sensing Receptor Mutants Causing Bartter Syndrome Type 5 and Autosomal Dominant Hypocalcemia

Introduction

Activating calcium sensing receptor (CaSR) mutations cause autosomal dominant hypocalcemia (ADH) characterized by low serum calcium, inappropriately low PTH and relative hypercalciuria. Four activating CaSR mutations cause additional renal wasting of sodium, chloride and other salts, a condition called Bartter syndrome (BS) type 5. Until today there is no specific medical treatment for BS type 5 and ADH. We investigated the effects of different allosteric CaSR antagonists (calcilytics) on activating CaSR mutants.

Methods

All 4 known mutations causing BS type 5 and five ADH mutations were expressed in HEK 293T cells and receptor signalling was studied by measurement of intracellular free calcium in response to extracellular calcium ([Ca²⁺]_o). To investigate the effect of calcilytics, cells were stimulated with 3 mM [Ca²⁺]_o in the presence or absence of NPS-2143, ATF936 or AXT914.

Results

All BS type 5 and ADH mutants showed enhanced signalling activity to [Ca²⁺]_o with left shifted dose response curves. In contrast to the amino alcohol NPS-2143, which was only partially effective, the quinazolinone calcilytics ATF936 and AXT914 significantly mitigated excessive cytosolic calcium signalling of all BS type 5 and ADH mutants studied. When these mutants were co-expressed with wild-type CaSR to approximate heterozygosity in patients, ATF936 and AXT914 were also effective on all mutants.

Conclusion

The calcilytics ATF936 and AXT914 are capable of attenuating enhanced cytosolic calcium signalling activity of CaSR mutations causing BS type 5 and ADH. Quinazolinone calcilytics might therefore offer a novel treatment option for patients with activating CaSR mutations.     

Reduction in hybrid single muscle fiber proportions with resistance training in humans.

The purpose of this investigation was to examine the effects of 12 wk of progressive resistance training (PRT) on single muscle fiber myosin heavy chain (MHC; I, I/IIa, I/IIa/IIx, IIa, IIa/IIx, IIx) isoform proportions in young individuals. Young, untrained men (YM; n = 6) and women (YW; n = 6) (age = 22 +/- 1 and 25 +/- 2 yr for YW and YM, respectively) received pre- and post-PRT muscle biopsies from the right vastus lateralis for single muscle fiber MHC distribution by electrophoretic analysis (192 +/- 5 pre- and 183 +/- 6 post-fibers/subject analyzed; 4,495 fibers total). Data are presented as percentages of the total fibers analyzed per subject. The PRT protocol elicited an increase in the pure MHC IIa (Delta = + 24 and + 27; YW and YM, respectively; P < 0.05) with no change in the pure MHC I distribution. The hybrid MHC distributions decreased I/IIa/IIx (Delta = -2; YM and YW; P < 0.05), IIa/IIx (Delta = -13 and -19 for YM and YW, respectively; P < 0.05), and total hybrid fiber proportion (I/IIa + I/IIa/IIx + IIa/IIx) decreased (Delta = -19 and -30 for YM and YW, respectively; P < 0.05) with the training, as did the MHC IIx distribution (Delta = -2; YW only; P < 0.05). Alterations in the predominance of MHC isoforms within hybrid fibers (decrease in MHC I-dominant I/IIa and nondominant MHC IIa/IIx, increase in MHC IIa-dominant IIa/IIx; P < 0.05) appeared to contribute to the increase in the MHC IIa proportion. Electrophoresis of muscle cross sections revealed an approximately 7% increase (P < 0.05) in MHC IIa proportion in both groups, whereas the MHC IIx decrease by 7.5 and 11.6% post-PRT in YW and YM, respectively. MHC I proportions increase in YM by 4.8% (P < 0.05) post-PRT. These findings further support previous resistance training data in young adults with respect to the increase in the MHC IIa proportions but demonstrate that a majority of the change can be attributed to the decrease in single-fiber hybrid proportions.     

Development of a predicted physical map of microsatellite locus positions for pinnipeds, with wider applicability to the Carnivora

Understanding genetic variation responsible for phenotypic differences in natural populations is significantly hampered by a lack of genomic data for many species. Levels of variation can, however, be estimated using microsatellite markers, which may be useful for relating individual fitness to genetic diversity. Prior studies have demonstrated correlations between heterozygosity and individual fitness in some species. These correlations are sometimes driven by a subset of markers, and it is unclear whether this is because those markers best reflect genome-wide heterozygosity, or whether they are linked to fitness-related genes. Differentiating between these scenarios is hindered when the genomic location of markers is unknown. Here, we develop a predicted genomic map of pinniped microsatellite loci based on conservation of primary sequence and genomic location between dog, cat and giant panda. We mapped 210 of 260 (81%) microsatellites from pinnipeds to locations in dog, cat and giant panda genomes. Based on the demonstrable synteny between the genomes of closely related taxa within the Carnivora, we use these data to identify those microsatellites with the greatest chance of cross-species amplification success and demonstrate successful amplification of 21 of 26 loci for cat, dog and two seal species. We also demonstrate the potential to identify candidate genes that may underpin the functional relationship with individual fitness. Overall, we show that this approach provides a rapid and robust method to elucidate genome organisation for nonmodel organisms and have established a resource that facilitates further genetic research on pinnipeds that also has wider applicability to other carnivores.     

Single muscle fiber adaptations to resistance training in old (>80 yr) men: evidence for limited skeletal muscle plasticity

The purpose of this study was to investigate whole muscle and single muscle fiber adaptations in very old men in response to progressive resistance training (PRT). Six healthy independently living old men (82 +/- 1 yr; range 80-86 yr, 74 +/- 4 kg) resistance-trained the knee extensors (3 sets, 10 repetitions) at approximately 70% one repetition maximum 3 days/wk for 12 wk. Whole thigh muscle cross-sectional area (CSA) was assessed before and after PRT using computed tomography (CT). Muscle biopsies were obtained from the vastus lateralis before and after the PRT program. Isolated myosin heavy chain (MHC) I and IIa single muscle fibers (n = 267; 142 pre; 125 post) were studied for diameter, peak tension, shortening velocity, and power. An additional set of isolated single muscle fibers (n = 2,215; 1,202 pre; 1,013 post) was used to identify MHC distribution. One repetition maximum knee extensor strength increased (P < 0.05) 23 +/- 4 kg (56 +/- 4 to 79 +/- 7 kg; 41%). Muscle CSA increased (P < 0.05) 3 +/- 1 cm2 (120 +/- 7 to 123 +/- 7 cm2; 2.5%). Single muscle fiber contractile function and MHC distribution were unaltered with PRT. These data indicate limited muscle plasticity at the single-muscle fiber level with a resistance-training program among the very old. The minor increases in whole muscle CSA coupled with the static nature of the myocellular profile indicate that the strength gains were primarily neurological. These data contrast typical muscle responses to resistance training in young ( approximately 20 yr) and old ( approximately 70 yr) humans and indicate that the physiological regulation of muscle remodeling is adversely modified in the oldest old.     

Different domains of the RNA polymerase of infectious bursal disease virus contribute to virulence

BACKGROUND: Infectious bursal disease virus (IBDV) is a pathogen of worldwide significance to the poultry industry. IBDV has a bi-segmented double-stranded RNA genome. Segments A and B encode the capsid, ribonucleoprotein and non-structural proteins, or the virus polymerase (RdRp), respectively. Since the late eighties, very virulent (vv) IBDV strains have emerged in Europe inducing up to 60% mortality. Although some progress has been made in understanding the molecular biology of IBDV, the molecular basis for the pathogenicity of vvIBDV is still not fully understood. METHODOLOGY, PRINCIPAL FINDINGS: Strain 88180 belongs to a lineage of pathogenic IBDV phylogenetically related to vvIBDV. By reverse genetics, we rescued a molecular clone (mc88180), as pathogenic as its parent strain. To study the molecular basis for 88180 pathogenicity, we constructed and characterized in vivo reassortant or mosaic recombinant viruses derived from the 88180 and the attenuated Cu-1 IBDV strains. The reassortant virus rescued from segments A of 88180 (A88) and B of Cu-1 (BCU1) was milder than mc88180 showing that segment B is involved in 88180 pathogenicity. Next, the exchange of different regions of BCU1 with their counterparts in B88 in association with A88 did not fully restore a virulence equivalent to mc88180. This demonstrated that several regions if not the whole B88 are essential for the in vivo pathogenicity of 88180. CONCLUSION, SIGNIFICANCE: The present results show that different domains of the RdRp, are essential for the in vivo pathogenicity of IBDV, independently of the replication efficiency of the mosaic viruses.     

Cellular localization of THIK-1 (K(2P)13.1) and THIK-2 (K(2P)12.1) K channels in the mammalian kidney.

K(+)-channels fulfill several important functions in the mammalian kidney such as volume regulation, recirculation and secretion of K(+) ions, and maintaining the resting potential. In this study we used immunocytochemical methods, in situ hybridization, and nephron segment-specific RT-PCR to obtain a detailed picture of the cellular localization of two tandem pore domain potassium (K(2P)) channels, THIK-1 (K(2P)13.1, KCNK13) and THIK-2 (K(2P)12.1, KCNK12). Monospecific antibodies against C-terminal domains of rat THIK-1 and THIK-2 proteins (GST-fusion proteins) were raised in rabbits, freed from cross-reactivity, and affinity purified. All antibodies were validated by Western blot analysis, competitive ELISA, and preabsorption experiments. The expression of THIK channels in specific nephron segments was confirmed by double staining with marker proteins. Results indicate that in rat and mouse THIK-1 and THIK-2 were expressed in the proximal tubule (PT), thick ascending limb (TAL), connecting tubule (CNT), and cortical collecting duct (CCD). In human kidney THIK-1 and THIK-2 were localized in PT, TAL and CCD. Immunostaining of rat tissue revealed an intracellular expression of THIK-1 and THIK-2 throughout the identified nephron segments. However in mouse kidney THIK-2 was identified in basolateral membranes. Overall, the glomerulus, thin limbs and medullary collecting ducts were devoid of THIK-1 and THIK-2 signal. In summary, THIK-1 and THIK-2 are abundantly expressed in the proximal and distal nephron of the mammalian kidney.