Mitochondrial dysfunction in platelets and hippocampi of senescence-accelerated mice

Senescence-accelerated mice (SAM) strains are useful models to understand the mechanisms of age-dependent degeneration. In this study, measurements of the mitochondrial membrane potential (Δψ_m) of platelets and the Adenosine 5^′-triphosphate (ATP) content of hippocampi and platelets were made, and platelet mitochondria were observed in SAMP8 (faster aging mice) and SAMR1 (aging resistant control mice) at 2, 6 and 9 months of age. In addition, an Aβ-induced (Amyloid beta-protein) damage model of platelets was established. After the addition of Aβ, the Δψ_m of platelets of SAMP8 at 1and 6 months of age were measured. We found that platelet Δψ_m, and hippocampal and platelet ATP content of SAMP8 mice decreased at a relatively early age compared with SAMR1. The platelets of 6 month-old SAMP8 showed a tolerance to Aβ-induced damages. These results suggest that mitochondrial dysfunction might be one of the mechanisms leading to age-associated degeneration in SAMP mice at an early age and the platelets could serve as a biomarker for detection of mitochondrial function and age related disease.     

Stem cells in veterinary medicine--attempts at regenerating equine tendon after injury

Stem cells have evoked considerable excitement in the animal-owning public because of the promise that stem cell technology could deliver tissue regeneration for injuries for which natural repair mechanisms do not deliver functional recovery and for which current therapeutic strategies have minimal effectiveness. This review focuses on the current use of stem cells within veterinary medicine, whose practitioners have used mesenchymal stem cells (MSCs), recovered from either bone marrow or adipose tissue, in clinical cases primarily to treat strain-induced tendon injury in the horse. The background on why this treatment has been advocated, the data supporting its use and the current encouraging outcome from clinical use in horses treated with bone-marrow-derived cells are presented together with the future challenges of stem-cell therapy for the veterinary community.     

Formation of micronuclei in erythrocytes of the fathead minnow (Pimephales promelas) after acute treatment with mitomycin C or cyclophosphamide

Despite the widespread use of the fathead minnow in ecotoxicology, there have been relatively few studies on genotoxicity biomarkers in this small, warm-water fish species. Consequently, we investigated the effect of two known genotoxins, mitomycin C and cyclophosphamide, on micronucleus induction in spleen and peripheral blood erythrocytes of this species. Initially, 96-h experiments after intra-peritoneal (i.p.) injections of mitomycin C and cyclophosphamide were undertaken to determine the maximum tolerated dose (MTD). From these studies, MTDs of 10 and 400 mg/kg, respectively, were obtained: doses that were higher than those reported for other fish species. Next, an assessment of micronucleus induction at 1, 2, 4, 8 and 14 days after injection was undertaken for each compound at the MTD. Mitomycin C at 10 mg/kg significantly induced micronuclei in erythrocytes from the spleen, but not from the peripheral blood, at 8 and 14 days. In addition, the overall levels of micronuclei observed were lower than most previously published data from other fish species. In contrast to mitomycin C, treatment with 400 mg/kg cyclophosphamide failed to significantly induce micronuclei in erythrocytes from any of the tissues employed, in contrast to previous reports of significant induction in other species. The reasons for the apparent relative insensitivity of the fathead minnow to these clastogens, with respect to both MTDs and micronucleus induction, are not clear. The fathead minnow, however, has previously been described as relatively insensitive compared to other fish species with respect to selected carcinogens and cytochrome P450 inducers; the latter suggesting that the lack of a significant induction following cyclophosphamide exposure may be due to low metabolic activation in vivo. Consequently, further clarifying work is required to delineate the response shown, considering the extensive use of this species in ecotoxicology research and regulatory testing.     

Nutritional challenges during development induce sex-specific changes in glucose homeostasis in the adult sheep

The early-life environment has implications for risk of adult-onset diseases, such as glucose intolerance, insulin insensitivity, and obesity, effects that may occur with or without reduced birth weight. We determined the consequences of nutrient restriction in early gestation and early postnatal life and their interactions on postnatal growth, body composition, and glucose handling. Ewes received 100% (C, n = 39) or 50% nutritional requirements (U, n = 41) from 1 to 31 days gestation and 100% thereafter. Male and female offspring (singleton/twin) from C and U ewes were then fed either ad libitum (CC n = 22, UC n = 19) or to reduce body weight to 85% of target from 12 to 25 wk of age (CU n = 17, UU n = 22) and ad libitum thereafter. At 1.5 and 2.5 yr, glucose handling was determined by area under the curve (AUC) for glucose and insulin concentrations following intravenous glucose (0.5 g/kg body wt). Insulin sensitivity was determined at 2.5 yr following intravenous insulin (0.5 IU/kg). In females, postnatal undernutrition reduced (P < 0.05) glucose AUC at both ages, regardless of prenatal nutrition. Postnatal undernutrition did not affect insulin secretion in females but enhanced insulin-induced glucose disappearance in singletons. Poor early postnatal growth was associated with increased fat in females. In males, glucose tolerance was unaffected by undernutrition despite changes in insulin AUC dependent on age, treatment, and single/twin birth. Nutrition in early postnatal life has long-lasting, sex-specific effects on glucose handling in sheep, likely due, in females, to enhanced insulin sensitivity. Improved glucose utilization may aid weight recovery but have negative implications for glucose homeostasis and body composition over the longer term.     

Upregulation of PD-1 expression on circulating and intrahepatic hepatitis C virus-specific CD8+ T cells associated with reversible immune dysfunction

Infection with hepatitis C virus (HCV) is associated with persistence in the majority of individuals. We demonstrate here that the inhibitory molecule programmed death-1 (PD-1) is significantly upregulated on total and HCV-specific CD8(+) cytotoxic T lymphocytes (CTLs) in the peripheral blood and livers of patients with chronic infection compared to subjects with spontaneous HCV resolution, patients with nonviral liver disease, and normal controls. PD-1 expression on cytomegalovirus-specific CTLs also varies according to HCV status and is highest in patients with chronic infection. HCV-specific CTLs that are PD-1(high) express higher levels of the senescence marker CD57 than PD-1(low) CTLs, and CD57 expression is greater in chronic than in resolved infection. In vitro blockade of PD-1 by monoclonal antibodies specific to its ligands (PD-L1 and PD-L2) results in restoration of functional competence (proliferation and gamma interferon and interleukin-2 secretion) of HCV-specific CTLs, including those residing in the liver. This reversal of CTL exhaustion is evident even in individuals who lack HCV-specific CD4(+) T-cell help. Our data indicate that the PD-1/PD-L pathway is critical in persistent HCV infection in humans and represents a potential novel target for restoring function of exhausted HCV-specific CTLs.     

Creative or created: using anecdotes to investigate animal cognition

In non-human animals, creative behaviour occurs spontaneously only at low frequencies, so is typically missed by standardised observational methods. Experimental approaches have tended to rely overly on paradigms from child development or adult human cognition, which may be inappropriate for species that inhabit very different perceptual worlds and possess quite different motor capacities than humans. The analysis of anecdotes offers a solution to this impasse, provided certain conditions are met. To be reliable, anecdotes must be recorded immediately after observation, and only the records of scientists experienced with the species and the individuals concerned should be used. Even then, interpretation of a single record is always ambiguous, and analysis is feasible only when collation of multiple records shows that a behaviour pattern occurs repeatedly under similar circumstances. This approach has been used successfully to study a number of creative capacities of animals: the distribution, nature and neural correlates of deception across the primate order; the occurrence of teaching in animals; and the neural correlates of several aptitudes--in birds, foraging innovation, and in primates, innovation, social learning and tool-use. Drawing on these approaches, we describe the use of this method to investigate a new problem, the cognition of the African elephant, a species whose sheer size and evolutionary distance from humans renders the conventional methods of comparative psychology of little use. The aim is both to chart the creative cognitive capacities of this species, and to devise appropriate experimental methods to confirm and extend previous findings.     

Frequencies of single nucleotide polymorphisms in genes regulating inflammatory responses in a community-based population

Background

Researchers may embark on a genome-wide association study before fully investigating candidate regions which have been reported to produce evidence to suggest that they harbour susceptibility loci. If the genome wide study had not been carried out then results which demonstrated only modest statistical significance from candidate regions would be judged to be of interest and would stimulate further investigation. However if hundreds of thousands of markers are typed then inevitably very large numbers of such results will occur by chance and those from candidate regions may attract no special attention.

Results

An approach is proposed in which differential treatment is afforded to markers from candidate regions and from those that are routinely typed in the context of a genome wide scan. Different prior probabilities are assigned to the two types of marker. A likelihood ratio is derived from the reported p value for each marker, calculated as LR = e^{chiinv(1,p)/2}, and the posterior odds in favour of a true positive association are obtained. These odds can be used to rank the markers with a view to suggesting the regions in which further genotyping is indicated. We suggest that prior probabilities be specified such that a candidate marker significant at p = 0.01 and a routine marker significant at p = 0.00001 will yield similar values for the posterior odds. We show that this can be achieved by setting a value for prior probability of association to 0.1 for candidate markers and to 0.00018 for routine markers.

Conclusion

It is essential that formal procedures be adopted in order to avoid modestly positively results from candidate regions being swamped by the huge number of nominally significant results which will be obtained when very many markers are genotyped. Software to carry out the conversion from p values to posterior odds is available from http://www.mds.qmul.ac.uk/statgen/grpsoft.html.     

Anti-Sporothrix Antibody Detection in Domestic Cats as an Indicator of a Possible New Occurrence Area for Sporotrichosis in North Brazil

Mycopathologia - Feline sporotrichosis has emerged as an important public health issue in some countries, especially Brazil. Currently, zoonotic transmission of Sporothrix brasiliensis by domestic...     

Subgenomic promoter recognition by the norovirus RNA-dependent RNA polymerases

The replication enzyme of RNA viruses must preferentially recognize their RNAs in an environment that contains an abundance of cellular RNAs. The factors responsible for specific RNA recognition are not well understood, in part because viral RNA synthesis takes place within enzyme complexes associated with modified cellular membrane compartments. Recombinant RNA-dependent RNA polymerases (RdRps) from the human norovirus and the murine norovirus (MNV) were found to preferentially recognize RNA segments that contain the promoter and a short template sequence for subgenomic RNA synthesis. Both the promoter and template sequence contribute to stable RdRp binding, accurate initiation of the subgenomic RNAs and efficient RNA synthesis. Using a method that combines RNA crosslinking and mass spectrometry, residues near the template channel of the MNV RdRp were found to contact the hairpin RNA motif. Mutations in the hairpin contact site in the MNV RdRp reduced MNV replication and virus production in cells. This work demonstrates that the specific recognition of the norovirus subgenomic promoter is through binding by the viral RdRp.