Sizing individual dielectric nanoparticles with quantitative differential interference contrast microscopy.

We report a method to measure the size of single dielectric nanoparticles with high accuracy and precision using quantitative differential interference contrast (DIC) microscopy. Dielectric nanoparticles are detected optically by the conversion of the optical phase change into an intensity change using DIC. Phase images of individual nanoparticles were retrieved from DIC by Wiener filtering, and a quantitative methodology to extract nanoparticle sizes was developed. Using polystyrene beads of 100 nm radius as size standard, we show that the method determines this radius within a few nm accuracy. The smallest detectable polystyrene bead is limited by background and shot-noise, which depend on acquisition and analysis parameters, including the objective numerical aperture, the DIC phase offset, and the refractive index contrast between particles and their surrounding. Measurements on small beads of 15 nm nominal radius are shown, and a sensitivity limit potentially reaching down to 1.8 nm radius was inferred. As application example, individual nanodiamonds with nominal sizes below 50 nm were measured, and were found to have a nearly exponential size distribution with 28 nm mean value. Considering the importance of dielectric nanoparticles in many fields, from naturally occurring virions to polluting nanoplastics, the proposed method could offer a powerful quantitative tool for nanoparticle analysis, combining accuracy, sensitivity and high-throughput with widely available and easy-to-use DIC microscopy.

Empirical versus theoretical power and type I error (false-positive) rates estimated from real murine aging research data.

We assess the degree of phenotypic variation in a cohort of 24-month-old male C57BL/6 mice. Because murine studies often use small sample sizes, if the commonly relied upon assumption of a normal distribution of residuals is not met, it may inflate type I error rates. In this study, 3-20 mice are resampled from the empirical distributions of 376 mice to create plasmodes, an approach for computing type I error rates and power for commonly used statistical tests without assuming a normal distribution of residuals. While all of the phenotypic and metabolic variables studied show considerable variability, the number of animals required to achieve adequate power is markedly different depending on the statistical test being performed. Overall, this work provides an analysis with which researchers can make informed decisions about the sample size required to achieve statistical power from specific measurements without a priori assumptions of a theoretical distribution.

Maternally expressed gene 3 in metabolic programming.

Maternally Expressed Gene 3 (MEG3) is a long noncoding RNA (lncRNA) that coordinates a diverse array of cellular processes requiring epigenetic regulation of genes and interactions with key signaling proteins and by acting as a competitive endogenous (ce)RNA. Epigenetic modifications driven by in utero nutrition affect MEG3 expression and its role in the development of multiple metabolic disorders. This review examines how epigenetic modification of MEG3 expression can confer adaptedness to different metabolic environments. To this end, we discuss how nutritional status that leads to an increase of MEG3 expression can protect against cancer and metabolic dysfunctions, while interventions that promote MEG3 downregulation minimize the pleiotropic costs associated with its expression. Lastly, we identify research directions that would further shed light on the role of MEG3 in metabolic regulation and in functional imprinted gene networks. This article is part of a Special Issue entitled: ncRNA in control of gene expression edited by Kotb Abdelmohsen.

Demographics and husbandry of pet cats living in Sydney, Australia: results of cross-sectional survey of pet ownership.

Our aim was to collect baseline data on the age, gender, breed, reproductive status and husbandry (housing, diet, vaccination, veterinary attention) of pet cats living in Sydney. Accordingly, a cross-sectional survey of 2768 households was conducted using a postal questionnaire. The 2006 Sydney residential phone book was used as the sampling frame. Non-responders were re-mailed the questionnaire on two further occasions, 2 and 4 weeks after the first posting. Completed questionnaires were received from 884 households. No pets were kept by 387 (43.8%) respondents. Dogs and cats were owned by 295 (33.4%) and 198 (22.5%) of households, respectively, with 7.8% of households having both cat(s) and dog(s). Fish and birds were the next most popular pets. Of the 198 cat-owning households, 54.0% kept only cat(s), while 46.5% kept cats with other pets. The distribution of cat ownership across Sydney was non-uniform. Each cat-owning household kept 1.3 cats on average, with the majority keeping one (75.8% households) or two (18.7%). For the 260 cats, the mean age was 7.1 years, the median 6 years, with a range of 3 months to 22 years. There were significantly more female (143; 55%) than male cats (117; 45%). Only seven cats (2.7%) were sexually entire, and these were all < or =6 years. Crossbred cats outnumbered pedigree cats by a ratio of 3.3:1. The Burmese was the most common breed, followed by the Persian. The median age of pedigree cats (5.5 years) was significantly lower than for domestic crossbred cats (7.0 years). Most cats were housed both indoors and outdoors (72.6%), with 19.7% being restricted to indoors and/or 'pet park enclosures'. Pedigree cats were significantly more likely than crossbreds to be housed indoors. Most owners fed their cats a combination of commercial dry and canned food (38.1%), although fresh meat was popular also and either fed alone (1.6%) or in combination with dry food (14.4%), tinned food (1.6%) or canned and dry food (25.8%). A diet consisting of dry food alone was fed to cats in 13.4% of households. Ninety percent of cats had been vaccinated at least once, while 72.2% received a vaccination in the last 3 years. Older cats were less likely to have been vaccinated recently than younger cats. Only 5.8% of cats had never visited a veterinarian. For the 243 cats that had received veterinary attention, the average number of years since the last visit was 1.5.

Risk factors for emergence of exotic foot-and-mouth disease O/ME-SA/Ind-2001d on smallholder farms in the Greater Mekong Subregion.

Foot-and-mouth disease (FMD) is a significant endemic transboundary animal disease in Lao People's Democratic Republic (Lao PDR) and throughout the Greater Mekong Subregion (GMS). The disease has been shown to perpetuate the cycle of smallholder poverty through reduced animal production, plus limitations on market access for trading in livestock and their products. Despite significant national and multilateral efforts to control FMD over the past two decades, endemic FMD viruses (FMDVs) continue to circulate in Lao PDR. Further, the threat from new and emerging FMDVs is increasing as transboundary movements in the region intensify in response to increasing regional demand for meat. Although the economic impacts of FMD on smallholder farmers in Lao PDR are significant, studies investigating household-level risk factors for FMD are lacking. Following an outbreak of a novel FMDV (O/ME-SA/Ind2001d) in Lao PDR in 2015, a questionnaire and serological study were conducted in Naxaythong District to identify household-level risk factors associated with this outbreak, as well as endemic circulating viruses in the outbreak area. Data were analysed using a multivariable generalised estimating equation (GEE) model with a logit link function and associations were calculated as odds ratios (OR) with 95% confidence intervals (CI95%). After adjusting for other variables, the practice of quarantining new livestock for a minimum of two weeks prior to introduction to a herd was found to be a significant protective factor during the 2015 outbreak (OR 0.225, CI95% [0.06, 0.88], p-value 0.003). In addition, households owning one or more animals with titres to the non-structural proteins of FMDV, indicating prior infection, had 5.5 times the odds (CI95% [6.16, 49.11], p-value <0.001) of sharing communal grazing land with neighbouring villages. These findings indicate that implementing basic on-farm biosecurity and improved husbandry measures to minimise FMDV circulation at the household level are important and reinforce the need to enhance the education of smallholder farmers in infectious disease control.

Quantitative genetics of traits associated with hip dysplasia in a canine pedigree constructed by mating dysplastic Labrador Retrievers with unaffected Greyhounds.

OBJECTIVE: To determine the genetic influence on expression of traits associated with canine hip dysplasia. ANIMALS: 193 dogs from an experimental canine pedigree. PROCEDURE: An experimental canine pedigree was developed for linkage analysis of hip dysplasia by mating dysplastic Labrador Retrievers with nondysplastic Greyhounds. A statistical model was designed to test the effects of Labrador Retriever and Greyhound alleles on age at detection of femoral capital epiphyseal ossification, 8-month distraction index, and 8-month dorsolateral subluxation score. RESULTS: The additive effect was significant for age at detection of femoral capital epiphyseal ossification. Restricted maximum likelihood estimates (+/-SD) for this trait were 6.4+/-1.95, 10.2+/-2.0, 10.8+/-3.1, 11.4+/-2.1, and 13.6+/-4.6 days of age for Greyhounds, Greyhound backcross dogs, F1 dogs, Labrador Retriever backcross dogs, and Labrador Retrievers, respectively. The additive effect was also significant for the distraction index. Estimates for this trait were 0.21+/-0.07, 0.29+/-0.15, 0.44+/-0.12, 0.52+/-0.18, and 0.6+/-0.17 for the same groups, respectively. For the dorsolateral subluxation score, additive and dominance effects were significant. Estimates for this trait were 73.5+/-4.1, 71.3+/-6.5, 69.1+/-6.0, 50.6+/-12.9, and 48.4+/-7.7%, respectively, for the same groups. CONCLUSIONS: In this canine pedigree, traits associated with canine hip dysplasia are heritable. Phenotypic differences exist among founder dogs of each breed and their crosses. This pedigree should be useful for identification of quantitative trait loci underlying the dysplastic phenotype.

Power of a Labrador Retriever-Greyhound pedigree for linkage analysis of hip dysplasia and osteoarthritis.

OBJECTIVE: To estimate the number of dogs required to find linkage to heritable traits of hip dysplasia in dogs from an experimental pedigree. ANIMALS: 147 Labrador Retrievers, Greyhounds, and their crossbreed offspring. PROCEDURE: Labrador Retrievers with hip dysplasia were crossed with unaffected Greyhounds. Age at detection of femoral capital ossification, distraction index (DI), hip joint dorsolateral subluxation (DLS) score, and hip joint osteoarthritis (OA) were recorded. Power to find linkage of a single marker to a quantitative trait locus (QTL) controlling 100% of the variation in a dysplastic trait in the backcross dogs was determined. RESULTS: For the DI at the observed effect size, recombination fraction of 0.05, and heterozygosity of 0.75, 35 dogs in the backcross of the F1 to the Greyhound generation would yield linkage at a power of 0.8. For the DLS score, 35 dogs in the backcross to the Labrador Retriever generation would be required for linkage at the same power. For OSS, 45 dogs in the backcross to the founding Labrador Retrievers would yield linkage at the same power. Fewer dogs were projected to be necessary to find linkage to hip OA. Testing for linkage to the DLS at 4 loci simultaneously, each controlling 25% of the phenotypic variation, yielded an overall power of 0.7 CONCLUSIONS AND CLINICAL SIGNIFICANCE: Based on this conservative single-marker estimate, this pedigree has the requisite power to find microsatellites linked to susceptibility loci for hip dysplasia and hip OA by breeding a reasonable number of backcross dogs.

Patients with chronic pancreatitis are at increased risk for osteoporosis.

OBJECTIVES: Patients with chronic pancreatitis may be at an increased risk of low bone density because of malabsorption of vitamin D and calcium, poor diet, pain, alcoholism, and smoking. We investigated the rates of osteoporosis in patients with chronic pancreatitis compared to matched controls. METHODS: The study was cross sectional in design. Sixty-two patients (mean age, 47.9 years; 72.6% male) and 66 matched controls were recruited. Dual-energy x-ray absorptiometry, smoking, and socioeconomic data were recorded. RESULTS: Thirty-four percent of patients had osteoporosis compared to 10.2% of controls. T-scores at the right femoral neck were lower in patients than controls (P = 0.005). Patients in the highest smoking tertile had the poorest T-scores at the lumbar vertebrae and total hip. Patients in the youngest age tertile had the highest T-scores (P = 0.003), but there was no sex difference. CONCLUSIONS: Patient osteoporosis rates were triple that of controls, and almost 7 times what has been previously reported. Given the resource burden of osteoporosis, we suggest that routine bone density assessment is performed in patients with chronic pancreatitis.

A case of polyarteritis nodosa limited to the right calf muscles, fascia, and skin: a case report.

INTRODUCTION: Limited polyarteritis nodosa is a rare benign disease that usually responds well to systemic corticosteroid treatment. We report a case limited to calf muscles, fascia, and skin treated with local corticosteroid therapy directed to the affected areas by ultrasound guidance. CASE PRESENTATION: A 36-year-old Caucasian woman presented with a 10-month history of progressive right calf pain and swelling, which were unresponsive to treatment with non-steroidal anti-inflammatory drugs and physiotherapy. An examination revealed a swollen tender right calf with indurated overlying skin. Laboratory investigations showed an erythrocyte sedimentation rate of 24 mm/hour and a C-reactive protein of 15 mg/dl. Full blood count, renal profile, and creatinine kinase level were normal. A full autoantibody screen and hepatitis B and C serology results were negative. A chest X-ray was unremarkable. Magnetic resonance imaging of the right leg revealed increased signal intensity in T2-weighted images and this was suggestive of extensive inflammatory changes of the gastrocnemius muscle and, to a lesser extent, the soleus muscle. There were marked inflammatory changes throughout the gastrocnemius muscle and the subcutaneous tissue circumferentially around the right lower leg. A biopsy of affected skin, muscle, and fascia showed histopathological features consistent with polyarteritis nodosa, including small-vessel vasculitis with fibrinoid changes in the vessel wall and intense perivascular and focal mural chronic inflammatory changes. Our patient declined treatment with oral steroids. She received a course of ultrasound-guided injections of steroid (Depo-Medrone, methylprednisolone) in the involved muscle area and commenced maintenance azathioprine with a good response. CONCLUSIONS: Limited polyarteritis nodosa is rare and affects middle-aged individuals. In most cases, treatment with moderate- to high-dose corticosteroids gives symptomatic relief within one week. Resistant cases require treatment with cytotoxics or intravenous immunoglobulins. This case demonstrates response to local targeted steroid therapy as an alternative to systemic steroids.

The equine influenza epidemic in Australia: spatial and temporal descriptive analyses of a large propagating epidemic.

Australia experienced a large outbreak of equine influenza in August 2007. Nearly 10000 premises were infected during the epidemic. We used spatial and temporal analytical techniques to describe the epidemic, to quantify important descriptors of the epidemic, and to generate hypotheses about how the epidemic progressed and which control tools assisted in eradication. Spatio-temporal epidemic curves revealed three phases in the epidemic: dispersal, local spread and disease fade out. Spatial dispersal of infection rapidly declined immediately after national movement restrictions were introduced. The epidemic peak had passed before emergency vaccination could have induced substantial immunity in the equine population. Thirty seven clusters of epidemiologically linked premises were delineated using an interpolated surface of date of onset of clinical signs, geographic data and location of infected premises. These clusters were analysed individually to parameterise key epidemic measures: cumulative incidence, incidence rate, effective reproduction rate, nearest neighbour spread distances, epidemic length and the number of infected premises. These measures were summarised by landscape (rural versus peri-urban location) and standardised by disease management zone. Compared to rural areas, peri-urban areas appeared to have a higher density of equine premises (4.66 premises km(-2) versus 0.80 premises km(-2)), longer epidemics (95 days versus 87 days), more infected premises (393 versus 339) and a shorter spread distance (1.27 km versus 2.38 km). However, effective reproduction rates (2.04 versus 1.99), cumulative incidence (27.4 versus 26.9) and incidence rates (1.36 versus 1.54) were similar. The relative impact of vaccination and national movement restrictions in controlling this epidemic needs further investigation.

Identifying areas of Australia at risk of H5N1 avian influenza infection from exposure to migratory birds: a spatial analysis.

Since 2003, highly pathogenic avian influenza (HPAI) due to H5N1 virus has been reported from both domestic poultry and wild birds in 60 countries resulting in the direct death or slaughter of over 250,000,000 birds. The potential exists for HPAI to spread to Australia via migratory shorebirds returning from Asia with the most likely pathway of introduction into commercial poultry flocks involving the transfer of HPAI from migrating shorebirds to native waterfowl species that subsequently interact with poultry on low security poultry farms. Surveillance programmes provide an important early-warning for Australia's estimated 2,000 commercial poultry farms but, to be efficient, they should be risk-based and target resources at those areas and sectors of the industry at higher risk of exposure. This study compared the distributions of migratory shorebirds and native waterfowl to identify six regions where the likelihood of exotic HPAI incursion and establishment in native waterfowl is highest. Analysis of bird banding records showed that native waterfowl did not move further than 10 km during the spring breeding season when migratory shorebirds arrived in Australia. Therefore, poultry farms within 10 km of significant shorebird habitat in these six regions of highest comparative risk were identified. The final analysis showed that the estimated risk to Australia is low with only two poultry farms, one at Broome and one at Carnarvon, located in the regions of highest risk.

Identifying areas of Australia at risk for H5N1 avian influenza infection from exposure to nomadic waterfowl moving throughout the Australo-Papuan region.

Since 2003, highly pathogenic avian influenza (HPAI) due to the H5N1 virus has been reported from both domestic poultry and wild birds in over 60 countries and this has resulted in the direct death or slaughter of over 250 million birds. The potential for HPAI to be introduced to Australian commercial poultry via migratory shorebirds returning from Asia has previously been assessed as a low risk. However, introduction of HPAI from areas to the immediate north of Australia via nomadic waterfowl that range throughout the Australo-Papuan region provides a second potential pathway of entry. Surveillance programmes provide an important early warning for Australia's estimated 2,000 commercial poultry farms but to be efficient they should be risk-based and target resources at those areas and sectors of the industry at higher risk of exposure. In order to address this need, this study compared the distribution and movement patterns of native waterfowl to identify regions where the likelihood of HPAI incursion and establishment was highest. Analysis of bird banding records provided information on the maximum distances moved and dispersal patterns of the species of waterfowl of interest. Introduction via Cape York was found to be most likely and all poultry farms in Queensland were found to be within range of waterfowl that can shed H5N1 virus for up to 17 days. The final analysis showed that the area at greatest risk of HPAI introduction is the Atherton tableland near Cairns.

Is ultrasound really helpful in the detection of rib fractures?

OBJECTIVE: To determine the usefulness of ultrasound in the detection of rib fractures. PATIENTS AND METHODS: A prospective study was performed over a 3-month period. Patients presenting with a high clinical suspicion of rib fracture(s) to the Accident and Emergency Department were referred for radiological work-up with a PA chest radiograph, an oblique rib view and a chest ultrasound. Associated lesions, e.g. pleural effusion, splenic laceration and pneumothorax were recorded. RESULTS: Fourteen patients were radiologically assessed. The mean patient age was 31 years (range 16-55 years) and the M:F ratio 3.7:1 (11 men and 3 women). Ten patients displayed a total of 15 broken ribs. Chest radiography detected 11, oblique rib views 13 and ultrasound 14 broken ribs. Ultrasound findings included discontinuity of cortical alignment in 12 fractures, an acoustic linear edge shadow in nine and a reverberation artifact in six. Concordance with plain film findings, and especially oblique rib views, was good, though better when the rib fractures fragments were markedly displaced. One splenic laceration was detected with an associated small pleural effusion. There were no pneumothoraces. The average time of ultrasound examination was 13 min. CONCLUSION: Ultrasound does not significantly increase the detection rate of rib fractures, may be uncomfortable for the patient and is too time-consuming to justify its routine use to detect rib fractures.