Appendicular skeletal muscle mass assessment in dogs: a scoping literature review.

BACKGROUND: Monitoring changes in appendicular skeletal muscle mass is frequently used as a surrogate marker for limb function. The primary objective of this study was to review scientific information related to the assessment of appendicular skeletal muscle mass in dogs. The secondary objective was to develop practical recommendations for serial evaluation of muscle mass. METHODS: A scoping review was conducted with a systematic search of PubMed, Web of Science, CAB abstract, and Cochrane from inception to June 2021. The following modalities were included in the search: limb circumference, diagnostic ultrasound, computed tomography, magnetic resonance imaging, and dual-energy x-ray absorptiometry. RESULTS: A total of 62 articles that measured appendicular skeletal muscle mass in dogs were identified. Limb circumference (55 articles) was the most commonly used modality. Its reliability was investigated in five studies. Several factors, including measuring tape type, body position, joint angles, and the presence of hair coat, were reported as variables that can affect measurements. Diagnostic ultrasound (five articles) was validated in three articles, but there is scarce information about observer reliability and variables affecting the measurement. Computed tomography (four articles) and magnetic resonance imaging (one article) have been used to validate other modalities at a single time point rather than as a clinical tool for serial muscle mass monitoring. Dual-energy x-ray absorptiometry (two articles) has been used to quantify specific skeletal muscle mass but was mainly used to evaluate body composition in dogs. CONCLUSION: Limb circumference and ultrasound are likely the main modalities that will continue to be used for serial muscle mass measurement in the clinical setting unless a new technology is developed. The reliability of limb circumference is questionable. Several key factors, including measuring tape type, body position, joint angles, and coat clipping, need to be controlled to improve the reliability of limb circumference measurements. Ultrasound may provide a reasonable alternative, but further studies are required to evaluate the reliability of this modality and identify factors that influence ultrasound measurements.

[Endovascular thrombectomy in patients with intracranial large artery occlusion and atrial fibrillation].

Objective: To investigate the safety and efficacy of mechanical thrombectomy in patients with atrial fibrillation complicated with acute intracranial arterial occlusion. Methods: Fifty-eight patients with atrial fibrillation complicated with acute intracranial arterial occlusion in the intervention group of East (Endovascular Therapy for Acute ischemic Stroke Trial) were analyzed. According to the TOAST (Trial of Org 10 172 in Acute Stroke Treatment) classification, patients were divided into ICAS (Intracranial Atherosclerotic Stenosis) group and cardiogenic embolism group. Clinical characteristics, treatment methods and clinical prognosis were compared between ICAS group and cardiogenic embolism group. Results: A total of 58 patients with atrial fibrillation complicated with acute intracranial arterial occlusion were included in this study, including 46 patients in the cardiogenic embolism group (79%) and 12 patients in the ICAS group (21%). The pre-hospital transport time in ICAS group was longer than that in cardiogenic embolism group (P<0.05).Patency rate in patients with atrial fibrillation complicated with acute intracranial arterial occlusion was 98.3% (57/58), The rate of patients with the 90-day function independent (mRS 0-2) was 51.7% (30/58). There were no statistically significant differences in functional independence, mortality rate, ICH and sICH at 90 days between the cardiogenic embolism group and the ICAS group. Conclusions: Mechanical thrombectomy is an effective method to treat patients with atrial fibrillation complicated with acute intracranial arterial occlusion.

Evaluation of antibody response to an adjuvanted hapten-protein vaccine as a potential inhibitor of sexual maturation for farmed Atlantic salmon.

An experimental contraceptive vaccine was evaluated in Atlantic salmon (Salmo salar). A peptide derived from the beta subunit of luteinizing hormone (LH) was conjugated to two different carrier proteins, bovine serum albumin (BSA) and keyhole limpet hemocyanin (KLH), and formulated with one of four immunostimulants in a water-in-oil emulsion. Specific antibody responses to the peptide and each carrier protein were evaluated. While the antibody response to KLH was stronger than the response to BSA, both carrier proteins stimulated comparable antibody responses to the LH peptide. The immunostimulant proved to be more important for enhancing the LH peptide antibody response than the carrier protein selection; vaccines containing a combination of Aeromonas salmonicida and Vibrio anguillarum stimulated significantly greater LH peptide antibody production than any of the other three immunostimulants evaluated at 12 weeks post-vaccination. This study provides proof-of-concept for specific antibody production against a hapten-carrier protein antigen in Atlantic salmon and reinforces the importance of vaccine immunostimulant selection.

Relative contributions of testosterone deficiency and metabolism syndrome at the risk of reduced quality of life: A cross-sectional study among Chinese mid-aged and elderly men.

Testosterone deficiency and metabolism syndrome (MetS) are universal among ageing males, and they have been suggested responsible for poorer quality of life (QoL). We aimed to evaluate the relative contributions of reproductive hormones and components of MetS at the risk of reduced QoL among Chinese mid-aged and elderly men. A cross-sectional study recruited 2,364 males aged 40-79 years, and 2,165 was included for analysis eventually. The Chinese version of ageing male symptoms scale, 36-item Short Form and Beck Depression Inventory were applied to assess QoL. Bivariate correlation analysis and multiple linear regression analysis were used to assess the relative contributions of reproductive hormones and components of MetS at the risk of reduced QoL. Testosterone deficiency and MetS contributed to poorer QoL, of which higher fasting blood glucose made the primary contribution, lower total testosterone mainly contributed to poorer physical functioning.

PD-1 or CTLA-4 blockade promotes CD86-driven Treg responses upon radiotherapy of lymphocyte-depleted cancer in mice.

Radiotherapy (RT) is considered immunogenic, but clinical data demonstrating RT-induced T cell priming are scarce. Here, we show in a mouse tumor model representative of human lymphocyte-depleted cancer that RT enhanced spontaneous priming of thymus-derived (FOXP3+Helios+) Tregs by the tumor. These Tregs acquired an effector phenotype, populated the tumor, and impeded tumor control by a simultaneous, RT-induced CD8+ cytotoxic T cell (CTL) response. Combination of RT with CTLA-4 or PD-1 blockade, which enables CD28 costimulation, further increased this Treg response and failed to improve tumor control. We discovered that upon RT, the CD28 ligands CD86 and CD80 differentially affected the Treg response. CD86, but not CD80, blockade prevented the effector Treg response, enriched the tumor-draining lymph node migratory conventional DCs that were positive for PD-L1 and CD80 (PD-L1+CD80+), and promoted CTL priming. Blockade of CD86 alone or in combination with PD-1 enhanced intratumoral CTL accumulation, and the combination significantly increased RT-induced tumor regression and OS. We advise that combining RT with PD-1 and/or CTLA-4 blockade may be counterproductive in lymphocyte-depleted cancers, since these interventions drive Treg responses in this context. However, combining RT with CD86 blockade may promote the control of such tumors by enabling a CTL response.

Virological and immunological correlates of HIV posttreatment control after temporal antiretroviral therapy during acute HIV infection.

OBJECTIVE: People with HIV rarely control viral replication after cessation of antiretroviral therapy (ART). We present a person with HIV with extraordinary posttreatment control (PTC) for over 23 years after temporary ART during acute HIV infection (AHI) leading to a new insight in factors contributing to PTC. DESIGN/METHODS: Viral reservoir was determined by HIV qPCR, Intact Proviral DNA Assay, and quantitative viral outgrowth assay. Viral replication kinetics were determined in autologous and donor PBMC. IgG levels directed against HIV envelope and neutralizing antibodies were measured. Immune phenotyping of T cells and HIV-specific T-cell responses were analyzed by flow cytometry. RESULTS: The case presented with AHI and a plasma viral load of 2.7 million copies/ml. ART was initiated 2 weeks after diagnosis and interrupted after 26 months. Replicating virus was isolated shortly after start ART. At 18 years after treatment interruption, HIV-DNA in CD4 + T cells and low levels of HIV-RNA in plasma (<5 copies/ml) were detectable. Stable HIV envelope glycoprotein-directed IgG was present during follow-up, but lacked neutralizing activity. Strong antiviral CD8 + T-cell responses, in particular targeting HIV-gag, were detected during 25 years follow-up. Moreover, we found a P255A mutation in an HLA-B∗44 : 02 restricted gag-epitope, which was associated with decreased replication. CONCLUSION: We describe an exceptional case of PTC, which is likely associated with sustained potent gag-specific CD8 + T-cell responses in combination with a replication attenuating escape mutation in gag. Understanding the initiation and preservation of the HIV-specific T-cell responses could guide the development of strategies to induce HIV control.

Checking into China's cow hotels: have policies following the milk scandal changed the structure of the dairy sector?

China's milk scandal is well known for causing the nation's largest food safety crisis and for its effect on thousands of children. Less, however, is known about the effect on the other victim: China's small dairy farmers. Although small backyard producers were not the ones that added melamine to the milk supply, the incomes of dairy farmers fell sharply after the crisis. In response, one of the actions taken by the government was to encourage small dairy producers to check into production complexes that were supposed to supply services, new technologies, and provide for easy/bulk procurement of the milk produced by the cows of the farmers. Because both farmers and their cows were living (and working) away from home, in the rest of the paper we call these complexes cow hotels. In this paper we examine the dynamics of China's dairy production structure before and after the milk scandal. In particular, we seek to gain a better understanding about how China's policies have been successful in encouraging farmers to move from the backyard into cow hotels. We also seek to find if larger or smaller farmers respond differently to these policy measures. Using data from a sample of farmers from dairy-producing villages in Greater Beijing, our empirical analysis finds that 1 yr after the milk scandal, the dairy production structure changed substantially. Approximately one quarter (26%) of the sample checked into cow hotels after the milk scandal, increasing from 2% before the crisis. Our results also demonstrate that the increase in cow hotel production can largely be attributed to China's dairy policies. Finally, our results suggest that the effects of government policy differ across farm sizes; China's dairy policies are more likely to persuade larger farms to join cow hotels. Apparently, larger farms benefit more when they join cow hotels. Overall, these results suggest that during the first year after the crisis, the government policies were effective in moving some of the backyard farmers into cow hotels (although 60% farmers remained backyard producing).

Transcutaneous Detection of Intramural Microchips for Tracking the Migration of the Equine Large Colon: A Pilot Study.

Colic remains the number one cause of mortality in horses, and large colon displacement including colonic volvulus is one of the leading causes for equine hospitalization and surgery. Currently, there is not an adequate model to study the pathophysiology of this condition. The objective of this proof-of-concept study was to determine if subserosal implantation of bioinert microchips in the large intestine would be detectable by a RFID (radio-frequency identification) receiver when the implanted microchips were adjacent to the body wall, thus identifying the location of the colon within the abdomen. A horse with no history of gastrointestinal disease underwent a ventral midline celiotomy to implant twelve bioinert microchips into the subserosa at predetermined locations within the large colon and cecum. A RFID scanner was used to monitor the location of the colon via transcutaneous identification 1-3 times daily for a one-month period. Following humane euthanasia, a postmortem examination of the horse was performed to assess microchip implantation sites for migration and histologic assessment. Eleven out of the 12 implanted microchips were successfully identified transcutaneously at occurrences as high as 100%. Odds ratios were calculated for the likelihood of identifying each chip in a location different from its most common location. Microchips implanted into the subserosa of the equine large colon can be used as a means of identifying the approximate location of the equine large colon via transcutaneous identification with an RFID scanner.

Influence of Chronic Lameness on Thoracolumbar Musculus Multifidus Structure in the Horse.

The clinical relationship between equine limb lameness and secondary back dysfunction is largely unknown. Proper function of the spine is critical to maintain the integrity of the kinetic chain and attenuate forces from the appendicular skeleton. The musculus multifidus (m. multifidus) is the primary muscle providing spinal intersegmental stabilization and a functional relationship between m. multifidus hypertrophy and equine postural stability has been established. The relationship between equine thoracolumbar m. multifidus cross-sectional area (CSA) and limb lameness is unknown. The objective was to evaluate ultrasonographic changes in thoracolumbar m. multifidus CSA in horses with chronic single limb lameness, compared with sound horses. We hypothesized that the CSA of m. multifidus, ipsilateral to the lame limb would be smaller than the contralateral side, and within the sound group there would be no difference between sides. Thirty-six horses were enrolled, with twelve horses per group: sound, forelimb lame, and hindlimb lame. M. multifidus CSA was measured ultrasonographically at multiple spinal levels and compared between groups, spinal levels, and sides. M. multifidus CSA at the spinal level T18 was significantly larger than at all other measured levels, regardless of group (P ≤ .05). CSA at all levels was significantly larger in sound horses than the forelimb lame group, regardless of side (P = .002). This is the first study to evaluate the impact of chronic lameness on the axial skeleton and showed a decrease in m. multifidus CSA with forelimb lameness. These results support that axial skeletal adaptation occurs in response to naturally occurring chronic lameness.

Socio-ecological Factors of Zoonotic Diseases Exposure in Colorado Dairy Workers.

Objectives: Zoonotic pathogens on dairy farms are a known risk for people who work and live there. Exposure and/or transmission of Salmonella serovars, E. coli (O157; H7), Campylobacter jejuni, and Cryptosporidium parvum have been documented to occur in the dairy farm environment. Social ecological factors have been identified as determinants of preventive behaviors of people at risk of infectious diseases.Methods: This study described the effect of socio-ecological factors on selected zoonotic bacterial and protozoal diseases in 42 workers of two dairy farms.Results: Occupational exposure to Salmonella ser. Dublin, E. coli, and Campylobacter spp. was confirmed. Self-efficacy and negative workplace perceptions were risk factors for Salmonella Dublin exposure (OR = 1.43[95% CI 1.11-2.22] & 1.22 [95% CI 1.02-1.53] respectively,). Additionally, safety knowledge and risk perceptions were protective factors of exposure (OR = 0.90 [95% CI 0.79-1.00]). Positive perceptions of supervisors and coworkers was a protective factor of Campylobacter exposure (OR = 0.89 [95% CI 0.79-0.98]).Conclusion: Results indicated that the presence of a supporting organizational environment, good communication with supervisors and coworkers, and training on prevention of zoonotic diseases would potentially reduce occupational exposures to zoonotic diseases on these farms.

Antimicrobial drug resistance profile of isolated bacteria in dogs and cats with urologic problems at Chiang Mai University Veterinary Teaching Hospital, Thailand (2012-2016).

The present study aimed to estimate the proportion of bacterial urinary tract infection (UTI) in dogs and cats, assess risks associated with bacterial UTI, and to determine bacterial isolates' antimicrobial susceptibility and resistance pattern from the urinary tract of dogs and cats with urologic problems. The medical records from animals visiting Chiang Mai University Small Animal Veterinary Teaching Hospital between January 2012 and December 2016 were reviewed. In total, 203 dogs and 49 cats with urinary tract diseases that had samples submitted for bacterial culture were identified;198 and 24 bacterial isolates were recovered from dogs' and cats' submitted samples, respectively. At least one episode of bacterial UTI was detected in 75.4% (95% CI: 69.4-81.3) of dogs and in 40.8% (95% CI: 26.6-55.1) of cats with UTI and submitted urine cultures. Of 242 submitted urinary samples from dogs and 60 urinary samples from cats, bacteria were identified in 74.0% (95% CI: 68.4-79.5) and 38.3% (95% CI: 26.0-50.6), respectively. The most common pathogen of bacteria positive cultured from dogs was Staphylococcus spp. (30.3%), followed by Escherichia coli (16.7%), and Proteus spp. (13.6%). For cats, the most common pathogen was Pseudomonas spp. (25.0%), followed by E. coli (20.8%) and Proteus spp. (16.7%). Staphylococcus spp. isolates from dogs and Proteus spp. isolates from cats were highly susceptible to Amoxicillin/clavulanic acid (AMC) at 88% and 75%, respectively. Of all isolated bacteria, 67.1% of the bacteria from dogs and 83.3% from cats were multidrug-resistant (MDR). The proportion of MDR-bacterial urinary tract infections in dogs and cats with urologic problems in this study was high. This observation raises concerns regarding the potential of zoonotic transmission of MDR-bacteria from these companion animals. The results suggested that AMC remains a good empirical drug for treating UTIs in dogs in this region.

[Application of intestinal stent in prevention of anastomotic leakage after rectal cancer operation].

Objective: To observe preventive effect of intestinal stent against anastomotic leakage after rectal cancer operation. Methods: A retrospective cohort study was carried out. Clinical data of 107 patients with low rectal cancer undergoing laparoscopic radical resection from January 2015 to August 2019 were retrospectively analyzed. Intestinal stent was placed intraoperatively in 48 cases and was not placed in 59 cases. Postoperative Wexner score for anal function and incidence of anastomotic leakage were compared between patients with and without intstinal stent. Results: There was no significant differences in age, distance between tumor and the anal verge, operative time and postoperative Wexner score for anal function between the two groups (all P>0.05). After a month of follow-up, the incidence of anastomotic leakage was 16.9% (10/59) in the non-stent group, while no anastomotic leakage was found in the stent group (P=0.002). Conclusion: Placement of intestinal stent can effectively prevent anastomotic leakage after low rectal cancer surgery.

Seasonal distributions and other risk factors for Giardia duodenalis and Cryptosporidium spp. infections in dogs and cats in Chiang Mai, Thailand.

The objectives of this study were to explore risk factors associated with Giardia and Cryptosporidium infections in dogs and cats in Chiang Mai, Thailand, to describe the seasonal distributions of Giardia and Cryptosporidium prevalence, and to determine the potential for zoonotic transmission through genetic characterization of isolates. Fecal samples from 301 dogs and 66 cats were collected between August 2009 and February 2010. The presence of Giardia cysts and Cryptosporidium oocysts was determined using zinc sulfate centrifugal flotation and immunofluorescent assay (IFA). Genotype/species were determined by DNA sequence analyses of PCR products from Giardia glutamate dehydrogenase (gdh), beta-giardin (bg), and triosephosphateisomerase (tpi) and Cryptosporidium heat shock protein 70KDa (hsp70) and small subunit-rRNA (SSU-rRNA) genes. Information related to specific risk factors was collected from owners of each animal using a questionnaire. The risk factor data were analyzed for associations with Giardia and Cryptosporidium infections using logistic regression. The overall estimated prevalence of Giardia and Cryptosporidium in dogs was 25.2% and 7.6%, respectively and in cats, 27.3% and 12.1%, respectively. The estimated prevalence of Giardia infection in dogs in the rainy season (31.7%) was significantly higher than in the drier, winter season (17.2%) (p < 0.01). The estimated prevalence of Cryptosporidium infection in dogs and of Giardia and Cryptosporidium infections in cats was not associated with season (p > 0.05). Multivariable analysis indicated that Giardia cysts were more likely to be detected in fecal samples of dogs that resided in high-density environments, drank untreated water, were shedding Cryptosporidium oocysts, were having acute diarrhea or a history of chronic diarrhea, and were collected in the rainy season. All 19 Giardia PCR positive samples typed as G. duodenalis canine adapted genotypes (assemblages C or D). In cats, of six Giardia PCR positive samples, five typed as dog assemblages and one typed as assemblage AI. Of ten dogs with Cryptosporidium PCR positive samples, eight typed as C. canis, one as C. parvum (a zoonotic species) and one had both C. canis and C. parvum. Of three Cryptosporidium PCR positive samples in cats, one typed as C. felis and two typed as C. parvum. The presence of zoonotic G. duodenalis assemblage AI in a cat, and C. parvum in feces of dogs and cats suggests a potential role for a reservoir for zoonotic transmission. Whether or not these presences were from exposure to other animal or human hosts or environment are needed to be confirmed.

Challenges to the Application of Spatially Explicit Stochastic Simulation Models for Foot-and-Mouth Disease Control in Endemic Settings: A Systematic Review.

Simulation modeling has become common for estimating the spread of highly contagious animal diseases. Several models have been developed to mimic the spread of foot-and-mouth disease (FMD) in specific regions or countries, conduct risk assessment, analyze outbreaks using historical data or hypothetical scenarios, assist in policy decisions during epidemics, formulate preparedness plans, and evaluate economic impacts. Majority of the available FMD simulation models were designed for and applied in disease-free countries, while there has been limited use of such models in FMD endemic countries. This paper's objective was to report the findings from a study conducted to review the existing published original research literature on spatially explicit stochastic simulation (SESS) models of FMD spread, focusing on assessing these models for their potential use in endemic settings. The goal was to identify the specific components of endemic FMD needed to adapt these SESS models for their potential application in FMD endemic settings. This systematic review followed the PRISMA guidelines, and three databases were searched, which resulted in 1176 citations. Eighty citations finally met the inclusion criteria and were included in the qualitative synthesis, identifying nine unique SESS models. These SESS models were assessed for their potential application in endemic settings. The assessed SESS models can be adapted for use in FMD endemic countries by modifying the underlying code to include multiple cocirculating serotypes, routine prophylactic vaccination (RPV), and livestock population dynamics to more realistically mimic the endemic characteristics of FMD. The application of SESS models in endemic settings will help evaluate strategies for FMD control, which will improve livestock health, provide economic gains for producers, help alleviate poverty and hunger, and will complement efforts to achieve the Sustainable Development Goals.

Increased vascular permeability precedes cellular inflammation as asthma control deteriorates.

BACKGROUND: Airway microcirculation is abnormal in asthma but the role of vascular changes in asthma deteriorations remains poorly defined. We prospectively assessed the vascular changes accompanying worsening of asthma control by using an inhaled corticosteroid (ICS) dose-reduction model. OBJECTIVES: To evaluate airway vascularity, vascular permeability and expression of vascular endothelial growth factor (VEGF) in early asthma deterioration induced by ICS back-titration. METHODS: Twenty mild-to-moderate persistent symptomatic asthmatics on low-to-moderate ICS were recruited and treated with 4 weeks of high-dose fluticasone propionate (1000 microg/day) to achieve symptom control. This was followed by dose reduction to half of the pre-study doses for 4-8 weeks until the symptoms began to return. Endobronchial biopsy and bronchoalveolar lavage (BAL) samples were obtained after both treatment periods. RESULTS: Vascularity as measured by the number and size of blood vessels, as well as VEGF expression did not change following ICS reduction. Even on high-dose ICS, perivascular albumin staining and BAL microalbumin levels in asthmatic subjects, as markers of permeability, were elevated when compared with normal subjects and both further increased significantly after ICS reduction. There was a significant association between changes in vascular leakiness and clinical deterioration. Increases in airway albumin correlated with previously reported increases in airway wall infiltration with T lymphocytes. CONCLUSIONS: Our results suggest that airway vascular leakage is a major pathophysiologic feature of early asthma deterioration, occurring before recrudescence of cellular inflammation.

Evaluation of immunohistochemical detection of prion protein in rectoanal mucosa-associated lymphoid tissue for diagnosis of scrapie in sheep.

OBJECTIVE: To determine the suitability and estimate the sensitivity of an immunohistochemical (IHC) test for disease-associated prion protein (PrP(Sc)) in biopsy specimens of rectoanal mucosa-associated lymphoid tissue (RAMALT) for diagnosis of scrapie in sheep. ANIMALS: 762 sheep at high risk for having scrapie and indemnified by the National Scrapie Eradication Program. PROCEDURES: The IHC test for PrP(Sc) was applied to 2 RAMALT and 2 third-eyelid biopsy specimens and a postmortem RAMALT specimen from each sheep. Results were compared with those of a reference test in which results for tissues from obex and retropharyngeal lymph nodes, tonsil, or both were considered in parallel. RESULTS: The reference test identified 139 sheep as having scrapie. Biopsy-related complications occurred in 3 sheep. Sensitivity of the IHC test in RAMALT ranged from 85.3% to 89.4%, depending on the anatomic location from which RAMALT was obtained. Results for the test applied to 1 RAMALT specimen were similar to results interpreted in parallel for 2 third-eyelid specimens (sensitivity, 87.0%). The proportion of inconclusive test results attributable to insufficient lymphoid follicles in biopsy specimens was lower when considering results for 2 RAMALT specimens in parallel (10.1%) than when considering results for 2 third-eyelid specimens in parallel (23.7%). Specimens of RAMALT that were inappropriately collected from an area caudal to the rectoanal interface yielded a high proportion of inconclusive results (33.3% to 50.0%). CONCLUSIONS AND CLINICAL RELEVANCE: The IHC test for PrP(Sc) in RAMALT was an effective means of detecting subclinical scrapie in live, high-risk sheep.

First principle study on the predicted phase transition of MN (M = Zr, La and Th).

First principle (FP) calculations were performed to systematically study the structural properties of ZrN, LaN and ThN with GGA correction. The ground state properties, wave velocities and Debye temperature of B1, P63/mmc, Pnma and B2 phase in ZrN, LaN and ThN were investigated and agree well with other theoretical and experimental results. More importantly, some novel phases are predicted in these materials, i.e. with the increasing pressure the phase transition sequence in ZrN and ThN is found to be B1 → P63/mmc → B2 phase, while in LaN, the sequence of B1 → Pnma → B2 is observed. Furthermore, our calculated elastic properties also confirm the prediction of phase transition under high pressure. These phase transitions arise from the optical phonon softening of B1 at around X, M and G points of Brillouin zone and P63/mmc (or Pnma) structure at around G, and H-K points.