Preclinical safety and efficacy of andexanet alfa in animal models

Essentials There is currently no approved reversal agent for factor Xa (FXa) inhibitors Andexanet alfa has been developed to reverse the anticoagulant effects of FXa inhibitors Andexanet reduced blood loss and anticoagulation markers in rivaroxaban-anticoagulated rabbits Andexanet was well tolerated in monkeys and rats, with no evidence of prothrombotic activity SUMMARY: Background Andexanet alfa is a recombinant modified form of factor Xa (FXa), designed to bind to and reverse the anticoagulant activity of FXa inhibitors. Objectives To evaluate the ability of andexanet to reverse the anticoagulant activity of rivaroxaban, and assess its pharmacokinetics (PK) and toxicity in animal models. Methods The effects of andexanet on blood loss, anti-FXa activity, rivaroxaban unbound plasma concentrations and other coagulation parameters were assessed in a rabbit liver laceration 'treatment' model. Andexanet was administered 10 min after blood loss was initiated. The toxicity of repeated administration of andexanet (up to 60 mg kg-1 day-1 ) was assessed in cynomolgus monkeys. PK parameters were evaluated in rats and monkeys. Results Excess blood loss due to anticoagulation with rivaroxaban was significantly decreased by a single intravenous bolus administration of andexanet at 35 and 75 mg per rabbit, by 75% and 63%, respectively. This correlated with dose-dependent decreases in the unbound fraction of rivaroxaban and anti-FXa activity. Co-administration of rivaroxaban had no significant impact on the PK parameters of andexanet. Andexanet (up to 60 mg kg-1 day-1 ) was well tolerated in monkeys, with no accumulation of andexanet or rivaroxaban. There was a single occurrence of anaphylaxis, which resolved after treatment with diphenhydramine and epinephrine. There was no histological evidence of prothrombotic activity with high-dose andexanet compared with vehicle control, as measured by clot and fibrin deposition in all major organs. Conclusions These data suggest that andexanet is a promising therapy for the reversal of FXa inhibitor-induced anticoagulation, supporting clinical studies in humans.

Polymer-Encapsulated PC12 Cells: Long-Term Survival and Associated Reduction in Lesion-Induced Rotational Behavior

Intrastriatal implantation of a dopaminergic cell line surrounded by a permeable, thermoplastic membrane was investigated as a method of long-term dopamine (DA) delivery within the central nervous system (CNS). An increase in DA release from PC12 cell-loaded capsules maintained in vitro was associated with an increase in mitotic activity of the encapsulated cell line. A significant reduction in apomorphine-induced rotational behavior was observed after PC12 cell-containing capsules were implanted into unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats, which was sustained for 24 wk. Four wk after implantation, micro-dialysis studies revealed the presence of DA near PC12 cell-containing capsules, which was comparable to extracellular striatal levels of unlesioned controls. Extracellular striatal DA was undetectable by microdialysis in lesioned animals near empty polymer capsules. Histological analysis after 24 wk in vivo demonstrated that encapsulated PC12 cells survived, continued to express tyrosine hydroxylase, and that encapsulation prevented tumorigenesis. The data suggested that the release of a diffusible substance, most likely DA, from an implant is sufficient to exert a long-term functional influence upon 6-OHDA unilaterally lesioned rats and that capsules containing DA-secreting cells may be an effective method of long-term DA delivery in the CNS.

Breast magnetic resonance imaging: are those who need it getting it?

BACKGROUND

Indications for breast magnetic resonance imaging (mri), a very sensitive but less-specific tool for breast investigation, remain controversial, and accessibility is limited. The purposes of our study were to determine the proportion of breast mri exams performed for various clinical indications, to assess the wait times for breast mri, and to create a list of evidence-based indications for breast mri.

METHODS

The indications for breast mri exams performed in September 2013 at our academic centre were audited. A multidisciplinary meeting held in May 2014 established a list of evidence-based indications for breast mri, after which, in September 2014 and 2015, breast mri exams were re-audited for clinical indications, and pending requests were calculated.

RESULTS

In September 2013, surveillance of women with a prior diagnosis of breast cancer represented 21% of breast mri exams (24 of 113), with preoperative staging representing 18% of exams (20 of 113) and high-risk screening representing 12% (13 of 113). Of pending mri requests, 230 were within the recommended delay period, and 457 exceeded the recommended delay. After elaboration of evidence-based guidelines, repeat audits in September 2014 and September 2015 showed that mri performed for women with a prior breast cancer diagnosis represented 23% (33 of 141) and 7% (10 of 143) of exams respectively, with preoperative staging having declined to 9% (13 of 141) and 11% (16 of 143) of exams, and high-risk screening having increased to 36% (51 of 141) and 46% (66 of 143) of exams. Overall, wait times were improved for all breast mri indications.

CONCLUSIONS

Through multidisciplinary discussion, we actualized a list of breast mri indications, prioritized requests more adequately, and improved wait times.

Respiratory-gated KES imaging of a rat model of acute lung injury at the Canadian Light Source

In this study, contrast-enhanced X-ray tomographic imaging for monitoring and quantifying respiratory disease in preclinical rodent models is proposed. A K-edge imaging method has been developed at the Canadian Light Source to very accurately obtain measurements of the concentration of iodinated contrast agent in the pulmonary vasculature and inhaled xenon in the airspaces of rats. To compare the iodine and xenon concentration maps, a scout projection image was acquired to define the region of interest within the thorax for imaging and to ensure the same locations were imaged in each K-edge subtraction (KES) acquisition. A method for triggering image acquisition based on the real-time measurements of respiration was also developed to obtain images during end expiration when the lungs are stationary, in contrast to other previously published studies that alter the respiration to accommodate the image acquisition. In this study, images were obtained in mechanically ventilated animals using physiological parameters at the iodine K-edge in vivo and at the xenon K-edge post mortem (but still under mechanical ventilation). The imaging techniques were performed in healthy Brown Norway rats and in age-matched littermates that had an induced lung injury to demonstrate feasibility of the imaging procedures and the ability to correlate the lung injury and the quantitative measurements of contrast agent concentrations between the two KES images. The respiratory-gated KES imaging protocol can be easily adapted to image during any respiratory phase and is feasible for imaging disease models with compromised lung function.

Modulating immunogenicity of factor IX by fusion to an immunoglobulin Fc domain: a study using a hemophilia B mouse model

Essentials Fc-fusion increases a therapeutic's half-life, but FcγR interactions may impact immunogenicity. Species-specific Fc-FcγR interactions allow for mechanistic in vivo studies using mouse models. Fc fusion modulates the immune response to factor IX in hemophilia B mice by eliciting Th1 bias. This model could inform future studies of IgE-associated anaphylaxis in hemophilia B patients.

SUMMARY

Background Fc fusion is a platform technology used to increase the circulating half-life of protein and peptide therapeutics. However, there are potential immunological consequences with this approach, such as changes in the molecule's immunogenicity as well as possible interactions with a repertoire of Fc receptors (FcR) that can modulate immune responses. Objectives/Methods Using a mouse hemophilia B (HB) model, we compared the immune responses to infusions of recombinant human factor IX (hFIX) and hFIX fused to mouse IgG2a-Fc (hFIX-mFc). The mFc was employed to allow species-specific Fc-FcγR interactions. Results Although treatment with hFIX-mFc altered the early development of anti-FIX IgG, no significant differences in anti-FIX antibody titers were observed at the end of the treatment regimen (5 weeks) or upon anamnestic response (5 months). However, treatment with hFIX-mFc elicited higher FIX-neutralizing antibody levels and resulted in reduced IgE titers compared with the hFIX-treated group. Additionally, differences in plasma cytokine levels and in vitro CD4+ T-cell responses suggest that whereas hFIX treatment triggered a Th2-biased immune response, hFIX-mFc treatment induced Th1-biased CD4+ T cells. We also show that hFIX-mFc bound to soluble FcγRs and engaged with FcγRs on different cell types, which may impact antigen presentation. Conclusions These studies provide a model system to study how Fc-fusion proteins may affect immune mechanisms. We used this model to demonstrate a plausible mechanism by which Fc fusion may modulate the IgE response to hFIX. This model may be appropriate for investigating the rare but severe IgE-mediated anaphylaxis reaction to hFIX infusions in HB patients.

[Clinical characteristics and therapeutic effect of drug-resistant tuberculosis in children]

Objective: To explore the clinical characteristics of drug-resistant tuberculosis (TB) in children and to study the effectiveness of second-line anti-TB therapy for children and to examine the incidence of adverse drug reactions. Method: Retrospective research was conducted. The clinical records of children in West China Second Hospital diagnosed as drug-resistant TB from January 2010 to June 2014 were investigated.The clinical characteristics and risk factors were analyzed retrospectively. Treatment effect at discharge was examined as a short-term outcome indicator to evaluate the effectiveness of second-line anti-TB therapy and the incidence of adverse drug reactions. χ(2) test was used. Result: Forty-six patients were diagnosed as drug-resistant TB in 443 children infected with TB, with a 10.4% resistance rate. The 46 children included 26 male and 20 female patients, aged from one month and 28 days to 17 years and 5 months, with the average age (8.4±4.5) years, >7 to 14 years old patients as the biggest part(25 patients, 54.3%). Among the 46 children, 20 patients(43.5%)had close contact with TB patients, of whom 12 patients (60.0%) contacted with family members (including parents, brothers and sisters and grandparents living together) and 8 patients(40.0%) contacted with patients from outside family (such as relatives or neighbors). Moreover, 11 cases (23.9%) were under initial treatment and 35 cases (76.1%) were retreated.From 2010 to 2014, the number of cases of initial and retreated patients had no significant difference(0 and 1, 1 and 13, 4 and 7, 4 and 11, 2 and 3 cases, χ(2)=3.255, P=0.196). Among retreated patients, 31.4% (11/35) had irregular treatment before.Until discharge, the effective rate was 87.0% (40/46), while the incidence rate of adverse drug reaction was 10.9%(5/46). Conclusion: The therapy for drug-resistant TB is effective and the incidence of adverse drug reaction is relatively low.

Subcutaneous emphysema secondary to dental extraction: A case report

Although less frequently encountered in dental practices, subcutaneous emphysema of the face and neck has been reported in patients following dental extractions, particularly when lower molar teeth are extracted with the use of a high-speed air-turbine drill designed for restorative treatment, which forces air into the cervical fascial spaces. As facial swelling and pain are the most common presentations, subcutaneous emphysema can often be misdiagnosed as an allergic reaction or odontogenic infection. While usually a benign and self-limiting condition, subcutaneous emphysema may have life-threatening complications such as tension pneumothorax, cardiac tamponade, air embolism, tracheal compression and mediastinitis, which are important to recognize in an emergency setting. Dentists should be aware of the serious risks of inducing subcutaneous emphysema and avoid performing tooth extractions with high-speed air-turbine drills which are specifically designed for use for restorative treatments only.

Endoscopic monopolar coagulation of internal haemorrhoids: a surgeon's experience of the first 100 cases

AIM

The purpose of this study was to evaluate one surgeon's initial experience with a novel technique of retroflexed endoscopic coagulation of internal haemorrhoids.

METHOD

Patients who presented with symptoms and signs indicating Grade II-III haemorrhoids were counselled before the procedure. Those who were assessed to require an examination of their colon, based on their age and symptoms, underwent a full colonoscopy before treatment of the haemorrhoids. After the procedure, patients were routinely prescribed nonsteroidal anti-inflammatory drugs, antibiotics and laxatives.

RESULTS

The first 100 patients of median age 52.0 (20.8-78.5) years included 65 (65%) women. Five (5%) patients suffered from postprocedural complications, of which three (3%) were postprocedural bleeding and two (2%) were postprocedural pain, all treated conservatively. The recurrence rate was 6% at a median follow-up time of 36 (6-76) months. The median duration of follow-up was 36.5 (8.5-57.0) months.

CONCLUSION

This novel technique appears to be safe and effective for the treatment of Grade II-III internal haemorrhoids, and can be incorporated seamlessly into the end of a colonoscopy for the evaluation of haematochezia. Comparative trials should be performed.

Reduction of biological response modifiers in the supernatant of washed paediatric red blood cells

BACKGROUND

Washing of red blood cells (RBC) can reduce unwanted biological response modifiers (BRMs) that can mediate transfusion complications in infants. The aim of this study was to examine the in vitro quality and the changes in BRMs following washing in paediatric RBC units.

MATERIALS AND METHODS

A pool and split design was used to prepare RBC (either 1 or 4 days old; n = 26 pairs). One unit was washed with 0·9% saline by centrifugation and then resuspended in SAG-M, while the other remained unwashed. Each RBC unit was divided to produce four units of paediatric-sized components. Samples were taken after 3 h and subsequently on days 1, 2, 7 and 14 post-wash.

RESULTS

Washing of RBC resulted in some red cell loss, with a minor increase in haemolysis. Washing effectively reduced supernatant potassium and IgA, as well as cytokines and complement proteins. RBC microparticles were significantly reduced in RBC washed at 1, but not 4 days post-collection. Incubation with supernatant from unwashed but not washed RBC led to endothelial cell activation, with increased cell surface expression of CD62E (E-selectin) and CD106 (VCAM).

CONCLUSION

Although washing affected some aspects of the in vitro quality of RBC, it effectively reduced the concentration and activity of BRMs in the supernatant of RBC. Such a reduction may be clinically beneficial in selected patient groups.

A genome-wide association study of heat stress-associated SNPs in catfish

Heat tolerance is a complex and economically important trait for catfish genetic breeding programs. With global climate change, it is becoming an increasingly important trait. To better understand the molecular basis of heat stress, a genome-wide association study (GWAS) was carried out using the 250 K catfish SNP array with interspecific backcross progenies, which derived from crossing female channel catfish with male F1 hybrid catfish (female channel catfish × male blue catfish). Three significant associated SNPs were detected by performing an EMMAX approach for GWAS. The SNP located on linkage group 14 explained 12.1% of phenotypical variation. The other two SNPs, located on linkage group 16, explained 11.3 and 11.5% of phenotypical variation respectively. A total of 14 genes with heat stress related functions were detected within the significant associated regions. Among them, five genes-TRAF2, FBXW5, ANAPC2, UBR1 and KLHL29- have known functions in the protein degradation process through the ubiquitination pathway. Other genes related to heat stress include genes involved in protein biosynthesis (PRPF4 and SYNCRIP), protein folding (DNAJC25), molecule and iron transport (SLC25A46 and CLIC5), cytoskeletal reorganization (COL12A1) and energy metabolism (COX7A2, PLCB1 and PLCB4) processes. The results provide fundamental information about genes and pathways that is useful for further investigation into the molecular mechanisms of heat stress. The associated SNPs could be promising candidates for selecting heat-tolerant catfish lines after validating their effects on larger and various catfish populations.

Free fall trauma

In the abrupt vertical deceleration that occurs on impact after a free fall, tissue damage is caused by the absorption by the body of the energy accumulated during the free fall. Patients sustain a unique injury pattern that is predicatably different from that seen with other forms of blunt multiple trauma. The present paper reviews the pathophysiology and pattern of injury sustained following free fall.