Human target validation of phosphoinositide 3‐kinase (PI3K)β: effects on platelets and insulin sensitivity,using AZD6482 a novel PI3Kβ inhibitor

Nylander S, Kull B, Björkman JA, Ulvinge JC, Oakes N, Emanuelsson BM, Andersson M, Skärby T, Inghardt T, Fjellström O, Gustafsson D. Human target validation of phosphoinositide 3‐kinase (PI3K)β:effects on platelets and insulin sensitivity, using AZD6482 a novel PI3Kβ inhibitor. J Thromb Haemost 2012; 10: 2127–36. See also Jackson SP, Schoenwaelder SM. Antithrombotic phosphoinositide 3‐kinase β inhibitors in humans – a ‘shear’ delight! This issue, pp 2123–6. Summary. Background: Based on in vitro and animal data, PI3Kβ is given an important role in platelet adhesion and aggregation but its role in insulin signaling is unclear. Objective: To strengthen the PI3Kβ target validation using the novel, short‐acting inhibitor AZD6482. Methods and results: AZD6482 is a potent, selective and ATP competitive PI3Kβ inhibitor (IC₅₀ 0.01 μm ). A maximal anti‐platelet effect was achieved at 1 μm in the in vitro and ex vivo tests both in dog and in man. In dog, in vivo AZD6482 produced a complete anti‐thrombotic effect without an increased bleeding time or blood loss. AZD6482 was well tolerated in healthy volunteers during a 3‐h infusion. The ex vivo anti‐platelet effect and minimal bleeding time prolongation in the dog model translated well to data obtained in healthy volunteers. AZD6482 inhibited insulin‐induced human adipocyte glucose uptake in vitro (IC₅₀ of 4.4 μm ). In the euglycemic hyperinsulinemic clamp model, in rats, glucose infusion rate was not affected at 2.3 μm but reduced by about 60% at a plasma exposure of 27 μm . In man, the homeostasis model analysis (HOMA) index increased by about 10–20% at the highest plasma concentration of 5.3 μm . Conclusions: This is the first human target validation for PI3Kβ inhibition as anti‐platelet therapy showing a mild and generalized antiplatelet effect attenuating but not completely inhibiting multiple signaling pathways with an impressive separation towards primary hemostasis. AZD6482 at ‘supratherapeutic’ plasma concentrations may attenuate insulin signaling, most likely through PI3Kα inhibition.     

Fractures in the Maxillofacial Region: A Four Year Retrospective Study

Introduction

The incidence of maxillofacial injuries is on the rise due to motor vehicle accidents and increased incidence of violence in recent times. The aim of this retrospective study was to determine the incidence, aetiology, the pattern of fractures, their management with open reduction and internal fixation (ORIF) and complications, if any.

Methods

A retrospective analysis of 621 fractures in 361 patients managed by ORIF over a four year period was carried out.

Result

The average age of patients was 24.3 years with a male to female ratio of 21.2:1. Panfacial fractures comprised 4.7%, frontal bone fractures 8.9%, orbital fractures 0.7%, naso-orbito-ethmoid complex (NOE) fractures 0.7%, zygomatic complex fractures 23.5%, fracture maxilla 11.5% and mandibular fractures 52.2% of all facial fractures. All the cases were successfully managed by ORIF under general anaesthesia (GA). Complications were noticed in 6.8% of cases in the form of reactive implants in 3.6%, deranged occlusion in 1% and infection at operated site in 1% cases which were managed satisfactorily.

Conclusion

The findings of this study reveal sharp annual increase in the number of cases of maxillofacial trauma. Road traffic accidents (RTA) were the commonest cause and the age group most affected was between 20-25 years. ORIF of these fractures was chosen for its obvious advantages of direct anatomical reduction, early return to function and minimal complications.Key Words: Road traffic accidents (RTA), Inter maxillary fixation (IMF), Open reduction and internal fixation (ORIF)     

Outbreak of meningococcal infection amongst soldiers deployed in operations

Background: Meningococcal infection may lead to life threatening meningitis and fulminant meningococcal sepsis. Sporadic cases of meningococcal infection have been reported in soldiers but no outbreak in soldiers has been reported earlier from India. This outbreak in soldiers serving in counter insurgency role under field setting was effectively controlled without compromising their operational commitment.     

Internal fixation of fractures of both bones forearm: Comparison of locked compression and limited contact dynamic compression plate

Background:

The locking compression plate (LCP) with combination holes is a newer device in fracture fixation. We undertook a study comparing the LCP with limited contact dynamic compression plate (LC-DCP) in the treatment of diaphyseal fractures of both bones of the forearm.

Materials and Methods:

This is a prospective comparative study, 36 patients (18 in each group) with fractures of both the forearm bones (72 fractures) were treated with one of the two devices. The average age of the patients was 30.5 years (range 16–60 years) with mean followup of 2.1 years (range 1.5–2.8 years). The patients were assessed for fracture union and function and complications and by Disabilities of the Arm, Shoulder and Hand (DASH) score for patient related outcome at the latest followup.

Results:

There was no significant difference in two groups with respect to the range of movements or grip strength. One case had delayed union (LC-DCP group) and another had synostosis (LCP group). Plate removal was done in four cases within the study period with no refracture till the presentation of this report.

Conclusion:

LC plating is an effective treatment option for fractures of both bones of forearm. The present study could not prove its superiority over LC-DCP.     

Further genotype – phenotype correlations in neurofibromatosis 2

Selvanathan SK, Shenton A, Ferner R, Wallace AJ, Huson SM, Ramsden RT, Evans DG. Further genotype–phenotype correlations in neurofibromatosis 2. Neurofibromatosis 2 (NF2) is caused by mutations in the NF2 gene predisposing carriers to develop nervous system tumours. Different NF2 mutations result in either loss/reduced protein function or gain of protein function (abnormally behaving mutant allele i.e. truncated protein potentially causing dominant negative effect). We present a comparison between the clinical presentations of patients with mutations that are predicted to produce truncated protein (nonsense/frameshift mutations) to those that results in loss of protein expression (large deletions) to elucidate further genotype–phenotype correlations in NF2. Patients with nonsense/frameshift mutations have a younger age of diagnosis and a higher prevalence/proportion of meningiomas (p = 0.002, p = 0.014), spinal tumours (p = 0.004, p = 0.004) and non‐VIII cranial nerve tumours (p = 0.006, p = 0.003). We also found younger age of diagnosis of vestibular schwannomas (p = 0.007), higher mean numbers of cutaneous lesions (p = 0.003) and spinal tumours (p = 0.006) in these patients. With respect to NF2 symptoms, we found younger age of onset of hearing loss (p = 0.010), tinnitus (p = 0.002), paraesthesiae (p = 0.073), wasting and weakness (p = 0.001) and headaches (p = 0.049) in patients with nonsense/frameshift mutations. Our comparison shows, additional, new correlations between mutations in the NF2 gene and the NF2 disease phenotype, and this further confirms that nonsense/frameshift mutations are associated with more severe NF2 symptoms. Therefore patients with this class of NF2 mutation should be followed up closely.     

Sleep Deprivation Predisposes Gujarati Indian Adolescents to Obesity

Background and Aim:

Recent studies on various populations indicate that lack of sleep is one of the potential risk factors predisposing the youth to obesity. Since there is a significant rise in obesity among Indian youth and because research indicating the role of sleep in development of obesity among Indian population is scant, the current study was undertaken to assess the effect of sleep duration on adiposity among Gujarati Indian adolescents.

Materials and Methods:

A randomized cross-sectional study was done on 489 voluntarily participating Indian adolescents in the age group of 16-19 years. Participants were grouped into two categories 1). Adequate Sleep Duration at Night (more than seven hours, ASDN) and 2) Inadequate Sleep Duration at Night (less than seven hours, IASDN) as reported by the participants. The participants were later assessed for adiposity in terms of BMI, BF %, FM, FMI and waist circumference, meal frequency per day and physical activity status.

Results:

In both boys as well as girls, the BMI, BF%, FM and FMI were significantly lower in the ASDN group than the IASDN group. However, there was an insignificant difference in the meal frequency and physical activity status between the ASDN and IASDN group.

Conclusion:

Inadequate sleep duration increases adiposity among Gujarati Indian adolescents but further studies are required to find out the mechanisms through which sleep affects adiposity in this population.