Melatonin and vitamin C increase umbilical blood flow via nitric oxide-dependent mechanisms

Inadequate umbilical blood flow leads to intrauterine growth restriction, a major killer in perinatal medicine today. Nitric oxide (NO) is important in the maintenance of umbilical blood flow, and antioxidants increase NO bioavailability. What remains unknown is whether antioxidants can increase umbilical blood flow. Melatonin participates in circadian, seasonal, and reproductive physiology, but has also been reported to act as a potent endogenous antioxidant. We tested the hypothesis that treatment during pregnancy with melatonin increases umbilical blood flow via NO-dependent mechanisms. This was tested in pregnant sheep by investigating in vivo the effects on continuous measurement of umbilical blood flow of melatonin before and after NO blockade with a NO clamp. These effects of melatonin were compared with those of the traditional antioxidant, vitamin C. Under anesthesia, 12 pregnant sheep and their fetuses (0.8 of gestation) were fitted with catheters and a Transonic probe around an umbilical artery, inside the fetal abdomen. Following 5 days of recovery, cardiovascular variables were recorded during fetal i.v. treatment with either melatonin (n=6, 0.5±0.1 μg/kg/min) or vitamin C (n=6, 8.9±0.4 mg/kg/min) before and after fetal NO blockade with the NO clamp. Fetal treatment with melatonin or vitamin C increased umbilical blood flow, independent of changes in fetal arterial blood pressure. Fetal NO blockade prevented the increase in umbilical blood flow induced by melatonin or vitamin C. Antioxidant treatment could be a useful clinical tool to increase or maintain umbilical blood flow in complicated pregnancy.     

Retrospective evaluation of clinical outcomes in subjects with split‐thickness skin graft: comparing V.A.C.® therapy and conventional therapy in foot and ankle reconstructive surgeries

This retrospective study compared the clinical outcomes of negative pressure wound therapy with reticulated open cell foam (NPWT/ROCF) as delivered by Vacuum‐Assisted Therapy^® (V.A.C.^® Therapy, KCI Licensing Inc., San Antonio, TX) to non‐NPWT/ROCF conventional therapy (CT) in split‐thickness skin graft (STSG) survival in all patients to determine whether NPWT/ROCF affects the outcome of the graft survival, in terms of overall graft take, duration of graft take, repeated grafts and complications. The authors conducted a 10‐year retrospective review of 142 patients admitted to a level I trauma centre and treated with an STSG in foot and ankle reconstructive surgeries. Demographic data, wound etiology, dressing type used, time to graft take, NPWT/ROCF duration, complications and outpatient treatments were analysed. There were significantly fewer repeated STSGs required in the NPWT/ROCF group compared to CT [n = 3 (3·5%) versus n = 9 (16%); P = 0·006]. In assessing safety, there were fewer complications in graft failure (seroma, hematoma and infection) in the NPWT/ROCF group as compared to the CT group at 8·9 months (range: 1–12 months). NPWT/ROCF is an excellent alternative for securing an STSG and is associated with improved graft survival as measured by a reduction in the number of repeated STSGs and graft failure complications.     

Assessment of calcification and inflammation with positron emission tomography in aortic stenosis and atherosclerosis

BackgroundCalcification and inflammation are key pathological processes in aortic stenosis and atherosclerosis. Using combined positron emission tomography and computed tomography (PET/CT), we sought to investigate their contribution to disease progression in aortic stenosis and to help identify vulnerable atherosclerotic plaque.MethodsIn the first part of the study patients with calcific aortic valve disease stenosis were prospectively compared with age-matched and sex-matched controls with normal valves. Aortic valve severity was determined at baseline and 1 year by echocardiography and CT calcium scoring. Calcification and inflammation in the valve were assessed by sodium 18-fluoride (NaF) and 18-fluorodeoxyglucose (FDG) uptake with PET. In the second part of the study NaF and FDG activity was assessed in the coronary arteries both in patients with stable coronary disease and in patients after myocardial infarction.Findings101 patients with aortic stenosis were compared with 20 controls. Tracer activity (target to background ratio [TBR]) was higher in patients with aortic stenosis than in controls (mean NaF 2·87 [SD 0·82] vs 1·55 [0·17], FDG 1·58 [0·21] vs 1·30 [0·13]; both p<0·01). NaF uptake displayed a progressive rise with valve severity (r²=0·540) with a more modest increase observed for FDG (r²=0·218). Baseline NaF correlated closely with alkaline phosphatase staining on immunohistochemistry (r²=0·79) and was a better predictor of disease progression at 1 year (r²=0·44, n=20) than was FDG (r²=0·02) or baseline calcium score (r²=0·36, current best predictor). Increased NaF activity was observed in 45 (42%) of 106 patients with stable coronary atherosclerosis and was localised to individual coronary plaques. These patients had higher rates of previous major adverse cardiovascular events (p=0·016) and higher Framingham risk scores (p=0·011) than did patients without increased uptake. In patients after myocardial infarction (n=15) intense NaF activity was observed at the site of the culprit lesion, with increased uptake compared with the maximum uptake elsewhere in the coronary arteries (TBR median 1·56 [IQR 1·49–1·82] vs 1·23 [1·15–1·48], p=0·02).InterpretationIn the valve, NaF holds promise in predicting aortic stenosis progression. In the coronary arteries it identifies culprit plaque post myocardial infarction and stable patients at elevated cardiac risk.FundingBritish Heart Foundation.     

Post-cardiac arrest temperature manipulation alters early EEG bursting in rats

OBJECTIVES: Hypothermia improves outcomes after cardiac arrest (CA), while hyperthermia worsens injury. EEG recovers through periodic bursting from isoelectricity after CA, the duration of which is associated with outcome in normothermia. We quantified burst frequency to study the effect of temperature on early EEG recovery after CA. METHODS: Twenty-four rats were divided into three groups, based on 6h of hypothermia (T=33 degrees C), normothermia (T=37 degrees C), or hyperthermia (T=39 degrees C) immediately post-resuscitation from 7-min asphyxial CA. Temperature was maintained using surface cooling and re-warming. Neurological recovery was defined by 72-h neurological deficit score (NDS). RESULTS: Burst frequency was higher during the first 90min in rats treated with hypothermia (25.6+/-12.2min(-1)) and hyperthermia (22.6+/-8.3min(-1)) compared to normothermia (16.9+/-8.5min(-1)) (p<0.001). Burst frequency correlated strongly with 72-h NDS in normothermic rats (p<0.05) but not in hypothermic or hyperthermic rats. The 72-h NDS of the hypothermia group (74, 61-74; median, 25-75th percentile) was significantly higher than the normothermia (49, 47-61) and hyperthermia (43, 0-50) groups (p<0.001). CONCLUSIONS: In normothermic rats resuscitated from CA, early EEG burst frequency is strongly associated with neurological recovery. Increased bursting followed by earlier restitution of continuous EEG activity with hypothermia may represent enhanced recovery, while heightened metabolic rate and worsening secondary injury is likely in the hyperthermia group. These factors may confound use of early burst frequency for outcome prediction.     

GSK1562590, a slowly dissociating urotensin-II receptor antagonist, exhibits prolonged pharmacodynamic activity ex vivo

BACKGROUND AND PURPOSE

Recently identified antagonists of the urotensin–II (U-II) receptor (UT) are of limited utility for investigating the (patho)physiological role of U-II due to poor potency and limited selectivity and/or intrinsic activity.

EXPERIMENTAL APPROACH

The pharmacological properties of two novel UT antagonists, GSK1440115 and GSK1562590, were compared using multiple bioassays.

KEY RESULTS

GSK1440115 (pK_i= 7.34–8.64 across species) and GSK1562590 (pK_i= 9.14–9.66 across species) are high affinity ligands of mammalian recombinant (mouse, rat, cat, monkey, human) and native (SJRH30 cells) UT. Both compounds exhibited >100-fold selectivity for UT versus 87 distinct mammalian GPCR, enzyme, ion channel and neurotransmitter uptake targets. GSK1440115 showed competitive antagonism at UT in arteries from all species tested (pA₂= 5.59–7.71). In contrast, GSK1562590 was an insurmountable UT antagonist in rat, cat and hUT transgenic mouse arteries (pK_b= 8.93–10.12 across species), but a competitive antagonist in monkey arteries (pK_b= 8.87–8.93). Likewise, GSK1562590 inhibited the hU-II-induced systemic pressor response in anaesthetized cats at a dose 10-fold lower than that of GSK1440115. The antagonistic effects of GSK1440115, but not GSK1562590, could be reversed by washout in rat isolated aorta. In ex vivo studies, GSK1562590 inhibited hU-II-induced contraction of rat aorta for at least 24 h following dosing. Dissociation of GSK1562590 binding was considerably slower at rat than monkey UT.

CONCLUSIONS AND IMPLICATIONS

Whereas both GSK1440115 and GSK1562590 represent high-affinity/selective UT antagonists suitable for assessing the (patho)physiological role of U-II, only GSK1562590 exhibited sustained UT residence time and improved preclinical efficacy in vivo.     

Formulation and evaluation of mouth dissolving tablets of cinnarizine

The purpose of this research was to develop mouth dissolve tablets of cinnarizine by effervescent, superdisintegrant addition and sublimation methods. All the three formulations were evaluated for disintegration time, hardness and friability, among these superdisintegrant addition method showed lowest disintegration time; hence it was selected for further studies. Further nine batches (B1-B9) were prepared by using crospovidone, croscarmellose sodium and L-HPC in different concentrations such as 5, 7.5 and 10%. All the formulations were evaluated for weight variation, hardness, friability, drug content, in vitro disintegration time, wetting time, in vitro dissolution. Formulation with 10% L-HPC showed the less disintegration time (25.3 s) and less wetting time (29.1 s). In vitro dissolution studies showed total drug release at the end of 6 min.     

High spatiotemporal resolution imaging of the neurovascular response to electrical stimulation of rat peripheral trigeminal nerve as revealed by in vivo temporal laser speckle contrast

Previous studies have implicated the abnormal activation of the trigeminal system to be a factor in the pathogenesis of migraine. The relationship between vascular changes and migraine, however, is under considerable debate. In this study, temporal laser speckle contrast imaging is combined with ridge tracking based vessel detection to obtain high resolution (6.7 microm x 6.7 microm), high contrast images of cerebral vascular structure. For the first time, the vasomotor and blood flow responses to electrical stimulation in rat peripheral trigeminal system were obtained simultaneously. The system is capable of picking up individual vessels with diameters down to 30 microm. The spatial spread of the blood velocity response relative to the point of stimulation was studied. Analysis of branching vessels showed a 50+/-5% vs. 30+/-5% change in mean peak magnitude and a 54% per second vs. 17% per second change in mean rate of increase for vessels proximal vs. distal to the stimulation site. The penetration depth of the laser used was proven to be sufficient to image dural as well as cortical vessels through a thinned skull preparation. Different responses were observed from cortical and dural vessels. While the diameter of cortical vessels did not change in response to the stimulation the blood velocity went up by 65+/-5% per second. Dural vessels enlarged by 40+/-8% and the blood velocity increased by 50+/-5%. The method described here could be very useful in understanding and studying disorders in the neurovascular system.