Microcirculation in the foot is augmented by neuromuscular stimulation via the common peroneal nerve in different lower limb postures: a potential treatment for leg ulcers

AIM

Aim of the study was to examine the effects of the geko™ device (a portable electical nerve stimulator) on microcirculatory flow on the dorsum of the foot, and whether this is influenced by lower limb postures and application of a plaster cast.

METHODS

This was a cross-sectional, healthy cohort, open label, physiological response study. In 10 healthy volunteers, aged 19 to 24 years, laser Doppler fluxmetry measurements were made on the dorsum of the foot in four postures: standing (weight bearing and non-weight bearing) and supine lying (with the lower limb horizontal and then elevated). Measurements of flux were made both at rest and during stimulation with the geko™ device applied over the common peroneal nerve, at 1 Hz for 5 minutes in each posture. Repeat measurement were made after the application of a below knee plaster cast. Measures of flux were compared to basal levels assumed to be in supine with limb horizontal, with no cast and an inactive geko™ device.

RESULTS

The geko™ device was effective in increasing microcirculation on the dorsum of the foot in all four postures (mean difference =141%, 95% CI 70%-212%, P=0.001). This effect was more pronounced than that of using a plaster alone (Mean increase in flux of 73%, 95% CI 22%-125%, P=0.01) or variances due to the hydrostatic effects of different postures (mean difference 17-27.6%, P>0.05). There was a 2 to 3 fold increase in flux when stimulation was delivered in combination with the plaster cast.

CONCLUSION

Stimulation using the geko™ device augments microcirculation in the foot. The response is greater in lying and non-weight bearing than weight bearing standing but the most striking effect is when stimulation is combined with a plaster cast. The geko™ offers a potential means of promoting conditions favourable for wound healing, where treatment using compression may be contraindicated, such as arterial/mixed aetiology ulcers.

Vesicular glutamate transporter 2 and tyrosine hydroxylase are not co-localized in Syrian hamster nucleus accumbens afferents

The nucleus accumbens (NAc) is an important brain region for motivation, reinforcement, and reward. Afferents to the NAc can be divided into two anatomically segregated neurochemical phenotypes: dopaminergic inputs, primarily from the midbrain ventral tegmental area (VTA) and glutamatergic inputs from several cortical and sub-cortical structures. A population of glutamatergic neurons exists within the VTA and evidence from rats and mice suggests that these VTA axons may co-release dopamine and glutamate into the NAc. Our laboratory has used sexual experience in Syrian hamsters as a model of experience-dependent plasticity within the NAc. Given that both dopamine and glutamate are involved in this plasticity, it is important to determine whether these neurotransmitters are co-expressed within the mesolimbic pathway of hamsters. We therefore used immunofluorescent staining to investigate the possible co-localization of tyrosine hydroxylase (TH), a dopaminergic marker, and vesicular glutamate transporter 2 (VGLUT2), a glutamatergic marker, within the mesolimbic pathway. PCR analyses identified VGLUT2 gene expression in the VTA. No co-localization of TH and VGLUT2 protein was detected in NAc fibers, nor was there a difference in immunolabeling between males and females. Further studies are needed to resolve this absence of anatomical co-localization of TH and VGLUT2 in hamster striatal afferents with reports of functional co-release in other rodents.

Crofelemer, a novel antisecretory agent approved for the treatment of HIV-associated diarrhea

Secretory diarrhea has a significant impact on morbidity and mortality worldwide and may be a predominant or minor component of pathogenesis in diarrhea of various etiologies. Crofelemer is a first-in-class antidiarrheal medication with unique inhibitory mechanisms at both the cystic fibrosis transmembrane conductance regulator and the calcium-activated chloride channels which are responsible for chloride secretion and subsequent luminal hydration. The efficacy of crofelemer has been investigated in patients with HIV-associated diarrhea, diarrhea of various infectious etiologies, as well as diarrhea-predominant irritable bowel syndrome. Crofelemer was approved by the FDA in December 2012 to treat diarrhea in HIV/AIDS patients on antiretroviral therapy. Crofelemer is not absorbed in the body and well-tolerated in small trials performed to date although long-term safety data is lacking. Crofelemer may be an important addition to the currently available drugs for the management of secretory diarrhea.

Renal patients' views on generic prescribing and substitution: example from the United Arab Emirates

This survey examined current patient awareness and understanding of generic substitution. We surveyed 188 renal patients using 36 multiple-choice questions in 2 hospitals in the United Arab Emirates. We found that 70% of patients were aware of the availability of generic medicines, 60% understood the terms "generic" and "branded" in relation to medicines and 64% were conscious of generic substitution practice. However, 32% did not know if they were taking generics and 31% felt that generics were not equivalent or only sometimes equivalent to branded medicines. Nearly half (47%) the patients stated they would refuse generic substitution of ciclosporin when it became available if this was just to save the health authority money. In our opinion, random generic substitution should not be implemented because there is still uncertainty and lack of knowledge among patients.

A peculiar cause of bowel obstruction

INTRODUCTION

Gallstone disease is one of the most common surgical problems necessitating intervention. It is estimated that approximately 15% of people in the western world will develop gallstones. Of these patients, 35% of patients initially diagnosed with gallstones will later develop a complication which will eventually result in cholecystectomy.(2) One of these complications is gallstone ileus, which is a rare complication associated with high morbidity and mortality, and the diagnosis is often missed.(3)

PRESENTATION OF CASE

A 66 year old female presented with an acute onset of "colicky" abdominal pain accompanied with vomiting. She had known gallstones diagnosed previously by ultrasound. Her abdomen was generally tender with guarding of the right hypochondrium and absent bowel sounds.

DISCUSSION

Gallstone ileus accounts for 0.5-4% of all cases of small bowel obstruction, and typically affects females over the age of 65.(3,4) The pathophysiological basis of the disease involves fistulation of the gallstone through the wall of the gallbladder into the bowel, where it becomes impacted and leads to obstruction. Mortality of the condition is not sufficiently reported, but surgical intervention in itself conveys significant morbidity, and mortality has been reported to be 18%.(3,9)

CONCLUSION

We report a single large gallstone, which we believe to be one of the largest documented in recent literature, resulting in gallstone ileus. We also present a brief synopsis of the diagnosis and management of the condition, which although rare, should be considered by the astute surgical trainee.

Intelligent data analysis to model and understand live cell time-lapse sequences

BACKGROUND

One important aspect of cellular function, which is at the basis of tissue homeostasis, is the delivery of proteins to their correct destinations. Significant advances in live cell microscopy have allowed tracking of these pathways by following the dynamics of fluorescently labelled proteins in living cells.

OBJECTIVES

This paper explores intelligent data analysis techniques to model the dynamic behavior of proteins in living cells as well as to classify different experimental conditions.

METHODS

We use a combination of decision tree classification and hidden Markov models. In particular, we introduce a novel approach to "align" hidden Markov models so that hidden states from different models can be cross-compared.

RESULTS

Our models capture the dynamics of two experimental conditions accurately with a stable hidden state for control data and multiple (less stable) states for the experimental data recapitulating the behaviour of particle trajectories within live cell time-lapse data.

CONCLUSIONS

In addition to having successfully developed an automated framework for the classification of protein transport dynamics from live cell time-lapse data our model allows us to understand the dynamics of a complex trafficking pathway in living cells in culture.

Comparison of two policies for induction of labour postdates

The objective of this study was to compare maternal and midwifery manpower effects of policies for induction of labour (IOL) postdates, using a retrospective cohort design, in a level two maternity unit in a district hospital in South-West England. Primary outcome measures included mode of delivery, admission-delivery interval, midwifery manpower use. Group I consisted of 124 women who underwent IOL at 40+10. Group II were 104 women who underwent IOL at 42 weeks' gestation and 123 women who laboured spontaneously between 40+10 and 42 weeks' gestation. The nulliparous women had a shorter admission-delivery interval when induction was planned for 42 weeks, compared with 40+10 (p = 0.003), and required less frequent use of syntocinon (p = 0.04) and of continuous fetal monitoring (p = 0.02). The caesarean rate was higher in Group I than in Group II (p = 0.04) for nulliparous women only. The earlier induction policy was associated with a higher midwifery manpower requirement for nulliparae (p = 0.002). For parous women, the only difference was the greater use of oxytocin in labour. There was no difference between the groups in duration of labour, analgesia, Apgar scores, admission to neonatal care and meconium aspiration. In conclusion, delaying planned induction by three days was associated with lower medicalisation of labour and manpower needs for nulliparous women.

Stationary digital breast tomosynthesis with distributed field emission X-ray tube

Tomosynthesis requires projection images from different viewing angles. Using a distributed x-ray source this can be achieved without mechanical motion of the source with the potential for faster image acquisition speed. A distributed x-ray tube has been designed and manufactured specifically for breast tomosynthesis. The x-ray tube consists of 31 field emission x-ray sources with an angular range of 30°. The total dose is up to 100mAs with an energy range between 27 and 45 kVp. We discuss the source geometry and results from the characterization of the first prototype. The x-ray tube uses field emission cathodes based on carbon nanotubes (CNT) as electron source. Prior to the manufacturing of the sealed x-ray tube extensive testing on the field emission cathodes has been performed to verify the requirements for commercial tomosynthesis systems in terms of emission current, focal spot size and tube lifetime.

Literature-based priors for gene regulatory networks

MOTIVATION

The use of prior knowledge to improve gene regulatory network modelling has often been proposed. In this article we present the first research on the massive incorporation of prior knowledge from literature for Bayesian network learning of gene networks. As the publication rate of scientific papers grows, updating online databases, which have been proposed as potential prior knowledge in past research, becomes increasingly challenging. The novelty of our approach lies in the use of gene-pair association scores that describe the overlap in the contexts in which the genes are mentioned, generated from a large database of scientific literature, harnessing the information contained in a huge number of documents into a simple, clear format.

RESULTS

We present a method to transform such literature-based gene association scores to network prior probabilities, and apply it to learn gene sub-networks for yeast, Escherichia coli and Human organisms. We also investigate the effect of weighting the influence of the prior knowledge. Our findings show that literature-based priors can improve both the number of true regulatory interactions present in the network and the accuracy of expression value prediction on genes, in comparison to a network learnt solely from expression data. Networks learnt with priors also show an improved biological interpretation, with identified subnetworks that coincide with known biological pathways.

Intradural microsurgery and extradural gamma knife surgery for hypoglossal schwannoma: case report and review of the literature

There have been only 26 cases of hypoglossal schwannomas reported to originate intradurally and extend extradurally into the hypoglossal canal. This 31-year-old mother of two children presented with a 5-day history of progressive headache, nausea, vomiting and vertigo. Her neurological exam was significant for nystagmus and left tongue deviation with marked atrophy. An initial head CT revealed extensive left hypoglossal canal erosion with 4th ventricle compression. T1-weighted MR images with contrast revealed a 4x3 cm left cerebellopontine angle non-homogeneously enhancing mass with an intracranial cystic component and prominent extension into the eroded hypoglossal canal. A left lateral suboccipital craniotomy was performed for subtotal microsurgical resection of the intradural posterior fossa mass. A schwannoma was diagnosed after resection and gamma knife surgery (GKS) was performed three months later for the extradural residual tumor without further deficits. This is a rare report of a hypoglossal schwannoma in a young patient who was treated with a multimodality approach in order to minimize risks. A review of the literature and discussion of the respective benefits of microsurgery versus GKS and long-term follow-up issues are presented.

Organized tooth-specific cellular differentiation stimulated by BMP4

Mammalian teeth develop on the oral surface of the first pharyngeal arch by a series of reciprocal interactions between epithelial and mesenchymal cells. The embryonic first pharyngeal arch oral epithelium is able to induce tooth formation when combined with mesenchymal cells from the second pharyngeal arch, a region devoid of tooth development. Second pharyngeal arch mesenchyme is thus competent to form teeth if provided with the correct signals. First-arch oral epithelium expresses several signaling molecules that could be potential inducers of tooth development, including BMP4. The addition of BMP4 to intact second-arch explants resulted in the development of organized structures containing layers of cells that express marker genes of tooth-specific cells, odontoblasts and ameloblasts. Thus, although overt tooth development did not occur, BMP4 has the ability to stimulate organized differentiation of epithelial- and mesenchymal-derived dental-specific cells from non-dental primordia.

Direct ANP inhibition of hypoxia-induced inflammatory pathways in pulmonary microvascular and macrovascular endothelial monolayers

Atrial natriuretic peptide (ANP) has been shown to reduce hypoxia-induced pulmonary vascular leak in vivo, but no explanation of a mechanism has been offered other than its vasodilatory and natriuretic actions. Recently, data have shown that ANP can protect endothelial barrier functions in TNF-alpha-stimulated human umbilical vein endothelial cells. Therefore, we hypothesized that ANP actions would inhibit pulmonary vascular leak by inhibition of TNF-alpha secretion and F-actin formation. Bovine pulmonary microvascular (MVEC) and macrovascular endothelial cell (LEC) monolayers were stimulated with hypoxia, TNF-alpha, or bacterial endotoxin (LPS) in the presence or absence of ANP, and albumin flux, NF-kappa B activation, TNF-alpha secretion, p38 mitogen-activated protein kinase (MAPK), and F-actin (stress fiber) formation were assessed. In Transwell cultures, ANP reduced hypoxia-induced permeability in MVEC and TNF-alpha-induced permeability in MVEC and LEC. ANP inhibited hypoxia and LPS increased NF-kappa B activation and TNF-alpha synthesis in MVEC and LEC. Hypoxia decreased activation of p38 MAPK in MVEC but increased activation of p38 MAPK and stress fiber formation in LEC; TNF-alpha had the opposite effect. ANP inhibited an activation of p38 MAPK in MVEC or LEC. These data indicate that in endothelial cell monolayers, hypoxia activates a signal cascade analogous to that initiated by inflammatory agents, and ANP has a direct cytoprotective effect on the pulmonary endothelium other than its vasodilatory and natriuretic properties. Furthermore, our data show that MVEC and LEC respond differently to hypoxia, TNF-alpha-stimulation, and ANP treatment.

Assessing inhibitory control: a revised approach to the stop signal task

The stop signal task (stop task) is designed to assess inhibitory control and is a frequently used research tool in clinical disorders such as ADHD and schizophrenia. Previous methods of setting stop signal delay and of assessing inhibitory control are problematic. The current study reports two modifications that improve the task as a measure of inhibitory control. The first modification was to set stop signal delays proportional to go mean reaction time (go MRT) to better account for inter-subject variability in go MRT. Twenty-eight normal children were tested, and all standard, stop task dependent measures were obtained when delays were set by this method. The second modification was to calculate a novel dependent measure called the area of inhibition (AOI) which provides a more complete measure of inhibitory control than the slope of the relative finishing time z-scores (ZRFT-slope). Implications for the assessment of inhibitory control in clinical populations are discussed.

Potentiation by ketamine of fentanyl antinociception. I. An experimental study in rats showing that ketamine administered by non-spinal routes targets spinal cord antinociceptive systems

BACKGROUND

Ketamine has been found to exert antinociceptive effects in animals and to be analgesic at subanaesthetic doses in humans. This study was designed to investigate the involvement of spinal cord mechanisms in the potentiation of opioid analgesia by parenteral non-spinal administration of ketamine.

METHODS

Thresholds for nociception were measured in an acute pain model in rats that allowed identification of antinociceptive effects due to drug action in the spinal cord. Dose-response curves for the antinociceptive effects of ketamine alone and ketamine in conjunction with the mu opioid fentanyl were constructed.

RESULTS

Intraperitoneal ketamine up to 3.75 mg kg(-1) caused no sedative or antinociceptive effects and intrathecal ketamine caused dose-dependent, spinally mediated antinociceptive effects. Injections of ketamine doses that caused no antinociceptive effects when given alone (intrathecal 25 microg and intraperitoneal 3.75 mg/kg) significantly increased spinally mediated antinociception produced by intrathecal fentanyl injections when assessed using noxious heat (tail-flick test) but not when assessed by noxious electrical current (electrical current threshold test).

CONCLUSIONS

We conclude that ketamine can potentiate the effects of fentanyl by an interaction at the level of the spinal cord even when ketamine is given via a non-spinal route of administration.