Myogenic contractions of a somatic muscle powers rhythmic flow of hemolymph through Drosophila antennae and generates brain pulsations

Hemolymph is driven through the antennae of Drosophila melanogaster by the rhythmic contraction of muscle 16 (m16), which runs through the brain. Contraction of m16 results in the expansion of an elastic ampulla, opening ostia and filling the ampulla. Relaxation of the ampullary membrane forces hemolymph through vessels into the antennae. We show that m16 is an auto-active rhythmic somatic muscle. The activity of m16 leads to the rapid perfusion of the antenna by hemolymph. In addition, it leads to the rhythmic agitation of the brain, which could be important for clearing the interstitial space.

Assembly of the Cardiac Pacemaking Complex: Electrogenic Principles of Sinoatrial Node Morphogenesis

Cardiac pacemaker cells located in the sinoatrial node initiate the electrical impulses that drive rhythmic contraction of the heart. The sinoatrial node accounts for only a small proportion of the total mass of the heart yet must produce a stimulus of sufficient strength to stimulate the entire volume of downstream cardiac tissue. This requires balancing a delicate set of electrical interactions both within the sinoatrial node and with the downstream working myocardium. Understanding the fundamental features of these interactions is critical for defining vulnerabilities that arise in human arrhythmic disease and may provide insight towards the design and implementation of the next generation of potential cellular-based cardiac therapeutics. Here, we discuss physiological conditions that influence electrical impulse generation and propagation in the sinoatrial node and describe developmental events that construct the tissue-level architecture that appears necessary for sinoatrial node function.

Anti-ulcer property of methanol fraction of Callichilia subsessilis leaf extract in albino rats

Peptic ulcer is one of the major causes of morbidity and mortality worldwide. It is treated with herbal preparations in developing countries. This study investigated the anti-ulcer property of methanol fraction of Callichilia subsessilis leaf in albino rats. Methanol extract prepared through the cold maceration method was partitioned into chloroform and methanol fraction using a separating funnel. The methanol fraction of Callichilia subsessilis (MFCS) was concentrated in vacuo using a rotary evaporator. The acute toxicity was determined using the brine shrimp lethality test and the up-and-down method at a dose limit of 2000 mg/kg. The anti-ulcer activity of MFCS was evaluated at the doses of 12.5, 25 and 50 mg/kg using indomethacin-and ethanol-induced ulcer models. Misoprostol was used as a reference standard. The ulcer score, index and severity were determined using standard methods. Isolated rabbit jejunum tissue in Tyrode’s solution was used to establish the possible mechanism of anti-ulcer activity of MFCS. The LC50 and LD50 of MFCS were greater than 10,000 ppm and 2,000 mg/kg respectively. The MFCS exhibited significant (p < 0.05) dose-dependent anti-ulcer activity in all the ulcer models used. The MFCS (25 mg/kg) produced 52% and 41.33% inhibition of ulcer index in the indomethacin- and ethanol-induced ulcer models respectively. In the isolated tissue model, MFCS caused significant (p < 0.05) relaxation of the rhythmic contraction of the isolated rabbit jejunum and partially inhibited acetylcholine- and histamine-induced contraction of the jejunal smooth muscles. In conclusion, MFCS exhibited anti-ulcer (antihistaminic and anticholinergic) effects. This study justified the use of Callichilia subsessilis leaves in traditional medicine as an anti-ulcer remedy.

Physiological control of respiration

Respiration involves the inward and outward movement of air into the lungs. This process facilitates gaseous exchange. The rate of respiration therefore regulates the partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the blood. Spontaneous respiration occurs as a result of rhythmic discharge of motor neurons innervating respiratory muscles. Nerve impulses from the brain are responsible for this rhythmic discharge. The rhythmic contraction and relaxation of respiratory muscles alternatively fill the lungs during inspiration and empty them in expiration. This rhythmic discharges from the brain are regulated by changes in arterial PaO2, PaCO2 and hydrogen ion (H+) concentration, which is called the chemical control of respiration.

Control of sinus venous valve and sinoatrial node development by endocardial NOTCH1

Aims Sinus venous valve (SVV) and sinoatrial node (SAN) develop together at the sinoatrial junction during embryogenesis. SVV ensures unidirectional cardiac input and SAN generates sinus rhythmic contraction, respectively; both functions are essential for embryonic survival. We aim to reveal the potential role of endocardial NOTCH signalling in SVV and SAN formation. Methods and results We specifically deleted Notch1 in the endocardium using an Nfatc1Cre line. This deletion resulted in underdeveloped SVV and SAN, associated with reduced expression of T-box transcription factors, Tbx5 andTbx18, which are essential for the formation of SVV and SAN. The deletion also led to decreased expression of Wnt2 in myocardium of SVV and SAN. WNT2 treatment was able to rescue the growth defect of SVV and SAN resulted from the Notch1 deletion in whole embryo cultures. Furthermore, the Notch1 deletion reduced the expression of Nrg1 in the SVV myocardium and supplement of NRG1 restored the growth of SVV in cultured Notch1 knockout embryos. Conclusion Our findings support that endocardial NOTCH1 controls the development of SVV and SAN by coordinating myocardial WNT and NRG1 signalling functions.

Rhythms of the Body, Rhythms of the Brain: Respiration, Neural Oscillations, and Embodied Cognition

In spite of its importance as a life-defining rhythmic movement and its constant rhythmic contraction and relaxation of the body, respiration has not received attention in Embodied Cognition (EC) literature. Our paper aims to show that (1) respiration exerts significant and unexpected bottom-up influence on cognitive processes, and (2) it does so by modulating neural synchronization that underlies specific cognitive processes. Then, (3) we suggest that the particular example of respiration may function as a model for a general mechanism through which the body influences cognitive functioning. Finally, (4) we work out the implications for embodied cognition, draw a parallel to the role of gesture, and argue that respiration sometimes plays a double, pragmatic and epistemic, role, which reduces the cognitive load. In such cases, consistent with EC, the overall cognitive activity includes a loop-like interaction between neural and non-neural elements. (141 words)

Essential Palatal Myoclonus

Introduction: Palatal myoclonus is a rare condition presenting with clicking sound in ear or muscle tremor in pharynx. There are two varieties: essential and symptomatic. Various treatment options exists ranging from watchful observation to botulinum toxin injection. We have not found any reported case of palatal myoclonus from our country. Here we present a case of essential palatal myoclonus managed with clonazepam. Case report: A young female presented in Ear Nose and Throat clinic with complain of auditory click and spontaneous rhythmic movement of throat muscles for eight months. On examination, there was involuntary, rhythmic contraction of bilateral soft-palate, uvula, and base of tongue. Neurological, eye, and peripheral examination were normal. A diagnosis of essential palatal myoclonus was made. It was managed successfully with clonazepam; patient was still on low dose clonazepam at the time of making this report. Conclusion: Essential palatal myoclonus can be clinically diagnosed and managed even in settings where MRI is not available or affordable.

A Mechatronic Pneumatic Device to Improve Diastolic Function by Intermittent Action on Lower Limbs

Individuals with walking disability, as a result of pathological conditions or traumas, show a reduction in left ventricle end diastolic volume (EDV). In fact EDV is closely related to the blood pressure gradient between the postcaval vein and the right atrium which, during locomotion, is partially due to the calf veins squeezing caused by the rhythmic contraction of the triceps surae and the crushing of the sole of the foot’s veins. In this study, a mechatronic device was applied to nineteen healthy voluntary participants’ lower limbs to test cardiodynamic response to a mechanical intermittent stimulation. The device consisted of inflatable bladders embedded in two shells and acting on the skin of the calf and foot of both legs. The pressure trend on the legs was regulated by a portable programmable logic controller. During the compression protocol to the legs, which involved some sequences of activation-deactivation following a peristaltic compression having a caudal-rostral trend, EDV, assessed by the impedance cardiography technique, increased of about 10% up the pre-test value. The legs compression protocol imposed by means of our pneumatic device might be useful to avoid the negative consequences for cardiovascular performance caused by de-conditioning status linked to walking disabilities.