Form, Function, Agency: Sources of Natural Purpose in Animal Evolution

The origination and evolution of multicellular form and function is generally thought to be based on gene-based variation, with natural selection changing the populational composition in the respective variants over time. The criterion for evolutionary success is differential fitness, the relative capacity to leave progeny in the next generation. Theoretical considerations show that this model implies that phenotypic evolution will generally be gradual, based on variations of small effect. But the fossil record of early phylogenesis, notably for the metazoans, or animals, does not support the gradualist scenario. Moreover, discordances of phenotype and genotype in extant species, along with the existence of a pan-metazoan developmental genetic toolkit, does not support the gene-variation-based evolutionary mechanism, at least at the level of phyla. Most importantly, all life-forms, including the cells that constitute animal embryos, exhibit agency, and associations of cells (even constructed ones with no history of natural selection) exhibit novel kinds of agency. This strongly suggests that new multicellular forms can invent new ways of life (e.g., ecological niches) and can persist without supplanting their populational cohorts. This chapter describes how anatomical (e.g., segments, appendages) and functional (e.g., muscle, nerve) phenotypes can emerge without cycles of gradual selection from inherent properties of metazoan cells and their aggregates. While such phenotypic “add-ons” could provide enablements for exploration of new niches, it is implausible that they arose as adaptations to external challenges. Reproductive fitness, which is essential for understanding biogeography and ecology, is unlikely to have played a role in phylum-level evolution.

Development and Usability Testing of a Finger Grip Enhancer for the Elderly

As people age, their finger function deteriorates due to muscle, nerve, and brain degeneration. While exercises might delay this deterioration, an invention that enhances elderly people’s pinching abilities is essential. This study aims to design and develop a finger grip enhancer that facilitates the day-to-day pinching activities of elderly people. This research is an extension of a previous study that conceptualised a finger grip enhancer. The device facilitates finger flexion on the thumb and index finger, and weighs 520 g, allowing for improved portability and sufficient force exertion (13.9 N) for day-to-day pinching. To test for usability, eleven subjects aged 65 years and above performed a pinch-lift-hold test on various household objects. The pinch force before and after utilising the device was measured. Using Minitab 18, the statistical significance of using this device was analysed with a paired-samples t-test. With this device, the elderly people’s pinching abilities significantly improved in both pinch force and pinch force steadiness (p < 0.05). The proposed device has the potential to enhance elderly people’s quality of life by supporting a firm pinch in the handling of everyday objects. This research has applicational value in developing exoskeleton devices for patients who require rehabilitation.

Effects of Modified Osteoplastic Pterional Craniotomy on Temporal Muscle Volume and Frontal Muscle Nerve Function

Introduction Pterional craniotomy is a surgical approach frequently used in aneurysm and skull base surgery. Pterional craniotomy may lead to cosmetic and functional problems, such as eyebrow drop due to facial nerve frontal branch damage, temporal muscle atrophy, and temporomandibular joint pain. The aim was to compare the postoperative effects of our modified osteoplastic craniotomy with classical pterional craniotomy in terms of any change in volume of temporal muscle and in the degree of frontal muscle nerve damage. Materials and Methods Aneurysm cases were operated with either modified osteoplastic pterional craniotomy or free bone flap pterional craniotomy according to the surgeon's preference. Outcomes were compared in terms of temporal muscle volume and frontal muscle nerve function 6 months postoperatively. Results Preoperative temporal muscle volume in the modified osteoplastic pterional and free bone flap pterional craniotomy groups were not different (p > 0.05). However, significantly less atrophy was observed in the postoperative temporal muscle volume of the osteoplastic group compared with the classical craniotomy group (p < 0.001). In addition, when comparing frontal muscle nerve function there was less nerve damage in the modified osteoplastic pterional craniotomy group compared with the classical craniotomy group, although this did not reach significance (p > 0.05). Conclusion Modified osteoplastic pterional craniotomy significantly reduced atrophy of temporal muscle and caused proportionally less frontal muscle nerve damage compared with pterional craniotomy, although this latter outcome was not significant. These findings suggest that osteoplastic craniotomy may be a more advantageous intervention in cosmetic and functional terms compared with classical pterional craniotomy.

Different Concentrations of Ropivacaine under Ultrasound Guidance on Quadratus Lumbar Muscle Nerve Block in Elderly Patients with Hip Replacement

Objective. To compare the effect of ropivacaine in different concentrations under ultrasound guidance on lumbar muscle nerve blocking in elderly patients undergoing hip replacement surgery. Methods. 60 elderly patients underwent hip replacement in our hospital over a period of April to December of 2019 were equally randomized into control and observation groups, with 30 each. Patients in the control group and observation group received 0.5% and 0.25% ropivacaine to block psoas muscle nerve, respectively. The anesthetic effect of ropivacaine at different concentrations was evaluated by time of sensory block onset and recovery and time of motor block onset and regression, blood pressure, heart rate, visual analogy scale, and postoperative nerve blocking degree. Results. The onset time of sensory and motor block in the observation group was dramatically higher than that in the control group ( P < 0.05 ), while the recovery time of sensory and motor was significantly shorter than that of the control group ( P < 0.05 ). The heart rate in the observation group was notably lower than that in the control group, while the average blood pressure was remarkably higher ( P < 0.05 ). After surgery, the degree of nerve block in the observation group was much lower compared with the control group ( P < 0.05 ), while no marked difference in the visual analogue scale in the control group before and after surgical intervention was observed ( P > 0.05 ). Conclusion. The 0.25% ropivacaine method has distinctive advantages over 0.50% ropivacaine psoas nerve anesthesia in hip replacement surgery in elderly patients.

Muscle-Nerve-Nerve Grafting Improves Facial Reanimation in Rats Following Facial Nerve Injury

Nerve injury resulting in muscle paralysis from trauma or surgery is a major medical problem. Repair of such injuries with existing nerve grafting and reconstructive techniques often results in less than optimal outcomes. After previously demonstrating significant return of function using muscle-nerve-muscle (MNM) grafting in a rat facial nerve model, this study compares a variant of the technique, muscle-nerve-nerve (MNN) neurotization to MNM and interposition (IP) nerve grafting. Thirty male rats were randomized into four groups (1) control with no intervention, (2) repair with IP grafts, (3) MNM grafts and (4) MNN grafts. All groups had the buccal and marginal mandibular branches of the right facial nerve resected. Return of vibrissae movement, orientation, and snout symmetry was measured over 16 weeks. Functional recovery and muscle atrophy were assessed and quantified. All interventions resulted in significant improvement in vibrissae movement and orientation as compared to the control group (p &lt; 0.05). The MNM and MNN groups had significantly less time to forward vibrissae movement as compared to controls (p &lt; 0.05), and a large number of animals in the MNN group had coordinated vibrissae movement at 16 weeks. MNN and IP grafts retained significantly more muscle mass as compared to control (p &lt; 0.05). Thus, MNN grafting is a promising adjuvant or alternative technique for reanimation for patients with unilateral peripheral nerve injury who are not candidates for primary neurorrhaphy.

Optogenetically controlled human functional motor endplate for testing botulinum neurotoxins

Background The lack of physiologically relevant and predictive cell-based assays is one of the major obstacles for testing and developing botulinum neurotoxins (BoNTs) therapeutics. Human-induced pluripotent stem cells (hiPSCs)-derivatives now offer the opportunity to improve the relevance of cellular models and thus the translational value of preclinical data. Methods We investigated the potential of hiPSC-derived motor neurons (hMNs) optical stimulation combined with calcium imaging in cocultured muscle cells activity to investigate BoNT-sensitivity of an in vitro model of human muscle-nerve system. Results Functional muscle-nerve coculture system was developed using hMNs and human immortalized skeletal muscle cells. Our results demonstrated that hMNs can innervate myotubes and induce contractions and calcium transient in muscle cells, generating an in vitro human motor endplate showing dose-dependent sensitivity to BoNTs intoxication. The implementation of optogenetics combined with live calcium imaging allows to monitor the impact of BoNTs intoxication on synaptic transmission in human motor endplate model. Conclusions Altogether, our findings demonstrate the promise of optogenetically hiPSC-derived controlled muscle-nerve system for pharmaceutical BoNTs testing and development.

Rat skeletal muscle-nerve preparation to teach skeletal muscle physiology

This sourcebook update describes a variation of a previous sourcebook experiment that used isolated extensor digitorum longus muscle from mouse to teach skeletal muscle properties (Head and Arber, Adv Physiol Educ 37: 405-414, 2013; doi:10.1152/advan.00155.2012). Gastrocnemius-sciatic nerve preparation in an anaesthetized rat was developed and muscle contractions were recorded in a computerized data acquisition system using an isometric force transducer. Teachers and students in physiology or biology can use this preparation to demonstrate skeletal muscle properties like simple muscle twitch, quantal summation, wave summation, superposition, incomplete tetanus, complete tetanus, treppe, fatigue, and length-tension relationship.

A CADAVERIC STUDY OF COMMON PERONEAL NERVE IN RELATION TO FIBULAR TUNNEL

INTRODUCTION: The common peroneal nerve is major lateral division of the sciatic nerve supplies lateral and anterior compartment of leg, when injured may leads to debilitating conditions such as foot drop and sensory loss or numbness in its supplied area. Common peroneal nerve's position subjects it to nerve injuries at two places one behind the knee joint where the nerve is superficial and other being the course of nerve through the fibular tunnel where its being tugged between musculo-aponeurotic fibers of peroneus longus muscle. Nerve injuries to common peroneal nerve has been attributed to several factors depending upon its anatomical position such as this may be due to sudden weight loss, prolonged sitting in squatting position, meniscus injuries in athletes or whether it is any surgical procedures involving the upper part of tibia and fibula. MATERIAL & METHODS: In present study we examine 70 lower limbs equally of right and left sides, the course, branching pattern and other reference point distances were measured with the help of metallic scale and dissections were photograph. RESULT: In 60% cases nerve separate from sciatic at the apex of popliteal fossa and in 80% cases it passes through the groove and then in about 70% specimen it passes through fibular tunnel, where it remains on an average 1.33 cm below the fibular head. The average distance of the nerve division was found 2.73 cm and just below that at a distance of 4.29 cm the nerve is in close contact with the bone. CONCLUSION: In present study we have observed average 7 muscular branches with variable origin from the common peroneal nerve in fibular tunnel which are likely to be damaged during surgical incision at this site.

Screening power of STIR muscle MRI in Critical illness myo-neuropathy and GBS in the ICU

Introduction; Critical illness myo-neuropathy [CIMN] or ICU acquired weakness [CIMN] is a common cause of weakness in ICU patients. It is diagnosed by clinical features, nerve conduction studies and muscle/nerve biopsies. Methods; The MRI muscle STIR images of 7 patients with suspected CIMN and 7 GBS patients were reviewed. Results; All 7 patients with CIMN showed diffuse muscle edema, predominating in the lower limbs. Only one patient with GBS showed abnormal MRI changes (14%) and MRI was normal in 86%. The sensitivity of MRI to detect CIMN was 100%, whereas the specificity was 85.7%. Thus, the positive predictive value of MRI in this situation was 87.5% and the negative predictive value was 100%. Conclusions; Muscle STIR imaging may help to differentiate between CIMN and GBS and can modify the diagnostic algorithm of CIMN.