Effect of muscle length on surface EMG wave forms in isometric contractions

Summary To elucidate the influence of muscle length on surface EMG wave form, comparisons were made of surface EMGs of the biceps and triceps brachii muscles during isometric contractions at different muscle lengths. Muscle lengths were altered by setting the elbow joint angle at several intervals between the limits of extension and flexion. The intensity of the isometric contractions was 25% of maximum voluntary contraction at the individual joint angles. Slowing was obvious in the EMG wave forms of biceps as muscle length increased. The so-called Piper rhythm appeared when the muscle was more than moderately lengthened. The slowing trend with muscle lengthening, though less marked, was also seen in triceps. Zero-cross analysis revealed quasi-linear relationships between muscle length and slowing. Frequency analysis confirmed the development of Piper rhythm. An attempt was made to interpret the slowing associated with muscle lengthening in terms of the propagation of myoelectric signals in muscle fibers. Given the effect of muscle length on EMG wave forms, a careful control of joint angle may be required in assessing local muscle fatigue when using EMG spectral indices.     

Spermatozoal nuclear determinants of reproductive outcome: implications for ART

A male factor is implicated in more than 50% of couples treated with IVF. However, neither the routine testing of male fertility potential nor its treatment address the specific mechanisms by which spermatozoal factors may impact upon reproductive outcome. An important function of spermatozoa is to deliver the paternal genome to the oocyte. Recently, a number of acquired spermatozoal nuclear factors that may have implications on reproductive outcome have been described. These include non-specific DNA strand breaks, numerical abnormalities in spermatozoal chromosome content, Y chromosome microdeletions and alterations in the epigenetic regulation of paternal genome. The exact mechanisms by which these factors affect reproduction are unknown and their implications for assisted reproduction technology outcome need to be further investigated. These recent findings point to the need for novel and more personalized approaches to test and treat male factor infertility.     

Melatonin secretion in the Mashona mole-rat, Cryptomys darlingi--influence of light on rhythmicity

The hormone melatonin is synthesised and secreted from the pineal gland in darkness and triggers the daily and seasonal timing of various physiological and behavioural processes. The Mashona mole-rat, Cryptomys darlingi, lives in subterranean burrows that are completely sealed and is therefore rarely, if ever, exposed to light under natural conditions. Hence, this species is of particular interest for studies on rhythms of melatonin secretion. We investigated how plasma melatonin concentrations of the Mashona mole-rat responded to exposure to a long-term standard photoperiod of 12 h light, 12 h dark (12:12 LD), constant light (LL) and constant dark (DD). In addition, we examined whether plasma melatonin concentration was coupled to locomotor activity. Mashona mole-rats displayed rhythms of plasma melatonin concentration that appeared entrained to the standard LD photoperiod, suggesting that the mole-rat is capable of perceiving and entraining to this photic zeitgeber. Furthermore, under chronic constant lighting conditions (DD, LL), circadian rhythms in plasma melatonin concentration were observed, suggesting the possible existence of an endogenous rhythm. Light suppressed melatonin secretion, but constant light did not abolish the rhythm of plasma melatonin concentration. Between active and non-active animals, no difference in plasma melatonin concentration was found for any of the sequential photoperiods (LD1 DD, LD2, LL), tentatively suggesting that the rhythm of melatonin secretion is uncoupled from that of locomotor activity.     

Reproductive risk factors in unilateral and bilateral renal agenesis

ABSTRACT  Renal agenesis (RA) appears to be a multifactorial condition with combined genetic and environmental influences. We performed a retrospective case-control study of reproductive history of 26 isolated RA live births cases referred to Sicilian Registry of Congenital Malformations. A statistical significant association for birth weight if we considered all RA together and for bilateral RA alone, an increasing risk for maternal age only in the bilateral RA subgroup and a male predominance both for unilateral and bilateral RA was found. Our results show that some reproductive risk factors may be associated with RA, moreover differences found between subgroups indicate that some risk factors may be different in unilateral and bilateral RA. The association between reproductive risk factors and RA may reflect pathogenetic interaction between genetic and environmental factors. Nevertheless further studies are needed to clarify these associations and to explore the role of perinatal factors in the etiology of renal agenesis. In fact if prenatal or perinatal risk factors are in a causal chain influencing the risk for developing RA, then these data could have important implications in the prevention or treatment of this condition.     

脑红蛋白在成年男性生殖系统的表达及意义

目的:探讨脑红蛋白(neuroglobin,Ngb)在成年男性生殖系统的表达及其意义。方法:用免疫组织化学SP法观测Ngb在成人男性生殖系统的表达、分布与定位。结果:Ngb在生殖系统内神经节细胞、睾丸间质细胞有较强表达,在睾丸支持细胞、生精细胞、附睾管腔上皮、前列腺腺上皮及精囊黏膜上皮呈弱阳性表达。结论:Ngb在男性生殖系统中分布广泛,其功能值得研究。     

Biological balance of sodium and potassium

Summary The rhythm of renal sodium and potassium excretion was measured in 4-h-intervals in 12 subjects. Each person exhibited clear circadian variations of each variable with a maximum between 8 a.m. and 4 p.m. In each subject and for both circadian rhythms the oscillation mean was correlated to the range of oscillation (amplitude).Increase in sodium or potassium excretion during 1 day resulted in an increase of oscillation range. The oscillation means of sodium and potassium periodicity did not correlate.The properties of biological control systems with oscillating correcting variables are comparable to those of technical control systems. The significance of circadian rhythm for the control of electrolyte balance is indicated.     

Control of feeding rhythm in the terrestrial slug Incilaria bilineata

A modulatory neuron of feeding rhythm was newly identified in the buccal ganglia of the isolated central nervous system (CNS) of the terrestrial slug Incilaria bilineata. This neuron was termed the “feeding rhythm modulator” (FRM). Its morphological and electrical properties were compared with those of the MGC (metacerebral giant cell, a cerebral modulatory neuron of feeding rhythm). There was no direct connection between FRM and MGC. In order to investigate the control mechanism of the buccal central pattern generator, feeding rhythm was observed by varying the activities of MGC and FRM simultaneously. At a lower level of activity of MGC, feeding rhythm was not only sensitive to the activity of MGC but also to that of FRM. As the level of activity of MGC increased, feeding rhythm was exclusively controlled by the activity of MGC, and became unaffected by the activity of FRM. This indicates that cerebral neurons such as MGC primarily control feeding rhythm and modulate the contribution of FRM in a hierarchical manner.     

Fibroids, infertility and pregnancy wastage

Uterine fibroids are often found in women of reproductive age. Different types of fibroids may affect reproductive outcome to a different extent, with submucous, intramural and subserosal fibroids being (in decreasing order of importance) a cause of infertility and pregnancy wastage. Fibroids may also produce a number of complications during pregnancy. Women who are scheduled for assisted conception should be advised to have submucous and possibly intramural fibroids removed prior to IVF. Large fibroids (>5 cm), wherever their location, should be considered individually, with the reproductive history being an important consideration. Miscarriage rates are significantly reduced following myomectomy. Open myomectomy should be the route of choice when there are large subserosal or intramural fibroids, multiple fibroids or entry into the uterine cavity is to be expected. Proper assessment of the benefits and risks of surgery for individual patients should be carefully considered before offering a procedure.     

Certain characteristics of myocardial contractility of isovolumic dog heart at randomly variable heart rhythm

Summary The relationship heart rate-left ventricular pressure was investigated in the isolated canine heart perfused with constant pressure at different preloads. Rhythmical stimulation was performed with constant stimulus interval duration and with stimulus intervals randomly changed near the average value (150–200 stimuli in series).Correlation and dispersion function analysis show that rhythm dispersion had a negative inotropic effect which was independent of the preload of the ventricle in the range of 120–180 beat/min, but this dependence occurred with low rates of stimulation.This method is proposed for the assessment of contractility under conditions of heart rate variations (physiological and pathological arrhythmias).     

Brain–Gut–Microbiome Interactions and Intermittent Fasting in Obesity

The obesity epidemic and its metabolic consequences are a major public health problem both in the USA and globally. While the underlying causes are multifactorial, dysregulations within the brain–gut–microbiome (BGM) system play a central role. Normal eating behavior is coordinated by the tightly regulated balance between intestinal, extraintestinal and central homeostatic and hedonic mechanisms, resulting in stable body weight. The ubiquitous availability and marketing of inexpensive, highly palatable and calorie-dense food has played a crucial role in shifting this balance towards hedonic eating through both central (disruptions in dopaminergic signaling) and intestinal (vagal afferent function, metabolic toxemia, systemic immune activation, changes to gut microbiome and metabolome) mechanisms. The balance between homeostatic and hedonic eating behaviors is not only influenced by the amount and composition of the diet, but also by the timing and rhythmicity of food ingestion. Circadian rhythmicity affects both eating behavior and multiple gut functions, as well as the composition and interactions of the microbiome with the gut. Profound preclinical effects of intermittent fasting and time restricted eating on the gut microbiome and on host metabolism, mostly demonstrated in animal models and in a limited number of controlled human trials, have been reported. In this Review, we will discuss the effects of time-restricted eating on the BGM and review the promising effects of this eating pattern in obesity treatment.