Sensory supplementation system based on electrotactile tongue biofeedback of head position for balance control

The present study aimed at investigating the effects of an artificial head position-based tongue-placed electrotactile biofeedback on postural control during quiet standing under different somatosensory conditions from the support surface. Eight young healthy adults were asked to stand as immobile as possible with their eyes closed on two Firm and Foam support surface conditions executed in two conditions of No-biofeedback and Biofeedback. In the Foam condition, a 6-cm thick foam support surface was placed under the subjects’ feet to alter the quality and/or quantity of somatosensory information at the plantar sole and the ankle. The underlying principle of the biofeedback consisted of providing supplementary information about the head orientation with respect to gravitational vertical through electrical stimulation of the tongue. Centre of foot pressure (CoP) displacements were recorded using a force platform. Larger CoP displacements were observed in the Foam than Firm conditions in the two conditions of No-biofeedback and Biofeedback. Interestingly, this destabilizing effect was less accentuated in the Biofeedback than No-biofeedback condition. In accordance with the sensory re-weighting hypothesis for balance control, the present findings evidence that the availability of the central nervous system to integrate an artificial head orientation information delivered through electrical stimulation of the tongue to limit the postural perturbation induced by alteration of somatosensory input from the support surface.     

A role of the histaminergic system for the control of feeding by orexigenic peptides

A considerable number of neuropeptides are involved in the hypothalamic regulation of feeding behavior. We previously reported that leptin, the ob gene product, expressed its anorectic effect though the histaminergic system via histamine H(1) receptors. However, the interactions among the orexigenic neuropeptides, such as orexin-A, neuropeptide Y (NPY), and ghrelin, and the histaminergic system have not yet been clarified. In this study, we investigated the effect of the neuropeptides on the hypothalamic histamine release in rats, and on food intake and locomotor activity in H(1)-receptor knockout (H1R-KO) mice. Orexin-A increased the histamine release and locomotor activity, but not food intake, suggesting that the histaminergic system participates in arousal rather than feeding by orexin-A. NPY also increased histamine release, but its effect was not immediate. NPY-injected H1R-KO mice consumed more food than the wild-type mice; thus, the histaminergic system may act as a feedback factor downstream of NPY. Ghrelin did not affect histamine release, and it increased food intake, even in H1R-KO mice. Thus, ghrelin expresses its action in a histamine-independent manner.     

Energy balance and food intake: the role of PPARgamma gene polymorphisms

Mechanisms regulating energy balance involve complex interactions between genetic, environmental and behavioural (learnt and intrinsic) factors. Genotype may drive the partitioning of energy metabolism and predispose to site-specific adiposity, culminating in a state of energy imbalance. One candidate gene with a direct link to adiposity is the peroxisome proliferator-activated receptor gamma (PPARG) gene. PPARG is a cell nuclear receptor expressed almost exclusively in adipose tissue that regulates adipocyte differentiation, lipid metabolism and insulin sensitivity. PPARgamma appears to be a key regulator of energy balance, with polymorphisms on the PPARG gene linked to obesity and effects on body composition. Our research has confirmed an association between the pro12ala allele and reduced incidence of obesity in pre-pubertal children and there are strong associations between genetic variation at the PPARG locus and percentage body fat. Moreover, our evidence suggests that PPARG C-681G and pro12ala polymorphisms display opposing effects in terms of growth phenotype, with pro12Ala associated with deficient energy utilisation, leading to reduced growth and the G-681 variant associated with accelerated growth compared with wildtypes. Common differences in this gene have also been associated with variations in body weight in response to dietary macronutrients. Preliminary evidence suggests that PPARG variants may even be involved in the control of short term energy compensation. Taken together these data suggest that the role of PPARG is varied and complex, influencing fat deposition and growth velocity early in life, with potential impact in the control of energy intake and appetite regulation, and could provide a key target for future research and anti-obesity agents.     

The role of GABAergic system on the inhibitory effect of ghrelin on food intake in neonatal chicks

Ghrelin is a gut-brain peptide that has a stimulatory effect on food intake in mammals. In contrast, this peptide decreases food intake in neonatal chicks when injected intracerebroventricularly (ICV). In mammals, neuropeptide Y (NPY) mediates the orexigenic effect of ghrelin whereas in chicks it appears that corticotrophin releasing factor (CRF) is partially involved in the inhibitory effect of ghrelin on food intake. Gamma aminobutyric acid (GABA) has a stimulatory effect on food intake in mammals and birds. In this study we investigated whether the anorectic effect of ghrelin is mediated by the GABAergic system. In Experiment 1, 3 h-fasted chicks were given an ICV injection of chicken ghrelin and picrotoxin, a GABA_A receptors antagonist. Picrotoxin decreased food intake compared to the control chicks indicating a stimulatory effect of GABA_A receptors on food intake. However, picrotoxin did not alter the inhibitory effect of ghrelin on food intake. In Experiment 2, THIP hydrochloride, a GABA_A receptor agonist, was used in place of picrotoxin. THIP hydrochloride appeared to partially attenuate the decrease in food intake induced by ghrelin at 30 min postinjection. In Experiment 3, the effect of ICV injection of chicken ghrelin on gene expression of glutamate decarboxylase (GAD)₁ and GAD₂, GABA synthesis enzymes in the brain stem including hypothalamus, was investigated. The ICV injection of chicken ghrelin significantly reduced GAD₂ gene expression. These findings suggest that ghrelin may decrease food intake in neonatal chicks by reducing GABA synthesis and thereby GABA release within brain feeding centers.     

The effect of ghrelin on water intake during dipsogenic conditions

Ghrelin has been studied extensively in the context of food intake and energy homeostasis, but less is known about its role in other ingestive behaviors. The present studies investigated the effects of this orexigenic peptide on both food and water intake during dipsogenic conditions. Specifically, animals were exposed to one of five dipsetic stimuli: (1) 24-h water deprivation, (2) replacement of drinking water with 2.5% NaCl, (3) peripheral administration of hypertonic saline, (4) ICV injection of angiotensin II (AngII), or (5) the combination of peripheral hypertonic saline and central AngII. Animals then were given an ICV injection of ghrelin (0.5  µg) or vehicle, and subsequent food and water intakes were measured. Ghrelin reliably increased food intake under each stimulus condition. Ghrelin also affected water intake, but with less consistency across the conditions. Specifically, ghrelin attenuated water intake stimulated by acute injection of AngII or hypertonic saline, but failed to affect drinking in the other three stimulus conditions. Investigation of the temporal pattern of food and water intakes in three of these dipsogenic conditions failed to support a role of different intake patterns in the observed differences in water intake by ghrelin-treated rats. Although the effect of ghrelin on water intake was not present in every dipsogenic condition, these data provide evidence that the actions of ghrelin are not limited to food intake, but can also include alterations in water intake.     

SKF 83566 attenuates the effects of ghrelin on performance in the object location memory task

Increasing research implicates ghrelin, a metabolic signaling peptide, in memory processes including acquisition, consolidation, and retention. The present study investigated the effects of ghrelin on spatial memory acquisition by utilizing the object location memory task paradigm. Given the co-expression of ghrelin and dopamine D₁ receptors within hippocampal neurons, we examined a potential interaction between these two systems on memory performance. When injected into the dorsal third ventricle (D3V) of male Sprague-Dawley rats, proximal to hippocampal tissue, ghrelin (500 pmol) increased the amount of time spent with objects in novel locations. This effect was completely reversed by the D₁ antagonist SKF 83566 (100 μg/kg IP), although when administered alone, the antagonist had no effect on task performance (10-100 μg/kg). We also examined the feeding effects of D3V ghrelin and found that the peptide reliably increased food intake (500 pmol) but that this effect was not blocked by SKF 83566 (100 μg/kg). When given alone, SKF 83566 did not alter food intake (10-100 μg/kg). Our findings indicate that, in addition to an orexigenic effect, ghrelin improves acquisition of spatial location memories. Furthermore, D₁ receptor activation is necessary for ghrelin to improve the encoding of spatial memories but does not impact the increase in food intake elicited by the peptide.     

A versatile remote control system for functional expression of bacterial virulence genes based on the tetA promoter

The expression of bacterial virulence factors is controlled in response to host or environmental factors and most virulence genes are not expressed under laboratory conditions. Investigations of molecular structures and cellular functions of bacterial virulence factors demand systems for experimentally controlled expression. We describe a simple and robust system that is based on the tetA promoter and the cognate repressor TetR. Expression under control of P_tetA can be induced by non-antibiotic derivatives of tetracycline such as anhydrotetracycline (AHT). Tet-on expression cassettes can be used to replace native promoters of chromosomal genes or operons of interest. Tet-on plasmids allow episomal expression in homologous or heterologous host organisms. We demonstrate the application of Tet-on systems for the controlled induction of flagella assembly and motility, and for surface expression of adhesins of the chaperone/usher family of enteropathogenic Escherichia coli and autotransporter adhesins of Yersinia enterocolitica in Salmonella enterica and E. coli. Since inducer AHT can easily cross bacterial envelopes and mammalian cell membranes, the system can also be applied to control virulence genes in intracellular bacteria. We demonstrate the controlled synthesis, translocation and function of effector proteins of the type III secretion system of intracellular S. enterica.     

基于增强现实技术的可视化实时引导系统在股骨头坏死髓芯减压术中定位的初步临床试验*

目的 探讨基于增强现实（AR）技术的可视化实时引导系统用于股骨头坏死微创介入手术定位的可行性、精准度和临床优势。方法 试验组纳入2021年1月至2021年3月于本院诊治的9例（10髋）股骨头缺血性坏死患者,在基于AR技术的可视化实时引导系统的辅助下行股骨头坏死髓芯减压术定位穿刺,记录术中定位时长、透视次数,术后利用影像学资料评价系统精度;按照配对原则选择2019年1月至2021年3月行传统股骨头坏死髓芯减压术的患者8例（10髋）作为对照组。对比两组定位时长、透视次数,评估该系统的有效性。结果 试验组和对照组的平均定位时长分别为（10.1±1.9）min和（19.1±2.5）min,两者比较差异有统计学意义（P<0.05）。试验组和对照组的平均透视次数分别为（5.5±1.3）次和（14.8±12.1）次,两者比较差异有统计学意义（P<0.05）。试验组平均距离定位误差（5.0±5.2）mm,平均角度定位误差（6.4±2.5）°。两组中均无不良事件发生。结论 基于AR技术的可视化实时引导系统相比于传统手术方式,在保证穿刺精度的同时极大程度地减少了定位时长和透视次数。