Effects of plantar foot sensitivity manipulation on postural control of young adult and elderly / Efeitos da manipulação da sensibilidade plantar sobre o controle da postura ereta em adultos jovens e idosos

ABSTRACT Introduction: Subjects with sensorial losses present balance deficits. Although such condition is often observed among elderly, there is discussion concerning the dependence on sensorial information for body sway control in the elderly without sensorial losses. Purpose: We investigated the effects of foot sensitivity manipulation on postural control during upright standing in young adults and independent elderly (n = 19/group). Methods: Plantar sensitivity was evaluated by esthesiometry, and speed of center of pressure shift data during upright posture were evaluated for each foot using a baropodometer while the subjects were standing with eyes open or closed. The young adult group was evaluated for center of pressure in normal conditions and after plantar sensitivity disturbance, by immersing their feet in water and ice. Results: Young adults did not show alterations in their center of pressure after sensorial perturbation and presented, even under sensorial perturbation, better postural control than elderly subjects. The elderly showed lower foot sensitivity and greater center of pressure oscillation than young adults. Conclusion: Elderly subjects seem to rely more on foot sensitivity for control of body sway than young adults. In the elderly, a clinical intervention to improve foot sensitivity may help in upright posture maintenance.

RESUMO Introdução: Pessoas com perdas sensoriais apresentam déficits de equilíbrio. Embora esse quadro seja comum em idosos, ainda se discute o quanto idosos sem doenças que afetam as vias sensoriais dependem dessa informação para controlar oscilações corporais durante o controle da postura. Objetivo: Investigar os efeitos da perturbação da sensibilidade plantar sobre o controle da postura ereta em adultos jovens e idosos independentes (n = 19/grupo). Métodos: A sensibilidade plantar foi avaliada com estesiômetro e dados de velocidade e deslocamento do centro de pressão durante a postura de pé foram avaliados para cada pé com um baropodômetro, em condições de olhos abertos e fechados. O grupo de adultos jovens foi avaliado quanto ao centro de pressão nas condições normal e pós-perturbação da sensibilidade plantar, pela imersão dos pés em água e gelo. Resultados: Adultos não apresentaram alterações no centro de pressão em resposta à perturbação sensorial e tiveram, mesmo na condição de perturbação sensorial, melhor controle postural do que idosos. Idosos apresentaram menor sensibilidade plantar e maior oscilação do centro de pressão do que os adultos jovens. Conclusão: Idosos pareceram depender mais da sensibilidade plantar para manter o controle postural do que adultos jovens. Em idosos, intervenções clínicas que melhorem a sensibilidade plantar podem auxiliar na tarefa de manter a postura de pé.

Development of a new haptic perception instrument: a pilot study / Desenvolvimento de um novo instrumento de avaliação da percepção háptica: um estudo piloto

ABSTRACT Objective Hand sensory tests do not consider distinct physiological receptors, nor detect normal range variations concerning developmental or pathological changes. We developed an instrument with a set of tests with timing and scoring for assessing haptic perception, which is the interaction between sensory and motor systems, in surfaces exploration, by moving hands. Method Firstly, group meetings were set for test/manual conception and materials testing. The test/manual were submitted to 30 reviewers in 3 stages (10 reviewers on each stage). Results The Hand Haptic Perception Instrument (HHPI) evaluates hand sensorimotor performance on six domains: depression, elevation, texture, compressibility, weight (barognosis) and form perception. Each domain requires specific materials. Score ranges from 0 to 57, being 0 the worst rating. Conclusion This methodological process allowed the development of six domains and instructions to assess haptic perception. This version of HHPI is a pilot model. Further studies will determine reliability and normality ranges.

RESUMO Objetivo Testes de sensibilidade manual não consideram receptores fisiológicos distintos, tampouco variações do desenvolvimento normal ou patológico. Desenvolvemos um instrumento, com pontuação e tempo de desempenho, para avaliar percepção háptica, que é a interação sensório-motora na exploração de superfícies, pelo movimento das mãos. Método Reuniões de grupo foram estabelecidas para desenvolver os testes/ manual e testar materiais. O instrumento e seu manual foram submetidos a 30 revisores, em 3 estágios (com 10 revisores em cada estágio). Resultados O instrumento de avaliação da percepção háptica manual (IAPHM) avalia o desempenho sensório-motor da mão em seis domínios: depressão, elevação, textura, compressibilidade, peso (barognosia) e percepção de forma. Cada domínio requer materiais específicos. A pontuação vai de 0 a 57, sendo 0 a pior pontuação. Conclusão Esse método permitiu o desenvolvimento do instrumento para avaliar percepção háptica. Essa versão do IAPHM é um modelo piloto. Estudos futuros determinarão confiabilidade e variações de normalidade.

Oseopercepción: una puesta al día / Osseoperception: an update

La incorporación de implantes dentales al Sistema Estomatognático genera muchos cuestionamientos, entre ellos: ¿Cómo se explica que el paciente “sienta” a través de estos sistemas de anclaje?; ¿Por qué el paciente dice que mastica mejor que con las prótesis mucosoportadas?;¿Por qué a pesar de haber perdido dos componentes fisiológicos esenciales (dientes y periodonto) no se aprecian clínicamente importantes problemas dentro del sistema?; ¿Qué reordenamientos del sistema nervioso determinan la regulación motora luego de rehabilitado con estas técnicas? Es probable que las respuestas surjan a través del conocimiento de una nueva modalidad sensorial descriptacomo oseopercepción, la cual implica un reordenamiento de las áreas sensitivas y motoras de la corteza cerebral (neuroplasticidad).

Many questions arise from the introduction of dental implants into the stomatognathic system, for example: How can patients “feel” through these anchorage structures? Why does the patient feel that his mastication is improved with respect to the classic complete dentures? Why there are not remarkable alterations in the function of the stomatognathic system despite the loss of two essential componentsof this system? What rearrangements of the nervous system take place after the placement of dental implants that control the motor regulation of the stomatognathic system? Probably, the answer to these questions may come from the study of a new sensorymodality known as osseoperception, which involves a rearrangement of sensory and motor areas of the brain cortex (neuroplasticity).

Control of respiration in fish, amphibians and reptiles

Fish and amphibians utilise a suction/force pump to ventilate gills or lungs, with the respiratory muscles innervated by cranial nerves, while reptiles have a thoracic, aspiratory pump innervated by spinal nerves. However, fish can recruit a hypobranchial pump for active jaw occlusion during hypoxia, using feeding muscles innervated by anterior spinal nerves. This same pump is used to ventilate the air-breathing organ in air-breathing fishes. Some reptiles retain a buccal force pump for use during hypoxia or exercise. All vertebrates have respiratory rhythm generators (RRG) located in the brainstem. In cyclostomes and possibly jawed fishes, this may comprise elements of the trigeminal nucleus, though in the latter group RRG neurons have been located in the reticular formation. In air-breathing fishes and amphibians, there may be separate RRG for gill and lung ventilation. There is some evidence for multiple RRG in reptiles. Both amphibians and reptiles show episodic breathing patterns that may be centrally generated, though they do respond to changes in oxygen supply. Fish and larval amphibians have chemoreceptors sensitive to oxygen partial pressure located on the gills. Hypoxia induces increased ventilation and a reflex bradycardia and may trigger aquatic surface respiration or air-breathing, though these latter activities also respond to behavioural cues. Adult amphibians and reptiles have peripheral chemoreceptors located on the carotid arteries and central chemoreceptors sensitive to blood carbon dioxide levels. Lung perfusion may be regulated by cardiac shunting and lung ventilation stimulates lung stretch receptors.

The influence of gender and bruxism on human minimum interdental threshold ability

OBJECTIVE: To evaluate the influence of gender and bruxism on the ability to discriminate minimum interdental threshold. MATERIAL AND METHODS: One hundred and fifteen individuals, representing both genders, bruxers and non-bruxers, with a mean age of 23.64 years, were selected for this study. For group allocation, every individual was subjected to a specific physical examination to detect bruxism (performed by three different examiners). Evaluation of the ability to discriminate minimum interdental threshold was performed using industrialized 0.010 mm-, 0.024 mm-, 0.030 mm-, 0.050 mm-, 0.080 mm- and 0.094 mm-thick aluminum foils that were placed between upper and lower premolars. Data were analyzed statistically by multiple linear regression analysis at 5% significance level. RESULTS: Neither gender nor bruxism influenced the ability to discriminate minimum interdental threshold (p>0.05). CONCLUSIONS: Gender and the presence of bruxism do not play a role in the minimum interdental threshold.

Streptozotocin-induced mechanical hypernociception is not dependent on hyperglycemia

Since streptozotocin (STZ)-induced diabetes is a widely used model of painful diabetic neuropathy, the aim of the present study was to design a rational protocol to investigate whether the development of mechanical hypernociception induced by STZ depends exclusively on hyperglycemia. Male Wistar rats (180-200 g; N = 6-7 per group) received a single intravenous injection of STZ at three different doses (10, 20, or 40 mg/kg). Only the higher dose (40 mg/kg) induced a significant increase in blood glucose levels, glucose tolerance and deficiency in weight gain. However, all STZ-treated rats (hyperglycemic or not) developed persistent (for at least 20 days) and indistinguishable bilateral mechanical hypernociception that was not prevented by daily insulin treatment (2 IU twice a day, sc). Systemic morphine (2 mg/kg) but not local (intraplantar) morphine treatment (8 µg/paw) significantly inhibited the mechanical hypernociception induced by STZ (10 or 40 mg/kg). In addition, intraplantar injection of STZ at doses that did not cause hyperglycemia (30, 100 or 300 µg/paw) induced ipsilateral mechanical hypernociception for at least 8 h that was inhibited by local and systemic morphine treatment (8 µg/paw or 2 mg/kg, respectively), but not by dexamethasone (1 mg/kg, sc). The results of this study demonstrate that systemic administration of STZ induces mechanical hypernociception that does not depend on hyperglycemia and intraplantar STZ induces mechanical sensitization of primary sensory neurons responsive to local morphine treatment.

Training-related changes in the R-R interval at the onset of passive movements in humans

The aim of the present study was to determine whether training-related alterations in muscle mechanoreflex activation affect cardiac vagal withdrawal at the onset of exercise. Eighteen male volunteers divided into 9 controls (26 ± 1.9 years) and 9 racket players (25 ± 1.9 years) performed 10 s of voluntary and passive movement characterized by the wrist flexion of their dominant and non-dominant limbs. The respiratory cycle was divided into four phases and the phase 4 R-R interval was measured before and immediately following the initiation of either voluntary or passive movement. At the onset of voluntary exercise, the decrease in R-R interval was similar between dominant and non-dominant forearms in both controls (166 ± 20 vs 180 ± 34 ms, respectively; P > 0.05) and racket players (202 ± 29 vs 201 ± 31 ms, respectively; P > 0.05). Following passive movement, the non-dominant forearm of racket players elicited greater changes than the dominant forearm (129 ± 30 vs 77 ± 17 ms; P < 0.05), as well as both the dominant (54 ± 20 ms; P < 0.05) and non-dominant (59 ± 14 ms; P < 0.05) forearms of control subjects. In contrast, changes in R-R interval elicited by the racket players' dominant forearm were similar to that observed in the control group, indicating that changes in R-R interval at the onset of passive exercise were not attenuated in the dominant forearm of racket players. In summary, cardiac vagal withdrawal induced by muscle mechanoreflex stimulation is well-maintained, despite long-term exposure to training.

Sistema sensório-motor articular: revisão de literatura / Joint sensorimotor system: a literature review

Tradicionalmente, a estabilidade articular é considerada como a perfeita congruência entre ossos durante o movimento, sendo que muitas vezes os componentes atribuídos para esta estabilidade se resumem aos ligamentos e músculos envolvidos na articulação...

Joint stability is traditionally defined as the perfect congruence among bones during movement; the components of such stability are often limited to related ligaments and muscles. Although these structures are the greatest joint stabilizers, motor-sensory integrity is fundamental for an efficient joint stability...

Understanding the mechanisms of lung mechanical stress

Physical forces affect both the function and phenotype of cells in the lung. Bronchial, alveolar, and other parenchymal cells, as well as fibroblasts and macrophages, are normally subjected to a variety of passive and active mechanical forces associated with lung inflation and vascular perfusion as a result of the dynamic nature of lung function. These forces include changes in stress (force per unit area) or strain (any forced change in length in relation to the initial length) and shear stress (the stress component parallel to a given surface). The responses of cells to mechanical forces are the result of the cell's ability to sense and transduce these stimuli into intracellular signaling pathways able to communicate the information to its interior. This review will focus on the modulation of intracellular pathways by lung mechanical forces and the intercellular signaling. A better understanding of the mechanisms by which lung cells transduce physical forces into biochemical and biological signals is of key importance for identifying targets for the treatment and prevention of physical force-related disorders.

Cases of Swallow Syncope Induced by the Activation of Mechanorecepters in the Lower Esophagus

Swallowing is a rare cause of neurally mediated syncope. The mechanism of swallow syncope that contributes to hypotension, bradycardia, or to both is complex. A 59-year-old man had experienced a recurrent loss of consciousness during swallowing of carbonated beverages or sticky foods. Another 59-year-old man had complained of intermittent syncope just after eating foods. These two patients had no significant structural or functional abnormalities in the esophagus or heart. Both cases showed bradycardia when the lower esophagus was stretched by balloon inflation. The activation of mechanoreceptors in the lower esophagus can be regarded as an initiating factor of these cardioinhibitions. The patients were treated with permanent pacemaker implantation and instructed to change eating habits, respectively.

The central projection of cephalic mechanosensory axons in the haematophagous bug Triatoma infestans

The projections of mechanosensory hairs located on the dorsal and lateral head of the adult haematophagous bug Triatoma infestans were analyzed by means of cobalt filling. Axons run into the anterior and posterior tegumentary nerve and project through the brain to the ventral nerve cord. The fibres are small in diameter and run as a fascicle. Some branches run into suboesophageal and prothoracic centres; others run as far as to the mesothoracic ganglion. These sensory projections resemble that of wind-sensitive head hairs of the locust. The functional role of this sensory system in this species is discussed.

Mecanorreceptores cardíacos / Cardiac mechanoreceptors

Utilizou-se a noradrenalina na dose padräo de 2 ug/Kg, medindo-se o fluxo na artéria femoral antes e após o estímulo. A injeçäo foi feita em diversos níveis da aorta, intracardíaca e na veia axilar. Para estudar a dependência do fenômeno com as vias nervosas, estimularam-se cäes com os nervos femoral e ciático seccionados, com desnervaçäo dos seios carotídeos e aórtico e com os vagos seccionados bilateralmente. Foi possível observar que: 1 - O aumento da atividade cardíaca que se acompanha de aumento da contratilidade é estímulo eficaz para desencadear o aumento do fluxo na artéria femoral. O aumento da contratilidade cardíaca e a diminuiçäo da resistência periférica säo proporcionais à dose de noradrenalina injetada (dentro dos limites de 1 a 3 ug). 2- No cäo com uma pata posterior submetida à secçäo dos nervos femoral ciático, a injeçäo de noradrenalina causa diminuiçäo da resistência vascular na pata normal, simultaneamente com o aumento da resistência na pata desnervada. Essa observaçäo demonstra ser esse fenômeno um reflexo. 3- A secçäo dos seios carotídeos e aórticos quase näo influencia essa resposta reflexa. 4- A injeçäo de noradrenalina na artéria femoral e em diversas posiçöes da aorta näo causa diminuiçäo da resistência periférica. A injeçäo endovenosa no bulbo aórtico e intracardíaca (ventrículo esquerdo) sempre leva à vasodilataçäo na regiäo estudada. 5- A secçäo vagal deprime acentuadamente a resposta, demonstrando ser essa a principal via nervosa responsável pelo reflexo

Suppression of plasma aldosterone during stimulation of cardiopulmonary mechanoreceptors in man

Con el objeto de analizar la participación de los mecanorreceptores cardiopulmonares en la secreción de la aldosterona, se estudiaron 10 voluntarios varones mediante la utilización de un traje que, al ser llenado con agua y estando el sujeto en inclinación de 45§, ejerce una presión positiva sobre los miembros inferiores con traspaso de volumen sanguíneo de éstos al compartimiento cardiopulmonar. En estas condiciones se comprobó una caída significativa de la aldosterona plasmática a los 60 minutos, de 223ñ23pg/ml a 190ñ26pg/ml (p<0,01), coincidiendo con un descenso de la actividad renínica plasmática a los 30 minutos de 3,51ñ1,48mg/ml/h a 1,8ñ0,89mg/ml/h (p<0,05) y un incremento de la radioactividad de fin de diástole de ventrículo derecho de 9500ñ1150cpm a 11685ñ2600cpm (p<0,01) y de la radioactividad de fin de sístole ventricular derecha de 5865ñ946cpm a 7758ñ1050cpm (p<0,05), medida con un ventriculograma radioisotópico. Al suspender la presión sobre los miembros inferiores, la aldosterona y la actividad renínica plasmática retornaron inmediatamente a los niveles basales, luego de registrarse un descenso de la radioactividad de fin de diástole y fin de sístole del ventrículo derecho. Se concluye que los mecanorreceptores cardiopulmonares participan en la regulación de la aldosterona y el sistema renina-angiotensina

Study of heart rate and blood pressure changes under distension of right and left atrial appendages in dogs.

Fifteen healthy stray dogs of both sexes were employed in the present study. The effect of distension of right and left atrial appendages with normal saline was observed on heart rate and blood pressure under different situations. It has been found that distension of either appendages separately or simultaneously invariably evoked tachycardia without any appreciable change in blood pressure. Increase in heart rate was found to be of a same magnitude with 5 ml normal saline in both the atrial appendages. However, a higher response was obtained with 10 ml normal saline distension in case of right atrial appendage as compared to left one. Increase in the extent of distension causes more significant response, the receptors of which are stimulated and may be allied to stretch receptors. It is contended that tachycardia could be a reflex effect which is abolished by vagotomy. It is further contended that either afferent, efferent or both pathways exist in the vagi.