Karla Mônica Ferraz

Passive stiffness of rat skeletal muscle undernourished during fetal development

OBJECTIVES: The aim of the study was to investigate the effect of fetal undernutrition on the passive mechanical properties of skeletal muscle of weaned and young adult rats. INTRODUCTION: A poor nutrition supply during fetal development affects physiological functions of the fetus. From a mechanical point of view, skeletal muscle can be also characterized by its resistance to passive stretch. METHODS: Male Wistar rats were divided into two groups according to their mothers diet during pregnancy: a control group (mothers fed a 17% protein diet) and an isocaloric low‐protein group (mothers fed a 7.8% protein diet). At birth, all mothers received a standardized meal ad libitum. At the age of 25 and 90 days, the soleus muscle and extensor digitorum longus (EDL) muscles were removed in order to test the passive mechanical properties. A first mechanical test consisted of an incremental stepwise extension test using fast velocity stretching (500 mm/s) enabling us to measure, for each extension stepwise, the dynamic stress (σd) and the steady stress (σs). A second test consisted of a slow velocity stretch in order to calculate normalized stiffness and tangent modulus from the stress–strain relationship. RESULTS: The results for the mechanical properties showed an important increase in passive stiffness in both the soleus and EDL muscles in weaned rat. In contrast, no modification was observed in young adult rats. CONCLUSIONS: The increase in passive stiffness in skeletal muscle of weaned rat submitted to intrauterine undernutrition it is most likely due to changes in muscle passive stiffness.

Postural control assessment in students with normal hearing and sensorineural hearing loss

INTRODUCTION Children with sensorineural hearing loss can present with instabilities in postural control, possibly as a consequence of hypoactivity of their vestibular system due to internal ear injury. OBJECTIVE To assess postural control stability in students with normal hearing (i.e., listeners) and with sensorineural hearing loss, and to compare data between groups, considering gender and age. METHODS This cross-sectional study evaluated the postural control of 96 students, 48 listeners and 48 with sensorineural hearing loss, aged between 7 and 18 years, of both genders, through the Balance Error Scoring Systems scale. This tool assesses postural control in two sensory conditions: stable surface and unstable surface. For statistical data analysis between groups, the Wilcoxon test for paired samples was used. RESULTS Students with hearing loss showed more instability in postural control than those with normal hearing, with significant differences between groups (stable surface, unstable surface) (p<0.001). CONCLUSIONS Students with sensorineural hearing loss showed greater instability in the postural control compared to normal hearing students of the same gender and age.

Early physical activity minimizes the adverse effects of a low-energy diet on growth and development parameters

Abstract Objectives The aim of this study was to evaluate the effect of a low-energy diet on rat dams and physical activity in water during the perinatal period on body weight, somatic growth, and neuromotor development. Methods Rat dams were fed with control or low-energy diets from the third gestational week. At 8 days old the littermates were either involved or not in aquatic physical activity. The groups were initially divided into normocaloric (C) or low-energy (LE) diets. The study included 52 male pups from primiparous Wistar rats. Exercise in water was carried out with the pups from the age of 8 to 52 days. Four experimental groups were formed: inactive control (IC), active control (AC), inactive low-energy (ILE), and active low-energy (ALE). Somatic growth (tail length (TL), lateral-lateral axis of the skull (LLAS), anterior-posterior axis of the skull (APAS), and longitudinal axis (LA)), maturation of reflexes and neuromotor development of pup locomotion were analyzed along with a biochemical profile. Results During lactation the body weight range (%) was lower for ILE compared with IC (38%, P < 0.05), as ALE body weight gain was lower (29%, P < 0.05) compared with AC and bigger (17%, P < 0.05) compared with ILE. At 21st day reduced body weight was observed in LE diet groups (IC = 48.62 ± 1.36 g; AC = 48.30 ± 1.03 g; ILE = 30.49 ± 1.60 g; ALE = 39.38 ± 1.06 g, P < 0.05). Compared with control diet, the LE diet delayed somatic growth of pups from 2nd week to end lactation, but the early physical activity in LE group improved some parameters of somatic growth (TL: IC = 68.87 ± 1.00 mm, AC = 68.80 ± 1.10 mm, ILE = 60.21 ± 1.14 mm, ALE = 64.61 ± 0.55 mm; LA: IC = 113.21 ± 1.73 mm, AC = 113.33 ± 1.37 mm, ILE = 99.40 ± 1.67 mm, ALE = 106.76 ± 0.79 mm; APAS: IC = 37.10 ± 0.32 mm, AC: 37.18 ± 0.23 mm, ILE = 34.11 ± 0.33 mm, ALE = 35.84 ± 0.30 mm; LLAS: IC = 18.71 ± 0.24 mm, AC = 19.00 ± 0.16 mm, ILE = 17.10 ± 0.19 mm, ALE = 17.87 ± 0.11 mm, P < 0.05) and reflex ontogeny. Nevertheless, fewer changes were observed in locomotor activity (P > 0.05). At 60 days old, the food intake and measures of murinometrics did not differ among groups, but they had lower glucose levels ILE (IC = 4.14 ± 0.23 mmol/l, AC = 3.70 ± 0.22 mmol/l, ILE = 3.38 ± 0.20 mmol/l, ALE = 4.17 ± 0.09 mmol/l, P < 0.05). Conclusion Taken together, we suggest that physical activity in water acts as a beneficial factor in LE diets of dams during the perinatal period. Further study is necessary to investigate the role of physical activity for adaptation against adverse nutritional stimuli.

Influence of overweight on the active and the passive fraction of the plantar flexors series elastic component in prepubertal children

The influence of overweight, as a precursor to obesity, was analyzed on the elastic properties of the triceps surae. Based on body mass index (BMI), children (9 years ± 4 mo) were classified as control (CON; n = 23; BMI -1SD>Z score<1SD) or overweight (OW; n = 21, BMI 1SD>Z score<3SD) with regard to reference data from the World Health Organization. Musculotendinous (MT) stiffness of the series elastic component (SEC) was determined using quick-release tests to obtain 1) the MT stiffness index from the slope of either linear stiffness-torque (SI(MT-Torque)) or stiffness-EMG (SI(MT-EMG)) relationships and 2) passive stiffness from the intercept point with the ordinate. Finally, the SEC active (α(0)) and passive fractions (C(passive)) were separated as described by Morgan (Am J Physiol, 1977), using alpha-torque (α(0-Torque,) C(passive-Torque)) or alpha-EMG (α(0-EMG,) C(passive-EMG)) relationships. No significant differences in SI(MT-Torque) or α(0-Torque) were observed between OW and CON. SI(MT-EMG) or α(0-EMG) values were significantly different between OW and CON, which indicate an increase in MT stiffness. In all cases, passive stiffness (K(p), C(passive-torque), C(passive-EMG)) was significantly greater in OW but independent of the activation capacities. These results indicate that a weight-related additional loading of the MT structures in OW children caused the MT system to response accordingly to the functional demand, i.e., higher stiffness of the MT structures due to a concomitant increase in the stiffness of the SEC passive and active fraction. This study also reveals that possible differences in the activation capacities influence the determination of MT stiffness of the SEC active fraction.

Head Position Comparison between Students with Normal Hearing and Students with Sensorineural Hearing Loss

Introduction Head sense position is coordinated by sensory activity of the vestibular system, located in the inner ear. Children with sensorineural hearing loss may show changes in the vestibular system as a result of injury to the inner ear, which can alter the sense of head position in this population. Aim Analyze the head alignment in students with normal hearing and students with sensorineural hearing loss and compare the data between groups. Methods This prospective cross-sectional study examined the head alignment of 96 students, 48 with normal hearing and 48 with sensorineural hearing loss, aged between 7 and 18 years. The analysis of head alignment occurred through postural assessment performed according to the criteria proposed by Kendall et al. For data analysis we used the chi-square test or Fisher exact test. Results The students with hearing loss had a higher occurrence of changes in the alignment of the head than normally hearing students (p < 0.001). Forward head posture was the type of postural change observed most, occurring in greater proportion in children with hearing loss (p < 0.001), followed by the side slope head posture (p < 0.001). Conclusion Children with sensorineural hearing loss showed more changes in the head posture compared with children with normal hearing.

Dynamic balance performance of students with normal-hearing and with sensorineural hearing loss

Introducao: O equilibrio corporal humano e regulado pela atuacao sensorial do sistema vestibular, situado na orelha interna. Criancas com perda auditiva sensorioneural podem apresentar alteracoes no sistema vestibular e, consequentemente, no equilibrio corporal, em decorrencia da lesao na orelha interna.Objetivos: Avaliar o equilibrio dinâmico em escolares ouvintes e com perda auditiva sensorioneural e comparar os dados entre os grupos considerando os sexos e as faixas etarias.Metodos: Estudo de corte transversal, que avaliou 96 escolares, sendo 48 ouvintes e 48 com perda auditiva sensorioneural, de ambos os sexos, na faixa etaria entre sete e 18 anos. A avaliacao do equilibrio dinâmico foi realizada por meio do teste de Babinski-Weil e do teste de Fukuda. Para a analise dos dados foi utilizado o teste do qui-quadrado de Pearson, tendo em vista a distribuicao de normalidade dos dados.Resultados: Os escolares com perda auditiva apresentaram maior ocorrencia de alteracoes no equilibrio dinâmico comparado aos ouvintes: teste de Babinski-Weil e teste de Fukuda: (p<0,001). A mesma diferenca foi observada quando os voluntarios foram agrupados pelos sexos: feminino e masculino: teste de Babinski-Weil e teste de Fukuda: (p<0,001). Estratificando-se pelas faixas etarias, os resultados apontaram diferencas, entre todos os grupos etarios avaliados: teste de Babinski-Weil: sete a 14 anos: (p<0,001) e 15-18 anos: (p= 0,004), teste de Fukuda: sete a 18 anos: (p<0,001).Conclusao: Os escolares com perda auditiva apresentaram maior ocorrencia de alteracoes no equilibrio dinâmico que os ouvintes do mesmo sexo e faixa etaria.Introduction: The human body balance is regulated by sensory activity of the vestibular system, located in the inner ear. Children with sensorineural hearing loss may show changes in the vestibular system and, consequently, body balance disorders, probably due to damage in the inner ear. Objectives: To evaluate the dynamic balance in students who hear and those who have sensorineural hearing loss and to compare data between groups considering the sex and age groups. Methods: Cross-sectional study, which evaluated 96 school children. 48 listeners and 48 with sensorineural hearing loss, of both sexes aged between seven to 18 years. The dynamic balance evaluation was performed using the Babinski-Weil test and Fukuda test. For data analysis the Pearson chi-square test with a view to distribution data normality was used. Results: The students with hearing loss had more changes in dynamic balance compared to listeners: Babinski-Weil test and Fukuda test: (p<0.001). The same difference was found when subjects were grouped by the gender: male and female: Babinski-Weil test and Fukuda test: (p<0.001). Stratifying by the age groups, the results showed differences among all age groups evaluated: Babinski-Weil test: seven to 14 years: (p<0.001) and 15-18 years: (p= 0.004). Fukuda test: seven to 18 years: (p<0.001). Conclusion: Students with hearing loss had higher dynamic balance changes than listeners of the same sex and age.

Desempenho do equilíbrio dinâmico de escolares ouvintes e com perda auditiva sensorioneural

Introducao: O equilibrio corporal humano e regulado pela atuacao sensorial do sistema vestibular, situado na orelha interna. Criancas com perda auditiva sensorioneural podem apresentar alteracoes no sistema vestibular e, consequentemente, no equilibrio corporal, em decorrencia da lesao na orelha interna.Objetivos: Avaliar o equilibrio dinâmico em escolares ouvintes e com perda auditiva sensorioneural e comparar os dados entre os grupos considerando os sexos e as faixas etarias.Metodos: Estudo de corte transversal, que avaliou 96 escolares, sendo 48 ouvintes e 48 com perda auditiva sensorioneural, de ambos os sexos, na faixa etaria entre sete e 18 anos. A avaliacao do equilibrio dinâmico foi realizada por meio do teste de Babinski-Weil e do teste de Fukuda. Para a analise dos dados foi utilizado o teste do qui-quadrado de Pearson, tendo em vista a distribuicao de normalidade dos dados.Resultados: Os escolares com perda auditiva apresentaram maior ocorrencia de alteracoes no equilibrio dinâmico comparado aos ouvintes: teste de Babinski-Weil e teste de Fukuda: (p<0,001). A mesma diferenca foi observada quando os voluntarios foram agrupados pelos sexos: feminino e masculino: teste de Babinski-Weil e teste de Fukuda: (p<0,001). Estratificando-se pelas faixas etarias, os resultados apontaram diferencas, entre todos os grupos etarios avaliados: teste de Babinski-Weil: sete a 14 anos: (p<0,001) e 15-18 anos: (p= 0,004), teste de Fukuda: sete a 18 anos: (p<0,001).Conclusao: Os escolares com perda auditiva apresentaram maior ocorrencia de alteracoes no equilibrio dinâmico que os ouvintes do mesmo sexo e faixa etaria.Introduction: The human body balance is regulated by sensory activity of the vestibular system, located in the inner ear. Children with sensorineural hearing loss may show changes in the vestibular system and, consequently, body balance disorders, probably due to damage in the inner ear. Objectives: To evaluate the dynamic balance in students who hear and those who have sensorineural hearing loss and to compare data between groups considering the sex and age groups. Methods: Cross-sectional study, which evaluated 96 school children. 48 listeners and 48 with sensorineural hearing loss, of both sexes aged between seven to 18 years. The dynamic balance evaluation was performed using the Babinski-Weil test and Fukuda test. For data analysis the Pearson chi-square test with a view to distribution data normality was used. Results: The students with hearing loss had more changes in dynamic balance compared to listeners: Babinski-Weil test and Fukuda test: (p<0.001). The same difference was found when subjects were grouped by the gender: male and female: Babinski-Weil test and Fukuda test: (p<0.001). Stratifying by the age groups, the results showed differences among all age groups evaluated: Babinski-Weil test: seven to 14 years: (p<0.001) and 15-18 years: (p= 0.004). Fukuda test: seven to 18 years: (p<0.001). Conclusion: Students with hearing loss had higher dynamic balance changes than listeners of the same sex and age.

Influence of muscle activity on musculotendinous stiffness quantification in stunted, prepubertal children

The quick-release technique to estimate musculotendinous (MT) stiffness has been extensively used over the last years, in both animals and humans, to gain insights in the adaptive process of the series elastic component (SEC). Recently, MT stiffness quantification, i.e., SEC behavior, has been revisited for subjects not able to fully activate their muscles (effects of long-term spaceflight or non-mature muscles). Such a phenomenon can also be encountered in stunted children. So, the aim of the present study was to analyze the effect of stunting on MT stiffness taking into account possible defect in muscle activation. For this study, 20 eutrophic children (EU) with an average age of 9years±4months were compared to 11age matched stunted children (S) evaluated by the height-to-age index. The MT stiffness index was obtained with regard to stiffness-torque and stiffness-soleus EMG relationships. The children of the S group presented a significantly lower Maximal Voluntary Contraction (MVC) in plantar flexion in comparison with children of the EU group (-37.8%). The significantly lower MT stiffness index for S children (-42.6%) was evidenced only when quantified with regard to the stiffness-soleus EMG relationship (66.5±42.8 vs. 38.2±19.9 Nmrad(-1)%(-1)). Possible delay in fiber type differentiation or tendinous structure maturation can account for the lower MT stiffness index in S children. In conclusion, stunting during early childhood delays the differentiation and maturation processes of musculotendinous structures as shown by the lower MT stiffness quantified with regards to muscle activity, also altered for stunted prepubertal children.

Balance performance of children and adolescents with sensorineural hearing loss: Repercussions of hearing loss degrees and etiological factors

INTRODUCTION Some studies have demonstrated a parallelism between the extent of hearing loss and the frequency of vestibular dysfunction in children with sensorineural hearing loss (SNHL). Despite this, little is known about the repercussion of degrees of hearing loss and etiological factors on the balance performance in this children. OBJECTIVE Compare the balance performance between normal hearing (NH) children and those with SNHL, considering the sex and age range of the sample, and analyze balance performance according to the degrees of hearing loss and etiological factors in the latter group. METHODS Cross-sectional study that assessed 96 children (48 NH and 48 with SNHL), aged between 7 and 18 years old. The balance performance was assessed by the Brazilian version of the Pediatric Balance Scale, validated for Brazilian child population and the Mann-Whitney test used for statistical analysis. RESULTS The group with SNHL showed lower average balance performance compared to NH (p = 0.000). This was also observed when the children were grouped by sex: female and male (p = 0.001). The same difference occurred when the children were stratified by age group: 7-14 years old (p = 0.000). There were no differences between the balance performance of the groups according to the degrees of hearing loss (p = 0.236) and the children with prematurity or post-natal meningitis as an etiological factor demonstrated the worst balance performance. CONCLUSION The children with SNHL showed worse balance performance compared to NH of the same sex and age range between seven to fourteen years. There were no differences between balance performance and hearing loss degrees, and those children with prematurity or post-natal meningitis as an etiological factor demonstrated the worst balance performances.

Desempeño del equilibrio dinámico de escolares oyentes y con pérdida auditiva sensorineural

Introducao: O equilibrio corporal humano e regulado pela atuacao sensorial do sistema vestibular, situado na orelha interna. Criancas com perda auditiva sensorioneural podem apresentar alteracoes no sistema vestibular e, consequentemente, no equilibrio corporal, em decorrencia da lesao na orelha interna.Objetivos: Avaliar o equilibrio dinâmico em escolares ouvintes e com perda auditiva sensorioneural e comparar os dados entre os grupos considerando os sexos e as faixas etarias.Metodos: Estudo de corte transversal, que avaliou 96 escolares, sendo 48 ouvintes e 48 com perda auditiva sensorioneural, de ambos os sexos, na faixa etaria entre sete e 18 anos. A avaliacao do equilibrio dinâmico foi realizada por meio do teste de Babinski-Weil e do teste de Fukuda. Para a analise dos dados foi utilizado o teste do qui-quadrado de Pearson, tendo em vista a distribuicao de normalidade dos dados.Resultados: Os escolares com perda auditiva apresentaram maior ocorrencia de alteracoes no equilibrio dinâmico comparado aos ouvintes: teste de Babinski-Weil e teste de Fukuda: (p<0,001). A mesma diferenca foi observada quando os voluntarios foram agrupados pelos sexos: feminino e masculino: teste de Babinski-Weil e teste de Fukuda: (p<0,001). Estratificando-se pelas faixas etarias, os resultados apontaram diferencas, entre todos os grupos etarios avaliados: teste de Babinski-Weil: sete a 14 anos: (p<0,001) e 15-18 anos: (p= 0,004), teste de Fukuda: sete a 18 anos: (p<0,001).Conclusao: Os escolares com perda auditiva apresentaram maior ocorrencia de alteracoes no equilibrio dinâmico que os ouvintes do mesmo sexo e faixa etaria.Introduction: The human body balance is regulated by sensory activity of the vestibular system, located in the inner ear. Children with sensorineural hearing loss may show changes in the vestibular system and, consequently, body balance disorders, probably due to damage in the inner ear. Objectives: To evaluate the dynamic balance in students who hear and those who have sensorineural hearing loss and to compare data between groups considering the sex and age groups. Methods: Cross-sectional study, which evaluated 96 school children. 48 listeners and 48 with sensorineural hearing loss, of both sexes aged between seven to 18 years. The dynamic balance evaluation was performed using the Babinski-Weil test and Fukuda test. For data analysis the Pearson chi-square test with a view to distribution data normality was used. Results: The students with hearing loss had more changes in dynamic balance compared to listeners: Babinski-Weil test and Fukuda test: (p<0.001). The same difference was found when subjects were grouped by the gender: male and female: Babinski-Weil test and Fukuda test: (p<0.001). Stratifying by the age groups, the results showed differences among all age groups evaluated: Babinski-Weil test: seven to 14 years: (p<0.001) and 15-18 years: (p= 0.004). Fukuda test: seven to 18 years: (p<0.001). Conclusion: Students with hearing loss had higher dynamic balance changes than listeners of the same sex and age.