Postural control during single leg stance in individuals with clinical indication for combined reconstruction of the anterior cruciate and the anterolateral ligaments of the knee: a cross-sectional study.

BACKGROUND: Several studies have shown persistent postural control deficits and rotatory instability in patients after isolated Anterior Cruciate Ligament (ACL) reconstruction. There is evidence to support that the Anterolateral Ligament (ALL) plays an important role in the remaining anterolateral rotatory laxity of the knee. There are no further evidences in order to understand how patients with a combined ACL + ALL reconstruction surgery indication behave regarding postural control. The aim of this cross-sectional study was to assess if patients with a clinical indication for the combined ACL + ALL surgery showed a deficient postural control in single leg stance compared to subjects with a regular ACL reconstruction indication and to a control group. METHODS: An assessment of static postural control on single leg stance was performed on a force plate, with eyes open and closed, and the center of pressure (COP) displacement variables were analyzed: maximum and mean amplitude in anteroposterior (AP) and in mediolateral (ML) direction; mean velocity of displacement and area of displacement. Eighty-nine male individuals participated and were divided into 3 groups: ACL Group, ACL + ALL Group and Control Group. RESULTS: The ACL+ ALL Group showed significantly greater COP displacement in most variables in the injured leg for the eyes closed test, compared to the ACL Group, as detailed: Total ML displacement (9.8 ± 6.77 vs. 13.98 ± 6.64, p < 0.001); Mean ML displacement (2.58 ± 2.02 vs. 3.72 ± 1.99, p < 0.001); Total AP displacement (9.5 ± 3.97 vs. 11.7 ± 3.66, p = 0.001); Mean AP displacement (1.77 ± 0.87 vs. 2.27 ± 0.86, p = 0.001); Area of displacement (111.44 ± 127.3 vs. 183.69 ± 131.48, p < 0.001). CONCLUSION: Subjects with a clinical indication for ACL + ALL combined reconstruction surgery showed increased COP displacement compared to patients with indication for an ACL isolated reconstruction surgery.

Influence of Sex and Body Mass Index on the Thoracic Kyphosis and Lumbar Lordosis.

OBJECTIVES: The purpose of this study was to assess the influence of sex and body mass index (BMI) on the thoracic kyphosis and lumbar lordosis of adolescents and to assess the reliability and agreement of the flexicurve method for these measurements. METHODS: The study included 217 adolescents of both sexes, aged between 11 and 15 years, who were students from municipal schools in the city of São José dos Campos in São Paulo. The measurement of thoracic kyphosis and lumbar lordosis angles was performed using the flexicurve method. Descriptive analysis of the data, analysis of covariance for comparison between groups (by BMI and sex), assessment of reliability, and intrarater agreement were analyzed. RESULTS: There was a significant difference between the groups by BMI and sex only for lumbar lordosis. The obese group had greater lumbar angles for both sexes (female sex: 32.6° ± 7.8° [eutrophic]; 37.7° ± 7.3° [obese]; male sex: 25.3° ± 7.3° [eutrophic]; 32.2° ± 7.3° [obese]). In the comparison between the sexes, the greatest lumbar angles were found in the female sex (female sex: 32.6° ± 7.8°; male sex: 25.3° ± 7.3°) among the eutrophic. Excellent intrarater reliability was found for thoracic kyphosis (intraclass correlation coefficient, 0.86) and moderate for lumbar lordosis (intraclass correlation coefficient, 0.72). CONCLUSION: Sex and BMI were associated with lumbar lordosis in adolescents and were greater in individuals with obesity and female individuals. The flexicurve method was reliable and accurate for the assessment of thoracic kyphosis and lumbar lordosis in adolescents.

Quantitative Postural Analysis of Children With Congenital Visual Impairment.

OBJECTIVES: The aim of this study was to compare the postural alignment of children with visual impairment with that of children without visual impairment. METHODS: The sample studied was 74 children of both sexes ages 5 to 12 years. Of these, 34 had visual impairment and 40 were control children. Digital photos from the standing position were used to analyze posture. Postural variables, such as tilt of the head, shoulder position, scapula position, lateral deviation of the spine, ankle position in the frontal plane and head posture, angle of thoracic kyphosis, angle of lumbar lordosis, pelvis position, and knee position in the frontal and sagittal planes, were measured with the Postural Assessment Software 0.63, version 36 (SAPO, São Paulo, Brazil), with markers placed in predetermined bony landmarks. RESULTS: The main results of this study showed that children with visual impairment have increased head tilt (P < .001), shoulder deviation in frontal plane (P = .004), lateral deviation of the spine (P < .001), changes in scapula position (P = .012), higher thoracic kyphosis (P = .004), and lower lumbar lordosis (P < .001). CONCLUSIONS: Visual impairment influences postural alignment. Children with visual impairment had increased head tilt, uneven shoulders, greater lateral deviation of the spine, thoracic kyphosis, lower lumbar lordosis, and more severe valgus deformities on knees.

Modulation of Isometric Quadriceps Strength in Soccer Players With Transcranial Direct Current Stimulation: A Crossover Study.

Vargas, VZ, Baptista, AF, Pereira, GOC, Pochini, AC, Ejnisman, B, Santos, MB, João, SMA, and Hazime, FA. Modulation of isometric quadriceps strength in soccer players with transcranial direct current stimulation: a crossover study. J Strength Cond Res 32(5): 1336-1341, 2018-The aim of this study was to evaluate the effect of transcranial direct current stimulation (tDCS) on the maximum isometric muscle contraction (MVIC) of the knee extensors in soccer players at the preprofessional level. Twenty female soccer players aged 15-17 years (mean = 16.1; SD = 0.9) with 5.2 ± 2.6 years of training were randomly divided into 2 groups to receive either active or sham tDCS in a single session (2 mA; 0.057 mA·cm). The MVIC of the knee extensors was evaluated in both lower limbs by manual dynamometry in 5 sets of contractions divided into 4 blocks: (a) prestimulation, (b) during tDCS, (c) 30 minutes after tDCS, and (d) 60 minutes after tDCS. After an interval of 7 days, the groups were evaluated again, and the type of initial stimulation was inverted between participants. The MVIC of the knee extensors increased significantly during active tDCS (dominant limb (DL) = 0.4; IC = 0.1-0.8 N·Kg), 30 minutes after active tDCS (DL = 0.9; IC 0.4-1.4 N·Kg), and 60 minutes after active tDCS (DL = 1.0; IC 0.3-1.6 N·Kg) but not for sham tDCS. Our conclusion was that tDCS temporarily increases isometric quadriceps strength in adolescent female soccer players, which may be useful for both strength training and rehabilitation.

Relationships between static foot alignment and dynamic plantar loads in runners with acute and chronic stages of plantar fasciitis: a cross-sectional study

BACKGROUND: The risk factors for the development of plantar fasciitis (PF) have been associated with the medial longitudinal arch (MLA), rearfoot alignment and calcaneal overload. However, the relationships between the biomechanical variables have yet to be determined. OBJECTIVE: The goal of this study was to investigate the relationships between the MLA, rearfoot alignment, and dynamic plantar loads in runners with unilateral PF in acute and chronic phases. METHOD: Cross-sectional study which thirty-five runners with unilateral PF were evaluated: 20 in the acute phase (with pain) and 15 with previous chronic PF (without pain). The MLA index and rearfoot alignment were calculated using digital images. The contact area, maximum force, peak pressure, and force-time integral over three plantar areas were acquired with Pedar X insoles while running at 12 km/h, and the loading rates were calculated from the vertical forces. RESULTS: The multiple regression analyses indicated that both the force-time integral (R2=0.15 for acute phase PF; R2=0.17 for chronic PF) and maximum force (R2=0.35 for chronic PF) over the forefoot were predicted by an elevated MLA index. The rearfoot valgus alignment predicted the maximum force over the rearfoot in both PF groups: acute (R2=0.18) and chronic (R2=0.45). The rearfoot valgus alignment also predicted higher loading rates in the PF groups: acute (R2=0.19) and chronic (R2=0.40). CONCLUSION: The MLA index and the rearfoot alignment were good predictors of plantar loads over the forefoot and rearfoot areas in runners with PF. However, rearfoot valgus was demonstrated to be an important clinical measure, since it was able to predict the maximum force and both loading rates over the rearfoot.

Relationships between static foot alignment and dynamic plantar loads in runners with acute and chronic stages of plantar fasciitis: a cross-sectional study.

BACKGROUND: The risk factors for the development of plantar fasciitis (PF) have been associated with the medial longitudinal arch (MLA), rearfoot alignment and calcaneal overload. However, the relationships between the biomechanical variables have yet to be determined. OBJECTIVE: The goal of this study was to investigate the relationships between the MLA, rearfoot alignment, and dynamic plantar loads in runners with unilateral PF in acute and chronic phases. METHOD: Cross-sectional study which thirty-five runners with unilateral PF were evaluated: 20 in the acute phase (with pain) and 15 with previous chronic PF (without pain). The MLA index and rearfoot alignment were calculated using digital images. The contact area, maximum force, peak pressure, and force-time integral over three plantar areas were acquired with Pedar X insoles while running at 12 km/h, and the loading rates were calculated from the vertical forces. RESULTS: The multiple regression analyses indicated that both the force-time integral (R²=0.15 for acute phase PF; R²=0.17 for chronic PF) and maximum force (R²=0.35 for chronic PF) over the forefoot were predicted by an elevated MLA index. The rearfoot valgus alignment predicted the maximum force over the rearfoot in both PF groups: acute (R²=0.18) and chronic (R²=0.45). The rearfoot valgus alignment also predicted higher loading rates in the PF groups: acute (R²=0.19) and chronic (R²=0.40). CONCLUSION: The MLA index and the rearfoot alignment were good predictors of plantar loads over the forefoot and rearfoot areas in runners with PF. However, rearfoot valgus was demonstrated to be an important clinical measure, since it was able to predict the maximum force and both loading rates over the rearfoot.

Treatment time of ultrasound therapy interferes with the organization of collagen fibers in rat tendons.

BACKGROUND: The application time of therapeutic ultrasound is an infrequently studied dosimetric variable that affects tissue repair. OBJECTIVES: The aim of this study was to evaluate the effects of different treatment times of therapeutic ultrasound (US) on the organization of collagen fibers in the tendons of rats. METHOD: Forty Wistar rats were selected (300±45 g), and the rats were divided into five groups (n=8 for each group): Control, without tenotomy or any treatment; tenotomy group, with tenotomy and without treatment; US groups (US1, US2, and US3), subjected to tenotomy and treated with US for one, two, or three minutes per area of the transducer, respectively. The animals were sacrificed on the 12th post-operative day, and the tendons were surgically removed for analyses of the collagen fiber organization by means of birefringence analysis. RESULTS: The collagen fibers exhibited better aggregation and organization in the US3 group compared with the tenotomy group (p<0.05). CONCLUSIONS: The findings suggest that US applied for three minutes per treated area improves the organization of collagen fibers during rat tendon repair.

Treatment time of ultrasound therapy interferes with the organization of collagen fibers in rat tendons

BACKGROUND: The application time of therapeutic ultrasound is an infrequently studied dosimetric variable that affects tissue repair. OBJECTIVES: The aim of this study was to evaluate the effects of different treatment times of therapeutic ultrasound (US) on the organization of collagen fibers in the tendons of rats. METHOD: Forty Wistar rats were selected (300±45 g), and the rats were divided into five groups (n=8 for each group): Control, without tenotomy or any treatment; tenotomy group, with tenotomy and without treatment; US groups (US1, US2, and US3), subjected to tenotomy and treated with US for one, two, or three minutes per area of the transducer, respectively. The animals were sacrificed on the 12th post-operative day, and the tendons were surgically removed for analyses of the collagen fiber organization by means of birefringence analysis. RESULTS: The collagen fibers exhibited better aggregation and organization in the US3 group compared with the tenotomy group (p<0.05). CONCLUSIONS: The findings suggest that US applied for three minutes per treated area improves the organization of collagen fibers during rat tendon repair. .

Thoracic cirtometry in children with Duchenne muscular dystrophy--expansion of the method.

BACKGROUND: Thoracic cirtometry is a simple and accessible technique to evaluate chest mobility during forced breathing. However, it does not allow for the assessment of compensatory movements commonly used by people with chronic diseases, such Duchenne muscular dystrophy (DMD). DMD is a condition characterized by progressive and irreversible degeneration of the musculoskeletal system. OBJECTIVES: To expand the method of thoracic cirtometry to allow for the assessment of compensatory movements; to analyze the reliability of the tool; and to describe thoracic mobility of children with DMD during deep breathing. METHOD: Sixty boys, 30 with DMD (10.1±0.5 years) and 30 healthy controls (9.5±0.6 years) participated in the study. The expanded thoracic cirtometry was organized in two phases: 1. the body could move freely, allowing the assessment of compensatory movements (free thoracic cirtometry) and 2. the body without compensatory movements, allowing for the direct study of the movements of the chest (guided thoracic cirtometry). This method includes videotaping and systematic observation of body movements using descriptive and numeric data. We investigated reliability of these measures in both groups. RESULTS: Measures of axial and the xiphoid thoracic cirtometry (both free and guided) showed excellent reliability. All measures were significantly different between groups. In DMD boys, free thoracic cirtometry presented a greater value of chest expansion when compared with the guided measures, which probably occurred due to compensatory movements. The most commons were movements of the head, shoulder and torso. CONCLUSIONS: The expanded thoracic cirtometry method showed excellent reliability and achieved the objectives of determining measures of chest mobility and compensatory movements during deep breath. We suggested its use in the respiratory evaluation of children with DMD.

Thoracic cirtometry in children with Duchenne muscular dystrophy: expansion of the method / Toracometria em crianças com Distrofia Muscular de Duchenne: expansão do método

BACKGROUND: Thoracic cirtometry is a simple and accessible technique to evaluate chest mobility during forced breathing. However, it does not allow for the assessment of compensatory movements commonly used by people with chronic diseases, such Duchenne muscular dystrophy (DMD). DMD is a condition characterized by progressive and irreversible degeneration of the musculoskeletal system. OBJECTIVES: To expand the method of thoracic cirtometry to allow for the assessment of compensatory movements; to analyze the reliability of the tool; and to describe thoracic mobility of children with DMD during deep breathing. METHOD: Sixty boys, 30 with DMD (10.1±0.5 years) and 30 healthy controls (9.5±0.6 years) participated in the study. The expanded thoracic cirtometry was organized in two phases: 1. the body could move freely, allowing the assessment of compensatory movements (free thoracic cirtometry) and 2. the body without compensatory movements, allowing for the direct study of the movements of the chest (guided thoracic cirtometry). This method includes videotaping and systematic observation of body movements using descriptive and numeric data. We investigated reliability of these measures in both groups. RESULTS: Measures of axial and the xiphoid thoracic cirtometry (both free and guided) showed excellent reliability. All measures were significantly different between groups. In DMD boys, free thoracic cirtometry presented a greater value of chest expansion when compared with the guided measures, which probably occurred due to compensatory movements. The most commons were movements of the head, shoulder and torso. CONCLUSIONS: The expanded thoracic cirtometry method showed excellent reliability and achieved the objectives of determining measures of chest mobility and compensatory movements during deep breath. We suggested its use in the respiratory evaluation of children with DMD.

CONTEXTUALIZAÇÃO: A toracometria é um método simples e acessível para avaliar a mobilidade do tórax durante uma respiração forçada, mas não permite pesquisar os movimentos compensatórios utilizados por portadores de doenças crônicas, como Distrofia Muscular de Duchenne (DMD), caracterizada pela degeneração progressiva e irreversível da musculatura esquelética. OBJETIVOS: Ampliar método de avaliação pela toracometria, permitindo avaliação dos movimentos compensatórios; analisar a confiabilidade da ferramenta e descrever a mobilidade torácica de crianças com DMD durante respiração profunda. MÉTODO: Participaram 60 meninos, 30 com DMD (10,1±0,5 anos) e 30 saudáveis (9,5±0,6 anos). Organizou-se método de toracometria expandida em duas fases: livre movimentação corporal, permitindo avaliação de movimentos compensatórios (toracometria livre) e movimentação corporal sem movimentos compensatórios, permitindo o estudo dirigido aos movimentos do gradil costal (toracometria dirigida). Esse método prevê filmagem e observação sistemática dos movimentos, gerando dados numéricos e descritivos. O estudo de confiabilidade foi realizado para os dois grupos. RESULTADOS: As medidas de toracometria axial e xifoide (livres e dirigidas) apresentaram excelente confiabilidade. As medidas apresentaram diferenças significantes entre os grupos. Nas crianças com DMD, a toracometria livre apresentou valor de expansibilidade torácica maior quando comparada com a toracometria dirigida, provavelmente decorrente do auxílio dos movimentos compensatórios, sendo observados com maior frequência os associados à cabeça, ombro e tronco. CONCLUSÕES: O método de toracometria expandida apresentou excelente confiabilidade e permitiu descrever os movimentos compensatórios e da caixa torácica durante respiração profunda. Sugere-se sua utilização na avaliação respiratória de crianças com DMD.

The effects of plantar fasciitis and pain on plantar pressure distribution of recreational runners.

BACKGROUND: Plantar fasciitis is the third most frequent injury in runners. Despite its high prevalence, its pathogenesis remains inconclusive. The literature reports overload as the basic mechanism for its development. However, the way that these plantar loads are distributed on the foot surface of runners with plantar fasciitis and the effects of pain on this mechanical factor has not yet been investigated. Therefore, the aim of this study was to evaluate and compare the plantar pressure distributions during running in runners with symptom or history of plantar fasciitis and runners without the disease. METHODS: Forty-five recreational runners with plantar fasciitis (30 symptomatic and 15 with previous history of the disease) and 60 runners without plantar fasciitis (control group) were evaluated. Pain was assessed by a visual analogue scale. All runners were evaluated by means of the Pedar system insoles during running forty meters at a speed of 12(5%) km/h, using standard sport footwear. Two-way ANOVAS were employed to investigate the main and interaction effects between groups and plantar areas. FINDINGS: No interaction effects were found for any of the investigated variables: peak pressure (P = 0.61), contact area (P = 0.38), contact time (P = 0.91), and the pressure-time integral (P = 0.50). INTERPRETATION: These findings indicated that the patterns of plantar pressure distribution were not affected in recreational runners with plantar fasciitis when compared to control runners. Pain also did not interfere with the dynamic patterns of the plantar pressure distributions.

Postura do pé e classificação do arco plantar de adolescentes usuárias e não usuárias de calçados de salto alto / Foot posture and classification of the plantar arch among adolescent wearers and non-wearers of high-heeled shoes

Objetivos: Correlacionar a postura dos pés com o arco plantar de adolescentes usuárias e não usuárias de calçados de salto alto. MÉTODOS: Foram selecionadas 36 adolescentes, 16 no grupo de não usuárias e 20 no grupo de usuárias, com idade entre 13 e 20 anos. A postura do pé foi analisada por fotos nas condições descalça e com calçado de salto alto tipo Anabella, previamente padronizado, após terem permanecido com ele por uma hora. Sua análise foi realizada pelo software SAPO. A impressão plantar foi realizada descalça e, a partir dela, calculado o Índice de Chipaux - Smirak para classificação do arco plantar. Para análise estatística, utilizou-se o teste t pareado para verificar igualdade entre lados direito e esquerdo. Foi realizado o teste de aderência Shapiro Wilk e, então, a análise inferencial por meio dos testes não paramétricos de Wilcoxon, o teste de Mann-Whitney e a correlação de Spearman. O nível de significância adotado foi de 0,05. RESULTADOS: Não foi encontrada correlação entre o tipo de arco plantar e a postura do pé das adolescentes estudadas. Porém, o ângulo do retropé se mostrou significativamente diferente, apresentando varo de retropé após a colocação do calçado em ambos os grupos, e o arco plantar do grupo de usuárias apresentou valores menores quanto ao Índice Chipaux - Smirak. CONCLUSÕES: Não existe correlação entre a postura do pé e o tipo de arco plantar, embora essas variáveis tenham sofrido influência do calçado de salto alto. Artigo registrado na Australian New Zealand Clinical Trials Registry (ANZCTR) sob o número ACTRN12608000300370.

Objectives: To investigate the relationship between foot posture and plantar arch among adolescent wearers and non-wearers of high-heeled shoes. METHODS: Thirty-six female adolescents aged 13 to 20 years were selected and grouped as 16 high-heel non-wearers and 20 high-heel wearers. Foot posture was analyzed using photos, firstly barefoot and, secondly, after wearing previously standardized high-heeled platform shoes for an hour. The analysis was performed using the software SAPo. Barefoot impressions were taken, and the Chipaux-Smirak Index was calculated to classify the plantar arch of the foot. For statistical analyses, the paired t test was used to investigate equality between the right and left sides. The Shapiro-Wilk adherence test was performed, followed by inferential analysis using the non-parametric Wilcoxon test, the Mann-Whitney test and Spearman's correlation coefficient. The significance level used was 0.05. RESULTS: There was no correlation between the type of plantar arch and foot posture among the female adolescents studied. However, the rearfoot angle was significantly different, with rearfoot varus after wearing the shoes in both groups. The plantar arch in the wearers group presented smaller values for the Chipaux-Smirak Index. CONCLUSIONS: There is no correlation between foot posture and the type of plantar arch, although these variables are influenced by high-heeled shoes. Article registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) under the number ACTRN12608000300370.

Effects of phonophoresis with Arnica montana onto acute inflammatory process in rat skeletal muscles: an experimental study.

This study aimed at verifying the effects of phonophoresis associated with Arnica montana on the acute phase of an inflammatory muscle lesion. Forty Wistar male rats (300+/-50 g), of which the Tibialis Anterior muscle was surgically lesioned, were divided into four groups (n=10 each): control group received no treatment; the ultrasound group (US) was treated in pulsed mode with 1-MHz frequency, 0.5 W/cm(2) intensity (spatial and temporal average - SATA), duty cycle of 1:2 (2 ms on, 4 ms off, 50%), time of application 3 min per session, one session per day, for 3 days; the phonophoresis or ultrasound plus arnica (US+A) group was treated with arnica with the same US parameters plus arnica gel; and the arnica group (A) was submitted to massage with arnica gel, also for 3 min, once a day, for 3 days. Treatment started 24h after the surgical lesion. On the 4th day after lesion creation, animals were sacrificed and sections of the lesioned, inflamed muscle were removed for quantitative (mononuclear and polymorphonuclear cell count) and qualitative histological analysis. Collected data from the 4 groups were statistically analyzed and the significance level set at p<0.05. Results show higher mononuclear cell density in all three treated groups with no significant difference between them, but values were significantly different (p<0.0001) when compared to control group's. As to polymorphonuclear cell density, significant differences were found between control group (p=0.0134) and US, US+A and A groups; the arnica group presented lesser density of polymorphonuclear cells when compared (p=0.0134) to the other groups. No significant difference was found between US and US+A groups. While the massage with arnica gel proved to be an effective anti-inflammatory on acute muscle lesion in topic use, these results point to ineffectiveness of Arnica montana phonophoresis, US having seemingly checked or minimized its anti-inflammatory effect.

Caracterização do arco longitudinal plantar de crianças obesas por meio de índices da impressão plantar / Characterization of the longitudinal plantar arch of obese children using plantar print indexes

Objetivo: descrever o desenvolvimento do arco longitudinal medial (ALM) do pé de crianças obesas e verificar a concordância entre 5 índices da impressão plantar que caracterizam este arco. Métodos: 156 crianças obesas, ambos os sexos, idade entre 4 e 10 anos, pertencentes a escolas pública e privada da cidade de São Paulo, Brasil. As crianças classificadas como obesas foram selecionadas entre 1535 crianças estudantes de cinco escolas, com idade entre 4 e 10 anos. Em seguida foram coletadas as impressões plantares de cada criança e calculados índices que caracterizaram o ALM: índice de Cavanagh e Rodgers - CR, índice de Staheli - IS1 e IS2, índice de Chipaus-Smirak ICS e ângulo alfa de Clarke - AA. Resultados: CR, IS e ICS mostraram que a grande alteração na forma do ALM ocorre na transição dos 8 para os 9 anos e o AA mostra dois momentos, passagem dos 6 para os 7 anos e dos 8 para os 9 anos. De uma maneira geral, a classificação IS1 foi a mais discrepante para classificar o ALM nessas crianças e o CR a mais constante. Conclusões: observou-se que o ALM se forma mais tardiamente em crianças obesas (8 para 9 anos) em relação às crianças não obsesas (5 para 6 anos). Quanto aos índices houve semelhança na descrição do desenvolvimento do ALM entre CR, ICS e AA, sendo que o IS merece maior cuidado e restrição em seu uso.

Tight junctions in differentiating ameloblasts and odontoblasts differentially express ZO-1, occludin, and claudin-1 in early odontogenesis of rat molars.

Little is known about the expression of associated proteins during the assembly of tight junctions (TJs). We studied the distribution of ZO-1, occludin, and claudin-1 between differentiating ameloblasts and odontoblasts in molar tooth germs from 1- to 3-day-old rats by confocal laser scanning microscopy. Immunoreactivity for ZO-1 was strong at proximal and distal junctional complexes of differentiating ameloblasts, while it was weak and punctuate at the distal region of differentiating odontoblasts. Occludin was immunoreactive at distal and proximal complexes of early differentiating ameloblasts and at distal regions of differentiating odontoblasts. However, in more advanced stages, occludin was only evident at the proximal complex of ameloblasts. Claudin-1 was strongly detected at the proximal complex but it was weak at distal complex of late differentiating ameloblasts. Thus, our results showed that ZO-1, occludin, and claudin-1 are differentially expressed as TJs assemble for regulating polarity and/or paracellular permeability in differentiating ameloblasts and odontoblasts.

Expression of connexin 43 and ZO-1 in differentiating ameloblasts and odontoblasts from rat molar tooth germs.

We studied the distribution of connexin (Cx) 43 and ZO-1 by confocal laser scanning microscopy at early stages of dentinogenesis and amelogenesis. Labeling for Cx43 was observed at early stages of differentiation in both the epithelial cells and differentiating odontoblasts. Immunolabeling was detected at the distal and medial regions of undifferentiated ameloblasts and between cells from stratum intermedium and stellate reticulum. Differentiating odontoblasts exhibited immunoreaction for this antibody at their distal end. Immunoreactivity for ZO-1 was observed at regions that correspond to the proximal and distal junctional complexes of differentiating ameloblasts. Staining for ZO-1 was observed at apical regions of odontoblasts with a punctate appearance. In more advanced stages, expression of Cx43 was more evident on ameloblasts, especially at the junctional complexes. Punctate immunolabeling for Cx43 was observed at the lateral sides of differentiating ameloblasts and between the other cells of the enamel organ. Immunoreaction for ZO-1 in ameloblasts was more evident than at the previous stage. It was also observed at the distal end of differentiated odontoblasts. The present study showed that differentiating ameloblasts and odontoblasts express Cx43 and ZO-1 as early as the start of the differentiation process. In addition, the expression of these junctional proteins increases as differentiation of cells continues.