Mechanical loading rescues mechanoresponsiveness in a human osteoarthritis explant model despite Wnt activation.

OBJECTIVES: Optimizing rehabilitation strategies for osteoarthritis necessitates a comprehensive understanding of chondrocytes' mechanoresponse in both health and disease, especially in the context of the interplay between loading and key pathways involved in osteoarthritis (OA) development, like canonical Wnt signaling. This study aims to elucidate the role of Wnt signaling in the mechanoresponsiveness of healthy and osteoarthritic human cartilage. METHODS: We used an ex-vivo model involving short-term physiological mechanical loading of human cartilage explants. First, the loading protocol for subsequent experiments was determined. Next, loading was applied to non-OA-explants with or without Wnt activation with CHIR99021. Molecular read-outs of anabolic, pericellular matrix and matrix remodeling markers were used to assess the effect of Wnt on cartilage mechanoresponse. Finally, the same set-up was used to study the effect of loading in cartilage from patients with established OA. RESULTS: Our results confirm that physiological loading maintains expression of anabolic genes in non-OA cartilage, and indicate a deleterious effect of Wnt activation in the chondrocyte mechanoresponsiveness. This suggests that loading-induced regulation of chondrocyte markers occurs downstream of canonical Wnt signaling. Interestingly, our study highlighted contrasting mechanoresponsiveness in the model of Wnt activation and the established OA samples, with established OA cartilage maintaining its mechanoresponsiveness, and mechanical loading rescuing the chondrogenic phenotype. CONCLUSION: This study provides insights into the mechanoresponsiveness of human cartilage in both non-OA and OA conditions. These findings hold the potential to contribute to the development of strategies that optimize the effect of dynamic compression by correcting OA pathological cell signaling.

Morphometry and morphology of fish otoliths on the coast of the state of Maranhão, Brazil.

The main objective of this study was to evaluate the biometric relationships between the species Bagre bagre, Lutjanus synagris and Nebris microps and their otoliths. The relationship between the size of the otolith (length and weight) and the size of the fish (standard length and total weight) was determined using the linear regression model (y = a + bx). For the morphological description, the otoliths of three specimens were selected by standard length class (10mm). The morphological characters analyzed were chosen according to traditional literature. Three hundred eight specimens of B. bagre, 200 of L. synagris and 237 of N. microps were analyzed. Throughout the collection period, the source of the capture of individuals was the municipality of Raposa. The linear correlations for fish and otolith length for B. bagre were 0.9129 and 0.9652, respectively. For L. synagris, the coefficients were 0.8634 and 0.8672, while for N. microps, 0.9597 and 0.8636, respectively. The morphological classification of L. synagris and N. microps is of the Saggita type, and the B. bagre species is of the Lapillus type. From the data presented here, it is possible to observe that otolith morphometric and morphological data can serve as a parameter to estimate the relationship between the fish and the otolith in terms of its biomass and the length of an individual and a population.

A ubiquitous factor (HF-1a) and a distinct muscle factor (HF-1b/MEF-2) form an E-box-independent pathway for cardiac muscle gene expression.

Recent studies have identified a conserved 28-bp element (HF-1) within the rat cardiac MLC-2 gene which confers cardiac muscle-specific and inducible expression during myocardial cell hypertrophy. Utilizing a combination of independent experimental approaches, this study characterizes two cardiac nuclear factors which bind to HF-1, a ubiquitous factor (HF-1a), and an A + T-rich binding factor (HF-1b) which is preferentially expressed in differentiated cardiac and skeletal muscle cells. The HF-1a binding site is located in a core region of the 28-bp conserved element, immediately upstream from the A + T-rich HF-1b site, which is homologous to the MEF-2 site found in a number of muscle genes. By a number of separate criteria (gel mobility shift, competition, and mutagenesis studies), HF-1b and MEF-2 appear to be indistinguishable and thus are either identical or closely related muscle factors. Transient assays of luciferase reporter genes containing point mutations throughout the 28-bp HF-1 regulatory element document the importance of both the HF-1a and HF-1b sites in transient assays in ventricular muscle cells. In the native 250-bp MLC-2 promoter fragment, mutations in the single E box had little effect on cardiac muscle specificity, while point mutations in either the HF-1a or HF-1b binding site significantly reduced promoter activity, underscoring the importance of both the HF-1a and HF-1b sites in the transcriptional activation of this cardiac muscle gene. Thus, this study provides evidence that a novel, ubiquitous factor (HF-1a) and a muscle factor (HF-1b/MEF-2) can form a novel, E-box-independent pathway for muscle-specific expression in ventricular cardiac muscle cells.

A conserved 28-base-pair element (HF-1) in the rat cardiac myosin light-chain-2 gene confers cardiac-specific and alpha-adrenergic-inducible expression in cultured neonatal rat myocardial cells.

To study the transcriptional regulatory mechanisms which mediate cardiac-specific and inducible expression during myocardial cell hypertrophy, we have extensively characterized the rat cardiac myosin light-chain-2 (MLC-2) gene as a model system. The MLC-2 gene encodes a relatively abundant contractile protein in slow skeletal and cardiac muscle and is upregulated during in vivo cardiac hypertrophy and alpha-adrenergic-mediated hypertrophy of neonatal rat myocardial cells. In transient expression assays employing a series of MLC-2-luciferase constructs, recent studies have identified a 250-bp fragment which is sufficient for both cardiac-specific and alpha-adrenergic-inducible expression. Within this 250-bp fragment lie three regions (HF-1, HF-2, and HF-3), each greater than 10 bp in length, which are conserved between the chicken and rat cardiac MLC-2 genes, suggesting their potential role in the regulated expression of this contractile protein gene. As assessed by substitution mutations within each of the conserved regions, the present study demonstrates that HF-1 and HF-2 are important in both cardiac-specific and inducible expression, while HF-3 has no detectable role in the regulated expression of the MLC-2 gene in transient expression assays. HF-1 sequences confer both cardiac-specific and inducible expression to a neutral promoter-luciferase construct but have no significant effect in the skeletal muscle or nonmuscle cell contexts. Thus, these studies have identified a new cardiac-specific regulatory element (HF-1) which plays a role in both cardiac-specific and inducible expression during myocardial cell hypertrophy.

A novel, tissue-restricted zinc finger protein (HF-1b) binds to the cardiac regulatory element (HF-1b/MEF-2) in the rat myosin light-chain 2 gene.

The AT-rich element MEF-2 plays an important role in the maintenance of the muscle-specific expression of a number of cardiac and skeletal muscle genes. In the MLC-2 gene, an AT-rich element (HF-1b) which contains a consensus MEF-2 site is required for cardiac tissue-specific expression. The present study reports the isolation and characterization of a cDNA which encodes a novel C2H2 zinc finger (HF-1b) that binds in a sequence-specific manner to the HF-1b/MEF-2 site in the MLC-2 promoter. A number of independent criteria suggest that this HF-1b zinc finger protein is a component of the endogenous HF-1b/MEF-2 binding activity in cardiac muscle cells and that it can serve as a transcriptional activator of the MLC-2 promoter in transient assays. These studies suggest that, in addition to the previously reported RSRF proteins, structurally divergent transcriptional factors can bind to MEF-2-like sites in muscle promoters. These results underscore the complexity of the regulation of the muscle gene program via these AT-rich elements in cardiac and skeletal muscle.

Role of crevice in the occurrence of hemoglobin in saliva.

The aim of the present study was to analyze the role of the gingival-periodontal component in the presence of blood in saliva. We studied a population of 184 adult patients composed of 101 totally edentulous patients with no oral mucosa lesions and 83 dentulous patients with clinically healthy gums. Saliva samples obtained by spontaneous salivation were collected in sterile containers. Qualitative and quantitative evaluation of each of the samples was performed. 67% of the dentulous patients tested positive for hemoglobin in saliva. None of the patients in the totally edentulous group exhibited hemoglobin in saliva. These data suggest that the periodontal condition is an essential factor for the presence of hemoglobin in saliva.

Considerações sobre os principais indicadores utilizados em estudos de nutrição com ruminantes / Considerations on the main markers used in nutrition studies with rumlnants / Consideraciones acerca de los principales indicadores utilizados en estudios de nutrición con rumiantes

ABSTRACT: In animal metabolism studies, sometimes it's not possible to obtain the desired information in a direct way, and therefore it is necessary to make use of substances designated as markers, which allow the estimative of determined physiological and nutritional parameters. The markers are grouped into internal, which are represented by indigestible materials occurring naturally on a diet, and external markers, which are materials that are either added to the diet or administered orally or intraruminally to the animal. However, in order to be used as a marker, a substance must comply with some essential criteria. There are several problems associated to the use of markers, specially their incomplete recovery in the duodenum or faeces. Each group of markers has its own characteristics, which will defi ne its application. Chromium oxide is the most extensively used external marker, presenting a great wide application, especially because it is easy to use and it cost is low.Among the internal markers, the use of the indigestible fi bre portion of the foods is recommended for its facility to use and has demonstrated reliable and accurate values in several studies. The use of n-alkanes, especially for the intake estimation in grazing animals, has provided quite satisfactory values. Several criteria, like the facility to use and determination must be established to guide the decision by the marker which better adapts to the parameters that will be assessed.KEYWORDS: Markers, animal metabolism, methodology, nutrition

RESUMO: Em estudos de metabolismo animal, muitas vezes, não é possível obter de forma direta a informação desejada, sendo necessário o uso de substâncias denominadas indicadores, possibilitando a estimativa de determinados parâmetros fi siológicos e nutricionais. Os indicadores são divididos em internos, representados por substâncias indigestíveis presentes naturalmente na dieta, ou externos, quando adicionados à dieta ou fornecidos via oral ou ruminal aos animais. Para que uma substância possa ser utilizada como indicador, deve atender a determinados critérios, sendo vários os problemas associados ao seu uso, especialmente a incompleta recuperação do indicador no duodeno ou fezes. Cada grupo de indicadores possui suas características próprias, defi nindo em que situação ele melhor se aplica. O óxido crômico é o indicador externo mais amplamente difundido, apresentando uma grande amplitude de aplicações, associada ainda às vantagens de fácil utilização e baixo custo. Entre os indicadores internos, a utilização da porção da fi bra indigestível dos alimentos vem se destacando pela facilidade de uso e bons resultados apresentados pela literatura. A utilização dos n-alcanos, sobretudo em estimativa de consumo de animais em regime de pastejo, tem apresentado resultados bastante satisfatórios. No momento da escolha, devem ser estabelecidos critérios, como facilidade de uso e determinação, que norteiem a decisão pelo indicador que melhor se adapte aos parâmetros a ser avaliados

RESUMEN: En estudios de metabolismo animal, muchas veces no es posible obtener de forma directa la información deseada, debiéndose entonces, hacer uso de sustancias denominadas indicadores, haciendo posible con eso la estimación de determinados parámetros fi siológicos y nutricionales. Los indicadores son divididos en internos y externos, existiendo una gran variedad de indicadores que deben ser escogidos de acuerdo con la respuesta a ser encontrada. Por tanto, para que una sustancia pueda ser utilizada como indicador, ella debe atender a determinados criterios básicos. Diversos son los problemas asociados al uso de indicadores, especialmente su incompleta recuperación en el duodeno o heces. Cada grupo de indicadores posee sus propias características, defi niéndose en que situación se aplica mejor. El óxido de cromo es el indicador externo mas ampliamente difundido, presentando una grande amplitud de aplicaciones, asociado además a las ventajas de fácil uso y bajo costo. Entre los indicadores internos, la utilización de la porción de la fi bra indigestible de los alimentos fue destacada por la facilidad de uso y de buenos resultados presentados por la literatura. La utilización de n-alcanos, sobre todo en estimaciones de consumo de alimento de animales en régimen de pastoreo presentó resultados bastante satisfactorios. En el momento de elegir el indicador para ser utilizado, deben ser establecidos criterios que norteen la decisión por el indicador que mejor se adecue a los parámetros evaluados y a sus facilidades de uso y determinación.

Role of crevice in the occurrence of hemoglobin in saliva

The aim of the present study was to analyze the role of the gingival-periodontal component in the presence of blood in saliva. We studied a population of 184 adult patients composed of 101 totally edentulous patients with no oral mucosa lesions and 83 dentulous patients with clinically healthy gums. Saliva samples obtained by spontaneous salivation were collected in sterile containers. Qualitative and quantitative evaluation of each of the samples was performed. 67

of the dentulous patients tested positive for hemoglobin in saliva. None of the patients in the totally edentulous group exhibited hemoglobin in saliva. These data suggest that the periodontal condition is an essential factor for the presence of hemoglobin in saliva.