Restoration of photosystem II photochemistry and carbon assimilation and related changes in chlorophyll and protein contents during the rehydration of desiccated Xerophyta scabrida leaves

Recovery of photosynthesis in rehydrating desiccated leaves of the poikilochlorophyllous desiccation-tolerant plant Xerophyta scabrida was investigated. Detached leaves were remoistened under 12 h light/dark cycles for 96 h. Water, chlorophyll (Chl), and protein contents, Chl fluorescence, photosynthesis–CO2 concentration response, and the amount and activity of Rubisco were measured at intervals during the rehydration period. Leaf relative water contents reached 87% in 12 h and full turgor in 96 h. Chl synthesis was slower before than after 24 h, and Chla:Chlb ratios changed from 0.13 to 2.6 in 48 h. The maximum quantum efficiency recovered faster during rehydration than the photosystem II operating efficiency and the efficiency factor, which is known to depend mainly on the use of the electron transport chain products. From 24 h to 96 h of rehydration, net carbon fixation was Rubisco limited, rather than electron transport limited. Total Rubisco activity increased during rehydration more than the Rubisco protein content. Desiccated leaves contained, in a close to functional state, more than half the amount of the Rubisco protein present in rehydrated leaves. The results suggest that in X. scabrida leaves Rubisco adopts a special, protective conformation and recovers its activity during rehydration through modifications in redox status

Relationship between knee and ankle degeneration in a population of organ donors

<p>Abstract</p> <p>Background</p> <p>Osteoarthritis (OA) is a progressive degenerative condition of synovial joints in response to both internal and external factors. The relationship of OA in one joint of an extremity to another joint within the same extremity, or between extremities, has been a topic of interest in reference to the etiology and/or progression of the disease.</p> <p>Methods</p> <p>The prevalence of articular cartilage lesions and osteophytes, characteristic of OA, was evaluated through visual inspection and grading in 1060 adult knee/tali pairs from 545 cadaveric joint donors.</p> <p>Results</p> <p>Joint degeneration increased more rapidly with age for the knee joint, and significantly more knee joints displayed more severe degeneration than ankle joints from as early as the third decade. Women displayed more severe knee degeneration than did men. Severe ankle degeneration did not exist in the absence of severe knee degeneration. The effect of weight on joint degeneration was joint-specific whereby weight had a significantly greater effect on the knee. Ankle grades increasingly did not match within a donor as the grade of degeneration in either the left or the right knee increased.</p> <p>Conclusions</p> <p>Gender and body type have a greater effect on knee joint integrity as compared to the ankle, suggesting that knees are more prone to internal causative effects of degeneration. We hypothesize that the greater variability in joint health between joints within an individual as disease progresses from normal to early signs of degeneration may be a result of mismatched limb kinetics, which in turn might lead to joint disease progression.</p

Efeitos na medida do ângulo Q com a contração isométrica voluntária máxima do músculo quadricipital Efectos en la medida del ángulo Q con la contracción isométrica voluntária máxima del musculo cuadricipital Effects in the Q angle measurement with maximal voluntary isometric contraction of the quadriceps muscle

A proposta deste estudo foi verificar a diferença entre o ângulo quadricipital em indivíduos sintomáticos e assintomáticos, em duas diferentes situações de exame, com o quadríceps relaxado e em contração isométrica voluntária máxima (CIVM) através da mensuração radiográfica para contribuir na avaliação e tratamento de pacientes com disfunção femoropatelar (DFP). Foram avaliadas 20 mulheres (40 joelhos), com idade média de 21 anos, através de método radiológico padronizado. Os indivíduos foram posicionados em decúbito dorsal com um estabilizador podálico em "U", com os membros inferiores relaxados, com a utilização de película de chumbo sobre a tuberosidade anterior da tíbia. Para a análise estatística foram utilizadas as médias dos grupos assintomático e sintomático, em estado de relaxamento e em CIVM, e o teste t de Student, com nível de significância de p < 0,05. Os valores médios do ângulo Q para os assintomáticos foram de 17,15° em relaxamento e de 14,5° em CIVM, enquanto os sintomáticos apresentaram 21,45° e 15,8°, respectivamente. Nos resultados para a análise da igualdade entre os grupos sintomáticos e assintomáticos no estado de relaxamento obteve-se p = 0,004, e para o estado de contração isométrica voluntária máxima, p = 0,29. Considerando os dados obtidos no presente estudo, pode-se verificar que em estado de relaxamento há diferença entre o valor do ângulo Q entre indivíduos sintomáticos e assintomáticos, sendo este maior nos portadores da DFP, enquanto que em estado de contração isométrica máxima do músculo quadricipital não houve diferença estatística, ocorrendo redução do ângulo em ambos os grupos.<br>La propuesta de este estudio era verificar la diferencia entre el ángulo cuadricipital en los individuos sintomáticos y asintomáticos, en dos situaciones diferentes del examen físico; con el cuadriceps relajado y en el máximo de la reducción isométrico voluntario (CIVM) a través de la medida radiográfica para contribuir en la evaluación y el tratamiento de pacientes con trastorno fémoro-patelar (DFP). Se estimaron 20 mujeres (40 rodillas), con la edad media de 21 años, a través de método radiológico estandardizado. Los individuos se pusieron en decúbito con un estabilizador podálico en "U", con los miembros inferiores relajados, con el uso de película de plomo en la tuberosidad anterior de la espinilla. Para el análisis estadístico se usaron las medias del grupo asintomático y sintomático, en estado de relajación y en CIVM, y la prueba del test t, con un nivel de significancia de p < 0,05. Los valores medios del ángulo Q para los asintomáticos fueron de 17,15° en la relajación y de 14,5° en CIVM, mientras los sintomáticos presentaron 21,45° y 15,8°, respectivamente. En los resultados para el análisis de la igualdad entre los grupos sintomático y asintomático en el estado de relajación se obtuvo p = 0,004, y para el estado de reducción isométrica voluntaria máximo, p = 0,29. Considerando los datos obtenidos en el estudio presente, puede verificarse que en el estado de relajación hay diferencia entre el valor del ángulo Q entre los individuos sintomáticos y asintomáticos, siendo este más grande en los portadores de DFP, mientras en el estado de contracción isométrica máxima del músculo cuadriceps no presentó diferencia estadística, habiendo reducción del ángulo en ambos los grupos.<br>The purpose of this study was to analyze the difference between the angle of the quadriceps in symptomatic and asymptomatic individuals in two different examination situations, having the quadriceps relaxed and in a maximal voluntary isometric contraction (MVIC) through radiographic measurement, aiming to contribute to the assessment and treatment of patients with patelofemoral disorder (PFD). Through the standard radiological method twenty 21 years old mean women (40 knees) were assessed. All individuals were positioned supine using a U-podalic stabilizer, having their lower limbs relaxed, using a plumb film on the anterior tuberosity of the tibia. For the statistical analysis, the averages for the asymptomatic and symptomatic groups in a relaxed and MVIC status, as well as the Student's t-test with p < 0.05 significance level were used. The mean values to the Q angle compared to the asymptomatic group were 17.15º on relaxation, and 14.5º on MVIC, while the asymptomatic group presented 21.45º, and 15.8º, respectively. The results in the equality analysis between the symptomatic and asymptomatic groups on the relaxed status attained a p = 0.004, and to the maximal voluntary isometric contraction, p = 0.29. Considering the data attained in the present study, it can be verified that in a relaxing status, there is a difference between the value of the Q angle among symptomatic and asymptomatic individuals, being found a higher value in the FPD bearers, while in a maximal isometric contraction of the quadriceps muscle no statistical difference was found in the present study, with a reduction in the angle in both groups