Glucose, pyruvate and lactate efflux by the perfused liver of a teleost, Clarias batrachus during aniso-osmotic exposure

Glucose, lactate and pyruvate efflux by the perfused liver of the walking catfish, Clarias batrachus was studied during aniso-osmotic exposure. During hypo-osmotic exposure (−80 mOsmol l⁻¹, maintained with NaCl), glucose, lactate and pyruvate efflux by the perfused liver significantly decreased by 55, 19 and 16%, respectively. During hyper-osmotic exposure (+80 mOsmol l⁻¹, maintained with NaCl), efflux increased by 57, 12 and 18%, respectively. Similar effects of glucose, lactate and pyruvate efflux by the perfused liver was also seen when the anisotonicity of the medium was adjusted with mannitol instead of NaCl. The decrease of glucose, lactate and pyruvate efflux during hypo-osmotic exposure was correlated with the stimulation of glycogen synthesis and the reverse was true during hyper-osmotic exposure. These observations were supported by changes in glycogen phosphorylase a (GPase a) and glycogen synthase a (GSase a) activities. During hypo-osmotic exposure (−80 mOsmol l⁻¹), the GPase a activity decreased by 1.93 fold and GSase a activity increased by 1.63 fold, while during hyper-osmotic exposure (+80 mOsmol l⁻¹), the GPase a activity increased by 1.58 fold and GSase a activity decreased by 1.95 fold. The total activity of both the enzymes were not effected by a short term exposure to aniso-osmotic conditions, suggesting that the alterations in GPase a and GSase a activity were mainly due to changes of their phosphorylation status during aniso-osmotic exposure. A direct correlation exists between glucose efflux and the hydration status of the perfused liver. These alterations of glucose metabolism are probably necessary by this walking catfish to meet the different energy demand, and also for maintenance of glucose homeostasis under osmotic stress.     

A comparison of time-lapse cinemicrography and flow cytometry for the study of accelerated cell-cycle transit

Abstract. Two methods for the study of cell-cycle progression, time-lapse cinemicrography (TLCM) and flow cytometry (FCM), were compared for their ability to measure the shortening of cell-cycle transit time induced by temporary inhibition of DNA synthesis. DNA synthesis was reversibly inhibited by aphidicolin (APH) in synchronized HeLa cells obtained by mitotic collection. TLCM directly measured intermitotic time intervals and thereby directly obtained the cell-cycle transit time distribution. In contrast, FCM measured time dependent changes in the fractions of cells in the cell-cycle phases from which the distribution of cells traversing a cell-cycle boundary, such as that between G₁ and S phase, was determined. Nevertheless, both methods provided equivalent measures of the cell-cycle transit time and its dispersion. However, TLCM apeared to provide a better measure of skewness of the transit time distribution than did FCM. Further, both methods were able to detect changes in the cell cycle transit on the order of 1 h or less. The TLCM data showed a greater precision (due to a larger number of data points) than that from FCM. However, FCM was able to directly measure changes in the transit of G₁ phase whereas TLCM would require two different experiments to make a similar determination. The results obtained in this study show that FCM can replace TLCM to study most aspects of cell-cycle progression.     

Correlation between timed up and go test and skeletal muscle tensiomyography in female nursing home residents

Objectives:Tensiomyography (TMG) derived contraction time (Tc) and amplitude (Dm) are related to muscle fibre composition and to muscle atrophy/tone, respectively. However, the link between mobility and TMG-derived skeletal muscle contractile properties in older persons is unknown. The aim of the study was to correlate lower limb skeletal muscle contractile properties with balance and mobility measures in senior female residents of retirement homes in Austria.Methods:Twenty-eight female participants (aged from 67-99 years) were included in measurements of contractile properties (TMG) of four skeletal muscles: vastus lateralis, vastus medialis, biceps femoris and gastrocnemius medialis. Their balance and mobility performance was measured using a timed up and go test (TUG).Results:Time needed to complete TUG is negatively correlated to biceps femoris (r= -0.490; p= 0.008), vastus lateralis (r= -0.414; p=0.028) and vastus medialis (r= -0.353; p=0.066) Dm and positively correlated to vastus lateralis Tc (r=0.456; p=0.015). Overall, vastus lateralis Tc and vastus medialis Dm explained 37% of TUG time variance.Conclusions:Our study demonstrates that TMG-derived quadriceps muscle contractile parameters are correlated with the balance and mobility function in female nursing home residents.     

Polyphenol Oxidase Activity and Phenolic Content Pattern During Shoot Development of Grape (Vitis vinifera L.) in Different Growing Seasons

The PPO activity and content of phenolic compounds were estimated during the different growing seasons and developmental age of shoots in seven grape genotypes. Both, the total phenol content and catecholase activity were found significantly affected by the growing season, developmental age of shoot and the genotype. But, season as well as age of shoot could not influence cresolase activity. Spring as season; 30 days of sprouting as age; Gold and Anab-e-Shahi as genotypes were found better in comparison to summer as season and 15 days of sprouting as age in respect to level of phenols and PPO activity.