Microspectrophotometric determination of the haemoglobin oxygen saturation in haemolyzed arterialized capillary blood

A description is given of a rapid spectrophotometric micromethod of determining the oxygen saturation in arterialized capillary blood. During sampling, the blood was haemolyzed in a glass capillary with the aid of the haemolytic agent Sterox SE. Extinctions were measured at 795 nm and 655 nm in a cuvette made up of slides (d = 1 mm). A single determination is sufficiently exact. Capillary blood from the arterialized earlobe was found to be an adequate substitute for blood from an artery. This method showed good agreement with the haemoreflector method

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LEIDSSTELSELOPLADEN-RUG0

Comparison of Four Commercially Available cAMP Kits

Peer Reviewe

Effects of Individual Control of pH and Hypoxia in Chondrocyte Culture

Effects of oxygen tension (pO(2)) and pH on gene and protein expression and metabolic activity of human chondrocytes were independently assessed. Chondrocytes were cultured under a range of pH (6.4-7.4) and different pO(2) (5 and 20%) during 5 days in a bioreactor. Effects on gene expression, DNA content, protein expression, and metabolic activity were determined. Linear regression analysis showed that gene expression of type I collagen (COL1), S0X9, and VEGF is significantly lower at acidic pH, while expression of aggrecan, type II collagen, and HIF1A is pH-independent. Higher protein levels of VEGF were found under low pO(2). Acidic pH severely lowered VEGF release into medium, glucose consumption, and lactate production. Extracellular pH proved to more potently influence cell function than oxygen tension, the latter showing down-regulation of COL1 gene expression and up-regulation of VEGF protein under hypoxia. Hypoxic culture inhibits COL1 mRNA expression pH-dependently, while expression of SOX9 is largely hypoxia independent, but pH dependent. Expression of HIF1A and VEGF revealed divergent pH dependencies. Subtle fluctuations in extracellular pH and oxygen tension clearly influence chondrocyte metabolism and marker expression. Sophisticated pH and oxygen control not only allows study of (patho)physiological changes, but also opens new venues in cartilage tissue engineering. (C) 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:537-545, 201