Automated measurement of lactate dehydrogenase, alkaline phosphatase and gamma-glutamyltransferase in urines: an alternative to the manual procedure.

A sensitive and precise automated assay of urinary lactate dehydrogenase (EC 1.1.1.27), alkaline phosphatase (EC 3.1.3.1) and gamma-glutamyltransferase (EC 2.3.2.2) is described. For this purpose, we used a BM/Hitachi System 704 model and reagents for automated analysis of serum enzymes from Boehringer Mannheim. However, the schedules of enzyme chemistry parameters recorded by the autoanalyzer and the spectrophotometric calibration are reprogrammed to meet requirements deriving from urine adoption and to optimize the enzyme assay in this unusual medium.     

Effect of calcium concentration on survival, proliferation and activities of alkaline phosphatase, 5'-nucleotidase, gamma-glutamyltransferase and lactate dehydrogenase of adult rat hepatocytes cultured in serum-free medium.

Mature rat hepatocytes were cultured on collagen coated dishes in serum-free alpha-modified Eagle's minimum essential medium containing 0.1 microM insulin, 0.1 microM dexamethasone, 10 mM pyruvate and Ca2+ at concentrations of 0-2 mM. Survival of nondivided cells was best in medium containing 2 mM Ca2+. Proliferation during 5-day culture was greatest with 0.4 mM Ca2+, but DNA synthesis was scarcely affected by the concentration of Ca2+. Both the activities of alkaline phosphatase, 5'-nucleotidase, gamma-glutamyltransferase and lactate dehydrogenase and the number of cell nuclei of cultures in 0.1 mM and 2 mM Ca2+ media were assayed over a 5-day period, and their activities were calculated as enzyme activities per unit number of cell nuclei. Alkaline phosphatase activity increased rapidly during the first day of culture in both media, and its activity in 0.1 mM medium was higher than that in 2 mM medium after culture for 3 days. The activity of 5'-nucleotidase became higher in 0.1 mM medium than in 2 mM medium from day 2 and was maximal on day 3 in both media. gamma-Glutamyltransferase activity increased and lactate dehydrogenase activity decreased with time in culture, both activities showing no appreciable difference in the two media.     

Influence of L-thyroxine upon enzymatic activity in the renal tubular epithelium of the rat under normal conditions and in mercury-induced lesions. I. Histochemical studies of alkaline phosphatase, acid phosphatase, adenosine- tri-phosphatase and leucine-aminopeptidase.

HgC12-induced renal tubular lesions in the rat present histochemically with a transitory decrease of alkaline phosphatase, adenosinetriphosphatase (ATPase), and leucine-aminopeptidase activity. The toxic alterations of enzyme activity were more pronounced in the pars recta of the proximal tubule and in the loop of Henle, as compared with the tubulus contortus I. L-thyroxine treatment leads to an accelerated reversal of that enzymatic defect, followinga characteristic pattern, and to a differentiating increase of acid phosphatase and ATPase activity in certain parts of the normal renal tubule. The observations are discussed with reference to the specific mode of action of sublimate and l-thyroxine upon the tubular enzymes and to the well-known metabolic and functional influences of thyroid hormone on the kidney.     

An electron microscopic,enzyme cytochemical study on the localization of lactate dehydrogenase (LDH) in osteoclasts and peritoneal macrophages of the rat and its implication for the process of bone resorption and the origin of osteoclasts

Summary LDH is localized along various intracytoplasmatic membranes of osteoclasts. Macrophages show membrane-bound LDH only after phagocytosis of calcium hydroxylapatite, the main mineral constituent of bone. The localization of LDH in these macrophages is almost the same as in osteoclasts. The significance of this finding, and its possible implication in the process of bone resorption and the origin of osteoclasts are discussed. Present Adress: Department of Oral Microbiology, School of Dentistry, Vrije Universiteit, P.O. Box 7161, 1007 MC Amsterdam, The Netherlands     

On the causes of interspecific differences in the growth-irradiance relationship for phytoplankton. Part I. A comparative study of the growth-irradiance relationship of three marine phytoplankton species: Skeletonema costatum, Olisthodiscus luteus and Gonyaulax tamarensis

Three marine phytoplankton species (Skeletonema costatum, Olisthodiscusluteus andGonyaulax tamarensis) were grown in batch culturesat 15°C and a 14:10 L:D cycle at irradiance levels rangingfrom 5 to 450 µEinst m^–2 s^–1. At each irradiance,during exponential growth, concurrent measurements were madeof cell division, carbon-specific growth rate, photosyntheticperformance (both O₂ and POC production), dark respiration,and cellular composition in terms of C, N and chlorophyll a.The results indicate that the three species were similar withrespect to chemical composition, C:N (atomic) = 6.9 ±0.4, photo-synthetic quotient, 1.43 ± 0.09, and photosyntheticefficiency, 2.3 ±0.1 x 10^–3 µmol O₂ (µgChl a)^–1 h^–1 (µEinst m^–2 s^–1)^–1.Differences in maximum growth rate varied as the –0.24power of cell carbon. Differences in growth efficiency, werebest explained by a power function of Chl a:C at µ = 0.Compensation intensities, ranged from 1.1 µEinst m^–2s^–1 for S. costatum to 35 forG. tamarensis and were foundto be a linear function of the maintenance respiration rate.The results indicate that interspecific differences in the µ–Irelationship can be adequately explained in terms of just threeparameters: cell carbon at maximum growth rate, the C:Chl aratio (at the limit as growth approaches zero) and the respirationrate at zero growth rate. A light-limited algal growth modelbased on these results gave an excellent fit to the experimentalµ–I curves and explained 97% of the observed interspecificvariability. ¹Present address: Lamont-Doherty Geological Observatory Columbiaof University, Palisades, NY 10964, USA