Accumulation of cocaine in maternal and fetal hair; the dose response curve.

Cocaine and its major metabolites are incorporated into hair during the growth of the shaft and stay there for the whole life of the hair. Cocaine crosses the placenta and its metabolites for example Benzoylecgonine (BZ), have been found in neonatal urine, meconium and hair. In order to utilize hair measurements of cocaine as a biological marker of systemic exposure, we conducted both animal and human investigations on the dose response characteristics of this phenomenon. Our data suggest that both maternal and fetal accumulation of cocaine and its metabolite follow a linear pattern within the clinically used doses. Similarly, a good correlation was observed in animals between maternal dose and fetal hair accumulation.     

Vanadate inhibits saltatory organelle movement in a permeabilized cell model

A method has been developed for sustaining saltatory organelle movement in permeabilized cells. Fibroblasts are permeabilized using the nonionic detergent, Brij 58, with a 2-step procedure modified from the methods of Cande [1–4]. Saltatory movement continues for 20–40 min in the permeabilized cells, provided that ATP is present in the lysis medium, although the saltations are less frequent and slower than those seen before detergent treatment. Vanadate rapidly and reversibly inhibits saltatory movement in the permeabilized cells. Inhibition by vanadate suggests that a dynein-like molecule may be involved in the mechanism of saltatory movement.     

Utilization of Citrate, Acetylcarnitine, Acetate, Pyruvate and Glucose for the Synthesis of Acetylcholine in Rat Brain Slices

Slices of rat caudate nuclei were incubated in saline media containing choline, paraoxon, unlabelled glucose, and [1,5-14C] citrate, [1-14C-acetyl]carnitine, [1-14C]acetate, [2-14C]pyruvate, or [U-14C]glucose. The synthesis of acetyl-labelled acetylcholine (ACh) was compared with the total synthesis of ACh. When related to the utilization of unlabelled glucose (responsible for the formation of unlabelled ACh), the utilization of labelled substrates for the synthesis of the acetyl moiety of ACh was found to decrease in the following order: [2-14C]pyruvate greater than [U-14C]glucose greater than [1-14C-acetyl]carnitine greater than [1,5-14C]citrate greater than [1-14C]acetate. The utilization of [1,5-14C]citrate and [1-14C]acetate for the synthesis of [14C]ACh was low, although it was apparent from the formation of 14CO2 and 14C-labelled lipid that the substrates entered the cells and were metabolized. The utilization of [1,5-14C]citrate for the synthesis of [14C]ACh was higher when the incubation was performed in a medium without calcium (with EGTA); that of glucose did not change, whereas the utilization of other substrates for the synthesis of ACh decreased. The results indicate that earlier (indirect) evidence led to an underestimation of acetylcarnitine as a potential source of acetyl groups for the synthesis of ACh in mammalian brian; they do not support (but do not disprove) the view that citrate is the main carrier of acetyl groups from the intramitochondrial acetyl-CoA to the extramitochondrial space in cerebral cholinergic neurons.     

Rat alveolar macrophages require NADPH for superoxide production in the respiratory burst. Effect of NADPH depletion by paraquat

Alveolar macrophages can be stimulated by concanavalin A to produce extracellular superoxide. Conflicting opinions exist, however, concerning the relative importance of the oxidation of either NADPH or NADH in the generation of (Formula: see text) by surface membrane-stimulated phagocytic cells. Alveolar macrophages were obtained from adult male rats by lavage with phosphate-buffered saline. Cells (approximately 10(6)/ml) were incubated in Krebs-Ringer phosphate 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer and ferricytochrome c for 15 min at 37 degrees C before addition of concanavalin A. Release of (Formula: see text) was detected as the difference in cytochrome c reduction, followed at 550 nm, in the absence and presence of superoxide dismutase. Superoxide production by concanavalin A-stimulated alveolar macrophages was markedly increased in the presence of glucose but fructose, lactate, and pyruvate were without effect. Paraquat (methylviologen), an oxidation-reduction dye, significantly reduced concanavalin A-stimulated (Formula: see text) production when incubated at 1 mM with alveolar macrophages in the absence of glucose. The effect of paraquat was reversed by glucose, but fructose, lactate, and pyruvate could not reverse paraquat inhibition. Paraquat enhanced oxidation of NADPH (but not NADH) by cell supernatant and increased pentose phosphate shunt activity in resting macrophages, but did not affect mitochondrial respiration or ATP content of alveolar macrophages. These results suggest that paraquat is able to specifically deplete NADPH in alveolar macrophages while not affecting NADH or ATP. Our conclusion is that NADPH is essential for the production of (Formula: see text) by concanavalin A-stimulated alveolar macrophages.     

Dihydroorotate-dependent superoxide production in rat brain and liver. A function of the primary dehydrogenase.

Dihydroorotate dehydrogenase in rat brain mitochondria is capable of producing superoxide. The presence of a superoxide dismutase activity in brain mitochondria, similar to that found in mitochondria from chicken liver, suggests that production of superoxide may occur in vivo. Formation of superoxide is not dependent upon reduction of cytochrome b, rather, superoxide production is competitive with cytochrome b reduction. Phenazine methosulfate apparently competes with both oxygen (superoxide production) and cytochrome b as an electron carrier but does not enhance reduction of dichlorophenolindophenol or cytochrome c.     

Quantifying the damage of red deer (Cervus elaphus) grazing on grassland production in southeastern Slovenia

The influence of red deer (Cervus elaphus) grazing on grassland production for forage conservation at the forest border during the vegetation period was studied on three locations (Mala gora, Cvišlerji, and Mačkovec) in the Kočevje region (SE Slovenia). The experiment lasted from the 25th of March until the 8th of October 2002. Portable cages were used to exclude red deer from grazing the herbage. At four sampling dates in the season, herbage air dry matter (DM) yield was measured at three different observations (cage-protected plot, cage-protected plot only two to three weeks before sampling date, otherwise freely grazed (removed), and unprotected plot). The results from the experiment showed that red deer grazed on grassland through the entire season and that the regeneration capability of sward was the highest in summer, middle in spring and smallest in autumn. On unprotected plots, an average reduction of 50% of herbage DM yield was found with the most damaged sites also up to 80% reduction.