Bimodal oxygen uptake in a freshwater air-breathing fish,Notopterus chitala

Measurements of bimodal oxygen uptake have been made in a freshwater air-breathing fish,Notopterus chitala at 29.0±1(S.D.)°C. xhe mean oxygen uptake from continuously flowing water without any access to air, was found to be 3.58±0.37 (S.E.) ml O₂ · h^?1 and 56.84+4.29 (S.E.) ml O₂ · kg^?1 · h^?1 for a fish weighing 66.92 + 11.27 (S.E.) g body weight. In still water with access to air, the mean oxygen uptake through the gills were recorded to be 2.49 ± 0.31 (S.E.) ml O₂ · h^?1 and 38.78 ± 1.92 (S.E.) ml O₂ · kg^?1 · h^?1 and through the accessory respiratory organs (swim-bladder) 6.04±0.87 (S.E.) ml O₂ · h^?1 and 92.32±2.91 (S.E.) ml O₂ · kg^?1 · h^?1 for a fish averaging 66.92±11.27 (S.E.) g. Out of the total oxygen uptake (131.10 ml O₂ · kg^?1 · h^?1), about 70% was obtained through the aerial route and the remainder 30% through the gills.     

Importance of sulfate,cysteine and methionine as precursors to felinine synthesis by domestic cats (Felis catus)

There is conflicting evidence in the literature on the utilization of cysteine and methionine as precursors to the urinary sulfur-containing amino acid felinine in cats. Three entire domestic short-haired male cats, housed individually in metabolism cages, were injected intraperitoneally with either [³⁵S]-sulfate, [³⁵S]-cysteine, or [³⁵S]-methionine. Daily urine samples were collected quantitatively for up to 9 days after injection. Each cat was injected once with each compound after observing an appropriate interval for [³⁵S] to be depleted between injections. All the urine samples were analysed for felinine content and total radioactivity. Felinine was isolated from each urine sample and analysed for radioactivity. No radioactivity was found in felinine from cats injected with [³⁵S]-sulfate. The mean (±S.E.M.) cumulative recovery of radioactivity in the urine of the [³⁵S]-sulfate injected cats was 90.6±6.1% after 4 days. The mean (±S.E.M.) cumulative incorporation rate of radioactivity into felinine by the cats receiving the [³⁵S]-cysteine and [³⁵S]-methionine were 11.6±1.6 and 8.6±0.6%, respectively, after 9 days. The mean (±S.E.M.) cumulative recoveries of radioactivity in the urine were 58.1±3.7 and 36.0±8.0%, respectively. Cysteine and methionine, but not sulfate, are precursors to felinine, with cysteine being a more quantitatively important precursor compared to methionine.     

The steady-state rate of ATP synthesis in the perfused rat heart measured by 31P NMR saturation transfer

The steady-state rate of ATP synthesis in the isolated, Langendorff-perfused rat heart was determined using a ³¹P NMR saturation transfer method. At 37°C and a perfusion pressure of 70 cm H₂O the value is 2.8 ± 0.3 (n=5 ± S.E.M.) μmol.s^?1. (g. dry wt.)^?1. The activity of creatine phosphokinase measured in the same experiments was 14.6 ± 1.0 μ mol.s^?1 .(g. dry wt.)^?1. From the rate of ATP synthesis and the separately measured oxygen consumption we calculated an apparent mitochondrial ADP:O ratio of 3.5 ± 0.8 in the intact tissue.     

Hydrogen peroxide release from human blood platelets

The release of hydrogen peroxide from human blood platelets after stimulation with particulate membrane-perturbing agents has been determined by fluorescence using scopoletin as the detecting agent. Platelet suspensions containing less than 1 polymorphonuclear leukocyte/10⁸ platelets showed a significant release of hydrogen peroxide (6.11 nmol/10⁹ platelets per 20 min, S.D., 0.26, n=9) after addition of zymosan or latex particles, compared to unstimulated platelets. The release of hydrogen peroxide was only observed when the scopoletin was added to the platelet suspensions during the stimulation. Any attempt to determine hydrogen peroxide release in the supernatant at the end of the incubation with zymosan or latex failed. A NADH-dependent production of hydrogen peroxide was observed by measuring the difference of oxygen uptake in the presence and absence of catalase (500 units), which was not inhibited by potassium cyanide (1 mM). By this method the NADH-dependent cyanide-insensitive peroxide production and release was 6.0 nmol/10⁹ platelets per 20 min from resting platelets (S.D., 2, n=6) vs. 15 nmol/10⁹ platelets per 20 min from stimulated platelets (S.D., 2, n=6).     

Adenine nucleotide metabolism of blood platelets IX. Time course of secretion and changes in energy metabolism in thrombin-treated platelets

Changes in the energy metabolism of washed human platelets were compared with the kinetics of secretion induced by thrombin (5 units/ml). A 50% decrease in the level of metabolic ATP (³H-labelled), which was essentially complete in 30 s, was matched in rate by adenine nucleotide secretion from storage in dense granules. Incubation of platelets with antimycin before thrombin addition increased the rate of fall in metabolic ATP, but did not affect the rate of adenine nucleotide secretion. β-N-Acetylglucosaminidase secretion, which was slower than adenine nucleotide secretion in control platelets, was noticeably inhibited by antimycin, confirming previous reports that different regulatory mechanisms exist for dense and α-granule secretion. The rates of rephosphorylation of metabolic ADP to ATP via glycolysis and oxidative phosphorylation were estimated by measuring lactate production and O₂ consumption in resting and thrombin-stimulated platelets and compared to the level of metabolic ATP (9–10 nmol/mg of platelet protein in the resting state). The rate of ATP production was stimulated at least two fold from 12 nmol to 24 nmol/min/mg within seconds of thrombin addition. This increased rate was maintained over the observed period of 5 min although the level of metabolic ATP had decreased to 4–5 nmol/mg within 30 s; the turnover of the remaining metabolic ATP thus increased four fold over the resting state although the actual stimulation of energy production was only two fold.     

Inhibitors of sterol synthesis. Hypocholesterolemic action of dietary 9α-Fluoro-5α-cholest-8(14)-en-3β-ol-15-one

9α-Fluoro-5α-cholest-8(14)-en-3β-ol-15-one, at a level of 0.15% in a laboratory chow diet, has been shown to have a significant hypocholesterolemic effect in normal rats. The mean serum cholesterol level (mg per 100 ml ± S.E.M.) decreased from 84.5 ± 1.5 to 53.3 ± 3.0, 54.1 ± 3.2, and 60.5 ± 2.6 after 5, 9, and 12 days, respectively, on the steroid-containing diet. The effects of the 9α-fluoro-15-ketosterol on serum cholesterol levels were significantly different from those of either ad libitum or pair-fed controls. The diet containing the steroid caused a significant decrease in food consumption which was associated with a decrease in the rate of gain in body weight.     

Changes in the oxygen consumption of cysts of Globodera rostochiensis associated with the hatching of juveniles

The oxygen consumption of single cysts (90–110 /tg dry wt) was measured with an oxygen electrode microrespirometer. The mean oxygen consumption of nine cysts after 7 days in tap-water, was 0–48 + 0–05 mm³ 0₂ mg dry wt^-1 h^-1. After transfer to potato root diffusate for 1 day the mean oxygen consumption of the same cysts showed a significant increase to 159±7% of the rate recorded before they were removed from water. After 3 and 7 days in diffusate the corresponding means were 131±9% and 127±12% respectively. Cysts that remained in water throughout the experiments did not show any significant change in their oxygen consumption from the rate recorded after 7 days. The initial increase in oxygen uptake after the addition of diffusate was shown not to be due to the presence of microorganisms. Comparison of hatching data with the changes in oxygen consumption of similar cysts after 24 h in diffusate suggests that the increased oxygen uptake cannot be attributed solely to locomotor activity of the juveniles during the hatching process. The increased rate of respiration may precede other known changes that follow after the juveniles within a cyst are stimulated to hatch.     

Potassium uptake by platelets from Down's syndrome and normal subjects

Potassium uptake was studied in Down's syndrome (D.S.) platelets to determine if the Na⁺/K⁺ ATPase mediated movement of this ion was decreased compared to normal platelets. Total uptake of ⁴²K was 1.58±0.16 μmoles/hr/10⁹ normal platelets but was decreased to 1.06±0.06 μmoles/hr/10⁹ D.S. platelets (p<.001). Na⁺/K⁺ ATPase mediated (ouabain sensitive) K⁺ uptake was 0.87±0.05 μmoles/hr/10⁹ normal platelets but only 0.54±0.04 μmoles/hr/10⁹ in D.S. platelets (p<.001). As the Na⁺/K⁺ ATPase mediated outward movement of Na⁺ is decreased in D.S. platelets, the present work demonstrates that bidirectional functional imparrment of the Na⁺/K⁺ ATPase pump is present in D.S. platelets.     

Adenine nucleotide metabolism of blood platelets. IX. Time course of secretion and changes in energy metabolism in thrombin-treated platelets.

Changes in the energy metabolism of washed human platelets were compared with the kinetics of secretion induced by thrombin (5 units/ml). A 50% decrease in the level of metabolic ATP (3H-labelled), which was essentially complete in 30s, was matched in rate by adenine nucleotide secretion from storage in dense granules. Incubation of platelets with antimycin before thrombin addition increased the rate of fall in metabolic ATP, but did not affect the rate of adenine nucleotide secretion. beta-N-Acetylglucosaminidase secretion, which was slower than adenine nucleotide secretion in control platelets, was noticeably inhibited by antimycin, confirming previous reports that different regulatory mechanisms exist for dense and alpha-granule secretion. The rates of rephosphorylation of metabolic ADP to ATP via glycolysis and oxidative phosphorylation were estimated by measuring lactate production and O2 consumption in resting and thrombin-stimulated platelets and compared to the level of metabolic ATP (9-10 nmol/mg of platelet protein in the resting state). The rate of ATP production was stimulated at least two fold from 12 nmol to 24 nmol/min/mg within seconds of thrombin addition. This increased rate was maintained over the observed period of 5 min although the level of metabolic ATP had decreased to 4-5 nmol/mg within 30 s; the turnover of the remaining metabolic ATP thus increased four fold over the resting state although the actual stimulation of energy production was only two fold.     

Increase in respiratory rate during feeding in larvae of the armyworm, Spodoptera exempta

Oxygen consumption was measured in fifth and sixth instar larvae of Spodoptera exempta (Walker) (Lepidoptera, Noctuidae) at 25d?C using Warburg manometry. The mean rate of oxygen consumption while feeding on maize or sorghum leaves was approximately twice that at rest. The increment in oxygen consumption attributable to feeding was 583±207 μlg-¹ h-^l (mean±95% confidence limits) or, for maize, 6.1±3.5 μl O₂ per mg of leaf eaten.     

Effects of 2-tetradecylglycidic acid on rat platelet energy metabolism and aggregation.

We investigated the role of energy supplied by long-chain fatty acid oxidation in rat platelet function. Inhibition of the mitochondrial uptake of long-chain fatty acids was achieved by treating rats with 2-tetradecylglycidic acid (TDGA), a potent inhibitor of the overt form of carnitine palmitoyltransferase (CPT-I). The maximum aggregation rate (MAR), CPT-I activity, lactate production, oxygen consumption and adenine nucleotide content of isolated rat platelets were then studied in vitro. 4 h after the in vivo administration of TDGA, the CPT-I activity in saponin-permeabilized platelets was nearly completely inhibited along with a significant reduction in the MAR induced by ADP, thrombin and ionophore A23187. The ATP level, adenylate energy charge (ATP + 1/2 ADP)/(ATP + ADP + AMP) and ATP/ADP ratio in the platelet cytoplasmic pool were also reduced. Platelets from TDGA-treated rats showed lower oxygen consumption rates in both the basal respiratory and oxygen burst states. These results indicate that mitochondrial long-chain fatty acid oxidation coupled to oxidative phosphorylation is an important energy source in rat platelets and is probably involved in the maintenance of platelet function. Enhanced in vitro lactate production in platelets from TDGA-treated rats may have resulted from a compensatory increase in glycolysis which only partly compensated for impaired long-chain fatty acid oxidation.     

Predatory Filter-Feeding in Fairy Shrimps: Functional Response of Streptocephalus proboscideus (Crustacea: Anostraca) Fed Anuraeopsis fissa (Rotifera)

Four size classes of both sexes of laboratory-cultured Streptocephalus proboscideus (post-metanauplii 4.7±0.4; juvenile virgins 8.7±0.7; adults I 13.8±0.9, and adults II 22.07±1.1 mm) were fed five concentrations (20 to 320 ml⁻¹) of Anuraeopsis fissa, or six concentrations (20 to 640 ml⁻¹) in adults I and adults II, for 30 minutes. Post-metanauplii consumed at maximum 66±9 rotifers ind.⁻¹ min.⁻¹ (mean±S.D.) while the largest adult females maximally ingested 347±37 rotifers min.⁻¹. Regardless of predator size and sex, prey consumption was dependent on prey density. Functional response curves either plateaued or declined at 320 prey ml⁻¹ in post-metanauplii, juveniles and adults I, and at 640 ml⁻¹ in adults II. Females consumed c. 40% more prey than males. On a daily basis, adult II females consumed up to 1.05 mg rotifer dry weight (10% of their own body weight) while post-metanauplii consumed up to 0.2 mg DW (100% of their body weight). Intermediate stages had intermediate consumption rates. Filtration rates indicated that a fully grown S. proboscideus may filter as much as 2 1 of water per day, suggesting that fairy shrimps, in their natural environment, may often be food-limited.     

Quantification of energy consumption in platelets during thrombin-induced aggregation and secretion. Tight coupling between platelet responses and the increment in energy consumption.

The involvement of metabolic energy in platelet responses was investigated by measuring the energy consumption during aggregation and secretion from dense, alpha- and acid-hydrolase-containing granules. Gel-filtered human platelets were stimulated with different amounts of thrombin (0.05-5.0 units X ml-1). At various stages during aggregation and secretion the energy consumption was measured from the changes in metabolic ATP and ADP following abrupt arrest of ATP resynthesis. Stimulation with 5 units of thrombin X ml-1 increased the energy consumption from 6.2 +/- 0.9 to 17.8 +/- 0.4 mumol of ATPeq. X min-1 X (10(11) platelets)-1 during the first 15 s. It decreased thereafter and returned to values found in resting cells after about 30 s. With 0.05 unit of thrombin X ml-1, the energy consumption accelerated more slowly and took at least 3 min before it normalized. A strong positive correlation was found between the velocities of the three secretion responses and the concurrent energy consumption (a) at different stages of the responses induced by a given dose of thrombin, and (b) at different secretion velocities initiated by different amounts of thrombin. When, at different stages of the responses, the extent of secretion was compared with the amount of energy that had been consumed, a strong linear correlation was found with the increment in energy consumption but not with the total energy consumption. This correlation was independent of the concentration of thrombin and indicated that complete secretion from dense, alpha- and acid-hydrolase-containing granules was paralleled by an increment of 4.0, 6.5 and 6.7 mumol of ATPeq. X (10(11) platelets)-1, respectively. An energy cost of 0.7 mumol of ATPeq. X (10(11) platelets)-1 was calculated for separate dense-granule secretion, whereas the combined alpha- and acid-hydrolase granule secretion required 5.3 mumol of ATPeq. X (10(11) platelets)-1. There was no correlation between energy consumption and optical aggregation. In contrast, the rate of single platelet disappearance, which is a measure for the early formation of small aggregates, correlated closely with the rate of energy consumption. Compared with secretion, however, the energy requirement of single platelet disappearance was minor, since 2mM-EDTA completely prevented this response but decreased the energy consumption only slightly. An increase of 0.5-1.0 mumol of ATPeq. X (10(11) platelets)-1 was seen before single platelet disappearance and the three secretion responses were initiated, indicating an increase in energy consuming processes that preceded these responses.(ABSTRACT TRUNCATED AT 400 WORDS)     

Technetium-99m-labeled platelets: Comparison of labeling with a new lipid-soluble Sn(II)-mercaptopyridine-N-oxide and 99mTc-HMPAO

Platelets pretinned with a neutral Sn(II)-2-mercaptopyridme-N-oxide (SN-MPO) were labeled with ^99mTc and compared to those labeled with ^99mTc-HMPAO. The conditions of labeling platelets, e.g. concentrations of platelets and Sn(II)-MPO, ^99mTc in ACD-saline or ACD-plasma media, pH and incubation time, were optimized using canine platelets. Moderate labeling efficiency was obtained with 20 μg of tin(II) chloride and 30 min incubation with Sn-MPO and pertechnetate. The viability of labeled platelets was determined by platelet recovery and platelet survival times in Beagle dogs. The labeling efficiency with platelets from 43 mL of blood was 62.8 ± 7.6%. The platelet recovery was 35.7 ± 5.0% and exponential survival time was 34.6 ± 3.1 h compared to 43.3 ± 12.0% and 29.5 ± 3.3 h for ^99mTc-HMPAO-labeled platelets. These values were significantly (P < 0.01) lower than ¹¹¹In-labeled platelets. Biodistribution in dogs indicates lower retention in blood, spleen and liver after some initial ^99mTc excretion in urine. The platelet deposition with ^99mTc platelets (Sn-MPO method) on polyurethane angio-catheters was similar to ^99mTc-HMPAO-labeled platelets. This study indicates that the platelets could be successfully labeled with pertechnetate in a cost-effective manner for the evaluation of thromboembolic complications.     

Inhibitors of sterol synthesis. Hypocholesterolemic action of dietary 5α-cholest-8(14)-en-3β-ol-15-one in rats and mice

5α-Cholest-8(14)-en-3β-ol-15-one, at a level of 0.1% in a low cholesterol diet has been shown to have a profound hypocholesterolemic effect in rats. In one experiment the mean serum cholesterol level (mg per 100 ml ± S.E.M.) decreased from 71.2 ± 0.9 to 36.9 ± 3.3 after 7 days on the diet. In a second experiment the mean serum cholesterol value decreased from 86.4 ± 1.2 to 33.4 ± 3.9 after 8 days on the ketone-containing diet. The effects of the 15-ketosterol on serum cholesterol levels were significantly (p<0.001) different from those of eitheir ad libidum or pair-fed controls. The diet containing the ketone caused a significant decrease in food consumption and a slight decrease in body weight (10.2% and 3.1% in the two experiments). The ketone, at a level of 0.2% in the diet, caused a marked decrease in plasma cholesterol levels in mice. After 8 days of treatment the plasma cholesterol value (mg per 100 ml ± S.E.M.) of the treated mice was 35.8 ± 3.6 while that of pair-fed control animals was 114.4 ± 3.4.     

Respiration rates of subitaneous eggs from a marine calanoid copepod: monitored by nanorespirometry

The oxygen consumption rate during embryogenesis of Acartia tonsa subitaneous eggs were measured at different temperatures (10, 15, 17, 21, 24 and 28°C) with nanorespirometry. The oxygen consumption was constant during the embryogenesis but increased rapidly at hatching time. The mean ± SD oxygen consumption rate increased exponentially with temperature and ranged from 0.09 ± 0.04 (10°C) to 0.54 ± 0.09 nmol O₂ egg⁻¹ h⁻¹ (28°C). The mean ± SD Q₁₀-value was 2.51 ± 0.15. Calculations of energy consumption during embryogenesis ranged from 1.86 to 18.28 mJ depending on temperature and development time. We conclude that the effect of temperature on oxygen consumption rate was far less important than the prolonged development time when calculating the energy consumed during embryogenesis.     

Effect of Erucic Acid on Platelets in Patients with Adrenoleukodystrophy

In a clinical trial for the management of adrenoleukodystrophy, we analyzed the effect of erucic acid (a component of Lorenzo's oil) on platelet number, fatty acid composition, and function. Analysis of variance was performed to compare platelet counts before starting treatment with Lorenzo's oil and at 6 and 12 months. We measured platelet fatty acid composition in subjects and control patients and correlated these values with their platelet counts using discriminant analysis. After 6 months, the mean platelet count decreased from 247,000/mm³to 169,000/mm³(±1 standard deviation 58,000,n= 39),P< 0.0001 compared to 18 subjects on a control diet having a mean baseline platelet count of 259,000/mm³(±1 standard deviation 67,000,n= 19) and at 6 months 267,000/mm³(±1 standard deviation 71,000). We found atP< 0.05 that the platelet counts showed a strong inverse relationship with erucic acid levels and other omega 9 fatty acids that form from the administration of the erucic acid component of Lorenzo's oil. Morphologic and platelet sizing measurements suggest that the physical properties of platelets may also be affected by erucic acid. Our studies show that the ingestion of erucic acid affects platelet biology. This indicates that platelet counts and properties are influenced by monounsaturated fatty acids, in addition to the well-known effects of polyunsaturated fatty acids. In areas of the world where erucic acid is widely ingested, the biology of platelets in these populations may be affected.     

Epidermal growth factor receptors in fetal and maternal rabbit lung

The pattern of morphologic and functional development of lung during intrauterine period is influenced by several endogenous compounds. Recently Epidermal Growth Factor (EGF), when administered in vivo, has been shown to accelerate pulmonary maturation in fetal rabbit and sheep. We sought evidence for EGF receptor occurrence in fetal and maternal rabbit lung plasma membranes. The percent specific binding (mean ± S.E.M.) (125-I) EGF to LPM in the mother (n=5) and the fetus at term (n=7) was 1.08 ± 0.08 and 2.25 ± 0.12 per 175 μg of LPM protein respectively. The number of receptor sites per mg of LPM protein in the mother were significantly less than that in the fetus (44 ± 11 and 250 ± 24 × 10^?10, p < 0.001) with no apparent differences in Kd (2.10 ± 0.39 and 2.47 ± 0.24 × 10⁹). Presence of high affinity receptors for EGF in fetal and maternal lung plasma membranes suggests a direct role of EGF in fetal lung maturation.     

Addition of both platelets and thrombin in combination accelerates tumor cells to adhere to endothelial cells In vitro

Summary Platelets and coagulation are involved in the pathogenesis of blood-borne metastases. The aim of this study is to obtain more information about the mechanisms involved in the initial adhesion of tumor cells to endothelial cells. In short term experiments with tumor cells, suspended in the medium of cultured endothelial cells, we tested whether addition of both platelets and thrombin cause more tumor cell adhesion to endothelial cells, than when either platelets or thrombin are acting alone. HeLa cells or HT29 cells, prelabeled with radioactive ⁵¹Cr, human platelets, and thrombin were added to human endothelial cell cultures. Following 15 min of shaking at 37° C, the percentage of tumor cell adhesion was calculated. The percentages of adhering tumor cells with the presence of both platelets and thrombin were greatly increased compared to controls. Addition of hirudin 2 min before thrombin lowered the adhesion percentage of tumor cells. Hirudin added immediately before and 2 min after thrombin gave only minor effects. When the endothelium was treated with superoxide dismutase, catalase, and mannitol, the adhesion of tumor cells was lowered with catalase and superoxide dismutase. The cause of tumor cell-endothelial cell interaction is probably complex. Our results show that activated platelets enhance the tumor cell adhesion, and that generation of active oxygen species may be important in the initial phase of the interaction.     

The effect of time of day and exercise on platelet functions and platelet–neutrophil aggregates in healthy male subjects

Platelet activation state changes by exercise. The effect of exercise time on platelet activation state and formation of platelet–neutrophil aggregates are not known yet. In this study the effect of exercise and time of day were examined on platelet activity with platelet–neutrophil aggregates. Ten moderately active males aged 27± 1.63 (mean±S.D.) years completed sub-maximal (70% VO_2max) exercise trials for 30 min. Blood pressure (BP) was recorded. Venous blood samples were obtained at rest, immediately post-exercise and after 30 min of recovery. Whole blood was analysed for haematocrit (Hct), haemoglobin (Hb), platelet count (PC), mean platelet count (MPV) and platelet aggregation (PA). Platelet–neutrophil aggregates and beta-thromboglobulin (β-TG) levels were assayed. Platelet count showed significant increase after morning exercise ((236± 32)×10⁹ l⁻¹ versus (202± 34)×10⁹ l⁻¹ baseline, p < 0.05). Exercise resulted in significantly lower MPV after the evening exercise (9.16± 0.5 fl versus 9.65± 0.36 fl, p < 0.05). Platelet aggregation by adenosine diphosphate (ADP) decreased after morning exercise and the recovery aggregation levels were significantly different at two different times of the day (68± 20% a.m. versus 80± 12% p.m., p < 0.05). It was also showed that platelet–neutrophil aggregates increased significantly from baseline after both exercises. Exercise-induced platelet–neutrophil aggregates were higher in the evening (10.7± 1.3% p.m. versus 6.4± 1.8% a.m., p < 0.0001). It is therefore concluded that besides platelet–platelet aggregation, exercise can cause platelet– neutrophil aggregates. In addition, time of day has an effect on platelet activation related events. Circadian variations of physiological parameters may have an effect on thrombus formation by platelet activation. (Mol Cell Biochem xxx: 119–124, 2005)