The acute effect of 30 min of moderate exercise on high density lipoprotein cholesterol in untrained middle-aged men

Fifteen middle-aged, untrained (defined as no regular exercise) men (mean age 49.9 years, range 42-67) cycled on a cycle ergometer at 50 rpm for 30 min at an intensity producing 60% predicted maximum heart rate [(fc,max), where fc,max = 220 - age]. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride (Tg) concentrations were measured from fasting fingertip capillary blood samples collected at rest, after 15 and 30 min of exercise, and at 15 min post-exercise. The mean HDL-C level increased significantly from the resting level of 0.85 mmol.l-1 to 0.97 mmol.l-1 (P < 0.05) after 15 min of exercise, increased further to 1.08 mmol.l-1 (P < 0.01) after 30 min of exercise and remained elevated at 1.07 mmol.l-1 (P < 0.01) at 15 min post-exercise. These increases represented changes above the mean resting level of 14.1%, 27.1% and 25.9% respectively. The HDL-C/LDL-C ratio increased significantly from a resting ratio of 0.20 to 0.26 after 30 min of exercise (P < 0.01) and to 0.24 at 15 min post-exercise (P < 0.05). The mean Tg level increased significantly from a resting level of 0.88 mmol.l-1 to 1.05 mmol.l-1 after 15 min, and to 1.06 mmol.l-1 after 30 min of exercise (P < 0.05 at each time). The TC/HDL-C ratio decreased significantly (P = 0.05) after 30 min of exercise and at 15 min post-exercise by 18.8% and 14%, respectively. No significant changes were observed in the levels of TC or LDL-C over time.(ABSTRACT TRUNCATED AT 250 WORDS)     

Morphological differentiation of endothelial cells co-cultured with astrocytes on type-I or type-IV collagen

Summary In this study bovine aortic endothelial cells were co-cultured with astrocytes from fetal Wistar Kyoto rats. Endothelial cells growing on type-I collagen, development. Although some cells appeared to be mature, horseradish peroxidase penetrated within 1 min of incubation through the intercellular junctions of these endothelial elements maintained on type-I collagen. In contrast, endothelial cells on type-IV collagen, co-cultured with astrocytes, were well developed; their intercellular junctions were well established, and plasmalemmal vesicles reduced in number. As a result, horseradish peroxidase was unable to penetrate through the endothelial cells grown on type-IV collagen and co-cultured with astrocytes because of the reduced extent of the junctional and vesicular transport. These findings reveal that (1) type-IV collagen is essential for the differentiation of endothelial cells, (2) endothelial cell-astrocyte interactions occur during co-culture, and (3) endothelial permeability depends on astrocyte-produced factors, in addition to type-IV collagen.     

Cholesterol alterations in young dystrophic mice

Cholesterol and cholesteryl ester concentrations and cholesteryl ester fatty acid substituents have been measured during the first 10 weeks of life in tissues of normal and dystrophic mice. In normal Swiss and 129ReJ(+/?) mice the concentrations of both cholesterol and cholesteryl esters remain essentially constant in liver, increase in brain and fall sharply in both thigh (mixed fiber type muscles) and chest muscles (predominantly slow oxidative muscles) over this period. In all cases the concentration of free cholesterol exceeds that of esterified cholesterol. In dystrophic mice, similar patterns are found in brain and liver. In both thigh and chest muscles, however, the developmental pattern is significantly different. After an initial decrease the concentrations of cholesterol and cholesteryl esters increase rapidly with the largest increase occurring in the concentration of cholesteryl esters which by 10 weeks of age exceeds the concentration of cholesterol in chest muscle. During the same period the pattern of esterified fatty acids changes gradually in dystrophic tissues towards an increasing ratio of unsaturated/saturated fatty acids. By 10 weeks of age this ratio is significantly higher in dystrophic tissues than normal in all tissues tested.     

Regulation of polyphosphate metabolism in Acinetobacter strain 210A grown in carbon- and phosphate-limited continuous cultures

The response of Acinetobacter strain 210A to low phosphate concentrations was investigated in P- or C-limited chemostat cultures. The organism accumulated poly--hydroxybutyric acid under P-deprivation, at phosphate concentrations ranging from 0.1 to 0.7 mM. The amount of biomass was proportional to the phosphate concentration in the medium and no polyphosphate was formed. When shifting a culture from P- to C-limitation phosphate was accumulated as polyphosphate. No poly--hydroxybutyrate could be detected in these cells. The amount of polyphosphate in the cell showed a hysteresis. When cultures were shifted from low to high phosphate concentrations, polyphosphate reached a maximum of about 60 mg P per gram of dry weight at about 3 times excess phosphate (ca. 2.5 mM P_i). It decreased to 45 mg P per gram dry weight at approximately 5 times the phosphate needed for growth (ca. 3.5 mM P_i). In the reverse case (high to low) polyphosphate did never exceed 45 mg P per gram dry weight. The specific activities of alkaline phosphatase and the phosphate uptake system were induced at residual P_i concentrations below the detection limit (<10 M). The specific uptake rate followed also a hysteresis. The specific activities of polyphosphatase and polyphosphate: AMP phosphotransferase increased when polyphosphate formation was possible.Abbreviations HPP High polymeric polyphosphates - PHB Poly--hydroxybutyric acid - PP_n Polyphosphate - PQQ Pyrrolo-quinoline quinone - U 1 mol product formed · min^-1     

Correlation between manganese-deficiency,loss of respiratory chain complex I activity and citric acid production in Aspergillus niger

The correlation between manganese deficiency, loss of mitochondrial respiratory chain NADH: ubiquinone oxidoreductase (complex I) activity and citric acid overproduction in the Aspergillus niger strain B 60 was analysed. With increasing manganese-supplementation of the production medium the loss of complex I activity and the production of citric acid was reduced. Addition of manganese during growth stopped further loss of complex I activity and further increase of citric acid production. A possible causality between complex I deficiency and citric acid overproduction is discussed.     

Long term regulation of nucleoside transport by thyroid hormone (T3) in cultured chromaffin cells

The adenosine transport in cultured chromaffin cells was increased by the presence of triiodo-l-thyronine (T₃) throughout the prolonged period studied. The V_max values of this transport obtained in absence and presence of 1 M T₃ were 36.21±2.1 and 44.17±3.5 (means±SD) pmol/10⁶cells/min respectively for 26 hours incubation-time with the hormone. The K_m values were not significantly modified. The number of adenosine transporters in cultured chromaffin cells, measured by [³H]nitrobenzylthioinosine (NBTI) binding, was increased by 1 M T₃ for 26 hours incubation-time. The values of binding sites per cell were 33,500±3,000 and 40,153±3,700 in absence and presence of T₃ respectively, without changing the K_d constant. When the transport studies were carried out in presence of cycloheximide, an inhibitor of protein synthesis, the adenosine transport capacity decreased with a half-life values of 23.9±2.8 and 24.3±2.1 hours both in the presence or absence of T₃ respectively. When cells were incubated in the presence of both T₃ and cycloheximide, not only the activatory effect of T₃ was completely abolished but also adenosine transport was decreased to the same extent as with cycloheximide alone. These results indicated that T₃ activation of adenosine transport in chromaffin cells required the protein-synthesizing mechanism.     

On the activity of γ-aminobutyric acid and glutamate transporters in chick embryonic neurons and rat synaptosomes

The uptake of radioactive -aminobutyric acid (GABA) andd-aspartate and the effect of SKF 89976-A, a non-substrate inhibitor of the GABA transporter, on this uptake have been investigated. Neuronal cultures from eight-day-old chick embryos grown for three or six days in vitro, were used as a model. For comparison, we also used the P₂-fraction from rat. Neuronal cultures grown for three and six days expressed high-affinity uptake systems for [³H]GABA and ford-[³H]aspartate with an increasing V_max during this period. The lipophilic non-substrate GABA uptake inhibitor, SKF 89976-A, inhibited transporter mediated uptake of GABA both in cell cultures from chicken, and in P₂-fractions from rat. The results also showed that SKF 89976-A was a poor inhibitor of the uptake ofd-aspartate. We found no non-saturable uptake ofd-aspartate.     

Immunochemical and biological analysis of pheromone biosynthesis activating neuropeptide in Heliothis peltigera.

This study describes the preparation and characterization of a highly specific antiserum to Helicoverpa zea pheromone biosynthesis activating neuropeptide (Hez-PBAN), and the use of this antiserum, in an enzyme linked immunosorbent assay (ELISA), to determine: a) the content of endogenous PBAN in head extracts of male and female Heliothis peltigera; b) the level of PBAN at different developmental stages; and c) the content of PBAN in four different moth species. Cross-reactivity studies revealed that the antiserum is directed mainly toward the N-terminal region of the neuropeptide, and that it exhibits similar binding affinities toward the oxidized and reduced forms of PBAN. Analysis of PBAN content in head extracts of male and female H. peltigera, at scotophase, revealed the presence of 4.97 and 4.58 pmol, respectively, in 3-day-old moths, and 5.33 and 4.78 pmol, respectively, in 7-day-old moths. The similarity in the content of PBAN at both ages and sexes was in accordance with the amount of pheromonotropic activity in these extracts which stimulated pheromone biosynthesis to a similar level. Analysis of PBAN-like immunoreactivity (IR) in head extracts of H. peltigera larvae and pupae demonstrated the existence of the neuropeptide in the 4th larval instar and continued to increase as a function of development. No IR could be detected in the first three larval instars. The larval and pupal extracts also exerted pheromonotropic activity which followed a similar pattern. The activity in these extracts, however, was considerably lower than that found in adult male and female heads. IR was also detected in head extracts of three other Noctuidae moths: Helicoverpa armigera, Cornutiplusia circumflexa and Spodoptera littoralis, indicating a high degree of chemical and structural similarity of PBAN in these moths.     

Diel water movement between parenchyma and chlorenchyma of two desert CAM plants under dry and wet conditions

Abstract. Electric-circuit analogue models of the water relations of crassulacean acid metabolism (CAM) succulents such as Agave deserti and Ferocactus acanthodes have predicted diel movement of water between the water-storage parenchyma and the photo-synthetic chlorenchyma. Injection of tritiated water into either tissue in the laboratory confirmed substantial and bidirectional water movements, especially under conditions of wet soil. For A. deserti , water movement from the water-storage parenchyma to the chlorenchyma increased at night as the chlorenchyma osmotic pressure increased. Although nocturnal osmotic pressure increases and transpiration for both species were minimal in the field under dry conditions, diel changes in the deuterium: hydrogen ratio (expressed as ΔD) were similar for the water-storage parenchyma and the chlorenchyma. Such indication of [substantial mixing of water between the tissues over a 24-h cycle was more evident under wet conditions in the field. For A. deserti , ΔD then increased by 32%o from the afternoon to midnight and was essentially identical in the water-storage parenchyma and the chlorenchyma. For F. acanthodes , the diel changes in ΔD were one-third those of A. deserti , and ΔD was always slightly higher for the chlorenchyma than for the water-storage parenchyma, apparently reflecting the lower surface-to-volume ratio of A. deserti. In summary, data obtained using radioactive and stable isotopes strongly supported model predictions concerning diel cycles of internal water distribution for these CAM species.     

Effects of source-sink relations on photosynthetic acclimation to elevated CO2

Abstract. While photosynthesis of C₃ plants is stimulated by an increase in the atmospheric CO₂ concentration, photosynthetic capacity is often reduced after long-term exposure to elevated CO₂. This reduction appears to be brought about by end product inhibition, resulting from an imbalance in the supply and demand of carbohydrates. A review of the literature revealed that the reduction of photosynthetic capacity in elevated CO₂ was most pronounced when the increased supply of carbohydrates was combined with small sink size. The volume of pots in which plants were grown affected the sink size by restricting root growth. While plants grown in small pots had a reduced photosynthetic capacity, plants grown in the field showed no reduction or an increase in this capacity. Pot volume also determined the effect of elevated CO₂ on the root/shoot ratio: the root/shoot ratio increased when root growth was not restricted and decreased in plants grown in small pots. The data presented in this paper suggest that plants growing in the field will maintain a high photosynthetic capacity as the atmospheric CO₂ level continues to rise.