An in vitro study of short-chain fatty acid concentrations,production and absorption in pig (Sus scrofa) colon

• 1.1. Short-chain fatty acid concentration was 180mmol/l in the proximal colon and decreased to 108 mmol/l in the rectum.
• 2.2. Fermentation in chymus from different regions of the colon, showed the pattern of end products to reflect the substrate and not the site of the colon.
• 3.3. Isolated mucosa from proximal and distal colon had electroneutral sodium absorption of 4.8 ± 0.2 and 2.9 ± 0.8 μeq/cm² hr in bicarbonate free media, which was abolished in the absence of chloride.
• 4.4. Electroneutral sodium absorption was enhanced by short-chain fatty acids in the proximal colon and could be described by Michaelis-Menten kinetics with K_m 2.0–11 mmol/l and J_m 1.6–3.6μeq/cm² hr. In the distal colon the stimulation was smaller and propionate even inhibited sodium absorption.
• 5.5. Butyrate was absorbed in the proximal colon, whereas acetate and propionate, and butyrate in the distal colon had a flux ratio of one.
• 6.6. Amiloride (5 mmol/l) inhibited sodium absorption and net butyrate absorption.

     

In vitro substrate utilization for lipid synthesis in liver explants from hyperthyroid chickens

• 1.1. Indian River male broiler chickens growing from 7 to 28 days of age were fed diets containing 12, 18, 24 and 30% protein + 0 or 1 mg triiodothyronine (T₃)/kg of diet to study energetic costs of lipogenesis and the use of various substrates for in vitro lipogenesis.
• 2.2. De novo lipid and CO₂ production were determined in the presence of [1-¹⁴C]pyruvate, [2-¹⁴q]pyruvate, [3-¹⁴C]pyruvate, [2-¹⁴C]acetate and [U-¹⁴C]alanine.
• 3.3. Oxygen consumption was determined in mitochondrial preparations to estimate the energetic costs in expiants synthesizing lipid.
• 4.4. Radiolabeled CO₂ derived from [1-¹⁴C]pyruvate was used as an estimate of coenzyme A availability in liver expiants. Lipids derived from [2-¹⁴C]pyruvate, [2-¹⁴C]acetate and [U-¹⁴C]alanine estimate relative substrate efficiency.
• 5.5. Labeled CO₂ production from [1-¹⁴C]pyruvate was greatest in that group fed a 12% protein diet and least in the group fed a 30% protein diet.
• 6.6. In addition, T₃ increased CO₂ production from [1-¹⁴C]pyruvate.
• 7.7. The production of ¹⁴CO₂ from the second carbon of pyruvate or acetate was increased by T₃.
• 8.8. The low-protein diet (12% protein) increased (P <0.05) lipogenesis.
• 9.9. Adding T₃ to the diets decreased carbon flux into lipid from all substrates, but increased CO₂ production from all substrates without changing stage 3 and 4 respiration rates in mitochondrial preparations.
• 10.10. These observations imply that coenzyme A availability may have regulated de novo lipogenesis in the present study.
• 11.11. It was also concluded that previously noted effects of T₃ on intermediary metabolism may involve metabolic pathways that do not involve changes in mitochondrial function.

     

Effects of inhibition of nadph: cytochrome p-450 reductase on benzo(a)pyrene metabolism in mouse liver microsomes

• 1.1. Effects of antioxidants (butylated hydroxytoluene and nor-dihydroguaiaretic acid), vitamin K-related quinones (vitamin K₁ and coenzyme Q₁₀) and inorganic copper (CuSO₄), in concentrations inhibiting NADPH: cytochrome P -450 reductase, were re-examined on benzo(a)pyrene metabolism in mouse liver uninduced microsomes.
• 2.2. It was found that all these compounds decrease production of the two-electron oxygenation products of benzo(a)pyrene (monophenoles, diols) and the amounts of glucuronides in a manner parallel to their inhibitory potency against NADPH: cytochrome P-450 reductase.
• 3.3. No correlation was found between amounts of one-electron oxidation products of benzo(a)pyrene and inhibition of NADPH: cytochrome P-450 reductase.
• 4.4. Without added UDPGA the compounds studied decreased protein associated benzo(a)pyrene metabolites in parallel to the decreased overall metabolism of this polyaromatic hydrocarbon.
• 5.5. The mode of action of the studied compounds is discussed.

     

LDH isozymes in amazon fish—III. Distribution patterns and functional properties in Serrasalmidae (Teleostei: Ostariophysi)

• 1.1. The patterns of distribution of LDH isozymes in five tissues from 12 Serrasalmidae species have been studied through two-fold serial dilution (Klebe's test) as well as the pyruvate inhibition of LDH enzyme in skeletal and heart muscles (low/high ratios).
• 2.2. The species' electrophoretic patterns differ by orthologous A₄ isozyme mobilities since the orthologous B₄ isozymes present similar electrophoretic migration. These differences between Ldh-A and Ldh-B products reflect three-, four-, and five-banded patterns. Thus, different LDH isozyme numbers formed from A and B subunits should not be used as an evolutionary or phylogenetic characteristic from different taxonomic groups.
• 3.3. Out of 66 pairs of species only five pairs showed significant differences in the distribution patterns in all five analyzed tissues, while no pair of species showed the same distribution in these tissues. This variation was explained as differential regulation of structural genes among tissues and/or species.
• 4.4. Functional properties showed significant between the LDHs from heart and skeletal muscles, and are consistent with a preference for aerobic metabolism. We suppose that by selecting B-like subunits these fishes are able to maintain good control of aerobic/anaerobic transitions, maintaining predominantly oxidative metabolism even in hypoxic waters, with which they have to cope.

     

Cholesterol metabolism in new world primates: Comparative studies in two tamarin species (Saguinus oedipus and Saguinus fuscicollis) and the squirrel monkey (Saimiri sciureus)

• 1.1. Cholesterol metabolism has been characterized in three species of New World primates, the cotton-top tamarin, the saddle-back tamarin, and the squirrel monkey.
• 2.2. When fed a diet containing cholesterol, the three species exhibited differing responses of plasma cholesterol levels.
• 3.3. Dietary cholesterol absorption was determined and plasma cholesterol die-away kinetics were analyzed in terms of a two-pool model.
• 4.4. The results of the analyses of cholesterol turnover are consistent with the observed species-specific differences in plasma cholesterol values and cholesterol absorption.
• 5.5. Cholesterol metabolism differs between the two tamarin species, as well as between the tamarins and the squirrel monkey.
• 6.6. Implications of species-specific differences between tamarin species are discussed in terms of the use of tamarin species as animal models for comparative studies of cholesterol metabolism and the etiology of cancer and cardiovascular disease.

     

Possible origin of extremely high contents of vitamin D3 in some kinds of fish liver

• 1.1. Comparative studies on the possible origin of extremely high contents of vitamin D₃ in some kinds of fish liver were performed.
• 2.2. Neither photochemical formation of vitamin D₃ in fish skin by solar radiation of 7-dehydrocholesterol (7-DHC) nor nonphotochemical enzymatic formation of vitamin D₃ from 7-DHC in fish liver was demonstrated as the origin of vitamin D₃.
• 3.3. On the other hand, when bastard halibuts and carps were farmed from fingerlings to adults with feedstuff's containing vitamin D₂ or D₃, significant amounts of the vitamins were accumulated in the fish liver.
• 4.4. The contents of vitamins D₂ and D₃ in bastard halibut liver increased according to the duration of farming and dose responses of the vitamins in carp liver were observed.
• 5.5. Significant amounts of vitamins D₂ and D₃ in phytoplankton and vitamin D₃ in Zooplankton and small fish were detected.
• 6.6. Therefore, we have concluded that the most probable origin of vitamin D₃ in fish liver is a result of food chains from plankton.

     

Dietary supplementation of vitamin E fails to prevent the development of hyperoxic lung injury in the premature guinea pig

• 1.1. The benefit of dietary vitamin E supplementation in preventing oxidative-induced lung injury was investigated. Three day preterm guinea pig pups were exposed to hyperoxic (85% O₂) or normoxic (21% O₂) conditions. The animals were fed either a standard low birthweight human infant formula milk (6.4 mg/l vitamin E), or a vitamin E supplemented milk (100 mg/l) for up to 7 days.
• 2.2. After 3 days vitamin E supplementation, plasma but not erythrocyte vitamin E concentrations were elevated, while following 7 days both plasma and erythrocyte vitamin E concentrations were significantly increased.
• 3.3. Lung and liver vitamin E concentrations were elevated at both 3 and 7 days. At 3 days the increase in lung vitamin E was oxygen-dependent, suggesting that the lung increases uptake of vitamin E in response to oxidative stress.
• 4.4. Despite an increase in the vitamin E concentration of the lungs of preterm guinea pigs, no amelioration of the lung injury was observed. These results suggest that although vitamin E is a potent antioxidant, it is unable to protect adequately the lungs from reactive oxygen species in the absence of sufficient primary enzymatic antioxidant defences.

     

Comparative vitellin pattern and cladogenesis in Bacillus (insecta: Phasmatodea)

• 1.1. Under denaturing conditions (SDS-PAGE) the two natural vitellins of Bacillus taxa released five different polypeptides (A₁, A₂, A₃, B₁, B₂).
• 2.2. A₂ and B₂ bands from the two bisexual species (B. rossius and B. grandii) were found to differ; furthermore a non-vitellin yolk protein characterizes the subsepecies B.g. benazzii.
• 3.3. From gels and their densitometric scanning profiles it is clear that parental polypeptides are expressed in the thelytokous parthenogenetic hybrids (B. whitei, B. lynceorum) and in the hybridogenetic B. rossius-grandii benazzii.
• 4.4. A comparative approach of vitellin patterns appears fully adequate for tracing phylogenetic relationships and recognizing cladogenetic events.

     

Effect of 13-hydroperoxy-9,11-octadecadienoic acid (13-hpode) on arachidonic acid metabolism in rabbit platelets

• 1.1. The effect of 13-hydroperoxy-9,11-octadecadienoic acid (13-HPODE) on the formation of thromboxane (TX) B₂, 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) from exogenous arachidonic acid in washed rabbit platelets was examined.
• 2.2. 13-HPODE inhibited TXB₂ and HHT formation without affecting 12-HETE production.
• 3.3. 13-Hydroxy-9,11-octadecadienoic acid which was produced rapidly from 13-HPODE, did not suppress the formation of TXB₂ and HHT, indicating the requirement of the hydroperoxy moiety for the inhibitory effect of 13-HPODE on TXB₂ and HHT formation.
• 4.4. Experiments utilizing mannitol and dimethyl sulfoxide (hydroxy radical scavengers) revealed that the action of 13-HPODE is not due to hydroxy radicals which are expected to be formed from 13-HPODE.
• 5.5. These results suggest that 13-HPODE is a selective inhibitor of platelet cyclo-oxygenase and may have functional effects within platelets.

     

Biomines-stimulated phosphorylation and (Na+, K+-ATPase in the gills of the chinese crab,Eriocheir sinensis

• 1.1. Subcellular distribution of (NA⁺, K⁺-ATPase and ouabain-insensitive ATPase (Mg²⁺-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
• 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
• 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
• 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.

• 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
• 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P₃ from the posterior gills.
• 3.(c) No activation occurs with the fractions P₃ as well as P₁ or P₂ (not shown) from anterior gills of fresh water crab.
• 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
• 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
• 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.

     

Phosphoinositides and inositol phosphates in Discopyge tschudii electrocyte membranes

• 1.1. The metabolism of inositol (Ins)-containing phospholipids and inositol phosphates has been studied by following the incorporation and distribution of myo-[³ H]Ins in metabolically active electrocytes from the electric ray Discopyge tschudii.
• 2.2. The apparent initial rate of myo-[³H]Ins incorporation into total phosphoinositides was ca 8.2 fmol/mg protein/hr. Phosphatidylinositol (Ptdlns) displayed the highest levels of labelling. Lithium inhibited this incorporation probably by limiting the recycling of myo-[³H]Ins from [³H]Ins-monophosphate.
• 3.3. The formation of water-soluble products of phosphoinositides between 7 and 24 hr was 4.1 ± 0.2, 0.4 ± 0.2 and 3.0 ± 1.0 fmol/μmmol total lipid phosphorus for myo-[³H]InsP, -InsP₂ and Ins-P₃ respectively.
• 4.4. Lithium ions are shown to modulate phosphoinositide synthesis and Ins-phosphate accumulation. Ins-mono-, bis- and tris-phosphate production was enhanced 5-, 3- and 2-fold by Li +.
• 5.5. The above results suggest the participation of a C-type phospholipase and of Li-sensitive phosphatases in the modulation of phosphoinositide metabolism in the electrocyte.

     

Evidence for extracellular deamination of adenosine in the rat heart

• 1.1. In rat heart perfused with adenosine (10⁻⁶M), dilazep (10⁻⁴M) inhibited incorporation of adenosine into nucleotides (an index of nucleoside transport and phosphorylation) to a greater extent (70%) than metabolism to inosine and uric acid (40%) and actually increased the recovery of inosine to 30% of the adenosine infused.
• 2.2. Extrapolating for complete inhibition of transport suggested that 60% of adenosine metabolism was intracellular and 40% extracellular.
• 3.3. Static incubations of atria also gave an estimate for extracellular metabolism of 40%.
• 4.4. Adenosine deaminase was localised by immunocytochemistry to the extracellular surface of endothelial cells of small coronary arteries.
• 5.5. Extracellular deamination may explain the lack of effect of nucleoside transport inhibitors on responses to adenosine in rat heart.

     

Ionic dependence and vanadate sensitivity of (Na+, K+)-ATPase isolated from branchial sac of ascidians

• 1.1. Ion dependence and vanadium-induced inhibition on branchial sac ATPase in five species of ascidian Phlebobranchiata (vanadium-accumulating) and Stolidobranchiata (iron-accumulating) were studied.
• 2.2. The ATPase was obtained from the microsomal fraction, which was prepared from each ascidian branchial sac.
• 3.3. The ATPase was dependent on Mg²⁺ and activated by exogenous Na⁺ + K⁺.
• 4.4. Ouabain inhibited the ATPase activity in vitro, 10 μM to 100 μM vanadate, in vitro, suppressed the (Na⁺, K⁺)-ATPase.

     

Regulation of rat-kidney cortex fructose-1,6-bisphosphatase activity. II. Effects of adenine nucleotides

• 1.1. The native rat-kidney cortex Fructose-1,6-bisphosphatase is differentially regulated by adenine nucleotides in the presence of divalent cations.
• 2.2. Binding of AMP and ADP to the enzyme is co-operative. The inhibition by both nucleotides show an uncompetitive mechanism AMP being the most efficient inhibitor.
• 3.3. Mg²⁺ decreases the inhibition produced by AMP and ADP by enhancing their I_0.5 and completely annulates the inhibitory effect of ATP.
• 4.4. In the presence of Mn²⁺ ADP behaves as an inhibitor but no inhibition is evident with AMP, suggesting the existence of different allosteric sites for each nucleotide.

     

Sheep haemoglobin i or β b13(a10)gly → ser: an example of a cpg mutation in vertebrates. Characterization using fab-mass spectrometry and amino acid sequencing

• 1.1. The amino acid substitution which characterizes the haemoglobin I variant from sheep has been ascertained using a combination of Fast Atom Bombardment mass spectrometry and protein sequencing.
• 2.2. A Ser for Gly substitution at position 13 (10 of the A helix) was found in a polypeptide with the overall sequence of the β^B globin.
• 3.3. On the basis of the nucleotide sequence of the β^B-globin gene, a C to T transition occurring on a CpG doublet is considered to be responsible for the amino acid substitution.
• 4.4. This represents the first observation of a variant sheep Hb due to a mutation which is rather common in the human genome.
• 5.5. Amongst ruminants, serine is normally present at position 13 of goat and sheep ε¹¹ and γ chains and of bovine γ chain which had an independent and more ancient evolutionary origin than the β chains.

     

Catalytic and inhibitory properties of a major molecular form of acetylcholinesterase isolated from Lygus hesperus knight (Hemiptera: Miridae)

• 1.1. The major form of acetylcholinesterase (AChE) from Lygus hesperus demonstrated a greater affinity to selected substrates than unresolved AChE.
• 2.2. The turnover numbers of the native AChE were 7000 min⁻¹ for acetylthiocoline, 4800 for acetyl-(β-methyl) thiocholine, 3000 for propionylthiocholine, and 390 for S-butyrylthiocholine.
• 3.3. Each molecule of the major form had two active sites and each subunit had one active site.
• 4.4. Paraoxon or dichlorvos had a higher affinity to the major AChE form than to the unresolved AChE, resulting in a higher potency for the inhibition.
• 5.5. Some references of comparison are also made with AChE from other animal species.

     

Apparent low free magnesium levels in blue crab vas deferens determined by 31P NMR

• 1.1. ³¹P NMR examination of blue crab vas deferens reveals an α-β ATP chemical shift differences on average of 9.8 ppm.
• 2.2. This implies a free magnesium concentration well below 100 μM.
• 3.3. Thus crab vas deferens represents a new model for a low free magnesium system.
• 4.4. These results also point to a feature of carcine metabolism not previously recognized.

     

Purification and some properties of an atypical alkaline p-nitrophenylphosphate phosphatase activity from Halobacterium halobium

• 1.1. An alkaline p-nitrophenylphosphate phosphatase has been purified 440-fold from extracts of Hatobacterium halobium.
• 2.2. The enzyme has an apparent molecular weight of 24,000.
• 3.3. A K_m value for p-nitrophenylphosphate of 1.12mM has been found under optimal conditions.
• 4.4. The enzyme is selectively activated and stabilized by Mn²⁺.
• 5.5. It requires high salt concentrations for stability and maximum activity.
• 6.6. It displays an unusual restricted substrate specificity of 25 phosphate esters tested, only phosphotyrosine and casein were hydrolysed besides p-nitrophenylphosphate.

     

Some properties of ATPase activity in the intact cells of yeast Saccharomycopsis fibuligera

• 1.1. The properties of ATPase activity were studied with the cells at the early stationary phase of Saccharomycopsis fibuligera.
• 2.2. Optimal pH for the activity was approximately 7.
• 3.3. The activity was stimulated by Mg²⁺.
• 4.4. The activity was inhibited by NaF, DCCD, oligomycin, NaN₃, NaVO₃, or PCMB but not inhibited by ouabain.

     

Demonstration of highly specific and sensitive antibodies to a naturally occurring tetrahydroisoquinoline alkaloid,salsolidine

• 1.1. We report for the first time on the production and characterization of antibodies against a naturally occurring tetrahydroisoquinoline, namely salsolidine (6,7-dimethoxy-1-methyl-1,2,3,4-tetrahydroisoquinoline).
• 2.2. Immunogen synthesis was carried out by coupling the hapten salsolidine to bovine serum albumin (BSA) as carrier protein on the basis of reductive amination.
• 3.3. By immunization of rabbits with salsolidine-BSA conjugate antisalsolidine antibodies were produced.
• 4.4. At a final dilution of 1:1700 the highest-litre antiserum bound 35% of 0.21 pmol [³H] salsolidine. This antiserum was used to develop a radioimmunoassay for salsolidine.
• 5.5. Cross-reactivity studies revealed a high specificity of the antiserum to the hapten.
• 6.6. The antibodies had a high affinity to salsolidine (K_a = 1.5 × 10⁹ M⁻¹).
• 7.7. Standard curves covered a measuring range of 0.5–70 pmol/tube and the detection limit was found to be 0.27 pmol/tube.