The metabolism of testosterone by human,rabbit and rat kidney

• 1.1. The metabolism of testosterone by the homogenate, microsomal and soluble fractions of human, rabbit and rat kidneys was investigated. Human kidneys were obtained from patients who underwent surgery for cancer, and the metabolism of testosterone was investigated using the intact part and in some cases also the cancerous part.
• 2.2. Testosterone was metabolized by the homogenate and microsomal preparation of male and female human and male rat kidneys to androstenedione (4-androstene-3,17-dione) and to a lesser extent to monohydroxymonoketosteroids, dihydroxysteroids and to more polar metabolites. The main metabolites in the soluble fraction were dihydroxysteroids of the 5β-series.
• 3.3. The rabbit kidneys differed from human and rat kidneys by showing a much greater rate of testosterone metabolism and by producing epitestosterone—via androstenedione—as a major metabolite. The formation of epitestosterone was especially marked in the homogenate of rabbit kidney.

     

Metabolism of testosterone in human lung in vitro

• 1.1. The metabolism of 4-¹⁴C-testosterone in human lung in vitro was investigated.
• 2.2. The metabolism was most pronounced in incubations of homogenated tissue, whereas it was rather restricted in the mitochondrial, microsomal and soluble fraction incubations.
• 3.3. The by far most prominent metabolite in all experiments was androst-4-ene-3,17-dione.
• 4.4. No slfate or glucuronide conjugation took place.

     

Fetal lung metabolism: Response to maternal fasting

• 1.1. Fetal lung metabolic response to maternal fasting late in gestation was investigated.
• 2.2. Maternal fasting 4 days before term was associated with low fetal plasma glucose and insulin levels but increased levels of fetal plasma glucagon, glycerol, lactate and fatty acids.
• 3.3. Fetuses from fasted mothers showed a significant decrease in body weight (30%), lung weight (30%) and lung glycogen (46%), but no change in lung protein, phospholipid or total lung DNA, suggesting that lung size is affected more than maturation.
• 4.4. Fetal lung slices incubated in vitro showed that lactate oxidation to CO₂ equalled that of glucose in control fetal lungs and was unaffected by maternal fasting, while glucose oxidation was depressed (23%).
• 5.5. Maternal fasting significantly decreased in vitro incorporation of [U-¹⁴C]-glucose, [U-¹⁴C]lactate and [1-¹⁴C]palmitate into lung phospholipids.
• 6.6. Fetal lungs from fasted mothers showed increased conversion of lactate to glucose, indicating gluconeogenic potential by fetal lung.
• 7.7. These studies show that plasma lactate serves as an important energy fuel and substrate for lipid synthesis for the fetal lung, and maternal fasting markedly alters fetal lung metabolism.

     

Interaction of oestrogen and of physiological progesterone metabolites in the control of gonadotropin secretion

The combined effect of oestrogen and progesterone on the release of LH has been evaluated in female rats castrated three weeks earlier. In addition to progesterone, its 5α-reduced metabolites (5α-pregnan-3,20-dione, DHP; 5α-pregnan-3α-ol-20-one, 3α-ol; 5α-pregnan-3β-ol-20-one, 3β-ol, that are known to be formed in the brain and in the anterior pituitary, have also been studied.Two different approaches have been used: (1) Ethinyl oestradiol (EE) has been implanted into the median eminence (ME) of the animals, and left in situ for 5 days; the different progestagens were injected subcutaneously in a dose of 100 μg/rat in the afternoon of the 5th post-implantation day. The animals were killed 16 h later. Half of the progestagen-injected animals received 10 ng of LH-RH i.v. 20 min before sacrifice;

1. 1.(2) EE has been placed directly into the anterior pituitary (AP) and again the implant has been followed by systemic treatment with the various progestagens. In these animals, the hypothalamic LH-RH content has been measured in addition to serum levels of LH. The results indicate that:
2. 2.(3) EE implants either in ME or in AP significantly depress serum LH;
3. 3.(4) In ME-EE-implanted animals, either P or DHP cause a large increase in serum LH, while neither 3α-ol nor 3β-ol are effective; on the contrary in the animals bearing AP implants no stimulatory effect was induced by progestagen administration;
4. 4.(5) The pituitary of ME-EE implanted animals is much more responsive to LH-RH than that of sham-implanted controls, as indicated by the increase in serum LH after LH-RH administration;
5. 5.(6) P and DHP significantly reduce LH-RH responses in ME-EE implanted animals; on the contrary 3α-ol and 3β-ol dramatically increase the pituitary responsiveness to the decapeptide in the same experimental conditions;
6. 6.(7) Castration significantly reduces LH-RH content in the hypothalamus; AP-implanted oestrogens either alone or in combination with P or DHP are unable to re-establish normal intrahypothalamic stores of LH-RH; on the other hand 3α-ol givel to AP-EE-implanted animals lowers hypothalamic content of the decapeptide, while increasing its serum levels.

     

Cloning and characterization of rabbit pancreatic colipase

• 1.1. Among the digestive enzymes synthesized by pancreas, lipase is the principle lipolytic enzyme which hydrolyses dietary glycerides.
• 2.2. For its action it requires a coenzyme, colipase.
• 3.3. The molecular mechanisms of the interaction of these two are not fully understood.
• 4.4. Further, molecular events that regulate and influence lipid absorption are ill denned.
• 5.5. The rabbit is the conventional animal model for the study of lipid absorption. We have undertaken the molecular cloning, and characterization of rabbit pancreatic colipase, the coenzyme for pancreatic lipase.
• 6.6. Colipase has been cloned from a gt 11 library of an adult rabbit pancreatic cDNA by probing with an oligonucleotide derived from human colipase sequence.
• 7.7. The total reading frame consists of 321 nucleotides coding for 90 amino acids of the functional protein and 17 nucleotides of the leader peptide.
• 8.8. Northern blot analysis revealed a distinct band around 0.5kb. Comparison with other species revealed an over all homology of 75% at the nucleotide level.
• 9.9. At the amino acid level highest conservation is observed at the lipase-binding region (AA 53–73).
• 10.10. Rabbit enzyme also retained the N-terminal pentapeptide of it preform.
• 11.11. The regions of homology and conservation may aid to define the sites of interaction of colipase with lipase.

     

Variability of histone H1 in rabbit populations

• 1.1. Perchloric acid-soluble proteins containing H1 histone as a main component were isolated from whole liver, lung and kidney of New Zealand White, Chinchilla, French Silver and Czech Spotted rabbits.
• 2.2. Proteins were resolved in a two-dimensional polyacrylamide slab gel into 4–5 spots depending on the tissue.
• 3.3. One of the histone subtypes, Hle, was found to be nonuniformly distributed within rabbit populations.
• 4.4. The prevailing fraction of animals had only a single spot of H1e (phenotype A). Approximately 10–28% of animals, depending on the breed, had two spots of H1e (e₁ and e₂; phenotype B) that slightly differed in the apparent molecular weights.
• 5.5. These two distinct gel patterns of H1e showed no tissue specificity, and the same phenotype was revealed in all tissues from the same animal.

     

Distribution of lysosomal hydrolases in glomerular and tubular fractions of rabbit kidney cortex

• 1.1. The results on the distribution of lysosomal hydrolases indicated that the specific activity of acid phosphatase is 5 times higher in glomeruli compared to tubular fraction. The activity of gb-galactosidase was 4 times higher m tubules compared to glomeruli.
• 2.2. Sephadex G-150 gel chromatography of soluble fraction of cortex homogenate, glomeruli and tubules indicated that the enzyme acid phosphatase occurs in multiple forms designated as peaks I, II and III.
• 3.3. The specific activity of peak II was 12–15 times higher in glomeruli compared to the cortex homogenate, and very low in tubules.
• 4.4. Arylsulphatases A and B were also 2–3 times higher in the glomerular fraction compared to the tubules.

     

Steroid synthesizing capacity of the dorsal body of Helix pomatia L. (Gastropoda)—an in vitro study

• 1.1. In vitro studies demonstrated the presence of the enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD) in the dorsal body complex, ovotestis and buccal ganglia of Helix pomatia.
• 2.2. Results of incubations with tritiated pregnenolone and tritiated dehydroepiandrosterone indicate substrate specificity of the 3β-hydroxysteroid dehydrogenase.
• 3.3. The activity of the two 3β-hydroxysteroid dehydrogenases vary independently of each other during different physiological states of the animal.
• 4.4. Before oviposition the conversion of dehydroepiandrosterone into androstenedione in all tissues investigated exceeds that of pregnenolone into progesterone. On the contrary, after oviposition this is reversed for the ovotestis.
• 5.5. The relative importance of the pathways in steroidogenesis followed in the organs studied is discussed.

     

NAD(P)H dehydrogenase from rabbit and rat liver: Purification and some properties

• 1.1. NAD(P)H dehydrogenase from rabbit liver was purified to electrophoretic homogeneity using a procedure also found applicable for the rat liver enzyme.
• 2.2. Rabbit and rat liver enzymes showed different behaviour in isoelectric focusing and different K_m values and turnover numbers.
• 3.3. Both enzymes were inhibited to similar extents by warfarin.
• 4.4. The rabbit enzyme is composed of two subunits of mol. wt 27,000 and contained 1 FAD group per subunit.
• 5.5. Some absorption and circular dichroism properties of the rat enzyme are shown.

     

Palmitic acid metabolism in hepatopancreas of the freshwater shrimp Macrobrachium borellii

• 1.1. The palmitic acid fate as substrate for the synthesis of either glycerides or other fatty acids was studied in vivo and in the microsomal fraction from hepatopancreas of Macrobrachium borellii.
• 2.2. Most of the palmitic acid administered in vivo circulated to the hepatopancreas, being incorporated mainly in the triacylglycerol (TG) fraction.
• 3.3. Palmitic acid transformations into palmitoleic, stearic and oleic acids were observed in the hepatopancreas.
• 4.4. The in vitro biosynthesis of TG in hepatopancreas was more active than in other tissues. In the microsomal fraction, palmitic acid was also incorporated mainly in TG, and followed the α-glycerophosphate pathway.

     

Evidence that the 5' end of rabbit globin mRNA is hybridized with its 3' end

• 1.1. A radiopolyadenylated rabbit globin mRNA was treated with different concentrations of ribonuclease V₁ from cobra venom.
• 2.2. The enzymatic digests were chromatographed on an aminophenylboronate-agarose column, which specifically captured the cap structure i.e. n⁷G(5') ppp (5') NmP.
• 3.3. When the capture fragment was chromatographed on a Sephadex G-100 column, its size was smaller than the native molecule and also bore radioactivity, i.e. a poly(A) tail.
• 4.4. These results provide evidence that the 5' end (which encompasses the cap structure) of rabbit globin mRNA is hybridized and in close proximity to its 3' end.
• 5.5. We conclude that this conformation is required for messenger translation efficiency.

     

Sterol composition of two actiniaria

• 1.1. The sterol composition of Condylactis aurantiaca and Cereus pedunculatus (phylum Coelenterata, class Anthozoa, order Actiniaria) was investigated by silver nitrate-silica gel column chromatography, combined gas chromatography-mass spectrometry and NMR.
• 2.2. Sea anemones contained Δ³-sterols accompanied by small amounts of Δ^5.7-sterols and ring saturated sterols.
• 3.3. Sterols with 27 carbon atoms are predominant and cholesterol is the principal sterol, followed by 24-methylenecholesterol.
• 4.4. A 4-methyl ring saturated sterol, identified as 4,24-dimethyl-5α-cholest-24(28)-en-3β-ol, occurs in small amount in Actiniaria, accompanied by the corresponding 4-demethylstanol.

     

Chemical structures of mono-, di-, tri- and tetraglycosyl glycerides in rice bran

• 1.1. Monoglycosyl monoglyceride, mono-, di-, tri- and tetraglycosyl diglycerides were isolated from rice bran and characterized for their chemical structures.
• 2.2. Monoglycosyl monoglycerides were characterized as Gal(β1' → 3)-1- or 2-monoacyl-sn-glycerol and Glc(β1' → 3)-1- or 2-monoacyl-sn-glycerol.
• 3.3. The structures ofmonoglycosyl diglyceride were Gal(β1' → 3)-1,2-diacyl-sn-glycerol and Glc(β1' → 3)-1,2-diacyl-sn-glycerol. Epimeric separation of the galactosyl and glucosyl glycerides was for the first time achieved by thin-layer chromatography.
• 4.4. The main diglycosyl diglyceride was shown to be Gal(α1' → 6')-Gal(β1' → 3)-1,2-diacyl-sn-glycerol.
• 5.5. The major structure of triglycosyl diglyceride was characterized as Gal(α1″' → 6″)-Gal(α1″ → 6')-Gal(β1' → 3)-1,2-diacyl-sn-glycerol.
• 6.6. The representative structure of tetraglycosyl diglyceride was for the first time established as Gal(α1″ → 6″')-Gal(α1″' α 6″)-Gal(α1″ → 6')-Gal(βl' → 3)-1, 2-diacyl-sn-glycerol.

     

Contrast in adenine uptake by chicken and rabbit erythrocytes in vitro

• 1.1. Relative to rabbit erythrocytes, chicken red blood cells exhibit a much greater capacity to utilize [³H]adenine for nucleotide synthesis in vitro, even at 5°C and in the absence of added inorganic phosphate.
• 2.2. This difference is largely due to a higher concentration of phosphoribosylpyrophosphate and greater activity of adenine phosphoribosyltransferase in the avian cells. lli]3. The capacity of avian erythrocytes for utilization of guanine and hypoxanthine is several fold less than that of adenine.
• 3.4. The data are consistent with lower activity for hypoxanthine/guanine phosphoribosyltransferase than for adenine phosphoribosyltransferase in intact chicken erythrocytes.
• 4.5. The results indicate that reutilization of adenine by chicken erythrocytes may be physiologically significant.

     

The intracellular compartmentation of metabolites in isolated kidney cortex tubules

• 1.1. A method is described to measure cytosolic and mitochondrial metabolites in isolated kidney tubule suspensions.
• 2.2. With the use of digitonin, 95% of cytosolic metabolites are released into the supernatant fraction whereas mitochondrial matrix enzymes are retained in the pellet fraction.
• 3.3. In a study of adaptation to acidosis, different α-oxoglutarate gradients between the tubular cell compartments are obtained, when medium pH is changed from 7.0 to 7.8.

     

Comparison of metabolic effects of EGF,TGF-α, and TGF-β1 in primary culture of fetal bovine myoblasts and rat L6 myoblasts

• 1.1. Comparative studies of EGF, TGF-α, and TGF-βl action on the synthesis of DNA and cellular proteins in rat L6 myogenic cells and fetal bovine myoblasts demonstrated considerable differences between particular growth factors, dependent on dose and target cells.
• 2.2. Among examined growth factors only EGF exerted mitostimulatory action, more pronounced at lower concentrations. EGF, progressively with dose, stimulated protein synthesis much more effectively in fetal bovine myoblasts than in L6 cells.
• 3.3. The dynamics of stimulation of protein synthesis by TGF-α was greater than by EGF in both examined types of cell cultures.
• 4.4. The maximal response of fetal bovine myoblasts to TGF-α in a concentration of 100 ng/ml reached 370%, whereas EGF in a 10 times higher concentration stimulated protein synthesis only to 123% of control.
• 5.5. In contrast to EGF, TGF-α significantly inhibits DNA synthesis. Inhibition of the mitogenic response with simultaneous stimulation of protein synthesis by TGF-α may indicate changes toward cell differentiation.
• 6.6. TGF-β 1 in smallest concentration inhibits both DNA and protein synthesis. The suppressive action of TGF-β 1 was more distinct in fetal bovine myoblasts than in the L6 cell line.
• 7.7. Increasing concentrations of TGF-β l diminished its inhibitory effect, even leading to stimulation of protein synthesis at higher doses in L6 myoblasts.

     

Metabolic and contractile differentiation of rabbit muscles during growth

• 1.1. A study was carried out of post-natal evolution of the oxidative, glycolytic and contractile capacities in various types of rabbit muscle.
• 2.2. At birth, muscles are non-differentiated and present very limited metabolic and contractile activity, metabolism is mainly oxidative in all muscles.
• 3.3. Although muscular discrimination is manifest from the sixth week after birth, the glycolytic metabolism reaches its maximum capacity only after six to eight weeks.
• 4.4. Subsequently, oxidative metabolic capacity steadily decreases until adulthood.

     

The influence of environmental and incubation temperature on fatty acid synthetase from flounder (Platichthys flesus L.) liver

• 1.1. Fatty acid synthetase from liver of cold and warm adapted flounder and rabbit was purified to homogenity and compared.
• 2.2. The mol. wt of the cold and warm flounder enzyme was estimated to be about 457,000.
• 3.3. The kinetic properties were found to be similar for warm and cold adapted flounder liver enzyme and not different from the rabbit liver enzyme when measured at 5, 10, 15, 20 and 37°C.
• 4.4. Palmitic acid was the main product of both the flounder and rabbit enzyme, but significant amounts of butyric acid were also synthesized. The product composition did not change for any of the enzymes tested when the incubation temperature was changed.
• 5.5. It was concluded that fatty acid synthetase from flounder liver is similar to mammalian fatty acid synthetase with regard to molecular weight and kinetic properties.

     

Steroid metabolites of the far eastern Holothurian Stichopus japonicus Selenka

• 1.1. Sulphated and etherified sterols were isolated from the far eastern holothurian Stichopus japonicus S. The sterol composition of both fractions was determined using gas-liquid chromatography and mass-spectroscopic methods. The structures of individual sterols were proved on the basis of mass-spectrometry and ¹H-NMR-spectroscopy data.
• 2.2. The structures of 29 sterols were established.
• 3.3. Sterols (22E, 24R)-23,24-dimethyl-5α-cholest-22-en-3β-ol, 23,24-dimethyl-cholesta-5,22-dien-3β-ol, 24-methyl-cholesta-5,24(28)-dien-3β-ol, (24Z)-24-ethyl-cholesta-5,24(28)-dien-3β-ol, 24-nor-cholesta-5,22-dien-3β-ol, 24-ethyl-cholesta-5,25-dien-3β-ol were described for holothurians for the first time.
• 4.4. Δ⁵-sterols were shown to be the main components of the sulphated alcohol fractions (67.61%), while the saturated and Δ⁷-sterols were there in less quantities (14.72 and 9.52%, respectively).
• 5.5. The etherified sterols were represented, mainly, by saturated and Δ⁷-sterols (37.82% and 33.95%, respectively). Δ⁵-sterols were 19%.
• 6.6. The sensitivity of liposomal membranes, containing steroid metabolites of the holothurian St. japonicus (Δ⁷-, sulphated and glycosilated sterols) to the action of endotoxin-stichoposide A, was studied.

     

Phosphorylation in crayfish (Procambarus clarkii) eggs during hatching

• 1.1.|The high-energy phosphorylation metabolism in crayfish, Procambarus clarkii eggs during brooding and juvenile crayfish after hatching was studied by in vivo³¹P nuclear magnetic resonance (³¹P NMR) spectroscopy.
• 2.2.|Inorganic phosphoric acid (Pi) and adenosine-5′-triphosphate ATP(γ-,α-,β-) were detected in the dark brownish red eggs after oviposition.
• 3.3.|In orange unhatched eggs, only sugar phosphate (SP), Pi and resolved phosphometabolite from ATP were observed.
• 4.4.|Peaks of SP, Pi, arginine phosphate (Arg-P), and ATP (γ,α,β) appeared in larvae of crayfish after hatching (nauplius, zoea and juvenile crayfish).
• 5.5.|The high-energy phosphorylation metabolism changed to an anaerobic condition along with a decrease in the concentration of dissolved oxygen in fresh water.