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  • 1
    Electronic Resource
    Electronic Resource
    Dietary thiamin supply during lactation influences thiamin status in lactating rats and their offspring and the thiamin level in milk (1997)
    Springer
    European journal of nutrition 36 (1997), S. 169-175 
    Details
    ISSN: 1436-6215
    Keywords: Dietary thiamin supply ; lactation ; thiamin status ; milk ; rat ; Thiaminversorgung ; Laktation ; Thiaminstatus ; Milch ; Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Ziel der vorliegenden Studie war es, die Wirkung variierender Thiaminzulagen (Mangel bis Überschuß) in der Diät auf den Thiaminstatus laktierender Ratten und deren Nachkommen sowie auf den Thiaminspiegel der Milch zu untersuchen. Dazu wurden Ratten nach dem Werfen in 8 Gruppen (à 10 Tiere) eingeteilt, die während der Laktation über einen Zeitraum von 13 Tagen eine Diät mit 0, 2, 4, 6, 7, 40, 350 und 3 500 mg Thiamin/kg erhielten. Milch für die Bestimmung der Thiaminkonzentration wurde am 6. und 13. Laktationstag gewonnen. Am 14. Laktationstag wurden von allen Muttertieren und Würfen zur Ermittlung des Thiaminstatus die Aktivität der Transketolase in Blut, Leber und Gehirn sowie die Thiaminkonzentrationen im Körper gemessen. Die variierenden Thiaminzulagen beeinflußten innerhalb von 13 Tagen sowohl den Thiaminstatus der laktierenden Ratten als auch den der Nachkommen. Thiamin-frei ernährte Ratten zeigten Thiaminmangelsymptome auf der Basis von Wachstumsminderung und erniedrigten Transketolaseaktivitäten in Blut, Leber und Gehirn. Dabei reagierte die Transketolase im Blut sensibler auf eine Thiaminunterversorgung als in Geweben und erreichte ein Plateau bei einer Zufuhr von 6 mg/kg Thiamin. Die Thiaminkonzentration in der Milch lag in einem Bereich zwischen 0,1 und 19 mg/kg. Verglichen mit anderen Geweben reagierte die Milch beider Laktationsabschnitte am stärksten auf eine Thiaminunter- bzw. -überversorgung. Darüber hinaus konnte eine fehlende oder suboptimale Thiaminversorgung nicht durch einen verstärkten Übertritt von Thiaminreserven aus dem Körper in die Milch kompensiert werden. Auch die Thiaminspiegel in den Geweben und im Restkörper erhöhten sich mit steigender Thiaminzufuhr, wobei sich die Dosisabhängigkeit, die jedoch kein eindeutiges Sättigungsverhalten zeigte, in Blut und Leber stärker widerspiegelte als im Restkörper.
    Notes: Summary This study was conducted to examine the effect of dietary thiamin, ranging from deficient to excessive supplies, on thiamin status of lactating rats and their offspring, and the thiamin level in milk. Therefore, after parturition, rat dams were divided into eight groups of 10 each, and were fed diets with 0, 2, 4, 6, 7, 40, 350 and 3 500 mg/kg thiamin over a total of 13 days during lactation. Milk for determining the thiamin concentration was obtained from day 6 and 13 of lactation. At day 14 of lactation rat dams and their offspring were used to ascertain the thiamin status including transketolase activity of blood, liver and brain, and thiamin concentration in body. Thiamin supplies ranging from deficient to excessive dietary concentrations influenced both the thiamin levels of the lactating dams and their offspring within 13 days. Lactating rat dams fed a thiamin-free diet and their offspring were classified as thiamin-deficient on the basis of growth retardation and a lower activity of transketolase in blood, liver and brain. Within these variables transketolase in blood has been shown to be most sensitive, and reached a plateau feeding 6 mg/kg thiamin. The concentration of thiamin in milk ranged between 0.1 and 19 mg/kg. The findings also show that dietary thiamin had the strongest effect on thiamin in milk obtained from day 6 and 13 of lactation, and a deficient or suboptimal supply with thiamin was therefore not compensated for an intensified transfer of reserved body thiamin into milk. Also thiamin levels in tissues and carcass, which did not show any clear-cut saturation characteristic, increased with increasing dietary thiamin, and this dose-dependence was more marked in blood and liver than in carcass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01611396
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  • 2
    Electronic Resource
    Electronic Resource
    Benefit of more but smaller meals at a fixed daily protein intake (1997)
    Springer
    European journal of nutrition 36 (1997), S. 347-349 
    Details
    ISSN: 1436-6215
    Keywords: Meal frequency ; utilization ; rat ; 14C labeled amino acids ; leucine ; Fütterungshäufigkeit ; Verwertung ; Ratte ; 14C-markierte Aminosäuren ; Leucin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Der Einfluß der Häufigkeit der Nahrungsaufnahme auf die Entwicklung des Körpergewichts und auf den Proteinstatus, gemessen auf dem Niveau der Aminosäurenoxidation (Decarboxylierung) in der postabsorptiven Phase, wurde bei einer festen täglichen Proteinaufnahme untersucht. Wachsende Ratten (250g) wurden über eine Sonde mit einer Flüssignahrung versorgt, die auf dem Nutrison Standard basiert (1,6g Protein/d, 266 kJ ME/d). Diese Menge wurde entweder in Form von 2 großen Mahlzeiten am Beginn und am Ende, 6 kleineren Mahlzeiten oder als kontinuierliche Infusion über die gesamte Dunkelperiode (10h) gegeben. Nach 3 Wochen der Fütterung war die mittlere Wachstumsrate der Ratten, die kontinuierlich gefüttert wurden, 20% höher als die Tiere, die die gleiche Menge in 2 Mahlzeiten erhielten. Die Ratten, die 6 Mahlzeiten am Tag bekamen, hatten ein Wachstum, das ziemlich den Ratten entsprach, die kontinuierlich gefüttert wurden. Die prozentuale Wiederfindung der Markierung als14CO2 in der Atemluft nach Injektion (i. p.) von [1-14C]Leucin (4 h nach der letzten Mahlzeit) war signifikant höher (p,05) für die kontinuierlich gefütterten Tiere (27% SD 2,6) verglichen mit den Ratten, die zwei Mahlzeiten erhielten (21,9% SD 4,0). Der Wert für die Gruppe mit 6 Mahlzeiten lag dazwischen (24,5 SD 1,8). Die Resultate weisen darauf hin, daß die metabolische Verwertung von einer festen täglichen Proteinmenge durch den Weg der Zuführung deutlich beeinflußt wird. Hinsichtlich der Entwicklung des Körpergewichts und des Proteinstatus haben die Tiere mehr Nutzen von der gleichen Proteinmenge, wenn die Zuführung ausgeglichener erfolgt. Es wird vorgeschlagen, daß die Differenz durch die metabolische Restriktion für eine adäquate Verwertung von großen Mahlzeiten verursacht wird. Es wird deshalb angenommen, daß große Mahlzeiten zu einer Verschwendung von Aminosäuren in der postprandialen Phase führen. Eine Folge davon ist, daß weniger Aminosäuren im Körper gespeichert werden und in der postabsorptiven Phase verfügbar sind.
    Notes: Summary The influence of meal frequency on change of body weight and protein status, measured by level of amino acid oxidation (decarboxylation) in the postabsorptive state, was studied at a fixed daily protein intake. Growing rats (250g) were fed through gastric canula a feeding solution based on Nutrison Standard supplying 1.6g protein and 266kJ ME daily. This amount was given in either 2 large meals at the beginning and the end, or in 6 smaller meals, or by continuous infusion during entire dark period (10 hrs). After 3 weeks of feeding the mean growth rate of the rats fed continuously was nearly 20% higher than rats fed the same amount in 2 meals. The rats fed 6 meals a day had a growth rate rather similar to the rats fed continuously. The percentile recovery of label as14CO2 in the breath after an intraperitoneal injection of [1-14C]leucine (4 hrs after last meal) was significantly higher (p.05) for the animals fed continuously (27% sd 2.6) compared to the rats fed 2 meals (21.9% sd 4.0). The value for 6 meal group was intermediate (24.5 sd 1.8). The results indicate that the metabolic utilization of a fixed daily amount of protein is clearly influenced by the way of supply. With respect to the change of body weight and protein status, animals have more benefit of the same amount of protein if the supply is more equable. It is suggested that the difference is caused by metabolic restriction for an adequate utilisation of large meals. Therefore large meals are supposed to cause a waste of amino acids in the postprandial phase. As a consequence amino acid amount that will be stored in the body to be available in the postabsorptive phase will be less.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01617820
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  • 3
    Electronic Resource
    Electronic Resource
    Untersuchungen zum Einfluß einer unterschiedlichen Riboflavinversorgung während der Laktation auf den Riboflavingehalt von Milch, Leber und Restkörper laktierender Ratten (1997)
    Springer
    European journal of nutrition 36 (1997), S. 176-181 
    Details
    ISSN: 1436-6215
    Keywords: Riboflavin ; Milch ; Leber ; Restkörper ; Laktation ; Ratte ; Riboflavin ; milk ; liver ; carcass ; lactation ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The present study investigated the effect of various dietary riboflavin supplementations (0 to 4 000 mg/kg) during lactation on riboflavin concentrations of liver, carcass (bled body without intestine and liver), and milk in the rat. The experiment was conducted until the 14th day of lactation; milk samples were drawn on the 7th and 13th day of lactation. Riboflavin concentrations of milk raised continuously with increasing riboflavin supplementation; in the range between 0 and 10 mg/kg riboflavin supplementation, there was a linear relationship, and in the range between 12 and 4 000 mg/kg there was a logarithmic relationship between riboflavin supplementation and riboflavin concentration in the milk. Maximum riboflavin concentration of milk obtained by supplementation with 4 000 mg/kg was twelve-fold higher than without riboflavin supplementation. For riboflavin supplementation up to 12 mg/kg, riboflavin concentrations in milk on the 7th day of lactation and that on the 13th day of lactation were not different. In contrast, in rats fed diets with higher riboflavin supplementation, riboflavin concentrations were higher by 25 % in average in milk on the 13th day of lactation than in milk on the 7th day of lactation. Contrary to the milk, riboflavin concentrations in liver and carcass exhibited a saturation, which was achieved at a supplementation of 6 mg/kg (liver) and 10 mg/kg (carcass), respectively. Maximum riboflavin concentrations obtained at a supplementation of 4 000 mg/kg were 1.9- and 2.3-fold higher for liver and carcass, respectively, than concentrations obtained without riboflavin supplementation. The dose-response relationship using riboflavin concentrations of liver and carcass as response factors indicates a riboflavin requirement of 8 to 9 mg/kg for lactating rats fed a semisynthetic diet with 17.4 MJ ME/kg dry matter and 20.8 % protein in dry matter.
    Notes: Zusammenfassung In der vorliegenden Arbeit wurde der Einfluß unterschiedlicher Riboflavinzulagen zum Futter (0 bis 4 000 mg/kg) während der Laktation auf die Riboflavinkonzentrationen in Leber, Restkörper (ausgebluteter Gesamtkörper ohne Magen-Darm-Trakt und Leber) und Milch von Ratten untersucht. Der Versuch dauerte bis zum 14. Laktationstag; Milchproben wurden am 7. und am 13. Laktationstag gewonnen. Die Riboflavinkonzentration der Milch erhöhte sich mit steigender Zulage stetig, wobei im Bereich zwischen 0 und 10 mg Riboflavinzulage/kg Futter eine lineare und im Bereich zwischen 12 und 4 000 mg/kg eine logarithmische Funktion vorlag. Die maximale Riboflavinkonzentration in der Milch bei einer Zulage von 4 000 mg/kg war dabei etwa zwölfmal so hoch wie bei fehlender Zulage. Bei Riboflavinzulagen bis 12 mg/kg unterschieden sich die Riboflavinkonzentrationen der Milch am 7. und 13. Laktationstag nicht. Bei den höheren Zulagen waren die Konzentrationen der Milch am 13. Laktationstag im Mittel um 25 % höher als am 7. Laktationstag. Im Gegensatz zur Milch zeigte sich in Leber und Restkörper eine Sättigung der Riboflavinkonzentrationen, die bei einer Riboflavinzulage von 6 mg/kg (Leber) bzw. 10 mg/kg (Restkörper) erreicht war. Die maximalen Riboflavinkonzentrationen bei Zulagen von 4 000 mg/kg waren dabei 1,9 (Leber) bzw. 2,3 (Restkörper) mal so hoch wie bei fehlender Riboflavinzulage. Diese Befunde sprechen für eine ausgeprägte homöostatische Kontrolle der Riboflavinkonzentrationen im Organismus. Anhand von Dosis-Wirkungsbeziehungen mit den Riboflavinkonzentrationen in Leber und Restkörper als Wirkungskriterien leitete sich bei Verwendung des halbsynthetischen Futters (17,4 MJ ME/kg Trockenmasse (T), 20,8 % Rohprotein in T) ein Riboflavinbedarf von 8 bis 9 mg/kg Futter für die laktierende Ratte ab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01611397
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  • 4
    Electronic Resource
    Electronic Resource
    Lipaemia and liver composition in pregnant rats consuming olive oil and olive oil used for frying (1997)
    Springer
    European journal of nutrition 36 (1997), S. 205-213 
    Details
    ISSN: 1436-6215
    Keywords: Frying ; growth ; liver lipids ; lipaemia ; olive oil ; pregnancy ; rat ; Fritierung ; Wachstum ; Leberfett ; Olivenöl ; Schwangerschaft ; Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Um Informartionen über den Zusammenhang zwischen der Aufnahme von Fett, das zum Fritieren benutzt wurde, und dem Fetthaushalt während Perioden starken Körperaufbaus zu haben, wurde der Einfluß der Aufnahme von frischem Olivenöl (Gehalt polarer Verbindungen, 2 %; Ölsäure 78,9 mg/100 mg Öl, und Linolsäure 7 mg/100 mg Öl) und von Olivenöl, das 15 mal in Folge für das Fritieren von Kartoffeln benutzt worden war (Gehalt polarer Verbindungen 9 %; Ölsäure 75,8 mg/100mg Öl und Linolsäure 6,2 mg/100mg Öl) während der Gravidität, untersucht. Dazu wurden trächtige Wistar Ratten in zwei Gruppen geteilt, die beide eine isokalorische Diät bekamen, deren Fettanteil 15 % von frischem (unbenutztem) (P1) bzw. fritiertem (benutztem) (P2) Olivenöl stammte mit nicht trächtigen Ratten verglichen. Die Gravidität erhöhte (p〈0,01) die Futteraufnahme, das Körpergewicht, die Gewichtszunahmen und die Futterverwertung. Die Ölqualität beeinflußte dagegen diese Parameter nicht. Während der Gravidität stiegen die Serumwerte der Triglyceride (TG) (p〈0,01) und des Cholesterins (TC) (p〈0,05) an, während die der Phosphatide (PH) sanken (p〈0,01). Ein signifikanter Effekt der Ölqualität und eine Wechselwirkung zwischen Gravidität und Öl wurde für TG und PH festgestellt. Das Gewicht und der Fettgehalt der Leber der trächtigen Ratten stiegen signifikant an (p.〈0.05), Leber TC, TG und PH stiegen während der Gravidität (ungefähr um das 3-fache der Ausgangswerte), aber es traten keine signifikanten Unterschiede zwischen der Aufnahme von benutztem und nicht benutztem Öl (P2 vs P1) auf. Die Ergebnisse zeigen, daß die Aufnahme von leicht verdorbenem Olivenöl als alleinige Fettquelle der Nahrung keine besonderen Folgen für die Gravidität hat, was die Gewichtszunahme der Mütter und der Feten, die Lipämie und die Zusammensetzung des Leberfetts betrifft.
    Notes: Summary The effect of the consumption of unused olive oil (polar content, 2 %; oleic acid, 78.9 mg/100 mg oil, and linoleic acid 7 mg/100 mg oil) and olive oil used discontinuously for frying potatoes 15 times (polar content, 9 %; oleic acid, 75.8 mg/100 mg oil and linoleic acid 6.2 mg/100 mg oil) was studied in pregnant rats with the aim of better understanding the relationship between the consumption of fat used in frying and lipid metabolism during periods of intense anabolism. Trials were performed in pregnant Wistar rats, divided into 2 groups and fed isocaloric diets in which the fat content (15 % wt/wt) consisted of unused olive oil (P1) or oil previously used for frying (P2), and the results were compared with those of nonpregnant rats fed unused olive oil (NP1) and olive oil used for frying (NP2). Pregnancy increased (p〈0.01) food intake, body weight, weight gain, and food efficiency ratio (P2 vs NP2 and P1 vs NP1, respectively), but the treatment of oil included in the diets did not alter these parameters. Gestation significantly increased the serum triglyceride (TG) (p〈0.01) and total cholesterol (TC) (p〈0.05) concentrations and diminished that of phospholipids (PH) (p〈0.01). A significant effect of the type of oil consumed and a pregnancy x oil interaction on Tg and PH levels was observed. The weight of the liver and its fat content increased significantly (p〈0.05) as a result of pregnancy. Liver TC, TG, and PH increased (approximately 3 times the original values) during gestation, but no significant differences due to the intake of used or unused oil (P2 vs P1) were observed. The results indicate that the consumption of moderately altered olive oil, as the sole source of fat, does not alter the effect of pregnancy on the mothers' weight gain, lipaemia, and hepatic fat composition to any important degree.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623365
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization and cellular localization of PSG in rat testis (1997)
    Springer
    Molecular and cellular biochemistry 177 (1997), S. 229-237 
    Details
    ISSN: 1573-4919
    Keywords: pregnancy-specific b1-glycoprotein ; cDNA ; rat ; Sertoli ; Leydig ; myoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In order to establish the rat testis as a model system for studying the human pregnancy-specific b1-glycoprotein (PSG), expression and cellular distribution of PSG in rat testis were examined. Three partial PSG cDNAs, namely, rnCGM6, rnGCM7, and rnCGM8 were obtained when rat testis cDNA libraries were screened with a human placental PSG cDNA probe. Unlike the human PSGs, the rat PSGs show less nucleotide and amino acid sequence homology among family members. The rat PSGs also have multiple truncated leader sequences followed by immunoglobulin variable-like N domains while human PSGs have a single N domain. Examination of the testis, intestine, kidney, liver, lung, and muscle of male rats by reverse transcription-polymerase chain reaction (RT-PCR) with nested gene-specific primers showed that rnCGM6 was present only in the testis, while rnCGM8 was present in the testis, intestine and lung. On the other hand rnCMG7 was found in all tissues examined. Furthermore, rnCGM7 transcript was present in all somatic cells examined whereas rnCGM6 was predominantly in myoid cells and rnCMG8 in Leydig cells. These results suggest that there is cell-specificity in the expression of PSGs in the rat testis and that the rat testis is a good model for studying the biological activities of the PSGs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006811305616
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  • 6
    Electronic Resource
    Electronic Resource
    Species differences in localization of cardiac cAMP-phosphodiesterase activity: A cytochemical study (1997)
    Springer
    Molecular and cellular biochemistry 173 (1997), S. 183-188 
    Details
    ISSN: 1573-4919
    Keywords: phosphodiesterase ; cytochemistry ; myocardium ; rat ; dog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The localization of the membrane-bound cyclic 3′,5′-AMP phosphodiesterasein cardiac tissues of both, rat and dog was studied by cytochemical method.40 µm thick slices from glutaraldehyde fixed heart tissue wereincubated in the medium with cAMP as a substrate and Pb ions as a capturemetal of the reaction product. The cAMP-PDE activity in the rat ventriclewas only shown positive on the sarcolemma. Whereas, in canine ventriculartissue the cAMP-PDE activity in cardiomyocytes was shown on the sarcolemma,on the junctional sarcoplasmic reticulum and on subsarcolemmal cisternae.The results confirm differences in the localization of cAMP-PDE in dog andrat heart.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006845513962
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  • 7
    Electronic Resource
    Electronic Resource
    Rapid isolation of muscle and heart mitochondria, the lability of oxidative phosphorylation and attempts to stabilize the process in vitro by taurine, carnitine and other compounds (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 61-66 
    Details
    ISSN: 1573-4919
    Keywords: heart mitochondria ; lability ; muscle mitochondria ; oxidative phosphorylation ; stability ; taurine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract We modified the isolation procedure of muscle and heart mitochondria. In human muscle, this resulted in a 3.4 fold higher yield of better coupled mitochondria in half the isolation time. In a preparation from rat muscle we studied factors that affected the stability of oxidative phosphorylation (oxphos) and found that it decreased by shaking the preparation on a Vortex machine, by exposure to light and by an increase in storage temperature. The decay was found to be different for each substrate tested. The oxidation of ascorbate was most stable and less sensitive to the treatments. When mitochondria were stored in the dark and the cold, the decrease in oxidative phosphorylation followed first order kinetics. In individual preparations of muscle and heart mitochondria, protection of oxidative phosphorylation was found by adding candidate stabilizers, such as desferrioxamine, lazaroids, taurine, carnitine, phosphocreatine, N-acetylcysteine, Trolox-C and ruthenium red, implying a role for reactive oxygen species and calcium-ions in the in vitro damage at low temperature to oxidative phosphorylation. In heart mitochondria oxphos with pyruvate and palmitoylcarnitine was most labile followed by glutamate, succinate and ascorbate.We studied the effect of taurine, hypotaurine, carnitine, and desferrioxamine on the decay of oxphos with these substrates. 1 mM taurine (n = 6) caused a significant protection of oxphos with pyruvate, glutamate and palmitoylcarnitine, but not with the other substrates. 5 mM L-carnitine (n = 6), 1 mM hypotaurine (n = 3) and 0.1 mM desferrioxamine (n = 3) did not protect oxphos with any of the substrates at a significant level. These experiments were undertaken in the hope that the in vitro stabilizers can be used in future treatment of patients with defects in oxidative phosphorylation. (Mol Cell Biochem 174: 61–66, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006803807814
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  • 8
    Electronic Resource
    Electronic Resource
    Na+-H+ exchange inhibition at reperfusion is cardioprotective during myocardial ischemia-reperfusion; 31P NMR studies (1997)
    Springer
    Molecular and cellular biochemistry 176 (1997), S. 257-264 
    Details
    ISSN: 1573-4919
    Keywords: dimethyl amiloride ; intracellular pH ; ischemia-reperfusion injury ; 31P NMR ; sodium-hydrogen exchange ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract To help resolve the controversy as to whether or not Na+-H+ exchange is functioning during reperfusion of the ischemic myocardium we assessed the effects of dimethylamiloride (DMA, an amiloride analogue possessing selectivity for inhibition of the Na+-H+ exchanger) on cardiac function and intracellular pH during ischemia-reperfusion. Studies were performed in the presence of bicarbonate (modified Krebs-Henseleit buffer) or in the nominal absence of bicarbonate (HEPES buffer) in order to determine if similar cardioprotection and effects on intracellular pH were observed in the presence and absence of bicarbonate dependent transport processes. Isovolumic rat hearts were perfused in the Langendorff mode at a constant pressure of 80 mm Hg and subjected to 28 min total global ischemia at 37°C. Intracellular pH was determined from the pH dependent shift of the inorganic phosphate peak in 31P nuclear magnetic resonance spectra. DMA (20 µM) was infused for either 2.5 min before ischemia, for the initial 5 min of reperfusion, or at both time intervals. DMA had no effect on the intracellular pH during ischemia. Intracellular pH returned to pre-ischemic levels within 2.5 min of reperfusion in bicarbonate buffer. This normalization of pH was slower in HEPES perfusate. In both bicarbonate and HEPES perfused hearts all drug dosing regimens caused a significant increase in the recovery of mechanical function after reperfusion and slowed the recovery of intracellular pH during reperfusion. These results suggest that the Na+-H+ exchanger is activated during reperfusion of the ischemic myocardium, that this activation of the exchanger contributes to ischemia-reperfusion induced cardiac dysfunction and that administration of an inhibitor of Na+-H+ exchange at reperfusion significantly attenuates the deleterious effects of exchanger activation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006861414737
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  • 9
    Electronic Resource
    Electronic Resource
    A new technique of coronary artery ligation: Experimental myocardial infarction in rats in vivo with reduced mortality (1997)
    Springer
    Molecular and cellular biochemistry 176 (1997), S. 227-233 
    Details
    ISSN: 1573-4919
    Keywords: myocardial infarction ; coronary ligation ; ischemic heart disease ; histopathology ; rat ; animal model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In vivo models of myocardial infarction following coronary artery ligation in the rat still suffer from high early mortality and a low rate of success of myocardial infarction. This study investigated the possibility of reducing early mortality and increasing the rate of myocardial infarction by modifications of surgical techniques. Eighteen rats were divided into two groups: normal control (3 rats) and ligation (15 rats). The major modifications of surgical techniques used in this study include: (1) no exteriorization of the heart, (2) ligation of the origins of the branches rather than the main trunk of the left coronary artery, (3) removal of air from the chest after closure, (4) supplying oxygen immediately after extubation. Following surgery, the rats recovered uneventfully and 11 rats were alive after 16 weeks. One rat, with a large myocardial infarction, died 2 h after surgery. Early mortality (during surgery and 1 week after surgery) was 6.7% with a success rate of myocardial infarction of 85%. The left ventricle in the ligation group showed significant dilation relative to normal and shamoperated control hearts (317% of control hearts, p 〈 0.001). However, myocardial mass did not increase. The average infarct size was 33%. These results demonstrate that a reduction in early mortality and an increased success rate of myocardial infarction can be achieved by modifications of surgical techniques.
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    URL: http://dx.doi.org/10.1023/A:1006853112920
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  • 10
    Electronic Resource
    Electronic Resource
    In vitro effects of Celiptium and MR 14504 on mature rat Leydig cell testosterone production (1997)
    Springer
    Cell biology and toxicology 13 (1997), S. 83-94 
    Details
    ISSN: 1573-6822
    Keywords: intercalating drugs ; in vitro toxicity ; Leydig cells ; testosterone ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Percoll-purified mature rat Leydig cells have been used to evaluate the testicular toxicity of two highly potent intercalating agents (Celiptium and MR 14505). Testosterone secretion in the absence and in the presence of human chorionic gonadotropin (hCG) was measured to assess Leydig cell function. Celiptium and MR 14504 induce time- and dose-related inhibitory effects on the production of testosterone by Leydig cells, both in the presence and in the absence of hCG, whatever the concentration of hCG used. We have observed that MR 14504 is about 5 times more potent as an inhibitor of rat Leydig cell steroidogenesis than Celiptium without inducing any cell toxicity. The present study indicates that the Leydig cell is an additional potential site for the primary toxic effects of these drugs in the adult rat testis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:CBTO.0000010393.20626.18
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  • 11
    Electronic Resource
    Electronic Resource
    Comparison of amitriptyline metabolism in hepatocytes from streptozocin-induced diabetic rats and from non-diabetic rats (1997)
    Springer
    Cell biology and toxicology 13 (1997), S. 131-137 
    Details
    ISSN: 1573-6822
    Keywords: diabetes ; rat ; cell culture ; antidepressant ; kinetics ; biotransformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Biotransformation of amitriptyline (AMI) was studied at different intervals in freshly isolated hepatocytes from healthy or streptozocin-induced diabetic rats in order to investigate the influence of the diabetic state. Levels of free and conjugated AMI, demethylated and hydroxylated metabolites, were assessed by HPLC analysis. In hepatocytes isolated from diabetic rats, AMI was less completely metabolized and the demethylation reaction became more important than in non-diabetic rat hepatocytes. Although the proportions of hydroxylated metabolites decreased in diabetic rats, it always remained predominant. Furthermore, glucuronidation of metabolites was greater, especially for (Z)-10-hydroxynortriptyline in diabetic animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:CBTO.0000010398.63757.4c
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  • 12
    Electronic Resource
    Electronic Resource
    The use of primary hepatocyte cultures for the evaluation of chemoprotective agents (1997)
    Springer
    Cell biology and toxicology 13 (1997), S. 323-329 
    Details
    ISSN: 1573-6822
    Keywords: chemoprotection ; cytochrome P450 ; glutathione S-transferase ; hepatocytes ; human ; in vitro preparation ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Primary cultures of human and rat hepatocytes are widely used in pharmacotoxicological research. This model presents the advantages of retaining liver function for at least a few days, expressing both phase 1 and phase 2 enzymes, and responding to inducers. Recently we made use of primary hepatocytes to investigate the effects of chemoprotective agents on drug-metabolizing enzyme expression and activities. The treatment of rat and human hepatocytes with two chemoprotective agents, oltipraz (a synthetic derivative of 1,2-dithiole-3-thione) and sulforaphane (an isothiocyanate found in broccoli), clearly demonstrated that both of these compounds are inducers of glutathione transferases and transient inhibitors of cytochrome P450, suggesting that these two compounds could exert their chemoprotective effects by both reducing the formation of reactive metabolites of chemicals and enhancing their inactivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007491525955
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  • 13
    Electronic Resource
    Electronic Resource
    DNA ploidy and autophagic protein degradation as determinants of hepatocellular growth and survival (1997)
    Springer
    Cell biology and toxicology 13 (1997), S. 301-315 
    Details
    ISSN: 1573-6822
    Keywords: autophagy ; carcinogenesis ; hepatocyte ; liver ; ploidy ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Hepatocytes have the ability to go through specialized cell cycles, which, during normal developmental liver growth, result in the formation of binuclear and polyploid cells. In the adult rat liver, the majority of the hepatocytes (about 70%) are tetraploid, 15-20% are octoploid, and only 10-15% are diploid (about 50% in humans). One-third of the hepatocytes in either rats or humans are binuclear (with two diploid or two tetraploid nuclei). Among cultured rat hepatocytes stimulated with growth factors (EGF and insulin), one-half of the mitoses are of the binucleating type (suggesting a "quantal" mechanism), causing one-third of the postmitotic cells to become binuclear. In contrast, regenerative liver growth, induced by partial hepatectomy, is predominantly nonbinucleating. During rat liver carcinogenesis, the early populations of phenotypically altered cells (foci) are predominantly diploid, as are the later neoplastic nodules and carcinomas, which can be shown to have a regeneration-like, largely nonbinucleating growth pattern. A negative correlation between growth capacity and ploidy can be demonstrated in cultured hepatocytes, regenerating livers, neoplastic nodules, and hepatocellular carcinomas, suggesting that suppression of binucleation and polyploidization may carry a growth advantage, in addition to helping to maintain a large population of diploid, potential stem cells. Since a diploid genome is less protected against mutagenic change than a polyploid genome, diploid tumor cells may, furthermore, be more prone than polyploid cells to undergo mutation-based progression toward increasing malignancy. The ability of liver tumor promoters like 2-acetylaminofluorene, cyproterone acetate, α-hexachlorocyclohexane and methylclofenapate to induce nonbinucleating hepatocyte growth may, therefore, cooperate with the selective growth stimulation of cancer cells and cancer cell precursors to promote liver carcinogenesis. Autophagy, a mechanism for the bulk degradation of cytoplasm, contributes to intracellular protein turnover and serves to restrict cellular growth. Rat liver carcinogenesis is accompanied by a progressive reduction of autophagic capacity, preneoplastic livers having 50% and hepatocellular carcinoma cells only 20% as much autophagy as normal hepatocytes. The ascites hepatoma cell line AH-130 has virtually no autophagy during logarithmic growth, but some autophagy is turned on when the cells become growth-arrested at high cell density. Ascitic fluid from AH-130 cells is able to completely inhibit autophagy in normal hepatocytes, suggesting that the cancer cells may improve their growth ability through an autocrine, autophagy-suppressive mechanism. Hepatocytes from preneoplastic livers similarly maintain a low autophagic activity under restrictive culture conditions, thereby surviving much better than normal hepatocytes, which switch on their autophagy. In the presence of an autophagy inhibitor (3-methyladenine), normal and preneoplastic hepatocytes survive equally well, testifying to the importance of autophagy as a determinant of cell survival and growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007487425047
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  • 14
    Electronic Resource
    Electronic Resource
    Stable, recombinant expression of human insulin-like growth factor binding protein-1 (hIGFBP-1) in Chinese hamster ovary (CHO) cells (1997)
    Springer
    Cytotechnology 24 (1997), S. 193-200 
    Details
    ISSN: 1573-0778
    Keywords: CHO cells ; DHFR ; IGFBP-1 ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Stable expression of human insulin-like growth factor of binding protein-1 (hIGFBP-1)at high levels has been achieved in Chinese hamster ovary (CHO) cells by co-transfection and subsequent co-amplification of expression vectors containing the hIGFBP-1 cDNA and a dihydrofolate reductase (DHFR) cDNA gene into DHFR-deficient cells. Stepwise selection of the DHFR+ transformants in increasing concentrations of methotrexate (MTX) generated cells which had high copy numbers of the hIGFBP-1 gene (around 100 copies in cells amplified in medium containing 100 nM MTX). Expression of hIGFBP-1 in mixed clones was found to increase with increasing copy number and an apparent correlation between intra- and extracellular levels of hIGFBP-1 produced by these cells was observed. It was further observed that continuous cultivation over eight months in medium supplemented with 100 nM MTX increased the production of hIGFBP-1 25 times. The productivity did not increase further after five more months cultivation in MTX containing medium. A subcloning of this cell line gave clones with an even higher productivity. Further amplification in 500 nM or 1 uM MTX did not increase the hIGFBP-1 production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007999512662
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  • 15
    Electronic Resource
    Electronic Resource
    Effect of vagotomy on heart rate in intact and sympathectomized rats of different ages (1997)
    Springer
    Bulletin of experimental biology and medicine 124 (1997), S. 639-641 
    Details
    ISSN: 1573-8221
    Keywords: rat ; vagus ; sympathectomy ; heart ; stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A comparative analysis of temporal variations of the heart rate variability after cutting and stimulation of the vagus in sympathectomized and intact rats showed that changes in heart rate after bilateral vagotomy in sympathectomized rats are opposite to those in the controls. It is postulated that postganglionic fibers modulate sympathetic influence on intracardiac parasympathetic neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02445048
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  • 16
    Electronic Resource
    Electronic Resource
    Age-specific vagus regulation of the chronotropic function of the heart in desympathized and intact rats (1997)
    Springer
    Bulletin of experimental biology and medicine 123 (1997), S. 609-611 
    Details
    ISSN: 1573-8221
    Keywords: rat ; vagus nerve ; desympathization ; heart ; stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Comparison of the effects of stimulation of vagus nerves in intact and desympathized rats showed differences in the variation pulsogram parameters in different age groups. A similar time course of variation pulsogram parameters in response to vagus nerve stimulation was observed in normal and experimental rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458094
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  • 17
    Electronic Resource
    Electronic Resource
    Effect of platinum-containing cytostatics on rat progeny (1997)
    Springer
    Bulletin of experimental biology and medicine 124 (1997), S. 1075-1077 
    Details
    ISSN: 1573-8221
    Keywords: rat ; platidiam ; progeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Pathological changes in internal organs are seen in some offspring of intact females and males treated with platidiam 1 month before mating. One case of malformation was found in the progeny of cytostatic-treated females. High embryonal mortality is noted in animals treated with cytostatics 3 and 6 months before mating. Delayed ossification is observed in some animals of almost all experiments groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02445665
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  • 18
    Electronic Resource
    Electronic Resource
    Spermatogenesis in rats after injection of the antitumor drug vepeside (1997)
    Springer
    Bulletin of experimental biology and medicine 124 (1997), S. 1194-1197 
    Details
    ISSN: 1573-8221
    Keywords: rat ; spermatogenesis ; vepeside
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Stable morphological changes and disorders of spermatogenesis develop in the testicles of Wistar rats during 30 days after a single injection of vepeside in the maximum tolerance dose. By the end of experiment the morphology of the testicles gradually normalizes, but some quantitative parameters characterizing spermatogenesis remain shifted. The detected disorders are caused by the damaging effect of the drug on the cells of all layers of spermatogenic epithelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02445117
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