The effect of vitamin D3 and 25-hydroxycholecalciferol on intestinal transport of calcium in vivo and in vitro

Zusammenfassung 8 Stunden nach Injektion von 25-Hydroxycholecalciferol bei rachitischen Ratten steigerte sich der Kalzium-Transport des Duodenum in vivo wie auch in vitro bedeutend. Während dieser Zeit war Vitamin D₃, wirkungslos. 24 h nach der Injektion stimulierten beide Verbindungen in ähnlichem Masse den Kalzium-Transport.     

Suppression of carcinogen-induced rat mammary tumor formation by Actinomycin D

Zusammenfassung Sprague-Dawley-Ratten, die eine kombinierte Belastung mit 7,12-Dimethylbenz()anthrazen und Aktinomyzin D überleben, weisen eine drastisch erniedrigte tastbare Tumorinzidenz auf. Kontrolltiere erhielten nur das Karzinogen.     

The action of various vitamin D3 metabolites on calcium and phosphorus metabolism in chick embryo calvariae

Chick embryos from vitamin D-deficient hens given physiological doses of 1,25-dihydroxyvitamin D3 or 24,25-dihydroxyvitamin D3 or both become severely hypocalcemic, hyperphosphatemic and fail to hatch as compared to those derived from hens given 25-hydroxyvitamin D3 or 24,25-difluoro-25-hydroxyvitamin D3. Calvariae from the former contain less mineral and on incubation in vitro produce significantly lower calcium and higher phosphate concentration in the medium than do the calvariae derived from the embryos of hens supported on 25-hydroxyvitamin D3 or 24,24-difluoro-25-hydroxyvitamin D3.     

The action of various vitamin D3 metabolites on calcium and phosphorus metabolism in chick embryo calvariae

Summary Chick embryos from vitamin D-deficient hens given physiological doses of 1,25-dihydroxyvitamin D₃ or 24,25-dihydroxyvitamin D₃ or both become severely hypocalcemic, hyperphosphatemic and fail to hatch as compared to those derived from hens given 25-hydroxyvitamin D₃ or 24,25-difluoro-25-hydroxyvitamin D₃. Calvariae from the former contain less mineral and on incubation in vitro produce significantly lower calcium and higher phosphate concentration in the medium than do the calvariae derived from the embryos of hens supported on 25-hydroxyvitamin D₃ or 24,24-difluoro-25-hydroxyvitamin D₃.     

Lag period of action of 25-hydroxycholecalciferol on bone collagen metabolism in vitamin D deficient rats

Zusammenfassung Nachweis, dass die Freisetzung von Hydroxyprolin bei Knochenfragmenten bereits 6 h nach i.v. Verabreichung von 2,5 g 25-Hydroxycalciferol signifikant erhöht war, während eine entsprechend zugeführte Dosis von Vitamin D₃ erst 13 h später deutlich wirkte.

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We thank Dr.E. Kodicek and Dr.E. M. Cruickshank of Dunn Nutritional Laboratory for help and criticism, and Mrs.J. Jobbágy for technical assistance.     

Adaptation of intestinal amino acid transport

Zusammenfassung An evertierten Dünndarmsäcken (proximales Jejunum) erwachsener Ratten, die zwei Wochen lang eine proteinarme (13% Kasein) oder proteinreiche (88% Kasein) Diät erhalten hatten, wurde der aktive intestinale Transport vonl-Leuzin undd-Galaktose untersucht. Proteinreiche Ernährung führte zu einer Stimulierung desl-Leuzin-Transports, während derd-Galaktose-Transport dadurch unbeeinflusst blieb. Diese Befunde sprechen für eine spezifische Adaptation des intestinalen Aminosäurentransports an den Proteingehalt der Nahrung.     

Effect of (+)-catechin on renal and intestinal transport

Summary The ability of dog renal cortex slices to accumulate -methyl-glucoside or glycine is enhanced by the flavonoid (+)-catechin at a concentration of 3.5 mM. This stimulatory effect is apparently due to a decreased rate of efflux of either substrate. On the other hand, the uptake of p-amino-hippuric acid and N¹-methyl-nicotinamide is inhibited by (+)-catechin. The drug at the same concentration is without action on amino-acid transport by guineapig intestine in vitro.This study was supported by grants from Zyma S.A., Nyon. We are grateful to MmesH. Capt andP. Ganguillet and MlleD. Mettraux for their skilful technical assistance.     

Effect of (+)-catechin on renal and intestinal transport.

The ability of dog renal cortex slices to accumulate beta-methyl-glucoside or glycine is enhanced by the flavonoid (+)-catechin at a concentration of 3.5 mM. This stimulatory effect is apparently due to a decreased rate of efflux of either substrate. On the other hand, the uptake of p-amino-hippuric acid and N1-methyl-nicotinamide is inhibited by (+)-catechin. The drug at the same concentration is without action on amino-acid transport by guinea-pig intestine in vitro.     

Phosphorylation and uphill intestinal transport of thiamine,in vitro

Riassunto L'impiego di tiamina-¹⁴C, con la tecnica dei sacchetti rovesciati di intestino di ratto, ha permesso di dimostrare che, durante il trasporto contro gradiente in vitro, la tiamina viene fosforilata dal tessuto intestinale. Gli inibitori metabolici e gli analoghi strutturali della tiamina che ne inibiscono la fosforilazione del pari ne riducono il trasporto netto. Ciò dimostra che il trasporto intestinale della tiamina è strettamente connesso con la sua fosforilazione.     

Local action of vitamin A on amphibian limb regeneration

Summary Axolotl forearms isolated from upper arm tissue either surgically or by local irradiation regenerate excessive structures after vitamin A treatment. This demonstration excludes the possibility of regeneration being altered by enhanced cellular migration and thus indicates that vitamin A respecifies cells close to the site of amputation.     

The influence of sodium transport on glucose transport by anin vitro intestinal preparation

Riassunto Vengono riportati i dati ottenuti sul trasporto di sodio e di glucosio attraverso l'intestino isolato di ratto, perfuso con soluzioni isotoniche a diverso contenuto di sodio. Da questi dati appare che non solo il trasporto di sodio dipende dalla concentrazione di sodio nel liquido mucosale, ma anche il transporto di glucosio. Si prospetta l'ipotesi, inoltre, che il passaggio di sodio dalla mucosa alla sierosa sia necessario sopratutto per il trasferimento del glucosio dalle cellule al liquido serosale.     

Isoelectric focusing of the serum vitamin D transport protein (DBP) and the polymorphism of Gc protein. Significance in anthropology]

The authors confirm the analogy between Gc and DBP as a result of analytic studies by isoelectrofocusing and labeling of Gc with 3H vitamin D3. The presence of a relationship between Gc polymorphism and the amount of sunshine in a given region is discussed.     

On the action of vitamin C on the neuromuscular junctions

Summary High concentrations of ascorbic acid produce complete blockage of the transmission of nervous stimuli on the isolated neuromuscular preparation of phrenic nerve-hemidiaphragm of the rat.     

Demonstration of vitamin D3 metabolism inmytilus edulis

Summary Radiolabeled vitamin D₃ was converted into several polar metabolites upon incubation with tissue homogenates from the common musselMytilus edulis. Chromatographic analysis indicated that the metabolites have chromatographic mobilities different from those of known standards. The results suggest that vitamin D₃ is metabolized in mussels via pathways that differ from the vertebrate systems.Acknowledgments. The authors thank Dr Pirjo Rantamäki for the mussels and F. Hoffmann-La Roche & Co. for supplying the vitamin D₃ metabolite standards. This work was supported by a grant from the Magnus Ehrnrooth Foundation to T. K.     

Specificity of action of phospholipases of rat intestinal mucosa]

The total homogenate of rat intestine is devoid of C or D phospholipase activity. At pH 6,5 in the presence of phosphatidylcholines, it exhibits a B phospholipase activity and in the presence of exogen lysophosphatidylcholines an A1 lysophospholipase activity. At pH 8,5 the intestinal mucous membrane of a rat shows an isolated A2 phospholipase activity.     

Net transport of water and solutes by anin vitro rat intestinal preparation

Riassunto Vengono riportati i dati ottenuti sul passaggio netto di acqua e di soluti attraverso l'intestino isolato di ratto, perfuso con soluzione isotonica o ipertonica per aggiunta di solfato di sodio. È stato determinato anche il crioscopico dei liquidi raccolti e delle soluzioni di perfusione. Da questi dati appare che il passaggio di acqua dipende dall'istituirsi di un gradiente di concentrazione per il trasporto attivo di soluti nello stesso senso.Il solfato di sodio eserciterebbe sui tessuti intestinali una azione impermeabilizzante, riducendo così il trasporto netto totale di soluti.