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At least 919 records · Page 51Linked to original sources

PubMed1980

Fracture healing under factor XIII medication.

Following application of factor XIII for 3 weeks bone healing was studied in Sprague-Dawley rats on the 20th postoperatively day qualitatively (radiographs, scintigraphy) and quantitatively (determination of callus thickness, of bone mineral content, and scintillation counting). No significant difference could be detected between animals treated with factor XIII and animals which served as controls. Therefore, a stimulating effect of factor XIII upon bone healing can not be expected in case of a normal factor XIII serum-level. The application of factor XIII is indicated only in high risk patients with a low factor XIII serum-level.

Animals↗

PubMed1987

The postnatal development of stimulated deoxyglucose uptake into the mouse cochlea and the inferior colliculus.

The effect of acoustic stimulation on the postnatal development of deoxyglucose uptake into the mouse cochlea and the inferior colliculus was evaluated. Animals between postnatal day 4 and 20 were separated into four different groups depending on their age. Tritiated deoxyglucose was injected intraperitoneally into each animal and tracer uptake was quantitated by microdissection of the tissues and scintillation counting. Acoustic stimulation at a noise level of 100 dB (A) resulted in supra-normal levels of deoxyglucose uptake for all auditory tissues during postnatal days 13, 14, and 15. The lateral wall tissues, which are non-sensory and non-neuronal, also increased deoxyglucose uptake following acoustic stimulation in a manner that paralleled the uptake by the sensory structures. Serum radioactivity and glucose levels remained unchanged during postnatal development, with these parameters remaining stable with acoustic stimulation.

Acoustic Stimulation↗

PubMed1980

Repetitive DNA sequences in methotrexate- and methasquin-sensitive and -resistant Chinese hamster cell lines.

DNA purified from a Chinese hamster cell line of lung fibroblast origin (DC83F) was analyzed by density gradient centrifugation and by gel electrophoresis after restriction endonuclease digestion in order to fractionate discrete repetitive fractions within the total DNA. No obvious satellite DNAs were resolved using the CsCl or Ag-Cs2SO4 density gradient conditions described herein. However, analysis of the digestion products of a battery of restriction endonucleases indicated that three of these enzymes, EcoR1, HaeIII, and XhoI, yielded discrete fragments which could be visualized with EtBr staining or identified by scintillation counting of [3H]DNA. DNAs from several highly (greater than or equal to hundredfold increased resistance) antifolate-resistant sublines of DC-3F, characterized by a large homogeneously staining region (HSR) in the chromosome complement, were examined with both techniques and compared to the parental, antifolate-sensitive cell line DNA. The density gradient profiles and electrophoretic patterns of restriction endonuclease digests were identical among all the cell lines examined and were indistinguishable from those of the parental DC-3F DNA.

Animals↗

PubMed1981

Determination of plasma catecholamines by means of radioenzymatic labelling and high pressure liquid chromatographic separation.

0.05 ml plasma samples are incubated with 3H-S-adenosylmethionine and catechol-O-methyl-transferase. The resulting methodoxy derivatives are extracted, the extracts separated by high pressure liquid chromatography and the metanephrine fractions collected. Evaluation is performed by liquid scintillation counting of radioactivity in the respective fractions. The following performance criteria are presented: precision, accuracy, detectability (40 pg/ml for adrenaline and noradrenaline, 130 pg/ml for dopamine), linearity and day-by-day variation. Comparison with a standard method shows an excellent correlation for adrenaline and noradrenaline.

Adult↗

PubMed1982

Sympathetic Nerve Stimulation on the perfused rat heart. Affinities of N-methylatropine and pirenzepine at pre- and postsynaptic muscarine receptors.

Rat isolated hearts with the sympathetic nerves attached were perfused with (-)-3H-noradrenaline in order to label the storage vesicles of the adrenergic nerves. Release was induced either by electrical stimulation of the nerves (3 Hz, 1 min) or by perfusion with high K+ solution (54 mM). The overflow of 3H-noradrenaline and its metabolites was determined by liquid scintillation counting after separation of the compounds by column chromatography. The experimental conditions ensured a minor contribution of 3H-metabolites to the evoked total tritium overflow. The release of 3H-noradrenaline evoked by nerve stimulation or high K+ solution was decreased in the presence of the muscarinic agonist, methacholine, N-methylatropine reversed the inhibition completely. Thus, the rat heart contains inhibitory muscarine receptors modulating noradrenaline release from adrenergic nerve fibres. In order to compare the presynaptic muscarine receptors with postsynaptic muscarine receptors in one and the same organ, the pA2 values of N-methylatropine and pirenzepine at both of these sites were measured. The antagonism of methacholine-induced inhibition of 3H-noradrenaline overflow was determined as the presynaptic parameter. pA2 values of 9.61 for N-methylatropine and 6.63 for pirenzepine were found. The methacholine-induced inhibition of the atrial tension development of isolated left rat atria paced at 2Hz was measured as a postsynaptic parameter. pA2 values of 9.90 for N-methylatropine and 6.69 for pirenzepine were found. The postsynaptic pA2 values did not differ from the presynaptic affinity constants indicating that neither substance revealed differences in structure between neuronal and myocardial muscarine receptors in the rat heart.

Animals↗

PubMed1983

The isotope effect of tritium in 3H-(-)-adrenaline with very high specific activity.

Initial rates of the extraneuronal uptake of 3H-(-)-adrenaline of very high specific activity were determined in the perfused rat heart, fluorimetrically for unlabelled and by scintillation counting for labeled amine. The presence of nearly four tritium substituents in the adrenaline molecule slowed uptake by a factor of 5.56. The isotope effect of tritium appears to increase in direct proportion to the number of tritium substituents per molecule. It is concluded that 3H-catecholamines of very high specific activity are unsuitable for studies of the uptake and metabolism of 3H-catecholamines.

Animals↗

PubMed1979

5'-Nucleotidase: solubilization, radiochemical analysis, and electrophoresis.

5'-Nucleotidase (5'-NT, E.C. 3.1.3.5) of cultured human and rodent cells was rendered soluble using the zwitterionic detergent Zwittergent 314. Optimal activity of 5'-NT was obtained when sonicated cells were incubated in solutions containing 0.75% (w/v) Zwittergent. A method was developed for the determination of the activity of 5'-NT in which the unutilized substrate, [14C]-AMP, was precipitated with lanthanum chloride and the soluble [14C]-adenosine was measured by scintillation counting. 5'-NT isozymes were separated using agarose gel electrophoresis and isoelectric focusing in polyacrylamide gel. The zones of enzyme activity were established by precipitation of unutilized [14C]-AMP with LaCl3, removal of soluble [14C)-adenosine by washing gels in water, and autoradiography. The zones of 5'-NT appeared as clear zones on darkened X-ray film. When analyzed by agarose gel electrophoresis, fibroblasts derived from human skin and rat liver produced a single zone of 5'-NT activity. The 5'-NT isozyme of rat cells migrated faster than that of human cells and was easy to distinguish. The presence of detergent in the sample and in the gel enhanced enzymatic activity and improved the separation of the isozymes. Isoelectric focusing resolved 5'-NT of human fibroblasts into two molecular forms, one of which focused in the region of pH 6 and the other at pH5.

Animals↗

PubMed1976

Tissue distribution of 14C-heteronium bromide: radioactivity levels at different time intervals after oral administration in the rat.

The tissue distribution of radioactivity after oral administration to rats of 14C-heteronium bromide is measured by liquid scintillation counting and the results expressed as specific activity and percentage of administered radioactivity. From the data obtained in blood, liver, kidney. stomach, duodenum, cecum, large intestine and stool some conclusions can be drawn. Heteronium bromide undergoes a rapid systemic absorption, the radioactivity being present as early as 15 min from the administration, in all the tested organs. The blood levels show two peaks: one at 120 min and a second at 360 min. This diphasic behaviour can be explained either by the presence of an active enterohepatic circulation, as indirectly indicated by the data from liver and duodenum, or by a transient shift of the molecule from blood to other tissues, rich in polysulfuronic acids. The principal route of excretion is represented by the kidney, where consistent levels are reached at 120 min, while the intestinal route becomes evident at 240 min and reaches its maximum at 720 min. The complete metabolic cycle of the compound is long lasting, since in all the tested tissues, marked radioactivity levels are still present after 720 min. The pharmacokinetic profile obtained, suggesting a long persistence of the drug and/or of its metabolites in the organism, is in agreement with previous pharmacodynamic data showing a long lasting action for heteronium bromide.

Administration, Oral↗

PubMed1982

Intact epidermal cell assay for ornithine decarboxylase activity.

A procedure measuring the ornithine decarboxylase (ODC) activity and polyamine formation of intact neonatal mouse epidermal cells in culture has been developed and tested. Basal cells prepared from neonatal mouse epidermis were plated on round 15-mm Lux coverslips, placed in Costar 24 well culture clusters and grown at 32 degrees C in M-199 + 13% fetal bovine serum. Before assay the cells were rendered permeable to ornithine 14C and ODC inhibitors using the buffer described by Berger et al. [3]. The slides, covered with adhering cell layers, were then placed in vials, covered with assay buffer and assayed intact for ODC activity. The ODC reaction was terminated by addition of citric acid to the buffer and the amount of 14CO2 released was determined by scintillation counting of a center well filled with trapping agent. The baseline ODC activity of the intact cells was 500-1,000 pmol 14CO2/mg protein/45 min. The validity of this ODC assay procedure using intact neonatal mouse keratinocytes was tested by use of three specific ODC inhibitors and by measuring the formation of polyamines from uniform labeled ornithine. The results indicated that authentic ODC activity was measured and preserved in this intact neonatal mouse epidermal cell assay. This technique holds promise for future studies of epidermal cell regulation of ODC and polyamine synthesis and studies of the multiple ornithine metabolites and conjugates formed, using a highly manipulable in vitro system.

Animals↗

PubMed1983

Hormonal control of hamster ear sebaceous gland lipogenesis.

The sites and hormonal control of lipogenesis in hamster ear sebaceous glands are reported. Sebaceous lipogenesis was determined in ear biopsies by incubation with glucose and tracer concentrations of 14C-acetate in buffer. The 14C-labeled lipids were saponified, extracted, and determined by liquid scintillation counting. Histologically, the ears contained many sebaceous glands. The glands of male animals were much larger and more heavily lipid-stained than glands from females. Lipogenesis was almost entirely confined to the sebaceous glands in the dermal stroma. Lipogenesis was considerably higher in ear biopsies from male hamsters than from female, castrate male, or hypophysectomized male hamsters. In contrast to published data using hypophysectomized rats, where dihydrotestosterone potently and testosterone only weakly increased sebum secretion, both testosterone and dihydrotestosterone potently increased lipogenesis in the ears of hypophysectomized male hamsters. Dihydrotestosterone was somewhat more potent than testosterone in the hamster. Hypophyseal hormones do not appear to be essential for androgen stimulated lipogenesis in the hamster. In female hamsters, 5 alpha-androstane-3 alpha, 17 beta-diol, testosterone, dihydrotestosterone, 4-androstene-3,17-dione, and 5 alpha-androstane-3,17-dione produced dose-dependent increases in lipogenesis. From this and other studies, it is suggested that androgens other than dihydrotestosterone could be physiologically important in man and animals in stimulating lipogenesis in sebaceous glands.

Androgens↗

PubMed1976

The uptake and subcellular distribution of radio-labeled metabolites of digoxin in the isolated perfused guinea-pig heart.

Cardiac glycosides like digitoxin and digoxin with three digitoxoside sugar residues have been reported to undergo step-wise degradation to yield the corresponding genins, and the importance of the digitoxoside side-chain for the pharmaco-dynamics property of cardiac glycosides has also been suggested. A sytematic study was therefore undertaken on the cleavage products of digoxin. Digoxigenin-bis-digiitoxoside (with two sugar residues) digoxigenin-monodigitoxoside (with one sugar residue) and digoxigenin (with no sugar) were compared with the parent compound, digoxin. The radio-labeled compounds were perfused through isolated guinea pig hearts using 10-7 M concentration in the perfusion medium for a fixed period of 64 min followed by an 8 min period of wash-out with normal medium. The uptake and sub-cellular distribution of the drugs were thereafter measured scintillation counting. All the compounds produced postive inotropic responses, the mondigitoxoside producing the greatest effect, digoxigenin next in order of inotropic response magnitude, the bis-digitoxoside produced the least effect, and digoxin was intermediate between the genin and bis-digitoxoside. The uptake of the monodigitoxoside was the highest, and in general, the quantitative uptake was related to the inotropic response. The greatest binding of each digitoxoside was found in the microsomal fraction. Both mechanical activity and uptake of all four drugs were uniformly reduced by an increase in potassium concentration in the perfusion medium.

Animals↗

PubMed1984

Pharmacokinetics of tolfenamic acid: disposition in bile, blood and urine after intravenous administration to man.

To study its pharmacokinetics and especially microCi/100 mg was infused i.v. in 8 patients with a T-tube inserted in the common bile duct at choledocholithotomy 7-10 days prior to the study. Bile was collected in fractions by continuous suction over a 24 h period. Blood samples were taken and urine collected up to 48 h after the dose. Tolfenamic acid and its metabolites were separated by TLC and were quantitated by liquid scintillation counting. The pharmacokinetics of tolfenamic acid could be described by a two compartment open model with V1 of 3.67 +/- 0.681 and VSS of 8.0 +/- 1.01. The total plasma clearance of tolfenamic acid averaged 106 +/- 8 ml/min and t1/2 beta was 1.38 +/- 0.32 h. A three compartment open model was required to describe the kinetics of total 14C. The plasma clearance of total 14C was 15.4 +/- 3.9 ml/min and its terminal half life averaged 19.0 +/- 4.1 h. The long half-life was caused by the slow elimination of tolfenamic acid metabolites. Four metabolites were measured in plasma and bile. The principal metabolites in bile were glucuronide/sulphate conjugates of hydroxylated derivatives of tolfenamic acid. The recovery of tolfenamic acid in bile was 1.1 +/- 0.3% of the dose, whereas the recovery of total 14C was 18.6 +/- 4.9%. The biliary clearances of tolfenamic acid and total 14C were 1.2 +/- 0.3 and 5.0 +/- 2.1 ml/min, respectively. Thus, biliary excretion plays a considerable part in the pharmacokinetics of tolfenamic acid.

Aged↗

PubMed1982

Metabolism of pindolol in patients with renal failure.

Increased metabolism of pindolol in renal impairment has previously been suggested by pharmacokinetic calculations. The present study was a pharmacokinetic and metabolic investigation in 7 patients with severe renal impairment (endogeneous creatinine clearance below 5 ml/min). All the patients received pindolol 5 mg t.d.s. 5 days. On the sixth day, after an overnight fast, 14C-pindolol 5 mg was given orally as a solution to drink. Blood samples were taken for up to 72 h and urine was collected at intervals up to 96 h for measurement of unchanged pindolol by a fluorimetric method and total radioactivity by liquid scintillation counting. Metabolites in blood and urine were analysed after separation by HPLC. It was found that the plasma levels following a single dose of 14C-pindolol were similar to those observed in healthy volunteers, but the elimination half-life was slightly increased u tp 11.5 h. The observed steady state plasma concentrations of pindolol were twice as high but they are still in the therapeutic range of 10 to 100 ng/ml. Therefore, the dose of pindolol could have been reduced by a factor 2, but the reduction was not essential. No active metabolite of pindolol was found in plasma or urine, but elimination of the metabolites was decreased. The elimination half-life following multiple doses was prolonged compared to normal and it was quite comparable to that found fort pharmacodynamic half-life in renal patients. The discrepancy between the present findings and the previous results for metabolism and pharmacodynamic half-life was probably due to the sensitivity of the fluorimetric assay of pindolol.

Aged↗

PubMed1975

[Fumaric acid monoethylester: Effect on DNA-synthesis and preliminary findings in experimental studies in animals (author's transl)].

The incorporation of 14C-Thymidin into DNA of cultured human lymphocytes is depressed by added fumaric acid monoethylester (FSME) depending on the dosage of FSME. The decreased radioactivity in DNA as measured by scintillation counting is paralleled by a concomitant decrease in the labelling index in autoradiograms. Decreasing radioactivity is therefore due to a lower number of DNA synthesizing cells. No selective inhibition of proliferation during one of the cell cycle phases was observed. Especially a G2-block known from other cytostaties is absent. A mean dosis of 6.88 mg FSME per g body weight administered intraperitoneally is lethal to mice. The animal die from diffuse necroses of heart muscle cell. Alterations of other organs are less prominent. At lower doses of FSME the morphology of the organs investigated is altered to a smaller degree.

Animals↗

PubMed1975

The intrarenal distribution of 125I-albumin in the Syrian hamster.

The intrarenal distribution of radioiodinated human serum albumin (125RISA) after intravenous injection was studied in Syrian hamsters by scintillation counting and frozen section autoradiography. After 15, 30 and 60 min the virtual plasma albumin space in the renal cortex of the hamster represented 6.49, 7.13, and 8.06 percent respectively of the kidney tissue volume. From the cortex to the renal papilla the albumin space increased to about 30 percent of the tissue volume. In comparison to this the albumin space in the renal cortex of the rat was about 20% and in the renal papilla about 33% (11). Frozen section autoradiography indicated that the distribution of radioalbumin in the renal cortex of the Syrian hamster is limited mainly to the kidney vessels, being especially noticeable in the glomerular capillaries. Toward the papilla increasingly greater (mainly extratubular) activity could be observed not only intravascularly but also interstitially. In the cortex of the rat kidney, on the other hand, radioactive albumin was accumulated (probably by filtration and reabsorption) predominantly in the proximal tubular epithelium. Wtithin 30 min thekidneys of the rat excreted mor than 10 times as much 125I than the hamster kidneys. These results (substantially less cortical accumulation and urinary excretion of radioalbumin in the Syrian hamster) indicate that, in contrast to the rat, obviously much less albumin is filtered (and then accumulated by proximal reabsorption) by the Syrian hamster glomeruli. This suggests that the Syrian hamster kidney is more suitable than the rat kidney for determining the interstitial, cortical, albumin space.

Animals↗

PubMed1985

Nasal bioavailability and systemic effects of the glucocorticoid budesonide in man.

Budesonide, a topically potent glucocorticoid, was administered to 4 healthy volunteers by i.v. infusion and by nasal instillation of 100 micrograms tritium-labelled drug. Plasma was analyzed by liquid chromatography plus scintillation counting of collected fractions. After i.v. administration the plasma clearance was 0.921/min and the apparent volume of distribution was 2.81/kg. After nasal administration, the time to reach the peak plasma level was approximately 30 min, and the systemic availability was 102%. Budesonide had marginal effects on plasma cortisol and white blood cell counts either after i.v. or nasal administration. Thus, nasally instilled budesonide in solution is rapidly and completely absorbed from the nasal mucosa. The systemic effects after this clinically recommended nasal dose were negligible.

Administration, Topical↗

PubMed1976

Correlated changes of Balbiani ring expansion and secretory protein synthesis in larval salivary glands of Chironomus tentans.

Salivary glands of various stages of the last larval instar of Chironomus tentans were quantitatively analyzed with respect to the expansion of their Balbiani rings (B1, B2, B3) by a fast green staining procedure as well as to the rate of synthesis of their secretory proteins (S1, S2, S3) by a scintillation counting procedure of electrophoretic fractions. The extent of expansion of B1, B2 and B3 correlates positively with the rate of synthesis of S3, S2 and S1, respectively. With B1 and S3 these parameters undergo a parallel and developmentally specific change being rather depressed in intermolt, and particularly in diapausing animals.

Animals↗

PubMed1984

Selective retrograde axonal transport of free glycine in identified neurons of Aplysia.

The specific retrograde axonal transport of free glycine within the identified neurons R3-14 of Aplysia californica was studied. The soma of the R3-14 neurons are located in the parietovisceral ganglion and their axons project down the branchial nerve to end in a large peripheral field. Using a double-chambered apparatus, the peripheral tissue was incubated in medium containing a 3H-amino acid for 4-48 hr, while the nerve and ganglion were isolated and perfused with plain or chemically altered medium. The nerve and ganglion were then either rapidly frozen for scintillation counting or fixed for autoradiography. When 3H-glycine was used, radioactivity entered the nerve rapidly, reached the ganglion in 3 hr, and was transported largely (greater than 80%) in the free amino acid form [trichloroacetic acid (TCA) soluble]. The right parietovisceral hemiganglion accumulated up to nine times more radioactivity than the left hemiganglion, reflecting the presence of the R3-14 axons and soma. Two phases of radioactivity were observed, a fast component moving at about 3 mm/hr and a slower (but larger) component moving at about 0.4 mm/hr. Light microscope autoradiography on nerves containing 3H-glycine revealed that the R3-14 axons accounted for more than 30% of the total label in the nerve but occupied less than 7% of the total cross-sectional area of the axonal core. Electron microscope autoradiography showed a close association of silver grains and dense core vesicles in the R3-14 axons. Retrograde axonal transport of free glycine was inhibited by (in decreasing order of effectiveness) mercuric chloride, vinblastine, colchicine, Nocodazole, and 2,4-dinitrophenol (2,4-DNP). Comparative studies of other amino acids [3H-leucine, 3H-serine, 3H-glutamic acid, 3H-gamma-aminobutyric acid (3H-GABA), and 3H-alanine] showed that 3H-glycine is the only amino acid that is rapidly axonally transported in large quantities within the R3-14 axons. This work demonstrates, for the first time, that a free amino acid, glycine, is transported in the retrograde direction within a select group of axons. The significance of this transport of glycine is discussed in relation to its use as a neural messenger by neurons R3-14.

2,4-Dinitrophenol↗