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At least 253 records · Page 14Linked to original sources

PubMed1995

The mobilization and tissue distribution of beta-carotene in the rat by the venous injection method.

Now it is known that beta-carotene (beta-carotene) has other important biological functions in addition to the role of vitamin A precursor. The various epidemiological studies suggested that high beta-carotene intake might reduce the incidence of the cancer risk. Although several studies are under way to find biological evidence for the epidemiological results, the mechanism of action of beta-carotene is still unknown. As the first step to elucidate the biological functions of beta-carotene, we investigated the mobilization and the distribution of all-trans-beta-carotene in the rat. Because it was reported that the rat did not absorb the intact form of beta-carotene, we injected a beta-carotene suspension intravenously (dose; 2.0 mg/rat). After injection, a high amount of beta-carotene (about 1.5 mg-2.0 mg) accumulated in the lung very rapidly (within 5 min). By this method, the time-dependent mobilization and distribution of beta-carotene in the rat was as follows: all-trans-beta-carotene was accumulated in the lung then moved to the liver, was distributed in adipose tissues (after 1 week), pancreas (after 2 weeks), and muscle tissue or testis (after 3 weeks).

Absorption↗

PubMedDate not supplied

Metabolism and tissue distribution of mono-2-ethylhexyl phthalate in the rat.

The absorption, distribution and metabolic excretion of mono-2-ethylhexyl [7-14C]phthalate (MEHP) were studied in the rat. This compound was readily absorbed from the gastrointestinal tract. Radioactivity following intravenous administration of 14C-MEHP was rapidly distributed in all tissues, with the highest levels occurring in the liver, kidney, and urinary bladder. Excretion of radioactivity was rapid and approximately 80% of the dose was eliminated 24 hr after oral administration, 72% in the urine and 8% in feces. MEHP was extensively metabolized after oral administration, and the major urinary metabolites were identified as an alcohol, a ketone, and an acid resulting from the side-chain oxidation of MEHP. A trace of o-phthalic acid was also identified.

Animals↗

PubMed1985

[Tissue distribution of cefminox in beagle dogs].

A new cephamycin antibiotic, cefminox (MT-141, CMNX), was intravenously infused into Beagle dogs at a dose of 40 mg/kg in order to study it's distribution to various tissues. The following results were obtained. The maximum serum concentration of CMNX observed at the end of the infusion period was 102.3 micrograms/ml, and then the concentration decreased. The biological half-life of CMNX in serum was 37.0 minutes. This half-life was similar to the results of previous studies with Beagle dogs and rabbits. The maximum concentrations in tissues and body fluids were highest in B-bile followed by kidney, urinary bladder, serum, liver, vagina, uterus, pericardiac fluid, trachea, ovary, lung, gallbladder, parotid gland, heart, tonsil, thymus, spleen, pancreas, aqueous humor and cerebrospinal fluid, in that order and not detected in brain. The maximum concentrations in gallbladder, B-bile, pericardiac fluid and cerebrospinal fluid were found at 1-2 hours after administration. In other tissues and body fluids, they were obtained at the end of the infusion period. The area under the tissue concentration curve (AUC) was highest in the urinary bladder followed by the kidney, vagina, liver, uterus, gallbladder, trachea, ovary and lung, in that order. These results suggest that CMNX is useful for various infectious diseases in these tissues. The pharmacokinetic parameter (K1i/K2i) derived from serum and tissue concentrations using the deconvolution method well correlated to maximum tissue concentrations.

Animals↗

PubMed1988

Monoclonal antibodies which react with bovine T-lymphocyte antigens and induce blastogenesis: tissue distribution and functional characteristics of the target antigens.

In this study we report on the tissue distribution and functional characteristics of bovine T-cell differentiation antigens recognized by the monoclonal antibodies (mAbs) IL-A26, IL-A27, and IL-A28. All three mAbs are able to stimulate proliferation of peripheral blood mononuclear cells (PBM) and inhibit proliferation of responder cells in mixed leucocyte cultures (MLC). MAbs IL-A27 and IL-A28 are believed to react with the same molecule, which is different to that recognized by IL-A26 as determined by a number of criteria. MAbs IL-A27 and IL-A28 inhibit binding of one another, but not of IL-A26. MAbs IL-A27 and IL-A28 react with 25% of thymocytes confined to the medulla, whereas IL-A26 reacts with approximately 80% of thymocytes, including medullary and cortical populations. MAbs IL-A27 and IL-A28 react with thymocytes which express BoT4 or BoT8 singularly, whereas IL-A26 reacts with all cells which express BoT4 or BoT8, either singularly or dually, in addition to all thymocytes which react with IL-A27/28. Only IL-A26 inhibits spontaneous sheep erythrocyte (E)-rosette formation by bovine T cells. Based on tissue distribution and functional characteristics, IL-A26 is believed to recognize the bovine homologue of CD2, designated BoT2, whereas IL-A27/28 reacts with a mature T-cell antigen. Cells reactive with the mAbs constitute approximately 60% of bovine PBM. Using these mAbs in dual immunofluorescence analyses, at least three populations of bovine T cells are demonstrable in PBM. The majority of T cells are BoT4+ or BoT8+ and also react with IL-A26/27/28. A second small population of PBM is negative for BoT4 and BoT8 but is IL-A26/27/28+. A third population (less than 5%) is BoT4-/BoT8-/ILA27/28- but reacts with IL-A26.

Animals↗

PubMed1985

Allylamine cardiovascular toxicity: V. Tissue distribution and toxicokinetics after oral administration.

We studied the uptake, tissue distribution, toxicokinetics, and excretion of allylamine by giving rats [14C]allylamine (1.5 microCi/kg; 150 mg/kg) by gavage. Rats were killed at intervals up to 2 h, and multiple tissues were sampled. Aorta showed the highest counts of 14C-label at most times (5-10-fold higher than most other organs, 100-fold higher than blood), although a minority of aortas had very low counts. Coronary arteries dissected from the hearts showed consistently higher 14C-label than myocardium. Liver counts, which were high at 5 min, decreased rapidly; kidney counts slowly increased until 45 min, then decreased rapidly, consistent with an excretory function for this organ. Counts of 14C-label were lower in all other organs, including lung, skeletal muscle, brain, testes, pancreas, adrenal, spleen, fat, and blood. Toxicokinetic study showed a very rapid absorption rate and short half-lives (less than 1 h) for those organs which reasonably fit a toxicokinetic one-compartment model. 14C-label was rapidly excreted in the urine; approximately 60% of the dose given was recovered by 24 h. No counts were found in feces. These studies indicate that allylamine--or its metabolite(s)--has a unique predilection for elastic and muscular arteries, such as aorta and coronary arteries. This relatively specific cardiovascular toxin acts as a highly polar, highly water soluble substance, which is rapidly absorbed from the gastrointestinal tract, has a short half-life in most tissues, and is rapidly excreted in the urine. The actual mechanisms by which allylamine injures tissue, especially in view of its rapid sequestration in vascular tissue, remain to be uncovered.

Administration, Oral↗

PubMedDate not supplied

Tissue distribution and lung localization of [14C]azelastine in guinea pigs.

Tissue distribution was performed in male guinea pigs that received a single oral dose of 1 mg/kg [14C]azelastine. Determination of 14C concentrations by liquid scintillation counting in 16 tissues and by whole-body autoradiography showed preferential uptake of the radioactivity by the lung. The liver had a higher and all other tissues had lower concentrations of 14C than the lung. The lowest 14C concentrations were in the eyes and brain. Light microscopy autoradiography of lung and trachea sections indicated localization of 14C, possibly in alveolar macrophages. The radioactivity cleared completely from lung tissue, as well as from other tissues within 48 hr.

Animals↗

PubMed2000

Prediction of in vivo tissue distribution from in vitro data 1. Experiments with markers of aqueous spaces.

PURPOSE: The aim of this study was to evaluate the ability of an in vitro method of tissue distribution to accurately predict total water and extracellular aqueous spaces using marker compounds urea and inulin. METHODS: Slices (50-200 mg) of all the major tissues in the rat were incubated with Hanks/HEPES pH7.4 buffer containing 14C-urea and 3H-inulin for 2 h at 37 degrees C. Tissue weight was noted before and after incubation and the tissue-to-buffer ratios determined. RESULTS: 14C-Urea Kp estimates were generally greater than total tissue water due to tissue swelling, which varied widely among the tissues, up to 41% in muscle. In most cases, Kp values were much closer to in vivo values after correcting for the 14C-urea in the imbibed media (Kpcorr). The method was able to distinguish between 14C-urea and 3H-inulin Kp values and indicated that inulin occupied a smaller space than urea, which for the majority of tissues corresponded to the extracellular space. CONCLUSIONS: The Kp(corr) values for 14C-urea and Kp for 3H-inulin were consistent with total tissue water and extracellular space for the majority of tissues studied, indicating their suitability as marker compounds for checking the viability of this in vitro method for estimating tissue distribution.

Animals↗

PubMed2001

Biochemical characterization and tissue distribution of human SULT2B1.

The human hydroxysteroid sulfotransferase (SULT) family is comprised of two subfamilies, SULT2A1 and SULT2B1. We characterized the substrate specificity, in vitro biochemical properties, and tissue distribution patterns of human SULT2B1a and SULT2B1b. In contrast to the wide substrate specificity of SULT2A1, SULT2B1a and SULT2B1b specifically catalyzed the sulfonation of 3beta-hydroxysteroids with high catalytic efficiency. Both SULT2B1 enzymes also sulfonated dihydrotestosterone. In vitro studies revealed that the biochemical properties of SULT2B1a and SULT2B1b were not significantly different from each other. However, tissue expression analysis suggested that they are differentially regulated. In contrast to the limited tissue distribution of SULT2A1, SULT2B1 was detected in a variety of hormone-responsive tissues including placenta, ovary, uterus, and prostate. The catalytic activity toward dehydroepiandrosterone and dihydrotestosterone, biologically important androgens, coupled with expression in prostate suggests that SULT2B1 may play a novel regulatory role that protects against the mitogenic effects of androgens.

Amino Acid Sequence↗

PubMed1991

Generation of a monoclonal antibody against avian small dermatan sulfate proteoglycan: immunolocalization and tissue distribution of PG-II (decorin) in embryonic tissues.

Chick embryonic skeletal muscle synthesizes three major types of proteoglycans: large chondroitin sulfate proteoglycans, small dermatan sulfate proteoglycans and small heparan sulfate proteoglycans. A monoclonal antibody has been raised which recognizes the small dermatan sulfate proteoglycan. Immunoblot analysis of a partially purified preparation of skeletal muscle proteoglycans indicates that the antibody reacts with a molecule which migrates with an estimated Mr of 100,000. Prior treatment of the proteoglycans with chondroitinase results in immunostaining of a species of estimated Mr 45,000. These values for the intact proteoglycan and its core protein suggest that the antibody is directed against a proteoglycan of the PG-II or decorin class. Immunohistochemistry indicates a widespread distribution of the proteoglycan, which is localized in connective tissue septa of skeletal and cardiac muscle, dermis, tendon, bone, perichondrium and cornea. Immunoblot analysis of the proteoglycan core proteins from these tissues demonstrates that the antibody recognizes the same 45,000-dalton band in each tissue. The widespread tissue distribution is also consistent with the antibody being directed against an epitope of PG-II. Neither the glycosaminoglycan chains nor N-linked oligosaccharides are required for reactivity and the antibody cross-reacts with other avian material, but not mammalian. This antibody, which has been designated CB-1, reveals developmental stage-specific changes in the deposition of PG-II in embryonic limb bud and skeletal muscle.

Animals↗

PubMed2006

Study on pharmacokinetics and tissue distribution of norvancomycin in rats by CE with electrochemical detection.

In this paper, we developed a sensitive and simple method to study the pharmacokinetics and tissue distribution of norvancomycin (NVCM) in experimental animals by using CE with electrochemical detection. Pharmacokinetics investigation was performed by the collection of blood samples at timed intervals following administration of NVCM. Pharmacokinetic parameters were calculated by the 3P87 pharmacokinetic program. The elimination half-life of NVCM was 42.4742 min with a clearance rate of 0.0233 mL x kg(-1) x min(-1). Additionally, drug distribution was studied by measuring the NVCM levels in kidney, lung, stomach, intestine, spleen, heart, liver, and cerebrum. Electrophoresis conditions such as buffer solution, working potential, separation voltage, and sampling time were also discussed. The linear range was from 0.8 to 540 microg/mL with a correlation coefficient of 0.9991. The detection limit was 0.3 microg/mL. This method was for the first time applied to study the pharmacokinetics and tissue distributions of NVCM in experimental animals.

Animals↗

PubMed1990

Effects of preparing and ligand-binding methods of small unilamellar liposomes on their blood elimination and tissue distribution in rats.

The effects of two methods of preparing small unilamellar vesicles (SUV) (detergent removal or sonication) on their in vivo elimination and tissue distribution was investigated in rats. The SUV prepared by either method had the same size distribution and lipid composition (egg yolk phosphatidylcholine/cholesterol/dipalmitoyl phosphatidylethanolamine or palmitic acid = 20/10/0.3, molar ratio). Three types of SUV made by either method were prepared. These contained one of three different surface ligand-binding functional groups (N-hydroxysuccinimide ester of palmitic acid, NHSP; glutaraldehyde-phosphatidylethanolamine, GA-PE; N-[4-(p-maleimidophenyl)butyryl]phosphatidylethanolamine, MPB-PE). SUV prepared by detergent removal were eliminated slowly from the circulation, and exhibited a low liver uptake and little leakage of [3H]inulin. There was no significant difference in elimination of the NHSP-SUV, GA-SUV or MPB-SUV prepared by detergent removal and their tissue distribution was similar. In contrast, the sonicated SUV were eliminated from the circulation much more rapidly mainly by liver uptake. The leakage of [3H]inulin from sonicated SUV into urine was relatively large. When sonicated control-SUV were prepared in the presence of the antioxidant, alpha-tocopherol (alpha-T-SUV), which reduces lipid peroxidation during sonication, the alpha-T-SUV were eliminated slowly with only a low liver uptake. Our results indicate that the rapid elimination and greater liver uptake of sonicated SUV is partly due to lipid peroxidation during preparation. These findings have relevance to the use of liposomes as a drug delivery system.

Animals↗

PubMed2004

Tissue distribution of concentrative and equilibrative nucleoside transporters in male and female rats and mice.

Concentrative nucleoside transporters (Cnts) and equilibrative nucleoside transporters (Ents) have essential physiological functions and are important in disposition of anticancer and antiviral nucleoside analogs. Information on tissue distribution of Cnts and Ents in rodents is sparse. Thus, the present study aimed to determine the distribution of Cnt1-3 and Ent1-3 transcripts in 19 tissues of Sprague-Dawley rats and C57BL/6 mice of both genders. These six transcripts were quantified using the branched DNA signal amplification assay. Cnt1 transcripts were highest in small intestine, followed by kidney and testes, with similar expression in both species. Cnt2 mRNA was expressed highest in the small intestine of both rats and mice, intermediate in liver of rats but not in mice, and lower in thymus and spleen of both species. Cnt3 mRNA has marked species differences, with the highest expression in lung of rats but uterus of mice. Ent1 mRNA was most highly expressed in testes and lung of both species. Ent1 mRNA was highly expressed in liver and pituitary of mice, but not in rats. Ent2 mRNA was highly expressed in testes and brain of both species. Ent3 mRNA was highest in kidney, followed by testes, in both species. Significant gender differences were observed in kidney (mouse) and heart (rat). These studies demonstrate that in general, tissue distribution of Cnt and Ent is similar in rats and mice. However, a few important species and gender differences do exist, which could be responsible for related differences in efficacy and toxicity of substrates for these transporters.

Animals↗

PubMed1989

Long-term tissue distribution and steady state activity ratios of 232Th and its daughters in rats after intravascular injection of Thorotrast.

To estimate the absorbed dose in the critical organs of Thorotrast patients, it is necessary to know not only the distribution and concentration of 232Th but also its daughter nuclides in the body. The present investigation was undertaken in order to clarify the long-term 232Th tissue distribution and steady state activity ratios between subsequent daughters in the critical tissues using about 30 Wister male rats, as a basis for estimating absorbed doses. The tissue distribution of thorium was examined by means of an autoradiography of the whole body and/or the gamma-ray spectrometry at various times during 2 to 24 months following injection. The concentrations of daughter nuclides in tissues were determined by repetitive gamma examination over a period from 1 hr to 35 days after being sacrificed. The data indicate (1) that approximately 90% of injected Thorotrast is retained in the body for a prolonged period, but about 50% of radium and 10% of radon produced from thorium are eliminated from the body, (2) that the mean steady state activity ratios of 224Ra and 212Pb to 228Th for liver are 0.56 and 0.28, and 0.54 and 0.16 for spleen, 0.58 and 0.82 for lungs, respectively, and (3) that the parent 228Th is translocated to the bone.

Animals↗

PubMed1998

Quantitative structure-pharmacokinetics relationships: II. A mechanistically based model to evaluate the relationship between tissue distribution parameters and compound lipophilicity.

The tissue-to-unbound plasma distribution coefficients (Kpus) of 14 rat tissues after i.v. administration of nine 5-n-alkyl-5-ethyl barbituric acids, determined in a previous study, were used to identify a model of the relationship between tissue distribution and lipophilicity of the homologs, expressed in terms of their octanol to water partition ratio, P. Based on mechanistic considerations and assumptions, the parameter model was expressed as Kpu tau = fw.tau [1 + a tau (nPt.tau)Pb tau], where fw.tau is the tissue water content. (nPt. tau) is the binding capacity of the tissue, n is the number of the binding sites, a tau and b tau are the parameters of the relationship Ka tau = a tau Pb tau; and Ka tau is the binding association constant of each tissue. The parameter model was linearized and fitted to the predetermined Kpu values, yielding correlation coefficients ranging between .940 and .997. The predictive performance of the parameter model was evaluated using a leave-one-out procedure with subsequent computation of the mean prediction error (ME = measurement of the prediction bias) and the square root of the mean squared prediction error (RMSE = measurement of the prediction accuracy). The ME varied between -22.48 and 61.14%, indicating a slight tendency for overpredicting. The RMSE was between 24.73 and 102% for the individual tissues across the different homologs; and between 28.33 and 85.2% for the individual homologs across the different tissues. The apparently high Kpu prediction errors, when translated through the low sensitivity of the barbiturate whole-body physiologically based pharmacokinetic model, established previously, leads to predicted tissue concentration-time profiles within 5 to 20% of the original ones. Therefore, it is concluded, that the identified mechanistically based model is a good predictor of the tissue-to-unbound Kpus in the rat tissues.

Animals↗

PubMedDate not supplied

Pharmacokinetics and tissue distribution of gentiopicroside following oral and intravenous administration in mice.

The pharmacokinetics and tissue distribution of Gentiopicroside (GPS), one of the major active components of the Gentiana species of medicinal plants, was studied following oral and intravenous administration in mice. The distribution of GPS in mice after oral and intravenous doses could be fitted to a two-compartments open model. The serum half-life of GPS was 6.1 h and 2.8 h for intravenous and oral administration, respectively. The Tmax of GPS after oral administration was 0.50 h, and the bioavailability was 39.6%. The AUC gradient in individual tissues following intravenous administration was kidney >serum >liver >spleen >lung >thymus >fat >heart >muscle >stomach >intestinal >brain. The MRT gradient was muscle >serum >lung >spleen >lung >intestinal>heart >stomach >brain >liver >thymus >kidney >fat. Overall the data show that GPS could be absorbed rapidly in mice, but with a low bioavailability, and could distribute to tissues extensively, but was generally cleared quickly with short MRTs. The study demonstrates the need for repeated dosage, or better, a slow release formulation as an ideal means of administering GPS.

Administration, Oral↗

PubMed1982

Chelation in metal intoxication X: Influence of different polyaminocarboxylic acids and thiol chelators in the excretion and tissue distribution of 54Mn in rat.

The influence of some selected polyaminocarboxylic acids and thiol metal binding agents on the urinary and faecal excretions of 54Mn and on the tissue distribution of 54Mn in 54MnCl2 administered rats was studied to find a suitable chelating drug for Mn poisoning. HEDTA, CDTA, DTPA and TTHA were highly successful in enhancing the excretion of 54Mn and reducing the tissue levels of 54Mn in rats. The thiol chelators viz. D L-penicillamine, N-acetyl D L-penicillamine and DMS could neither influence the excretion nor the tissue distribution of 54Mn suggesting poor affinity of the metal towards sulfhydryl groups.

Amino Acids↗

PubMed1976

Autoradiographic and tissue distribution studies on a nitrovinylfuran derivative (SQ 18506 14C) in S. mansoni infected mice.

Autoradiographic and tissue distribution studies of SQ 18506 14C were carried out on 13 Swiss albino mice. Infection was done by I.P. route with 50 to 60 cercaria of S. mansoni (puerto Rican strain) per animal. The safe single i.v. dose of a solution containing one mg of SQ 18506 dissolved in 0.06 ml dimethylsulfoxide was 0.003 ml/g b.w. of mice. Schistosome autoradiograms were clearly demonstrated one day after that dose injected in each mouse 50 days post-infection. However, hepatic autoradiograms were visible 14 days after 2 doses of our drug to each infected mouse. The higher the concentration of SQ 18506 14C in the culture medium the darker were the schistosomes in the autoradiograms and the greater their total d.p.m/mg. Tissue distribution studies after 2 1/2 doses of our drug/mouse revealed that schistosome total d.p.m/mg dry-weight was 50 times more than that of its liver. The latter d.p.m/g wet-weight was slightly higher than that of one ml of mouse blood.

5-Amino-3-((5-nitro-2-furyl)vinyl)-1,2,4-oxadiazol↗

PubMed1993

Molecular cloning, sequencing, tissue distribution, and functional expression of a Na+/H+ exchanger (NHE-2).

The present studies demonstrate cloning, sequencing, tissue distribution, and functional expression of a Na+/H+ exchanger which was isolated from a rat intestinal cDNA library. The cloned cDNA recognizes two transcripts in poly(A)+ RNA from the stomach, jejunum, ileum, liver, large intestine, and uterus. Based on deduced amino acid sequences, this clone shares sequence homology with the other known Na+/H+ exchanger isoforms (NHE-1, NHE-3, and NHE-4) except for its 5' end. Overall, the protein exhibits 47.8%, 41.2%, and 56.2% amino acid sequence identity to NHE-1, NHE-3, and NHE-4, respectively. The hydropathy profile of the predicted protein shows 10 transmembrane domains, suggesting a protein with transport characteristics. The tissue distribution differs from that of the other Na+/H+ exchanger isoforms. The cDNA hybridizes to two closely related transcripts in the mRNA of these tissues, which suggests that the predominant transcript of this clone is alternatively spliced. Transfection of this cDNA into Na+/H+ exchanger-deficient mutant fibroblasts (PS120 cells) results in functional Na+/H+ exchange activity. These data suggest that we have cloned a member of the Na+/H+ exchanger family with tissue-specific expression. We suggest the designation of NHE-2 for this Na+/H+ exchanger.

Amino Acid Sequence↗