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PubMed1975

Transformation of 3H-dopamine during transport from CSF to hypophysial portal blood.

The capacity of the hypothalamus to transport dopamine from brain tissue into hypophysial portal blood was investigated. One hour after injection 10 muCi of 3H-dopamine into a lateral ventricle of male rats, radioactivity was present in the brain, in the anterior pituitary gland, and in systemic plasma. The highest concentration of radioactivity was found in the hypothalamus, whereas the lowest was found in systemic plasma. The cerebrum and systemic plasma contained over 50% of the dose injected, whereas the anterior pituitary gland contained no more than 0.2%. Three doses of 3H-dopamine (0.1, 1, 1nd 10 muCi) were injected into a lateral ventricle, and hypophysial portal and arterial blood were collected at 7 mu1/min for two hours. Ten min after injection, radioactivity was detected in hypophysial portal blood, reached a peak within 15-20 min, and then declined gradually to attain a concentration similar to that in arterial blood. Portal and arterial plasma and tissue extracts from rats injected intraventricularly with 3H-dopamine were subjected to gel filtration on a Sephadex G-10 comumn and to paper electrophoresis. The hypothalamus as well as the cerebrum contained several radiolabeled substances one of which appeared to behave like 3H-dopamine. However, no free 3H-dopamine was evident at this time either in blood or in the anterior pituitary gland. The results of chromatography and electrophoresis of dialyzed portal plasma indicate that much of the radioactivity was bound to macromolecules (probably plasma proteins) larger than 10,000-12,000 molecular weight. When the radioactive compound was dissociated from the macromolecule with perchloric acid, the dissociated compound did not behave as free 3H-dopamine as judged by gel filtration and electrophoresis. It is concluded that a transformation of 3H-dopamine occurred during passage from the CSF to blood and that no 3H-dopamine was present in portal blood. A large portion of the radioactivity was bound to plasma macromolecules.

Animals↗
PubMed1975

Thyrocalcitonin injection to rats increases the liver inorganic phosphate.

The mechanism of the hypophosphatemic effect of thyrocalcitonin (TCT) is uncertain and may involve removal of inorganic phosphate (P1) from the plasma by heretofore unidentified organs. Rats, 192 g. thyroparathyroidectomized 16-24 h earlier, received 100 MRC mU TCT or vehicle (V) SC and 100 muCi 32PO4 iv. One h later plasma and tissue samples were collected. Compared to rats which received V, TCT-treated rats had lower plasma P1 (-0.36 plus or minus 0.08 mumol/ml, P smaller than 0.001) and Ca, higher liver P1 (+0.66 plus or minus 0.19 mumol/g, P smaller than 0.01) and unchanged red blood cell and rectus abdominus P1. TCT had no significant effect on the amount of perchloric acid soluble phosphate in any of the tissues. TCT-treated rats had lower plasma 32P1 (cpm/ml) and higher liver 32P1 (cpm/g) with no significant changes in specific activity (SA). TCT caused a small decrease in muscle 32P1 SA. There were no significant changes in the 32P (cpm/g) or 32P SA of the acid soluble phosphate fraction of any of the tissues. The results suggest that a portion of the hypophosphatemic effect of TCT can be accounted for by the increased P1 level in the liver.

Animals↗
PubMed1992

Identification and characterization of insulin-like growth factor receptors on adult rat cardiac myocytes: linkage to inositol 1,4,5-trisphosphate formation.

Cultured cardiac myocytes from adult Sprague-Dawley rats express both insulin-like growth factor-I (IGF-I) receptors and insulin-like growth factor-II/mannose 6-phosphate (IGF-II/Man6P) receptors and respond to IGF-I with a dose-dependent accumulation of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and inositol 1,4-bisphosphate [Ins(1,4)P2]. Specific binding of [125I]IGF-I to isolated membranes from cultured cardiac myocytes amounted to 1-1.2%. Binding of [125I]IGF-I was inhibited by unlabeled IGF-I at nanomolar concentrations and insulin at much higher concentrations. These data suggest that IGF-I binds to its own receptor on rat cardiac myocytes. Competitive binding studies using isolated membranes from cardiac myocytes and [125I]IGF-II showed 2-4% specific binding. Binding of [125I]IGF-II was inhibited by IGF-II and much less potently by IGF-I and insulin. Immunoglobulin G (IgG) 3637 (an IgG directed against the IGF-II/Man6P receptor) partially inhibited binding of [125I]IGF-II whereas nonimmune IgG did not. Affinity cross-linking studies with [125I]IGF-II and cardiac myocyte membranes and subsequent analysis of the ligand-receptor complex using SDS-PAGE and autoradiography showed a radiolabeled band of approximately 250 kilodalton (kDa). The formation of the [125I]IGF-II-receptor complex was inhibited by incubation with IGF-II and IgG 3637 but not by insulin or nonimmune IgG. Western blotting of protein extracts from cultured cardiac myocytes was performed using IgG 3637 and an immunoperoxidase technique for the visualization of the IGF-II/Man6P receptor protein. A specific band at 220 kDa under nonreducing conditions was detected on the blots, providing further evidence for the expression of the IGF-II/Man6P receptor by cardiac myocytes. The effect of IGFs on the accumulation of inositol phosphates was measured by HPLC analysis of perchloric acid extracts from myo-[3H]inositol-labeled cultured cardiac myocytes. IGF-I (50 ng/ml) stimulated the accumulation both of Ins(1,4,5)P3 and Ins(1,4)P2 after 30 sec by 43% and 63%. IGF-II (up to 500 ng/ml) had no significant effect on inositol phosphate accumulation under the same conditions. However, in the presence of millimolar concentrations of Man6P, IGF-II (500 ng/ml) also increased Ins(1,4,5)P3 accumulation by 59%. We conclude that cardiac myocytes from adult rats express IGF receptors and respond to IGFs with the accumulation of Ins(1,4,5)P3 and Ins(1,4)P2. This effect seems to be mediated by an IGF-I receptor-specific pathway.

Animals↗
PubMed1978

Metabolism of 19-hydroxyandrostenedione in human subjects. Urinary excretion of conjugates.

A mixture of [19-3H]hydroxyandrostenedione and [14C]androstenedione was administered intravenously to 3 women and urine was collected. Only negligible radioactivity could be extracted from the untreated urine. Most of the 14C but only 11% of the 3H was rendered solube in organic solvents by beta-glucuronidase. [3H-19]hydroxyandrostenedione was recovered from this fraction. The conjugates remaining in the urine were extracted into CHCl3 as their pyridinium salts. After solvolysis of the extract with HCLO4 in tetrahydrofuran, neutral metabolites were obtained. Substances extractable from water with organic solvents were obtained by solvolysis of the conjugates with perchloric acid in tetrahydrofuran. [3H-19]hydroxyandrostenedione was identified by isotopic dilution as the major product of solvolysis. Thus, 19-hydroxyandrostenedione undergoes conjugation with glucuronic acid and probably sulfuric acid, most likely at C-19. The major urinary metabolite is the sulfate-like conjugate. Reduction in ring A is less important than for other steroids.

Adult↗
PubMed2003

N-acetyl-aspartate, total creatine, and myo-inositol in the epileptogenic human hippocampus.

BACKGROUND: Mesial temporal lobe epilepsy (mTLE) is characterized by hippocampal atrophy, decreased N-acetyl-aspartate, and a low N-acetyl-aspartate/total creatine ratio, often attributed to neuron loss and gliosis. Qualitative studies reported that N-acetyl-aspartate content was significantly lower in hippocampal sclerosis. OBJECTIVE: It was proposed to measure the effects of neuron loss and gliosis on the hippocampal content of N-acetyl-aspartate, total creatine, and myo-inositol in mTLE. METHODS: Twenty hippocampal specimens were obtained during temporal lobectomy and frozen quickly. Perchloric acid extracts of the small metabolites were prepared and analyzed by proton MRS at 11.75 T. Adjacent samples were used for cell counts. RESULTS: There were no significant associations between hippocampal neuron loss and the cellular content of N-acetyl-aspartate, total creatine, or myo-inositol, despite more than a threefold difference in neuron loss and a twofold increase in glial density. Metabolite concentrations varied two- to fourfold. Variation in the cellular content of total creatine accounted for more than three-quarters of the rank-order variance of the N-acetyl-aspartate concentrations. There were no associations between myo-inositol and N-acetyl-aspartate or total creatine. Overall, mean N-acetyl-aspartate levels were below those reported by in vivo MRS studies of control subjects. CONCLUSIONS: These data suggest that decreased N-acetyl-aspartate in mesial temporal lobe epilepsy reflects altered mitochondrial metabolism, not merely neuron loss or gliosis. It is hypothesized that the altered N-acetyl-aspartate and creatine metabolism could reflect mitochondrial dysfunction or proliferation of immature glial cells that could contribute to the epileptogenic state.

Adolescent↗
PubMed1989

High-field proton magnetic resonance spectroscopy of human cerebrum obtained during surgery for epilepsy.

We analyzed specimens of histologically normal human cerebrum obtained at surgery for medically refractory epilepsy using proton magnetic resonance spectroscopy. Perchloric acid extracts of anterolateral temporal lobe cortex contained greater concentrations of creatine, N-acetylaspartate, gamma-aminobutyric acid, alanine, and glutamate than the under lying white matter, which contained more acetate. Frontal and temporal lobe specimens composed of both gray and white matter failed to show statistically significant differences in the concentrations of creatine, N-acetylaspartate, alanine, aspartate gamma-aminobutyric acid, glutamate, glycine, taurine, threonine, valine, acetate, choline, beta-hydroxybutyric acid, inositols, lactate pyruvate, or succinate.

Adult↗
PubMed2004

Taurine detection by proton magnetic resonance spectroscopy in medulloblastoma: contribution to noninvasive differential diagnosis with cerebellar astrocytoma.

OBJECTIVE: We sought to evaluate whether taurine detection in short-echo (20 ms) proton magnetic resonance spectroscopy contributes to the noninvasive differential diagnosis between medulloblastoma and cerebellar astrocytoma in children and young adults. These two types of tumor have very different prognoses and may be difficult to differentiate by neuroradiological or clinical means. METHODS: Single-voxel proton magnetic resonance spectra of tumors were acquired at 1.5 T in 14 patients with biopsy-proven primary cerebellar tumors (six medulloblastomas, seven astrocytomas, and one mixed astroependymoma) using short-echo time (20 ms) and long-echo time (135 ms). For taurine assignment, qualitative analysis was performed on short-echo time spectra and results were compared in vitro with spectra of model solutions. Perchloric acid extracts of postsurgical tumor biopsies were performed in two medulloblastoma cases. RESULTS: Taurine detection was demonstrated in all patients with medulloblastoma and in none of those with astrocytoma. We were unable to ascertain any relationship between taurine and metastatic spread within the medulloblastoma group. CONCLUSION: Medulloblastomas characteristically seem to show taurine detectable in vivo by short-echo proton magnetic resonance spectroscopy, which may help to discriminate medulloblastoma from cerebellar astrocytoma.

Adolescent↗
PubMed1978

Labelling of human resting lymphocytes by continuous infusion of [3H]thymidine. I. Characterization of cytoplasmic label.

After continuous 3H-TdR infusion in vivo or incubation with 3H-TdR in vitro human blood lymphocytes were examined by light-microscopic and electron-microscopic autoradiography. Using relatively long autoradiographic exposure times (50--300 days) not only nuclear but also cytoplasmic labelling was visualized, the cytoplasmic label being present in up to 96% of the cells. The cytoplasmic label was predominantly associated with the mitochondria and was removed from the cells nearly completely by treatment with DNase but not with RNase or cold perchloric acid. It is concluded that this cytoplasmic label mainly represents 3H-TdR incorporated into mitochondrial DNA which is continuously renewed in an average turnover time of 14 days or less. This value is compatible with a turnover time of 11 days for mitochondrial DNA in mammalian cells reported in the literature.

Autoradiography↗
PubMed1990

Cytoplasmic pool of histone H1 in mammalian cells.

Two types of cell populations, nondividing mouse liver cells and exponentially growing Friend erythroleukemia cells, were studied for the presence of a histone H1 pool in the cytoplasm. Purified cytoplasmic fractions were extracted with 5% perchloric acid and the resulting protein preparation was characterized by two types of electrophoresis, gel filtration, peptide mapping, ELISA and immunoblotting. The occurrence of significant quantities of H1 in isolated cytoplasmic fractions was confirmed by indirect immunofluorescence on whole cells. The existence of a cytoplasmic pool of H1 contrasts with the lack of detectable amounts of core histones in the cytoplasm. This indicates that the observed H1 pool is not just a reflection of its cytoplasmic synthesis but probably has some functional significance.

Animals↗
PubMed1993

Studies on zoospore attracting activity. II. Synthesis of isoflavones and their attracting activity to Aphanomyces euteiches zoospore.

Nineteen isoflavones were synthesized and their attracting activity to Aphanomyces euteiches zoospore were investigated. Isoflavones (1, 2, 4, 16 and 19) with an unsubstituted B ring were synthesized by the oxidation of corresponding 2'-hydroxychalcones with thallium (III) nitrate trihydrate in methanolic perchloric acid. A hydroxyl group at the C-5 position in isoflavones was necessary for strong attraction to A. euteiches zoospore. The introduction of an additional hydroxyl group at the C-7 or C-4' position strengthened the attracting activity. Moreover, the methylation of the C-7 hydroxyl group strengthened the attracting activity, but the methylation of the C-4' hydroxyl group slightly weakened it. The naturally occurring isoflavones (9 and 10), which were reported to possess estrogen activity, showed moderate attracting activity.

Chalcone↗
PubMed1996

Assay for tryptophan hydroxylase activity in rat brain by high-performance liquid chromatography with fluorescence detection.

A highly sensitive and selective liquid chromatographic (HPLC) method with post-column fluorescence detection has been developed for the determination of tryptophan 5-monooxygenase activity in rat brain tissue homogenate. 5-Hydroxytryptophan, formed enzymatically from tryptophan (incubation time, 20 min), is extracted with perchloric acid and determined by HPLC. Detection is performed fluorometrically after post-column derivatization by a reaction with benzylamine in the presence of potassium hexacyanoferrate (III). The lower limit of detection for 5-hydroxytryptophan formed enzymatically is 100 fmol at a signal-to-noise ratio of three.

5-Hydroxytryptophan↗
PubMed2006

An efficient synthesis of 2-benzoxepines from Morita-Baylis-Hillman adducts using heterogeneous recyclable catalysts.

2-Benzoxepines have efficiently been synthesized from Morita-Baylis-Hillman adducts, alkyl 3-aryl-3-hydroxy-2-methylenepropanoates by treatment with HCHO catalyzed by silica supported perchloric acid (HClO4.SiO2) or Amberlyst-15 in CH2Cl2 under reflux for a short period of time (1.5-2.5 h). The catalyst can be recovered and recycled. The antibacterial properties of the new 2-benzoxepines were studied but no activity was found.

Anti-Bacterial Agents↗
PubMed1994

[Highly sensitive analytical procedure for methotrexate and its main metabolite 7-hydroxymethotrexate in serum by high-performance liquid chromatography].

Recently, methotrexate (MTX) low dose therapy (5-10 mg/m2) has been used for the treatment of patients with rheumatoid arthritis. Hence a practical and sensitive high-performance liquid chromatographic method for the determination of MTX and its main metabolite 7-hydroxymethotrexate (7-OH-MTX) in human serum has been studied. After deproteinization with perchloric acid followed by the addition of pH 5.0 acetate buffer, the serum sample was purified by solid-phase extraction on a Sep-Pak C18 cartridge. The analyte was chromatographed on a reversed-phase Inertsil ODS-2 column using a phosphate buffer-acetonitrile at pH 3.0 system as the mobile phase, and the effluent from the column was monitored at 303 nm. Gradient elution was employed to increase the sensitivity for 7-OH-MTX. A good linear relationship between peak height and concentration was found for the two compounds in the range 2.5 to 100 ng/ml of the human serum, and the detection limits were about 1 ng/ml for the two compounds. The day-to-day coefficients of variation assay were 2.3% (20 ng/ml) and 4.4% (100 ng/ml) for MTX and 4.6% (20 ng/ml) for 7-OH-MTX. The present method was successfully applied to the analysis of the serum after a single oral administration of MTX 2.5 mg tablet to male dogs. MTX was rapidly absorbed, reached to the maximal level at about 1.4 h and thereafter decreased monoexponentially with a half-life of about 1.4 h. A metabolite, 7-OH-MTX was not detected in the serum up to 24 h post dose.

Administration, Oral↗
PubMed1975

A double column procedure for the simultaneous estimation of norepinephrine, normetanephrine, dopamine, 3-methoxytyramine and 5-hydroxytryptamine in brain tissue.

A double column procedure was devised for simultaneous estimation of norepinephrine, normetanephrine, dopamine, 3-methoxytyramine, and 5-hydroxytryptamine in brain tissue. Columns of aluminum oxide were placed on columns of Amberlite CG-50 by use of a specially devised column holder so that the effluent from the upper columns could flow directly into the lower ones. Perchloric acid extracts of brain samples were passed through the doubled columns after the pH was adjusted with K2CO3. Norepinephrine and dopamine in the extracts were adsorbed on aluminum oxide in the upper columns while normetanephrine, 3-methoxytyramine, and 5-hydroxytryptamine were retained by Amberlite CG-50 placed under the aluminum oxide columns. The amines adsorbed on both columns were eluted in a small volume of dilute HC1 and each of the amines was determined fluorometrically. Some modifications were incorporated into the existing methods for developing fluorescence from the amines to increase the sensitivity. The recovery rate throughout the entire procedure for the authentic amines added to brain homogenates was in the neighborhood of 90% or higher with little column to column variation. The procedure was tested in the estimation of the five amines on various parts of single brains of normal or pargyline-treated rats.

Animals↗
PubMed1983

Biotransformation of coumarin derivatives. (2). Oxidative metabolism of 7-alkoxycoumarin by microsomal enzymes and a simple assay procedure for 7-alkoxycoumarin O-dealkylase.

The in vitro biotransformation of 7-alkoxycoumarin by rat liver microsomes was studied to develop a simple and accurate assay procedure for 7-alkoxycoumarin O-dealkylase. 7-Alkoxycoumarin was converted to the O-dealkylated metabolite, 7-hydroxycoumarin, by aerobic incubation of the parent compound with microsomes and NADPH, but the decreased amount of 7-alkoxycoumarin in the reaction mixture was several times higher than that of the 7-hydroxycoumarin produced during the incubation. The thin-layer chromatogram of the ether extractable metabolites in the reaction mixture showed the existence of several fluorescent metabolites including 7-hydroxycoumarin. Fluorescent properties of the parent compound, 7-alkoxycoumarin, and most of the metabolites differed from that of 7-hydroxycoumarin, but the reaction cofactor, NADPH, showed similar properties. Treatment of the reaction mixture with perchloric acid resulted in conversion of NADPH to the non-fluorescent form without any effect upon the fluorescent properties of 7-hydroxycoumarin and its related compounds. Based on these properties, an improved and simple in vitro fluorometric assay of the O-dealkylation of 7-alkoxycoumarin was developed. The method is applicable to routine determination of O-dealkylase activity in both isolated microsomes and whole homogenate. Species differences in the substrate specificity of the O-dealkylation reaction and in the responsiveness of animals to the inducer were observed even with use of the liver homogenate obtained from untreated and phenobarbital- or beta-naphthoflavone-pretreated animals, similar to what was observed with the microsomal system.

7-Alkoxycoumarin O-Dealkylase↗
PubMed2001

Determination of D-sorbitol in human erythrocytes by an enzymatic fluorometric method with an improved deproteinization procedure.

We developed an improved enzymatic assay of D-sorbitol in human erythrocytes by employing highly specific D-sorbitol dehydrogenase from Pseudomonas sp. (EC 1.1.1.14) and replacing perchloric acid (HClO4) and potassium carbonate (K2CO3), generally used for deproteinization, with sodium hydroxide (NaOH) and zinc sulphate (ZnSO4). In this assay, erythrocytes were separated from plasma by centrifugation and washed once with physiological saline. Subsequently, the erythrocytes were lysed with distilled water and proteins precipitated with NaOH and ZnSO4. After centrifugation, the resulting colourless supernatant was mixed with a glycine buffer (pH 9.0) containing NAD+ and D-sorbitol dehydrogenase. After incubation for 30 min at 37 degrees C, the NADH produced was measured fluorimetrically. The fluorescence intensities were corrected for sample blanks, and the values of D-sorbitol were normalized for haemoglobin content. The method had an analytical range of 1-180 micromol/L. The intra- and inter-assay precisions were < 3.3% and < 5.8%, respectively. The detection limit was 0.65 micromol/L. In terms of the linearity, precision and sensitivity, the improved method using NaOH and ZnSO4 was superior to the conventional method using HClO4 and K2CO3.

Blood Chemical Analysis↗
PubMed1995

Molecular characteristics of porcine thymus histone H1 variants.

We constructed an assay system to measure the annealing activity that is one of the functional features of nuclear proteins, using ssDNAs derived from M13 phage recombinants which contained a complementary 406-bp portion each. Histone H1 variants were purified from porcine thymus by separation of chromatin, extraction with 5% perchloric acid, and reversed-phase HPLC. Three types of histone H1 variants were found by analysis of amino acid composition and on SDS-PAGE. All of these could promote the annealing. According to Hill's analysis all had similar numbers of binding sites to DNA strands but dissociation constants and annealing activity were different. The number of binding sites, dissociation constants, and annealing activity were changed by dephosphorylation of histone H1 variants. This result suggests that histone H1 variants have different affinities for DNA molecules and ssDNA-annealing activity, which is regulated by phosphorylation.

Amino Acids↗
PubMed1992

Simultaneous determination of tetrahydrofolate and N5-methyltetrahydrofolate in pig plasma by high-performance liquid chromatography with electrochemical detection.

An analytical method for measurement of tetrahydrofolate (THF) and N5-methyltetrahydrofolate (5MF) in pig plasma by the high performance liquid chromatography and electrochemical detection is described. The plasma sample was deproteinized by perchloric acid and the supernatant was analyzed using the following conditions; (a) phenyl bonded phase column as an analytical column; (b) mobile phase consisting of 20 mM acetate buffer (pH 3.6) containing 0.1 mM EDTA and acetonitrile (96.5:3.5, v/v); (c) an applied potential of +300 mV. Under the above condition, both peaks of THF and 5MF in the plasma were well separated. The detection limits of THF and 5MF were 0.15 and 0.13 ng/ml, respectively, at S/N = 3. The recoveries of THF and 5MF from the plasma spiked with standard THF and 5MF were 77.6 +/- 2.1% and 83.0 +/- 1.7% (mean +/- S.D.), respectively.

Animals↗