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Biomedical subjects

T Noguchi

Publications and source records attributed to T Noguchi.

At least 847 records · Page 47Linked to original sources
PubMed1986

Effects of dietary nutrients on lipogenic enzyme and mRNA activities in rat liver during induction.

By feeding a carbohydrate diet (without protein) to fasted rats, malic enzyme mRNA activity in the liver was increased to the level in rats fed a carbohydrate and protein diet, whereas the enzyme activity itself was increased to 60% of that level. It appears that malic enzyme mRNA activity was increased by dietary carbohydrate, while dietary protein contributed to an increase in the translation of mRNA. In the animals fed carbohydrate without protein, glucose-6-phosphate dehydrogenase mRNA activity increased to 50% of the level in rats fed the carbohydrate and protein diet, whereas the enzyme activity increased to only 25%. By feeding a protein diet (without carbohydrate), glucose-6-phosphate dehydrogenase activity increased to 65% of the level in rats fed both carbohydrate and protein. This enzyme induction appears to be more dependent on protein than carbohydrate. With the carbohydrate diet, acetyl-CoA carboxylase was induced up to the level in the carbohydrate and protein diet group, whereas fatty acid synthetase was induced to only 33%. Acetyl-CoA carboxylase induction appears to be carbohydrate dependent. On the other hand, isotopic leucine incorporation studies showed that the magnitudes of the enzyme inductions caused by the dietary nutrients should be ascribed to the enzyme synthesis rates rather than the degradation. By fat feeding, the mRNA activities of malic enzyme and glucose-6-phosphate dehydrogenase were markedly decreased along with the enzyme induction. Fat appears to reduce these enzyme inductions before the translation of mRNA.

Acetyl-CoA Carboxylase↗
PubMed1986

Ureidoglycollate lyase, a new metalloenzyme of peroxisomal urate degradation in marine fish liver.

Ureidoglycollate lyase (UGL, EC 4.3.2.3), which catalyses the degradation of S(-)-ureidoglycollate to urea and glyoxylate, was found in the peroxisomes of marine fish (sardine and mackerel) liver. The enzyme highly purified from sardine liver had an Mr of about 121,000, with two identical subunits. When UGL was purified in the presence of 1 mM-EDTA, a much less active form was obtained. It was markedly activated by bivalent metal ions, particularly by Mn2+. The Mn2+-activated enzyme remained active when free Mn2+ was removed by gel filtration on Sephadex G-50, suggesting that UGL may be a metalloenzyme and the activation resulted from the binding of Mn2+ to the apoenzyme. UGL was found to be essential in peroxisomal urate degradation, since allantoate, the intermediate of urate catabolism, was found to be degraded to urea and glyoxylate in a two-step reaction catalysed by allantoicase (EC 3.5.1.5) and UGL via S(-)-ureidoglycollate as an intermediate in fish liver peroxisomes, but not in a one-step reaction as previously believed.

Amidine-Lyases↗
PubMed1986

Studies of the influence of chloro-substituent sites and conformational energy in polychlorinated biphenyls on uroporphyrin formation in chick-embryo liver cell cultures.

Treatment of cultured chick-embryo liver cells with polychlorinated biphenyls (PCB) results in decreased uroporphyrinogen decarboxylase activity and increased uroporphyrin accumulation. In the present study we examined the effect of the chloro- or bromo-substituent sites in biphenyls (BP) on uroporphyrin accumulation in cultured hepatocytes and the three-dimensional structure of these congeners determined by molecular orbital calculations using a MNDO ('modified neglect of diatomic overlap') method. Among 20 congeners examined, those which were effective in stimulating porphyrin accumulation contained at least two Cl or Br atoms at the lateral adjacent positions in each phenyl ring, e.g. 3,4,3',4'-tetrachloro-, 2,4,3',4'-tetrachloro-, 3,4,5,3',4',5'-hexachloro- and 3,4,5,3',4',5'-hexabromobiphenyl, whereas those which contained less than two halogen atoms or more than three halogen atoms in each phenyl ring or those which contained halogen atoms at 2,2'-positions were not effective. On the basis of the conformational energy (delta E, difference from the most stable conformational energy), which is calculated as a function of the dihedral angle (theta) between the two phenyl rings, biphenyl congeners can be classified into four groups with different conformations. The conformation of active PCB was relatively flexible, whereas inactive species had a rigidly angulated conformation. Furthermore, the calculated probability of the conformation distribution for each congener indicated that the probability of co-planarity was higher for active biphenyls than for inactive congeners. These structural characteristics suggest the significance of both the chloro-substituent sites and the conformational energy reflecting the phenyl-ring twist angles in determining the inhibitory effect of PCB on uroporphyrinogen decarboxylase activity.

Animals↗
PubMed1986

Evolution of allantoinase and allantoicase involved in urate degradation in liver peroxisomes. A rapid purification of amphibian allantoinase and allantoicase complex, its subunit locations of the two enzymes, and its comparison with fish allantoinase and allantoicase.

Allantoinase and allantoicase are located in the same protein molecule in amphibian liver, whereas the two enzymes are different proteins in marine fish and invertebrate liver (Takada, Y., and Noguchi, T. (1983) J. Biol. Chem. 258, 4762-4764). The amphibian enzyme was rapidly purified from frog liver by using its following characteristics. 1) The enzyme binds to the intracellular membranes in the hypotonic solution. 2) The membrane-bound enzyme is not solubilized by the detergent. 3) The membrane-bound enzyme is solubilized by oxaloacetate. The electrophoresis of the purified enzyme gave a single protein band in the absence of sodium dodecyl sulfate, and gave two protein bands with molecular weights of 48,000 and 54,000, respectively, in the presence of sodium dodecyl sulfate. With a specific antibody raised against each subunit, allantoinase activity was found to be from the large subunit, and allantoicase activity to be from the small subunit. This amphibian allantoinase and allantoicase complex was compared with allantoinase and allantoicase purified from fish liver. Fish allantoinase was a single peptide and fish allantoicase was composed of two identical subunits. Fish allantoinase had an identical molecular weight with amphibian large (allantoinase) subunit and the subunit of fish allantoicase with amphibian small (allantoicase) subunit. These results suggest that the evolution of fish to amphibian resulted in the dissociation of allantoicase into subunits and in the association of allantoinase with allantoicase. The two enzymes are lost by further evolution.

Amidohydrolases↗
PubMed1986

Complete amino acid sequence of rat L-type pyruvate kinase deduced from the cDNA sequence.

cDNA clones, containing the entire coding region of rat L-type pyruvate kinase, were isolated and their nucleotide sequences were determined by the dideoxy-chain-termination method. The predicted coding region, which spans 543 amino acids, established the complete amino acid sequence of the L-type isozyme of pyruvate kinase for the first time. The deduced amino acid sequence of the L type has one phosphorylation site in its amino terminus and shows about 68% and 48% homologies with M1-type pyruvate kinase of chicken and yeast pyruvate kinase respectively. Domain A exhibits higher homology than domains B and C. The residues in the active site of the L-type enzyme of rats, lying between domains B and A2, are rather different from those of the M1-type enzyme of chickens, but other residues constituting the active site are identical with those of the chicken M1 type except for one amino acid substitution.

Amino Acid Sequence↗
PubMed1986

Occurrence of tetrodotoxin in the flatworm Planocera multitentaculata.

The paralytic toxin which occurs in a flatworm Planocera multitentaculata was partially purified by column chromatography using Bio-Gel P-2 and Bio-Rex 70 (H+ form). Thin-layer chromatographic, electrophoretic and gas chromatography-mass spectrometric analyses demonstrated that the flatworm toxin is tetrodotoxin.

Animals↗
PubMed1986

Local differences in toxin composition of a xanthid crab Atergatis floridus inhabiting Ishigaki Island, Okinawa.

Specimens of a xanthid crab Atergatis floridus were collected from two adjacent areas in Kabira Bay, Ishigaki Island, Okinawa and compared with respect to toxicity and toxin composition. 'Reef specimens', which were collected from the reefs of Kabira Bay, showed an average toxicity score of 380 MU/g as paralytic shellfish poison, and a toxin composition consisting mainly of saxitoxin and a neosaxitoxin-related substance. On the other hand, 'Kojima specimens', which were collected from a small island in the bay, showed an average toxicity of 38 MU/g as tetrodotoxin, and a toxin composition consisting mainly of tetrodotoxin and related substance(s).

Animals↗
PubMed1986

Retarded growth of the suprachiasmatic nucleus and pineal body in dw and lit dwarf mice.

The suprachiasmatic nucleus (SCN) and the pineal body in 3 types of inherited hormone-deficient mice, the dw, lit and hyt mice were examined by morphological, morphometric and biochemical techniques. In the dw and lit mice the SCN was underdeveloped. In the ventral part of the SCN, where most of the retinal fibers appeared to terminate, both cell number and cell size were decreased, although the size of the SCN was unaltered. In addition, the pineal bodies of both mice were morphologically underdeveloped and showed low levels of N-acetyltransferase activity. In contrast, the hyt SCN was comparable to the normal controls in every respect. The hyt pineal was well developed and showed levels of enzyme activity comparable to the controls. However, in all the deficient mice, the optic nerve appeared to be normal in morphological and biochemical studies. These results suggest that the underdevelopment of the pineal body, the reduced levels of spontaneous locomotion and the indistinct diurnal periodicity of the dw and lit mice might be related to the retarded neuronal growth of the SCN, and that growth hormone likely is indispensable for the development of the SCN.

Animals↗
PubMed1986

Cloning and expression of a chloramphenicol acetyltransferase gene in cytosine-substituted T4 bacteriophage.

We have developed an efficient method for transferring foreign genes into the T4 phage genome. Any foreign genes inserted into the T4 uvsY gene cloned on plasmids can be transferred into a cytosine-substituted T4dC(delta NB5060) phage genome by a replacement type of recombination. To achieve this, we constructed chimeric plasmids which had a chloramphenicol acetyltransferase gene (cat) derived from transposon Tn9 inserted into the Bg/II site within the T4 uvsY gene on pBR322. The cat gene was then transferred by in vivo recombination into the T4dC(delta NB5060) phage genome. Moreover, it was demonstrated that the cat gene in the hybrid T4dC phage was expressed upon phage infection and development.

Acetyltransferases↗
PubMed1986

Bronchial artery aneurysm.

Two patients with bronchial artery aneurysm were surgically treated. One patient had a saccular aneurysm in the root of the left bronchial artery, and the other had a mediastinal as well as an intrapulmonary aneurysm, rupture of the latter of which had resulted in massive hemoptysis. Twelve reports of bronchial artery aneurysm have appeared in the literature to date. Those of mediastinal location frequently have symptoms mimicking dissecting aortic aneurysm, whereas their intrapulmonary counterparts usually are manifested by hemoptysis. Although its etiological process remains to be elucidated, this rare entity should be recognized in the clinical practice.

Adolescent↗
PubMed1986

Occurrence of tetrodotoxin and anhydrotetrodotoxin in Vibrio sp. isolated from the intestines of a xanthid crab, Atergatis floridus.

Vibrio sp. isolated from a xanthid crab, Atergatis floridus, was cultured, and tetrodotoxin (TTX) and anhydroTTX were indicated to be present in several fractions of the cell extract and the culture medium by reverse phase HPLC. The presence of the C9-base in alkaline hydrolyzates of these fractions was confirmed by GC-MS and UV spectrometry. These results showed the production of TTX and anhydroTTX in the Vibrio sp., thus indicating one of the origins of TTX in nature.

Animals↗
PubMed1986

Spermatogenesis in Snell dwarf, little and congenitally hypothyroid mice.

The status of spermatogenesis in Snell dwarf, little and congenitally hypothyroid mice was studied. In all of these mice with a hormone deficiency the seminiferous tubules were smaller in size and contained fewer spermatogonia, spermatocytes, spermatids and spermatozoa than did those of normal control mice. There was no substantial difference in the Johnsen score between the hormone-deficient mice and normal control mice, but the former had underdeveloped seminiferous tubules with a corresponding paucity of germ cells, which may be partly responsible for the infertility of these mice. In the present study, growth hormone and thyroxine were administered separately to growth hormone-deficient and thyroxine-deficient mice, respectively. Such replacement therapy brought about an increase in cell counts of the seminiferous tubules and in sperm counts in both groups.

Animals↗
PubMed1986

Stimulatory effects of growth hormone and thyroxine on the concentration of gangliosides in the Snell dwarf cerebrum.

The concentration of gangliosides in the Snell dwarf mouse cerebrum was monitored from postnatal day 5 to day 40. In the dwarf cerebrum, the concentration of total gangliosides increased up to postnatal day 20 and then stopped, whereas in the control cerebrum, it continued to increase up to postnatal day 40. At postnatal day 40, the ganglioside level in the dwarf cerebrum was 70% of that in the control cerebrum. Among the ganglioside species, the concentrations of GM4, GM2, GM1, GD1a, GD3, GD1b, GT1b, and GQ1b were significantly lower in the dwarf cerebrum than in the controls at postnatal day 40. The reduced concentrations of ganglioside species GM2, GD1a, GD3, GD1b, and GQ1b were completely restored by administration of bovine growth hormone (GH) during the first 20 days of postnatal life. The reduced concentration of the GM1 and GM4 species were most efficiently restored by administration of bovine GH plus thyroxine (T4) during the second 20 days of postnatal life. These results indicate that the lower ganglioside concentrations in the dwarf cerebrum can be elevated by hormone therapy and that there exist distinct GH and T4 actions on the enzymes participating in ganglioside metabolism.

Animals↗
PubMed1986

Structure of dictyosomes in Scenedesmus acuminatus observed by the freeze-substitution method.

The ultrastructure of dictyosomes in Scenedesmus acuminatus was studied by the freeze-substitution method. The cisternal membranes of dictyosomes clearly exhibited three-layered structures. Electron-dense particles were visible on or in the proximal cisternal membranes. The upper and lower membranes of the distal cisternae were in close contact with each other at the cisternal centre. The electron density of transfer vesicles, secretory vesicles and cisternal margins was very high. These findings differ considerably from those obtained by conventional chemical fixation, and suggest that freeze-substitution is superior to chemical fixation for preserving structures, without distortion and preventing dissolution of constituent substances.

Chlorophyta↗