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Biomedical subjects

M Sugimura

Publications and source records attributed to M Sugimura.

At least 37 records · Page 2Linked to original sources
PubMed1991

Carcinogenic activity of endogenously synthesized N-nitrosobis(2-hydroxypropyl)amine in rats.

The carcinogenic activity of endogenously synthesized N-nitroso-bis(2-hydroxy-propyl)amine (NDHPA) was investigated in male Wistar rats administered bis(2-hydroxypropyl)amine (DHPA), mixed into a powdered diet at a concentration of 1%, and NaNO2 dissolved in distilled water at concentrations of 0.15% and 0.3%, for 94 weeks. Urinary excretion of NDHPA clearly demonstrated its endogenous synthesis in rats given 1% DHPA and 0.3% NaNO2, but not in the groups receiving either of these precursors alone. Tumours of the nasal cavity, lung, oesophagus, liver and urinary bladder were found in rats treated with 1% DHPA and 0.15% or 0.3% NaNO2. The incidences of nasal cavity and lung tumours reached 74% and 58% respectively, in rats given 1% DHPA and 0.3% NaNO2. The tumour distribution was almost the same as that seen in rats given NDHPA. These results indicate that endogenously synthesized NDHPA has similar carcinogenic activity to exogenously administered NDHPA in rats.

Animals↗
PubMed1991

Intracellular production of adrenal renin in the fetal mouse. An immuno-electron microscopical study.

Renin-containing cells in fetal adrenal glands of the mouse were investigated with the protein A-gold immunocytochemical technique. On Day 14 of gestation, a small number of specific granules were weakly immunoreactive and were distributed in the Golgi region. Sometimes, apparent exocytosis of gold-labelled particles could be seen opening into the extracellular space. On Day 16 of gestation, numerous gold particles were demonstrated in the Golgi region as well as in the specific secretory granules. Immunoreactivity of the specific granules was increased as compared with Day 14, though some granules were observed to have no reaction with the antibody. On Day 18 of gestation reactivity for renin decreased, while a few clustered immunoreactive granules were demonstrated just beneath the cell membrane. No gold particles were observed in the Golgi apparatus during this period and more granules negative for renin were noted than on Day 16 of gestation. These results suggest that renin is produced and released temporarily by adrenal cortical cells in the late fetal life of the mouse.

Adrenal Glands↗
PubMed1990

Interspecies differences in the population of multiple glutamate receptors expressed in Xenopus oocytes after injection of guinea pig, mouse and rat forebrain mRNAs.

Expression of multiple glutamatergic responses was compared in Xenopus oocytes several days after injection of poly(A)+ RNAs from guinea pig, mouse and rat forebrains. No difference either in the characteristics of each response or in the amplitude of N-methyl-D-aspartate response was observed between the oocytes injected with mRNA from different species. However, the average magnitudes of kainate (KA) and oscillatory quisqualate (QA) responses produced by guinea pig brain mRNA were 1/2 and 1/6 times, respectively, of those by rat brain mRNA. These results may reflect that the guinea pig forebrain contains smaller amounts of ionotropic KA and metabotropic QA receptors than the rat forebrain.

Animals↗
PubMed1990

Renin immunohistochemistry in the adrenal gland of the mouse fetus and neonate.

The development of renin-containing cells in fetal and neonatal adrenal glands of the mouse was studied using immunohistochemistry. On days 13-14 of gestation, immunoreactivity for renin was first observed in a few cortical cells of the gland, appearing as small patchy or granular reaction products in the perikaryon. The mitotic configurations of the cells demonstrating immunoreactivity were noted. On day 16 of gestation, a number of intensively immunoreactive cells were distributed in the aortal side of the cortical zone. On day 18 of gestation, and day 1 postparturition, a small number of potent immunoreactive cells were still found in the cortical area. Immunoreactivity of the cytoplasm was observed in the cells, some showing an intensive reaction and others possessing numerous tiny granules just below the cell membrane. On days 3, 5, and 7 after birth, no renin-containing cells were found in the adrenal gland. The ratio of the numbers of renin-positive cells in certain areas to the numbers in the entire cortical area was significantly increased on day 16 of gestation, but there was no sexual difference in the ratios. The ratios were decreased subsequently until day 1 after birth. The possible significance of renin synthesis in specific adrenal cells in fetal life is discussed with respect to an important involvement of angiotensin II in the morphogenesis of the adrenal gland of the mouse.

Adrenal Glands↗
PubMed1990

Different drug-susceptibilities of long-term potentiation in three input systems to the CA3 region of the guinea pig hippocampus in vitro.

The susceptibilities to several drugs of long-term potentiations in the three input systems (mossy, commissural/associational and fimbrial fibres) to CA3 pyramidal neurones were investigated in hippocampal slices from the guinea pig. D-2-Amino-5-phosphonovalerate (D-APV), a selective antagonist at N-methyl-D-aspartate (NMDA) receptors, blocked the long-term potentiations in the commissural/associational fibre- and fimbrial fibre-CA3 systems, but did not significantly affect that in the mossy fibre-CA3 system. The latter was suppressed by kynurenate, a non-selective glutamate receptor antagonist. On the other hand, naloxone, an opioid antagonist, inhibited and bifemelane, which improves metabolism in brain and has an anti-amnesic action, augmented long-term potentiation in mossy fibre-CA3 system but did not influence those in commissural/associational fibre- and fimbrial fibre-CA3 systems. These findings suggest that the mechanisms, relevant to production of long-term potentiation in the mossy fibre-CA3 system, are different from those in the commissural/associational fibre- and fimbrial fibre-CA3 systems. N-Methyl-D-aspartate receptors are involved in the latter systems, while non-NMDA receptors for L-glutamate and opioid receptors are involved in the former. Further, the mossy fibre-CA3 system is more susceptible to a drug, having an anti-amnesic action, than are the other two systems.

2-Amino-5-phosphonovalerate↗
PubMed1990

Dose-response study of N-nitrosomethyl(2-hydroxypropyl)amine-induced nasal cavity carcinogenesis in rats.

Dose response to the carcinogenic activity of N-nitrosomethyl(2-hydroxypropyl)amine (MHP) was investigated for the nasal cavity of male Wistar rats. MHP dissolved in 0.9% saline was administered intraperitoneally once a week for 12 weeks at doses of 0, 4.4, 8.8 and 17.6 mg/kg body weight, and all surviving animals were sacrificed 26 weeks after the beginning of the experiment. Hyperplasias, papillomas and squamous cell carcinomas were induced. Hyperplasias could be divided into flat, protruding and downgrowth types and were observed in respiratory and squamous epithelial regions. Papillomas and squamous cell carcinomas developed in the respiratory region, and the incidence of the latter reached 83% in rats which received the highest dose of MHP. These results indicate that MHP shows its carcinogenic activity of the nasal cavity by the development of squamous cell carcinomas.

Animals↗
PubMed1990

A comparative study on S-100 protein-immunoreactive cells in lymph nodes.

S-100 protein-immunoreactive cells of the lymph node were examined in the duck and 9 mammalian species, such as guinea pigs, dogs, cats, horses, pigs, goats, cows, Japanese serows and crab-eating monkeys. S-100 protein was detected in follicular dendritic cells (FDC) and tangible-body macrophages (TBM), sinus and parenchymal macrophage (MP), sinus endothelial cells (SEC) and interdigitating reticulum-like cells (IRC) in the node of mammalian species, but not in the duck except nervous elements. S-100-positive FDC and TBM were detected in germinal centers of the nodes in all mammalian species, but immunoreactivity of the other 3 cell types varied according to animal species and individuals of the same species. S-100 alpha subunit was detected in FDC, with the exception of those of the duck and guinea pig. The subunit was also detected in SEC of the dog, cow and Japanese serow. In the guinea pig, a unique S-100 alpha-positive giant dendritic cell (GDC) was found in the subsinusal cortical area. In addition, S-100 immunoreactive lymphocytes were observed in the paracortex-equivalent area of pig nodes. Arterial endothelial cells of the pig and cow were immunoreactive to S-100 beta subunit.

Animals↗
PubMed1990

Localization of immunoglobulins in the chicken oviduct.

Studies were made on the distribution of lymphoid tissues and immunoglobulin (Ig: IgA, IgG and IgM)-containing cells (cIg: cIgA, cIgG and cIgM) and the localization of immunoglobulins (Igs) in the oviducal walls of laying hens. Lymphocyte accumulations were occasionally observed, located mainly in the middle infundibulum and in the regions from the isthmus to the vagina. The number of cIgG significantly predominated over that of cIgA or cIgM in the mucosal connective tissue of the magnum and the isthmus. In contrast, in the regions other than the magnum and the isthmus, these three types of cIg were fewer in number. Igs were localized in some superficial epithelial cells (SECs) and glandular cells (GlCs) of the oviduct. Many IgG-containing SECs were found in the infundibulum, the isthmus, and the cranial and major uterus. IgA- or IgM-containing SECs were rare throughout the oviduct. Three types of Ig-containing GlCs were numerously found in the magnum, though lymphocyte accumulations were scarce there. In the isthmus, many IgG-containing GlCs were found, while IgA- or IgM-containing GlCs were rarely observed. Ig-containing GlCs in the magnum were considerably decreased in number after the egg passage. The results suggest that the maternal Igs are transferred to the egg mainly through GlCs in the magnum of the chicken oviduct, and that the oviducal lymphoid tissues have little relationship to the passive immunity.

Animals↗
PubMed1990

Dynamic microstructure of plasma and mitochondrial membranes from bullfrog myocardium--a nanosecond time-resolved fluorometric study.

The viscosity of the phospholipid bilayer and the wobbling angle of the phospholipid molecules of mitochondrial membranes and plasma membranes from bullfrog myocardium were measured with a nanosecond time-resolved fluorometer using pulsed excitation of a hydrophobic fluorescent probe, 1,6-diphenyl-1,3,5-hexatriene (DPH). The mean +/- S.D. in the viscosity of the mitochondrial and plasma membranes was 0.54 +/- 0.9 and 0.37 +/- 0.03 P, respectively, at 30 degrees C. The wobbling angle of phospholipid molecules was 42 +/- 1 and 47 +/- 1 degree, respectively. Cholesterol content was lower in mitochondria (6.4 micrograms/mg protein) than in plasma membranes (43.7 micrograms/mg protein) but phosphatidylethanolamine concentration was higher in mitochondria (31.8%) than in plasma membranes (27.3%). Cardiolipin was contained only in mitochondria. The results of these lipid analyses appear consistent with the measurements of membrane viscosity and phospholipid wobbling angle. When the results are compared with those from a previous study on the erythrocyte membranes from bullfrogs, viscosity is found to increase in the order mitochondrial membranes less than plasma membranes less than erythrocyte membranes. The complex requirements of biomembranes of organelles performing different functions appear to be met by the particular dynamic microstructure of the biomembrane. The effect of membrane viscosity on oxygen diffusion through membranes is discussed.

Adenosine Triphosphatases↗
PubMed1990

New type metal bracket for suppression of resin remaining in debonding.

A new type of metal bracket was prepared to minimize the destruction at the bracket-resin interface and to suppress resin from remaining on the tooth surface in debonding. The brackets were made of stainless steel and had a modified cylindrical outward shape (phi 3.8 mm x 1.8 mm), twin-type wings, and a 0.018 inch (0.457 mm) slot. Retentive forces and debonding aspects of residual resin for the brackets were studied using three representative adhesives. The mean tensile strengths at the bracket-resin interface were over 80 kgf/cm2 for all three resins. As the quantitative evaluation for the residual resin condition, a resin remaining ratio (RRR) was adopted. The aspects of the residual resin differed according to the type of adhesive resin used. Almost no resin was detected on the tooth surface just below the central part of the bracket, and even for the peripheral part which did not have an effective resin retention form, the RRR was under 30% for the heavily filled resin.

Acrylic Resins↗
PubMed1990

A new type ceramic bracket for suppression of resin remaining in debonding.

A new type of ceramic bracket was prepared to minimize the destruction at the bracket-resin interface and to suppress resin remaining on the tooth surface in debonding. The brackets were of a chemical bonding type, and had a box-formed cavity in the bracket base to hold resin, a 0.018 inch slot, and twin-type wings. Impact strengths and debonding aspects of the residual resin were studied. The impact strengths of the brackets seemed to exceed the desired level, compared to other control ceramic brackets or metal brackets. A resin remaining ratio (RRR) was adopted as the quantitative evaluation for the residual resin condition. Mean RRR's of the brackets were about 10%, which was a very low value in comparison to the other brackets.

Ceramics↗
PubMed1990

Extension of the jaw opening reflex and effects of a central muscle relaxant (afloqualone) in the rat.

How widely the jaw opening reflex (JOR) extends was examined in the rat. Recording was done in the anterior (AD) and posterior (PD) digastric, sternohyoid (SH) and sternomastoid (SCM) muscles. Electric stimulation was given to the mandibular incisor pulp. Evoked electromyogram (EMG) activities could be recorded in each muscle. The thresholds for JOR increased from AD to SCM. Intravenously administered afloqualone, a centrally acting muscle relaxant, inhibited both JOR and its parallels promptly and dose-dependently. The possible clinical significance in temporomandibular joint dysfunction will be discussed.

Animals↗
PubMed1989

Extracellular matrix of the superior olivary nuclei in the dog.

The extracellular matrix around nerve cell bodies in canine lateral and medial superior olivary nuclei was examined by conventional electron microscopy, Golgi impregnation and histochemical techniques. Each neuron is surrounded by a region of myelin-free neuropil embedded amongst the myelinated fibres of the trapezoid body. In the myelin-free neuropil there are astrocytes, axons, synaptic boutons and extracellular matrix. The extracellular matrix fills the spaces between slender axons near the terminals, synaptic boutons and glial processes, but not the synaptic cleft. Golgi impregnation selectively stains the perineuronal nets which cover some of all of the nerve cell bodies and dendrites. The Golgi-EM method revealed that the impregnated profiles of the nets are restricted to the extracellular matrix. Synaptic boutons are situated in the holes of the perineuronal nets. Peanut (PNA) and soybean (SBA) agglutinins bound the extracellular matrix but not the synaptic boutons, glial processes, nerve cell bodies or basal lamina of blood capillaries. Light microscopic immunohistochemistry of the glial fibrillary acidic protein (GFAP) and S-100 protein did not stain a layer corresponding to the extracellular matrix and synapses but showed an intensely positive reaction immediately outside this layer. These data suggest the existence of a unique microenvironments associated with glycoconjugates around nerve cell bodies in canine superior olivary nuclei.

Animals↗
PubMed1989

Idebenone and vinpocetine augment long-term potentiation in hippocampal slices in the guinea pig.

The effects of idebenone and vinpocetine which reportedly prevent impairment of learning and memory were studied in vitro, on the long-term potentiation of the population spike in the pyramidal layer of CA3 region of slices of hippocampus in the guinea pig. Idebenone (10(-9) M-10(-6) M) or vinpocetine (10(-7) M-10(-6) M) significantly augmented long-term potentiation in the mossy fibre-CA3 pyramidal cell system, without any significant changes in population spikes in the absence of tetanic stimulation. These results suggest that both drugs have direct actions on the hippocampal neurones to augment long-term potentiation at fairly small concentrations. Further, when the two drugs were applied together, the augmenting effects were additive.

2-Amino-5-phosphonovalerate↗
PubMed1989

Indeloxazine augments long-term potentiation in the mossy fiber-CA3 system of guinea pig hippocampal slices.

The effects of indeloxazine and piracetam, which reportedly prevent experimental impairments of memory and learning, on long-term potentiation (LTP) of the population spike in the mossy fiber-CA3 system were studied in vitro using the guinea pig hippocampal slices. Indeloxazine (10(-6) M) or piracetam (10(-4) M) significantly augmented the LTP and the effect of indeloxazine on the LTP was approximately 100 times as potent as that of piracetam.

Animals↗
PubMed1989

Studies on sustained-release suppositories. II. Evaluation of polymer electrolyte containing acidic groups for prolonged rectal absorption of bacampicillin in rabbits.

Rectal absorption of bacampicillin hydrochloride (BAPC) was found to show the best bioavailability with Witepsol H-15 as suppository base among various Witepsol bases. However, an effective plasma concentration of drug (above 0.5 micrograms/ml) was only maintained for 2 h, so sustained-release suppositories of BAPC were studied. Bacampicillin reacts with acidic polymer electrolytes such as pectic acid (Pc), chondroitin sulfate (Cd) and precipitates as its adduct with the polymer in an aqueous solution. The dissolution rate of BAPC from the adducts in a solution was slower than that of BAPC itself. The absorptions of BAPC from the suppositories containing the adducts were prolonged, but the bioavailabilities were decreased compared to that from the suppository containing BAPC alone. Similar prolonged absorption could be obtained simply by mixing Pc or Cd with BAPC in a base. Further, the absorption rate was found to be controlled by the amount of the polymer addition, and both a high plasma level and excellent bioavailability were obtained. This desirable outcome may be due to the simultaneous occurrence of rapid absorption of BAPC itself and formation of the adducts.

Ampicillin↗
PubMed1989

Morphology of blood cells in carp (Cyprinus carpio L.).

The morphology of blood cells in the carp was investigated by light and electron microscopy. Erythrocytes, thrombocytes, lymphocytes, granulocytes and monocytes were identified as the peripheral blood cells. Thrombocytes were round to long oval, each containing vesicular and microtubular structures and an oval nucleus with abundant heterochromatins. Lymphocytes were divided into three types in size, small, medium and large. Some of the small and medium lymphocytes were alpha-naphthyl-acetate esterase (ANAE) positive, while large lymphocytes were pyroninophilic. Granulocytes were distinguished into three types (type I, type II and type III) according to the morphology of the nucleus and granules. Type I granulocytes possessed lobulated nuclei and a large number of cytoplasmic granules, each of which was oval and contained electron-dense materials and a crystalloid. Type II granulocytes had small eccentric nuclei and were subdivided into IIa and IIb granulocytes by electron microscopic analysis. Granules of type IIa granulocytes were furnished with an electron-dense rim. Granules of type IIb granulocytes were larger than those of type IIa, containing randomly distributed electron-dense and electron-lucent materials. Type III granulocytes possessed round nuclei and a few large granules. The granules were filled with regularly arranged fibriform materials and some needle-like structures. Monocytes were morphologically similar to those of mammals.

Animals↗