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Biomedical subjects

M Shimada

Publications and source records attributed to M Shimada.

At least 829 records · Page 46Linked to original sources
PubMed1983

Synaptic changes in Purkinje cell dentritic spine of mouse cerebellum after neonatal administration of cytosine arabinoside.

This study was undertaken to elucidate morphological changes in the synaptic area of the Purkinje cell dendritic spines when granule cells were decreased in number. The mice were injected s.c. with 30 mg/kg b.w. of cytosine arabinoside on days 2, 3, and 4, and on days 7, 8 and 9, and were designated as group I and group II, respectively. The mice injected with saline on days 2, 3, and 4 served as control. The cerebella of the mice in each group were examined by electron microscopy on days 30, 60, and 90. Using photographs thus obtained, the synaptic length and area of Purkinje cell dendritic spines which participated in synapses with axons of granule cells were measured by computer. In the controls, these spines did not increase significantly either in synaptic length or in spine area in the duration from 30 to 90 days after birth. In the 90-day-old mice belonging to group I and group II, however, they increased by about 20% in the synaptic length and by about 35% in the spine area as compared to those in age-matched control. The elongation and enlargement show that the synaptic surface on the spine spreads to compensate for synapses lost by reduction in number of granule cells in experimental groups.

Age Factors↗
PubMed1983

Ultrastructural study on nervous system of fetus with GM1-gangliosidosis type 1.

The nervous system of a 22-year-old fetus with GM1-gangliosidosis type 1 was studied by electron microscopy. The tissues thus examined were the cerebral cortex at the parietal region, the cerebellum, the thoracic spinal cord, the Auerbach's myenteric plexus in the large intestine and the radial nerve fibers. In the cerebral cortex, membrane-bound vacuoles, which occasionally contained stacks of fine fibrils, were observed in the large young neurons in the deeper part of the cortical plate. The neurons in the other part of the cerebral cortex carried no storage materials. In the cerebellum, the membrane-bound vacuoles with stacks of fine fibrils were seen only in the Purkinje cells. The neurons in the spinal cord also contained several zebra-like bodies and the above membrane-bound vacuoles. As for the peripheral nervous system (PNS), neurons in the Auerbach's myenteric plexus carried membranous cytoplasmic bodies and zebra-like bodies. Some of the axons in the radial nerve fibers also contained a lot of pleomorphic electron-dense bodies and a few membranous cytoplasmic ones. These results show that the accumulation of storage materials is started in the large neurons which are produced in the early stage of neurogenesis in the central nervous system (CNS). Additionally, the observed membrane-bound vacuoles are considered to be structures which occur before the membranous cytoplasmic bodies and/or the zebra-like bodies. It is also elucidated that the PNS is affected earlier than the cerebral and cerebellar cortices and thoracic spinal cord.

Cerebellum↗
PubMed1983

Neonatal monosodium glutamate-induced lesions of hypothalamus increase intestinal fat absorption in adult mice.

The hypothalamic lesion induced by monosodium glutamate injection during the suckling period affected the absorption of fat from the intestine. Mice in group 1, in which the hypothalamic lesion included not only the arcuate nucleus, but also the basal preoptic area and two-thirds of the ventromedial nucleus, showed more efficient rates of fat absorption with high serum concentrations of immunoreactive insulin than the control. Mice in group 2, in which the hypothalamic lesion was confined mostly to the arcuate nucleus, also showed a significant increase in fat absorption, but elevated immunoreactive insulin was not found in the serum of these mice.

Aging↗
PubMed1983

Development of physical dependence on and tolerance to morphine in rats treated with morphine-admixed food.

1. The development process of physical dependence on and tolerance to morphine has been explored in rats treated with morphine-admixed food (0.5 mg/g of food) during 1 to 7 days. 2. In the morphine-treated animals, body weight loss was observed after the abrupt morphine withdrawal. 3. Intensity and time course of the weight loss were correlated to the morphine treatment. 4. On the other hand, the morphine-treated rats showed abnormal behaviors, such as diarrhea, ptosis, teeth chattering, salivation, body shakes, vocalization, nose bleed, irritability, aggression, lacrimation and writhing upon naloxone injection. 5. Loss of body weight, measured 3 hours after naloxone injection, was also correlated to the duration of morphine treatment. 6. Tolerance to the analgesic effect of morphine developed within one day in rats treated with morphine-admixed food. 7. The drug-admixed food ingestion method has the advantage of rapidly inducing a high degree of physical dependence and tolerance without causing morbidity or lethality in animals. It also eliminates the need for excessive handling of animals.

Animals↗
PubMed1983

Effects of excess amounts of synthetic amino acid preparations on hypothalamus of mice and kittens.

The relationship between the neurotoxicity caused by excess amounts of synthetic amino acid preparations and serum levels of a certain amino acid was examined using suckling mice and kittens. Three preparations, two of which contained aspartic acid and glutamic acid, were injected intraperitoneally into neonatal mice. Almost all the animals which were treated with the preparations containing aspartic acid and glutamic acid at a dosage of more than 40 microliters/g body weight (b.w.) showed hypothalamic lesions. The severity of these increased according to each dose increment. On the other hand, none of the animals treated with the preparation containing neither aspartic acid nor glutamic acid sustained hypothalamic lesions. All kittens injected intravenously with the preparation containing aspartic acid and glutamic acid at dosages of more than 20 microliters/g b.w. also showed hypothalamic lesions, but none of the kittens treated with dosages of less than 10 microliters/g b.w. did. Serum levels of each amino acid reached their highest values as early as 5 min after injection and then returned abruptly to the control value within 3 h.

Amino Acids↗
PubMed1983

Oral administration of prostaglandin E2 in the hypoplastic left heart syndrome.

Oral administration of prostaglandin E2 resulted in marked clinical and hemodynamic improvement in patients with hypoplastic left heart syndrome. A lessening of metabolic acidosis and an increase in blood pressure were evident. These results indicate that the ductus arteriosus was effectively dilated by oral prostaglandin E2 in patients with ductus-dependent systemic circulation, as in the case of ductus-dependent pulmonary circulation. Surgical risk will also be reduced by pretreatment with oral prostaglandin E2.

Administration, Oral↗
PubMed1983

Microsomal activation of 2-amino-3-methylimidazo[4,5-f]quinoline, a pyrolysate of sardine and beef extracts, to a mutagenic intermediate.

The mechanism involved in the metabolic activation of 2-amino-3-methylimidazo[4,5-f]quinoline, which is a pyrolysate isolated from broiled foods, to a mutagenic intermediate was studied in vitro. In a system containing hepatic microsomes and reduced nicotinamide adenine dinucleotide phosphate, 2-amino-3-methylimidazo[4,5-f]quinoline was converted to a product which was directly mutagenic to Salmonella typhimurium. The structure of the mutagenic metabolite was determined as the 2-N-hydroxy derivative on the basis of the chemical properties and the mass spectral evidence of the azoxy adduct with o-nitrosotoluene. The activation reaction was mediated by microsomal enzymes and was inhibited by carbon monoxide, 7,8-benzoflavone, and other chemicals which were known to inhibit the cytochrome P-450-dependent reaction. With the use of four forms of purified cytochrome P-450, the N-hydroxylation of 2-amino-3-methylimidazo[4,5-f]quinoline and the induction of the reverse mutation of the bacteria were clearly demonstrated to be catalyzed mainly by a high-spin form of cytochrome P-450, P-448 II-a.

Animals↗
PubMed1983

[Surgical treatment of total anomalous pulmonary venous connection].

Surgical experience of 70 patients with TAPVC between 1966 and 1982 were reviewed. Their age ranged from 2 days to 13 years. Fifty-two patients (74%) were below 6 months of age, 36 (51) below 3 months and 17 (24%) were neonates, respectively. Thirty-seven patients (56%) were with supracardiac type, 14 (20%) were with cardiac type and 12 (17%) were with intracardiac type. Results of operation below 6 months of age were unsatisfactory. Only 10 patients including 3 neonates out of 52 survived. However, 16 of 18 patients over 6 months of age survived. Early referral and emergency intracardiac repair is important in small babies as well as precise operation and fine bypass technique. Patients with supersystemic pulmonary hypertension immediately after surgery showed poor prognosis. Long-term results with 26 survivors were satisfactory. Eighty-one % of them showed sinus rhythm and %LVEDV and LVEF were within normal range in 6 patients investigated. In recent years, surgery without angiocardiography is recommended as the diagnostic ability of UCG developed. However, care must be taken as to some rare complicated pulmonary venous connection and associated cardiac anomaly such as VSD. Also, it should be recognized that pulmonary venous beds in neonates and early infancy demonstrated various degree of mascularization , medial hypertrophy and endothelial cell proliferation in intraacinar pulmonary veins. They were more marked in cases with intracardiac type TAPVC .

Adolescent↗
PubMed1983

Local cerebral alterations in [14C-2]deoxyglucose uptake following memory formation.

In order to show changes in the local cerebral glucose utilization during an avoidance task, dry-autoradiography with [14C]deoxyglucose was employed in the present work. The following regions showed increased radioactivity following the avoidance task: nucleus ventralis thalami of the pars medialis and lateralis thalami, corpus striatum, nucleus periventricularis hypothalami, paraflocculus, stratum lacuno-moleculare, and nucleus lateralis septi. Among other regions, the stratum lacuno-moleculare of area CA1 and CA2 of the hippocampus showed increased activity apparently related to the memory formation.

Animals↗