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Biomedical subjects

M Shimada

Publications and source records attributed to M Shimada.

At least 775 records · Page 43Linked to original sources
PubMed1986

Differential effects of kainic-acid-induced hippocampal lesions on the acquisition of the jump-box avoidance task in mice.

This research examined the effects of kainic-acid (KA)-induced hippocampal lesions on the acquisition of a jump-box avoidance task in mice. When the hippocampal lesion was unilateral, mice with lesions in the lateral portion of the CA1 region showed deficits in acquisition while those with lesions in the CA3 region and/or the medial portion of the CA1 region did not. When the hippocampal lesion was bilateral, on the other hand, mice with lesions in the CA3 region and/or the lateral portion of the CA1 region were deficient in acquisition while those with lesions in the medial portion of the CA1 region were not. Among the mice with various KA-induced hippocampal lesions avoidance responses were not correlated with the level of open field activity, indicating that acquisition differences observed are not dependent upon, nor secondary to, levels of spontaneous activity. These results strongly suggest that there exist regional differences in the involvement of hippocampal pyramidal cell layers in acquisition of the jump-box avoidance task: both the CA3 region and the lateral portion of the CA1 region are involved in acquisition, while the medial portion of the CA1 region is not.

Animals↗
PubMed1986

Pathological study on a severe sialidosis (alpha-neuraminidase deficiency).

A 56-day-old infant with alpha-neuraminidase deficiency, whose clinical features included severe edema of extremities and ascites which resembled those in severe infantile sialidosis, was autopsied. Perforation, whose pathogenesis was unclear, was found on the descending portion of the duodenum. Light and electron microscope studies showed that neurons in the cerebral and cerebellar corticies, and the thoracic spinal cord contained membrane-bound vacuoles but no membranous cytoplasmic bodies. Zebra bodies were found only in the neurons of the spinal cord. The neurons in the paraganglion and in the Auerbach's myenteric plexus were also distended with numerous membrane-bound vacuoles. Hepatocytes, endothelial cells and Kupffer cells in the liver and glomerular and tubular epithelial cells in the kidney were swollen with a number of vacuoles, although the patient showed none of the clinical features of renal involvement. These pathological changes were similar to those in nephrosialidosis reported by Le Sec et al. [Arch Fr Pediatr 35:819-829 (1978)].

Cerebral Cortex↗
PubMed1986

Primary perianal actinomycosis over a thirty year period.

A 50-year-old Japanese man had had abscesses and draining fistulas in the perianal region. These lesions recurred, despite surgical treatment such as incision and drainage over a 30 year period. "Sulfur granules" were found in the pus from the abscess and Actinomyces israelii was cultured. Ampicillin-cloxacillin treatment lead to healing. The patient died 4 months later with a hepatoma and multiple metastases.

Abscess↗
PubMed1986

Quantitative synaptic changes on Purkinje cell dendritic spines of rats born from streptozotocin-induced diabetic mothers.

This study was undertaken to elucidate the quantitative synaptic changes on the dendritic spines of the Purkinje cells of the rats born from streptozotocin-induced diabetic mothers. The brains of the experimental rats including cerebellum decreased in weight and in size on days 1, 30 and 70 as compared to those of the age-matched controls. Ultrastructural observation did not show any significant destructive changes in their cerebellum on days 30 and 70. However, the measurements for the synaptic length and area of dendritic spine of their Purkinje cells on days 30 and 70 showed an increase of about 10% in the former and of about 42% in the latter as compared to those in the age-matched control. These evidences suggest a presence of compensation in the brains thus damaged.

Animals↗
PubMed1986

The regulation by growth hormone of microsomal testosterone 6 beta-hydroxylase in male rat livers.

The relationship between growth hormone and testosterone (T) 6 beta-hydroxylase was investigated in normal and hypophysectomized (hypox) male rats. The administration of human growth hormone (hGH) by either intermittent injections or continuous infusion to normal and hypox rats decreased the activity of T 6 beta-hydroxylase in hepatic microsomes. Hypophysectomy did not reduce, but rather increased the 6 beta-hydroxylase activity, while the 16 alpha-hydroxylase activity decreased. These results, together with the data from a Western blot, indicate that growth hormone acts as a repressive factor for the expression of T 6 beta-hydroxylase in a manner different from the regulation of T 16 alpha-hydroxylase.

Animals↗
PubMed1986

Effect of growth hormone and ectopic transplantation of pituitary gland on sex-specific forms of cytochrome P-450 and testosterone and drug oxidations in rat liver.

The effects of growth hormone and ectopic transplantation of pituitary gland on the amounts of sex-specific cytochrome P-450, P-450-male and P-450-female, and the activities of testosterone and drug hydroxylases in male rat liver microsomes were studied. Hypophysectomy decreased the content of P-450-male, without changing the total cytochrome P-450 level. The continuous infusion of growth hormone into hypophysectomized rats and the transplantation of pituitary gland under the renal capsule caused a further decrease in P-450-male content and an expression of P-450-female. In contrast, the intermittent injection of growth hormone into hypophysectomized rats increased P-450-male content to the level seen in intact male rats. The activities of testosterone 2 alpha- and 16 alpha-, but not 6 beta-, 7 alpha-, or 15 alpha-hydroxylase, were changed in association with the level of P-450-male by these treatments. Anti-P-450-male immunoglobulin G inhibited testosterone 2 alpha- and 16 alpha-hydroxylations, but not 6 beta-, 7 alpha- or 15 alpha-hydroxylation. These results indicate that growth hormone regulates the expression of P-450-male responsible for testosterone 2 alpha- and 16 alpha-hydroxylations. The metabolism of 7-propoxycoumarin, benzo(a)pyrene and aminopyrine also changed with the content of P-450-male, although the correlation was less than that observed with testosterone 2 alpha- and 16 alpha-hydroxylation.

Animals↗
PubMed1986

Effects of phenobarbital, 3-methylcholanthrene and polychlorinated biphenyls on sex-specific forms of cytochrome P-450 in liver microsomes of rats.

The effects of treatment with phenobarbital, 3-methylcholanthrene or polychlorinated biphenyls (PCB) on the amounts of sex-specific forms of cytochrome P-450, namely P-450-male and P-450-female, in male and female rats were studied. Although treatment with phenobarbital, 3-methylcholanthrene or PCB markedly increased the total amount of hepatic cytochrome P-450, P-450-male and P-450-female were rather decreased or not significantly changed. Thus, the percentages of P-450-male and P-450-female in the total cytochrome P-450 were decreased in liver microsomes from the treated rats. The increases in specific cytochrome P-450, such as P-448-H, P-448-L, and P-450I-c accounted for the increase in the total amount of cytochrome P-450 in the treated rats. The treatment with phenobarbital or PCB increased the activities of testosterone 16 alpha-hydroxylase, benzo(a)pyrene hydroxylase and aminopyrine N-demethylase more markedly in female rats than in male rats. Similarly, the treatment with 3-methylcholanthrene increased benzo(a)pyrene hydroxylase more markedly in female rats. Therefore, the sex-differences in testosterone 16 alpha-hydroxylase, benzo(a)pyrene hydroxylase, and aminopyrine N-demethylase activities became smaller after the drug treatment. These results indicate that sex-specific P-450-male and P-450-female were unaffected, or even depressed by the agents in some cases.

Animals↗
PubMed1986

Autoradiographic study of [35S]-cysteine and [1-14C]-cystine in pregnant and neonatal mice.

The distribution and fate of 35S from [35S]-cysteine and 14C from [1-14C]-cystine, both precursors to taurine in 17-day pregnant mice and (1-day-old) neonates were investigated by whole-body autoradiography following IV injection for the pregnant mice and IP injection for the neonates. Survival intervals were 30 min, 3 hr. In the dam, 35S and 14C were both highly incorporated into the pancreas. As very low uptake of [35S]-taurine in the pancreas was found in a previous study, it is reasonable to suggest that most radioactivity found in the pancreas represents cysteine. In maternal brain, brown fat, and myocardium, optical density and relative ratio (ODs of 35S and 14C in each tissue and organ/ODs of 35S and 14C in the blood) of 35S were significantly higher than those of 14C, assuming that most of 35S might be present as taurine in these regions. In the developing brain, 35S was found mainly in the differentiating neurons of the cortical plate, including the primordial hippocampal cell layer, and of the cerebellar cortical plate. Relative ratios of 35S in these cerebral regions were significantly higher than those of 14C, suggesting that most of 35S represents taurine.

Animals↗
PubMed1986

Very long-chain fatty acids in erythrocyte membrane sphingomyelin: detection of ALD hemizygotes and heterozygotes.

We used mass fragmentography to analyze a very long-chain fatty acid composition of erythrocyte membrane sphingomyelin. The content of hexacosanoic acid (C26:0), tetracosanoic acid (C24:0) and docosanoic acid (C22:0) in adrenoleukodystrophy (ALD) hemizygotes and heterozygotes was significantly higher than in controls. Although the ratio of C26:0 to C22:0 in 18 of the 46 controls was in the range of ALD heterozygotes, the absolute content of C26:0 and C24:0 in controls did not overlap with ALD hemizygotes or heterozygotes. The content of C26:0 and C24:0 is more reliable for detection of ALD hemizygotes and heterozygotes than the ratio of C26:0 to C22:0 when red cell sphingomyelin is used for diagnosis.

Adolescent↗
PubMed1986

Effects of hypophysectomy and growth hormone treatment on sex-specific forms of cytochrome P-450 in relation to drug and steroid metabolisms in rat liver microsomes.

Hypophysectomy decreased the content of a male specific cytochrome P-450, P-450-male, in male rats, while it expressed P-450-male and completely depressed a female specific cytochrome P-450, P-450-female, in female rats. Intermittent injections of human growth hormone (GH), which mimic the secretion in males, restored P-450-male in hypophysectomized (Hypox) male rats and partially restored P-450-female in Hypox female rats. Continuous infusion of GH, which mimics the female secretion pattern, into Hypox male rats caused a further decrease in P-450-male content, and it caused the expression of P-450-female. In Hypox female rats, the same treatment depressed P-450-male and expressed P-450-female to the level of an intact female. These results indicate that the diurnal changes in the pattern of serum growth hormone level regulate the expression of P-450-male and P-450-female. The activities of testosterone 2 alpha- and 16 alpha-hydroxylases were closely correlated to P-450-male content with the correlation coefficients (r) of 0.955 and 0.929, respectively. Benzo(a)pyrene hydroxylation was also correlated to P-450-male content (r = 0.850). Aminopyrine N-demethylation and propoxycoumarin O-depropylation were correlated to less extents (r = 0.692 and r = 0.720), while aniline hydroxylation and O-ethylresorufin O-deethylation were not correlated to P-450-male content. These results indicate that testosterone 2 alpha- and 16 alpha-hydroxylations are closely dependent, but the metabolism of a variety of drugs are dependent to different extents on P-450-male in rat liver microsomes.

Animals↗
PubMed1986

Diazo-reaction positive substance observed in the cortex of Chattonella antiqua.

In order to investigate the causative factors responsible for removal of mucous coat from the gill lamellae of young yellowtail, Seriola quinqueradiata by red tide, diazo-reactions were employed for planktons and their media. The concentration of NO2- in the medium containing the raphidophyceae, Chatonella antiqua (ca 2000 cells/ml), was 0.70 +/- 0.05 (mu g/ml +/- SEM). In addition, diazo-reaction positive substances (NOx) which may degenerate the mucous, was highly concentrated in the cortex (perikaryon) of Chattonella antiqua. Morphologically, mucocysts, and chloroplats were likewise present in the cortex. Mucocysts were packed with fine fibrous content. Histochemically, the mucocysts were stained with PAS and had an abundance of nitrogen oxides (NOx). We observed discharge of the fibrous material from the mucocysts. These results suggest that when Chattonella antiqua is passing between the gill lamellae, NOx discharged from the mucocysts may act on the mucous, leading to the degeneration and concomitant removal of the mucous coat from gill lamellae.

Animals↗
PubMed1985

Pituitary regulation of sex-specific forms of cytochrome P-450 in liver microsomes of rats.

Effects of hypophysectomy and treatment with testosterone or estradiol on the sex-specific forms of cytochrome P-450, P-450-male and P-450-female, were examined. The amounts of P-450-male as well as drug oxidation activities were decreased by hypophysectomy of male rats. In female rats, drug oxidation activities were increased by hypophysectomy, which was associated with the disappearance of P-450-female and the appearance of P-450-male. Treatment of hypophysectomized female rats with testosterone or estrodiol effected minor changes in the amounts of P-450-male.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1985

Ultrastructural study on a severe infantile sialidosis (beta-galactosidase-alpha-neuraminidase deficiency).

This study was undertaken to elucidate ultrastructural changes in a severe infantile sialidosis. The materials examined in this study consisted of biopsied rectal mucosa and autopsied small intestine, liver and kidney. In the biopsy sample, axons contained a number of pleomorphic electron dense bodies, and numerous membrane-bound vacuoles were found in Schwann's cells, fibroblasts, endothelial cells, lymphocytes and plasma cells. In autopsy samples, neurons in Auerbach's myenteric plexus of the small intestine were filled with a number of membranous cytoplasmic bodies, pleomorphic dense bodies and vesicles containing dense materials. Hepatocytes in the liver, and glomerular and tubular epithelial cells in the kidney were also extended by a number of membrane-bound vacuoles. These ultrastructural changes in severe infantile sialidosis closely resemble those in GM1-gangliosidosis type 1.

Biopsy↗