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Biomedical subjects

M Ohata

Publications and source records attributed to M Ohata.

At least 127 records · Page 7Linked to original sources
PubMed1981

Cerebral blood flow and glucose utilization following opening of the blood-brain barrier and during maturation of the rat brain.

This paper reviews that relation between regional cerebral blood flow (rCBF) and local cerebral glucose utilization (LCGU) under normal conditions of altered functional activity, following disruption of the blood-brain barrier by osmotic stress or hypertension, and during development and maturation of the rat brain. rCBF usually increases in parallel with LCGU when neuronal activity in the central nervous system increases. However, disruption of the blood-brain barrier disturbs this coupling between rCBF and LCGU. the blood-brain barrier, which is located at the continuous cerebrovascular endothelium, protects against brain edema and helps to maintain normal cerebral metabolism. When the barrier is disrupted by osmotic stress or by hypertension, LCGU increases markedly, due to increased neuronal activity, and brain edema develops. rCBF does not increase, however, possibly because brain edema prevents cerebral vasodilatation. rCBF and LCGU follow separate time courses during development and maturation of the rat brain. Both parameters increase between the ages of 1 and 3 months, but rCBF continues to rise from 3 to 12 months when LCGU simultaneously falls. The divergent time courses of these two parameters of brain functional activity may reflect an age-related change in the sensitivity of the cerebrovascular bed to metabolic factors that regulate rCBF.

Aging↗
PubMed1980

Vitamin D and parathyroid hormone degradation by the kidney.

Parathyroid function is controlled by the regulation of hormone secretion as well as degradation, through the action of calcium and vitamin D derivatives. In order to clarify the relationship between vitamin D metabolism and parathyroid degradation system, parathyroid hormone (PTH)-degrading activities of the kidney were measured in vitamin D repleted and depleted rats given various derivatives of vitamin D. Kidney calcium content rose markedly in animals given 10 microgram/kg 1 alpha(OH) vitamin D3 and 1,000 microgram/kg dihydrotachysterol and PTH-degrading activity rose only in these animals, indicating a parallelism between kidney calcium content and PTH-degrading activity of the kidney tissue. These vitamin D derivatives also increased the PTH-degrading activity of kidney tissue when they were added in vitro.

Animals↗
PubMed1980

Pathogenesis of spontaneous pneumothorax. With special reference to the ultrastructure of emphysematous bullae.

We have performed 253 thoracotomies among a total of 334 cases of spontaneous pneumothorax during the past 17 years, subjecting 126 of these surgical cases to histologic examination by light microscope. Recently, we have classified 54 emphysematous bullae as Reid type 1 or 2 and have examined these, as well as giant bullae, by scanning electron microscope. This revealed exterior surface differences among the three types of cysts: type 1 exhibits a marked absence of mesothelial cells, whereas type 2 and giant bulla do not. At the bases of bullae, deteriorated pulmonary parenchyma, exposed to alveolar space, shows reticulated trabecula-like structures. Our study supports the possibility of air leaking through the wall of the bulla into the pleural cavity at a certain level of pressure, thus emphasizing the role of pleural mesothelial cells in the genesis of spontaneous pneumothorax.

Adult↗
PubMed1979

Electron microscope study on the bat testicular interstitial cell with special reference to the cytoplasmic crystalloid.

The testicular interstitial cell of the bat, Myotis schreibersi (Temmink), captured late in August was electron microscopically investigated. The cytoplasm of Myotis interstitial cells is packed by strikingly numerous mitochondria with many electron dense small matrix granules, endoplasmic reticulum and variable numbers of osmiophilic lipid droplets. The Myotis interstitial cell is characterized by alternate development of the SER and RER: In some Leydig cells the major part of the cytoplasm is packed by tubular SER, whereas in others this apparently is replaced by abundant free ribosomes containing sparse cisternae of the RER. These changes in the amounts of ser and RER are likely reversible and probably reflect functional alterations of Leydig cells of the bat, a hibernator. The Myotis interstitial cell possesses small cytoplasmic crystalloids composed of regularly oriented, compressed tubules, 20-28 m mu thick, which are continuous to the tubular SER (SER derived crystalloids). Type I and type II crystalloids are classified, which show, in suitable planes of section, honeycomb-like and fabric-like patterns, respectively. The Myotis Leydig cell extends cytoplasmic processes of irregular shape and long microvilli, the latter often conglomerates on the cell body or cytoplasmic processes. The entire surface of the cell including the processes is completely surrounded by a basal lamina.

Animals↗
PubMed1979

Electron microscopic study on the testicular interstitial cells in the mouse.

The interstitial tissue of the mouse testis contains, besides mature and immature Leydig cells, fibroblasts, occasional plasma cells and a considerable number of macrophages abutting on the Leydig cells. Mature Leydig cells extend filopodia into dilated portions of the intercellular space. Along the cell surface deep hollows are frequently formed which contain numerous filopodia protruded from the plasma membrane limiting the hollow. This unique structure is tentatively designated the "basal infolding-like structure." Abundant SER is classified into the tubular and vesicular forms. The former is composed of interconnected tubules which may form flattened, partially fenestrated cisternae in some areas. The latter form is composed of vesicles of variable sizes. The tubules probably transform into the vesicular form, possibly reflecting the functional phases of Leydig cells. Thus, among vesicles, patches of tubules with smaller calibers may be detectable. Membranous whorls composed of concentric lamellar stacks of flattened, partially fenestrated cisternae of the SER are frequently observed, enclosing a mitochondrion, lipid droplet or microbody in their center. A typical annulate lamellae are occasionally found in the cytoplasm or in the whorl which is continuous to the membranes of the ER. Small foci of the RER are detected and sometimes dilations of its cisternae are observed. Polysomes are distributed not only in the RER foci, but also throughout the cytoplasm intervening among the SER membranes. Mitochondria possess tubular cristae and occasionally contain sparse ribosome-like granules. Out of several Golgi complexes dispersed in the cytoplasm, the juxtanuclear one contains a diplosome and an occasional solitary cilium. Relatively numerous microbodies are scattered in the cytoplasm. Lipid droplet content varied strongly from cell to cell, probably suggesting variable intensities of steroid synthesis. In the peripheral cytoplasm, large vacuoles were found, probably derived from the testosterone-containing SER. These possible secretory vacuoles occurred close to the plasma membrane, suggesting emiocytotic release of the contents. The basal lamina was restricted to certain areas of the plasma membrane.

Animals↗
PubMed1978

[Degradation of the parathyroid hormone in the kidney and liver (author's transl)].

The cleavage of the parathyroid hormone has been reported to take place in various peripheral tissues, especially in the kidney and liver. In order to claify the mechanism of such a degradation, bovine PTH (bPTH 1--84) and its synthetic N-terminal peptide (bPTH 1--34) labelled with 125I by the chroramine-T method (125I-bPTH 1--84) and (125I-bPTH 1--34) or labelled with horseradish peroxidase Pox-125I-bPTH 1--84 and Pox 125I-bPTH 1 34) were used to study the disappearance from the blood stream and degradation and retension in the kidney and liver after intravenous injections in male Wiastar rats, weighing approximately 200g. Degradation of PTH was also studied in vitro, using isolated cells and a homogenate of the kidney and liver. PTH labeled with 125I and Pox was more readily degraded by the kidney than PTH labelled with 125I alone, but the opposite was found in the degradation by the liver. Isolated intact kidney cells degraded PTH less efficiently than the homogenate, but the isolated intact liver cells degraded PTH more efficiently than the homogenate, indicating the prominence of an intracellular mechanism of degradation in the kidney and an extracellular mechanism in the liver.

Animals↗
PubMed1978

Transmission electron microscope observation of epithelial cells with single cilia in intrahepatic biliary ductules of bats.

Cells with long single cilia arising from basal bodies in the apical cytoplasm were occasionally revealed in the bile ductular epithelia of bats (Miniopterus schreibersi (Kuhl), Myotis macroductylus (Temminck) and Rhinolophus cornutus (Temminck)). The basal body (distal centriole) was associated witha proximal centriole, so the basal structure was of "two centriole type." In cross sections of the long tapering cilia the arrangement of cilary microtubules was determined. In the most proximal portion of the cilia doublet microtubules were arranged in the 9+0 pattern, while in more distal portions alteration and diminution of the doublet fibers occurred, splitting entirely into single microtubuli which were most frequently rearranged in the 6+1 or 7+1 pattern. The occurrence of the 9+0 fiber pattern and the basal structure of "two centriole type" suggested that the biliary ductular cilia might be sensory or chemoreceptive in nature and not motile. Similar cilia are expected to be found distributed widely in the epithelia of excretory ductal system of large exocrine glands of vertebrate species.

Animals↗
PubMed1978

Occurrence of centrioles in interphasic hepatocytes of bat and chicken.

Occurrence of centrioles in non-dividing hepatocytes was examined by electron microscopy in the bat, Miniopterus schreibersi (Kuhl) and Myotis macrodactylus (Temminck), and the chicken. In both species centrioles were mostly found in the apical hyaloplasmic halo which was distinct in the chicken but rather indistinct in the bat. There was no difficulty in locating centrioles in the hepatocytes of either species. In the chicken centrioles were found in the attenuated apical cytoplasmic areas of 4-6 hepatocytes surrounding the bile canaliculus, giving us the impression that the occurrence of centrioles in non-dividing hepatocytes might be more frequent in the chicken than in the bat. The centrioles found in non-dividing bat and chicken hepatocytes apparently formed diplosomes. Neither multiple centrioles (comprising more than three) nor centriolar replications were found. Single cilium formation from the centrioles was not observed in either species.

Animals↗
PubMed1978

[Significance of computed tomography in therapeutic diagnosis of brain tumors (author's transl)].

Because of its noninvasive property of direct imaging of the size and shape of the lesion, CT scan is significant not only for the diagnosis of the brain tumors, but also for the assessment of its chronological and/or therapeutic change in size. Contrary to the conventional cerebral angiography and contrast encephalography, CT scan is feasible to detect the tumor repeatedly at short intervals. From March 1976 to October 1977, 197 cases of brain tumors were examined by CT, 6 tumors (1 pineal tumor, 2 cerebellar vermian tumors and 3 supratentorial tumors) of which were radiated after the initial CT scan and re-examined by CT at every 400-1,000 rads radiation, and their grade of radiosensitivity could be evaluated. Immediately after the radiation of 400 rads for five days to the large pineal tumor of a 16-year-old boy, CT exactly showed the markedly diminished size of the tumor, and the tumor disappeared on CT after the 4,000 rads radiation. Cerebellar vermian tumors suspected of medulloblastoma were also diminished in size on CT after the 600 rads radiation. One supratentorial tumor was radiosensitive and disappeared at the end of radiation therapy. Other supratentorial tumors were not changed on CT during the radiation. Procedures for the therapeutic diagnosis, when combined with CT, can easily indicate whether the tumor is radiosensitive or not, without any invasive examination and/or operation.

Adolescent↗
PubMed1978

[Radioisotope cisternographic study on intracranial arachnoid cyst (author's transl)].

The dynamics of the CSF circulation in six cases of intracranial arachnoid cysts was examined by RI cisternography suing 0.5 to 1.0 mCi of 169Yb DTPA or 50 to 100 microCi of 131I HSA injected into the lumbar subarachnoid space. Serial scintigrams were obtained with rectilineal scintillation scanner at 2, 4, 6, 24 and 48 hours after injection. The communication of the cavity of arachnoid cyst and subarachnoid space was recognized in all cases. The cysts were best visualized at 24 hours in most cases. Four patterns of the entry and stasis of RI in cysts were observed as follows, 1) rapid filling of RI into the cyst and delayed clearance, 2) both rapid filling and clearance, 3) slow filling and delayed clearance, 4) no filling.

Adolescent↗