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Biomedical subjects

K Kadota

Publications and source records attributed to K Kadota.

246 records · Page 14Linked to original sources
PubMed1973

Isolation of coated vesicles, plain synaptic vesicles, and flocculent material from a crude synaptosome fraction of guinea pig whole brain.

Two vesicular fractions and one nonvesicular fraction were prepared from crude synaptosomes by differential centrifugation and salting out with ammonium sulfate. Fraction 1 contained a mixture of coated vesicles, material thought to be derived from breakdown of the coats (shell fragments), and plain synaptic vesicles. Fraction 2 contained a mixture of plain synaptic vesicles and flocculent material. Fraction 3 contained flocculent material only. Fractions 1 and 3 were partially purified by passage through a Sephadex column. Fraction 3 contained no shell fragments but contained finer flocculent material which, it is suggested, is composed of unit particles either occurring singly or linked together into chainlike or amorphous aggregates. Each unit particle appears to have four subunits and is here referred to as a tetrasome. Tetrasomes sometimes appear to be attached to the surfaces of the plain synaptic vesicles. Also, it is possible that aggregates of tetrasomes form part of the structure of the presynaptic dense projections.

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PubMed1969

The "vesicle in a basket". A morphological study of the coated vesicle isolated from the nerve endings of the guinea pig brain, with special reference to the mechanism of membrane movements.

Five points are discussed regarding the vesicular structure isolated by fractionation techniques from the brain and liver of the guinea pig. 1. One type of vesicle, fixed by OsO(4) and shown in thin sections, is identified with the coated vesicle that has been observed in many varieties of tissues. 2. The vesicle contained in a spherical polygonal "basketwork" shown by the negative-staining techniques is identical with the coated vesicle shown in sections. 3. Despite minute observation of this basketwork we could not confirm the existence of "hairlike projections" extending from the convex cytoplasmic surface of the vesicle. We are inclined to believe, therefore, that the hairlike projections are actually the superimposed visual images of the regular hexagons and pentagons of the network composing the basketwork. 4. We repeat the hypothesis originally advanced by Roth and Porter (1) that the "coating" of the coated vesicle plays a role in the mechanism of the infolding and fission of the membrane; we suggest that these events are caused by the transformation of the regular hexagons (of the coating) into regular pentagons. 5. Finally, we make a suggestion as to the nature of those vesicles which have on their surface subparticles which look like "elementary particles (2)."

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PubMedDate not supplied

Foci of altered hepatocytes in a fox squirrel (Sciurus niger) with haemochromatosis.

Numerous minute milky white foci were distributed throughout the dark brown liver in an adult male fox squirrel. Histologically, the hepatic focal lesions were composed of large eosinophilic granular hepatocytes, which were mostly positive for glutathione S-transferase mu antigen and proliferating cell nuclear antigen. Electron microscopy demonstrated an increased number of mitochondria. These features corresponded to those in the eosinophilic type of foci of altered hepatocytes. Berlin blue stain showed severe haemosiderin deposition in hepatocytes, except in the focal lesions. Since the fox squirrel is known to be liable to develop congenital porphyria, it is suggested that the hepatic anomalies described may be closely associated with the development of porphyria.

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PubMedDate not supplied

Mycoplasma bovis-associated suppurative otitis media and pneumonia in bull calves.

Outbreaks of Mycoplasma bovis-associated otitis media and pneumonia occurred on four beef cattle farms in Hokkaido, Japan between 2000 and 2001. The morbidity and mortality were estimated at 8-40 and 30-100%, respectively. Eight calves with bilateral ear droop and exudative otitis media were examined bacteriologically and histopathologically. M. bovis was isolated post mortem from nasal swabs and from the ears, lungs, lymph nodes (cranial and pulmonary), brain and heart of all calves. At necropsy, suppurative exudates were observed in the tympanic bullae of all cases. Numerous abscesses were also found in the petrous portion of the temporal bone and lungs in seven cases. Histopathologically, the exudates within the tympanic bullae consisted of a mixture of neutrophils, necrotic cell debris and fibrin, and the tympanic mucosa was thickened with neutrophil and macrophage infiltration and proliferation of fibrous connective tissue. Pulmonary lesions included extensive foci of coagulative necrosis surrounded by numerous neutrophils. Hepatocytes or renal tubular epithelial cells were enlarged with hyaline cytoplasmic inclusions in four calves. Immunohistochemical labelling confirmed the presence of M. bovis antigen in the cytoplasm of the inflammatory cells in the middle ear, temporal bone and lungs, and was also demonstrated within the cytoplasmic inclusions of the hepatocytes and renal tubular epithelial cells. Ultrastructurally, mycoplasma-like organisms, 200-500 microm in diameter, were found within not only hepatocytes and renal tubular epithelia but also within axons of the facial nerves. The present results show that M. bovis spreads to multiple organs and is capable of invading various kinds of host cell. The intracellular localization may be favourable for evading host immune responses.

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PubMedDate not supplied

Haemangiopericytoma in a calf.

After castration, a Japanese Black male calf developed subcutaneous tumours near the scrotum. They were surgically excised, and no recurrence was detected two years after surgery. The tumours were characterised by neoplastic cells concentrically arranged around blood vessels of various sizes. The neoplastic cells contained many cytofilaments, and the majority of the cells expressed smooth muscle actin, but focal densities were not found. On the basis of the immunohistochemical and ultrastructural features, the tumours were considered to be of pericyte origin.

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PubMedDate not supplied

Differentiated basal cell carcinoma in a Cape clawless otter (Aonyx capensis).

Basal cell carcinoma with folliculoapocrine differentiation was diagnosed in a male Cape clawless otter (Aonyx capensis) aged >8 years. A tumour mass in the left submandibular region was removed surgically, but another tumour subsequently appeared on the left cheek. In addition, necropsy revealed a subcutaneous tumour mass at the excision site. Histologically, the tumours consisted of lobules or islands of basaloid cells, frequently with central keratinization and tubular structures. The presence of isthmic keratinization and apocrine differentiation was confirmed by immunolabelling for cytokeratins, and a few cytokeratin-positive tumour cells were found in a submandibular lymph node. The neoplasm, characterized by its metachronous and recurrent nature, metastasis to the local lymph node and amyloidosis, closely resembled human differentiated basal cell carcinoma, both clinically and pathologically.

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