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T Nitatori

Publications and source records attributed to T Nitatori.

At least 37 records · Page 2Linked to original sources
PubMed1995

Delayed neuronal death in the CA1 pyramidal cell layer of the gerbil hippocampus following transient ischemia is apoptosis.

The CA1 pyramidal neurons in the hippocampus are selectively vulnerable to transient ischemic damage. In experimental animals, the CA1 pyramidal neurons undergo cell death several days after brief forebrain ischemia. It remains, however, unknown whether this delayed neuronal death is necrosis or apoptosis. To investigate the degenerating processes of the CA1 pyramidal neurons in gerbil hippocampus after brief ischemia, lysosomal and nuclear alterations in the cells were examined using immunocytochemistry, in situ nick-end labeling, and Southern blotting. By light and electron microscopy, immunoreactivity for cathepsins B, H, and L, representative lysosomal cysteine proteinases, increased in the CA1 pyramidal neurons 3 d after ischemic insult, which showed cell shrinkage. By morphometric analysis, the volume density of cathepsin B-positive lysosomes markedly increased 3 d after ischemic insult, while that of autophagic vacuole-like structures also increased at this stage, suggesting that cathepsin B-immunopositive lysosomes increasing in the neurons after ischemic insult are mostly autolysosomes. Nuclei of the CA1 neurons were nick-end labeled by biotinylated dUTP mediated by terminal deoxytransferase 3 and 4 d after ischemic insult, but not in the prior stages. Simultaneously, dense chromatin masses appeared in nuclei of the neurons. By Southern blotting, laddering of DNA occurred only in CA1 hippocampal tissues obtained 4 d after ischemic insult. Confocal laser scanning microscopy demonstrated that the fragmented DNA in the CA1 pyramidal layer was phagocytosed by microglial cells. The results suggest that delayed death of the CA1 pyramidal neurons after brief ischemia is not necrotic but apoptotic.

Animals↗
PubMed1994

[Experimental study of flow rates in microcatheters using various kinds of contrast materials: comparison of imaging capability by iodine delivery rates].

In order to establish the optimal injection technique for abdominal digital subtraction angiography (DSA), flow rate measurement was performed under various combinations of all the currently available iodinated contrast materials with two types of coaxial microcatheters. In vitro study was done utilizing a plastic model of the abdominal aorta with the tip of the catheter positioned at the presumed proper hepatic artery. A total of 20ml of contrast material was injected by a pressure injector at a rate of 3 ml/sec at 300 or 600 psi, and actual flow volume was measured. Imaging capability was evaluated by calculating iodine delivery rates (IDRs). IDRs were highest in iopamidol 300 mgI/ml and iomeperol 300 mgI/ml, nonionic monomeric contrast materials of medium concentration. The results suggest that the best quality DSA images with injection to the proper hepatic artery using a coaxial microcatheter can be obtained with nonionic monomeric contrast materials of medium concentration.

Angiography, Digital Subtraction↗
PubMed1994

[Calcified false channel wall in aortic dissection].

Chest radiographs and computed tomographic images of 110 patients with chronic aortic dissection were retrospectively reviewed. Among these, calcification of false channel wall was observed in 12 cases (about 10%). Stanford type A dissection was noted in 5 cases and type B in 7 cases. Calcified false channel wall may closely simulate intimal calcification of atherosclerotic aneurysm on chest radiographs and sometimes even on CT. Careful observation of CT images with and without contrast enhancement is helpful to correctly identify the site of calcifications in the false channel wall, true channel wall, and intimal flap in the individual cases. In 3 cases calcification was present mainly in the false channel wall with no or only minimal calcification in the true channel wall. These cases may suggest that the endothelialized false channel lumen may develop atheromatous changes much more rapidly than the true lumen. According to advances in surgical and medical treatment of acute aortic dissection, radiologists may encounter cases of chronic aortic dissection with increasing frequency. Full recognition of this potential pitfall in the diagnosis of aortic dissection is important to avoid confusion.

Aged↗
PubMed1994

Neuronal differentiation of PC12 cells as a result of prevention of cell death by bcl-2.

Rat pheochromocytoma PC12 cells die when cultured in serum-free medium. Neurotrophic factors can rescue PC12 cells from cell death, and induce neuronal differentiation. To further investigate the relationship among cell death, survival, and differentiation, the bcl-2 cDNA, which is known to prevent apoptosis in various types of cells, was transfected into PC12 cells. Six monoclonal bcl-2-transfected cell lines were isolated and confirmed to express mRNA and protein product of bcl-2. The wild-type and bcl-2-transfected PC12 cells were kept to adhere to collagen-coated dishes at the initiation of serum-free experiments to avoid cellular damage due to detachment of the cells by trituration. Even under the conditions, the control PC12 cells mostly died within 24 h, when cultured in serum-free medium, whereas those expressing Bcl-2 survived even for 7 days in serum-free medium. Moreover, outgrowth of long processes in the bcl-2-transfected cells was only observed under the condition to keep the cells attached to the dishes in serum-free medium without any additive neurotrophic or growth factors. Neurofilament medium protein, which is a neuron-specific cytoskeletal component, was also expressed in the differentiated cells, suggesting that the long processes in bcl-2-transfected PC12 cells are neurites. However, neuronal differentiation of PC12 cells expressing Bcl-2 was not observed when cultured in serum-containing medium. Accordingly, survival of PC12 cells expressing Bcl-2 under the condition which cells usually die may be accompanied with neuronal differentiation.

Animals↗
PubMed1993

Lysosomal cysteine and aspartic proteinases, acid phosphatase, and an endogenous cysteine proteinase inhibitor, cystatin-beta, in rat osteoclasts.

To understand the bone resorption and lysosomal proteinases in osteoclasts, we examined by immunohistochemistry the localization of lysosomal cysteine and aspartic proteinases, acid phosphatase, and cystatin-beta in the rat tibial bone. Immunoreactivity for cathepsins B, C, H, and L, cathepsin D, acid phosphatase, and cystatin-beta was demonstrated in various cells of the bone tissue; in particular, large multinucleated osteoclasts attached to the bone surface and chondroclasts in the proximal growth plate. These cells showed intense immunoreactivity for these lysosomal enzymes and cystatin-beta. Bone surface-lining osteoblasts displayed distinct immunoreactivity for cathepsins B, C, D, H, and acid phosphatase, while osteocytes often exhibited that for cathepsins D, H and acid phosphatase. Chondrocytes in the growth plate demonstrated intense immunoreactivity for cathepsins B, D, and acid phosphatase. Immunoreactivity for cystatin-beta was detected in osteoclasts and chondroclasts only. Large, round multinucleated cells free from the bone surface exhibited weak, faint, or no immunoreactivity for the lysosomal enzymes and cystatin-beta. These results suggest that lysosomal cysteine and aspartic proteinases may play a role in the degradation of organic constituents of the bone matrix. Moreover, cystatin-beta can serve as an excellent marker protein for osteoclasts.

Acid Phosphatase↗
PubMed1992

[Percutaneous transluminal angioplasty of dialysis access shunts].

Sixteen balloon angioplasties were performed in 10 patients with upper-extremity dialysis access shunts. The initial success rate was 80% (12/15). Of the initial successes, 58% (7/12) were patent at six months and 13% (1/8) at one year. In nine cases, repeat PTA was necessary. The mean interval of patency was about four months. The longest interval was two and a half years. The complication of thrombosis of the loop shunt during PTA was successfully treated by fibrinolytic therapy.

Adult↗
PubMed1991

[Fracture of percutaneously inserted IVC filters--two cases of Günther's filter].

During the period from 1988 to 1990, percutaneous insertion of Günther vena caval filters were performed in ten patients in our institution. In two of them, fracture and partial migration of anchoring limbs were observed. Günthter's filter is an attractive device for interventional radiologist because of its technical ease of percutaneous placement and relative stability within the vein. However, our experience suggests that this device is not entirely safe and reliable. The patients should be carefully followed up with a possibility of distal migration in mind. Further structural improvement seems necessary.

Adult↗
PubMed1990

Effacement and regeneration of tactile lamellar corpuscles of rat after postnatal nerve crush.

The development of Meissner-like lamellar corpuscles was studied in rat toe pads under normal conditions and after crushing the sciatic nerve in 1- to 15-day-old animals. During normal development, rat lamellar corpuscles begin to differentiate first by postnatal day 8. By this time, sensory axons have grown up to the apex of dermal papillae and form axon terminals beneath epidermis. The terminals are ensheathed by lamellar cells derived from Schwann cells. First thin lamellae are formed around the terminals 8-12 days after birth, and the number of lamellar layers increases until the corpuscles become structurally mature by 20 days after birth. A mature corpuscle consists of two or more terminals, each surrounded by approximately 10 lamellae, all components being enclosed by an incomplete capsule. No lamellar corpuscles develop in toe pads after crushing the sciatic nerve in newborn rats, and only occasional corpuscles regenerate after nerve crush at 5 days of age. The corpuscles fail to develop because dermal papillae remain permanently denervated after crushing the nerve early postnatally. After nerve crush in 10-day-old rats, lamellar corpuscles regenerate by 1 month after the operation, but they remain underdeveloped: their number and size are smaller than normal even 1 year after injury, and their terminals are encircled only by 1-3 lamellar layers. After nerve crush in 15-day-old rats, the corpuscles recover upon reinnervation and their size and lamellation become almost normal.

Aging↗
PubMed1988

The fine structure of human Golgi tendon organs as studied by three-dimensional reconstruction.

Human Golgi tendon organs (GTOs) found at the musculo-tendinous junctions of lumbrical muscles were studied using serial sections for light and electron microscopy as the basis for a three-dimensional reconstruction. These GTOs had a thick capsule and were filled with longitudinally arranged collagen bundles. The GTOs were divided into three small compartments by septal cells: the 'neuronal compartment' containing myelinated nerve fibres, the 'terminal compartment' having axon terminals, and the 'fibrous compartment' containing only collagen fibrils. The three-dimensional reconstruction demonstrated that myelinated fibres rotated spirally before losing their myelin sheaths, and ended as unmyelinated axon terminals in the 'terminal compartment'. Axons abruptly changed course at the beginning of the terminals. Axon terminals extended many thin processes between the collagen fibrils, partially encircling them. Part of the axolemma of such indentations lacked Schwann cell coverings. The intimate contact of collagen fibrils with the axon terminals, especially in the indentations of the axons, are the presumptive site that could transmit shearing stresses to the axolemma, especially in areas devoid of Schwann cell cytoplasm.

Adult↗
PubMed1987

The cytology of human Pacinian corpuscles: evidence for sprouting of the central axon.

During the course of the studies on non-traumatized Pacinian corpuscles from normal human adults, we have frequently encountered corpuscles which have an 'apparently multiple' innervation in both light and electron microscopic preparations. On closer inspection of serial sections for both light and electron microscopy, these 'apparently multiple' axon terminals have been found in fact to be branches of the main central axon within the inner core of the corpuscle. Sprouting occurred at the trunk or at the extreme tip of the main axon, and such sprouts extended in various directions from the central axon throughout the inner core, producing tortuous and complex patterns of this 'multiple' innervation. These axonal sprouts do not have separate inner cores separated from one another, but rather are embedded in a common inner core. The presence of a common inner core thus differentiates normal axonal sprouts from the experimentally or pathologically produced multiple innervation that results form regeneration of axons in a previously denervated corpuscle. We conclude that the inner core of Pacinian corpuscles is a unique micro-environment promoting sprouting of sensory axon in the normal human adult as well as juvenile Pacinian corpuscles.

Adolescent↗
PubMed1985

Whole body intravenous digital subtraction angiography.

A new type of intravenous digital subtraction angiography using an extra large field size is reported. Excellent image quality of large field size enables better evaluation of widespread vascular disease and eliminates the need for repeated injections of contrast material in almost all patients.

Angiography↗
PubMed1983

Schwann cell basal lamina and nerve regeneration.

Nerve segments approximately 7 mm long were excised from the predegenerated sciatic nerves of mice, and treated 5 times by repetitive freezing and thawing to kill the Schwann cells. Such treated nerve segments were grafted into the original places so as to be in contact with the proximal stumps. The animals were sacrificed 1, 2, 3, 5, 7 and 10 days after the grafting. The grafts were examined by electron microscopy in the middle part of the graft, i.e. 3-4 mm distal to the proximal end and/or near the proximal and distal ends of the graft. In other instances, the predegenerated nerve segments were minced with a razor blade after repetitive freezing and thawing. Such minced nerves were placed in contact with the proximal stumps of the same nerves. The animals were sacrificed 10 days after the grafting. Within 1-2 days after grafting, the dead Schwann cells had disintegrated into fragments. They were then gradually phagocytosed by macrophages. The basal laminae of Schwann cells, which were not attacked by macrophages, remained as empty tubes (basal lamina scaffolds). In the grafts we examined, no Schwann cells survived the freezing and thawing process. The regenerating axons always grew out through such basal lamina scaffolds, being in contact with the inner surface of the basal lamina (i.e. the side originally facing the Schwann cell plasma membrane). No axons were found outside of the scaffolds. One to two days after grafting, the regenerating axons were not associated with Schwann cells, but after 5-7 days they were accompanied by Schwann cells which were presumed to be migrating along axons from the proximal stumps. Ten days after grafting, proliferating Schwann cells observed in the middle part of the grafts had begun to sort out axons. In the grafts of minced nerves, the fragmented basal laminae of the Schwann cells re-arranged themselves into thicker strands or small aggregations of basal laminae. The regenerating axons, without exception, attached to one side of such modified basal laminae. Collagen fibrils were in contact with the other side, indicating that these modified basal laminae had the same polarity in terms of cell attachment as seen in the ordinary basal laminae of the scaffolds.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Nearest-neighbor distance of intermediate filaments in axons and Schwann cells. Distinction between axons and schwann cell processes in the denervated and reinnervated peripheral nerves.

To distinguish axons from Schwann cell processes in the denervated (Büngner's bands) and reinnervated peripheral nerves, the nearest-neighbor distance of intermediate filaments (NND) was measured in axons and Schwann cells from denervated and subsequent regenerating peripheral nerves. It was revealed that the NND was much larger in regenerating axons (41.9 +/- 14.1 nm) than in Schwann cell processes (23.1 +/- 7.1 nm in regeneration and 19.7 +/- 5.8 nm in denervation). In addition, the NND was also measured in the normal adult and developing peripheral nerves, and it became clear that in all cases the NND in axons (29.0-41.9 nm) was larger than in Schwann cells (19.7-23.1 nm). Thus, it can be generally considered that the NND is larger in axons than in Schwann cells. This fact can be used for the distinction between axons and Schwann cell processes, when the latter have a profile similar to that of the former as in Büngner's bands and in the regenerating nerves.

Animals↗
PubMed1983

Ultrastructure of the corpuscular nerve ending in the lymph heart of the turtle (Pseudemys scripta elegans).

Corpuscular nerve endings were found in the tunica externa of the lymph heart of a turtle (Pseudemys scripta elegans). They consisted of axon terminals and surrounding cellular lamellae. Serial thin sections of one such presumable sensory corpuscle were made and reconstructed for the three-dimensional analysis of the corpuscle, with special reference to the axon terminals. It was revealed that axon terminals ramified at several points within the corpuscle and formed varicosities of various sizes ranging from 1.0 to 3.0 microns in diameter in their courses. Such varicosities contained an abundance of mitochondria as well as clear and granular vesicles 500 to 800 A in diameter. Finger-like protrusions often projected from the axon terminals into the interlamellar spaces. The lamellae consisted of several thin cytoplasmic processes of modified Schwann cells. The corpuscle was enclosed in an incomplete capsule consisting of a thin layer of cellular processes. The corpuscular nerve endings may represent pressoreceptors in the wall of the lymph heart.

Animals↗