Biomedical subjects

A Ohtsuka

Publications and source records attributed to A Ohtsuka.

At least 109 records · Page 6Linked to original sources

PubMed1993

Neurons with strongly negative-charged surface-coats in adult rat brain as detected by staining with cationic iron colloid.

Light microscopy of tissue sections stained either with cationic iron colloid (pH 1.0-2.0) and nuclear fast red or with this colloid and thionin showed that the adult rat brain contains a considerable number of neurons which are strongly negative-charged by being coated with sulfated proteoglycans such as chondroitin sulfates. These neurons are distributed mainly in the cerebral cortex, hippocampus, zona incerta, medial and lateral cerebellar nuclei, ventral pontine nuclei and certain other areas. In the hippocampal formation, the strongly negative-charged cells seem identical with the GABAergic inhibitory interneurons reactive to the lectin Vicia villosa agglutinin. Neurons, including the GABAergic Purkinje's cells, of the cerebellar cortex showed no reaction to our cationic iron colloid at pH values of 1.0-2.0. Many non-GABAergic pyramidal cells in the lamina ganglionalis of cerebral cortex and many non-GABAergic large neurons of the ventral pontine nuclei were highly reactive to our colloid at pH values of 1.0-2.0. This suggests that our cationic iron colloid at pH values of 1.0-2.0 mainly stains certain subtypes of GABAergic neurons as well as some non-GABAergic neurons projecting long associational or commissural fibers.

Animals↗

PubMed1993

The occurrence in the human brain of neurons with strongly negative-charged proteoglycans.

The occurrence of neurons with strongly negative-charged surface-coats was confirmed in the human brain. Cerebral cortical tissue pieces (Area 19 of Brodmann), which had been removed in surgery from a 45-year-old Japanese man with meningioma were fixed with formalin. These specimens were cut into sections, stained with fine cationic iron colloid at pH value 1.0-2.0, treated for Prussian blue reaction, counter stained with carbolthionin, and observed with a light microscope. The observations indicated that some large-sized pyramidal cells in the ganglionic lamina were strongly negative-charged or coated with sulfated proteoglycans, though where these cells projected to could not be determined.

Brain Chemistry↗

PubMed1993

Microcirculatory patterns in adult rat cerebral hypophysis: a scanning electron microscope study of replicated specimens.

The blood vascular bed of the cerebral hypophysis in the adult rat was replicated completely or incompletely by arterial injection of different amounts of methacrylate resin, to be observed with a scanning electron microscope. Complete replication confirmed our previous findings (Murakami et al., 1987) on the distribution and structure of the vascular beds in and around the hypophysis of the rat. One long major and several minor portal routes (vide infra) were reproduced sufficiently together with the systemic veins of the posterior lobe. Incomplete replication demonstrated that resin flows: 1) via the long portal vessels from the median eminence and neural stalk to the anterior lobe; 2) via the accessory long portal vessels from the subependyma to the anterior lobe; 3) via the short portal vessels from the posterior lobe to the anterior lobe; 4) via the neuro-intermedial portal vessels from the posterior lobe to the intermediate lobe; 5) via the intermedio-distal portal vessels from the intermediate lobe to the anterior lobe; and 6) via the tuberal portal vessels from the tuberal lobe to the anterior lobe. Incomplete replication also demonstrated that resin in the median eminence and neural stalk is drained preferentially into the anterior lobe via the long portal vessels, and that resin in the posterior lobe is drained mainly into the systemic veins. We were unable to demonstrate a retrograde resin flow from the anterior lobe to the median eminence, subependyma, neural stalk, intermediate lobe and posterior lobe, nor an ascending resin flow from the posterior lobe to the median eminence and subependyma. Also failing to be noted were an ascending resin flow from the hypophysis to the hypothalamus and a descending resin flow from hypothalamus to the hypophysis.

Animals↗

PubMed1993

A hydrophilic resin-embedding method for light and electron microscopic detection of tissue anionic sites with cationic colloidal iron: as applied to mouse Paneth cells.

A cationic colloidal iron method was introduced for electron microscopic detection of anionic sites in hydrophilic resin-embedded specimens, and the method was applied to Paneth cells of the mouse jejunum. Mouse jejunal blocks were embedded in hydrophilic acrylic resin (LR White), cut into ultrathin sections, stained with the diluted cationic colloidal iron, and exposed to osmium vapor. The jejunal tissues, including the Paneth cells, embedded in hydrophilic resin were reactive to the fine cationic colloidal iron. At pH value 1.5, fine electron dense colloidal iron deposited along the rims of the secretory granules and the Golgi apparatus of the Paneth cell. Colloidal particles distributed on the osmiophilic reticular structures in the rim and in dot-like fashion lined the border between the granular core and rim. At pH value 4.0, ribosomes reacted to cationic colloidal iron particles in addition to the granular rims and Golgi apparatus. At pH 7.0, even the cores of the secretory granules were stained. Semi-thin sections prepared from the LR White-embedded specimens and stained at pH 1.5 with the diluted (1:3 in volume) cationic colloidal iron showed sufficient Prussian blue reaction for light microscopy in the rims of Paneth granules and mucus of goblet cells. This method is therefore useful for correlative light and electron microscopic detection of tissue anionic sites, including sulfate, carboxyl and phosphate groups, at various pH values.

Animals↗

PubMed1993

The occurrence of rat spinal cord neurons with strongly negative-charged surface coats.

Light microscopy of tissue sections stained with cationic iron colloid (pH 1.0-1.5) showed that the adult rat spinal cord contains some neurons which are provided with strongly negative-charged surface coats. These neurons are distributed preferentially in the posterior and intermediomedial columns of the grey matter. The present study thus supplements our previous study of the rat brain (MURAKAMI et al., 1993b), and proves that the neurons with strongly negative-charged surface coats occur widely in the central nervous system of the adult rat.

Animals↗

PubMed1993

Ectopic kidney in front of the right common iliac artery and its blood vascular supply--a case report.

A discoid-shaped ectopic kidney located in front of the right common iliac artery was observed in a 71-year-old Japanese man. The right kidney was normally positioned, but the left kidney was not observed in the normal position. The ureter of the ectopic kidney descended laterally to the left ductus deferens. The ectopic kidney received three arteries which arose from the anterior aspect of the abdominal aorta. Two of the arteries supplied the left half of the kidney. The other supplied the right half and gave off two branches to the adipose tissue around the right kidney; these branches meant that this artery belonged to the right side. Venous drainage from the kidney was handled by two veins. One collected venous radicles from the right half of the kidney and flowed into the inferior vena cava; this vein belonged to the right side. The other served the left half and joined with the left lumbar vein, which finally drained into the left common iliac vein; this vein was attributed to the left side. The present ectopic kidney had a left-side ureter, and vascular supply on both the right and left sides. This disunity or dissociation of laterality in the vessels and the ureter seemed to be strongly related to the location of this ectopic kidney in the median region.

Aged↗

PubMed1993

Flow-induced calcium transients and release of endothelium-derived relaxing factor in cultured vascular endothelial cells.

Cytoplasmic Ca2+ response to flow and its relation to the release of endothelium-derived relaxing factor (EDRF) by endothelial cells were studied in vitro. Intracellular Ca2+ concentration ([Ca2+]i) and EDRF were measured using Fura-2 and photometric fluorescence microscopy, and a bioassay method using a rabbit aortic ring, respectively. Cultured endothelial cells were exposed to flow in Hanks' balanced salt solution containing various concentrations of ATP in a specially designed apparatus. At ATP levels over 100 nM, the application of flow to cells led to an apparent increase in [Ca2+]i and when flow stopped [Ca2+]i returned to the resting level. When the flow rate was increased stepwise, [Ca2+]i increased flow-rate dependently at around 500 nM ATP. At a constant flow rate, endothelial cells were then exposed to the perfusate, the ATP concentration of which was increased stepwise, and the simultaneous changes in [Ca2+]i and release of EDRF were measured. Both [Ca2+]i and EDRF increased as ATP concentrations increased, and there was a proportional relationship between the two. The range of the ATP-induced increase in [Ca2+]i was similar to that of the flow-rate dependent changes observed at 500 nM ATP. These results suggest that vascular endothelial cells have a mechanism by which changes in flow rate or shear stress are recognized at an appropriate concentration of extracellular ATP and the information is converted into changes in [Ca2+]i. Moreover, the flow-induced changes in [Ca2+]i may be involved in the regulation of EDRF release by endothelial cells.

Adenosine Triphosphate↗

PubMed1993

[Influence of airway temperature and humidity of hyperventilation induced bronchoconstriction in rabbits].

It has been suggested that humidity and temperature of inspired air is important in determining the severity of hyperventilation induced bronchoconstriction (HIB). To investigate whether water loss or heat loss from airway plays more important role to induce HIB, we compared the effect of temperature and humidity of inspired air on HIB, in sensitized and non-sensitized rabbits. Inspired air containing 5% CO2 was conditioned to dry or humidified and to temperature of 9 degrees C or 25 degrees C during isocapnic hyperventilation. In sensitized rabbits, marked bronchoconstriction was observed when inspired air dry regardless of temperature. We conclude that 1) HIB is produced in sensitized rabbits and 2) humidity rather than temperature of inspired air is more important to induce HIB.

Animals↗

PubMed1992

Correlation of extracellular matrix components with the cytoarchitecture of mouse Peyer's patches.

The distribution patterns of extracellular matrix elements were determined to ascertain whether they play a role in the localization of lymphocytes in discrete T-cell, B-cell and dome antigen-processing domains within Peyer's patches. Antibodies against collagen types I, III and IV, laminin and fibronectin were applied to cryosections of mouse Peyer's patches and localized by direct or indirect immunoperoxidase methods. T-cell domains were identified with a monoclonal antibody against Thy-1.2. Labeled reticular fibers in distinctive patterns were more numerous in parafollicular and dome areas than within follicles. Germinal centers contained few such fibers. In parafollicular areas, fibers were oriented predominantly toward follicle domes; their distribution corresponded to T-cell zones and lymphocyte traffic areas, with their orientation being parallel to the migration pathways of lymphocytes from high endothelial venules to the antigen-processing domes. Subepithelial and subendothelial basal laminae were immunopositive for type-IV collagen, laminin and fibronectin. The dome subepithelial basal lamina had pore-like discontinuities through which lymphocytes migrated to and from the epithelium. The correspondence of the distribution patterns of extracellular matrix to specific functional domains of Peyer's patches suggests that this matrix provides a structural framework for lymphocyte migration and localization.

Animals↗

PubMed1992

Eucapnic hyperventilation-induced bronchoconstriction in rabbits.

We examined whether eucapnic hyperventilation with dry air produces the bronchoconstriction in anesthetized, non-sensitized rabbits and in ovalbumin sensitized rabbits. Eucapnic hyperventilation challenge with dry air containing 5% CO2 at room temperature was performed with 4 non-sensitized and 7 sensitized rabbits by mechanical ventilation for 15 min (120 breaths/min, 7 ml tidal volume/kg body weight). Total lung resistance (RL) and dynamic compliance (Cdyn) were measured before and 0, 5, 15, and 30 min after hyperventilation. In non-sensitized rabbits, RL and Cdyn did not change significantly. However, in sensitized rabbits, RL increased maximally by 48.9% +/- 9.0% at 5 min, and then decreased to the baseline level at 30 min after challenge. Cdyn decreased maximally by 12.5% +/- 3.5% at 15 min after challenge. These changes were significantly different from the baselines (p < 0.05). Furthermore, to investigate the role of histamine on hyperventilation-induced bronchoconstriction (HIB) in sensitized rabbits, we performed the hyperventilation challenges in 5 sensitized rabbits with the pretreatment of H1-receptor antagonist (chlorpheniramine, 1 mg/kg, i.v.) and found that the maximum increment of RL was suppressed to 24.2% +/- 7.4% of the control, which was significantly lower than the maximal RL in nontreated sensitized rabbits (p < 0.05). We concluded that HIB occurs only in sensitized rabbits and that histamine may play an important role in the development of HIB in sensitized rabbits.

Airway Resistance↗

PubMed1992

Incomplete vascular casting for a scanning electron microscope study of the microcirculatory patterns in the rat pancreas.

Scanning electron microscopy of resin casts prepared by incomplete arterial injections showed that in the rat pancreas, the casting medium fills blood capillaries in the endocrine islets more promptly than those in the exocrine lobules and secretory ducts. Furthermore, the exocrine lobules containing endocrine islets allowed a more rapid resin flow through the insulo-acinar portal route than those lobules lacking an islet. The secretory ducts were the last portions to be filled with resin. Since the resin medium used in this study was as viscous as blood and injected under a physiological pressure, the microcirculatory modes demonstrated by the present method suggest the physiological flow of blood in the rat pancreas.

Animals↗

PubMed1992

Reduction of corticosterone-induced muscle proteolysis and growth retardation by a combined treatment with insulin, testosterone and high-protein-high-fat diet in rats.

An experiment was conducted to clarify the combined effect of simultaneous administrations of insulin (Ins, 4 units/100 g body weight/day) and testosterone propionate (TP, 2 mg/100 g body weight/day) and feeding a high-protein-high-fat (HPHF) diet (50% protein, 36% fat) on corticosterone (CTC, 10 mg/100 g body weight/day)-induced muscle proteolysis or growth retardation in young growing male rats. After 6 days prefeeding of the standard (STD) diet (25% protein, 9% fat) and the HPHF diet, hormones were injected subcutaneously for 4 days. Urine was collected every day for the 4-day experimental period to measure N tau-methylhistidine excretions. The results were as follows. The growth was markedly inhibited and muscle proteolysis was accelerated by the CTC treatment. Feeding HPHF diet reduced CTC-induced muscle proteolysis and the growth retardation, and administrations of Ins and TP further reduced the proteolysis and the growth retardation. From these results, it is thought that administrations of Ins and TP and feeding HPHF diet minimize the muscle protein wasting by counteracting insulin resistance caused by CTC, and masking the CTC receptor.

Animals↗

PubMed1992

[Peripheral airway obstruction and treatment].

The effect of medication on peripheral airway obstruction was examined in cases of bronchial asthma. Subjects were 1) patients with exercise-induced asthma, 2) an animal model of hyperventilation-induced asthma and 3) patients with chronic asthma. Peripheral airway obstruction was induced in 30 of 51 patients with exercise-induced asthma. Induction of peripheral airway obstruction was protected significantly by procaterol. Cromoglycate was effective in 12 of 17 patients but ipratropium was not effective against induction of peripheral airway obstruction. In the animal model, humid air inhalation, procaterol and ipratropium completely prevented hyperventilation-induced bronchoconstriction, but cromoglycate caused only partial prevention. In cases of chronic asthma with peripheral airway obstruction, beclomethasone inhalation reduced the symptom rating rapidly, but no changes were observed in pulmonary function and threshold of airway responsiveness. Cromoglycate was started in patients with chronic asthma who had been treated with beclomethasone. After cromoglycate administration, therapeutic rating decreased, but increased again after 8 weeks of cromoglycate therapy. Peripheral airway obstruction induced by exercise or hyperventilation could be prevented by adequate premedication, but chronic peripheral airway obstruction was difficult to treat.

Administration, Inhalation↗

PubMed1991

Effect of extracellular ATP level on flow-induced Ca++ response in cultured vascular endothelial cells.

Cultured vascular endothelial cells loaded with the highly fluorescent Ca(++)-sensitive dye Fura-2 were exposed to the flow of a fluid containing various concentrations of ATP (0, 0.5, 1, 5 microM) in an apparatus designed on the basis of fluid dynamics, and simultaneous changes in intracellular free Ca++ concentration were monitored by photometric fluorescence microscopy. The flow rate of the perfusate was altered from 0 to 6.3 to 22.8 to 39.0 cm/sec, inducing shear stress on the cell surface of 0, 2.9, 10.4, and 17.9 dynes/cm2, respectively. Although no significant change in intracellular Ca++ level was observed at ATP levels below 100 nM, at an ATP level of 500 nM, the intracellular Ca++ level increased together with an increase in the flow rate of the perfusate. At this level of ATP, the intracellular Ca++ levels at flow rates of 0, 6.3, 22.8, and 39.0 cm/sec were 44.8 +/- 7.3, 60.3 +/- 10.7, 74.0 +/- 5.8 and 89.4 +/- 6.4 nM (mean +/- SD; n = 8), respectively. At ATP levels over 1 microM, the flow-rate dependency of Ca++ response became less clear than that observed at the ATP level of 500 nM. These Ca++ responses to changes in flow rate disappeared when extracellular Ca++ was chelated by adding 2 mM of EGTA to the perfusate. These results suggest that the vascular endothelial cell has a mechanism that elevates the intracellular Ca++ level in accord with the flow rate at appropriate ATP concentrations, and that changes in intracellular Ca++ level under this mechanism seem to be chiefly caused by the influx of extracellular Ca++ into cells.

Adenosine Triphosphate↗

PubMed1991

Organization of the reticular network of rabbit Peyer's patches.

The organization of the network of collagen fibers of rabbit Peyer's patches was examined by scanning electron microscopy (SEM) in alkali-water macerated tissues. The relationship between this network and the reticular cells within it was further studied by SEM of ultrasonicated tissues. Collagen fibrils (about 60 nm in diameter) formed collagen fibers or sheets. There were sheets of collagen fibrils with numerous pores beneath the patch dome epithelium. Within the patches, collagen fibers repeatedly divided and fused, forming the reticular network. The reticular network within the follicle was looser than within the dome, the corona, or the interfollicular area. The latter three compartments showed similar structures and consisted of numerous intercommunicating small subcompartments. Reticular cells were in contact with groups of free cells lodged in these subcompartments within the reticular network. Reticular cell processes with numerous fenestrations embraced not only collage fibers forming the reticular network, but also sheaths of collagen fibers of blood and lymphatic vessels. Sheaths of collagen fibers of high endothelial venules and lymphatic vessels were also fenestrated, indicating the sites through which lymphocytes and other free cells migrate. These results indicate that the reticular network of Peyer's patches is organized so as to facilitate migration and lodging of free cells and thus facilitate antigen-to-cell and cell-to-cell interactions during an immune response. The naked areas on the collagen fibers seem to provide a scaffolding for free cells during their migration.

Animals↗

PubMed1991

Microvascular architecture of rat nasal associated lymphoid tissue.

The blood vascular architecture of the rat nasal associated lymphoid tissue (NALT) was studied by scanning electron microscopy of corrosion casts. To examine the correlation of the vasculature with the distribution of lymphocyte subsets, the NALT was also studied by light microscopy of immuno-stained samples. The NALT was supplied by a branch of the inferior nasal artery which arose from the sphenopalatine artery. This branch reached the bottom of the NALT and ramified arterioles to the follicles and the parafollicular regions. These arterioles ascended toward the subepithelial region, giving off capillaries en route to form a coarse plexus within the follicles and the parafollicular regions. The arterioles reached the subepithelial region and formed a subepithelial capillary network consisting of a single layer of flat meshwork. The follicular, parafollicular and subepithelial capillaries anastomosed one another. The capillaries in each region were gathered into collecting venules, which in turn drained into high endothelial venules (HEVs) in the parafollicular region. The HEVs ran through the parafollicular regions around the follicular perimeters, and flowed into ordinary veins to leave the NALT. Lymphocytes labeled with an anti-T cell antibody were mainly distributed in the parafollicular regions, where HEVs were situated. B cells were mostly observed in the follicular and dome areas. The microvascular structure and its correlation with lymphocyte subset domains in the NALT were essentially similar to those in other mucosa associated lymphoid tissues (MALTs) such as tonsils and Peyer's patches.

Animals↗

PubMed1991

[Examination of the inhibitor to factor VIII in non-haemophilic patient].

We examined an inhibitor to factor VIII in non-haemophilic patient who had been developed widely spread ecchymosis and intramuscular bleeding. He had no previous personal or family history of abnormal bleeding tendency. His laboratory data was all normal except examination for blood coagulation. Coagulation studies showed prolonged activated partial thromboplastin time (48 sec) and decreased factor VIII activity (8%). The activity of the inhibitor to factor VIII was demonstrated to be 4.0 Bethesda unit. By the studies of dilution and time response curve, this inhibitor was found to inhibit up to 90% of factor VIII activity but not 100%. This inhibitor was shown to be IgG by protein-A affinity chromatography. In addition, bleeding time was prolonged in the patient. The value of von Willebrand factor antigen was 200%, but that of Ristocetin cofactor was 93%. Since the gel filtration analysis indicated that this inhibitor also suppressed Ristocetin cofactor activity, the relatively low value of Ristocetin cofactor might occur through the action of the inhibitor. These data suggest that patient's inhibitor react to factor VIII high molecular subunit.

Blood Coagulation Disorders↗

PubMed1990

[Fluid shear stress effects on intracellular calcium concentrations in cultured vascular endothelial cells].

Vascular endothelial cells are known to modulate their functions in response not only to humoral stimuli but also to such physical stimuli as fluid shear stress generated by blood flow. However, the mechanisms by which the hemodynamic force acts on endothelial cells are not yet well understood. We have studied how endothelial cells recognize the shear stress and mediate it to intracellular organelles. Cultured monolayers of bovine aortic endothelial cells loaded with the highly fluorescent Ca+(+)-sensitive dye Fura 2 were exposed to different levels of fluid shear stress in a specially designed flow chamber and simultaneous changes in intracellular-free Ca+(+) concentration were measured using photometric fluorescence microscopy. Application of shear stress to cells by fluid perfusion led to an immediate several-fold increase in Ca+(+) concentration within 1 min, followed by a rapid decline, and finally a plateau somewhat higher than control levels during the entire period of the stress application. The early part of the response, but no plateau, was observed even in Ca+(+)-free medium added with 2 mM EDTA, and in the presence of calcium antagonists (e.g. 2 x 10(-5) M nicardipine). Thus, endothelial cells may have a flow-sensing property which recognize the shear stress on the membrane as a stimulus and mediates the signal to increase intracellular free Ca(+)+ which is a major component of the internal signalling system of the cell.

Animals↗