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A Ohtsuka

Publications and source records attributed to A Ohtsuka.

14 recordsLinked to original sources
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↗
PubMed1990

[Bronchoconstriction in isocapnic hyperventilation-induced asthma].

It is well known that some asthmatic patients develop bronchoconstriction after exercise challenge (exercise-induced asthma, EIA). Recently, it has been pointed out that isocapnic hyperventilation also induces similar bronchoconstriction (hyperventilation-induced asthma, HIA) in the same asthmatic subjects. However, the mechanism of HIA has not yet been determined. In the present study, we performed exercise and hyperventilation challenge in the same patients and pulmonary function data and neutrophil chemotactic factor (NCF) in peripheral blood were examined before and after both challenges. Twelve asthmatic patients with normal pulmonary function data on testing days were subjected to exercise test on a bicycle ergometer and then isocapnic hyperventilation tests in subsequent days. Subjects breathed dry air from the cylinder. Isocapnic hyperventilation was performed by monitoring minute ventilation and each patient followed the same minute ventilation exercise. The reduction of FEV1.0 and time course of airway obstruction were almost the same after exercise and hyperventilation testing. All patients who developed EIA also developed HIA and other patients did not develop both EIA and HIA. Changes of Rrs, V50 and V25 and their time course after each test were also similar in EIA(+) and HIA(+), and in EIA(-) and HIA(-). NCF increased significantly after both challenges in EIA(+) and HIA(+) patient, although increment of NCF was much less these the increases of HIA(+). These data may suggest that the development of bronchoconstriction was compatible after exercise and hyperventilation in each asthmatic patient, however, the mechanism of HIA may differ from EIA, although NCF slightly but significantly increased in HIA, suggesting the possible role of a chemical mediator.

Adolescent↗