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Biomedical subjects

A Okada

Publications and source records attributed to A Okada.

At least 361 records · Page 20Linked to original sources
PubMed1988

Developmental changes in density and distribution of serotoninergic fibers in the chick spinal cord.

Developmental changes of serotoninergic innervation in the chick spinal cord (third lumbosacral segment) were examined with an immunohistochemical technique using an antiserum to serotonin. In the 1-day-old hatched chick, serotoninergic fibers were located in laminae I, II, VII, IX, and X. A large number of serotonin-positive fibers and terminals were found around somal profiles of large neurons and in the neuropil of the medial and lateral parts of the lateral motor column (LMC). In the 1-week-old chick, the density of serotoninergic fibers was greatly increased in the posterior columns, and serotoninergic fibers were most densely aggregated in the dorsolateral part of the LMC. In the 2-week-old chick, a considerable decrease in the density of serotoninergic fibers was observed in the lateral funiculus and the gray matter (laminae I, II, VII, IX, and X). In the LMC, serotonin-positive fibers and terminals were largely absent from the neuropil, but were found preferentially around the somal profiles of large neurons. Between 1 and 2 weeks after hatching the density of varicosities and terminals in the neuropil of the dorsolateral and medial parts of the LMC decreased by 33% and 56%, respectively. In the 3-month-old chick, the density of serotoninergic fibers in laminae I, II, V, VII, and X had increased compared to younger ages. Serotonin-positive fibers were not evenly distributed in the LMC of the adult chicken; rather, they were densely aggregated around the soma and proximal dendrites of motoneurons in the dorsolateral LMC. Many neuronal soma in the medial and intermediate regions of the LMC lacked serotoninergic fibers.

Animals↗
PubMed1988

Sequence and organization of the human T cell delta chain gene.

A novel human T cell receptor (TcR) gene, located 85 kbp upstream to the C alpha coding regions, was isolated using human genomic clones to identify cDNA homologous to messages encoded by this region. The deduced protein sequence of this gene is highly homologous to that of the newly identified constant region found in the murine TcR alpha chain locus. This gene undergoes rearrangements and is expressed at the RNA level in human thymocytes, peripheral T cells and several leukemic T cell lines which have been shown to express the surface gamma-delta heterodimer, suggesting that this gene encodes the human T cell delta chain.

Amino Acid Sequence↗
PubMed1988

Comparison of phospholipid synthesis in rat salivary glands: properties of 1-acylglycerophosphorylcholine and 1-acylglycerophosphate acyltransferase systems in microsomes.

1. 1-Acyl-sn-glycerol-3-phosphorylcholine and 1-acyl-sn-glycerol-3-phosphate acyltransferase activities were characterized in rat salivary gland microsomes. 2. The acyl-CoA selectivities between these two kinds of lysophospholipid acyltransferase activities were very different. 3. When the three major glands were compared (parotid, submandibular, sublingual), they showed their own particular acyltransferase activity, but they had very similar in acyl-CoA selectivity. 4. Those observations were also compared in rat liver microsomes.

1-Acylglycerol-3-Phosphate O-Acyltransferase↗
PubMed1988

[Effects of local vibration exposure on whole blood viscosity in rats].

To investigate the relationship between vibration hazards and blood viscosity, vibration exposure experiments were conducted. The rat's hind limbs were continuously exposed to local vibration (60 Hz, 5 G) for 4 h. The exposed group showed a slightly lower blood viscosity and plasma fibrinogen in the blood obtained immediately after exposure when compared with the control group. However, in the blood obtained 18 h after exposure, there was no significant difference in the levels of whole blood viscosity and plasma fibrinogen between the exposed group and the control group. Hematocrit was not affected by this exposure. These results indicate that the decrease in the levels of whole blood viscosity induced by local vibration exposure is transient and that some relationship exists between changes of whole blood viscosity and those of plasma fibrinogen.

Animals↗
PubMed1988

Effects of low- and high-frequency local vibration on the occurrence of intimal thickening of the peripheral arteries of rats.

Rats were exposed to local vibration in a study of the differences in the effects between low and high frequencies of vibration on the vessel wall of peripheral arteries. The vibration was delivered at frequencies of 30 and 480 Hz under a constant acceleration of 5g. The duration of the vibration exposure was 30 d. The changes in the arteries were studied pathohistologically and hematologically. Three of the five rats exposed to 30 Hz and three of the five rats exposed to 480 Hz showed disruption of the internal elastic lamina. The disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibers. The vascular changes observed after vibration exposure could not be explained by changes in plasma lipid concentrations. These results suggest that not only low frequencies of vibration, but also high frequencies have harmful effects on the intima of small arteries.

Animals↗
PubMed1988

Protection against the lethal effects of whole body vibration by the alpha-adrenergic system in rat.

To investigate the protective mechanism against the lethal effect of whole body vibration, the phentolamine (1 mg/kg) pretreated rats were exposed to whole body vibration with a frequency of 20 Hz under an acceleration of 5 G at 24 +/- 2 degrees C and 5 +/- 1 degrees C. Five of 9 rats pretreated with phentolamine died from the exposure to whole body vibration within one hour at 24 +/- 2 degrees C. In these rats, marked infrapleural hemorrhage, dilatation of alveolar capillary vessels, and intraalveolar hemorrhage and edema were observed. However, all of the 10 rats pretreated with saline survived through the one hour exposure to the same vibration, and showed only slight histological changes in the lung. On the other hand, no rats pretreated with saline or phentolamine died from the exposure to whole body vibration within one hour at 5 +/- 1 degrees C. These results suggest that the alpha-adrenergic system and cold have a role of protection against the lethal effects of whole body vibration.

Animals↗
PubMed1988

[Long term prognosis after massive small bowel resection in children].

Eight survivors after massive small bowel resection were reviewed for a period of 2 to 19 years to assess the long term prognosis of patients. The primary diseases of short bowel syndrome were congenital intestinal atresia (6) and midgut volvulus (2). The length of the residual small intestine ranged between 27 and 75 cm and ileocecal valve was also resected in 3 cases. All cases had been already weaned from parenteral nutrition and six children tolerate normal meals and two have still enteral formula at home now. Near normal somatic growth was achieved in cases which received intensive nutritional supports after operation. The D-Xylose absorption test revealed gradual improvement except one with the shortest intestine (27 cm) and fat absorption was disturbed in patients who had less than 45 cm residual intestine. Late metabolic complications, such as renal calculus, cholelithiasis and pathologic fractures were encountered in three cases.

Child, Preschool↗
PubMed1988

Histopathologic studies of congenital dilatation of the bile duct as related to an anomalous junction of the pancreaticobiliary ductal system: clinical and experimental studies.

Clinical and experimental studies of congenital dilatation of the bile duct as related to an anomalous junction of the pancreaticobiliary ductal system were performed. Epithelial hyperplasia accompanied by round cell infiltration and increased thickness of the wall with fibrosis was observed histologically in the resected bile ducts of all 40 patients. Twenty-two of 26 patients (86.4%) who had bouts of abdominal pain showed that epithelial hyperplasia with round cell infiltration is dominant (glandular type), and 11 of 15 cases (73.7%) with persistent jaundice showed that thickness of the wall with fibrosis is dominant (fibrotic type). Amylase activities in bile of glandular-type cases obtained from the common bile duct intraoperatively were significantly greater than those of fibrotic-type cases (p less than 0.01). The common bile ducts of the canine model, in which whole pancreatic juice passed in the bile duct, dilated cylindrically 3.28 +/- 2.48 times in diameter after 24 to 41 days and histologically showed epithelial hyperplasia with round cell infiltration of the glandular type. These findings suggest that an anomalous junction of the pancreaticobiliary ductal system and the reflux of pancreatic juice into the bile duct affect not only clinical manifestations but also pathologic changes, especially of the glandular type, in patients with congenital dilatation of the bile duct.

Adult↗
PubMed1987

Conformations of yeast alpha-mating factor and analog peptides as bound to phospholipid bilayer. Correlation of membrane-bound conformation with physiological activity.

The transferred nuclear Overhauser effects of yeast alpha-mating factor [(1-13)peptide] in the presence of various spin-labeled phosphatidylcholines in small unilamellar vesicles of perdeuterated phosphatidylcholine have been analyzed. From the analysis of the quenching effect by spin-labels, the depth of amino acid side chains of the mating factor in phospholipid bilayer has been elucidated. The Leu4 and Leu6 residues are buried deeply in the apolar region of the phospholipid bilayer while the hydrophilic residues such as Gln5 and Lys7 are in the shallow region of the bilayer. The interaction of the side chains of Trp1 and Trp3 residues of alpha-mating factor with the hydrophobic interior of the bilayer contributes to the binding of this peptide with the phosphatidylcholine bilayer. The conformation of des-Trp1-alpha-mating-factor [(2-13)peptide] in the membrane-bound state has been found to be similar to that of (1-13)peptide from the analysis of transferred nuclear Overhauser effects in the presence of mixed vesicles of perdeuterated phosphatidylcholine and perdeuterated phosphatidylserine. The incorporation of this acidic phospholipid in the vesicle remarkably enhances the binding of (1-13)peptide and analog peptides. However, such modifications that weaken the interaction with phospholipid bilayer (deletion of Trp1 and substitution of Trp3 by Gly or Ala) appreciably lower the physiological activity. Transferred nuclear Overhauser effect analyses have also been made of [DHis2]peptide, [DLeu6]peptide and [DLys7]peptide in the presence of the vesicles of perdeuterated phosphatidylcholine. The main-chain conformations of these three analogs in the membrane-bound state have been found to be similar to that of (1-13)peptide, although the side-chain conformations of the D-amino acid residues are naturally different from those of the L-amino acid ones. Thus, the physiological activities of the (1-13)peptide and a variety of analog peptides are found to correlate with the affinities to the phosphatidylcholine/phosphatidylserine membrane and with the molecular conformations in the membrane-bound state.

Circular Dichroism↗
PubMed1987

Comparison of membrane phospholipid and its fatty acid compositions in developing rat salivary glands.

1. Membrane phospholipid and its fatty acid compositions have been analyzed in 3- and 9-week-old rat salivary glands. 2. When compared between the three major glands (parotid, submandibular, sublingual) in adult rats, phospholipid compositions were similar, but for their fatty acid, characteristic properties from each phospholipid were shown. 3. Alterations in their compositions were also observed during development of the salivary glands.

Aging↗
PubMed1987

Changes in proton T1 in dog brains due to the administration of haloperidol.

Changes in proton T1 in dog brains due to the administration of haloperidol were determined by the intravenous administration of a single dose of 20 mg of haloperidol to mongrel dogs. The MRI used was the Aberdeen type with the static magnetic field of 0.1 T. A coil made exclusively for these animals (bore diameter 120 mm) was used. There was a significant increase in the T1 value in the striate body 30 minutes and more (within two hours) after the administration of haloperidol. Subtraction images were also obtained by subtracting the image of the pre-treatment (control) T1 values from the image of the post-treatment values (2 hours after the injection). The subtraction images also revealed increases in the T1 values of the striate body.

Animals↗
PubMed1987

Occurrence of intimal thickening of the peripheral arteries in response to local vibration.

Experiments were performed to elucidate a possible mechanism for the peripheral circulatory disturbance caused by vibration. Rats were exposed to local vibration (60 Hz, 5 G) on their hind legs for four hours a day for 30 days or 90 days. With exposure for 30 days the small arteries at the exposed site did not change. With exposure for 90 days, however, disruption of the internal elastic lamina was observed in the small arteries. This disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibres. The fibrocellular thickening of the intima was further augmented, and in addition a complete stenosis of the lumen of the small arteries was observed. Electron micrography showed that the fibrocellular thickening of the intima consisted of a proliferation of arterial smooth muscle cells and numerous collagen and elastic fibres. These alterations were not observed in the arteries of the controls. The thickness of the media did not differ between the control and exposed groups or in animals with different durations of exposure. Concerning plasma total cholesterol, HDL-cholesterol, and lipoperoxide, there were no significant differences between the control and exposed groups after either 30 or 90 days, but the whole blood viscosity was significantly increased by day 90. This finding may be related to the intimal thickening.

Animals↗