Biomedical subjects

K Hatakeyama

Publications and source records attributed to K Hatakeyama.

At least 91 records · Page 5Linked to original sources

PubMed2001

Helical computer assisted tomography in pulmonary hypertension complicating left-to-right shunts--correlation with pulmonary hemodynamics.

The present study analyzed the helical computer-assisted tomography (CAT) findings in 30 patients with pulmonary hypertension (PH) associated with left-to-right shunts; specifically, ventricular septal defect, 23; atrioventricular septal defect, 6; patent ductus arteriosus, 1. Eight patients had 21 trisomy. Age ranged from 1 to 18 (mean, 4.1) months, and body weight ranged from 2.6 to 10.7 (mean, 4.9) kg. In all patients, the chest CAT revealed patchy areas of high and low attenuation (mosaic pattern) and regional atelectasis in the lung fields. The volume of low attenuated lesions and of atelectasis, and the total lung volume were derived from integration of areas measured on the CAT image. The ratios of low attenuated lesion/total lung volume (Lo), volume of atelectasis/ total lung volume (Ate) and low attenuated lesion and volume of atelectasis/total lung volume (Lo&Ate) were compared with hemodynamic parameters measured at cardiac catheterization. The pulmonary to systemic resistance ratio correlated with Lo (r=0.61, p<0.01) and Lo&Ate (r=0.69, p<0.01), whereas the pulmonary vascular resistance correlated with Ate (r=0.53, p<0.01). Lo, Ate and Lo&Ate in the chest CAT are reliable parameters that can be used to estimate pulmonary vascular resistance in patients with PH associated with left-to-right shunts.

Cardiac Catheterization↗

PubMed2001

Acute necrotizing eosinophilic myocarditis successfully treated by high dose methylprednisolone.

Acute necrotizing eosinophilic myocarditis is the most severe form of eosinophilic myocarditis, or hypersensitivity myocarditis, and is characterized by rapidly progressive congestive heart failure followed by fulminant clinical deterioration that is nearly always fatal. A 55-year-old previously healthy patient with acute necrotizing eosinophilic myocarditis was diagnosed by early myocardial biopsy and successfully treated with corticosteroids. Throughout his hospitalization, the eosinophil count in the peripheral blood remained normal (56-201/mm3). Early stage corticosteroid therapy can have dramatic effects in acute necrotizing eosinophilic myocarditis and early diagnosis by endomyocardial biopsy is recommended.

Acute Disease↗

PubMed2001

Closed-loop control using a stretch sensor for restoration of standing with functional electrical stimulation in complete paraplegia.

A closed-loop control system for standing with functional electrical stimulation (FES) using percutaneous intramuscular electrodes in complete paraplegia is described. The system consisted of ultrafine percutaneous intramuscular electrodes, a 32-channel stimulator and a stretch sensor with active current control to detect knee buckling. The closed-loop control system was applied in a T8 completely paraplegic patient. Compared to the stretch sensor with a wide use flexible goniometer for direct current control during standing, the stretch sensor was superior to the flexible goniometer in both ease of use and response. The average time delay from the start of knee buckling until the sensor turned on was 0.56+/-0.19 seconds (Mean+/-S.D.) in the goniometer and 0.21+/-0.06 seconds in the stretch sensor. The average time delay from the start of knee buckling until the recovery from knee buckling was 1.01+/-0.05 seconds in the goniometer and 0.78+/-0.06 seconds in the stretch sensor. The continuous standing ability of the patient increased from 12 minutes with open-loop stimulation to 30 minutes with the closed-loop control. No complications such as falling occurred during clinical use. This system prevented falling due to knee buckling during standing and prolonged upright activities in complete paraplegics.

Adult↗

PubMed2001

Immunolocalization of aquaporin-8 in rat digestive organs and testis.

Expression of aquaporin-8 mRNA has previously been shown in hepatocytes, pancreatic acinar cells, colon epithelial cells and seminiferous tubules of the testis in the rat by in situ hybridization technique. However, immunolocalization of this water channel has not yet been demonstrated. In the present study, the localization of immunoreactive aquaporin-8 and expression of the mRNA were examined in rat organs (cerebrum, cerebellum, eye, salivary gland, heart, lung, liver, pancreas, esophagus, stomach, jejunum, ileum, colon, testis, ovary, kidney, spleen and lymphnode) by immunohistochemistry using an antibody against aquaporin-8 and ribonuclease protection assay. Aquaporin-8 was distinctly immunolocalized on the apical membranes of pancreatic acinar cells and mucosal epithelium of the colon and jejunum. In the liver, the bile canalicular membrane of hepatocytes was immunostained. In the testis, immunoreactive aquaporin-8 was demonstrated on the luminal side of the seminiferous tubules. At high magnification, the peroxidase reaction products appeared on the ramified cytoplasmic membrane of Sertoli cells surrounding the residual bodies or spermatogenic cells. Specificity of the antibody was verified by Western blot analysis showing a minor approximately 28 kDa band (deduced deglycosylated form of aquaporin-8) and a major approximately 30 kDa band (glycosylated form) in these organs. The intensity of aquaporin-8 immunoreactivity was approximately comparable to that of aquaporin-8 mRNA expression in the liver, pancreas, colon, jejunum and testis. The aquaporin-8 mRNA expression in the hepatocytes was presumed to be closely associated with the structure of bile canaliculi since the message was detected in hepatocytes immediately after isolation from the liver but not in cells following cultivation for three days. The localization of immunoreactive aquaporin-8 indicated functions for this water channel in the secretion of bile and pancreatic juice, and the secretion or absorption of water in the colon and jejunum, and the maturation or liberation of spermatogenic cells in the testis.

Animals↗

PubMed2001

Role of heme oxygenase-1 and Kupffer cells in the production of bilirubin in the rat liver.

Heme oxygenase (HO)-1, the heme-degrading enzyme in macrophages, plays a key role in bilirubin metabolism. HO-1 is expressed in various tissue macrophages, especially Kupffer cells. This study aimed to examine the roles of macrophages and HO-1 in the modulation of heme catabolism in rat livers. Rats treated with or without liposome-encapsulated dichloromethylene diphosphonate, a macrophage-depleting reagent, were administered with heat-denatured red blood cells (h-RBC), and the time course of the biliary output of bilirubin and the expressions of HO-1 mRNA and protein were monitored. Immunohistochemistry in the control rat liver revealed that Kupffer cells constitute a major cellular component expressing HO-1, while hepatocytes exhibited little expression. The levels of HO-1 expression in Kupffer cells were elevated immediately after injection of h-RBC. In Kupffer cell-depleted livers, however, HO-1-expressing cells were not detected even after h-RBC administration. HO-1 mRNA levels were elevated at 2 h after administration of h-RBC in control rat livers, while they were very low in Kupffer cell-depleted rat livers. The control and Kupffer cell-depleted groups exhibited distinct time courses of biliary bilirubin excretion. In the untreated control rats, total bilirubin excretion increased about two-fold at 5 h after h-RBC administration. In contrast, the Kupffer cell-depleting treatment decreased the level of bilirubin production; administration of h-RBC to Kupffer cell-depleted rats did not accelerate the generation of bilirubin. These results suggest that Kupffer cells serve both as a sensor for scenesent RBC clearance and an effector that upregulates heme-degrading capacity and bilirubin production.

Animals↗

PubMed2001

Morphological characteristics of Schwann cells in the islets of Langerhans of the murine pancreas.

The present study demonstrated the three-dimensional architecture of peri-insular nerve plexuses in the murine pancreas by the combined use of light microscopy of S-100 immunostained sections, transmission electron microscopy (TEM) of thin sections, and scanning electron microscopy (SEM) of KOH digested tissues. By light microscopy of thin sections immunostained with anti-S-100 antibody, Schwann cells were often found on the margin of the islets as if delimiting the islet and exocrine parenchyma. In thick sections, Schwann cells of the islet connected their thin and slender processes with each other to form a delicate network on the surface of the islet. By TEM, Schwann cells were observed as an attenuated sheet that invested the surface of the islet. Axon terminals were usually found on the outer surface of these membranous Schwann cells. SEM of KOH digested tissues revealed that nerves reaching the islet spread on the insular surface. Schwann cells in this portion extended their thin membranous processes, which directly covered the basal part of several endocrine cells as a whole. Numerous axons with varicosities were usually found on the surface of these membranous Schwann cells, but sometimes crept beneath them. These findings indicate that "the interstitial cells" described by light microscopists are peculiar-shaped Schwann cells present in the islets. The functional significance of the rich innervation of the islets is also briefly discussed in the present study.

Animals↗

PubMed2001

Immunolocalization of aquaporin-9 in rat hepatocytes and Leydig cells.

The aquaporin (AQP)-9 gene was recently isolated from human and rat liver cDNA libraries as a member of the water channel family for water and neutral solutes. Although the expression of AQP9 mRNA has been demonstrated in several organs including the liver and testis by Northern blot analysis, the cellular and subcellular localization of the AQP9 protein remains unclear. In the present light and electron microscopic immunohistochemical study, the localization of the AQP9 immunoreactivity was examined in fifteen kinds of rat organs using an antibody against rat AQP9 synthetic peptide. The antibody immunostained a major band of approximately 33 kDa in the liver by Western blot analysis. Immunoreactivity for AQP9 was found exclusively in the liver and testis among the organs examined. In the liver, positive staining appeared selectively along the space of Disse. Immunoelectron microscopy confirmed the localization of AQP9 on the surface of hepatocyte microvilli facing the space of Disse. In the testis, the plasma membrane of Leydig cells located between seminiferous tubules was conspicuously immunoreactive to the antibody. Intense mRNA expression was detected in the liver and testis but not in other organs by ribonuclease protection assay. These findings suggest a specific role for AQP9 in the transport of water and non-charged solutes in hepatocytes and Leydig cells.

Animals↗

PubMed2001

[Surgery and the Japan Surgical Society at the beginning of the 21st century].

Numerous advances in medicine occurred during the latter half of the 20th century, and progress will accelerate in the 21st century. In particular, research in molecular biology has made significant advances, and it was reported that the human genome was almost completely deciphered in June 2000. This will contribute greatly to genetic research in malignant diseases. The development of regenerative medicine, such as cell transplantation using differentiated embryonic or mesenchymal stem cell, will have a significant effect on the field of surgery. The Japan Surgical Society must apply the new knowledge being made available to realize the concept of integrative medicine, in which surgery will play a major role. Substantial changes in postgraduate and continuing education and training of surgeons may be necessary. Other topics for discussion include risk management in the case of surgical accidents and medical ethics based on the Declaration of Helsinki.

Education, Medical, Continuing↗

PubMed2001