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Biomedical subjects

H Mayahara

Publications and source records attributed to H Mayahara.

At least 19 recordsLinked to original sources
PubMed2005

Multiple pancreatic metastases from clear cell renal carcinoma: diagnosis with chemical shift magnetic resonance imaging before surgery.

We present a case in which multiple pancreatic tumours were diagnosed as metastatic clear cell renal carcinomas with chemical shift MRI (CSI) before surgery. Radiologists may be unable to recognize the loss of intensity on CSI macroscopically. We believe that it is useful to make subtraction images and calculate signal intensity on CSI, even if the lesions are multiple metastatic tumours.

Carcinoma, Renal Cell↗
PubMed2001

Pilot study of local radiotherapy for portal vein tumor thrombus in patients with unresectable hepatocellular carcinoma.

BACKGROUND: Patients suffering from hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT) generally have a poor prognosis. We therefore conducted a prospective pilot trial of combined transcatheter arterial chemoembolization (TACE) and local radiotherapy (RT) for PVTT in unresectable HCC. The aim of the study was to investigate the efficacy and toxicity of this preliminary trial regime and to explore RT guidelines for cirrhosis. METHODS: Eight patients with unresectable HCC accompanied by first branch PVTT were entered into the study from February 1998 to December 1999. TACE was performed using Lipiodol, epirubicin hydrochloride and mytomycin followed by gelatin sponge cubes. RT was started 10-14 days following TACE. A total delivered dose of 60 Gy was given as daily 2 Gy fractions, with the clinical target volume defined as PVTT only. We observed a relationship between deterioration of liver function and the percent volume of the total liver receiving a dose exceeding 30 Gy (V30). RESULTS: An objective response was observed in three of the eight patients. However, on follow-up angiograms the protrusion of PVTT into the main portal trunk was decreased in all cases. Deterioration of liver function was observed in all patients with V30 >40%. CONCLUSION: It is possible that this combined therapy prevents PVTT from spreading to the main trunk and that indicates a further benefit of TACE. Our results indicate that V30 constitutes a predictive test for the development of liver failure. More detailed evaluations of liver function and determination of the safe irradiation volume are necessary.

Aged↗
PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats--overview of the studies.

The National Institute of Health Sciences and 28 member companies of the Japan Pharmaceutical Manufacturers Association (JPMA) have conducted a validation study intended to examine whether or not lesions in the male reproductive organs noted in 4-week treatment studies can also be detected after 2-week treatment. In this study, lesions in the male reproductive organs after 2-week treatment were, therefore, compared with those after 4-week treatment. A total of 24 test substances was evaluated, these being nucleic acid modulators, cell division inhibitors, central hormonal modulators, hormonal drugs and their antagonists, other drugs and general chemicals. Among these substances, theophylline did not cause any appreciable lesions in the male reproductive organs even after 4-week treatment in the preliminary studies. With busulfan, data reported in the literature was not reproduced in the preliminary study and all animals died. Therefore, detailed examinations were not conducted for busulfan and theophylline. The remaining 22 test substances, when given to animals for 2 weeks at doses equal to or higher than for 4-week treatment, caused lesions similar to those noted after 4 weeks. It is evident from these findings that effects of pharmaceuticals on the male reproductive organs can be detected in most cases with 2-week treatment.

Animals↗
PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 24). Testicular toxicity of boric acid after 2- and 4-week administration periods.

To assess whether or not male reproductive toxicity can be evaluated in a 2-week administration study, boric acid was administered daily by oral gavage to male Jcl:Wistar rats at dosage levels of 0, 300 and 500 mg/kg for 2 and 4 weeks, and the results obtained with the two different treatment schedules were compared. After a 2-week administration, decreased testis weights were observed in the 500 mg/kg group. Histopathologically, exfoliation of round spermatids, retention of step 19 spermatids and increased numbers of residual body-like structures in the seminiferous tubules and cell debris in the cranial epididymal ducts were observed in the 300 and 500 mg/kg groups. Distorted cytoplasmic lobes of step 19 spermatids, debris in the seminiferous tubules and focal atrophy of the seminiferous tubules with multinucleated giant cells formation and necrosis of spermatocytes were also observed in the 500 mg/kg group. After a 4-week administration, testis and epididymis weights were decreased in the 300 and 500 mg/kg groups. Histopathological changes in the 300 mg/kg group were similar to those found in the 300 and 500 mg/kg groups after a 2-week administration. Diffuse atrophy of the seminiferous tubules was additionally observed in the 500 mg/kg group. These results suggest that 2 weeks is a sufficient treatment period for the detection of the testicular toxicity caused by boric acid.

Administration, Oral↗
PubMed1999

Systemic injection of FGF-2 stimulates endocortical bone modelling in SAMP6, a murine model of low turnover osteopenia.

The effects of systemically administered fibroblast growth factor-2 (FGF-2) at doses of 0.1 and 0.3 mg/kg/day for 7 days were investigated 5-week-old male SAMP6 mice, a model of low turnover osteopenia. The bone histomorphometry in the distal epiphyseal growth plate of the femur showed that 0.3 mg/kg/day of FGF-2 decreased the longitudinal growth rate and cartilage cell production rate and increased the growth plate width. Growth plate chondrocytes showed the features of defective endochondral ossification at the same dosage level. In the distal one third of the femur, the marrow trabecular area, endocortical mineral apposition rate and/or bone formation rate were increased in both the SAMP6 mice given 0.1 and 0.3 mg of FGF-2/kg/day. In this region, the endocortical osteoblasts were hypertrophied with some layers of overlying proliferated fibroblastic mesenchymal cells. The presence of small foci of bone formation within the layers of these mesenchymal cells indicates their osteogenic potential. On the other hand, the periosteal bone formation rate in the mid-shaft of the femur was depressed in the 0.3 mg/kg/day group. These results suggest that systemically administered FGF-2 may have the possibility to increase the peak bone mass in SAMP6 by stimulating the osteoprogenitor cells to proliferate and differentiate into osteoblasts and enhancing endocortical bone modelling. The higher dose of FGF-2, however, inhibited both endochondral and periosteal bone formation.

Animals↗
PubMed1995

Effects of basic fibroblast growth factor (bFGF) on bone formation in growing rats.

The effects of basic fibroblasts growth factor (bFGF) administered intravenously at dosages of 0.1 and 0.3 mg/kg per day for 7 days to growing rats are reported. Static and dynamic histomorphometry techniques were applied to the microradiographs and undecalcified ground sections of the proximal tibiae and tibial shafts. The bone histomorphometric analyses in the proximal tibia revealed that 0.1 mg/kg per day of bFGF increased longitudinal growth rate, cartilage cell production rate, and metaphyseal bone area. In the tibial shaft, the endocortical mineral apposition and bone formation rates, total bone area, total osteoid area, and medullary bone area were increased, but the periosteal mineral apposition and bone formation rates were depressed. Two weeks after the cessation of treatment, the increased osteoid bone on the endocortical surface and in the marrow cavity was completely calcified, and the total mineralized area in the tibial shaft was significantly increased. The rats given 0.3 mg of bFGF/kg per day showed retarded weight gain, defective calcification at the growth plate metaphyseal junction, and on the endocortical surface. The growth plate width was increased, and the longitudinal growth rate, cartilage cell production rate, endocortical labeled surface, and bone formation rate were decreased. Two weeks after the cessation of treatment, these changes were almost reversed, and the longitudinal growth rate and cartilage cell production rate were increased as rebound phenomena. These results suggest that a low dose (0.1 mg/kg per day) of bFGF stimulates endosteal and endochondral bone formation and depresses periosteal bone formation in growing rats.

Analysis of Variance↗
PubMed1993

In vivo stimulation of endosteal bone formation by basic fibroblast growth factor in rats.

Intravenous administration of human basic fibroblast growth factor (bFGF) for 2 weeks stimulated osteoblast proliferation and new bone formation in various skeletal bones in young and aged rats at dosage levels of 0.1 mg/kg/day and greater. Morphometry of the soft X-ray radiograms of cross sections of the tibia indicated about a 20% increase in the calcified bone area of the diaphysis at 0.1 mg/kg/day. The Ca and hydroxyproline contents showed statistically significant increases at this dosage. The new bone formation was found only on the endosteal side, and no periosteal bone formation was found. Similar systemic osteogenic potential was seen after intravenous administration of other growth factors of the FGF family, human acidic FGF and human heparin-binding secretory transforming protein-1. The above results suggest a potential therapeutic role for these growth factors in bone-loss diseases such as osteoporosis.

Aging↗
PubMed1989

The location of filamentous hemagglutinin and pertussis toxin antigens of Bordetella pertussis by immunoelectron microscopy.

Immunoelectron microscopy using colloidal gold-tagged antibodies was used to detect filamentous hemagglutinin (FHA) and pertussis toxin (PT) antigens on the surface and in the cytoplasm of Bordetella pertussis cells. Both gold-tagged antibodies to FHA and PT labeled the aggregates of filamentous material on the surface of sediment-settled phase I cells under static conditions. FHA and PT antigens were detected also on ultrathin sections made after embedding the phase I cells in Lowicryl K4M resin. On the ultrathin sections, intense label of gold-tagged antibodies to FHA and PT was present on the cell surface and also in the cytoplasm, but not in the nucleoid. The aggregates of filamentous material adhering on the surface of phase I cells were most abundant on culture day 3, the end of the logarithmic growth stage, but most of the aggregates were found detached from the cell surface on culture day 5 or 7, the stationary stage. The aggregates were not found on the surface of phase III cells. The present study suggested that FHA and PT antigens were localized on the same cell structure and that both antigens were synthesized in the cytoplasm and secreted across the cell membrane mainly in the logarithmic growth stage of the phase I cells.

Bordetella pertussis↗
PubMed1984

Ultrastructural localization of acid phosphatase activity in plasma cells containing Russell's bodies in periodontitis.

Acid phosphatase activity was examined ultracytochemically in gingival specimens to elucidate the response of plasma cells to Russell's bodies. The acid phosphatase activity was discernible in lysosomes of various morphology, some of which contained Russell's bodies. The acid phosphatase activity was stronger in the peripheries of such lysosomes, but weak activity was also found inside Russell's bodies. These findings indicated that at least some of Russell's bodies formed within the plasma cells were degraded in autophagolysosomes.

Acid Phosphatase↗
PubMed1984

Ultracytochemical studies of capillary endothelial cells in the rat central nervous system.

The ultracytochemical localization of eight hydrolytic enzymes (TMPase, 5'-NPase, TPPase, TTPase, Mg++-ATPase, Ca++-ATPase, ALPase and K+-NPPase) and one oxidative enzyme (MAO) was determined in rat brain capillary endothelial cells. In the somal plasma membrane, the enzymatic activity was mainly located in the antiluminal plasma membrane. This finding was appropriate for enzymes possessing the optimal pH at alkaline ranges, except for alkaline phosphatase. Most enzymes investigated showed a positive reaction on the pinocytotic vesicles of capillary endothelial cells. Differences in the intensity of the enzyme activities of the luminal and antiluminal plasma membranes may reflect the polarity in the capillary endothelial cells and relate to blood-brain barrier mechanisms.

Adenosine Triphosphatases↗
PubMed1983

Ultracytochemical localization of ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase activity in the lacrimal gland of the rat.

The electron-microscopic localization of ouabain-sensitive, K-dependent p-nitrophenylphosphatase (K-NPPase) activity of the Na - K-ATPase complex was studied in the exorbital lacrimal gland of the untreated rat with the use of a newly developed one-step lead-citrate method (Mayahara and Ogawa 1980; Mayahara et al. 1980). In the rat lacrimal gland fixed for 15 min in a mixture of 2% paraformaldehyde and 0.25% glutaraldehyde, an electron-dense reaction product was observed on the plasma membrane of the basal infoldings and the lateral interdigitations of the ductal cells. The most intense reaction product - and thus the major site of the Na - K-ATPase activity - was evident on the basolateral membranes of the cells of the large interlobular ducts; a weak reaction was seen on the basolateral, extensively folded plasma membranes of the small intercalated ducts; no reaction product was observed on the plasma membranes of the acinar cells. Addition of 1) 10 mM ouabain, 2) p-chloromercuri-phenyl-sulfonic acid (PCMB-S), 3) elimination of K-ions from the incubation medium, or 4) preheating abolished completely the K-NPPase reaction. The activity was also substrate-dependent. Mg-ATPase-activity was observed not only in the basolateral membranes of all ductal cells but also in the basal part of the acinar cells and on the walls of blood vessels. This reaction was neither inhibited by ouabain nor activated by K-ions. The precipitate of the Mg-ATPase-activity was localized at the extracellular side of the plasma membrane, whereas the K-NPPase-reaction product was restricted to the cytoplasmic side of the plasmalemma. In contrast, non-specific alkaline-phosphatase (ALPase) activity was missing in cells of the large interlobular ducts, but obvious on the apical plasmalemma of cells lining the small intercalated ducts. With respect to its localization and reactivity pattern the activity of the K-NPPase (member of the Na - K-ATase complex) differs markedly from the Mg-ATPase- and ALPase-activity.

4-Nitrophenylphosphatase↗
PubMed1982

Ultrastructural localization of phosphatases in the testes of the domestic fowl: acid phosphatase and thiamine pyrophosphatase.

ACPase and TPPase activity has been examined in the germinal epithelium of the testes in the domestic fowl. ACPase activity in spermatogonia and spermatocytes was confined to the Golgi complex. In spermatids ACPase activity was seen in the endoplasmic reticulum and nuclear envelope in the phase I and especially in the phase II (the elongating phase). This activity gradually decreased during the next phase III (the elongating phase). This activity gradually decreased during the next phase III, and had disappeared in the final phase IV. The membrane body showed ACPase reaction in the small peripheral vacuoles and cisternal structures surrounding large central vacuoles. ACPase was also present in vesicles surrounding the developing tail. Late spermatids showed an abundance of autophagic vacuoles which had a complex array of ACPase positive delimiting membranes. In Sertoli cells ACPase activity was predominant in the lysosomes. TPPase activity was seen in the cisternae of the Golgi complex in spermatogonia and spermatocytes. In spermatids activity was present in the endoplasmic reticulum during the phase II, but it is lost in later stages. The smaller vacuoles and cisternal structures in the membrane body also showed reaction products. According to the present results it is thought likely that the smaller vacuoles and cisternal structures of the membrane body are of endoplasmic reticulum origin. The autophagic vacuoles in spermatids and the lysosomes of Sertoli cells are considered responsible for the degradation of residual bodies cast off by spermatids.

Acid Phosphatase↗
PubMed1980

A new one-step method for the cytochemical localization of ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase activity.

A new one-step method for the light and electron microscopic localization of the ouabain-sensitive, K-dependent p-nitrophenylphosphatase (K-NPPase) activity of the Na-K-ATPase complex is introduced. The incubation medium contains p-nitrophenylphosphate (NPP) as substrate, lead citrate as the capture reagent, and dimethylsulfoxide (DMSO) as an activator. It is usable at the optimal pH of the K-NPPase, which is about pH 9.0 in the presence of 25% of DMSO. The effects of fixation, lead concentration, and DMSO on the enzyme activity were studied using rat kidney as a test tissue. The fixation of tissues in a mixture of 2% paraformaldehyde and 0.5% glutaraldehyde for 60 min at 0 degrees--4 degrees C preserved 45% of the enzyme activity. In the absence of DMSO, lead citrate (4.0 mM) caused 82% inhibition of the enzyme activity in fixed tissue. However, the addition of DMSO (25%) caused about 3-fold activation of the remaining activity. Cytochemical demonstration of the ouabain-sensitive K-NPPase activity was successfully made by this method at both light and electron microscopic levels.

4-Nitrophenylphosphatase↗