Search PubMed⌕ Search

Biomedical subjects

J Tanaka

Publications and source records attributed to J Tanaka.

At least 307 records · Page 17Linked to original sources
PubMed1997

Imaging of oxygen saturation and distribution of erythrocytes in microvessels.

OBJECTIVE: To construct images of oxygen saturation and the distribution of erythrocytes in a network of microvessels. METHODS: The image of a small group of microvessels under an inverted microscope was incorporated into an image processor through a video camera and was digitized. Based on the information obtained through six visible interference filters of different wavelengths, oxygen saturation and the amount of erythrocytes in microvessels were calculated with a computer. The system was applied to a microvascular bed of isolated rabbit mesentery perfused with a suspension of human erythrocytes. RESULTS: In a steady flow, with lowering of tissue oxygen tension by superfusion with nitrogen-bubbled isotonic saline containing 20 mmol/L sodium dithionite, the decrease of oxygen saturation of erythrocytes from arterioles to venules was imaged. Simultaneously, the distribution of erythrocytes in the microvessels was imaged and the marginal cell-free layer was profiled under high magnification. No significant alteration of the erythrocyte distribution on the deoxygenation of erythrocytes was observed. The exposure of erythrocytes to acidic pH and the decrease of the flow velocity of erythrocytes increased the release of oxygen from the erythrocytes in microvessels. CONCLUSIONS: The present method will be useful for the comprehensive analysis of oxygen transfer in the microvascular network, on the basis of both changes of the oxygen saturation and the flow behavior of erythrocytes.

Animals↗
PubMed1997

[Neuropathology of the basal ganglia in Parkinson's disease with a special reference to its responsible lesion].

It took approximately one century to discover the neuropathologic lesion responsible for Parkinson's disease, of which clinical manifestations were originally described in 1817. Namely, the lesion is located in the substantia nigra pars compacta and is histologically characterized by loss of pigmented nerve cells, formation of Lewy bodies and proliferation of astrocytes. The neuronal loss is observed predominantly in the lateral portion of the pars compacta, more conspicuously in its ventral region where immunoreactivity to tyrosine hydroxylase is also decreased. The formation of Lewy bodies, which are found to be peculiar in Parkinson's disease, may hold a clue to the elucidation of the mechanism of neuronal degeneration. An animal model induced by MPTP stimulates a search for environmental factors capable of initiating the disease.

Animals↗
PubMed1997

Mist particle diameters are related to the toxicity of waterproofing sprays: comparison between toxic and non-toxic products.

Although respiratory failures following exposure to waterproofing sprays have been reported worldwide, their mechanism remains unknown. In this study, we sorted each of 12 commercial waterproofing sprays into either the Toxic Group (No 1-4) or the Non-Toxic Group (No 5-12) and compared the pathological changes produced in the lungs of mice after their inhalation. Then we determined the diameters of each product's mist particles and their adhesion rates to cloth. The 4 products in the Toxic Group, reported as toxic to human beings, caused severe damage to mice lungs, whereas the 8 products in the Non-Toxic Group, not reported as toxic, caused little if any damage. The percentage of particle < or = 10 microns were significantly higher in the Toxic Group than in the Non-Toxic Group. The adhesion rate to cloth correlated to the mean particle diameter and was significantly lower in the Toxic Group than in the Non-Toxic Group. The toxic sprays generated mists of smaller particle diameter than the non-toxic sprays, suggesting that the mist particle diameters of waterproofing sprays are related to their toxicity.

Administration, Inhalation↗
PubMed1997

Human mortality in organophosphate poisonings.

We reviewed 130 admissions of organophosphate poisoning and analyzed the causes of death. Fenitrothion, malathion, dichlorvos, trichlorfon and fenitrothion/malathion were the most frequent chemicals involved. Mortality was 25% (32/130); delay in discovery and transport (18 cases), insufficient respiratory management (8 cases), and severe underlying or co-existing diseases (6 cases) were noted in the lethalities. Insufficient respiratory management consisted of delay in endotracheal intubation (5 cases) and failure in weaning (3 cases). About 3/4 of the severely serum cholinesterase-depressed cases needed ventilators. This suggests that better respiratory management would improve the outcome of organophosphate poisonings. Close observation of the clinical symptoms is essential, and detection of changes in serum cholinesterase may be helpful.

Adolescent↗
PubMed1997

[Primary testicular carcinoid tumor with teratoma: a case report].

A 77-year-old man presented with a painless swelling of the right testis. A high inguinal orchiectomy was done under the diagnosis of testicular tumor. Histologic diagnosis was carcinoid with teratoma. Computerized tomography revealed multiple lung and retroperitoneal lymph node metastases 4 months after orchiectomy. Chemotherapy had no effect on metastases. He died of lung metastasis 3 months after the recurrence.

Aged↗
PubMed1997

Nitric oxide-mediated cGMP synthesis in oligodendrocytes in the developing rat brain.

We investigated the nature of cGMP-synthesizing cells in the developing rat forebrain using cGMP-immunocytochemistry in combination with in vitro incubation of brain slices. When brain slices of immature rats, aged between 1 and 4 weeks, were incubated with sodium nitroprusside (SNP), a nitric oxide (NO) donor compound, in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX), small round cells with a few processes in and around the corpus callosum were visualized with the cGMP-antibody. The morphology and the distribution of the cGMP-positive cells were consistent with the criteria for oligodendrocytes. Furthermore, the cGMP-positive cells expressed 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and gelsolin, which are marker proteins for oligodendrocytes. Therefore, we concluded that the cGMP-positive cells were oligodendrocytes. A subpopulation of the oligodendrocyte was found to be cGMP-immunoreactive also when slices were incubated in the absence of SNP. Furthermore, incubation of the slice in the presence of L-NAME, an inhibitor of NO synthase, but in the absence of SNP abolished cGMP immunostaining. In addition, some populations of neurons and astrocytes in restricted brain areas produced cGMP in response to the incubation with SNP as previously reported, whereas both ameboid and ramified microglial cells did not respond to the treatment. Atrial natriuretic peptide, a stimulator of particulate guanylyl cyclase, enhanced cGMP synthesis in astrocytes in some brain regions but not in oligodendrocytes. These findings indicate that oligodendrocytes in the immature rat brain express soluble guanylyl cyclase. No cGMP-positive oligodendrocytes were found in the mature rat brain, suggesting that cGMP may mediate signals related to myelinogenesis in the rat brain.

1-Methyl-3-isobutylxanthine↗
PubMed1997

Trigonal splitting is a major complication of endoscopic trigonoplasty at 1-year followup.

PURPOSE: The long-term results of endoscopic trigonoplasty in patients with vesicoureteral reflux were investigated. MATERIALS AND METHODS: We performed endoscopic trigonoplasty in 28 patients with vesicoureteral reflux, including 6 girls 6 to 8 years old. Reflux was grade I in 14 reno-ureteral units, grade II in 15, grade III in 8, grade IV in 1 and grade V in 1. Median followup was 23 months. RESULTS: At a median of 3 months postoperatively vesicoureteral reflux was not apparent in 37 units (95%) and it was downgraded in 1 (3%). At a median of 12 months postoperatively 27 (79%) and 4 (12%) of the 34 ureters had cessation and downgrading, respectively. Of the 13 select patients who underwent cystoscopy 3 had retreating ureteral orifices and 5 had trigonal splitting 6 to 12 months postoperatively. Vesicoureteral reflux was demonstrated in 3 of the 5 patients (4 ureters) with trigonal splitting and in 1 (1 ureter) with retreating ureteral orifices. At a median of 24 months after surgery voiding cystography showed reflux in only 1 of 15 units. No postoperative upper urinary tract dilatation was noted at followup. CONCLUSIONS: Cessation rates of vesicoureteral reflux 12 months after endoscopic trigonoplasty were low with a high incidence of trigonal splitting. These unsatisfactory results mandate technical refinements to avoid trigonal splitting.

Adolescent↗
PubMed1997

Glucocorticoid- and mineralocorticoid receptors in microglial cells: the two receptors mediate differential effects of corticosteroids.

Effects of steroid hormones on the regulation of function and morphology of microglial cells were investigated using the cultured cells isolated from forebrain of newborn rats. Cortisol, corticosterone, and aldosterone at 100 nM caused a strong shrinkage of microglial cells cultured in a serum-supplemented medium. However, cholesterol, pregnenolone, testosterone, estradiol, and dehydroepiandrosterone did not exhibit any significant effects. The corticosteroids also inhibited the GM-CSF-mediated ramification of microglia in a serum-free medium. An anti-glucocorticoid agent RU38486 abolished the effects of corticosteroids on the microglial morphology, suggesting the presence of functional glucocorticoid receptor (GR) in microglial cells. The presence of GR was confirmed by immunoblotting with an antibody to the receptor. Cytokines GM-CSF and interleukin-3 altered the level of GR expression. Binding experiments with [3H]-corticosterone demonstrated the presence of not only GR but also mineralocorticoid receptor (MR): the dissociation constants (Kd) and the number of binding sites (Bmax) were 0.8 nM and 15 fmol/mg protein for MR and 5.0 nM and 73 fmol/mg protein for GR, respectively. The pure glucocorticoid RU28362 and dexamethasone at 20 nM (but not aldosterone and corticosterone at the same concentration) inhibited proliferation of microglial cells, as revealed by PCNA immunocytochemistry. RU28362 inhibited the activities of inducible nitric oxide synthase and acid phosphatase at concentrations higher than 1 nM. Aldosterone and corticosterone exhibited the similar inhibitory effect at 100 nM, and this inhibition was completely overcome by RU38486. On the other hand, corticosterone and aldosterone at concentrations lower than 1 nM enhanced the activities of both enzymes. The antimineralocorticoid agent spironolactone eliminated the stimulatory effects of corticosterone on the enzyme activities. In accordance with these biochemical results, electron microscopic observations revealed that glucocorticoids enhanced the formation of lysosomal vacuolation in microglial cells and aldosterone increased the number and size of lysosomes. In conclusion, it is suggested that GR and MR mediated the opposite effects of corticosterone on the functions of microglial cells; the hormone acted as an inhibitor through GR and as an stimulator through MR.

Adrenal Cortex Hormones↗
PubMed1997

v-Rel activates the proto-oncogene c-Jun promoter: a correlation with its transforming activity.

v-Rel is a transforming protein of the reticuloendotheliosis virus, and is a transcription factor regulating various cellular genes. We found that v-Rel activates the promoter of the proto-oncogene c-jun in a transient transfection assay system. Moreover, the expression of endogenous c-jun was augmented in cells expressing exogenous v-Rel, but not c-Rel. The transcriptional activities of v-Rel to the tested promoters containing the kB-site are lower than that of c-Rel, but that to the c-jun promoter was much higher than that of c-Rel. The N-terminal DNA binding domain of v-Rel, which is responsible for its high transforming activity of v-Rel was also responsible for the high transcriptional activity to the c-jun promoter. Thus, the activity of v-Rel upon the c-jun promoter correlates well with its transforming ability. Since c-Jun plays pivotal roles on cell proliferation in various types of cells, the activation of c-jun expression by v-Rel may be an essential step for the oncogenic transformation caused by v-Rel.

Binding Sites↗
PubMed1997

[Laparoscopic retrieval of a dislocated ventriculoperitoneal shunt catheter: report of three cases and a review of the literature].

Described are 3 cases of a disconnected ventriculoperitoneal shunting system that was successfully retrieved by using a laparoscopic procedure, with a review of the literature. All patients had symptoms of increased intracranial pressure. Roentgenograms showed disconnection of a ventriculoperitoneal shunt catheter at the connecting device and its migration into the peritoneal cavity. A laparoscope was introduced into the peritoneal cavity using the double puncture procedure and the catheter was extracted in less than 15 minutes. The use of a laparoscope enabled exploration of the entire space of the cavity without any large laparotomy incision. Furthermore, the laparoscopic procedure also easily enabled introduction of a replaceable ventriculoperitoneal shunt catheter into the appropriate portion in the cavity and confirmed the CSF flow into the cavity. Because catheters which have migrated into the cavity might cause an acute abdomen, it is important that they should be removed as soon as possible. It should be kept in mind, during the procedures of extracting catheters, that the inner absorptive surface of the peritoneal cavity must be preserved as much as possible. In this regard, laparoscopic retrieval of disconnected shunt catheters is a promising method.

Adult↗
PubMed1997

Toxicity of waterproofing spray is influenced by the mist particle size.

In a previous study, we showed that waterproofing sprays that are toxic generate mists with smaller particles than do nontoxic products. In this study, we made 4 waterproofing sprays (A, B, C and D) with identical ingredients but with different mist particle sizes and compared the pathological changes produced in the lungs of mice. The mist particle diameters were 32.8 +/- 3.2, 62.0 +/- 3.8, 89.1 +/- 4.1 and 143.2 +/- 5.0 microns for sprays A, B, C and D, respectively. Pathological lung changes were evaluated by a 6-criteria grading system (thickening of the alveolar septum, cellular infiltrations in the alveolar septum, alteration of the bronchial mucous membrane, hyperemia of the alveolar wall, transudative hemorrhage, and alveolar collapse). Sprays A and B caused significantly greater scores as compared to the control group for all the criteria except mucosal changes, whereas the changes from sprays C and D were slight and the differences in scores were not significant. These results suggest that toxicity of waterproofing spray is influenced by the mist particle size generated and may help manufacture safer waterproofing spray products.

Aerosols↗
PubMed1997

[A case of post-radiation constrictive pericarditis developing 12 years after radiation therapy].

A 70-year-old woman underwent radical mastectomy for carcinoma of the left breast in 1982. Postoperative radiation therapy was given in a total dose of 50 Gy for parasternal and left subclavian nodes. Symptoms of heart failure such as exertional dyspnea, facial edema, and hepatomegaly manifested in 1992. Cardiac catheterization revealed marked elevation of mean right atrial pressure and right ventricular end-diastolic pressure. The pressure wave form of the right ventricle showed the so called "dip and plateau" feature. Pericardiectomy without using extracorporeal circulation was performed in 1994. Operative findings and pathological study results were compatible with radiation-induced constrictive pericarditis. She rapidly recovered from heart failure after this operation, and has done very well to date.

Aged↗
PubMed1997

Hydrophobic effect of alkyl substituents on DNA intercalation of a dye.

Naphthalene imides carrying alkyl chains of different length were synthesized to evaluate the hydrophobic effect on DNA interaction with small molecules. These dyes bind to DNA with moderately high affinity of 10(4)-10(5) M-1 and raise the melting temperature of the DNA duplex by 8-18 degrees C at a 0.2 molar ratio of dye to DNA-p (phosphate unit). However, both the DNA binding affinity and DNA duplex stability decrease with an increase in the hydrophobicity (logP) of the dye. These results demonstrate that the interaction of the hydrophobic alkyl chain of the dye with the DNA groove destabilizes the DNA structure, presumably by removing the structure-stabilizing water from the DNA groove.

Alkylation↗
PubMed1996

Effects of bromocriptine and/or L-DOPA on neurons in substantia nigra of MPTP-treated C57BL/6 mice.

The effects of bromocriptine and/or L-DOPA on substantia nigra neurons of MPTP-intoxicated mice were investigated. L-DOPA reduced the number of neurons. Bromocriptine protected the neurons from damage by L-DOPA but had no effect on the neurons damaged by MPTP. The treatment of bromocriptine and L-DOPA protected the neurons compared with single administration of bromocriptine. It seems reasonable to suppose that bromocriptine should be added to L-DOPA in order to protect the neurons in parkinsonism.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1996

An effect of K-ras gene mutation on epidermal growth factor receptor signal transduction in PANC-1 pancreatic carcinoma cells.

The Ras protein is involved in tyrosine kinase signal transduction pathway steps such as EGFR signalling. Most human pancreatic carcinomas harbor a point mutation of K-ras oncogene and overexpress transforming TGF-alpha. We studied how K-ras gene mutation could influence the EGFR signal transduction mechanism and the autonomous proliferation of pancreatic carcinoma cells, using PANC-1 human pancreatic carcinoma line and W1-38 normal human fibroblast cell line as a control. PANC-1 cells responded to neither EGF nor exogenous TGF-alpha, although anti-TGF-alpha MAb suppressed their growth. Expression of TGF-alpha mRNA was detected only in PANC-1 cells, which confirmed EGFR being within an autocrine loop. Ras protein and MAP kinase were constitutively activated in PANC-1 cells so that the cells did not respond to treatment with staurosporine or herbimycin A, and exhibited slight response to EGF stimulation. PANC-1 cells harbored K-ras gene mutation in codon 12. In contrast, EGF stimulation induced an elevation of GTP-bound ratio to Ras protein and an activation of MAP kinase with accelerated growth in W1-38 cells. From these findings, we concluded that K-ras gene mutation possibly plays an important role in the autonomous proliferation of PANC-1 pancreatic carcinoma cells, and that an autocrine loop represented by TGF-alpha and EGFR may further accelerate the growth of PANC-1 cells.

Antibodies, Monoclonal↗
PubMed1996

Interactions and properties of smooth muscle myosin phosphatase.

Interactions of the type 1 phosphatase catalytic subunit (PP1c) and the myosin phosphatase holoenzyme (MBP) were compared using affinity columns. In the absence of ATP, MBP bound to dephosphorylated myosin, heavy meromyosin (HMM), and subfragment 1. In contrast, PP1c was not bound. In the presence of ATP, the binding of MBP occurred only with phosphorylated protein. The interaction of MBP with phosphorylated proteins also was demonstrated using thiophosphorylated proteins as competitive inhibitors. Kinetics parameters were determined. With phosphorylated light chains (P-LC20), the major difference between PP1c and MBP was a lower K(m) for the latter. With myosin, MBP showed a marked increase in kcat, compared to PP1c. ATP did not affect these parameters. To investigate the role of the large phosphatase subunit, two recombinant proteins representing the N-terminal two-thirds of the molecule were expressed. These activated PP1c, and activation was maximum at approximately an equimolar ratio. The equimolar mixture of recombinant fragment and PP1c exhibited K(m) values similar to MBP and increased kcat values, compared to PP1c alone. An affinity column was prepared using the recombinant fragment. Phosphorylated HMM and P-LC20 were bound in the presence and absence of ATP. The interaction of P-LC20 was not ATP-dependent. Dephosphorylated HMM did not bind in the presence of ATP. The N-terminal fragment of the large subunit also contained a binding site for PP1c. These results indicate that the N-terminal portion of the large subunit of MBP contained binding sites for P-LC20 and PP1c.

Adenosine Triphosphate↗