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Biomedical subjects

S Maeda

Publications and source records attributed to S Maeda.

At least 649 records · Page 36Linked to original sources
PubMed1991

[A case of retroperitoneal venous aneurysm].

Venous aneurysm is a rare entity and the disease occurring in the retroperitoneal space has been reported in only 4 cases. Therefore, the fifth case of retroperitoneal venous aneurysm on the literature was described. A 59-year-old male was referred to our clinic because of painless large mass in the left abdomen. Computed tomography, ultrasonography, and magnetic resonance imaging revealed a cystic mass at the perinephric space. The resected cyst contained yellow-grayish fluid. The cyst wall was microscopically formed of 4 layers; blood and cholesterin, hyaline, muscle and collagen from the inner to outer side. He is well without any trouble after the operation.

Aneurysm↗
PubMed1990

Effect of sodium chloride concentration on fluid-phase assembly and stability of the C3 convertase of the classical pathway of the complement system.

The assembly of the classical-pathway C3 convertase from C4 and I2-treated C2 by the action of C1s is an Mg2(+)-dependent reaction. The Mg2+ concentration necessary for the assembly of C3 convertase in the fluid phase was found to be dependent on NaCl concentration. In the absence of NaCl more than 5 mM-MgCl2 was found to be required, whereas 0.5 mM-MgCl2 was adequate for the assembly of C3 convertase in the presence of 150 mM-NaCl. The C3 convertase assembled in a low-ionic-strength buffer was extremely labile compared with that assembled in buffer of physiological ionic strength, and the stability of C3 convertase was improved with the increase in NaCl concentration. It was found that the stabilizing effect of NaCl on C3 convertase was due to inhibition of the dissociating activity of C2b, which was formed during the assembly of C3 convertase. In addition to the dissociation-accelerating effect, C2b inhibited the assembly of C3 convertase in low-ionic-strength buffer, and this effect also was diminished with increase in NaCl concentration. An increase in NaCl concentration to more than 200 mM resulted in a decrease in the assembly of C3 convertase. This effect was not due to the lability of the assembled C3 convertase but due rather to the inhibition of C2 cleavage by C1s. Purified C3 convertase itself is stable in dilute medium or high-ionic-strength medium such as 500 mM-NaCl, suggesting that the interactions between C4b and C2a are hydrophobic. In these respects C2b seemed to be functionally similar to C4bp, but C2b failed to act as a cofactor for the Factor I-catalysed C4b cleavage.

Complement C2↗
PubMed1990

Internalization of the Hm1 muscarinic cholinergic receptor involves the third cytoplasmic loop.

The m1 muscarinic receptor was previously shown to stimulate phosphatidyl inositol (PI) turnover and to internalize rapidly upon agonist activation. Three receptor mutants with large deletions of the third cytoplasmic loop (i3) of human Hm1, leaving only 11 and 8 amino acids at the amino and carboxy terminal junctions of i3, respectively, retained full ability to stimulate PI turnover, when expressed in U293 cells, but receptor internalization was greatly reduced in two mutants with deletions reaching close to the NH2 terminal of i3. We propose that a receptor domain located toward the amino terminal junction of i3 plays a role in Hm1 internalization.

Carbachol↗
PubMed1990

Amplification and overexpression of the epidermal growth factor receptor gene in human renal-cell carcinoma.

We examined 22 cases of renal-cell carcinoma (RCC) for structural alterations of the epidermal growth factor receptor (EGFR) gene and found gene amplification in one case of high-stage-high-grade RCC. Dot blot analysis of the total RNA from tumorous and normal kidney tissues revealed overexpression of the EGFR gene in 12 of 20 (60%) cases of RCC. The highest expression was observed in the gene-amplified case. No correlation was observed between the level of EGFR mRNA and tumor stage or grade. Northern blot analysis revealed normal 10- and 5.6-kb EGFR mRNA bands in RCC. Our data indicate that gene amplification of the EGFR gene is one of the molecular mechanisms of its overexpression in a subset of RCCs.

Blotting, Northern↗
PubMed1990

Antithrombin III Kumamoto: identification of a point mutation and genotype analysis of the family.

We previously reported a variant antithrombin III (AT III Kumamoto) associated with a 31-year-old female who suffered from recurrent thrombotic episodes. To define the molecular basis for the variant AT III, we used a combination of genomic amplification followed by cloning, sequencing, and hybridization with allele-specific oligonucleotide probes. We obtained evidence for a cytosine to thymine transition in exon 2 (codon 47) of the AT III gene in the proband. This mutation converts arginine 47 to cysteine. Oligonucleotide hybridization procedures were used for confirmation of the mutation and for genotype analysis of the family members.

Adult↗
PubMed1990

Phyllodes tumor of the breast: a clinicopathologic study of 34 cases.

Thirty-four cases of phyllodes tumor of the breast were studied to evaluate the clinical and pathological features, which correlate with local recurrence. Histologically, local recurrence correlated with the finding of more than ten mitotic figures per ten high-power fields, marked cellularity, prominent nuclear pleomorphism, and stromal overgrowth. Older patients and patients with larger tumors had a higher probability of local recurrence. Stromal overgrowth correlated with the other histological parameters, with rapid tumor growth, a tumor diameter of over 10 cm, and with local recurrence. It was thus considered to be a histological indicator of the malignant potential of phyllodes tumor of the breast.

Adolescent↗
PubMed1990

Monoclonal antibodies to human germ cell tumors from "routine" paraffin-embedded pathological specimens.

We have established a method for monoclonal antibody (MoAb) preparation from routine paraffin-embedded tissue of human seminoma as an immunogen. Three 40-microns thick sections were deparaffinized and rehydrated. An eight-week-old BALB/c mouse was immunized intraperitoneally with this extract, which showed no detectable protein bands on sodium laurylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Five monoclonal antibodies (MoAbs) with different characteristics were obtained; one reacted with the nucleus, two with the cytoplasm, and two with the cytoplasmic membrane. One of the MoAbs 5G9 reacted with spermatogonia in normal human tissues and with seminoma, embryonal carcinoma and choriocarcinoma in the testicular tumors.

Animals↗
PubMed1990

Alveolar soft part sarcoma: a case report with immunohistochemical study.

We report herein, a rare case of a 28 year old Japanese man with alveolar soft part sarcoma. The patient noticed a rapidly growing mass in the inner aspect of his left thigh and a smooth-surfaced, hard nodule revealing bruit on auscultation was found on physical examination. An angiogram showed dense neovascularity from the left profunda femoris artery. Histopathologically, the tumor was composed of nests of tumor cells with hyperchromatic nuclei and vesicular cytoplasm arranged in an alveolar fashion and a histopathologic diagnosis of alveolar soft part sarcoma was made. Immunohistochemically, the tumor cells had desmin and vimentin immunoreactants in the cytoplasm, suggesting muscle origin.

Adult↗
PubMed1990

Cavernous hemangioma of the stomach: a case report and review of the literature.

A cavernous hemangioma of the stomach in a 41-year-old Japanese man was reported. The patient had numerous hemorrhagic telangiectasias in the skin and was also diagnosed as having a submucosal tumor of the stomach by an incidental upper gastrointestinal X-ray study. Wedge resection of the stomach was performed. The tumor was located in the submucosal, proper muscular and subserosal layers. The resected specimen showed proliferation of vascular spaces lined with a layer of endothelial cells and filled with red blood cells together with a partially calcified thrombus. The histopathologic diagnosis was cavernous hemangioma of the stomach with calcified thrombus. The patient has been doing well for twenty years. We report the case and briefly review the literature.

Adult↗
PubMed1990

Immunocytochemical evaluation of abl-gene products in leukemic cell lines.

We raised monoclonal antibody (MAb) against a synthetic oligopeptide corresponding to a portion of the predicted v-abl protein sequence (379-390). This MAb reacted with all of the abl-gene products (p145c-abl, p150c-abl and p210bcr-abl fused protein) and was not specific for any one of them. Immunocytochemically, we investigated the expression and localization of the abl-gene products in various leukemic cell lines. Positive immunoreactions were observed in Ph1 positive leukemic cell lines (K562 and KU-812) and erythro-leukemic cell lines (HEL and K3D) and were located on the cell membrane. Electron microscopically, a different distribution pattern was observed among the cell lines: linear and almost even in Ph1 positive leukemic cell lines, whereas spotted or budding-like in erythroleukemic cell lines. Ph1 translocation produces p210bcr-abl fused protein with not only altered autophosphorylation activities but also altered subcellular distribution patterns.

Animals↗
PubMed1990

Reduction of serum lipoprotein(a) levels in hyperlipidaemic patients with alpha-tocopheryl nicotinate.

The effect of low dose (600 mg/day) alpha-tocopheryl nicotinate on serum lipoprotein(a) (Lp(a] concentration was studied in 28 hyperlipidaemic patients. Serum lipids, lipoproteins and apolipoproteins, except for Lp(a), tended to increase after treatment. In particular, the changes in HDL-cholesterol and apo C-II levels were statistically significant. On the other hand, serum Lp(a) levels in all patients decreased significantly after 2 months of treatment. Furthermore, no difference between before and after treatment was observed in the group with initial Lp(a) levels less than 18 mg/dl, whereas Lp(a) concentrations decreased significantly after treatment in the group with levels greater than or equal to 18 mg/dl. The effects of probucol and alpha-tocopheryl nicotinate on serum Lp(a), total cholesterol and HDL-cholesterol were entirely different. Possible mechanisms of alpha-tocopheryl nicotinate on serum Lp(a) and lipoprotein metabolism are discussed.

Adult↗
PubMed1990

Glucose inhibits myo-inositol uptake and reduces myo-inositol content in cultured rat glomerular mesangial cells.

Although activation of polyol pathway has been proposed as one of the etiologic factors of diabetic complications, precise mechanism of the effect of polyol accumulation is still unclear. In order to test the hypothesis that there is an association of polyol pathway with myo-inositol metabolism, we measured myo-inositol content in cultured rat glomerular mesangial cells. By exposing the cells to high concentrations of glucose, intracellular myo-inositol content was reduced from 12.39 +/- 0.64 nmol/mg protein at 0 mmol/L glucose to 6.54 +/- 0.38 nmol/mg protein at 27.5 mmol/L glucose and 4.88 +/- 0.43 nmol/mg protein at 55 mmol/L glucose. This decrease of myo-inositol content was partially prevented by co-incubation with aldose reductase inhibitor, sorbinil. To examine further the mechanism of myo-inositol depletion, myo-inositol uptake by mesangial cells was studied. Major myo-inositol uptake process was sodium-dependent, saturable, and ouabain sensitive with Vmax of 171 pmol/mg protein/20 min and Km of 33 mumol/L. Sodium-dependent myo-inositol uptake was significantly inhibited by glucose in a dose-dependent manner only when glucose was present during uptake experiment, and kinetic analysis revealed the inhibition was competitive. Aldose reductase inhibition failed to prevent inhibitory effect of glucose on myo-inositol uptake. These data suggest that myo-inositol content of glomerular mesangial cells, which is reduced by high concentrations of glucose, is maintained by two processes: a glucose-sensitive but sorbitol-insensitive process, sodium-dependent myo-inositol uptake; and a sorbitol (aldose reductase) sensitive process, myo-Inositol depletion under high glucose condition may induce dysfunction of mesangial cells seen in diabetes.

Aldehyde Reductase↗
PubMed1990

Electron microscopic study of acute retrograde pyelonephritis in mice.

A strain of Escherichia coli O6:H-, which was isolated from a patient with acute pyelonephritis, was used to produce ascending pyelonephritis in mice. The histologic features at the early stage of acute pyelonephritis and the pathways of bacterial invasion and distribution in the infected kidneys were studied by using transmission electron microscope. The histologic changes were characterized by degeneration and destruction of renal pelvic and tubular epithelial cells, and a massive infiltration of polymorphonuclear leukocytes. Bacteria invaded the pelvic surface and spread over the renal medulla and cortex by contiguity twelve hours after infection. It was also shown that bacteria ascended the tubules, multiplied in the tubular lumina, destroyed the tubular epithelial cells, and spread over the renal cortex by twelve hours. In addition, bacteria and leukocytes phagocytizing bacteria were present in the capillaries in the renal interstitium twelve hours after infection.

Acute Disease↗
PubMed1990

Acute cytogenetic effects of tyramine and MTCAs on mouse bone marrow cells in vivo by the micronucleus test.

We studied the acute cytogenetic effects of tyramine and MTCAs--precursors of the mutagen present in soy sauce--on mouse bone marrow cells in vivo by the micronucleus test. The incidence of MNPCE in bone marrow cells gradually increased and reached a maximum level 24 h after intraperitoneal injection of tyramine or MTCAs and decreased within 36 h. A dose-dependent increase in MNPCE was clearly observed for both compounds. Compared to the values for the untreated control, significant positive results were obtained with 0.5 mmole tyramine/kg (68.5 mg/kg) and with 0.1 mmole MTCAs/kg (23 mg/kg) 24 h after intraperitoneal administrations. Micronuclei were significantly induced but no severe reduction in the ratio of PCEs/NCEs was observed.

Animals↗
PubMed1990

Acute cytogenetic effects of tyramine, MTCAs, NaCl and soy sauce on rat bone marrow cells in vivo.

The acute cytogenetic effects of tyramine and MTCAs, precursors of the mutagen present in soy sauce, were studied with the in vivo chromosome aberration test in rat bone marrow cells. The chemicals were administered intraperitoneally. Statistically significant positive results were obtained with tyramine at a dose of 5 mmole/kg (686 mg/kg) body weight and with MTCAs at doses over 0.50 mmole/kg (115 mg/kg) body weight, respectively. Chromosome aberrations (CA) induced by L-proline co-administered with either tyramine or MTCAs were significantly lower than those induced by each chemical alone. These data suggest that L-proline, after endogenous nitrosation, became nitrosoproline and suppressed CA, and that, as a result of in vivo nitrosation of tyramine and MTCAs, they became mutagenic nitroso compounds showing positive results. Statistically significant positive results were obtained by administration of 40 mmole NaCl/kg body weight (2338 mg/kg). The cocarcinogenic role of NaCl with tyramine was suggested because soy sauce contains about 18% NaCl.

Animals↗