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Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 487 records · Page 27Linked to original sources
PubMed1994

Elevation of serum group II phospholipase A2 levels in patients with advanced cancer.

To investigate the role of group II phospholipase A2 (M-PLA2) in cancer, we examined M-PLA2 serum levels in 170 pre-operative patients with various cancers and found elevated levels in 49% of them. M-PLA2 serum levels were significantly higher in patients with tumor stages T2-4, N1, M1 and stages II to IV than in T1, N0, M0 and stage I tumors, respectively. In all nine post-operative patients tested, M-PLA2 decreased 14 days after tumor resection and reduced to normal levels in 4 patients. Six of 16 carcinoma cell lines (37.5%) spontaneously secreted M-PLA2 into the culture supernatant despite the absence of IL-6 and IL-1 in 5 of the 6 lines. These results demonstrate that M-PLA2 produced by cancer cells may contribute, at least in part, to the elevation of serum M-PLA2 levels observed in cancer patients.

Bile Duct Neoplasms↗
PubMed1994

N-nitroso compounds in two nitrosated food products in southwest Korea.

Gastric cancer is the commonest malignant neoplasm in Southwest Korea. The possibility of carcinogenic dietary factors led to the investigation of exposure to N-nitroso compound precursors among residents of the City of Chonju and of two outlying rural townships in North Cholla Province. Two traditional and widely consumed home-prepared food products, salted pickled cabbage (kimchi) and salted seafood sauce (chut-kal) were analysed (a) for nitrite, nitrate, total secondary amines and pH in these food products prior to nitrite incubation and (b) for volatile nitrosamines and total N-nitroso compounds before and after incubation with nitrite in simulated human stomach conditions. Nitrate levels were significantly higher in kimchi (median 1550 mg/kg) than in chut-kal (median 140 mg/kg) (P < 0.001). Secondary amine levels in non-nitrosated samples of kimchi (median 5.5 mg/kg) were significantly lower than secondary amine levels in non-nitrosated chut-kal (median 56 mg/kg) (P = < 0.001). Analyses of nitrite-incubated kimchi revealed high levels of total N-nitroso compounds (median 1173 micrograms/kg); the increase with nitrosation was significant (P = 0.001). The concentration of N-nitroso compounds in nitrite-incubated kimchi was significantly greater than that found in nitrite-incubated chut-kal (P = 0.015). The combination of high levels of nitrate in the kimchi, the demonstration of high levels of total N-nitroso compounds in this food after nitrosation, and the volume of kimchi consumed in the traditional diet suggest that salted pickled cabbage may play a role in gastric carcinogenesis in Southwest Korea.

Amines↗
PubMed1994

Elevation of circulating interleukin 6 after surgery: factors influencing the serum level.

To investigate the effect of surgical trauma and other factors on the postoperative elevation of serum interleukin 6 (IL-6), we examined changes in IL-6 concentration after major thoracoabdominal surgery. Serum IL-6 levels reached the maximum concentration on the first postoperative day in all 38 patients, with peak ranging from 1400.8 +/- 383.4 pg/ml (mean +/- SEM) to 29.8 +/- 3.8 among six groups who underwent surgery at different sites. The IL-6 peak was significantly correlated with surgical trauma as defined by the operation length and the volume of blood loss during surgery (r = 0.554, P < 0.01 and r = 0.427, P < 0.01, respectively). The peak concentration of serum IL-6 in patients undergoing esophagectomy was significantly higher than in those undergoing pancreaticoduodenectomy (P < 0.05), despite a similar degree of surgical trauma defined by the operation length and volume of blood loss during surgery. Peak IL-6 concentration observed in a patient who underwent esophagectomy was about 100-fold greater in fluid drained from the thorax than in the peripheral blood. IL-6 mRNA was demonstrated in leukocytes from thoracic and abdominal exudate at 6, 24 and 48 h after surgery. In contrast, IL-6 mRNA could not be detected in leukocytes from the peripheral blood. Similar findings were also observed for interleukin 8 (IL-8). However, interleukin 1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF-alpha) were detected only once after surgery in the drainage fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Contrast-enhanced MR imaging of dural sinus thrombosis: demonstration of the thrombosis and collateral venous channels.

In order to study the role of Gd-DTPA-enhanced MR imaging in dural sinus thrombosis, precontrast and postcontrast imaging using Gd-DTPA in three patients with clinically unsuspected dural sinus thrombosis was reviewed. Comparisons were made with cranial CT scanning and cerebral angiography. Compared to CT, the postcontrast T1-weighted images more clearly revealed thrombus in the dural sinuses as a nonenhanced central area of intermediate intensity (but not flow void) surrounded by an enhanced rim. MR imaging also demonstrated secondary changes, including the presence of collateral venous channels and venous infarction.

Adult↗
PubMed1994

Method for selecting anthocyanin-producing cells by a cell sorter.

We found a novel method to select anthocyanin-producing cells by a new means of cell staining. After staining with 0.2 ppm fluorescein isothiocyanate (FITC), the protoplasts from Aralia cordata cultured cells, which were composed of high anthocyanin-producing cells and non-producing cells, were observed to be distinguishable under a fluorescence microscope. The green fluorescence of FITC from the non-producing cells was clearly ascertained by the naked eye. On the other hand, the fluorescence of the anthocyanin-producing cells was completely missing. This phenomenon resulted from compensation of the green fluorescence (lambda max 525 nm) of FITC and the green light absorption (lambda max 530 nm) of anthocyanin. Although investigations of the flow cytometric method were developed on the basis of this phenomenon, the histograms of these protoplasts expressed the distinction between the anthocyanin-producing cells and the non-producing cells. In order to prove the technique, a highly productive cell line was selected from the heterogeneous populations of anthocyanin-producing or non-producing protoplasts from A. cordata cultured cells. The number of the sorted protoplasts containing anthocyanin was counted by the naked eye, the anthocyanin-producing protoplasts were approximately 90% in the whole protoplasts and the viability was 60-70%. Anthocyanin concentration the sorted protoplasts was 3-fold higher as compared with the protoplasts before sorting. The anthocyanin content of the cell line selected by this method was 7.7 +/- 0.6%/g dw.(ABSTRACT TRUNCATED AT 250 WORDS)

Anthocyanins↗
PubMed1994

Nitric oxide opens ATP-sensitive K+ channels through suppression of phosphofructokinase activity and inhibits glucose-induced insulin release in pancreatic beta cells.

Nitric oxide (NO) is known to be a potent messenger in the intracellular signal transduction system in many tissues. In pancreatic beta cells, NO has been reported to be formed from L-arginine through NO synthase. To elucidate the effect of NO on insulin secretion and to investigate the intracellular mechanism of its effect, we have used sodium nitroprusside (SNP) as a NO donor. SNP inhibited glucose-induced insulin secretion in a dose-dependent manner, and its effect was reversed by hemoglobin, a known NO scavenger. However, glyceraldehyde-induced insulin secretion was not affected by SNP. Since the closure of ATP-sensitive K+ channels (KATP channel) has been established as a key step in glucose-induced insulin secretion, we have directly assessed the effect of SNP on KATP channel activity using the patch clamp technique. The KATP channel activity reduced by glucose was found to be reversibly activated by the addition of SNP, and this activation was able to be similarly reproduced by applying S-Nitroso-N-acetyl-DL-penicillamine (SNAP), another NO generator. Furthermore, these activating effects were completely eliminated by hemoglobin, in accordance with the reversibility in inhibition of glucose-induced insulin release. However, SNP could not affect the KATP channel suppression by ATP applied to the inside of the plasma membrane. The activation of the KATP channel by NO, therefore, seems to be due to the decreased ATP production attributable to impairment of glucose metabolism in beta cells. Since SNP exhibited no effect on glyceraldehyde-induced KATP channel inhibition, NO may disturb a glycolytic step before glyceraldehyde-3-phosphate. The KATP channel activation by 2-deoxyglucose through presumable ATP consumption due to its phosphorylation by glucokinase was, however, not affected even in the presence of SNP. But in the permeabilized beta cells made by exposure to a low concentration (0.02 U/ml) of streptolysin O (open cell-attached configuration), SNP reopens KATP channels which have been eliminated by fructose-6-phosphate, while this effect was not observed in the KATP channels inhibited by fructose-1,6-bisphosphate. On the other hand, in rat ventricular myocyte KATP channels were not activated by SNP even under a low concentration of glucose. From these observations, the inhibition of phosphofructokinase activity is probably the site responsible for the impairment of glucose metabolism induced by NO in pancreatic beta cells. NO, therefore, seems to be a factor in the deterioration of glucose-induced insulin secretion from pancreatic beta cells through a unique intracellular mechanism.

Adenosine Triphosphate↗
PubMed1994

Structural studies on the tri- and tetrasaccharides isolated from porcine intestinal heparin and characterization of heparinase/heparitinases using them as substrates.

We prepared a series of oligosaccharides from porcine intestinal heparin after extensive digestion with a mixture of Flavobacterium heparinase as well as heparitinases I and II. Previously, we reported the structures of the two glycoserines derived from the carbohydrate-protein linkage region [Sugahara et al., J. Biol. Chem., 267, 1528-1533 (1992)] and three tetrasaccharides derived from the antithrombin III-binding site [Yamada et al., J. Biol. Chem., 268, 4780-4787 (1993)]. In this study, we determined the structures of 10 other tetrasaccharides and a trisaccharide by enzymatic digestion, fast atom bombardment mass spectrometry and 500-MHz 1H NMR spectroscopy. These tetrasaccharides share the common disulphated structure, delta HexA alpha 1-4GlcN(N-sulphate)alpha 1-4IdoA(2-sulphate)alpha 1-4GlcN (where HexA is hexuronic acid and IdoA is L-iduronic acid), and their structural variations are based upon the positions of additional sulphate groups. Eight among the 10 have never been isolated as discrete structures. The structure of the trisaccharide is GlcN(N-sulphate)alpha 1-4IdoA(2-sulphate) alpha 1-4GlcN(N,6-disulphate) and is derived from the non-reducing terminus of heparin chains. This structure may represent the terminus of a biosynthetically formed native heparin chain or a newly formed non-reducing terminus exposed by a tissue endo-beta-glucuronidase which may be involved in the intracellular post-synthetic fragmentation of macromolecular heparin. The 11 structures characterized in the present study and 6 additional tetrasaccharides were used to investigate the substrate specificities of heparinase, as well as heparitinases I and II. The results indicate that modification of the adjacent glucosamine on the reducing side of the disaccharide cleavage site influences the enzymatic action of the lyases, whereas the adjacent uronic acid on the non-reducing side is not recognized by these enzymes.

Animals↗
PubMed1994

Inhibitory effects of daunorubicin on endothelium-dependent vasorelaxing response to acetylcholine of rat aorta.

The effect of daunorubicin on the endothelium-dependent vasorelaxing response to acetylcholine was investigated using rat isolated aorta and compared with the effect of aclarubicin. Treatment of aortic strips with daunorubicin (20 microM) significantly attenuated the relaxing response to acetylcholine in the absence of tetraethylammonium, but not in its presence. Pretreatment with daunorubicin at a higher concentration (50 microM) or with aclarubicin (20 microM) strongly attenuated the relaxing response to acetylcholine; this attenuation was unaffected by the presence of tetraethylammonium. The increase in aortic cGMP in response to acetylcholine was also significantly suppressed by pretreatment with 50 microM daunorubicin or 20 microM aclarubicin, but not by treatment with 20 microM daunorubicin. The inhibitory effect of 20 microM aclarubicin on the acetylcholine-induced responses was stronger than that of 50 microM daunorubicin. Even in strips pretreated with both 50 microM daunorubicin and 20 microM aclarubicin, relaxation induced by 0.1 microM sodium nitroprusside was retained. These results suggest that daunorubicin at 20 microM inhibits the endothelium-dependent vasorelaxing response to acetylcholine via a mechanism other than the nitric oxide-mediated pathway, whilst at 50 microM, it inhibits the nitric oxide-mediated vasorelaxation.

Acetylcholine↗
PubMed1994

Crohn disease: early recognition and progress of aphthous lesions.

PURPOSE: To clarify the radiographic appearance of the initial change an dprogression in Crohn disease. MATERIALS AND METHODS: Between 1984 and 1992, nine patients (seven men and two women, aged 16-34 years; mean, 20 years) with Crohn disease, who had evidence of only aphthous erosions or ulcers at the initial examination, underwent repeated radiography for up to 7 years 11 months (median, 4 years). RESULTS: In all patients, the stomach, duodenum, small intestine, and colorectum were involved, and the esophagus was affected in three patients. Subsequently, four of the nine patients had lesions that progressed from aphthous lesions to overt Crohn disease, including ileitis in two patients, colitis in one, and ileocolitis in one. Time intervals between the first visit and the progression varied from 9 months to 3 years 6 months. In all eight patients who underwent nutritional treatment, regression of the lesions was recognized, but three of the lesions progressed during interruption of the nutritional diet. CONCLUSION: Crohn disease may initially appear as diffuse aphthous lesions in the gastrointestinal mucosa.

Adolescent↗
PubMed1994

Renal cell carcinoma associated with chronic renal failure: evaluation with sonographic angiography.

PURPOSE: To determine the value of sonographic angiography for diagnosis of renal cell carcinoma (RCC) in patients with chronic renal failure (CRF). MATERIALS AND METHODS: The authors compared findings from sonographic angiography, conventional ultrasound (US), computed tomography (CT), and conventional angiography in 15 patients with CRF in whom RCC was suspected. All of these patients subsequently underwent nephrectomy. RESULTS: RCC was demonstrated pathologically in 13 patients, whereas two had benign lesions only. Sonographic angiography depicted tumor enhancement in all patients with RCC except one; no enhancement was shown in the two patients with benign lesions. Conventional angiography depicted tumors stained by contrast material in nine of 13 patients with RCC, and CT depicted tumor enhancement in 10 of 13 patients. US was useful for the detection of nodules but did not allow differentiation of malignant from benign lesions. CONCLUSION: Sonographic angiography has a possible role in the detection of small nodules in patients with CRF.

Adult↗
PubMed1994

Nonparallel secretion of GP-2 from exocrine pancreas implies luminal coupling between acinar and duct cells.

The in vivo and in vitro secretion of glycoprotein-2 (GP-2), a glycosyl phosphatidylinositol (GPI)-anchored protein from the rat exocrine pancreas, was characterized. GP-2 was secreted in a nonparallel manner compared with amylase, a marker of secretory enzymes. Attenuated GP-2 secretion correlated with hormones that stimulated exocytosis in acinar cells. Augmented GP-2 secretion correlated with hormones that stimulated fluid and bicarbonate secretion from ductal elements. Immunofluorescence studies identified an enriched pool of GP-2 tightly bound to the apical membranes of acinar cells in addition to zymogen granules. This non-zymogen granule pool appears to represent the source of GP-2 released from acinar cells in a nonparallel manner. With the use of dispersed pancreatic acini largely devoid of ductal elements, GP-2 release was found to be augmented by alkaline pH. Thus GP-2 secretion appears to be modulated by two discrete cellular processes: 1) delivery of prereleased GP-2 within zymogen granules to the ductal lumen by exocytic mechanisms and 2) enzymatic release of GPI-anchored GP-2 from the luminal membranes, a kinetic process that appears to be regulated by secretin- or carbachol-induced secretion of bicarbonate.

Amylases↗
PubMed1994

Renal pathology in patients with reflux nephropathy. The turning point in irreversible renal disease.

In reflux nephropathy both interstitial and glomerular damage advances with an increase in the scarring grade even in macroscopically normal regions. Based on various histologic findings, sclerosis and the enlargement of glomeruli rapidly accelerate between stages c-a and c-b, as shown by the combined Smellie's scarring grade of the bilateral kidneys. These two steep histologic changes in stage c-b are followed by a remarkable reduction in renal function (DTPA-GFR) and an increase in the amount of urinary protein. These clinicopathological changes thus suggest that hemodynamic changes or overloading in the functional remnant nephrons possibly start in stage c-a. It is also suggested that glomerular enlargement is an index of progressive disease in reflux nephropathy. Among our specimens, most cases of glomerular sclerosis were global while focal segmental glomerulosclerosis was very rare. These findings thus suggest that the global sclerosis observed in our specimens is clearly different from focal segmental glomerulosclerosis.

Adult↗
PubMed1994

Photosensitivity in the circadian hatching rhythm of the carotenoid-depleted silkworm, Bombyx mori.

Silkworms (Bombyx mori) were reared on a carotenoid-deprived artificial diet, and the carotenoid-depleted eggs of the next generation were incubated so that we could observe the effect of the depletion on the circadian rhythm of hatching. The phototactic response curves of newly hatched larvae showed that the visual photosensitivity in ocelli of larvae from the carotenoid-depleted eggs was at least 4 log units lower than that of a carotenoid-rich control group. However, the phase-shift experiment revealed that carotenoid depletion did not reduce the photosensitivity in the hatching rhythm. When the hatching rhythm was generated by exposure to a single light pulse in constant darkness, the first peak in the rhythm of the carotenoid-depleted silkworms occurred significantly earlier than that of the carotenoid-rich group, but the following second peaks of both groups were found at the same time. These results suggest that for the silkworm, carotenoid is not involved in photoreception for the hatching rhythm, but is involved in the timing of hatching.

Animals↗
PubMed1994

A neonatal huge subependymal giant cell astrocytoma: case report.

We report a neonate with a huge subependymal giant cell astrocytoma associated with tuberous sclerosis, with atypical magnetic resonance imaging findings. The neonatal subependymal giant cell astrocytoma is rare, and we discuss the difficulty in its diagnosis and treatment.

Brain Neoplasms↗
PubMed1994

The complete sequences of African horsesickness virus serotype 4 (vaccine strain) RNA segment 2 and 6 which encode outer capsid protein.

The complete sequences of RNA segment 2 and segment 6 of African horsesickness virus serotype 4 (AHSV-4) vaccine strain were determined from cDNA clones inserted into pBR 322. The RNAs of segment 2 and 6 are 3229, 1566 bp long respectively and both contain an open reading frame encoding proteins VP2 and VP5 of 1060, 505 amino acid residues. The estimated molecular weight of VP2 was 124,178 dalton and that of VP5 was 56,793 dalton. Their noncoding end sequences were 5'GTTTAA . . . and . . . ACATAC3' (segment 2), 5'GTTTAT . . . and . . . ACTTAC3' (segment 6). They were different from orbivirus characteristic terminal sequences, which were 5'GTTAAA . . . and . . . ACTTAC3'. The comparison of both sequences of AHSV-4 segment 2 and 6 with those of segment 2 and 5 of bluetongue virus (BTV) serotype 10 revealed 53% nucleotide similarity and 23% amino acid similarity (segment 2), and 58% nucleotide similarity and 46% amino acid similarity (segment 6). In the same way, the comparison of both sequences of the vaccine strain with those of the virulent strain segment 2 and segment 6 of AHSV-4 revealed 91% nucleotide and 96% amino acid similarity (segment 2), and 98% nucleotide and 98% amino acid similarity (segment 6).

African Horse Sickness Virus↗
PubMed1994

Detection of African horsesickness virus by reverse transcriptase polymerase chain reaction (RT-PCR) using primers for segment 5 (NS1 gene).

The reverse transcription followed by the polymerase chain reaction (RT-PCR) technique was applied to the detection of African horsesickness virus (AHSV) using primers specific for attenuated AHSV serotype 4 segment 5 (NS1 gene). Total RNA which contains both messenger RNA and genomic dsRNA was extracted by the acid guanidinium-phenol-chloroform method from the AHSV infected Vero cells and was used as templates to optimize the RT-PCR. A pair of primer (NP2-NP32) amplified the product of the expected size from all serotypes of attenuated AHSV when four pairs of primers were tested. Using this primer pair, no RT-PCR product was detected from the RNA samples extracted from ten other orbiviruses infected cells and their virions. In addition, RT-PCR using a serial dilution of RNA samples suggested that AHSV was efficiently detected from 1 to 2 cells of the cell monolayer infected with 10(6) TCID50 of AHSV. The RT-PCR concerning with total RNAs of AHSV NS1 gene was found to be a specific and sensitive method for the detection of AHSV.

African Horse Sickness↗
PubMed1994

Prognostic impact of the period between surgery and postoperative irradiation in esophageal carcinoma.

One hundred and sixty-two esophageal carcinomas curatively resected and followed by postoperative irradiation were analyzed to investigate whether the delay of postoperative irradiation affected the patients' prognosis. The period of 40 or more days between surgery and postoperative irradiation caused significantly worse survival rates, and this fact was true even if the survival rates were corrected by the other significantly important prognostic factors: age and tumor staging. The incidence of infield recurrence and cancerous death were higher in the patients with the waiting period of 40 or more days. Significant repopulation of residual tumor cells in curatively resected esophageal carcinomas begins 40 days after surgery, therefore, postoperative irradiation should be started within 40 days after a radical resection. The difference of survival rates as related to the waiting period became clear after the follow-up of more than four years. The prognostic difference of subclinical tumors seems to be uncovered several years after treatment.

Adult↗