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Biomedical subjects

K Maeda

Publications and source records attributed to K Maeda.

At least 613 records · Page 34Linked to original sources
PubMed1996

Lamina propria macrophages in the human gastrointestinal mucosa: their distribution, immunohistological phenotype, and function.

In this study we systematically investigated the cellular distribution, immunohistochemical phenotype, and mucosal disposal function of macrophages in the lamina propria of the human gastrointestinal mucosa (lamina propria macrophages; LPMs). In all tissues examined, most of these LPMs accumulated beneath the epithelial layer that covered the apex of the lamina propria of the mucosa. These cells expressed normal levels of common macrophage markers such as CD68, LN5, lysozyme, ferritin, and alpha 1-anti-chymotrypsin. In addition, they expressed high levels of 25F9 (a market for a certain subpopulation of macrophages), MHC Class II molecules, and CD74 (MHC Class II-associated invariant chain). Interestingly, LPMs possessed some epithelial cell-associated antigens such as cytokeratin, carcinoembryonic antigen (CEA), and Ber-Ep4 in their cytoplasm. Ultrastructurally, these antigens were associated with cellular debris ingested by LPMs, which were recognized as apoptotic fragments by in situ end-labeling. Furthermore, double positive-labeled granules were seen in LPMs by double staining for epithelial cell-associated antigens and in situ end-labeling. These observations suggest that one of the major functions of LPMs is the disposal of apoptotic epithelial cells and that LPMs may be involved in the regulation of mucosal epithelial renewal.

Apoptosis↗
PubMed1996

Paraventricular norepinephrine release mediates glucoprivic suppression of pulsatile luteinizing hormone secretion.

Restriction of glucose availability by 2-deoxyglucose (2DG) suppresses pulsatile LH release. The aim of the present study was to determine whether norepinephrine (NE) release in the paraventricular nucleus (PVN) is involved in the glucoprivic suppression of LH secretion in ovariectomized rats. Twelve days after ovariectomy, animals were stereotaxically implanted with a guide cannula for microdialysis in the PVN. Two days later, the PVN was perfused continuously with Ringer's solution or Ringer's solution containing a catecholamine synthesis inhibitor, alpha-methyl-p-tyrosine (100 microM), through a microdialysis probe inserted in the guide cannula 2 h before the beginning of sampling, which lasted 3 h. Blood samples were collected every 6 min through an atrial cannula, and dialysates were collected every 20 min. One hour after the beginning of sampling, 2DG (400 mg/kg BW) was administered iv through the atrial cannula. Paraventricular NE levels significantly increased immediately after 2DG injection (P < 0.05), and both mean LH concentrations and the frequency of LH pulses decreased. By contrast, when alpha-methyl-p-tyrosine was administered into the PVN, 2DG did not produce an increase in paraventricular NE, and no depression of LH secretion occurred. These results suggest that the PVN mediates the glucoprivic suppression of LH pulses via the release of NE.

Animals↗
PubMed1996

Role of endogenous angiotensin II in renal hemodynamic and excretory responses to L-arginine infusion.

The purpose of this study was to investigate whether endogenous angiotensin II has a functional role in renal hemodynamic and excretory changes induced by L-arginine, a substrate for nitric oxide (NO), in anesthetized rats. During the intravenous infusion of L-arginine (50, 100, 200 mumol/kg.min), there was no significant change in systemic or renal hemodynamics, but urine flow and urinary sodium excretion markedly increased in a dose-dependent manner. Simultaneously, L-arginine infusion produced an increase in urinary excretion of NO metabolites, NO2- and NO3-. Treatment with L-158809 ¿5,7-dimethyl-2-ethyl-3-[[2'-(1H-tetrazol-5-yl) [1,1']-biphenyl-4-yl]methyl]-3H-imidazo[4,5-b]pyridine¿ (0.3 mg/kg), a selective angiotensin II type I receptor antagonist, caused a reduction in mean arterial pressure, and a rise in renal blood flow and glomerular filtration rate, with no changes in excretory responses. In the presence of L-158809, L-arginine-induced diuretic and natriuretic actions were observed to the same extent as seen in the absence of L-158809. These data suggest that the infusion of L-arginine causes diuresis and natriuresis, possibly via the formation of nitric oxide in the kidney, and that endogenous angiotensin II is not involved in the L-arginine-induced renal actions.

Anesthesia↗
PubMed1996

QRS alteration-induced torsade de pointes in a patient with an artificial pacemaker and hypokalemia.

The present patient demonstrated torsade de pointes (TdP) after a pacemaker implantation without a decrease in heart rate or pacemaker malfunction. Marked QT prolongation and TdP were closely related to alteration of the depolarization pattern (appearance of junctional rhythm). Resetting the pacemaker to a rate that inhibited spontaneous rhythm was effective in preventing TdP.

Electrocardiography↗
PubMed1996

Simple detection of xylosidase activity in single colonies, using 1-naphthyl-beta-D-xylopyranoside.

Since the xylosidase of Bacillus pumilus hydrolyzed 1-naphthyl-beta-D-xylopyranoside (naphthyl-X) to produce xylose and 1-naphthol and a chromogenic azo compound is produced by coupling 1-naphthol and Fast Blue Salt B, a simple method for detection of xylosidase activity in single colonies was studied. Escherichia coli JM109 carrying the xylosidase gene of B. pumilus was cultivated at 37 degrees C for 18 h on a LB plate containing 0.5 mg/ml naphthyl-X, and then the plate was overlaid with 3 ml of a top layer containing 24 mg of agar and 6 mg of Fast Blue Salt B. After incubation of the plate at 37 degrees C for 1 h, each colony became reddish-brown. Even a small colony with xylosidase on the plate was easily distinguished from colonies without the enzyme.

Bacillus↗
PubMed1996

Characterization of the feline herpesvirus type 1 immediate early gene expression.

We analyzed the mechanism for feline herpesvirus type 1 (FHV-1) immediate early (IE) gene expression. We demonstrated that (i) the transcription initiation site of the FHV-1 IE transcript lies in the putative FHV-1 ICP4 binding site, (ii) the FHV-1 IE transcript is spliced to remove 906 bp intron from the leader region, (iii) cis-acting elements of the FHV-1 IE promoter map both down- and upstream of the transcription initiation site, and (iv) a deletion of a 58 bp sequence which includes the putative FHV-1 ICP4 binding site in the IE promoter resulted in significant induction of promoter activity by a FHV-1 IE gene product although the FHV-1 IE gene product slightly stimulates the FHV-1 IE promoter, indicating that the FHV-1 IE gene product down-regulates its own promoter via the region.

Alphaherpesvirinae↗
PubMed1996

Detection of Marek's disease virus serotype 1 (MDV1) glycoprotein D in MDV1-infected chick embryo fibroblasts.

Chick embryo fibroblasts (CEFs) infected with three strains of Marek's disease virus serotype 1 (MDV1), GA, Md5 and JM, were subjected to indirect immunofluorescence assay with monoclonal antibodies (MAbs) against MDV1 homolog of glycoprotein D (MDV1 gD) of herpes simplex virus. By the MAbs, a number of MDV1 gD-positive cells were detected in CEFs infected with GA, whereas only a few and no positive cells were detected in CEFs infected with Md5 and JM, respectively. The MDV1 gD in GA-infected CEFs was recognized as the band of 64 kDa in immunoblot analysis using one of the MAbs. This is the first report that the MDV1 gD was detected in MDV1-infected cell cultures.

Animals↗
PubMed1996

Accumulation of albumin-linked and free-form pentosidine in the circulation of uremic patients with end-stage renal failure: renal implications in the pathophysiology of pentosidine.

Pentosidine is an advanced glycation end product and its formation is shown to be closely related to oxidative processes. Recent studies have shown that pentosidine levels are increased not only in plasma and matrix proteins from diabetic patients, but also markedly in nondiabetic hemodialysis patients. Currently, the mechanism of accumulation and kinetics of pentosidine formation in hemodialysis patients remain unknown. Gel filtration of uremic plasma revealed that plasma pentosidine exists in the albumin fraction (approximately 90%) and, interestingly, in free form (approximately 5%) as well. Plasma free pentosidine was undetectable in subjects with normal renal function. There was a significant correlation between the plasma levels of albumin-linked and free pentosidine in hemodialysis patients. Kinetic studies indicated that dietary pentosidine was absorbed into the circulation and that, after either oral or intravenous administration of pentosidine to intact or nephrectomized rats, the plasma free pentosidine level was closely linked to the level of renal function. These findings demonstrate that: (1) Pentosidine accumulates as albumin-linked and in free form in the circulation of uremic patients; (2) dietary pentosidine can be absorbed into the circulation, thus being one possible origin of circulating free pentosidine; (3) free pentosidine may accumulate as a result of decreased glomerular filtration; and (4) the mechanism of accumulation of albumin-linked pentosidine is not related to high glucose levels. It suggests the simultaneous accumulation, during renal failure, of either unknown pentosidine precursor(s) or catalyst(s) of glycoxidation, independent of glucose.

Animals↗
PubMed1996

Environmental health.

The rapid industrial development that began in the 1950's created environmental problems which consequently led to health hazards among residents of heavily polluted areas in Japan, such as Minamata Disease and Yokkaichi Asthma. Faced with these situations, the Japanese national government and local environmental authorities exerted much efforts to control pollution as well as to provide solutions to health problems. Many studies, including environmental epidemiology, have been conducted, aiming at determining relations between health problems and pollution. The results of environmental epidemiologic studies were prone to conclude associations with pollution and targeted health damages. In the case of the air-pollution related diseases, the government compensated individuals with non-specific respiratory diseases who are residents in the designated special high level air pollution areas. Epidemiological studies played an important role in designating pollution-related diseases and polluted areas.

Environmental Health↗
PubMed1996

Neuroendocrine mechanism mediating fasting-induced suppression of luteinizing hormone secretion in female rats.

Forty-eight hours fasting profoundly suppresses LH secretion in female rats. The following neural pathway mediating fasting-induced suppression of LH secretion has been suggested by a series of experiment: a signal associated with fasting emanating from the upper digestive tract reaches the A2 region in the medulla oblongata via afferent vagal nerve so as to activate the noradrenergic pathway projecting to the hypothalamic paraventricular nucleus (PVN); this results in an increased corticotropin-releasing hormone release to suppress LHRH release and then LH release. The PVN and A2 region of the medulla oblongata are the estrogen feedback sites to activate the above-mentioned neural pathway. The estrogen feedback action on the PVN and A2 region is considered to be due to an increased expression of estrogen receptors in these nuclei after 48-h fasting. The response of gonadal axis during fasting could be due to the changes in some nutrients, such as glucose and free-fatty acids. In this context, malnutrition could be a kind of stress accompanied by an increased feeding behavior and decreased gonadal activity.

Animals↗
PubMed1996

Overexpression of c-myc messenger RNA in primary and metastatic lesions of carcinoma of the stomach.

BACKGROUND: Although c-myc expression in carcinoma of the stomach has been reported to be involved in progression of the disease, little is known about the mechanism or significance of its expression. STUDY DESIGN: We measured c-myc messenger RNA (mRNA) levels by Northern blot hybridization in 51 primary gastric carcinoma lesions and 15 metastatic lesions accompanied by normal mucosal tissues from the same patients. The extent of c-myc mRNA expression in malignant lesions was determined and compared with that in normal mucosal tissues. The clinical and pathologic significance of c-myc mRNA expression was investigated. RESULTS: In 35 (68.6 percent) of 51 primary gastric carcinomas c-myc mRNA was overexpressed. Expression was found to be more frequent and stronger in early lesions than in advanced lesions (90 percent, 6.15-fold compared with 54.8 percent, 2.42-fold, p < 0.05). However, c-myc mRNA expression in the primary lesions showed little influence on either the histologic features or the disease progression. C-myc mRNA levels were higher in every metastatic lesion than in the primary lesions (9.89-fold compared with 3.04-fold, p < 0.05). CONCLUSIONS: These observations suggest that c-myc mRNA overexpression may play a role in the early development of primary lesions as well as in the formation of metastatic lesions of carcinomas of the stomach.

Blotting, Northern↗
PubMed1996

Arbutin: mechanism of its depigmenting action in human melanocyte culture.

Arbutin, a naturally occurring beta-D-glucopyranoside of hydroquinone, is effective in the topical treatment of various cutaneous hyperpigmentations characterized by hyperactive melanocyte function. We examined the mechanism of its depigmenting action in human melanocyte cultures. Arbutin inhibited the tyrosinase activity of cultured human melanocytes at noncytotoxic concentrations. It did not affect the expression of tyrosinase mRNA. Melanin production was inhibited significantly by arbutin, as determined by measuring eumelanin radicals with an electron spin resonance spectrometer. The study of the kinetics and mechanism for inhibition of tyrosinase confirms the reversibility of arbutin as a competitive inhibitor of this enzyme. The utilization of L-tyrosine or L-dopa as the substrate suggests a mechanism involving competition with arbutin for the L-tyrosine binding site at the active site of tyrosinase. These results suggest that the depigmenting mechanism of arbutin in humans involves inhibition of melanosomal tyrosinase activity, rather than suppression of the expression and synthesis of tyrosinase.

Arbutin↗
PubMed1996

[Correlation between expression of RB protein and prognosis of gastric cancer].

In this study, the expression of retinoblastoma (RB) protein was investigated immunohistochemically in 94 patients with gastric cancer. Overexpression of RB was detected in 48 tumors (51.1%). There was no significant association among the expression of RB, histologic type, lymph node metastasis, and liver metastasis. However, a significant difference was noted with respect to depth of invasion and peritoneal metastases. Among 94 patients, peritoneal metastases were observed in 11 patients. RB expression was detected in only two of these cases with peritoneal metastases, which was significantly less than those without peritoneal metastases. In relation to prognosis, patients with RB-positive tumors had a significantly better prognosis than those with RB-negative tumors. In conclusion, this study suggested that expression of RB has a prognostic value in gastric cancer.

Adenocarcinoma↗
PubMed1996

[Association between p53 expression and chemosensitivity in advanced and recurrent gastric cancer].

Fifteen cases with very advanced and recurrent gastric carcinoma were treated by 5-FU plus cisplatin. Among them, 6 cases were responder (CR + PR) and 9 cases were nonresponder (NC). In order to select the responder, p53 protein status in the tissue obtained by endoscopical biopsy before chemotherapy was studied. The immunohistochemical method was by the avidin-biotin complex method using anti-p53 protein monoclonal antibody. One CR case showed negative p53 staining and 2 of 5 cases of PR cases exhibited positive p53 staining. The staining of all 9 NC cases was positive. Significantly high p53 protein overexpression in the nonresponder cases was indicated. In conclusion, our result suggested that the immunohistochemical method detecting p53 protein in the biopsy specimen may be useful to predict the effect by chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

[Effects of gonadotropin-releasing hormone and its analogue (buserelin) on aromatase in cultured human granulosa cells].

We studied the direct effects of gonadotropin-releasing hormone (GnRH) and its analogue (buserelin) on aromatase activity and the aromatase cytochrome P-450 (P-450arom) concentration in cultured human granulosa cells which were obtained during oocyte retrieval for in vitro fertilization. Aromatase activity was assessed by radioassay with [1beta-3H]androstenedione as the substrate. The P-450arom concentration was determined by an enzyme-linked immunosorbent assay with specific antibodies to P-450arom. Buserelin stimulated aromatase activity and P-450arom at low concentrations (10(-13) - 10(-9)M), but it suppressed these parameters at high concentrations (10(-8) - 10(-7)M). The stimulatory effect increased with time during 12- to 48-h culture and disappeared after 72-h culture. Follicle-stimulating hormone (FSH) (100 ng/ml) stimulated aromatase activity and the P-450arom concentration but, FSH stimulation was suppressed by co-administration of low or high concentrations of buserelin. In contrast GnRH suppressed aromatase activity and P-450arom at all concentrations (10(-12) - 10(-6)M). GnRH also suppressed FSH stimulation of aromatase. Aromatase activity was correlated with the P-450arom concentration. These results suggest that in human preovulatory granulosa cells, buserelin and GnRH modulate aromatase activity by changing the P-450arom concentration.

Aromatase↗
PubMed1996

[Manifestation of the symptoms in demented patients after the Great Hanshin Earthquake in Japan].

On Jan. 17, 1995, at 5:46 a.m., an earthquake measuring 7.2 on the Richter scale shook southern area of Hyogo prefecture of Japan, including Kobe city. By this earthquake referred as the Great Hanshin Earthquake later, over 6,000 people were killed, 150,000 buildings and houses were destroyed and more than 300,000 people were temporally evacuated. Over a half of victims were reported to be elderly. We reported five survivors with senile dementia of the Alzheimer's type, who showed exacerbation or manifestation of their dementia symptoms after the quake. None of them had been injured and none of their close relatives had been killed or injured. They had been living in the downtown of Kobe for over 30 years before the disaster. Most of them had lived by themselves. Their severity of dementation were mild to moderate. They had been living without any problems and functioning fairly well. Their sons and daughters did not realize that their fathers or mothers had dementia before the earthquake. They had to move to and live with their son's or daughter's families, since their residences were destroyed by the earthquake. Shortly after that, they showed exacerbation or manifestation of their symptoms and developed delusion that their money and valuables were stolen by their daughters or daughters-in-law. We concluded that: they had been living without any problems and functioning fairly well, although they had had mild dementia symptoms; their living by themselves in communities familiar to them prevented manifestation of dementia symptoms; living together with son's or daughter's family easily promoted the development of delusion that their property was stolen by their close relatives, especially daughters or daughters-in-law in demented people.

Aged↗
PubMed1996

[Intraorbital conjunctival cyst after a penetrating orbital injury: a case report].

We report a case of intraorbital conjunctival cyst following a penetrating orbitocranial injury. The patient was a 28-year-old male who was hospitalized with exophthalmos, retrobulbar pain and upper gaze disturbance of his left eye. When he was 4 years old, a thin iron rod had penetrated intracranially through the inner angle of his left orbit. He was hospitalized and treated conservatively for about two weeks. The left eye ball was intact and visual acuity was normal, although bloody fluid had continuously flowed out from the left inner angle of the conjunctival wound for a few days. He had been febrile to 39 degrees C and complained of headache for one week. Subsequentry, the symptoms gradually improved through conservative therapy. When he was a junior high school student, he noticed exophthalmos of his left eye. However, he had never been examined closely, until he was 28 years old. We suspect that he had suffered from meningitis caused by the penetrating orbitocranial injury, and had fortunately improved under the conservative therapy. On admission to our hospital, a craniogram showed fracture of the left orbital roof, and coronal and three-dimensional computed tomography (CT) scans clearly demonstrated the orbital fracture. CT revealed a cystic mass in the retrobulbar space, and a porencephalic cyst in the medial basal frontal lobe. On magnetic resonance imaging (MRI) scans, both cysts were of low intensity on T1-weighted imaging, and of high intensity on T2-weighted images. Coronal and sagittal MRI scans showed that the two cysts were connected with each other through the fracture in the orbital roof. We diagnosed therefore that the orbital cyst was a herniated porencephalic cyst of the frontal lobe. Surgery was performed by a transcranial approach. The porencephalic cyst adhered to the fractured lesion of the frontal base but did not extend into the orbita. The intraorbital cyst was totally removed by opening the orbital roof including the fractured lesion. The cyst contained milky fluid. Postoperatively, the exophthalmos, retrobulbar pain and upper gaze disturbance showed gradual improvement. On histological examination, the cyst was found to be lined by non-keratinized stratified squamous epithelium and was diagnosed as a conjunctival cyst. This case was considered to be one of traumatic conjunctival cysts caused by a penetrating orbitocranial injury. Orbital conjunctival cysts have been reported to comprise about 10% of orbital epidermoid and dermoid cysts. Of these cysts, traumatic conjunctival cysts are rare, and only a few cases have been described. The etiology and therapy of orbital conjunctival cysts are discussed.

Adult↗