Biomedical subjects

M Akagi

Publications and source records attributed to M Akagi.

At least 109 records · Page 6Linked to original sources

PubMed1990

Sharpness and amplitude envelopes of broadband noise.

This paper discusses how amplitude envelope shapes, sound-pressure level, and duration of broadband noise affect sharpness and brightness. In the first experiment, sharpness, brightness, and similarity were judged for paired stimuli by 13 subjects. The stimuli consisted of broadband noise with different types of amplitude envelopes, sound-pressure levels, and duration. Experimental results were analyzed with a multidimensional scaling technique. In addition, the second experiment measuring the point of subjective equality (PSE) of sharpness was carried out for four subjects. The results of these two experiments showed large individual differences in sharpness judgment, difficulty in brightness judgment for the stimuli used in the experiments, and influence of the amplitude envelope shapes on sharpness. The individual differences observed in sharpness judgment were explained by the differences between weights given to two psychological dimensions: loudness and subjective duration. This study forms a basis for understanding sharpness of nonsteady sounds.

Acoustic Stimulation↗

PubMed1990

Evaluation of a spectrum target prediction model in speech perception.

A model of a spectrum target prediction mechanism is proposed and evaluated by comparing predicted values with results of psychoacoustic experiments. When the trajectory of the cepstrally smoothed LPC spectrum is approximated by a second-order critically damped system, the proposed model can estimate target values using short-period spectrum sequences (50 ms) without being given the onset positions of the spectral transition. Additionally, this model decreases the length of transitional sounds and recovers vowel characteristics neutralized by coarticulation. Moreover, this model compensates for the transitions of syllables and extracts stable characteristics from syllable transitions. This model is applicable to coarticulation recovery in speech signal processing.

Humans↗

PubMed1990

Anti-platelet activating factor, anti-leukotriene D4 and some other antiallergic activities of mequitazine.

The bronchoconstrictions of guinea pigs elicited in vivo by leukotriene D4 (LTD4) and platelet activating factor (PAF) were inhibited by pretreatment with mequitazine (CAS 29216-28-2) (p.o.) in a dose-dependent manner at doses of 5-20 mg/kg. Mequitazine (0.5-50 nmol/l) also inhibited LTD4- and PAF- induced contractions of guinea pig tracheal chain. These results suggest that mequitazine possesses antagonistic activity for LTs and PAF; the effects of mequitazine against these two agonists were much more potent than those of ketotifen. The histamine release induced by either of compound 48/80, concanavalin A or A23187 was inhibited by mequitazine at concentrations ranging from 1 to 20 mumols/l. In the inhibition process, mequitazine may act not only to inhibit the Ca2+ release from intracellular Ca store of mast cells but also to stabilize the lipid bilayer of the cell membrane as shown in the order parameter and hypotonic hemolysis. From the present study, it was assumed that mequitazine may exert antiallergic activity by antagonizing LTs and PAF as well as by inhibiting histamine release from mast cells.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1990

Antiallergic effects of astemizole on immediate type hypersensitivity reactions.

Astemizole (0.5-5 mg/kg, p.o.) dose-dependently inhibited heterologous and homologous PCA reactions in rats at ID50 values of 1.48 mg/kg and 2.37 mg/kg, respectively. The inhibitory effect of astemizole on heterologous PCA was most remarkable when this compound was given p.o. 2 h prior to antigen challenge. Astemizole (0.1-5 mg/kg, p.o.) dose-dependently inhibited experimentally-induced asthma in guinea pigs at an ID50 of 0.86 mg/kg. Ex vivo, astemizole (0.5-5 mg/kg, p.o.) inhibited antigen-induced histamine release from lung pieces of sensitized guinea pigs. In in vitro experiments, the drug dose-dependently inhibited antigen-induced histamine and SRS-A releases from guinea pig lung pieces at concentrations of 0.05-10 microM. Furthermore, astemizole (0.1-10 microM) inhibited the histamine release induced by compound 48/80 and antigen-antibody reaction from rat peritoneal mast cells, and at 0.1-500 nM inhibited both leukotriene C4- and platelet-activating factor (PAF)-induced contraction of isolated guinea pig trachea at submicromolar concentrations. Astemizole not only inhibited 45Ca uptake into rat mast cells but also prevented the Ca2+ release from the intracellular Ca store induced by compound 48/80, although this compound did not affect the histamine release from permeabilized mast cells induced by Ca2+. Our results suggest that one of the antiallergic mechanisms of astemizole may be an inhibition of signal transduction from the mast cell membrane to the intracellular systems.

Airway Resistance↗

PubMed1990

[A case of multiple tumors].

A 54-year-old man was admitted to our clinic for a further examination of rectal and liver tumors, after which a rectal cancer, a hepatocellular carcinoma (HCC), a hemangioma of the liver a retroperitoneal cyst, and a submucosal tumor of the stomach (SMT) were diagnosed by means of a colonoscopy, a gastroscopy, and US, CT, and angiography, these tests also revealing elevated CEA and AFP levels. A hepatic subsegmentectomy and a Miles's operation, as well as an enucleation of other liver tumors and an SMT, were performed and a retroperitoneal cyst was removed. The histopathological finding of the rectal cancer was a moderately differentiated adenocarcinoma, while the liver tumors were determined as being an HCC of the trabecular type, adenomatas revealing hyperplasia, a hemangioma, and the SMT showing a benign leiomyoblastoma.

Adenocarcinoma↗

PubMed1990

[Subtotal cor triatrium with left partial anomalous pulmonary venous connection--successful correction in an infant].

This report concerns a 10-month-old infant with subtotal cor triatrium associated with left sided partial anomalous pulmonary venous connection to the innominate vein. In the operation, we found that the fossa ovalis existed between the right atrium and the accessory atrial chamber. We performed a radical operation which consisted of a resection of the intra-left-atrial diaphragma and a anastomosis of the vertical vein to the left atrium. His postoperative course was uneventful, and the result was satisfactory. We have presented and reviewed our case, and then discussed the embryogenesis and the hemodynamics. To our knowledge, our case represents the first successful surgical repair of this combination of defects in Japan.

Brachiocephalic Veins↗

PubMed1989

A 2-deoxyribonolactone-containing nucleotide: isolation and characterization of the alkali-sensitive photoproduct of the trideoxyribonucleotide d(ApCpA).

It has been reported that ACA sequences in DNA are mutagenic hot spots in UV-induced mutagenesis and are sites of an alkali-sensitive lesion produced by UV irradiation. In order to characterize the UV-induced lesion of an ACA site, chemically synthesized trideoxyribonucleotide d(ApCpA) was irradiated with UV light and the alkali-sensitive photoproduct was isolated. The structure of this photoproduct was characterized as the trinucleotide containing 2-deoxyribonolactone at the internal residue by 2D DQF-COSY, FT-IR, FAB-MS, and chemical properties. It is known that this lesion is also produced by gamma-irradiation, neocarzinostatin, the 1,10-phenanthroline-copper complex, and hydrogen peroxide and is highly mutagenic because of its resistance to cleavage by certain apurinic/apyrimidinic (AP) endonucleases. Thus, 2-deoxyribonolactone may be one of the lethal DNA lesions induced by UV irradiation to organisms and one of the intermediates of UV-induced DNA strand breaks because the DNA strand is cleaved at this site with beta- and subsequent delta-elimination mechanisms.

Base Composition↗

PubMed1989

Transcatheter arterial chemoembolization therapy for hepatocellular carcinoma using polylactic acid microspheres containing aclarubicin hydrochloride.

Transcatheter arterial chemoembolization therapy using polylactic acid microspheres containing aclarubicin hydrochloride (ACR) was performed in 62 patients with primary hepatocellular carcinoma. These microspheres were about 200 microns in diameter and contained 10% (w/w) aclarubicin. A single dose of polylactic acid microspheres containing ACR (50-100 mg of ACR) was administered 1 to 8 times with a mean of 2.2 doses (a total of 160 treatments) in 62 patients. Antitumor effects were observed from the decrease in serum alpha-fetoprotein levels (82.1% of the patients) and in two dimensional size of tumor on computed tomography (93.6%). The cumulative survival rate was 54.3% at 1 year, 24.6% at 2 years, and 19.2% at 3 years, respectively, among 59 patients with unresectable tumors. In 3 resected liver specimens, there was a significant accumulation of ACR in the tumor, and severe necroses of the tumors were observed histologically. Systemic toxicity was mild and all patients tolerated this treatment. These results suggest that transcatheter arterial chemoembolization with the use of polylactic acid microspheres containing ACR is a useful tumor-targeting chemotherapy and is effective in the treatment of hepatocellular carcinoma.

Aclarubicin↗

PubMed1989

Mechanism of the reversal reaction of platinated DNA with thiourea studied by platinated 5'-GMP.

The reversal reactions of cis-[Pt(NH3)2(5'-GMP)2] 2-(1) and trans-[Pt(NH3)2(5'-GMP)2] 2-(2) with thiourea were examined by reversed phase HPLC and monothioureido intermediate cis-[Pt(NH3)2(5'-GMP) (tu)] (4) was detected. This result suggested that Pt-[5'-GMP-N(7)] bond was more labile than Pt-NH3 bond and the release of ammonia from cis-Pt(II)-DNA base complexes is a result of trans-labilizing effect of sulfur containing molecule displaced with DNA base.

Ammonia↗

PubMed1989

Intracellular accumulation of cholesteryl esters suppresses production of lipopolysaccharide-induced interleukin 1 by rat peritoneal macrophages.

Interleukin 1 (IL-1) is a major cytokine of macrophages secreted by several stimulants such as lipopolysaccharide (LPS). Macrophages are known to possess the scavenger receptor for acetylated low density lipoprotein (acetyl-LDL) and maleylated albumin. In the present study we determined effects of these ligands on LPS-induced IL-1 production by rat peritoneal macrophages. These ligands themselves did not induce IL-1 production. However, upon short incubation with acetyl-LDL, LPS-induced IL-1 production was significantly suppressed. The extent of the suppression was proportional to cellular cholesteryl esters. Thus, intracellular accumulation of cholesteryl esters might be responsible for suppression of LPS-induced IL-1 production.

Albumins↗

PubMed1989

Serial ultrasonic examination to differentiate biliary atresia from neonatal hepatitis--special reference to changes in size of the gallbladder.

We performed serial ultrasonic examinations to differentiate biliary atresia from neonatal hepatitis. The subjects studied were 144 children (100 normal neonates and infants, 31 patients with neonatal hepatitis and 13 patients with biliary atresia). They were examined by ultrasound before, during and after feeding. In 97 out of 100 normal children and all patients with neonatal hepatitis, the gallbladder was identified, and the change in size following oral feeding was observed. In four children with severe neonatal hepatitis which could not be differentiated from biliary atresia by clinical and laboratory data, we readily identified the gallbladder and observed the change in the size following oral feeding. In 8 of 13 patients with biliary atresia, we identified a small gallbladder whose size was not affected by oral feeding. In the other patients the gallbladder was not identified before, during or after oral feeding. On the basis of these results, we consider that serial ultrasonic examination with oral feeding aids in a differential diagnosis of biliary atresia and neonatal hepatitis.

Biliary Atresia↗

PubMed1989

Definition of carcinoma of the gastric cardia.

This study concerns the definition of carcinoma of the gastric cardia. The topography of the esophagogastric mucosal junction (mucosal EGJ) was investigated with an endoscope in 182 patients who were free of hiatal hernias, ulcers, and neoplasms in the esophagus and stomach. The relationship between the EGJ and the cardiac gland area was then examined histologically in 56 resected specimens containing intact EGJs and cardia gland areas. Furthermore the cancerous center was determined; the shortest distance between the cancerous center and the EGJ and the amount of esophageal invasion were measured in 102 resected carcinomas located close to the junction; the carcinomas contained the EGJ and were good enough for pathohistological examination. The EGJ was located 0.5 - 1.0 cm proximal to the His angle (the gastric cardia) in radiological and endoscopic examinations. Histologically the cardiac gland area was found to straddle the EGJ at a range of about 1 cm proximal and 2 cm distal to the junction. Among the upper stomach carcinomas, most of the tumors (87.5%) whose center was located within 2 cm from the EGJ invaded the esophagus. In conclusion, carcinoma of the gastric cardia is defined as a lesion with its center located within 1 cm proximal and 2 cm distal to the EGJ.

Adolescent↗

PubMed1989

Radiation and surgical stress induce a significant impairment in cellular immunity in patients with esophageal cancer.

The effects of preoperative radiation plus surgical stress on immunity were examined in 29 patients with esophageal cancer, including 14 patients who experienced radiation therapy and 15 who did not, as well as 15 age-, sex- and body weight-matched control subjects. Absolute numbers of the total lymphocytes and OKT3 (all T cells), OKT4 (helper/inducer T cells) and OKT8 (suppressor/cytotoxic T cells) positive lymphocytes were almost the same in both patient groups before treatment. Both the in vitro response to phytohemagglutinin (PHA) and antibody dependent cell-mediated cytotoxicity (ADCC) were depressed in the patients when compared to the controls before treatment. Dual treatment of radiation and surgery led to a marked reduction of lymphocytes in the numbers and activities of PHA and ADCC, when compared to findings in the non-radiation group. Especially, the number of OKT4 positive lymphocytes and the OKT4 to OKT8 ratio decreased most and recovery was slow. While ADCC activity in the non-radiation group recovered at 28 postoperative days (POD), the response to PHA did not return to the pretreatment levels. Serum levels of IgG, IgM and IgA were within normal limits throughout the course of treatment. The B1 (all B cells) positive lymphocytes significantly decreased after the treatments. These results suggest that radiation plus surgery shifts the host immunity toward immunosuppression and induces a significant impairment of cellular immunity in patients with esophageal cancer.

Aged↗

PubMed1989

Adenofibromyomatous hyperplasia of the extrahepatic bile duct--a report of two cases.

Two patients with adenofibromyomatous hyperplasia located at the distal end of the extrahepatic bile duct are reported herein. The chief symptom in both patients was upper abdominal pain and the lesions found involved the proliferation of submucosal mucous glands and fibrous elements. Further progress in imaging diagnostic techniques would increase the frequency with which such lesions are discovered. But, even now, if mural irregularities and shadow defects are found in the extrahepatic bile duct, particularly in the distal end of the common bile duct, the possibility of a benign lesion such as adenofibromyomatous hyperplasia should be taken into consideration when making a diagnosis.

Adenofibroma↗

PubMed1989

Postoperative results of distal partial gastrectomy, selective vagotomy plus antrectomy, and selective proximal vagotomy for duodenal ulcers.

We investigated the postoperative results of distal partial gastrectomy, selective vagotomy plus antrectomy, and selective proximal vagotomy, to evaluate their effectiveness in the treatment of duodenal ulcers. The operative mortality of selective vagotomy plus antrectomy and selective proximal vagotomy seemed to be lower when compared to distal partial gastrectomy, although each procedure showed a sufficiently low mortality. The acid reduction rate was significantly lower after selective proximal vagotomy than after the other procedures (p less than 0.01). However, the rate of ulcer recurrence following selective proximal vagotomy tended to be higher compared with the other procedures. All three procedures showed good results according to Visick's grading and postoperative symptoms occurred in about 50 per cent of all patients, no matter what the procedure. The regaining of physical ability was significantly greater following selective proximal vagotomy than following distal partial gastrectomy (p less than 0.05) and the capacity to work was also better after vagotomy, particularly selective vagotomy plus antrectomy (p less than 0.05). Thus, although distal partial gastrectomy and selective vagotomy plus antrectomy proved superior regarding the low ulcer recurrence rate and acid reduction, while selective proximal vagotomy proved superior for improving the quality of life, on the whole, the three operations promise almost equivalent results.

Adult↗

PubMed1989

Quantitative electron microscopic study on grades of atypia in adenomas of the human large bowel.

Clarification of the ultrastructural features of the three different grades of histologic atypia of adenomas (i.e., mild, moderate, and severe atypia) with reference to carcinoma of the human colon and rectum was undertaken using electron microscopic quantitative analysis. Ten normal epithelia, 36 adenomas (14 with mild atypia, 13 with moderate atypia, and 9 with severe atypia) and 14 carcinomas (well-differentiated adenocarcinoma) were examined with light and electron microscopes. Although it has been generally accepted that malignant transformation of an adenoma gradually proceeds with increasing atypia, using light microscopy, ultrastructural quantitative analysis clearly revealed that fine features of individual atypia did not correspond with histologic grades of atypia. Ultrastructural changes occurred abruptly in moderate atypia and showed similar cellular characteristics to carcinoma cells. Mild atypia was almost similar in appearance to normal epithelial cells. Striking changes in the moderate atypic cells were plane apposition of the cell membrane, decrease of the desmosomes, and increase of the lysosomes. These atypical cells were assumed to play a significant role in the adenoma-carcinoma sequence. Therefore, radical surgical therapy would be required for moderate atypic adenoma of the large bowel that is difficult to remove endoscopically.

Adenocarcinoma↗

PubMed1989

Inhibition of stress-induced gastric injury in the rat by glutathione.

Glutathione metabolism occurs via interorgan cycles in which hepatic synthesis of reduced glutathione and its transfer to extrahepatic tissues play an important role. To elucidate the physiologic significance of the cycles and tissue thiol status during stress-induced gastric mucosal injury, dynamic aspects of glutathione metabolism were analyzed in rats that were treated with water-immersion restraint. This treatment induced gastric mucosal lesion with concomitant decrease in the levels of perchloric acid-soluble thiols in various tissues, particularly in the liver and stomach. During the treatment, glutathione levels markedly decreased in the liver but not in other tissues. Depletion of hepatic glutathione by buthionine sulfoximine, a specific inhibitor for gamma-glutamyl cysteine synthetase, markedly decreased hepatic glutathione levels and increased the gastric injury. Intraperitoneal injection of reduced glutathione significantly increased plasma levels of glutathione and inhibited the occurrence of gastric injury without affecting intracellular glutathione levels. These results indicate that extracellular glutathione and its interorgan metabolism might play a critical role in the protection of gastric mucosa particularly when animals were challenged with various stress.

Acetylcysteine↗

PubMed1989

Partial purification and characterization of CA19-9 antigen from the ascitic fluid of a patient with pancreatic cancer.

CA19-9 immunoreactive protein was partially purified from the ascitic fluid of a patient with pancreatic cancer by perchloric acid fractionation, gel chromatography and Affi-gel Blue column chromatography, resulting in a purified sample of 5.0 x 10(6) CA19-9 units per milligram of protein (3700-fold purification). Western blotting analysis of this purified sample revealed a single band of molecular weight 210 kDa. Although the original ascitic fluid showed a high CA125 immunoreactivity, this purified sample had no CA125 immunoreactivity. The elution pattern for CA19-9 activity on Affi-gel Blue column is quite distinct from that for CA125. These results suggest that CA19-9 antigen in carcinoma patients may be identical or very similar to that recently purified from the culture media of the colorectal cell line SW1116 and is distinct from CA125 antigen.

Antigens, Tumor-Associated, Carbohydrate↗