Biomedical subjects

A Tanaka

Publications and source records attributed to A Tanaka.

At least 415 records · Page 23Linked to original sources

PubMed1999

Cataract and retinal detachment in patients with severe atopic dermatitis who were withdrawn from the use of topical corticosteroid.

Many patients with severe atopic dermatitis (AD) in Japan are afflicted with persistent erythema of the face (atopic red face) that is not only resistant to topical corticosteroid, but often becomes worse with its use. During a three-year period (1991-1993), we treated 79 inpatients with severe AD by a combination of careful daily skin care, use of emollients, and exclusion of exacerbating factors. Occular complications before and after treatment were examined in these cases. After withdrawal of topical corticosteroid, almost all of the patients showed a temporary worsening of their skin condition. Immediately thereafter, their occular symptoms did not change. Cataract was found in 20 cases (25.3%), and retinal detachment in 9 (11.4%). After 2 months, 11 cases of cataract and 5 cases of retinal detachment in the peripheral retina were observed. However, these incidences were similar to the numbers reported in Japan during conventional treatment with topical corticosteroid. The development of cataract or retinal detachment had no relationship to serum IgE levels, personal history of respiratory atopy, the duration of topical corticosteroid use on the face, or treatment with systemic corticosteroid. Our observations suggest that patients who habitually tap or rub their faces strongly tend to develop cataract or retinal detachment at a statistically significant higher frequency. Patients with AD should have ophthalmologic examinations every one to two months for at least one year after a facial oozing attack or withdrawal of corticosteroid.

Administration, Topical↗

PubMed1999

An assessment of the role of Candida albicans antigen in atopic dermatitis.

An immediate hypersensitivity reaction to Candida albicans (C. albicans) antigen has been observed in patients with atopic dermatitis. Recent data from a comparative study of the immune response to C. albicans antigen in patients with atopic dermatitis and non-atopics suggest a shift form type 1 helper T cells to type 2 helper T cells in the immune response to C. albicans antigen in atopic dermatitis. To delineate the role of C. albicans in the pathogenesis in atopic dermatitis, we evaluated skin reaction of C. albicans antigen, as well as the serum IgE antibody level against C. albicans in patients with atopic dermatitis, patients with nasal allergy, and non-atopics. In addition, the clinical effect of antifungal drugs was evaluated in the patients with atopic dermatitis. As a result, we found that immediate hypersensitivity to C. albicans antigen is strongly correlated with the patients with atopic dermatitis. On the other hand, the delayed-type hypersensitivity to this antigen, which is highly prevalent in atopics without dermatitis as well as non-atopics, was reduced in most of these patients. Antifungal drugs markedly improved the skin manifestations in patients with atopic dermatitis that have IgE antibodies against C. albicans, and the serum IgE levels also decreased. These results suggest that C. albicans antigen is a potent intrinsic factor in inducing skin lesions in atopic dermatitis because of IgE-mediated hypersensitivity of C. albicans antigen.

Adolescent↗

PubMed1999

C-kit gene abnormalities in gastrointestinal stromal tumors (tumors of interstitial cells of Cajal.

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the GI tract, and expresses KIT and CD34 in most cases. Gain-of-function mutation of the c-kit proto-oncogene has been described, but its significance in GIST has not yet been fully evaluated. Mutation in exon 11 of the c-kit gene was determined by both polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing in primary and metastatic GISTs and esophageal leiomyomas in Japanese subjects. C-kit gene mutation was identified in 15 of 48 primary GISTs (31%), four of seven metastatic GISTs, but none of the leiomyomas. Three mutations were mis-sense point mutations, and 16 were in-frame deletions of 3-48 bp. C-kit gene mutation was observed equally in low- and high-risk groups, and was not related to any clinical and pathologic factors, phenotypes or Ki-67 labeling index (LI) of tumor cells. In five of 15 deletion mutations (four in primary tumors and one in a metastatic tumor), the mutations were present at the distal location of exon 11 of the c-kit gene, which was a minor mutation in previous reports from Finland and the USA. C-kit gene mutations in GIST are not always related to a poor prognosis, but further comparative studies are necessary in Western and Japanese populations.

Adult↗

PubMed1999

Exercise four hour redistribution thallium-201 single photon emission computed tomography and exercise induced ST segment elevation in detecting the viable myocardium in patients with acute myocardial infarction.

OBJECTIVE: To investigate the specificity and sensitivity of the combination of redistribution in exercise thallium-201 single photon emission computed tomography (SPECT) and exercise induced ST elevation for detecting the viable myocardium in patients with acute myocardial infarction. DESIGN: 37 patients were studied within seven weeks of onset of Q wave myocardial infarction (anterior in 22, inferior in 15). All patients underwent exercise four hour redistribution thallium-201 SPECT and positron emission tomography using fluorine-18-fluorodeoxyglucose (FDG) and nitrogen-13 ammonia under fasting conditions. RESULTS: Sixteen patients showed exercise induced ST elevation >/= 1.5 mm, and 15 of these had increased FDG uptake in the infarct region. Eleven of 16 patients (10 of 11 patients with anterior infarctions) with irreversible thallium-201 defects and increased FDG uptake showed exercise induced ST elevation. The sensitivity, specificity, and predictive accuracy of redistribution, exercise induced ST segment elevation, or both for detecting increased FDG uptake were 82%, 75%, and 67% (94%, 75%, and 91% for anterior infarctions), respectively. CONCLUSIONS: In patients with acute Q wave myocardial infarction, the combination of redistribution in exercise thallium-201 SPECT and exercise induced ST elevation can detect the viable myocardium in the infarct region with high sensitivity and specificity, especially in patients with anterior infarctions.

Adult↗

PubMed1999

Synchrotron microangiography reveals configurational changes and to-and-fro flow in intramyocardial vessels.

In 8 dogs, in situ microangiography using synchrotron radiation visualized penetrating transmural arteries (PTAs) with a diameter of >60 micrometers and allowed quantitation of vessel diameters of >140 micrometers. Myocardial contraction reduced the vascular short-axial diameters to 87 +/- 17% (n = 62, P < 0.001, paired t-test) of the end-diastolic values and increased the longitudinal dimension to 129 +/- 5% (n = 45, P < 0.001). The diameter reduction in the subendocardial PTA segments was significantly more marked than that in the subepicardial PTA segments (60 +/- 12 vs. 88 +/- 12%, n=13, P < 0.001, paired t-test). Intracoronary administration of dobutamine (0.1 micrograms. kg-1. min-1) increased, and in contrast, partial clamping of the coronary artery (ischemia) decreased, the configurational changes. To-and-fro blood flow was clearly observed in PTAs with visual identification of capacitive backflow, resistive forward flow during ischemia on coronary arteriography, and even under baseline conditions in coronary venography. Thus this method advances our understanding of mechanical influences on the coronary circulation.

Animals↗

PubMed1999

Branching patterns of intramural coronary vessels determined by microangiography using synchrotron radiation.

The intramural coronary artery (IMCA) with a diameter of 50-500 micrometers is critical for blood supply to the inner layers of heart muscle. We introduced digital measurement to microangiography using monochromatic synchrotron radiation and quantified branching patterns of the IMCA, the epicardial coronary artery (EPCA), and the distal ileal artery (DIA). The pre- and postbranching diameters were measured (95-1,275 micrometers) in seven dogs. A typical arterial segment divided into two nearly equivalent branches, and a regression line of daughter-to-mother diameter plots was almost identical among the EPCA (y = 0.838x - 16.7 in micrometers), IMCA (y = 0.737x - 2.18), and DIA (y = 0.755x + 8.63). However, a considerable difference was present at a segment where a proximal IMCA branched off from an EPCA (y = 0.182x + 90.2). Moreover, a proximal IMCA diameter had no relationship to the branching order from an EPCA. The precision of this method was confirmed by the good correlation of diameter measurements between two independent observers (r = 0.999, y = 1.02x - 1.07). In conclusion, using digital microangiography we demonstrated that the self-similar branching pattern of coronary arteries was discrete at the connection between the IMCA and EPCA.

Angiography↗

PubMed1999

Intramyocardial vascular volume distribution studied by synchrotron radiation-excited X-ray fluorescence.

We evaluated the vascular volume distribution with fine resolution (0.1-1.3 mg myocardial tissue) in the sagittal plane of the left ventricle by using the microsphere filling method in 21 dogs. The coronary arterial volume density in the sagittal plane did not exhibit normal distribution and was characterized by variability among the outer-to-inner layers and within the layers (+2SD/-2SD > 80 times), and the median values in the layers ranged from 4.7 to 22. 9 nl/mg myocardial tissue. The fractal analysis of vascular volume revealed a self-similar nature with a fractal dimension (D value) similar to that of flow distribution (1.20 +/- 0.05 and 1.24 +/- 0. 09 for vascular volume and flow distribution, respectively) and had a more marked variability than the flow. The correlation of the regional vascular volume between adjacent regions decreased as the distance increased. However, the correlation coefficients in the endocardial-to-epicardial direction were significantly higher than those in the anterior-to-posterior direction (P < 0.05 by paired t-test). In conclusion, we determined intramyocardial vascular volume density in the sagittal plane, and the distribution revealed considerable variability, self-similarity, and asymmetry in the correlation among the adjacent regions. These observations could be related to the characteristics of the intramural coronary vascular network.

Animals↗

PubMed1999

Impeding O(2) unloading in muscle delays oxygen uptake response to exercise onset in humans.

We tested whether the leftward shift of the oxygen dissociation curve of hemoglobin with hyperpnea delays the oxygen uptake (VO(2)) response to the onset of exercise. Six male subjects performed cycle ergometer exercise at a work rate corresponding to 80% of the ventilatory threshold (VT) VO(2) of each individual after 3 min of 20-W cycling under eupnea [control (Con) trial]. A hyperpnea procedure (minute ventilation = 60 l/min) was undertaken for 2 min before and during 80% VT exercise in hypocapnia (Hypo) and normocapnia (Normo) trials. In the Normo trial, the inspired CO(2) fraction was 3% to prevent hypocapnia. The subjects completed two repetitions of each trial. To determine the kinetic variables of VO(2) and heart rate (HR) at the onset of exercise, a nonlinear least-squares fitting was applied to the data averaged from two repetitions by a monoexponential model. The end-tidal CO(2) partial pressure before the onset of exercise was significantly lower in the Hypo trial than in the Con and Normo trials (22 +/- 1 vs. 38 +/- 3 and 36 +/- 1 mmHg, respectively, P < 0.05). The time constant of VO(2) and HR was significantly longer in the Normo trial (28 +/- 7 and 39 +/- 18 s, respectively) than in the Con trial (21 +/- 7, 34 +/- 16 s, respectively, P < 0.05). The VO(2) time constant of the Hypo trial (37 +/- 12 s) was significantly longer than that of the Normo trial, although no significant difference in the HR time constant was seen (Hypo, 41 +/- 28 s). These findings suggested that respiratory alkalosis delayed the kinetics of oxygen diffusion in active muscle as a result of the leftward shift of the oxygen dissociation curve of hemoglobin. This supports an important role for hemoglobin-O(2) offloading in setting the VO(2) kinetics at exercise onset.

Adult↗

PubMed1999

Small chronic hemorrhages and ischemic lesions in association with spontaneous intracerebral hematomas.

BACKGROUND AND PURPOSE: It has been speculated that the same type of hypertensive small-artery disease can cause either intracerebral hemorrhages or ischemic lesions, depending on the circumstances. METHODS: To test this hypothesis, we examined the association between spontaneous intracerebral hematomas and both small chronic hemorrhages and ischemic lesions using echo planar and T2-weighted MRI. We considered a hypointense area to represent a hemorrhage and a hyperintense area to represent an ischemic lesion. RESULTS: We identified small hypointense lesions in 56.7% of 30 patients with intracerebral hematomas (mean age, 62.2 years; total number of lesions, 108) and in 25.4% of 59 patients without hematomas (mean age, 67.6 years; total lesions, 28). The incidence of hypertension was 88.3% in patients with intracerebral hematomas and 42.3% in those without. The hypointense lesions were found in 56.0% of 50 patients with hypertension, whereas they were found only in 10.3% of 39 patients without hypertension. The hypointense lesions were most common in the subcortex, followed by the putamen, pons, thalamus, and cerebellum. The hyperintense lesions were of a higher grade in patients with intracerebral hematomas than in those without. The hypointense lesions were commonly surrounded by hyperintense areas. Additionally, in 3 of 3 autopsied brains, we found hemosiderin deposits around arteriosclerotic microvessels and a surrounding small infarction in areas that had appeared as small hypointense lesions surrounded by hyperintensity on MRI. One specimen also had an organized miliary pseudoaneurysm. CONCLUSIONS: Our findings indicate that spontaneous intracerebral hematomas are frequently associated with small chronic hemorrhages, ischemic lesions, and hypertension. We speculate that hypertensive intracerebral hemorrhage may have the same microangiopathic basis as cerebral infarction.

Adult↗

PubMed1999

Collapsibility of passive pharynx in patients with acromegaly.

Sleep-disordered breathing (SDB), either central or obstructive in nature, is common in patients with acromegaly. However, no study has systematically examined the collapsibility of the pharynx in acromegaly to date. We evaluated intrinsic mechanical properties of passive pharynx in 10 anesthetized and paralyzed patients with active acromegaly before transsphenoidal adenomectomy for their pituitary adenoma. Static pressure-area relationships of the velopharynx and oropharynx were obtained by step changes in airway pressure during endoscopic cross-sectional area measurement of each segment. Moreover, curve fitting analysis by an exponential function estimated the closing pressure (P'close) of each segment. Preoperative nocturnal oximetry identified five acromegalic patients with an oxygen desaturation index (ODI) greater than 10 h-1 and clinical symptoms suggesting presence of SDB. The pharyngeal airway of all five acromegalic patients with SDB was highly collapsible at both velopharynx and oropharynx with positive P'close. Compared with age-, body mass index (BMI)-, and ODI-matched SDB patients without acromegaly, SDB patients with acromegaly had a higher P'close of the oropharynx, indicating that the etiology of SDB in acromegaly appears to differ from that of ordinary sleep apnea. Our results suggest that anatomic abnormality, especially at the base of the tongue, appears to play a significant role in development of SDB in acromegaly.

Acromegaly↗

PubMed1999

Decrease of serum levels of soluble CD23 during immunotherapy in patients with perennial allergic rhinitis.

There is increasing in vitro evidence that soluble CD23 (sCD23) is capable of potentiating the synthesis of human IgE and is likely involved in the expression of allergic diseases. Our study has aimed at investigating whether serum sCD23 is elevated in patients with perennial allergic rhinitis as compared to nonatopic controls, whether sCD23 in perennial allergic rhinitis fluctuates during the natural course in untreated patients, and whether sCD23 is decreased by immunotherapy. This study included 139 patients with perennial allergic rhinitis due to Dermatophagoides farinae who gave informed consent to participation. They were divided into 2 groups--an untreated group and an immunotherapy group--according to their treatment background. Thirty-one nonallergic, healthy volunteers were included to serve as controls. Symptom scores and serum concentrations of IgE specific to D. farinae and sCD23 were examined twice in each patient: at enrollment (first evaluation) and on a variant time course after enrollment (second evaluation). Serum concentrations of sCD23 were measured by a sandwich enzyme-linked immunosorbent assay. The level of sCD23 in patients with perennial allergic rhinitis was significantly higher than that in nonatopic controls (p < .0001). The level of sCD23 in perennial allergic rhinitis was correlated with the level of specific IgE against D. farinae. The sCD23 level did not fluctuate during the natural course for a span of 2.8 +/- 2.7 years in untreated patients (p = .1337), but was significantly decreased in patients who received immunotherapy for 2.7 +/- 2.2 years (p < .0001). The rate of decrease in sCD23 was significantly correlated with the rate of decrease in specific IgE (rs = .523, p < .0001) and symptom scores (rs = .450, p < .0001). In conclusion, the reduction in sCD23 during immunotherapy is probably related to the decrease in specific IgE and also plays a role in mediating its clinical effect.

Adult↗

PubMed1999

Effects of tongue electrical stimulation on pharyngeal mechanics in anaesthetized patients with obstructive sleep apnoea.

The tongue plays a significant role in the maintenance of a patent airway. The purpose of this study was to examine the effects of tongue musculature contraction on the static mechanical properties of the pharynx in patients with obstructive sleep apnoea (OSA). During hyperventilation-induced apnoea in seven OSA patients anaesthetized with sevoflurane, the static pressure/area relationships of the oropharynx were obtained by means of step changes in airway pressure while endoscopically measuring cross-sectional area. At each airway pressure, the tongue was electrically stimulated via electrodes placed bilaterally. Tongue electrical stimulation (TES) did not further dilate the oropharyngeal area at higher airway pressure (3.2+/-1.9 versus 3.0+/-2.1 cm2), although the narrowed oropharyngeal area at lower airway pressures increased during TES (0.8+/-9.0) versus 1.7+/-1.8 cm2, p<0.05). Accordingly, the slope of the pressure/area relationship decreased during TES (0.24+/-0.20 versus 0.12+/-0.09 cm2 x cm H2O(-1), p<0.05). In conclusion, electrical stimulation of the tongue stiffens the retroglossal airway wall in patients with obstructive sleep apnoea.

Adult↗

PubMed1999

Fasting remnant lipoprotein cholesterol and triglyceride concentrations are elevated in nondiabetic, insulin-resistant, female volunteers.

This study was initiated to test the hypothesis that plasma concentrations of remnant lipoproteins would be higher after an overnight fast in insulin-resistant compared to insulin-sensitive volunteers. Forty-three healthy nonobese women were studied, divided into insulin-resistant (n = 21) and insulin-sensitive (n = 22) groups on the basis of their steady state plasma glucose (SSPG) concentration at the end of a 180-min infusion of octreotide acetate, insulin, and glucose. Under these conditions, steady state plasma insulin concentrations are similar in all subjects (approximately 60 microU/mL), and the higher the SSPG concentrations, the more insulin resistant the individual. By selection, mean (+/-SEM) SSPG concentrations were significantly higher (P < 0.001) in the insulin-resistant group (210 +/- 7 vs. 78 +/- 3 mg/dL). In addition, the insulin-resistant group had higher triglycerides (198 +/- 27 vs. 101 +/- 12 mg/dL; P < 0.005) and lower high density lipoprotein cholesterol (48 +/- 4 vs. 60 +/- 4 mg/dL; P < 0.05) concentrations. Finally, insulin resistance was associated with higher remnant lipoprotein particle concentrations of cholesterol (7.2 +/- 0.8 vs. 4.4 +/- 0.3; P < 0.005) and triglycerides (22.2 +/- 3.4 vs. 8.5 +/- 1.0; P < 0.001). All of these differences were seen despite the fact that the two groups were similar in terms of age and body mass index. These results identify additional abnormalities in lipoprotein metabolism that may contribute to the increased risk of coronary heart disease seen in insulin-resistant, nondiabetic subjects (syndrome X).

Blood Glucose↗

PubMed1999

Nonpeptide arginine vasopressin antagonists for both V1A and V2 receptors: synthesis and pharmacological properties of 4'-[5-(substituted methylidene)-2,3,4,5-tetrahydro-1H-1-ben zoazepine-1-carbonyl]benzanilide and 4'-[5-(substituted methyl)-2,3-dihydro-1H-1-benzoazepine-1- carbonyl]benzanilide derivatives.

Arginine vasopressin (AVP) has a dual action, i.e. vasoconstriction and water reabsorption via V1A and V2 receptors, and may play a role in a number of diseases, including congestive heart failure (CHF), hypertension, renal disease, edema, and hyponatremia. We have attempted to develop a new series of AVP antagonists for both V1A and V2 receptors based on the hypothesis that the blockade of both V1A and V2 receptors might be beneficial to CHF patients. In this report, a series of compounds structurally related to 4'-[5-(substituted methylidene)-2,3,4,5-tetrahydro-1H-1-benzoazepine-1-carbonyl ]benzanilide (exo-olefin isomer) and 4'-[5-(substituted methyl)-2,3-dihydro-1H-1-benzoazepine-1-carbonyl]benzanilide (endo-olefin isomer) were synthesized and examined to have AVP antagonist activity for both V1A and V2 receptors. As a result, it was found that the (E)-exo-olefin isomers showed more potent binding affinity compared with endo-olefin isomers. Among these (E)-exo-olefin isomers, (E)-N-methyl-{1-[4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tetrahyd ro-1H-1 -benzoazepin-5-ylidene}acetamide (14) exhibited the most potent binding affinity and (E)-N-methyl-(1-{4-[2-(4-methylphenyl)benzoylamino]benzoyl}-2,3,4,5- tetrahydro-1H-1-benzoazepin-5-ylidene)acetamide (20) exhibited a high AVP antagonist activity for both V1A and V2 receptors after intravenous administration. Details of the synthesis and pharmacological properties of this series are presented.

Animals↗

PubMed1999

Topology effect for DNA structure of cisplatin: topological transformation of cisplatin-closed circular DNA adducts by DNA topoisomerase I.

The reaction of cis-Pt(NH3)2Cl2(cis-DDP)-closed circular DNA adducts with DNA topoisomerse I(topo I) were studied by electron microscopy. We identified unique topoisomers such as a singly-linked catenane (2(1)2), trefoil (3(1), and dimetric catenane (2(1)2), etc., by analysis with electron micrographs. These unique recombination products resulted from cis-DDP-intra-twisting looped DNA adducts by DNA topo I, and the products could be explained a new mechanism based on an odd-even number rule. Our results suggest a new model on the working mechanisms for DNA topology of cis-DDP which enhances the recombination of DNA. Based on our results, we propose the topological idea that the yields of a mini closed circular DNA and pseudo trefoil DNA, etc., can be expected by reaction of cis-DDP-DNA-histone complexes with DNA topo I in the body.

Antineoplastic Agents↗

PubMed1999

Isolated primary chylopericardium.

A 16-year-old man was found to have an enlarged cardiac silhouette. Primary chylopericardium was diagnosed when pericardiocentesis yielded the characteristic milky-white fluid. The thoracic duct was easily identified by giving milk and butter and an injection of ethylene blue immediately before the operation. Intraoperative thoracic ductography showed no abnormal findings. Mass ligation of the thoracic duct above the diaphragm and partial pericardiectomy were successfully performed through a right thoracotomy approach. In addition, many of the lymphatics were ligated above the diaphragm. The right thoracotomy approach was a useful method for resection and ligation of the thoracic duct just above the diaphragm. Follow-up showed no accumulation of pericardial fluid or pleural effusion.

Adolescent↗

PubMed1999

[Pharmacology of conivaptan hydrochloride (YM087), a novel vasopressin V1A/V2 receptor antagonist].

Pharmacology of conivaptan hydrochloride (YM087) was investigated in in vitro and in vivo studies. In radioligand binding study, YM087 showed high affinity for both V1A and V2 receptors in animal and human species. Affinity of YM087 for V1A and V2 receptors was comparable to that of vasopressin (AVP). In functional antagonistic activity study, YM087 concentration-dependently inhibited AVP-induced intracellular Ca2+ elevation via human V1A receptors and AVP-stimulated cAMP accumulation via human V2 receptors. Intravenous administration of YM087 dose-dependently inhibited AVP-induced pressor responses and produced a dose-dependent aquaresis in rats and dogs. Oral administration of YM087 showed a potent and long-lasting antagonistic activity on V1A and V2 receptors. YM087 was effective in dogs with heart failure and in heart failure rats with hyponatremia and edema. These results reveal that YM087 is the first orally active V1A/V2 receptor antagonist and suggest that YM087 may be useful in the treatment of congestive heart failure and hyponatremia.

Animals↗

PubMed1999

Steady-state inhibitory kinetic studies on the ligand binding modes of Aspergillus niger glucoamylase.

Inhibitory activities of 1-deoxynojirimycin and gluconolactone on Aspergillus niger glucoamylase were studied in relation to the subsite structure of the enzyme. Although both of these inhibitors are considered to bind at subsite 1 of the enzyme active site, 1-deoxynojirimycin showed competitive type inhibition but gluconolactone was a mixed type (or noncompetitive type) inhibitor for the hydrolysis of p-nitrophenyl alpha-D-glucoside. The former type of inhibition suggested that the main binding mode of the substrate was productive, but the latter, nonproductive. A possible way of explaining these apparent inconsistent results is to assume that the main binding mode of the substrate is productive and gluconolactone forms a nonproductive ternary complex with the enzyme and the substrate.

1-Deoxynojirimycin↗