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Biomedical subjects

N Yamada

Publications and source records attributed to N Yamada.

At least 379 records · Page 21Linked to original sources
PubMed1996

Intracranial calcification on gradient-echo phase image: depiction of diamagnetic susceptibility.

PURPOSE: To differentiate calcification from hemorrhage on the basis of susceptibility at magnetic resonance imaging. MATERIALS AND METHODS: Gradient-recalled echo (GRE) phase imaging was performed at 1.5 T in 101 calcified areas (15 in the basal ganglia, 86 out of the basal ganglia) and 39 uncalcified locations (13 choroid plexus and pineal glands, 26 old hemorrhages). Experiments with a small lead particle and a numerical simulation were also performed. RESULTS: The majority of calcifications outside the basal ganglia (n = 63) revealed a phase shift that represents diamagnetic susceptibility and was similar to the phase shift in the lead particle and to the calculated phase shift for a diamagnetic sphere. All hemorrhages and almost all calcified basal ganglia revealed a phase shift that represents paramagnetic susceptibility. All uncalcified choroid plexus and pineal glands revealed no obvious phase shift. Any location without calcification did not reveal the diamagnetic phase shift. CONCLUSION: GRE phase imaging differentiated paramagnetic from diamagnetic susceptibility, which was specific for calcification.

Aged↗
PubMed1996

Scanning electron microscopy of the basal surface of the epidermis of human digits.

The epidermal-dermal junction of the volar skin of human digits was examined by scanning electron microscopy (SEM). Fixed specimens obtained from cadavers were treated with 6 N NaOH to exfoliate the epithelium. The three-dimensional features of the basal surfaces were clearly visualized by SEM. Epithelial prolongations (intermediate and limiting ridges) protruded towards the dermis, and transverse ridges were visible between them. Nerve fibers and Schwann cells were aggregated around the sweat ducts on the intermediate ridges. Discoid structures were visible among the nerve fibers and Schwann cells. Examination by transmission electron microscopy of ultrathin sections of re-embedded specimens confirmed that the discoid structures were nerve endings that covered the Merkel cells. Minute projections were studded on the basal surfaces of basal keratinocytes. The projections in the intermediate ridges appeared to be villous, whereas the profiles of those in the limiting ridges resembled cobblestones. This morphological difference might be a reflection of function.

Aged↗
PubMed1996

Chronologic analysis of eosinophil granule protein deposition and cell adhesion molecule expression in mite allergen-induced dermatitis in atopic subjects.

To investigate the process of eosinophil recruitment in atopic dermatitis (AD), patch testing with crude dust-mite allergens was performed on normal-appearing skin of 9 adult AD patients with high levels of mite-specific IgE antibodies. Positive reactions were observed in 6 AD subjects, whereas 0 of 7 control subjects showed positive reactions to mite allergens. Positive reaction sites were biopsied chronologically and studied histologically and immunohistochemically. Eosinophils were seen in postcapillary venules in the dermis at 2 h, followed by infiltration of eosinophils at 6 h which peaked at 24 and 48 h. In the epidermis, eosinophilic spongiosis was seen at 48 h. Positive reactions against eosinophil granule proteins were observed in connective tissues as well as on eosinophils. Almost all infiltrating eosinophils were positive for BMK-13 (an antibody against major basic protein); half of them were positive for EG2 (an antibody against eosinophil cationic protein). With regard to adhesion molecules, expression of E-selectin and intercellular adhesion molecule-1 endothelial cells was up-regulated as infiltrating eosinophils increased in number. These findings suggest that eosinophil transmigration from endothelial cells and eosinophil degranulation play important roles in initiating early AD lesions induced by transepidermal mite allergen permeation.

Adult↗
PubMed1996

Effect of alcohol on tumor growth of hepatocellular carcinoma with type C cirrhosis.

To investigate the influence of alcohol intake on tumor growth of hepatocellular carcinoma (HCC) in patients with type C cirrhosis, we examined the tumor volume doubling time (TVDT) of 35 nodules from 35 cases of HCC, calculated through ultrasonographic imaging. The patients were divided into two groups according to their drinking habit; 21 habitual drinkers (alcohol group; 80g ethanol/day for 5 years), and 14 patients without alcohol abuse (non alcoholic group). The average value of TVDT in the alcoholic group was 78 +/- 47 days, although that of the non alcoholic group was 142 +/- 60 days. A statistically significant difference (p < 0.01) was found between the two groups. Of the 21 habitual alcohol drinkers, 8 refrained from drinking after detection of HCC; their TVDT was about 30 days shorter than those who continued alcohol intake. In conclusion we found that alcohol intake was closely related to the tumor growth of HCC in patients with type C cirrhosis.

Adult↗
PubMed1996

Transgenic mouse and gene therapy.

In the transgenic mouse, a specific gene can be transduced or deleted to study its function and relation to human diseases. Recently, various lines of transgenic mice that overexpress or lack a specific gene have been established and are available to study the pathophysiology of human diseases, including atherosclerosis, diabetes, and hyperlipidemia. We have established transgenic mouse lines with an integrated rat apolipoprotein (apo) E gene under control of the metallothionein promoter. Overexpression of apoE in the liver reduced plasma cholesterol and triglyceride levels and prevented diet-induced hypercholesterolemia. Another transgenic model with overexpression of apoE under control of the H2 Ld promoter in the arterial wall was established. In this model, the formation of fatty streak lesions was markedly inhibited, suggesting that apoE has antiatherogenic actions. Finally, we discuss gene therapy, which will be an important therapeutic approach to correct genetic abnormalities found in metabolic diseases.

Animals↗
PubMed1996

Enhanced expression of platelet-derived growth factor-beta receptor by high glucose. Involvement of platelet-derived growth factor in diabetic angiopathy.

Coronary heart disease is a major complication of diabetic subjects, and platelet-derived growth factor (PDGF) has been implicated in the development of atherosclerosis. We investigated the effects of high glucose on expression of PDGF-beta receptor. In a binding assay with 125I-labeled PDGF-BB homodimer, high concentrations of glucose increased high-affinity binding of PDGF-BB on human monocyte-derived macrophages and rabbit aortic medial smooth muscle cells. Northern blot analysis confirmed the enhanced effect of glucose on expression of PDGF-beta receptor mRNA in human monocyte-derived macrophages. The protein kinase C inhibitor, staurosporin, completely suppressed an increase in PDGF-BB binding by high glucose, and high glucose significantly activated protein kinase C. These results indicated that PDGF-beta receptor expression was enhanced by high glucose through the activation of protein kinase C. Furthermore, we observed similar effects of high glucose on both PDGF-beta receptor expression and protein kinase C activation in rat mesangial cells and human capillary endothelial cells. Our results suggest that stimulation of the PDGF system is significantly involved in the development not only of diabetic atherosclerosis but also of microangiopathy.

Alkaloids↗
PubMed1996

Dose-dependent effect of niceritrol on plasma lipoprotein-a.

Lipoprotein-a, Lp(a), is a variant form of low density lipoprotein (LDL) that contains apolipoprotein-a, whose structure has 75-85% homology with plasminogen. Elevated plasma levels of Lp(a) are considered to be one of the independent risk factors for cardiovascular disease. We studied the effects of niceritrol, a nicotinic acid derivative, on plasma Lp(a) levels in 72 patients with hypercholesterolaemia. The dose of niceritrol was increased every 4 weeks, from 750 to 1500 and then to 2250 mg day-1. The final dose was adjusted to obtain a plasma cholesterol level less than 5.69 mmol l-1. Niceritrol led to significant decreases in plasma levels of median Lp(a), from 16.1 mg dl-1 (interquartile intervals, 8.7 to 32.8) to 11.1 mg dl-1 (interquartile intervals, 6.6 to 21), the mean reduction rate being 17.6%. In the group with pretreatment Lp(a) levels of over 20 mg dl-1, Lp(a) decreased by 10.0, 22.0 and 31.8% at the doses of 750, 1500, and 2250 mg day-1, respectively. In the group with levels less than 20 mg dl-1, only the dose of 2250 mg day-1 was effective in the reduction of Lp(a). The results suggest that the reduction of Lp(a) was dependent on the dose of niceritrol and on the pretreatment level of Lp(a). In conclusion, niceritrol is effective, in a dose-dependent manner, for reducing Lp(a) levels.

Aged↗
PubMed1996

Role of macrophages in pulmonary late-phase reaction in guinea pigs.

To examine the role of macrophages in pulmonary late-phase reaction (LPR), macrophages were reduced in sensitized guinea pigs by an intravenous injection of liposome-encapsulated dichloromethylene diphosphonate (Cl2MDP). Macrophage reduction was evaluated by bronchoalveolar lavage (BAL) fluid analysis. In Cl2MDP liposome-treated animals, the number of macrophages in BAL fluid significantly decreased by 56% compared with PBS liposome-treated animals (1.6 +/- 0.1 vs. 3.6 +/- 0.4 x 10(6) cells, p < 0.01). The number of neutrophils, eosinophils, or lymphocytes in BAL fluid showed no significant changes in these two groups. Both PBS and Cl2MDP liposome-treated sensitized guinea pigs were challenged with an inhalation of antigen, and respiratory resistance (Rrs) was measured. PBS liposome-treated animals (control) exhibited both immediate (IPR) and late (LPR) increases in Rrs. The maximal increases in Rrs at IPR and LPR were 217 +/- 19 and 187 +/- 20% of baseline values, respectively (n = 9). On the other hand, Cl2MDP liposome-treated animals showed an immediate increase in Rrs (IPR); however, the late increase in Rrs (LPR) was significantly suppressed (p < 0.05). The maximal increases in Rrs at IPR and LPR were 200 +/- 13 and 134 +/- 11% of baseline values, respectively (n = 8). In Cl2MDP liposome-treated animals, the numbers of macrophages and neutrophils in BAL fluid 4 hr after antigen challenge decreased by 45% and 54%, respectively, compared with PBS liposome-treated animals (p < 0.05). In Cl2MDP liposome-treated animals, neutrophil chemotactic activity in BAL fluid 4 hr after antigen challenge decreased by 59% compared with PBS liposome-treated animals (p < 0.05). These results suggest that macrophages play an important role in the development of pulmonary LPR through the induction of neutrophil accumulation in the airways.

Animals↗
PubMed1996

Effects of dietary n-3/n-6 and polyunsaturated fatty acid/saturated fatty acid ratios on platelet aggregation and lipid metabolism in rats.

We studied the effects of dietary lipids on platelet aggregation and lipid metabolism in rats by varying the n-3/n-6 ration while maintaining the polyunsaturated fatty acid/saturated fatty acid (P/S) ratio fixed, and vice versa. After two weeks, the platelet counts decreased as the dietary n-3/n-6 ratio rose, and platelet aggregation was sufficiently suppressed at the ratio of 0.2. Differences in the dietary P/S ratio, however, did not affect either the platelet counts nor platelet aggregation. As the dietary n-3/n-6 ratio rose, the proportion of arachidonic acid (AA) in the plasma and the phospholipids (PL) of the platelets and aorta decreased gradually, whereas the proportion of eicosapentaenoic acid (EPA) in each tissue increased gradually. The proportion of EPA was higher in the platelets than in the aorta, while that of docosahexaenoic acid (DHA) was higher in the latter. The production of platelet thromboxane A2 (TXA2) and aortic prostacyclin (PGI2) showed sharp declines, from the values for the n-3/n-6 ratio of 0.02 (control) to those for 0.5. These results suggest that the n-3/n-6 ratio of dietary fats necessary to ensure the suppression of platelet aggregation in normal rats would be at least 0.2 and no more than 0.5.

Animals↗
PubMed1996

Effects of different types of dietary fiber preparations isolated from bamboo shoots, edible burdock, apple and corn on fecal steroid profiles of rats.

This study was conducted to evaluate the effects of different types of dietary fibers (DF) under the conditions with or without cholesterol (Chol) loading on the amount and composition of steroids in rat feces. Rats were fed Chol-unsupplied diets containing 10% lard and 5% DF preparation isolated from four kinds of food, bamboo shoots, edible burdock, apple and corn, for three weeks. The respective diets were supplemented with 0.5% Chol and then given to the rats for a further two weeks. The excretion of total bile acid (BA) and several major BAs increased significantly in the apple group with or without Chol loading when compared with that in the cellulose (CP) or other DF groups. The tendency in the apple group was more noticeable when the diet was supplemented with Chol. This is presumably a major reason for the tendency of decrease in serum and liver Chol concentrations in the apple group. The ratio of secondary BAs to total BA in the feces was significantly low in the apple group. Although the lithocholic acid (LCA)/deoxycholic acid (DCA) ratio, a risk index for colorectal cancer, was significantly lower in the bamboo, burdock and apple groups than in the CP or corn groups when given the diet without Chol, the differences disappeared with the addition of Chol. The proportion of coprostanol, a secondary metabolite of Chol, was smaller in the former three groups than in the CP or corn groups. These results suggest that the intake of some DF by host animals works beneficially for the microbial conversion of BA and Chol in the large intestine but that the addition of Chol acts to cancel such beneficial effects.

Animal Feed↗
PubMed1996

An evaluation of hepatic ultrasound speed in injury models in rats: correlation with tissue constituents.

The speed of sound through the livers of 32 male Sprague-Dawley rats was measured. The study population consisted of four experimental groups: control, acute liver injury induced by carbon tetrachloride, fatty liver induced by a choline-deficient diet, and liver cirrhosis induced by administration of N-diethylnitrosamine. To examine possible correlations between the speed of sound and liver histology, biochemical measurements of the water, fat, and collagen content were made. The aim of the present study was to determine the effects of the characteristics of diseased liver tissue on the speed of sound, by studying the tissue constituents biochemically and by using a more accurate measurement of the speed of sound. The sound speed was 1591.6 +/- 6.7 m/s in the acute liver injury group, 1531.4 +/- 18.4 m/s in the fatty liver group, and 1624.9 +/- 6.7 m/s in the liver cirrhosis group. No significant correlation existed between the speed of sound and the water content in all groups taken together, whereas a good correlation was found in the fatty liver group (P < 0.0001, r = -0.858) and in cirrhosis (P < 0.0001, r = 0.760) when the groups were examined separately. These results indicate that the speed of sound is useful for diagnosing fatty liver for predicting the fat content.

Animals↗
PubMed1996

Mucopolysaccharidosis IVA: four new exonic mutations in patients with N-acetylgalactosamine-6-sulfate sulfatase deficiency.

We report four new mutations in Japanese patients with mucopolysaccharidosis IVA (MPSIVA) who were heterozygous for a common double gene deletion. A nonsense mutation of CAG to TAG at codon 148 in exon 4 was identified, resulting in a change of Q to a stop codon and three missense mutations. V (GTC) to A (GCC) at codon 138 in exon 4, P (CCC) to S (TCC) at codon 151 in exon 5, and P (CCC) to L (CTC) at codon 151 in exon 5. Introduction of these mutations into the normal GALNS cDNA and transient expression in cultured fibroblasts resulted in a significant decrease in the enzyme activity. V138A and Q148X mutations result in changes of restriction site, which were analyzed by restriction-enzyme assay. P151S and P151L mutations that did not alter the restriction site were detected by direct sequencing or allele specific oligohybridization. Detection of the double gene deletion was initially done using Southern blots and was confirmed by PCR. Haplotypes were determined using seven polymorphisms to the GALNS locus in families with the double gene deletion. Haplotype analysis showed that the common double gene deletion occurred on a single haplotype, except for some variation in a VNTR-like polymorphism. This finding is consistent with a common founder for all individuals with this mutation.

Adolescent↗
PubMed1996

[A case of predominant right thalamic infarction with severe verbal memory disturbance].

We encountered a 45-year-old right-handed man who had suffered a predominant right thalamic infarction and complained of memory loss. Performance on the Miyake Test (recall of ten pairs of related and unrelated words), the Rey Osterrieth Complex Figures, the Benton Test of Visual Retention and the Wechsler Memory Scale-R disclosed a severe verbal memory disturbance associated with a little, if any, visual memory disturbance. An MRI study revealed bilateral lesions limited to the thalamus involving most of the right anterior nucleus (AN), mediodorsal nucleus (MD), ventrolateral nucleus (VL), and centromedial nucleus (CM), as well as a small part of the left MD, and CM. HM-PAO-SPECT scans showed areas of decreased cerebral blood flow not only in the right thalamus but in the medial and basilar region of the right temporal lobe. It is noteworthy that our patient had a predominant right thalamic lesion and exhibited a severe verbal memory disturbance rather than visual memory disturbance. This suggests that the right hemisphere is dominant for verbal memory function in this patient.

Cerebral Infarction↗
PubMed1996

[Diagnosis of superficial-type early carcinoma of the gallbladder by endoscopic ultrasonography--comparison with ultrasonography].

The detectability of superficial-type carcinoma of the gallbladder by ultrasonography (US) and endoscopic ultrasonography (EUS) were investigated. Eight patients with such carcinoma of the gallbladder were reviewed. They had undergone both US and EUS previous to surgery. The tumor was detected in 3 patients by US, 2 patients with IIa + IIb-type carcinoma and 1 patient with IIa-type carcinoma. Those lesions were visualized as localized thickening of the gallbladder wall or as broad-based tumor. In 2 patients, lesions were not initially detected by US, but were shown by US after the examination by EUS. The tumor was detected by EUS also in 1 case of IIb + IIa-type carcinoma besides those 3 patients mentioned above. All four of these lesions were visualized as broad-based tumor by EUS. It was difficult to detect pure IIb-type or small IIa-type carcinoma even by EUS. In patients with concomitant acute cholecystitis or gallbladder stone, it was difficult to evaluate the abnormal findings of the gallbladder wall.

Aged↗
PubMed1996

[Significance of 123I-metaiodobenzylguanidine SPECT for detecting left ventricular involvement in patients with arrhythmogenic right ventricular dysplasia].

The right ventricle being primarily involved in ARVD, recent reports indicate the presence of histological and functional abnormalities in the left ventricle for some patients with ARVD. The aim of this study was to evaluate the significance of myocardial sympathetic dysfunction as an early sign of left ventricular (LV) involvement by 123I-MIBG (MIBG) SPECT and to compare the findings with those of 201TlCl (Tl) SPECT, radionuclide left ventriculography, ultrafast computed tomography (UFCT), magnetic resonance imaging (MRI) and echo-cardiography in 10 patients (pts) with ARVD. MIBG defects in LV regions were detected in 9 pts. Seven of the 9 pts showed MIBG defects in LV regions adjacent to RV. The subjects were divided into 2 groups based on left ventriculography, 5 with normal LVEF (> 55%) and 5 with reduced LVEF. In the normal LVEF group, 4 pts showed MIBG defects and 2 pts showed TI defects, and MIBG defects were larger than TI defects (ES: 14 +/- 6 vs. 5 +/- 7, p <0.05). In reduced LVEF group, all of 5 pts showed MIBG and TI defects, and MIBG defects were larger than TI defects (ES: 42 +/- 12 vs. 25 +/- 3, p <0.05). In comparison with normal LVEF group, reduced LVEF group showed larger and more severe MIBG defects (ES: 42 +/- 12 vs. 14 +/- 6, p <0.01, SS: 44 +/- 31 vs. 8 +/- 7, p <0.05). UFCT and MRI showed abnormal findings indicating LV fatty infiltration in only 3 of reduced LVEF group. Thus, MIBG showed abnormal distributions in the left ventricle with the highest frequency in all these modalities. These results suggest that MIBG SPECT provides a sensitive marker for detecting LV involvement in ARVD. Also, the extent of MIBG distribution abnormalities is helpful in assessing the severity of left ventricular involvement in patients with ARVD.

3-Iodobenzylguanidine↗
PubMed1996

Pharmacologic modulation of delayed-type hypersensitivity in mice.

In order to determine the mast cell requirements in murine delayed-type hypersensitivity (DTH), the effects of the antihistamine chlorpheniramine, the inhibitor of mast cell degranulation repirinast (CAS 73080-51-0, MY-5116), the lipoxygenase and cyclooxygenase inhibitor BW-755C (3-amino-1-[m-(trifluoromethyl)phenyl]-2-pyrazoline), and the cyclooxygenase inhibitors ibuprofen, diclofenac and phenylbutazone on murine DTH reactions were examined. When chlorpheniramine (50 mg/kg) was administered orally immediately after, 5 h, or 9 h after antigen challenge, it did not show any effect on sheep red blood cells (SRBC)-induced delayed footpad reaction (FPR) in mice. On the other hand, when chlorpheniramine was administered orally 16 h after antigen challenge, it significantly inhibited SRBC-induced delayed FPR (p < 0.01). When repirinast (30, 100 mg/ kg) was administered orally 16 h after antigen challenge, it significantly inhibited delayed FPR in a dose-dependent manner. BW-755C (50 mg/kg) showed no significant effect on delayed FPR when it was administered 1 h, 7 h, or 13 h after challenge. However, it significantly inhibited delayed FPR when it was administered 16 h after antigen challenge (p < 0.01). Ibuprofen, diclofenac, or phenylbutazone showed no significant effect on delayed FPR even if it was administered 16 h after antigen challenge. These results demonstrate that mast cells could be involved in DTH reactions and that histamine and leukotrienes may play an important role in DTH reactions in mice.

Animals↗