Biomedical subjects

M Nishida

Publications and source records attributed to M Nishida.

At least 217 records · Page 12Linked to original sources

PubMed1997

Vascular angiotensin-converting enzyme activity in cholesterol-fed rabbits: effects of enalapril.

Many reports have shown inhibitory effects of angiotensin-converting enzyme (ACE) inhibitors on the progression of atherosclerotic plaque lesions in vascular tissue of experimental models. However, no report has shown alterations of ACE activity in vascular tissue during the process of atherosclerosis. We measured ACE activity in plasma and aortic tissue in rabbits fed a cholesterol-rich (1%) or normal diet for 10 weeks. We also evaluated the blood pressure response to angiotensin (Ang) I and II. These data were compared in untreated rabbits and in rabbits receiving chronic treatment with an ACE inhibitor, enalapril (3 mg/kg/day for 10 weeks). ACE activity in aortic tissue, but not in plasma, in cholesterol-fed rabbits was gradually but significantly increased compared with that in noncholesterol-fed rabbits even after the 4-week feeding period, when no atherosclerotic lesion was observed in the aortic tissue. Treatment with enalapril for 10 weeks, but not 4 weeks, significantly reduced the ACE activity in aortic tissue in association with the reductions in the elevated Ang II level and the atherosclerotic plaque area of the aortic tissue. These results indicated that ACE activity in aortic tissue was increased during the early phase of atherosclerotic process.

Angiotensin I↗

PubMed1997

Early morphologic changes of atherosclerosis induced by ventromedial hypothalamic lesion in the spontaneously diabetic Goto-Kakizaki rat.

It is generally thought that typical atherosclerotic lesions do not develop in the rodent. The Goto-Kakizaki (GK) rat is a nonobese strain in which a spontaneous type of non-insulin-dependent diabetes mellitus develops without apparent macroangiopathy. In our previous study, making ventromedial hypothalamic (VMH) lesions in GK rats induced hyperphagia and a further deterioration in glucose metabolism. In the current study, male GK rats in which VMH lesions were made were examined for vascular changes, with special reference to atherosclerotic lesions. Marked hyperglycemia in GK rats with VMH lesions (hereafter referred to as VMH lesion rats) was revealed over an observation period (plasma glucose levels 16 weeks after the operation: VMH lesion GK rats, 19.3 +/- 2.0 mmol/L, vs sham-operated GK rats, 10.1 +/- 1.3 mmol/L; p < 0.0001). Light microscopic observation of the descending aorta in VMH lesion GK rats 16 weeks after the surgery revealed that the intimal thickening and the number of infiltrating cells into the intima were significantly increased as compared with sham-operated GK rats (17531 +/- 3747 microm2 vs 3072 +/- 1192 microm2, p < 0.0001; 15.6 +/- 3.1 per one transverse section vs 6.8 +/- 2.5 per one transverse section, p < 0.0005). Electron microscopic observations demonstrated an increased number of microvilli and lysosomes in endothelial cells, infiltration of macrophages and lymphocytes into the intima, and migration of medial smooth muscle cells into the intima that are considered to be early events in atherosclerosis. These morphologic changes could be induced by a deterioration in glucose metabolism. This rat may thus be useful for studying the process of the initiation of atherosclerosis in diabetes mellitus.

Animals↗

PubMed1997

Early increase of gut intraepithelial mast cell precursors following Strongyloides venezuelensis infection in mice.

The time-course of differentiation/proliferation of mast cells in gut epithelium was investigated in mice infected with the nematode Strongyloides venezuelensis. After infection, expression of proliferating cell nuclear antigen increased in gut intraepithelial mast cells on days 7 to 11, followed by an increase in the number of intraepithelial mast cells from days 11 to 14. Mast cell precursors were defined as cells that formed mast cell colonies in methylcellulose culture. After infection, the numbers of mast cell precursors in the population of gut intraepithelial mononuclear cells (IEMNC) increased significantly on day 3 and returned to the pre-infection level by day 7. Mast cell precursors in Peyer's patches, mesenteric lymph nodes (MLN), and spleen also increased from day 7 p.i. Production of IL-3 and IL-4 in MLN and spleen were increased between 7 and 11 days p.i. These results show that murine intestinal mastocytosis is initiated by an early increase in mast cell precursor number in the gut epithelium followed by proliferation/differentiation of mast cells. Mast cell precursor numbers increased even before the production of IL-3 and IL-4 in MLN and spleen, suggesting that some local factors might be involved in this phenomenon.

Animals↗

PubMed1997

Importance of intra-abdominal visceral fat accumulation to coronary atherosclerosis in heterozygous familial hypercholesterolaemia.

OBJECTIVES: Hyper-low-density lipoprotein (LDL)-cholesterolaemia is a potent risk factor for coronary atherosclerosis. We have recently demonstrated that a cluster of risk factors including insulin resistance, glucose intolerance, hypertriglyceridaemia, and hypertension based on intra-abdominal visceral fat accumulation are closely related to coronary artery disease. In the current study, we evaluated the relationship between visceral fat accumulation and the severity and distribution of coronary atherosclerosis in familial hypercholesterolaemia (FH). DESIGN: The effect of visceral fat accumulation on coronary lesions and risk factors in patients with FH was investigated. SUBJECTS: Thirty-one male patients with heterozygous FH who underwent coronary angiography. MEASUREMENTS: Abdominal fat distribution was estimated by a cross-sectional computed tomographic scan at the umbilical level. Plasma lipid, glucose and insulin concentrations and blood pressure were measured. A 75 g oral glucose tolerance test was also performed. RESULTS: The patients were divided into two groups according to the degree of visceral fat accumulation. Fifteen patients had high visceral fat accumulation (High VF group) and 16 patients had normal visceral fat accumulation (Normal VF group). Body mass index (BMI) and subcutaneous fat area were significantly higher in the high VF group. Baseline serum triglyceride was significantly higher and baseline low-density lipoprotein (LDL)-cholesterol and reduction of LDL-cholesterol during treatment were significantly lower in High VF group. Fasting plasma glucose and insulin concentrations, and systolic and diastolic pressures were significantly higher in the High VF group. Significant correlations were found between visceral fat area and the sum of the glucose and insulin concentration during an oral glucose tolerance test. Visceral fat area was significantly correlated with the severity of coronary stenosis index. Distal coronary lesions were significantly more frequent in the High VF group. Moreover, the correlation between the visceral fat area and coronary stenosis index was found to be independent of age, BMI, and subcutaneous fat area by multiple regression analysis. CONCLUSIONS: Visceral fat accumulation is a potent cardiovascular risk factor in heterozygous FH.

Abdomen↗

PubMed1997

Two decades of annual medical examinations in Japanese obese children: do obese children grow into obese adults?

OBJECTIVE: To investigate trends in frequency of obese children in Japan over two decades, the frequency of obese children who grow into obese adults and predictive factors for adult obesity. DESIGN: Annual cross-sectional studies for 22 y (1974-1995) with a follow-up study. SUBJECTS: Cross-sectional: Cumulatively 13,186 obese (% of standard body weight (SBW): > or = 120%) schoolchildren including 3158 extremely obese (> or = 140% of SBW) children out of 203,088 schoolchildren (age: 6-14 y) in Izumiohtsu City, Osaka, Japan. FOLLOW-UP: 151 initially obese children (initial age: 6-14 y and age at follow-up: 20-35 y) who lived in Izumiohtsu City. CONTROL: 3552 Japanese men and 4631 Japanese women (age: 20-35 y). MEASUREMENTS: Cross-sectional: height, weight, trunk circumference, skin-fold thickness, blood pressure and blood biochemicals. FOLLOW-UP: height, weight, trunk circumference, skin-fold thickness during childhood, and body height and weight at follow-up. Adulthood obesity: > or = 120% of the average body mass indices (BMI) of the controls. RESULTS: Frequency of obese children increased from 5% to more than 10%, and that of extremely obese children increased from 1% to more than 2% during these 22 y. These increases were most prominent in the schoolboys aged 9-11 y. Prevalence of hyperglycemia and hyperlipidemia in the extremely obese children did not change, and that of hypertension and abnormal liver function gradually decreased during these two decades. After coming of age, 32.2% of the initially obese boys (relative risk: 5.3) and 41.0% of the initially obese girls (relative risk: 6.7) remained obese. BMI, percentage of the SBW and skin-fold thickness at the biceps during childhood were significantly larger in currently-obese girls. Positive correlations were demonstrated between these variables and percentage SBW at follow-up. CONCLUSIONS: Childhood obesity is increasing in Japan, especially in boys aged 9-11 y. Approximately 32% of the obese boys and 41% of the obese girls grow into obese adults, and the degree of obesity is a predictive factor for adult obesity.

Adolescent↗

PubMed1997

Visceral fat accumulation as an important risk factor for obstructive sleep apnoea syndrome in obese subjects.

OBJECTIVES: It is well known that obstructive sleep apnoea-(OSA) is frequently associated with obesity. In the current study, we investigated the correlation between abdominal visceral fat accumulation and the presence of OSA in obese subjects. SUBJECTS: A consecutive series of 37 patients (17 men and 20 women) with primary obesity who were admitted to the Second Department of Internal Medicine. Osaka University Hospital, were investigated Patients with OSA were designated as those whose apnoea index (number of apnoea h-1 of sleep) was more than 5. MAIN OUTCOME MEASURES: The distribution of body fat was determined using computed tomographic sections. The upper airway dimensions were evaluated with indices obtained by cephalometry in both inspiratory and expiratory phases. RESULTS: Visceral adipose tissue (AT) area which was measured at the level of the umbilicus, and its ratio to total AT area were both significantly greater in OSA patients as compared with those in non-OSA patients. All subjects whose visceral AT area measured more than 220 cm2 manifested OSA. These two parameters also closely correlated with an increase in apnoea index. A multiple linear regression analysis revealed that the visceral AT area significantly correlated to apnoea index when age, AT mass and lean body mass were taken into account. The fluctuations of the upper airway were significantly greater in the large visceral fat group than in the small visceral fat group. CONCLUSIONS: These results suggest that visceral fat accumulation is an important risk indicator for OSA in obese subjects.

Adipose Tissue↗

PubMed1997

Nematode infection induces Th2 cell-associated immune responses in LEC mutant rats with helper T cell immunodeficiency.

Long-Evans Cinnamon (LEC) rats have maturational arrest of CD4+8- T cells from CD4+8+ cells in the thymus. Despite this, CD4+8- T cells are always present in peripheral lymphoid organs of LEC rats, suggesting that these CD4+8- T cells are generated by an uncommon pathway. We investigated the role of LEC rat peripheral CD4+8- T cells in Th2-associated responses to infection with the nematode Nippostrongylus brasiliensis. After infection, the numbers of CD4+8- TCR alpha beta + T cells significantly increased in mesenteric lymph nodes (MLN) and the spleen, while those in the thymus were still negligible. Infection also induced significant up-regulation of IL-4 gene expression in LEC rat MLN cells. Total serum IgE levels in LEC rats were markedly increased two weeks after infection. Mucosal mast cell responses in the gut and lungs of LEC rats were induced as prominently as in control Long-Evans Agouti (LEA) rats. Faecal egg count data indicated that LEC rats rejected nematodes faster than LEA rats. These results suggested that Th2-associated responses can be induced by nematode infection in LEC rats probably through the extrathymic recruitment and proliferation of CD4+8- TCR alpha beta + T cells.

Animals↗

PubMed1997

The presence of a manganese-rich particle in lysosome of rat pancreas due to excess manganese treatment.

Manganese (Mn) accumulates at a higher level in the pancreas than in any other organs when excess Mn is administered to the rat. The present study is carried out to analyze the intracellular localization of Mn existed in the pancreatic cell of Mn-treated rats. Transmission electron microscope and X-ray micro-analysis connected with a rapid freezing fixation technique showed that a large amount of Mn was localized in lysosomal particles of the pancreatic cell of Mn-treated rats. The Mn-rich particles disappeared when the element-administration was discontinued, showing that the accumulation of Mn is reversible. To confirm that Mn is in the lysosomes, a centrifugal subcellular-fractionation and a neutron activation analysis were carried out. The result indicated that much Mn existed in the lysosomal fraction.

Animals↗

PubMed1997

A new semi-solid agar dilution method for determining amoxycillin, clarithromycin and azithromycin MICs for Helicobacter pylori isolates.

The MICs of amoxycillin, clarithromycin and azithromycin for 26 strains of Helicobacter pylori were determined using Mueller-Hinton semi-solid agar (SSA) without CO2 incubation, as in the conventional agar dilution method. The tested H. pylori strains grew satisfactorily in the SSA method within 48 h of incubation. Reasonable values of MICs of three antibiotics for these strains were obtained by this method, avoiding the inactivation of macrolides due to acidification of the medium. By this method, the MICs of the antibiotics for the reference strains were within the acceptable NCCLS ranges for quality control.

Amoxicillin↗

PubMed1997

Large sixth nerve neuroma involving the prepontine region: case report.

OBJECTIVE AND IMPORTANCE: Tumors originating from the cranial nerves are uncommon, except for the acoustic and trigeminal neuromas. The sixth nerve, however, has the potential to generate neuromas with characteristic clinical features. CLINICAL PRESENTATION: A 54-year-old woman presented with diplopia and increased intracranial pressure. Magnetic resonance imaging showed a large mass in the prepontine region. Surgery was performed via a condylar approach and demonstrated a tumor originating from the prepontine portion of the sixth nerve. CONCLUSION: The sixth nerve neuroma at the pontomedullary junction showed characteristic clinical features and could be successfully removed via a condylar approach.

Abducens Nerve↗

PubMed1997

New mechanism to reduce the size of the monopivot magnetic suspension blood pump: direct drive mechanism.

Size reduction of the monopivot magnetic suspension blood pump has been achieved by reducing the size of the magnetic suspension and employing a direct drive mechanism in place of a brushless DC motor and a magnetic coupling. The flow has also been improved using a closed hollow impeller to remove flow obstruction at the inlet and using radial straight vanes to reduce the impeller speed by 30%. Hemolysis testing was conducted for the new models. Results showed that model DD1 presented only a slightly higher level of hemolysis than a regular extracorporeal centrifugal pump.

Centrifugation↗

PubMed1997

Quantitative visualization of flow through a centrifugal blood pump: effect of washout holes.

To clarify the effect of washout holes on the flow in a centrifugal blood pump to prevent blood stagnation, a quantitative flow visualization technique was applied to compare flows in models with and without washout holes. A scaled-up model of a prototype pump and a high speed video camera were used for the flow visualization, and images were processed by particle tracking velocimetry. Particular attention was paid to the flow through the gaps behind and in front of the impeller. The results showed that in the gap behind the impeller, washout holes caused not only an inward flow, but also an increase in the tangential velocities. In the gap in front of the impeller, washout holes caused an outward flow and a decrease in the tangential velocities. Head flow characteristics were little affected by the washout holes in this initial design for which the flow through the washout holes was set to be approximately 10% of the flow in the external circuit. These results suggest that the flow through washout holes is significant in the prevention of blood stagnation in 2 ways. First, the inward radial velocity behind the impeller and outward velocity in front of the impeller result in fluid exchange, and second, a tangential velocity increase reduces fluid stagnation behind the impeller.

Blood Flow Velocity↗

PubMed1997

Immunohistochemical distribution of lymph capillaries and blood capillaries in the synovial membrane in cases of internal derangement of the temporomandibular joint.

The distribution of lymph capillaries and blood capillaries in the synovial membrane was examined immunohistologically with anti-human collagen IV antibody and anti-human von Willebrand factor in 26 human temporomandibular joint (TMJ) samples comprising discs with adjoining synovial membrane from 10 control TMJs and from 16 TMJs with internal derangement. Three different distribution types were observed in the synovial membrane. In the control samples, the occurrence of blood capillaries and lymph capillaries was rare. In mildly hyperplastic synovitis, lymph capillaries were observed just beneath the surface of the synovial membrane, whereas blood capillaries occurred in a little deeper layer of the synovial membrane. In a severely hyperplastic synovitis, both lymph and blood capillaries were observed frequently. The present results suggest that the different distribution patterns of lymph capillaries and blood capillaries reflect the degree of synovitis but can not be attributed to specific clinical symptoms.

Adult↗

PubMed1997

Gas dispersion in a model pulmonary bifurcation during oscillatory flow.

In order to clarify the gas transport process in high-frequency oscillation, we measured the axial velocity profile and the axial effective diffusivity in a single asymmetric bifurcating tube, based on the Horsfield airway model, with sinusoidally oscillatory flow. The axial velocity profiles were measured using a laser-Doppler velocimeter, and the effective diffusivities were evaluated using a simple bolus injection method. The axial velocity profile was found to be nonuniform, promoting axial gas dispersion by the spread of the concentration profile and lateral mixing. The geometric asymmetry of the bifurcation was responsible for the difference in gas transport between the main bronchi. The axial gas transport in the left main bronchus was 2.3 times as large as that of the straight tube, whereas the gas transport in the right main bronchus was slightly larger than that of the straight tube. Thus localized variation in gas transport characterized the heterogeneous respiratory function of the lung.

Bronchi↗

PubMed1997

[Urease-negative Helicobacter pylori isolates from gastrointestinal mucosa of patients with peptic ulcer].

It is well known that Helicobacter pylori produced a large amount of urease which plays an important role in the maintenance of infection and adhesion. Two thousand three hundred and thirty-one specimens of the gastrointestinal mucosa were obtained from patients with peptic ulcer to isolate H. pylori strains. Of these specimens, 1602 strains of H. pylori were isolated and 7 urease-negative H. pylori strains were found. Biological characteristics (except urease production) of urease-negative H. pylori were in accord with urease-positive reference strains (ATCC strains). Furthermore, these urease-negative strains were confirmed to be H. pylori strains by PCR. These results suggest that the emergence of urease-negative strains pose a new problem for H. pylori infection in patients with peptic ulcer.

Gastric Mucosa↗

PubMed1997

[Gentamicin-induced alteration in drug susceptibility and lipopolysaccharide-composition of Pseudomonas aeruginosa isolates].

Emergency of multi-drug resistance in Pseudomonas aeruginosa isolates after exposure to gentamicin was investigated with reference to their LPS-compositions. Three strains each of P. aeruginosa, different in LPS-compositions (long- and short-LPS strains, and LPS-deficient strain) were once or repeatedly incubated overnight at 35 degrees C in Mueller-Hinton broth including different concentrations of gentamicin, a poly-cationic antibiotic. LPS-compositions of the bacteria which survived and were grown after exposure to gentamicin were analyzed and the susceptibility to some of anti-pseudomonal drugs was determined. Of the test 9 strains after single exposure, No. 4 (long-LPS) and No. 41 (short-LPS) formed the LPS-deficient mutants. The resistance to ceftazidime and gentamicin was found in No. 4 strain, but not in No. 41 strain. Drug resistance in different patterns was also found in Nos. 43, 29, 45 and 52 strains without any change in their LPS-compositions. Contrary to these results, the susceptibility to norflxacin increased in Nos. 21 and 45 strains without any change in their LPS-compositions. After repeated exposures to gentamicin, the LPS-compositions of Nos. 4 and 14 (short-LPS) were altered and formed the LPS-deficient and the Intermediate-LPS (between short and long compositions) mutants, respectively. The LPS-alteration in both strains were accompanied by the development of resistance to ceftazidime and gentamicin, respectively. The drug resistance in different patterns were also found in Nos. 43, 156, 29, 41, 21, 45 and 52 strains, without any change in the LPS-compositions, whereas the increase in susceptibility to norfloxacin was simultaneously found in No. 45 strain. The ionic-binding of [3H]-gentamicin to the cell surfaces of two LPS-deficient mutants of P. aeruginosa decreased markedly, in comparison with that of the respective parents, and these results might lead to the drug resistance in the LPS-deficient mutants. However, the gentamicin-induced resistance of some strains of P. aeruginosa (but no change in the LPS-compositions) to the test drugs including gentamicin indicates a possibility that negative charges on the bacterial surface were decreased by the drug exposure. The drug resistance and LPS-compositions in the gentamicin-induced mutants of P. aeruginosa were stable during or after the 15th in vitro serial transfers.

Anti-Bacterial Agents↗

PubMed1997

[Study of diarrhea-inducing strains of Escherichia coli mainly isolated in Kanto area between June and September 1996].

A total of 21,609 faecal specimens obtained from patients with diarrhea mainly in Kanto area between June and September 1996 were investigated to identify the causative pathogens for diarrhea. One-hundred fifty-seven strains of Escherichia coli of 29 different O-serotypes were isolated as the causative pathogens, which were previously recognized to induce severe abdominal cramps and diarrhea. Of these, 114 strains, in which the possibility of enterohemorrhagic E. coli due to their O-serotypes was predicted, were examined for the producibility of Vero toxins. Twenty-six (76.5%) of the 34 strains of E. coli O157 produced the Vero toxins, and other 8 strains were the non-producers. Twenty of the 26 producers produced both VT1 and VT2, whereas the other 6 strains produced VT2 only. Furthermore, 4 strains of E. coli O26, and 1 strain each of E. coli O125 and O126 produced Vero toxins. Thirty-two of the 114 strains, isolated from the patients with diarrhea and selected as the enterohemorrhagic E. coli according to the specific O-serotypes, were actually confirmed produce Vero toxins. Thirty-four strains of E. coli O157 tested were susceptible to all antibiotics such as ampicillin, doxycylin, levofloxacin, fosfomycin, chloramphenicol and polymyxin B, and no strains resistant to levofloxacin, polymyxin B and fosfomycin were found.

Bacterial Toxins↗

PubMed1997

Using acoustic radiation force as a concentration method for erythrocytes.

We investigated the potential damage inflicted on erythrocytes by acoustic radiation force when the cells are concentrated by a 500-kHz ultrasonic standing wave at the pressure node. The extent of the damage was estimated from the concentrations of potassium ions, iron complexes, and lactate dehydrogenase released from the cells. After 2 min of ultrasound irradiation at 12.8 mJ/m3, the cells concentrated on the pressure node, with a cell distribution half-width of 138 microns; no significant release of intracellular components was detected, even after 15 min of irradiation. The results indicate that even small ions like potassium are not released as a result of ultrasound irradiation on cell membranes without cavitation, and they demonstrate the potential use of acoustic radiation force for concentrating living cells in biomedical applications.

Acoustics↗