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Biomedical subjects

H Kyono

Publications and source records attributed to H Kyono.

At least 19 recordsLinked to original sources
PubMed1999

Acute biological effects of intratracheally instilled titanium dioxide whiskers compared with nonfibrous titanium dioxide and amosite in rats.

The dimensions of man-made mineral fiber whiskers are similar to those of some kinds of asbestos. Thus these mineral fibers raise the concern for potential health hazard for workers exposed in the occupational environments. This study was designed to define acute biological effects of intratracheally administered titanium dioxide whiskers (TO1) compared with nonfibrous titanium dioxide (TOP) and UICC amosite (Ams), and their relations to acute lung inflammation in rats. The observed geometric mean length (microm) and width (microm) and geometric standard deviation are: TO1(2.1[2.0], 0.14[1. 53]); Ams (4.3[3.3], 0.31[1.9]); and TOP (50 nm, 1-2 microm aggregates). Ten-week-old Wistar-Jcl male rats received a single tracheal injection of test materials at doses between 0.05 and 1.0 mg/rat. Control animals were injected with the same volume of saline. Lung tissue and bronchoalveolar lavage (BAL) fluid were collected from rats on days 1, 3, and 7 after administration. In the group injected with TO1, total protein, cytokine-induced neutrophil chemoattractant (CINC)/growth-regulated gene product (GRO), interleukin (IL) 1beta, and tumor necrosis factor (TNF) alpha increased on day 1. Subsequently, total elastolytic activity and fucose levels in BAL increased by day 3. All parameters, except for fucose in BAL, recovered to the normal levels. Animals in the Ams group showed increased total protein and CINC/GRO and decreased total elastolytic activity in a dose-dependent manner on day 1. The fucose level increased on day 3 in the Ams group. All parameters returned to their control levels on day 7. Animals in the TOP group did not show significant changes any of parameters during the experimental period. Gene expression of TNF-alpha and monocyte chemoattractant protein (MCP) 3 in the lung increased dose-dependently in the animals treated with the three materials. The mRNAs for eotaxin and MIP-1alpha were overexpressed in the lung of animals treated with Ams and TO1, while RANTES mRNA was overexpressed dose-dependently in the lung of animals treated with Ams on day 1. Onset of inflammatory response was more rapid in the Ams group than the TO1 group. Recovery of the fucose level in BAL was slower in the TO1 group than in the Ams group, though we observed similar histopathological changes in the lung of animals with TO1 or Ams. We conclude that whisker-induced acute biological effects in the lung may be related to the shape of the whiskers and not to their chemical composition or surface crystal structure, showing biological effects similar to those of UICC amosite.

Administration, Inhalation↗
PubMed1999

Pulmonary clearance and lesions in rats after a single inhalation of ultrafine metallic nickel at dose levels comparable to the threshold limit value.

This study aimed to (1) determine the deposition and clearance rates of ultrafine metallic nickel (Uf-Ni) in rats after a 5 hours single inhalation exposure, and (2) to histopathologically examine the pulmonary lesions induced at dose levels comparable to the Occupational Exposure Limit recommended in Japan (OEL). The exposure concentrations of Uf-Ni for the 3 groups were 0.15 (Low), 1.14 (Medium), and 2.54 (High) mg/m3. Five rats/group were sacrificed at 0 h and 1, 3, 7, 14, and 21 days post exposure. The amount of Ni in the lung accumulated dose-dependently. The half-times for Ni in the lung were estimated as 32 days on average, and were similar to each other regardless of the initial dosage. The histopathologically observed pulmonary lesions induced by a single inhalation of Uf-Ni were, (1) a significant increase in lung weight in the High and Medium groups with time, (2) accumulation of foamy alveolar macrophages (AM), (3) degenerated AM indicating alveolar lipoproteinosis which was aggravated for up to 4 weeks in the High group and (4) acute calcification of the degenerated AM was remarkable. The present results suggest that even a single inhalation of Uf-Ni induces potency of lung lesions at dose levels comparable to the OEL (1 mg/m3 as Ni), or the TWA of ACGIH (1.5 mg/m3 for elemental/metal).

Animals↗
PubMed1999

Hexavalent chromium responsible for lung lesions induced by intratracheal instillation of chromium fumes in rats.

Lung toxicity of chromium fumes (Cr fumes) was examined by a single intratracheal instillation into rats of 10.6 mg and 21.3 mg Cr fumes/kg body weight and by repeated (3 times) instillations of 10.8 mg and 21.7 mg Cr fumes/kg. The pathological changes were compared with those induced by single administrations of 3.2 mg and 19.2 mg Na2CO3 solution-insoluble fraction of Cr fumes (Cr-Fr)/kg and 20.8 mg commercially available chromium (III) oxide powder (Cr (III) oxide)/kg. Single and repeated administrations of Cr fumes suppressed growth rate in a dose-dependent manner, but administrations of Cr-Fr and Cr (III) oxide did not. A single administration of Cr fumes produced granulomas in the entire airways and alveoli with progressive fibrotic changes, as well as severe mobilization and destruction of macrophages and foamy cells. Those histopathological changes were aggravated by the repeated administration of Cr fumes. On the other hand, single administrations of Cr-Fr and Cr (III) oxide produced no remarkable histopathological changes. Cr fumes were found to be composed of 73.5% chromium (III) oxide and 26.5% chromium (VI) oxide. The primary particles of Cr fumes and Cr-Fr were similar, 0.02 micron in size (sigma g: 1.25), and Cr (III) oxide particles were 0.30 micron in size (sigma g: 1.53), measured by analytical electron microscopy (ATEM). Diffuse clusters of the primary particles in Cr fumes were identified as Cr (VI) oxide. The present results suggested that the lung toxicity of Cr fumes was mainly caused by these Cr (VI) oxide (CrO3) particles in Cr fumes.

Administration, Inhalation↗
PubMed1999

A new model rat with acute bronchiolitis and its application to research on the toxicology of inhaled particulate matter.

The aim of the present study was to establish a useful animal model that simulates humans sensitive to inhaled particulate matter (PM). We have developed a new rat model of acute bronchiolitis (Br) by exposing animals to NiCl2 (Ni) aerosols for five days. Three days following the Ni exposure, the animals developed signs of tachypnea, mucous hypersecretion, and bronchiolar inflammation which seemed to progress quickly during the fourth to fifth day. They recovered from lesions after four weeks in clean air. To assess the sensitivity of the Br rats to inhaled particles, two kinds of PM of respirable size were tested with doses similar to or a little higher to the recommended threshold limit values (TLVs) for the working environment in Japan. Titanium dioxide (TiO2 = Ti) was chosen as an inert and insoluble particles and vanadium pentoxide (V2O5 = V), as a representative soluble and toxic airborne material. The Br rats exposed to either Ti or V were compared the pathological changes in the lungs and the clearance of particles to those in normal control or Br rats kept in clean air. The following significant differences were observed in Br rats: 1. delayed recovery from pre-existing lesions or exacerbated inflammation, 2. reductions in deposition and clearance rate of inhaled particles with the progress of lesions. The present results suggest that Br rats are more susceptible to inhaled particles than control rats. Therefore, concentrations of particulate matter lower than the TLVs for Japan, which have no harmful effects on normal lungs, may not always be safe in the case of pre-existing lung inflammation.

Acute Disease↗
PubMed1993

Effects of arterial distensibility on left ventricular ejection in the depressed contractile state.

OBJECTIVE: The aim was to evaluate the effects of arterial distensibility on ventricular ejection in various ventricular contractile states: (1) control; (2) a regionally depressed contractile state due to left circumflex coronary artery occlusion (ligation); (3) a globally depressed contractile state induced by lignocaine (lignocaine); and (4) a globally augmented contractile state due to dobutamine infusion (dobutamine). METHODS: Arterial compliance was decreased from 2.3 x 10(-4) dyne-1.cm5 (C2.3) to 0.4 x 10(-4) dyne-1.cm5 (C0.4), maintaining other afterload components and left ventricular end diastolic pressure constant. Nine excised perfused and paced canine hearts, supported from donor dogs, were used. RESULTS: In control, ligation, lignocaine, and dobutamine groups, the difference in cardiac output between the compliance values of C0.4 and C2.3 was 124(SEM 32), 204(36), 163(33), and 130(24) ml, respectively. Thus cardiac output at C0.4, as a percentage of that at C2.3, was 88(2.8)% (control), 75(2.9)% (ligation), 82(2.9)% (lignocaine), and 88(2.4)% (dobutamine), respectively: control v ligation, and lignocaine v ligation, p < 0.001; control v lignocaine, and dobutamine v ligation, p < 0.01. Stroke work at C0.4 decreased in the ligation group (63%, p < 0.001) and in the lignocaine group (70%, p < 0.001). CONCLUSIONS: When cardiac dysfunction is already present, decreased arterial distensibility has a further deleterious effect on cardiac output. This may be due to the fact that the pressure at the end of ejection is higher and as a result the change in dimension during ejection is considerably reduced, especially in cases with depressed cardiac function caused by afterload dependency.

Animals↗
PubMed1993

Evaluation of low-level asbestos exposure by transbronchial lung biopsy with analytical electron microscopy.

To improve diagnostic sensitivity for detecting low-level asbestos exposure (AEx) in patients, a new method was developed using an analytical transmission electron microscope (ATEM) for specimens of transbronchial lung biopsy (TBLB). The TBLB specimens from 28 patients were examined and the results were: 1) In cases with long-term AEx, the present method detected a large amount of asbestos fibers (AF) as well as asbestos bodies (AB) showing a good agreement with the results of light microscope (LM) which detected definite amounts of ferruginous bodies (FB). 2) In cases with short-term or suspected AEx, the LM failed to detect FB in some cases, but an appreciable amount of AF was detected using the present method, and AEx was disclosed through a second close interview. 3) Neither AB nor AF were detected in most of the cases without any dust exposure. Although small amounts of chrysotile fibers were observed in some cases, this might simply reflect the exposure level of urban dwellers. These results show that the ATEM applied to the TBLB specimens promises to confirm low-level AEx in such small specimens even if the patients were unaware of their past AEx.

Adult↗
PubMed1992

Human insulin-specific immunoglobulin G antibody and hypoglycemic attacks after the injection of gold thioglucose.

A 56-year-old woman with granulomas of gold thioglucose in her hips exhibited recurrent bouts of hypoglycemic attacks. The first attack occurred 2 years after the last injection of gold thioglucose, when large amounts of extractable insulin and human insulin-specific antibody were noted in her serum. Histological examination of the resected granulomas showed marked infiltration of lymphocytes, plasma cells, and macrophages containing yellowish-brown granules, which proved to be gold by electron microscopy using X-ray microanalysis. After resection of the granuloma, however, the frequency of the hypoglycemic attacks decreased remarkably as well as the levels of both extractable insulin and human insulin-specific antibody.

Antibody Specificity↗
PubMed1992

Determination of exposure to cobalt and nickel in the atmosphere in the hard metal industry.

Cobalt and nickel, matrices of hard metal, have been shown to be respiratory sensitizers. Airborne dust at hard metal-grinding worksites in a factor with a work-force of about 180 grinders was analysed for cobalt and nickel. The electron-microscopic X-ray microanalysis of airborne dust particles demonstrated that they had the same metallic components as hard metal products. Andersen sampling revealed that 66% of total dust was respirable (< 7 microns). Consecutive personal sampling for individuals indicated log-normally distributed concentrations of total dust and cobalt. Of the workers surveyed, 12% (16 out of 133) were exposed to cobalt at more than 50 micrograms m-3, while 1.5% (two out of 133) were exposed to nickel concentrations of more than 50 micrograms m-3. A correlation between cobalt exposure concentrations and nickel concentrations for individuals was significant and positive. Further improvement of the working environment is necessary because of the hazard caused by exposure to cobalt and nickel.

Air Pollutants, Occupational↗
PubMed1992

Reversible lung lesions in rats due to short-term exposure to ultrafine cobalt particles.

Using an ultrasonic nebulizer, cobalt aerosols (MMAD = 0.76 microns, sigma g = 2.1) were generated from an aqueous suspension of ultrafine metallic cobalt particles (Uf-Co) with a primary diameter of 20 nm. Rats were exposed to Uf-Co aerosols at 2.72 +/- 0.44 mg/m3 for 5 hours (Exp. 1) or at 2.12 +/- 0.55 mg/m3 for 4 days at 5 hours/day (Exp. 2). Only minimum histopathological changes were observed in the lungs in Exp. 1. In Exp. 2, evidence of slight injury was noted, including focal hypertrophy or proliferation of the epithelium in the lower airways, damages of macrophages, intracellular edema of the type I alveolar epithelium, interstitial edema, and proliferation of the type II alveolar epithelium. A new finding in this study was the morphological transformation of some damaged type I cells to the juvenile form, which appeared to indicate the capability of self-repair of this cell type. The return to a juvenile form seemed to be a key response of type I cells during the early process of repair without cell division following non-lethal injury. Cobalt accumulated in the lungs after inhalation and was transferred rapidly to the blood. In conclusion, inhaled Uf-Co induced reversible pulmonary injury even after short-term exposure.

Administration, Inhalation↗
PubMed1992

[Electron-microscopic observations on rat lungs after long term inhalation of diesel emissions--non-neoplastic lesions].

Non-neoplastic lesions in the respiratory organs of rats (F344) were investigated after exposure to heavy and light duty diesel emissions for 30 months. Pathological examinations of the lungs after every 6 months of exposure were performed by light and electron microscopy. Anthracosis caused by the inhaled diesel soot was the main morphological change observed in the lung. Foci of alveoli filled with alveolar macrophages engorged with diesel particles were scattered in the lung parenchyma. Marked changes observed in these areas consisted of intake of diesel particles by type 1 epithelium, hypertrophy and glandular proliferation of type 2 epithelium with many extended microvilli and increased number and size of lamellar inclusion bodies, focal increase of collagen fibers in the interstitium, and infiltration of particle-laden macrophages, neutrophils, mast cells and plasma cells into the interstitium of alveolar septa. Within the alveolar lumina there was marked accumulation of particle-laden macrophages or neutrophils and their debris, as well as laminated or scrolled materials discharged from the type 2 epithelium. The most marked changes observed in the airways were focal shortening of cilia and protrusions of non-ciliated cells, which were attributable mainly to the effects of gaseous components in the diesel exhaust. These morphological changes appeared in all the groups exposed to particle concentrations greater than 1 mg/m3 after 6 months' exposure, and were more marked with increase in particle concentration and with time.

Animals↗
PubMed1989

Mechanical properties of rabbit lung with edema caused by exposure to ozone.

Rabbits were intermittently exposed to ozone (O3) and the mechanical properties of their lungs were studied in order to know details of ventilatory functions in lung injuries caused by this gas. The lungs of rabbits exposed to 2 ppm O3 for 6 hours daily for 3 days showed the earlier stage of edema, and tended to trap air as distending pressure was lowered at the measurement of volume-pressure relationship. In this group of animals, dynamic compliance decreased, pulmonary flow resistance increased, and flow-volume curve obtained by forced deflation showed a definitely altered slope with reduced flows at the latter part of descending limb. On the other hand, the significant change observed in rabbits exposed to 1 ppm O3 for 6 hours daily for 7 days was only the increase in pulmonary flow resistance: the extent was similar to that observed in the former group of rabbits. Light-microscopical study for the airways of O3-exposed rabbits revealed varying degrees of epithelial damages and submucosal edema in the large airways and in terminal and respiratory bronchioles, and thickening of alveolar walls in the proximal alveolar ducts, being much more evident in the former group.

Animals↗
PubMed1987

An emphysema model in rats treated intratracheally with elastase.

Pulmonary functions, morphology, and morphometry were examined in rats at 3, 7, and 10 weeks after a single intratracheal administration of 6.5 units of porcine pancreatic elastase in order to obtain a model of pulmonary emphysema which would be suitable for studying the responses of emphysematous lungs to atmospheric pollutants. Functional residual capacity and residual volume of the elastase-treated rats increased at all the times studied, but their total lung capacity increased only at 7 and 10 weeks compared with those of the saline-treated control rats. The increase in static lung compliance and the decrease in peak flow and maximum flow at 50% of total lung capacity during forced expiration were also observed in all except the 3-week elastase animals. The elastase-treated lungs showed morphological changes characteristic of emphysematous lesions. The increase in mean linear intercept length and the decrease in total alveolar surface area were demonstrated by these elastase-treated lungs. Based on these results, we conclude that an adequate and suitable model of pulmonary emphysema could be obtained in rats 7-10 weeks after treatment with the present dose of elastase.

Animals↗
PubMed1987

Effects of long-term nitrogen dioxide exposure on rat lung: morphological observations.

Rats continuously exposed to NO2 at 0.04, 0.4, and 4.0 ppm for as long as 27 months were submitted to morphological observation and electronmicroscopic morphometry of the lung. At 4 ppm exposure for 9 months, bronchial epithelium showed typical proliferation, which progressed further at 18 months. At this stage, proliferation of type II alveolar epithelium and edematous extension of interstitial tissue were evident and yielded fibrosis at 27 months. At 0.4 ppm, morphological changes in 18-month specimens were still ambiguous, although a tendency toward epithelial changes, as well as interstitial edema of the alveolar wall, was noticed under the electron microscope. Slight but definite alteration of the epithelium became evident after 27 months. At 0.04 ppm there were no remarkable changes throughout the entire exposure period. The morphometry revealed concentration- and duration-dependent increases in arithmetic mean thickness (AMT) of the alveolar wall. At 4 ppm, increase of AMT started as early as 9 months, became significant at 18 months, and showed a slight decrease at 27 months. This decrease was interpreted as a recovery of alveolar epithelium and decreased amount of septal edema, which in turn led to fibrosis. At 0.4 ppm, a slight increase of AMT started at 18 months and extended significantly in 27 months. A similar but insignificant tendency was found even at 0.04 ppm. The morphological alterations were parallel to the concentration and duration of exposure. These findings suggested that an intensive study should be conducted to confirm whether alterations were due to prolonged exposure and/or due to elevated sensitivity of the aged lung.

Animals↗
PubMed1986

A comparison of ST segment deviation and calculated solid angle during acute regional ischemia in the isolated canine heart at precordial, epicardial and intramyocardial lead surfaces.

Although solid angle analysis has been considered to be reasonable for explaining the distribution of ST segment deviation following ischemia, it has not been tested fully, especially for ST segment changes in various sites at different lead surfaces. Thus, we investigated the applicability of solid angle theory to the mechanism of ischemic ST segment deviation at intramyocardial, epicardial and precordial leads. We used seven isolated, coronary perfused, isovolumic contracting canine hearts in a homogeneous cylindrical volume conductor. ST segment potentials from 246 electrodes were continuously measured during left circumflex coronary artery occlusion for five minutes. The ischemic boundary was obtained from a postmortem angiography, and the solid angle subtended by the ischemic boundary was calculated at every electrode site. Despite the difference between epicardial and precordial ST segment potential distributions, there was a high correlation between measured ST segment potential and calculated solid angle at epicardial (r = 0.86 +/- 0.05, 0.77-0.93), precordial (r = 0.93 +/- 0.05, 0.84-0.99), and intramyocardial leads (r = 0.95 +/- 0.03, 0.91-0.99). We conclude that solid angle analysis can be used to approximate the distribution of ischemic ST segment deviation at different lead surfaces in acute ischemia.

Animals↗
PubMed1986

Respiratory diseases in hard metal workers: an occupational hygiene study in a factory.

A hygiene study of a hard metal factory was conducted from 1981 to 1984. All workers exposed to hard metal were medically examined and their exposure to cobalt measured. Eighteen employees had occupational asthma related to exposure to hard metal, a prevalence rate of 5.6%. Nine had a positive bronchial provocation test to cobalt and reactions of the immediate, late, or dual type were elicited. Exposure measurements suggest that asthma may be caused by cobalt at a mean time weighted average concentration below 0.05 mg/m3. Only two of the nine individuals with cobalt asthma had a positive patch test to cobalt. Chest radiographs of three workers showed diffuse shadows of category 1 or over. X ray microanalysis of lung biopsy specimens from two of these three workers showed the presence of tungsten, titanium, cobalt, nickel, and some minerals. One of the two was diagnosed as having pneumoconiosis due to exposure to silica in a steel industry and the other was suspected of having pulmonary fibrosis caused by dust generated from the carborundum wheels used to grind hard metal. There were no cases with interstitial pneumonitis in the factory.

Adult↗
PubMed1986

The influence of changes in the size of ischemic region on ST-segment potential distribution in isolated canine hearts.

In order to investigate how a change in the size of a ischemic region is reflected in ST-segment mapping studies, we produced two different sizes of ischemic regions by occluding proximal or distal portions of the left circumflex artery for five minutes, using ten isolated canine heart preparations. We examined the relationship between the geometry of the ischemic region and ST-segment potential distribution on the epicardial surface and that in the "precordium", in which the heart was suspended. The extent of the ischemic region was reflected differently on epicardial and "precordial" sites, in that the magnitude of epicardial ST-segment elevation decreased (p less than 0.001) while the "precordial" one increased (p less than 0.01). In the epicardium the degree of ST-segment elevation was almost uniform over the ischemic region, whereas in the "precordium" it was maximal at sites overlying the center of the ischemic region and progressively decreased approaching the periphery. However, frequent occurrence of intraventricular conduction disturbance was observed near the center of the ischemic region. As a result, the magnitude of epicardial ST-segment elevation near the center became larger than in the periphery. These results suggest that the classical solid angle theory provides a useful approximation of the ST-segment deflection in very acute ischemic phase, until development of the intraventricular conduction delay.

Animals↗
PubMed1985

A new indirect method for measurement of sinoatrial conduction time and sinus node return cycle.

We developed a new indirect method for the measurement of sinoatrial conduction time (SACT) and the sinus node return cycle (SRC) with a transvenous catheter technique. Two early premature stimuli, at intervals 50 msec longer than the effective refractory period (ERP), were given to the right atrium. These early stimuli were followed by eight constant stimuli. The interval of the constant stimuli was a little shorter than the basic cycle length (BCL). The return cycle A1Ar was measured and plotted on the abscissa; the next interval ArA3, was measured and plotted on the ordinate. This was called the "base point". A new stimulus, A2, was then added to the train of stimulations, first at a point simultaneous with Ar. It was then shifted toward the last constant stimulus at 10-20 msec intervals until A2 met the ERP. The relationship between A1A2 and A2A3 was obtained by the repetition of the procedures with various A1A2 intervals. It had two zones, compensatory and non-compensatory. We postulate that the atriosinus conduction time of the last of the eight stimuli was equal to that of A2 when the stimulus A2 first captured and reset the sinus nodal pacemaker cells, as indicated by the transition point of the two zones. Based on this supposition, SACT and SRC could be measured as the intervals from the base point to the transition point and from the transition point to the eighth stimulus, respectively.

Aged↗