Search PubMed⌕ Search

Biomedical subjects

K Kuroyanagi

Publications and source records attributed to K Kuroyanagi.

At least 73 records · Page 4Linked to original sources
PubMed1990

Performance evaluation of X-ray computed tomography "TCT-700S".

The performance of the CT scanner "TCT-700S" (Toshiba Medical), including noise, spatial and contrast resolution, and exposure, was evaluated. Noise increased as the slice thickness decreased. No matter what the slice thickness, noise was great when the product of tube current and scan speed (described by mAs in the following sentences) was small. Furthermore, the short scan speed caused considerable large noise. Reduction of the mAs value caused remarkable increase in noise when the slice thickness was 1 mm or 2 mm. At combinations of slice thicknesses of 1 mm or 2 mm and 100 mAs, noise was 1-1.5%. When slice thicknesses were measured as the spatial resolution, in the case of a slice thickness of 1 mm, the measurements were 1.6 to 1.8 mm. When high and low contrast resolutions were measured, maximum diameters for the recognition were large as slice thickness became thinner. Although average exposure promised the improvement in the contrast resolution, great exposure increases failed to contribute to such improvement. These performances depended on the exposure. In the case of multiple scanning, average exposures in the field were uniform. However, at a minimum scan speed of 1.8 sec, a three fold discrepancy occurred in exposures observed reciprocally from the left and right sides. Average exposures were also almost the same with slice thicknesses of 10 mm, 5 mm and 2 mm, but with a slice thickness of 1 mm, average exposure was twice as great. This measurement indicates inadequate collimation in the case of a slice thickness of 1 mm. These average exposures were proportional to the mAs value. The radial-exposure profile depended on the position in the columnar object. Although similar average exposures were observed, high peak values were observed on the upper side, but exposure tended to spread at the bottom in the center. This means that the primary x-ray amounts were great in the peripheral region and scattered x-ray amounts were great at the center.

Evaluation Studies as Topic↗
PubMed1990

Digital gray-level transformation for the reduction of redundant shadows in rotational panoramic radiography.

In rotational panoramic radiography, the tomographic motion in combination with a slit scanning method make an image layer wide. But some objects outside the image layer are hard to blur and they result to redundant shadows. The gray-level transformation, as one form of digital image processing for the reduction of these redundant shadows, was evaluated. Two methods, the gamma transformation and the histogram flattening method, were examined. A drum scanner was used as the image scanner. The panoramic image on the x-ray film was turned into an 8 bit digital image on the image memory, which had the size of a 512 x 480 matrix. In rotational panoramic radiography, there are low density and contrast regions where redundant shadows of the cervical vertebrae and the mandibular ramus are superimposed on the tomographic image. The histogram of the gray-level was suppressed for the lower gray-levels. The stretching of this gray-level distribution was effective in the reducing redundant shadows. When processed by gamma transformation, the smaller gamma coefficient below 1.0 clarified the tomographic image, and when processed by the histogram flattening method, the setting of the level (L) value around 64-128 effectively reduced the redundant shadows. However, the effectiveness of both gray-level transformations was greatest in restricted cases in which the area where redundant shadows were superimposed on the tomographic image was comparatively large.

Artifacts↗
PubMed1990

[Unsharpness of redundant shadows of the mandibular ramus region in panoramic tomography. The influence by the first slit width].

In panoramic tomography, redundant shadows of the mandibular ramus overlapping with tomographic images on the opposite side prevent radiological diagnosis. Redundant shadows differ from tomographic images in sharpness, film contrast, and imaging quality. In addition to mismatching of film velocities and X-ray beams, familiar causes of such unsharpness, still another source must be taken into consideration: the influence of varying slit widths. In the past, research has been concentrated on real images defined by McDavid et al.; that is, tomographic images and tomographic blurring images. The present study, however, qualitatively evaluates the unsharpness of redundant shadows of the mandibular ramus, especially with reference to the effects of first-slit width. At the same time, comparisons are made with tomographic images overlapping with redundant shadows of the mandibular ramus region. An orthopantomograph OP5 was employed as the panoramic X-ray apparatus. In the first step of the evaluation, X-ray beam alignments were examined in the horizontal dimension. To evaluate unsharpness of the mandibular ramus, we used regression analysis by the least-squares method and the Nitka method. Horizontal beam alignments and image layers as calculated by McDavid et al. (1985) were applied in setting the aluminum plate. Conclusions 1. In the case of redundant shadows of the mandibular ramus, unsharpness of the posterior margin and the condylar process depends on first-slit width, which is a major influence on imaging quality. 2. Intensity of edge and film contrast exert about equal influences on unsharpness of redundant shadows of the mandibular ramus. Both factors were influenced by the set-up position of the subject. 3. Film contrast exerted a greater influence than edge intensity on unsharpness of overlapped tomographic images. 4. The wider the first-slit width, the greater the indistinct area of redundant shadows of the mandibular ramus and overlapped images. But, for the purposes of diagnosis, maximum slit width is probably between 3 and 5 mm.

Artifacts↗
PubMed1990

[Single dose oral toxicity study of BMY-28100 in juvenile rats and dogs].

In order to investigate the single dose oral toxicity of BMY-28100 in juvenile animals, the drug was administered in single doses to 4-day-old and 14-day-old Crj: CD (SD) rats of both sexes at a dose of 2,000 mg/kg, and to 4-week-old beagle dogs of both sexes at doses of 500, 1,000 and 2,000 mg/kg by oral route. The results obtained are summarized as follows: 1. In rats, decreases of the body weight gain were observed for male and female rats treated with the drug on postnatal day 4 through 5 days and 3 days after dosing, respectively. There were no apparent drug-related toxic signs. No deaths occurred during the observation period. Enlargement of the cecum was found in a few rats of both sexes administered the drug on postnatal day 4 or 14. 2. In dogs, watery-mucous diarrhea observed at 2 to 3 hours after dosing in all dose groups was not dose-related. This finding lasted in some dogs till 4 days after dosing. An increased incidence of emesis was induced in all males at 2,000 mg/kg and all females of all dose groups except one female at 2,000 mg/kg. Body weights increased normally for all dogs, but one male at 1,000 mg/kg showed a transient decrease in food consumption. No drug-related histopathological changes were found. Based upon these results, BMY-28100 at 2,000 mg/kg induced no apparent toxic changes in the present experimental conditions. Therefore, the single dose oral toxicity of the drug in juvenile animals appeared to be very slight and generally similar to that in adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1990

[Four-week repeated dose oral toxicity study of BMY-28100 in juvenile rats].

In order to investigate the repeated dose oral toxicity of BMY-28100 in juvenile rats, the drug was administered orally to 4-day-old Crj: CD(SD) rats of both sexes at daily doses of 250, 750 and 1,500 mg/kg for 4 weeks. The results obtained are summarized as follows: 1. Soiling around the anus apparently correlated to soft stool or diarrhea was observed at 750 and 1,500 mg/kg and the incidence appeared to be dose-related. Three deaths including 1 death due to cannibalization occurred at 750 and 1,500 mg/kg, but they were considered to have been caused by misadministration. 2. Slightly depressed body weight gains were noted in the 750 and 1,500 mg/kg dose groups during early dosing period. 3. Slightly increased averages of food and water consumption observed predominantly in the 1,500 mg/kg dose group at later dosing period and the recovery period were considered as incidental and unrelated to the treatment. 4. Though average values of some blood chemical parameters were slightly suppressed or elevated compared with those of controls at the completion of the dosing and recovery periods, these differences appeared to be generally within normal ranges and to be irrelevant to the drug treatment. No definitive drug-related changes were detected in hematological examinations and urinalyses. 5. The average absolute and/or relative organ weights of the brain, thymus, lungs and liver from male rats in the 1,500 mg/kg dose group were lower than those of the corresponding organs from controls. However, these findings were not considered to be toxicologically significant because no corroborative changes were detected microscopically. 6. Macroscopic and microscopic examinations demonstrated dilatation of the cecum in a dose-related fashion. This phenomenon has been reported with other antibiotics and appears to be drug-related and reversible caused by an alteration of the gut flora. There were no other microscopic changes that were considered to be related to the administration of the drug. 7. Electron microscopic examination revealed no drug-related changes in the liver and kidneys from rats of the 1,500 mg/kg dose group. Based upon these results, the no-effect dose level of BMY-28100 was estimated to be 250 mg/kg/day for both male and female juvenile rats in the 4-week repeated dose oral toxicity study if the finding of cecum dilatation was not considered.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Oral↗
PubMed1989

Objective and subjective comparisons of the observation of dental xeroradiographs with reflected and transmitted light.

One of the advantages of dental xeroradiography is that the radiographs may be viewed by either reflected or transmitted light. Both objective and subjective evaluations were carried out to evaluate which viewing method was more efficient. The components of contrast, resolution, and noise were compared by objective physical evaluation. The subjective evaluation measured the visibility of radiographic details. All results of the objective evaluation indicated an advantage for observation with reflected light. On the other hand, the subjective evaluation with transmitted light demonstrated better detectability. The discrepancy of these results could be explained by the difference in the amount of incident light on the radiographs, when a comparison was made of the same subjective evaluation under intense reflected light with the use of slide projectors.

Densitometry↗
PubMed1988

[Reproduction studies of carboplatin (I)--Intravenous administration to rats prior to and in the early stages of pregnancy].

Carboplatin, an oncostatic drug, was administered intravenously to male Crj: CD (Sprague-Dawley) rats for 63 days and to female rats of the same strain for 14 days prior to mating at dose levels of 1, 2 and 4 mg/kg/day. These animals were then mated under the consecutive administration of this drug and the females confirmed to be copulated were further dosed from day 0 through 7 of gestation. The summarized results obtained are as follows: 1. Carboplatin 2 mg/kg and higher suppressed body weight gains accompanied by the decreases in food and water consumption in male rats. Further, body weight gains were suppressed in female rats followed by the decreases in food consumption at the same dose levels. 2. Though there were no differences between dosed animals and controls regarding the organ weights, the incidence of necrosis of the tails around the injection site was increased in male rats at 4 mg/kg. 3. Carboplatin failed to affect the reproductive ability of both sexes. 4. As for fetuses, the mortality was elevated at 2 mg/kg and higher and the number of live fetuses reduced at 4 mg/kg, but the influences on prenatal development were not apparently observed for live fetuses even at the highest dose level. Based on these results, the no-effect dose level of carboplatin under the present experimental condition was estimated to be 1 mg/kg/day against parent rats of both sexes and their offspring.

Animals↗
PubMed1988

[Reproduction studies of carboplatin (II)--Intravenous administration to rats during the period of fetal organogenesis].

Carboplatin, an oncostatic drug, was administered intravenously to pregnant Crj: CD (Sprague-Dawley) rats from day 7 through 17 of gestation at dose levels of 1, 2 and 4 mg/kg/day. The summarized results obtained are as follows: 1. Carboplatin 4 mg/kg suppressed the maternal body weight gains from day 13 through 20 of gestation. 2. Uterine weights were reduced in F0 dams at term at carboplatin 4 mg/kg. 3. Carboplatin 4 mg/kg brought the inhibition of fetal growth accompanied by the lowered values in fetal weights, crown-rump distances and tail lengths. Furthermore, the elevated incidences of unossified 5th and 6th sternum , as well as retarded ossification of sacrococcygeal vertebrae were also noted in this dose level. 4. The birth rate was reduced in neonates (F1) at carboplatin 4 mg/kg. 5. Body weight gains in male F1 rats were suppressed at carboplatin 4 mg/kg from 4 to 8 weeks of age. 6. Carboplatin 4 mg/kg decreased the brain weights on an absolute basis in female F1 rats, but failed to affect their postnatal differentiations, early behavioral developments, learning ability, motor activity or emotional development. 7. Reproductive ability in F1 rats of both sexes were not affected by carboplatin. 8. Influences on prenatal development were not apparently observed for F2 fetuses derived from F1 rats whose dams had ever received carboplatin during the organogenetic period. Based on these results, the no-effect dose level of carboplatin under the present experimental condition was estimated to be 2 mg/kg/day against dams and their offspring.

Animals↗
PubMed1988

[Reproduction studies of carboplatin(III)--Intravenous administration to rats during the perinatal and lactation periods].

Carboplatin, an oncostatic drug, was administered intravenously to pregnant Crj: CD (Sprague-Dawley) rats from day 17 of gestation through day 21 of postpartum at dose levels of 1, 2 and 4 mg/kg/day. The summarized results obtained are as follows: 1. Maternal body weight gains were suppressed during the former part of the lactation period at carboplatin 2 mg/kg and higher. 2. Thymic weights were decreased and lung weights were increased in dams (F0) at carboplatin 2 mg/kg and higher. Further, ovarian weights were reduced in dams (F0) at carboplatin 4 mg/kg. 3. Carboplatin failed to affect the parturition of F0 dams. 4. Carboplatin did not affect the viability of newborns (F1), and postnatal differentiations, early behavioral developments, learning ability, motor activity or emotional development in F1 animals. 5. Carboplatin 4 mg/kg brought a suppression of pituitary weights after mating in F1 male rats and decreases of adrenal and genital organ weights at weaning in F1 female rats, but failed to affect their reproductive ability. 6. Influences on prenatal development were not apparently observed for F2 fetuses derived from F1 rats whose dams had ever received carboplatin during the perinatal and lactation periods. Based on these results, the no-effect dose level of carboplatin under the present experimental condition was estimated to be 1 mg/kg/day against dams and 2 mg/kg/day against their offspring.

Adrenal Glands↗
PubMed1986

[Toxicity studies of VP 16-213 (I)--Acute toxicity in mice, rats and rabbits].

VP 16-213 (etoposide, abbr. to VP), an oncostatic drug, was examined for its oral, subcutaneous or intravenous acute toxicity using Slc : ICR mice, Crj : CD (Sprague-Dawley) rats and JW-NIBS rabbits of both sexes. The summarized results obtained are as follows: A mode of manifestation of toxic effects was classified into immediate-type symptoms predominantly caused by the carrier and delayed-type symptoms predominantly caused by VP regardless of animal species and routes of administration, excluding the case of intravenous dosing to rabbits. Referring to the delayed-type toxic signs, depilation, diarrhea and suppression of body weight increase were observed for mice and rats regardless of administration routes, and diarrhea was noted in rabbits by oral route. Necropsy of three species of animals and histopathology on rabbits revealed thymic and splenic atrophy in mice and rats as well as thymic atrophy and inflammatory changes of intestine in rabbits dying by oral administration. The drug-related cause of death for mice and rats seemed to be due to the cytocidal action of VP as an oncostatic drug, but the cause of death for rabbits by oral administration was considered to be somewhat different from that for mice and rats. LD50 values (mg/kg) were as follows, showing oral toxicity in rabbits being rather potent as compared with that in mice or rats: (table; see text).

Administration, Oral↗
PubMed1986

[Toxicity studies of VP 16-213 (V)--Intravenous three-month toxicity in rats].

VP 16-213 (etoposide, abbr. to VP), an oncostatic drug, was administered intravenously to Crj : CD (Sprague-Dawley) rats of both sexes at dose levels of 0.05, 0.15, 0.5 and 1.5 mg/kg/day for three months with the object of examining its toxicity and the reversibility of toxic effects. For the purpose of comparison, vincristine (abbr. to VCR) was administered in the same manner at a dose level of 0.02 mg/kg/day. The summarized results obtained are as follows: VP 1.5 mg/kg brought anemia as well as suppression of body weight increase and food intake, and 0.5 and 1.5 mg/kg increased water consumption. However, no drug-related deaths occurred. VP 0.5 and 1.5 mg/kg predominantly decreased red blood cell count and white blood cell count accompanied with lowered lymphocyte fraction which was agreeable to the findings on bone marrow. VP 1.5 mg/kg increased platelet count. VP 1.5 mg/kg lowered total serum protein content and elevated A/G ratio. VP 0.15 mg/kg and higher decreased testicular weight; 0.5 and 1.5 mg/kg brought thymic atrophy, suppression of spermatogenesis, tubular atrophy and hydropic change in testis. VP 1.5 mg/kg induced decrease of sperms in number and appearance of giant cells in epididymis. Above-described changes excluding the findings on testis and epididymis were shown to be generally reversible. Most of the findings for a reference drug, VCR, were qualitatively comparable to those for VP. Based on these results, the non-effect dose level of VP under the present experimental condition was estimated to be 0.05 mg/kg/day against male rats and 0.15 mg/kg/day against female rats.

Anemia↗
PubMed1986

[Toxicity studies of VP 16-213 (II)--Oral one-month subacute toxicity in rats].

VP 16-213 (etoposide, abbr. to VP), an oncostatic drug, was administered orally to Crj : CD (Sprague-Dawley) rats of both sexes at dose levels of 3, 10, 30 and 100 mg/kg/day for one month with the object of examining its subacute toxicity and the reversibility of toxic effects. The summarized results obtained are as follows: VP 30 mg/kg suppressed body weight increase and feed intake, and brought soft stool. VP 100 mg/kg decreased body weight and feed intake, and induced diarrhea, depilation and so forth. Furthermore, half of the animals at this dose level died showing systemic debility and emaciation. VP 30 and 100 mg/kg predominantly decreased red blood cell count as well as white blood cell count accompanied with lowered lymphocyte fraction. VP 10 mg/kg and higher lowered total serum protein content and serum alkaline phosphatase activity, and elevated A/G ratio. VP 10 mg/kg and higher caused thymic atrophy and a decrease in testicular weight; 30 and 100 mg/kg brought suppression of spermatogenesis; and 100 mg/kg predominantly induced appearance of giant cells in epididymis, hypoplasia of bone marrow, ileocecitis, and atrophy of prostate, seminal vesicle and splenic germinal centers. Above-described changes excluding exacerbation of the findings on testis and epididymis were shown to be generally reversible. Based on these results, the no-effect dose level of VP under the present experimental condition was estimated to be 3 mg/kg/day against rats of both sexes.

Administration, Oral↗
PubMed1986

[Reproduction studies of VP 16-213 (I)--Oral administration to rats prior to and in the early stages of pregnancy].

VP 16-213 (etoposide, abbr. to VP), an oncostatic drug, was administered orally to male Crj : CD (Sprague-Dawley) rats for 64 days and to female rats of the same strain for 15 days prior to mating at dose levels of 1, 3 and 10 mg/kg/day. These animals were then mated under the consecutive administration of this drug and the females confirmed to be copulated were further dosed from day 0 through 7 of gestation. The summarized results obtained are as follows: VP 10 mg/kg suppressed the body weight increase in females from day 8 of pre-mating through day 20 of gestation, but did not affect the body weight in males. VP 10 mg/kg decreased the organ weights of testes, epididymides and thymus in males and induced atrophy of these organs macroscopically, but did not affect their reproductive performances. As for fetuses, VP 10 mg/kg elevated the mortality and induced anophthalmia, microphthalmia and dilated lateral ventricles, as well as suppressed their growth and the ossification processes of sternums, sacral and coccygeal vertebrae, metacarpus, thoracic vertebrae and pubis. Based on these results, the no-effect dose level of VP under the present experimental condition was estimated to be 3 mg/kg/day against parent rats of both sexes and their offspring.

Administration, Oral↗
PubMed1986

[Reproduction studies of VP 16-213 (II)--Oral administration to rats during the period of fetal organogenesis].

VP 16-213 (etoposide, abbr. to VP), an oncostatic drug, was administered orally to pregnant Crj: CD (Sprague-Dawley) rats from day 7 through 17 of gestation at dose levels of 1, 3 and 10 mg/kg/day. The summarized results obtained are as follows: VP 10 mg/kg suppressed the maternal body weight increase from day 12 through 20 of gestation. VP 10 mg/kg brought the inhibition of fetal growth accompanied by the lowered values in body weight and body length. Furthermore, the elevated incidences of skeletal anomalies and unossified 5th and 6th sternums, as well as retarded ossification of thoracic vertebrae were also noted in this dose level. VP 10 mg/kg induced anophthalmia, microphthalmia and dilated lateral ventricles in fetuses (F1), as well as unilateral anophthalmia in offspring (F1). VP 10 mg/kg increased the days required for opening of eyelids and descending of testes in offspring (F1), but failed to affect their learning ability, motility, motor activity or emotional development. VP 10 mg/kg suppressed the growth of genital organs in F1 rats of both sexes, but failed to affect their reproductive ability or gestation period. As for F2 newborns derived from F1 rats whose dams had ever received VP 10 mg/kg during the period of fetal organogenesis, the number of implantations and survivors as well as birth indexes lowered due to changes in these items restricted to a few litters. Based on these results, the no-effect dose level of VP under the present experimental condition was estimated to be 3 mg/kg/day against dams and their offspring.

Administration, Oral↗
PubMed1986

[Reproduction studies of VP 16-213 (III)--Oral administration to rabbits during the period of fetal organogenesis].

VP 16-213 (etoposide, abbr. to VP), an oncostatic drug, was administered orally to pregnant JW-NIBS rabbits from day 6 through 18 of gestation at dose levels of 0.3, 1, 3 and 10 mg/kg/day. The summarized results obtained are as follows: VP 3 and 10 mg/kg elevated the maternal mortality dose-responsively. VP 3 mg/kg and lower doses failed to affect the fetal growth and ossification processes, and did not induce drug-dependent external and visceral anomalies as well as skeletal variations and anomalies. Based on these results, the no-effect dose levels of VP under the present experimental condition were estimated to be 1 mg/kg/day against dams and 3 mg/kg/day against fetuses.

Administration, Oral↗