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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 829 records · Page 46Linked to original sources
PubMed1977

Improved cold tolerance and its mechanism in cold-acclimated rats by high fat diet feeding.

Cold tolerance and metabolic responses to cold were studied in cold-acclimated rats on high fat diet (CAHF). Cold tolerance at-5 degrees C was assessed by fall of colonic temperature of clipped rats after 18 h of fasting. Rate of fall in colonic temperature was greatest in warm-acclimated control rats (WAST), slowest in cold-acclimated rats on standard diet (CAST), and remained unchanged in CAHF during cold exposure for 240 min. Increment in blood free fatty acid (FFA) concentration 80 min after cold exposure was greatest in WAST, less in CAST, and least in CAHF. Blood glucose decreased similarly in WAST and CAST after cold exposure, while it remained unchanged in CAHF. Blood beta-hydroxybutyrate also increased similarly in WAST and CAST, while it did not change in CAHF. Nonshivering thermogenesis tested by noradrenaline was greatest in CAHF, followed by CAST and WAST. Shivering induced by cold exposure was less pronounced in CAST than in WAST and did not develop in CAHF; changes in colonic temperature were inversely related to the extent of shivering during cold exposure for 90 min. These results suggest that an integrating effect of cold and high fat diet could improve cold tolerance much more than cold acclimation itself, possibly through enhanced nonshivering thermogenesis caused by metabolic modifications such as increased lipid use and gluconeogenesis.

Acclimatization↗
PubMed1977

Reduced hyperglycemic action of glucagon in cold-acclimated rats, especially in venous drainage from brown adipose tissue.

Glucagon infusion at a rate of 2 microgram/min for 30 min into warm-acclimated rats induced a marked rise of glucose concentration in venous blood both in the external jugular vein and in Sulzer's vein from the interscapular brown adipose tissue. In cold-acclimated rats the increase in the concentration of glucose was significantly reduced in the former vein and abolished in the latter one. These results suggest an enhanced use of glucose in the brown adipose tissue in cold-acclimated animals under the influence of glucagon.

Acclimatization↗
PubMed1977

Noise reduction by radiographic magnification.

Effective noise in the rare-earth system can be substantially reduced by use of radiographic magnification technique. The basic imaging properties of the rare-earth system (Alpha 8-XM) and the medium-speed system (Par-RP) were evaluated by the Wiener spectra, modulation transfer functions, and H&D curves. The visibility of radiographic details was determined with simple test objects. Results indicate that, as the magnification increases, the effective noise in the rare-earth system is reduced, and that the visibility of small structures can be improved.

Models, Anatomic↗
PubMed1977

Direct radiographic magnification for skeletal radiology. An assessment of image quality and clinical application.

Recent advances in technology have made radiographic magnification of the skeleton clinically feasible. A new electron gun micro-focal tube combined with new high-resolution recording systems were used to perform magnification radiography which was then compared with conventional contact radiography. Quantitative evaluation included measurements of speed, contrast, resolution, and noise. Qualitative evaluation included an analysis of 215 clinical cases in which both techniques were used. The superior image quality of direct radiographic magnification is confirmed and the clinical areas in which it proved most helpful are defined.

Arthritis↗
PubMed1977

Application of longitudinal magnification effect to magnification stereoscopic angiography: a new method of cerebral angiography.

A new method of stereoscopic cerebral angiography has been developed which employs 2X radiographic magnification. In order to obtain the same depth perception in the object as with conventional contact stereoscopic angiography, one can made the x-ray exposures at two focal spot positions which are separated by only 1 inch (2.5 cm), whereas the contact technique requires a separation of 4 inches (10 cm). The smaller distance is possible because, with 2X magnification, the transverse detail in the object is magnified by a factor of two, but the longitudinal detail, which is related to the stereo effect, is magnified by a factor of four, due to the longitudinal magnification effect. The small focal spot separation results in advantages such as improved stereoscopic image detail, better image quality, and low radiation exposure to the patient.

Cerebral Angiography↗
PubMed1977

Determination of X-ray spectra incident on and transmitted through breast tissue.

X-ray spectra incident on and transmitted through breast tissue were measured using a fresh whole excised breast. These spectra and corresponding radiographs show that hardening of the beam from a molybdenum-anoda x-ray tube by a 0.5-mm AI filter instead of the conventional 0.03-mm Mo filter allows shorter exposure times and reduces patient exposure. Acceptable image contrast is preserved in mammography of thick or dense breasts.

Female↗
PubMed1977

Magnification film mammography: image quality and clinical studies.

Direct radiographic magnification (1.5 X) of the breast with a microfocus x-ray tube was compared with conventional contact mammography. Measurements of modulation transfer functions, Wiener spectra, scattered radiation, and dosimetry permitted quantitative comparisons of resolution, noise, contrast, and patient exposure. Images of surgical specimens of the breast, and the breasts of 125 patients, were qualitatively compared. Magnification images were superior (increased resolution, reduced noise) to conventional mammography images, at the expense of increased radiation dose. Clinical study revealed that the superior magnification image is useful in distinguishing malignant from benign breast disease, in selected cases.

Breast Neoplasms↗
PubMed1977

Image quality in mammography.

Image quality in mammography is affected by the shape, size, and x-ray absorption properties of the anatomic part or lesion to be radiographed in addition to x-ray beam quality, geometric unsharpness, and the resolution, characteristic curve, and noise properties of the recording system. The authors review x-ray energy spectra, modulation transfer functions. Wiener spectra, characteristic and gradient curves, and radiographs of a breast phantom and a resected breast specimen containing microcalcifications; these factors, and the complex relationship between them, affect image quality and patient radiation exposure. Evaluation of the best system or technique for obtaining a breast image is discussed in terms of the compromise between diagnostic certainty and cost or risk.

Breast Neoplasms↗
PubMed1977

Screen/film system speed: its dependence on x-ray energy.

Dependence of the speed of various screen/film systems on x-ray energy was studied using the nearly monoenergetic x rays emitted by a filtered fluorescent source. The results show that response depends on screen phosphor composition and thickness. Barium and rare earth screens having K absorption energies lower than that of calcium tungstate are relatively more sensitive to x rays in the 40-70-keV region.

Technology, Radiologic↗
PubMed1977

Bone grafts with microvascular anastomoses of vascular pedicles: an experimental study in dogs.

Using microvascular anastomoses of artery and vein, bone grafts with vascular pedicles from the rib were transferred to inlay and bridge defects in the femora of forty-two dogs. The osteocytes of the pedicle graft were not affected, and neither necrosis nor creeping substitution occurred in the grafted bone. The pedicle bone grafts united to the recipient bed earlier than did the non-pedicle bone grafts, and the rate of non-union of the pedicle bone grafts was lower than that of the non-pedicle grafts.

Angiography↗
PubMed1976

Seasonal variation of urinary excretion of total metanephrines.

Results of 1414 measurements of urinary excretion of free and conjugated (total) metanephrine and normetanephrine (total metanephrines, tMN) and of 1630 measurements of vanilmandelic acid (VMA) excretion were analysed according to the month of sample collection. These collections had been carried out as a part of a study of hypertension at out institute over the 5-year period between 1970 and 1975. The means and scatters of tMN were significantly varied depending on the season of the year; the mean during 3 months of summer was 380 mug/day and the mean for 3 winter months 800 mug/day. The scatter of tMN in winter months was wider. A minor seasonal variation was observed for VMA: the means of summer and winter months were 3.8 mg/day and 4.5 mg/day, respectively. The results suggest a seasonal difference of catecholamine catabolism.

Epinephrine↗
PubMed1976

Is glucagon involved in cold acclimatization?

Cold acclimatization in rats at 5 degrees C for 2 weeks caused a significant elevation of plasma glucagon concentration, accompanied by increased plasma FFA and glucose levels. Acute cold exposure at 5 degrees C for 5 or 60 min did not affect these parameters in plasma.

Acclimatization↗
PubMed1976

The influence of thyroxine on the serum free triiodothyronine concentration.

By means of measurement of the serum free triiodothyronine fraction (%FT3) by equilibrium dialysis, the influence of varying serum concentrations of thyroxine (T4) on %FT3 was studied in conditions associated with lack or excess of serum T4 and in serum enrichment with T4 in vitro. The enrichment of pooled serum with T4 caused significant increases of %FT3 with T4 was added to elevate its T4 content between 10 and 25 mug/dl. In 4 subjects with primary hypothyroidism treated with T3 (25 mug once daily for two weeks, twice daily thereafter), progressive increases of serum T3 were observed while their T4, free T4 and T3 fractions remained unchanged. Consequently, the serum free T3 and thyrotropin concentrations became normal after the serum T3 concentrations became hypernormal. When comparisons of the serum thyroid hormone levels were made between 6 subjects with T3 toxicosis and 8 with a usual variety of hyperthyroidism matched for serum T3 concentration, the former sub-group of hyperthyroidism showed significantly lower serum free T3 concentration (0-51 +/- 0.22 ng/dl versus 0.79 +/- 0-21 ng/dl, p less than 0.05). The amount of T4 in serum is considered to affect its free T3 concentration by virtue of sharing serum-binding proteins.

Humans↗