Biomedical subjects

Y J Yoon

Publications and source records attributed to Y J Yoon.

5 recordsLinked to original sources

PubMed1992

Optimum comfort limits determination through the characteristics of asymmetric thermal radiation in a heated floor space, "ondol".

This study was undertaken to evaluate the effects of the asymmetric radiation on thermal comfort, and to suggest the optimum comfort limits in a radiant heating space. The index of V.R.T. (Vector Radiant Temperature) was used to describe the environmental quality of the heated floor space. Optimum comfort limits of this space were suggested through both theoretical and empirical studies. It is recommended to use not only man's sensation of the ambient air but also that of the floor surface for the determination of the optimum comfort limits on the heated floor space such as an "Ondol" in Korea. In the present study the optimum comfort limits were suggested in terms of the V.R.T. The optimum limits obtained were as follows: the vector radiant temperature 11.0 approximately 15.0 K.

Floors and Floorcoverings↗

PubMed1992

Immunohistochemical localization of alpha-atrial natriuretic polypeptide in the rat cochlea.

The localization of alpha-atrial natriuretic polypeptide (alpha-ANP) in the rat cochlea was studied by immunohistochemical technique, using a polyclonal antibody against synthetic rat alpha-atrial natriuretic polypeptide (alpha-rANP). The spiral ligament of the lateral cochlear wall exhibited pronounced immunoreactivity to atrial natriuretic polypeptide (ANP), whereas the stria vascularis displayed almost no immunoreaction. ANP immunoreactivity (IR) was also intense in the spiral limbus region. IR was observed in the fibroblast-like cells and in the extracellular matrix, in particular along its fibrous bundles, of both the spiral ligament and the spiral limbus. These results indicate that ANP may participate in the regulation of the water electrolyte balance at these sites, which may imply a role for ANP in the regulation of cochlear fluids.

Animals↗

PubMed1991

Ultrasonic phased array controller for hyperthermia applications.

Multiple and mechanically scanned ultrasound transducer systems have demonstrated the efficacy of using ultrasound to produce deep localized hyperthermia. The use of ultrasonic phased arrays has been proposed as an alternative to these systems. A phased array offers a more flexible approach to heating tumours in that the size, shape, and position of its focal region can be altered during the course of treatment in order to achieve the desired temperature distribution. This added flexibility comes at the cost of increased complexity of the hardware necessary to drive the transducer because each element requires its own amplifer with both phase and amplitude control. In order for phased arrays with large numbers of elements to be feasible for hyperthermia applications, the complexity of this circuitry must be minimized. This paper describes a circuit design which simplifies the electronics required to control a phased array transducer system for hyperthermia applications. The design is capable of controlling virtually any type of phased array transducer operating at frequencies less than 2 MHz. The system performance was verified through beam profile measurements using a 48-element tapered phased array transducer.

Hyperthermia, Induced↗

PubMed1981

Fetal macrosomia in experimental maternal diabetes.

Fetal macrosomia in diabetic pregnancy has been shown to accompany increases in the fetal levels of deoxyribonucleic acid (DNA) and proteins in animal model systems. In order to elucidate the underlying mechanisms of this macrosomia, the synthesis of DNA and proteins, the transport of the precursors, and the tissue level of DNA polymerase activities in macrosomic fetuses from mildly diabetic rats were compared with those in normal fetuses on 20.5 and 19.5 days of gestation. Increases in the influx of precursors and stimulation of synthesis of the macromolecules were observed in macrosomic fetuses as early as 19.5 days of gestation. However, stimulation of DNA polymerase activities in macrosomic fetuses did not occur until 20.5 days of gestation. Therefore, stimulation of DNA polymerase may participate in maintenance of macrosomia but does not initiate macrosomia. Whether or not increases in both the influx of substrates and the synthesis activities precede the macrosomia has yet to be determined.

Animals↗

PubMedDate not supplied

Distribution of hyaluronan in the middle and inner ear. A light microscopical study in the rat using a hyaluronan-binding protein as a specific probe.

The histochemical distribution of hyaluronan (hyaluronic acid, HYA) was analyzed in middle and inner ear tissues from rats by use of microwave-aided fixation, a hyaluronan-binding protein and the avidin-biotin/peroxidase staining procedure. In the middle ear HYA was mainly localized in the pars flaccida, the ossicles, the round window membrane and in the endomysium of the middle ear muscles. The subepithelial stroma of the Eustachian tube was strongly HYA-positive. In the inner ear, the spiral ligament of the cochlea and the connective tissue surrounding the nerve fibers emerging from the crista ampullaris stained intensely for HYA. Except for a weak staining of the basilar membrane, the Corti organ was devoid of HYA. The heterogenous distribution of HYA may indicate its specific involvement in middle and inner ear physiology and pathology.

Animals↗