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Biomedical subjects

K Kasai

Publications and source records attributed to K Kasai.

At least 217 records · Page 12Linked to original sources
PubMed1994

Melanocytes fail to survive in hair bulbs of the Shiba goat (Capra hircus) with the dominant black-eyed white phenotype.

Dominant black-eyed white phenotypes are one of the most commonly observed traits in domestic animals. Their genetic control mechanisms, however, have not been elucidated. As the first step to approach the problem, we examined histologically the patterns of the distribution of pigment cells in Shiba goats (two each of day-73-postcoitum and day-112-postcoitum fetuses, and a 15-week-old kid) with the dominant black-eyed white phenotype. Melanocytes were present and fully pigmented in the choroid and the sclera of eyes, as well as in dorsal skin epidermis of the fetuses and of the kid. Melanocytes were also found in approximately 6% of the hair bulbs in the fetal dorsal skin, while the rest (94%) lacked them. Hair follicles of the kid did not harbor melanocytes except for some in the early anagen stage. The results suggest that the survival of melanocytes was inhibited specifically in the hair follicles of the Shiba goat with the dominant black-eyed white phenotype and that the ostensibly similar phenotypes in the Shiba goat and in the S1 or W mutants of the mouse, where melanocytes die en route to the hair bulbs, are regulated by different mechanisms.

Animals↗
PubMed1994

Mathematical analysis and experiment on the corneal reflex test in spectacle wearers.

An experimental study and mathematical analysis of the corneal reflex test was undertaken in spectacle wearers. In the experimental study, photographs were taken of the corneal reflex through spectacles and the conversion ratios determined as measured in degrees/mm. In the mathematical analysis, the magnification effect of the lens was elucidated by three methods: geometrical analysis; real measurement of magnification factor; and ray tracing analysis. The real measurement of the conversion ratios was in good agreement with the conversion ratios determined by the three mathematical analyses. These results clearly showed that the corneal reflex test can be clinically useful even in wearers of spectacles.

Blinking↗
PubMed1994

Relationship between attachment of the superficial masseter muscle and craniofacial morphology in dentate and edentulous humans.

Previous studies have described the importance of the interaction between the masticatory muscles and the craniofacial skeleton in the control of craniofacial growth. This study describes the attachment and orientation of the superficial masseter muscle and its relationship with craniofacial morphology in dentate and edentulous subjects. Data were obtained from lateral cephalometric radiographs of a total of 31 cadavers in which the superficial masseter muscle had been defined with liquid barium. The results provide evidence that the morphology of the superficial masseter muscle in the gonion region differed significantly between dentate and edentulous subjects, with the masseter being 2.7 mm wider and the gonion-anterior muscle border distance being 4.0 mm greater in dentate subjects. The complex relationship between craniofacial morphology and the dimensions and inclination of the superficial masseter muscle were most clearly evident in dentate subjects where the position of the anterior border was related to ramus dimensions and mandibular and occlusal plane angles. The association is much less clear in edentulous subjects where normal function was disturbed. In general, age was not a significant determinant of variation in superficial masseter muscle dimensions and orientation.

Age Factors↗
PubMed1994

Growth regulation of the human papillary thyroid cancer cell line by protein tyrosine kinase and cAMP-dependent protein kinase.

We established a cell line (hPTC) from the tissue of papillary thyroid cancer surgically excised from a 27-year-old female patient. Synthesis of cAMP by the hPTC cells was stimulated by TSH. This cell line has continued to divide as a monolayer in a tissue culture for three years. We assessed growth regulation of the hPTC cells by protein tyrosine kinase and cAMP-dependent protein kinase by measuring the DNA content of the hPTC cells in 24-well plates with 3,5-diaminobenzoic acid after incubation in various growth factors. Basic fibroblast growth factor (FGF), epidermal growth factor (EGF), and insulin-like growth factor-1 (IGF-1), all of which bind to their respective receptors with tyrosine kinase activity, stimulated DNA synthesis in the hPTC cells. Neutralizing antibodies to basic FGF and EGF suppressed the growth stimulation by basic FGF and EGF, respectively. Genistein, a specific protein tyrosine kinase inhibitor, inhibited proliferation of the hPTC cells. On the other hand, thyrotropin, dibutyryl cAMP (dBC) and forskolin inhibited proliferation. KT5720, a specific cAMP-dependent protein kinase inhibitor, restored the growth of the hPTC cells even in the presence of dBC. This study shows that stimulation of the protein tyrosine kinase activity by basic FGF, EGF, and IGF-1 promoted DNA replication by the human thyroid cancer cell line. However, activation of the cAMP-dependent protein kinase inhibited proliferation of this cell line.

Adult↗
PubMed1994

[A case of venous angioma complicated by unruptured aneurysm with TIA as the initial manifestation].

Venous angioma is a relatively rare vascular malformation of the brain. It is usually asymptomatic and may be an incidental finding at autopsy or on cerebral angiography. We report a very rare case in which TIA-like attack occurred as the initial manifestation. A 59-year-old woman was hospitalized because of a TIA-like attack about 5 months after left putaminal bleeding. Detailed examination allowed us to make a diagnosis of subcortical venous angioma of the left parietal lobe and multiple cerebral aneurysms. The cerebral aneurysms were treated surgically. Since the angioma was localized in an eloquent area, radiotherapy was chosen first. Angioma giving rise to TIAs is very rare. The ischemia may have been caused by transient venous thrombosis or a steal phenomenon due to a decrease in blood circulation in the left cerebrum caused by the putaminal bleeding.

Brain Neoplasms↗
PubMed1994

[Thyroxine-binding proteins--familial euthyroid hyperthyroxinemia due to point mutations of transthyretin].

Some of the point mutations in transthyretin (TTR) exhibit increased affinity for thyroxine (T4) and result in euthyroid hyperthyroxinemia in affected individuals. TTR, also known as thyroxine binding prealbumin, is a homotetrameric plasma protein of MW 55,000 that transports 15% of serum T4. The known point mutations that cause euthyroid hyperthyroxinemia are Ala109 (ACC) to Thr (GCC) and Gly6 (GGT) to Ser (AGT). These mutations are transmitted by autosomal dominant inheritance. The laboratory findings are an elevated total T4, an increased free T4 index, a normal free T4, and normal levels of total and free triiodothyronine. The Thr109 mutation abolishes Fnu4HI restriction site, and the Ser6 mutation eliminates the Msp I restriction site.

Diagnosis, Differential↗
PubMed1993

Effect of NG-nitro-L-arginine on shock induced by endotoxin and by platelet activating factor in dogs.

When NG-nitro-L-arginine, a nitric oxide synthase inhibitor, administration was started 5 min prior to shock induction in anesthetized dogs, a partial restoration was observed in endotoxin-induced shock and a complete recovery in platelet activating factor (PAF)-induced shock. When NG-nitro-L-arginine infusion was started 5 min after shock induction, no significant recovery was observed in endotoxin-induced shock and a complete recovery in PAF-induced shock. These data indicate that enhanced production of nitric oxide by vascular endothelial cells may contribute to endotoxin- or PAF-induced shock and also that some mediators including inducible nitric oxide synthase and/or cellular damage might be involved in endotoxin-induced shock.

Amino Acid Oxidoreductases↗
PubMed1993

A mutation of furin causes the lack of precursor-processing activity in human colon carcinoma LoVo cells.

Furin has been proposed to be the endoprotease responsible for precursor cleavage at Arg-X-Lys/Arg-Arg (RXK/RR) sites within the constitutive secretory pathway. However, there was a possibility that other protease(s) is involved in this cleavage. We here characterized furin in human colon carcinoma LoVo cells, since these cells lacked the endogenous processing activity toward RXK/RR sites and recovered the activity by transfection of furin cDNA. Furin cDNA cloned from LoVo cells had one nucleotide deletion in the region covering the homo B domain which is essential for the endoproteolytic activity. LoVo cells transfected with a furin construct with the mutation showed no activity. Based on these data, we conclude that furin is the endoprotease that is involved in the precursor cleavage at RXK/RR sites within the constitutive secretory pathway.

Amino Acid Sequence↗
PubMed1993

Effects of pituitary adenylate cyclase activating polypeptide (PACAP) on the cardiovascular system.

The effects of pituitary adenylate cyclase activating polypeptide (PACAP) on the cardiovascular system were examined. When PACAP-38 (270 or 420 pmol/kg body weight) was administered intravenously to the anesthetized dogs, both mean arterial pressure and left ventricular systolic pressure increased within 2 min after a temporal depression. Pulmonary arterial systolic pressure increased promptly. These hemodynamic values and heart rates (HR) 5 min after injection were significantly higher than the corresponding values in physiological saline injected dogs, and some effects were still sustained over 15 min. Cardiac output and stroke volume also increased and the values at 5 min were significantly higher than those in controls. The high dose of PACAP-38 (420 pmol/kg) evoked greater responses than those induced by the low dose (270 pmol/kg). Plasma adrenaline, but neither noradrenaline nor dopamine concentration significantly increased 15 min after injection of 420 pmol/kg PACAP-38. Moreover, PACAP-38 clearly stimulated cyclic AMP production in rat cardiac myocytes with EC50 of 1.5 x 10(-9) M and plasma cAMP levels significantly and dose-dependently increased in dogs 5 min after administration. These results first demonstrated that PACAP has inotropic and chronotropic actions on the heart possibly by a direct stimulation of adenylate cyclase in cardiac myocytes and also that the cardiovascular functions may be possibly modified by an evoked adrenaline secretion in vivo.

Animals↗
PubMed1993

Size-dependent chromatographic separation of nucleic acids.

Chromatographic procedures currently used for the size-dependent fractionation of nucleic acids are reviewed. First, an attempt is made to clarify the concept of "size" of nucleic acids and then various aspects of the chromatography of nucleic acids are considered. It is emphasized that consideration of the dynamic three-dimensional structure of large polynucleotides in a rapidly flowing eluent is essential for both the better understanding of mechanism and the development of sophisticated procedures. Of the practical chromatographic techniques that are not based on true size fractionation, ion-exchange chromatography on non-porous column packings appears to be the most efficient. Other methods, such as hydrophobic interaction, are unlikely to become popular. As for truly size-dependent modes, there are gel permeation and slalom chromatography. Although media with extremely large pores become available, the efficiency of gel permeation is still low as a practical separation procedure for large nucleic acid molecules. Its best use seems to be in the field of physicochemical research into nucleic acids in solution. The newly discovered slalom chromatography is based on a principle completely different from all other chromatographic modes. It enables the efficient separation of large double-stranded DNA fragments of 5-50 kilo base pairs by discriminating their length. It has proved not only to be useful as a tool for nucleic acid research but also to have great significance in other fields, e.g. the hydrodynamics of polymer solutions, the search for new chromatographic modes, etc.

Animals↗
PubMed1993

[A simple assay of peroxidase activity in cultured thyroid follicles using tetramethylbenzidine as substrate].

Thyroid peroxidase (TPO) is well known to be an essential enzyme for the biosynthesis of thyroid hormone. The changes of TPO activities in thyroid tissue have already been reported in pathophysiological and experimental conditions by several assay methods. Most of these assay methods, however, need relatively large amounts of tissue (over 10mg wet tissue) to obtain enzyme fraction for assay by homogenization and fractionation of the tissue. Therefore, it is difficult to apply these methods to relatively small numbers (less than 10(6) cells) of thyroid cells. In the present study, we attempted to develop a new and simple method for the assay of TPO activity using tetramethylbenzidine (TMB) as substrate. The reaction mixture were composed of 250 microliters of commercially available tetramethylbenzidine solution containing H2O2 (TM-Blue; TSI-CDP) and 250 microliters of cell lysate obtained by freeze-thawing in 0.1M citrate buffer (pH 4.8). Various doses of known amounts of horseradish peroxidase (HRP; 0-1000 microU) were assayed as a standard at the same time. TPO activity in cell lysate was expressed as the activity corresponding to HRP activity. In this assay method, TPO activity of sonicated-cell lysate was higher than that of nonsonicated-cell lysate, and the activity in sonicated cell lysate was linearly correlated with cell numbers. Next, the effects on the TPO activity of the direct addition of various agents into the reaction mixture were also examined. Both methylmercaptoimidazole (MMI) and NaN3 strongly inhibited TPO activity in sonicated-cell lysate as well as in mitochondria-microsomal fraction of thyroid tissue with the respective IC50 value of less than 5 microM and less than 0.1 mM. In the present method, the authors could demonstrate the following: 1) After 4 days of suspension culture with TSH (0.5 mU/ml), TPO activity of the follicles increased 3.2-5.6 fold when compared with that cultured in the absence of TSH. 2) (Bu)2cAMP (DBC; 1 mM) and forskolin (20 microM) also increased TPO activity of the follicles by 2.9-5.2 and by 2.9-6.2 fold. 3) The addition of NaI (0-100 microM) into medium dose-dependently inhibited the induction of TPO activity by TSH. 4) EGF (10(-8) M) and PMA (10(-6) M) as well as NaI (100 microM) also inhibited the induction of TPO activity in the follicles by TSH, DBC and forskolin during culture for 4 days. Accordingly, it is indicated that these agents may inhibit an induction of TPO activity at least in part at the step of post-cAMP.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

[The effect of NG-nitro-L-arginine administration on the hemodynamics and plasma hormone levels during endotoxin shock in dogs].

Although various mediators such as platelet activating factor, anaphylatoxin and cytokines are considered to be involved in the pathology of endotoxin-induced shock, an endothelium-derived relaxing factor (EDRF), nitric oxide (NO) or its related substance, has recently been shown as a vasodilating factor that is produced from L-arginine. On the other hand, NG-nitro-L-arginine (L-NNA) is shown to inhibit NO production from L-arginine. Thus, in order to examine a possible involvement of NO in the shock, the effect of L-NNA administration was studied on the hemodynamics and plasma hormone levels during endotoxin-induced shock in anesthetized dogs. Twenty-five mongrel dogs were divided into the following 5 groups; (1) In group C, only physiological saline was administered. (2) In group L, a bolus injection of L-NNA (4 mg/kg B.W.) was followed by a continuous infusion of the agent (0.05 mg/kg B.W./min) for 120 min. (3) In group E, lipopolysaccharide (LPS) E. Coli 011:B4 2.625 mg/kg body weight was administered. (4) In group LE, L-NNA administration (bolus and continuous) the same as in group L was started 5 min before the injection of LPS. (5) In group EL, L-NNA administration (bolus and continuous) was started 5 min after the injection of LPS. In Group LE, MAP decreased to -45.9 mmHg 5 min after LPS injection and -33.0 mmHg 120 min from pre-level. The levels of MAP from 15 to 90 min were significantly higher than those in Group E. In Group EL, MAP decreased to -61.4 mmHg 5 min after LPS injection and this low level (-59.5 mmHg) continued for 120 min. A protecting effect of L-NNA against LPS-induced hypotension was clearly observed only when administration of the agent was started before LPS injection. These results indicated that LPS induced shock could be produced by a possible increase of NO production in the vascular endothelial cells. The other finding in the present experiment using anesthetized animals was that L-NNA had a stimulatory action on some endocrine systems such as the renin-aldosterone system and pituitary-adrenal axis, although the exact mechanism of this action of L-NNA on such systems was unclear.

Adrenocorticotropic Hormone↗
PubMed1993

Secretion of endogenous 16-kDa beta-galactoside-binding lectin from vitamin A-pretreated chick embryonic cultured skin.

Localization of endogenous beta-galactoside-binding 16-kDa lectin and its gene expression pattern were investigated during differentiation of chick embryonic skin in vivo and in vitro and were compared with those of a 14-kDa lectin. By light microscopy, immunostaining of the 16-kDa lectin was weak in the undifferentiated epidermis, while it became intense in the keratinized epidermis, particularly in the intermediate cells. Essentially the same staining pattern was observed both in vivo and in vitro. The gene expression pattern was consistent with these immunohistochemical observations. These results were similar to those of the 14-kDa lectin [1]. On the other hand, in the vitamin A-pretreated cultured skin, mucous metaplasia of the epidermis was induced and marked changes in localization of these two isolectins were observed. The 16-kDa lectin expression was increased in the epidermis, especially in the superficial cells, and the gene expression was detected in all layers of the epidermis. However, 14-kDa lectin expression was markedly reduced in the metaplastic epidermis. In the keratinized epidermis, detailed localization of these lectins under the electron microscope was almost the same. Both of them were located primarily along the plasma membrane, in the intercellular space, and in the desmosomes. In the mucous metaplastic epidermis, however, the localization of the 16-kDa lectin was completely different from that of the 14-kDa lectin; e.g., the former was detected in the mucous granules and on the microvilli of the superficial cells, while the latter was scarcely observed in the epidermis. The present results revealed that (1) the 16-kDa lectin as well as 14-kDa lectin were expressed during the epidermal differentiation and (2) much of the 16-kDa lectin was produced and secreted from the vitamin A-pretreated cultured epidermis, while 14-kDa lectin disappeared. In the view of these facts, it is suggested that (1) both 14- and 16-kDa lectins may play an important role in differentiation of the skin and (2) the gene expression of 14- and 16-kDa lectins is regulated independently.

Animals↗
PubMed1993

Immunohistochemical and functional studies on rat high endothelial venules using monoclonal antibodies.

The distribution of high endothelial venules (HEVs) in various rat organs has been investigated immunohistochemically using two monoclonal antibodies (MoAbs), REC16-11 and REC4-1. The staining patterns observed with REC16-11 and REC4-1 were compared with those obtained with the MoAb anti-rat ICAM-1, which is a cell adhesion molecule in HEVs. REC16-11 reacted not only with HEVs but also with all vascular endothelial cells (ECs) in the tissues examined. Electronmicroscopy showed that REC16-11 and REC4-1 reacted with the cell surface antigens of ECs and immunoblot analysis of rat splenic stromal preparations showed that REC4-1 stained 42 kd and 60 kd bands. REC4-1 inhibited the binding of lymphocyte to HEVs in the mucosa-associated lymphoid tissues (MALT), but had no effects on lymphocyte binding to HEVs in peripheral (non-mucosal) lymph nodes. These findings suggested that the MoAb REC4-1 recognized the associated antigen of the lymphocyte-HEV recognition system in MALT.

Animals↗
PubMed1993

A monoclonal antibody against carbohydrate moiety of rat gastric surface epithelial cell-derived mucin.

A monoclonal antibody (MAb), designated RGM11, was generated against mucin purified from the surface epithelial layer of rat gastric mucosa. RGM11 reacted with the purified mucin which had been attached to the ELISA well. This reaction was inhibited by the oxidation of the ELISA well with periodate, indicating the carbohydrate moiety of the mucin molecule to be the epitope of RGM11. Treatment of the ELISA well with galactose oxidase also reduced the reaction with this MAb, thus suggesting the peripheral galactose and/or N-acetylgalactosamine residues of the carbohydrate moiety of mucin are involved in the epitope structure. Histochemical observation indicated that this MAb was able to stain the formalin fixed-paraffin embedded sections of rat and was positive to the surface mucous cells of corpus and antral region of the stomach and the villus epithelium of the duodenal mucosa, but other organs and tissues of rat so far examined were all negative to this MAb. These results indicate that this newly established MAb, labelled RGM11, might be useful to estimate the physiological changes in gastric surface mucous cells and the role of surface epithelial cell derived mucus in the gastric mucosal defense mechanisms.

Animals↗