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Biomedical subjects

K Hirosawa

Publications and source records attributed to K Hirosawa.

At least 19 recordsLinked to original sources
PubMed1992

Immunocytochemical studies on light-induced changes in phosphatidylinositol 4,5-bisphosphate immunoreactivity in the visual system of normal and norpA mutant of Drosophila.

The distribution of phosphatidylinositol 4,5-bisphosphate (PIP2) in the visual system of Drosophila was studied by indirect immunofluorescence staining using a monoclonal antibody against PIP2. The retina of the compound eye and the cortical regions of the optic lobe were heavily stained by the antibody. In the retina, photoreceptor cells were stained with the antibody, but non-neuronal cells such as pigment cells and cone cells were not stained. The staining intensity in the light-adapted photoreceptor cells was lower than that in dark-adapted cells in normal flies, whereas no such difference in immunoreactivity was observed in the norpAEE5 mutant, whose photoreceptor cells are deficient in phospholipase C. These results suggest that the PIP2 in the photoreceptor cells is hydrolyzed by phospholipase C coded by the norpA gene upon light stimulation.

Animals↗
PubMed1991

Monoclonal antibodies which recognize endoplasmic reticulum in the retinal pigment epithelium.

Balb/c mice were immunized with dissociated chick retinal pigment epithelial cells and monoclonal antibodies prepared. Retinas of chick, bovine, rabbit, rat and mouse were examined with the monoclonal antibodies by immunofluorescence microscopy. Among the antibodies obtained, two (S5D8 and S5H8) stained the cytoplasm of epithelial cells of the animals examined in finely granular pattern and recognized a 63-kDa protein in retinal pigment epithelial cells. These antibodies, however, did not react with the rest of the chick eye (cornea, iris, ciliary body, lens and sclera) nor with extraocular tissues (liver, kidney, intestine, brain, testis, adrenal gland, heart, gizzard and skeletal muscle). Immunoelectron microscopy revealed that the antigen was localized in the endoplasmic reticulum of retinal pigment epithelial cells.

Animals↗
PubMed1991

Deep-etch visualization of the Sertoli cell (blood-testis) barrier in the boar.

The Sertoli cell (blood-testis) barrier in the boar was visualized by the freeze-fracture, deep-etch, rotary-replication technique. Three kinds of cross-bridging structures were clearly recognized in the following three ectoplasmic specialization (ES) regions; (1) cross-bridges in the intercellular space between adjacent Sertoli cell membranes; (2) cross-bridges in the space between the Sertoli cell membrane and microfilament bundles; and (3) cross-bridges in the space between microfilament bundles and subsurface cisternae. Results from immunolocalization, vinculin and alpha-actinin were recognized in the Sertoli cell barrier. Our findings show that these structural elements of the Sertoli cell barrier are held together by these cross-bridging structures, and provide important morphological evidence that implicates the ES in the dynamic function of the microfilament bundles of the Sertoli cell barrier.

Actin Cytoskeleton↗
PubMed1991

Intravenous recombinant tissue-type plasminogen activator (rt-PA) and urokinase (UK) in patients with evolving myocardial infarction--a multicenter double-blind, randomized trial in Japan.

Intravenous administrations of 2000 x 10(4)IU (33 mg) (rt-PA2) and 3000 x 10(4)IU (50 mg) (rt-PA3) of a new recombinant tissue plasminogen activator (rt-PA:TD-2061) derived from uterine endothelial cells and urokinase (UK) 96 x 10(4)IU were compared in a double blind, randomized trial of 198 patients with evolving myocardial infarction. All patients entered the trial within 6 h of the onset of symptoms and underwent baseline coronary angiography of the infarct-related coronary artery before thrombolytic therapy was instituted. Sixty minutes following thrombolytic therapy occluded infarct-related arteries were successfully reperfused in 41.5% of 66 patients in the UK, 76.4% of 72 patients in the rt-PA2, and 74.6% of 59 patients in the rt-PA3 group. Statistically significant differences were observed between the UK and rt-PA groups (p less than 0.01). Serum fibrinogen levels declined in all 3 groups at 60 min post-therapy by averages of 35.9 +/- 3.1% in the UK, 16.8 +/- 4.8% in the rt-PA2 and 17.5 +/- 4.5% in the rt-PA3 group. The difference between the UK and the rt-PA groups was statistically significant (p less than 0.01). Plasma plasminogen and alpha 2-plasmin inhibitor levels showed the same tendencies. Bleeding was the most commonly observed complication and was most commonly seen at the catheterization site. There was no difference in the incidence among the 3 groups. Hospital deaths occurred in 5.3%, 6.3%, and 4.7% of the cases in the UK, rt-PA2 and rt-PA3 groups, respectively. We conclude, therefore, that rt-PA achieves a significantly higher rate of recanalization with less extensive systemic fibrinogenolysis at the dose employed than does UK. The optimum intravenous dose of rt-PA for Japanese patients is considered to be 2000 x 10(4)IU (33 mg).

Blood Coagulation↗
PubMed1991

Immunoelectron microscopic study of the opsin distribution in the photoreceptor cells of Drosophila melanogaster.

Distribution of opsin in the compound eye of Drosophila melanogaster was examined by post-embedding immunoelectron microscopy using a monoclonal antibody against the Drosophila Rh1 opsin and gold-conjugated secondary antibody. Numerous gold particles were observed on the rhabdomeric microvilli of R1-R6 retinular cells. In the retinular cell body, gold particles were distributed in rough endoplasmic reticulum, subrhabdomeric cisternae (SRC), multivesicular bodies, and secondary lysosomes. In the rdgA mutant, whose SRC are absent, density of gold particles on the rhabdomeric microvilli was about 20% of normal. These results suggest the involvement of SRC in opsin transport.

Animals↗
PubMed1991

Three-dimensional reconstruction of goblet cells in the rabbit conjunctivum.

Goblet cells in the rabbit bulbar conjunctivum were not real "goblet," but were variable in shape. The diversity of the morphology became evident by means of computer-aided three-dimensional reconstruction. All of the cells reconstructed (N = 5) were in touch with the basal lamina, and were open to the epithelial surface. Their cytoplasm was filled with secretory granules (about 71% of the cellular volume, in average), while the nucleus occupied only 5.3%.

Animals↗
PubMed1991

[Clinical evaluation of 123I-MIBG for assessment of the sympathetic nervous system in the heart (multi-center clinical trial)].

Multi-center clinical trial of 123I-metaiodobenzylguanidine (123I-MIBG) was carried out to assess its utility as a scintigraphic imaging agent reflecting sympathetic neuronal function in cardiovascular field. Studies were performed on patients with heart diseases of three categories, myocardial infarction, angina pectoris and cardiomyopathy. Scintigraphic images, reflecting sympathetic neuronal function were obtained with 123I-MIBG from all of those categories of patients and the efficacy of the imaging was revealed in 781 (95.0%) out of 822 patients. In some patients abnormality was suggested in sympathetic neuronal function with 123I-MIBG imaging, in spite of normal findings with myocardial perfusion scintigraphy by 201TlCl. In all 981 patients studied with 123I-MIBG, there have been no severe adverse reactions, except complaints of burning on injection site of the agent or nausea, etc. from 4 patients. We conclude that 123I-MIBG imaging is one of the effective tools for diagnostic use reflecting topical sympathetic neuronal function in the heart, judging from its safety and efficacy.

3-Iodobenzylguanidine↗
PubMed1991

[Thallium-201 lung uptake in patients with chronic phase of myocardial infarction].

To study pathophysiological significance of Tl-201 lung uptake in coronary artery disease Tl-201 lung uptake was studied in 159 patients with chronic phase of myocardial infarction. Tl-201 lung uptake images were collected after rest Tl-201 myocardial imaging. Tl-201 lung uptake was estimated by comparing maximal lung counts with maximal myocardial counts (thallium lung heart ratio: LHR). Good correlation between LHR and mean pulmonary artery wedge pressure (mPw) and between LHR and left ventricular ejection fraction (EF) were obtained, (mPw = 2.7 +/- 10.5 LHR r = 0.52 n = 102, p less than 0.001, EF = 84.9-52.2 LHR r = -0.61 n = 159, p less than 0.001). It was noted that Tl-201 did not accumulate uniformly through the lung field and usually maximal Tl-201 lung uptake was noted at the basal zone of the right lung. Tl-201 lung uptake in the upper zone of the right lung increased in proportion to the hemodynamic deterioration. Interesting differences were noted between Tl-201 lung uptake in patients with chronic phase of myocardial infarction and that in patients with acute phase of myocardial infarction. The prognosis and clinical status of patients with markedly increased Tl-201 lung uptake (LHR greater than 0.8) in chronic phase were more excellent than the patients with similar Tl-201 lung uptake in acute phase. Hemodynamic parameters in patients with markedly increased Tl-201 lung uptake (LHR greater than or equal to 0.8) in chronic phase were significantly better than in those in acute phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic Disease↗
PubMed1990

Characterization of the collagen in the hexagonal lattice of Descemet's membrane: its relation to type VIII collagen.

To investigate the nature of the hexagonal lattice structure in Descemet's membrane, monoclonal antibodies were raised against a homogenate of bovine Descemet's membranes. They were screened by immunofluorescence microscopy to obtain antibodies that label Descement's membrane. Some monoclonal antibodies labeled both Descemet's membrane and fine filaments within the stroma. In electron microscopy, with immunogold labeling on a critical point dried specimen, the antibodies labeled the hexagonal lattices and long-spacing structures produced by the bovine corneal endothelial cells in culture; 6A2 antibodies labeled the nodes of the lattice and 9H3 antibodies labeled the sides of the lattice. These antibodies also labeled the hexagonal lattice of Descemet's membrane in situ in ultrathin frozen sectioning. In immunofluorescence, these antibodies stained the sclera, choroid, and optic nerve sheath and its septum. They also labeled the dura mater of the spinal cord, and the perichondrium of the tracheal cartilage. In immunoblotting, the antibodies recognized 64-kD collagenous peptides both in tissue culture and in Descemet's membrane in vivo. They also recognized 50-kD pepsin-resistant fragments from Descemet's membranes that are related to type VIII collagen. However, they did not react either in immunoblotting or in immunoprecipitation with medium of subconfluent cultures from which type VIII collagen had been obtained. The results are discussed with reference to the nature of type VIII collagen, which is currently under dispute. This lattice collagen may be a member of a novel class of long-spacing fibrils.

Amino Acids↗
PubMed1990

Increased levels of beta-human atrial natriuretic peptide-like immunoreactivity in chronically overloaded atrial tissue.

The levels and molecular form of atrial natriuretic peptide-like immunoreactivity (ANP-LI) in human atrial tissue were investigated. The levels of right atrial ANP-LI were significantly higher in mitral disease than in other cardiac or noncardiac diseases. The increased ANP-LI was mainly accounted for by an increase in beta-human ANP-LI (beta-hANP-LI). Both total ANP-LI and beta-hANP-LI levels were associated with the presence of atrial fibrillation and with increased atrial pressure. Plasma beta-hANP-LI levels were also increased in mitral disease. These results suggest that human atrium with hemodynamic overloads is characterized by increased tissue levels of ANP and by a shift to the beta-hANP form.

Adult↗
PubMed1990

Intravenous recombinant tissue-type plasminogen activator in patients with acute myocardial infarction--a report from the multicenter thrombolysis trial.

The efficacy and safety of intravenous infusion of human tissue-type plasminogen activator (rt-PA), developed in Japan (TD-2061), were investigated in 205 patients (154 men and 51 women) with evolving myocardial infarction (EMI). TD-2061 was given at a rate of 3.2 to 50 mg over 1 h after angiographic documentation of complete or subtotal (99%) occlusion. Nineteen patients were excluded as they did not meet the inclusion criteria. A total of 186 patients were divided into 6 groups according to the total dose given: Group I, 3.2 mg, 10 patients (pts); Group II, 6.4 mg, 15 pts; Group III, 12.8 mg, 15 pts; Group IV, 25.6 mg, 38 pts; Group V, 33.3 mg, 70 pts; Group VI, 50.0 mg, 38 pts. Ages ranged from 30 to 70 years (mean 60 +/- 1). Coronary angiography was done at 30 min and 1 h. In patients with TIMI grades 0 and 1, reperfusion was accomplished after 1 h in 22% of Group I, 50% of Group II, 64% of Group III, 70% of Group IV, 67% of Group V, and 74% of Group VI patients. Complications were hypotension, nausea and vomiting, bradycardia and bleeding at the puncture site. These findings suggest that clot-selective coronary thrombolysis can be induced in patients with EMI by means of human tissue-type plasminogen activator without concomitant induction of a severe systemic lytic state. The optimal dose for Japanese patients is considered to be 33.3-50.0 mg from the standpoint of reperfusion.

Adult↗
PubMed1990

Analysis of photoreceptor membrane turnover in a Drosophila visual mutant, rdgA, by electron microscope autoradiography.

A Drosophila visual mutant, rdgA, has photoreceptor cells whose rhabdomeres degenerate in several days after eclosion. Incorporations of 3H-amino acids, and 3H-mannose and 3H-glucosamine residues into the photoreceptive membranes were studied in newly emerged rdgA mutant flies by electron microscope autoradiography. The amount of 3H-amino acids incorporated in rdgA rhabdomeres at 3 hr after the injection was about 50%, and that of 3H-sugar residues was about 20% of normal. Together with our previous finding that degradative activity is low in rdgA cell bodies at this time, these data indicate that the supply of photoreceptive membrane proteins is defective in rdgA.

Amino Acids↗
PubMed1989

Structure of the subrhabdomeric cisternae in the photoreceptor cells of Drosophila melanogaster.

The structure of subrhabdomeric cisternae (SRC) and related structures in the photoreceptor cells (retinular cells) of Drosophila melanogaster in normal flies and visual mutants were compared by electron microscopic observation of semithin sections of osmium-impregnated specimens. The three-dimensional organization of SRC and the other cell organelles was demonstrated by stereoscopy. Both light- and dark-adapted normal retinular cells contained elaborate networks of anastomosing tubules of SRC immediately beneath the rhabdomeres. Tubules connecting the SRC and rough endoplasmic reticulum were frequently seen. The SRC were absent from the retinular cells of rdgAKS60 whose rhabdomeres degenerate gradually after eclosion. Instead, numerous smooth vesicles were observed in the subrhabdomeric regions. In rdgBEE170, in which rhabdomere degeneration is light dependent, the SRC appeared normal in the dark-adapted flies. But their SRC gradually disintegrated after exposure to light. In norpASB37, whose rhabdomeres are small but do not degenerate, SRC appeared normal. These results suggest that the SRC is a significant structure for the maintenance of the structure of photoreceptive membrane in the retinular cells of Drosophila.

Animals↗
PubMed1989

Morphological observations of the apical surface of chick retinal pigment epithelium.

Chick embryonic retina was examined in order to investigate morphological changes of the apical portion of retinal pigment epithelial (RPE) cells. Whole retina and RPE sheets were observed by fluorescence microscopy (rhodamine-phalloidin preparation) and transmission electron microscopy. Photoreceptor cells had no inner and outer segments on the 8th day in ovo. The inner segments have been formed on the 15th day and the outer segments on the 19th day. RPE sheets had short and blunt apical processes on the 8th day, elongated and slender ones on the 15th day, and well-developed and melanin-containing processes on the 19th day. RPE of the 19th day had numerous bundles of actin filaments associated with melanin pigments in the basal portion of the apical processes and in the apical cytoplasm. In rhodamine-phalloidin preparations, intense fluorescence was localized in the RPE apical processes and cytoplasm on the 19th day. We concluded that RPE apical processes develop in accordance with the photoreceptor development.

Actins↗
PubMed1989

Uptake of retinol by cultured fibroblasts.

Cultured fibroblasts of adult rats were used to determine whether they could take in retinol administered to the culture medium at physiological concentration. After the administration of retinol, cells were observed with a phase-contrast fluorescence light microscope (LM) and a transmission electron microscope (TEM). Retinol and retinyl fatty acyl esters (RFAE) stored in the cells were analyzed with high-performance liquid chromatography (HPLC). It was revealed that these fibroblasts could take in retinol in the medium at a concentration of 1 x 10(-7) M and store it in lipid droplets in the cytoplasm as retinyl palmitate and other RFAE.

Animals↗