Biomedical subjects

F Hayashi

Publications and source records attributed to F Hayashi.

At least 109 records · Page 6Linked to original sources

PubMed1995

Topographic analysis of the changes in corneal shape due to aging.

We studied the aging changes in corneal shape using corneal topography. Normal corneas (1,343) from 734 volunteers were examined by Topographic Modeling System-1 (TMS-1). All eyes were divided into eight groups according to age: (a) < 20 years of age and, respectively, in their (b) 20s, (c) 30s, (d) 40s, (e) 50s, (f) 60s, (g) 70s, and (h) > 80. The age-related changes in the averaged map of TMS-1 were evaluated. The findings noted in this map were confirmed by analyzing the data as well as by assessing the average-of-difference map. The averaged maps of subjects from < 20 years of age to the 40s showed a vertical bow-tie-rule astigmatism. In the maps of subjects in their 50s and 60s, the central steep area gradually extended horizontally until it became a round configuration. The maps of subjects in their 70s and > 80 revealed a horizontal oval-shaped steep area, suggesting against-the-rule astigmatism. The average-of-difference map demonstrated a marked corneal steepening at the horizontal meridians. In the data analysis of the averaged map, the mean refractive powers of the cornea increased with age. Moreover, the refractive powers in the horizontal meridians exceeded those in the vertical meridians when they were in the 60s, which verified against-the-rule astigmatic shift. In conclusion, normal cornea becomes steeper and shifts from with-the-rule to against-the-rule astigmatism with age.

Adult↗

PubMed1995

Current trends in cataract and refractive surgery in Japan--1994 survey.

A third annual survey was carried out by mail in January 1995 to investigate the current trends in cataract and refractive surgery in Japan. A questionnaire was sent to 837 ophthalmologist among members of the Japanese Society of Cataract and Refractive Surgery. Data received from 48.5% of the recipients were cross-analyzed and compared with those from the previous surveys.

Adult↗

PubMed1994

Light-dependent in vivo phosphorylation of an inhibitory subunit of cGMP-phosphodiesterase in frog rod photoreceptor outer segments.

In vivo phosphorylation of P gamma, an inhibitory subunit of cGMP-phosphodiesterase of frog (Rana catesbeiana) photoreceptor rod outer segments, was investigated using a quick-freezing technique and a newly developed method for the preparation of rod outer segments. Light-dependent phosphorylation of P gamma was observed. Okadaic acid, a potent inhibitor of protein phosphatases 1 and 2A, enhanced the apparent incorporation of 32P into P gamma, suggesting that P gamma is in equilibrium between phosphorylation and dephosphorylation. Neither phorbol ester, a potent activator of protein kinase C, nor changes in the extracellular Ca2+ concentration affected the in vivo phosphorylation of P gamma.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1994

Ultrastructural localization of retinal guanylate cyclase in human and monkey retinas.

Immuno-imaging with confocal and electron microscopy revealed the localization of retinal guanylate cyclase (RetGC) in human and monkey retinas. Using an antibody against a peptide derived from human RetGC, RetGC was found predominantly in the photoreceptor layer in these retinas, although a small amount of RetGC was detected in various other retinal cells. In particular, the cone outer segments were more densely labeled with the antibody than the rod outer segments. The RetGC in outer segments was localized exclusively in the membrane-rich domains, and appeared to be associated with the marginal region of the disk membrane and/or the plasma membrane. The connecting cilium and its cytoplasmic extension never showed immunoreactivity with the antibody. The localization of RetGC in photoreceptor cells is discussed from the viewpoint of mechanisms for the recovery of photoreceptors to the dark level.

Animals↗

PubMed1994

Phosrestin I undergoes the earliest light-induced phosphorylation by a calcium/calmodulin-dependent protein kinase in Drosophila photoreceptors.

Activation of PI-PLC initiates two independent branches of protein phosphorylation cascades catalyzed by either PKC or Ca2+/calmodulin-dependent protein kinase (CaMK). We find that phosrestin I (PRI), a Drosophila homolog of vertebrate photoreceptor arrestin, undergoes light-induced phosphorylation on a subsecond time scale which is faster than that of any other protein in vivo. We determine that a CaMK activity is responsible for in vitro PRI phosphorylation at Ser366 in the C-terminal tryptic segment, MetLysSer(P)IleGluGlnHisArg, in which Ser(P) represents phosphoserine366. We also demonstrate that Ser366 is the phosphorylation site of PRI in vivo by identifying the molecular species resulting from in-gel tryptic digestion of purified phospho-PRI using HPLC-electrospray ionization tandem quadrupole mass spectroscopy. From these data, we conclude that the CaMK pathway, not the PKC pathway, is responsible for the earliest protein phosphorylation event following activation of PI-PLC in living Drosophila photoreceptors.

Amino Acid Sequence↗

PubMed1994

Corneal endothelial cell loss after phacoemulsification using nuclear cracking procedures.

This study assessed corneal endothelial damage in endocapsular phacoemulsification surgery using a nuclear cracking procedure in which the nucleus was divided into four quadrants and emulsified. Forty-five eyes had phacoemulsification using this technique, and 33 eyes had phacoemulsification using undivided sculpting techniques (without cracking). We examined the extent of endothelial cell loss at one and three months after surgery using specular microscopy. We also measured ultrasound time, time spent for phacoemulsification, and infusion volume during surgery. Endothelial cell loss was significantly less in the nuclear cracking group than in the undivided sculpting group. Ultrasound time in surgery with cracking was significantly shorter than that in surgery without cracking. The time for the phacoemulsification maneuvers and the infusion volume were the same for both procedures. These findings indicate that the ultrasound time was shortened using the nuclear cracking technique and resulted in less corneal injury.

Aged↗

PubMed1994

Corneal topographic analysis of superolateral incision cataract surgery.

Using corneal topography, we compared the corneal shape changes following superolateral incision cataract surgery with those following conventional superior incision surgery. In our superolateral incision procedure, a 6.5 mm limbal incision was made from the 9 o'clock to 11 o'clock meridians to avoid incising the superior limbus. One hundred four patients were divided into two groups; Group 1 comprised 66 patients who had surgery using the superolateral approach; Group 2 comprised 38 patients who had surgery using the superior approach. The corneas were examined by keratometer and topographic modeling system preoperatively, and at one week and one, three, and six months postoperatively. Keratometric measurements showed that surgically induced astigmatism (SIA) in Group 1 was significantly less than that in Group 2 throughout the six-month observation. The standard SIA deviation in Group 1 was also smaller than that in Group 2, indicating a smaller degree of variability in the superolateral incision surgery. In the corneal topographic analysis, a color-coded map averaging all the Group 1 corneas at each interval showed a slight steepening in the central cornea in the 10 o'clock meridian one week after surgery. This surgically induced steepening disappeared by one month, and the corneal shape recovered its preoperative shape. In contrast, the Group 2 averaged map showed a marked steepening of the upper and lower corneas. The steepening gradually decreased but remained until three months after surgery. Superolateral incision surgery induced a smaller degree of change in the corneal shape, as well as in SIA, than superior incision surgery. The postoperative corneal shape changes disappeared rapidly after the superolateral incision, and the corneal shape soon stabilized and recovered its preoperative shape.

Aged↗

PubMed1994

Complications associated with endocapsular balloon implantation in rabbit eyes.

After phacoemulsifying the lens in six rabbit eyes through a 1.3 mm anterior capsule opening, we implanted a silicone balloon in the capsular bag and filled it with liquid silicone. The eyes were enucleated nine to 21 months postoperatively, embedded in paraffin, stained with toluidine blue, and examined by stereoscopic and light microscopy. We looked at the postoperative complications primarily. All balloons were securely fixated within the capsule. Surface wrinkles were observed in two balloons. The injected silicone remained transparent. None of the lens capsules was completely transparent, although all remained relatively clear. Retrocorneal membranes were produced in one eye in which the silicone leaked.

Accommodation, Ocular↗

PubMed1994

Characteristics of the hepatocarcinogenesis caused by dehydroepiandrosterone, a peroxisome proliferator, in male F-344 rats.

The characteristics of the hepatocarcinogenesis induced by dehydroepiandrosterone (DHEA) were compared with that induced by other peroxisome proliferators such as [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid (Wy-14,643) and di(2-ethylhexyl)phthalate (DEHP). Male F-344 rats were given a diet containing DHEA at 0.5 or 1%, Wy-14,643 at 0.1% and DEHP at 2% for up to 78 weeks. In rats fed 0.5 or 1% DHEA the incidence of neoplasias was 20% after 52 weeks. At 78 weeks all rats treated with 1% DHEA had numerous grossly visible nodules and the incidence of hepatic neoplasia was dose-dependent. The magnitude of hepatocellular tumorigenicity after DHEA treatment was less potent than that after Wy-14,643, but more than that after DEHP treatment. Peroxisomal beta-oxidation activity increased three- or six-fold after a 10 week course of 0.5 or 1% DHEA respectively and this was significantly lower than that induced in Wy-14,643- or DEHP-fed rats. From 52 to 78 weeks these activities increased 3-9 times over that in controls. In both the group of rats treated with Wy-14,643 and those treated with DEHP, peroxisomal beta-oxidation constantly increased 11- to 15-fold during the experiment. Catalase activity increased 1.3- to 1.5-fold for the first 10 weeks of DHEA treatment and then recovered to the control level. The activities of glutathione peroxidase and glutathione S-transferase decreased markedly after 30 weeks in DHEA-treated rats and the decreases were sustained for up to 78 weeks. The profile of changes in enzyme activities in the rats fed DHEA was not significantly different from that of those fed Wy-14,643 or DEHP. There were no increases in 8-hydroxydeoxyguanosine, oxidative DNA damage or lipid peroxide level in the liver in any of the treated rats at 10 or 30 weeks. Since these results showed that the characteristics of hepatocarcinogenesis caused by DHEA were basically similar to those caused by Wy-14,643 and DEHP, typical peroxisome proliferators, hepatocarcinogenesis induced by DHEA is probably due to the same mechanisms as that induced by general peroxisome proliferators.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1994

Corneal endothelial cell loss following phacoemulsification using the Small-Port Phaco.

We studied the extent of corneal endothelial injury after phacoemulsification using the Small-Port Phaco (SPP), a new phacoemulsification instrument that allows linear aspiration during phacoemulsification. Of 72 eyes undergoing phacoemulsification, the SPP was used in 33 (group 1) and a standard phacoemulsification instrument in 39 (group 2). Endothelial cell density was examined by specular microscopy preoperatively and at 1 and 3 months after surgery, and the percentage of endothelial cell loss was evaluated. Operative factors influencing endothelial injury such as the duration of ultrasound emission, the ultrasound power expended, and the amount of irrigating solution used also were measured. The percentages of endothelial cell loss at both 1 and 3 months were significantly less (P < .05) in group 1 than in group 2 (in group 1, 4.3 +/- 3.4% at 1 month, and 5.6 +/- 3.8% at 3 months; in group 2, 6.9 +/- 4.6%, and 8.3 +/- 5.4%, respectively). The duration of emission was shorter and the ultrasound power discharged was smaller in the SPP cases. Since the total ultrasound energy emitted in the SPP cases was less than that in the standard-instrument cases, we conclude that the reduced corneal endothelial damage observed in group 1 was directly related to the smaller total ultrasound power expended in these cases.

Aged↗

PubMed1993

Secondary structure of the oct-3 POU homeodomain as determined by 1H-15N NMR spectroscopy.

Most of the 1H and 15N magnetic resonances of the 66 amino acid long POU homeodomain of mouse Oct-3 have been assigned by the combined use of the two-dimensional homonuclear, and two- and three-dimensional heteronuclear NMR methods. The sequential NOE connectivities and amide proton exchange measurements indicate the presence of three helical regions within the domain. The positions of the three helices correspond well to those of other homeodomains, the three-dimensional structures of which have already been determined. The present NMR study provides the first experimental evidence for the existence of a helix-turn-helix motif in the oct-3 POU homeodomain.

Amino Acid Sequence↗

PubMed1993

Regulation of G protein function by an effector in GTP-dependent signal transduction. An inhibitory subunit of cGMP phosphodiesterase inhibits GTP hydrolysis by transducin in vertebrate rod photoreceptors.

The regulation of cGMP phosphodiesterase in vertebrate rod photoreceptors is a typical G protein-dependent signal transduction mechanism. The interaction of P gamma, an inhibitory subunit of cGMP phosphodiesterase, with transducin alpha subunit (T alpha) is essential for the activation of cGMP phosphodiesterase. It has been shown that, in a homogenized preparation of frog (Rana catesbeiana) rods, P gamma interacts with GTP.T alpha and remains tightly bound to GDP.T alpha after GTP hydrolysis on T alpha. Association of this complex with beta gamma subunits of transducin (T beta gamma) triggers the release of P gamma from the complex and the subsequent inactivation of cGMP phosphodiesterase. In a system reconstituted with purified components, both GTP- and GDP-bound forms of T alpha were found to interact with P gamma. Under these conditions, P gamma inhibited GTP hydrolysis by transducin in a noncompetitive manner with a Ki of 92 nM. Binding of an hydrolysis-resistant GTP analog to T alpha was also inhibited by P gamma. These inhibitions of transducin function were resulted from the inhibition of both hydrolysis of GTP bound to T alpha and interaction of GDP.T alpha with membrane-bound T beta gamma. However, after GDP.T alpha reassociated with membrane-bound T beta gamma, the inhibitory effect of P gamma on the binding of an hydrolysis-resistant GTP analog to T alpha was greatly diminished, suggesting that the GTP/GDP exchange on T alpha was not inhibited by P gamma. These data indicate that the T alpha function is altered during complexing with P gamma. G protein functions may be modified by interacting with an effector in the G protein-dependent signal transduction.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1993

Topographic analysis of early changes in corneal astigmatism after cataract surgery.

Using the Topographic Modeling System (TMS), we studied the early changes in anterior corneal curvature following cataract surgery. Thirty patients who had planned extracapsular cataract extraction (p-ECCE) or phacoemulsification were evaluated with TMS at three days, and one, two, three, and five weeks postoperatively. After p-ECCE, the upper part of the cornea which corresponded to the wound and the lower cornea markedly steepened and showed a bow-tie pattern of astigmatism. Eight (57%) of 14 cases showed little reduction in the corneal steepening at five weeks postoperatively. In five cases (36%) the steepening in the lower cornea was less than the minimal change in the upper cornea. After phacoemulsification, corneal steepening was much less than it was after p-ECCE; three cases (17%) showed almost no surgically induced alteration of the cornea. In eight phacoemulsification cases (61%), postoperative corneal steepening decreased rapidly and the corneal shape recovered within five weeks. Our topographic analysis clearly demonstrated that a smaller wound in phacoemulsification surgery produced less corneal steepening and stabilized more rapidly than a larger wound in p-ECCE.

Aged↗

PubMed1993

Changes in corneal shape after suture cutting using the argon laser for postoperative astigmatism following cataract extraction.

We studied the changes in corneal shape after suture cutting with an argon laser to reduce corneal astigmatism following cataract extraction. Sixty-two patients who exhibited high with-the-rule astigmatism (> 3 diopters [D]) following extracapsular lens extraction had argon laser suture cutting. The patients were classified into three groups: Group A comprised 30 patients whose sutures were cut two to three months after planned extracapsular cataract extraction (p-ECCE); Group B consisted of eight patients who had the same treatment five to nine months after p-ECCE; Group C comprised 24 patients who had the treatment one to two months after phacoemulsification (PE). The dioptric reduction of corneal astigmatism (the percent reduction of astigmatism) was 1.83 +/- 0.98 D (37.4 +/- 18.3%) in Group A, 3.20 +/- 2.35 D (55.6 +/- 34.4%) in Group B, and 2.08 +/- 1.20 D (41.4 +/- 20.4%) in Group C. There was no statistical significance in the dioptric reduction and the percent reduction among Groups A, B, and C. This suggests that the wound size and time of cutting are not directly correlated to the effect of argon laser suture cutting. To examine the relationship between the effect and changes in corneal shape from suture cutting, we divided the patients into two subgroups; one was Subgroup (+) in which the percent reduction of astigmatism was above 25%; the other was Subgroup (-) in which the percent reduction was below 25%.(ABSTRACT TRUNCATED AT 250 WORDS)

Astigmatism↗

PubMed1993

Cytokine production by peripheral blood monocytes/macrophages in multiple sclerosis patients.

To determine the function of monocytes/macrophages in the acute phase of multiple sclerosis (MS), we investigated the production of tumor necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha), IL-1 beta and IL-6 by peripheral blood monocytes/macrophages (PBM) in patients with MS, other autoimmune neurological disease (OAND), other neurological disease (OND) and normal controls was assessed using enzyme-linked immunosorbent assay (ELISA). When stimulated with lipopolysaccharide or phorbol ester, PBM obtained during acute phase of MS relapse patients produced significantly higher amounts of all these cytokines than did PBM from patients with chronic stable MS or OAND or OND or from normal controls. The results suggest a possible role of activated monocytes/macrophages in the acute exacerbation of MS.

Adult↗

PubMed1993

Time-dependent phrenic nerve responses to carotid afferent activation: intact vs. decerebellate rats.

The objectives were to determine 1) respiratory responses to carotid chemoreceptor inputs in anesthetized rats and 2) whether the cerebellar vermis plays a role in these responses. A carotid sinus nerve was stimulated (20 Hz) with five 2-min trains, each separated by approximately 3 min. During stimulation, respiratory frequency (f), peak amplitude of integrated phrenic nerve activity (integral of Phr), and their product (f x integral of Phr) immediately increased. As stimulation continued, integral of Phr progressively increased to a plateau [short-term potentiation (STP)], but f and f x integral of Phr decreased [short-term depression (STD)] to a value still above control. Upon stimulus termination, integral of Phr progressively decreased but remained above control; f and f x integral of Phr transiently decreased below baseline. After the final stimulation, integral of Phr remained above control for at least 30 min [long-term facilitation (LTF)]. Repeated 5-min episodes of isocapnic hypoxia also elicited STP, STD, and LTF. Vermalectomy lowered the CO2-apneic threshold and eliminated LTF. In conclusion, carotid chemoreceptor activation in rats elicits STP and LTF similar to that in cats; the vermis may play a role in LTF. A new response, STD, was observed.

Afferent Pathways↗

PubMed1993

Current trends in cataract and refractive surgery in Japan--1992 survey.

A survey was carried out by mail in January 1993 to investigate the current trends in cataract and refractive surgery in Japan. A questionnaire was sent to members of the Japanese Intraocular Lens Implant Society, and replies were received from 59.2% prior to the cut-off date of February 15. Results were cross-analyzed and compared with the data from American and British surveys.

Adult↗

PubMed1993

[Changes in corneal astigmatism with aging].

Change in physiologic corneal astigmatism due to aging was studied. A series of 868 cases (1,660 eyes) was evaluated. These eyes were divided into 6 groups by age; A) below 40 years, B) in the 40's, C) in the 50's, D) in the 60's, E) in the 70's, and F) over 80. Corneal astigmatism was examined with an autokeratometer. In Group A, 88.5% had with-the-rule astigmatism (WTR), whereas only 3.7% had against-the-rule astigmatism (ATR). The cylindrical diopter (CD) of WTR was 1.29 +/- 0.73 D, which was significantly the largest among the groups. In Group C, WTR decreased to 55.9% and ATR increased to 22.9%. The CD of WTR also decreased to 0.85 +/- 0.47 D. In Group E, WTR was 31.4% and ATR was 49.3%. The CD of ATR increased to 0.88 +/- 0.70 D. In Group F, WTR was 19.9%, whereas ATR was 65.9%. The CD of ATR was 1.48 +/- 0.88 D, which was the largest among the groups. As such, WTR was dominant at younger ages, and ATR increased with aging at older ages. The CD of WTR decreased, and ATR increased, with aging.

Adult↗