PubMed Health⌕ Search

Biomedical subjects

S Hatta

Publications and source records attributed to S Hatta.

At least 19 recordsLinked to original sources
PubMed2001

Identification of two cDNAs for human actin-related proteins (Arps) that have remarkable similarity to conventional actin.

We identified two cDNAs coding for the novel human actin-related proteins (Arps) hArpM1 and hArpM2. Both of them show remarkable similarity to conventional actin, and the ATP-binding motif and nuclear-export signals of actin are highly conserved. Their mRNAs are expressed in all tested human tissues, but in smaller amounts than that of actin. These features suggest that hArpM1 and M2 are involved in cytoskeletal organization like other cytoplasmic Arp subfamilies.

Actins↗
PubMed2001

Management of posterior capsule rupture during phacoemulsification using the dry technique.

To manage posterior capsule rupture during phacoemulsification, we use a dry technique in which all procedures are performed without an irrigation/aspiration system. The dry technique is characterized by (1) continuous viscoelastic injection instead of fluid irrigation to maintain anterior chamber depth with the posterior capsule and vitreous located posteriorly and (2) static removal of most residual lens material by viscoexpression and/or manual small incision extracapsular cataract extraction without aspiration and dynamic water flow. In 16 cases of posterior capsule rupture managed using the dry technique, the residual nucleus and cortex were readily removed with minimum extension of the ruptured area and new vitreous loss. Although large amounts of viscoelastic material (mean 5.8 mL) were required, rapid and stable visual recovery was comparable to that in patients having uneventful surgery. The dry system is a safe and reliable technique for managing posterior capsule rupture during phacoemulsification.

Eye Injuries↗
PubMed2001

Experimental study using pig eyes for realizing ideal astigmatic keratotomy.

PURPOSE: The effects of varying the incision length and depth were analyzed using pig eyes to acquire information for realizing an ideal method of astigmatic keratotomy (AK). METHODS: Single and paired arcuate incisions were made on pig corneas using a diamond knife. Incisions with varying lengths of 40 degrees, 60 degrees, and 90 degrees were made with the incision depth fixed at 90% of corneal thickness. Next, paired incisions with varying incision depth from 20% to 95% of corneal thickness were made with the incision length fixed at 90 degrees. The changes in corneal shape were analyzed using corneal topography and the degrees of astigmatic change were measured using a surgical keratometer. RESULTS: For short single and paired incisions (40 degrees or 60 degrees in length), narrow areas of flattenings occurred, and steepenings were observed on both sides adjacent to the flattened areas. For long paired incisions of 90 degrees length, wide areas of flattenings and steepenings were observed with an approximately 1:1 coupling ratio, and a positive linear relationship between the incision depth and degree of astigmatic change was observed in the range of incision depth between 40% and 80% of corneal thickness. CONCLUSION: This experimental study suggests that for achieving ideal corneal sphericity after AK, long incisions covering the entire steep areas (paired 90 degrees incisions for regular astigmatism) should be used and the degree of astigmatic correction may be controlled by varying the incision depth.

Animals↗
PubMed2001

Clinical application of full-arc, depth-dependent, astigmatic keratotomy.

PURPOSE: To report a case series of the first clinical application of a new method of astigmatic keratotomy termed full-arc, depth-dependent astigmatic keratotomy (FDAK). METHODS: The type of astigmatism was analyzed by corneal topography. If the astigmatism was regular, paired arcuate incisions of 90 degrees length were used. Incision depth varied between 40% and 75% of local corneal thickness for controlling the level of astigmatic correction. RESULTS: All 13 cases had regular astigmatism, and paired arcuate incisions of 90 degrees length were used. Four cases with incisions at 40% depth, five cases at 50% depth, three cases at 60% depth, and one case at 75% depth induced vector astigmatic change of 0.93 +/- 0.33 D, 1.92 +/- 0.24 D, 3.17 +/- 0.26 D, and 4.44 D, respectively, 3 months after surgery. From 3 months to 1 year or 3 years, the postoperative astigmatism was stable, and no cases showed astigmatic regression of 0.50 D or more. Every topographic difference map indicated effective flattening and steepening occurring with a 1:1 coupling ratio. All postoperative color maps showed a marked improvement in corneal sphericity. CONCLUSIONS: In FDAK using paired 90 degrees incisions at 40-75% depth, an almost linear relationship between the incision depth and degree of astigmatic change was observed. FDAK may be an effective and safe method of astigmatic keratotomy that accurately controls the level of astigmatic correction. More clinical applications are necessary for drawing final conclusions and making a nomogram.

Aged↗
PubMed2001

Guided knives.

A new type of knife that enables a surgeon to easily create tunnel-shaped incisions with a prescribed depth has been developed. The knife features an incision guide, the arm of which extends just beyond the tip of the blade. The space between the blade and the arm can be set at the desired width. By moving the knife as if sliding the arm across the corneal or scleral surface, the blade can move to a certain depth from the surface. The guided knife enables even novice surgeons to easily make a self-sealing incision during cataract surgery. In addition, the innovative nature of this device seems to be applicable to many other surgeries that require a partial-thickness incision.

Animals↗
PubMed2000

A new concept for the correction of astigmatism: full-arc, depth-dependent astigmatic keratotomy.

OBJECTIVE: The purpose of this study is to introduce and evaluate a new concept in astigmatic keratotomy (AK) named full-arc, depth-dependent AK (FDAK). DESIGN: Noncomparative interventional case series. PARTICIPANTS: FDAK was performed on a total of 37 eyes with regular astigmatism; of these, 16 eyes received FDAK alone, and 21 eyes received FDAK combined with cataract surgery. METHODS: Corneal topography was used to divide the cornea into two discreet regions of "steep" and "flat." Then, paired arcuate incisions, 90 degrees in length, were placed along the full arc of the steep area. The level of astigmatic correction was controlled by varying the incision depth from 40% to 80% on the basis of a provisional nomogram developed by the authors. MAIN OUTCOME MEASURES: Keratometries, corneal topographies, and visual acuities were measured. RESULTS: The FDAK alone group showed a significant improvement from a preoperative corneal astigmatism of 2.90 +/- 0.78 diopters (D) to a postoperative value of 0.89 +/- 0.52 D. The "combined" group also showed significant improvement from a preoperative corneal astigmatism of 2.97 +/- 1.01 D, to a postoperative value of 1.02 +/- 0.45 D. The deviation of achieved correction from attempted correction using vector analysis was between 1.37 D of undercorrection and 0.98 D of overcorrection, with 91.9% of cases within the range of +/- 1.0 D. Slight oblique change caused by axis deviation was observed in seven cases. Both uncorrected and corrected visual acuity showed statistically significant improvement. No serious complications were encountered. CONCLUSIONS: Controlling the level of correction by varying the incision depth allowed the surgeon to use long incisions (90 degrees in length in regular astigmatism) covering the entire steep area, minimizing the undesirable changes induced by conventional deep and narrow incision AK and resulting in an ideal corneal sphericity after surgery. FDAK enabled the surgeon to accurately control the level of astigmatic correction with minimal risk of corneal perforation.

Adult↗
PubMed2000

Controlling astigmatism in cataract surgery requiring relatively large self-sealing incisions.

PURPOSE: To evaluate the results of a modified self-sealing incision for achieving astigmatic neutrality in cataract surgery requiring a 6.0 to 7.0 mm incision as well as the methods of correcting preexisting astigmatism using these incisions. SETTING: Department of Ophthalmology, Kushimoto Rehabilitation Center, Kushimoto, Japan. METHODS: To achieve astigmatic neutrality, a frown-shaped, oblique incision-the BENT (between 9 and 12 o'clock) frown-was used. To reduce preexisting against-the-rule or with-the-rule astigmatism, the incisions were placed on the temporal or superior steep astigmatic axis, respectively. A frown incision was used when aiming for mild astigmatic reduction and an arcuate incision when aiming for relatively large astigmatic reduction. RESULTS: In the 6.0 to 7.0 mm BENT frown incision group, mean flattening was minimal throughout 6 months of follow-up, with a maximum of 0.18 diopter (D) 1 week postoperatively. Surgically induced astigmatism was less than that with other incisions. Ninety-four percent of cases had a difference in absolute astigmatism of less than 0.50 D between preoperatively and 6 months postoperatively. Relatively large flattening was observed in eyes with 6.0 to 7.0 mm steep-axis incisions of superior arcuate, temporal arcuate, superior frown, and temporal frown, with means of 1.03, 0.79, 0.64, and 0.52 D, respectively, at 6 months. Ninety-eight percent of cases had a reduction in preexisting absolute astigmatism postoperatively. CONCLUSIONS: In cataract surgery using relatively large scleral self-sealing incisions, the BENT frown incision effectively achieved astigmatic neutrality. The incisions on the temporal or superior steep astigmatic axis (with selective shape) reduced astigmatism in almost all cases.

Aged↗
PubMed2000

Manual sutureless cataract surgery using a claw vectis.

Two-handed sandwich methods of extracapsular cataract extraction using a self-sealing incision have proved difficult for many inexperienced surgeons. We developed a simpler 1-handed technique using a claw vectis-a vectis with a claw placed on its tip. When the nucleus is pulled through the scleral tunnel, it is fixed by the claw and is smoothly removed from a wound of a size comparable to that in the sandwich method. During nucleus removal, viscoelastic material is constantly injected through the irrigation vectis to maintain the anterior chamber depth, resulting in a low incidence of complications. We have performed 620 cases using the technique and found it safe and easy for both novice and experienced surgeons.

Adult↗
PubMed1999

Effects of bilobalide on gamma-aminobutyric acid levels and glutamic acid decarboxylase in mouse brain.

We have previously demonstrated that bilobalide, a constituent of the Ginkgo biloba extract, possesses anticonvulsant activity, and suggested that the mechanism of its anticonvulsant action involves modulation of y-aminobutyric acid (GABA)-related neuronal transmission. This study examined the effects of bilobalide on the level of GABA and glutamate, the activity and the amount of glutamic acid decarboxylase (EC 4.1.1.15), and the function of GABA(A) receptors in the hippocampus, cerebral cortex and striatum of the mouse. GABA levels, glutamic acid decarboxylase activity, and the protein amount of 67 kDa glutamic acid decarboxylase in the hippocampus of mice treated with bilobalide (30 mg/kg, p.o., once a day for 4 days) were significantly higher than those in controls. However, there were no significant differences in glutamate levels or, the number and the dissociation constants of GABA(A) receptors in the hippocampus between control and bilobalide-treated mice. These results suggest that the anticonvulsant effect of bilobalide is due to elevation of GABA levels, possibly through potentiation of glutamic acid decarboxylase activity and enhancement of the protein amount of 67 kDa glutamic acid decarboxylase by bilobalide.

Animals↗
PubMed1999

Alterations of tubulin function caused by chronic antidepressant treatment in rat brain.

1. Antidepressants have been used clinically for many years; however, the neurochemical mechanism for their therapeutic effect has not been clarified yet. Recent reports indicate that chronic antidepressant treatment directly affects the postsynaptic membrane to increase the coupling between the stimulatory GTP-binding (G) protein, Gs, and adenylyl cyclase. Tubulin, a cytoskeletal element, is involved in the stimulatory and inhibitory regulation of adenylyl cyclase in rat cerebral cortex via direct transfer of GTP to G proteins. In this study, we investigated whether the functional change of the adenylyl cyclase system caused by chronic antidepressant treatment involves an alteration of tubulin function in the regulation of adenylyl cyclase activity. 2. Male Sprague-Dawley rats were treated once daily with amitriptyline or saline by intraperitoneal injection (10 mg/kg) for 21 days, and their cerebral cortex membranes and GppNHp-liganded tubulin (tubulin-GppNHp) were prepared for what. 3. GppNHp-stimulated adenylyl cyclase activity in cortex membranes from amitriptyline-treated rats was significantly higher than that in control membranes. Furthermore, tubulin-GppNHp prepared from amitriptyline-treated rats was more potent than that from control rats in the stimulation of adenylyl cyclase activity in the cortex membranes of the controls. However, there was no significant difference in manganese-stimulated adenylyl cyclase activity between control and amitriptyline-treated rats. 4. The present results suggest that chronic antidepressant treatment enhances not only the coupling between Gs and the catalytic subunit of adenylyl cyclase but also tubulin interaction with Gs in the cerebral cortex of the rat.

Adenylyl Cyclases↗
PubMed1999

Effect of chronic ethanol treatment of Ca2+-inhibited adenylyl cyclase in mouse striatum.

In the present study, to investigate the possibility that chronic ethanol treatment might alter Ca2+-inhibited type 5 adenylyl cyclase (AC) activity, we examined the effect of chronic ethanol treatment on striatal dopaminergic signal transduction, especially the AC system, in mice. We fed male C57BL/6 mice for 7 days with a 5% ethanol-containing or control liquid diet. Basal and forskolin-stimulated AC activities were reduced in striatal membranes of ethanol-treated mice. 5'-guanylylimidodiphosphate-stimulated AC activity was also decreased in ethanol-treated mice. But no significant differences were observed in the levels of the guanine nucleotide binding protein subunits Gs alpha and Gi1alpha&2alpha, determined by immunoblotting, between ethanol-treated and control mice. These results indicated that the function of the catalytic subunit of AC was decreased in the straitum of chronically ethanol-treated mice. We further examined the inhibitory regulation of AC activity in the context of a change of type 5 AC. Inhibition of forskolin-stimulated AC activity by 10 microM free Ca2+ was smaller in ethanol-treated mice than in control mice. However, the protein level of type 5 AC in the striatum, determined by immunoblotting, was not significantly different between ethanol-treated and control mice. These findings suggest that Ca2+-inhibited, presumably type 5, AC activity is reduced in mouse striatum by chronic ethanol treatment, and that this reduction is not due to a decrease in type 5 AC expression.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1998

Alteration in Ca2+/calmodulin-sensitive adenylyl cyclase activity in the hippocampus of stroke-prone spontaneously hypertensive rats.

This study examined the function of adenylyl cyclase (AC) activity in the hippocampus and cerebral cortex of the stroke-prone spontaneously hypertensive rat (SHRSP). Male SHRSP (8-week-old and 25-week-old) were used for the experiments, and age-matched Wistar-Kyoto rats (WKY) were used as a genetic control. Basal, forskolin-, and GppNHp-stimulated AC activities were not different between SHRSP and WKY in the 8-week-old and 25-week-old groups. Ca2+/calmodulin-sensitive AC activity in hippocampal and cerebral cortex membranes was significantly lower in 25-week-old SHRSP than in age-matched WKY, but it was not in the 8-week-old group. These results suggest that the function of Ca2+/calmodulin-sensitive, presumably type I, AC was impaired in the brain of SHRSP. Such dysfunction of AC possibly contributes to the behavioral impairment reported in passive avoidance tasks in SHRSP.

Adenylyl Cyclases↗
PubMed1998

Nasotemporal directional bias of V1 neurons in young infant monkeys.

PURPOSE: Optokinetic nystagmus (OKN) in young infants typically shows a temporal-to-nasal asymmetry under monocular viewing conditions. The neural basis for this asymmetry has been a matter of debate. One idea is that the OKN asymmetry reflects a similar asymmetry in the directional sensitivity of primary visual cortical (V1) neurons. An alternative hypothesis is that the OKN asymmetry is due to an immaturity in the ability of cortical neurons to influence the activity of subcortical structures that directly control OKN. We addressed this issue by studying the directional sensitivity of V1 neurons in young infant monkeys. METHODS: The neuronal activity of V1 units was recorded from anesthetized and paralyzed rhesus monkeys ranging in age from 6 days to 8 weeks using standard extracellular single-unit recording methods. For comparison, V1 units from normal adult monkeys were also studied. Using drifting sinusoidal gratings of the optimal spatial frequency and a moderate contrast, we measured the responsiveness of individual units to 24 directions of stimulus movement. The preferred stimulus direction and the magnitude of the directional response bias were determined by a vector summation method. RESULTS: No clear signs of nasotemporal asymmetries in direction tuning were found in our cell population from infant monkeys. However, the overall directional sensitivity and the peak monocular response amplitudes of these units were significantly lower, and binocular suppression was greater during the first 4 weeks of life than in adults. CONCLUSIONS: The OKN asymmetry in young infants may be more closely associated with the lower overall directional sensitivity and the subnormal responsiveness of V1 neurons rather than with an obvious asymmetry in the directional properties of V1 neurons.

Action Potentials↗
PubMed1997

Effects of ondansetron on electrically evoked contraction in rat stomach fundus: possible involvement of 5-HT2B receptors.

This study examined the effects of ondansetron, an antagonist of the 5-hydroxytryptamine (5-HT3) receptor without 5-HT4 receptor agonistic activity. on electrically evoked contractions and acetylcholine release in rat stomach fundus strips. Ondansetron (10(-8)-10(-4) M) produced a concentration-dependent increase in the magnitude of the electrically evoked contraction, while it inhibited the release of acetylcholine induced by electrical field stimulation. The stimulatory effect of ondansetron (10(-6) M) on electrically evoked contractions was antagonized by yohimbine, a 5-HT2B receptor antagonist, but not by SDZ 205-557 (2-methoxy-4-amino-5-chloro-benzoic acid 2-[diethylamino] ethyl ester), a 5-HT4 receptor antagonist. In the presence of tetrodotoxin, ondansetron (10(-7)-10(-5) M) enhanced the contractions induced by acetylcholine. This stimulatory effect of ondansetron on acetylcholine-induced contractions was antagonized by yohimbine. These data suggest that ondansetron potentiates the contractile response to acetylcholine in the rat stomach fundus through the activation of 5-HT2B receptors.

Acetylcholine↗
PubMed1997

Postnatal development of binocular disparity sensitivity in neurons of the primate visual cortex.

In macaque monkeys, the age at which neurons in the primary visual cortex (V1) become sensitive to interocular image disparities, a prerequisite for stereopsis, is a matter of conjecture. To resolve this fundamental issue in binocular vision development, we measured the responsiveness of individual V1 neurons in anesthetized and paralyzed infant monkeys as a function of the relative, interocular, spatial phase of dichoptic sine-wave gratings. We found that an adult-like proportion of units were sensitive to interocular image disparity as early as the sixth postnatal day, several weeks before the onset age for stereopsis in monkeys. The ocular dominance distributions of cells in infant monkeys were also indistinguishable from those of adults. Thus, at or only a few days after birth, V1 neurons are capable of combining neural signals from the two eyes as in adults and are sensitive to interocular image disparities. However, the monocular spatial-frequency response properties of these disparity-sensitive units were immature, and their overall responsiveness was far lower than that in adults. During the first 4 postnatal weeks, both the spatial frequency response properties and the peak response amplitude rapidly improved, which resulted in a corresponding increase in the absolute sensitivity of individual units to interocular disparity. The results demonstrate that early binocular vision development in monkeys is not constrained by a paucity of disparity-sensitive V1 neurons but, instead, by the relative immaturity of the spatial response properties and the overall unresponsiveness of existing disparity-sensitive neurons.

Animals↗
PubMed1997

Ca2+/CaM-sensitive adenylyl cyclase activity is decreased in the Alzheimer's brain: possible relation to type I adenylyl cyclase.

Immunoreactivities of four subtypes of adenylyl cyclase (AC) (types I, II, IV and V/VI), and basal, forskolin- and Mn(2+)-stimulated AC activities with or without calcium and calmodulin (Ca2+/CaM) were estimated in parietal cortex membranes from cases with dementia of the Alzheimer type (DAT) and age-matched controls. Immunoreactivities of AC-I and AC-II were significantly decreased, but those of AC-IV and AC-V/VI did not change in DAT brains. There was a significant correlation of AC-I immunoreactivity with Ca2+/CaM-sensitive AC activity, but not with the Ca2+/CaM-insensitive activity. Ca2+/CaM-sensitive AC activity was significantly lower in DAT than in the control, indicating that impairment of Ca2+/CaM-sensitive AC-I is clearly involved in the pathophysiology of DAT.

Adenylyl Cyclases↗
PubMed1997

Dimeric tubulin-stimulated adenylyl cyclase activity is augmented after long-term amitriptyline treatment.

We have investigated altered association of tubulin dimers interacting with G proteins and modulating adenylyl cyclase (AC) as a result of long-term amitriptyline (AMT) treatment. Gpp(NH)p-stimulated, but not basal or manganese-stimulated, AC activity was significantly augmented in cortex membranes prepared from rats chronically treated with AMT. The enhancement of AC activity by Gpp(NH)p-liganded tubulin (tubulin-Gpp(NH)p) was significantly higher in chronically AMT-treated rats than in control rats. Moreover, in cortex membranes from controls, tubulin-Gpp(NH)p prepared from chronically AMT-treated rats was more effective to activate AC activity than tubulin-Gpp(NH)p from controls. Immunoblotting and photoaffinity guanine nucleotide binding procedures showed no significant differences in the amount and the function of G proteins between controls and AMT-treated groups. It is suggested that long-term AMT treatment causes alteration in the functional interaction between tubulin and G protein, and this modification may participate in enhanced coupling of Gs to the catalytic subunit of AC induced by the chronic antidepressant treatment.

Adenylyl Cyclases↗