Biomedical subjects

H Aonuma

Publications and source records attributed to H Aonuma.

18 recordsLinked to original sources

PubMed1999

GABAergic and non-GABAergic spiking interneurons of local and intersegmental groups in the crayfish terminal abdominal ganglion.

In the first step toward identifying the neurotransmitter released from spiking interneurons of both local and intersegmental groups in the crayfish terminal abdominal ganglion, the authors examined whether spiking local interneurons and ascending intersegmental interneurons contain the transmitter gamma-aminobutyric acid (GABA). In this paper, 17 identified ascending interneurons and three spiking local interneurons were stained by intracellular injection of Lucifer yellow and subsequently treated for immunocytochemical staining against GABA. Double-labeling experiments revealed that six identified ascending interneurons are GABAergic, but no spiking local interneurons show GABA-like immunoreactivity. Four ascending interneurons with GABA-like immunoreactivity (reciprocal closing ascending neuron 5 [RC-5], reciprocal opening ascending neuron 6 [RO-6], variable-effect ascending interneuron 1 [VE-1], and no-effect ascending interneuron 4[NE-4]) had cell bodies that formed a cluster on the ventral surface of the rostral edge of the ganglion, whereas two GABAergic interneurons (coinhibiting ascending interneuron 2 [CI-2] and NE-2) had cell bodies in a caudal region around the cell body of the seventh flexor inhibitor (FI) motor neuron. Another four rostral interneurons (RC-2, RC-3, RC-4, and NE-3) and seven caudal interneurons (CI-3, RC-7, RO-1, RO-2, RO-3, RO-4, and NE-1) had no GABA-like immunoreactivity. Because VE-1 is known to make direct inhibitory connections with other ascending interneurons, whereas RC-3 and RO-1 are known to make direct excitatory connections, the immunocytochemical results from this study are consistent with previous physiological studies. Although many spiking local interneurons (including spiking local interneuron 1 of the anterior group [sp-ant1]) made direct inhibitory connections with nonspiking local interneurons, three spiking local interneurons (sp-ant1, spiking local interneuron 6 of the medial group [sp-med6], and spiking interneuron 5 of the posterior group [sp-post]) do not show GABA-like immunoreactivity. These results suggest that the inhibitory transmitter released from spiking local interneurons is not GABA but that another substance mediates the inhibitory action of these interneurons. J. Comp. Neurol. 410:677-688.

Action Potentials↗

PubMed1999

Processing of proprioceptive signals by ascending interneurones in the terminal abdominal ganglion of the crayfish.

Intersegmental interneurones are crucial for the appropriate coordination of the activity of local circuits located in different body segments. We have analysed the synaptic inputs to ascending intersegmental interneurones from a proprioceptor in the tailfan of the crayfish. Twenty identified interneurones responded during stimulation of the exopodite-endopodite chordotonal organ. Of these 20 interneurones, three were excited phaso-tonically, nine were excited phasically and eight were inhibited. All received convergent exteroceptive inputs from water-motion- or touch-sensitive hairs on the uropods. The effects of simultaneous exteroceptive and proprioceptive stimulation depended upon the identity of an interneurone. For interneurones that were inhibited by proprioceptive stimulation, suprathreshold exteroceptive responses were reduced to a subthreshold level by simultaneous proprioceptive stimulation. In contrast, for interneurones that were excited by proprioceptive stimulation, the simultaneous application of subthreshold proprioceptive and exteroceptive stimulation elicited action potentials. Two of the interneurones that receive proprioceptive input (NE-1 and RC-8) are known to be presynaptic to giant interneurones that mediate and coordinate the tail-flip. Many of the other interneurones that receive proprioceptive inputs in the tailfan are known to excite abdominal extensor motor neurones. Thus, proprioceptive input to these intersegmental interneurones could serve two roles: first, to extend the abdomen during postural movements or prior to escape and, second, to drive the tail-flip escape response.

Journal Article↗

PubMed1997

Distribution of GABAergic premotor nonspiking local interneurones in the terminal abdominal ganglion of the crayfish.

The inhibitory neurotransmitter of premotor nonspiking local interneurones in the crayfish terminal abdominal ganglion was investigated physiologically and immunocytochemically. Depolarization of a nonspiking interneurone evoked a hyperpolarization in a uropod motor neurone. The amplitude of hyperpolarization in the motor neurone was gradually decreased under low-calcium/high-magnesium saline. Local pressure injection of gamma-aminobutyric acid (GABA) into the neuropil caused a similar hyperpolarization of the motor neurone. These physiological studies suggested a GABAergic inhibitory interaction between nonspiking interneurones and the motor neurones. Premotor nonspiking interneurones are classified into two subgroups ofposterolateral (PL) and anterolateral (AL) interneurones, and AL interneurones are further divided into three subtypes. A combination of intracellular staining from nonspiking local interneurones with Lucifer yellow and immunocytochemical staining with an antiserum directed against GABA revealed that all the PL interneurones sampled in this study showed GABA-like immunoreactivity. A population of cell bodies (n = 6-11) with a small diameter (15-30 microm) packed together forming a cluster showed GABA-like immunoreactivity, and the cell bodies of most PL interneurones were found in this cluster. To compare the number and the pattern of main branches of PL interneurones, cells were classified into three identifiable sets of interneurones, called PL-1, PL-2, and PL-3. By contrast, about one-half of AL interneurones, especially the third subtype of AL interneurones, which have cell bodies located ventrolaterally in the ganglion, did not show GABA-like immunoreactivity. Furthermore, the position of cell bodies of GABA-immunoreactive AL interneurones was scattered compared to that of PL interneurones.

Abdomen↗

PubMed1997

Convergent chemical and electrical synaptic inputs from proprioceptive afferents onto an identified intersegmental interneuron in the crayfish.

Synaptic transmission between proprioceptive afferents from a chordotonal organ in the tailfan of the crayfish and an identified ascending interneuron, interneuron A, in the terminal abdominal ganglion was analyzed. Interneuron A is part of a disynaptic pathway from primary afferent neurons to the lateral giant interneuron involved in producing the characteristic ballistic escape behavior of crayfish. Interneuron A received short and long latency excitatory postsynaptic potentials (EPSPs) from chordotonal afferents. Short latency EPSPs occurred with little central synaptic delay, were unchanged by hyperpolarizing current injection of -2 nA, and remained at a constant amplitude when the nervous system was bathed in saline with a low calcium concentration or saline containing the nicotinic antagonist curare. These EPSPs are thus thought to be mediated by electrical transmission. Longer latency potentials were increased in amplitude by hyperpolarizing current injection, reduced in amplitude when the nervous system was bathed in low-calcium saline, and also reduced by bath application of saline containing curare. These potentials are thus thought to be mediated by chemical transmission. The functional significance of the dual modes of transmission at a key synapse in the escape circuitry is discussed.

Afferent Pathways↗

PubMed1996

Presynaptic inhibition of exteroceptive afferents by proprioceptive afferents in the terminal abdominal ganglion of the crayfish.

1. Exteroceptive hairs that are sensitive to water displacement and touch are distributed over the surface of the tailfan of crayfish. We show that the sensory neurons innervating these hairs receive a primary afferent depolarization (PAD) from sensory neurons innervating a proprioceptor that monitors movements of the endopodite and protopodite of the tailfan. This PAD occurs only during high-velocity movements of the exopodite, which are similar to those that occur during swimming. The effects that the proprioceptor mediate are widespread, so that afferents in four sensory nerve roots of the terminal abdominal ganglion, innervating hairs on the protopodite, exopodite, endopodite, and telson, receive a PAD. The PAD is unlikely to be mediated through monosynaptic pathways because there is no anatomic overlap between the central projections of chordotonal afferents and many of the exteroceptive afferents. The depolarization is associated with a conductance increase and can be increased by the injection of hyperpolarizing current or reversed (approximately 10 mV above resting potential) by injection of depolarizing current. The properties of the presynaptic input are, therefore, consistent with being mediated through chemical synapses. This is supported by the observation in the electron microscope that the exteroceptive afferents receive chemical input synapses. The depolarization is mimicked by gamma-aminobutyric acid and reduced by bath application of picrotoxin or bicuculline, suggesting that it is a depolarizing inhibitory postsynaptic potential. The PAD reduces the amplitude of exteroceptive afferent spikes, an action that is thus likely to reduce transmitter release and the efficacy of synaptic transmission.

Action Potentials↗

PubMed1996

GABA-like immunoreactivity of an identified nonspiking local interneurone in the crayfish terminal abdominal ganglion

Using an antiserum directed against -aminobutyric acid (GABA) to label neurones with GABA-like immunoreactivity, approximately 70 central neurones (68±9; mean ± s.e.m., N=9) were labelled in the terminal abdominal ganglion of the crayfish Procambarus clarkii. This mean number of neurones with GABA-like immunoreactivity represents approximately 10 % of the total number of neurones in the terminal ganglion. A combination of intracellular staining using Lucifer Yellow and immunocytochemical staining revealed that an identified nonspiking local interneurone (the local directionally selective interneurone, LDS) showed GABA-like immunoreactivity.

Journal Article↗

PubMed1995

Colonic and peritoneal tuberculosis associated with coloduodenal fistula.

We report a very rare case of tuberculous colitis that showed relatively long-segment involvement of the colon near the hepatic flexure with coloduodenal fistula that caused severe malnutrition. The formation of fistula in abdominal tuberculosis is very rare. This is the eighth reported case of abdominal tuberculosis with fistula and the first reported case with a coloduodenal fistula.

Adult↗

PubMed1995

Late onset hepatic failure due to hepatitis B virus with mutations in the pre-core region.

A 60-year-old man complained of severe general fatigue on October 11, 1992. Pertinent laboratory findings were: aspantate aminotransferase (AST) 1920 IU, alanine aminotransferase (ALT) 2050 IU, and total bilirubin (T. Bil) 124 micromol/l (normal range, 0-17 micromol/l). Virological assay revealed that hepatitis B surface antigen (HBsAg), anti-hepatitis B e (HBe), anti-HBc, and immunoglobulin M (IgM) anti-HBc were positive, and anti-HBs, HBeAg, and anti-delta antibody were negative. A diagnosis of acute hepatitis due to hepatitis B virus was made. Despite a decrease in transaminase, jaundice worsened and prothrombin time was prolonged. On the 60th day of hospitalization, massive ascites developed, but the patient's consciousness was not impaired. Although, albumin and diuretics were given, the ascites further increased. Paracentesis of 2000 ml of ascitic fluid was performed twice a week. On the 120th day of hospitalization, the patient passed black stools and he exhibited renal failure 3 weeks later. Although severe jaundice persisted, he was still alert. On the 150th day of hospitalization, massive gastrointestinal bleeding occurred, due to hemorrhagic gastritis. Despite receiving intensive care, the patient died. Determination of the HBV DNA sequence revealed two point mutations in the pre-core region; these have not been reported elsewhere.

DNA, Viral↗

PubMed1995

A chorioretinal lesion in a patient with Kimura's disease.

A 47-year-old male patient with Kimura's disease showed a white and slightly elevated choroidal lesion surrounded by serous retinal detachment in his left eye. Serological examination revealed esinophilia. Swelling in his left cheek had been increasing during a period of 20 years, and diagnosis of Kimura's disease had been made earlier by biopsy. Fluorescein angiography suggested disturbance of choroidal circulation and dysfunction of retinal pigment epithelium. After corticosteroid therapy, improvement was seen in the fundus findings, the swelling in the cheek and eosinophilia.

Angiolymphoid Hyperplasia with Eosinophilia↗

PubMed1994

Morphological and physiological bases of crayfish local circuit neurones.

As the subject of neuroethological studies, arthropods offer several advantages to elucidate the neural processes that generate and control behavioural acts. The relative simplicity of their neural organization and their identifiable neurones are particularly advantageous. The crayfish, Procambarus clarkii, uropods are paired appendages of the last abdominal segment that show bilateral closing movement in response to mechanical stimulation. This movement, the avoidance "dart" response, is mediated by a cascade and parallel organization of local circuit neurones in the terminal abdominal ganglion. Thirty intersegmental ascending interneurones and 20 spiking local interneurones have been identified both morphologically and physiologically. They receive exteroceptive inputs directly from the sensory afferents. Two complementary groups of unilateral nonspiking local interneurones have also been functionally identified. They exert fine control over the wide range of activity of motor neurones in a graded and sustained manner. These nonspiking interneurones form opposing and parallel pathways that are essential in modulating the pattern of movement of the uropods.

Animals↗

PubMed1993

Liver sarcoidosis showing low-density intrahepatic septa on postcontrast computed tomography.

The authors present a patient with massive liver sarcoidosis, showing only slight hepatomegaly on precontrast computed tomogram and multiple low-density intrahepatic septa on postcontrast computed tomogram. Sarcoidosis frequently involves the liver, but rarely shows abnormal findings other than hepatomegaly on computed tomograms. Only a few cases have demonstrated a low density intrahepatic area on computed tomograms. In this report, we present a patient with massive liver and pulmonary sarcoidosis, showing low density intrahepatic septa and pulmonary fibrosis on computed tomograms.

Humans↗

PubMed1992

Gastric emptying after pancreatoduodenectomy with total stomach preservation and selective proximal vagotomy.

This study evaluates postoperative gastric emptying following a new method of pancreatoduodenectomy with total stomach preservation and selective proximal vagotomy performed on 10 patients with diseases affecting the head of the pancreas, 7 being malignant and 3 benign. Reconstruction was carried out using the Billroth I and Billroth II techniques in 5 patients each, respectively. Early postoperative gastric emptying was evaluated by the time before intragastric tube removal and the resumption of oral intake, as well as by barium gastric radiography, while late postoperative gastric emptying was evaluated by the acetaminophen method. No difference was seen in early postoperative gastric emptying between the two surgical techniques, the mean time which elapsed before intragastric tube removal being 4.4 days for the Billroth I and 4.5 days for the Billroth II patients, and the mean time until the resumption of oral intake being 6.8 days for the Billroth I and 7.0 days for the Billroth II patients. A significant delay in gastric emptying was seen in the Billroth II patients compared to a normal control group, 30 and 45 min after acetaminophen administration, but the difference in gastric emptying between the Billroth I and II patients was not significant. Moreover, both techniques impaired gastric emptying much less than Traverso's pylorus-preserving pancreatoduodenectomy.

Aged↗

PubMed1990

[Cavum vergae, cyst of cavum septi pellucidi, mega cisterna magna, and general fibrosis syndrome].

One family of 17 cases of general fibrosis syndrome was reported. Four out of five patients examined with CT and/or MRI revealed cavum vergae or cyst of the cavum septi pellucidi or mega cisterna magna, which were characterized by existing on the midline of the brain. The patient with cavum vergae had also platybasia. In one patient, surgical correction of vertical deviation and blepharoptosis of both eyes was performed. There was abnormal insertion of the superior and inferior rectus muscles in posterior and nasal direction, and adhesion of the superior oblique muscle to the superior rectus muscle at the point of it's insertion was found in both eyes. Histopathological findings of the extraocular muscles of two patients showed mixture of relatively normal muscle tissues and vast amounts of collagen fibers. Electron microscopically many glycogen granules were found in muscle fibers. From these findings, this syndrome may be based on failure in development and differentiation.

Adult↗

PubMed1987

Possible pathogenesis of congenital stationary night blindness.

We reported a case of congenital stationary night blindness (CSNB) who showed Schubert-Bornschein type electroretinogram (ERG) in the right eye and nearly normal ERG in the left eye with absolute glaucoma. From the electrophysiological findings of both eyes and histological findings of the enucleated eye, we concluded that the mechanism of night blindness in CSNB is an abnormal inhibition in the bipolar cell layer. The experiments in rabbits by vincristine intravenous and intravitreous administrations did not give rise to a negative type ERG, but to a decrease of the amplitude of all ERG components. The lesion of CSNB which was reported to be responsible in the synaptic terminal by Ripps et al could not be confirmed.

Aged↗

PubMedDate not supplied

Hexagonal structures at lens capsule zonular attachments.

Two years after uneventful phacoemulsification with posterior intraocular lens implant in an 84-year-old female patient, the capsular bag and enclosed intraocular lens luxated into the vitreous cavity. A vitrectomy was done to extract the lens and capsule for electron-microscopic examination. We found very few zonular attachments to the capsule, but did note hexagonal structures of unknown significance that our study indicates may be related to the lens epithelium.

Aged↗

PubMedDate not supplied

Uveitis-glaucoma-hyphema syndrome after posterior chamber intraocular lens implantation.

This article describes uveitis-glaucoma-hyphema (UGH) syndrome following posterior chamber intraocular lens (PCIOL) implantation in a 51-year-old male patient who had had intermittent blurred vision for 2 years prior to cataract surgery. We found the lens haptics fixed in the sulcus and the lens rotated. The lens was extracted and a new implant inserted with a transscleral suture. Etiology of the syndrome in this patient was an unstable sulcus fixation.

Glaucoma↗

PubMedDate not supplied

Retinal light damage: protective effect of alpha-tocopherol.

We studied histologically the protective effect of alpha-tocopherol to retinal light damage. After 3-week-old albino rats were fed with an alpha-tocopherol deficient or supplemented diet and kept in a 12-hour dim light/12-hour dark environment for 8 weeks, each animal was exposed to intense light (2500 lux) for 1, 3, 6, 12, 24, and 72 hours. The eyes were enucleated and prepared for transmission electron microscopy study and image analysis of phagosomes. Before light exposure, the alpha-tocopherol content of the neural retina of the deficient and supplemented groups was 0.3 microgram and 23.34 micrograms, respectively. After 1- and 3-hour exposures, morphological changes in the retinal pigment epithelium and photoreceptor membranes were more extensive in the deficient group than in the supplemented group. After a 24-hour exposure, pyknotic photoreceptor nuclei were more numerous in the deficient group than the supplemented group. After 3-, 6-, and 12-hour exposures, large phagosomes were more numerous in the deficient group than in the supplemented group. These findings suggest that alpha-tocopherol can protect the retina from light injury for up to 24 hours of exposure.

Animals↗

PubMedDate not supplied

Retinal cell death by light damage.

PURPOSE: To determine the relationship between apoptotic photoreceptor cell death and the duration of light exposure. METHODS: Ten-week-old male albino rats (Wistar strain) were dark-adapted for 2 days and then exposed to intense light for 12 hours, and 1, 2, 3, 7, 14, 21, and 28 days. The presence of apoptosis was confirmed by electron microscopy and the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) method. Differences in the apoptotic processes of the photoreceptor cells in the superior, posterior pole, and inferior portions of the retina were determined. RESULTS: Photoreceptor cells showed TUNEL-positive staining, whereas the cells in the inner nuclear layer, ganglion cell layer and retinal pigment epithelia exhibited weak positive or negative TUNEL staining. By electron microscopy, photoreceptor cells showed typical apoptotic nuclear changes and formation of apoptotic bodies. CONCLUSIONS: The sensitivity to light damage and style of death differed among retinal cells by location and cell type.

Animals↗