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Biomedical subjects

J Naito

Publications and source records attributed to J Naito.

At least 37 records · Page 2Linked to original sources
PubMed1999

Ommochrome deficiency in an albino strain of a terrestrial isopod, Armadillidium vulgare.

In order to clarify the cause of ommochrome deficiency in an albino strain of the terrestrial isopod, Armadillidium vulgare, levels of xanthommatin, 3-hydroxykynurenine, 3-hydroxyanthranilic acid and tryptophan in whole body extracts of the albino and the wild type individuals were determined together with enzyme activities of kynurenine-3-hydroxylase, kynureninase and tryptophan-2,3-dioxygenase. Xanthommatin could not be detected in the albinos. The levels of 3-hydroxykynurenine and 3-hydroxyanthranilic acid were determined by high-performance liquid chromatography (HPLC) with electrochemical detection and were markedly low in the albinos compared with the wild type individuals. In contrast to those, the tryptophan levels determined by HPLC with fluorescence detection did not differ significantly between the two phenotypes. In the albino A. vulgare, kynurenine-3-hydroxylase activity was lower and kynureninase activity was higher than in the wild type, although the differences were not statistically significant. Tryptophan-2,3-dioxygenase activity in the albinos was less than 10% that in the wild type. Thus, ommochrome deficiency in the albino A. vulgare is considered to be caused by the extremely low activity of tryptophan-2,3-dioxygenase.

3-Hydroxyanthranilic Acid↗
PubMed1999

A quantitative analysis of cells in the ganglion cell layer of the chick retina.

This study investigated the organization of cells in the ganglion cell layer (GCL) using Nissl staining, retrograde cell degeneration with axotomy of the optic nerve, and retrograde cell labeling by injections of horseradish peroxidase (HRP) into the optic nerve of chicks (posthatching day 1 and 8, P-1 and P-8). The total number of cells in the GCL was 6.1 x 10(6) (P-1) and 4.9 x 10(6) (P-8), and the cell density was 14,300 cells/mm2 (P-1) and 10,400 cells/ mm2 (P-8) on average. Two high-density areas, the central area (CA) and the dorsal area (DA), were observed in the central and dorsal retinas in both P-1 (22,000 cells/mm2 in CA, 19,000 cells/mm2 in DA) and P-8 chicks (19,000 cells/mm2 in CA, 12,800 cells/mm2 in DA). The cell densities in the temporal periphery (TP) and the nasal (NP) peripheral retinas were 7,800 cells/mm2 and 12,500 cells/mm2, respectively, in P-1 and 5,000 cells/ mm2 and 8,000 cells/mm2, respectively, in P-8 chicks. The cell density in the temporal periphery was 35% (P-8) lower than in the nasal periphery in both P-1 and P-8 chicks. Thirty percent (1.9 x 10(6) cells in P-1) of the total cells in the GCL were resistant to axotomy of the optic nerve. The distribution of the axotomy-resistant cells showed two high-density areas in the central and dorsal retinas, corresponding to the CA (5,800 cells/mm2) and the DA (3,200 cells/mm2). These cells also exhibited a center-peripheral increase (2,200 cells/mm2 in the TP) in P-1 chicks, but the high-density area was not found in the dorsal retina of P-8 chicks. From these data and the HRP study, the number of presumptive ganglion cells in P-8 chicks was estimated to be 4 x 10(6) (8,600 cells/mm2 on average), and the density in each area was 13,500 (CA), 10,200 (DA), and 4,300 (TP) cells/mm2. The peripheral/ center ratios of the density of ganglion cells were significantly different along the nasotemporal and dorsoventral axes. The density of ganglion cells decreased more rapidly toward the temporal periphery (TP/CA ratio: 0.47 in P-1 and 0.32 in P-8) than toward the nasal periphery (NP/CA ratio: 0.67 in P-1 and 0.52 in P-8). In contrast, there was no significant difference in the peripheral/center ratios between the dorsal retina (DP/CA ratio: 0.6 in P-1 and 0.56 in P-8) and ventral retina (VP/CA ratio: 0.58 in P-1 and 0.51 in P-8). A small peak in the density of the presumptive ganglion cells was detected in the dorsal retina of both P-1 chicks (10,800 cells/mm2) and P-8 chicks (10,200 cells/mm2). The HRP-labeled cells were small in the CA (M +/- SD: 35.7 +/- 9.1 microm2) and DA (40.0 +/- 11.3 microm2), and their sizes increased toward the periphery (63.4 +/- 29.7 microm2 in the TP) accompanied by a decrease in the cell density. However, the axotomy-resistant cells did not significantly increase in size toward the peripheral retina (12.2 +/- 2.2 microm2 in the CA, 15.2 +/- 3.2 microm2 in the DA, 15.1 +/- 3.8 microm2 in the TP). The characteristic distribution of ganglion cells could be related to visual behavior based upon the specialization of avian visual fields.

Animals↗
PubMed1999

Atrial ejection force in systemic autoimmune diseases.

Systemic autoimmune disorders may affect several organs, including the heart. We analyzed two-dimensional and pulsed Doppler echocardiograms of patients (n = 37) with systemic lupus erythematosus (SLE, n = 24) or rheumatoid arthritis (RA, n = 13) to determine whether atrial ejection force (AEF) could represent a suitable parameter for detecting left ventricular filling abnormalities in SLE and RA. In both patient subgroups, AEF was significantly higher than in healthy controls (n = 40) matched for gender and age (14.0 +/- 5.4 vs. 11.0 +/- 3.5 kdyn, p < 0.01). Because conventional echocardiographic parameters of left ventricular function failed to detect such a difference, AEF might serve as an additional sensitive parameter for detecting left ventricular diastolic filling abnormalities early in the course of a systemic autoimmune disease.

Adolescent↗
PubMed1999

Localization of sympathetic, parasympathetic and sensory neurons innervating the heart of the Beijing duck by means of the retrograde transport of horseradish peroxidase.

Sympathetic, parasympathetic and sensory neurons were labeled by injections of horseradish peroxidase into various regions of the heart in 33 Beijing ducks. Sympathetic postganglionic neurons innervating the heart were located in the paravertebral ganglia C15 (C16 is the last cervical segment in the duck) to T3, especially in the ganglion T1. The coronary sulcus and ventricle were more abundantly innervated by sympathetic neurons than the atrium. The left side of the heart was preferentially innervated by sympathetic postganglionic neurons in the left side of paravertebral ganglia but the right side of the heart were equally supplied from the right and left ganglia. Within the medulla oblongata, the number of labeled vagal preganglionic neurons in the nucleus ambiguus was much greater than that in the dorsal motor nucleus of the vagus nerve. Labeled neurons of the nucleus ambiguus were found in many ducks injected into the coronary sulcus. Cardiac sensory neurons were observed in the dorsal root ganglia C15 to T2 (highest in the ganglion T1) and in the nodose and jugular ganglia of the vagus nerve. These labeled neurons probably form the afferent and efferent limbs of cardiac reflexes and control circulation in the Beijing duck.

Animals↗
PubMed1999

Morphological classification of ganglion cells in the central retina of chicks.

Classification of retinal ganglion cells (RGCs) in the chick central retina was studied by retrograde labeling of carbocyanine dye (DiI) and intracellular filling with Lucifer Yellow. Ganglion cells were divided into 4 groups, Group Ic/Is, Group IIc/IIs, Group IIIs, Group IVc, according to sizes of somal area and dendritic field and dendritic branching pattern. Group I cells had small somal area and small dendritic field. They were further divided into 2 subgroups by complexity (subgroup Ic) and simplicity (subgroup Is) of the dendritic arborization. Group II cells had medium-sized soma and dendritic field. They were also divided into subgroup IIc and IIs by the same definitions as those of subgroup Ic and Is. Group IIIs had medium-sized soma, large and simple dendritic arborization. Group IVc in which all cells had large soma, showed large and complex dendritic arborization. Cell populations of each group were 51.8% (subgroup Ic), 21.1% (subgroup Is), 6.2% (subgroup IIc), 14.6% (subgroup IIs), 4.2% (Group IIIs), and 2.1% (Group IVc). Subgroup Ic cells, which were very similar to beta-cells in the mammalian central area, represented about a half of the ganglion cell population. Cells in subgroup Is and IIs, which were not reported in the mammalian retina, were found in the chick central retina in relatively high population (35.7%). Morphological features of chick RGCs in the central retina were considered in comparison with those of other vertebrates.

Amidines↗
PubMed1998

Somatotopic representation within the facial motor nucleus of the chicken studied by means of horseradish peroxidase.

The distribution in the chicken of motoneurons innervating the hyolingual muscles, i.e. the M. branchiomandibularis (BM), M. ceratoglossus (CG), M. interceratobranchialis (CB), M. serpihyoideus (PH), M. stylohyoideus (YH) and one of the mandibular muscles, M. depressor mandibulae (DM), was examined by retrograde transport of horseradish peroxidase conjugated with wheatgerm agglutinin. Labelled motoneurons are found in the three subnuclei of the facial (VII) nucleus, as well as hypoglossal (XII) nucleus. The distribution of motoneurons projecting to the DM are observed in the three subnuclei, those of the BM, PH and YH in the intermediate and ventral subnuclei and those of the CB and CG in the intermediate subnucleus. Motoneurons projecting to the PH, YH, CB and CG are also distributed in the XII nucleus. The ratio of labelled motoneurons of the VII to XII nuclei decreases the PH, YH, CB and CG in that order, and the ratio of labelled ones of the ventral to intermediate subnuclei decreases the BM, PH and YH in that order. The topographical and functional aspects of the subdivision of the motor nucleus are discussed.

Animals↗
PubMed1998

Open eyelids at birth, a new mutation in the musk shrew, Suncus murinus.

The mutation designated "open eyelids at birth" arose spontaneously in the BAN strain of the musk shrew (Suncus murinus). This is the first report on this kind of mutation in the shrew. Mating experiments suggested that the mutant character is controlled by an autosomal recessive gene with about 43% penetrance. The symbol oeb(open eyelids at birth) was proposed for the mutant gene. Affected shrews were fully viable and fertile. Phenotypically, the affected shrews were characterized by one or both eyelids open at birth. By 9 days of age, the exposed and dried eyeballs usually dropped off and became missing or sometimes looked microphthalmic. Except for the eye abnormality, the affected shrews showed no obvious external abnormalities. Light-microscopically, the affected shrews with missing eyes or microphthalmia-like eyes did not have complete eye structures, and only remnants of some eye tissue were observed. In the phenotypically normal oeb/oeb shrews with closed eyelids at birth, no histological eye abnormalities were noted. Thus, the mutant character observed may simply be caused by a failure of the eyelids to close.

Animals↗
PubMed1998

Ultrastructure of enkephalin- and substance P-immunoreactive axon terminals in the hypoglossal nucleus of the chicken.

The morphology and distribution of leucine-enkephalin (LENK)- and substance P (SP)-containing axon terminals in the hypoglossal nucleus of the chicken was investigated immunocytochemically at the electron microscopic level. The major findings of the present study were as follows: 1) Both LENK- and SP-immunoreactive (IR) profiles including unmyelinated axons, varicosities and axon terminals were found throughout the hypoglossal nucleus. 2) LENK-IR profiles without synapses (preterminal axons and varicosities) were observed more frequently (66%) than LENK-IR synaptic profiles (34%). In contrast, SP-IR synaptic terminals were seen more often (68%) than SP-IR terminals without synapses (32%). 3) Both LENK- and SP-IR synaptic terminals ending on dendrites were more numerous (83% and 94%, respectively) than those making synapses on somata (17% and 6%, respectively). 4) The average diameter of SP-IR synaptic terminals were significantly larger than that of LENK-IR ones. 5) Both LENK- and SP-IR synaptic terminals contained numerous small clear vesicles and several large dense-cored vesicles (LDV). Although both LENK- and SP-IR synaptic terminals contained LDV consistently, SP-IR synaptic terminals contained significantly more LDV than LENK-IR types. 6) Postsynaptic dense bodies (Taxi bodies) were seen more frequently in SP-IR synaptic terminals than in LENK-IR ones. These findings confirm both LENK and SP innervation in the hypoglossal nucleus and suggest a functional role as neuromodulator for the two neuropeptides in tongue control.

Animals↗
PubMed1997

Prediction of the changes in cardiac output in association with preload reduction therapy in patients with hypertensive heart failure.

In treating patients with acute hypertensive heart failure we often try preload-reduction therapy using diuretics or vasodilators, but this may frequently produce a considerable decrease in cardiac output, particularly in hypertensive patients with diastolic dysfunction. Therefore, it is important from the clinical standpoint to predict the change in cardiac output following preload-reduction therapy. The objective of this study was to assess whether the change in cardiac output in association with preload-reduction therapy is predictable before treatment by analysis of mitral flow velocity patterns in patients with hypertensive heart failure. Changes in left ventricular volumes and cardiac output in association with preload-reduction therapy and Doppler echocardiographic parameters of the mitral flow velocity pattern before treatment were studied in 18 patients with hypertensive heart failure. Cardiac output increased in six patients with systolic dysfunction (fractional shortening < 25%). In the other 12 patients (those with normal systolic function), the changes in cardiac output were homogenous among the patients. In this subset there was a greater decrease in cardiac output in patients with a shorter deceleration time. Thus, analysis of deceleration time of the early diastolic filling wave before treatment may be useful in estimating the change in cardiac output following preload reduction in patients with hypertensive heart failure due to diastolic dysfunction.

Adult↗
PubMed1997

Insights into the mechanism of the nitroprusside-induced increase in cardiac output in failing hearts: an attempt at its prediction with Doppler echocardiography.

Increased left ventricular (LV) diastolic pressure is consistently decreased by the administration of nitroprusside; however, nitroprusside-induced changes in cardiac output (CO) vary among patients with failing hearts. Although the variation has been considered to be related to interindividual inhomogeneity of LV diastolic performance, nitroprusside-induced changes in CO are not predictable before drug administration in individual subjects. We attempted to clarify whether nitroprusside-induced changes in CO may be predicted by analysis of the mitral flow velocity pattern in failing hearts. LV diastolic pressure was increased by the combination of the decrease in LV function and the volume expansion, and 15 conditions with LV end-diastolic pressure (EDP) > or =15 mm Hg were obtained in 8 dogs. In each condition, pulsed Doppler mitral flow velocity patterns were recorded simultaneously with hemodynamic variables before and during intravenous nitroprusside infusion. After nitroprusside administration, LV systolic pressure and LVEDP decreased in all dogs, and CO increased in eight conditions but decreased in seven conditions. CO was more likely to increase with administration of nitroprusside, and its change was greater in the conditions in which deceleration time of the early diastolic filling wave before nitroprusside infusion was longer (r = 0.56, p<0.05, n = 15). Better correlation was obtained with multiple-regression analysis, using the deceleration time and peak filling velocity at atrial contraction (r = 0.67, p<0.05, n = 15). The deceleration time correlated with LV dynamic compliance (r = 0.66, p<0.01, n = 30). Analysis of mitral flow velocity patterns may be useful in predicting nitroprusside-induced changes in CO in failing hearts.

Animals↗
PubMed1997

Genetic and biochemical studies on ommochrome genesis in an albino strain of a terrestrial isopod, Armadillidium vulgare.

Genetic studies and quantitative determination of levels of 3-hydroxykynurenine and kynurenine were performed in an albino strain of a terrestrial isopod Armadillidium vulgare. From the results of matings between the albino and the albino, the red, the dark red, or the wild type individuals, the albino A. vulgare seems to be regulated by an autosomal gene(s) recessive to its wild allele. Litter mating of F1 progenies obtained by crossing the albino and the red mutant or the albino and the dark red mutant yielded progenies at a ratio of 3:6:3:4 for the red, the dark red, the wild, and the albino phenotypes, respectively. The albino gene(s) seems not to be allelic but to be epistatic to the red gene(s) with respect to ommochrome biosynthesis. Quantitative determination of 3-hydroxykynurenine carried out by high-performance liquid chromatography with electrochemical detection revealed that the 3-hydroxykynurenine content in the albino was significantly lower than that in the wild or the red type. The whole content of 3-hydroxykynurenine after enzymatic conversion of kynurenine to 3-hydroxykynurenine was still considerably lower than that found in the wild type, even though it increased after the conversion. The albino gene(s) seems to be associated with a blockage at distinct level(s) of ommochrome biosynthesis.

Albinism↗
PubMed1997

Distributions of the cardiac plexuses and ganglia in the Beijing duck.

Distributions of the cardiac plexuses and cardiac ganglia were gross-anatomically and histologically studied in eight Beijing ducks. The cardiac plexuses consisted of two components, the cardiac nerve arising from the sympathetic trunk and the cranial and caudal cardiac nerves arising from the vagus. Branches of these nerves made the cardiac plexuses on the epicardium. The cardiac plexuses could be divided into the six plexuses, that is, the right and left coronary plexuses, pericardiac transverse sinus plexus, caudal cardiac plexus, and right and left superior cardiac plexuses. There were small ganglia in the caudal cardiac plexus and the right and left coronary plexuses. These ganglia containing multipolar neurons were found like a linking chain in a single nerve.

Animals↗
PubMed1997

Distribution of neuropeptide-immunoreactive nerve fibres in the medulla oblongata of the chicken.

The anatomical distribution of nerve fibres containing galanin (GAL), leucine enkephalin (lENK), methionine enkephalin (mENK) and substance P (SP) was investigated in the medulla oblongata of the chicken by means of immunohistochemistry. In the medulla oblongata, dense networks of mENK-, lENK-, SP- and GAL-immunoreactive nerve fibres were mainly restricted within and around the dorsal vagal complex, i.e., the nucleus of the solitary tract and dorsal motor nucleus of the vagus nerve. The relative density of immunoreactive nerve fibres was usually decreased in the order of mENK-, SP-, lENK- and GAL-immunoreactive ones. Immunoreactive nerve fibres for each antiserum had a unique distribution among the subnuclear groups of the dorsal vagal complex. Sparser networks of immunolabelled nerve fibres were found in the nucleus of the hypoglossal nerve, nucleus ambiguus, nucleus of the descending trigeminal tract, raphe nucleus and caudal olivary complex. In the colchicine-pretreated chicken, some nerve cell bodies expressing the immunoreaction for ENK and GAL antisera were detected in the nucleus of the solitary tract and nucleus of the descending trigeminal tract. There were some differences in the distribution pattern of immunoreactive nerve elements among the four kinds of antisera. The selective distribution of neuropeptide-containing nerve elements within various nuclei of the medulla oblongata suggests that these neuropeptides may be differentially involved in central neural regulation.

Animals↗
PubMed1996

Cells of origin of spinal projections from the paraventricular nucleus (PVN) of the hypothalamus in the chicken.

Hypothalamic neurons projecting to the lumbar (lumbar-neurons) and sacral (sacral-neurons) segments were retrogradely labeled by injections of fluorescent axonal tracers (FITC-WGA, TRITC-WGA) into both the lumbar and sacral segments. Labeled neurons were distributed in the principal part of the paraventricular nucleus (PVN), but not in the pars dispersa of this nucleus. Of these neurons, some small and oval-shaped neurons (about 10 microns in diameter) in a middle part of the PVN were observed to be labeled by both FITC-WGA and TRITC-WGA (lumbosacral-neurons) suggesting double projections to lumbar and sacral segments.

Animals↗
PubMed1996

Morphological and quantitative analysis of the fascicular pattern of monkey optic nerve.

Fascicular formation by processes of astrocytes was investigated immunohistochemically with an antibody against glial fibrillary acidic protein in the monkey optic nerve. Fascicular patterns were analyzed using an image analyzer. A steep decrease in total fascicular number, following "fusion" of small fascicles, was seen in the rostral part of the optic nerve; this became more gradual in the caudal part of the optic nerve. Just behind the eyeball, most of the fascicles were small (75.4% of all fascicles, n=958); these decreased sharply in number (16.7% of all fascicles) in the rostral part of the optic nerve. In contrast, the numbers of the middle-sized, large, and largest fascicles increased gradually in the rostral part of the optic nerve. The fascicular number in each fascicular group was constant at the caudal part of the optic nerve, except for the largest fascicles, which varied in number throughout the optic nerve. The change in fascicular size along the optic nerve was strikingly similar to that of the fiber dispersion. Distribution patterns of the small and middle-sized fascicles were different from that of the largest fascicles, which were preferentially distributed at the periphery of the optic nerve. The pattern of fascicular distribution according to size seemed to be related to the centroperipheral retinotopic fiber order.

Animals↗
PubMed1996

Influence of preload, afterload, and contractility on myocardial ultrasonic tissue characterization with integrated backscatter.

Influence of hemodynamic changes in preload, afterload and contractility on myocardial integrated backscatter (IB) was studied in 26 adult mongrel dogs by measuring myocardial IB calibrated with the backscatter from the blood during volume infusion (preload alteration), during aortic constriction (afterload alteration), and during dobutamine or propranolol infusion (contractility alteration). Changes in preload, afterload or contractility did not significantly affect the calibrated myocardial IB either in the septum or in the posterior wall. Changes in preload and afterload did not affect the magnitude of cyclic variation in IB. However, dobutamine produced a significant increase in the magnitude of cyclic variation in IB and propranolol significantly decreased the magnitude of cyclic variation in IB. These data indicated that the calibrated myocardial IB is independent of preload, afterload and contractility, and that the magnitude of cyclic variation in IB is influenced by contractility. We may estimate static (related to histological changes such as fibrosis, edema, necrosis, and so on) and dynamic (related to myocardial contraction such as sarcomere length, muscle fiber orientation, and so on) properties of the myocardium more precisely using myocardial IB calibrated with the backscatter from the blood in addition to the magnitude of cyclic variation in IB.

Adrenergic beta-Agonists↗
PubMed1996

Analysis of transmural trend of myocardial integrated ultrasonic backscatter in patients with old myocardial infarction.

Changes in myocardial integrated backscatter (IB) reflect myocardial viability in patients with myocardial infarction. IB may be obtained separately in the subendocardial and subepicardial layers to establish a transmural trend. The purpose of this study is to examine the possibilities that the measurement of the transmural trend in myocardial IB may provide a new estimate of transmurality of infarction in patients with old myocardial infarction. A calibrated myocardial IB and its transmural trend were measured both in the septum and posterior wall in 21 normal subjects, 24 patients with anteroseptal old myocardial infarction (13 patients with Q-wave myocardial infarction and 11 patients with non-Q-wave myocardial infarction). The transmural trend in myocardial IB was assessed by measuring the acoustic parameter separately in the right and left ventricular halves of the septum, and in the endocardial and epicardial halves of the posterior wall. The magnitude of cyclic variation of IB (a difference between minimum and maximum peaks) was lower, and calibrated myocardial IB (the maximum value of myocardial IB at end diastole calibrated with the power of Doppler signals from the blood along the same ultrasound beam) was higher in patients with anteroseptal old myocardial infarction in the septum, compared with normal subjects. Among patients with myocardial infarction, the difference in these IB parameters between the right and left ventricular halves of the septum was found only in patients with non-Q-wave myocardial infarction. The transmural trend of myocardial IB was likely to reflect the transmurality of myocardial infarction. Therefore, our data give another insight into the assessment of transmural inhomogeneity of myocardial fibrosis or viability in patients with myocardial infarction.

Aged↗