Biomedical subjects

K Takenouchi

Publications and source records attributed to K Takenouchi.

At least 19 recordsLinked to original sources

PubMed2001

Aberrant brain activation following motor skill learning in schizophrenic patients as shown by functional magnetic resonance imaging.

BACKGROUND: Motor skill learning may be impaired in schizophrenia. While functional brain imaging studies have shown reduced activation during motor task performance in schizophrenic patients, brain activity changes with motor skill learning in these patients have not been studied by functional imaging. METHODS: A sequential complex motor task involving the right hand was performed by nine medicated schizophrenic patients and 10 age-matched healthy controls. Functional magnetic resonance images were obtained using a gradient echo, echoplanar imaging (EPI) pulse sequence before and after 1 week of training in performing the task. RESULTS: Bilaterally, patients showed significantly less blood oxygenation level-dependent (BOLD) signal response in the premotor area (PMA) before beginning motor training than controls. BOLD signal response increased in the left PMA of schizophrenic patients after 1 week of motor training; in contrast, the signal decreased in the left PMA of control subjects. Training effects concerning the number of finger movement sequences achieved did not differ between groups. Daily neuroleptic dose did not significantly affect changes with training in BOLD signal response in the PMA. CONCLUSIONS: These preliminary results suggest that schizophrenic patients have dysfunction of neural networks in areas including the PMA that are involved in executing a complex motor task. In terms of brain activity, motor learning may be less efficient or slower in the patients than in healthy subjects.

Adolescent↗

PubMed2000

Reciprocal information flow between prefrontal cortex and ventral tegmental area in an animal model of schizophrenia.

The medial prefrontal cortex (PFC) is anatomically and functionally connected with the ventral tegmental area (VTA), the neuronal source of mesocorticolimbic system that is pathophysiologically related to schizophrenia-like symptoms. Methamphetamine (MAP) was applied to examine the functional relationship between PFC and VTA in an animal model of schizophrenia. Hyperactivity and stereotyped behavior were observed accompanied by a distinctive direction of information flow. In hyperactivity, information flow in the direction from PFC to VTA was dominant. Contrarily, dominant information flow from VTA to PFC was found in stereotyped behavior. These results indicate that dysfunctional interaction between PFC and VTA is the neuronal basis of MAP-induced schizophrenia-like psychosis. The information flow and its direction can be useful tool to explain the neurogenesis of these abnormal behaviors.

Animals↗

PubMed2000

Directed coherence of EEG on ICSS rats with methamphetamine-induced hyperactivity and stereotyped behavior.

Methamphetamine (MAP) can reinforce intracranial self-stimulation (ICSS) in rats, that is, reward-seeking behavior. However, the ICSS can be inhibited by the stereotyped behavior induced by MAP. This study was designed to observe the mutual information flow between prefrontal cortex (PFC) and ventral tegmental area (VTA) using directed coherence (DC) analysis during the hyperactivity and stereotyped behavior induced by administration of MAP (a derivative of amphetamine). The DC from PFC to VTA increased at 5-7 Hz in the hyperactivity as compared to the stereotypy. In contrast, enhanced information flow from VTA to PFC was observed in the stereotypy as compared to the hyperactivity. We found a reciprocal information flow between PFC and VTA corresponding to the hyperactivity and stereotyped behavior that was induced by administration of MAP.

Animals↗

PubMed2000

An efficient method for production of uridine 5'-diphospho-N-acetylglucosamine.

Uridine 5'-diphospho-N-acetylglucosamine (UDP-GlcNAc) has been synthesized by a yeast-based method from 5'-UMP and glucosamine, in which yeast cells catalyze the conversion of 5'-UMP to 5'-UTP and provide enzymes involved in UDP-GlcNAc synthesis using 5'-UTP and glucosamine as substrates. However, this conventional method is not suitable for practical production of UDP-GlcNAc because of the low yield of the product. We found that the yqgR gene product of Bacillus subtilis, which has been identified as a glucokinase, can catalyze the phosphorylation of N-acetylglucosamine (GlcNAc) to give GlcNAc-6-phosphate, an intermediate of UDP-GlcNAc biosynthesis. The addition of the yqgR gene product to the yeast-based reaction system enabled us to synthesize UDP-GlcNAc using GlcNAc in place of glucosamine. The addition of two enzymes, GlcNAc-phosphate mutase and UDP-GlcNAc pyrophosphorylase, increased the yield of UDP-GlcNAc. Using this novel method, UDP-GlcNAc was produced at an amount of 78 mM from 100 mM 5'-UMP and 100 mM GlcNAc.

Amino Acid Sequence↗

PubMed2000

Organization of extracellular matrix components during differentiation of adipocytes in long-term culture.

Scanning electron microscopy (SEM) observation showed that fully differentiated spherical adipocytes were embraced by a network of collagens and fibroblastic preadipocytes. The properties of both the collagen networks and the preadipocytes allow the adipocytes to be interconnected, forming a fat-cell cluster, which can anchor to the bottom of a culture dish. In this network structure, collagen fibrils and fibrillar bundles were closely arranged and stratified. We found that immunostained collagens appeared to form extracellular network structures, which can be observed by SEM. The extracellular network of fibronectin was the first to develop among the extracellular matrix (ECM) components, though it became degraded with the progress of adipocyte differentiation. The type I collagen network was the last to develop and remained well organized through the late stage of adipocyte differentiation. The extracellular networks of type III, V, and VI collagen developed by the mid-stage and remained in the late stage of adipocyte differentiation. The network structures of type IV collagen and laminin became degraded during the differentiation process and localized at the surface of spherical cells. In addition to these basement membrane components, types III, V, and VI collagens also showed pericellular spherical staining patterns. These results demonstrated that the constitution and distribution of the ECM are altered during adipocyte differentiation, suggesting that the organization of each ECM component into a suitable structure is a requirement for the differentiation and maintenance of unilocular adipocytes.

Adipocytes↗

PubMed1999

Effect of intraduodenal lipid on parabrachial gustatory coding in awake rats.

Intestinal fat differentially suppresses sham feeding of liquid diets and preferred gustatory stimuli. Although the behavioral effect is robust, no electrophysiological evidence exists to account for its neural basis. Therefore, we investigated the effect of intestinal fat on gustatory coding in the pontine parabrachial nuclei (PBN) by recording from single neurons in awake rats before, during, and after intraduodenal infusions of lipid (Intralipid; 10 ml, 5 kcal). Intraduodenal lipid did not alter the response profiles of PBN taste neurons. It did, however, produce an overall decrease in response magnitude (-16.25%; n = 43), with the largest reduction to sucrose (-30%; n = 43). The most pronounced suppression occurred in sucrose-best neurons in response to sucrose (-55%; n = 19), and this effect was largest for the sucrose-specific cells (-77%; n = 3). After lipid infusions, nonspecific neurons in both the sucrose-best and NaCl-best categories also responded less to their best stimulus (sucrose, -46%; n = 16; NaCl, -35%; n = 13). In contrast, no significant changes were found in NaCl-specific cells in response to NaCl. All effects appeared with short latency ( approximately 5 min) and were reversible within the time frame of a meal. In controls, duodenal infusions of saline did not cause any changes in taste responsiveness. These results suggest that intestinal fat has specific effects on taste coding in the PBN that may contribute to the intake suppression of palatable food observed in behavioral studies. The similar, short latency of both the behavioral and neural effects supports the hypothesis of a preabsorptive site of action.

Animals↗

PubMed1999

Emotional and behavioral correlates of the anterior cingulate cortex during associative learning in rats.

Neuronal activity was recorded from the anterior cingulate cortex of behaving rats during discrimination and learning of conditioned stimuli associated with or without reinforcements. The rats were trained to lick a protruding spout just after a conditioned stimulus to obtain reward (intracranial self-stimulation or sucrose solution) or to avoid aversion. The conditioned stimuli included both elemental (auditory or visual stimuli) and configural (simultaneous presentation of auditory and visual stimuli predicting reward outcome opposite to that predicted by each stimulus presented alone) stimuli. Of the 62 anterior cingulate neurons responding during the task, 38 and four responded differentially and non-differentially to the conditioned stimuli (conditioned stimulus-related neurons), respectively. Of the 38 differential conditioned stimulus-related neurons, 33 displayed excitatory (n = 10) and inhibitory (n = 23) responses selectively to the conditioned stimuli predicting reward. These excitatory and inhibitory differential conditioned stimulus-related neurons were located mainly in the cingulate cortex areas 1 and 3 of the rostral and ventral parts of the anterior cingulate cortex, respectively. The remaining 20 neurons responded mainly during intracranial self-stimulation and/or ingestion of sucrose (ingestion/intracranial self-stimulation-related neurons). Increase in activity of the ingestion/intracranial self-stimulation-related neurons was correlated to the first lick to obtain rewards during the task, suggesting that the activity reflected some aspects of motor functions for learned instrumental behaviors. These ingestion/intracranial self-stimulation-related neurons were located sparsely in cingulate cortex area 1 of the rostral part of the anterior cingulate cortex and densely in frontal area 2 of the caudal and dorsal parts of the anterior cingulate cortex. Analysis by the multidimensional scaling of responses of 38 differential conditioned stimulus-related neurons indicated that the anterior cingulate cortex categorized the conditioned stimuli into three groups based on reward contingency, regardless of the physical characteristics of the stimuli, in a two-dimensional space; the three conditioned (two elemental and one configural) stimuli predicting sucrose solution, the three conditioned (two elemental and one configural) stimuli predicting no reward, and the lone conditioned stimulus predicting intracranial self-stimulation. The results suggest that the anterior cingulate cortex is organized topographically; stimulus attributes predicting reward or no reward are represented in the rostral and ventral parts of the anterior cingulate cortex, while the caudal and dorsal parts of the anterior cingulate cortex are related to execution of learned instrumental behaviors. These results are in line with recent neuropsychological studies suggesting that the rostral part of the anterior cingulate cortex plays a crucial role in socio-emotional behaviors by assigning a positive or negative value to future outcomes.

Acoustic Stimulation↗

PubMed1999

Effects of D1 and D2 dopamine receptor antagonists on cocaine-induced self-stimulation and locomotor activity in rats.

To clarify the involvement of D1 and D2 dopamine systems in intracranial self-stimulation (ICSS) and locomotor activity in rats, we studied the acute effects of cocaine and the interaction between cocaine and dopamine antagonists with respect to these behaviors. Although cocaine (5.0, 10.0, or 20.0 mg/kg) dose-dependently increased locomotor activity, it augmented the rate of ICSS only at 5.0 mg/kg. The failure of high doses of cocaine to augment purpose-oriented behavior such as ICSS may result from its induction of a manic-like state. The D1 dopamine receptor antagonist SCH23390 (0.02, 0.1, or 0.5 mg/kg) or the D2 antagonist nemonapride (0.04, 0.2, or 1.0 mg/kg) significantly decreased cocaine augmentation of ICSS. The higher two doses of either antagonist also produced a significant decrease in cocaine-induced locomotor activity. We therefore suspect that cocaine's augmentative effect on those behaviors, especially ICSS, requires activation of both D1 and D2 dopamine receptors.

Animals↗

PubMed1999

Lateralized memory deficits on the Wada test correlate with the side of lobectomy only for patients with unilateral medial temporal lobe epilepsy.

The aim of this study was to determine whether the predictive value of the intracarotid amobarbital test (IAT) for the side to be resected is applicable only to medial temporal lobe epilepsy and to investigate whether there are different patterns of memory performances on the IAT between patients with unilateral mesial temporal sclerosis (UMT group) and those without (non-UMT group). We studied 30 patients in the UMT group and 10 in the non-UMT group, who underwent pre-surgical evaluation for intractable temporal lobe epilepsy. Memory performances on the IAT was defined as the percentage of memory items presented during unilateral hemispheric anesthesia that was recognized after recovery. More than a 20% decline of the memory performance on the IAT compared with the memory performance on the pre-test was regarded as a memory deficit. Age at onset of epilepsy was significantly younger in the UMT than in the non-UMT group. Surgical outcome was significantly better in the UMT than in the non-UMT group. The lateralizing value of unilateral memory deficits on the IAT was statistically confirmed. There was a significant association between falsely lateralizing memory performances and the non-UMT group. Excluding the exceptional cases with right-sided language dominance in spite of right-sided lesions, the high incidence of the unilateral right-sided memory deficits in the non-UMT group was statistically significant. This study suggested that the excellent lateralizing value of the memory performances on the IAT is limited to patients with mesial temporal lobe epilepsy. IAT memory performances in patients without such lesions can be misleading, even if lateralized, because their memory status presumably reflects a natural lateralization of the memory organization which is independent of the epileptogenic focus.

Adult↗

PubMed1997

Novel naphthalene derivatives as inhibitors of human immunoglobulin E antibody production.

A series of naphthalene derivatives with a variety of substituents at the 2-position was prepared in order to evaluate their suppressive effect on immunoglobulin E (IgE) antibody production by human peripheral blood mononuclear cells provoked with anti-CD40 antibody (alpha-CD40), interleukin-4 (IL-4), and interleukin-10 (IL-10). Compounds having a 1,4-phenylene spacer moiety tethered between the 2-naphthyl nucleus and anthranilic acid suppressed IgE antibody production in vitro in preference to that of IgG antibody without affecting cell viability. Deletion of the anthranilic acid moiety diminished the inhibitory activities. Changing the 2-naphthyl to a 1-naphthyl or phenyl nucleus led to no change in the potency, indicating that the aromatic group at this position is indispensable for the inhibitory activities. On the other hand, changing the 1,4-phenylene spacer to a 1,3-phenylene one resulted in reduced potency. Similarly, inhibitory activities were lost when the CO2H moiety at the 2-position was moved to the 3- or 4-position on the terminal benzene. These observations suggest that the conformation around the anthranilic acid moiety affects the inhibitory activities toward IgE biosynthesis. 2-(4-(2-Naphthyloxy)benzamido)benzoic acid (29) seemed to be a more potent inhibitor of IgE production than of IgG production. Insertion of a methylene between the inter-phenylene and the amide moiety resulted in 2-((4-(2-naphthyloxy)phenyl)acetamido)benzoic acid (31), which provided a stronger inhibition of both IgE and IgG production, although the selectivity toward IgE was lower than that of 29. Introduction of a benzyl group at the 6-position on the naphthalene ring considerably increased the inhibitory activity toward IgE production with an IC50 of 8.3 nM (36). The potency of 31 and 36 was retained when hydrocortisone or lipopolysaccharide was used instead of alpha-CD40 and IL-10 as costimulatory factors with IL-4, implying that these compounds may interfere with signal transduction between IL-4/IL-4 receptor cognition and genetic transcription that induce class-switching of immunoglobulin in B cells. These novel naphthalene derivatives are thus excellent candidates for further investigation with a view toward a therapeutic remedy against IgE-mediated allergic diseases.

Antibody Formation↗

PubMed1997

Hippocampal volume asymmetry and age at illness onset in males with schizophrenia.

To determine whether there are disturbances of hippocampal volume asymmetry in schizophrenic patients, we obtained contiguous, 1-mm-thick magnetic resonance images in 28 males with chronic schizophrenia and in 28 age-matched healthy males. The schizophrenic patients showed a bilateral reduction in volume of the hippocampal formation (HF; left 7.0%; right 8.7%). This reduction was significantly associated with the severity of disorganization syndrome (P < 0.0005). A significant asymmetry in the HF volume was found in the control subjects (P = 0.006), but not in the patients (P = 0.40). There was a significant positive correlation between the asymmetry index and the patient's age at the onset of schizophrenia (r = 0.46, P = 0.01). Results indicate that a disturbance in the normal asymmetry of the HF may be a characteristic in schizophrenia, particularly in patients with an early onset of the illness.

Adult↗

PubMed1997

Metabolite changes with age measured by proton magnetic resonance spectroscopy in normal subjects.

To determine whether there are metabolite changes in the left medial temporal and frontal lobes with aging, we performed proton magnetic resonance spectroscopy in 36 normal subjects. The N-acetylaspartate/creatine-phosphocreatine ratio in the medial temporal lobe tended to be decreased in subjects over 60 years of age. The ratio decrease in the frontal lobe related to aging was lower than that in the medial temporal lobe. There were no significant differences in the metabolite ratios between males and females. These findings suggest that structures in the medial temporal lobe may be more susceptible to neuronal dysfunction associated with aging than those in the frontal lobe.

Adult↗

PubMed1997

Case of propylthiouracil-induced vasculitis associated with anti-neutrophil cytoplasmic antibody (ANCA); review of literature.

A 39-year-old Japanese woman had been receiving propylthiouracil for 5 years for hyperthyroidism when she developed myalgia, scleritis, proteinuria, fever, and inflammation of the nose. Examination of a renal biopsy specimen showed focal segmental necrotizing glomerulonephritis. Indirect immunofluorescent staining showed a highly positive perinuclear pattern of anti-neutrophil cytoplasmic antibody (ANCA) in her serum. Enzyme-linked immunosorbent assay (ELISA) of the ANCA showed positivity for anti-proteinase 3, anti-myeloperoxidase, anti-leukocyte elastase, and anti-lactoferrin, but anti-cathepsin G and anti-lysozyme were negative. Because ELISA showed the titer of anti-leukocyte elastase antibody to be markedly elevated, we challenged this data by performing dot blot analysis. The patient's serum reacted with the native form, but not with denatured leukocyte elastase. Propylthiouracil-induced vasculitis was suspected. Symptoms abated within 2 weeks and all values of ANCA were reduced after the drug was withdrawn. Vasculitis is a rare side-effect of propylthiouracil therapy. Recently it was reported in association with ANCA. We present the findings of this patient and compare them with those described in 19 published cases of propylthiouracil-induced vasculitis associated with ANCA.

Adult↗

PubMed1995

Beneficial effects of a novel anti-hypoxemic agent, TEI-7322, on bleomycin-induced experimental hypoxemia in rats.

Almitrine bismesylate is known to be an anti-hypoxemic agent that acts via the enhancement of hypoxic pulmonary vasoconstriction. However, screening for this class of compounds has been minimal, owing, in part, to a lack of convenient hypoxemic models in small animals. The present study was designed to establish a convenient model of hypoxemia induced by bleomycin and to evaluate anti-hypoxemic agents including a newly synthesized compound. TEI-7322, 2-allylamino-4-tert-butyl-amino-7-methyl-7H-pyrrolo[2,3- d]pyrimidine hydrochloride by using this model. Bleomycin was intratracheally instilled into rats. After 3 weeks, the arterial blood gas pressures were monitored in the animals in the conscious state. Then, prednisolone, doxapram, almitrine or TEI-7322 was administered to the bleomycin-treated rats to monitor changes in arterial blood gas pressures. Bleomycin-treated rats showed a decrease in the arterial blood O2 pressure (PaO2). The blood CO2 pressure (PaCO2) increased, along with an increase in the alveolar-arterial oxygen difference (AaDO2). These blood gas pressures in bleomycin-treated rats were not affected by treatment with prednisolone. Doxapram decreased the PaCO2 but did not change the PaO2. However, administration of almitrine or TEI-7322 significantly improved the PaO2 of bleomycin-treated rats with a decrease in the PaCO2. In conclusion, (1) bleomycin-induced lung injury causes hypoxemia in rats, probably resulting from ventilation-perfusion inequality; thus this model may be useful for evaluating anti-hypoxemic agents; and (2) TEI-7322, as well as almitrine, showed anti-hypoxemic effects in this model with different properties from those of doxapram, possibly due to improvement of ventilation-perfusion inequality, indicating that TEI-7322 may be a potent candidate for the treatment of hypoxemia.

Almitrine↗

PubMed1995

Impaired water barrier function in acne vulgaris.

In acne vulgaris, abnormal follicular keratinization is important for comedo formation, yet the precise mechanisms of comedogenesis are not known. The present study examined the interrelationship between sebum secretion rate (SSR), lipid content and water barrier function (WBF) of the stratum corneum (SC) in 36 acne patients and 29 control subjects. All major SC lipid classes were separated and quantified by thin-layer chromatography/photodensitometry. WBF was evaluated by measuring transepidermal water loss (TEWL), and the hygroscopic properties and waterholding capacity of the SC. The SSR over a period of 3 h was significantly higher in patients with moderate acne than in control subjects, but no significant difference was noticed between patients with mild acne and control subjects. Significant differences between patients with both moderate and mild acne and control subjects were noted in the amount of sphingolipids (ceramides and free sphingosine), but not for any other lipid classes. Furthermore in acne patients, lower amounts of sphingolipids were observed corresponding with a diminished WBF. These results suggest that an impaired WBF caused by decreased amounts of ceramides may be responsible for comedo formation, since barrier dysfunction is accompanied by hyperkeratosis of the follicular epithelium.

Acne Vulgaris↗

PubMed1995

Shortening of the hippocampal formation in first-episode schizophrenic patients.

Shortening of hippocampal formation (HF) in chronic schizophrenic patients have been demonstrated in our previous study. The purpose of the present study is to test if shortening of the HF occurs in schizophrenic patients suffering their initial psychotic episode. We performed contiguous, 1 mm thick, magnetic resonance imaging scans in 20 first-episode schizophrenic patients, 21 chronic schizophrenic patients, and 25 healthy subjects. Both groups of schizophrenic patients demonstrated significant shortening of the HF compared with normal controls (first-episode schizophrenia, 5.3%; chronic schizophrenia, 8.0%). However, the HF length was not significantly different between the first-episode and chronic schizophrenic patients. No significant correlation was seen between the HF length and the duration of illness in chronic schizophrenic patients. These results suggest that the HF shortening observed in schizophrenic patients may be genetic and/or developmental in origin.

Acute Disease↗

PubMed1989

A new bronchial asthma model using calcium ionophore A23187 in guinea pigs.

We attempted to develop a nonimmunologically induced asthma model using the calcium ionophore A23187. Inhalation of A23187 (0.001-0.005%) for 5 min in male Hartley guinea pigs caused a marked bronchoconstriction in a dose-dependent manner with negligible effect on systemic blood pressure. The A23187-induced bronchoconstriction was strongly inhibited by chlorpheniramine and FPL-55712. These results indicate that an asthma-like bronchoconstriction was induced by inhalation of A23187 in guinea pigs, and the main chemical mediators involved in this response would be histamine and peptidoleukotrienes.

Administration, Inhalation↗

PubMed1988

Alterations of accumbens neuronal activity in freely moving rats following methamphetamine.

Multiple unit activity in the nucleus accumbens, locomotor activity, and stereotyped behavior were simultaneously recorded in freely moving rats. An intraperitoneal injection of 1.5 mg/kg methamphetamine produced an increase in the firing rate while a decrease in the discharge rate occurred following an administration of 4.5 mg/kg methamphetamine. In addition, the unit activity was positively correlated with the locomotor activity and negatively correlated with the stereotypy score. These results suggest that accumbens neuronal activation during locomotor hyperactivity may partly depend on the feedback from locomotion.

Animals↗