PubMed Health⌕ Search

Biomedical subjects

A Uno

Publications and source records attributed to A Uno.

At least 19 recordsLinked to original sources
PubMed1999

Preattentive control of serial auditory processing in dichotic listening.

Dichotic listening performance was examined in an auditory selective attention task where subjects responded to occasional consonant-vowel (CV) or shaped broadband noise-burst (NB) targets in rapid serial auditory presentation (RASP). Trial types were randomized and included monaural CVs and NBs as well as dichotic CV-CV and CV-NB pairings. CVs were spoken by two different voices (male and female), and the two NB stimuli differed in their filter slopes at higher frequencies. The target was designated by stimulus category (/ba/, /da/, /ga/, or NB) and voice (e.g., "female /ba/"). Performance was compared for targets in the left and right ears on monaural and dichotic trials using accuracy and reaction time (RT) measures. Right ear advantages (REAs) were present for CV targets with either CV or NB distractors, but not for monaural CVs. The REA found for monaural NB targets was eliminated by CV distractors, yielding a left ear advantage (LEA) for the distractor effect of CVs on NB targets. The pattern of results suggests initial preprocessing of speech stimuli through phonetic feature analysis, followed by serial attentional processing of the objects in the auditory field. REAs are attributed to a rightward asymmetry in the preattentive control of auditory attention similar to that found in visual search.

Adult↗
PubMed1999

The long-term effect of bilateral inferior colliculus ablation on auditory brainstem response in awake cats.

In this study auditory brainstem responses (ABRs) were recorded repeatedly in three awake cats before and after bilateral aspiration of the inferior colliculi (ICs). All surgical procedures were performed under anaesthesia with Nembutal. Postoperative recordings were obtained 1 week, 3 months, 8 months and 13 months after bilateral aspiration of the ICs in order to study the long-term changes in ABRs. The P5 amplitude was markedly reduced only at 1 week after aspiration. P1 and P2 amplitudes were affected slightly at 3 months and 1 year, but those of P3 and P4 decreased significantly. After perfusion of these cats, histological examination of the brainstem revealed complete ablation of both ICs, neuronal loss in the nucleus of the lateral lemniscus and the superior olivary complex and preservation of the cochlear nucleus. Our results suggest that retrograde degeneration of neuronal cells of the brainstem, which project to the IC from the nucleus of the lateral lemniscus and superior olivary complex except the cochlear nucleus, affect the peak amplitudes of the ABR over the long-term.

Animals↗
PubMed1999

Age-related alteration of carbamazepine-serum protein binding in man.

To determine whether biological maturation influences the kinetics of carbamazepine-serum protein binding, the carbamazepine free fraction (%) was investigated in the serum of 66 patients, ranging from 4 to 83 years, with epilepsy or trigeminal neuralgia, treated with carbamazepine alone or carbamazepine in combination with phenytoin, phenobarbital, and/or valproic acid, over a relatively long period. Biochemical parameters such as levels of albumin and non-glycated albumin showed a significant relationship with carbamazepine free fraction (r = -0.521, P < 0.001 for albumin; r = -0.700, P < 0.001 for non-glycated albumin). Non-glycated albumin was more strongly correlated with carbamazepine free fraction. The biochemical parameters showed a significant relationship with age (r =-0.243, P < 0.1 for albumin; r =0.666, P < 0.001 for glycated albumin; r = -0.459, P < 0.001 for non-glycated albumin; r = 0.640, P < 0.001 for carbamazepine free fraction). Glycated albumin (%), non-glycated albumin and carbamazepine free fraction (%) were strongly correlated with age, whereas albumin showed only a weak correlation with age. To evaluate the effects of ageing on carbamazepine-serum protein binding, the patients were divided into three groups according to age: children, 4-15 years; adults, 16-64 years; elderly, 65-83 years. Albumin and non-glycated albumin were much lower, and glycated albumin (%) and carbamazepine free fraction (%) much higher in the elderly group than in the other two groups. The results of this study showed that the major ligand of carbamazepine in the serum was non-glycated albumin, which decreased with age. These observations suggested that in elderly patients, the elevation of free carbamazepine concentrations in the serum caused by reduced non-glycated albumin levels, induces increases in the sensitivity of the pharmacological effects of carbamazepine and the risk of drug interactions.

Adolescent↗
PubMed1999

[Neuropsychological approach to the learning disability: the correlation between neuropsychological findings and rCBF].

We investigated the relationship between a disorder of higher brain function and the area of reduced regional cerebral blood flow (rCBF) in learning disabled (LD) children. Subjects consisted of two LD children with a specific Kanji writing disorder, one with dyslexia and dysgraphia and two with a specific verbal semantic disorder. Neuropsychological assessment batteries were used to detect higher brain disorders, and single photon emission tomography to measure rCBF. We found that the area of reduced rCBF in LD children correspond to that in adults with an acquired brain damage showing similar symptoms. These results suggest that LD is caused by a localized brain dysfunction.

Adult↗
PubMed1999

[Mental health of families caring for people with developmental disabilities: the present situation and strategies for improvement].

The authors assessed the status of mental health of families caring for relatives with developmental disabilities and neurological diseases. They were caring for their children in good morale, however, "burnouts" or neurotic conditions were more frequent in these families than in the medical staffs, the latter being studied in our previous researches. Mentally healthy persons consulted their spouse about their children as well as other things, and received his/her assistance in daily care. Families helped by unrelated persons were in better mental state. Families who had utilized inpatient care before entering a school had higher expectations from their surroundings. Therefore, medical services should provide support to such families to help improve their mental health.

Adult↗
PubMed1999

[Deficit of language comprehension in a child with semantic-pragmatic disorder--dissociation between the phonemic and semantic processing abilities].

We studied the language comprehension deficit of a 11-year-old child with a semantic-pragmatic disorder. We used an original test battery using abstract nouns common to the tasks of repetition, reading aloud, auditory comprehension and comprehension of written words. Although he could repeat and read aloud words as good as normal controls, he could not choose correct pictures from semantically or phonemically resembling pictures by listening to or reading target words. This test demonstrated the dissociation between his phonemic and semantic processing abilities. An examination of the cerebral blood flow with SPECT suggested that the dysfunction of the left temporal lobe caused the deficit in language comprehension.

Brain↗
PubMed1998

Unilateral labyrinthectomy downregulates glutamate receptor delta-2 expression in the rat vestibulocerebellum.

The differential display method was applied to identify genes expression of which is altered in the flocculus after unilateral labyrinthectomy (UL). Total RNA from sham operated and labyrinthectomized rat flocculi was isolated, amplified by PCR using an arbitrary primer set and separated by electrophoresis on a polyacrylamide gel. PCR products the amounts of which were significantly lower in samples from labyrinthectomized animals than those from controls, were cut out of the gel and sequenced. One of the cDNA fragments showed 100% nucleotide sequence identity to the rat glutamate receptor (GluR) delta-2 subunit mRNA. In situ hybridization autoradiography showed that GluR delta-2 mRNA expression was intensely located to the floccular Purkinje cell layers. Furthermore, northern blot analysis showed that the delta-2 mRNA expression was decreased for at least two days after UL in accordance with diminishing UL-induced behavioral deficits. Therefore, it is suggested that the downregulation of delta-2 mRNA is involved in vestibular compensation. UL-induced spontaneous nystagmus (SN) was then examined in GluR delta-2 mutant mice. The frequency of SN in mutant mice was significantly more than that in wild mice until 12 h after UL. GluR delta-2-associated synaptic efficacy may be changed for the induction of vestibular compensation at the initial stage.

Animals↗
PubMed1998

Histaminergic influence on vestibular stimulation-induced locus coeruleus inhibition in rats.

In previous reports we have shown that caloric stimulation (CS) of the vestibular apparatus inhibits locus coeruleus (LC)-noradrenergic neuronal activity in urethane-anaesthetized rats. The present study examined the effect of neural histamine depletion by alpha-fluoromethylhistidine (alpha-FMH) on CS-induced LC inhibition. In alpha-FMH treated rats, LC neuronal inhibition caused by CS was still observed. This finding indicates that the central histaminergic neuron system does not participate in the CS-induced LC-noradrenergic inhibition. It is suggested that the noradrenergic neuron system is involved in the development of vestibulo-autonomic response, independent of the histaminergic neuron system.

Animals↗
PubMed1998

[Clinical significance of electrically evoked auditory brainstem response].

Electrically evoked auditory brainstem responses (EABR) were recorded in 31 postlingually deafened adults, who had recently received cochlear implants (mini-system, Cochlear Ltd). The wave consisted of three distinct positive peaks labeled P1, P2, and P3 with latency of 1.35 (+/- 0.14), 2.17 (+/- 0.18) and 4.08 (+/- 0.31) ms, respectively. The P3 threshold (EABR-T) and slope (EABR-S) were 0.9 (+/- 0.47) mA and 0.6 (+/- 0.28) muv/mA, respectively. The relationships between the EABR parameters (EABR T and -S of the P3 wave) and age, duration of deafness, promontory test and subjective response (T and C-level) were investigated. The scattergram showed a strong negative linear relationship between EABR-S and subjective T-level. This finding suggests that EABR-S is good measure of postoperative perception.

Adult↗
PubMed1998

[Clinical features in patients with delayed endolymphatic hydrops].

We report clinical features in patients with delayed endolymphatic hydrops (DEH) with juvenile unilateral deafness. Among 23 patients with DEH, 15 cases were diagnosed as ipsilateral DEH and 8 cases as contralateral DEH. The distribution of onset age showed two peaks at ages of < 30 years and > 40 years. In 80% of the ipsilateral DEH cases, the onset of episodic vertigo was at younger ages. On the other hand, in 75% of the contralateral DEH cases, the onset of fluctuation hearing loss of the contralateral ear was at older ages. Ispilateral DEH and Meniere's disease may show different pathophysiologies. The incidence of dominant negative summating potential in the better-hearing ear was 20% in the ispilateral DEH cases and 60% in the contralateral DEH cases. It is suggested that endolymphatic hydrops is in the better-hearing ear of contralateral DEH.

Adult↗
PubMed1997

Effects of glycosylation of hypoglycaemic drug binding to serum albumin.

The binding properties of hypoglycaemic drugs to glycosylated human serum albumin (G-HSA) were investigated using a fluorescence quenching method. Displacement patterns between tolbutamide and Sudlow's-site-specific drugs to G-HSA were also investigated. The order of the binding affinities of these drugs to HSA was glibenclamide > acetohexamide > tolbutamide > or = glicrazide > metfolmin. The order of the binding affinities were the same for G-HSA as for HSA. The ability of G-HSA to bind hypoglycaemic drugs, however, was much lower than that of HSA. Scatchard plots for the binding of tolbutamide to both albumins were biphasic. The glycosylation affected saturable binding sites (I and II), whereas it did not influence non-saturable binding sites. The displacement patterns of tolbutamide binding between both albumins were not affected in the presence of site-I- or III-specific drugs, whereas the relative binding of tolbutamide to site-II-specific drugs between the two albumins was remarkably changed. The glycosylation of HSA not only increases the unbound drug concentration but also changes the displacement pattern at site II. Our results suggest that the extensive glycosylation of plasma proteins in diabetic patients complicates drug-drug interactions beyond those seen in normal people.

Acetohexamide↗
PubMed1997

Effect of glycosylation on carbamazepine-serum protein binding in humans.

Effect of glycosylation on carbamazepine-serum protein binding was investigated in vitro using the serum from 24 diabetics and 10 healthy subjects, and in vivo using the serum from 49 patients receiving carbamazepine. In both binding studies, nonglycosylated albumin levels were strongly correlated with the carbamazepine free fraction (%). To evaluate the effect of glycosylation in vivo, the patients were divided into two groups according to glycosylated albumin levels (%): a healthy group (10-15) and a high group (15 and over). The high group had decreased nonglycosylated albumin levels and an increased carbamazepine free fraction. Our results suggest that one should not use total concentrations for the monitoring of serum carbamazepine concentrations, but free concentrations, especially in poorly controlled diabetics.

Adult↗
PubMed1997

Histamine release from the hypothalamus induced by gravity change in rats and space motion sickness.

Freely moving rats were exposed to 2 g hypergravity in an animal centrifuge device to produce motion sickness. Histamine release from the anterior hypothalamus of the rats was measured in vivo with a microdialysis technique. After a 2-h load of 2 g hypergravity, rats ate kaolin. Because pica, eating a nonnutritive substance such as kaolin, is a behavioral index of motion sickness in rats, this finding indicates that the rats suffered from motion sickness. During 2 g hypergravity for 2-h, histamine release from the hypothalamus was transiently increased. In contrast, neither the transient increase of histamine release nor the kaolin consumption were induced by 2 g hypergravity in bilaterally labyrinthectomized rats. Pretreatment with alpha-fluoromethylhistidine, an inhibitor of histamine-synthesizing enzyme, decreased both the basal and hypergravity-induced releases of histamine from the hypothalamus and suppressed the kaolin consumption induced by hypergravity. Taken together, these findings suggest that the vestibular information of changes in gravity activate the histaminergic neuron system, resulting in the development of motion sickness. More prolonged stimulation, a 4-h load of 2 g hypergravity, induced significant increase of kaolin consumption on postdays 1-3, though rats ate kaolin on postdays 1-2 after 2 g hypergravity for 2 h. During 2 g hypergravity for 4 h, the initial transient increase of histamine release was followed by the gradual increase of histamine release after the end of centrifugation. It is suggested that rats adapted to the hypergravity environment after centrifugation for 4 h, but not 2 h, so that the change in gravity from 2 g to 1 g became a provocative stimulation. We, therefore, concluded that motion sickness in rats induced by a negative change in gravity can be used as a simulation of space motion sickness, which is induced by exposure to microgravity. Histaminergic activation in the development of motion sickness induced by negative change in gravity might be an underlying mechanism of space motion sickness.

Animals↗
PubMed1997

Lipopolysaccharide and interleukin-1beta augmented histidine decarboxylase activity in cultured cells of the rat embryonic brain.

We investigated the effect of lipopolysaccharide (LPS) and various inflammatory cytokines on the histidine decarboxylase (HDC) activity in cultured cells of the rat embryonic brain. Histaminergic neuronal cell bodies were supposed to exist in cultured cells of the diencephalon but not in those of the cortex. The HDC activity was elevated by adding LPS and interleukin-1 beta (IL-1beta) but not by tumor necrosis factor-alpha (TNF-alpha) and IL-6 to the mixed primary cultures of diencephalon. In the adherent cell fraction of the cultured diencephalon cells, HDC activity was also enhanced by LPS and IL-1beta. In a similar manner, LPS augmented HDC activity in the mixed primary culture of cerebral cortical cells and in its adherent cell fraction. The effects of IL-1beta but not LPS in the mixed primary culture of diencephalon were canceled by a prior exposure to cytosine-beta-D-arabinofuranoside. The changes in HDC activity after exposure to LPS for 12 h were not accompanied by increased mRNA levels. In these cell cultures, mast cells were not detected by Alcian Blue staining. These results indicated the presence of the third type of HDC-bearing cell besides neurons and mast cells in the brain. The increase of HDC activity by IL-1beta might be due to cell proliferation.

Animals↗
PubMed1997

Auditory evoked responses under total spinal anesthesia in rats.

In order to investigate the function of the auditory pathway from the cochlea to the brain stem under total spinal anesthesia, the auditory brain stem response (ABR), compound action potential of the cochlear nerve (CAP), and cochlear microphonics (CM) were simultaneously recorded in rats. Total spinal anesthesia was induced by infusion of 2% lidocaine hydrochloride at a constant rate of 0.10 mL/min into the cerebrospinal fluid through the rats' skulls. The ABR completely disappeared within 1.5 to 4 minutes. After cessation of the injection, the ABR reappeared, starting from wave I and progressing through waves II and III to wave IV. The latency change of the CAP throughout the recording period was quite similar to that of wave I of the ABR. A reduction in amplitude of the CM was observed, but the CM did not disappear during the recording period. Disappearance of the ABR was due, not to loss of cochlear function, but to anesthetic effects on the acoustic nerve and the brain stem. Monitoring of the ABR provided information on the level of neural activity in the brain stem under total spinal anesthesia.

Action Potentials↗