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Biomedical subjects

H Wada

Publications and source records attributed to H Wada.

At least 1,225 records · Page 68Linked to original sources
PubMedDate not supplied

Histaminergic neuron system in the brain: distribution and possible functions.

Recent immunocytochemical studies have identified the histaminergic neuron system in the brain. In the rat brain, histaminergic neuronal cell bodies are located in the tuberomammillary nucleus in the posterior hypothalamus, while histaminergic fibers are distributed in almost all regions of the brain. Similar distributions of histaminergic neuronal cell bodies and fibers have been reported in the brains of other mammals and nonmammalian vertebrates. As expected from the widespread distributions of the efferent fibers, the central histaminergic neuron system seems to be involved in multiple functions in the brain. The results of intracerebral injection of histamine and administration of alpha-fluoromethylhistidine (FMH), which depletes brain histamine level, suggest that the central histaminergic system may modulate feeding, drinking and sexual behaviors, sleep-wakefulness and circadian rhythm, neuroendocrine and cardiovascular controls and thermoregulation.

Animals↗
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Preventive effects of dexamethasone on hypoxic-ischemic brain damage in the neonatal rat.

To clarify the preventive effects of glucocorticoid on perinatal hypoxic-ischemic (HI) brain damage, an experiment was carried out on 4-day-old rats pretreated for 4 consecutive days with 3 different regimens; namely, a low dose dexamethasone (Dex) (0.1 mg/kg/day), a high dose Dex (0.5mg/kg/day), and a saline administration. On the 7th postnatal day, after ligation of the left common carotid artery, the rats were exposed to 8% oxygen and decapitated on the 10th, 14th, 21st and 28th postnatal days. Ligated side brain damage was observed in 75, 7 and 3% of the rats in the saline, low and high dose Dex groups, respectively. However, a high mortality rate (42%) was noted in the high dose Dex group. The cumulative number of animals with poor outcome (death or brain damage) was 49 (80%), 13 (33%) and 24 (44%) in the saline, low and high dose Dex groups, respectively. On the 10th and 14th postnatal days, the rats in both the Dex groups showed delayed neuronal maturation and myelination in the non-ligated side motor cortex, however, these maturational differences disappeared on the 21st postnatal days. Otherwise, the number of cortical cells in both the Dex groups were significantly lower than that in the saline group on the 28th postnatal days (P < 0.05 in each). These findings suggest that the pretreatment with Dex protects the developing brain from HI injury through the suppression of the neuronal maturation. However, a decreased number of cortical cells may give rise to psychomotor retardation later.

Animals↗
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Severe neonatal nemaline myopathy with delayed maturation of muscle.

A Japanese infant with a severe neonatal form of nemaline myopathy showed features of muscle immaturity as well as rods in the biopsied quadriceps femoris muscle, and involvement of diaphragm was first confirmed at autopsy. The biopsied muscle showed numerous rods in 80% of muscle fibers, and an increased number of type 2C fibers (23.2%). Electron microscopic findings were characterized by the presence of many small, immature round fibers with central nuclei and sparse myofibrils, and an increased number of satellite cells in close association with the small muscle fibers, as well as numerous rod structures. These microscopic and electron microscopic findings are interpreted as immature muscle fibers. Maturational delay or arrest implies deprivation of a development promoting factor such as a neuronal signal. Severe involvement with numerous rods was demonstrated in both diaphragm and intercostal muscles at the time of the postmortem examination, compatible with the patient's respiratory failure.

Fatal Outcome↗
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Vascular involvement in benign infantile mitochondrial myopathy caused by reversible cytochrome c oxidase deficiency.

A 1-month-old Japanese girl had profound generalized weakness, hypotonia, and severe lactic acidosis. The infant improved gradually: she held her head at 9 months, learned to walk by 15 months. At the first muscle biopsy at 11 weeks of age, the specimen was characterized by numerous ragged-red fibers and decreased enzyme activity on cytochrome c oxidase (COX) staining. Electron microscopic findings were characterized by the presence of excessive abnormal mitochondria not only in skeletal muscle fibers but also in blood vessels. Vascular abnormalities consisted of an increased number of enlarged mitochondria in endothelial and smooth muscle cells of small arteries. Biochemical analysis showed an isolated defect of COX activity, which was only 16% of the mean control level. At the second biopsy at 44 months of age, the COX activity had increased to normal in the entire specimen. On electron microscopy, the abnormal mitochondria present on the first biopsy specimen had disappeared both in muscle fibers and blood vessels; nearly all mitochondria were morphologically normal at the second biopsy. Now at 5 years of age she can run and does not show muscle weakness. We report reversibility of abnormal mitochondria with age not only in skeletal muscle fibers but also in blood vessels in a patient, who had reversible COX deficiency with a benign clinical course.

Arteries↗
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Repeated toluene exposure and changes of response latency in shock avoidance learning.

Behavioral effects of repeated exposure to toluene were investigated. After 1, 3, and 6 weeks exposure to toluene at 1000 and 2000 ppm, all rats received shock avoidance training. Toluene-exposed rats could acquire shock avoidance learning and there was no significant difference between exposed rats and control rats. Analyzing response latencies (RLs) of avoidance responses, control rats shifted them to a longer RL and at last they learned to perform avoidance responses with specific RLs (3-4 sec). However, rats exposed to 1000 ppm toluene for 1 week and to 2000 ppm toluene for 1 week and 3 weeks, did not learn to respond with specific RLs. Rats exposed to 1000 ppm and 2000 ppm toluene for 6 weeks did not shift to longer RLs. It was suggested that repeated exposure to toluene vapor ranging up to 2000 ppm had no influence on the acquisition of shock avoidance learning, but caused some functional impairments of higher nervous functions.

Animals↗
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Single toluene exposure and changes of response latency in shock avoidance performance.

The behavioral effects of a single exposure to toluene were investigated using shock avoidance performance. Rats were exposed to 2000, 4000, 6000, and 8000 ppm toluene vapor for 4 hr after they acquired shock avoidance learning. Then the effects of toluene on avoidance performance, locomotor activity, and response latencies (RLs) were simultaneously examined for 3 days. Shock avoidance responses were significantly decreased at concentrations of 4000, 6000, and 8000 ppm, but recovered 3-6 hr after the cessation of exposure. The 2000 ppm exposure had no effect on these responses. Locomotor activity was transiently increased at concentrations of 2000 ppm and 4000 ppm, but recovered after 6 hr. Both 6000 ppm and 8000 ppm exposure at first decreased locomotor activity but later increased it. There were biphasic effects, inhibition and excitation, on locomotor activity, and it took 1 day to recover from them. Response latencies were shortened at concentrations of 2000, 6000, and 8000 ppm. That was due to hyperactivity. However, 4000 ppm toluene exposure induced the prolongation of RLs, although ataxia or narcosis were not observed. It was suggested that certain higher nervous functions in the central nervous system (CNS) which controlled timing behavior might be confused.

Animals↗
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Effects of endoscopic injection sclerotherapy on portal hypertensive gastropathy: a prospective study.

The effect of endoscopic injection sclerotherapy (EIS) for esophageal varices on portal hypertensive gastropathy (PHG) was investigated in 137 patients who underwent EIS from July 1987 to March 1990. Two groups, PHG(+) (N = 35) and PHG(-) (N = 102) were distinguished by endoscopic findings obtained before EIS. PHG was classified into four grades by endoscopy scored as 0, 1, 2, or 3. The PHG score significantly worsened after EIS (p < 0.01), and PHG became worse 6 to 9 months after the eradication of varices followed by gradual improvement. Recurrent small veins, which required additional EIS, appeared more frequently in the PHG(+) group (p < 0.05). New gastric varices appeared or gastric varices enlarged after EIS more frequently in the PHG(+) group (7 patients, 20.0%) than in the PHG(-) group (12 patients, 11.8%), but this was not statistically significant. Thus, frequent endoscopy after EIS is needed with special attention directed to development of PHG and gastric varices, especially for patients with PHG prior to treatment.

Esophageal and Gastric Varices↗
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Analysis of second-order kernel response components of multifocal electroretinograms elicited from normal subjects.

PURPOSE: It has been reported that the second-order kernel response components of multifocal electroretinograms (mERGs) reflect the electrical activity of the inner retinal layers. In this study, we have investigated whether the amplitudes of the second-order kernel response components correlate with the spatial distribution of human retinal ganglion cells. METHODS: Multifocal electroretinograms were recorded using the Veris III system from 5 healthy subjects with different stimulus and recording parameters. The mERGs were analyzed using the Veris Science software programs. The stimuli consisted of densely arranged arrays of 103, 61, 37 or 19 hexagonal elements. Four minutes were required to record one set of mERG responses using 8 sessions, and 8 minutes using 16 sessions. The second-order kernel response components were extracted and analyzed using the Veris Science program. RESULTS: The signal-to-noise ratio of the first-order kernel response components was improved considerably by the summation of the nine reproducible responses from the same subject but the second-order kernel response components were not. The summation of the nine reproducible responses was insufficient to identify an array of the second-order kernel response components. Both the first- and second-order kernel response components were larger when fewer hexagonal elements were used. There was no significant difference in the individual responses between the 4-minute and the 8-minute recordings. A response density analysis revealed a weak correlation between the amplitude distribution of the second-order kernel response components and the spatial distribution of human retinal ganglion cells. CONCLUSIONS: The distribution of the amplitudes of the second-order kernel response components of the mERGs elicited from normal subjects did not correlate with the distribution of human ganglion cells. This suggests that the theory that second-order kernel response components arise from the activity of retinal ganglion cells should be reconsidered.

Adult↗
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Toluene and temporal discrimination behavior in the rat.

Fifteen rats were trained to perform a temporal discrimination between two signal durations using a standard Skinner box with two levers. When a 2-s tone signal was presented, rats were required to press one lever ("SHORT" response), and when an 8-s tone signal was presented, they were required to press another lever ("LONG" response). Then five intermediate tone signals were introduced and all signals were pseudorandomly presented. In the case of 2- and 8-s signals, rats could gain a food reward if they pressed the correct lever. When five intermediate signals were presented, neither response was reinforced. After stable performance was established, percentages of "LONG" responses to the seven signals were calculated. The percentages increased as a function of signal durations. Then three dosages of toluene were intraperitoneally administered. Treatment with 100 mg/kg toluene increased the gradient of the psychophysical function between signal durations and percentages of "LONG" responses, and accuracy of performance improved. There was no clear change in the rats injected with 200 mg/kg. However, 400 mg/kg toluene decreased the gradient. The temporal gradient reflects discriminability of signal durations. Therefore, it was proposed that treatment with 100 mg/kg toluene improved discriminability and enhanced accuracy of temporal discrimination in the rats. The treatment with 400 mg/kg toluene reduced the accuracy of temporal discrimination.

Animals↗
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Toluene and temporal discrimination in rats: effects on accuracy, discriminability, and time estimation.

Thirty-five rats acquired a temporal discrimination of seven signal durations in an operant chamber with two levers. If a 2-s or an 8-s tone signal was presented, rats were required to press one lever ("short" response) or the other lever ("long" response) to be reinforced, respectively. Neither response was reinforced when five intermediate signals were presented. Percentages of a long response in each of the seven signals were calculated and the psychophysical function between signal durations and long response percentages was obtained. Intraperitoneal injections of 50 mg/kg and 100 mg/kg toluene steepened a gradient of the psychophysical function and elevated correct responses in 2-s and 8-s signals. The function showed lower difference limen and Weber fraction. Accuracy and discriminability of temporal discrimination were enhanced. However, 400 mg/kg and 600 mg/kg toluene resulted in a shallower gradient and reduced correct responses. Higher difference limen and Weber fraction were also obtained. Accuracy and discriminability deteriorated and, in particular, behavioral depression was observed for 600 mg/kg toluene. The point of indifference was changed and dose-related overestimation or underestimation of time were suggested to occur. Blood toluene levels were reported to be 11-18 microg/ml for 50-100 mg/kg toluene and 47-73 microg/ml for 400-600 mg/kg toluene. It is speculated that temporal discrimination was sharpened by 10-20 microg/ml toluene in blood and disrupted by 50-70 microg/ml toluene in blood.

Animals↗
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A case of IgG4-related autoimmune disease with multiple organ involvement.

A 52-year-old male was admitted with autoimmune pancreatitis (AIP), showing mononuclear cell infiltration in both the pancreas and salivary glands with both normal sialography and anti-SS-A/SS-B antibodies. Although the AIP improved with glucocorticoid treatment, subsequent abdominal computed tomography (CT) revealed a nodular shadow in the bilateral kidneys, which was confirmed as interstitial nephritis by renal biopsy. The patient's serum immunoglobulin G4 (IgG4) level was 10 times higher than the upper limit of the normal range. IgG4-positive mononuclear cell infiltration was detected in the salivary gland, pancreas, and kidney. A new entity proposed as 'IgG4-related autoimmune disease' was considered.

Autoimmune Diseases↗
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Spinal canal involvement in infantile myofibromatosis: case report and review of the literature.

PURPOSE: An unusual case of infantile myofibromatosis with spinal canal involvement is reported and the literature is reviewed. PATIENT AND METHODS: A female neonate had bladder and bowel dysfunction and paresis of the lower extremities. RESULTS: Intrapelvic and paravertebral masses with extension into the spinal canal were detected by imaging studies. In addition, radiologic examination showed multiple metaphyseal radiolucent lesions of the long bones and pathologic fracture of the left femur. The histopathologic diagnosis of the paravertebral tumor and bone lesions was infantile myofibromatosis. Surgical resection of the paravertebral and intrapelvic masses was performed to improve her neurologic impairments. Paresis of the lower limbs gradually improved, whereas bladder and bowel dysfunction remained unchanged. CONCLUSIONS: Only six cases of infantile myofibromatosis associated with spinal canal involvement have been reported. Three patients with flaccid paresis of extremities and respiratory distress died in the newborn period. The other three patients showed improvement of the paresis. The prognosis of infantile myofibromatosis without visceral complication is generally good, but neurologic impairment may occur at birth if the spinal cord is compressed.

Bone Neoplasms↗
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Comparative effects of 5% ethanolamine oleate versus 5% sodium morrhuate for sclerotherapy of oesophageal varices.

Forty-five cirrhotic patients with oesophageal varices were randomized to receive endoscopic injection sclerotherapy with either 5% ethanolamine oleate (EO), or 5% sodium morrhuate (SM). In the EO group, there was a statistically significant higher rate of disappearance of red colour signs on the varices a week after the initial session of sclerotherapy than in the SM group (91.3% vs 45.5%, P less than 0.05). A jet-like bleeding from injection sites at the second session of sclerotherapy occurred in three patients in the SM group and they experienced blurred vision. There was no such occurrence in the EO group. Oesophageal bleeding requiring blood transfusion during the course of repeated sclerotherapy occurred only in the SM group (five patients): bleeding was from a partly thrombosed varix and in four was from oesophageal ulcers. We found that EO administered intravariceally is more efficacious than SM for sclerotherapy of oesophageal varices.

Esophageal and Gastric Varices↗
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Effect of irregularities in basilar membrane impedance on TEOAEs: theoretical considerations.

Transiently evoked otoacoustic emissions (TEOAEs) are believed to be attributed to the presence of impedance discontinuities on the basilar membrane in the cochlea. However, the generation mechanism of TEOAEs has not been clarified. In this study, using the mathematical model of a cochlea, which has the impedance discontinuities on the basilar membrane, TEOAEs were simulated. The results reveal that the TEOAEs are produced by not only the active process associated with the outer hair cell motility, but also the presence of impedance discontinuities at a site of the basilar membrane whose characteristic frequency is close to the stimulus frequency. Therefore, it may be said that the TEOAEs in response to a tone burst stimulus reflect the condition at the specific point of the cochlea.

Basilar Membrane↗
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Risk factors of aspiration pneumonia in Alzheimer's disease patients.

BACKGROUND: Pneumonia is the reported cause of death of a high proportion of Alzheimer's disease (AD) patients. OBJECTIVES: This study assessed swallowing function to explore the potential risk factors of aspiration pneumonia in AD patients. METHODS: Data were gathered on 121 AD patients (mean age 78.2, SD 7.5, male/female ratio = 48/73) treated in two psychiatric hospitals. Multiple logistic regression analysis was used to estimate odds ratios for the risk of aspiration pneumonia. The following risk factors were considered: age, severity of dementia, silent brain infarction (SBI) in the basel ganglia, use of psychotropic drugs (neuroleptics and benzodiazepines), and gender. The latency time of the swallowing reflex was analyzed (1) among groups based on the severity of dementia; (2) between groups with and without SBI in the basal ganglia; (3) before and after the use of psychotropic drugs in the group without SBI in the basal ganglia, and (4) between males and females. RESULTS: Aspiration pneumonia in ambulatory AD patients was significantly and independently associated with severe dementia, presence of SBI in the basal ganglia, intake of neuroleptics, and the male gender. The mean latency of the swallowing reflex in the severe AD group was significantly longer compared to that in the mild-to-moderate AD group. The mean latency of the swallowing reflex after the intake of neuroleptics was significantly prolonged compared to that obtained before any neuroleptic intake, whereas there was no significant difference in the mean latency of the swallowing reflex before and after benzodiazepine intake. CONCLUSION: We recommend the use of the smallest efficacious dosage of neuroleptics especially in treating severely demented AD patients with basal-ganglia infarction. As soon as the behavioral and psychiatric problems are resolved, drug tapering or discontinuation should be considered in order to prevent life-threatening aspiration pneumonia.

Aged↗
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Involvement of IL-18 and soluble fas in patients with postoperative hepatic failure.

We measured the levels of tumor necrosis factor alpha (TNF-alpha), interleukins (IL)-6 and -18, and soluble Fas (sFas) in 11 patients with postoperative hepatic failure and assessed whether IL-18-mediated apoptosis is involved in the onset of liver dysfunction. The serum TNF-alpha, IL-18, and sFas levels were significantly higher in patients with sepsis as a complication than in those without sepsis. The TNF-alpha and IL-18 levels were significantly higher in nonsurvivors than in survivors. Significant correlations were observed between TNF-alpha and IL-6, between TNF-alpha and IL-18, and between TNF-alpha and sFas levels. These results showed that Fas-mediated hepatocyte apoptosis functions as an important mechanism responsible for the onset of postoperative hepatic failure in humans. They especially suggested that IL-18 and TNF-alpha function both as apoptosis-promoting factors and as apoptosis-inhibiting factors, depending on the conditions to which hepatocytes are subjected.

Aged↗