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Biomedical subjects

R Tamura

Publications and source records attributed to R Tamura.

At least 55 records · Page 3Linked to original sources
PubMed1998

Use of transvaginal color Doppler ultrasound in the diagnosis of ovarian bleeding: a report of 10 cases.

Ten patients with ovarian bleeding, who were surgically treated, had been preoperatively evaluated using transvaginal color Doppler ultrasound. The blood-flow velocity waveforms of the bleeding also were analyzed. The bleeding artery of the ovary was clearly detected in 9 of 10 (90%) patients by transvaginal color Doppler ultrasound and was later confirmed by either a laparotomy or laparoscopic surgery. Either a corpus luteum cyst or a ruptured corpus luteum was associated with the bleeding in the 9 of the 10 patients. The resistance-index value in each bleeding artery examined in the 9 cases was relatively low, ranging from 0.46 to 0.59 (mean: 0.51). Based on our findings, transvaginal color Doppler ultrasound is useful for preoperatively detecting bleeding arteries in clinically severe cases of ovarian bleeding.

Adult↗
PubMed1998

Gustatory and multimodal neuronal responses in the amygdala during licking and discrimination of sensory stimuli in awake rats.

The amygdala (AM) receives information from various sensory modalities via the neocortex and directly from the thalamus and brain stem and plays an important role in ingestive behaviors. In the present study, neuronal activity was recorded in the AM and amygdalostriatal transition area of rats during discrimination of conditioned sensory stimuli and ingestion of sapid solutions. Of the 420 responsive neurons, 227 responded exclusively to one sensory modality, 120 responded to two or more modalities, and the remaining 73 could not be classified. Among the responsive neurons, 108 responded to oral-sensory stimulation (oral-sensory neurons). In detailed analyses of 84 of these oral-sensory neurons, 24 were classified as taste responsive and were located mainly in the central nucleus of the AM. The other 60 oral-sensory neurons were classified as nontaste oral-sensory neurons and were distributed widely throughout the AM. Both the taste and nontaste oral-sensory neurons also responded to other sensory stimuli. Of the 24 taste neurons, 21 were tested at least with four standard taste solutions. On the basis of the magnitudes of their responses to these sapid stimuli, the taste neurons were classified as follows: seven sucrose-best, four NaCl-best, three citric acid-best, and six quinine HCl-best. The remaining cell responded significantly only to lysine HCl and monosodium glutamate. Multivariate analyses of these 21 taste neurons suggested that, in the AM, taste quality was processed based on palatability. Taken with previous lesion studies, the present results suggest that the AM plays a role in the evaluation of taste palatability and in the association of taste stimuli with other sensory stimuli.

Acoustic Stimulation↗
PubMed1998

Real-time evaluation of the effectiveness of microwave coagulation therapy for hepatocellular carcinoma using color Doppler imaging.

Percutaneous microwave coagulation therapy (PMCT) is a new technique for the treatment of hepatocellular carcinoma (HCC). However, it is difficult to distinguish those lesions in which necrosis has been induced from the viable residual lesions during the procedure, because the margin of the tumor becomes unclear during PMCT. We determined the area of necrotic lesions during the procedure using color Doppler imaging. PMCT was performed on 10 patients (17 lesions) with recurrent HCC. The electrode of the microwave delivery system was moved around the tumor and the surrounding area until color mosaic images disappeared from the entire area of the tumor. The areas in which necrotic tissue was indicated by color Doppler imaging were later confirmed by other modalities such as angiography or contrast-enhanced computed tomography. This leads us to believe that real-time, effective evaluation of PMCT is possible with color Doppler imaging.

Aged↗
PubMed1998

[Antiphospholipid antibodies in the elderly patients with ischemic stroke].

The importance of antiphospholipid antibodies as a cause of ischemic stroke in young adults is well demonstrated in the previous studies, but the relationship between the elderly patients with ischemic stroke and antiphospholipid antibodies is not defined. The frequency of positivity for antiphospholipid antibodies was 5.4% (6 out of 112 elderly patients with ischemic stroke), and much higher than that of the elderly healthy individuals (none of 108 individuals) (p < 0.001). Equal numbers of stroke patients with or without antiphospholipid antibodies had other stroke risk factors. The clinical features of the elderly patients with ischemic stroke, who were positive for antiphospholipid antibodies, presented recurrent and multiple infarct dementia, and had thromboses of the other organs. The hemostatic state of the patients with positive antiphospholipid antibodies revealed, in particular, increased intravascular coagulation. Antithrombotic treatment with warfarin at high international normalized ratios (INRs: 1.47-2.80) were effective comparing with antiplatelet treatment with ticlopidine alone in preventing further thromboembolic events.

Aged↗
PubMed1997

Relationship between change of movement direction and activity of hippocampal place cells.

Hippocampal neurons which increase their activity when the rat passes through a certain position in the environment are called place cells. This paper describes the relationship between their temporal firing patterns and the behavior of the rat with the aim of characterizing the information they encode. The place field was identified in a circular open field during locomotion rewarded by intracranial self-stimulation of lateral hypothalamus. Detailed analysis of temporal firing patterns shows a correlation between changes in the orientation of movement trajectory and occurrence of the last firing of the burst trains emitted during passage of the animal through the place field. This suggests that some hippocampal neurons may encode the spatial information about the orientation changes in the place field.

Animals↗
PubMed1997

Calcitonin gene-related peptide- and substance P-like immunoreactive fibers in the spermatic nerve and testis of the dog.

In order to determine if calcitonin gene-related peptide (CGRP) and substance P (SP) coexist in peripheral spermatic nerve fibers, we carried out a double-staining immunofluorescence study using confocal microscopy and fluorescence microscopy. CGRP- and SP-like immunoreactivity (LI) coexisted in the spermatic nerve trunk and in the single fibers running along the surface of the testis. The great majority of the SP-containing fibers also held CGRP-LI, although some fibers contained CGRP-LI without SP-LI. These observations are consistent with previous observations on testicular dorsal root ganglion neurons. Additionally, we carried out an immunogold silver staining for CGRP and found CGRP-containing nerve bundles, single nerve fibers and their nerve terminals. Some CGRP-containing nerve terminals were located very superficially in the tunica albuginea (<5 microm from the surface).

Animals↗
PubMed1997

The relationship between monkey hippocampus place-related neural activity and action in space.

To solve complex spatial problems like visual scanning and spatial navigation, animals must explore and actively sense an array of environmental stimuli. Recent studies have led to an agreement that the hippocampal formation (HF) is essential to the internal representation of spatial relation in animals. In the present study, neural activity was recorded from the HF of three monkeys, which steered a cab to various locations by pressing the appropriate bars (spatial moving task). Place-related activity of most HF neurons persisted even if the direction the monkey faced was rotated during the task. However, when the experimenter, rather than the monkey, controlled the device, the place-related neural activity of most HF neurons turned out to be obscure. The results suggest that the HF represents space effectively in situations in which the animal acts in space.

Animals↗
PubMed1997

Septal neuronal responses related to spatial representation in monkeys.

Neuronal activity in the monkey septal nuclei was recorded during performance of a place-dependent go/no-go task in which reward contingencies of the objects were variable with reference to the spatial location of a monkey's cab in one of four places in an experimental room. Of 430 septal neurons recorded, 58 responded differentially to views outside the cab at the four locations of the monkey (place-differential neurons). To investigate the possibility that an ensemble of place-differential neurons represents a space by encoding different scenes (views), responses of the 58 place-differential neurons were analyzed by multidimensional scaling (MDS). The MDS transformed relationships among the four places, expressed as correlation coefficients between all possible pairs of two places based on the 58 place-differential responses, into geometrical relationships in a two-dimensional virtual space. The four places distributed at relative positions in a two-dimensional virtual space derived from the MDS were similar to those in the real experimental room. Furthermore, these correlation coefficients derived from 58 place-differential responses significantly and negatively correlated to behavioral performance in the discrimination of the four places. The results suggest that the ensemble of place-differential responses in the septal nuclei may predict behavioral performance to discriminate places and may represent a space based on the scenes viewed from different locations.

Acoustic Stimulation↗
PubMed1997

Motivation-related neuronal activity in the object discrimination task in monkey septal nuclei.

Septal nuclei are suggested to work as an interface between the hippocampal formation, involved in higher cognitive functions, and the hypothalamus, involved in motivational behaviors such as feeding, drinking, and intracranial self-stimulation. In the present study, to elucidate a role of the septal nuclei in motivational behaviors, single neuron activity was recorded from water- and food-deprived monkeys during discrimination of objects associated with juice, and during ingestion of juice. Of 349 neurons recorded from two monkeys, 67 responded in the ingestion phase of the object discrimination task. Of these 67 neurons, 31 were further tested with the noncontingent liquid (juice or water) test in which liquid was provided until the animals became satiated. These 31 septal neurons were classified into two groups: type I neurons (n = 10) responded to juice ingestion with inhibition, and type II neurons (n = 21) responded with excitation. The spontaneous firing rates of the type I neurons were higher in the deprived condition and decreased as the animal became satiated by intake of liquid. Nine type II neurons responded to the sight of a white object associated with juice as well as ingestion of juice. The response magnitudes of the type II neurons to both the sight of the white object and ingestion of juice also decreased by satiation. However, spontaneous firing rates of the type II neurons did not change. These activity changes of both type I and II neurons were well correlated with changes in motivational state of the monkey estimated by the behavioral test. The results suggest that the activity of type I neurons reflects thirst or hunger drive levels, and that responses of type II neurons are related to reward perception. These type I and II neurons were located mainly in the anterior part of the septal nuclei. Results of the present study suggest, along with previous lesion and anatomical studies, that the septal nuclei exert a powerful influence on the motivational/drive systems through the projection to the hypothalamus.

Animals↗
PubMed1997

Effects of lentinan on abnormal ingestive behaviors induced by tumor necrosis factor.

Lentinan (LNT), a beta-glucan derived from Lentinus edodes (Berk.) Sign., is known to work positively against cachexia in patients with malignant tumors. Because the cachectin/tumor necrosis factor (TNF) is supposed to be one of the factors that mediate cancer cachexia, we tested the effects of LNT on TNF-induced cachexia in rats. First, we analyzed in detail the cachectic actions of TNF (0.2 mg/kg/day, 5 days, IV) on food and water intake, body weight, and locomotor activity. The day after the first administration of TNF (acute phase), food and water intake, as well as body weight, of all rats decreased. However, over the next few days of treatment (chronic phase), the rats gradually developed a tolerance to the cachectic actions of TNF. Specifically, after the third administration, the rats treated with TNF had a higher amount of water intake than the control rats. This was mainly due to an increase in daytime water intake. We also analyzed the effects of LNT (0.1 or 1.0 mg/kg, twice/wk. IV) on TNF-induced cachexia, and compared the data with those from the rats treated with TNF alone. The higher dosage of LNT significantly suppressed TNF-induced daytime polydipsia and increased the amount of nighttime water intake, as well as the meal size of nighttime food intake. These results suggest that LNT partially normalizes TNF-induced cachexia in rats.

Animals↗
PubMed1997

Effects of repeated cold stress on feeding, avoidance behavior, and pain-related nerve fiber activity.

The specific alternation of rhythm in temperature (SART), which is defined as rapid and frequent changes in the environmental temperature several times within the course of a day, produces abnormalities in behavior such as hyperphagia and in sensory sensation such as hyperalgesia. As the first step toward understanding the mechanisms of these abnormalities, we studied the effects or SART stress on ingestive behavior. During the light and dark phases, the animals' food intake increased, but their body weight gain decreased. In addition, diurnal variation in body weight also decreased. Next, we examined the behavioral and electrophysiological effects of SART stress on avoidance behavior by studying the rat's avoidance of a noxious stimulus in the form of a footshock. The rats demonstrated hyperreactivity; the delay in escaping the footshock was decreased by SART stress. The excitability of C-fiber activity, which responds to mechanical and thermal stimuli to a single saphenous nerve, was not changed by SART stress. This suggests that the hyperreactivity in footshock avoidance and the hyperalgesia in pain response induced by SART stress are based on excessive emotionality.

Animals↗
PubMed1997

Sonodynamic changes after transcatheter arterial embolization in a vaginal hemangioma: case report.

A 36-year-old pregnant woman with a rapidly growing hemangioma in the vagina was treated by transcatheter arterial embolization after delivery. Blood flow characteristics within the tumor were evaluated using transvaginal color Doppler ultrasound both before and after the embolization. The vascular resistance in the tumor vessels within the vaginal hemangioma was observed to be significantly decreased; the tumor reduced in volume following this non-surgical treatment.

Adult↗
PubMed1997

Repeated sodium depletion affects gustatory neural responses in the nucleus of the solitary tract of rats.

Furosemide sodium depletions were induced repeatedly to determine the effects on gustatory neural responses in the nucleus of the solitary tract (NST) of chronically prepared, but lightly anesthetized, rats. Sodium-replete and sodium-deplete conditions were alternated four times in each rat. When rats were under depleted conditions, the responses to NaCl were significantly greater than in sodium-replete conditions. This effect was attributable primarily to an increase in the magnitude of response of those neurons that responded better to NaCl than to the other standard stimuli (sucrose, citric acid, and quinine hydrochloride). In addition, the largest change in responsiveness of the NaCl-best neurons occurred during the third and fourth sodium depletions. These results are essentially opposite to those reported for NST neurons when sodium appetite is induced by dietary sodium restriction. This suggests that the coding of intensity in the gustatory system is dependent not only on the animal's deprivation condition, but also the method through which the deprivation is produced.

Animals↗
PubMed1996

Localization of heparin-binding epidermal growth factor-like growth factor in human coronary arteries. Possible roles of HB-EGF in the formation of coronary atherosclerosis.

BACKGROUND: Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) is a newly identified member of the EGF family. Our previous in vitro studies showed that HB-EGF is a potent mitogen and chemoattractant for vascular smooth muscle cells (SMCs), suggesting the role of HB-EGF in the pathogenesis of atherosclerosis. The purposes of the present study were to investigate the localization of HB-EGF in both normal and atherosclerotic human coronary arteries and to elucidate the possible roles of this growth factor in the formation of atherosclerotic lesions. METHODS AND RESULTS: The immunohistochemical localization of HB-EGF, SMCs, macrophages, and EGF receptors (EGFRs) was examined in human coronary arteries obtained at autopsy. The medial SMCs of coronary arteries in neonates, infants, and children consistently synthesized HB-EGF protein. In normal adults, however, the relative number of HB-EGF-positive medial SMCs decreased gradually with age after about 30 years of age. In nonatherosclerotic coronary arteries with diffuse intimal thickening, SMCs of the intima, especially those located in the area of the medial side of the intima, were strongly positive for HB-EGF protein. In atherosclerotic plaques of coronary arteries with eccentric intimal thickening, both SMCs and macrophages in and around the core lesions, in addition to the intimal and medial SMCs located adjacent to the plaque, produced HB-EGF protein. A strong immunostaining of EGFRs was observed in these SMCs, suggesting a close association of HB-EGF and EGFR expression. CONCLUSIONS: These data suggest that HB-EGF might play important roles in the migration of SMCs from the media to the intima, the proliferation of intimal SMCs, and the interaction between SMCs and macrophages in the process of coronary atherogenesis.

Adult↗
PubMed1996

Segmental distribution of afferent neurons innervating the canine testis.

To clarify the afferent innervation of the canine scrotal contents, retrograde labeling of neurons in the dorsal root ganglia (DRG) has been carried out using two methods: (1) horseradish peroxidase (HRP) injection into the surface of the testis and epididymis; and (2) exposure of the superior spermatic nerve to a fluorescent dye (Fast blue; FB). Injections of HRP resulted in labeling of DRG cells located predominantly from T10 to L4 (87%) and, to a lesser extent, at S1-S3 (13%). Transection of the vas deferens previous to testicular injections eliminated labeling in the S1-S3 DRG, but not at thoracolumbar levels. These findings indicated that primary afferent fibers of the testis and epididymis project mainly to the DRG at higher than L4 through the superior spermatic nerve, but an additional population of the fibers also projects the sacral level through the inferior spermatic nerve. Exposure of the superior spermatic nerve to FB resulted in a similar distribution of labeled cells as compared with testicular injections of HRP after vasectomy. Labeled cells (8.1%) were also observed in the contralateral T13-L3 DRG. In both FB and HRP groups, the major part of the labeled cells was located in L1 and L2. The sizes of HRP- and FB-labeled cells were smaller than those of unlabeled cells in the L1 and L2 DRG. The cumulative frequency distribution histogram for the diameter of HRP- and FB-labeled cells could be fitted by a normal distribution.

Amidines↗
PubMed1996

HLA DRB1 and DQB1 alleles and haplotypes influencing the progression of hepatitis C.

Some HLA class II alleles and haplotypes were examined by restriction fragment length polymorphism of corresponding DNA fragments amplified by the polymerase chain reaction in 117 patients with chronic hepatitis C in Japan. The prevalence rates were compared between patients and 1216 controls and in 67 patients with liver cirrhosis, of whom 20 had hepatocellular carcinoma and 50 patients with chronic hepatitis who did not have cirrhosis or hepatocellular carcinoma. Notably, DRB1*0405 (49% [95% confidence range 38-60%] vs. 26% [16-40%]; P < 0.05, relative risk [rr] = 2.8) and DQB1*0401 (43% [33-54%] vs. 22% [13-34%]; P < 0.05, rr = 2.1) were detected more frequently in patients with cirrhosis than in those without cirrhosis. By contrast, DRB1*0901 (11% [6-19%] vs. 28% [18-40%]; P < 0.05; rr = 0.3) and DQB1*0303 (11% [6-19%] vs. 36% [25-49%]; P < 0.01; rr = 0.2) were detected less frequently in patients with cirrhosis than those without cirrhosis. Accordingly, the DRB1*0405-DQB1*0401 haplotype was more common (43% [33-54%] vs. 22% [13-34%]; P < 0.05; rr = 2.7), while the DRB1*0901-DQB1*0303 haplotype was less common (9% [4-17%] vs. 28% [18-40%]; P < 0.05; rr = 0.3) in patients with cirrhosis than in those without cirrhosis. These results suggest that there would be HLA class II alleles and haplotypes which may be associated with an accelerated or slower progression of chronic hepatitis C towards cirrhosis and eventually to hepatocellular carcinoma.

Alleles↗