Biomedical subjects

R Tamura

Publications and source records attributed to R Tamura.

At least 37 records · Page 2Linked to original sources

PubMed2000

Sacrococcygeal teratoma with hydrops fetalis and bilateral hydronephrosis.

A 29-year-old Japanese primipara with fetal sacrococcygeal teratoma and hydronephrosis was referred to our department at 22 weeks of gestation. The preload index of the inferior vena cava (PLI) was 0.75 and fetal cardiac failure was suspected at 28 weeks of gestation. The sodium and chloride concentrations and osmolarity of the fetal urine were 96 mEq/L, 81 mEq/L and 204 mOsm/L, respectively, and we predicted a good renal function. Then, a vesico-amniotic shunting operation was performed at 28 weeks of gestation to keep the renal function and PLI decreased 0.41 after this operation. At 30 weeks of gestation, the fetus was delivered by a cesarean section owing to preterm PROM and a huge growing sacrococcygeal teratoma. The baby was female, weighing 2,020 g, and the 1 minute Apgar score was 1. She died almost 7 hours after birth due to respiratory insufficiency. An autopsy confirmed bilateral hydronephrosis, urethral stenosis, sacrococcygeal immature teratoma, and pulmonary hypoplasia. The size of this tumor revealed 80 x 70 x 45 mm in intrapelvic cavity and 130 x 90 x 50 mm out of body, and this tumor was classified as Type II according to the American Academy of Pediatrics Surgery Section classification.

Adult↗

PubMed2000

[A comparative study of the prognosis for Japanese patients with idiopathic interstitial pneumonia or BOOP based on histopathologic subsets].

We explored the prognosis for 123 patients with either idiopathic interstitial pneumonia (IIP) or bronchiolitis obliterans organizing pneumonia (BOOP). All patients underwent either open lung biopsy or thoracoscopic lung biopsy procedures. The histopathologic diagnosis of IIP included patients with usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), and desquamative interstitial pneumonia with respiratory bronchiolitis-associated interstitial lung disease. The prognosis was poorest for patients with a histologic diagnosis of UIP, and excellent for those who received a diagnosis of BOOP. Although the prognosis is generally considered to be good for patients with NSIP, some NSIP patients in our study died. Histopathologic diagnosis based on surgical lung biopsy is useful in evaluating the prognosis for patients with IIP.

Aged↗

PubMed2000

[New duct caliber measurement methods on magnetic resonance cholangiopancreatography].

PURPOSE: To report the feasibility of new duct caliber measurement methods using signal intensity on MR cholangiopancreatography (MRCP). MATERIALS AND METHODS: A phantom with 0.25-8 mm caliber ducts was imaged with a 1.5-Tesla MR system using the usual MRCP sequence. Each caliber was measured by conventional method (full width at half maximum, FWHM) and two new methods: the maximum intensity measurement method (MIM), in which caliber was calculated from maximum signal intensity, and the area intensity measurement method (AIM), in which caliber was calculated from the area under the signal intensity curve. Errors in calculated caliber were compared among the three methods of measurement. RESULTS: Mean measurement errors of each caliber for 1-8 mm ducts by MIM [14% (2.1-25%)] and by AIM [6.8% (0.4-16%)] were significantly lower than those by FWHM [30% (17-64%)]. AIM was significantly more accurate than MIM for caliber measurement of ducts over 1 mm. CONCLUSION: Two new caliber measurement methods for pancreatobiliary ducts in MRCP, MIM and AIM are accurate and should play an important role in clinical MRCP.

Bile Ducts↗

PubMed1999

Effects of T-588, a newly synthesized cognitive enhancer, on hippocampal CA1 neurons in rat brain tissue slices.

The effects of a newly synthesized cognitive enhancer, (-)-R-alpha-[[2-(diethylamino) ethoxy] methyl] benzo [b] thiophene-5-methanol hydrochloride (T-588), on the membrane properties of hippocampal CA1 neurons were investigated in a rat brain slice preparation. T-588 produced a slow and long-lasting depolarization of CA1 neurons with an increase in membrane resistance; this action showed close similarity to that of acetylcholine (ACh). However, the action of T-588 was not affected by atropine, tetrodotoxin or DL-2-amino-5-phosphonovalerate, while the action of ACh was blocked by atropine. The estimated reversal potential of this T-588 effect was near -90 mV which is the reversal potential of potassium ions in CA1 neurons. In the whole-cell voltage-clamp study, T-588 produced a reversible block of the outward potassium current in CA1 neurons. T-588 did not block the afterhyperpolarization evoked by an intracellular current injection, while ACh suppressed it. These results suggest that T-588 has a direct effect on CA1 neurons independent of its cholinergic activity, resulting from blockade of a conductance carried predominantly by potassium ions.

2-Amino-5-phosphonovalerate↗

PubMed1999

Spatial- and task-dependent neuronal responses during real and virtual translocation in the monkey hippocampal formation.

Neuropsychological data in humans demonstrated a pivotal role of the medial temporal lobe, including the hippocampal formation (HF) and the parahippocampal gyrus (PH), in allocentric (environment-centered) spatial learning and memory. In the present study, the functional significance of the monkey HF and PH neurons in allocentric spatial processing was analyzed during performance of the spatial tasks. In the tasks, the monkey either freely moved to one of four reward areas in the experimental field by driving a cab that the monkey rode (real translocation task) or freely moved a pointer to one of four reward areas on the monitor (virtual translocation task) by manipulating a joystick. Of 389 neurons recorded from the monkey HF and PH, 166 had place fields that displayed increased activity in a specific area in the experimental field and/or on the monitor (location-differential neurons). More HF and PH neurons responded in the real translocation task. These neurons had low mean spontaneous firing rates (0.96 spikes/sec), similar to those of rodent HF place cells. The remaining nonresponsive neurons had significantly higher mean firing rates (8. 39 spikes/sec), similar to interneurons or theta cells in the rodent HF. Furthermore, most location-differential neurons showed different responses in different tasks. These results suggest that the HF and PH are crucial in allocentric information processing and, moreover, that the HF can encode different reference frames that are context or task-dependent. This may be the neural basis of episodic memory.

Animals↗

PubMed1999

Comparison of medial and lateral septal neuron activity during performance of spatial tasks in rats.

The septal complex, having close and reciprocal connections with the hippocampus, is known to play an important role in learning and memory. Anatomically, the septal complex is divided into the medial and lateral areas (MS and LS). In the present study, in order to elucidate functional differences between the MS and LS, we recorded single unit activity in the MS or LS and electroencephalogram (EEG) in the hippocampus simultaneously while the rats performed the following 2 spatial tasks in an open-field chamber. In task 1, the rat received rewarding intracranial electrical stimulation (ICES) when it entered in a reward place that was set randomly in the open field in each trial. In task 2, the rat received rewarding ICES when it alternately visited two fixed reward places in the open field. Unit activity was analyzed in relation to the pattern of hippocampal EEG, and rat's location, locomotion direction and locomotion speed in the spatial tasks. A total of 47 neurons were recorded in the septal complex (MS, 19; LS, 28). The majority of neurons with activity correlated with hippocampal EEG were found in the MS (14/19). All of the neurons with place-related activity (an increase in unit activity when the rat was in a specific location in the open field) were found in the LS (n = 15). The majority of neurons with direction-related activity were found in the LS (18/23). Twenty-one neurons displayed speed-related activity (MS, 9; LS, 12). The present results indicate that (1) the MS is directly involved in the formation and control of hippocampal EEG patterns, and (2) the LS is important for the processing and integration of spatial information in the environment.

Animals↗

PubMed1999

The keratinocyte-derived cytokine IL-7 increases adhesion of the epidermal T cell subset to the skin basement membrane protein laminin-5.

Human epidermis contains a subset of epidermal T cells that can mount an immune response by migrating through the skin and into the peripheral lymphnodes to proliferate before re-entering the epidermis. The cytokine IL-7 is shown to be localized to the basement membrane of normal human skin. Furthermore, culturing in the presence of IL-7 causes increased adhesion of epidermal T cells but not peripheral blood T cells to the major epidermal basement membrane protein, laminin-5. The mechanism for increased T cell adhesion to laminin-5 is due, at least in part, to an increase in the cell surface expression of the integrin alpha3beta1. Epidermal T cells cultured in IL-7 that are strongly adherent to laminin-5 are shown by flow cytometry to consist of a variety of subsets; therefore, the increase in cell adhesion is not due to an outgrowth of one T cell subset during culturing. We hypothesize that in vivo, exposure to IL-7 is required for epidermal T cell adhesion to laminin-5.

Adult↗

PubMed1999

Convenient Assay for Settlement Inducing Substances of Barnacles.

A convenient assay method for estimation of barnacle, Balanus amphitrite, settlement inductive activity was developed. To avoid the inductive effect by comrades and laborious observation requirements, cyprid larvae were put individually into wells of a 96-well plate. The settlement ratio from the experiment without any inducers was quite low; therefore this assay allowed easy estimation of settlement inductive activities. Some known inductive agents, such as serotonin and barnacle extracts, clearly showed inductive activities. This assay method is proven to be suitable for estimation of barnacle settlement-inducing activities of both water-soluble and -insoluble compounds.

Journal Article↗

PubMed1999

Activation of monocytes in vivo causes intracellular accumulation of lipoprotein-derived lipids and marked hypocholesterolemia--a possible pathogenesis of necrobiotic xanthogranuloma.

Necrobiotic xanthogranuloma (NXG) is a rare histiocytic disease with generalized xanthomatosis. However, most cases with NXG are normolipidemic or hypolipidemic. The mechanism for the formation of xanthoma in NXG has not yet been clarified. We observed a case of NXG with severe hypocholesterolemia (total cholesterol: 1.69 mmol/l) and analyzed the function of monocytes in this case. Histological examinations by light microscopy revealed a large amount of lipid deposition in the patient's freshly isolated monocytes. The patient's monocytes showed a 3-fold increase in cholesteryl ester content and a 3-fold enhancement of acetyl low density lipoprotein (LDL) uptake compared with the control monocytes. However, no significant difference was noted in the expression of CD36 protein and the mRNA levels of scavenger receptor-class A (SR-A) between the monocytes of the patient and the control. The phagocytotic ability of the patient's monocytes was enhanced 1.5-fold compared with that of the control monocytes. These findings suggest that the activated monocytes may have degraded the modified LDL via a pathway other than CD36 or SR-A, and accumulated a great amount of lipids in vivo. In conclusion, the present study has demonstrated a possible pathogenesis of NXG that the activation of monocytes in vivo may contribute to the intracellular accumulation of lipoprotein-derived lipids leading to non-inherited xanthomatosis and the marked hypocholesterolemia.

Aged↗

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

Fluoxetine versus amitriptyline in the treatment of major depression with associated anxiety (anxious depression): a double-blind comparison.

Although common in clinical settings, major depressive disorder with associated anxious symptoms ('anxious depression') has not been well studied in antidepressant clinical trials. The aim of this study was to compare the effects of fluoxetine versus amitriptyline in this group of patients. After a single-blind placebo run-in period of 2 weeks, patients were treated on a double-blind basis with fluoxetine or amitriptyline for 8 weeks. Assessment instruments included: 21-item Hamilton Rating Scale for Depression, Hamilton Rating Scale for Anxiety, Clinical Global Impressions, Raskin Depression Scale and Covi Anxiety Scale. A total of 157 patients were randomized to either fluoxetine or amitriptyline. Fluoxetine was given at a fixed dose of 20 mg/day and amitriptyline was given in a range of 50-250 mg/day (mean of 138.1 mg/day). Fluoxetine was comparable to amitriptyline in all efficacy measures except the HAMD sleep factor. Unwanted effects were more frequent and more severe in the amitriptyline-treated patients. Fluoxetine was comparably efficacious to amitriptyline in the treatment of major depression with associated anxiety. Since fluoxetine was far better tolerated, it is a promising alternative for this frequent and disabling condition.

Adult↗

PubMed1999

CD36, a novel receptor for oxidized low-density lipoproteins, is highly expressed on lipid-laden macrophages in human atherosclerotic aorta.

CD36 has been reported to be a receptor for oxidized LDL (Ox-LDL). In our previous study, the uptake of Ox-LDL in CD36-deficient macrophages was reduced by approximately 50% compared with that in control macrophages, suggesting an important role of CD36 as a receptor for Ox-LDL in humans. In the current study, we examined the immunohistochemical localization of CD36 in human aorta in comparison with that of scavenger receptor class A type I and type II (SRA). Cryostat sections were made from aortic tissues. For immunohistochemical staining, the following antibodies were used: (1) FA6-152, anti-CD36 antibody, and (2) SRI-2, which recognizes both type I and type II SRAs. Immunohistochemical staining for CD36 and SRA was performed using labeled streptavidin method. In macrophages scattered in aortic walls without atherosclerotic lesions, the expression of CD36 was hardly observed, whereas that of SRA was detected weakly but consistently. In contrast, in atherosclerotic lesions, macrophages around the core region showed a weak immunoreactivity to CD36 and a strong immunoreactivity to SRA. Furthermore, lipid-laden macrophages, which mainly existed in the core region, had a strongly positive immunoreactivity to CD36, but a low or moderate level of immunoreactivity to SRA. The distributions of CD36 and SRA were different from each other, and especially foamed, large-sized macrophages in atherosclerotic plaques tended to more abundantly express CD36 protein. These data demonstrate, for the first time, that the expression of both CD36 and SRA might be differentially regulated in aortic walls, and might play different roles in the formation of foam cells in atherosclerotic lesions.

Adult↗

PubMed1999

Continuing treatment of panic disorder after acute response: randomised, placebo-controlled trial with fluoxetine. The Fluoxetine Panic Disorder Study Group.

BACKGROUND: Data concerning appropriate treatment in panic disorder following an initial response to acute therapy are limited. AIMS: To assess the safety and efficacy of continued fluoxetine treatment following successful acute therapy of panic disorder. METHOD: Patients who responded to acute fluoxetine treatment were randomised to 24 weeks of continued fluoxetine or placebo. RESULTS: Fluoxetine responders randomised to continue on their acute-phase fluoxetine dose experienced statistically significant improvement in panic attack frequency and phobia rating scale score over 24 weeks of therapy, while those switched to placebo experienced statistically significant worsening in Hamilton Anxiety (HAM-A), Hamilton Depression (HAM-D) and SCL-90-R rating scores. CONCLUSIONS: Fluoxetine was associated with improved clinical outcomes compared with placebo during continuation therapy.

Adult↗

PubMed1998

Examination of colocalization of calcitonin gene-related peptide- and substance P-like immunoreactivity in the knee joint of the dog.

It is generally assumed that the majority of substance P (SP)-containing afferents are also immunoreactive for calcitonin gene-related peptide (CGRP). In order to determine whether this is also the case in articular afferents where the contents of these peptides are low, we carried out a double labeling study using Fast Blue (FB) as a retrograde tracer injected into the center of the knee joint cavity of the dog together with immunohistochemistry for SP and CGRP. After 7-36 days of survival, dorsal root ganglia (DRGs, L4-S1) were removed. Labeled cells were found mainly (94%) in L5 - 6 DRGs, and SP- and CGRP-like immunoreactivity was found in about 17 and 29% of FB-labeled cells, respectively. The coexistence of SP and CGRP was observed in 10.4% of articular afferents and only 62.7% of SP-positive articular neurons contained CGRP, a much lower ratio than in other afferents of the dog such as testicular afferents. Our data suggest that these peptides are not always released together and that they do not always work together in the joint under normal conditions.

Animals↗

PubMed1998

Fibroblasts as target and effector cells in Japanese patients with sarcoidosis.

Fibroblasts play a crucial role in progressive lung fibrosis, acting not only as target cells but also as effector cells. To clarify these functions in sarcoidosis, lung fibroblasts from Japanese sarcoid patients were studied for their proliferative capacity and cytokine productivity. Fibroblasts were cultured from transbronchial lung biopsy specimens from seven patients with sarcoidosis. As a comparison, fibroblasts from open lung biopsy specimens of four patients with idiopathic pulmonary fibrosis (IPF) were studied. For controls, fibroblasts were cultured from specimens of normal resected lung tissue of five patients with localized lung cancer. The proliferative activity of cultured fibroblasts from patients with sarcoidosis was highest among the three groups (p < 0.05). However, the proliferative capacity in all groups was suppressed when fibroblasts were cultured with interleukin-1beta (IL-1beta). No significant differences were noted in the degree of inhibition among the three groups. Addition of interferon-gamma (IFN-gamma) also resulted in inhibition of fibroblast growth in all groups, but the degree of inhibition was significantly greater in both the sarcoid and IPF groups than in controls (p < 0.05). The amount of interleukin-6 (IL-6) in the culture supernatants from sarcoid fibroblasts cocultured with IL-1beta was significantly higher than in controls. Sarcoid fibroblasts are not only proliferatively active but also possess effector cell function to produce cytokines. IL-6 may enhance the immunologic reaction to sarcoidosis and cause the disease to become chronic. IFN-gamma suppresses proliferation of sarcoid fibroblasts and may prevent fibrotic changes of the lungs in the Japanese sarcoid patients.

Adult↗

PubMed1998

Troglitazone enhances glucose uptake and inhibits mitogen-activated protein kinase in human aortic smooth muscle cells.

The thiazolidinedione analogue troglitazone is an antidiabetic agent that improves insulin resistance in rodents and humans. Although coronary artery disease is common in patients with the insulin resistance syndrome, the effects of troglitazone on smooth muscle cells (SMC) have not been fully elucidated. We therefore examined the effects of troglitazone on cell growth and glucose uptake in human aortic SMC. Mitogen-activated protein (MAP) kinase activity and glucose transporter (Glut) 1 mRNA levels were also studied. In the absence of troglitazone, insulin (10(-7) M) caused a 2-fold increase of DNA synthesis in SMC and troglitazone suppressed the increase of DNA synthesis in a dose-dependent manner. This growth suppression was accompanied by inhibition of MAP kinase activity. On the other hand, troglitazone significantly increased Glut 1 mRNA and enhanced glucose uptake in SMC. These results suggest that troglitazone affects the insulin signaling pathways in SMC and suppresses growth while promoting glucose uptake. Our findings support the application of troglitazone as an inhibitor of SMC proliferation in patients with insulin resistance.

Aorta↗

PubMed1998

Generators of visual evoked potentials investigated by dipole tracing in the human occipital cortex.

Current source generators (dipoles) of the human visual evoked potentials to pattern-onset stimuli were investigated with the dipole tracing method, using a realistic four-layer head model of scalp-skull-fluid-brain, which can equate the surface potential distributions on a scalp to one or two corresponding equivalent dipoles. Three healthy adult human subjects were used, and 29 electrodes were set on a scalp of each subject. Visual stimulus of a checkerboard pattern was presented for 250 ms in each of eight different visual fields (central and peripheral parts of each of four quadrant fields). The visual evoked potentials consisting of initial positive-late negative waves (CI and CII components designated by Jeffreys and Axford) were recorded mainly on the occipital region contralateral to stimulated visual fields. The initial positive wave (CI) of visual evoked potentials were divided into two components: early component of the CI (e-CI--an early small positive deflection with approximate peak latency of 70-90 ms) and late component of the CI (l-CI--a late large positive deflection with approximate peak latency of 100-120 ms). The dipole with a fit exceeding 98% dipolarity with our model at the shortest latencies was defined as an "earliest dipole" of the evoked potentials, produced by the primary responses in the occipital cortex to an afferent volley from the lateral geniculate body. These earliest dipoles, for eight different visual field stimulations, were estimated at the approximate peak of the e-CI. Estimated dipoles were superimposed on a three-dimensional magnetic resonance image of each subject's brain. Earliest dipoles for right upper and right lower quadrant-field stimulations were located at the left calcarine cortices below and above the calcarine fissure, respectively; earliest dipoles for left upper and left lower quadrant-field stimulations were located at the right calcarine cortices below and above the calcarine fissure, respectively. Furthermore, earliest dipoles for central and peripheral quadrant-field stimulations were located posteriorly and anteriorly in the calcarine cortex, respectively. The results from these non-invasive analyses of visual evoked potentials indicated topographic localization of the dipoles around the calcarine fissure based on the loci of the visual fields. This was comparable to the retinotopy of the human occipital lobe based on clinicopathological studies.

Adult↗

PubMed1998

Peri-ovarian adhesions interfere with the diffusion of gonadotrophin into the follicular fluid.

In previous studies, patients with severe peri-ovarian adhesions have been found to show low pregnancy rates and a poor response to gonadotrophin stimulation during in-vitro fertilization (IVF) treatment. The purpose of this retrospective pharmacokinetic study was to assess the diffusion of exogenous human chorionic gonadotrophin (HCG) in patients with peri-ovarian adhesions by examining the concentration of exogenous HCG in the follicular fluid in patients undergoing down-regulation and IVF due to infertility. The patients underwent laparoscopic examination for the scoring of peri-ovarian adhesions (using the classification of adnexal adhesions adopted by the American Fertility Society, a score of 0 means no adhesions, and a score of 32 represents bilateral expanded dense adhesions). Oocytes were recovered after human menopausal gonadotrophin-human chorionic gonadotrophin (HMG-HCG) stimulation with gonadotrophin-releasing hormone agonist. Serum and follicular fluid were collected at the time of oocyte recovery for measuring the HCG ratio (the follicular HCG concentration to the serum HCG concentration; a reflection of the diffusion of exogenous gonadotrophin) by time-resolved fluoroimmunoassay. A negative correlation was found between the number of oocytes recovered and the peri-ovarian adhesion score (r = -0.62, P < 0.01). In a given patient, the follicular HCG concentration was always lower than the serum HCG at the time of oocyte recovery. The HCG ratio in all samples was 0.9 or less (0.51 +/- 0.20; range, 0.09-0.90). Significant negative correlations were found between the peri-ovarian adhesion score and both the follicular HCG concentration (r = -0.80, P < 0.01) and the HCG ratio (r = -0.75, P < 0.01). In conclusion, severe peri-ovarian adhesions interfered with the diffusion of exogenous gonadotrophin into the follicular fluid during IVF treatment. Thus, the diffusion of exogenous gonadotrophin into the follicular fluid may represent a new parameter in the assessment of ovarian blood flow and IVF outcome.

Adult↗