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Biomedical subjects

I Hasegawa

Publications and source records attributed to I Hasegawa.

At least 19 recordsLinked to original sources
PubMed2005

Comparison of artifacts on coronal reformation and axial CT pulmonary angiography images using single-detector and 4- and 8-detector multidetector-row helical CT scanners.

RATIONALE AND OBJECTIVES: The aim of this study is to compare the degree of stair-step artifact on coronal reformation computed tomographic (CT) pulmonary angiography images obtained using single-detector helical CT (SDCT), four-detector (4-MDCT), and eight-detector multidetector-row CT (8-MDCT) and compare the degree of motion artifact on the corresponding axial CT images. MATERIALS AND METHODS: Three groups of consecutive patients imaged by means of CT angiography for suspected pulmonary embolus were retrospectively identified by using CT records at our institution: (1) group A (n = 38), SDCT; (2) group B (n = 36), 4-MDCT; and (3) group C (n = 74), 8-MDCT. For each case, coronal multiplanar volume reformation maximal intensity projection images were created by using a standard technique. All images were reviewed in a randomized fashion by two thoracic radiologists who were blinded to the type of CT scanner. Stair-step artifact of pulmonary arteries on coronal reformation images was graded by consensus agreement using a four-point scale (0 = no artifact to 3 = severe artifact). Axial images were assessed for six parameters of motion artifact. The sum of these grades resulted in a total motion score, with a potential range of 0 (no motion) to 12 (severe motion). Statistical analysis was performed using the Mann-Whitney test. RESULTS: Stair-step artifacts were significantly higher for SDCT (mean, 2.9; median, 3) compared with 4-MDCT (mean, 2.2; median, 2; P < .0001) and 8-MDCT (mean, 1.5; median, 1; P < .0001). Total motion scores were significantly higher for SDCT (mean, 9.3) compared with 4-MDCT (mean, 8.4; P = .03) and 8-MDCT (mean, 6.8; P < .0001). CONCLUSION: Stair-step artifacts are significantly higher with SDCT compared with MDCT. For MDCT, eight-detector scanners produce images with significantly less artifact than four-detector scanners.

Adolescent↗
PubMed2005

Interactions between clarithromycin and digoxin in patients with end-stage renal disease.

OBJECTIVE: To report a significant increase in the serum levels of digoxin associated with the use of clarithromycin in six patients undergoing renal replacement therapy. CASE SUMMARY: All six patients were males with end-stage renal disease and in need of renal replacement therapy. Four patients were anuric. The mean age was 78.8 +/- 5.8 (66-83) years. All patients except one, who was treated by hemofiltration, were treated by hemodialysis. All patients except one, who had been treated with metildigoxin (0.35 mg/week), were also taking digoxin (0.375 mg/week). Clarithromycin was administered at a dose of 200-400 mg/day for the treatment of bronchitis in all patients. The concomitant administration of clarithromycin increased serum digoxin levels from 1.8-4.0-fold in all cases. In two of six cases, a high probability of digoxin intoxication and suspicion of digoxin intoxication was evident. In three of six cases, serum digoxin levels increased within 12 days after the co-administration of clarithromycin, while in the other three cases, serum digoxin levels were increased 53-190 days after the administration of clarithromycin. CONCLUSION: The simultaneous administration of clarithromycin caused an increase in digoxin levels in six patients undergoing renal replacement therapy. The increase in the serum digoxin can be attributed to the inhibition of P-glycoprotein in the intestine and/or bile capillary rather than the kidney by clarithromycin since renal function was dramatically impaired, and four of the patients were anuric. The issue of why serum digoxin levels were increased so late in three patients undergoing renal replacement is unclear. However, this interaction seemed to be clinically significant even in ESRD patients, whose renal function was highly impaired. The simultaneous use of digoxin and clarithromycin should be avoided even in patients undergoing renal replacement therapy whose renal function is impaired, since digoxin levels may increase unexpectedly.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Frequency and severity of air trapping at dynamic expiratory CT in patients with tracheobronchomalacia.

OBJECTIVE: The purpose of this study was to compare the frequency and severity of air trapping in patients with and without tracheobronchomalacia using dynamic expiratory volumetric CT. MATERIALS AND METHODS: The study group consisted of 20 subjects, including 10 patients with bronchoscopically proven tracheobronchomalacia and 10 control subjects of similar ages without tracheobronchomalacia. All 20 subjects underwent MDCT performed at the end of deep inspiration and during dynamic expiration. The images were analyzed at three lung levels, and the extent of air trapping was assessed visually using a 5-point scale. For each subject, a total air-trapping score was derived by summing the values for the three lung levels (possible range, 0-12). Statistical analysis was performed using the Mann-Whitney U test. RESULTS: In the tracheobronchomalacia group, 10 (100%) of 10 patients showed air trapping, with a median score of 5 (range, 2-12). In the control group, six (60%) of 10 subjects showed air trapping, with a median score of 2 (range, 0-3). The median total air-trapping score was significantly higher (p < 0.001) for the tracheobronchomalacia group compared with the control group. Excessive central airway collapse (expiratory reduction in cross-sectional area of > 50%) was seen on CT scans in all tracheobronchomalacia patients but in none of the control subjects. CONCLUSION: Air trapping was observed with a higher frequency and greater severity in patients with tracheobronchomalacia than in a control group of patients of similar ages without tracheobronchomalacia.

Adult↗
PubMed2001

Plasma triglyceride-rich lipoprotein remnants as a risk factor of 'Pokkuri disease'.

In our recent report, it remained unclear whether or not triglyceride-rich lipoprotein remnants (RLP) were associated with the risk of sudden coronary death in younger cases without coronary atherosclerosis that were detected in about 10% of all sudden coronary death cases in Japan. These cases were categorized as 'origin unknown, but suspected to be due to coronary spasm', the so called 'pokkuri disease' in Japan. The present study population consisted of 108 sudden death cases without coronary atherosclerosis [(pokkuri disease n=57) and non-cardiac sudden death (control n=51)] aged 20-69 years from Kanagawa prefecture in Japan. All individuals had died suddenly and unexpectedly, most had no significant history of medical conditions including cardiac symptoms and had not taken medications prior to death according to their medical records. All the autopsies were performed within 12 h after death. Plasma total cholesterol (TC), triglycerides (TG), phospholipids, RLP-C and RLP-TG, VLDL-C, LDL-C, HDL-C, apolipoproteins A-I, A-II, B, C-II, C-III, E, Lp (a) and homocysteine were measured in postmortem plasma samples. The TG-rich lipoprotein remnants measured as RLP-C and RLP-TG were significantly higher in pokkuri disease compared with controls both in fasting and postprandial states (P<0.05 and P<0.001), indicating that RLP-C and RLP-TG were the most significant risk factor in pokkuri disease among the parameters tested in this study. In conclusion the TG level in RLP (RLP-TG) appeared to be strongly associated with the risk of sudden death in the absence of coronary atherosclerosis (pokkuri disease).

Journal Article↗
PubMed2000

Neural mechanisms of memory retrieval: role of the prefrontal cortex.

In the primate brain, long-term memory is stored in the neocortical association area which is also engaged in sensory perception. The coded representation of memory is retrieved via interactions of hierarchically different cortical areas along bottom-up and top-down anatomical connections. The functional significance of the fronto-cortical top-down neuronal projections has been relevantly assessed in a new experimental paradigm using posterior-split-brain monkeys. When the splenium of the corpus callosum and the anterior commissure were selectively split, the bottom-up visual signal originating from the unilateral striate cortex could not reach the contralateral visual cortical areas. In this preparation, long-term memory acquired through visual stimulus-stimulus association learning was prevented from transferring across hemispheres. Nonetheless, following the presentation of a visual cue to one hemisphere, the prefrontal cortex could instruct the contralateral hemisphere to retrieve the correct stimulus specified by the cue. These results support the hypothesis that the prefrontal cortex can regulate memory recall in the absence of bottom-up sensory input. In humans, functional neuroimaging studies have revealed activation of a distributed neural network, including the prefrontal cortex, during memory retrieval tasks. Thus, the prefrontal cortex is consistently involved in retrieval of long-term memory in primates.

Animals↗
PubMed1999

Top-down signal from prefrontal cortex in executive control of memory retrieval.

Knowledge or experience is voluntarily recalled from memory by reactivation of the neural representations in the cerebral association cortex. In inferior temporal cortex, which serves as the storehouse of visual long-term memory, activation of mnemonic engrams through electric stimulation results in imagery recall in humans, and neurons can be dynamically activated by the necessity for memory recall in monkeys. Neuropsychological studies and previous split-brain experiments predicted that prefrontal cortex exerts executive control upon inferior temporal cortex in memory retrieval; however, no neuronal correlate of this process has ever been detected. Here we show evidence of the top-down signal from prefrontal cortex. In the absence of bottom-up visual inputs, single inferior temporal neurons were activated by the top-down signal, which conveyed information on semantic categorization imposed by visual stimulus-stimulus association. Behavioural performance was severely impaired with loss of the top-down signal. Control experiments confirmed that the signal was transmitted not through a subcortical but through a fronto-temporal cortical pathway. Thus, feedback projections from prefrontal cortex to the posterior association cortex appear to serve the executive control of voluntary recall.

Animals↗
PubMed1999

Effect of troglitazone on endocrine and ovulatory performance in women with insulin resistance-related polycystic ovary syndrome.

OBJECTIVE: To investigate the effect of troglitazone, a new antidiabetic agent that improves insulin resistance, on endocrine, metabolic, and ovulatory performance in women with insulin resistance-related polycystic ovary syndrome (PCOS). DESIGN: Prospective clinical study. SETTING: Infertility outpatient clinic, Niigata University Hospital, Niigata, Japan. PATIENT(S): Thirteen women with PCOS and insulin resistance. INTERVENTION(S): Troglitazone (400 mg/d) was administered for 12 weeks. MAIN OUTCOME MEASURE(S): Insulin and other hormone (gonadotropins, androgens) levels; various parameters relating to glucose and lipid metabolism before, during, and after troglitazone administration; and ovulation rate. RESULT(S): The mean (+/-SD) fasting insulin concentration was significantly reduced, from 18.3+/-8.9 to 10.5+/-7.1 microU/mL. The LH level was reduced from 9.7+/-3.4 to 4.8+/-3.9 mIU/mL and the testosterone level was reduced from 0.9+/-0.5 to 0.5+/-0.3 ng/mL in accordance. Atherosclerotic lipid levels also were normalized. Before troglitazone administration, the ovulation rate during clomiphene citrate therapy was 34.9% per cycle (15/43). This increased significantly to 72.7% (8/11) during troglitazone coadministration. Further, an ovulation rate of 42.3% (11/26) was achieved with troglitazone alone. CONCLUSION(S): In women with PCOS and insulin resistance, the reduction of hyperinsulinemia that is produced by troglitazone improves the hyperandrogenism that characterizes PCOS, restoring ovulation.

Adult↗
PubMed1999

Short communication: mapping of somatosensory cortices with functional magnetic resonance imaging in anaesthetized macaque monkeys.

Functional magnetic resonance imaging (fMRI) in macaque monkeys is emerging as a potent candidate to bridge the gap between data from human fMRI studies and data from anatomy, electrophysiology and lesion studies in monkeys. The primary (SI) and secondary (SII) somatosensory cortices are the principal regions for somatosensory information processing and contain systematic representations of the body surface map (somatotopy). To examine the functional organization of the somatosensory cortices in anaesthetized macaque monkeys with fMRI, we asked whether focal and differential activation could be observed in SI and SII in response to tactile stimulation with two parameters: body sides (right and left) and body regions (hand and face). We found that changes in stimulus parameters elicited differential focal activation in both SI and SII in two ways. First, the hand and face stimulation activated SI and SII in the contralateral, but not in the ipsilateral, hemisphere. Second, the hand and face stimulation differentially activated two adjacent regions in both SI and SII. These fMRI results appear to correlate with previous mapping studies by other methods in the macaque somatosensory cortices. This study shows the feasibility of fMRI studies in mapping multiple sensory areas in monkeys by which we can distinguish between adjacent functionally distinct regions.

Anesthesia↗
PubMed1999

Bronchopulmonary arterial anastomosis at the precapillary level in human lung. Visualization using CT angiography compared with microangiography of autopsied lung.

PURPOSE: To investigate the interrelationships between the bronchial and pulmonary circulations including the existence of precapillary bronchopulmonary arterial anastomoses. MATERIAL AND METHODS: CT of bronchial arteriography (BAG-CT) was performed in 10 patients and BAG-CT during a pulmonary artery block test (PA-block) in 5 patients with lung cancer. Bronchial and pulmonary circulations were evaluated in 5 autopsied normal lungs by injecting silicone rubber with different colors into the bronchial and pulmonary arteries. RESULTS: BAG-CT correlated well with the findings at silicone rubber injection into lung autopsy samples. BAG-CT demonstrated inflow of contrast medium into the pulmonary artery during PA-block in all cases, while no inflow was observed before and following reversal of PA-block. Mixed silicone rubber was observed in the lobar to subsubsegmental bronchial arteries in all cases and in the subsubsegmental pulmonary artery in one case. CONCLUSION: Precapillary bronchopulmonary arterial anastomoses may exist at the level of the lobar bronchi to the periphery. If either the pulmonary or bronchial circulation is disturbed, flow occurs inside the anastomoses to supplement the other flow, especially flow from the bronchial to the pulmonary arteries via the anastomoses, which occurs within 30 min.

Adolescent↗
PubMed1999

Memory retrieval under the control of the prefrontal cortex.

Memory retrieval is a process wherein a distributed neural network reactivates the brain's representation of past experiences. Sensory long-term memory is represented among a population of neurones in the modality-specific posterior association cortex. The coded representation of memory can be retrieved by interactions of hierarchically different cortical areas along bottom-up and top-down anatomical connections. We examined the function of the prefrontal cortex in memory retrieval by two different approaches. Firstly, a meta-analysis of brain imaging studies revealed that the prefrontal cortex is reliably activated by memory retrieval in humans. Secondly, in order to determine the causal relationship between the prefrontal activations and memory retrieval, we designed a new experimental paradigm using posterior-split-brain monkeys. Following section of the splenium of the corpus callosum and the anterior commissure, visual stimulus-stimulus association learning within one hemisphere did not transfer to the other. Nevertheless, when a visual cue was presented to one hemisphere, the prefrontal cortex could instruct the contralateral hemisphere to retrieve the correct stimulus specified by the cue. These findings suggest that the prefrontal cortex can regulate the recall of long-term memory in the absence of bottom-up sensory inputs.

Animals↗
PubMed1999

Polycystic ovary syndrome. Insulin resistance and ovulatory responses to clomiphene citrate.

OBJECTIVE: To evaluate insulin secretion detected on oral glucose tolerance testing in relation to clomiphene citrate (CC) responses in women with polycystic ovary syndrome (PCOS). STUDY DESIGN: A total of 37 PCOS women were enrolled. Plasma baseline levels of gonadotropins, sex hormone binding globulin, androstenedione, dehydroepiandrosterone sulfate and testosterone (T) were determined. Insulin and glucose serum concentrations were analyzed in all samples after a 75-g oral glucose tolerance test. A dose of 100 mg/d of CC was given for ovulation induction. Ovulation was detected by ultrasonographic observation in conjunction with a serum progesterone level. RESULTS: During three consecutive cycles of CC administration, two or more anovulatory cycles were observed in 12 of 37 PCOS women (defined as CC nonresponders). The serum T level and the area under the curve (AUC) of insulin were significantly higher in CC nonresponders. The receiver operating characteristic curve of the AUC of insulin provided the most appropriate cutoff point for the prediction of CC resistance. CONCLUSION: We found higher androgen secretion and insulin resistance in CC nonresponders. The AUC of insulin was the most reliable method for the prediction of CC resistance associated with insulin resistance.

Adult↗
PubMed1998

Callosal window between prefrontal cortices: cognitive interaction to retrieve long-term memory.

A perceptual image can be recalled from memory without sensory stimulation. However, the neural origin of memory retrieval remains unsettled. To examine whether memory retrieval can be regulated by top-down processes originating from the prefrontal cortex, a visual associative memory task was introduced into the partial split-brain paradigm in monkeys. Long-term memory acquired through stimulus-stimulus association did not transfer via the anterior corpus callosum, a key part interconnecting prefrontal cortices. Nonetheless, when a visual cue was presented to one hemisphere, the anterior callosum could instruct the other hemisphere to retrieve the correct stimulus specified by the cue. Thus, although visual long-term memory is stored in the temporal cortex, memory retrieval is under the executive control of the prefrontal cortex.

Analysis of Variance↗
PubMed1998

Prednisolone plus low-dose aspirin improves the implantation rate in women with autoimmune conditions who are undergoing in vitro fertilization.

OBJECTIVE: To evaluate the effect of prednisolone plus low-dose aspirin (PSL/LDA) in women with autoimmune conditions who were enrolled in an IVF-ET program. DESIGN: A retrospective clinical study. SETTING: In vitro fertilization unit, Niigata University Hospital, Niigata, Japan. PATIENT(S): Three hundred seven women who underwent IVF-ET between January 1996 and December 1997. INTERVENTION(S): Prednisolone (10 mg/d) and aspirin (81 mg/d) were administered to the women with autoantibodies who chose to participate. MAIN OUTCOME MEASURE(S): Pregnancy and implantation rates with IVF-ET. RESULT(S): Women undergoing IVF who had positive antinuclear antibodies, with or without antiphospholipid antibodies, had significantly lower pregnancy and implantation rates than did women without autoantibodies (14.8% versus 21.7% and 6.8% versus 10.4%, respectively). The administration of PSL/LDA to women with antinuclear antibodies significantly improved the outcome of IVF-ET (40.6% pregnancy rate and 20.3% implantation rate). CONCLUSION(S): A high proportion of women who are undergoing IVF-ET have autoantibodies, which are associated with poor IVF outcomes. The administration of PSL/LDA to these women may improve their implantation rate.

Adult↗
PubMed1998

Fatal bilateral adrenal hemorrhage following acute toluene poisoning: a case report.

CASE REPORT: A 19-year-old woman was admitted to the emergency center with the development of quadriparesis after prolonged inhalation of lacquer thinner (67% toluene). Laboratory findings were compatible with a distal renal tubular acidosis manifest as metabolic acidosis, hypokalemia, and hyperchloremia. Despite potassium replacement, her condition deteriorated drastically 30 hours later. Blood pressure became refractory to vasopressors, temperature was persistently above 40 degrees C, and death occurred 56 hours later. At autopsy, adrenal insufficiency secondary to bilateral adrenal hemorrhage was diagnosed. Bilateral adrenal hemorrhage should be considered as a potential cause of sudden clinical deterioration during treatment of serious toluene intoxication.

Acidosis, Renal Tubular↗
PubMed1998

[Combination of transcatheter arterial infusion of SMANCS and embolization (SMANCS-TAE) for hepatocellular carcinoma--second report].

Patients with unresectable hepatocellular carcinoma (hepatoma) with hypervascularity were treated by SMANCS-TAE. A superselective catheterization technique was used to inject gelatin sponge particles after administration of SMANCS. In 30 patients of first hepatoma treated by SMANCS-TAE. Grade 4 was obtained after 1.7(1-3) courses. The 2-year survival rate was 22%. Some of the 24 patients of second hepatoma treated by SMANCS-TAE have survived over 2 years. Sixteen patients with advanced hepatoma (Vp2-3 or T4) were treated only by SMANCS injection, but none survived over 1 year. SMANCS-TAE appears to have the same potential and safety as L-TAE, when used selectively. Moreover, we can reduce the course of treatment and obtain good QOL for hepatoma patients except in advanced cases.

Aged↗
PubMed1997

Chromosome analysis of aborted conceptuses of recurrent aborters positive for anticardiolipin antibody.

OBJECTIVE: To elucidate the relationship between anticardiolipin antibody and recurrent abortion. DESIGN: Prospective clinical study. SETTING: Institutional practice in which patients with recurrent abortion were registered at the outpatient clinic for infertility of Niigata University Hospital. PATIENT(S): Five hundred sixty-one patients with recurrent abortions and 148 patients who were not recurrent aborters and who had experienced sporadic abortion. INTERVENTION(S): Aborted conceptuses for chromosome analyses were collected from the patients. MAIN OUTCOME MEASURE(S): The positive rate of anticardiolipin antibody was assessed in patients with recurrent abortion. Chromosome analyses of aborted conceptuses were performed in 10 patients with positive anticardiolipin antibody who had experienced another pregnancy that resulted in repeated abortion. Similar analyses of aborted conceptuses from 148 sporadic early abortions (controls) were performed. RESULT(S): The incidence of chromosome abnormalities in anticardiolipin antibody-positive recurrent aborters was 20.0% (2 of 10 cases), which was significantly lower than that of patients with sporadic abortion (60.1%, 89 of 148 cases). CONCLUSION(S): The low incidence of chromosome abnormalities in aborted conceptuses of patients with positive anticardiolipin antibody suggests that this antibody is strongly implicated in the genesis of recurrent abortions.

Abortion, Habitual↗