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Biomedical subjects

S Koike

Publications and source records attributed to S Koike.

At least 73 records · Page 4Linked to original sources
PubMed1997

[Low-level lead exposure and children's intelligence from recent epidemiological studies in the U.S.A. and other countries to progress in reducing lead exposure and screening in the U.S.A].

From the 1980s many well-designed epidemiological studies have confirmed that low-level, subclinical lead exposure in early life is associated with decrements in children's intelligence. Neurodevelopmental deficits from exposure to a low level of lead have been held to be not only an American problem, but also a worldwide issue in the past decade. Good epidemiological studies were reported from England, Scotland, Germany, Greece, Australia and New Zealand. Well-designed cross-sectional and prospective studies were carried out to quantify the magnitude of the relation between full scale IQ in children aged five years or more and the burden of lead (PbB or PbT) in early life of children. Of five cross-sectional studies of blood lead, two demonstrated a significant inverse association between lead and IQ even after adjustment for confounders. Two other studies, however, showed no firm evidence of inverse association after adjustment for confounders, and the remaining study demonstrated no significant inverse association of five cross-sectional studies of tooth lead, two indicated an inverse association between tooth lead and IQ, two others showed no significant inverse association after adjustment for confounders, and the remaining one manifested no association. Of four prospective studies, two revealed strong evidence of an inverse association between blood lead at the age of around two years and IQ. Another one, however, revealed an inverse association between mean postnatal blood level and IQ, while the remaining one demonstrated no significant inverse association between IQ and postnatal blood lead level after adjustment for confounders. In a comprehensive review of 26 epidemiological studies since 1979, including a meta-analysis, Pococok et al. indicated that doubling of the body lead burden (from 10 to 20 micrograms/dl) blood lead or (from 5 to 10 micrograms/g) tooth lead is typically associated with a mean deficit in full-scale IQ of around 1-2 IQ points. Lead in interior household dust, exterior surface soil, and old residential lead paint, which is deteriorated or removed, constitute the major sources of lead poisoning in children in the United States. Infants and children, who typically engage in hand to mouth activities, frequently come into contact with lead dust in soil and on the floor. Marked declines both in air lead and blood lead concentrations are evident parallel to the phase-down of lead in gasoline and soldered cans by U.S. food processors. The major source of lead in drinking water is from lead pipes used in household plumbing. The CDC revised its guidelines concerning childhood lead poisoning, stating that community prevention activities should be triggered when a large percentage of children in a community have blood lead levels of 10 micrograms/dl, the lowest level at which neurodevelopmental effects were believed to occur. For children with blood lead level concentrations between 10 and 14 micrograms/dl, more frequent rescreening may be needed. For concentrations between 15 and 19 micrograms/dl, in addition to more frequent screening, nutritional and educational advice should be given. In cases where these levels persist, there should be environmental investigation and intervention. All children with blood levels of 20 micrograms/dl or greater should receive environmental evaluation and medical examination. Such children may need pharmacological treatment.

Australia↗
PubMed1997

[The causes and management of ischemic mitral regurgitation].

Ischemic mitral regurgitation (IMR) is recognized as one of the complications of coronary artery disease. The aim of this study is to evaluate the causes and surgical management of IMR. From October 1986 to March 1995, 443 of patients underwent isolated coronary artery bypass grafting (CABG). In forty-four of the patients (9.9%) who underwent isolated CABG, the severity of postoperative IMR was reduced by two or more grades by the Sellers index. Hemodynamic parameters of these patients included: left ventricle ejection fraction, left ventricle end-diastolic volume index and left ventricle regional wall motion. They were assessed by left ventriculography (LVG). In addition, cardiac index and pulmonary artery wedge pressure were assessed by S-G catheterization and mitral annulus diameter by ultrasonic echocardiography. Twenty-nine patients experienced an increase in IMR severity after CABG, one of whom required mitral valve replacement for cardiac failure, and later died due to low output syndrome postoperative. On the other hand, fifteen patients experience a reduction in IMR severity after CABG. We conclude that the causes of IMR were regional asynergy at the site of papillary muscle, mitral annulus dilation and left ventricle dilation. Our findings suggest that severe IMR patients required concomitant mitral valve surgery with CABG. Patients with mild or moderate IMR patients with mitral annulus dilation or regional asynergy at the site of mitral papillary muscle may require the same surgery.

Coronary Artery Bypass↗
PubMed1996

Relationship of neuropeptides to nitrergic innervation of the canine laryngeal glands.

The participation of vasoactive intestinal polypeptide (VIP) or calcitonin gene-related peptide (CGRP) in the nitrergic innervation of the canine laryngeal glands was investigated using a double-staining technique of NADPH-diaphorase (NADPHd) histochemistry and VIP or CGRP immunohistochemistry. NADPHd-positive nerve fibers with varicosities appeared to terminate in some acinar cells. Double staining revealed that NADPHd reactivity and VIP- or CGRP-like immunoreactivity were colocalized in some nerve fibers distributed around the acini. A cluster of NADPHd-positive cells were occasionally found in the larynx. Many NADPHd-positive cells had VIP-like immunoreactivity and no NADPHd-positive cells were CGRP-like immunoreactive. These findings suggest that nitric oxide participates in the neural control of the laryngeal exocrine secretion in cooperation with intrinsic VIP and/or extrinsic CGRP.

Animals↗
PubMed1996

Nitrergic neurons in the canine intrinsic laryngeal muscle.

Nitrergic ganglionic cells located in the canine intrinsic laryngeal muscle were studied by NADPH-diaphorase (NADPH-d) histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry. Cells intensely stained by NADPH-d histochemistry were found between the striated muscle fibers of the intrinsic laryngeal muscle. Most of these cells were bipolar or pseudounipolar in form. Some NADPH-d negative cells were observed to be enveloped in a mesh by varicose NADPH-d positive nerve fibers. The findings obtained by nNOS immunohistochemistry corresponded well with those obtained by NADPH-d histochemistry, indicating that NADPH-d activity in the ganglion in the intrinsic laryngeal muscle is nNOS. The present findings clearly indicate that some of the ganglion cells located in the canine intrinsic laryngeal muscle are nitrergic, and that the ganglionic cells synapse together with the participation of nitric oxide in integrating ganglionic cells.

Animals↗
PubMed1996

Superimposition of In-111 platelet SPECT and CT/MR imaging in intracardiac thrombus.

An initial attempt to superimpose in-111-labeled platelet SPECT over CT/MRI in two patients with intracardiac thrombus is presented. One patient was a 65-year-old woman with a history of mitral and tricuspid valve replacement. This patient had a large thrombus measuring 74 x 43 x 34 mm in the right atrium. Fusion imaging with CT showed increased in-111 activity on the surface of the thrombus, which was visualized as circular activity on a planar image. The other patient was a 72-year-old woman who had a thrombus measuring 17 x 14 x 12 mm at the cardiac apex. Planar imaging showed two discrete areas of abnormal in-111 activity. Superimposition of the SPECT image over MR revealed that one of these areas corresponded to the small thrombus, whereas the other related to a previous subendomyocardial biopsy. In both patients, the activity ratio of the abnormal in-111 accumulation versus the cardiac chamber on SPECT was greater than that on planar images. The correlation of in-111 platelet SPECT and CT/MRI was useful in accurately localizing the intracardiac thrombus.

Aged↗
PubMed1996

Nitrergic innervation of the rat larynx measured by nitric oxide synthase immunohistochemistry and NADPH-diaphorase histochemistry.

We evaluated the involvement of nitric oxide (NO) in the laryngeal innervation of rats using NADPH-diaphorase (NADPH-d) histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry. The findings obtained by NADPH-d histochemistry were identical with those obtained by nNOS immunohistochemistry, indicating that NADPH-d is nNOS in the laryngeal innervation system. We found NADPH-d-positive nerve fibers in every region of the larynx. In the epithelia of the mucosa, a small number of NADPH-d-positive nerve fibers were detected. The plexus of NADPH-d-positive nerve fibers was commonly found in the lamina propria, and some of these fibers were clearly associated with blood vessels. We also noted NADPH-d-positive nerve fibers in the region of laryngeal glands. Some of these fibers appeared to terminate in the glandular cells. We found NADPH-d-positive nerve fibers with varicosities in the intrinsic laryngeal muscle and free-ending nerve fibers on the muscle fiber. Motor end plate-like structures were positive for NADPH-d histochemistry. The NADPH-d-positive nerve fibers appeared to terminate at motor end plate-like structures in two of nine rats examined. A cluster of NADPH-d-positive neurons were occasionally present in the lamina propria of the laryngeal mucosa, in the connective tissue between the thyroid cartilage and intrinsic laryngeal muscle, and in the connective tissue near the cricoarytenoid joint. The present findings suggest that NO participates in the autonomic, sensory, and motor innervation of the larynx.

Animals↗
PubMed1996

Effects of inhibin on rat gonadal differentiation and development in vitro.

Previously we examined that inhibin-alpha subunit, transforming growth factor-beta 1 (TGF-beta 1) and epidermal growth factor (EGF) were expressed in sex-, cell- and stage-specific manners in perinatal rat gonads. To clarify effects of these growth factors on the rat gonadal differentiation and development, indifferent gonadal primordia with mesonephric tubules on gestational day 13 were cultured in vitro for 4 days in serum-free CMRL-1066 medium with inhibin, TGF-beta 1, EGF, anti-sera against these growth factors, testosterone or estradiol-17 beta, and then morphologically examined with reference to seminiferous tubule formation, germ cell division, Wolffian and Müllerian duct development. In male gonads, anti-inhibin-alpha serum suppressed the seminiferous tubule formation but inhibin, TGF-beta 1, EGF or steroid hormones did not affect on the tubule formation, germ cell proliferation nor gonoduct development. Seminiferous tubules in male gonads cultured in the medium containing anti-inhibin-alpha serum were incomplete and irregular in shape. On the other hand, in female gonads, inhibin suppressed the germ cell division and anti-inhibin-alpha serum led to the necrosis of germ cells, but other factors affected to neither sex cord formation nor germ cell division. Testosterone and estradiol-17 beta stimulated female Wolffian and Müllerian duct development, respectively. These results indicate that inhibin induces the seminiferous tubule formation and suppresses the female germ cell division in developing rat gonads in vitro.

Animals↗
PubMed1996

[Hypothalamic-adenohypophysial function of corticotropin releasing hormone (CRH)-ACTH system in hypoxic coma].

To evaluate the hypothalamic-adenohypophysial function of corticotropin releasing hormone (CRH)-ACTH system in severe hypoxic coma, basal serum values of ACTH and cortisol was measured, and insulin-tolerance test (ITT) and CRH stimulation test was performed in 15 cases. They were divided into two groups according to their prognosis: brain death (group A, 7 cases) and persistent vegetative state (group B, 8 cases). Basal values were within normal range in most cases apart from those measured in few days after the brain death, however, stimulation tests were negative in many cases. In group A, basal values in impending stage were significantly higher han those after the brain death (p < 0.05), however, both stimulation tests were negative regardless of the stage. In group B, basal values in acute stage, which was measured within a week after the hypoxia, were slightly higher (without significance) than those in chronic stage, which was measured more than a months after the hypoxia. CRH test and ITT were positive in 0/4 and 2/5 in acute stage, and in 4/8 and 3/8 in chronic stage, respectively. In early stage of group A, the impending stage, showed slightly higher basal values than those in acute stage of group B (without significance). ITT was negative in the former whereas positive in some cases (2/5) of the latter, however, CRH test was negative in both groups. These results suggest that endocrinological evaluation of the hypothalamic-adenohypophysial function may help to predict outcome in early stage of hypoxic coma.

Adolescent↗
PubMed1996

[Attempt of helical CT densitometry for assessing regional pulmonary ventilation].

Pulmonary dynamic CT densitometry during steady-state breathing was recorded and analyzed using helical CT scan in 14 patients with obstructive disorders involving small and large airways, and 2 with restrictive lung disease. The data set of 7-second, continuous helical scan at constant table position were reconstructed as 35 one-second temporarily overlapping images at 0.2- second intervals over 2-3 respiratory cycles, and regional CT densitometry was displayed. Normal lungs (5 volunteers) showed a regular sinusoidal curve, and maximal lung density change (LDC) was greater independent lungs than in independent lungs, with an average difference of 29.5 HU, indicating the gravitational effect In contrast, a regular sinusoidal curve was not shown in obstructive disorders, and a significant reduction in maximal LDC (33.7 +/- 22.6 HU) compared with the normal lungs (60.8 +/- 25.9 HU) (P < 0.001) was indicated. In contrast, no marked reduction in maximal LDC (53.7 +/- 28.6 HU) was shown in restrictive disorders. This method is fast and easy, and appears useful for the detection of ventilation abnormalities in obstructive lung disorders.

Absorptiometry, Photon↗
PubMed1996

Functional modification of vascular endothelial cells by cytokines during septic shock.

The function of vascular endothelial cells is to adjust blood vessel tonus, which contributes to maintaining homeostasis within blood vessels. However, inflammatory cytokines are produced in response to invasion by stimulating vascular endothelial cells and sometimes lead to shock or multiple organ failure. In the present study, we assessed cytokines in sepsis and septic shock, and various factors that are said to have a damaging effect on vascular endothelium. Endotoxin was measured by endotoxin-specific methods. Tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), and interleukin 8 (IL-8) were measured by enzyme-linked immunosorbent assay (ELISA). Endothelin-I was measured by radioimmunoassay (RIA). Nitric oxide was measured as metabolites of nitrite and nitrate oxides (NOx) by a method based on the Griess method. Thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (PGF 1 alpha) were both measured by RIA. All of the factors except endotoxin were significantly higher in the septic shock group than in the non-shock group and significantly higher in the non-survivor group than in the survivor group. Significant correlations were also found between endothelin-1 and NOx and between TXB2 and PG1 alpha. Significant correlations were also found between TNF-alpha and IL-6, endothelin-1, NOx and TXB2, but no significant correlations were detected between any of them and endotoxin. In serious diseases such as septic shock, the vascular endothelial constricting factors, endothelin and TXB2, and the blood vessel relaxing factors NOx and PGF1 alpha increase almost simultaneously. This suggests that the body's regulating mechanisms are disrupted in these serious conditions. The results of this study also suggest that inflammatory cytokines may be involved in stimulating the production of these factors.

Adult↗
PubMed1996

Dynamic pulmonary SPECT of xenon-133 gas washout.

UNLABELLED: A triple-detector SPECT data acquisition mode of "continuous repetitive rotation acquisition" was applied to dynamic pulmonary SPECT with 133Xe gas. METHODS: Subjects included 7 healthy volunteers, 22 patients with a space-occupying mass lesion, 22 with obstructive lung disease and 10 with restrictive lung disease. Following rebreathing of 133Xe, equilibrium and washout SPECT images during spontaneous breathing were acquired every 30 sec for 5-7 min. Regional 133Xe washout was assessed by the real half-time (T1/2) and mean transit time (MTT) images. RESULTS: SPECT and MTT images represented a gravity-induced gradient of ventilation in normal lungs and detailed the distribution of heterogeneous 133Xe washout in patient's lungs with or without abnormalities on chest x-ray CT. The T1/2 (111.4 +/- 26.4 sec) and its coefficient of variation (0.36 +/- 0.13) in obstructive lung diseases were significantly different from those (56.8 +/- 3.9 sec and 0.16 +/- 0.15) in restrictive lung diseases (p < 0.001, p < 0.05, respectively). Comparison of SPECT and planar studies assessed in 19 patients revealed superiority of SPECT in detecting ventilatory abnormalities and a high correlation of T1/2 between the two studies ( r= 0.977, p < 0.001). CONCLUSION: This modality has excellent potential for elucidating the distribution and nature of ventilatory abnormalities.

Administration, Inhalation↗
PubMed1996

[A case of coronary perforation after directional coronary atherectomy].

Directional coronary atherectomy was performed on a 69-year-old female with angina pectoris. She suffered from coronary perforation as a result of cardiac tamponade and shock. Pericardial drainage and hemostasis were performed immediately using a perfusion catheter. The patient was transferred to the operating room for perforation repair and coronary artery bypass grafting to the distal portion of the left anterior descending artery. The procedure was performed successfully. Although acute coronary perforation associated with directional coronary atherectomy is rare, it can be managed temporarily by a perfusion catheter and we successfully performed coronary artery bypass grafting.

Aged↗
PubMed1995

Identification of a DNA element determining synaptic expression of the mouse acetylcholine receptor delta-subunit gene.

mRNAs for acetylcholine receptor genes are highly concentrated in the endplate region of adult skeletal muscle largely as a result of a transcription restricted to the subneural nuclei. To identify the regulatory elements involved, we employed a DNA injection of a plasmid containing a fragment of the acetylcholine receptor delta-subunit gene promoter (positions -839 to +45) linked to the reporter gene lacZ with a nuclear localization signal. Injection of the wild-type construct into mouse leg muscles yielded preferential expression of the reporter gene in the synaptic region. Analysis of various mutant promoters resulted in the identification of a DNA element (positions -60 to -49), referred to as the N box, that plays a critical role in subneural expression. Disruption of this 12-bp element in the context of a mouse delta-subunit promoter from positions -839 to +45 gives widespread expression of the reporter gene throughout the entire muscle fiber, indicating that this element is a silencer that represses delta-subunit gene transcription in extrajunctional areas. On the other hand, this element inserted upstream of a heterologous basal promoter preferentially enhances expression in the endplate region. This element therefore regulates the restricted expression of the delta-subunit gene both as an enhancer at the endplate level and as a silencer in extrajunctional areas. Furthermore, gel-shift experiments with mouse muscle extracts reveal an activity that specifically binds the 6-bp sequence TTCCGG of this element, suggesting that a transcription factor(s) controls the expression of the delta-subunit gene via this element.

Animals↗