Biomedical subjects

Satoru Shimizu

Publications and source records attributed to Satoru Shimizu.

46 records · Page 3Linked to original sources

PubMed2003

Transacylation of alpha-aryl-beta-keto esters.

The acyl group of an alpha-aryl-beta-keto ester was readily transferred to N-, O-, and S-nucleophiles. The transacylation from arylated diethyl 3-oxoglutarate to amines led to unsymmetrical malonic acid amide esters in high yields. The present reaction proceeded under mild conditions without formation of detectable byproducts. Only simple experimental manipulations were required. This reaction was also found to be sensitive to steric factors, which enabled the chemoselective monoacylation of diamines and amino alcohols without any modifications such as protection.

Journal Article↗

PubMed2003

Bruch's membrane of the brachymorphic mouse.

Bruch's membrane exists between the retinal pigment epithelium and the choriocapillary endothelium. Its structure is very complicated, having five sublayers containing basement membranes of retinal pigment epithelium and choriocapillary endothelium, outer and inner collagenous layers, and a central elastic layer. In the development of Bruch's membrane in normal mice, both basement membranes are created first. Secondarily, collagen fibers are accumulated in the space between these basement membranes and then form a collagenous layer. Finally, the elastic layer elaborated in the collagenous layer separates this into outer and inner collagenous layers. Brachymorphic mice have a disorder in the sulfation pathway, resulting in undersulfation. Consequently, in Bruch's membrane of brachymorphic mice, the expression of decorin, a small proteoglycan containing chondroitin sulfate and an indispensable component in collagen assembly, is at a very low level. It is clear that hypoplasia of the collagenous layer in Bruch's membrane of brachymorphic mice induces a disorder in the following formation of the elastic layer. These findings suggest that the formation of the collagenous layer, regulated with acidic glycoconjugates such as decorin, is important in the development of Bruch's membrane.

Animals↗

PubMed2003

Structural characterization of triacylglycerol in several oils containing gamma-linolenic acid.

The differences are reported in the triacylglycerol (TG) structures of oils containing gamma-linolenic acid (GLA) from Oenothera biennis Linn seed oil (OBLO) from the wild plant, evening primrose seed oil (EPO) from a cultured plant, and bio-GLA oil (BIO) from a mold, the physiological functions of which were ascertained by animal testing. Reverse-phase high-performance liquid chromatographic separation detected 12 TG peaks each for OBLO and EPO, and 28 TG peaks for BIO. TG-containing GLA were composed of five molecular species each in OBLO and EPO, and ten molecular species in BIO. The totals of the molecular species containing GLA were 29.8% in OBLO, 23.8% in EPO, and 56.6% in BIO. In OBLO, the GLA level at the sn-2 position of the major TG species was higher than that in EPO. In BIO, the GLA level at the sn-2 position of the major TG species was lower than those in OBLO and EPO.

Chromatography, Gas↗

PubMed2003

Risk factors for adrenal crisis in patients with adrenal insufficiency.

Patients with adrenal insufficiency have a life-threatening risk of adrenal crisis, thus preventing adrenal crisis is an important clinical issue. In order to clarify the risk factors for adrenal crisis, the medical records of 137 patients with established adrenal insufficiency were retrospectively investigated. The explanatory variables analyzed were gender, etiology of hypoadrenalism, class of adrenocortical hormone replaced, duration of steroid replacement, age at time of survey, age at time of diagnosis of hypoadrenalism, state of other hormone deficiencies (growth hormone and sex steroids), diabetes insipidus, and mental disorder. Diagnosis of adrenal crisis was based on physical and laboratory findings. Forty (29%) of the 137 patients had at least one episode of adrenal crisis. Based on the Akaike Information Criterion (AIC), steroid replacement therapy of more than 4 yrs' duration was the largest single contributor to the occurrence of an adrenal crisis, followed by mental disorder and sex steroid deficiency. In the subclass of patients with secondary adrenal insufficiency (N = 115), sex steroid deficiency was the greatest risk factor. Patients with untreated hypogonadism had a significantly higher relative risk of 3.70 (95% confidential interval: 1.71-7.98) compared to those without hypogonadism or with treated hypogonadism. Furthermore, among patients with hypogonadism aged younger than 50 yrs, those treated with sex hormone (5/51: 10%) suffered less frequently from adrenal crisis than those untreated (7/11: 64%, p = 0.0004). In conclusion, the present study has, for the first time, clarified the risk factors of adrenal crisis. Among them, sex hormone deficiency has an especially important implication because it can be treated by hormone replacement therapy with the hope of reducing the risk of adrenal crisis.

Adolescent↗

PubMed2003

Lumbar drain.

Explore the source record for details and available documents.

Brain Diseases↗

PubMed2002

From epidemiology to physiology and pathology: apnea and arousal deficient theories in sudden infant death syndrome (SIDS)--with particular reference to hypoxic brainstem gliosis.

Among 27,000 infants studied prospectively to characterize their sleep-wake behavior, 38 infants died under 6 months of age. They included 26 cases of sudden infant death syndrome (SIDS). Five infants who died from congenital cardiac abnormalities, two from infected pulmonary dysplasia, two from septic shock with multi-organ failure, one during a prolonged seizure, one from a prolonged neonatal hypoxemia, one from meningitis with brain infarction. All the infants had been recorded during one night in a pediatric sleep laboratory some 3-12 weeks before death. The frequency and duration of sleep apneas were analyzed. The infants' brain stem material was collected and immunohistochemistry of glial fibrillary acidic protein (GFAP) was carried out. The density of GFAP-positive reactive astrocytes was measured in the cardiorespiratory and arousal pathway. Akaike information criterion statistics (AIC) were calculated to elucidate the relationship between the epidemiological data on sleep position, the physiological data and the pathological data in SIDS victims. The duration of obstructive apnea was the most significant variable to differentiate between SIDS victims and control infants. In conclusion, the present study sustains the possibility of an organic fragility within the arousal pathway in SIDS victims with repetitive sleep apneas.

Brain Stem↗

PubMed2002

From physiology to pathology: arousal deficiency theory in sudden infant death syndrome (SIDS)--with reference to apoptosis and neuronal plasticity.

Among 27,000 infants studied prospectively to characterize their sleep-wake behavior, 38 infants died under 6 months of age (including 26 infant victims of sudden infant death syndrome (SIDS), 5 with congenital cardiac abnormalities, 2 from infected pulmonary dysplasia, 2 from septic shock with multi-organ failure, 1 with a prolonged seizure, 1 from prolonged neonatal hypoxemia, 1 from meningitis and brain infarction). The frequency and duration of sleep apneas recorded some 3-12 weeks before the infants' death were analyzed. Brainstem material from these 38 infants was studied in an attempt to elucidate the relationship between sleep apnea and neuronal pathological changes in the arousal pathway. Immunohistochemical analyses included the evaluation of growth-associated phosphoprotein 43 (GAP43) as a marker for synaptic plasticity. The terminal-deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method was used to identify apoptosis. The positive pathological reactions were quantitatively analyzed. The pathological and physiological data were linked for each infant. Akaike Information Criterion (AIC) statistics was calculated to elucidate the relationship between the physiological and the pathological data in the SIDS victims. The findings illustrated the possibility of an organic fragility within the arousal pathway, particularly in the midbrain periaqueductal gray matter, which is associated with the "visceral alerting response". This autonomic response occurs within an acetylcholine afferent system and pedunculopontine tegmental nucleus (PPTN). The finding is, in future SIDS infants, associated with repetitive sleep apnea.

Apoptosis↗

PubMed2002

Association between sleep apnea and reactive astrocytes in brainstems of victims of SIDS and in control infants.

Among 27,000 infants studied prospectively to characterize their sleep-wake behavior, 38 infants died under 6 months of age; 27 infants died from sudden infant death syndrome (SIDS), 5 from congenital cardiac abnormalities, 2 from infected pulmonary dysplasia, 2 from septic shock with multi-organ failure, 1 with a prolonged seizure, and another with prolonged neonatal hypoxemia. The frequency and duration of sleep apneas recorded some 3-12 weeks prior to the infants' death were analyzed. Brainstem material was retrospectively collected from these 33 infants and studied in an attempt to elucidate the relationship between sleep apnea and hypoxic gliosis. The findings were compared between the SIDS victims and the control infants. Brainstem materials were immunohistochemically studied for quantitization of reactive astrocytes using an anti-glial fibrillary acidic protein (GFAP) antibody. The pathological materials were collected within 24h of death. This study focuses on the association between respiratory characteristics and pathology. Physiological and pathological data in the arousal pathway of the brainstem were linked for each infant and variant-covariant analyses were carried out using physiological data as dependent variables and pathological data and categorical data to evaluate the association with SIDS or non-SIDS as independent variables. The study failed to statistically support an association between hypoxic loads, reflected by the GFAP-positive reactive astrocytes in brainstems, the classification of being SIDS or non-SIDS infants, and the characteristics of sleep apnea.

Analysis of Variance↗

PubMed2002

Interaction between apnea, prone sleep position and gliosis in the brainstems of victims of SIDS.

Among 27,000 infants studied prospectively to characterize their sleep-wake behavior, 38 infants died suddenly and unexpectedly under 6 months of age. Of these, 26 died from sudden infant death syndrome (SIDS), 5 from congenital cardiac abnormalities, 2 from infected pulmonary dysplasia, 2 from septic shock with multi-organ failure, 1 from a prolonged seizure, 1 from prolonged neonatal hypoxemia, and 1 from meningitis and brain infarction. The frequency and duration of apneas recorded some 3-12 weeks prior to the infants' death were analyzed. The brainstem materials were collected and studied in an attempt to elucidate the relationship between sleep apnea, and prone sleep position and gliosis in some nuclei associated with cardiorespiratory characteristics, such as nucleus ambiguus in the medulla oblongata and the solitary nucleus, as well as structures associated with arousal phenomenon, such as the reticular formation, the superior central nucleus and the nucleus raphe magnus in the pons, the dorsal raphe nuclei in the midbrain and medulla oblongata, periaqueductal gray matter in midbrain, and locus ceruleus. Gliosis was estimated as the density of glial fibrillary acidic protein (GFAP)-positive reactive astrocytes. Variant-covariant analyses were carried out using the characteristics of apnea as an independent variable and sleep position and gliosis as dependent variables. A significant association was found only in the frequency of obstructive apnea and prone position (P<0.001) and gliosis in the raphe nuclei in the midbrain (P<0.001). Although prone position is a well-known risk factor for SIDS, the frequency of obstructive apnea has not been associated with the prone sleep position. The observed relation between prone sleep and the density of gliosis does not relate to epidemiological findings. Further studies are needed to investigate the unexpected statistical association.

Analysis of Variance↗

PubMed2002

Huge chronic subdural hematoma mimicking cerebral infarction on computed tomography--case report.

A 70-year-old male presented with progressive consciousness disturbance. He had a history of cerebrovascular accident in the left cerebral hemisphere. The initial diagnosis was newly developed extensive left cerebral hemispheric infarction based on computed tomography. However, magnetic resonance imaging and surgical findings were consistent with chronic subdural hematoma (CSDH). The preexisting neurological disease may have allowed such unexpected CSDH expansion.

Aged↗