Biomedical subjects

H Saegusa

Publications and source records attributed to H Saegusa.

At least 19 recordsLinked to original sources

PubMed2002

Actual behaviour of N-butyl-2-cyanoacrylate (histoacryl) in a blood vessel: a model of the varix.

BACKGROUND AND STUDY AIMS: Though many gastric varices are treated endoscopically with n-butyl-2-cyanoacrylate, its behavior in varices is not known precisely. MATERIALS AND METHODS: We created a varix model. A volume of 0.7 ml or 1.4 ml of 71.4 % n-butyl-2-cyanoacrylate, a tissue adhesive, was injected into vinyl tubes of 0.4, 0.6, 0.9, and 1.2 cm in diameter, which were filled with still blood or flowing blood. The tissue adhesive was also injected into the inferior vena cava or femoral vein of dogs. RESULTS: N-butyl-2-cyanoacrylate was similarly polymerized in the vinyl tubes and the animal veins. A volume of 0.7 ml of the tissue adhesive could block all tubes up to 0.6 cm in diameter. A double quantity of the tissue adhesive could block tubes 0.9 and 1.2 cm in diameter, with flow velocities up to 10 cm/s and up to 5 cm/s, respectively. Some polymer masses were fragmented. CONCLUSIONS: One rapid shot of the tissue adhesive can block a vessel 0.6 cm or less in diameter with fast flow velocity, and a vessel up to 1.2 cm in diameter with slow flow velocity. Fast blood flows in a larger diameter vessel and slow injection of the tissue adhesive may result in fragmentation. This model of the varix was useful for assessing the effect of tissue adhesive used to treat gastric varices.

Animals↗

PubMed2001

Mice lacking Ca(v)2.3 (alpha1E) calcium channel exhibit hyperglycemia.

To investigate the functional role of Ca(v)2.3 channel in glucose homeostasis, we performed in vivo glucose tolerance and insulin tolerance tests together with stress-induced glucose release tests using mice deficient in Ca(v)2.3 channel (Ca(v)2.3-/-). The Ca(v)2.3-/- mice were significantly heavier than wild-type mice. In glucose tolerance and insulin tolerance tests, Ca(v)2.3-/- mice showed a significantly higher blood glucose level compared to wild-type mice. However, stress-induced blood glucose changes in Ca(v)2.3-/- mice were similar to those in wild-type mice. These results suggest that Ca(v)2.3 channel plays a role in glucose homeostasis by reducing insulin sensitivity and that Ca(v)2.3-/- mice exhibit symptoms resembling non-insulin-dependent diabetes mellitus.

Animals↗

PubMed2001

Analysis of Ca(2+) currents in spermatocytes from mice lacking Ca(v)2.3 (alpha(1E)) Ca(2+) channel.

In mammalian male germ-line cells, low-voltage-activated (LVA) Ca(2+) current has been identified and its electrophysiological properties have been studied. To investigate whether alpha(1)2.3 (alpha(1E)) subunit of the voltage-dependent Ca(2+) channel codes for the LVA current, whole-cell patch clamp and following reverse transcription-polymerase chain reaction (RT-PCR) experiments were performed in pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice. Whole-cell current in acutely dissociated pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice displayed a typical profile of LVA Ca(2+) currents and kinetics with no significant differences. Single-cell RT-PCR revealed the expression of Cacna1g in the pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice in which LVA Ca(2+) currents were actually recorded. These results suggest that the Ca(v)2.3 channel makes no detectable contribution to the LVA Ca(2+) current in the pachytene spermatocyte. Instead, Ca(v)3 family such as Ca(v)3.1 may be the likely candidates responsible for the LVA currents in pachytene spermatocytes.

Animals↗

PubMed2001

Suppression of inflammatory and neuropathic pain symptoms in mice lacking the N-type Ca2+ channel.

The importance of voltage-dependent Ca2+ channels (VDCCs) in pain transmission has been noticed gradually, as several VDCC blockers have been shown to be effective in inhibiting this process. In particular, the N-type VDCC has attracted attention, because inhibitors of this channel are effective in various aspects of pain-related phenomena. To understand the genuine contribution of the N-type VDCC to the pain transmission system, we generated mice deficient in this channel by gene targeting. We report here that mice lacking N-type VDCCs show suppressed responses to a painful stimulus that induces inflammation and show markedly reduced symptoms of neuropathic pain, which is caused by nerve injury and is known to be difficult to treat by currently available therapeutic methods. This finding clearly demonstrates that the N-type VDCC is essential for development of neuropathic pain and, therefore, controlling the activity of this channel can be of great importance for the management of neuropathic pain.

Acetic Acid↗

PubMed2001

Intact LTP and fear memory but impaired spatial memory in mice lacking Ca(v)2.3 (alpha(IE)) channel.

To investigate the functional roles of the Ca(v)2.3 (alpha(1E)) channel in hippocampal CA1 pyramidal neurons, we studied in vitro synaptic properties and in vivo behaviors of the Ca(v)2.3 gene deficient mice. The Ca(v)2.3 channel mRNA was identified in the hippocampal formation of the wild-type mouse by in situ hybridization. The basic excitatory synaptic transmission and long-term potentiation by theta-burst stimulation were intact in CA1 region of Ca(v)2.3-/- mice. We performed two forms of behavioral tests to examine the hippocampus-dependent function, i.e., emotional and spatial learning tests. The Ca(v)2.3-/- mice were able to establish and maintain fear memories. Although general improvement in the performance of Morris water maze test was seen in Ca(v)2.3-/- mice, they displayed an obvious impairment in the probe test. These results suggest that the Ca(v)2.3 channel plays some role in formation of the accurate spatial memory but not of the fear memory.

Animals↗

PubMed2001

Close relationship of tissue plasminogen activator-plasminogen activator inhibitor-1 complex with multiple organ dysfunction syndrome investigated by means of the artificial pancreas.

BACKGROUND: Glucose tolerance (GT) has not been taken into consideration in investigations concerning relationships between coagulopathy and multiple organ dysfunction syndrome (MODS), and endothelial cell activation/endothelial cell injury (ECA/ECI) in septic patients, although coagulopathy is known to be influenced by blood glucose level. We investigated those relationships under strict blood glucose control and evaluation of GT with the glucose clamp method by means of the artificial pancreas in nine septic patients with glucose intolerance. The relationships between GT and blood stress related hormone levels (SRH) were also investigated. METHODS: The amount of metabolized glucose (M value), as the parameter of GT, was measured by the euglycemic hyperinsulinemic glucose clamp method, in which the blood glucose level was clamped at 80 mg/dl under a continuous insulin infusion rate of 1.12 mU/kg per min, using the artificial pancreas, STG-22. Multiple organ failure (MOF) score was calculated using the MOF criteria of Japanese Association for Critical Care Medicine. Regarding coagulopathy, the following parameters were used: disseminated intravascular coagulation (DIC) score (calculated from the DIC criteria of the Ministry of Health and Welfare of Japan) and the parameters used for calculating DIC score, protein-C, protein-S, plasminogen, antithrombin III (AT-III), plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator-PAI-1 (tPA-PAI-1) complex. Thrombomodulin (TM) was measured as the indicator of ECI. RESULTS: There were no significant correlations between M value and SRH, parameters indicating coagulopathy and the MOF score. The MOF score and blood TM levels were positively correlated with DIC score, thrombin-AT-III complex and tPA-PAI-1 complex, and negatively correlated with blood platelet count. CONCLUSIONS: GT was not significantly related to SRH, coagulopathy and MODS under strict blood glucose control. Hypercoagulability was closely related to MODS and ECI. Among the parameters indicating coagulopathy, tPA-PAI-1 complex, which is considered to originate from ECA, seemed to be a sensitive parameter of MODS and ECI, and might be a predictive marker of MODS. The treatment for reducing hypercoagulability and ECA/ECI were thought to be justified as one of the therapies for acutely ill septic patients.

Blood Coagulation Disorders↗

PubMed2001

Cloning of an intracellular Poly[D(-)-3-Hydroxybutyrate] depolymerase gene from Ralstonia eutropha H16 and characterization of the gene product.

An intracellular poly[D(-)-3-hydroxybutyrate] (PHB) depolymerase gene (phaZ) has been cloned from Ralstonia eutropha H16 by the shotgun method, sequenced, and characterized. Nucleotide sequence analysis of a 2.3-kbp DNA fragment revealed an open reading frame of 1,260 bp, encoding a protein of 419 amino acids with a predicted molecular mass of 47,316 Da. The crude extract of Escherichia coli containing the PHB depolymerase gene digested artificial amorphous PHB granules and released mainly oligomeric D(-)-3-hydroxybutyrate, with some monomer. The gene product did not hydrolyze crystalline PHB or freeze-dried artificial amorphous PHB granules. The deduced amino acid sequence lacked sequence corresponding to a classical lipase box, Gly-X-Ser-X-Gly. The gene product was expressed in R. eutropha cells concomitant with the synthesis of PHB and localized in PHB granules. Although a mutant of R. eutropha whose phaZ gene was disrupted showed a higher PHB content compared to the wild type in a nutrient-rich medium, it accumulated PHB as much as the wild type did in a nitrogen-free, carbon-rich medium. These results indicate that the cloned phaZ gene encodes an intracellular PHB depolymerase in R. eutropha.

Amino Acid Sequence↗

PubMed2000

Altered pain responses in mice lacking alpha 1E subunit of the voltage-dependent Ca2+ channel.

alpha(1) subunit of the voltage-dependent Ca(2+) channel is essential for channel function and determines the functional specificity of various channel types. alpha(1E) subunit was originally identified as a neuron-specific one, but the physiological function of the Ca(2+) channel containing this subunit (alpha(1E) Ca(2+) channel) was not clear compared with other types of Ca(2+) channels because of the limited availability of specific blockers. To clarify the physiological roles of the alpha(1E) Ca(2+) channel, we have generated alpha(1E) mutant (alpha(1E)-/-) mice by gene targeting. The lacZ gene was inserted in-frame and used as a marker for alpha(1E) subunit expression. alpha(1E)-/- mice showed reduced spontaneous locomotor activities and signs of timidness, but other general behaviors were apparently normal. As involvement of alpha(1E) in pain transmission was suggested by localization analyses with 5-bromo-4-chloro-3-indolyl beta-d-galactopyranoside staining, we conducted several pain-related behavioral tests using the mutant mice. Although alpha(1E)+/- and alpha(1E)-/- mice exhibited normal pain behaviors against acute mechanical, thermal, and chemical stimuli, they both showed reduced responses to somatic inflammatory pain. alpha(1E)+/- mice showed reduced response to visceral inflammatory pain, whereas alpha(1E)-/- mice showed apparently normal response compared with that of wild-type mice. Furthermore, alpha(1E)-/- mice that had been presensitized with a visceral noxious conditioning stimulus showed increased responses to a somatic inflammatory pain, in marked contrast with the wild-type mice in which long-lasting effects of descending antinociceptive pathway were predominant. These results suggest that the alpha(1E) Ca(2 +) channel controls pain behaviors by both spinal and supraspinal mechanisms.

Acetic Acid↗

PubMed2000

Spinocerebellar ataxia type 6 mutation alters P-type calcium channel function.

Abnormal CAG repeat expansion in the alpha1A voltage-dependent calcium channel gene is associated with spinocerebellar ataxia type 6, an autosomal dominant cerebellar ataxia with a predominant loss of the Purkinje cell. A reverse transcriptase-polymerase chain reaction analysis of mRNA from mouse Purkinje cells revealed a predominant expression of the alpha1A channel lacking an asparagine-proline (NP) stretch in the domain IV (alpha1A(-NP)). Human alpha1A channels carrying various polyglutamine length with or without NP were expressed in HEK293 cells, and channel properties were compared using a whole-cell voltage clamp technique. alpha1A(-NP), corresponding to P-type channel, with 24 and 28 polyglutamines found in patients showed the voltage dependence of inactivation shifting negatively by 6 and 11 mV, respectively, from the 13 polyglutamine control. Contrarily, the alpha1A channel with NP (alpha1A(+NP)), corresponding to Q-type channel, with 28 polyglutamines exhibited a positive shift of 5 mV. These results suggest that altered function of alpha1A(-NP) may contribute to degeneration of Purkinje cells, which express predominantly alpha1A(-NP), due to the reduced Ca(2+) influx resulting from the negative shift of voltage-dependent inactivation. On the other hand, other types of neurons, expressing both alpha1A(-NP) and alpha1A(+NP), may survive because the positive shift of voltage-dependent inactivation of alpha1A(+NP) compensates Ca(2+) influx.

Animals↗

PubMed2000

Glucose stimulates the release of bombyxin, an insulin-related peptide of the silkworm Bombyx mori.

The effects of starvation and feeding on the release of bombyxin, a peptide of insulin superfamily in insects, from the larval brain of the silkworm Bombyx mori were investigated. Following starvation, the bombyxin titer in the hemolymph of larvae decreased, whereas its content in the brain increased. On the other hand, refeeding of the starved larvae resulted in an increase in the hemolymph bombyxin titer and a rapid decrease in the hormone level in the brain. These results indicate that the release of bombyxin from the brain is suppressed by starvation and stimulated by feeding. The hemolymph glucose titer also changed sharply upon starvation and refeeding, and a close relationship was observed between the changes in glucose concentrations and bombyxin titers in the hemolymph. The injection of glucose into starved larvae could mimic the effect of refeeding on the release of bombyxin, suggesting that glucose serves as the signal for the "fed" state of the animal. It is likely that glucose is a common nutritional signal for inducing the release of mammalian and insect insulins.

Animals↗

PubMed2000

Effects of spironolactone on systolic blood pressure in experimental diabetic rats.

BACKGROUND: Mineralocorticoid hormones, which maintain electrolyte balance and blood pressure, are thought to be associated not only with the expression of renal 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), but also with that of intracellular mineralocorticoid receptors (MRs). The present study was designed to test whether the mineralocorticoid action of glucocorticoid corticosterone on renal MR is involved in the development of diabetes-associated hypertension by measuring the alterations of renal 11beta-HSD2. METHOD: We measured the mean systolic blood pressure, renal 11beta-HSD1, and mRNA levels in streptozotocin (STZ)-induced diabetic rats that received spironolactone, insulin, or no treatment, and in nondiabetic controls that received spironolactone. RESULTS: Four weeks after an injection of STZ, the renal 11beta-HSD2 and mRNA levels were significantly lower in diabetic rats than in control rats, and the mean systolic blood pressure was 14.8% higher in diabetic rats than in controls. Subcutaneous injections of spironolactone into diabetic rats for three weeks partially reversed the decrease in renal 11beta-HSD2 activity and gene expression, and prevented the mean systolic blood pressure elevation. Spironolactone treatment for one week also resulted in a significant reduction in mean systolic blood pressure during the development of diabetic hypertension. However, treatment with STZ did not significantly decrease the renal 11beta-HSD1 activity and mRNA expression, and spironolactone treatment did not exert a significant effect on this enzyme in STZ-induced diabetic rats. CONCLUSION: In the development of diabetes-induced hypertension, the effect of spironolactone on mean systolic blood pressure may be associated with the mineralocorticoid effects of corticosterone on renal MR, as well as an alteration of renal 11beta-HSD2 activity and its mRNA expression in insulin-dependent diabetic rats.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1999

Influence of placental 11beta-hydroxysteroid dehydrogenase (11beta-HSD) inhibition on glucose metabolism and 11beta-HSD regulation in adult offspring of rats.

Placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) converts glucocorticoids to 11-keto-products and is believed to play an important role in protecting fetuses from higher maternal glucocorticoid levels. Recent reports have speculated that prenatal glucocorticoid exposure leads to fetal growth retardation and adult offspring hypertension and hyperglycemia. To investigate the effects of placental 11beta-HSD2 inhibition on glucose metabolism and the 11beta-HSD system in adult offspring, pregnant rats were treated with daily injections of carbenoxolone (CBX), an inhibitor of 11beta-HSD. The offspring of the maternal CBX treatment group showed reduced birth weight (treated v control, 5.6 +/- 0.5 v 6.4 +/- 0.4 g, P < .0001). In adult offspring of the maternal CBX treatment group, plasma hemoglobin A1c was significantly increased (7.3% +/- 1.8% v 4.8% +/- 0.3%, P < .01) and glucose intolerance was shown on the oral glucose tolerance test. The gene expression of hepatic 11beta-HSD1 and renal 11beta-HSD2 was decreased 87.6% (P < .05) and 52.3% (P < .01) in adult offspring of the maternal CBX treatment group, whereas renal 11beta-HSD1 was not significantly altered. The change in 11beta-HSD activity corresponded to the change in the gene expression. These results suggest that inhibition of placental 11beta-HSD2 causes growth retardation, glucose intolerance, and partial suppression of the 11beta-HSD system in the offspring.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1999

Abundant expression and cytoplasmic aggregations of [alpha]1A voltage-dependent calcium channel protein associated with neurodegeneration in spinocerebellar ataxia type 6.

Spinocerebellar ataxia type 6 (SCA6) is one of the eight neurodegenerative diseases caused by a tri-nucleotide (CAG) repeat expansion coding polyglutamine (CAG repeat/polyglutamine diseases) and is characterized by late onset autosomal dominant cerebellar ataxia and predominant loss of cerebellar Purkinje cells. Although the causative, small and stable CAG repeat expansion for this disease has been identified in the [alpha]1A voltage-dependent calcium channel gene (CACNA1A), the mechanism which leads to predominant Purkinje cell degeneration is totally unknown. In this study, we show that the calcium channel mRNA/protein containing the CAG repeat/polyglutamine tract is most intensely expressed in Purkinje cells of human brains. In SCA6 brains, numerous oval or rod-shaped aggregates were seen exclusively in the cytoplasm of Purkinje cells. These cytoplasmic inclusions were not ubiquitinated, which contrasts with the neuronal intra-nuclear inclusions of other CAG repeat/polyglutamine diseases. In cultured cells, formation of perinuclear aggregates of the channel protein and apoptotic cell death were seen when transfected with full-length CACNA1A coding an expanded polyglutamine tract. The present study indicates that the mechanism of neurodegeneration in SCA6 is associated with cytoplasmic aggregations of the [alpha]1A calcium channel protein caused by a small CAG repeat/polyglutamine expansion in CACNA1A.

Animals↗

PubMed1999

[Artificial graft replacement increases the speed of the pulse wave velocity along the aorta].

We investigated the change in the pulse wave velocity along the aorta after a part of the vessel was replaced by artificial graft in seven patients. Graft-replacement was performed under general or general combined with epidural anesthesia. The velocity measurement was performed in a standard manner before and after the surgical procedure. The replacement by artificial graft consistently increased the pulse wave velocity of which the means +/- SD were 10.4 +/- 2.4 m.s-1 before the surgery, and 13.3 +/- 3.6 m.s-1 after the surgery, amounting a 26.9 per cent increase. The change was statistically significant. The range of this increase was between 8.9% and 45.7%. No changes were observed in various hemodynamic parameters and hematocrits, except the heart rate which increased from 57.4 to 69.1 +/- 9.0 bpm. We conclude that the speed of the pulse wave velocity along the aorta increases markedly by artificial graft replacement. We propose this change is caused by a marked stiffness of the material of the artificial graft. The exact mechanism, however, remains to be elucidated.

Aged↗

PubMed1998

Effects of thyroid hormone (thyroxine) and testosterone on hepatic 11beta-hydroxysteroid dehydrogenase mRNA and activity in pubertal hypothyroid male rats.

To investigate the effects of thyroid hormone and testosterone on 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), we measured changes in hepatic 11beta-dehydrogenase activity and its mRNA levels in pubertal methimazole (MMI)-induced hypothyroid male rats following treatment with thyroxine ([T4] 50 microg/kg/d) or testosterone (250 microg/d) for 14 days. Hypothyroidism in male rats markedly reduced hepatic 11beta-HSD1 mRNA levels and serum testosterone concentrations (P < .01). Subcutaneous injection of T4 in the hypothyroid rats significantly (P < .01) increased hepatic 11beta-HSD1 mRNA to approximately normal levels and simultaneously increased serum testosterone levels. However, the same daily dose of T4 administered to castrated male hypothyroid rats for 14 days did not elevate hepatic 11beta-HSD1 activity. Treatment with testosterone for 14 days in castrated hypothyroid male rats and rats without gonadectomy significantly (P < .01) increased the enzyme activity without administration of T4. Variations in hepatic 11beta-HSD1 activity were demonstrated to be accompanied by changes in serum testosterone levels in the rats following alteration of the thyroid hormone state. These results suggest that the effect of T4 in increasing the subnormal 11beta-HSD1 gene expression in hypothyroid male rats is mediated by its ability to increase testosterone production in these rats, because in castrated hypothyroid rats, T4 does not elevate 11beta-HSD1 gene expression.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1998

Preoperative superselective embolization of skull-base meningiomas: indications and limitations.

We evaluated the clinical significance of preoperative superselective embolization for skull-base meningiomas. The subjects consisted of 20 patients with skull-base meningiomas, and were classified into a preoperative embolized group and a non-embolized group. The volume of blood transfused during the operation, the length of the operative procedure and the neurological outcome were compared between the two groups. The results showed that, in tumors smaller than 6 cm, the blood lost during the operation was significantly less in the embolized group. In tumors larger than 6 cm, there was not difference in blood lost, perhaps because larger meningiomas tend to have tiny blood vessels that are unsuitable for preoperative embolization. There was no difference in the length of the operation between the two groups. The embolized group tended to show a better clinical outcome than the non-embolized group.

Adult↗

PubMed1998

Sequence and expression of a novel mouse gene PRDC (protein related to DAN and cerberus) identified by a gene trap approach.

Gene trapping in embryonic stem (ES) cells was used to identify a novel gene involved in mouse development. In order to screen trapped ES cell lines for the presence of developmentally regulated genes, an in vitro differentiation test was used. One of the G418 resistant cell lines, in conjunction with the lacZ reporter gene, showed differential expression patterns under differentiated and undifferentiated conditions. The gene trap insertion in this cell line was germ-line transmitted and X-gal staining was used to assess the expression pattern of lacZ in embryos heterozygous for the trapped allele. The reporter gene's expression was detected in commissural neurons in the developing spinal cord, suggesting functions for the trapped gene in mouse neural development. Structural analysis of the cDNA revealed that this trapped gene, named PRDC (protein related to DAN and cerberus), is a novel gene that encodes a putative secretory protein consisting of 168 amino acid residues. PRDC gene product shows limited similarities to the products of DAN (differential screening-selected gene aberrative in neuroblastoma) and cerberus. (DAN is a possible tumor-suppressor for neuroblastoma in human. Cerberus can induce an ectopic head in Xenopus embryos when ectopically expressed.) These three gene products may form a novel family of signaling molecules.

Alleles↗

PubMed1998

Juvenile symptomatic Rathke's cleft cyst--case report.

A 14-year-old girl presented with a rare symptomatic Rathke's cleft cyst manifesting as diabetes insipidus and growth retardation. Neuroimaging demonstrated the suprasellar cyst. Computed tomography showed the cyst as an isodense area with enhancement, and magnetic resonance imaging showed an hyperintense area on both T1- and T2-weighted images. Histological examination showed the cyst was consistent with Rathke's cleft cyst. Symptomatic Rathke's cleft cysts usually occur in middle-aged adults. Juvenile cases tend to present with diabetes insipidus, and the cyst content may include more mucopolysaccharides or hemosiderin degradation products.

Adolescent↗