Biomedical subjects

C Sasaki

Publications and source records attributed to C Sasaki.

At least 19 recordsLinked to original sources

PubMed2003

Comparison between tube compensation and pressure support ventilation techniques on respiratory mechanics.

In the intubated patient, the presence of an endotracheal tube increases the work of breathing during spontaneous breathing. The tube compensation technique was developed as a new ventilator mode that can compensate for that additional the work of breathing. We investigated the respiratory parameters during the pressure support ventilation 0, 5, 10 cmH2O and tube compensation 100% modes of the Puritan Bennett 840 ventilator in ten postoperative patients who had undergone radical surgery for oesophageal cancer. Measurements were performed just before extubation. The tidal volume, respiratory rate and other respiratory parameters were measured with a Ventrak respiratory monitor, and the duty ratio, mean inspiratory flow, and rapid shallow breathing index were calculated. In particular, we performed a comparison between pressure support ventilation 5 cmH2O and tube compensation 100%, because pressure support ventilation 5 cmH2O is the usual ventilating mode before the extubation in our intensive care unit. The tidal volume of pressure support ventilation 10 cmH2O was significantly larger and the respiratory rate was significantly lower than the other three modes. There was no significant difference in the minute volume, tidal volume, and respiratory rate between pressure support ventilation 5 cmH2O and tube compensation 100%. The duty ratio of pressure support ventilation 10 cmH2O was significantly smaller than the other three modes. There was no significant difference in the duty ratio and rapid shallow breathing index between pressure support ventilation 5 cmH2O and tube compensation 100%. It was concluded that the assist levels of pressure support ventilation 5 cmH2O and tube compensation 100% were almost equal for clinical purposes.

Aged↗

PubMed2002

A case of paroxysmal kinesigenic dyskinesia with spastic paraparesis.

We report the first case of paroxysmal kinesigenic dyskinesia (PKD) with spastic paraparesis. A 17-year-old male began to show a dystonic posture in both his upper limbs when walking at age 12 years. Neurological examination revealed bilateral talipes cavus, spasticity in all extremities with general hyperreflexia and pathological reflexes. On starting to walk, he showed a dystonic posture in bilateral maniphalanx, wrists, elbows, and toes. Magnetic resonance imaging (MRI) revealed high T2-weighted signal intensity in bilateral pyramidal tract. Although the combination of pyramidal and the basal ganglia disorders is very rare, the present case suggests an inter-relation of the pyramidal and the basal ganglia systems.

Adolescent↗

PubMed2001

Temporal and spatial differences of PSA-NCAM expression between young-adult and aged rats in normal and ischemic brains.

Highly polysialylated neural cell adhesion molecule (PSA-NCAM) is transiently expressed specifically in newly generated cells, and is important for migration and neurite outgrowth. To investigate the effect of aging on the migration of neural stem cell (NSC) after brain ischemia, the spatiotemporal expressions of immunoreactive PSA-NCAM were examined at 4 h or 1, 3 or 7 days after 90 min of middle cerebral artery occlusion (MCAO) in the young-adult or aged rats. In the sham control brain, PSA-NCAM staining was slightly observed both in dorsal and ventral parts of subventricular zone (SVZ) in the aged brain, but only in the dorsal part of SVZ in the young brain. After transient MCAO, immunoreactivity for PSA-NCAM increased in the number and the intensity in SVZ ipsilateral to MCAO in the young-adult brains and became the peak at 1 day, while that was at 3 days in the aged brains. These findings suggest that PSA-NCAM was located in different spatial distribution in normal condition between young and old rats. PSA-NCAM was induced after ischemia, and the temporal expression was also different after transient MCAO between young and older rats.

Aging↗

PubMed2001

Role of hydrophilic interaction in binding of hydroxylated 3-deoxy C(19) steroids to the active site of aromatase.

As part of our investigation into the structure-activity relationship of a novel class of aromatase inhibitors, C(19) steroids having no oxygen function at C-3, we tested aromatase inhibition activity of polar diol compounds 4,19-dihydroxyandrost-5-en-17-ones (25 and 27) and 6,19-dihydroxyandrost-4-en-17-ones (36 and 37). 4alpha,19-Diol 25 was synthesized from tert-butyldimethylsilyoxyandrost-4-ene steroid (9) through its OsO(4) oxidation, giving the 4alpha,5alpha-dihydroxy derivative 12, as a key reaction. Acetylation of 5beta,6alpha-dihydroxy-19-acetate 30 and its 5alpha,6beta-analogue 31 followed by dehydration with SOCl(2) and alkaline hydroxysis gave 6alpha,19-diol 36 and its 6beta-isomer 37, respectively. The stereochemistry of a hydroxy group at C-4 of compound 25 and that at C-6 of compounds 36 and 37 were determined on the basis of (1)H NMR spectroscopy in each case. 4beta,19-Diol 27, previously synthesized, was identified as an extremely powerful competitive inhibitor of aromatase (K(i) = 3.4 nM). In contrast, its 4alpha,19-dihydroxy isomer 25 and other series of diol compounds, 6,19-dihydroxy-4-en-17-one steroids, were moderate to poor competitive inhibitors (K(i) = 110-800 nM). Through this series of analyses, it was concluded that hydrophilic interaction of a 4beta,19-diol function with the active site of aromatase plays a critical role in the tight binding of 3-deoxy-5-ene steroids.

Androstenediols↗

PubMed2001

Kinetic properties of chitinase-1 from the fungal pathogen Coccidioides immitis.

The endochitinase from Coccidioides immitis (CiX1) is a member of the class 18 chitinase family. Here we show the enzyme functions by a retaining catalytic mechanism; that is, the beta-conformation of the chitin substrate linkages is preserved after hydrolysis. The pattern of cleavage of N-acetyglucosamine (GlcNAc) oligosaccharide substrates has been determined. (GlcNAc)6 is predominantly cleaved into (GlcNAc)2 and (GlcNAc)4, where the (GlcNAc)2 group arises from the nonreducing end of the substrate and is formed as the beta-anomer. With time, transglycosylation occurs, generating (GlcNAc)8 from the product dimer and fresh hexamer. Similar patterns are seen for the cleavage of (GlcNAc)5 and (GlcNAc)4 where dimers cleaved from the nonreducing end reflect the most common binding and hydrolysis pattern. Intrinsic fluorescence measurements suggest the dissociation constant for (GlcNAc)4 is 50 microM. Synthetic substrates with fluorescent leaving groups exhibit complicated profiles in the relationship between initial velocity and substrate concentration, making it difficult to obtain the values of kinetic constants. An improved theoretical analysis of the time-course of (GlcNAc)6 degradation allows the unitary free energy of binding of the individual subsites of the enzyme to be estimated. The free energy values obtained are consistent with the dissociation constant obtained by fluorescence measurements, and generate a model of substrate interaction that can be tested against the crystal structure of the enzyme.

Acetylglucosamine↗

PubMed2001

Apoptosis in regressive deciduous tooth germs of Suncus murinus evaluated by the the TUNEL method and electron microscopy.

Apoptosis in regressive primary (deciduous) dental primordia was examined in the embryos of Suncus murinus, which is a monophyodont. The primary tooth germs of S. murinus are temporarily formed and disappear during the embryonic period before they are calcified. Most primary tooth germs reach the bell stage and degenerate by embryonic day 22 (E22). Light microscopy on haematoxylin-eosin-stained sections revealed that intensely labelled granular substances are frequently present in the epithelial portion (enamel organs) of the deciduous tooth germs during the period from E18 to E20. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labelling method, computer-assisted three-dimensional reconstructions, and electron microscopy confirmed that these variable-sized granular substances are similar to apoptotic cells or bodies. Apoptotic structures were mainly found in the primary tooth germ located on the buccal surface of the secondary (successional) tooth germ. These results lead to the conclusion that apoptosis is closely associated with the involution and disappearance of the deciduous tooth germ in S. murinus. A primary tooth germ was observed on the buccal side of all the corresponding successional tooth germs, although the buccal surface of the secondary tooth germ of third upper molar teeth developed only to epithelial thickening without mesenchymal condensation. The findings, therefore, suggest that apoptosis is responsible for disappearance of the primary dental primordia during tooth development in S. murinus.

Animals↗

PubMed2001

Attenuation of oxidative DNA damage with a novel antioxidant EPC-K1 in rat brain neuronal cells after transient middle cerebral artery occlusion.

EPC-K1, L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-yl-hydrogen phosphate] potassium salt, is a novel antioxidant. In this study, we investigated a reduction of oxidative neuronal cell damage with EPC-K1 by immunohistochemical analysis for 8-hydroxy-2'-deoxyguanosine (8-OHdG) in rat brain with 60 min transient middle cerebral artery occlusion, in association with terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) and staining for total and active caspase-3. Treatment with EPC-K1 (20 mg kg(-1) i.v.) significantly reduced infarct size (p < 0.05) at 24 h of reperfusion. There were no positive cells for 8-OHdG and TUNEL in sham-operated brain, but numerous cells became positive for 8-OHdG, TUNEL and caspase-3 in the brains with ischemia. The number was markedly reduced in the EPC-K1 treated group. These reductions were particularly evident in the border zone of the infarct area, but the degree of reduction was less in caspase-3 staining than in 8-OHdG and TUNEL stainings. These results indicate EPC-K1 attenuates oxidative neuronal cell damage and prevents neuronal cell death.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

Different expression of glycogen synthase kinase-3beta between young and old rat brains after transient middle cerebral artery occlusion.

Ischemia is a common stress to human brain and is difficult to cure in older individuals. To examine the differences of the response to cerebral ischemia between young and old rat brains, distributions of glycogen synthase kinase-3beta (GSK3beta) and tau proteins were analyzed after 90 min of transient middle cerebral artery occlusion (MCAO) in young (10-11 weeks) and old (15 months) rats by immunohistochemical analyses. At 4 h of reperfusion, strong cytoplasmic and nuclear immunoreactivity for GSK3beta was induced in neurons of lamina I, II, V and VI of the cerebral cortex and dorsal caudate in young brains, while the induction was not observed in lamina I and II of old cerebral cortex. The staining in lamina V and VI and dorsal caudate then gradually decreased until seven days of reperfusion in both animal groups. The staining of tau protein and terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) did not show any positive signals in the control brain, but showed positive signals after ischemia with a peak at 24 h and 3 days, respectively. No significant difference was observed in the temporal and spatial patterns of tau and TUNEL stainings between these two groups. These data suggest that GSK3beta may have a role in ischemic neuronal cell death, and that the different spatial expression of GSK3beta between young and old rat brains may partly explain the vulnerability of older neurons after ischemia.

Aging↗

PubMed2001

Induction of PML immunoreactivity in rat brain neurons after transient middle cerebral artery occlusion.

Promyelocytic leukemia (PML) protein is involved in apoptotic death of cultured neuronal cells, but its role in ischemic brain damage remains uncertain. In this study, we investigated change of immunoreactivity for PML protein in rat brain after transient middle cerebral artery occlusion, and compared the results with that of terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL). Western blotting analysis revealed that PML immunoreactivity was only scant in the sham-control brain, but it increased at 1 h and 1 day after reperfusion, and decreased in density thereafter. Immunohistochemical analysis revealed that nuclei of neurons were most densely stained. TUNEL positive cells appeared at 1 day and peaked at 3 days of reperfusion, indicating that PML protein induction preceded DNA fragmentation in neurons. The present results suggest that PML protein may be one of the key molecules in ischemic neuronal cell death.

Animals↗

PubMed2001

Evaluation of tube compensation in the Bennett 840 ventilator--a new ventilatory mode to support spontaneous breathing.

Respiratory care patients frequently require intubation with an endotracheal tube (ETT). Unfortunately, the ETT introduces a pressure drop (deltaPETT) that depends on the respiratory flow rate, thus increasing the work of breathing (WOB). Pressure support ventilation (PSV) cannot adequately compensate for this added WOB, because the degree of inspiratory assistance by PSV is fixed. Therefore, a technique called tube compensation (TC) has been developed to address deltaPETT. We examined the performance of TC and compared it with PSV of 5 cm H2O. The experimental system was constructed from a simulator, a test-lung, flow sensors, and a Bennett 840, and the respiratory parameters were studied. ETTs with IDs 6.5 and 8.0 mm were used. The quadratic approximation obtained for deltaPETT in the 6.5-mm ETT was 2.316 x flow + 7.910 x flow2, while that for the 8.0-mm ETT was 1.881 x flow + 3.353 x flow2. The maximum inspiratory flow (MIF) increased significantly with increasing TC, but tidal volume and inspiratory time did not show marked changes. The MIF for TC of 100% was larger than that for PSV of 5 cm H2O, when the 6.5-mm ID was used, but there was no significant difference between these modes when an ID of 8.0 mm was used. For both the 6.5 and 8.0-mm IDs, the PV loop corresponding to 100% TC was larger than that for PSV of 5 cm H2O. TC only compensated for the WOB caused by the ETT, whereas PSV compensated for the WOB caused by the ETT and the demand valve system. In clinical use, the differences between TC and PSV will demand attention.

Humans↗

PubMed2000

Sjögren's syndrome with acute transverse myelopathy as the initial manifestation.

This is the first report of a patient with acute transverse myelopathy as the initial manifestation of primary Sjögren's syndrome (SS). The patient developed tetraparesis and sensory disturbance within 6 days of onset. Spinal MRI showed an extensive intraparenchymal lesion with high T2-weighted signal intensity, gadolinium enhancement, and cord swelling. Although the patient did not show clinical sicca symptoms, primary SS was diagnosed on the basis of clinical tests on lacrimal and salivary glands which showed high levels of autoantibodies. Treatment with prednisone improved motor and sensory symptoms and resulted in improvement of MRI findings. The present case suggests that acute transverse myelopathy can occur as an initial symptom of SS.

Aged↗

PubMed2000

c-Jun N-terminal kinase (JNK) and JNK interacting protein response in rat brain after transient middle cerebral artery occlusion.

c-Jun response is involved in the development of ischemic brain injury, which is activated by c-Jun N-terminal kinase-1 (JNK-1). The activity of JNK-1 is strictly regulated, and only the phosphorylated form of JNK (phospho-JNK) which is translocated to the nucleus has an ability to activate c-Jun response. There is a protein which inhibits JNK-1 activation, and known as JNK interacting protein-1 (JIP-1). In this study, we investigated change in JNK-1, phospho-JNK, and JIP-1 immunoreactivity in rat brain after transient middle cerebral artery (MCA) occlusion. Immunoreactive JNK-1 was scant in the sham-control brain, but it was induced at 1 h after reperfusion, which was slightly increased at 3 h of reperfusion. By contrast, phospho-JNK remained negative till 3 h. At 8 h, JNK-1 and phospho-JNK became distinctly positive, and nuclei as well as cytoplasm were stained. Thereafter, immunoreactivity for JNK-1 and phospho-JNK became furthermore dense, and most neurons revealed positively stained nuclei. Immunoreactivity for JIP-1 remained negative till 8 h of reperfusion, but at 24 and 72 h, cytoplasm of cortical neurons at the MCA boundary area was positively stained. This JIP-1 induction got behind the JNK-1 activation, and therefore, may be a vain effort for neurons to survive. Inhibition of JNK-1 activation might become an innovative means of therapy for stroke treatment in the future.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Loss of bag-1 immunoreactivity in rat brain after transient middle cerebral artery occlusion.

Although bag-1 is a strong apoptosis repressor protein, its functions in normal or injured brains are not fully understood. In the present study, we investigated expression of bag-1 protein in rat brain after transient middle cerebral artery (MCA) occlusion, and compared the results with that of terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling (TUNEL). Immunohistochemical analysis revealed that neuronal, choroid plexus, and ependymal cells were positively stained in the sham control brain. After 90 min of transient MCA occlusion, immunoreactivity for bag-1 progressively decreased from 3 to 48 h in the nuclei of neurons. Western blot analysis revealed that immunoreactive bag-1 was markedly decreased in the nuclear fraction. In contrast, cytosolic and mitochondrial fractions showed no or only slight change after the ischemia. TUNEL positive cells appeared at 48 h after the reperfusion, which was preceded by loss of bag-1 immunoreactivity. The present results suggest that bag-1 plays some roles in normal neuronal function, and its loss may be involved in neuronal cell death after ischemia.

Animals↗

PubMed2000

Phosphorylation of retinoblastoma protein in rat brain after transient middle cerebral artery occlusion.

Although mature neurones do not replicate genomic DNA, some cell cycle-related kinases are aberrantly activated in neurones after ischaemia. As hyper-phosphorylation of retinoblastoma (Rb) protein is the common pathway in mitotic signal cascade, this study investigated the phosphorylation state of the Rb protein as well as its mRNA level in rat brain after transient middle cerebral artery (MCA) occlusion. Immunohisto-chemical analysis revealed that neurones in the sham-operated brain expressed Rb protein without the hyperphosphorylated form. Immunoreactivity for the hyperphosphorylated form of Rb protein progressively increased from 1 h to 3 days after ischaemia in neurones in the MCA territory. Western blot analysis demonstrated a similar change. However, reverse transcription-polymerase chain reaction study revealed that Rb showed no definite change at the mRNA level. These results suggest that Rb protein is progressively hyper-phosphorylated in the brain after ischaemia, which may activate apoptotic mechanisms in neuronal cells of the brain after ischaemia.

Animals↗

PubMed2000

Protective effect of ginkgo extract on rat brain with transient middle cerebral artery occlusion.

It has been empirically known that Ginkgo extract is useful for reducing many symptoms associated with cerebral blood flow (CBF) insufficiency, but its mechanisms have been uncertain. In the present study, therefore, we gave Ginkgo extract to rats with per os digestion, and investigated its effect on CBF and ischemic brain damage with middle cerebral artery occlusion (MCAO). The treatment with Ginkgo extract (10 mg 100 g-1 rat) increased CBF in the normal condition, but the degree of increase in CBF was lesser during and after MCAO. TTC staining showed that infarct volume was reduced with Ginkgo treatment. TUNEL and HSP72 immunostaining confirmed the protective effect of Ginkgo treatment reducing numbers of TUNEL and HSP72 positive cells. Immunohistochemical analysis showed that caspase-3 expression was less abundant in Ginkgo treated rats. The present results suggest that Ginkgo extract contains a substance which increases normal CBF and reduces ischemic brain damage.

Animals↗

PubMed2000

Temporal profile of cytochrome c and caspase-3 immunoreactivities and TUNEL staining after permanent middle cerebral artery occlusion in rats.

Although apoptotic pathways play important roles in ischemic neuronal injury, exact mechanism of apoptotic enzyme cascade has not been fully studied. Immunohistochemical stainings for cytochrome c and caspase-3, and histochemical staining for a terminal deoxynucleotidyl-transferase (TdT)-mediated dUTP-biotin nick end-labeling method (TUNEL) were examined in a rat model of permanent middle cerebral artery (MCA) occlusion. Cytochrome c was strongly induced in neurons of the ischemic penumbra from 3 h after MCA occlusion, and caspase-3 began to be induced in the same area from 3 h with a peak at 8 h. Neuronal cells in MCA area became TUNEL positive at delayed time, reaching a peak at 24 h. Thus, the peak of induction of cytochrome c preceded that of caspase-3, and these two peaks were also precedence of the peak of DNA-fragmentation. Western blot analysis showed cytosolic expression of cytochrome c from mitochondria. This study demonstrated 1. Rapid release of cytochrome c from mitochondria to the cytosol, mainly in neurons of the cortex at 3 h after ischemia. 2. Subsequent peaks of caspase-3 and TUNEL in this order. These temporal profiles suggest a serial cascadic activation of apoptotic pathways in neuronal death after permanent MCA occlusion of rats.

Animals↗

PubMed2000

Expression, purification and crystallization of human tau-protein kinase I/glycogen synthase kinase-3beta.

Human tau-protein kinase I (TPK-I; also known as glycogen synthase kinase-3beta, GSK-3beta) is a serine/threonine protein kinase. Full-length TPK-I/GSK-3beta was expressed in Escherichia coli as a fusion protein with a 6xHis tag at the C-terminus and was crystallized using the hanging-drop vapour-diffusion method. Prismatic crystals of dimensions 0.4 x 0.2 x 0.1 mm were obtained using 12-15%(w/v) polyethylene glycol 6000 as a precipitant at 278 K. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 82.9, b = 86.1, c = 178.1 A measured at 100 K, diffract to 2.3 A resolution and seem to contain two enzyme molecules per asymmetric unit.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1999

Reduction of tyrosine kinase B and tyrosine kinase C inductions by treatment with neurotrophin-3 after transient middle cerebral artery occlusion in rat.

Infarct volume and immunoreactivities for trkB and trkC in rat brain were compared at 24 h after 90 min of transient middle cerebral artery occlusion (MCAO) between animal groups with or without neurotrophin-3 (NT-3, 10 microg/250 g animal). Treatment of rat brain with topical application of NT-3 significantly reduced infarct volume (P = 0.02) and trkB and trkC inductions. These data suggest that NT-3 reduced the ischemic injury along with the reduction of trkB and trkC inductions.

Administration, Topical↗