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Biomedical subjects

F Saito

Publications and source records attributed to F Saito.

At least 19 recordsLinked to original sources
PubMed2001

Effects of quartz addition on the mechanochemical dechlorination of chlorobiphenyl by using CaO.

Grinding a mixture of 3-chlorobiphenyl (BP-Cl) and CaO with or without the addition of quartz was conducted in air by a planetary ball mill to investigate the mechanochemical dechlorination of BP-Cl. The dechlorinating reaction proceeds with an increase in grinding time, and over 99% of BP-Cl is decomposed at 360 min. Washing the ground sample with different solvents results in different products. Addition of quartz to the grinding mixture facilitates dechlorination efficiency, especially in the case of a high weight ratio of BP-Cl to CaO.

Biomechanical Phenomena↗
PubMed2001

A stoichiometric complex of neurexins and dystroglycan in brain.

In nonneuronal cells, the cell surface protein dystroglycan links the intracellular cytoskeleton (via dystrophin or utrophin) to the extracellular matrix (via laminin, agrin, or perlecan). Impairment of this linkage is instrumental in the pathogenesis of muscular dystrophies. In brain, dystroglycan and dystrophin are expressed on neurons and astrocytes, and some muscular dystrophies cause cognitive dysfunction; however, no extracellular binding partner for neuronal dystroglycan is known. Regular components of the extracellular matrix, such as laminin, agrin, and perlecan, are not abundant in brain except in the perivascular space that is contacted by astrocytes but not by neurons, suggesting that other ligands for neuronal dystroglycan must exist. We have now identified alpha- and beta-neurexins, polymorphic neuron-specific cell surface proteins, as neuronal dystroglycan receptors. The extracellular sequences of alpha- and beta-neurexins are largely composed of laminin-neurexin-sex hormone-binding globulin (LNS)/laminin G domains, which are also found in laminin, agrin, and perlecan, that are dystroglycan ligands. Dystroglycan binds specifically to a subset of the LNS domains of neurexins in a tight interaction that requires glycosylation of dystroglycan and is regulated by alternative splicing of neurexins. Neurexins are receptors for the excitatory neurotoxin alpha-latrotoxin; this toxin competes with dystroglycan for binding, suggesting overlapping binding sites on neurexins for dystroglycan and alpha-latrotoxin. Our data indicate that dystroglycan is a physiological ligand for neurexins and that neurexins' tightly regulated interaction could mediate cell adhesion between brain cells.

Alternative Splicing↗
PubMed2001

Processing of beta-dystroglycan by matrix metalloproteinase disrupts the link between the extracellular matrix and cell membrane via the dystroglycan complex.

The dystroglycan complex is a membrane-spanning complex composed of two subunits, alpha- and beta-dystroglycan. alpha-dystroglycan is a cell surface peripheral membrane protein which binds to the extracellular matrix (ECM), whereas beta-dystroglycan is an integral membrane protein which anchors alpha-dystroglycan to the cell membrane. The dystroglycan complex provides a tight link between the ECM and cell membrane. Dysfunction of the dystroglycan complex has commonly been implicated in the molecular pathogenesis of severe forms of hereditary neuromuscular diseases, including Duchenne muscular dystrophy, Fukuyama-type congenital muscular dystrophy and sarcoglycanopathy (LGMD2C, -D, -E and -F). To begin to clarify the pathway by which the dysfunction of the dystroglycan complex could lead to muscle cell degeneration, we investigated the proteolytic processing of the dystroglycan complex in this study. We demonstrate that (i) a 30 kDa fragment of beta-dystroglycan is expressed in peripheral nerve, kidney, lung and smooth muscle, but not skeletal muscle, cardiac muscle or brain, and (ii) this fragment is the product of proteolytic processing of the extracellular domain of beta-dystroglycan by the membrane-associated matrix metalloproteinase (MMP) activity. Importantly, furthermore, we demonstrate that this processing disintegrates the dystroglycan complex. Our results indicate that the processing of beta-dystroglycan by MMP causes the disruption of the link between the ECM and cell membrane via the dystroglycan complex, which could have profound effects on cell viability. Based on these and previously reported findings, we propose a hypothesis that this processing may play a crucial role in the molecular pathogenesis of sarcoglycanopathy.

Animals↗
PubMed2001

Non-Hodgkin's lymphoma of the ascending colon in a patient with becker muscular dystrophy: report of a case.

We herein present the findings of a 10-year-old boy with non-Hodgkin's lymphoma of the ascending colon which caused intussusception and intestinal bleeding. He had a history of Becker muscular dystrophy. However, he had neither hypertrophic calves nor cardiomyopathy, and his serum creatine kinase (CK) level always exceeded 2000 IU/l. Preoperatively, a laboratory examination revealed high serum levels of CK (2038IU/l), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH), and the blood hemoglobin level was 7.0g/dl. A barium enema examination revealed an intussusception in his ascending colon, which was found to be a highly vascular tumor on Doppler ultrasound scans. A right hemicolectomy was performed. Macroscopically, the 5 x 6 x 8-cm solid tumor of the ascending colon resembled a submucosal tumor and had two ulcerous lesions at the tip. The tumor was histologically diagnosed to be a diffuse large B-cell lymphoma of the ascending colon. General examinations revealed no involvement of lymphoma postoperatively. At 13 months after surgery, the CK (37861U/l), AST (110lU/l), ALT (1381U/ l), and LDH (420lU/l) levels are still high, and the patient is doing well without any signs of recurrence.

Child↗
PubMed2001

Differential expression of two BMP antagonists, gremlin and Follistatin, during development of the chick feather bud.

Expression of four BMP antagonist genes, noggin, chordin, gremlin and Follistatin, was examined during chick feather development. Although expression of noggin and chordin was not detected, gremlin and Follistatin were expressed differentially in feather buds. The differential expression patterns of gremlin and Follistatin change dynamically from the nascent inter-feather bud region to the posterior domain of the feather bud.

Animals↗
PubMed2001

Recovery of 18F from [18O] water by electrochemical method.

An electrochemical method for producing 18F sources for the slow positron beam was applied to the recovery of 18F from H2(18)O water. The 18F of activities 150-227 mCi (5.55-8.40 GBq) was electro-deposited on a graphite rod and then emitted into pure water. The best result of the efficiency for the electro-deposition for 5 min was 97% and that for the electro-emission for 5 min was 89%. The H2(18)O water is expected to be reused much more easily by this method than by the ion exchange resin method. The metal impurities contained in the 18F solution were considerably reduced by using this method.

Journal Article↗
PubMed2001

Sonochemical synthesis of hydroxyapatite from H3PO4 solution with Ca(OH)2.

Ultrasound was irradiated to an aqueous suspension containing phosphoric acid (H3PO4) and calcium hydroxide (Ca(OH)2) to investigate the sonochemical effect on preparation of hydroxyapatite (Ca10(PO4)6(OH)2, HAp). HAp monophase could be synthesized from the suspension sonicated for 60 min. The reaction for HAp was promoted more effectively than that of the heating method conducted at the same conditions as those for the sonicating method. The equilibrium pH of the suspensions sonicated over 60 min was maintained neutral, suggesting that the synthesis reaction was almost completed. The ultrasonic irradiation played an important role to progress the heterogeneous reaction and the preparation of very fine HAp powder.

Biocompatible Materials↗
PubMed2001

The association between obstetric complications and childhood-onset schizophrenia: a replication study.

BACKGROUND: Many previous studies have shown that individuals who develop schizophrenia in adult life are more likely than normal controls to have a history of obstetric complications (OCs) at birth. However, little attention has been paid to the involvement of OCs in the risk of developing childhood-onset schizophrenia (COS). In our earlier report, we found an association between OCs and the development of COS. In this study, we determined whether the association could be replicated in another, independent set of patients with COS. METHODS: OCs, birth weight and gestational age were retrospectively assessed in 35 children, aged between 14 and 15 years old (average 15.4 years), who met the DSM-III-R criteria for schizophrenia, and in age- and gender-matched controls (children with anxiety disorders). RESULTS: The COS patients showed significantly greater scores in all of the three measures of OCs according to the Parnas et al. scale compared to controls. Moreover, individuals exposed to OCs were about 3.2 times (odds ratio = 3.22; 95% confidence interval, 1.1-9.8) more likely to develop schizophrenia than those without a history of OCs. The mean birth weight was significantly lower in schizophrenics than in controls (P < 005). The frequency of prematurity signs with weight < 2500 g was significantly higher in schizophrenics than in controls (P < 0.05). CONCLUSION: Repeatedly reported association between OCs and adult-onset schizophrenia have also been demonstrated in patients with COS. This suggests that there may be a continuity between childhood- and adult-onset schizophrenia.

Adolescent↗
PubMed2001

Differences of symptoms and standardized weight index between patients with early-onset and late-onset anorexia nervosa.

OBJECTIVE: There have so far been no studies that directly compared clinical features between patients with early- and late-onset anorexia nervosa (AN). METHOD: We identified 64 patients with DSM-III-R AN. We defined individuals as an early-onset group, who had an age of onset before 14 years (N = 31), and the remaining as a late-onset group (N = 33). The clinical symptoms, body weight and weight index, were compared between the two groups. Subjects were dichotomized into those with extremely low weight and those remaining. We compared the proportion of the patients with extremely low weight between the two groups. RESULTS: The rates of 'self-induced vomiting' and 'purging' were significantly lower in a group of patients with early-onset AN than in those with late-onset AN. There were significantly fewer subjects with extremely low weight in early-onset than in late-onset AN group. CONCLUSION: We found clear differences in clinical features between early- and late-onset AN groups.

Adolescent↗
PubMed2001

A case of late onset cardiac amyloidosis with a new transthyretin variant (lysine 92).

A new transthyretin (TTR) variant (lysine 92), which causes late onset cardiac amyloidosis, is described in a 71-year-old man. The patient at first had syncope due to ventricular tachycardia and was admitted our hospital. Typical findings of cardiac amyloidosis were observed by echocardiography, and a diagnosis of systemic amyloidosis was made by rectal biopsy. The man died approximately 3 years and 6 months after first admission, with gradually worsening congestive heart failure. Pathological examination showed prominent amyloid deposits in the heart and the vascular wall of many organs including the liver, pancreas, kidney, lung, and gastrointestinal tracts. Amyloid protein of transthyretin type was indicated by immunohistochemical study, and DNA sequencing identified a novel mutation in the transthyretin gene encoding 92 glutamine --> lysine. A polymerase chain reaction-induced mutation restriction analysis with a mismatched antisense primer showed that the patient was heterozygous for the TTR Lys92 allele.

Adult↗
PubMed2001

Serine acetyltransferase involved in cysteine biosynthesis from spinach: molecular cloning, characterization and expression analysis of cDNA encoding a plastidic isoform.

A cDNA clone that encodes a chloroplast-localizing isoform of serine acetyltransferase (SATase) (EC 2.3.1.30) was isolated from spinach (Spinacia oleracea L.). The cDNA encodes a polypeptide of 347 amino acids containing a putative transit peptide of ca. 60-70 amino acids at the N-terminal. Deduced amino acid sequence of SATase from spinach exhibited homology with other SATases from plants. DNA blot hybridization analysis showed the presence of 2-3 copies of Sat gene in the genome of spinach. RNA blot hybridization analysis indicated the constitutive expression of Sat gene in green and etiolated seedlings of spinach. Bacterial expression of the cDNA could directly rescue the cysteine auxotrophy of Escherchia coli caused by a lack of SATase locus (cysE). Catalytically active SATase protein was produced in E. coli cells. L-Cysteine, an end product of the cysteine biosynthetic pathway, inhibited the activity of recombinant spinach SATase, indicating the regulatory function of SATase in this metabolic pathway. A chloroplastic localization of this spinach SATase was revealed by the analyses of transgenic plant expressing transit peptide of SATase-beta-glucuronidase (GUS) fusion protein, and transient expression using the transit peptide-green fluorescent protein (GFP) fusion protein. The result from in vitro translation analysis suggests that this cDNA may encode both plastidic and cytosolic SATases.

Acetyltransferases↗
PubMed2001

Evaluation of loudness-level weightings for assessing the annoyance of environmental noise.

Assessment of the annoyance of combined noise environments has been the subject of much research and debate. Currently, most countries use some form of the A-weighted equivalent level (ALEQ) to assess the annoyance of most noises. It provides a constant filter that is independent of sound level. Schomer [Acust. Acta Acust. 86(1), 49-61 (2000)] suggested the use of the equal loudness-level contours (ISO 226, 1987) as a dynamic filter that changes with both sound level and frequency. He showed that loudness-level-weighted sound-exposure level (LLSEL) and loudness-level-weighted equivalent level (LL-LEQ) can be used to assess the annoyance of environmental noise. Compared with A-weighting, loudness-level weighting better orders and assesses transportation noise sources, sounds with strong low-frequency content and, with the addition of a 12-dB adjustment, it better orders and assesses highly impulsive sounds vis-a-vis transportation sounds. This paper compares the LLSEL method with two methods based on loudness calculations using ISO 532b (1975). It shows that in terms of correlation with subjective judgments of annoyance-not loudness-the LLSEL formulation performs much better than do the loudness calculations. This result is true across a range of sources that includes aircraft, helicopters, motor vehicles, trains, and impulsive sources. It also is true within several of the sources separately.

Humans↗
PubMed2001

Inhibition by carbapenem antibiotic imipenem of intestinal absorption of valproic acid in rats.

The concomitant use of carbapenem antibiotics with valproic acid has been prohibited because panipenem induced a decrease in plasma concentration of valproic acid in epileptic patients during valproic acid therapy. To clarify the possible mechanism of the carbapenem-valproic acid interaction, we investigated the effect of imipenem on the pharmacokinetic behaviour of valproic acid in rats. Co-administration of imipenem (30 mg kg(-1), i.v.) induced a decrease in the peak plasma concentration of valproic acid after oral administration. However, the imipenem-induced decrease in plasma concentrations of valproic acid was not observed within 60 min after intravenous injection of valproic acid. By utilizing in-situ vascular and luminal perfused small intestine, it was confirmed that absorption of valproic acid from the luminal to the vascular perfusate was decreased in the presence of imipenem (0.5 mM) in the vascular perfusate. The everted gut sac method was used to determine the effect of imipenem on active transport of valproic acid. The accumulation of valproic acid on the serosal side of the intestinal sac against the concentration gradient was reduced by lactic acid that inhibits the carrier-mediated transport of valproic acid across the intestinal brush-border membrane. However, imipenem did not affect the active transport of valproic acid. Therefore, the inhibition by imipenem of valproic acid absorption may be caused by a mechanism different from that of lactic acid. In conclusion, imipenem inhibits the intestinal absorption of valproic acid, which contributes to the decrease in plasma concentration of valproic acid after oral administration.

Administration, Oral↗
PubMed2000

Expression of dystroglycan and laminin-2 in peripheral nerve under axonal degeneration and regeneration.

In Schwann cells, the transmembrane glycoprotein beta-dystroglycan composes the dystroglycan complex, together with the extracellular glycoprotein alpha-dystroglycan which binds laminin-2, a major component of the Schwann cell basal lamina. To provide clues to the biological functions of the interaction of the dystroglycan complex with laminin-2 in peripheral nerve, the expression of beta-dystroglycan and laminin-alpha2 chain was studied in rat sciatic nerves undergoing axonal degeneration and regeneration as well as in normal condition. In normal sciatic nerve, immunoreactivity for the cytoplasmic domain of beta-dystroglycan was consistently and selectively localized in the Schwann cell cytoplasm underlying the outer (abaxonal) membrane apposing the basal lamina. While beta-dystroglycan expression was gradually down-regulated in Schwann cells losing contact with axons during axonal degeneration, it was progressively up-regulated as the regenerating process of ensheathment and myelination proceeded during regeneration. Interestingly, beta-dystroglycan expression, when detectable, was always restricted to the Schwann cell cytoplasm beneath the outer membrane apposing the basal lamina during both axonal degeneration and regeneration. Furthermore, laminin-alpha2 immunoreactivity roughly paralleled that of beta-dystroglycan during both axonal degeneration and regeneration, indicating that the expression of beta-dystroglycan and laminin-alpha2 is induced and maintained by the Schwann cell contact with axons. Our results indicate that the dystroglycan complex is involved in the adhesion of the Schwann cell outer membrane with the basal lamina and suggest that the dystroglycan complex may play a role in the process of Schwann cell ensheathment and myelination through the interaction with laminin-2.

Animals↗
PubMed2000

Prepulse effects on the interaction of intense femtosecond laser pulses with high-Z solids

Kalpha emission of high-Z solid targets irradiated by an intense, short (<100 fs) laser pulse in the 10 keV region is shown to be sensitive to the electron energy cutoff, which is strongly dependent on the density gradient of the plasma corona formed by a long prepulse. The absorption rate of short laser pulses, the hot electron distribution, and x-ray emission from a Cu slab target are studied via a hybrid model, which combines the hydrodynamics, collisional particle-in-cell, and Monte Carlo simulation techniques, and via a direct spectroscopic measurement. An absorption mechanism originating from the interaction of the laser pulse with plasma waves is found to increase the absorption rate by over 30% even for a very short, s-polarized laser pulse. Calculated and measured x-ray spectra are in good agreement, confirming the electron energy cutoff.

Journal Article↗
PubMed2000

[A case of callosal apraxia without agraphia and acquired stuttering associated with callosal infarction].

We report a 52-year-old right-handed man with cerebral infarction of the right anterior cerebral artery area. The MRI findings showed cerebral infarction in the trunk of the right corpus callosum, although some part of the posterior half of the trunk was spared. Some part of right precuneal gyrus, cingulate gyrus were also involved. The clinical feature of this case is characterized by following two points. First, although callosal apraxia is usually accompanied by agraphia, he showed apraxia with the left hand, but showed no agraphia. Secondary, he showed speech dysfluency mainly characterized by initial syllable repetitions. The nature of this speech dysfluency was determined as acquired stuttering. This case suggests that the pathway for praxis locates distinct portion from that for writing on corpus callosum. We analyzed callosal lesions of previous studies reporting callosal apraxia without agraphia, then compared to that of this case. And we also reviewed acquired stuttering report caused by callosal lesions. Consequently, we suggest that apraxia and stuttering were caused by damage of the trunk of the corpus callosum. While writing was preserved by the intact fibers in the posterior half of the trunk.

Apraxias↗