Search PubMed⌕ Search

Biomedical subjects

Satoshi Fujita

Publications and source records attributed to Satoshi Fujita.

32 records · Page 2Linked to original sources
PubMed2004

Decreased postsynaptic dopaminergic and cholinergic functions in the ventrolateral striatum of spontaneously hypertensive rat.

Dopamine and acetylcholine receptor functions in spontaneously hypertensive rats (SHR) and in control progenitor Wistar-Kyoto (WKY) rats were assessed, using dopamine D1-like/D2-like receptor-mediated and acetylcholine receptor-mediated jaw movements as readout parameters. Spontaneous behaviours such as locomotor activity, vacuous chewing, grooming, sniffing and rearing occurred significantly more in SHR than in WKY rats. In the anaesthetised rats, a mixture of SKF 38393 (5 micrograms), a dopamine D1-like receptor agonist, and quinpirole (10 micrograms), a dopamine D2-like receptor agonist, readily produced repetitive jaw movements in WKY rats, but not SHR, when bilaterally injected into the ventrolateral striatum; such injections into the nucleus accumbens shell were ineffective in each strain. Bilateral injections of carbachol (2.5 micrograms each side), an acetylcholine receptor agonist, into the ventrolateral striatum elicited repetitive jaw movements in both SHR and WKY rats, but to a far less degree in SHR. The present study demonstrates that spontaneous behaviours are enhanced in SHR, and that postsynaptic dopamine D1-like/D2-like receptors and acetylcholine receptors in the ventrolateral striatum of SHR are hyposensitive when compared to those of WKY rats.

Animals↗
PubMed2004

Biomechanics in uniaxial compression of three distal radius volar plates.

PURPOSE: A new fixed-angle volar plate for a dorsally displaced distal radius fracture was designed with the aim of avoiding soft tissue problems due to dorsal plating. The purpose of this study was to compare the biomechanical properties of this new plate with 2 existing volar plates in a cadaver model. METHODS: Three different plates were applied on surgically simulated unstable extra-articular distal radius fractures in formalin-fixed cadaver radiuses. Group 1 (volarly placed AO titanium Distal Radius plates [Synthes Ltd, Paoli, PA]; n = 6), group 2 (volarly placed titanium Symmetry plates [DePuy ACE Co, El Segundo, CA]; n = 6), and group 3 (volarly placed newly designed titanium plates; n = 6) were tested to failure under axial compression with a materials testing machine. Specimens of all 3 groups had similar bone mineral density. RESULTS: Group 3 specimens had significantly greater elastic limit and ultimate strength than the other 2 groups. Specimens of group 3 had the greatest rigidity, although this was statistically insignificant compared with the other 2 groups. All plates (groups 1, 2, 3) failed in apex volar angulation. CONCLUSIONS: The newly designed plate fixation system is the strongest of the systems tested and may offer adequate stability for the treatment of a distal radius fracture in which the dorsal and/or volar metaphyseal cortex is comminuted severely.

Aged↗
PubMed2004

Muscle tissue changes with aging.

PURPOSE OF REVIEW: This review article focuses on the changes that occur in muscle with age, specifically the involuntary loss of muscle mass, strength and function, termed sarcopenia. Particular emphasis is given to the metabolic alterations that characterize sarcopenia, and to the potentially treatable causes of this condition, including age-related endocrine and nutritional changes, and inactivity. RECENT FINDINGS: Recent data reported include those regarding the potential role of insulin resistance in the development of sarcopenia, the potential role of androgens and growth hormone in the treatment of this condition, the usefulness of exercise including both resistance and aerobic training to improve muscle growth and function, and, finally, the possible use of nutritional manipulations to improve muscle mass. SUMMARY: Sarcopenia is likely a multifactorial condition that impairs physical function and predisposes to disability. It may be prevented or treated with lifestyle interventions and pharmacological treatment. Further long-term investigations are needed, however, to ascertain what type and combinations of interventions are the most efficacious in improving muscle mass and function in older people.

Aged↗
PubMed2004

[Delayed subarachnoid migration of an epidural catheter: a case report].

We often experience migration of an epidural catheter into an undesirable space. Migration of an epidural catheter into the subarachnoid space is a potentially lethal complication. Although almost all migrations of epidural catheters have been reported to occur at insertion of the catheter, we experienced a case of catheter migration into the subarachnoid space two days after its insertion. The symptoms caused by this migration were motor paralysis in the lower extremities and sensory disturbance of the trunk. Neurological and hemodynamic changes in a patient who is undergoing continuous epidural infusion of local anesthetics should be monitored carefully.

Analgesia, Epidural↗
PubMed2003

Prefrontal, accumbal [shell] and ventral striatal mechanisms in jaw movements and non-cyclase-coupled dopamine D1-like receptors.

The effect on jaw movements of intracerebral injections of the dopamine D1-like receptor agents SK&F 83959 (3-methyl-6-chloro-7,8-dihydroxy-1-[3-methylphenyl]-2,3,4,5-tetrahydro-1H-3-benzazepine), SK&F 38393 ([R]-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) and SCH 23390 ([R]-3-methyl-7-chloro-8-hydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) and of injections of the dopamine D2-like receptor agonist quinpirole into the ventrolateral striatum, accumbens shell or prefrontal cortex were studied. SK&F 38393 and SK&F 83959 injected into the ventrolateral striatum synergised with i.v. quinpirole; in the shell of accumbens, SK&F 38393 evidenced weaker synergism with quinpirole, while SK&F 83959 did not synergise with it; neither agent synergised with quinpirole in the prefrontal cortex. Co-injection of SCH 23390 or SK&F 83959 into the prefrontal cortex antagonised jaw movements induced by injection of SK&F 83959 into the ventrolateral striatum in combination with i.v. quinpirole. Injection of SK&F 83959 + quinpirole into the ventrolateral striatum, but not into the accumbens shell, resulted in synergism. These findings indicate a primary, but not exclusive, role for ventral striatal, non-cyclase-coupled dopamine D1-like receptors in the induction of jaw movements. These processes appear to require tonic activity of prefrontal cyclase-linked dopamine D1A [and/or D1B] receptors.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed2003

Archaeal-type rhodopsins in Chlamydomonas: model structure and intracellular localization.

Phototaxis in the unicellular green alga Chlamydomonas reinhardtii is mediated by rhodopsin-type photoreceptor(s). Recent expressed sequence tag database from the Kazusa DNA Research Institute has provided the basis for unequivocal identification of two archaeal-type rhodopsins in it. Here we demonstrate that one is located near the eyespot, wherein the photoreceptor(s) has long been thought to be enriched, along with the results of bioinformatic analyses. Secondary structure prediction showed that the second putative transmembrane helices (helix B) of these rhodopsins are rich in glutamate residues, and homology modeling suggested that some additional intra- or intermolecular interactions are necessary for opsin-like folding of the N-terminal ca. 300-aa membrane spanning domains of 712 and 737-aa polypeptides. These results complement physiological and electrophysiological experiments combined with the manipulation of their expression [O.A. Sineshchekov, K.H. Jung, J.H. Spudich, Proc. Natl. Sci. USA 99 (2002) 8689; G. Nagel, D. Olig, M. Fuhrmann, S. Kateriya, A.M. Musti, E. Bamberg, P. Hegemann, Science 296 (2002) 2395].

Algal Proteins↗
PubMed2003

Landiolol, esmolol and propranolol protect from ischemia/reperfusion injury in isolated guinea pig hearts.

PURPOSE: Beta blockers are thought to exert beneficial effects on the ischemic heart. The authors examined the effects of landiolol (ONO 1101), a highly selective beta1 antagonist, propranolol, a nonspecific beta blocker, and esmolol, a selective beta1 antagonist, on postischemic contractile recovery. Drugs were given prophylactically. METHODS: Ischemia-reperfusion in isolated guinea pig hearts was induced by stopping the perfusion for 45 min and reperfusing for 60 min. Hearts (n = 7 in each group) were treated with or without propranolol (1 or 10 microM), esmolol (5 or 50 microM), or landiolol (20, 100 or 500 microM) ten minutes before inducing ischemia. RESULTS: At the end of reperfusion, left ventricular pressure (LVP) recovered to 64 +/- 3% of the baseline value in the control group. With 1 and 10 microM propranolol, LVP recovered to 90 +/- 5% and 100 +/- 6% of the baseline value at 60 min after reperfusion, respectively. Fifty microM but not 5 microM of esmolol resulted in restoration of LVP to 97 +/- 17% of the pre-ischemic value at 60 min after reperfusion. In hearts pretreated with 100 and 500 microM landiolol, LVP was restored to 109 +/- 5% and 104 +/- 5% of the baseline value, respectively. Landiolol 100 microM did not depress LVP in the pre-ischemic period. CONCLUSIONS: The present study shows that landiolol, an ultra-short-acting cardioselective beta1 blocker, has cardioprotective effects on ischemia-reperfusion injury in isolated guinea pig hearts. All three beta blockers were equally protective but the intermediate dosage of landiolol preserved LVP during the pre-ischemic period.

Adrenergic beta-Antagonists↗
PubMed2003

Modulation of myofilament Ca2+ densitivity by delta- and kappa-opioid agonists in intact guinea pig hearts.

UNLABELLED: We investigated whether delta- and kappa-opioid agonists alter myocardial function, intracellular Ca(2+) concentration ([Ca(2+)](i)), and myofilament Ca(2+) sensitivity in intact guinea pig beating hearts and whether these effects are mediated by an opioid receptor. Intact guinea pig hearts were perfused with modified Krebs Ringer solution containing delta- (TAN-67) and kappa- (ICI-199441) opioid agonists in the absence and presence of delta- (BNTX) and kappa- (nor-BNI) opioid antagonists, respectively, while functional variables and [Ca(2+)](i) were recorded. TAN-67 (1 microM) and ICI-199441 (1 microM) decreased heart rate (P < 0.05). TAN-67 (1 microM) and ICI-199441 (1 micro M) decreased available [Ca(2+)](i) without changing developed left ventricular pressure (LVP) (P < 0.05). TAN-67 (1 microM) and ICI-199441 (1 microM) also caused a leftward shift in the curve of developed LVP as a function of available [Ca(2+)](i) (P < 0.05). ICI-199441 (1 microM) produced a steeper slope in the relation curve compared with baseline (P < 0.05). BNTX (1 microM) and nor-BNI (1 microM) blocked the effects of TAN-67 and ICI-199441, respectively. delta- and kappa-opioid agonists enhance myofilament Ca(2+) sensitivity despite decreasing available [Ca(2+)](i) in intact isolated guinea pig hearts, and these effects are mediated by delta- and kappa-opioid receptor stimulation. IMPLICATIONS: Our results indicate that delta- and kappa-opioid agonists enhance myofilament Ca(2+) sensitivity despite decreasing available intracellular Ca(2+) concentrations in intact isolated guinea pig beating hearts, and these effects are mediated by delta- and kappa-opioid receptor stimulation.

Actin Cytoskeleton↗
PubMed2003

Altered pre- and postsynaptic dopamine receptor functions in spontaneously hypertensive rat: an animal model of attention-deficit hyperactivity disorder.

Dopamine receptor function in spontaneously hypertensive rats (SHR) and in control progenitor Wistar-Kyoto (WKY) rats was assessed from their dopamine D1-like/D2-like receptor-mediated jaw movements and dopamine release from the nucleus accumbens and from the ventrolateral striatum measured by an in vivo microdialysis technique. Spontaneous locomotor activity and rearing were significantly higher in SHR than in WKY rats. Co-administration of SKF 38393 (1.0, 2.0 and 3.0 mg/kg), a dopamine D1-like receptor agonist, and quinpirole (1.0 mg/kg), a dopamine D2-like receptor agonist, produced repetitive jaw movements in WKY rats in a dose-dependent manner. However, this synergism was not evident in SHR. Basal dopamine levels in both the nucleus accumbens and the ventrolateral striatum were lower in SHR than WKY rats, though the levels of dopamine were lower in the nucleus accumbens than the ventrolateral striatum in both strains. After infusion of quinpirole (100 microM for 180 min) the dopamine levels in both regions were reduced. In the nucleus accumbens, the quinpirole-mediated reduction of dopamine release at 40 min and 60 min after infusion was larger in SHR than WKY rats, whereas this difference between the SHR and WKY rats was small in the ventrolateral striatum. The present study therefore suggests that, when compared to WKY rats, postsynaptic dopamine D1-like/D2-like receptors in the SHR are hyposensitive, while presynaptic dopamine D2-like receptors located particularly in the nucleus accumbens are hypersensitive.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed2002

Dopaminergic and cholinergic stimulation of the ventrolateral striatum elicit rat jaw movements that are funnelled via distinct efferents.

It has been reported that two distinct types of jaw movements can be elicited by bilateral injections of drugs into the ventrolateral striatum: (1) dopamine receptor-mediated jaw movements that are elicited by a mixture of (+/-)-6-chloro-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol (SKF 82958; 5 microg) and quinpirole (10 microg), and (2) acetylcholine receptor-mediated jaw movements that are elicited by carbachol (2.5 microg). In the present study, electromyographic analysis was used to characterise these movements: the dopamine receptor-mediated jaw movements were marked by a dominant digastric activity during jaw opening and a dominant masseter activity during jaw closing (digastric/masseter type), whereas the acetylcholine receptor-mediated jaw movements were marked by a dominant digastric activity during jaw opening without any significant change in masseter activity during jaw closing (digastric type). The main goal was to (in)validate the hypothesis that these two types of jaw movements are funnelled via distinct gamma-aminobutyric acid (GABA)ergic output channels. Bilateral injections of both muscimol (25 and 50 ng/0.2 microl per side) and bicuculline (50 and 150 ng/0.2 microl per side) into the ventral pallidum, entopeduncular nucleus or dorsolateral part of the substantia nigra pars reticulata essentially inhibited dopamine receptor-mediated jaw movements to various degrees. In contrast, acetylcholine receptor-mediated jaw movements were inhibited by muscimol given into the entopeduncular nucleus and dorsolateral part of the substantia nigra pars reticulata, whereas these movements were enhanced by bicuculline. The acetylcholine receptor-mediated jaw movements were not affected by muscimol injections into the ventral pallidum, but were inhibited by bicuculline injections. Studies on such injections into the ventral pallidum, entopeduncular nucleus or dorsolateral part of the substantia nigra pars reticulata of naive rats revealed that jaw movements of the digastric/masseter type were elicited either by muscimol injections into the dorsolateral part of the substantia nigra pars reticulata or by combined injections of muscimol and bicuculline into the entopeduncular nucleus, and that jaw movements of the digastric type were elicited only by combined injections of muscimol and bicuculline into the entopeduncular nucleus. Together, the data allow the conclusion that dopamine receptor-mediated and acetylcholine receptor-mediated jaw movements are two distinct types of jaw movements that are funnelled via separate GABAergic output channels. It is suggested that the three different profiles of responses to GABAergic drugs in animals showing either dopamine receptor-mediated or acetylcholine receptor-mediated jaw movements reflect the involvement of three distinct types of output neurons of the striatum, namely: type I neurons with collateralised axons to the ventral pallidum, entopeduncular nucleus and dorsolateral part of the substantia nigra pars reticulata, mediating the dopamine receptor-mediated jaw movements; type II neurons with collateralised axons to the globus pallidus that, in turn, project to the entopeduncular nucleus and the dorsolateral part of the substantia nigra pars reticulata, mediating directly the acetylcholine receptor-mediated jaw movements; and type III neurons with a single axon to the ventral pallidum, mediating indirectly the acetylcholine receptor-mediated movements. It is evident that future studies are required to provide direct evidence in favour of the latter hypothesis.

Animals↗
PubMed2002

Novel approach for linking genotype to phenotype in vitro by exploiting an extremely strong interaction between RNA and protein.

We recently isolated an aptamer that binds to the Tat protein of HIV-1 with extremely high affinity and specificity (Yamamoto, R.; et al. Genes Cells 2000, 5, 371.). In the present study, we exploited this strong binding to develop a novel coupling method that links genotype with phenotype. To strengthen the original RNA-protein interaction still further, we connected three units of the aptamer in tandem and three units of a peptide derived from Tat that interacted with the aptamer. The binding of the resultant RNA, which consisted of three units of the aptamer, to the resultant peptide, which consisted of three units of the peptide, was extremely strong. In fact, the RNA-protein interaction was one of the strongest ever reported, with an apparent K(d) below 16 pM. This strong interaction was attempted for the selection of functional proteins, namely, dihydrofolate reductase (DHFR) or streptavidin, which we chose as an example, and we succeeded in the expected selection, although to a limited extent, of the target protein. The noncovalent but strong interaction described above should be useful as a novel tool for the future selection of functional proteins from pools of random sequences of amino acids.

Codon, Terminator↗
PubMed2002

A novel strategy by the action of ricin that connects phenotype and genotype without loss of the diversity of libraries.

We present a novel strategy for connection of phenotype and genotype in vitro that can be used for the selection of functional proteins even at room temperature. The strategy involves generation of a stable complex between a ribosome, an mRNA, and its translated protein, without removal of the termination codon, as a result of the action of the ricin A chain during translation. We demonstrate the potential selection capacity of this novel strategy by isolating such complexes that contain newly synthesized streptavidin and glutathione-S-transferase (GST) using appropriate ligands. The technique requires no transfection, no chemical synthesis, no ligation, and no removal of the termination codon. Thus our novel "Ribosome-Inactivation Display System (RIDS)" should provide, without loss of the pool population, a reliable, simple, and robust selection system for in vitro evolution of the properties of proteins in a predictable direction by a combination of randomization and appropriate selection strategies.

Gene Expression Profiling↗
PubMedDate not supplied

Flexor tendon repair in zone II with 6-strand techniques and early active mobilization.

PURPOSE: There are many biomechanic studies of 6-strand suture techniques for active mobilization, but few reports have described the clinical outcome in zone II flexor tendon lacerations. We discuss the clinical results of zone II flexor tendon repair using 2 of these techniques followed by controlled early active mobilization. METHODS: Six-strand sutures using the number 1 technique by Yoshizu or a triple-looped suture technique were used to repair flexor tendons in 27 fingers from 21 consecutive patients. Fingers were mobilized by combining active extension and passive or active flexion in a protective splint for the first 3 weeks after surgery. The follow-up period averaged 13 months. RESULTS: Based on the original Strickland criteria, the results were excellent in 17 fingers, good in 9, and fair in 1. The average flexion was 62 degrees for distal interphalangeal joints and 91 degrees for proximal interphalangeal joints. None of the repaired tendons ruptured. CONCLUSIONS: The 6-strand flexor tendon suture technique followed by controlled active mobilization protected with a dorsal splint is safe, produces no ruptures, and achieves very good results in zone II flexor tendon laceration repair. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level II.

Adolescent↗