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Biomedical subjects

N Saitoh

Publications and source records attributed to N Saitoh.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Recent advances in echocardiographic diagnosis of ischemic heart disease].

Before the early 1990s, the diagnostic usefulness of echocardiography for ischemic heart disease had been relatively limited compared with that for other cardiac diseases such as valvular disease, congenital anomalies and cardiomyopathies. The principal role of echocardiography was to assess persistent regional wall motion abnormality as well as to detect complications of myocardial infarction. However, recent technological advances have created many newer applications of echocardiography in this field. One of the most important advances was seen in the field of stress echocardiography. Dobutamine stress echocardiography has become an established method of diagnosing transient myocardial ischemia due to coronary stenosis and assessing the myocardial viability of a persistently akinetic segment. More recently, several new contrast agents have been developed or will be available in the near future to visualize the blood stream within the left heart cavity and myocardial blood flow. Simultaneously, new ultrasound technologies including harmonic imaging and gated intermittent imaging have enhanced the selective visualization of contrast agents and will contribute to noninvasive imaging of coronary microcirculation. Harmonic imaging has also been shown to improve quality of B-mode image without a contrast agent and will play an important role in the clinical recognition of wall motion abnormality in patients with ischemic heart disease. Recent advances in three-dimensional technology have enabled accurate measurements of left ventricular volume and ejection fraction without any geometrical assumption, which may be especially important for the evaluation of ischemic patients who often have a deformed left ventricular cavity due to remodeling.

Echocardiography↗
PubMed1999

Overexpression of myotonic dystrophy protein kinase in C2C12 myogenic culture involved in the expression of ferritin heavy chain and interleukin-1alpha mRNAs.

The specific function of myotonic dystrophy protein kinase (DMPK) is still not known. We found that overexpression of human DMPK in C2C12 myogenic culture induces the expression of ferritin heavy chain (FN-H) mRNA using differential display analysis. The quantity of FN-H mRNA was greater in the DMPK transfectant with five CTG triplet repeats in the 3'-untranslated region, while it was lower in the transfectant with 46 CTG repeats, over that of the control clone. We also investigated the quantity of interleukin 1-alpha (IL-1alpha) mRNA in each culture, due to the fact that this cytokine is able to induce FN-H expression, regardless of the concentration of free iron. Quantitative, competitive polymerase chain reaction (PCR) analysis revealed that the quantity of IL1-alpha mRNA is higher in the transfectant with five repeats, compared to the quantity of mRNA in the control clone; however, it is markedly lower in the clone with 46 repeats. These results suggest that overexpression of DMPK in C2C12 cultures may up-regulate IL-1alpha expression, resulting in the induction of FN-H expression. However, a large number of CTG repeats in the 3'-untranslated region of the DMPK gene may affect the pathway of IL-1alpha transcription, thereby resulting in decreased expression of FN-H.

Animals↗
PubMed1999

DNA replication errors produced by the replicative apparatus of Escherichia coli.

It has been hard to detect forward mutations generated during DNA synthesis in vitro by replicative DNA polymerases, because of their extremely high fidelity and a high background level of pre-existing mutations in the single-stranded template DNA used. Using the oriC plasmid DNA replication in vitro system and the rpsL forward mutation assay, we examined the fidelity of DNA replication catalyzed by the replicative apparatus of Escherichia coli. Upon DNA synthesis by the fully reconstituted system, the frequency of rpsL-mutations in the product DNA was increased to 1.9x10(-4), 50-fold higher than the background level of the template DNA. Among the mutations generated in vitro, single-base frameshifts predominated and occurred with a pattern similar to those induced in mismatch-repair deficient E. coli cells, indicating that the major replication error was slippage at runs of the same nucleotide. Large deletions and other structural alterations of DNA appeared to be induced also during the action of the replicative apparatus.

Base Pairing↗
PubMed1999

Conservation of sequence and structure flanking the mouse and human beta-globin loci: the beta-globin genes are embedded within an array of odorant receptor genes.

In mouse and human, the beta-globin genes reside in a linear array that is associated with a positive regulatory element located 5' to the genes known as the locus control region (LCR). The sequences of the mouse and human beta-globin LCRs are homologous, indicating conservation of an essential function in beta-globin gene regulation. We have sequenced regions flanking the beta-globin locus in both mouse and human and found that homology associated with the LCR is more extensive than previously known, making up a conserved block of approximately 40 kb. In addition, we have identified DNaseI-hypersensitive sites within the newly sequenced regions in both mouse and human, and these structural features also are conserved. Finally, we have found that both mouse and human beta-globin loci are embedded within an array of odorant receptor genes that are expressed in olfactory epithelium, and we also identify an olfactory receptor gene located 3' of the beta-globin locus in chicken. The data demonstrate an evolutionarily conserved genomic organization for the beta-globin locus and suggest a possible role for the beta-globin LCR in control of expression of these odorant receptor genes and/or the presence of mechanisms to separate regulatory signals in different tissues.

Animals↗
PubMed1999

Comparison of venoarterial versus venovenous access in the cerebral circulation of newborns undergoing extracorporeal membrane oxygenation.

This study was designed to compare venoarterial (VA) with venovenous (VV) access in the cerebral circulation of newborn infants during extracorporeal membrane oxygenation (ECMO). Among 14 infants with VA ECMO, 7 had no intracranial complications (group 1), while the others (group 2) developed intracranial hemorrhage (ICH). In contrast, among 19 infants with VV ECMO, only 1 developed ICH. Serial echocardiograms were performed before and after 1, 6, 12, and 24 h and 2 and 3 days of ECMO. The mean cerebral blood flow (CBF) velocities were measured in the anterior cerebral artery (ACA), right and left internal carotid arteries (Rt, Lt-ICA), basilar artery (BA), and right and left middle cerebral arteries (Rt, Lt-MCA). Ejection fraction (EF), cardiac output (CO), and stroke volume (SV) were also measured using standard echography. The velocity levels in the ACA, Rt-MCA, and Lt-MCA in VA ECMO were lower than those in VV ECMO, while those in the Lt-ICA and BA in VA ECMO were higher than those in VV ECMO. The EF, CO, and SV were lower in cases of VA ECMO than in VV ECMO. In cases of VA ECMO, there were no differences between groups 1 and 2 in velocities in the ACA, Rt-ICA, or Lt-ICA. However the velocities in group 2 in the BA, Rt-MCA, and Lt-MCA were lower than those in group 1 before and during ECMO. Similarly, the EF, CO, and SV were lower in group 2 (12.0%-31.0%, 0. 10-0.32 l/min, and 0.66-1.55 ml, respectively) than in group 1 (29. 5%-49.3%, 0.25-0.63 l/min, and 2.15-3.85 ml) during ECMO. However, in the infants on VV ECMO the CBF was either maintained or gradually increased before and during ECMO. Their cardiac parameters were: EF 46.1%-53.0%, CO 0.43-0.52 l/min, and SV 2.72-3.84 ml during ECMO. It is concluded that in VA ECMO CBF velocities, particularly in infants who developed ICH, decreased after the onset of ECMO in association with poor cardiac function, while in VV ECMO they were stable, probably due to normal systemic hemodynamics and cardiac function.

Arteriovenous Shunt, Surgical↗
PubMed1999

Hematospermia: an investigation of the bleeding site and underlying lesions.

BACKGROUND: The site of hemorrhage and causative lesions in patients with hematospermia were evaluated using the puncture technique for seminal vesicles and/or müllerian duct cysts under ultrasound guidance. METHODS: Twenty-one patients aged 26-75 years (mean, 49.8 years) underwent transperineal needle aspiration of the seminal vesicles and/or müllerian duct cysts guided by transrectal ultrasonography (TRUS). RESULTS: Dark reddish seminal vesicle fluid was aspirated and the site of bleeding was considered to be the seminal vesicles in 11 patients (52%) (group A). In group A, abnormalities of the seminal vesicles were noted in nine patients (82%). These consisted of dilated seminal vesicles in seven (bilateral in four, unilateral in three), a seminal vesicle cyst in one and seminal vesicle amyloidosis in one. A müllerian duct cyst was confirmed to be the bleeding site in two patients (10%; group B). The bleeding site was estimated to be organs rather than the seminal vesicles in four patients (group C), in all of whom ectopic prostatic tissue was observed in the prostatic urethra. In groups B and C, seminal vesicle abnormalities were not detected by TRUS. In the remaining four patients (group D), failure to aspirate seminal vesicle fluid means that it is unclear whether hemorrhage was from the seminal vesicle or from another source. In group D, ectopic prostatic tissue was demonstrated in the prostatic urethra of three patients and unilateral seminal vesicle dilation was detected by TRUS in one patient. CONCLUSION: Puncture of the seminal vesicles and/or mullerian duct cysts under ultrasonic guidance as well as cystourethroscopy is a useful and minimally invasive examination for determination of the bleeding site responsible for hematospermia.

Adult↗
PubMed1999

The position and size of radiological nephrogram in Japanese preschool children.

The early detection of retroperitoneal masses in children, such as neuroblastoma, Wilm's tumor, hydronephrosis and cystic renal diseases, has a great clinical importance for the improvement of their prognosis. The kidney is often affected in its size or position by these lesions, and occasionally allows clinicians to find a clue to reach the correct diagnosis before the patient become symptomatic. Since we had no clinically available nomogram on the position and the size of the kidney in Japanese children, we measured the size and position of the kidneys on plain abdominal x-rays in 347 Japanese children in preschool years with a special attention to their relationship with the spine. As a result, the nomogram showed age dependent growth of the kidneys keeping almost the same ratio with the spine, while the distance between the upper pole of the kidney and the spine remained less than 10 mm in all age groups. Our nomogram may be useful not only for picking up the malposition of the kidneys but also for the follow up of the patients with chronic renal diseases affecting the growth of the kidneys.

Aging↗
PubMed1999

[Mitral valve replacement under cardiopulmonary bypass which complicated by multiple sclerosis: a case report].

The 60-year-old women who complicated by multiple sclerosis was referred to our hospital under diagnosis of mitral valve stenosis and tricuspid valve regurgitation. The mitral valve replacement and the tricuspid valve annuloplasty were performed under cardiopulmonary bypass. In the state of multiple sclerosis, even an operation by general anesthesia could become a cause of abrupt change, but by appropriate management during and after surgery, the post operative course was uneventful without any complications, and the patient discharged on the 35th post operative day.

Cardiopulmonary Bypass↗
PubMed1998

Inhibition of skeletal muscle sarcoplasmic reticulum Ca2+-ATPase by nitric oxide.

The effects of nitric oxide on the activities of thapsigargin-sensitive sarcoplasmic reticulum Ca2+-ATPase (SERCA) and Ca2+ uptake by sarcoplasmic reticulum (SR) membranes prepared from white skeletal muscle of rabbit femoral muscle were studied. Pretreatment of the SR preparations with nitric oxide at concentrations of up to 250 microM for 1 min decreased the SERCA activity concentration dependently, and also decreased their Ca2+ uptake. Both these effects of nitric oxide were reversible. Inhibitors of guanylyl cyclase and protein kinase G (PKG) had no significant effect on the nitric oxide-induced inhibitions of SERCA and Ca2+ uptake. Moreover, dithiothreitol did not reverse the inhibitory effects of nitric oxide on SERCA and Ca2+ uptake. These findings suggest that nitric oxide inhibits SERCA, mainly SERCA 1, of rabbit femoral skeletal muscle by an action independent of the cyclic GMP-PKG system or oxidation of thiols, and probably by a direct action on SERCA protein.

Aminoquinolines↗
PubMed1998

Patch clamp studies on ion pumps of the cytoplasmic membrane of Escherichia coli. Formation, preparation, and utilization of giant vacuole-like structures consisting of everted cytoplasmic membrane.

Formation of giant protoplasts from normal Escherichia coli cells resulted in the formation of giant vacuole-type structures (which we designate as provacuoles) in the protoplasts. Electron microscopic observation revealed that these provacuoles were surrounded by a single membrane. We detected inner (cytoplasmic) membrane proteins in the provacuolar membrane but not outer membrane proteins. Biochemical analyses revealed that the provacuoles consist of everted cytoplasmic membranes. We applied the patch clamp method to the giant provacuoles. We have succeeded in measuring current that represents inward movement of H+ because of respiration and to ATP hydrolysis by the FoF1-ATPase. Such current was inhibited by inhibitors of the respiratory chain or FoF1-ATPase. This method is applicable for analyses of ion channels, ion pumps, or ion transporters in E. coli or other microorganisms.

Cytoplasm↗
PubMed1998

[A combination of reoperation for pseudoaneurysm following the Cabrol procedure and total aortic arch replacement in a patient with Marfan syndrome--a case with an aberrant right subclavian artery].

A 44-year-old male with Marfan's syndrome had undergone an initial operation for DeBakey type I acute aortic dissection with annulo-aortic ectasia. He had undergone replacement of the ascending aorta and aortic valve with a composite graft and reconstruction of the coronary artery by the Cabrol procedure. At 5 years after the initial surgery he experienced chest pain and was subsequently examined. Computed tomography revealed a pseudoaneurysm in the ascending aorta and the residual aortic dissection. The maximum diameter of the pseudoaneurysm was 85 mm and the maximum diameter of the aortic arch was 55 mm. The aortic arch was associated with an aberrant right subclavian artery. Angiography revealed that the pseudoaneurysm was caused by leakage at the coronary ostium-graft anastomoses. We repaired the anastomoses and performed total aortic arch replacement with reconstruction of four arch branches. The postoperative course was uneventful without any complications. We report this case because there have been few reports regarding arch replacement in cases with an aberrant right subclavian artery.

Aortic Dissection↗
PubMed1998

Local cytokine expression in steroid-modified tinea faciei.

In tinea faciei, a dermatophyte infection of the face, early stage lesions show erythema with crust and/or vesicles, a condition often misdiagnosed as dermatitis. Steroid application retards the healing in some cases and may induce penetration of the dermatophyte hyphae into hair and hair follicles. In the present study, we examined local immunity mediated by cytokines derived from lesional T lymphocytes in late stage of this disease. Interferon-gamma (IFN-gamma) and macrophage migration inhibitory factor (MIF) were highly expressed, but neither interleukin-4 (IL-4) nor interleukin-5 (IL-5) could be detected by RT-PCR using cryosections. These data suggested that IFN-gamma and MIF may be important in the delayed-type hypersensitivity (DTH) response against the fungus in the hair follicle in late stages.

Adult↗
PubMed1998

Relationship between muscarinic autoinhibition and the inhibitory effect of morphine on acetylcholine release from myenteric plexus of guinea pig ileum.

The relationship between muscarinic autoinhibition and the inhibitory effect of morphine on acetylcholine (ACh) release was investigated in a longitudinal muscle with myenteric plexus (LMMP) preparation of guinea pig ileum. Morphine (10 microM) inhibited spontaneous and evoked ACh release by electrical field stimulation (EFS) at 1 Hz but not at 10 Hz. Atropine (1 microM) did not affect the resting ACh release, but it significantly increased EFS-evoked release, suggesting activation of muscarinic autoreceptors by ACh released during EFS. Only when the autoinhibition was weakened by atropine, morphine exhibited an inhibitory effect on the EFS-evoked release at 10 Hz. Bethanechol (300 microM) inhibited the EFS-evoked release at 1 Hz but not 10 Hz, suggesting that muscarinic autoreceptors are partially or almost fully activated at 1 or 10 Hz stimulation, respectively. After bethanechol treatment, morphine did not exhibit its inhibitory effect on the EFS-evoked release at 1 Hz. Naloxone (1 microM) increased spontaneous and EFS-evoked ACh release at 1 Hz but not at 10 Hz. Following treatment with atropine, naloxone also increased ACh release at 10-Hz stimulation. These results suggest that morphine and an endogenous opioid inhibit ACh release from LMMP preparations when muscarinic autoinhibition mechanism does not fully work. This inhibitory effect of morphine is discussed in relation to the calcium sensitivity of the preparations in ACh release.

Acetylcholine↗
PubMed1998

Relationship between inhibitory effect of endogenous opioid via mu-receptors and muscarinic autoinhibition in acetylcholine release from myenteric plexus of guinea pig ileum.

Relationship between activation of opioid receptors and muscarinic autoinhibition in acetylcholine (ACh) release from the myenteric plexus was studied in longitudinal muscle myenteric plexus (LMMP) preparations of guinea pig ileum. A mu-receptor agonist, [D-Ala2, N-Me-Phe4, Gly5-ol] enkephalin (DAMGO), at a concentration of 1 microM inhibited the ACh release evoked by electrical field stimulation (EFS) at 1 Hz but not at 10 Hz. After the muscarinic autoreceptors were blocked with atropine (1 microM), DAMGO inhibited EFS-evoked ACh release also at 10 Hz. After the autoreceptors were potently activated with muscarine (200 microM), the inhibitory effect of DAMGO at 1 Hz was abolished. A kappa-receptor agonist, U-50,488, at 1 microM inhibited the EFS-evoked ACh release both at 1 and 10 Hz. U-50,488 inhibited ACh release regardless of the presence of atropine or muscarine. A delta-agonist, enkephalin [D-PEN2.5] (PDPDE), did not show any significant effect. On the other hand, a selective mu-receptor antagonist, cyprodime, increased ACh release evoked by EFS at 1 Hz, but not at 10 Hz. After the autoreceptors were blocked, cyprodime increased EFS-evoked ACh release also at 10 Hz. The selective kappa-receptor antagonist, nor-binaltorphimine, did not affect ACh release in the absence or presence of atropine. The results suggest that endogenous opioid(s) inhibits ACh release by activating mu-, but not kappa- and delta-receptors in the LMMP of guinea pig ileum and that the inhibitory effect of endogenous opioid(s) in the ACh release is important when muscarinic autoinhibition mechanism does not fully work.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1998

Inhibitory effect of endomorphin-1 and -2 on acetylcholine release from myenteric plexus of guinea pig ileum.

Endomorphin-1 and -2, putative endogenous ligands for the mu-opioid receptor, inhibited acetylcholine (ACh) release evoked by electrical field stimulation (EFS) at 1 Hz, which partially activates muscarinic autoreceptors, but not at 10 Hz, which fully activates muscarinic autoreceptors, in longitudinal muscle with the myenteric plexus (LMMP) preparations of guinea pig ileum. After blockade of autoinhibition by atropine, the peptides also inhibited EFS-evoked ACh release at 10 Hz. The inhibitory effects on ACh release were abolished by the mu-opioid antagonist cyprodime. These results suggest that endomorphin-1 and -2 inhibit ACh release from LMMP preparations of guinea pig ileum and that the mechanism of the inhibition must have a component in common with muscarinic autoinhibition.

Acetylcholine↗
PubMed1998

Surgical correction of trigonocephaly: theoretical basis and operative procedures.

Trigonocephaly involves premature fusion of both the metopic suture and the sutures in the skull base. Surgical treatment by opening of the prematurely fused metopic suture and expansion of the anterior cranial base by creating "neosutures" was used to treat three children with trigonocephaly. The combination of lateral canthal advancement and radical forehead remodeling achieved excellent results. These procedures can also prevent the development of midface hypoplasia such as hypotelorism. The two younger patients, aged 0 and 6 months, achieved rapid bone growth in the defects and normalization of intercanthal and interpupillary distances. The older patient, aged 8 years, retained some skull defects at follow-up. The optimal age for surgery is 3-6 months, which allows good cosmetic results and minimizes visual repercussions with relatively low perioperative risks.

Cephalometry↗