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Biomedical subjects

S Iwasaki

Publications and source records attributed to S Iwasaki.

At least 37 records · Page 2Linked to original sources
PubMed2001

Reversible nephrotic syndrome in a patient with amyloid A amyloidosis of the kidney following methicillin-resistant Staphylococcus aureus infection.

A common form of methicillin-resistant Staphylococcus aureus (MRSA) associated glomerulonephritis is either an endocapillary proliferative glomerulonephritis or a crescentic glomerulonephritis. This report describes the development of reversible nephrotic syndrome following MRSA infection in a patient with amyloid A amyloidosis. The patient had been diagnosed as having rheumatoid arthritis for 50 years. Suppurative arthritis due to MRSA became complicated 2 years prior to admission to our hospital. In the meantime, a nonnephrotic-range proteinuria developed. Two weeks before admission, nephrotic syndrome developed. The serum creatinine level remained unchanged throughout the course, but common features characteristic of MRSA-associated glomerulonephritis were observed in this patient, such as elevated serum IgG and IgA levels. A renal biopsy specimen showed glomerular amyloid A amyloidosis of a nodular type, infiltrated mononuclear cells in the mesangium, deposition of IgG, IgA, and C3, and swelling of glomerular endothelial cells. There were no crescentic glomeruli. Following surgical eradication of the MRSA focus in the right knee joint, nephrotic syndrome disappeared. Hence, it was highly possible that MRSA infection induced a reversible nephrotic syndrome by causing reversible injuries to glomerular endothelial cells. The description of this case serves to illustrate the range of MRSA infections that may cause various forms of glomerulonephritides.

Aged↗
PubMed2001

[Comparative survey of cardiac arrests during anesthesia and surgery in the 1980 s and 1999 s].

A survey of unexpected cardiac arrests, excluding those associated with cardiac surgery, that had occurred during anesthesia and surgery in the period 1980-1999 was conducted. There was no significant difference between the number of such cardiac arrests that occurred in the 1980 s (29/36,159, 0.080%) and the number in the 1990 s (33/37,643, 0.088%). According to the classification by Keenan et al., there were 3 cases (0.0083%) in the 80 s and 4 cases (0.0106%) in the 90 s that occurred due to anesthetic management. Cardiac arrests due to surgery itself significantly decreased from 21 cases in the 80 s to 6 cases in the 90 s, probably due to proper treatment for massive bleeding, a decrease in the number of cases of anaphylactic shock, and the development of novel anesthetics. Conversely, cardiac arrests due to preoperative conditions of the patients significantly increased from 5 cases in the 80 s to 23 cases in the 90 s. This increase seems to be due to an increase in the number of severe and multiple injuries and an increase in complicated major surgery. The increase in number of cases due to preoperative conditions also depends on coronary spasm and cardiac conduction insufficiency. Taking into consideration the improvement in intraoperative monitoring and the development of novel anesthetics in the 90 s, greater efforts should be made by anesthesiologists to reduce the incidence of cardiac arrest due to anesthetic management, and preoperative evaluation of surgical patients needs to be reconsidered.

Anesthesia↗
PubMed2001

[The effect of lidocaine on the bispectral index during anesthesia induction with propofol].

We investigated the effect of premixing lidocaine with propofol on a bispectral index (BIS) during propofol infusion. We studied 40 adult patients given mixture of 1% propofol 20 ml with 2 ml of normal saline (control group) or 2% lidocaine (lidocaine group) infused at 2 ml.kg-1.hr-1 for 10 minutes. Heart rate, mean arterial pressure, and BIS were measured every minute. The addition of lidocaine to propofol reduced the incidence of injection pain from 85% to 10% but did not change the induction time. Propofol significantly decreased mean arterial pressure and BIS but there was no difference between the groups. In conclusion, premixing lidocaine with propofol reduces injection pain without affecting the hypnotic effect.

Adult↗
PubMed2001

[Effects of volume and concentration of lidocaine on epidural anesthesia].

We studied 40 patients scheduled for gynecological surgery to evaluate the effects of volume and concentration of lidocaine on epidural anesthesia. We injected lidocaine 300 mg as 1% (30 ml) or 2% (15 ml) through epidural catheter at L 1/2. There was no significant difference in the spread of sensory blockade (cold and pain) and the Bromage scale between the two lidocaine solutions. This result suggests that volume and concentration of lidocaine do not affect the effects of epidural anesthesia.

Adult↗
PubMed2001

[Efficacy of bispectral index for anesthetic management of combined off-pump coronary artery bypass grafting and abdominal aortic aneurysm replacement].

A 57-year-old female patient underwent combined off-pump coronary artery bypass grafting and abdominal aortic aneurysm replacement. Anesthesia was maintained with propofol, fentanyl, and thoracic epidural anesthesia. Propofol doses were adjusted to maintain bispectral index (BIS) between 40-60. Despite the remarkable hemodynamic changes, BIS remained stable at about 50 during the surgery. The average dose of propofol was 3.3 mg.kg-1.hr-1. The patient awoke an hour after the surgery and was extubated 1.5 hours thereafter. This case report suggests that BIS is a useful index to determine the depth of anesthesia during surgeries which induce marked hemodynamic changes.

Anesthesia↗
PubMed2001

Development of "Standards for the Evaluation of Hospital Infection Control Policies and Procedures, the Second Version".

The Japan Society for Quality in Health Care (JSQua) created "Standards for the Evaluation of Hospital Infection Control Policies and Procedures, the First Version" in 1998 and carried out third-party surveys. Through the experience of those surveys, we revised the standards and created a second version in 1999. The surveyors felt that in using the second version of the standards it would be easier to evaluate the quality of hospital care and that these standards would be more widely applied.

Cross Infection↗
PubMed2000

Erythropoietin inhibits calcium-induced neurotransmitter release from clonal neuronal cells.

Erythropoietin (EPO) and EPO receptor (EPO-R) are expressed in the brain but their neuronal functions are not yet clarified. The effects of EPO on neurosecretion were studied using clonal rat pheochromocytoma PC12 cells. EPO suppressed Ca(2+)-induced dopamine release from PC12 cells in a concentration- and time-dependent manner. Inhibition was also produced by an EPO mimetic peptide 1 (EMP1), a small synthetic peptide agonist of EPO-R, but not by its inactive analogue in which Cys residues were substituted with Ser. Inhibition was abolished by genistein but not by genistin. EPO and EMP1 induced autophosphorylation of Janus kinase 2 (JAK 2), a tyrosine kinase that associates with EPO-R, and dephosphorylation of GAP-43 in a tyrosine kinase-dependent fashion. These results suggest that EPO suppresses neurotransmitter release through activation of EPO-R linked to JAK2.

Animals↗
PubMed2000

Effect of maternal separation on feeding behavior of rats in later life.

Effects of maternal separation on feeding behavior, particularly on rebound hyperphagia, in adult rats were examined. Time-restricted scheduled feeding (2 h per day for 6 days), was given at the age of 3, 6, 9 or 12 weeks in rats that were maternal separated from postnatal days (PD) 1-21 and control rats. Following the time-restricted scheduled feeding, rats were fed freely for 24 h (rebound hyperphagia). Body weight, daily normal food consumption and food consumption during time-restricted scheduled feeding and rebound hyperphagia were measured. Body weight of 3-week-old maternally separated rats were less than those of control rats. There was no significant difference in normal daily food consumption. Food consumption during rebound hyperphagia was significantly increased in 6- to 9-week-old female maternally separated rats, but there was no difference observed in males. Postnatal maternal separation enhanced rebound hyperphagia of female rats in later life. These results indicate that postnatal maternal separation made rats more vulnerable to the development of abnormal feeding behavior in response to food restriction in later life.

Aging↗
PubMed2000

Developmental changes in calcium channel types mediating central synaptic transmission.

Multiple types of high-voltage-activated Ca(2+) channels trigger neurotransmitter release at the mammalian central synapse. Among them, the omega-conotoxin GVIA-sensitive N-type channels and the omega-Aga-IVA-sensitive P/Q-type channels mediate fast synaptic transmission. However, at most central synapses, it is not known whether the contributions of different Ca(2+) channel types to synaptic transmission remain stable throughout postnatal development. We have addressed this question by testing type-specific Ca(2+) channel blockers at developing central synapses. Our results indicate that N-type channels contribute to thalamic and cerebellar IPSCs only transiently during early postnatal period and P/Q-type channels predominantly mediate mature synaptic transmission, as we reported previously at the brainstem auditory synapse formed by the calyx of Held. In fact, Ca(2+) currents directly recorded from the auditory calyceal presynaptic terminal were identified as N-, P/Q-, and R-types at postnatal day 7 (P7) to P10 but became predominantly P/Q-type at P13. In contrast to thalamic and cerebellar IPSCs and brainstem auditory EPSCs, N-type Ca(2+) channels persistently contribute to cerebral cortical EPSCs and spinal IPSCs throughout postnatal months. Thus, in adult animals, synaptic transmission is predominantly mediated by P/Q-type channels at a subset of synapses and mediated synergistically by multiple types of Ca(2+) channels at other synapses.

2-Amino-5-phosphonovalerate↗
PubMed2000

A new model for investigating hair cell degeneration in the guinea pig following damage of the stria vascularis using a photochemical reaction.

We have established a new model for investigating the relationship between cochlear lateral wall damage and sensory cell degeneration in guinea pigs by using a photochemical reaction between the systemic injection of Rose Bengal (RB) and controlled green light irradiation to the cochlea. The photochemical reaction produced a reactive oxygen species, which then damaged the endothelium. This triggered platelet adhesion and aggregation at the site of endothelial injury to produce thrombi and affect microcirculation in the lateral wall at the site of irradiation. Changes were studied under a scanning electron microscope (SEM), and compound action potentials (CAP) were measured. SEM observations after tangential illumination of the cochlear wall revealed degeneration of the stria vascularis (SV). Specific morphological findings at 24 h included delayed degeneration of the outer hair cells concurrent with a significant increase in the CAP. Based on these findings, we suggest that degeneration of the SV was a direct result of the photochemical reaction, but CAP changes and sensory hair cell damage were secondarily caused by SV degeneration.

Action Potentials↗
PubMed2000

Nerve growth factor-induced phosphorylation of SNAP-25 in PC12 cells: a possible involvement in the regulation of SNAP-25 localization.

Synaptosomal-associated protein of 25 kDa (SNAP-25), a t-SNARE protein essential for neurotransmitter release, is phosphorylated at Ser187 following activation of cellular protein kinase C by treatment with phorbol 12-myristate 13-acetate. However, it remains unclear whether neuronal activity or an endogenous ligand induces the phosphorylation of SNAP-25. Here we studied the phosphorylation of SNAP-25 in PC12 cells using a specific antibody for SNAP-25 phosphorylated at Ser187. A small fraction of SNAP-25 was phosphorylated when cells were grown in the absence of nerve growth factor (NGF). A brief treatment with NGF that was enough to activate the mitogen-activated protein kinase signal transduction pathway did not increase the phosphorylation of SNAP-25; however, phosphorylation was up-regulated after a prolonged incubation with NGF. Up-regulation was transitory, and maximum phosphorylation (a fourfold increase over basal phosphorylation) was achieved between 36 and 48 h after the addition of NGF. Immunofluorescent microscopy showed that SNAP-25 was localized primarily in the plasma membrane, although a significant population was also present in the cytoplasm. Quantitative microfluorometry revealed that prolonged treatment with NGF resulted in a preferential localization of SNAP-25 in the plasma membrane. A mutational study using a fusion protein with green fluorescent protein as a tag indicated that the point mutation of Ser187 to Ala abolished the NGF-dependent relocalization. A population of SNAP-25 in the plasma membrane was not increased by a point mutation at Ser187 to Glu; however, it was increased by prolonged treatment with NGF, indicating that the SNAP-25 phosphorylation is essential, but not sufficient, for the NGF-induced relocation to the plasma membrane. Our results suggest a close temporal relationship between the up-regulation of SNAP-25 phosphorylation and its relocation, and NGF-induced differentiation of PC12 cells.

Animals↗
PubMed2000

Antifungal, antimitotic and anti-HIV-1 agents from the roots of Wikstroemia indica.

With guidance of Pyricularia oryzae bioassay, daphnoretin (1), (+)-nortrachelogenin (2), genkwanol A (3), wikstrol A (4), wikstrol B (5) and daphnodorin B (6) were isolated from the roots of Wikstroemia indica. Compounds 1-6 induced morphological deformation of P. oryzae mycelia with MMDC values of 68.4 +/- 1.3, 31.3 +/- 1.8, 45.8 +/- 0.5, 70.1 +/- 2.4, 52.3 +/- 0.9 and 73.7 +/- 1.6 microM, respectively. Compounds 3-6 showed moderate activity against microtubule polymerization with IC50 values of 112 +/- 4, 131 +/- 3, 184 +/- 6 and 142 +/- 2 microM in vitro, respectively. Compounds 2, 3, 5 and 6 were moderately active against HIV-1 in vitro. The findings of bioactivity of 1-6 support the antifungus, antimitosis and anti-HIV-1 uses for W. indica roots.

Anti-HIV Agents↗
PubMed2000

Enhancement pattern of normal extraocular muscles in dynamic contrast-enhanced MR imaging with fat suppression.

PURPOSE: To evaluate the internal structure of normal extraocular muscles on fat-suppressed dynamic contrast-enhanced MR imaging. MATERIAL AND METHODS: Ten subjects were examined using fat-suppressed dynamic contrast-enhanced MR imaging. We evaluated the enhancement pattern (C-shaped or ring-like) of extraocular muscles and quantified the maximum ratios of enhancement (Rmax) and maximum ratios of signal increase (Vmax). We also quantified Rmax and Vmax in the central and peripheral portions of medial rectus muscles. RESULTS: In the early phase of dynamic contrast-enhanced MR imaging, a C-shaped or ring-like pattern was observed in 100% of inferior rectus, 95% of medial rectus, 55% of superior rectus, 20% of lateral rectus, and 15% of superior oblique muscles. Overall mean Rmax and Vmax values showed statistically significant differences to the temporal muscles. For the peripheral portion of medial rectus muscles, mean Rmax and Vmax values were greater than for the central portion. CONCLUSION: Using fat-suppressed dynamic contrast-enhanced MR imaging, the C-shape or ring-like internal structure of the extraocular muscles could be visualized, and were considered to reflect their structure of orbital and global layers. Potential usefulness of the fat-suppressed dynamic contrast-enhanced MR imaging for detecting pathological status is suggested.

Adipose Tissue↗
PubMed2000

Two distinct mechanisms underlie the stimulation of neurotransmitter release by phorbol esters in clonal rat pheochromocytoma PC12 cells.

Phorbol ester treatment induces the phosphorylation of SNAP-25 at Ser(187) and the potentiation of Ca(2+)-induced dopamine (DA) and acetylcholine (Ach) release from PC12 cells. In order to evaluate the functional consequences of phosphorylation, quantitative analysis was carried out using an anti-phosphopeptide antibody that specifically recognizes SNAP-25 phosphorylated at Ser(187). DA and ACh release, assayed in low-K(+) as well as high-K(+) solution, increased by treating the cells with phorbol-12-myristate-13-acetate (PMA); however, the stimulation of high-K(+)-dependent release occurred at lower concentrations and with shorter exposures to PMA than that of the basal release in low-K(+)-solution. The PMA-induced phosphorylation of SNAP-25 did not correlate with the potentiation of high-K(+)-dependent neurotransmitter release. The potentiation of high-K(+)-dependent DA release by phorbol 12,13-diacetate (PDA), a water soluble phorbol ester, almost completely disappeared within 1 min after washing PDA in the presence of okadaic acid, conditions under which the phosphorylation of SNAP-25 persisted for at least 15 min. PMA-induced phosphorylation of SNAP-25 was inhibited by staurosporine, however, the potentiation of high-K(+)-dependent DA release was suppressed only partially. These results indicate that protein kinase activation does not account for a large fraction of the phorbol ester-induced potentiation of depolarization-dependent neurotransmitter release from PC12 cells.

Acetylcholine↗
PubMed2000

Production of live calves derived from embryonic stem-like cells aggregated with tetraploid embryos.

To date, cloned farm animals have been produced by nuclear transfer from embryonic, fetal, and adult cell types. However, mice completely derived from embryonic stem (ES) cells have been produced by aggregation with tetraploid embryos. The objective of the present study was to generate offspring completely derived from bovine ES-like cells. ES-like cells isolated from the inner cell mass of in vitro-produced embryos were aggregated with tetraploid bovine embryos generated by electrofusion at the 2-cell stage. A total of 77 embryo aggregates produced by coculture of two 8-cell-stage tetraploid embryos and a clump of ES-like cells were cultured in vitro. Twenty-eight of the aggregates developed to the blastocyst stage, and 12 of these were transferred to recipient cows. Six calves representing 2 singletons and 2 sets of twins were produced from the transfer of the chimeric embryos. Microsatellite analysis for the 6 calves demonstrated that one calf was chimeric in the hair roots and the another was chimeric in the liver. However, unfortunately, both of these calves died shortly after birth. Two of the placentae from the remaining pregnancies were also chimeric. These results indicate that the bovine ES-like cells used in these studies were able to contribute to development.

Animals↗
PubMed2000

Carbon dioxide absorbents containing potassium hydroxide produce much larger concentrations of compound A from sevoflurane in clinical practice.

UNLABELLED: We investigated the concentrations of degraded sevoflurane Compound A during low-flow anesthesia with four carbon dioxide (CO(2)) absorbents. The concentrations of Compound A, obtained from the inspiratory limb of the circle system, were measured by using a gas chromatograph. In the groups administered 2 L/min fresh gas flow with 1% sevoflurane, when the conventional CO(2) absorbents, Wakolime(TM) (Wako, Tokyo, Japan) and Drägersorb(TM) (Dräger, Lübeck, Germany), were used, the concentrations of Compound A increased steadily from a baseline to 14.3 ppm (mean) and 13.2 ppm, respectively, at 2 h after exposure to sevoflurane. In contrast, when the other novel types of absorbents containing decreased or no potassium hydroxide/sodium hydroxide, Medisorb(TM) (Datex-Ohmeda, Louisville, CO) and Amsorb(TM) (Armstrong, Coleraine, Northern Ireland), were used, Compound A remained at baseline (<2 ppm) throughout the study. In the groups administered 1 L/min fresh gas flow with 2% sevoflurane, Wakolime(TM) and Drägersorb(TM) produced much larger concentrations of Compound A (35.4 ppm and 34.2 ppm, respectively) at 2 h after exposure to sevoflurane. Medisorb(TM) showed measurable concentrations of Compound A (8.6 ppm at 2 h), but they were significantly smaller than those produced by the two conventional absorbents. In contrast, when Amsorb(TM) was used, Compound A concentrations remained at baseline throughout the study period. IMPLICATIONS: Carbon dioxide absorbents containing potassium hydroxide/sodium hydroxide produce much larger concentrations of Compound A from sevoflurane in clinical practice. An absorbent containing neither potassium hydroxide nor sodium hydroxide produces the smallest concentrations of Compound A.

Absorption↗
PubMed2000

Immunohistochemical studies on vascular endothelial growth factor and platelet endothelial cell adhesion molecule-1/CD-31 in islet transplantation.

Neovascularization may be necessary for better and longer function of transplanted islets. Vascular endothelial growth factor (VEGF) is known to be one of the most important factors of angiogenesis. Recently, VEGF was reported to be expressed in islets of normal pancreas. We studied the expression of VEGF and neovascularization related peptides in transplanted islets. To determine the angiogenic microcapillary, immunochemical staining was performed for Factor VIII-related antigen (von Willebrand factor [vWF]) and platelet endothelial cell adhesion molecule-1/CD31 (PECAM-1), both of which are known as markers of the angiogenic microvessel. Transplantable islets were isolated from Lewis rats (8-10 weeks of age) by discontinuous dextran gradient after collagenase digestion. Seven to twelve hundred islets were injected into the portal vein (IPV group, n = 7) or transplanted into subnephrocapsular cavity (SNC, n = 12) of the same descent rats. In the IPV group, the liver was resected 1 hour, 1 week, or 4 weeks after transplantation (Tx). In the SNC group, the kidney was resected 1, 3, 7, or 28 days after Tx. Each tissue was fixed in formaldehyde and embedded in paraffin. Serial 4-microm slices were immunostained for insulin, VEGF, PECAM-1, or vWF using specific antibodies. In IPV group, insulin-positive cells were VEGF positive as were in the normal pancreas at all time points. Islets of 1 hour after Tx were barely PECAM-1 positive as were in normal pancreas, but islets became weakly stained at 7 and 28 days after Tx. In vWF staining, transplanted islets showed stronger staining than those in the normal pancreas. In SNC group, VEGF was also stained in insulin-positive cells at 1, 3, 7, and 28 days. In PECAM-1 staining, islets of 1 day after Tx were barely stained as were in normal pancreas. However, the staining was increasingly enhanced from 3 to 7 days and then appeared weakened at 28 days after Tx. In vWF staining, islets were always vWF positive, as was seen in IPV group. This study revealed that PECAM-1 appeared in islets after islet Tx, suggesting that neovascularization occurs within the islet grafts. On the other hand, VEGF of transplanted islet did not obviously vary with time. Enhancement of the neovascularization may lead to better results of islet Tx.

Animals↗