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Takeshi Usami

Publications and source records attributed to Takeshi Usami.

At least 19 recordsLinked to original sources
PubMed2006

Altered gene activity correlated with long-term memory formation of conditioned taste aversion in Lymnaea.

The pond snail Lymnaea stagnalis is capable of learning conditioned taste aversion (CTA) and then consolidating that learning into long-term memory (LTM) that persists for at least 1 month. LTM requires de novo protein synthesis and altered gene activity. Changes in gene activity in Lymnaea that are correlated with, much less causative, memory formation have not yet been identified. As a first step toward rectifying this situation, we constructed a cDNA microarray with mRNAs extracted from the central nervous system (CNS) of Lymnaea. We then, using this microarray assay, identified genes whose activity either increased or decreased following CTA memory consolidation. We also identified genes whose expression levels were altered after inhibition of the cyclic AMP response element-binding protein (CREB) that is hypothesized to be a key transcription factor for CTA memory. We found that the molluscan insulin-related peptide II (MIP II) was up-regulated during CTA-LTM, whereas the gene encoding pedal peptide preprohormone (Pep) was down-regulated by CREB2 RNA interference. We next examined mRNAs of MIP II and Pep using real-time RT-PCR with SYBR Green. The MIP II mRNA level in the CNS of snails exhibiting "good" memory for CTA was confirmed to be significantly higher than that from the CNS of snails exhibiting "poor" memory. In contrast, there was no significant difference in expression levels of the Pep mRNA between "good" and "poor" performers. These data suggest that in Lymnaea MIP II may play a role in the consolidation process that forms LTM following CTA training.

Analysis of Variance↗
PubMed2006

Polynocturia in chronic kidney disease is related to natriuresis rather than to water diuresis.

BACKGROUND: Nocturnal polyuria has been well known in renal insufficiency. Recently, we found that as renal function deteriorated in chronic kidney disease (CKD), natriuresis was enhanced during the night with nocturnal blood pressure elevation. In the present study, we investigated whether nocturnal polyuria in CKD was due to the inability to concentrate urine, as previously proposed, or based on osmotic diuresis mainly by natriuresis. METHODS: In 27 CKD patients, circadian rhythms of urinary sodium, potassium, urea and osmolar excretion rates (U(Na)V, U(K)V, U(urea)V, U(osm)V) as well as of urinary volume (V) and free-water clearance (C(H(2)O)) were estimated during both daytime (6:00 to 21:00) and nighttime (21:00 to 6:00). Then, the night/day ratios of these parameters were analysed in relation to creatinine clearance (C(cr)) as a marker of glomerular filtration rate. RESULTS: C(cr) had significantly negative relationships with night/day ratios of V (R = -0.69; P < 0.0001), U(osm)V (R = -0.54; P = 0.004) and U(Na)V (R = -0.63; P = 0.0005), but no correlation with night/day ratios of C(H(2)O) (R = -0.33; P = 0.1), U(K)V (R = -0.29; P = 0.1) or U(urea)V (R = -0.31; P = 0.1). Linear and multiple regression analysis identified nocturnal natriuresis rather than urea excretion as an independent determinant of nocturia. CONCLUSION: As renal function deteriorated, nocturnal polyuria was seen, being consistent with classical recognition. Furthermore, this increase in nocturnal urine volume seemed related to osmotic diuresis mainly by natriuresis rather than to water diuresis or urea excretion.

Blood Pressure↗
PubMed2006

Proposal for mapping renal failure in Japan and its application for strategy to arrest endstage renal disease.

Remarkable regional differences in the annual incidence of endstage renal disease (ESRD) was found within Japan, which has a relatively homogeneous ethnic composition. In addition, there existed no regional difference in the incidence of ESRD due to polycystic kidney disease, the major genetic disorder of the kidneys. These findings suggest that the presence of factors other than genetic disposition contribute to the differences. On the other hand, there were similar regional variations in the incidences of ESRD between two causes of ESRD: chronic glomerulonephritis and diabetic nephropathy. Because it is unlikely that the regional distribution of underlying disease incidence and the disease-specific progression rate would be similar for two different causes, this observation suggests that factors governing the progression rate, which operate commonly for all causes of ESRD but differ among regions, may play an important role in generating the regional differences. Finally, we examined regional differences in the amounts of inhibitors of the renin-angiotensin system used, especially angiotensin-converting enzyme (ACE) inhibitors, in our search for an explanation of the regional differences in ESRD dynamics. Among antihypertensive agents examined, only ACE inhibitors were negatively correlated with the annual incidence of ESRD. The renal protective effects of ACE inhibitors have been established by results with animal models of progressive nephropathy and by large-scale clinical trials. Our epidemiological results for Japan as a whole show the same protective effects still more convincingly from a different approach. It is not completely clear yet at present, however, how regional variations in the incidence of ESRD are generated. If we could identify in future the factors that contribute to the regional differences, strategies for the treatment of renal disease will become available from different angles. Thus, much effort will be encouraged for the further analysis of regional differences in ESRD dynamics.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2006

An overview of regular dialysis treatment in Japan (as of 31 December 2004).

A statistical survey of 3932 nationwide hemodialysis (hereafter, dialysis) facilities was carried out at the end of 2004, and 3882 facilities (98.73%) responded. The population undergoing dialysis at the end of 2004 was 248 166, an increase of 10 456 patients (4.4%) from that at the end of 2003. The number of dialysis patients per million people was 1943.5. The crude death rate of dialysis patients from the end of 2003 to the end of 2004 was 9.4%. The mean age of patients who underwent dialysis in 2004 was 65.8 years, and that of the total dialysis population was 63.3 years. The percentage distribution of patients who underwent dialysis according to a newly underlying disease showed that 41.3% of patients had diabetic nephropathy and 28.1% had chronic glomerulonephritis. The frequency of calcium carbonate use for dialysis patients was 75.1% and that of sevelamer hydrochloride use was 26.2%. The frequency of sevelamer hydrochloride use does not necessarily have a strong correlation with the dose of calcium carbonate. Patients who received high doses of sevelamer hydrochloride tended to have a low concentration of arterial blood HCO(3-). Approximately 15% of dialysis patients used an intravenous vitamin D preparation, generally maxacalcitol. The longer the patients had been on dialysis, the higher the frequency of use of an intravenous vitamin D preparation. When the concentration of serum intact parathyroid hormone (PTH) was more than 200 pg/mL, the frequency of use of an orally administered vitamin D preparation decreased; but that of intravenous vitamin D preparation increased. The percentage of dialysis patients who received percutaneous ethanol injection therapy (PEIT) was 1.4%. The percentage was more than 50% in the patients who had been on dialysis for more than 10 years. The percentage of patients who received PEIT again was 35.0%. The percentage of patients who had been on hemodialysis for more than 10 years and received PEIT again was more than 50%.

Adolescent↗
PubMed2005

Oligonucleotide-based microarray analysis of retinoic acid target genes in the protochordate, Ciona intestinalis.

Oligonucleotide-based microarray analyses were carried out to identify retinoic acid target genes in embryos of the ascidian Ciona intestinalis. Of 21,938 spots, 50 (corresponding to 43 genes) showed over twofold up-regulation in retinoic acid-treated tail bud embryos. In situ hybridization verified retinoic acid-induced up-regulation of 23 genes. Many of them were expressed in the anterior tail region, where a retinaldehyde dehydrogenase homolog is expressed. Homologs of vertebrate genes involved in neurogenesis and/or neuronal functions (e.g., COUP-TF, Ci-Hox1, and SCO-spondin) were expressed in the central nervous system of Ciona embryos, and activated by retinoic acid. Genes encoding transcription factors (e.g., Ci-lmx1.2, vitamin D receptor, and Hox proteins) and apoptosis-related proteins (e.g., transglutaminase and an apoptosis-inducing factor homolog) were also activated by retinoic acid. Simultaneous treatment of embryos with retinoic acid and puromycin revealed a few direct targets, including genes encoding Ci-Hox1, Ci-Cyp26, and an Rnf126-like ring finger protein.

Animals↗
PubMed2005

Different regional dynamics of end-stage renal disease in Japan by different causes.

BACKGROUND: We recently showed that there were clear regional differences in the dynamics of end-stage renal disease (ESRD) within Japan, which has an ethnically homogenous population. We speculate on the reason for these regional differences by correlating the regional distributions in the incidence of ESRD due to each of the following individual causes of ESRD: chronic glomerulonephritis (CGN), diabetic nephropathy (DMN) and polycystic kidney disease (PKD). METHODS: The number of ESRD patients entering maintenance dialysis therapy due to individual causes of renal disease in each prefecture was reported annually for a 6-year period by the Japanese Society for Dialysis Therapy. After combining data from several prefectures into 11 geopolitical regions in Japan, the mean annual incidence of ESRD across the 11 regions was correlated among the three causes of ESRD. RESULTS: There were significant regional differences in the incidence of ESRD due to CGN (P<0.0001) and DMN (P=0.0015), the distributions of which were similar to each other across the 11 regions. In contrast, no regional differences were found in the incidence of ESRD due to PKD (P=0.6) as the major genetic disorder of the kidneys, suggesting that genetic backgrounds are relatively uniform throughout Japan. The regional distributions due to PKD were not correlated with those due to other causes: CGN and DMN. CONCLUSION: Risk factors common to nephropathy progression, rather than an underlying disease incidence and genetic predisposition, might contribute to regional differences in the overall ESRD incidence in Japan. Other possibilities such as the prevalence of underlying diseases, and acceptance or rejection rates into treatment programmes must be considered further for better explanations.

Chronic Disease↗
PubMed2004

Powerful red-green-blue laser source pumped with a mode-locked thin disk laser.

We present a red-green-blue laser source with average powers of 8 W in the red, 23 W in the green, and 10.1 W in the blue. The entire pump power for the nonlinear conversion stages is provided by a single laser oscillator without any amplifier stages. Our system does not require any synchronized cavities, and all nonlinear crystals except one are critically phase matched at room temperature.

Journal Article↗
PubMed2004

Characteristics and primary structure of a galectin in the skin mucus of the Japanese eel, Anguilla japonica.

The characteristics and primary structure of AJL-1, one of the lectins in the skin mucus of the Japanese eel (Anguilla japonica), were examined. This lectin exhibited beta-galactoside specific activity in a Ca2+ independent manner. We previously reported that its molecular mass was 16,091Da, although it was approximately 30 kDa as determined by gel filtration, indicating that it is a homodimer having non-covalent bonds. This lectin was composed of 142 amino acid residues having no half-cystinyl residues, and showed homology to members of the galectin family, especially to proto-type galectins. Gene expression of this lectin was detected in skin only, and relative expression was high in an individual that exhibited resistance to infectious disease. AJL-1 showed agglutinating activity against pathogenic bacteria, Streptococcus difficile. This suggests that AJL-1 functions as an important defensive factor at the body surface.

Amino Acid Sequence↗
PubMed2004

In vitro effects of steroid hormones on IgM-secreting cells and IgM secretion in common carp (Cyprinus carpio).

The effects of steroid hormones on in vitro IgM-secreting cells (IgMSC) and IgM secretion by lymphocytes of the lymphoid organs in common carp, Cyprinus carpio were examined by ELISPOT and ELISA assay, respectively. Cells isolated from peripheral blood (PB), spleen and head kidney were cultured for 12, 24 and 48 h either in the absence or in the presence of steroid hormones, i.e. cortisol, testosterone, 11-ketotestosterone (11-KT), and estradiol-17beta (E(2)) at doses of 1, 10 and 100 ng/ml. Cortisol reduced the IgMSC numbers and IgM secretion by cells from all organs. In addition, cortisol induced apoptosis in lymphocytes from all organs. High dose of testosterone showed tissue-specific functions; it reduced the number of IgMSC and amount of IgM secretion by cells from spleen and head kidney, but not in PB, though IgM secretion was suppressed. However, no effects of sex steroids were observed in this study. The results show that sex-specific steroid hormones may have no immunosuppressive effects in common carp.

Animals↗
PubMed2004

Cryptochromes and phytochromes synergistically regulate Arabidopsis root greening under blue light.

To increase their fitness, plants sense ambient light conditions and modulate their developmental processes by utilizing multiple photoreceptors such as phytochrome, cryptochrome and phototropin. Even roots, which are normally not exposed to light, express photoreceptors and can respond to light by developing chloroplasts. In the present study, root greening was observed in Arabidopsis thaliana. Seedlings were grown under monochromatic light and chlorophyll levels in the roots were determined. It was found that blue light was far more effective at inducing chloroplast development in Arabidopsis roots than was red light, and this response was under the control of a strong synergistic interaction between phytochromes and cryptochromes. As expected, the cry1 mutant was deficient in this response. Interestingly, the phyAphyB double mutant failed to respond to blue light under these conditions. This strongly suggests that either phytochrome A or phytochrome B, in addition to cryptochrome, was required for this blue light response. It was further demonstrated that the expression of photosynthetic genes was regulated in the same way. Dichromatic irradiation experiments indicated that this interaction depends on the level of phyB P(FR). Analysis of the cop1, det1 and hy5 mutants indicated that the corresponding factors were involved in the response.

Arabidopsis↗
PubMed2004

Nocturnal blood pressure is elevated with natriuresis and proteinuria as renal function deteriorates in nephropathy.

BACKGROUND: We reported that patients with sodium sensitive type of hypertension exhibited the lack of nocturnal fall in blood pressure with enhanced natriuresis during night. Sodium sensitivity is caused by diminished glomerular filtration capability and/or augmented tubular reabsorption of sodium, and seems tightly linked with glomerular capillary hypertension. In the present study, we investigated the relationship between glomerular filtration rate and circadian rhythms of these parameters in patients with glomerulopathy. METHODS: Twenty six patients (15 men and 11 women; aged 17 to 72 years; mean age 47 +/- 3 years), whose diagnosis was confirmed as glomerulopathy with renal biopsy, were studied during hospitalization. Ambulatory blood pressure for 24 hours was monitored, while urinary samples were collected for both daytime (6:00 a.m. to 9:00 p.m.) and nighttime (9:00 p.m. to 6:00 a.m.) to estimate circadian rhythms of urinary sodium and protein excretion rates (UNaV, UproV). Then night/day ratios of mean arterial blood pressure (MAP), UNaV, and UproV were analyzed in relation to 24-hour creatinine clearance as a marker of glomerular filtration rate. RESULTS: Serum creatinine and creatinine clearance were 1.1 +/- 0.1 mg/dL and 89 +/- 7 mL/min/1.73 m2. There were significant day-night differences in MAP (96 +/- 2 mm Hg vs. 92 +/- 2 mm Hg; P= 0.006), UNaV (6.7 +/- 0.9 mmol/hour vs. 3.6 +/- 0.3 mmol/hour; P= 0.003), and UproV (161 +/- 27 mg/hour vs. 128 +/- 28 mg/hour; P= 0.02). Creatinine clearance had significantly negative relationships with night/day ratios of MAP (r=-0.49; P= 0.01), UNaV (r=-0.43; P= 0.03,) and UproV (r=-0.41; P= 0.04). In addition, night/day ratio of MAP had significantly positive relationships with night/day ratios of UNaV (r= 0.49; P= 0.01) and UproV (r= 0.45; P= 0.02). CONCLUSION: Our results show that as renal function deteriorates in glomerulopathy the nocturnal dip in blood pressure is lost, resulting in enhanced urinary sodium and protein excretions during night. These findings are compatible with our proposal that impaired natriuresis during daytime makes nocturnal blood pressure elevated to compensate for diminished natriuresis by pressure natriuresis. We speculate that nocturnal glomerular capillary hypertension contributes, at least in part, to enhanced urinary sodium and protein excretions during night.

Adult↗
PubMed2003

Complement fragment C4d deposition in peritubular capillaries in acute humoral rejection after ABO blood group-incompatible human kidney transplantation.

BACKGROUND: Acute humoral rejection (AHR) is the most important risk factor for early graft loss in ABO-incompatible (ABO-i) kidney transplantation (RTx). The pathogenesis and diagnostic criteria for AHR after ABO-i RTx remain unclear. Complement fragment C4d deposition in peritubular capillaries (PTC), which is a sensitive indicator for activation of the classical complement pathway, was studied to establish the pathologic diagnostic indicator of AHR. METHODS: Forty-four graft biopsy specimens from 19 patients with ABO-i living donors were analyzed within 90 days after RTx. Nineteen biopsy specimens with acute rejection after ABO-compatible (ABO-c) living-related RTx were used as controls. Diffuse and bright C4d deposition in PTC was considered significantly positive. RESULTS: All of 8 recipients with AHR showed significantly positive C4d in PTC in the ABO-i group, but 9 of 11 recipients without AHR were negative. In the ABO-c RTx group, 16 of 19 recipients were negative for C4d in PTC. The prevalence of C4d in PTC was significantly higher in ABO-i RTx (P<0.05). CONCLUSIONS: C4d deposition is valuable as a specific and sensitive indicator for AHR, even of mild severity, in ABO-i RTx.

ABO Blood-Group System↗
PubMed2003

Oral carbonaceous absorbent modifies renal function of renal ablation model without affecting plasma renin-angiotensin system or protein intake.

BACKGROUND: Although it has been repeatedly shown that the oral carbonaceous absorbent AST-120 ameliorates the progression of chronic renal failure, the mechanisms remain unknown. METHODS: Male Sprague-Dawley rats (6 weeks old), weighing 180-210 g, were 4/5 nephrectomized, and were divided into two groups: one given AST-120 (0.4 g/100 g body weight BW; n= 9) and the other not given AST-120 ( n = 9). Body weight, blood pressure, and serum and urine chemistry, as well as the plasma components of the renin-angiotensin system, were measured for 22 weeks. RESULTS: Proteinuria was significantly greater in the controls than in the AST-120 group (102 +/- 22 vs 51 +/- 7 mg/day at 22 weeks). Urea clearance was lower in the former (3.7 +/- 0.4 vs 3.9 +/- 0.4 ml/min). There were no differences in plasma renin activity (1.4 +/- 0.3 vs 1.9 +/- 0.4 mg/ml per h), or in angiotensin I (756 +/- 119 vs 1042 +/- 168 pg/ml) and II (35.1 +/- 7.4 vs 46.6 +/- 7.6 pg/ml) or angiotensin-converting enzyme activity (39.0 +/- 2.4 vs 37.9 +/- 2.2 IU/l) between the two groups. Protein intake, estimated from urinary urea appearance, was not different. Serum phosphate concentration (6.6 +/- 0.3 vs 5.9 +/- 0.3 mg/dl) was higher in the control than in AST-120, while the urinary phosphate excretion rate (31.5 +/- 0.8 vs 28.1 +/- 1.8 mg/day) tended to be lower in the latter. Conclusions. AST-120 retarded the progression of renal failure in the 4/5 renal ablation model without affecting the plasma renin-angiotensin system or protein intake, both of which were the most important risk factors for the progression of renal failure. We hypothesize that the renal protective effects of the oral absorbent AST-120 may be, at least in part, due to its lowering phosphate absorption from the diet as a phosphorus binder.

Adsorption↗
PubMed2003

A double staining flow cytometric assay for the detection of steroid induced apoptotic leucocytes in common carp (Cyprinus carpio).

Steroid hormones play an important role in the regulation of the immune system through different ways. In this in vitro study, the effects of steroid hormones on the apoptosis of leucocytes were evaluated to understand the involvement of this process in the immunocompetence of common carp. Prior to the investigation, a double staining flow cytometric assay using fluorescein diacetate (FDA), which reacts with esterases of viable cells, and propidium iodide (PI), an acid dye that binds with nuclear DNA, was established. FDA and PI negative cells were regarded as apoptotic. The FDA-PI technique is comparable to the Annexin V-PI technique and can be used in the quantification of the apoptosis of fish leucocytes accurately. The results suggest that the disappearance of esterases and externalization of phosphatidylserine (PS) may be common to many apoptotic pathways. Cells collected from peripheral blood, spleen, head kidney, and thymus were cultured for 16 h either in the absence or presence of steroid hormones, i.e. cortisol (F), testosterone, 11-ketotestosterone, and estradiol-17beta, and analyzed by flow cytometry followed by the FDA-PI method. Results showed that F induced apoptosis in leucocytes from blood and other lymphoid organs suggesting the role of F as an immune regulator. The participation of sex steroids to the immunocompetence of carp was not found, since they did not induce apoptosis of leucocytes in any organ.

Animals↗