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Yoshitaka Maeda

Publications and source records attributed to Yoshitaka Maeda.

15 recordsLinked to original sources
PubMed2007

Fulminant pneumatosis intestinalis in a patient with diabetes mellitus and minimal change nephrotic syndrome.

We report a case of pneumatosis intestinalis in a diabetic patient with minimal change nephrotic syndrome, receiving immunosuppressive drugs and an alpha-glucosidase inhibitor. The patient was a 72-year-old female, who suffered from right lower abdominal pain. Abdominal CT showed massive air in the intestinal wall, compatible with pneumatosis intestinalis. Her general condition rapidly deteriorated with systemic inflammatory response syndrome. The patient had received respiratory support for a week, along with antimicrobial therapy and continuous hemofiltration, and then recovered. Even though pneumatosis intestinalis is generally recognized as a mild disease, careful attention is necessary when it follows a serious condition.

Aged↗
PubMed2006

Trp53 affects the developmental anomaly of clefts of the palate in irradiated mouse embryos but not clefts of the lip with or without the palate.

Trp53-deficient mice exhibit increased incidences of developmental anomalies when irradiated, probably due to lack of Trp53-dependent apoptosis. A/J strain-derived CL/Fr mice develop clefts of the lip with or without the palate (CL/P) in approximately one-fifth of the embryos. We produced Trp53-deficient CL/Fr mice and examined the susceptibility to spontaneous development of CL/P and clefts of palate only (CPO), which differ in their developmental mechanisms, CL/P resulting from clefts of the primary palate and CPO from clefts of the secondary palate. The effect of radiation on the two phenotypes was also studied. Unexpectedly, no increase in the frequency of CL/P was observed under either condition, indicating that Trp53 deficiency does not contribute to genesis of CL/P. On the other hand, radiation enhanced the incidence of CPO in Trp53(+/+) embryos but not in Trp53(+/-) and Trp53(-/-/) embryos, suggesting that the absence or presence of only one allele of Trp53 is insufficient to hinder differentiation and proliferation of cells involved in the secondary palate formation. These results indicate that Trp53 function adversely affects the development of CPO when certain damaging agents such as radiation are given.

Animals↗
PubMed2005

Exact analysis of ESR shift in the spin-1/2 Heisenberg antiferromagnetic chain.

A systematic perturbation theory is developed for the ESR shift and is applied to the spin-1/2 Heisenberg antiferromagnetic chain with a general anisotropic exchange interaction. Using the Bethe ansatz technique, the resonance shift is obtained exactly for the whole range of temperature and magnetic field in the first order of the anisotropy. The obtained g shift strongly depends on magnetic fields at low temperature, showing a significant deviation from the previous classical result.

Journal Article↗
PubMed2005

[Flow cytometric analysis of mesothelial cells in peritoneal dialysis effluent].

According to recent reports, deformity and size of mesothelial cells reflect mesothelial condition. We applied flow cytometry (FCM) to the analyzation of mesothelial cells in peritoneal dialysis effluent (PDE) and the relationship between the period of peritoneal dialysis (PD) and peritoneal function. Eighteen patients treated for two to 89 months by PD were selected. Their dialysate: plasma creatinine ratio (D/P creatinine)was 0.67 +/- 0.086 (0.53 to 0.87). Overnight PDE was drained and centrifuged. The cell population of peritoneal cells identified by anti-cytokeratin, CD14 and 45 antibodies was studied by FCM. Cytokeratin positive cells were identified as mesothelial cells, distinct from macrophages, granulocytes or lymphocytes. The forward scatter (FSC) of cytokeratin positive cells, fluorescence intensity of cytokeratin and percentage of cytokeratin-positive cells in PDE were 395.6 +/- 55.5 (298.31 to 527.72), 333.9 +/- 272.9 (67.55 to 1,071.95), and 6.75 +/- 6.1% (0.44 to 21.14), respectively. There was a positive correlation between D/P creatinine and FSC, and a negative correlation between D/P creatinine and cytokeratin fluorescence intensity or the percentage of cytokeratin positive cells. However, there was no correlation between the period of PD and FSC, cytokeratin fluorescence intensity or the percentage of cytokeratin-positive cells. It was suggested that the alteration of mesothelial cells is not necessarily influenced by the period of PD, but influences peritoneal function. It was found that the analysis of cell population by FCM reflects the morphological and functional changes in the peritoneum of patients on PD.

Adult↗
PubMed2005

[Estimation of glomerular filtration rate by inulin clearance: comparison with creatinine clearance].

Inulin clearance (Cin) is widely believed to be the gold standard of the glomerular filtration rate (GFR). However, in Japan, Cin has not been officially recognized by the Ministry of Health, Labour and Welfare of Japan for clinical use. Creatinine clearance (Ccr) has been used to estimate the renal function of patients, but there have been many studies in which Ccr estimates were GFR falsely high because the metabolism and tubular excretion of creatinine widely varied according to the pathophysiological state of the patient. In the present study, we determined Cin and Ccr simultaneously in 116 adult patients with renal diseases and diabetic mellitus. The clearance study was performed by the modified Wesson's method. The inulin preparation was FFI-1010 (Fuji Yakuhin Co. Ltd.). Inulin in serum and urine was determined by the newly devised enzymatic assay (Toyobo Co. Ltd.), which is specific for inulin. The mean Cin was 35.0 +/- 14.4 ml/min/1.73 m2. The mean Ccr(the enzyme assay) was 63.6 +/- 24.1 ml/min/1.73 m2 and that of the kinetic Jaffe assay was 55.3 +/- 19.3 ml/min/1.73 m2. Mean Ccr/Cin was 1.93 +/- 0.73, 1.69 +/- 0.62, respectively. This ratio was significantly different(p < 0.05) in the degree of reduction of Cin, with values of 2.07 +/- 0.82 (Cin < 40 ml/min/1.73 m2) and 1.64 +/- 0.32(40 < Cin < 80 ml/min/1.73 m2), respectively. Only 8 patients were classified into the same degree of reduced renal function (the Guideline of Japanese Society of Nephrology). The findings of this study suggest that the GFR determined by Ccr could misjudge the renal function of patient and delay the administration of proper treatment of the patient. Introduction of Cin into the clinical field is necessary to avoid this delay.

Acute Disease↗
PubMed2005

[Blood ionized calcium fraction in various serum albumin levels surveyed in non-dialysis patients].

Blood ionized calcium (iCa) fraction is affected by the serum albumin(Alb) level, even though this effect might not be appropriately estimated by the formulae proposed previously. To clarify a reasonable regimen for predicting iCa from serum total Ca (tCa), we investigated the relationship of blood iCa, tCa, and serum Alb levels through 124 samples from 116 non-dialysis patients requiring iCa measurement at the Nephrology Section of Toride Kyodo General Hospital. The patients comprised 61 males and 55 females with the mean age of 66.9 +/- 1.4 years, including 9 cases of hypercalcemia, 110 of normocalcemia, and 5 of hypocalcemia based on their iCa levels. Their background diseases were 25 cases of chronic glomerulonephritis, 17 of nephrotic syndrome, 40 of diabetes mellitus, 4 of collagen diseases, and 30 of others. Their mean serum Cr was 2.44 +/- 0.21 mg/dl, and 77 patients showed elevated Cr levels. Four adjustment formulae: one derived from Payne's, two from the proposal of K/DOQI Clinical Practice Guidelines, and a theoretical one based on the previous in vitro experiments, were compared with the non-adjusted value (tCa itself) with respect to their suitability for estimating iCa. The correlation coefficient of tCa with iCa was higher than the values adjusted by the above four formulae. The difference of iCa from tCa divided by eight, which concisely predicted iCa based on the assumption that half the serum Ca is bound to protein, was less than 1/8th of the other adjusted Ca levels. Hence none of the adjusted Ca by the above formulae was superior to nonadjusted tCa from the point of estimating the iCa level. Moreover, the sensitivity for predicting hypocalcemia was the highest in tCa, even though its specificity was lower than the other adjusted values. In conclusion, no adjustment formula is required to predict ionized Ca from tCa, and to screen hypo- or hypercalcemia.

Adolescent↗
PubMed2004

Oligopeptide-mediated acceleration of amyloid fibril formation of amyloid beta(Abeta) and alpha-synuclein fragment peptide (NAC).

The effects of oligopeptides on the secondary structures of Abeta and NAC, a fragment of alpha-synuclein protein, were studied by circular dichroism (CD) spectra. The effects of oligopeptides on the amyloid fibril formation were also studied by fluorescence spectra due to thioflavine-T. The oligopeptides were composed of a fragment of Abeta or NAC and were interposed by acidic or basic amino acid residues. The peptide, Ac-ELVFFAKK-NH2, which involved a fragment Leu-Val-Phe-Phe-Ala at Abeta(17-21), had no effect on the secondary structures of Abeta(1-28) in 60% or 90% trifluoroethanol (TFE) solutions at both pH 3.2 and pH 7.2. However, it showed pronounced effects on the secondary structure of Abeta(1-28) at pH 5.4. The Ac-ELVFFAKK-NH2 reduced the alpha-helical content, while it increased the beta-sheet content of Abeta(1-28). In phosphate buffer solutions at pH 7.0, Ac-ELVFFAKK-NH2 had little effect on the secondary structures of Abeta(1-28). However, it accelerated amyloid fibril formation when monitored by fluorescence spectra due to thioflavine-T. On the other hand, LPFFD, a peptide known as a beta-sheet breaker, caused neither an appreciable extent of change in the secondary structure nor amyloid fibril formation in the same buffer solution. The peptide, Ac-ETVK-NH2, which involved a fragment Thr-Val at NAC(21-22), had no effect on the secondary structure of NAC in 90% TFE and in isotonic phosphate buffer. However, Ac-ETVK-NH2 in water with small amounts of NaN3 and hexafluoroisopropanol greatly increased the beta-sheet content of NAC after standing the solution for more than 1 week. Interestingly, in this solution. Ac-ETVK-NH2, accelerated the fibril formation of NAC. It was concluded that an oligopeptide that involves a fragment of amyloidogenic proteins could be a trigger for the formation of amyloid plaques of the proteins even when it had little effect on the secondary structures of the proteins as monitored by CD spectra for a short incubation time.

Amino Acid Sequence↗
PubMed2004

[Dilution index as a candidate parameter reflecting dialysis dose in combined peritoneal dialysis and hemodialysis therapy].

Combined peritoneal dialysis and hemodialysis therapy (combined therapy) is recognized as an effective alternate in peritoneal dialysis patients with insufficient water and solute removal, but there is no appropriate index for dialysis dose, as two distinct dialysis procedures are utilized in the same patient. Among several candidate parameters, the dilution index proposed and defined by Yamada, et al as the solute generation rate divided by the distribution volume and time-averaged concentration of the solute might be applicable, because it is unrelated to the method of solute removal. Among 11 patients undergoing combined therapy at Toride Kyodo General Hospital, six patients who had transferred from peritoneal dialysis alone to combined therapy were recruited. All patients received peritoneal dialysis therapy for five consecutive days followed by one day off dialysis before a hemodialysis session on the seventh day every week. Total weekly creatinine and urea removal by residual renal function, peritoneal dialysis, and hemodialysis were measured, and their solute removal on the last(5th) day under peritoneal dialysis was ascertained and correlated with the averaged daily removal of solutes. Hence the value of solute removal obtained on the last day under peritoneal dialysis was multiplied seven times and defined as the weekly solute generation. The distribution volumes of creatinine and urea were defined as 58% of body weight. The time-averaged concentration was obtained from the mean level of a solute before and after a hemodialysis session. During the period followed solely by peritoneal dialysis, the dilution indices for creatinine and urea were 1.22 +/- 0.14 and 1.85 +/- 0.14, respectively. The dilution index after transferring to combined therapy, calculated by the above-mentioned method was increased to 1.72 +/- 0.29 and 2.28 +/- 0.31, respectively. Hence the dilution index may be useful for reflecting dialysis doses even in combined therapy.

Combined Modality Therapy↗
PubMed2003

Oligonucleotide microarray for prediction of early intrahepatic recurrence of hepatocellular carcinoma after curative resection.

BACKGROUND: Hepatocellular carcinoma has a poor prognosis because of the high intrahepatic recurrence rate. There are technological limitations to traditional methods such as TNM staging for accurate prediction of recurrence, suggesting that new techniques are needed. METHODS: We investigated mRNA expression profiles in tissue specimens from a training set, comprising 33 patients with hepatocellular carcinoma, with high-density oligonucleotide microarrays representing about 6000 genes. We used this training set in a supervised learning manner to construct a predictive system, consisting of 12 genes, with the Fisher linear classifier. We then compared the predictive performance of our system with that of a predictive system with a support vector machine (SVM-based system) on a blinded set of samples from 27 newly enrolled patients. FINDINGS: Early intrahepatic recurrence within 1 year after curative surgery occurred in 12 (36%) and eight (30%) patients in the training and blinded sets, respectively. Our system correctly predicted early intrahepatic recurrence or non-recurrence in 25 (93%) of 27 samples in the blinded set and had a positive predictive value of 88% and a negative predictive value of 95%. By contrast, the SVM-based system predicted early intrahepatic recurrence or non-recurrence correctly in only 16 (60%) individuals in the blinded set, and the result yielded a positive predictive value of only 38% and a negative predictive value of 79%. INTERPRETATION: Our system predicted early intrahepatic recurrence or non-recurrence for patients with hepatocellular carcinoma much more accurately than the SVM-based system, suggesting that our system could serve as a new method for characterising the metastatic potential of hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed2003

Oligopeptide-mediated helix stabilization of model peptides in aqueous solution.

Oligopeptide-mediated helix stabilization of peptides in hydrophobic solutions was previously found by NMR and CD spectroscopic studies. The oligopeptide included the hydrophobic amino acids found in its parent peptide and were interposed by relevant basic oracidic amino acids. The strength of the interactions depended on the amino acid sequences. However, no helix-stabilizing effect was seen for the peptides in phosphate buffer solution, because the peptides assumed a random-coil structure. In order to ascertain whether the helix-stabilizing effect of an oligopeptide on its parent peptide could operate in aqueous solution, model peptides EK17 (Ac-AEAAAAEAAAKAAAAKA-NH2) and IFM17 (Ac-AEAAAAEIFMKAAAAKA-NH2) that may assume an alpha-helix in aqueous solutions were synthesized. Interactions were examined between various oligopeptides (EAAAK, KAAAE, EIFMK, KIFME, KIFMK and EYYEE) and EK17 or IFM17 in phosphate buffer and in 80% trifluoroethanol (TFE)-20% H2O solutions by CD spectra. EAAAK had little effect on the secondary structures of EK17 in both buffer and TFE solutions, while KAAAE, which has the reverse amino acid sequence of EAAAK, had a marked helix-destabilizing effect on EK17 in TFE. EIFMK and KIFME were found to stabilize the alpha-helical structure of EK17 in phosphate buffer solutions, whereas KIFMK and EYYEE destabilized the alpha-helical structure of EK17. EIFMK and KIFME had no effect on IFM17, because unexpectedly, IFM17 had appreciable amounts of beta-sheet structure in buffer solution. It was concluded that in order for the helix-stabilizing (1) the model peptide, the alpha-helical conformation of which is to be stabilized, should essentially assume an alpha-helical structure by nature, and (2) the hydrophobicity of the side-chains of the oligopeptide should be high enough for the oligopeptide to perform stable specific side chain-side chain intermolecular hydrophobic interactions with the model peptide.

Circular Dichroism↗
PubMed2003

Effects of detergents on the secondary structures of prion protein peptides as studied by CD spectroscopy.

Pathogenic prion proteins (PrP(Sc)) are thought to be produced by alpha-helical to beta-sheet conformational changes in the normal cellular prion proteins (PrP(C)) located solely in the caveolar compartments. In order to inquire into the possible conformational changes due to the influences of hydrophobic environments within caveolae, the secondary structures of prion protein peptides were studied in various kinds of detergents by CD spectra. The peptides studied were PrP(129-154) and PrP(192-213); the former is supposed to assume beta-sheets and the latter alpha-helices, in PrP(Sc). The secondary structure analyses for the CD spectra revealed that in buffer solutions, both PrP(129-154) and PrP(192-213) mainly adopted random-coils (approximately 60%), followed by beta-sheets (30%-40%). PrP(129-154) showed no changes in the secondary structures even in various kinds of detergents such as octyl-beta-D-glucopyranoside (OG), octy-beta-D-maltopyranoside (OM). sodium dodecyl sulfate (SDS), Zwittergent 3-14 (ZW) and dodecylphosphocholine (DPC). In contrast, PrP(192-213) changed its secondary structure depending on the concentration of the detergents. SDS, ZW, OG and OM increased the alpha-helical content, and decreased the beta-sheet and random-coil contents. DPC also increased the alpha-helical content, but to a lesser extent than did SDS, ZW, OG or OM. These results indicate that PrP(129-154) has a propensity to adopt predominantly beta-sheets. On the other hand, PrP(192-213) has a rather fickle propensity and varies its secondary structure depending on the environmental conditions. It is considered that the hydrophobic environments provided by these detergents may mimic those provided by gangliosides in caveolae, the head groups of which consist of oligosaccharide chains containing sialic acids. It is concluded that PrP(C) could be converted into a nascent PrP(Sc) having a transient PrP(Sc) like structureunder the hydrophobic environments produced by gangliosides.

Animals↗
PubMed2003

Newly established low seizure susceptible and seizure-prone inbred strains of Mongolian gerbil.

Two inbred strains of the Mongolian gerbil with different phenotypes in seizure behaviour and coat color were newly established. LSAG/Nu has low seizure susceptibility and albino phenotypes, whereas SPBG/Nu has seizure-prone and black coat color phenotypes. LSAG was compared with SPBG as to seizure incidence and grade. Mean ages at seizure onset of LSAG and SPBG were 6 and 3 months, respectively. Seizure incidences in over 9 months old LSAG and SPBG gerbils were 37.3% (66/177) and 95.2% (118/124), respectively. LSAG has a significantly lower incidence (p < 0.001) and grade (p < 0.001) of seizures than SPBG. Only a few seizing LSAG gerbils exhibited myoclonus to tonic-clonic seizure progression. These results suggest that LSAG has some mechanisms which delay the onset of seizures and prevent them from becoming serious. Both strains of gerbils can be expected to be useful animal models for the study of human idiopathic generalized epilepsy.

Animals↗
PubMed2003

[Protein restriction diet in the predialysis period does not decrease survival of uremic patients after the introduction of hemodialysis therapy].

To clarify whether a protein restriction diet in the pre-dialysis period affects the overall prognosis after initiating hemodialysis therapy, we compared the survival between patients with and without a protein restriction diet. Among 310 patients in whom hemodialysis was introduced between 1997 and 2000 at Toride Kyodo General Hospital, two hundred and ten patients were excluded due to an insufficient observation period (< 6 months) or the lack of records estimating their protein intake. One hundred patients were finally included in this study. All of these patients were followed at the hospital with their estimated protein intake using repeated (three times or more) urea nitrogen appearance in 24-hour collected urine samples over 6 months period to the initiation of dialysis therapy. The patients were divided into a protein restriction diet group (PRD 61 cases) and non-restriction diet group (NRD 39 cases), according to their estimated protein intake less or above 0.7 g/kg/day. Among the patient profile items, gender, cause of renal failure, and serum albumin did not differ between the two groups, but the age was higher in NRD (p < 0.01). Nineteen patients (PRD 8, NRD 11 cases) died during the observation period (0-65 months). On the analysis of their survival, PRD showed a better survival ratio by the Kaplan-Meier method (p < 0.01). Among the variables examined by Cox's proportional hazard test, age, PRD, and their combination showed significant risk ratios (1.06, 0.30, and 0.39 respectively) on survival after the initiation of hemodialysis. Hence a protein restriction diet in the pre-dialysis period does not deteriorate the prognosis even after the initiation of hemodialysis therapy.

Aged↗
PubMedDate not supplied

Risk factors for postoperative liver failure after hepatectomy for hepatocellular carcinoma.

BACKGROUND/AIMS: Selection of patients for hepatectomy for hepatocellular carcinoma conventionally has been based upon Child-Pugh grading. However, postoperative liver failure after hepatectomy is a major cause of hospital mortality. A new predictor of postoperative liver failure is required. The objective of this study was to identify risk factors for postoperative liver failure after hepatectomy. METHODOLOGY: Perioperative risk factors for liver failure after hepatectomy were analyzed in 112 patients with hepatocellular carcinoma Eight of these patients died of liver failure. Stepwise multivariate logistic regression was performed to investigate significant independent factors among 17 variables, including the serum alkaline phosphatase ratio (ALPR) on the first day after hepatectomy. ALPR was calculated as the postoperative ALP level divided by the ALP level before surgery. RESULTS: Significant risk factors of postoperative liver failure were ALPR on postoperative day 1 (ALPR1), sex, operative blood loss, and operative procedure. As an indicator of liver failure, the diagnostic accuracy of the ALPR1 was 93.7% when the ALPR was less than 0.4 on the first postoperative day. The ALPR and the serum total bilirubin concentration after hepatectomy were uncorrelated. CONCLUSIONS: ALPR1 is a useful predictor of liver failure after hepatectomy.

Aged↗