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Biomedical subjects

K Hamada

Publications and source records attributed to K Hamada.

At least 181 records · Page 10Linked to original sources
PubMed1998

Shortening of monophasic action potential duration during hyperkalemia and myocardial ischemia in anesthetized dogs.

The elevation of the myocardial extracellular potassium concentration ([K+]o) is known to shorten action potential duration, which may lead to the occurrence of arrhythmias. The aim of this study was to compare the mechanisms responsible for the shortening of monophasic action potential duration (MAPD) in hyperkalemic and myocardial ischemic hearts in anesthetized dogs. During a venous infusion of KCl for 5 min, [K+]o was increased and MAPD was significantly shortened. The ATP-sensitive K+ (K[ATP]) channel blocker glibenclamide did not affect the shortening of MAPD during KCl-infusion, indicating that K(ATP) channels are not involved in this mechanism. During 5-min occlusion of the left anterior descending coronary artery, [K+]o was increased, myocardial pH was decreased and MAPD was shortened. Glibenclamide completely abolished the shortening of MAPD, while partial elevation of [K+]o remained even in the presence of glibenclamide. This suggests that the shortening of MAPD is dependent mainly on the activation of K(ATP) channels. Both models in the present study demonstrate that different types of potassium channels are involved in the regulation of action potential duration.

Action Potentials↗
PubMed1998

Crossroads of the effects of cyclophosphamide pulse therapy for lupus nephritis--experience of 11 cases.

In this study time for initial assessment of monthly intravenous cyclophosphamide (CP) pulse therapy is discussed for a better outcome with less complications. Eleven patients with lupus nephritis (LN) resistant to conventional therapy (serum creatinine level < or = 2.7 mg/dl) were given 500 mg/m2 of CP 7-9 times with an interval of one month. Urinary protein (Up) decreased in all patients after 3 courses of CP pulse therapy and kept similar levels thereafter. In one group of patients (n = 7), Up decreased to < 2 g/day after 3 courses, while in the other group (n = 4), it did not decrease to < 4 g/day. Creatinine clearance increased by 0-100% in the former group, while it decreased by 5-20% in the latter group after 6-9 courses. Renal function of the patients with insufficient response after 3 courses tended to show no further improvement or worsened thereafter, although Up decreased during CP pulse therapy. A relatively small dose of CP (500 mg/m2) pulse therapy was useful in most LN patients regardless of the renal histology and it was thought important to assess its effects after 3 courses for a prediction of the clinical course. Modification of the protocol at that time might be necessary in regard to dose or interval of CP administration especially for patients with insufficient outcome.

Adult↗
PubMed1998

Usefulness of the medaka beta-actin promoter investigated using a mutant GFP reporter gene in transgenic medaka (Oryzias latipes).

The activity of the medaka beta-actin promoter as a ubiquitous expression vector in transgenic medaka was examined using complementary DNA of the green fluorescent protein (GFP). Plasmid pOBA-GFP contained both the medaka beta-actin promoter and cDNA of the wild-type GFP, while pOBA-hGFP contained the medaka beta-actin promoter and cDNA of the mutant GFP in which serine was substituted for threonine at position 65 and codon usage was humanized to promote translation in vertebrate cells. The ApaI-SmaI fragment of both plasmids was microinjected into the nuclei of oocytes or the cytoplasm of embryos at the one-cell stage. The gene expression was detected, using a fluorescent stereomicroscope, from early stages of development to 1 week after hatching. The expression of the wild-type GFP was detected in early embryos, in the yolk sac and in small portions of the muscle and epidermis. This expression pattern was similar to that of the Escherichia coli beta-galactosidase reporter gene (lacZ), driven by the medaka beta-actin promoter, which was examined in our previous studies. The mutant GFP was expressed in early embryos and in many tissues such as the epidermis, blood vessels, muscle, notochord, fin ray, gut, eyes, and yolk sac, and the fluorescence was much stronger than that of the wild-type GFP. Thus, the usefulness of the medaka beta-actin promoter as a ubiquitous expression vector was confirmed using the mutant GFP as a reporter gene.

Actins↗
PubMed1998

[Small cell lung cancer associated with nephrotic syndrome: remission after chemotherapy].

A 66 year-old man was found to have pointed out a 1-cm tumor shadow, on a chest X-ray film when he underwent a gastrectomy because of advanced gastric cancer. Five months after the operation, edema and proteinuria developed, and a chest X-ray film revealed enlargement of the tumor. There was no sign of recurrence of the gastric cancer. Nephrotic syndrome due to IgA-nephropathy and small cell lung cancer was diagnosed. Chemotherapy (carboplatin and etoposide) was effective against both the lung tumor and the nephrotic syndrome. Small cell lung cancer may have been involved in the pathogenesis of the nephrotic syndrome in this patient.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

[Apoptosis of peripheral leukocytes in patients with myelodysplastic syndromes].

Apoptosis of peripheral leukocytes in 9 patients with myelodysplastic syndromes (MDS) was examined in vitro, using peripheral blood that had been gently incubated at 37 degrees C for 5 hours. The MDS patients included 3 with refractory anemia, 2 with refractory anemia with ringed sideroblasts, and 4 with refractory anemia with excess blasts. Peripheral blood specimens were also obtained from a control group consisting of 10 patients with iron deficiency anemia (IDA), 10 with idiopathic thrombocytopenic purpura (ITP) and 10 healthy individuals. Apoptotic granulocytes (Apo-Gs) were identified by morphological changes, including nuclear fragmentation, and expressed as a percentage of every 300 granulocytes counted. Apo-Gs were counted 1, 2, 3, 4, and 5 hours after incubation. Although the percentage of apo-Gs climbed over time in the MDS patients, a small number of apo-Gs were also observed in the healthy individuals. In the MDS patients, the proportions of apo-Gs 5 hours after incubation (37 degrees C) were significantly higher than those in the IDA and ITP patients and healthy individuals (15.7 +/- 8.0% in MDS patients vs. 2.8 +/- 1.2% in IDA patients, 2.3 +/- 1.7% in ITP patients, and 0.7 +/- 0.6% in healthy individuals; p < 0.005). No significant differences were observed in the proportions of apo-lymphocytes. DNA fragments were observed in blood lymphocyte from an MDS patient examined. Negative correlations between the percentages of granulocytes and Apo-Gs tended to be observed in the MDS patients. These results suggest that a strong susceptibility to peripheral granulocyte apoptosis is one of possible causes of granulocytopenia in MDS patients.

Agranulocytosis↗
PubMed1998

[Effect of clarithromycin treatment of natural killer cell activity in patients with advanced non-small cell lung cancer].

The treatment of a 14-membered ring macrolide, clarithromycin (CAM), prolongs the survival time of patients with unresectable nonsmall cell lung cancer, and improves the host factor. As we previously reported, one of the underlying mechanisms is that the treatment of CAM increases the bioactivity of interleukin-12 (IL-12). In the present study, we administered CAM to murine lung cancer treatment models with Lewis lung carcinoma and to 18 patients with unresectable non-small lung cancer whose anticancer treatment had been terminated. The timing of CAM administration was examined and the time course of NK activity was measured. In the murine lung cancer treatment models, administration of CAM 7 days after anticancer chemotherapy more strongly inhibited the tumor growth and more rapidly and significantly increased NK activity, compared to the concomitant use of CAM with an anticancer chemotherapy. In humans, the NK activity which had decreased after anticancer treatment, tended to be increased after one month of treatment with CAM (p = 0.06). One month of treatment with CAM significantly increased the NK activity (p < 0.05) of the following subjects: patients with stage III in the clinical stages, patients with squamous cell carcinoma, patients who had received radiotherapy alone as pretreatment therapy, and patients whose pretreatment therapy effect was partial response (PR). We conjectured that increasing NK activity was one of the underlying mechanisms of the macrobiotic effect of CAM. CAM was especially effective for patients in the early clinical stages and patients who responded well to pretreatment therapy. Murine lung cancer models showed that non-concomitant use of CAM with anticancer chemotherapy was more effective.

Aged↗
PubMed1998

[Renal hemodynamic interactions of nitric oxide and angiotensin II].

We have already reported that decreased renal medullary blood flow and retention of sodium play an important role in the development of hypertension during chronic systemic L-NAME (NG-nitro-L-arginine methyl ester) administration, despite the absence of measurable changes in renal cortical blood flow as determined from fibers implanted for laser-Doppler flowmetry. In the present experiment, to investigate the interaction between nitric oxide and angiotensin II on renal hemodynamics, the effect of chronic intravenous infusion of L-NAME on blood pressure, sodium and water retention, and intrarenal blood flow distribution were studied in a separate group of rats pretreated with captopril and in which optical fiber for laser-Doppler flowmetry had been implanted. Captopril completely prevented sustained hypertension, sodium retention, and decreased medullary blood flow during chronic L-NAME infusion. These date indicated that angiotensin plays an important role in the regulation of renal medullary blood flow and sodium excretion by modulating the effects of nitric oxide in renal medullary blood flow.

Angiotensin II↗
PubMed1998

[A case of malignant rheumatoid arthritis complicated by secondary amyloidosis and membranous nephropathy].

A 30-year-old man had been treated for malignant rheumatoid arthritis from 1989 with a non-steroidal anti-inflammatory drug, then bucillamine for six months and prednisolone. Mild proteinuria appeared in May 1994, 4 years after bucillamine therapy was conducted. The patient was admitted to our hospital for a renal biopsy in July 1994. The specimen revealed secondary amyloidosis and membranous nephropathy (MGN). These findings suggest that MGN unrelated to bucillamine therapy might have occurred with secondary amyloidosis in rheumatoid arthritis.

Adult↗
PubMed1997

Identification of NAP-22 and GAP-43 (neuromodulin) as major protein components in a Triton insoluble low density fraction of rat brain.

NAP-22 is a membrane-localized brain enriched acidic protein having a Ca(2+)-dependent calmodulin binding activity. Further fractionation of the NAP-22 containing membrane showed the localization of NAP-22 in a Triton insoluble fraction of low density. Besides NAP-22, this fraction was found to contain GAP-43 (neuromodulin), trimeric G proteins, and some GPI-anchored proteins such as Thy-1 and N-CAM-120. Presence of some protein tyrosine kinases, such as src and fyn, was also shown.

Amino Acid Sequence↗
PubMed1997

Crystallization and preliminary X-ray studies of plastocyanin from Silene expressed in E. coli.

Plastocyanin from Silene (SilPc) expressed in E. coli has been crystallized in a form suitable for X-ray diffraction analysis by a macroseeding method using ammonium sulfate as a precipitant in acetate buffer (pH = 5.5). These crystals belong to the trigonal space group P3(1)21 or P3(2)21 with lattice parameters a = b = 76.6, c = 65.5 A, indicating an asymmetric unit containing two plastocyanin molecules. The crystals diffracted to at least 2.0 A.

Journal Article↗
PubMed1997

Intrinsic healing capacity and tearing process of torn supraspinatus tendons: in situ hybridization study of alpha 1 (I) procollagen mRNA.

To determine the healing potential and healing process of torn supraspinatus tendons, in situ hybridization was used to localize cells containing alpha 1 type-I procollagen mRNA. Biopsy specimens of torn supraspinatus tendons from 19 patients with complete-thickness tears and 13 patients with incomplete-thickness tears were obtained during surgery. Four macroscopically normal supraspinatus tendons were obtained to serve as normal controls. Specimens were fixed in 10% buffered formalin and embedded in paraffin. A 22-mer oligonucleotide probe was labeled with digoxigenin and used as an in situ marker. The labeled cells were mainly composed of tenocytes and undifferentiated mesenchymal cells. In complete-thickness-tears, the labeled cells at the proximal tendon-stumps in the specimens that were obtained less than 4 months after trauma were significantly more abundant than in the specimens obtained 4 months or more after trauma. However, the number of labeled cells was maintained at the torn portion even in long-standing incomplete-thickness tears. The labeled cells at the margins of concomitant intratendinous extensions of the tears were detected even in the long-standing tears. The intratendinous extensions exhibited more labeled cells than the bursal-side or joint-side layers of the tendon substance in the incomplete-thickness tears (p < 0.05). The torn supraspinatus tendon may possess an intrinsic healing capability in the intermediate and late phases of tendon healing. Incomplete-thickness tears and concomitant intratendinous extensions can continue to rupture after the initial injury.

Adult↗
PubMed1997

Significance of granulation tissue in torn supraspinatus insertions: an immunohistochemical study with antibodies against interleukin-1 beta, cathepsin D, and matrix metalloprotease-1.

The pathophysiology of rotator cuff tears can be elucidated by examining the tendinous insertion of the supraspinatus muscle. As seen by light microscopy, the granulation tissue around the insertion of a torn supraspinatus tendon appears to induce osteochondral destruction by means of multinucleated giant cells and chemical mediators. The purpose of this study was to examine the contribution of certain chemical mediators to osteochondral destruction using immunohistochemical analysis of interleukin-beta, cathepsin D, and matrix metalloprotease-1. Sixteen supraspinatus insertions with portions of the greater tuberosity, including eight complete-thickness tears and eight incomplete-thickness tears, were obtained during surgery. Six fresh cadaveric supraspinatus tendons without grossly evident tears served as normal controls. Strong immunoreactivity was found in all 16 torn supraspinatus insertions but not in the six insertions of apparently intact tendons. Macrophages and multinucleated giant cells, which showed immunoreactivity for all three chemical mediators, were often found at the interface between the osteochondral margin of the enthesis and the granulation tissue, suggesting that they may be involved in osteochondral destruction. We therefore concluded that, in addition to repetitive subacromial impingement, this granulation tissue may contribute to the development of rotator cuff tears by weakening the insertion.

Adult↗
PubMed1997

Structural analysis of a Candida glabrata centromere and its functional homology to the Saccharomyces cerevisiae centromere.

A 451-bp fragment exhibiting centromere activity had been previously isolated from Candida glabrata genomic DNA. It contains three elements, CgCDEI, CgCDEII and CgCDEIII, highly homologous to those of Saccharomyces cerevisiae. In this study, the requirement of each element for centromere function was analyzed in detail. Deletion analysis identified a small fragment of 153 bp, which included all three elements, to be sufficient for centromere activity. Linker substitution analysis of CgCDEI and CgCDEIII revealed that both elements are required for centromere function. Some of the substitution mutations in CgCDEIII caused a complete loss of centromere activity. These results suggested a functional similarity of centromeres between C. glabrata and S. cerevisiae. However, the C. glabrata centromere did not function in S. cerevisiae cells, suggesting species specificity of the C. glabrata centromere. To examine whether species specificity of the centromeres between these two yeasts does exist, chimeric centromeres between the two species were constructed. Exchange of CgCDEII or CgCDEIII with CDEII or CDEIII of S. cerevisiae, respectively, increased C. glabrata centromere activity in S. cerevisiae, indicating participation of the two elements in determining the species specificity of centromere function.

Base Sequence↗
PubMed1997

Dominantly inherited leukodystrophy showing cerebellar deficits and spastic paraparesis: a new entity?

We studied a dominant hereditary disorder showing progressive spastic paraparesis. The symptoms began in early childhood, with cerebellar deficits and mild mental deterioration, and the subsequent appearance of limb spasticity resulted in severe disability in the 3rd-4th decades of life. None of the patients were associated with any somatic abnormalities. Brain MRI showed diffuse white-matter involvement in all affected patients, but not in unaffected siblings. Although dominant, recessive, or X-linked leukodystrophies cause similar clinical features, our family did not show any known biochemical or gene deficits characteristic of these disorders. The clinical, radiological, and biochemical findings of this family are reported and suggest a possible novel genetic disorder.

Adult↗