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K Wakasugi

Publications and source records attributed to K Wakasugi.

At least 19 recordsLinked to original sources
PubMed1998

Genetic code in evolution: switching species-specific aminoacylation with a peptide transplant.

The genetic code is established in aminoacylation reactions whereby amino acids are joined to tRNAs bearing the anticodons of the genetic code. Paradoxically, while the code is universal there are many examples of species-specific aminoacylations, where a tRNA from one taxonomic domain cannot be acylated by a synthetase from another. Here we consider an example where a human, but not a bacterial, tRNA synthetase charges its cognate eukaryotic tRNA and where the bacterial, but not the human, enzyme charges the cognate bacterial tRNA. While the bacterial enzyme has less than 10% sequence identity with the human enzyme, transplantation of a 39 amino acid peptide from the human into the bacterial enzyme enabled the latter to charge its eukaryotic tRNA counterpart in vitro and in vivo. Conversely, substitution of the corresponding peptide of the bacterial enzyme for that of the human enabled the human enzyme to charge bacterial tRNA. This peptide element discriminates a base pair difference in the respective tRNA acceptor stems. Thus, functionally important co-adaptations of a synthetase to its tRNA act as small modular units that can be moved across taxonomic domains and thereby preserve the universality of the code.

Amino Acyl-tRNA Synthetases↗
PubMed1997

Structural and functional roles of modules in hemoglobin. Substitution of module M4 in hemoglobin subunits.

The alpha- and beta-subunits of human hemoglobin consist of the modules M1, M2 + M3, and M4, which correspond to the exons 1, 2, and 3, respectively (Go, M. (1981) Nature 291, 90-92). To gain further insight into functional and structural significance of the modules, we designed two kinds of chimeric hemoglobin subunits (chimeric alphaalphabeta- and betabetaalpha-subunits), in which the module M4 was replaced by the partner subunits. CD spectra in the far-UV region showed that the secondary structure of the chimeric alphaalphabeta-subunit drastically collapsed, while the chimeric betabetaalpha-subunit conserved the native globin structure (Wakasugi, K., Ishimori, K., Imai, K., Wada, Y., and Morishima, I. (1994) J. Biol. Chem. 269, 18750-18756). SAXS data also suggested a partially disordered structure of the chimeric alphaalphabeta-subunit. Based on tryptophan fluorescence spectra and computer modeling from x-ray structures of native globins, steric constraint between Trp14 and Tyr125 would be induced in the chimeric alphaalphabeta-subunit, which would perturb the packing of the A- and H-helices and destabilize the globule structure. On the other hand, such a steric constraint was not found for the counterpart chimeric subunit, the betabetaalpha-subunit. The different stabilities of these module-substituted globins imply that modules would not always be stable "structural" units, and interactions between modules are crucial to construct stable globin subunits.

Circular Dichroism↗
PubMed1997

'Module'-substituted globins: artificial exon shuffling among myoglobin, hemoglobin alpha- and beta-subunits.

Based on the detailed structural analysis of proteins, Go [M. Go, Nature 291 (1981) 90-92] found that protein structures can be divided into some structural units, 'modules,' which correspond to peptides coded by exons. In the present study, to investigate functional and structural roles of modular structures in proteins, we have engineered eight chimera globins, in which the exons are shuffled among human myoglobin, human hemoglobin alpha- and beta-subunits, in addition to the chimera beta beta alpha-globin described previously [K. Wakasugi, K. Ishimori, K. Imai, Y. Wada, I. Morishima, J. Biol. Chem. 269 (1994) 18750-18756]. Although all of the chimera globins stoichiometrically bound the heme and their alpha-helical contents increased by heme incorporation as found for native globins, the alpha-helical contents of the chimera globins were significantly lower than those of native globins, suggesting that 'module' substitutions seriously affect the protein folding and stability in globins. The comparisons among several chimera globins demonstrated that such structural alterations are mainly attributed to loss of some key intermodular interactions for protein folding. By simultaneous substitution of the modules M1 and M4 from the same globin, the protein structure was stabilized, which indicates that the module packing between modules M1 and M4 would be one of the crucial interaction to stabilize the globin fold. Present results allow us to conclude that module substitutions would be available for designing and producing novel functional proteins if we can reproduce the stable modular packing in the 'module'-substituted proteins.

Chromatography, Gel↗
PubMed1996

Trisomy 10 in acute myeloid leukemia.

We observed two patients with acute myeloid leukemia (AML) exhibiting trisomy 10 as the sole chromosome abnormality at the time of diagnosis. One patient was diagnosed with AML-MO, and the other with AML-M2. Both cases were CD7-antigen positive. However, we could not find any distinct clinico-hematologic characteristics of AML with trisomy 10 in these two patients. Trisomy 10 might be a rare recurring numerical chromosome abnormality and the incidence may be about 0.5% in de novo AML.

Aged↗
PubMed1996

NMR studies of recombinant cytochrome P450cam mutants.

In the active center of cytochrome P450cam, Thr-252 is one of the conserved amino acid residues in the cytochrome P450 superfamily and plays a key role in the hydroxylation of camphor. T252A mutant, in which Thr-252 is replaced by alanine, consumed O2 at a rate comparable to that of the wild-type enzyme, whereas the amount of exo-5-hydroxycamphor formed was less than 10% of that formed by the wild-typed enzyme and H2O2 is the main product in the hydroxylation reaction. H2O2 was also yielded by the valine mutant and the consumption rate of O2 was much lower than that for the wild-type enzyme (Imai et al (1989) Proc Natl Acad Sci USA 86, 7823-7827). On the basis of the 1H- and 15N-NMR spectra, it was revealed that the anionic nature of the axial thiolate and the heme-environmental structures were substantially affected in the absence of d-camphor by the amino acid substitution at 252 Thr. In T252A mutant, however, the binding of camphor reduced these conformational alterations in the heme vicinity, probably due to the formation of interactions between camphor and enzyme. On the other hand, T252V mutant still exhibited large reduction of the anionic nature of the axial ligand in the presence of d-camphor and structural changes around heme were also enhanced, since the affinity of the valine mutant to d-camphor was low. These results imply that the hydrophobic and/or steric effects of the valine residue at 252 interfere with interactions around heme and camphor binding sites, which corresponds to the larger functional defects for T252V mutant.

Camphor↗
PubMed1996

[A new approach to the determining immunoglobulin free light chains in serum by TIA nephelometry].

Immunoglobulin light chains exist in two distinct forms, as linked to heavy chains by disulfide bonds, and as free light chains (FLc). Neoplastic B-cell disorders are responsible for the major absolute elevations of FLc, which are almost all monoclonal. Free light chains are nephrotoxic, and patients with renal failure have elevated blood concentrations of FLc. Light chains of immunoglobulins have attracted clinical attention as one of the proteins constituting the amyloid fibrils. Moreover, the concept of light chain deposition disease as independent entity has recently been advocated. In these circumstances TIA nephelometry using commercially available antibodies has been developed for the quantitation of both free kappa and lambda light chains of immunoglobulins in serum. This method is simple and rapid, and enable to analyze a large number of samples at a time, thus the method may be proved to be useful in clinical practice.

Adult↗
PubMed1996

Long-term results and prognostic factors after repair of abdominal aortic aneurysm with concomitant malignancy.

OBJECTIVE: Long-term results after repair of abdominal aortic aneurysm (AAA) with concomitant malignancy were reviewed, and factors which may affect survival were analyzed. DESIGN: Retrospective series with follow-up of three to 125 months. Setting. Department of Surgery, Matsuyama Red Cross Hospital, Matsuyama, Japan. PATIENTS: Among 112 consecutive repairs of AAA, 16 cases had concomitant malignancy. The malignant lesions included eight gastric cancers and eight other malignant tumours. The malignancies were divided using TNM Classification into an early stage (stage O or I) group (n=9) and an advanced stage (stage II, III, or IV) group (n=7). INTERVENTIONS: All aneurysms were successfully repaired, and simultaneous resection of the concomitant malignancy was performed in five cases. While 13 malignant lesions were resected completely, three could not be resected completely, but were treated by other surgical procedures. MEASURES: Survival rates were predicated using the Kaplan-Meier method. The log-rank test was used to compare survival rates. RESULTS: The one-, two-, and five-year survival rates after repair of AAA were 80%, 72% and 63%, respectively. The survival rates for the early stage group were significantly higher than those for the advanced stage group (p<0.05). Patients with concomitant gastric cancer or who underwent complete resection of the malignant lesion survived longer. CONCLUSION: In patients with concomitant AAA and malignancy, factors influencing survival for those with malignant lesions also affected survival after aneurysmectomy. Detection of early-stage concomitant malignancy and more aggressive treatment for the malignancy may improve the outcome.

Age Factors↗
PubMed1996

[Primary autoimmune hemolytic anemia (warm antibody)].

Primary autoimmune hemolytic anemia (warm-reacting auto antibodies), may occur at any age and affects both sexes. The onset may be sudden or insidious. If the hemoglobin has dropped suddenly or to very low level and there is cardio-respiratory emborassment, patient would need a blood transfusion. And a close watch should be kept on urine output, also to keep the urine alkaline. Corticosteroid are the mainstay of treatment. The dose is 1-2 mg/kg/day. The hemoglobin has reached normal level, steroid are reduced 5 mg every week. If patient fails to respond to corticosteroids or the maintenance dose required for corticosteroids causes unacceptable side effects, methylprednisolone pulse therapy, alternative are immunosuppression therapy or splenectomy. As a life saving temporary need, plasmapheresis may be utilized to bring down the titre of antibodies.

Anemia, Hemolytic, Autoimmune↗
PubMed1995

Immunoglobulin free light chain assay using latex agglutination.

Under normal biological conditions, immunoglobulin light chains are generally formed in conjunction with heavy chains; however, small quantities of free light chains are also produced. Thus, two types of immunoglobulin light chains may be identified; immunoglobulin-bound light chains and free light chains. In mature neoplastic B cells, immunoglobulin synthesis, including that of the free light chain, is generally increased. Furthermore, elevated free light chain levels also occur in the presence of renal glomerular and tubular impairment. Thus, the quantitative and qualitative measurement of free light chains is of considerable clinical benefit. Although methods for measurement of free light chains do exist they are technically complicated and time consuming. Previously, we have reported a quantitative nephelometric immunoassay for measuring free light chain levels. We report here a refinement of this method using latex agglutination techniques. This new method enables quantitative measurement of free light chains in serum at levels as low as 1 mg/l and may allow the clinical application of serum free light chain estimation.

Adult↗
PubMed1994

"Module" substitution in hemoglobin subunits. Preparation and characterization of a "chimera beta alpha-subunit".

In the genes of alpha- and beta-subunits of hemoglobin, Go showed that modules F1, F2 + F3, and F4 correspond to exons 1, 2, and 3, respectively (Go, M. (1981) Nature 291, 90). The analysis of the correlation of function with its exon pattern showed that the residues associated with the defined function are concentrated in the specific exons encoding the "module" (Eaton, W.A. (1980) Nature 284, 183). To investigate the functional and structural significance of the "modular structure," we engineered a "chimera" subunit, in which module F4 of the beta-subunit was replaced by that of the alpha-subunit by use of mutagenesis. The NMR and resonance Raman spectra of the isolated "chimera beta alpha-subunit" have revealed that it has a beta-subunit-like heme environmental structure. However, the gel chromatography and NMR spectra of mixtures of the chimera and native subunits clearly showed that the chimera beta alpha-subunit binds specifically to the beta-subunit to form a heterotetramer, not to the alpha-subunit. These results led us to conclude that the predominant role of the module F4 is the subunit association and suggest that the modules are structural and functional units that have advantages in producing stable functional proteins.

Carboxyhemoglobin↗
PubMed1994

Exercise performance in children with hyperthyroidism.

An attempt was made to define exercise performance in children with untreated hyperthyroidism using treadmill stress testing. Data were obtained for five female patients and the results were compared with those obtained for 16 normal female subjects. There were no significant differences at rest between the hyperthyroidism group and the control group in oxygen uptake, minute ventilation and respiratory rate. On the other hand, heart rate in the hyperthyroidism group was significantly higher than that in the control group. During exercise, there were significant differences between the two groups in oxygen uptake, heart rate, minute ventilation and respiratory rate. Hyperthyroid patients did not show an abrupt increase in heart rate during the first 30 s of exercise. Exercise stress testing can therefore reveal cardiopulmonary abnormalities that are not evident at rest in children with hyperthyroidism.

Adolescent↗
PubMed1994

Catecholamine-induced cAMP response in streptozotocin-induced diabetic rat liver.

UNLABELLED: The effect of prolonged diabetic state on catecholamine-induced adenosine 3',5'-monophosphate (cAMP) response in the rat liver was examined using isolated liver perfusion. Epinephrine- or isoproterenol-induced cAMP production was enhanced (10-fold of the control) in the liver from extremely emaciated (intraperitoneal adipose tissue was absent completely) diabetic rats 4 weeks after streptozotocin-injection kept without insulin, but not from adipose tissue-present diabetic rats. Glucagon-induced cAMP production was decreased in the diabetic rat liver 4 weeks after streptozotocin regardless of the presence or absence of adipose tissue. Secretin-induced cAMP production was also decreased in the adipose tissue-absent diabetic rat liver. Plasma levels of glucose or insulin were not different between adipose tissue-present and -absent diabetic rats. Liver dysfunction (elevated AST and ALT levels) was observed 1 week after streptozotocin-injection, and worsened at 4 weeks. Forskolin-induced production of cAMP, and oxymetazoline (an alpha 2-adrenergic agonist)-induced suppression of it were not different among the control, newly diabetic (1 week after streptozotocin-injection), and the adipose tissue-absent diabetic rat liver. IN CONCLUSION: 1) enhanced beta-adrenergic, and decreased glucagon- or secretin-induced cAMP production seems to be caused by different mechanisms; 2) the prolonged severe diabetic state losing adipose tissue may cause a considerable change in metabolism and the characteristics of hepatocyte, and lead to enhanced beta-adrenergic cAMP production.

Adipose Tissue↗
PubMed1993

[Catheter-induced thrombosis of the inferior vena cava--case report].

A 47-year-old woman was admitted for bleeding from gastric ulcer for which a central venous catheter was placed through the right femoral vein. Seven days later, abdominal echograms unexpectedly revealed a large thrombus along the catheter in the inferior vena cava. Because the echograms also disclosed the thrombus immobile even in postural change, the catheter was pulled out. Within two weeks following the catheter removal, the thrombus spontaneously disappeared with no evidence of pulmonary embolism. Although thrombolysis therapy may be the treatment of choice for catheter-induced thrombosis, simple removal of the catheter is effective in case that the thrombus is immobile.

Catheterization, Central Venous↗
PubMed1993

[A case of giant advanced breast cancer responding remarkably to CEFT therapy].

A fifty-two-year-old female was admitted with unresectable advanced giant breast cancer, which was attached to the chest wall and had a bone metastasis to the thoracic vertebrae. At first, depression and fixation were performed for the bone metastasis, and 2 courses of CEFT therapy were administered. One course was intra-arterial chemotherapy. After 2 courses of treatment, the tumor size was not changed, but tumor marker, CT and physical findings showed a remarkable improvement, and mastectomy could be performed. It was suggested that this regimen is very effective for advanced giant breast cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Clinicopathologic evaluation of recurrence in early gastric cancer.

Five hundred ninety-two patients with early gastric cancer underwent surgical resection from 1970 to 1986 in our hospital, and 13 died from a recurrence of their disease. A careful analysis of these 13 patients suggests that carcinomas which invaded to the submucosa tend to recur more often than those confined to the mucosa. Well differentiated and papillary adenocarcinomas characterized by protruded or elevated lesions tend to recur earlier than poorly differentiated or signet-ring cell carcinomas characterized by depressed or excavated lesions. However, both types recurred from hematogenous metastases, with the liver being the most common site. Therefore, the macroscopic and histological features presently used to characterize early gastric cancer do not provide sufficient information to accurately predict which patients are at most risk for recurrence.

Adenocarcinoma↗
PubMed1992

[Clinical evaluation of sulbactam/cefoperazone for severe infections associated with hematological disorders].

The combination therapy of sulbactam/cefoperazone (SBT/CPZ) and piperacillin (PIPC) was evaluated in 49 patients with severe infections associated with hematological disorders. Clinical responses in 43 evaluable patients out of the 49 patients were excellent in 12, good in 18, thus, overall efficacy rate was 69.8% (excellent plus good). Efficacy rates of this combination therapy were 60% (3/5) for sepsis, 75% (21/28) for suspected sepsis, and 50% (4/8) for pneumonia. The efficacy rate was 71.4% (10/14) in patients with neutrophil counts less than 200/microliters; this combination therapy was highly effective even in the neutropenic patients. Transient increases in hepatic function test values were observed in 2 patients, but no other side effects were observed during the combination therapy. From these observations it appears that the combination therapy of SBT/CPZ and PIPC is a very useful empiric therapy for severe infections associated with hematological diseases.

Adolescent↗