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Biomedical subjects

H Masaki

Publications and source records attributed to H Masaki.

At least 109 records · Page 6Linked to original sources
PubMed1997

[Coagulase typing of Staphylococcus aureus in the geriatric wards after introduction of preventive measures of hospital infection].

In the early 1980's methicillin-resistant Staphylococcus aureus (MRSA) was reported as a major pathogenic organism of geriatric hospital infection in Japan. At the same time in our geriatric wards, including 190 beds, MRSA infection was prevalent. In the early 1980's in our geriatric wards minocycline was one of the most sensitive antibiotics to MRSA isolated in our wards and used frequently against MRSA pneumonias and bacteremia. In the late 1980's resistant strains of MRSA to minocycline rapidly increased because vancomycin was not allowed to introduced for treatment of MRSA before 1991 in Japan. At the same period the predominant coagulase type changed from type II to type VII. To decrease minocycline-resistant strains to MRSA after 1987, use of minocycline was limited. Moreover since Oct. 1991 to decrease nosocomial infections some active preventive measures against hospital infection, including limited use of 2nd and 3rd cephems, were taken. In this study changing patterns of coagulase type of Staphylococcus aureus were discussed. At least 4 years was needed to find out that the predominant coagulase type changed from type VII to type II again in 1991. In this study about 22 antimicrobial agents MICs of 313 strains of Staphylococcus aureus isolated between March 1992 and June 1993 were determined and compared with the data of MICs before introduction of preventive measures. The pattern of susceptibility to MINO was in part improved. Thus the some sensitive strains of S. aureus were observed again in our geriatric wards. Interestingly indeed it took approximately 5 years to find out the emergence of sensitive strains to MINO since limitation of use of MINO in 1987.

Bacterial Typing Techniques↗
PubMed1997

[A clinical study of skin flora in patients with MRSA colonization after introduction of preventive measures of hospital infection in a geriatric ward].

In early 1980's methicillin-resistant Staphylococcus aureus (MRSA) was reported as a major pathogenic organism of geriatric hospital infection in Japan. At the same time in the geriatric hospital MRSA infection was prevalent. To decrease nosocomial infections some active preventive measures against hospital infection were taken since Oct. 1991. After introduction of preventive measures of hospital infection in the geriatric ward (190 beds) nosocomial bacteremia and pneumonia were markedly decreased in comparison of episode number before introduction of prevention. However several patients with MRSA colonization were observed every month. The aim of this clinical study was to clear how frequent MRSA was isolated from skin. Consequently 3 strains (3.4%) of MRSA were observed in 86 cultured skin. In conclusion we considered frequency of MRSA colonization frequency of MRSA colonization on skin was not so high but rather very low under the preventive measures.

Aged↗
PubMed1997

Phospholamban deficiency alters inactivation kinetics of L-type Ca2+ channels in mouse ventricular myocytes.

Entry of Ca2+ through voltage-dependent L-type Ca2+ channels is critical for contraction in cardiac cells. In recent studies, cells from phospholamban (PLB) knockout (PLB-KO) mouse hearts showed significantly increased basal contractility with enhanced sarcoplasmic reticulum (SR) Ca2+ uptake. To test whether these effects of PLB ablation were associated with alterations of L-type Ca2+ channel function, we compared the properties of Ca2+ channel currents (I(Ca)) in ventricular myocytes isolated from wild-type (WT) and PLB-KO mouse hearts. L-type Ca2+ channels from mouse myocytes exhibited voltage-dependent gating and sensitivity to dihydropyridine drugs, similar to other mammalian species, and these properties were not altered by PLB ablation. I(Ca) from both WT and PLB-KO cells revealed two (fast and slow) components of inactivation kinetics. However, the proportion of the faster component was significantly larger in PLB-KO cells. Ryanodine (10 microM) reduced the rate of inactivation of I(Ca) for both WT and PLB-KO cells, but the reduction was more prominent in PLB-KO cells compared with WT cells. In contrast, the inactivation in a Ba2+ solution could be fitted by a single exponential similar to the slower component in Ca2+, and this was not altered in PLB-KO cells. The increase in the fast Ca2+-dependent inactivation component in PLB-KO cells supports the hypothesis that Ca2+ released from the SR regulates Ca2+ channel inactivation by affecting the levels of Ca2+ near the channel and suggests that this may be an important compensatory mechanism in the hyperdynamic PLB-KO heart.

Animals↗
PubMed1997

Protective effects of hydroxybenzoic acids and their esters on cell damage induced by hydroxyl radicals and hydrogen peroxides.

The purpose of this study was to evaluate the hydroxyl radical scavenging activities of hydroxybenzoic acids and their esters from both chemical and biological aspects. These activities of hydroxybenzoic acids and their related compounds were estimated by ESR-spin trapping method, in which 3,4,5-trihydroxybenzoic acid and its ethyl and propyl esters showed the highest activities as estimated by IC50 value (50% inhibition concentration of hydroxyl radicals generated in the system): 78.04 +/- 11.23, 95.95 +/- 2.64, and 86.46 +/- 2.31 microM, respectively. In addition, 3,4,5-trihydroxybenzoic acid (gallic acid) at a concentration of 25 microM, protected against dermal fibroblast cell damage induced by H2O2, and enhanced the survival to 83.8 +/- 3.1%, in which the survival of control was 44.2 +/- 1.0%. Based on these results, the pretreatment effects of 3,4,5-trihydroxybenzoic acid n-alkyl esters on cell damage induced by H2O2 were examined. The survival of fibroblasts pretreated with the esters increased depending on the alkyl chain-length. Both C12 and C16 alkyl esters gave almost complete cell survival of 89.5 +/- 2.0% and 91.3 +/- 1.0%, respectively. The order of the protective effects of the compounds was in good agreement with that of their partition coefficients, suggesting that 3,4,5-trihydroxybenzoic acid alkyl esters are incorporated into fibroblasts, and thus prevent the cells from the toxicity caused by H2O2. In addition, an increase of intracellular peroxide formation in fibroblasts induced by UVA-irradiation, was suppressed to 2.27 +/- 0.41 nmol/10(4) cells by pretreatment with C16 alkyl ester at a concentration of 25 microM. Since 3,4,5-trihydroxybenzoic group has been demonstrated to possess a potent scavenging activity of hydroxyl radicals, this moiety was indicated to be important in preventing cell damage induced by UVA or H2O2: in turn, these produce hydroxyl radicals in the presence of trace metal ions such as iron and copper in cells.

Cell Survival↗
PubMed1997

Mutational analysis of the potato virus Y 5' untranslated region for alteration in translational enhancement in tobacco protoplasts.

The 185 nucleotide 5' untranslated region (5'UTR) of potato virus Y ordinary strain (PVY-O) showed translation-enhancing activity on the beta-glucuronidase (GUS) gene in tobacco protoplasts. Mutational analysis of the 5'UTR was done to find sequence motifs necessary for the enhancement. Deletions within the 1-130 nucleotide region of 5'UTR stimulated the GUS expression in some cases, while the GUS activity declined with deletions in the 131-185 nucleotide region. The results indicated that the last 55 nucleotides of PVY-O 5'UTR might play the much important role in the translational enhancement in plant cells.

Amino Acid Sequence↗
PubMed1997

Cloning, sequencing, and expression of a thermostable cellulase gene of Humicola grisea.

The egl2 gene coding a thermostable endoglucanase (EGL2) was cloned from Humicola grisea. The DNA sequence of egl2 predicted two putative introns in the coding region. The deduced amino acid sequence of EGL2 was 388 amino acids in length and showed 99.5% identity with the H. insolens CMC 3. In addition to TATA box and CAAT motifs, putative CREA binding sites were observed in the 5' upstream region of the egl2 gene. The egl2 gene was expressed in Aspergillus oryzae, and EGL2 was purified. EGL2 produced by A. oryzae showed a high activity toward carboxymethyl cellulose. The optimal temperature of EGL2 was 75 degrees C, and EGL2 had more than 80% residual activity after heating up to 75 degrees C for 10 min. This is the first report of enzymatic properties of the EGL2-type thermostable cellulase homologs from Humicola.

Amino Acid Sequence↗
PubMed1997

Oxygen sensitivity of NifA protein of Azospirillum lipoferum FS as suggested by gene cloning and expression in Escherichia coli.

We cloned and sequenced a 2.8-kb SalI fragment of Azospirillum lipoferum FS as a homologue of the Klebsiella oxytoca nifA gene. The amino acid sequence deduced from an open reading frame of 1872 bases showed 91% identity to that of the A. brasilense NifA, and the putative central sigma54 interaction domain was conserved as well as the C-terminal DNA-binding domain. The NifA function on the nifH promoter was examined in Escherichia coli using a combination of a nifA driver plasmid and a nifH-lacZ reporter plasmid, in which the transcriptional activation of the nifH promoter by the NifA was evaluated with the beta-galactosidase activity. The A. lipoferum NifA activated the nifH promoter solely under microaerobic conditions, while the K. oxytoca NifA activated it irrespective of the oxygen condition. These observations suggest that oxygen sensitivity is an intrinsic property of the A. lipoferum NifA.

Amino Acid Sequence↗
PubMed1997

[A case report of malignant schwannoma of the chest wall].

We described a very rare case of malignant schwannoma of the chest wall, which was surgically resected. The patient, a 40-year-old woman, came to our hospital because of an abnormal shadow in the right chest wall of an X-ray film without any symptoms. Computed tomography revealed a solid tumor attached to the posteroinferior aspect of the intrathoracic chest wall. The tumor was a 2.5 x 2.1 cm, mass originating from the seventh intercostal nerve without pulmonary adhesion, and the patient underwent en bloc resection of the tumor. The pathological diagnosis was malignant schwannoma. The postoperative course was uneventful, and the patient, eight years after the operation is now doing well without local recurrence or distant metastasis. We reviewed seven cases of this type of tumor reported in the Japanese literature.

Adult↗
PubMed1997

[Recurrent intrathoracic dissemination of thymoma with myasthenia gravis: a case report].

A 48-year-old man was readmitted to our hospital with a chief complaint of left anterior chest mass. He had a past history of thymo-thymomectomy six years earlier. On chest CT examination, multiple tumor shadows were noted within the left thoracic cavity. All visible tumors were resected. His postoperative course was favorable, and no signs of recurrence have been recognized on CT to date (three years and six months postoperatively). However, in view of the possible recurrence of the present disease after a long period, strict observation of the course of the disease is necessary.

Humans↗
PubMed1997

[Organ preservation in the treatment of malignant solid tumors in children].

Organ preservation is one of the requirements for maintaining the high quality of life after the treatment of malignant solid tumors in children. We analyze our recent results of renal preservation in the abdominal neuroblastoma and describe 3 cases of successful organ preservation in pelvic malignancy. Between 1982 and 1996, 29 patients with adrenal or retroperitoneal neuroblastoma, that extended into the surrounding tissues and organs and/or to the contralateral side, underwent delayed primary excision. Before 1982, 9 patients were treated and only one ipsilateral kidney was preserved. On the other hand, 13 of 20 kidneys were preserved after 1987. Adoption of cis-platinum deepened our awareness of preserving the kidney. Furthermore, we have altered our strategy since 1987 to continuing preoperative chemotherapy until the size of the tumor becomes as small as it is estimated completely resectable by our own index, which is derived from computed tomography. Kidneys are shielded during intraoperative irradiation, and the tumor relapsed from the shielded area of retroperitoneum in one patient. Four of 14 preserved kidneys became atrophic and lost their function. The bladder and the rectum were left intact at tumor resection after intensive chemotherapy in two patients with pelvic (one retroperitoneal and one vaginal) rhabdomyosarcoma. A yolk sac tumor of the vagina responded completely to chemotherapy with cis-platinum, etoposide and bleomycin. The patient has survived 7.5 years without any local and distant relapse in spite of the fact that surgery, aside from several diagnostic biopsies, was not undertaken.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

[Ruptured descending thoracic aortic aneurysm due to aortitis syndrome--a case report].

Ruptured fusiform descending thoracic aortic aneurysms due to aortitis syndrome are rare. A 29-year-old woman was readmitted to our hospital with a chief complaint of back pain and shock, and diagnosed as having rupture of a descending thoracic aortic aneurysm. She had a past history of aortitis syndrome beginning eight years ago. On chest CT examination earlier a year, the descending thoracic aortic aneurysm was 4.5 cm in diameter, and calcification we observed in the aortic wall. An inflammatory reaction had been controlled by steroid therapy and her blood pressure had been controlled by vasodilator drugs. Emergent graft replacement of a descending aortic aneurysm was successfully performed under a femoro-femoral bypass using a centrifugal pump and membrane oxygenerator, and Cell Sver. Although in the literature surgical treatment is indicated only if there is a symptomatic or enlarging aneurysm especially of saccular type and no operation is justified for an aortic aneurysm showing marked calcification, we concluded that aggressive surgical treatment was necessary for this fusiform aneurysm due to aortitis syndrome.

Adult↗
PubMed1997

[Blood cyst of the pulmonary valve in an adult--a case report].

Blood cysts of the heart valves are commonly reported at postmortem examination of infants but are rare seen in older children and adults. A 42-year-old woman was referred to our hospital for cardiac evaluation because of dyspnea on exertion and heart murmur. There was no history of cyanosis or cardiac failure. Cardiac catheterization revealed valvular pulmonary stenosis and atrial septal defect. Right ventricular angiography showed the circular filling defect 0.7 x 0.7 cm in size at the suprapulmonary valve. However, this preoperative abnormal finding was diagnosed as a blood cyst after surgery. At operation a blood cyst originating from the right cusp of the pulmonary valve was found and resected, and was followed by commissurotomy of the pulmonary valve and direct closure of the atrial septal defect. Her postoperative course was uneventful.

Adult↗
PubMed1997

The diagnosis and management of splanchnic artery aneurysms. Report of 8 cases.

The purpose of this report is to describe the clinical characteristics and surgical technique for splanchnic artery aneurysms. Over the past 10 years we have surgically resected 8 cases of splanchnic artery aneurysms including 2 cases involving the superior mesenteric artery, 3 involving the renal artery, 1 involving the hepatic artery and 2 involving the splenic artery. Diagnosis was established preoperatively in all patients by splanchnic angiography. Surgical treatment for splanchnic artery aneurysms is indicated in any symptomatic patient, in all symptomatic patients with suspected renal aneurysmal expansion and in patients who have renal aneurysms occurring with functionally important renal stenosis, usually associated with hypertension, in all patients with surgical accessible hepatic artery aneurysms, in all patients who have superior mesenteric artery aneurysms having a high tendency to rupture, and in all patients with an asymptomatic splenic artery aneurysms 1.5 cm or larger in diameter. Although splanchnic artery aneurysms are uncommon and asymptomatic, we recommend that splanchnic arteries should be treated surgically because of their tendency to rupture or organ failure.

Adult↗
PubMed1997

[Brain damage after surgery for thoracic aortic aneurysm].

We analyzed cases with brain damage after surgery for thoracic aortic aneurysm in our institution and investigated the causes, risk-factors and preventive measures for this disastrous postoperative complication. Irreversible brain damage was a complication in 25 out of 184 operative cases (13.6%) over a 21-year period. The cause of brain damage was determined to be embolism by manipulation of the aorta in six cases, clamping of the left subclavian artery in four cases, technical problems of separate cerebral perfusion (SCP) in four cases, severe shock in three cases, embolism unrelated to operative maneuver in three cases, stenosis of a branch of the arch with aortic dissection in two cases, and air embolism, circulatory arrest with insufficient hypothermia and hypoperfusion of a temporary bypass to the left carotid artery in one case each. The neurological symptom improved in eight cases and was unchanged in 17 cases. Eighteen cases died in the hospital. In the univariate analysis, age (p = 0.048), a portion of the aneurysm (p = 0.035), preoperative brain complication (p = 0.003), emergency operation (p = 0.033) and clamping of the arch (p = 0.001) were found to be prominent risk factors for brain damage. In the multivariate analysis, clamping of the arch (p = 0.0310), SCP (p = 0.0327) and emergency operation (p = 0.0223) were prominent. To prevent postoperative brain damage, the arch should not be clamped, appropriate operative techniques to avoid bleeding and to shorten SCP time should be employed, and proper and prompt management of the emergency operation and caution in clamping the left subclavian artery are considered to be necessary.

Adult↗
PubMed1997

Characterization of the I-E(d)--restricted peptide recognized by an anti-idiotypic CD4+ T cell line.

We have previously reported a CD3+ CD4+ CD8- T cell line, J-2R which specifically recognized J558 individual idiotope (IdI) of anti-alpha (1-->3) dextran antibodies in an I-E(d) restricted manner. The J-2R proliferated in response to J558 IdI-derived peptides; however, the ability of the peptides to evoke the proliferation of J-2R was different. In the present study, we investigated the interaction between J558 IdI-derived peptides and I-E(d) molecules in competition experiments using a M104E IdI-derived peptide, M88-105. The M88-105 inhibited the proliferation of J-2R induced by J558 IdI-derived peptides. Furthermore, the proliferation induced by the peptides J92-109 and J96-105 was inhibited by the M88-105 at much lower inhibitor/antigenic peptide ratios, compared to the proliferation induced by the J88-105. Thus, shift of the framework to C-terminus and deletion of N-terminus amino acid residues from the 18-mer peptide J88-105 made the peptides more susceptible to the inhibition by the M88-105. Sequencing of the J-2R T cell receptor (TcR) revealed that J-2R used TcR, V alpha 1, J alpha 44; V beta 15, D beta 1, J beta 1.5. These results suggest that the peptides, J88-105, J92-109 and J96-105, directly bind to I-E(d) molecules, and that the capacity of J558 IdI-derived peptides to activate J-2R depends on the affinity to the I-E(d) molecules.

Amino Acid Sequence↗
PubMed1996

Establishment and characterization of an anti-idiotypic CD4+ CD8- T cell line to murine anti-alpha(1 --> 3) dextran antibody.

It is known that anti-alpha(1 --> 3) dextran antibodies of BALB/c mice are ordinarily of distinctive idiotypes (Id), one of which is the individual idiotype (IdI) that is represented by J558 or M104E to myeloma protein. In the present study, we established T cell line of Th1 type which recognized the Id of anti-alpha(1 --> 3) dextran antibody, and investigated its specificity and functions. The T cell line, named J-2R, had a phenotype of CD3+ CD4+ CD8- and expressed alphabeta-T cell receptors (TcR). J-2R proliferated in response to J558 in an I-Ed-restricted manner but did not respond to M104E which had substitution at amino acids 100 and 101. We confirmed that J-2R recognized J558 IdI, using synthetic peptides corresponding to two serial amino acid residues, Arg100 and Tyr101, spanning the J558 IdI in the third hypervariable region (hv3) of the heavy chain. alpha(1 --> 3) dextran-binding B cells which were isolated from dextran-immunized mice activated J-2R, but B cells from nonimmune mice did not. J-2R produced IL-2, IFN-gamma and IL-6, but did not produce IL-4, IL-5, or IL-10. Furthermore, J-2R inhibited the growth of J558 myeloma cells inoculated to the syngeneic mice in vivo. These findings suggest that Id-specific CD4+ T cells, J-2R, are involved in Id network and may play a role in vivo. J-2R is useful for analysis of the role of the Id-specific helper T cells in immune network because J558 IdI is frequently present on anti-alpha(1 --> 3) dextran antibodies.

Amino Acid Sequence↗