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Biomedical subjects

Y Mikami

Publications and source records attributed to Y Mikami.

At least 91 records · Page 5Linked to original sources
PubMed2000

Effect of mental stress on left ventricular ejection fraction and its relationship to the severity of coronary artery disease.

To evaluate the relationship between the mental stress-induced decrease in left ventricular ejection fraction (LVEF) and the severity of exercise-induced ischaemia, 20 patients with stable coronary artery disease (CAD) underwent radionuclide ventriculography during mental stress testing and stress myocardial perfusion single-photon emission tomography (SPET). We also examined whether changes in haemodynamic and neurohormonal parameters are related to changes in LVEF during mental stress. The LVEF decreased from 54.8% +/- 17.7% to 49.8% +/- 16.2% with mental stress (P < 0.0005). Ten of the 20 patients (50.0%) had a > or = 5% decrease in LVEF The remaining ten patients had no or a <5% decrease in LVEF There was a significant correlation between the change in LVEF during mental stress and the size of the reversible defect on stress myocardial perfusion SPET (r = -0.80, P < 0.0005), with close regional correspondence (75% identical). This correlation was less strong in the 12 patients with a total defect score at rest of <10 (r = -0.69, P = 0.014) than in the eight patients with a total defect score at rest of > or = 10 (r = -0.94, P = 0.001). The changes in blood pressure and heart rate were not significantly correlated with the change in LVEF, but the percent change in adrenaline concentration correlated with the change in LVEE It is suggested that mental stress impairs systolic function by inducing transient myocardial ischaemia. The effect of neurohormonal responses during mental stress on LV systolic function may also be important in patients with CAD.

Aged↗
PubMed2000

Nasal NK/T cell lymphoma presenting as transverse myelopathy.

A case of nasal NK/T cell lymphoma with central nervous system (CNS) involvement is reported. A 56-year-old man presented with eyelid edema and transverse myelopathy. Cerebrospinal fluid examination revealed atypical lymphoid cells with azurophilic granules, which were positive for CD2, CD8, and CD56, and negative for CD3 and CD5 by flow cytometry. Because a tumor mass was found involving the ethmoid and maxillary sinuses, CNS involvement was considered to have resulted from local invasion by the nasal lymphoma. In spite of intensive chemotherapy including intrathecal infusion, the patient died 6 months after the initial diagnosis. Autopsy revealed that lymphoma cells were positive for cytotoxic molecules, granzyme B and TIA-1, and EB virus-encoded RNA-1 (EBER-1), and they showed no rearrangement of TCR-beta, -gamma, or -delta genes, suggesting an NK-cell origin of the lymphoma cells. They showed an angiocentric and angiodestructive pattern in the subarachnoid space, focally extending to the cerebral cortex and cranial and spinal nerve roots. Marked demyelination was found in the lateral and posterior funiculi of the spinal cord. Thus, the pathogenesis of this spinal demyelination might be attributed to ischemia secondary to angiocentric and angiodestructive infiltration by lymphoma cells.

Diagnosis, Differential↗
PubMed2000

Hepatic resection using the harmonic scalpel.

We describe herein our technique of performing extensive resection of the liver by blunt dissection in combination with excision using a harmonic scalpel. A ball coagulator was inserted at 3-cm intervals along the proposed cutting line in the liver, and the liver parenchyma between these holes was then cut using coagulation shears. Regardless of the condition of the liver, good coagulation and cutting were achieved using the harmonic scalpel without vascular occlusion when dividing the shallow layer of the liver, and no complications in association with the harmonic scalpel, such as postoperative bleeding, bile leakage, or abscess formation at the cut margins, occurred. In the deep layer below the main trunk of the hepatic vein, blunt dissection was used, since it was difficult to achieve sufficient control of bleeding from large vessels using the harmonic scalpel alone. Therefore, when used in combination with other techniques, the harmonic scalpel appears to be an effective device for liver surgery that minimizes bleeding and decreases the vascular clamping time.

Adult↗
PubMed2000

The effect of atorvastatin on serum lipids and lipoproteins in patients with homozyous familial hypercholesterolemia undergoing LDL-apheresis therapy.

The efficacy of atorvastatin, a new hydroxymethylglutaryl (HMG)-CoA reductase inhibitor, in reducing serum lipid levels, modifying lipoprotein composition, and suppressing cholesterol synthesis was evaluated in patients with homozygous familial hypercholesterolemia (homozygous FH) undergoing LDL-apheresis therapy. Atorvastatin was given in escalating doses (10, 20, and 40 mg/day) to nine patients with homozygous FH. Five of nine patients responded well to atorvastatin; four of these patients were receptor-defective and the remaining one was receptor-negative. The change in LDL-cholesterol in the receptor-defective patients averaged -20.6% compared to the baseline level at the highest dose of atorvastatin. Of five receptor-negative type patients, only one showed good response to atorvastatin therapy with a LDL-cholesterol reduction of 14.9%. Although the other four receptor-negative patients did not show a change in LDL-cholesterol, all of them exhibited a considerable increase in HDL-cholesterol. All patients showed reduced urinary excretion of mevalonic acid, suggesting that atorvastatin decreases LDL-cholesterol by inhibiting cholesterol biosynthesis even where LDL-receptor activity is not present. Atorvastatin also decreased serum triglycerides in both receptor-negative and defective patients, especially in the latter. As cholesterol level rebounds quickly after each apheresis procedure, a combination therapy using atorvastatin and apheresis may increase the efficacy of the apheresis treatment, improving cost-benefit effectiveness by reducing the frequency of the apheresis treatment.

Adolescent↗
PubMed2000

Malignant peripheral nerve sheath tumor arising in benign ancient schwannoma: a case report with an immunohistochemical study.

A rare example of malignant transformation in an ancient schwannoma arising in the right side of the neck of a 51-year-old man without any clinical manifestations suggesting neurofibromatosis is described. The tumor, approximately 4 cm at its largest dimension, was well circumscribed and had a direct connection with the sympathetic nerve. Microscopically, the central portion of the tumor showed features of ancient schwannoma characterized by extensive hyalinization with cystic degeneration, scattered spindle cells with hyperchromatic and tapered nuclei, and some symplastic changes. However, predominantly in the outer portion, a proliferation of spindle-shaped cells with enlarged nuclei was present. The nuclei of these cells showed irregular contours, coarse granular chromatin texture, and conspicuous nucleoli. Mitotic figures and small necrotic foci with scattered apoptotic bodies were also seen. Immunohistochemically, S-100 protein was almost negative in areas consisting of overtly atypical cells where the mitotic index evaluated with MIB-1 antibody was 30.5%. In contrast, S-100-positive bland spindle cells were scattered in an extensively hyalinized area with a labeling index less than 3%. P53 protein was strongly positive in atypical spindle cells. Although it is a very uncommon event, definite nuclear atypia, frequent mitotic figures, and the existence of small necrotic foci should be recognized as indicating a diagnosis of malignant degeneration of benign schwannoma. Immunohistochemistry would be useful as an ancillary technique in such a setting.

Biomarkers, Tumor↗
PubMed2000

A new PCR primer for the identification of Paracoccidioides brasiliensis based on rRNA sequences coding the internal transcribed spacers (ITS) and 5 x 8S regions.

Internal transcribed spacer (ITS) genes including the 5.8S ribosomal (r)RNA of Paracoccidioides brasiliensis were amplified and the DNA sequences were determined. Based on a comparison of the sequence information, a new polymerase chain reaction (PCR) primer pair was designed for specific amplification of DNA for P. brasiliensis. This primer pair amplified a 418-bp DNA sequence and was 100% successful in identifying 29 strains of P. brasiliensis (including the reference strains) isolated from the regions of Brazil, Costa Rica, Japan, Argentina or from different sources. The results of specificity tests of these primers to compare the fungus with those of Aspergillus fumigatus, Blastomyces dermatitidis, Candida albicans, Cryptococcus neoformans, Histoplasma capsulatum and Penicillium marneffei are also reported.

DNA Primers↗
PubMed2000

Pyrinodemins B-D, potent cytotoxic bis-pyridine alkaloids from marine sponge amphimedon sp.

New bis-pyridine alkaloids, pyrinodemins B-D (1-3), have been isolated together with pyrinodemin A (4) and related 3-alkyl pyridine alkaloids 5-8 from the Okinawan marine sponge Amphimedon sp. and the structures were elucidated from spectroscopic data. Pyrinodemins B-D (1-3) showed potent cytotoxicity, while compounds 5-8 exhibited antimicrobial activity.

Alkaloids↗
PubMed2000

Serum levels of soluble interleukin-2 receptor after bone marrow transplantation: a true marker of acute graft-versus-host disease.

To examine whether serum levels of soluble interleukin-2 receptor (sIL-2R) may be a good marker of acute graft-versus-host disease (aGVHD), they were determined weekly in 56 patients receiving bone marrow transplantation (BMT). Because of wide variation in the pre-transplant sIL-2R levels (from 135 to 1918 IU/ml), we used a sIL-2R index in this study by comparing the peak levels with the pre-transplant levels. In agreement with previous reports, there was a significant correlation between the grade of aGVHD and the maximal sIL-2R index. The maximal sIL-2R index was 4.66 in patients with grade I to IV aGVHD, whereas it was 2.68 in patients without GVHD. This marker may be useful for monitoring the status of aGVHD. However, it was interesting that sIL-2R levels were elevated from the time of transplantation until the third week even in patients without GVHD or those who received autologous transplantation. Until the third week, no significant differences were observed in sIL-2R index between these patients and those who developed aGVHD during their clinical courses. After the fourth week, a higher sIL-2R index was observed in patients with aGVHD than in the other patients. Some factors other than GVHD contribute to the elevation of serum sIL-2R levels, and we should recognize the limitations of the measurement of this cytokine.

Adolescent↗
PubMed2000

[Ultrasonographic evaluation of metastatic cervical lymph nodes in head and neck cancers].

This study evaluates the use of ultrasonography (USG) to diagnose metastatic cervical lymph nodes. Three-hundred and one lymph nodes were removed from 58 patients with squamous cell carcinomas of the head and neck. None of the patients had received any preoperative treatments for cancer. The lymph nodes were then histopathologically examined: 139 metastatic lymph nodes and 162 non-metastatic nodes were found. USG was then used to evaluate the size, internal echo, and margin of each lymph node. Size was found to be the best criteria for distinguishing metastatic lymph nodes from non-metastatic lymph nodes in all cervical regions (78% accuracy). Superior internal jugular lymph nodes and submandibular lymph nodes larger than 7 mm and mid and inferior internal jugular lymph nodes larger than 6 mm were regarded as metastatic. Internal echoes were classified into five patterns: homogeneous hypoechoic, homogeneous hyperechoic, heterogeneous, eccentric hyperechoic, and centric hyperechoic. Homogeneous hyperechoic and heterogeneous patterns were characteristic of metastatic nodes, while eccentric hyperechoic patterns were characteristic of non-metastatic nodes. Homogeneous hypoechoic patterns were observed in both metastatic and non-metastatic nodes. Regular margins were found in 81% of the metastatic nodes. Of the 22 lymph nodes with irregular margins, however, 91% were metastatic. Evaluations using a combination of USG and clinical feature criteria were compared with evaluations using only thickness as a criterium. Although thickness is the single most important factor in diagnosing metastatic nodes, the combination of USG and clinical feature criteria improved the accuracy of diagnosis to 83%. Thus, diagnostic methods involving a combination of several criteria are more accurate than methods involving only a single criterium.

Carcinoma, Squamous Cell↗
PubMed2000

Structures of ADP-ribosylated rifampicin and its metabolite: intermediates of rifampicin-ribosylation by Mycobacterium smegmatis DSM43756.

23-(O-ADP-Ribosyl)rifampicin [RIP-TAs (3, Na+ form), RIP-TAf (4, H+ form)] was obtained as an intermediate in the conversion process of rifampicin (1) to RIP-Mb (2) that is mediated by cell homogenates of Mycobacterium smegmatis DSM43756 or of Escherichia coli carrying a mycobacterial mono(ADP-ribosyl) transferase gene, in the presence of NADH. 23-[O-(5'-Phosphoribosyl)]rifampicin (5, RIP-TAp) was also obtained by the reaction of rifampicin with NADH in the presence of a homogenate of M. smegmatis. The structures of 3, 4, and 5 were determined by means of MS and NMR analyses.

ADP Ribose Transferases↗