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Biomedical subjects

N Ishikawa

Publications and source records attributed to N Ishikawa.

At least 145 records · Page 8Linked to original sources

Effect of functional continuous magnetic stimulation on urethral closure in healthy volunteers.

OBJECTIVES: To study urodynamically the effect of functional continuous magnetic stimulation on urethral closure in normal volunteers. METHODS: Ten volunteers (6 men and 4 women, 20 to 29 years old, mean age 24.5) were recruited for the study. Seven subjects were assigned to an active group and 3 to a sham group. An 8F transducer was inserted transurethrally, and the urethral pressure profile was monitored. Then the catheter was fixed so that the transducer could be positioned at the portion at which the highest pressure was recorded (maximum intraurethral pressure). In the active group, the stimulating intensity was gradually increased up to the tolerable limit. A 15-minute single session of stimulation was carried out at 20 Hz in an intermittent manner with 1-minute-on/30-second-off cycles. After stimulation, the urethral pressure profile was repeated. RESULTS: In the active group, the greatest pressure difference between the on and off phases of the maximum intraurethral pressure was 62.4+/-37.6 cm H2O at 35% to 55% of maximum output (46 to 113 J). In the urethral pressure profile, the maximum urethral closure pressure increased significantly after stimulation (P = 0.0280). In the sham group, no changes in these parameters were noted. All subjects tolerated the functional continuous magnetic stimulation well, and none experienced any adverse effect. CONCLUSIONS: Functional continuous magnetic stimulation safely and significantly increased maximum intraurethral pressure during stimulation and maximum urethral closure pressure after stimulation.

Adult↗

Meningioma of the internal auditory canal with extension into the vestibule.

Meningiomas account for approximately 18 to 19 per cent of all brain tumours. Although they can arise in numerous locations, meningiomas of the internal auditory canal (IAC) are rare. Most tumours that originate in the IAC are schwannomas of the VIIIth cranial nerve (acoustic neuromas). We report a case of a meningioma which appears to originate from the IAC and extends into the vestibule. The clinical findings and the radiographical features of meningiomas of the IAC are similar to those of acoustic neuromas. Pre-operative differentiation between acoustic neuromas and meningiomas of the IAC may be difficult.

Diagnosis, Differential↗

In-situ observation of shape and atomic structure of Xe nanocrystals embedded in aluminium.

An imaging technique to determine in situ the shape and atomic structure of nanosized Xe crystals embedded in Al is described using high-resolution transmission electron microscopy (HRTEM). The Xe nanocrystals, with sizes less than 5 nm were prepared by the implantation of 30 keV Xe+ into Al at room temperature. The fcc Xe nanocrystals are mesotactic with the Al lattice and have a lattice parameter approximately 50% larger than that of Al. HRTEM images of the Xe were not clear in [110] zone axis illumination because of the small number of Xe atoms relative to Al atoms in any atom column. An off-axial imaging technique that consists of tilting the specimen several degrees from a zone axis and defocusing to suppress the Al lattice fringes is employed for the 110 projection of the Xe/Al system and the structure of the Xe nanocrystals is successfully imaged. The Xe images clearly represent projections of cuboctahedra with faces parallel to eight Al {111} planes truncated by six {100} planes. The results of multislice image simulations using a three-dimensional atomic model agreed well with the results obtained by the off-axial imaging technique. The usefulness of the technique is demonstrated with observations of crystal defects introduced into the Xe under intense 1000 keV electron irradiation.

Journal Article↗

Metabolic characteristics of the elderly with recurrent calcium oxalate stones.

OBJECTIVE: To determine the metabolic characteristics of elderly patients with recurrent calcium oxalate stones. PATIENTS AND METHODS: Metabolic abnormalities were investigated in 88 patients with recurrent calcium oxalate stones, including 70 aged <60 years and 18 aged >/=60 years. The frequency of each metabolic abnormality and the value of each urinary constituent were compared among subgroups of age and gender. RESULTS: Hyperoxaluria was the most common abnormality, present in 56% and 67% of patients aged <60 and >/=60 years, respectively. Hyperuricosuria was significantly more common in older than in younger patients. There were no significant differences in the frequencies of hypercalciuria and hypocitraturia between the age groups. The urinary excretion of oxalate and the ratio of oxalate to creatinine were significantly greater in older than in younger men. The frequency of low urine volume was lower in older than in younger patients and the mean urinary volume was also greater in the older group. CONCLUSIONS: Hyperuricosuria and hyperoxaluria seem to be essential risk factors for calcium oxalate stone formation in elderly patients. Urinary oxalate excretion is significantly greater in older than in younger stone formers and is more prominent in men.

Adult↗

Primary cultures of human endothelial cells are susceptible to low doses of Shiga toxins and undergo apoptosis.

Various endothelial cells, with the exception of those from human microvasculatures, have been known to resist Shiga toxins (Stxs) in vitro. However, freshly prepared primary cultures of human endothelial cells from the umbilical vein and artery and the saphenous vein were shown to be killed by a very low dose of Stxs. This cytotoxicity of Stxs involves apoptosis, which seems to be caused by a mechanism distinct from the well-known action of Stxs to inhibit protein synthesis, since the blockade of protein synthesis by cycloheximide could not induce apoptosis or enhance the effect of Stxs. Passaged human endothelial cells have been found to be highly resistant to Stxs, which is consistent with previous reports, and not to show any evidence of apoptosis even when they are killed by a high dose of Stxs.

Apoptosis↗

67Ga whole-body scintigraphy in the evaluation of head and neck squamous cell carcinoma.

The diagnostic accuracy of 67Ga-citrate whole-body scintigraphy for the evaluation of primary tumours, local recurrences, cervical node metastases and distant metastases was investigated in patients with head and neck squamous cell carcinoma (SCC). Altogether, 102 67Ga-citrate whole-body scans were performed on 83 patients with head and neck SCC using a dual-headed gamma camera. The results were compared with those of computed tomography (CT) and final diagnosis. 67Ga scintigraphy correctly diagnosed 28 of 29 primary lesions, a sensitivity of 97% (CT = 97%). For tumour recurrence, 67Ga scintigraphy correctly diagnosed 13 of 15 recurrences and 53 of 58 instances of no recurrence, giving a sensitivity of 87% and a specificity of 91% (CT = 80 and 62%, respectively). Scintigraphy correctly diagnosed 23 of 31 metastatic sides of the neck and all 173 negative sides of the neck, giving a sensitivity of 74% and a specificity of 100% (CT = 90 and 84%, respectively). Finally, scintigraphy correctly diagnosed all 12 distant metastases as well as 86 of 90 cases of no metastasis, resulting in a sensitivity of 100% and a specificity of 96%. Furthermore, in five patients, distant metastases were initially detected on 67Ga scintigraphy. In conclusion, 67Ga whole-body scintigraphy with a dual-headed camera resulted in a high sensitivity and specificity for the detection of primary lesions, recurrences and distant metastases of head and neck SCC. Although the sensitivity for detecting neck node metastases was relatively low, the specificity was high. Thus, 67Ga scintigraphy is an effective technique for the evaluation of head and neck SCC, especially tumour recurrence and distant metastases.

Adolescent↗

[Influence of dexamethasone on the clinical course of bacterial meningitis in children. Especially on secondary fever. Experiences in 27 institutions].

Of pediatric patients with purulent meningitis seen at the institutions listed in the title page of this paper between 1986 and 1994, 93 patients treated with antibiotics and dexamethasone (DXM) were compared with 91 patients treated with antibiotics alone. The patients receiving antibiotics with dexamethasone achieved overall improvement in inflammatory symptoms and signs and cerebrospinal fluid findings and became afebrile significantly earlier than those receiving antibiotics alone. However, some of the patients became febrile again. The secondary fever rate for the DXM group was much higher than that for the antibiotic alone group (p < 0.0001). In most of the rebounded cases, the body temperature rose above 38 degrees C and remained elevated for 2-4 days. Cerebrospinal fluid (CSF) was cultured daily in 54 and 32 patients receiving antibiotics with and without DXM, respectively. Although this study was not a controlled study in a strict sense, these patients compared. In both groups, the CSF became mostly culture-negative within 48 hours. In a few patients receiving DXM, however, it became culture-negative after 72 hours or longer. DXM caused an adverse effect in a patient with meningitis caused by Streptococcus pneumoniae. The adverse effect was mild gastrointestinal bleeding, which recovered spontaneously. From the findings described above, the use of DXM combined with antibiotic therapy was considered to accelerate the relief from fever and improvement of inflammatory symptoms and signs and CSF findings. The body temperature rose again in more than half of the patients receiving DXM, but fell to normal spontaneously without treatment. The elevation doubtlessly could not be distinguished from recurrence of the meningitis itself or complications. It seems to be likely that no treatment but careful observation is required even if the fever recurs as far as the CSF findings showed favorable progress with excelluent general conditions. When DXM is given, it is essential that CSF tests and culture are repeated during the early stages and the progress is monitored carefully.

Anti-Bacterial Agents↗

Streptococcal pyrogenic exotoxin F (SpeF) causes permeabilization of lung blood vessels.

Acute respiration distress syndrome (ARDS) is a typical complication in toxic shock-like syndrome (TSLS) caused by Streptococcus pyogenes. An isolated perfused rat lung model was used to identify the causative agent of ARDS in TSLS in this study. Some crude preparations separated from the culture supernatants of S. pyogenes isolates caused rapid increases in the weight of perfused lungs, indicating vascular permeabilization. Six samples from M type 1 and 3 isolates from TSLS and pharyngitis patients showed strong permeabilization activity, whereas preparations from isolates of other M types (although the number of isolates examined was limited) were negative. The active substance was purified to a single band by sodium dodecyl sulfate-polyacrylamide gel electrophoresis using various columns, and the N-terminal amino acid sequence was determined. The resultant sequence of eight amino acids was identical to SpeF (mitogenic factor). Moreover, the vascular permeabilization activity of the purified band was abolished with anti-SpeF antiserum prepared by immunizing with the purified SpeF. This activity was also neutralized by the antiserum prepared by immunizing with a synthetic peptide derived from the published SpeF sequence. These results suggested that streptococcal SpeF is a major cause of permeabilization of lung blood vessels and sufficient for the pathogenesis of ARDS under the conditions of TSLS caused by S. pyogenes.

Animals↗