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Biomedical subjects

Y Ishimaru

Publications and source records attributed to Y Ishimaru.

At least 37 records · Page 2Linked to original sources
PubMed1998

Targeted cancer chemotherapy for VX2 tumour implanted in the colon with lipiodol as a carrier.

In this study, we examined the possibility of targeting drug delivery to tumours by dissolving the cytotoxic drug in a lipid fluid that is selectively deposited in tumours. Rabbits bearing VX2 tumour 10-20 mm in diameter in the large bowel received arterial injections of 0.2 ml of mitomycin C (MMC) dissolved in Lipiodol (MMC/Lipiodol), and the antitumour activity and adverse effects were examined. One week after treatment complete necrosis of the tumour was observed in 8 of 10 rabbits that received MMC/Lipiodol (3 mg/ml) without severe adverse effects on the surrounding caecum. In comparison 3/12 control animals that received MMC in saline and Lipiodol also showed complete necrosis. 6 of 7 rabbits killed eight weeks after the injection of MMC/Lipiodol were cured, with no viable tumour cells and with a normal appearance of the surrounding large bowel. In conclusion, MMC dissolved in Lipiodol may be adaptable for the treatment of colon cancer and may achieve antitumour activity without severe adverse effects.

Animals↗
PubMed1998

A method for estimating the integral of the input function for the quantification of cerebral blood flow with 123I-IMP using one-point arterial blood sampling.

We have developed a new method to replace the conventional method of quantitatively measuring cerebral blood flow (CBF), in which octanol-extracted radioactivity counts are measured in continuous arterial blood samples. With the new method, the whole-brain time-activity curves early after the intravenous injection of N-isopropyl-p-[123I]iodoamphetamine were first obtained by the least-squares curve-fitting method. The equation thus obtained was differentiated and the radioactivity counts were corrected by the 5-min octanol-extracted radioactivity counts of the arterial blood sample obtained at a single time point. In the present study, the value obtained by integrating the equation from 0 to 5 min, which was obtained by curve-fitting, was compared with the octanol-extracted radioactivity counts obtained by 5-min continuous arterial blood sampling in 160 patients with cerebrovascular disorders. The results showed good agreement between the values obtained by the two procedures (y = 1.049x - 1522.4; r = 0.987). Using the CBF obtained by the 5-min continuous arterial blood sampling as the standard, the errors using the present integral values of the input function were 7.1 +/- 4.9%. Measurements of the integral of the input function by the present one-point arterial blood sampling method has the potential for use in the routine measurement of CBF, because it is less invasive and more convenient than the conventional method, and it is unaffected by cardiopulmonary disease or smoking.

Arteries↗
PubMed1998

Correlation of wing-leg identity in ectopic FGF-induced chimeric limbs with the differential expression of chick Tbx5 and Tbx4.

It has been reported that members of the fibroblast growth factor (FGF) family can induce additional limb formation in the flank of chick embryos. The phenotype of the ectopic limb depends on the somite level at which it forms: limbs in the anterior flank resemble wings, whereas those in the posterior flank resemble legs. Ectopic limbs located in the mid-flank appear chimeric, possessing characteristics of both wings and legs; feather buds are present in the anterior halves with scales and claws in the posterior halves. To study the mechanisms underlying the chimerism of these additional limbs, we cloned chick Tbx5 and Tbx4 to use as forelimb and hindlimb markers and examined their expression patterns in FGF-induced limb buds. We found that Tbx5 and Tbx4 were differentially expressed in the anterior and posterior halves of additional limb buds in the mid-flank, respectively, consistent with the chimeric patterns of the integument. A boundary of Tbx5/Tbx4 exists in all ectopic limbs, indicating that the additional limbs are essentially chimeric, although the degree of chimerism is dependent on the position. The boundary of Tbx5/Tbx4 expression is not fixed at a specific position within the interlimb region, but dependent upon where FGF was applied. Since the ectopic expression patterns of Tbx5/Tbx4 in the additional limbs are closely correlated with the patterns of their chimeric phenotypes, it is likely that Tbx5 and Tbx4 expression in the limb bud is involved in determination of the forelimb and hindlimb identities, respectively, in vertebrates.

Amino Acid Sequence↗
PubMed1998

[Estimation of integral value of input function for the quantification of cerebral blood flow with 123I-IMP using one-point arterial blood sampling].

Cerebral blood flow (CBF) has been measured using a microsphere model with octanol-extracted radioactivity counts (integral value of input function). We developed a new method estimating the integral value of input function. First, we fitted the whole brain time-activity curves early after intravenous injection of N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) by the least-squares method. Second, we differentiated this equation. Third, we calibrated it using octanol-extracted radioactivity counts of the arterial blood sampled at 5 min. Finally, we integrated it. A significant correlation was found between the integral values obtained using a new method and those obtained using the continuous arterial blood sampling data (y = 1.048x-1206, r = 0.984). The errors between the CBF values obtained using a new method and those obtained using the 5-min continuous arterial blood sampling was 6.88 +/- 4.78%. Measurement of integral values of the input function using a new method with one-point arterial blood sampling is less invasive and convenient, and is not influenced by cardiopulmonary disease or smoking. Therefore, it would be useful for the routine measurement of CBF.

Amphetamines↗
PubMed1998

[Simplified method to quantitate regional cerebral blood flow by 123I-IMP microsphere model: validity of input counts by using the whole brain time-activity curve and one point arterial blood sampling].

We developed a new microsphere method using 123I-IMP in which arterial blood is collected at one time point early after 123I-IMP injection instead of conventional continuous arterial blood sampling, and the input count is estimated using a whole brain time-activity curve until that time point. The differential curve dCb(t)/dt of the brain time-activity curve Cb(t) early after 123I-IMP injection (when the microsphere model is established) approximates the arterial time-activity curve Ca(t) as an input function. The input count as the integral value of Ca(t) at 0-5 min was estimated using the 50 min whole brain activity Cb(5 min) and the differential value dCb(5 min/dt and the 5-min octanol-extracted count of arterial samples obtained at one time point Ca(5 min). The input counts calculated by this method were very closely correlated with measurement values obtained by continuous arterial sampling. This method is more convenient and less invasive than the continuous arterial sampling method.

Amphetamines↗
PubMed1998

[Investigation on feasibility of using a gamma camera for the measurement of blood radioactivity].

The present study was undertaken to determine whether gamma cameras can be used to measure radioactivity in samples, e.g. in blood. Aqueous 123I solution with a concentration of 10.3 MBq/ml was infused at a volume of one ml into a blood-sampling vial having an internal diameter of 22.5 mm. Various concentrations of radioactivity were generated by leaving the vial and taking radioactive decay into account. Static images were acquired for five minutes with a gamma camera using a 64 x 64 matrix to measure radioactivity counts, and the regions of interest with 7 x 7 pixels (21 mm x 21 mm) were defined on the image. The results showed that there was a good linear correlation between the radioactivity counts measured with the gamma camera without collimator and those measured with the well-type scintillation counter in the range between 0.032 kBq/ml and 279 kBq/ml. It therefore appears that gamma cameras can be substituted for well-type scintillation counters in the measurement of radioactivities in samples.

Blood↗
PubMed1998

Measurement of blood radioactivity for quantification of cerebral blood flow using a gamma camera.

OBJECTIVE: This study was designed to determine whether gamma cameras can be substituted for well-type scintillation counters in measuring blood radioactivity counts to be used as an input function for the quantitative measurement of cerebral blood flow (CBF). METHODS: Twelve different aqueous 123I solutions were prepared by serial dilution of the original concentration of 281.9 kBq/ml, and the radioactivity count of each dilution was measured with a gamma camera with the collimator removed, and with a well-type scintillation counter. When measuring the radioactivity counts with a gamma camera, static images were acquired using a 128 x 128 matrix for 5 min, and the regions of interest with 14 x 14 pixels (21 mm x 21 mm) were defined. RESULTS: There was a good correlation between the results obtained by these two procedures in the range of concentration between 0.008 kBq/ml and 281.9 kBq/ml (y = 4.245x-2.549, r = 1.0, n = 12, s.e.e. = 7.217 kcpm). There was good agreement between the CBF values (ml/100 g/min) obtained using the cross-calibration factor (CCF) and blood radioactivity counts measured with the two procedures (y = 0.990x + 0.552, r = 0.990, n = 231, s.e.e. = 1.340 ml/100 g/min). CONCLUSION: The results suggest that gamma cameras can be substituted for well-type scintillation counters in the quantitative measurement of CBF, and make it unnecessary to measure CCF after routine calibration of a SPECT apparatus.

Brain↗
PubMed1997

Intracranial intraparenchymal schwannoma: report of three cases.

Intracranial intraparenchymal schwannomas are rare. We report three patients with an intracranial intraparenchymal schwannoma and discuss the clinical and neuroradiological aspects of this particular tumour. The patients were a 21-year-old male, a 64-year-old female and a 17-year-old male. The tumours were located in cerebrum in two patients and the cerebellum in one patient. Computerized tomography (CT) scans demonstrated a slightly high density area with homogeneous enhancement by contrast medium. Magnetic resonance imaging (MRI) showed slightly low signal intensity on the T1-weighted image, high or mixed signal intensity on the T2-weighted image and homogeneous enhancement by gadolinium diethylene triamine penta-acetic acid (Gd-DTPA). Radiological studies revealed cystic components in 2 of the 3 patients. All tumours were firm, well-demarcated, and completely removed. The diagnosis of schwannoma was derived from histological and immunohistochemical studies in all 3 cases; 2 cases were also examined by electron microscopy.

Adolescent↗
PubMed1997

The mesenchymal factor, FGF10, initiates and maintains the outgrowth of the chick limb bud through interaction with FGF8, an apical ectodermal factor.

Vertebrate limb formation has been known to be initiated by a factor(s) secreted from the lateral plate mesoderm. In this report, we provide evidence that a member of the fibroblast growth factor (FGF) family, FGF10, emanates from the prospective limb mesoderm to serve as an endogenous initiator for limb bud formation. Fgf10 expression in the prospective limb mesenchyme precedes Fgf8 expression in the nascent apical ectoderm. Ectopic application of FGF10 to the chick embryonic flank can induce Fgf8 expression in the adjacent ectoderm, resulting in the formation of an additional complete limb. Expression of Fgf10 persists in the mesenchyme of the established limb bud and appears to interact with Fgf8 in the apical ectoderm and Sonic hedgehog in the zone of polarizing activity. These results suggest that FGF10 is a key mesenchymal factor involved in the initial budding as well as the continuous outgrowth of vertebrate limbs.

Amino Acid Sequence↗
PubMed1997

[Compton-scatter correction using the triple energy window (TEW) method in conventional single photon emission computed tomography without TEW acquisition hardware].

We devised a method which allowed the triple energy window (TEW) method to be applied for Compton-scatter correction in conventional single photon emission computed tomography (SPECT) systems without any hardware for TEW acquisition. In this method, the data within two subwindows located at both sides of the main window were acquired together. The effectiveness of this method was investigated by phantom experiments. The integral and differential uniformities measured using a flood phantom filled with 123I were minimized when the energy width of subwindows was 5 keV (5.8% and 4.2%, respectively). When this method was applied to a brain phantom filled with 123I in which the relative activities in white and gray matter were assigned as 1: 4.3, the ratio of SPECT values between them was more accurate (1:4.26) than that obtained without this method (1:208). This method appears to be useful for Compton-scatter correction in SPECT, because it can be applied to conventional SPECT systems without any hardware for TEW acquisition and is available for routine clinical use for its simplicity.

Brain↗
PubMed1996

Lingual carcinoma. Correlation of MR imaging with histopathological findings.

PURPOSE: To determine the utility of MR imaging in the evaluation of lingual carcinomas. MATERIAL AND METHODS: Eleven patients with lingual carcinoma were evaluated with MR imaging including dynamic study within one week before surgery. Nine patients underwent preoperative chemotherapy or irradiation, and 2 patients had no preoperative treatment. Delineation of the tumor, the contrast between tumor and surrounding tissue, and extent of the tumor were evaluated in a blinded manner. After glossectomy, MR images were correlated with pathological findings. Statistical analysis was performed on the visual assessment ratings. RESULTS: Blinded evaluation suggested that dynamic and T2-weighted images (T2WI) were significantly superior to postcontrast T1WI in demonstrating the lesion. There were no significant differences between dynamic MR images and T2WIs. However, histopathological correlation showed that in patients with preoperative treatment, dynamic MR imaging demonstrated more accurately the size and extent of the residual tumor than did T2WI and postcontrast T1WI, which tended to demonstrate an area of signal abnormality that was more extensive than the true size of the residual lesion. In patients without preoperative treatment, dynamic MR imaging, T2WI, and postcontrast T1WI gave an equivalent depiction of the extent of the carcinoma. CONCLUSION: In patients with no preoperative treatment, dynamic MR imaging does not appear to offer any advantage over T2WI. However, in patients with preoperative treatment, dynamic MR imaging provides a more accurate assessment of the residual tumor than do T2WI and postcontrast T1WI.

Aged↗
PubMed1995

Dermatoglyphic (fingerprint) pattern in biliary atresia.

The dermatoglyphic (fingerprint) patterns of 288 patients with biliary atresia (117 males and 171 females) were compared to those of normal Japanese. Arches and radial loops were seen more frequently than the normal distribution on thumb, ring- and little-fingers. Nineteen percent of the patients had abnormal fingerprint patterns.

Biliary Atresia↗
PubMed1995

[Epidemiological studies on enteric adenovirus gastroenteritis in children].

Enteric adenoviruses (EAd), adenovirus (Ad) types 40 and 41, have been established as causative agents of gastroenteritis. By electron microscopic (EM) survey of acute gastroenteritis in children in the Matsuyama area, Ad were detected in 275 of 6476 fecal samples obtained from 1980 to 1993. Two-hundred-thirteen Ad-positive samples were tested for serotyping by the enzyme-linked immunosorbent assay (ELISA) using three monoclonal antibodies, Ad group-specific, Ad 40 type-specific and Ad41 type-specific antibody. Of 199 samples serotyped by ELISA, 65 were identified as Ad40, 73 as Ad41, 1 as double infection with Ad40 and Ad41, and 60 as Non-EAd. About 70% of Adenovirus detected by EM were suggested to be EAd. Other epidemiological feature was as follows: EAd were detected throughout the year. The predominant serotype was Ad40 during 1980-1985, while Ad41 were observed after 1986. EAd were detected most frequently from the children aged 0-3 years. The incidence of fever in EAd positive group was lower (30%) than that (67%) in the Non-EAd positive group. The incidence of vomiting, nausea and respiratory symptoms was higher in Ad41 associated infections than Ad40.

Adenoviridae↗
PubMed1993

A monoclonal antibody disrupting cell-cell adhesion of rat ascites hepatoma cells.

A cell surface-associated adhesive factor (AF) separated from differentiated rat ascites hepatoma AH136B cells (forming cell islands in vivo) has been highly purified by chromatography. AF is assumed to mediate the cell-cell adhesion essential to island formation of the hepatoma cells. A substance, immunologically cross-reactive with AF, is present in the ascites fluid or culture medium of the AH136B cells. Because the substance is almost identical to AF in molecular weight and aggregation-promoting activity, it has been concluded that AF is released into the ascites fluid where it is concentrated. Monoclonal antibodies have been raised against AF purified from ascites fluid of AH136B cells. We have obtained a monoclonal antibody, coded MoAF-6D6, that strongly abolishes the aggregation-promoting activity of AF. When AH136B cell islands are incubated in the presence of Fab fragments of MoAF-6D6, cell detachment from the islands is evident within 24 h. Cell islands following 36-h culture show a distinct dissociation and islands completely lose their organization 48 h after culture. The dissociating effect of MoAF-6D6 is neutralized by the addition of AF. These results suggest that AF plays a significant role in the maintenance of cell islands.

Animals↗
PubMed1993

Three familial cases of fundic gland polyposis without polyposis coli.

We report three cases of fundic gland polyposis in the stomach identified in three patients who were related. Grossly the numerous polyps covered an area limited to the body and fundus of the stomach, no polyps were found in the antrum, duodenum, colon, or rectum, and histologically, the gastric lesions consisted of numerous hamartomatous polyps, characterized by proliferation of the fundic and cystic glands. The gastric lesions were identified in families without polyposis coli. This type of fundic gland polyposis has never been documented before in the literature.

Adolescent↗
PubMed1993

Protective effects of cyclodextrin sulphates against gentamicin-induced nephrotoxicity in the rat.

The effects of cyclodextrin sulphates on the development of rat renal dysfunction induced with gentamicin, an aminoglycoside antibiotic, were studied. Daily subcutaneous injection of gentamicin (100 mg kg-1, 14 days) developed nephrotoxicity in the rat as assessed by an increase in serum urea nitrogen and histopathological changes in the renal cortex. When cyclodextrin sulphates were given intraperitoneally at 300 mg kg-1 at 6 h intervals after gentamicin administration, they protected the rat against the drug-induced renal impairment, while the parent cyclodextrins were ineffective. Since post-administration of cyclodextrin sulphates did not reduce the total amount of gentamicin accumulated in the kidney, the protection may occur through interference with intracellular events leading from the drug accumulation to nephrotoxicity. These results suggest that cyclodextrin sulphates are particularly effective in preventing renal failure associated with aminoglycoside treatment.

Animals↗