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S Tanada

Publications and source records attributed to S Tanada.

At least 91 records · Page 5Linked to original sources
PubMed1995

[A time-saving approach for quantifying regional cerebral blood flow and application to split-dose method with 123I-IMP SPECT using a single-head rotating gamma-camera].

We have proposed a modified early method, which can shorten the total time required for the quantitative regional cerebral blood flow (rCBF) measurement with N-isopropyl-p(-)[123I]iodoamphetamine (123I-IMP) using single-head rotating gamma-camera and the continuous arterial sampling method. Between 7 to 25 minutes after the intravenous injection of 123I-IMP, brain activity increases linearly, the SPECT data acquisition is being performed, and during which detector is rotating continuously. Then the rCBF values based on the microsphere model were calculated using the planar images obtained before and after the above acquisition and 5 min after the injection, and input counts obtained by the continuous arterial sampling. A good correlation (r = 0.951) was observed between the rCBF values obtained by this method and the traditional method, in which the SPECT data acquisition started about 30 min after injection. Applying this method to the quantitative rCBF measurements at rest and during stress with Diamox by the split dose method of 123I-IMP, we could evaluate the rCBF at rest and cerebral perfusion reserve in the same day. We conclude that this method can shorten the total time required for the standard normal microsphere method and can be applied to the split dose method, and this method provide the rCBF values not so much affected by washout of the tracer from the brain.

Acetazolamide↗
PubMed1994

Comparison of [11C]diprenorphine and [11C]carfentanil in vivo binding to opiate receptors in man using a dual detector system.

A simple dual detector coincidence system was used to measure the binding of [11C]carfentanil and [11C]diprenorphine to opiate receptors in normal volunteers before and after the administration of naloxone. Total radioactivity without naloxone and the ratio of total/non-specific radioactivity was 2 times greater for [11C]diprenorphine than [11C]carfentanil. The dose of naloxone required to maximally block specific [11C]diprenorphine binding was 10 times that for [11C]carfentanil, indicating that [11C]diprenorphine labels opiate receptor subtypes in addition to mu opiate receptors.

Analgesics, Opioid↗
PubMed1994

An evaluation of the accelerated expectation maximization algorithms for single-photon emission tomography image reconstruction.

We previously reported that brain single-photon emission tomography (SPET) images could be improved by using an attenuation coefficient map constructed with transmission data and the iterative expectation maximization (EM) algorithm. However, the conventional EM algorithm (CEM) typically requires 30-80 iterations to provide acceptable results, limiting its clinical applicability. Several methods have been proposed to accelerate the EM algorithm. The purpose of this study was to search for a practical method for accelerating the EM algorithm. The methods investigated here include the accelerated EM algorithm (ACEM) using additive correction, ACEM using multiplicative correction, and Tanaka's filtered iterative reconstruction method (FIR). These methods were assessed by simulated SPET studies of a phantom incorporating nonuniform attenuation and by reference to clinical brain SPET data. In the simulation studies, the above methods were evaluated by using three parameters (root mean square error, log likelihood value, and contrast recovery coefficient); the results showed that FIR had an advantage over other methods in terms of all parameters. The results obtained using the clinical data demonstrated that FIR could reconstruct acceptable images in only five iterations. These results show that FIR offers significant advantages over CEM or other ACEMs, indicating that FIR can make the EM algorithm practical for clinical use in SPET.

Adult↗
PubMed1994

Evaluation of serum lactate dehydrogenase activity for estimation of energy expenditure in human subjects.

We investigated the relationship between serum lactate dehydrogenase (LDH) activity and energy expenditure in young adults, evaluating their serum LDH activities in order to develop an index of energy expenditure. The results obtained were as follows. (1) There were significant correlations between the serum LDH activity and energy expenditure/day, energy expenditure/body weight/day and daily activity index in men. (2) There were significant correlations between the serum LDH activity and energy expenditure/day and daily activity index in women. (3) A group of men who 'rarely' exercised had lower levels of serum LDH activity than those who exercised 'sometimes' or 'usually', but little difference was noted between similar groups of women.

Adult↗
PubMed1994

Recovery period from ureteral obstructions of different duration and severity in the rat kidney.

The relationship between the period for recovery from hydronephrosis and the characteristics of the obstruction still needs to be clarified. In rat kidney the left ureter was completely obstructed for 3, 7, 14 and 21 d and the renal function was measured by renal scintigraphy using 99mTC-dimercaptosuccinic acid 3, 7 and 14 d after the obstruction was removed. In addition, recovery from unilateral partial obstruction (PO) of different degrees of severity for 7 d was examined. The kidneys with very mild PO recovered within 3 d and those with a very long period of complete obstruction (CO) did not exhibit any significant recovery. However, most of the kidneys with CO of various durations and those with 7 days PO of various degrees of severity exhibited maximum recovery 7 d after the release of the obstruction. This study suggests that the period required for maximum recovery from hydronephrosis is usually constant, unless the obstruction is too mild to cause any damage or too long to permit any recovery.

Animals↗
PubMed1994

A study of embolizing materials for chemo-embolization therapy of hepatocellular carcinoma: effects of particle size and dose on chitin-containing cis-diamminedichloroplatinum(II) albumin microsphere antitumor activity in VX2 hepatic tumor model rabbits.

We prepared chitin-containing cis-diamminedichloroplatinum(II) (CDDP) albumin microspheres with various particle sizes, and investigated in vitro CDDP release; the antitumor effect towards VX2 tumor introduced into rabbits was then examined. It was found that the rate of release of CDDP from chitin-containing CDDP albumin microspheres in vitro was increased with reduced particle size. Administration of microspheres to VX2 tumor-bearing rabbits via the hepatic artery resulted in different profiles of plasma platinum concentration depending on the particle size, and a higher concentration of platinum was released from the beginning of administration as particle size was reduced. The platinum content in hepatic tissue following the administration of CDDP microspheres was increased as the particle size decreased, although the rate of increase was not uniform. The antitumor effect of CDDP assessed by the suppression of tumor growth tended to be higher when microspheres of smaller sizes were used. However, no significant difference was observed in tumor growth rate between rabbits injected with microspheres smaller than 20 microns and those injected with sizes between 20 and 37 microns (p > 0.05). We also examined the relationship between the CDDP dose and antitumor effect using microspheres of less than 20 microns and observed a dose-dependent antitumor effect. No significant difference was observed, however, between 2 and 4 mg eq CDDP/kg dose levels (p > 0.05). From these results, we concluded that microsphere size and CDDP dose were strongly correlated with the augmentation of antitumor effect of chitin-containing CDDP albumin microspheres used in chemo-embolization therapy via the hepatic artery.

Albumins↗
PubMed1994

[The evaluation of the newly produced assay kit for the cytokeratin fragment, "ball ELSA CYFRA21-1"].

We evaluated the newly produced tumor marker assay kit, "Ball ELSA CYFRA21-1", which detects cytokeratin 19 fragment in the sera of patients with malignancies, especially lung cancers. The assay procedure is simple based on the one-step radioimmunometric assay method. The measured values depend somewhat on incubation temperature and time. Reproducibility and recovery were good. The minimum measurable level was 1 ng/ml. The dilution test was satisfactory. The CYFRA21-1 levels were gradually decreased by repeated freezing and thawing and after seven such exercises its activity dropped to about 70% of that of first assay. The presence of CYFRA21-1 antigen was strongly correlated with TPA antigen and, although some discrepancies could be observed in clinical samples, CYFRA21-1 activity was completely absorbed by anti-TPA antibody-coated beads in one sample. CYFRA21-1 levels of 44 normal controls were below 1.0 ng/ml. Assuming a cut-off value of 2.0 mg/ml, 32.7% of all cases with benign disease had values greater than 2.0 ng/ml. This fell to 21.4% on exclusion of cases of interstitial pulmonary disease. Those with malignant diseases had high CYFRA21-1 levels whether associated with lung cancer or not. The most high positive ratios were observed in squamous cell lung cancer, small cell lung cancer, and uterine cervical cancer. In conclusion, CYFRA21-1 may be a good tumor marker comparable to TPA not only for lung cancer but also other malignancies as well. High false positives for lung cancer, however, were observed in other pulmonary diseases.

Adolescent↗
PubMed1994

[Assessment of myocardial viability by thallium-201 reinjection imaging with sublingual nitroglycerin].

Although thallium-201 (201Tl) reinjection imaging improves the detection of myocardial viability compared to standard 3-4-hr redistribution (RD) imaging, it still underestimates the extent of viable myocardium. We examined whether 201Tl reinjection SPECT with sublingual nitroglycerin (NTG) had a higher sensitivity for viability detection than reinjection alone. Eighty patients with coronary artery disease were studied, 38 of them with an old myocardial infarction. At the peak of exercise, 111 MBq 201Tl was injected and the initial and the delayed SPECT images were obtained. Then, all patients were divided randomly into two groups, and in each group, SPECT data were obtained again after the injection of 37 MBq 201Tl with (NTG(+) group) or without 0.6 mg of sublingual NTG (NTG(-) group). Among 50 segments showing fixed defects on the delayed image in the NTG(+) group, 21 (42%) were found to be reversible on the reinjection image, as compared to 16 of 51 (31%) in the NTG(-) group. Twenty-two of 44 (50%) segments showing incomplete RD were found to be reversible in the NTG(+) group, while 17 of 42 (41%) segments in the NTG(-) group. Moreover, the ratio of reversible segments seen in the reinjection images was significantly higher in the collateralized regions of the NTG(+) group than in those of the NTG(-) group (20/26 vs. 14/28, p < 0.05). Thus, 201Tl reinjection SPECT with sublingual NTG improves the detection of ischemic but viable myocardium as compared to SPECT with reinjection alone.

Administration, Sublingual↗
PubMed1994

Studies on in vitro paraquat and diquat removal by activated carbon.

The adsorption characteristics of paraquat and diquat onto activated carbon in vitro were discussed for the primary treatment of acute poisoning by accidental, suicidal or homicidal ingestion of paraquat containing herbicides. Paraquat was adsorbed onto activated carbon more abundantly and more rapidly in physiological saline solution than that in artificial gastric juice and distilled water. Most suitable solvent for paraquat removal by activated carbon was physiological saline solution (0.9% sodium chloride solution). No significant correlation was observed between the ability of paraquat removal and the properties of adsorbent. Paraquat was preferentially adsorbed onto activated carbon in the mixed solution. The adsorption abilities by activated carbon (the removal ratio, the amount adsorbed and the adsorption rate) for paraquat were larger than those for diquat, and it was enhanced by added sodium chloride and added magnesium sulfate. Enhancing effect for adsorption removal was proportional to the saline concentration. As addition of salts into carbon suspension enhanced the adsorption ability, it will contribute to the effective treatment of acute poisoning.

Adsorption↗
PubMed1994

Thallium-201/technetium-99m-phytate (colloid) subtraction imaging of hepatocellular carcinoma.

UNLABELLED: This paper evaluates the clinical usefulness of 201Tl to image hepatocellular carcinoma (HCC), using 201Tl, 99mTc-phytate (colloid) and a three-headed SPECT camera. METHODS: The tumor-to-nontumor ratios (T/N) of 201Tl for different categories of HCC were generated. Tumors were emphasized by image subtraction (201Tl-99mTc-colloid). Thirty-three lesions in 16 patients (18 studies) with HCC were evaluated. There were 19 untreated nodular, five untreated diffuse, five local recurrent and four necrotic lesions after interventional therapy. RESULTS: The mean T/N were as follows: untreated nodular 1.54 +/- 0.31 (mean +/- s.d.), untreated diffuse 1.28 +/- 0.26, local recurrence 1.50 +/- 0.29 and necrosis 0.22 +/- 0.06. All the tumors (except necrotic areas) were enhanced by the image subtraction. CONCLUSION: Thallium-201 is useful for liver tumor imaging but 99mTc-phytate (colloid) is essential to discriminate 201Tl tumor uptake from normal liver accumulation. Image subtraction (201Tl/99mTc-colloid) is helpful in detecting HCC.

Aged↗
PubMed1994

[A case of subacute stroke with high uptake of 99mTc-HMPAO in the reperfused infarct corresponding to low perfusion area].

We reported a case of subacute stroke which showed high uptake of 99mTc-d,l-hexamethylpropyleneamine oxime (HMPAO) in the reperfused infarct corresponding to slightly decreased perfusion by 133Xe inhalation CBF measurement. In the chronic stage, both SPECT images of 99mTc-HMPAO and 133Xe showed low perfusion in the affected lesion. It was, therefore, considered that the high uptake of 99mTc-HMPAO had represented luxury perfusion. In the subacute stage of stroke, high uptake of 99mTc-HMPAO may imply luxury perfusion but not always hyperperfusion. It is suggested that the fractional fixation of 99mTc-HMPAO temporarily change in the affected lesion and it is essential to take into consideration the clinical stage for the interpretation of SPECT images.

Acute Disease↗
PubMed1993

Improvement of brain single photon emission tomography (SPET) using transmission data acquisition in a four-head SPET scanner.

Attenuation coefficient maps (mu-maps) are a useful way to compensate for non-uniform attenuation when performing single photon emission tomography (SPET). A new method was developed to record single photon transmission data and a mu-map for the brain was produced using a four-head SPET scanner. Transmission data were acquired by a gamma camera opposite to a flood radioactive source attached to one of four gamma cameras in the four-head SPET scanner. Attenuation correction was performed using the iterative expectation maximization algorithm and the mu-map. Phantom studies demonstrated that this method could reconstruct the distribution of radioactivity more accurately than conventional methods, even for a severely non-uniform mu-map, and could improve the quality of SPET images. Clinical application to technetium-99m hexamethyl-propylene amine oxime (HMPAO) brain SPET also demonstrated the usefulness of this method. Thus, this method appears to be promising for improvement in the image quality and quantitative accuracy of brain SPET.

Adult↗
PubMed1993

A study of embolizing materials for chemo-embolization therapy of hepatocellular carcinoma: effects of chitin concentration on cis-diamminedichloroplatinum(II) albumin microsphere properties and antitumor effect in VX2 hepatocellular carcinoma model rabbits.

cis-Diamminedichloroplatinum(II) (CDDP) albumin microspheres were prepared with various chitin concentrations and microsphere CDDP contents, specific surface area, surface structure and other microsphere properties. CDDP release in vitro and the antitumor effect in VX2 tumor model rabbits were investigated. CDDP content was increased as the concentration of chitin increased; at a chitin concentration of 6.0% it was about 2 times that without chitin. Specific surface area also increased with chitin concentration. CDDP release rate from various microspheres in vitro was suppressed as chitin concentration increased. Thus, microsphere properties, especially surface structure, are affected by an increase in chitin concentration. In experiments in vivo, various microspheres were injected into the hepatic artery of VX2 hepatocellular carcinoma model rabbits, and the effects of the chitin concentration on the time course of blood platinum (Pt) level and the antitumor effect were assessed. The blood Pt concentration increased with increase in chitin concentration, with a maximum of 0.45 microgram/ml at a concentration of 6.0%, even 7 d following microsphere administration. Tumor growth was suppressed when the chitin concentration was increased. Tissue Pt concentrations also increased in the presence of chitin. These findings suggest that increasing the chitin concentration might promote microsphere decomposition and hence CDDP release in vivo, thus improving immunopotentiating activity and resulting in enhanced CDDP antitumor effect. The detailed mechanisms of the action, however remains to be studied.

Albumins↗
PubMed1993

A study of cis-diamminedichloroplatinum(II) suppositories for the treatment of rabbit uterine endometrial carcinoma.

cis-Diamminedichloroplatinum (II) (cisplatin: CDDP) suppositories containing NaCl at different concentrations were prepared as a local chemotherapeutic agent for the treatment of uterine endometrial carcinoma and were administered to rabbits implanted with uterine VX2 tumor. The intrauterine CDDP histological level, as well as the antitumor effects and side effects of the suppositories to the liver and kidney were studied. The results showed high intrauterine tissue CDDP level in all suppository administrations. In particular, the NaCl-added suppositories enhanced the intrauterine CDDP level. As for antitumor effects, while the tumor growth rate of the NaCl-added suppository group was likely to be suppressed, the suppositories could not suppress tumor growth completely. The plasma platinum (Pt) level was 1.5 micrograms/ml or less and that of the liver and kidney was as low as 0.31 to 0.48 micrograms/g. No difference in levels depending on NaCl concentration was observed, nor was any abnormality found in the biochemical analysis including glutamate oxaloacetate transaminase (GOT) and blood urea nitrogen (BUN). Histopathological study revealed the degeneration of tumor cells in the NaCl-added suppository group. Minimal congestion and hemorrhage were observed in the endometria, possibly resulting from CDDP. By adding NaCl to CDDP suppositories, the uterine CDDP level and antitumor effects increased while no serious renal dysfunction was noted. Therefore, we conclude that NaCl-added CDDP suppositories are a useful local chemotherapy for endometrial carcinoma.

Animals↗
PubMed1993

[In vitro adsorption of paraquat onto substituted chitosan beads].

Paraquat removal by chitosan with different substituents was investigated in vitro for evaluation of chitosan as a paraquat adsorbent in emergency treatment for acute paraquat poisoning. Chitosan CM and SU, in which the hydroxyl group at the C6 position is replaced by a carboxymethyl and sulfonic group, respectively, removed paraquat abundantly in purified water. However an inhibitory effect of sodium chloride on paraquat removal by CM and SU was recognized. On the other hand, paraquat removal by cross-linked chitosan (BCW) was accelerated in saline solutions. It was recognized that more paraquat was removed by BCW chitosan when the sodium chloride concentration was less than 1.8%. It was confirmed that some chitosan beads (CM and SU) could function as effective paraquat adsorbents through in vitro experiments.

Adsorption↗
PubMed1993

Evaluation of exercise intensity indicated by serum lactate dehydrogenase activity in healthy adults.

Noting relationship between exercise and serum LDH and alpha-HBD activities, we prescribed 3 exercise regimens of various intensities for 22 healthy adult subjects over predetermined periods. Variations in the serum enzyme activities were determined in relation to these exercise programs. We studied whether these enzyme levels may serve as new indices to evaluate the amount of exercise. The test subjects were divided into 3 groups to perform 3 types of exercise (30%, 50%, 70% of VO2max) for 6 weeks. The serum enzyme activities at the start and completion of the experiment were determined and compared. The results obtained were as follows: A rise in the serum LDH activity was noted in association with exercise. The mean increases for these groups were 10.2%, 7.5% and 23.5%. A statistically significant decrease in the serum alpha-HBD activity was noted in association with exercise. It has been suggested that by observing variations in these enzyme levels in normal individuals for an extended period, change in the intensity of physical exertion within the range of daily activities can be estimated.

Adult↗