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Biomedical subjects

N Akagi

Publications and source records attributed to N Akagi.

At least 19 recordsLinked to original sources
PubMed1999

Scintigraphic prediction of resistance to radiation and chemotherapy in patients with lung carcinoma: technetium 99m-tetrofosmin and thallium-201 dual single photon emission computed tomography study.

BACKGROUND: Various prognostic markers for lung carcinoma have been proposed, but to the authors' knowledge none is noninvasive and convenient for clinical use. The current study examined the utility of several radiotracers for the prediction of multidrug resistance (MDR) and radioresistance in patients with lung carcinoma. METHODS: Thirty patients with untreated lung carcinoma underwent a dual isotope single photon emission computed tomography (SPECT) scan at 10 minutes and 120 minutes after the injection of technetium-99m ((99m)Tc)-tetrofosmin ((99m)Tc-TF) (370 megabecquerels [MBq]) and thallium-201 ((201)TlCl) (111 MBq). Retention of each tracer was evaluated semiquantitatively. Using radiation and chemotherapy (cisplatin plus etoposide), the patients either were treated sequentially (n = 12) or concurrently (n = 18). The relation between therapeutic response and retention of each tracer was analyzed. The detectability of radioresistance was examined. RESULTS: In patients treated with sequential therapy, the response to radiation was predicted by (99m)Tc-TF retention, whereas (201)Tl retention was found not to be predictive. Regardless of whether the sequential or concurrent protocol was applied, 14 of 18 tumors with high (99m)Tc-TF retention (>/= 15%) exhibited a favorable response to chemoradiotherapy whereas all 12 tumors with low (99m)Tc-TF retention (</= 15%) did not respond to the therapy. In contrast, (201)Tl retention was not found to be a predictive factor. CONCLUSIONS: The employed SPECT method is a useful tool for the in vivo prediction of radioresistance, P-glycoprotein (P-gp), and non-P-gp MDR in lung carcinoma. Low (99m)Tc-TF retention serves as a strong predictor of therapeutic resistance. High (99m)Tc-TF retention implies a favorable response. (201)Tl did not appear to be a predictive factor but is required for localization of the lesion on SPECT imaging.

Aged↗
PubMed1999

Extraosseous metastases of hepatocellular carcinoma detection and therapeutic assessment with Tc-99m PMT SPECT.

Owing to recent advances in imaging technology and radiologic intervention, survival rates in patients with hepatocellular carcinoma have improved markedly. However, such prolonged survival has resulted in an increase in extrahepatic metastases. Tc-99m (Sn)-N-pyridoxyl-5-methyltryptophan (Tc-99m PMT), developed for hepatobiliary scintigraphy, has been used to visualize extrahepatic metastases, with most related reports limited to osseous metastases. The authors report two cases of hepatocellular cancer presenting as a hypopharyngeal metastasis and intraperitoneal dissemination along the tract of a fine-needle biopsy. Lesions undetectable on planar imaging could be visualized by Tc-99m PMT SPECT.

Aged↗
PubMed1998

Dual-isotope SPECT diagnosis of a skull-base metastasis causing isolated unilateral hypoglossal nerve palsy.

We describe a 48-year-old female with an isolated unilateral hypoglossal nerve palsy caused by a skull base metastasis from breast cancer. The patient had a medical history of conservative breast therapy for breast cancer. Although the cause of such a neurological deficit includes various pathologies, the reports focusing on metastatic tumor have been limited in number. Radiologic investigation showed a mass involving both the right hypoglossal canal and the clival edge. Swelling of the hypoglossal nerve was observed in views including its canal. Three-dimensional CT images demonstrated the tumor protruding from the enlarged external orifice of the hypoglossal canal. In the present report we mentioned a nuclear medicine procedure to visualize and characterize the small, abnormal tissue in the skull base. Dual-isotope SPECT confirmed an abnormal uptake of 99mTc-HMDP around the hypoglossal canal and a 201Tl-positive elongated lesion running along the hypoglossal nerve.

Cranial Nerve Diseases↗
PubMed1998

Diagnosis of lung cancer using two-phase Tl-201 SPECT and modified retention image to view tumor in the collapsed lung: comparison with bolus CT.

In this report the usefulness of Tl-201 SPECT and modified retention images in the differentiation of lung cancer and postobstructive collapse was studied. Two-phase Tl-201 SPECT was performed in 20 lung cancer lesions in which postobstructive collapse was suspected on CT. Retention imaging was done afterward. Three types of Tl-201 images were compared with the bolus CT images. Bolus CT differentiated lung cancer from postobstructive collapse in 7 of the 20 lesions (35%). Tl-201 SPECT differentiated the two conditions in 9 of 20 lesions (45%) on early Tl-201 SPECT and in 13 of 20 lesions (65%) on delayed imaging. With modified retention images, differentiation was possible in 13 of 20 lesions (65%). By combining delayed Tl-201 SPECT and modified retention images, lung cancer alone could be demonstrated in 18 of 20 lesions (90%). Combined delayed Tl-201 SPECT and modified retention images were more effective than bolus CT in delineating the extent of lung cancer in the presence of postobstructive collapse.

Aged↗
PubMed1998

Relationship between ATP synthesis and 201Tl uptake in transformed and non-transformed cell lines.

201Tl tumour imaging is an established procedure, but little is known about its biological significance in transformed and non-transformed cells. In investigating the relationship between 201Tl uptake and intracellular ATP, we wished to determine whether the observed difference in delayed uptake is attributable to re-uptake via Na-K ATPase by using transformed (HeLa) and non-transformed (human fibroblast: hFB) cell lines. In each cell line, ATP was measured using the Luciferin-Luciferase method (LLM). The change in 201Tl uptake was assessed under conditions of mitochondrial suppression. Additionally, we assessed whether glycolysis is involved in 201Tl uptake under conditions of mitochondrial suppression and anaerobic incubation. Re-uptake via Na-K ATPase (HeLa vs hFB: 37.3 vs 24.2%) showed a clear difference in delayed uptake between HeLa and hFB. With HeLa, 201Tl uptake decreased biphasically with a reduction in ATP levels, whereas with hFB a linear correlation was evident. Despite the suppression of mitochondrial potential, a 5% glucose loading accelerated glycolysis with HeLa, and increased ATP (10.0 +/- 4.0%) and 201Tl uptake (16.2 +/- 3.0%). Conversely, neither ATP nor 201Tl uptake increased with hFB. Our results provide evidence that 201Tl uptake in transformed cells is related to enhanced glycolysis as well as mitochondrial ATP synthesis.

2,4-Dinitrophenol↗
PubMed1996

[Diagnosis of lung cancer using functional image of 201Tl SPECT with parameter of 201Tl retention--evaluation of its applicability to post irradiated lung cancer].

Thallium-201 (201Tl) SPECT is a useful method for detecting lung cancer. Moreover, the 201Tl Retention Index (R.I.) reported by Tonami et al is now available for differentiating pulmonary lung cancer from benign lesions. The diagnosis of recurrent tumors is, however, difficult to establish as they are often shaded by radiation pneumonitis or fibrosis. Therefore, we employed functional images (F.I.) obtained using as parameter a modified version of the R.I. First we indicated the statistical value of untreated solitary lung tumor as follows: sensitivity 84.6%, specificity 80.0%, and accuracy 83.3%. In our assessment, the lesions with tumor size over 2.0 cm and R.I. by Tonami et al over 12.7 were detected as positive images. Secondly in assessment of 22 cases (23 lesions) of post irradiated lung cancer, the results obtained were: sensitivity 80.0%, specificity 92.3%, and accuracy 87.0%. 201Tl SPECT functional images seem to be useful for the diagnosis of recurrent lung cancer by shaded radiation pneumonitis and fibrosis.

Adenocarcinoma↗
PubMed1995

Longer local retention of adoptively transferred T-LAK cells correlates with lesser adhesion molecule expression than NK-LAK cells.

The local retention of adoptively transferred lymphokine (IL-2)-activated killer (LAK) cells was examined in 11 patients with head and neck carcinoma. Unseparated lymphocytes, T and natural killer (NK) cells isolated from patients were cultured with IL-2 for 7 days, labelled with 99mTc-HMPAO, and immediately injected back into the respective donors via the superficial temporal artery or locally into the tumour tissue. The injected LAK cells were periodically traced using a gamma camera, and the LAK cell retention rate was calculated from the radioactivity. One hour after the injection, about 70% of the locally infiltrated LAK cells remained in the tumour tissue, while about half of the LAK cells transferred via the regional artery were dislodged from the tissue. LAK cells induced from T cells (T-LAK) were retained in the tissue for a longer time than LAK cells induced from NK cells (NK-LAK). T-LAK were less chemotactic and less adherent to human umbilical vein endothelial cells (EC), and showed lesser migration through EC. Flow cytometric analysis revealed higher expression of CD11a, CD11b, CD18 and CD49d on NK-LAK compared with T-LAK. MoAbs against these adhesion molecules suppressed adhesion and migration of LAK cells. These results indicate that the rapid disappearance of NK-LAK from the tissue is associated with their greater chemotactic and adhesive as well as migratory activities depending on differing expression of adhesion molecules.

Adult↗
PubMed1995

Determinants of exercise capacity in the hypertensive elderly--a study based on the assessment of cardiac reserve by dipyridamole radionuclide angiography.

To evaluate the determinants of exercise capacity in the hypertensive elderly with an assessment of cardiac reserve by dipyridamole radionuclide angiography, 31 elderly subjects (aged 62 to 78 years, 15 hypertensive and 16 normotensive) underwent symptom-limited maximum treadmill exercise with measurement of maximal oxygen consumption along with radionuclide angiography in list mode at rest and after dipyridamole infusion. In the normotensive elderly, maximal oxygen consumption correlated with relative filling volume during the rapid filling period at rest (r = 0.58; p < 0.05), and correlated inversely with the percent change in the peak ejection rate with dipyridamole (r = -0.63; p < 0.01). In contrast, maximal oxygen consumption correlated with atrial contribution at rest (r = 0.69; p < 0.005), and correlated inversely with the percent change in atrial contribution with dipyridamole (r = -0.87; p < 0.0001) in the hypertensive elderly. These results indicate that the mechanisms for maintaining exercise capacity are different in elderly subjects with or without hypertension.

Aged↗
PubMed1992

Microvessel and astroglial cell densities in the mouse hippocampus.

In order to study the factors responsible for glucose uptake in the mouse hippocampus, microvessel and astroglial cell densities were measured and compared in each laminal region. Microvessel density was examined on histologically prepared sections after injection of Indian ink and measured by means of an image analyser. Astroglial cell density was determined after the cells were stained immunohistochemically. Microvessel and astroglial cell densities were determined in 10 different hippocampal structures. Microvessel and astroglial cell densities were strongly correlated in all layers except the pyramidal cell layers. The highest density of perfused microvessels was found in the stratum lacunosum-moleculare, compared with other regions, and the lowest values were found in the stratum lucidum and dentate granular cell layer. Among pyramidal cell layers, microvessel density in sector CA3a was significantly higher than that in CA1.

Animals↗
PubMed1991

Free radical production by the red tide alga, Chattonella antiqua.

The red tide alga, Chattonella antiqua, was found to show a strong chemiluminescence, using luminol as the reagent, when exposed to ultraviolet irradiation. This luminescence was completely inhibited by ascorbate or catalase, suggesting that hydrogen peroxide was generated by the plankton. Red tide cells exposed to fish gill mucus from young yellowtail resulted in the release of a large number of mucocysts and a weak luminosity, and showed a strong reduction of cytochrome c in the medium. Therefore, the discharge of mucocysts from the red tide, induced by the presence of gill mucus, may be accompanied by the release of active oxygen species. The active oxygen may be involved in depolymerization of mucus glycoproteins from the gill lamellae.

Animals↗
PubMed1991

[Significance of diffuse slow washout in dipyridamole loading thallium-201 myocardial perfusion scintigraphy].

To assess the significance of diffuse slow washout (DSW) in dipyridamole loading thallium-201 myocardial perfusion scintigraphy, 382 patients were studied. DSW were observed in 69 (24%) of 285 patients with perfusion defects, 5 (5%) of 97 patients without perfusion defects. There was significant relation between DSW and perfusion defects (p less than 0.01). Coronary angiography showed multivessel disease in 84% single vessel disease in 12% of patients with DSW and multivessel disease in 28%, single vessel disease in 50% of patients without DSW. During a mean follow up period of 29 months, initial CABG or PTCA were done in 41%, cardiac death occurred in 12%, nonfatal cardiac events occurred in 7% of patients with DSW and perfusion defects. In patients without DSW, initial CABG or PTCA were done in 11%, cardiac death occurred in 7%, nonfatal cardiac events occurred in 5%. Patients without perfusion defects had good prognosis regardless of the presence or absence of DSW. In conclusion, DSW indicates serious cardiac ischemia in patients with perfusion defects. DSW does not indicate cardiac ischemia in patients without perfusion defects.

Aged↗
PubMed1989

[Clinical significance of negative dipyridamole perfusion scintigram].

Six hundred seventy-one patients who had dipyridamole perfusion scintigraphy were classified into two groups; ie, 242 patients without perfusion defect (Group A) and 429 patients with perfusion defect (Group B). Clinical significance of negative scintigram was then assessed and correlated with coronary angiographic findings and prevalence of cardiac events. 1) Significant coronary artery disease (greater than 50% luminar narrowing) was present in 7 of 92 patients (8%) in Group A and in 235 of 285 patients (82%) in Group B. Multi-vessel coronary artery disease was found only in 2 patients (2%) in Group A and in 119 patients (42%) in Group B. 2) During a mean follow-up period of 29 months, 48 cardiac death (8%) and 19 nonfatal cardiac events (3%) occurred in 619 medically treated patients. These cardiac complications were observed in 7 of 242 patients (3%) in Group A and in 60 of 377 patients (16%) in Group B, including 4 (2%) and 44 (12%) cardiac deaths, respectively. In conclusion, it is rare to see severe organic coronary artery disease and future cardiac event in patients with negative dipyridamole perfusion scintigram. It may be, therefore, stated that it is unnecessary to perform coronary angiography in these patients, unless they have symptoms which cannot be controlled medically.

Adolescent↗