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Biomedical subjects

K Torizuka

Publications and source records attributed to K Torizuka.

At least 73 records · Page 4Linked to original sources
PubMed1988

Evaluation by using radionuclide uptake of bone in Paget's disease of bone: special reference to treatment with calcitonin.

Bone scintigraphy using 99mTc-MDP was performed on 2 patients with Paget's disease of bone before and after the treatment with a synthetic eel calcitonin analogue [Asu1,7)-eel calcitonin, ECT] at a dose of 40 U per day. All pagetic lesions showed markedly the increased accumulation of the radionuclide. The uptake ratio, defined as the count rate of 99mTc-MDP over each bone lesion to that over the control bone, was calculated. The response to the calcitonin therapy was evaluated with the uptake ratio of the radionuclide. The uptake ratio decreased markedly within the first 3 months of the treatment, in association with a palliation of bone pain, while the serum alkaline phosphatase activities which had been within the normal range or slightly high before the treatment did not show any significant change or did not reflect a clinical feature (e.g. bone pain) with the treatment. Thus, the uptake ratio on the bone scintigram seemed to offer the most sensitive and most reliable information for the evaluation of calcitonin treatment of Paget's disease of bone.

Aged↗
PubMed1988

Clinical evaluation of tumour imaging using 99Tc(V)m dimercaptosuccinic acid, a new tumour-seeking agent.

Considering the favourable nuclear properties of 99Tcm over 67Ga, we have developed a new tumour-seeking agent, 99Tc(V)m dimercaptosuccinic acid (Tc(V)-DMSA). In order to evaluate the clinical usefulness of Tc(V)-DMSA scintigraphies, 492 patients were studied with Tc(V)-DMSA, and in some cases, where possible, the results were compared with conventional 67Ga citrate scintigraphies. There was a high degree of usefulness of Tc(V)-DMSA in patients with head and neck tumours, medullary thyroid carcinomas and soft tissue tumours. But in patients with carcinomas of the lung, liver and gastrointestinal tract, malignant melanoma and lymphoma, Tc(V)-DMSA was of no or little use.

Drug Evaluation↗
PubMed1987

[The role of nuclear medicine in endocrinology].

Radioisotopes have been widely used in both in vitro and in vivo studies of endocrine organs. In this lecture, results of our recent in vitro studies on calcium regulating hormones, thyroid-stimulating hormone, and gastro-intestinal hormones are reviewed. 1) Clinical evaluation of measurement of calcium regulating hormones such as PTH, calcitonin and vitamin D metabolites was demonstrated. Furthermore, problems of those assays were also discussed. Especially, simpler methods which measure intact PTH or vitamin D metabolites are to be developed. PTH-like factor, which should play the major role in hypercalcemia of malignancy, was assayed biologically. After determination of amino-acid sequence of this protein, clinical measurement should reveal mechanism of hypercalcemia of malignancy. 2) Studies on TSH-receptor antibodies by using radioreceptor assay. TSH-binding inhibitor immunoglobulins (TBII) were detected not only in 93% of untreated patients with Graves' disease, but also in 21% of patients with primary myxedema. In contrast to the thyroid-stimulating nature of TBII in Graves' patients, TBII in hypothyroid patients were disclosed to be blocking in their nature. Clinical and laboratory findings supported pathogenetic role of the blocking antibodies in the latter condition. 3) Mutual regulation between CCK and muscarinic receptors on dispersed pancreatic acini. CCK and carbachol in their higher concentrations regulated muscarinic receptor and CCK receptor, respectively. The mode of regulation of both receptors was disappearance of their high affinity binding site. TPA, an activator of protein kinase C, modulated both receptors in the same manner as CCK or carbachol. These effects of CCK and carbachol on receptors were well compatible to the restriction of carbachol or CCK induced amylase secretion by CCK or carbachol. These in vitro studies, in association with the results of in vivo studies, contribute to the developments of nuclear endocrinology.

Animals↗
PubMed1987

Recognition of ovarian cancer antigen CA125 by murine monoclonal antibody produced by immunization of lung cancer cells.

In studies aimed at developing monoclonal antibodies against lung adenocarcinomas, we produced a murine monoclonal antibody designated 130-22 by immunizing mice with lung cancer cells. Since in immunoperoxidase staining experiments this antibody was reactive not only with lung adenocarcinomas but also with ovarian carcinomas, we examined its relationship to the ovarian cancer marker CA125, an antigen recognized by monoclonal antibody OC125 produced by immunization of mice with ovarian carcinoma cells. Although CA125 antigen was adsorbed by 130-22 antibody, 125I-labeled 130-22 did not compete with OC125, indicating that although these two antibodies recognized CA125 antigen, they reacted with separate antigenic determinants. The antigen defined by both antibodies was thought to be heat-labile glycoprotein with a molecular weight of over 1,000,000. A series of immunoradiometric assays was developed using combinations of two monoclonal antibodies in a simultaneous forward sandwich mode. Mixed monoclonal antibodies may provide a more sensitive assay for the detection of CA125 than the homologous assay, in which OC125 was used both as a tracer and as a catcher. These results indicate that CA125 is an antigen with two separate epitopes present in both ovarian and lung adenocarcinomas and that combination use of monoclonal antibodies reactive with different antigenic determinants will give certain advantages to the immunoradiometric assay of cancer markers.

Adenocarcinoma↗
PubMed1987

Radioiodinated 2'-iodospiperone: a new radioligand for in vivo dopamine receptor study.

In vivo dopamine receptor binding of the newly synthesized ligand, 125I-2'-iodospiperone (125I-2'-ISP), was studied in mouse brain. The highest accumulation was found in the striatum. Analysis of the striatal homogenate showed the 125I-2'-ISP to be metabolically stable. Furthermore, this striatal binding was saturable and displaced only by dopaminergic drugs. On the other hand, the accumulation in the cortex was as low as that of the cerebellum and uneffected by the administration of serotoninergic drugs and dopaminergic drugs; results assessed by macroautoradiographic studies. Thus, the newly synthesized 125I-2'-ISP presented high affinity for dopamine receptors in vivo and therefore, holds great potential for the in vivo dopamine receptor studies, provided 123I becomes readily available.

Animals↗
PubMed1987

Pontine ataxic hemiparesis studied by a high-resolution magnetic resonance imaging system.

Using a high-resolution magnetic resonance imaging system, we studied 3 patients who had exhibited pontine ataxic hemiparesis. In each patient, the ischemic lesions responsible for the contralateral ataxia were located in the dorsomedial basis pontis. The isointensity bands in the ischemic area on T2-weighted images showed the spared transverse fibers originating from the contralateral pontine nuclei, and this may explain the cause of the unilateral ataxia.

Ataxia↗
PubMed1987

Reactive endosteal bone formation.

The microstructure of reactive endosteal new bone was examined using undecalcified ground sections in five pathologic conditions (bone metastasis from prostate cancer in seven cases, intervertebral osteochondrosis in five, Paget disease in four, chronic suppurative osteomyelitis in two, and fracture healing in one). To determine a basic form of rapid intramembranous bone formation, fetal rat calvaria and primitive bones made in clonal osteogenic cell culture were also observed. In slow bone-forming conditions, lamellar new bone was deposited on pre-existing trabecular surface and caused trabecular thickening on radiographs. In contrast, in rapid bone-forming conditions, woven bone was deposited as spicules extending from trabecular surface so as to form new networks in intertrabecular space. This causes obscurity of trabecular margins radiographically. Reactive endosteal bone formation may be nonspecific and have a significance for assessing the virulence of underlying pathologic conditions like periosteal reactions.

Aged↗
PubMed1987

Interventricular septal motion in acute myocardial infarction with proximal and distal left anterior descending coronary lesions.

To evaluate the ability of echocardiography to detect and localize lesions of the proximal and distal left anterior descending (LAD) coronary arteries, the systolic excursion of the left side of the septum and the ratio of septal to posterior wall excursion (IVS/PW) were measured in 26 patients with acute myocardial infarction (AMI) and nine normal control subjects. The patients with proximal LAD lesions had septal wall excursions of less than 3 mm, whereas in those with distal LAD lesions septal wall excursions were more than 3 mm. All patients with proximal LAD lesions showed an IVS/PW ratio of less than 0.4, but in those with distal LAD lesions the ratio was 0.4 or greater. We conclude that reduced or absent interventricular septal motion in anterior AMI suggests an LAD lesion, and a septal excursion of less than 3 mm suggests involvement of the proximal LAD artery, whereas septal excursion of 3 mm or more indicates involvement of the distal LAD artery.

Adult↗
PubMed1987

Procurement of radioiodinated glucose derivative and its biological character.

Radiolabeled glucose derivatives are attracting great interest in the clinical field. Development of an analogous substrate labeled with a practical radionuclide, 123I, is most desirable, however, no radioiodine labeled glucose derivative has been reported as being chemically and biologically compatible. Thus, in the present study, a glucose derivative substituted at the C-2 position by a p-iodobenzyl group, a 2-O-(p-iodobenzyl)-D-glucose (IBG) was designed and its synthesis was carried out. A very easy and simple synthetic method was developed, and the obtained IBG showed appropriate purity and stability for its radioiodination. [125I]IBG was obtained by radioisotopic exchange reaction with high radiochemical purity and radiochemical yield, requiring no purification. The good in vivo and in vitro stability and the chemical and biological characteristic displayed by the new [125I]IBG stimulated the measurement of the brain uptake index (BUI). In the presence of glucose, brain uptake inhibition was detected, a good indication of a glucose carrier mediator for the transport of [125I]IBG through the blood-brain barrier, a similar feature to that of [14C]glucose or 3-O-[14C]methylglucose. The newly designed ligand IBG holds good promise for the study of regional cerebral glucose utilization, should the 123I become available.

Animals↗
PubMed1987

Endometrial cysts of the ovary: MR imaging.

Magnetic resonance (MR) images of 15 cases of ovarian endometrial cyst were reviewed. With a high-field-strength (1.5-T) MR imager, T1- and T2-weighted images were obtained in axial and sagittal planes, with 5-mm section thickness. MR findings highly suggestive of an endometrial cyst included adhesions to the surrounding organs (e.g., loss of clear margin of the uterine body and tethered appearance of the rectum); a distinct low-intensity zone surrounding a cyst loculus on both T1- and T2-weighted images produced by a thick fibrous capsule; loculus contents with short T1 and long T2 values, attributed to hemorrhagic fluid; and prominent low intensity (shading) within a loculus on T2-weighted images, the mechanism of which is yet to be determined.

Adult↗