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Biomedical subjects

Y Horikawa

Publications and source records attributed to Y Horikawa.

At least 181 records · Page 10Linked to original sources
PubMed1985

Measurements of in vivo 31P nuclear magnetic resonance spectra in neuroectodermal tumors for the evaluation of the effects of chemotherapy.

The effects of chemotherapy on living tumor tissue in hamsters and rats were investigated by measuring the 31P nuclear magnetic resonance spectra using topical magnetic resonance. Human neuroblastoma, human glioblastoma, and rat glioma tumor cells were inoculated s.c. in the lumbar region of the animals. After the diameter of the tumors increased to 1.5 cm, in vivo 31P nuclear magnetic resonance spectra were measured selectively in the tumors with a TMR-32 spectrometer. Adenosine triphosphate, inorganic phosphate (Pi), phosphodiester, and phosphomonoester peaks were observed. The phosphocreatine peak was hardly detectable, adenosine triphosphate and phosphomonoester peaks were high, and tissue pH, calculated from the chemical shift of Pi, declined. Regardless of the tumor origin or the histological type, the spectral pattern of each neuroectodermal tumor was found to be essentially the same. After i.v. injection of a large dose of a chemotherapeutic agent, adenosine triphosphate peaks decreased and Pi increased gradually, resulting in a dominant Pi peak pattern after 6 to 12 hours. However, during the same period, there were no observable changes in the spectra of normal organs. These findings indicated that the drugs have a selective and direct action on the energy metabolism of tumor cells. With lower drug doses, no remarkable changes were seen in the spectrum. Measurement of in vivo 31P nuclear magnetic resonance spectra is valuable not only to investigate the energy metabolism in tumor tissue but also to evaluate the effects of chemotherapy.

Adenosine Triphosphate↗
PubMed1984

In vivo measurement of energy metabolism and the concomitant monitoring of electroencephalogram in experimental cerebral ischemia.

The energy metabolites in rat brain in vivo were measured by using topical magnetic resonance (TMR) during the whole course of ischemia, in combination with the concomitant monitoring of electroencephalogram (EEG). Immediate loss of high energy phosphorus compounds, phosphocreatine (PCr) and ATP, resulted in the flattening of EEG after the induction of ischemia. PCr and ATP returned to almost normal level 30 min after recirculation of the ischemic brain, but EEG showed no recovery and the abnormality lasted for 12 h. The measurement of in vivo 31P-NMR is essential for the decision of the convalescence of cellular function in the brain.

Adenosine Diphosphate↗
PubMed1984

Measurements of in vivo energy metabolism in experimental cerebral ischaemia using 31P-NMR for the evaluation of protective effects of perfluorochemicals and glycerol.

Effects of perfluorochemical (PFC) and glycerol on energy metabolism in cerebral ischaemia were examined by the sequential measurements of in vivo 31P-NMR spectrum using topical magnetic resonance (TMR). Experimental cerebral ischaemia was induced in forty-five Wistar rats by a four-vessel occlusion method. The 31P-NMR spectrum and the EEG were monitored during preischaemic and ischaemic periods and after circulation was restored for various periods up to 240 min. There were several peaks in the 31P-NMR spectrum of the preischaemic rat brain; beta-ATP, alpha-ATP, gamma-ATP, phosphocreatine (PCr), phosphodiesters, inorganic phosphate (Pi) and sugar phosphate. As soon as the ischaemia was induced, PCr and ATP decreased and Pi increased. The chemical shift of the increased Pi peak decreased, showing acidosis of the brain tissue. After circulation was restored following the 30 min ischaemia, recovery of the 31P-NMR spectrum occurred within 30 min in all sixteen untreated rats. Recovery of the 31P-NMR spectrum was induced by recirculation only in half of the six rats in the untreated 60 min ischaemia group. None of the six rats in the untreated group showed recovery of the spectrum after 120 min ischaemia. When 20% Fluosol-DA was administered at a dose of 20 ml/kg before the induction of ischaemia, all eight rats showed recovery of the spectrum after 120 min ischaemia. Moreover, four of six rats treated with both PFC and glycerol showed temporary recovery even after 240 min ischaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗
PubMed1982

Methylcellulose media for plaque assay of murine leukemia virus.

When ecotropic murine leukemia virus was assayed by a methylcellulose-XC cell procedure, plaque titers showed less test-to-test variation, more uniform dose-response curves, and larger plaque sizes, as compared with results of the conventional liquid overlay-XC cell test system. This assay therefore seems to be reliable and useful for the titration of ecotropic murine leukemia virus.

Animals↗
PubMed1982

Proton nuclear magnetic resonance studies on brain edema.

The water in normal and edematous brain tissues of rats was studied by the pulse nuclear magnetic resonance (NMR) technique, measuring the longitudinal relaxation time (T1) and the transverse relaxation time (T2). In the normal brain, T1 and T2 were single components, both shorter than in pure water. Prolongation and separation of T2 into two components, one fast and one slow, were the characteristic findings in brain edema induced by both cold injury and triethyl tin (TET), although some differences between the two types of edema existed in the content of the lesion and in the degree of changes in T1 and T2 values. Quantitative analysis of T1 and T2 values in their time course relating to water content demonstrated that prolongation of T1 referred to the volume of increased water in tissues examined, and that two phases of T2 reflected the distribution and the content of the edema fluid. From the analysis of the slow component of T2 versus water content during edema formation, it was demonstrated that the increase in edema fluid was steady, and its content was constant during formation of TET-induced edema. On the contrary, during the formation of cold-injury edema, water-rich edema fluid increased during the initial few hours, and protein-rich edema fluid increased thereafter. It was concluded that proton NMR relaxation time measurements may provide new understanding in the field of brain edema research.

Animals↗
PubMed1982

[Nuclear magnetic resonance studies of effects of glycerol on brain edema].

Effects of glycerol on the state of water in edematous brain tissues were studied by the pulse FT NMR technique. Brain edemas were induced experimentally by cold injury and triethyl tin (TET) intoxication in Wistar rats. Ten percent w/v glycerol (1 g/kg body weight) were injected intravenously at 30 minutes before decapitation for the NMR measurements. Transverse relaxation times (T2) in the cerebral gray and white matter were measured by Meiboom-Gill pulse sequence at the resonant frequency of 100 MHz. Water content was calculated from the difference between wet and dry weight after heating in an oven at 95-100 degrees C for 72 hours after the NMR measurements. In the normal brain T2 value was 76.4 msec and 75.4 msec in the gray and white matter respectively. In the edematous brain, T2 separated into two components, one slow and one fast, corresponding with the increase of water content. Values of the slow component (slow T2) were characteristic of both types of brain edema. In the cold injury edema, slow T2 values became 105 msec in the gray matter and 96 msec in the white matter, while in the TET induced edema, it became 450 msec in the white matter. After glycerol infusion, slow T2 became faster in these regions in both types of brain edema, showing 92.1 msec in the gray matter and 88.1 msec in the white matter of the cold injury edema, and 388 msec in the white matter of TET induced edema. The degree of the changes of slow T2 values per unit change of water content was greater in the cold injury edema than in the TET induced edema. Serum osmolality elevated 23.8 mOsmol greater than the control value after glycerol infusion in this experiment. It is concluded from these findings that glycerol retracts free mobile water molecules from the edema fluid by osmotic pressure gradient.

Animals↗
PubMed1981

[Nuclear magnetic resonance studies on brain edema--time course of 1H-NMR relaxation times (author's transl)].

1. The state of water in normal and edematous brain tissue was studied by measurement of proton longitudinal (T1) and transverse (T2) relaxation times using pulsed nuclear magnetic resonance (NMR) technique. 2. In control rats, T1 and T2 of water showed one component, which was more fast in white matter. Those values displayed 1.07-1.18 sec. of T1 and 75-76 msec. of T2. 3. When rat brain was injured by cold, T1 was observed to become more longer (1.18-1.27 sec.), and T2 was observed to be separated into two components, the faster T2 (45-50 msec.) and slower T2 (100-105 msec.), in body gray and white matter of the injured side. 4. In triethyltin (TET) induced brain edema, elongation of T1 (1.2 sec.) and remarkable separation of T2, faster T2 (75 msec.) and slower T2 (400-450 msec.), were observed in white matter. 5. In both cold and TET induced edema, slower T2 fraction is suggested to be the extracellular space and faster T2 fraction, intracellular. 6. T2 changes precede the water content changes in cold injury, and parallel in TET induced edema. Those changes of relaxation times are reversible. 7. T2 changes of water is more sensitive than the T1 for the detection of production and disappearance of brain edema. 8. These results disclose the dynamic movements of water during the course of brain edema and offered significant information of the clinical application of NMR-CT.

Animals↗
PubMed1980

A congenital arteriovenous aneurysm in the neck.

One male case of a congenital arteriovenous aneurysm in the neck was described. It was fed by a distal branch of the external carotid artery and drained into the external jugular vein. A swelling of the neck and a bruit of the ear disappeared following resection of this malformation. Nine published cases are summarized and briefly discussed.

Adolescent↗
PubMed1980

[Bifrontal cystic tumor--a form of suprasellar germinoma (author's transl)].

Twenty year old boy was admitted because of a recent history of generalized seizures and papilledema. Neurological examination was essentially negative except papilledema in the both optic fundi. A history of polydipsia or polyuria was not obtained. CT scan showed bifrontal cystic lesions and cyst walls were partly enhanced. Midline frontal nodules around the foramen of Monro were also revealed by enhancement. Operation was performed and biopsy specimen showed typical histology of germinoma with a small focus of squamous epithels. Postoperatively, the patient's urinary output increased temporalily up to 5,000 ml per day under steroid administration. Shortly after irradiation, cysts decreased in size and all enhanced lesions disappeared completely. The patient is fully working without disturbance one and half year after the onset. Close relationship of germinoma and teratoma was briefly reviewed in literature.

Adult↗