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Biomedical subjects

Y Horikawa

Publications and source records attributed to Y Horikawa.

At least 163 records · Page 9Linked to original sources
PubMed1986

Value of high-resolution computed tomography in diagnosis of petrous bone fracture.

High-resolution computed tomography (CT) was performed on 31 patients clinically suspected of having petrous bone fracture. The location of the fracture was demonstrated accurately in 28 patients (90.3%), whereas it could be diagnosed by plain skull film in only 17 patients (54.8%). The anatomic location of fractures demonstrated by high-resolution CT clearly corresponded to the clinical symptoms and signs. We have classified petrous bone fracture into five types according to the anatomic levels demonstrated on CT images. The findings indicate that high-resolution CT is extremely useful for diagnosing petrous bone fracture.

Humans↗
PubMed1986

Significance of proton relaxation time measurement in brain edema, cerebral infarction and brain tumors.

We examined the proton relaxation times in vitro in various neurological diseases using experimental and clinical materials, and consequently obtained significant results for making a fundamental analysis of magnetic resonance imaging (MRI) as followings. 1) In the brain edema and cerebral infarction, T1 prolonged and T2 separated into two components, one fast and one slow. Prolongation of T1 referred to the volume of increased water in tissue. The slow component of T2 reflects both the volume and the content of increased edema fluid in tissue. 2) In the edematous brain tissue with the damaged Blood-Brain-Barrier (BBB), the slow component of T2 became shorter after the injection of Mn-EDTA. Paramagnetic ion could be used as an indicator to demonstrate the destruction of BBB in the brain. 3) After the i.v. injection of glycerol, the slow component of T2 became shorter in the edematous brain with the concomitant decrease of water content. The effects of therapeutic drug could be evaluated by the measurement of proton relaxation times. 4) Almost all tumor tissue showed a longer T1 and T2 values than the normal rat brain, and many of them showed two components in T2. It was difficult to determine the histology of tumor tissue by the relaxation time alone because of an overlap of T1 and T2 values occurred among various types of brain tumors. 5) In vivo T1 values of various brain tumor were calculated from the data of MRIs by zero-crossing method, and they were compared with the in vitro T1 values which were measured immediately after the surgical operation. Though the absolute value did not coincide with each other due to differences in magnetic field strength, the tendency of the changes was the same among all kinds of tumors. It is concluded that the fundamental analysis of proton relaxation times is essentially important not only for the study of pathophysiology in many diseases but also for the interpretation of clinical MRI.

Animals↗
PubMed1986

Dissociated taste disorder.

Dissociated taste disorder is a special symptom occurring when only one or two taste qualities of the four primary taste are disturbed. Eleven % of all cases of taste disorders complain of this symptom. The subjects of this investigation were 46 patients due to be examined. We used our filter-paper disc method invented for clinical qualitative and quantitative gustometry by taste examination. True dissociated taste disorder was confirmed in 12 patients only with respect to sweetness. No dissociated taste disorder was found for the other types of taste. Sweetness differs from the other three primary tastes in that it is brought about by a protein acting as a receptor. In patients suffering from true dissociated taste disorders, the predominant cause of the condition is zinc deficiency. When zinc is not available in adequate quantities, the synthesis of the protein at the sweet-sensitive receptor site can no longer be achieved smoothly, and this may lead to the development of the complaint.

Aged↗
PubMed1986

Radiofrequency hyperthermia with successive monitoring of its effects on tumors using NMR spectroscopy.

Radiofrequency (rf) hyperthermia was generated on rat glioma inoculated s.c. in CD Fisher rats by applying the rf pulse using the surface coil in the NMR spectrometer, and the effect was monitored successively in the same spectrometer by measuring 31P NMR spectra and 1H NMR images. In the 31P NMR spectrum at the preirradiation stage, nucleoside triphosphate peaks and a phosphomonoester peak were high and a Pi peak was low. After a rf pulse at a power of 5 W was applied continuously for 60 min, the nucleoside triphosphate peaks decreased and the Pi peak increased immediately, resulting finally in a dominant Pi peak pattern within 30 min in all 10 cases examined. These spectral changes occurred much earlier than the histological changes and lasted for at least 7 days. By the 1H NMR imaging, the necrotic region was detected as a high-intensity lesion in spin echo and inversion recovery images 2 days after the irradiation. There were no changes either in the spectrum or in 1H NMR images in any of 8 cases after irradiation with a rf pulse of less than 3 W. Thus, we could generate rf hyperthermia with the NMR spectrometer and the effects were monitored sensitively with the same spectrometer. It can be concluded that the NMR device can be used not only for diagnosis but also as a therapeutic tool.

Animals↗
PubMed1986

Effects of Lactobacillus casei on Pseudomonas aeruginosa infection in normal and dexamethasone-treated mice.

A single intraperitoneal injection of Lactobacillus casei YIT 0003 into normal or dexamethasone-treated mice led to nonspecific resistance against intraperitoneal challenge with lethal doses of Pseudomonas aeruginosa PAO 3047. The enhanced resistance was retained for 14 days (P less than 0.05) after injection with living L. casei. In contrast, the statistically significant duration of the enhanced resistance in mice treated intraperitoneally with living L. acidophilus YIT 0075 was only 5 days. The in vivo killing activity of peritoneal exudate cells (PECs) against P. aeruginosa 5 and 7 days after intraperitoneal injection of living L. casei was significantly higher than in the case of PECs elicited by L. acidophilus. In the case of intravenous injection of heat-killed L. casei before intraperitoneal challenge with P. aeruginosa, there were no survivors in the late period after administration of L. casei. A high correlation existed between the patterns of in vivo killing of P. aeruginosa by PECs and survival rate of mice injected intravenously with heat-killed L. casei. The reduced in vivo killing activity of PECs from dexamethasone-treated mice against P. aeruginosa infection was also augmented by the intraperitoneal injection of heat-killed L. casei. These results indicate that L. casei possesses a resistance-enhancing capacity against P. aeruginosa infection in vivo. Differences in the duration of the enhanced resistance caused by L. casei and by L. acidophilus may be due to differences in chemical composition and/or physicochemical properties of the cell walls of the two kinds of bacteria.

Animals↗
PubMed1986

Evaluation of the effects of photoradiation therapy on brain tumors with in vivo P-31 MR spectroscopy.

In vivo phosphorus-31 magnetic resonance (MR) spectra were obtained by a surface coil method from rat glioma tissue inoculated subcutaneously in CD Fisher rats, and the effects of photoradiation therapy on tumors were evaluated by sequentially observing spectral changes. In the control group, the nucleoside triphosphate (NTP) and phosphomonoester peaks were large, the phosphocreatine peak was small, and the inorganic phosphate (Pi) peak was intermediate. In all eight cases in the group in which a dose of 10 mg/kg of hematoporphyrin derivatives (HpD) was given before photoirradiation, NTP peaks decreased, and the Pi peak increased remarkably within 1 hour after the 60-minute white-light irradiation. Spectral changes were observed before histologic changes were apparent. Histologic examinations 3 days after irradiation showed extensive necrosis in the tumor tissue. With preinjection of 5 mg/kg HpD, three of the eight cases showed spectrum changes after the irradiation. No spectrum changes were observed in the group with preinjection of 2.5 mg/kg. In vivo P-31 MR spectra measurements are useful not only to investigate the energy metabolism of tumor tissue in vivo but also to evaluate the effects of photoradiation therapy on tumors.

Animals↗
PubMed1986

One-shot dual-energy subtraction imaging.

Dual-energy subtraction imaging by a single x-ray exposure (one shot) can easily be performed by using computed radiography with scanning laser-stimulated luminescence. In a phantom study, a thin copper filter placed between two imaging plates produced a dual-energy subtracted image from a single x-ray exposure. One-shot dual-energy subtraction imaging was also useful in the diagnosis of thoracic lesions.

Female↗
PubMed1985

Effects of neonatal treatment with monosodium glutamate on circadian locomotor rhythm in the rat.

In order to study the effects of treatment with monosodium glutamate (MSG) during the neonatal period on the intrinsic circadian timekeeping system in rats, the locomotor activity of blinded MSG-treated and control (saline-treated) rats was analyzed with power spectral analysis and cross-correlation. In contrast to a robust free-running circadian rhythm in the control rats, a significant shortening of the circadian period and rapid decomposition into ultradian components were noted in the MSG-treated rats. Computer-assisted stereometry of the hypothalamic nuclei revealed that, in addition to the well-known severe damage in the arcuate nuclei (ARC), the volumes of the suprachiasmatic nuclei (SCN) and ventromedial hypothalamic nuclei (VMH) were also reduced significantly in the MSG-treated rats. Although no gross histological damage was apparent in either the SCN and VMH, neonatal MSG treatment appears to impair the function of SCN to integrate many minor oscillations in the brain into a single, definite and precise circadian period.

Animals↗
PubMed1985

Observations of energy metabolism in neuroectodermal tumors using in vivo 31P-NMR.

The energy metabolism of living tumors in rats and hamsters were investigated by obtaining in vivo 31P-NMR spectra, and the effects of chemotherapy on tumors were evaluated by observing the changes of these spectra. Tumor cells of rat glioma, human glioblastoma and human neuroblastoma were inoculated subcutaneously in the lumbar region of the animals. After the tumor grew to over 1.5 cm in diameter, in vivo 31P-NMR spectrum data was obtained selectively from the tumor with a TMR-32 spectrometer (Oxford Research Systems, U.K.). Several peaks (ATP, inorganic phosphate (Pi), phosphodiesters and phosphomonoesters (PME) were observed in the tumors. The heights of these peaks varied widely corresponding to the tumor growth. However, the spectrum pattern of each tumor in an active stage was found to be essentially the same regardless of histological type or tumor origin. The phosphocreatine (PCr) peak was small, ATP and PME peaks were large and tissue pH calculated from the chemical shift of Pi was low in each tumor group. After intravenous injection of a large dose of a chemotherapeutic agent, ATP peaks decreased and the Pi peak increased gradually, resulting in a dominant Pi peak pattern after several hours in all groups. With lower drug doses, spectrum changes were temporarily seen in the tumors. These findings indicated that drugs with a high dose have a selective and a direct action on the energy metabolism of tumor tissues. In vivo 31P-NMR spectra measurement is very valuable not only to investigate the energy metabolism in tumor tissue but also to evaluate the effects of chemotherapy on the tumor.

Animals↗
PubMed1985

In vivo studies of energy metabolism in experimental cerebral ischemia using topical magnetic resonance. Changes in 31P-nuclear magnetic resonance spectra compared with electroencephalograms and regional cerebral blood flow.

The energy state of the brain during and after transient cerebral ischemia was examined in rats by in vivo measurement of 31P-nuclear magnetic resonance (NMR) spectra using a topical magnetic resonance spectrometer. EEGs and regional CBF (rCBF) were monitored on the same ischemic models. Immediately after the induction of ischemia, the height of the ATP and phosphocreatine peaks in the spectrum began to decrease with a concurrent increase of the inorganic phosphate (Pi) peak. The calculated pH from the chemical shift of Pi decreased during ischemia. The EEG pattern became flat immediately after ischemic induction. The rCBF decreased below the sensitivity level of the measuring instrument. With 30-min ischemia, the 31P-NMR spectrum returned to a normal pattern rapidly after recirculation. However, recovery of the EEG was delayed. The rCBF after recirculation showed postischemic hyperemia followed by hypoperfusion. In cases of 120-min ischemia, none of the spectra showed recovery. Thus, we could investigate the dynamic process of pathophysiological changes occurring in the ischemic brain in vivo.

Animals↗
PubMed1985

Acute brain edema in fatal head injury: analysis by dynamic CT scanning.

Dynamic computerized tomography (CT) was performed on 42 patients with acute head injury to evaluate the hemodynamics and to elucidate the nature of fatal diffuse brain bulk enlargement. Patients were divided into two groups according to the outcome: Group A included 17 nonfatally injured patients, eight with acute epidural hematomas and nine with acute subdural hematomas; Group B included 25 fatally injured patients, 16 with acute subdural hematomas and nine with bilateral brain bulk enlargement. Remarkable brain bulk enlargement could be seen in all fatally injured patients with acute subdural hematoma. In 29 (69%) of 42 patients, dynamic CT was performed within 2 hours after the impact. In the nonfatally injured patients with brain bulk enlargement, dynamic CT scans suggested a hyperemic state. On the other hand, in 17 (68%) of the 25 fatally injured patients, dynamic CT scans revealed a severely ischemic state. In the fatally injured patients with acute subdural hematoma, CT Hounsfield numbers in the enlarged hemisphere (hematoma side) were significantly lower than those of the opposite side (p less than 0.001). Severe diffuse brain damage confirmed by follow-up CT scans and uncontrollable high intracranial pressure were noted in the fatally injured patients. Brain bulk enlargement following head injury originates from acute brain edema and an increase of cerebral blood volume. In cases of fatal head injury, acute brain edema is the more common cause of brain bulk enlargement and occurs more rapidly than is usually thought.

Acute Disease↗
PubMed1985

[Changes in serum pancreatic enzymes and pancreatic secretory trypsin inhibitor in patients with severe acute pancreatitis].

Serum pancreatic enzymes (amylase, trypsin, pancreatic elastase 1, pancreatic phospholipase A2) and serum pancreatic secretory trypsin inhibitor (PSTI) were measured in 22 patients with moderate or severe acute pancreatitis. Serum levels of all pancreatic enzymes were elevated at the initial determination, but they fell rapidly to normal in both moderate and severe pancreatitis. In contrast, PSTI in severe pancreatitis increased after admission and reached the maximum on the second to the forth day after onset. There was a significant positive correlation between the level of PSTI and that of acute phase reactant (fibrinogen, alpha 1-antitrypsin), and serum PSTI in severe acute pancreatitis changed as if it was one of acute phase reactants. There was also a significant negative correlation between the level of serum PSTI and that of alpha 2-macroglobulin.

Acute Disease↗