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Biomedical subjects

S Inao

Publications and source records attributed to S Inao.

At least 73 records · Page 4Linked to original sources
PubMed1990

Effect of mannitol on intracranial pressure-volume status and cerebral haemodynamics in brain oedema.

Continuous measurement of CBV and CBF by means of laser-Doppler flowmetry was performed to analyze the temporal profile of cerebrovascular response to water accumulation in an infusion model of brain oedema. Using this method, the effect of mannitol on CBV was also examined to determine how mannitol improves the intracranial pressure-volume relationship. The results show that: (1) The presence of an oedema generator elicits a continuous reduction of CBV and a transient reduction of CBF. With cessation of this mechanical force of oedema production, CBV and CBF return to control levels. (2) Mannitol increases CBV and PVI. The improvement of PVI might be due to an increase in CBV as well as ICP reduction.

Animals↗
PubMed1990

The effects of cerebral haemodynamics on the progression of cold-induced oedema.

A cold-injury lesion was made on the brain of 14 of 21 adult mongrel cats. Cerebral blood flow (CBF) and cerebral blood volume (CBV) were observed in both groups during the next 6 to 9 hours using a laser Doppler flow meter. Intracranial pressure (ICP), water contents, and blood pressure were also measured. Hyperemia frequently reached a peak early in the test period in the gray matter and somewhat later in the white matter. In a few cases, hyperemia was observed to occur late in the test period in the gray matter and even later in the white matter. The least frequent pattern was a continuous decrease of CBF and CBV in gray matter over time and of CBF in white matter. Intracranial pressure rose rapidly and correlated well with the early hyperemia. The water content was significantly increased in the white matter. However, the difference in the rate of the increment of the water content was not significant from 7-9 hours after injury. Hyperemia seems to cause the severe impairment of the microcirculation during oedema formation induced by cold injury. A time difference of hyperemia was detected in the gray matter and the white matter.

Animals↗
PubMed1990

An electron microscopic and electron probe study of the microcirculation in cold-induced oedema.

An ultrastructural study of adult mongrel dogs and cats was made to evaluate the changes in the microcirculation during cerebral oedema formation. Two to five cold injuries were made in one hemisphere in dogs and one lesion was made in cats. In several dogs arterial hypertension was induced with a balloon in the aorta. Intracranial pressure (ICP) and water content were measured. The specimens from the oedematous region were studied with transmission electron microscopy (TEM) and electron probe x-ray micro-analysis (EPMA). The TEM data showed swelling of the endothelium and astrocytic foot processes, enlarged perivascular spaces and increased number of endothelial vesicles. The EPMA findings indicated increases in Fe and Ca content in the perivascular spaces. In some cases, the amount of chloride in red cells was increased. The altered distributions of these metals suggested tissue injury and impairment of red cell and vessel wall functions.

Animals↗
PubMed1990

Changes in spinal cord function evaluated by evoked potentials and spinal cord blood flow from a lateral retraction post-cervical laminectomy.

We induced ischemia and stretching by retraction of the spinal cord after laminectomy in 12 anesthetized mongrel adult cats, recorded spinal motor evoked potential (SpMEP) and spinal somatosensory evoked potential (SpSSEP) and determined the spinal cord blood flow (SCBF). The results showed a correlation between progressive deterioration of the function and a decrease in SCBF. Comparing the abnormal findings of both the peak and interpeak latencies in evoked potentials, useful data were more frequently obtained using SpSSEP than SpMEP. Factors involved in their deteriorations seem to be a moderate ischemia by compression, and a stretching by the retraction of the spinal cord. From these results, we conclude that SCBF and SpSSEP are important for monitoring the impulse propagation during retraction of the cervical cord.

Animals↗
PubMed1990

[PVI in analyzing pressure volume relationship--effect of a bolus mannitol administration].

It has been considered that mannitol reduces a raised intracranial pressure effectively by improving pressure volume relationship. The objective of this study is to determine how the pressure volume status is changed by a bolus mannitol administration with using several biomechanical parameters (intracranial pressure, pressure volume index, and intracranial elastance). Our data indicated that mannitol changed the PVI more sensitively than ICP and elastance. "Estimated Intracranial Volume Change (EICVC)" has been newly defined during mannitol infusion on the basis of PVI and ICP change. EICVC for first 30 minutes-period at which the intracranial pressure most vigorously decreased was only about 5 ml in volume. The temporal course of EICVC and ICP were not different, thus, it could account for the change of ICP properly. However, the temporal course of PVI indicating the intracranial venous blood pooling, can not be explained only by EICVC since the PVI has been changed more rapidly than any other parameters. Therefore, we speculated that the ratio of intracranial components could be more largely altered by mannitol than the net of intracranial volume change. The fundamental mechanism of ICP reduction by mannitol is possibly the brain water movement into venous circulation.

Adolescent↗
PubMed1990

In vivo characterization of infusion edema by magnetic resonance imaging.

In vivo measurements of relaxation time profiles were carried out in cats using the infusion model of edema. These profiles were correlated with independent gravimetric measurements of brain water. The results indicated that in vivo determinations of water content by MRI are possible with high spatial resolution.

Animals↗
PubMed1988

Production and clearance of lactate from brain tissue, cerebrospinal fluid, and serum following experimental brain injury.

Lactate dynamics in the brain, cerebrospinal fluid (CSF), and serum were studied in 20 chloralose-anesthetized cats following fluid-percussion trauma. Brain lactate and brain tissue pH were measured by hydrogen-1 and phophorus-31 magnetic resonance spectroscopy. The CSF, arterial, and cerebrovenous serum lactate levels as well as serum glucose concentration were quantified. In the six sham-operated control animals, brain, CSF, cerebrovenous, and arterial lactate levels as well as brain pH remained at normal values. In the five animals in the mild-trauma group (1.6 atm), brain and CSF lactate levels were moderately elevated, although the brain pH and serum lactate content remained at control values. Severe trauma (3.1 atm) in nine cats produced an 82% increase in the brain lactate index and a reduction in brain tissue pH (7.02 +/- 0.02 to 6.95 +/- 0.02; mean +/- standard error of the mean), indicating brain tissue acidosis caused by excessive lactate accumulation. Brain lactate levels reached a peak 1 1/2 hours after severe trauma, then steadily decreased to normal levels by 8 hours posttrauma. Maximum increases of CSF and arterial lactate levels (from 1.4 +/- 0.2 to 4.1 +/- 0.4 and from 1.6 +/- 0.2 to 4.1 to 0.6 mmol/liter, respectively) were observed 15 minutes after trauma, and the values decreased during the next 2 hours. The response was biphasic, with a secondary rise observed in both CSF and serum lactate levels during the remaining 4 hours of the experiment. The difference between the arterial and venous lactate levels (A-Vlact) gradually increased and reached a peak 2 hours postinjury (from -0.05 +/- 0.10 to -0.41 +/- 0.09 mmol/liter). The results of this study show that the production of lactate in brain tissue, CSF, and blood increased in proportion to the severity of the injury. The observation that lactate levels in blood and CSF are maximum immediately following impact while brain lactate and A-Vlact are gradually increasing suggests that the brain-tissue production of lactate fails to account for the rapid appearance of lactate in CSF and blood. It is speculated that the initial elevation of CSF lactate values reflects the systemic response of trauma, and the secondary rise of CSF lactate levels following severe trauma is due to slow seepage of lactate produced by brain tissue into the CSF space. These studies are the first to describe the temporal profile of brain lactate production and eventual clearance by CSF and blood in fluid-percussion injury.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Spin-lattice relaxation times of bound water--its determination and implications for tissue discrimination.

Measurements were made of T1 of bound water (T1b) and bound water fraction (alpha) for gelatin solutions and human tissues (sera, brain tumor, cerebral white matter). Bound water fraction in each sample was measured by means of thermal analysis (differential scanning calorimetry: DSC). T1 values were measured by FONAR QED 80-alpha. T1b values were calculated by an equation derived from the fast-exchange two-state model. In the study of gelatin solutions, the relationship between T1 and water content differed depending on the sort of solutions. This was considered to be due to differences in T1b values. In each biological tissue the values of T1b and alpha had different distributions. These results indicate that values of T1b and alpha for biological tissues may be altered in correspondence to the changes in pathophysiological states in those tissues.

Blood↗
PubMed1987

[Thermal analysis on water components in brain tissue--quantitative determination of free and bound water fractions].

In the living system, tissue water is considered to be composed of both free and bound water. Bound water encompasses the structural water of the cell wall and of various biological substances of high molecular weight, such as proteins and polypeptides. The present study was designed to measure thermoanalytically free and bound water on a quantitative basis in fresh brain of rats using differential scanning calorimetry (DSC). Our intention was to determine the fraction of freezable water in tissue. Freezable water in a tissue represents the fraction of free water. In the present study, freezing was conducted at a constant rate of -10 degrees C/min from room temperature to -75 degrees C by a SSC/560 S (Seiko Electronics). The system allows for calculation of the amount of free water from the differential scanning calorimetry curve employing a coloric constant of 79.4 cal/mg. Aluminium oxide was used as calorimetric reference. The fraction of bound water was calculated by subtraction of the amount of free water from that of total tissue water. Water binding to solid tissue component was estimated from tissue dry weight and the bound water fraction. Mean water content of normal gray matter in adult Wistar rats was 76.9 +/- 1.4% (SD). 88.9% of total tissue water was free whereas 11.1 +/- 2.8% (SD) was bound. Bound water of brain parenchyma amounted to 0.44 +/- 0.12 mg/mg dry weight. As compared to other tissues such as cardiac muscle and liver, brain parenchyma obviously exceeded in free water content. The total water content of serum was 94.4 +/- 1.2%; 90.7 +/- 2.6% was free and 9.3 +/- 2.6% (SD) was bound.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Evaluation of peritumoral edema by proton T1 values with special remarks on time courses following intracranial surgery].

Proton NMR is said to be sensitive to change in tissue water content. Much more attention has been paid to clinical NMR technique for evaluating pathophysiological states including intracranial edema dynamics. This paper describes the follow up data in NMR imaging and spin-lattice relaxation time (T1) measurement in peritumoral brain tissues. Special attention was directed to the time course of focal T1 values before and after surgery. Twenty-one patients with brain tumor, including 6 meningiomas, 7 gliomas and 8 metastatic tumors, were subjected to the present studies in the term from March 1983 to September 1985. Age distribution of this series ranged from 39 to 74 years (average: 58.2). Fonar QED 80-alpha system was applied for NMR examinations of dual modes (static magnetic field: 433 gauss), i.e. image display by steady state free precession (SSFP) and in vivo T1 measurement by field focussing technique. Standard T1 values for healthy brain were 290 +/- 41 ms and 230 +/- 34 ms (mean +/- SD) in cerebral gray and white matter, respectively. Both T1 values in tumors and in peritumoral tissues before craniotomy were obviously prolonged as compared to standard T1 of corresponding site. However, it remained difficult to discriminate statistically these histological differences by preoperative T1 values. Time course of peritumoral T1 was characteristic in accordance with the sorts of brain tumor. T1 values in the brain parenchyma around meningioma were shortened after operation in the earlier stage up to 1 month, showing relatively rapid normalization in T1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1986

Characterization of the phosphoenzyme that is involved in the Ca2+ -Ca2+ exchange catalyzed by the Ca2+ -ATPase of sarcoplasmic reticulum vesicles.

The rate of Ca2+ efflux was determined with 45Ca2+ -loaded sarcoplasmic reticulum vesicles (mainly with the light fraction of vesicles) at pH 6.5 and 0 degrees C. The efflux depended on external Ca2+, Mg2+, ATP and ADP, but it was not activated by AMP. The results indicate that the efflux is derived from Ca2+ -Ca2+ exchange mediated by the phosphoenzyme (EP) of membrane-bound Ca2+ -ATPase. EP was formed with Ca2+ -loaded vesicles (light fraction) under similar conditions without added ADP. The subsequent addition of EGTA and ADP induced triphasic EP dephosphorylation. Three species of EP (EP1, EP2, and EP3) were distinguished on the basis of this dephosphorylation kinetics, EP1, EP2, and EP3, corresponding to the first, second, and third phases of the dephosphorylation. Dephosphorylation of EP1 and EP2 resulted in stoichiometric ATP formation, while dephosphorylation of EP3 led to stoichiometric Pi liberation. The rate of Ca2+ efflux was compatible with that of EP2 dephosphorylation, whereas it was much lower than the rate of EP1 dephosphorylation and much higher than the rate of EP3 dephosphorylation. The intravesicular Ca2+ concentration dependence of the rate of EP2 dephosphorylation agreed with that of the rate of Ca2+ efflux. The results suggest that isomerization between EP1 and EP2 is the rate-limiting process in the Ca2+ -Ca2+ exchange and that EP3 is not involved in this exchange.

Adenosine Diphosphate↗
PubMed1986

[Hemodilutional therapy in raised intracranial pressure; observations in a case of cerebral infarction associated with polycythemia vera].

A 36-year-old man presented with sudden onset of hemorrhagic cerebral infarction in association with polycythemia vera. On admission this patient manifested semicomatous state and left hemiplegia which were gradually progressed. X ray CT demonstrated a severe hemorrhagic infarction in right MCA territory accompanying marked shift of midline structures. Cerebral angiograms represented occlusion of right MCA showing floating emboli in the internal carotid. Hematocrit value was found to be high as 61.2 per cent. Elevated ICP levels were noted by means of epidural pressure monitoring. Deterioration of patient status was considered to be based on impairment of cerebral circulation due to hemostasis by elevated blood viscosity. In addition to administration of mannitol solution, intermittent exsanguinations, 1000 ml in total amount, were performed and hematocrit levels were corrected by hemodilution. Consciousness level was remarkably improved in accordance with reduction of ICP, which well corresponded to values of hematocrit. Level of ICP and tissue perfusion are convinced to be strongly affected by hemorheological factor in the state of raised ICP.

Adult↗
PubMed1986

[Study of local shiftings of the brain stem in increased intracranial pressure by a supratentorial balloon].

The study of the mechanism of pressure transmission is important for the treatment of rapid deterioration of a patient's condition with increased intracranial pressure (ICP) from a space taking lesion in neurosurgical practice. The aim of this experiment is to clarify the mechanism of pressure transmission during supratentorial balloon inflation, by continuously monitoring local shiftings of the brain using strain gauge sensors. Mongrel dogs and macaca fuscatas were fixed in stereotaxic head frames with light anesthesia. Brain shiftings were evaluated by sensors discriminating two dimensional directions, sagittal and coronal planes, at the cerebrum. Brain stem shift was measured as displacement from the midline at the midbrain and ventro-dorsal shifting in the pons. ICP was raised by inflation of a supratentorial balloon located in the frontal lobe in one group or the temporal lobe in other group. As parameters detecting the changes in the functions of the brain stem, systemic blood pressure (SAP), respiration and pupil size were simultaneously monitored. Shifting of the brain stem occurred in four staged in both groups. During a minimum increment of ICP shifts to the antiballoon side were observed at the occipital lobe and the midbrain. The pons showed no shift in stage I. During the further inflation of the balloon stage II, the pons started to shift to the ventral side. In this stage the temporal lobe, in addition to the occipital lobe, shifted to the antiballoon side. There was a tendency for stage II to last longer for the frontal balloon than for the temporal balloon.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

[Time course of NMR images and T1 values associated with hypertensive intracerebral hematoma].

The present study describes time courses in tissue T1 values, as well as in NMR imagings, associated with hypertensive intracerebral hematoma (ICH). Non-operative 21 cases of ICH were examined by FONAR QED 80-alpha NMR system, which possessed dual modes of image display and focal T1 measurement (static magnetic field: 433 gauss). As the first step of examination SSFP images are displayed and then, at the regions of interest, absolute values of T1 are measured by field focusing technique. The extent of ICH was revealed as high density zone in NMR imaging, occasionally represented much wider extent of high density area than the finding on X-ray CT. Prolonged T1 values were obtained from such high density zone. This wide-spread high density area was regarded to reflect the spread of perifocal brain edema. T1 value of the hematoma itself was rather shortened in its initial phase within 2 weeks, thereafter followed by prolongation in the time lapse. This seemed to reflect the alterations in the properties of hematoma such as clot formation in earlier phase and resolution in later phase. On the contrary, T1 in the brain tissue surrounded to hematoma was apparently prolonged in the early phase within 2 weeks, representing the maximal values of 312 msec around 2 to 4 weeks after the onset, and then gradually normalized in the period over 1 month. This alteration in tissue T1 likely represents the processes of edema formation and its regression in perifocal zone. T1 values measured in perifocal region might be available for the evaluation of edema state in association with cerebrovascular accident.

Adult↗
PubMed1984

[A biological rhythm in a patient with normal pressure hydrocephalus--comparative studies in pre- and postoperative patients by a polygraphy].

The authors had studies the correlation between the appearance of the pressure waves and the level of the sleep in pre- and postoperative patients with normal pressure hydrocephalus (NPH). The changes from preoperative findings to postoperative ones were discussed in detail with the relation of the pathophysiological state in these patients. Seventeen patients were evaluated for the suspected diagnosis of the disease of NPH. Thirteen patients of them were treated with ventriculo-peritoneal shunts. Four representative cases among them were evaluated by pre- and postoperative polygraphic studies. A polygraphic overnight study includes a monitoring of an intracranial pressure (ICP), electroencephalography (EEG), electrooculography (EOG), respiratory movement and electromyography (EMG). Each data was recorded for the analysis on data recorder using a computer system. A pressure waves (largely B type) appeared accompanied with an apnea at a resting state (so-called sleep) of each patients. An arousal response in EEG was also observed in the raising period of the pressure waves. At the peak respiration was resumed with transient activities in EMG and continued to the disappearance of the pressure wave. Pressure waves were observed frequently and continually in hours in the resting state of these patients. As a result the level of sleep alternated frequently between an awake stage and a stage 1, including extremely rare appearance of stage 2. In short, the level of sleep was frequently interrupted by the appearance of the pressure waves and apneas. Such pathological states of patient's sleep were involved in the entity of the sleep apnea syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗