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Biomedical subjects

J Ikeda

Publications and source records attributed to J Ikeda.

At least 109 records · Page 6Linked to original sources
PubMed1991

Topographical gradient in expression of R2D5 antigen in superior olivary nuclei and hippocampal dentate gyrus of the cat.

An immunohistochemical analysis of the cat central nervous system revealed that a monoclonal antibody which recognizes a soluble cytosolic protein, R2D5, bound two regions in a prominent spatial gradient. In the medial and lateral superior olivary nuclei of the brainstem, R2D5 immunoreactivity appeared as a gradient across a population of topographically ordered principal neurons. The spatial gradient corresponded to the tonotopic organization in the superior olivary nuclei: i.e., R2D5 immunoreactivity tended to occur more frequently and intensely in low-frequency neurons than in high-frequency neurons. Granule cells in the hippocampal dentate gyrus also had a pronounced spatial gradient in R2D5 immunoreactivity expression, and this gradient corresponded to the septotemporal axis of the hippocampus. Granule cells of the temporal (ventral) portions of the hippocampus were labeled intensely with R2D5 antibody, while those located in progressively more septal (dorsal) portions had gradually less immunoreactivity. These results suggest that in both the superior olivary nuclei and the hippocampal dentate gyrus, neurons differ in intrinsic properties by their position along specific axes. They suggest also that the hippocampus has an intrinsic functional organization related to the spatial gradient along its septotemporal axis.

Animals↗
PubMed1991

Responses of atrium and ventricle to sustained sympathetic nerve stimulation.

To determine whether chronotropic and atrial inotropic responses to sympathetic nerve stimulation are maintained longer than ventricular inotropic response, the present study was performed with control and acute reserpinized dogs. We stimulated the right stellate ganglion of both groups supramaximally for 60 min and compared right atrial responses (chronotropism and inotropism) with left ventricular (LV) dP/dtmax. In the control group, heart rate (HR) immediately increased and was only slightly attenuated with 60 min of stimulation, and right atrial (RA) inotropic response was less attenuated than was LV response (7% in HR, 33% in RA dP/dtmax, 50% in LV dP/dtmax, P less than 0.01, from the peak value of each response). RA and LV norepinephrine (NE) content was decreased by the stimulation but remained higher than the LV control value. In the reserpinized group, NE content in the RA was low before the stimulation and was further decreased by the stimulation. In this group, HR response was attenuated (27% in HR, P less than 0.01) as was LV dP/dtmax, and the difference in contractile responsiveness between atrium and ventricle disappeared (58% in RA dP/dtmax vs. 61% in LV dP/dtmax, NS). The results indicate that the chronotropic response was only slightly attenuated and that the atrial contractile response was attenuated less than the ventricular response, with sustained sympathetic nerve stimulation in the normal heart. This can be ascribed to the much higher NE content in the RA than that in the LV.

Animals↗
PubMed1991

[Distribution of glycoconjugates in gerbil hippocampal neurons--histochemical study with lectins].

Paraffin-embedded sections of gerbil hippocampus were made and stained by use of lectins with different sugar specificities: Concanavalin A (Con A), wheat germ agglutinin (WGA), Ricinus communis agglutinin (RCA), Phaseolus vulgaris agglutinin (PHA-E), peanut agglutinin (PNA), soybean agglutinin (SBA), and Vicia villosa agglutinin (VVA) to investigate the distribution of glycoconjugates in this brain region. Nuclear membranes of all the neurons in the hippocampus were positively stained with Con A and PHA-E, whereas WGA revealed definite staining of cell membranes. Endothelial cells of blood vessels were intensely positive to RCA, suggesting its usefulness as a marker of endothelial cells. With SBA and VVA, a few neurons in Ammon's horn were positively stained, while no positive cells were observed in the dentate gyrus. CA2 and the medial part of the CA1 were also positive bilaterally with SBA and VVA. Some neurons in Ammon's horn and dentate gyrus were selectively stained on the surface of their cell bodies with PNA. The present results show that lectins used distinguish different subpopulations of hippocampal neurons, indicating a new possible classification of hippocampal neurons based on their differences in glycoconjugates.

Animals↗
PubMed1991

[Relationships between the amount of total protein in human milk, the volume of produced milk and food intake].

The concentration of total protein in human milk on the 5th or 6th day after full-term, normal delivery was measured in 145 women, and the amount of protein per 24 hours was calculated by multiplying protein concentration by 24-hour milk production for the same day. Relationships between the concentration and amount of protein, milk volumes and food intake during the latter period of the pregnancy were investigated. Quantification theory III statistical analysis was applied to analyze food intake patterns. While no individual food item was shown to be effective in improving quality and quantity of mother's milk, the results suggest that mothers who consumed meat, fish, food prepared with oil, seaweed, cow's milk and fruits frequently, and rarely used coffee; or mothers who consumed confectioneries and food prepared with oil frequently, rarely used coffee and alcohol beverages and disliked spices produced greater volumes of milk or milk containing a greater amount of protein.

Adult↗
PubMed1990

Role of neuroexcitation in development of blood-brain barrier and oedematous changes following cerebral ischaemia and traumatic brain injury.

Potential involvement of neuroexcitatory mechanisms was studied in: 1) repetitive forebrain ischaemia in gerbils, 2) global cerebral ischaemia in rats and 3) cryogenic injury to the cerebral cortex in rats and gerbils. Uptake of 45Ca was used as a marker of injury, whereas ultrastructural localization of calcium was assessed with an oxalate-pyroantimonate method. The blood-brain barrier was evaluated with immunostaining for serum albumin. Changes in extracellular glutamate were estimated by microdialysis and an enzymatic cycling assay. Changes in water content were assessed by specific gravity measurements. Repetitive ischaemia of 3 x 5 min carotid occlusions produced a cumulative effect with regard to development of oedema and neuronal injury. This was associated with several-fold increments in glutamate release after repeated insults, whereas there was no apparent correlation with energy metabolism disturbances. Other studies revealed in all models a development of secondary foci distant to the primary impact of ischaemia or cold lesions, which were characterized by calcium accumulation in swollen dendrites, chronic neuronal changes and intraneuronal uptake of serum proteins, all of these changes being potentially compatible with involvement of neuroexcitatory mechanisms.

Animals↗
PubMed1990

Altered protein kinase C activity in different subfields of hippocampus following cerebral ischemia.

Protein kinase C (PKC) activity was determined in different (membrane, nuclear and soluble) subcellular fractions prepared separately from the CA1 and CA3 subfields of Mongolian gerbils hippocampus at various time intervals following a single 5-min occlusion of the common carotid arteries. Soluble and nuclear PKC activities of the CA1 sector were found to be elevated at 24 hours following the ischemic injury, while PKC activities did not increase in the CA3 region until the 3rd day after ischemia. The ratio of soluble/membrane-associated PKC activities followed a similar pattern, predominantly because the activation/elevation and then down regulation of the cytosolic enzyme pool changing correspondingly to the ongoing pathological processes. PKC activity returned to the normal level in each subfraction of the CA3 subfield by the 7th day. However, PKC activity remained elevated in the soluble fraction of the CA1 sector even after the delayed death of pyramidal neurons, presumably because of the reactive response of astrocytes. Conceivably, the transient activation and rapid down regulation of PKC in the CA1 sector may contribute to the initiation of postischemic neuronal death in the CA1 subfield.

Animals↗
PubMed1990

Monoclonal antibody R2D5 reveals midsagittal radial glial system in postnatally developing and adult brainstem.

Radial glial cells and their processes play critical roles in organizing the spatial arrangement of the nervous system in the embryonic brain. It has been thought that following completion of their roles in the embryo, most of the radial glial processes disappear before or shortly after birth. Here we use R2D5, a monoclonal antibody to a soluble cytosolic protein, to demonstrate that a specific system of midsagittal radial glial cells persists in postnatal and adult brain. In the brainstem of postnatally developing and adult rabbits and cats, the R2D5-positive processes of radial glial cells were observed to be arranged in a precisely parallel array at the midsagittal seam. These radial glial processes formed a continuous palisade separating the right and left brainstem. In early postnatal animals, R2D5-positive radial processes were found to reach the pial surface and to cover the entire midsagittal seam of the brainstem. These processes embraced dendrites and somata of neurons in almost all of the midsagittal nuclei, including the raphe nuclei, suggesting that the radial glial cells may interact with the midsagittal groups of neurons. In addition, the palisade of R2D5-positive radial processes formed loose openings for crossing axonal bundles at the midline decussations of fiber tracts. In more mature brains, somata of R2D5-positive radial glial cells that had migrated ventrally were observed within the palisades, and in adult cats, most of the R2D5-positive radial processes were found to have retracted from the ventral parts of the midsagittal seam. The spatial arrangement of R2D5-positive processes suggests that they may have persistent functional roles as an interface between ventricular humoral signals and midsagittal groups of neurons in the postnatally developing brainstem and in the adult brainstem. The structure of the midline glial system suggests also that it plays a role in organizing the spatial arrangement of decussating axons during development.

Aging↗
PubMed1990

[A study on immunoglobulin A in human milk. Relationship between the amount of IgA and perinatal factors including food intake].

The concentrations of IgA in human milk on the 5th or 6th day after delivery were measured in 117 women who delivered maturely, and the amount of IgA per 24 hours was calculated by multiplying the IgA concentration by the total milk volume of the same day. The relationship between the amount of IgA and perinatal factors, including food intake during the latter half of the pregnancy, were investigated. Subjects were divided into three groups (little, moderate, much) by the amount of IgA per 24 hrs and quantification theory II statistical analysis was applied to discriminate among the three groups using 13 factors concerning the perinatal period and food intake as explanatory variables. 1. The ratio of correct classification into the three groups was relatively high, suggesting that there is a relation between the amount of IgA in milk and perinatal and food intake factors. 2. Among the perinatal factors, the age, the gestation period and the number of experienced deliveries were effective for the amount of IgA. The obtained results showed that women 20-29 years old who had the first delivery after 38-40 weeks of gestation were liable to have the greatest amount of IgA in milk. 3. The amount of IgA of the women who ate less in the latter period of pregnancy compared with pre-pregnancy, or had a "less frequent intake of protein" was liable to be the greatest, and that of women with a "large volume" or "frequent protein intake" was liable to be greater than that of those with "the same volume" or "moderately frequent protein intake." The amount of IgA of the women with a "frequent intake of salted dried fish" was the greatest. The fact that the amounts of IgA of the women who "ate less" or had a "less frequent intake of protein" were liable to be the greatest was considered to show that toxemia or the tendency to near abortion or preterm delivery greatly affected the amount of IgA.

Adult↗
PubMed1990

Lymphocytic adenohypophysitis accompanying occlusion of bilateral internal carotid arteries--case report.

A 45-year-old female presented with blurred vision, headache, and abnormal thirstiness. She was not pregnant nor postpartum. She had diabetes insipidus and bitemporal hemianopsia. Radiological evidence suggested a mass arising in the sella turcica with extension into the parasellar and suprasellar regions. Carotid angiography showed occlusions of bilateral internal carotid arteries at the cavernous portions. The mass was subtotally removed by the trans-sphenoidal approach and was histologically diagnosed as an adenohypophysitis. Laboratory data showed the patient to be in an active state of autoimmune disorder and hypopituitarism. When a patient presents with pituitary insufficiency and an enhanced intrasellar mass lesion on computed tomographic scan, lymphocytic adenohypophysitis must be included in the differential diagnosis.

Autoimmune Diseases↗
PubMed1990

[Ruptured arteriovenous malformation during pregnancy with special reference to diagnostic X-ray exposure. Case report].

A 32-year-old female (gravida 2, para 2) was admitted at 15 weeks of gestation with a chief complaint of left homonymous hemianopsia accompanied by frontal headache. Computed tomography scan and cerebral angiography were performed with the lead shield and probe for X-ray exposure placed on the patient's body. Angiography revealed an arteriovenous malformation (AVM) located in the posterior part of the right temporal lobe. Total dose of the diagnostic X-ray radiated to the fetus was measured 2.5 mrem at the most. The AVM and the hematoma were totally removed successfully at 19 weeks of gestation. A male infant weighing 3180 g was delivered at full term by cesarean section without congenital anomalies and he has been growing up without mental deficits. These results suggest that diagnostic X-ray examination during pregnancy has little risk and that surgical treatment should be given to the mother immediately after the rupture of an AVM if she is in good condition and the gestational date is past 12 weeks.

Adult↗
PubMed1990

70-kDa heat shock protein and c-fos gene expression after transient ischemia.

Induction of messenger RNA encoding the 70-kDa heat shock or stress protein, hsp70, and the product of the proto-oncogene c-fos was evaluated in gerbil hippocampus by in situ hybridization at various recirculation intervals after 5 minutes of ischemia. Striking increases in c-fos RNA were observed in dentate granule cells within 15 minutes of recirculation and remained evident through 1 hour, returning to undetectable control levels by 3 hours. Modest c-fos hybridization was seen in CA1 and CA3 neurons during the same time course. These results are consistent with the rapid and transient stimulation-induced c-fos expression observed in many experimental systems. Hsp70 expression showed a longer time course, being strongly induced in all major hippocampal neuron populations within 3 hours and persisting for approximately 12 hours in dentate granule cells and through 24 hours in CA3 pyramidal neurons. Notably, the most prolonged expression of hsp70 RNA was observed in vulnerable CA1 neurons that minimally accumulate the immunoreactive protein, with hybridization detected essentially until the death of this cell population at 3-4 days. These studies demonstrate an overlapping distribution of hsp70 and c-fos expression in gerbil hippocampus after ischemia, although there are differences in time course and in the relative induction observed in different neuron populations. The transient increase in c-fos hybridization in dentate granule cells is identical to that seen in various seizure paradigms and provides further support for activation of hippocampal circuitry after ischemia. The prolonged time course of hsp70 messenger RNA expression in vulnerable CA1 neurons may provide a molecular correlate of proposed excitotoxic mechanisms mediating delayed neuronal death.

Animals↗
PubMed1990

Putative neuroexcitation in cerebral ischemia and brain injury.

Involvement of neuroexcitatory mechanisms in cerebral ischemia and brain injury was explored in experimental models of repetitive forebrain ischemia by temporary occlusion of carotid arteries in gerbils and cryogenic injury to the cerebral cortex in rats and gerbils. Our observations in these models revealed a pattern of injury that involved some anatomic structures outside the areas of direct ischemic or traumatic insult. Such foci of injury revealed conspicuously abnormal uptake of 45Ca associated with slight or moderate neuronal alteration, whereas severely injured areas showed no 45Ca uptake. Electron microscopic observations revealed a characteristic presence of calcium in swollen dendrites, closely resembling pictures obtained in neuroexcitatory conditions such as epileptic seizures. Abnormal uptake of 45Ca was associated with apparent blood-brain barrier changes characterized by intracytoplasmic uptake of extravasated albumin into the neurons. Protein synthesis assayed by in vivo [3H]leucine incorporation was reduced in regions showing calcium accumulation. Our observations suggest that neuroexcitation may play an important role in development of secondary and chronic changes after ischemic or traumatic brain insults.

Animals↗
PubMed1990

[Changes in RCBF and edema after transient cerebral ischemia--ischemic threshold of postischemic hypoperfusion].

Brain damage after transient cerebral ischemia may be related to changes in postischemic cerebral blood flow and brain edema. In this study, the relationship between postischemic cerebral blood flow and edema was evaluated in the gerbil. Bilateral carotid occlusion (for 1, 1.5, 5, 15, or 30 min) was carried out in 110 female gerbils (50-70 g) under anesthesia with 2% halothane in 30% O2 and 70% NO2. Cerebral blood flow was measured by a [14C]-iodoantipyrine method modified slightly for use in small animals, and brain edema was evaluated by a specific gravity method. The threshold duration of ischemia which gives rise to subsequent hypoperfusion or edema was also established. In another 52 female gerbils under the same anesthesia, we investigated the effect of ischemia of variable duration on postischemic blood pressure and blood gas. Throughout all experiments, rectal temperature was maintained at 37-38 degrees C with a heating pad. Student's t test was used to calculate statistical significance. Neither blood pressure nor blood gas did vary significantly at any time following recirculation. Each brain region showed the same pattern of blood flow change, one almost independent of duration of occlusion. Namely, after the release of occlusion, transient recovery of blood flow was observed. But the flow then fell to 30-40% of the normal value at 1 h, after which it returned up to normal at 6 h. The severity of postischemic hypoperfusion was also independent of occlusion time. Interestingly, we did not observe postischemic hyperemia in any experimental groups except mild hyperemia in hippocampus after 5 and 15 min ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A computed tomography study on formation, propagation, and resolution of edema fluid in metastatic brain tumors.

Propagation of contrast medium, which extravasated from small metastatic brain tumor, was imaged via CT. By maintaining a constant blood level of the contrast medium by prolonged infusion of 200 ml of 60% meglumine amidtrizoate for 3 hr and thus maintaining a constant passage of contrast labeled edema fluid into the peritumoral extracellular space, the spread of the newly formed edema fluid can be imaged by repeated CTs as a gradually expanding peritumoral circular enhancement into the neighboring white matter. Four patients with small metastatic brain tumor were investigated. CT scans were taken at identical levels 1.5, 3, 6, 9, and 12 hr after start of contrast infusion. After 4 to 7 days of dexamethasone treatment (0.15-0.25 mg/kg/day), the examination was repeated. The area of the expanding circular enhancement was planimetrically measured. From these values, the increase in radius per hour, respectively, in volume per hour were calculated assuming a spherical geometry. These data enabled a determination of the formation rate of edema fluid, of the speed of edema propagation, and of the resolution rate of edema fluid during tissue passage. The formation rate of edema fluid amounted to 0.6 to 3.2 ml/hr depending on tumor diameter and was reduced by about 30% after dexamethasone treatment. Edema fluid traveled 4.8 mm during the first 180 min and 1.9 mm during the consecutive 90 min. The resolution rate of edema fluid during tissue passage amounted to 0.05 ml/hr/cm3 white matter before dexamethasone treatment.

Brain Edema↗