Search PubMed⌕ Search

Biomedical subjects

F Ikuta

Publications and source records attributed to F Ikuta.

At least 55 records · Page 3Linked to original sources
PubMed1993

The intermediolateral nucleus in sporadic amyotrophic lateral sclerosis.

Histological and morphometrical observations of the intermediolateral nucleus (IML) at the levels of the upper and lower thoracic segments (T2 and T9) were carried out in 18 patients with sporadic amyotrophic lateral sclerosis (ALS) and 15 age-matched control subjects. Of the 18 ALS patients 6 had been on a respirator before death. No Bunina bodies were found in the IML neurons in either the ALS patients or the control subjects. Only a small number of spheroids were encountered rarely in the IML in both the patients and controls. The number of neurons in the IML in the non-respirator-supported ALS patients were reduced at T2, but well preserved at T9 compared with the control subjects. In the respirator-supported ALS patients, there was a marked reduction of IML neurons at both T2 and T9. Considering the absence of direct synaptic contacts with anterior horn cells, these neurons, without the formation of Bunina bodies, appeared to be involved primarily in the disease process in sporadic ALS.

Adult↗
PubMed1993

Activation of human lysosomal sialidase.

An acid sialidase [EC 3.2.1.18], partially purified from human placenta by Con A-Sepharose adsorption and p-aminophenyl thio-beta-D-galactoside-CH-Sepharose (PATG-Sepharose) affinity chromatographies, was activated by incubation at 37 degrees C. This activation showed both time and temperature dependencies, with the most effective activation observed at 37 degrees C in the pH range between 4.3 and 5.2. The influence of various protease inhibitors on its activation was investigated. Among the protease inhibitors tested, amastatin, an inhibitor of aminopeptidase A, significantly inhibited activation. The partially purified enzyme preparation contained aminopeptidase activity, which was inhibited by amastatin. Zinc ions inhibited either the activation of sialidase or the aminopeptidase activity in the enzyme preparation. These results suggest the possibility of participation of aminopeptidase function in the activation process of sialidase.

Aminopeptidases↗
PubMed1993

Uniform tissue distribution of tRNA(Lys) mutation in mitochondrial DNA in MERRF patients.

We documented the presence of a point mutation in the tRNA(Lys) gene of mitochondrial DNA (mtDNA) in various postmortem tissues from two patients with myoclonus epilepsy associated with ragged-red fibers (MERRF). The percentages of the mutant mtDNA were similar (93 to 99%) in both clinically affected and unaffected tissues, suggesting that preferential clinical involvement of certain tissues in MERRF is based not only on the variation of distribution of the mutant mtDNA, but also on other factors such as differences in the threshold in various CNS regions and organs.

Adult↗
PubMed1993

[Incidental occurrence of Lewy bodies in the brains of elderly patients--the relevance to aging and Parkinson's disease].

The Lewy body (LB) is a cytoplasmic neuronal inclusion that is constantly found in the substantia nigra and locus ceruleus, and other specific brain regions in Parkinson's disease (PD). In the present study, the significance of non-parkinsonian cases in which the LBs were an incidental finding was investigated. In 1,452 autopsy series (age range, 1-89 years), 27 incidental cases of LBs and 21 patients with PD were found. The age-specific prevalence of incidental LBs steadily increased from 0.7% to 6.5% between the sixth and ninth decades. The distribution of LBs in incidental cases was similar to that in PD. The number of neurons in the substantia nigra and locus ceruleus was determined in 8 incidental cases (age range, 60-81 years), 9 patients with PD (range, 56-81 years) and 9 control subjects (range, 60-81 years). In incidental cases, the average numbers of pigmented neurons in the substantia nigra and locus ceruleus was 83% and 77% of those in control subjects, respectively. In PD, the average numbers of pigmented neurons in the substantia nigra and locus ceruleus was 28% and 19% those of controls, respectively. However, the number of nonpigmented neurons in the substantia nigra was not reduced in incidental cases and PD. From the above findings, it is suggested that there exists a close relationship between the occurrence of LBs and aging. However, in the brains of elderly patients, incidental LBs were considered to be pathological findings rather than simple aging phenomenon. Therefore, it has been suggested that incidental cases may represent early and presymptomatic cases of PD.

Adolescent↗
PubMed1993

[Neuropathology required from "brain death"].

We have pathoanatomically investigated Japanese 84 autopsied patients who had been clinically judged to be in a state of "brain death". 1) The finding observed in all the cases was that the brains revealed a severe state of increased intracranial pressure (IICP) with secondary hemorrhages involving the brain stem tegmentum. 2) Autolysis was observed in all the brains, especially in their brain stems, and the degree was always severer than in the visceral organs (VOs). 3) We considered that in all the cases cessation of cerebral blood flow occurred at least in the brain stem tegmentum by the time of the judgements. 4) We pointed out that like the VOs, the spinal cord under a certain level of the cervical segments continued to live until the cardiac stop. 5) We also considered that in nearly half the cases the neurons of the hypothalamus, especially of its supraoptic nucleus, tended to live long, for 3 to 4 days, even after the judgements.

Autolysis↗
PubMed1993

[The aging of central nervous system in methylmercury intoxication in Niigata, Japan--quantitative investigation of neurofibrillary tangles and senile plaques].

In order to elucidate the progression of aging process in the brains of methylmercury intoxication in humans, neurofibrillary tangles (NFT) and senile plaques (SP) were examined quantitatively in the temporal lobe and calcarine cortex of 16 patients with methylmercury intoxication and 12 control subjects by using tau and beta-peptide immunostained preparations. The numbers of NFT and SP in the patients of methylmercury intoxication were almost equal to those in control subjects, and statistically there is no significant difference. The findings indicate that the methylmercury intoxication in humans does not induce or exacerbate the NFT or SP forming disease process at least in these regions in the brain.

Aged↗
PubMed1992

Immunocytochemical localization of synaptic vesicle-specific protein in Lewy body-containing neurons in Parkinson's disease.

We carried out an immunocytochemical examination of the brainstem and sympathetic ganglia of 5 autopsied patients with Parkinson's disease, using monoclonal antibodies against microtubule-associated protein 2 (MAP2) and synaptic vesicle-specific 38 kDa protein (SVP38). Lewy bodies (LBs) in the nerve cell somata were often immunoreactive for MAP2. Immunoreactivity of SVP38 in the somata of nerve cells was rarely demonstrated in the peripheral portion of the LBs. On the other hand, SVP38-immunoreactive (IR) LB-containing nerve cell processes were frequently found in the brainstem and sympathetic ganglia, considerably outnumbering MAP2-IR LB-containing nerve cell processes. These findings suggested that SVP38 is stored in LB-containing nerve cell processes and indicate that the majority of these processes are axons.

Aged↗
PubMed1992

Ultrastructural localization of inositol 1,4,5-trisphosphate 3-kinase in rat cerebellar cortex.

Subcellular localization of inositol 1,4,5-trisphosphate 3-kinase in the rat cerebellar cortex was studied immunohistochemically using a monoclonal antibody. Electron microscopy revealed intense immunoreactivity in the dendritic spines of Purkinje cells forming synapses with the parallel fibers, climbing fibers and recurrent collaterals of Purkinje cell axons. The labelling was associated with the hypolemmal cisternae, surrounding matrix and plasmalemma including the postsynaptic densities. Weaker immunoreactivity was present in the dendritic spines of basket cells and in certain segments of Purkinje cell recurrent collaterals. The postsynaptic regions of the dendritic trunks of Purkinje and basket cells were negative. These results indicate that inositol 1,4,5-trisphosphate 3-kinase is distributed amongst the spines of various synaptic relations with different electrophysiological properties, and that axon terminals of certain cell types are another functional site for the enzyme.

Animals↗
PubMed1992

Remote astrocytic response of prefrontal cortex is caused by the lesions in the nucleus basalis of Meynert, but not in the ventral tegmental area.

The nucleus basalis of Meynert (nbM) was lesioned by injection of ibotenic acid, in 200 g male Wistar rats. The rats were killed 1, 3, 7 or 21 days after surgery, the brains were removed and the prefrontal cortices were subjected to immunohistochemical and Western blot analysis for the expression of glial fibrillary acidic protein (GFAP). In some rats, vehicle was injected into the nbM and in others 6-hydroxydopamine (6-OHDA) was injected into the ventral tegmental area (VTA). Quantitative Western blot analysis revealed significantly greater immunoreactivity for GFAP in the prefrontal cortex of nbM-lesioned rats. Immunohistochemical examination revealed fibrous and hypertrophic GFAP-positive astrocytes even one day after surgery, and this reaction was stronger at 3 days after surgery. After this peak, GFAP-immunoreactivity of the astrocytes decreased from 7 days to 21 days. In contrast, GFAP-positive astrocytes were not observed in the brains of vehicle-injected or VTA-lesioned rats, even 21 days after surgery. The present results indicate that cortical astrocytes respond to cholinergic deafferentation. In addition, our findings provide new insights into the abnormalities of cortical glial cells after cholinergic deafferentation in Alzheimer's disease.

Acetylcholine↗
PubMed1992

Does methylmercury intoxication induce arteriosclerosis in humans? A pathological investigation of 22 autopsy cases in Niigata, Japan.

In order to clarify whether or not arterio- and/or arteriolosclerosis is induced or exacerbated in patients with methylmercury (Me-Hg) intoxication, the pathological features of arteries and arterioles in specific areas in 22 patients and 36 control subjects were examined qualitatively and quantitatively. Vessels investigated were: (1) small arteries and arterioles in the subarachnoid space and cortex of the postcentral gyrus, transverse temporal gyrus, first visual area and cerebellar vermis, as well as the myocardium and renal cortex; (2) the lateral striate artery; (3) the internal carotid, anterior, middle and posterior cerebral, basilar and vertebral arteries, as well as the coronary and renal arteries; and (4) the aorta. The arteriosclerotic changes observed in the patients with Me-Hg intoxication were indistinguishable both qualitatively and quantitatively from those of controls. The results indicate that Me-Hg intoxication does not induce or exacerbate sclerotic changes in arteries and arterioles. Thus, the peculiar neurological symptoms and neuropathological features of Me-Hg intoxication are thought to be induced not by ischemia but by selective primary degeneration of the neurons in specific regions.

Adult↗
PubMed1992

Clarke's column in sporadic amyotrophic lateral sclerosis.

Histological, ultrastructural and morphometrical observations on Clarke's column were carried out in 18 patients with sporadic amyotrophic lateral sclerosis (ALS) and 15 age-matched control subjects. Of the 18 ALS patients 6 had been on a respirator before death. Bunina bodies were found in the neuronal cytoplasm in 7 of the 12 non-respirator-supported ALS patients and in 3 of the 6 respirator-supported patients. The number of spheroids was significantly higher in the non-respirator-supported patients (P < 0.01) than in the control subjects; however, the number in the respirator-supported patients was about equal to that in the controls. The number of neurons in Clarke's column in the non-respirator-supported ALS patients was not reduced, but in the respirator-supported patients they tended to disappear with time after respiratory support. These findings suggest that Clarke's column neurons are also involved primarily in the disease process in sporadic ALS. However, they may begin to disappear only after the patients require respiratory support.

Adult↗
PubMed1992

Primary leptomeningeal glioma: ultrastructural and laminin immunohistochemical studies.

We studied a case of primary leptomeningeal glioma (PLG) on the left parietal lobe of a 74-year-old woman and compared the tissue with heterotopic glial tissue from another case. The PLG tumor consisted of spindle-shaped cells with marked nuclear atypism, which tended to be arranged in a fascicular pattern, and the majority of its cells were positive for glial fibrillary acidic protein. Ultrastructural examination demonstrated that most of the tumor cells contained intermediate filaments and often junctional complexes were present on their plasma membranes. Frequently, basal lamina-like structures surrounding the tumor cell surfaces were observed. Laminin immunohistochemistry clearly demonstrated a fine network of linear positive staining around the cytoplasm and processes of the tumor cells. The ultrastructure of the heterotopic glial tissue consisted of many astrocytes partially surrounded by basal lamina. These findings strongly suggest that PLG is a distinct tumor, which arises from the heterotopic astrocytes within the subarachnoid space.

Aged↗
PubMed1992

Temporal lobe tumor demonstrating ganglioglioma and pleomorphic xanthoastrocytoma components. Case report.

The case is reported of a 16-year-old boy with a left temporal lobe tumor composed of a ganglioglioma and a pleomorphic xanthoastrocytoma. Histologically, the tumor had two different components. One component involved the cortex of the left posterior temporal lobe and showed an aggregation of neuronal cells with an astroglial stroma. Ultrastructurally, numerous dense-cored vesicles, diagnosed as ganglioglioma, were found in the neuronal cells. The other component involved the adjacent cortex and white matter of the left anterior temporal lobe and the surrounding subarachnoid space. This was composed of pleomorphic cells with many multinucleated giant cells and occasional foamy cells. Most of the tumor cells were positive for glial fibrillary acidic protein. These features correspond well to earlier descriptions of pleomorphic xanthoastrocytoma. At 24 months following total tumor extirpation, the patient is alive and has had no evidence of tumor recurrence.

Adolescent↗
PubMed1992

Syringomyelia. A neuropathological study of 18 autopsy cases.

Eighteen autopsy cases of syringomyelia were studied neuropathologically. In six cases associated with Chiari II malformation, the central canal was patent from the fourth ventricle to the syrinx, and the syrinx was simply a dilated central canal. In four cases associated with Chiari I malformation, the syrinx was irregularly shaped and communicated with the subarachnoid space at the entry zone of the posterior nerve roots. In six cases associated with spinal cord or posterior fossa tumors, the syrinx was located adjacent to the tumor tissues, and occupied the medullary gray matter or the spinal intermediate zone and the ventral part of the posterior horn. With regard to the pathogenesis of syringomyelia, we concluded that in cases associated with Chiari II malformation, vermian protrusion and direct continuity between the fourth ventricle and the syrinx were essential. In cases associated with Chiari I malformation, in addition to tonsillar protrusion, communication between the syrinx and the subarachnoid space was thought to play an important role, and in cases associated with tumors, the circulatory disturbance due to the presence of the tumors caused the syrinx.

Aged↗
PubMed1992

[Development of the fetal brain and lesion repair].

The process of lesion repair in the dramatically developing fetal brain shows a distinctive feature from that in the developed normal brain. The reason for the difference probably can be clarified by the anatomic features of the fetal brain. First, a wide extracellular space, which is necessary for the cell motility when a brain develops, preexists in the fetal brain. Secondly, it is also important that there are no cell-to-cell junctions in a fetal brain and each cell can freely locomote. Therefore, necrotized neuroblasts can be easily removed as they are "in the normal condition" by macrophages. As the astrocytes, which play an extremely important role in the developed adult brain for the repair of lesion, are still before gliogeneses or under differentiation in the fetal brain, there is little or no astrocytosis as compared with the developed brain. Therefore, the lesion repair process results in the production of a malformed brain.

Animals↗