Biomedical subjects

K Kogure

Publications and source records attributed to K Kogure.

At least 91 records · Page 5Linked to original sources

PubMed1995

Immunohistochemical localization of the low molecular weight stress protein HSP27 following focal cerebral ischemia in the rat.

We immunohistochemically investigated the induction and localization of a low-molecular weight stress protein, HSP27, in the rat brain following 1 hr of middle cerebral artery occlusion in comparison with those of HSP70. The brains were perfusion-fixed after 4 h, 1 day, 3 days, 7 days, and 14 days of reperfusion. Frozen sections were then prepared and used for immunohistochemistry. In normal brains, we observed no immunoreactivities to HSP70 and HSP27. HSP70 was localized predominantly in neurons in areas peripheral to the ischemic center after 1 day and 3 days, and in endothelial cells and perivascular cells within the ischemic center after 1 day. In contrast, HSP27 was induced in microglia in the ischemic center after 4 h, and then in reactive astrocytes distributed widely in the ipsilateral hemisphere and in part of the contralateral hemisphere after 1 through 14 days. In the center of ischemia where infarction developed, only nonspecific staining was seen. Thus, the expression patterns of HSP70 and HSP27 were quite different with regard to cell type, distribution, and time course following focal cerebral ischemia. HSP70 may be a sensitive marker of acute neuronal stress in the penumbral areas, whereas HSP27, which was most prominently induced in reactive astrocytes in periischemic and remote areas, may be a component of glial reaction to injury.

Animals↗

PubMed1995

Induction of Jun-like immunoreactivity in astrocytes in gerbil hippocampus with ischemic tolerance.

In order to evaluate the potential involvement of immediate early genes in ischemic tolerance, we examined Fos- and Jun-related protein immunoreactivity in gerbil brain. Two minutes of preconditioning ischemia or sham operation was followed by 3-min ischemia 3 days later. The animals were sacrificed after 4 h to 7 days of survival. Fos immunoreactivity was seen in dentate hilar neurons 4 h after 3-min ischemia regardless of preconditioning. Jun immunoreactivity increased in dentate granule cells 4 h after 3-min ischemia without preconditioning. Prominent Jun immunoreactivity was induced in astrocytes in the CA1 region of the gerbils with ischemic tolerance. The result suggests that Jun may contribute to the ischemic tolerance by inducing changes in gen expression in astrocytes.

Adaptation, Physiological↗

PubMed1995

Molecular evolution of a class C beta-lactamase extending its substrate specificity.

Enterobacter cloacae GC1, a clinical strain isolated in 1992 in Japan, was found to produce a chromosomal class C beta-lactamase with extended substrate specificity to oxyimino beta-lactam antibiotics, significantly differing from the known E. cloacae beta-lactamases such as the P99 beta-lactamase. The 1560 nucleotides including the GC1 beta-lactamase gene were sequenced, and the amino acid sequence of the mature enzyme comprising 364 amino acids was deduced. A comparison of the amino acid sequence with those of known E. cloacae beta-lactamases revealed the duplication of three amino acids at positions 208-213, i.e. Ala-Val-Arg-Ala-Val-Arg. This duplication was attributed to a tandem duplication of a 9-nucleotide sequence. The chimeric beta-lactamases produced by the chimeric genes from the GC1 and P99 beta-lactamase genes indicated that the extended substrate specificity is entirely attributed to the 3-amino acid insertion. Two mutant beta-lactamases were prepared from P99 beta-lactamase by site-directed mutagenesis, i.e. an Ala-Ala-Ala sequence was inserted before or after the native Ala-Val-Arg at positions 208-210. These mutant enzymes revealed that the Ala-Val-Arg located from positions 211 to 213 in the GC1 beta-lactamase are the newly inserted residues, and this phenomenon is independent of the characteristics of the amino acids inserted.

Amino Acid Sequence↗

PubMed1995

Nucleotide sequence of the 5'-flanking region of the rat type II hexokinase gene.

In a previous study, we found that the steady state transcript level of type II hexokinase was specifically and remarkably elevated in rat hepatoma AH130 cells. To determine the molecular mechanism of transcriptional control of the type II hexokinase gene, we examined the nucleotide sequence of its 5'-flanking region and analyzed putative transcription factor binding sites. We also examined the type II hexokinase promoter activity by the chloramphenicol acetyltransferase (CAT) assay.

Amino Acid Sequence↗

PubMed1995

Alteration of [3H]hemicholinium-3 binding in the post-ischaemic gerbil brain.

To determine whether presynaptic sites are resistant to cerebral ischaemia, we investigated the postischaemic alteration in [3H]hemicholinium-3 binding as a sensitive marker of presynaptic cholinergic terminals in the gerbil brain between 1 h and 7 days after recirculation using receptor autoradiography. Transient ischaemia was induced for 10 min. [3H]hemicholinium-3 binding was unchanged in the frontal cortex, striatum and hippocampus throughout the recirculation periods. Our histological study revealed conspicuous neuronal damage in the frontal cortex, striatum, hippocampal CA1 sector and hippocampal CA3 sector after ischaemia. The present study demonstrates that presynaptic sites in selectively vulnerable areas can maintain their structural components although postsynaptic neurones are clearly degenerated. Thus our findings support the hypothesis that presynaptic sites are particularly resistant to ischaemia, but postsynaptic sites are vulnerable.

Animals↗

PubMed1995

Early immunohistochemical changes of microtubule based motor proteins in gerbil hippocampus after transient ischemia.

Changes of immunoreactivities for microtubule based motor proteins, kinesin and cytoplasmic dynein, and non-motor protein, microtubule associated protein (MAP) 2 were investigated in gerbil hippocampus after transient ischemia. The immunoreactivities for kinesin showed a progressive decrease in hippocampal CA1 cells from 8 h after transient 5 or 15 min of ischemia that is lethal to the CA1 cells, while it showed no change after 2 min of ischemia that is non-lethal to the cells. The immunoreactivities for cytoplasmic dynein showed a decrease from 3 or 1 h of reperfusion in the CA1 cells after 5 or 15 min of ischemia, respectively. In contrast, the immunoreactivity for MAP2 remained normal until 2 days in the CA1 cells after 5 min of ischemia. These results showed an early changes of microtubule based motor proteins, such as kinesin and cytoplasmic dynein in vulnerable CA1 neurons. These changes may affect the mitochondrial shuttle system between neuronal cell body and the peripheries such as axon terminal and dendrites. This early disturbance may cause a failure to obtain newly synthesized nuclear encoded mitochondrial protein, and result in mitochondrial dysfunctions and the subsequent cell death.

Animals↗

PubMed1995

Rolipram, a cyclic AMP-selective phosphodiesterase inhibitor, reduces neuronal damage following cerebral ischemia in the gerbil.

We examined the effects of rolipram, a cyclic AMP-selective phosphodiesterase inhibitor, on cerebral ischemia-induced neuronal damage in Mongolian gerbils. Transient forebrain ischemia was induced by 3-min occlusion of bilateral common carotid arteries. Rolipram, at a dose of 0.3 or 3 mg/kg, was injected i.p. 30 min before ischemia. Histopathological observations showed that neuronal damage to the hippocampal CA1 subfield, which was seen 7 days after ischemia in vehicle-treated animals, was reduced in animals treated with the higher dose of rolipram.

Animals↗

PubMed1995

A single intraportal administration of follistatin accelerates liver regeneration in partially hepatectomized rats.

BACKGROUND/AIMS: Activin A is an autocrine negative regulator of DNA synthesis in rat hepatocytes and is expressed in remnant liver after partial hepatectomy. To determine the role of activin A in liver regeneration, the effects of exogenous follistatin, which blocks the action of activin A, were examined. METHODS: Human recombinant follistatin was infused into the portal vein immediately after 70% hepatectomy. Changes in body weight, remnant liver weight, liver regeneration rate, and nuclear bromodeoxyuridine labeling were measured. RESULTS: In control rats, nuclear labeling was observed at 24 hours and peaked at 36 hours after the hepatectomy. In follistatin-treated rats, nuclear labeling was first observed after 18 hours and was significantly (P < 0.05) greater than that in control rats at 24 hours. In follistatin-treated rats, both remnant liver weight and liver regeneration rate were significantly greater at 120 hours. Serum concentrations of albumin and glucose remained reduced for up to 120 hours in control rats but recovered in follistatin-treated rats. CONCLUSIONS: A single administration of follistatin accelerates the initial round of DNA synthesis after partial hepatectomy. Activin A produced in remnant liver may exert tonic inhibitory effect on liver regeneration. Follistatin may be useful as a potential therapeutic agent to promote liver regeneration.

Activins↗

PubMed1995

Induction of heparin-binding growth-associated molecule expression in reactive astrocytes following hippocampal neuronal injury.

Heparin-binding growth-associated molecule is a potent neurotrophic factor. To obtain a better understanding of its role in the central nervous system, we studied the changes of its expression in adult rat brain after two types of neuronal injury. In the control hippocampus, expression of heparin-binding growth-associated molecule messenger RNA was confined to CA1 pyramidal neurons and some hilar cells. Following transient forebrain ischaemia, the messenger RNA expression decreased within the first two days. On day 4, however, both the messenger RNA level and the number of expression-positive cells markedly increased in the CA1 subfield, where the selective neuronal losses were seen following ischaemia. Double-staining with a heparin-binding growth-associated molecule complementary RNA probe and an anti-glial fibrillary acidic protein antibody revealed that most of the expressing cells were reactive astrocytes. Moreover, the protein induction of heparin-binding growth-associated molecule after neuronal injury was demonstrated by immunohistochemistry using the affinity-purified antibodies. This molecule was also induced after intraventricular kainate injection, which is known to cause selective pyramidal cell necrosis in the CA3 region. Four days after the insult, the number of cells expressing the messenger RNA prominently increased in the CA3 subfield ipsilateral to the injection. As observed after the ischaemic insult, most of the expression-positive cells were identified as astrocytes. The data presented here suggest that heparin-binding growth-associated molecule, produced by the reactive astrocytes, may play important roles in the repair process after neuronal injury.

Animals↗

PubMed1995

An immunohistochemical study of heat shock protein-27 in the hippocampus in a gerbil model of cerebral ischemia and ischemic tolerance.

Preconditioning of the gerbil brain with a 2-min period of sublethal ischemia protects against neuronal damage following a subsequent 3-min period of ischemia which normally damages CA1 neurons of the hippocampus (ischemic tolerance). In this study, we investigated the role of a small stress protein, heat shock protein-27, in the induction of ischemic tolerance. For this purpose, we used immunohistochemistry with an antibody against heat shock protein-27. Normal hippocampus contained very low levels of heat shock protein-27. The preconditioning ischemia for 2 min caused little changes in the heat shock protein-27 immunostaining in CA1 neurons but an increase in heat shock protein-27 immunostaining in a small number of astrocytes in the CA3 region and in many astrocytes in the dentate hilus. The second ischemia for 3 min caused no specific changes in heat shock protein-27 immunostaining in CA1 neurons both with and without tolerance in early reperfusion periods. After seven days, destruction of CA1 neurons occurred in animals without preconditioning and reactive astrocytes were intensely immunostained for heat shock protein-27. An intense heat shock protein-27 immunostaining was also seen in astrocytes in the dentate hilus after the second ischemia in both groups. Thus, we observed no temporal correlation between the induction of heat shock protein-27 and the manifestation of ischemic tolerance in the CA1 neurons. Most intense heat shock protein-27 immunostaining was observed in reactive astrocytes that accumulated in the damaged CA1 region and dentate hilus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Facilitated recovery from postischemic suppression of protein synthesis in the gerbil brain with ischemic tolerance.

Preconditioning of the gerbil brain with a 2-min period of sublethal ischemia followed by 4 days of reperfusion protects against neuronal damage following a subsequent 3-min period of ischemia, which normally destroys pyramidal neurons in the CA1 region of the hippocampus. To clarify the role of protein synthesis in this ischemic tolerance phenomenon, we performed an autoradiographic analysis with [14C]leucine at 4 h, 24 h, and 48 h after 3 min of ischemia with and without preconditioning. General protein synthesis in the CA1 region was severely suppressed after 4 h in both groups. The protein synthesis in CA1 partially recovered after 24 h and fully recovered after 48 h in animals with preconditioning, but never recovered in animals without preconditioning. Protein synthesis in the neocortex and the striatum was suppressed in the early reperfusion periods only in animals without preconditioning. The results show that the ischemic tolerance is closely related to the facilitated recovery from suppressed protein synthesis in the brain after ischemia.

Adaptation, Physiological↗

PubMed1995

Calcium deposits in the thalamus following repeated cerebral ischemia and long-term survival in the gerbil.

We investigated the long-term changes in the gerbil brain following three episodes of 2-min forebrain ischemia at 1-h intervals in comparison with a 6-min period of ischemia. The animals were sacrificed after 1 month and 6 months. Following either ischemic insult, the hippocampal CA1 region showed a loss of pyramidal neurons together with a diffuse calcium accumulation as shown by alizarin red S staining. Three 2-min ischemic insults additionally produced neuronal damage in the striatum and thalamus. The thalamic damage was accompanied by an accumulation of small calcium granules after 1 month and large calcium concretions after 6 months. Calcium staining in the striatum was weak. Thus, the thalamic neuronal damage was accompanied by an active process of calcification, which has not been described in experimental cerebral ischemia models. The observations show that repeated ischemic insults produce different long-term effects in different brain regions.

Animals↗

PubMed1995

Role of neutrophils in radical production during ischemia and reperfusion of the rat brain: effect of neutrophil depletion on extracellular ascorbyl radical formation.

A growing body of experimental data indicate that oxygen radicals may mediate the brain injury during ischemia-reperfusion. One potential source of oxygen radicals is activated neutrophils. To study the role of neutrophils in radical production during cerebral ischemia-reperfusion, we evaluated the effects of depletion of circulating neutrophils by administration of an anti-neutrophil monoclonal antibody (RP3) on radical formation in rats with 1-h middle cerebral artery (MCA) occlusion. In the present study, we employed a new electron spin resonance method coupled with brain microdialysis. The method uses the endogenous ascorbyl radical (AR) concentration as a marker of oxygen radicals and requires no spin-trapping agents. In the vehicle controls, extracellular AR decreased during MCA occlusion. After reperfusion, AR significantly increased at 30 min and 1 h, returned to near basal level until 2 h, and increased again at 24 h after reperfusion. In the rats treated with RP3, AR decreased during MCA occlusion to the same extent as in the vehicle control. However, RP3 treatment completely inhibited the increase in extracellular AR after reperfusion. RP3 treatment exerted no effect on the changes in extracellular ascorbate or tissue PO2 throughout the experimental period. In conclusion, neutrophils are a major source of oxygen radicals during reperfusion after focal cerebral ischemia.

Animals↗

PubMed1995

Immunohistochemical localization of superoxide dismutase in the hippocampus following ischemia in a gerbil model of ischemic tolerance.

Pretreatment of the gerbil brain with a 2-min period of sublethal ischemia protects against neuronal damage following a subsequent 3-min period of ischemia, which normally destroys pyramidal neurons in the CA1 region of the hippocampus. To clarify the role of superoxide dismutase (SOD) in this ischemic tolerance, we immunohistochemically investigated the alterations in copper-zinc SOD (CuZnSOD) and manganese SOD (Mn-SOD) in the gerbil hippocampus following 3-min ischemia with or without the first mild ischemia. Normal hippocampus showed an intense CuZnSOD immunostaining in pyramidal neurons but relatively less MnSOD immunostaining. MnSOD, but not CuZnSOD, immunoreactivity increased after the first ischemia. Both CuZnSOD and MnSOD immunoreactivities decreased throughout the hippocampus 4 h after 3 min of ischemia both with and without the first ischemia. The immunostaining recovered in resistant regions (CA3 and dentate gyrus) after 1 day in both groups and in the pretreated CA1 after 2 days. Without pretreatment, however, the immunostaining never recovered in the vulnerable CA1 region. The results suggest that ischemic tolerance is induced in part by enhanced synthesis of MnSOD in the tolerance-acquired hippocampus. Both CuZnSOD and MnSOD immunoreactivities decreased after the second ischemia even in the pretreated hippocampus in the early reperfusion periods, but ischemic tolerance facilitated the recovery from the postischemic reductions in SOD immunoreactivity.

Animals↗

PubMed1995

Transient increase of cytokine-induced neutrophil chemoattractant, a member of the interleukin-8 family, in ischemic brain areas after focal ischemia in rats.

BACKGROUND AND PURPOSE: We have indicated that neutrophils play an important role in cerebral ischemia-reperfusion injury. Neutrophils are also known to adhere to the endothelial wall through adhesion molecules and to infiltrate into the tissue, and this neutrophilic invasion correlates with the concentration gradient of chemotactic factors. The aim of the present study was to evaluate the role of cytokine-induced neutrophil chemoattractant (CINC) on brain damage in rats from transient ischemia. METHODS: The brain water content was measured to evaluate postischemic brain injury in rats with 60 minutes of middle cerebral artery occlusion with perfusion. An enzyme-linked immunosorbent assay was used to evaluate the blood and brain concentrations of CINC, and enzymatic and histological techniques were used to measure the neutrophilic infiltration into the brain. RESULTS: The increase of water content was first observed at 6 hours after reperfusion, after which this increase was gradual, with brain edema peaking from 24 to 48 hours after reperfusion. Neutrophilic infiltration into the parenchyma and myeloperoxidase activity were first noted 12 hours after reperfusion, after which a marked increase occurred from 24 to 48 hours after reperfusion. In the ischemic brain areas, CINC was first detected at 3 hours after reperfusion. The CINC level peaked at 12 hours after reperfusion (9.15 +/- 0.45 ng/g wet wt, n = 5 and then gradually reduced from 24 to 48 hours after reperfusion (5.35 +/- 0.95 ng/g wet wt, n = 5, and 1.25 +/- 0.10 ng/g wet wt, n = 5, respectively). Interestingly, the serum CINC concentration was transiently elevated from 3 to 6 hours after reperfusion. No CINC production was detected in the brain of rats subjected to 60 minutes of ischemia without reperfusion. CONCLUSIONS: A marked increase in CINC concentration was detected in brain and serum during early reperfusion. This suggests that the time course of CINC production precedes brain edema formation and neutrophilic infiltration. It thus appears that CINC may play an important role in neutrophilic infiltration in ischemic lesion and in brain edema formation after ischemia-reperfusion injury.

Animals↗

PubMed1995

Interleukin-1 as a pathogenetic mediator of ischemic brain damage in rats.

BACKGROUND AND PURPOSE: It has been suggested that interleukin-1 (IL-1) is a potent inflammatory mediator and that it is synthesized and secreted into the brain parenchyma. The aim of the present study is to evaluate the contribution of IL-1 to brain edema formation after focal brain ischemia. METHODS: The brain water content was measured to evaluate postischemic brain injury in rats after 60 minutes of middle cerebral artery occlusion and reperfusion. The effects of exogenous application of recombinant human interleukin-1 beta (rhIL-1 beta), anti-interleukin-1 beta neutralizing antibodies (anti-IL-1 beta), and the IL-1 blocker zinc protoporphyrin (ZnPP) on brain water content were observed, and histological technique was used to measure the infarction size and number of inflammatory cells infiltrated into the brain. RESULTS: Transient ischemia induced marked increase of brain water content, necrosis, and neutrophilic infiltration in the cortex perfused by the middle cerebral artery and the dorsal and ventral areas of the caudate putamen. Injection of rhIL-1 beta into the left lateral ventricle immediately after reperfusion markedly enhanced ischemic brain edema formation in these three areas in a dose-dependent manner (88.4 +/- 0.7% and 86.6 +/- 0.4% in the dorsal and ventral parts of the caudate putamen, respectively, in rats treated with 10 ng rhIL-1 beta; P < .01). rhIL-1 beta also increased the size of the brain infarction, and it tended to increase the number of infiltrating neutrophils in ischemic areas and the number of neutrophils adherent to the endothelium. In contrast, administration of anti-IL-1 beta and ZnPP into the left cerebral ventricle attenuated the postischemic increase of brain water content and decreased the size of brain infarction (83.5 +/- 2.0% and 79.9 +/- 2.0% in the dorsal and ventral parts of the caudate putamen, respectively, in rats treated with 10 micrograms anti-IL-1 beta; P < .01). The number of neutrophils that infiltrated into ischemic areas also tended to decrease with anti-IL-1 beta or ZnPP treatment. CONCLUSIONS: Application of rhIL-1 beta augmented the increase of brain water content, and application of anti-IL-1 beta depressed the increase of water content. These results tended to correlate with the neutrophilic infiltration into the parenchyma. It thus appears that IL-1 beta may play an important role in ischemic brain damage after reperfusion.

Animals↗

PubMed1995

Ischemic delayed neuronal death. A mitochondrial hypothesis.

BACKGROUND: A brief period of global brain ischemia causes cell death in hippocampal CA1 pyramidal neurons days after reperfusion in rodents and humans. Other neurons are much less vulnerable. This phenomenon is commonly referred to as delayed neuronal death, but the cause has not been fully understood although many mechanisms have been proposed. SUMMARY OF REVIEW: Hippocampal CA1 neuronal death usually occurs 3 to 4 days after an initial ischemic insult. Such a delay is essential for the mechanism of this type of cell death. Previous hypotheses have not well explained the reason for the delay and the exact mechanism of the cell death, but a disturbance of mitochondrial gene expression could be a possibility. Reductions of mitochondrial RNA level and the activity of a mitochondrial protein, encoded partly by mitochondrial DNA, occurred exclusively in CA1 neurons at the early stage of reperfusion and were aggravated over time. In contrast, the activity of a nuclear DNA-encoded mitochondrial enzyme and the level of mitochondrial DNA remained intact in CA1 cells until death. Immunohistochemical staining for cytoplasmic dynein and kinesin, which are involved in the shuttle movement of mitochondria between cell body and the periphery, also showed early and progressive decreases after ischemia, and the decreases were found exclusively in the vulnerable CA1 subfield. CONCLUSIONS: A disturbance of mitochondrial DNA expression may be caused by dysfunction of the mitochondrial shuttle system and could cause progressive failure of energy production of CA1 neurons that eventually results in cell death. Thus, the mitochondrial hypothesis could provide a new and exciting potential for elucidating the mechanism of the delayed neuronal death of hippocampal CA1 neurons.

Animals↗

PubMed1995

Spontaneous transfer of viral protein from membrane of influenza virus-infected cells to liposomes is dependent on the diameter of receiver.

Spontaneous transfer of protein from either influenza virus-infected or uninfected cells to dimyristoylphosphatidylcholine (DMPC) liposomes was examined. The amount of transferred protein of liposomes incubated with influenza virus-infected cells (I-lipo) was more than that of liposomes incubated with uninfected cells (U-lipo). The ratio of the amount of spontaneous transferred protein of I-lipo to that of U-lipo increased in proportion to the diameter of liposomes except for small unilamellar vesicles.

Animals↗