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Biomedical subjects

T Mabuchi

Publications and source records attributed to T Mabuchi.

At least 19 recordsLinked to original sources

Vascular matrix adhesion and the blood-brain barrier.

The integrity of the cerebral microvasculature depends on the interaction between its component cells and the extracellular matrix, as well as reorganized cell-cell interactions. In the central nervous system, matrix adhesion receptors are expressed in the microvasculature and by neurons and their supporting glial cells. Cells within cerebral microvessels express both the integrin and dystroglycan families of matrix adhesion receptors. However, the functional significance of these receptors is only now being explored. Endothelial cells and astrocytes within cerebral capillaries co-operate to generate and maintain the basal lamina and the unique barrier functions of the endothelium. Integrins and the dystroglycan complex are found on the matrix-proximate faces of both endothelial cells and astrocyte end-feet. Pericytes rest against the basal lamina. In the extravascular compartment, select integrins are expressed on neurons, microglial cells and oligodendroglia. Significant alterations in both cellular adhesion receptors and their matrix ligands occur during focal cerebral ischaemia, which support their functional significance in the normal state. We propose that matrix adhesion receptors are essential for the maintenance of the integrity of the blood-brain permeability barrier and that modulation of these receptors contributes to alterations in the barrier during brain injury.

Animals↗

PRKAR1A gene mutation in patients with cardiac myxoma.

BACKGROUND: PRKAR1A gene encodes the type 1A regulatory subunit of protein kinase A. The mutation of this gene causes Carney complex which is an autosomal dominant multiple neoplasia syndrome characterized by spotty pigmentations, endocrine overactivity and cardiac myxoma. We hypothesized that cardiac myxoma may be associated with PRKAR1A gene mutation and determined whether mutation in the PRKAR1A gene is the cause of familial and sporadic cardiac myxoma. METHODS: We studied seven patients (three males and four females) with cardiac myxoma. Two of them had familial cardiac myxoma complicated with Carney complex. The other five patients were characterized as sporadic cardiac myxomas. We analyzed the PRKAR1A gene of all patients by the polymerase chain reaction (PCR)-single-strand conformation method, followed with direct sequence analysis. RESULTS: We identified a novel mutation (494delTG) in exon 4A of the PRKAR1A gene in the patients with Carney complex. A 16-year-old proband had a left atrial myxoma, pituitary adenoma and skin pigmentation. His father also had left atrial myxoma and skin pigmentation. In contrast, no mutations in the PRKAR1A gene were identified in the other five patients with sporadic cardiac myxomas. CONCLUSIONS: These results suggest that mutation of the PRKAR1A gene may be associated with familial cardiac myxoma in Carney complex but may not be associated with sporadic cardiac myxoma.

Adolescent↗

Involvement of Rho-kinase in inflammatory and neuropathic pain through phosphorylation of myristoylated alanine-rich C-kinase substrate (MARCKS).

Myristoylated alanine-rich C-kinase substrate (MARCKS) is a major in vivo substrate for protein kinase C in the brain and has been implicated in cellular processes associated with cytoskeletal restructuring such as synaptic trafficking and neurotransmitter release. A phosphorylation-site specific antibody against Ser159-phospho-MARCKS (pS159-Mar-Ab) revealed that MARCKS is phosphorylated at Ser159 by Rho-kinase and that its phosphorylation is inhibited by the Rho-kinase specific inhibitor H-1152. Since the function of MARCKS is regulated by phosphorylation at multiple sites, here we examined the involvement of Rho-kinase in relation to phosphorylation of MARCKS at Ser159 in inflammatory and neuropathic pain by H-1152. When intrathecally administered 10 min before s.c. injection of formalin, H-1152 at 10 and 100 ng attenuated the second-phase, but not the first-phase, pain-like behaviors in the formalin test. Neuropathic pain induced by selective L5 spinal nerve transection was also relieved by intrathecal injection of H-1152. Nitric oxide synthase activity visualized by NADPH diaphorase histochemistry increased in the superficial layer of the spinal cord 30 min after formalin injection and 7 days after nerve transection, which were blocked by H-1152. Phosphorylation of MARCKS at Ser159 was detected in the spinal cord by pS159-Mar-Ab and the level of phosphorylation increased in the superficial layer after nerve transection. In contrast, immunoreactivities of neuronal nitric oxide synthase and MARCKS did not change significantly in the spinal cord before and after nerve transection. Taken together, the present study demonstrates that Rho-kinase is involved in inflammatory pain and the maintenance of neuropathic pain through phosphorylation of MARCKS at Ser159.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Long-term body weight variability is associated with elevated C-reactive protein independent of current body mass index among Japanese men.

OBJECTIVE: To elucidate the effect of long-term weight variability on C-reactive protein (CRP) levels. DESIGN: Cross-sectional study of the circulating CRP. SUBJECTS: A total of 637 Japanese men aged 40-49 y in1997. MEASUREMENTS: Serum CRP levels, body mass index in 1997 (current BMI), the slope of weight on age (weight-slope) representing an individual's weight trend of direction and magnitude, and the root mean square error around the slope of weight on age (weight-RMSE) representing the weight fluctuation magnitude, as calculated by a simple linear regression model in which each value of the subject's five actual weights (aged 20, 25, 30 y, five years ago, and current) was a dependent variable and the subject's ages independent variables. RESULTS: After adjustment for age and confounders, including smoking and health status, the odds ratios of elevated CRP (> or =0.06 mg/dl) were 1.83 (95% CI: 1.25-2.69), 2.63 (1.69-4.11), and 10.31 (2.17-48.98) for upper normal-weight (BMI: 22-<25 kg/m(2)), overweight (25-<30), and obese (> or =30) persons, respectively, compared with lower normal-weight persons (18.5-<22). Adjusting for age, confounders, and current BMI, weight-slope was positively associated with CRP level especially among subjects with BMI> or =25 kg/m(2) (trend P<0.01), and weight-RMSE was positively associated with CRP level particularly among subjects with BMI <25 kg/m(2) (trend P<0.05). CONCLUSION: Our results suggest a state of low-grade systemic inflammation not only in overweight and obese persons, but also in normal-weight persons with large weight fluctuation, possibly explaining in part the positive association between weight fluctuation and CVD.

Adipose Tissue↗

Chloride transport in microperfused interlobular ducts isolated from guinea-pig pancreas.

Isolated interlobular ducts from the guinea-pig pancreas secrete a HCO3--rich fluid in response to secretin. To determine the role of Cl- transporters in this process, intracellular Cl- concentration ([Cl-]i) was measured in ducts loaded with the Cl--sensitive fluoroprobe, 6-methoxy-N-ethylquinolinium chloride (MEQ). [Cl-]i decreased when the luminal Cl- concentration was reduced. This effect was stimulated by forskolin, was not dependent on HCO3- and was not inhibited by application of the anion channel/transporter inhibitor H2DIDS to the luminal membrane. It is therefore attributed to a cAMP-stimulated Cl- conductance, probably the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. [Cl-]i also decreased when the basolateral Cl- concentration was reduced. This effect was not stimulated by forskolin, was largely dependent on HCO3- and was inhibited by basolateral H2DIDS. It is therefore mediated mainly by Cl-/HCO3- exchange. With high Cl- and low HCO3- concentrations in the lumen, steady-state [Cl-]i was 25-35 mM in unstimulated cells. Stimulation with forskolin caused [Cl-]i to increase by approximately 4 mM due to activation of the luminal anion exchanger. With low Cl- and high HCO3- concentrations in the lumen to simulate physiological conditions, steady-state [Cl-]i was 10-15 mM in unstimulated cells. Upon stimulation with forskolin, [Cl-]i fell to approximately 7 mM due to increased Cl- efflux via the luminal conductance. We conclude that, during stimulation under physiological conditions, [Cl-]i decreases to very low levels in guinea-pig pancreatic duct cells, largely as a result of the limited capacity of the basolateral transporters for Cl- uptake. The resulting lack of competition from intracellular Cl- may therefore favour HCO3- secretion via anion conductances in the luminal membrane, possibly CFTR.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

Phosphorylation of cAMP response element-binding protein in hippocampal neurons as a protective response after exposure to glutamate in vitro and ischemia in vivo.

Although accumulating evidence indicates that cAMP response element-binding protein (CREB) phosphorylation mediates not only synaptic plasticity but also survival of certain neurons, it remains uncertain whether CREB phosphorylation induced after metabolic insult leads to CRE-mediated gene transcription and is involved in cell survival or not. In the present study, we clarified that (1) CREB phosphorylation and ischemic tolerance induced after preconditioning ischemia in the hippocampal neurons was abolished by MK801 administration in gerbil global ischemia model, (2) CREB phosphorylation induced after exposure to glutamate in cultured neurons was inhibited by removal of extracellular calcium, by MK801 and by an inhibitor of calcium-calmodulin-dependent protein kinase (CaMK) II and IV, (3) inhibitor of CaMK II-IV or CRE-decoy oligonucleotide suppressed upregulation of BCL-2 expression and accelerated neuronal damage after exposure to glutamate, and (4) CREB phosphorylation induced in the hippocampal neurons after ischemia and in cultured neurons after exposure to glutamate was followed by CRE-mediated gene transcription in transgenic mice with a CRE-LacZ reporter. Our results suggest that CREB phosphorylation in neurons after ischemia and exposure to glutamate is induced by NMDA receptor-gated calcium influx and subsequent activation of CaMK II-IV and that CREB phosphorylation after metabolic stress might show a neuroprotective response through CRE-mediated gene induction.

Animals↗

Acute increases in plasma oxidized low-density lipoprotein immediately after percutaneous transluminal coronary angioplasty.

To investigate the acute changes in plasma oxidized low-density lipoprotein before and immediately after coronary angioplasty, we studied 132 consecutive patients who successfully underwent this procedure. Plasma oxidized low-density lipoprotein levels were significantly increased immediately after coronary angioplasty in patients with stable angina pectoris as well as in those with acute coronary syndromes.

Aged↗

Coronary lesion morphology and prognosis in young males with myocardial infarction with or without familial hypercholesterolemia.

The present study examined the angiographic characteristics and prognosis of young males under 40 years of age with acute myocardial infarction (AMI) and familial hypercholesterolemia (FH). The study group was divided into an FH group (n=16) and a non-FH group (n=27). Lesion morphology was classified as complex or smooth. Overall 36 patients were followed up for an average of 9.4 years. The frequency of angiographic normal or nonobstructive culprit lesions was significantly higher in the non-FH group (p<0.01). In contrast, the incidence of complex or totally occlusive lesions was higher in the FH group (p<0.01). At 10-year follow-up, survival rates from cardiac death (FH 85% vs non-FH 100%, p=0.06), from AMI (FH 43% vs non-FH 80%, p<0.05), and from any ischemic event at a new lesion (FH 9% vs non-FH 67%, p<0.01) were all reduced in the FH group. These results suggest that the mechanism of AMI in young male patients with FH differs from that in similar aged patients without FH, and that the overall prognosis of these patients is less favorable.

Adult↗

Regional difference of neuronal vulnerability in the murine hippocampus after transient forebrain ischemia.

We have investigated the regional difference of neuronal vulnerability within the hippocampus in the C57BL/6 strain mice after forebrain ischemia. Both common carotid arteries of fifty mice were occluded for 12 min and the mouse brain was examined with cresyl violet staining. The CA4 sector was found to be the most vulnerable within the hippocampus. The CA2 and the medial CA1 sector was the 2nd and 3rd most vulnerable regions. However, The lateral part of the CA1 sector, CA3 sector and the dentate gyrus were resistant to ischemic insult.

Animals↗

ASC1/RAS2 suppresses the growth defect on glycerol caused by the atp1-2 mutation in the yeast Saccharomyces cerevisiae.

To better define the regulatory role of the F(1)-ATPase alpha-subunit in the catalytic cycle of the ATP synthase complex, we isolated suppressors of mutations occurring in ATP1, the gene for the alpha-subunit in Saccharomyces cerevisiae. First, two atp1 mutations (atp1-1 and atp1-2) were characterized that prevent the growth of yeast on non-fermentable carbon sources. Both mutants contained full-length F(1)alpha-subunit proteins in mitochondria, but in lower amounts than that in the parental strain. Both mutants exhibited barely measurable F(1)-ATPase activity. The primary mutations in atp1-1 and atp1-2 were identified as Thr(383) --> Ile and Gly(291) --> Asp, respectively. From recent structural data, position 383 lies within the catalytic site. Position 291 is located near the region affecting subunit-subunit interaction with the F(1)beta-subunit. An unlinked suppressor gene, ASC1 (alpha-subunit complementing) of the atp1-2 mutation (Gly(291) --> Asp) restored the growth defect phenotype on glycerol, but did not suppress either atp1-1 or the deletion mutant Deltaatp1. Sequence analysis revealed that ASC1 was allelic with RAS2, a G-protein growth regulator. The introduction of ASC1/RAS2 into the atp1-2 mutant increased the F(1)-ATPase enzyme activity in this mutant when the transformant was grown on glycerol. The possible mechanisms of ASC1/RAS2 suppression of atp1-2 are discussed; we suggest that RAS2 is part of the regulatory circuit involved in the control of F(1)-ATPase subunit levels in mitochondria.

Adaptor Proteins, Signal Transducing↗

Characterization of the selective staining of DNA on gels using two fluorochromes.

Ethidium bromide (EB) and 4'-6-diamidino-2-phenylindole (DAPI) are both well-known fluorochromes for detecting DNA fragments. EB binds to DNA by intercalation and DAPI binds in the DNA minor groove. We previously developed a staining method using both EB and DAPI that is selective for AT-rich DNA fragments. Using this double-staining method, AT-rich DNA fragments are visualized as bluish-white fluorescent bands. To further characterize this method, a series of synthetic DNA fragments were designed with systematic variations in the length, AT content, and DNA sequence pattern. The staining properties of these fragments were determined in the presence of DAPI and EB, and the following results were obtained. (i) In a series of fragments with three AT base pairs followed by one GC base pair, the stained DNA fragments exhibited different fluorescent colors and varied from bluish (more DAPI staining) to pinkish (less DAPI staining) in the order 5'-AAA-3', 5'-AAT-3', 5'-ATA-3', 5'-TTA-3'. (ii) In fragments with constant AT content, the blue fluorescent color increased with increasing number of A (or T) nucleotides, due to increased DAPI binding. The blue color was saturated when the number of A (or T) nucleotides was 12 or greater. (iii) The fluorescent color of the stained DNA fragments changed in the order of red-orange, pink, pinkish-white, white, bluish-white, blue as the AT content increased from 0 to 100%. Thus, the fluorescent color of DNA fragments stained with DAPI and EB depends on base composition and nucleotide sequence, suggesting that individual stained DNA fragments may have characteristic and specific fluorescent colors. The fluorescent color emitted by specific stained DNA fragments in the presence of EB and DAPI can be analyzed with a high degree of sensitivity and resolution using the XYZ colorimetric system.

Base Pairing↗

Extended neuronal protection induced after sublethal ischemia adjacent to the area with delayed neuronal death.

In the present study, we investigated whether neurons adjacent to an ischemic lesion acquire tolerance against subsequent ischemia or not. We initially used unilateral hemispheric ischemia for 3 min in gerbils to produce an ischemic lesion confined to the unilateral CA1 sector, and the presence of tolerance was examined in the adjacent CA3 sector through transient global ischemia by occlusion of both common carotid arteries. Attenuation of neuronal damage was clearly observed in neurons in the CA3 sector adjacent to the ischemic lesion in the CA1 sector. The phenomenon lasted for up to two weeks after the initial hemispheric ischemia, but was no longer present two months later. Reactive astrocytes as identified by the presence of glial fibrillary acidic protein were visible in the CA3 hippocampus four days and two weeks after hemispheric ischemia, but they were scarce two months later. Expression of heat shock protein 72 in the CA3 neurons was observed four days after hemispheric ischemia, but the reaction returned to the control level two weeks later. In conclusion, the present study showed that tolerance in the neurons adjacent to an ischemic lesion could be sustained at least for two weeks, and raised the possibility that reactive astrocytes might contribute to the extended tolerance in neurons.

Animals↗

Exercise-induced ST-segment depression and systolic dysfunction in patients with nonobstructive hypertrophic cardiomyopathy.

BACKGROUND: ST-segment depression is common in patients with hypertrophic cardiomyopathy (HCM). However, it is not clear whether exercise-induced ST-segment depression in patients with HCM and patent coronary arteries is associated with changes in left ventricular function. METHODS: Left ventricular function was continuously evaluated in 53 patients with nonobstructive HCM during supine ergometer exercise with a radionuclide ventricular function monitor equipped with a cadmium telluride detector. On the basis of the ST-segment changes during exercise, the patients were divided into 2 groups: group N had no ST-segment depression, and group D had >/=0.1 mV ST-segment depression. RESULTS: Exercise duration, blood pressure, heart rate, and rate-pressure product during exercise did not differ between the 2 groups. End-diastolic volume at rest and at peak exercise did not differ between groups D and N. In contrast, the end-systolic volume in group N decreased during exercise, whereas in group D it increased. As a result, the left ventricular ejection fraction in group D decreased from 70% +/- 7% to 59% +/- 15% (P <.0001), whereas ejection fraction in group N increased from 65% +/- 8% to 71% +/- 11% (P =.0002). There was a strong correlation between exercise-induced ST-segment depression and changes in ejection fraction from rest to peak exercise (P <.0001). CONCLUSIONS: These results suggest that the exercise-induced ST-segment depression seen in patients with nonobstructive HCM is associated with systolic dysfunction during exercise.

Adolescent↗

Cardiac dysfunction and long-term prognosis in patients with nonobstructive hypertrophic cardiomyopathy and abnormal (123)I-15- (p-Iodophenyl)-3(R,S)-methylpentadecanoic acid myocardial scintigraphy.

To evaluate the relationship between myocardial scintigraphic abnormalities based on (123)I-radioiodinated 15-(p-iodophenyl)-3(R, S)-methylpentadecanoic acid (BMIPP) uptake and cardiac function and the relationship between these abnormalities and long-term prognosis in patients with hypertrophic cardiomyopathy (HCM), 27 patients with nonobstructive HCM underwent BMIPP myocardial scintigraphic study, echocardiography, and exercise radionuclide study. Based on the extent of BMIPP scintigraphic defects, the patients were divided into two groups: Group A (n = 19) patients had no or small defects, and group B (n = 8) patients had moderate to large defects. Cardiac events were recorded over an average period of 64 months. The left ventricular end-diastolic and end-systolic dimensions were significantly greater in group B than in group A. The fractional shortening in group B was less than in group A (p = 0.0002). The BMIPP score and fractional shortening at rest correlated significantly (p < 0.05). The BMIPP score and the change in ejection fraction between rest and peak exercise correlated significantly (p < 0.05). While only 1 cardiac event occurred in the 19 patients in group A during a mean follow-up period of 64 months, 6 cardiac events occurred in the 8 patients in group B. The 84-month event-free survival rate was 94.4% in group A and 14.6% in group B (p < 0.01). These results suggest that patients with HCM and moderate to large defects as assessed by BMIPP myocardial scintigraphy have decreased cardiac function and a poor prognosis.

Adult↗

Contribution of microglia/macrophages to expansion of infarction and response of oligodendrocytes after focal cerebral ischemia in rats.

BACKGROUND AND PURPOSE: The purpose of this study was (1) to examine the contribution of microglia and macrophages with their interleukin-1beta production and (2) to assess the vulnerability and response of oligodendrocytes in cerebral infarction. METHODS: Male Wistar rats were subjected to permanent occlusion of the left middle cerebral artery. Expansion of ischemic infarction and response of oligodendrocytes were investigated together with accumulation of inflammatory cells, production of interleukin-1beta, and disruption of the blood-brain barrier. Apoptotic cell death was inferred from fragmented DNA and the expression of proapoptotic Bax protein. RESULTS: During expansion of infarction, amoeboid microglia and extravasation of serum albumin were observed not only in the infarcted area but also in the adjacent surviving area, whereas macrophages accumulated along the boundary and granulocytes migrated into the center of the infarction. Both amoeboid microglia and macrophages produced interleukin-1beta, an inflammatory cytokine, during an early ischemic period. Furthermore, macrophages within the infarcted tissue expressed Bax protein and subsequently showed fragmented nuclear DNA. Oligodendrocytes were detected in the infarcted area even after 24 hours following middle cerebral artery occlusion, but they subsequently developed fragmented DNA. A week after onset of ischemia, oligodendrocytes were found to be accumulated in the intact area bordered with the infarct together with reactive astrocytes. CONCLUSIONS: Our results suggest the importance of amoeboid microglia, macrophages, and their interleukin-1beta production in gradual expansion of cerebral infarction. Resident oligodendrocytes may be resistant to ischemic insults, and oligodendrocytes accumulated at the border of the infarction may participate in tissue repair after cerebral infarction.

Animals↗

Diagnostic usefulness of the post-exercise systolic blood pressure response for the detection of coronary artery disease in patients with diabetes mellitus.

Patients with diabetes mellitus (DM) often have a positive result on exercise testing despite a normal coronary arteriogram, which indicates that exercise-induced ST depression is not always an accurate indicator of the presence of coronary artery disease (CAD) in such patients. The present study evaluated the usefulness of the post-exercise systolic blood pressure (SBP) response for the detection of CAD in 47 consecutive patients with DM. Significant stenotic lesions were detected by angiography in 25 patients; 18 of these had true positive (TP) exercise testing results, and 7 had false negative (FN) results. No significant stenotic lesions were detected in the remaining 22 patients and of these 10 had true negative (TN) exercise testing results, and 12 had false positive (FP) results. The SBP ratio (SBP after 3 min of recovery divided by the SBP at peak exercise) was significantly higher in patients with coronary stenoses than in those without. Analysis of the relative cumulative frequency revealed that a SBP ratio greater than 0.87 was associated with significant stenoses. The sensitivity, specificity, and accuracy of ST change combined with a SBP ratio greater than 0.87 for detecting stenoses in patients with DM were 68%, 82%, and 74%, respectively. These results suggest that calculating the SBP ratio, in combination with monitoring for ST depression, improves the accuracy of treadmill exercise testing for the detection of CAD in patients with DM.

Adult↗

Deficiency of intercellular adhesion molecule 1 fails to mitigate selective neuronal death after transient global ischemia.

Recent studies have shown a crucial role of intercellular adhesion molecule 1 (ICAM-1) in expansion of infarction after focal cerebral ischemia. The purpose of the present study was to assess whether ICAM-1 is involved in selective neuronal vulnerability and reactive gliosis after transient forebrain ischemia. ICAM-1 knockout mice and wild-type mice were subjected to transient forebrain ischemia for 5, 10 or 15 min, and the hippocampus and caudoputamen were examined 7 days later with conventional histological and immunohistochemical methods. Bilateral common carotid artery occlusion with less than 10% of baseline cortical microperfusion for 10 or 15 min resulted in ischemic neuronal damage in the hippocampus and caudoputamen. The frequency and the severity of neuronal damage were similar in wild-type and knockout mice. Proliferation of reactive astrocytes in the hippocampus was also similar in both types of mice. Therefore, it is highly unlikely that ICAM-1 plays a key role in delayed neuronal death after transient global ischemia or in astroglial responses after ischemic neuronal injury.

Animals↗

Species differences in fodrin proteolysis in the ischemic brain.

There has been growing evidence that the breakdown of cytoskeletal proteins is an important biochemical change leading to ischemic neuronal death. In the present study, we investigated species differences in the susceptibility of fodrin to calpain activation induced by cerebral ischemia in gerbils, rats, and mice. In vivo fodrin proteolysis and degradation of microtubule-associated protein 2 after complete ischemia occurred more rapidly in the hippocampus and cerebral cortex of the gerbil brain than in the corresponding area of the rat and mouse brain. The N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 injected intraperitoneally before ischemia did not diminish fodrin degradation in the gerbil hippocampus. In vivo fodrin proteolysis was inhibited at 33 degrees C and enhanced at 41 degrees C compared with proteolysis at 37 degrees C during ischemia. However, in vitro fodrin proteolysis after addition of Ca2+ into the crude membrane fraction did not show any differences among three species. Although it is highly unlikely that the difference in the sensitivity of NMDA receptor or the sensitivity of calpain activation to calcium was the crucial determinant of susceptibility of fodrin degradation in the gerbil brain, the present study clearly demonstrated that fodrin in the gerbil brain was more susceptible to calpain activation induced by ischemia than that in the rat and mouse brains. Enhanced proteolysis may be one of the reasons neurons in the gerbil brain are highly vulnerable to ischemia.

Animals↗