Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Accumulating evidence strongly suggests that apoptosis contributes to neuronal cell death in a variety of neurodegenerative contexts. Activation of the cysteine protease caspase-3 appears to be a key event in the execution of apoptosis in the central nervous system (CNS). As a result, mice null for caspase-3 display considerable neuronal expansion usually resulting in death by the second week of life. At present, 14 caspase family members have been identified and subdivided into three subgroups on the basis of preference for specific tetrapeptide motifs using a positional scanning combinatorial substrate library. Caspase-3 is a group II member (2, 3, 7) categorized by an absolute substrate requirement for aspartic acid in the P4 position of the scissile bond. The preferred cleavage motif (DExD) for group II caspases is found in many structural, metabolic and repair proteins essential for cellular homeostasis. Consistent with the proposal that apoptosis plays a central in role human neurodegenerative disease, caspase-3 activation has recently been observed in stroke, spinal cord trauma, head injury and Alzheimer's disease. Indeed, peptide-based caspase inhibitors prevent neuronal loss in animal models of head injury and stroke suggesting that these compounds may be the forerunners of non-peptide small molecules that halt apoptosis processes implicated in these neurodegenerative disorders. A clear link between an hereditary neurodegenerative disorder and failed caspase inhibition has recently been proposed for spinal muscular atrophy (SMA). In severe SMA, the neuronal specific inhibitor of apoptosis (IAP) family member known as NAIP is often dysfunctional due to missense and truncation mutations. IAPs such as NAIP potently block the enzymatic activity of group II caspases (3 and 7) suggesting that NAIP mutations may permit unopposed developmental apoptosis to occur in sensory and motor systems resulting in lethal muscular atrophy. Conversely, adenovirally-mediated overexpression of NAIP or the X-linked IAP called XIAP reduces the loss of CA1 hippocampal neurons following transient forebrain ischemia. Taken together, these findings suggest that anti-apoptotic strategies may some day have utility in the treatment of neurodegenerative disease. The present review will summarize some of the recent evidence suggesting that apoptosis inhibitors may become a practical therapeutic approach for both acute and chronic neurodegenerative conditions.
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PMID:Neuroprotection by the inhibition of apoptosis. 1076 48

The brain's response to ischemia, which helps determine clinical outcome after stroke, is regulated partly by competing genetic programs that respectively promote cell survival and delayed cell death. Many genes involved in this response have been identified individually or systematically, providing insights into the molecular basis of ischemic injury and potential targets for therapy. The development of microarray systems for gene expression profiling permits screening of large numbers of genes for possible involvement in biological or pathological processes. Therefore, we used an oligodeoxynucleotide-based microarray consisting of 374 human genes, most implicated previously in apoptosis or related events, to detect alterations in gene expression in the hippocampus of rats subjected to 15 minutes of global cerebral ischemia followed by up to 72 hours of reperfusion. We found 1.7-fold or greater increases in the expression of 57 genes and 1.7-fold or greater decreases in the expression of 34 genes at 4, 24, or 72 hours after ischemia. The number of induced genes increased from 4 to 72 hours, whereas the number of repressed genes decreased. The induced genes included genes involved in protein synthesis, genes mutated in hereditary human diseases, proapoptotic genes, antiapoptotic genes, injury-response genes, receptors, ion channels, and enzymes. We detected transcriptional induction of several genes implicated previously in cerebral ischemia, including ALG2, APP, CASP3, CLU, ERCC3, GADD34, GADD153, IGFBP2, TIAR, VEGF, and VIM, as well as other genes not so implicated. We also found coinduction of several groups of related genes that might represent functional modules within the ischemic neuronal transcriptome, including VEGF and its receptor, NRP1; the IGF1 receptor and the IGF1-binding protein IGFBP2; Rb, the Rb-binding protein E2F1, and the E2F-related transcription factor, TFDP1; the CACNB3 and CACNB4 beta-subunits of the voltage-gated calcium channel; and caspase-3 and its substrates, ACINUS, FEM1, and GSN. To test the hypothesis that genes identified through this approach might have roles in the pathophysiology of cerebral ischemia, we measured expression of the products of two induced genes not heretofore implicated in cerebral ischemia-GRB2, an adapter protein involved in growth-factor signaling pathways, and SMN1, which participates in RNA processing and is deleted in most cases of spinal muscular atrophy. Western analysis showed enhanced expression of both proteins in hippocampus at 24 to 72 hours after ischemia, and SMN1 was localized by immunohistochemistry to hippocampal neurons. These results suggest that microarray analysis of gene expression may be useful for elucidating novel molecular mediators of cell death and survival in the ischemic brain.
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PMID:Microarray analysis of hippocampal gene expression in global cerebral ischemia. 1145 15

Penile erection is a vascular phenomenon that results from smooth muscle relaxation, arterial dilation and venous restriction. The atherosclerosis of the penis that occurs with aging causes a decrease in penile oxygen tension. A reduction of smooth muscle cells has been demonstrated in relation with this change in oxygen tension. Changes in the ratio of penile collagen have also been observed and could explain the decrease in penile elasticity and compliance. Chronic ischemia is, therefore, associated with fibrosis but also with nitric oxide (NO)-cyclic guanosine monophosphate. The sensitivity of the alpha-adrenoceptors on the smooth muscle cells increases with aging. All those modifications can explain the prevalence of erectile dysfunction with aging. Low oxygen tension in prostanoid production may also play a role in the mechanism of ischemia-induced cavernosal fibrosis; however, intracavernous injections of prostaglandin E(1) do not seem to modify the intracavernous structures by reducing muscular atrophy. The effects of androgen on libido and sexual behavior are well established, but their role in the human erectile mechanism remains unclear. Several studies performed on animals have demonstrated impacts directly on both the physiological function and the trabecular structure of the corpora cavernosa in rats, dogs and rabbits. However, in humans, no study seems to demonstrate a role of testosterone on muscular atrophy or penile neurologic control. Testosterone treatment alters the human behavior but not penile physiologic processes. Further studies are necessary to explain the real role of testosterone not only on the peripheral mechanism of erection but also on the central control.
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PMID:Smooth muscle pathology and erectile dysfunction. 1185 Jul 30

After atraumatic birth, three neonates presented with muscle hypotonia and weakness. Flaccid paresis of the upper extremities, spasticity of the lower extremities, dissociate sensory loss and autonomic dysfunction developed later. This ruled out the initial, tentative diagnoses of cerebral palsy, spinal muscular atrophy or hereditary neuropathy. Diagnostic imaging revealed marked thinning of the cervical spinal cord in all patients. The possible aetiology of these lesions is considered. In all cases, an antenatal or perinatal infarction is thought to be the most probable cause. Different clinical pictures following intrauterine spinal cord ischemia are discussed. Spinal cord lesion must be considered even after atraumatic birth.
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PMID:Cervical spinal cord atrophy in the atraumatically born neonate: one form of prenatal or perinatal ischaemic insult? 1269 May 68

Although spaceflight and bed rest are known to cause muscular atrophy in the antigravity muscles of the legs, the changes in sympathetic and cardiovascular responses to exercises using the atrophied muscles remain unknown. We hypothesized that bed rest would augment sympathetic responses to isometric exercise using antigravity leg muscles in humans. Ten healthy male volunteers were subjected to 14-day 6 degrees head-down bed rest. Before and after bed rest, they performed isometric exercises using leg (plantar flexion) and forearm (handgrip) muscles, followed by 2-min postexercise muscle ischemia (PEMI) that continues to stimulate the muscle metaboreflex. These exercises were sustained to fatigue. We measured muscle sympathetic nerve activity (MSNA) in the contralateral resting leg by microneurography. In both pre- and post-bed-rest exercise tests, exercise intensities were set at 30 and 70% of the maximum voluntary force measured before bed rest. Bed rest attenuated the increase in MSNA in response to fatiguing plantar flexion by approximately 70% at both exercise intensities (both P < 0.05 vs. before bed rest) and reduced the maximal voluntary force of plantar flexion by 15%. In contrast, bed rest did not alter the increase in MSNA response to fatiguing handgrip and had no effects on the maximal voluntary force of handgrip. Although PEMI sustained MSNA activation before bed rest in all trials, bed rest entirely eliminated the PEMI-induced increase in MSNA in leg exercises but partially attenuated it in forearm exercises. These results do not support our hypothesis but indicate that bed rest causes a reduction in isometric exercise-induced sympathetic activation in (probably atrophied) antigravity leg muscles.
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PMID:Bed rest attenuates sympathetic and pressor responses to isometric exercise in antigravity leg muscles in humans. 1470 16

Programmed cell death or apoptosis is a physiologically important process in neurogenesis wherein approximately 50% of the neurons apoptose during maturation of the nervous system. However, premature apoptosis and/or aberrations in apoptosis control contribute to the pathogenesis of a variety of neurological disorders including acute brain injury such as trauma, spinal cord injury, ischemic stroke and ischemia/reperfusion as well as chronic disease states such as Alzheimer's, Parkinson's, Huntington's, amyotrophic lateral sclerosis, spinal muscular atrophy, and diabetic neuropathy. The current review will focus on two major topics, namely, the general concepts of our current understanding of the apoptosis death machinery, its mediators and regulation, and the relationship between aberrant apoptosis and genesis of neurodegenerative disorders. This knowledge of apoptosis mechanisms will underpin the basis for development of novel therapeutic strategies and treatment modalities that are directed at control of the neuronal apoptotic death program.
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PMID:Apoptosis in acute and chronic neurological disorders. 1497 68

The purpose of this study was to characterize microneurovascular (MNV) muscle transplants immunohistochemically up to 10 years after transfer. Histological data was related to long-term functional outcome. The study comprised 17 patients with a mean age of 41 years suffering from complete unilateral long-lasting facial paralysis. A two-stage procedure was performed between 1986 and 2001. The gracilis, latissimus dorsi, and serratus muscles were used in four, eight, and five patients, respectively. Eighteen biopsy samples were taken from MNV muscle grafts during secondary refinement procedures. In one patient, the tissue samples were collected at two different time points. Immunohistochemistry testing revealed muscle fiber type distribution (anti-myosin fast), proliferating satellite cells (Ki-67), and reinnervation (S-100). Muscle atrophy was assessed histomorphometrically. In a recent study, patient characteristics and the function of the flap were evaluated. Histological data were compared with clinical data and long-term functional outcomes of the patients. In biopsy samples taken 1-10 (mean 31 months) years after MNV muscle transfer, the mean muscle fiber diameter was 38 (range 14-70) microm, indicating a 40% decrease compared with control values. Muscle atrophy was not type-specific and the mean percentage of type II fibers was not altered. Individual variation was, however, considerable. Proliferative activity of satellite cells was seen in 60% of the samples but it tended to decline with an increase in follow-up time. All samples showed intramuscular reinnervation. In statistical analysis severe atrophy correlated with prolonged intraoperative ischemia (P=0.04). The good long-term functional outcome correlated with dominance of fast fibers in muscle grafts (P=0.03). Atrophy tended to be more pronounced in the serratus than in the other muscles (ns). In summary, despite dense muscle reinnervation, morphology of the muscle is not fully restored after muscle transfer. Ischemia time affects muscle morphology. Adaptation of the graft to fast-twitch muscle activity favors better mimic function. The proliferative activity of satellite cells declines with prolonged follow-up time.
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PMID:Long-term adaptation of human microneurovascular muscle flaps to the paralyzed face: an immunohistochemical study. 1706 8

This disease occurs in adolescence, predominatly in male. The main clinical features include predominantly unilateral muscular weakness and wasting of the hand and forearm (the brachioradialis is spared: oblique amyotrophy). The clinical course is incidious onset and slowly progressive, followed by a spontaneous arrest within several years. Twelve patients with this disease were first reported by Hirayama and his associates in 1959, who clinically distinguished this disorder from previously known degenerative and progressive motor neuron diseases. The clinical features had been further clarified by the report on 20 patients in 1963, and completed in the report on 38 patients in 1972. A quarter of a century had passed without pathological confirmation, primarily due to the benign course of the disease. The first autopsy case was obtained in 1982. The neuropathological findings were reported by Hirayama and his associates in 1985 in Japanese, then in 1987 in English. The spinal cord showed anteroposterior flattening and ischemic necrotic changes of the anterior horns of the cervical cord at C5-T1, mostly severe at C7 and C8, predominantly on the left (the patient had bilateral muscular atrophy, predominantly on the left). These findings suggested a circulatory insufficiency of the lower cerivical cord, but the intra- and extra-medullary vessels were normal. The pathologic evidence prompted neuroradiologic (CT, MRI) studies in the late 1980s. Our studies of 73 patients revealed that dynamic compression of the lower cervical cord due to forward displacement of the cervical dural sac (especially posterior segment) and spinal cord on neck flexion was confined to an early and progressive stage of the disease. An absence of forward displacement in a later and non-progressive stage of the disease suggested that the dynamic compression had pathogenic significance. The pathologic findings and results of radiological studies suggest that sustained or repeated neck flexion might cause an anterior shift of the cervical dural sac, then the compressed cervical cord at the segments induce an increased intramedullary pressure, resulting in microcirculatory disturbance in the anterior horn, the most vulnerable structure to ischemia in the spinal cord. Based on this hypothesis, we tried cervical collar therapy for patients when they may have sustained or repeated neck flexion, and reported these data in 1991, 1992 and 2001. No one showed further progression of signs and symptoms. This favorable effect supports our pathogenic hypothesis described above. The author proposes that the etiology of this disease is disproportionate growth between the vertebral column and the contents of the spinal canal especially the dural sac during the juvenile growth. The nationwide epidemiological study in Japan was carried out from 1996 to 1998, identified 333 cases of the disease. There were fewer case reports from other countries than from Japan. As the number of patients is exceedingly large in Japan, there might be an ethnic factor in this disorder.
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PMID:[Juvenile muscular atrophy of unilateral upper extremity (Hirayama disease)--half-century progress and establishment since its discovery]. 1823 29

We studied two 16-year-old males with juvenile muscular atrophy of the distal arm, "Hirayama disease," resulting in asymmetric atrophy and weakness of the distal upper extremities. Pathogenic theories include a compressive myelopathy with or without ischemia, and occasional cases are accounted for by genetic mutations. To specifically address the ischemia hypothesis we performed spinal angiography and epidural venography. Neck flexion during spinal angiography showed a forward shift of a nonoccluded anterior spinal artery without impedance to blood flow. Epidural venography demonstrated engorgement of the posterior epidural venous plexus without obstruction to venous flow. The findings do not support large vessel obstruction as a contributory factor. The Hirayama hypothesis continues to best explain the disease pathogenesis: neck flexion causes tightening of the dura and intramedullary microcirculatory compromise with resultant nerve cell damage. The age-related factor can most likely be accounted for by a growth imbalance between the vertebral column and the cord/dural elements. Resolution of progression is associated with cessation of body growth, after which the symptoms plateau or modestly improve. Muscle Nerve 40: 206-212, 2009.
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PMID:Spinal angiography and epidural venography in juvenile muscular atrophy of the distal arm "Hirayama disease". 1960 8

We report a case of acute-onset dropped head syndrome in a 65-year-old patient in whom the diagnosis of amyotrophic lateral sclerosis (ALS) was initially proposed based on electromyographic signs of neck and shoulder muscle denervation. There were no signs of pyramidal involvement and the clinical and electromyographic signs of motor denervation never evolved beyond the neck and shoulder girdle muscles after a 6-year follow-up period, which argued against ALS. Other causes of dropped head syndrome were carefully ruled out based on clinical findings, electrodiagnostic studies and blood investigations. The restriction of muscle denervation to a few cervical myotomes, the presence of C3-C4 spondylotic changes without associated root or spinal cord compression, and the absence of an alternative explanation to the patient's symptoms strongly supported the diagnosis of cervical spondylotic amyotrophy (CSA). CSA is thought to result from spinal cord microcirculatory disturbances and secondary anterior horn cell degeneration due to ischemia. Our case enlarges the clinical spectrum of focal cervical anterior horn disease, which classically results in more distal monomelic atrophy affecting one or both upper limbs.
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PMID:Cervical spondylotic amyotrophy presenting as dropped head syndrome. 1964 27


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