Studies from several laboratories have generated evidence suggesting that oxidative stress is involved in the pathogenesis of Alzheimer's disease (AD). The finding that the amyloid ␤ protein (A␤) has neurotoxic properties and that such effects are, in part, mediated by free radicals has provided insights into mechanisms of cell death in AD and an avenue to explore new therapeutic approaches. In this study we demonstrate that melatonin, a pineal hormone with recently established antioxidant properties, is remarkably effective in preventing death of cultured neuroblastoma cells as well as oxidative damage and intracellular Ca 2ϩ increases induced by a cytotoxic fragment of A␤. The effects of melatonin were extremely reproducible and corroborated by multiple quantitative methods, including cell viability studies by confocal laser microscopy, electron microscopy, and measurements of intracellular calcium levels. The importance of this finding is that, in contrast to conventional antioxidants, melatonin has a proposed physiological role in the aging process. Secretion levels of this hormone are decreased in aging and more severely reduced in AD. The reported phenomenon may be of therapeutic relevance in AD.

Widespread cerebral deposition of a 40 -43-amino acid peptide called the amyloid ␤-protein (A␤) in the form of amyloid fibrils is one of the most prominent neuropathologic features of Alzheimer's disease. Numerous studies suggest that A␤ is toxic to neurons by free radical-mediated mechanisms. We have previously reported that melatonin prevents oxidative stress and death of neurons exposed to A␤. In the process of screening indole compounds for neuroprotection against A␤, potent neuroprotective properties were uncovered for an endogenous related species, indole-3-propionic acid (IPA). This compound has previously been identified in the plasma and cerebrospinal fluid of humans, but its functions are not known. IPA completely protected primary neurons and neuroblastoma cells against oxidative damage and death caused by exposure to A␤, by inhibition of superoxide dismutase, or by treatment with hydrogen peroxide. In kinetic competition experiments using free radical-trapping agents, the capacity of IPA to scavenge hydroxyl radicals exceeded that of melatonin, an indoleamine considered to be the most potent naturally occurring scavenger of free radicals. In contrast with other antioxidants, IPA was not converted to reactive intermediates with pro-oxidant activity. These findings may have therapeutic applications in a broad range of clinical situations.Brains of patients afflicted with Alzheimer's disease show abnormal expression of numerous oxidative stress indicators (1-5) as well as extensive evidence of oxidative damage to proteins (6) and nucleic acids (7,8). A prominent feature of the Alzheimer's disease brain is the widespread cerebral deposition of a 40 -43-amino acid peptide called the amyloid ␤-protein (A␤) 1 in the form of amyloid fibrils within senile plaques and in cerebral and meningeal blood vessels (9, 10). A large body of data suggests that A␤ causes neuronal degeneration and death by mechanisms that involve reactive oxygen species reviewed in Ref. 15).Since the severity of the dementia in Alzheimer's disease has been correlated best with the extent of synaptic loss and the degree of neuronal death (16, 17), enhancing neuronal survival has been a primary objective of many therapeutic strategies. We have recently reported that melatonin prevents oxidative stress and death of neurons exposed to the amyloid peptide (18,19). In the process of screening indole compounds as neuroprotective agents, new properties were uncovered for an endogenous species, indole-3-propionic acid (IPA). IPA has previously been identified in the plasma and cerebrospinal fluid of humans, but its functions are not known (20,21). IPA has, like melatonin, a heterocyclic aromatic ring structure with high resonance stability, which led us to suspect similar neuroprotective and antioxidant properties. Here, we report that IPA prevented oxidative stress and death of primary neurons and neuroblastoma cells exposed to A␤. In addition, IPA also showed a strong level of neuroprotection in two other paradigms of oxidative stress. We found...

Extramedullary plasmacytomas are solitary tumors consisting of neoplastic plasma cell proliferations that occur in locations other than bone. On initial presentation they must be differentiated from multiple myeloma. This may prove to be difficult because a varying percentage may be associated at a later date with the development of multiple myeloma. Solitary extramedullary plasmacytomas represent up to 4% of nonepithelial lesions of the upper respiratory tract. From 1970 to 1990, at West Virginia University Hospitals, seven patients with solitary extramedullary plasmacytoma were identified. In four of these patients the tumor was located in the head and neck, with one tumor located in each of the following sites: temporoparietal scalp, maxillary sinus, nasopharynx, and cervical region. One patient had extensive destruction of the temporal bone, with extension intracranially to the middle cranial fossa. No patient had multiple myeloma, nor did any develop. Diagnosis was based on a combination of histology along with special immunoperoxidase staining for Ig lambda and kappa light chains. This will be demonstrated and discussed. Treatment consisted of radiotherapy in three cases, with doses ranging from 3175 to 6000 rad. One patient, treated with surgical excision, experienced a relapse at a distant site 6 years later. All patients have maintained local control and have been followed for a minimum of 1 1/2 years, with an average of 3 years. We describe our experience with these tumors and present a pertinent review of the literature. While these tumors may present as aggressive locally destructive lesions, their management should be as organ-sparing as possible because excellent control can be achieved in the majority of cases.(ABSTRACT TRUNCATED AT 250 WORDS)

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SUMMARY Liver ischaemia was induced by cross clamping the hilar pedicle for 30 minutes in groups of rats with or without treatment with the iron chelating agent desferrioxamine (deferoxamine, DFR). The groups included eight animals each and were divided into the following treatment categories: control; ischaemia alone; ischaemia with subsequent reperfusion; ischaemia preceded by DFR, 60 mg/kg body weight; and reperfusion preceded by 20, 40, or 60 mg/kg DFR. The drug was given intravenously five minutes before either ischaemia or reperfusion. Malondialdehyde (MDA), a product of lipid peroxidation, and histopathological changes of liver tissue samples were used as indicators of hepatocellular injury. Lipid peroxidation (MDA concentration in [imolkg liver tissue) was highest (4.76 (1P19)) after ischaemia without reperfusion and less pronounced (2-87 (0.34)) after reperfusion. Both concentrations, however, were significantly (p<005) higher than basal (control) values (1P78 (0.27)). At 60 mg/kg body weight, DFR treatment reduced MDA to basal or even lower concentrations in both situations (1.98 (0.08) and 1.26 (0.06), respectively) with a corresponding improvement in liver histopathology. Lower DFR doses were less protective. The data suggest that liver ischaemia is associated with free radical initiated, and apparently iron catalysed lipid peroxidation, which can be significantly decreased by iron chelation.The harmful effects of complete interruption of blood flow to an organ has long been a topic of intense interest. Complete interruption of blood flow to the liver is often necessary during surgical intervention for trauma or when extensive resection of a tumour is performed.' With the recent development of liver transplantation, the effects of temporary ischaemia on restoration of liver function are of even greater importance. Under these conditions, the harmful consequences of liver ischaemia and subsequent reflow on liver function are often related to injury at the cellular and subcellular level (membrane integrity, mitochondrial function, protein synthesis, DNA, etc).-4Damage to cell and organelle membranes is probably the critical lesion that precedes irreversible cell injury.' This has been largely attributed to peroxida-

We studied heat shock protein (HSP) synthesis by cultured human neuroblastoma cells in response to either hyperthermia or high levels of superoxide anion (oxygen free radical). Both treatment modalities resulted in induced synthesis of the same major HSP species with an additive effect on the latter and on cell growth inhibition upon combined treatments. Exposure to superoxide anion in the presence of the free radical scavenging enzymes, superoxide dismutase and catalase improved cell survival and prevented HSP induction. These findings suggest a common mechanism by which various forms of injury, such as hyperthermia, cause HSP induction, that is, via oxidative stress or increased production of oxygen free radicals. Increased expression of some HSPs has been detected in association with the pathological lesions that characterize some neurodegenerative diseases such as the neurofibrillary tangles of Alzheimer's disease. This, in turn, suggests that chronic oxidative stress may play a role in the pathogenesis of these disorders.

A large body of data suggests that the Alzheimer's amyloid peptide (Ab) causes degeneration and death of neurons by mechanisms that involve reactive oxygen species. The pathways involved in Ab-mediated oxidative injury are only partially understood. We theorized that abnormal microaggregates and/or pathological conformations of Ab peptides may behave as xenobiotics and trigger the induction of NADPH cytochrome P450 reductase (CP450r), an enzyme which, if induced by non-physiological substrates (such as xenobiotics like drugs or other`foreign molecules'), is known to cause oxidative stress. In order to test this hypothesis, i.e. that Ab can increase the expression of CP450r, SK-N-SH human neuroblastoma cells were exposed to Ab25-35 and Ab1-42 and then examined for induction of this enzyme in immunoblots, using speci®c antibodies. Following exposure to Ab peptides, neuroblastoma cells showed a clear-cut induction of CP450r. To determine whether this mechanism is operational in vivo, we investigated the expression of CP450r in a transgenic mouse model of Alzheimer's disease (AD) and in brains from patients af¯icted with AD, using an immunocytochemical approach. Tissue sections from brains of transgenic mice exhibited strong immunoreactivity for CP450r, surrounding amyloid deposits. The pattern of expression of CP450r was similar to that exhibited by neuritic and oxidative stress markers. Sections from non-transgenic mice showed no detectable immunoreactivity. Immunostaining of sections from four brains with neuropathologically con®rmed AD showed a pattern of abnormality different from transgenic mice that was characterized by abnormal immunoreactivity for CP450r within the cytoplasm of cortical neurons. No labeling was seen in sections from aged-matched control brains. The data showed that CP450r is induced by Alzheimer amyloid peptide and that such a response must be considered as one possible mechanism whereby Ab causes oxidative stress.

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