Search PubMed⌕ Search

Biomedical subjects

G Perry

Publications and source records attributed to G Perry.

At least 127 records · Page 7Linked to original sources
PubMed1998

A randomized trial of granulocyte colony-stimulating factor (Neupogen) starting day 1 vs day 7 post-autologous stem cell transplantation.

The purpose of the study was to evaluate the effect of delayed granulocyte colony-stimulating factor (G-CSF) use on hematopoietic recovery post-autologous peripheral blood progenitor cell (PBPC) transplantation. Patients were randomized to begin G-CSF on day +1 or day +7 post transplantation. Thirty-seven patients with lymphoma or myeloma undergoing high-dose therapy and autologous PBPC rescue were randomized to daily subcutaneous G-CSF beginning on day +1 or day +7 post-transplant. Patients < or =70 kg received 300 microg/day and >70 kg 480 microg/day. All patients were reinfused with PBPCs with a CD34+ cell count >2.0 x 10(6)/kg. Baseline characteristics of age, sex and CD34+ cell count were similar between the two arms, the median CD34+ cell count being 5.87 x 10(6)/kg in the day +1 group and 7.70 x 10(6)/kg in the day +7 group (P=0.7). The median time to reach a neutrophil count of >0.5 x 10(9)/l was 9 days in the day +1 arm and 10 days in the day +7 arm, a difference which was not statistically significant (P=0.68). Similarly, there was no difference in median days to platelet recovery >20000 x 10(9)/l, which was 10 days in the day +1 arm and 11 days in the day +7 arm (P=0.83). There was also no significant difference in the median duration of febrile neutropenia (4 vs 6 days; P=0.7), intravenous antibiotic use (7 vs 8 days; P=0.54) or median number of red blood cell transfusions (4 vs 7 units; P=0.82) between the two arms. Median length of hospital stay was 11 days post-PBPC reinfusion in both groups. The median number of G-CSF injections used was 8 in the day +1 group and 3 in the day +7 group (P < 0.0001). There is no significant difference in time to neutrophil or platelet recovery when G-CSF is initiated on day +7 compared to day +1 post-autologous PBPC transplantation. There is also no difference in number of febrile neutropenic or antibiotic days, number of red blood cell transfusions or length of hospital stay. The number of doses of G-CSF used per transplant is significantly reduced with delayed initiation, resulting in a significant reduction in drug costs. For patients with an adequately mobilized PBPC graft, the initiation of G-CSF can be delayed until day +7 post-PBPC reinfusion.

Adult↗
PubMed1998

Amyloid-beta deposition in Alzheimer transgenic mice is associated with oxidative stress.

Increased awareness for a role of oxidative stress in the pathogenesis of Alzheimer's disease has highlighted the issue of whether oxidative damage is a fundamental step in the pathogenesis or instead results from disease-associated pathology. In vitro experiments support both possibilities: Oxidative stress increases amyloid-beta production, and, conversely, amyloid-beta increases oxidative damage. To address the relationship between amyloid-beta and oxidative stress in vivo, we examined, using an array of oxidative markers, transgenic mice that overexpress amyloid-beta precursor protein and, as in Alzheimer's disease, develop characteristic amyloid-beta deposits within the brain parenchyma. Transgenic animals show the same type of oxidative damage that is found in Alzheimer's disease, and it is important that this damage directly correlates with the presence of amyloid-beta deposits. The significance of these studies is twofold. First, they provide evidence that amyloid-beta and oxidative damage are inextricably linked in vivo. Second, they support the use of transgenic animals for the development of antioxidant therapeutic strategies.

Aldehydes↗
PubMed1998

Altered glycosylation pattern of proteins in Alzheimer disease.

Post-translational modifications due to glycosylation of proteins in human brains from patients with Alzheimer disease (AD) were analyzed using lectin histochemistry. Results indicate a significant increase in the production of O-glycosylated (containing Galbeta1,3GalNAc alpha1,0 Ser/Thr or GalNAc alpha1,0 Ser/Thr) proteins in neuritic plaques and neurofibrillary tangles which are the major histopathological hallmarks of AD brains. These alterations were determined by positive labelling with lectins obtained from Amaranthus leucocarpus (ALL) and Macrobrachium rosenbergii (MRL) respectively. Immunohistochemistry indicated that the lectin-staining labelled specifically both neurofibrillary tangles and neuritic plaques. In contrast, lectins labelling was restricted to microvessels in normal control brains. These results provide evidence that modifications of the specific glycosylation patterns are closely related with the presence of the hallmark lesions of this disease, suggesting that an abnormal enzymatic processing of proteins may be an early event in the neuronal degeneration which characterises AD.

Aged↗
PubMed1998

Cytochemical demonstration of oxidative damage in Alzheimer disease by immunochemical enhancement of the carbonyl reaction with 2,4-dinitrophenylhydrazine.

Formation of carbonyls derived from lipids, proteins, carbohydrates, and nucleic acids is common during oxidative stress. For example, metal-catalyzed, "site-specific" oxidation of several amino acid side-chains produces aldehydes or ketones, and peroxidation of lipids generates reactive aldehydes such as malondialdehyde and hydroxynonenal. Here, using in situ 2,4-dinitrophenylhydrazine labeling linked to an antibody system, we describe a highly sensitive and specific cytochemical technique to specifically localize biomacromolecule-bound carbonyl reactivity. When this technique was applied to tissues from cases of Alzheimer disease, in which oxidative events including lipoperoxidative, glycoxidative, and other oxidative protein modifications have been reported, we detected free carbonyls not only in the disease-related intraneuronal lesions but also in other neurons. In marked contrast, free carbonyls were not found in neurons or glia in age-matched control cases. Importantly, this assay was highly specific for detecting disease-related oxidative damage because the site of oxidative damage can be assessed in the midst of concurrent age-related increases in free carbonyls in vascular basement membrane that would contaminate biochemical samples subjected to bulk analysis. These findings demonstrate that oxidative imbalance and stress are key elements in the pathogenesis of Alzheimer disease.

Adult↗
PubMed1998

Evidence of oxidative stress and in vivo neurotoxicity of beta-amyloid in a transgenic mouse model of Alzheimer's disease: a chronic oxidative paradigm for testing antioxidant therapies in vivo.

Increased expression of antioxidant enzymes and heat-shock proteins are key markers of oxidative stress. Such proteins are abnormally present within the neuropathological lesions of Alzheimer's disease (AD), suggesting that oxidative stress may play significant but yet undefined roles in this disorder. To gain further insight into the role of oxidative stress in AD, we studied the expression of CuZn superoxide dismutase (SOD) and hemoxygenase-1 (HO-1), two established markers of oxidative stress, in a transgenic mouse model of AD. Immunohistochemistry with anti-SOD and anti-HO-1 antibodies revealed a very pronounced increase of these proteins only in aged transgene-positive mice. Interestingly, the distribution of the oxidative burden was largely overlapping with dystrophic neuritic elements in the mice as highlighted with anti-ubiquitin antibodies. Because the most conspicuous alterations were identified around amyloid (Abeta) deposits, our results provide strong support for the hypothesis that Abeta is neurotoxic in vivo and that such toxicity is mediated by free radicals. To obtain additional experimental evidence for such an interpretation (ie, a cause-effect relationship between Abeta and oxidative neurotoxicity), PC12 cells were exposed to increasing concentrations of Abeta or to oxidative stress. In agreement with the in vivo findings, either treatment caused marked induction of SOD or HO-1 in a dose-dependent fashion. These results validate the transgenic approach for the study of oxidative stress in AD and for the evaluation of antioxidant therapies in vivo.

Aging↗
PubMed1997

Iron accumulation in Alzheimer disease is a source of redox-generated free radicals.

Damage from free radicals has been demonstrated in susceptible neuronal populations in cases of Alzheimer disease. In this study, we investigated whether iron, a potent source of the highly reactive hydroxyl radical that is generated by the Fenton reaction with H2O2, might contribute to the source of radicals in Alzheimer disease. We found, using a modified histochemical technique that relies on the formation of mixed valence iron complexes, that redox-active iron is associated with the senile plaques and neurofibrillary tangles-the pathological hallmark lesions of this disease. This lesion-associated iron is able to participate in in situ oxidation and readily catalyzes an H2O2-dependent oxidation. Furthermore, removal of iron was completely effected using deferoxamine, after which iron could be rebound to the lesions. Characterization of the iron-binding site suggests that binding is dependent on available histidine residues and on protein conformation. Taken together, these findings indicate that iron accumulation could be an important contributor toward the oxidative damage of Alzheimer disease.

Adult↗
PubMed1997

Advanced glycation modification of Rosenthal fibers in patients with Alexander disease.

Rosenthal fibers, astrocytic inclusions that accumulate in various neoplastic and non-neoplastic conditions, are a characteristic of Alexander disease, a leukodystrophy of unknown etiology. Given that alphaB crystallin is the major protein component of Rosenthal fibers and that crystallins in the diabetic and aged lens are targets for advanced glycation end product modifications via the Maillard reaction we hypothesized that Rosenthal fibers might contain similar modifications. Using antibodies specific for two products of glycation, pyrraline and pentosidine, we showed labeling of Rosenthal fibers that may account for their insolubility and accumulation. These data suggest that advanced glycation end products may be critical to the pathogenesis of Alexander disease.

Adolescent↗
PubMed1997

Widespread peroxynitrite-mediated damage in Alzheimer's disease.

Increasing evidence suggests that oxidative damage to proteins and other macromolecules is a salient feature of the pathology of Alzheimer's disease. Establishing the source of oxidants is key to understanding what role they play in the pathogenesis of Alzheimer's disease, and one way to examine this issue is to determine which oxidants are involved in damage. In this study, we examine whether peroxynitrite, a powerful oxidant produced from the reaction of superoxide with nitric oxide, is involved in Alzheimer's disease. Peroxynitrite is a source of hydroxyl radical-like reactivity, and it directly oxidizes proteins and other macromolecules with resultant carbonyl formation from side-chain and peptide-bond cleavage. Although carbonyl formation is a major oxidative modification induced by peroxynitrite, nitration of tyrosine residues is an indicator of peroxynitrite involvement. In brain tissue from cases of Alzheimer's disease, we found increased protein nitration in neurons, including but certainly not restricted to those containing neurofibrillary tangles (NFTs). Conversely, nitrotyrosine was undetectable in the cerebral cortex of age-matched control brains. This distribution is essentially identical to that of free carbonyls. These findings provide strong evidence that peroxynitrite is involved in oxidative damage of Alzheimer's disease. Moreover, the widespread occurrence of nitrotyrosine in neurons suggests that oxidative damage is not restricted to long-lived polymers such as NFTs, but instead reflects a generalized oxidative stress that is important in disease pathogenesis.

Aged↗
PubMed1997

Is amyloid beta-protein glycated in Alzheimer's disease?

Recent data suggest that protein glycation is involved in the process of amyloid formation in Alzheimer's disease (AD). To further investigate this issue, we analyzed the presence of advanced glycation end products (AGE) in soluble and insoluble forms of amyloid beta-protein (A beta) as well as in apolipoprotein E (apoE), a protein bound to amyloid deposits. Both proteins were extracted from cerebral cortex obtained from patients with AD and probed by immunoblotting with two antibodies specific for different AGE, already known to immunocytochemically label amyloid plaques. All the AGE antibodies failed to recognize either A beta or apoE, whereas they reacted with synthetic A beta glycated in vitro. These findings indicate that other proteins associated with amyloid deposits are candidates to be modified with AGE in Alzheimer's cerebral tissue.

Alzheimer Disease↗
PubMed1997

Protocol for quantitative analysis of paired helical filament solubilization: a method applicable to insoluble amyloids and inclusion bodies.

Biochemical studies of amyloidoses have been plagued by the sparing solubility of most amyloids in denaturant solvents. Consequently often only a subclass of amyloid protein is analyzed, a fact that is omitted in most studies. This means that there is often no evaluation of the chemical basis for amyloid insolubility, a factor that may provide valuable information concerning amyloid pathogenesis. We have devised a protocol to quantitatively evaluate the solubilization of insoluble amyloid proteins. Specifically, we use protein extraction and reduction in the volume of insoluble material as quantitative assays to establish solvents that dissolve all protein. Here we describe the application of this protocol to quantitatively establish complete solubilization of the paired helical filaments (PHFs) from Alzheimer disease. PHFs are distinct from the other amyloid that defines Alzheimer disease (AD), i.e., extracellular amyloid-beta deposits of senile plaques, nonetheless, PHFs share all the properties of, and are defined as, an amyloid, i.e., binding Congo red; beta-pleated sheet conformation and, most significantly, sparing solubility. PHFs of neurofibrillary tangles are the most striking intraneuronal change seen within the brains of patients with AD. Despite intense efforts to understand the molecular composition of this amyloid, quantitative biochemical analyses have been severely hampered by the extreme insolubility of PHF and by difficulties obtaining a homogeneous PHF fraction. Therefore, to date, all of the published studies on the biochemical composition of insoluble PHFs (SDS-insoluble) are qualitative and have provided little or no quantitative data on the proportion of material assayed. Using the solubilization protocol described herein, we found that only high pH was effective in solubilizing PHF while a variety of denaturants and chaotropes resulted in only partial release of component protein. Significantly, the approach is analytical because it allows direct assessment of the significance of two posttranslational modifications in mediating PHF insolubility, i.e., phosphorylation and glycation. Further this protocol provides solubilized protein that can be readily characterized. For example, coupling the method to immunoblotting, ELISA, microsequencing or other analytical techniques would identify components as well as provide a quantitative measure.

Alzheimer Disease↗
PubMed1997

Levuglandin E2-protein adducts in human plasma and vasculature.

The prostaglandin endoperoxide PGH2 rearranges nonenzymatically to generate prostaglandins and secoprostanoic acid levulinaldehyde derivatives such as PGE2 and levuglandin (LG) E2, respectively. Direct detection of LGE2 in biological samples is complicated because it is rapidly sequestered by covalent adduction to endogenous nucleophiles including proteins, which produces LGE2-derived protein-bound pyrroles. Therefore, to detect LGE2-protein adducts in vivo, antibodies were raised against a covalent adduct of LGE2 with keyhole limpet hemocyanin (KLH). This antigen enabled the production of high-titer antibodies that exhibit minimal cross-specificity and are sensitive for detecting LGE2-derived pyrroles. Although pyrrole yields are low at LG/protein ratios found in vivo, an enzyme-linked immunosorbent assay with the LGE2-KLH antibodies detects LGE2-derived protein-bound pyrrole immunoreactivity in human plasma from specific patient populations. Furthermore, prominent immunocytochemical staining of human brain thin sections revealed the presence of LGE2-derived pyrrole immunoreactivity, especially in the meningeal vessels of some patients. This demonstration of LG-protein adducts in human plasma and vasculature provides the first evidence for the biological occurrence of levuglandins in vivo and further suggests that these antibodies might prove useful in diagnostic and mechanistic studies of various disease conditions.

Adolescent↗
PubMed1997

Altered expression of fibrogenic growth factors in IgA nephropathy and focal and segmental glomerulosclerosis.

The profile of fibrogenic growth factor expression was assessed in biopsies from 27 patients with IgA nephropathy (IgAN), 14 focal and segmental glomerulsclerosis (FSGS) patients and 8 controls, by immunohistochemistry. Increased platelet-derived growth factor (PDGF)-A and PDGF-B expression was detected in glomeruli and in vascular structures and collapsed tubules in the interstitium. Computer assisted image analysis demonstrated increased glomerular PDGF-A in IgAN (P < 0.05), but not FSGS patients, compared to controls, suggesting an association with mesangial proliferation. PDGF receptors were prominent in areas of mesangial expansion and intertubular fibrosis. Significant increases in interstitial PDGF Receptor beta (PDGFR-beta) were detected for both IgAN (P < 0.01) and FSGS (P < 0.05) patients. Interstitial PDGFR-beta expression was significantly correlated to monocyte/macrophage infiltrate (P < 0.0001). Increased basic fibroblast growth factor (bFGF) expression was observed segmentally in glomeruli, and in areas of tubulointerstitial damage. Higher proportions of patients with FSGS than IgAN had elevated interstitial bFGF (P < 0.005) and PDGF, reflecting the more severe degree of vascular and tubulointerstitial injury in FSGS patients. This study demonstrates distinct patterns of fibrinogenic growth factors in IgAN and FSGS, strongly associated with the severity and type of injury.

Adult↗
PubMed1997

4-Hydroxynonenal-derived advanced lipid peroxidation end products are increased in Alzheimer's disease.

Recent studies have demonstrated oxidative damage is one of the salient features of Alzheimer's disease (AD). In these studies, glycoxidation adduction to and direct oxidation of amino acid side chains have been demonstrated in the lesions and neurons of AD. To address whether lipid damage may also play an important pathogenic role, we raised rabbit antisera specific for the lysine-derived pyrrole adducts formed by lipid peroxidation-derived 4-hydroxynonenal (HNE). These antibodies were used in immunocytochemical evaluation of brain tissue from AD and age-matched control patients. HNE-pyrrole immunoreactivity not only was identified in about half of all neurofibrillary tangles, but was also evident in neurons lacking neurofibrillary tangles in the AD cases. In contrast, few senile plaques were labeled, and then only the dystrophic neurites were weakly stained, whereas the amyloid-beta deposits were unlabeled. Age-matched controls showed only background HNE-pyrrole immunoreactivity in hippocampal or cortical neurons. In addition to providing further evidence that oxidative stress-related protein modification is a pervasive factor in AD, the known neurotoxicity of HNE suggests that lipid peroxidation may also play a role in the neuronal death in AD that underlies cognitive deficits.

Aged↗