Biomedical subjects

V H Perry

Publications and source records attributed to V H Perry.

At least 55 records · Page 3Linked to original sources

PubMed1999

Delayed symptom onset and increased life expectancy in Sandhoff disease mice treated with N-butyldeoxynojirimycin.

Sandhoff disease is a neurodegenerative disorder resulting from the autosomal recessive inheritance of mutations in the HEXB gene, which encodes the beta-subunit of beta-hexosaminidase. GM2 ganglioside fails to be degraded and accumulates within lysosomes in cells of the periphery and the central nervous system (CNS). There are currently no therapies for the glycosphingolipid lysosomal storage diseases that involve CNS pathology, including the GM2 gangliosidoses. One strategy for treating this and related diseases is substrate deprivation. This would utilize an inhibitor of glycosphingolipid biosynthesis to balance synthesis with the impaired rate of catabolism, thus preventing storage. One such inhibitor is N-butyldeoxynojirimycin, which currently is in clinical trials for the potential treatment of type 1 Gaucher disease, a related disease that involves glycosphingolipid storage in peripheral tissues, but not in the CNS. In this study, we have evaluated whether this drug also could be applied to the treatment of diseases with CNS storage and pathology. We therefore have treated a mouse model of Sandhoff disease with the inhibitor N-butyldeoxynojirimycin. The treated mice have delayed symptom onset, reduced storage in the brain and peripheral tissues, and increased life expectancy. Substrate deprivation therefore offers a potentially general therapy for this family of lysosomal storage diseases, including those with CNS disease.

1-Deoxynojirimycin↗

PubMed1999

Induction of hyperphosphorylated tau in living slices of rat hippocampal formation and subsequent detection using an ELISA.

Although hyperphosphorylated tau is an established feature of Alzheimer's Disease, its role in the disease process is poorly understood, partly because of lack of suitable animal models. We describe the use of living slices of rat hippocampal formation to study tau phosphorylation. Using the AT8 antibody in an ELISA, phosphorylated tau was detected in freshly frozen slices and it increased significantly in slices that were incubated in an electrophysiological recording chamber; the amount detected was greatest when the homogenisation buffer contained phosphatase and kinase inhibitors. The phosphorylated tau content of the slices increased significantly after exposure to the phosphatase 1 and 2A inhibitor okadaic acid (OA) - 1.5 microM. Electrophysiological recordings confirmed that slices were alive and that OA had no acute toxic effect. In control slices phosphorylated tau, detected immunohistochemically, was mainly in the somatodendritic compartment of neurones; in OA treated slices, there was an apparent decrease in somatodendritic AT8 staining and an increase in neuropil staining. Our system enables the induction of hyperphosphorylated tau within living slices, in an experimental environment that can be used to study the biological consequences of such a change, and may therefore help further our understanding of the significance of hyperphosphorylated tau in Alzheimer's Disease.

Alzheimer Disease↗

PubMed1999

The major brain isoform of kif1b lacks the putative mitochondria-binding domain.

Kinesin and kinesin superfamily proteins are molecular motors involved in important intracellular functions such as organelle transport and cell division. They are microtubule-activated ATPases composed of a motor domain that binds to microtubules and a cargo-binding domain that binds to specific organelles. While searching for the slow Wallerian degeneration mutation (WldS) on distal mouse Chromosome (Chr) 4, we have identified a member of the kinesin superfamily whose predicted gene product has the N-terminal motor domain of Kif1b and a novel C-terminal cargo-binding domain homologous to Kif1a. Kif1b is responsible for the movement of mitochondria along the axon, but the novel isoform containing the alternative C-terminal domain is likely to have a different cargo-binding specificity. cDNA library screening and Northern blot analysis indicate that the alternatively spliced form of Kif1b containing the novel 3'end accounts for the most part of Kif1b expression. We also found more alternatively spliced exons that can give rise to heterogeneous transcripts. Therefore, alternative splicing, as well as multiple genes, may contribute to the selective movement of diverse organelles by anterograde axonal transport. Kif1b maps on distal mouse Chr 4, within the Wld genetic candidate interval, but outside the recently identified triplication. There is, however, no evidence that Kif1b is the Wld gene.

Alternative Splicing↗

PubMed1999

Heparin injection into the adult rat hippocampus induces seizures in the absence of macroscopic abnormalities.

The pathological hallmarks of Alzheimer's disease include neurofibrillary tangles, neuropil threads and neuritic plaques. Neurofibrillary tangles and neuropil threads are comprised of paired helical filaments which are themselves composed of a hyperphosphorylated form of the microtubule-associated protein tau. Neuritic plaques are extracellular deposits of aggregated beta amyloid associated with neurites containing hyperphosphorylated tau. The mechanisms by which the neurofibrillary tangles and neuritic plaques develop in Alzhemier's disease are not clear but it is hypothesized that sulphated glycosaminoglycans are important in their formation. This impression is based on the finding that the glycosaminoglycan, heparan sulphate, is found associated with neurofibrillary tangles, neuritic plaques and neuropil threads while dermatan sulphate, chondroitin sulphate and keratan sulphate immunoreactivity is found around neuritic plaques in brains of Alzheimer's disease patients. Furthermore, in vitro studies demonstrate that sulphated glycosaminoglycans such as heparan sulphate and the closely related molecule heparin interact with tau and potentiate its phosphorylation by a number of serine/threonine kinases, reduce its ability to bind to microtubules and induce paired helical filament formation, all properties associated with tau isolated from Alzheimer's disease brain. Thus, we were interested to learn whether intracerebral injection of the sulphated glycosaminoglycan heparin would give rise to alterations in the cytoskeletal protein tau in the rat brain. Although no cytoskeletal changes were observed, to our considerable surprise we found that the intrahippocampal injection of heparin gave rise to seizures. We have investigated this unexpected effect further in vivo and by using in vitro electrophysiological techniques.

Animals↗

PubMed1999

Restricted cyclooxygenase-2 expression in the central nervous system following acute and delayed-type hypersensitivity responses to bacillus Calmette-Guérin.

The expression of cyclooxygenase-2, a key enzyme in prostaglandin and thromboxane synthesis in inflammation, was studied immunohistochemically in in vivo models of acute and chronic inflammatory responses in rat central nervous system. In the acute inflammatory response to intracranial injection of heat-killed bacillus Calmette-Guérin as well as in the immune-mediated, delayed-type hypersensitivity response to the same pathogen, cyclooxygenase-2 expression was restricted to major infiltrating haematogenous cell populations such as neutrophils and mononuclear phagocytes, while the expression of the enzyme by brain non-neuronal resident cells (astrocytes, microglia, perivascular cells) appeared to be limited to perivascular cells of the blood vessels in the vicinity of the lesion and in the surrounding area. On the basis of their morphology and location, these perivascular cells were identified as perivascular macrophages, but we could not rule out the possibility that some endothelial cells also expressed cyclooxygenase-2. The constitutive neuronal cyclooxygenase-2 was not affected by the ongoing inflammation. Interestingly, in spite of the extensive astrocyte and microglial reaction occurring over a broad area surrounding the inflammatory lesions, there was no obvious cyclooxygenase-2 staining in these cells. These data indicate that the up-regulation of cyclooxygenase-2 expression in acute and chronic, immune-mediated lesions in the brain parenchyma is remarkably restricted to the lesion site. Since cyclooxygenase metabolites can regulate important functions of resident as well as infiltrating cells, the increased synthesis of prostaglandins and thromboxanes, which is likely to occur as a consequence of the expression of cycloxygenase-2 at the lesion site, might represent an important component of the inflammatory processes within the brain.

Animals↗

PubMed1999

Variation in the immune response to adenoviral vectors in the brain: influence of mouse strain, environmental conditions and priming.

E1-deleted adenoviral vectors expressing the bacterial beta-galactosidase gene were inoculated into the brain of unprimed and primed C3H.He or C57BL/6J mice housed under either conventional or specific-pathogen-free (SPF) conditions. The kinetics of immune responses to both the vector and the transgene were investigated. In mice previously sensitized to adenovirus, the leukocyte infiltrate in the brain was dominated by CD8+ T cells, whereas in unprimed mice CD4+ T cells were present at higher levels. As expected, antibody titres to both adenovirus and beta-galactosidase were higher in primed mice than in unprimed mice after intracranial inoculation. C3H.He mice consistently made higher antibody responses than C57BL/6J mice. Although adenoviral vectors induced an inflammatory response under all conditions, mice housed in SPF facilities exhibited less inflammation than conventional mice and transgene expression persisted for longer. Irrespective of whether the mice had been deliberately primed to adenovirus, antibody titres were consistently lower in SPF mice compared with conventional mice. This study clearly demonstrates that environmental conditions, as well as previous priming to adenovirus, will affect both the quality and duration of the immune response triggered by gene delivery to the brain.

Adenoviridae↗

PubMed1999

The acute inflammatory response in CNS following injection of prion brain homogenate or normal brain homogenate.

The neuropathological hallmarks of end-stage prion disease are vacuolation, neuronal loss, astrocytosis and deposition of PrPSc amyloid. We have also shown that there is an inflammatory response in the brains of scrapie-affected mice from 8 weeks post-injection. In this study we have investigated the acute CNS response to the intracerebral injection of scrapie-affected brain homogenate. The ME7 strain of scrapie (Neuropathogenesis Unit, Edinburgh) was used, and control mice were injected with brain homogenate derived from normal C57BL/6 J mice. One microlitre of 10% w/v ME7 (n = 33) and normal brain homogenate (n = 28) was injected stereotaxically into the right dorsal hippocampus. Cryostat sections of brains taken at 1, 2, 5, 7, 14 and 28 days post-injection were examined histologically for neuronal loss, and immunocytochemically to study the inflammatory response. This study shows that ME7 is not acutely neurotoxic in vivo. There is also no difference (ANOVA) in the inflammatory response, which peaked between 2 and 5 days and resolved by 4 weeks after intracerebral injection of either ME7 or normal brain homogenate. The well circumscribed inflammatory response seen previously at 8 weeks is therefore a consequence of a disease process rather than a surgical artefact. This disease process may be related to a localized accumulation of PrPSc sufficient to stimulate an inflammatory response which in turn may contribute to neuronal loss. The role of the inflammatory response in chronic neurodegeneration can be usefully studied using this mouse model of prion disease, and this will undoubtedly shed light on the pathogenic mechanisms underlying other chronic neurodegenerative diseases.

Acute Disease↗

PubMed1999

Non-nuclear histone H1 is upregulated in neurones and astrocytes in prion and Alzheimer's diseases but not in acute neurodegeneration.

A non-nuclear isoform of histone H1 is constitutively expressed in neurones. This protein is the major lipopolysaccharide (LPS)-binding protein in the brain. Since the major systemic LPS-binding protein is released in the liver and is an acute phase reactant, we were interested to learn whether this novel CNS histone showed altered expression following neuronal injury. We have therefore examined the changes in the expression of this molecule in acute neuronal injury and in two neurodegenerative pathologies, murine scrapie and Alzheimer's disease. No upregulation or change in H1 staining was observed in acute neurodegeneration induced by the intrastriatal injection of the glutamate antagonist N-methyl d-aspartic acid. In contrast, Western blotting indicated that histone H1 is upregulated in the brains of mice with clinical signs of scrapie. Immunohistochemistry revealed that in the regions of pathology there was increased staining for histone H1 in the neurones and the surrounding neuropil. Cells with an astrocytic appearance were also seen to stain positively for H1 but only in the regions of pathology. Immunofluorescent double staining for glial fibrillary acid protein (GFAP) and histone H1 confirmed that these cells were indeed astrocytes. Alzheimer's disease brain also showed an increase in the neuronal and astrocytic staining but only in regions of pathology. The function of histone in the CNS is unknown but the data presented here demonstrate an upregulation in areas of neuronal degeneration, which indicates that it may be involved in disease pathogenesis.

Acute Disease↗

PubMed1999

Inflammatory response and retinal ganglion cell degeneration following intraocular injection of ME7.

Scrapie is a prion disease which occurs naturally in sheep and which can be transmitted experimentally to rodents. After intracerebral injection of ME7 into mouse, an atypical inflammatory response, characterized by T-lymphocytes and activated microglia is present early in the course of the disease. In the present work, we have investigated the relationship between this inflammatory response, astrocytosis and neuronal loss along the visual pathway after intraocular injection (intraocular) of ME7 in C57BL/6J mice. We have demonstrated that microglia activation and T-lymphocyte recruitment accompanies the spread of prion pathology along the visual pathway and in the early stages of the disease is restricted to the subcortical visual pathway. Inflammation was also present in non-visual areas in association with PrPsc deposition at late stages of the disease, possibily indicating that diffusion of the scrapie agent also contributes to the spread of the disease. After intraocular injection of the prion agent, the disease is believed to be transported into the brain via axons of retinal ganglion cells (RGCs). Despite the high levels of infectivity reported to be present in the retina early in the disease after intraocular injection of ME7, retinal pathology has not been extensively investigated. We have studied the RGCs response in whole mount retinas after intraocular injection of ME7. We have shown that RGCs degenerate after intraocular injection of ME7 whereas amacrine cells, retinal interneurones, are more resistant. Our results suggest that two distinct population of neurones, exposed in vivo at the same time to the same agent scrapie strain, show different susceptibility to the toxic effects of PrPsc.

Animals↗

PubMed1999

Acute inflammatory responses to mechanical lesions in the CNS: differences between brain and spinal cord.

Lesion-induced inflammatory responses in both brain and spinal cord have recently become a topic of active investigation. Using C57BL/6J mice, we compared the tissue reaction in these two central nervous system (CNS) compartments with mechanical lesions of similar size involving both grey and white matter. This evaluation included the quantitative assessment of neutrophils, lymphocytes and activated macrophages/microglia, as well as astrocyte activation, upregulation of vascular cell adhesion molecules (ICAM-1, VCAM-1, PECAM) and the extent of blood-brain barrier (BBB) breakdown. Time points analysed post-lesioning included 1, 2, 4 and 7 days (as well as 10 and 14 days for the BBB). We found clear evidence that the acute inflammatory response to traumatic injury is significantly greater in the spinal cord than in the cerebral cortex. The numbers of both neutrophils and macrophages recruited to the lesion site were significantly higher in the spinal cord than in the brain, and the recruitment of these cells into the surrounding parenchyma was also more widespread in the cord. The area of BBB breakdown was substantially larger in the spinal cord and vascular damage persisted for a longer period. In the brain, as in spinal cord, the area to which neutrophils were recruited correlated well with the area of BBB breakdown. It will be of interest to determine the extent to which the infiltration of inflammatory cells contributes, either directly or indirectly, to the vascular permeability and secondary tissue damage or, conversely, to local tissue repair in the brain and the spinal cord.

Acute-Phase Reaction↗

PubMed1999

Cytokine-induced acute inflammation in the brain and spinal cord.

Different compartments in the central nervous system mount distinct inflammatory responses. The meninges and choroid plexus respond to pro-inflammatory stimuli in a manner reminiscent of a peripheral inflammatory response, whereas the brain parenchyma is refractory. Trauma-induced lesions in brain and in spinal cord are associated with leukocyte infiltration, blood-brain barrier (BBB) breakdown, and secondary tissue destruction. Unexpectedly, these phenomena are generally more pronounced in the parenchyma of the spinal cord than in the parenchyma of the brain. To investigate whether these differences between brain and spinal cord can be attributed, at least in part, to differing sensitivities to proinflammatory cytokines, we stereotactically injected recombinant rat (rr) TNFalpha or rrIL-1beta into the striatum or the spinal cord of Wistar rats. In the brain, the injection of rrTNFalpha failed to evoke BBB breakdown or leukocyte recruitment, whereas in the spinal cord injection of TNFalpha resulted in marked BBB breakdown and leukocyte recruitment. Similarly, the injection of rrIL-1beta into the brain parenchyma failed to induce BBB breakdown and gave rise to only minimal neutrophil recruitment, whereas the injection of rrIL-1beta into the spinal cord induced significant BBB breakdown and recruitment of neutrophils and lymphocytes. Thus, using a minimally invasive injection technique, equivalent in both circumstances, we have shown that there are marked differences in the inflammatory response between the brain parenchyma and spinal cord parenchyma. This observation has important implications for the treatment of spinal cord injuries.

Acute Disease↗

PubMed1999

In vivo expression of cyclooxygenase-2 in rat brain following intraparenchymal injection of bacterial endotoxin and inflammatory cytokines.

To clarify the role played by prostaglandins in acute brain inflammation we studied the expression of the key enzyme in their formation, cyclooxygenase-2 (COX-2), following microinjection of bacterial endotoxin (LPS), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma), in the rat dorsal hippocampus. In spite of the extensive astrocyte and microglial reaction, at 24 hours after LPS injection COX-2 immunoreactivity (COX-2-ir) was exclusively associated with infiltrating neutrophils and with perivascular cells of blood vessels in the area surrounding the injection site. Microinjection of IFN-gamma did not alter COX-2-ir, whereas TNF-alpha or IL-1beta injection induced a moderate COX-2-ir in the perivascular cells of a few blood vessels close to the injection site, and in very few of the infiltrating neutrophils. When IL-1beta, but not TNF-alpha or INF-gamma, was injected in combination with LPS, a strong COX-2-ir was associated with the perivascular cells of most blood vessels in the injected hemisphere and of several of those in the uninjected hemisphere. In addition, COX-2-ir was detected in neutrophils and in several parenchymal cells surrounding the injection site. The parenchymal and perivascular COX-2-positive cells showed a microglia/macrophage-like morphology, as compared with the GSI-B4 isolectin and ED-1 staining, specific for macrophages. Since the constitutive neuronal COX-2 was not affected by any of the conditions studied, the macrophage-like cells found in the perivascular region and in the parenchyma may represent the main source of prostaglandins during focal inflammatory responses in the brain.

Animals↗

PubMed1999

The therapeutic potential of CXC chemokine blockade in acute inflammation in the brain.

Mammalian neurones of the central nervous system (CNS) are terminally differentiated, and there is little endogenous capacity of the CNS to repair itself. Peripheral tissue injury, disease or infection results in a stereotypical inflammatory response to protect the host from pathogens and to promote tissue repair. However, collateral or 'bystander' damage is characteristic of any inflammatory response. Thus, it is apparent that the CNS has evolved mechanisms to regulate tightly the acute inflammatory response, and in particular to restrict the recruitment of neutrophils, in an attempt to protect itself from the potentially damaging consequences of inflammation in the brain. However, neutrophils are not always excluded from the brain. Indeed, they are found in large numbers in the brain parenchyma following traumatic lesions, stroke lesions, and in rodents, during the 'window of susceptibility'. Therapy targeted at blocking excitotoxic cell death has not successfully transferred from rodent models of stroke to human stroke patients. Restricting leukocyte entry to the brain, thereby inhibiting the inflammatory response, may prove to be a more practical therapeutic approach. The evidence presented in this review suggests that antagonising the effects of CXC chemokines may represent one route to achieve this goal.

Journal Article↗

PubMed1998

A revised view of the central nervous system microenvironment and major histocompatibility complex class II antigen presentation.

There are numerous observations reporting that phagocytes expressing major histocompatibility complex (MHC) Class II molecules are associated with the central nervous system (CNS) in normal and pathological conditions. Although MHC Class II expression is necessary for antigen presentation to CD4 + T-cells, it is not sufficient and co-stimulatory molecules are also required. We review here recent in vivo studies demonstrating that the microglia and perivascular macrophages are unable to initiate a primary immune response in the CNS microenvironment, but may support secondary immune responses. Although in vitro studies show that microglia do not support a primary immune response leading to T-cell proliferation, they do show that microglia may protect the CNS from the unwanted attentions of autoreactive T-cells by inducing their apoptosis. The lack of cells in the CNS parenchyma with the ability to initiate a primary immune response has a cost, namely that pathogens may persist in the CNS undetected by the immune system.

Animals↗

PubMed1998

An 85-kb tandem triplication in the slow Wallerian degeneration (Wlds) mouse.

Wallerian degeneration is the degeneration of the distal stump of an injured axon. It normally occurs over a time course of around 24 hr but it is delayed in the slow Wallerian degeneration mutant mouse (C57BL/Wlds) for up to 3 weeks. The gene, which protects from rapid Wallerian degeneration, Wld, previously has been mapped to distal chromosome 4. This paper reports the fine genetic mapping of the Wld locus, the generation of a 1.4-Mb bacterial artificial chromosome and P1 artificial chromosome contig, and the identification of an 85-kb tandem triplication mapping within the candidate region. The mutation is unique to C57BL/Wlds among 36 strains tested and therefore is a strong candidate for the mutation that leads to delayed Wallerian degeneration. There are very few reports of tandem triplications in a vertebrate and no evidence for a mutation mechanism so this unusual mutation was characterized in more detail. Sequence analysis of the boundaries of the repeat unit revealed a minisatellite array at the distal boundary and a matching 8-bp sequence at the proximal boundary. This finding suggests that recombination between short homologous sequences ("illegitimate" or "nonhomologous" recombination) was involved in the rearrangement. In addition, a duplication allele was identified in two Wlds mice, indicating some instability in the repeat copy number and suggesting that the triplication arose from a duplication by unequal crossing over.

Alleles↗

PubMed1998

Matrix metalloproteinase expression in an experimentally-induced DTH model of multiple sclerosis in the rat CNS.

In an experimentally-induced DTH model of MS, we examined mRNA and protein expression of a range of MMPs and of TNFalpha to establish the contribution that individual MMPs might make to the pathogenesis. In control rat brain, mRNA for all of the MMPs examined was detectable. However, by immunohistochemistry, only MMP-2 could be detected. In the DTH lesions, significant increases in the level of mRNA expression were observed for MMP-7, MMP-8, MMP-12, and TNFalpha. Where expression of MMP mRNA was increased, there was a corresponding increase in protein expression detected by immunohistochemistry. To determine whether the upregulated MMPs could invoke destructive events in the CNS, highly purified activated MMP-7, MMP-8, and MMP-9 were stereotaxically injected into the brain parenchyma. All provoked recruitment of leukocytes and BBB breakdown. In addition, MMPs 7 and 9 induced loss of myelin staining. In conclusion, specific MMPs are upregulated in DTH lesions; for the most part, measurement of mRNA was a predictor of increased protein expression. From our injections of MMPs, it is clear that the upregulated MMPs in the DTH lesions could participate in the disruption of the BBB, leukocyte recruitment, and tissue damage.

Animals↗

PubMed1998

Mannan-binding lectin in human serum, cerebrospinal fluid and brain tissue and its role in Alzheimer's disease.

Mannan-Binding lectin (MBL) is a serum lectin which can activate the classical complement pathway. Complement proteins of the classical pathway have been found in the brains of patients with Alzheimer's disease (AD) in association with AD brain pathology. To investigate the role for MBL in AD we have looked for its presence in the brain by immunohistochemistry and determined the levels of MBL in paired samples of cerebrospinal fluid and serum from AD patients and controls. MBL was detected in association with blood vessels in the brain tissue of both AD patients and control subjects. There was no apparent difference in the distribution of MBL in the brain tissue between the two groups. The mean concentration of MBL in the CSF was 44% lower in AD patients than in controls (AD 154 +/- 35 pg/ml, n = 19; non-AD 276 +/- 50 pg/ml, n = 15, p < 0.05). The levels of MBL in serum were not significantly different in the two groups. Thus, this study shows that MBL is associated with blood vessels in the brains of both AD and control subjects. Moreover, CSF levels of MBL appear to be lower in AD patients than in control subjects which may indicate a higher degree of MBL consumption connected with complement activation in the AD patients.

Aged↗

PubMed1998

Stroke: a double-edged sword for cleaving clots?

The discovery that tissue plasminogen activator can promote neuronal degeneration has uncovered a novel pathway leading to neuronal cell death and raises important issues concerning the use of tissue plasminogen activator as a thrombolytic therapy for stroke.

Animals↗