A novel factor isolated from Actinobacillus actinomycetemcomitans stimulates mouse B cells and human peripheral blood mononuclear cells

A novel immunostimulating factor (ISTF) of Actinobacillus actinomycetemcomitans ATCC 29522 was isolated and characterized as inducing proliferation of mouse B cells and human peripheral blood mononuclear cells. This factor was isolated from the bacterial culture medium and purified by size exclusion chromatography, dye-ligand affinity chromatography, immunoaffinity chromatography using monoclonal antibodies, and preparative electrophoresis. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the purified ISTF migrated as a single band corresponding to a molecular mass of 13 kDa. ISTF was a proteinaceous material distinct from lipopolysaccharide; it directly induced the proliferation of B lymphocytes but had no effect on the proliferation of T lymphocytes, even in the presence of antigen-presenting cells. A B-lymphocyte-mitogenic activity of ISTF was also shown by flow cytometric analysis of responding cell subpopulations. Immunoblot analysis revealed that ISTF was a component of the outer membranes of bacteria, could exist as a soluble form, and was released by growing and/or lysed bacteria. These results suggest that ISTF produced by A. actinomycetemcomitans may play an important role in immunopathologic changes associated with A. actinomycetemcomitans infections.

Carboxyl-terminal fragment of Alzheimer's APP destabilizes calcium homeostasis and renders neuronal cells vulnerable to excitotoxicity

Numerous lines of evidence indicate that some of the neurotoxicity associated with Alzheimer's disease (AD) is due to proteolytic fragments of the amyloid precursor protein (APP). Most research has focused on the amyloid beta peptide (Abeta). However, the possible role of other cleaved products of APP is less clear. We have previously shown that a recombinant carboxy-terminal 105 amino acid fragment (CT 105) of APP induced strong nonselective inward currents in Xenopus oocyte; it also revealed neurotoxicity in PC12 cells and primary cortical neurons, blocked later phase of long-term potentiation in rat hippocampus in vivo, and induced memory deficits and neuropathological changes in mice. We report here that the pretreatment with CT 105 for 24 h at a 10 microM concentration increases intracellular calcium concentration by about twofold in SK-N-SH and PC 12 cells, but not in U251 cells, originated from human glioblastoma. In addition, the calcium increase and toxicity induced by CT 105 were reduced by cholesterol and MK 801 in SK-N-SH and PC 12 cells, whereas the toxicity of Abeta(1-42) was attenuated by nifedipine and verapamil. CT 105 rendered SK-N-SH cells and rat primary cortical neurons more vulnerable to glutamate-induced excitotoxicity. Also, conformational studies using circular dichroism experiments showed that CT 105 has approximately 15% of beta-sheet content in phosphate buffer and aqueous 2,2, 2-trifluoroethanol solutions. However, the content of beta-sheet conformation in dodecyl phosphocholine micelle or in the negatively charged vesicles, is increased to 22%-23%. The results of this study showed that CT 105 disrupts calcium homeostasis and renders neuronal cells more vulnerable to glutamate-induced excitotoxicity, and that some portion of CT 105 has partial beta-sheet conformation in various environments, which may be related to the self-aggregation and toxicity. This may be significantly possibly involved in inducing the neurotoxicity characteristic of AD.

Sedative activity of two flavonol glycosides isolated from the flowers of Albizzia julibrissin Durazz

The flowers of Albizzia julibrissin are used as a sedative in oriental traditional medicine. The phytochemical study of this plant allowed the isolation of two flavonol glycosides, quercitrin (1) and isoquercitrin (2). The sedative activity of these compounds was evaluated, and both compounds 1 and 2 increased pentobarbital-induced sleeping time in dose-dependent manner in mice. These results support the use of the flowers of this plant as a sedative agent.

Activated platelets induce secretion of interleukin-1beta, monocyte chemotactic protein-1, and macrophage inflammatory protein-1alpha and surface expression of intercellular adhesion molecule-1 on cultured endothelial cells

Atherosclerosis is an inflammatory disease. Platelet-endothelium interaction plays an important role in the pathophysiology of atherogenesis. We investigated the role of activated platelets for secretion of interleukin (IL)-1beta, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-1alpha and expression of intercellular adhesion molecule (ICAM)-1 on endothelial cells. Human umbilical vein endothelial cells (HUVEC) were incubated with non-stimulated or ADP-activated platelets for 6 hr. Secretion of interleukin (IL)-1beta, MCP-1 and MIP-1alpha and surface expression of ICAM-1 were measured by ELISA and flow cytometry. In the presence of activated platelets, the secretion of IL-1beta, MCP-1, and MIP-1alpha and surface expression of ICAM-1 were significantly increased compared with non-activated platelets. The present study shows that activated platelets may contribute to expression of various inflammatory mediators on endothelial cells.

Glutamate and aspartate impair memory retention and damage hypothalamic neurons in adult mice

We examined the effects of systemic administration of monosodium glutamate (MSG) or aspartate (ASP) on the memory retention and neuronal damage in the brains of adult mice. Compared with the control mice, a single intraperitoneal injection of either 4.0 mg/g MSG or 0.5 mg/g ASP after acquisition trial significantly shortened the response latency in the passive avoidance test, accompanying by the transient weight loss. Histopathological analysis of the brains of these mice revealed that neurons in the arcuate nucleus of hypothalamus were damaged markedly by MSG (4.0 mg/g) or ASP (0.5 mg/g). Other brain areas including cerebral cortex and hippocampus did not show any pathological changes. These findings suggest that systemic administration of MSG or ASP could impair memory retention and damage hypothalamic neurons in adult mice.

APP carboxyl-terminal fragment without or with abeta domain equally induces cytotoxicity in differentiated PC12 cells and cortical neurons

Mutations in the beta-amyloid precursor protein (APP) gene cause familial Alzheimer's disease (AD). Although amyloid beta peptide (Abeta) is the principal constituent of senile plaques in AD, other cleavage products of APP are also implicated in playing a role in the pathogenesis of AD. C-terminal fragments of APP (APP-CTs), that contain complete Abeta sequence, are found in neuritic plaques, neurofibrillary tangles and the cytosol of lymphoblastoid cells obtained from AD patients. Our previous report demonstrated that APP-CT105 causes death of differentiated PC12 cells and cultured rat cortical neurons (Kim and Suh [1996] J. Neurochem. 67:1172-1182) and induces strong inward currents in Xenopus oocyte (Fraser et al., [1996] J. Neurochem. 66:2034-2040). In the present study, to investigate which domain of APP-CT105 is responsible for the neurotoxicity, we have made deletion mutants of APP-CT105 without Abeta and transmembrane domain (TM) or without NPTY domain, a putative endocytosis signaling sequence, using the PCR-amplified strategy and the recombinant GST-fusion protein strategy. The effect on cell survival of the deletion mutants of APP-CT105 (8 microM) was then determined by the LDH and MTT assay. We found that C-terminal fragment without NPTY significantly causes cell death in NGF-differentiated PC12 cells and cultured rat cortical neurons. This finding suggests that NPTY may not play an important role in APP-CT105 mediated neurotoxicity. We found, however, that C-terminal fragment without Abeta and TM significantly induces neuronal cell death. Our results suggest that in addition to Abeta, C-terminal fragment of APP without Abeta and TM domain itself may also participate in the neuronal degeneration in AD.

Rotundines A-C, three novel sesquiterpene alkaloids from Cyperus rotundus

Rotundines A (1), B (2), and C (3), three novel sesquiterpene alkaloids with an unprecedented carbon skeleton, were isolated from the rhizomes of Cyperus rotundus. The structures of 1-3 were elucidated by spectral and chemical methods.

Cytotoxic lavandulyl flavanones from Sophora flavescens

Two new lavandulylated flavanones, (2S)-2'-methoxykurarinone (1) and (-)-kurarinone (2), were isolated from the root of Sophora flavescens, together with two known lavandulyl flavanones, sophoraflavanone G (3) and leachianone A (4), and two known isoflavonoids, formononetin and l-maakiain. The structures of 1 and 2 were determined on the basis of optical rotation and spectral evidence and by comparison with known compounds. Compounds 1-4 exhibited cytotoxic activity against human myeloid leukemia HL-60 cells.

Hyaluronidase inhibitory active 6H-dibenzo[b,d]pyran-6-ones from the feces of Trogopterus xanthipes

Bioassay-guided fractionation of the MeOH extract of Pteropi faeces (the feces of Trogopterus xanthipes Milne-Edwards) furnished three hyaluronidase inhibitory active 6H-dibenzo[b,d]-pyran-6-ones (1-3), together with a new compound, 3,8,10-trihydroxy-6H-dibenzo[b,d]pyran-6-one (4). Their structures were established on the basis of the spectroscopic methods.

Roles of A beta and carboxyl terminal peptide fragments of amyloid precursor protein in Alzheimer disease

Several lines of evidence indicate that A beta may play an important role in the pathogenesis of AD. However, there are several discrepancies between the production of A beta and the development of the disease. Thus, A beta may not be the sole active fragment of beta-amyloid precursor protein (betaAPP) in the neurotoxicity assiciated with AD. We focused on the amyloidegenic carboxyl terminal fragments of betaAPP containing the full length of A beta (CT105). We synthesized a recombinant carboxyl-terminal 105 amino acid fragment of betaAPP and examined the effects of CT105 and A beta on cultured neurons, Ca++ uptake into rat brain microsomes, Na+-Ca++ exchange activity, ion channel forming activity in lipid bilayers and passive avoidance performance of mice. Our results suggest that the cytotoxic and channel inducing effects of CT105 are much more potent than that of A beta and toxic mechanisms of CT105 are different from those of A beta. Taken together, these lines of evidence postulate that CT is an alternative toxic element important in the generation of the symptoms common to AD.

Dehydroevodiamine.HCl prevents impairment of learning and memory and neuronal loss in rat models of cognitive disturbance

We previously reported that dehydroevodiamine.HCl (DHED) has anticholinesterase and antiamnesic activities. To verify the effects of DHED on cognitive deficits further, we tested it on the scopolamine-induced amnesia model of the rat using the passive avoidance and eight-arm radial maze tests. A single (20 mg/kg p.o.) and repeated (10 mg/kg p.o.) administrations of DHED could significantly reverse the latency time shortened by scopolamine (1 mg/kg i.p.) to control level. The impaired spatial working memory induced by scopolamine (1 mg/kg i.p.) was also improved significantly by a single injection (6.25 mg/kg i.p.) and repeated administrations of DHED (10 mg/kg p.o.) in the eight-arm radial maze test. In addition, we examined the effects of DHED on the memory impairment and the histological changes of the brain after unilateral electrolytic lesion of the entorhinal cortex (EC) and middle cerebral artery occlusion in rats. The cognitive deficits caused by EC lesion and middle cerebral artery occlusion were improved significantly by repeated administrations of DHED (6.25 mg/kg i.p.) after EC lesion or ischemic insult once a day for 7 days in the passive avoidance test. Histological analysis showed that the neuronal loss in the DHED-treated group was notably reduced in the hippocampal area (CA1) of ischemic rats and in the dentate gyrus and hippocampal area (CA1 and CA3) of EC-lesioned rats compared with the nontreated group. The infarction area was decreased significantly by a single administration of DHED (6.25 mg/kg i.p.) 30 min before ischemic insult for 6 h. These results suggest that DHED might be an effective drug for not only the Alzheimer's disease type, but also the vascular type of dementia.

Sensing of ionizing radiation-induced DNA damage by ATM through interaction with histone deacetylase

The ATM gene is mutated in individuals with ataxia telangiectasia, a human genetic disease characterized by extreme sensitivity to radiation. The ATM protein acts as a sensor of radiation-induced cellular damage and contributes to cell cycle regulation, signal transduction, and DNA repair; however, the mechanisms underlying these functions of ATM remain largely unknown. Binding and immunoprecipitation assays have now shown that ATM interacts with the histone deacetylase HDAC1 both in vitro and in vivo, and that the extent of this association is increased after exposure of MRC5CV1 human fibroblasts to ionizing radiation. Histone deacetylase activity was also detected in immunoprecipitates prepared from these cells with antibodies to ATM, and this activity was blocked by the histone deacetylase inhibitor trichostatin A. These results suggest a previously unanticipated role for ATM in the modification of chromatin components in response to ionizing radiation.

Scopoletin: an inducible nitric oxide synthesis inhibitory active constituent from Artemisia feddei

Bioassay-guided fractionation of an H2O extract of Artemisia feddei has furnished an inducible nitric oxide synthase (iNOS) inhibitory coumarin, scopoletin (1) and one of the inactive sesquiterpenes, achillin (2). Compound 1 showed inhibition of nitric oxide (NO) synthesis in a dose-dependent manner in murine macrophage-like RAW 264.7 cells stimulated with interferon-gamma (IFN-gamma) plus lipopolysaccharide (LPS). The inhibition of NO synthesis of 1 was due to suppression of iNOS mRNA and iNOS protein, as determined by Northern and Western blotting, respectively.

Norlignans with Hyaluronidase Inhibitory Activity from Anemarrhena asphodeloides

Assay-guided fractionation of an MeOH extract of ANEMARRHENA ASPHODELOIDES Bunge has furnished two hyaluronidase inhibitory norlignans, CIS-hinokiresinol ( 1) and 1,3-di- P-hydroxyphenyl-4-penten-1-one ( 2), and an inactive norlignan 4'-methyl- CIS-hinokiresinol ( 3). Compound 2 is a new compound.

Effects of interleukin-2 transduction on the human hepatoma cell lines using retroviral vector

Gene therapy, using cytokine gene transduction, aims to increase the antigenicity of tumor cells, and to activate the immune effector cells, and thereby inducing tumor regression. With regards to in vitro sensitivity to peripheral blood monocytes and in vivo tumorigenic activity we compared the differences between parent hepatoma cell lines and interleukin-2 (IL-2) transduced hepatoma cell lines using N2A/IL-2 and LNC/IL-2 retrovirus. IL-2 secretion was 186 pg/10(6) cells/24 h in SK-Hep1 cell line and 147 pg/106 cells/24 h in Hep-3B cell line with N2A/IL-2 retroviral vector and was 55,000 pg/10(6) cells/24 h in Hep-3B cell line with LNC/IL-2 retroviral vector. in vitro sensitivity to peripheral blood monocytes was increased by 163.8-254% in IL-2 transduced hepatoma cell lines (Hep-3B/LNC/IL-2, Hep-G2/LNC/IL-2) compared to those of the parent cell lines. The tumor was formed in 1 of 3 BALB/c mice and all 3 nude mice with the injection of 1x107 cells. Simultaneous injection of 1x10(7) cells of the parent cell line (Hep-3B) into the right flank and IL-2 transduced cell line (Hep-3B/LNC/IL-2) into the left flank of the three BALB/c mice and of 5x10(5) cells for the three nude mice resulted in a complete regression of the IL-2 modified tumor cell line (Hep-3B/LNC/IL-2) in 3 weeks and the parent cell line (Hep-3B) in 5 weeks. After injection of 1x10(7) cells into five other nude mice, the tumor of the IL-2 transduced hepatoma cells (Hep-3B/LNC/IL-2) gradually disappeared, however, the tumor of the parent hepatoma cell line initially decreased and then gradually regrew 20 days later. In conclusion, IL-2 transduced hepatoma cell lines secreting IL-2 became more sensitive to peripheral blood monocytes. IL-2 secretion by LNC/IL-2 retrovirus from the hepatoma cell lines was more prominent compared with that by N2A/IL-2 retrovirus. IL-2 transduction into the hepatoma cells resulted in increased antigenicity to the tumors formed by IL-2 transduced hepatoma cell line and parent cell line, which leads the regression of the tumors. However, the higher the tumor burden, the less efficient tumor regression by IL-2 transduction into the hepatoma cell line in nude mice was observed.

Effects of interleukin-2 transduction on the human hepatoma cell lines using retroviral vector

Gene therapy, using cytokine gene transduction, aims to increase the antigenicity of tumor cells, and to activate the immune effector cells, and thereby inducing tumor regression. With regards to in vitro sensitivity to peripheral blood monocytes and in vivo tumorigenic activity we compared the differences between parent hepatoma cell lines and interleukin-2 (IL-2) transduced hepatoma cell lines using N2A/IL-2 and LNC/IL-2 retrovirus. IL-2 secretion was 186 pg/10(6) cells/24 h in SK-Hep1 cell line and 147 pg/106 cells/24 h in Hep-3B cell line with N2A/IL-2 retroviral vector and was 55,000 pg/10(6) cells/24 h in Hep-3B cell line with LNC/IL-2 retroviral vector. in vitro sensitivity to peripheral blood monocytes was increased by 163.8-254% in IL-2 transduced hepatoma cell lines (Hep-3B/LNC/IL-2, Hep-G2/LNC/IL-2) compared to those of the parent cell lines. The tumor was formed in 1 of 3 BALB/c mice and all 3 nude mice with the injection of 1x107 cells. Simultaneous injection of 1x10(7) cells of the parent cell line (Hep-3B) into the right flank and IL-2 transduced cell line (Hep-3B/LNC/IL-2) into the left flank of the three BALB/c mice and of 5x10(5) cells for the three nude mice resulted in a complete regression of the IL-2 modified tumor cell line (Hep-3B/LNC/IL-2) in 3 weeks and the parent cell line (Hep-3B) in 5 weeks. After injection of 1x10(7) cells into five other nude mice, the tumor of the IL-2 transduced hepatoma cells (Hep-3B/LNC/IL-2) gradually disappeared, however, the tumor of the parent hepatoma cell line initially decreased and then gradually regrew 20 days later. In conclusion, IL-2 transduced hepatoma cell lines secreting IL-2 became more sensitive to peripheral blood monocytes. IL-2 secretion by LNC/IL-2 retrovirus from the hepatoma cell lines was more prominent compared with that by N2A/IL-2 retrovirus. IL-2 transduction into the hepatoma cells resulted in increased antigenicity to the tumors formed by IL-2 transduced hepatoma cell line and parent cell line, which leads the regression of the tumors. However, the higher the tumor burden, the less efficient tumor regression by IL-2 transduction into the hepatoma cell line in nude mice was observed.

Inhibition of nitric oxide synthesis by butanol fraction of the methanol extract of Ulmus davidiana in murine macrophages

Since there is increasing evidence that nitric oxide (NO) plays a crucial role in the pathogenesis of inflammatory diseases, this study was undertaken to address whether the methanol (MeOH) extract and its fractions of the bark of Ulmus davidiana Planch (Ulmaceae) could modulate the expression of inducible NO synthase (iNOS) in thioglycollate-elicited murine peritoneal macrophages and murine macrophage cell line, RAW264.7 cells. Stimulation of the peritoneal macrophages and RAW264.7 cells with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) resulted in increased production of NO in the medium. However, the butanol (BuOH) fraction of the MeOH extract of U. davidiana barks showed marked inhibition of NO synthesis in a dose-dependent manner. The inhibition of NO synthesis was reflected in the decreased amount of iNOS protein, as determined by Western blotting. The BuOH fraction did not affect the viability of RAW264.7 cells, as assessed by methylthiazol-2-yl-2, 5-diphenyl tetrazolium bromide (MTT) assay; rather, it reduced endogenous NO-induced apoptotic cell death via inhibition of NO synthesis in RAW264.7 cells. On the other hand, the BuOH fraction showed no inhibitory effect on the synthesis of NO by RAW264.7 cells, when iNOS was already expressed by the stimulation with IFN-gamma and LPS. Collectively, these results demonstrate that the BuOH fraction inhibits NO synthesis by inhibition of the induction of iNOS in murine macrophages.

Post-ischemic changes in the expression of Alzheimer's APP isoforms in rat cerebral cortex

A significant porportion (25%) of patients with Alzheimer's disease (AD) also shows vascular pathology. Recent ultrastructural studies demonstrated characteristic and extensive angio-architectural distortions of cerebral capillaries in AD brains. We examined the expression of APP mRNA isoforms of cerebral cortex after transient ischemia by middle cerebral artery occlusion, using RT-PCR. Neuronal damage and glial fibrillary acidic protein immunohistochemistry were also examined histologically. After transient ischemia, the Kunitz protease inhibitor-bearing isoforms (KPI-APP) were increased whereas APP 695, which lacks KPI domain, was decreased. Neuronal damage and GFAP-immunoreactive astrocytes were also observed. These results show that focal, transient ischemia alters KPI-APP/APP 695 ratio in cerebral cortex and this shift in APP isoforms could be related to neurodegeneration and/or activation of astrocytes during the ischemic process.

Enhanced release of secreted form of Alzheimer's amyloid precursor protein from PC12 cells by nicotine

There is mounting evidence indicating that overexpression or aberrant processing of amyloid precursor protein (betaAPP) is causally related to Alzheimer's disease. betaAPP is principally cleaved within the amyloid beta protein domain to release a large soluble ectodomain (betaAPPs) that has been known to have a wide range of trophic and protective functions. Activation of phospholipase C-coupled receptors has been shown to increase the release of betaAPPs through protein kinase C and calcium. Here we have examined whether nicotine can modulate the expression and processing of betaAPP in PC12 cells. Treatment of PC12 cells with nicotine increased the release of a carboxyl-terminally truncated, secreted form of betaAPP into the conditioned medium without affecting the expression level of betaAPP mRNA. The effect of nicotine on the secretion of betaAPPs is concentration (>50 microM)- and time (>2 hr)-dependent and attenuated by cotreatment with either mecamylamine, a specific nicotinic receptor antagonist, or EGTA, a calcium chelator, indicating calcium entry through the neuronal nicotinic acetylcholine receptor is essential in enhanced betaAPPs release by nicotine. However, nicotine did not significantly change the amyloid beta protein secretion from Swedish mutant betaAPP-transfected PC12 cells. These results imply that nicotinic receptor agonist might be beneficial in the treatment of Alzheimer's disease by not only supplementing the deficient cholinergic neurotransmission but also stimulating the release of betaAPPs.

Age-related changes in the expression of Alzheimer's beta APP in the brain of senescence accelerated mouse (SAM)-P/10

Patients with Alzheimer's disease (AD) show loss of memory and cognitive deficits the molecular mechanisms of which are not completely known. We examined age-related changes in the expression levels of beta-amyloid precursor protein (beta APP) in the brain of the senescence accelerated mouse (SAM) P/10, which shows age-dependent brain atrophy and impairment in learning and memory, and in the senescence resistant mouse (SAM)-R/1 using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. Levels of both beta APP mRNA and protein increased with age, reaching a peak at 8 months of age in the hippocampus of SAM-P/10. In contrast, beta APP protein level decreased with age in the hippocampus of SAM-R/1 while beta APP mRNA level did not change significantly. Levels of beta APP mRNA and protein showed no change with ageing in other brain regions, including cerebral cortex, thalamus/midbrain and cerebellum brain stem. These results suggest that the beta APP over-expression in the hippocampus might be related to the characteristic memory loss in SAM-P/10.

Purification and characterization of constituent androstenedione 15 alpha-hydroxylase (cytochrome P450(15 alpha AD)) from mouse liver. Sex- and tissue-dependent expression

Hepatic microsomal androstenedione 15 alpha-hydroxylase (i.e.cytochrome P450(15)alpha AD was purified from female CD-1 mice. Protein purification was monitored in eluates from Fractogel, DEAE-Sephacel, and hydroxylapatite columns at heme absorbing 417 nm, by cytochrome P450 content, reactivity to monoclonal antibody against female-specific rat cytochrome P450 2C12, and androstenedione 15 alpha-hydroxylase activity. The catalytic activity for androgens of the purified cytochrome P450(15)alpha AD, exhibiting a high degree of regioselectivity and stereospecificity, was restricted to the 7 alpha- and 15 alpha-hydroxylation of androstenedione, representing, respectively, > 5% and > 93% of the total metabolites. Polyclonal antibodies against cytochrome P450(15)alpha AD exhibited a concentration-dependent and very selective inhibition of hepatic microsomal androstenedione 7 alpha- and 15 alpha-hydroxylation and a 60% inhibition of benzphetamine demethylation, the latter drug appearing to be a much more effective substrate than androgens. Cytochrome P450(15)alpha AD accounted for about 3% of the total P450 in female mouse liver microsomes. The apparent subunit molecular weight of P450(15)alpha AD was 53,000, and the protein appeared as a single band or sodium dodecyl sulfate-polyacrylamide gels. The isoform was intensely expressed in both liver and lung of CD-1 female mice and was female-predominant in the livers of five or eight strains examined; it was sex-independent in the remaining three strains. Amino-terminal sequence analysis indicates that cytochrome P450(15)alpha AD is a member of the murine cytochrome P450 2c subfamily.

Molecular physiology, biochemistry, and pharmacology of Alzheimer's amyloid precursor protein (APP)

The function of APP is not yet known in detail but growing evidence exists that APP may mediate cell interactions with the cell surface or soluble glycoproteins and defense mechanisms in the CNS involving the immune system. We describe here the finding that almost all CD4+ lymphocytes and the majority of CD8+ lymphocytes were positive for A beta and the antibodies against A beta or APP did not inhibit the [3H]-thymidine uptake of mitogen-treated lymphocytes significantly. There were no differences in the A beta immunoreactivity on the cell surface of lymphocytes between Alzheimer's disease (AD) and control samples. Excessive amyloidogenic pathway of APP processing may be the final common pathway involved in the pathogenesis of AD. Thus, the identification of proteases or factors leading to aberrant proteolysis which process APP to yield a variety of potentially amyloidogenic fragments would promise pharmacological targets to develop anti-AD drugs. In attempts to define the proteases or factors which alter the balance between nonamyloidogenic and amyloidogenic processing pathways, our study indicates that thrombin or acetylcholinesterase(AChE)-associated protease may be involved in the amyloidogenic processing pathway of APP in vivo to generate amyloidogenic intermediates linked to amyloid deposition. Highly specific and dose-dependent direct modulation of APP processing by biologically available metal ions including Ca2+, Zn2+, Fe2+/Fe3+ and Al3+ suggest the disrupted metal homeostasis as factors leading to overaccumulation of APP and subsequent aberrant proteolysis utilizing excessive amyloidogenic processing pathway. There is mounting evidence that at least some of the neurotoxicity associated with AD is due to fragments from APP. Most research has focused on the toxic effect and the ion channel activity of A beta in causation of the disease. The possible role of other cleaved products of APP is less clear. We investigated the channel-forming ability of various products of APP when applied to Xenopus oocytes and their neurotoxicity in vitro. CT105 peptide was found to be exceedingly potent at 500 nM concentration in forming nonselective ion channels during application from either outside or inside the oocyte and more toxic than either of the A beta fragments, A beta 25-35, or A beta 1-40. Taken together, these results suggest the possible involvement of CT peptide in inducing the neurotoxicity characteristic of AD through the direct damage on the cell membrane. Therefore, we hypothesize that amyloidogenic CT may make nonselective ion channels or pores in the membrane and may cause neuronal death in the early stage of AD and then further metabolized to more stable and less toxic A beta which may be finally deposited in the brain where it could inflict further toxicity to neurons. Here we report successful inhibition of APP gene expression by antisense oligodeoxynucleotides at the mRNA or the protein level in in vitro and cell culture systems.

Simulataneous isolation of NADPH-cytochrome P-450 reductase and cytochrome P-450 using tentacle ion-exchange chromatography and interspecies comparison of the reductase activity

Using the same initial Fractogel (tentacle) ion-exchange chromatography to isolate murine cytochrome P-450, mouse hepatic NADPH-cytochrome P-450 reductase (EC 1.6.2.4) was simultaneously isolated from solubilized liver microsomes and purified on a DE-52 column to a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme had a molecular mass of 77 kD, and its specific activity was 25.4 mumol.min-1.mg protein-1. Purified constitutive mouse liver NADPH-cytochrome P-450 reductase was successfully reconstituted in vitro with dilauroylphosphatidyl-choline and constitutive purified mouse testosterone 2 alpha-hydroxylase (cytochrome P-450(2)alpha) with an observed activity of 13.8 nmol.min-1.nmol P-450-1. Although the partially purified reductase obtained from the Fractogel column was contaminated by significant levels of two unidentified proteins, it was as equally effective in the reconstituted system as the DE-52-derived purified reductase. Lastly, we found that rat and mouse NADPH-cytochrome P-450 reductases were similarly effective in supporting the catalytic activity of rat cytochrome P-450 2B1, but the murine reductase was 50% more effective than the rat reductase in a reconstituted system containing mouse cytochrome P-450(2)alpha.

Bullous pemphigoid: persistent lesions of eczematous/urticarial erythemas

Two patients with bullous pemphigoid presented with pruritic eczematous or urticarial eruptions on the trunk. These nonbullous lesions had persisted throughout the course of disease with no blistering lesions for more than two years in each patient.