Effects of transforming growth factor-beta (isoforms 1-3) on amyloid-beta deposition, inflammation, and cell targeting in organotypic hippocampal slice cultures

The transforming growth factor-beta (TGF-beta) family consists of three isoforms and is part of a larger family of cytokines regulating differentiation, development, and tissue repair. Previous work from our laboratory has shown that TGF-beta1 can increase amyloid-beta protein (Abeta) immunoreactive (Abetair) plaque-like deposits in rat brain. The aim of the current study was to evaluate all three isoforms of TGF-beta for their ability to affect the deposition and neurotoxicity of Abeta in an organotypic, hippocampal slice culture model of Abeta deposition. Slice cultures were treated with Abeta either with or without one of the TGF-beta isoforms. All three isoforms can increase Abeta accumulation (over Abeta treatment alone) within the slice culture, as determined by ELISA. However, there are striking differences in the pattern of Abetair among the three isoforms of TGF-beta. Isoforms 1 and 3 produced a cellular pattern of Abeta staining that colocalizes with GS lectin staining (microglia). TGF-beta2 produces dramatic Abeta staining of pyramidal neurons in layers CA1-CA2. In addition to cellular Abeta staining, plaque-like deposits are increased by all of the TGF-betas. Although no gross toxicity was observed, morphological neurodegenerative changes were seen in the CA1 region when the slices were treated with Abeta plus TGF-beta2. Our results demonstrate important functional differences among the TGF-beta isoforms in their ability to alter the cellular distribution and degradation of Abeta. These changes may be relevant to the pathology of Alzheimer's disease (AD).

Effect of chloroquine and leupeptin on intracellular accumulation of amyloid-beta (A beta) 1-42 peptide in a murine N9 microglial cell line

Murine N9 microglia accumulated A beta from media containing 0.67 microM A beta within 6 h. In N9 and in primary rat microglia, chloroquine, which disrupts lysosomal pH, increased A beta-induced accumulation of A beta, particularly A beta1-42. Leupeptin similarly enhanced A beta accumulation. The scavenger receptor antagonist fucoidan did not affect acute chloroquine-dependent A beta1-42 accumulation, demonstrating uptake of non-aggregated A beta. After prolonged incubations, chloroquine enhanced A beta multimer (8-12 kDa) accumulation, an effect inhibited by fucoidan. Disruptions of the lysosomal system enhance A beta and its multimer formation. Despite negligible effects of fucoidan on initial A beta uptake, chronic exposure inhibits multimer accumulation, demonstrating a role for scavenger receptor in multimer accumulation.

Mapping of Drosophila mutations using site-specific male recombination

Although recombination does not usually occur in the male Drosophila germline, site-specific recombination can be induced at the ends of P elements. This finding suggested that male recombination could be used to map Drosophila mutations. In this article, we describe the general method and its application to the mapping of two EMS-induced female-sterile mutations, grauzone and cortex. Within two months, the grauzone gene was mapped relative to seven different P-element insertion sites, and cortex was mapped relative to 23 different P-elements. The results allowed us to map grauzone to a region of about 50 kb, and cortex distal to the chromosomal region 33E. These experiments demonstrate that P-element-induced site-specific male recombination is an efficient and general method to map Drosophila autosomal mutations.

The Siemens virtual wedge

A Siemens Virtual Wedge has recently been installed and commissioned at the Northeastern Ontario Regional Cancer Centre. Measurements reported below show that 1) Virtual Wedge factors are within 1.5% of 1; 2) percentage depth doses down to 15 cm for open and virtually wedged fields are identical to within 0.7%; 3) relative cross beam profiles for 60 degrees virtual and physical wedges are very similar except at the toe end where a 5% difference in relative dose has been observed and 4) the peripheral dose from the 60 degrees Virtual Wedge is about half of that from the 60 degrees physical wedge. A clinical protocol requiring combined open and 60 degrees wedged fields has been developed and validated. This protocol, which does not impair the utility of the Virtual Wedge, facilitates the use of on-line portal imaging and significantly reduces the effort required to commission the system.

Refractive changes in chicks with form-deprivation myopia

PURPOSE

To study the refractive changes of form deprivation of myopia.

METHODS

Haisaik chickens were used to establish the animal models of myopia. Monocular eyelids were sutured for form deprivation on the 5th day after chickens birth. The chickens were examined by optometer and the anteroposterior axis, transverse and vertical diameters were measured by verniermicrometer.

RESULTS

Form deprivation leads to myopic refractive abnormality (P < 0.001). The ocular anteroposterior axis (P < 0.005), transverse and vertical diameters lengthen (P < 0.05).

CONCLUSION

Form deprivation is the main cause of the development of myopia.

Disposition of methylenedioxymethamphetamine and three metabolites in the brains of different rat strains and their possible roles in acute serotonin depletion

3,4-Methylenedioxymethamphetamine (MDMA) affects both dopamine and serotonin (5-HT) systems. One of its acute actions is to cause a reversible fall in steady-state brain 5-HT concentrations. To investigate the chemical basis of this acute effect, the brain levels of the parent compound and three major metabolites, 3,4- 3,4-methylenedioxyamphetamine (MDA), 3,4-dihydroxymethamphetamine (DHMA) and 6-hydroxy-3,4-methylenedioxymethamphetamine (6-OHMDMA), were monitored, together with 5-HT levels, over a period of 6 hr in male Sprague-Dawley (SD) rats. The temporal relationships between drug concentrations of both stereoisomers and depletions were evaluated first. There was no correlation between the concentrations of the compounds measured and the extent of 5-HT depletion. Brain levels of MDMA and MDA were higher than plasma levels and exhibited a stereoselectivity in that (-)-MDMA and (+)-MDA levels were higher than those of enantiomers. The relationship between the dose of ((+)-MDMA and reduction in 5-HT levels was next investigated in SD male, SD female, and Dark Agouti (DA) female rats. These animals exhibit different capabilities of MDMA metabolism. There is a lower level of MDA, the N-demethylated metabolite of MDMA, in female SD rats than in males. Female DA rats are deficient in CYP2D isozymes, one of the enzymes responsible for demethylenation of MDMA to DHMA at pharmacological concentrations of substrate. there was a significant accuulation of MDMA in the brain and plasma of DA rats, but their 5-HT depletion was somewhat attenuated. The results indicated that MDMA ++ was apparently not the single, causative agent for the acute 5-HT depletion, which may also involve a metabolite formed by CYP2D.

Differential mRNA transport and the regulation of protein synthesis: selective sensitivity of Purkinje cell dendritic mRNAs to translational inhibition

Although the majority of mRNAs expressed in neurons are confined to the perikaryon, a growing number appear to be transported into dendrites. It is likely that this allows for the local regulation of protein synthesis within discrete subcellular compartments. Here, three different subcellular distribution patterns are demonstrated for four mRNAs that encode proteins highly expressed in Purkinje cells and their dendrites; mRNAs are found in the perikaryon only, perikaryon and proximal dendrite, or perikaryon and proximal plus distal dendrites. Further, it is shown that transport of an mRNA into the dendrites increases its sensitivity to translational inhibition by diphtheria toxin. These data suggest a simple model whereby the transport machinery can regulate the translation of selected mRNAs. Thus, environmental signals that generally affect translational efficiency in concert with the selectivity provided by the transport machinery could provide a means to locally regulate the synthesis of a restricted pool of proteins.

Mutations that perturb poly(A)-dependent maternal mRNA activation block the initiation of development

Translational recruitment of maternal mRNAs is an essential process in early metazoan development. To identify genes required for this regulatory pathway, we have examined a collection of Drosophila female-sterile mutants for defects in translation of maternal mRNAs. This strategy has revealed that maternal-effect mutations in the cortex and grauzone genes impair translational activation and cytoplasmic polyadenylation of bicoid and Toll mRNAs. Cortex embryos contain a bicoid mRNA indistinguishable in amount, localization, and structure from that in wild-type embryos. However, the bicoid mRNA in cortex embryos contains a shorter than normal polyadenosine (poly(A)) tail. Injection of polyadenylated bicoid mRNA into cortex embryos allows translation demonstrating that insufficient polyadenylation prevents endogenous bicoid mRNA translation. In contrast nanos mRNA, which is activated by a poly(A)-independent mechanism, is translated in cortex embryos, indicating that the block in maternal mRNA activation is specific to a class of mRNAs. Cortex embryos are fertilized, but arrest at the onset of embryogenesis. Characterization of grauzone mutations indicates that the phenotype of these embryos is similar to cortex. These results identify a fundamental pathway that serves a vital role in the initiation of development.

Characterization of proteins in detergent-resistant membrane complexes from Madin-Darby canine kidney epithelial cells

We previously isolated detergent-resistant membrane complexes (DRMs) that were not solubilized after extraction of Madin-Darby canine kidney cells with Triton X-100 on ice. The complexes were rich in glycosphingolipids, cholesterol, and glycosylphosphatidylinositol (GPI)-anchored proteins. In this study, we examined the protein composition of DRMs and further characterized the detergent solubility of these structures. Eight to ten cell-surface proteins, including proteins from both apical and basolateral membranes, were recovered in DRMs. Most DRM proteins, however, were not exposed to the surface of whole cells, and we did not detect the complex of cell-surface proteins described by Sargiacomo et al. in a similar study [Sargiacomo, M., et al. (1993) J. Cell Biol. 122, 789-807]. Almost all proteins in DRMs were solubilized by Triton X-100 at temperatures above 30 degrees C or by octyl glucoside on ice. In contrast, a GPI-anchored protein, placental alkaline phosphatase, was mostly solubilized by Triton X-100 after extraction at 10 degrees C. This protein was insoluble in ice-cold Triton X-100 when first delivered to the plasma membrane and remained so for at least 6 h after synthesis. A fraction of the lipids in DRMs remained insoluble after extraction with Triton X-100 at 37 degrees C. DRM lipids were not solubilized by octyl glucoside, suggesting that this detergent selectively extracts proteins from DRMs.

Local control of granule cell generation by cerebellar Purkinje cells

Cerebellar Purkinje cells were ablated by the specific expression of diphtheria toxin in these cells in transgenic mice. Purkinje cell degeneration during early postnatal development shows a zonally restricted pattern which has been exploited in order to look for local secondary effects. The most obvious early effect is the alignment of gaps in the Purkinje cell layer with dramatically thinned zones in the overlying EGL, the germinal layer from which granule cells are generated. Within these EGL zones in the transgenic mutant, markers that distinguish matrix from mantle cells demonstrate a preferential loss of the proliferative cells. Comparison of BrdU incorporation in the mutant vs wild-type confirms the reduction in proliferation. In the mutant, in situ labeling of DNA fragmentation associated with apoptotic cell death shows abundant labeling of granule cells that have exited the EGL, but not of progenitor cells in the EGL. Thus, although a trophic role for Purkinje cells has been well documented, these observations further suggest a mitogenic role which can be exerted locally.

The normal Langerhans cell and the LCH cell

The epidermal Langerhans cell is the bone marrow-derived dendritic, antigen-presenting cell of the skin. It is characterised by a unique intracytoplasmic organelle--the Birbeck granule--and constitutively expresses class II MHC molecules and the CD1a glycoprotein. The Langerhans cell represents one of the most potent antigen-presenting cells of the body, and fulfils an important role in detecting foreign antigen entering the body through the skin and in immune surveillance. The distribution of Langerhans cells is restricted to the skin, lymph nodes, bronchial mucosa and thymus. The discovery by Nézelof in 1973 that the lesional cells in the disease then called 'Histiocytosis X' contained Birbeck granules established the close relationship between the Langerhans cell and this disease and led ultimately to the adoption of the name Langerhans cell histiocytosis to replace the older term. The LCH cell expresses the phenotype of a Langerhans cell apparently 'fixed' at an early stage of cell activation. The LCH cell is, however, functionally defective in antigen presentation, and the tissue distribution of the disease--affecting bone, skin, lymph node, lung, liver, spleen, CNS, gastro-intestinal tract and bone marrow--is quite different from the normal distribution of the Langerhans cell. Studies are now under way throughout the world to investigate the relationship between the normal Langerhans cell and the LCH cell. Specifically we need to identify whether the LCH cell is a cell arrested at a specific time in normal Langerhans cell ontogeny or if it represents a response to a biological insult to the mature Langerhans cell or its precursors.

Specific A+T-rich repetitive DNA sequences in maxicircles from wildtype Leishmania mexicana amazonensis and variants with DNA amplification

To explain the low cross-hybridization between kinetoplast DNA maxicircles of Leishmania parasites that show DNA amplification and those of parasites without DNA amplification, we isolated and cloned two maxicircle fragments, one specific to each group of parasites. The cloned fragment from wildtype L. m. amazonensis (MbpW94) and that from an arsenite-resistant variant with DNA amplification (MpbA29) hybridized only to maxicircles from parasites of the group from which the fragment was originally derived. Both fragments were A+T-rich, tandemly repeated, and lacked long conserved open reading frames and transcriptional products. MpbW94 (685 bp) was harbored in a segment of roughly 12 kb in maxicircles of wildtype parasites and of an arsenite-resistant variant without DNA amplification, while MbpA29 (1121 bp) occupied a 6- to 7-kb segment of maxicircle DNA in arsenite- and tunicamycin-resistant variants with DNA amplification. These maxicircle DNA segments appear to resemble previously described maxicircle divergent regions of other kinetoplastids. The presence of these specific sequences allows differentiation between maxicircles of drug-resistant L. m. amazonensis with DNA amplification and those of parasites without DNA amplification and helps explain the low cross-hybridization between maxicircles of the two parasite groups. Furthermore, these sequences allow the study of the kinetics of the changeover of A+T-rich regions of maxicircles during the transition period from one maxicircle type to the other.

A technique for the evaluation of a missing tissue compensator system

A two dimensional approach to the evaluation of a missing tissue compensator system has been developed and implemented. Quantitative descriptors of the dose area histograms generated by scanning films irradiated under a variety of compensated and uncompensated conditions are proposed. The method has been found to be useful during the acceptance testing of a commercial compensator system and the results of this exercise are presented.

Purification of functional active epidermal Langerhans cells: a simple and efficient new technique

Our knowledge of the functional activity of the epidermal Langerhans cell has been severely hampered by the lack of an easy method of purification of these cells that is both efficient and reproducible. In the present study we have used immunomagnetic beads directly conjugated to an IgM class mouse anti-human human leukocyte antigen DR monoclonal antibody to positively select human Langerhans cells from an epidermal cell suspension. Cells were then treated with a high-affinity polyclonal anti-mouse immunoglobulin that detached the beads by competing with the antigen for the antigen-binding site on the monoclonal antibody. This procedure allowed removal of the immunomagnetic beads, leaving Langerhans cells free from bound antibody. Recovery of Langerhans cells ranged from 40 to 80% of the starting number of Langerhans cells. The resulting cells were up to 99% CD1a positive and showed potent functional activity in the allogeneic mixed epidermal cell - lymphocyte reaction. Keratinocytes were shown to exert a profound inhibitory effect on Langerhans cell function that could not be prevented by indomethacin. This method is technically simple and allows good recovery of a highly purified population of Langerhans cells that are functionally active.

[Separation of 20(S)-ginsenoside-Rg2 and its 20(R) epimer by reversed phase low pressure column (Rp-18) chromatography]

20(S)-Ginsenoside-Rg2 and its 20(R) epimer were successfully separated using reversed-phase low pressure column (Rp-18) chromatography. The method has proved very convenient and rapid.

Video techniques for on-line portal imaging

The application of on-line portal imaging techniques to the verification of treatment precision is reviewed. The design parameters for a video portal imaging system are described, and the optimization of image quality is discussed with particular emphasis on photon noise. On-line images are presented for a head phantom imaged on a 4 MV linac, and compared with a conventional portal film. The relative advantages of an on-line system are compared with conventional portal film analysis.

The incidence of immunosuppression-related skin disease in long-term transplant patients

One hundred and twenty-one patients who had received a renal allograft between 4 months and 21 years previously (mean +/- SD, 71 +/- 62 months) were studied. Seventy-two patients were conventionally immunosuppressed with azathioprine and prednisolone, and 36 had been exposed to the current regime of cyclosporine, azathioprine, and prednisolone. Forty-five patients had viral warts, of whom 20 had more than 10 warts. The presence of viral warts was significantly associated with pale skin type, excess sun exposure, and with duration of allograft. Viral warts were significantly more common in those on conventional immunosuppressive therapy, but this could be solely a reflection of the difference in duration of transplant between the 2 groups. Twelve patients were found to have developed dysplastic or neoplastic skin lesions since transplantation. The incidence of dysplasia increased with increasing age and was significantly associated with pale skin type, excess sun exposure, and duration of allograft. Despite the shorter duration of treatment in those on the new treatment regime, there was no difference between the 2 groups in the proportion of patients with dysplastic skin lesions. Immunosuppression-related skin disease may be a significant problem in allograft recipients in this country, and we suspect that patients taking cyclosporine will have similar problems to those on conventional immunosuppressive drugs alone. Immunosuppressed patients should be advised to avoid sun exposure, to use sunscreens, and should be monitored carefully for the development of dysplastic lesions.

Double-blind comparison of terfenadine, chlorpheniramine, and placebo in the treatment of chronic idiopathic urticaria

The efficacy of terfenadine, a nonsedating H1 antihistamine, in the management of chronic idiopathic urticaria was compared with chlorpheniramine and placebo in a parallel multicenter trial. Subjects with symptoms of hives for 3 days per week for at least 6 weeks were initially screened and admitted if no identifiable cause for symptoms could be determined. Patients entered a single-blind placebo period, and if hives of moderate severity were present for at least 3 days during the week, they were randomly assigned in a double-blind fashion to take terfenadine, 60 mg twice daily, chlorpheniramine, 4 mg three times a day, or placebo for 6 weeks. Data were analyzed for 122 patients. Those patients receiving both active treatments noted significant improvement in symptoms: pruritus, redness, number of hives, and waking hours during which hives were present, at the end of the first day of therapy. Symptom control by terfenadine was statistically superior to placebo during all 6 weeks, as rated by both patients and investigators. However, statistical significance was not achieved for chlorpheniramine at all observation points. Diphenhydramine was permitted as a relief medication for refractory symptoms and was taken by 52% of subjects receiving placebo, 26% taking chlorpheniramine, and only 9% of patients who were receiving terfenadine. In addition to providing superior symptom control, terfenadine caused less drowsiness and fatigue than chlorpheniramine. Terfenadine is a useful therapeutic agent for primary management of chronic idiopathic urticaria.

Induction of an immature T-cell phenotype in malignant helper T cells by cocultivation with epidermal cell cultures

The possible inductive effect of epidermal cells on T-cell maturation has been examined employing an in vitro cocultivation technique. Mononuclear cells from 6 patients with cutaneous T-cell lymphoma (CTCL) and from 12 healthy volunteers were studied. In the 6 CTCL patients, all showed an expansion of the helper T-cell subpopulation and in one patient with leukemic CTCL, there was almost complete replacement of peripheral blood mononuclear cells by malignant cells with a helper T-cell phenotype. Epidermal cells derived from normal human skin were cultured to confluent monolayers, and were cocultivated with the mononuclear cells from CTCL patients or normal controls for 48 h at a density of 10(6)/ml. Following cocultivation, the surface phenotype of the cells from the 12 healthy volunteers and 5 of the patients with CTCL showed no significant phenotypic change. In the patient with leukemic CTCL, however, the surface phenotype of the malignant T cells had changed, with the acquisition of the T6 antigen by the majority of the cells. Cells cocultivated in medium alone and with human fibroblast monolayers showed no change in surface phenotype. The malignant T cells from the leukemic CTCL patient failed to react in a mixed lymphocyte culture to lymphocytes from 2 different healthy donors, and showed no phenotypic change following culture with these lymphocytes, indicating that the phenotypic change seen was not due to allogeneic stimulation.

The repair of psoralen monoadducts by the Escherichia coli UvrABC endonuclease

We have examined the interactions of UvrABC endonuclease with DNA containing the monoadducts of 8-methoxypsoralen (8-MOP) and 4,5',8-trimethylpsoralen (TMP). The UvrA and UvrB proteins were found to form a stable complex on DNA that contains the psoralen monoadducts. Subsequent binding of UvrC protein to this complex activates the UvrABC endonuclease activity. As in the case of incision at pyrimidine dimers, a stable protein-DNA complex was observed after the incision events. For both 8-MOP and TMP, the UvrABC endonuclease incised the monoadduct-containing strand of DNA on the two sides of the monoadduct with 12 bases included between the two cuts. One incision was at the 8th phosphodiester bond on the 5' side of the modified base. The other incision was at the 5th phosphodiester bond 3' to the modified base. The UvrABC endonuclease incision data revealed that the reactivity of psoralens is 5'TpA greater than 5'ApT greater than 5'TpG.

The Identification of Rubber Compounding Ingredients by Using Thin Layer Chromatography

TLC is a quick, easy method to the identification of rubber compounding ingredients. Both silica gel absorbent and C18 absorbent are suitable for these identifications. With the mobile phases used in this study, a better separation of antioxidants is possible using silica gel absorbent. Work should be continued on finding suitable mobile phases for the C18 absorbent, since the Rf values are more reproducible. For those separations that require a separation of compounds of varying molecular weight, the C18 absorbent is superior to silica gel absorbent. The visualization systems that have been developed for use with silica gel absorbent are suitable for use with C18 absorbent. These systems give the same colors for either absorbent.