Photorefractive Gunn effect.
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Journal Article↗
Biomedical subjects
D Abraham
Publications and source records attributed to D Abraham.
Strongyloides stercoralis: eosinophil-dependent immune-mediated killing of third stage larvae in BALB/cByJ mice.
Challenge worm survival was significantly reduced when BALB/cByJ mice were vaccinated against Strongyloides stercoralis infective third stage larvae (L3) regardless of whether the challenge infections consisted of systemically migrating L3 or L3 implanted in diffusion chambers. The only cell type that increased in number in diffusion chambers in immunized mice, 1 week after booster immunizations, was the eosinophil, and maximal levels of eosinophils were coincident with parasite killing. Mice were treated with mAb to eliminate IL-5 or granulocytes to assess the role that eosinophils play in larval killing. Treated animals showed no decrease in immunity when challenge infections consisted of systemically migrating L3 administered 3 weeks after booster immunizations. Eosinophil numbers in immunized mice decreased to control levels when measured 3 weeks post-booster immunization, both in diffusion chambers and in the peripheral blood, whereas they were elevated at 1 week after booster immunizations. Direct contact between host cells and L3 was, however, still required for larval killing in immunized hosts 3 weeks after booster immunizations. Elimination of eosinophils by treatment with mAb to IL-5 or granulocytes significantly reduced protective immunity, when L3 were implanted in diffusion chambers at 1 and 3 weeks post-booster. However, as systemically migrating L3 were still killed in immunized, eosinophil-depleted animals, other cell types may play a role in larval destruction. Two human eosinophil granule products were found to be toxic for host-adapted L3+, but had no effect on infective L3, indicating that host-adapted larvae are possible targets for eosinophil-mediated destruction of third stage larvae. These findings suggest that inactivation of eosinophils by mAb treatment abolishes protective immunity to L3 contained within diffusion chambers and that small numbers of eosinophils are sufficient for immune-mediated killing of S. stercoralis L3.
Animals↗
Strongyloides stercoralis: role of antibody and complement in immunity to the third stage of larvae in BALB/cByJ mice.
Mice immunized against Strongyloides stercoralis L3 were shown to kill greater than 90% of challenge larvae contained within diffusion chambers. The objective of the present study was to identify the host components responsible for immunity. Serum from unprotected, control mice and protected, immune mice in doses of 25-500 microliters was transferred into naive mice at the same time and location as larval challenge. Transfer of as little as 50 microliters of immune serum was able to confer protective immunity. The serum-transferred immunity was ablated by excluding cells from the larval microenvironment or by depleting granulocytes through monoclonal antibody treatment in the recipient mice. Specific antibody isotypes were isolated using protein G and isotype-specific affinity columns. The resulting transfer experiments identified IgM as the isotype responsible for protective immunity to S. stercoralis L3. Antibody binding studies in vivo were performed and only IgM bound to the surface of infective L3 and host-derived L3 (L3+) in immune animals. Elevated levels of C3 were also found bound to the surface of L3/L3+ in immune mice. Cobra venom factor treatment of immunized mice to deplete complement completely eliminated C3 binding to the surface of L3/L3+ and ablated immunity. Therefore, IgM, complement, and granulocytes are necessary for immune elimination of S. stercoralis L3/L3+. Identification of antigens recognized by IgM may help select possible vaccine candidates.
Animals↗
Vicia faba as a bioindicator of oil pollution.
In 1990, the Gulf War caused an unprecedented environmental catastrophe. More than 700 oil wells were set on fire, emitting thousands of tons of oxides of nitrogen, sulfur, soot and oil mist at high temperatures. The blazing oil wells and lakes were the major cause of environmental pollution, damaging flora and fauna throughout Kuwait and the surrounding region. We set up this study in order to investigate whether Vicia faba could be used as a bioindicator of oil pollution. Growth parameters of Vicia faba, such as levels of photosynthetic pigments, proteins, free amino acids, phenols, sugars, biomass, moisture and fatty acids, were studied. Levels of total reducible sugars, phenols, proteins, free amino acids and proline were found to be higher in plants grown in hydrocarbon-polluted soil, compared to those grown in control soil. However, biomass, moisture, pheophytin, the 435/415 nm ratio for chlorophylls and the chlorophyll a/carotenoid ratio, were higher in the plants grown in control soil than those grown in polluted soil. Our results indicate that Vicia faba can be used as a bioindicator of pollution and a ratio of the fatty acid C(20:1)/C(18:1) is an important index of environmental oil pollution.
Journal Article↗
Structural and molecular specificity of antibody responses in mice immune to third stage larvae of Onchocerca volvulus.
Immunization of mice with irradiated Onchocerca volvulus infective stage larvae (L3) has been demonstrated to confer protection against challenge infections with these larvae. Additionally, cytokine level measurements and cytokine depletion studies have shown that both IL-4 and IL-5 are important in generating a protective immune response against O. volvulus challenge infections, thus suggesting a dependency of protective immunity on IgG1, IgE and/or eosinophils. In the present study, we examined the humoral responses of immunized mice to O. volvulus L3 antigens. ELISA measurements of total serum antibody levels indicated that IgE was the only antibody isotype elevated in mice immunized with O. volvulus L3. IgM from immunized mice was the only isotype that recognized surface antigens on intact O. volvulus L3. IgG1, IgG3, IgE and IgA recognized internal parasite antigens on O. volvulus L3 frozen sections. Western blot analysis of L3 proteins showed that in serum from mice immunized with O. volvulus L3 IgG1, IgG2a/2b, IgA, and IgE, as well as IgM, recognized unique L3 proteins. Antibodies in serum from L3 immunized mice were able to detect O. volvulus adult antigens in a pattern similar to the recognition found in O. volvulus L3. Some L3 antigens were shared by adults, while other antigens were L3 specific. The ELISA, immunohistochemistry and Western blot findings thus demonstrate a complex pattern of antigen recognition of parasite antigens by antibodies found in mice immune to the L3 of O. volvulus.
Animals↗
[The "neuroleptic threshold"--a review of the literature].
The neuroleptic threshold theory raised the expectation that schizophrenic patients could be treated with an optimal, individual neuroleptic dosage, causing no side effects. Although most existing studies do not fulfill current methodological standards, a few methodologically convincing analyses confirm that good clinical results can be achieved with relatively low dosages (4 mg haloperidol equivalent per day). Thus, the neuroleptic threshold theory and methods related to it deserve further research.
Antipsychotic Agents↗
Eustrongylidiasis--a parasitic infection acquired by eating live minnows.
The objective of this study was to heighten physician awareness of eustrongylidiasis by investigating the epidemiology of this parasitic infection. The nematode Eustrongylides ignotus was recovered surgically from our patient, in whom eustrongylidiasis simulated acute appendicitis. The patient had consumed two live minnows obtained from Big Timber Creek of Belmawr, NJ. The authors determined the E ignotus infestation rate of free-living minnows at this creek. With this data, they approximate the probability of human infection with E ignotus after eating live minnows and attempt to evaluate the hypothesis that eating live minnows may lead to eustrongylidiasis.
Abdomen, Acute↗
Eosinophilic pustular folliculitis (Ofuji disease) in a child.
Eosinophilic pustular folliculitis (EPF) has been described mostly in adults from Japan. From the few reports of children with EPF it is clear that the disease displays the characteristic features, with some clinical differences compared to EPF in adults. We describe the case of an 8-year-old boy with multiple vesicles, pustules, and erythema multiforme-like lesions on the trunk and lower extremities. Results of histopathologic examination revealed subcorneal and intraepidermal pustules, and an inflammatory infiltrate consisting of lymphocytes and eosinophils mainly with a perifollicular distribution. The patient also had impaired chemotaxis, IgG3 subclass deficiency, and elevated IgE levels.
Age of Onset↗
Regression of C6 rat brain tumors by cells expressing an antisense insulin-like growth factor I receptor RNA.
We have previously shown that C6 cells expressing an antisense insulin-like growth factor I receptor (IGF-IR) RNA are no longer tumorigenic in syngeneic rats, protecting them from subsequent subcutaneous tumor challenge and causing regression of established subcutaneous tumors. In the present study, we have investigated the efficacy of this strategy on intracerebrally implanted C6 rat glioblastoma cells. We demonstrate that C6 cells expressing an antisense IGF-IR RNA implanted for 24 h in the subcutaneous tissue of the rats are able to elicit an anti-tumor response in the brain, leading to complete brain tumor regression and long-term survival of the rats. These findings suggest the possibility of therapeutic intervention in human gliomas.
Animals↗
Correlation between apoptosis, tumorigenesis, and levels of insulin-like growth factor I receptors.
We have investigated whether there is a quantitative relationship between the insulin-like growth factor I receptor (IGF-IR), the extent of apoptosis in vivo, and tumorigenesis. C6 rat glioblastoma cells were treated with increasing concentrations of antisense oligodeoxynucleotides to the IGF-IR RNA. The extent of apoptosis in vivo is correlated to the decrease in IGF-IR levels and, in turn, tumorigenesis in nude mice is correlated to the fraction of surviving cells. In syngeneic rats, a host response leads to complete inhibition of tumorigenesis. These findings establish, for the first time on a quantitative basis, the relationship between IGF-IR levels and the extent of apoptosis, as well as the relationship between the initial apoptotic event and the time of appearance of transplantable tumors.
Animals↗
The insulin-like growth factor I receptor protects tumor cells from apoptosis in vivo.
The role of the insulin-like growth factor I receptor (IGF-IR) in programmed cell death has been investigated in vivo in a biodiffusion chamber, where the extent of cell death could be determined quantitatively. We found that a decrease in the number of IGF-IRs causes massive apoptosis in vivo in several transplantable tumors, either from humans or rodents. Conversely, an overexpressed IGF-IR protects cells from apoptosis in vivo. We also show that the same conditions that in vitro cause only partial growth arrest with a minimum of cell death, induce in vivo almost complete cell death. We conclude that the IGF-IR activated by its ligands plays a very important protective role in programmed cell death, and that its protective action is even more striking in vivo than in vitro.
3T3 Cells↗
Scleroderma-derived human fibroblasts retain abnormal phenotypic and functional characteristics following retroviral transduction with the SV40 tsT antigen.
In this study an amphotropic retrovirus has been used to efficiently transduce normal human (NF) and scleroderma (systemic sclerosis; SSc) dermal fibroblasts (SScF) with a sequence encoding a temperature-sensitive mutant of the SV40 large T antigen (tsA58-U19). From the primary outgrowths of skin explants, cultures were generated whose growth was stringently temperature-dependent. When grown at a low, permissive temperature (35 degrees C), both normal and SSc-transduced cells continuously divided with similar doubling times, whereas at a high, nonpermissive temperature (39.5 degrees C), division of both the NF and SScF cells was rapidly arrested. These cells have been passaged more than 50 times, have the typical morphological appearance of fibroblasts, and have retained an anchorage-dependent phenotype. The transduced normal cells (tsT-NF) synthesized the matrix molecules collagen and fibronectin and expressed phenotypic antigens characteristic of their nontransduced counterparts, including MHC Class I, VLA beta 1 (CD29), Hermes 1 (CD44), VLA-4 alpha (CD49d), ICAM-1 (CD54) and LFA-3 (CD58) and the cell surface ectoenzymes neutral endopeptidase (CD10), aminopeptidase N (CD13), and dipeptidyl peptidase IV (CD26). Analysis of the transduced SSc fibroblasts (tsT-SScF) showed that these cells exhibited certain major features of the SSc pathology, notably the abnormally high synthesis of type I collagen, increased expression of ICAM-1, and depressed levels of CD26. Moreover, these phenotypic characteristics were retained even after prolonged culture in vitro. The tsT-SScF cells also retained their responsiveness to cytokines, since interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) both produced a marked increase in ICAM-1 expression. Our findings show that infection of SScF with the SV40 tsT antigen extends the life span of these cells and does not ablate their abnormal phenotypic and functional characteristics.
Antibodies↗
Strongyloides stercoralis: protective immunity to third-stage larvae inBALB/cByJ mice.
A murine model system was developed to study the induction and mechanism of protective immunity to L3 of Strongyloides stercoralis. L3 were implanted in BALB/cByJ mice in diffusion chambers constructed with 0.1- or 2.0-microns-pore-size membranes. Parasites survived equally well regardless or membrane type for 7 days, after which larval survival decreased in diffusion chambers constructed with 2.0-microns-pore-size membranes, which allowed host cells to enter. Survival of S. stercoralis L3 in diffusion chambers implanted in mice was assayed after immunization with live, heat-killed, and homogenized L3. Optimal immunization was achieved with 10,000 live L3, whereby immunized mice eliminated 97% of the larvae either contained within diffusion chambers or free within the tissues of the mouse by 24 hr postinfection. Sera from immunized mice had elevated levels of IgG1, IgM, and IgA parasitic-specific antibody; IgM was the only antibody isotype that recognized surface antigens of L3. Larvae were not killed in immunized mice if contact between host cells and the parasites was prevented. In the peripheral blood and diffusion chamber fluid of immunized mice, eosinophil levels were significantly higher when compared to the levels found in control mice. The rodent model developed in the present study has thus demonstrated that virtually complete immunity can be induced to the L3 of S. stercoralis and that larval killing was found to be associated with the presence of both specific antibody and eosinophils.
Animals↗
Strongyloides stercoralis: complete life cycle in SCID mice.
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Animals↗
Immunity to a challenge infection of Strongyloides stercoralis third-stage larvae in the jird.
Jirds support the entire life-cycle of Strongyloides stercoralis. We therefore used this host as a model to define the mechanism of the immune response to a challenge infection, as well as the parasite stage effected by the response. Jirds given a primary infection of S. stercoralis are resistant to re-infection. The use of implanted diffusion chambers containing larvae showed that the immune response killed the third-stage larvae, and this was confirmed by subcutaneous infections. The larvae of a challenge infection are killed within 48 h, a time period too short to allow for the development of L4 and adult worms. The immune response is dependent on both a serum factor and cells, suggestive of an ADCC type response.
Animals↗
Cerebellar ataxia in coeliac disease--no evidence of a humoral aetiology.
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Aged↗
alpha 4 beta 2 subunit combination specific pharmacology of neuronal nicotinic acetylcholine receptors in N1E-115 neuroblastoma cells.
Pharmacological characteristics of native neuronal nicotinic acetylcholine receptor-mediated ion currents in mouse N1E-115 neuroblastoma cells have been investigated by superfusion of voltage clamped cells with known concentrations of the agonists acetylcholine, nicotine and cytisine, and the antagonists alpha-bungarotoxin and neuronal bungarotoxin. The sensitivity of the nicotinic acetylcholine receptor for agonists followed the agonist potency rank-order: nicotine approximately acetylcholine >> cytisine. The EC50 values of acetylcholine and nicotine are 78 microM and 76 microM, respectively. Equal concentrations of acetylcholine and nicotine induce inward currents with approximately the same peak amplitude whereas cytisine induces much smaller inward currents. Acetylcholine-induced currents are unaffected by high concentrations of alpha-bungarotoxin. Conversely, at 10 and 90 nM neuronal bungarotoxin reduces the amplitude of the 1 mM acetylcholine-induced inward current to 47% and 11% of control values, respectively. Both the agonist potency rank-order and the differential sensitivity to snake toxins of nicotinic receptors in N1E-115 cells are consistent with the known pharmacological profile of alpha 4 beta 2 nicotinic receptors expressed in Xenopus oocytes and distinct from those of all other nicotinic acetylcholine receptors of known functional subunit compositions. All data indicate that the native nicotinic acetylcholine receptor in N1E-115 cells is an assembly of alpha 4 and beta 2 subunits, the putative major subtype of nicotinic acetylcholine receptor in the brain.
1-Methyl-3-isobutylxanthine↗
IL-4- and IL-5-dependent protective immunity to Onchocerca volvulus infective larvae in BALB/cBYJ mice.
A significant reduction in challenge worm survival occurred when BALB/cBYJ mice were vaccinated against Onchocerca volvulus infective third stage larvae (L3) by using irradiated O. volvulus L3. Challenge infections consisted of L3 implanted in diffusion chambers, which were used as a means to contain, and thus efficiently recover, the larvae from the host. The goal of the present study was to describe the mechanism of immune-mediated killing of O. volvulus L3 in diffusion chambers in mice. Direct contact between host cells and parasites was required for killing of larvae in immunized hosts. To define the mechanism of immune-mediated killing in this system, the time of influx of cells and cytokines into the infection site was compared with the time challenge infections were killed. The only cell type that was found to increase in diffusion chambers in immunized mice was eosinophils; maximal levels of eosinophils were coincident with the time of parasite killing. IL-5 was found in diffusion chambers of immunized mice coincident with the time of parasite killing; IL-5 was not found in diffusion chambers recovered from control mice. Significant levels of IFN-gamma were absent in the diffusion chambers of both groups. Immunized mice were treated with mAb to eliminate IL-5 or IL-4 to assess the role these cytokines or their by-products play in larval killing. Elimination of either IL-5 or IL-4 significantly reduced the protective effects of vaccination against larval O. volvulus.
Animals↗