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L H Kasper

Publications and source records attributed to L H Kasper.

At least 19 recordsLinked to original sources
PubMed2004

Brain activation patterns associated with working memory in relapsing-remitting MS.

BACKGROUND: Patients with multiple sclerosis (MS) show changes in brain activation patterns during visual and motor tasks that include decreases in the typical local network for a function and increases in other brain regions. OBJECTIVE: To determine whether brain activation patterns associated with working memory are affected by MS. METHODS: Activation of working memory circuitry was examined using an fMRI n-back task in adults with mild relapsing-remitting MS (RRMS; n = 10) and demographically matched healthy controls (n = 10). RESULTS: Group differences in brain activation emerged during both low- and high-demand conditions (p < 0.001). Overall, patients showed less activation than controls in core prefrontal and parietal regions of working memory circuitry, and greater activation in other regions within and beyond typical working memory circuitry, including bilateral medial frontal, cingulate, parietal, bilateral middle temporal, and occipital regions. CONCLUSIONS: Relative to controls, patients with mild RRMS showed shifts in brain activation patterns within and beyond typical components of working memory circuitry.

Adult↗
PubMed2004

Immune responses of different mouse strains after challenge with equivalent lethal doses of Toxoplasma gondii.

Most immunological studies that utilize different strains of inbred mice following T. gondii infection fail to compensate for differences in host susceptibility to the size of the parasite innoculum. To address this concern, susceptible C57BL/6 and resistant CBA/J mice were orally infected with either an equivalent 50% lethal dose (LD50) of brain cysts of the 76K strain of T. gondii (15 cysts in C57BL/6, 400 cysts in CBA/J) or the same dose of parasites in each mouse strain. C57BL/6 mice receiving 400 cysts (LD50 of CBA/J mice) died post infection, whereas CBA/J mice that received 15 cysts (LD50 of C57BL/6 mice) survived. Parasite loads in the brains and serum Toxoplasma-specific IgG1 titers of LD50-infected C57BL/6 mice were significantly higher than those in LD50- or 15 cysts-infected CBA/J mice, whereas splenocyte proliferation to Toxoplasma antigen and the percentage of CD8 alpha+ T cells were reduced in LD50-infected C57BL/6 mice. In contrast, serum IgG2a and IgM titers, the percentage of gamma delta T cells and IFN-gamma expression of spleen of LD50-infected CBA/J mice were higher than those of either 15 cysts-infected CBA/J mice or LD50-infected C57BL/6 mice. These observations demonstrate that the immune response between LD50-infected C57BL/6 and CBA/J mice was more prominent when compared to C57BL/6 or CBA/J mice receiving the same parasite inoculum. These observations would suggest that caution must be excersized in the planning and interpretation of data when the size of the parasite inoculum has not been adjusted for mouse strain.

Animals↗
PubMed2004

Co-infection of malaria and gamma-herpesvirus: exacerbated lung inflammation or cross-protection depends on the stage of viral infection.

In order to study the interaction between a gamma-herpesvirus and malaria we established a co-infection model that involves infection of mice with murine gamma-herpesvirus (MHV-68) and Plasmodium yoelii non-lethal strain (PYNL). To investigate the interaction between acute malaria and the lytic stage of MHV-68, the timing of infections was chosen such that the peak virus and parasite burdens would be present at the same time. Under this condition, we observed significant mortality in co-infected mice and aggressive lung inflammation with a marked influx of neutrophils and megakaryocytes. If mice were latently infected with MHV-68 and then co-infected with malaria we noticed significantly less viral load and parasitaemia. Using MHC/peptide tetramer staining we found that acute malaria reduces the anti-MHV-68 CD8+ T cell response in the animals that develop severe disease. Our study provides important fundamental information, which will be of use when devising strategies to combat infections with more than one agent, a situation that often occurs naturally.

Acute Disease↗
PubMed2001

Detection of IgG antibodies to Neospora caninum and Toxoplasma gondii in dogs examined in a veterinary hospital from Brazil.

A total of 163 dogs with neuromuscular, respiratory and/or gastrointestinal disorders, was admitted at the Veterinary Hospital, Federal University of Uberlândia, Brazil, and submitted to serology for Toxoplasma gondii and Neospora caninum. Assays for T. gondii included indirect haemagglutination (IHA), indirect fluorescent antibody (IFAT-Tg), immunoenzymatic (ELISA), and immunoblotting (IB-Tg). Assays for N. caninum included IFAT-Nc and immunoprecipitation (IP-Nc). Based on concordant results by three serological tests (IHA, IFAT-Tg and ELISA) for T. gondii, and divergent results further confirmed by IB-Tg for reactivity to TgSAG1, the 163 sera were divided into two groups: 59 (36%) Tg-seropositive samples and 104 (64%) Tg-seronegative samples. Antibodies to Neospora were detected in 11 (6.7%) out of 163 analyzed dog sera, with 5 (3.1%) samples reactive to both parasites (Tg+/Nc+), and 6 (3.7%) reactive only to Neospora (Tg-/Nc+). Antibodies only to T. gondii were found in 54 (33%) samples. Among the 11 Neospora-positive sera analyzed by IB-Tg, the five sera Tg+/Nc+ showed strong reactivity to Toxoplasma antigens, especially to TgSAG1 (p30). No reactivity was observed to TgSAG1 in the six samples Tg-/Nc+. By IP-Nc, two highly immunodominant antigens (29 and 35kDa proteins) were recognized by all 11 IFAT-Nc positive sera. Our results suggest that the infection by N. caninum can be concomitantly present in dogs from this area, although less common, and therefore should be considered in the differential clinical diagnosis with T. gondii in dogs presenting neuromuscular, respiratory and/or gastrointestinal disorders.

Animals↗
PubMed2001

Disruption of the FG nucleoporin NUP98 causes selective changes in nuclear pore complex stoichiometry and function.

The NUP98 gene encodes precursor proteins that generate two nucleoplasmically oriented nucleoporins, NUP98 and NUP96. By using gene targeting, we have selectively disrupted the murine NUP98 protein, leaving intact the expression and localization of NUP96. We show that NUP98 is essential for mouse gastrulation, a developmental stage that is associated with rapid cell proliferation, but dispensable for basal cell growth. NUP98-/- cells had an intact nuclear envelope with a normal number of embedded nuclear pore complexes. Typically, NUP98-deficient cells contained on average approximately 5-fold more cytoplasmic annulate lamellae than control cells. We found that a set of cytoplasmically oriented nucleoporins, including NUP358, NUP214, NUP88, and p62, assembled inefficiently into nuclear pores of NUP98-/- cells. Instead, these nucleoporins were prominently associated with the annulate lamellae. By contrast, a group of nucleoplasmically oriented nucleoporins, including NUP153, NUP50, NUP96, and NUP93, had no affinity for annulate lamellae and assembled normally into nuclear pores. Mutant pores were significantly impaired in transport receptor-mediated docking of proteins with a nuclear localization signal or M9 import signal and showed weak nuclear import of such substrates. In contrast, the ability of mutant pores to import ribosomal protein L23a and spliceosome protein U1A appeared intact. These observations show that NUP98 disruption selectively impairs discrete protein import pathways and support the idea that transport of distinct import complexes through the nuclear pore complex is mediated by specific subsets of nucleoporins.

Active Transport, Cell Nucleus↗
PubMed2001

Cerebral malaria in mice: interleukin-2 treatment induces accumulation of gammadelta T cells in the brain and alters resistant mice to susceptible-like phenotype.

In this study, we report that infection with Plasmodium yoelii 17XL, a lethal strain of rodent malaria, does not result in death in the DBA/2 strain of mice. In contrast to BALB/c mice, DBA/2 mice developed significantly less parasitemia and never manifested symptoms of cerebral malaria (CM) on infection with this parasite. Moreover, the histological changes evident in the brain of susceptible BALB/c were absent in DBA/2 mice. Interestingly, the resistant DBA/2 mice when treated with recombinant interleukin (IL)-2, were found to develop CM symptoms and the infection became fatal by 6 to 8 days after infection. This condition was associated with an augmented interferon-gamma and nitric oxide production. Unexpectedly, IL-10 levels were also elevated in IL-2-treated DBA/2 mice during late stage of infection (at day 6 of infection) whereas the inverse relationship between IL-10 and interferon-gamma or nitric oxide was maintained in the early stage of infection (at day 3 after infection). The level of tumor necrosis factor-alpha production was moderately increased in the late phase of infection in these mice. Histology of brain from IL-2-treated mice demonstrated the presence of parasitized erythrocytes and infiltration of lymphocytes in cerebral vessels, and also displayed some signs of endothelial degeneration. Confocal microscopical studies demonstrated preferential accumulation of gammadelta T cells in the cerebral vessels of IL-2-treated and -infected mice but not in mice treated with IL-2 alone. The cells recruited in the brain were activated because they demonstrated expression of CD25 (IL-2R) and CD54 (intercellular adhesion molecule 1) molecules. Administration of anti-gammadelta mAb prevented development of CM in IL-2-treated mice until day 18 after infection whereas mice treated with control antibody showed CM symptoms by day 6 after infection. The information concerning creating pathological sequelae and death in an otherwise resistant mouse strain provides an interesting focus for the burden of pathological attributes on death in an infectious disease.

Animals↗
PubMed2001

Cryptogenic epilepsy: an infectious etiology?

PURPOSE: Cryptogenic epilepsy, the group of epilepsy syndromes for which an etiology is unknown, comprises approximately 20% of all epilepsy syndromes. We selected patients in this subgroup of epilepsy and tested them for evidence of Toxoplasma gondii IgG antibodies by the enzyme-linked immunosorbent assay. T. gondii is found in up to 20% of the U.S. population forming dormant brain cysts in the latent bradyzoite form. We investigated the hypothesis that dormant T. gondii infection might be associated with cryptogenic epilepsy. METHODS: We selected patients with cryptogenic epilepsies and tested them for evidence of T. gondii IgG antibodies by the enzyme-linked immunosorbent assay. A control group was also tested for comparison. RESULTS: We have found a statistically-significant elevation of T. gondii antibodies among cryptogenic epilepsy patients as compared to controls [59% increase in optical density (OD), p = 0.013]. This association persisted after adjustment for subjects' gender and age in a multiple logistic regression model; however, it was no longer as statistically significant. CONCLUSIONS: Our results suggest that chronic T. gondii infection with brain cysts may be a cause of cryptogenic epilepsy.

Adult↗
PubMed2001

Murine ileitis after intracellular parasite infection is controlled by TGF-beta-producing intraepithelial lymphocytes.

BACKGROUND & AIMS: Acute inflammatory ileitis occurs in susceptible (C57BL/6) mice after oral infection with Toxoplasma gondii. Overproduction of interferon (IFN)-gamma and synthesis of nitric oxide mediate the inflammation. We evaluated the role of transforming growth factor (TGF)-beta produced by intraepithelial lymphocytes (IELs) in this process. METHODS: We analyzed the histologic and immunologic consequences of adoptive transfer of antigen-primed IELs into susceptible mice treated with anti-TGF-beta before oral challenge with T. gondii cysts. An in vitro coculture of enterocytes and IELs assessed the production of chemokines and cytokines in the presence of anti-TGF-beta. RESULTS: Antigen-primed IELs prevent acute ileitis in susceptible mice that is reversed with anti-TGF-beta. Resistant mice (CBA/J) develop ileitis after treatment with anti-TGF-beta. Antigen-primed IELs can induce systemic immunosuppression as measured by depressed IFN-gamma production. In vitro, primed IELs reduce the production of inflammatory chemokines by infected enterocytes and IFN-gamma by splenocytes. CONCLUSIONS: Regulation of the ileal inflammatory process resulting from T. gondii is dependent on TGF-beta-producing IELs. The IELs are an essential component in gut homeostasis after oral infection with this parasite.

Animals↗
PubMed2001

Identification and role of thiols in Toxoplasma gondii egress.

The nucleoside triphosphate hydrolase of Toxoplasma gondii is a potent apyrase that is secreted into the parasitophorous vacuole where it appears to be essentially inactive in an oxidized form. Recent evidence shows that nucleoside triphosphate hydrolase can be activated by dithiothreitol in vivo. On reduction of the enzyme, there is a rapid depletion of host cell ATP. Previous results also demonstrate a dithiothreitol induced egress of parasites from the host cell with a concurrent Ca2+ flux, postulated to be a consequence of the release of ATP-dependent Ca2+ stores within the tubulovesicular network of the parasitophorous vacuole. Reduction of the nucleoside triphosphate hydrolase appears crucial for its activation; however, the exact mechanism of reduction/activation has not been determined. Using a variety of techniques, we show here that glutathione promoters activate a Ca2+ flux and decrease ATP levels in infected human fibroblasts. We further show the in vitro activation of nucleoside triphosphate hydrolase by endogenous reducing agents, one of which we postulate might be secreted into the PV by T. gondii. Our findings suggest that the reduction of the parasite nucleoside triphosphate hydrolase, and ultimately parasite egress, is under the control of the parasites themselves.

Acetylcysteine↗
PubMed2001

Apoptosis within mouse eye induced by Toxoplasma gondii.

OBJECTIVE: To investigate apoptosis induced by Toxoplasma gondii (T. gondii) in eyes of C57BL/6 (B6) mice. METHODS: Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) technique and pathological changes within eyes were analyzed at different time points after intraocular inoculation of either 50 or 500 of tachyzoites. RESULTS: In eyes that received 50 tachyzoites, a few apoptotic inflammatory cells in the anterior chamber and keratocytes in the cornea were seen at days 1 and 2, but no apoptosis was detected 4 days after inoculation. Significantly greater apoptosis of inflammatory cells was observed in the anterior chamber and in the vitreous of eyes injected with 500 parasites. Apoptosis of inflammatory cells in the anterior chamber and of keratocytes in the cornea was seen at day 1. The apoptotic stromal keratocytes strikingly increased at day 4. There were a number of apoptotic inflammatory cells in the vitreous at day 2, and a few apoptotic retinal cells along the internal limiting membrane and the nerve fiber layer of the retina 4 days after inoculation. CONCLUSION: These results suggest that apoptosis of inflammatory cells infiltrated eye infected with this parasite may be a mechanism of eliminating the organism.

Animals↗
PubMed2000

Production of macrophage-activated killer cells for targeting of glioblastoma cells with bispecific antibody to FcgammaRI and the epidermal growth factor receptor.

OBJECTIVE: The aim was to determine the ability of macrophage-activated killer cells (MAK cells) obtained from peripheral blood of normal volunteers to kill glioblastoma multiforme (GBM) cell lines. Another goal was to investigate whether a bispecific antibody (bsAb) MDX-447, recognizing the high-affinity Fc receptor for IgG (FcgammaRI) and epidermal growth factor receptor (EGFR), would enhance MAK cell tumoricidal activity. METHODS: Monocytes, from leukapheresis product, were isolated by countercurrent elutriation and differentiated into MAK cells by culture with granulocyte/macrophage-colony-stimulating factor, vitamin D3 and interferon gamma. Cells were checked for sterility, endotoxin and phenotypic markers. MAK cell functional activity was measured by a flow-cytometric phagocytosis assay. Target cells, a carcinoma cell line and two glioma cell lines expressing EGFR, were stained with PKH-26. MAK cells were labeled with fluorescein-conjugated anti-CD14. Combined effectors, targets and bsAb were incubated and the percentage of MAK cells with phagocytosed targets was determined by flow cytometry. CONCLUSION: We demonstrate that a large number of highly purified monocytes, isolated from peripheral blood, can be differentiated into MAK cells for use as an adjuvant for cancer treatment. After culture these cells are sterile, endotoxin-free and comprise more than 95% MAK cells. Increased amounts of CD14, CD64 and HLA-DR, which are characteristics of macrophage activation, were expressed. MAK cells were extremely phagocytic in comparison to monocytes, even in the absence of bsAb. Moreover, bsAb enhanced the tumoricidal activity of elutriated MAK cells targeted against GBM cell lines. Therefore, intracavity MAK cells armed with MDX-447 could be an effective adoptive immunotherapy for EGFR-positive GBM.

Adjuvants, Immunologic↗
PubMed2000

Attachment of Toxoplasma gondii to a specific membrane fraction of CHO cells.

We have observed previously that attachment of Toxoplasma gondii to synchronized host cells is considerably increased at the mid-S phase (4 h postrelease). Synchronized CHO host cells at the mid-S phase were fractionated by molecular weight, and the antigens were used to produce a panel of polyclonal mouse antisera. The polyclonal antisera raised against fraction 4 with molecular mass ranging approximately from 18 to 40 kDa significantly reduced attachment to mid-S-phase host cells. Immunofluorescence assays demonstrated strong reactivity to mid-S-phase host cells and identified a number of potential receptors on Western blots. These data indicate that there is a specific host membrane receptor for parasite attachment that is upregulated during the mid-S phase of the host cell cycle.

Animals↗
PubMed2000

Sequential analysis of cell differentials and IFN-gamma production of splenocytes from mice infected with Toxoplasma gondii.

To assess the relationship between the changes of cellular components and the production of Th1 cytokine in the immune tissue, inbred C57BL/6 mice were orally infected with 40 cysts of 76K strain of Toxoplasma gondii. The sequential change of cell differentials and IFN-gamma production of splenocytes were analyzed by Diff-Quik stain and RT-PCR. There were no significant proportional changes of cellular components of splenocytes until day 4 postinfection (PI) as compared to those of day 0, and the relative percentage of macrophages and neutrophils/eosinophils increased significantly (p < 0.01) thereafter. The expression of IFN-gamma mRNA of CD3- cells was observed from day 1 PI at a low level. However, IFN-gamma production of CD3+ cells increased significantly from day 4 PI (p < 0.01) which progressively increased thereafter. These findings provide the relative percentages of granulocytes and macrophages were increased in conjunction with increase of total number of splenocytes after oral infection with T. gondii in the susceptible murine hosts, and lymphocytes were the major cellular components and the important source of IFN-gamma.

Animals↗
PubMed1999

Immunization with heat-killed Toxoplasma gondii stimulates an early IFN-gamma response and induces protection against virulent murine malaria.

In this study, we describe protection of BALB/c mice by immunization with heat-killed T. gondii tachyzoites against infection with Plasmodium yoelii 17XL which causes cerebral malaria and death in mice by day 7-8 post infection. Immunization resulted significant reduction in parasitemia at the peak period of infection. Protection induced by heat-killed T. gondii was associated with marked increase in NK cell number and IFN-gamma mRNA expression early in the infection. The level of IFN-gamma or TNF-alpha was found to diminish in T. gondii-treated mice as the infection progressed to the late stage. This declined response of IFN-gamma or TNF-alpha was associated with marked increase in the expression of IL-10, a counterregulatory cytokine. Pretreatment of mice with live T. gondii induced poor level of protection as compared with that of heat-killed parasites. Mice that received P. yoelii infection alone, had an elevated IFN-gamma response in the late stage of infection. Development of cerebral malaria in untreated mice was accompanied by an augmented production of TNF-alpha and nitric oxide (NO), the proinflammatory mediators. These findings suggest that nonspecific immunization with T. gondii leads to restoration of an early IFN-gamma response in P. yoelii-infected mice and in the establishment of an immunoregulatory mechanism that effectively antagonizes the disease-promoting effects of proinflammatory cytokines in the late phase of infection.

Animals↗
PubMed1999

Intraepithelial lymphocytes traffic to the intestine and enhance resistance to Toxoplasma gondii oral infection.

Toxoplasma gondii Ag-primed intraepithelial lymphocytes (IEL) from the mouse intestine have been shown to be protective against an lethal parasite challenge when adoptively transferred into recipient mice. In the present study, we observed that Ag-primed IEL traffic to the intestine of naive mice following i.v. administration. Primed and CD8beta+ IEL were the most efficient cells at homing to the host organ. In congenic mice, IEL migrated from intestine within several hours posttransfer. On Ag reexposure, the primed IEL return to the intestine where they enhance resistance as determined by reduction in the number of brain cysts. Treatment of recipient mice with anti-alpha4 and anti-alphaE Abs partially inhibited IEL intestinal homing. The Ab treatment dramatically impaired resistance to a subsequent oral infection. These finding indicate that lymphocyte homing is an important parameter in establishing long term immunity to recurrent infection with this parasite.

Adoptive Transfer↗
PubMed1999

CD8+ CTLs are essential for protective immunity against Encephalitozoon cuniculi infection.

Encephalitozoon cuniculi is a protozoan parasite that has been implicated recently as a cause of opportunistic infection in immunocompromised individuals. Protective immunity in the normal host is T cell-dependent. In the present study, the role of individual T cell subtypes in immunity against this parasite has been studied using gene knockout mice. Whereas CD4-/- animals resolved the infection, mice lacking CD8+ T cells or perforin gene succumbed to parasite challenge. The data obtained in these studies suggest that E. cuniculi infection induces a strong and early CD8+ T response that is important for host protection. The CD8+ T cell-mediated protection depends upon the CTL activity of this cell subset, as the host is rendered susceptible to infection in the absence of this function. This is the first report in which a strong dependence upon the cytolytic activity of host CD8+ T cells has been shown to be important in a parasite infection.

Animals↗