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J Schmitz

Publications and source records attributed to J Schmitz.

At least 19 recordsLinked to original sources
PubMed1998

Sequential production of IL-2, IFN-gamma and IL-10 by individual staphylococcal enterotoxin B-activated T helper lymphocytes.

Upon primary activation, T helper (Th) cell populations express different cytokines transiently and with different kinetics. Stimulation of naive murine splenic Th cells with the bacterial superantigen Staphylococcus aureus enterotoxin B (SEB) in vitro results in expression of IL-2, IFN-gamma and IL-10 with fast, intermediate and slow kinetics, respectively. This first report of a functional analysis of cells separated alive according to cytokine expression shows that these cytokines are not produced by different Th cell subpopulations, but can be expressed sequentially by individual Th cells. Th cells, activated with SEB for 1 day and isolated according to expression of IL-2, using the cellular affinity matrix technology, upon continued stimulation with SEB later secrete most of the IFN-gamma and IL-10. Likewise, after 2 days of SEB culture, cells expressing IFN-gamma, separated according to specific surface-associated IFN-gamma as detected by magnetofluorescent liposomes, 1 day later secrete IL-10. Thus, individual Th1 cells can contribute to the control of their own IFN-gamma expression by sequential expression of first IL-2, supporting their proliferation, and later IL-10, down-regulating the production of IFN-gamma-inducing monokines and limiting the pro-inflammatory effects of IFN-gamma.

Animals↗
PubMed1998

Molecular phylogeny of Vespidae (Hymenoptera) and the evolution of sociality in wasps.

The oriental Stenogastrinae is a group in which there is considerable interest as regards the study of evolution of sociality in wasps, because they show broad diversity in social behavior. Using cladistic analysis on morphological and behavioral data, they have been grouped together with the social Vespinae and Polistinae in the family of Vespidae. This is not without dispute, because several other morphological and behavioral characters separate Stenogastrinae from the other Vespidae subfamilies. DNA sequences were obtained from nuclear 28S ribosomal DNA and the mitochondrial 16S ribosomal DNA of two Apis species and nine social and three solitary wasp species of the family Vespidae. Solitary wasps of the family Braconidae and Pteromalidae were used as outgroups. Parsimony, distance, and maximum-likelihood methods of both mitochondrial and nuclear DNA did not support the conventional phylogenetic position of Stenogastrinae. In all phylogenetic reconstructions, the solitary Eumeninae were a sister taxon to the Polistinae + Vespinae cluster. The analyzed sequences provide strong evidence that sociality has independently evolved twice in the Vespidae.

Animals↗
PubMed1998

Syndrome of intractable diarrhoea with persistent villous atrophy in early childhood: a clinicopathological survey of 47 cases.

BACKGROUND: The syndrome of intractable diarrhoea of infancy is heterogeneous and includes several diseases with diverse aetiologies. This study determines whether diagnostic categories can be defined on the basis of clinicopathological analysis. METHODS: European Society of Paediatric Gastroenterology, Hepatology and Nutrition members were surveyed to identify cases of intractable diarrhoea with persisting small intestinal enteropathy. A retrospective clinicopathological analysis was performed on cases showing life-threatening diarrhoea within the first 24 mo of life and requiring total parenteral nutrition, which were characterized by persistent villous atrophy, and resistance to therapy. RESULTS: Forty-seven infants were identified with intractable diarrhoea. Villous atrophy was of varying degrees with (group I, n = 24) or without (group II, n = 18) lamina propria mononuclear cell infiltration. Group I presented later, had gut autoantibodies, and a higher prevalence of protein-losing enteropathy; a subset (group Ia, n = 12) also had extraintestinal symptoms of autoimmunity associated with a later onset of larger volume diarrhoea. Group II presented early; 8 cases (group IIa) had phenotypic abnormalities and a low birth weight; the remaining 10 (group IIb) showed mild-to-moderate villous atrophy, epithelial tufting, and abnormal crypts. Group III included five patients in whom no specific features were recognised. Twenty-one (45%) died at a median age of 24 months, 20 (43%) remained dependent on parenteral (n = 16) or enteral tube (n = 4) feeding, 4 (9%) received elimination diets plus other therapies, and 2 (4%) were lost to follow-up. CONCLUSIONS: Clinicopathological analysis allowed distinct disease groups to be identified, allowing a provisional classification to be made. This straightforward approach forms a basis for future research in this exceptionally difficult paediatric condition.

Atrophy↗
PubMed1998

Retention, HIV risk, and illicit drug use during treatment: methadone dose and visit frequency.

OBJECTIVES: This study examined two major methadone treatment factors, visit frequency and methadone dose, posited to be important in reducing intravenous drug use and human immunodeficiency virus (HIV) transmission. METHODS: One hundred fifty opiate-dependent subjects randomly assigned to four groups received 50 or 80 mg of methadone and attended a clinic 2 or 5 days per week. RESULTS: Survival analysis indicated higher dropout rates for groups having five vs two visits per week (Chi2[1]=7.76). Higher proportions of opiate-positive results on urine screens were associated with lower methadone doses (F[1,91]=4.74). CONCLUSIONS: Receiving take-home doses early in treatment enhanced treatment retention. The 50-mg dose combined with five visits per week produced the worst outcome. Fewer visits enhanced retention at 50 mg, but opiate use rates were higher at this dose than they were for either 80-mg group. The HIV infection rate at entry was 9%. No subjects seroconverted during the study. Risk behaviors for acquired immunodeficiency syndrome declined over time regardless of group/dose assignment. These results have important implications for modification of regulatory and clinic policy changes.

Adult↗
PubMed1998

Immunomagnetic enrichment of disseminated epithelial tumor cells from peripheral blood by MACS.

Disseminated epithelial tumor cells have been detected in the bone marrow and blood of cancer patients by means of immunocytochemical or immunofluorescent staining of cytocentrifuge slides, multiparameter flow cytometry, and reverse transcriptase-polymerase chain reaction. However, it is hardly possible using such methods to detect tumor cells at a frequency below 10(-6). To increase the sensitivity of these detection techniques we have developed a new technology for the enrichment of disseminated epithelial tumor cells from hematopoietic cell samples by high-gradient magnetic cell sorting (MACS). Cells are permeabilized and fixed and carcinoma cells are magnetically labeled specifically with an anti-cytokeratin 8 monoclonal antibody (mAb) directly conjugated to superparamagnetic microbeads. Magnetically labeled cells are enriched on high-gradient magnetic columns. Tumor cells are detected in the enriched cell fraction by flow cytometry, fluorescence microscopy, or immunocytochemisty. In this study we demonstrated the method using a model system in which five to 5,000 cells from a breast cancer cell line were seeded into blood cell samples from a healthy donor containing 1.2 x 10(8) leukocytes. Tumor cells were 10,477+/-4242 (n=25)-fold magnetically enriched, and 57.7%+/-16.9% (n=33) of the initially seeded tumor cells were recovered. Applying the method to 20-40 mL blood samples from patients with advanced carcinomas of the breast, prostate, colon, rectum, or lung, we were able to detect between one and 6.8 x 10(4) cytokeratin-expressing tumor cells in 21 of 34 patients. This corresponds to frequencies of tumor cells between 6.8 x 10(-9) and 1.1 x 10(-3) among nucleated cells in the original sample. Enriched tumor cells were further analyzed for expression of tissue-specific and prognostic markers such as breast mucin glycoproteins, erbB2, and CD44v6 for additional characterization and to confirm their tumor origin. The technique described could become a valuable tool for the quantification and molecular characterization of metastatic carcinoma cells in hematopoietic tissue, and may ultimately prove useful in the diagnosis, prognosis, and monitoring of patients with carcinoma.

Adult↗
PubMed1997

Ritanserin in the treatment of cocaine dependence.

Sixty-five cocaine-dependent subjects were enrolled into a 10-week randomized, double-blind study to determine the safety and efficacy of the serotonin-2 receptor antagonist, ritanserin (10 mg/day), in reducing cocaine consumption and craving. All subjects also participated in a structured intensive outpatient psychosocial program. Seventy-three percent of the participants completed the treatment program and follow-up. Subjects experienced a significant reduction in craving: 66.4% and 32.5% for the placebo and ritanserin groups, respectively. These reductions in craving were not paralleled by substantial decreases in cocaine use. Self-reported cocaine use was less frequent in the placebo group; paradoxically, blood levels of its metabolite, benzoylecgonine, were also higher although insignificantly so. Generally, ritanserin was well tolerated but significantly prolonged the QTc interval on the electrocardiogram. This outpatient program is effective at maintaining cocaine-dependent individuals in treatment and reducing craving. Ritanserin (10 mg/day) is not an efficacious adjunct to psychosocial treatment for cocaine dependence.

Adult↗
PubMed1997

In situ localization of the putative movement protein (pr17) from potato leafroll luteovirus (PLRV) in infected and transgenic potato plants.

The potato leafroll virus (PLRV) 17-kDa protein (pr17), the putative movement protein for this phloem-limited luteovirus, was localized on ultrathin sections of leaves from PLRV-infected and transgenic potato plants. The transgenic plants expressed the entire viral genome from a full-length cDNA copy (PLRVfl) or only the gene encoding pr17 (ORF4) under the control of the cauliflower mosaic virus 35S promoter. Virus-infected and PLRVfl-transgenic plants developed symptoms typical of virus infection, whereas pr17-transgenic plants did not display symptoms or ultrastructural alterations. Immunogold electron microscopy using an anti-pr17-serum detected pr17 in plasmodesmata, in virus-induced vesicles, in mitochondria, and in chloroplasts of phloem cells, in PLRV-infected as well as PLRVfl-transgenic plants. In addition, in transgenic plants, pr17 was expressed in mesophyll cells (which are not infected by PLRV under natural conditions) and localized to the same sites as in phloem cells, except in plasmodesmata. In contrast, in pr17-transgenic plants the protein was never observed on organelles, but was almost exclusively associated with plasmodesmata of all leaf cell types, indicating that the targeting of pr17 to plasmodesmata is an intrinsic property of the protein. These results support the role of pr17 in PLRV movement.

Carrier Proteins↗
PubMed1997

CD45RA-expressing memory/effector Th cells committed to production of interferon-gamma lack expression of CD31.

It has been considered before that human naive and memory/effector CD4+ T-cells cannot be subdivided solely according to the differential expression of CD45 isoforms. By the lack of expression of CD31 we have identified a subset of CD4+ CD45RA+ CD31- cells which show distinct features of antigen-experienced Th1 cells. Short term stimulation of highly purified human peripheral blood CD4+ T-cells with PMA/ionomycin, followed by the cytometric analysis of intracellular cytokines, showed that a minor subpopulation of CD4+ CD45RA+ CD45RO- cells is able to produce interferon-gamma (IFN-gamma) rapidly, a characteristic of antigen-experienced Th1 cells. Whereas among CD45RA+ CD4+ T-cells both CD31+ and CD31- subsets produce interleukin-2 (IL-2) upon PMA/ionomycin stimulation, only the CD31- subpopulation is able to produce IFN-gamma. Thus, our phenotypic and functional characterization of CD45RA+ CD45RO- Th cells shows that CD45RA+ CD45RO- cells do not represent a homogeneous population of antigen-unexperienced, naive T-cells. We speculate that a certain subset of human CD4+, CD45RO+ memory T-cells reverts to expression of the CD45RA isoform, and that this subset can be identified by the lack of CD31 expression.

Animals↗
PubMed1997

In vivo expression of a full-length cDNA copy of potato leafroll virus (PLRV) in protoplasts and transgenic plants.

A full-length cDNA copy (PLRVfl) of potato leafroll virus (PLRV) was constructed and examined in vivo for its biological activities by transient expression experiments with plasmid DNA or in vitro transcribed RNA. In addition, PLRVfl cDNA was stably introduced into the genome of potato plants by Agrobacterium-mediated leaf disc transformation. Both transient and stable expression of PLRVfl resulted in the synthesis of genomic and subgenomic PLRV RNAs. Transgenic plants accumulated the 17-kDa movement protein and displayed the typical symptoms of PLRV infection. This is the first example of the constitutive expression of a phloem-limited virus in planta.

Agrobacterium tumefaciens↗
PubMed1997

Histopathology and microbiology of isolated rectal bleeding in neonates: the so-called 'ecchymotic colitis'.

Rectal bleeding in neonates is an alarming event which suggests a possible necrotizing enterocolitis (NEC) but is usually the only symptom of an unexplained colitis characterized endoscopically by ecchymotic mucosal lesions, the so-called 'ecchymotic colitis' (EC). We studied histologically and bacteriologically 18 infants (mean age: 18 days) presenting with rectal bleeding by systematic rectosigmoidoscopy and intestinal biopsies. The 18 infants were hospitalized. Prematurity was found in seven cases and an underlying condition in 14 cases (respiratory distress: six cases; infection: six cases; surgery: two cases). Histology showed a mild to moderate inflammation (10/12) of the mucosa with a prevalence of polymorphonuclear cells (8/10), frequent focal haemorrhages (11/12) and foci of pneumatosis (4/12). Numerous bacteria were seen in the mucus layer focally forming large clusters. Cultures of intestinal biopsies yielded exclusively Enterobacteriaceae species: Escherichia coli (seven cases), Klebsiella spp. (seven cases), and Enterobacter cloacae (three cases); four cases were sterile. Our study demonstrates that neonatal bleeding is associated with endoscopic and histological 'ecchymotic colitis' lesions and with a peculiar microbial flora of EBC strains. EC and necrotizing enterocolitis share similar features raising the question of the link between the two syndromes.

Biopsy↗
PubMed1997

Receptors for carbohydrate ligands including heparin on the cell surface of Leishmania and other trypanosomatids.

By employing neoglycoproteins (NGP) and glycosaminoglycans, the detection of endogenous glycoligand-binding sites has become possible. Monitoring specific binding of 11 of these sugar receptor-specific tools, 13 trypanosomatids of monogenetic genera Blastocrithidia, Crithidia, Herpetomonas, and Leptomonas and digenetic genera Endotrypanum, Leishmania, and Sauroleishmania were analysed by agglutination and fluorescence assays. NGP showed agglutination reactions only with the digenetic but not with the monogenetic species. Sensitive flow cytofluorimetric investigations revealed that the apparently different reactivity to NGP is due to a pronounced quantitative difference in expression of binding sites between mono- and digenetic flagellates. Moreover, flow cytofluorimetry was used to demonstrate the occurrence of receptor sites for heparin on the cell surfaces of all trypanosomatids. An indication for a correlation of the binding capacity for the NGP N-acetyl-beta-D-glucosamine and heparin to differences in the pathogenicity of parasites was observed for Leishmania donovani as well as Leishmania enriettii. Infective populations of these species contained a significantly higher number of cells which had bound N-acetyl-beta-D-glucosamine and heparin than noninfective (long-term in vitro-cultured) populations. The results of the present report additionally support the hypothesis that lectin-carbohydrate interactions with neutral sugar moieties and heparin or heparin-like molecules participate in the interactions between trypanosomatids and host (cells), and that the detected binding sites for carbohydrates and heparin may thus be referred to as potential virulence factors.

Acetylglucosamine↗
PubMed1997

Germinal centre CD4+ T cells are an important site of HIV replication in vivo.

OBJECTIVE: CD4+ T cells are the main target for HIV. However, the highest HIV antigen concentration in infected subjects accumulates on the cell surface of follicular dendritic cells in the germinal centres of the lymphoid tissue. Germinal centres contain a T-helper cell subset which expresses CD57 molecules. Here we analysed virus replication and viral load in CD57+CD4+ germinal centre T cells and in the CD4+ T cells found mostly outside germinal centres (CD57-CD4+). METHODS: Peripheral blood mononuclear cells and lymph-node cells were prepared, stained for CD4 and CD57 and purified by FACS. Defined cell numbers of CD4+CD57+ cells and CD4+CD57- cells were sorted directly into polymerase chain reaction (PCR) tubes by FACS, equipped with an automated cell deposition unit and analysed by PCR to detect proviral DNA. Based on Poisson distribution, the expected level of infection was calculated. Viral replication was determined by amplifying double-spliced, single-spliced, and full-length transcripts of HIV using serially diluted cDNA of the FACS-sorted cells. RESULTS: An up to 10-fold higher frequency of infected cells was found in the CD57+CD4+ germinal centre T cells compared with CD57-CD4+ T cells. Furthermore, active viral replication was detected almost exclusively in the CD57+CD4+ T cells. CONCLUSIONS: The CD57+CD4+ germinal centre T cells are one of the sites of HIV infection and replication that may play a pivotal role in the pathogenesis of HIV infection.

Base Sequence↗
PubMed1997

[Familial adenomatous polyposis and thyroid cancer].

Familial adenomatous polyposis may exhibit extracolonic tumors which include thyroid carcinoma. It has been recently suggested that thyroid carcinomas associated with familial adenomatous polyposis show distinct histologic features different from sporadic follicular or papillary thyroid carcinomas. We report a case of thyroid carcinoma in a young girl affected by familial adenomatous polyposis, whose thyroid tumor exhibited some of these features. This finding confirms the peculiar histologic phenotype of the thyroid carcinomas associated with familial adenomatous polyposis. Alterations of the APC gene responsible for familial adenomatous polyposis may play a role in the development of these thyroid cancers.

Adenomatous Polyposis Coli↗