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L Rapp

Publications and source records attributed to L Rapp.

12 recordsLinked to original sources
PubMed2006

Effect of DSS-induced colitis on visceral sensitivity to colorectal distension in mice.

The present study aimed at evaluating the effect of dextran sodium sulphate (DSS)-induced colitis on visceral sensitivity, measured as the visceromotor response (VMR) to colorectal distension (CRD) in BALB/c and C57Bl/6 male mice. Inflammation was induced by the addition of 4% DSS to the drinking water for 5 (C57Bl/6) or 6-7 days (BALB/c). Parallel groups were used to monitor histopathological changes and visceral sensitivity. Pseudo-affective visceral pain responses were evoked using an increasing phasic CRD paradigm (10-60 mmHg) in conscious mice on predetermined days (pretreatment controls, 12, 16, 20, 30, 40 and 51). In both mouse strains, significant histopathological changes developed between days 2 and 5 of DSS treatment, and persisted until day 12 (P < 0.05). On day 15, inflammatory scores were reduced by about 50%. Despite evidence of inflammation in DSS-treated mice, no differences could be shown in the VMR to CRD between DSS-treated mice and controls at any time point tested. In addition, no differences were seen before and after DSS treatment in the same group of mice. In conclusion, these data suggest that DSS-induced colonic inflammation does not affect the visceral sensitivity to CRD, neither at short or long term, in BALB/c or C57Bl/6 male mice.

Animals↗
PubMed1999

The bovine papillomavirus type 1 E6 oncoprotein sensitizes cells to tumor necrosis factor alpha-induced apoptosis.

Expression of viral proteins may result in susceptibility of cells to the cytotoxic effect of Tumor Necrosis Factor Alpha (TNF). While murine C127 cells containing the bovine papillomavirus type 1 (BPV-1) genome were reported to exhibit increased TNF sensitivity, the gene(s) responsible was not identified. The BPV-1 E6 oncoprotein induces tumorigenic transformation of murine C127 cells and stimulates transcription when targeted to a promoter. BPV-1 E6 was introduced into C127 cells (PBE6) by retroviral infection and stable clones were isolated. These cells showed increased apoptosis in response to TNF, as measured by several criteria. TNF-induced apoptosis in PBE6 cells was accompanied by increased release of arachidonic acid, indicating that phospholipase A2 was activated. We also provide evidence that BPV-1 E6 mediated-sensitization of cells to TNF-induced apoptosis can occur in the absence of p53.

Animals↗
PubMed1998

The papillomavirus E6 proteins.

Specific types of human papillomaviruses (HPV) are strongly associated with the development of cervical cancer. The E6 gene from cancer-related HPVs has exhibited functions in tumorigenesis, regulation of transcription, telomerase, and apoptosis. Cancer-related HPVs E6 proteins bind the tumor suppressor p53 and promotes its degradation through an ubiquitin-dependent pathway. Several additional cellular E6-binding proteins have recently been identified and implicated in playing roles in p53-independent functions of E6.

Apoptosis↗
PubMed1996

Initiation of impaired outer segment degradation in vivo using an antisense oligonucleotide.

This paper describes the first successful in vivo application of antisense DNA technology to induce the accumulation of photoreceptor outer segment derived debris in the retina. An antisense oligonucleotide (CatSC), which was previously demonstrated to be an effective tool to induce debris accumulation in vitro, was injected into the vitreous of pigmented and non-pigmented rats. The animals were euthanased 7 days after the injections. The number of inclusions significantly increased in the RPE layer of Long Evans and RCS-rdy + rats injected with 66 ug of CatSC to 96.2 +/- 13.6 (SD) (p < 0.0003) and 204.2 +/- 39.3 (SD) (p < 0.0001), respectively. The difference between the number of phagosome-like inclusions present in control saline, 6.6 ug of CatSC or 66 ug of sense oligonucleotide (S1) injected animals was not statistically significant. There were no abnormalities observed in the inner layers of the retina but the accumulation of phagosome-like inclusions was accompanied by disorganisation in the apices of outer segments. The large number of inclusions found in CatSC treated animals showed the characteristics of phagosomes containing stacks of undigested photoreceptor outer segment membranes which suggest that the lysosomal digestion process was halted or at least slowed down by the antisense oligonucleotide.

Animals↗
PubMed1995

Stable expression and functional characterization of a human cardiac Na+ channel gene in mammalian cells.

In order to develop mammalian cell lines expressing a functional human heart Na+ channel gene (hH1), Chinese hamster ovary (CHO-K1) cells and HeLa cells were transfected with the hH1 gene and the bacterial neomycin (neo) resistance gene. In CHO-K1 cells, direct screening for hH1-positive, G418-resistant colonies by functional patch clamp analysis was complicated due to low-level endogenous expression of a brain-type Na+ channel. Therefore, we developed a stepwise strategy for isolation of cell lines expressing functional hH1 Na+ channels: G418-resistant colonies were sequentially analysed for (1) chromosomal integration of hH1 DNA by PCR, (2) specific hH1 mRNA expression by RT-PCR, (3) hH1 protein production by immunoprecipitation with hH1-specific antisera, and (4) hH1 Na+ channel function by patch-clamp analysis. Using this strategy we obtained two CHO-K1 cell lines which express functional human heart Na+ channels. However, using the same strategy, we were unsuccessful in obtaining functional, hH1-positive HeLa cell lines, even though hH1 mRNA and protein was produced in these cells. The two CHO-K1 cell lines stably express human cardiac Na+ channels which retain normal electrophysiological characteristics with respect to activation and inactivation. In addition, the Na+ channels expressed in these cells are blocked by tetrodotoxin with an IC50 value of 2.5 microM; consistent with known cardiac Na+ channel pharmacology. The density of channels is high enough to permit recording of pseudomacroscopic currents in excised outside-out patches of membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

WIN 17317-3: novel nonpeptide antagonist of voltage-activated K+ channels in human T lymphocytes.

We report the in vitro biological characterization of WIN 17317-3 (1-benzyl-7-chloro-4-n-propylimino-1,4-dihydroquinoline hydrochloride), a novel inhibitor of voltage-activated (n-type) K+ channels in human T lymphocytes. WIN 17317-3 inhibits 125I-charybdotoxin binding to n-type K+ channels with an IC50 value of 83 +/- 4 nM. WIN 17317-3 demonstrates competitive inhibition of 125I-charybdotoxin binding by increasing its dissociation constant without changing the total number of channels bound and by having no effect on its dissociation rate constant. WIN 17317-3 inhibits whole-cell, n-type K+ currents with characteristics indicative of open channel block and has an IC50 value of 335 nM. The compound is 150-fold selective for n-type K+ channels, compared with Ca(2+)-activated, charybdotoxin-sensitive K+ channels in smooth muscle. In purified CD4+ T lymphocytes activated with either anti-CD3 plus phorbol ester or anti-CD3 plus anti-CD28, WIN 17317-3 decreases interleukin-2 production with EC50 values of 0.8 microM and 1 microM, respectively. WIN 17317-3 is a novel, potent, and selective nonpeptide n-type K+ channel antagonist that inhibits interleukin-2 production in human T lymphocytes.

Cell Line↗
PubMed1995

Phase I trial of simultaneous administration of interleukin 2 and interleukin 4 subcutaneously.

Interleukin (IL) 2 plays an important role in enhancing the immune response, whereas IL-4 has pluripotent activities which include affecting immune function. Preclinical data suggest that the combination might have enhanced immunomodulatory activity. In this Phase I trial in patients with advanced solid tumors, both IL-2 and IL-4 were given by separate s.c. injections simultaneously daily, 5 days in a row, Monday through Friday, for 3 consecutive weeks, followed by a 1-week break from treatment. Cycles could be repeated. The dose of IL-2 was kept constant at 9 x 10(6) IU/m2/injection while the dose of IL-4 was escalated beginning at 100 microgram/m2/injection and increasing by 100-microgram/m2 increments to a planned level of 400 microgram/m2/injection. Sixteen patients were entered in this study, with one patient being ineligible because of the presence of brain metastases. Of the 15 eligible patients, there were 14 males and 1 female, with a median age of 54 (range, 38-67) years and initial performance status of 0 in 5 patients and 1 in 10 patients. Patients were treated at levels of up to 300 microgram/m2/injection of IL-4 before the study was closed due to withdrawal of the drug by the manufacturer. The most commonly observed toxicities were fatigue, fever and chills, local reaction, nausea/vomiting and anorexia, headache and nasal stuffiness, and coughing, sometimes with the production of clear white sputum, more common in smokers. Duodenal ulcers occurred in one patient and one patient had grade 4 cardiac toxicity consisting of an asymptomatic minimal elevation of the creatinine phosphokinase MB isoenzyme (CPK-MB). Grade 3 hyponatremia occurred in two patients, and elevated liver function tests and creatinine occurred but were not dose limiting. Eosinophilia of unknown significance occurred in all patients. There were statistically significant elevations in absolute numbers of most T-cell subsets examined, without changes in circulating B cells. No antibodies to the IL-4 were found after one cycle. One patient with renal cell carcinoma showed a significant decrease in tumor burden after one cycle of treatment. Because of the IL-4 withdrawal, the maximum tolerated dose for this combination of drugs given by the route and schedule used here was not determined and will require additional testing. Subcutaneous IL-2 and IL-4 given simultaneously show important immunomodulatory and antitumor effects and should be tested further in cancer patients.

Adult↗
PubMed1993

Isolation and characterization of monoclonal antibodies to a recombinant human topoisomerase II polypeptide.

We have produced two murine monoclonal antibodies (SWT3D1 and SWR1C2) to a recombinant polypeptide corresponding to the carboxyl-terminal one-third (amino acid 854-amino acid 1447) of human topoisomerase II alpha. Each antibody is able to recognize intact human topoisomerase II using immunoblotting and enzyme-linked immunosorbent assay (ELISA) techniques. Data is presented demonstrating that the antibodies bind specifically to topoisomerase II alpha but do not interact with topoisomerase II beta. The monoclonal antibodies do not recognize murine or calf thymus topoisomerase II indicating that each may bind exclusively to the human enzyme. The topoisomerase II binding sites for each monoclonal antibody have been compared in a competition ELISA. The SWT3D1 antibody had no significant effect on the binding efficiency of biotinylated SWR1C2 antibody. Although SWR1C2 was capable of inhibiting the binding of biotinylated SWT3D1, this only occurred at concentrations approximately 1000-fold higher than those required of SWT3D1 to block binding of itself. These results suggest that SWT3D1 and SWR1C2 do not recognize identical epitopes on topoisomerase II.

Animals↗
PubMed1983

Differential antigenic expression of the DBA/2 lymphoma L1210 and its sublines: cross-reactivity with C3H mammary tumors as defined by syngeneic monoclonal antibodies.

The expression of tumor-associated antigens on the DBA/2 lymphoma L1210 and three L1210 sublines, each resistant to a different antileukemic agent [guanazole, methylglyoxal-bis(guanylhydrazone), and 4,4-diacetyldiphenylurea-bis(guanylhydrazone)] was investigated by the use of monoclonal hybridoma antibodies. Hybridomas were produced by the fusion of spleen cells from DBA/2 mice immunized with irradiated L1210 or L1210 subline cells and cells of a non-immunoglobulin-secreting BALB/c myeloma variant. Three clones producing antibodies reacting with L1210 or L1210 subline cells were used to study the antigenic expression of L1210 and L1210 subline cells. Monoclonal antibodies from anti-L1210 and anti-L1210 subline hybridomas exhibited a greater reactivity with L1210 subline cells than with L1210 cells in complement-dependent cytotoxicity, quantitative absorption, and membrane immunofluorescence experiments, thereby demonstrating a tumor-associated antigen shared by L1210 and the L1210 sublines and an increased expression of this antigen on subline cells. Cross-blocking tests of antibody binding demonstrated that monoclonal antibodies from anti-L1210 and anti-L1210 subline hybridomas recognized the same or very closely situated antigenic determinants on the tumor cell surface. Most syngeneic and allogeneic tumor cells used as controls failed to react with the anti-L1210 and anti-L1210 subline hybridoma antibodies. However, two syngeneic tumors, L5178Y and P388-D1, demonstrated a significant reaction with the monoclonal antibodies. In addition, several spontaneous mammary tumors from C3H/St and DBA/2Ha, both high-frequency mammary tumor strains, reacted in various degrees with anti-L1210 or anti-L1210 subline hybridoma antibodies in absorption tests and in immunofluorescence experiments. On the other hand, liver, kidney, and spleen from normal C3H/St mice, as well as mammary tumors from BALB/c and C3Hf, both low-frequency mammary tumor strains, did not demonstrate significant reactivity in similar experiments. Normal lactating mammary glands from high-frequency mammary tumor mouse strains reacted with the monoclonal antibodies, whereas lactating mammary glands from low-frequency mammary tumor mouse strains were negative by this method. Purified murine mammary tumor virus preparations reacted strongly with the monoclonal antibodies in solid-phase radioimmunoassays, whereas a purified murine leukemia virus preparation failed to do so in similar experiments. These results indicate that the tumor-associated antigen(s), differentially expressed on L1210 and L1210 subline cells, is related to an antigen which is associated with the murine mammary tumor virus.

Animals↗
PubMedDate not supplied

Modeling surface water critical loads with PROFILE: possibilities and challenges.

The critical load concept has become a valuable tool for policymakers in the European negotiations on emission reductions. Despite the international acceptance, ongoing validation of critical load methodology is of the utmost importance to avoid a situation where the calculation results are difficult to defend. In this paper we explore the potential of using the steady state soil chemistry model PROFILE as an alternative to the Steady State Water Chemistry (SSWC) method for calculating critical loads of acidity. The hypothesis is that the uncertainty in prediction of preindustrial leaching of base cations is reduced when soil properties instead of lake chemistry are used as input data. Paleolimnological reconstructions of preindustrial lake chemistry are used to test PROFILE. As PROFILE requires soil data that are not generally available on a catchment level, we used distributions of crucial parameters from soil survey data within the vicinity of five lakes for which paleoecological pH reconstructions were available. An important concern is the characterization of catchment hydrology. A calibration of the "effective" soil depth, needed to give PROFILE predictions that coincided with paleolimnology, suggested that approximately 0.6 m of the total soil depth was hydrologically active in supplying acid neutralizing capacity (ANC) to runoff through weathering. At present, there is insufficient evidence to either recommend or reject the PROFILE model for surface water critical loads. Before such a judgement can be made, the approach presented here has to be tested for other regions, and the definition of catchment hydrology needs to be investigated further.

Acid Rain↗