Search PubMed⌕ Search

Biomedical subjects

M Petersson

Publications and source records attributed to M Petersson.

At least 37 records · Page 2Linked to original sources
PubMed1998

Sample enrichment in a single levitated droplet for capillary electrophoresis.

This paper describes sample enrichment in a single levitated droplet for capillary electrophoresis (CE) analysis. The droplet was trapped in an acoustical field. The minute sample volumes needed for the enrichment procedure were precisely handled using a piezoelectric flow-through liquid microdispenser. Droplets with a volume of 65 pl were ejected from the device at a repetition rate ranging from one single droplet up to several hundreds per second. By counting the number of droplets ejected and accumulated in the levitated drop the sample volume was controlled. Through solvent evaporation the analytes were enriched in the diminishing droplet. The droplet was then injected into a CE capillary and the analytes, dansyl-Gly and dansyl-Val dissolved in ethanol, were separated in a 100 mM borate buffer (pH 9.0) utilising UV-absorption detection at 200 nm near the capillary outlet. Enrichment of 36000 sample droplets (2.3 microl) through solvent evaporation in the levitated drop resulted in a concentration limit of detection (CLOD) of 15 nM for the dansylated amino acids as compared to a CLOD of 2.5 microM which was achieved using standard hydrodynamic injection without preconcentration.

Electrophoresis, Capillary↗
PubMed1998

Immunization with a lymphocytic choriomeningitis virus peptide mixed with heat shock protein 70 results in protective antiviral immunity and specific cytotoxic T lymphocytes.

Heat shock proteins (hsp's) isolated from murine cancer cells can elicit protective immunity and specific cytotoxic T lymphocytes (CTLs) by channeling tumor-derived peptides bound to hsp's to the major histocompatibility class I antigen presentation pathway. Here we have investigated if hsp70 can be used in a novel peptide vaccine for the induction of protective antiviral immunity and memory CTLs. A CTL epitope from the well-defined lymphocytic choriomeningitis virus (LCMV) system was mixed with recombinant hsp70 in vitro under conditions that optimize peptide binding to hsp70. Mice were immunized with the hsp70-peptide mixture and challenged with LCMV. Virus titers were reduced 10-100-fold in these mice compared to control mice. Immunization with the hsp70-peptide mixture resulted in the development of CTL memory cells that could be reactivated during LCMV infection, and that in a 51Cr-release assay could lyse cells pulsed with the same peptide, but not cells pulsed with another LCMV peptide. These results show that hsp70 can be used with CTL epitopes to induce efficient protective antiviral immunity and the generation of peptide-specific CTLs. The results also demonstrate the usefulness of hsp70 as an alternative to adjuvants and DNA vectors for the delivery of CTL epitopes to antigen-presenting cells.

Adjuvants, Immunologic↗
PubMed1998

Oxytocin increases the survival of musculocutaneous flaps.

The aim of the present study was to evaluate the effect of oxytocin on survival of musculocutaneous flaps in male Sprague-Dawley rats. For this purpose oxytocin (0.1 or 1.0 mg/kg), an oxytocin antagonist (1-deamino-2-D-Tyr-(OEt)-4-Thr-8-Orn-oxytocin) (1.0 mg/kg) alone or in combination with oxytocin (1.0 mg/kg) or saline was given subcutaneously (s.c.), 24 hours and 1 hour before and 24 hours after flap surgery. In addition, oxytocin (1 microg/kg) or saline was given intracerebroventricularly (i.c.v.) according to the same schedule. Six days after surgery the amount of viable tissue was measured. Oxytocin 1.0 (but not 0.1) mg/kg s.c. and 1.0 microg/kg i.c.v. increased survival of the flaps (s.c.: 13.8+/-14.6% versus 6.10+/-5.45%; p<0.05 and i.c.v.: 25.5+/-14.0% versus 10.3+/-5.79%; p<0.01). This effect was abolished by the oxytocin antagonist. Furthermore, the oxytocin-treated rats had significantly higher plasma levels of insulin-like growth factor-1 (IGF-1) (p<0.05). These data indicate that oxytocin increases the survival of musculocutaneous flaps. The effect seems to be exerted within the central nervous system since a 1000 fold lower dose of oxytocin given i.c.v. increased flap survival to the same extent as the s.c. given dose. IGF-1 might be one of the mediators of this effect.

Animals↗
PubMed1998

Steroid dependent effects of oxytocin on spontaneous motor activity in female rats.

In the present study, dose relationships for effects of oxytocin (OXY) on spontaneous motor activity in female rats were investigated. Ovariectomized (OVX) and cycling female Sprague-Dawley rats were given OXY 10-1000 microg/kg s.c. or saline, 10 min before registration of motor activity in an open-field arena. In the OVX rats, 100 microg/kg of OXY increased the activity in the center of the arena, whereas 1000 microg/kg decreased locomotor activity (LA). In the cycling rats, OXY 100-1000 microg/kg decreased LA during diestrus, while 1000 microg/kg also decreased LA during metestrus. The latter dose also reduced the exploratory behavior during estrus. In a second experiment, OVX rats were pretreated with estradiol benzoate (EB) and progesterone (P). When P levels were predominant, OXY 10-1000 microg/kg decreased LA. Oxytocin 10-100 microg/kg given after pretreatment with EB increased the activity in the center of the arena, whereas 1000 micro/kg given in the presence of both EB and P increased peripheral activity (PA). These results show that the effects of OXY on motor activity in female rats are modified by female sex steroid hormones.

Analysis of Variance↗
PubMed1998

Decreased expression of signal-transducing CD3 zeta chains in T cells from the joints and peripheral blood of rheumatoid arthritis patients.

Although T cells from patients with rheumatoid arthritis (RA) have previously been determined to have poor proliferative responses to a variety of stimuli, the underlying mechanism is not known. We have investigated the expression of the signal-transducing zeta molecule in subsets of T cells and natural killer (NK) cells derived from the peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cells (SFMC) of RA patients using quantitative flow cytometry, Western blot analysis and immunohistochemistry. A decrease of zeta expression was apparent in all investigated lymphocyte subsets from the PBMC and SFMC of RA patients, as compared to the corresponding subsets from healthy age- and sex-matched controls. A less pronounced reduction of cell surface-located CD3 epsilon, CD4 and CD8 was also located in T cells from SFMC as compared to PBMC from RA patients. Biochemical demonstration of the low or absent CD3 zeta in PBMC from patients with RA was achieved by Western blot analysis. Immunohistochemical staining and image analysis also confirmed the low expression of zeta chains in synovial tissue of RA patients. The possibility that the decreased expression of zeta and of immune functions of T cells from RA patients may be related to the presence of free oxygen radicals, as we have previously reported in cancer patients, should be considered.

Arthritis, Rheumatoid↗
PubMed1998

PBLs of early breast carcinoma patients with a high nuclear grade tumor unlike PBLs of cervical carcinoma patients do not show a decreased TCR zeta expression but are functionally impaired.

Peripheral blood lymphocytes (PBLs) of patients with cervical intraepithelial neoplasia (CIN), cervical carcinoma, or early breast carcinoma were tested for the expression of T cell receptor zeta chain (TCR zeta) and CD16 zeta chain and production of interferon-gamma (IFN gamma) and interleukin (IL) 10. We found that in all patients with CIN and invasive cervical carcinoma, PBLs showed a reduced TCR zeta and CD16 zeta expression and a significant down-regulation in IFN gamma production (a T helper 1 cytokine) after anti-CD3 stimulation. However, the IL 10 secretion (a T helper 2 cytokine) was not diminished after anti-CD3 stimulation. This indicates that only T helper 1 cells are affected by the down-regulation of the TCR zeta chain expression. We also analyzed PBLs of 12 patients with early breast carcinoma. In these patients, we found TCR zeta and CD16 zeta expression down-regulation in 2 of 12 patients. Six of 12 patients had an enhanced TCR zeta expression. The enhanced TCR zeta expression correlated with a reduced IFN gamma expression after anti-CD3 stimulation. These data show that in general PBLs of early breast carcinoma patients, unlike those of cervical carcinoma patients, do not show a decreased TCR zeta expression. However, a functional impairment of T cells was observed in the subgroup of early breast carcinoma patients with a high nuclear grade of their tumor.

Breast Neoplasms↗
PubMed1998

Postnatal oxytocin injections cause sustained weight gain and increased nociceptive thresholds in male and female rats.

The aim of the present study was to investigate possible long-term effects of postnatally administered oxytocin on weight gain, gastrointestinal hormone levels, and nociceptive thresholds in rats. For this purpose, s.c. daily injections of oxytocin (1 mg/kg) or saline (NaCl, 0.9%) were given to male and female rat pups on d 10-14 after birth. The animals were killed at the age of 60 or 94 d. Treatment with oxytocin resulted in higher body weight in males, 60 d after birth, and in females from d 60 and throughout the rest of the experiment, compared with controls. The higher body weight was due to an increased weight gain in oxytocin-treated rats, compared with controls, which was most pronounced between 40 and 60 d after birth. Oxytocin-treated male rats had increased circulating levels of cholecystokinin, a tendency to increased plasma levels of insulin (p = 0.066), and relatively more adipose tissue in the thigh and interscapular region, compared with controls. At the age of 60 d, oxytocin-treated female and male rats had a prolonged withdrawal latency when measured in the tail-flick test, compared with controls. This study shows that oxytocin can induce long-lasting changes in weight gain, hormone levels, and nociceptive thresholds, when administered postnatally, in female and male rats.

Adipose Tissue↗
PubMed1997

Generation of CD8+ T cells specific for transporter associated with antigen processing deficient cells.

Cells with impaired transporter associated with antigen processing (TAP) function express low levels of cell surface major histocompatibility complex (MHC) class I molecules, and are generally resistant to lysis by MHC class I restricted cytotoxic T lymphocytes (CTLs). Here we report the generation of MHC class I restricted CD8(+) CTLs that surprisingly require target cell TAP deficiency for efficient recognition. C57BL/6 (B6) mice immunized with syngenic B7-1 (CD80) expressing TAP-deficient cells generated a potent CTL response against both TAP-deficient RMA-S tumor cells and TAP-deficient Con A blasts, whereas the corresponding TAP-expressing target cells were considerably less susceptible or resistant to lysis. The CTL epitopes recognized were expressed also by the human TAP-deficient cell line T2, transfected with appropriate MHC class I molecules. B6 mice immunized with B7-1-transfected TAP-deficient RMA-S cells were protected from outgrowth of a subsequent RMA-S tumor challenge. These findings are discussed in relation to the biochemical nature of MHC class I dependent CTL epitopes associated with impaired TAP function, as well as implications for immunotherapy and autoimmunity.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Down-regulation of the expression and function of the transporter associated with antigen processing in murine tumor cell lines expressing IL-10.

The MHC class I molecules present antigenic peptides to CTL. The peptides are delivered to the secretory pathway by TAP, which is formed by the association of MHC-encoded TAP1 and TAP2 gene products. Tumor cells incubated or transfected with IL-10 had decreased but peptide-inducible expression of MHC class I, decreased sensitivity to MHC class I-restricted CTL, and increased NK sensitivity. We here demonstrate that IL-10 expression in the murine lymphoma RMA inhibits the TAP-dependent translocation of peptides to the endoplasmic reticulum, resulting in accumulation of immature MHC class I molecules in the endoplasmic reticulum and subsequently low expression of cell surface MHC class I molecules. This finding is explained by a down-regulation of expression of TAP1 and TAP2, observed in IL-10-transfected RMA cells as well as in IL-10-transfected P815 mastocytoma cells. In the J558L plasmacytoma cell line, constitutively expressing high levels of IL-10, increased TAP-dependent translocation of peptides and expression of cell surface MHC class I could be induced by IL-10 antisense expression. IL-10 is the first example to demonstrate that a cytokine can decrease the expression and function of the TAP1/2 molecular complex and, in more general terms, the first example of a cytokine with an inhibitory effect on MHC class I-mediated Ag presentation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Synthetic peptides derived from the melanocyte-stimulating hormone receptor MC1R can stimulate HLA-A2-restricted cytotoxic T lymphocytes that recognize naturally processed peptides on human melanoma cells.

Human melanoma-specific HLA-A2 restricted CTLs have recently been shown to recognize antigens expressed by melanoma lines and normal melanocytes, including Melan-A/Mart-1, gp100, gp75, and tyrosinase. Herein, we define HLA-A2-restricted CTL epitopes from a recently cloned melanocortin 1 receptor (MC1R), which belongs to a new subfamily of the G-protein-coupled receptors expressed on melanomas and melanocytes. Thirty-one MC1R-derived peptides were selected on the basis of HLA-A2-specific motifs and tested for their HLA-A2 binding capacity. Of a group of 12 high or intermediate HLA-A2 binding peptides, three nonamers, MC1R244 (TILLGIFFL), MC1R283 (FLALIICNA), and MC1R291 (AIIDPLIYA), were found to induce peptide-specific CTLs from peripheral blood mononuclear cells of healthy HLA-A2+ donors after repeated in vitro stimulation with peptide-pulsed antigen-presenting cells. The CTLs raised against these three HLA-A2+-restricted peptides could recognize naturally processed peptides from HLA-A2+ melanomas and from Cos7 cells cotransfected with MC1R and HLA-A2. CTLs induced by the MC1R291 peptide (but not induced or induced only to a very low extent by the other two MCR1 peptide epitopes) showed cross-reactions with two other members of the melanocortin receptor family, which are more broadly expressed on other tissues. Taken together, our findings have implications in relation both to autoimmunity and immunotherapy of malignant melanomas.

Animals↗
PubMed1997

Oxytocin decreases blood pressure in male but not in female spontaneously hypertensive rats.

The aim of the present study was to investigate the effects of repeated injections of oxytocin on blood pressure and heart rate in spontaneously hypertensive rats (SHR). For this purpose subcutaneous (s.c.) injections of oxytocin 1 mg/kg or saline were given for 5 days to male and female SHR. Blood pressure and heart rate were measured daily before, during and after the oxytocin treatment period. In male rats, a significant decrease in blood pressure (systolic; p < 0.01, diastolic; p < 0.05), but no effect on heart rate, was seen the day after the first injection of oxytocin, when compared to saline-treated controls. Blood pressure decreased further in response to each injection and a maximal difference of 21 mmHg (systolic) (p < 0.01), compared to controls, was reached after the last injection. The significant effect was gone 3 days after the last injection, although a tendency to a lower blood pressure in the oxytocin-treated rats persisted. On day 10, the oxytocin-treated SHR males again had a significantly lower systolic blood pressure (p < 0.05). In female SHR, the same treatment with oxytocin affected neither blood pressure nor heart rate. These results show that oxytocin may cause a sustained decrease in blood pressure, without affecting heart rate, in male but not in female SHR.

Animals↗
PubMed1997

Mechanisms of escape from CD8+ T-cell clones specific for the HER-2/neu proto-oncogene expressed in ovarian carcinomas: related and unrelated to decreased MHC class 1 expression.

We have developed an in vitro model to study mechanisms by which ovarian tumor cells that over-express the HER-2/neu proto-oncogene escape recognition by TCD8+. Nine tumor-specific, HLA A2-restricted TCD8+ clones were isolated from 2 ovarian tumor-specific TCD8+ lines derived from tumor-infiltrating or -associated lymphocytes. Of these, 2 clones recognized the previously defined HER-2/neu epitope E75 (a.a. 369-377) and one recognized the C85 epitope (a.a. 971-979), whereas the specificity of the remaining 6 clones was unknown. Three different tumor escape variants (EVC8, EVC22 and EVC36) were produced by co-culturing an ovarian tumor line over-expressing HER-2/neu with these autologous TCD8+ clones. Cell surface expression of HLA A2 was markedly decreased on all 3 escape variants, relative to the parental tumor line, while no significant decrease in their expression of the HER-2/neu, ICAM-1 or LFA-3 molecules was found. There was a correlation between the level of tumor-specific recognition and HLA A2 expression among the tumor clones isolated from 2 of the escape variants (EVC8 and EVC36). In contrast, high HLA A2-expressing tumor clones isolated from the EVC22 variant, or EVC22 which had regained high HLA A2 expression through IFN-gamma treatment, were not recognized by the HER-2/neu-specific TCD8+ clone C-22. No mutations were found in the cDNA or the genomic DNA derived from the PCR product corresponding to a 496 bp fragment including the region coding for the E75 epitope of the HER2/neu gene in the EVC22 variant. Collectively, this in vitro model underlines the importance of decreased expression of the HLA restriction element for escape from tumor-specific TCD8+ but also demonstrates that additional mechanisms exist.

Down-Regulation↗
PubMed1997

Three approaches to enantiomer separation of beta-adrenergic antagonists by capillary electrochromatography.

Three different capillary electrochromatographic methods for the enantiomer separation of beta-adrenergic antagonists (acebutolol, alprenolol, atenolol, metoprolol, pindolol, prenalterol, and propranolol) were applied using different cyclodextrins (beta-cyclodextrin, carboxymethyl-beta-cyclodextrin and dimethyl-beta-cyclodextrin) added to the electrolyte, a cross-linked protein-gel (cellobiohydrolase I) and a molecularly imprinted ((R)-enantiomer of propranolol) superporous polymer as chiral selectors. Through use of these different separation strategies, all the beta-adrenergic antagonists studied could be resolved into their enantiomers, although the three methods were carried out without extensive optimization. The protein and molecularly imprinted phases gave the highest selectivities whereas employing cyclodextrins resulted in the highest separation efficiency. Proteins and cyclodextrins are primarily natural products, albeit the cyclodextrins can be derivatized. In contrast, the molecularly imprinted chiral stationary phase can be highly customized when produced.

Adrenergic beta-Antagonists↗
PubMed1997

Efficient harvest of in vivo IL-2-activated CD3+ lymphocytes for adoptive immunotherapy by selective leukapheresis (lymphocytapheresis).

Autologous activated lymphocytes are an alternative to tumor-infiltrating lymphocytes for adoptive immunotherapy. We developed a method of selective lymphocytapheresis that harvests large numbers of interleukin-2 (IL-2)-activated autologous T lymphocytes. Five patients with metastatic malignant melanoma received 2.4 x 10(6) IU/m2 IL-2 sc. once a day 5 days a week for 3 weeks before lymphocytapheresis. Four patients went through lymphocytapheresis without IL-2 pretreatment. After IL-2 pretreatment, activated memory T cells increased significantly. Increasing CD3+ cells paralleled the significant enhancement of the cytotoxic activity against an HLA-A2-matched allogeneic melanoma cell line during the 3 weeks of IL-2 pretreatment. Lymphocytapheresis was performed 72 h after the last IL-2 injection to obtain the maximum recovery of activated lymphocytes at the peak of the rebound phenomenon. IL-2 pretreatment resulted in many more lymphocytes in the harvest than without pretreatment. The percentage, number, and lytic units of CD3+ cells harvested by the differential apheresis were significantly higher than were present in peripheral blood before lymphocytapheresis. These results show that pretreatment of melanoma patients with low-dose IL-2 before lymphocytapheresis allows the selective harvest of large numbers of activated T lymphocytes for adoptive immunotherapy.

Adult↗
PubMed1997

2-year clinical performance of a fluoride-containing fissure sealant in young schoolchildren at caries risk.

PURPOSE: To evaluate the clinical performance of Helioseal-F, a fluoride-containing fissure sealant, in school children at caries risk. MATERIALS AND METHODS: A caries risk assessment based on past caries experience, saliva microbial tests, buffer capacity and frequency of sugar intake was carried out in 204 healthy children, 6-7 years of age. Children exhibiting one or more risk factors were considered at caries risk (n = 121) and their permanent molars were sealed with a fluoride-containing fissure sealant, thus forming a fissure sealant group (FSG). The remaining 83 children with low caries risk received no fissure sealants and constituted a reference group (RG). Both groups were followed for 2 years. From 15 children of both groups, unstimulated whole saliva was collected 1 month after sealant placement in order to determine fluoride levels. In another 20 children, a split-mouth study design was utilized to compare the colonization of mutans streptococci adjacent to and on F-containing sealants and conventional controls. The sealants were placed by dental hygienists according to the manufacturers' instructions. RESULTS: A total of 431 fissure sealants were placed at baseline. Complete retention was found in 76.6% during the study period while 22.0% were partially lost. Six sealants (1.4%) were completely lost. The enamel caries incidence was 45% lower (P < 0.05) in the permanent molars of the caries risk FSG compared with the low risk RG. There was no significant increase in saliva fluoride concentration following placement of the sealants and the proportion of mutans streptococci in relation to total viable counts was unaffected by type of material. The levels of salivary mutans streptococci were mainly unchanged in both groups during the study period, while the levels of salivary lactobacilli decreased in the FSG.

Analysis of Variance↗
PubMed1996

Oxytocin increases nociceptive thresholds in a long-term perspective in female and male rats.

Oxytocin (0.1 and 1.0 mg/kg s.c.) given to male rats during 5 days, increased tail-flick latency when measured 1 (P < 0.05) and 7 days (0.1 mg/kg, P < 0.05; 1.0 mg/kg, P < 0.01) after the last injection. The effect was gone 2 weeks after the end of the treatment. If an additional injection of oxytocin was given 10 days after a previous 5 day treatment period, the significant difference persisted after 3 weeks (P < 0.05). Tail-flick latency was significantly delayed also in oxytocin-treated females when measured 1 week after the treatment period (P < 0.05). Naloxone, but not an oxytocin antagonist, temporarily antagonised the oxytocin induced delay in withdrawal latency. This indicates that oxytocin may act by increasing the activity of opioid mechanisms.

Animals↗
PubMed1996

Hydrogen peroxide secreted by tumor-derived macrophages down-modulates signal-transducing zeta molecules and inhibits tumor-specific T cell-and natural killer cell-mediated cytotoxicity.

Although alterations in CD3-associated signal-transducing molecules in tumor-infiltrating T cells of patients with advanced cancer have been previously described, the mechanism behind these changes is not known. We demonstrate that macrophages isolated from metastatic lymph nodes of patients with malignant melanoma down-regulate levels of CD3 zeta in autologous peripheral blood T cells. Lipopolysaccharide (LPS)- or phorbol 12-myristate 13-acetate (PMA)-stimulated monocytes derived from peripheral blood of healthy donors also induced decreased expression of CD3 and CD16-associated zeta chains similar to that observed in T cells and natural killer (NK) cells of patients with advanced cancer. Co-culture with activated monocytes impaired Ca2+ mobilization in peripheral blood derived-T cells when stimulated with monoclonal antibodies to CD3 and also strongly inhibited melanoma-specific cytotoxic T lymphocyte (CTL) activity and NK activity. The presence of catalase, a scavenger of H2O2, during co-culture almost totally abrogated the inhibitory effect of activated monocytes on melanoma-specific CTL lines and on NK cells. Pre-treatment of CTL or NK cells with nontoxic concentrations (1 x 10(-5) M) of H2O2 also severely reduced their cytotoxic activity which could be prevented by catalase. The decrease in CD3 zeta and in CD16 zeta expression, induced by macrophages isolated from metastatic lymph nodes or by LPS-stimulated monocytes, was also prevented by catalase when maintained throughout the co-culture period. The possibility that monocyte/macrophage-derived reactive oxygen metabolites contribute directly to alterations in signal transducing molecules of T cells and NK cells and to the mechanism of immunosuppression in individuals with cancer should be considered.

CD3 Complex↗