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M Suter

Publications and source records attributed to M Suter.

At least 73 records · Page 4Linked to original sources
PubMed1999

Inhibition of dendritic cell maturation by herpes simplex virus.

Maturation of dendritic cells (DC), leading to migration and increased T cell stimulatory capacity, is essential for the initiation of immune responses. This process is triggered by a variety of stimuli, such as inflammatory cytokines, bacterial and viral products. Using a recombinant disabled infectious single cycle herpes simplex virus 1 (HSV-1) encoding green fluorescent protein, we show that the infected DC are defective in up-regulating co-stimulatory molecules, do not produce cytokines, and do not acquire responsiveness to chemokines required for migration to secondary lymphoid organs. These results reveal yet another strategy used by HSV-1 to evade the immune response, namely the inhibition of signaling pathways involved in DC maturation.

Cell Adhesion Molecules↗
PubMed1999

Determination of 129I in atmospheric samples by accelerator mass spectrometry.

A method for the radiochemical extraction of 129I from atmospheric charcoal filters and its measurement by accelerator mass spectrometry is presented. Either the 129I concentration or the 129I/127I atom ratio can be determined in the sample. With this method, air filters from Seville, in the Southwest of Spain (37.4 degrees N, 6 degrees W) have been analyzed. Sensitivities in the order of 10(4) atoms/m3 for 129I concentrations and 10(-10) for 129I/127I atom ratios are obtained. AMS measurements are performed with the 6 MV tandem accelerator at the ETH-Hönggerberg in Zurich.

Air Pollution, Radioactive↗
PubMed1999

Dendritic cells directly trigger NK cell functions: cross-talk relevant in innate anti-tumor immune responses in vivo.

Cytotoxic T lymphocytes and natural killer cells are essential effectors of anti-tumor immune responses in vivo. Dendritic cells (DC) 'prime' tumor antigen-specific cytotoxic T lymphocytes; thus, we investigated whether DC might also trigger the innate, NK cell-mediated anti-tumor immunity. In mice with MHC class I-negative tumors, adoptively transferred- or Flt3 ligand-expanded DC promoted NK cell-dependent anti-tumor effects. In vitro studies demonstrated a cell-to-cell contact between DC and resting NK cells that resulted in a substantial increase in both NK cell cytolytic activity and IFN-gamma production. Thus, DC are involved in the interaction between innate and adaptive immune responses.

Adoptive Transfer↗
PubMed1999

Light regulation of assimilatory sulphate reduction in Arabidopsis thaliana.

Adenosine 5'-phosphosulphate reductase (APR) is considered to be a key enzyme of sulphate assimilation in higher plants. We analysed the diurnal fluctuations of total APR activity and protein accumulation together with the mRNA levels of three APR isoforms of Arabidopsis thaliana. The APR activity reached maximum values 4 h after light onset in both shoots and roots; the minimum activity was detected at the beginning of the night. During prolonged light, the activity remained stable and low in shoots, but followed the normal rhythm in roots. On the other hand, the activity decreased rapidly to undetectable levels within 24 h of prolonged darkness both in shoots and roots. Subsequent re-illumination restored the activity to 50% in shoots and to 20% in roots within 8 h. The mRNA levels of all three APR isoforms showed a diurnal rhythm, with a maximum at 2 h after light onset. The variation of APR2 mRNA was more prominent compared to APR1 and APR3. 35SO42- feeding experiments showed that the incorporation of 35S into reduced sulphur compounds in vivo was significantly higher in light than in the dark. A strong increase of mRNA and protein accumulation as well as enzyme activity during the last 4 h of the dark period was observed, implying that light was not the only factor involved in APR regulation. Indeed, addition of 0.5% sucrose to the nutrient solution after 38 h of darkness led to a sevenfold increase of root APR activity over 6 h. We therefore conclude that changes in sugar concentrations are also involved in APR regulation.

Arabidopsis↗
PubMed1999

Mast cell density and subtypes in the skin of Shar Pei dogs with cutaneous mucinosis.

Skin biopsies from 13 Shar Peis showing signs of cutaneous mucinosis and 13 control dogs of different breeds with no clinical or histological evidence of skin disease were examined. One section of each tissue sample was stained with haematoxylin and eosin, and another with toluidine blue to demonstrate the sulphated acid glycosaminoglycans in mast cell (MC) granules. To investigate the MC subtypes involved, the tryptase and chymase content of mast cells was evaluated by a double enzyme-immunohistochemical staining technique. Regardless of the staining technique, a significantly lower mast cell density in the skin of Shar Peis was demonstrated. In the dermis of control dogs, we detected a median mast cell density of 31.2 MC/mm2 using the toluidine blue staining method and 27.5 MC/mm2 using the double labelling technique. In Shar Peis only 9.1 MC/mm2 were found by toluidine blue staining (P = 0.001) and 14.8 MC/mm2 by the double labelling method (P = 0.0387). The percentile distribution of mast cell subtypes was also significantly different in Shar Peis as compared to control dogs. Whereas in the dermis of control dogs the predominant mast cell subtype was the tryptase and chymase containing MC (TC-MC) (60.4%), in Shar Pei skin the only chymase containing MC (C-MC) predominated (62.2%) and the percentage of TC-MC was significantly lower (32.9%; P = 0.0016). The percentage of only tryptase containing MC (T-MC) (4.7%) was higher in Shar Peis compared to control dogs (1.9% P = 0.0178). The data obtained indicate a possible involvement of mast cell subtypes in the pathogenesis of cutaneous mucinosis. Further investigations on the pathophysiological role of mast cell subtypes may foster understanding of the pathogenesis of cutaneous mucinosis.

Animals↗
PubMed1999

Immortalized cell lines derived from mice lacking both type I and type II IFN receptors unify some functions of immature and mature dendritic cells.

Cells with dendritic morphology obtained from several organs of mice lacking both type I and II IFN receptors were immortalized by a retrovirus and analysed for their phenotype and for their function to induce cognate immune responses in vitro and in vivo. Two cell lines called AG101 (skin) and AG116 (brain) were cloned and analysed in more detail. They constitutively expressed the cell surface markers CD45, CD11b, MHC class II, F4/80, N418, B7-2 and ICAM1 but were CD8- and B220-negative. Cells from both lines were capable of taking up ovalbumin (OVA). The processed protein was presented to the OVA-specific T cell hybridoma BO97.105 which responded specifically with the production of IL-2. AG101 and AG116 cells were able to induce a mixed lymphocyte reaction as shown by a 50-fold increase of IL-2 production over background. Naive T cells were stimulated by antigen-primed AG101 and AG116, resulting in a T cell proliferation which was 20-30 times over background, and in IL-2 production it was 10 times the background. The capacity of AG101 or AG116 cells to prime naive T cells was directly compared with freshly isolated and cultured cutaneous dendritic cells (DC) from 129 Sv/Ev mice (wtDC). After cognate T cell interaction, IL-6 (20-100-fold) and IL-12 p40 (100-1000-fold) were similarly up-regulated in either AG101, AG116 or mature wtDC. To analyse the capacity of the immortalized DC to induce antibodies in vivo, cell line AG116 was permanently infected with Borna disease virus (BDV) which is unable to replicate in adult mice. One hundred and twenty-nine Sv/Ev mice injected with different cell numbers of AG116 carrying BDV (but not control cells) produced antibodies against the viral BDVp40 and BDVp24 protein. Therefore, the cell lines AG101 and AG116 appear to unify some functions of immature and mature DC. They are able to pick up antigen and process it. In the absence of externally added cytokines, the antigen presented on AG101 or AG116 cells drives T cells with an efficiency similar to mature DC. The cloned cell lines may prove to be useful to study both immune response and replication of infectious agents in the absence of functional interferon receptors.

Animals↗
PubMed1999

Mast cell density and subtypes in the skin of dogs with atopic dermatitis.

Skin biopsies from seven dogs with atopic dermatitis and 13 dogs with no clinical or histological evidence of skin diseases were examined. The study of the atopic dogs included 11 biopsy samples of nonlesional skin and 15 samples of lesional skin. One section of each tissue sample was stained with haematoxylin and eosin and another with toluidine blue to demonstrate the sulphated acid glycosaminoglycans in mast cell (MC) granules. To investigate MC subtypes, the MC-specific proteases tryptase and chymase were examined by a double enzyme-immunohistochemical staining technique. With the double labelling technique a significantly lower mast cell density was demonstrated in lesional (P = 0.0023) and nonlesional (P = 0.0004) skin samples of the atopic dogs than in the skin of control dogs. In the dermis of control dogs, a median mast cell density of 31.2 MC/mm2 was detected with the toluidine blue staining method and of 27.5 MC/mm2 with the double labelling technique. In lesional dermis of atopic dogs 29.8 MC/mm2 were seen with toluidine blue while only 12.4 MC/mm2 were stained with the double labelling method (P = 0.0027). A similar difference was observed in nonlesional dermis samples, in which a mast cell density of 23.3 MC/mm2 was detected with toluidine blue but only 6.4 MC/mm2 with the double labelling method (P = 0.0127). The data provide evidence that mast cell granule heterogeneity exists in the dog and suggests that degranulation occurs selectively, depending on the pathological condition of the canine skin. Further investigations on the pathophysiological role of mast cell subtypes may help to elucidate the pathogenesis of atopic dermatitis.

Animals↗
PubMed1999

In-vitro susceptibility of 1982 respiratory tract pathogens and 1921 urinary tract pathogens against 19 antimicrobial agents: a Canadian multicentre study. Canadian Antimicrobial Study Group.

A total of 3903 pathogens from 48 Canadian medical centres were tested against 19 antimicrobial agents. Five agents showed activity against > or = 90% of all 1982 respiratory tract pathogens tested (ciprofloxacin, 90%; cefoperazone, 91%; ticarcillin/clavulanate, 92%; ceftazidime and imipenem, 93% each). Nine agents had > or = 90% activity against Enterobacteriaceae from respiratory tract infection (cefotaxime and ticarcillin/clavulanate, 90% each; aztreonam, ceftizoxime and ceftriaxone, 91% each; ceftazidime, 93%; ciprofloxacin, 97%; imipenem and netilmicin, 98% each). Similarly, five agents had activity against > or = 90% of all 1921 urinary tract pathogens tested (ciprofloxacin and ticarcillin/clavulanate, 90% each; cefoperazone and netilmicin, 91% each; imipenem, 99%). Nine agents had > or = 95% activity against Enterobacteriaceae from urinary tract infection (ciprofloxacin, 95%; cefotetan, 97%; aztreonam, cefotaxime, ceftazidime, ceftizoxime, ceftriaxone and netilmicin, 98% each; imipenem, 99%). Seventeen agents had activity against > or = 95% of Staphylococcus aureus strains. Susceptibility of Pseudomonas aeruginosa isolates ranged from 2% to 91%.

Acinetobacter↗
PubMed1999

Role of the individual interferon systems and specific immunity in mice in controlling systemic dissemination of attenuated pseudorabies virus infection.

The importance of each of the two interferon (IFN) systems in impeding herpesvirus replication and in stimulating virus-specific lymphocytes to control an acute systemic infection is not completely understood. To further our knowledge, pseudorabies virus, attenuated by deletion of the glycoprotein E gene to impair its neurovirulence and by deletion of the thymidine kinase gene (gE-TK-PRV), was used to infect wild-type 129Sv/Ev and congenic mice with immune system-associated genetic deficiencies. Mice with mature B and T lymphocytes but lacking either one or both functional receptors for members of each of the two IFN families were infected with gE-TK-PRV. At 3 and 7 but not 14 days after infection, replicating gE-TK-PRV could be isolated only from livers or spleens of mice lacking the receptors for both IFN families, and these mice survived the infection. Therefore, functional IFN receptors were not required to induce a protective immune response against an acute infection with gE-TK-PRV. Furthermore, PRV-specific antibodies of all immunoglobulin G isotypes were produced in these mice. Mice without mature B and T lymphocytes and lacking either one or both functional receptors for members of each of the two IFN families were also infected with gE-TK-PRV. Three days after infection, replicating virus could be isolated only from mice lacking both mature B and T lymphocytes and functional IFN receptors, and these mice were not able to clear the virus. We present evidence that mice with an intact gamma IFN system but without mature B and T cells were able to prevent systemic dissemination of gE-TK-PRV.

Animals↗
PubMed1999

Early results of laparoscopic gastric banding compared with open vertical banded gastroplasty.

BACKGROUND: The introduction of laparoscopy and the increasing awareness that surgery is the only efficient long-term treatment for morbid obesity have been followed by an enormous increase in the demand for bariatric surgery. We introduced laparoscopic gastric banding (GB) in 1995, after a 15-year experience with vertical banded gastroplasty (VBG). The aim of this article is to compare the early results of this new technique with those of VBG. METHODS: The charts of all the patients who underwent VBG (group A) between 1981 and 1995 were reviewed. The data for the patients who underwent laparoscopic GB (group B) between December 1995 and March 1998 were collected prospectively. Weight loss was compared between groups. All the complications arising during follow-up in the laparoscopy group were considered for analysis. In the VBG group, the complications during the first 18 postoperative months were taken into consideration. RESULTS: There were 197 patients in group A and 76 patients in group B. The ages and risk factors were similar in both groups, but the mean body weight (116 kg vs. 121 kg, P < 0.01) and the mean body mass index (BMI) (42.7 versus 45.5, P < 0.001) were significantly higher in the laparoscopy group. If the first 30 patients of group B are excluded, duration of surgery was not different between groups. Mortality was similar, but the postoperative morbidity was higher in the VBG group (23.8% vs. 8.0%, P < 0.005). The hospital stay was much shorter in group B. Weight loss was less after 6 and 12 months in group B but was similar after 18-24 months in both groups. During early follow-up as defined in the Methods section, overall morbidity and the need for reoperation were not different between groups. Most complications were noted among the first 30 patients operated on. CONCLUSIONS: Laparoscopic GB takes no longer to perform than VBG once the learning curve is over. It is associated with less postoperative morbidity and a much shorter hospital stay. Weight loss is slower after laparoscopic GB but is similar to that achieved after 18-24 months by VBG. With proper surgical technique, laparoscopic GB can be performed adequately with a very low rate of postoperative and long-term complications. Considering the high incidence of long-term complications after VBG, it is probable that laparoscopic GB will eventually replace VBG as the restrictive procedure of choice for morbid obesity.

Adolescent↗
PubMed1999

Determination of the antimicrobial susceptibilities of Canadian isolates of Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis. Canadian Antimicrobial Study Group.

The susceptibility of Canadian isolates of three respiratory tract pathogens (Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae) to several antimicrobial agents were tested by two different methods. Beta-lactamase was produced by 68/211 (32.2%) of H. influenzae isolates and 64/75 (85.3%) of M. catarrhalis isolates. For S. pneumoniae, 19/156 (12.2%) isolates were resistant to penicillin (MIC > or = 0.12 mg/L) and two isolates had MICs of 1.5 mg/L. For some combinations of agents and organisms, different methods gave different values for the proportion of isolates susceptible. Regardless of methodology, for H. influenzae, the most active antimicrobials based on proportion of strains susceptible were ciprofloxacin (100%) and cefpodoxime (98.5-100%). For M. catarrhalis, the most active agents were azithromycin, cefaclor, cefixime, cefpodoxime, cefuroxime, ciprofloxacin, clarithromycin and loracarbef (100% each); the least active was ampicillin. Against penicillin-sensitive and -resistant pneumococci, the activity was not significantly different for azithromycin and clarithromycin (93.4-100%) and ciprofloxacin (MIC90 2.0 and 1.5 mg/L, respectively) but was different for cefuroxime (99.3% and 31.6%, respectively), cefaclor (MIC90 0.75 and > or = 256 mg/L, respectively), cefpodoxime (MIC90 0.047 and 1.5 mg/L, respectively) and loracarbef (MIC90 0.75 and > or = 256 mg/L, respectively). This study indicates the increasing incidence, in Canada, of beta-lactamase resistance in H. influenzae and M. catarrhalis and penicillin resistance in S. pneumoniae.

Anti-Bacterial Agents↗
PubMed1998

Indirect immobilization of recombinant proteins to a solid phase using the albumin binding domain of streptococcal protein G and immobilized albumin.

Immobilization of proteins to a solid phase leads to denaturation of the adsorbed molecules which may subsequently affect biological interactions. However, for many applications maintenance of the native structure is desired. Therefore, an indirect immobilization system was developed, based on binding of the albumin binding domain (ABP) of streptococcal protein G to rat serum albumin (RSA) precoated on a solid phase (RSA-microtiter plates). Escherichia coli vectors were adapted for production of recombinant protein fused to ABP and the 6 X His-tag. The expressed ABP tag was found to form homodimers. Plasmon resonance was used to study the interaction between an ABP fusion protein and immobilized RSA. Apparent on- and off-rates were calculated using a model for a bivalent analyte (k(a1) = 3.37 x 10(4) M(-1) s(-1), k(d1) = 1.23 x 10(-4) s(-1)). Thus, the stability of the ABP-RSA interaction can be explained by a slow off-rate. This was confirmed by chase experiments in an ELISA format. The ABP-RSA interaction remained stable after addition of different albumins. This immobilization system was used for the development of an ELISA to detect antibodies against Borna disease virus protein p40. The use of RSA-microtiter plates for indirect immobilization of ABP fusion protein was shown to be superior to direct adsorption on plastic. To obtain maximal antibody binding ten times less antigen was needed for indirect immobilization compared to direct adsorption. The binding capacity of the RSA-microtiter plates was determined to be about 0.8 pmol of monomeric ABP protein.

Adsorption↗
PubMed1998

[Has laparoscopy changed the surgical approach in gastroesophageal reflux? Apropos of an experience with 63 cases of gastroesophageal reflux treated by laparoscopy].

INTRODUCTION: Indications for surgery in gastrooesophageal reflux disease (GERD) have decreased significantly since the introduction of proton pump inhibitors. At the same time there has been renewed surgical interest in this disease triggered by the development of laparoscopy. We present our results with laparoscopic treatment of GERD and the change in our surgical approach to the condition during the past few years. METHODS: All patients admitted to the surgical department underwent prior evaluation by a gastroenterologist. Indications for surgery were resistance to medical therapy in 30 cases, recurrence of GERD after cessation of treatment in 25 cases and personal preference of the patient when maintenance therapy was necessary in 6 cases. The data were reviewed and the patients contacted during the first trimester of 1998 to evaluate long-term results. RESULTS: 63 patients were operated on between 1991 and July 1997. Rossetti-Nissen fundoplication was performed routinely until March 1995. Thereafter, the type of antireflux surgery has been chosen according to the preoperative evaluation of the patients, including endoscopy, oesophageal manometry and gastric emptying studies. There was no mortality and, except for one case, only minor morbidity. Four patients required reoperation, two for severe gas bloat syndrome and two for recurrence of GERD. Overall, the long-term follow-up shows that 93 patients are satisfied or very satisfied with their outcome (Visick 1 or 2). 5% of the patients need daily medication for heartburn, 5% complain of occasionally disturbing dysphagia, and 12% of sometimes distressing gas bloat. More patients have gas bloat after the Rossetti-Nissen procedure than after the Nissen or Toupet fundoplications. CONCLUSIONS: The enthusiasm of surgeons for the laparoscopic approach to GERD has prompted renewed interest in the pathophysiology of the disease. Consequently, indications for surgery are better defined, surgical technique is chosen according to the individual patient based on objective preoperative studies and follow-up has improved. In this setting, laparoscopic fundoplication represents an effective treatment for GERD. It is associated with lower postoperative morbidity than open surgery and represents the first choice when surgery is indicated.

Adult↗
PubMed1998

On the analysis of iodine-129 and iodine-127 in environmental materials by accelerator mass spectrometry and ion chromatography.

Based on a review of literature about the abundances of 129I (T1/2 = 15.7 Ma) in the environment we show that there is a severe lack of knowledge, in particular about natural, pre-nuclear levels. Among the two analytical techniques which are sensitive enough to investigate 129I in environmental materials, namely radiochemical neutron activation analysis (RNAA) and accelerator mass spectrometry (AMS), only AMS is capable of covering the natural, pre-nuclear levels. Since such AMS measurements require chemical separation of iodine from the matrix, a wide variety of separation schemes are necessary for environmental analyses. We report here on such schemes for the analysis of soils, plants and soft tissue. They are applied exemplarily to analyses of soils from the vicinity of Chernobyl. For chemical separations prior to analysis, contamination control and blank analyses are essential. Here, we discuss quality control procedures in detail, both for RNAA and AMS. In the case of AMS we use ion-chromatography (IC) for the determination of stable iodine. The IC analysis is included in the separation schemes for environmental materials. First AMS-analyses of terrestrial biospheric materials demonstrate that natural environmental levels of 129I are lower than previously deduced from investigations using RNAA, but higher than expected from model calculations. AMS is capable of providing the missing knowledge about the radioecology of 129I.

Air Pollutants, Radioactive↗
PubMed1998

Rabbit monoclonal Fab derived from a phage display library.

Rabbit monoclonal antibodies (RmAb) are not routinely obtained by eukaryotic cell fusion techniques. Therefore, we have applied phage display technology to produce a recombinant rabbit Fab molecule directed against the KLH model antigen. The Fab fragments selected from the rabbit phage display library were subcloned in an expression vector to permit the production of a fusion protein comprising a dimer of bacterial alkaline phosphatase (phoA). This fusion protein was directly produced into the periplasmic space of Escherichia coli. We show that a crude extract containing these conjugates can be used in a direct enzyme immunoassay, as exemplified in the case of the KLH antigen.

Alkaline Phosphatase↗
PubMed1998

Prokaryotic expression of porcine epidemic diarrhoea virus ORF3.

Wild type (wt) and cell culture adapted (ca) strains of the coronavirus PEDV differ in their ability to cause diarrhea in neonate piglets: the wt strains are virulent; the ca strains are attenuated. Comparison of the available nucleotide sequences obtained from the different viral isolates revealed almost complete sequence identity with the exception of variations and truncations in open reading frame 3 (ORF3) observed exclusively in ca-PEDV isolates. In order to study the biological function(s) of the putative ORF3 product, the molecule was expressed as a heterodimeric fusion protein in E. coli. ORF3 was fused in frame to the alkaline phosphatase gene. Simultaneously, the construct was designed to form specific heterodimers by inclusion of the well known leucine zipper motiv of Jun and Fos. The heterodimerization partner contained the E. coli heat-labile enterotoxin subunit B (LTB) to allow specific binding to the eukaryotic cell receptor GM1. Our results indicate that heterodimeric fusion protein containing a truncated form of ORF3 was produced in high amounts, carried the expected ORF3 epitope, showed phosphatase activity, and was able to bind to the GM1 receptor. In contrast, a fusion protein containing the entire sequence of the ORF3 product was produced in minute amounts, indicating that it may have biological activity in prokaryotes, which led to the reduction of the amounts of proteins expressed.

Animals↗