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Biomedical subjects

A Joss

Publications and source records attributed to A Joss.

At least 19 recordsLinked to original sources
PubMed2004

Computer-aided monitoring and operation of continuous measuring devices.

Extended studies of measuring and control systems in activated sludge plants at EAWAG revealed that the measuring devices remain the weakest point in control applications. To overcome this problem, a software package was developed which analyses and evaluates the residuals between a reference measurement and the sensor and collects the information in a database. The underlying monitoring concept is based on a two-step evaluation of the residuals by means of statistical evaluations using control charts with two different sets of criteria. The first step is a warning phase in which hints on probable errors trigger an increase in the monitoring frequency. In the second step, the alarm phase, the error hypothesis has to be validated and should allow immediate and targeted reactions from the operator. This procedure enables an optimized and flexible monitoring effort combined with an increased probability of early detection of systematic measuring errors. Beside the monitoring concept, information about the measuring device, the performed servicing actions and the responsibilities is stored. Statistical values for the quantitative characterization of the measuring system during operation will be given. They are needed to parameterise controllers or to guarantee the accuracy of the instrument in order to allow reliable calculations of effluent tax. In contrast to other concepts, not only is the measuring device examined under standard conditions, but so is the entire measuring chain from the liquid to be analysed to the value stored in the database of the supervisory system. The knowledge of the response time of the measuring system is then required in order to allow a comparison of the corresponding values.

Computers↗
PubMed2003

Comparison of analytical methods for the evaluation of antibody responses against epitopes of polymorphic protein antigens.

Surface exposed protein antigens of the malaria parasite Plasmodium falciparum frequently harbor multiple dimorphic amino acid positions. These are associated with parasite immune evasion and represent a major obstacle for subunit vaccine design. Here, we have analyzed the flexibility of the humoral immune response against a semiconserved sequence (YX(44)LFX(47)KEKMX(52)L) of the key malaria blood stage vaccine candidate merozoite surface protein-1 (MSP-1). Monoclonal antibodies (mAbs) raised against one of the six described natural sequence variants of MSP-1(43-53) were analyzed for cross-reactivity with the other allelic forms, which differ in one to three positions from the immunizing sequence. Enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) spectroscopy demonstrated marked differences in mAb binding avidity to the variant sequences and isothermal titration calorimetry (ITC) provided evidence for a very low affinity of some of the interactions. In immunofluorescence analysis (IFA) and Western blotting analysis, the mAbs nevertheless stained all analyzed parasite clones expressing MSP-1(43-53) variant sequences. When used for the evaluation of humoral immune responses in clinical malaria vaccine trials, these two commonly used methods may thus not be suitable to distinguish biologically functional high affinity antibody responses from irrelevant low-affinity cross-reactivities.

Amino Acid Sequence↗
PubMed2002

How to detect current toxoplasma infection.

This study seeks to identify the best way to detect current toxoplasma infection for district general hospital laboratories. One hundred 'ordinary' and 174 'difficult' sera are categorised into either an 'evidence' or 'no evidence' group for current toxoplasma infection. Twelve test protocols are investigated using different combinations of one whole antibody latex test (Eiken Toxoreagent), one in-house specific IgG enzyme-linked immunosorbent assay (ELISA) and three specific IgM assays (Toxo-ISAGA, in-house BAM ELISA IgM and Toxonostika ELISA M). The Eiken latex and in-house IgG assays produced significantly fewer false-negative results than were obtained with the single IgM test or the IgG and IgM test protocols (P<0.05), but a greater number of false-positive results (102/274 and 115/274, respectively). Of the IgM assay test protocols, the three IgM assays in combination produced the least number of false-negative results (1/274). However, a significantly greater number of false-positive results were produced than with one or two IgM tests or an IgG and any IgM test in combination (P<0.001). We recommend testing with three IgM tests, or a whole antibody (Eiken) or IgG-specific assay, and that positive or clinically important negative samples be referred to a reference laboratory for confirmation.

Animals↗
PubMed2001

Comparison of the clinical effects and gingival abrasion aspects of manual and electric toothbrushes.

AIMS: The clinical effects and gingival abrasion aspects of 2 electrical tooth-brushes (Braun Oral-B Plak Control Ultra and the novel development Braun Oral-B Plak Control 3D) were to be compared with conventional manual tooth-brushing. MATERIAL AND METHODS: In a cross-over study, 26 dental student volunteers participated and were assigned to 1 of 3 groups. Following instruction in the use of the electric as well as manual toothbrushes, the volunteers were timed for 2 min each day to apply one electric or the manual toothbrush, respectively, during 3 experimental phases of 2 weeks. No other methods of tooth cleaning were to be performed except the one specified for the respective test period. When brushing manually, the Bass toothbrushing technique was applied. Between each test period, a recovery period of 1 week was allowed during which no oral hygiene was performed at all. At the start and the end of each of the experimental periods, the extension of plaque deposits from the gingival margin in coronal direction was assessed using the Turesky et al. modification of the Quigley and Hein plaque index. Presence or absence of gingival inflammation was evaluated by bleeding and probing (BOP). The extent and severity of gingival abrasions were assessed by use of a modified method of Breitenmoser et al. and adapted by Danser et al. RESULTS: The plaque-reducing effect was similar in all groups with the same cleaning regime. For that reason, the result of the different experimental phases with the respective cleaning modalities were collapsed. Cleaning with the Braun Oral-B Plak Control Ultra electric toothbrush resulted consistently in the lowest plaque scores when compared to both the Braun Oral-B Plak Control 3D and the manual toothbrush. Although the differences in plaque reduction were statistically significant between cleaning with Braun Oral-B Plak Control Ultra and 3D, they were small and of questionable clinical relevance. No significant differences in plaque reductions were found between manual brushing and any of the 2 electric brushes. Gingival abrasions were least pronounced following brushing with the Braun Oral-B Plak Control 3D electric toothbrush. However, no significant differences in gingival abrasion were encountered following brushing with the Braun Oral-B Plak Control Ultra electric in comparison with the manual toothbrush. CONCLUSIONS: The results of the present study have shown that in a group of dental students trained in manual brushing technique, where efficacy was similar with the 3 toothbrushes tested, there is no evidence of greater gingival abrasion with either Braun Oral-B Plak Control Ultra or 3D when compared with a manual brush.

Adult↗
PubMed2001

[Marginal fit of dental restorations and the periodontium in Swiss army recruits].

The present study analyzed the relationship between periodontal health adjacent to filled and unfilled tooth sites in young men (recruits). The status of oral health of 419 Swiss army recruits, aged 19 to 20 years was assessed by determining Plaque Index (PI), Retention Index (RI) and Gingival Index (GI) as well as Pocket Probing Depth (PPD) and Probing Attachment Loss (PAL). In addition, the level of alveolar bone was measured using digitized bite-wing radiographs with an enlargement of 4.5x. Filling margins were assessed and the distance between the alveolar bone crest and the cemento-enamel junction (CEJ) measured to the nearest one tenth of a millimeter. These data were compared with the clinical parameters. A total of 8'050 sites were examined. 765 or 9.5 of the sites in the posterior area were filled. 119 of them showed filling overhangs larger than 0.2 mm. Thus, 1.5 % of the examined sites had a significant overhanging margin. All clinical parameters had greater values at filled than at unfilled sites. The differences were statistically not significant. Even the sites with margins overhanging more than 0.8 mm (n=14) did not show significantly different parameters compared to unfilled sites. The comparison with a similar study involving recruits 11 years earlier assessed that the recruits of 1996 had less and smaller filling overhangs. This, in turn, means that, in Switzerland restorative dentistry in young males has been markedly improved during the 1980's and 1990's.

Adult↗
PubMed2000

IL-10 directly acts on T cells by specifically altering the CD28 co-stimulation pathway.

IL-10 induces T cell anergy in numerous mouse models and specific immunotherapy of allergy in humans. Here, we demonstrate that IL-10 directly acts on T cells which are stimulated via CD28 by efficiently blocking proliferation and cytokine production. T cells tolerized by IL-10 showed high viability and the unresponsive state was reversed by anti-CD3 monoclonal antibody (mAb) stimulation and IL-2, but not by anti-CD28 mAb stimulation. Signal transduction via CD28 requires CD28 tyrosine phosphorylation and binding of phosphatidylinositol 3-kinase. IL-10 inhibited tyrosine phosphorylation of CD28; thus, the phosphatidylinositol 3-kinase binding to CD28 was blocked. Consequently, IL-10 inhibited the antigen-induced secretion of both Th1 and Th2 cytokines, including IL-2, IFN-gamma, IL-4, IL-5 and IL-13. Furthermore, neutralization of endogenously produced IL-10 significantly increased T cell proliferation and both Th1 and Th2 cytokine production in vitro. Using superantigen stimuli, T cell suppression by IL-10 was merely induced at low doses when co-stimulation by CD28 was essential. Together, these data demonstrate that IL-10 directly acts on the CD28 signaling pathway and this represents an important T cell suppression mechanism leading to anergy.

Animals↗
PubMed2000

Ecological, energetic and economic comparison of anaerobic digestion with different competing technologies to treat biogenic wastes.

In order to get more detailed information for better decision making in future biogenic waste treatment, different processes to treat biogenic wastes in plants with a treating capacity of 10,000 tons of organic household wastes per year were compared. The comparison included life cycle assessments as well as economic considerations for different treating methods. Measurements on compost plants showed that methane emissions are higher than estimated so far. With the tools ECOINDICATOR and UBP anaerobic digestion shows to be advantageous as compared to composting, incineration or combination of digestion and composting, mainly because of a better energy balance. In fully enclosed, professional treatment plants, the specific biotechnological treatment costs are in the range of about 150.-sFr/ton for aerobic, anaerobic and combined technologies. It can be concluded, that anaerobic processes will become considerably more important in the future mainly for ecological reasons.

Bacteria, Anaerobic↗
PubMed1999

An altered peptide ligand specifically inhibits Th2 cytokine synthesis by abrogating TCR signaling.

Altered peptide ligands (APL) can modify T cell effector function by their diversity in binding to the TCR or MHC class II-presenting molecules. The capacity to inhibit Th2 cytokine production by allergen-specific T cells would contribute to combating allergic inflammation. The presence of APL generated by Ala-substitutions in a synthetic dodeca-peptide spanning an immunodominant epitope of bee venom phospholipase A2 (PLA) was investigated in human T cells. Four of five substituted peptides reduced proliferation, IL-4, and IFN-gamma production by cloned PLA-specific Th0 cells proportionately. However, one APL, PLA-F82A, inhibited IL-4 but had no effect on IFN-gamma production. This uncoupling of IL-4 from IFN-gamma production was also observed on immunogenic restimulation of the cloned T cells pre-exposed to the APL/APCs. It appeared to result from lower affinity of binding to MHC class II by the APL compared with the native peptide. The APL also inhibited IL-4 production by polyclonal T cells. In consequence of the change in cytokine secretion, the production of IgG4 in vitro increased by PLA-F82A stimulation, compared with the native peptide. Exposure of the cloned T cells to either the APL or the native peptide, in the absence of professional APC, induced anergy such that proliferation and production of IL-4, IL-5, and IL-13 was abrogated on immunogenic rechallenge. Defective T cell activation appeared to result from alterations in transmembrane signaling through the TCR, specifically to lack of tyrosine phosphorylation of the tyrosine kinase, ZAP-70.

Clonal Anergy↗
PubMed1998

Generation of chimeric monoclonal antibodies from mice that carry human immunoglobulin Cgamma1 heavy of Ckappa light chain gene segments.

Gene targeting in mouse embryonic stem (ES) cells was used to replace (i) the mouse immunoglobulin heavy chain (IgH) Cgamma2a gene segment (mCgamma2a) with the human Cgamma1 gene segment (hCgamma1), and (ii) the mouse immunoglobulin light chain (IgL) Ckappa gene segment (mC kappa) with its human counterpart (hC kappa). ES cells carrying these gene conversions were used to generate chimeric mice that transmitted the human alleles through the germ line. Mice homozygous for both gene alterations were generated by breeding. Serum from homozygous mutant mice contained comparable amounts of antibodies with chimeric kappa or mouse lambda light chains but only small fractions of basal serum IgG or antibodies elicited against immunizing agents contained chimeric heavy chains. A relative increase in immunogen-specific hCgamma1 antibodies was seen following immunization in combination with the saponin adjuvant QS-21. The effect of this was to shift the IgG1-dominated response to an IgG subclass profile that included significant amounts of IgG2a, IgG2b and IgG3 and chimeric IgG. The amounts of antibody secreted by hybridomas derived from mutant and wild-type mice were similar. Sequencing confirmed correct splicing of hCgamma1 and hCkappa gene segments to mouse J gene segments in hybridoma Ig gene transcripts. In conclusion, IgHhCgamma1/IgLhCkappa double mutant mice provide a useful animal model for deriving humanized antibodies with potential applications in immunotherapy and diagnostics in vivo as well as for investigating hCgamma1 associated functions.

Animals↗
PubMed1997

Reproducibility of automated periodontal probing around teeth and osseointegrated oral implants.

Three different probing devices (Audio-Probe, Florida-Probe, Peri-Probe) were tested in order to determine the clinical probing depth (CPD) around clinically stable oral implants and their homologous teeth and to evaluate their reproducibility. In all 37 patients, in the age range of 24-80 years, who had undergone periodontal therapy and placement of 1 or more oral implants (ITI), were selected for the study. The CPD was determined on 75 oral implants in total and at 4 sites of both the implants and the control teeth at 3 visits, each 1 week apart. At the 1st visit, the Florida-Probe and the Audio-Probe were used. At the 2nd visit, the Florida-Probe and the Peri-Probe and, at the 3rd visit, again, the Florida-Probe and the Audio-Probe were used. At each visit bleeding on probing (BOP) was registered. A statistically significant (P < 0.05) difference between the mean scores of implant and tooth sites was found showing slightly higher values for implant sites. A tendency for the deeper pockets to bleed more frequently than the shallow pockets was observed. The comparisons of differences of the readings of the Audio-Probe on 2 different occasions were smaller than for the Florida-Probe. However, comparisons between 2 different probes showed significantly greater measurement errors than when comparing the probes alone. There was a tendency for the Peri-Probe to yield the highest and the Audio-Probe the lowest values in inflamed sites. It was concluded that all 3 probing devices appeared to have adequate reproducibility both around teeth and oral implants. For clinical use in daily practice, the Audio-Probe was found to be the most simple device with the highest reproducibility.

Adult↗
PubMed1995

Threshold of tactile sensitivity perceived with dental endosseous implants and natural teeth.

The aim of this study was to determine the threshold of tactile perception of endosseous dental implants and to assess the relative difference of that threshold between implants and teeth. Twenty-two subjects with implants of the ITI Dental Implant System were included in the study. All implants served as abutments for single tooth crowns and had been in function for a minimum of 1 year. A strain gauge glued to the shaft of an amalgam plugger served as a force sensor. It transformed the elastic deformation exerted onto the shaft into an electronic signal for recording. By use of the amalgam plugger, a continuously increasing force was exercised on the implants or teeth until the first sensation of touch was indicated by the patient. Statistical analysis revealed threshold values for the implants ranging from 13.2 to 189.4 g (1 g = 0.01 N) (mean 100.6; SD 47.7), while a range of 1.2 to 26.2 g (mean 11.5; SD 11.5) was found for control teeth. Thus, the mean threshold values for implants were 8.75 times higher than for teeth. This difference was highly statistically significant. A general linear models procedure was applied to determine the influence of patient age, jaw, implant position and the threshold values of teeth on the measurements obtained for implants. Only gender and the threshold values for contralateral teeth had a significant influence. These 2 parameters together explained 27% of the variability in threshold measurements. It is concluded that a more than 8-fold higher threshold value for tactile perception exists for implants compared with teeth.

Adolescent↗
PubMed1994

Bleeding on probing. A parameter for monitoring periodontal conditions in clinical practice.

The present study is a follow-up report on the use of bleeding on probing (BOP) as a clinical indicator for disease progression or periodontal stability, respectively. Following active periodontal therapy, 39 patients were incorporated in a program of supportive periodontal therapy for a period of 53 months with recall intervals varying between 2-8 months. The patients received supportive therapy 7 to 14 x. At the beginning of each maintenance visit, the tissues were evaluated using BOP. Reinstrumentation was only performed at sites which bled on probing. However, supragingival plaque and calculus were always removed. Probing depth and probing attachment levels were determined after active treatment and at the conclusion of the study. Progression of periodontal disease was defined by a measured loss of probing attachment of 2 mm or more. During the observation period, 4.2% of all the sites lost attachment. Approximately 50% of these losses were due to periodontal disease progression, while the other half was the result of attachment loss in conjunction with recession of the gingiva. 2/3 of all the sites which lost attachment were found in a group of patients which presented a mean BOP > or = 30%. In a group of patients with a mean BOP of < or = 20%, only 1/5 of the loser sites were found. This clearly indicated, that patients with a mean BOP of < or = 20% have a significantly lower risk for further loss of probing attachment at single sites.

Dental Prophylaxis↗
PubMed1992

Bleeding on probing as it relates to probing pressure and gingival health in patients with a reduced but healthy periodontium. A clinical study.

A previous study demonstrated that the bleeding on probing (BOP) test using uncontrolled forces may result in a proportion of false positive readings when used as a parameter for inflammation. A strong possibility exists for the traumatization of clinically healthy gingival tissues if a probing force exceeding 0.25 N is applied. While these results originated form young dental hygienists exhibiting excellent oral hygiene, the aim of the present study was to evaluate the relationship between probing pressures and gingival conditions in patients with a history of treated periodontal disease, i.e., in situations with a reduced but healthy periodontium. 10 patients who had been enrolled in a periodontal maintenance program following treatment of moderate to advanced chronic inflammatory periodontal disease consented to participate in the study. They were all selected on the basis of a record of excellent oral hygiene practices for at least 2-6 years and almost complete absence of clinical inflammation following successful periodontal therapy. Applying a probing force of 0.125, 0.25, 0.375 and 0.5 N in the 4 jaw quadrants, respectively, at 2 different occasions with an interval of 10 days, bleeding on probing was assessed. Oral hygiene and gingival conditions were determined using the criteria of the plaque and gingival index systems. All subjects showed significant increases in mean BOP% with increasing probing force applied (2.5%-7.9%). Regression analysis revealed an almost linear correlation and a significant correlation coefficient between BOP% and probing force. Almost identical slope inclinations were found when the 6 subjects with the lowest mean BOP% at 0.25 N were compared with the regression analysis of the total group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Periodontal conditions in Swiss Army recruits.

The purpose of the present study was to assess the oral hygiene and periodontal conditions of a young male population representative for Switzerland. 757 Swiss Army recruits were examined for their oral health status including the assessment of Plaque Index (PlI), Retention Index (RI) and Sulcus Bleeding Index (SBI) as well as Probing Depth (PD) and Loss of Probing Attachment (LA). All the teeth of the right maxillary and mandibular dental arch were evaluated on four aspects. One recruit yielded a status of juvenile periodontitis and was excluded from further analysis. 2.3% of the teeth had been lost, mainly as a result of orthodontic therapy. Mean PlI and SBI for all 756 recruits approximated 0.6, while the mean RI was around 0.1. The mean PD was 2.3 mm, and the mean LA of 0.9 mm was measured. PD and LA were slightly higher on proximal than on buccal or oral aspects. Site specific analysis for all parameters are presented. Since only 0.4% of the recruits showed probing depths of greater than or equal to 5 mm and only 1% of the subjects showed LA greater than or equal to 4 mm on any surfaces it may be concluded that severe signs of chronic adult periodontitis are absent in 99% of young male Swiss citizens.

Adult↗