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Biomedical subjects

L Kaiser

Publications and source records attributed to L Kaiser.

At least 19 recordsLinked to original sources
PubMed2006

Robust analysis of short echo time (1)H MRSI of human brain.

Short echo time proton MR Spectroscopic Imaging (MRSI) suffers from low signal-to-noise ratio (SNR), limiting accuracy to estimate metabolite intensities. A method to coherently sum spectra in a region of interest of the human brain by appropriate peak alignment was developed to yield a mean spectrum with increased SNR. Furthermore, principal component (PC) spectra were calculated to estimate the variance of the mean spectrum. The mean or alternatively the first PC (PC(1)) spectrum from the same region can be used for quantitation of peak areas of metabolites in the human brain at increased SNR. Monte Carlo simulations showed that both mean and PC(1) spectra were more accurate in estimating regional metabolite concentrations than solutions that regress individual spectra against the tissue compositions of MRSI voxels. Back-to-back MRSI studies on 10 healthy volunteers showed that mean spectra markedly improved reliability of brain metabolite measurements, most notably for myo-inositol, as compared to regression methods.

Adult↗
PubMed2006

Analysis of factors that contribute to treatment failure in patients with community-acquired pneumonia.

To determine the causes of treatment failure and to evaluate the prognostic factors in patients hospitalized for community-acquired pneumonia, a prospective, observational study of 228 adult patients hospitalized for a community-acquired pneumonia in the University Hospital of Geneva and the La Chaux-de-Fonds Community Hospital, Switzerland, was conducted. The percentage of patients who failed to improve (as defined by guidelines of the Infectious Disease Society of America) and the causes of treatment failure were assessed, and patients who failed to improve under antimicrobial therapy were compared with those who did improve. In the 54 (24%) patients who failed to improve, a mean increase in length of hospitalization of 4 days was observed. Most causes of treatment failure could be attributed to host factors (61%) rather than to the pathogen (16%) or to an inappropriate antibiotic regimen (3%). After adjusting for potentially confounding variables, concomitant neoplasia (OR 3.25; 95%CI 1.11-9.56), neurological disease (OR 2.34; 95%CI 1.07-5.13), and aspiration pneumonia (OR 2.97; 95%CI 29-6.86]) were associated with failure to improve, whereas monocytosis improved prognosis (OR 0.40; 95%CI 0.20-0.80). Almost one out of four patients hospitalized for community-acquired pneumonia failed to respond to empirical antibiotic treatment. Aspiration pneumonia, concomitant neoplasia, and neurological disease were factors positively associated with failure to improve, whereas monocytosis was linked to a better prognosis.

Adolescent↗
PubMed2005

Effects of plant protease inhibitors, oryzacystatin I and soybean Bowman-Birk inhibitor, on the aphid Macrosiphum euphorbiae (Homoptera, Aphididae) and its parasitoid Aphelinus abdominalis (Hymenoptera, Aphelinidae).

Transgenic plants expressing protease inhibitors (PIs) have emerged in recent years as an alternative strategy for pest control. Beneficial insects such as parasitoids may therefore be exposed to these entomotoxins either via the host or by direct exposure to the plant itself. With the objective of assessing the effects of PIs towards aphid parasitoids, bioassays using soybean Bowman-Birk inhibitor (SbBBI) or oryzacystatin I (OCI) on artificial diet were performed on Macrosiphum euphorbiae-Aphelinus abdominalis system. OCI significantly reduced nymphal survival of the potato aphid M. euphorbiae and prevented aphids from reproducing. This negative effect was much more pronounced than with other aphid species. On the contrary, SbBBI did not affect nymphal viability but significantly altered adult demographic parameters. Enzymatic inhibition assays showed that digestive proteolytic activity of larvae and adults of Aphelinus abdominalis predominantly relies on serine proteases and especially on chymotrypsin-like activity. Immunoassays suggested that OCI bound to aphid proteins and accumulated in aphid tissues, whereas SbBBI remained unbound in the gut. Bioassays using M. euphorbiae reared on artificial diets supplemented with both OCI and SbBBI showed a fitness impairment of Aphelinus abdominalis that developed on intoxicated aphids. However, only SbBBI was detected in parasitoid larvae, while no PI could be detected in adult parasitoids that emerged from PI-intoxicated aphids. The potential impact of PI-expressing plants on aphid parasitoids and their combined efficiency for aphid control are discussed.

Animals↗
PubMed2005

Potential effects of plant protease inhibitors, oryzacystatin I and soybean Bowman-Birk inhibitor, on the aphid parasitoid Aphidius ervi Haliday (Hymenoptera, Braconidae).

Protease inhibitors (PIs) have been shown to cause lethal and sublethal effects on aphids depending on the kind of PI and aphid species. Therefore, these proteins might affect aphid parasitoids directly by inhibiting their digestive proteolysis or indirectly via their development in a less suitable host. In our study, the risk of exposure and the potential effects of soybean Bowman-Birk inhibitor (SbBBI) and oryzacystatin I (OCI) on the aphid endoparasitoid Aphidius ervi were investigated using artificial diet to deliver PIs. Immunoassays showed that both SbBBI and OCI were detected in the honeydew of aphids reared on artificial diet containing these recombinant proteins at 100 microg/mL. However, only SbBBI was detected in parasitoid larvae, while this PI could not be detected in adult parasitoids emerged from PI-intoxicated aphids. Enzymatic inhibition assays showed that digestive proteolytic activity of larvae and adults of A. ervi predominantly relies on serine proteases and especially on chymotrypsin-like activity. Bioassays using SbBBI and OCI on artificial diet were performed. A. ervi that developed on intoxicated aphids had impaired fitness. Thus development and parasitism success of parasitoids exposed to OCI were severely affected. On the contrary, SbBBI only altered significantly female size and sex ratio. Direct exposure to PIs through adult food intake did not affect female's longevity, while SbBBI and OCI (100 microg/mL) induced 69% and 30% inhibition of digestive protease activity, respectively. These studies made it possible to estimate the risk of exposure to plant PIs and the sensitivity of the aphid parasitoid A. ervi to these entomotoxins, by combining immunological, biochemical and biological approaches. First it pointed out that only immature stages are affected by PIs. Secondly, it documented two different modes of effect, according to the nature of the PIs and both host and parasitoid susceptibility. OCI prevented the development of A. ervi mainly due to the host susceptibility, whereas SbBBI only induced sublethal effects on the parasitoid, possibly due to both direct action on the parasitoid susceptible proteases, and host-mediated action through size reduction.

Animals↗
PubMed2005

Rational design of hypoallergens applied to the major cat allergen Fel d 1.

BACKGROUND: Allergen-specific immunotherapy is the only treatment for allergic disease providing long-lasting symptom relief. Currently, it is mainly based on the use of crude allergen extracts. The treatment may be improved by the use of genetically engineered allergens, hypoallergens, aiming at a more effective and safer therapy. OBJECTIVE: The aim of this study was to provide a rational design of hypoallergen candidates for immunotherapy by using structural information and knowledge of B and T cell epitopes of an allergen. METHODS: The three-dimensional structure of the major cat allergen Fel d 1 was systematically altered by duplication of selected T cell epitopes and disruption of disulphide bonds. Seven Fel d 1 derivatives were generated and screened for allergenic reactivity in comparison with recombinant Fel d 1 in competition-ELISA. The allergenicity was further evaluated in basophil activation experiments and T cell reactivity was assessed in a lymphoproliferation assay. RESULTS: Three out of seven Fel d 1 derivatives, with two duplicated T cell epitopes and one or two disulphide bonds disrupted, were carefully evaluated. The three derivatives displayed a strong reduction in allergenicity with 400-900 times lower IgE-binding capacity than recombinant Fel d 1. In addition, they induced a lower degree of basophil activation and similar or stronger T cell proliferation than recombinant Fel d 1. CONCLUSION: By a rational approach, we have constructed three Fel d 1 hypoallergens with reduced IgE-binding capacities and retained T cell reactivities. This strategy may be applied to any well-characterized allergen to improve immunotherapy for allergic patients.

Allergens↗
PubMed2004

Ganciclovir for severe cytomegalovirus primary infection in an immunocompetent child.

Described here is the unusual case of a previously healthy 17-month-old girl who developed severe cytomegalovirus (CMV) disease with prolonged fever and hepatitis. The severity of her illness required hospitalization and prompted antiviral treatment. Short-term intravenous ganciclovir treatment was associated with immediate and sustained resolution of the symptoms as well as a sharp decrease of CMV viremia. This observation suggests that antiviral therapy might be considered in select cases of severe primary CMV infection in immunocompetent children.

Cytomegalovirus↗
PubMed2004

Dose-response relationship in lethal and behavioural effects of different insecticides on the parasitic wasp Aphidius ervi.

Neurotoxic insecticides are widely used for crop protection and behavioural perturbations can be expected in surviving beneficial insects, including parasitoids of pest insects. The present study aims to investigate the relationship between the dose of insecticide parasitoids have been exposed to, and the subsequent ability of these parasitoids to respond to host-related cues. A four-armed olfactometer, a design widely used to observe orientation responses in various insects and parasitoids in particular, was chosen to investigate the dose-response relationship. The species studied was Aphidius ervi, a relatively generalist parasitoid of aphids, and commercialised for biological control and integrated pest management. Active ingredients with similar and different modes of action on the nervous system were compared: a pyrethroid (lambda-cyhalothrin), an organophosphate (chlorpyrifos), a carbamate (pirimicarb) and a carbamyltriazole (triazamate). Adult females were exposed to dry residues on glass for 24 h. LD50 were calculated and predicted a high risk of mortality at the field application rate. The effect of five increasing residual doses of each active ingredient was tested on responses to plant-host odour in the olfactometer, from sublethal doses to LD50, and up to LD70 for some products. It appeared that none of the doses of lambda-cyhalothrin, chlorpyriphos and pirimicarb had any effect on A. ervi responses to the odour from the aphid-infested plant (Myzus persicae on oilseed rape). But for triazamate, a significant dose-behavioural response was quantified and attraction to the odour was no longer significant in females surviving the LD50. The possible explanations for the presence or absence of effect, depending on the insecticide are discussed.

Animals↗
PubMed2004

Squamous cell carcinoma of the bladder presenting as vulvitis and cliteromegaly.

INTRODUCTION: Clitoral metastases are exceptionally rare. We present a case of a squamous cell carcinoma of the bladder presenting with a clitoral metastasis. CASE REPORT: We report the case of an 84-year-old lady with frequency, dysuria and a clitoral mass, which was found to be a poorly differentiated carcinoma on fine needle aspiration cytology. Cystoscopy revealed a moderate to poorly differentiated squamous cell carcinoma of the bladder. CONCLUSION: This is the first reported case of a squamous cell carcinoma of the bladder with clitoral metastasis. Clitoral metastases are exceptionally rare, with only seven previous cases reported in the literature. Although the commonest cause of cliteromegaly is hormonal, a metastatic carcinoma should be considered as part of the differential diagnosis in the elderly female.

Aged↗
PubMed2003

The use of near patient tests in influenza surveillance: Swiss experience and EISS recommendations.

Surveillance requires time for analysis and for the communication to physicians. In order to reduce this delay, a new surveillance system based on the use of a near patient test (NPT) has been evaluated. The high specificity of NPT together with the rapidity in obtaining the results, make these tests attractive for surveillance of influenza epidemic in community practice. Such surveillance has been used in several countries including Switzerland. Four different seasons - between 1999 and 2003 - of this type of surveillance experienced in Switzerland have been analysed. The heterogeneity in terms of intensity and type of strains detected during these four epidemics seasons allowed an efficient evaluation. The average gain of time with NPT compared to cell culture was nine days. Furthermore, training of participants appeared to be essential to assure the quality of the surveillance system. A statement on the use of NPTs for influenza surveillance has finally been endorsed by EISS members. Included are recommendations that the network should use the NPTs data, which provides additional information to the classical surveillance systems, as an "early warning" system of a change in influenza activity.

Disease Notification↗
PubMed2003

Human infection by a swine influenza A (H1N1) virus in Switzerland.

The isolation of A/Switzerland/8808/2002 provides further evidence of sporadic human infection by contemporary swine influenza A H1N1 viruses, antigenically and genetically distinct from H1N1 viruses circulating in the human population. Together with the recent emergence of human-swine-avian reassortant viruses in pig populations in Europe and North America, frequent transmission between swine and human populations emphasises the potential for the emergence in pigs of novel subtypes with the capacity to cause major human epidemics.

Agricultural Workers' Diseases↗
PubMed2003

IgE-mediated sensitization to predatory mites in Swedish greenhouse workers.

BACKGROUND: Predatory mites are used as biological pesticides worldwide for control of spider mites and other pests in greenhouses. The aim of this study was to investigate if predatory and spider mites give rise to sensitization among greenhouse workers who use biological pesticides. METHODS: Blood samples were collected from 31 greenhouse workers from Stockholm area who were using the predatory mites Phytoseiulus persimilis and Hypoaspis miles for control of pesticides. Immunoglobulin E (IgE) binding to extracts of P. persimilis and H. miles and of the spider mite Tetranychus urticae was analysed with sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. RESULTS: A total of 16 workers displayed IgE antibodies to one or more of the three mite species, 32% (n = 10) to P. persimilis, 52% (n = 16) to H. miles and 26% (n = 8) to T. urticae. At least 17 IgE binding components in the molecular weight ranging from 28 to >94 kDa were identified in P. persimilis. In H. miles, at least 11 components were detected, among them at least one major component at about 70 kDa. Twenty-four IgE binding components were found in T. urticae. CONCLUSIONS: In this study we have for the first time shown that the predatory mites P. persimilis and H. miles can cause IgE-mediated sensitization among greenhouse workers. The clinical relevance of sensitization to predatory mites needs to be investigated in further studies.

Adult↗
PubMed2003

Rapid antigen testing for the surveillance of influenza epidemics.

OBJECTIVE: To assess the use of a 'near patient' test for rapid antigen detection to obtain the more timely acquisition of data for the surveillance of influenza epidemics. METHODS: To the classical cell culture system used for the surveillance of influenza, a 'near patient' test was added. The cell culture method was applied for the detection of influenza virus in specimens sent to our laboratory. In contrast, the 'near patient' test was used directly by practitioners in their practices to screen patients for the presence of influenza virus antigen. RESULTS: The results for two seasons are presented. The 'near patient' test was able to detect a developing influenza epidemic with the same reliability as clinical consultation reports for influenza-like illness or the conventional culture method. However, the results obtained were available 9 days earlier on average, compared with cell culture. Because of this, results concerning the epidemics could be announced via the internet more rapidly. Although the 'near patient' test demonstrated a lower sensitivity than detection by conventional cell culture, the sensitivity was still sufficiently high to reveal the characteristics of the epidemics in the community. CONCLUSIONS: Rapid influenza testing is a reliable tool for influenza surveillance and, compared with traditional methods (virus detection on cell culture and monitoring of influenza-like illness), provides faster results. Although the 'near patient' test has limited sensitivity compared with cell culture, results were consistent over two seasons, and suggest that rapid testing should be part of a surveillance program.

Antigens, Viral↗
PubMed2003

Community-acquired pneumonia: causes of treatment failure in patients enrolled in clinical trials.

In order to determine the causes of treatment failure in community-acquired pneumonia (CAP) clinical trials, a MEDLINE search for all CAP studies published between 1990 and 1997 was performed. Prospective, randomized studies comparing the efficacy of two or more antibiotics in CAP were selected. Treatment failure was defined as persistent fever, deterioration of patient's condition, or a change in the prescribed antibiotic regimen. In 16% of the cases included in the clinical trials, the treatment of CAP is unsuccessful. A significant number of identified failure cases were owing to antibiotic side-effects. Resistant pathogens are an unusual cause of failure whatever the antibiotic used.

Aged↗
PubMed2002

Histological findings after colocystoplasty and gastrocystoplasty.

PURPOSE: We conducted a prospective, long-term assessment of the histological changes that can occur following bladder augmentation with colon or stomach. MATERIALS AND METHODS: Histological evaluations of biopsies from 44 consecutive patients undergoing augmentation (colocystoplasty in 26, gastrocystoplasty in 18) were performed. Patients underwent endoscopic assessment and tissue sampling at 2 or 4-year intervals following the initial augmentation procedure. Patients with less than 2 years of followup were excluded from the analysis. Specimens were taken from the native bladder, the augment segment (large bowel or stomach) and the anastomotic line. Sections (4 mu.) were examined using standard histological staining methods (hematoxylin and eosin and periodic acid-Schiff) and immunohistochemistry was performed for different markers of neoplasia, cellular proliferation and blood group antigens. Histological findings were correlated with the incidence of stone formation and urinary tract infection. RESULTS: Group 1 consisted of 20 patients undergoing colocystoplasty who met the criteria for study inclusion. Of the patients 10 (50%) had stones, 19 (95%) had a positive urine culture and 6 had no histological changes. While no cases of malignancy were identified, other forms of pathological change were noted in 14 of the 20 patients (70%). Group 2 included 15 patients undergoing gastrocystoplasty who met the criteria for study inclusion. No stones or malignancy were identified in this group. Positive urine cultures were recorded in 2 patients (13%), no histological changes were found in 6 and 9 (60%) had pathological changes. CONCLUSIONS: Periodic prospective biopsy evaluation of children who have undergone either colocystoplasty or gastrocystoplasty failed to reveal any histological evidence of malignancy after 10-year followup. However, histological evidence of a premalignant lesion 13 years after followup suggests that screening for premalignant lesions should be initiated no later than 6 to 10 years following enterocystoplasty.

Adolescent↗
PubMed2001

Study of cattle persistently infected with bovine viral diarrhea virus that lack detectable virus in serum.

OBJECTIVE: To determine whether cattle persistently infected with bovine viral diarrhea virus (BVDV) that lack virus detectable in serum by use of the immunoperoxidase microtiter assay (IPMA) can transmit the virus to susceptible herdmates and determine prevalence of these cattle. DESIGN: Clinical trial and serologic survey. SAMPLE POPULATION: 2 cattle and 1,952 blood samples. PROCEDURE: A persistently infected cow in which virus could not be detected in serum was housed with a BVDV-seronegative steer. Blood and nasal swab specimens were tested via virus isolation and serum virus neutralization. Parallel WBC preparations and sera from blood samples of 1,952 adult cows were screened for BVDV by use of IPMA. RESULTS: The steer seroconverted to BVDV within 4 weeks of contact with the cow. Virus was detected in sera and WBC of 5 adult cows that were verified as persistently infected by retest 3 weeks later. Cattle persistently infected with BVDV in which virus could not be detected in both serum and WBC by use of IPMA were not found. CONCLUSION AND CLINICAL RELEVANCE: Cattle persistently infected with BVDV in which virus cannot be detected in serum by use of IPMA may serve as virus reservoirs for infecting susceptible cattle. Persistent infection was detected at a prevalence of 0.26%. Screening adult cattle by use of IPMA on serum samples appears to be a reliable means of detecting persistent infection with BVDV. Prevalence of cattle persistently infected with BVDV that have negative results of IPMA on serum is extremely low.

Animals↗