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Biomedical subjects

D Hassler

Publications and source records attributed to D Hassler.

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

Transmission risk of Borrelia burgdorferi sensu lato from Ixodes ricinus ticks to humans in southwest Germany.

The risk of Borrelia burgdorferi infection and the value of antibiotic prophylaxis after tick bite are controversial. In this study, performed in two areas of southwestern Germany, ticks were collected from 730 patients and examined by the polymerase chain reaction (PCR) for B. burgdorferi. To assess whether transmission of B. burgdorferi occurred, the patients were clinically and serologically examined after tick removal and during follow-up examinations. Data from all tick bites gave a total transmission rate of 2.6% (19 patients). Eighty-four ticks (11.3%) were PCR positive. Transmission occurred to 16 (26.7%) of 60 patients who were initially seronegative and could be followed up after the bite of an infected tick. These results indicate that the transmission rate from infected ticks in Europe is higher than previously assumed. Examination of ticks and antibiotic prophylaxis in the case of positivity appears to be indicated.

Adolescent↗
PubMed1997

Cloning of a disintegrin metalloproteinase that processes precursor tumour-necrosis factor-alpha.

Tumour-necrosis factor-alpha (TNF-alpha) is a cytokine that contributes to a variety of inflammatory disease states. The protein exists as a membrane-bound precursor of relative molecular mass 26K which can be processed by a TNF-alpha-converting enzyme (TACE), to generate secreted 17K mature TNF-alpha. We have purified TACE and cloned its complementary DNA. TACE is a membrane-bound disintegrin metalloproteinase. Structural comparisons with other disintegrin-containing enzymes indicate that TACE is unique, with noteable sequence identity to MADM, an enzyme implicated in myelin degradation, and to KUZ, a Drosophila homologue of MADM important for neuronal development. The expression of recombinant TACE (rTACE) results in the production of functional enzyme that correctly processes precursor TNF-alpha to the mature form. The rTACE provides a readily available source of enzyme to help in the search for new anti-inflammatory agents that target the final processing stage of TNF-alpha production.

ADAM Proteins↗
PubMed1997

Structural features and biochemical properties of TNF-alpha converting enzyme (TACE).

Tumor necrosis factor-alpha is a potent cytokine, secreted primarily by activated monocytes and macrophages, that possesses a broad range of immunomodulating properties. Involvement of this cytokine has been validated in disease states such as arthritis and Crohn's disease and implicated in diverse neuroimmunological pathologies such as multiple sclerosis, Alzheimers and stroke. TNF-alpha is initially synthesized as a 26 kDa precursor molecule that is subsequently processed to the mature form by cleavage of the Ala76 Val77 bond. The 17 kDa carboxy-terminal protein is then secreted to function in a paracrine manner. The enzyme that processes precursor TNF-alpha has previously been identified as a microsomal metalloprotease called TNF-alpha converting enzyme (TACE). We have now purified and partially cloned the enzyme. TACE represents a novel target for therapeutic intervention in a variety of inflammatory and neuroimmunological diseases.

ADAM Proteins↗
PubMed1996

Tick infestation patterns and prevalence of Borrelia burgdorferi in ticks collected at a veterinary clinic in Germany.

A total of 4803 domestic and wild animals which were presented for examination at a veterinary clinic in north Baden, Germany over a period of 1 year were examined for tick infestation. A total of 434 nymphal and adult ticks were collected from 175 hosts. Ticks found belonged to the species Ixodes ricinus (385), Ixodes hexagonus (48), and Ixodes ventalloi (one). The polymerase chain reaction was used to examine 132 I. ricinus and 21 I. hexagonus for the presence of Borrelia burgdorferi. Twenty-two per cent of adult I. ricinus were infected as were one female and one larval I. hexagonus.

Animals↗
PubMed1996

Comparison of urinary bladder and ear biopsy samples for determining prevalence of Borrelia burgdorferi in rodents in central Europe.

PCR was used to compare urinary bladder and ear biopsy samples from four European species of wild rodents for the presence of Borrelia burgdorferi sensu lato. From 60 paired comparisons of bladder and ear biopsy samples, the PCR results were concordantly positive or negative in 43 samples (71.7%). Of the 17 which differed, 14 bladder samples were positive and ear samples were negative while the converse occurred for three samples. Thus ear biopsy samples led to a significantly lower estimate of infection than bladder biopsy samples. This suggests that the use of ear biopsy samples in epidemiological studies of B. burgdorferi in Central European rodents is likely to lead to underestimates of the prevalence.

Animals↗
PubMed1995

[Natural epidemiology of Lyme borreliosis with reference to clustered incidence of illnesses in the suburbs of a North Baden community].

Human infection with Borrelia burgdorferi, the causative agent of Lyme disease, is unusually common in the "Scheelkopf" area of the town Bruchsal in north Baden (Germany), a situation which has led to considerable publicity and public concern. This study was carried out in order to clarify this situation by determining the prevalence of B. burgdorferi in both the free-living tick populations (Ixodes ricinus) and the rodent population from the "Scheelkopf" as well as from surrounding control areas. The polymerase chain reaction (PCR) was used to determine the presence of infection in whole tick preparations and in mouse bladders. The prevalence of B. burgdorferi in freeland ticks ranged from 19% to 44% and in mice from 6% to 29% depending on the area studied. The "Scheelkopf", with prevalences for ticks and mice of 33% and 10% respectively, was not significantly different from the control areas. Our results indicate that there is a high risk of human infection throughout the study area. This is probably related to the intensive use of the area for gardens and the related recreational behaviour of the human population in conjunction with the high rate of infection prevailing in I. ricinus.

Animals↗
PubMed1994

[Reinfection with Borrelia burgdorferi in an immunocompetent patient].

A 54-year-old patient with an intact immune system developed Lyme disease three times within 4 years. The first time an erythema migrans occurred, which was successfully treated with oral doxycycline (100 mg twice daily for 20 days). Specific antibodies were subsequently demonstrated. Re-infection nonetheless occurred a year later, again as erythema migrans. Oral doxycycline in higher dosage (three times 100 mg daily for 20 days) failed to prevent generalization of the infection with rigor, head and neck aches, myalgia, fatigue and subfebrile temperatures. There was a marked increase in Borrelia-specific antibody titre. Parenteral treatment with cefotaxime (twice daily 3 g for 12 days) was curative. But 2 years later yet another re-infection occurred with classic erythema migrans, which regressed under doxycycline. The course of the disease in this case demonstrates that Borrelia-specific antibodies do not always protect against re-infection. This may have consequences for the possible development of a vaccine.

Animals↗
PubMed1992

[Lyme borreliosis in an endemic region in Europe. Prevalence of antibodies and clinical spectrum].

A representative sample of the population of two villages located in an area of North Baden where borreliosis is endemic was studied to ascertain the prevalence of antibodies against Borrelia burgdorferi and of clinical abnormalities. The aim of the study was to determine what clinical symptoms and signs were correlated with positive antibody status. Out of the 2928 inhabitants 1228 were investigated, and 207 of these (16.9%) were seropositive. Certain clinical abnormalities showed highly significant statistical correlations with positive antibody status. Arthritis (defined in terms of heat, redness and effusion) was noted in 34.3% of the seropositive patients, but in only 9.3% of seronegative patients (P less than 0.0001). Complaints of arthralgia were noted in 23.4% of seropositive patients and 13.3% of seronegative patients (P less than 0.001). Motor neuropathies showed similar correlation with seropositive status (12.0% vs 4.0%; P less than 0.001), as did sensory neuropathies (25.4% vs 6.7%; P less than 0.001). Differences were also noted in the prevalence of cardiac arrhythmias (ventricular extrasystoles, conduction abnormalities and intermittent tachyarrhythmias), which were found in 19.8% of the seropositive as against 3.0% of the seronegative subjects (P less than 0.001). The findings are evidence of a causal link between the listed clinical abnormalities and the presence of antibodies against Borrelia burgdorferi.

Adolescent↗
PubMed1992

[Nodular panniculitis: a manifestation of Lyme borreliosis?].

Infection with Borrelia burgdorferi can induce various skin manifestations. The type of skin manifestation and the histopathological picture depend on the stage of infection and vary from local inflammatory infiltrates to chronic atrophic skin disease. Involvement of subcutaneous tissue has been observed only very rarely. We report on two patients suffering from nodular panniculitis (Pfeifer-Weber-Christian) and present evidence that the disease was caused by Borrelia burgdorferi. In one of the cases Borrelia burgdorferi was repeatedly isolated from skin and subcutaneous tissue biopsies in spite of repeated high-dose therapy with ceftriaxone, Doxycycline and cefotaxime.

Adult↗