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Biomedical subjects

A Martens

Publications and source records attributed to A Martens.

At least 19 recordsLinked to original sources
PubMed2003

[Diagnosis of cystic fibrosis; simple genotyping to rule out the disease preferable to starting with the sweat test].

For historical reasons, the sweat test remains the cornerstone in the diagnostic work-up for cystic fibrosis (CF). If CF is suspected, the sweat test (following pilocarpine iontophoresis) is usually performed first to confirm or rule out the diagnosis of CF. Sweat testing, however, is cumbersome to the patient, prone to technical difficulties and unreliable in young children < 4 weeks as well as in adults because of increasing chloride concentrations with age. False-positive and false-negative results do exist. Simple DNA testing with PCR in peripheral blood for a small number of the most common mutations causing CF, notably the delta F508-mutation in the Dutch population, rules out CF with a likelihood of more than 99%. Because of the high negative predictive value of DNA testing, in combination with its speed, reliability and convenience for the patient, starting the diagnostic work-up for CF with DNA testing can be justified in hospitals which possess the laboratory facilities for this type of test.

Cystic Fibrosis↗
PubMed2001

Evaluation of excision, cryosurgery and local BCG vaccination for the treatment of equine sarcoids.

Ninety-five horses with sarcoids were subjected to three types of treatment: surgical excision (conventional or carbon dioxide laser), cryotherapy or local BCG vaccination. The type of treatment was selected on the basis of the size, location and clinical appearance of the tumours. The choice between conventional and laser excision was empirical. A successful outcome was obtained in 11 of 14 (79 per cent) of the horses treated by cryosurgery, 18 of 27 (67 per cent) treated by BCG vaccination, 18 of 22 (82 per cent) treated by conventional excision, and 20 of 28 (71 per cent) treated with a carbon dioxide laser. For both excision methods, rigorous measures were taken to avoid autoinoculation and to ensure a wide margin of normal skin. The probability of local recurrence after excision was significantly higher for large sarcoids and sarcoids which had previously failed to respond to treatment. In 10 of the 31 horses with remaining sarcoids, some or all of the untreated sarcoids were observed to regress spontaneously.

Animals↗
PubMed2001

PCR detection of bovine papilloma virus DNA in superficial swabs and scrapings from equine sarcoids.

The purpose of this study was to examine if bovine papilloma virus (BPV) DNA can be detected in superficial swabs or scrapings from equine sarcoids. Samples were obtained from 92 sarcoids and 20 non-sarcoidal control lesions. The polymerase chain reaction technique was used with a first primer set to check whether DNA extraction was successful, and with a second primer set specific for BPV-DNA. DNA isolation was successful in 88% of the swabs and 93% of the scrapings. All control lesions were negative for BPV-DNA.

Animals↗
PubMed2001

Ancient diversification of the Pto kinase family preceded speciation in Solanum.

Recent phylogenetic analyses of the nucleotide binding sites (NBS)-leucine-rich repeats (LRR) class of plant disease resistance (R) genes suggest that these genes are ancient and coexist next to susceptibility alleles at resistance loci. Another class of R genes encodes serine-threonine protein kinases related to Pto that were originally identified from wild relatives of tomato. In this study, we exploit the highly diverse genus Solanum to identify Pto-like sequences and test various evolutionary scenarios for Pto-like genes. Polymerase chain reaction amplifications with the use of primers that were developed on the basis of conserved and variable regions of Pto revealed an extensive Pto gene family and yielded 32 intact Pto-like sequences from six Solanum species. Furthermore, Pto-like transcripts were detected in the leaf tissue of all tested plants. The kinase consensus and autophosphorylation sites were highly conserved, in contrast to the kinase activation domain, which is involved in ligand recognition in Pto. Phylogenetic analyses distinguished nine classes of Pto-like genes and revealed that orthologs were more similar than paralogs, suggesting that the Pto gene family evolved through a series of ancient gene duplication events prior to speciation in Solanum. Thus, like the NBS-LRR class, the kinase class of R genes is highly diverse and ancient.

Amino Acid Sequence↗
PubMed2001

"Docs 'n drugs--the virtual polyclinic": an intelligent tutoring system for web-based and case-oriented training in medicine.

Since the beginning of the year 2000 medical students of the University of Ulm are working in their curriculum with the web-based and case-oriented tutoring system "Docs 'n Drugs - The Virtual Polyclinic". The system consists of different subsystems and services. One subsystem is the Training System. It is based on three models: the Tutoring Process Model, the Case Knowledge Model and the Medical Knowledge Model. They describe the tutoring process as a series of nodes and steps, depict the structure of the medical cases, and provide the medical knowledge respectively. Case knowledge and medical knowledge form the expert knowledge of the medical domain. Together with the tutoring process, they build the basis for automatic intelligent tutoring. After giving a deeper insight into the system architecture and the training case structure, an informal evaluation shows a first feedback of the learners.

Clinical Medicine↗
PubMed2000

Partial tibial neurectomy in 113 Belgian blue calves with spastic paresis.

One hundred and thirteen double-muscled Belgian blue calves (69 males and 44 females) with spastic paresis (52 unilateral and 61 bilateral) were treated surgically by partial tibial neurectomy under caudal epidural anaesthesia. Telephone inquiries made at least three-and-a-half months later established that good results were obtained in 83.2 per cent of the calves; a considerable improvement was reported in 4.4 per cent which still had intermittent spastic contractions; severe hyperflexion of the hock necessitating early slaughtering was recorded in 4.4 per cent of the calves; and in 8 per cent there was little or no improvement.

Anesthesia, Epidural↗
PubMed2000

Histopathological characteristics of five clinical types of equine sarcoid.

The purpose of this study was to determine the characteristics of occult, verrucous, fibroblastic, nodular and mixed equine sarcoids. Ten tumours of each type were examined histologically and analysed for the presence of bovine papilloma virus (BPV)- DNA. All tumours were positive for BPV - DNA and showed an increased density of dermal fibroblasts. Epidermal hyperplasia, hyperkeratosis, rete peg and 'picket fence' formation were only found consistently in the verrucous and mixed types and were often not present in occult and nodular sarcoids. Immunohistochemical staining for Keratins 10 and 16, Ki67 and p53 showed no important differences between the clinical types. It can be concluded that the presence of BPV - DNA and the increased density of dermal fibroblasts were the only common characteristics for all sarcoids of the different clinical types. The presence of other microscopic alterations was variable but could not be used in the differentiation of the clinical types based on histology.

Animals↗
PubMed2000

In vitro and in vivo evaluation of hypericin for photodynamic therapy of equine sarcoids.

The therapeutic potential of the photodynamic compound, hypericin, in the treatment of equine sarcoids was evaluated. The in vitro cytotoxicity was assessed using three equine cell lines and the observed phototoxic effect was comparable to that on different highly sensitive human cell lines and significantly influenced by the energy density used although independent of the cell type. The in vivo antitumoural action of photodynamic therapy using hypericin was evaluated on three equine sarcoids in a donkey. Four intratumoural injections were given and the tumours were illuminated daily during 25 days. An 81% reduction in tumour volume was obtained at the end of therapy and 2 months later, a 90% reduction was observed. Further experimental work should be performed, but these results suggest that photodynamic therapy using hypericin has a potential for the non-invasive treatment of equine sarcoids.

Animals↗
PubMed2000

A flexible architecture for constructing and executing tutoring processes.

The tutoring process of conventional case-oriented medical training systems can be characterised as either guided or unguided. In contrast to that, the aim of the system "Docs'n Drugs" is to distinguish between different levels of guidance. The author can realise the tutoring case as a guided, a half guided or an unguided tutoring process. The system architecture distinguishes between an authoring system and a tutoring system. Fundaments of these are the tutoring process model and the case data model. This structure allows the reuse of elements of existing tutoring cases. The tutoring cases can be realised in different languages, e.g. German and English.

Computer-Assisted Instruction↗
PubMed1999

Reverse chromosome painting for the identification of marker chromosomes and complex translocations in leukemia.

BACKGROUND: Chromosome banding techniques and in situ hybridization reveal the majority of chromosomal aberrations. However, difficulties remain in cases of highly contracted chromosomes, poor quality of the metaphases or the presence of markers with the involvement of several chromosomes. Here, it is demonstrated that reverse painting can be applied successfully starting with bone marrow cells from primary acute myelocytic leukemias (AML). METHODS: This was accomplished by culturing the leukemic cells with a cocktail of various growth factors, which yielded sufficient numbers of cells in cycle to harvest chromosomes for sorting. Aberrant chromosomes were flow-sorted and amplified by degenerate oligonucleotide-primed PCR. The resulting products were labeled by nick-translation and hybridized on normal metaphase spreads. RESULTS: Two patients with marker chromosomes in their leukemia cells were analyzed in detail. The hybridization pattern displayed the composition of the aberrant sorted chromosome. Results were compared with conventional cytogenetic analyses that were performed on material obtained from the same aspirate. The reverse-painting technique enabled identification of aberrations that were not detected by conventional cytogenetic analysis. CONCLUSIONS: Primary AML cells can be cultured in vitro, using optimal culture conditions, facilitating the production of high quality flow karyotypes, suitable for sorting of marker chromosomes to produce DOP-PCR derived chromosome painting probes for reverse painting. Valuable additional cytogenetic information can thus be obtained about complex chromosomal rearrangements or structural aberrations that could not be completely resolved by conventional cytogenetic analysis.

Bone Marrow↗
PubMed1999

Neutrophil function capacity to express CD10 is decreased in patients with septic shock.

OBJECTIVE: To evaluate the performance of a newly developed assay to assess neutrophil function capacity. After optimization, the assay was performed on samples derived from patients with septic shock and compared with healthy controls and patients with a systemic viral infection. DESIGN: Prospective evaluation of the performance of a new assay. SETTINGS: Medical intensive care unit, hospital laboratory. PATIENTS: Ten patients with septic shock, ten patients with infectious mononucleosis, and ten healthy controls. MEASUREMENTS AND MAIN RESULTS: We report an assay to assess neutrophil function capacity, in which CD10 membrane expression is measured by FACS before and after in vitro stimulation with Staphylococcus aureus bacteria. This assay evaluates the early activation state of circulating neutrophils and is shown to be of value in diagnosing a sepsis syndrome. First the assay was optimized. As an anticoagulant, sodium-citrate gave the best results. Blood samples must be kept on ice to reduce activation inside the siliconized tube and can be stored in this way for at least 8 hrs without affecting the test results. Kinetic studies showed a maximal expression of CD10 on neutrophils of healthy volunteers after 15 mins of stimulation with S. aureus bacteria. Second, the test was performed on samples derived from ten septic patients and ten patients with infectious mononucleosis. Septic patients had a significantly decreased CD10 expression capacity compared with healthy controls. Patients with infectious mononucleosis have a significantly higher CD10 expression capacity compared with septic patients, but in approximately one-half of them, the expression capacity was below the range found in controls. CONCLUSIONS: These results indicate that in circulating neutrophils, the secretory vesicles have been mobilized completely in patients with septic shock. The assay proves to be of acceptable analytical quality and can be quickly and easily performed. Regarding clinical performance, this assay may be helpful in diagnosing septic shock.

Adolescent↗
PubMed1999

Effects of nabumetone compared with naproxen on platelet aggregation in patients with rheumatoid arthritis.

OBJECTIVE: To test the hypothesis that nabumetone (a partially selective cyclooxygenase-(COX)-2 inhibitor) has less effect on platelet aggregation than naproxen (a non-selective COX-inhibitor) in patients with rheumatoid arthritis (RA). METHODS: A crossover study in 10 RA patients was performed, using either nabumetone or naproxen for two weeks, and, after a washout period of two weeks, the other drug during another two weeks. Platelet aggregation studies were performed and bleeding time was assessed before and after each treatment period. RESULTS: Maximum platelet aggregation induced by epinephrine and by collagen was significantly more reduced after the use of naproxen than of nabumetone; secondary aggregation induced by ADP and epinephrine disappeared more often by naproxen than by nabumetone. Bleeding times were not influenced. CONCLUSION: COX dependent platelet aggregation in RA patients seems to be more inhibited by naproxen than by nabumetone. This may be relevant for patients requiring non-steroidal anti-inflammatory drug treatment but who have an increased risk of bleeding as well.

Adolescent↗
PubMed1998

Constitutive internalization and association with adaptor protein-2 of the interleukin-6 signal transducer gp130.

The transmembrane protein gp130 is the common signalling receptor subunit for the interleukin-6 (IL-6)-type cytokines. It has recently been shown that the cytoplasmic domain of gp130 contains a dileucine internalization motif and that endocytosis of gp130 occurs signal-independent. Here, we have studied whether gp130 itself undergoes constitutive internalization or whether its endocytosis is stimulated by formation of the IL-6/IL-6R/gp130 complex. Using two different assays, we found that gp130 is internalized independent from IL-6/IL-6R stimulation. In addition, we show that gp130 is constitutively associated with the cell surface adaptor complex AP-2. Our findings strongly suggest endocytosis of gp130 to be constitutive.

Adaptor Protein Complex alpha Subunits↗
PubMed1998

Soluble IL-6 receptor potentiates the antagonistic activity of soluble gp130 on IL-6 responses.

Soluble receptors for several cytokines have been detected in body fluids and are believed to modulate the cytokine response by binding the ligand and thereby reducing its bioavailability. In the case of IL-6, the situation is more complex. The receptor consists of two components, including a ligand-binding alpha-subunit (IL-6R, gp80, or CD126), which in its soluble (s) form (sIL-6R) acts agonistically by making the ligand accessible to the second subunit, the signal transducer gp130 (CD130). Soluble forms of both receptor subunits are present in human blood. Gel filtration of iodinated IL-6 that had been incubated with human serum revealed that IL-6 is partially trapped in IL-6/sIL-6R/sgp130 ternary complexes. sgp130 from human plasma was enriched by immunoaffinity chromatography and identified as a 100-kDa protein. Functionally equivalent rsgp130 was produced in baculovirus-infected insect cells to study its antagonistic potential on four different cell types. It was found that in situations in which cells lacking membrane-bound IL-6R were stimulated with IL-6/sIL-6R complexes, sgp130 was a much more potent antagonist than it was on IL-6R-positive cells stimulated with IL-6 alone. In the latter case, the neutralizing activity of sgp130 could be markedly enhanced by addition of sIL-6R. As a consequence of these findings, sIL-6R of human plasma must be regarded as an antagonistic molecule that enhances the inhibitory activity of sgp130. Furthermore, in combination with sIL-6R, sgp130 is a promising candidate for the development of IL-6 antagonists.

Adjuvants, Immunologic↗
PubMed1998

Conservative and surgical treatment of tibial fractures in cattle.

Ninety-five cattle with tibial fractures, all but one with a unilateral fracture, were examined between 1990 and 1994. The feasibility of repairing the fracture was assessed radiographically, also taking into account the bodyweight and value of the animal. Twenty-two cattle were slaughtered. Conservative treatment with stall confinement and/or a splint or cast was applied in 18 cases, with satisfactory results in eight of them (44 per cent). They were fattened to normal bodyweight, but they all had a severe deformity of the affected leg. In 55 animals, the fractures were fixed externally with Steinmann pins and methylmethacrylate bridges under image-intensified fluoroscopy. Ten of them could not bear weight on the affected leg and were slaughtered before the pins were removed. In the remaining 45 animals the pins were removed after a mean (sd) period of 71 (14) days. Four animals re-fractured the affected leg shortly after the pins were removed and six others were slaughtered prematurely because of inadequate weight bearing. The results were successful in 35 cases (64 per cent). Slight deviations of the affected leg and/or the contralateral leg were often observed. The overall survival rate of the cattle with tibial fractures was 45 per cent.

Animals↗