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Biomedical subjects

Thomas Jansen

Publications and source records attributed to Thomas Jansen.

At least 19 recordsLinked to original sources
PubMed2007

CYP2R1-, CYP27B1- and CYP24-mRNA expression in German type 1 diabetes patients.

1,25(OH)(2)D(3) and 25(OH)D(3) have been associated with type 1 diabetes. Diverse enzymes are involved in the synthesis of these metabolites: the 25-Vitamin-D-hydroxylase (CYP2R1), the 25-hydroxyvitamin-D(3)-1-alpha-hydroxylase (CYP27B1) and the 25(OH)D(3)-24-hydroxylase (CYP24) among others. Serum levels of 25(OH)D(3) and 1,25(OH)(2)D(3) were investigated in type 1 diabetes patients (n=173) and the mRNA expression of the CYP2R1, CYP27B1 and CYP24 genes in type 1 diabetes patients (n=33) and healthy controls (n=23). These parameters were correlated with the -1260 (C/A) polymorphism in the CYP27B1 gene. Lower expression of CYP27B1 mRNA in comparison with healthy controls (1.7165 versus 1.7815, P=0.0268) was found. Additionally, patients carrying the genotype CC possessed a reduced amount of CYP27B1 mRNA compared to healthy controls (1.6855 versus 1.8107, respectively, P=0.0220). The heterozygosity rate of the -1260 C/A polymorphism was more frequent in patients with normal levels of 1,25(OH)(2)D(3) (> or =19.9 pmol/ml) than in whose with a level of less than 19.9 pmol/ml (46.7% versus 22.2%, P=0.0134). No correlation with serum levels of 25(OH)D(3) was found. Thus, CYP27B1 gene could play a functional role in the pathogenesis of type 1 diabetes through modulation of its mRNA expression and influence serum levels of 1,25(OH)(2)D(3) via the -1260 C/A polymorphism.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2006

Active breathing control (ABC): determination and reduction of breathing-induced organ motion in the chest.

PURPOSE: Extensive radiotherapy volumes for tumors of the chest are partly caused by interfractional organ motion. We evaluated the feasibility of respiratory observation tools using the active breathing control (ABC) system and the effect on breathing cycle regularity and reproducibility. METHODS AND MATERIALS: Thirty-six patients with unresectable tumors of the chest were selected for evaluation of the ABC system. Computed tomography scans were performed at various respiratory phases starting at the same couch position without patient movement. Threshold levels were set at minimum and maximum volume during normal breathing cycles and at a volume defined as shallow breathing, reflecting the subjective maximal tolerable reduction of breath volume. To evaluate the extent of organ movement, 13 landmarks were considering using commercial software for image coregistration. In 4 patients, second examinations were performed during therapy. RESULTS: Investigating the differences in a normal breathing cycle versus shallow breathing, a statistically significant reduction of respiratory motion in the upper, middle, and lower regions of the chest could be detected, representing potential movement reduction achieved through reduced breath volume. Evaluating interfraction reproducibility, the mean displacement ranged between 0.24 mm (chest wall/tracheal bifurcation) to 3.5 mm (diaphragm) for expiration and shallow breathing and 0.24 mm (chest wall) to 5.25 mm (diaphragm) for normal inspiration. CONCLUSIONS: By modifying regularity of the respiratory cycle through reduction of breath volume, a significant and reproducible reduction of chest and diaphragm motion is possible, enabling reduction of treatment planning margins.

Adult↗
PubMed2006

Angiokeratoma circumscriptum arranged in a systematized band-like pattern suggesting mosaicism.

A 10-year-old girl with vascular lesions that had been present since birth is reported. Initially, small red macules were limited to the legs, but later the lesions became more extensive. A hyperkeratotic aspect of the lesional skin surface had developed at the age of 2 years. On clinical examination, hyperkeratotic vascular lesions in a band-like distribution on the trunk, legs and face were observed. The type of lesion varied from discrete macules with no or slight hyperkeratosis to confluent, protruding verrucous plaques. The clinical and histopathological findings were consistent with a diagnosis of angiokeratoma circumscriptum. The systematized band-like arrangement observed in the present case strongly supports the concept that angiokeratoma circumscriptum reflects a mosaic state of a mutation that is so far unknown.

Angiokeratoma↗
PubMed2006

Axillary acne agminata (lupus miliaris disseminatus faciei with axillary involvement).

Acne agminata (AA) and lupus miliaris disseminatus faciei (LMDF) have been used to describe very similar clinical conditions and it is now generally accepted that they are synonymous. The cause of these disorders has not been determined. Clinically the disease presents with often agminated redbrown to yellow papules which occasionally become pustular. Microscopically, superficial granulomatous inflammation with perifollicular caseating granulomas is the hallmark. Axillary involvement with LMDF has rarely been reported; in this area AA has been the preferred term. When only the axillae are affected, it may be difficult to distinguish acne agminata from other granulomatous diseases, especially from granulomas caused by antiperspirants containing aluminumzirconium complexes. We describe a 36-year-old woman with axillary acne agminata.

Acneiform Eruptions↗
PubMed2006

Protection from type 1 diabetes by vitamin D receptor haplotypes.

Vitamin D has been involved in the modulation of calcium and bone metabolism as well as in the immune system, where it suppresses the proliferation of activated T cells. These effects are exerted via the vitamin D receptor (VDR). Polymorphisms within this gene have been exhaustively studied in diverse autoimmune diseases but with inconsistent results. We previously reported a positive association of polymorphisms within the VDR gene (Apa I, Taq I, Bsm I, and Fok I). In the present article we extended our previous reports to seven additional polymorphisms (rs757343, rs9729, rs2853559, rs1989969, rs3847987, rs2238135, and rs4516035) in a larger set of German simplex type 1 diabetes families. Additionally we correlated serum levels of 25(OH)D(3) and 1,25(OH)(2)D(3) with VDR genotypes and haplotypes. The haplotypes "CG" (Taq I-Apa I), "CGG" (Taq I-Apa I-Tru I), "CGC" (Taq I-Apa I-Fok I), "GCTG" (rs9729-Taq I-Apa I-Tru I), and "CGGC"(Taq I-Apa I, Tru I, Fok I) were less often transmitted, thus negatively associated with type 1 diabetes. Patients who carried the genotype "CC" of the rs3847987 polymorphism had higher median serum levels of 25(OH)D(3). Furthermore, the majority of patients with this genotype possessed normal serum levels of 25(OH)D(3). We conclude that variants of the VDR may confer a genetic protection from type 1 diabetes. Furthermore, normal serum levels of 25(OH)D(3) appear to correlate with a VDR genotype. This supports a role of vitamin D in the immune pathogenesis of type 1 diabetes.

Calcifediol↗
PubMed2005

On the choice of the offspring population size in evolutionary algorithms.

Evolutionary algorithms (EAs) generally come with a large number of parameters that have to be set before the algorithm can be used. Finding appropriate settings is a difficult task. The influence of these parameters on the efficiency of the search performed by an evolutionary algorithm can be very high. But there is still a lack of theoretically justified guidelines to help the practitioner find good values for these parameters. One such parameter is the offspring population size. Using a simplified but still realistic evolutionary algorithm, a thorough analysis of the effects of the offspring population size is presented. The result is a much better understanding of the role of offspring population size in an EA and suggests a simple way to dynamically adapt this parameter when necessary.

Algorithms↗
PubMed2004

Unilateral angiokeratoma scroti: a rare manifestation of a vascular tumor.

A 21-year-old patient with a six-year history of asymptomatic papular lesions on his scrotum is reported. The lesions were limited to one half of the scrotum and associated with subclinical varicocele on the same side. The clinical and histopathological findings were consistent with a diagnosis of angiokeratoma scroti. Increased venous pressure caused by the varicocele may have been responsible for the unilateral development of angiokeratoma in this patient.

Adult↗
PubMed2004

Morbihan's disease: treatment with CO2 laser blepharoplasty.

Morbihan's disease is a rare condition characterized by chronic persistent erythema and edema of the upper half of the face. Therapeutic regimens such as X-ray irradiation, lymphatic massage, interferon gamma injections, antihistamines, and high-dose antibiotics are often unsatisfactory. Promising results in some patients have been achieved by a systemic combination therapy of isotretinoin with ketotifen or clofazimine. Excision of redundant edematous tissue may be an alternative. We present a 67-year-old Caucasian patient with a two-year history of right lower and upper eyelid swelling and erythema. Systemic therapies with corticocosteroids and antibiotics were not successful, but CO2 laser blepharoplasty led to good cosmetic results with marked improvement of visual impairment and no recurrence during the six-month follow-up period.

Aged↗