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Biomedical subjects

Christian Roth

Publications and source records attributed to Christian Roth.

22 records · Page 2Linked to original sources
PubMed2003

Obesity in patients with craniopharyngioma: assessment of food intake and movement counts indicating physical activity.

Patients with childhood-onset craniopharyngioma (CP) often suffer from obesity. We evaluated two important etiological factors of obesity development, energy intake and physical activity. Energy intake was supposed to be high due to a disturbed hypothalamic regulation of appetite. We used a validated nutritional diary to determine the 1-wk food intake in 27 CP patients (12 with intrasellar tumors and 15 with hypothalamic tumors) and 1027 controls who were a representative sample of the 7- to 16-yr-old German population. In 2 accelerometry settings, we determined movement counts indicating physical activity. Nineteen CP patients were comparable to 26 controls for age and body mass index. One setting was a clinical one during weight reduction; the other was an out-patient setting. Daily energy intake was 1916 +/- 677 kcal (mean +/- SD) in intrasellar CP patients, 2075 +/- 877 kcal in hypothalamic CP patients, and 2476 +/- 815 kcal in non-CP controls. Patients suffering from CP showed fewer movement registrations [clinical setting, 228 vs. 298 cpm for obese controls (P = 0.01); out-patient setting, 228 vs. 282 cpm for controls (P = 0.08)]. Differences were most pronounced during leisure time (382 cpm in CP patients vs. 546 cpm in obese controls; P = 0.002; clinical setting). Our findings suggest that reduced physical activity, rather than increased energy intake, in CP patients is responsible for the obesity development noted in these subjects.

Adolescent↗
PubMed2002

Rubredoxins involved in alkane oxidation.

Rubredoxins (Rds) are essential electron transfer components of bacterial membrane-bound alkane hydroxylase systems. Several Rd genes associated with alkane hydroxylase or Rd reductase genes were cloned from gram-positive and gram-negative organisms able to grow on n-alkanes (Alk-Rds). Complementation tests in an Escherichia coli recombinant containing all Pseudomonas putida GPo1 genes necessary for growth on alkanes except Rd 2 (AlkG) and sequence comparisons showed that the Alk-Rds can be divided in AlkG1- and AlkG2-type Rds. All alkane-degrading strains contain AlkG2-type Rds, which are able to replace the GPo1 Rd 2 in n-octane hydroxylation. Most strains also contain AlkG1-type Rds, which do not complement the deletion mutant but are highly conserved among gram-positive and gram-negative bacteria. Common to most Rds are the two iron-binding CXXCG motifs. All Alk-Rds possess four negatively charged residues that are not conserved in other Rds. The AlkG1-type Rds can be distinguished from the AlkG2-type Rds by the insertion of an arginine downstream of the second CXXCG motif. In addition, the glycines in the two CXXCG motifs are usually replaced by other amino acids. Mutagenesis of residues conserved in either the AlkG1- or the AlkG2-type Rds, but not between both types, shows that AlkG1 is unable to transfer electrons to the alkane hydroxylase mainly due to the insertion of the arginine, whereas the exchange of the glycines in the two CXXCG motifs only has a limited effect.

Alkanes↗
PubMed2002

Therapeutic potential of GnRH antagonists in the treatment of precocious puberty.

Pituitary-gonadal axis activation depends upon pulsatile hypothalamic gonadotropin-releasing hormone (GnRH) secretion. This phenomenon has led to clinical use of GnRH agonists in the treatment of central precocious puberty. GnRH analogues contain substitutions of the native decapeptide. Depending upon the substitutions, the analogues have GnRH agonistic or antagonistic properties. The pharmacokinetics of GnRH agonists, the established treatment of precocious puberty, includes an initial 'flare-up' of the pituitary-gonadal axis, followed by a reduced luteinising hormone secretion by desensitisation of pituitary GnRH receptors. Antagonistic GnRH analogues act by competitive binding to the pituitary GnRH receptors, thereby preventing the action of endogenous GnRH - theoretically offering a more direct and dose-dependent treatment alternative. The antagonist available today in Germany is a concomitant in assisted reproduction with only 1 - 3 days duration. However, long-acting depot preparations of other GnRH antagonists are in primate-testing phase. Our animal tests indicate strong potential for the development and testing of long-acting depot preparations of GnRH antagonists in treating precocious puberty.

Animals↗