Increased diurnal plasma concentrations of dehydroepiandrosterone in depressed patients

Activation of the hypothalamus-pituitary-adrenocortical system is a biological core symptom of depression. Although the regulation of cortisol secretion is well studied in this condition, there is no information about the diurnal activity of dehydroepiandrosterone (DHEA) secretion. Therefore, we studied 24-h DHEA plasma concentrations (every 30 min) in severely depressed patients (n = 26) and healthy controls (n = 33). We found depression to significantly increase diurnal minimal and mean DHEA plasma concentrations, whereas there was no effect on the diurnal maximal plasma concentration and the diurnal amplitude of DHEA. In particular, we found a parallel increase in mean DHEA (5.8 +/- 3.6 vs. 3.4 +/- 1.9 nmol/L; P < 0.003), cortisol (286 +/- 65 vs. 184 +/- 29 nmol/L; P < 0.0001) and ACTH (7.14 +/- 2.06 vs. 5.72 +/- 1.36 pmol/L; P < 0.002) plasma concentrations. The novel finding of parallel increases in diurnal DHEA and cortisol plasma concentrations in depressed patients has important implications for the regulation of the hypothalamus-pituitary-adrenocortical system in conditions of chronic stress and for the rationale of DHEA treatment in depressed patients.     

7 alpha-Biotinylated testosterone derivatives as tracers for a competitive chemiluminescence immunoassay of testosterone in serum

Ring core-biotinylated testosterone tracers were synthesized with bridges of three different lengths connecting the biotin moiety to the steroid core (7 alpha-Cn-Bio-T, n = 3, 6, or 11). Together with a position 7-specific polyclonal anti-testosterone antibody, we used the 7 alpha-C11-Bio-T tracer to develop a novel, labeled-hapten competitive immunoassay for total testosterone in serum. (The C3 and C6 tracers proved to be not suitable for analogous immunoassays.) Enhanced chemiluminescence signal was generated by use of a second immobilized antibody and a streptavidin-horseradish peroxidase conjugate. The measuring range of the assay is 0.2-20.0 nmol/L, linearity of serial dilutions can be demonstrated, the lower detection limit is 0.125 nmol/L, and the interassay imprecisions are 13-16%. Accuracy determinations in mass spectrometry-controlled reference specimens showed a mean recovery of 95%. In addition, the assay shows low cross-reactivities, demonstrating the favorable specificity of the combination of a "nearly native" tracer with a position analog antibody. The optimized steric structure and the long spacer arm of the biotinylated testosterone tracer make this chemiluminescence assay well-suited for measuring total testosterone concentration in serum.     

Photokatalytische Aktivierung von molekularem Sauerstoff mittels Eisen(III)porphyrin‐Komplexen

Photochemical charge transfer excitation of tetra‐phenyl(porphyrinato)iron(III) complexes yields tetraphenyl) (porphyrinato)iron(II) which is able to coordinate molecular oxygen under formation of oxo‐[tetraphenyl(porphyrinato)]‐ iron(IV). Based on this photochemical reaction pathway photocatalytic oxygenation of α‐pinene and other alkenes can be initiated. Iron(III) complexes of tetramesitylporphyrin, tetrakis‐(pentafluorophenyl)porphyrin, octa‐β‐bromo‐tetrakis‐(pentafluorophenyl)porphyrin, and octa‐β‐chloro‐tetrakis‐(pentafluorophenyl)porphyrin were investigated photochemically with the aim to improve the low photochemical efficiency of tetraphenyl(porphyrinato)iron(III). The influence of substituents on the porphyrin ligand on the photochemical behavior of the corresponding iron(III) complexes is measured mainly by means of temperature dependent UV/Vis spectroscopy. Both, the yield of oxygenation products formed photocatalytically with α‐pinene and the product distribution (allylic alcohols versus epoxide) depend on the design of the porphyrin ligands coordinated with iron(III).     

The multiple forms of brain acetylcholinesterase. I. Micro-electrophoresis and topochemical analysis of the pattern

Micro-polyacrylamide gradient electrophoresis followed by active staining is applied for the demonstration of the multiple forms of acetylcholinesterase. Among other advantages the very small samples that enable the analysis of well-defined brain material as well as the almost histochemical conditions of incubation enable its successful use in topochemical investigations of the multiple form pattern of brain acetylcholinesterase. The acetylcholinesterase of bovine nc. caudatus could be separated into 4 multiple forms and the pattern was analysed microdensitometrically. These forms differ in their molecular weight as well as in their degree of membrane binding. Increasing ionic strength (NaCl) is followed by changes in the pattern. This result is discussed as caused by aggregation of enzyme subunits.     

Pre-evaluation and system optimization of the Elecsys thyroid electrochemiluminescence immunoassays

Aortic atherosclerosis has early been recognized as a potential source of embolism. The histological finding of cholesterol clefts in small end-arteries characterized the entity of cholesterol embolism. The clinical picture was extremely variable and the diagnosis was frequently established post-mortem or by means of invasive although insensitive procedures including biopsy and angiography. Therefore, cholesterol embolism was thought to be rare. With the routine use of transesophageal echocardiography for the diagnostic workup of arterial embolism, aortic atherosclerosis was shown to be the source of otherwise unexplainable embolism. Cross-sectional studies demonstrated an independent association between prominent plaques of more than 4 to 5 mm of thickness or plaques with mobile components in the aortic arch. In follow-up studies, the risk of embolic events in patients with this kind of lesions exceeded 10% per patient-year. The results of pathological studies were consistent with these findings showing that ulcerated complex plaques carry an independent risk for embolic events. Apart from spontaneous embolism, atherosclerosis of the proximal aorta was shown to be a cause of embolic complications during cardiac surgery and catheterization procedures which involve the aorta. Medical treatment for the prevention of embolism in atherosclerotic disease of the aorta has not been studied systematically. In a variant form of aortic atherosclerosis consisting of mobile pedunculated thrombi inserting on relatively small plaques, anticoagulant therapy has proved to be useful in small numbers of patients. Recurrent embolic events could be prevented and regression of the thrombotic masses has been observed.