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Biomedical subjects

S A Machtens

Publications and source records attributed to S A Machtens.

7 recordsLinked to original sources
PubMed2006

Tissue microarrays: applications in urological cancer research.

Tissue microarrays (TMAs) are used to simultaneously study the expression of proteins in hundreds of tissue samples, offering the important advantage to screen large tissue banks for biomarker expression and to simultaneously examine serial sections obtained from the same tumor specimen by a time- and cost-effective analytical approach. This review article presents an overview of the importance and the impact of this technique in cancer research with increasing number of investigations using TMAs in its eighth anniversary. Its application, limitations, and selected previous study results regarding urologic malignancies are presented and discussed.

Biomarkers, Tumor↗
PubMed2001

Immunocytochemical distribution of nitric oxide synthase in the human corpus cavernosum: an electron microscopical study using the tyramide signal amplification technique.

Nitric oxide has proven to be an important mediator in the relaxation of human cavernosal smooth muscle. Nevertheless, there are many inconsistencies in the literature regarding the cellular and subcellular distribution of endothelial nitric oxide synthase in the human penis. The purpose of this study was to reexamine the localization of eNOS and nNOS in the cellular anatomy of the human cavernous body by means of electron microscopical immunocytochemistry in combination with the tyramide signal amplification technique (TSA). Using specific antibodies against eNOS and nNOS, the NAPDH-diaphorase reaction and advanced protocols for fixation and staining procederes, the occurrence of NOS isoenzymes eNOS and nNOS were examined in cavernosal specimens of ten male patients who were subjected to surgery for penile deviation. eNOS immunoreactivity and NADPH-d staining was seen to be significantly present in the endothelial cells covering the cavernous spaces and in the endothelium of helicine arteries. In endothelial cells, the NADPH-d reaction product BSPT-formazan was abundantly detectable attached to membranes of the endoplasmatic reticulum and the mitochondria whereas posititve eNOS immunostaining was seen in the endothelial cells throughout their cytoplasm without any particular relation to organelles. No considerable eNOS immunoreactivity was detectable in the trabecular smooth muscle cells. nNOS staining was found in nerve fibers innervating the cavernous body and cavernosal arteries. Our results counteract the hypothesis of the cavernous smooth muscle as a local source of NO and underline the importance of an intact endothelial function for penile erection and the contribution of eNOS to this process.

Biotin↗
PubMed2000

Pilot study of the transdermal application of testosterone gel to the penile skin for the treatment of hypogonadotropic men with erectile dysfunction.

Androgens influence important central and peripheral mechanisms of the erectile system. The relevance of a moderate decrease of serum testosterone level for erectile dysfunction (ED) has not been clarified so far. The aim of our study was to offer an easy transcutaneous method of androgen application. A previous study on the pharmacokinetic profile of the testosterone gel applied, showed marked elevation of the serum levels of testosterone. In our study, 46 hypogonadal patients with ED and total lack of vaginal penetration applied testosterone gel (4 mg/day; supplied by Azupharma, Germany) to the penile skin twice a day over 6-8 weeks, after a run-in period with placebo gel of 2 weeks. All patients showed decreased testosterone serum levels (<3 ng/ml) in at least two morning samples over a period of 3 weeks before treatment. Psychogenic etiology was excluded by a sexual psychologist. Patient age was 37-69 years (mean 53.5). Three patients (6.5%) responded to placebo in the run-in phase and were withdrawn from further treatment. Fifteen patients (32.6%) showed improved erection, allowing penetration and sexual intercourse. Twenty-eight patients (60.9%) did not respond to therapy. Local genital skin irritation was not observed. Elevation of peripheral testosterone was not correlated to a positive therapy response. A success-rate of 32.6% in this group of patients after exclusion of psychogenic patients and placebo-responders seems to justify further investigations. A medication period of 6-8 weeks is most probably too short to induce imaginable regenerative effects of testosterone on the erectile system. We therefore suggest that future double-blind and placebo-controlled studies should be designed for a minimum of 3 months. Testosterone gel may be a cost effective form of androgen administration.

Administration, Cutaneous↗
PubMed1997

Corpus cavernosum electromyography: technique and clinical implications.

Recently, corpus cavernosum EMG (CC-EMG) has been introduced into the diagnostic evaluation of erectile dysfunction. It has been demonstrated that CC-EMG may be a valuable tool in the evaluation of the integrity of the autonomic innervation of the corpus cavernosum. The interpretation and comparison of the recorded data still remains problematic due to a lack of standardization of recording procedures, technical equipment and of data analysis software. The assessment of recorded data was originally performed visually and nonquantitatively, however, more recently, computer-aided analysis of digitized measurements has proved to be more objective, less time-consuming and more reliable. Future efforts should be aimed at creating larger databases and differentiating between the various sources of lesions within the autonomic neural network of the corpus cavernosum.

Electromyography↗