Biomedical subjects

H Geyer

Publications and source records attributed to H Geyer.

At least 19 recordsLinked to original sources

PubMed2006

17beta-hydroxy-5alpha-androst-1-en-3-one (1-testosterone) is a potent androgen with anabolic properties.

Since the begining of the year 2005, the use of steroid precursors (prohormones) is illegal in the United States; nevertheless, there is still an enormous abuse of such substances. One of the most frequently misused steroids, often declared to be a prohormone, is 1-testosterone (17beta-hydroxy-5alpha-androst-1-en-3-one, 1-Testo). In this study, we have characterised molecular mechanisms of its action, determined its tissue specific androgenic and anabolic potency and investigated potential adverse effects. 1-Testo binds highly selective to the androgen receptor (AR) and has a high potency to stimulate AR dependent transactivation. In vivo an equimolar dose of 1-Testo has the same potency to stimulate the growth of the prostate, the seminal vesicles and the androgen sensitive levator ani muscle as the reference compound testosterone propionate (TP). Administration of 1-Testo, in contrast to TP, results in a significant increase of liver weight. Our results demonstrate that 1-Testo, even without being metabolised, is a very potent androgen. It binds selectively to the AR and transactivates AR dependent reporter genes. In vivo it has a high androgenic and anabolic potency and increases liver weight. In summary 1-Testo can be characterised as a typical anabolic steroid. It has to be assumed that consumption of this substance is associated with adverse side effects typical for this class of compounds. Therefore, a strict control of its ban is essential.

Anabolic Agents↗

PubMed2006

The content and composition of lipids in the digital cushion of the bovine claw with respect to age and location--a preliminary report.

The pads of the bovine digital cushion, which serves as a shock absorber, have specific anatomical structures to cope with the substantial forces acting within the claw. To gain more information on the lipid composition and content of the pads, horn shoes from 12 slaughtered heifers and cows were removed and different samples of the pads excised with a scalpel. Pad lipids were extracted and the fatty acid composition determined by gas chromatography. Fat from perirenal and subcutaneous adipose tissues served as a comparison. Overall, this fat contained a higher quantity of extracted lipids than that of the claw pads and did not differ between heifers and cows. In contrast, lipid content in the pads was significantly higher in the cows than in the heifers. In both groups, the lipid content of the middle and abaxial pads, which are situated directly under the distal phalanx, was lower than in the pads of the other locations. The lipids in all pads contained >77% monounsaturated fatty acids (MUFA), differing sharply from the adipose tissue with values <51%. Among the polyunsaturated fatty acids (PUFA) a significantly higher proportion of arachidonic acid (AA) was found in the heifer pads than in those of the cows, whereas the proportion of AA was similar in the adipose tissue of all animals. The proportion of AA in the pad lipids also varied between the defined locations with the highest proportion found in locations that showed the lowest lipid content and was related to the age of the animal.

Age Factors↗

PubMed2006

[Do hoof cracks represent a superficial hoof-problem?].

Fifty-four horses with hoof cracks were referred to the Equine Hospital of the University of Zurich, for treatment. The horses were admitted because of lameness or other symptoms caused by the cracks. Deep or complicated quarter cracks were the most common type of cracks diagnosed. Poor conformation and abnormal hoof shape were the most important causes of hoof crack development, whereas injury to the coronary band was a less frequently encountered cause. Effective treatment of this problem includes corrective shoeing, removing horn from the weight-bearing surface as well as from the crack with a Dremel tool and immobilization of the borders of the crack. However, even with such a therapy, the recurrence rate of hoof cracks was with 20% very high.

Animals↗

PubMed2006

[The art of horseshoeing--between empiricism and science].

To correctly shoe a horse requires the farriers to have a good working knowledge of postural anomalies and movement patterns, as well as of the different concepts of horseshoeing and to be able to apply the appropriate technique to every individual horse they shoe. The correct technique for specific problem cases is frequently a subject of debate amongst specialists and many theories would benefit from objective gait analyses. The case study presented examines the influence of different shoeing conditions on selected gait analysis parameters. The measurements were conducted on a Warmblood mare: (A) shod with long toes, (B) properly trimmed without shoes, (C) conventionally shod with rolled toes and finally (D) shod using the 4-point technique. Data on force-, time- and distance parameters were recorded using an instrumented treadmill. First contact and breakover of the hooves were documented using high-speed videography. A long toe resulted in a prolongation of the breakover time and, therefore, in a prolongation of the second half of the stance phase. Additionally, the prolonged stance duration associated with an unaltered force impulse, led to decreased force peaks. It was possible to objectively record differences between the trimmed, unshod foot, the shod long-toe and the shod rolled toe configurations. The differences between the rolled toe and the 4 point shoe however, were minimal. Gait analysis is a technique well suited for objective evaluation of different shoeing techniques under standardised conditions.

Animals↗

PubMed2006

[Do we need a quality control for horse shoes and farriery].

In the past few years marked changes in the field of farriery have been noted. In addition to the classical farrier, many new occupations concerned with hoof care have emerged, such as hoof trimmer, hoof technician, hoof orthopedist and hoof naturopath. Furthermore, a tremendous number of hoof protection systems have been developed, with an ever-increasing application to horses. However, regulations regarding alternative shoeing methods are insufficient and it is not clear, who governs the quality of the work of the individuals involved. Thus, a neutral authority composed of farriers and veterinarians should be formed to develop guidelines for the education of individuals involved with hoof care and for the distribution of various farriery products.

Animal Husbandry↗

PubMed2006

[Interactive educational DVD on hoof protection, horseshoeing and diseases of the hoof].

Good cooperation between farrier, veterinarian and horse owner is an important prerequisite for optimal support of the horse with regards to shoeing and hoof health. The introduction of a joint educational aid aims to improve the level of education of both veterinarians and farriers. The interactive, multimedia approach represents an innovative new dimension in instruction techniques, predominantly provided through images and videos. The contents of the new teaching aid will focus on detailed anatomy of the foot and distal limb, as well as currently accepted shoeing practices and techniques and pathologic conditions of the hoof and foot.

Animals↗

PubMed2006

Magnetic resonance imaging, ultrasonography and histology of the suspensory ligament origin: a comparative study of normal anatomy of warmblood horses.

REASONS FOR PERFORMING STUDY: The diagnosis of lameness caused by proximal metacarpal and metatarsal pain can be challenging. Magnetic resonance imaging (MRI) offers the possibility for further diagnosis but there have been no studies on the normal MRI appearance of the origin of the suspensory ligament (OSL) in conjunction with ultrasonography and histology. OBJECTIVES: To describe the MRI appearance of the OSL in fore- and hindlimbs of sound horses and compare it to the ultrasonographic and histological appearance. The findings can be used as reference values to recognise pathology in the OSL. METHODS: The OSL in the fore- and hindlimbs of 6 sound horses was examined by ultrasonography prior to death, and MRI and histology post mortem. Qualitative evaluation and morphometry of the OSL were performed and results of all modalities compared. RESULTS: Muscular tissue, artefacts, variable SL size and shape complicated ultrasonographic interpretation. In MRI and histology the forelimb OSL consisted of 2 portions, the lateral being significantly thicker than medial. The hindlimb SL had a single large area of origin. In fore- and hindlimbs, the amount of muscular tissue was significantly larger laterally than medially. Overall SL measurements using MRI were significantly higher than using histology and ultrasonography and histological higher than ultrasonographic measurements. Morphologically, there was a good correlation between MRI and histology. CONCLUSIONS: MRI provides more detailed information than ultrasonography regarding muscle fibre detection and OSL dimension and correlates morphologically well with histology. Therefore, ultrasonographic results should be regarded with caution. POTENTIAL RELEVANCE: MRI may be a diagnostic aid when other modalities fail to identify clearly the cause of proximal metacarpal and metatarsal pain; and may improve selection of adequate therapy and prognosis for injuries in this region.

Animals↗

PubMed2005

Tetrahydrogestrinone is a potent but unselective binding steroid and affects glucocorticoid signalling in the liver.

Tetrahydrogestrinone (THG) is a steroid recently identified to be misused as doping agent. However, the knowledge on functions of this substance in humans or animal models is rather limited. Therefore, it was our aim to further characterize the pharmacological profile of THG and identify potential adverse side effects. THG was synthesized, the purity was confirmed and its biological activity was tested. The potency of THG to transactivate AR dependent reporter gene expression was two orders of magnitude lower compared to dihydrotestosterone. THG binds with high affinity but unselective to the androgen (AR), progesterone (PR), glucocorticoid (GR) and mineralocorticoid (MR) receptor. Treatment of orchiectomised rats with THG resulted in a stimulation of prostate, seminal vesicle and levator ani muscle, indicating androgenic and anabolic properties. In the liver THG, in contrast to testosteronepropionate (TP), down regulates the expression of the GR dependent tyrosine aminotransferase gene (TAT). In summary, our results demonstrate that THG is not a specific AR agonist. THG exhibits a high binding affinity to all tested steroid hormone receptors and binds with highest affinity to the GR. Our in vivo data are indicative of an anabolic and androgenic potency of THG, but the repression of TAT demonstrates that THG also interferes with the glucocorticoid hormone system. Therefore, it is conceivable that an intake will result in adverse side effects.

Anabolic Agents↗

PubMed2005

Identification of the aromatase inhibitor letrozole in urine by gas chromatography/mass spectrometry.

Letrozole (1-(bis-(4-cyanophenyl)methyl)-1,2,4-triazole) is used therapeutically as a non-steroidal aromatase inhibitor (Femara) to treat hormone-sensitive breast cancer in postmenopausal women. For doping purposes it may be used to counteract the adverse effects of an extensive abuse of anabolic androgenic steroids (gynaecomastia) and to increase the testosterone concentration by stimulation of the testosterone biosynthesis. The use of aromatase inhibitors has been prohibited by IOC/WADA regulations for male and female athletes since September 2001 and January 2005, respectively. Spot urine samples from women suffering from metastatic breast cancer and being treated with letrozole were collected and analysed to develop/optimise the detection system for metabolites of letrozole to allow the identification of athletes who do not comply with the internationally prohibited use of this cancer drug. The assay was based on gas chromatography/mass spectrometry (GC/MS) and the main metabolite of letrozole (bis-4-cyanophenylmethanol) was identified by comparison of its mass spectrum and retention time with that of a bis-4-cyanophenylmethanol reference. The full-scan spectrum, diagnostic ions and a validation of the method for the analysis of bis-4-cyanophenylmethanol are presented.

Aromatase Inhibitors↗

PubMed2005

[Anatomy of the splint bones and their surrounding area particularly in consideration of fascial attachments].

This study concerns the vestigial metacarpal and metatarsal bones, so called splint bones. The soft tissues, which stabilize the splint bones were carefully examined. The palmar metacarpal/plantar metatarsal fascia, the metacarpal/metatarsal interosseous ligaments and the fibres, which exit distally from the splint bone, were examined in depth. Cadaveric distal limbs were collected from 5 slaughtered or euthanized horses. The legs were examined both, microscopically and macroscopically. The palmar metacarpal/plantar metatarsal fascia is a very stable structure, which connects the splint bone with its environment. The connection between splint and McIII/MtIII, established through the metacarpal/ metatarsal interosseous ligaments, showed impressive differences between specimens examined. Macroscopic examination of the soft tissue in the distal region showed a band structure, which originates from the distal end of the splint bone and extends in dorsal and distal direction towards the proximal sesamoid bone.

Animals↗

PubMed2004

The bovine digital cushion--a descriptive anatomical study.

The properties of the suspensory and supporting structures of the bovine claw are of particular importance in the pathogenesis of claw lesions since both must function optimally to prevent soft tissue compression and trauma. An essential component is the shock-absorbing digital cushion situated under the distal phalanx. The sound claws of 54 slaughtered cows were dissected. The digital cushion consisted of three parallel pads--axial, middle and abaxial--that ran longitudinally from the heel and underneath the distal phalanx with numerous transverse finger-shaped branches that connected the axial and abaxial pads cranial to the flexor process of the distal phalanx. The middle fat pad frequently ended just at the apical end of the flexor process of the distal phalanx, which may result in an inferior cushioning effect under the distal phalanx and increase the likelihood of ulcers. There were differences in the structure of the digital cushion with age and loose connective tissue in heifers' pads was first replaced by fat which, after the third lactation, was gradually supplanted by collagenous connective tissue.

Animals↗

PubMed2004

Analysis of non-hormonal nutritional supplements for anabolic-androgenic steroids - results of an international study.

Several recent studies have shown evidence of some nutritional supplements containing prohibited anabolic androgenic steroids, so-called prohormones, which were not declared on the label. Therefore, a broad-based investigation of the international nutritional supplement market was initiated to clarify the extent of this problem. From October 2000 until November 2001, 634 non-hormonal nutritional supplements were purchased in 13 countries from 215 different suppliers. Most supplements were bought in shops in the respective countries (578 samples = 91.2 %) and on the internet (52 samples = 8.2 %). 289 supplements were from prohormone-selling companies and 345 supplements came from companies which do not offer prohormones. After isolation from the supplement matrix 11 different anabolic androgenic steroids, mainly prohormones of testosterone and nandrolone, were analysed by gas-chromatography/mass spectrometry. Out of the 634 samples analysed 94 (14.8 %) contained anabolic androgenic steroids not declared on the label ("positive supplements"). We could not obtain reliable data for 66 samples (10.4 %) due to matrix effects. In relation to the total number of products purchased per country, most of the positive supplements were bought in the Netherlands (25.8 %), in Austria (22.7 %), in the UK (18.8 %) and the USA (18.8 %). According to the label, all positive supplements were from companies located in only five countries: the USA, the Netherlands, the UK, Italy and Germany. 21.1 % of the nutritional supplements from prohormone-selling companies contained anabolic androgenic steroids, whereas 9.6 % of the supplements from companies not selling prohormones were positive. The positive supplements showed anabolic androgenic steroid concentrations of 0.01 micro g/g up to 190 micro g/g. The administration of supplements containing nandrolone prohormones adding up to a total uptake of more than 1 micro g resulted in positive doping results for norandrosterone for several hours.

Adult↗

PubMed2004

Analytical strategies for the detection of non-labelled anabolic androgenic steroids in nutritional supplements.

Recent studies showed that non-hormonal supplements such as vitamins, minerals and amino acids can contain anabolic androgenic steroids not declared on the labels of the products. These undeclared substances (often prohormones of testosterone or 19-nortestosterone) can cause health risks to consumers and might lead to positive results in sports doping control, especially for the nandrolone metabolite norandrosterone. The analysis of nutritional supplements for anabolic steroids has proven to be rather difficult due to the different matrices in the various products. To conduct a broad-based analysis, a few robust methods capable of analysing various matrices are needed. To obtain a sensitive gas chromatography-mass spectrometry (GC-MS) analysis, a method including extraction and purification of the analytes followed by GC-MS analysis of the trimethylsilyl (TMS) derivatives of the steroids was developed. The limit of detection was improved by the addition of a mixture of 1-N,N-diisopropylamino-n-alkanes (DIPAs) to the final extract. In pure creatine monohydrate powder the limits of detection were demonstrated to be 0.1 ng microg (-1) for dehydroepiandrosterone (DHEA) and estr-4-ene-3beta,17beta-diol, 0.7 ng g(-1) for 5alpha-androstane-3beta,17beta-diol and androsta-1,4-diene-3,17-dione, 1 ng g(-1) for estr-5-ene-3beta,17beta-diol, estr-4-ene-3,17-dione, 19-nortestosterone, androst-4-ene-3, 17-dione and testosterone, and 2 ng g(-1) for androst-4-ene-3beta,17beta-diol and androst-5-ene-3beta,17beta-diol. The recovery (determined at 200 ng g(-1)) ranged from 32% for 19-nortestosterone to 92% for androst-5-ene-3beta,17beta-diol. During the investigation of different nutritional supplements, several analytical difficulties occurred. Aspects of homogenization, extraction, separation, derivatization and GC-MS measurement as well as strategies for the solution of problems arising were optimized. For quantitative measurements of the steroids in nutritional supplements, deuterated internal standards of the specific steroids or standard addition are necessary to compensate for matrix effects.

Alkanes↗

PubMed2002

Suspensory structures and supporting tissues of the third phalanx of cows and their relevance to the development of typical sole ulcers (Rusterholz ulcers).

The mural suspensory apparatus of third phalanx and its supportive heel cushion were examined in 19 cows with an ulcer at the 'typical' site (Rusterholz ulcer) to gain information on the pathogenesis of sole and heel ulcers. The claws of 17 healthy controls were used for comparison. The left hind claws, frozen at -20 degrees C, were sectioned in one longitudinal and four transverse planes with a band saw. The thickness of the subcutaneous tissue, the corium and the extent of displacement of the third phalanx were measured at defined sites on these sections. In addition, the suspensory apparatus, the tissue layer connecting the third phalanx to the dorsal wall of the horn capsule, was examined histologically. There was a direct relationship between the displacement of the third phalanx and ulceration of the sole or heel; in all the ulcerated claws the third phalanx had dropped and the corium and the subcutis under the bone were thinner than in the controls. The supportive cushions of the cows with ulcers contained less fat tissue. There was no histological evidence of damage to the epidermis or the corioepidermal junction in the ulcerated claws nor were the lamellae elongated. Similarly, there were no morphological changes in the connective tissue layer, the submural dermis.

Animals↗

PubMed2002

Identification of the aromatase inhibitor aminoglutethimide in urine by gas chromatography/mass spectrometry.

Aminoglutethimide is used therapeutically as an aromatase inhibitor in the treatment of metastatic breast cancer in post-menopausal women. For doping purposes, aminoglutethimide may be used for treatment of adverse effects of an extensive abuse of anabolic androgenic steroids (gynaecomastia) and to increase the testosterone concentration and stimulation of testosterone biosynthesis. The use of aromatase inhibitors has been prohibited for male athletes since September 1, 2001. The purpose of this study was to develop methods for the identification of the parent compound or its main metabolite and the inclusion of this information into established screening procedures in doping analysis. An excretion study was conducted using oral application of one single therapeutic dose (500 mg) of Orimeten. The analysis was performed by gas chromatography/mass spectrometry (GC/MS). Aminoglutethimide is excreted almost totally as unconjugated parent compound and is detectable by different screening procedures for up to 165 h. Most suitable for the detection of aminoglutethimide is the screening procedure for heavy volatile nitrogen-containing drugs ('Screening 2'). However, since only competition samples are analysed in that screening procedure, the additional inclusion of aminoglutethimide in the screening procedure for anabolic androgenic agents ('Screening 4') is recommended. Full mass spectra and diagnostic ions for the analysis of aminoglutethimide are presented.

Adrenergic Agents↗

PubMed2002

[Cardiomyopathy associated with uncontrolled self medication of anabolic steroids].

Though doping has become increasingly ostracized in the context of professional sports, an enormous number of unrecorded cases must be assumed in semi-professional competitive sports as well as in popular sports. This holds especially true for those forms of sports which are done in order to obtain a well-proportioned, athletic, healthy looking body. This case report describes a formerly healthy young man who had to be urgently admitted to an intensive care unit due to severe myocardial pump failure. As anamnestic information was insufficient and inadequate, the taking of anabolic steroids in high doses was proven, as their metabolites could be detected by urine analysis. Until now, myocardial contractile dysfunction has persisted for more than twelve months after the initial admission. Though other diagnoses which might have led to this impaired myocardial contractile performance have been excluded, cardiomyopathy associated with the taking of anabolic steroids must be assumed. Even in non-professional and public sports, a widespread abuse of doping substances exists. Hence, cardiomyopathy associated with the misuse of anabolic steroids has to be considered especially in young, formerly healthy patients.

Adult↗

PubMed2002

Effect of therapeutic dietary biotin on the healing of uncomplicated sole ulcers in dairy cattle--a double blinded controlled study.

The objective of this study was to investigate the influence of orally administered biotin on the healing of uncomplicated sole ulcers in dairy cattle. In a double-blind controlled study, 24 dairy cows with a mild, uncomplicated sole ulcer on a lateral hind claw were given either 40 mg biotin per day or a placebo feed over a period of 50 days. An orthopaedic shoe was fitted to the medial claw of the affected foot. The healing process was assessed clinically and by histological examination of horn samples. In the biotin-treated animals, the newly formed epidermis covering the sole ulcers was found to be of significantly better histological quality after 50 days than at the start of the study. The significant improvement in histological horn quality found in the biotin-treated animals suggests that biotin exerts a positive influence on the healing of sole ulcers, however the study period of 50 days appears to have been too short to permit macroscopic detection of the improvement in horn quality.

Administration, Oral↗

PubMed2001

Two glycoforms are present in the GPI-membrane anchor of the surface antigen 1 (P30) of Toxoplasma gondii.

SAG1 (P30) is the major surface protein of the Toxoplasma gondii tachyzoite, the life cycle stage associated with the acute phase of infection. The protein is inserted into the parasite's plasma membrane by a glycosyl-phosphatidylinositol anchor, a modification that is present on all T. gondii surface proteins characterized so far. Here we describe a detailed structural analysis of this anchor. GPI anchor peptides were isolated from [3H]glucosamine labeled purified P30 by protease digestion and phase partitioning. Neutral glycans were prepared from this material by dephosphorylation and deamination. Two glycoforms were characterized by gel filtration and high performance ion exchange chromatography in combination with exoglycosidase treatment. Both forms were shown to carry an N-acetylgalactosamine bound to the first mannose of the conserved three-mannosyl core. Glycan B carries an additional terminal hexose linked to GalNAc. To identify the nature of this hexose, bulk anchor peptide was prepared and glycans were purified by aminopropyl-HPLC. Highly purified glycans were subjected to MALDI-TOF-MS and, after derivatization, to FAB-MS and methylation linkage analysis. The structures of the two anchors found on SAG1 were determined to be: Man-alpha1,2-Man-alpha1,6-Man-[GalNAc-beta1,4-]-alpha1,4-GlcN-PI and Man-alpha1,2-Man-alpha1,6-Man [Glc-alpha1,4-GalNAc-beta1,4-]-alpha1,4-GlcN-PI. Comparison of these structures with free GPI glycolipid precursors characterized in T. gondii suggests that core modification of the anchor takes place prior to transfer to the protein.

Animals↗