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De diagnose van cryptorchidie bij het paard is vaak een uitdaging aangezien niet altijd definitief uitsluitsel kan gegeven worden op basis van de anamnese, het klinische onderzoek en het rectaal en echografisch onderzoek. Verschillende endocrinologische diagnostische testen zoals de bepaling van het testosteron-, androstenedione-, oestrogenen-, urinaire steroïden- en het antimülleriaans hormoongehalte, die de aanwezigheid van testiculair weefsel aantonen, zijn beschreven. In dit artikel wordt getracht om de voor- en nadelen van deze testen te vergelijken, zodat practici een idee krijgen welke testen in de praktijk gebruikt kunnen worden.

The field of Rhodococcus cell engineering is rapidly advancing because of the availability of improved genetic tools and increased insights in their broad catabolic and biochemical diversity. Rhodococci harbor large linear plasmids that may contribute to their catabolic diversity. In addition, multiple pathways and gene homologs are often present, thus further increasing Rhodococcus catabolic versatility and efficiency. The recent development of effective genetic tools for Rhodococcus, such as unmarked gene deletion, transposon-based mutagenesis, and gene expression systems, now allows the construction of biocatalysts with desirable properties for industrial purposes. This is exemplified here by a description of cell engineering of biocatalysts for improved desulphurization and steroid biotransformation.

Premature pubarche is defined as growth of pubic hair before the age of 8 years in girls and 9 years in boys. In most cases, it is caused by premature adrenarche, which is a premature increased synthesis of androgens in the adrenal gland and is considered to be relatively harmless. Premature pubarche can also result from severe pathology, which makes it necessary to find the cause of premature exposition to androgens. We present 3 girls, aged 5-8 years, with premature pubarche. They were eventually diagnosed with 'premature adrenarche', 'non-classical congenital adrenal hyperplasia' and 'adrenal adenoma', respectively. No treatment is indicated for premature adrenarche. The patient with non-classical congenital adrenal hyperplasia was treated with hydrocortisone; in the patient with an adrenal adenoma - a rare but severe condition - the adenoma was resected. The diagnoses were established based on progression of growth, bone age and serum levels of dehydroepiandrosterone sulfate (DHEAS), androstenedione, testosterone and 17-hydroxyprogesterone. Fast progression of pubarche, accelerated growth velocity and advanced bone age should be considered alarm symptoms in patients with premature pubarche.

Congenital adrenal hyperplasia (CAH) is a disorder of adrenal steroid synthesis. In more than 90% of cases CAH is caused by CYP21 (21-hydroxylase) deficiency leading to impaired cortisol and aldosterone synthesis and an increase in ACTH secretion. This then leads to stimulation of the adrenal gland and overproduction of androgens with virilisation of female external genitalia. The CYP21 enzyme consists of 495 amino acids and is encoded by the CYP21A2 gene located on chromosome 6p21.3 close to a 98% homologous pseudogene (CYP21p). The pseudogene contains several inactivating mutations that may be transferred to the active CYP21A2 gene by gene conversion (more than 60% of the affected alleles) or gene deletion (30% of the affected alleles). The severity of the disease depends on the degree of CYP21 deficiency. The diagnosis can be made by measuring levels of 17-hydroxyprogesterone and androstenedione in serum.

The development of pre-ovulatory bovine follicles from the onset of oestrus until ovulation may be divided into four phases on the basis of the patterns of the steroid levels in the follicular fluid. Changes in the morphology of the follicular wall and the oocyte coincide with these patterns. Prior to the pre-ovulatory LH surge steroid synthesis is directed towards the production of oestradiol-17 beta, and androstenedione is the major substrate of aromatase. After the LH peak, steroid synthesis switches to the production of progesterone shortly prior to ovulation. The membrana granulosa cell-layer shows morphological luteinization at the time. The elevated levels of LH and FSH observed in the follicular fluid suggest that changes in the micro-environment of the maturing bovine oocyte are regulated by these gonadotrophins.