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Androgens are essential for the development and maintenance of spermatogenesis, but the underlying mechanisms of androgen action in the testis remain unclear. To help clarify these mechanisms, gene expression was measured in testes of pubertal (20 d old), androgen-insensitive, testicular feminized (Tfm) mice and in normal controls. Using microarrays (Affymetrix chips 430A and 430B), initial data identified a large number of genes down-regulated in the Tfm testis (>4700). These genes were largely of germ cell origin, reflecting the arrest of spermatogenesis that is apparent in the 20-d-old Tfm testis. Subsequent screening in vitro and in silico of this gene set identified 20 genes of a somatic tubular origin that were significantly down-regulated in the Tfm testis and six genes that were significantly up-regulated. Altered expression of these genes was confirmed by real-time PCR, and genes down-regulated in the Tfm testis were shown to be up-regulated in testes of hypogonadal (hpg) mice treated with androgen. In a developmental study using real-time PCR most of the regulated genes showed normal expression during fetal and neonatal development and deviated from control only between 10 and 20 d. In all cases, expression was also reduced in the adult, although interpretation is more complex because of the inherent cryptorchidism in the adult Tfm mouse. Of the total number of somatic genes showing differential expression in the Tfm testis, 50% were associated with three separate groups of genes involved in regulation of vitamin A metabolism, solute transportation, and cytoskeletal function. Thus, effects of androgens on tubular function and spermatogenesis may be mediated in part through regulation of the tubular environment and control of retinoic acid concentrations.

To identify genes developmentally regulated in the somatic cells of the testis, serial analysis of gene expression (SAGE) has been used to generate gene expression profiles from these cells in the fetal and adult mouse. To avoid germ cell transcripts, a fetal SAGE library was generated from germ cell-free fetal Wv/Wv mice, and an adult SAGE library was generated from adult testes depleted of germ cells with busulfan. The combined SAGE libraries contained 147570 tags identifying 12976 unique transcripts. Of these transcripts, 3607 were present in only the fetal library and 3941 were present in only the adult library. Most of the abundant differentially expressed tags in the adult testis library were from characterized genes, whereas 3' rapid amplification of complementary ends was required to identify most differentially expressed tags in the fetal library. These fetal tags were mostly associated with uncharacterized UniGene clusters. These data provide a comprehensive and quantitative analysis of gene expression in the somatic cells of the fetal and adult testis (including unknown transcripts) and identify genes differentially expressed in these cells during testis development. These differentially regulated genes are likely to provide insight into mechanisms regulating testis function both during development and in the adult animal.

Urine albumin excretion was studied by two widely accepted methods in 210 patients with insulin-dependent diabetes mellitus and related to the mean of serial glycosylated haemoglobin (HbA1) measurements made every 3 months during the previous 6 years. Microalbuminuria (albumin excretion rate > 20 micrograms/min) was present in 9.5 per cent of patients when defined by a 24-hour collection and 8.1 per cent of patients when defined by a timed overnight urine sample. Those with microalbuminuria, as estimated from a timed overnight urine sample, had a longer duration of diabetes but otherwise did not differ in age, duration of diabetes or arterial blood pressure from patients whose albumin excretion rate was 20 micrograms/min or less irrespective of the method of urine collection. The mean and the most recent HbA1 levels differed significantly between the normal and the microalbuminuric groups when defined by the 24-hour albumin excretion rate (p < 0.001, p < 0.01), but no significant difference between these groups was found when albumin excretion rates were calculated from the timed overnight urine sample. Albumin excretion rate, examined in relation to mean HbA1, increased significantly with worsening glycaemic control whether measured over 24 hours or overnight (p < 0.05, p < 0.01). These findings support an association between glycaemic control and microalbuminuria, but the correlation is weak, dependent on the method of urine collection and is just as good for a relatively short-term as for a long-term measure of average blood glucose.