Purine phosphoribosyltransferase (EC 2.4.2.7 and 2.4.2.8) and purine de novo synthesis activity in rat testicular tissue at different stages of development, and their correlation with the circulating levels of gonadotrophins and testosterone, and with structural changes

The Association between Serum Testosterone and Hyperuricemia in Males

Gout is a common systemic inflammatory disease with a male predominance. This study aimed to determine the relationship between serum total testosterone level and hyperuricemia. Data on 1899 men, collected from 2007 to 2017, were included in the analysis. Serum testosterone and urate (SU) were measured on enrolment. The primary endpoints were SU levels ≥ 7 mg/dL and ≥9 mg/dL. On enrolment, participants had a mean age of 45.6 years and mean total testosterone and SU levels of 510 ng/dL and 6.6 mg/dL, respectively. The mean total testosterone levels were 533 and 470 ng/dL in patients with SU levels < 7 mg/dL and ≥7 mg/dL, respectively (p < 0.001); and 515 and 425 ng/dL in patients with SU levels < 9 mg/dL and ≥9 mg/dL, respectively (p < 0.001). After adjusting for age, body mass index, creatinine, serum lipid, fasting blood glucose, systolic blood pressure, and diastolic blood pressure, low testosterone level (<400 ng/dL) was significantly associated with an SU level ≥ 7 mg/dL (hazard ratio: 1.182, 95% confidence interval: 1.005−1.39) and ≥9 mg/dL (hazard ratio: 1.905, 95% confidence interval: 1.239−2.928). In men, a low testosterone level may be associated with an increased risk of hyperuricemia.

Semiquantitative analysis of X-linked gene expression during spermatogenesis in the mouse: ethidium-bromide staining of RT-PCR products

We have used analysis of ethidium-bromide-stained reverse transcriptase-polymerase chain reaction (RT-PCR) products to assess the effects of X-chromosome inactivation during spermatogenesis in the mouse. RT-PCR was performed on total RNA from eight different spermatogenic cell types, including premeiotic spermatogonia, meiotic spermatocytes, and postmeiotic spermatids, to detect transcripts from five different X-linked structural genes (Pgk-1, Zfx, Pdha-1, Hprt, and Phka) and two autosomal genes (Pgk-2 and beta-actin). Relative intensities of ethidium-bromide-stained RT-PCR products representing transcripts from each gene in each cell type were analyzed by densitometry using the Image program (version 1.4, NIH), and normalized against beta-actin values. These results suggest a coordinate inactivation of the X-linked loci at the onset of meiosis, followed by variable rates of decline of corresponding transcript levels reflecting differential mRNA stabilities and/or leaky expression after inactivation. Technically, these results indicate that analysis of ethidium-bromide-stained RT-PCR products can be used to provide a "semiquantitative" indication of relative levels of specific transcripts in a developing cell lineage without using radioactive probes to quantitate these products.

Measurement by quantitative PCR of changes in HPRT, PGK-1, PGK-2, APRT, MTase, and Zfy gene transcripts during mouse spermatogenesis

A reverse transcriptase-polymerase chain reaction assay (RT-PCR) was used quantitatively to measure accumulated levels of RNA transcripts in total mouse RNAs derived from male germ cells at various spermatogenic stages. RNA levels for two X-linked enzymes, phosphoglycerate kinase (PGK-1) and hypoxanthine phosphoribosyl transferase (HPRT), both decrease during spermatogenesis, although the transcript levels decrease much more rapidly for PGK-1. RNA for the Y-linked ZFY (zinc finger protein) is elevated in all spermatogenic cell fractions tested, being particularly high in leptotene/zygotene spermatocytes and round spermatids. RNA for adenine phosphoribosyltransferase (APRT) increases 5-fold to a peak during late pachynema. RNA for PGK-2, undetectable in spermatogonial cells, increases at least 50-fold by the round spermatid stage. DNA (cytosine-5-)-methyltransferase (MTase) transcript levels are over an order of magnitude higher throughout spermatogenesis than in non-dividing liver cells.

Hypoxanthine phosphoribosyltransferase activity in tissues and hypoxanthine concentrations in plasma and CSF of the horse in comparison with other species

1. Plasma hypoxanthine and xanthine concentrations are very low in the horse and low in rat, mouse and greyhound compared to concentrations in beagles, man, sheep and rabbit. 2. Activities in erythrocytes of the main enzyme metabolizing hypoxanthine, hypoxanthine phosphori-bosyltransferase, show a similar pattern (Tax et al., 1976, Comp. Biochem. Physiol. 54B, 209-212); thus low activities have been found where plasma concentrations were low. 3. Hypoxanthine phosphoribosyltransferase activities in horse tissue other than erythrocytes are similar to those in man and rabbit with high activities in brain; this enzyme may therefore be functionally important in equine brain.

Lesch-Nyhan syndrome: growth delay, testicular atrophy and a partial failure of the 11 beta-hydroxylation of steroids

There is a failure of growth in hypoxanthine guanine phosphoribosyltransferase deficiency; slow weight gain is marked after the second year of age but is apparent in the birth weights of all eight of our patients for whom we have data. However, head growth and bone development are less affected than weight. A partial defect in the adrenocortical 11 beta-hydroxylation of steroids was demonstrated after ACTH stimulation in all four patients studied. This hydroxylation takes place in mitochondria the function of which is modulated by purine nucleotide concentrations; this may be the link with the enzyme defect. Testicular atrophy at autopsy was found in two pubertal age boys and seven patients aged 12-17 years had no signs of puberty. All five boys aged 3-11 years showed less than the normal mean response of plasma testosterone concentration to human chorionic gonadotrophin despite the normal histological appearance of the testes of one 6-year-old-boy. Follicle stimulating hormone responses to gonadotrophin releasing hormone are probably less than in normal in at least three of the seven prepubertal boys. The absence of the normally high activities of hypoxanthine guanine phosphoribosyltransferase in testes appears to inhibit their ability to respond to gonadotrophin.