Development of a radioimmunoassay for measuring gonadotrophin releasing hormone in patients receiving treatment

Advances and perspectives in the analytical technology for small peptide hormones analysis: A glimpse to gonadorelin

In the last twenty years, we have witnessed an important evolution of bioanalytical approaches moving from conventional lab bench instrumentation to simpler, easy-to-use techniques to deliver analytical responses on-site, with reduced analysis times and costs. In this frame, affinity reagents production has also jointly advanced from natural receptors to biomimetic, abiotic receptors, animal-free produced. Among biomimetic ones, aptamers, and molecular imprinted polymers (MIPs) play a leading role. Herein, our motivation is to provide insights into the evolution of conventional and innovative analytical approaches based on chromatography, immunochemistry, and affinity sensing referred to as peptide hormones. Indeed, the analysis of peptide hormones represents a current challenge for biomedical, pharmaceutical, and anti-doping analysis. Specifically, as a paradigmatic example, we report the case of gonadorelin, a neuropeptide that in recent years has drawn a lot of attention as a therapeutic drug misused in doping practices during sports competitions.

Has GnRH a direct role in AMH regulation?

OBJECTIVE

Anti-Mullerian hormone (AMH) together with luteinizing hormone (LH) and follicle-stimulating hormone (FSH) plays crucial roles in gonadal functions. However, the possible effects of GnRH on AMH via the hypothalamic-pituitary-gonadal (HPG) axis remain unexplored. We aimed to explore the changes in AMH levels after bolus GnRH stimulation and understand the relationship of AMH with FSH and LH in healthy subjects.

METHODS

Thirty-one prepubertal children (15 males/16 females) and 78 adults (36 males/42 females) were included. We collected basal (0 minute) samples for determining levels of hormones. After GnRH treatment at a dose of 2.5 μg/kg body weight (maximum of 100 μg/kg body weight) intravenously, blood was collected at 30 minutes intervals for 120 minutes. Serum LH, FSH and AMH were measured by electrochemiluminometric assays.

RESULTS

After injection of GnRH, AMH levels were significantly decreased in 30 minutes (P < 0.001) in all groups with parallel increase of FSH and LH. In the second 30 minutes, all hormones levels reversed. There was also a moderate correlation between AMH and FSH (r = -0.430, P < 0.001).

CONCLUSIONS

GnRH lowers serum AMH levels, which have a negative correlation with the increase in gonadotrophins. These data pinpoint GnRH as an important factor of the AMH regulation, leading new opportunities for the understanding of AMH role in reproductive function and dysfunction.

Early photocoagulation in patients with either type I or type II diabetes

OBJECTIVE

To determine the benefits of early photocoagulation in patients with type I versus type II diabetes.

DESIGN

One eye of each of 3,711 patients was randomly assigned to early photocoagulation; the other was assigned to deferral of photocoagulation, with follow-up visits scheduled every 4 months and photocoagulation to be carried out promptly if high-risk proliferative retinopathy developed. Patients were categorized by age and type of diabetes.

MAIN OUTCOME MEASURES

Best corrected visual acuity was measured at each study visit scheduled at 4-month intervals. Stereoscopic fundus photographs were taken and evaluated at baseline, 4 months, and yearly thereafter. Retinopathy severity was assessed from fundus photographs. Severe visual loss was defined as visual acuity of worse than 5/200 for at least two consecutive study visits.

RESULTS

Previously published results of the Early Treatment Diabetic Retinopathy Study (ETDRS) demonstrated a statistically significant benefit of early photocoagulation in preventing severe vision loss. Further analyses demonstrate that this benefit of early photocoagulation is greater in patients with type II diabetes than in those with type I. The relative benefit of early photocoagulation in patients with type II diabetes is also seen for other outcomes (development of high-risk proliferative retinopathy, development of the combined end point [severe visual loss or vitrectomy], development of moderate visual loss, or development of legal blindness). The patients most likely to benefit from early photocoagulation had severe nonproliferative retinopathy or early proliferative retinopathy. Analyses from the Diabetic Retinopathy Study confirm the relative benefit of scatter photocoagulation for type II patients. Because of the high correlation between age and type of diabetes, analyses sub-grouped by age show similar results.

CONCLUSION

These analyses suggest that patients with type II diabetes, or older patients with diabetes, are more likely to benefit from early scatter photocoagulation than patients with type I diabetes. The current standard of care is to initiate scatter photocoagulation as the severity of retinopathy approaches or reaches the high-risk stage, Provided careful follow-up is possible, ETDRS data do not show that initiating scatter photocoagulation prior to the development of high-risk proliferative diabetic retinopathy in patients with type I diabetes will reduce the risk of severe visual loss. ETDRS analyses do indicate that for patients with type II diabetes, it is especially important to consider scatter photocoagulation at the time of the development of severe nonproliferative or early proliferative retinopathy.