Limited · humanPreprint
This bioinformatics study investigated the role of melatonin-related genes in coronary heart disease (CHD) by analyzing two publicly available gene expression datasets (GSE179789 and GSE113079). Using differential expression analysis and validation, the researchers identified two genes—MAP2K2 (a mitogen-activated protein kinase kinase) and PGD (phosphogluconate dehydrogenase)—as candidate CHD biomarkers, both showing significant upregulation in CHD samples across both datasets. Gene set enrichment analysis (GSEA) linked these genes to pathways including ribosome function, prion diseases, and Parkinson's disease. The study also mapped complex regulatory networks involving lncRNAs, miRNAs, and transcription factors; notably, four lncRNAs (NEAT1, AP000766.1, LINC02381, and XIST) were found to regulate PGD via hsa-let-7e-5p, and 29 transcription factors co-regulated both biomarkers. Drug-target network analysis predicted 41 drugs targeting MAP2K2 and 3 targeting PGD. Biomarker expression was further validated in clinical samples via RT-qPCR. Limitations include the observational and computational nature of the study, reliance on public datasets, small clinical validation cohorts typical of such designs, and the absence of functional or mechanistic experiments confirming causal roles. The study is reported as a preprint and has not undergone formal peer review.
Unknown journal · Apr 2026DOI ↗ Animal only
This study characterized growth hormone (GH) secretion patterns and responsiveness to exogenous GH-releasing hormone (GHRH) in adult male cynomolgus monkeys, with the goal of evaluating their suitability as a model for pituitary toxicity research. Two groups of ten animals were used to assess diurnal and day-to-day GH variation via serial serum sampling, while a separate four-animal-per-group crossover examined GH responses to intravenous pralmorelin hydrochloride (a GHRH analog) versus saline. GH was measured by ELISA. The study found a diurnal pattern resembling that of humans, with GH rising in the late morning, dipping around midday, and peaking at night. Considerable inter- and intra-individual daily variation was also observed over five consecutive days. In the stimulation test, GHRH-treated animals showed significantly higher GH concentrations at 0.5 and 1 hour post-administration compared to controls. The authors conclude that cynomolgus monkeys share key GH secretion characteristics with humans and may serve as a relevant non-clinical model. Limitations include small sample sizes, male-only subjects, and the non-human primate setting, meaning direct translation to human physiology or clinical applications requires caution.
In vivo (Athens, Greece) · Jan 2026DOI ↗ Limited · human
This study developed and validated an analytical method for detecting a broad panel of 18 performance-enhancing peptides (molecular weight <2 kDa) in human urine, as defined by the World Anti-Doping Agency (WADA) prohibited list. The method uses direct urine injection—bypassing complex sample preparation—coupled with liquid chromatography and ion mobility time-of-flight mass spectrometry (IM-TOFMS). The researchers reported limits of detection (LOD) ranging from 50 to 500 pg/mL, well below WADA's minimum required performance level of 2 ng/mL. The method demonstrated acceptable precision (imprecision <20%) and linearity across a 0–10 ng/mL working range. Stability testing identified –20°C as the appropriate storage temperature for urine samples. As a proof-of-concept, the method was applied to real elimination study urine samples from individuals who had administered GHRP-2, GHRP-6, or LHRH, successfully detecting these compounds. Key limitations include the small number of human subjects used in the elimination studies, which were primarily intended to demonstrate analytical feasibility rather than investigate pharmacokinetics or clinical effects. The study is a methodological/analytical validation paper focused on anti-doping screening, not a clinical or therapeutic investigation.
Journal of separation science · Dec 2015DOI ↗ Animal only
This study compared the pharmacokinetics of five peptidyl growth hormone secretagogues — ipamorelin (NNC 26-0161), NNC 26-0194, NNC 26-0235, GHRP-2, and GHRP-6 — in male rats using multiple routes of administration, with a particular focus on nasal delivery. Following intravenous bolus injection, all peptides showed biexponential plasma concentration decline. Ipamorelin stood out with a systemic plasma clearance approximately five times lower than GHRP-6. Excretion routes differed: ipamorelin was primarily cleared via urine, while GHRP-6 and the two NNC peptides were predominantly excreted in bile. Metabolic stability was moderate for ipamorelin and the NNC peptides, with 60–80% of administered doses recoverable as intact peptide from bile and urine combined. Intranasal bioavailability of ipamorelin was estimated at approximately 20%, while NNC 26-0235, NNC 26-0194, and GHRP-2 achieved approximately 50% nasal bioavailability. The authors concluded that nasal delivery appears to be a promising route for this peptide class. Key limitations include exclusive use of animal subjects (male rats), meaning findings may not directly translate to humans, and the study did not assess pharmacodynamic or safety endpoints.
Xenobiotica; the fate of foreign compounds in biological systems · Nov 1998DOI ↗