Hypertensive rats show increased renal excretion and decreased tissue concentrations of glycine betaine, a protective osmolyte with diuretic properties.

Hypertension leads to water-electrolyte disturbances and end-organ damage. Betaine is an osmolyte protecting cells against electrolyte imbalance and osmotic stress, particularly in the kidneys. This study aimed to evaluate tissue levels and hemodynamic and renal effects of betaine in normotensive and hypertensive rats. Betaine levels were assessed using high-performance liquid chromatography-mass spectrometry (HPLC-MS) in normotensive rats (Wistar-Kyoto, WKYs) and Spontaneously Hypertensive rats (SHRs), a model of genetic hypertension. Acute effects of IV betaine on blood pressure, heart rate, and minute diuresis were evaluated. Gene and protein expression of chosen kidney betaine transporters (SLC6a12 and SLC6a20) were assessed using real-time PCR and Western blot. Compared to normotensive rats, SHRs showed significantly lower concentration of betaine in blood serum, the lungs, liver, and renal medulla. These changes were associated with higher urinary excretion of betaine in SHRs (0.20 ± 0.04 vs. 0.09 ± 0.02 mg/ 24h/ 100g b.w., p = 0.036). In acute experiments, betaine increased diuresis without significantly affecting arterial blood pressure. The diuretic response was greater in SHRs than in WKYs. There were no significant differences in renal expression of betaine transporters between WKYs and SHRs. Increased renal excretion of betaine contributes to decreased concentration of the protective osmolyte in tissues of hypertensive rats. These findings pave the way for studies evaluating a causal relation between depleted betaine and hypertensive organ damage, including kidney injury.

A Dhdds K42E knock-in RP59 mouse model shows inner retina pathology and defective synaptic transmission.

Retinitis pigmentosa (RP) defines a group of hereditary progressive rod-cone degenerations that exhibit a common phenotype caused by variants in over 70 genes. While most variants in the dehydrodolichyl diphosphate synthase (DHDDS) gene result in syndromic abnormalities, some variants cause non-syndromic RP (RP59). DHDDS encodes one subunit of the enzyme cis-prenyltransferase (CPT), which is required for the synthesis of dolichol (Dol), that is a necessary protein glycosylation cofactor. We previously reported the creation and initial characterization of a knock-in (KI) mouse model harboring the most prevalent RP59-associated DHDDS variant (K42E) to understand how defects in DHDDS lead to retina-specific pathology. This model exhibited no profound retinal degeneration, nor protein N-glycosylation defects. Here, we report that the Dol isoprenylogue species in retina, liver, and brain of the K42E mouse model are statistically shorter than in the corresponding tissues of age-matched controls, as reported in blood and urine of RP59 patients. Retinal transcriptome analysis demonstrated elevation of many genes encoding proteins involved in synaptogenesis and synaptic function. Quantitative retinal cell layer thickness measurements demonstrated a significant reduction in the inner nuclear layer (INL) and total retinal thickness (TRT) beginning at postnatal (PN) ∼2 months, progressively increasing to PN 18-mo. Histological analysis revealed cell loss in the INL, outer plexiform layer (OPL) disruption, and ectopic localization of outer nuclear layer (ONL) nuclei into the OPL of K42E mutant retinas, relative to controls. Electroretinograms (ERGs) of mutant mice exhibited reduced b-wave amplitudes beginning at PN 1-mo, progressively declining through PN 18-mo, without appreciable a-wave attenuation, relative to controls. Our results suggest that the underlying cause of DHDDS K42E variant driven RP59 retinal pathology is defective synaptic transmission from outer to inner retina.

Serum Metabolite Biomarkers for Pancreatic Tumors: Neuroendocrine and Pancreatic Ductal Adenocarcinomas-A Preliminary Study.

BACKGROUND: Pancreatic cancer is the most common pancreatic solid malignancy with an aggressive clinical course and low survival rate. There are a limited number of reliable prognostic biomarkers and a need to understand the pathogenesis of pancreatic tumors; neuroendocrine (PNET) and pancreatic ductal adenocarcinomas (PDAC) encouraged us to analyze the serum metabolome of pancreatic tumors and disturbances in the metabolism of PDAC and PNET. METHODS: Using the AbsoluteIDQ® p180 kit (Biocrates Life Sciences AG, Innsbruck, Austria) with liquid chromatography-mass spectrometry (LC-MS), we identified changes in metabolite profiles and disrupted metabolic pathways serum of NET and PDAC patients. RESULTS: The concentration of six metabolites showed statistically significant differences between the control group and PDAC patients (p.adj < 0.05). Glutamine (Gln), acetylcarnitine (C2), and citrulline (Cit) presented a lower concentration in the serum of PDAC patients, while phosphatidylcholine aa C32:0 (PC aa C32:0), sphingomyelin C26:1 (SM C26:1), and glutamic acid (Glu) achieved higher concentrations compared to serum samples from healthy individuals. Five of the tested metabolites: C2 (FC = 8.67), and serotonin (FC = 2.68) reached higher concentration values in the PNET serum samples compared to PDAC, while phosphatidylcholine aa C34:1 (PC aa C34:1) (FC = -1.46 (0.68)) had a higher concentration in the PDAC samples. The area under the curves (AUC) of the receiver operating characteristic (ROC) curves presented diagnostic power to discriminate pancreatic tumor patients, which were highest for acylcarnitines: C2 with AUC = 0.93, serotonin with AUC = 0.85, and PC aa C34:1 with AUC = 0.86. CONCLUSIONS: The observations presented provide better insight into the metabolism of pancreatic tumors, and improve the diagnosis and classification of tumors. Serum-circulating metabolites can be easily monitored without invasive procedures and show the present clinical patients' condition, helping with pharmacological treatment or dietary strategies.