Effects of Delivering Guanidinoacetic Acid or Its Prodrug to the Neural Tissue: Possible Relevance for Creatine Transporter Deficiency

The creatine precursor guanidinoacetate (GAA) was used as a dietary supplement in humans with no adverse events. Nevertheless, it has been suggested that GAA is epileptogenic or toxic to the nervous system. However, increased GAA content in rodents affected by guanidinoacetate methyltransferase (GAMT) deficiency might be responsible for their spared muscle function. Given these conflicting data, and lacking experimental evidence, we investigated whether GAA affected synaptic transmission in brain hippocampal slices. Incubation with 11.5 \ub5M GAA (the highest concentration in the cerebrospinal fluid of GAMT-deficient patients) did not change the postsynaptic compound action potential. Even 1 or 2 mM had no effect, while 4 mM caused a reversible decrease in the potential. Guanidinoacetate increased creatine and phosphocreatine, but not after blocking the creatine transporter (also used by GAA). In an attempt to allow the brain delivery of GAA when there was a creatine transporter deficiency, we synthesized diacetyl guanidinoacetic acid ethyl ester (diacetyl-GAAE), a lipophilic derivative. In brain slices, 0.1 mM did not cause electrophysiological changes and improved tissue viability after blockage of the creatine transporter. However, diacetyl-GAAE did not increase creatine nor phosphocreatine in brain slices after blockage of the creatine transporter. We conclude that: (1) upon acute administration, GAA is neither epileptogenic nor neurotoxic; (2) Diacetyl-GAAE improves tissue viability after blockage of the creatine transporter but not through an increase in creatine or phosphocreatine. Diacetyl-GAAE might give rise to a GAA\u2013phosphoGAA system that vicariates the missing creatine\u2013phosphocreatine system. Our in vitro data show that GAA supplementation may be safe in the short term, and that a lipophilic GAA prodrug may be useful in creatine transporter deficiency

Creatine salts provide neuroprotection even after partial impairment of the creatine transporter

open6Creatine, a compound that is critical for energy metabolism of nervous cells, crosses the blood-brain barrier (BBB) and the neuronal plasma membrane with difficulty, and only using its specific transporter. In the hereditary condition where the creatine transporter is defective (creatine transporter deficiency) there is no creatine in the brain, and administration of creatine is useless lacking the transporter. The disease is severe and incurable. Creatine-derived molecules that could cross BBB and plasma membrane independently of the transporter might be useful to cure this condition. Moreover, such molecules could be useful also in stroke and other brain ischemic conditions. In this paper, we investigated three creatine salts, creatine ascorbate, creatine gluconate and creatine glucose. Of these, creatine glucose was ineffective after transporter block with guanidine acetic acid (GPA) administration. Creatine ascorbate was not superior to creatine in increasing tissue creatine and phosphocreatine content after transporter impairment, however even after such impairment it delayed synaptic failure during anoxia. Finally, creatine gluconate was superior to creatine in increasing tissue content of creatine after transporter block and slowed down PS disappearance during anoxia, an effect that creatine did not have. These findings suggest that coupling creatine to molecules having a specific transporter may be a useful strategy in creatine transporter deficiency. In particular, creatine ascorbate has effects comparable to those of creatine in normal conditions, while being superior to it under conditions of missing or impaired creatine transporter.openAdriano, E; Garbati, P; Salis, A; Damonte, G; Millo, E; Balestrino, MAdriano, ENRICO GIOVANNI; Garbati, Patrizia; Salis, Annalisa; Damonte, Gianluca; Millo, Enrico; Balestrino, Maurizi

Fibrinogen αC‐regions are not directly involved in fibrin polymerization as evidenced by a "Double‐Detroit" recombinant fibrinogen mutant and knobs‐mimic peptides

Background: Fibrin polymerization, following fibrinopeptides A and B (FpA, FpB) cleavage, relies on newly exposed α‐ and β‐chains N‐termini (GPR, GHR; A‐, B‐knobs, respectively) engaging pre‐existent a and b pockets in other fibrin(ogen) molecules' γ‐ and (B)β‐chains C‐terminal regions. A role for mostly disordered (A)α‐chains C‐terminal regions "bridging" between fibrin molecules/fibrils has been proposed. Objectives: Fibrinogen Detroit is a clinically observed mutation (AαR19→S) with non‐engaging GPS A‐knobs. By analogy, a similar Bβ‐chain mutation, BβR17→S, should produce non‐engaging GHS B‐knobs. A homozygous “Double‐Detroit” mutant (AαR19→S, BβR17→S; DD‐FG) was developed: with A‐a and B‐b engagements endogenously blocked, other interactions would become apparent. Methods: DD‐FG, wild‐type recombinant (WT‐FG), and human plasma (hp‐FG) fibrinogen self‐association was studied by turbidimetry coupled with fibrinopeptides release HPLC/mass spectrometry analyses, and by light‐scattering following size‐exclusion chromatography (SE‐HPLC). Results: In contrast to WT‐FG and hp‐FG, DD‐FG produced no turbidity increase, irrespective of thrombin concentration. The SE‐HPLC profile of concentrated DD‐FG was unaffected by thrombin treatment, and light‐scattering, at lower concentration, showed no intensity and hydrodynamic radius changes. Compared with hp‐FG, both WT‐FG and DD‐FG showed no FpA cleavage difference, while ~50% FpB was not recovered. Correspondingly, SDS‐PAGE/Western‐blots revealed partial Bβ‐chain N‐terminal and Aα‐chain C‐terminal degradation. Nevertheless, ~70% DD‐FG molecules bearing (A)αC‐regions potentially able to associate were available. Higher‐concentration, nearly‐intact hp‐FG with 500‐fold molar excess GPRP‐NH2/GHRP‐NH2 knobs‐mimics experiments confirmed these no‐associations findings. Conclusions: (A)αC‐regions interactions appear too weak to assist native fibrin polymerization, at least without knobs engagement. Their role in all stages should be carefully reconsidered

Mechanical alloying of Hf and Fe powders

Pure crystalline Hf and Fe powders were mixed and milled under an argon atmosphere. The evolution of the system with milling time was followed with Mossbauer effect spectroscopy and X-ray diffraction. The results indicate that in the first stages an amorphous Fe-rich alloy was gradually formed together with a solid solution of Hf in Fe beyond the solubility limit.Facultad de Ciencias Exacta

Phytotoxic activity of Salvia x jamensis.

A study has been carried out on the surface exudate of Salvia x jamensis, which showed a significant phytotoxic activity against Papaver rhoeas L. and Avena sativa L.. Bioguided separation of the exudate yielded active fractions from which 3β-hydroxy-isopimaric acid (1), hautriwaic acid (2), betulinic acid (3), 7,8β-dihydrosalviacoccin (4), isopimaric acid (5), 14α-hydroxy-isopimaric acid (7), 15,16-epoxy-7α,10β-dihydroxy-clerod-3,13(16),14-trien-17,12;18,19-diolide (8), cirsiliol (5,3′,4′-trihydroxy-6,7-dimethoxyflavone, 9) and two new neoclerodane diterpenes (6 and 10) were isolated. The structures of 6 and 10 were identified as 15,16-epoxy-10β-hydroxy-clerod-3,13(16),14-trien-17,12;18,19-diolide and 15,16-epoxy-7α,10-dihydroxy-clerod-2,13(16),14-trien-17,12;18,19-diolide respectively on the basis of spectroscopic data analysis. All compounds, but 7, 8 and 10, were active in inhibiting the germination of the tested species

Overcoming Rooming-In Barriers : a Survey on Mothers' Perspectives

Background: The importance of rooming-in in promoting breastfeeding initiation and continuation within the 10 Steps for Successful Breastfeeding is widely acknowledged. However, adherence to this practice by healthcare facilities is lower than that of other Steps. A deeper knowledge of maternal rooming-in experience has been advocated to identify the most effective rooming-in policies, thus enabling mothers to have a positive experience when practicing it in the postpartum period. Aim: To investigate maternal knowledge of rooming-in and the most frequently encountered barriers and possible facilitators of adherence to the practice, according to their experience. Study Design and Methods: We enrolled mothers who delivered healthy term or late preterm infants during the month of January 2019 in a tertiary referral center for neonatal care in Milan, Italy. At discharge, a structured interview about mothers' rooming-in experience was administered by healthcare professionals. Basic subjects' characteristics and mode of feeding were recorded. Results: The enrolled population included 328 mothers and 333 neonates. The great majority of mothers knew of rooming-in and 48.2% practiced it continuously. The 86.3% of mothers was aware of the beneficial effects of rooming-in; promotion of mother-infant bonding, increased confidence in taking care of the baby and ability to recognize baby's feeding cues were the most frequently cited, whereas improving breastfeeding was reported by a limited number of mothers, unless they were asked a specific question about it. The main reported obstacles were fatigue (40.5%) and cesarean section related difficulties (15.5%); night was the most critical time of the day for rooming-in. Strategies suggested by mothers for improving rooming-in were increased assistance to the dyad, organizational and structural changes and the possibility to have a family member during the night. Additionally, mothers who adhered to rooming-in practice continuously during hospital stay had a higher exclusive breastfeeding rate at discharge compared to mothers who did not. Conclusions: Our study contributes to a deeper knowledge of maternal rooming-in experience in an Italian tertiary maternity. We underline the importance of providing a tailored support to the mother-infant dyad in order to overcome rooming-in barriers perceived by mothers and promote a positive rooming-in experience

Influence of seed layer thickness on properties of electrodeposited ZnO nanostructured films

The quality and properties of electrodeposited nanostructured ZnO films are improved when they are deposited on a crystal lattice-matching substrate. To this end, a highly conductive indium tin oxide substrate is covered with an interlayer of ZnO using direct-current magnetron sputtering. In this manuscript, we describe the effect of this interlayer on the morphological and optical properties of several nanostructured ZnO films grown by different electrodeposition methods. The thickness of the ZnO interlayer was varied starting from ultrathin layers of 10 nm all the way up to 230 nm as determined by ellipsometry. The structural and optical properties of the nanostructured ZnO films deposited on top of these interlayers were characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy and UV–visible spectroscopy. Optimum properties of the nanostructured ZnO films for application in thin-film optoelectronic devices are obtained when the ZnO interlayer has a thickness of approximately 45 nm. This is the case for all the electrodeposition methods used in this work.Facultad de Ciencias ExactasInstituto de Física La Plat