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391
result(s) for
"Valenzuela, Fernando"
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Efficient Use of Water in Tailings Management: New Technologies and Environmental Strategies for the Future of Mining
by
Valenzuela, Fernando
,
Cacciuttolo, Carlos
in
Desalination
,
Drinking water
,
Freshwater resources
2022
Nowadays, many major copper mining projects in desert areas with extremely dry climates, as in northern Chile and the southern coast of Peru, process sulfide ores at high production rates; in some cases over 100,000 metric tonnes per day (mtpd), generating large amounts of tailings, that are commonly managed and transported to tailings storage facilities (TSF) hydraulically using fresh water. Considering the extremely dry climate, water scarcity, community demands, and environmental constraints in these desert areas, the efficient use of water in mining is being strongly enforced. For this reason, water supply is recognized as one of the limiting factors for the development of new mining projects and for the expansion of the existing ones in these areas. New water supply alternatives, such as sea water desalinization, direct use of sea water, or water recovery from tailings, represent the strategy developed by the mining industry to deal with this growing scarcity. The focus of this paper is the possibility of applying different water supply technologies or a combination of these, implementing improved water management strategies that consider: environmental issues, technical issues, stringent regulatory frameworks, community requests and cost-effective strategies, that result in a reduction of freshwater make-up water requirements for mining (m3 per metric tonnes of treated ore).
Journal Article
Enhancement of parvalbumin interneuron-mediated neurotransmission in the retrosplenial cortex of adolescent mice following third trimester-equivalent ethanol exposure
by
Barber, Megan J.
,
Valenzuela, C. Fernando
,
Chavez, Glenna J.
in
631/154/436/2387
,
631/378/1689/2608
,
631/378/1934
2021
Prenatal ethanol exposure causes a variety of cognitive deficits that have a persistent impact on quality of life, some of which may be explained by ethanol-induced alterations in interneuron function. Studies from several laboratories, including our own, have demonstrated that a single binge-like ethanol exposure during the equivalent to the third trimester of human pregnancy leads to acute apoptosis and long-term loss of interneurons in the rodent retrosplenial cortex (RSC). The RSC is interconnected with the hippocampus, thalamus, and other neocortical regions and plays distinct roles in visuospatial processing and storage, as well as retrieval of hippocampal-dependent episodic memories. Here we used slice electrophysiology to characterize the acute effects of ethanol on GABAergic neurotransmission in the RSC of neonatal mice, as well as the long-term effects of neonatal ethanol exposure on parvalbumin-interneuron mediated neurotransmission in adolescent mice. Mice were exposed to ethanol using vapor inhalation chambers. In postnatal day (P) 7 mouse pups, ethanol unexpectedly failed to potentiate GABA
A
receptor-mediated synaptic transmission. Binge-like ethanol exposure of P7 mice expressing channel rhodopsin in parvalbumin-positive interneurons enhanced the peak amplitudes, asynchronous activity and total charge, while decreasing the rise-times of optically-evoked GABA
A
receptor-mediated inhibitory postsynaptic currents in adolescent animals. These effects could partially explain the learning and memory deficits that have been documented in adolescent and young adult mice exposed to ethanol during the third trimester-equivalent developmental period.
Journal Article
X-linked neonatal-onset epileptic encephalopathy associated with a gain-of-function variant p.R660T in GRIA3
by
Ayala Valenzuela, Fernando Eduardo
,
Thorpe, Erin
,
Masser-Frye, Diane
in
Biology and Life Sciences
,
Cell receptors
,
Cerebellum
2021
The X-linked GRIA3 gene encodes the GLUA3 subunit of AMPA-type glutamate receptors. Pathogenic variants in this gene were previously reported in neurodevelopmental diseases, mostly in male patients but rarely in females. Here we report a de novo pathogenic missense variant in GRIA3 (c.1979G>C; p. R660T) identified in a 1-year-old female patient with severe epilepsy and global developmental delay. When exogenously expressed in human embryonic kidney (HEK) cells, GLUA3_R660T showed slower desensitization and deactivation kinetics compared to wildtype (wt) GLUA3 receptors. Substantial non-desensitized currents were observed with the mutant but not for wt GLUA3 with prolonged exposure to glutamate. When co-expressed with GLUA2, the decay kinetics were similarly slowed in GLUA2/A3_R660T with non-desensitized steady state currents. In cultured cerebellar granule neurons, miniature excitatory postsynaptic currents (mEPSCs) were significantly slower in R660T transfected cells than those expressing wt GLUA3. When overexpressed in hippocampal CA1 neurons by in utero electroporation, the evoked EPSCs and mEPSCs were slower in neurons expressing R660T mutant compared to those expressing wt GLUA3. Therefore our study provides functional evidence that a gain of function (GoF) variant in GRIA3 may cause epileptic encephalopathy and global developmental delay in a female subject by enhancing synaptic transmission.
Journal Article
Tofacitinib versus etanercept or placebo in moderate-to-severe chronic plaque psoriasis: a phase 3 randomised non-inferiority trial
by
Valenzuela, Fernando
,
van de Kerkhof, Peter C M
,
Tawadrous, Margaret
in
Adult
,
Anti-Inflammatory Agents, Non-Steroidal
,
Anti-Inflammatory Agents, Non-Steroidal - therapeutic use
2015
New therapeutic options are needed for patients with psoriasis. Tofacitinib, an oral Janus kinase inhibitor, is being investigated as a treatment for moderate-to-severe chronic plaque psoriasis. In this study, we aimed to compare two tofacitinib doses with high-dose etanercept or placebo in this patient population.
In this phase 3, randomised, multicentre, double-dummy, placebo-controlled, 12-week, non-inferiority trial, adult patients with chronic stable plaque psoriasis (for ≥12 months) who were candidates for systemic or phototherapy and had a Psoriasis Area and Severity Index (PASI) score of 12 or higher and a Physician's Global Assessment (PGA) of moderate or severe, and had failed to respond to, had a contraindication to, or were intolerant to at least one conventional systemic therapy, were enrolled from 122 investigational dermatology centres worldwide. Eligible patients were randomly assigned in a 3:3:3:1 ratio to receive tofacitinib 5 mg or 10 mg twice daily at about 12 h intervals, etanercept 50 mg subcutaneously twice weekly at about 3–4 day intervals, or placebo. Randomisation was done by a computer-generated randomisation schedule, and all patients and study personnel were masked to treatment assignment. The co-primary endpoints were the proportion of patients at week 12 with at least a 75% reduction in the PASI score from baseline (PASI75 response) and the proportion of patients achieving a PGA score of “clear” or “almost clear” (PGA response), analysed in the full analysis set (all patients who were randomised and received at least one dose of study drug). This study is registered with ClinicalTrials.gov, number NCT01241591.
Between Nov 29, 2010, and Sept 13, 2012, we enrolled 1106 eligible adult patients with chronic plaque psoriasis and randomly assigned them to the four treatment groups (330 to tofacitinib 5 mg twice daily, 332 to tofacitinib 10 mg twice daily, 336 to etanercept 50 mg twice weekly, and 108 to placebo). Of these patients, 1101 actually received their assigned study medication (329 in the tofactinib 5 mg group, 330 in the tofacitinib 10 mg group, 335 in the etanercept group, and 107 in the placebo group). At week 12, PASI75 responses were recorded in 130 (39·5%) of 329 patients in the tofacitinib 5 mg group, 210 (63·6%) of 330 in the tofacitinib 10 mg group, 197 (58·8%) of 335 in the etanercept group, and six (5·6%) of 107 in the placebo group. A PGA response was achieved by 155 (47·1%) of 329 patients in the tofacitinib 5 mg group, 225 (68·2%) of 330 in the tofacitinib 10 mg group, 222 (66·3%) of 335 in the etanercept group, and 16 (15·0%) of 107 in the placebo group. The rate of adverse events was similar across the four groups, with serious adverse events occurring in seven (2%) of 329 patients in the tofacitinib 5 mg group, five (2%) of 330 in the tofacitinib 10 mg group, seven (2%) of 335 in the etanercept group, and two (2%) of 107 in the placebo group. Three (1%) of 329 patients in the tofacitinib 5 mg group, ten (3%) of 330 in the tofacitinib 10 mg group, 11 (3%) of 335 in the etanercept group, and four (4%) of 107 patients in the placebo group discontinued their assigned treatment because of adverse events.
In patients with moderate-to-severe plaque psoriasis, the 10 mg twice daily dose of tofacitinib was non-inferior to etanercept 50 mg twice weekly and was superior to placebo, but the 5 mg twice daily dose did not show non-inferiority to etanercept 50 mg twice weekly. The adverse event rates over 12 weeks were similar for tofacitinib and etanercept. This study indicates that in the future tofacitinib could provide a convenient and well-tolerated therapeutic option for patients with moderate-to-severe plaque psoriasis.
Pfizer Inc.
Journal Article
Primary architecture and energy requirements of Type III and Type IV secretion systems
by
Valenzuela-Gómez, Fernando
,
Cabezón, Elena
,
Arechaga, Ignacio
in
Adenosine Triphosphatases
,
ATPases
,
Bacteria
2023
Many pathogens use Type III and Type IV protein secretion systems to secrete virulence factors from the bacterial cytosol into host cells. These systems operate through a one-step mechanism. The secreted substrates (protein or nucleo-protein complexes in the case of Type IV conjugative systems) are guided to the base of the secretion channel, where they are directly delivered into the host cell in an ATP-dependent unfolded state. Despite the numerous disparities between these secretion systems, here we have focused on the structural and functional similarities between both systems. In particular, on the structural similarity shared by one of the main ATPases (EscN and VirD4 in Type III and Type IV secretion systems, respectively). Interestingly, these ATPases also exhibit a structural resemblance to F 1 -ATPases, which suggests a common mechanism for substrate secretion. The correlation between structure and function of essential components in both systems can provide significant insights into the molecular mechanisms involved. This approach is of great interest in the pursuit of identifying inhibitors that can effectively target these systems.
Journal Article
Mini-Review: Effects of Ethanol on GABAA Receptor-Mediated Neurotransmission in the Cerebellar Cortex—Recent Advances
2015
Studies from several laboratories have shown that ethanol impairs cerebellar function, in part, by altering GABAergic transmission. Here, we discuss recent advances in our understanding of the acute effects of ethanol on GABA
A
receptor-mediated neurotransmission at cerebellar cortical circuits, mainly focusing on electrophysiological studies with slices from laboratory animals. These studies have shown that acute ethanol exposure increases GABA release at molecular layer interneuron-to-Purkinje cell synapses and also at reciprocal synapses between molecular layer interneurons. In granule cells, studies with rat cerebellar slices have consistently shown that acute ethanol exposure both potentiates tonic currents mediated by extrasynaptic GABA
A
receptors and also increases the frequency of spontaneous inhibitory postsynaptic currents mediated by synaptic GABA
A
receptors. These effects have been also documented in some granule cells from mice and nonhuman primates. Currently, there are two distinct models on how ethanol produces these effects. In one model, ethanol primarily acts by directly potentiating extrasynaptic GABA
A
receptors, including a population that excites granule cell axons and stimulates glutamate release onto Golgi cells. In the other model, ethanol acts indirectly by increasing spontaneous Golgi cell firing via inhibition of the Na
+
/K
+
ATPase, a quinidine-sensitive K
+
channel, and neuronal nitric oxide synthase. It was also demonstrated that a direct inhibitory effect of ethanol on tonic currents can be unmasked under conditions of low protein kinase C activity. In the last section, we briefly discuss studies on the chronic effect of ethanol on cerebellar GABA
A
receptor-mediated transmission and highlight potential areas where future research is needed.
Journal Article
Moderate prenatal alcohol exposure alters the number and function of GABAergic interneurons in the murine orbitofrontal cortex
by
Kenton, Johnny A.
,
Ontiveros, Tiahna
,
Valenzuela, C. Fernando
in
Alcohol
,
Alcohol use
,
Animal cognition
2020
Exposure to alcohol during development produces Fetal Alcohol Spectrum Disorders (FASD), characterized by a wide range of effects that include deficits in multiple cognitive domains. Early identification and treatment of individuals with FASD remain a challenge because neurobehavioral alterations do not become a significant problem until late childhood and early adolescence. Understanding the mechanisms underlying low and moderate prenatal alcohol exposure (PAE) effects on behavior and cognition is essential for improved diagnosis and treatment. Here, we examined the functional and morphological changes in an area known to be involved in executive control, the orbitofrontal cortex (OFC). We found that a moderate PAE model, previously shown to impair behavioral flexibility and to alter OFC activity in vivo, produced moderate functional and morphological changes within the OFC of mice in vitro. Specifically, slice electrophysiological recordings of spontaneous inhibitory post-synaptic currents in OFC pyramidal neurons revealed a significant increase in the amplitude and area in PAE mice relative to controls. Immunohistochemistry uncovered an increase in calretinin-, but not somatostatin- or parvalbumin-expressing cortical interneurons in the OFC of PAE mice. Together, these data suggest that moderate prenatal alcohol exposure alters the disinhibitory function in the OFC, which may contribute to the executive function deficits associated with FASD.
•Moderate PAE alters GABAergic tone in the OFC.•Female saccharine-control mice have fewer inhibitory interneurons in the OFC.•Axosomatic, PV+ and axodendritic, SST+ interneurons are similar in population size in the OFC between both PAE and SAC mice.•Disinhibitory, calretinin-expressing interneurons are increased following PAE, particularly in females.•Further evidence that PAE affects GABAergic interneurons in cortical areas involved in aspects of executive control.
Journal Article
Epibiotic bacterial community composition varies during different developmental stages of Octopus mimus: Study of cultivable representatives and their secondary metabolite production
by
Valenzuela, Fernando
,
Alcayaga, Valezka
,
Bórquez, Jorge
in
Algae
,
Animals
,
Anti-Bacterial Agents - pharmacology
2024
Marine microbial communities colonizing the skin of invertebrates constitute the primary barrier between host and environment, potentially exerting beneficial, neutral, or detrimental effects on host fitness. To evaluate the potential contribution of epibiotic bacteria to the survival of early developmental stages of Octopus mimus , bacterial isolates were obtained from eggs, paralarvae, and adults. Their enzymatic activities were determined, and antibacterial properties were assessed against common marine pathogens. The isolates belonged to the phyla Proteobacteria, Actinomycetota, Bacteroidota, and Bacillota, represented by 21 genera and 27 species. Specific taxa were associated with each developmental stage, with only three species shared among different stages: Bacillus pumilus , B . megaterium , and Shewanella algae , which also inhibited the growth of all assayed pathogens. Organic extracts from Bacillus megaterium M8-1 were obtained, and UHPLC-MS analysis detected seventeen putative compounds, including two phenolic acids, three indole derivatives, and twelve oxylipins. Our findings provide novel data on cultivable bacterial representatives isolated from Octopus mimus capable of synthesizing chemical compounds with bioactive properties. These results contribute to a better understanding of the role of microbial communities in the survival of this invertebrate species during critical early life stages.
Journal Article
Alcohol Exposure Decreases CREB Binding Protein Expression and Histone Acetylation in the Developing Cerebellum
by
Guo, Weixiang
,
Valenzuela, C. Fernando
,
Zhang, Li
in
Acetates
,
Acetylation
,
Acetylation - drug effects
2011
Fetal alcohol exposure affects 1 in 100 children making it the leading cause of mental retardation in the US. It has long been known that alcohol affects cerebellum development and function. However, the underlying molecular mechanism is unclear.
We demonstrate that CREB binding protein (CBP) is widely expressed in granule and Purkinje neurons of the developing cerebellar cortex of naïve rats. We also show that exposure to ethanol during the 3(rd) trimester-equivalent of human pregnancy reduces CBP levels. CBP is a histone acetyltransferase, a component of the epigenetic mechanism controlling neuronal gene expression. We further demonstrate that the acetylation of both histone H3 and H4 is reduced in the cerebellum of ethanol-treated rats.
These findings indicate that ethanol exposure decreases the expression and function of CBP in the developing cerebellum. This effect of ethanol may be responsible for the motor coordination deficits that characterize fetal alcohol spectrum disorders.
Journal Article
The Science and Evolutionary Perspective of Beautiful Skin
by
Valenzuela, Fernando
,
Retamal, Catalina
,
Hartmann, Dan
in
Aesthetics
,
Animal reproduction
,
Beauty
2025
Quality skin has long been a symbol of health and attractiveness, reflecting both genetic and environmental influences. Multiple elements contribute to beautiful skin. This complex topic influences modern dermatological practices and skincare approaches. This article reviews and explores the characteristics that define beautiful skin, integrating physical attributes with the scientific foundations that underpin them. It also delves into the evolutionary significance of skin appearance and the impact of visible skin conditions on social and psychological well-being. Additionally, it reviews advances in dermatological treatments and preventive measures aimed at achieving beautiful skin.
Journal Article