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1.
Philos Trans R Soc Lond B Biol Sci ; 379(1902): 20230015, 2024 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-38583468

RESUMEN

Expanding and managing current habitat and species protection measures is at the heart of the European biodiversity strategy. A structured approach is needed to gain insights into such issues is systematic conservation planning, which uses techniques from decision theory to identify places and actions that contribute most effectively to policy objectives given a set of constraints. Yet culturally and historically determined European landscapes make the implementation of any conservation plans challenging, requiring an analysis of synergies and trade-offs before implementation. In this work, we review the scientific literature for evidence of previous conservation planning approaches, highlighting recent advances and success stories. We find that the conceptual characteristics of European conservation planning studies likely reduced their potential in contributing to better-informed decisions. We outline pathways towards improving the uptake of decision theory and multi-criteria conservation planning at various scales, particularly highlighting the need for (a) open data and intuitive tools, (b) the integration of biodiversity-focused conservation planning with multiple objectives, (c) accounting of dynamic ecological processes and functions, and (d) better facilitation of entry-points and co-design practices of conservation planning scenarios with stakeholders. By adopting and improving these practices, European conservation planning might become more actionable and adaptable towards implementable policy outcomes. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Conservación de los Recursos Naturales/métodos , Biodiversidad , Europa (Continente)
3.
Bull Math Biol ; 85(10): 95, 2023 09 04.
Artículo en Inglés | MEDLINE | ID: mdl-37665428

RESUMEN

Existing methods for optimal control struggle to deal with the complexity commonly encountered in real-world systems, including dimensionality, process error, model bias and data heterogeneity. Instead of tackling these system complexities directly, researchers have typically sought to simplify models to fit optimal control methods. But when is the optimal solution to an approximate, stylized model better than an approximate solution to a more accurate model? While this question has largely gone unanswered owing to the difficulty of finding even approximate solutions for complex models, recent algorithmic and computational advances in deep reinforcement learning (DRL) might finally allow us to address these questions. DRL methods have to date been applied primarily in the context of games or robotic mechanics, which operate under precisely known rules. Here, we demonstrate the ability for DRL algorithms using deep neural networks to successfully approximate solutions (the "policy function" or control rule) in a non-linear three-variable model for a fishery without knowing or ever attempting to infer a model for the process itself. We find that the reinforcement learning agent discovers a policy that outperforms both constant escapement and constant mortality policies-the standard family of policies considered in fishery management. This DRL policy has the shape of a constant escapement policy whose escapement values depend on the stock sizes of other species in the model.


Asunto(s)
Conceptos Matemáticos , Modelos Biológicos , Algoritmos , Explotaciones Pesqueras , Aprendizaje
4.
Nat Hum Behav ; 7(11): 1869-1877, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37679441

RESUMEN

Historic segregation and inequality are critical to understanding modern environmental conditions. Race-based zoning policies, such as redlining in the United States during the 1930s, are associated with racial inequity and adverse multigenerational socioeconomic levels in income and education, and disparate environmental characteristics including tree canopy cover across urban neighbourhoods. Here we quantify the association between redlining and bird biodiversity sampling density and completeness-two critical metrics of biodiversity knowledge-across 195 cities in the United States. We show that historically redlined neighbourhoods remain the most undersampled urban areas for bird biodiversity today, potentially impacting conservation priorities and propagating urban environmental inequities. The disparity in sampling across redlined neighbourhood grades increased by 35.6% over the past 20 years. We identify specific urban areas in need of increased bird biodiversity sampling and discuss possible strategies for reducing uncertainty and increasing equity of sampling of biodiversity in urban areas. Our findings highlight how human behaviour and past social, economic and political conditions not just segregate our built environment but may also leave a lasting mark on the digital information we have about urban biodiversity.


Asunto(s)
Biodiversidad , Características de la Residencia , Estados Unidos , Humanos , Animales , Ciudades , Clase Social , Aves
5.
J Registry Manag ; 50(2): 67-68, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37575556
6.
Philos Trans R Soc Lond B Biol Sci ; 378(1881): 20220195, 2023 07 17.
Artículo en Inglés | MEDLINE | ID: mdl-37246377

RESUMEN

From out-competing grandmasters in chess to informing high-stakes healthcare decisions, emerging methods from artificial intelligence are increasingly capable of making complex and strategic decisions in diverse, high-dimensional and uncertain situations. But can these methods help us devise robust strategies for managing environmental systems under great uncertainty? Here we explore how reinforcement learning (RL), a subfield of artificial intelligence, approaches decision problems through a lens similar to adaptive environmental management: learning through experience to gradually improve decisions with updated knowledge. We review where RL holds promise for improving evidence-informed adaptive management decisions even when classical optimization methods are intractable and discuss technical and social issues that arise when applying RL to adaptive management problems in the environmental domain. Our synthesis suggests that environmental management and computer science can learn from one another about the practices, promises and perils of experience-based decision-making. This article is part of the theme issue 'Detecting and attributing the causes of biodiversity change: needs, gaps and solutions'.


Asunto(s)
Inteligencia Artificial , Toma de Decisiones , Política Ambiental , Aprendizaje Profundo , Algoritmos , Cambio Climático
7.
Psychiatr Serv ; 74(10): 1037-1044, 2023 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-36987707

RESUMEN

OBJECTIVE: Peer workers are widely employed across the mental health sector in Australia, and these positions increasingly include people with experience as a service user (consumer peer workers) and people with experience as a family member (caregiver peer workers). The authors explored similarities and differences between the consumer and caregiver peer workforces and considered positions designed to combine consumer and caregiver perspectives. METHODS: A mixed-methods design was used to analyze data from a nationwide Australian survey (N=882), including responses from peer staff with consumer and caregiver perspectives (N=558), and from mental health staff not designated as peer workers (N=324). RESULTS: Most participants viewed the two perspectives as different in terms of values or goals (51%) and work practices (59%), with fewer stating that the two workforces had similar goals or values (45%) and work practices (37%). Qualitative findings provided insight into these differences and similarities, identifying differences in perspectives, priorities, and work practices but highlighting similarities in values between the two workforces. Qualitative data also revealed potential risks of employing peer workers in roles designed to use both kinds of experience for direct support roles but indicated potential for the combined perspective in other contexts. Both qualitative and quantitative data indicated that participants with consumer experience perceived greater differences between the role types than those with caregiver experience only. CONCLUSIONS: The findings indicate similarities and differences between staff with consumer or caregiver perspectives and highlight the need for greater role clarity and the potential for conflict in positions where peer workers combine both perspectives.


Asunto(s)
Trastornos Mentales , Servicios de Salud Mental , Humanos , Salud Mental , Cuidadores , Australia , Grupo Paritario
8.
Regul Toxicol Pharmacol ; 138: 105309, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36481280

RESUMEN

Virtual Control Groups (VCGs) based on Historical Control Data (HCD) in preclinical toxicity testing have the potential to reduce animal usage. As a case study we retrospectively analyzed the impact of replacing Concurrent Control Groups (CCGs) with VCGs on the treatment-relatedness of 28 selected histopathological findings reported in either rat or dog in the eTOX database. We developed a novel methodology whereby statistical predictions of treatment-relatedness using either CCGs or VCGs of varying covariate similarity to CCGs were compared to designations from original toxicologist reports; and changes in agreement were used to quantify changes in study outcomes. Generally, the best agreement was achieved when CCGs were replaced with VCGs with the highest level of similarity; the same species, strain, sex, administration route, and vehicle. For example, balanced accuracies for rat findings were 0.704 (predictions based on CCGs) vs. 0.702 (predictions based on VCGs). Moreover, we identified covariates which resulted in poorer identification of treatment-relatedness. This was related to an increasing incidence rate divergence in HCD relative to CCGs. Future databases which collect data at the individual animal level including study details such as animal age and testing facility are required to build adequate VCGs to accurately identify treatment-related effects.


Asunto(s)
Pruebas de Toxicidad , Ratas , Animales , Perros , Estudios Retrospectivos , Grupos Control , Bases de Datos Factuales
9.
Regul Toxicol Pharmacol ; 138: 105308, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36481279

RESUMEN

Preclinical inter-species concordance can increase the predictivity of observations to the clinic, potentially reducing drug attrition caused by unforeseen adverse events. We quantified inter-species concordance of histopathological findings and target organ toxicities across four preclinical species in the eTOX database using likelihood ratios (LRs). This was done whilst only comparing findings between studies with similar compound exposure (Δ|Cmax| ≤ 1 log-unit), repeat-dosing duration, and animals of the same sex. We discovered 24 previously unreported significant inter-species associations between histopathological findings encoded by the HPATH ontology. More associations with strong positive concordance (33% LR+ > 10) relative to strong negative concordance (12.5% LR- < 0.1) were identified. Of the top 10 most positively concordant associations, 60% were computed between different histopathological findings indicating potential differences in inter-species pathogenesis. We also observed low inter-species target organ toxicity concordance. For example, liver toxicity concordance in short-term studies between female rats and dogs observed an average LR+ of 1.84, and an average LR- of 0.73. This was corroborated by similarly low concordance between rodents and non-rodents for 75 candidate drugs in AstraZeneca. This work provides new statistically significant associations between preclinical species, but finds that concordance is rare, particularly between the absence of findings.


Asunto(s)
Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Animales , Femenino , Ratas , Perros , Bases de Datos Factuales , Proyectos de Investigación
10.
J Immunother Cancer ; 10(4)2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35387780

RESUMEN

BACKGROUND: The Regulatory T cell (Treg) lineage is defined by the transcription factor FOXP3, which controls immune-suppressive gene expression profiles. Tregs are often recruited in high frequencies to the tumor microenvironment where they can suppress antitumor immunity. We hypothesized that pharmacological inhibition of FOXP3 by systemically delivered, unformulated constrained ethyl-modified antisense oligonucleotides could modulate the activity of Tregs and augment antitumor immunity providing therapeutic benefit in cancer models and potentially in man. METHODS: We have identified murine Foxp3 antisense oligonucleotides (ASOs) and clinical candidate human FOXP3 ASO AZD8701. Pharmacology and biological effects of FOXP3 inhibitors on Treg function and antitumor immunity were tested in cultured Tregs and mouse syngeneic tumor models. Experiments were controlled by vehicle and non-targeting control ASO groups as well as by use of multiple independent FOXP3 ASOs. Statistical significance of biological effects was evaluated by one or two-way analysis of variance with multiple comparisons. RESULTS: AZD8701 demonstrated a dose-dependent knockdown of FOXP3 in primary Tregs, reduction of suppressive function and efficient target downregulation in humanized mice at clinically relevant doses. Surrogate murine FOXP3 ASO, which efficiently downregulated Foxp3 messenger RNA and protein levels in primary Tregs, reduced Treg suppressive function in immune suppression assays in vitro. FOXP3 ASO promoted more than 70% reduction in FOXP3 levels in Tregs in vitro and in vivo, strongly modulated Treg effector molecules (eg, ICOS, CTLA-4, CD25 and 4-1BB), and augmented CD8+ T cell activation and produced antitumor activity in syngeneic tumor models. The combination of FOXP3 ASOs with immune checkpoint blockade further enhanced antitumor efficacy. CONCLUSIONS: Antisense inhibitors of FOXP3 offer a promising novel cancer immunotherapy approach. AZD8701 is being developed clinically as a first-in-class FOXP3 inhibitor for the treatment of cancer currently in Ph1a/b clinical trial (NCT04504669).


Asunto(s)
Neoplasias , Oligonucleótidos Antisentido , Animales , Modelos Animales de Enfermedad , Factores de Transcripción Forkhead/genética , Factores de Transcripción Forkhead/metabolismo , Humanos , Terapia de Inmunosupresión , Inmunoterapia , Ratones , Neoplasias/tratamiento farmacológico , Neoplasias/genética , Linfocitos T Reguladores , Microambiente Tumoral
11.
Ecol Appl ; 32(4): e2578, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35191110

RESUMEN

The ocean's mesopelagic zone (200-1000 m) remains one of the most understudied parts of the ocean despite knowledge that mesopelagic fishes are highly abundant. Apex predators from the surface waters are known to consume these fishes, constituting an important ecological interaction. Some countries have begun exploring the potential harvest of mesopelagic fishes to supply fishmeal and fish oil markets due to the high fish abundance in the mesopelagic zone compared with overfished surface waters. This study explored the economic and ecological implications of a moratorium on the harvest of mesopelagic fishes such as lanternfish off the US West Coast, one of the few areas where such resources are managed. We adapted a bioeconomic decision model to examine the tradeoffs between the values gained from a hypothetical mesopelagic fishery with the potential values lost from declines in predators of mesopelagic fishes facing a reduced prey resource. The economic rationale for a moratorium on harvesting mesopelagics was sensitive both to ecological relationships and the scale of the nonmarket values attributed to noncommercial predators. Using a California Current-based ecological simulation model, we found that most modeled predators of mesopelagic fishes increased in biomass even under high mesopelagic harvest rates, but the changes (either increases or decreases) were small, with relatively few predators responding with more than a 10% change in their biomass. While the ecological simulations implied that a commercial mesopelagic fishery might not have large biomass impacts for many species in the California Current system, there is still a need to further explore the various roles of the mesopelagic zone in the ocean.


Asunto(s)
Ecosistema , Explotaciones Pesqueras , Animales , Biomasa , Conservación de los Recursos Naturales , Peces , Modelos Teóricos
12.
Glob Chang Biol ; 27(23): 6025-6058, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34636101

RESUMEN

Land-based climate mitigation measures have gained significant attention and importance in public and private sector climate policies. Building on previous studies, we refine and update the mitigation potentials for 20 land-based measures in >200 countries and five regions, comparing "bottom-up" sectoral estimates with integrated assessment models (IAMs). We also assess implementation feasibility at the country level. Cost-effective (available up to $100/tCO2 eq) land-based mitigation is 8-13.8 GtCO2 eq yr-1 between 2020 and 2050, with the bottom end of this range representing the IAM median and the upper end representing the sectoral estimate. The cost-effective sectoral estimate is about 40% of available technical potential and is in line with achieving a 1.5°C pathway in 2050. Compared to technical potentials, cost-effective estimates represent a more realistic and actionable target for policy. The cost-effective potential is approximately 50% from forests and other ecosystems, 35% from agriculture, and 15% from demand-side measures. The potential varies sixfold across the five regions assessed (0.75-4.8 GtCO2eq yr-1 ) and the top 15 countries account for about 60% of the global potential. Protection of forests and other ecosystems and demand-side measures present particularly high mitigation efficiency, high provision of co-benefits, and relatively lower costs. The feasibility assessment suggests that governance, economic investment, and socio-cultural conditions influence the likelihood that land-based mitigation potentials are realized. A substantial portion of potential (80%) is in developing countries and LDCs, where feasibility barriers are of greatest concern. Assisting countries to overcome barriers may result in significant quantities of near-term, low-cost mitigation while locally achieving important climate adaptation and development benefits. Opportunities among countries vary widely depending on types of land-based measures available, their potential co-benefits and risks, and their feasibility. Enhanced investments and country-specific plans that accommodate this complexity are urgently needed to realize the large global potential from improved land stewardship.


Asunto(s)
Cambio Climático , Ecosistema , Agricultura , Estudios de Factibilidad , Políticas
13.
Glob Chang Biol ; 26(8): 4357-4365, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32301542

RESUMEN

While improved management of agricultural landscapes is promoted as a promising natural climate solution, available estimates of the mitigation potential are based on coarse assessments of both agricultural extent and aboveground carbon density. Here we combine 30 meter resolution global maps of aboveground woody carbon, tree cover, and cropland extent, as well as a 1 km resolution map of global pasture land, to estimate the current and potential carbon storage of trees in nonforested portions of agricultural lands. We find that global croplands currently store 3.07 Pg of carbon (C) in aboveground woody biomass (i.e., trees) and pasture lands account for an additional 3.86 Pg C across a combined 3.76 billion ha. We then estimate the climate mitigation potential of multiple scenarios of integration and avoided loss of trees in crop and pasture lands based on region-specific biomass distributions. We evaluate our findings in the context of nationally determined contributions and find that the majority of potential carbon storage from integration and avoided loss of trees in crop and pasture lands is in countries that do not identify agroforestry as a climate mitigation technique.


Asunto(s)
Agricultura , Árboles , Biomasa , Carbono , Clima
14.
Regul Toxicol Pharmacol ; 113: 104624, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32126256

RESUMEN

An international expert working group representing 37 organisations (pharmaceutical/biotechnology companies, contract research organisations, academic institutions and regulatory bodies) collaborated in a data sharing exercise to evaluate the utility of two species within regulatory general toxicology studies. Anonymised data on 172 drug candidates (92 small molecules, 46 monoclonal antibodies, 15 recombinant proteins, 13 synthetic peptides and 6 antibody-drug conjugates) were submitted by 18 organisations. The use of one or two species across molecule types, the frequency for reduction to a single species within the package of general toxicology studies, and a comparison of target organ toxicities identified in each species in both short and longer-term studies were determined. Reduction to a single species for longer-term toxicity studies, as used for the development of biologicals (ICHS6(R1) guideline) was only applied for 8/133 drug candidates, but might have been possible for more, regardless of drug modality, as similar target organ toxicity profiles were identified in the short-term studies. However, definition and harmonisation around the criteria for similarity of toxicity profiles is needed to enable wider consideration of these principles. Analysis of a more robust dataset would be required to provide clear, evidence-based recommendations for expansion of these principles to small molecules or other modalities where two species toxicity testing is currently recommended.


Asunto(s)
Desarrollo de Medicamentos , Evaluación Preclínica de Medicamentos/efectos adversos , Pruebas de Toxicidad , Animales , Bases de Datos Factuales , Humanos , Medición de Riesgo
15.
Philos Trans R Soc Lond B Biol Sci ; 375(1794): 20190126, 2020 03 16.
Artículo en Inglés | MEDLINE | ID: mdl-31983330

RESUMEN

Better land stewardship is needed to achieve the Paris Agreement's temperature goal, particularly in the tropics, where greenhouse gas emissions from the destruction of ecosystems are largest, and where the potential for additional land carbon storage is greatest. As countries enhance their nationally determined contributions (NDCs) to the Paris Agreement, confusion persists about the potential contribution of better land stewardship to meeting the Agreement's goal to hold global warming below 2°C. We assess cost-effective tropical country-level potential of natural climate solutions (NCS)-protection, improved management and restoration of ecosystems-to deliver climate mitigation linked with sustainable development goals (SDGs). We identify groups of countries with distinctive NCS portfolios, and we explore factors (governance, financial capacity) influencing the feasibility of unlocking national NCS potential. Cost-effective tropical NCS offers globally significant climate mitigation in the coming decades (6.56 Pg CO2e yr-1 at less than 100 US$ per Mg CO2e). In half of the tropical countries, cost-effective NCS could mitigate over half of national emissions. In more than a quarter of tropical countries, cost-effective NCS potential is greater than national emissions. We identify countries where, with international financing and political will, NCS can cost-effectively deliver the majority of enhanced NDCs while transforming national economies and contributing to SDGs. This article is part of the theme issue 'Climate change and ecosystems: threats, opportunities and solutions'.


Asunto(s)
Cambio Climático , Conservación de los Recursos Naturales/legislación & jurisprudencia , Ecosistema , Política Ambiental/legislación & jurisprudencia , Calentamiento Global/prevención & control , Calentamiento Global/legislación & jurisprudencia , Regulación Gubernamental
16.
J Exp Child Psychol ; 189: 104695, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31605899

RESUMEN

Children judge in-group members more favorably than out-group members. They also judge moral transgressions as more serious and more worthy of punishment than conventional transgressions. Here we asked whether children's judgments of moral and conventional transgressions vary by the group membership of the transgressor (in-group, neutral, out-group, or self). In addition, we asked whether judgments of the transgressions would extend to the transgressors themselves, including cases in which the self was the transgressor. Results show that transgressions committed by out-group members were judged as being more serious and more punish-worthy than those committed by members of other groups. In addition, children judged out-group transgressors more harshly, and the self more leniently, than other group members. Overall, results suggest that group membership does affect judgments of transgressions and transgressors, with out-group members consistently judged the most negatively and the self consistently judged the least negatively. However, when judging the transgressor or the seriousness of the transgression, domain distinctions do persist even as group membership varies. Although, when assigning punishment, domain distinctions persist only when judging the transgressions of out-group members and neutral individuals. These findings demonstrate the powerful effect of group membership on the judgments of both acts and actors, indicating that when judging transgressions children consider not only the moral or conventional status of the act but also the group membership of the actor.


Asunto(s)
Juicio , Principios Morales , Identificación Social , Afecto , Niño , Preescolar , Femenino , Humanos , Masculino , Autoevaluación (Psicología)
17.
Sci Adv ; 4(6): eaat1719, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-29938225

RESUMEN

Poor survival rates of patients with tumors arising from or disseminating into the brain are attributed to an inability to excise all tumor tissue (if operable), a lack of blood-brain barrier (BBB) penetration of chemotherapies/targeted agents, and an intrinsic tumor radio-/chemo-resistance. Ataxia-telangiectasia mutated (ATM) protein orchestrates the cellular DNA damage response (DDR) to cytotoxic DNA double-strand breaks induced by ionizing radiation (IR). ATM genetic ablation or pharmacological inhibition results in tumor cell hypersensitivity to IR. We report the primary pharmacology of the clinical-grade, exquisitely potent (cell IC50, 0.78 nM), highly selective [>10,000-fold over kinases within the same phosphatidylinositol 3-kinase-related kinase (PIKK) family], orally bioavailable ATM inhibitor AZD1390 specifically optimized for BBB penetration confirmed in cynomolgus monkey brain positron emission tomography (PET) imaging of microdosed 11C-labeled AZD1390 (Kp,uu, 0.33). AZD1390 blocks ATM-dependent DDR pathway activity and combines with radiation to induce G2 cell cycle phase accumulation, micronuclei, and apoptosis. AZD1390 radiosensitizes glioma and lung cancer cell lines, with p53 mutant glioma cells generally being more radiosensitized than wild type. In in vivo syngeneic and patient-derived glioma as well as orthotopic lung-brain metastatic models, AZD1390 dosed in combination with daily fractions of IR (whole-brain or stereotactic radiotherapy) significantly induced tumor regressions and increased animal survival compared to IR treatment alone. We established a pharmacokinetic-pharmacodynamic-efficacy relationship by correlating free brain concentrations, tumor phospho-ATM/phospho-Rad50 inhibition, apoptotic biomarker (cleaved caspase-3) induction, tumor regression, and survival. On the basis of the data presented here, AZD1390 is now in early clinical development for use as a radiosensitizer in central nervous system malignancies.


Asunto(s)
Proteínas de la Ataxia Telangiectasia Mutada/antagonistas & inhibidores , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/mortalidad , Inhibidores de Proteínas Quinasas/farmacología , Fármacos Sensibilizantes a Radiaciones/farmacología , Animales , Apoptosis/efectos de los fármacos , Barrera Hematoencefálica/efectos de los fármacos , Barrera Hematoencefálica/metabolismo , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Permeabilidad de la Membrana Celular , Modelos Animales de Enfermedad , Evaluación Preclínica de Medicamentos , Humanos , Ratones , Fosforilación , Inhibidores de Proteínas Quinasas/química , Tolerancia a Radiación/efectos de los fármacos , Fármacos Sensibilizantes a Radiaciones/química , Transducción de Señal/efectos de los fármacos , Resultado del Tratamiento , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Rayos X , Ensayos Antitumor por Modelo de Xenoinjerto
18.
Basic Clin Pharmacol Toxicol ; 122(1): 165-175, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28815909

RESUMEN

Peripheral neuropathy is one of the most common complications of diabetic hyperglycaemia. Insulin-induced hypoglycaemia (IIH) might potentially exacerbate or contribute to neuropathy as hypoglycaemia also causes peripheral neuropathy. In rats, IIH induces neuropathy associated with skeletal muscle changes. Aims of this study were to investigate the progression and sequence of histopathologic changes caused by chronic IIH in rat peripheral nerves and skeletal muscle, and whether such changes were reversible. Chronic IIH was induced by infusion of human insulin, followed by an infusion-free recovery period in some of the animals. Sciatic, plantar nerves and thigh muscle were examined histopathologically after four or eight weeks of infusion and after the recovery period. IIH resulted in high incidence of axonal degeneration in sciatic nerves and low incidence in plantar nerves indicating proximo-distal progression of the neuropathy. The neuropathy progressed in severity (sciatic nerve) and incidence (sciatic and plantar nerve) with the duration of IIH. The myopathy consisted of groups of angular atrophic myofibres which resembled histopathologic changes classically seen after denervation of skeletal muscle, and severity of the myofibre atrophy correlated with severity of axonal degeneration in sciatic nerve. Both neuropathy and myopathy were still present after four weeks of recovery, although the neuropathy was less severe. In conclusion, the results suggest that peripheral neuropathy induced by IIH progresses proximo-distally, that severity and incidence increase with duration of the hypoglycaemia and that these changes are partially reversible within four weeks. Furthermore, IIH-induced myopathy is most likely secondary to the neuropathy.


Asunto(s)
Diabetes Mellitus/tratamiento farmacológico , Hipoglucemia/fisiopatología , Hipoglucemiantes/efectos adversos , Músculo Esquelético/patología , Enfermedades del Sistema Nervioso Periférico/fisiopatología , Animales , Atrofia/etiología , Enfermedad Crónica , Diabetes Mellitus/sangre , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Femenino , Miembro Posterior/inervación , Miembro Posterior/patología , Miembro Posterior/fisiopatología , Humanos , Hipoglucemia/sangre , Hipoglucemia/inducido químicamente , Insulina/efectos adversos , Masculino , Músculo Esquelético/inervación , Músculo Esquelético/fisiopatología , Enfermedades del Sistema Nervioso Periférico/sangre , Enfermedades del Sistema Nervioso Periférico/etiología , Ratas , Ratas Sprague-Dawley , Nervio Ciático/patología , Nervio Tibial/fisiopatología
19.
Int J Endocrinol ; 2017: 7861236, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28421113

RESUMEN

The brain is vulnerable to hypoglycaemia due to a continuous need of energy substrates to meet its high metabolic demands. Studies have shown that severe acute insulin-induced hypoglycaemia results in oxidative stress in the rat brain, when neuroglycopenia cannot be evaded despite increased levels of cerebral glucose transporters. Compensatory measures in the brain during chronic insulin-induced hypoglycaemia are less well understood. The present study investigated how the brain of nondiabetic rats copes with chronic insulin-induced hypoglycaemia for up to eight weeks. Brain level of different substrate transporters and redox homeostasis was evaluated. Hyperinsulinaemia for 8 weeks consistently lowered blood glucose levels by 30-50% (4-6 mM versus 7-9 mM in controls). The animals had increased food consumption, body weights, and hyperleptinaemia. During infusion, protein levels of the brain neuronal glucose transporter were decreased, whereas levels of lipid peroxidation products were unchanged. Discontinued infusion was followed by transient systemic hyperglycaemia and decreased food consumption and body weight. After 4 weeks, plasma levels of lipid peroxidation products were increased, possibly as a consequence of hyperglycaemia-induced oxidative stress. The present data suggests that chronic moderate hyperinsulinaemic hypoglycaemia causes increased body weight and hyperleptinaemia. This is accompanied by decreased neuronal glucose transporter levels, which may be leptin-induced.

20.
Basic Clin Pharmacol Toxicol ; 121(1): 53-66, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28218988

RESUMEN

New insulin analogues with a longer duration of action and a 'peakless' pharmacokinetic profile have been developed to improve efficacy, safety and convenience for patients with diabetes. During non-clinical development, according to regulatory guidelines, these analogues are tested in healthy euglycaemic rats rendering them persistently hypoglycaemic. Little is known about the effect of persistent (24 hr/day) insulin-induced hypoglycaemia (IIH) in rats, complicating interpretation of results in pre-clinical studies with new longer-acting insulin analogues. In this study, we investigated the effects of persistent IIH and their reversibility in euglycaemic rats. Histopathological changes in insulin-infused animals included partly reversible axonal and reversible myofibre degeneration in peripheral nerve and skeletal muscle tissue, respectively, as well as reversible pancreatic islet atrophy and partly reversible increase in unilocular adipocytes in brown adipose tissue. Additionally, results suggested increased gluconeogenesis. The observed hyperphagia, the pancreatic, peripheral nerve and skeletal muscle changes were considered related to the hypoglycaemia. Cessation of insulin infusion resulted in transient hyperglycaemia, decreased food consumption and body-weight loss before returning to control levels. The implications for the interpretation of non-clinical studies with long-acting insulin analogues are discussed.


Asunto(s)
Glucemia/efectos de los fármacos , Hiperglucemia/etiología , Hipoglucemia/inducido químicamente , Hipoglucemiantes/toxicidad , Insulina de Acción Prolongada/toxicidad , Animales , Axones/efectos de los fármacos , Axones/patología , Glucemia/análisis , Modelos Animales de Enfermedad , Femenino , Gluconeogénesis/efectos de los fármacos , Hiperglucemia/sangre , Hiperfagia/etiología , Hipoglucemia/sangre , Hipoglucemia/complicaciones , Masculino , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/patología , Nervios Periféricos/efectos de los fármacos , Nervios Periféricos/patología , Ratas , Ratas Sprague-Dawley , Factores de Tiempo , Pérdida de Peso/efectos de los fármacos
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