Humoral response after the fourth dose of the SARS-CoV-2 vaccine in the CKD spectrum: a prespecified analysis of the SENCOVAC study.

BACKGROUND: There is scarce evidence on the fourth dose of severe acute respiratory syndrome coronavirus 2 vaccines in chronic kidney disease (CKD) patients. We evaluated the humoral response and effectivity of the fourth dose in the CKD spectrum: non-dialysis CKD (ND-CKD), haemodialysis (HD), peritoneal dialysis (PD) and kidney transplant (KT) recipients. METHODS: This is a prespecified analysis of the prospective, observational, multicentric SENCOVAC study. In patients with CKD who had received a complete initial vaccination and one or two boosters and had anti-Spike antibody determinations 6 and 12 months after the initial vaccination, we analysed factors associated with persistent negative humoral response and higher anti-Spike antibody titres as well as the efficacy of vaccination on coronavirus disease 2019 (COVID-19) severity. RESULTS: Of 2186 patients (18% KT, 8% PD, 69% HD and 5% ND-CKD), 30% had received a fourth dose. The fourth dose increased anti-Spike antibody titres in HD (P = .001) and ND-CKD (P = .014) patients and seroconverted 72% of previously negative patients. Higher anti-Spike antibody titres at 12 months were independently associated with repeated exposure to antigen (fourth dose, previous breakthrough infections), previous anti-Spike antibody titres and not being a KT recipient. Breakthrough COVID-19 was registered in 137 (6%) patients, 5% of whom required admission. Admitted patients had prior titres <620 UI/ml and median values were lower (P = .020) than in non-admitted patients. CONCLUSIONS: A fourth vaccine dose increased anti-Spike antibody titres or seroconverted many CKD patients, but those with the highest need for a vaccine booster (i.e. those with lower pre-booster antibody titres or KT recipients) derived the least benefit in terms of antibody titres. Admission for breakthrough COVID-19 was associated with low anti-Spike antibody titres.

HEMATOLOGIC AND BIOCHEMICAL VALUES OF FREE-RANGING HAWKSBILL SEA TURTLES (ERETMOCHELYS IMBRICATA) IN GLOVER'S REEF, BELIZE.

Blood samples were obtained from the dorsal cervical sinus of free-ranging hawksbill sea turtles (Eretmochelys imbricata) collected at Glover's Reef Marine Reserve, 42 km east of the coast of Belize, for hematology and plasma biochemistry analysis. Unknown sex, subadult turtles (N = 32) were sampled in 2013 (n = 22) and 2017 (n = 10). To provide a more robust data set, parameters that did not have statistically significant differences were pooled and treated as a single population. Eleven hematologic parameters were evaluated; of these, five were pooled. Twenty-three plasma biochemical parameters were evaluated; of these, 15 were pooled. The PCV observed in this study (mean 33.44%) was double that observed in two studies of juvenile hawksbills in Dubai (means 17% and 16%), whereas the total WBC count was half that observed in immature and adult hawksbills sampled in the Galápagos (mean 2.91 × 103 versus 5.3 × 103/µl). Total protein and albumin were lower than regionally similar, adult female hawksbills in Brazil (means 3.36 versus 5.45 g/dl and 0.93 versus 2.11 g/dl, respectively). Globulins were higher (mean 2.43 versus 1.06 and 0.5 g/dl), driving the albumin:globulin ratio lower than that observed in two studies of juvenile hawksbills in Dubai (0.4:1 versus 1.1:1 and 1:1, respectively). These findings represent a geographically distinct population from previous reports, highlight the variability in blood parameters from disparate populations, and reaffirm the vital importance of considering a multitude of variables when interpreting reptilian blood values. The similarities in the majority of values observed in 2013 and 2017 provide confidence in the stability of these parameters in this population.

COVID-19 in lung transplant recipients: A multicenter study.

This study describes the clinical presentation, treatment, and outcomes of SARS-CoV-2 infection in lung transplant recipients (LTRs). This is a multicenter, retrospective study of all adult LTRs with confirmed SARS-CoV-2 infection from March 4 until April 28, 2020 in six Spanish reference hospitals for lung transplantation. Clinical and radiological data, treatment characteristics, and outcomes were reviewed. Forty-four cases were identified in that period. The median time from transplantation was 4.2 (interquartile range: 1.11-7.3) years. Chest radiography showed acute parenchymal abnormalities in 32 (73%) cases. Hydroxychloroquine was prescribed in 41 (93%), lopinavir/ritonavir (LPV/r) in 14 (32%), and tocilizumab in 19 (43%) patients. There was a strong interaction between tacrolimus and LPV/r in all cases. Thirty-seven (84%) patients required some degree of respiratory support and/or oxygen therapy, and 13 (30%) were admitted to intermediate or intensive critical care units. Seventeen (39%) patients had died and 20 (45%) had been discharged at the time of the last follow-up. Deceased patients had a worse respiratory status and chest X-ray on admission and presented with higher D-dimer, interleukin-6, and lactate dehydrogenase levels. In this multicenter LTR cohort, SARS-CoV-2 presented with high mortality. Additionally, the severity of disease on presentation predicted subsequent mortality.

Magnesium Exchanged Zirconium Metal-Organic Frameworks with Improved Detoxification Properties of Nerve Agents.

UiO-66, MOF-808 and NU-1000 metal-organic frameworks exhibit a differentiated reactivity toward [Mg(OMe)2(MeOH)2]4 related to their pore accessibility. Microporous UiO-66 remains unchanged while mesoporous MOF-808 and hierarchical micro/mesoporous NU-1000 materials yield doped systems containing exposed MgZr5O2(OH)6 clusters in the mesoporous cavities. This modification is responsible for a remarkable enhancement of the catalytic activity toward the hydrolytic degradation of P-F and P-S bonds of toxic nerve agents, at room temperature, in unbuffered aqueous solutions.

High-fat diet abolishes the cardioprotective effects of ischemic postconditioning in murine models despite increased thioredoxin-1 levels.

Ischemic postconditioning (PostC) reduces infarct size in healthy experimental models. However, if protective effects of PostC are abolished during early stages of atherosclerotic and if this is related with a disbalance in mitochondrial energetics and alterations in thioredoxin-1 (Trx1) is still unknown. The objectives were to generate a murine high-fat diet (HFD)-fed model that developed in a phenotype consistent with early stages of atherosclerosis to then evaluate whether HFD exposure increased oxidative stress and consequently abolished the cardioprotection conferred by PostC. We used C57/BL6 mice fed with control diet (CD) or HFD for 12 weeks. Isolated mice hearts were subjected to 30 min of ischemia and 120 min of reperfusion (I/R group). For PostC group, after ischemia, six cycles of reperfusion/ischemia were performed (10 s per cycle) at the onset of reperfusion. In CD group, the PostC reduced infarct size (CD-I/R: 52.14 ± 2.8 vs. CD-PostC: 36.58 ± 1.8, P < 0.05) and increased phosphorylation of GSK3ß (CD-PostC: 2.341 ± 1.03 vs. CD-Baseline: 0.923 ± 0.41 AUOD, P < 0.05), and this cardioprotection was abolished in HFD-exposed mice. HFD increased hydrogen peroxide levels, produced a shift towards an oxidized intracellular environment (GSSG/GSH2), and increased Trx1 expression with higher fractions of oxidized protein. State 3 mitochondrial oxygen consumption in basal conditions decreased 24% in HFD-exposed mice and PostC improved state 3 values only in CD mice. Cellular redox state and mitochondrial bioenergetics were altered in HFD-exposed mice. We demonstrated that alterations in redox state at early stages of atherosclerosis abolished cardioprotective mechanisms, such as those induced by PostC, even with increased Trx1 levels.

Dyslipidemia in Ischemia/Reperfusion Injury.

Ischemic heart disease is the main cause of morbidity and mortality in the developed world. Although reperfusion therapies are currently the best treatment for this entity, the restoration of blood flow leads, under certain circumstances, to a form of myocardial damage called reperfusion injury. Several studies have shown that age, sex, smoking, diabetes and dyslipidemia are risk factors for cardiovascular diseases. Among these risk factors, dyslipidemias are present in 40% of patients with ischemic heart disease and represent the clinical factor with the greatest impact on the prognosis of patients with cardiovascular diseases. It is known that during reperfusion the increase of the oxidative stress is perhaps one of the most important mechanisms implicated in cell damage. That is why several researchers have studied protective mechanisms against reperfusion injury, such as the ischemic pre- and post- conditioning, making emphasis mainly on the reduction of oxidative stress. However, few of these efforts have been successfully translated into the clinical setting. The controversial results in regards to the relation between cardioprotective mechanisms and dyslipidemia/hypercholesterolemia are mainly due to the difference among quality, composition and the time of administration of hypercholesterolemic diets, as well as the difference in the species used in each of the studies. Therefore, in order to compare results, it is crucial that all variables that could modify the obtained results are taken into consideration.

Myocardial triggers involved in activation of remote ischaemic preconditioning.

NEW FINDINGS: What is the central question of this study? Ischaemia-reperfusion of peripheral tissues protects the heart from subsequent myocardial ischaemia-reperfusion injury, a phenomenon referred to as remote ischaemic preconditioning (rIPC). This study evaluated the possible myocardial triggers of rIPC. What is the main finding and its importance? Remote ischaemic preconditioning reduces infarct size through a vagal pathway and a mechanism involving phosphorylation of Akt and endothelial nitric oxide synthase, opening of mitochondrial ATP-dependent K(+) channels and an increase in mitochondrial H2 O2 production. All these phenomena occur before the myocardial ischaemia; hence, they could act as 'triggers' of rIPC. It has been proposed that remote ischaemic preconditioning (rIPC) activates a parasympathetic neural pathway. However, the myocardial intracellular mechanism of rIPC remains unclear. Here, we characterized some of the intracellular signals participating as rIPC triggers. Isolated rat hearts were subjected to 30 min of global ischaemia and 120 min of reperfusion (Non-rIPC group). In a second group, before the isolation of the heart, an rIPC protocol (three cycles of hindlimb ischaemia-reperfusion) was performed. The infarct size was measured with tetrazolium staining. Expression/phosphorylation of Akt and endothelial nitric oxide synthase (eNOS) and mitochondrial H2 O2 production were evaluated at the end of the rIPC protocol, before myocardial ischaemia-reperfusion. The rIPC significantly decreased the infarct size and induced Akt and eNOS phosphorylation. The protective effect on infarct size was abolished by cervical vagal section, l-NAME (an NO synthesis inhibitor) and 5-hydroxydecanoate (a mitochondrial ATP-dependent K(+) channel blocker). Mitochondrial production of H2 O2 was increased by rIPC, whereas it was abolished by cervical vagal section, l-NAME and 5-hydroxydecanoate. We conclude that rIPC activates a parasympathetic vagal pathway and a mechanism involving the phosphorylation of Akt and eNOS, the opening of mitochondrial ATP-dependent K(+) channels and the release of H2 O2 by the mitochondria. All these phenomena occur before myocardial ischaemia and could act as triggers of rIPC.

Ischemic postconditioning confers cardioprotection and prevents reduction of Trx-1 in young mice, but not in middle-aged and old mice.

Thioredoxin-1 (Trx-1) is part of an antioxidant system that maintains the cell redox homeostasis but their role on ischemic postconditioning (PostC) is unknown. The aim of this work was to determine whether Trx-1 participates in the cardioprotective mechanism of PostC in young, middle-aged, and old mice. Male FVB young (Y: 3 month-old), middle-aged (MA: 12 month-old), and old (O: 20 month-old) mice were used. Langendorff-perfused hearts were subjected to 30 min of ischemia and 120 min of reperfusion (I/R group). After ischemia, we performed 6 cycles of R/I (10 s each) followed by 120 min of reperfusion (PostC group). We measured the infarct size (triphenyltetrazolium); Trx-1, total and phosphorylated Akt, and GSK3ß expression (Western blot); and the GSH/GSSG ratio (HPLC). PostC reduced the infarct size in young mice (I/R-Y: 52.3 ± 2.4 vs. PostC-Y: 40.0 ± 1.9, p < 0.05), but this protection was abolished in the middle-aged and old mice groups. Trx-1 expression decreased after I/R, and the PostC prevented the protein degradation in young animals (I/R-Y: 1.05 ± 0.1 vs. PostC-Y: 0.52 ± .0.07, p < 0.05). These changes were accompanied by an improvement in the GSH/GSSG ratio (I/R-Y: 1.25 ± 0.30 vs. PostC-Y: 7.10 ± 2.10, p < 0.05). However, no changes were observed in the middle-aged and old groups. Cytosolic Akt and GSK3ß phosphorylation increased in the PostC compared with the I/R group only in young animals. Our results suggest that PostC prevents Trx-1 degradation, decreasing oxidative stress and allowing the activation of Akt and GSK3ß to exert its cardioprotective effect. This protection mechanism is not activated in middle-aged and old animals.

Role of thioredoxin-1 in ischemic preconditioning, postconditioning and aged ischemic hearts.

Thioredoxin is one of the most important cellular antioxidant systems known to date, and is responsible of maintaining the reduced state of the intracellular space. Trx-1 is a small cytosolic protein whose transcription is induced by stress. Therefore it is possible that this antioxidant plays a protective role against the oxidative stress caused by an increase of reactive oxygen species concentration, as occurs during the reperfusion after an ischemic episode. However, in addition to its antioxidant properties, it is able to activate other cytoplasmic and nuclear mediators that confer cardioprotection. It is remarkable that Trx-1 also participates in myocardial protection mechanisms such as ischemic preconditioning and postconditioning, activating proteins related to cellular survival. In this sense, it has been shown that Trx-1 inhibition abolished the preconditioning cardioprotective effect, evidenced through apoptosis and infarct size. Furthermore, ischemic postconditioning preserves Trx-1 content at reperfusion, after ischemia. However, comorbidities such as aging can modify this powerful cellular defense leading to decrease cardioprotection. Even ischemic preconditioning and postconditioning protocols performed in aged animal models failed to decrease infarct size. Therefore, the lack of success of antioxidants therapies to treat ischemic heart disease could be solved, at least in part, avoiding the damage of Trx system.

Changes in the loading conditions induced by vagal stimulation modify the myocardial infarct size through sympathetic-parasympathetic interactions.

In a previous research, we described that vagal stimulation increases the infarct size by sympathetic co-activation. The aim of this study was to determine if hemodynamic changes secondary to the vagal stimulation are able to activate sympathetic compensatory neural reflexes, responsible for increasing the infarct size. A second goal was to determine if intermittent vagal stimulation avoids sympathetic activation and reduces infarct size by muscarinic activation of the Akt/glycogen synthase kinase 3 ß (GSK-3ß) pathway. Rabbits were subjected to 30 min of regional myocardial ischemia and 3 h of reperfusion without vagal stimulation, or the following protocols of right vagus nerve stimulation for 10 min before ischemia: (a) continuous vagal stimulation and (b) intermittent vagal stimulation (cycles of 10 s ON/50 s OFF). Continuous vagal stimulation increased the infarct size (70.7 ± 4.3 %), even after right vagal section (68.6 ± 4.1 %) compared with control group (52.0 ± 3.7 %, p < 0.05). Bilateral vagotomy, pacing, and esmolol abolished the deleterious effect, reaching an infarct size of 43.3 ± 5.1, 43.5 ± 2.1, and 46.0 ± 4.6 % (p < 0.05), respectively. Intermittent stimulation reduced the infarct size to 29.8 ± 3.0 % (p < 0.05 vs I/R). This effect was blocked with atropine (50.2 ± 3.6 %, p < 0.05). Continuous vagal stimulation induced bradycardia and increased the loading conditions and wall stretching of the atria. These changes provoked the co-activation reflex of the sympathetic nervous system, observed by the rise in plasmatic catecholamine levels, which increased the infarct size. Sympathetic co-activation was abolished by continuous vagal stimulation with constant heart rate or parasympathetic deafferentation. Intermittent vagal stimulation attenuated the sympathetic tone and reduced the infarct size by the muscarinic activation of the Akt pathway and GSK-3ß inhibition. Continuous stimulation only phosphorylated Akt and GSK-3ß when esmolol was administered.

Selective TNF-α targeting with infliximab attenuates impaired oxygen metabolism and contractile function induced by an acute exposure to air particulate matter.

Inflammation plays a central role in the onset and progression of cardiovascular diseases associated with the exposure to air pollution particulate matter (PM). The aim of this work was to analyze the cardioprotective effect of selective TNF-α targeting with a blocking anti-TNF-α antibody (infliximab) in an in vivo mice model of acute exposure to residual oil fly ash (ROFA). Female Swiss mice received an intraperitoneal injection of infliximab (10 mg/kg body wt) or saline solution, and were intranasally instilled with a ROFA suspension (1 mg/kg body wt). Control animals were instilled with saline solution and handled in parallel. After 3 h, heart O2 consumption was assessed by high-resolution respirometry in left ventricle tissue cubes and isolated mitochondria, and ventricular contractile reserve and lusitropic reserve were evaluated according to the Langendorff technique. ROFA instillation induced a significant decrease in tissue O2 consumption and active mitochondrial respiration by 32 and 31%, respectively, compared with the control group. While ventricular contractile state and isovolumic relaxation were not altered in ROFA-exposed mice, impaired contractile reserve and lusitropic reserve were observed in this group. Infliximab pretreatment significantly attenuated the decrease in heart O2 consumption and prevented the decrease in ventricular contractile and lusitropic reserve in ROFA-exposed mice. Moreover, infliximab-pretreated ROFA-exposed mice showed conserved left ventricular developed pressure and cardiac O2 consumption in response to a ß-adrenergic stimulus with isoproterenol. These results provides direct evidence linking systemic inflammation and altered cardiac function following an acute exposure to PM and contribute to the understanding of PM-associated cardiovascular morbidity and mortality.

Dystrophin proteolysis: a potential target for MMP-2 and its prevention by ischemic preconditioning.

Dystrophin is responsible for the mechanical stabilization of the sarcolemma, and it has been shown that it is one of the most sensitive proteins to ischemic injury. However, the enzyme responsible for this proteolysis is still unknown. Isolated rabbit hearts were subjected to 30 min of global ischemia with and without reperfusion (180 min) to determine whether dystrophin is cleaved by matrix metalloproteinase (MMP)-2 during acute ischemia and whether ischemic preconditioning (PC) prevents dystrophin breakdown through MMP-2 inhibition. The activity of MMP-2 was evaluated by zymography and using doxycycline as an inhibitor. Also, to stimulate MMP-2 activity without ischemia, SIN-1 was administered in the absence and presence of doxycycline. Finally, we considered the PC effect on MMP-2 activity and dystrophin expression. The dystrophin level decreased during ischemia, reaching 21% of control values (P < 0.05), but the spectrin level remained unchanged. MMP-2 activity increased 71% during ischemia compared with control values (P < 0.05). Doxycycline administration before ischemia prevented dystrophin breakdown. In normoxic hearts, SIN-1 increased thiobarbituric acid-reactive substances by 33% (P < 0.05) and MMP-2 activity by 36% (P < 0.05) and significantly reduced the dystrophin level to 23% of control values (P < 0.05). PC significantly prevented dystrophin breakdown by inhibiting MMP-2 activity, and the dystrophin level reached 89% of control values (P < 0.05). In conclusion, MMP-2 could be responsible for the proteolysis of dystrophin. Thus, dystrophin emerges as a possible novel substrate for MMP-2 in the context of ischemic injury. Furthermore, our results demonstrate that ischemic PC prevents dystrophin breakdown most likely by inhibiting MMP-2 activity.

Ischemic postconditioning reduces infarct size through the α1-adrenergic receptor pathway.

The α1-adrenergic receptors (α1-ARs) are involved in preconditioning. Given that certain intracellular pathways seem to be shared by preconditioning and postconditioning, it is possible that postconditioning could also be mediated by α1-ARs. The objective was to evaluate, by analyzing infarct size, if α1-ARs activation could trigger postconditioning and also determine Akt and glycogen synthase kinase 3ß (GSK-3ß) phosphorylation. Langendorff-perfused rat hearts were subjected to 30 minutes of ischemia and 120 minutes of reperfusion (I/R; n = 8). After 30 minutes of global ischemia, we performed 6 cycles of reperfusion/ischemia of 10 seconds each, followed by 120 minutes of reperfusion [ischemic postconditioning group (postcon); n = 9]. In another postcon group, we administered prazosin during postcon protocol (postcon + prazosin; n = 7). Finally, we repeated the I/R group, but prazosin (prazosin; n = 7), phenylephrine (PE; n = 5) and clonidine (CL; n = 6) were administered during the first 2 minutes of reperfusion. Infarct size was measured using the triphenyltetrazolium chloride technique. Total and phosphorylated Akt and mitochondrial GSK-3ß expression were measured by Western blot. Infarct size was 58.1 ± 5.1% in I/R. Postcon and PE reduced infarct size to 40.1 ± 2.9% and 35.3 ± 5.5%, respectively (P < 0.05 vs. I/R). Postcon + prazosin administration abolished the beneficial effect on infarct size (61.6 ± 4.5%; P < 0.05 vs. postcon). Cytosolic Akt phosphorylation and mitochondrial GSK-3ß phosphorylation were higher in the postcon and PE groups compared with the I/R and postcon + prazosin groups. Prazosin or clonidine administration did not modify neither protein expression nor infarct size. Our data demonstrate that postconditioning decrease infarct size by activation of the α1-AR pathway through Akt and GSK-3ß phosphorylation.

Enhancing motor functional recovery in spinal cord injury through pharmacological inhibition of Dickkopf-1 with BHQ880 antibody.

BACKGROUND: Mounting experimental evidence has underscored the remarkable role played by the Wnt family of proteins in the spinal cord functioning and therapeutic potential in spinal cord injury (SCI). We aim to provide a therapeutic prospect associated with the modulation of canonical Wnt signaling, examining the spatio-temporal expression pattern of Dickkopf-1 (Dkk1) and its neutralization after SCI. We employ an intraparenchymal injection of the clinically validated Dkk1-blocking antibody, BHQ880, to elucidate its effects in SCI. METHODS: A rat model of contusion SCI was used. Histological analyses were performed, wherein Dkk1 protein was sought, and ELISA analyses were employed for Dkk1 detection in cerebrospinal fluid and serum. To ascertain the BHQ880 therapeutic effect, rats were subjected to SCI and then injected with the antibody in the lesion epicenter 24 hours post-injury (hpi). Subsequent evaluation of motor functional recovery extended up to 56 days post-injury (dpi). qRT-PCR and histological analyses were conducted. RESULTS: We demonstrate the presence of Dkk1 in the healthy rat spinal cord, with pronounced alterations observed following injury, primarily concentrated in the epicenter regions. Notably, a significative upregulation of Dkk1 was detected at 24 hpi, peaking at 3 dpi and remaining elevated until 42 dpi. Moreover, we revealed that early administration of BHQ880 considerably improved motor functional recovery, promoted preservation of myelinated tissue, and reduced astroglial and microglia/macrophage reactivity. Furthermore, there was a decrease in the acute expression of different inflammatory genes. CONCLUSIONS: Collectively, our findings highlight the therapeutic potential of BHQ880 treatment in the context of SCI.

Role of the parasympathetic nervous system in cardioprotection by remote hindlimb ischaemic preconditioning.

This investigation was designed to determine the participation of the vagus nerve and muscarinic receptors in the remote ischaemic preconditioning (rIPC) mechanism. New Zealand rabbits were anaesthetized, and the femoral artery was dissected. After 30 min of monitoring, the hearts were isolated and subjected to 30 min of global no-flow ischaemia and 180 min of reperfusion (non-rIPC group). The ventricular function was evaluated, considering the left ventricular developed pressure and the left ventricular end-diastolic pressure. In the rIPC group, the rabbits were subjected to three cycles of hindlimb ischaemia (5 min) and reperfusion (5 min), and the same protocol as that used in non-rIPC group was then repeated. In order to evaluate the afferent neural pathway during the rIPC protocol we used two groups, one in which the femoral and sciatic nerves were sectioned and the other in which the spinal cord was sectioned (T9-T10 level). To study the efferent neural pathway during the rIPC protocol, the vagus nerve was sectioned and, in another group, atropine was administered. The effect of vagal stimulation was also evaluated. An infarct size of 40.8 ± 3.1% was obtained in the non-rIPC group, whereas in rIPC group the infarct size decreased to 16.4 ± 3.5% (P < 0.05). During the preconditioning protocol, the vagus nerve section and the atropine administration each abolished the effect of rIPC on infarct size. Vagal stimulation mimicked the effect of rIPC, decreasing infarct size to 15.2 ± 4.7% (P < 0.05). Decreases in infarct size were accompanied by improved left ventricular function. We demonstrated the presence of a neural afferent pathway, because the spinal cord section completely abolished the effect of rIPC on infarct size. In conclusion, rIPC activates a neural afferent pathway, the cardioprotective signal reaches the heart through the vagus nerve (efferent pathway), and acetylcholine activates the ischaemic preconditioning phenomenon when acting on the muscarinic receptors.

[Factors that predict depression in medical students]. / Factores que predicen depresión en estudiantes de medicina.

INTRODUCTION: High prevalence of depression and anxiety symptoms has been observed in medical students. OBJECTIVE: To identify predictors of depressive symptoms according to CES-D in students during their first year of medical education. METHODS: We evaluated 517 students in their first year of medical education with the following instruments: Centers for Epidemiology Studies for Depression Scale, State-Trait anxiety inventory, and stressors list. A linear regression analysis was carried out to evaluate variables predicting high CES-D scores. RESULTS: We observed that anxiety and depressive symptoms were more frequent in women, as well as stressors. Predictors of depression were state of anxiety, stressors, and low socioeconomic level. CONCLUSIONS: It is important to implement support measures for students who live with stress factors, suffering anxiety, or with a low socioeconomic level.

Key Factors in Crane-Related Occupational Accidents in the Spanish Construction Industry (2012-2021).

The construction industry is one of the riskiest sectors worldwide, with crane operations being one of the most dangerous activities. The aim of this study was to gain insight into the key factors involved in crane-related occupational accidents in the construction industry in Spain. To this end, 1314 accidents involving cranes were analyzed from a total of 241,937 accidents that occurred in the construction of buildings. The data were collected from the Spanish government's occupational accident statistics corresponding to the years 2012-2021. The results evidenced a statistically significant relationship between cranes as the material agent and the size of the company, with 95% of cases corresponding to small- or medium-sized companies (less than 250 employees). Additionally, it shows how the crane operator is identified as a material contributor to crane accidents in the construction industry, and may be considered a key component to these accidents. In conclusion, improving the knowledge gained about the key factors in crane-related accidents at work in the construction industry provides essential information that helps to design and implement appropriate preventive measures to avoid the recurrence of unwanted events with these machines.

Belize Blue Carbon: Establishing a national carbon stock estimate for mangrove ecosystems.

Mangrove ecosystems are among the most economically and ecologically valuable marine environments in the world. Mangroves are effective at long-term carbon storage within their sediments and are estimated to hold 12 billion metric tons of carbon worldwide. These ecosystems are therefore vitally important for carbon sequestration and, by extension, climate change mitigation. As part of the Paris Agreement, participating countries agree to provide plans to reduce their carbon emissions, or nationally determined contributions (NDCs). However, despite mangroves being recognized as important nature-based solutions, many countries still lack national data on carbon stocks and must use global or regional averages, which may not be sufficiently accurate. Here, we present the national carbon stock estimate of mangrove ecosystems for the NDC of Belize, acquired through a collaborative approach involving government agencies and NGOs. We conducted a comprehensive sampling of mangroves across the country, including a range of mangrove ecotypes. The mean total ecosystem carbon stock (TECS) for the nation was 444.1 ± 21.0 Mg C ha-1, with 74.4 ± 6.2 Mg C ha-1 in biomass stocks, and 369.7 ± 17.7 Mg C ha-1 in sediment stocks. Combining these data with a recent mapping effort, we provide the first national comprehensive mangrove carbon stock estimate of 25.7 Tg C. The national mean from this study varies from previous global analyses, which can under- or overestimate TECS by as much as 0.6 Tg C and 16.5 Tg C, respectively, depending on the study. These data supported the NDC update of Belize, and can be used to inform the country's mangrove protection and restoration commitments. The collaborative approach of this work should serve as a blueprint for other countries seeking to conserve natural blue carbon sinks as a strategy to achieve their climate targets.

High cholesterol diet effects on ischemia-reperfusion injury of the heart.

Ischemic heart disease is the leading cause of morbi-mortality in developed countries. Both ischemia-reperfusion injury and mechanisms of cardioprotection have been studied for more than 50 years. It is known that the physiopathological mechanism of myocardial ischemia involves several factors that are closely related to its development, of which hypercholesterolemia is one of the main ones. Therefore, the objective of this review was to elucidate the effects of a high-cholesterol diet on normal ventricular function and ischemia-reperfusion injury associated phenomenon such as post-ischemic ventricular dysfunction (stunned myocardium). Although there exist many studies considering several aspects of this physiopathological entity, the majority were carried out on normal animals. Thus, experiments carried out on hypercholesterolemic models are controversial, in particular those evaluating different mechanisms of cardioprotection such as ischemic preconditioning and postconditioning, and cardioprotection granted by drugs such as statins, which apart from exerting a lipid-lowering effect, exert pleiotropic effects providing cardioprotection against ischemia-reperfusion injury. These controversial results concerning the mechanisms of cardioprotection vary according to quality, composition, and time of administration of the high-cholesterol diet, as well as the species used in each experiment. Thus, to compare the results it is necessary to take all of these variables into account, since they can change the obtained results.