Anatomical Vascular Differences and Leishmania-Induced Vascular Morphological Changes Are Associated with a High Parasite Load in the Skin of Dogs Infected with Leishmania infantum.

Canine visceral leishmaniasis (CVL), caused by the protozoan Leishmania infantum, affects several organs, including the skin. Dogs are considered the major domestic reservoir animals for leishmaniasis, and through their highly parasitized skin, they can serve as a source of infection for sandfly vectors. Therefore, studies of the skin parasite-host relationship can contribute to the understanding of the infectious dissemination processes of parasites in the dermis and help to identify targets for diagnosis and treatment. Thus, the aim of this study was to evaluate the association of anatomical vascular differences and Leishmania-induced vascular morphological changes with clinical signs and parasite load by analyzing the ear and abdominal skin from dogs naturally infected with L. infantum. Paired samples of ear and abdominal skin from L. infantum-positive dogs (n = 26) were submitted for histological and immunohistochemistry analyses. The ear skin samples showed a more intense and more diffusely distributed granulomatous inflammatory reaction, a higher number and larger diameter of blood vessels, increased parasite load, higher expression of VEGF+ (vascular endothelial growth factor) and MAC 387+ (calprotectin) recently infiltrating cells, and more intense collagen disruption compared to the abdominal skin samples. Intracellular amastigotes were observed in blood vessels and inside endothelial cells and were diffusely distributed throughout the dermis in the ear skin samples. The NOS2/MAC387+ cell ratio was lower in the ear skin samples than in those of the abdomen, suggesting that in the ear dermis, the inflammatory infiltrate was less capable of producing NO and thereby control the parasite load. Together, these findings indicate how parasites and immune cells are distributed in the skin and suggest an important role for dermal vascularization in cellular influx and thereby in parasite dissemination through the skin of naturally infected dogs.

A comparative study on the quality of in vivo labeled red blood cell radionuclide ventriculography images employing different freeze-dried reagents.

Radionuclide ventriculography or Multi Gated Acquisition (MUGA) employing [ 99m Tc]Technetium red blood cell (RBC) labeling is considered the gold standard for cardiotoxicity assessments in cancer patients undergoing chemotherapy. This in-vivo RBC labeling technique involves the reduction of [ 99m Tc]Technetium by the stannous chloride present in freeze-dried reagent kits, with the pyrophosphate kit (PYP) being the most employed for this purpose. The literature, however, describes diethylenetriaminepentaacetic acid (DTPA) as an alternative to PYP, although a lack of comparative data from MUGA images between both reagents is noted. A retrospective cross-sectional observational study was conducted at the Brazilian National Cancer Institute Nuclear Medicine Service concerning 80 randomized MUGA images, 20 obtained employing DTPA between 2020 and 2023 and 60 obtained employing PYP between 2017 and 2020, applying the mean count per pixel (ct/pixel) and heart background (C/F) ratios as quality image indicators. Although the heart ct/pixel ratio was statistically lower in the DTPA images compared with PYP ( P  = 0.02), the C/F ratio was statistically similar when comparing both radiopharmaceuticals ( P  = 0.697). A semi-quantitative analysis of MUGA images obtained with DTPA and PYP indicates similar image quality, supporting the use of DTPA as an alternative to PYP without compromising diagnostic interpretations.

Artificial intelligence applied to analyzes during the pandemic: COVID-19 beds occupancy in the state of Rio Grande do Norte, Brazil.

The COVID-19 pandemic is already considered one of the biggest global health crises. In Rio Grande do Norte, a Brazilian state, the RegulaRN platform was the health information system used to regulate beds for patients with COVID-19. This article explored machine learning and deep learning techniques with RegulaRN data in order to identify the best models and parameters to predict the outcome of a hospitalized patient. A total of 25,366 bed regulations for COVID-19 patients were analyzed. The data analyzed comes from the RegulaRN Platform database from April 2020 to August 2022. From these data, the nine most pertinent characteristics were selected from the twenty available, and blank or inconclusive data were excluded. This was followed by the following steps: data pre-processing, database balancing, training, and test. The results showed better performance in terms of accuracy (84.01%), precision (79.57%), and F1-score (81.00%) for the Multilayer Perceptron model with Stochastic Gradient Descent optimizer. The best results for recall (84.67%), specificity (84.67%), and ROC-AUC (91.6%) were achieved by Root Mean Squared Propagation. This study compared different computational methods of machine and deep learning whose objective was to classify bed regulation data for patients with COVID-19 from the RegulaRN Platform. The results have made it possible to identify the best model to help health professionals during the process of regulating beds for patients with COVID-19. The scientific findings of this article demonstrate that the computational methods used applied through a digital health solution, can assist in the decision-making of medical regulators and government institutions in situations of public health crisis.

Half dose ChAdOx1 nCoV-19 vaccine was equivalent to full doses to reduce moderate and severe COVID-19 cases.

Objectives: Previously, we presented the effectiveness of ChAdOx1 nCoV-19 half-dose (HD) immunization for preventing new COVID-19 cases. Here, we evaluated the administration of an HD of ChAdOx1 nCoV-19 in the primary immunization protocol (up to two doses) in reducing moderate and severe cases, hospitalizations, and deaths when compared to the administration of full doses (FD) after a long-term follow-up. Methods: We evaluated data from 29,469 participants between January 2021 and November 2022 who received an HD or FD vaccine and crossed this information with their medical records to identify those who developed moderate or severe cases. All participants were classified into four groups according to their immunization status and followed 500 days after the last vaccine administration. Results: The propensity-score matching analysis indicates that the administration of the two HDs of ChAdOx1 nCoV-19 was equivalent to the use of two FDs to reduce moderate and severe COVID-19 cases. The relative risk of being infected and developing moderate or severe conditions after the administration of at least one HD or FD was similar 150 or 500 days after the administration of the immunizers. Conclusion: Administering two HDs can be used safely as a cost-effective alternative to the primary immunization protocol.

Digital health solution for monitoring and surveillance of Amyotrophic Lateral Sclerosis in Brazil.

Amyotrophic Lateral Sclerosis (ALS) is a complex and rare neurodegenerative disease given its heterogeneity. Despite being known for many years, few countries have accurate information about the characteristics of people diagnosed with ALS, such as data regarding diagnosis and clinical features of the disease. In Brazil, the lack of information about ALS limits data for the research progress and public policy development that benefits people affected by this health condition. In this context, this article aims to show a digital health solution development and application for research, intervention, and strengthening of the response to ALS in the Brazilian Health System. The proposed solution is composed of two platforms: the Brazilian National ALS Registry, responsible for the data collection in a structured way from ALS patients all over Brazil; and the Brazilian National ALS Observatory, responsible for processing the data collected in the National Registry and for providing a monitoring room with indicators on people diagnosed with ALS in Brazil. The development of this solution was supported by the Brazilian Ministry of Health (MoH) and was carried out by a multidisciplinary team with expertise in ALS. This solution represents a tool with great potential for strengthening public policies and stands out for being the only public database on the disease, besides containing innovations that allow data collection by health professionals and/or patients. By using both platforms, it is believed that it will be possible to understand the demographic and epidemiological data of ALS in Brazil, since the data will be able to be analyzed by care teams and also by public health managers, both in the individual and collective monitoring of people living with ALS in Brazil.

Occurrence of serological reactions for Leptospira spp. in donkeys and mules from Minas Gerais, Brazil.

Research concerning leptospirosis in donkeys and mules has been neglected around the world. Therefore, the aim of this study was to investigate the epidemiological situation of the prevalence of anti-Leptospira spp. antibodies in donkeys and mules from the state of Minas Gerais, Brazil. Blood serum samples were collected from 180 animals (109 donkeys and 71 mules) in two rural properties from the state of Minas Gerais, Brazil, and then submitted to a microscopic agglutination test (MAT). Urea and creatinine values were also quantified. Epidemiological variables such as age, breeding system, contact with other animal species, source of water and food, vaccination against leptospirosis, presence of reproductive alterations, and rodent control were also investigated. From 180 samples collected, 39 (21.67%) showed positive results in the MAT, at a dilution ≥ 1:100. Some animals were reactive for more than one serovar. The serovar Tarassovi was the most frequent (14.07%), followed by Hardjo (11.85%) and Wolffi (11.11%). There was a statistically significant difference between animals from 0 to 3 years of age reactive in the MAT in comparison to the other age groups. Most of the animals had urea and creatinine concentrations within the acceptable reference limit; however, there was a significant increase in creatinine levels in some of the test animals. The studied properties showed differences in some epidemiological aspects such as vaccination of the animals, presence of reproductive problems in the herd, and rodent control. Such aspects pointed as risk factors that may influence the frequency of positive serological results in property 1. The present study demonstrated that the prevalence of leptospirosis in donkeys and mules is high and several serovars are being maintained by these animals, representing a potential public health risk.

Primary infection of BALB/c mice with a dengue virus type 4 strain leads to kidney injury.

BACKGROUND: Dengue is a disease caused by dengue virus (DENV-1 through -4). Among the four serotypes, DENV-4 remains the least studied. Acute kidney injury is a potential complication of dengue generally associated with severe dengue infection. OBJECTIVES: The goal of this study was to investigate the alterations caused by experimental dengue infection in the kidney of adult BALB/c mice. METHODS: In this study, BALB/c mice were infected through the intravenous route with a DENV-4 strain, isolated from a human patient. The kidneys of the mice were procured and subject to histopathological and ultrastructural analysis. FINDINGS: The presence of the viral antigen was confirmed through immunohistochemistry. Analysis of tissue sections revealed the presence of inflammatory cell infiltrate throughout the parenchyma. Glomerular enlargement was a common find. Necrosis of tubular cells and haemorrhage were also observed. Analysis of the kidney on a transmission electron microscope allowed a closer look into the necrotic tubular cells, which presented nuclei with condensed chromatin, and loss of cytoplasm. MAIN CONCLUSIONS: Even though the kidney is probably not a primary target of dengue infection in mice, the inoculation of the virus in the blood appears to damage the renal tissue through local inflammation.

Modular 3D-printed fluorometer/photometer for determination of iron(ii), caffeine, and ciprofloxacin in pharmaceutical samples.

The demand for the development of portable and low-cost analytical devices has encouraged studies employing additive manufacturing techniques, such as 3D-printing. This method can be used to produce components such as printed electrodes, photometers, and fluorometers for low-cost systems that provide advantages including low sample volume, reduced chemical waste, and easy coupling with LED-based optics and other instrumental devices. In the present work, a modular 3D-printed fluorometer/photometer was designed and applied for the determination of caffeine (CAF), ciprofloxacin (CIP), and Fe(ii) in pharmaceutical samples. All the plastic parts were printed separately by a 3D printer, using Tritan as the plastic material (black color). The final size of the modular 3D-printed device was 12 × 8 cm. The radiation sources were light-emitting diodes (LEDs), while a light dependent resistor (LDR) was used as a photodetector. The analytical curves obtained for the device were: y = 3.00 × 10-4 [CAF] + 1.00 and R 2 = 0.987 for caffeine; y = 6.90 × 10-3 [CIP] - 3.39 × 10-2 and R 2 = 0.991 for ciprofloxacin; and y = 1.12 × 10-1 [Fe(ii)] + 1.26 × 10-2 and R 2 = 0.998 for iron(ii). The results obtained using the developed device were compared with reference methods, with no statistically significant differences observed. The 3D-printed device was composed of moveable parts, providing flexibility for adaptation and application as a photometer or fluorometer, by only switching the photodetector position. The LED could also be easily switched, permitting application of the device for different purposes. The cost of the device, including the printing and electronic components, was lower than US$10. The use of 3D-printing enables the development of portable instruments for use in remote locations with a lack of research resources.

Primary infection of BALB/c mice with a dengue virus type 4 strain leads to kidney injury

BACKGROUND Dengue is a disease caused by dengue virus (DENV-1 through -4). Among the four serotypes, DENV-4 remains the least studied. Acute kidney injury is a potential complication of dengue generally associated with severe dengue infection. OBJECTIVES The goal of this study was to investigate the alterations caused by experimental dengue infection in the kidney of adult BALB/c mice. METHODS In this study, BALB/c mice were infected through the intravenous route with a DENV-4 strain, isolated from a human patient. The kidneys of the mice were procured and subject to histopathological and ultrastructural analysis. FINDINGS The presence of the viral antigen was confirmed through immunohistochemistry. Analysis of tissue sections revealed the presence of inflammatory cell infiltrate throughout the parenchyma. Glomerular enlargement was a common find. Necrosis of tubular cells and haemorrhage were also observed. Analysis of the kidney on a transmission electron microscope allowed a closer look into the necrotic tubular cells, which presented nuclei with condensed chromatin, and loss of cytoplasm. MAIN CONCLUSIONS Even though the kidney is probably not a primary target of dengue infection in mice, the inoculation of the virus in the blood appears to damage the renal tissue through local inflammation.

The influence of antenna gain and beamwidth used in OSSEUS in the screening process for osteoporosis.

Applications on electromagnetic waves in the field of biotelemetry have increased in the latest years, being used to prevent, diagnose, and treatment of several diseases. In this context, biotelemetry allows minimally invasive monitoring of the physiologic, improving comfort and patient care and significantly reducing hospital costs. Aiming to assist the mineral bone density classification, through a radio frequency signal (RF), for a later diagnosis of osteoporosis, Osseus was proposed in 2018. This equipment is a combination of the application of techniques and concepts of several areas such as software, electrical, electronic, computational, and biomedical engineering, developed at a low cost, with easy access to the population, and non-invasive. However, when placed on evaluation, potential improvements were identified to increase the stability of Osseus operation. It is proposed the implementation of improvements in the antennas used by Osseus, aiming its miniaturization, improvement in the reception of the RF signal, and better stability of the equipment's operation. Then, two antennas were built, one of which was used as a project for the second, which is an array. The array showed significant improvements in the radiation parameters relevant to the application, being a candidate to replace the antennas currently in use at Osseus.

Correction to: Systemic Inflammation as a Driver of Brain Injury: the Astrocyte as an Emerging Player.

The givenname "Paola" of the author Paola Haack Amaral Roppa (Roppa, P.H.A.) should be corrected to read Ricardo Haack Amaral Roppa (Roppa, R.H.A.) as presented above.

Adult-to-Adult Living Donor Liver Transplant: Hemodynamic Evaluation, Prognosis, and Recipient Selection.

BACKGROUND: Living donor liver transplant (LDLT) is a well-established treatment for end-stage liver disease. A better recipient selection and hemodynamic evaluation may improve transplant outcomes. The aim of this study was to establish recipient parameters that could enhance the results of adult-to-adult LDLT. METHODS: We performed a retrospective study of all adult-to-adult LDLTs from a single center between January 2006 and December 2018. Variables analyzed included demographic and clinical parameters, laboratory tests, performance of intraoperative temporary portocaval shunt (TPCS), graft weight/recipient weight ratio (GW/RW), preoperative portal vein thrombosis (PVT), previous major abdominal surgery, and patient survival. Patients were divided in 2 groups according to GW/RW (0.8% cutoff point). RESULTS: A total of 92 adult-to-adult LDLTs were analyzed, encompassing 53 male patients (57.6%). Mean Model for End-Stage Liver Disease score was 13.97 (SD, 4.74), and 57 patients (61.95%) had Child-Pugh-Turcotte score B. Mean GW/RW was 1.1% (SD, 0.37%). Group 1 with GW/RW > 0.8% (n = 74) and group 2 with it ≤ 0.8% (n = 13) presented mean GW/RW of 1.14% (SD, 0.24%) and 0.69% (SD, 0.09%) and P < .01, respectively. Eighteen patients (19.56%) presented PVT, with a worse survival than those without PVT (P = .006). Sixteen patients (17.39%) with previous major abdominal or biliary operations also presented higher mortality (P = .341). Forty-six (50%) intraoperative TPCSs were performed with a better 1- and 3-year patient survival. Receiver operating characteristic curve analysis showed PVT area under the curve of 0.701 (95% CI, 0.526-0.876; P = .018), positive predictive value of 0.69, and negative predictive value of 0.62. Multivariate analysis showed important risk regarding PVT (odds ratio, 6.160; 95% CI, 1.566-24.223; P = .004) and retransplant (odds ratio, 4.452; 95% CI, 0.843-23.503; P = .06). CONCLUSIONS: Better recipient selection without PVT or previous major abdominal surgery, an adequate GW/RW, and intraoperative TPCS with hemodynamic modulation significantly improve outcomes of adult-to-adult LDLT.

Intraoperative Temporary Portocaval Shunt in Liver Transplant.

BACKGROUND: Intraoperative temporary portocaval shunt (TPCS) has been performed during liver transplant to improve hemodynamics and renal function as well as to decrease bleeding during hepatectomy. The aim of this study was to evaluate the impact of TPCS on liver transplant in a long-term single-center study. METHODS: From January 2006 to December 2018, all deceased donor transplants were retrospectively evaluated. Patients were divided in 2 groups: group 1, including those in whom intraoperative TPCS was performed and group 2, including those without TPCS. We analyzed recipient characteristics, survival, mortality, and complication rates in the intraoperative and postoperative periods. RESULTS: A total of 999 deceased donor liver transplants were studied, with 509 patients in group 1 and 490 in group 2. There were 156 cases (15.61%) of preoperative portal vein thrombosis in the whole series. Postoperative renal function (P = .029) as well as length of hospital and intensive care unit stay (P = .0001) were better in group 1. Surgery time and warm ischemia time was also shorter in group 1 (P = .0001). Complications with Clavien-Dindo score ≥ 3 were higher in group 2 (P = .006). Multivariate analysis showed important risk with fulminant hepatitis (odds ratio, 2.127; 95% CI, 1.408-3.213; P < .0001) and Model for End-Stage Liver Disease > 29 (odds ratio, 2.492; 95% CI, 1.862-3.336; P < .0001). Overall survival in group 1 at 1, 5, and 10 years were 78%, 70%, and 68%, respectively. In group 2, they were 70%, 60%, and 58%, respectively (P = .027). CONCLUSIONS: Patients who underwent intraoperative TPCS presented better postoperative renal function, less intraoperative blending, shorter surgical and warm ischemia time, shorter length of hospital and intensive care unit stay, and better overall survival after transplant. Moreover, TPCS should be used patients with severe conditions, such as fulminant hepatitis and Model for End-Stage Liver Disease score > 29.

Calcineurin-Mediated Hippocampal Inflammatory Alterations in Streptozotocin-Induced Model of Dementia.

Although the pathogenesis of Alzheimer's disease (AD) remains unclear, some molecular aspects that precede or accompany the deposit of ß-amyloid in senile plaques attract attention, such as calcium dysregulation and neuroinflammation. It has been suggested that the Ca2+/calmodulin-dependent protein phosphatase, calcineurin (CaN), plays an important role in AD pathogenesis. We hypothesized that CaN activation is involved in the inflammatory changes observed in the streptozotocin (STZ)-induced model of AD. We investigated hippocampal inflammatory and CaN changes in Wistar rats in two moments after intracerebroventricular STZ administration: in the first week (early) and fourth week (later on). We found an early (at 1 week) and persistent (at fourth week) increment in the subunit A of CaN, as well as an increase in the major 48 kDa fragment of this subunit. Glial and inflammatory activation were confirmed by changes of IBA-1, TLR-4, glial fibrillary acidic protein (GFAP), and S100B in the hippocampus. Augmented CaN activity was accompanied by reduced phosphorylation of the pro-apoptotic protein BAD, at Ser 136. Importantly, we found an increase in the nuclear translocation of NFAT4 (more associated to astroglial reactivity) in the hippocampus at 1 and 4 weeks in this model. NFAT3 (more associated with neuronal activation) exhibited an early increase, but decreased later on. Taken together, these data contribute to the understanding of neurochemical changes in the STZ model of sporadic AD, and may explain the persistent inflammatory response in AD, which might occur via the proteolytic activation of CaN, and signaling of NFAT mediated by isoform 4, in activated astrocytes.

Neuroinflammation induced by lipopolysaccharide leads to memory impairment and alterations in hippocampal leptin signaling.

Peripheral inflammation promotes immune-to-brain communication, mediated by cytokines that affect brain activity. Lipopolysaccharide (LPS) has been widely used to mimic systemic inflammation, and the adipokine leptin, released in this condition, modulates hypothalamic leptin receptors (ObR), contributing to sickness behavior. In this study, we used the intracerebroventricular (ICV) route for LPS administration in an attempt to evaluate an acute and direct of this pathogen-associated molecular pattern on leptin-mediated signaling in the hippocampus, where ObR has been implicated in modulating cognitive response. We used bilateral ICV injection of LPS (25 µg/ventricle) in 60-day-old male Wistar rats and the analysis were performed 48 h after surgery. Neuroinflammation was characterized in the LPS group by an increase in concentration of IL-1ß, COX-2 and TLR4 in the hippocampus as well as glial fibrillary acidic protein (GFAP), indicating an astrocyte commitment. Cognitive damage was observed in the animals of the LPS group by an inability to increase the recognition index during the object recognition test. We observed an increase in the concentration of leptin receptors in the hippocampus, which was unaccompanied by changes in the proteins involved in leptin intracellular signaling (p-STAT3 and SOCS3). Moreover, we found a decrease in leptin concentration in the serum of the animals in the LPS group accompanied by an increase in TNF-α levels. Our results showed that neuroinflammation, even in an acute state, can lead to cognitive impairment and may be associated with leptin signaling disturbances in the hippocampus.

Analysis of Macrophage Activation Markers in an Experimental Model of Cutaneous Leishmaniasis Treated with Photodynamic Therapy Mediated by 5-Aminolevulinic Acid.

Objective: In this study, we evaluated the effectiveness of photodynamic therapy (PDT) for the treatment of experimental cutaneous leishmaniasis (CL) and the profile of macrophages activation markers. Background: Leishmaniasis is an infectious disease caused by parasites of the genus Leishmania. CL is caused by Leishmania major in the old world and by Leishmania braziliensis in the Americas. Considering the targeted organs, PDT may constitute a valuable therapeutic intervention. Macrophages are the host cells of Leishmania in mammals and may be classified into type M1 or M2 depending on the pattern of activation. Methods: BALB/c mice were infected in the foot pad with 1 × 106 amastigotes of L. braziliensis and treated with 5-aminolevulinic acid (5-ALA), visible light, or 5-ALA-PDT. The ex vivo mRNA expression levels of interleukin-10, tumor necrosis factor-α (TNF-α), arginase-1, heme oxygenase ( Hmox), and induced nitric oxide synthase (iNOS) were quantities as markers of macrophage activation with distinct ability to kill intracellular parasite. Results: The parasite load decreased significantly in the group treated with PDT compared with the other groups. The iNOS relative mRNA was higher in the group treated with PDT and light only compared with the group without treatment, whereas iNOS/arginase ratio was significantly higher only in the PDT group. The expression of TNF-α was significantly higher in 5-ALA and light compared with PDT and control group. No significant difference was observed in the expression of the other markers evaluated. Conclusions: Both, light and 5-ALA-PDT were able to upregulate iNOS expression only; 5-ALA-PDT was able to reduce parasite burden. The increase in the iNOS levels suggests it might participate in the antimicrobial mechanisms triggered by 5-ALA-PDT; although parasite death mechanism was not completely clarified, the results presented in this study suggest that macrophage activation may contribute to parasite control.

Systemic Inflammation as a Driver of Brain Injury: the Astrocyte as an Emerging Player.

Severe systemic inflammation has strong effects on brain functions, promoting permanent neurocognitive dysfunction and high mortality rates. Additionally, hippocampal damage seems to be directly involved in this process and astrocytes play an important role in neuroinflammation and in the neuroimmune response. However, the contribution of the astrocytes to the pathology of acute brain dysfunction is not well understood. Recently, our group established a protocol for obtaining astrocyte cultures from mature brain to allow the characterization of these cells and their functions under pathologic conditions. The present study was designed to characterize astrocyte function after acute systemic inflammation induced by cecal ligation and perforation (CLP). Hippocampal astrocyte cultures from CLP animals presented increased levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, IL-6, IL-18, and cyclooxygenase-2 and decreased levels of IL-10. This proinflammatory profile was accompanied by an increase in Toll-like receptor (TLR)2 mRNA expression levels and no change either in TLR4 or in vascular endothelial growth factor (VEGF) gene expression. These alterations were associated with increased expressions of p21, nuclear factor kappa B (NFκB), and inducible nitric oxide synthase (iNOS) in astrocytes from CLP animals. The same parameters were also evaluated in whole hippocampal tissue, but differences in this profile were found compared to hippocampal astrocyte cultures from CLP, reflecting an interaction between other central nervous system cell types, which may mask specific astrocytic changes. These results improve our understanding of the mechanisms by which astrocytes react against systemic inflammation, and suggest these cells to be potential targets for therapeutic modulation.

Early and Persistent O-GlcNAc Protein Modification in the Streptozotocin Model of Alzheimer's Disease.

 O-GlcNAc transferase (OGT), an enzyme highly expressed in brain tissue, catalyzes the addition of N-acetyl-glucosamine (GlcNAc) to hydroxyl residues of serine and threonine of proteins. Brain protein O-GlcNAcylation is diminished in Alzheimer's disease (AD), and OGT targets include proteins of the insulin-signaling pathway (e.g., insulin receptor susbtrate-1, IRS-1). We hypothesized that ICV streptozotocin (STZ) also affects O-GlcNAc protein modification. We investigated hippocampal metabolic changes in Wistar rats, particularly OGT levels and insulin resistance, as well as related astroglial activities, immediately after ICV STZ administration (first week) and later on (fourth week). We found an early (at one week) and persistent (at fourth week) decrease in OGT in the ICV STZ model of AD, characterized by a spatial cognitive deficit. Consistent with this observation, we observed a decrease in protein O-GlnNAc modification at both times. Increased phosphorylation at serine-307 of IRS-1, which is related to insulin resistance, was observed on the fourth week. The decrease in OGT and consequent protein O-GlnNAc modifications appear to precede the decrease in glucose uptake and increment of the glyoxalase system observed in the hippocampus. Changes in glial fibrillary acidic protein and S100B in the hippocampus, as well as the alterations in cerebrospinal fluid S100B, confirm the astrogliosis. Moreover, decreases in glutamine synthetase and glutathione content suggest astroglial dysfunction, which are likely implicated in the neurodegenerative cascade triggered in this model. Together, these data contribute to the understanding of neurochemical changes in the ICV STZ model of sporadic AD, and may explain the decreases in protein O-GlcNAc levels and insulin resistance observed in AD.

1,25-Dihydroxyvitamin D3 prevents deleterious effects of homocysteine on mitochondrial function and redox status in heart slices.

Because homocysteine (Hcy) is a risk factor for cardiovascular disease, and vitamin D deficiency can contribute to cardiovascular pathologies. In the present study, we tested the hypothesis that Hcy could impair energy metabolism, mitochondrial function, and redox status in heart slices of Wistar rats and that 1,25-dihydroxivitamin D3 (calcitriol) treatment could prevent such effects. Heart slices were first pretreated with 3 different concentrations of calcitriol (50, 100, and 250nmol/L) for 30minutes at 37°C, after which Hcy was added to promote deleterious effects on metabolism. After 1 hour of incubation, the samples were washed, homogenized, and stored at -80°C before analysis. The results showed that Hcy caused changes in energy metabolism (respiratory chain enzymes), mitochondrial function, and cell viability. Homocysteine also induced oxidative stress, increasing lipid peroxidation, reactive oxygen species generation, and protein damage. An imbalance in antioxidant enzymes was also observed. Calcitriol (50nmol/L) reverted the effect of Hcy on the parameters tested, except for the immunocontent of catalase. Both treatments (calcitriol and Hcy) did not alter the vitamin D receptor immunocontent, which combined with the fact that our ex vivo model is acute, suggesting that the beneficial effect of calcitriol occurs directly through antioxidative mechanisms and not via gene expression. In this study, we show that Hcy impairs mitochondrial function and induces changes in the redox status in heart slices, which were reverted by calcitriol. These findings suggest that calcitriol may be a preventive/therapeutic strategy for complications caused by Hcy.

Hippocampal changes in STZ-model of Alzheimer's disease are dependent on sex.

The majority of Alzheimer's disease (AD) cases are sporadic and aging is the major risk factor for developing the disease, affecting more women than men. In spite of different gender prevalence, most experimental studies in animal models have been performed in male. This study investigates the streptozotocin (STZ)-induced AD model at three different times (2, 4 and 8 weeks afterwards) and in male and female rats, evaluating cognitive deficit, cholinergic neurotransmission, glucose uptake, glutathione content and specific glial markers (GFAP and S100B protein) in the hippocampus of the rat. Our data reinforce the relevance of alterations in STZ model of dementia, reported in the genesis and/or progression of AD such as cholinergic deficit and glucose uptake decrease. All alterations in these parameters (except GFAP) were dependent on sex. It is unclear, at this moment, which alterations are due to sex steroid modulation. In spite of limitations of this experimental model, these data may contribute to understand AD susceptibility and progression dependent on sex.