Brazilian Journal of Medical and Biological Research最新文献

The objective of the present study was to compare and test the applicability of different protocols for accessing aerobic capacity in Sprague Dawley rats using treadmill running. Fifteen 70-day-old adult Sprague Dawley rats (270-290 g) were used. After 5 days of adaptation to the treadmill, the animals underwent 7 days of evaluations with a 48-h interval between each protocol. On the first two days, they underwent, in random order, a graded exercise test, with (GXT2) or without (GXT1) blood sample collections to determine blood lactate concentrations and the anaerobic threshold. In the subsequent 4 days, they underwent continuous 30-min efforts to determine the maximal lactate steady state (MLSS) with the intensity prescribed in percentages of the maximum speed (MaxS) obtained in GXT1, and on the last day they underwent the minimum lactate (ML) protocol. The MaxS obtained in GXT2 was higher than in GXT1, and there was a moderate correlation (r=0.614, P=0.011) between them. In many cases, lactate and glucose blood concentrations did not show the expected kinetics, making aerobic capacity determination impossible using these protocols. MLSS showed a higher success rate compared to other protocols (MLSS=80%; GXT2=47%; ML=60%). In conclusion, with the MLSS protocol, it is only possible to measure time to exhaustion at each intensity, which does not exactly reflect aerobic capacity, and the use of blood lactate and glucose concentrations to evaluate the aerobic capacity of rats in incremental and ML treadmill running protocols is still discouraged.

Immune checkpoint blockade with anti-programmed cell death protein 1 (PD-1) antibody has become a hot topic for the treatment of human malignancies. Here, we aimed to investigate whether the percentage of PD-1 in CD8+ tumor-infiltrating lymphocytes correlates with the progression of colonic-derived peritoneal adenocarcinoma (PA). Peripheral blood and tissue samples from 40 patients with colonic-derived PA were collected and subjected to multicolor flow cytometry analysis of the percentage of peripheral PD-1+CD8+ T cells. The multiple immunofluorescence method was used to detect the positive percentages of PD-1 and CD8 in the tissues. The enrolled patients were divided into groups by recurrence interval (less than 6 months, greater than two years) and differentiation grade (low, well/moderate). In the colonic-derived PA tissues, the percentages of cells positive for PD-1, CD8, and PD-1+CD8+ were higher in the paracancer tissues compared with cancerous tissues. PD-1+CD8+ T cells had an increased presence in peripheral blood than in tissues. Our data also indicated that colonic-derived PA patients with less than a six-month recurrence interval presented higher levels of PD-1 in CD8+ tumor-infiltrating lymphocytes in than the two-year recurrence group. The level of PD-1+CD8+T cells in the tissue correlated with the clinical outcome of colonic-derived PA. Higher percentages of PD-1+CD8+T cells correlated with a shorter progression-free survival (PFS). PD-1 in CD8+ tumor-infiltrating lymphocytes may have a good predictive value for immunotherapy of colonic-derived PA and act as the prognostic factor for PFS.

Oral tolerance is an immunological phenomenon that results from protein intake and that has systemic effects on inflammation. Previous research has shown that parenteral injection of tolerated proteins reduces inflammatory infiltrate and improves skin wound healing. Herein, we tested whether the injection of tolerated proteins improves the healing of several wounds on different parts of the body, such as on the skin of the back and on the external ear (the auricle). To induce oral tolerance to ovalbumin (OVA), eight-week old C57BL/6 mice drank egg white diluted 1:5 in water for 3 consecutive days. The control mice drank water. Seven days after oral treatment, mice were submitted to excisional injuries on the skin of the back (6 mm) and ears (4 mm). Minutes before the injuries, the mice received an intraperitoneal injection of OVA + Al(OH)3. Seven and 40 days after the injuries, tissue samples were collected and processed for histological analysis of the wounds. The results showed that the injection of OVA in animals that drank OVA reduced the inflammatory infiltrate in all lesions. In addition, injection of OVA in animals that drank OVA promoted better organization of the extracellular matrix, with thicker and intertwined collagen fibers in the neodermis, resulting in smaller scars on the skin. Furthermore, the healing area of the ears of OVA-tolerant animals showed chondrocyte aggregates and less obvious fibrous scar tissue compared with control animals. In conclusion, systemic effects of oral tolerance positively influenced the healing of several lesions on different parts of the body.

Oleanolic acid (OA) is recognized for its anticancer properties, which are similar to those of conventional chemotherapeutic agents used in clinical practice. However, its role in modulating the sensitivity of cancer cells to fluorouracil (5FU) has not yet been documented. This study aimed to examine the effects of OA and 5FU co-administration on hepatocellular carcinoma (HCC) and uncover the mechanisms involved. In this study, the efficacy of combination therapy with OA and 5FU in treating HCC was evaluated using the MTT cell proliferation assay, plate clone formation assay, Hoechst 33342 staining, western blot assay, and Ca2+ fluorescence probe. The results demonstrated that compared with the use of OA or 5FU alone, OA and 5FU combination therapy significantly inhibited the proliferation of HEPG2 cells and enhanced cell apoptosis and Ca2+ levels in HCC. Additionally, the inhibitory effect of OA and 5FU combination therapy on cell proliferation and apoptosis was partially reversed by the calcium channel blocker 2-aminoethyldiphenyl borate (2-APB). In summary, these findings indicated that synergistic treatment with OA and 5FU can enhance cell apoptosis, inhibit cell proliferation, and regulate Ca2+ signaling in HCC, providing new guidance for the clinical treatment of HCC.

Liraglutide (LIRA) is an agonist of the GLP-1 receptor used in the treatment of type 2 diabetes with a cardioprotective effect, although little is known about the effects of LIRA in post-menopause. We aimed to evaluate the effects of LIRA in the cardiovascular system of ovariectomized spontaneously hypertensive rats (SHR). SHR rats were separated into two groups: ovariectomized (saline) and ovariectomized + liraglutide (0.6 and 1.2 mg/kg for 4+4 weeks, respectively). Systolic blood pressure (SBP) was indirectly evaluated at the beginning and end of treatment. Diastolic, systolic, and mean blood pressure were evaluated in the carotid artery of anesthetized animals, while left ventricle systolic blood pressure (LVSBP) and left ventricle derivatives (-dP/dt; +dP/dt) were evaluated in the left ventricle. An oral glucose tolerance test (GTT) was conducted. Antioxidant enzymes and calcium-handling proteins were analyzed in heart tissue by western blot. Treatment with LIRA increased the expression of antioxidant enzymes (superoxide dismutase (SOD2) and catalase). No changes were observed in the GTT, cardiac hemodynamics, blood pressure, and calcium-handling protein expression. A decrease in visceral fat depot was observed without changes in final body weight. LIRA induced an antioxidant subclinical effect in ovariectomized SHR female rats without changing glucose metabolism and cardiac blood pressure.

Axons of dopaminergic neurons projecting from substantia nigra to striatum are severely affected in the early stage of Parkinson's disease (PD), with axonal degeneration preceding the loss of cell bodies. Our previous study indicated that the dysfunctional retrograde axonal transport could lead to the death of dopaminergic neurons resulting in PD (10.1111/j.1471-4159.2008.05526.x). However, dynein, as the main molecule involved in retrograde axonal transport, was not affected. This study aimed to verify the hypothesis that dynactin rather than dynein may be one of the key factors in the retrograde degeneration of dopaminergic neurons in the early stage of PD. Dynactin morpholino was used to inhibit the expression of dynactin in transgenic (Vmat2:GFP) zebrafish, resulting in a significant decrease of diencephalon dopamine neurons and synuclein aggregation in the basal plate region. In the dopaminergic SH-SY5Y cell line, dynactin-siRNA knockdown resulted in the expression of dynein shifting from dispersed distribution to concentration in synapses and cytoplasm near axons, and the fusion rate of dynein to dynactin was decreased, especially in axons, which blocked the retrograde axonal transport of α-synuclein and autophagy flow. Our results linked the knockdown of dynactin gene to the dysfunction of axonal microtubule transport system, suggesting that dynactin may be one of the key factors contributing to the retrograde degeneration of dopaminergic neurons in the early stage of PD.

Cellular senescence is an important cause of age-related degenerative diseases, including osteoarthritis (OA). Chondrocyte senescence is crucial in OA onset and progression. As a non-invasive, safe, and widely used physical rehabilitation factor, the effect and mechanism of low intensity pulsed ultrasound (LIPUS) on chondrocyte senescence remain unclear. This study evaluated the inhibitory effect of LIPUS on OA chondrocyte senescence in vitro and in vivo. The effect of LIPUS on chondrocyte senescence was examined by RT-qPCR, enzyme-linked immunosorbent assay (ELISA), and western blotting. Changes in levels of reactive oxygen species (ROS) and γ-h2ax foci in senescent chondrocytes were detected using fluorescent staining. Chondrocyte senescence was evaluated by senescence-associated β-galactosidase (SA-β-gal) staining. The PI3K inhibitor LY294002 and the PI3K agonist 740Y-P were used to investigate whether PI3K/AKT/mTOR signalling was involved in the effect of LIPUS in senescent chondrocytes. Chondrocyte senescence and cartilage degeneration were analyzed in a destabilization of the medial meniscal (DMM) mouse model by immunohistochemistry, hematoxylin and eosin staining, and safranin-O/fast green staining. LIPUS inhibited the expression of the senescence-associated secretory phenotype (SASP) factors CCL4 and CCL2 and the senescence phenotype in doxorubicin-treated chondrocytes by inhibiting the PI3K/AKT/mTOR pathway. LIPUS alleviated chondrocyte senescence and attenuated OA progression in the DMM mice. These results demonstrated a novel role for LIPUS in inhibiting chondrocyte senescence and the SASP by modulating PI3K/AKT/mTOR signalling. Our findings expanded the clinical application of LIPUS and provide a new, non-invasive, and safe treatment approach to prevent and treat age-related degenerative joint disorders.

Rapid dissemination of Klebsiella pneumoniae carbapenemase (KPC) is a leading cause of treatment failure, significantly increasing morbidity and mortality rates among inpatients, particularly in the intensive care unit (ICU). This study aimed to detect the occurrence of carbapenemase- and carbapenem-resistant-encoding genes in K. pneumoniae isolates from COVID-19 positive and negative patients, and to assess their impact on patient outcomes. A prospective analysis was conducted at a tertiary care hospital in Saudi Arabia, collecting 97 carbapenem-resistant K. pneumoniae (CRKP) isolates from patients with COVID-19 during 2020-2021. Isolates were obtained from various clinical specimens. Antimicrobial susceptibility assays were performed using the Automated Vitek-2 system, and data were analyzed using IBM SPSS Statistics. The predominant carbapenemases identified were Oxacillinase-48 (OXA-48), followed by KPC and New Delhi metallo-β-lactamase (NDM), with Imipenemase (IMP) and Verona integron-encoded metallo-β-lactamase (VIM) being the least prevalent. COVID-19 did not significantly affect the distribution of these genes (P>0.05); however, COVID-19 status and age over 60 years significantly impacted the outcomes of CRKP patients. Other factors such as gender, total ICU or ward stay, and comorbidities did not significantly affect CRKP infection outcomes. The most common carbapenem-resistant genes identified were blaKPC, blaNDM, and blaOXA-48; however, they were not significantly associated with increased mortality.

Low back pain (LBP) is a common type of pain that causes disability and impairs cognitive function. With over 80% of adults estimated to experience LBP during their lifetime, this type of pain not only has a significant impact on the individual, but also on public health systems and national economies. Unfortunately, there is no single standard of care for patients with LBP. N-acetylcysteine (NAC), which is used clinically to treat acetaminophen overdose, has recently been tested as a potential treatment for LBP. NAC is inexpensive and commercially available, and it has an established tolerance and safety profile. However, NAC's efficacy in LBP has not been established. This scoping review presents a summary of studies investigating the effects of NAC and the potential benefits in LBP treatment, and highlights its potential molecular mechanisms and side effects. A systematic literature search in Pubmed/MEDLINE, Embase, Scopus, Science Direct, Web of Science, Cinahl, and Lilacs databases was conducted. The PRISMA-ScR checklist was used to ensure integrity of the review. The scoping review protocol was registered in the Open Science Framework. No limit was set on study language and publication date. In total, 2357 articles were located, of which 16 were included. The studies show that NAC has potential for LBP treatment, but data are derived only from a few clinical trials and preclinical studies. Thus, there is much to learn and more clinical studies should be performed before NAC can be clinically recommended for the treatment of LBP.

The COVID-19 pandemic has caused a global crisis, overwhelming hospitals and intensive care units (ICU) and leading to an increase in nosocomial infections due to prolonged hospitalization and other risk factors. The present study evaluated the prevalence of secondary fungal infections in critically ill patients with COVID-19. This is a retrospective, single-center study conducted in a hospital in northeastern Brazil, which evaluated 1,364 medical records of patients admitted to a COVID-19 ICU during 2020 and 2021. A total of 327 pathogenic yeasts were isolated from 132 (40.4%) respiratory, 70 (21.4%) blood, 124 (37.9%) urine, and one (0.3%) surgical wound samples. Fungal infections were diagnosed in the intermediate (5 to 12 days) or late (≥12 days) stage of hospitalization. The most frequent yeast isolated from critically ill COVID-19 patients was Candida albicans [126 (67.7%) and 60 (42.6%)], followed by Candida tropicalis [25 (13.4%) and 39 (27.7%)]. Candida parapsilosis isolates increased 5.7-fold in 2021 [40 (28.4%)] compared to 2020 [7 (3.8%)]. The least frequently isolated in 2020 and 2021 were Nakaseomyces glabratus [4 (2.2%) and 1 (0.7%)], and Pichia kudriavzevii, which was isolated only in 2021 (1 (0.7%)). During the study period, a decrease in susceptibility to antifungals was observed: susceptibility to voriconazole reduced from 100 to 77.2%, to flucytosine from 99.4 to 78.8%, and to micafungin from 99.4 to 83.6%. The changes in the frequency of species causing secondary infections in critically ill COVID-19 patients and susceptibility to the antifungals indicate the need for early and adequate diagnosis to minimize negative outcomes.