Can SARS-CoV-2 infect the central nervous system via the olfactory bulb or the blood-brain barrier?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China in December 2019. On February 11, the World Health Organization (WHO) announced the name for the new illness caused by SARS-CoV-2: COVID-19. By March 11, the outbreak of COVID-19 was declared a pandemic by the WHO. This virus has extensively altered daily life for many across the globe, while claiming hundreds of thousands of lives. While fundamentally a respiratory illness, many infected individuals experience symptoms that involve the central nervous system (CNS). It is likely that many of these symptoms are the result of the virus residing outside of the CNS. However, the current evidence does indicate that the SARS-CoV-2 virus can use olfactory neurons (or other nerve tracts) to travel from the periphery into the CNS, and that the virus may also enter the brain through the blood-brain barrier (BBB). We discuss how the virus may use established infection mechanisms (ACE2, NRP1, TMPRSS2, furin and Cathepsin L), as well mechanisms still under consideration (BASIGIN) to infect and spread throughout the CNS. Confirming the impact of the virus on the CNS will be crucial in dealing with the long-term consequences of the epidemic.

Symptomatic Intrathecal Hematoma following an Epidural Blood Patch for an Obstetric Patient with Postdural Puncture Headache: A Case Report and Synthesis of the Literature.

Epidural blood patch (EBP), generally considered a low-risk procedure, can potentially lead to significant neurological complications. We report the case of a parturient who underwent an uneventful EBP for postdural puncture headache (PDPH) and subsequently presented with progressively worsening radicular symptoms. Magnetic resonance imaging (MRI) revealed an intrathecal hematoma, and conservative management with steroids led to complete recovery. Our case highlights the possibility of this rare complication following an uneventful procedure and the importance of prompt diagnosis and treatment to prevent serious adverse outcomes. Literature review, EBP alternatives, and strategies to minimize complications following blood patch will be discussed in this report.

Amyloid Beta 25-35 induces blood-brain barrier disruption in vitro.

The amyloid ß-peptide (Aß) is transported across the blood-brain barrier (BBB) by binding with the receptor for advanced glycation end products (RAGE). Previously, we demonstrated that the Aß fraction 25-35 (Aß25-35) increases RAGE expression in the rat hippocampus, likely contributing to its neurotoxic effects. However, it is still debated if the interaction of Aß with RAGE compromises the BBB function in Alzheimer' disease (AD). Here, we evaluated the effects of Aß25-35 in an established in vitro model of the BBB. Rat brain microvascular endothelial cells (rBMVECs) were treated with 20 µM active Aß25-35 or the inactive Aß35-25 (control), for 24 h. Exposure to Aß25-35 significantly decreased cell viability, increased cellular necrosis, and increased the production of reactive oxygen species (ROS), which triggered a decrease in the enzyme glutathione peroxidase when compared to the control condition. Aß25-35 also increased BBB permeability by altering the expression of tight junction proteins (decreasing zonula occludens-1 and increasing occludin). Aß25-35 induced monolayer disruption and cellular disarrangement of the BBB, with RAGE being highly expressed in the zones of disarrangement. Together, these data suggest that Aß25-35-induces toxicity by compromising the functionality and integrity of the BBB in vitro. Graphical abstract Aß25-35 induces BBB dysfunction in vitro, wich is likely mediated by OS and ultimately leads to disruption of BBB integrity and cell death.

Cytotoxicity profile of pristine graphene on brain microvascular endothelial cells.

Graphene-based nanomaterials hold the potential to be used in a wide variety of applications, including biomedical devices. Pristine graphene (PG) is an un-functionalized, defect-free type of graphene that could be used as a material for neural interfacing. However, the neurotoxic effects of PG, particularly to the blood-brain barrier (BBB), have not been fully studied. The BBB separates the brain tissue from the circulating substances in the blood and is essential to maintain the brain homeostasis. The principal components of the BBB are brain microvascular endothelial cells (BMVECs), which maintain a protectively low permeability due to the expression of tight junction proteins. Here we analyzed the effects of PG on BMVECs in an in vitro model of the BBB. BMVECs were treated with PG at 0, 10, 50 and 100 µg/mL for 24 hours and viability and functional analyses of BBB integrity were performed. PG increased lactate dehydrogenase release at 50 and 100 µg/mL, suggesting the induction of necrosis. Surprisingly, 2,3,-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)-carbonyl]-2H-tetrazolium (XTT) conversion was increased at 10 and 50 µg/mL. In contrast, XTT conversion was decreased at 100 µg/mL, suggesting the induction of cell death. In addition, 100 µg/mL PG increased DNA fragmentation, suggesting induction of apoptosis. At the same time, 50 and 100 µg/mL of PG increased the endothelial permeability, which corresponded with a decrease in the expression of the tight junction protein occludin at 100 µg/mL. In conclusion, these results suggest that PG negatively affects the viability and function of the BBB endothelial cells in vitro.

Evaluation of cardiovascular responses to silver nanoparticles (AgNPs) in spontaneously hypertensive rats.

Silver nanoparticles (AgNPs) are used in the medical, pharmaceutical and food industry. Adverse effects and toxicity induced by AgNPs upon cardiac function related to nitric oxide (NO) and oxidative stress (OS) are described. AgNPs-toxicity may be influenced by cardiovascular pathologies such as hypertension. However, the molecules involved under pathophysiological conditions are not well studied. The aim of this work was to evaluate perfusion pressure (PP) and left ventricle pressure (LVP) as physiological parameters of cardiovascular function in response to AgNPs, using isolated perfused hearts from spontaneously hypertensive rats (SHR), and identify the role of NO and OS. The results suggest that AgNPs reduced NO derived from endothelial/inducible NO-synthase and increased OS, leading to increased and sustained vasoconstriction and myocardial contractility. Additionally, the hypertension condition alters phenylephrine (Phe) and acetylcholine (ACh) classic effects. These data suggest that hypertension intensified AgNPs-cardiotoxicity. Nevertheless, the precise mechanism of action is still under elucidation.

Effect of silver nanoparticles upon the myocardial and coronary vascular function in isolated and perfused diabetic rat hearts.

Silver nanoparticles (AgNPs) are promising antibacterial nanomaterials for diagnostic and treatment of diabetes. However, toxicity and adverse cardiac responses induced by AgNPs related to nitric oxide (NO) and oxidative stress (OS) are described. Moreover, little is known about the diabetes influence upon AgNPs-toxicity. The aim of this work was to evaluate cardiovascular function in response to AgNPs through measuring perfusion pressure (PP) and left ventricle pressure (LVP), using perfused hearts from streptozotocin (STZ)-induced diabetic rats and identify the role of NO and OS. High concentrations but not the lower concentrations of AgNPs, promotes increases in PP and LVP, as well as increased OS. Additionally, diabetes alters the classic effects of phenylephrine (Phe) and acetylcholine (ACh). These data suggest that diabetes may intensify AgNPs-cardiotoxicity. Nevertheless, the precise mechanism of action is still under elucidation.

Evaluation of vascular tone and cardiac contractility in response to silver nanoparticles, using Langendorff rat heart preparation.

Silver nanoparticles (AgNPs) have been widely used because of their antimicrobial properties. However, several reports suggest that AgNPs exposure promote cardiac effects that involve nitric oxide (NO) and oxidative stress (OS). Nevertheless, there are no studies related to AgNPs-induced effects in cardiac physiology. The aim of this study was to evaluate the AgNPs direct actions on coronary vascular tone and cardiac contractility using Langendorff rat heart preparation. Low concentrations of AgNPs (0.1 and 1 µg/mL) increased NO derived from inducible NO-synthase (iNOS), without modifying cardiac parameters. Meanwhile, high concentrations (10 and 100 µg/mL) promoted a sustained vasoconstriction and increased cardiac contractility related to OS, leading to rhabdomyolysis. Furthermore, AgNPs were internalized in the cardiac muscle, hindering classic actions induced by phenylephrine (Phe) and acetylcholine (ACh). These data suggest that AgNPs affect cardiac physiology in function of the concentration and in part of the NO generation, NOS expression and OS.

Role of silver nanoparticles (AgNPs) on the cardiovascular system.

With the advent of nanotechnology, the use and applications of silver nanoparticles (AgNPs) have increased, both in consumer products as well as in medical devices. However, little is known about the effects of these nanoparticles on human health, more specific in the cardiovascular system, since this system represents an important route of action in terms of distribution, bioaccumulation and bioavailability of the different circulating substances in the bloodstream. A collection of studies have addressed the effects and applications of different kinds of AgNPs (shaped, sized, coated and functionalized) in several components of the cardiovascular system, such as endothelial cells, isolated vessels and organs as well as integrative animal models, trying to identify the underlying mechanisms involved in their actions, to understand their implication in the field of biomedicine. The purpose of the present review is to summarize the most relevant studies to date of AgNPs effects in the cardiovascular system and provide a broader picture of the potential toxic effects and exposure risks, which in turn will allow pointing out the directions of further research as well as new applications of these versatile nanomaterials.

The prolactin family hormones regulate vascular tone through NO and prostacyclin production in isolated rat aortic rings.

AIM: Prolactin family hormones include growth hormone, placental lactogen and prolactin, which are able to regulate angiogenesis via NO and prostaglandins. However, their effects on vascular tone are not fully understood. The aim of this study was to evaluate the effects of prolactin family hormones on rat vascular tone in vitro. METHODS: Aortic rings were prepared from adult male rats and precontracted with phenylephrine, then treated with the hormones and drugs. The tension was measured with isometric force displacement transducer connected to a polygraph. NO production and prostacyclin release in physiological solution was determined. Cultured rat aortic endothelial cells (RAECs) were treated with the hormones and drugs, and the phosphorylation of eNOS at serine 1177 was assessed using Western bolt analysis. RESULTS: Administration of growth hormone or placental lactogen (0.01-100 nmol/L) induced endothelium-dependent vasodilation. Both the hormones significantly increased the phosphorylation of eNOS in RAECs and NO level in physiological solution. Preincubation with L-NAME blocked growth hormone- or placental lactogen-induced vasodilation and NO production. Preincubation with an antibody against growth hormone receptors blocked growth hormone- and placental lactogen-induced vasodilation. Addition of a single dose of prolactin (0.01 nmol/L) induced sustained vessel relaxation, whereas multiple doses of prolactin induced a biphasic contraction-relaxation effect. The vascular effects of prolactin depended on endothelium. Prolactin significantly increased the level of prostacyclin I2 in physiological solution. Preincubation with indomethacin or an antibody against prolactin receptors blocked prolactin-induced vasodilation. CONCLUSION: The prolactin family hormones regulate rat vascular tone, selectively promoting either relaxation or contraction of vascular smooth muscle via activation of either growth hormone receptors or prolactin receptors within the endothelium.

An analysis of 2 fusion methods for the treatment of osteomyelitis following fractures about the ankle.

BACKGROUND: In the setting of chronic osteomyelitis following fractures about the ankle, reconstruction through bony arthrodesis may be used as a reconstructive alternative to amputation. During these cases, surgeons often avoid using internal fixation in an attempt to avoid reinfection or premature hardware failure. In this retrospective review, we analyzed the outcomes of chronic osteomyelitic patients who had an arthrodesis of the ankle using either internal or external fixation, focusing on salvage rates, infection clearance, union rates, and functional outcomes. No device was implanted into a known active infection. METHODS: We performed a retrospective chart review of adult patients undergoing arthrodesis in the setting of a previously septic ankle following a traumatic injury. In each case, multiple irrigation and debridement procedures and local and systemic antibiotics were used. Infection status was determined by clinical exam, MRI, nuclear medicine studies, and ultimately bone biopsies. No fixation device was implanted in ankles with known active infections. Patients were divided into 2 cohorts: those fused with internal devices and those fused with external fixators. Thirty patients underwent a total of 32 arthrodesis procedures. Mean follow up time was 27 months (range, 6 to 144). RESULTS: Nineteen fusions were performed using internal fixation; only 2 required amputations, therefore limb salvage was 90%. Fifteen were able to ambulate with or without the assistance of an orthosis (79%). Four patients experienced recurrent infection (21%) and 5 developed nonunion (26%). Of the 13 fusions performed with external fixators, only 1 required an amputation, putting limb salvage at 92%. Ten patients were able to walk with or without the assistance of an orthosis as their final functional status (77%). Two patients experienced recurrent infection (15%), and 4 went on to nonunion (31%). CONCLUSION: When analyzing these 2 fusion methods in posttraumatic patients with previously septic ankles, with the numbers available both methods achieved similar rates of limb salvage and final functional status in these patients, as well as similar rates of infection clearance and bony union. As internal fixation is often less labor-intensive for the surgeon and more palatable for the patient postoperatively, we encourage surgeons to consider arthrodesis with internal fixation once the infection is successfully eradicated, especially in a noncompliant patient population. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Silver nanoparticles induce anti-proliferative effects on airway smooth muscle cells. Role of nitric oxide and muscarinic receptor signaling pathway.

Silver nanoparticles (AgNPs) are used to manufacture materials with new properties and functions. However, little is known about their toxic or beneficial effects on human health, especially in the respiratory system, where its smooth muscle (ASM) regulates the airway contractility by different mediators, such as acetylcholine (ACh) and nitric oxide (NO). The aim of this study was to evaluate the effects of AgNPs on ASM cells. Exposure to AgNPs induced ACh-independent expression of the inducible nitric oxide synthase (iNOS) at 100 µg/mL, associated with excessive production of NO. AgNPs induced the muscarinic receptor activation, since its blockage with atropine and blockage of its downstream signaling pathway inhibited the NO production. AgNPs at 10 and 100 µg/mL induced ACh-independent prolonged cytotoxicity and decreased cellular proliferation mediated by the muscarinic receptor-iNOS pathway. However, the concentration of 100 µg/mL of AgNPs induced muscarinic receptor-independent apoptosis, suggesting the activation of multiple pathways. These data indicate that AgNPs induce prolonged cytotoxic and anti-proliferative effects on ASM cells, suggesting an activation of the muscarinic receptor-iNOS pathway. Further investigation is required to understand the full mechanisms of action of AgNPs on ASM under specific biological conditions.

Prolactin and blood-brain barrier permeability.

The blood-brain barrier (BBB) consists in part of a highly specialized set of cells which separates the brain from the vascular system. The BBB controls the entry and exit of substances from the brain tissue through tight junctions (TJs) between endothelial cells. It is known that the hormone prolactin (PRL) is able to regulate endothelial-dependent processes, like the balance between proliferation and apoptosis and the mammary epithelial permeability. However, the effects of PRL and the role it plays in the BBB permeability are still not well understood. A primary culture of bovine brain microvessel endothelial cells was used as in vitro model of BBB. Cells were treated with PRL (0.1, 1, 10 and 100 nM) for 24 hours. PRL significantly increased cellular proliferation at 10 and 100 nM, but did not modify basal apoptosis. These effects were dependent on the production of the mitogenic factor nitric oxide (NO). PRL significantly decreased the permeability and promoted an increase in trans-endothelial electrical resistance in a NO-independent way. PRL also increased the expression of the TJs proteins claudin-5 and occludin. The short form of the PRL receptor was detected in these cells but its expression was not modified by PRL. Together, these results suggest that PRL has the ability to increase cellular proliferation associated with a decrease on BBB permeability by increasing the expression of TJs proteins.

Nicotine alters the expression of molecular markers of endocrine disruption in zebrafish.

Nicotine, a drug of abuse, has been reported to have many adverse effects on the developing nervous system. In rodents, chronic nicotine exposure inhibits estrogen-mediated neuroprotection against cerebral ischemia in females suggesting that nicotine could disrupt endocrine targets. Zebrafish have been used as a model system for examining mechanisms underlying nicotinic effects on neuronal development. Here, using zebrafish embryos, we demonstrate that nicotine alters the expression of the validated endocrine disruption (ED) biomarkers, vitellogenin (vtg 1 and vtg 2) and cytochrome p450 aromatase (cyp19a1a and cyp19a1b) at the transcriptional level. Increased expression of three of these molecular markers (vtg 1, vtg 2 and cyp19a1b) in response to 17ß-estradiol (E2) was more pronounced in 48hpf (hours post-fertilization) embryos than in the 24hpf embryos. While 24hpf embryos were non-responsive in this regard to 25µM nicotine, a similar exposure of the 48hpf embryos for 24h significantly down-regulated the expression of all four ED biomarker genes indicating that nicotine's anti-estrogenic effects are detectable in the 48hpf zebrafish embryos. These results provide direct molecular evidence that nicotine is an endocrine disruptor in zebrafish.

Radiosensitization induced by the anti-epidermal growth factor receptor monoclonal antibodies cetuximab and nimotuzumab in A431 cells.

Epidermal growth factor receptors (EGFR) are overexpressed in a wide range of malignancies including head and neck, colon, and breast cancers. It has been identified that carcinomas with high expression levels of EGFR are more resistant to radiotherapy. Therefore, inhibiting nuclear translocation of EGFR to increase the radiosensitivity of malignant cells expressing EGFR offers the potential for increasing the therapeutic index of radiotherapy. The purpose of the present study was to quantify and to compare the radiosensitizing properties of the well-known anti-EGFR antibodies, cetuximab and nimotuzumab in human epidermoid A431 overexpressing EGFR cells. Cells were treated with two concentrations of the antibodies and then irradiated with a single dose of 4 Gy. The results indicated that the two antibodies induced radiosensitization increasing the percentage of dead/dying cells and the yield of γ-H2AX foci 24 h after irradiation. Whereas cetuximab exhibited a significant increase in radiosensitization at the highest concentration, the effects of nimotuzumab were more modest. A correlation between γ-H2AX foci signals and dead/dying cells was observed. The disparity in modulation of radiation-induced DNA damage by the two antibodies could be associated with the level of their respective intrinsic cytotoxic properties. Overall, the findings highlight the potential therapeutic benefit of combination therapy with anti-EGFR antibodies and radiotherapy for relevant carcinomas.

Effect of 45 nm silver nanoparticles (AgNPs) upon the smooth muscle of rat trachea: role of nitric oxide.

AgNPs have been used to manufacture nanomaterials with new biophysical properties and functions. However, few experimental approaches have been used to assess their potential toxic or beneficial effects on human health, in association with the size, concentration, and biological target. The aim of this work was to evaluate the effects of the AgNPs on the smooth muscle of rat trachea. A single administration of AgNPs did not modify the smooth muscle tone, but, when the trachea rings were pre-treated with acetylcholine (ACh), AgNPs produced a contractile effect. Simultaneous administration of AgNPs and ACh resulted in a slight increase of smooth muscle contractility induced by ACh. AgNPs pretreatment followed by ACh administration showed that AgNPs exerted an important contraction effect induced by ACh after which muscle tone did not return to the basal level. This effect was associated with an increase in the production of nitric oxide (NO). The contractile response of the AgNPs induced by ACh was completely blocked when the rings were incubated, after the ACh but before the AgNPs administration, with 1400 W (NO blocker). The contractile effect was also abolished by atropine, which suggests that AgNPs alter ACh muscarinic receptor signaling. These data also show that AgNPs modify the contractile action of ACh through NO production and possibly induce hyper-reactivity of tracheal smooth muscle.

Evaluación del control de pacientes hipertensos dispensarizados en dos municipios de ciudad de la Habana / Assessment for controlling hypertensive patients in outpatient care at two municipies at City of Havana

Se entrevistaron 756 hipertensos, dispensarizados en 54 consultorios del médico de la familia, de los municipios 10 de Octubre y Guanabacoa, con el propósito de evaluar el control de la enfermedad a este nivel y precisar los factores que influyen cuando no se logra normalizar las cifras tensionales de estos pacientes. Los datos se analizaron con el estadígrafo chi-cuadrado. Se encontró sólo un 16,4 por ciento controlado y un 11,3 por ciento parcialmente controlado. Sólo la hiperlipidemia influyó significativamente en el grupo no controlado (p<0,05). Predominó el tratamiento no farmacológico incorrecto, significativo en el grupo no controlado (p<0,05). El 80,2 por ciento consumía medicamentos (56 por ciento cumplidores, no controlados). Se concluye que las conductas terapéuticas influyen en la falla de control de la tensión arterial, si se trabaja para modificar dichas conductas junto con los factores de riesgo, se podrá incrementar el número de pacientes controlados (AU)

Evaluación del control de pacientes hipertensos dispensarizados en dos municipios de Ciudad de La Habana

Se entrevistaron 756 hipertensos, dispensarizados en 54 consultorios del médico de la familia, de los municipios 10 de Octubre y Guanabacoa, con el propósito de evaluar el control de la enfermedad a este nivel y precisar los factores que influyen cuando no se logra normalizar las cifras tensionales de estos pacientes. Los datos se analizaron con el estadígrafo chi-cuadrado. Se encontró sólo un 16,4 % controlado y un 11,3 % parcialmente controlado. Sólo la hiperlipidemia influyó significativamente en el grupo no controlado (p < 0,05). Predominó el tratamiento no farmacológico incorrecto, significativo en el grupo no controlado (p < 0,05). El 80,2 % consumía medicamentos (56 % cumplidores, no controlados). Se concluye que las conductas terapéuticas influyen en la falta de control de la tensión arterial, si se trabaja para modificar dichas conductas junto con los factores de riesgo, se podrá incrementar el número de pacientes controlados.

Características de la citoprotección con dietilcarbamacina: estudio comparativo con otras drogas / Characteristics of cytoprotecction with diethylcarbaazine: compative study with other drugs

Se estudiaron los efectos de la administración prolongada de citrato de dietilcarbamacina (DECC) en la citoprotección gástrica inducida por esta droga en el modelo de lesiones provocadas por etanol 96

(1 mL intragástrico). Se realizó un estudio comparativo del efecto citoprotector del DECC (10 mg/kg) con otras drogas citoprotectoras: cromoglicato disódico (10 mg/kg), cimetidina (2,5 mg/kg) y sus combinaciones. Se comparó el DECC con el citrato de sodio a dosis equimolares en este modelo de inducción de lesiones

Uso de plantas medicinales en dos municipios habaneros / Use of edicinal plants in two municipalities in Havana

Se realizó una encuesta en la población de Regla y Guanabacoa, Ciudad de La Habana, dirigida a los yerberos, curanderos o conocedores del uso de plantas con fines medicinales. Se entrevistaron 110 personas y se obtuvo información acerca de 104 plantas, las cuales fueron identificadas y clasificadas. Se investigó en cada planta las afecciones para que las que se utilizan, su modo de obtenciòn, las partes de las plantas empleadas y las vías de administraciòn. Se encontró que las afecciones tratadas corresponden a diversos aparatos y sistemas; las plantas se obtienen fundamentalmente mediante el cultivo en patios y jardines; las partes mas utilizadas son las hojas; la forma de preparación más frecuente es la decocción y la via de administración más usada es oral

Citoprotección gástrica por cromoglicato disódico y RS-7540 / Gastric cytoprotection by disodiu chromoglycate and RS-7540

Se estudió el efecto de la droga RS-7540 sobre la secreción gástrica en ratas sometidas a ligadura del piloro por una hora. Se comparó, con la utilización de dosis equimolares (2,0. 10 mol/kg) la acción del CGDS con li de la droga RS-7540 en el modelo de inducción de lesiones por etanol al 96

Se encontró que la droga RS-7540 no inhibió significativamente el volumen ni la acidez de la secreción gástrica y protegió la mucosa gástrica de las lesiones inducidas por etanol al 96

, por lo que tiene un efecto citoprotector. No existen diferencias significativas sobre el efecto citoprotector de la droga RS-7540 y del cromoglicato disódico. La administración simultánea de ambas drogas no aumenta la protección de la mucosa gástrica