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Ruben Lerma laughs as Dr. Hector P. Garcia lifts his fist and Colonel Charles F. Drenz laughs along (photograph)
No full text(L. to R.): Ruben Lerma laughs as Dr. Hector P. Garcia lifts his fist and Colonel Charles F. Drentz laughs along
Covid-19 in Chronic Kidney Disease: The Impact of Old and Novel Cardiovascular Risk Factors
No full textCardiovascular disease is a frequent complication and the most common cause of death in patients with CKD. Despite landmark medical advancements, mortality due to cardiovascular disease is still 20 times higher in CKD patients than in the general population, which is mainly due to the high prevalence of risk factors in this group. Indeed, in addition to traditional cardiovascular risk factors, CKD patients are exposed to nontraditional ones, which include metabolic, hormonal, and inflammatory alterations. The global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has brought novel challenges for both cardiologists and nephrologists alike. Emerging evidence indicates that coronavirus disease 2019 (COVID-19) increases the risk of cardiovascular events and that several aspects of the disease may synergize with pre-existing cardiovascular risk factors in CKD patients. A better understanding of these mechanisms is pivotal for the prevention and treatment of cardiovascular events in this context, and we believe that additional clinical and experimental studies are needed to improve cardiovascular outcomes in CKD patients with COVID-19. In this review, we provide a summary of traditional and nontraditional cardiovascular risk factors in CKD patients, discussing their interaction with SARS-CoV-2 infection and focusing on CO-VID-19-related cardiovascular complications that may severely affect short- and long-term outcomes in this high-risk population
Non-ohmic behavior and resistive switching of Au cluster-assembled films beyond the percolation threshold
No full textNetworks based on nanoscale resistive switching junctions are considered promising for the fabrication of neuromorphic computing architectures. To date random networks of nanowires, nanoparticles, and metal clusters embedded in a polymeric matrix or passivated by shell of ligands or oxide layers have been used to produce resistive switching systems. The strategies applied to tailor resistive switching behavior are currently based on the careful control of the volume fraction of the nanoscale conducting phase that must be fixed close to the electrical percolation threshold. Here, by blending laboratory and computer experiments, we demonstrate that metallic nanostructured Au films fabricated by bare gold nanoparticles produced in the gas phase and with thickness well beyond the electrical percolation threshold, show a non-ohmic electrical behavior and complex and reproducible resistive switching. We observe that the nanogranular structure of the Au films does not evolve with thickness: this introduces a huge number of defects and junctions affecting the electrical transport and causing a dynamic evolution of the nanoscale electrical contacts under the current flow. To uncover the origin of the resistive switching behavior in Au cluster-assembled films, we developed a simple computational model for determining the evolution of a model granular film under bias conditions. The model exploits the information provided by experimental investigation about the nanoscale granular morphology of real films. Our results show that metallic nanogranular materials have functional properties radically different from their bulk counterparts, in particular nanostructured Au films can be fabricated by assembling bare gold clusters which retain their individuality to produce an all-metal resistive switching system
Current therapy in ckd patients can affect vitamin k status
No full textChronic kidney disease (CKD) patients have a higher risk of cardiovascular (CVD) morbidity and mortality compared to the general population. The links between CKD and CVD are not fully elucidated but encompass both traditional and uremic-related risk factors. The term CKD-mineral and bone disorder (CKD-MBD) indicates a systemic disorder characterized by abnormal levels of calcium, phosphate, PTH and FGF-23, along with vitamin D deficiency, decreased bone mineral density or altered bone turnover and vascular calcification. A growing body of evidence shows that CKD patients can be affected by subclinical vitamin K deficiency; this has led to identifying such a condition as a potential therapeutic target given the specific role of Vitamin K in metabolism of several proteins involved in bone and vascular health. In other words, we can hypothesize that vitamin K deficiency is the common pathogenetic link between impaired bone mineralization and vascular calcification. However, some of the most common approaches to CKD, such as (1) low vitamin K intake due to nutritional restrictions, (2) warfarin treatment, (3) VDRA and calcimimetics, and (4) phosphate binders, may instead have the opposite effects on vitamin K metabolism and storage in CKD patients
Weight distribution of cyclic codes defined by quadratic forms and related curves
No full textWe consider cyclic codes CL associated to quadratic trace forms inm variables (Formula Presented) determined by a family L of q-linearized polynomials R over Fqm, and three related codes CL,0, CL,1, and CL,2. We describe the spectra for all these codes when L is an even rank family, in terms of the distribution of ranks of the forms QR in the family L, and we also computethe complete weight enumerator for CL. In particular, considering the family L = ‹xql›, with l fixed in N, we give the weight distribution of four parametrized families of cyclic codes Cl, Cl,0,Cl,1, and Cl,2 over Fq with zeros(Formula Presented) respectively,where q = ps with p prime, α is a generator of F*qm, and m/(m,l)is even. Finally, we give simple necessary and sufficient conditions for Artin–Schreier curves yp−y = xR(x)+βx, p prime, associated to polynomials R ∈ L to be optimal. We then obtain several maximal and minimal such curves inthe case (Formula Presented).Fil: Podesta, Ricardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Estudios de Matemática. Universidad Nacional de Córdoba. Centro de Investigación y Estudios de Matemática; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Videla Guzman, Denis Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Estudios de Matemática. Universidad Nacional de Córdoba. Centro de Investigación y Estudios de Matemática; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin
Increased expression of tissue type plasminogen activator, and its inhibitor and reduced fibrinolytic potential of human endothelial cells cultured in elevated glucose
No full textIn diabetic patients, elevated plasma levels of t-PA and PAI-1 accompany impaired fibrinolysis. To identify mechanisms for these abnormalities, we examined whether vascular endothelial cells exposed to high glucose upregulate t-PA and PAI-1 production and whether ambient PA activity is decreased concomitantly. In 17 cultures of human umbilical vein endothelial cells grown to confluency in 30 mM glucose, the t-PA antigen released to the medium in 24 h was (median) 52 ng/106 cells (range 10-384) and the PAI-1 antigen was 872 ng/106 cells (range 217-2074)-both greater (P < 0.02) than the amounts released by paired control cultures grown in 5 mM glucose-29 ng/106 cells (range 7.5-216) and 461 ng/106 cells (range 230-3215), respectively. In the presence of high glucose, the steady-state levels of t- PA and PAI-1 mRNAs were increased correspondingly (median 142 and 183% of control, respectively, P < 0.05); high glucose per se and hypertonicity contributed to the upregulation in additive fashion. The PA activity of conditioned medium from cultures exposed to high glucose was 0.4 IU/ml (range 0.2-0.6), which was significantly lower (P < 0.02) than the PA activity of control medium (0.5 IU/ml, range 0.2-0.9). No difference was observed when comparing the PA activities of acidified conditioned media, expected to be depleted of inhibitors. Thus, high glucose coordinately upregulates endothelial t-PA and PAI-1 expression through effects exerted at the pretranslational level and enhanced by even mild degrees of hypertonicity. The decrease in ambient fibrinolytic potential may reflect an overwhelming effect of the increased availability of PAI-1. These findings propose a contributory mechanism for the fibrinolytic abnormalities of diabetes and the thrombotic tendency of the hyperglycemic hyperosmolar state
Induction and survival of binucleated Purkinje neurons by selective damage and aging.
No full textFusion of bone marrow-derived cells with adult Purkinje cells in the cerebellum gives rise to binucleated Purkinje cells. Whether fusion
can be modulated by epigenetic factors and whether fused neurons are stable has remained unclear. Here, we show that in mice and rats,
partial ablation of Purkinje cells and local microglial activation in the absence of structural damage to the cerebellum increase the rate of
fusion. Moreover, mouse Purkinje cells once fused with bone marrow-derived cells are viable for at least 7 months. We also show that
cerebellar irradiation is unnecessary for the generation of binucleated Purkinje cells after bone marrow grafting. Moreover, binucleated
Purkinje cells can be found in aged mice that did not receive any treatment, suggesting that fusion events occasionally occur throughout
the whole lifespan of healthy, unmanipulated individuals. However, in aged chimeric mice that, after bone marrow transplant, have the
majority of their nucleated blood cells fluorescent, the number of binucleated fluorescent Purkinje cells is two orders of magnitude less
than the total number of binucleated Purkinje cells. This suggests that, in the majority of heterokaryons, either the incoming nucleus is
quickly inactivated or fusion is not the only way to generate a binucleated Purkinje cell
nanofriction behavior of cluster-assembled carbon films
No full textWe have characterized the frictional properties of nanostructured carbon films grown by supersonic cluster beam deposition via an atomic force-friction force microscope (AFM-FFM). The experimental data are discussed on the basis of a modified Amonton's law for friction, stating a linear dependence of friction on load plus an adhesive offset accounting for a finite friction force in the limit of null total applied load. Molecular dynamics simulations of the interaction of the AFM tip with the nanostructured carbon confirm the validity of the friction model used for this system. Experimental results show that the friction coefficient is not influenced by the nanostructure of the films nor by the relative humidity. On the other hand the adhesion coefficient depends on these parameters
Biology of visceral leishmaniasis vectors in San Andres de Sotavento focus (Cordoba Colombia).
No full textThroughout its range of South and
Central America,
visceral
leishmaniasis due to
Leishmania chagasi is transmitted by Lutzomyia longipalpis.
Recently,
a new
vector,
Lutzomyia
evansi, has been discovered transmitting the
parasite
in the
Caribbean Coast
of
Colombia.
Field studies, using both experimental and
observational
methodologies
were employed
to elucidate the main ecological and
behavioural factors
affecting
disease transmission in the
focus of San Andres de Sotavento, northern
Colombia.
Nine
species
of Lutzomyia were present
and Lu. evansi constituted 90% of all sandflies
caught.
Flies
were most
abundant
in
April, May
June and September. Trapping in and around
houses
showed
Lu.
evansi to
be
endophilic
but
with exophagic behaviour, preferring
houses
near to forest
edge
as resting places.
Host preference, measured using a newly
designed trap
in
a rotational
experimental
design, showed that humans were preferred over
dogs
or opossums
(reservoirs)
during the
peak
abundance of Lu. evansi. This was supported
by
catches
on tethered
hosts
and
bloodmeal
analysis although location of capture of
resting
flies
was also a significant
factor.
Mark-release-recapture studies showed that
Lu. evansi can move
up to
800m
after
5
days and that freshly fed flies move a
few hundred
metres to
resting sites.
Basic life history data on Lu. evansi
was obtained
from laboratory
rearing.
This
species
was bred under laboratory conditions though
high
mortalities
were
seen
in first instars. In
adults
survival was associated with different types
of sugar.
Flagellate parasites resembling
L.
chagasi were
found in
3
of
5326
wild
caught
Lu.
evansi (0.05%) however, culturing and
subsequent
characterization
of these
isolates failed.
Experimental infections with L. chagasi showed that
at
least
one strain of the
parasite
grew
more prolifically in Lu. longipalpis than in
Lu.
evansi.
This, together
with a
limited
vector
range
compared to the Old World L. infantum is
suggested to
be the
result of a recent
parasite-vector
association.
Morphologically no differences were
seen
between
Colombian,
Venezuelan
and
Costa
Rican Lu. evansi populations. Some variation
was seen
however in
one enzyme
(6GPDH)
of
18
isozymes tested. Mitochondrial DNA variation
was seen
between
Central
and
South American
populations
Actigraphic Sensors Describe Stroke Severity in the Acute Phase: Implementing Multi-Parametric Monitoring in Stroke Unit
No full textActigraphy is a tool used to describe limb motor activity. Some actigraphic parameters, namely Motor Activity (MA) and Asymmetry Index (AR), correlate with stroke severity. However, a long-lasting actigraphic monitoring was never performed previously. We hypothesized that MA and AR can describe different clinical conditions during the evolution of the acute phase of stroke. We conducted a multicenter study and enrolled 69 stroke patients. NIHSS was assessed every hour and upper limbs’ motor activity was continuously recorded. We calculated MA and AR in the first hour after admission, after a significant clinical change (NIHSS ± 4) or at discharge. In a control group of 17 subjects, we calculated MA and AR normative values. We defined the best model to predict clinical status with multiple linear regression and identified actigraphic cut-off values to discriminate minor from major stroke (NIHSS ≥ 5) and NIHSS 5–9 from NIHSS ≥ 10. The AR cut-off value to discriminate between minor and major stroke (namely NIHSS ≥ 5) is 27% (sensitivity = 83%, specificity = 76% (AUC 0.86 p < 0.001), PPV = 89%, NPV = 42%). However, the combination of AR and MA of the non-paretic arm is the best model to predict NIHSS score (R2: 0.482, F: 54.13), discriminating minor from major stroke (sensitivity = 89%, specificity = 82%, PPV = 92%, NPV = 75%). The AR cut-off value of 53% identifies very severe stroke patients (NIHSS ≥ 10) (sensitivity = 82%, specificity = 74% (AUC 0.86 p < 0.001), PPV = 73%, NPV = 82%). Actigraphic parameters can reliably describe the overall severity of stroke patients with motor symptoms, supporting the addition of a wearable actigraphic system to the multi-parametric monitoring in stroke units
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