Brain solute transport is more rapid in periarterial than perivenous spaces

Fluid flow in perivascular spaces is recognized as a key component underlying brain transport and clearance. An important open question is how and to what extent differences in vessel type or geometry affect perivascular fluid flow and transport. Using computational modelling in both idealized and image-based geometries, we study and compare fluid flow and solute transport in pial (surface) periarterial and perivenous spaces. Our findings demonstrate that differences in geometry between arterial and venous pial perivascular spaces (PVSs) lead to higher net CSF flow, more rapid tracer transport and earlier arrival times of injected tracers in periarterial spaces compared to perivenous spaces. These findings can explain the experimentally observed rapid appearance of tracers around arteries, and the delayed appearance around veins without the need of a circulation through the parenchyma, but rather by direct transport along the PVSs.

A Prevalent Focused Human Antibody Response to the Influenza Virus Hemagglutinin Head Interface

The rapid appearance of mutations in circulating human influenza viruses and selection for escape from herd immunity require prediction of likely variants for an annual updating of influenza vaccines. The identification of human antibodies that recognize conserved surfaces on the influenza virus hemagglutinin (HA) has prompted efforts to design immunogens that might selectively elicit such antibodies.

Functionalized Hydroperoxide Formation from the Reaction of Methacrolein-Oxide, an Isoprene-Derived Criegee Intermediate, with Formic Acid: Experiment and Theory

Methacrolein oxide (MACR-oxide) is a four-carbon, resonance-stabilized Criegee intermediate produced from isoprene ozonolysis, yet its reactivity is not well understood. This study identifies the functionalized hydroperoxide species, 1‑hydroperoxy-2-methylallyl formate (HPMAF), generated from the reaction of MACR-oxide with formic acid using multiplexed photoionization mass spectrometry (MPIMS, 298 K = 25 °C, 10 torr = 13.3 hPa). Electronic structure calculations indicate the reaction proceeds via an energetically favorable 1,4-addition mechanism. The formation of HPMAF is observed by the rapid appearance of a fragment ion at m/z 99, consistent with the proposed mechanism and characteristic loss of HO2 upon photoionization of functional hydroperoxides. The identification of HPMAF is confirmed by comparison of the appearance energy of the fragment ion with theoretical predictions of its photoionization threshold. The results are compared to analogous studies on the reaction of formic acid with methyl vinyl ketone oxide (MVK-oxide), the other four-carbon Criegee intermediate in isoprene ozonolysis.

Brain solute transport is more rapid in periarterial than perivenous spaces

Background: Perivascular fluid flow, of cerebrospinal or interstitial fluid in spaces surrounding brain blood vessels, is recognized as a key component underlying brain transport and clearance. An important open question is how and to what extent differences in vessel type or geometry affect perivascular fluid flow and transport. Methods: Using computational modelling in both idealized and image-based geometries, we study and compare fluid flow and solute transport in pial (surface) periarterial and perivenous spaces. Results: Our findings demonstrate that differences in geometry between arterial and venous pial perivascular spaces (PVSs) lead to higher net CSF flow, more rapid tracer transport and earlier arrival times of injected tracers in periarterial spaces compared to perivenous spaces. Conclusions: These findings can explain the experimentally observed rapid appearance of tracers around arteries, and the delayed appearance around veins without the need of a circulation through the parenchyma, but rather by direct transport along the PVSs.

Brain solute transport is more rapid in periarterial than perivenous spaces

Background: Perivascular fluid flow, of cerebrospinal or interstitial fluid in spaces surrounding brain blood vessels, is recognized as a key component underlying brain transport and clearance. An important open question is how and to what extent differences in vessel type or geometry affect perivascular fluid flow and transport. Methods: Using computational modelling in both idealized and image-based geometries, we study and compare fluid flow and solute transport in pial (surface) periarterial and perivenous spaces. Results: Our findings demonstrate that differences in geometry between arterial and venous pial perivascular spaces (PVSs) lead to higher net CSF flow, more rapid tracer transport and earlier arrival times of injected tracers in periarterial spaces compared to perivenous spaces. Conclusions: These findings can explain the experimentally observed rapid appearance of tracers around arteries, and the delayed appearance around veins without the need of a circulation through the parenchyma, but rather by direct transport along the PVSs.

Is COVID-19 infection triggering oral herpes zoster? A case report

Patients affected with COVID-19 are at risk of developing serious and life-threatening conditions. The clinical manifestations of COVID-19 were detected in asymptomatic cases to severe clinical symptoms with a major impact on the respiratory system. A few cases of cutaneous as well as an oral lesion of herpes zoster in patients with COVID-19 were reported in the literature. We present a case of the rapid appearance of the oral lesion as a manifestation of herpes zoster associated with COVID-19 infection. Our case highlights the importance of oral examination as well as oral care in patients with COVID-19 infection.

Risperidone-Induced Erythema Multiforme Minor: A Case Report

Erythema Multiforme (EM) is a hypersensitivity reaction that can be triggered by an infection or particular medications. Erythema multiforme minor (EM minor) represents localized skin lesions with minimal or no mucosal involvement. Only a few case of EM associated with risperidone are found in the scientific literature. In this case report, the administration of the risperidone resulted in the rapid appearance of skin lesions. Erythematous lesions were recovered upon discontinuation of the drug and no new skin lesion was observed. A 52-year-old male patient was admitted to the psychiatry hospital because of developing schizophrenic symptoms. At the time of admission, risperidone was added to her previous drug regimen. Two weeks later, the patient returned with a complaint of progressively increasing rashes over his body. The patient was diagnosed with EM minor. The prescribed risperidone was discontinued due to its side-effect profile and the patient’s drug regimen was changed entirely to the olanzapine, haloperidol, and topical clobetasol. At one month follow up visit, his skin lesions were satisfactorily controlled.

General regularities in the development Gzhelian-Asselian conodonts

Subject of study. The features of the evolutionary changing of Gzhelian-Asselian conodonts are examined. Materials. The data on Ural and North American conodonts are used. Results. The cyclic type of change of the Pa-element morphology in the process of the evolutionary development of the representatives of the genus Streptognathodus is established. Morphological evolutionary trends of gradual development alternate with the periods of the rapid appearance of a group of the forms of original constitution. The species of this group are characterized by wide distribution and short lifetime. Such species are used as the markers of the boundaries of stratigraphic subdivisions. Lower boundary of Gzhelian is determined by the appearance of species of the group simulator; the species of group isolatus mark lower boundary of Asselian. Model of the ensemble evolution of the related species is used for explaining the directed change in the morphology of conodonts. The saltational appearance of the determined indication is explained by the phenomenon of evolutionary oscillations. Conclusion. We can make conclusion about the sexual multiplication of this group of the organisms according the established alternation of the periods of the slow and rapid morphological evolution of conodonts.

Expression of the neuropeptide SALMFamide-1 during regeneration of the seastar radial nerve cord following arm autotomy

Arm loss through a separation at a specialized autotomy plane in echinoderms is inextricably linked to regeneration, but the link between these phenomena is poorly explored. We investigated nervous system regeneration post-autotomy in the asteriid seastar Coscinasterias muricata , focusing on the reorganization of the radial nerve cord (RNC) into the ectoneural neuroepithelium and neuropile, and the hyponeural region, using antibodies to the seastar-specific neuropeptide SALMFamide-1 (S1). Parallel changes in the associated haemal and coelomic vessels were also examined. A new arm bud appeared in 3–5 days with regeneration over three weeks. At the nerve stump and in the RNC immediately behind, the haemal sinus/hyponeural coelomic compartments enlarged into a hypertrophied space filled with migratory cells that appear to be involved in wound healing and regeneration. The haemal and coelomic compartments provided a conduit for these cells to gain rapid access to the regeneration site. An increase in the number of glia-like cells indicates the importance of these cells in regeneration. Proximal to the autotomy plane, the original RNC exhibited Wallerian-type degeneration, as seen in disorganized axons and enlarged S1-positive varicosities. The imperative to regrow lost arms quickly is reflected in the efficiency of regeneration from the autotomy plane facilitated by the rapid appearance of progenitor-like migratory cells. In parallel to its specialization for defensive arm detachment, the autotomy plane appears to be adapted to promote regeneration. This highlights the importance of examining autotomy-induced regeneration in seastars as a model system to study nervous system regeneration in deuterostomes and the mechanisms involved with the massive migration of stem-like cells to facilitate rapid recovery.

Physical and mechanical studies on binary blended Portland cements containing mordenite-rich tuff and limestone filler

In this research, we made physical and mechanical analyses thanks to which we deduced that the potential of replacing the Portland cement up to 20% by modernite-rich tuff (TM) and limestone filler (LF). The experimental procedure was done in two main stages. The first stage was dedicated to the pastes, including water requirement, setting time, hydration heat and free Ca(OH)2 content. In the second stage, mechanical and physical properties of mortars, water porosity and pore size distribution were studied. The final results show that LF mixtures closest to the control mixtures unlike the MT mixtures which exhibited a high water demand, less free Ca(OH)2, rapid appearance of the maximum thermal effect, an increase in the total and water accessible porosity, there is also a delay in improving of strength.