Age‐related cognitive failure is a main devastating incident affecting even healthy people. Alzheimer's disease (AD) is the utmost common form of dementia among the geriatric community. In the pathogenesis of AD, cerebrovascular dysfunction is revealed before the beginning of the cognitive decline. Mounting proof shows a precarious impact of cerebrovascular dysregulation in the development of AD pathology. Recent studies document that the mammalian target of rapamycin (mTOR) acts as a crucial effector of cerebrovascular dysregulation in AD. The mTOR contributes to brain vascular dysfunction and subsequence cerebral blood flow deficits as well as cognitive impairment. Furthermore, mTOR causes the blood–brain barrier (BBB) breakdown in AD models. Inhibition of mTOR hyperactivity protects the BBB integrity in AD. Furthermore, mTOR drives cognitive defect and cerebrovascular dysfunction, which are greatly prevalent in AD, but the central molecular mechanisms underlying these alterations are obscure. This review represents the crucial and current research findings regarding the role of mTOR signaling in cognitive aging and cerebrovascular dysfunction in the pathogenesis of AD.

Introduction : Global emergence of coronavirus disease-19 (COVID-19) has clearly shown variable severity, mortality, and frequency between and within populations worldwide. These striking differences have made many biological variables attractive for future investigations. One of these variables, vitamin D, has been implicated in COVID-19 with rapidly growing scientific evidence. Areas covered : The review intended to systematically explore the sources, and immunomodulatory role of vitamin D in COVID-19. Search engines and data sources including Google Scholar, PubMed, NCBI, Scopus, and Web of Science were used for data collection. The search terms used were Vitamin D, COVID-19, immune system, and antiviral mechanism. Overall, 232 sources of information were collected and 188 were included in this review. Expert opinion : Interaction of vitamin D and vitamin D receptor (VDR) triggers the cellular events to modulate the immune system by regulation of many genes. Vitamin D operates as a double-edged sword against COVID-19. First, in macrophages, it promotes the production of antimicrobial and antiviral proteins like β-defensin 2 and cathelicidin, and these proteins inhibit the replication of viral particles and promote the clearance of virus from the cells by autophagy. Second, it suppresses cytokine storm and inflammatory processes in COVID-19.

We evaluated the effect of prebiotic or probiotic as feed additives on florfenicol kinetic in broilers feed. Unsexed two hundred, thirty‐five‐day‐old broiler chickens, were put in four equal groups (n = 50). The first group was administrated florfenicol intravenous at 30 mg/kg body weight (BW) only once dosage without pre‐ or probiotic administration to determine the bioavailability. While, the second group was administrated florfenicol (intracrop routes; a dosage of 30 mg/kg BW for five progressive days) without pre‐ or probiotic co‐administration. The third and the fourth groups were administrated the same dose of florfenicol (intracrop route) for five successive days, followed by 10 days of prebiotic or probiotic treatment respectively. The plasma florfenicol % was identified by high‐pressure liquid chromatography (HPLC) after the first florfenicol administration (intravenous or intracrop routes) in all groups. Then, the residual levels of florfenicol were determined in liver, kidney and muscle tissues from the second, third and fourth groups which were exposed to florfenicol orally. Our results demonstrated that broilers pre‐treated with prebiotic or probiotic significantly increased Cmax, AUC0–t, AUC0–inf as well as AUMC values, while significant drop was recorded in V/F and CL/F. Prebiotic or probiotic influenced the cumulative effect of florfenicol in liver and kidney tissues of treated birds.

A solid state sensor tool used for determination of ferric ions (Fe+3) in an aqueous medium was developed using the environmental friendly tannin polyphenolic biomolecule as spectroscopic probe and silica plates as a host strip. The colorimetric recognition of the analyte is based on a tanna‐activated silica dipstick with a determination limit in the ppm level. The best detection of Fe (III) was accomplished in a pH range from 3.2 to 8.8. The metallochromic tannin‐impregnated silica diagnostic tool provided an instant color alteration from yellow to dark purple upon immersion in an aqueous environment of ferric cation as was demonstrated by the coloration measurements. This color shift is proportionally correlated with increasing the ferric concentration. Both qualitative and quantitative studies were performed. The sensor demonstrated high selectivity to Fe (III), while no color change was monitored for other metals. The recognition mechanism of ferric occurs via tannic (polyphenolic)‐Fe (III) polydentate complex creation. Different spectroscopic techniques, including scanning electron microscope, energy dispersive X‐ray spectroscopy as well as elemental mapping were utilized to characterize the tannic‐Fe (III) complex formation on the silica dipstick.

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