Pharmacological protection of vascular endothelium in acute COVID-19.

Since the beginning of the COVID-19 pandemic, there has been an urgent need to find effective treatment. It is widely known that virus attacks and damages mostly the lungs, but also infect vascular endothelial cells. Therefore, the protection of the endothelium is a promising target in the therapy of COVID-19 and its complications. In this review article, we focused on several groups of drugs with potential to protect the endothelium. The most promising ones are angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, drugs targeting angiotensin-converting enzyme 2, heparins, sulodexide, acetylsalicylic acid, statins, tocilizumab, baricitinib, and defibrotide. Although the short period of trials and the lack of data necessitate further research, endothelial protection remains a promising target for COVID-19 therapy.

Highly organized nanostructures for brain drug delivery--new hope or just a fad?

The blood-brain barrier significantly impedes treatment of central nervous system disorders by preventing drug entry into the brain. Several strategies have been developed to overcome this problem, but progress has been hampered due to a lack of efficacious drug delivery systems (DDS). Now, owing to DDS, therapeutic compounds can be transported to the site of action and accumulate there. This modern approach allows one to decrease the required dose of drug and, therefore, minimize toxicity and side effects. Also, treatment efficiency is increased. Highly organized nanostructures made of biological, polymeric or carbon-based materials are promising carriers in drug delivery to the brain, due to their unique and easily tailorable properties. The drug can be either attached to or entrapped in a carrier. To achieve greater site specificity and selectivity, DDS can be also modified with suitable ligands, providing identification of the molecular site of action. This review illustrates recent advances in using highly-organized structures: dendrimers, fullerenes, liposomes, micelles, nanogels, nanoparticles and nanotubes for this purpose. We also discuss advantages and limitations of each system.

Limbal stem cells transplantation in the reconstruction of the ocular surface: 6 years experience.

PURPOSE: To analyze the graft survival rate and stability of the corneal surface in patients who underwent limbal stem cell transplantation. Three surgical techniques were performed based on the origin of the ocular surface lesion: conjunctival limbal autograft (CLAU), living-related conjunctival limbal autograft (lr-CLAL), and keratolimbal allograft (KLAL) transplantations. METHODS: Nonrandomized consecutive comparative case series study. Eighty-four patients (90 eyes; 31 women and 53 men; age range: 11-78 years) were included in the study. Mean follow-up was 31.2 months (range: 6-72 months). Patients were divided into three groups: CLAU, lr-CLAL, and KLAL, comprising 21, 26, and 43 eyes, respectively. Graft survival rate and clinical success of the stem cell transplantation was confirmed by impression cytology. The Kaplan Meier survival curve and generalized Peto tests were used for the analyses. RESULTS: Graft survival rate and the regularity of the corneal surface differed significantly between the allo- and autografts. The 3-year and 6-year graft survival rates were 76.1% and 61.9%, respectively, for the autologous transplantation group, and 59.4% and 46.3%, respectively, for the allogeneic transplantation group. Corneal surface restoration correlated with positive staining for corneal epithelial cells in impression cytology. CONCLUSIONS: Significantly better long-term outcomes were achieved with autotransplantation of the limbus compared with allogeneic limbal grafts from living-related and cadaveric donors.

Does trimetazidine exert cytoprotective activity on astrocytes subjected to hypoxia in vitro?

The aim of the present study was to establish whether trimetazidine (TMZ) is capable of protecting astrocytes against hypoxic injury. Using the model of astrocyte cell culture we tried to observe the cells treated with TMZ before, during and after hypoxia simulated in vitro. Cell viability was determined by Live/Dead (viability/cytotoxicity) Assay Kit and MTT conversion test. Apoptotic cell death was distinguished by a method using fluorescence microscopy with Hoechst 33342. The effect of the drug on the DNA synthesis was evaluated by measuring the incorporation of [3H]thymidine into DNA of astrocytes. TMZ stimulates the proliferation of astrocytes most significant one when the astrocytes are exposed to the drug in normoxia, hypoxia and/or re-oxygenation. Adding TMZ into cultures during re-oxygenation and hypoxial re-oxygenation significantly decreases the number of dead and apoptotic cells. Our experiment has proved that TMZ exerts the most significantly cytoprotective effect on astrocytes in vitro when added during hypoxia and/or re-oxygenation. We may conclude that the protective effect of TMZ depends on the sequence of drug adding and hypoxia/ re-oxygenation onset.

Role of astrocytes in pathogenesis of ischemic brain injury.

Astrocytes play an important role in the homeostasis of the CNS both in normal conditions and after ischemic injury. The swelling of astrocytes is observed during and several seconds after brain ischemia. Then ischemia stimulates sequential morphological and biochemical changes in glia and induces its proliferation. Reactive astrocytes demonstrate stellate morphology, increased glial fibrillary acidic protein (GFAP) immunoreactivity, increased number of mitochondria as well as elevated enzymatic and non-enzymatic antioxidant activities. Astrocytes can re-uptake and metabolize glutamate and in this way they control its extracellular concentration. The ability of astrocytes to protect neurons against the toxic action of free radicals depends on their specific energy metabolism, high glutathione level, increased antioxidant enzyme activity (catalase, superoxide dismutase, glutathione peroxidase) and overexpression of antiapoptotic bcl-2 gene. Astrocytes produce cytokines (TNF-alpha, IL-1, IL-6) involved in the initiation and maintaining of immunological response in the CNS. In astrocytes, like in neurones, ischemia induces the expression of immediate early genes: c-fos, c-jun, fos B, jun B, jun D, Krox-24, NGFI-B and others. The protein products of these genes modulate the expression of different proteins, both destructive ones and those involved in the neuroprotective processes.

Effect of nebracetam on content of high-energy phosphates and morphometry of rat astrocytes in vitro. Comparison with piracetam.

The present study was initiated to examine the effect of nebracetam, a nootropic drug, on various biochemical and morphometric parameters in order to gain some insight into the mechanism of this agent action. The content of adenosine triphosphate (ATP) and phosphocreatine (PCr) and 3H-valine incorporation into proteins was measured and the morphometry was performed after nebracetam and piracetam treatment of rat astrocytes cultured in vitro with or without dibutyryl 3',5'-cyclic adenosine monophosphate (dBcAMP). Nootropics were added into the culture medium for 2 weeks at the final concentration of 10(-7) M. Cultured astrocytes treated with either nebracetam or piracetam showed decreased intracellular ATP and PCr levels. The addition of nebracetam and dBcAMP to cultures caused an increase of PCr content in astrocytes. The astrocytes treated with nebracetam showed a decrease in 3H-valine incorporation. The increase of 3H-valine incorporation into astrocytes after piracetam with dBcAMP treatment was found. Nootropic drugs change morphometric parameters (cell area, perimeter and form factor) of cultured astrocytes. It can be concluded that nootropics have differentiated influence on both the energetic metabolism and morphology of rat astrocytes in vitro.

Influence of piracetam and oxiracetam on the content of high-energy phosphates and morphometry of astrocytes in vitro.

The nootropic drugs, including piracetam (PIR) and oxiracetam (OXI) are used in the adjunctive treatment of dementia. They are thought to directly influence energetic processes in the brain and, therefore, they are supposed to improve memory and cognition. The content of adenosine triphosphate (ATP) and phosphocreatine (PCr) and 3H-valine incorporation into proteins were measured, and the morphometry was performed after PIR and OXI treatment of astrocytes cultured in vitro with or without dibutyryl 3',5'-cyclic adenosine monophosphate (dBcAMP). Nootropics were added into the culture medium for 2 weeks at a final concentration of 10(-7) M. It was shown that OXI increased ATP content in astrocytes cultured with or without dBcAMP. The increase in 3H-valine incorporation into astrocytes after PIR and OXI together with dBcAMP treatment was found. These results indicate that the presented research model allows to study energetic processes in cultured astrocytes. However, nootropic drugs changed morphometric parameters (cell area, perimeter and form factor) of cultured astrocytes as well. It can be concluded that PIR and OXI as nootropics have an opposing effect on the content of high-energy phosphates and shape of astrocytes in vitro.

Leucine enkephalin level in rat hypothalamus, striatum, hippocampus and adrenal glands in experimental rat uremia.

The aim of the study was to analyze the effect of experimental uremia elicited in Wistar rats by 5/6 kidney resection on the leu-enkephalin level in hypothalamus, striatum, hippocampus and adrenal glands. We found, that in uremic rats leu-enkephalin levels decreased in striatum and in adrenal glands. The level of leu-enkephalin in adrenal glands was directly related to plasma creatinine. The weight of uremic rats was significantly lower than that of control rats.

Effect of captopril and thiorphan on the proliferation of human neoplastic cell lines and their influence on cytostatic activity of interferon alpha or cytotoxic activity of doxorubicin.

We have assessed the effect of thiorphan or captopril on proliferation of two human tumor cell lines, A549 and HL60 including their influence on the cytostatic activity of interferon alpha or doxorubicin. The results showed that captopril inhibits the proliferation of both A549 and HL60 cells lines but thiorphan has antiproliferative effect only on A549 cells in a dose-dependent manner. However, neither captopril nor thiorphan administered in combination with interferon alpha or doxorubicin enhanced cytotoxic potential of doxorubicin and cytostatic activity of interferon alpha.

Effect of antidepressants on ATP content, 3H-valine incorporation and cell morphometry of astrocytes cultured from rat brain.

ATP is a potential marker of cell vialibility and growth. The content of ATP and 3H-valine incorporation into proteins were measured and the morphometry was performed after antidepressant treatment of astrocytes cultured in vitro with or without dibutyryl 3'5'-cyclic adenosine monophosphate (dB-cAMP). Antidepressants were added into the culture medium (for 24 h) at a final concentration of 10(-4)M (imipramine, amitriptyline, clomipramine, doxepine, mianserin) or 10(-5)M (maprotiline). It was shown that all antidepressants except maprotiline and imipramine increased ATP level and decreased 3H-valine incorporation into astrocytes. All drugs except clomipramine and maprotiline, diminished cell area and perimeter of astrocytes. The addition of dB-cAMP to cultures caused an increase of astrocyte form factor. It can be concluded that antidepressants have a significant effect on energy metabolism and differentiation of astrocytes cultured in vitro.

Nootropics: pharmacological properties and therapeutic use.

This review summarizes the results of studies investigating the pharmacological properties, mechanisms of action, preclinical and clinical effects of nootropic drugs, and tries to integrate this knowledge in order to identify neuronal mechanisms underlying their therapeutic benefits and side effects.