Nanomedicine for acute respiratory distress syndrome: The latest application,targeting strategy,and rational design

Acute respiratory distress syndrome (ARDS) is characterized by the severe inflammation and destruction of the lung air–blood barrier, leading to irreversible and substantial respiratory function damage. Patients with coronavirus disease 2019 (COVID-19) have been encountered with a high risk of ARDS, underscoring the urgency for exploiting effective therapy. However, proper medications for ARDS are still lacking due to poor pharmacokinetics, non-specific side effects, inability to surmount pulmonary barrier, and inadequate management of heterogeneity. The increased lung permeability in the pathological environment of ARDS may contribute to nanoparticle-mediated passive targeting delivery. Nanomedicine has demonstrated unique advantages in solving the dilemma of ARDS drug therapy, which can address the shortcomings and limitations of traditional anti-inflammatory or antioxidant drug treatment. Through passive, active, or physicochemical targeting, nanocarriers can interact with lung epithelium/endothelium and inflammatory cells to reverse abnormal changes and restore homeostasis of the pulmonary environment, thereby showing good therapeutic activity and reduced toxicity. This article reviews the latest applications of nanomedicine in pre-clinical ARDS therapy, highlights the strategies for targeted treatment of lung inflammation, presents the innovative drug delivery systems, and provides inspiration for strengthening the therapeutic effect of nanomedicine-based treatment.     

The Catalytic Mechanism of Angiotensin Converting Enzyme

A detailed investigation of the catalytic mechanism of angiotensin converting enzyme was undertaken in order to establish a molecular basis for its mode of action. These studies include the characterization of the kinetic properties of the enzyme. In particular, a mechanism for the anion activation, a characteristic feature of angiotensin converting enzyme, has been established. The active site of the enzyme contains a catalytically essential zinc atom which appears to be directly involved in the hydrolytic step of catalysis. Further components of the active site are the carboxyl group of an aspartyl or glutamyl residue, tyrosyl, arginyl and lysyl residues. The latter one is involved in mediating the anion activation. These results have enabled us to compare the active site of angiotensin converting enzyme with those of two other zinc peptidases and, thereby, deduce a mechanism for its mode of action. These investigations have confirmed a hypothetical model of the active site of angiotensin converting enzyme which has served to construct potent inhibitors of the enzyme now being used as anti-hypertensive agents.     

Complémentation ou supplémentation en oligo-éléments : qui,pourquoi, comment ?

Trace elements (TE) are essential for biological and physiological functions. They come from food or artificial nutrition. Maintaining or restoring an optimal status is an objective that participates in the nutritional prevention of chronic pathologies. In the hospitalized patient, detecting and fighting deficits will promote faster recovery and reduce infectious complications. In the case of deficient dietary intakes which cannot be corrected by the one nutrition or artificial feeding, the use of suitable trace element supplements is essential. This review presents the main causes and consequences of trace element deficiencies in the general population and in hospital patient, as well as the biological and clinical markers of these deficits. It provides, on the basis of the current recommendations, a practical overview of the conditions for complementation or repletion by oral, enteral or parenteral route, avoiding toxicity with proposals for diagnostic methods and therapeutic interventions.     

Antiangiogenic evaluation of ZnWO4 nanoparticles synthesised through microwave-assisted hydrothermal method

Angiogenesis, the complex process of formation of new blood vessels from pre-existing blood vessels, which involves the participation of several pro- and anti-angiogenic factors, is implicated in many physiological and pathological conditions. Nanoparticle-based anti-angiogenic activity at the tumour tissue, harnessed by the Enhanced Permeability and Retention Effect (EPR effect), could potentially become a breakthrough therapy to halt tumour progression. Herein, we evaluate the anti-angiogenic effect of ZnWO₄ nanoparticles (NPs). The nanoparticles were obtained by microwave-assisted hydrothermal synthesis (MAHS) at 120?°C for 60?min and were structurally characterised by X-ray diffraction (XRD) and micro-Raman (MR) spectroscopy. The mean size and polydispersity index were estimated by Zeta potential analysis. The XRD analysis revealed structural organisation at a long-range order, with an average crystallite size of around 3.67?nm, while MR revealed short-range order for ZnWO₄. The anti-angiogenic potential of zinc tungstate nanoparticles was investigated through the chorioallantoic membrane assay (CAM) using fertilised chicken eggs. We demonstrate, in an unprecedented way, that nanocrystalline ZnWO₄ NPs obtained by MAHS, at low reaction temperatures, showed excellent anti-angiogenic properties even at low concentrations. The ZnWO₄ NPs were further evaluated for its cytotoxicity in vitro.     

Current treatment for primary ciliary dyskinesia conditions

Primary ciliary dyskinesia (PCD) is a heterogeneous group of conditions characterised by ultrastructural defects of the cilia, which result in impaired mucociliary clearance. Although the incidence of PCD is low, early recognition and prompt management are important in order to prevent unnecessary morbidity, the progression of bronchiectasis and the deterioration of lung function. As the underlying defect in PCD cannot be corrected, the mainstay of therapy remains effective clearance of airway secretions and antibiotic therapy of respiratory tract infections. This paper highlights new developments in the field that have implications for the future management of PCD. These include β-adrenergic agonists, arginine, uridine-5’-triphosphate, hypertonic saline and recombinant human DNase. It is to be hoped that these treatment modalities will have a therapeutic role in PCD.     

Efficacy of Oral Zinc Sulfate Supplementation on Clearance of Cervical Human Papillomavirus (HPV); A Randomized Controlled Clinical Trial

Aim: Human Papillomavirus is one of the most crucial infectious disease in gynecology disease. To assess the efficacy of supplemental zinc treatment in clearance of HPV infection. Methods: Eighty zinc-sufficient women between 21-55 years, with positive HPV DNA testing, and abnormal cervical cytology in Pap test (ASCUS or LISL) were randomly divided to case (n=40) and control group (n=40). Case group received oral tablets of zinc sulfate twice a day for 3 months while control group received no placebo. During follow-up patients underwent repeat HPV DNA test and PAP test and were evaluated for clearance/persistence of HPV infection and regression/progression in the lesion grading. Results: As far as demographics, serum zinc levels and the relevant risk factors for persistence of HPV were concerned, there was no significant difference between two groups, except for the frequency distribution of HR-HPV which was significantly higher in case  group. Zinc treatment for 3 months reduced the risk of persistence of HPV infection and progression from baseline cytology (OR = 0.130) (CI 95% 0.04-0.381; p <0.001) and 0.301 (95% CI 0.777-0.116; p = 0.012), respectively. Age, initial cytology, HPV type, and contraceptive method were not related to persistence of HPV. Serum zinc levels increased in the casr group as a result of oral zinc consumption for 3-month period, though without any statistical significance (p = 0.407). Conclusion: The results of the following study suggested that oral intake of zinc sulfate supplement for 3 months increases the rates of HPV clearance and resolution of pre-existing cervical lesion.     

Electrochromic shift supports the membrane destabilization model of Tat-mediated transport and shows ion leakage during Sec transport

The mechanism and pore architecture of the Tat complex during transport of folded substrates remain a mystery, partly due to rapid dissociation after translocation. In contrast, the proteinaceous SecY pore is a persistent structure that needs only to undergo conformational shifts between “closed” and “opened” states when translocating unfolded substrate chains. Where the proteinaceous pore model describes the SecY pore well, the toroidal pore model better accounts for the high-energy barrier that must be overcome when transporting a folded substrate through the hydrophobic bilayer in Tat transport. Membrane conductance behavior can, in principle, be used to distinguish between toroidal and proteinaceous pores, as illustrated in the examination of many antimicrobial peptides as well as mitochondrial Bax and Bid. Here, we measure the electrochromic shift (ECS) decay as a proxy for conductance in isolated thylakoids, both during protein transport and with constitutively assembled translocons. We find that membranes with the constitutively assembled Tat complex and those undergoing Tat transport display conductance characteristics similar to those of resting membranes. Membranes undergoing Sec transport and those with the substrate-engaged SecY pore result in significantly more rapid electric field decay. The responsiveness of the ECS signal in membranes with active SecY recalls the steep relationship between applied voltage and conductance in a proteinaceous pore, while the nonaccelerated electric field decay with both Tat transport and the constitutive Tat complex under the same electric field is consistent with the behavior of a toroidal pore.

The twin arginine translocation pathway is uniquely able to transport fully folded substrates in an ATP-independent manner, relying instead on an electrochemical gradient (i.e., the proton motive force, or pmf) across the transporting membrane. It is crucial to the transport of substrates requiring various cofactors and hetero-oligomeric complexes in prokaryotes and of substrates vital to photosynthetic machinery in thylakoids (1). In plant mitochondria, the Rieske Fe/S protein required for the biogenesis of complex III is transported by the Tat pathway (2–6). It is implicated in both the virulence and antibiotic resistance of various infectious bacteria (7–12) and has been studied for its potential in biotechnology applications (13–15). The uniqueness of Tat functionality and its appearance across the kingdoms of life make it a valuable research target for crop modification, biotechnology, and pathogenesis. Unfortunately, much of the knowledge about its mechanism has been hard won, and the pore structure remains a mystery, likely due to the transient nature of the active complex.The active Tat complex in thylakoids consists of three core subunits, Tha4, Hcf106, and cpTatC, which are homologous to the bacterial TatA, TatB, and TatC, respectively (1, 16). An N-terminal signal peptide with a twin-arginine motif inserts into the cis-side leaflet at the TatBC receptor complex (17–19). Subsequent oligomerization of TatA subunits (20–22) at the TatBC receptor complex results in rings of varying sizes (22, 23), but it is unclear whether these structures represent transport pores. Of particular note is the short TatA transmembrane helix (TMH). Composed of only 16 residues, the solid-state NMR solution suggests that the TMH must tilt and draw a portion of the cis-side amphipathic helix (APH) into the membrane in order to cross the bilayer (24), establishing a resting state of hydrophobic mismatch. During transport, a conformational shift increasing the angle between the TMH and APH results in exacerbated hydrophobic mismatch, as the APH is moved radially away from the center and the TMH is pulled up toward the cis-side in the active state (25, 26). For both native and foreign substrates, the Tat-targeted signal peptide and the pmf are sufficient to cause assembly of the active translocon and achieve transport (27–31). After the translocation event, the complex dissociates into TatA and TatBC components (1, 15, 16) with the exception of some residual TatA bound to the receptor complex in a nonactive state and a spectrum of smaller TatA oligomers (32).Within the thylakoid membrane, it is useful to compare the Tat complex with the general secretory translocon (Sec) because they both function in the same membrane environment (1, 33). Sec translocation first requires recruitment of the substrate to the soluble SecA ATPase to form the substrate–SecA complex, which is then recruited to the SecY pore (1). In the inactive state, the proteinaceous SecY pore prevents ion leakage through a combination of a trans-side plug domain and an internal array of hydrophobic residues (34). Following substrate–SecA docking, a conformational shift in SecY allows substrate movement through the open pore in an ATP-dependent process driven by SecA (35). In the mammalian homolog Sec61, leakage of NAD⁺ ions is recorded during ribosome-bound nascent chain transport in a fluorescence quenching study, suggesting the pore can reach 4 to 6 nm in diameter (36). However, X-ray structures of substrate-fused SecA complexed with SecY (35), conductance studies in ribosome-bound substrates engaged with SecY (37), and SecY plug deletion mutants (38) in Escherichia coli have estimated the open SecY pore diameter to range from 7.3 to 8.8 Å, almost 10-fold lower. This small diameter likely contributes to the restriction of ion movement during Sec transport (39).While the Sec machinery only transports unfolded substrates (40), the Tat pore accommodates substrates ranging from a single unfolded chain in an engineered system (13) to a folded substrate with an average diameter of 70 Å (41). This extended size range raises an interesting question about the pore architecture. In the Sec translocon, X-ray crystallography of the SecY channel in Methanocaldococcus jannaschii (42) and Thermotoga maritima (43) reveals that the SecY pore channel excludes lipids in both the resting state and when engaged with its SecA partner. Further structural work on the E. coli substrate-engaged SecA–SecY complex shows that the SecY channel excludes lipids during transport as well (35). No such structural information about the Tat pore exists, but functional data suggest that TatA plays an important role in the pore (20, 44, 45) and cryogenic electron microscopy structures of TatA oligomers reveal rings of an internal diameter ranging from 30 to 70 Å (23). During transport of the 17-kDa subunit of the oxygen-evolving complex (OE23), the Tat pathway exhibits very low ion leakage (46), estimated to be less than 1 pS. This is despite the exchange of 80,000 protons per substrate (47). Extensive mapping of subunit–subunit and subunit–substrate contacts has revealed no putative plug domain (20, 48–51) that could be compared to that in the SecY protein.Pore architecture can be characterized by membrane conductance behavior. Conductance measured through proteinaceous pores representing the barrel-stave model has a very steep dependence on the voltage applied, whereas conductance in toroidal pores requires a larger voltage to be detected and increases more slowly in response to increasing voltage (52–54). Performing similar experiments on the Tat and Sec translocons would require functional reconstitution of both complexes into an in vitro setting. However, decay of the electrochromic shift (ECS) signal can be used as a measure of ion conductance (46). A transient absorption peak at ∼515 nm arising from carotenoid pigments in response to the native electric field generated by charge separation in the photosynthetic reaction centers (55) can be measured by delivering a single-saturating flash. The decay rate of such a signal is a direct measurement of how quickly the electric field is dissipated by ion movement across the membrane.In the experiments reported herein, ECS signal decay rates revealing the conductance states of resting isolated membranes and those engaged in ongoing transport and in the presence of a constitutively assembled and/or substrate-engaged translocon are used to probe the pore architecture in the Tat and Sec complexes. Increased conductance across the thylakoid membrane is indicated by a more rapidly decaying ECS signal. We find that conductance in thylakoid membranes during Sec-mediated transport and substrate-engaged SecY is consistently higher than that during Tat-mediated transport and with the constitutively assembled Tat complex, respectively, despite the much larger Tat pore required to transport a fully folded substrate. This points to a difference not only in mechanism but in pore architecture between the two. Conductance behavior of membranes undergoing Sec-mediated transport is consistent with that of a proteinaceous pore, while the resistance demonstrated by membranes undergoing Tat-mediated transport is more reminiscent of toroidal pores.     

Arginine-stabilized mPEG-PDLLA (50/50) polymeric micelles of docetaxel by electrostatic mechanism for tumor-targeted delivery

Abstract

Arginine-stabilized, docetaxel-loaded polymeric micelles (AR-DTX-PM) were prepared to enhance the physical stability of micelles and control the degradation of docetaxel (DTX). Amphiphilic diblock copolymers, methoxy-(Polyethylene Glycol)-block-Poly (D, L-lactide) (mPEG-PDLLA) were synthesized and used for the formulation of lyophilized DTX-PM powders. The micelles were found to have diameters of 20–30?nm with narrow polydispersity, and the entrapment efficiency was 90–100%. The accumulative release of AR-DTX-PM was higher than that of glucose-dispersed DTX-PM (Glu-DTX-PM). The results of both physical and chemical stability studies showed that the concentration of arginine required for optimum stability was 2.0?mg/ml. Preliminary investigation of the mechanisms of stabilization by arginine suggested that it is due to the electrostatic interaction as well as hydrogen bonds between DTX and arginine. The acute toxicity studies demonstrated that AR-DTX-PM was better tolerated in beagle dogs than DTX injection. However, the pharmacokinetic studies revealed no significant difference in C_max and AUC of AR-DTX-PM compared to DTX injection. When AR-DTX-PM was administrated at a dose of 30?mg/kg, the antitumor effect was stronger than that of commercial DTX injection at 10?mg/kg, and the increase of administration dose did not cause higher toxicity. The in vivo imaging test showed that the residence time of AR-DTX-PM at tumor sites was longer than its commercial formulation. In a word, it is expected that AR-DTX-PM can reduce systemic toxicity while retaining antitumor efficacy in cancer patients.     

Oral Zinc Sulfate as Adjuvant Treatment in Children With Nephrolithiasis: a Randomized,Double-Blind,Placebo-Controlled Clinical Trial

Background:

Nephrolithiasis in children is associated with a high rate of complications and recurrence.

Objectives:

Since some evidences reported that zinc has an important place amongst inhibitors of crystallization and crystal growth, we decided to assess the effectiveness of oral zinc sulfate as adjuvant treatment in children with nephrolithiasis.

Patients and Methods:

This was a randomized, double-blind, placebo-controlled clinical trial. 102 children in the age range 1 month to 11 years with first nephrolithiasis were recruited. Patients were randomly divided into two equal groups (intervention and control groups). Intervention group received conservative measures for stones and 1 mg/kg/day (maximum 20 mg/day) oral zinc sulfate syrup for 3 months. Control group received placebo in addition to conservative measures, also for 3 months. Patients were followed up by ultrasonography for 9 months, in 5 steps (at the end of 1st, 2nd, 3rd, 6th and 9th month after treatment) assessing size and number of stones in the kidneys.

Results:

Only at the end of the first month, the average number (intervention: 1.15 ± 3.78, control: 1.3 ± 2.84) (P = 0.001) and size (cm) (intervention: 0.51 ± 1.76, control: 0.62 ± 1.39) (P = 0.001) of stones was significantly lower in the intervention group, and in other points there was no significant therapeutic efficacy in oral zinc adjuvant treatment compared to conservative treatment alone. Also, during the 9-month follow-up, the number and size of stones in both groups decreased significantly (both: P < 0.0001) in a way that the decrease in the intervention group showed no difference with the control group.

Conclusions:

Adjuvant treatment with zinc is not more effective than consecutive treatment in children with nephrolithiasis. However, further studies are recommended due to the lack of clinical evidence in this field.     

Aquaretics in cirrhotics with hyponatremia

Abstract   Hyponatremia develops spontaneously or following diuretic therapy in about one-third of patients with cirrhosis. The development of hyponatremia leads to fluid restriction which is unpopular with patients and limits the usefulness of diuretics. The principle factor that leads to hyponatremia in the cirrhotic is an increase in the non-osmotic release of arginine vasopressin (AVP) and subsequent impaired clearance of free water by the kidney. The development of vasopressin receptor antagonists and Κ-opioid agonists has led to trials examining their efficacy in the treatment of hyponatremia in cirrhosis. The vasopressin receptor antagonists have been shown to improve free water clearance and raise serum sodium in decompensated cirrhotics in short-term studies. The utility of these agents for the long-term management of hyponatremia and in preventing the development of hyponatremia associated with diuretic usage remains to be determined.