Brain myo-inositol level is elevated in Ts65Dn mouse and reduced after lithium treatment

The segmental trisomy Ts65Dn mouse is a novel model of Down syndrome (DS). The purpose of this study was to measure brain levels of myo-inositol (ml), N-acetylaspartate (NAA), and other metabolites in Ts65Dn mice using in vivo 1H magnetic resonance spectroscopy (MRS), and to determine whether lithium (Li) treatment alters brain ml level. The ratio of ml over total creatine (Cr), ml/Cr, was significantly elevated (mean change +38%), while NAA/Cr was significantly decreased (mean change -18%) in Ts65Dn mice (n=5) compared with control mice (n= 7). This is consistent with 1H MRS findings in DS human adults. Brain ml/Cr of the entire sample group (n= 12) was reduced (mean change -15%) following Li treatment, supporting the Li-induced ml depletion hypothesis.     

Exploring the therapeutic mechanisms of Cassia glauca in diabetes mellitus through network pharmacology,molecular docking and molecular dynamics

Cassia glauca is reported as anti-diabetic medicinal plant and is also used as an ethnomedicine. However, its mode of action as an anti-diabetic agent has not been clearly elucidated. Hence, the present study investigated the probable mechanism of action of C. glauca to manage diabetes mellitus via network pharmacology and molecular docking and simulations studies. The reported bioactives from C. glauca were retrieved from an open-source database, i.e. ChEBI, and their targets were predicted using SwissTargetPrediction. The proteins involved in the pathogenesis of diabetes were identified from the therapeutic target database. The targets involved in diabetes were enriched in STRING, and the pathways involved in diabetes were identified concerning the KEGG. Cytoscape was used to construct the network among bioactives, proteins, and probably regulated pathways, which were analyzed based on edge count. Similarly, molecular docking was performed using the Glide module of the Schrodinger suite against majorly targeted proteins with their respective ligands. Additionally, the drug-likeness score and ADMET profile of the individual bioactives were predicted using MolSoft and admetSAR2.0 respectively. The stability of these complexes were further studied via molecular dynamics simulations and binding energy calculations. Twenty-three bio-actives were retrieved from the ChEBI database in which cassiarin B was predicted to modulate the highest number of proteins involved in diabetes mellitus. Similarly, GO analysis identified the PI3K-Akt signaling pathway to be primarily regulated by modulating the highest number of gene. Likewise, aldose reductase (AKR1B1) was majorly targeted via the bioactives of C. glauca. Similarly, docking study revealed methyl-3,5-di-O-caffeoylquinate (docking score −9.209) to possess the highest binding affinity with AKR1B1. Additionally, drug-likeness prediction identified cassiaoccidentalin B to possess the highest drug-likeness score, i.e. 0.84. The molecular dynamics simulations and the MMGBSA indicate high stability and greater binding energy for the methyl-3,5-di-O-caffeoylquinate (ΔG_bind = −40.33 ± 6.69 kcal mol⁻¹) with AKR1B1, thus complementing results from other experiments. The study identified cassiarin B, cassiaoccidentalin B, and cinnamtannin A2 as lead hits for the anti-diabetic activity of C. glauca. Further, the PI3K-Akt and AKR1B1 were traced as majorly modulated pathway and target, respectively.

Cassia glauca is reported for anti-diabetic action and is also used as an ethnomedicine.     

Improved Delivery Through Biological Membranes LX: Intradermal Targeting of Acyclovir Using Redox-Based Chemical Drug Delivery Systems

Two types of novel chemical drug delivery systems (CDS's) for acyclovir, A-CDS-1 (based on oxidation, which utilized the 1,4-dihydrotrigonelline moiety) and A-CDS-2 (based on reduction, which utilized the lipoic acid moiety), were designed to create reservoirs of metabolic precursors for the enhanced local delivery of the antiviral agent acyclovir to the skin. They were evaluated in two-compartment diffusion cells using hairless-mouse skin in vitro. This approach could be useful in the treatment of mucocutaneous herpes simplex virus (HSV-1) infection in the epidermal region of the skin. Upon application to the freshly excised hairless-mouse skin, A-CDS-1 was rapidly oxidized to form the quaternary metabolite AQ⁺, which was extensively localized in the skin. AQ⁺ then served as a reservoir for the release of the antiviral agent in the skin. A-CDS-1 delivered almost equivalent amounts of acyclovir not only to the skin but also transdermally. On the other hand, A-CDS-2 specifically localized acyclovir delivery to the skin as opposed to transdermal delivery. Due to their redox properties, both CDS's demonstrated significant depot formation of metabolic precursors, thus enhancing intradermal acyclovir delivery. The CDS's exhibited greater skin membrane partition coefficients than the parent underivatized acyclovir and were able to release the antiviral agent in the skin tissue. The CDS's were susceptible to hydrolysis in biological media, resulting in the release of acyclovir under near physiological conditions. Thus, the CDS's can serve to enhance intradermal targeting and delivery of the antiviral agent acyclovir.     

Targeting the cerebrovascular large neutral amino acid transporter (LAT1) isoform using a novel disulfide-based brain drug delivery system

We describe a novel strategy to achieve high affinity recognition for the specific, cerebrovascular large neutral amino acid transporter (LAT1) isoform by covalent coupling of small molecules to the amino acid, L-cysteine (L-Cys). L-Cys (as the carrier) was covalently attached via a disulfide bond to either 6-mercaptopurine or 2-methyl-1-propanethiol (IBM) to form the brain-targeted drug delivery systems (BTDS). BTDS were designed for high affinity recognition by LAT1 at the cerebrovasculature. Using an in situ rat brain perfusion technique, competition between BTDS and the radiotracer [¹⁴C]L-Leu demonstrated significant inhibition of [¹⁴C]L-Leu brain uptake. BTDS possess affinity for cerebrovascular LAT1 in many distinct brain compartments, and the recognition of BTDS by LAT1 is influenced by hydrophobicity of the side-chain in BTDS. Thus, the BTDS strategy may be utilized for rapid shuttling of various neuropharmaceuticals into brain.     

Modulating blood-brain barrier interactions of amino acid-based anticancer agents

The large neutral amino acid (LNAA) transporter at the blood-brain barrier (BBB) mediates brain uptake of amino acid-based anticancer agents (e.g., melphalan and acivicin). In this study, we blocked the amino acid terminus of the anticancer agents using a bioreductive drug delivery system (TDDS). This molecular modification of the anticancer agents is expected to prevent LNAA carrier-mediated transport across the BBB. In this study, we demonstrate that the parent amino acid containing anticancer agents are substrates for the LNAA transporter at the BBB, whereas the TDDS is not recognized by the LNAA transporter. An in situ rat brain perfusion technique was used to determine competition for LNAA carrier-mediated transport at the BBB using [¹⁴C]L-leucine. The BBB capillary permeability-surface area (PA) product for the radiotracer [¹⁴C]L-leucine (control) was determined to be 5.18 +/- 0.32 x 10^-2 ml/s/g (100%). The control PA value for [¹⁴C]L-leucine was competitively inhibited (down to 7-18% of control) by excess L-phenylalanine as well as by excess concentration of the anticancer amino acids, melphalan and acivicin, showing competition for the LNAA transporter at the BBB. In contrast, brain perfusion of [¹⁴C]L-leucine in presence of excess TDDS resulted in no competition for brain uptake of [¹⁴C]L-leucine via the LNAA transporter. Thus, bioreversible derivatization of the parent anticancer amino acids resulted in blocking the amino acid functional group, thereby leading to loss of recognition for the cerebrovascular LNAA transporter at the BBB.     

Lead exposures increases oxidative stress in serum deprived E14 mesencephalic cultures. Role of metallothionein and glutathione

E14 mesencephalic cultures grown 6 days in Neurobasal Medium containing 10% horse serum consist of differentiated neurons and astroglia. In these cultures, glutathione and metallothionein-I/II are enriched in astrocytes and play an important role in heavy metal scavenging and oxidative stress response. A 24 h exposure to 25 micro M Pb, in serum-containing medium, elevated the glutathione content by more than twofold and increased the metallothionein I/II-immunolabeled protein band. In contrast, exposure to 3 to 25 micro M Pb is serum-free medium increased Pb uptake by cells 2 to 4-times above the levels found in 10% serum-containing medium, reduced the glutathione level and obliterated the metallothionein-I/II protein band. The rapid decrease of metallothionein-I/II and glutathione levels in serum-free medium implies that their regulation may depend on a serum factor operative in inducing immediate early genes. Exposure to 6 micro M Pb in serum-free or in B27-supplemented medium increased the carbonyl content of several protein bands above control levels indicating that under conditions that curtail metallothionein induction Pb exposure causes increased oxidative stress.     

Hydrogen Bonding Potential as a Determinant of the in Vitro and in Situ Blood–Brain Barrier Permeability of Peptides

With the exception of various central nervous system (CNS)-required nutrients for which specific, saturable transport systems exist, the passage of most water-soluble solutes through the blood–brain barrier (BBB) is believed to depend largely on the lipid solubility of the solutes. Most peptides, therefore, do not enter the CNS because of their hydrophilic character. Recently, utilizing homologous series of model peptides and Caco-2 cell monolayers as a model of the intestinal mucosa, it was concluded that the principal determinant of peptide transport across the intestinal cellular membrane is the energy required to desolvate the polar amide bonds in the peptide (P. S. Burton et al., Adv. Drug Deliv. Rev. 7:365–386, 1991). To determine whether this correlation can be extended to the BBB, the permeabilities of the same peptides were determined using an in vitro as well as an in situ BBB model. The peptides, blocked on the N- and C-terminal ends, consisted of D-phenylalanine (F) residues: AcFNH₂, AcF₂NH₂, AcF₃NH₂, AcF₂(NMeF)NH₂, AcF(NMeF)₂NH₂, Ac(NMeF)₃NH₂, and Ac(NMeF)₃NHMe. A good correlation among the permeabilities of these model peptides across the bovine brain microvessel endothelial cell (BBMEC) monolayers, an in vitro model of the BBB, and their permeabilities across the BBB in situ was observed (r = 0.928, P < 0.05). The permeabilities of these peptides did not correlate with the octanol–buffer partition coefficients of the peptides (r = 0.389 in vitro and r = 0.155 in situ; P < 0.05). However, correlations were observed between the permeabilities of these peptides and the number of potential hydrogen bonds the peptides can make with water (r = 0.837 in vitro and r = 0.906 in situ; P < 0.05), suggesting that desolvation of the polar bonds in the molecule is a determinant of permeability. Consistent with this, good correlations were found between the permeabilities of these peptides and their partition coefficients between heptane–ethylene glycol (r = 0.981 in vitro and r = 0.940 in situ ; P < 0.05) or the differences in partition coefficients between octanol–buffer and isooctane–buffer (logPC) (r = 0.961 in vitro and r = 0.962 in situ; P < 0.05), both of which are experimental estimates of hydrogen bond or desolvation potential. These results suggest that the permeability of peptides through the BBB is governed by the same physicochemical parameter (hydrogen bonding potential) as their permeability through the intestinal mucosa.     

Carboplatin hypersensitivity

Carboplatin has established an important role in many different cancers. As its use increased, the documented cases of hypersensitivity also picked up. Although the mechanism of these reactions remains unknown, the immediate type of hypersensitivity reaction mediated by IgE may be involved. It takes a while for the reaction to develop, but cases are reported even after 1st cycle. The incidence of hypersensitivity is highest at about 8th cycle of therapy with decline after that. These reactions themselves ranged from facial flushing or itching to seizures, dyspnea, and anaphylaxis. Many physicians currently do not use skin testing prior to 8th cycle of carboplatin therapy and retreat their patients with carboplatin after the first hypersensitivity reaction. Therefore, it is suggested that skin test should be conducted prior to the 8th cycle, preferably before the 6th cycle, as hypersensitivity tends to increase on the 6th cycle-treatment. Methods published so far involve: desensitization, skin testing, switching therapy to another platinum analogue, and premedication. Despite all the process, the most effective drug toxicity prevention method remains skin testing prior to 8th cycle. It can accurately predict patients who will develop hypersensitivity reactions. Other methods so far have not shown consistent results.