Microbial resistance to classical antibiotics and its rapid progression have raised serious concern in the treatment of infectious diseases. Recently, many studies have been directed towards finding promising solutions to overcome these problems. Phytochemicals have exerted potential antibacterial activities against sensitive and resistant pathogens via different mechanisms of action. In this review, we have summarized the main antibiotic resistance mechanisms of bacteria and also discussed how phytochemicals belonging to different chemical classes could reverse the antibiotic resistance. Next to containing direct antimicrobial activities, some of them have exerted in vitro synergistic effects when being combined with conventional antibiotics. Considering these facts, it could be stated that phytochemicals represent a valuable source of bioactive compounds with potent antimicrobial activities.

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The aim of this study was to evaluate the antileishmanial effects of topical liposomal paromomycin sulfate (PM) in Leishmania major-infected BALB/c mice. Liposomes containing 10 or 15% PM (Lip-PM-10 and Lip-PM-15, respectively) were prepared by the fusion method and were characterized for their size and encapsulation efficiency. The penetration of PM from the liposomal PM formulations (LPMFs) through and into skin was evaluated in vitro with Franz diffusion cells fitted with mouse skin at 37°C for 8 h. The in vitro permeation data showed that almost 15% of the LPMFs applied penetrated the mouse skin, and the amount retained in the skin was about 60% for both formulations. The 50% effective doses of Lip-PM-10 and Lip-PM-15 against L. major promastigotes in culture were 65.32 and 59.73 g/ml, respectively, and those against L. major amastigotes in macrophages were 24.64 and 26.44 g/ml, respectively. Lip-PM-10 or Lip-PM-15 was used topically twice a day for 4 weeks to treat L. major lesions on BALB/c mice, and the results showed a significantly (P < 0.001) smaller lesion size in the mice in the treated groups than in the mice in the control group, which received either empty liposomes or phosphate-buffered saline (PBS). Eight weeks after the beginning of the treatment, every mouse treated with LPMFs was completely cured. The spleen parasite burden was significantly (P < 0.001) lower in mice treated with Lip-PM-10 or Lip-PM-15 than in mice treated with PBS or control liposomes, but no significant difference was seen between the two groups treated with either Lip-PM-10 or Lip-PM-15. The results suggest that topical liposomal PM may be useful for the treatment of cutaneous leishmaniasis.Leishmaniasis, which has diverse clinical manifestations, is caused by different species of Leishmania and is endemic in many countries (49). Although cutaneous leishmaniasis (CL) is a self-healing disease, healing takes a long time, and healing times of even up to 2 years have been reported (37). Pentavalent antimonials, which are still the first-line treatment for CL, require multiple injections and are painful; as such, they are not tolerated by most of the patients and, moreover, are not always effective. In addition, resistance to pentavalent antimonials has been reported (12,13,33).Paromomycin sulfate (PM) was reported to show anti-Leishmania activity in the 1960s, and since then PM showed promising activity against both CL and visceral leishmaniasis (VL) in clinical trials (13, 31). Recently, the parenteral formulation of PM has been approved for use for the treatment of VL (27). Nevertheless, the systemic use of PM might cause nephrotoxicity. The conventional topical dosage forms of PM have been tested in clinical trials for their activities against CL and showed promising results, but acceptable efficacy was not always seen (2,3,5,13,18,23,28,43). The formidable barrier nature of the stratum corneum (SC) of the skin does not allow the penetration of drugs with high hydrophilicities and molecular weights, like PM (19). Furthermo...

In this article, bone cells and their intercellular communications have been reviewed. Gap junctions and hemichannels are the main routes of interactions in bone tissue. They play a substantial role in survival and cell death, since pro-apoptotic signals can propagate through them. Different adhesion molecules are required for apoptosis, particularly caspase family as well as noncaspase proteases. The disruption outcome of apoptosis could result in bone-related diseases such as osteonecrosis. Anti-apoptotic strategies include inhibition of caspase, poly [ADP-ribose] polymerase (PARP), and Bcl-2 proteins as well as induction of the PKB/Akt pathway and inhibitors of apoptosis (IAP) family of proteins. Thus, understanding the mechanism of apoptosis gives detailed insights of anti-apoptotic molecular targets. Based on these targets, different treatments were designed and produced such as estrogen replacement therapy, administration of different bisphosphonates, raloxifene, calcitonin, sodium fluoride, calcium, and vitamin D. As a result, new applicable drugs for treatment of related bone problems can be proposed for clinical approach especially in the early stage of diseases.

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The ferrichrome-iron receptor of Escherichia coli K-12 is FhuA (Me, 78,992), the first component of an energy-dependent, high-affinity iron uptake pathway. FhuA is also the cognate receptor for bacteriophages T5, Ti, +80, and UC-1, for colicin M and microcin 25, and for albomycin. To probe the topological organization of FhuA which enables recognition of these different ligands, we generated a library of 16 Under conditions of iron deprivation, many gram-negative bacteria derepress the expression of a class of surface receptors called iron-regulated outer membrane proteins. The function of these proteins is to bind specific siderophores and to initiate their internalization, thereby enabling the cell to satisfy its iron requirement (5). Siderophores have widely differing structures, but all share a high affinity for the ferric ion (24). Assimilation of the ferric siderophore requires a specific receptor as well as other periplasmic and cytoplasmic membrane proteins, including TonB (28). A cytoplasmic membrane protein complex including TonB, ExbB, and ExbD is thought to couple the electrochemical potential of the cytoplasmic membrane to the outer membrane siderophore receptor, a step which allows subsequent translocation of the bound ligand into the periplasm (37,38 proteins, including FepA (26), FhuA (23), FoxA (1), and LamB (9). These models incorporate some structural elements in common: amphiphilic sequences constitute antiparallel 3 sheets which traverse the outer membrane; intervening sequences are thought to constitute loops that are exposed at the cell surface or in the periplasm.Predictions of outer membrane protein topology can be evaluated with a number of tools, including monoclonal antibodies (MAbs) (26,34,39), insertion and deletion mutagenesis (4, 6, 7, 23), and reporter protein fusions (27)

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