5785486
Identification of the site of photocross-linking formed in the absence of magnesium nucleotide from SH2 (Cys-697) in myosin subfragment 1 labeled with 4'-maleimidylbenzophenone.
The site of photocross-linking between Cys-697 (SH2), prelabeled with 4'-[14C]maleimidylbenzophenone, and the 50-kDa segment of myosin S1 on irradiation in the absence of nucleotide has been determined by isolation of the 20-50-kDa adduct and subsequent tryptic proteolysis. Isolation and partial sequencing of the radioactively labeled peptide indicate that the site of cross-linking is Arg-239. This result indicates that, in the absence of nucleotide, Arg-239 resides at about 1.0 nm from SH2 and, on the basis of the recent work of Sutoh and Hiratsuka (Sutoh, K. and Hiratsuka T. (1988) Biochemistry 27, 2964-2969) places Arg-239 at no more than 1.45 nm from either Lys-184 or Lys-189 of the nucleotide-binding "glycine-rich" loop prior to the binding of nucleotide.
33705616
Anticancer potential of silymarin: from bench to bed side.
Silymarin consists of a family of flavonoids (silybin, isosilybin, silychristin, silydianin and taxifoline) commonly found in the dried fruit of the milk thistle plant Silybum marianum. Although silymarin's role as an antioxidant and hepatoprotective agent is well known, its role as an anticancer agent has begun to emerge. Extensive research within the last decade has shown that silymarin can suppress the proliferation of a variety of tumor cells (e.g., prostate, breast, ovary, colon, lung, bladder); this is accomplished through cell cycle arrest at the G1/S-phase, induction of cyclin-dependent kinase inhibitors (such as p15, p21 and p27), down-regulation of anti-apoptotic gene products (e.g., Bcl-2 and Bcl-xL), inhibition of cell-survival kinases (AKT, PKC and MAPK) and inhibition of inflammatory transcription factors (e.g., NF-kappaB). Silymarin can also down-regulate gene products involved in the proliferation of tumor cells (cyclin D1, EGFR, COX-2, TGF-beta, IGF-IR), invasion (MMP-9), angiogenesis (VEGF) and metastasis (adhesion molecules). The antiinflammatory effects of silymarin are mediated through suppression of NF-kappaB-regulated gene products, including COX-2, LOX, inducible iNOS, TNF and IL-1. Numerous studies have indicated that silymarin is a chemopreventive agent in vivo against a variety of carcinogens/tumor promoters, including UV light, 7,12-dimethylbenz(a)anthracene (DMBA), phorbol 12-myristate 13-acetate (PMA) and others. Silymarin has also been shown to sensitize tumors to chemotherapeutic agents through down-regulation of the MDR protein and other mechanisms. It binds to both estrogen and androgen receptors, and down-regulates PSA. In addition to its chemopreventive effects, silymarin exhibits antitumor activity against human tumors (e.g., prostate and ovary) in rodents. Various clinical trials have indicated that silymarin is bioavailable and pharmacologically safe. Studies are now in progress to demonstrate the clinical efficacy of silymarin against various cancers.
36556551
Glutathione S-transferase-dependent conjugation of leukotriene A4-methyl ester to leukotriene C4-methyl ester in mammalian skin.
The glutathione S-transferase (GST)-dependent conjugation of reduced glutathione (GSH) with leukotriene A4 (LTA4)-methyl ester in rodent and human skin was investigated. Incubation of [3H]LTA4-methyl ester (1 nmole, approximately 200,000 dpm) with cytosol prepared from rat, mouse and human skin or with affinity purified GST from rat skin cytosol in the presence of GSH resulted in the formation of LTC4-methyl ester. Maximum enzyme activity was observed in rat skin followed by mouse and human skin. With heat-denatured cytosol or in the absence of GSH, the product formation was negligible. GST purified from rat skin cytosol by GSH-agarose affinity chromatography exhibited a several-fold increase in the specific activity of enzyme with 1-chloro-2,4-dinitrobenzene (55-fold), ethacrynic acid (67-fold) and LTA4-methyl ester (12-fold) as substrates. Western blot analysis of the affinity purified GST indicated a predominant expression of the Pi class of GST isozyme followed by Mu and Alpha classes of isozymes. The formation of LTC4-methyl ester was established by its radioactivity profile on high pressure liquid chromatography and absorption spectroscopy. These results suggest that, in addition to xenobiotic metabolism, cutaneous GSTs may also be capable of metabolizing physiological substrates such as LTA4.
12257571
Protection against ultraviolet B radiation-induced effects in the skin of SKH-1 hairless mice by a polyphenolic fraction isolated from green tea.
In prior studies we and others have shown that oral feeding of a polyphenolic fraction isolated from green tea (GTP) or water extract of green tea affords protection against ultraviolet B (UVB) radiation-induced carcinogenesis in SKH-1 hairless mice (Wang et al., Carcinogenesis 12, 1527-1530, 1991). It is known that exposure of murine skin to UVB radiation results in cutaneous edema, depletion of the antioxidant-defense system and induction of ornithine decarboxylase (ODC) and cyclooxygenase activities. In this study we assessed the protective effect of GTP on these UVB radiation-caused changes in murine skin. Oral feeding of 0.2% GTP (wt/vol) as the sole source of drinking water for 30 days to SKH-1 hairless mice followed by irradiation with UVB (900 mJ/cm2) resulted in significant protection against UVB radiation-caused cutaneous edema (P < 0.0005) and depletion of the antioxidant-defense system in epidermis (P < 0.01-0.02). The oral feeding of GTP also resulted in significant protection against UVB radiation-caused induction of epidermal ODC (P < 0.005-0.01) and cyclooxygenase activities (P < 0.0001) in a time-dependent manner. Our data indicate that the inhibition of UVB radiation-caused changes in these markers of tumor promotion in murine skin by GTP may be one of the possible mechanisms of chemopreventive effects associated with green tea against UVB-induced tumorigenesis. The results of this study suggest that green tea, specifically polyphenols present therein, may be useful against inflammatory responses associated with the exposure of skin to solar radiation.
37464296
Introduction to Special Issue on Molecular Basis for Cancer Prevention with Bioactive Food Components in Nutrition and Cancer--an International Journal.
The advance of technology and understanding of the process of cancer development suggests that the reported lesser incidence and death due to cancer in countries other than the Western and European countries might also be due to under- diagnosed and under-represented cases. Further, increases in life span as well as ignorance about the disease puts populations in South and South East Asian countries at higher risk to develop cancer. With the increasing rate of cancer incidence every year in non -Western countries, cancer is estimated to become the deadliest disease in coming decades. Conventional chemo- and radio-therapies during the past three decades have not been able to contain the disease, and also have serious side effects. Many natural agents, especially small molecules from plants are non-toxic, easily available and may have anticancer potential. Thus, screening phytochemicals as anticancer agents could be a better approach in cancer prevention and treatment. This chemoprevention approach may have translational significance for prevention and treatment of cancer. 
 
Therefore to emphasize the potential role of phytochemicals in cancer prevention and therapy, it was our privilege to host the International Symposium on Recent Advances in Cancer Research: Therapeutics to Chemoprevention, at Central University of Gujarat (CUG), Gandhinagar. The conference was co-organized by the University of Colorado Denver, USA; University of Pittsburgh, USA; University of Oklahoma, USA, during 8–9 February, 2012. Modern biological strategies, specifically the latest developments for the targeted prevention and treatment of cancer via dietary, natural and synthetic agents were discussed in detail. The symposium also emphasized the translational aspect of cancer chemoprevention strategies for various cancers. 
 
The symposium deliberations include the ideas for combinatorial chemoprevention by phytochemicals as a promising approach for cancer control and emerging trends for the use of herbal radio-modulators to sensitize the cancer cells for apoptotic cell death. Many bioactive phytochemicals such as silibinin, benzyl isothiocyanate, anthocyanidins, nexrutine, tocopherol, etc. were discussed for their in vivo efficacy in animal tumor models, associated mechanisms and translational potential. Targeting tumor microenvironment with small molecules was found promising and having translational potential for prostate and breast cancer chemoprevention. 
 
The novel work and ideas presented at the symposium were helpful in guiding the research orientation of scientists, especially the young researchers who will be benefitted at all levels of their career development. Since chemoprevention of cancer is becoming an attractive approach for controlling cancer, we felt that the deliberations of this symposium should reach to the wider section of the researchers. Therefore, it was planned to bring out a special issue on Molecular Basis for Cancer Prevention with Bioactive Food Components in Nutrition and Cancer – An International Journal. We appreciate the researchers for contributing their novel work and ideas to this special issue. We are grateful to the Editor of Nutrition and Cancer – An International Journal, for his initiative to bring out this special issue on this relevant topic. We believe that this volume will be enlightening for the researchers working in the area of cancer chemoprevention.
35457752
Nordihydroguaiaretic acid, an inhibitor of lipoxygenase, also inhibits cytochrome P-450-mediated monooxygenase activity in rat epidermal and hepatic microsomes.
Nordihydroguaiaretic acid (NDGA), a plant lignan and phenolic antioxidant, is a known lipoxygenase inhibitor. In this study, we investigated the effect of NDGA on rat epidermal and hepatic monooxygenase activity and its interaction with rat hepatic microsomal cytochrome P-450. The addition of NDGA to epidermal microsomes prepared from control and 3-methylcholanthrene (3-MC)-pretreated rats and hepatic microsomal preparations from control, 3-MC-pretreated, and phenobarbital (PB)-pretreated rats resulted in a concentration-dependent inhibition of aryl hydrocarbon hydroxylase (AHH) and 7-ethoxyresorufin O-deethylase (ERD) activities. The 50% inhibitory dose for NDGA ranged from 4.1 x 10(-5) to 13.1 x 10(-5) M for AHH and ERD activities in these microsomal preparations. The addition of NDGA to hepatic microsomes prepared from PB-pretreated rats resulted in spectral changes characterized by absorbance maxima at 380 nm and minima at 414 nm, typical of type I binding difference spectra. It also showed time- and concentration-dependent inhibition of the binding of carbon monoxide to dithionite or NADPH-reduced cytochrome P-450. We speculate that perhaps hydroxyl groups present in NDGA play an important role in inhibiting the monooxygenase activity and suggest that NDGA may have potential as an antimutagen and/or anticarcinogen. Furthermore, caution must be exercised in elucidating the role of lipoxygenase in metabolic pathways based solely on the criterion of inhibition by NDGA.
24077597
Allergic bronchopulmonary aspergillosis: review of literature and proposal of new diagnostic and classification criteria.
Allergic bronchopulmonary aspergillosis (ABPA) is an immunological pulmonary disorder caused by hypersensitivity to Aspergillus fumigatus, manifesting with poorly controlled asthma, recurrent pulmonary infiltrates and bronchiectasis. There are estimated to be in excess of four million patients affected world-wide. The importance of recognizing ABPA relates to the improvement of patient symptoms, and delay in development or prevention of bronchiectasis, one manifestation of permanent lung damage in ABPA. Environmental factors may not be the only pathogenetic factors because not all asthmatics develop ABPA despite being exposed to the same environment. Allergic bronchopulmonary aspergillosis is probably a polygenic disorder, which does not remit completely once expressed, although long-term remissions do occur. In a genetically predisposed individual, inhaled conidia of A. fumigatus germinate into hyphae with release of antigens that activate the innate and adaptive immune responses (Th2 CD4(+) T cell responses) of the lung. The International Society for Human and Animal Mycology (ISHAM) has constituted a working group on ABPA complicating asthma (www.abpaworkinggroup.org), which convened an international conference to summarize the current state of knowledge, and formulate consensus-based guidelines for diagnosis and therapy. New diagnosis and staging criteria for ABPA are proposed. Although a small number of randomized controlled trials have been conducted, long-term management remains poorly studied. Primary therapy consists of oral corticosteroids to control exacerbations, itraconazole as a steroid-sparing agent and optimized asthma therapy. Uncertainties surround the prevention and management of bronchiectasis, chronic pulmonary aspergillosis and aspergilloma as complications, concurrent rhinosinusitis and environmental control. There is need for new oral antifungal agents and immunomodulatory therapy.
21302804
Structural analysis of a ternary complex of allantoate amidohydrolase from Escherichia coli reveals its mechanics.
Purine metabolism plays a major role in regulating the availability of purine nucleotides destined for nucleic acid synthesis. Allantoate amidohydrolase catalyzes the conversion of allantoate to (S)-ureidoglycolate, one of the crucial alternate steps in purine metabolism. The crystal structure of a ternary complex of allantoate amidohydrolase with its substrate allantoate and an allosteric effector, a sulfate ion, from Escherichia coli was determined to understand better the catalytic mechanism and substrate specificity. The 2.25 A resolution X-ray structure reveals an alpha/beta scaffold akin to zinc exopeptidases of the peptidase M20 family and lacks the (beta/alpha)(8)-barrel fold characteristic of the amidohydrolases. Arrangement of the substrate and the two co-catalytic zinc ions at the active site governs catalytic specificity for hydrolysis of N-carbamyl versus the peptide bond in exopeptidases. In its crystalline form, allantoate amidohydrolase adopts a relatively open conformation. However, structural analysis reveals the possibility of a significant movement of domains via rotation about two hinge regions upon allosteric effector and substrate binding resulting in a closed catalytically competent conformation by bringing the substrate allantoate closer to co-catalytic zinc ions. Two cis-prolyl peptide bonds found on either side of the dimerization domain in close proximity to the substrate and ligand-binding sites may be involved in protein folding and in preserving the integrity of the catalytic site.
28689596
Overcoming barriers that inhibit proper treatment of anemia.
Intravenous (i.v.) iron and recombinant human erythropoietin (EPO), like all other medications, are associated with the risk of adverse events. Historically, the primary concern with iron therapy has been the possibility of iron overload, which exposes the individual to the effects associated with nontransferrin-bound iron. Experience with EPO use has demonstrated an association with hypertension and with the upregulation of a number of markers of inflammation. The impact of these potential adverse effects merits careful analysis, given that both i.v. iron and EPO are designed for long-term use in a patient population at high risk for infection and cardiovascular disease. However, the incidence of iron overload and the risks associated with nontransferrin-bound iron have dramatically been reduced since the introduction of EPO therapy, and no data exist that demonstrate a definitive association between i.v. iron and an increased risk of morbidity related to infection or cardiovascular disease. On the other hand, EPO use is associated with hypertension, endothelial dysfunction, and prothrombotic and inflammatory states in hemodialysis patients. Risks associated with hypertension can be minimized by using the lowest effective EPO dose, which may be achieved through the regular use of i.v. iron. Judicious use of both i.v. iron and EPO may optimize cardiovascular outcomes.
36745510
Iron sucrose causes greater proteinuria than ferric gluconate in non-dialysis chronic kidney disease.
Non-dextran intravenous (i.v.) iron preparations seem to differentially affect proteinuria in patients with chronic kidney disease. To study effects of ferric gluconate and iron sucrose on proteinuria, we conducted a crossover trial in 12 patients with stage 3-4 chronic kidney disease. These patients were randomized to receive the same dose of either drug 1 week apart. Urine samples were obtained immediately before and at frequent intervals after the drug. The urine total protein/creatinine ratio was significantly greater after iron sucrose than ferric gluconate treatment with the effect noted within 15 min post-infusion. Furthermore, when iron sucrose was given first, a significantly greater protein/creatinine ratio was seen subsequently with ferric gluconate than with the reverse order of treatment. The urine albumin/creatinine ratio was also significantly greater with iron sucrose than with ferric gluconate. There was no significant difference, however, between the two i.v. irons in the measured urine N-acetyl-beta-D-glucosaminidase/creatinine ratio. Although our study showed that acutely, iron sucrose increased proteinuria, the long-term effects of repeated i.v. non-dextran iron on kidney function requires further study.
20316893
Structure of human dual specificity protein phosphatase 23, VHZ, enzyme-substrate/product complex.
Protein phosphorylation plays a crucial role in mitogenic signal transduction and regulation of cell growth and differentiation. Dual specificity protein phosphatase 23 (DUSP23) or VHZ mediates dephosphorylation of phospho-tyrosyl (pTyr) and phospho-seryl/threonyl (pSer/pThr) residues in specific proteins. In vitro, it can dephosphorylate p44ERK1 but not p54SAPK-beta and enhance activation of c-Jun N-terminal kinase (JNK) and p38. Human VHZ, the smallest of the catalytically active protein-tyrosine phosphatases (PTP) reported to date (150 residues), is a class I Cys-based PTP and bears the distinctive active site signature motif HCXXGXXRS(T). We present the crystal structure of VHZ determined at 1.93A resolution. The polypeptide chain adopts the typical alphabetaalpha PTP fold, giving rise to a shallow active site cleft that supports dual phosphorylated substrate specificity. Within our crystals, the Thr-135-Tyr-136 from a symmetry-related molecule bind in the active site with a malate ion, where they mimic the phosphorylated TY motif of the MAPK activation loop in an enzyme-substrate/product complex. Analyses of intermolecular interactions between the enzyme and this pseudo substrate/product along with functional analysis of Phe-66, Leu-97, and Phe-99 residues provide insights into the mechanism of substrate binding and catalysis in VHZ.