3,5 Diiodo-L-Thyronine (T2) Does Not Prevent Hepatic Steatosis or Insulin Resistance in Fat-Fed Sprague Dawley Rats

Thyroid hormone mimetics are alluring potential therapies for diseases like dyslipidemia, nonalcoholic fatty liver disease (NAFLD), and insulin resistance. Though diiodothyronines are thought inactive, pharmacologic treatment with 3,5- Diiodo-L-Thyronine (T2) reportedly reduces hepatic lipid content and improves glucose tolerance in fat-fed male rats. To test this, male Sprague Dawley rats fed a safflower-oil based high-fat diet were treated with T2 (0.25 mg/kg-d) or vehicle. Neither 10 nor 30 days of T2 treatment had an effect on weight, adiposity, plasma fatty acids, or hepatic steatosis. Insulin action was quantified in vivo by a hyperinsulinemic-euglycemic clamp. T2 did not alter fasting plasma glucose or insulin concentration. Basal endogenous glucose production (EGP) rate was unchanged. During the clamp, there was no difference in insulin stimulated whole body glucose disposal. Insulin suppressed EGP by 60% ± 10 in T2-treated rats as compared with 47% ± 4 suppression in the vehicle group (p = 0.32). This was associated with an improvement in hepatic insulin signaling; insulin stimulated Akt phosphorylation was ~2.5 fold greater in the T2-treated group as compared with the vehicle-treated group (p = 0.003). There was no change in expression of genes thought to mediate the effect of T2 on hepatic metabolism, including genes that regulate hepatic lipid oxidation (ppara, carnitine palmitoyltransferase 1a), genes that regulate hepatic fatty acid synthesis (srebp1c, acetyl coa carboxylase, fatty acid synthase), and genes involved in glycolysis and gluconeogenesis (L-pyruvate kinase, glucose 6 phosphatase). Therefore, in contrast with previous reports, in Sprague Dawley rats fed an unsaturated fat diet, T2 administration failed to improve NAFLD or whole body insulin sensitivity. Though there was a modest improvement in hepatic insulin signaling, this was not associated with significant differences in hepatic insulin action. Further study will be necessary before diiodothyronines can be considered an effective treatment for NAFLD and dyslipidemia.     

Natural isoquinoline alkaloids: binding aspects to functional proteins,serum albumins,hemoglobin, and lysozyme

The putative anticancer alkaloids berberine, palmatine, jatrorrhizine, and sanguinarine are known to bind to nucleic acids. To develop them as potential drugs for therapeutic use, their binding affinity to functional proteins and mode of transport in the circulatory system need to be clearly understood. Towards this, many studies on their binding aspects to proteins have been reported and a considerable amount of data, mostly of biophysical nature, exists in the literature. The importance of these natural isoquinoline alkaloids and the recent literature on their interaction phenomena with functional proteins, serum albumins, hemoglobin, and lysozyme are presented in this review.     

Antimicrobial activities of Gloriosa superba Linn (Colchicaceae) extracts

The methanol extract of the rhizomes of Gloriosa superba Linn (Colchicaceae) and its subsequent fractions in different solvent systems were screened for antibacterial and antifungal activities. Excellent antifungal sensitivity was expressed by the n-butanol fraction against Candida albicans and Candida glaberata (up to 90%) and against Trichophyton longifusus (78%) followed by the chloroform fraction against Microsporum canis (80%). In the antibacterial bioassay, the crude extract and subsequent fractions showed mild to moderate antibacterial activities. Chloroform fraction displayed highest antibacterial sensitivity against Staphylococcus aureous (88%) followed by the crude extract (59%). The total phenol content of the crude extract and fractions of the plant expressed no significant correlation with the antimicrobial activities.     

Current strategies and perspectives in detection and control of basal stem rot of oil palm

The rapid expansion of oil palm (OP) has led to its emergence as a commodity of strategic global importance. Palm oil is used extensively in food and as a precursor for biodiesel. The oil generates export earnings and bolsters the economy of many countries, particularly Indonesia and Malaysia. However, oil palms are prone to basal stem rot (BSR) caused by Ganoderma boninense which is the most threatening disease of OP. The current control measures for BSR management including cultural practices, mechanical and chemical treatment have not proved satisfactory. Alternative control measures to overcome the G. boninense problem are focused on the use of biological control agents and many potential bioagents were identified with little proven practical application. Planting OP varieties resistant to G. boninense could provide the ideal long-term solution to basal stem rot. The total resistance of palms to G. boninense has not yet been reported, and few examples of partial resistances have been observed. Importantly, basidiospores are now recognized as the method by which the disease is spread, and control methods require to be revaluated because of this phenomenon. Many methods developed to prevent the spread of the disease effectively are only tested at nursery levels and are only reported in national journals inhibiting the development of useful techniques globally. The initial procedures employed by the fungus to infect the OP require consideration in terms of the physiology of the growth of the fungus and its possible control. This review assesses critically the progress that has been made in BSR development and management in OP.     

An insight into functional genomics of transgenic lines of tomato cv Rio Grande harbouring yeast halotolerance genes

Tomato cv Rio Grande plants were transformed with yeast halotolerance genes (HAL I or HAL II) using pPM7HAL I or pJRM16HAL II, with p35GUSINT as control. Transformation efficiency varied in the three constructs, with highest transformation found with p35GUSINT. Final selection of the transgenic plants was made on the basis of PCR. Transgene integration and copy number were assessed by Southern hybridisation. The primary transformants were allowed to self-pollinate and the expected Mendelian ratios were studied in second-generation progeny. Five independent homozygous lines each of HAL I and HAL II, as well as the control, were characterised to study inter-transformant expression variability. The transformants showed considerable variability in expression of the respective genes, as shown by salt tolerance assays, chlorophyll content and peroxidase activity. The transgene expression in transgenic lines was analysed by semi-quantitative RT-PCR. In response to different salt concentrations, transgenic plants over-expressing HAL I and HAL II had significantly (α=0.05) better performance than the control This study presents the comparative responses of the three constructs under the same transformation conditions and suggests possible mechanisms governed by yeast HAL I and HAL II genes, which seem to work in a coordinated manner by relatively decreasing osmotic and oxidative shock at different rates. Our results suggest that the yeast HAL I increases K(+) /Na(+) selectivity and has a more functional role than HAL II in improving salt tolerance of the tomato cv Rio Grande grown in Pakistan.     

Interaction of the anticancer plant alkaloid sanguinarine with bovine serum albumin

Background

Interaction of the iminium and alkanolamine forms of sanguinarine with bovine serum albumin (BSA) was characterized by spectroscopic and calorimetric techniques.

Methodology/Principal Findings

Formation of strong complexes of BSA with both iminium and alkanolamine forms was revealed from fluorescence quenching of sanguinarine. Binding parameters calculated from Stern-Volmer quenching method revealed that the neutral alkanolamine had higher affinity to BSA compared to the charged iminium form. Specific binding distances of 3.37 and 2.38 nm between Trp 212 (donor) and iminium and alkanolamine forms (acceptor), respectively, were obtained from Forster resonance energy transfer studies. Competitive binding using the site markers warfarin and ibuprofen, having definite binding sites, demonstrated that both forms of sanguinarine bind to site I (subdomain IIA) on BSA. Sanguinarine binding alters protein conformation by reducing the α-helical organization and increasing the coiled structure, indicating a small but definitive partial unfolding of the protein. Thermodynamic parameters evaluated from isothermal titration calorimetry suggested that the binding was enthalpy driven for the iminium form but favoured by negative enthalpy and strong favourable entropy contributions for the alkanolamine form, revealing the involvement of different molecular forces in the complexation.

Conclusions/Significance

The results suggest that the neutral alkanolamine form binds to the protein more favourably compared to the charged iminium, in stark contrast to the reported DNA binding preference of sanguinarine.     

Use of G-Protein-Coupled and -Uncoupled CCR5 Receptors by CCR5 Inhibitor-Resistant and -Sensitive Human Immunodeficiency Virus Type 1 Variants

Small-molecule CCR5 inhibitors such as vicriviroc (VVC) and maraviroc (MVC) are allosteric modulators that impair HIV-1 entry by stabilizing a CCR5 conformation that the virus recognizes inefficiently. Viruses resistant to these compounds are able to bind the inhibitor-CCR5 complex while also interacting with the free coreceptor. CCR5 also interacts intracellularly with G proteins, as part of its signal transduction functions, and this process alters its conformation. Here we investigated whether the action of VVC against inhibitor-sensitive and -resistant viruses is affected by whether or not CCR5 is coupled to G proteins such as Gα_i. Treating CD4⁺ T cells with pertussis toxin to uncouple the Gα_i subunit from CCR5 increased the potency of VVC against the sensitive viruses and revealed that VVC-resistant viruses use the inhibitor-bound form of Gα_i-coupled CCR5 more efficiently than they use uncoupled CCR5. Supportive evidence was obtained by expressing a signaling-deficient CCR5 mutant with an impaired ability to bind to G proteins, as well as two constitutively active mutants that activate G proteins in the absence of external stimuli. The implication of these various studies is that the association of intracellular domains of CCR5 with the signaling machinery affects the conformation of the external and transmembrane domains and how they interact with small-molecule inhibitors of HIV-1 entry.     

Intersectionality,nationalisms, biocoloniality

The early twenty-first century is marked by new postcolonial nationalist ideologies and their indifference to modern histories of colonisation and the urgent need for anti-nationalist theories of racialised subjectification. I discuss the importance of work on ‘intersectionality’ and consider how some theoretical formations reproduce core elements of ‘common sense’ nationalisms such as universal, fixed racial categories, the gender binary and the idea of separate cultures. I then argue for a transdisciplinary theory of racialised subjectivity that I call ‘biocoloniality’.