F0F1 ATP synthase activity is differently modulated by coronary reactive hyperemia before and after ischemic preconditioning in the goat

The amplitude of coronary reactive hyperemia (CRH), elicited by 15 s of ischemia, is reduced in hearts subjected to 5 min of ischemic preconditioning (IP). F0F1 ATP synthase activity and ATP concentration are also altered by IP. We hypothesized that F0F1 ATP synthase is differently modulated by the inhibitor protein IF(1) during CRH elicited before (CRHnp) and after (CRHprec) IP. Hemodynamic parameters were recorded in 10 anesthetized goats. Myocardial biopsies were obtained before IP (Cnp), during CRHnp, 4 and 6 min after the onset of CRHnp, after IP (Cprec), during CRHprec, and 4 min after CRHprec. F0F1 ATP synthase activity, ATP concentration, and ATP-to-ADP ratio (ATP/ADP) were determined. Compared with CRHnp, IP blunted CRHprec. F0F1 ATP synthase activity transiently increased during CRHnp, decreased 4 min after CRHnp, and returned to control 2 min later; it was lower after IP (Cprec) and did not change during and after CRHprec. All these changes in activity were modulated by IF1. During CRHnp, ATP concentration and ATP/ADP were reduced compared with Cnp and began to rise 6 min thereafter. During Cprec, both parameters were transiently reduced but increased during and after CRHprec. Hence, during CRHnp, F0F1 ATP synthase activity transiently increases and then decreases significantly. The short-lasting inhibition of the enzyme may explain why a few seconds of occlusion do not induce IP. After IP, F0F1 ATP synthase activity is blunted, and it is not affected by a subsequent 15 s of occlusion, which induces a blunted CRHprec. These results suggest that postischemic long-lasting inhibition of F0F1 ATP synthase activity may be a feature of the preconditioned heart. The increase in ATP concentration after preconditioning is in agreement with previous reports of reduced ATP hydrolysis by cytoplasmic ATPases.     

Conformational variation of surface class II MHC proteins during myeloid dendritic cell differentiation accompanies structural changes in lysosomal MIIC

Dendritic cells (DC), uniquely among APC, express an open/empty conformation of MHC class II (MHC-II) proteins (correctly folded molecules lacking bound peptides). Generation and trafficking of empty HLA-DR during DC differentiation are investigated here. HLA-DR did not fold as an empty molecule in the endoplasmic reticulum/trans-Golgi network, did not derived from MHC/Ii complexes trafficking to the cell surface, but was generated after invariant chain degradation within lysosomal-like MHC-II rich compartments (MIIC). In pre-DC, generated from monocytes cultured in the presence of GM-CSF, Lamp-1(+)MHC-II(+) compartments are predominantly electron dense and, in these cells, empty MHC-II molecules accounts for as much as 20% of total surface HLA-DR. In immature DC, generated in presence of GM-CSF and IL-4, empty HLA-DR reside in multilamellar MIIC, but are scarcely observed at the cell surface. Thus, the morphology/composition of lysosomal MIIC at different DC maturational stages appear important for surface egression or intracellular retention of empty HLA-DR. Ag loading can be achieved for the fraction of empty HLA-DR present in the "peptide-receptive" form. Finally, in vivo, APC-expressing surface empty HLA-DR were found in T cell areas of secondary lymphoid organs.     

Leptin promotes differentiation and survival of human dendritic cells and licenses them for Th1 priming

Leptin is an adipocyte-derived hormone/cytokine that links nutrition, metabolism, and immune homeostasis. Leptin is capable of modulating several immune responses. However, the effect of leptin on dendritic cells (DCs) has not yet been recognized. Because DCs are instrumental in the development of immune responses, in this study, we evaluated the impact of leptin on DC activation. We demonstrated the presence of leptin receptor in human immature and mature DCs both at mRNA and protein level and its capacity to transduce leptin signaling leading to STAT-3 phosphorylation. We found no consistent modulation of DC surface molecules known to be critical for their APC function in response to leptin. In contrast, we found that leptin induces rearrangement of actin microfilaments, leading to uropod and ruffle formation. At a functional level, leptin up-regulates the IL-1beta, IL-6, IL-12, TNF-alpha, and MIP-1alpha production. Coincident with this, leptin-treated DCs stimulate stronger heterologous T cell responses. Furthermore, we found that leptin down-regulates IL-10 production by DCs and drives naive T cell polarization toward Th1 phenotype. Finally, we found that leptin partly protects DCs from spontaneous and UVB-induced apoptosis. Consistent with the antiapoptotic effect of leptin, we observed the activation of NF-kappaB and a parallel up-regulation of bcl-2 and bcl-x(L) gene expression. These results provide new insights on the immunoregulatory function of leptin demonstrating its ability to improve DC functions and to promote DC survival. This is of relevance considering a potential application of leptin in immunotherapeutic approaches and its possible use as adjuvant in vaccination protocols.     

Absorption of albumin by the midgut of a lepidopteran larva

In the last decade, the study of peptide and protein absorption by the insect gut has received increasing attention because of the considerable impact this information may have on the development of new delivery strategies for insecticide macromolecules targeting haemocoelic receptors. Available experimental evidence in vivo suggests that, in insects, peptides and proteins can cross the intestinal barrier reaching the haemocoel, but the functional bases of this absorption pathway have not yet been thoroughly investigated. The current knowledge of the mechanisms involved in protein and polypeptide absorption in animals derives from the extensive studies performed in mammalian polarised epithelial cells, where the transcellular transport of proteins by transcytosis has been demonstrated. In this process, proteins are internalised at one pole of the cell and transported by cytoplasmic vesicular traffic to the opposite plasma membrane domain, where they are released with unchanged biological activity. Here we report data on albumin translocation across the isolated midgut of Bombyx mori caterpillars perfused in vitro. The functional properties of the transepithelial transport of this protein are described and, since absorption prevails over secretion, its lumen-to-haemolymph flux is characterised. Low-temperature incubations nearly abolish the transepithelial transport, while the peculiar physiological features of the larval midgut, i.e. the high lumen positive transepithelial voltage and the luminal alkaline pH, do not affect the flux. The obtained results indicate that albumin crosses B. mori larval midgut by transcytosis.     

The Vitamin D endocrine system of the gut--its possible role in colorectal cancer prevention

While Vitamin D insufficiency in the US and European population is rising, epidemiological studies suggest an inverse correlation between low serum levels of 25-hydroxyvitamin D(3) (25-OH-D(3)) and colorectal cancer incidence. The antimitotic, prodifferentiating and proapoptotic active metabolite 1alpha,25-dihydroxyvitamin D(3) (1,25-(OH)(2)-D(3)) is synthesized also by colonocytes, since these possess Vitamin D synthesizing (CYP27B1) and catabolic (CYP24) hydroxylases similar to the kidney. Early during colon tumor progression, expression of CYP27B1 and of the Vitamin D receptor increases, suggesting an autocrine/paracrine growth control in colon tissue as a physiological restriction against tumor progression. However, in human adenocarcinomas expression of the catabolic CYP24 is also enhanced when compared with adjacent normal mucosa. Therefore, to maintain colonic accumulation of 1,25-(OH)(2)-D(3) its catabolism needs to be restricted. Our studies in mice show that low nutritional calcium causes hyperproliferation of colon crypts and significant elevation of CYP24 expression, which can be completely abrogated by soy feeding. We suggest that phytoestrogens in soy, known to be estrogen receptor modulators, are responsible for decreased CYP24 expression. These results and our observation that 17beta-estradiol can elevate CYP27B1 expression in rectal tissue of postmenopausal women, may underlie the observed protective effect of estrogens against colorectal cancer in females.     

Bicyclic nucleoside inhibitors of Varicella-Zoster virus: the effect of branching in the p-alkylphenyl side chain

Further to the discovery of bicyclic furanopyrimidine nucleoside analogues (BCNAs) as potent anti-VZV agents, a branched series of this family of compounds was synthesised. The aim was to study the impact of the geometry and steric hindrance in the side chain as well as lipophilic role of this moiety on biological activity. The results showed a detrimental effect of branching on antiviral activity, with a different magnitude depending on the position of branching in the side chain. This study again showed the importance of this moiety for biological activity, as well as the limited efficacy of the ClogP value as a tool for predicting the potency of BCNAs, while suggesting an alternative rationale behind the design of future series.     

Synthesis and activity of 8-substituted benzo[c]quinolizin-3-ones as dual inhibitors of human 5alpha-reductases 1 and 2

Some potent dual inhibitors of 5alpha-reductases 1 and 2, based on the benzo[c]quinolizin-3-one structure and with IC(50) values ranging between 93 and 166nM for both isozymes, were found. The presence of the F atom on the ester moiety at the position 8 was crucial. This result can help in the design of other potent, dual inhibitors to be developed as drugs in the treatment of 5alpha-reductase related diseases.     

Insight into 2-phenylpyrazolo[1,5-a]pyrimidin-3-yl acetamides as peripheral benzodiazepine receptor ligands: synthesis, biological evaluation and 3D-QSAR investigation

The present paper reports the synthesis and binding studies of new 2-phenylpyrazolo[1,5-a]pyrimidin-3-yl acetamides as selective Peripheral Benzodiazepine Receptor (PBR) ligands. The variability of substituents at the 3-position was investigated and a 3D-QSAR model was proposed to evaluate the effect of different substitutions on the acetamide moiety. In addition, a subset of the novel compounds showing high affinity for PBR was tested for their ability to modulate the steroid biosynthesis in C6 glioma cells.     

Antimycobacterial compounds. Optimization of the BM 212 structure, the lead compound for a new pyrrole derivative class

Our work on antitubercular agents led to the identification of BM 212 as a lead compound among a series of pyrrole derivatives with good in vitro activity against mycobacteria and candidae. Further studies led us to synthesize additional pyrroles bearing the thiomorpholinomethyl moiety and different aryl substituents at N1 and C5. Some of them revealed very active, prompting us to design the new pyrrole derivatives 5-20 in the hope of increasing the activity and better understanding the influence of ortho halogens on the antimycobacterial activity. Microbiological data showed interesting in vitro activity toward Mycobacterium tuberculosis and atypical mycobacteria.