The effects of ultraviolet radiation-B response on the morphology,ultrastructure, and photosynthetic pigments of Laurencia catarinensis and Palisada flagellifera (Ceramiales,Rhodophyta): a comparative study

The present work aims to compare the effects of ultraviolet radiation on the morphology, ultrastructure, and photosynthetic pigments of two species of Ceramiales: Laurencia catarinensis and Palisada flagellifera. To accomplish this, plants were cultivated and exposed to photosynthetically active radiation (PAR) at 60 μmol photons m^?2 s^?1 and PAR + ultraviolet B radiation (UVBR) at 0.35 W m^?2 at 3 h per day for 7 days. Subsequently, the apical segments of L. catarinensis and P. flagellifera were analyzed under light and transmission microscopy, and both growth rates and photosynthetic pigments were studied. After exposure to PAR + UVBR, L. catarinensis exhibited a high reduction in growth rate and loss of biomass, in addition to a reduction in the concentration of chlorophyll a when compared with treated plants of P. flagellifera. However, after 7 days of exposure to PAR + UVBR, both plants showed a reduction in phycobiliprotein content. Toluidine blue reaction did not show cell wall changes in treated species with PAR + UVBR. Staining of L. catarinensis and P. flagellifera with periodic acid–Schiff (PAS) after UVBR exposure showed an increase in the number of starch grains in both species. When observed by transmission electron microscopy, treated samples of both species also showed disrupted thylakoids of the chloroplasts and an increased number of plastoglobuli. Based on this line of evidence, the present study demonstrates that ultraviolet radiation negatively affects the intertidal macroalgae L. catarinensis and P. flagellifera.     

Nicotinamide Phosphoribosyltransferase Promotes Epithelial-to-Mesenchymal Transition as a Soluble Factor Independent of Its Enzymatic Activity

Boosting NAD⁺ biosynthesis with NAD⁺ intermediates has been proposed as a strategy for preventing and treating age-associated diseases, including cancer. However, concerns in this area were raised by observations that nicotinamide phosphoribosyltransferase (NAMPT), a key enzyme in mammalian NAD⁺ biosynthesis, is frequently up-regulated in human malignancies, including breast cancer, suggesting possible protumorigenic effects for this protein. We addressed this issue by studying NAMPT expression and function in human breast cancer in vivo and in vitro. Our data indicate that high NAMPT levels are associated with aggressive pathological and molecular features, such as estrogen receptor negativity as well as HER2-enriched and basal-like PAM50 phenotypes. Consistent with these findings, we found that NAMPT overexpression in mammary epithelial cells induced epithelial-to-mesenchymal transition, a morphological and functional switch that confers cancer cells an increased metastatic potential. However, importantly, NAMPT-induced epithelial-to-mesenchymal transition was found to be independent of NAMPT enzymatic activity and of the NAMPT product nicotinamide mononucleotide. Instead, it was mediated by secreted NAMPT through its ability to activate the TGFβ signaling pathway via increased TGFβ1 production. These findings have implications for the design of therapeutic strategies exploiting NAD⁺ biosynthesis via NAMPT in aging and cancer and also suggest the potential of anticancer agents designed to specifically neutralize extracellular NAMPT. Notably, because high levels of circulating NAMPT are found in obese and diabetic patients, our data could also explain the increased predisposition to cancer of these subjects.     

Safety and tolerability of sitagliptin in clinical studies: a pooled analysis of data from 10,246 patients with type 2 diabetes

Background

In a previous pooled analysis of 12 double-blind clinical studies that included data on 6,139 patients with type 2 diabetes, treatment with sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, was shown to be generally well tolerated compared with treatment with control agents. As clinical development of sitagliptin continues, additional studies have been completed, and more patients have been exposed to sitagliptin. The purpose of the present analysis is to update the safety and tolerability assessment of sitagliptin by pooling data from 19 double-blind clinical studies.

Methods

The present analysis included data from 10,246 patients with type 2 diabetes who received either sitagliptin 100 mg/day (N = 5,429; sitagliptin group) or a comparator agent (placebo or an active comparator) (N = 4,817; non-exposed group). The 19 studies from which this pooled population was drawn represent the double-blind, randomized studies that included patients treated with the usual clinical dose of sitagliptin (100 mg/day) for between 12 weeks and 2 years and for which results were available as of July 2009. These 19 studies assessed sitagliptin taken as monotherapy, initial combination therapy with metformin or pioglitazone, or as add-on combination therapy with other antihyperglycemic agents (metformin, pioglitazone, a sulfonylurea ± metformin, insulin ± metformin, or rosiglitazone + metformin). Patients in the non-exposed group were taking placebo, metformin, pioglitazone, a sulfonylurea ± metformin, insulin ± metformin, or rosiglitazone + metformin. The analysis used patient-level data from each study to evaluate between-group differences in the exposure-adjusted incidence rates of adverse events.

Results

Summary measures of overall adverse events were similar in the sitagliptin and non-exposed groups, except for an increased incidence of drug-related adverse events in the non-exposed group. Incidence rates of specific adverse events were also generally similar between the two groups, except for increased incidence rates of hypoglycemia, related to the greater use of a sulfonylurea, and diarrhea, related to the greater use of metformin, in the non-exposed group and constipation in the sitagliptin group. Treatment with sitagliptin was not associated with an increased risk of major adverse cardiovascular events.

Conclusions

In this updated pooled safety analysis of data from 10,246 patients with type 2 diabetes, sitagliptin 100 mg/day was generally well tolerated in clinical trials of up to 2 years in duration.     

Structural investigation of bilayers formed by 1-palmitoyl-2-oleoylphosphatidylnucleosides

Bilayers of palmitoyl-oleoylphosphatidylnucleoside derivatives (1-palmitoyl-2-oleoyl-phosphatidyl-adenosine and 1-palmitoyl-2-oleoyl-phosphatidyl-uridine) were synthesized and investigated in the low-water content regime by a combination of neutron diffraction and Fourier transform infrared linear dichroism (LD-FTIR). Attention was focused on the modulation of structural properties operated by the presence of nucleic acid bases (either adenosine or uridine, a purine and a pyrimidine that are complementary in RNA). Base substitution causes major differences in phase behavior of the phospholipids, i.e., water sorption from a controlled humidity atmosphere and smectic periodicity. The profile of scattering length density can be inferred from five diffraction orders for 1-palmitoyl-2-oleoyl-phosphatidyl-uridine lamellar phase. 1-Palmitoyl-2-oleoyl-phosphatidyl-adenosine is characterized by lower and less ready hydration, giving rise to a powder-like sample. A linear dichroism FTIR investigation on the same lamellar phases was undertaken with the purpose of gathering details at the submolecular level on different portions of the molecule. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers were also investigated with the same technique for the sake of comparison. Besides a confirmation of the diffraction data interpretation, FTIR has provided evidence that the same chemical groups at the bilayer interface (namely the sugar-phosphate) have a different orientation depending on whether the base is a purine or a pyrimidine. A very simple geometrical optimization agrees with this observation. This indicates that a different pattern of base interaction is operating in the two cases and that base substitution acts as a modulator of the phase properties.     

The crystal structure of the primary Ca2+ sensor of the Na+/Ca2+ exchanger reveals a novel Ca2+ binding motif

The Na+/Ca2+ exchanger is a plasma membrane protein that regulates intracellular Ca2+ levels in cardiac myocytes. Transport activity is governed by Ca2+, and the primary Ca2+ sensor (CBD1) is located in a large cytoplasmic loop connecting two transmembrane helices. The binding of Ca2+ to the CBD1 sensory domain results in conformational changes that stimulate the exchanger to extrude Ca2+. Here, we present a crystal structure of CBD1 at 2.5A resolution, which reveals a novel Ca2+ binding site consisting of four Ca2+ ions arranged in a tight planar cluster. This intricate coordination pattern for a Ca2+ binding cluster is indicative of a highly sensitive Ca2+ sensor and may represent a general platform for Ca2+ sensing.     

Protein folding and aggregation: two sides of the same coin in the condensation of proteins revealed by pressure studies

Hydrostatic pressure can be considered as "thermodynamic tweezers" to approach the protein folding problem and to study the cases when folding goes wrong leading to the protein folding disorders. The main outcome of the use of high pressure in this field is the stabilization of folding intermediates such as partially folded conformations, thus allowing us to characterize their structural properties. Because partially folded intermediates are usually at the intersection between productive and off-pathway folding, they may give rise to misfolded proteins, aggregates and amyloids that are involved in many neurodegenerative diseases, such as transmissible spongiform encephalopathies, Alzheimer's disease, Parkinson's disease and Huntington's disease. Of particular interest is the use of hydrostatic pressure to unveil the structural transitions in prion conversion and to populate possible intermediates in the folding/unfolding pathway of the prion protein. The main hypothesis for prion diseases proposes that the cellular protein (PrP(C)) can be altered into a misfolded, beta-sheet-rich isoform, the PrP(Sc) (from scrapie). It has been demonstrated that hydrostatic pressure affects the balance between the different prion species. The last findings on the application of high pressure on amyloidogenic proteins will be discussed here as regards to their energetic and volumetric properties. The use of high pressure promises to contribute to the identification of the underlying mechanisms of these neurodegenerative diseases and to develop new therapeutic approaches.     

Gel-free analysis of the human brain proteome: application of liquid chromatography and mass spectrometry on biopsy and autopsy samples

This paper reports on the findings of the Biomedical Research Institute, as one of the participants in the pilot study of the HUPO Brain Proteome Project. A biopsy and autopsy study sample derived from human brain was distributed among the participants for proteomic analysis. In our laboratory, attention was focused on protein identification using the bottom-up shotgun approach. Protein extracts derived from both samples were trypsinized and analyzed separately by 2-D LC and MS. In a complementary approach, the tryptic digests were analyzed directly by LC-ESI-MS/MS and gas-phase fractionation in the mass spectrometer. Taken together, both proteomic approaches in combination with a stringent evaluation process, resulted in the confident identification of 209 proteins in the human brain samples under investigation.     

p16(INK4A) immunohistochemical overexpression in premalignant and malignant oral lesions infected with human papillomavirus.

Human papillomavirus (HPV) is believed to promote the oncogenic process, and the correlation between viral oncoproteins and dysfunction of p16(INK4A) tumor suppressor protein in oral lesions is controversial. To test the hypothesis that anogenital HPV types participate in disruption of the regulation of p16(INK4A) suppressor protein in oral lesions, we analyzed 46 oral biopsy specimens for the presence of HPV 6/11 and 16/18 by in situ hybridization (ISH) and for p16(INK4A) expression by immunohistochemistry (IHC). Eighteen (39%) of the 46 oral lesions were HPV-positive and 28 (61%) were HPV-negative. HPV 6/11 DNA was found in 5 (11%) and HPV 16/18 in 13 (28%) of 46 biopsies. Nine of the 18 HPV-positive oral lesions (50%), assessed by catalyzed signal amplification coupled to ISH (CSA-ISH), gave high-intensity p16(INK4A) immunostaining. Focal and diffuse patterns were observed in 11/13 (77%) lesions with HPV 16/18, focal immunopositivity in 3/5 (80%) with HPV 6/11, and negative or sporadic p16-labeling in 18/28 (64%) without the presence of HPV DNA. These results showed a strong association between overexpression of p16 protein and malignant oral lesions, mainly those infected by HPV 16/18. We can conclude that high-risk HPV types are associated with p16 overexpression, and p16 may serve as a biomarker in oral cancer related to high-risk HPV infection.     

Sedimentological history of Bryant Canyon area, northwest Gulf of Mexico, during the last 135 kyr (Marine Isotope Stages 1-6): A proxy record of Mississippi River discharge

Bryant and Eastern Canyons are located in northwest Gulf of Mexico, and are characterized by a complex sedimentological history related to glacioeustatic cycles, river discharges, and interactions between depositional and halokinetic processes. This study is based on detailed sedimentological analysis from forty-eight long cores from these two canyons. This paper determines the evolutionary history of the canyons and assesses the response of sedimentary processes to morphological, climatic, hydrological, and sea-level changes.During the last glaciation, the upper and middle continental slope was supplied with sediments by low density turbidity currents derived from the depositional segregation (deposition of the coarsest material in the most proximal locations) of large turbidity currents initiated on the outer shelf. The lower continental slope was supplied with sediment by westward flowing bottom currents, originated from the entrainment of the most diluted wash-load and tails of turbidity currents from the Mississippi Fan.Bryant and Eastern Canyon systems were active during the penultimate glaciation, Marine Isotope Stage (MIS) 6, and were supplied with sediments by an ancestral shelf-margin Mississippi River delta. Gravity flows transported enormous amounts of sediment to the continental slope and abyssal plain of the northwest Gulf of Mexico. The sea-level rise at MIS 5 led to confinement of river-sourced sediments to the widespread continental shelf of the northwest Gulf of Mexico, and consequently to the cessation of gravity flows. During the first 40 kyr of MIS 5, salt diapirs transformed the canyons into a network of intraslope basins.The sea level dropped to the mid-shelf during MIS 3 and 4, but never reached the shelf-break, and therefore, river-sourced sediments remained largely confined to the shelf. However, seaward sediment transportation was achieved occasionally through turbidity currents related to sediment failures, storms, and high-river discharges. Four high river discharge events have been identified during this period. The first three were centred at 37, 45, and 53 cal ka BP. The last high river discharge occurred at the end of MIS 3 (29.4-33.2 cal ka BP), and resulted in the deposition of closely-spaced, mud turbidites over the entire continental slope. The Laurentide Ice Sheet (LIS) was restricted north of the upper Mississippi River valley during 60 to ∼ 30 cal ka BP and therefore, the high river discharge events are interpreted as melt-water events, related to brief southward advancements of the LIS, which resulted in the flooding of Mississippi River. The extensive lowering of sea level during the last glacial maximum (MIS 2) resulted in the almost direct discharge of Mississippi River sediments to the upper continental slope leading to the development of abundant turbidity currents. Eleven wet-dry cycles during this period are defined; they probably originated from episodic subglacial melt-water floods, released from southern parts of the LIS.The last deglaciation event is characterized by the development of a major melt water event at 16.5-13 cal ka BP that resulted in the deposition of distinct, organic-rich sediments. At about 13 cal ka BP, the melt water discharges of the LIS in North America switched from the Mississippi River to either the St. Lawrence or Mackenzie River valleys, causing the domination of hemipelagic sedimentation on the continental slope of the northwest Gulf of Mexico. Isotopic data indicate that melt-water discharges returned to the Mississippi River Valley at ∼ 11.4 cal ka BP. The absence of any sedimentological indication on the continental slope of the northwest Gulf of Mexico of the return of the melt-water discharges to the Mississippi River is attributed to the confinement of river-sourced sediments on the continental shelf due to the rise of the sea level.