Defining the disulfide bonds of insulin-like growth factor-binding protein-5 by tandem mass spectrometry with electron transfer dissociation and collision-induced dissociation

The six high-affinity insulin-like growth factor-binding proteins (IGFBPs) comprise a conserved family of secreted molecules that modulate IGF actions by regulating their half-life and access to signaling receptors, and also exert biological effects that are independent of IGF binding. IGFBPs are composed of cysteine-rich amino- (N-) and carboxyl- (C-) terminal domains, along with a cysteine-poor central linker segment. IGFBP-5 is the most conserved IGFBP, and contains 18 cysteines, but only 2 of 9 putative disulfide bonds have been mapped to date. Using a mass spectrometry (MS)-based strategy combining sequential electron transfer dissociation (ETD) and collision-induced dissociation (CID) steps, in which ETD fragmentation preferentially induces cleavage of disulfide bonds, and CID provides exact disulfide linkage assignments between liberated peptides, we now have definitively mapped 5 disulfide bonds in IGFBP-5. In addition, in conjunction with ab initio molecular modeling we are able to assign the other 4 disulfide linkages to within a GCGCCXXC motif that is conserved in five IGFBPs. Because of the nature of ETD fragmentation MS experiments were performed without chemical reduction of IGFBP-5. Our results not only establish a disulfide bond map of IGFBP-5 but also define a general approach that takes advantage of the specificity of ETD and the scalability of tandem MS, and the predictive power of ab initio molecular modeling to characterize unknown disulfide linkages in proteins.

Novel biomarker candidates to predict hepatic fibrosis in hepatitis C identified by serum proteomics

BACKGROUND

Liver biopsy remains the gold standard to assess hepatic fibrosis. It is desirable to predict hepatic fibrosis without the need for invasive liver biopsy. Proteomic techniques allow unbiased assessment of proteins and might be useful to identify proteins related to hepatic fibrosis.

AIMS

We utilized two different proteomic methods to identify serum proteins as candidate biomarkers to predict hepatic fibrosis stage in patients with chronic hepatitis C virus (HCV) infection.

METHODS

Serum was obtained from 24 people with chronic HCV at time of liver biopsy and from 6 normals. Liver biopsy fibrosis was staged 1-4 (Batts-Ludwig). Pooled serum samples (six in each of four fibrosis groups and controls) were analyzed with 4- and 8-plex isobaric tags for relative and absolute quantitation (iTRAQ), determining protein identification (ID) and ratios of relative protein abundance. Nonpooled samples were analyzed with two-dimensional (2-D) gels and difference in gel electrophoresis (DIGE) comparing different samples on the same gel and across gels. Spots varying among groups were measured with densitometry, excised, digested, and submitted for tandem mass spectrometry (MS/MS) protein ID.

RESULTS

iTRAQ identified 305 proteins (minimum 99% ID confidence); 66 were increased or decreased compared with controls. Some proteins were increased or decreased for specific fibrosis scores. From 704 DIGE protein spots, 66 were chosen, 41 excised, and 135 proteins identified, since one gel spot often identified more than one protein.

CONCLUSIONS

Both proteomic methods identified two proteins as biomarker candidates for predicting hepatic fibrosis: complement C4-A and inter-alpha-trypsin inhibitor heavy chain H4.

Emergency pancreaticoduodenectomy in a patient with an ampullary adenocarcinoma associated with severe acute pancreatitis: a case report

Emergency pancreatico-duodenectomy is an infrequent surgical procedure. Herein, it is reported the case of a 58-year old man with ampullary carcinoma revealed by acute necrotizing pancreatitis. Due to clinical features, an emergency two-step pancreatico-duodenectomy was performed, accomplished by pancreatic and peripancreatic necrosectomy. The distal remnant pancreas was drained as an external pancreatic fistula. A time later, after complete remittance of local inflammation, the pancreas was anastomosed to the jejunum. The postoperative outcome was uneventful, the patient being disease-free at more than 5 years after surgery. Thus, pancreatico-duodenectomy is a feasible and safe operation when performed in tertiary hepato-bilio-pancreatic centers, in selected cases.

Nascent proteomes of ischemic-injured and ischemic-tolerant neuronal cells

In a recent study on ischemic rodent brains, we quantitatively characterised and compared brain proteomes under ischemic-preconditioned or injured or tolerant conditions. We discovered an enriched presence of repressive transcriptional regulator proteins with essential roles as epigenetic regulators in ischemic-tolerant brains (Stapels et al., 2010). We further showed their robust, dynamic and differential changes under different ischemic conditions in brains and in cultured neuronal cells. In the present work, using neuronal cell cultures, we aimed to characterise the nascent proteome, the proteome that presents early when the cells receive an ischemic insult. These would be the proteomic changes of newly synthesised proteins. Identification of effectors of this phase of response to ischemia bears the best promise of identifying therapeutic targets for treating acute stroke when patients present to hospital. We compared these nascent proteomes across different ischemic conditions using bioinformatic tools.

Synthesis-Morphology-Mechanical Properties Relationships Of Polymer-Silica Nanocomposite Hybrid Materials

Two types of polymer-silica nanocomposites have been prepared by undergoing free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) either in the presence of HEMA-functionalized SiO2 nanoparticles (Type 1) or during the simultaneous in situ growing of the silica phase through the acid-catalyzed sol-gel polymerization of tetraethoxysilane (TEOS) (Type 2). Relationships between synthesis, morphology and mechanical properties are discussed mainly on the basis of solid state 29Si nuclear magnetic resonance spectroscopy (NMR), transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), and dynamic mechanical analysis (DMA).

O-glicosylation alterations of proteins in gastric carcinoma

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Background: The expression of immature forms of carbohydrates could help to better understand the biological behavior of gastric cancer.

Methods: From a universe of 50 patients with gastric or gastroesophageal junction carcinoma submitted to surgical treatment between January and October 2009, in our department, 36 out of 38 carcinomas ressected during this period, were selected for a tumor tissue immunohistochemical study of the simple mucin-type carbohydrate antigens (Tn, STn, T and ST) and the Lewis carbohydrate antigens (SLea and SLex). Several clinico-pathological parameters were evaluated according to the expression pattern of the antigens studied.

Results: The ressected gastric carcinomas presented a high incidence of tissue expression of the simple mucin-type and the Lewis carbohydrate antigens, with all cases presenting expression of at least 2 of the antigens and two thirds the expression of 4 or 5. The correlation between the simple mucin-type carbohydrate antigens was high, just as the same as with the Lewis carbohydrate antigens. The analysis of the clinico-pathological profile of gastric carcinomas according to the expression of these antigens revealed the following associations: Tn with venous invasion and perineural invasion; STn with tumor location and macroscopic form; T with age, gender, tumor dimensions and location; ST with macroscopic form and WHO classification; SLea and SLex with the tumor dimensions. Staging of the tumors also revealed associations with the expressions of these antigens: Tn with serosal invasion, lymph node metastases and stage; STn with lymph node ratio; SLea with serosal invasion and lymph node metastases; SLex with depth wall invasion, lymph node metastases and stage. The antigens T e ST did not reveal differences in the expression pattern according to staging.

Conclusions: O-glicosylation alterations of proteins are related with gastric carcinoma, not only their incidence is high but they can also be linked with various clinico-pathological characteristics. The knowledge obtained from this study might serve as a starting point for future investigations taking into account the identification of new biomarkers based on glicosylation alterations of proteins.

No significant financial relationships to disclose.

Elevated copper remodels hepatic RNA processing machinery in the mouse model of Wilson's disease

Copper is essential to mammalian physiology, and its homeostasis is tightly regulated. In humans, genetic defects in copper excretion result in copper overload and Wilson's disease (WD). Previous studies on the mouse model for WD (Atp7b(-)(/-)) revealed copper accumulation in hepatic nuclei and specific changes in mRNA profile prior to the onset of pathology. To find a molecular link between nuclear copper elevation and changes in hepatic transcriptome, we utilized quantitative ionomic and proteomic approaches. X-ray fluorescence and inductively coupled plasma mass spectrometry analysis indicate that copper in the Atp7b(-/-) nucleus, while highly elevated, does not markedly alter nuclear ion content. Widespread protein oxidation is also not observed, although the glutathione reductase SelH is upregulated, likely to maintain redox balance. We further demonstrate that accumulating copper affects the abundance and/or modification of a distinct subset of nuclear proteins. These proteins populate pathways that are most significantly associated with RNA processing. An alteration in splicing pattern was observed for hnRNP A2/B1, itself the RNA shuttling factor and spliceosome component. Analysis of hnRNP A2/B1 mRNA and protein revealed an increased retention of exon 2 and a selective 2-fold upregulation of a corresponding protein splice variant. Mass spectrometry measurements suggest that the nucleocytoplasmic distribution of RNA binding proteins, including hnRNP A2/B1, is altered in the Atp7b(-/-) liver. We conclude that remodeling of the RNA processing machinery is an important component of cell response to elevated copper that may guide pathology development in the early stages of WD.

Remodeling of protein and mRNA expression in Leishmania mexicana induced by deletion of glucose transporter genes

Glucose is a major nutrient in the insect vector stage of Leishmania parasites. Glucose transporter null mutants of Leishmania mexicana exhibit profound phenotypic changes in both insect stage promastigotes and mammalian host stage amastigotes that reside within phagolysosomes of host macrophages. Some of these phenotypic changes could be either mediated or attenuated by changes in gene expression that accompany deletion of the glucose transporter genes. To search for changes in protein expression, the profile of proteins detected on two-dimensional gels was compared for wild type and glucose transporter null mutant promastigotes. A total of 50 spots whose intensities changed significantly and consistently in multiple experiments were detected, suggesting that a cohort of proteins is altered in expression levels in the null mutant parasites. Following identification of proteins by mass spectrometry, 3 such regulated proteins were chosen for more detailed analysis: mitochondrial aldehyde dehydrogenase, ribokinase, and hexokinase. Immunoblots employing antisera against these enzymes confirmed that their levels were upregulated, both in glucose transporter null mutants and in wild type parasites starved for glucose. Quantitative reverse transcriptase PCR (qRT-PCR) revealed that the levels of mRNAs encoding these enzymes were also enhanced. Global expression profiling using microarrays revealed a limited number of additional changes, although the sensitivity of the microarrays to detect modest changes in amplitude was less than that of two-dimensional gels. Hence, there is likely to be a network of proteins whose expression levels are altered by genetic ablation of glucose transporters, and much of this regulation may be reflected by changes in the levels of the cognate mRNAs. Some of these changes in protein expression may reflect an adaptive response of the parasites to limitation of glucose.

Nucleotide oligomerization domain-2 interacts with 2'-5'-oligoadenylate synthetase type 2 and enhances RNase-L function in THP-1 cells

Nucleotide-binding and oligomerization domain-2 (NOD2) is an intracellular protein involved in innate immunity and linked to chronic inflammatory diseases in humans. Further characterization of the full spectrum of proteins capable of binding to NOD2 may provide new insights into its normal functioning as well as the mechanisms by which mutated forms cause disease. Using a proteomics approach to study human THP-1 cells, we have identified 2'-5'-oligoadenylate synthetase type 2 (OAS2), a dsRNA binding protein involved in the pathway that activates RNase-L, as a new binding partner for NOD2. The interaction was confirmed using over-expression of OAS2 and NOD2 in HEK cells. Further confirmation was obtained by detecting NOD2 in immunoprecipitates of endogenous OAS2 in THP-1 cells. Finally, over-expression of NOD2 in THP-1 cells led to enhanced RNase-L activity in cells treated with poly(I:C), a mimic of double-stranded RNA virus infection. These data indicate connectivity in pathways involved in innate immunity to bacteria and viruses and suggest a regulatory role whereby NOD2 enhances the function of RNase-L.

How do UK medical graduates rate their knowledge and skills in sexual health and HIV medicine? A national survey

The objectives of this study are to determine self-assessed knowledge and skills in sexual health and HIV medicine in preregistration house officers and to explore undergraduate experiences of teaching and assessment in these subjects prior to the launch of National Core Learning Outcomes in Sexual and Reproductive Health and HIV. The study was designed as a postal questionnaire survey. The participants were all UK medical graduates of August 2004. The response rate 1737/4746 (36%). The main outcome measures were Doctors' views on their preparedness to manage patients with sexual health and HIV-related problems. Since graduation, 90% of respondents had seen at least one patient with a sexually transmitted infection or HIV-related issue. Seventy-six percent felt confident to take a sexual history. In all, 63% and 53% felt competent in male and female genital examination, respectively. Forty-three percent felt they could conduct an appropriate HIV pretest discussion and 59% felt they could recognize clinical indicators suggestive of HIV. Seventy-eight percent had been formally assessed in sexual health and 55% in HIV medicine. Increased confidence in sexual history taking, HIV pretest discussion and recognition of HIV indicators was associated with a longer duration of teaching and formal examination. In conclusion, although the proportion of recent graduates confident in sexual history taking is encouraging, their lack of skill in discussing HIV testing, risk assessment and recognition of possible HIV presentations must be addressed. Integration of National Core Learning Outcomes into all undergraduate curricula is a key step in reducing inconsistencies in undergraduate training.

[Glomus tumor with diplopia]

This paper highlights the case of a 46-year-old female patient who seeks ophthalmic medical advice for her complaint about double vision on right gaze. Patient's medical history reveals several symptoms like headaches, progressive hearing loss on right side and dysphonia for which all investigations proved irrelevant. Thourough clinical examination, lab exams and imaging techniques revealed the cause for this symptoms i.e. glomic tumour with middle ear extention. We find this case to be exceptional as ocular symptoms led to the diagnose of a non-ocular serious, possible life threatening condition, bearing in mind that previously occured non-ocular symptoms couldn't elucidate the cause.

[Recurrent benign cystic peritoneal mesothelioma]

The benign cystic peritoneal mesothelioma (BCPM) is a rare neoplasm affecting mainly females at reproductive age. The natural history and physiopathology of the BCPM are not entirely known. It is mainly characterized by the lack of malignant elements, no tendency to metastasis and by a pervasive tendency to generate local recurrences after surgical removal. The clinical manifestations are insidious, uncharacteristic; the benign cystic peritoneal mesothelioma is often discovered during a surgical procedure addressing another condition. Imaging tests can raise the suspicion of BCPM but the diagnostic can only be confirmed by histopathological examination corroborated with an immunohistochemical analysis. There are no long term studies dictating a single therapeutic attitude but a high risk of local recurrences and the possibility of transformation into malignant mesothelioma have lead to the current tendency towards an aggressive treatment of the tumor. We present the case of a recurrent benign cystic peritoneal mesothelioma in a 40 years old female patient, emphasizing the therapeutic approach and the role of radical surgery in the treatment of BPCM.

Collagens, stromal cell-derived factor-1alpha and basic fibroblast growth factor increase cancer cell invasiveness in a hyaluronan hydrogel

OBJECTIVE

Beyond to control of cell migration, differentiation and proliferation, the extracellular matrix (ECM) also contributes to invasiveness of human cancers. As the roles of hyaluronan (HA) and collagens in this process are still controversial, we have investigated their involvement in cancer pathogenesis.

MATERIALS AND METHODS

With this aim in view, we developed a three-dimensional matrix, as reticulate HA hydrogel alone or coated with different collagens, in which cells could invade and grow.

RESULTS

We show that cancer cells, which were non-invasive in a single HA hydrogel, acquired this capacity in the concomitant presence of type I or III collagens. Both types of ECM compound, HA and collagens, possess the capacity to stimulate production of metalloprotease-2, recognized otherwise as a factor for poor cancer prognosis. HA-provoked cellular invasiveness resulted from CD44-mediated increase in cytosolic [Ca2+] and its subsequent hydrolysis due to ADAM (a disintegrin and metalloprotease) proteolytic activity. Interestingly, this mechanism seemed to be absent in non-invasive cancer cell lines.

CONCLUSION

Furthermore, using basic fibroblast growth factor and stromal cell-derived factor-1alpha, we also show that this three-dimensional reticulate matrix may be considered as a valuable model to study chemokinetic and chemotactic potentials of factors present in tumour stroma.