Cancer risk among parous women following assisted reproductive technology.

STUDY QUESTION: Do women who give birth after assisted reproductive technology (ART) have an increased risk of cancer compared with women who give birth without ART? SUMMARY ANSWER: Without correction, the results indicate an increase in overall cancer risk, as well as a 50% increase in risk of CNS cancer for women giving birth after ART, however the results were not significant after correcting for multiple analyses. WHAT IS KNOWN ALREADY: Studies regarding the effects of hormonal treatments involved with ART on subsequent cancer risk have provided inconsistent results, and it has also been suggested that infertility itself could be a contributory factor. STUDY DESIGN, SIZE, DURATION: A population-based cohort consisting of all women registered in the Medical Birth Registry of Norway as having given birth between 1 January 1984 and 31 December 2010 was assembled (n = 812 986). Cancers were identified by linkage to the Cancer Registry of Norway. Study subjects were followed from start of first pregnancy during the observational period until the first cancer, death, emigration, or 31 December 2010. PARTICIPANTS/MATERIALS, SETTING, METHODS: Of the total study population (n = 806 248), 16 525 gave birth to a child following ART. Cox regression analysis computed hazard ratios (HR) and 95% confidence intervals (CI) comparing cancer risk between ART women and non-ART women; for overall cancer, and for cervical, ovarian, uterine, central nervous system (CNS), colorectal and thyroid cancers, and for malignant melanoma. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 22 282 cohort members were diagnosed with cancer, of which 338 were ART women and 21 944 non-ART women. The results showed an elevated risk in one out of seven sites for ART women. The HR for cancer of the CNS was 1.50 (95% CI 1.03- 2.18), and among those specifically subjected to IVF (without ICSI) the HR was 1.83 (95% CI 1.22-2.73). Analysis of risk of overall cancer gave an HR of 1.16 (95% CI 1.04-1.29). Among those who had delivered only one child by the end of follow-up, the HR for ovarian cancer was 2.00 (95% CI 1.08-3.65), and for those nulliparous at entry the HR was 1.80 (95% CI 1.04-3.11). However, all findings became non-significant after correcting for multiple analyses. LIMITATIONS, REASONS FOR CAUTION: The results of elevated risk of overall cancer and CNS cancer lost significance when adjusting for multiple analyses, implying an important limitation of the study. The follow-up time was relatively short, especially for ART women. In addition, as the cohort was relatively young, there were few incident cancers, especially for some rarer cancer forms, such as uterine cancer. Risk assessments according to different causes of infertility could not be done. WIDER IMPLICATIONS OF THE FINDINGS: In light of the findings in the present study, further studies should be made on risk of CNS and ovarian cancer, and continued monitoring of all those treated with ART is encouraged. Our findings may only be generalizable to women who give birth after ART, and the risk for women who remain nulliparous after ART remains to be assessed. STUDY FUNDING/COMPETING INTEREST: The study was funded by the Norwegian National Advisory Unit on Women's Health. All authors claim no competing interests.

Treatment strategies and overall survival for incurable metastatic colorectal cancer - A EURECCA international comparison including 21,196 patients from the Netherlands and Norway.

BACKGROUND: The potential benefit of surgery of the primary tumour in patients with asymptomatic metastatic colorectal cancer is debated. This EURECCA international comparison analyses treatment strategies and overall survival in the Netherlands and Norway in patients with incurable metastatic colorectal cancer. METHODS: National cohorts (2007-2013) from the Netherlands and Norway including all patients with synchronous metastatic colorectal cancer were compared on treatment strategy and overall survival. Using country as an instrumental variable, we assessed the effect of different treatment strategies on mortality in the first year. RESULTS: Of 21,196 patients (16,144 Dutch and 5052 Norwegian), 38.6% Dutch and 51.5% (p < 0.001) Norwegian patients underwent resection of the primary tumour. In the Netherlands, 58.2% received chemotherapy compared with 21.4% in Norway. Radiotherapy was given in 9.5% of Dutch patients and 7.2% of Norwegian patients. Using the Netherlands as reference, the adjusted HR for overall survival was 0.96 (95% CI 0.93-0.99; p = 0.024). Instrumental variable analysis showed an adjusted OR of 1.00 (95% CI 0.99-1.02; p = 0.741). CONCLUSIONS: Treatment strategies varied significantly between the Netherlands and Norway, with more surgery and less radiotherapy in Norway. Adjusted overall survival was better in Norway for all patients and patients <75 years, but not for patients ≥75 years. Instrumental variable analysis showed no benefit in one-year mortality for a treatment strategy with a higher proportion of surgery and a lower proportion of radiotherapy. Our findings emphasise the need for further research to select patients with incurable metastatic colorectal cancer for different treatment options.

The three-dimensional structure of mammalian ribonucleotide reductase protein R2 reveals a more-accessible iron-radical site than Escherichia coli R2.

The three-dimensional structure of mouse ribonucleotide reductase R2 has been determined at 2.3 A resolution using molecular replacement and refined to an R-value of 19.1% (Rfree = 25%) with good stereo-chemistry. The overall tertiary structure architecture of mouse R2 is similar to that from Escherichia coli R2. However, several important structural differences are observed. Unlike the E. coli protein, the mouse dimer is completely devoid of beta-strands. The sequences differ significantly between the mouse and E. coli R2s, but there is high sequence identity among the eukaryotic R2 proteins, and the identities are localized over the whole sequence. Therefore, the three-dimensional structures of other mammalian ribonucleotide reductase R2 proteins are expected to be very similar to that of the mouse enzyme. In mouse R2 a narrow hydrophobic channel leads to the proposed binding site for molecular oxygen near to the iron-radical site in the interior of the protein. In E. coli R2 this channel is blocked by the phenyl ring of a tyrosine residue, which in mouse R2 is a serine. These structural variations may explain the observed differences in sensitivity to radical scavengers. The structure determination is based on diffraction data from crystals grown at pH 4.7. Unexpectedly, the protein is not iron-free, but contains one iron ion bound at one of the dinuclear iron sites. This ferric ion is bound with partial occupancy and is coordinated by three glutamic acids (one bidentate) and one histidine in a bipyramidal coordination that has a free apical coordination position. Soaking of crystals in a solution of ferrous salt at pH 4.7 increased the occupancy on the already occupied site, but without any detectable binding at the second site.

Structural basis for AMPA receptor activation and ligand selectivity: crystal structures of five agonist complexes with the GluR2 ligand-binding core.

Glutamate is the principal excitatory neurotransmitter within the mammalian CNS, playing an important role in many different functions in the brain such as learning and memory. In this study, a combination of molecular biology, X-ray structure determinations, as well as electrophysiology and binding experiments, has been used to increase our knowledge concerning the ionotropic glutamate receptor GluR2 at the molecular level. Five high-resolution X-ray structures of the ligand-binding domain of GluR2 (S1S2J) complexed with the three agonists (S)-2-amino-3-[3-hydroxy-5-(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl]propionic acid (2-Me-Tet-AMPA), (S)-2-amino-3-(3-carboxy-5-methylisoxazol-4-yl)propionic acid (ACPA), and (S)-2-amino-3-(4-bromo-3-hydroxy-isoxazol-5-yl)propionic acid (Br-HIBO), as well as of a mutant thereof (S1S2J-Y702F) in complex with ACPA and Br-HIBO, have been determined. The structures reveal that AMPA agonists with an isoxazole moiety adopt different binding modes in the receptor, dependent on the substituents of the isoxazole. Br-HIBO displays selectivity among different AMPA receptor subunits, and the design and structure determination of the S1S2J-Y702F mutant in complex with Br-HIBO and ACPA have allowed us to explain the molecular mechanism behind this selectivity and to identify key residues for ligand recognition. The agonists induce the same degree of domain closure as AMPA, except for Br-HIBO, which shows a slightly lower degree of domain closure. An excellent correlation between domain closure and efficacy has been obtained from electrophysiology experiments undertaken on non-desensitising GluR2i(Q)-L483Y receptors expressed in oocytes, providing strong evidence that receptor activation occurs as a result of domain closure. The structural results, combined with the functional studies on the full-length receptor, form a powerful platform for the design of new selective agonists.

Structure and function of the N-linked glycans of HBP/CAP37/azurocidin: crystal structure determination and biological characterization of nonglycosylated HBP.

The three N-glycosylation sites of human heparin binding protein (HBP) have been mutated to produce a nonglycosylated HBP (ng-HBP) mutant. ng-HBP has been crystallized and tested for biological activity. Complete X-ray data have been collected to 2.1 A resolution, and the structure has been fully refined to an R-factor of 18.4% (R(free) 27.7%). The ng-HBP structure reveals that neither the secondary nor tertiary structure have changed due to the removal of the glycosylation, as compared to the previously determined glycosylated HBP structure. Although the primary events in N-linked glycosylation occurs concomitant with polypeptide synthesis and therefore possesses the ability to influence early events in protein folding, we see no evidence of glycosylation influencing the structure of the protein. The root-mean-square deviation between the superimposed structures was 0.24 A (on C alpha atoms), and only minor local structural differences are observed. Also, the overall stability of the protein seems to be unaffected by glycosylation, as judged by the B-factors derived from the two X-ray structures. The flexibility of a glycan site may be determined by the local polypeptide sequence and structure rather than the glycan itself. The biological in vitro activity assay data show that ng-HBP, contrary to glycosylated HBP, mediates only a very limited stimulation of the lipopolysaccharide induced cytokine release from human monocytes. In animal models of fecal peritonitis, glycosylated HBP treatment rescues mice from and an otherwise lethal injury. It appears that ng-HBP have significant effect on survival, and it can be concluded that ng-HBP can stimulate the host defence machinery albeit to a lesser extent than glycosylated HBP.

Characterization of the allosteric binding pocket of human liver fructose-1,6-bisphosphatase by protein crystallography and inhibitor activity studies.

The structures of three complexes of human fructose-1,6-bisphosphatase (FB) with the allosteric inhibitor AMP and two AMP analogues have been determined and all fully refined. The data used for structure determination were collected at cryogenic temperature (110 K), and with the use of synchrotron radiation. The structures reveal a common mode of binding for AMP and formycine monophosphate (FMP). 5-Amino-4-carboxamido-1 beta-D-5-phosphate-ribofuranosyl-1H-imidazole (AICAR-P) shows an unexpected mode of binding to FB, different from that of the other two ligands. The imidazole ring of AICAR-P is rotated 180 degrees compared to the AMP and FMP bases. This rotation results in a slightly different hydrogen bonding pattern and minor changes in the water structure in the binding pocket. Common features of binding are seen for the ribose and phosphate moieties of all three compounds. Although binding in a different mode, AICAR-P is still capable of making all the important interactions with the residues building the allosteric binding pocket. The IC50 values of AMP, FMP, and AICAR-P were determined to be 1.7, 1.4, and 20.9 microM, respectively. Thus, the approximately 10 times lower potency of AICAR-P is difficult to explain solely from the variations observed in the binding pocket. Only one water molecule in the allosteric binding pocket was found to be conserved in all four subunits in all three structures. This water molecule coordinates to a phosphate oxygen atom and the N7 atom of the AMP molecule, and to similarly situated atoms in the FMP and AICAR-P complexes. This implies an important role of the conserved water molecule in binding of the ligand.

Crystallization and crystallographic investigations of the small subunit of mouse ribonucleotide reductase.

The R2 protein component of mouse ribonucleotide reductase has been obtained from overproducing Escherichia coli bacteria. It has been crystallized using NaCl as precipitant. The crystals are orthorhombic, space group C222(1), with cell dimensions a = 76.9 A, b = 108.9 A, c = 92.7 A and diffract to at least 2.5 A. The asymmetric unit of the crystals contains one monomer. Rotation and translation function searches using a model based on the weakly homologous E. coli R2 gave one significant peak. Rotation about a crystallographic 2-fold axis parallel to the a-axis produces an R2 dimer with dimer interactions very similar to those found for E. coli R2.

Crystal structure of tetranectin, a trimeric plasminogen-binding protein with an alpha-helical coiled coil.

Tetranectin is a plasminogen kringle 4-binding protein. The crystal structure has been determined at 2.8 A resolution using molecular replacement. Human tetranectin is a homotrimer forming a triple alpha-helical coiled coil. Each monomer consists of a carbohydrate recognition domain (CRD) connected to a long alpha-helix. Tetranectin has been classified in a distinct group of the C-type lectin superfamily but has structural similarity to the proteins in the group of collectins. Tetranectin has three intramolecular disulfide bridges. Two of these are conserved in the C-type lectin superfamily, whereas the third is present only in long-form CRDs. Tetranectin represents the first structure of a long-form CRD with intact calcium-binding sites. In tetranectin, the third disulfide bridge tethers the CRD to the long helix in the coiled coil. The trimerization of tetranectin as well as the fixation of the CRDs relative to the helices in the coiled coil indicate a demand for high specificity in the recognition and binding of ligands.

Estimated intake of benzoic and sorbic acids in Denmark.

The monitoring of food additives and recent dietary surveys carried out in Denmark have earlier been used to estimate the intake of sweeteners and nitrite in relation to acceptable daily intakes. The ubiquitous use of the preservatives benzoic and sorbic acids raises the question of the magnitude of the intake of these preservatives in relation to acceptable daily intakes. This area is explored in this paper. The content of benzoic and sorbic acids in all food groups, where they are allowed, was monitored in Denmark 17 times between 2001 and 2006 with a total of 1526 samples. Transgressions of maximum limits, illegal use or declaration faults were found in about 3% of samples. From repeated investigations on fat-based foods (salads and dressings), marmalade and stewed fruit, it is concluded that the amounts used in industry have been relatively stable throughout the whole period, although limited data for marmalade show some variation. Most foods in the categories soft drinks, dressings, fat-based salads, pickled herrings, and marmalade contain benzoic and sorbic acid, and sliced bread also contains in some cases sorbic acid. The median daily intake and intake distribution of benzoic and sorbic acids were calculated with data from the Danish National Survey of Dietary Habits and Physical Activity (age from 4 to 75 years) conducted in 2000-2004 with 5785 participants. The median intakes of both benzoic acid and sorbic acid are well below the acceptable daily intakes of 0-5 and 0-25 mg kg(-1) body weight (bw) day(-1) for benzoic and sorbic acid, respectively. However, the 90th percentile based on the average of the samples with a content of benzoic acid is higher than the acceptable daily intake for both men and women, with the highest value of 16 mg kg(-1) bw day(-1) for both boys and girls in the 4-6-year-old age group. Based on the average of all samples, the 95th percentile is over the acceptable daily intake for men up to 34 years and for women up to 24 years, and the 90th percentile for men up to 18 years and for women up to 10 years. Soft drinks, salads and dressings are the main contributors to benzoic acid intake. The sorbic acid intake based on the average of all samples is well below the acceptable daily intake. However, for the intake based on the average of samples with content, the 95th percentile exceeds the acceptable daily intake. This is caused by the dominating contribution to the intake of sorbic acid from sliced bread, but since only seven out of 42 samples have added sorbic acid, the calculation based on the average of samples with content will exaggerate the intake. With a built-in safety factor of 100 in the acceptable daily intakes and judging from the literature, the high intakes of benzoic acid should not cause any concern for ill-effects. However, there must be a reason to reconsider the maximum limits especially for benzoic acid in soft drinks, dressings and salads and for sorbic acid in sliced bread.

Community-acquired adenovirus pneumonia in a patient with chronic lymphatic leukaemia.

Described here is a severe case of community-acquired adenovirus pneumonia that occurred in a previously healthy 54-year-old male who was later determined to have stage A chronic lymphatic leukemia. The clinical presentation was consistent with that of atypical pneumonia. Testing with PCR revealed adenovirus in a bronchoalveolar lavage sample, while all other tests to determine a bacterial or virological etiology were negative. Further examination of the patient revealed the previously undiagnosed chronic lymphatic leukemia. Following treatment with human immunoglobulin and oxygen therapy with continuous positive airway pressure support the patient recovered from the pneumonia completely.

Caracemide, a site-specific irreversible inhibitor of protein R1 of Escherichia coli ribonucleotide reductase.

The anticancer drug caracemide, N-acetyl-N,O- di(methylcarbamoyl)hydroxylamine, and one of its degradation products, N-acetyl-O-methylcarbamoyl-hydroxylamine, were found to inhibit the enzyme ribonucleotide reductase of Escherichia coli by specific interaction with its larger component protein R1. No effect on the smaller protein R2 was observed. The effect of the degradation product was about 30 times lower than that of caracemide itself. The caracemide inactivation of R1 is irreversible, with an apparent second-order rate constant of 150 M-1 s-1. The R1R2 holoenzyme was approximately 30 times more sensitive to caracemide inactivation than the isolated R1 protein. The ribonucleotide reductase substrates were potent competitors of the caracemide inhibition, with a Kdiss for GDP binding to R1 of 80 microM. The reducing agent dithiothreitol was also found to be a potent competitor of caracemide inactivation. These results indicate that caracemide inactivates R1 by covalent modification at the substrate-binding site. By analogy with the known interaction between caracemide and acetylcholinesterase or choline acetyltransferase, we propose that the modification of R1 occurs at an activated cysteine or serine residue in the active site of the enzyme.

Atomic resolution structure of human HBP/CAP37/azurocidin.

Crystals of human heparin binding protein (HBP) diffract to 1.1 A when flash-frozen at 120 K. The atomic resolution structure has been refined anisotropically using SHELXL96. The final model of HBP consists of 221 amino-acid residues of 225 possible, three glycosylation units, one chloride ion, 15 precipitant ethanol molecules and 323 water molecules. The structure is refined to a final crystallographic R factor of 15.9% and Rfree(5%) of 18.9% using all data. A putative protein kinase C activation site has been identified, involving residues 113-120. The structure is compared to the previously determined 2.3 A resolution structure of HBP.

Expression, crystallization and preliminary X-ray analysis of the two amino-terminal Ig domains of the neural cell adhesion molecule (NCAM).

The two amino-terminal Ig domains of the rat neural cell adhesion molecule, NCAM, have been expressed in the yeast strain Pichia pastoris. The double domain consisting of 191 amino acids was overexpressed, purified and crystallized. The crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 47.1, b = 122.5, c = 72.9 A and beta = 98.3 degrees. Assuming there are four double domains per asymmetric unit, V(m) is estimated to be 2.41 A(3) Da(-1) and the solvent content to be 42.3%. A native data set has been collected from a single flash-frozen crystal to 1.85 A resolution.

Use of a disposable sheath system for flexible sigmoidoscopy in decentralized colorectal cancer screening.

BACKGROUND AND STUDY AIMS: To prevent transmission of infectious agents and to reduce instrument reprocessing time, the use of disposable sheath systems instead of conventionally reprocessed endoscopes has been promoted for flexible sigmoidoscopy. This trial primarily investigated the feasibility of a disposable sheath system for flexible sigmoidoscopy in decentralized colorectal cancer screening. PATIENTS AND METHODS: In an ongoing colorectal cancer screening trial, 226 consecutive participants were randomly allocated to have their flexible sigmoidoscopy performed with either a fiberoptic sigmoidoscope covered with a disposable sheath ("EndoSheath group") or a conventional video colonoscope ("standard colonoscope group"). All examinations were performed at a temporary screening center. The patients' experience was documented using a questionnaire. The feasibility of running temporary screening units was evaluated. RESULTS: Examinations beyond the 60-cm level were excluded. Thus, 113 patients (examined with the disposable instrument) and 87 (standard instrument) were eligible for analysis. When the sheathed system was used, all the devices needed could be satisfactorily transported. A screening center could be set up within a few hours. No differences were observed in patient discomfort. Fewer patients with polyps were observed in the EndoSheath group (48 [42%]), compared with 55 (63%) in the standard colonoscope group; P = 0.005). No significant differences were observed for polyps larger than 5 mm (14 [12%] in the EndoSheath group, 13 [15%] in the standard colonoscope group; P = 0.6). CONCLUSIONS: Using the disposable system, decentralized colorectal cancer screening was easily established. However, fewer polyps were found, possibly due to the fiberoptic nature of the instrument. Sheathed video instruments are desirable and may increase the diagnostic yield.

Human plasminogen binding protein tetranectin: crystallization and preliminary X-ray analysis of the C-type lectin CRD and the full-length protein.

The recombinant human plasminogen binding protein tetranectin (TN) and the C-type lectin CRD of this protein (TN3) have been crystallized. TN3 crystallizes in the tetragonal space group P4(2)2(1)2 with cell dimensions a = b = 64.0, c = 75.7 A and with one molecule per asymmetric unit. The crystals diffract X-rays to at least 2.0 A resolution. A complete diffraction data set has been collected to 2.7 A resolution. The crystals of TN, obtained by the vapour-diffusion reverse salting-in method at 280 K, are rhombohedral, space group R3, with the hexagonal axes a = b = 89.1, c = 75.8 A, and diffract to at least 2.5 A. A full data set has been collected to 3.0 A. The asymmetric unit contains one monomer of TN. Molecular replacement solutions for TN3 and TN have been obtained using the structure of the C-type lectin CRD of rat mannose-binding protein as search model. The rhombohedral space group indicates that trimers of TN are formed in accordance with the observation of trimerization in solution.

Crystallization and molecular replacement solution of human heparin binding protein.

The highly glycosylated protein, human heparin binding protein, has been crystallized in the primitive orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 39.0, b = 66.2 and c = 101.4 A. Ethanol was used as precipitant and glycerol as additive. A full data set has been collected to 3.1 A and diffraction was observed to at least 2.3 A. A molecular replacement solution using human neutrophile elastase as a search model was obtained, showing one molecule per asymmetric unit. The crystal packing showed no bad contacts and the R factor was 44.8% after ten cycles of rigid-body refinement.

Structure of HBP, a multifunctional protein with a serine proteinase fold.

The structure of human heparin binding protein reveals that the serine proteinase fold has been used as a scaffold for a multifunctional protein with antibacterial activity, monocyte and t-cell activating properties and endotoxin and heparin binding capacity.

Structure of the C-type lectin carbohydrate recognition domain of human tetranectin.

Tetranectin (TN) is a C-type lectin involved in fibrinolysis, being the only endogenous ligand known to bind specifically to the kringle 4 domain of plasminogen. TN was originally isolated from plasma, but shows a wide tissue distribution. Furthermore, TN has been found in the extracellular matrix of certain human carcinomas, whereas none or little is present in the corresponding normal tissue. The crystal structure of full-length trimeric TN (2.8 A resolution) has recently been published [Nielsen et al. (1997). FEBS Lett. 412, 388-396]. The crystal structure of the carbohydrate recognition domain (CRD) of human TN (TN3) has been determined separately at 2.0 A resolution in order to obtain detailed information on the two calcium binding sites. This information is essential for the elucidation of the specificity of TN towards oligosaccharides. TN3 crystallizes as a dimer, whereas it appears as a monomer in solution. The overall fold of TN3 is similar to other known CRDs. Each monomer is built of two distinct regions, one region consisting of six beta-strands and two alpha-helices, and the other region is composed of four loops harboring two calcium ions. The calcium ion at site 1 forms an eightfold coordinated complex and has Asp116, Glu120, Gly147, Glu150, Asn151, and one water molecule as ligands. The calcium ion at site 2, which is believed to be involved in recognition and binding of oligosaccharides, is sevenfold coordinated with ligands Gln143, Asp145, Glu150, Asp165, and two water molecules. One sulfate ion has been located at the surface of TN3, forming contacts to Glu120, Lys148, Asn106 of a symmetry-related molecule, and to an ethanol molecule.

Crystallization and molecular-replacement solution of a truncated form of human recombinant tetranectin.

The two C-terminal domains, TN23 (residues 17-181), of human recombinant tetranectin, a plasminogen kringle 4 binding C-type lectin, have been crystallized in two different space groups. Using PEG 8000 as precipitant and at a pH of 8.5, crystals belonging to the monoclinic space group C2 are obtained, with unit-cell parameters a = 160.4, b = 44.7, c = 107.5 A, beta = 127.6 degrees. Using sodium formate as precipitant and at a pH of 5.0, TN23 crystallizes in a rhombohedral space group, with unit-cell parameters a = b = c = 107.4 A, alpha = beta = gamma = 78.3 degrees. A full data set to 4.5 A has been collected from the monoclinic crystals. Using the structure of full-length tetranectin, a molecular-replacement solution has been obtained. The crystal packing shows that TN23 crystallizes as a trimer, with one trimer in the asymmetric unit.