1Identification of genes differentially expressed in the embryonic pig cerebral cortex before and after appearance of gyration

Background

Mammalian evolution is characterized by a progressive expansion of the surface area of the cerebral cortex, an increase that is accompanied by gyration of the cortical surface. The mechanisms controlling this gyration process are not well characterized but mutational analyses indicate that genes involved in neuronal migration play an important function. Due to the lack of gyration of the rodent brain it is important to establish alternative models to examine brain development during the gyration process. The pig brain is gyrated and accordingly is a candidate alternative model.

Findings

In this study we have identified genes differentially expressed in the pig cerebral cortex before and after appearance of gyration. Pig cortical tissue from two time points in development representing a non-folded, lissencephalic, brain (embryonic day 60) and primary-folded, gyrencephalic, brain (embryonic day 80) were examined by whole genome expression microarray studies. 91 differentially expressed transcripts (fold change >3) were identified. 84 transcripts were annotated and encoding proteins involved in for example neuronal migration, calcium binding, and cytoskeletal structuring. Quantitative real-time PCR was used to confirm the regulation of a subset of the identified genes.

Conclusion

This study provides identification of genes which are differentially expressed in the pig cerebral cortex before and after appearance of brain gyration. The identified genes include novel candidate genes which could have functional importance for brain development.

The NIZP1 KRAB and C2HR domains cross-talk for transcriptional regulation

The NSD1 histone methyltransferase is involved in the outgrowth disorders Sotos and Weaver syndromes and childhood acute myeloid leukemia. NSD1 is a bona fida transcriptional co-repressor for Nizp1 which is a protein including SCAN, KRAB, C2HR and zinc-finger domains. In this study the Nizp1 KRAB-domain was identified to possess an intrinsic transcriptional activation capacity suppressed in cis by the presence of the C2HR domain. Oppositely, the KRAB-domain supported C2HR domain mediated transcriptional repression. The presence of the KRAB-domain resulted in increased NSD1 co-repressor association with the C2HR domain. This study shows a new function of the KRAB-domain, C2HR-domain, and the associated factors to confer Nizp1 mediated transcriptional regulation.

The GCKR rs780094 polymorphism is associated with elevated fasting serum triacylglycerol, reduced fasting and OGTT-related insulinaemia, and reduced risk of type 2 diabetes

AIMS/HYPOTHESIS

Recent genome-wide association studies have suggested that a polymorphism in GCKR, the gene encoding the glucokinase regulatory protein, is involved in triacylglycerol regulation. Our aim was to examine in large-scale studies the common GCKR rs780094 polymorphism in relation to metabolic traits (mainly fasting hypertriacylglycerolaemia) and traits related to pancreatic beta cell function.

METHODS

The polymorphism was genotyped in 16,853 Danes using Taqman allelic discrimination. Association was analysed in case-control studies and quantitative trait analyses. We also analysed the possible interactive effect between the GCK -30G>A polymorphism and the GCKR rs780094 variant on metabolic traits.

RESULTS

The minor GCKR A-allele of rs780094 is associated with an increased level of fasting serum triacylglycerol (p = 6 x 10(-14)), impaired fasting (p = 0.001) and OGTT-related insulin release (p = 3 x 10(-6)), reduced homeostasis model assessment of insulin resistance (p = 0.0004), WHO-defined dyslipidaemia (p = 6 x 10(-9)) and a modestly decreased risk of type 2 diabetes (p = 0.01). Significantly increased fasting serum insulin concentrations were demonstrated when analysing the GCK -30A and GCKR rs780094 G-alleles in an additive model.

CONCLUSIONS/INTERPRETATION

The GCKR rs780094 polymorphism, or another variant with which it is in tight linkage disequilibrium, is likely to increase glucokinase regulatory protein activity to induce improved glycaemic regulation at the expense of hypertriacylglycerolaemia as reflected in the present study of 16,853 Danes. We also suggest an additive effect of GCK and GCKR risk alleles on [corrected] serum insulin release.

Expression Analysis of cPLA2 Alpha Interacting TIP60 in Diabetic KKAy and Non-Diabetic C57BL Wild-Type Mice: No Impact of Transient and Stable TIP60 Overexpression on Glucose-Stimulated Insulin Secretion in Pancreatic Beta-Cells

In the present study we investigate the expression levels of cytosolic phospholipase A2 alpha (cPLA2alpha) interacting histone acetyl transferase proteins TIP60alpha and TIP60beta in non-diabetic C57BL wild-type mice and obese type 2 diabetic KKAy model mice. The aim was to test our hypothesis that TIP60 plays a regulatory role in glucose-stimulated insulin secretion from pancreatic beta-cells.

MATERIAL AND METHODS

Ten obese diabetic KKAy mice and ten non-diabetic C57BL mice were fed a standard chow diet. After nine weeks, islet RNA was purified and used to measure TIP60 expression. We investigated the effect of TIP60alpha and TIP60beta on glucose-stimulated insulin secretion by transient and stable overexpression in the pancreatic mouse beta-cell line MIN6 and the rat beta-cell line INS-1E.

RESULTS

We found that non-diabetic C57BL mice and diabetic KKAy mice have the same level of both the alpha and beta splice forms of TIP60. Furthermore, we demonstrated that transient and stable expression of TIP60 in INS-1E cells affects neither glucose-stimulated insulin secretion, insulin output nor cell insulin content. Also susceptibility to developing gluco-toxicity was unaffected.

CONCLUSION

TIP60 over-expression does not affect glucose stimulated insulin secretion, insulin content or abnormal beta-cell function during glucotoxicity.

Molecular characterization and temporal expression profiling of presenilins in the developing porcine brain

Background

The transmembrane presenilin (PSEN) proteins, PSEN1 and PSEN2, have been proposed to be the catalytic components of the γ-secretase protein complex, which is an intramembranous multimeric protease involved in development, cell regulatory processes, and neurodegeneration in Alzheimer's disease. Here we describe the sequencing, chromosomal mapping, and polymorphism analysis of PSEN1 and PSEN2 in the domestic pig (Sus scrofa domesticus).

Conclusion

The data provide evidence for structural and functional conservation of PSENs in mammalian lineages, and may suggest that the high sequence similarity and colocalization of PSEN1 and PSEN2 in brain tissue reflect a certain degree of functional redundancy. The data show that pigs may provide a new animal model for detailed analysis of the developmental functions of the PSENs.

Type III interferon (IFN) induces a type I IFN-like response in a restricted subset of cells through signaling pathways involving both the Jak-STAT pathway and the mitogen-activated protein kinases

Type III interferon (IFN) is a novel member of the interferon family. Type III IFN utilizes a receptor complex different from that of type I IFN, but both types of IFN induce STAT1, STAT2, and STAT3 activation. Here we describe a detailed comparison of signal transduction initiated by type I and type III IFN. Gene expression array analysis showed that IFN types I and III induced a similar subset of genes. In particular, no genes were induced uniquely by type III IFN. Next, we used chromatin immunoprecipitation (ChIP) analysis to investigate the promoter activation by types I and III IFN. The ChIP assays demonstrated that stimulation of cells with both type I and type III IFN resulted in the recruitment of ISGF3 transcription factor components to the promoter region of responsive genes and in an increase of polymerase II loading and histone acetylation. Whereas IFN type I signaling was observed for a broad spectrum of cell lines, type III IFN signaling was more restricted. The lack of IFN type III signaling was correlated with a low expression of the IL28Ra component of the IFN type III receptor, and IL28Ra overexpression was sufficient to restore IFN type III signaling. We also tested the activation of mitogen-activated protein (MAP) kinases by type III IFN and found that type III IFN relies strongly upon both p38 and JNK MAP kinases for gene induction.

Evidence implicating BRD1 with brain development and susceptibility to both schizophrenia and bipolar affective disorder

Linkage studies suggest that chromosome 22q12-13 may contain one or more shared susceptibility genes for schizophrenia (SZ) and bipolar affective disorder (BPD). In a Faeroese sample, we previously reported association between microsatellite markers located at 22q13.31-qtel and both disorders. The present study reports an association analysis across five genes (including 14 single nucleotide and two microsatellite polymorphisms) in this interval using a case-control sample of 162 BPD, 103 SZ patients and 200 controls. The bromodomain-containing 1 gene (BRD1), which encodes a putative regulator of transcription showed association with both disorders with minimal P-values of 0.0046 and 0.00001 for single marker and overall haplotype analysis, respectively. A specific BRD1 2-marker 'risk' haplotype showed a frequency of approximately 10% in the combined case group versus approximately 1% in controls (P-value 2.8 x 10(-7)). Expression analysis of BRD1 mRNA revealed widespread expression in mammalian brain tissue, which was substantiated by immunohistochemical detection of BRD1 protein in the nucleus, perikaryal cytosol and proximal dendrites of the neurons in the adult rat, rabbit and human CNS. Quantitative mRNA analysis in developing fetal pig brain revealed spatiotemporal differences with high expression at early embryonic stages, with intense nuclear and cytosolar immunohistochemical staining of the neuroepithelial layer and early neuroblasts, whilst more mature neurons at later embryonic stages had less nuclear staining. The results implicate BRD1 with SZ and BPD susceptibility and provide evidence that suggests a role for BRD1 in neurodevelopment.

Genetic polymorphism and sequence evolution of an alternatively spliced exon of the glial fibrillary acidic protein gene, GFAP

Isoform GFAPepsilon of the human cytoskeletal protein GFAP carries, as the result of alternative splicing of exon 7a of GFAP, a novel 42-amino-acid-long C-terminal region with binding capacity for the presenilin proteins. Here we show that exon 7a is present in a variety of mammals but absent from GFAP of chicken and fish. Comparison of the mouse and human GFAP exons showed an increased rate of nonsynonymous nucleotide substitutions in exon 7a compared to the other exons. This resulted in 10 nonconservative and 2 conservative amino acid substitutions and suggests that exon 7a has evolved under different functional constraints. Exons 7a of humans and higher primates are 100% identical apart from alanine codon 426, which is conserved in only 9% of the human alleles, while 21 and 70% of the alleles, respectively, have a valine or a threonine codon at that position. Threonine represents a potential phosphorylation site, and positive selection of that effect could explain the high allele frequency.

Mutations associated with a childhood leukodystrophy, Alexander disease, cause deficiency in dimerization of the cytoskeletal protein GFAP

Heterozygous, de novo mutations in the glial fibrillary acidic protein (GFAP) gene were recently found to be associated with Alexander disease. We examined the functional effect of such mutations, and observed a decrease in GFAP dimerization. This effect behaves in a dominant fashion and points towards a potential mechanism in pathogenesis.

Drinking in adulthood: similarities and differences in effects of adult roles for Hispanic ethnic groups and Anglos

OBJECTIVE

This study examines whether the adult social roles perspective. an approach that explains drinking behaviors for Anglos, similarly affects alcohol use by Cubans, Mexican Americans, Puerto Ricans and Other Hispanics (Central and South Americans).

METHOD

The 1993 National Household Survey on Drug Abuse, a national probability sample of the household population in the United States, is used. The sample utilized here (N= 13,822; 56.2% female) consisted of 9,388 Anglos, 611 Cubans, 2,459 Mexican Americans, 611 Puerto Ricans and 753 Central/South Americans age 18 and older. The outcome measures include past-year drinking, and for drinkers, heavy drinking and alcohol-related problems. Logistic regression analyses are conducted using Stata.

RESULTS

The results show that there are some ethnic differences in the effects of the adult social roles. Of particular importance is the finding that being married has anomalous effects for Cubans (heavy drinking), Mexican Americans (problems) and Other Hispanics (problems) compared with Anglos and the other Hispanic ethnic groups.

CONCLUSIONS

The adult social roles perspective has some utility for explaining Hispanic drinking patterns. Future research should consider not only traditional predictors of drinking but also such socio-cultural factors as acculturation and familism, to better understand adult alcohol use by members of Hispanic ethnic groups.

Drinking patterns among Hispanic adolescents: results from a national household survey

OBJECTIVE

This is one of the first studies to examine and compare alcohol use for adolescent Cubans, Mexican Americans, Puerto Ricans and other Hispanics.

METHOD

The data come from the 1993 National Household Survey on Drug Abuse (NHSDA), a national probability sample of the U.S. household population. The sample examined here (N = 1,865, 52% male) comprises 200 Cubans, 1,133 Mexican Americans, 255 Puerto Ricans and 277 Central/South Americans who were 12 to 17 years old. Drinking patterns are measured using a quantity-frequency index, and analyses are conducted using Stata.

RESULTS

In the cross-tabulations, no ethnic differences in drinking patterns are found for males or females, nor is there evidence of gender differences within ethnic groups, although there are some age differences in alcohol use. In the logistic regression analyses, two ethnic differences emerge, although the factors most consistently associated with drinking behaviors in these analyses are age, Spanish language use and urban residence. Additional analyses using the 1998 NHSDA suggest that ethnic differences in alcohol use may emerge in late adolescence/early adulthood.

CONCLUSIONS

Given the established findings of ethnic and gender differences in drinking among adult Hispanics, it is surprising that few differences are evidenced in adolescence. Future research should explore whether such differences emerge during the transition into adulthood and, if so, identify factors that produce them. In addition, to increase understanding of these ethnic groups' drinking patterns, future research should further investigate the factors associated with Hispanic adolescents' alcohol use, including both consideration of whether the predictors are the same across groups and of the role of sociocultural factors.

Heterochromatin formation in mammalian cells: interaction between histones and HP1 proteins

Members of the heterochromatin protein 1 (HP1) family are silencing nonhistone proteins. Here, we show that in P19 embryonal carcinoma (EC) nuclei, HP1 alpha, beta, and gamma form homo- and heteromers associated with nucleosomal core histones. In vitro, all three HP1s bind to tailed and tailless nucleosomes and specifically interact with the histone-fold of histone H3. Furthermore, HP1alpha interacts with the linker histone H1. HP1alpha binds to H3 and H1 through its chromodomain (CD) and hinge region, respectively. Interestingly, the Polycomb (Pc1/M33) CD also interacts with H3, and HP1alpha and Pc1/M33 binding to H3 is severely impaired by CD mutations known to abrogate HP1 and Polycomb silencing in Drosophila. These results define a novel function for the conserved CD and suggest that HP1 self-association and histone binding may play a crucial role in HP1-mediated heterochromatin assembly.

Creutzfeldt-Jakob disease segregating in a three generation Danish family

A three generation family is presented in which rapidly progressive, early-onset Creutzfeldt-Jakob disease without typical EEG changes segregates as an autosomal dominant disease. An aspartic acid to asparagine mutation at codon 178 of the prion gene, PRNP, co-segregates with the disease. As expected, the disease allele also carries the valine codon of the polymorphic valine/methionine codon 129 of the gene. In family members homozygous for this valine codon the disease was more rapidly progressive than in a heterozygous family member, who had a variant clinical phenotype. Definite neuropathological diagnosis required prion staining with specific antibodies.

Serum tetranectin and CA125 in endometrial adenocarcinoma

BACKGROUND

CA125 and tetranectin (TN) are prognostic markers in ovarian cancer. This study examines the values of these markers in endometrial cancer.

MATERIALS AND METHODS

TN and CA125 were determined preoperatively in 99 patients with primary endometrioid adenocarcinoma and evaluated in relation to tumor grade, stage and cancer survival.

RESULTS

The CA125 levels correlated significantly with tumor stage. Dichotomized according to a cut-off level of 35 U/ml, CA125 significantly correlated with cancer death. Multivariate regression analysis of cancer survival time showed that CA125 > 35 U/ml was not an independent factor when stage was introduced. TN levels were within the normal range in all patients and did not show any association with tumor grade, stage or survival.

CONCLUSIONS

The study confirmed the role of CA125 as a prognostic factor in endometrial cancer and may be of aid in pointing out patients at high risk, whereas tetranectin did not show any prognostic effect.

Examining drinking patterns and problems among hispanic groups: results from a national survey

OBJECTIVE

This study examines and compares the drinking patterns and problems of members of four Hispanic groups (Cubans, Mexican Americans, Puerto Ricans and other Hispanics) in the United States, with information presented by gender and age.

METHOD

The 1993 National Household Survey on Drug Abuse, a recent national probability sample of the household population aged 18 and over in the United States, is used. Data are obtained through in-person interviews. The sample includes 4,462 Hispanics of Cuban (n = 620), Mexican (n = 2,467), Puerto Rican (n = 619) and Central and South American (n = 756) origin. Analyses are conducted using SUDAAN.

RESULTS

There are significant differences across the Hispanic groups in their drinking patterns and problems. Among men, Mexican Americans report the most frequent and heavy drinking, and the greatest prevalence of drunkenness and alcohol-related problems. Cubans report the lowest percentages of such respondents, and Puerto Ricans and other Hispanics are in between the other two groups. For women, fewer ethnic differences are evidenced than for men. In general, Puerto Ricans and Mexican Americans drink more often and heavily and experience more problems than the other groups. Even after controlling for predictors of adult alcohol use, some ethnic differences in drinking persist.

CONCLUSIONS

The four Hispanic groups have different drinking patterns. More research is necessary to determine the factors associated with differences in drinking across Hispanic groups.

Interaction with members of the heterochromatin protein 1 (HP1) family and histone deacetylation are differentially involved in transcriptional silencing by members of the TIF1 family

Mammalian TIF1alpha and TIF1beta (KAP-1/KRIP-1) are related transcriptional intermediary factors that possess intrinsic silencing activity. TIF1alpha is believed to be a euchromatic target for liganded nuclear receptors, while TIF1beta may serve as a co-repressor for the large family of KRAB domain-containing zinc finger proteins. Here, we report an association of TIF1beta with both heterochromatin and euchromatin in interphase nuclei. Co-immunoprecipitation of nuclear extracts shows that endogenous TIF1beta, but not TIF1alpha, is associated with members of the heterochromatin protein 1 (HP1) family. However, in vitro, both TIF1alpha and TIF1beta interact with and phosphorylate the HP1 proteins. This interaction involves a conserved amino acid motif, which is critical for the silencing activity of TIF1beta but not TIF1alpha. We further show that trichostatin A, an inhibitor of histone deacetylases, can interfere with both TIF1 and HP1 silencing. The silencing activity of TIF1alpha appears to result chiefly from histone deacetylation, whereas that of TIF1beta may be mediated via both HP1 binding and histone deacetylation.

Assessment of pH and oxygen status during hemodialysis using the arterial blood line in patients with an arteriovenous fistula

BACKGROUND

In patients with arteriovenous fistulas, assessment of pH and oxygen status during hemodialysis (HD) using the extracorporeal dialysis arterial blood line is widely used both in daily routine and in most studies investigating hypoxia during HD. We designed this study to evaluate whether results of blood gas samples drawn from the extracorporeal arterial line were clinically acceptable in assessing oxygen status.

METHODS

We compared samples drawn from the extracorporeal arterial line with conventionally arterial punctures during 18 routine HD sessions. The samples were drawn simultaneously and analyzed immediately for blood gases, pH and hemoximetry values.

RESULTS

No significant difference was found between the values from the radial artery and the extracorporeal arterial blood line except for FMetHb.

CONCLUSION

Thus, obtaining samples from the extracorporeal dialysis arterial blood line to evaluate the parameters of the oxygen status (pH, pO(2), pCO(2), ctHb, sO(2), FCOHb and ctO(2)) during routine HD is a clinically convenient and accurate sampling approach.

Phase II study of gemcitabine and vindesine in patients with previously untreated non-resectable non-small-cell lung cancer

Because both vindesine and gemcitabine are active drugs in advanced non-small-cell lung cancer (NSCLC), with different modes of action and only partly overlapping toxicity, a phase II study was performed. Gemcitabine 1000 mg m(-2) was given on days 1, 8 and 15 every 4 weeks, while vindesine 3 mg m(-2) was administered weekly for 7 weeks, then every 2 weeks. A total of 42 patients with nonresectable NSCLC were included. The median age of patients was 56 years; 57% were men, 52% had adenocarcinoma, 31% squamous cell carcinoma and 17% had large-cell carcinoma. The performance status ranged from 0 to 2 with 83% in performance status 1. The majority (55%) had stage IV disease, while 40% had stage III B and 5% stage III A disease. WHO grade 3-4 leucopenia occurred in five patients (12%) and 9% had grade 4 neutropenia. Thrombocytopenia grade 3-4 was observed in six patients (15%). There were no septic death or bleeding episodes. One patient had a transient WHO grade 4 increase in bilirubin, and four patients had a decrease in glomerular filtration rate below the normal limit; one of these patients developed a non-reversible renal insufficiency. Ten patients (24%) complained of dyspnoea of uncertain mechanism, possibly involving bronchoconstriction. There were one complete and seven partial responses among 40 assessable patients (20%, 95% confidence limits 9-36%). Median response duration was 31 weeks (range 11-83 weeks) and median survival time 31 weeks (range 2-171 weeks). The current combination of gemcitabine and vindesine does not appear to be promising for further examination because of the toxicity and somewhat disappointing activity.

Oxygen and 2,3 biphosphoglycerate (2,3-BPG) during haemodialysis

Eleven patients with chronic renal failure who were being treated with haemodialysis three times a week were monitored for a total of 34 haemodialysis sessions. Erythrocyte 2,3-biphosphoglycerate (2,3-BPG) concentration was analysed immediately before initiation of bicarbonate haemodialysis and 1 h afterwards. The 2,3-BPG concentration was expressed relative to the haemoglobin tetramer (Hb4) concentration as the 2,3-BPG/Hb4 ratio and compared with blood gas analyses and biochemical variables important for characterizing uraemia. During the first hour of haemodialysis the 2,3-BPG/Hb4 ratio decreased (p < 0.002), but the magnitude of the decrease did not significantly correlate with the 2,3-BPG/Hb4 ratio measured before haemodialysis (p=0.104). The decrease is most likely to be caused by the haemodialysis procedure itself. Mechanical stress on the erythrocytes is believed to cause the 2,3-BPG to escape; it is then removed by haemodialysis. Physiologically, an increase in 2,3-BPG would be expected to counteract the hypoxia which is frequently observed during haemodialysis. However, the present results show the opposite, a decrease in 2,3-BPG. No significant correlation was shown between the haemoglobin concentration and the 2,3-BPG/Hb4 ratio before dialysis (p=0.414). The pH showed a significant positive correlation with the 2,3-BPG/Hb4 ratio before dialysis, whereas the arterial pO2 and the 2,3-BPG/Hb4 ratio before dialysis were insignificantly negatively correlated. The concentrations of calcium, phosphate, creatinine, urea and albumin did not correlate significantly with the change in 2,3-BPG/Hb4-ratio after 1 h. The 2,3-BPG/Hb4 ratio (p=0.03) sampled just before dialysis correlated significantly and positively with the total weekly dosage of erythropoietin given to the patients.

TIF1alpha: a possible link between KRAB zinc finger proteins and nuclear receptors

Ligand-induced gene activation by nuclear receptors (NRs) is thought to be mediated by transcriptional intermediary factors (TIFs), that interact with their ligand-dependent AF-2 activating domain. Included in the group of the putative AF-2 TIFs identified so far is TIF1alpha, a member of a new family of proteins which contains an N-terminal RBCC (RING finger-B boxes-coiled coil) motif and a C-terminal bromodomain preceded by a PHD finger. In addition to these conserved domains present in a number of transcriptional regulatory proteins, TIF1alpha was found to contain several protein-protein interaction sites. Of these, one specifically interacts with NRs bound to their agonistic ligand and not with NR mutants that are defective in the AF-2 activity. Immediately adjacent to this 'NR box', TIF1alpha contains an interaction site for members of the chromatin organization modifier (chromo) family, HP1alpha and MOD1, which both are heterochromatinic proteins. Finally, TIF1alpha also has a binding site for KRAB silencing domains of C2H2 zinc finger proteins. TIF1beta, another member of the TIF1 gene family, has some interacting partners in common with TIF1alpha. TIF1beta can interact with HP1alpha, MOD1 and KRAB domains, but apparently not with NRs. Both TIF1alpha and TIF1beta repress transcription when fused to a DNA binding domain in transiently transfected mammalian cells. A model discussing the potential function(s) of TIF1s in the control of transcription at the level of the chromatin template will be presented.

[The prognostic significance of progesterone receptor level in endometrial cancer]

Oestrogen receptor (ER) and progesterone receptor (PR) contents were determined by biochemical (dextran charcoal-coated (DCC) assay) and immunohistochemical (ICA) methods in biopsies from 145 primary endometrial adenocarcinomas. Correlations between receptor contents and cancer specific survival were examined in a multivariate analysis including histopathological characteristics. Median patient follow-up time was 67 months with 18 cancer deaths. "High" PR levels correlated significantly (p = 0.004) with survival, independently of stage risk group (stages Ia-Ib vs Ic-IV). Patient age and histological grade were prognostic factors in a univariate setting but these parameters were eliminated in the multivariate model. The association between PR contents and cancer survival suggests that determination of PR can be of importance in the evaluation of endometrial cancer.