Elevation of fatty acid desaturase 2 in esophageal adenocarcinoma increases polyunsaturated lipids and may exacerbate bile acid-induced DNA damage

Background

The risk of esophageal adenocarcinoma (EAC) is associated with gastro‐esophageal reflux disease (GERD) and obesity. Lipid metabolism‐targeted therapies decrease the risk of progressing from Barrett's esophagus (BE) to EAC, but the precise lipid metabolic changes and their roles in genotoxicity during EAC development are yet to be established.

Methods

Esophageal biopsies from the normal epithelium (NE), BE, and EAC, were analyzed using concurrent lipidomics and proteomics (n = 30) followed by orthogonal validation on independent samples using RNAseq transcriptomics (n = 22) and immunohistochemistry (IHC, n = 80). The EAC cell line FLO‐1 was treated with FADS2 selective inhibitor SC26196, and/or bile acid cocktail, followed by immunofluorescence staining for γH2AX.

Results

Metabolism‐focused Reactome analysis of the proteomics data revealed enrichment of fatty acid metabolism, ketone body metabolism, and biosynthesis of specialized pro‐resolving mediators in EAC pathogenesis. Lipidomics revealed progressive alterations (NE‐BE‐EAC) in glycerophospholipid synthesis with decreasing triglycerides and increasing phosphatidylcholine and phosphatidylethanolamine, and sphingolipid synthesis with decreasing dihydroceramide and increasing ceramides. Furthermore, a progressive increase in lipids with C20 fatty acids and polyunsaturated lipids with ≥4 double bonds were also observed. Integration with transcriptome data identified candidate enzymes for IHC validation: Δ4‐Desaturase, Sphingolipid 1 (DEGS1) which desaturates dihydroceramide to ceramide, and Δ5 and Δ6‐Desaturases (fatty acid desaturases, FADS1 and FADS2), responsible for polyunsaturation. All three enzymes showed significant increases from BE through dysplasia to EAC, but transcript levels of DEGS1 were decreased suggesting post‐translational regulation. Finally, the FADS2 selective inhibitor SC26196 significantly reduced polyunsaturated lipids with three and four double bonds and reduced bile acid‐induced DNA double‐strand breaks in FLO‐1 cells in vitro.

Conclusions

Integrated multiomics revealed sphingolipid and phospholipid metabolism rewiring during EAC development. FADS2 inhibition and reduction of the high polyunsaturated lipids effectively protected EAC cells from bile acid‐induced DNA damage in vitro, potentially through reduced lipid peroxidation.

Baseline neutrophil-lymphocyte ratio holds no prognostic value for esophageal and junctional adenocarcinoma in patients treated with neoadjuvant chemotherapy

BACKGROUND

Several studies have reported that neutrophil-lymphocyte ratio (NLR) can predict survival in esophageal and gastroesophageal junction adenocarcinoma, as it reflects systemic inflammation. Hence, we aimed to determine whether baseline NLR holds prognostic value for esophageal adenocarcinoma patients treated with neoadjuvant chemotherapy (nCT) followed by surgery.

METHODS

We studied the data of 139 patients that received nCT before undergoing esophagectomy with curative intent, all identified from a prospectively maintained database (1998-2016). Pretreatment hematology reports were used to calculate the baseline NLR. A receiver operating characteristic curve (ROC-curve) was plotted to determine an optimal cutoff value. NLR quartiles were used to display possible differences between groups in relation to overall survival (OS) and disease-free survival (DFS) using the method of Kaplan-Meier. Cox regression analysis was performed to assess the prognostic value of NLR.

RESULTS

The median OS and DFS times were 46 months (interquartile range [IQR]: 19-166) and 30 months (IQR: 13-166], respectively, for the entire cohort. The ROC-curve showed that NLR has no discriminating power for survival status (area under the curve = 0.462) and therefore no optimal cutoff value could be determined. There were no statistically significant differences in median OS times for NLR quartiles: 65 (Q1), 32 (Q2), 45 (Q3), and 46 months (Q4) (P = 0.926). Similarly, DFS showed no difference between quartile groups, with median survival times of 27 (Q1), 19 (Q2), 36 (Q3), and 20 months (Q4) (P = 0.973). Age, pN, pM, and resection margin were independent prognostic factors for both OS and DFS. On the contrary, NLR was not associated with OS or DFS in univariable and multivariable analyses.

CONCLUSION

Baseline NLR holds no prognostic value for esophageal and gastroesophageal junction adenocarcinoma patients treated with nCT in this study, in contrast to other recently published papers. This result questions the validity of NLR as a reliable prognostic indicator and its clinical usefulness in these patients.

The Impact of Signet Ring Cell Differentiation on Outcome in Patients with Esophageal and Gastroesophageal Junction Adenocarcinoma

Background

Little is known about the association between signet ring cell (SRC) differentiation and response to neoadjuvant chemotherapy (nCT) or neoadjuvant chemoradiotherapy (nCRT) in patients with esophageal and junctional adenocarcinoma (EAC). We aimed to assess if SRC differentiation is associated with survival and response to nCT or nCRT in patients with EAC.

Methods

Patients who underwent nCT and nCRT followed by surgery for EAC from 2000 until 2016 were identified from two institutional prospectively maintained databases. The pretreatment biopsy report or surgical resection specimen was used to differentiate patients into an SRC or non-SRC group.

Results

Overall, 129 (19%) of 689 patients included had SRCs (nCT: n = 64; nCRT: n = 65). The SRC group had a more advanced ypT stage (p = 0.003), a higher number of positive lymph nodes in the resection specimen {median (interquartile range [IQR]) 2 [0–5] vs. 1 [0–3]; p = 0.002} and a higher rate of R1/R2 resections (19.4% vs. 12%; p = 0.026). SRC differentiation was not an independent prognostic factor for overall survival (OS) or disease-free survival (DFS). Following nCT, the SRC group had significantly shorter DFS (median [IQR] 12 [5–50] vs. 23 [8–164]; p = 0.013), but not OS, compared with the non-SRC group. In contrast, no differences according to SRC status for OS or DFS were found in patients who underwent nCRT.

Conclusions

SRC differentiation was not independently associated with worse OS in patients with EAC who underwent neoadjuvant therapy and surgery. However, nCRT was associated with greater tumor downstaging and better DFS.

Electronic supplementary material

The online version of this article (10.1245/s10434-019-07322-x) contains supplementary material, which is available to authorized users.

A common intronic variant of PARP1 confers melanoma risk and mediates melanocyte growth via regulation of MITF

Previous genome-wide association studies have identified a melanoma-associated locus at 1q42.1 that encompasses a ∼100-kb region spanning the PARP1 gene. Expression quantitative trait locus (eQTL) analysis in multiple cell types of the melanocytic lineage consistently demonstrated that the 1q42.1 melanoma risk allele (rs3219090[G]) is correlated with higher PARP1 levels. In silico fine-mapping and functional validation identified a common intronic indel, rs144361550 (-/GGGCCC; r2 = 0.947 with rs3219090), as displaying allele-specific transcriptional activity. A proteomic screen identified RECQL as binding to rs144361550 in an allele-preferential manner. In human primary melanocytes, PARP1 promoted cell proliferation and rescued BRAFV600E-induced senescence phenotypes in a PARylation-independent manner. PARP1 also transformed TERT-immortalized melanocytes expressing BRAFV600E. PARP1-mediated senescence rescue was accompanied by transcriptional activation of the melanocyte-lineage survival oncogene MITF, highlighting a new role for PARP1 in melanomagenesis.

Abstract 4487: An INDEL variant confers melanoma risk through PARP1 expression regulation

Recent genome wide association studies identified several new loci for melanoma susceptibility including chr1q42.1 locus encompassing Poly [ADP-ribose] polymerase 1 (PARP1). As an effort to identify effecter genes and functional risk variants from this locus we performed expression quantitative trait loci (eQTL) analysis in 62 melanoma cell lines. Among the genes in 1Mb area eQTL was identified for PARP1 and subsequently validated by qPCR, where increased PARP1 levels are significantly correlated with the risk allele (p = 0.03, copy number adjusted). Further allele discrimination qPCR of PARP1 transcripts in 14 melanoma cell lines heterozygous and of neutral copy for the lead SNP indicated significantly higher proportion for the risk allele (p = .0001). Same allelic imbalance was also observed in 51 heterozygous melanomas with neutral copy numbers from The Cancer Genome Atlas (p = .028). To identify functional risk variants mediating these effects we annotated this locus using six melanoma relevant cell types available from ENCODE and Roadmap database. Based on recent fine mapping data suggesting single-SNP model for this locus we prioritized high LD variants for nomination. Among 65 SNPs of high LD with the lead SNP or imputed best SNP (r2>0.6 using 1000 Genomes phase3), four exhibited strong evidence as potential transcriptional enhancers. Electro Mobility Shift Assays and luciferase assays on these four variants demonstrated that one of them, a six-base pair INDEL (-/GGGCCC) in the first intron, displayed strong allelic functionality. Consistent with the expression data melanoma-associated deletion allele results in higher luciferase activity while protective insertion allele binds a group of proteins with higher affinity. Subsequent comparative mass-spectrometry for these insertion-binding proteins identified a striking collection of Guanine-quadruplex binding proteins including RECQ1 as potential inhibitors of PARP1 expression. Consistent with this hypothesis over-expression of RECQL results in more pronounced allelic difference in luciferase activities indicating that RECQ1 contributes to allelic PARP1 expression. Further interrogation of RECQ1 and PARP1 expression correlation analysis suggested that RECQ1 levels are inversely correlated with PARP1 in melanomas carrying insertion alleles. These data demonstrate that increased PARP1 expression is correlated with melanoma risk and an INDEL variant mediates differential PARP1 expression possibly through secondary DNA structure binding proteins including RECQ1.

Citation Format: Jiyeon Choi, Matthew Makowski, Tongwu Zhang, Matthew Law, Wendy Kim, Michael Kovacs, Hemang Parikh, Lauren Aoude, Michael Gartside, Jeffrey Trent, Michiel Vermeulen, Stuart Macgregor, Nicholas Hayward, Mai Xu, Kevin Brown. An INDEL variant confers melanoma risk through PARP1 expression regulation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4487.

POLE mutations in families predisposed to cutaneous melanoma

Germline mutations in the exonuclease domain of POLE have been shown to predispose to colorectal cancers and adenomas. POLE is an enzyme involved in DNA repair and chromosomal DNA replication. In order to assess whether such mutations might also predispose to cutaneous melanoma, we interrogated whole-genome and exome data from probands of 34 melanoma families lacking pathogenic mutations in known high penetrance melanoma susceptibility genes: CDKN2A, CDK4, BAP1, TERT, POT1, ACD and TERF2IP. We found a novel germline mutation, POLE p.(Trp347Cys), in a 7-case cutaneous melanoma family. Functional assays in S. pombe showed that this mutation led to an increased DNA mutation rate comparable to that seen with a Pol ε mutant with no exonuclease activity. We then performed targeted sequencing of POLE in 1243 cutaneous melanoma cases and found that a further ten probands had novel or rare variants in the exonuclease domain of POLE. Although this frequency is not significantly higher than that in unselected Caucasian controls, we observed multiple cancer types in the melanoma families, suggesting that some germline POLE mutations may predispose to a broad spectrum of cancers, including melanoma. In addition, we found the first mutation outside the exonuclease domain, p.(Gln520Arg), in a family with an extensive history of colorectal cancer.

Nonsense mutations in the shelterin complex genes ACD and TERF2IP in familial melanoma

BACKGROUND

The shelterin complex protects chromosomal ends by regulating how the telomerase complex interacts with telomeres. Following the recent finding in familial melanoma of inactivating germline mutations in POT1, encoding a member of the shelterin complex, we searched for mutations in the other five components of the shelterin complex in melanoma families.

METHODS

Next-generation sequencing techniques were used to screen 510 melanoma families (with unknown genetic etiology) and control cohorts for mutations in shelterin complex encoding genes: ACD, TERF2IP, TERF1, TERF2, and TINF 2. Maximum likelihood and LOD [logarithm (base 10) of odds] analyses were used. Mutation clustering was assessed with χ(2) and Fisher's exact tests. P values under .05 were considered statistically significant (one-tailed with Yates' correction).

RESULTS

Six families had mutations in ACD and four families carried TERF2IP variants, which included nonsense mutations in both genes (p.Q320X and p.R364X, respectively) and point mutations that cosegregated with melanoma. Of five distinct mutations in ACD, four clustered in the POT1 binding domain, including p.Q320X. This clustering of novel mutations in the POT1 binding domain of ACD was statistically higher (P = .005) in melanoma probands compared with population control individuals (n = 6785), as were all novel and rare variants in both ACD (P = .040) and TERF2IP (P = .022). Families carrying ACD and TERF2IP mutations were also enriched with other cancer types, suggesting that these variants also predispose to a broader spectrum of cancers than just melanoma. Novel mutations were also observed in TERF1, TERF2, and TINF2, but these were not convincingly associated with melanoma.

CONCLUSIONS

Our findings add to the growing support for telomere dysregulation as a key process associated with melanoma susceptibility.

FGFR2 point mutations in 466 endometrioid endometrial tumors: relationship with MSI, KRAS, PIK3CA, CTNNB1 mutations and clinicopathological features

Mutations in multiple oncogenes including KRAS, CTNNB1, PIK3CA and FGFR2 have been identified in endometrial cancer. The aim of this study was to provide insight into the clinicopathological features associated with patterns of mutation in these genes, a necessary step in planning targeted therapies for endometrial cancer. 466 endometrioid endometrial tumors were tested for mutations in FGFR2, KRAS, CTNNB1, and PIK3CA. The relationships between mutation status, tumor microsatellite instability (MSI) and clinicopathological features including overall survival (OS) and disease-free survival (DFS) were evaluated using Kaplan-Meier survival analysis and Cox proportional hazard models. Mutations were identified in FGFR2 (48/466); KRAS (87/464); CTNNB1 (88/454) and PIK3CA (104/464). KRAS and FGFR2 mutations were significantly more common, and CTNNB1 mutations less common, in MSI positive tumors. KRAS and FGFR2 occurred in a near mutually exclusive pattern (p = 0.05) and, surprisingly, mutations in KRAS and CTNNB1 also occurred in a near mutually exclusive pattern (p = 0.0002). Multivariate analysis revealed that mutation in KRAS and FGFR2 showed a trend (p = 0.06) towards longer and shorter DFS, respectively. In the 386 patients with early stage disease (stage I and II), FGFR2 mutation was significantly associated with shorter DFS (HR = 3.24; 95% confidence interval, CI, 1.35-7.77; p = 0.008) and OS (HR = 2.00; 95% CI 1.09-3.65; p = 0.025) and KRAS was associated with longer DFS (HR = 0.23; 95% CI 0.05-0.97; p = 0.045). In conclusion, although KRAS and FGFR2 mutations share similar activation of the MAPK pathway, our data suggest very different roles in tumor biology. This has implications for the implementation of anti-FGFR or anti-MEK biologic therapies.

Global expression profiling of murine MEN1-associated tumors reveals a regulatory role for menin in transcription, cell cycle and chromatin remodelling

Although the identification of menin-interacting partners and other evidence support a role for menin, the multiple endocrine neoplasia type 1 gene (MEN1) product, in regulating gene expression, little is known about the cellular pathways dysregulated by menin loss during tumorigenesis. The mouse models of MEN1 accurately mimic the human syndrome and provide an opportunity to assess the transcriptional effects of Men1 deletion in different endocrine tumor types to identify common pathway aberrations underlying tumorigenesis in MEN1-affected tissues. We compared the global gene expression profiles of pituitary adenomas and pancreatic islet tumors with control tissues from wild-type littermates. Amongst the 551 differentially expressed genes was significant over-representation of genes associated with chromatin remodelling, transcription and cell cycling, including some genes known to encode menin-binding partners, e.g., Rhox5 and Mll1. Consistent with increased cell-cycle transition from G1 to S phase was an elevation of Cdc7 expression in the tumors, which was confirmed by qRT-PCR using independent samples. In support of previous findings in islet tumors, we found down-regulation of the cell-cycle regulator, p18, in both the pancreatic islet and pituitary adenomas, suggesting that reduced p18 levels may be important for Men1-related tumorigenesis in multiple tissues. Surprisingly, we identified increased p16 transcript in pancreatic islet and pituitary tumors. This was accompanied by increased cytoplasmic localization p16 protein in tumor cells. The specific genes and general pathways we have found to be commonly dysregulated in MEN1 tumors, provide a platform for determining their roles in endocrine tumorigenesis.

Broad tumor spectrum in a mouse model of multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is an inherited cancer predisposition syndrome typified by development of tumors in parathyroid, pituitary and endocrine pancreas, as well as less common sites including both endocrine and nonendocrine organs. Deletion or mutation of the tumor suppressor gene MEN1 on chromosome 11 has been identified in many cases of MEN1 as well as in sporadic tumors. The molecular biology of menin, the protein encoded by MEN1, remains poorly understood. Here we describe a mouse model of MEN1 in which tumors were seen in pancreatic islets, pituitary, thyroid and parathyroid, adrenal glands, testes and ovaries. The observed tumor spectrum therefore includes types commonly seen in MEN1 patients and additional types. Pancreatic pathology was most common, evident in over 80% of animals, while other tumor types developed with lower frequency and generally later onset. Tumors of multiple endocrine organs were observed frequently, but progression to carcinoma and metastasis were not evident. Tumors in all sites showed loss of heterozygosity at the Men1 locus, though the frequency in testicular tumors was only 36%, indicating that a different molecular mechanism of tumorigenesis occurs in those Leydig tumors that do not show loss of the normal Men1 allele. Menin expression was below the level of detection in ovary, thyroid and testis, but loss of nuclear menin immunoreactivity was observed uniformly in all pancreatic islet adenomas and in some hyperplastic islet cells, suggesting that complete loss of Men1 is a critical point in islet tumor progression in this model.

Association between chronic fatigue syndrome and the corticosteroid-binding globulin gene ALA SER224 polymorphism

Chronic fatigue syndrome (CFS) is characterized by idiopathic fatigue of greater than 6 months' duration with postexertional exacerbation and many other symptoms. A trend toward relative hypocortisolism is described in CFS. Twin and family studies indicate a substantial genetic etiologic component to CFS. Recently, severe corticosteroid-binding globulin (CBG) gene mutations have been associated with CFS in isolated kindreds. Human leukocyte elastase, an enzyme important in CBG catabolism at inflammatory sites, is reported to be elevated in CFS. We hypothesized that CBG gene polymorphisms may act as a genetic risk factor for CFS. A total of 248 patients with CFS defined by Centers for Disease Control criteria, and 248 controls were recruited. Sequencing and restriction enzyme testing of the CBG gene coding region allowed detection of severe CBG gene mutations and a common exon 3 polymorphism (c.825G-->T, Ala-Ser224). Plasma CBG levels were measured in 125 CFS patients and 198 controls by radioimmunoassay. Total and free (calculated and measured) cortisol levels were ascertained in single samples between 8-10 a.m. The age of onset (mid 30s) and gender ratio (2.2:1, female:male) of the patients were similar to those reported in U.S. epidemiologic studies. A trend toward a preponderance of serine224 homozygosity among the CFS patients was noted, compared with controls (chi2 = 5.31, P = 0.07). Immunoreactive-CBG (IR-CBG) levels were higher in Serine/Alanine (Ser/Ala) than Ala/Ala subjects and higher again in Ser/Ser subjects, this effect was strongest in controls; Ser/Ser: 46.1+/-1.8 (n = 31, P = 0.03) vs. Ser/Ala: 42.4+/-1.0 (n = 56, P = 0.05) vs. Ala/Ala: 40.8+/-1.7 microg/mL (n = 21). Despite higher CBG levels, there was a nonsignificant trend toward lower total and free plasma cortisol in serine allele positive patients, total cortisol: Ser/Ser: 13.3+/-1.4 (n = 34) vs. Ser/Ala: 14.0+/-0.7 (n = 66) vs. Ala/Ala: 15.4+/-1.0 (n = 23). Homozygosity for the serine allele of the CBG gene may predispose to CFS, perhaps due to an effect on hypothalamic-pituitary-adrenal axis function related to altered CBG-cortisol transport function or immune-cortisol interactions.

Characterization of RasGRP2, a plasma membrane-targeted, dual specificity Ras/Rap exchange factor

Ras proteins operate as molecular switches in signal transduction pathways downstream of tyrosine kinases and G-protein-coupled receptors. Ras is switched from the inactive GDP-bound state to the active GTP-bound state by guanine nucleotide exchange factors (GEFs). We report here the cloning and characterization of RasGRP2, a longer alternatively spliced form of the recently cloned RapGEF, CalDAG-GEFI. A unique feature of RasGRP2 is that it is targeted to the plasma membrane by a combination of N-terminal myristoylation and palmitoylation. In vivo, RasGRP2 selectively catalyzes nucleotide exchange on N- and Ki-Ras, but not Ha-Ras. RasGRP2 also catalyzes nucleotide exchange on Rap1, but this RapGEF activity is less potent than that associated with CalDAG-GEFI. The nucleotide exchange activity of RasGRP2 toward N-Ras is stimulated by diacylglycerol and inhibited by calcium. The effects of diacylglycerol and calcium are additive but are not accompanied by any detectable change in the subcellular localization of RasGRP2. In contrast, CalDAG-GEFI is localized predominantly to the cytosol and lacks Ras exchange activity in vivo. However, prolonged exposure to phorbol esters, or growth in serum, results in localization of CalDAG-GEFI to the cell membrane and restoration of Ras exchange activity. Expression of RasGRP2 or CalDAG-GEFI in NIH3T3 cells transfected with wild type N-Ras results in an accelerated growth rate but not morphologic transformation. Thus, under appropriate growth conditions, CalDAG-GEFI and RasGRP2 are dual specificity Ras and Rap exchange factors.

Mice lacking the vascular endothelial growth factor-B gene (Vegfb) have smaller hearts, dysfunctional coronary vasculature, and impaired recovery from cardiac ischemia

Vascular endothelial growth factor-B (VEGF-B) is closely related to VEGF-A, an effector of blood vessel growth during development and disease and a strong candidate for angiogenic therapies. To further study the in vivo function of VEGF-B, we have generated Vegfb knockout mice (Vegfb(-/-)). Unlike Vegfa knockout mice, which die during embryogenesis, Vegfb(-/-) mice are healthy and fertile. Despite appearing overtly normal, Vegfb(-/-) hearts are reduced in size and display vascular dysfunction after coronary occlusion and impaired recovery from experimentally induced myocardial ischemia. These findings reveal a role for VEGF-B in the development or function of coronary vasculature and suggest potential clinical use in therapeutic angiogenesis.

Insertion/deletion polymorphism of the angiotensin-converting enzyme gene and loss of the insertion allele in aldosterone-producing adenoma

The genetic mechanisms responsible for the formation of adrenocortical adenomas which autonomously produce aldosterone are largely unknown. The adrenal renin-angiotensin system has been implicated in the pathophysiology of these tumours. Angiotensin-converting enzyme (ACE) catalyses the generation of angiotensin II, and the insertion/deletion (I/D) polymorphism of the ACE gene regulates up to 50% of plasma and cellular ACE variability in humans. We therefore examined the genotypic and allelic frequency distributions of the ACE gene I/D polymorphism in 55 patients with aldosterone-producing adenoma, APA, (angiotensin-unresponsive APA n = 28, angiotensin-responsive APA n = 27), and 80 control subjects with no family history of hypertension. We also compared the ACE gene I/D polymorphism allelic pattern in matched tumour and peripheral blood DNA in the 55 patients with APA. The frequency of the D allele was 0.518 and 0.512 and the I allele was 0.482 and 0.488 in the APA and control subjects respectively. Genotypic and allelic frequency analysis found no significant differences between the groups. Examination of the matched tumour and peripheral blood DNA samples revealed the loss of the insertion allele in four of the 25 patients who were heterozygous for the ACE I/D genotype. The I/D polymorphism of the ACE gene does not appear to contribute to the biochemical and phenotypic characteristic of APA, however, the deletion of the insertion allele of the ACE gene I/D polymorphism in 16% of aldosterone-producing adenomas may represent the loss of a tumour suppressor gene/s or other genes on chromosome 17q which may contribute to tumorigenesis in APA.

Anaplasma marginale: detection of carrier cattle by PCR-ELISA

A highly sensitive and specific polymerase chain reaction (PCR) based assay for the detection of the minute levels of Anaplasma marginale present in the blood of long-term carrier cattle was developed. A simple lysis method was used to remove most of the haemoglobin from the blood to facilitate direct input of samples into the PCR reactions without prior purification of the DNA. PCR product was detected by enzyme-linked immunosorbent assay (ELISA) to simplify the processing of large numbers of samples. The sensitivity limit of the PCR-ELISA was 0.00015% parasitaemia (24 infected erythrocytes per microlitre of blood). No cross-reactivity of the assay was observed when A. marginale-negative blood infected with Babesia bovis or Theileria orientalis was tested. The PCR-ELISA was shown to be 92% efficient in the detection of long-term A. marginale carrier cattle. No false-positive results were obtained. These results compared favourably with 2 serological assays for detection of A. marginale carrier cattle (card agglutination test and ELISA) which were applied to the same experimental animals.

Different allelic patterns at chromosome 11q13 in paired aldosterone-producing tumours and blood DNA

1. We previously reported loss of heterozygosity (LOH) at region q13 of chromosome 11 in five aldosterone-producing tumours (APT) using restriction fragment length polymorphism (RFLP) analysis, including two from patients with familial hyperaldosteronism. 2. In the present study, microsatellite markers were used to examine 33 informative paired blood and tumour DNA samples from patients with APT for LOH at three loci that map to chromosome 11q13. 3. LOH at one or more loci was detected in seven (21.2%) tumour DNA samples. 4. This study provides further support that mutations at 11q13 may be involved in the underlying pathophysiology of aldosterone-producing tumours of the adrenal cortex.

Anaplasma marginale: failure of sera from immune cattle to confer protection in passive-transfer experiments

High levels of immunity to Anaplasma marginale were induced in cattle either by vaccination using sonically disrupted A. marginale-infected erythrocytes or by repeated infection with different strains of the rickettsia. In both instances, high levels of anti-A. marginale antibody were detected in the sera of the immune cattle by immunoblotting. Serum from one animal that had been made immune by repeated infection was transferred intravenously to A. marginale-susceptible calves (three non-splenectomised and two splenectomised) undergoing initial A. marginale infection at serum doses of 2-10 ml/kg. Neither the course nor the outcome of infection as indicated by the parasite levels attained or the level of anaemia induced was altered in the calves that received the immune serum relative to the course or outcome of infection in control calves (two non-splenectomised and two splenectomised) that received serum from an two splenectomised) that received serum from an A. marginale-naive donor animal. In a similar experiment, a pool of sera from four steers that had been vaccinated with sonically disrupted A. marginale initial bodies was transfused into two intact A. marginale-susceptible calves during the early stage of A. marginale infection at a dose of 10 ml/kg. No difference was observed in the course or outcome of infection in these calves relative to the course or outcome of infection in the two non-splenectomised calves that were transfused with non-immune serum.(ABSTRACT TRUNCATED AT 250 WORDS)