Incorporating mutational heterogeneity to identify genes that are enriched for synonymous mutations in cancer

BACKGROUND

Synonymous mutations, which change the DNA sequence but not the encoded protein sequence, can affect protein structure and function, mRNA maturation, and mRNA half-lives. The possibility that synonymous mutations might be enriched in cancer has been explored in several recent studies. However, none of these studies control for all three types of mutational heterogeneity (patient, histology, and gene) that are known to affect the accurate identification of non-synonymous cancer-associated genes. Our goal is to adopt the current standard for non-synonymous mutations in an investigation of synonymous mutations.

RESULTS

Here, we create an algorithm, MutSigCVsyn, an adaptation of MutSigCV, to identify cancer-associated genes that are enriched for synonymous mutations based on a non-coding background model that takes into account the mutational heterogeneity across these levels. Using MutSigCVsyn, we first analyzed 2572 cancer whole-genome samples from the Pan-cancer Analysis of Whole Genomes (PCAWG) to identify non-synonymous cancer drivers as a quality control. Indicative of the algorithm accuracy we find that 58.6% of these candidate genes were also found in Cancer Census Gene (CGC) list, and 66.2% were found within the PCAWG cancer driver list. We then applied it to identify 30 putative cancer-associated genes that are enriched for synonymous mutations within the same samples. One of the promising gene candidates is the B cell lymphoma 2 (BCL-2) gene. BCL-2 regulates apoptosis by antagonizing the action of proapoptotic BCL-2 family member proteins. The synonymous mutations in BCL2 are enriched in its anti-apoptotic domain and likely play a role in cancer cell proliferation.

CONCLUSION

Our study introduces MutSigCVsyn, an algorithm that accounts for mutational heterogeneity at patient, histology, and gene levels, to identify cancer-associated genes that are enriched for synonymous mutations using whole genome sequencing data. We identified 30 putative candidate genes that will benefit from future experimental studies on the role of synonymous mutations in cancer biology.

How soluble misfolded proteins bypass chaperones at the molecular level

Subpopulations of soluble, misfolded proteins can bypass chaperones within cells. The extent of this phenomenon and how it happens at the molecular level are unknown. Through a meta-analysis of the experimental literature we find that in all quantitative protein refolding studies there is always a subpopulation of soluble but misfolded protein that does not fold in the presence of one or more chaperones, and can take days or longer to do so. Thus, some misfolded subpopulations commonly bypass chaperones. Using multi-scale simulation models we observe that the misfolded structures that bypass various chaperones can do so because their structures are highly native like, leading to a situation where chaperones do not distinguish between the folded and near-native-misfolded states. More broadly, these results provide a mechanism by which long-time scale changes in protein structure and function can persist in cells because some misfolded states can bypass components of the proteostasis machinery.

The role of migration in mutant dynamics in fragmented populations

Mutant dynamics in fragmented populations have been studied extensively in evolutionary biology. Yet, open questions remain, both experimentally and theoretically. Some of the fundamental properties predicted by models still need to be addressed experimentally. We contribute to this by using a combination of experiments and theory to investigate the role of migration in mutant distribution. In the case of neutral mutants, while the mean frequency of mutants is not influenced by migration, the probability distribution is. To address this empirically, we performed in vitro experiments, where mixtures of GFP-labelled ("mutant") and non-labelled ("wid-type") murine cells were grown in wells (demes), and migration was mimicked via cell transfer from well to well. In the presence of migration, we observed a change in the skewedness of the distribution of the mutant frequencies in the wells, consistent with previous and our own model predictions. In the presence of de novo mutant production, we used modelling to investigate the level at which disadvantageous mutants are predicted to exist, which has implications for the adaptive potential of the population in case of an environmental change. In panmictic populations, disadvantageous mutants can persist around a steady state, determined by the rate of mutant production and the selective disadvantage (selection-mutation balance). In a fragmented system that consists of demes connected by migration, a steady-state persistence of disadvantageous mutants is also observed, which, however, is fundamentally different from the mutation-selection balance and characterized by higher mutant levels. The increase in mutant frequencies above the selection-mutation balance can be maintained in small ( N < N c ) demes as long as the migration rate is sufficiently small. The migration rate above which the mutants approach the selection-mutation balance decays exponentially with N / N c . The observed increase in the mutant numbers is not explained by the change in the effective population size. Implications for evolutionary processes in diseases are discussed, where the pre-existence of disadvantageous drug-resistant mutant cells or pathogens drives the response of the disease to treatments.

Vascularized pancreas-on-a-chip device produced using a printable simulated extracellular matrix

The extracellular matrix (ECM) influences cellular behavior, function, and fate. The ECM surrounding Langerhans islets has not been investigated in detail to explain its role in the development and maturation of pancreatic β-cells. Herein, a complex combination of the simulated ECM (sECM) has been examined with a comprehensive analysis of cell response and a variety of controls. The most promising results were obtained from group containing fibrin, collagen type I, Matrigel®, hyaluronic acid, methylcellulose, and two compounds of functionalized, ionically crosslinking bacterial cellulose (sECMbc). Even though the cell viability was not significantly impacted, the performance of group of sECMbc showed 2 to 4x higher sprouting number and length, 2 to 4x higher insulin secretion in static conditions, and 2 to 10x higher gene expression of VEGF-A, Endothelin-1, and NOS3 than the control group of fibrin matrix (sECMf). Each material was tested in a hydrogel-based, perfusable, pancreas-on-a-chip device and the best group - sECMbc has been tested with the drug Sunitinib to show the extended possibilities of the device for both diabetes-like screening as well as PDAC chemotherapeutics screening for potential personal medicine approach. It proved its functionality in 7 days dynamic culture and is suitable as a physiological tissue model. Moreover, the device with the pancreatic-like spheroids was 3D bioprintable and perfusable.

Abstract B014: Massively parallel functional assessment of label-free mutant pools is a universal approach to parametrize mechanistic models of drug resistance evolution

Systematically scanning the effects of amino acid substitutions across a protein is a powerful technique in protein engineering, synthetic biology, and the study of drug resistance. In general, these selection experiments increase growth rates to select for mutants. Current methods use molecular barcodes to circumvent the resolution barriers imposed by conventional NGS sequencing of point mutations in mutant pools. Barcodes introduce synonymous mutations in the genome and assume neutrality, but it is now well accepted that synonymous mutations affect protein function. In a different approach, barcodes on cDNA constructs require a cumbersome second cloning step during library generation. We describe an approach that harnesses a highly sensitive duplex sequencing strategy to skip this barcode integration step and directly measure the target in label-free deep mutant pools. Furthermore, we employ the use of single-mutant standards with well-studied growth dynamics. By tracking the deviations from the expected growth trajectory of these mutant standards, we correct for dose-response variations that often result in low replicate agreement in these functional screens. Our workflow is compatible with any pool generation strategy, and the parameters that we obtain are robust enough to be useful in detailed models of cellular dynamics in synthetic biology studies. We developed a method for the functional assessment of deep mutant pools in a single pooled experiment. The workflow includes generating a label-free library of mutants at a desired target and sequencing the mutagenized pool before and during drug treatment using duplex sequencing. We demonstrate our pooled approach by focusing on target-driven resistance in Chronic Myeloid Leukemia (CML). To this end, we studied the 17 most clinically abundant BCRABL resistant mutations in imatinib refractory CML at low frequencies of 1 in 15,000. The sensitivity afforded by duplex sequencing enabled the accurate quantification of growth rates of these mutants under imatinib selection, with all 17 mutants closely matching their expected growth trajectory as predicted by individual dose-response studies. Moreover, we use an inference-based approach that uses hill-curve information from our mutant standards to detect slight variations in attempted dose between pooled replicates. Correcting for these slight variations in attempted dose leads to a &gt;10-fold improvement in replicate agreement. Here, we demonstrate a fast, label-free workflow that achieves high levels of sensitivity and specificity in measuring growth dynamics of deep mutant pools. Importantly, our method does not rely on synonymous, potentially error-inducing labels. Given recent successes in deep learning that predict structure and function in proteins, our approach can be used to generate large training sets of mutation-drug phenotypes. Predicting the rich phenotypic data generated using existing sequence and structural data could dramatically reduce the experiments that are necessary to generate predictive information on drug resistance.

Citation Format: Haider Inam, Scott Leighow, Justin Pritchard. Massively parallel functional assessment of label-free mutant pools is a universal approach to parametrize mechanistic models of drug resistance evolution [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr B014.

A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Is photosynthetic enhancement sustained through three years of elevated CO2 exposure in 175-year-old Quercus robur?

Current carbon cycle models attribute rising atmospheric CO2 as the major driver of the increased terrestrial carbon sink, but with substantial uncertainties. The photosynthetic response of trees to elevated atmospheric CO2 is a necessary step, but not the only one, for sustaining the terrestrial carbon uptake, but can vary diurnally, seasonally and with duration of CO2 exposure. Hence, we sought to quantify the photosynthetic response of the canopy-dominant species, Quercus robur, in a mature deciduous forest to elevated CO2 (eCO2) (+150 μmol mol-1 CO2) over the first 3 years of a long-term free air CO2 enrichment facility at the Birmingham Institute of Forest Research in central England (BIFoR FACE). Over 3000 measurements of leaf gas exchange and related biochemical parameters were conducted in the upper canopy to assess the diurnal and seasonal responses of photosynthesis during the 2nd and 3rd year of eCO2 exposure. Measurements of photosynthetic capacity via biochemical parameters, derived from CO2 response curves, (Vcmax and Jmax) together with leaf nitrogen concentrations from the pre-treatment year to the 3rd year of eCO2 exposure, were examined. We hypothesized an initial enhancement in light-saturated net photosynthetic rates (Asat) with CO2 enrichment of ≈37% based on theory but also expected photosynthetic capacity would fall over the duration of the study. Over the 3-year period, Asat of upper-canopy leaves was 33 ± 8% higher (mean and standard error) in trees grown in eCO2 compared with ambient CO2 (aCO2), and photosynthetic enhancement decreased with decreasing light. There were no significant effects of CO2 treatment on Vcmax or Jmax, nor leaf nitrogen. Our results suggest that mature Q. robur may exhibit a sustained, positive response to eCO2 without photosynthetic downregulation, suggesting that, with adequate nutrients, there will be sustained enhancement in C assimilated by these mature trees. Further research will be required to understand the location and role of the additionally assimilated carbon.

Multiple screening approaches reveal HDAC6 as a novel regulator of glycolytic metabolism in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer without a targeted form of therapy. Unfortunately, up to 70% of patients with TNBC develop resistance to treatment. A known contributor to chemoresistance is dysfunctional mitochondrial apoptosis signaling. We set up a phenotypic small-molecule screen to reveal vulnerabilities in TNBC cells that were independent of mitochondrial apoptosis. Using a functional genetic approach, we identified that a "hit" compound, BAS-2, had a potentially similar mechanism of action to histone deacetylase inhibitors (HDAC). An in vitro HDAC inhibitor assay confirmed that the compound selectively inhibited HDAC6. Using state-of-the-art acetylome mass spectrometry, we identified glycolytic substrates of HDAC6 in TNBC cells. We confirmed that inhibition or knockout of HDAC6 reduced glycolytic metabolism both in vitro and in vivo. Through a series of unbiased screening approaches, we have identified a previously unidentified role for HDAC6 in regulating glycolytic metabolism.

Identification of genes required for Mycobacterium abscessus growth in vivo with a prominent role of the ESX-4 locus

Mycobacterium abscessus, a rapidly growing mycobacterium (RGM) and an opportunistic human pathogen, is responsible for a wide spectrum of clinical manifestations ranging from pulmonary to skin and soft tissue infections. This intracellular organism can resist the bactericidal defense mechanisms of amoebae and macrophages, an ability that has not been observed in other RGM. M. abscessus can up-regulate several virulence factors during transient infection of amoebae, thereby becoming more virulent in subsequent respiratory infections in mice. Here, we sought to identify the M. abscessus genes required for replication within amoebae. To this end, we constructed and screened a transposon (Tn) insertion library of an M. abscessus subspecies massiliense clinical isolate for attenuated clones. This approach identified five genes within the ESX-4 locus, which in M. abscessus encodes an ESX-4 type VII secretion system that exceptionally also includes the ESX conserved EccE component. To confirm the screening results and to get further insight into the contribution of ESX-4 to M. abscessus growth and survival in amoebae and macrophages, we generated a deletion mutant of eccB4 that encodes a core structural element of ESX-4. This mutant was less efficient at blocking phagosomal acidification than its parental strain. Importantly, and in contrast to the wild-type strain, it also failed to damage phagosomes and showed reduced signs of phagosome-to-cytosol contact, as demonstrated by a combination of cellular and immunological assays. This study attributes an unexpected and genuine biological role to the underexplored mycobacterial ESX-4 system and its substrates.

Abstract C56: Platinum containing anti-cancer agents as targeted therapeutics

Cisplatin and its analogs are one of the most widely used family of cancer chemotherapeutics. However, despite a diverse array of analogs having been synthesized over the past decades, the underlying assumption has been that they all work similarly by damaging DNA. Utilizing a unique multi-platform genetic approach we show that this is not the case, and that small modifications to the core structure of cisplatin can produce unexpected changes in mechanism of action. Specifically, we found oxaliplatin and a subset of mono-functional cisplatin analogs closely resembled transcription and translation inhibitors. This set of platinum-based agents do not rely on traditional cisplatin repair and tolerance pathways such as nucleotide excision repair, homologous recombination and inter-strand cross-link repair. Instead, we've demonstrated oxaliplatin treatment kills cells by eliciting a ribosome biogenesis stress response. Additionally, across a panel of human cell lines, we've shown that higher expression of ribosomal proteins correlates with resistance to these transcription/translation inhibitor-like platinum agents. From this analysis, and by analyzing and comparing human patient tumor expression data, we've concluded that oxaliplatin treatment is best applied in tumors that have developed a heightened dependence on translation. Thus, while commonly regarded as “blunt weapons”, our current arsenal of genotoxic anti-cancer agents utilizes surprisingly diverse mechanisms that suggest new paradigms for their application in patients.

Citation Format: Peter M. Bruno, Ga Young Park, Junko Murai, Yunpeng Liu, Justin Pritchard, Yves Pommier, Stephen J. Lippard, Michael T. Hemann. Platinum containing anti-cancer agents as targeted therapeutics. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C56.

Offering statins to a population attending health checks with a 10-year cardiovascular disease risk between 10% and 20

BACKGROUND

In 2014 the UK National Institute for Health and Care Excellence recommended reducing the threshold for offering statin therapy to patients from a 10-year modelled risk of cardiovascular disease (CVD) of 20% to 10%.

AIM

To describe the response of patients in UK primary care with a CVD risk between 10% and 20% to an invitation to attend a consultation to discuss statins.

DESIGN AND SETTING

Review of electronic medical records at one GP practice in the East of England.

METHOD

We invited all patients who had attended an NHS Health Check at the practice, had a QRisk(®) score between 10% and 20%, and were not prescribed statins to attend designated clinics in the practice to discuss starting statins. We reviewed the medical records to identify those who had attended the clinics and those who had chosen to start a statin.

RESULTS

Of 410 patients invited, 100 (24.4%) patients attended the designated clinics and 45 (11%) chose to start a statin. Those who chose to start a statin were older and with a higher QRisk(®) than those who did not. Among those who attended, individuals who started a statin had a higher QRisk(®) than those who did not and were more likely to be current or ex-smokers.

CONCLUSIONS

The proportion choosing to start a statin was substantially lower than previously estimated. Large population-based studies with long-term follow-up are needed to assess the impact on health and workload of this change in guidance.

Abstract 3597: EZH2 D1 domain mutants confer acquired resistance to EZH2-targeted inhibitors and reprogram B-cell transcription

Aberrant epigenetic changes play an important role in the onset and progression of numerous tumor types, and targeting enzymes that regulate these processes holds significant promise for cancer treatment. The identification of Y641 and A677 oncogenic mutations in the histone methyl-transferase EZH2 in hematological cancers and melanoma, has led to a surge of interest in exploring the therapeutic potential of targeting EZH2. Several potent and selective small-molecule inhibitors targeting EZH2 (EZH2i) have recently been generated. The most advanced compounds, EPZ-6438 (E7438) and GSK126 (GSK2816126), are currently tested in lymphoma and advanced solid tumors, with EPZ-6438 exhibiting preliminary evidence of efficacy (ENA, 2014). As observed with other targeted cancer therapies, acquired resistance may pose a major clinical challenge to EZH2i. However, at this early stage in clinical development, mechanisms of acquired resistance to EZH2i remain unidentified. Nonetheless, it is critical to anticipate future clinical resistance mechanisms in order to develop effective patient treatment strategies.

To explore EZH2i resistance, we used an innovative forward genetic approach that combined a mutagenesis screen with next-generation sequencing technologies. Using this strategy, we identified a hotspot of EZH2 missense mutations (Y111 and I109) that conferred cross-resistance to both EPZ-6438 and GSK126. Surprisingly, the mutation hotspot lies outside the EZH2 catalytic region in its D1 domain, signifying a unique allosteric mechanism of drug resistance. Importantly, to drive resistance, the EZH2 mutants still required an active histone methyl-transferase catalytic domain and the main components of the polycomb repressive complex 2. Furthermore, we also uncovered an unexpected neomorphic role for these mutations in controlling the expression of genes typically involved in B-cell differentiation. This work describes the first evidence of acquired resistance to EZH2i, and identifies potential clinically relevant resistance mutations. Moreover, our findings provide new mechanistic insights into the function of EZH2, and importantly, suggest that acquired-resistance to EZH2i may arise in the clinic in a manner that remains targetable by inhibitors, thus, providing a foundation for the discovery of second-generation EZH2i to treat relapsed patients.

Citation Format: Francois Gonzalvez, Theresa Baker, Justin Pritchard, Victor M. Rivera, Andrew Garner. EZH2 D1 domain mutants confer acquired resistance to EZH2-targeted inhibitors and reprogram B-cell transcription. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3597. doi:10.1158/1538-7445.AM2015-3597

AtSUC2 has a role for sucrose retrieval along the phloem pathway: evidence from carbon-11 tracer studies

The location of the phloem within a plant, and its vulnerability to disruption, make it a difficult tissue to study and therefore non-invasive studies of phloem functionality are important. Here we compare, phloem transport, measured non-invasively, in wild type Arabidopsis thaliana, and transposon-insertion mutants for AtSUC1 or AtSUC2, giving in vivo information on the importance of these sucrose transporters for phloem transport. The suc2 mutant showed an increase in both phloem leakage and transport time, consistent with reduced sucrose uptake into both transport and collection phloem. The results are consistent with the AtSUC2 transporter being important for retrieval of leaked sucrose in the transport phloem of Arabidopsis. There was no difference in phloem transport properties between the wild type and the suc1 mutants, implying that the AtSUC1 transporter does not play a significant role within the transport phloem of Arabidopsis under the conditions of our study.

The roles of the cation transporters CHX21 and CHX23 in the development of Arabidopsis thaliana

The Arabidopsis thaliana genome encodes a family of 28 proteins whose members have been associated with the transport of monovalent cations across membranes. Experiments have been performed to elucidate the biochemical function and the role in plant development of two closely related members of this CHX family. A genotype carrying a knockout of the AtCHX23 gene (At1g05580) showed no phenotype when grown in glasshouse conditions. In particular, it did not exhibit the reduced root growth phenotype observed for a knockout of its homologue AtCHX21 when exposed to elevated sodium concentration. However, it was not possible to produce plants that were homozygous knockout for both AtCHX21 and AtCHX23. Reverse transcription-PCR (RT-PCR) experiments revealed that both genes are highly expressed in flower buds, flowers, and pollen. However, examination of pollen grain viability and pollen tube growth through excised styles did not reveal a phenotypic difference between the chx21(-)chx23(-) condition and other haplotypes. Crosses between selected mutants and wild-type plants in which the chx21(-)chx23(-) haplotype was produced by either the male or female parent demonstrated unequivocally that the chx21(-)chx23(-) haplotype could not pass through the female line. This suggests that the genes share a critical function in the development and/or function of the female gametophyte and that this function cannot be provided by other members of the AtCHX gene family. Experiments were carried out using the heterologous expression of AtCHX23 in Saccharomyces cerevisiae genotypes carrying combinations of deletions of genes involved in the transport of sodium or potassium across membranes. The results show that CHX23 would only complement the poor colony growth phenotype associated with the deletion of the yeast gene kha1. The conclusion is that both AtCHX21 and AtCHX23 act in potassium homeostasis within the female gametophyte and this is discussed in terms of the diversification of gene sequence and function within the CHX gene family.

A sublethal dose of thiamethoxam causes a reduction in xylem feeding by the bird cherry-oat aphid (Rhopalosiphum padi), which is associated with dehydration and reduced performance

The active ingestion of xylem sap by aphids is hypothesised to be an important mechanism for rehydration. When starved bird cherry-oat aphids (Rhopalosiphum padi) were allowed to feed on wheat (Triticum aestivum) treated with a sublethal dose of the xylem-mobile neonicotinoid thiamethoxam, analysis of feeding behaviours using the electrical penetration graph revealed a reduction in xylem feeding that was reversed on removal of the toxin. To test the importance of xylem-feeding behaviour as a rehydration mechanism, the effects of the sublethal dose of thiamethoxam on aphid water content, honeydew excretion, growth and fecundity were investigated. Body water contents of starved R. padi feeding on wheat treated with thiamethoxam were significantly reduced compared to aphids feeding on wheat treated with distilled water (74.5+/-0.23 and 75.6+/-0.18%, respectively). In addition, the sublethal dose of thiamethoxam had detrimental effects on aphid performance. At reproductive maturity, aphids that had been born on wheat treated with thiamethoxam were significantly smaller (as measured by body plan area; 1.07+/-0.03mm(2)), lighter (0.31+/-0.04mg) and less fecund (2.85+/-0.36nymphs/day) than aphids born on wheat treated with distilled water (1.87+/-0.02mm(2), 0.72+/-0.03mg, 11.28+/-0.58nymphs/day, respectively). Regardless of whether the observed impairment of xylem feeding is due to a neurotoxic or an antifeedant effect, these results have important implications for commercial crop protection as the behaviour-modifying effects of the sublethal dose of thiamethoxam may change the efficacy of this pesticide throughout the growing season.

A water-specific aquaporin involved in aphid osmoregulation

The osmotic pressure of plant phloem sap is generally higher than that of insect body fluids. Water cycling from the distal to proximal regions of the gut is believed to contribute to the osmoregulation of aphids and other phloem-feeding insects, with the high flux of water mediated by a membrane-associated aquaporin. A putative aquaporin referred to as ApAQP1 was identified by RT-PCR of RNA isolated from the guts of pea aphids Acyrthosiphon pisum. The ApAQP1 protein has a predicted molecular mass 28.94kDa. Molecular modeling suggests that ApAQP1 has the general aquaporin topology and possesses the conserved pore properties of water-specific aquaporins. When expressed in Xenopus oocytes, ApAQP1 showed the hallmarks of aquaporin-mediated water transport, including an 18-fold increase in the osmotic water permeability of the oolemma, a reduced activation energy, and inhibition of elevated water transport activity by Hg ions. The ApAQP1 transcript was localised to the stomach and distal intestine, and RNAi-mediated knockdown of its expression resulted in elevated osmotic pressure of the haemolymph. Taken together, these data suggest that ApAQP1 contributes to the molecular basis of water cycling in the aphid gut.

pH and expansin action on single suspension-cultured tomato (Lycopersicon esculentum) cells

The aim of this study was to measure key material properties of the cell walls of single suspension-cultured plant cells and relate these to cell-wall biochemistry. To this end, micromanipulation was used to compress single tomato cells between two flat surfaces until they ruptured, and force-deformation data were obtained. In addition to measuring the bursting force, we also determined the elastic (Young's) modulus of the cell walls by matching low strain (< or = 20% deformation) experimental data with a cell compression model, assuming linear elastic cell walls. The walls were most elastic at pH 4.5, the pH optimum for expansin activity, with an elastic modulus of 2.0 +/- 0.1 GPa. Following the addition of exogenous expansins, cell walls became more elastic at all pH values. Western blot analysis of proteins from walls of cultured cells revealed the presence of expansin epitopes, suggesting that the inherent pH dependence of elasticity and other compression phenomena is related to the presence of endogenous expansin proteins and their wall-loosening ability. Although strict application of the linear-elastic model could not be applied to large deformations-for example, up to cell bursting-because of irreversible behaviour, the deviation of the data from the model was generally small enough to allow estimation of the strain in the cell wall at failure. This strain was greater at pH 4.5 and when expansins were added to the suspension. The changes in elasticity are consistent with suggestions about the mode of expansin action. The estimated strains at failure are compatible with data on the failure of Acetobacter-derived cellulose-xyloglucan composites and proposed mechanisms of such failure. Through the measurement of cell-wall material properties using micromanipulation, it may be possible to understand more fully how cell-wall composition, structure and biochemistry lead to cell mechanical behaviour.

Immune responses to myelin proteins in Guillain-Barré syndrome

BACKGROUND

Potential target autoantigens in the demyelinating form of Guillain-Barré syndrome (GBS) include the myelin proteins PMP22, P0 and P2.

METHODS

We investigated immunoreactivity to P0, P2 and PMP22 proteins in 37 patients with GBS and 32 healthy controls.

RESULTS

Antibodies to PMP22 or P0 peptides were detected at presentation in only 5 out of 37 patients. In ELISPOT assays, blood mononuclear cells from 15 out of 24 patients with GBS, but none of the control subjects, produced interleukin-10 (IL-10) in response to peptides from proteins P0, P2 or PMP22 (p = 0.0003). The cells from only two patients produced interferon-gamma (IFN gamma). The cells from 11 patients with GBS had increased IL-10 responses to peptides representing sequences from the extracellular domains of PMP22 before intravenous immunoglobulin (IVIg) treatment (p = 0.006). The cells from 11 patients with GBS, including 7 who responded to the extracellular domains of PMP22, had increased IL-10 responses to the intracellular domain of P0 before (p = 0.005) and those from 9 patients after they had been treated with IVIg (p = 0.01).

CONCLUSIONS

Antibodies to P0 and PMP22 protein peptides do occur in GBS but are uncommon. Circulating mononuclear cell IFN gamma responses to P0, P2 and PMP22 myelin protein peptides are rare, but IL-10 responses occur significantly more often than in normal subjects. They might be part of a harmful pathogenetic process or represent a regulatory response.

Exploring plant responses to aphid feeding using a full Arabidopsis microarray reveals a small number of genes with significantly altered expression

The aim of this study was to determine which Arabidopsis thaliana (L.) genes had significantly altered expression following 2-36 h of infestation by the aphid Myzus persicae (Sulzer). Six biological replicates were performed for both control and treatment at each time point, allowing rigorous statistical analysis of any changes. Only two genes showed altered expression after 2 h (one up- and one down-regulated) while two were down-regulated and twenty three were up-regulated at 36 h. The transcript annotation allowed classification of the significantly altered genes into a number of classes, including those involved in cell wall modification, carbon metabolism and signalling. Additionally, a number of genes were implicated in oxidative stress and defence against other pathogens. Five genes could not currently be assigned any function. The changes in gene expression are discussed in relation to current models of plant-insect interactions.

Liver cancer in European children: Incidence and survival, 1978–1997. Report from the Automated Childhood Cancer Information System project

Data on 849 children diagnosed with malignant hepatic tumours (International Classification of Childhood Cancer, Group VII) before the age of 15 years during 1978-1997 in Europe were extracted from the ACCIS database. Age-standardised incidence during 1988-1997 was 1.5 per million overall, 1.2 per million for hepatoblastoma and 0.2 per million for hepatic carcinoma. Over 90% of cases of hepatoblastoma occurred before age 5 years, whereas hepatic carcinoma had a fairly flat age distribution. Both tumours had an incidence in boys of 1.5-1.6 times that in girls. There were no significant time trends in incidence during 1978-1997. Five-year survival from hepatoblastoma diagnosed during 1988-1997 was 63% overall, and ranged from 52% in Eastern Europe to 84% in the North. Survival from hepatic carcinoma was much lower (37%). Between 1978-1982 and 1993-1997, 5-year survival (95% confidence interval (95% CI)) increased from 28% (95% CI 18-39) to 66% (95% CI 55-74) for hepatoblastoma and from 17% (95% CI 6-33) to 50% (95% CI 26-70) for hepatic carcinoma. These increases reflect the impact of advances in treatment of childhood liver cancer at a population level.

TheArabidopsis thaliana/Myzus persicaemodel system demonstrates that a single gene can influence the interaction between a plant and a sap-feeding insect

We have developed an Arabidopsis thaliana/Myzus persicae model system to allow the dissection of plant/insect interactions at a molecular genetic level. This allows the examination of the role of single plant genes in the interaction between the plant and an aphid. Our initial studies have exploited an Arabidopsis genotype in which the function of the amino acid transporter ANT1 has been abolished. This mutation results in a change in the proportions of several amino acids within the phloem sieve elements (SEs) resulting in an increase in the proportion of essential amino acids. This has been measured using aphid stylectomy to collect SE samples, followed by a novel micellar electrokinetic chromatography method for amino acid analysis. The SE content represents the aphid's diet, and use of electrical penetration graph technology and honeydew clocks have demonstrated that this altered diet results in a change in the feeding rate of the aphid. Balance sheets can be produced to show the amount (nmoles/24 h) of each of 18 amino acids taken up and excreted by aphids feeding on wild type and ant1 mutant plants. The data show that aphids feeding on the ant1 mutant take up larger amounts of amino acids. However, we could not detect any effect on the reproductive rate of the aphids. The results show that, under experimental conditions, this model system can be used to identify plant genes that control the behaviour and fecundity of an insect pest.

Sweet problems: insect traits defining the limits to dietary sugar utilisation by the pea aphid, Acyrthosiphon pisum

Plant phloem sap is an extreme diet for animals, partly because of its high and variable sugar content. The physiological and feeding traits of the pea aphid Acyrthosiphon pisum that define the upper and lower limits to the range of dietary sucrose concentrations utilised by this insect were determined principally using chemically defined diets containing 0.125-1.5 mol l(-1) sucrose. On the diets with 0.125 mol l(-1) and 1.5 mol l(-1) sucrose, the aphids died as larvae within 8 and 14 days of birth, respectively. On the other diets, 60-96% of aphids developed to adulthood, and the 0.5 mol l(-1) and 0.75 mol l(-1) diets supported the highest fecundity. The diet with 0.125 mol l(-1) sucrose was ingested at 36% of the rate of the 0.25 mol l(-1) sucrose diet, but >90% of ingested sucrose-carbon was assimilated on both diets. This suggests that the lower limit is dictated by the aphid feeding response, specifically, a requirement for a minimal concentration of sucrose for sustained feeding. The haemolymph osmotic pressure of aphids on diets with 0.125-1.5 mol l(-1) sucrose was up to 68% higher than on 0.125-1.0 mol l(-1) sucrose diets, but diet consumption and sucrose-carbon assimilation was not reduced on the very high sucrose diets relative to 1.0 mol l(-1) sucrose. This suggests that failure of the osmoregulatory capacity of the insects on high sucrose diets may define the upper limit to the range of dietary sucrose utilised by the aphids. The mean haemolymph osmotic pressure of aphids on plants with phloem sap containing 0.37-0.97 mol l(-1) sucrose was 1.61+/-0.063 MPa (mean +/- s.e.m.), not significantly different from that (1.47+/-0.059 MPa) on diets with 0.25-1.0 mol l(-1) sucrose. It is concluded that the osmoregulatory response of aphids to diets and plants are comparable, and, more generally, that the feeding and osmoregulatory capabilities of the aphids are compatible with the phloem sugar levels commonly encountered by aphids feeding on plants.

A phloem-enriched cDNA library from Ricinus: insights into phloem function

The aim of this study was to identify genes that are expressed in the phloem. Increased knowledge of phloem regulation will contribute to our understanding of its many roles, from transport of solutes to information about interactions with pathogens. A cDNA library constructed from phloem-enriched sap exuding from cut Ricinus communis (L.) hypocotyls was sequenced. To assess contamination from other tissues, two libraries were constructed: one using the first 15 min of exudation and the other from sap collected after 120 min of exudation had elapsed. Of 1012 clones sequenced, 158 unique transcripts were identified. The presence of marker molecules such as profilin, the low occurrence of chloroplast-related mRNAs, and the sieve element localization of constituent mRNA using in situ hybridization were consistent with a phloem origin of the sap. Functional analysis of the cDNAs revealed classifications including ribosomal function, interaction with the environment, transport, DNA/RNA binding, and protein turnover. An analysis of the closest Arabidopsis thaliana (L.) homologue for each clone indicated that genes involved in cell localization, protein synthesis, tissue localization, organ localization, organ differentiation, and cell fate were represented at twice the level occurring in the whole Arabidopsis genome. The transcripts found in this phloem-enriched library are discussed in the context of phloem function and the relationship between the companion cell and sieve element.

Functional analysis of CHX21: a putative sodium transporter in Arabidopsis

The functional role of CHX21, a member of the Arabidopsis thaliana CHX cation transporter family, has been investigated in plants growing under "ideal" conditions and in the presence of elevated NaCl levels. In public databases, AtCHX21 (At2g31910) is annotated as a putative Na+/H+ antiporter. In this study, Southern analysis was used to identify a genotype that contained a single transposon insertion within its genome; using PCR, this insertion was shown to be within the CHX21 locus. No CHX21 transcript was detectable in Atchx21 (mutant) plants using RT-PCR. In the absence of salt stress, Atchx21 showed significant quantitative differences from the wild type (AtCHX21) in development with respect to characters such as rosette width and flowering time. In the presence of 50 mM NaCl, (i) roots of Atchx21 elongated more slowly than the wild type, (ii) the leaf sap Na+ concentration was significantly lower in Atchx21 compared with the wild type, and (iii) the concentra) in the xylem was lower compared with the wild type. The concentration of Na+ exported from the leaf in the phloem was unchanged. Thus, loading of Na+ into the root xylem could explain changes in leaf concentration of Na+. This hypothesis was supported by immunolocalization which demonstrated that the AtCHX21 transporter could only be detected in root endodermal cells. Immunogold labelling of ultra-thin sections, followed by transmission electron microscopy, demonstrated the localization of the protein in the plasma membrane. The data demonstrate that the CHX21 transporter may play a role in regulation of xylem Na+ concentration and, consequently, Na+ accumulation in the leaf.

The significance of gut sucrase activity for osmoregulation in the pea aphid, Acyrthosiphon pisum

The osmotic pressure of the body fluids of aphids is lower than in their diet of plant phloem sap. It is hypothesised that aphids reduce the osmotic pressure of ingested food by sucrase-mediated hydrolysis of dietary sucrose to glucose and fructose, and the polymerisation of glucose into oligosaccharides of low osmotic pressure per hexose unit. To test this hypothesis, the impact of the alpha-glucosidase inhibitor acarbose on the sugar relations and osmoregulation of aphids was explored. Acarbose inhibited sucrase activity in gut homogenates and the production of monosaccharides and oligosaccharides in the honeydew of live aphids. Acarbose caused an increase in the haemolymph osmotic pressure for aphids reared on a diet (containing 0.75 M sucrose) hyperosmotic to the haemolymph and not on the isoosmotic diet containing 0.2 M sucrose. It did not affect aphid feeding rate over 2 days, except at high concentrations on 0.75 M sucrose diet, and this may have been a secondary consequence of osmotic dysfunction. Acarbose-treated aphids died prematurely. With 5 microM dietary acarbose, mean survivorship on 0.2 M sucrose diet was 4.2 days, not significantly different from starved aphids, indicating that, although these aphids fed, they were deprived of utilisable carbon; and on 0.75 M sucrose diet, mean survivorship was just 2.8 days, probably as a consequence of osmotic failure. It is concluded that the aphid gut sucrase activity is essential for osmoregulation of aphids ingesting food hyperosmotic to their body fluids.

Exercise for people with peripheral neuropathy

BACKGROUND

Peripheral neuropathies are a wide range of diseases affecting the peripheral nerves. Demyelination or axonal degeneration gives rise to a variety of symptoms including reduced or altered sensation, pain, muscle weakness and fatigue. Secondary disability arises and this may result in adjustments to psychological and social function. Exercise therapy, with a view to developing strength and stamina, forms part of the treatment for people with peripheral neuropathy, particularly in the later stages of recovery from acute neuropathy and in chronic neuropathies.

OBJECTIVES

The primary objective was to examine the effect of exercise therapy on functional ability in the treatment of people with peripheral neuropathy. In addition, secondary outcomes of muscle strength, endurance, broader measures of health and well being, as well as unfavourable outcomes were examined.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group register (July 2002 and updated February 2004) and MEDLINE (from January 1966 to June 2004), EMBASE (from January 1980 to June 2004), CINAHL (from January 1982 to July 2002) and LILACS (from January 1982 to July 2002) electronic databases. Bibliographies of all selected randomised controlled trials were checked and authors contacted to identify additional published or unpublished data.

SELECTION CRITERIA

Any randomised or quasi-randomised controlled trial comparing the effect of exercise therapy with no exercise therapy or drugs or an alternative non-drug treatment on functional ability (or disability) in people with peripheral neuropathy at least eight weeks after randomisation was included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected eligible studies, rated the methodological quality and extracted data.

MAIN RESULTS

Only one trial fully met the inclusion criteria. An additional two trials assessed outcomes less than eight weeks after randomisation and were also included. Methodological quality was poor for several criteria in each study. Data used in the three studies could not be pooled due to heterogeneity of diagnostic groups and outcome measures. The results of the included trials failed to show any effect of strengthening and endurance exercise programmes on functional ability in people with peripheral neuropathy. However, there is some evidence that strengthening exercise programmes were moderately effective in increasing the strength of tested muscles.

REVIEWERS' CONCLUSIONS

There is inadequate evidence to evaluate the effect of exercise on functional ability in people with peripheral neuropathy. The results suggest that progressive resisted exercise may improve muscle strength in affected muscles.

Haemophilus influenzae as a possible cause of Guillain–Barré syndrome

Recent reports have contained conflicting results on the relationship between antecedent Haemophilus influenzae infection and Guillain-Barré syndrome (GBS). To investigate the prevalence of H. influenzae infection in GBS patients in a British population, we carried out a retrospective study with 62 consecutive GBS patients and 63 normal controls of similar age and sex. Whole bacteria of both encapsulated and nonencapsulated strains of H. influenzae were employed as antigens in an enzyme-linked immunosorbent assay (ELISA) for anti-H. influenzae IgG, IgM and IgA antibodies. Elevated antibodies of two or three classes were found in one GBS patient and none in the normal controls. Six GBS patients had IgG antibodies against nonencapsulated H. influenzae compared with only one in the normal control group (p=0.06). Western blot for IgG antibody showed that all the sera with IgG antibodies recognized the lipopolysaccharide (LPS) of both strains of H. influenzae. Antiganglioside GM1 antibody was not associated with anti-H. influenzae antibody in our study. Absorption with encapsulated or nonencapsulated H. influenzae, Campylobacter jejuni and Escherichia coli before testing on Western blot showed that only nonencapsulated H. influenzae absorbed the anti-LPS antibodies. In conclusion, there is a possible but rare association of GBS with nonencapsulated H. influenzae in the UK.

Outcome of patients with stage III or inoperable WT treated on the second United Kingdom WT protocol (UKWT2); a United Kingdom Children's Cancer Study Group (UKCCSG) study

BACKGROUND

The aims of UKWT2 included consolidating the results for stage III patients obtained in UKWT1 and improving the outcome for patients with inoperable tumours by giving vincristine, actinomycin-D and doxorubicin in an intensive schedule (Intensive AVA).

PROCEDURE

The second UK WT trial (UKWT2) ran between July 1986 and September 1991 accruing 448 patients. One hundred and six patients were diagnosed and treated for stage III disease. Six had clear cell sarcoma of the kidney (CCSK) and seven had rhabdoid tumours of the kidney (RTK) and are analysed separately. One other patient was excluded from overall analysis. Ninety-two patients were followed for a median of 115 months. Seventy-five received standard chemotherapy and abdominal radiotherapy according to protocol. Seventeen had stage III disease at immediate nephrectomy, but radiotherapy was omitted by physician choice. Thirty-three patients had inoperable disease at diagnosis and received pre-nephrectomy chemotherapy.

RESULTS

Overall survival (OS) at 4 years for stage III favourable histology (FH) patients receiving abdominal RT was 83% (CI: 73-89). For children with stage III disease in whom RT was omitted the OS was 82% (CI: 59-97) and for inoperable disease 94% (CI: 78-98). The overall and event-free survival (EFS) of children with stage III CCSK was 100% and was achieved with the majority of patients not receiving radiotherapy (CI: 48-100). Three of seven children with RTK are alive EFS and OS 43% (CI: 10-73). For patients treated by abdominal radiotherapy the overall local control rate was 94.4% (CI: 86.4-98.5*%), 96.7% (CI: 88.5-99.6%) for flank RT and 83.3% (51.6-98.0%) for whole abdominal radiotherapy (WRT).

CONCLUSIONS

The outcome for stage III FH disease was similar to that reported for UKWT1 and NWTS-3. The combination of abdominal RT together with 3-drug chemotherapy achieves a high abdominal tumour control rate. Flank RT is probably sufficient for localised tumour rupture. The high cure rates for children in this trial with 'inoperable disease' suggests that treatment should be modified according to their post-chemotherapy stage in order to avoid over-treatment. The high OS for stage III CCSK on this protocol suggests that treatment duration could be curtailed and the role of RT reviewed, though the numbers are small. The prognosis for older children with RTK seems to be better than for younger children although larger studies are required to confirm this.

Risk-adapted treatment for childhood hepatoblastoma. final report of the second study of the International Society of Paediatric Oncology--SIOPEL 2

SIOPEL 2 was a pilot study designed to test the efficacy and toxicity of two chemotherapy (CT) regimens, one for patients with hepatoblastoma (HB) confined to the liver and involving no more than three hepatic sectors ('standard-risk (SR) HB'), and one for those with HB extending into all four sectors and/or with lung metastases or intra-abdominal extra hepatic spread 'high-risk (HR) HB'. SR-HB patients were treated with four courses of cisplatin (CDDP), at a dose of 80 mg/m(2) every 14 days, delayed surgery, and then two more similar CDDP courses. HR-HB patients were given CDDP alternating every 14 days with carboplatin (CARBO), 500 mg/m(2), and doxorubicin (DOXO), 60 mg/m(2). Two courses of CARBO/DOXO and one of CDDP were given postoperatively. Between October 1995 and May 1998, 77 SR-HB (10 of whom were actually treated with the HR protocol) and 58 HR-HB patients were registered and all 135 could be evaluated. Response rates for the entire SR-HB and HR-HB groups were 90% (95% CI 80-96%) and 78% (95% CI 65-87%), and resection rates were 97% (95% CI 87-99%) and 67% (95% CI 54-79%) including several children undergoing liver transplantation. For SR-HB patients, 3-year overall and progression-free survivals were 91% (+/-7%) and 89% (+/-7%) and for the HR-HB group 53% (+/-13%) and 48% (+/-13%), respectively. The short-term toxicity of these regimens was acceptable, with no toxic deaths. A treatment strategy based on CDDP monotherapy and surgery thus appears effective in SR-HB but, despite CT intensification, only half of the HR-HB patients are long-term survivors. For SR-HB patients, the efficacy of CDDP monotherapy and the CDDP/DOXO ('PLADO') combination are now being compared in a prospective randomised trial (SIOPEL 3).

Liver transplantation for hepatoblastoma: results from the International Society of Pediatric Oncology (SIOP) study SIOPEL-1 and review of the world experience

BACKGROUND

For hepatoblastoma (HB) that remains unresectable by partial hepatectomy after chemotherapy, total hepatectomy with orthotopic liver transplantation (LTX) has been advocated as the best treatment option. The role of LTX in the overall management of HB is still, however, unclear.

PROCEDURE

The results of LTX from the first study of HB by the International Society of Pediatric Oncology, SIOPEL-1, were analyzed. In addition, the world experience of LTX for HB was extensively reviewed. Twelve patients in the SIOPEL-1 study underwent a LTX. Median (range) follow-up at Dec. 31, 2001 was 117 months (52-125) since LTX.

RESULTS

Overall survival at 10 years post-LTX was 85% for the seven children who received a "primary LTX" and 40% for the 5 children who underwent a "rescue LTX" after previous partial hepatectomy. In the world experience (147 cases), the overall survival rate at 6 year post-LTX was 82% for 106 patients who received a "primary LTX" and 30% for 41 patients who underwent a "rescue LTX." Multivariate analysis of patients undergoing primary LTX showed that only macroscopic venous invasion had a significant impact (P-value: 0.045 with a hazard ratio of 2.96) on overall survival.

CONCLUSIONS

Orthotopic LTX has added a new dimension to the treatment of HB unresectable by partial hepatectomy. Because of the rarity of the disease and to optimize results, children with extensive HB should be treated in centers with surgical expertise in pediatric major liver resection and LTX, in close collaboration with pediatric oncologists, radiologists, and histopathologists.

A randomized controlled trial of recombinant interferon-beta 1a in Guillain-Barré syndrome

The authors recruited 19 nonambulant patients with Guillain-Barré syndrome into a pilot, double-blind, randomized, placebo-controlled safety trial of interferon beta 1a (IFN[beta]-1a) (Rebif). Participants received IFN[beta]-1a or placebo subcutaneously three times weekly, 22 microg for the first week and then 44 microg for up to 24 weeks, in addition to IV immunoglobulin (IVIg). IFN[beta] did not have any unexpected interaction with IVIg and there was no significant difference in rate of improvement.

Familial Hepatoblastoma and APC gene mutations: renewed call for molecular research

Recent findings have increased our understanding of the molecular mechanisms involved in the pathogenesis of hepatoblastoma and their relationship to the molecular pathology of familial adenomatous polyposis (FAP). Here, we describe hepatoblastoma in siblings who share a gene mutation for FAP inherited from their father. This observation confirms the link between these diseases and has implications for future molecular research. We also raise the question; should other members of 'at-risk' families be screened following a new diagnosis of either hepatoblastoma or FAP?

Successful treatment of empty follicle syndrome by triggering endogenous LH surge using GnRH agonist in an antagonist down-regulated IVF cycle

To date, empty follicle syndrome (EFS) has only been reported in GnRH agonist down-regulated IVF cycles. Some cases have been successfully treated by changing the batch, or by repeating the dose of hCG. A case of EFS was observed in both GnRH antagonist and GnRH agonist down-regulated IVF cycles when final oocyte maturation was triggered using urinary hCG (u-hCG). Failure to retrieve oocytes occurred, despite administration of a further dose of u-hCG from a different batch and a delayed repeated oocyte recovery performed in the second GnRH agonist down-regulated cycle. A successful oocyte recovery cycle was achieved after triggering of an endogenous gonadotrophin surge using GnRH agonist in an antagonist down-regulated cycle. Nine oocytes were readily retrieved from 10 follicles, at 36 h after GnRH agonist administration, and eight of these fertilized normally. Two good quality embryos were used for fresh transfer and four were cryopreserved for future use. EFS can occur in GnRH antagonist down-regulated IVF cycles, and can be successfully treated by triggering a natural gonadotrophin surge using GnRH agonist in the absence of any response to previous treatment methods. This represents a novel therapeutic modality for this uncommon but frustrating condition.

Apolipoprotein E genotypes and clinical outcome in Guillain-Barré syndrome

BACKGROUND

Polymorphism of the gene encoding the cholesterol transport protein apolipoprotein E (APOE, gene; apoE, protein), known to be involved in axonal regeneration and remyelination, influences outcome after a variety of central nervous system disorders. Apolipoprotein E gene polymorphisms could affect recovery from Guillain-Barré syndrome.

OBJECTIVE

To correlate APOE genotypes with residual disability and degree of improvement in Guillain-Barré syndrome, assessed one year after presentation

METHODS

91 patients with the syndrome were recruited from southeast England and their APOE genotypes were determined.

RESULTS

There were no clear differences in APOE genotype or allele frequencies when comparing the 91 patients with controls, nor when comparing 81 patients with good outcome and 10 with poor outcome.

CONCLUSIONS

APOE genotype did not influence susceptibility to Guillain-Barré syndrome or recovery from it. This may be because our sample size of 91 was not sufficiently large to detect small differences in recovery associated with different APOE genotypes, or because cholesterol transportation is not a crucial rate limiting step in peripheral nerve regeneration.