Spatial and temporal organization of the dominant frequencies in the fibrillating heart: body surface potential mapping in a rare case of sustained human ventricular fibrillation

AIMS

The aim of this study was to assess the spatial and temporal variability of dominant fibrillation frequencies in a rare case of sustained human ventricular fibrillation (VF).

METHODS AND RESULTS

Body surface potential mapping was performed in a patient with sustained VF and who was supported by a biventricular assist device. Dominant frequencies at 54 body sites were calculated from two recordings obtained 38 days apart. Variability of dominant frequencies between recordings and across body sites was quantified. Median dominant frequencies within recordings varied between 6.1 and 7.2 Hz in recording 1 and 5.6 and 6.6 Hz in recording 2, indicating a significant reduction in dominant frequencies between the recordings (P < 0.0001). Dominant frequencies differed across body sites by a mean (range) of 1.7 (0.4-2.8) Hz.

CONCLUSION

In this rare case of sustained VF, there was significant spatial and temporal variability of VF dominant frequencies. These findings should be considered in future ECG studies on VF where the spatial variability of dominant frequency might not otherwise have been considered.

The impact of a hybrid online and classroom-based course on palliative care competencies of family medicine residents

The University of Calgary offers a palliative care course that involves both classroom- and web-based learning for rural-based family medicine residents. This study assessed the impact of the course on palliative care-related competencies for two classes: 2004 and 2005. Instruments were developed to evaluate pre- versus post-course changes in knowledge (15-item quiz), attitudes (12-item survey), self-perceived comfort levels (19-item survey) and skills (3 long Objective Structured Clinical Examination stations (OSCEs), with accompanying standardised score sheets). In all, 16 and 20 residents participated in the 2004 and 2005 classes, respectively. Internal reliability values were acceptable to very good (Knowledge Quiz, Kuder-Richardson 20 = 0.5; Attitude Scale, alpha = 0.68-0.78; OSCE score sheets, alpha = 0.63-0.89; Self-Perceived Comfort Survey, alpha = 0.89-0.92). Inter-rater reliability values of the OSCE score sheets were alpha = 0.87 to 0.92. There was a significant improvement in the pre- versus post-course performances in OSCE 2 for 2004 and 2005 (P = 0.01; P = 0.01; d = 1.42 and 1.94, respectively). Despite statistically insignificant changes in the other OSCEs, acceptable to large effect sizes were noted (d = 0.4-1.34) for OSCE 1 in 2004 and OSCEs 3 in 2004 and 2005. Knowledge improved significantly pre-versus post-course in 2004 and 2005 (t = 4.44 and 8.99; d = 2.29 and 2.24, respectively). Significant improvements and large effect sizes were noted in the comfort scales, but a ceiling effect was noted in the communication subscale. This hybrid course resulted in significant improvements across four domains, knowledge, attitudes, self-perceived comfort scale, and skills, in 2 consecutive classes.

Closely linked cis-acting modifier of expansion of the CGG repeat in high risk FMR1 haplotypes

In its expanded form, the fragile X triplet repeat at Xq27.3 gives rise to the most common form of inherited mental retardation, fragile X syndrome. This high population frequency persists despite strong selective pressure against mutation-bearing chromosomes. Males carrying the full mutation rarely reproduce and females heterozygous for the premutation allele are at risk of premature ovarian failure. Our diagnostic facility and previous research have provided a large databank of X chromosomes that have been tested for the FRAXA allele. Using this resource, we have conducted a detailed genetic association study of the FRAXA region to determine any cis-acting factors that predispose to expansion of the CGG triplet repeat. We have genotyped SNP variants across a 650-kb tract centered on FRAXA in a sample of 877 expanded and normal X chromosomes. These chromosomes were selected to be representative of the haplotypic diversity encountered in our population. We found expansion status to be strongly associated with a ∼50-kb region proximal to the fragile site. Subsequent detailed analyses of this region revealed no specific genetic determinants for the whole population. However, stratification of chromosomes by risk subgroups enabled us to identify a common SNP variant which cosegregates with the subset of D group haplotypes at highest risk of expansion (, p=0.00002). We have verified that this SNP acts as a marker of repeat expansion in three independent samples. Hum Mutat 28(12), 1216–1224, 2007. © 2007 Wiley-Liss, Inc.

Clinical effectiveness and cost-effectiveness of laparoscopic surgery for colorectal cancer: systematic reviews and economic evaluation

OBJECTIVE

The aim of this study was to determine the clinical effectiveness and cost-effectiveness of laparoscopic, laparoscopically assisted (hereafter together described as laparoscopic surgery) and hand-assisted laparoscopic surgery (HALS) in comparison with open surgery for the treatment of colorectal cancer.

DATA SOURCES

Electronic databases were searched from 2000 to May 2005. A review of economic evaluations was undertaken by the National Institute for Health and Clinical Excellence in 2001. This review was updated from 2000 until July 2005.

REVIEW METHODS

Data from selected studies were extracted and assessed. Dichotomous outcome data from individual trials were combined using the relative risk method and continuous outcomes were combined using the Mantel-Haenszel weighted mean difference method. Summaries of the results from individual patient data (IPD) meta-analyses were also presented. An economic evaluation was also carried out using a Markov model incorporating the data from the systematic review. The results were first presented as a balance sheet for comparison of the surgical techniques. It was then used to estimate cost-effectiveness measured in terms of incremental cost per life-year gained and incremental cost per quality-adjusted life-year (QALY) for a time horizon up to 25 years.

RESULTS

Forty-six reports on 20 studies [19 randomised controlled trials (RCTs) and one IPD meta-analysis] were included in the review of clinical effectiveness. The RCTs were of generally moderate quality with the number of participants varying between 16 and 1082, with 10 having less than 100 participants. The total numbers of trial participants who underwent laparoscopic or open surgery were 2429 and 2139, respectively. A systematic review of four papers suggested that laparoscopic surgery is more costly than open surgery. However, the data they provided on effectiveness was poorer than the evidence from the review of effectiveness. The estimates from the systematic review of clinical effectiveness were incorporated into a Markov model used to estimate cost-effectiveness for a time horizon of up to 25 years. In terms of incremental cost per life-year, laparoscopic surgery was found to be more costly and no more effective than open surgery. With respect to incremental cost per QALY, few data were available to differentiate between laparoscopic and open surgery. The results of the base-case analysis indicate that there is an approximately 40% chance that laparoscopic surgery is the more cost-effective intervention at a threshold willingness to pay for a QALY of pound 30,000. A second analysis assuming equal mortality and disease-free survival found that there was an approximately 50% likelihood at a similar threshold value. Broadly similar results were found in the sensitivity analyses. A threshold analysis was performed to investigate the magnitude of QALY gain associated with quicker recovery following laparoscopic surgery required to provide an incremental cost per QALY of pound 30,000. The implied number of additional QALYs required would be 0.009-0.010 compared with open surgery.

CONCLUSIONS

Laparoscopic resection is associated with a quicker recovery (shorter time to return to usual activities and length of hospitalisation) and no evidence of a difference in mortality or disease-free survival up to 3 years following surgery. However, operation times are longer and a significant number of procedures initiated laparoscopically may need to be converted to open surgery. The rate of conversion may be dependent on experience in terms of both patient selection and performing the technique. Laparoscopic resection appears more costly to the health service than open resection, with an estimated extra total cost of between pound 250 and pound 300 per patient. In terms of relative cost-effectiveness, laparoscopic resection is associated with a modest additional cost, short-term benefits associated with more rapid recovery and similar long-term outcomes in terms of survival and cure rates up to 3 years. Assuming equivalence of long-term outcomes, a judgement is required as to whether the benefits associated with earlier recovery are worth this extra cost. The long-term follow-up of the RCT cohorts would be very useful further research and ideally these data should be incorporated into a wider IPD meta-analysis. Data on the long-term complications of surgery such as incisional hernias and differences in outcomes such as persisting pain would also be valuable. Once available, further data on both costs and utilities should be included in an updated model. At this point, further consideration should then be given as to whether additional data should be collected within ongoing trials. Few data were available to assess the relative merits of HALS. Ideally, there should be more data from methodologically sound RCTs. Further research is needed on whether the balance of advantages and disadvantages of laparoscopic surgery varies within subgroups based on the different stages and locations of disease. Research relating to the effect of experience on performance is also required.

Prevalence of anaemia in patients with diabetes mellitus

BACKGROUND

Anaemia is an increasingly recognised entity in patients with diabetes mellitus.

AIMS

We aimed to determine the prevalence of anaemia in our population of patients with diabetes, and to examine the factors associated with anaemia.

METHODS

The haemoglobin (Hb) levels in a consecutive series of patients attending for annual review of their diabetes over a three-month period were measured. Patients were classified as anaemic as per the WHO criteria.

RESULTS

During the period of study, 270 patients attended for review. Eleven per cent of males and 16% of females were anaemic. Seventy four per cent of anaemic patients had a serum creatinine <110micromol/l and 72% of anaemic patients had a calculated creatinine clearance of >60ml/min.

CONCLUSIONS

Anaemia was relatively common in patients attending for routine outpatient diabetes clinic review. The high prevalence of anaemia supports the routine screening for anaemia in the diabetes out-patient clinic, including in those without overt nephropathy.

Autoantibodies in lung cancer: possibilities for early detection and subsequent cure

BACKGROUND

People with lung cancer usually present at a late stage in the course of their disease when their chances of long-term survival are low. At present there is little to offer for early diagnosis, even in those at high risk of developing the disease. Autoantibodies have been shown to be present in the circulation of people with various forms of solid tumour before cancer-associated antigens can be detected, and these molecules can be measured up to 5 years before symptomatic disease.

OBJECTIVE

To assess the potential of a panel of tumour-associated autoantibody profiles as an aid to other lung cancer screening modalities.

METHODS

Plasma from normal controls (n = 50), patients with non-small cell lung cancer (n = 82) and patients with small cell lung cancer (n = 22) were investigated for the presence of autoantibodies to p53, c-myc, HER2, NY-ESO-1, CAGE, MUC1 and GBU4-5 by enzyme-linked immunosorbent assay.

RESULTS

Raised levels of autoantibodies were seen to at least 1/7 antigens in 76% of all the patients with lung cancer plasma tested, and 89% of node-negative patients, with a specificity of 92%. There was no significant difference between the detection rates in the lung cancer subgroups, although more patients with squamous cell carcinomas (92%) could be identified.

CONCLUSION

Measurement of an autoantibody response to one or more tumour-associated antigens in an optimised panel assay may provide a sensitive and specific blood test to aid the early detection of lung cancer.

A common variant of the interleukin 6 receptor (IL-6r) gene increases IL-6r and IL-6 levels, without other inflammatory effects

Interleukin-6 (IL-6) is a key inflammatory cytokine, signalling to most tissues by binding to a soluble IL-6 receptor (sIL-6r), making a complex with gp130. We used 1273 subjects (mean age 68 years) from the InCHIANTI Italian cohort to study common variation in the IL-6r locus and associations with interleukin 6 receptor (IL-6r), IL-6, gp130 and a battery of inflammatory markers. The rs4537545 single nucleotide polymorphism (SNP) tags the functional non-synonymous Asp358Ala variant (rs8192284) in IL-6r (r(2)=0.89, n=343). Individuals homozygous for the rs4537545 SNP minor allele (frequency 40%) had a doubling of IL-6r levels (132.48 pg/ml, 95% CI 125.13-140.27) compared to the common allele homozygous group (68.31 pg/ml, 95% CI 65.35-71.41): in per allele regression models, the rs4537545 SNP accounted for 20% of the variance in sIL-6r, with P=5.1 x 10(-62). The minor allele of rs4537545 was also associated with higher circulating IL-6 levels (P=1.9 x 10(-4)). There was no association of this variant with serum levels of gp130 or with any of the studied pro- and anti-inflammatory markers. A common variant of the IL-6r gene results in major changes in IL-6r and IL-6 serum levels, but with no apparent effect on gp130 levels or on inflammatory status in the general population.

Autonomic dysfunction in dementia

BACKGROUND

There are no studies of autonomic function comparing Alzheimer's disease (AD), vascular dementia (VAD), dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD).

AIMS

To assess cardiovascular autonomic function in 39 patients with AD, 30 with VAD, 30 with DLB, 40 with PDD and 38 elderly controls by Ewing's battery of autonomic function tests and power spectral analysis of heart rate variability. To determine the prevalence of orthostatic hypotension and autonomic neuropathies by Ewing's classification.

RESULTS

There were significant differences in severity of cardiovascular autonomic dysfunction between the four types of dementia. PDD and DLB had considerable dysfunction. VAD showed limited evidence of autonomic dysfunction and in AD, apart from orthostatic hypotension, autonomic functions were relatively unimpaired. PDD showed consistent impairment of both parasympathetic and sympathetic function tests in comparison with controls (all p<0.001) and AD (all p<0.03). DLB showed impairment of parasympathetic function (all p<0.05) and one of the sympathetic tests in comparison with controls (orthostasis; p = 0.02). PDD had significantly more impairment than DLB in some autonomic parameters (Valsalva ratio: p = 0.024; response to isometric exercise: p = 0.002). Patients with VAD showed impairment in two parasympathetic tests (orthostasis: p = 0.02; Valsalva ratio: p = 0.08) and one sympathetic test (orthostasis: p = 0.04). These results were in contrast with AD patients who only showed impairment in one sympathetic response (orthostasis: p = 0.004). The prevalence of orthostatic hypotension and autonomic neuropathies was higher in all dementias than in controls (all p<0.05).

CONCLUSION

Autonomic dysfunction occurs in all common dementias but is especially prominent in PDD with important treatment implications.

Common genetic variation in the gene encoding interleukin-1-receptor antagonist (IL-1RA) is associated with altered circulating IL-1RA levels

Interleukin-1-receptor antagonist (IL-1RA) modulates the biological activity of the proinflammatory cytokine interleukin-1 (IL-1) and could play an important role in the pathophysiology of inflammatory and metabolic traits. We genotyped seven single nucleotide polymorphisms (SNPs) that capture a large proportion of common genetic variation in the IL-1RN gene in 1256 participants from the Invecchiare in Chianti study. We identified five SNPs associated with circulating IL-1RA levels with varying degrees of significance (P-value range=0.016-4.9 x 10(-5)). We showed that this association is likely to be driven by one haplotype, most strongly tagged by rs4251961. This variant is only in weak linkage disequilibrium (r(2)=0.25) with a previously reported variable number of tandem repeats polymorphism (VNTR) in intron-2 although a second variant, rs579543, that tags the VNTR (r(2)=0.91), may also be independently associated with IL-1RA levels (P=0.03). We found suggestive evidence that the C allele at rs4251961 that lowers IL-1RA levels is associated with an increased IL-1beta (P=0.03) level and may also be associated with interferon -gamma (P=0.03), alpha-2 macroglobulin (P=0.008) and adiponectin (P=0.007) serum levels. In conclusion, common variation across the IL-1RN gene is strongly associated with IL-1RA levels.

Autoantibodies in breast cancer: their use as an aid to early diagnosis

BACKGROUND

There is increasing evidence that the immune system produces a humoral response to cancer-derived antigens. This study assessed the diagnostic potential of autoantibodies to multiple known tumour-associated proteins.

PATIENTS AND METHODS

Sera from normal controls (n = 94), primary breast cancer patients (n = 97) and patients with ductal carcinoma in situ (DCIS) (n = 40) were investigated for the presence of autoantibodies to p53, c-myc, HER2, NY-ESO-1, BRCA1, BRCA2 and MUC1 antigens by enzyme-linked immunosorbent assay.

RESULTS

Reproducibly elevated levels of autoantibodies were seen in at least one of the six antigens in 64% of primary breast cancer patient sera and 45% of patients with DCIS at a specificity of 85%. No significant differences were seen when patients were subdivided by age, tumour size, histological grade, lymph node status or detection methodology.

CONCLUSIONS

Autoantibodies against one or more of these tumour-associated antigens appears to indicate the presence of early-stage breast cancers. Autoantibody assays against a panel of antigens could be used as an aid to mammography in the detection and diagnosis of early primary breast cancer, especially in younger women at increased risk of breast cancer where mammography is known to have reduced sensitivity and specificity.

'Ovar-Mhc' - ovine major histocompatibility complex: structure and gene polymorphisms

The major histocompatibility complex (MHC) in sheep, Ovar-Mhc, is poorly characterised, when compared to other domestic animals. However, its basic structure is similar to that of other mammals, comprising class I, II and III regions. Currently, there is evidence for the existence of four class I loci. The class II region is better characterised, with evidence of one DRA, four DRB (one coding and three non-coding), one DQA1, two DQA2, and one each of the DQB1, DQB2, DNA, DOB, DYA, DYB, DMA, and DMB genes in the region. The class III region is the least characterised, with the known presence of complement cascade (C4, C2 and Bf), TNFalpha and CYP21 genes. Products of the class I and II genes, MHC molecules, play a pivotal role in antigen presentation required for eliciting immune responses against invading pathogens. Several studies have focused on polymorphisms of Ovar-Mhc genes and their association with disease resistance. However, more research emphasis is needed on characterising the remaining Ovar-Mhc genes and developing simplified and cost-effective methods to score gene polymorphisms. Haplotype screening, employing multiple markers rather than single genes, would be more meaningful in MHC-disease association studies, as it is well known that most of the MHC loci are tightly linked, exhibiting very little recombination. This review summarises the current knowledge of the structure of Ovar-Mhc and polymorphisms of genes located in the complex.

Carriage, quantification, and predominance of methanogens and sulfate-reducing bacteria in faecal samples

AIMS

To determine carriage rates and densities of methanogens and sulfate-reducing bacteria in adults and children using molecular methods, and to also determine if a reciprocal relationship exists between these organisms.

METHODS AND RESULTS

Real-time PCR was used to detect and quantify methanogens and sulfate-reducing bacteria. Real-time PCR was more sensitive than breath methane measurements. Real-time PCR assays were applied to faecal DNA samples collected from 40 children and 12 adults. Methanogens were present in 25% of the children and 42% of the adults studied, and sulfate-reducing bacteria were detected in 15% of the children and 58% of the adults. High levels of sulfate-reducing bacteria were found in two methanogenic adults.

CONCLUSIONS

Carriage rates and densities of methanogens and sulfate-reducing bacteria are greater in adults than in children. Competition does not necessarily lead to the predominance of one group in the faecal microflora.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study describes sensitive, molecular assays that could be used to monitor these organisms in gastrointestinal disease. Therapeutic exclusion of one group from the bowel would not necessarily lead to the expansion of the other, as there does not appear to be a reciprocal relationship between these groups.

Malignancy-induced autoimmunity to MUC1: initial antibody characterization

Numerous reports document the existence of autoantibodies to MUC1 in the circulation of individuals with breast and other solid malignancies, with the majority of researchers utilizing MUC1 peptides in their detection. This report documents the purification, using peptide and whole molecule, and characterization of such autoantibodies from an individual with an unusual, highly MUC1-positive, myosarcoma. Purification of autoantibodies from serum was performed using affinity chromatography against either MUC1 peptide or whole molecule MUC1 [derived both from the patient (Pt-MUC1) and from a pool of sera from patients with advanced breast cancer (ABC-MUC1)]. Enzyme-linked immunosorbent assays (ELISAs) were used to compare specificity of purified autoantibodies. Peptide epitopes were determined by Ptifcan system against 7-mer peptides covering the 20 amino acid repeat of the MUC1 extracellular domain. Substantially higher amounts of autoantibodies were isolated when purifying against Pt-MUC1 rather than either ABC-MUC1 or peptide. Whole molecule purified autoantibodies demonstrated an increased specificity for tumour-derived MUC1. Pt-MUC1 autoantibodies were of both the immunoglobulin (Ig)G and IgM class, whilst autoantibodies purified against ABC-MUC1 and MUC1 peptide were IgG only. A greater range of peptide epitopes was defined by those autoantibodies purified against whole molecule. This report presents data indicating the presence of autoantibodies to MUC1 in an individual diagnosed with a MUC1 over-expressing myosarcoma. Confirmation of these autoantibodies as being specific for tumour-associated MUC1 is given. Further, it suggests that, although autoantibodies are present that recognize core protein determinants, the initial, and dominant, immunizing epitope is not purely pretentious in nature.

‘Ovar-Mhc‘— Ovine major histocompatibility complex: Role in genetic resistance to diseases

Research on the structure of the ovine major histocompatibility complex (MHC), Ovar-Mhc, and its association with resistance to various diseases in sheep has received increasing attention during recent years. The term 'resistance' is used to denote the capacity of an animal to defend itself against disease or to withstand the effects of a harmful environmental agent. The Ovar-Mhc is poorly characterised when compared to MHCs of other domestic animals. However, its basic structure is similar to that of other animals, comprising Class I, II and III regions. Products of the Class I and II genes, the histocompatibility molecules, are of paramount importance as these present antigens to T-lymphocytes, thereby eliciting immune responses. Several studies have been conducted in sheep on the involvement of MHC genes/antigens in genetic resistance to diseases, the majority being concerned with gastrointestinal nematodes. Studies on resistance to footrot, Johne's disease and bovine leukaemia virus (BLV)-induced leukaemogenesis have also been reported. Genes of all three regions were implicated in the disease association studies. In addition to disease resistance, Ovar-Mhc genes have been found to be associated with traits such as marbling and birthweight. The use of genetic markers from within the Ovar-Mhc may be useful, via marker-assisted selection, for increasing resistance to various diseases provided they do not impact negatively on other economically-important traits. This review summarises current knowledge of the role of Ovar-Mhc in genetic resistance to diseases in sheep.

An investigation of FRAXA intermediate allele phenotype in a longitudinal sample

The FRAXA trinucleotide repeat at Xq27.3 gives rise to fragile X syndrome when fully expanded, and both premature ovarian failure (POF) and fragile X tremor and ataxia syndrome (FXTAS) when in the premutation range. Reports of phenotypic effects extending into the intermediate repeat range are inconsistent but some studies suggest that these smaller expansions predispose to special educational needs (SEN). This study utilises the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort to investigate cognitive and behavioural variables that might be associated with FRAXA intermediate alleles. The current study failed to find any strong evidence of association of FRAXA intermediate alleles with SEN, behavioural problems or cognitive difficulties. However, our findings illustrate some of the difficulties encountered in identifying individuals with SEN. The power to identify specific components of cognitive and behavioural difficulties was reduced due to elective drop-out, which is characteristic of longitudinal studies. Our findings demonstrate the non-random loss of participants from this cohort and highlight problems that may arise when such data are used in genetic association studies.

Microbial growth in vials of Botulinum toxin following use in clinic

PURPOSE

Botulinum toxin has various applications in ophthalmology and is used in the outpatient department, where it is often exposed to room temperatures for 3-4 h. The manufacturer's recommendations are that the reconstituted toxin be stored in a refrigerator when not in use and discarded 4 h after reconstitution. The aim of our study was to examine such used bottles of Botulinum toxin for microbial growth after 4 h at room temperature.

METHODS AND RESULTS

Eleven consecutive bottles of Botulinum toxin used with aseptic precautions in the Ophthalmology outpatient clinics were exposed to room temperatures for 4 h. These were subsequently analysed for microbial growth. No growth was directly obtained from any of the Botulinum toxin bottles during our study.

CONCLUSIONS

This pilot study suggests that if aseptic precautions are followed during the use of Botulinum toxin, the contents of the bottle remain sterile despite being exposed to room temperatures for up to 4 h. This has implications on the use of the reconstituted toxin after the recommended 4 h.