Biomarker-guided trials: Challenges in practice.

Biomarker-guided trials have drawn considerable attention as they promise to lead to improvements in the benefit-risk ratio of treatments and enhanced opportunities for drug development. A variety of such designs have been proposed in the literature, many of which have been adopted in practice. Implementing such trial designs in practice can be challenging, and identifying those challenges was the main objective of a workshop organised by the MRC Hubs for Trials Methodology Research Network's Stratified Medicine Working Group in March 2017. Participants reflected on completed and ongoing biomarker-guided trials to identify the practical challenges encountered. Here, the key challenges identified during the workshop including those related to funding, ethical and regulatory issues, recruitment, monitoring of samples and laboratories, biomarker assessment, and data sharing and resources, are discussed. Despite the complexities often associated with biomarker-guided trials, the workshop concluded that they can play an important role in advancing the field of personalised medicine. Therefore, it is important that the practical challenges surrounding their implementation are acknowledged and addressed.

NAT2 variants and toxicity related to anti-tuberculosis agents: a systematic review and meta-analysis.

BACKGROUND: Tuberculosis (TB) patients receiving anti-tuberculosis treatment may experience serious adverse drug reactions (ADRs) such as hepatotoxicity. Variants of the N-acetyltransferase 2 (NAT2) gene may increase the risk of experiencing such toxicity events. OBJECTIVE: To provide a comprehensive evaluation of the evidence base for associations between NAT2 variants and anti-tuberculosis drug-related toxicity. METHOD: This was a systematic review and meta-analysis. We searched for studies in Medline, PubMed, EMBASE, BIOSIS and Web of Science. We included data from 41 articles (39 distinct cohorts of patients). We pooled effect estimates for each genotype on each outcome using meta-analyses stratified by country. RESULTS: We assessed the quality of the included studies, which was variable, with many areas of concern. Slow/intermediate NAT2 acetylators were statistically significantly more likely to experience hepatotoxicity than rapid acetylators (OR 1.59, 95%CI 1.26-2.01). Heterogeneity was not detected in the overall pooled analysis (I² = 0%). NAT2 acetylator status was significantly associated with the likelihood of experiencing anti-tuberculosis drug-related hepatotoxicity. CONCLUSION: We encountered several challenges in performing robust syntheses of data from pharmacogenetic studies, and we outline recommendations for the future reporting of pharmacogenetic studies to enable high-quality systematic reviews and meta-analyses to be performed.

Serum and blister-fluid elevation and decreased epidermal content of high-mobility group box 1 protein in drug-induced Stevens-Johnson syndrome/toxic epidermal necrolysis.

BACKGROUND: High-mobility group box 1 (HMGB1) is a damage-associated molecular-pattern protein. Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) are serious, immune-mediated skin-blistering conditions. OBJECTIVES: To determine serum and/or blister-fluid total HMGB1 levels in SJS/TEN cohorts, and HMGB1 expression in formalin-fixed, paraffin-embedded (FFPE) SJS/TEN skin vs. healthy and maculopapular exanthema (MPE) skin. Methods Serum HMGB1 was quantified in Malawian nevirapine-induced hypersensitivity, Taiwanese SJS/TEN and Spanish SJS/TEN cohorts. FFPE skin (healthy skin, MPE, SJS/TEN) was stained and assessed for HMGB1 expression. RESULTS: Serum total HMGB1 was not significantly elevated in patients with nevirapine-induced SJS/TEN (3·98 ± 2·17 ng mL-1 ), MPE (3·92 ± 2·75 ng mL-1 ) or drug reaction with eosinophilia and systemic symptoms (4·73 ± 3·00 ng mL-1 ) vs. tolerant controls (2·97 ± 3·00 ng mL-1 ). HMGB1 was significantly elevated in Taiwanese patients with SJS/TEN, highest during the acute phase (32·6 ± 26·6 ng mL-1 ) vs. the maximal (19·7 ± 23·2 ng mL-1 ; P = 0·007) and recovery (24·6 ± 25·3 ng mL-1 ; P = 0·027) phases. In blister fluid from Spanish patients with SJS/TEN, HMGB1 (486·8 ± 687·9 ng mL-1 ) was significantly higher than in serum (8·8 ± 7·6 ng mL-1 ; P <0·001). Preblistered SJS/TEN skin showed decreased epidermal nuclear HMGB1 expression in upper epidermis vs. healthy or MPE skin but retained basal/suprabasal expression. CONCLUSIONS: Epidermal HMGB1 expression was decreased in SJS/TEN skin. Retained basal/suprabasal epidermal HMGB1 expression may exacerbate localized injury in SJS/TEN.

Growing international evidence for urinary biomarker panels identifying lupus nephritis in children - verification within the South African Paediatric Lupus Cohort.

BACKGROUND: A urinary biomarker panel including alpha-1-acid-glycoprotein (AGP), lipocalin-like-prostaglandin-D-synthase (LPGDS), transferrin and ceruloplasmin demonstrates an 'excellent' ability for identifying active lupus nephritis in UK/US children. This study aimed to assess whether this panel identifies active lupus nephritis within the South African Paediatric Lupus Cohort. METHODS: Juvenile-onset-systemic lupus erythematosus (JSLE) patients aged < 19 years at diagnosis and healthy controls were recruited. Patients were categorized as having active lupus nephritis (renal BILAG score; A/B and previous histological confirmation) or inactive lupus nephritis (renal BILAG score: D/E). Urinary biomarkers were quantified by ELISA. Mann-Whitney U-test compared biomarker levels between groups. Binary logistic regression and receiver operating curve analysis assessed biomarker combinations. RESULTS: Twenty-three juvenile-onset-systemic lupus erythematosus patients were recruited with a median age of 13.5 years (interquartile range (IQR) 12.7-14.9) and disease duration of 2.6 years (IQR 1.8-4.0). Eighteen healthy controls had a median age of 11.0 years (IQR 10.0-12.0). AGP, LPGDS, transferrin, ceruloplasmin and VCAM-1 were significantly higher in active than in inactive lupus nephritis patients (corrected p-values, all pc < 0.05), with no difference between inactive lupus nephritis patients and healthy controls (all pc = 1.0). The optimal biomarker combination included AGP, ceruloplasmin, LPGDS and transferrin (area under the curve = 1.0). CONCLUSIONS: A urinary biomarker panel comprising AGP, ceruloplasmin, LPGDS and transferrin previously validated within UK/US cohorts also performed excellently within a racially distinct South African cohort which displayed more severe lupus nephritis.

Clinical predictors of active LN development in children - evidence from the UK JSLE Cohort Study.

BACKGROUND: Juvenile-onset systemic lupus erythematosus (JSLE) patients may develop lupus nephritis (LN) during their initial presentation, or later in their disease. This study aimed to assess whether clinical/demographic factors characterize patients with LN within the United Kingdom JSLE Cohort Study, and whether such factors predict subsequent LN development. METHODS: Univariate logistic regression modelling compared clinical/demographic factors in patients with and without LN at baseline. For those who subsequently developed LN, Cox proportional-hazard modelling was used to test the association between such factors and time to LN development. Covariates with p < 0.2 univariately were included within a multiple-regression model. RESULTS: A total of 121/331 (37%) patients presented with active LN at baseline, with first American College of Rheumatology (ACR) score ( p < 2.0 × 10-16), severe hypertension ( p = 0.0006), proteinuria ( p < 2.0 × 10-16), creatinine ( p = 1.0 × 10-16), erythrocyte sedimentation rate ( p = 1.0 × 10-16), neutrophils ( p < 2.0 × 10-16), complement 3 (C3) ( p = 4.0 × 10-16) and ethnicity ( p = 3.0 × 10-13) differing between those with and without LN. Of the 210 individuals without active LN at baseline, 13 patients had a single visit and were excluded from further analysis. Thirty-four of 197 (17%) developed LN after a median of 2.04 years (interquartile range, 0.8-3.7), with higher ACR scores ( p = 0.014 , hazard ratio (HR) = 1.45, 95% confidence interval (CI) = 1.08-1.95) and lower C3 levels ( p = 0.0082 , HR = 0.27, 95% CI = 0.10-0.68) demonstrated as predictors of subsequent LN. CONCLUSIONS: Clinical and demographic factors can help to characterize patients at increased risk of LN.

The molecular genetics of chemotherapy-induced peripheral neuropathy: A systematic review and meta-analysis.

Chemotherapy-induced peripheral neuropathy (CIPN) can adversely affect completion of systemic anti-cancer treatment and cause long-term morbidity. Increasingly pharmacogenetic studies have been performed to explore susceptibility to this important adverse effect. A systematic review was conducted to identify pharmacogenetic studies, assess their quality and findings and undertake meta-analysis where possible. 93 studies were included. Notable methodological issues included lack of standardisation and detail in phenotype definition and acknowledgement of potential confounding factors. Insufficient data was presented in many studies meaning only a minority could be included in meta-analysis showing mainly non-significant effects. Nonetheless, SNPs in CYP2C8, CYP3A4, ARHGEF10, EPHA and TUBB2A genes (taxanes), FARS2, ACYP2 and TAC1 (oxaliplatin), and CEP75 and CYP3A5 (vincristine) are of potential interest. These require exploration in large cohort studies with robust methodology and well-defined phenotypes. Seeking standardisation of phenotype, collaboration and subsequently, individual-patient-data meta-analysis may facilitate identifying contributory SNPs which could be combined in a polygenic risk score to predict those most at risk of CIPN.

Do classic blood biomarkers of JSLE identify active lupus nephritis? Evidence from the UK JSLE Cohort Study.

Background Lupus nephritis (LN) affects up to 80% of juvenile-onset systemic lupus erythematosus (JSLE) patients. The value of commonly available biomarkers, such as anti-dsDNA antibodies, complement (C3/C4), ESR and full blood count parameters in the identification of active LN remains uncertain. Methods Participants from the UK JSLE Cohort Study, aged <16 years at diagnosis, were categorized as having active or inactive LN according to the renal domain of the British Isles Lupus Assessment Group score. Classic biomarkers: anti-dsDNA, C3, C4, ESR, CRP, haemoglobin, total white cells, neutrophils, lymphocytes, platelets and immunoglobulins were assessed for their ability to identify active LN using binary logistic regression modeling, with stepAIC function applied to select a final model. Receiver-operating curve analysis was used to assess diagnostic accuracy. Results A total of 370 patients were recruited; 191 (52%) had active LN and 179 (48%) had inactive LN. Binary logistic regression modeling demonstrated a combination of ESR, C3, white cell count, neutrophils, lymphocytes and IgG to be best for the identification of active LN (area under the curve 0.724). Conclusions At best, combining common classic blood biomarkers of lupus activity using multivariate analysis provides a 'fair' ability to identify active LN. Urine biomarkers were not included in these analyses. These results add to the concern that classic blood biomarkers are limited in monitoring discrete JSLE manifestations such as LN.

SLCO1B1 genetic variant associated with statin-induced myopathy: a proof-of-concept study using the clinical practice research datalink.

This study aimed to determine whether patients with statin-induced myopathy could be identified using the United Kingdom Clinical Practice Research Datalink, whether DNA could be obtained, and whether previously reported associations of statin myopathy with the SLCO1B1 c.521T>C and COQ2 rs4693075 polymorphisms could be replicated. Seventy-seven statin-induced myopathy patients (serum creatine phosphokinase (CPK) > 4× upper limit of normal (ULN)) and 372 statin-tolerant controls were identified and recruited. Multiple logistic regression analysis showed the SLCO1B1 c.521T>C single-nucleotide polymorphism to be a significant risk factor (P = 0.009), with an odds ratio (OR) per variant allele of 2.06 (1.32-3.15) for all myopathy and 4.09 (2.06-8.16) for severe myopathy (CPK > 10× ULN, and/or rhabdomyolysis; n = 23). COQ2 rs4693075 was not associated with myopathy. Meta-analysis showed an association between c.521C>T and simvastatin-induced myopathy, although power for other statins was limited. Our data replicate the association of SLCO1B1 variants with statin-induced myopathy. Furthermore, we demonstrate how electronic medical records provide a time- and cost-efficient means of recruiting patients with severe adverse drug reactions for pharmacogenetic studies.

HLA genotype and carbamazepine-induced cutaneous adverse drug reactions: a systematic review.

Carbamazepine (CBZ) therapy is associated with cutaneous adverse reactions in up to 10% of patients. Predisposition to these hypersensitivity reactions has been linked to the human leukocyte antigen (HLA) genotype. This systematic review determines the strength of these associations and accuracy of proposed genetic screening. We determined that carriage of HLA-B*1502 in Asian patients was associated with a pooled odds ratio (OR) of 113.4 (95% confidence interval (CI) = 51.2-251.0, P < 1 × 10(-5)) for CBZ-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). A total of 461 patients would need to be screened for HLA-B*1502 to prevent one episode of SJS/TEN. HLA-A*3101 is significantly associated with all phenotypes of CBZ hypersensitivity in multiple ethnicities with a pooled OR of 9.5 (95% CI = 6.4-13.9, P < 1 × 10(-5)). Between 47 and 67 patients would need to be tested for HLA-A*3101 to prevent one episode of hypersensitivity. Our findings suggest that HLA testing before carbamazepine therapy would be effective at identifying individuals at risk of hypersensitivity and applicable to multiple populations providing hope for prevention in the future.

Proteomic and peptidomic study of proteolysis in quarter milk after infusion with lipoteichoic acid from Staphylococcus aureus.

Mastitic milk is associated with increased bovine protease activity, such as that from plasmin and somatic cell enzymes, which cause proteolysis of the caseins and may reduce cheese yield and quality. The aim of this work was to characterize the peptide profile resulting from proteolysis in a model mastitis system and to identify the proteases responsible. One quarter of each of 2 cows (A and B) was infused with lipoteichoic acid from Staphylococcus aureus. The somatic cell counts of the infused quarters reached a peak 6h after infusion, whereas plasmin activity of those quarters also increased, reaching a peak after 48 and 12h for cow A and B, respectively. Urea-polyacrylamide gel electrophoretograms of milk samples of cow A and B obtained at different time points after infusion and incubated for up to 7 d showed almost full hydrolysis of ß- and α(S1)-casein during incubation of milk samples at peak somatic cell counts, with that of ß-casein being faster than that of α(S1)-casein. Two-dimensional gel electrophoretograms of milk 6h after infusion with the toxin confirmed hydrolysis of ß- and α(S1)-casein and the appearance of lower-molecular-weight products. Peptides were subsequently separated by reversed-phase HPLC and handmade nanoscale C(18) columns, and identified by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry. Twenty different peptides were identified and shown to originate from α(s1)- and ß-casein. Plasmin, cathepsin B and D, elastase, and amino- and carboxypeptidases were suggested as possible responsible proteases based on the peptide cleavage sites. The presumptive activity of amino- and carboxypeptidases is surprising and may indicate the activity of cathepsin H, which has not been reported in milk previously.

Integration of genetic, clinical, and INR data to refine warfarin dosing.

Well-characterized genes that affect warfarin metabolism (cytochrome P450 (CYP) 2C9) and sensitivity (vitamin K epoxide reductase complex 1 (VKORC1)) explain one-third of the variability in therapeutic dose before the international normalized ratio (INR) is measured. To determine genotypic relevance after INR becomes available, we derived clinical and pharmacogenetic refinement algorithms on the basis of INR values (on day 4 or 5 of therapy), clinical factors, and genotype. After adjusting for INR, CYP2C9 and VKORC1 genotypes remained significant predictors (P < 0.001) of warfarin dose. The clinical algorithm had an R(2) of 48% (median absolute error (MAE): 7.0 mg/week) and the pharmacogenetic algorithm had an R(2) of 63% (MAE: 5.5 mg/week) in the derivation set (N = 969). In independent validation sets, the R(2) was 26-43% with the clinical algorithm and 42-58% when genotype was added (P = 0.002). After several days of therapy, a pharmacogenetic algorithm estimates the therapeutic warfarin dose more accurately than one using clinical factors and INR response alone.

Efficiency of two enucleation methods connected to handmade cloning to produce transgenic porcine embryos.

The purpose of our work was to establish an efficient-oriented enucleation method to produce transgenic embryos with handmade cloning (HMC). After 41-42 h oocytes maturation, the oocytes were further cultured with or without 0.4 microg/ml demecolcine for 45 min [chemically assisted handmade enucleation (CAHE) group vs polar body (PB) oriented handmade enucleation (OHE) group respectively]. After removal of the cumulus cells and partial digestion of the zona pellucida, oocytes with visible extrusion cones and/or polar bodies attached to the surface were subjected to oriented bisection. Putative cytoplasts without extrusion cones or PB were selected as recipients. Two cytoplasts were electrofused with one transgenic fibroblasts expressing green fluorescent protein (GFP), while non-transgenic fibroblasts were used as controls. Reconstructed embryos were cultured in Well of Wells (WOWs) with porcine zygote medium 3 (PZM-3) after activation. Cleavage and blastocyst rates were registered on day 2 and day 7 of in vitro culture respectively. Meanwhile, the total blastocyst cell number was counted on day 7. We found that the difference was only observed between blastocyst rates (38.6 +/- 2% vs 48.1 +/- 3%) of cloned embryos with GFP transgenic fibroblast cells after CAHE vs OHE. With adjusted time-lapse for zonae-free cloned embryos cultured in WOWs with PZM-3, it was obvious that in vitro developmental competence after CAHE was compromised when compared with the OHE method. OHE enucleation method seems to be a potential superior alternative method used for somatic cell nuclear transfer (SCNT) with transgenic fibroblast cells.

Cervical stitch (cerclage) for preventing pregnancy loss: individual patient data meta-analysis.

BACKGROUND: Several observational studies have claimed high success rates for cerclage in women with cervical insufficiency. A recent Cochrane review found no conclusive evidence of benefit, although significant heterogeneity was present for some of the important clinical outcomes. OBJECTIVES: We undertook an individual patient data (IPD) meta-analysis to examine effect of cerclage on neonatal and maternal outcomes. In an attempt to explain the heterogeneity, we investigated whether obstetric factors including multiple gestation are associated with effectiveness. SEARCH STRATEGY: Search methods described in the original Cochrane review were adopted and updated to December 2005. SELECTION CRITERIA: This IPD systematic review and meta-analysis was of randomised trials comparing cervical cerclage during pregnancy with expectant management or no cerclage in women with confirmed or suspected as having cervical insufficiency. ANALYSIS: Multilevel logistic regression models stratified by trial with random treatment effects were fitted to investigate the impact of obstetric factors and multiple gestation on treatment effect. Primary outcome measures were pregnancy loss or death before discharge from hospital and absence of neonatal morbidity. MAIN RESULTS: The meta-analysis included seven trials and 2091 randomised women. In singleton pregnancies, the reduction in pregnancy loss or death before discharge from hospital following cerclage failed to reach statistical significance (OR 0.81; 95% CI 0.60-1.10). Cerclage was found to have a detrimental effect on the outcome of pregnancy loss or death before discharge from hospital in multiple gestations (OR 5.88; 95% CI 1.14-30.19), although only a small number of multiple pregnancies were included in the analysis. Neither indication for cerclage nor obstetric history was found to have a statistically significant impact on the effect of cerclage. CONCLUSIONS: Cerclage may reduce the risk of pregnancy loss or neonatal death before discharge from hospital in singleton pregnancies thought to be at risk of preterm birth, but further large trials are needed to elucidate the risk-benefit ratio precisely. Cerclage in multiple pregnancies should be avoided. The efficacy of cerclage was not influenced by either indication for cerclage or mother's obstetric history.

Piglets born from handmade cloning, an innovative cloning method without micromanipulation.

Porcine handmade cloning (HMC), a simplified alternative of micromanipulation based traditional cloning (TC) has been developed in multiple phases during the past years, but the final evidence of its biological value, births of piglets was missing. Here we report the first births of healthy piglets after transfer of blastocysts produced by HMC. As a cumulative effect of technical optimization, 64.3+/-2.3 (mean+/-S.E.M.) reconstructed embryos from 151.3+/-4.8 oocytes could be obtained after 3-4h manual work, including 1h pause between fusion and activation. About half (50.1+/-2.8%, n=16) of HMC reconstructed embryos developed to blastocysts with an average cell number of 77+/-3 (n=26) after 7 days in vitro culture (IVC). According to our knowledge, this is the highest in vitro developmental rate after porcine somatic cell nuclear transfer (SCNT). A total of 416 blastocysts from HMC, mixed with 150 blastocysts from TC using a cell line from a different breed were transferred surgically to nine synchronized recipients. Out of the four pregnancies (44.4%) two were lost, while two pregnancies went to term and litters of 3 and 10 piglets were delivered by Caesarean section, with live birth/transferred embryo efficiency of 17.2% (10/58) for HMC. Although more in vivo experiments are still needed to further stabilize the system, our data proves that porcine HMC may result in birth of healthy offspring. Future comparative examinations are required to prove the value of the new technique for large-scale application.

Creutzfeldt-Jakob disease segregating in a three generation Danish family.

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

A presenilin-1 Thr116Asn substitution in a family with early-onset Alzheimer's disease.

Mutation in the presenilin-1 (PS-1) gene at chromosome 14q24.3 is the most common cause of autosomal dominant early-onset Alzheimer's disease. Here, we report a novel missense mutation in the presenilin-1 gene found in a three-generation Danish family with autopsy-verified early-onset Alzheimer's disease. Two affected first-degree relatives in two generations were found to be heterozygous for a cytosine to adenine transversion at the second position of codon 116, which changes the amino acid at that position from threonine to asparagine. This conservative amino acid substitution occurs in an evolutionary highly conserved region of the PS-1 protein and is associated with onset of the disease between age 35 and 41 years and 4-8 years' duration of the disease. Analysis of amyloid beta-protein (A beta) deposition in brain specimens from one affected family member showed predominance of A beta 42(43). Onset and progression of the disease were very similar in two sibs homozygous for the epsilon 3 allele and the epsilon 4 allele, respectively, of the polymorphic apolipoprotein E locus. The lack of effect of the high risk epsilon 4/epsilon 4 genotype on the disease in this family corroborates and extends previous observations that the presence of one copy of the epsilon 4 allele does not modulate PS-1 associated Alzheimer's disease.

Alphoid repetitive DNA in human chromosomes.

The thesis describes the first extensive DNA sequence analysis that demonstrated that the tandemly repeated alphoid DNA in the centromere of the human chromosomes consists of distinct subfamilies and in a number equal to or exceeding the number of chromosomes. The expected presence of only one or a few distinct subfamily on individual chromosomes was supported by the characterization of an extremely well-defined subfamily specific for chromosome 7 and represented in the original collection of subfamilies. The pattern of chromosome-specificity breaks down among the acrocentric chromosomes where chromosomes 13 and 21 were found to share one and chromosomes 14 and 22 to share another specific subfamily. By in situ hybridization these subfamilies were shown not to be shared by other chromosomes. The remarkable pairwise pattern of sequence homogenization was present also in the chimpanzee genome raising the question of its biological role. However, the subfamilies on these human and chimpanzee chromosomes are not orthologous but were shown to originate from two evolutionarily different repeat families. It follows that dramatic sequence evolution has occurred in one or both species during or after separation. The sequence evolution might even occur at a higher rate in humans. This possibility was studied in orthologous alphoid sequences on the X chromosome of humans and the great apes. The analysis supports the general view that our closest relative is the chimpanzee and indicates that the rate of recombination is increased in the human repeat DNA. A "molecular clock" running faster in this DNA may have evolutionary implications. Finally, the usefulness of alphoid subfamilies as chromosome-specific markers is illustrated in a cytogenetic dissection of the centromeric region of Robertsonian translocations. The breakpoints were located to satellite III DNA leaving these chromosomes dicentric. The order of the different tandem DNAs on the p-arm of the acrocentric chromosomes could also be established.

[Alzheimer's disease and genes]. / Alzheimers sygdom og generne.

Alzheimer's disease is genetically heterogeneous. The rare familial early-onset form of the disease is caused by dominant mutations in at least four different genes. Three of these genes have now been identified and the gene for presenilin 1 (PS1) on chromosome 14 is mutated in about 75% of the families. By contrast, the common form of Alzheimer's disease has late onset and may occur as sporadic cases in the families. This form is multifactorial and the most important genetic risk factor is the E4 allele of the polymorphic apolipoprotein E gene (APOE) on chromosome 19. The E4 allele is associated with moderately or strongly increased lifetime risk of Alzheimer's disease in persons with respectively one or two copies of the gene variant. Apolipoprotein E genotyping may serve as an adjunct in the diagnostic evaluation of Alzheimer's disease, but predictive genotyping of asymptomatic persons is premature and should not be done.

[Apolipoprotein E genotypes in patients investigated for dementia]. / Apolipoprotein E-genotyper hos patienter udredt for demens.

Certain genotypes of apolipoprotein E (apoE, locus APOE) are associated with an increased risk for development of Alzheimer's disease. We present the distribution of the APOE alleles (E2, E3 and E4) in 50 Danish patients referred to a dementia clinic. The distribution of alleles in patients with dementia was E2: 2, E3: 36 and E4: 38; and in 12 patients without dementia E2: 1, E3: 18, and E4: 5. The frequency of E4 alleles was significantly increased (chi 2 = 42; df = 1; p < 10(-4)) among patients with Alzheimer's disease compared with a Danish control population. The study demonstrates a strong association between Alzheimer's disease and the E4 allele. No difference was found in the frequency of the E4 allele between Alzheimer and non-Alzheimer demented patients.

Grasping the handrails during treadmill walking does not alter sagittal plane kinematics of walking.

OBJECTIVE: To determine whether grasping the handrails during treadmill walking affects sagittal plane kinematic parameters selected to describe walking style. DESIGN: Crossover trial. SETTING: A university motion analysis laboratory. PARTICIPANTS: A convenience sample comprised of 15 apparently healthy college-age volunteers. INTERVENTION: After being acclimatized to treadmill walking, subjects were videotaped while completing two treadmill walking bouts. Each bout was 10 minutes in duration and was conducted at a walking speed of 1.5m/sec. Subjects were instructed to grasp the handrails in one bout (GRASP) but to refrain from using the handrails in the other (FREE). Both bouts were conducted in a single session and were separated by a 10-minute rest period. The order in which subjects completed the bouts was randomized. MAIN OUTCOME MEASURES: Five successive strides occurring during the last 30 seconds of each bout were digitized. The coordinate data were numerically filtered and the following parameters derived: stride length, percentage of stride cycle spent in double-support, and the hip, knee, and ankle angles at heel-strike and toe-off. The results for the five strides in each bout were averaged and the average value was used in the statistical analysis. The FREE and GRASP conditions were compared with t tests for dependent samples (p < or = .05). RESULTS: There were no differences between the FREE and GRASP conditions for any of the parameters assessed. CONCLUSIONS: Subjects may grasp the treadmill handrails without affecting sagittal plane kinematic parameters of walking style.