P3109Coronary vulnerable plaque development is promoted by multidirectional wall shear stress

Aim

Wall shear stress (WSS) has been widely associated with plaque development and destabilization. However, the multidirectionality of WSS, induced by the pulsatile nature of blood flow in combination with the arterial geometry, is rarely taken into account. The purpose of this study was to investigate the influence and predictive value of five (multidirectional) WSS parameters for coronary plaque progression and composition.

Methods

Familial hypercholesterolemic pigs (n=10, castrated male, 3 years old) were put on a high-fat diet and underwent imaging (near infrared spectroscopy-intravascular ultrasound (NIRS-IVUS), optical coherence tomography (OCT) and CT) of the three main coronary arteries at baseline and 10/12 months follow-up. IVUS-based lumen contours were combined with the centerline of artery as extracted from CT to obtain a 3D reconstruction of the coronary artery. Local flow velocity measurements were combined with the 3D-geometry of the coronary arterial lumen to calculate five multidirectional WSS parameters including: time average wall shear stress (TAWSS), oscilatory shear index (OSI), relative residence time (RRT), trans wall shear stress (TransWSS), cross flow index (CFI). For the analysis, arteries were divided into 3mm/45° sectors (n=3627). Per vessel each segment was classified as low, mid or high for each WSS metric based on the average value in the sector. Changes in wall thickness (WT) and plaque composition were assessed with NIRS-IVUS and OCT, and histology and related to the local (multidirectional) WSS.

Results

Half of the pigs developed lumen intruding, complex, lipid-rich plaques. In these pigs, coronary segments exposed to low baseline levels of TAWSS exhibited a significantly larger plaque growth per month compared to regions with either mid or high TAWSS (p<0.05, see figure). Furthermore, plaque growth correlated positively with the multidirectional WSS metrics OSI, RRT and CFI, with high multidirectionality resulting in the largest plaque growth (see figure). The positive predictive values (PPV) of the WSS metrics for plaque presence (WT>0.5mm) at follow up were 50% (low TAWSS), 48% (high OSI), 49% (high RRT), 47% (high CFI) and 43% (high transWSS). The PPVs for the presence of a fibroatheroma observed with histology were 61% (low TAWSS), 58% (high OSI), 61% (high RRT), 59% (high CFI) and 49% (high transWSS).

Plaque growth vs. multidirectional WSS

Conclusions

This study shows that both low and multidirectional WSS promote the development of large and complex coronary atherosclerotic plaques with vulnerable characteristics. The high predictive values for fibrous cap atheroma development demonstrate the potential of multidirectional WSS metrics as a predictive clinical marker for vulnerable disease.

Acknowledgement/Funding

ERC- starter grant (grant agreement 310457)

Card sorting to evaluate the robustness of the information architecture of a protocol website

OBJECTIVES

A website on Methicillin-Resistant Staphylococcus Aureus, MRSA-net, was developed for Health Care Workers (HCWs) and the general public, in German and in Dutch. The website's content was based on existing protocols and its structure was based on a card sort study. A Human Centered Design approach was applied to ensure a match between user and technology. In the current study we assess whether the website's structure still matches user needs, again via a card sort study.

METHODS

An open card sort study was conducted. Randomly drawn samples of 100 on-site search queries as they were entered on the MRSA-net website (during one year of use) were used as card input. In individual sessions, the cards were sorted by each participant (18 German and 10 Dutch HCWs, and 10 German and 10 Dutch members of the general public) into piles that were meaningful to them. Each participant provided a label for every pile of cards they created. Cluster analysis was performed on the resulting sorts, creating an overview of clusters of items placed together in one pile most frequently. In addition, pile labels were qualitatively analyzed to identify the participants' mental models.

RESULTS

Cluster analysis confirmed existing categories and revealed new themes emerging from the search query samples, such as financial issues and consequences for the patient. Even though MRSA-net addresses these topics, they are not prominently covered in the menu structure. The label analysis shows that 7 of a total of 44 MRSA-net categories were not reproduced by the participants. Additional themes such as information on other pathogens and categories such as legal issues emerged.

CONCLUSIONS

This study shows that the card sort performed to create MRSA-net resulted in overall long-lasting structure and categories. New categories were identified, indicating that additional information needs emerged. Therefore, evaluating website structure should be a recurrent activity. Card sorting with ecological data as input for the cards is useful to identify changes in needs and mental models. By combining qualitative and quantitative analysis we gained insight into additional information needed by the target group, including their view on the domain and related themes. The results show differences between the four user groups in their sorts, which can mostly be explained by the groups' background. These findings confirm that HCD is a valuable approach to tailor information to the target group.

Further evidence of genetic heterogeneity in hereditary hydronephrosis

Hereditary hydronephrosis is a rare condition but several families are described in the literature. The inheritance pattern is autosomal dominant (McKusick number 143400) but the exact aetiology of the hydronephrosis is not clear. However, linkage with the HLA region on chromosome six has been shown previously. We report a family not showing linkage to this region, giving further evidence of genetic heterogeneity in this condition.

Reduced expression of HLA-B35 in schizophrenia

The frequencies of HLA class I (HLA-A, B, C) and class II (HLA-DR, DQ) antigens were measured in 107 unrelated schizophrenic subjects and the results compared with 264 controls from south-east Scotland and a second control group of 133 individuals from north-east England. The expression of HLA-B35 was significantly reduced in the schizophrenic population compared to both control populations and these differences remained significant after correction for multiple testing. Linkage of schizophrenia and the major histocompatibility complex region of chromosome 6p was, however, excluded in a group of 17 families multiply affected with schizophrenia. Linkage was also excluded with several red cell antigens, red cell enzymes and plasma proteins. A negative association between the frequency of an HLA antigen and schizophrenia suggests that immune mechanisms may contribute to the aetiology of the disease in some subjects.

HLA frequencies in Basques in Spain and in neighbouring populations

HLA antigen and gene frequencies at the A, B, and C loci are examined in a sample of 181 Basques and 102 non-Basques in Bilbao, Spain. The most common associations of genes at the A and B loci are as in western Europe generally. The results are compared with gene frequencies in other Basque and non-Basque samples in Spain and France. There is clear distinction in gene frequency between Basques and non-Basques, to which the greatest contribution is made by A1 and B35, followed by B7, B8 and B12; and a difference between Basques in France and in Spain, notably in A28, 29, 30 and 31 and B17 and 18.

Contribution of inherited factors to rheumatoid arthritis

A total of 231 sibships of the same sex (186 female, 45 male), in which the proband had classical or definite rheumatoid arthritis (RA) have been selected from rheumatology clinics. Each sibship member was questioned about symptomatic joints, which were then examined. Hospital records, radiographs, and rheumatoid factor measurements allowed each sibling to be classified as having classical, definite, probable, or no RA. Each sibling was typed for HLA-A and B and was classified as sharing two, one, or zero HLA haplotypes with the proband. Concordance rates for classical and definite RA were three times greater in sibships of women than of men (9.3 v 3.0%). Concordance rates in HLA identical sibships were twice those in hemi- and non-identical sibships (15.5, 7.1, and 5.2%, respectively). Probable RA was more common in male and HLA hemi- and non-identical sibships. These results suggest that female sex and the two inherited HLA haplotypes are important for the presence and expression of RA. Although environmental factors may be shared more in twins than siblings, a concordance rate of 20.5% in seropositive HLA identical sibships of the same sex compared with 30% in monozygotic twins suggests that sex and HLA type account for about two thirds of the inherited risk of RA.

Toneline bite mark photography

In bite mark analyses, the initial photograph is critical for the collection and presentation of evidence. A high-contrast film technique previously used primarily in the graphic arts field has been refined and applied to forensic odontology. The process, called toneline, reduces the interpretational bias of the investigator and yields a transparent overlay with a photographic outline of the bite mark which can be directly compared with models of the suspect's teeth.

HLA antigens in three populations of India

In blood samples from a Hindu population of Uttar Pradesh (North India) and from two Muslim groups, one from Andhra Pradesh (South India) and the other from Gujurat (West India), frequencies of 38 HLA-A, -B and -C antigens were investigated. Eight antigens - A23, A25, A29, A32, Bw45, B21, Bw22 and Bw53 - were absent in the Hindu population, four different antigens - A29, Bw52, B14 and Bw42 - were absent in Hyderabad Muslims, two antigens - A31 and Bw45 - were lacking in Surat Muslims. The three populations showed considerable genetic heterogeneity. The genetic difference between the two Muslim groups was small, but the Hindu population showed pronounced differences from each of the Muslim groups.

Association of HLA and other genetic markers in South Indian patients with pulmonary tuberculosis

Histocompatibility antigens (A, B & C loci) and 23 other single gene characters were studied in 204 pulmonary tuberculosis patients belonging to a single endogamous group in South India. None of the previously reported associations with HLA antigens was confirmed, nor any new one found. The blood O and Rh negative associations were also not confirmed, although a new association with the Jk blood group system appears possible. Of particular interest is the association with the phosphoglucomutase (PGM1) system, which parallels that found in a different population located some 1000 km away. Relative risks were calculated to measure the resistance of individuals with the PGM1*2+ allele.

HLA (class 1 antigen) status and cell-mediated immunity in multiple sclerosis

In vitro lymphocyte proliferation in response to allogeneic pooled cells, phytohaemaglutinin (PHA), and pokeweed mitogen (PWM), was measured in relation to HLA A, B and C status in 67 patients with clinically definite multiple sclerosis and in 67 age- and sex-matched controls. Analysis of covariance taking age into account showed significant effects only for A9 and B12 in controls and B27 and Cw3 in patients, fewer than would be expected by chance. It is concluded that HLA Class 1 status is not an important factor in regulating mitogen responsiveness.

Human leukocyte antigens and circulating immunoglobulin levels in Indian patients with pulmonary tuberculosis

Histocompatibility antigens (-A, -B and -C loci) and circulating antibodies (IgG, IgM, IgA and IgE) were studied in 63 pulmonary tuberculosis patients and regionally matched healthy volunteers from Uttar Pradesh, India. A previously described association with antigen B15 in an heterogeneous sample of North India was not confirmed but a slight increase of antigen B18 was found. The levels of immunoglobulins in the plasma of these patients showed a significant increase in IgG, IgA and IgE. Although the increased levels of IgG and IgA are in agreement with previous studies, the role of the increased IgE is not clear and needs further investigation. Patients who were antigen B14 and B18 positive tend to show significantly low levels of IgG, which suggests a possible genetic influence on the expression of immunoglobulin levels.

HLA antigens in Hirschsprung's disease

In 55 children with Hirschsprung's disease, 64 of their normal siblings and 120 other members of their families, HLA-A, B and C types were examined. The statistical significance of the raised incidence of A1, B14, B37 and Bw35 in the patients disappeared after correction for multiple testing. The levels of homozygosity were very similar in patients and normal controls. The results indicate no direct association of the disease with HLA type.

Multiple sclerosis, HLA, and lymphocyte surface markers

The frequencies of lymphocytes of different types in the blood of 96 multiple sclerosis patients in different phases of the disease were examined by rosetting, in relation to the HLA antigens present. In the total series of patients, there is a significant deficit of A2, and this is also suggested in the active and progressive cases, but there is no evidence of association of particular HLA haplotypes with the different phases of the disease. There was little variation among the patient categories in the frequency of T cells of different types, but patients in relapse showed a higher proportion of cells showing surface IgG. In general, there is little association of cell surface markers with HLA type, but when B8 is present there appear to be fewer E and EAC rosettes in patients in exacerbation, fewer E and IgG surface markers in remission, and more of the IgG markers in progression.

HLA antigen frequency in the Koya tribe of Andhra Pradesh, India

The frequencies of HLA-A, -B, and -C antigens were studied in a tribal population of Koya from Andhra Pradesh in southern India. No other well-defined tribal population has been studied with which the present results may be compared. However, the HLA profile of Koya showed distinct differences from the general HLA distribution in India in the frequency of a large number of antigens both at the A and B loci. This study indicates the distinctiveness of this tribal population and suggests the potential importance of the study of HLA frequencies in tribal groups of India.

HLA and syringomyelia

The HLA status of 53 patients with syringomyelia was assessed. Forty had an associated Chiari anomaly. A significant increase of HLA-A9 was found. Genetic factors may influence the development of syringomyelia.

HLA antigens and growth in diabetic children

HLA types in 121 diabetic children in Newcastle are examined in relation to their growth records. The children's height at the onset of diabetes was normal, but fell away during the course of the disease; there was low mean height velocity and failure of bone development to keep pace with chronological age. The total series shows the expected excess of HLA antigens B8, B15 and Cw3 and deficit of B7. Children with B8 are of smaller stature adjusted for bone age than those without the antigen, while children with B7 appear to do better. The results suggest that within the diabetic spectrum of genotypes the HLA antigens are relevant to growth and development.

HLA in manic-depressive psychosis

HLA types studied in 113 patients with manic-depressive psychosis did not confirm the previously suggested association with HLA Bw16. No difference was found between unipolar and bipolar manifestations. A possible excess of A10 in patients is of interest, since this antigen binds with psychotropic drugs.

Genetic factors in puerperal affective psychoses

The hypothesis that puerperal affective psychosis (PAP) is genetically related to manic-depressive disorder was tested by comparing the morbidity risks for puerperal and non-puerperal affective disorders in the relatives of 17 PAP subjects and 20 parous manic-depressives (PMD) with no history of puerperal illness. The risk for affective disorder (mania, depression or suicide) and puerperal affective disorder was the same in the two groups of relatives and the test hypothesis was accepted, although the sample size was small. The frequencies of HLA-A, B and C locus antigens, nine blood group antigens and 10 red blood cell isoenzymes were not significantly different in the PAP and PMD subjects, showing that in this series genetic markers do not distinguish puerperal from non-puerperal affective psychoses.

Congenital hypothyroidism and HLA

HLA-A, B and C antigens tested in 97 patients treated for congenital hypothyroidism, and in members of their families, are compared with normal frequencies from 635 controls. After adjustment for the number of tests, there remains in the patients only a negative association with A11, with a relative risk of .190, and no significant association in the relatives. Patients show no excess homozygosity and no deviations in haplotype frequency. Congenital hypothyroidism thus appears to show a different relationship with HLA from other thyroid disorders.

Antinuclear antibodies and histocompatibility antigens in patients on long-term lithium therapy

A survey of antinuclear factor, histocompatibility antigens, red blood cell groups and red blood cell isoenzyme variants is reported in 54 patients on long-term lithium therapy. Eleven patients with detectable antinuclear factor could not be distinguished from 43 patients without antinuclear factor using age, sex, diagnosis, previous medication, time on lithium or usual dose of lithium. The presence of antinuclear factor was not associated with any particular genetic marker.

Spinal muscular atrophy associated with HLA-B7

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A search for linkage in cystic fibrosis

Linkage between the locus for cystic fibrosis and other genetic markers was explored in 40 families from Birmingham and 20 from Manchester. No strong evidence was found for linkage with any of the markers examined. There was evidence against close linkage with ABO, HLA, and Rh.

Human leucocyte antigens in Crohn's disease and ulcerative colitis

The frequency of occurrence of 15 of the commoner human leucocyte antigens was determined in 18 patients with Crohn's disease and in 16 patients with ulcerative colitis, using an in-vitro lymphocyte cytotoxicity test (Harris, Wentzel, Cocking, Dodsworth, and Ukaejiofo, 1970). The overall results showed that, with the exception of human leucocyte antigen 3 in patients with Crohn's disease, in neither disease was there any major difference in any of the other antigen frequencies compared with a panel of 50 healthy controls. Nor was there an excess frequency of any particular antigen occurring in both Crohn's disease and colitis.