Smoothed particle hydrodynamics method applied to pulsatile flow inside a rigid two-dimensional model of left heart cavity.

This paper aims to extend the application of smoothed particle hydrodynamics (SPH), a meshfree particle method, to simulate flow inside a model of the heart's left ventricle (LV). This work is considered the first attempt to simulate flow inside a heart cavity using a meshfree particle method. Simulating this kind of flow, characterized by high pulsatility and moderate Reynolds number using SPH is challenging. As a consequence, validation of the computational code using benchmark cases is required prior to simulating the flow inside a model of the LV. In this work, this is accomplished by simulating an unsteady oscillating flow (pressure amplitude: A = 2500 N ∕ m(3) and Womersley number: W(o) = 16) and the steady lid-driven cavity flow (Re = 3200, 5000). The results are compared against analytical solutions and reference data to assess convergence. Then, both benchmark cases are combined and a pulsatile jet in a cavity is simulated and the results are compared with the finite volume method. Here, an approach to deal with inflow and outflow boundary conditions is introduced. Finally, pulsatile inlet flow in a rigid model of the LV is simulated. The results demonstrate the ability of SPH to model complex cardiovascular flows and to track the history of fluid properties. Some interesting features of SPH are also demonstrated in this study, including the relation between particle resolution and sound speed to control compressibility effects and also order of convergence in SPH simulations, which is consistently demonstrated to be between first-order and second-order at the moderate Reynolds numbers investigated.

Evaluation of shear stress accumulation on blood components in normal and dysfunctional bileaflet mechanical heart valves using smoothed particle hydrodynamics.

Evaluating shear induced hemodynamic complications is one of the major concerns in design of the mechanical heart valves (MHVs). The monitoring of these events relies on both numerical simulations and experimental measurements. Currently, numerical approaches are mainly based on a combined Eulerian-Lagrangian approach. A more straightforward evaluation can be based on the Lagrangian analysis of the whole blood. As a consequence, Lagrangian meshfree methods are more adapted to such evaluation. In this study, smoothed particle hydrodynamics (SPH), a fully meshfree particle method originated to simulate compressible astrophysical flows, is applied to study the flow through a normal and a dysfunctional bileaflet mechanical heart valves (BMHVs). The SPH results are compared with the reference data. The accumulation of shear stress patterns on blood components illustrates the important role played by non-physiological flow patterns and mainly vortical structures in this issue. The statistical distribution of particles with respect to shear stress loading history provides important information regarding the relative number of blood components that can be damaged. This can be used as a measure of the response of blood components to the presence of the valve implant or any implantable medical device. This work presents the first attempt to simulate pulsatile flow through BMHVs using SPH method.

Comparison of the COHIP and OHIP- 14 as measures of the oral health-related quality of life of adolescents.

AIM: To compare the validity and reliability of the Oral Health Impact Profile-14 (OHIP-14) and the Child Oral Health Impact Profile (COHIP) for investigating oral health related quality of life (OHRQoL) of adolescents. METHOD: We studied 234 adolescents from two publicly funded schools in Hamedan, Iran. Participants completed questionnaires and had a clinical examination. We compared convergent and discriminative validity of the instruments by analyzing their association with self reported health indicators and number of decayed teeth. RESULTS: Both instruments showed good convergence with self-rated health and self-rated oral health. Those who perceived dental treatment needs, who had experienced dental pain in last month, were more dissatisfied with their oral health, or had more decayed teeth scored higher on both OHIP-14 and COHIP. The discriminative validity of the two instruments varied slightly and inconsistently. The convergent and discriminative validity of both instruments were established independent of their scoring methods. CONCLUSION: Both the OHIP-14 and COHIP were valid and reliable measures for investigating OHRQoL among 15-17 year old adolescents. The COHIP is preferable when the aim is identifying more impacts. Both measures have shown good convergent and discriminative validity, however, for practical reasons; the shorter instrument (OHIP-14) may be more suitable for epidemiological studies.

Assaying the presence of histone-like protein HU in Halobacillus karajensis.

Histone-Like Proteins (HLPs) in bacteria are small basic proteins that contribute to the control of gene expression, recombination, DNA replication and compressing the bacterial DNA in the nucleoid. Among the HLPs, HU protein as a dimer plays an important role in binding to DNA and bending it. In this study, we showed that a 9.5-10 kDa protein with the same electrophoretic mobility as HU exists in Halobacillus karajensis which is a novel gram positive moderate halophile bacterium that was recently isolated from surface saline soil of the Karaj Region, Iran. The genes encoding HU protein were also assayed during this study by Polymerase Chain Reaction.

Transient leukaemia cutis in hairy-cell leukaemia.

Leukaemic skin infiltration is uncommon in hairy-cell leukaemia (HCL), a neoplasm characterized by the presence of uniform mononuclear cells with cytoplasmic projections in the blood, bone marrow and spleen. A case is reported in which leukaemia cutis was a transient phenomenon, appearing soon after the onset of a continuous pyrexia associated with marked systemic upset which was subsequently shown to be due to pulmonary tuberculosis.

Coeliac disease and pernicious anaemia.

Despite the often reported autoimmune basis for coeliac disease and pernicious anaemia, there have been only occasional reports of the two conditions occurring together. We wish to report of such an association occurring in a 61 year old patient and comment on the diagnostic and prognostic implications.

Chronic T cell lymphocytosis: a review of 21 cases.

Twenty-one patients are described with a proliferation of morphologically mature T lymphocytes. The clinical course was chronic in most, and splenic enlargement the main clinical finding; skin involvement and lymphadenopathy were rare. The mean lymphocyte count at presentation was 8 X 10(9)/1 (range 0.75-24 X 10(9)/1). Nineteen of these patients showed some form of cytopenia (18 neutropenia, two red cell aplasia, eight thrombocytopenia) and one had hypogammaglobulinaemia. Seven patients had long-standing arthropathy serologically proven to be rheumatoid arthritis and these had previously been considered to have Felty's syndrome. Five of the group have died (three with an aggressive course), but most have remained stable for prolonged periods with a slow increase in peripheral lymphocyte count and marrow infiltration. Spontaneous regression was never observed but in two patients a prolonged remission was achieved by chemotherapy. The lymphocytes were morphologically and phenotypically homogeneous at presentation and remained so post-splenectomy; they contained azurophilic granules, stained with acid phosphatase but weakly or not at all with alpha napthyl acetate esterase. Membrane phenotyping shows the majority of the cells to be E+, Fc gamma+, OKT3+, OKT8+. Most cells do not stain with OKT1-like reagents and a significant number express HLA-Dr. From these and other reported cases it is clear that this condition represents a distinct entity resulting from the expansion of a subset of cytotoxic/suppressor T cells--the question of the benign or neoplastic nature of the disease remains open. Using T cell-specific antisera and E-rosetting techniques, a small percentage of CLL cases have been shown to be of T-cell origin (TCLL) (Dickler et al, 1973; Lille et al, 1973). Estimates of the percentage vary but in most series T-CLL has been diagnosed in less than 5% (Brouet & Seligmann, 1981), and this is supported by date from the M.R.C. Leukaemia Unit which found T-CLL in only 1.5% of 600 cases of CLL examined by marker studies (D. Catovsky, unpublished). Amongst the published reports of T-CLL a variety of clinical and morphological entities have been described including T prolymphocytic leukaemia (TPLL) (Brouet et al. 1975) and adult T cell disease in Japanese (Uchiyama et al, 1977) and West Indian Caribbean groups (ATLL) (Catovsky et al, 1982). In the original series of Brouet & Seligmann (1981) the group was defined as presenting in middle age with marked hepatosplenomegaly, some lymphadenopathy, skin involvement and with an aggressive disease course; peripheral blood and marrow lymphocytosis were variable.(ABSTRACT TRUNCATED AT 400 WORDS)