[Vascular age and cardiovascular risk in hypertensive patients followed at the heart institute]. / Âge vasculaire et risque cardiovasculaire chez les patients hypertendus suivis à l'institut de cardiologie d'Abidjan.

OBJECTIVE: To calculate the vascular age of hypertensive patients and assess the risk at 10 years of occurrence of an absolute cardiovascular event in outpatient consultation of the Abidjan Heart Institute. PATIENTS AND METHODOLOGY: Cross-sectional study with descriptive and analytical purposes from June 2021 to September 2021, i.e. 4 months in patients at least 30 years of age followed in the outpatient department for arterial hypertension without cardiovascular complications. Data were collected using a questionnaire. We considered the parameters established in the D'Agostino chart for the calculation of vascular age. Each parameter was weighted and the total points obtained corresponded to the vascular age. The cardiovascular risk at 10 years was also obtained from another abacus established by D'Agostino by cross-referencing the total points of each patient with pre-established data. RESULTS: Three hundred hypertensive people were included in this study. The calendar average age was 62.0 ± 10 years with extremes of 30 and 95 years. The gender distribution showed female predominance and there was no significant difference in vascular age by sex. The mean vascular age of all patients was 73.4 ± 9.9 years. The mean difference between actual and vascular age was 11.4 years. Dyslipidemia (p = 0.0002), diabetes (p = 0.0004) and unstandardized BP (p = 0.0000) significantly influenced vascular age. There was no significant difference between smokers and non-smokers (p = 0.1349). All men had a greater than 30% risk of having a cardiovascular accident while women before the age of 35 had no risk. Over the age of 60, almost all patients (both men and women) had a greater than 30% risk of having a cardiovascular accident at 10 years. CONCLUSION: The calculation of vascular age made it possible to assess arterial aging and calculate the probability at 10 years of occurrence of a cardiovascular event. This study also highlights the importance of cardiovascular risk and vascular age assessment for management adaptation and therapeutic education.

Cauda equina thickening: an approach to MRI findings.

There are many causes of cauda equina (CE) thickening on neuroimaging of the lumbar spine. The imaging features of CE thickening for the various conditions often overlap and are non-specific to clinch a definite diagnosis. Hence, the imaging findings have to be discerned in accordance with the patient's presenting history, clinical examination findings, and results from electrophysiology and laboratory studies. In this review, the authors aim to supplement the existing literature on imaging findings of CE thickening with a diagnostic framework for clinical workup. The authors also aim to familiarise readers with the interpretation of CE thickening on magnetic resonance imaging (MRI) and would like to illustrate the normal variants and pitfalls that could be mistaken for abnormal results.

Joint effect of defocus blur and spatial attention.

Defocus blur and spatial attention both act on our ability to see clearly over time. However, it is currently unknown how these two factors interact because studies on spatial resolution only focused on the separate effects of attention and defocus blurs. In this study, eleven participants performed a resolution acuity task along the diagonal 135˚/315˚ with horizontal, at 8˚ eccentricity for clear and blurred Landolt C images under various manipulations of covert endogenous attention. All the conditions were interleaved and viewed binocularly on a visual display. We observed that attention not just improves the resolution of clear stimuli, but also modulates the resolution of defocused stimuli for compensating the loss of resolution caused by retinal blur. Our results show, however, that as the degree of attention decreases, the differences between clear and blurred images largely diminish, thus limiting the benefit of an image quality enhancement. It also appeared that attention tends to enhance the resolution of clear targets more than blurred targets, suggesting potential variations in the gain of vision correction with the level of attention. This demonstrates that the interaction between spatial attention and defocus blur can play a role in the way we see things. In view of these findings, the development of adaptive interventions, which adjust the eye's defocus to attention, may hold promise.

Optical performance of progressive addition lenses (PALs) with astigmatic prescription.

The progressive addition lens (PAL) is a spectacle lens design with progressive refractive power changes across the lens surface to provide sharp vision at different viewing distances for patients with reduced accommodative strength. It has gained in popularity not just for presbyopic patients, but also patients with occupational (office, driving, or digital device) and therapeutic (e.g., myopia control) needs. However, despite the increasing prevalence of astigmatism in adults > 40 years old who rely on PAL correction, no metric is available to reflect the optical variation in PALs with astigmatic prescriptions. Based on recent studies, four novel optical metrics sensitive to variation of refractive power across the lens surface of PALs have been developed. These metrics were used to compare the optical performance of PALs of various prescriptions, designs, and manufacturers. For each lens, the refractive power profile was first measured with a Moire-deflectometry-based instrument.The data was then exported and analyzed using a two-dimensional error map for each of the four metrics. The results revealed significant impacts of astigmatic prescription, providing evidence for the usefulness of these metrics in quantifying the optical performance of PALs for patients with astigmatic prescriptions.

Testing impacts of global blur profiles using a multiscale vision simulator.

Although it is possible to specify the impact of blur at a specific retinal location, a lack of understanding exists regarding how the inhomogeneous blur distribution across the retina (i.e., global blur) affects the quality of an optical correction at a specific retinal location. To elucidate this issue, a multiscale visual simulator combining the projection of a controllable high-resolution stimulus and an ocular monitoring system was constructed to simultaneously simulate foveal and extrafoveal blurs. To define the range and capability of a wide-angle stimulation, an optimal working pupil was evaluated by optical ray-tracing via a Monte Carlo simulation, including optical variations corresponding to fixational eye movements. To investigate the impacts of global blur on the perception of discrete regions of the visual field, the bothersome blur threshold from five subjects was measured through this novel system using a collection of zonal blurs (annuli image projected sequentially at discrete retinal regions), and these impacts were compared with those using a spatially-varying blur (continuum of simultaneously projected zonal blurs of varying strengths, simulating retinal blur variations). Our results show that the zonal blur threshold does not entirely predict the global blur threshold, having a tendency to overestimate blur the threshold. It was concluded that, in addition to the amount of defocus present at a defined retinal location, the perception of individual defocused retinal regions can be affected by global blur. Given that blur tolerance can affect the perception of optically induced blurs, the findings provide useful implications for designing new optical correction.

Informing Precision Home Visiting: Identifying Meaningful Subgroups of Families Who Benefit Most from Family Spirit.

The Maternal, Infant, and Early Childhood Home Visiting Program was reauthorized February 8, 2018, and invests $2 billion over 5 years to improve mothers' and children's outcomes across the life course. Along with this investment, the home-visiting field is striving for implementation innovations to deliver the greatest impact to the most families at the most efficient cost through a focus on precision home visiting. Consistent with the precision home-visiting approach to identify meaningful subgroups to guide content tailoring, the purpose of this paper is to answer (1) how and to what degree an evidence-based home-visiting model benefits mothers and children with substance use or depression and (2) what baseline characteristics indicate who can benefit most. We completed a secondary data analysis of the most recently completed randomized controlled trial (RCT) of Family Spirit (N = 322), a federally endorsed home-visiting intervention designed for young Native American mothers and their children. We examined how baseline differences in mothers' substance use, depression, and demographic characteristics (household mobility, education, parity, and premature birth) moderated mothers' and children's intervention-related outcomes. Children born to mothers with past substance use histories benefited more from the intervention than children born to abstinent mothers (p < 0.01). Unstable housing, parity, and low educational attainment emerged as moderators of intervention effectiveness. Results from this investigation will serve as a basis for designing and evaluating a precision approach to Family Spirit and may provide lessons for other models to explore tailoring variables for optimal impact and efficiency. Trial Registry: NCT00373750.

Validity of self-reported weight and height: a cross-sectional study among Malaysian adolescents.

BACKGROUND: Self-reported weight and height are commonly used in lieu of direct measurements of weight and height in large epidemiological surveys due to inevitable constraints such as budget and human resource. However, the validity of self-reported weight and height, particularly among adolescents, needs to be verified as misreporting could lead to misclassification of body mass index and therefore overestimation or underestimation of the burden of BMI-related diseases. The objective of this study was to determine the validity of self-reported weight and height among Malaysian secondary school children. METHODS: Both self-reported and directly measured weight and height of a subgroup of 663 apparently healthy schoolchildren from the Malaysian Adolescent Health Risk Behaviour (MyAHRB) survey 2013/2014 were analysed. Respondents were required to report their current body weight and height via a self-administrative questionnaire before they were measured by investigators. The validity of self-reported against directly measured weight and height was examined using intraclass correlation coefficient (ICC), the Bland-Altman plot and weighted Kappa statistics. RESULTS: There was very good intraclass correlation between self-reported and directly measured weight [r = 0.96, 95% confidence interval (CI): 0.93, 0.97] and height (r = 0.94, 95% CI: 0.90, 0.96). In addition the Bland-Altman plots indicated that the mean difference between self-reported and direct measurement was relatively small. The mean difference (self-reported minus direct measurements) was, for boys: weight, -2.1 kg; height, -1.6 cm; BMI, -0.44 kg/m2 and girls: weight, -1.2 kg; height, -0.9 cm; BMI, -0.3 kg/m2. However, 95% limits of agreement were wide which indicated substantial discrepancies between self-reported and direct measurements method at the individual level. Nonetheless, the weighted Kappa statistics demonstrated a substantial agreement between BMI status categorised based on self-reported weight and height and the direct measurements (kappa = 0.76, 95% CI: 0.67, 0.84). CONCLUSION: Our results show that the self-reported weight and height were consistent with direct measurements and therefore can be used in assessing the nutritional status of Malaysian school children from the age of 13 to 17 years old in epidemiological studies and for surveillance purposes when direct measurements are not feasible, but not for assessing nutritional status at the individual level.

Rapid determination of sildenafil and its analogues in dietary supplements using gas chromatography-triple quadrupole mass spectrometry.

Application of gas chromatography-triple quadrupole mass spectrometry for identification, confirmation and quantification of 6 phosphodiesterase-5 (PDE-5) inhibitors (sildenafil, dimethylsildenafil, homosildenafil, thiosildenafil, thiodimethylsildenafil and thiohomosildenafil) in dietary supplements was investigated. The MS was operated in multiple reaction monitoring mode, for better sensitivity and selectivity. In this manner, the method is adequate to reduce background noise with less interference from co-eluting compounds in the samples. Two different ionisation techniques, electron ionisation (EI) and chemical ionisation (CI), were studied and compared. The chromatographic separation was performed on a short 10 m non-polar capillary column without any derivatisation step. This permitted fast analysis for all analogues with retention time less than 11 min, for both techniques. Use of backflushing can aid method retention time reduction and improves column maintenance. Evaluation of method validation included limit of detection (LOD), lower limit of quantitation (LLOQ), linearity, precision and recovery were performed for both EI and CI techniques. The LOD obtained varied from 0.03 to 1.50 µg/g and the LLOQ ranged from 0.10 to 5.00 µg/g. Good calibration linearity was obtained for all analogues for both techniques, with correlation coefficients (r(2)) higher than 0.99. Mean recoveries of all analogues using CI show higher values (83.4-108.8%) than that of EI (61.9-91.1%). The intra- and inter-assay precisions were evaluated for all analogues at spiked concentration of 10 µg/g and the relative standard deviation was less than 15% for both methods. These methods were then successfully applied to dietary supplement samples without prior derivatisation, confirming that the samples were adulterated with sildenafil and/or its analogues.

Melioidosis: Overview of seropositivity in Malaysia.

INTRODUCTION: Melioidosis is endemic in Malaysia but prevalence data is limited. METHODOLOGY: In this cross-sectional study, sera suspected for melioidosis were received from local hospitals from year 2013 to 2014. These data were grouped into different age groups with more focus in children aged <15 years old. RESULTS: Children <15 years old were more exposed to Burkholderia pseudomallei [Adjusted Odds ratio (AOR)=4.71, 95% Confidence Interval (CI): 4.04, 5.50) compared to the other age groups. Females, instead of males, had a slightly higher risk for melioidosis. There were more seropositive cases against melioidosis in eastern coast states (Kelantan, Terengganu, Pahang) and Sarawak. Sabah natives and nonMalaysians had higher risk of exposure to B. pseudomallei. CONCLUSION: Age group and region were independent risk factors for exposure against B. pseudomallei. Paediatric melioidosis is of concern and a marker against intensity of exposure.

Effect of laser suture lysis on filtration openings: a prospective three-dimensional anterior segment optical coherence tomography study.

PURPOSE: To investigate the effects of laser suture lysis (LSL) on filtration openings after trabeculectomy. METHODS: Prospective study analyzing the changes in the location and width of filtration openings, fluid cavity height, total bleb height, bleb wall thickness, and bleb wall intensity before and after LSL using three-dimensional anterior segment optical coherence tomography (3D AS-OCT). RESULTS: Fourteen patients had clear scleral flap image analysis. As five patients underwent LSL twice and two patients underwent LSL thrice, 23 comparison studies were possible. After LSL the intraocular pressure (IOP) decreased (P = 0.0015) from 20.5 ± 5.3 to 14.9 ± 6.4 mm Hg, and the fluid cavity height increased significantly from 0.2 ± 0.2 mm to 0.3 ± 0.1 mm (P = 0.0094). Other bleb parameters were not significantly different when comparing before and after LSL. When the IOP reduction ratio was > 25% following LSL, the width of the filtration openings on the LSL side, the total bleb height, and the fluid cavity height increased (P = 0.0273, 0.0342, and 0.0024, respectively). In multiple regression analysis the changes in fluid cavity height, the wall thickness, the wall intensity, and the width of the filtration opening were positively associated with the IOP reduction rate (P = 0.0428, 0.0226, 0.0420, and 0.0356, respectively). CONCLUSIONS: 3D AS-OCT allowed a detailed examination of the internal morphology of filtration blebs and openings before and after LSL. The changes in the internal morphology were closely associated with the success of LSL to decrease IOP.

The discriminative ability of waist circumference, body mass index and waist-to-hip ratio in identifying metabolic syndrome: Variations by age, sex and race.

OBJECTIVES: Many studies have suggested that there is variation in the capabilities of BMI, WC and WHR in predicting cardiometabolic risk and that it might be confounded by gender, ethnicity and age group. The objective of this study is to examine the discriminative abilities of body mass index (BMI), waist circumference (WC) and waist-hip ratio (WHR) to predict two or more non-adipose components of the metabolic syndrome (high blood pressure, hypertriglyceridemia, low high density lipoprotein-cholesterol and high fasting plasma glucose) among the adult Malaysian population by gender, age group and ethnicity. METHODS: Data from 2572 respondents (1044 men and 1528 women) aged 25-64 years who participated in the Non Communicable Disease Surveillance 2005/2006, a population-based cross sectional study, were analysed. Participants' socio-demographic details, anthropometric indices (BMI, WC and WHR), blood pressure, fasting lipid profile and fasting glucose level were assessed. Receiver operating characteristics curves analysis was used to evaluate the ability of each anthropometric index to discriminate MetS cases from non-MetS cases based on the area under the curve. RESULTS: Overall, WC had better discriminative ability than WHR for women but did not perform significantly better than BMI in both sexes, whereas BMI was better than WHR in women only. Waist circumference was a better discriminator of MetS compared to WHR in Malay men and women. Waist circumference and BMI performed better than WHR in Chinese women, men aged 25-34 years and women aged 35-44 years. CONCLUSIONS: The discriminative ability of BMI and WC is better than WHR for predicting two or more non-adipose components of MetS. Therefore, either BMI or WC measurements are recommended in screening for metabolic syndrome in routine clinical practice in the effort to combat cardiovascular disease and type II diabetes mellitus.

Comparison of visual field progression between temporally tilted disc and nontilted disc, in patients with normal tension glaucoma.

PURPOSE: To investigate the long-term visual field (VF) progression of temporally tilted disc and nontilted disc in normal tension glaucoma (NTG). METHODS: Retrospective, observational case series. Forty-seven patients with temporally tilted disc (47 eyes), 44 patients with nontilted disc in NTG (44 eyes) patients, who were examined by at least 5 VF tests, and were followed-up over a 5-year period, at the Department of Ophthalmology of the Samsung Medical Center, from May 1998 to 2013. VF progression was defined by modified Anderson-Hodapp criteria, and Glaucoma Progression Analysis (GPA). Multivariate analysis was used to identify the risk factors for VF progression in the temporally tilted disc. RESULTS: According to the Anderson-Hodapp criteria, progression rates of the temporally tilted disc and nontilted disc at 60 months were 19% and 72%, respectively (P<0.0001). According to GPA, they were 25% and 53%, respectively (P<0.0001). Twenty of 47 patients in the temporally tilted disc did not show progression. Among them, the more tilted disc showed the more VF defects. The hazard ratio of retinal nerve fiber layer (RNFL) defect type was 3.08 (95% CI, 1.17-8.14; P=0.02). The simultaneous superior and inferior RNFL defect type was the most common in progressors in the temporally tilted disc (P=0.04). CONCLUSION: Through long-term follow-up, the cumulative survival rate of temporally tilted disc was higher than that of nontilted disc. Caution is required in the treatment of the temporally tilted disc. New treatment policy for the temporally tilted disc may follow.

Longitudinal analysis of age-related changes in intraocular pressure in South Korea.

PURPOSE: To assess the changes in intraocular pressure (IOP) with age in South Korea. METHODS: Subjects aged 20-79 who had been receiving health examinations at a university hospital were enrolled. They completed physical and ophthalmic examinations. Subjects with ocular disease that could possibly affect their IOP were excluded. The relationships between IOP and age, blood pressure, heart rate, body mass index, blood chemistry, and electrolyte were analyzed using a linear mixed model. RESULTS: Of the 33 712 subjects, 31 857 participants were enrolled. In a cross-sectional analysis, IOP also showed a negative correlation in all age groups (respectively, P<0.001). In particular, patients in their 60s~80s had a less steep decreasing slope of IOP with age than patients in their 20s~30s (correlation coefficient -0.260 and -0.168, respectively). In longitudinal analysis, negative trend was shown in the slope of tendency in total subjects. When analyzing the effect of gender on the relationship between age and IOP, females had a less steep decreasing slope of IOP with age than males by 0.05 mm Hg. With regard to systemic parameters, systolic blood pressure and heart rate were positively correlated with IOP (P<0.001). CONCLUSION: IOP was significantly decreased with age, although the amount of change was small. In women and older age groups, IOP was less decreased than that of men and young age groups. In addition, IOP was positively associated with systolic blood pressure and heart rate.

Optimal waist circumference cut-off values for predicting cardiovascular risk factors in a multi-ethnic Malaysian population.

INTRODUCTION: Previous studies have proposed the lower waist circumference (WC) cutoffs be used for defining abdominal obesity in Asian populations. OBJECTIVE: To determine the optimal cut-offs of waist circumference (WC) in predicting cardiovascular (CV) risk factors in the multi-ethnic Malaysian population. METHODS: We analysed data from 32,703 respondents (14,980 men and 17,723 women) aged 18 years and above who participated in the Third National Health and Morbidity Survey in 2006. Gender-specific logistic regression analyses were used to examine associations between WC and three CV risk factors (diabetes mellitus, hypertension, and hypercholesterolemia). The Receiver Operating Characteristic (ROC) curves were used to determine the cut-off values of WC with optimum sensitivity and specificity for detecting these CV risk factors. RESULTS: The odds ratio for having diabetes mellitus, hypertension, and hypercholesterolemia, or at least one of these risks, increased significantly as the WC cut-off point increased. Optimal WC cut-off values for predicting the presence of diabetes mellitus, hypertension, hypercholesterolemia and at least one of the three CV risk factors varied from 81.4 to 85.5 cm for men and 79.8 to 80.7 cm for women. CONCLUSIONS: Our findings indicate that WC cut-offs of 81 cm for men and 80 cm for women are appropriate for defining abdominal obesity and for recommendation to undergo cardiovascular risk screening and weight management in the Malaysian adult population.

The prevalence of physical activity and its associated factors among Malaysian adults: findings from the National Health and Morbidity Survey 2011.

OBJECTIVES: Despite the health-enhancing benefits of physical activity, a large segment of the Malaysian population does not engage in regular physical activity at the recommended level. This study aimed to determine physical activity patterns and the associated sociodemographic correlates of physical activity. STUDY DESIGN: Data on physical activity were obtained from the National Health and Morbidity Survey (NHMS) 2011, a nationally representative, population-based cross-sectional study. A two-stage stratified sampling method was used to select a representative sample of Malaysian adults aged 16 years and above. METHODS: A total of 19,145 adults aged 16 years and above were recruited, and face-to-face interviews were conducted using the International Physical Activity Questionnaire (IPAQ), short version. The correlates for physical activity were identified using multivariate analysis. RESULTS: In this study, 64.3% (95%CI: 63.1-65.5) of Malaysian adults aged 16 and above were physically active, but overall physical activity levels decreased with advancing age. Men, rural residents, 'other' ethnic groups, and married women were more likely to demonstrate higher levels of physical activity. CONCLUSION: Approximately 65% of Malaysian adults were physically active. However, it is recommended that health promotions for active lifestyles should be targeted to the least active segments, which constitute more than a quarter of the Malaysian population.

Initial central scotomas vs peripheral scotomas in normal-tension glaucoma: clinical characteristics and progression rates.

PURPOSE: To investigate clinical characteristics and progression rates of the initial central scotomas (ICS) compared with the initial peripheral scotomas (IPS) in normal-tension glaucoma (NTG) patients. METHODS: Among NTG patients showing a single hemifield defect and who performed more than five reliable standard visual field (VF) tests, medical records of ICS (involvement of ≥3 adjacent points with P<5% within the central 12° of fixation and one point with a P<0.01 within the central 6° of fixation) (n=32) or IPS (no VF abnormality within the central 6° of fixation) (n=34) were retrospectively analyzed. The changes of mean thresholds from 10 zones of the glaucoma hemifield test, central 6° and 12° zones, peripheral zones other than central 6° and 12°, and the entire hemifield were inspected. To calculate the progression rates, linear mixed-effect model was employed. RESULTS: There were no significant differences between the two groups in age, gender, ocular factors including baseline/mean treated intraocular pressure, and systemic factors including systolic or diastolic blood pressure/perfusion pressure, mean ocular perfusion pressure (all P>0.05). There were no significant differences in baseline mean deviation and pattern standard deviation (P>0.05) between the two groups, but VF index was significantly lower in ICS group than in IPS group (P=0.001). The progression rates between the two groups were not significantly different in all zones we investigated (all P>0.05). CONCLUSIONS: Newly diagnosed cases of NTG with ICS may not differ from those with IPS in clinical characteristics and progression rates under treatment.

Coexistence of congenital giant melanocytic nevus of the scalp with cranial defect, poliosis, and hair loss.

Congenital melanocytic nevi (CMN) are pigmented lesions presenting on the skin in approximately 1% of all newborns at or shortly after birth. CMN have been described as being associated with several anomalies, including cranial bone hypertrophy, scoliosis, and spina bifida. This is the first report to describe a giant congenital melanocytic nevus on the scalp associated with cranial involvement, poliosis, and alopecia.

Characteristics of patients with a localized retinal nerve fiber layer defect and normal optic disc appearance.

PURPOSE: To investigate the characteristics of patients with a localized retinal nerve fiber layer (RNFL) defect and normal optic disc appearance compared with normal tension glaucoma (NTG) patients. METHODS: A total of 40 patients with an unchanged RNFL defect for more than 5 years and normal optic disc appearance, who were presumed as non-glaucomatous patients, were enrolled (group A). We recruited 40 age-matched patients with NTG (group B). On the RNFL photographs, we evaluated angles of RNFL defects. Angle α and ß were the angles made by the line 'L' from the center of the fovea to the disc center and the lines 'A' and 'B' from the disc center to the disc margin where the proximal and the distal border of the defect met, respectively. Angle θ was the angular width of the defect. Angle γ was the angle made by lines 'L' and 'R', which divides angle θ into a 2 :1 ratio from line 'A' to line 'B'. We compared systemic diseases, baseline IOP, and location and angles of the RNFL defects between the two groups. RESULTS: Systemic diseases and superotemporal RNFL defects in group A were significantly greater than those in group B (P<0.001). Angle α was greater in group A, but angle ß, θ, and γ were smaller in group A (P<0.05). CONCLUSION: If the patients with a superotemporal RNFL defect and normal optic disc appearance had systemic diseases and distal borders of the defects are closer to the macula, glaucoma is less likely.

A portable chemotaxis platform for short and long term analysis.

Flow-based microfluidic systems have been widely utilized for cell migration studies given their ability to generate versatile and precisely defined chemical gradients and to permit direct visualization of migrating cells. Nonetheless, the general need for bulky peripherals such as mechanical pumps and tubing and the complicated setup procedures significantly limit the widespread use of these microfluidic systems for cell migration studies. Here we present a simple method to power microfluidic devices for chemotaxis assays using the commercially available ALZET® osmotic pumps. Specifically, we developed a standalone chemotaxis platform that has the same footprint as a multiwell plate and can generate well-defined, stable chemical gradients continuously for up to 7 days. Using this platform, we validated the short-term (24 hours) and long-term (72 hours) concentration dependent PDGF-BB chemotaxis response of human bone marrow derived mesenchymal stem cells.