Biotribological behaviour, biodegradability and osteocompatibility of Mg-3Zn/HA composite based intramedullary inserts in avian model.

Bioactivity, structural integrity and tribological behaviour of biodegradable orthopaedic fracture fixing accessories considerably impact their actual performance in the body environment. Immune system in the living body quickly responds to the wear debris as foreign material and begins a complex inflammatory response. Magnesium (Mg) based biodegradable implants are widely studied for temporary orthopaedic applications, due to their similar elastic modulus and density to natural bones. However, Mg is highly vulnerable to corrosion and tribological damage in actual service conditions. To address these challenges via a combined approach, the Mg-3 wt% Zinc (Zn)/x hydroxyapatite (HA, x = 0, 5 and 15 wt%) based composites (fabricated via spark plasma sintering route) are evaluated in terms of biotribocorrosion and in-vivo biodegradation and osteocompatibility behaviour in an avian model. The addition of 15 wt% HA in the Mg-3Zn matrix has significantly enhanced the wear and corrosion resistance in the physiological environment. X-ray radiograph analysis of the Mg-HA-based intramedullary inserts implanted in the humerus bone of birds showed consistent progression of degradation and positive tissue response up to 18 weeks. The 15 wt% HA reinforced composites have shown better bone regeneration properties than other inserts. This study provides new insights into developing next-generation Mg-HA-based biodegradable composites for temporary orthopaedic implants, with excellent biotribocorrosion behaviour.

Numerical assessment of hemodynamic perspectives of a left ventricular assist device and subsequent proposal for improvisation.

Due to the unavailability of donors, the use of left ventricular assist devices has emerged to be a reliable line of alternative treatment for heart failure. However, ventricular assist devices (VAD) have been associated with several postoperative complications such as thrombosis, hemolysis, etc. Despite considerable improvements in technology, blood trauma due to high shear stress generation has been a major concern that is largely related to the geometrical feature of the VAD. This study aims to establish the design process of a centrifugal pump by considering several variations in the geometrical feature of a base design using the commercial solver ANSYS-CFX. To capture the uncertain behavior of blood as fluid, Newtonian, as well as non-Newtonian (Bird-Carreau model), models are used for flow field prediction. To assess the possibility of blood damage maximum wall shear stress and hemolysis index have been estimated for each operating point. The results of the simulations yield an optimized design of the pump based on parameters like pressure head generation, maximum shear stress, hydraulic efficiency, and hemolysis index. Further, the design methodology and the steps of development discussed in the paper can serve as a guideline for developing small centrifugal pumps handling blood.

Effect of left ventricular assist device on the hemodynamics of a patient-specific left heart.

This article describes the numerical efforts made to investigate the influence of a left ventricular assist device (LVAD) on the patient-specific left heart's hemodynamics. Two different computational geometries with left heart have been simulated over the entire cardiac cycle (case 1: healthy heart without LVAD and case 2: diseased heart with LVAD). The blood flow was simulated by implementing Bird-Carreau non-Newtonian model. Simulation results show that implantation of LVAD pump imparts major influence on the hemodynamics of the heart; it also provides a cardiac output of 4.87 L/min even at the diastolic phase. Furthermore, post LVAD implantation, approximately eight times more wall shear stress, is noticed at the aorta during the ventricular systole. In particular, major changes in the fluidics are observed inside the aortic region. A possibility of flow stagnation is noticed near the aortic root during the diastolic phase due to the bisection of incoming bloodstreams from the outflow graft. The flow characteristics of the LVAD pump are also observed to be significantly different from the idealized simulations (idealized tubular inlet situation). The observation of this study can help in understanding post-implant critical hemodynamic issues due to pump performance and its subsequent impact on the heart. A simulation approach-based study has been performed to investigate the influence of LVAD on the hemodynamics of a heart. A 3D computational model of a patient-specific heart has been created from CT scan datasets for diastole and systole phases (a). An axial flow blood pump has been implanted computationally into the left heart (b). The implanted blood pump enhances the cardiac output and elevates shear generation (c) and (d).

Comparative assessment of different versions of axial and centrifugal LVADs: A review.

Continuous-flow left ventricular assist devices (LVADs) have gained tremendous acceptance for the treatment of end-stage heart failure patients. Among different versions, axial flow and centrifugal flow LVADs have shown remarkable potential for clinical implants. It is also very crucial to know which device serves its purpose better to treat heart failure patients. A thorough comparison of axial and centrifugal LVADs, which may guide doctors in deciding before the implant, still lacks in the literature. In this work, an assessment of axial and centrifugal LVADs has been made to suggest a better device by comparing their engineering, clinical, and technological development of design aspects. Hydrodynamic and hemodynamic aspects for both types of pumps are discussed along with their biocompatibility, bearing types, and sizes. It has been observed numerically that centrifugal LVADs perform better over axial LVADs in every engineering aspect like higher hydraulic efficiency, better characteristics curve, lesser power intake, and also lesser blood damage. However, the clinical outcomes suggest that centrifugal LVADs experience higher events of infections, renal, and respiratory dysfunction. In contrast, axial LVADs encountered higher bleeding and cardiac arrhythmia. Moreover, recent technological developments suggested that magnetic type bearings along with biocompatible coating improve the life of LVADs.

Biocompatibility and biodegradability evaluation of magnesium-based intramedullary bone implants in avian model.

At present days osteosynthesis modalities for avian fracture management are inadequate. External coaptation is the most practiced method however, specialized clinics have started introducing intramedullary pinning, external skeletal fixation with tie-in-fixation for fracture immobilization. Magnesium (Mg) based biomaterials are trustable developments in the field of orthopedics compared to their permanent stainless steel counterparts concerning long term adverse reaction. Mg implants are becoming promising for their use as intramedullary accessories because they are bioresorbable with high strength-weight ratio and the similarities in density and elastic modulus to the natural bones. However, their severe biodegradation trait restricts frequent use as load-bearing orthopedic implants. In this study, the biocompatibility and biodegradability of Mg based intramedullary cylindrical spacers (2.4 mm diameter × 8 mm height) reinforced with 0, 5, 15 wt% of hydroxyapatite (HA, Ca10 (PO4 )6 (OH)2 ) were evaluated in 18 Uttara-fowl birds. Clinical, radiological (from immediate postoperative days till 24th week), biochemical (first three postoperative weeks) and histopathological study of test bone were carried out to evaluate implant degradation and osteocompatibility. Biodegradation of Mg-3Zn/0HA and Mg-3Zn/15HA initiated a bit earlier at second week of implantation, while that of Mg-3Zn/5HA at 3-fourth week, and found biocompatible and biodegradable with no observable clinical and histopathological changes.

Simulation of Blood as Fluid: A Review From Rheological Aspects.

Blood flow in the human vascular system is a complex to understand example of fluid dynamics in a closed conduit. Any irregularities in the hemodynamics may lead to lethal cardiovascular disease like heart attack, heart failure and ischemia. Numerical simulation of hemodynamics in the blood vessel can facilitate a thorough understanding of blood flow and its interaction with the adjacent vessel wall. A good simulation approach for blood flow can be helpful in early prediction and diagnosis of the mentioned disease. The simulation outcomes may also provide decision support for surgical planning and medical implants. This study reports an extensive review of various approaches adopted to analyze the influence of blood rheological characteristics in a different class of blood vessels. In particular, emphasis was given on the identification of best possible rheological model to effectively solve the hemodynamics inside different blood vessels. The performance capability of different rheological models was discussed for different classes and conditions of vessels and the best/poor performing models are listed out. The Carreau, Casson and generalized power-law models were appeared to be superior for solving the blood flow at all shear rates. In contrast, power law, Walburn-Scheck and Herchel-Bulkley model lacks behind in the purpose.

Numerical simulation of centrifugal and hemodynamically levitated LVAD for performance improvement.

Left ventricular assist device (LVAD) provides an effective artificial support system to the heart patients. Despite the improved life survival rate, complications like hemolysis, blood trauma, and thrombus formation still limit the performance of the blood pump. The geometrical aspects of blood pumps majorly influence the hemodynamics, therefore these devices must be carefully engineered. In this work, several versions of centrifugal blood pumps are simulated using ANSYS-CFX to propose a best compatible design for LVAD. A hemodynamic levitation approach for the impeller is also suggested to overcome the cost and weight issue associated with the magnetic levitation. The blood flow is modeled by implementing Bird-Carreau model and its turbulence is solved using the SST turbulence model. The influence of the blade profile, blade tip width, blade numbers, and splitter blades on the hemodynamic characteristics through the pump is observed. An optimum design of centrifugal blood pump for the assistance of failed ventricle is proposed that can effectively pump the blood from the left ventricle to the ascending aorta. The proposal can be adopted by LVAD designers to have hemodynamically tuned efficient product.

Proposal of hemodynamically improved design of an axial flow blood pump for LVAD.

Left ventricular assist devices (LVAD) emerges as an effective clinical device providing life-saving support to heart patients. The design of blood pump of an LVAD involves incredible accuracy and thorough understanding of hemodynamics to mimic the functionality of a healthy ventricle. This work studies hemodynamics around an LVAD and proposes an improved model of axial blood pump for cardiac circulation without any hemolysis complications through numerical investigations. A three-dimensional study on different versions of the impeller with three curved blades (pump I) and spiral blade (pump II) is carried out by utilizing computational fluid dynamics software ANSYS-CFX at a range of rotational speeds and flow rates. The non-Newtonian blood flow through pump is modeled by using Bird-Carreau model. To capture the change in the flow field near the rotating blade, a transient blade row model was employed. The proposal of spiral blade impeller was found to be more compatible as per the hemolytic performance. It considerably reduces the blood damage to two times lesser value than that by pump I and also improves the quality blood flow field. The spiral blade provides a guiding path to the blood particle and avoids mixing of different bloodstreams, thus reducing the eddy losses. Graphical abstract The graphical abstract shows the performance enhancement of the axial blood pump. The model proposed by Peng et al. (Comput Methods Biomech Biomed Engin 17(7):723-727, 2014) has been upgraded to two new versions by redesigning its impeller. Proposed design (pump II) shows improvement in pressure distribution (a) and reduction in hemolysis (in the case of pump II) index (b).

Discordance in self-report and observation data on mistreatment of women by providers during childbirth in Uttar Pradesh, India.

BACKGROUND: The study aims to assess the discordance between self-reported and observed measures of mistreatment of women during childbirth in public health facilities in Uttar Pradesh, India, as well as correlates of these measures and their discordance. METHODS: Cross sectional data were collected through direct observation of deliveries and follow-up interviews with women (n = 875) delivering in 81 public health facilities in Uttar Pradesh. Participants were surveyed on demographics, mistreatment during childbirth, and maternal and newborn complications. Provider characteristics (training, age) were obtained through interviews with providers, and observation data were obtained from checklists completed by trained nurse investigators to document quality of care at delivery. Mistreatment was assessed via self-report and observed measures which included 17 and 6 items respectively. Cohen's kappas assessed concordance between the 6 items common in the self-report and observed measures. Regression models assessed associations between characteristics of women and providers for each outcome. RESULTS: Most participants (77.3%) self-reported mistreatment in at least 1 of the 17-item measure. For the 6 items included in both self-report and observations, 9.1% of women self-reported mistreatment, whereas observers reported 22.4% of women being mistreated. Cohen's kappas indicated mostly fair to moderate concordance. Regression analyses found that multiparous birth (AOR = 1.50, 95% CI = 1.06-2.13), post-partum maternal complications (AOR = 2.0, 95% CI = 1.34-3.06); new-born complications (AOR = 2.6, 95% CI = 1. 96-4.03) and not having an Skilled Birth Attendant (SBA) trained provider (AOR = 1.47, 95% CI = 1.05-2.04) were associated with increased risk for mistreatment as measured by self-report. In contrast, only provider characteristics like older provider (AOR = 1.03, 95% CI = 1.02-1.05) and provider not trained in SBA (AOR = 1.44, 95% CI = 1.02-2.02) were associated with mistreatment as measured through observations. Younger age at marriage (AOR = 0.86, 95% CI = 0.78-0.95) and provider characteristics (older provider AOR = 1.05, 95% CI = 1.01-1.09; provider not trained in SBA AOR = 0.96, 95% CI = 0.92-0.99) were associated with discordance (based on mistreatment reported by observer but not by women). CONCLUSION: Provider mistreatment during childbirth is prevalent in Uttar Pradesh and may be under-reported by women, particularly when they are younger or when providers are older or less trained. The findings warrant programmatic action as well as more research to better understand the context and drivers of both behavior and reporting. TRIAL REGISTRATION: CTRI/2015/09/006219. Registered 28 September 2015.

Canine Parvovirus ns1 gene and Chicken Anemia vp3 gene induce partial oncolysis of Canine Transmissible Venereal Tumor.

The oncolytic effect of Canine Parvovirus ns1 gene and Chicken Anemia vp3 gene in naturally occurring cases of Canine Transmissible Venereal Tumor (CTVT) is being reported. Dogs suffering from CTVT (N = 18) were systematically randomized into three groups viz. A, B, and C (n = 6). Animals of the groups A, B, and C received 100 µg of the ns1 gene, vp3 gene, and ns1 + vp3 gene combination, respectively, for three weeks intratumorally at weekly intervals; results were normalized against base values before commencement of therapy and after complete remission that were taken as negative and positive controls, respectively. Initiation of oncolytic gene therapy arrested the further progression of the tumor but most of the animals in the study underwent incomplete remission, indicating incomplete activity of ns1 and vp3 genes. The oncolytic effect of the treatments was in the order ns1 > vp3 > ns1 + vp3. Oncolysis was accompanied by decreased mitotic index and AgNOR count, and increased TUNEL positive cells and CD4+ lymphocyte counts. Our findings show that Canine Parvovirus ns1 may eventually find an important role as an oncolytic agent.

Associations Between Mistreatment by a Provider during Childbirth and Maternal Health Complications in Uttar Pradesh, India.

Objectives This study assesses associations between mistreatment by a provider during childbirth and maternal complications in Uttar Pradesh, India. Methods Cross-sectional survey data were collected from women (N = 2639) who had delivered at 68 public health facilities in Uttar Pradesh, participating in a quality of care study. Participants were recruited from April to July 2015 and surveyed on demographics, mistreatment during childbirth (measure developed for this study, Cronbach's alpha = 0.70), and maternal health complications. Regression models assessed associations between mistreatment during childbirth and maternal complications, at delivery and postpartum, adjusting for demographics and pregnancy complications. Results Participants were aged 17-48 years, and 30.3% were scheduled caste/scheduled tribe. One in five (20.9%) reported mistreatment by their provider during childbirth, including discrimination and abuse; complications during delivery (e.g., obstructed labor) and postpartum (e.g., excessive bleeding) were reported by 45.8 and 41.5% of women, respectively. Health providers at delivery included staff nurses (81.8%), midwives (14.0%), and physicians (2.2%); Chi square analyses indicate that women were significantly more likely to report mistreatment when their provider was a nurse rather than a physician or midwife. Women reporting mistreatment by a provider during childbirth had higher odds of complications at delivery (AOR = 1.32; 95% CI 1.05-1.67) and postpartum (AOR = 2.12; 95% CI 1.67-2.68). Conclusions for Practice Mistreatment of women by their provider during childbirth is a pervasive health and human rights violation, and is associated with increased risk for maternal health complications in Uttar Pradesh. Efforts to improve quality of maternal care should include greater training and monitoring of providers to ensure respectful treatment of patients.

Coalescence of sessile microdroplets subject to a wettability gradient on a solid surface.

While there are intensive studies on the coalescence of sessile macroscale droplets, there is little study on the coalescence of sessile microdroplets. In this paper, the coalescence process of two sessile microdroplets is studied by using a many-body dissipative particle dynamics numerical method. A comprehensive parametric study is conducted to investigate the effects on the coalescence process from the wettability gradient, hydrophilicity of the solid surface, and symmetric or asymmetric configurations. A water bridge is formed after two microdroplets contact. The temporal evolution of the coalescence process is characterized by the water bridge's radii parallel to the solid surface (W_{m}) and perpendicular to the solid surface (H_{m}). It is found that the changes of both H_{m} and W_{m} with time follow a power law; i.e., H_{m}=ß_{1}τ^{ß} and W_{m}=α_{1}τ^{α}. The growth of H_{m} and W_{m} depends on the hydrophilicity of the substrate. W_{m} grows faster than H_{m} on a hydrophilic surface, and H_{m} grows faster than W_{m} on a hydrophobic surface. This is due to the strong competition between capillary forces induced by the water-bridge curvature and the solid substrate hydrophobicity. Also, flow structure analysis shows that regardless of the coalescence type once the liquid bridge is formed the liquid flow direction inside the capillary bridge is to expand the bridge radius. Finally, we do not observe oscillation of the merged droplet during the coalescence process, possibly due to the significant effects of the viscous forces.