Cerebral aneurysms treated with flow-diverting stents: computational models with intravascular blood flow measurements

BACKGROUND AND PURPOSE

Computational fluid dynamics modeling is useful in the study of the hemodynamic environment of cerebral aneurysms, but patient-specific measurements of boundary conditions, such as blood flow velocity and pressure, have not been previously applied to the study of flow-diverting stents. We integrated patient-specific intravascular blood flow velocity and pressure measurements into computational models of aneurysms before and after treatment with flow-diverting stents to determine stent effects on aneurysm hemodynamics.

MATERIALS AND METHODS

Blood flow velocity and pressure were measured in peri-aneurysmal locations by use of an intravascular dual-sensor pressure and Doppler velocity guidewire before and after flow-diverting stent treatment of 4 unruptured cerebral aneurysms. These measurements defined inflow and outflow boundary conditions for computational models. Intra-aneurysmal flow rates, wall shear stress, and wall shear stress gradient were calculated.

RESULTS

Measurements of inflow velocity and outflow pressure were successful in all 4 patients. Computational models incorporating these measurements demonstrated significant reductions in intra-aneurysmal wall shear stress and wall shear stress gradient and a trend in reduced intra-aneurysmal blood flow.

CONCLUSIONS

Integration of intravascular dual-sensor guidewire measurements of blood flow velocity and blood pressure provided patient-specific computational models of cerebral aneurysms. Aneurysm treatment with flow-diverting stents reduces blood flow and hemodynamic shear stress in the aneurysm dome.

Adsorption and interaction of fibronectin and human serum albumin at the liquid-liquid interface

The goal of this work was to investigate the dynamics of human plasma fibronectin (HFN) at the oil-water interface and to characterize its interactions with human serum albumin (HSA) by total internal reflection fluorescence microscopy (TIRFM). Among key results, we observed that fibronectin adsorption at the oil-water interface is rapid and essentially irreversible, even over short time scales. This may be due to the highly flexible nature of the protein, which allows its various domains to quickly attain energetically favorable conformations. On the other hand, HSA adsorption at the oil-water interface is relatively reversible at short times, and the protein is readily displaced by fibronectin even after HSA has been adsorbed at the interface for as long as 2 h. At longer adsorption times, HSA is able to more effectively resist complete displacement by fibronectin, although we observed significant fibronectin adsorption even under those conditions. Displacement of adsorbed fibronectin by HSA was negligible under all conditions. Fibronectin also adsorbs preferentially from a mixture of HFN and HSA, even when the concentration of HSA is substantially higher. This study is relevant to such emerging research thrusts as the development of biomimetic interfaces for a variety of applications, where there is a clear need for better understanding of the effects of interfacial competition, adsorption time scales, and extent of adsorption irreversibility on interfacial dynamics.

Relationship between osteoarthritis of knee and menopause

AIM

To study the difference in the onset of osteoarthritis (OA) between males and females with respect to age and to note the relationship between OA of the knees and menopause and hysterectomy in females.

MATERIAL AND METHODS

One hundred consecutive patients (50 males and 50 females) were studied for the onset of OA and compared for the statistical difference. In females the relationship between onset of OA and menopause and hysterectomy, if done, was noted.

RESULTS

Fifty eight percent of females had onset of symptoms of OA of knees before 50 years of age as compared to only 20% in males (p < 0.05). Sixty four percent of females with OA of knees had the onset of symptoms either perimenopausally or within five years of natural menopause or hysterectomy.

CONCLUSION

There is a definite early peaking of the incidence of OA of knees in women in the fifth decade of life as compared to males. There is an association between OA of knees and menopause and we suggest correlating it with the levels of sex hormones.

Leprosy: a close mimic in a rheumatology clinic

Cutaneous and neurological manifestations of leprosy are readily diagnosed. However, physicians sometimes fail to recognize that leprosy may present with a rheumatic symptoms. A plethora of rheumatic manifestations are associated with leprosy, particularly with lepra reactions. A diligent examination for skin lesions/nerve involvement may uncover the diagnosis of leprosy in a patient referred for a rheumatological disorder. To highlight the fact that leprosy can mimic several rheumatological disorders, we have discussed a few representative cases seen over the past two years at our rheumatology clinic in a teaching hospital. In all these cases, a diagnosis of leprosy was made when the patient was referred for a rheumatic complaint.

von Willebrand's disease with gastrointestinal telangiectasia

A 30-year old woman presented with recurrent and massive bleeding from gastrointestinal tract. Her coagulation profile revealed von Willebrand's disease and her endoscopic examination showed extensive telangiectasia localized to the gastrointestinal tract. The association of Von Willebrand's Disease and telangiectasia is extremely rare and hence the report.