Castrati singers: surgery for religion and art

The act of castration was practiced from ancient times. In countries of Middle and Far East, castration was often done to provide eunuchs as guardians of the harems. In Europe and especially in Italy, it was carried out to preserve the male voice unbroken into adult life. From 16th century till the end of 18th century, castrati singers dominated opera with their supernatural voices. Boys were castrated mainly before the age of 9 years and when they grew up they had feminine characteristics, such as smooth, hairless bodies, breasts, infantile penis. The training procedure to become a castrato singer was very intense and lasted up to ten years. The most common surgical technique was either to sever the spermatic cords or crush the testis with the fingers. The voice of a castrato was the outcome of a larynx the size of a child’s combined with the lung volume of an adult male. The castrati singers became superstars who dominated opera, singing both male and female roles for more than 200 years. Castrated for art, the beauty, range and flexibility of their voices raised them to mythical status

Overcoming the blood–brain barrier: the role of nanomaterials in treating neurological diseases

Therapies directed toward the central nervous system remain difficult to translate into improved clinical outcomes. This is largely due to the blood–brain barrier (BBB), arguably the most tightly regulated interface in the human body, which routinely excludes most therapeutics. Advances in the engineering of nanomaterials and their application in biomedicine (i.e., nanomedicine) are enabling new strategies that have the potential to help improve our understanding and treatment of neurological diseases. Herein, the various mechanisms by which therapeutics can be delivered to the brain are examined and key challenges facing translation of this research from benchtop to bedside are highlighted. Following a contextual overview of the BBB anatomy and physiology in both healthy and diseased states, relevant therapeutic strategies for bypassing and crossing the BBB are discussed. The focus here is especially on nanomaterial‐based drug delivery systems and the potential of these to overcome the biological challenges imposed by the BBB. Finally, disease‐targeting strategies and clearance mechanisms are explored. The objective is to provide the diverse range of researchers active in the field (e.g., material scientists, chemists, engineers, neuroscientists, and clinicians) with an easily accessible guide to the key opportunities and challenges currently facing the nanomaterial‐mediated treatment of neurological diseases

A velocity profile equation for blood flow in small arterioles and venules of small mammals in vivo and an evaluation based on literature data

An empirical parametric equation with 2 bluntness parameters was introduced for describing the velocity profile of blood in the small arterioles and venules of small mammals, in vivo, with the basic approximations of the axisymmetric flow in cylindrical geometry, zero velocity at the wall and a blunter than parabolic flow profile. The purpose was to evaluate the usefulness of this equation in describing the velocity profile and in estimating the volume flow when only one velocity measurement is available near the vessel axis. The equation was tested on 17 velocity profiles (9 arteriolar and 8 venular) previously measured by particle image velocimetry (PIV) techniques, at diameters ranging from 17 to 38.6 mu m. The correlation coefficients of each experimental profile were higher than 0.96. The average relative error-bias measured at 10 radial segments ranged between -5% to 1%, leading to an average relative volume flow estimation error for all the 17 velocity profiles of -1.8% with a standard deviation of 4.3%

Blood flow velocity comparison in the eye capillaries and postcapillary venules between normal pregnant and non-pregnant women

Background: There is no consensus on how much and at what diameters the blood flow velocity changes in the female microcirculation during normal pregnancy. Methods: A non-contact, digital slit-lamp biomicroscopy system was used to measure axial blood velocity (Vax) and diameter (D) in the conjunctival microcirculation of 28 normal non-pregnant women (Control Group), 17 women in the first semester of their normal pregnancy (Group 1) and 16 women in the third trimester of their normal pregnancy (Group 2). Blood volume flow (Q) was estimated from Vax and D. Microvessels were classified as “capillaries” (CAP) with D < 9 μm, “postcapillary venules of size 1” (PC1) with 9 ≤ D < 14 μm and “postcapillary venules of size 2” (PC2) with 14 ≤ D ≤ 24 μm. Results: The women groups did not differ significantly in age, diastolic and systolic pressure and diameter of each size. Taking as baseline the capillary Vax of 0.51 mm/s of the Control Group, there was a statistically significant (p < 0.001) increase to 0.74 mm/s (45%) in Group 1 and to 0.95 mm/s (86%) in Group 2. This significant Vax increase in capillaries (CAP) was a consistent finding irrespective of the exact vessel size cut-off value for discriminating CAP from PC1. There was no statistical difference in Vax among groups at postcapillary venules of size 2 (PC2). Statistical conclusions for blood volume flows were similar to velocities. Conclusions: Normal pregnancy increases significantly axial blood velocity (Vax) in capillaries (CAP) with diameter <9 μm. © 2019 Elsevier Inc