Normal variation in cutaneous blood content and red blood cell velocity in humans

Fully automated dried blood spot sample preparation enables the detection of lower molecular mass peptide and non-peptide doping agents by means of LC-HRMS

The added value of dried blood spot (DBS) samples complementing the information obtained from commonly routine doping control matrices is continuously increasing in sports drug testing. In this project, a robotic-assisted non-destructive hematocrit measurement from dried blood spots by near-infrared spectroscopy followed by a fully automated sample preparation including strong cation exchange solid-phase extraction and evaporation enabled the detection of 46 lower molecular mass (< 2 kDa) peptide and non-peptide drugs and drug candidates by means of LC-HRMS. The target analytes included, amongst others, agonists of the gonadotropin-releasing hormone receptor, the ghrelin receptor, the human growth hormone receptor, and the antidiuretic hormone receptor. Furthermore, several glycine derivatives of growth hormone–releasing peptides (GHRPs), arguably designed to undermine current anti-doping testing approaches, were implemented to the presented detection method. The initial testing assay was validated according to the World Anti-Doping Agency guidelines with estimated LODs between 0.5 and 20 ng/mL. As a proof of concept, authentic post-administration specimens containing GHRP-2 and GHRP-6 were successfully analyzed. Furthermore, DBS obtained from a sampling device operating with microneedles for blood collection from the upper arm were analyzed and the matrix was cross-validated for selected parameters. The introduction of the hematocrit measurement method can be of great value for doping analysis as it allows for quantitative DBS applications by managing the well-recognized “hematocrit effect.”

Breast Edema in Patients Undergoing Breast-Conserving Treatment for Breast Cancer: Assessment via High Frequency Ultrasound

To identify factors that can influence breast edema in women undergoing breast-conserving therapy. Breast edema was assessed clinically and via high frequency ultrasound (HFUS) prior to, during and following radiotherapy. Fifty-four women were assessed. Breast edema was present prior to radiotherapy in patients who had undergone level 2 node dissection or had wound infection after sentinel node dissection. Edema increased during and after radiotherapy and peaked at 4-6 months. The time course of breast edema was related to the extent of nodal dissection, postoperative wound infection and regional radiotherapy. HFUS prior to irradiation was found to be no better than clinical assessment in predicting prolonged parenchymal breast edema but was significantly better at the end of irradiation. Breast edema levels are minimal in patients who do not undergo axillary node dissection or have an uncomplicated sentinel node dissection. Most edema is due to compromise of the draining lymphatics, which relates largely to the extent of axillary node dissection. HFUS appears to be a useful in the research setting in quantifying the effect of techniques that aim to reduce complications such as edema.

Spatial distribution of cutaneous microvasculature and local drug clearance after drug application on the skin

We analysed quantitatively blood microvessels distribution in normal skin. We conclude that the segmental area of blood vessels peaks approximately 0.1 mm below the skin surface, where the upper cutaneous blood plexus resides. Total blood vessels area then decreases quasi-exponentially to a depth of approx. -0.75 mm, with a decay length of approximately 0.1 mm, which is site and skin condition dependent, but at greater depths the decrease is approx. 6-times less steep. The corresponding permeability sink exhibits a similar, but superficially steeper, depth-profile. The lateral localisation of superficial blood vessels is such that ensures maximum diffusion from and into the capillaries, which affects transdermal drug delivery: each hairpin-like loop is in the centre of a papilla that corresponds to a cluster of corneocytes surrounded by main diffusion pathways. The aggregate area of blood vessels in the skin is >or=2.5-fold greater than total organ surface area under normal physiological conditions. The molecules diffusing through the skin barrier are thus largely cleared in outermost 20% of the organ, which may create a drug concentration maximum in the dermis, if clearance increases significantly with time. Skin microdialysis data are therefore extremely sensitive to cutaneous blood flow (distribution) and sampling. Skin microvasculature and its distribution must consequently be considered in all topical or transdermal drug transport studies, for example, by including suitably formulated clearance term into generalised diffusion equation.

Do inflammatory processes contribute to radiation induced erythema observed in the skin of humans?

BACKGROUND

Two prospective trials were designed to determine whether there may be a role for inflammatory mediators in human skin erythema at both high and low doses per fraction and for 'out of field' effects.

METHODS

Trial 1. Effects of topical indomethacin (1%) and hydrocortisone (1%) applied before and during radiotherapy were compared for erythema induced by 20 Gy in four fractions (n = 26, 6 MV). Trial 2. Effects of topical hydrocortisone (1 %) applied before and during radiotherapy and no medication were compared for erythema induced by 1, 3, 5 and 7 Gy in five fractions (n = 21, 120 kV). Erythema was measured using reflectance spectrophotometry (RFS) and laser Doppler (LD) on a weekly basis.

RESULTS

Trial 1. A bi-phasic reaction time course was suggested in two-thirds of the cases. The first phase did not appear to be influenced by hydrocortisone cream but the second was significantly attenuated. Indomethacin had no effect on either reaction phase. Erythema measured several centimetres outside of the field was reduced by hydrocortisone but not by indomethacin. Trial 2. Trial 2 confirmed the presence of measurable erythema, invisible to the eye, that coincided in its time course to the first phase of erythema noted in trial 1. This reaction was more intense than predicted by the LQ formula and was non-significantly attenuated by topical hydrocortisone. RFS readings proved to be less subject to inter- and intra-patient variations than the LD unit used.

CONCLUSION

Inflammatory responses may play a role in the mediation of the erythematous response to radiation in human skin. Further studies are warranted.