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Viscoelastic properties of a virucidal cream containing the monoglyceride monocaprin: Effects of formulation variables: A technical note

admin — Mon, 02 Feb 2009 13:02:00 +0000

Conclusions The viscoelastic properties of the cream formulations were tested by 2 methods (ie, increased stress; increased frequency tests). The rheology experiments indicate that the formulations are stable; they show resistance to external forces, as their elastic properties are sustained whether or not the magnitude or frequency of external forces are increased. The results show that rheological properties of the formulations are affected by the proportion of the oil phase; the amount of carbomer in the aqueous phase, but the effect of monocaprin is modest. Increasing carbomer amount increases viscosity; elasticity. Increasing the oil volume fraction increased the structural stability of the creams. The formulation containing monocaprin, which yielded the most viscoelastic structure was a cream containing 10% oil phase; 0.5% carbomer (Formulation 9).

Th�runn �sk Thorgeirsd�ttir1Email:tthorgeirsdottir@actavis.com?Halld�r Thormar2?Th�rd�s Kristmundsd�ttir1
[1] Faculty of Pharmacy, University of Iceland, Hagi, Hofsvallagtu 53, 107 Reykjav�k, Iceland ;[2] Institute of Biology, University of Iceland, IS-107 Reykjavik, Iceland

Value of repeated fine needle aspiration cytology in patients with nodular goiter.

admin — Wed, 02 Apr 2008 02:56:14 +0000

OBJECTIVE: To assess the value of reaspiration cytology in benign nodular thyroid disease. DESIGN: We prospectively studied 400 patients (365 women, 35 men) aged 46 years (18-89) with nodular thyroid disease and initial benign fine needle aspiration cytology (FNAC). Reaspiration of the same nodule was performed in a median follow-up time of 14 months (6-18). RESULTS: Repeat FNAC was benign in 346 patients (86.5%), insufficient for diagnosis in 42 (10.5%), suspicious in 16 (2.5%) and malignant in 2 (0.5%). All diagnostic changes to suspicious malignant cytology took place in patients with solitary nodules. Surgery confirmed thyroid cancer in the 2 patients with malignant cytology, in 5 of 10 patients with suspicious cytology and in none of 39 patients with benign cytology who underwent surgery for other reasons. Clinical changes (size increase or local symptoms) were not related to changes in cytologic diagnosis after a second aspiration, nor with the results of the biopsy. CONCLUSION: Repeat aspirationcytology of thyroid nodules may correct initial false negative results because of cytologic misdiagnosis, occurring in 1.75% of patients, whereas clinical changes did not contribute to diagnosis change. Repeat aspiration cytology is recommended in all patients with nodular goiter.

Menendez-Torre,E　Pineda-Arribas,J　Martinez-de-Esteban,JP　Lopez-Carballo,MT　de-Miguel,C　Salvador,P
Unidad de Patologia Tiroidea, Hospital de Navarra y Hospital Virgen del Camino, Servicio Navarro de Salud, Pamplona, Spain.

Adolescent　 Adult　 Aged　 Aged, 80 and over Biopsy, Fine-Needle Female

Viscoelastic properties of human tympanic membrane.

admin — Wed, 12 Mar 2008 01:58:33 +0000

Cheng,T; Dai,C; Gan,RZ

Abstract The tympanic membrane or eardrum of human ear transfers sound waves intomechanical vibration from the external ear canal into the middle ear and cochlea. Mechanicalproperties of the tympanic membrane (TM) play an important role in sound transmission through theear. Although limited resources about linear elastic properties of the TM are available inliterature, there is a lack of measurement or modeling of viscoelastic properties of the TM at lowstress levels. In this study, the uniaxial tensile, stress relaxation, and failure tests wereconducted on fresh human cadaver TM specimens to explore mechanical properties of the TM. Theexperimental results were analyzed using the hyperelastic Ogden model and digital image correlationmethod. The constitutive equation and non-linear elastic properties of the TM were presented byfunctions of the stress and strain at the stress range from 0 to 1 MPa. Viscoelastic properties ofthe TM were described by the stress relaxation function and hysteresis. The results show that theuniaxial tensile test with the aid of digital image correlation analysis is a reliable and usefulapproach for measuring mechanical properties of ear tissues. The data presented in this papercontribute to ear biomechanics in both experimental measurement and theoretical analysis of eartissues.

Keywords Models, Biological; Tympanic Membrane

Annals of Biomedical Engineering
0090-6964, Volume 35, Issue 2, 2007, Pages 3-314

Vertebral osteoporosis and trabecular bone quality

admin — Wed, 12 Mar 2008 01:47:37 +0000

McDonnell,P; McHugh,PE; O”Mahoney,D

Abstract Vertebral fractures due to osteoporosis commonly occur under non-traumaticloading conditions. This problem affects more than 1 in 3 women and 1 in 10 men over a lifetime.Measurement of bone mineral density (BMD) has traditionally been used as a method for diagnosis ofvertebral osteoporosis. However, this method does not fully account for the influence of changes inthe trabecular bone quality, such as micro-architecture, tissue properties and levels ofmicrodamage, on the strength of the vertebra. Studies have shown that deterioration of the vertebraltrabecular architecture results in a more anisotropic structure which has a greater susceptibilityto fracture. Transverse trabeculae are preferentially thinned and perforated while the remainingvertical trabeculae maintain their thickness. Such a structure is likely to be more susceptible tobuckling under normal compression loads and has a decreased ability to withstand unusual or off-axisloads. Changes in tissue material mechanical properties and levels of microdamage due toosteoporosis may also compromise the fracture resistance of vertebral trabecular bone. Newdiagnostic techniques are required which will account for the influence of these changes in bonequality. This paper reviews the influence of the trabecular architecture, tissue properties andmicrodamage on fracture risk for vertebral osteoporosis. The morphological characteristics of normaland osteoporotic architectures are compared and their potential influence on the strength of thevertebra is examined. The limitations of current diagnostic methods for osteoporosis are identifiedand areas for future research are outlined.

Keywords Bone Density; Densitometry; Osteoporosis; Spinal Fractures; Spine

Annals of Biomedical Engineering
0090-6964, Volume 35, Issue 2, 2007, Pages 3-189

Vasoactivity of blood vessels using a novel isovolumic myograph

admin — Wed, 12 Mar 2008 01:28:23 +0000

Lu,X; Kassab,GS

Abstract The vasoactivity of blood vessel is impaired by cardiovascular disease. Theex-vivo measurements of vasoactivity (wire and pressure myographs) have some inherent difficultiesin the characterization of pharmacodynamics and biomechanics. Here, we introduce a novel isovolumicmyograph which allows simultaneous measurement of both dynamic pressure and dimensional changesduring vasoconstriction or vasodilation. The principle of the isovolumic myograph is based on theutility of a hydraulically closed system with low compliance such that contraction against anincompressible fluid increases the pressure with the closed system while dilation decreases it. Wedemonstrate the sensitivity and utility of the new technique by the response of elastic (carotid),muscular (femoral) arteries, and femoral veins. The results show characteristic dynamic pressureresponse for each vessel type. Furthermore, our results show a Hill-type equation for thetension-velocity relation for smooth muscles as well as characteristic curves for each contraction.These novel findings for blood vessels will advance our knowledge of endothelium and vascular smoothmuscle mechanics and pharmacodynamics.

Keywords Blood Vessels; Vasoconstriction; Vasodilation

Annals of Biomedical Engineering
0090-6964, Volume 35, Issue 3, 2007, Pages 3-366