Does the technique employed for skin temperature assessment alter outcomes? A systematic review

Skin temperature is an important physiological measure that can reflect the presence of illness and injury as well as provide insight into the localised interactions between the body and the environment. The aim of this systematic review was to analyse the agreement between conductive and infrared means of assessing skin temperature which are commonly employed in in clinical, occupational, sports medicine, public health and research settings. Full-text eligibility was determined independently by two reviewers. Studies meeting the following criteria were included in the review: 1) the literature was written in English, 2) participants were human (in vivo), 3) skin surface temperature was assessed at the same site, 4) with at least two commercially available devices employed—one conductive and one infrared—and 5) had skin temperature data reported in the study. A computerised search of four electronic databases, using a combination of 21 keywords, and citation tracking was performed in January 2015. A total of 8,602 were returned. Methodology quality was assessed by 2 authors independently, using the Cochrane risk of bias tool. A total of 16 articles (n = 245) met the inclusion criteria. Devices are classified to be in agreement if they met the clinically meaningful recommendations of mean differences within ±0.5 °C and limits of agreement of ±1.0 °C. Twelve of the included studies found mean differences greater than ±0.5 °C between conductive and infrared devices. In the presence of external stimulus (e.g. exercise and/or heat) five studies foundexacerbated measurement differences between conductive and infrared devices. This is the first review that has attempted to investigate presence of any systemic bias between infrared and conductive measures by collectively evaluating the current evidence base. There was also a consistently high risk of bias across the studies, in terms of sample size, random sequence generation, allocation concealment, blinding and incomplete outcome data. This systematic review questions the suitability of using infrared cameras in stable, resting, laboratory conditions. Furthermore, both infrared cameras and thermometers in the presence of sweat and environmental heat demonstrate poor agreement when compared to conductive devices. These findings have implications for clinical, occupational, public health, sports science and research fields.

Early harvest and ensilage of forage sorghum infected with ergot (Claviceps africana) reduces the risk of livestock poisoning.

Sorghum ergot produces dihydroergosine (DHES) and related alkaloids, which cause hyperthermia in cattle. Proportions of infected panicles (grain heads), leaves and stems were determined in two forage sorghum crops extensively infected 2 to 4 weeks prior to sampling and the panicles were assayed for DHES. Composite samples from each crop, plus a third grain variety crop, were coarsely chopped and half of each sealed in plastic buckets for 6 weeks to simulate ensilation. The worst-infected panicles contained up to 55 mg DHES/kg, but dilution reduced average concentrations of DHES in crops to approximately 1 mg/kg, a relatively safe level for cattle. Ensilation significantly (P = 0.043) reduced mean DHES concentrations from 0.85 to 0.46 mg/kg.

Effect of sorghum ergot (Claviceps africana) on the performance of steers (Bos taurus) in a feedlot.

The effect of ergot (Claviceps africana) in naturally infected sorghum was assessed in feedlot rations. Thirty-two Hereford steers (Bos taurus) in individual pens with access to shade were adapted to feedlot conditions and then offered one of four rations containing 0, 4.4, 8.8 or 17.6 mg/kg of ergot alkaloids (84% dihydroergosine, 10% dihydroelymoclavine and 6% festuclavine), equivalent to ~0, 10, 20 or 40 g/kg ergot (sclerotia/sphacelia) in the rations. These rations were withdrawn at noon on the second day because of severe hyperthermia and almost complete feed refusal in ergot-fed steers. After recovery on ergot-free rations for 5 days, treatment groups were incrementally introduced, over a further 3–12 days, to rations containing 0, 1.1, 2.2 or 4.4 mg/kg of alkaloids (~0, 2.5, 5 or 10 g/kg ergot, respectively). Relative exposure to ergot was maintained, so that the zero- (control), low-, medium- and high-ergot groups remained so. Steers were individually fed ad libitum, and water was freely available. Steers in all ergot-fed groups had significantly elevated rectal temperatures at 0800–1000 hours, even when the temperature–humidity index was only moderate (~70), and displayed other signs of hyperthermia (increased respiration rate, mouth breathing, excessive salivation and urination), as the temperature–humidity index increased to 73–79 during the day. Plasma prolactin was significantly reduced in ergot-fed groups. Voluntary feed intakes (liveweight basis) of the ergot-fed groups were significantly reduced, averaging 94, 86 and 86%, respectively, of the feed intakes of the control group. Hair coats were rough. While the control steers grew from a mean initial liveweight of 275 kg to a suitable slaughter weight of 455 kg in 17 weeks (growth rate 1.45 kg/day), ergot-fed groups gained only 0.77–1.10 kg/day and took at least 5 weeks longer to reach the slaughter weight, despite removal of ergot at the same time as control steers were sent to slaughter. Sorghum ergot, even at low concentrations (1.1 mg alkaloids/kg feed) is severely detrimental to the performance of steers in the feedlot.

Platinum dendritic nanoparticles with magnetic behavior

Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ∼4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

Size Control and Magnetic Property Trends in Cobalt Ferrite Nanoparticles Synthesized Using an Aqueous Chemical Route

Cobalt ferrite (CoFe2O4) is an engineering material which is used for applications such as magnetic cores, magnetic switches, hyperthermia based tumor treatment, and as contrast agents for magnetic resonance imaging. Utility of ferrites nanoparticles hinges on its size, dispersibility in solutions, and synthetic control over its coercivity. In this work, we establish correlations between room temperature co-precipitation conditions, and these crucial materials parameters. Furthermore, post-synthesis annealing conditions are correlated with morphology, changes in crystal structure and magnetic properties. We disclose the synthesis and process conditions helpful in obtaining easily sinterable CoFe2O4 nanoparticles with coercive magnetic flux density (H-c) in the range 5.5-31.9 kA/m and M-s in the range 47.9-84.9 A.m(2)Kg(-1). At a grain size of similar to 54 +/- 2 nm (corresponding to 1073 K sintering temperature), multi-domain behavior sets in, which is indicated by a decrease in H-c. In addition, we observe an increase in lattice constant with respect to grain size, which is the inverse of what is expected of in ferrites. Our results suggest that oxygen deficiency plays a crucial role in explaining this inverse trend. We expect the method disclosed here to be a viable and scalable alternative to thermal decomposition based CoFe2O4 synthesis. The magnetic trends reported will aid in the optimization of functional CoFe2O4 nanoparticles

Avaliação do efeito do chá verde sobre a pressão arterial, função endotelial, perfil metabólico, atividade inflamatória e adiposidade corporal em mulheres pré-hipertensas obesas

As doenças cardiovasculares são a principal causa de morte nos países ocidentais. Alguns estudos sugerem que o chá verde tem efeito benéfico sobre diferentes fatores de risco cardiovascular. No entanto, outros estudos não mostraram essa associação. Objetiva avaliar em mulheres pré-hipertensas obesas o efeito do consumo de chá verde sobre: a pressão arterial, a função endotelial, o perfil metabólico, a atividade inflamatória e a adiposidade corporal. Estudos clínico, randomizado, cruzado, duplo-cego e placebo-controlado. Durante 4 semanas as mulheres foram orientadas a ingerir 3 cápsulas de extrato de chá verde por dia (500mg extrato chá verde/cápsula) passando por 2 semanas de washout e posteriormente ingeriam por mais 4 semanas o placebo. As mulheres que iniciaram o estudo tomando placebo posteriormente utilizaram o chá verde. Ou seja, todas as pacientes receberam chá verde e placebo por um mesmo período. No início e final de cada tratamento foram analisadas as variáveis. Foram avaliadas 20 mulheres pré-hipertensas, obesidade grau I e II, idade entre 25 e 59 anos. O local do estudo foi o Laboratório da Disciplina de Fisiopatologia Clínica e Experimental Clinex. Universidade do Estado do Rio de Janeiro. As variáveis estudadas foram a pressão arterial, índice de hipertemia reativa (avaliada com Endo-PAT2000), proteína C reativa, interleucina-6, fator de necrose tumoral-α, molécula de adesão intercelular e molécula de adesão vascular celular, inibidor de ativador do plasminogênio, fator de crescimento endotelial vascular, E-selectina, adiponectina, colesterol total, LDL-colesterol, HDL-colesterol, triglicérides, glicemia, insulina, HOMA, índice de massa corporal, circunferência de cintura, circunferência de quadril, relação cintura quadril e percentual de gordura corporal. Como resultados, na avaliação da pressão arterial pela monitorização ambulatorial da pressão arterial, observou-se redução significativa da pressão arterial sistólica de 24 horas (pré 130,31,7 mmHg vs. pós 127,02,0 mmHg; p= 0,02), pressão arterial sistólica diurna (pré 134,01,7 mmHg vs. pós 130,72,0 mmHg; p= 0,04) e pressão arterial sistólica noturna (pré 122,21,8 mmHg vs. pós 118,42,2 mmHg; p= 0,02), após o consumo do chá verde, em comparação ao uso do placebo. Após o consumo do chá verde foi observado aumento, embora estatisticamente não significativo, no índice de hiperemia reativa (pré 1,980,10 vs. pós 2,220,14), além de redução expressiva na concentração da molécula de adesão intercelular (pré 91,88,0 ng/ml vs. pós 85,85,6 ng/ml) e do fator de crescimento endotelial vascular (pré 195,846,2 pg/ml vs. pós 158,638,7 pg/ml), porém sem significância estatística. As demais variáveis avaliadas não se modificaram de forma significativa após o consumo do chá verde, em comparação ao placebo. Foi observada forte correlação entre redução de pressão arterial sistólica e diastólica de 24hs, avaliada pela monitorização ambulatorial da pressão arterial, e o aumento do índice de hipertemia reativa (r= -0,47; r= -0,50, respectivamente). Os resultados do presente estudo sugerem que o chá verde tem efeito benéfico sobre a pressão arterial e possivelmente sobre a função endotelial.

纳米水基磁性液体在肿瘤治疗领域的研究进展

结合作者在纳米磁性液体方面的研究经历，介绍了生物医学应用领域纳米磁性粒子的组成结构及特点，指出高分子改性纳米磁性粒子具有生物相容性好、稳定性强、载药量高的优点，并对目前高分子改性纳米四氧化三铁颗粒的制备方法及特点进行了对比分析。指出进一步研制磁响应性强、载药量高、粒度分布均匀的纳米磁性粒子，使之对癌细胞具有亲和作用，尽量避免对毛细血管网状内皮系统的清除，是未来肿瘤治疗领域纳米磁性粒子的研发目标，并对目前制备方法中存在的不足提出了改进的建议。

INVESTIGATION OF BUBBLE DYNAMICS AND HEATING DURING FOCUSED ULTRASOUND INSONATION IN TISSUE-MIMICKING MATERIALS

The deposition of ultrasonic energy in tissue can cause tissue damage due to local heating. For pressures above a critical threshold, cavitation will occur in tissue and bubbles will be created. These oscillating bubbles can induce a much larger thermal energy deposition in the local region. Traditionally, clinicians and researchers have not exploited this bubble-enhanced heating since cavitation behavior is erratic and very difficult to control. The present work is an attempt to control and utilize this bubble-enhanced heating. First, by applying appropriate bubble dynamic models, limits on the asymptotic bubble size distribution are obtained for different driving pressures at 1 MHz. The size distributions are bounded by two thresholds: the bubble shape instability threshold and the rectified diffusion threshold. The growth rate of bubbles in this region is also given, and the resulting time evolution of the heating in a given insonation scenario is modeled. In addition, some experimental results have been obtained to investigate the bubble-enhanced heating in an agar and graphite based tissue- mimicking material. Heating as a function of dissolved gas concentrations in the tissue phantom is investigated. Bubble-based contrast agents are introduced to investigate the effect on the bubble-enhanced heating, and to control the initial bubble size distribution. The mechanisms of cavitation-related bubble heating are investigated, and a heating model is established using our understanding of the bubble dynamics. By fitting appropriate bubble densities in the ultrasound field, the peak temperature changes are simulated. The results for required bubble density are given. Finally, a simple bubbly liquid model is presented to estimate the shielding effects which may be important even for low void fraction during high intensity focused ultrasound (HIFU) treatment.

THE ROLE OF ACOUSTIC CAVITATION IN ENHANCED ULTRASOUND-INDUCED HEATING IN A TISSUE-MIMICKING PHANTOM

A complete understanding of high-intensity focused ultrasound-induced temperature changes in tissue requires insight into all potential mechanisms for heat deposition. Applications of therapeutic ultrasound often utilize acoustic pressures capable of producing cavitation activity. Recognizing the ability of bubbles to transfer acoustic energy into heat generation, a study of the role bubbles play in tissue hyperthermia becomes necessary. These bubbles are typically less than 50μm. This dissertation examines the contribution of bubbles and their motion to an enhanced heating effect observed in a tissue-mimicking phantom. A series of experiments established a relationship between bubble activity and an enhanced temperature rise in the phantom by simultaneously measuring both the temperature change and acoustic emissions from bubbles. It was found that a strong correlation exists between the onset of the enhanced heating effect and observable cavitation activity. In addition, the likelihood of observing the enhanced heating effect was largely unaffected by the insonation duration for all but the shortest of insonation times, 0.1 seconds. Numerical simulations were used investigate the relative importance of two candidate mechanisms for heat deposition from bubbles as a means to quantify the number of bubbles required to produce the enhanced temperature rise. The energy deposition from viscous dissipation and the absorption of radiated sound from bubbles were considered as a function of the bubble size and the viscosity of the surrounding medium. Although both mechanisms were capable of producing the level of energy required for the enhanced heating effect, it was found that inertial cavitation, associated with high acoustic radiation and low viscous dissipation, coincided with the the nature of the cavitation best detected by the experimental system. The number of bubbles required to account for the enhanced heating effect was determined through the numerical study to be on the order of 150 or less.

Quantitative Particle Characterization by Scattered Ultrasound

The topic of this thesis is an acoustic scattering technique for detennining the compressibility and density of individual particles. The particles, which have diameters on the order of 10 µm, are modeled as fluid spheres. Ultrasonic tone bursts of 2 µsec duration and 30 MHz center frequency scatter from individual particles as they traverse the focal region of two confocally positioned transducers. One transducer acts as a receiver while the other both transmits and receives acoustic signals. The resulting scattered bursts are detected at 90° and at 180° (backscattered). Using either the long wavelength (Rayleigh) or the weak scatterer (Born) approximations, it is possible to detennine the compressibility and density of the particle provided we possess a priori knowledge of the particle size and the host properties. The detected scattered signals are digitized and stored in computer memory. With this information we can compute the mean compressibility and density averaged over a population of particles ( typically 1000 particles) or display histograms of scattered amplitude statistics. An experiment was run first run to assess the feasibility of using polystyrene polymer microspheres to calibrate the instrument. A second study was performed on the buffy coat harvested from whole human blood. Finally, chinese hamster ovary cells which were subject to hyperthermia treatment were studied in order to see if the instrument could detect heat induced membrane blebbing.

Acoustic radiation force impulse imaging (ARFI) on an IVUS circular array.

Our long-term goal is the detection and characterization of vulnerable plaque in the coronary arteries of the heart using intravascular ultrasound (IVUS) catheters. Vulnerable plaque, characterized by a thin fibrous cap and a soft, lipid-rich necrotic core is a precursor to heart attack and stroke. Early detection of such plaques may potentially alter the course of treatment of the patient to prevent ischemic events. We have previously described the characterization of carotid plaques using external linear arrays operating at 9 MHz. In addition, we previously modified circular array IVUS catheters by short-circuiting several neighboring elements to produce fixed beamwidths for intravascular hyperthermia applications. In this paper, we modified Volcano Visions 8.2 French, 9 MHz catheters and Volcano Platinum 3.5 French, 20 MHz catheters by short-circuiting portions of the array for acoustic radiation force impulse imaging (ARFI) applications. The catheters had an effective transmit aperture size of 2 mm and 1.5 mm, respectively. The catheters were connected to a Verasonics scanner and driven with pushing pulses of 180 V p-p to acquire ARFI data from a soft gel phantom with a Young's modulus of 2.9 kPa. The dynamic response of the tissue-mimicking material demonstrates a typical ARFI motion of 1 to 2 microns as the gel phantom displaces away and recovers back to its normal position. The hardware modifications applied to our IVUS catheters mimic potential beamforming modifications that could be implemented on IVUS scanners. Our results demonstrate that the generation of radiation force from IVUS catheters and the development of intravascular ARFI may be feasible.

A Plasmonic Gold Nanostar Theranostic Probe for In Vivo Tumor Imaging and Photothermal Therapy.

Nanomedicine has attracted increasing attention in recent years, because it offers great promise to provide personalized diagnostics and therapy with improved treatment efficacy and specificity. In this study, we developed a gold nanostar (GNS) probe for multi-modality theranostics including surface-enhanced Raman scattering (SERS) detection, x-ray computed tomography (CT), two-photon luminescence (TPL) imaging, and photothermal therapy (PTT). We performed radiolabeling, as well as CT and optical imaging, to investigate the GNS probe's biodistribution and intratumoral uptake at both macroscopic and microscopic scales. We also characterized the performance of the GNS nanoprobe for in vitro photothermal heating and in vivo photothermal ablation of primary sarcomas in mice. The results showed that 30-nm GNS have higher tumor uptake, as well as deeper penetration into tumor interstitial space compared to 60-nm GNS. In addition, we found that a higher injection dose of GNS can increase the percentage of tumor uptake. We also demonstrated the GNS probe's superior photothermal conversion efficiency with a highly concentrated heating effect due to a tip-enhanced plasmonic effect. In vivo photothermal therapy with a near-infrared (NIR) laser under the maximum permissible exposure (MPE) led to ablation of aggressive tumors containing GNS, but had no effect in the absence of GNS. This multifunctional GNS probe has the potential to be used for in vivo biosensing, preoperative CT imaging, intraoperative detection with optical methods (SERS and TPL), as well as image-guided photothermal therapy.

Incorporation of multiwalled carbon nanotubes to acrylic based bone cements: Effects on mechanical and thermal properties

Polymethyl methacrylate (PMMA) bone cement–multiwalled carbon nanotube (MWCNT) nanocomposites with a weight loading of 0.1% were prepared using 3 different methods of MWCNT incorporation. The mechanical and thermal properties of the resultant nanocomposite cements were characterised in accordance with the international standard for acrylic resin cements. The mechanical properties of the resultant nanocomposite cements were influenced by the type of MWCNT and method of incorporation used. The exothermic polymerisation reaction for the PMMA bone cement was significantly reduced when thermally conductive functionalised MWCNTs were added. This reduction in exotherm translated in a decrease in thermal necrosis index value of the respective nanocomposite cements, which potentially could reduce the hyperthermia experienced in vivo. The morphology and degree of dispersion of the MWCNTs in the PMMA matrix at different scales were analysed using scanning electron microscopy. Improvements in mechanical properties were attributed to the MWCNTs arresting/retarding crack propagation through the cement by providing a bridging effect into the wake of the crack, normal to the direction of crack growth. MWCNT agglomerations were evident within the cement microstructure, the degree of these agglomerations was dependent on the method used to incorporate the MWCNTs into the cement.

AC magnetic heating of superparamagnetic Fe and Co nanoparticles

AC magnetic heating of superparamagnetic Co and Fe nanoparticles for application in hyperthermia was measured to find a size of nanoparticles that would result in an optimal heating for given amplitude and frequency of ac externally applied magnetic field. To measure it, a custom-made power supply connected to a 20-turn insulated copper coil in the shape of a spiral solenoid cooled with water was used. A fiber-optic temperature sensor has been used to measure the temperature with an accuracy of 0.0001 K. The magnetic field with magnitude of 20.6 µT and a frequency of oscillation equal to 348 kHz was generated inside the coil to heat magnetic nanoparticles. The maximum specific power loss or the highest heating rate for Co magnetic nanoparticles was achieved for nanoparticles of 8.2 nm in diameter. The maximum heating rate for coated Fe was found for nanoparticles with diameter of 18.61 nm. © (2013) Trans Tech Publications, Switzerland.

Resonantly loaded apertures for high-resolution near field surface imaging

A novel type of microwave probes based on the loaded aperture geometry has been proposed and experimentally evaluated for dielectrics characterisation and high-resolution near-field imaging. Experimental results demonstrate the possibility of very accurate microwave spectroscopic characterisation of thin lossy dielectric samples and biological materials containing water. High-resolution images of the subwavelength lossy dielectric strips and wet and dry leaves have been obtained with amplitude contrast around 10-20 dB and spatial resolution better than one-tenth of a wavelength in the near-field zone. A microwave imaging scenario for the early-stage skin cancer identification based on the artificial dielectric model has also been explored. This model study shows that the typical resolution of an artificial malignant tumour with a characteristic size of one-tenth of a wavelength can be discriminated with at least 6 dB amplitude and 50° phase contrast from the artificial healthy skin and with more than 3 dB contrast from a benign lesion of the same size. It has also been demonstrated that the proposed device can efficiently deliver microwave energy to very small, subwavelength, focal areas which is highly sought in the microwave hyperthermia applications.