Investigation of the Post-Synthetic Confinement of Fluorous Liquids Inside Mesoporous Silica Nanoparticles

Perfluorocarbon (PFC) filled nanoparticles are increasingly being investigated for various biomedical applications. Common approaches for PFC liquid entrapment involve surfactant-based emulsification and Pickering emulsions. Alternatively, PFC liquids are capable of being entrapped inside hollow nanoparticles via a postsynthetic loading method (PSLM). While the methodology for the PSLM is straightforward, the effect each loading parameter has on the PFC entrapment has yet to be investigated. Previous work revealed incomplete filling of the hollow nanoparticles. Changing the loading parameters was expected to influence the ability of the PFC to fill the core of the nanoparticles. Hence, it would be possible to model the loading mechanism and determine the influence each factor has on PFC entrapment by tracking the change in loading yield and efficiency of PFC-filled nanoparticles. Herein, neat PFC liquid was loaded into silica nanoparticles and extracted into aqueous phases while varying the sonication time, concentration of nanoparticles, volume ratio between aqueous and fluorous phases, and pH of the extraction water. Loading yields and efficiency were determined via ¹⁹F nuclear magnetic resonance and N₂ physisorption isotherms. Sonication time was indicated to have the strongest correlation to loading yield and efficiency; however, method validation revealed that the current model does not fully explain the loading capabilities of the PSLM. Confounding variables and more finely controlled parameters need to be considered to better predict the behavior and loading capacity by the PSLM and warrants further study.

Continuous therapeutic ultrasound in the healing process in rat skin

Abstract Introduction : The therapeutic ultrasound is one of the main resources utilized on physical therapy to stimulate the healing due its thermal and mechanic effects. However, your application still not properly standardized. Objective :To analyze the presence of the collagens types I and III stimulated by the ultrasonic wave in continuous mode at the cutaneous injury local for first intention. Material and methods : It was utilized 90 Wistar rats, young adults, with average weight of 230g, divided in 3 groups of 30 animals: control group, treated with ultrasound off; group 1, treated with ultrasound 0.5 W/cm2 and group 2, treated with ultrasound 2.0 W/cm2. Each group was subdivided in 3 subgroups according with the healing phases, 3, 7 and 21 days of consecutive therapeutic sessions. The ultrasound therapy began 24 hours after the termination of the surgical act, at the dorsal region, applying frequency of 3 MHz and intensities 0.5 W/cm2 and 2.0 W/cm2 during 5 minutes under sliding technique. Later, the animals were sacrificed according to the healing phases for removal of incisional area and histological analyses. Conclusions : The results allowed conclude that the continuous mode of therapeutic ultrasound in the intensities 0.5 W/cm2 and 2.0 W/cm2promoted stimulus to formation of collagens types I and III in the lesion area for first intention.

Short-term sensory and cutaneous vascular responses to therapeutic ultrasound in the forearms of healthy volunteers

Background

Therapeutic ultrasound (US) is used for a variety of clinical pathologies and is thought to accelerate tissue repair and help with pain reduction via its thermal and nonthermal effects. The evidence on physiological effects of US on both sensory and vascular functions in humans is incomplete. Hence, the purpose of this study was to determine the short-term impact of two doses of US (3 MHz, 1:4, 0.25 W/cm², 5 min; 1 MHz, continuous, 0.8 W/cm², 3 min), on sensory and vascular responses in the healthy forearms.

Methods

Twenty healthy subjects were recruited (mean age, 29.6 ± 8.8 years) for the study. Superficial blood flow (SBF) in the distal forearms was determined using the tissue viability imaging system. Sensory perception thresholds (SPT) were determined from ring finger (C7, C8) to assess A-beta (at 2,000 Hz) and C fiber function (at 5 Hz), using a Neurometer CPT/C device. Subject’s two hands were randomly allocated to group order (AB/BA). Scores were obtained before and immediately after the application of US and control. Differences in these were analyzed using repeated measures.

Results

Both 3 MHz pulsed US and 1 MHz continuous US showed small to moderate (effect size = 0.12 to 0.68), statistically significant reductions in SBF (3 MHz, mean change = 2.8 AU and 1 MHz, mean change = 3.9 AU, p < 0.05 respectively), skin temperature (2.5°C and 1.1°C, p < 0.05), and SPT at 5 Hz (1.3 and 1 mA, p < 0.05) across time. SPT at 2,000 Hz remained unaltered by all three conditions (p > 0.05). Age and gender also had no effect on all outcome measures (p > 0.05).

Conclusion

This study demonstrated minor reductions in skin blood flow, skin temperatures, and C fiber perception thresholds immediately after 3 MHz, and 1 MHz US. The responses observed may have been due to a thermo-cooling effect of the gel or due to the direct effect of US on C fibers of median and ulnar nerves. US had a negligible effect on A-beta fibres. This would suggest that future studies looking at physiological effects of US should move towards investigating larger dosages and study the effects in patient populations.

Usage Patterns and Beliefs about Therapeutic Ultrasound by Canadian Physical Therapists: An Exploratory Population-Based Cross-Sectional Survey

PURPOSE

To explore the frequency and patterns of ultrasound (US) usage among physical therapists, to describe the most common purposes for using therapeutic US, and to investigate beliefs about therapeutic US.

METHODS

A survey was sent to 95% of physical therapists licensed to practise in the province of Alberta, Canada.

RESULTS

Of 2,269 physical therapists to whom email invitations were sent, 438 (19.3%) provided full responses. RESULTS indicate that US is still frequently incorporated into treatment regimens and is widely believed to be effective; however, the study also found a decrease in US usage over the past 15 years. While physical therapists recognize the lack of evidence for the effectiveness of US, many consider it clinically useful. Physical therapists using US rely largely on their clinical experience when making decisions about its use, but this depends on level of education: clinicians with an MScPT degree tended to base more of their US decisions on research evidence, likely because of the increasing emphasis on research evidence in graduate education.

CONCLUSIONS

Despite the questionable effectiveness of therapeutic US, physical therapists still commonly use this treatment modality, largely because of a belief that US is clinically useful. However, US usage has decreased over the past 15 years.

The efficacy, safety, effectiveness, and cost-effectiveness of ultrasound and shock wave therapies for low back pain: a systematic review

BACKGROUND CONTEXT

Shock wave and especially ultrasound are commonly used to treat low back pain (LBP) in routine practice.

PURPOSE

To assess the evidence on the efficacy, effectiveness, cost-effectiveness, and safety of ultrasound and shock wave to treat LBP.

STUDY DESIGN

Systematic review.

METHODS

An electronic search was performed in MEDLINE, EMBASE, and the Cochrane Library databases up to July 2009 to identify randomized controlled trials (RCTs) comparing vibrotherapy with placebo or with other treatments for LBP. No language restrictions were applied. Additional data were requested from the authors of the original studies. The risk of bias of each study was assessed following the criteria recommended by the Cochrane Back Review Group.

RESULTS

Thirteen studies were identified. The four RCTs complying with the inclusion criteria included 252 patients. Two of the three RCTs on ultrasound had a high risk of bias. For acute patients with LBP and leg pain attributed to disc herniation, ultrasound, traction, and low-power laser obtained similar results. For chronic LBP patients without leg pain, ultrasound was less effective than spinal manipulation, whereas a shock wave device and transcutaneous electrical nerve stimulation led to similar results. Results from the only study comparing ultrasound versus a sham procedure are unreliable because of the inappropriateness of the sham procedure, low sample size, and lack of adjustment for potential confounders. No study assessed cost-effectiveness. No adverse events were reported.

CONCLUSION

The available evidence does not support the effectiveness of ultrasound or shock wave for treating LBP. High-quality RCTs are needed to assess their efficacy versus appropriate sham procedures, and their effectiveness and cost-effectiveness versus other procedures shown to be effective for LBP. In the absence of such evidence, the clinical use of these forms of treatment is not justified and should be discouraged.

A temporal study of ultrasound contrast agent-induced changes in capillary density

OBJECTIVE

The ability of ultrasound (US) and ultrasound contrast agents (UCAs) to induce angiogenesis has been explored as a means of restoring blood flow to ischemic muscle. Because UCAs demonstrate an increasing percentage of collapse cavitation with increasing US pressure (Pr), this study sought to explore the effects of a US Pr that produces 100% collapse cavitation, determine the capillary density changes, and determine the time point of angiogenic rebound in a normal animal model.

METHODS

Using a 1-MHz focused transducer and a peak rarefactional US Pr of 3.8 MPa, rat gracilis muscles were exposed to US, and bioeffects were assessed. Capillary density, as a measure of angiogenesis, was examined. As an additional measure, inflammatory cells were quantified via a color threshold analysis to detect the presence of CD31 and CD34 as a percentage of the total section on stained slides. Six groups (0, 3, 6, 13, 20, and 27 days postexposure [DPE]; n = 3 each) and 5 cage controls were used to characterize the angiogenic response.

RESULTS

Ultrasound-UCA treatment caused the capillary density to decrease acutely (0 DPE) by 70% and inflammatory cells to increase by up to 250%. The angiogenic rebound was observed at 3 DPE but did not return to control levels by 27 DPE, suggesting an incomplete healing response.

CONCLUSIONS

Capillary destruction and inflammation played an important role in the angiogenic response induced by US-UCA. Exposure that causes 100% collapse cavitation causes capillary destruction from which normal rats are unable to recover and suggests a nontherapeutic effect.

Therapeutic ultrasound: the effects upon cutaneous blood flow in humans

The premise of the current crossover, randomised, double-blinded and controlled study was to ascertain the physiologic effects of pulsed and continuous ultrasound (US) upon cutaneous blood flow in humans as measured by laser Doppler flowmetry. Ten healthy volunteers (5 male, 5 female; aged 18 to 36 y) were assigned to undergo four experimental conditions in a predetermined random order: (i) control, (ii) placebo, (iii) pulsed US and (iv) continuous US. US was applied at a frequency of 3 MHz at an intensity of 1 W/cm(2) for a total of 6 min over the lateral aspect of the forearm. Ambient and skin temperatures were measured concomitantly. Statistical analysis indicated that there were significant differences in blood perfusion units between pulsed US and continuous application of US compared with the control condition for cutaneous blood flow at 2 min (p < or = 0.05), 4 min (p < or = 0.03) and 6 min (p < or = 0.05). Additionally, the placebo group was found only significantly to be different from the control condition at 6 min (p = 0.02), indicating that the movement of the transducer head can produce an additional massage effect. There were no significant differences found for ambient or skin temperature recordings. These findings suggest that active US produces significant increases in cutaneous blood flow.

Contraindications for superficial heat and therapeutic ultrasound: do sources agree?11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the author(s) or on any organization with which the author(s) is/are associated

OBJECTIVES

To determine the amount of agreement among general rehabilitation sources for both superficial heating and therapeutic ultrasound contraindications.

DATA SOURCES

English-language textbook and peer-reviewed journal sources, from January 1992 to July 2002. Searches of computerized databases (HealthSTAR, CINAHL, MEDLINE, Embase) as well as Library of Congress Online Catalogs, Books in Print, and AcqWeb's Directory of Publishers and Venders.

DATA SELECTION

Sources were excluded if they (1) were published before 1992, (2) failed to address general rehabilitation audiences, or (3) were identified as a researcher's related publication with similar information on the topic.

DATA EXTRACTION

Type and number of contraindications, type of audience, year of publication, number of references, rationales, and alternative treatment strategies.

DATA SYNTHESIS

Eighteen superficial heat and 20 ultrasound sources identified anywhere from 5 to 22 and 9 to 36 contraindications/precautions, respectively. Agreement among sources was generally high but ranged from 11% to 95%, with lower agreement noted for pregnancy, metal implants, edema, skin integrity, and cognitive/communicative concerns. Seventy-two percent of superficial heat sources and 25% of ultrasound sources failed to reference at least 1 contraindication claim.

CONCLUSIONS

Agreement among contraindication sources was generally good for both superficial heat and therapeutic ultrasound. Sources varied with regard to the number of contraindications, references, and rationales cited. Greater reliance on objective data and standardized classification systems may serve to develop more uniform guidelines for superficial heat and therapeutic ultrasound.

Continuous and pulsed ultrasound do not increase heat shock protein 72 content

Therapeutic ultrasound (US) is a common treatment used in the rehabilitation of injured muscle. To determine whether therapeutic US could increase the content of heat shock protein (HSP) 72 in skeletal muscle, male Sprague-Dawley rats were anesthetized and the muscles from one hind limb treated with 15 min of US at 1 MHz using either: 1. continuous US at 1.0 W/cm(2), 2. pulsed US at 2.0 W/cm(2) at 50% duty cycle, or 3. pulsed US at 1.0 W/cm(2) at 20% duty cycle. All treatments were applied using a transducer (1.6-cm diameter) on an area of the rat hind limb twice the size of the sound head. At 24 h following treatment, the plantaris, soleus, white and red gastrocnemius muscles were removed and assessed for HSP 72 content by Western blotting. No significant increases in HSP 72 content were detected in any of the muscles examined following any US treatment. These results suggest muscle HSP content is not elevated following a typical therapeutic dose of either continuous or pulsed US in the rat.

The role of electrotherapy in contemporary physiotherapy practice

Although electrotherapy has a well established role within physiotherapy practice, the current concepts that influence its application vary considerably from those proposed historically. It is argued that there is a place for electrophysical modalities in contemporary practice, and several basic principles are considered together with more specific information regarding two modalities namely, ultrasound and interferential therapy. Electrophysical agents are utilised to bring about physiological effects, and it is these changes which bring about the therapeutic benefit rather than the modality itself. Clinical decision protocols employing the available evidence should enable the most appropriate modality to be employed for a particular patient. Indiscriminate use of electrotherapy is unlikely to yield significant benefit, however used at the right time, it has the potential to achieve beneficial effect. The patient management programme which combines manual therapy, exercise therapy and electrotherapy, based on current evidence, should enable the most efficacious management of a patients' dysfunction. This paper aims to consider some of the current concepts in electrotherapy and to relate this to both general and specific treatments.