Effect of low-intensity focused ultrasound on the middle ear in a mouse model of acute otitis media

Advancements in transdermal drug delivery: A comprehensive review of physical penetration enhancement techniques

Transdermal drug administration has grown in popularity in the pharmaceutical research community due to its potential to improve drug bioavailability, compliance among patients, and therapeutic effectiveness. To overcome the substantial barrier posed by the stratum corneum (SC) and promote drug absorption within the skin, various physical penetration augmentation approaches have been devised. This review article delves into popular physical penetration augmentation techniques, which include sonophoresis, iontophoresis, magnetophoresis, thermophoresis, needle-free injection, and microneedles (MNs) Sonophoresis is a technique that uses low-frequency ultrasonic waves to break the skin's barrier characteristics, therefore improving drug transport and distribution. In contrast, iontophoresis uses an applied electric current to push charged molecules of drugs inside the skin, effectively enhancing medication absorption. Magnetophoresis uses magnetic fields to drive drug carriers into the dermis, a technology that has shown promise in aiding targeted medication delivery. Thermophoresis is the regulated heating of the skin in order to improve drug absorption, particularly with thermally sensitive drug carriers. Needle-free injection technologies, such as jet injectors (JIs) and microprojection arrays, offer another option by producing temporary small pore sizes in the skin, facilitating painless and effective drug delivery. MNs are a painless, minimally invasive method, easy to self-administration, as well as high drug bioavailability. This study focuses on the underlying processes, current breakthroughs, and limitations connected with all of these approaches, with an emphasis on their applicability in diverse therapeutic areas. Finally, a thorough knowledge of these physical enhancement approaches and their incorporation into pharmaceutical research has the potential to revolutionize drug delivery, providing more efficient and secure treatment choices for a wide range of health-related diseases.

A Focused Low-Intensity Pulsed Ultrasound (FLIPUS) System for Cell Stimulation: Physical and Biological Proof of Principle

Quantitative ultrasound (QUS) is a promising technique for bone tissue evaluation. Highly focused transducers used for QUS also have the capability to be applied for tissue-regenerative purposes and can provide spatially limited deposition of acoustic energy. We describe a focused low-intensity pulsed ultrasound (FLIPUS) system, which has been developed for the stimulation of cell monolayers in the defocused far field of the transducer through the bottom of the well plate. Tissue culture well plates, carrying the cells, were incubated in a special chamber, immersed in a temperature-controlled water tank. A stimulation frequency of 3.6 MHz provided an optimal sound transmission through the polystyrene well plate. The ultrasound was pulsed for 20 min daily at 100-Hz repetition frequency with 27.8% duty cycle. The calibrated output intensity corresponded to I(SATA) = 44.5 ± 7.1 mW/cm2, which is comparable to the most frequently reported nominal output levels in LIPUS studies. No temperature change by the ultrasound exposure was observed in the well plate. The system was used to stimulate rat mesenchymal stem cells (rMSCs). The applied intensity had no apoptotic effect and enhanced the expression of osteogenic markers, i.e., osteopontin (OPN), collagen 1 (Col-1), the osteoblast-specific transcription factor-Runx-2 and E11 protein, an early osteocyte marker, in stimulated cells on day 5. The proposed FLIPUS setup opens new perspectives for the evaluation of the mechanistic effects of LIPUS.

Focused low-intensity pulsed ultrasound enhances bone regeneration in rat calvarial bone defect through enhancement of cell proliferation

A number of studies have reported the therapeutic potential of low-intensity pulsed ultrasound (LIPUS) for induction of bone repair. This study investigated whether bone regeneration might be enhanced by application of focused LIPUS to selectively stimulate fractured calvarial bone. To accomplish this, bone defects were surgically created in the middle of the skull of rats that were subsequently exposed to focused LIPUS. Bone regeneration was assessed by repeated computed tomography imaging after the operation, as well as histologic analysis with calcein, hematoxylin and eosin and proliferating cell nuclear antigen assay. At 6 wk after surgery, bone formation in the focused LIPUS-treated group improved significantly relative to the control. Interestingly, new bone tissue sprouted from focused LIPUS target points. Histologic analysis after exposure to focused LIPUS revealed that proliferating cells were significantly increased relative to the control. Taken together, these results suggest that focused LIPUS can improve re-ossification through enhancement of cell proliferation in calvarial defect sites.