Active distance control in multi-capsule endoscopy via closed loop electromagnetic force between capsules

Capsule endoscopy offers a non-invasive and patient-friendly method for imaging the gastrointestinal tract, boasting superior tissue accessibility compared to traditional endoscopy and colonoscopy. While advances have led to capsules capable of drug delivery, tactile sensing, and biopsy, size constraints often limit a single capsule from having multifunctionality. In response, we introduce multi-capsule endoscopy, where individually ingested capsules, each with unique functionalities, work collaboratively. However, synchronized navigation of these capsules is essential for this approach. In this paper, we present an active distance control strategy using a closed-loop system. This entails equipping one capsule with a sphere permanent magnet and the other with a solenoid. We utilized a Simulink model, incorporating (i) the peristalsis motion on the primary capsule, (ii) a PID controller, (iii) force dynamics between capsules through magnetic dipole approximation, and (iv) position tracking of the secondary capsule. For practical implementation, Hall effect sensors determined the inter-capsule distance, and a PID controller adjusted the solenoid's current to maintain the desired capsule spacing. Our proof-of-concept experiments, conducted on phantoms and ex vivo bovine tissues, pulled the leading capsule mimicking a typical human peristalsis speed of 1 cm/min. Results showcased an inter-capsule distance of 1.94 mm ± 0.097 mm for radii of curvature at 500 mm, 250 mm, and 100 mm, aiming for a 2-mm capsule spacing. For ex vivo bovine tissue, the achieved distance was 0.97 ± 0.28 mm against a target inter-capsule distance of 1 mm. Through the successful demonstration of precise inter-capsule control, this study paves the way for the potential of multi-capsule endoscopy in future research.

The effect of laser-activated Acidulated Phosphate Fluoride on enamel submitted to erosive solution only: an in vitro preliminary evaluation

AIM

The purpose of this in vitro study was to evaluate the potential effect of laser therapy on the prevention of erosive demineralisation either alone or combined with acidulated phosphate fluoride gel on human enamel. It was hypothesized that such a treatment would decrease enamel solubility.

STUDY DESIGN

Efficacy of 2940 nm Er:YAG laser with preset parameters--alone or combined with APF (Acidulated Phosphate Fluoride) gel--was tested on freshly extracted human permanent molars.

MATERIALS AND METHODS

Ten sound human third molars were sectioned into 5 surfaces (2 x 3 mm) with hard tissue microtome and were randomly allocated into different treatment groups as follows. The Vicker's hardness of each surface was obtained at the baseline. Group 1, negative control group: no treatment. Group 2, positive control group: only 1.23% APF gel (Denti-Care gel, Medicom) 1 minute application. Group 3: irradiated with surface modification mode (2940 nm, 1.2j/cm², 10 Hz, 300 μm) Er:YAG laser. Group 4: Er:YAG laser application following 1.23% APF gel. Group 5: 1.23% APF gel following Er:YAG laser application. The demineralisation process was obtained by immersion of specimens in a soft drink for 10 minutes and then the Vickers hardness was reevaluated.

STATISTICS

For statistical analyses within groups the Kruskal Wallis test was used, while for comparing groups the paired sample t test (significance p<0.05) was used.

RESULTS

The difference in microhardness values of each group obtained following the treatments was not statistically significant (p>0.05). Beside, no statistical difference was found in Vickers value related to the application of fluoride prior or after laser therapy. Conclusion Er:YAG laser irradiation alone or combined with APF decreased the enamel solubility but combined treatment did not show any significant additional effect.

Muscle transposition and skin grafting for salvage of below-knee amputation level after bilateral lower extremity thermal injury

Thermal injury to the lower extremity sometimes necessitates amputation around the knee joint. Knee function is so critical to prosthetic rehabilitation that every attempt should be made to salvage the knee joint. This report presents an unusual case of bilateral lower extremity flame burn requiring amputations. While the distal two-thirds of the legs and both feet were totally necrotic, the thermal damage was limited to skin and subcutaneous tissue sparing muscle and bone in the proximal one-third of the legs and posterior thighs. The below-knee amputation level was salvaged by muscle transposition over the anterior tibia and resurfacing of muscle cuffs with thick split-thickness skin grafts. The post-operative period was uneventful. Amputation stumps tolerated the below-knee prosthesis well and the patient attained independent functional prosthetic ambulation at the post-operative fourth month. It is known from the reconstruction of the plantar foot that skin-grafted muscle tissue tolerates weight bearing and shearing forces well. This principle can also be used for salvage aspects of the below-knee amputation level.

Skin grafting of the naso-orbital region as a single aesthetic unit

With improved acute care, a higher percentage of more severely injured facial burn patients are surviving their burns. When the full face needs resurfacing, total facial resurfacing should ideally be done with a single sheet of full-thickness skin. Unfortunately, this type of single sheet total facial resurfacing is rarely possible or practical in the case of acute extensive burns. The nasoorbital region is a focal point of interpersonal communication and needs special emphasis. This report presents two patients with deep facial burns whose midface regions were resurfaced with thick split-thickness skin graft as a single aesthetic unit. Since there is no skin graft junction line on this region, a more homogeneous appearance and an aesthetically superior result could be achieved.

A different strategy in the surgical treatment of capsular contracture: leave capsule intact

The authors present their experience with the surgical treatment of capsular contracture to achieve better results in a safe, predictable, and practical way, and discuss the possible treatment modalities. They simply advise leaving the capsule intact, even if it is calcified, and create another pocket, rarely in the front or, more typically, at the back of the capsule. If the breast tissue is also ptotic, a mastopexy procedure may be added to the procedure, in addition to augmentation, with a rather small prosthesis placed in the new pocket or, occasionally, in the old one. External, forceable massage is not advisable to treat the capsule. Open capsulotomy and/or partial capsulectomy can be applied to release the capsule. However, it is not advisable since recurrence is usually inevitable. The purpose of this paper is to present a series of surgical procedures to avoid the problems created by the capsule and present different cases with good results.

Nerve regeneration through an epineurial sheath: its functional aspect compared with nerve and vein grafts

Although nerve graft is still the only reliable choice in repair of defects in peripheral nerve structure, it has the disadvantage of donor nerve morbidity and of sometimes being unavailable. It has long been researched in alternate nerve grafts with other materials. Studies have shown that nerves could regenerate across short nerve gaps through various conduits, such as veins, pseudosheaths, and bioabsorbable tubes. Despite encouraging studies, their functional results remain unclear. The present study used 40 rats, in which nerve grafts, vein grafts, and epineurial tubes were placed into 1-cm gaps in sciatic nerves created by resection. In one group, sciatic nerves were denuded of the surrounding epineurium, to assess the possible morbidity caused by epineurial sheath technique. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed using walking track analysis. The number of myelinated fibers and fiber diameters was measured and electron microscopic evaluation performed. Functionally, the index values were very close to each other in nerve graft and epineurial sheath groups. Morphometric analysis showed significance between the groups. The result of denuded sciatic nerve group was the same as the base track values. It was concluded that the ready availability of epineurial sheath as a conduit to span short nerve gaps could eliminate the morbidity associated with nerve graft harvest and capitalize on the potential benefits of neurotrophism in directing nerve regeneration.

Unsatisfactory results of periareolar mastopexy with or without augmentation and reduction mammoplasty: enlarged areola with flattened nipple

A method of repair is described for correction of abnormally enlarged nipple-areola complex following both periareolar mastopexy and pregnancy. Although during periolar mastopexy or reduction mammoplasty regular subcuticular dermal sutures may control the enlargement of nipple-areola complexes initially, the periareolar scar becomes hypertrophic and areolar spreading occurs to some extent. Periareolar mastopexy techniques are indeed advisable only for minimal hypertrophies or ptosis of the breast, especially for areolar asymmetry, if an acceptable, normal-size areola is expected. The authors believe that in periolar mastopexy or reduction mammoplasty cases resulting in enlarged nipple-areola complexes, the size of the areola can also be corrected by reduction mammoplasty or mastopexy using vertical bipedicle techniques. Although surgery results in an inverted T incision, the shape of the breast is more acceptable and the size of the areola does not enlarge with time.

"Tandir": an old and well known cause of burn injury in the Middle East

Analysis of an unusual cause of burn injury together with assessment of long-term end results was carried out. The 'tandir' is a kind of oven buried underground and resembles a big hole full of embers and surrounded with sheet iron. Most of the burn victims were children. 68 major burn cases have been admitted to our units in a 3 year period, 32 (47%) of them due to a 'tandir'. In most of the cases burn injuries included the head and both hands as a result of the specific characteristics of the 'tandir'.