A Combined Experimental/Quantum-Chemical Study of Tetrel, Pnictogen, and Chalcogen Bonds of Linear Triatomic Molecules.

Linear triatomic molecules (CO2, N2O, and OCS) are scrutinized for their propensity to form perpendicular tetrel (CO2 and OCS) or pnictogen (N2O) bonds with Lewis bases (dimethyl ether and trimethyl amine) as compared with their tendency to form end-on chalcogen bonds. Comparison of the IR spectra of the complexes with the corresponding monomers in cryogenic solutions in liquid argon enables to determine the stoichiometry and the nature of the complexes. In the present cases, perpendicular tetrel and pnictogen 1:1 complexes are identified mainly on the basis of the lifting of the degenerate ν 2 bending mode with the appearance of both a blue and a red shift. Van 't Hoff plots of equilibrium constants as a function of temperature lead to complexation enthalpies that, when converted to complexation energies, form the first series of experimental complexation energies on sp1 tetrel bonds in the literature, directly comparable to quantum-chemically obtained values. Their order of magnitude corresponds with what can be expected on the basis of experimental work on halogen and chalcogen bonds and previous computational work on tetrel bonds. Both the order of magnitude and sequence are in fair agreement with both CCSD(T) and DFA calculations, certainly when taking into account the small differences in complexation energies of the different complexes (often not more than a few kJ mol-1) and the experimental error. It should, however, be noted that the OCS chalcogen complexes are not identified experimentally, most probably owing to entropic effects. For a given Lewis base, the stability sequence of the complexes is first successfully interpreted via a classical electrostatic quadrupole-dipole moment model, highlighting the importance of the magnitude and sign of the quadrupole moment of the Lewis acid. This approach is validated by a subsequent analysis of the molecular electrostatic potential, scrutinizing the σ and π holes, as well as the evolution in preference for chalcogen versus tetrel bonds when passing to "higher" chalcogens in agreement with the evolution of the quadrupole moment. The energy decomposition analysis gives further support to the importance/dominance of electrostatic effects, as it turns out to be the largest attractive term in all cases considered, followed by the orbital interaction and the dispersion term. The natural orbitals for chemical valence highlight the sequence of charge transfer in the orbital interaction term, which is dominated by an electron-donating effect of the N or O lone-pair(s) of the base to the central atom of the triatomics, with its value being lower than in the case of comparable halogen bonding situations. The effect is appreciably larger for TMA, in line with its much higher basicity than DME, explaining the comparable complexation energies for DME and TMA despite the much larger dipole moment for DME.

Is It Possible to Increase Flap Viability by Hydrostatic Dilation?: An Experimental Study in the Rat Abdominal Fasciocutaneous Flap Model.

INTRODUCTION: Ergun et al previously demonstrated the efficacy of hydrostatic dilation in a TRAM flap model in an experimental study. We investigated the effect of hydrostatic dilation on a fasciocutaneous flap model. METHODS: Eighteen female Wistar rats were equally divided into 3 groups, of which 1 served as a control. In the second, the abdominal fasciocutaneous flap surgical delay procedure was performed by division of the left superficial inferior epigastric (SIE) vessels. In the third, hydrostatic dilation was performed on the left SIE artery and vein, with a mean pressure of 300 mm Hg, while elevating the flap on the right-sided SIE pedicle. The groups were compared by microangiography and by the survival ratio of abdominal flaps 7 days after elevation. RESULTS: The mean (SD) flap necrosis rates were as follows: control group, 44.75% (4.31%); delay group, 33.32% (7.11%); and hydrostatic dilation group, 32.51% (5.03%). There was a significant difference between the control group and the other 2 groups (P < 0.05). There was no difference between the delay and hydrostatic dilation groups with respect to surface area necrosis. The microangiographies showed remarkable increased vascularity in the delay and hydrostatic dilation groups. CONCLUSIONS: Hydrostatic dilation is a new method of enhancing flap viability that could be used in clinical cases in place of surgical delay once further studies and clinical trials are completed.

Bilobed flap for web reconstruction in adult syndactyly release: a new technique that can avoid the use of skin graft.

AIM: The aim of the study was to describe the use of a bilobed flap for web formation of syndactyly release, which decreases the need for graft and also avoids the use of skin grafting in syndactyly cases. METHODS: A retrospective review of this procedure was performed for 15 web space reconstructions. Patients were aged 20-23 years. The mean follow-up period was 7-12 months (mean 7 + 3.2). The operations were performed for the beneficial use of the dorsal hand skin by lowering the need for a skin graft. The flap was on the dorsum of the hand and proximal phalanx and was used for web formation. RESULTS: Surgery was completed without skin grafting in nine cases of 14 web spaces; two of them were complex/complete syndactylies, and two of them were simple/complete syndactylies. We used a skin graft in one patient because of triangular flap necrosis in a second operation. The use of a bilobed flap allowed the construction of web spaces, providing satisfactory cosmetic outcomes. No partial necrosis or complications was observed in bilobed flaps. No secondary correction was needed during the follow-up period. CONCLUSION: The present surgical technique could be a new surgical option for web formation and reconstruction in primary and secondary cases, especially in an adult population in which the skin on the dorsum of the hand is more pliable. LEVEL OF EVIDENCE: IV.

[Late results of replantations in tip amputations of the thumb]. / Basparmak distal uç amputasyonlarinda replantasyon uygulamalarinin geç dönem sonuçlari.

OBJECTIVES: We retrospectively evaluated replantations performed for Tamai type 1 thumb amputations. METHODS: The study included 14 patients (12 males, 2 females; mean age 28 years; range 14 to 40 years) whose replanted thumbs survived following replantation for Tamai type 1 amputations in the distal nail fold of the thumb. Central digital artery anastomosis was performed in all the cases. Four patients with an appropriate vein had a single volar vein anastomosis. Nerve repair could be possible in only three patients. Sensory evaluations were made with the Semmes-Weinstein monofilament test, static and moving two-point discrimination tests, and vibration test. In addition, patients were evaluated with respect to atrophy in the replanted part, nail-bed deformities, and cold intolerance. The mean follow-up period was 11 months (range 6 to 48 months). RESULTS: The Semmes-Weinstein test was green (range 2.83 to 3.22) in five patients (35.7%), blue (range 3.22 to 3.61) in eight patients (57.1%), and purple (range 3.84 to 4.31) in one patient (7.1%). The mean static and moving two-point discrimination test results were 6.9 mm (range 3 to 10 mm) and 4.5 mm (range 3 to 6 mm), respectively. Compared to the intact fingers, vibration was increased in six thumbs (42.9%), decreased in six thumbs, and the same in two thumbs (14.3%). Atrophy of the replanted parts was observed in five patients (35.7%). Three patients (21.4%) complained about cold intolerance, and three patients had nail-bed deformities. The mean time to return to work was 3.2 months (range 2 to 6 months). CONCLUSION: Despite technical difficulties, thumb replantations yield good functional and aesthetic results. Sensory recovery is sufficient even after tip replantations without nerve repair.

Effect of hydrostatic dilation on flap viability of the transverse rectus abdominis musculocutaneous flap model in rats.

BACKGROUND: The technique of intraoperative vessel hydrostatic dilation is sometimes used to facilitate microvascular anastomosis and prevent vasospasm. Currently, delay procedures remain a reliable method of maximizing flap survival. The authors aimed to increase rat transverse rectus abdominis musculocutaneous (TRAM) flap viability by imitating the physical effect of a surgical delay procedure with hydrostatic dilation. METHODS: Forty-five male Sprague-Dawley rats were randomly assigned to one of three TRAM flap groups (15 rats in each group): the control group, the delay group, and the hydrostatic dilation group. The surgical delay procedure was performed by division of right-sided cranial epigastric vessels and contralateral superficial inferior epigastric vessels. While elevating the flap, hydrostatic dilation was performed to the cranial epigastric artery and vein with a mean pressure of 250 mm Hg. The groups were compared by means of microangiography and survival ratio of TRAM flaps and mean artery lumen area, mean vein lumen area, and mean artery wall area of the flap pedicle 48 hours after elevation. RESULTS: There was a significant difference between the control and hydrostatic dilation groups in favor of surface area viability and angiographic assessment (p < 0.01). Surgical delay has traditionally been accepted as the most reliable method of enhancing flap viability. No significant difference was revealed between the surgical delay and hydrostatic dilation groups (p > 0.05). In the hydrostatic dilation group, compared with the control group, an increase in vein diameter, a thinning of the artery wall, and an increase in lumen diameter were observed. CONCLUSIONS: The physical effect of blood flow is achieved acutely with hydrostatic dilation. This simple, dependable, one-stage hydrostatic dilation procedure can be used in clinical applications.

The effect of hyperbaric oxygen therapy on the delay procedure.

BACKGROUND: This study evaluates the possibility of enhancing the beneficial effect of the delay procedure by using hyperbaric oxygen therapy, and the possibility of lessening the time required for maximal effect of delay procedure. METHODS: Eight male Wistar rats were used in each of 10 groups. The surgical delay method was applied to the caudally based dorsal rat flap by incising the longitudinal borders and undermining the flap. In the first five groups, 3-, 7-, 10-, 14-, and 21-day delay periods were applied, and in the other five groups, hyperbaric oxygen therapy was applied during the delay periods. Blood circulation was measured with a laser Doppler flowmeter, and flap survival lengths were recorded. Histological analysis for vascular counting and determining vascular areas and microangiographic analysis for monitoring vascular status were performed. RESULTS: In addition to the flap viabilities being increased, the maximum effect of the delay procedure could be achieved earlier with hyperbaric oxygen therapy. Blood circulation in the flaps, vascular counts, and vascular areas were increased by applying hyperbaric oxygen during the delay period. Microangiographic results confirmed the beneficial effect of hyperbaric oxygen treatment. CONCLUSIONS: Hyperbaric oxygen treatment during the delay period can lessen the time period needed for the delay procedure and increase the effect of the delay itself.

Reconstruction of a complex intercanthal defect with triple advancement flaps.

A complex intercanthal skin defect, created by resection of a squamous cell carcinoma localised in the nasal root of a 52-year-old man, was successfully reconstructed using three axial pattern advancement flaps raised from the nasal dorsum and paranasal areas.

Camouflage of self-inflicted razor blade incision scars with carbon dioxide laser resurfacing and thin skin grafting.

BACKGROUND: Self-cutting using a razor blade is a type of self-mutilating behavior that leaves permanent and socially unacceptable scars with unique patterns, particularly on the upper extremities and anterior chest wall. These scars are easily recognized in the community and become a source of lifelong guilt, shame, and regret for the self-mutilators. In the presented clinical study, we aimed to investigate the effectiveness of carbon dioxide laser resurfacing and thin skin grafting in camouflaging self-inflicted razor blade incision scars. METHODS: A total of 26 anatomical sites (11 upper arm, 11 forearm, and four anterior chest) of 16 white male patients, whose ages ranged from 20 to 41 years (mean, 23.8 years), were treated between February of 2001 and August of 2003. Detailed psychiatric evaluation preoperatively; informing the patient that the procedure is a "camouflage" operation; trimming hypertrophic scars down to intact skin level; intralesional corticosteroid injection to hypertrophic scars; carbon dioxide laser resurfacing as a single unit; thin (0.2 to 0.3 mm) skin grafting; compressive dressing for 15 days; use of tubular bandage; and protection from sunlight for at least 6 months constituted the key points of the procedure. RESULTS: The scars were successfully camouflaged and converted to a socially acceptable appearance similar to a burn scar. Partial graft loss in one case and hyperpigmentation in another case were the complications. No new hypertrophic scar developed. CONCLUSIONS: The carbon dioxide laser resurfacing and thin skin grafting method is effective in camouflaging self-inflicted razor blade incision scars.

Repair of chronic mallet finger deformity using Mitek micro arc bone anchor.

Surgical correction of chronic mallet finger caused by terminal tendon disruption was carried out in 22 patients. The distal stump of the tendon was fixed to the base of the distal phalanx with a Mitek micro arc bone anchor. In all patients the mallet finger deformity was corrected. There were 15 patients with excellent results, 5 with good results, and 2 with fair results. None of the patients had a poor result. No further treatment was needed. The Mitek micro arc bone anchor system is a reliable alternative for the treatment of chronic mallet finger deformity without proximal interphalangeal hyperextension.

Management of maxillofacial problems in self-inflicted rifle wounds.

Severe gunshot wounds to the face, produced by high-velocity rifles or shotgun blasts, present a formidable challenge to reconstructive surgeons. In this study, the results of 14 cases with gunshot wounded faces caused by fire from rifles are presented, and the principles of the management of those victims were determined. These patients had attempted to commit suicide and placed the muzzles of the rifles beneath their chins. The ages of the patients ranged from 20 to 24 years, with a mean age of 22 years. These wounds were caused by close-range gunshots (<10 cm), and the missiles had high velocity (more than 800 m/second). All patients had wounds in their submental triangle areas. The exit sites of the missiles differed among patients. All exit wounds were in the angle limited by the deviation from the gun-barrel axis. After clinical and radiologic evaluation and conservative debridement of all devitalized tissues, the fractures were reduced and stabilized appropriately. Large bony defects were treated by bone grafting, and all soft tissue lesions were closed in layers. The entrance and exit sites were covered primarily after thorough debridement except one case whose defect was reconstructed with bilateral sternocleidomastoid (SCM) flaps, one for submental skin and the other for the mouth floor. Intraoral soft tissues were then repaired by primary closure, tongue flaps, or SCM flaps in case they were necessary. Free tissue transfers were not required for treatment of secondary soft-tissue problems. Resolution of tissue edema, softening of scars in time, and insertion of bone graft may improve the deformity significantly. The initial anatomic reconstruction of the existing bone skeleton and the maximal use of regional tissue for cutaneous reconstruction provide an esthetic appearance that can never be duplicated by secondary reconstruction.

Various applications of the medial plantar flap to cover the defects of the plantar foot, posterior heel, and ankle.

The medial plantar fasciocutaneous flap provides structurally similar tissue to plantar foot, posterior heel, and ankle defects with its thick glabrous plantar skin, shock-absorbing fibrofatty subcutaneous tissue, and plantar fascia. During the past 4 years, 24 patients (20 men, 4 women) with skin and soft-tissue defects over the plantar foot, posterior heel, or ankle were treated. They ranged in age from 20 to 42 years (mean, 24 y). The medial plantar flap was transposed to the defects in four different ways: proximally pedicled sensorial island flaps (N = 18), reverse-flow island flaps (N = 2), free flaps (N = 2), and cross-foot flaps (N = 2). Flap size varied from a width of 2 to 5.5 cm and a length of 5 to 7.5 cm. The follow-up period ranged from 2 to 18 months (mean, 9 mo). Partial flap loss was observed in one free flap and one reverse-flow island flap. Partial skin graft lost in the donor site required regrafting in one patient. Durable, sensate coverage of the defects was achieved in all patients.

Effect of various nerve decompression procedures on the functions of distal limbs in streptozotocin-induced diabetic rats: further optimism in diabetic neuropathy.

It is known that diabetic neuropathy is the result of endoneurial edema caused by various biochemical reactions triggered by hyperglycemia. This sequence of events can cause cessation of circulation at the perineurial level, or the tough layer, which is not resilient enough to spread intraneural pressure. Internal and external limiting structures create a double crush phenomenon to the nerve structure. Decompression of the nerve trunk at separate levels is one of the adjuncts to the overall treatment plan for diabetic neuropathy. In this study, the right sciatic nerves of 30 rats with streptozotocin-induced diabetes were used; three groups were created. In the control group, the sciatic nerves were explored and dissected only. In group II, tarsal tunnel release was performed and accompanied by epineurotomy of the sciatic nerve and its peroneal and tibial extensions. In group III, in addition to the procedures performed in group II, perineural sheaths, exposed through the epineurotomy sites at both the peroneal and tibial nerves, were incised for decompression of the fascicles. Improvement in diabetic neuropathy was evaluated by using footprint parameters. The last print length values, estimated according to the 38-month measurements, were 26.1 +/- 0.12 mm in the control group, 23.2 +/- 0.07 mm in group II, and 22.2 +/- 0.1 mm in group III. The toe spread and intermediate toe spread values of the groups were parallel to improvements in print lengths throughout the study. The best improvement was observed in the perineurotomy group. Finally, an electron microscopic study revealed variable degenerative changes in all groups, but they were milder in groups II and III. This experimental study reveals that adding internal decompression to external release doubled the effect in reducing derangement in the sciatic nerves of the rats and, in the authors' opinion, offers cause for further optimism in the treatment of diabetic neuropathy.