Rate and Location of Reulceration and Reamputation After Partial First-Ray Amputation versus Hallux Amputation in Diabetic and Nondiabetic Populations.

BACKGROUND: We sought to determine the rates of reulceration and reamputation in individuals who underwent partial first-ray amputations versus hallux amputations in diabetic and nondiabetic populations. METHODS: Eighty-four amputations were reviewed in a retrospective fashion. A retrospective medical record review was performed to determine patients who underwent a hallux amputation, both partial and complete, and patients who underwent a partial first-ray amputation. Only patients from 2007 to 2019 were reviewed. The reulceration rate of hallux amputations was 61% compared with a partial first-ray amputation reulceration rate of 74%. RESULTS: The reamputation rate of hallux amputation versus partial first-ray amputation was 43% versus 51%. At final follow-up, it was statistically significant that patients who underwent hallux amputation were more likely to be healed than those who underwent partial first-ray amputation, regardless of reulceration or reamputation. In addition, patients who underwent hallux amputation went on to digital amputation, and those who underwent partial first-ray amputation went on to transmetatarsal amputation. CONCLUSIONS: Comparing partial first-ray amputation to hallux amputation, hallux amputation patients are more prone to subsequent digital ulceration. Patients who initially undergo hallux amputation have variable subsequent amputations, often digital. Reulceration primarily occurs at the incision site for partial first-ray amputations, with a higher likelihood of subsequent transmetatarsal amputation. Patients with a medical history of diabetes and staged procedures are more likely to receive partial first-ray amputations. However, hallux amputation patients have a lower risk of reulceration and reamputation, regardless of subsequent events. These findings underscore the importance of discussing risks and preventive measures with patients undergoing such amputations, emphasizing postoperative examinations for specific areas of concern. Hallux amputation appears to offer greater protection against reulceration and reamputation for both diabetic and nondiabetic populations.

Effects of Conformational Variation on Structural Insights from Solution-Phase Surface-Enhanced Raman Spectroscopy.

Surface-enhanced Raman scattering (SERS) spectra contain information on the chemical structure on nanoparticle surfaces through the position and alignment of molecules with the electromagnetic near field. Time-dependent density functional theory (TDDFT) can provide the Raman tensors needed for a detailed interpretation of SERS spectra. Here, the impact of molecular conformations on SERS spectra is considered. TDDFT calculations of the surfactant cetyltrimethylammonium bromide with five conformers produced more accurate unenhanced Raman spectra than a simple all-trans structure. The calculations and measurements also demonstrated a loss of structural information in the CH2/CH3 scissor vibration band at 1450 cm-1 in the SERS spectra. To study lipid bilayers, TDDFT calculations on conformers of methyl phosphorylcholine and cis-5-decene served as models for the symmetric choline stretch in the lipid headgroup and the C═C stretch in the acyl chains of 1,2-oleoyl-glycero-3-phosphocholine. Conformer considerations enabled a measurement of the distribution of double-bond orientations with an order parameter of SC═C = 0.53.

The orientation of a membrane probe from structural analysis by enhanced Raman scattering.

Small fluorescent molecules are widely used as probes of biomembranes. Different probes optically indicate membrane properties such as the lipid phase, thickness, viscosity, and electrical potential. The detailed molecular mechanisms behind probe signals are not well understood, in part due to the lack of tools to determine probe position and orientation in the membrane. Optical measurements on aligned biomembranes and lipid bilayers provide some degree of orientational information based on anisotropy in absorption, fluorescence, or nonlinear optical properties. These methods typically find the polar tilt angle between the membrane normal and the long axis of the molecule. Here we show that solution-phase surface enhanced Raman scattering (SERS) spectra of lipid membranes on gold nanorods can be used to determine molecular orientation of molecules within the membrane. The voltage sensitive dye 4-(2-(6-(dibutylamino)-2-naphthalenyl)ethenyl)-1-(3-sulfopropyl)-hydroxide, known as di-4-ANEPPS, is studied. Through the analysis of several peaks in the SERS spectrum, the polar angle from the membrane normal is found to be 66°, and the roll angle around the long axis of the molecule to be 305° from the original orientation. This structural analysis method could help elucidate the meaning of fluorescent membrane probe signals, and how they are affected by different lipid compositions.