The Structure of the "Vibration Hole" around an Isotopic Substitution-Implications for the Calculation of Nuclear Magnetic Resonance (NMR) Isotopic Shifts.

Calculations of nuclear magnetic resonance (NMR) isotopic shifts often rest on the unverified assumption that the "vibration hole", that is, the change of the vibration motif upon an isotopic substitution, is strongly localized around the substitution site. Using our recently developed difference-dedicated (DD) second-order vibrational perturbation theory (VPT2) method, we test this assumption for a variety of molecules. The vibration hole turns out to be well localized in many cases but not in the interesting case where the H/D substitution site is involved in an intra-molecular hydrogen bond. For a series of salicylaldehyde derivatives recently studied by Hansen and co-workers (Molecules 2019, 24, 4533), the vibrational hole was found to stretch over the whole hydrogen-bond moiety, including the bonds to the neighbouring C atoms, and to be sensitive to substituent effects. We discuss consequences of this finding for the accurate calculation of NMR isotopic shifts and point out directions for the further improvement of our DD-VPT2 method.

Saphenous nerve transfer: A new approach to restore sensation of the sole.

BACKGROUND: Loss of protective sensation of the sole may lead to repeated trauma, chronic nonhealing ulcers, and even amputation. Saphenous nerve (SN) to posterior tibial nerve (PTN) transfer can restore sensation of the sole. METHOD: This study was conducted in a tertiary referral center in Central India. Twenty-one patients (32 feet) diagnosed with loss of sensation of the sole were included in this study. Causes of loss of sensation were Hansen's disease (n = 18), complex sciatic nerve injury (n = 1), lumbosacral spinal tumor (n = 1), and lumbosacral meningomyelocele (n = 1). Seventeen feet (14 patients) had ulcers on the sole. Preoperative and postoperative sensory tests performed on the sole included tests for touch, pain, temperature, pressure, vibration, and two-point discrimination. Results were classified as per the British Medical Research Council (MRC) scoring system. RESULTS: Seventeen patients (26 feet) were available for follow-up at 6 months after surgery. All patients had improvement in sensory parameters. Ulcers completely healed in 13 feet and reduced in size in four feet. MRC score improved from S0 in 22 feet and S1 in 10 feet to S3 + in 20 feet, S3 in four feet, and S2 in two feet. CONCLUSIONS: Sensory neurotization with SN transfer to PTN can restore protective sensation to the sole and help in the healing of ulcers.

Can people affected by leprosy at risk of developing plantar ulcers be identified? A field study from central Ethiopia.

In the ALERT leprosy control programme, 75 people affected by leprosy, in three different geographical areas, were investigated. Each person was documented as having anaesthesia to the 10 g monofilament. The study sought to determine why some people developed ulcers whilst others did not. According to the records, 43 had an ulcer during the last 5 years but 32 had never had an ulcer. In order to examine protective sensation on the sole of the foot, various sensory modalities were tested and the functional anatomy of the foot was examined. The results showed, as may be expected, that it is not possible to define a specific threshold for protective sensation that could be applied to all cases. Some people with only slightly diminished sensation developed ulcers, while many others with almost complete anaesthesia remained ulcer-free. In these rural communities, being a farmer reduced the risk of developing an ulcer, but no other demographic features were significant. Graded monofilaments were found to be the most appropriate test, with loss of sensation at any of five points tested being a 'positive' result. The 10 g filament was the most sensitive, but only 43% of feet identified by this test actually developed an ulcer. As people with partial loss of sensation were excluded from this study, this figure may be lower under programme conditions. The 50 g and 100 g filaments decrease the number of feet identified as at risk, but increase the percentage which actually develop an ulcer, to 46% and 49%, respectively. An appropriate test for selecting those for special programmes which may have a limited capacity, for example the provision of subsidized footwear or involvement in self-care groups, would be a 100 g filament, which would detect 86% of those feet likely to develop an ulcer, while reducing the number of those selected who are not at great risk. Vibrometry was found to be no better than graded filaments and an examination of functional anatomy did not help in identifying those at risk.

Vibration sense and tarsal disintegration.

The extent of loss of vibration and pressure sensations was assessed in 21 leprosy patients with disintegration of the tarsus. Feet which had and did not have tarsal disintegration both showed severe impairment of pressure sensation, but the loss of vibration sense was more severe in feet which had undergone the destructive process. It appears that loss of deep sensation is an important factor in the process of tarsal disintegration in feet which are already anaesthetic. Measurement of vibration sense using a biosthesiometer may be a valuable clinical test in the investigation and follow-up of the patient with the insensitive foot to identify those at risk of developing tarsal disintegration.