Diabetic neuropathy and the sensory apparatus "meissner corpuscle and merkel cells"

Skin Sensitivity Assessment Using Smartphone Haptic Feedback

Goal: This work presents a smartphone application to assess cutaneous sensory perception by establishing Vibrational Perception Thresholds (VPTs). Cutaneous sensory perception diagnostics allow for the early detection and symptom tracking of tactile dysfunction. However, lack of access to healthcare and the limited frequency of current screening tools can leave skin sensation impairments undiscovered or unmonitored. Methods: A 23-participant cross-sectional study in subjects with a range of finger sensation tests Smartphone Established VPTs (SE-VPTs) by varying device vibrational intensity. These are compared against monofilament test scores, a clinical measure of skin sensitivity. Results: We find a strong positive correlation between SE-VPTs and monofilament scores ([Formula: see text] = 0.86, p = 1.65e-07). Conclusions: These results demonstrate the feasibility of using a smartphone as a skin sensation screening tool.

Addition of adipose tissue-derived mesenchymal stem cells improves empagliflozin therapy for alleviating hyperglycemia--induced neuropathy

BACKGROUND

We examined the impact of adipose-derived mesenchymal stem cell (ADMSC)-facilitated empagliflozin (EMPA) therapy for alleviating hyperglycemic induced neuropathy [i.e., diabetic neuropathy (DN)].

METHODS

Study constituted N2a cell culture and rats to be classified into groups 1 (sham-operated-control)/2 (DN)/3 (DN + empagliflozin/20 mg/kg/daily orally for 6 weeks since post-day-7 DN induction)/4 (DN + ADMSCs/1.2 × 106 cells by vein transfusion at time intervals of 1/3/5 weeks after DN induction)/5 (DN + empagliflozin + ADMSCs) and sacrificed by day-42 after DN induction.

RESULTS

In vitro results showed that, compared to N2a cells, the cellular levels of senescence/DNA-damage and protein expressions of oxidative-stress (OS), apoptotic, autophagic and inflammatory biomarkers were significantly higher in N2a + glucose (25 mM) but were significantly reversed in N2a + glucose + ADMSCs, whereas the cellular levels of mitochondrial cytochrome C and protein levels of anti-oxidants displayed an opposite pattern of OS (all P<0.001). The above-mentioned parameters (i.e., OS/apoptosis/fibrosis/autophagy/DNA-damage) were lowest in N2a cells, highest in N2a + glucose and significantly higher in N2a + glucose + EMPA (50 μM) than in N2a + glucose + EMPA (150 μM) (all P<0.001). By days 7/14/21/28/35/42 after DN induction, the values of thermal paw-withdrawal-latency (TPWL)/mechanical-paw-withdrawal-threshold were highest in group 1 and significantly progressively increased from groups 2/4/3/5 (all P<0.0001). The cellular levels of unmyelinated C- and myelinated A-δ fibers, and protein levels of OS/apoptotic/DNA-damaged/fibrotic/autophagic/inflammatory/pain-facilitated/voltage-gated sodium channel biomarkers in L4-L5 levels of dorsal-root-ganglia exhibited an contradictory manner of TPWL among the groups (all P<0.0001).

CONCLUSIONS

Combination of EMPA and ADMSC therapy was superior to either alone for improving outcomes of DN.

Adherence and the Diabetic Foot: High Tech Meets High Touch?

Diabetic foot ulcers, which are a common complication of diabetes, can have a negative impact on a person's physical and mental health, including an increased risk of depression. Patients suffering from depression are less likely to keep up with diabetic foot care, thus increasing the risk of developing ulcers. However, with the use of artificial intelligence (AI), at-home patient care has become easier, which increases adherence. To better understand how new technologies, including machine learning algorithms and wearable sensors, might improve patient adherence and outcomes, we conducted a literature review of several sensor technologies, including SmartMat© and Siren Care© socks for temperature, SurroSense Rx/Orpyx© for pressure, and Orthotimer© for adherence. An initial search identified 143 peer-reviewed manuscripts, from which we selected a total of 10 manuscripts for further analysis. We examined the potential benefits of personalized content and clinician support for those receiving mobile health interventions. These findings may help to demonstrate the current and future utility of advanced technologies in improving patient adherence and outcomes, particularly in the context of diabetes management and the link between behavior and complications in diabetes, such as diabetic foot ulcers.

Lipohypertrophy in Elderly Insulin-Treated Patients With Type 2 Diabetes

BACKGROUND

The number of older adults with insulin-treated diabetes mellitus (DM) is steadily increasing worldwide. Errors in the insulin injection technique can lead to skin lipohypertrophy (LH), which is the accumulation of fat cells and fibrin in the subcutaneous tissue. While lipohypertrophic lesions/nodules (LHs) due to incorrect insulin injection techniques are very common, they are often flat and hardly visible and thus require thorough deep palpation examination and ultrasonography (US) for detection. Detection is crucial because such lesions may eventually result in poor diabetes control due to their association with unpredictable insulin release patterns. Skin undergoes fundamental structural changes with aging, possibly increasing the risk for LH. We have therefore investigated the effect of age on the prevalence of LHs and on factors potentially associated with such lesions.

METHODS

A total of 1227 insulin-treated outpatients with type 2 DM (T2DM) referred to our diabetes centers were consecutively enrolled in the study. These patients underwent a thorough clinical and US evaluation of the skin at injection sites, as previously described, with up to 95% concordance betweenthe clinical and US screening techniques. Of these 1227 patients, 718 (59%) had LH (LH+) and 509 (41%) were LH-free (LH-). These patients were then assigned to two age class groups (≤ 65 years and > 65 years), and several clinical features, diabetes complication rates, and injection habits were investigated.

RESULTS

Comparison of the two age subgroups revealed that 396 (48%) and 322 (79%) patients in the younger and older groups, respectively, had LHs (p < 0.001). Compared to the younger subgroup, the older subgroup displayed a higher LH rate in the abdomen (52.9 vs. 38.3%; p < 0.01) and a lower rate in the arms (25.4 vs. 35.8%; p < 0.05), thighs (26.7 vs. 33.4%; p < 0.05), and buttocks (4.9 vs. 26.2%; p < 0.01). In older subjects, the most relevant parameters were: habit of injecting insulin into LH nodules (56 vs. 47% [younger subjects]; p < 0.01), rate of post-injection leakage of insulin from injection site (drop-leaking rate; 47 vs. 39% [younger subjects]; p < 0.05), and rate of painful injections (5 vs. 16% [younger subjects]; p < 0.001). Multivariate analysis showed a stronger association between LH and poor habits, as well as between several clinical parameters, among which the most relevant were hypoglycemic events and glycemic variability.

DISCUSSION

The higher rate of post-injection drop-leaking and pain-free injections might find an explanation in skin changes typically observed in older adults, including lower thickness, vascularity and elasticity, and a more prominent fibrous texture, all of which negatively affect tissue distensibility. Consequently, in addition to the well-known association between aging skin impaired drug absorption rate, aging skin displays a progressively decreasing ability to accommodate large volumes of insulin-containing fluid.

CONCLUSIONS

The strong association between LH rate and hypoglycemic events plus glycemic variability suggests the need (1) to take specific actions to prevent and control the high risk of acute cardiovascular events expected to occur in older subjects in the case of hypoglycemic events, and (2) to identify suitable strategies to fulfill the difficult task of performing effective educational programs specifically targeted to the elderly.

TRIAL REGISTRATION

Trial registration number 172-11:12.2019, Scientific and Ethical Committee of Campania University "Luigi Vanvitelli", Naples, Italy).

Computational Parametric Analysis of the Mechanical Response of Structurally Varying Pacinian Corpuscles

The Pacinian corpuscle (PC) is a cutaneous mechanoreceptor that senses low-amplitude, high-frequency vibrations. The PC contains a nerve fiber surrounded by alternating layers of solid lamellae and interlamellar fluid, and this structure is hypothesized to contribute to the PC's role as a band-pass filter for vibrations. In this study, we sought to evaluate the relationship between the PC's material and geometric parameters and its response to vibration. We used a spherical finite element mechanical model based on shell theory and lubrication theory to model the PC's outer core. Specifically, we analyzed the effect of the following structural properties on the PC's frequency sensitivity: lamellar modulus (E), lamellar thickness (h), fluid viscosity (μ), PC outer radius (Ro), and number of lamellae (N). The frequency of peak strain amplification (henceforth "peak frequency") and frequency range over which strain amplification occurred (henceforth "bandwidth") increased with lamellar modulus or lamellar thickness and decreased with an increase in fluid viscosity or radius. All five structural parameters were combined into expressions for the relationship between the parameters and peak frequency, ωpeak=1.605×10-6N3.475(Eh/μRo), or bandwidth, B=1.747×10-6N3.951(Eh/μRo). Although further work is needed to understand how mechanical variability contributes to functional variability in PCs and how factors such as PC eccentricity also affect PC behavior, this study provides two simple expressions that can be used to predict the impact of structural or material changes with aging or disease on the frequency response of the PC.

In-vivo reflectance confocal microscopy of Meissner's corpuscles in diabetic distal symmetric polyneuropathy

OBJECTIVE

To evaluate in-vivo reflectance confocal microscopy (RCM) of Meissner's corpuscles (MC) in diabetic distal symmetric polyneuropathy (DSP).

METHODS

Forty-three adults with diabetes and 21 control subjects underwent RCM of MC density at the fingertip of digit V, thenar eminence (TE), and arch of the foot, ankle skin biopsy for epidermal nerve fiber density (ENFD), electrophysiological studies, monofilament threshold testing, and timed vibration at the toe. Subjects with diabetes were subdivided into groups with and without clinical DSP using the American Academy of Neurology (AAN) case definition and neuropathy outcomes were compared across groups.

RESULTS

Both diabetic groups (with and without AAN clinical DSP criteria) had objective evidence of peripheral sensory involvement using conventional sensory measures, although those with clinical DSP criteria had greater abnormalities. MC densities were lower in the entire diabetic group at the TE and digit V relative to controls. MC densities at all imaging sites were associated with corresponding conventional sensory measures. MC densities were reduced in subjects without AAN clinical DSP criteria at the TE and digit V compared to controls whereas conventional upper limb sensory measures did not differ between these groups.

CONCLUSIONS

In-vivo RCM of MC density at digit V is a non-invasive, painless, objective marker in diabetes that offers a window into early large fiber sensory nerve terminal loss. Further studies are needed to determine whether RCM of MCs can identify quantitative changes in DSP associated with disease progression or treatment.