Microcirculatory vasomotor changes are associated with severity of peripheral neuropathy in patients with type 2 diabetes

Clinical physiology: the crucial role of MRI in evaluation of peripheral artery disease

Peripheral artery disease (PAD) is a common vascular disease that primarily affects the lower limbs and is defined by the constriction or blockage of peripheral arteries and may involve microvascular dysfunction and tissue injury. Patients with diabetes have more prominent disease of microcirculation and develop peripheral neuropathy, autonomic dysfunction, and medial vascular calcification. Early and accurate diagnosis of PAD and disease characterization are essential for personalized management and therapy planning. Magnetic resonance imaging (MRI) provides excellent soft tissue contrast and multiplanar imaging capabilities and is useful as a noninvasive imaging tool in the comprehensive physiological assessment of PAD. This review provides an overview of the current state of the art of MRI in the evaluation and characterization of PAD, including an analysis of the many applicable MR imaging techniques, describing the advantages and disadvantages of each approach. We also present recent developments, future clinical applications, and future MRI directions in assessing PAD. The development of new MR imaging technologies and applications in preclinical models with translation to clinical research holds considerable potential for improving the understanding of the pathophysiology of PAD and clinical applications for improving diagnostic precision, risk stratification, and treatment outcomes in patients with PAD.

Research progress of the effective active ingredients of Astragalus mongholicus in the treatment of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is one of the most prevalent consequences of diabetes, with a high incidence and disability rate. The DPN's pathogenesis is extremely complex and yet to be fully understood. Persistent high glucose metabolism, nerve growth factor deficiency, microvascular disease, oxidative stress, peripheral nerve cell apoptosis, immune factors, and other factors have been implicated in the pathogenesis of DPN. Astragalus mongholicus is a commonly used plant used to treat DPN in clinical settings. Its rich chemical components mainly include Astragalus polysaccharide, Astragalus saponins, Astragalus flavones, etc., which play a vital role in the treatment of DPN. This review aimed to summarize the pathogenesis of DPN and the studies on the mechanism of the effective components of Astragalus mongholicus in treating DPN. This is of great significance for the effective use of Chinese herbal medicine and the promotion of its status and influence on the world.

Differences in peripheral microcirculatory blood flow regulation in chronic kidney disease based on wavelet analysis of resting near-infrared spectroscopy

Vascular impairment is closely related to increased mortality in chronic kidney disease (CKD). The objective of this study was to assess impairments in the regulation of peripheral microvascular perfusion in patients with CKD based on time-frequency spectral analysis of resting near-infrared spectroscopy (NIRS) signals. Total hemoglobin (tHb) concentration and tissue saturation index (TSI) signals were collected using NIRS for a continuous 5 mins at 10 Hz from the forearm of 55 participants (34 CKD including 5 with end-stage renal disease, and 21 age-matched control). Continuous wavelet transform-based spectral analysis was used to quantify the spectral amplitude within five pre-defined frequency intervals (I, 0.0095-0.021 Hz; II, 0.021-0.052 Hz; III, 0.052-0.145 Hz; IV, 0.145-0.6 Hz and V, 0.6-2.0 Hz), representing endothelial, neurogenic, myogenic, respiratory and heartbeat activity, respectively. CKD patients showed lower tHb average spectral amplitude within the neurogenic frequency interval compared with controls (p = 0.014), consistent with an increased sympathetic outflow observed in CKD. CKD patients also showed lower TSI average spectral amplitude within the endothelial frequency interval compared with controls (p = 0.046), consistent with a reduced endothelial function in CKD. These findings demonstrate the potential of wavelet analysis of NIRS to provide complementary information on peripheral microvascular regulation in CKD.

Contactless photoplethysmography for assessment of small fiber neuropathy

Chronic pain is a prevalent condition affecting approximately one-fifth of the global population, with significant impacts on quality of life and work productivity. Small fiber neuropathies are a common cause of chronic pain, and current diagnostic methods rely on subjective self-assessment or invasive skin biopsies, highlighting the need for objective noninvasive assessment methods. The study aims to develop a modular prototype of a contactless photoplethysmography system with three spectral bands (420, 540, and 800 nm) and evaluate its potential for assessing peripheral neuropathy patients via a skin topical heating test and spectral analyses of cutaneous flowmotions. The foot topical skin heating test was conducted on thirty volunteers, including fifteen healthy subjects and fifteen neuropathic patients. Four cutaneous nerve fiber characterizing parameters were evaluated at different wavelengths, including vasomotor response trend, flare area, flare intensity index, and the spectral power of cutaneous flowmotions. The results show that neuropathic patients had significantly lower vasomotor response (50%), flare area (63%), flare intensity index (19%), and neurogenic component (54%) of cutaneous flowmotions compared to the control group, independent of photoplethysmography spectral band. An absolute value of perfusion was 20%-30% higher in the 420 nm band. Imaging photoplethysmography shows potential as a cost-effective alternative for objective and non-invasive assessment of neuropathic patients, but further research is needed to enhance photoplethysmography signal quality and establish diagnostic criteria.

Diabetic neuropathy results in vasomotor dysfunction of medium sized peripheral arteries

BACKGROUND

The effect of the sympathetic nervous system on peripheral arteries causes vasoconstriction when smooth muscle cells in the walls of blood vessels contract, which leads to narrowing of arteries and reduction of the blood flow.

AIM

To compare sympathetic vasomotor activation of the brachial arteries in healthy subjects and patients with painful diabetic neuropathy; and therefore, to assess whether there is significant vasomotor dysfunction of medium sized arteries in diabetic neuropathy.

METHODS

The study included 41 diabetic neuropathy patients and 41 healthy controls. Baseline diameter and flow rate of the brachial arteries were measured. Then, using a bipolar stimulus electrode, a 10 mA, 1 Hz electrical stimulus was administered to the median nerve at the wrist level for 5 s. The brachial artery diameter and blood flow rate were re-measured after stimulation.

RESULTS

In the control group, the median flow rate was 70.0 mL/min prior to stimulation and 35.0 mL/min after stimulation, with a statistically significant decrease (P < 0.001), which is consistent with sympathetic nervous system functioning (vasoconstriction). In the diabetic neuropathy group, median flow rate before the stimulation was 35.0 mL/min. After stimulation, the median flow rate was 77.0 mL/min; thus, no significant decrease in the flow rate was detected. In the control group, the median brachial artery diameter, which was 3.6 mm prior to stimulation, decreased to 3.4 mm after stimulation, and this decrease was also statistically significant (P = 0.046). In the diabetic neuropathy group, the median brachial artery diameter increased from 3.4 mm to 3.6 mm following nerve stimulation. Once again, no narrowing was observed.

CONCLUSION

Our research suggests that diabetic neuropathy results in significant vasomotor dysfunction of medium sized peripheral arteries. Physiological vasoconstriction in response to sympathetic activation is impaired in diabetic neuropathy.

Diabetic neuropathy results in vasomotor dysfunction of medium sized peripheral arteries

BACKGROUND

The effect of the sympathetic nervous system on peripheral arteries causes vasoconstriction when smooth muscle cells in the walls of blood vessels contract, which leads to narrowing of arteries and reduction of the blood flow.

AIM

To compare sympathetic vasomotor activation of the brachial arteries in healthy subjects and patients with painful diabetic neuropathy; and therefore, to assess whether there is significant vasomotor dysfunction of medium sized arteries in diabetic neuropathy.

METHODS

The study included 41 diabetic neuropathy patients and 41 healthy controls. Baseline diameter and flow rate of the brachial arteries were measured. Then, using a bipolar stimulus electrode, a 10 mA, 1 Hz electrical stimulus was administered to the median nerve at the wrist level for 5 s. The brachial artery diameter and blood flow rate were re-measured after stimulation.

RESULTS

In the control group, the median flow rate was 70.0 mL/min prior to stimulation and 35.0 mL/min after stimulation, with a statistically significant decrease (P < 0.001), which is consistent with sympathetic nervous system functioning (vasoconstriction). In the diabetic neuropathy group, median flow rate before the stimulation was 35.0 mL/min. After stimulation, the median flow rate was 77.0 mL/min; thus, no significant decrease in the flow rate was detected. In the control group, the median brachial artery diameter, which was 3.6 mm prior to stimulation, decreased to 3.4 mm after stimulation, and this decrease was also statistically significant (P = 0.046). In the diabetic neuropathy group, the median brachial artery diameter increased from 3.4 mm to 3.6 mm following nerve stimulation. Once again, no narrowing was observed.

CONCLUSION

Our research suggests that diabetic neuropathy results in significant vasomotor dysfunction of medium sized peripheral arteries. Physiological vasoconstriction in response to sympathetic activation is impaired in diabetic neuropathy.

Microvascular reactivity using laser Doppler measurement in type 2 diabetes with subclinical atherosclerosis

Microangiopathy should be noted in diabetes with subclinical vascular diseases. Little is known about whether various surrogate markers of systemic arterial trees exacerbate simultaneously in preclinical atherosclerosis. To clarify the association of skin microvascular reactivity with arterial stiffness is essential to elucidating early atherosclerotic changes. The post-occlusive reactive hyperemia of skin microcirculation was evaluated in 27 control and 65 type 2 diabetic subjects, including 31 microalbuminuria (MAU) and 34 normoalbuminuria (NAU) patients. The laser Doppler skin perfusion signals were transformed into three frequency intervals for the investigation of endothelial, neurogenic, and myogenic effects on basal and reactive flow motion changes. The analysis of spectral intensity and distribution provided insight into potential significance of microvascular regulation in subclinical atherosclerotic diseases. Systemic arterial stiffness was studied by the brachial ankle pulse wave velocity (baPWV). Following occlusive ischemia, the percent change of endothelial flow motion was lower in MAU than in NAU and control groups. The MAU group revealed a relative increase in myogenic activity and a decrease in endothelial activity in normalized spectra. The baPWV showed more significant associations with reactive endothelial change (r = - 0.48, P < 0.01) and normalized myogenic value (r = - 0.37, P < 0.05) than diabetes duration and HbA1c. By multivariate regression analysis, only endothelial vasomotor changes independently contributed to the decreased baPWV (OR 3.47, 95% CI 1.63-7.42, P < 0.05). Impaired microcirculatory control is associated with increased arterial stiffness in preclinical atherosclerosis. To identify the early manifestations is necessary for at-risk patients to prevent from further vascular damage.

Infrared thermographic changes after decompression surgery in patients with carpal tunnel syndrome

BACKGROUND

Digital infrared thermal imaging (DITI), which detects infrared rays emitted from body surface to create a body heat map, has been utilized at various musculocutaneous conditions. Notably, DITI can demonstrate autonomic vasomotor activity in the nerve-innervated area, and thus may be of use in carpal tunnel syndrome (CTS). In this study, we compared DITI findings before and after carpal tunnel release (CTR) surgery in patients with unilateral CTS to investigate the corresponding neurophysiological changes.

METHODS

In this retrospective cohort study, DITI parameters such as the temperature differences between the median and ulnar nerve territories and median nerve-innervated digital anisometry were measured. Subjective symptom duration, pain scale, and ultrasonographic findings were also compared before and after CTR. Patients were evaluated before and 6 weeks after CTR, respectively.

RESULTS

A total of 27 patients aged 59.0 ± 11.2 years were finally included. After CTR, median nerve-innervated thermal anisometry was improved (2.55 ± 0.96 °C to 1.64 ± 1.34 °C; p = 0.003). The temperature differences between the median and ulnar nerve territories were not significantly changed. Subjective pain, the Simovic Weinberg Clinical Scale, and palmar bowing of the flexor retinaculum were also significantly improved (p <  0.001 for all comparisons).

CONCLUSIONS

Our results demonstrated that DITI findings could reflect an improvement in autonomic function after CTR. Therefore, DITI can be an objective method to assess pre- and post-operative neurophysiologic changes in CTS.

Skin autofluorescence corresponds to microvascular reactivity in diabetes mellitus

Advanced glycation accelerated by chronic hyperglycaemia contributes to the development of diabetic vascular complications throughout several mechanisms. One of these mechanisms is supposed to be impaired microvascular reactivity, that precedes significant vascular changes. The aim of this study was to find an association between advanced glycation, the soluble receptor for AGEs (sRAGE), and microvascular reactivity (MVR) in diabetes. Skin autofluorescence (SAF), which reflects advanced glycation, was assessed by AGE-Reader, MVR was measured by laser Doppler fluxmetry and evaluated together with sRAGE in 43 patients with diabetes (25 Type 1 and 18 Type 2) and 26 healthy controls of comparable age. SAF was significantly higher in patients with diabetes compared to controls (2.4 ± 0.5 vs. 2.0 ± 0.5 AU; p < 0.01). Patients with diabetes with SAF > 2.3 AU presented significantly worse MVR in both post-occlusive reactive hyperaemia (PORH) on the finger and forearm, and thermal hyperaemia (TH), compared to patients with SAF < 2.3 AU. SAF was age dependent in both diabetes (r = 0.41, p < 0.01) and controls (r = 0.45, p < 0.05). There was no association between SAF and diabetes control expressed by glycated haemoglobin. A significant relationship was observed between SAF and sRAGE in diabetes (r = 0.56, p < 0.001), but not in controls. A significant inverse association was found between SAF and MVR on the forearm in diabetes (PORH: r = -0.42, p < 0.01; TH: r = -0.46, p < 0.005). Both advanced glycation expressed by higher SAF or sRAGE and impaired MVR are involved in the pathogenesis of vascular complications in diabetes, and we confirm a strong interplay of these processes in this scenario.

Alterations in plantar vessel blood flow in patients with mild diabetic peripheral neuropathy

INTRODUCTION

Early identification and treatment of diabetic peripheral neuropathy (DPN) are crucial. Presently, the mechanism of DPN is not very clear, and there are inconclusive conclusions about the influencing factors of vascular dynamic characteristics in DPN. This study aims to detect and compare the hemodynamic characteristics of plantar blood vessels in patients with mild DPN and healthy participants to explore a simple and reliable new idea and a potential method for early assessment of DPN and to investigate the influence of gender and age on hemodynamic characteristics.

RESEARCH DESIGN AND METHODS

Sixty age-matched and gender-matched patients with mild DPN (30 men and 30 women) and 60 healthy participants were randomly recruited. Color Doppler ultrasound was used to measure and analyze the hemodynamic characteristics of plantar-related vessels.

RESULTS

Ultrasonic measurements had good test-retest reliability. There may be no statistically significant differences in the blood flow velocity and blood flow in the plantar-related blood vessels of participants, irrespective of their gender and age. For patients with mild DPN, color Doppler ultrasound may indicate early hemodynamic abnormalities when there are no obvious abnormalities in the large arteries of the lower limbs, which are specifically manifested as increased blood flow velocity and blood flow in the distal small vessels.

CONCLUSIONS

Our study provides in vivo data support for the dynamic characteristics of the plantar blood vessel biomechanical model and provides a new idea of in vivo and non-invasive early diagnosis of DPN.

Vasomotion analysis of speed resolved perfusion, oxygen saturation, red blood cell tissue fraction, and vessel diameter: Novel microvascular perspectives

BACKGROUND

Vasomotion is the spontaneous oscillation in vascular tone in the microcirculation and is believed to be a physiological mechanism facilitating the transport of blood gases and nutrients to and from tissues. So far, Laser Doppler flowmetry has constituted the gold standard for in vivo vasomotion analysis.

MATERIALS AND METHODS

We applied vasomotion analysis to speed-resolved perfusion, oxygen saturation, red blood cell tissue (RBC) tissue fraction, and average vessel diameter from five healthy individuals at rest measured by the newly developed Periflux 6000 EPOS system over 10 minutes. Magnitude scalogram and the time-averaged wavelet spectra were divided into frequency intervals reflecting endothelial, neurogenic, myogenic, respiratory, and cardiac function.

RESULTS

Recurrent high-intensity periods of the myogenic, neurogenic, and endothelial frequency intervals were found. The neurogenic activity was considerably more pronounced for the oxygen saturation, RBC tissue fraction, and vessel diameter signals, than for the perfusion signals. In a correlation analysis we found that changes in perfusion in the myogenic, neurogenic, and endothelial frequency intervals precede changes in the other signals. Furthermore, changes in average vessel diameter were in general negatively correlated to the other signals in the same frequency intervals, indicating the importance of capillary recruitment.

CONCLUSION

We conclude that vasomotion can be observed in signals reflecting speed resolved perfusion, oxygen saturation, RBC tissue fraction, and vessel diameter. The new parameters enable new aspects of the microcirculation to be observed.

Application of digital infrared thermography for carpal tunnel syndrome evaluation

We investigated the thermographic findings of carpal tunnel syndrome (CTS). We enrolled 304 hands with electrodiagnostically identified CTS and 88 control hands. CTS hands were assigned to duration groups (D1, < 3 months; D2, 3‒6 months; D3, 6‒12 months; D4, ≥ 12 months) and severity groups (S1, very mild; S2, mild; S3, moderate; S4, severe). The temperature difference between the median and ulnar nerve territories (ΔM-U territories) decreased as CTS duration and severity increased. Significant differences in ΔM-U territories between the D1 and D3, D1 and D4, D2 and D4, and S1 and S4 groups (P = 0.003, 0.001, 0.001, and < 0.001, respectively) were observed. Thermal anisometry increased as CTS duration and severity increased. Significant differences in thermal anisometry between the D1 and D4 as well as the D2 and D4 groups (P = 0.005 and 0.04, respectively) were noted. Thermal anisometry was higher in the S4 group than in the S1, S2, and S3 groups (P = 0.009, < 0.001, and 0.003, respectively). As CTS progresses, skin temperature tends to decrease and thermal variation tends to increase in the median nerve-innervated area. Thermographic findings reflect the physiological changes of the entrapped median nerve.

Concomitant Peripheral Neuropathy and Type 2 Diabetes Impairs Postexercise Cutaneous Perfusion and Flowmotion

CONTEXT

Type 2 diabetes and peripheral neuropathy exhibit microvascular dysfunction at rest. However, data regarding their microvascular perfusion during exercise remain scarce.

OBJECTIVE

This study investigated changes in microvascular perfusion during postexercise recovery in those with type 2 diabetes, with or without peripheral neuropathy, as well as in healthy controls and those with obesity.

METHODS

Skin blood perfusion was assessed in each group using laser Doppler flowmetry (LDF) and laser speckle contrast imaging before and immediately after a 6-minute walking test. LDF recordings underwent wavelet transformation to allow specific control mechanisms of blood perfusion to be studied (eg, endothelial nitric oxide-independent and -dependent, neurogenic, myogenic, respiratory, and cardiac mechanisms).

RESULTS

Skin blood perfusion increased after exercise in all groups (22.3 ± 28.1% with laser speckle contrast imaging and 22.1 ± 52.5% with LDF). Throughout postexercise recovery, the decrease was blunted in those with subclinical peripheral neuropathy and confirmed peripheral neuropathy when compared to the other 3 groups. After exercise, total spectral power increased in all groups. The relative contributions of each endothelial band was lower in those with confirmed peripheral neuropathy than in the healthy controls and those with obesity (nitric oxide-dependent function: 23.6 ± 8.9% vs 35.5 ± 5.8% and 29.3 ± 8.8%, respectively; nitric oxide-independent function: 49.1 ± 23.7% vs 53.3 ± 10.4% and 64.6 ± 11.4%, respectively). The neurogenic contribution decreased less in those with confirmed peripheral neuropathy and in those with type 2 diabetes alone, compared to those with subclinical peripheral neuropathy and those with obesity (-14.5 ± 9.9% and -12.2 ± 6.1% vs -26.5 ± 4.7% and -21.7 ± 9.4%, respectively).

CONCLUSION

Peripheral neuropathy, whatever the stage, altered the microvascular response to exercise via impaired endothelial and neurogenic mechanisms.

Proportion and severity of periodontitis and correlation of periodontal inflamed surface area with glycemic status in patients with type 2 diabetic neuropathy with and without diabetic foot

BACKGROUND

The association between diabetic neuropathy with and without diabetic foot and periodontitis remains unaddressed in the literature. The present study was conducted to evaluate the frequency of patients with periodontitis and its severity, and to correlate clinical attachment loss (AL) and periodontal inflamed surface area (PISA) with HbA1c in Type 2 Diabetic Neuropathy (T2DN) patients with and without diabetic foot.

METHODS

In this cross-sectional study 310 patients with type 2 diabetic neuropathy (T2DN) were randomly selected, and the study comprised of 120 patients with T2DN with diabetic foot and 155 patients with T2DN without diabetic foot. All patients were assessed for periodontal parameters (bleeding on probing, probing depth, clinical AL, oral hygiene index-simplified), plaque index, and PISA) and systemic parameters (HbA1c, fasting blood glucose, post prandial blood glucose, urinary albumin creatine ratio, erythrocyte sedimentation rate, and high-sensitivity C-reactive protein).Unpaired t-test and Chi-Square test were used to analyze quantitative data and qualitative data, respectively.

RESULTS

The frequency of patients with periodontitis in patients with T2DN with and without diabetic foot was 91.7% and 88.4%, respectively. The severity of periodontitis, PISA, and clinical AL were higher in the diabetic foot group. Clinical AL and PISA were significantly related with HbA1c in patients with T2DN with and without diabetic foot.

CONCLUSIONS

Percentage of patients with periodontitis and the severity of periodontal destruction were high in type 2 diabetic neuropathy with diabetic foot. A significant correlation of PISA, clinical AL with glycemic status was found in patients with T2DN with and without diabetic foot.

Reduced microvascular reactivity in patients with diabetic neuropathy

BACKGROUND

Neurogenic regulation is involved in the development of microcirculation response to local heating. We suggest that microvascular reactivity can be used to estimate the severity of diabetic polyneuropathy (DPN).

OBJECTIVE

To evaluate the prospects for using the parameters of skin microvascular reactivity to determine the severity of DPN.

METHODS

26 patients with diabetes mellitus were included in the study (patients with retinopathy (n = 15), and without retinopathy (n = 11)). The severity of DPN was assessed using Michigan Neuropathy Screening Instrument (MNSI) and Norfolk QOL-DN (NQOLDN). Skin microcirculation was measured by laser Doppler flowmetry with local heating test.

RESULTS

There were revealed moderate negative correlations between microvascular reactivity and the severity of DPN (for MNSI (Rs = -0.430), for NQOLDN (Rs = -0.396)). In patients with retinopathy, correlations were stronger than in the general group (for MNSI (Rs = -0.770) and NQOLDN (Rs = -0.636)). No such correlations were found in patients without retinopathy.

CONCLUSION

Correlation of the microvascular reactivity and DPN was revealed in patients with registered structural disorders in microvessels (retinopathy). The lack of such correlation in patients without retinopathy may be explained by the intact compensatory mechanisms of microvessels without severe disorders.

Remote Photoplethysmography for Evaluation of Cutaneous Sensory Nerve Fiber Function

About 2% of the world’s population suffers from small nerve fiber dysfunction, neuropathy, which can result in severe pain. This condition is caused by damage to the small nerve fibers and its assessment is challenging, due to the lack of simple and objective diagnostic techniques. The present study aimed to develop a contactless photoplethysmography system using simple instrumentation, for objective and non-invasive assessment of small cutaneous sensory nerve fiber function. The approach is based on the use of contactless photoplethysmography for the characterization of skin flowmotions and topical heating evoked vasomotor responses. The feasibility of the technique was evaluated on volunteers (n = 14) using skin topical anesthesia, which is able to produce temporary alterations of cutaneous nerve fibers function. In the treated skin region in comparison to intact skin: neurogenic and endothelial component of flowmotions decreased by ~61% and 41%, the local heating evoked flare area decreased by ~44%, vasomotor response trend peak and nadir were substantially reduced. The results indicate for the potential of the remote photoplethysmography in the assessment of the cutaneous nerve fiber function. It is believed that in the future this technique could be used in the clinics as an affordable alternative to laser Doppler imaging technique.

Vasomodulation of peripheral blood flow by focused ultrasound potentiates improvement of diabetic neuropathy

OBJECTIVE

Effective treatment methods for diabetic peripheral neuropathy are still lacking. Here, a focused ultrasound (FUS) technique was developed to improve blood flow in diabetic peripheral vessels and potentially treat diabetic peripheral neuropathy.

RESEARCH DESIGN AND METHODS

Male adult Sprague-Dawley rats at 4 weeks poststreptozotocin injections were adopted as models for diabetic neuropathic rats. For single FUS treatment, blood perfusion in the skin of the pad of the middle toe was measured before, during, and after the medial and lateral plantar arteries were treated by FUS. For multiple FUS treatments, blood perfusion measurements, von Frey and hot plate testing and nerve conduction velocity measurements were performed before ultrasonic treatment on the first day of each week, and the microvascular and neural fiber densities in the pad of the toe were measured on the first day of the last week.

RESULTS

The blood perfusion rate significantly increased for 7-10 min in the control and neuropathic rats after a single ultrasound exposure. Multiple ultrasound treatments compared with no treatments significantly increased blood perfusion at the second week and further enhanced perfusion at the third week in the neuropathic rats. Additionally, the paw withdrawal force and latency significantly increased from 34.33±4.55 g and 3.96±0.25 s at the first week to 39.10±5.02 g and 4.77±0.71 s at the second week and to 41.13±2.57 g and 5.24±0.86 s at the third week, respectively. The low nerve conduction velocity in the diabetic rats also improved after the ultrasound treatments. Additionally, ultrasound treatments halted the decrease in microvessel and neural fiber densities in the skin of the diabetic toes. Histologic analysis indicated no damage to the treated arteries or neighboring tissue.

CONCLUSIONS

FUS treatment can increase upstream arterial blood flow in diabetic feet, ameliorate the decrease in downstream microvessel perfusion and halt neuropathic progression.

Prevalence of Diabetic Foot Ulcer and Associated Factors among Adult Diabetic Patients on Follow-Up Clinic at Jimma Medical Center, Southwest Ethiopia, 2019: An Institutional-Based Cross-Sectional Study

BACKGROUND

Diabetic foot ulceration is a devastating complication of diabetes mellitus and is a major source of morbidity and mortality. So far, there are few published data on diabetic foot ulcers and its determinants among diabetic patients on follow-up at Jimma Medical Center. Hence, the aim of this study was to assess the prevalence of diabetic foot ulcer and its determinants among patients with diabetes mellitus at Jimma Medical Center.

METHODS

A hospital-based cross-sectional study was conducted from June 1 to August 30, 2019, and systematic random sampling technique was applied. The total number of study subjects who participated in the study was 277. Data were collected using an interview-administered structured questionnaire. Data were entered into EpiData version 3.1 and exported to SPSS version 20 software for analysis. Analysis was done using descriptive statistics and logistic regression. A variable having a p value of <0.25 in the bivariate model was subjected to multivariate analysis to avoid confounding the variable's effect. Adjusted odds ratios (AOR) were calculated at 95% confidence interval and considered significant with a p value of <0.25 in the bivariate model was subjected to multivariate analysis to avoid confounding the variable's effect. Adjusted odds ratios (AOR) were calculated at 95% confidence interval and considered significant with a.

RESULT

The mean of age of participants was 50.1 ± 14.19 years. More than three-fourths of participants (82.7%) were type 2 DM. The mean duration of diabetic patients was 6.00 ± 5.07 years. The prevalence of diabetic foot ulcer was 11.6% among study participants. According to multivariate logistic regression analysis, previous history of ulceration (AOR = 5.77; 95% CI: 2.37, 14.0) and peripheral neuropathy (AOR = 11.2; 95% CI: 2.8, 44.4) were independent predictors of diabetic foot ulcer.

CONCLUSION

The prevalence of diabetic foot ulcer was 11.6%. Previous history of ulceration and peripheral neuropathy were associated with diabetic foot ulcer. The health care providers are recommended to thoroughly give emphasis during follow-up of patients who had previous history of ulceration and peripheral neuropathy in order to decrease the occurrence of diabetic foot ulcer.

A new approach to the analysis of skin blood flow oscillations in human

It is considered that there are six non-overlapping frequency intervals with constant boundaries. These intervals correspond to different mechanisms of skin blood flow regulation. The boundaries do not depend on functional conditions but this statement should be verified. Also it remains unclear how the oscillatory components of skin blood flow are related. Thus the study is aimed to verify statistically the boundaries of frequency intervals, to test the hypothesis that the boundaries depend on age and to search for relationships between spectral components of skin blood flow. The study involved 105 healthy volunteers aged from 20 to 65 years, which were divided into two age groups. Skin blood flow was registered with laser Doppler flowmeter (LDF). Assessments of frequency interval boundaries and relationship between the frequency oscillatory components of blood flow were conducted with histogram approach, bootstrap method and correlation analysis. New frequency interval boundaries were found. They were different in two groups. A linear correlation and frequency areas with moderate (0.5-0.7) and high (>0.7) correlation coefficients were found between spectral components of blood flow. The dependence of these correlations on the age was shown. Thus we proposed a conceptually new approach to analysis of spectral components of skin microhemodynamics and interpretation of results obtained by laser Doppler techniques. This approach is the result of the development of modern understanding of relationships between skin blood flow regulation mechanisms and spectral components of LDF signals. It allows one to have a new look at these relationships as well as demonstrates their dependence on the functional state of the organism as a whole.

Aerobic exercise training may improve nerve function in type 2 diabetes and pre-diabetes: A systematic review

Diabetic neuropathy is a major complication of type 2 diabetes. Emerging evidence also suggests that people with pre-diabetes may develop similar symptoms related to nerve dysfunction. While regular exercise provides many benefits to patients with diabetes, whether exercise influences nerve function has not been established. As such, the aim of this systematic review was to evaluate current evidence regarding the effect of exercise training on the progression and development of diabetic neuropathy. A systematic search of MEDLINE (Ovid), CINAHL, AMED, PEDro, the Cochrane Library, Embase, and Scopus databases identified a total of 12 studies that were eligible for inclusion in this systematic review. Quality rating and data extraction were performed by two independent reviewers. The 12 included studies examined people with pre-diabetes (n = 1) and with type 2 diabetes (n = 11). There was heterogeneity of study quality and exercise type and dosage among these studies. Eleven studies reported that exercise training had a positive influence on nerve function or neuropathy-related symptoms; and only one study reported mild adverse events. Evidence from this systematic review suggests aerobic exercise training may positively influence nerve function among people with type 2 diabetes, with minimal risk of adverse events. Further research will be required to determine the optimal dosage of exercise training and the effect on nerve function in pre-diabetes and in women with previous gestational diabetes. This review is registered on PROSPERO (CRD42018088182).

Role of neopterin as a biochemical marker for peripheral neuropathy in pediatric patients with type 1 diabetes: Relation to nerve conduction studies

BACKGROUND

Neopterin, a marker of inflammation and cellular immune response, is elevated in conditions of T-cell or macrophages activation. Diabetic peripheral neuropathy (DPN) is associated with inflammatory/immune processes and therefore, we hypothesized that neopterin could be used as a marker of neuropathy in type 1 diabetes mellitus (T1DM).

AIM

To measure neopterin levels in children and adolescents with T1DM and assess its possible relation to DPN and nerve conduction studies (NCS).

METHODS

Sixty patients aged ≤18 years and >5 years disease duration were subjected to neurological assessment by neuropathy disability score (NDS) and NCS for median, ulnar, posterior tibial and common peroneal nerves. Mean fasting blood glucose, lipid profile, HbA1c, high sensitivity C-reactive protein (hs-CRP) and serum neopterin levels were assessed. Patients were compared with 30 age- and sex-matched healthy controls.

RESULTS

The frequency of DPN according to NDS was 40 (66.7%) patients out of 60 while NCS confirmed that only 30 of those 40 patients had this complication (i.e. 50% out of the total studied patients). Neopterin levels were significantly higher in patients with DPN than those without (median [IQR], 53.5 [35-60] nmol/L versus 17 [13-32] nmol/L) and healthy controls (5.0 [3.2-7.0] nmol/L) (p < 0.001). Significant positive correlations were found between neopterin levels and HbA1c (r = 0.560, p = 0.005), serum creatinine (r = 0.376, p = 0.003), total cholesterol (r = 0.405, p = 0.026) and hs-CRP (r = 0.425, p = 0.012) among patients with DPN. Neopterin levels were positively correlated to motor latency of tibial and common peroneal nerves as well as motor and sensory latencies of median and ulnar nerves. Logistic regression analysis revealed that neopterin was a significant independent variable related to DPN (Odds ratio, 2.976). Neopterin cutoff value 32 nmol/L could differentiate patients with and without DPN with 100% sensitivity and 96.7% specificity.

CONCLUSIONS

Neopterin could be used as an early reliable serum biomarker for DPN in pediatric patients with T1DM.

Laser Doppler: A Tool for Measuring Pancreatic Islet Microvascular Vasomotion In Vivo

As a functional status of microcirculation, microvascular vasomotion is important for the delivery of oxygen and nutrients and the removal of carbon dioxide and waste products. The impairment of microvascular vasomotion might be a crucial step in the development of microcirculation-related diseases. In addition, the highly vascularized pancreatic islet is adapted to support endocrine function. In this respect, it seems possible to infer that the functional status of pancreatic islet microvascular vasomotion might affect pancreatic islet function. Analyzing the pathological changes of the functional status of pancreatic islet microvascular vasomotion may be a feasible strategy to determine contributions that pancreatic islet microcirculation makes to related diseases, such as diabetes mellitus, pancreatitis, etc. Therefore, this protocol describes using a laser Doppler blood flow monitor to determine the functional status of pancreatic islet microvascular vasomotion, and to establish parameters (including average blood perfusion, amplitude, frequency, and relative velocity of pancreatic islet microvascular vasomotion) for evaluation of the microcirculatory functional status. In a streptozotocin-induced diabetic mouse model, we observed an impaired functional status of pancreatic islet microvascular vasomotion. In conclusion, this approach for assessing pancreatic islet microvascular vasomotion in vivo may reveal mechanisms relating to pancreatic islet diseases.

Flow motion dynamics of microvascular blood flow and oxygenation: Evidence of adaptive changes in obesity and type 2 diabetes mellitus/insulin resistance

An altered spatial heterogeneity and temporal stability of network perfusion can give rise to a limited adaptive ability to meet metabolic demands. Derangement of local flow motion activity is associated with reduced microvascular blood flow and tissue oxygenation, and it has been suggested that changes in flow motion activity may provide an early indicator of declining, endothelial, neurogenic, and myogenic regulatory mechanisms and signal the onset and progression of microvascular pathophysiology. This short conference review article explores some of the evidence for altered flow motion dynamics of blood flux signals acquired using laser Doppler fluximetry in the skin in individuals at risk of developing or with cardiometabolic disease.

Determination of Skeletal Muscle Microvascular Flowmotion with Contrast-Enhanced Ultrasound

Most methods of assessing flowmotion (rhythmic oscillation of blood flow through tissue) are limited to small sections of tissue and are invasive in tissues other than skin. To overcome these limitations, we adapted the contrast-enhanced ultrasound (CEUS) technique to assess microvascular flowmotion throughout a large region of tissue, in a non-invasive manner and in real time. Skeletal muscle flowmotion was assessed in anaesthetised Sprague Dawley rats, using CEUS and laser Doppler flowmetry (LDF) for comparison. Wavelet transformation of CEUS and LDF data was used to quantify flowmotion. The α-adrenoceptor antagonist phentolamine was infused to predictably blunt the neurogenic component of flowmotion. Both techniques identified similar flowmotion patterns, validating the use of CEUS to assess flowmotion. This study demonstrates for the first time that the novel technique of CEUS can be adapted for determination of skeletal muscle flowmotion in large regions of skeletal muscle.

Cilostazol Can Increase Skin Oxygen Supply Assessed by Transcutaneous Oxygen Pressure Measurement in Type 2 Diabetes With Lower Limb Ischemic Disease: A Randomized Trial

PURPOSE

The purpose of this study was to compare the efficacy and safety of cilostazol versus acetylsalicylic acid (ASA) for amelioration of lower limb ischemia in type 2 diabetes.

DESIGN

Prospective, randomized positive-controlled open clinical trial.

SUBJECTS AND SETTING

Eighty-nine patients with type 2 diabetes mellitus and symptoms of lower limb ischemia (perceptions of coldness of the lower limbs, numbness, intermittent claudication, or pain at rest) present for 6 months or more that had not significantly changed within the past 3 months participated in the study. All subjects had an initial transcutaneous oxygen pressure (TcpO2) of less than 40 mm Hg in the foot when measured in the supine position. Subjects included 46 males and 43 females; their ages ranged from 35 to 80 years.

METHODS

Participants were randomly allocated to 2 groups, one was treated with cilostazol 100 mg taken twice daily (n = 48), and a second group took 100 mg of ASA daily (n = 41) for 8 weeks. Clinical assessment included measurement of transcutaneous oxygenation, and symptoms associated with lower limb ischemia. Blood analyses included a full blood panel, coagulation screen, renal function tests, hepatic function tests, and lipid profiles. All tests were performed at baseline and repeated at 8 weeks.

RESULTS

Age, duration of diabetes, diabetic complications, lower limb ischemic symptoms, TcpO2, and smoking status did not differ between the 2 groups. In contrast, TcpO2 significantly improved from 37.1 ± 11.9 mm Hg to 42.0 ± 9.7 mm Hg in the cilostazol-treated group (P < .05), whereas no significant change was observed in the ASA-treated group (P > .05). Ischemic symptoms such as intermittent claudication (P = .009), perception of limb coldness (P = .008), and pain at rest (P = .017) showed greater improvement in the cilostazol-treated group when compared to subjects treated with ASA. Approximately 10% of patients treated with cilostazol experienced adverse side effects (palpitations, headache, diarrhea). Cilostazol was not found to have significant detrimental effects in hematologic or biochemical indices, including renal, hepatic, and blood coagulant function tests.

CONCLUSIONS

We found that 8 weeks of treatment with cilostazol 100 mg daily was safe and well tolerated for the treatment of type 2 diabetes with lower limb ischemic disease.

Correlations between endothelial function in the systemic and cerebral circulation and insulin resistance in type 2 diabetes mellitus

Insulin resistance is associated with endothelial dysfunction in type 2 diabetes mellitus, which can lead to impaired vascular reactivities of both systemic and cerebral circulations. Appropriate 'correction' of vascular reactivity results for non-endothelium-dependent systemic effects avoids misinterpretation of endothelial function. Therefore, we 'corrected' vascular reactivity results and explored the potential correlations between systemic vascular reactivity, cerebrovascular reactivity and insulin resistance. In 34 patients, 'systemic vascular reactivity' was assessed by quantifying reactive hyperaemia. Cerebrovascular reactivity was assessed by quantifying changes in cerebral blood flow velocity during hypercapnia. To minimize the influence of non-endothelium-dependent systemic effects on vascular reactivity results, 'corrected systemic vascular reactivity' was calculated by normalizing systemic vascular reactivity using the measurements from the contralateral side; and cerebrovascular reactivity results were corrected by calculating percentage and absolute changes in cerebrovascular conductance index ('percent cerebrovascular conductance index' and 'delta cerebrovascular conductance index', respectively). Insulin resistance was estimated by homeostatic model assessment. Correlation between conventional cerebrovascular reactivity and systemic vascular reactivity was not significant. But correlations between 'corrected systemic vascular reactivity' and 'percent cerebrovascular conductance index' (r = 0.51; p = 0.002) and 'corrected systemic vascular reactivity' and 'delta cerebrovascular conductance index' (r = 0.50; p = 0.003) were significant. Among all vascular reactivity parameters, only 'delta cerebrovascular conductance index' was significantly correlated with homeostatic model assessment of insulin resistance (r = -0.38; p = 0.029). In conclusion, endothelial function in the systemic and cerebral circulations is moderately correlated, provided that vascular reactivity estimates are corrected for non-endothelium-dependent influences.

Influence of age, gender, and race on nitric oxide release over acupuncture points-meridians

This study examined the influence of age, gender and race on nitric oxide (NO) release over acupuncture points, meridian without acupoint, and non-meridian regions of the Pericardium (PC) and Bladder (BL) meridian as well as aging on LU meridian in 61 healthy subjects. Biocapture tubes were attached to the skin surface, and total nitrite and nitrate was biocaptured and quantified using chemiluminescence. In elder ages compared to adults, NO levels over the ventral forearm were significantly decreased over LU on radial regions but not altered over PC on medial regions. Conversely, NO content was elevated over BL regions only in overweight/obesity of elder ages. NO levels over PC regions were marginally elevated in overweight/obese males compared to females but did not alter between races. These results suggest a selective reduction of NO release over LU meridian with aging, which is consistent with a progressive decline in lung function and increase in chronic respiratory disease in elder ages. Increased NO levels along the BL meridian in older obese subjects may reflect a modified NO level along somatic-bladder pathway for counteracting bladder dysfunctions with aging. Both of them support somatic-organ connections in the meridian system associated with potential pathophysiological changes with aging.

Endurance, interval sprint, and resistance exercise training: impact on microvascular dysfunction in type 2 diabetes

Type 2 diabetes (T2D) alters capillary hemodynamics, causes capillary rarefaction in skeletal muscle, and alters endothelial and vascular smooth muscle cell phenotype, resulting in impaired vasodilatory responses. These changes contribute to altered blood flow responses to physiological stimuli, such as exercise and insulin secretion. T2D-induced microvascular dysfunction impairs glucose and insulin delivery to skeletal muscle (and other tissues such as skin and nervous), thereby reducing glucose uptake and perpetuating hyperglycemia and hyperinsulinemia. In patients with T2D, exercise training (EX) improves microvascular vasodilator and insulin signaling and attenuates capillary rarefaction in skeletal muscle. EX-induced changes subsequently augment glucose and insulin delivery as well as glucose uptake. If these adaptions occur in a sufficient amount of tissue, and skeletal muscle in particular, chronic exposure to hyperglycemia and hyperinsulinemia and the risk of microvascular complications in all vascular beds will decrease. We postulate that EX programs that engage as much skeletal muscle mass as possible and recruit as many muscle fibers within each muscle as possible will generate the greatest improvements in microvascular function, providing that the duration of the stimulus is sufficient. Primary improvements in microvascular function occur in tissues (skeletal muscle primarily) engaged during exercise, and secondary improvements in microvascular function throughout the body may result from improved blood glucose control. We propose that the added benefit of combined resistance and aerobic EX programs and of vigorous intensity EX programs is not simply "more is better." Rather, we believe the additional benefit is the result of EX-induced adaptations in and around more muscle fibers, resulting in more muscle mass and the associated microvasculature being changed. Thus, to acquire primary and secondary improvements in microvascular function and improved blood glucose control, EX programs should involve upper and lower body exercise and modulate intensity to augment skeletal muscle fiber recruitment. Under conditions of limited mobility, it may be necessary to train skeletal muscle groups separately to maximize whole body skeletal muscle fiber recruitment.

Small-Fiber Neuropathy: A Diabetic Microvascular Complication of Special Clinical, Diagnostic, and Prognostic Importance

Damage of small nerve fibers may lead to a large variety of clinical symptoms. Small-fiber neuropathy underlies the symptoms of painful diabetic neuropathy, which may decrease quality of life. It also contributes to the poor prognosis of diabetic neuropathy because it plays a key role in the pathogenesis of foot ulceration and autonomic neuropathy. Impairment of small nerve fibers is considered the earliest alteration in the course of diabetic neuropathy. Therefore, assessment of functional and morphological abnormalities of small nerve fibers may enable timely diagnosis. The definition, symptoms, and clinical significance of small-fiber neuropathy are considered in the present review. An apparently more complex interaction between small-fiber impairment and microcirculation is extensively discussed. Diagnostic modalities include morphometric and functional methods. Corneal confocal microscopy and punch skin biopsy are considered gold standards, but noninvasive functional tests are also diagnostically useful. However, in routine clinical practice, small-fiber neuropathy is diagnosed by its typical clinical presentation. Finally, prompt treatment should be initiated following diagnosis.

Amplitude of sensory nerve action potential in early stage diabetic peripheral neuropathy: an analysis of 500 cases

Early diagnosis of diabetic peripheral neuropathy is important for the successful treatment of diabetes mellitus. In the present study, we recruited 500 diabetic patients from the Fourth Affiliated Hospital of Kunming Medical University in China from June 2008 to September 2013: 221 cases showed symptoms of peripheral neuropathy (symptomatic group) and 279 cases had no symptoms of peripheral impairment (asymptomatic group). One hundred healthy control subjects were also recruited. Nerve conduction studies revealed that distal motor latency was longer, sensory nerve conduction velocity was slower, and sensory nerve action potential and amplitude of compound muscle action potential were significantly lower in the median, ulnar, posterior tibial and common peroneal nerve in the diabetic groups compared with control subjects. Moreover, the alterations were more obvious in patients with symptoms of peripheral neuropathy. Of the 500 diabetic patients, neural conduction abnormalities were detected in 358 cases (71.6%), among which impairment of the common peroneal nerve was most prominent. Sensory nerve abnormality was more obvious than motor nerve abnormality in the diabetic groups. The amplitude of sensory nerve action potential was the most sensitive measure of peripheral neuropathy. Our results reveal that varying degrees of nerve conduction changes are present in the early, asymptomatic stage of diabetic peripheral neuropathy.

Transcutaneous oxygen pressure (TcPO₂): a novel diagnostic tool for peripheral neuropathy in type 2 diabetes patients

AIMS

The assessment of transcutaneous oxygen pressure (TcPO2) may serve as a non-invasive and lower-cost alternative to nerve conduction studies (NCSs) for the diagnosis of diabetic peripheral neuropathy (DPN). The aim of this study was to determine whether the measurement of TcPO2 is useful for evaluating DPN.

METHODS

We performed a cross-sectional study of 381 consecutive hospitalized diabetic patients classified by clinical examination and NCS as having DPN. Anthropometric and metabolic parameters were assessed. The TcPO2 examination was performed in both supine and sitting positions.

RESULTS

Three hundred and one patients had DPN. The TcPO2 in both the supine and sitting positions was highest in the Non-DPN group and lower in the confirmed DPN group than the other three groups (p<0.001). The Non-DPN group had the lowest sitting-supine position difference in TcPO2 among the groups (p<0.001). The risk factors strongly associated with DPN included sitting-supine position difference in TcPO2 (OR=4.971, p<0.001), diabetic retinopathy (DR) (odds ratio [OR]=3.794, p=0.002), and HbA1c (OR=1.534, p=0.033). The area under the curve (AUC) of the sitting-supine position difference in TcPO2 was 0.722 and revealed an optimal cut-off point for the identification of DPN (19.5 mmHg) that had a sensitivity of 0.611 and a specificity of 0.738 based on AUC analysis.

CONCLUSIONS

This large study of diabetic patients confirms that the sitting-supine position difference in TcPO2 is higher in DPN patients than control subjects, indicating that TcPO2 examination is a promising valuable diagnostic tool for DPN.

Microvascular dysfunction in the context of diabetic neuropathy

Microvascular dysfunction in diabetes plays a crucial role in the development of diabetic complications. The skin, as one of the most accessible organs, serves as a model for the investigation of microvascular dysfunction. Several non-invasive, mostly laser-Doppler-based methods have been developed lately to assess microvascular function in the skin. Microvascular functional changes occur even in the prediabetic state and become more complex with overt diabetes, being exacerbated by the presence of peripheral and/or autonomic diabetic neuropathy. The present article aims at shedding light on the implication of endothelial and neurovascular dysfunction in microvascular changes in diabetes, highlighting the contribution of different forms of diabetic neuropathy.