Telemedical Monitoring of Plantar Temperature in Diabetic Patients at Risk of Foot Ulcers.

BACKGROUND: The worldwide prevalence of diabetic foot ulcers (DFUs) among persons with diabetes is estimated at 6.3%, with an annual incidence of 9.1 to 26.1 million persons. The early detection of asymmetrical plantar temperature elevation, followed by reduction of weight-bearing on the affected foot, may be an effective mode of prevention. METHODS: Patients with diabetes and peripheral neuropathy (DFU risk groups 2/3) were monitored for plantar abnormalities with a telemedical system consisting of sole inserts with temperature sensors and photographic documentation. An open, prospective, randomized controlled trial was performed to determine whether this system prevented DFUs. The intervention and control groups were also trained in ulcer prevention and observed in follow-up at 6-month intervals for 24 months. RESULTS: 283 patients were recruited. In 85 137 observation days, DFUs arose in five patients in the control group (n = 143) and in no patient in the intervention group (n = 140). The primary outcome measure was the hazard ratio, which was calculated to be 0.015 (95% confidence interval [0; 19,717]; p = 0.25) after adjustment for age, sex, severity of neuropathy, and risk class. There were 239 alarms and 75 instructions to reduce weight-bearing on the foot. The subjects carried out the telemedical application on about 70% of the days of observation. Quality of life improved in both groups. CONCLUSION: The tele-health system used in this trial is practical and enables the early detection of morbidity. Likely explanations for the unexpectedly low ulceration rate in this trial (and, in turn, for the lack of statistical significance) include the availability of a training program and regular follow-up examinations to patients in both arms of the trial, along with lower mobility levels due to the COVID pandemic.

Structure-Based Design of α-Substituted Mercaptoacetamides as Inhibitors of the Virulence Factor LasB from Pseudomonas aeruginosa.

Antivirulence therapy has become a widely applicable method for fighting infections caused by multidrug-resistant bacteria. Among the many virulence factors produced by the Gram-negative bacterium Pseudomonas aeruginosa, elastase (LasB) stands out as an important target as it plays a pivotal role in the invasion of the host tissue and evasion of the immune response. In this work, we explored the recently reported LasB inhibitor class of α-benzyl-N-aryl mercaptoacetamides by exploiting the crystal structure of one of the compounds. Our exploration yielded inhibitors that maintained inhibitory activity, selectivity, and increased hydrophilicity. These inhibitors were found to reduce the pathogenicity of the bacteria and to maintain the integrity of lung and skin cells in the diseased state. Furthermore, two most promising compounds increased the survival rate of Galleria mellonella larvae treated with P. aeruginosa culture supernatant.

Substrate-Inspired Fragment Merging and Growing Affords Efficacious LasB Inhibitors.

Extracellular virulence factors have emerged as attractive targets in the current antimicrobial resistance crisis. The Gram-negative pathogen Pseudomonas aeruginosa secretes the virulence factor elastase B (LasB), which plays an important role in the infection process. Here, we report a sub-micromolar, non-peptidic, fragment-like inhibitor of LasB discovered by careful visual inspection of structural data. Inspired by the natural LasB substrate, the original fragment was successfully merged and grown. The optimized inhibitor is accessible via simple chemistry and retained selectivity with a substantial improvement in activity, which can be rationalized by the crystal structure of LasB in complex with the inhibitor. We also demonstrate an improved in vivo efficacy of the optimized hit in Galleria mellonella larvae, highlighting the significance of this class of compounds as promising drug candidates.

Structure-Activity Relationship and Mode-Of-Action Studies Highlight 1-(4-Biphenylylmethyl)-1H-imidazole-Derived Small Molecules as Potent CYP121 Inhibitors.

CYP121 of Mycobacterium tuberculosis (Mtb) is an essential target for the development of novel potent drugs against tuberculosis (TB). Besides known antifungal azoles, further compounds of the azole class were recently identified as CYP121 inhibitors with antimycobacterial activity. Herein, we report the screening of a similarity-oriented library based on the former hit compound, the evaluation of affinity toward CYP121, and activity against M. bovis BCG. The results enabled a comprehensive SAR study, which was extended through the synthesis of promising compounds and led to the identification of favorable features for affinity and/or activity and hit compounds with 2.7-fold improved potency. Mode of action studies show that the hit compounds inhibit substrate conversion and highlighted CYP121 as the main antimycobacterial target of our compounds. Exemplified complex crystal structures of CYP121 with three inhibitors reveal a common binding site. Engaging in both hydrophobic interactions as well as hydrogen bonding to the sixth iron ligand, our compounds block a solvent channel leading to the active site heme. Additionally, we report the first CYP inhibitors that are able to reduce the intracellular replication of M. bovis BCG in macrophages, emphasizing their potential as future drug candidates against TB.

Plantar temperatures in stance position: A comparative study with healthy volunteers and diabetes patients diagnosed with sensoric neuropathy.

BACKGROUND: Microcirculatory defects in diabetes are linked with neuropathy and the onset of diabetic foot syndrome. In this study we quantify pressure- and posture-dependent changes of plantar temperatures as a surrogate of tissue perfusion in healthy volunteers versus diabetes patients diagnosed with neuropathy in the absence of macroangiopathy. METHODS: Healthy volunteers (n = 31) as well as patients with diabetes diagnosed with severe polyneuropathy (n = 30) were enrolled in a clinical study to test for plantar temperature changes in the feet during extended episodes of standing. These lasted between 5 and 20 min each over 95 min, in between the participants were asked to take a seated position for 5 min and release the pressure from the feet. Major macroangiopathy was excluded before study enrolment. Custom-made insoles harbored temperature and pressure sensors positioned at eight preselected positions for recording. FINDINGS: In both subgroups a significant plantar temperature downshift occurred within 10 min of standing, which was especially detected during the initial 45 min of the study protocol. Comparisons between healthy volunteers and patients with diabetes revealed no differences in the magnitude of temperature downshifts during stance episodes. Pressure sensor recordings revealed that healthy volunteers intermittently released pressure during the longer stance episodes due to discomfort, whereas the patients with diabetes and polyneuropathy did not. INTERPRETATION: Our findings demonstrate a tight plantar temperature regulation following pressure exposure. In patients with diabetes and peripheral sensoric neuropathy the temperature drop is similar to healthy volunteers. Potentially, prolonged stance periods resulting in less perfused plantar tissue may remain unrecognized with polyneuropathy, whereas discomfort develops in healthy controls. FUNDING: The study was supported by EFRE Förderung der Europäischen Union und Landesmittel des Ministeriums für Wirtschaft, Wissenschaft und Digitalisierung Sachsen-Anhalt (Vorhabennummer: ZS/2016/05/78,615 and ZS/2018/12/95,325). JK and PRM were supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - project ID 97,850,925 - SFB854, AM by the Chinese Scholarship Council (CSC).

Study protocol for a randomized controlled trial to test for preventive effects of diabetic foot ulceration by telemedicine that includes sensor-equipped insoles combined with photo documentation.

BACKGROUND: Early detection of diabetic foot ulcerations (DFUs) can avoid or delay any progression into more severe stages, which may require limb amputation or lead to infectious sequelae and death. However, frequent clinical screening would be too intrusive and costly, and self-examination may be hampered by concomitant diseases and social disabilities. In addition, it requires professional knowledge and experience using specialized devices. Researchers reported that skin temperature monitoring could reduce the risk of DFUs in high-risk patients. The main research objects in this field are effective and convenient means of temperature measurement, accurate and reasonable early warning mechanisms, and timely and appropriate interventions. This trial aims to investigate the effectiveness of daily home-based foot temperature measurements in the prevention of DFUs with the aid of intelligent sensor-equipped insoles combined with photo documentation. METHODS/DESIGN: In this open-label, prospective, randomized, 24-month trial, 300 patients with diabetes mellitus (type 1 or 2) and severe diabetic peripheral neuropathy (vibration sensation ≤ 4/8), aged 18-85 years, will be recruited and assigned to control and intervention groups in a ratio of 1:1. Main inclusion criteria to be eligible for study participation encompass in particular risk group 2 or 3 for the development of DFUs using the diabetic foot risk classification system (as specified by the International Working Group on the Diabetic Feet [IWGDF]) and the ability to use a mobile phone. INTERVENTIONS: Participants in both groups will receive education about regular foot care at the beginning of the study (visit 0). In the intervention group, every patient will receive a pair of slippers with the inserted sensor-equipped insole as well as a smartphone with the corresponding smartphone application (Smart Prevent Diabetic Feet Application). The insole is a tool that records the temperature variabilities of the plantar foot. Patients will measure their foot temperature twice a day at home with a time interval > 4 h during the entire course of the study (24 months). The measured data will be initially analyzed and visualized, and further transferred to a remote server that allows the physician to perform specific interpretations. In case of temperature differences > 1.5 °C between left and right corresponding sites lasting > 32 h (assigned alarm level 4), the physician will start an intervention phase, which requires the patient to reduce daily activities and relax his feet for five days. At the same time, photo documentation is encouraged to be performed by the patient. Possibly, additional visits to a private doctor or clinical examinations will be arranged for the patient during this intervention period. OUTCOMES: The primary outcome is foot ulceration, evaluated by a physician, and occurring at any point during the study. DISCUSSION: This study addresses principal aspects in the prevention of DFUs. First, the sensor-equipped insole will be evaluated for daily performance in home-based measurements of foot temperatures. Second, a telemedicine structure is tested that evaluates sensor data automatically and proposes suitable intervention measures under the supervision of a physician. Third, predictive models for DFUs will be built using the collected sensor data allowing for interpretations, which in the future may support medical care providers. TRIAL REGISTRATION: German Clinical Trials Register (DRKS), DRKS00013798 . Registered on 18 January 2018.

Tackling Pseudomonas aeruginosa Virulence by a Hydroxamic Acid-Based LasB Inhibitor.

In search of novel antibiotics to combat the challenging spread of resistant pathogens, bacterial proteases represent promising targets for pathoblocker development. A common motif for protease inhibitors is the hydroxamic acid function, yet this group has often been related to unspecific inhibition of various metalloproteases. In this work, the inhibition of LasB, a harmful zinc metalloprotease secreted by Pseudomonas aeruginosa, through a hydroxamate derivative is described. The present inhibitor was developed based on a recently reported, highly selective thiol scaffold. Using X-ray crystallography, the lack of inhibition of a range of human matrix metalloproteases could be attributed to a distinct binding mode sparing the S1' pocket. The inhibitor was shown to restore the effect of the antimicrobial peptide LL-37, decrease the formation of P. aeruginosa biofilm and, for the first time for a LasB inhibitor, reduce the release of extracellular DNA. Hence, it is capable of disrupting several important bacterial resistance mechanisms. These results highlight the potential of protease inhibitors to fight bacterial infections and point out the possibility to achieve selective inhibition even with a strong zinc anchor.