Stanislawa Sabalinska

Accuracy and Precision of Selected Wound Area Measurement Methods in Diabetic Foot Ulceration

AIM The present study assesses precision and accuracy of four selected methods of wound area measurements in diabetic foot wounds. MATERIALS AND METHODS The areas of 16 wound shapes were measured using linear measurement with elliptical estimation (Elliptical method), using the Visitrak™ (Smith & Nephew, London, United Kingdom) device, the SilhouetteMobile™ device (ARANZ Medical Ltd., Christchurch, New Zealand), and the TeleDiaFoS system (Nalecz Institute of Biocybernetics and Biomedical Engineering, Warsaw, Poland). The actual area of a wound shape was determined with a tested scanner and specifically developed software. Accuracy of the area measurement method was assessed by the relative error (RE), whereas precision was assessed by the coefficient of variation (CV). RESULTS The overall absolute REs were 13.3%, 6.8%, 2.1%, and 2.3% for the Elliptical method, the Visitrak device, the TeleDiaFoS system, and the SilhouetteMobile device, respectively. The accuracy of the Visitrak device was remarkably reduced for wound areas smaller than 2 cm². The overall CVs were 6.0%, 6.3%, 1.6%, and 3.1% for the Elliptical method, the Visitrak device, the TeleDiaFoS system, and the SilhouetteMobile device, respectively. The precision of the Visitrak device was revealed to be remarkably lower for small wounds (<2 cm²). CONCLUSIONS The Elliptical method gives overestimation up to 33%; thus, it should not be used in applications where the actual wound area is an important parameter (like the prediction of wound healing). The TeleDiaFoS system and the SilhouetteMobile device showed the best accuracy of all used methods; however, the precision of the TeleDiaFoS system was revealed to be higher than the precision of the SilhouetteMobile device. The accuracy and the precision of the Visitrak device are significantly reduced for wounds smaller than 2 cm².

Impact of convective transport on dialyzer clearance

Abstract The results of predictions of three mathematical models used to describe the impact of convective flow on dialyzer clearance are presented. These models are based on the ordinary differential equations, which describe changes of solute concentration and solute and fluid flows along the module length. One of the models takes into consideration the existence of the boundary layers on both sides of the membrane wall, by including in the equations two parameters kB and kD, which describe mass transport coefficients in blood and dialysate, respectively. In the second model, the boundary layers are included in one lumped membrane permeability parameter. The diffusive membrane permeability was calculated from pure diffusive clearance, which was taken from experimental results. In the third model, a linear dependence of transmittance coefficient and ultrafiltration flow was proposed. The theoretical results were compared with data obtained in experiments carried out in vitro with four types of high-flux hollow-fiber dialyzers. The comparisons demonstrate that the first two models are of similar accuracy and the third model is not suitable for small solutes.

A new imaging and data transmitting device for telemonitoring of diabetic foot syndrome patients.

BACKGROUND Proper healing of ulcers and wounds on the feet of diabetes patients is important in order to prevent amputation. If the wound area reduction during the first 4 weeks of the treatment is not 40% or more, reevaluation of the treatment is necessary. The wound area evaluation is not complicated when the patient stays at a hospital, but when he or she goes home the physician does not have a tool allowing monitoring of the wound area. METHODS AND RESULTS The aim of the present article is to present a new device able to take a wound picture and send it automatically to the database. This device, called the Patients Module (PM), is also able to download data from the memories of blood pressure and blood glucose meters and send the data to the database. The PM is able to operate within the TeleDiaFoS system (developed earlier in collaboration with the Department and Clinic of Gastroenterology and Metabolic Diseases, Medical University of Warsaw, Warsaw, Poland) aimed at monitoring of treatment of patients with diabetic foot syndrome. The PM was tested on 10 type 2 diabetes patients during a 3-month period. CONCLUSIONS The study revealed that the PM can be used as a home telemonitoring device, and the analysis of the data sent from patients home enables the assessment of wound healing progress, giving the physician the possibility for earlier change of the treatment if the wound area reduction is not satisfactory.

Polypropylene hollow fiber for cells isolation: methods for evaluation of diffusive transport and quality of cells encapsulation.

Formulation of membrane properties is important prior the successful implantation of encapsulated cells producing therapeutically relevant compounds. The purpose of our study was to specify the methods allowing preliminary evaluation of hollow fibers (HF) chosen for immunoisolation. We have selected as estimates (1) diffusive permeability for small and large solutes, and HF cut off (in vitro), (2) histological evaluation of tissue overgrowth after sc. implantation into mice. It was found that diffusive coefficients were linearly dependent on the particle diameter except that of albumin (2–3 times higher than theoretically estimated). This discrepancy imply that for certain particles the interaction with membrane material may be significant. The histological evaluation showed that siliconized HF implanted for 105 days were accepted (there was thin fibrotic layer on the external surface of the HF, no surrounding haemopoietic cells were found). It is concluded that proposed methods for preliminary evaluation of hollow fibers chosen for immunoisolation seems to be reliable and suitable for testing diffusive permeability of each relevant cell product.

Growth factors and their receptors derived from human amniotic cells in vitro.

In vitro studies have shown that amnion-produced growth factors participated in angiogenesis, re-epithelialization, and immunomodulation. The aim of our study was to investigate the growth factors and receptors produced by human amnion tissue and amniotic cells. Human amnions (hAM) were isolated, and amnion circles were dissected for in vitro analysis. Some amnion fragments were digested by the use of different methods to obtain two cell fractions, which were analysed for mesenchymal and epithelial cell markers. Amniotic circles and human amniotic cell fractions were cultured in a protein-free medium. Proteins secreted into the culture medium were analysed with a human growth factor antibody array. Conditioned culture media were added to human umbilical vein epithelial cells (HUVECs) to test for stimulation of migration (scratch test) and proliferation (Ki67 expression). Fraction 1 cells expressed both cytokeratin and mesenchymal cell markers which indicated that it was composed of a mixture of human amnion epithelial cells (hAECs) and mesenchymal stromal cells (hAMSCs). Fraction 2 cells mainly expressed cytokeratin and, therefore, were designed as hAECs. Secretion of proteins by the cultured cells increased with time. The hAM cultures secreted EGF-R, IGF, and IGFBP-2,-3 and -6; Cell Fraction 1 secreted NT-4, whereas Cell Fraction 2 secreted G-CSF, M-CSF, and PDGF. Conditioned media of hAM cultures stimulated HUVECs migration. We have showed for the first time that human amnions and amniotic cells secreted IGFBP-6, MCSF-R, PDGF-AB, FGF-6, IGFBP-4, NT-4, and VEGF-R3. We found that Cell Fraction 1, Cell Fraction 2, and the whole amnion secreted different proteins, possibly due to different proportions of amnion-derived cells and different cell-cell interactions. The hAM cell factors remained functional in vitro and induced intensified migration of HUVECs. The growth factors and receptors found in amnion or amniotic cell media might be used for regenerative medicine.

Wound Area Measurement with Digital Planimetry: Improved Accuracy and Precision with Calibration Based on 2 Rulers

Introduction In the treatment of chronic wounds the wound surface area change over time is useful parameter in assessment of the applied therapy plan. The more precise the method of wound area measurement the earlier may be identified and changed inappropriate treatment plan. Digital planimetry may be used in wound area measurement and therapy assessment when it is properly used, but the common problem is the camera lens orientation during the taking of a picture. The camera lens axis should be perpendicular to the wound plane, and if it is not, the measured area differ from the true area. Results Current study shows that the use of 2 rulers placed in parallel below and above the wound for the calibration increases on average 3.8 times the precision of area measurement in comparison to the measurement with one ruler used for calibration. The proposed procedure of calibration increases also 4 times accuracy of area measurement. It was also showed that wound area range and camera type do not influence the precision of area measurement with digital planimetry based on two ruler calibration, however the measurements based on smartphone camera were significantly less accurate than these based on D-SLR or compact cameras. Area measurement on flat surface was more precise with the digital planimetry with 2 rulers than performed with the Visitrak device, the Silhouette Mobile device or the AreaMe software-based method. Conclusion The calibration in digital planimetry with using 2 rulers remarkably increases precision and accuracy of measurement and therefore should be recommended instead of calibration based on single ruler.

Microdialysis monitoring of glucose, lactate, glycerol, and pyruvate in patients with diabetic ketoacidosis.

Purpose The objective was to assess glucose, lactate, glycerol, and pyruvate concentrations in the interstitial fluid of the adipose tissue as well as the glucose relative recovery coefficient in reference to capillary blood (RC) during the first two days of the standard treatment of diabetic ketoacidosis (DKA) in patients with type 1 and type 2 diabetes. Materials and Methods The study group consisted of 19 patients (12 with type 1 diabetes and 7 with type 2 diabetes). The metabolic state of the patients was monitored using the microdialysis technique. The analysis of variance was used to investigate whether the type of diabetes and the duration of treatment influenced the assessed parameters. Results Concentrations of all the monitored components were stable after the initial 12 h of treatment. Glucose concentration was higher and concentrations of all the other components were lower (p<0.0001) in patients with type 1 diabetes than in patients with type 2 diabetes. Significantly higher RC was observed in patients with type 1 diabetes during the initial 12 h. Conclusions The results suggest that the standard treatment of DKA is effective in stabilizing a concentration of the studied metabolic components in the interstitial fluid in patients with type 1 and type 2 diabetes despite differences in the glucose concentration at the beginning of the treatment.

Response of human normal and leukemia cells to factors released by amnion fragments in vitro

Amnion is a membrane surrounding the embryo/fetus which determine growth factors and interleukins with angiogenic, immunogenic, and anti-inflammatory properties. The aim of the present study was to investigate the effects of conditioned culture medium from 24-h cultures of human amnion (hAM CCM) on migration and proliferation of human umbilical vein endothelial primary cells (HUVECs), freshly isolated bone marrow mononuclear cells (BM MNCs), and Jurkat leukemia cell line. Amnion membrane was freshly isolated from healthy placenta and its fragments cultured in vitro to produce hAM CCM. Members of the IGFBP protein family made up one third of all assayed proteins present in the hAM medium. The hAM CCM did not affect the proliferation rate of HUVECs or MNCs, but we observed more intensive migration of those cells, and lower expression of CD31 surface antigen on HUVECs as compared to control cultures. In contrast, Jurkat cells did not respond to hAM CCM treatment by proliferation or mobility change. The conditioned medium from 24-h cultures of human amnion is easy to obtain and is a convenient source of various growth and other factors that may be useful in practical medicine.

An Analysis of the Hemoglobin Glycation Rate in the A1C-Derived Average Glucose Study Population Applying a Monte Carlo Method

Diabetes is a huge and growing problem, and the costs to society are consistently increasing. The glycated hemoglobin A1c (HbA1c) concentration is a frequently used marker of the metabolic control. In 2008 the results of the A1c-Derived Average Glucose (ADAG) Study were reported establishing a linear relationship between HbA1c and the preceding glycemia. The aim of this study was to analyze the overall hemoglobin glycation rate constant (k) in the ADAG population applying a Monte Carlo method. We reproduced the distribution of HbA1c and plasma glucose concentrations in the ADAG population and we obtained an estimate of k equal to 1.239 ± 0.175×10− 9 L/(mmol s) assuming that red blood cells’ (RBCs) life span was equal to 120 days. The k value estimated in this study is in a good agreement with values of this parameter reported earlier. It was also demonstrated that a normal distribution of RBCs’ life span with the standard deviation of 14 days is sufficient to explain the inter-subject variability of the hemoglobin glycation rate. The obtained distribution of RBCs’ life spans is even less scattered around the mean than previously reported distributions for healthy individuals and for patients with diabetes. However, an assumption that k is the same for all the individuals implies a positive correlation of RBCs’ life span and HbA1c concentration, which was inconsistent with earlier reports. This result suggests that the hemoglobin glycation rate might increase with a deterioration of the metabolic control.

A Comparison of Three Techniques for Wound Area Measurement

Reduction of wound surface area has been identified as one of the important parameter of the applied therapy assessment in diabetic foot ulceration. There are some methods of wound area measurement and this paper presents the comparison of the Visitrak device, the Silhouette Mobile device and the TeleDiaFoS system. All devices were designed for such a measurements and are based on digital planimetry. Sixteen wound shapes made of adhesive film and prepared based on pictures of actual diabetic foot wounds were placed on feet of 10 volunteers and measured with all devices. The Pearson’s r correlation coefficient and linear regression equation were calculated between each pair of methods. All methods are highly correlated with r equal to at least 0.97 (p<0.0001). The linear regression equations were calculated for all data (0 - 17 cm2) and in two sub-ranges: 0-2 cm2 and 2-17 cm2. These equations may be used for recalculation of results from one method into another. The use of appropriate equation according to range of value to be recalculated will provide more accurate result.