Adsorption of malic acid at the hydroxyapatite/aqueous NaCl solution interface

The aim of the study was the basic incidence on the phenomenon of adsorption that occurs at the hydroxyapatite/malic acid interface, leading to a change in the surface properties of hydroxyapatite, Analytical methods used in the research: X-ray diffraction (XRD) as well as by the, adsorption–desorption of nitrogen (ASAP), potentiometric titration. The specific adsorption of malic acid ions at the hydroxyapatite interface was investigated by means of the radioisotope method. The zeta potential of hydroxyapatite dispersions was determined by electrophoresis with Zetasizer Nano ZS90 by Malvern. The particle sizes of hydroxyapatite samples were analyzed using Masteriszer 2000 Malvern. Studies on the kinetics of malic acid on hydroxyapatite from a solution with an initial concentration of 1 mmol/dm3 have shown that the adsorption process is initially fast, followed by a slow adsorption step. An increase in the pH of the solution causes a decrease in the malic acid adsorption as a result of competition with hydroxyl ions. The presence of adsorbed malic acid was confirmed by the FTIR measurements. The effect of malic acid adsorption on the zeta potential and particle size distribution of hydroxyapatite in the NaCl solution was investigated.

Adsorption of the Tartrate Ions in the Hydroxyapatite/Aqueous Solution of NaCl System

The research on the interaction of tartrate ions with the surface of hydroskyapatite was presented, including the measurements of the kinetics of tartrate ion adsorption and tartrate ion adsorption as a function of pH. The adsorption of tartrate ions was calculated from the loss of tartrate concentration in the solution as measured by a radioisotope method using C-14 labeled tartaric acid. In order to explain the mechanism of interaction of tartrate ions with hydroxyapatite, supplementary measurements were carried out, i.e., potentiometric measurements of the balance of released/consumed ions in the hydroxyapatite/electrolyte solution system, zeta potential measurements, FTIR spectrophotometric measurements and the hydroxyapatite crystal structure and particle size distribution were characterized. It was found that the adsorption of tartrate ions occurs as a result of the exchange of these ions with hydroxyl, phosphate and carbonate ions. Replacing the ions with the abovementioned tartrate ions leads to the appearance of a negative charge on the surface of the hydroxapatite. On the basis of XRD study and particle size distribution, a decrease in the size of crystallites and the diameter of hydroxyapatite particles in contact with a solution of 0.001 mol/dm3 of tartaric acid was found.

ALGAE AND CYANOBACTERIA AS FACTORS IN THE FORMATION OF THE POOL OF DISSOLVED ORGANIC SUBSTANCES AND WATER QUALITY IN THE RESERVOIR DURING CELL DEATH

Using the radioisotope method, new quantitative characteristics of the role of phytoplankton in the formation of the pool of dissolved organic substances (ROS) in the freshwater ecosystem were obtained. The destruction of dead phytoplankton is carried out within one week. In natural reservoirs, detritus settles at a rate of about one meter per day. In deep reservoirs, most of the MOAT is released in the water column rich in oxygen, where it is destroyed by bacterioplankton. In shallow reservoirs (such as fish ponds), detritus particles do not have time to decompose in the water column. Their further destruction is carried out at the bottom of the reservoir when there is a lack of oxygen, which leads to overseas phenomena.

P738The restoration effect of metformin on the beta-adrenergic signaling, amp-activated kinase and akt-kinase in the myocardium of diabetic rats

Background The type 2 diabetic mellitus (DM2) induces the myocardial dysfunctions, the impairment of beta-adrenergic regulations and the alterations of energy homeostasis and apoptotic processes in the myocardium are the main causes of diabetic cardiomyopathy. Metformin (MF) is a first-line drug for management of DM2. However, MF effects on the adrenergic signaling, the cell metabolism and survival in the cardiomyocytes are still poorly understood. Purpose To study MF effects on the beta-adrenergic signaling in myocardial membranes and on the expression and activity of beta1- and beta3-adrenergic receptors (ARs), AMP-activated kinase (AMPK), Akt-kinase and the pro- (Bax) and anti-apoptotic (Bcl-2) proteins in the myocardium of diabetic rats. Methods In male rats, DM2 was induced by high-fat/high-carbohydrate diet (three months) and by a single treatment with low-dose streptozotocin. Diabetic rats were treated with MF at two doses, 100 and 200 mg/kg/day, during 28 days. The stimulating effects of beta-AR agonists on adenylyl cyclase (AC) activity in the cardiac membranes were studied by radioisotope method. The gene expression was estimated by qPCR, and the protein amount and their activity were studied by Western blotting. Four groups of animals, such as control (C, n=12), DM2 (D, n=12), and DM2 treated with MF at the doses 100 (D100, n=9) and 200 mg/kg/day (D200, n=9) were investigated. Results MF restores the stimulating AC effect of beta1-agonists, the beta1-AR gene expression and the beta1/beta3-ARs ratio, all reduced in DM2, and restoration effect of MF in Groups D100 and D200 was similar. Meanwhile, in Group D200, but not in Group D100, the AC effect of beta3-agonists and the expression of beta3-AR, both increased in DM2, returns to the control values. In diabetic myocardium, MF restores the AMPK and Akt-kinase activities, reduced in DM2, and it is illustrated by the increased phosphorylation of AMPK by Thr172 and Akt-kinase by Ser473 and Thr308. Despite the fact that MF at a dose of 200 mg/kg/day to a greater extent, as compared to a dose of 100 mg/kg/day, increases the “stimulating” Thr172-phosphorylation, but at the same time it also enhances the “inhibiting” Ser491-phosphorylation of AMPK, decreasing the resulting stimulation of AMPK. In Groups D100 and D200 the Bax/Bcl-2 ratio, significantly increased in DM2, is reduced. This data indicates the weakening of apoptosis in cardiomyocytes in DM2. Conclusion The four-week MF treatment improves the myocardial beta-adrenergic signaling, normalizing the expression and activity of beta1- and beta3-ARs, restores the activity of AMPK and Akt-kinase, the effector components of the signaling cascades responsible for cell survival and metabolism, and normalizes the expression of apoptotic factors. Thus, the cardioprotective MF effect is largely due to the improved myocardial signaling, including the beta1-AR, AMPK and Akt-kinase signaling pathways. Acknowledgement/Funding This work was supported by the Russian Science Foundation (No. 17-75-30052) and partially by the Government Assignment (AAAA-A18-118012290427-7).

Neck dissections based on sentinel lymph node navigation versus elective neck dissections in early oral cancers: A randomized, multicenter, non-inferiority trial.

6007 Background: The objective of the study is to evaluate the non-Inferiority of survival, the superiority of postoperative disability, and the complication of the neck in neck dissections based on sentinel lymph node navigation in early oral cancer patients, compared with standard selective neck dissections. Methods: This study was a randomized, multicenter, non-inferiority trial at 16 institutions in Japan. Eligibility criteria included histologically confirmed squamous cell carcinoma in the oral cavity; clinical categories T1 and T2, N0M0 by UICC TNM classification 7th edition, clinical depth of invasion (DOI) of T1 was over 4mm (defined as late T1); previously untreated; age at least 18 years; and written informed consent. We randomly assigned patients (1:1) to receive either sentinel lymph node biopsy (SNB) or standard selective neck dissections (ND) with stratification of T category (lateT1 vs T2) and subsite (tongue vs others). The primary endpoint was 3-year overall survival with a non-inferiority margin of 12%. Sentinel nodes (SNs) were detected using radioisotope method and examined with multislice frozen section analysis intraoperatively, following HE and cytokeratin stain for a final postoperative diagnosis. Patients with positive SNs had neck dissections in a one-stage or back up procedure. Results: Between November 2011 and January 2016, 271 patients were enrolled and randomized to SNB group (134 patients) and ND group (137 patients) with a median follow-up of 37 months (IQR 36-39). Pathological positive nodal status was 34% (46/132) in SNB group and 26% (34/133) in ND group (Chi-Square p = 0.10). 3-year overall survival in SNB group was 89% (95%CI 82-93%), which was non-inferior to that in ND group (86%, 95%CI 79-91%). 3-year relapse-free survival was 80% (95%CI 72-86%) in SNB group and 81% (95%CI 73-87%) in ND group. Arm abduction of postoperative 1 and 3 months in ND group was disturbed significantly compared with SNB group. Conclusions: SNB navigated ND could replace elective ND without survival disadvantage and reduce postoperative disability of the neck in patients with early oral cancer. Clinical trial information: 000006510.

POSSIBILITIES OF DETECTION OF SENTINEL LYMPH NODES IN ENDOMETRIAL CANCER BY RADIOISOTOPE AND FLUORESCENT (ICG) METHODS

On the basis of the Departments of Oncogynecology and Radiology of the N.N. Petrov Research Institute of Oncology there was performed a comparative analysis of the results of detection of the sentinel lymph node using a fluorescent method with Indocyanine Green (ICG) and a radioisotope method with 99m-labeled colloidal radiopharmaceutical in endometrial cancer patients undergoing laparoscopic hysterectomy with lymphadenectomy from June 2016 to December 2016. The study included 19 patients with early endometrial cancer. Specificity and sensitivity of methods of radiation diagnostics (ultrasound and MRI) in the detection of metastatic involvement of pelvic lymph nodes are also presented.