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It is reported that the interaction of hydrogen peroxide and sodium bicarbonate solution with thick sputum, mucus, pus and blood clots leads to their rapid transformation into a fluffy oxygenated foam. This mechanism of action allows repurposing hydrogen peroxide from antiseptic to expectorant and oxygen forming antihypoxant, which can find application for recanalization of airways and increasing blood oxygenation in acute respiratory syndrome. It is reported that acute respiratory distress syndrome in COVID-19 can be caused by excessive accumulation of thick sputum, mucus and pus in the airways, which complicates intra-pulmonary oxygenation of blood, causes hypoxia and causes death, since there are no drugs for urgent recanalization of the airways today. At the same time, the first evidence emerged that alkaline hydrogen peroxide solution can claim to be an inhaled expectorant and oxygen-producing drug for urgent recanalization of the airways when they are blocked by mucus, sputum, pus, blood and other colloidal fluid containing the enzyme catalase.

It has been established that warm alkaline solutions of hydrogen peroxide with local interaction with thick pus, mucus, sputum and blood have local pyolytic, mucolytic and hemolytic effects. It was found that the dissolving effect is associated with the alkaline properties of the drug, which are provided by sodium bicarbonate. Sodium bicarbonate provides the process of alkaline saponification of proteins and protein-lipid complexes. It is shown that hydrogen peroxide intensively decomposes into water and oxygen gas under the action of the catalase enzyme. In turn, catalase is always present in blood, mucus, sputum, pus, fibrous and serous fluid. At the same time, the released oxygen forms gas bubbles that literally tear apart biological masses during cold boiling and turn them into fluffy white foam. At the same time, the appearance of oxygen in an alkaline environment ensures the process of discoloration of biological pigments, such as hemoglobin and its color metabolites. The indicated pharmacological effect of a warm alkaline solution of hydrogen peroxide at local interaction is proposed to be used for the treatment of purulent diseases, thrombosis, bruising and hematomas. The technologies of using the drug for urgent restoration of breathing in obstructive purulent bronchitis, for urgent discoloration of the skin and nail plate with bruising and hematoma, as well as for urgent and safe peeling of a bloody bandage from a wound are listed.

(1) Purpose: Recent studies indicate that advanced imaging parameters such as prostate PSMA tumor volume may have a value in predicting response to treatment of castration-resistant prostate cancer patients. In this study, we examine whether a relationship can be found between advanced imaging parameters such as prostate PSMA-TV and the presence of metastatic disease in newly diagnosed prostate cancer patients undergoing PSMA-PET/CT for staging purposes; (2) Methods: We retrospectively analyzed PET/CT studies of 91 patients with newly diagnosed prostate cancer. Prostate PSMA-TV was measured using the MIRADA-XD software. PET/CT results were recorded, as well as additional clinical parameters such as the Gleason score, etc.; (3) Results: Prostate PSMA-TV measurements were found to be able to significantly differentiate metastatic from the non-metastatic patient groups (13.7 vs. 5.5, p-value < 0.05). Overall, 54% percent of patients with levels of over 8.1 PSMA-TV had metastatic lesions found on their PSMA-PET/CT. A model based on this cutoff attained a sensitivity of 80%, a specificity of 68.3%, and a negative predictive value of 93.5% for identifying metastatic disease. Another bin model was found statistically capable of assessing the likelihood of the presence of metastatic disease with a p-value of 0.001; (4) Conclusions: Prostate PSMA-TV measurement has the potential to predict the presence of metastatic disease at staging and thus may impact further treatment decision and patient management.

BackgroundThe iron-based phosphate binder (PB), sucroferric oxyhydroxide (SFOH), demonstrated its effectiveness for lowering serum phosphate levels, with low daily pill burden, in clinical trials of dialysis patients with hyperphosphatemia. This retrospective database analysis evaluated the real-world effectiveness of SFOH for controlling serum phosphate in European hemodialysis patients.MethodsDe-identified patient data were extracted from a clinical database (EuCliD®) for adult hemodialysis patients from France, Italy, Portugal, Russia and Spain who were newly prescribed SFOH for up to 1 year as part of routine clinical care. Serum phosphate and pill burden were compared between baseline (3-month period before starting SFOH) and four consecutive quarterly periods of SFOH therapy (Q1−Q4; 12 months) in the overall cohort and three subgroups: PB-naïve patients treated with SFOH monotherapy (mSFOH), and PB-pretreated patients who were either switched to SFOH monotherapy (PB → mSFOH), or received SFOH in addition to another PB (PB + SFOH).Results1096 hemodialysis patients (mean age: 60.6 years; 65.8% male) were analyzed, including 796, 188 and 53 patients in, respectively, the PB + SFOH, mSFOH, and PB → mSFOH groups. In the overall cohort, serum phosphate decreased significantly from 1.88 mmol/L at baseline to 1.77–1.69 mmol/L during Q1–Q4, and the proportion of patients achieving serum phosphate ≤1.78 mmol/L increased from 41.3% at baseline to 56.2–62.7% during SFOH treatment. Mean PB pill burden decreased from 6.3 pills/day at baseline to 5.0–5.3 pills/day during Q1–Q4. The subgroup analysis found the proportion of patients achieving serum phosphate ≤1.78 mmol/L increased significantly from baseline during SFOH treatment in the PB + SFOH group (from 38.1% up to 60.9% [Q2]) and the mSFOH group (from 49.5% up to 75.2% [Q2]), but there were no significant changes in the PB → mSFOH group. For the PB + SFOH group, serum phosphate reductions were achieved with a similar number of PB pills prescribed at baseline prior to SFOH treatment (6.5 vs 6.2 pills/day at Q4). SFOH daily pill burden was low across all 3 subgroups (2.1–2.8 pills/day).ConclusionIn this real-world study of European hemodialysis patients, prescription of SFOH as monotherapy to PB-naïve patients, or in addition to existing PB therapy, was associated with significant improvements in serum phosphate control and a low daily pill burden.

BACKGROUND AND AIMS Haemodiafiltration on-line (HDF-ol), an effective mode of replacement therapy for stage 5 chronic kidney disease (CKD 5D), cannot be considered sufficiently studied in terms of its effect on the outcomes. Our main aim was to identify a possible association between individual anthropometric, laboratory data and parameters of the prescribed treatment regimen with the best survival rate when using the HDF-ol mode. METHOD A retrospective1 year analysis of the EuCliD database of 9986 patients treated with HDF-ol in 27 Fresenius Medical Care centres in Russia was carried out. All patients got post-dilution HDF-ol procedures at least 3 times a week, for at least 12 h a week with Kt/V at least 1.4. Data on alive (9616) and deceased (370) patients were compared by gender, age, treatment experience, body weight (BW), body mass index (BMI), body surface area (BSA), total body water volume (TBW), volume of urea distribution (V Urea BCM), presence of diabetes mellitus (DM), ischemic heart disease (CHD), chronic heart failure (CHF), as well as parameters of the procedure: effective weekly dialysis time, Kt/V, effective infusion volume (EIV) and effective convection volume (ECV). RESULTS Differences in groups were found only for a part of parameters (Table 1). CONCLUSION Association of risk of death in patients with CKD 5D treated with HDF-ol included male gender, older age, concomitant diseases (CHD, CHF, DM), lower BW and BMI, shorter effective weekly dialysis time, lower values of EIV and ECV, Kt/V, higher values of hypercalcemia, hypoalbuminemia, lower haemoglobin levels, higher levels of b2-microglobulin and CRP. Such indicators as TBW, VUrea BCM, BSA and the length of treatment on dialysis did not reached statistical significance when comparing alivе and deceased patients.

Relevance: The train drivers are responsible for the safety of transported people and goods. Therefore, medical monitoring of their state of health is an integral part of ensuring the safety of railway traffic.Purpose: to study the possibilities of using a pulsogram for analyzing the parameters of heart rate variability during pre-trip health examination of members of train crews.Materials and methods: 183 male train crew members (106 engine train drivers, 77 train drivers’ assistants) were examined; the average age was 37.7 ± 9.4 years. ECG and pulsogram were measured simultaneously, and heart rate variability was analyzed.Results: A high degree of coincidence of mean values and variances of heart rate variability parameters, calculated on the basis of ECG (electrocardiogram) and pulsogram, was found. A high degree of reliable positive correlation was established between these parameters. Significant differences in the parameters of heart rate variability were revealed between the members of train crews who underwent and those who did not undergo the first-time pre-trip medical examination.Conclusion: Measurements of heart rate variability parameters based on the pulsogram can be used to solve a number of urgent problems of pre-trip medical examination of members of train crews.

Alexandra Igrunkova,1,2 Alexey Fayzullin,1,2 Semyon Churbanov,1 Polina Shevchenko,1 Natalia Serejnikova,1,2 Natalia Chepelova,1,2 Dmitry Pahomov,3 Ekaterina Blinova,4 Karen Mikaelyan,1 Victoria Zaborova,5,6 Konstantin Gurevich,7 Aleksandr Urakov,8,9 Anatoly Vanin,1 Peter Timashev,1,2,10 Anatoly Shekhter1 1Institute for Regenerative Medicine, Sechenov First Moscow State Medical University, Moscow, Russian Federation; 2World-Class Research Center “Digital Biodesign and Personalized Healthcare”, Sechenov First Moscow State Medical University, Moscow, Russian Federation; 3Department of Operative Surgery and Topographic Anatomy, Sechenov First Moscow State Medical University, Moscow, Russian Federation; 4Department of Faculty Surgery, Ogarev Mordovia State University, Saransk, Republic of Mordovia, Russian Federation; 5Institute of Clinical Medicine, Sechenov First Moscow State Medical University, Moscow, Russian Federation; 6Laboratory of Sports Adaptology, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russian Federation; 7UNESCO Chair “Healthy life style for sustainable development”, Moscow State University of Medicine and Dentistry, Moscow, Russian Federation; 8Department of General and Clinical Pharmacology, Izhevsk State Medical Academy, Izhevsk City, Udmurt Republic, Russian Federation; 9Department of Modeling and Synthesis of Technological Processes, Institute of Applied Mechanics, Udmurt Federal Research Center of the Ural Branch of the Russian Academy of Sciences, Izhevsk City, Udmurt Republic, Russian Federation; 10Department of Chemistry, Lomonosov Moscow State University, Moscow, Russian FederationCorrespondence: Aleksandr Urakov, Department of General and Clinical Pharmacology, Izhevsk State Medical Academy, Kommunarov str., 281, Izhevsk City, Udmurt Republic, 426034, Russian Federation, Tel +011 79127600939, Email urakoval@live.ruBackground: Ditrosyl iron complexes (DNIC) are endogenous donors of nitric oxide. The possibility of their application to stimulate regeneration has been studied for more than 15 years. However, the most effective dose and form of delivery have not yet been determined.Purpose: The aim of this research was to develop a spray form of DNIC that accelerates wound healing.Methods: We prepared a series of DNIC sprays with spray dosages of 10, 50 and 100 μg. We modelled full-thickness skin wounds in 24 Wistar rats and treated them with distilled water (n = 6), 10 (n = 6), 50 (n = 6) and 100 μg (n = 6) for three post-operative days. On the fourth day, the excised wound tissues were studied by morphological, immunohistochemical and morphometric methods.Results: We demonstrated that 50 μg of DNIC spray had the most beneficial effect on wound healing: the thickness of the granulation tissue layer was 140% higher, vimentin positive fibroblasts predominated and the intensity of inflammation was significantly lower than in the control. There was a dose-dependent decrease in the functional activity of mast cells in the experimental groups compared to the control.Conclusion: DNIC spray is a potential effective dosage form for the treatment of large-area skin lesions.Graphical Abstract: Keywords: wound, infection, drug, resistance, research and development, nitric oxide, spray, healing

The purpose of this investigation was to assess the acute effects of partial range of motion (pROM) exercises, on the accuracy of soccer penalty kicks on goal. This method limits the joint from moving through the complete length of a motion, creates an occlusion effect, and thus causes the type 1 muscle fibers to work anaerobically. Thirty-six soccer players, with 5-8 years of soccer playing experience, were pretested for accuracy then retested ( rtt = 0.92 ) and divided into random groups from the Associação Banco do Brasil Futebol Clube—Group A, Paraná Futebol Clube—Group P, and Coritiba Futebol Clube—Group C. Groups were composed of 12 people performing full range of motion (fROM) exercises or pROM exercises. Both groups performed 5 sets of back squats at 50% of body weight in sets of 40 seconds with metronome tempo of 56 bpm for an average of 10-12 repetitions per 40-second set. Blood samples were collected post-warm-up, after the 3rd set, and following the 5th set for both groups, within 3–5 minutes of cessation of exercise. Athletes performing fROM exercises showed increased blood lactate from 2.69 ± 0.2 to 4.0 ± 1.2 mmol/L ( p < 0.05 ), and in pROM, blood lactate increased from 2.48 ± 0.42 to 10.29 ± 1.3 mmol/L ( p < 0.001 ). In fROM, accuracy decreased from 42.96 ± 13.39 % to 41.37 ± 17.25 % ( p > 0.1 ), a slight decrease, while in the pROM groups, accuracy decreased from 45.42 ± 14.93 % to 24.53 ± 10.2 % ( p < 0.001 ). The calculations demonstrating average percentages of accuracy are presented in the tables. These findings support that pROM exercises significantly increase blood lactate resulting in a reduction in soccer kick accuracy. This decrease in accuracy directly correlates to the accumulation of lactic acid and hydrogen ions (H+) and demonstrates that pROM strength training should not be utilized prior to a sport-specific session in order to avoid interference with the development of special skills.

Background and Aims This retrospective analysis of data from the European Clinical Database (EuCliD®) evaluated changes in iron-related parameters and use of concomitant anti-anaemic therapies in European haemodialysis (HD) patients treated with sucroferric oxyhydroxide (SFOH). Previous Phase 3 clinical studies and non-clinical studies have indicated that there is minimal iron absorption from SFOH. This study aimed to evaluate the changes in iron-related parameters among patients treated with SFOH in the real-world setting. Method De-identified patient data were extracted from a clinical database (EuCliD®) for adult HD patients newly prescribed SFOH routinely for up to 1 year (1 Jan 2015–1 Jan 2019). Levels of serum ferritin, transferrin saturation (TSAT) and haemoglobin were compared between baseline (BL; 3-month period before starting SFOH) and each quarterly period in the year after starting SFOH treatment (Q1–Q4). Proportions of patients receiving intravenous (IV) iron and erythropoiesis-stimulating agent (ESA) therapies, in addition to their mean weekly doses, during each quarter were recorded. Results The cohort included 1,096 patients with recorded SFOH prescriptions (mean age: 60.6 years; 65.8% male). There were small, but significant increases in ferritin from BL to Q1–Q4 (P Conclusion This real-world study showed that SFOH treatment in routine clinical practice for up to 1 year was associated with small increases in iron-related parameters and decreases in the use and mean dose of concomitant anti-anaemic therapies in European HD patients. The results from this study indicate that SFOH treatment may be associated with the reduction in concomitant IV iron and ESA use in HD patients, in line with previous findings from the Phase 3 study.

After reading with great interest the article entitled: “Exploring the impact of the COVID-19 pandemic on provision of cardiology services: a scoping review” redacted by Farah Yasmin et al., published by Reviews in Cardiovascular Medicine, we would like to add the following thoughts. Acute respiratory distress syndrome (ARDS) in Coronavirus disease 2019 (COVID-19) and pulmonary insufficiency reduces blood oxygen saturation and results in hypoxia. Therefore, the determining factor in the survival of patients with COVID-19 is their resistance to hypoxia. At the same time, it is the cardiovascular system that is an important and very sensitive link in the human adaptation to hypoxia. That is why it is necessary to carefully study the relationship between diseases of the heart, blood vessels, the reactivity of the cardiovascular system to hypoxia, and mortality in patients who develop ARDS with COVID-19.

Background: Haemodiafiltration (HDF) is the preferred dialysis modality in many countries. The aim of the study was to compare the survival of incident patients on high-volume HDF (HV-HDF) with high-flux haemodialysis (HD) in a large-scale European dialysis population. Methods: The study population was extracted from 47,979 patients in 369 NephroCare centres throughout 12 countries. Baseline was six months after dialysis initiation; maximum follow-up was 5 years. Patients were either on HV-HDF (defined as with ≥21 litres substitution fluid volume per session) or on HD if on that treatment for ≥75% of the 3 months before baseline. The main predictor was treatment modality. Other parameters included country, age, gender, BMI, haemoglobin, albumin and Charlson comorbidity index. Propensity score matching and Inverse Probability of Censoring Weighting (IPCW) were applied to reduce bias by indication and consider modality crossover, respectively. Results: After propensity score matching, 1,590 incident patients remained. Kaplan-Meier and proportional Cox regression analyses revealed no significant survival advantage of HV-HDF. Results were biased by modality crossover: during the 5-year study period, 7% of HV-HDF patients switched to HD, and 55% of HD patients switched to HV-HDF. IPCW uncovered a statistically significant survival advantage of HV-HDF (OR 0.501; CI 0.366-0.684; p < 0.001). A higher benefit of HV-HDF for some subgroups was revealed, for example, non-diabetics, patients 65-74 years, patients with obesity or high blood pressure. Conclusions: This large-scale study supports the generalizability of previous RCT findings regarding the survival benefit of HV-HDF. Sub-group analysis showed that some sub-cohorts appear to benefit more from HV-HDF than others.

Safety concerns with erythropoietin analogues and intravenous (IV) iron for treatment of anemia in CKD necessitate development of safer therapies. Roxadustat (FG-4592) is an orally bioavailable hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor that promotes coordinated erythropoiesis through HIF-mediated transcription. We performed an open-label, randomized hemoglobin (Hb) correction study in anemic (Hb≤10.0 g/dl) patients incident to hemodialysis (HD) or peritoneal dialysis (PD). Sixty patients received no iron, oral iron, or IV iron while treated with roxadustat for 12 weeks. Mean±SD baseline Hb was 8.3±1.0 g/dl in enrolled patients. Roxadustat at titrated doses increased mean Hb by ≥2.0 g/dl within 7 weeks regardless of baseline iron repletion status, C-reactive protein level, iron regimen, or dialysis modality. Mean±SEM maximal change in Hb from baseline (ΔHb(max)), the primary endpoint, was 3.1±0.2 g/dl over 12 weeks in efficacy-evaluable patients (n=55). In groups receiving oral or IV iron, ΔHb(max) was similar and larger than in the no-iron group. Hb response (increase in Hb of ≥1.0 g/dl from baseline) was achieved in 96% of efficacy-evaluable patients. Mean serum hepcidin decreased significantly 4 weeks into study: by 80% in HD patients receiving no iron (n=22), 52% in HD and PD patients receiving oral iron (n=21), and 41% in HD patients receiving IV iron (n=9). In summary, roxadustat was well tolerated and corrected anemia in incident HD and PD patients, regardless of baseline iron repletion status or C-reactive protein level and with oral or IV iron supplementation; it also reduced serum hepcidin levels.

WOS: 000372011100004, PubMed ID: 26627050, Objective: In patients with advanced kidney disease, metabolic and nutritional derangements induced by uremia interact and reinforce each other in a deleterious vicious circle. Literature addressing the effect of dialysis initiation on changes in body composition (BC) is limited and contradictory. The aim of this study was to evaluate changes in BC in a large international cohort of incident hemodialysis patients. Methods: A total of 8,227 incident adult end-stage renal disease patients with BC evaluation within the initial first 6 months of baseline, defined as 6 months after renal replacement therapy initiation, were considered. BC, including fat tissue index (FTI) and lean tissue index (LTI), were evaluated by Body Composition Monitor (BCM, Fresenius Medical Care, Bad Homburg, Germany). Exclusion criteria at baseline were lack of a BCM measurement before or after baseline, body mass index (BMI) 67 years, diabetes, male gender, high baseline LTI, and low baseline FTI were associated with a significant greater decrease of LTI. Conclusions: With the transition to hemodialysis, end-stage renal disease patients presented with distinctive changes in BC. These were mainly associated with gender, older age, presence of diabetes, low baseline FTI, and high baseline LTI. BMI increases did not fully represent the changes in BC. (C) 2016 The Authors. Published by Elsevier Inc.

Cinacalcet and vitamin D are often combined to treat secondary hyperparathyroidism (SHPT) in patients on dialysis. Independent effects on fibroblast growth factor-23 (FGF-23) concentrations in patients on hemodialysis administered cinacalcet or vitamin D analogs as monotherapies during treatment of SHPT are evaluated.A multicenter, randomized, open-label study to compare the efficacy of cinacalcet versus traditional vitamin D therapy for management of secondary hyperparathyroidism among subjects undergoing hemodialysis (PARADIGM) was a prospective, phase 4, multicenter, randomized, open-label study conducted globally. Participants (n=312) were randomized 1:1 to cinacalcet (n=155) or vitamin D analog (n=157) for 52 weeks. Levels of FGF-23 were measured at baseline and weeks 20 and 52. The absolute and percentage changes from baseline in plasma FGF-23, parathyroid hormone (PTH), calcium (Ca), phosphorus (P), and calcium-phosphorus product (Ca×P) were assessed. Correlations and logistic regression were used to explore relationships between changes in FGF-23 and changes in PTH, Ca, P, and Ca×P from baseline to week 52 by treatment arm.Median (quartiles 1, 3) decrease in FGF-23 concentrations was observed in the cinacalcet arm (-40%; -63%, 16%) compared with median increase in the vitamin D analog arm (47%; 0%, 132%) at week 52 (P0.001). Changes in FGF-23 in both arms were unrelated to changes in PTH (cinacalcet: r=0.17, P=0.11; vitamin D analog: r=-0.04, P=0.70). Changes in FGF-23 in the vitamin D analog but not the cinacalcet arm were correlated with changes in Ca (cinacalcet: r=0.11, P=0.30; vitamin D analog: r=0.32, P0.01) and P (cinacalcet: r=0.19, P=0.07; vitamin D analog: r=0.49, P0.001). Changes in FGF-23 were correlated with changes in Ca×P in both arms (cinacalcet: r=0.26, P=0.01; vitamin D analog: r=0.57, P0.001). Independent of treatment arm, participants with reductions in P or Ca×P were significantly more likely to show reductions in FGF-23.During treatment of SHPT, cinacalcet use was associated with a decrease in FGF-23 concentrations, whereas vitamin D analogs were associated with an increase. The divergent effects of these treatments on FGF-23 seem to be independent of modification of PTH. It is possible that effects of cinacalcet and vitamin D analogs on FGF-23 may be mediated indirectly by other effects on bone and mineral metabolism.

Direct comparison of cinacalcet and vitamin D analogs as monotherapies to lower parathyroid hormone (PTH) levels has not been undertaken.This was a prospective, multicenter, phase 4, randomized, open-label study that enrolled participants from 2010 to 2012. Adult participants (n=312) on hemodialysis with PTH450 pg/ml were randomized 1:1 to 12 months of treatment with either cinacalcet (n=155) or vitamin D analogs (n=157) to evaluate the mean percentage change in plasma PTH level (primary end point) and the proportion of participants achieving plasma PTH300 pg/ml or a ≥30% decrease in PTH (secondary end points). A preplanned analysis to determine whether there were important region-by-treatment interactions was also undertaken.Baseline mean PTH was 846 pg/ml (n=155) for cinacalcet and 816 pg/ml (n=157) for vitamin D analog therapy. The mean (95% confidence interval) percentage change from baseline in PTH was -12.1% (-20.0% to -4.1%) in the cinacalcet arm and -7.0% (-14.9% to 0.8%) in the vitamin D analog arm, a difference of -5.0% (-15.4% to 5.4%) (P=0.35). Similarly, there was no difference in achievement of secondary efficacy end points between arms (19.4% and 15.3% of participants with PTH≤300 pg/ml and 42.6% and 33.8% of participants had a PTH reduction30% in the cinacalcet and vitamin D analog arms, respectively). A prespecified analysis revealed a large treatment-by-region interaction, with nominally greater response to cinacalcet compared with vitamin D analogs in non-United States participants (US versus non-US participants, P0.001). Hypocalcemia was more common in the cinacalcet arm, whereas hypercalcemia and hyperphosphatemia occurred more often in the vitamin D analog arm.Participants had similar modest reductions in PTH with either cinacalcet or vitamin D analog monotherapy over 52 weeks of treatment, but effects varied by region. Treatments differed with regard to effect on calcium and phosphorus levels.

Two major issues need to be addressed when classifying the Soviet Union's history. One is the geopolitical coverage: which regions and nations are to be included, since many of those which are now part of the Soviet Union were once independent or belonged to other countries. Another is historical periodization. Four systems of periodization can be identified: two pre-1917 and two post-1917. The American classification schemes (DDC, LCC) are largely based on the official pre-1917 periodization of Russian history, while Soviet BBK is mostly Marxist. The three schemes are reviewed in terms of historiographic foundations, as well as their geopolitical coverage. Some problems in adjusting the classifications to changing situations are also discussed.