Numerous studies have shown that changes in the intestinal microbial-tissue complex are a risk factor for the progression of chronic kidney disease (CKD) to end-stage renal disease and, therefore, a potential target for new therapeutic interventions. Thus, reliable and sensitive diagnostic tools for measuring intestinal permeability in the clinical setting are necessary. Modern genome sequencing and multi-omics technologies have established that patients with CKD are characterized by a specific imbalance between the saccharolytic and proteolytic microbiota, contributing to the accumulation of numerous toxic microbial products, such as indoxyl sulphate, p-cresyl sulphate, trimethylamine-N-oxide. Progressive kidney function decline leads to compensatory urea accumulation in the gastrointestinal tract. In the intestinal lumen, urea is hydrolyzed by microbial urease, forming a large amount of ammonium hydroxide, which may be accompanied by disruption of the epithelial barrier integrity with an increase in intestinal permeability for microbial molecules that initiate systemic inflammation. Experimental approaches to studying the intestinal barrier in CKD include the assessment of electrophysiological parameters of the intestinal epithelium and the transport of fluorescently labelled tracers in the Ussing chamber. Actively improving various cell-based in vitro methods, which may be useful for studying the effect of microbiota on the barrier functions of the intestinal epithelium. Gene expression and protein content of tight junctions are estimated using polymerase chain reaction, immunohistochemical methods and Western blotting. Using various biomolecular methods, it was found that renal failure is characterized by the presence of inflammatory and atrophic changes throughout the gastrointestinal tract, destruction of the mucin layer, damage to tight junctions with a decrease in the amount of claudine-1, occludin and ZO-1 as well as a decrease in transepithelial electrical resistance. Clinical examination of intestinal permeability by methods based on the urine excretion of orally administered sugars, polyethylene glycol polymers and labelled tracers indicate a distortion of the results in patients with CKD due to altered renal clearance. Alternatively, quantitative determination of bacterial DNA and D-lactate levels in the blood is considered. Identification of serum non-coding microRNAs, confocal laser endomicroscopy and impedance spectroscopy have the potential to be used as methods for assessing intestinal barrier function.

The course of the COVID-19 pandemic has led to a critical increase in the burden on virtually all major branches of the health care system in our country and abroad.   The aim of this article is to analyse the activities of the different parts of the city nephrol­ogy service in Saint-Petersburg and to consider promising ways to improve it.   The nephrology service for the adult population in St. Petersburg includes: outpatient service; inpatient service - 183 beds in 24-hour inpatient departments of the city; dialysis service - 10 dialysis units in municipal medical organizations, 5 in federal institutions, and 8 centers/departments operating in the framework of private-public partnership. The number of patients on dialysis programme decreased by 10.5 % to 1,839 in 2021. These changes are likely due to an increase in mortality among these patients in 2020 and 2021 which is a consequence not only of COVID-19 but also of the adverse impact of the pandemic on the health system. The proportion of patients treated as outpatients in private dialysis centres increased during the three-year period. The incidence of arteriovenous fistula formation in primary vascular access decreased from 33.2 % to 14.2 % in 2020 compared with 2019. At the same time, the use of temporary central venous catheters as primary vascular access for renal replacement therapy has increased significantly from 43.0 % to 61.9 %. The development of the nephrology service is largely determined by its funding. To compensate the costs of medical in­ stitutions in the city for conducting renal replacement therapy it is necessary to increase the tariffs of compulsory health insurance (CHI) by at least 50 %. In the medical organizations of Saint-Petersburg municipal and federal subordination the share of "artificial kidney" devices that have used up their resource is 32.2 %, and in a number of medical institutions it exceeds 50 %.

IgG4-related disease (IgG4-RD) currently is considered as a chronic fibroinflammatory immune-mediated multisystemic condition of unidentified etiology, which can imitate a wide range of malignant, infectious, rheumatologic, and other diseases. It can affect almost any organ system in the body synchronously or sequentially, but the most often affected are the pancreas, hepatobiliary tract, periorbital structures, salivary glands, kidneys, and lymph nodes. The most frequent renal manifestations of IgG4-RD is IgG4-related tubulointerstitial nephritis. Membranous nephropathy is the most common glomerular disease accompanied by IgG4-RD. Regardless of the organ localization, patients with IgG4-RD are characterized by elevated serum IgG4, but this laboratory abnormality is not specific and can be changed in other diseases. In all suspected cases of IgG4-RD the diagnosis should be confirmed by histological examination. Characteristic pathologic features include diffuse or focal lymphoplasmacytic infiltration with prominent IgG4+ plasma cells, storiform fibrosis, and obliterative phlebitis. Patients with IgG4- RD usually have an excellent clinical response to glucocorticoids, but relapse rates after steroid withdrawal are high, which may require additional use of immunosuppressants or rituximab. Due to the low prevalence and multitude of clinical manifestations the disease often remains underdiagnosed on time. This case report describes middle-aged patients with a history of chronic recurrent pancreatitis complicated by the nephrotic syndrome. Kidney biopsy showed membranous nephropathy and diagnosis IgG4-RD with multiorgan involvement was made. Partial remission was achieved on corticosteroid therapy. The presented case clearly demonstrates the difficulties of diagnosis and treatment of IgG4-RD. IgG4-related membranous nephropathy should be included in the differential diagnosis for patients with nephrotic syndrome accompanied by multiorgan dysfunction.

Anti‑NMDA encephalitis is a rare autoimmune disease of the central nervous system caused by the synthesis of autoantibodies to the NR1/NR2 subunits of the NMDA receptor, characterized by the development of acute mental, cognitive, motor, autonomic disorders, epileptic syndrome and central hypoventilation.The article presents a three‑year observation of patient 34 years old with anti‑NMDA ncephalitis associated with late‑ stage ovarian teratoma, accompanied by an increase titer of antibodies to NMDA receptors in serum to 1:640.Based on a detailed analysis of clinical, neurological, neuropsychological (MMSE, MoСA, FAB, 10 words test A.R. Luria) and laboratory‑instrumental characteristics of the disease (titer anti‑NMDA, level of IgG, IgM, IgA, lymphocyte subpopulations, EEG, MRI of the brain, pelvis) suggested a combination scheme of first and second line therapy. The sequential use of two cycles of medium‑volume membrane plasmapheresis (25–30 % of the circulating plasma volume, No. 5 + 5) was carried out in combination with pulse therapy with methylprednisolone 1.0 (No. 4 + 3) and cyclophasphamide 1.0 (No. 2 + 1) on background of persistent ovarian teratoma. Symptom regression was achieved by the end of the first cycle, and full recovery to the initial level of cognitive functions occurred after the second cycle, while maintaining the anti‑NMDA antibody titer to 1:160. After removal of ovarian teratoma, the level of anti‑NMDA decreased in a month to 1:40, and after 7 months it reached normal values (<1:10) against the background of basic pill therapy with methotrexate 12.5 mg/week.Thus, a rational combination and sequence of first and second line therapy and therapeutic apheresis, taking into account the pathogenetic features of each phase of the disease, can quickly achieve complete stable remission in patient with anti‑NMDA encephalitis.