Objective: to investigate the antitumor effects of various forms of vitamin B12 in combination with various synergistic vitamins and evaluate the prospects for clinical applications.

Material and methods. Cell lines BT-474 (breast ductal carcinoma) and A549 (lung carcinoma) were used as an in vitro cell model, and transplantable epidermoid Lewis lung carcinoma (LLC) was used as an in vivo animal tumor model. Animal studies of LLC were carried out on 25 male F₁ hybrid mice (age 2.5–3 months, body weight 23–26 g). In silico research was conducted as a systematic computer analysis of 9,326 scientific sources.

Results. In vitro studies on cultures of two human tumor cell lines (BT-474 and A549) confirmed the cytotoxic effect of vitamin B12 (aquacobalamin). It has been shown that vitamin B12 has weak cytotoxic properties in the concentration range of 3.125–200 μg/L (IC50>200 nM), and its hydrophobic derivative (heptamethyl cyanoquacobyric acid ester) significantly reduces the survival of tumor lines. BT-474 and A549 cells at high concentrations (100–200 µg/l, IC50~100 nM). Experimental animals with an in vivo LLС model easily tolerated a drug based on vitamin B12. Exposure to the drug up to the 21^st day of LLС development was accompanied by an increasing tendency to inhibit tumor growth by 10–20% (р=0.059). The results of a systematic in silico review of the literature show that clinical data confirmed the significant antitumor effect of vitamin B12.

Conclusion. The cellular model indicated the antitumor properties of vitamin B12 and its hydrophobic derivative. With subchronic intragastric administration of B12 to tumor-bearing animals, a steady tendency to inhibit the LLС growth was observed. Analysis of clinical data confirmed the feasibility of the antitumor use of vitamin B12 individually and in combination with synergistic vitamins.

Objective: To analyze the legal and ethical aspects of regulating artificial intelligence (AI) in medicine in key jurisdictions (United States, European Union, China, Russia), to identify regulatory gaps, ethical dilemmas and prospects for harmonization of standards.

Material and methods. National and international regulatory documents (GDPR, AI Act, FDA, NMPA), scientific publications, clinical cases and regulatory initiatives (IMDRF, WHO) were reviewed. Methods for comparative legal analysis and systematization of ethical and legal norms were used.

Results. Considerable differences in approaches to AI regulation were identified, including flexibility in the US, the ethical centricity in the EU, centralization in China and an emerging framework in Russia. Key issues were emphasized, such as algorithmic bias, AI transparency, responsibility, and the conflict between innovation and security.

Conclusion. The harmonization of international standards, the introduction of dynamic regulation and the strengthening of interdisciplinary cooperation should be pursued to achieve a balance between innovation and the protection of patients' rights.

Nitric oxide NO is a signaling molecule involved in numerous physical and pathological processes in biological systems. Highly sensitive sensor materials for measuring NO amounts in vivo in exhaled air and in body fluids (saliva, blood, urine) can be a useful tool in diagnostics and management of patients with bronchopulmonary, cardiovascular, neurological and tumor diseases. Several approaches to measuring NO in biosubstrates (including exhaled air) have been developed: fluorescence/chemiluminescence, electron spin resonance, electrochemical/amperometric (organic and inorganic) and enzymatic/protein sensors. Semiconductors, transition metal nitrides, phthalocyanine complexes, porphyrin and cobalamin derivatives with metals can serve as materials for NO sensors. Creating sensor materials based on vitamin B12 derivatives is an urgent research task in biomedicine. The article systematizes information on using various compounds as materials for NO-sensitive and selective sensors to measure/evaluate NO levels in various biosubstrates.