Mammalian transglutaminases, a family of Ca2+-dependent proteins, are implicated in a variety of diseases. For example, celiac disease (CeD) is an autoimmune disorder whose pathogenesis requires transglutaminase 2 (TG2) to deamidate select glutamine residues in diet-derived gluten peptides. Deamidation involves the formation of transient γ-glutamyl thioester intermediates. Recent studies have revealed that in addition to the deamidated gluten peptides themselves, their corresponding thioester intermediates are also pathogenically relevant. A mechanistic understanding of this relevance is hindered by the absence of any structure of Ca2+-bound TG2. We report the X-ray crystallographic structure of human TG2 bound to an inhibitory gluten peptidomimetic and two Ca2+ ions in sites previously designated as S1 and S3. Together with additional structure-guided experiments, this structure provides a mechanistic explanation for how S1 regulates formation of an inhibitory disulfide bond in TG2, while also establishing that S3 is essential for γ-glutamyl thioester formation. Furthermore, our crystallographic findings and associated analyses have revealed that i) two interacting residues, H305 and E363, play a critical role in resolving the thioester intermediate into an isopeptide bond (transamidation) but not in thioester hydrolysis (deamidation); and ii) residues N333 and K176 stabilize preferred TG2 substrates and inhibitors via hydrogen bonding to nonreactive backbone atoms. Overall, the intermediate-state conformer of TG2 reported here represents a superior model to previously characterized conformers for both transition states of the TG2-catalyzed reaction.

RNA methylation is a widespread regulatory mechanism that controls gene expression in physiological processes. In recent years, the mechanisms and functions of RNA methylation under diseased conditions have been increasingly unveiled by RNA sequencing technologies with large scale and high resolution. In this review, the fundamental concept of RNA methylation is introduced, and the common types of transcript methylation and their machineries are described. Then, the regulatory roles of RNA methylation, particularly N6-methyladenosine and 5-methylcytosine, in the vascular lesions of ocular and cardiopulmonary diseases are discussed and compared. The ocular diseases include corneal neovascularization, retinopathy of prematurity, diabetic retinopathy, and pathologic myopia; whereas the cardiopulmonary ailments involve atherosclerosis and pulmonary hypertension. This review hopes to shed light on the common regulatory mechanisms underlying the vascular lesions in these ocular and cardiopulmonary diseases, which may be conducive to developing therapeutic strategies in clinical practice.

Artificial intelligence (AI)-based clinical decision support systems are gaining momentum by relying on a greater volume and variety of secondary use data. However, the uncertainty, variability, and biases in real-world data environments still pose significant challenges to the development of health AI, its routine clinical use, and its regulatory frameworks. Health AI should be resilient against real-world environments throughout its lifecycle, including the training and prediction phases and maintenance during production, and health AI regulations should evolve accordingly. Data quality issues, variability over time or across sites, information uncertainty, human-computer interaction, and fundamental rights assurance are among the most relevant challenges. If health AI is not designed resiliently with regard to these real-world data effects, potentially biased data-driven medical decisions can risk the safety and fundamental rights of millions of people. In this viewpoint, we review the challenges, requirements, and methods for resilient AI in health and provide a research framework to improve the trustworthiness of next-generation AI-based clinical decision support.

The classical pathway of the complement system is activated by the binding of C1q in the C1 complex to the target activator, including immune complexes. Factor H is regarded as the key downregulatory protein of the complement alternative pathway. However, both C1q and factor H bind to target surfaces via charge distribution patterns. For a few targets, C1q and factor H compete for binding to common or overlapping sites. Factor H, therefore, can effectively regulate the classical pathway activation through such targets, in addition to its previously characterized role in the alternative pathway. Both C1q and factor H are known to recognize foreign or altered-self materials, e.g., bacteria, viruses, and apoptotic/necrotic cells. Clots, formed by the coagulation system, are an example of altered self. Factor H is present abundantly in platelets and is a well-known substrate for FXIIIa. Here, we investigated whether clots activate the complement classical pathway and whether this is regulated by factor H. We show here that both C1q and factor H bind to the fibrin formed in microtiter plates and the fibrin clots formed under in vitro physiological conditions. Both C1q and factor H become covalently bound to fibrin clots, and this is mediated via FXIIIa. We also show that fibrin clots activate the classical pathway of complement, as demonstrated by C4 consumption and membrane attack complex detection assays. Thus, factor H downregulates the activation of the classical pathway induced by fibrin clots. These results elucidate the intricate molecular mechanisms through which the complement and coagulation pathways intersect and have regulatory consequences.

Sigma factors are transcriptional regulators that are part of complex regulatory networks for major cellular processes, as well as for growth phase-dependent regulation and stress response. Actinoplanes sp. SE50/110 is the natural producer of acarbose, an α-glucosidase inhibitor that is used in diabetes type 2 treatment. Acarbose biosynthesis is dependent on growth, making sigma factor engineering a promising tool for metabolic engineering. ACSP50_0507 is a homolog of the developmental and osmotic-stress-regulating Streptomyces coelicolor σHSc. Therefore, the protein encoded by ACSP50_0507 was named σHAs. Here, an Actinoplanes sp. SE50/110 expression strain for the alternative sigma factor gene ACSP50_0507 (sigHAs) achieved a two-fold increased acarbose yield with acarbose production extending into the stationary growth phase. Transcriptome sequencing revealed upregulation of acarbose biosynthesis genes during growth and at the late stationary growth phase. Genes that are transcriptionally activated by σHAs frequently code for secreted or membrane-associated proteins. This is also mirrored by the severely affected cell morphology, with hyperbranching, deformed and compartmentalized hyphae. The dehydrated cell morphology and upregulation of further genes point to a putative involvement in osmotic stress response, similar to its S. coelicolor homolog. The DNA-binding motif of σHAs was determined based on transcriptome sequencing data and shows high motif similarity to that of its homolog. The motif was confirmed by in vitro binding of recombinantly expressed σHAs to the upstream sequence of a strongly upregulated gene. Autoregulation of σHAs was observed, and binding to its own gene promoter region was also confirmed.

The flavonoids in citrus fruits are crucial physiological regulators and natural bioactive products of high pharmaceutical value. Melatonin is a pleiotropic hormone that can regulate plant morphogenesis and stress resistance and alter the accumulation of flavonoids in these processes. However, the direct effect of melatonin on citrus flavonoids remains unclear. In this study, nontargeted metabolomics and transcriptomics were utilized to reveal how exogenous melatonin affects flavonoid biosynthesis in \"Bingtangcheng\" citrus fruits. The melatonin treatment at 0.1 mmol L-1 significantly increased the contents of seven polymethoxylated flavones (PMFs) and up-regulated a series of flavonoid pathway genes, including 4CL (4-coumaroyl CoA ligase), FNS (flavone synthase), and FHs (flavonoid hydroxylases). Meanwhile, CHS (chalcone synthase) was down-regulated, causing a decrease in the content of most flavonoid glycosides. Pearson correlation analysis obtained 21 transcription factors co-expressed with differentially accumulated flavonoids, among which the AP2/EREBP members were the most numerous. Additionally, circadian rhythm and photosynthesis pathways were enriched in the DEG (differentially expressed gene) analysis, suggesting that melatonin might also mediate changes in the flavonoid biosynthesis pathway by affecting the fruit\'s circadian rhythm. These results provide valuable information for further exploration of the molecular mechanisms through which melatonin regulates citrus fruit metabolism.

Global support and standardization of regulation for biosimilars approval owes much of its legacy to the World Health Organization (WHO), since the first guidance by the organization on the matter was released in 2009. Since then, and with over a decade of research, the 2022 revision provides opportunities for time and financial savings to pharmaceutical manufacturers aiming to prove similarity of a potential biosimilar product to some reference product, particularly by clarifying that the use of a non-local reference product as a comparator in certain studies is permissible. This declaration has important implications, particularly in the emerging biological markets of the Middle East and North Africa region, where WHO guidelines have been integral to the regulatory framework of over a dozen countries for more than a decade. This article aims to review the impact of this revision on these countries and relevant policies on non-local comparator usage. Since 2022, this revision has been adopted only in Egypt. Many North African countries are yet to adopt a first draft of the formalized guidance. This analysis revealed that, although many of these countries reference the WHO guidelines, hesitation remains in terms of sourcing comparator products outside the US or European countries. This likely translates to slow regional development and cooperation of functioning, sustainable biosimilars markets. Future studies will be necessary to evaluate the continued development of guidance within these countries and changes in comparator sourcing norms as more time is allowed for their policies to mature and adapt to new standards.

This paper interrogates the depoliticising effects of a seemingly neutral regulatory drive at the heart of the World Health Organization (WHO)\'s promotion of traditional medicine. Emerging at WHO in the late 1960s against a political backdrop of decolonisation and pan-Africanism, traditional medicine has continued to be promoted in subsequent decades, culminating in the latest global Traditional Medicine Strategy (2014 to 2023). Yet WHO\'s promotion and acceptance of traditional medicine have also become increasingly conditional upon its standardisation and regulation - something that appears fundamentally at odds with traditional medicine\'s heterogeneity. Drawing on insights from critical law and science and technology studies, we suggest that such a process at WHO has done more than simply disqualify the toxic and the dangerous. Rather, it has implicitly and explicitly marginalised and excluded those aspects of traditional medicine that deviate from scientific, biomedical ways of seeing, knowing and organising.

Vibrio parahaemolyticus possesses two distinct type VI secretion systems (T6SS), namely T6SS1 and T6SS2. T6SS1 is predominantly responsible for adhesion to Caco-2 and HeLa cells and for the antibacterial activity of V. parahaemolyticus, while T6SS2 mainly contributes to HeLa cell adhesion. However, it remains unclear whether the T6SS systems have other physiological roles in V. parahaemolyticus. In this study, we demonstrated that the deletion of icmF2, a structural gene of T6SS2, reduced the biofilm formation capacity of V. parahaemolyticus under low salt conditions, which was also influenced by the incubation time. Nonetheless, the deletion of icmF2 did not affect the biofilm formation capacity in marine-like growth conditions, nor did it impact the flagella-driven swimming and swarming motility of V. parahaemolyticus. IcmF2 was found to promote the production of the main components of the biofilm matrix, including extracellular DNA (eDNA) and extracellular proteins, and cyclic di-GMP (c-di-GMP) in V. parahaemolyticus. Additionally, IcmF2 positively influenced the transcription of cpsA, mfpA, and several genes involved in c-di-GMP metabolism, including scrJ, scrL, vopY, tpdA, gefA, and scrG. Conversely, the transcription of scrA was negatively impacted by IcmF2. Therefore, IcmF2-dependent biofilm formation was mediated through its effects on the production of eDNA, extracellular proteins, and c-di-GMP, as well as its impact on the transcription of cpsA, mfpA, and genes associated with c-di-GMP metabolism. This study confirmed new physiological roles for IcmF2 in promoting biofilm formation and c-di-GMP production in V. parahaemolyticus.

BACKGROUND: Software as a medical device (SaMD) has gained the attention of medical device regulatory bodies as the prospects of standalone software for use in diagnositic and therapeutic settings have increased. However, to date, figures related to SaMD have not been made available by regulators, which limits the understanding of how prevalent these devices are and what actions should be taken to regulate them.
OBJECTIVE: The aim of this study is to empirically evaluate the market approvals and clearances related to SaMD and identify adverse incidents related to these devices.
METHODS: Using databases managed by the US medical device regulator, the US Food and Drug Administration (FDA), we identified the counts of SaMD registered with the FDA since 2016 through the use of product codes, mapped the path SaMD takes toward classification, and recorded adverse events.
RESULTS: SaMD does not seem to be registered at a rate dissimilar to that of other medical devices; thus, adverse events for SaMD only comprise a small portion of the total reported number.
CONCLUSIONS: Although SaMD has been identified in the literature as an area of development, our analysis suggests that this growth has been modest. These devices are overwhelmingly classified as moderate to high risk, and they take a very particular path to that classification. The digital revolution in health care is less pronounced when evidence related to SaMD is considered. In general, the addition of SaMD to the medical device market seems to mimic that of other medical devices.