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Background/Objectives: Dietary fibers play key roles in shaping gut microbiome and intestinal homeostasis. While purified diets offer experimental precision and reproducibility in rodent models, they omit the complex mixture of fermentable and non-fermentable fibers found in grain-based chow diets. We hypothesized that excluding fermentable fiber impairs intestinal homeostasis by reducing microbial metabolites and altering the colonic epithelial transcriptome, thereby increasing susceptibility to inflammation. Methods: Wildtype male C57BL/6 mice were maintained on either a standard grain-based chow diet or a purified low-fat diet (LFD) containing 5% non-fermentable cellulose for ten weeks. Fecal microbiomes, short-chain fatty acid (SCFA) profiles, and colonic epithelial transcriptomes were analyzed. A separate group was challenged with dextran sodium sulfate (DSS) following a five-week dietary intervention to compare colitis severity between the two diet groups. Results: Relative to mice fed the grain-based chow, those consuming the purified LFD (containing only non-fermentable cellulose) showed decreased gut microbial diversity and significantly lower SCFA levels. These changes were accompanied by marked differences in colonic epithelial cell transcriptomes. In LFD-fed mice, the top upregulated gene networks included ribosomal pathways and MHC complex protein binding, suggesting increased growth and gut inflammation. The most downregulated pathways included mineral absorption, actin and tubulin binding, and membrane organelle assembly, indicating major alterations in cellular structure and transport. LFD-fed mice also exhibited increased colonic expression of S100a9, a gut inflammation biomarker, and more severe disease symptoms when challenged with DSS compared to chow-fed mice. Conclusions: Fermentable fibers are one of the factors contributing to intestinal homeostasis and mitigating the severity of ulcerative colitis.

Recent advances in metabolic engineering have demonstrated the potential to exploit biological chemistry for the synthesis of complex molecules. Much of the progress to date has leveraged increasingly precise genetic tools to control the transcription and translation of enzymes for superior biosynthetic pathway performance. However, applying these approaches and principles to the synthesis of more complex natural products will require a new set of tools for enabling various classes of metabolic chemistries (i.e., cyclization, oxygenation, glycosylation, and halogenation) in vivo. Of these diverse chemistries, oxygenation is one of the most challenging and pivotal for the synthesis of complex natural products. Here, using Taxol as a model system, we use nature’s favored oxygenase, the cytochrome P450, to perform high-level oxygenation chemistry in Escherichia coli. An unexpected coupling of P450 expression and the expression of upstream pathway enzymes was discovered and identified as a key obstacle for functional oxidative chemistry. By optimizing P450 expression, reductase partner interactions, and N-terminal modifications, we achieved the highest reported titer of oxygenated taxanes (∼570 ± 45 mg/L) in E. coli. Altogether, this study establishes E. coli as a tractable host for P450 chemistry, highlights the potential magnitude of protein interdependency in the context of synthetic biology and metabolic engineering, and points to a promising future for the microbial synthesis of complex chemical entities.

Despite considerable progress in understanding the pathogenesis of Mycobacterium tuberculosis (Mtb), development of new therapeutics and vaccines against it has proven difficult. This is at least in part due to the use of less than optimal models of in-vivo Mtb infection, which has precluded a study of the physiology of the pathogen in niches where it actually persists. C3HeB/FeJ (Kramnik) mice develop human-like lesions when experimentally infected with Mtb and thus make available, a faithful and highly tractable system to study the physiology of the pathogen in-vivo. We compared the transcriptomics of Mtb and various mutants in the DosR (DevR) regulon derived from Kramnik mouse granulomas to those cultured in-vitro. We recently showed that mutant ΔdosS is attenuated in C3HeB/FeJ mice. Aerosol exposure of mice with the mutant mycobacteria resulted in a substantially different and a relatively weaker transcriptional response (< = 20 genes were induced) for the functional category 'Information Pathways' in Mtb:ΔdosR; 'Lipid Metabolism' in Mtb:ΔdosT; 'Virulence, Detoxification, Adaptation' in both Mtb:ΔdosR and Mtb:ΔdosT; and 'PE/PPE' family in all mutant strains compare to wild-type Mtb H37Rv, suggesting that the inability to induce DosR functions to different levels can modulate the interaction of the pathogen with the host. The Mtb genes expressed during growth in C3HeB/FeJ mice appear to reflect adaptation to differential nutrient utilization for survival in mouse lungs. The genes such as glnB, Rv0744c, Rv3281, sdhD/B, mce4A, dctA etc. downregulated in mutant ΔdosS indicate their requirement for bacterial growth and flow of carbon/energy source from host cells. We conclude that genes expressed in Mtb during in-vivo chronic phase of infection in Kramnik mice mainly contribute to growth, cell wall processes, lipid metabolism, and virulence.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is the leading cause of death from an infectious disease worldwide. Over the course of its life cycle in vivo, Mtb is exposed to a plethora of environmental stress conditions. Temporal regulation of genes involved in sensing and responding to such conditions is therefore crucial for Mtb to establish an infection. The Rv2745c (clgR) gene encodes a Clp protease gene regulator that is induced in response to a variety of stress conditions and potentially plays a role in Mtb pathogenesis. Our isogenic mutant, Mtb:ΔRv2745c, is significantly more sensitive to in vitro redox stress generated by diamide, relative to wild-type Mtb as well as to a complemented strain. Together with the fact that the expression of Rv2745c is strongly induced in response to redox stress, these results strongly implicate a role for ClgR in the management of intraphagosomal redox stress. Additionally, we observed that redox stress led to the dysregulation of the expression of the σH/σE regulon in the isogenic mutant, Mtb:ΔRv2745c. Furthermore, induction of clgR in Mtb and Mtb:ΔRv2745c (comp) did not lead to Clp protease induction, indicating that clgR has additional functions that need to be elucidated. Our data, when taken together with that obtained by other groups, indicates that ClgR plays diverse roles in multiple regulatory networks in response to different stress conditions. In addition to redox stress, the expression of Rv2745c correlates with the expression of genes involved in sulfate assimilation as well as in response to hypoxia and reaeration. Clearly, the Mtb Rv2745c-encoded ClgR performs different functions during stress response and is important for the pathogenicity of Mtb in-vivo, regardless of its induction of the Clp proteolytic pathway.

BackgroundWorldwide, healthcare workers who face a higher risk of contracting coronavirus disease 2019 (COVID-19) were among the first to receive COVID-19 vaccinations. Following the initial two vaccine doses, health experts recommended a third booster shot to enhance protection against the severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) virus. However, limited information about how this booster dose affects antibody levels is available. This study assesses the immune response triggered by the ChAdOx1 (Covishield) booster dose.MethodsWe conducted a before and after study among 132 healthcare providers at a tertiary care hospital in India who had already received their initial COVID-19 vaccine doses and agreed to participate. A booster shot was administered nine months following their second vaccine dose per the prevalent norms. We collected blood samples to measure immunoglobulin-G (IgG) levels against the spike protein's receptor-binding domain of the SARS-CoV-2 virus. These blood samples were taken both when they received the booster shot and one month after the booster. We determined IgG levels using a chemiluminescence microparticle immunoassay.ResultAmong the participants, approximately 54% were females. Regarding occupation, about 36% were doctors, 30% were students, 20% were nursing officers, and the remaining 14% held grade-4 positions. The median age of the participants was 32 years. About 74% had no history of underlying health conditions. Before the booster dose, 29% of the participants tested negative for antibodies. However, all participants developed antibodies following the booster shot, and there was a significant increase in antibody levels, which was statistically meaningful with a p-value of less than 0.0001.ConclusionIn conclusion, the administration of a booster dose effectively induced seroconversion and significantly increased antibody levels among healthcare providers, enhancing their immunity against COVID-19, essential in the face of a waning immune response to primary series vaccination.

Breast conserving therapy is now considered the preferred option for early invasive and in situ ductal (DCIS) breast carcinoma. In an attempt to decrease positive margin and local recurrence, various methods for margin delineation have been described. Our team at AIIMS New Delhi have developed a new technique of injecting methylene blue at the sonographically determined margin of tumour to delineate the margin of excision for breast cancer. We perform this procedure after immobilization of tumour with a transparent Ioban/Opsite adhesive sheet applied over the breast. The injection of blue dye at sonographically determined margins facilitates the lumpectomy with free margins.

Despite considerable progress in understanding the pathogenesis of Mycobacterium tuberculosis (Mtb), development of new therapeutics and vaccines against it has proven difficult. This is at least in part due to the use of less than optimal models of in-vivo Mtb infection, which has precluded a study of the physiology of the pathogen in niches where it actually persists. C3HeB/FeJ (Kramnik) mice develop human-like lesions when experimentally infected with Mtb and thus make available, a faithful and highly tractable system to study the physiology of the pathogen in-vivo. We compared the tran = 20 genes were induced) for the functional category 'Information Pathways' in Mtb: Delta dosR; 'Lipid Metabolism' in Mtb: Delta dosT; 'Virulence, Detoxification, Adaptation' in both Mtb: Delta dosR and Mtb: Delta dosT; and 'PE/PPE' family in all mutant strains compare to wild-type Mtb H37Rv, suggesting that the inability to induce DosR functions to different levels can modulate the interaction of the pathogen with the host. The Mtb genes expressed during growth in C3HeB/FeJ mice appear to reflect adaptation to differential nutrient utilization for survival in mouse lungs. The genes such as glnB, Rv0744c, Rv3281, sdhD/B, mce4A, dctA etc. downregulated in mutant Delta dosS indicate their requirement for bacterial growth and flow of carbon/energy source from host cells. We conclude that genes expressed in Mtb during in-vivo chronic phase of infection in Kramnik mice mainly contribute to growth, cell wall processes, lipid metabolism, and virulence.

Introduction: Spinal cord ependymoma seldom presents with holocord syringomyelia in pediatric age-group. Association of ependymoma with a lipoma is also rare. The child presented critically ill with polymicrobial pneumonia, and the neurologic findings were missed until recovery. We report a case highlighting these findings. Case Report: A 16-year-old adolescent presented critically ill with respiratory failure due to severe pneumonia. Evaluation showed fungal pneumonia with secondary bacterial infection. On recovery, she had nasal regurgitation and required nasogastric tube feeding. Examination showed palatal and left vocal cord palsy. Neuroimaging of brain showed conus cauda tumor with syringobulbia and holocord multiseptate syrinx extending from medulla to filum terminale with lipoma. Histopathology examination showed myxopapillary ependymoma. She improved with excision and postoperative radiotherapy. Discussion: Our case is a rare report of an adolescent girl with conus cauda tumor and holocord syrinx.