Recent Trends in the Pretreatment of Lignocellulosic Biomass for Value-Added Products

Lignocellulosic biomass (LCB) is the most abundantly available bioresource amounting to about a global yield of up to 1. 3 billion tons per year. The hydrolysis of LCB results in the release of various reducing sugars which are highly valued in the production of biofuels such as bioethanol and biogas, various organic acids, phenols, and aldehydes. The majority of LCB is composed of biological polymers such as cellulose, hemicellulose, and lignin, which are strongly associated with each other by covalent and hydrogen bonds thus forming a highly recalcitrant structure. The presence of lignin renders the bio-polymeric structure highly resistant to solubilization thereby inhibiting the hydrolysis of cellulose and hemicellulose which presents a significant challenge for the isolation of the respective bio-polymeric components. This has led to extensive research in the development of various pretreatment techniques utilizing various physical, chemical, physicochemical, and biological approaches which are specifically tailored toward the source biomaterial and its application. The objective of this review is to discuss the various pretreatment strategies currently in use and provide an overview of their utilization for the isolation of high-value bio-polymeric components. The article further discusses the advantages and disadvantages of the various pretreatment methodologies as well as addresses the role of various key factors that are likely to have a significant impact on the pretreatment and digestibility of LCB

Identification of Inhibitors against Mycobacterium tuberculosis Thiamin Phosphate Synthase, an Important Target for the Development of Anti-TB Drugs

Tuberculosis (TB) continues to pose a serious challenge to human health afflicting a large number of people throughout the world. In spite of the availability of drugs for the treatment of TB, the non-compliance to 6–9 months long chemotherapeutic regimens often results in the emergence of multidrug resistant strains of Mycobacterium tuberculosis adding to the precariousness of the situation. This has necessitated the development of more effective drugs. Thiamin biosynthesis, an important metabolic pathway of M.tuberculosis, is shown to be essential for the intracellular growth of this pathogen and hence, it is believed that inhibition of this pathway would severely affect the growth of M.tuberculosis. In this study, a comparative homology model of M.tuberculosis thiamin phosphate synthase (MtTPS) was generated and employed for virtual screening of NCI diversity set II to select potential inhibitors. The best 39 compounds based on the docking results were evaluated for their potential to inhibit the MtTPS activity. Seven compounds inhibited MtTPS activity with IC50 values ranging from 20 – 100 µg/ml and two of these exhibited weak inhibition of M.tuberculosis growth with MIC99 values being 125 µg/ml and 162.5 µg/ml while one compound was identified as a very potent inhibitor of M.tuberculosis growth with an MIC99 value of 6 µg/ml. This study establishes MtTPS as a novel drug target against M.tuberculosis leading to the identification of new lead molecules for the development of antitubercular drugs. Further optimization of these lead compounds could result in more potent therapeutic molecules against Tuberculosis

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Antigen identification strategies and preclinical evaluation models for advancing tuberculosis vaccine development

Abstract In its myriad devastating forms, Tuberculosis (TB) has existed for centuries, and humanity is still affected by it. Mycobacterium tuberculosis (M. tuberculosis), the causative agent of TB, was the foremost killer among infectious agents until the COVID-19 pandemic. One of the key healthcare strategies available to reduce the risk of TB is immunization with bacilli Calmette-Guerin (BCG). Although BCG has been widely used to protect against TB, reports show that BCG confers highly variable efficacy (0-80%) against adult pulmonary TB. Unwavering efforts have been made over the past 20 years to develop and evaluate new TB vaccine candidates. The failure of conventional preclinical animal models to fully recapitulate human response to TB, as also seen for the failure of MVA85A in clinical trials, signifies the need to develop better preclinical models for TB vaccine evaluation. In the present review article, we outline various approaches used to identify protective mycobacterial antigens and recent advancements in preclinical models for assessing the efficacy of candidate TB vaccines

An attenuated quadruple gene mutant of Mycobacterium tuberculosis imparts protection against tuberculosis in guinea pigs

Previously we had developed a triple gene mutant of Mycobacterium tuberculosis (MtbΔmms) harboring disruption in three genes, namely mptpA, mptpB and sapM. Though vaccination with MtbΔmms strain induced protection in the lungs of guinea pigs, the mutant strain failed to control the hematogenous spread of the challenge strain to the spleen. Additionally, inoculation with MtbΔmms resulted in some pathological damage to the spleens in the early phase of infection. In order to generate a strain that overcomes the pathology caused by MtbΔmms in spleen of guinea pigs and controls dissemination of the challenge strain, MtbΔmms was genetically modified by disrupting bioA gene to generate MtbΔmmsb strain. Further, in vivo attenuation of MtbΔmmsb was evaluated and its protective efficacy was assessed against virulent M. tuberculosis challenge in guinea pigs. MtbΔmmsb mutant strain was highly attenuated for growth and virulence in guinea pigs. Vaccination with MtbΔmmsb mutant generated significant protection in comparison to sham-immunized animals at 4 and 12 weeks post-infection in lungs and spleen of infected animals. However, the protection imparted by MtbΔmmsb was significantly less in comparison to BCG immunized animals. This study indicates the importance of attenuated multiple gene deletion mutants of M. tuberculosis for generating protection against tuberculosis

Disruption of Mycobactin Biosynthesis Leads to Attenuation of Mycobacterium tuberculosis for Growth and Virulence

10.1093/infdis/jit250The Journal of Infectious Diseases20881255-126

Evaluation of the gross pathological damage of the organs of vaccinated guinea pigs at 4 weeks post challenge.

<p>(a) The figure depicts representative photographs of lungs, spleen and liver of guinea pigs belonging to different groups of vaccination at 4 weeks post challenge. Graphical representation of gross pathological scores assigned to the lungs, spleen and liver of guinea pigs euthanized at 4 weeks post challenge is represented alongside. Each data point represents the score assigned to an individual animal. The bar depicts median (± interquartile range) for each group. * <i>p</i> <0.05 and **<i>p</i> <0.01 (Kruskal-Wallis test followed by the Dunn's multiple comparison test). (b) The graphical representation of organ (lungs and spleen) weights of guinea pigs at 4 weeks post challenge. The bar depicts mean (± SD) for each group. * <i>p</i> <0.05, **<i>p</i> <0.01 and ***<i>p</i> <0.001 [unpaired (two-tailed) <i>t</i>-test].</p

Evaluation of protective efficacy of MtbΔ<i>bioA</i> in guinea pig model of experimental tuberculosis.

<p>(a) Experimental protocol for assessing the protective efficacy of MtbΔ<i>bioA</i> against infection with virulent <i>M</i>. <i>tuberculosis</i> in guinea pigs. Guinea pigs (n = 6) were vaccinated with BCG or a single dose of MtbΔ<i>bioA</i> or two doses of MtbΔ<i>bioA</i> administered at 6-week interval (Δ<i>bioA/</i> Δ<i>bioA</i>). Vaccinated guinea pigs were challenged via the aerosol route with ~50 bacilli of virulent <i>M</i>. <i>tuberculosis</i> at 12 weeks from primary immunization and euthanized at 4 weeks post challenge. Sham-immunized animals were taken as control. (b, c) Enumeration of bacillary load in the lungs and spleen of vaccinated guinea pigs at 4 weeks post challenge. In both lungs and spleen, MtbΔ<i>bioA</i> imparted significant protection over sham-immunized controls. Booster dose with MtbΔ<i>bioA</i> failed to confer any improvement in protective efficacy imparted by single dose of MtbΔ<i>bioA</i>. Each data point represents the log₁₀ CFU/ organ for an individual animal and the bar depicts mean (±SE) for each group. **<i>p</i> <0.01 and ***<i>p</i> <0.001 (one-way ANOVA followed by Tukey’s multiple comparison test).</p

<i>bioA</i> mutant of <i>Mycobacterium tuberculosis</i> shows severe growth defect and imparts protection against tuberculosis in guinea pigs

<div><p>Owing to the devastation caused by tuberculosis along with the unsatisfactory performance of the Bacillus Calmette–Guérin (BCG) vaccine, a more efficient vaccine than BCG is required for the global control of tuberculosis. A number of studies have demonstrated an essential role of biotin biosynthesis in the growth and survival of several microorganisms, including mycobacteria, through deletion of the genes involved in <i>de novo</i> biotin biosynthesis. In this study, we demonstrate that a <i>bioA</i> mutant of <i>Mycobacterium tuberculosis</i> (MtbΔ<i>bioA</i>) is highly attenuated in the guinea pig model of tuberculosis when administered aerogenically as well as intradermally. Immunization with MtbΔ<i>bioA</i> conferred significant protection in guinea pigs against an aerosol challenge with virulent <i>M</i>. <i>tuberculosis</i>, when compared with the unvaccinated animals. Booster immunization with MtbΔ<i>bioA</i> offered no advantage over a single immunization. These experiments demonstrate the vaccinogenic potential of the attenuated <i>M</i>. <i>tuberculosis bioA</i> mutant against tuberculosis.</p></div