Long-term outcomes of patients with autoimmune hepatitis induced cirrhosis after immunosuppressive treatment

INTRODUCTION

Autoimmune hepatitis is an immune-mediated liver disease that results in hepatic inflammation and subsequent fibrosis. We aimed to assess the natural history of autoimmune hepatitis in patients who had cirrhosis at the time of diagnosis.

METHODS

We examined consecutive patients with autoimmune hepatitis (based on the revised International Autoimmune Hepatitis Group criteria) and cirrhosis who had long-term follow-up between 2012 and 2018. Complete clinical data, including longitudinal data, was obtained for each patient to determine clinical and biochemical outcomes. Decompensating events were defined as complications of portal hypertension.

RESULTS

Thirty-four patients presenting with autoimmune hepatitis induced cirrhosis (age 50, 17-81; 71% women) were followed for an average of 8 years post-diagnosis. Fourteen (41%) patients had a decompensating event at diagnosis. All patients were begun on treatment; index decompensating events resolved in all patients. Twenty-six (76%) patients had normalization of transaminases; in this group, 4 (15%) patients developed one or more new decompensating events and 1 patient (4%) died. Of the 8 (24%) patients who did not have transaminase normalization, 6 (75%) developed one or more new decompensating events and 5 (62%) died or underwent liver transplant. There was a significant association between achieving normalization of transaminases and protection from developing a decompensating event ( P  = 0.003) and liver transplant or death ( P  = 0.001).

CONCLUSION

Most patients with autoimmune hepatitis with cirrhosis at presentation achieved normalization of transaminases with treatment and rarely developed further decompensating events. We speculate that some of these patients had stabilization or reversal of portal hypertension.

d-amino acids metabolism reflects the evolutionary origin of higher plants and their adaptation to the environment

d-amino acids are the d stereoisomers of the common l-amino acids found in proteins. Over the past two decades, the occurrence of d-amino acids in plants has been reported and circumstantial evidence for a role in various processes, including interaction with soil microorganisms or interference with cellular signalling, has been provided. However, examples are not numerous and d-amino acids can also be detrimental, some of them inhibiting growth and development. Thus, the persistence of d-amino acid metabolism in plants is rather surprising, and the evolutionary origins of d-amino acid metabolism are currently unclear. Systemic analysis of sequences associated with d-amino acid metabolism enzymes shows that they are not simply inherited from cyanobacterial metabolism. In fact, the history of plant d-amino acid metabolism enzymes likely involves multiple steps, cellular compartments, gene transfers and losses. Regardless of evolutionary steps, enzymes of d-amino acid metabolism, such as d-amino acid transferases or racemases, have been retained by higher plants and have not simply been eliminated, so it is likely that they fulfil important metabolic roles such as serine, folate or plastid peptidoglycan metabolism. We suggest that d-amino acid metabolism may have been critical to support metabolic functions required during the evolution of land plants.

Serum Galectin-3 as a Non-Invasive Marker for Primary Sclerosing Cholangitis

Primary sclerosing cholangitis (PSC) is a serious liver disease associated with inflammatory bowel disease (IBD). Galectin-3, an inflammatory and fibrotic molecule, has elevated circulating levels in patients with chronic liver disease and inflammatory bowel disease (IBD). This study aims to clarify whether galectin-3 can differentiate between patients with IBD, PSC, and PSC-IBD. Our study measured serum galectin-3 levels in 38 healthy controls, 55 patients with IBD, and 22 patients with PSC (11 patients had underlying IBD and 11 patients did not), alongside the urinary galectin-3 of these patients and 18 controls. Serum and urinary galectin-3 levels in IBD patients were comparable to those in controls. Among IBD patients, those with high fecal calprotectin, indicating severe disease, exhibited lower serum and elevated urinary galectin-3 levels compared to those with low calprotectin levels. Serum galectin-3 levels were inversely correlated with C-reactive protein levels. PSC patients displayed higher serum and urinary galectin-3 levels than IBD patients, with the highest serum levels observed in PSC patients with coexisting IBD. There was no correlation between serum and urinary galectin-3 levels and laboratory indicators of liver injury in both IBD and PSC patients. In conclusion, this study demonstrates that serum and urinary galectin-3 levels can distinguish IBD from PSC patients, and also reveals higher serum galectin-3 levels in PSC-IBD patients compared to those with isolated PSC.

Enzymes as indispensable markers in disease diagnosis

Enzymes have been used for disease diagnosis for many decades; however, advancements in technology like ELISA and flow cytometry-based detection have significantly increased their use and have increased the sensitivity of detection. Technological advancements in recombinant enzyme production have increased enzymatic stability, and the use of colorimetric-based and florescence-based assays has led to their increased use as biomarkers for disease detection. Enzymes like acid phosphatase, cathepsin, lactate dehydrogenase, thymidine kinase and creatine kinase are indispensable markers for diagnosing cancer, cardiovascular diseases and others. This minireview summarizes various enzymes used in disease diagnosis, their metabolic role, market value and potential as disease markers across various metabolic and other disorders.

Liver integrity and the risk of Alzheimer's disease and related dementias

INTRODUCTION

We examined midlife (1990-1992, mean age 57) and late-life (2011-2013, mean age 75) nonalcoholic fatty liver disease (NAFLD) and aminotransferase with incident dementia risk through 2019 in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS

We characterized NAFLD using the fatty liver index and fibrosis-4, and we categorized aminotransferase using the optimal equal-hazard ratio (HR) approach. We estimated HRs for incident dementia ascertained from multiple data sources.

RESULTS

Adjusted for demographics, alcohol consumption, and kidney function, individuals with low, intermediate, and high liver fibrosis in midlife (HRs: 1.45, 1.40, and 2.25, respectively), but not at older age, had higher dementia risks than individuals without fatty liver. A U-shaped association was observed for alanine aminotransferase with dementia risk, which was more pronounced in late-life assessment.

DISCUSSION

Our findings highlight dementia burden in high-prevalent NAFLD and the important feature of late-life aminotransaminase as a surrogate biomarker linking liver hypometabolism to dementia. Highlights Although evidence of liver involvement in dementia development has been documented in animal studies, the evidence in humans is limited. Midlife NAFLD raised dementia risk proportionate to severity. Late-life NAFLD was not associated with a high risk of dementia. Low alanine aminotransferase was associated with an elevated dementia risk, especially when measured in late life.

Prediction of severity of dengue infection in children based on hepatic involvement

Background and Aim

To assess the spectrum of hepatic involvement in children with dengue fever (DF) and prediction of severity of dengue infection by early detection of elevated liver enzymes.

Methods

This prospective observational study was conducted at a tertiary care hospital from June 2019 to September 2019. Children admitted with DF were included. Severity of DF was graded as dengue without warning sign (DNWS), with warning sign (DWS), and severe dengue fever (SDF) according to WHO criteria. Liver injury (LI) was defined as alanine aminotransferase (ALT) more than upper limit of normal irrespective of sex.

Results

Of 190 children (male, 109) with DF, 60 had DNWS, 49 had DWS, and 81 had SDF. A total of 100 children (52.6%) had LI. The distribution of hepatic involvement spectrum involves hepatomegaly (26.3%), hepatic tenderness (25.2%), features of acute liver failure (1.5%), raised level of ALT (52.6%), raised level of aspartateaminotransferase (AST) (65.8%), prolonged prothrombin time (7.3%), and reduced level of serum albumin (44.7%) in children. Of them, 5.8% and 6.8% of children had >tenfold increase in ALT and AST values. The degree of liver function derangement significantly (P < 0.05) increased with DF severity. In our study, ALT at 422 IU/L (10 times upper limit of normal [ULN]) and AST 689 IU/L (17 times ULN) had similar sensitivity and specificity as WHO recommended cutoff of 1000 IU/L (25 times of ULN) to detect SDF.

Conclusion

ALT ≥10 times and AST ≥17 times of ULN are as sensitive as ≥25 times (as recommended by WHO) to detect SDF.

Efficacy and Safety of the Natural Killer T Cell-Stimulatory Glycolipid OCH-NCNP1 for Patients With Relapsing Multiple Sclerosis: Protocol for a Randomized Placebo-Controlled Clinical Trial

BACKGROUND

Multiple sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system that causes myelin sheath damage and axonal degeneration. The glycolipid (2S, 3S, 4R)-1-O-(α-d-galactosyl)-2-tetracosanoylamino-1,3,4-nonaetriol (OCH-NCNP1 or OCH) exerts an immunoregulatory action that suppresses T helper (Th)1 cell-mediated immune responses through natural killer T cell activation, selective interleukin-4 production, and Th2 bias induction in human CD4-positive natural killer T cells.

OBJECTIVE

This trial aims to investigate the efficacy and safety of the immunomodulator OCH in patients with relapsing MS through 24-week repeated administration.

METHODS

This protocol describes a double-blind, multicenter, placebo-controlled, randomized phase II clinical trial that was initiated in September 2019. The participants were randomly assigned to either a placebo control group or an OCH-NCNP1 group and the investigational drug (3.0 mg) was orally administered once weekly for the 24-week duration. Major inclusion criteria are as follows: patients had been diagnosed with relapsing MS (relapsing-remitting and/or secondary progressive MS) based on the revised McDonald criteria or were diagnosed with MS by an attending physician as noted in their medical records; patients with at least two medically confirmed clinical exacerbations within 24 months prior to consent or one exacerbation within 12 months prior to consent; patients with at least one lesion suspected to be MS on screening magnetic resonance imaging (MRI); and patients with 7 points or less in the Expanded Disability Status Scale during screening. Major exclusion criteria are as follows: diagnosis of neuromyelitis optica and one of optic neuritis, acute myelitis, and satisfying at least two of the following three items: (1) spinal cord MRI lesion extending across at least three vertebral bodies, (2) no brain MRI lesions during onset (at least four cerebral white matter lesions or three lesions, one of which is around the lateral ventricle), and (3) neuromyelitis optica-immunoglobulin G or antiaquaporin-4 antibody-positive. Outcome measures include the primary outcome of MRI changes (the percentage of subjects with new or newly expanded lesions at 24 weeks on T2-weighted MRI) and the secondary outcomes annual relapse rate (number of recurrences per year), relapse-free period (time to recurrence), sustained reduction in disability (SRD) occurrence rate, period until SRD (time to SRD occurrence), no evidence of disease activity, and exploratory biomarkers from phase I trials (such as gene expression, cell frequency, and intestinal and oral microbiome).

RESULTS

We plan to enroll 30 patients in the full analysis set. Enrollment was closed in June 2021 and the study analysis was completed in March 2023.

CONCLUSIONS

This randomized controlled trial will determine whether OCH-NCNP1 is effective and safe in patients with MS as well as provide evidence for the potential of OCH-NCNP1 as a therapeutic agent for MS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04211740; https://clinicaltrials.gov/study/NCT04211740.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/46709.

Transaminases Provide Key Chiral Building Blocks for the Synthesis of Selective M1/M4 Agonists

We have developed a chiral route toward the synthesis of muscarinic M4 agonists that was enabled by the biocatalytic synthesis of the key spirocyclic diamine building blocks 10 and 12. Using these bifunctional compounds we were able to optimize a synthetic sequence toward a collection of advanced intermediates for further elaboration. These advanced intermediates were then used as starting points for early medicinal chemistry and the identification of selective M1/M4 agonists.

High-Resolution Structural Proteomics of Mitochondria Using the 'Build and Retrieve' Methodology

The application of integrated systems biology to the field of structural biology is a promising new direction, although it is still in the infant stages of development. Here we report the use of single particle cryo-EM to identify multiple proteins from three enriched heterogeneous fractions prepared from human liver mitochondrial lysate. We simultaneously identify and solve high-resolution structures of nine essential mitochondrial enzymes with key metabolic functions, including fatty acid catabolism, reactive oxidative species clearance, and amino acid metabolism. Our methodology also identified multiple distinct members of the acyl-CoA dehydrogenase family. This work highlights the potential of cryo-EM to explore tissue proteomics at the atomic level.

Distinctive biochemistry profiles associated with hyperuricemia between Tibetans and Hans in China

Purpose

We sought to identify distinct risk factors for hyperuricemia in native Tibetan and immigrant Han populations in Tibet, China.

Methods

Three cohorts of male participants aged between 20 and 40 years were enrolled in this study. Biochemical parameters including serum uric acid (UA), fasting plasma glucose, insulin, lactate dehydrogenase (LDH), thyroxin, blood cell count, aminotransferase, and lipid profiles were analyzed. The association of risk factors with UA levels was evaluated using a multivariable line regression model. The effect of UA level on the biochemical parameters between the Hans and Tibetans was evaluated by two-way ANOVA.

Results

The prevalence of hyperuricemia (≥420 μmol/L) was 24.8% (62/250) in the Hans, similar to 23.8% (29/136) in the Tibetans. In the regression analysis, the risk factors that were significantly associated with UA in Hans did not apply to Tibetans. Tibetans had higher fasting insulin (P<0.05) and LDH (P<0.01) levels, in contrast with lower levels of triglycerides (P<0.05), total cholesterol (P<0.01), and low-density lipoprotein-cholesterol (P<0.01) than Hans in normal UA populations. Biochemistry analysis revealed lower albumin levels (P<0.001) and higher levels of all aminotransaminase and especially alkaline phosphatase (P<0.01) in Tibetans than in Hans in both populations. Compared with Hans, Tibetans had lower serum levels of urea, creatinine, and electrolytes in the normal UA population, which were further exacerbated in the high UA population. Tibetans had comparable white blood cell counts as Hans in both normal and high UA populations. In contrast, the red blood cell count and hemoglobin concentration were much lower in Tibetans than in Hans under high UA conditions.

Conclusions

The distinctive biochemistry between Tibetans and Hans may underlie the different etiologies of hyperuricemia in Tibet, China.

Structural and Mechanistic Basis for the Inactivation of Human Ornithine Aminotransferase by (3S,4S)-3-Amino-4-fluorocyclopentenecarboxylic Acid

Ornithine aminotransferase (OAT) is overexpressed in hepatocellular carcinoma (HCC), and we previously showed that inactivation of OAT inhibits the growth of HCC. Recently, we found that (3S,4S)-3-amino-4-fluorocyclopentenecarboxylic acid (5) was a potent inactivator of γ-aminobutyric acid aminotransferase (GABA-AT), proceeding by an enamine mechanism. Here we describe our investigations into the activity and mechanism of 5 as an inactivator of human OAT. We have found that 5 exhibits 10-fold less inactivation efficiency (kinact/KI) against hOAT than GABA-AT. A comprehensive mechanistic study was carried out to understand its inactivation mechanism with hOAT. pKa and electrostatic potential calculations were performed to further support the notion that the α,β-unsaturated alkene of 5 is critical for enhancing acidity and nucleophilicity of the corresponding intermediates and ultimately responsible for the improved inactivation efficiency of 5 over the corresponding saturated analogue (4). Intact protein mass spectrometry and the crystal structure complex with hOAT provide evidence to conclude that 5 mainly inactivates hOAT through noncovalent interactions, and that, unlike with GABA-AT, covalent binding with hOAT is a minor component of the total inhibition which is unique relative to other monofluoro-substituted derivatives. Furthermore, based on the results of transient-state measurements and free energy calculations, it is suggested that the α,β-unsaturated carboxylate group of PLP-bound 5 may be directly involved in the inactivation cascade by forming an enolate intermediate. Overall, compound 5 exhibits unusual structural conversions which are catalyzed by specific residues within hOAT, ultimately leading to an enamine mechanism-based inactivation of hOAT through noncovalent interactions and covalent modification.

Investigation of the enzymes required for the biosynthesis of 2,3-diacetamido-2,3-dideoxy-d-glucuronic acid in Psychrobacter cryohalolentis K5T

Psychrobacter cryohalolentis K5T is a Gram-negative bacterium first isolated from Siberian permafrost in 2006. It has a complex O-antigen containing l-rhamnose, d-galactose, two diacetamido-sugars, and one triacetamido-sugar. The biosynthetic pathway for one of the diacetamido-sugars, namely 2,3-diacetamido-2,3-dideoxy-d-glucuronic acid, is presently unknown. Utilizing the published genome sequence of P. cryohalolentis K5T , we hypothesized that the genes designated Pcryo_0613, Pcryo_0614, Pcryo_0616, and Pcryo_0615 encode for a uridine dinucleotide (UDP)-N-acetyl-d-glucosamine 6-dehydrogenase, an nicotinamide adenine dinucleotide (oxidized) (NAD+ )-dependent dehydrogenase, a pyridoxal 5'-phosphate (PLP)-dependent aminotransferase, and an N-acetyltransferase, respectively, activities of which would be required for the biosynthesis of this unusual carbohydrate. Here we present the cloning, overexpression, and purification of these hypothetical proteins. Kinetic data on the enzymes encoded by Pcryo_0613, Pcryo_0614, and Pcryo_0615 confirmed their postulated biochemical activities. In addition, the high-resolution X-ray structures of both the internal and external aldimine forms of the aminotransferase were determined to 1.25 and 1.0 Å, respectively. Finally, the three-dimensional architecture of the N-acetyltransferase in complex with its substrate and coenzyme A was solved to 1.8 Å resolution. Strikingly, the N-acetyltransferase was shown to adopt a new motif for UDP-sugar binding. The data presented herein provide additional insight into sugar biosynthesis in Gram-negative bacteria.

Association between different patterns of shift work and liver function tests: A cross-sectional analysis of Shahedieh PERSIAN cohort data, Iran, 2020

BACKGROUND

Recent studies suggest that shift work may cause liver dysfunction.

OBJECTIVE

This study aimed to examine the relationship between different patterns of shift work and elevated level of liver enzymes.

METHODS

In this cross-sectional study, 1910 workers aged 35 to 70 years were selected with simple random sampling from 9978 participants of the recruitment phase of Shahedieh PERSIAN cohort study. Level of serum liver enzymes (ALT, AST, ALP, and GGT) and ALT/AST ratio was compared between shift workers and non-shift workers, and among employees working in different patterns of shift work. Data were analyzed by SPSS (version 21.0) using Student's T test, Mann-Whitney U test, chi-square test, Kruskal Wallis test, and logistic regression.

RESULTS

Among 1347 males (71%) and 563 females (29%) with a mean age of 40.4±7.4 years, 469 were shift workers. Fixed evening type shift was the most common (30.3%) and fixed night-shift was the least common (0.9%) type of shift work. The mean blood levels of liver enzymes was not significantly different between shift workers and non-shift workers. In comparison between different patterns of shift work, the mean serum level of GGT was significantly higher in individuals with slow rotating shifts than those with fixed evening shifts, rapid rotating, split and fixed 24 hour shifts (p≤0.001). After adjusting for confounding factors only elevated AST was significantly higher in shift workers.

CONCLUSION

There was only a significant association between shift work and elevated AST, and no relationship was found with ALT, ALP, GGT, and ALT/AST ratio.

The aminotransferase Aat initiates 3-phenyllactic acid biosynthesis in Pediococcus acidilactici

The function of the aminotransferase Aat (GenBank Protein WP_159211138) from Pediococcus acidilactici FAM 18098 was studied in vivo. For this purpose, the gene was replaced with an erythromycin resistance gene using the temperature-sensitive Escherichia coli-Pediococcus shuttle plasmid pSET4T_Δaat. The knockout was verified by PCR and genome sequencing. Subsequently, the differences between the metabolism of the knockout and of the wild-type strain were investigated by determining the free amino acids and organic acids in culture supernatants. It was found that the knockout mutant no longer synthesized 3-phenyllactic acid (PLA) and 4-hydroxyphenyllactic acid (HPLA). Additionally, the mutant strain no longer catabolized phenylalanine. Metabolic pathway analysis using the KEGG database indicate that P. acidilactici cannot synthesize α-ketoglutarate that is a predominant amino-group acceptor in many transamination reactions. To study the transfer of the amino group of phenylalanine, the wild-type strain was incubated with [¹⁵N] phenylalanine. Mass spectrometry showed that during fermentation, [¹⁵N] alanine was formed, indicating that pyruvic acid is an amino group acceptor in P. acidilactici. The present study shows that Aat plays a crucial role in PLA/HPLA biosynthesis and pyruvic acid is an amino acceptor in transamination reactions in P. acidilactici.

Biochemical and genetic examination of two aminotransferases from the hyperthermophilic archaeon Thermococcus kodakarensis

The hyperthermophilic archaeon Thermococcus kodakarensis utilizes amino acids as a carbon and energy source. Multiple aminotransferases, along with glutamate dehydrogenase, are presumed to be involved in the catabolic conversion of amino acids. T. kodakarensis harbors seven Class I aminotransferase homologs on its genome. Here we examined the biochemical properties and physiological roles of two Class I aminotransferases. The TK0548 protein was produced in Escherichia coli and the TK2268 protein in T. kodakarensis. Purified TK0548 protein preferred Phe, Trp, Tyr, and His, and to a lower extent, Leu, Met and Glu. The TK2268 protein preferred Glu and Asp, with lower activities toward Cys, Leu, Ala, Met and Tyr. Both proteins recognized 2-oxoglutarate as the amino acceptor. The TK0548 protein exhibited the highest k _cat/K _m value toward Phe, followed by Trp, Tyr, and His. The TK2268 protein exhibited highest k _cat/K _m values for Glu and Asp. The TK0548 and TK2268 genes were individually disrupted, and both disruption strains displayed a retardation in growth on a minimal amino acid medium, suggesting their involvement in amino acid metabolism. Activities in the cell-free extracts of the disruption strains and the host strain were examined. The results suggested that the TK0548 protein contributes to the conversion of Trp, Tyr and His, and the TK2268 protein to that of Asp and His. Although other aminotransferases seem to contribute to the transamination of Phe, Trp, Tyr, Asp, and Glu, our results suggest that the TK0548 protein is responsible for the majority of aminotransferase activity toward His in T. kodakarensis. The genetic examination carried out in this study provides insight into the contributions of the two aminotransferases toward specific amino acids in vivo, an aspect which had not been thoroughly considered thus far.

Molecular basis and functional development of enzymes related to amino acid metabolism

Enzymology, the study of enzyme structures and reaction mechanisms can be considered a classical discipline. However, enzymes cannot be freely designed to catalyze desired reactions yet, and enzymology is by no means a complete science. I have long studied the reaction mechanisms of enzymes related to amino acid metabolism, such as aminotransferases and racemases, which depend on pyridoxal 5'-phosphate, a coenzyme form of vitamin B6. During these studies, I have often been reminded that enzymatic reactions are extremely sophisticated processes based on chemical principles and enzyme structures, and have often been amazed at the evolutionary mechanisms that bestowed them with such structures. In this review, I described the reaction mechanism of various pyridoxal enzymes especially related to D-amino acids metabolism, whose roles in mammals have recently attracted attention. I hope to convey some of the significance and interest in enzymology through this review.

Elevated AST/ALT ratio is associated with all-cause mortality and cancer incident

Background

The aspartate transaminase (AST)‐to‐alanine aminotransferase (ALT) ratio, which is used to measure liver injury, has been found to be associated with some chronic diseases and mortality. However, its relevance to cancer incidence resulting from population‐based prospective studies has rarely been reported. In this study, we investigated the correlation of the AST/ALT ratio as a possible predictor of mortality and cancer incidence.

Methods

A total of 9,946 participants fulfilled the inclusion criteria for a basic public health service project of the Health Checkup Program conducted by the BaiYun Community Health Service Center, Taizhou. Deceased participants and cancer incident cases were from The Taizhou Chronic Disease Information Management System. Odds ratios (ORs) and interval of quartile range (IQR) computed by logistic regression analysis and cumulative incidence rate were calculated by the Kaplan–Meier survival method and compared with log‐rank test statistics.

Results

Serum ALT and AST levels were both increased in patients with chronic diseases, but the ratio of AST/ALT was generally decreased. The cancer incident cases (488 new cases) had a greater baseline ratio (median =1.23, IQR: 0.96–1.54) than noncancer cases (median =1.15, IQR: 0.91–1.44). Compared to the first quartile of the AST/ALT ratio, the population in the top quartile had a higher cumulative cancer incidence rate (7.54% vs. 4.44%) during follow‐up period. Furthermore, an elevated AST/ALT ratio increased the risk of all‐cause mortality.

Conclusions

The ratio of AST/ALT is a potential biomarker to assess healthy conditions and long‐term mortality. Especially for cancer, the AST/ALT ratio not only increases at baseline but also predicts the future development of cancer. The clinical value and potential mechanism deserve further research.

Nitrogen Metabolism in Pseudomonas putida: Functional Analysis Using Random Barcode Transposon Sequencing

Pseudomonas putida KT2440 has long been studied for its diverse and robust metabolisms, yet many genes and proteins imparting these growth capacities remain uncharacterized. Using pooled mutant fitness assays, we identified genes and proteins involved in the assimilation of 52 different nitrogen containing compounds. To assay amino acid biosynthesis, 19 amino acid drop-out conditions were also tested. From these 71 conditions, significant fitness phenotypes were elicited in 672 different genes including 100 transcriptional regulators and 112 transport-related proteins. We divide these conditions into 6 classes, and propose assimilatory pathways for the compounds based on this wealth of genetic data. To complement these data, we characterize the substrate range of three promiscuous aminotransferases relevant to metabolic engineering efforts in vitro. Furthermore, we examine the specificity of five transcriptional regulators, explaining some fitness data results and exploring their potential to be developed into useful synthetic biology tools. In addition, we use manifold learning to create an interactive visualization tool for interpreting our BarSeq data, which will improve the accessibility and utility of this work to other researchers. IMPORTANCE Understanding the genetic basis of P. putida's diverse metabolism is imperative for us to reach its full potential as a host for metabolic engineering. Many target molecules of the bioeconomy and their precursors contain nitrogen. This study provides functional evidence linking hundreds of genes to their roles in the metabolism of nitrogenous compounds, and provides an interactive tool for visualizing these data. We further characterize several aminotransferases, lactamases, and regulators, which are of particular interest for metabolic engineering.

Alanine aminotransferase to aspartate aminotransferase ratio and hepatitis B virus on metabolic syndrome: a community-based study

BACKGROUND

The serum aminotransferase elevation in metabolic syndrome (MetS) reflected hepatosteatosis, but there is a conflict with the coexistence of viral hepatitis, especially for the hepatitis B virus (HBV). Thus, this study aimed to investigate the relationship between the alanine aminotransferase (ALT)/aspartate aminotransferase (AST) ratio, MetS, and HBV infection in a rural Taiwanese population.

METHODS

We conducted a cross-sectional analysis in southern Taiwan between March and December 2019. Multivariable logistic regression analyses adjusted for demographics, education, dietary behaviors, irregular exercise, substance use, and viral markers were performed to investigate the association between the ALT/AST ratio and MetS.

RESULTS

Altogether, 2,416 participants (891 men and 1,525 women; mean age, 64.1 ± 14.9 years) were enrolled. Of the participants, 22.7% (n = 519) were seropositive for viral hepatitis. In the multivariable analysis, age [odds ratio (OR) 1.02, 95% CI 1.01-1.03, p < 0.001], ALT/AST ratio >1 (OR 2.63, 95% CI 2.15-3.21, p < 0.001), education (OR 0.96, 95% CI 0.94-0.98, p < 0.001), and HBV seropositivity (OR 0.70, 95% CI 0.52-0.95, p = 0.021) were associated with the risk of MetS. The area under the curve of the ALT/AST ratio was 0.62 (95% CI 0.60-0.64, p < 0.001), and the cutoff value was >0.852 for the Youden index.

CONCLUSION

An ALT/AST ratio >1 could be a simple index for MetS prediction during community checkups. In contrast to age and betel nut chewing, HBV seropositivity and higher education might be inversely associated with MetS. Aggressive health promotion for MetS prevention has emerged as essential in participants without HBV and with lower education levels. Further large-scale, longitudinal studies are needed to unlink these correlations.

Statins in Non-alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the primary cause of chronic liver disease. The range is extensive, including hepatocellular carcinoma, cirrhosis, fibrosis, fatty liver, and non-alcoholic steatohepatitis (NASH). NASH is a condition related to obesity, overweight, metabolic syndrome, diabetes, and dyslipidemia. It is a dynamic condition that can regress to isolated steatosis or progress to fibrosis and cirrhosis. Statins exert anti-inflammatory, proapoptotic, and antifibrotic effects. It has been proposed that these drugs could have a relevant role in NASH. In this review, we provide an overview of current evidence, from mechanisms of statins involved in the modulation of NASH to human trials about the use of statins to treat or attenuate NASH.

Characterization of C-26 aminotransferase, indispensable for steroidal glycoalkaloid biosynthesis

Steroidal glycoalkaloids (SGAs) are toxic specialized metabolites found in members of the Solanaceae, such as Solanum tuberosum (potato) and Solanum lycopersicum (tomato). The major potato SGAs are α-solanine and α-chaconine, which are biosynthesized from cholesterol. Previously, we have characterized two cytochrome P450 monooxygenases and a 2-oxoglutarate-dependent dioxygenase that function in hydroxylation at the C-22, C-26 and C-16α positions, but the aminotransferase responsible for the introduction of a nitrogen moiety into the steroidal skeleton remains uncharacterized. Here, we show that PGA4 encoding a putative γ-aminobutyrate aminotransferase is involved in SGA biosynthesis in potatoes. The PGA4 transcript was expressed at high levels in tuber sprouts, in which SGAs are abundant. Silencing the PGA4 gene decreased potato SGA levels and instead caused the accumulation of furostanol saponins. Analysis of the tomato PGA4 ortholog, GAME12, essentially provided the same results. Recombinant PGA4 protein exhibited catalysis of transamination at the C-26 position of 22-hydroxy-26-oxocholesterol using γ-aminobutyric acid as an amino donor. Solanum stipuloideum (PI 498120), a tuber-bearing wild potato species lacking SGA, was found to have a defective PGA4 gene expressing the truncated transcripts, and transformation of PI 498120 with functional PGA4 resulted in the complementation of SGA production. These findings indicate that PGA4 is a key enzyme for transamination in SGA biosynthesis. The disruption of PGA4 function by genome editing will be a viable approach for accumulating valuable steroidal saponins in SGA-free potatoes.

Serum biomarkers of isoniazid-induced liver injury: Aminotransferases are insufficient, and OPN, L-FABP and HMGB1 can be promising novel biomarkers

Isoniazid (INH)-induced liver injury is a great challenge for tuberculosis treatment. Existing biomarkers cannot accurately determine the occurrence of this injury in the early stage. Therefore, developing early specific sensitive biomarkers of INH-induced liver injury is urgent. A rat model of liver injury was established with gastric infusion of INH or INH plus rifampicin (RFP). We examined seven potential novel serum biomarkers, namely, glutamate dehydrogenase (GLDH), liver-fatty acid-binding protein (L-FABP), high-mobility group box-1 (HMGB1), macrophage colony-stimulating factor receptor (MCSF1R), osteopontin (OPN), total cytokeratin 18 (K18), and caspase-cleaved cytokeratin-18 (ccK18), to evaluate their sensitivity and specificity on INH-induced liver injury. With the increase of drug dosage, combining with RFP and prolonging duration of administration, the liver injury was aggravated, showing as decreased weight of the rats, upgraded liver index and oxidative stress level, and histopathological changes of liver becoming marked. But the activity of serum aminotransferases decreased significantly. The area under the curve (AUC) of receiver-operating characteristic (ROC) curve of OPN, L-FABP, HMGB1, MCSF1R, and GLDH was 0.88, 0.87, 0.85, 0.71, and 0.70 (≥0.7), respectively, and 95% confidence interval of them did not include 0.5, with statistical significance, indicating their potential abilities to become biomarkers of INH-induced liver injury. In conclusion, we found traditional biomarkers ALT and AST were insufficient to discover the INH-induced liver injury accurately and OPN, L-FABP, and HMGB1 can be promising novel biomarkers.

Lessons in clinical reasoning ‒ pitfalls, myths, and pearls: a case of confusion, disequilibrium, and "picking at the air"

OBJECTIVES

Defects in human cognition commonly result in clinical reasoning failures that can lead to diagnostic errors.

CASE PRESENTATION

A 43-year-old female was brought to the emergency department with 4-5 days of confusion, disequilibrium resulting in several falls, and hallucinations. Further investigation revealed tachycardia, diaphoresis, mydriatic pupils, incomprehensible speech and she was seen picking at the air. Given multiple recent medication changes, there was initial concern for serotonin syndrome vs. an anticholinergic toxidrome. She then developed a fever, marked leukocytosis, and worsening encephalopathy. She underwent lumbar puncture and aspiration of an identified left ankle effusion. Methicillin sensitive staph aureus (MSSA) grew from blood, joint, and cerebrospinal fluid cultures within 18 h. She improved with antibiotics and incision, drainage, and washout of her ankle by orthopedic surgery.

CONCLUSIONS

Through integrated commentary on the diagnostic reasoning process from clinical reasoning experts, this case underscores how multiple cognitive biases can cascade sequentially, skewing clinical reasoning toward erroneous conclusions and driving potentially inappropriate testing and treatment. A fishbone diagram is provided to visually demonstrate the major factors that contributed to the diagnostic error. A case discussant describes the importance of structured reflection, a tool to promote metacognitive analysis, and the application of knowledge organization tools such as illness scripts to navigate these cognitive biases.

Investigation of the enzymes required for the biosynthesis of an unusual formylated sugar in the emerging human pathogen Helicobacter canadensis

It is now well established that the Gram-negative bacterium, Helicobacter pylori, causes gastritis in humans. In recent years, it has become apparent that the so-called non-pylori Helicobacters, normally infecting pigs, cats, and dogs, may also be involved in human pathology via zoonotic transmission. Indeed, more than 30 species of non-pylori Helicobacters have been identified thus far. One such organism is Helicobacter canadensis, an emerging pathogen whose genome sequence was published in 2009. Given our long-standing interest in the biosynthesis of N-formylated sugars found in the O-antigens of some Gram-negative bacteria, we were curious as to whether H. canadensis produces such unusual carbohydrates. Here, we demonstrate using both biochemical and structural techniques that the proteins encoded by the HCAN_0198, HCAN_0204, and HCAN_0200 genes in H. canadensis, correspond to a 3,4-ketoisomerase, a pyridoxal 5'-phosphate aminotransferase, and an N-formyltransferase, respectively. For this investigation, five high-resolution X-ray structures were determined and the kinetic parameters for the isomerase and the N-formyltransferase were measured. Based on these data, we suggest that the unusual sugar, 3-formamido-3,6-dideoxy-d-glucose, will most likely be found in the O-antigen of H. canadensis. Whether N-formylated sugars found in the O-antigen contribute to virulence is presently unclear, but it is intriguing that they have been observed in such pathogens as Francisella tularensis, Mycobacterium tuberculosis, and Brucella melitensis.