Neuropsychological, neuroimaging and autopsy findings of butane encephalopathy.

BACKGROUND: Butane is an aliphatic hydrocarbon used in various commercial products. While numerous reports of sudden cardiac-related deaths from butane inhalation have been described, butane-associated acute encephalopathy has rarely been reported. CASE PRESENTATION: A 38-year-old man presented with cognitive dysfunction after butane gas inhalation. Neuropsychological test results showed impairments in verbal and visual memory, and frontal executive function. Diffusion weighted MRI revealed symmetric high-signal changes in the bilateral hippocampus and globus pallidus. FDG-PET demonstrated decreased glucose metabolism in the bilateral precuneus and occipital areas and the left temporal region. At the 8-month follow-up, he showed still significant deficits in memory and frontal functions. Diffuse cortical atrophy with white matter hyperintensities and extensive glucose hypometabolism were detected on follow-up MRI and FDG-PET, respectively. Brain autopsy demonstrated necrosis and cavitary lesions in the globus pallidus. CONCLUSIONS: Only a few cases of butane encephalopathy have been reported to date. Brain lesions associated with butane encephalopathy include lesions in the bilateral thalamus, insula, putamen, and cerebellum. To the best of our knowledge, this is the first report on bilateral hippocampal and globus pallidal involvement in acute butane encephalopathy. The pathophysiology of central nervous system complications induced by butane intoxication is not yet fully understood. However, the direct toxic effects of butane or anoxic injury secondary to cardiac arrest or respiratory depression have been suggested as possible mechanisms of edematous changes in the brain after butane intoxication.

Surgery-related anxiety on geriatric patients undergoing total knee arthroplasty: a retrospective observational study.

BACKGROUND: The prevalence of anxiety in patients undergoing total knee arthroplasty (TKA) and its association with postoperative functions are well known; however, the levels of anxiety or anxiety-related characteristics are unknown. This study aimed to investigate the prevalence of clinically significant state anxiety in geriatric patients undergoing TKA for osteoarthritis (OA) of the knee and to evaluate the anxiety-related characteristics experienced by these patients pre- and post-operatively. METHODS: This retrospective observational study recruited patients who had undergone TKA for knee OA using general anesthesia between February 2020 and August 2021. The study participants were geriatric patients older than 65 years who had moderate or severe OA. We evaluated patient characteristics including age, sex, body mass index, smoking status, hypertension, diabetes, and cancer. We assessed their levels of anxiety status using the STAI-X which comprises 20-item scales. Clinically meaningful state anxiety was defined as a total score of 52 or higher. An independent Student's t-test was used to determine differences of STAI score between subgroups in terms of patient characteristics. And patients were asked to complete questionnaires, which assessed four areas: (1) the main cause of anxiety; (2) the most helpful factor in overcoming anxiety before surgery; (3) the most helpful factor in reducing anxiety after surgery; and (4) the most anxious moment during the entire process. RESULTS: The mean STAI score of patients who underwent TKA was 43.0 points and 16.4% of patients experienced clinically significant state anxiety. The current smoking status affect STAI score and the proportion of patients with clinically meaningful state anxiety. The most common cause of preoperative anxiety was the surgery itself. Overall, 38% of patients reported that they experienced the greatest level of anxiety when the surgeon had recommended TKA in the outpatient clinic. The trust in the medical staff before surgery and the surgeon's explanations after surgery helped the most in reducing anxiety. CONCLUSIONS: One in six patients before TKA experience clinically meaningful state anxiety, and about 40% of patients experience anxiety from the time they are recommended for surgery. Patients tended to overcome anxiety before TKA through trust in the medical staff, and the surgeon's explanations after surgery was found to be helpful in reducing anxiety.

Crystal structure of multi-functional enzyme FadB from Cupriavidus necator: Non-formation of FadAB complex.

Cupriavidus necator H16 is a gram-negative chemolithoautotrophic bacterium that has been extensively studied for biosynthesis and biodegradation of polyhydroxyalkanoate (PHA) plastics. To improve our understanding of fatty acid metabolism for PHA production, we determined the crystal structure of multi-functional enoyl-CoA hydratase from Cupriavidus necator H16 (CnFadB). The predicted model of CnFadB created by AlphaFold was used to solve the phase problem during determination of the crystal structure of the protein. The CnFadB structure consists of two distinctive domains, an N-terminal enol-CoA hydratase (ECH) domain and a C-terminal 3-hydroxyacyl-CoA dehydrogenase (HAD) domain, and the substrate- and cofactor-binding modes of these two functional domains were identified. Unlike other known FadB enzymes that exist as dimers complexed with FadA, CnFadB functions as a monomer without forming a complex with CnFadA. Small angle X-ray scattering (SAXS) measurement further proved that CnFadB exists as a monomer in solution. The non-sequential action of FadA and FadB in C. necator appears to affect ß-oxidation and PHA synthesis/degradation.

Comparison of Amyloid in Cerebrospinal Fluid, Brain Imaging, and Autopsy in a Case of Progressive Supranuclear Palsy.

Cerebrospinal fluid (CSF) amyloid-beta 1-42 (Aß1-42) and amyloid positron emission tomography (PET) are the 2 main Alzheimer disease amyloid biomarkers that have been validated in neuropathologically confirmed Alzheimer disease cases. Although many studies have shown concordance of amyloid positivity or negativity between CSF Aß1-42 and amyloid PET, several studies also reported discrepancies between these 2 Aß biomarkers. We conducted a comparison of CSF Aß1-42 level, amyloid PET, and autopsy findings in a case with progressive supranuclear palsy in which biomarker acquisition and postmortem pathologic examination were conducted almost at the same time. Our case with antemortem CSF Aß1-42 (+)/amyloid PET (-) who was pathologically confirmed with Aß pathology in the cerebral cortex may indicate CSF Aß1-42 is more sensitive for assessing in vivo Aß than amyloid PET.

Neuropathological findings in a South Korean patient with Perry syndrome.

OBJECTIVE: The Korean patient with Perry syndrome (PS) was the first to come to autopsy. We report a pathologically confirmed patient with PS, and compare to pathological findings of previous literatures. MATERIALS AND METHODS: The patient had a family history of parkinsonism and had a mutation in the DCTN1 gene. After death an autopsy was performed. We analyzed macroscopic and microscopic findings of the patient. RESULTS: There was no prominent cortical atrophy, but microscopy showed severe neuronal loss, microvacuolation, and gliosis in the substantia nigra (SN). We identified transactive response DNA-binding protein 43 (TDP-43)-positive neuronal cytoplasmic inclusions, dystrophic neurites, and glial cytoplasmic inclusions in surviving SN neurons. In addition, some neurofibrillary tangles (NFTs) were also seen in the parahippocampal gyrus. CONCLUSION: The neuropathology, including TDP-43 proteinopathy, is comparable to that reported previously in Caucasian populations. In addition to the stereotypic features of PS, our patient had NFTs in the parahippocampal gyrus, the pathology similar to that is described as primary age-related tauopathy (PART). These observations suggest that comorbid age-related neuropathologic change may also contribute to cognitive impairment in PS.

Structural Basis for Broad Substrate Selectivity of Alcohol Dehydrogenase YjgB from Escherichia coli.

In metabolic engineering and synthetic biology fields, there have been efforts to produce variable bioalcohol fuels, such as isobutanol and 2-phenylethanol, in order to meet industrial demands. YjgB is an aldehyde dehydrogenase from Escherichia coli that shows nicotinamide adenine dinucleotide phosphate (NADP)-dependent broad selectivity for aldehyde derivatives with an aromatic ring or small aliphatic chain. This could contribute to the design of industrial synthetic pathways. We determined the crystal structures of YjgB for both its apo-form and NADP-complexed form at resolutions of 1.55 and 2.00 Å, respectively, in order to understand the mechanism of broad substrate selectivity. The hydrophobic pocket of the active site and the nicotinamide ring of NADP(H) are both involved in conferring its broad specificity toward aldehyde substrates. In addition, based on docking-simulation data, we inferred that π-π stacking between substrates and aromatic side chains might play a crucial role in recognizing substrates. Our structural analysis of YjgB might provide insights into establishing frameworks to understand its broad substrate specificity and develop engineered enzymes for industrial biofuel synthesis.

Early stage memory impairment, visual hallucinations, and myoclonus combined with temporal lobe atrophy predict Alzheimer's disease pathology in corticobasal syndrome.

Corticobasal syndrome (CBS) is a typical phenotype of corticobasal degeneration (CBD). However, autopsy series have shown that many CBS cases emerge from various types of non-CBD pathology. We report a 73-year-old Korean man who was clinically diagnosed with CBS whose underlying pathology was Alzheimer's disease (AD) at autopsy (CBS-AD). This case suggests that early developing memory impairment and myoclonus, severe temporoparietal atrophy, and visual hallucinations may support a more specific prediction of CBS-AD.

Structural insights into the novel ARM-repeat protein CTNNBL1 and its association with the hPrp19-CDC5L complex.

The hPrp19-CDC5L complex plays a crucial role during human pre-mRNA splicing by catalytic activation of the spliceosome. In order to elucidate the molecular architecture of the hPrp19-CDC5L complex, the crystal structure of CTNNBL1, one of the major components of this complex, was determined. Unlike canonical ARM-repeat proteins such as ß-catenin and importin-α, CTNNBL1 was found to contain a twisted and extended ARM-repeat structure at the C-terminal domain and, more importantly, the protein formed a stable dimer. A highly negatively charged patch formed in the N-terminal ARM-repeat domain of CTNNBL1 provides a binding site for CDC5L, a binding partner of the protein in the hPrp19-CDC5L complex, and these two proteins form a complex with a stoichiometry of 2:2. These findings not only present the crystal structure of a novel ARM-repeat protein, CTNNBL1, but also provide insights into the detailed molecular architecture of the hPrp19-CDC5L complex.

Crystal structure and biochemical characterization of beta-keto thiolase B from polyhydroxyalkanoate-producing bacterium Ralstonia eutropha H16.

ReBktB is a ß-keto thiolase from Ralstonia eutropha H16 that catalyzes condensation reactions between acetyl-CoA with acyl-CoA molecules that contains different numbers of carbon atoms, such as acetyl-CoA, propionyl-CoA, and butyryl-CoA, to produce valuable bioproducts, such as polyhydroxybutyrate, polyhydroxybutyrate-hydroxyvalerate, and hexanoate. We solved a crystal structure of ReBktB at 2.3Å, and the overall structure has a similar fold to that of type II biosynthetic thiolases, such as PhbA from Zoogloea ramigera (ZrPhbA). The superposition of this structure with that of ZrPhbA complexed with CoA revealed the residues that comprise the catalytic and substrate binding sites of ReBktB. The catalytic site of ReBktB contains three conserved residues, Cys90, His350, and Cys380, which may function as a covalent nucleophile, a general base, and second nucleophile, respectively. For substrate binding, ReBktB stabilized the ADP moiety of CoA in a distinct way compared to ZrPhbA with His219, Arg221, and Asp228 residues, whereas the stabilization of ß-mercaptoethyamine and pantothenic acid moieties of CoA was quite similar between these two enzymes. Kinetic study of ReBktB revealed that K(m), V(max), and K(cat) values of 11.58 µM, 1.5 µmol/min, and 102.18 s(-1), respectively, and the catalytic and substrate binding sites of ReBktB were further confirmed by site-directed mutagenesis experiments.

The host protease KLK5 primes and activates spike proteins to promote human betacoronavirus replication and lung inflammation.

Coronaviruses rely on host proteases to activate the viral spike protein, which facilitates fusion with the host cell membrane and the release of viral genomic RNAs into the host cell cytoplasm. The distribution of specific host proteases in the host determines the host, tissue, and cellular tropism of these viruses. Here, we identified the kallikrein (KLK) family member KLK5 as a major host protease secreted by human airway cells and exploited by multiple human betacoronaviruses. KLK5 cleaved both the priming (S1/S2) and activation (S2') sites of spike proteins from various human betacoronaviruses in vitro. In contrast, KLK12 and KLK13 displayed preferences for either the S2' or S1/S2 site, respectively. Whereas KLK12 and KLK13 worked in concert to activate SARS-CoV-2 and MERS-CoV spike proteins, KLK5 by itself efficiently activated spike proteins from several human betacoronaviruses, including SARS-CoV-2. Infection of differentiated human bronchial epithelial cells (HBECs) with human betacoronaviruses induced an increase in KLK5 that promoted virus replication. Furthermore, ursolic acid and other related plant-derived triterpenoids that inhibit KLK5 effectively suppressed the replication of SARS-CoV, MERS-CoV, and SARS-CoV-2 in HBECs and mitigated lung inflammation in mice infected with MERS-CoV or SARS-CoV-2. We propose that KLK5 is a pancoronavirus host factor and a promising therapeutic target for current and future coronavirus-induced diseases.

HA N193D substitution in the HPAI H5N1 virus alters receptor binding affinity and enhances virulence in mammalian hosts.

During the 2021/2022 winter season, we isolated highly pathogenic avian influenza (HPAI) H5N1 viruses harbouring an amino acid substitution from Asparagine(N) to Aspartic acid (D) at residue 193 of the hemagglutinin (HA) receptor binding domain (RBD) from migratory birds in South Korea. Herein, we investigated the characteristics of the N193D HA-RBD substitution in the A/CommonTeal/Korea/W811/2021[CT/W811] virus by using recombinant viruses engineered via reverse genetics (RG). A receptor affinity assay revealed that the N193D HA-RBD substitution in CT/W811 increases α2,6 sialic acid receptor binding affinity. The rCT/W811-HA193N virus caused rapid lethality with high virus titres in chickens compared with the rCT/W811-HA193D virus, while the rCT/W811-HA193D virus exhibited enhanced virulence in mammalian hosts with multiple tissue tropism. Surprisingly, a ferret-to-ferret transmission assay revealed that rCT/W811-HA193D virus replicates well in the respiratory tract, at a rate about 10 times higher than that of rCT/W811-HA193N, and all rCT/W811-HA193D direct contact ferrets were seroconverted at 10 days post-contact. Further, competition transmission assay of the two viruses revealed that rCT/W811-HA193D has enhanced growth kinetics compared with the rCT/W811-HA193N, eventually becoming the dominant strain in nasal turbinates. Further, rCT/W811-HA193D exhibits high infectivity in primary human bronchial epithelial (HBE) cells, suggesting the potential for human infection. Taken together, the HA-193D containing HPAI H5N1 virus from migratory birds showed enhanced virulence in mammalian hosts, but not in avian hosts, with multi-organ replication and ferret-to-ferret transmission. Thus, this suggests that HA-193D change increases the probability of HPAI H5N1 infection and transmission in humans.

Crystal Structure of Mesaconyl-CoA Hydratase from Methylorubrum extorquens CM4.

Methylorubrum extorquens, a facultative methylotroph, assimilates C1 compounds and accumulates poly-ß-hydroxylbutyrate (PHB) as carbon and energy sources. The ethylmalonyl pathway is central to the carbon metabolism of M. extorquens, and is linked with a serine cycle and a PHB biosynthesis pathway. Understanding the ethylmalonyl pathway is vital in utilizing methylotrophs to produce value-added chemicals. In this study, we determined the crystal structure of the mesaconyl-CoA hydratase from M. extorquens (MeMeaC) that catalyzes the reversible conversion of mesaconyl-CoA to ß-methylmalyl-CoA. The crystal structure of MeMeaC revealed that the enzyme belongs to the MaoC-like dehydratase domain superfamily and functions as a trimer. In our current MeMeaC structure, malic acid occupied the substrate binding site, which reveals how MeMeaC recognizes the ß-methylmalyl-moiety of its substrate. The active site of the enzyme was further speculated by comparing its structure with those of other MaoC-like hydratases.

Cryo-EM structure of bifunctional malonyl-CoA reductase from Chloroflexus aurantiacus reveals a dynamic domain movement for high enzymatic activity.

The platform chemical 3-hydroxypropionic acid is used to synthesize various valuable materials, including bioplastics. Bifunctional malonyl-CoA reductase is a key enzyme in 3-hydroxypropionic acid biosynthesis as it catalyzes the two-step reduction of malonyl-CoA to malonate semialdehyde to 3-hydroxypropionic acid. Here, we report the cryo-EM structure of a full-length malonyl-CoA reductase protein from Chloroflexus aurantiacus (CaMCRFull). The EM model of CaMCRFull reveals a tandem helix architecture comprising an N-terminal (CaMCRND) and a C-terminal (CaMCRCD) domain. The CaMCRFull model also revealed that the enzyme undergoes a dynamic domain movement between CaMCRND and CaMCRCD due to the presence of a flexible linker between these two domains. Increasing the flexibility and extension of the linker resulted in a twofold increase in enzyme activity, indicating that for CaMCR, domain movement is crucial for high enzyme activity. We also describe the structural features of CaMCRND and CaMCRCD. This study reveals the protein structures underlying the molecular mechanism of CaMCRFull and thereby provides valuable information for future enzyme engineering to improve the productivity of 3-hydroxypropionic acid.

Cloning, expression, purification, crystallization and X-ray crystallographic analysis of Rv3168 from Mycobacterium tuberculosis H37Rv.

Tuberculosis is a widespread and deadly infectious disease, with one third of the human population already being infected. Aminoglycoside antibiotics have become less effective in recent years owing to antibiotic resistance, which arises primarily through enzymatic modification of the antibiotics. The gene product Rv3168, a putative aminoglycoside phosphotransferase (APH), from Mycobacterium tuberculosis was crystallized using the sitting-drop vapour-diffusion method in the presence of 0.2 M calcium acetate, 0.1 M Tris-HCl pH 7.0 and 20% PEG 3000 at 295 K. X-ray diffraction data were collected to a maximum resolution of 1.67 Å on a synchrotron beamline. The crystal belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 56.74, b = 62.37, c = 103.61 Å. With one molecule per asymmetric unit, the crystal volume per unit protein weight (V(M)) is 2.91 Å(3) Da(-1). The structure was solved by the single-wavelength anomalous dispersion method and refinement of the selenomethionine structure is in progress.

Cloning, expression, purification, crystallization and X-ray crystallographic analysis of glucuronic acid dehydrogenase from Chromohalobacter salexigens.

Glucuronic acid dehydrogenase (GluUADH), the product of the Csal-2474 gene from the halophilic bacterium Chromohalobacter salexigens DSM 3043, is an enzyme with potential use in the conversion of glucuronic acid in seaweed biomass to fuels and chemicals. GluUADH is an enzyme that catalyzes the oxidation of glucuronic acid (GluUA) and galacturonic acid (GalUA) and has a preference for NAD(+) rather than NADP(+) as a cofactor. Recombinant GluUADH was crystallized in the presence of 0.2 M calcium acetate, 0.1 M Tris-HCl pH 7.0 and 20% PEG 3000 at 295 K. X-ray diffraction data were collected to a maximum resolution of 2.1 Å. The GluUADH crystal belonged to space group P6(3), with unit-cell parameters a = b = 122.58, c = 150.49 Å, γ = 120°. With one molecule per asymmetric unit, the crystal volume per unit protein weight (V(M)) is 2.78 Å(3) Da(-1). The structure was solved by the single anomalous dispersion method and structure refinement is in progress.

Crystal structure of non-redox regulated SSADH from Escherichia coli.

SSADH is involved in the final step of GABA degradation, converting SSA to succinic acid in the human mitochondrial matrix, and its activity is known to be regulated via 'redox-switch modulation' of the catalytic loop. We present the crystal structure of EcSSADH, revealing that the catalytic loop of EcSSADH, unlike that of human SSADH, does not undergo disulfide bond-mediated structural changes upon changes of environmental redox status. Subsequent redox change experiments using recombinant proteins confirm the non-redox regulation of this protein. Detailed structural analysis shows that a difference in the conformation of the connecting loop (beta15-beta16) causes the formation of a water molecule-mediated hydrogen bond network between the connecting loop and the catalytic loop in EcSSADH, making the catalytic loop of EcSSADH more rigid compared to that of human SSADH. The cytosolic localization of EcSSADH and the cellular function of the GABA shunt in E. coli might result in the non-redox mediated regulatory mechanisms of the protein.

A solvent extraction approach to recover acetic acid from mixed waste acids produced during semiconductor wafer process.

Recovery of acetic acid (HAc) from the waste etching solution discharged from silicon wafer manufacturing process has been attempted by using solvent extraction process. For this purpose 2-ethylhexyl alcohol (EHA) was used as organic solvent. In the pre-treatment stage >99% silicon and hydrofluoric acid was removed from the solution by precipitation. The synthesized product, Na(2)SiF(6) having 98.2% purity was considered of commercial grade having good market value. The waste solution containing 279 g/L acetic acid, 513 g/L nitric acid, 0.9 g/L hydrofluoric acid and 0.030 g/L silicon was used for solvent extraction study. From the batch test results equilibrium conditions for HAc recovery were optimized and found to be 4 stages of extraction at an organic:aqueous (O:A) ratio of 3, 4 stages of scrubbing and 4 stages of stripping at an O:A ratio of 1. Deionized water (DW) was used as stripping agent to elute HAc from organic phase. In the whole batch process 96.3% acetic acid recovery was achieved. Continuous operations were successfully conducted for 100 h using a mixer-settler to examine the feasibility of the extraction system for its possible commercial application. Finally, a complete process flowsheet with material balance for the separation and recovery of HAc has been proposed.

Antimicrobial resistance of Staphylococcus aureus isolated from skin infections and its implications in various clinical conditions in Korea.

BACKGROUND: Periodic investigations into patterns of antimicrobial resistance can help to optimize the efficacy of treatment and limit the development of resistance. OBJECTIVES: The aim of this study was to update information on patterns of antimicrobial resistance in Staphylococcus aureus isolated from skin infections in South Korea. METHODS: We retrospectively analyzed clinical information and in vitro antimicrobial resistance data for 965 clinical S. aureus isolates obtained from skin infections during 2010-2013 in a university hospital in South Korea. RESULTS: The rate of resistance to oxacillin (methicillin-resistant S. aureus [MRSA]) was 47.4%. Similar rates of resistance to erythromycin (45.6%), fusidic acid (44.0%), and clindamycin (42.3%) were noted. The rate of resistance to mupirocin was 8.4%. Overall, 4.9% of isolates were resistant to both fusidic acid and mupirocin. None of the isolates showed resistance to habekacin, synercid, teicoplanin, or vancomycin. Generally, antimicrobial resistance rates did not increase from 2010 to 2013 except with reference to a few agents such as mupirocin and rifampin. Isolates from surgical patients, inpatients, non-dermatology outpatients, and adult patients showed relatively high rates of resistance to multiple antimicrobials. Resistance to mupirocin was not only lower than that to fusidic acid but was consistent across clinical contexts. CONCLUSIONS: The prevalence of MRSA in skin infections in South Korea did not increase during 2010-2013. Isolates from dermatology outpatients showed relatively lower rates of resistance to multiple antimicrobials than isolates from non-dermatology outpatients. Among topical antimicrobials, resistance to mupirocin was relatively low regardless of clinical condition.