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International Journal of Medical... Jun 2024Staphylococcus aureus is a notorious pathogen responsible for various severe diseases. Due to the emergence of drug-resistant strains, the prevention and treatment of S....
Staphylococcus aureus is a notorious pathogen responsible for various severe diseases. Due to the emergence of drug-resistant strains, the prevention and treatment of S. aureus infections have become increasingly challenging. Vancomycin is considered to be one of the last-resort drugs for treating most methicillin-resistant S. aureus (MRSA), so it is of great significance to further reveal the mechanism of vancomycin resistance. VraFG is one of the few important ABC (ATP-binding cassette) transporters in S. aureus that can form TCS (two-component systems)/ABC transporter modules. ABC transporters can couple the energy released from ATP hydrolysis to translocate solutes across the cell membrane. In this study, we obtained a strain with decreased vancomycin susceptibility after serial passaging and selection. Subsequently, whole-genome sequencing was performed on this laboratory-derived strain MWA2 and a novel single point mutation was discovered in vraF gene, leading to decreased sensitivity to vancomycin and daptomycin. Furthermore, the mutation reduces autolysis of S. aureus and downregulates the expression of lytM, isaA, and atlA. Additionally, we observed that the mutant has a less net negative surface charge than wild-type strain. We also noted an increase in the expression of the dlt operon and mprF gene, which are associated with cell surface charge and serve to hinder the binding of cationic peptides by promoting electrostatic repulsion. Moreover, this mutation has been shown to enhance hemolytic activity, expand subcutaneous abscesses, reflecting an increased virulence. This study confirms the impact of a point mutation of VraF on S. aureus antibiotic resistance and virulence, contributing to a broader understanding of ABC transporter function and providing new targets for treating S. aureus infections.
Topics: Virulence; Staphylococcal Infections; Anti-Bacterial Agents; Vancomycin; Animals; ATP-Binding Cassette Transporters; Bacterial Proteins; Staphylococcus aureus; Microbial Sensitivity Tests; Vancomycin Resistance; Whole Genome Sequencing; Daptomycin; Mice; Autolysis; Humans; Point Mutation; Mutation; Female
PubMed: 38838390
DOI: 10.1016/j.ijmm.2024.151624 -
Frontiers in Veterinary Science 2024Death initiates a cascade of physiological and biochemical alterations in organs and tissues, resulting in microscopic changes that challenge the histopathological...
Death initiates a cascade of physiological and biochemical alterations in organs and tissues, resulting in microscopic changes that challenge the histopathological evaluation. Moreover, the brain is particularly susceptible to artifacts owing to its unique composition and its location within the cranial vault. The aim of this study was to compile and illustrate the microscopic changes in the central nervous system (CNS) of rats subjected to delayed postmortem fixation. It also scrutinizes the influence of exsanguination and cooling methods on the initiation and progression of these alterations. Twenty-four Wistar Han outbred rats (RccHan: WIST) were sacrificed and stored either at room temperature (18-22°C) or under refrigeration (2-4°C). Necropsies were conducted at different time points postmortem (i.e., 0.5 h, 1 h, 4 h, 8 h, 12 h, 24 h, 36 h, 48 h, 7 days and 14 days). Brain sections underwent simultaneous digital evaluation by 14 pathologists until a consensus was reached on terminology, key findings, and intensity levels. Microscopic observations varied among cell types. Glial cells were similarly affected throughout the CNS and showed pericellular halo, chromatin condensation and nuclear shrinkage. Neurons showed two types of postmortem changes as most of them showed progressive shrinkage, cytoplasmic dissolution and karyorrhexis whereas others acquired a dark-neuron-like appearance. Neuronal changes showed marked differences among neuroanatomical locations. Additional postmortem changes encompassed: granulation and microcavitation in neuropil and white matter; retraction spaces; detachment of ependyma, choroid plexus, and leptomeninges. Severity of findings after 48 h at room temperature was higher than after seven days under refrigeration and similar to or slightly lower than after 14 days under refrigeration. No clear differences were observed related to the sex or weight of the animals or their exsanguination status. This work elucidates the onset and progression of autolytic changes in the brains of Wistar Han rats, offering insights to accurately identify and enhance the histopathological evaluation.
PubMed: 38835889
DOI: 10.3389/fvets.2024.1378609 -
Journal of Veterinary Science May 2024In veterinary forensic science, accurately determining the postmortem interval (PMI) is crucial for identifying the causes of animal deaths. Autolysis, a significant...
IMPORTANCE
In veterinary forensic science, accurately determining the postmortem interval (PMI) is crucial for identifying the causes of animal deaths. Autolysis, a significant postmortem process, influences PMI estimation, but its relationship with humidity is not well understood.
OBJECTIVE
This study aimed to improve the accuracy of PMI estimates in veterinary forensic cases by looking into how different humidity levels affect autolysis in different organs of rats.
METHODS
The study involved 38 male rats, examining histopathological changes in their heart, liver, and pancreas. These organs were subjected to controlled humidity levels (20%, 55%, and 80%) at a constant 22°C. Tissue samples were collected at several intervals (0 h, 12 h, 24 h, 3 days, and 8 days) for comprehensive analysis.
RESULTS
Distinct autolytic characteristics in animal organs emerged under varying humidity conditions. The low-humidity environment rapidly activated autolysis more than the high-humidity environment. In addition, it was found that lower humidity caused nuclear pyknosis, cytoplasmic disintegration, and myofiber interruption. The liver, in particular, showed portal triad aggregation and hepatocyte individuation. The pancreas experienced cell fragmentation and an enlarged intracellular space. High humidity also caused the loss of striations in cardiac tissues, and the liver showed vacuolation. Under these conditions, the pancreas changed eosinophilic secretory granules.
CONCLUSIONS AND RELEVANCE
The study successfully established a clear connection between the autolytic process in PMIs and relative humidity. These findings are significant for developing a more accurate and predictable method for PMI estimation in the field of veterinary forensic science.
Topics: Animals; Humidity; Male; Postmortem Changes; Rats; Liver; Pancreas; Myocardium; Rats, Sprague-Dawley; Autolysis
PubMed: 38834504
DOI: 10.4142/jvs.23327 -
Free Neuropathology Jan 2024
The presence of shrunken neurons with pyknotic nuclei in the dentate nucleus is a common postmortem change associated with autolysis of the cerebellar granular cell layer.
PubMed: 38803422
DOI: 10.17879/freeneuropathology-2024-5398 -
Archives of Pathology & Laboratory... May 2024The National Institutes of Health Genotype-Tissue Expression (GTEx) project was developed to elucidate how genetic variation influences gene expression in multiple...
CONTEXT.—
The National Institutes of Health Genotype-Tissue Expression (GTEx) project was developed to elucidate how genetic variation influences gene expression in multiple normal tissues procured from postmortem donors.
OBJECTIVE.—
To provide critical insight into a biospecimen's suitability for subsequent analysis, each biospecimen underwent quality assessment measures that included evaluation for underlying disease and potential effects introduced by preanalytic factors.
DESIGN.—
Electronic images of each tissue collected from nearly 1000 postmortem donors were evaluated by board-certified pathologists for the extent of autolysis, tissue purity, and the type and abundance of any extraneous tissue. Tissue-specific differences in the severity of autolysis and RNA integrity were evaluated, as were potential relationships between these markers and the duration of postmortem interval and rapidity of death.
RESULTS.—
Tissue-specific challenges in the procurement and preservation of the nearly 30 000 tissue specimens collected during the GTEx project are summarized. Differences in the degree of autolysis and RNA integrity number were observed among the 40 tissue types evaluated, and tissue-specific susceptibilities to the duration of postmortem interval and rapidity of death were observed.
CONCLUSIONS.—
Ninety-five percent of tissues were of sufficient quality to support RNA sequencing analysis. Biospecimens, annotated whole slide images, de-identified clinical data, and genomic data generated for GTEx represent a high-quality and comprehensive resource for the scientific community that has contributed to its use in approximately 1695 articles. Biospecimens and data collected under the GTEx project are available via the GTEx portal and authorized access to the Database of Genotypes and Phenotypes; procedures and whole slide images are available from the National Cancer Institute.
PubMed: 38797720
DOI: 10.5858/arpa.2023-0467-OA -
Foods (Basel, Switzerland) May 2024Yeast, crucial in beer production, holds great potential owing to its ability to transform into a valuable by-product resource, known as brewer's spent yeast (BSY), with...
Yeast, crucial in beer production, holds great potential owing to its ability to transform into a valuable by-product resource, known as brewer's spent yeast (BSY), with potentially beneficial physiological effects. This study aimed to compare the composition and soluble polysaccharide content of Brewer's spent yeast with those of cultured yeast strains, namely (SC) and . (SB), to facilitate the utilization of BSY as an alternative source of functional polysaccharides. BSY exhibited significantly higher carbohydrate content and lower crude protein content than SC and SB cells. The residues recovered through autolysis were 53.11%, 43.83%, and 44.99% for BSY, SC, and SB, respectively. Notably, the polysaccharide content of the BSY residue (641.90 μg/mg) was higher than that of SC (553.52 μg/mg) and SB (591.56 μg/mg). The yields of alkali-extracted water-soluble polysaccharides were 33.62%, 40.76%, and 42.97% for BSY, SC, and SB, respectively, with BSY comprising a comparable proportion of water-soluble saccharides made with SC and SB, including 49.31% mannan and 20.18% β-glucan. Furthermore, BSY demonstrated antioxidant activities, including superoxide dismutase (SOD), ABTS, and DPPH scavenging potential, suggesting its ability to mitigate oxidative stress. BSY also exhibited a significantly higher total phenolic compound content, indicating its potential to act as an effective functional food material.
PubMed: 38790867
DOI: 10.3390/foods13101567 -
Antibiotics (Basel, Switzerland) Apr 2024TsaB/YeaZ represents a promising target for novel antibacterial agents due to its indispensable role in bacterial survival, high conservation within bacterial species,...
TsaB/YeaZ represents a promising target for novel antibacterial agents due to its indispensable role in bacterial survival, high conservation within bacterial species, and absence of eukaryotic homologs. Previous studies have elucidated the role of the essential staphylococcal protein, TsaB/YeaZ, in binding DNA to mediate the transcription of the - operon, responsible for encoding key enzymes involved in the biosynthesis of branched-chain amino acids-namely isoleucine, leucine, and valine (ILV). However, the regulation of ILV biosynthesis does not account for the essentiality of TsaB/YeaZ for bacterial growth. In this study, we investigated the impact of TsaB/YeaZ depletion on bacterial morphology and gene expression profiles using electron microscopy and deep transcriptomic analysis, respectively. Our results revealed significant alterations in bacterial size and surface smoothness upon TsaB/YeaZ depletion. Furthermore, we pinpointed specific genes and enriched biological pathways significantly affected by TsaB/YeaZ during the early and middle exponential phases and early stationary phases of growth. Crucially, our research uncovered a regulatory role for TsaB/YeaZ in bacterial autolysis. These discoveries offer fresh insights into the multifaceted biological functions of TsaB/YeaZ within .
PubMed: 38786122
DOI: 10.3390/antibiotics13050393 -
Nature Communications May 2024Glioblastoma multiforme (GBM) is a highly aggressive brain tumor characterized by invasive behavior and a compromised immune response, presenting treatment challenges....
Glioblastoma multiforme (GBM) is a highly aggressive brain tumor characterized by invasive behavior and a compromised immune response, presenting treatment challenges. Surgical debulking of GBM fails to address its highly infiltrative nature, leaving neoplastic satellites in an environment characterized by impaired immune surveillance, ultimately paving the way for tumor recurrence. Tracking and eradicating residual GBM cells by boosting antitumor immunity is critical for preventing postoperative relapse, but effective immunotherapeutic strategies remain elusive. Here, we report a cavity-injectable bacterium-hydrogel superstructure that targets GBM satellites around the cavity, triggers GBM pyroptosis, and initiates innate and adaptive immune responses, which prevent postoperative GBM relapse in male mice. The immunostimulatory Salmonella delivery vehicles (SDVs) engineered from attenuated Salmonella typhimurium (VNP20009) seek and attack GBM cells. Salmonella lysis-inducing nanocapsules (SLINs), designed to trigger autolysis, are tethered to the SDVs, eliciting antitumor immune response through the intracellular release of bacterial components. Furthermore, SDVs and SLINs administration via intracavitary injection of the ATP-responsive hydrogel can recruit phagocytes and promote antigen presentation, initiating an adaptive immune response. Therefore, our work offers a local bacteriotherapy for stimulating anti-GBM immunity, with potential applicability for patients facing malignancies at a high risk of recurrence.
Topics: Glioblastoma; Animals; Mice; Salmonella typhimurium; Male; Neoplasm Recurrence, Local; Brain Neoplasms; Humans; Cell Line, Tumor; Mice, Inbred C57BL; Pyroptosis; Adaptive Immunity; Immunity, Innate; Hydrogels; Immunotherapy
PubMed: 38762500
DOI: 10.1038/s41467-024-48606-5 -
Archives of Plastic Surgery May 2024Reconstructive surgeons face challenges when considering limb salvage methods for the treatment of diabetic foot ulcers (DFUs). In this article, we present our...
Reconstructive surgeons face challenges when considering limb salvage methods for the treatment of diabetic foot ulcers (DFUs). In this article, we present our experience with autologous fat grafting as a viable alternative in cases where flap reconstruction is difficult. We encountered a 78-year-old female patient with a nonhealing DFU who had multiple comorbidities, including renal failure and severe peripheral arterial disease. During the initial multidisciplinary meeting, due to extensive necrosis and osteomyelitis, amputation was recommended. However, the patient expressed a strong preference for a salvage procedure and refused amputation. After careful consideration, we opted to reconstruct the patient's foot using three-dimensional bioprinted autologous minimally manipulated homologous adipose tissue. The AMHAT was engrafted well without complications such as autolysis, graft failure, or infection. After the operation, the large defect with partial bone exposure was covered with healthy granulation tissue. The size of the wound decreased to less than half its original size after 6 weeks of surgery, and it decreased to less than 25% after 12 weeks of surgery. The AMHAT may be an appealing treatment option for diabetic foot patients who are unsuitable for flap reconstruction due to comorbidities.
PubMed: 38737843
DOI: 10.1055/a-2263-7957 -
Microbiology Spectrum Jun 2024infection (CDI) with high morbidity and high mortality is an urgent threat to public health, and pathogenesis studies are eagerly required for CDI therapy. The major...
infection (CDI) with high morbidity and high mortality is an urgent threat to public health, and pathogenesis studies are eagerly required for CDI therapy. The major surface layer protein, SlpA, was supposed to play a key role in pathogenesis; however, a lack of isogenic mutants has greatly hampered analysis of SlpA functions. In this study, the whole gene was successfully deleted for the first time via CRISPR-Cas9 system. Deletion of in resulted in smaller, smother-edged colonies, shorter bacterial cell size, and aggregation in suspension. For life cycle, the mutant demonstrated lower growth (changes of optical density at 600 nm, OD600) but higher cell density (colony-forming unit, CFU), decreased toxins production, and inhibited sporulation. Moreover, the mutant was more impaired in motility, more sensitive to vancomycin and Triton X-100-induced autolysis, releasing more lactate dehydrogenase. In addition, SlpA deficiency led to robust biofilm formation but weak adhesion to human host cells.IMPORTANCE infection (CDI) has been the most common hospital-acquired infection, with a high rate of antibiotic resistance and recurrence incidences, become a debilitating public health threat. It is urgently needed to study pathogenesis for developing efficient strategies as CDI therapy. SlpA was indicated to play a key role in pathogenesis. However, analysis of SlpA functions was hampered due to lack of isogenic mutants. Surprisingly, the first deletion strain was generated in this study via CRISPR-Cas9, further negating the previous thought about being essential. Results in this study will provide direct proof for roles of SlpA in pathogenesis, which will facilitate future investigations for new targets as vaccines, new therapeutic agents, and intervention strategies in combating CDI.
Topics: Clostridioides difficile; Bacterial Proteins; Humans; Gene Deletion; Clostridium Infections; Biofilms; Anti-Bacterial Agents; Virulence; CRISPR-Cas Systems; Bacterial Adhesion; Membrane Glycoproteins
PubMed: 38709045
DOI: 10.1128/spectrum.04005-23