Harika Oyku Dinc

Background: The association between Helicobacter pylori and the resident gastric microbiota plays a critical role in gastric carcinogenesis; however, the specific microbial alterations accompanying the transition from chronic inflammation to malignancy remain to be fully elucidated. This study aimed to characterize the distinct bacterial signatures associated with gastric cancer (GC) and non-ulcer dyspepsia (NUD) within a Turkish cohort, evaluating these structural shifts in the context of the “hit-and-run” hypothesis. Methods: Genomic DNA was isolated from 158 gastric biopsy specimens obtained from 96 individuals stratified into four homogeneous groups based on clinical H. pylori status and histopathological presentation: H. pylori-positive GC (Hp+GC, n = 37), H. pylori-negative GC (Hp-GC, n = 25), H. pylori-positive NUD (Hp+NUD, n = 17), and H. pylori-negative NUD (Hp-NUD, n = 17). Next-generation amplicon sequencing targeting the V3–V4 hypervariable regions of the 16S rRNA gene was executed, followed by strict quality filtering via the DADA2 pipeline and taxonomic classification against the SILVA database. Results: Alpha diversity analysis demonstrated a significant reduction in microbial richness and evenness within the Hp+GC group compared with all other cohorts (FDR-adjusted q < 0.001). Beta diversity metrics revealed distinct ecological trajectories, with the overall microbial community structure of the Hp+GC group diverging sharply from non-malignant controls. Taxonomic profiling unveiled a profound dysbiotic shift in the Hp+GC microenvironment, characterized by a massive depletion of the Firmicutes phylum and a concomitant overrepresentation of Proteobacteria (66.56%). While the Helicobacter genus predominated in the non-malignant Hp+NUD group, its relative abundance declined to negligible levels (Enterobacteriaceae family, showing highly significant enrichment of Morganella (11.14% mean relative abundance; FDR-adjusted q < 0.001), Providencia (3.43%; FDR-adjusted q < 0.001), and Klebsiella (2.03%; FDR-adjusted q < 0.001). Conclusions: These findings support the “hit-and-run” model, indicating that H. pylori acts as an initiator of carcinogenesis but is progressively outcompeted by an aggressive, nitrate-reducing, and pro-inflammatory Enterobacteriaceae-dominated dysbiotic bacterial community as mucosal atrophy and hypochlorhydria neutralize the typical acidic gastric barrier.

This study aimed to assess the humoral immune response following administration of a BNT162b2 mRNA COVID‐19 booster dose and to evaluate its association with the development of SARS‐CoV‐2 infection after vaccination. Between July 2021 and February 2022, serum samples were collected from 313 individuals 28 days after receiving a COVID‐19 booster dose. Quantitative SARS‐CoV‐2 IgG antibodies directed against the receptor‐binding domain (RBD) of the spike protein were measured using a chemiluminescent microparticle immunoassay. Neutralizing antibody activity, defined as inhibition of the RBD–ACE2 interaction, was evaluated semi‐quantitatively by a competitive ELISA. Participants were followed for 6 months after the final dose to identify confirmed SARS‐CoV‐2 infections. The cohort included 97 males (31%) and 216 females (69%), with a mean age of 39.43 years. The median SARS‐CoV‐2 IgG antibody level at day 28 was 7713.3 AU/mL, and the median neutralizing antibody inhibition rate was 99.2%. Antibody levels were not significantly associated with age or comorbidities. Booster vaccination induced a strong humoral immune response in all participants. However, the occurrence of post‐vaccination infections despite high antibody levels suggests immune escape by emerging variants. While vaccines may not fully prevent infection, they provide substantial protection against severe disease and mortality.

Introduction: This systematic review aimed to provide a comprehensive evaluation of the immunopathological mechanisms associated with SARS-CoV-2 infection and COVID-19 vaccination based on current evidence. Particular emphasis was placed on cytokine storm, endothelial dysfunction, complement activation, and autoimmune processes in COVID-19 pathogenesis. Methods: The study was conducted as a systematic literature review in accordance with PRISMA guidelines. English-language research articles published between 2020 and 2026 were identified through a structured search of the Scopus database. A total of 1,331 records were screened, and 53 studies were included based on predefined inclusion and exclusion criteria. The findings were systematically categorized according to major immunopathological mechanisms. Results: The included studies indicate that endothelial dysfunction (24.5%) and cytokine dysregulation (18.9%) are the most frequently reported mechanisms in COVID-19 immunopathogenesis. Autoimmune responses (15.1%), complement activation (17%), and immune complex–mediated inflammation also play significant roles. Elevated levels of proinflammatory cytokines, lymphopenia, and markers of vascular injury were consistently associated with increased disease severity and mortality. In addition, persistent immunological alterations and autoantibody production were observed in a subset of patients during the post-COVID period. Conclusion: COVID-19 pathogenesis is driven by complex and interconnected immunopathological mechanisms rather than viral effects alone. Hyperinflammation, endothelial dysfunction, complement activation, and autoimmune processes are key determinants of disease severity and clinical outcomes. These findings underscore the importance of targeted immunomodulatory strategies and provide a comprehensive framework for future research.

This study aimed to comparatively evaluate the conventional hepatitis B surface antigen (HBsAg) assay and the next-generation HBsAg NEXT (HBsAgNx) assay in samples with low-level HBsAg positivity and in cases of occult hepatitis B infection (OBI). A total of 497 individuals were included in the study, comprising 300 individuals with low-level HBsAg positivity, 100 OBI cases (64 seropositive and 36 seronegative) and 97 healthy controls. Serum samples were analyzed using the Abbott ARCHITECT HBsAg Qualitative II assay (Abbott Diagnostics, Wiesbaden, Germany) and the Abbott Alinity i HBsAg NEXT assay (Abbott Diagnostics, Wiesbaden, Germany). The presence of HBV DNA was confirmed by real-time polymerase chain reaction (Rt-PCR) using the COBAS AmpliPrep/COBAS TaqMan HBV test v2.0 (Roche Diagnostics, Mannheim, Germany). HBV DNA (Rt-PCR) was accepted as the gold standard reference for diagnostic performance evaluation. To minimize potential bias arising from sample selection, individuals with lowlevel HBsAg positivity and OBI cases were analyzed separately. In the low-level HBsAg-positive group, semi-quantitative S/CO values of the assays were compared, whereas in the OBI group, only the detection rates of HBV DNA-positive cases were evaluated. A total of 17 OBI cases (17%) were identified that were tested negative by the conventional assay but positive by the HBsAgNx assay. Differences between the assays were evaluated using the McNemar test and p< 0.05 was considered statistically significant. Median values obtained with the HBsAgNx assay were significantly higher than those obtained with the conventional assay (p< 0.001). The HBsAgNx assay provides clinically significant contributions particularly in the OBI group, by detecting cases that cannot be identified by conventional assays. These findings indicate that the integration of high-sensitivity HBsAg assays into current HBV diagnostic algorithms would increase case detection and contribute to both transfusion safety and the clinical management of OBI.

This study focused on synthesizing and characterizing novel thiosemicarbazide derivatives containing a 1,2,4-triazole moiety and evaluating their antimicrobial activity against several bacterial strains. The research aimed to identify key structural features that enhance antimicrobial efficacy through structure-activity relationship analysis and identify the minimum inhibitory concentration (MIC) of the most potent compounds to assess their potential for further development as antimicrobial agents. Nine novel thiosemicarbazide derivatives containing a 1,2,4-triazole moiety were synthesized by reacting 1,2,4-triazole derivatives with thiosemicarbazide precursors, and the products were characterized using infrared spectroscopy, proton nuclear magnetic resonance (¹H-NMR), carbon-13 nuclear magnetic resonance (¹³C-NMR) spectroscopy, and elemental analysis. The antimicrobial activity of these compounds (5a-i) was tested against Klebsiella pneumoniae (K. pneumoniae),Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, and Pseudomonas aeruginosa (P. aeruginosa), using microdilution, disk diffusion, and broth microdilution methods. Dimethyl sulfoxide was used as a negative control, and Vancomycin and Meropenem were used as positive controls, with all results converted to µM for consistent analysis. The synthesized thiosemicarbazide derivatives (5a-i) were confirmed to be structurally correct through Fourier-transform infrared spectroscopy, ¹H-NMR, and ¹³C-NMR spectroscopy. Among the tested compounds, 5e (4-bromophenyl) and 5g (n-propyl) showed significant antimicrobial activity, with 5g exhibiting the strongest effects against S. aureus and P. aeruginosa. Other derivatives, such as 5b (4-NO₂Ph), 5c (4-FPh), and 5d (4-ClPh), showed moderate activity, while no significant activity was observed against K. pneumoniae or E. faecalis. The study successfully synthesized a series of novel thiosemicarbazide derivatives with a 1,2,4-triazole moiety and evaluated their antimicrobial potential. Compounds 5e and 5g exhibited significant antibacterial activity, particularly against S. aureus and P. aeruginosa, with MIC values in the low micromolar range. These findings suggest that the compounds hold promise as potential antimicrobial agents, and further studies should focus on optimizing their efficacy and exploring their mechanism of action.

Cite this article as: Ergün İ, Dinç HÖ, Burtecene N, et al. Evaluating the humoral immune response to sinovac-coronavac in a pediatric patient with propionic acidemia: A case study. Turk Arch Pediatr. 2025;60(4):440-442.

The increase in antimicrobial resistance poses a significant challenge in medicine, necessitating the exploration of novel antimicrobial agents. Temporin A and Apidaecin B, two naturally occurring antimicrobial peptides (AMPs), have garnered attention for their potent bactericidal properties. This study aimed to investigate the antimicrobial activities of Temporin A and Apidaecin B against clinical strains isolated from blood cultures and evaluate their potential as alternative therapeutic agents. A total of 12 Escherichia coli, 13 Klebsiella pneumoniae, 13 Staphylococcus aureus, and 12 Staphylococcus epidermidis strains were used for antimicrobial susceptibility tests. Antimicrobial activities were evaluated using the broth microdilution method. MIC values were detected as <3.9 for Temporin A against S. aureus and S. epidermidis and 7.81 for Apidaecin B against E. coli. The results underscore the potent antimicrobial properties of Temporin A against S. aureus and S. epidermidis, and Apidaecin B against E. coli. Further research is needed to optimize AMPs’ stability, delivery mechanisms, and efficacy in vivo.

In this comprehensive screening study, the chemical composition, and cytotoxic, antimicrobial, and anticholinergic activities of the green algae Penicillus capitatus, collected from Antalya‐Türkiye, were determined as in vitro and in silico. GC‐MS analysis of the hexane extract revealed a high content of fatty acids, with hexadecanoic acid constituting half of the total fatty acid content. LC‐HRMS analysis of the DCM:MeOH extract identified ascorbic acid as the most abundant compound, followed by (−)‐epigallocatechin and salicylic acid. The DCM:MeOH extract exhibited potent cytotoxicity against MDA‐MB‐231 and MCF7 breast cancer cell lines, outperforming doxorubicin with lower IC₅₀ values and a higher selectivity index. Additionally, the extract demonstrated significant antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans, along with selective inhibition of acetylcholinesterase (hAChE) over butyrylcholinesterase (hBChE). Molecular docking and dynamics studies revealed that apigenin‐7‐O‐glucoside and epigallocatechin form stable interactions with estrogen receptor alpha (ERα) and hAChE, suggesting their potential as inhibitors. In silico ADME studies indicated favorable pharmacokinetic profiles for the detected compounds, supporting their potential as drug candidates. The promising cytotoxic activity of the P. capitatus extracts, coupled with significant antimicrobial properties and selective hAChE inhibition, highlights their therapeutic potential for breast cancer treatment, infection management, and neurodegenerative disease intervention.

Background: As hemodialysis patients are among the vulnerable groups for severe COVID-19, proper vaccination of these patients is quite important. However vaccine responsiveness is generally reduced in hemodialysis patients and strategies should be developed to maintain protection in the long term. Objectives: This study aimed to analyse the changes in antibody levels of SARS-CoV-2 vaccinated hemodialysis patients after six months and to compare the effectiveness of inactivated and mRNA vaccines. Methods: Eighty-five hemodialysis patients were followed up for six months after their initial vaccinations for SARS-CoV-2. Persistence of humoral responses were compared between patients who got inactivated or mRNA vaccines and also between patients who received a booster dose and those who didn’t. SARS-CoV-2 antibody titers were measured by a commercial test that measures IgG antibodies toward the receptor-binding domain of spike protein. Results: Seropositivity that was achieved by initial vaccination dropped abruptly by 6 months. Patients who received a booster dose had significantly higher antibody levels than those who didn’t (1120,8 ± 983,3 AU/mL vs 313,3 ± 435,3 AU/mL respectively; p<0,001) and higher seropositivity as well (88% vs 65%). Seropositivity with mRNA vaccine at the end of 6th month was 81,8% while this decreased to 50% for inactivated vaccine. Patients who received mRNA vaccine initially or as the third dose could maintain 88,4% of seropositivtiy and this was higher than other patients who have just got inactivated vaccine (p=0,013). Conclusion: Humoral immune response by SARS-CoV-2 vaccines is not very stable in hemodialysis patients and planning the booster doses should not be delayed. mRNA vaccines have better immunogenicity than inactivated vaccines.