Melting curve analysis reveals false-positive norovirus detection in a molecular syndromic panel.

BACKGROUND: Molecular syndromic panels can improve rapidity of results and ease clinical laboratory workflow, although caution has been raised for potential false-positive results. Upon implementation of a new panel for infectious diarrhea (BioFire® FilmArray® Gastrointestinal [GI] Panel, bioMérieux) in our clinical laboratory, a higher than expected number of stool samples with norovirus were detected. OBJECTIVES: The goal of this study was to investigate positive percent agreement and the false-positive rate of norovirus detected by the multiplex BioFire GI panel compared to a singleplex commercial assay. STUDY DESIGN: From October 2023 to January 2024, all prospective stool samples with a positive norovirus result by BioFire had melting curves reviewed manually using the BioFire FilmArray Torch System. Stool samples further underwent testing by a supplementary real-time RT-PCR assay (Xpert® Norovirus, Cepheid) for comparative analysis. RESULTS: Of the 50 stool samples with norovirus detected by BioFire, 18 (36 %) tested negative by Xpert (deemed "false-positives"). Furthermore, melting curve analysis revealed nearly all of these samples had atypical melting curve morphologies for the "Noro-1" target on BioFire (16/18, 89 %), which was statistically significant (Odds Ratio 173.2, 95 % CI [22.2, 5326.9], p < 0.0001). Stool samples with multiple pathogens detected by BioFire including norovirus were not more likely to produce false-positive norovirus results (Odds Ratio 1, 95 % CI [0.3, 3.3], p = 1). CONCLUSIONS: Although not described in the manufacturer's Instructions for Use, we propose routine manual review of melting curves for the BioFire GI panel prior to reporting, to mitigate potential false-positive norovirus results.

The Importance of Early Detection and Minimally Invasive Treatment of Pseudoaneurysms Due to Chronic Pancreatitis: Case Report.

The occurrence of the pseudoaneurysm of visceral arteries in the field of chronic pancreatitis is a very rare complication that represents a life-threatening condition. The higher frequency of this complication is in the necrotic form of pancreatic inflammation, especially in patients with formed peripancreatic necrotic collections. The degradation of the arterial wall leads to bleeding and transforms these necrotic collections into a pseudoaneurysm. Urgent endovascular angioembolization is the first choice in the therapeutic approach as a valid minimally invasive solution with very satisfactory immediate and long-term outcomes. This successfully avoids open surgery, which is associated with a high mortality rate in these patients, especially in acute-on-chronic pancreatitis.

Obesity and dyslipidemia in early life: Impact on cardiometabolic risk.

Childhood obesity with its growing prevalence worldwide presents one of the most important health challenges nowadays. Multiple mechanisms are involved in the development of this condition, as well as in its associations with various cardiometabolic complications, such as insulin resistance, diabetes, metabolic dysfunction-associated steatotic liver disease and cardiovascular diseases. Recent findings suggest that childhood obesity and associated dyslipidemia at least partly originate from epigenetic modifications that take place in the earliest periods of life, namely prenatal and perinatal periods. Hence, alterations of maternal metabolism could be fundamentally responsible for fetal and neonatal metabolic programming and consequently, for metabolic health of offspring in later life. In this paper, we will review recent findings on the associations among intrauterine and early postnatal exposure to undesirable modulators of metabolism, development of childhood obesity and later cardiometabolic complications. Special attention will be given to maternal dyslipidemia as a driven force for undesirable epigenetic modulations in offspring. In addition, newly proposed lipid biomarkers of increased cardiometabolic risk in obese children and adolescents will be analyzed, with respect to their predictive potential and clinical applicability.

Precision touch DNA sampling on plastic bag knots for improved profiling of packer and holder contributions.

In forensic DNA analysis, evidence sampling stands as a pivotal step setting the ground for the quality of the forensic profiling. The collection of touch DNA from objects, when guidelines are scarce or absent, is usually governed by ad hoc decisions based on the available case circumstances. In our laboratory, in the context of illicit drug-related crimes, similar objects are frequently encountered, offering an opportunity for the standardization of evidence treatment. This study aims to develop an effective method for sampling touch DNA from knots on plastic bags. We examine both the exposed and hidden areas of knots, considering the latter as "protected" zones less likely to accumulate biological material during subsequent handling. The study contrasts a single sample method (whole knot surface sampling, Method 1) with dual-sample methods that separate exterior (exposed) and interior (hidden) surfaces of the knot. Notably, our study consistently reveals higher DNA yields from exterior surfaces of the knots as opposed to interior samples. Importantly, our findings demonstrate that utilizing a single sample may produce DNA profiles that are not interpretable, while employing a dual-sample approach may allow for the differentiation between the genetic contributions of the person who tied the knot, the packer, from the person who held the package, the holder. We have refined the dual-sample method to reduce holder DNA in the interior sample while maintaining it on the exterior, also allowing the packer's DNA to be detected on both surfaces. We explore four dual-sample collection methods. Method 2 involves taking the first sample from the exterior and the second from the interior of an untied knot. Method 3 visually differentiates between the original exposed and hidden surfaces for precise sampling. Method 4 employs tools to open the knot for interior sampling. Method 5 uses Diamond dye to highlight cell-free DNA on both surfaces before sampling. In conclusion, this study not only clarifies the complex dynamics of touch DNA transfer and collection on plastic bag knots, but also offers insights into standardizing evidence collection in similar cases.

DNA degradation of bloodstains on cotton fabric caused by different washing procedures.

DNA degradation in biological material needs to be better understood. Bloodstains on washed clothing are disturbed by washing procedures, sometimes transferred to other fabrics, often with latent bloodstains and usually with significantly degraded DNA. The samples (cotton fabric with bloodstains) are divided into six main groups, depending on the washing method regarding water temperature (95, 60, and 30 °C) and the detergent use. After completing the washing process, samples were stored for a certain period (1 day to 6 months) and subsequently analyzed. Analyses were performed using standard protocols and commercial kits to measure the remaining DNA quantity (concentration) and DNA degradation index in the processed samples. Our results revealed that the high washing temperature (60 and 95 °C) and the application of detergent have a synergic action on DNA degradation, while at 30 °C this effect is absent. Furthermore, the effect of detergent on accelerated DNA degradation is observed about a month after the washing. This delayed effect of detergent has no explanation in current literature data. To obtain optimal results from the bloodstains, we recommended that the period from the crime event and attempted cleaning by a perpetrator to the laboratory analysis should be less than 1 month.

WGS of a cluster of MDR Shigella sonnei utilizing Oxford Nanopore R10.4.1 long-read sequencing.

OBJECTIVES: To utilize long-read nanopore sequencing (R10.4.1 flowcells) for WGS of a cluster of MDR Shigella sonnei, specifically characterizing genetic predictors of antimicrobial resistance (AMR). METHODS: WGS was performed on S. sonnei isolates identified from stool and blood between September 2021 and October 2022. Bacterial DNA from clinical isolates was extracted on the MagNA Pure 24 and sequenced on the GridION utilizing R10.4.1 flowcells. Phenotypic antimicrobial susceptibility testing was interpreted based on CLSI breakpoints. Sequencing data were processed with BugSeq, and AMR was assessed with BugSplit and ResFinder. RESULTS: Fifty-six isolates were sequenced, including 53 related to the cluster of cases. All cluster isolates were identified as S. sonnei by sequencing, with global genotype 3.6.1.1.2 (CipR.MSM5), MLST 152 and PopPUNK cluster 3. Core genome MLST (cgMLST, examining 2513 loci) and reference-based MLST (refMLST, examining 4091 loci) both confirmed the clonality of the isolates. Cluster isolates were resistant to ampicillin (blaTEM-1), trimethoprim/sulfamethoxazole (dfA1, dfrA17; sul1, sul2), azithromycin (ermB, mphA) and ciprofloxacin (gyrA S83L, gyrA D87G, parC S80I). No genomic predictors of resistance to carbapenems were identified. CONCLUSIONS: WGS with R10.4.1 enabled rapid sequencing and identification of an MDR S. sonnei community cluster. Genetic predictors of AMR were concordant with phenotypic antimicrobial susceptibility testing.

CT and 18FDG-PET/CT findings in progressive mediastinal idiopathic fibrosis as a benign mimicker of esophageal carcinoma: a case report.

Idiopathic mediastinal fibrosis, also called sclerosing or fibrosing mediastinitis, is a very rare and aggressive fibroinflammatory process characterized by fibrous tissue proliferation in the mediastinal region. Herein, we present a rare case of idiopathic mediastinal fibrosis presenting with esophageal obstruction, most likely associated with immunoglobulin G (IgG4)-related disease, affecting the posterior mediastinum with intrapulmonary infiltration. Computed tomography revealed a narrowed lumen and thickened wall of the distal esophagus surrounded by a necrotic mass with infiltration into the nearby structures, suggesting a locally advanced malignant process. Positron emission tomography revealed intense accumulation of 18F-fluorodeoxyglucose, indicating an active inflammatory component, which complicates further differential diagnosis of mediastinal masses. Thoracoscopic biopsy and immunohistochemical analysis confirmed a fibroinflammatory process with perivascular lymphoid cell infiltration that was cluster of differentiation (CD)3 (++) and CD20 (++), with massive numbers of IgG4-immunoreactive plasma cells. Although a benign condition, sclerosing mediastinitis is a close mimicker of esophageal carcinoma, which cannot be differentiated by computed tomography or positron emission tomography and must be considered in a differential diagnosis.

Possibility of Using Conventional Computed Tomography Features and Histogram Texture Analysis Parameters as Imaging Biomarkers for Preoperative Prediction of High-Risk Gastrointestinal Stromal Tumors of the Stomach.

BACKGROUND: The objective of this study is to determine the morphological computed tomography features of the tumor and texture analysis parameters, which may be a useful diagnostic tool for the preoperative prediction of high-risk gastrointestinal stromal tumors (HR GISTs). METHODS: This is a prospective cohort study that was carried out in the period from 2019 to 2022. The study included 79 patients who underwent CT examination, texture analysis, surgical resection of a lesion that was suspicious for GIST as well as pathohistological and immunohistochemical analysis. RESULTS: Textural analysis pointed out min norm (p = 0.032) as a histogram parameter that significantly differed between HR and LR GISTs, while min norm (p = 0.007), skewness (p = 0.035) and kurtosis (p = 0.003) showed significant differences between high-grade and low-grade tumors. Univariate regression analysis identified tumor diameter, margin appearance, growth pattern, lesion shape, structure, mucosal continuity, enlarged peri- and intra-tumoral feeding or draining vessel (EFDV) and max norm as significant predictive factors for HR GISTs. Interrupted mucosa (p < 0.001) and presence of EFDV (p < 0.001) were obtained by multivariate regression analysis as independent predictive factors of high-risk GISTs with an AUC of 0.878 (CI: 0.797-0.959), sensitivity of 94%, specificity of 77% and accuracy of 88%. CONCLUSION: This result shows that morphological CT features of GIST are of great importance in the prediction of non-invasive preoperative metastatic risk. The incorporation of texture analysis into basic imaging protocols may further improve the preoperative assessment of risk stratification.

MRI Tumor Regression Grade Combined with T2-Weighted Volumetry May Predict Histopathological Response in Locally Advanced Rectal Cancer following Neoadjuvant Chemoradiotherapy-A New Scoring System Proposal.

Modern studies focus on the discovery of innovative methods to improve the value of post-treatment magnetic resonance imaging (MRI) in the prediction of pathological responses to preoperative neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC). The aim of this study was to assess the potential benefits of combining magnetic resonance tumor regression grade (mrTRG) with T2-weighted volumetry in the prediction of pathological responses to nCRT in LARC. This was a cohort study conducted on patients with histopathologically confirmed LARC in a period from 2020 to 2022. After histopathological verification, all patients underwent initial MRI studies, while the follow-up MRI was performed after nCRT. Tumor characteristics, MRI estimated tumor regression grade (mrTRG) and tumor volumetry were evaluated both initially and at follow-up. All patients were classified into responders and non-responders according to pathological tumor regression grade (pTRG) and mrTRG. A total of 71 patients, mostly male (66.2%) were included in the study. The median tumor volume reduction rate was significantly higher in nCRT-responders compared to non-responders (79.9% vs. 63.3%) (p = 0.003). Based on ROC analysis, optimal cut-off value for tumor volume reduction rate was determined with an area under the curve (AUC) value of 0.724 (p = 0.003). Using the tumor volume reduction rate ≥75% with the addition of response to nCRT according to mrTRG, a new scoring system for prediction of pTRG to preoperative nCRT in LARC was developed. Diagnostic performance of prediction score was tested and the sensitivity, PPV, specificity, and NPV were 81.8%, 56.3%, 71.4%, and 89.7%, respectively. The combination of mrTRG and T2-weighted volumetry increases the MRI-based prediction of pTRG to preoperative nCRT in LARC. The proposed scoring system could aid in distinguishing responders to nCRT, as these patients could benefit from organ-preserving treatment and a "watch and wait" strategy.

Yersinia pseudotuberculosis bacteraemia with splenic abscesses: a case report.

Introduction: Yersinia pseudotuberculosis has been known to cause a variety of clinical manifestations ranging from mild enteric illness to bacteraemia with septic shock and extraintestinal abscesses. Patients with liver disease and iron overload are at risk of more severe disease manifestations. Case Report: A middle-aged male with chronic alcohol use disorder presented with confusion and jaundice, with ascites and asterixis noted on examination. His blood work was remarkable for neutrophilic leukocytosis, elevated liver enzymes and lactate. An abdominal computed tomography scan revealed splenic microabscesses and a cirrhotic liver. Yersinia pseudotuberculosis was recovered from his blood cultures and he was treated with ceftriaxone following susceptibility results. Conclusion: Y. pseudotuberculosis should be considered in the differential diagnosis of splenic or other extraintestinal microabscesses particularly in patients with chronic liver disease.

Morphometric and volumetric analysis of lacrimal glands in patients with thyroid eye disease.

Assessment of morphometric and volumetric changes in lacrimal glands in thyroid eye disease, its clinical manifestations in relation of disease progression. Retrospective volumetric analysis included both genders and was performed on total of 183 patients - 91 patients with diagnosed Grave's disease and thyroid eye disease and 92 patients without Grave's disease and thyroid eye disease who underwent multidetector computed tomography (MDCT) examination in routine daily work according to other medical indications. In the group of females, there was statistical significance between patients with thyroid eye disease and controls who were smoking and had body weight gain. We found statistical significance in volumetric enlargements for both orbits in both genders for the patients group when compared to controls. There was also statistical significance in morphometric characteristics for the lacrimal gland diameters measured. Determination planimetric morphometric parameters of importance were coronary height of lacrimal gland of the right eye, coronary height of lacrimal gland of the left eye and coronary width of lacrimal gland of the left eye for the group of males. In a group of females the established determination parameters of importance were the coronary height of lacrimal gland of the left eye, the axial width of lacrimal gland of the left eye, volume of lacrimal gland of the right eye and the volume of lacrimal gland of the left eye. When we compared the displaced lacrimal gland coming forward (proptosis) in time progressing disease between group of patients and controls, we also found statistical significant connection. Evaluation of lacrimal gland volumetric and morphometric data may increase validity of defining this anatomical substrate and its morphology disruption as liable tool for thyroid eye disease progression follow up and treatment planning and outcome.

Gordonia sputi-associated bloodstream infection in a renal transplant patient with chronic indwelling central venous catheter: a case report and literature review.

Introduction: Although rare, human infections caused by Gordonia spp. have been reported, especially within the immunocompromised population and those with long-term indwelling devices. We report a case of Gordonia spp. bacteraemia in a renal transplant patient and present a literature review on microbiological identification methods of this organism. Case Presentation: A 62-year-old female renal transplant recipient admitted to hospital with a 2-month history of dry cough and fevers occurring weekly when receiving electrolyte replacement infusions via a Groshong line. Over 2 weeks, blood cultures repeatedly isolated a Gram-positive bacillus solely in aerobic bottles, and this was initially reported as Rhodococcus spp. by the local microbiology laboratory. Chest computed tomography (CT) showed multiple ground-glass lung opacities suggestive of septic pulmonary emboli. As central line-associated bloodstream infection was suspected, empirical antibiotics were initiated and the Groshong line was removed. The Gram-positive bacillus was later confirmed by the reference laboratory as Gordonia sputi via 16S rRNA sequencing. Vancomycin and ciprofloxacin for a duration of 6 weeks were completed as targeted antimicrobial therapy. After treatment, the patient remained symptom-free with marked improvement on repeat CT chest imaging. Conclusion: This case illustrates the challenges surrounding identification of Gordonia spp. and other aerobic actinomycetes. 16S rRNA gene sequencing may be a preferred identification method, especially when initial workup of a weakly acid-fast organism fails to make an identification or shows discrepant results using traditional diagnostic modalities.

Cholesterol Metabolic Profiling of HDL in Women with Late-Onset Preeclampsia.

A specific feature of dyslipidemia in pregnancy is increased high-density lipoprotein (HDL) cholesterol concentration, which is probably associated with maternal endothelium protection. However, preeclampsia is most often associated with low HDL cholesterol, and the mechanisms behind this change are scarcely explored. We aimed to investigate changes in HDL metabolism in risky pregnancies and those complicated by late-onset preeclampsia. We analyze cholesterol synthesis (cholesterol precursors: desmosterol, 7-dehydrocholesterol, and lathosterol) and absorption markers (phytosterols: campesterol and ß-sitosterol) within HDL particles (NCSHDL), the activities of principal modulators of HDL cholesterol's content, and major HDL functional proteins levels in mid and late pregnancy. On the basis of the pregnancy outcome, participants were classified into the risk group (RG) (70 women) and the preeclampsia group (PG) (20 women). HDL cholesterol was lower in PG in the second trimester compared to RG (p < 0.05) and followed by lower levels of cholesterol absorption markers (p < 0.001 for campesterolHDL and p < 0.05 for ß-sitosterolHDL). Lowering of HDL cholesterol between trimesters in RG (p < 0.05) was accompanied by a decrease in HDL phytosterol content (p < 0.001), apolipoprotein A-I (apoA-I) concentration (p < 0.05), and paraoxonase 1 (PON1) (p < 0.001), lecithin-cholesterol acyltransferase (LCAT) (p < 0.05), and cholesterol ester transfer protein (CETP) activities (p < 0.05). These longitudinal changes were absent in PG. Development of late-onset preeclampsia is preceded by the appearance of lower HDL cholesterol and NCSHDL in the second trimester. We propose that reduced capacity for intestinal HDL synthesis, decreased LCAT activity, and impaired capacity for HDL-mediated cholesterol efflux could be the contributing mechanisms resulting in lower HDL cholesterol.

Clostridioides difficile PCR Tcdb Cycle Threshold predicts toxin EIA positivity but not severity of infection.

BACKGROUND: Diagnosis of Clostridioides difficile Infection (CDI) entails compatible clinical presentation and laboratory findings. We evaluated real-time polymerase chain reaction (qPCR) cycle threshold (CT) as a predictor for disease severity and TcdB enzyme immunoassay (EIA) results. METHODS: Inpatients or emergency department patients who tested positive for tcdB gene by PCR were evaluated. Patients' stools underwent testing for GDH and TcdA/B by EIA. Medical health records were reviewed for demographic, clinical presentation, laboratory, treatment and outcome data. Severity of CDI was calculated using various severity score indexes. RESULTS: The median CT of cases was 32.05 ± 5.45. The optimal cut-off for predicting toxin EIA positivity and severe CDI based on chart review was 32.6 and 29.8, respectively, with the area under the receiver operator characteristics curve (AUC) of 0.74 and 0.60 respectively. CONCLUSION: CT value was an acceptable predictor for EIA toxin but less so for clinical severity. Our study potentially supports a diagnostic algorithm including CT value to reduce the number of EIA toxin assays performed.

Obesity and Dyslipidemia: A Review of Current Evidence.

PURPOSE OF REVIEW: Obesity is accompanied by atherogenic dyslipidemia, a specific lipid disorder characterized by both quantitative and qualitative changes of plasma lipoproteins. The main alterations in the lipid profile include hypertriglyceridemia, reduced high-density lipoprotein (HDL) cholesterol level, and elevated small dense low-density lipoprotein (LDL) particles. Epidemiological data show that obesity is more common in women and is a frequent risk factor for reproductive disorders, metabolic complications in pregnancy, and cardiometabolic disease later in life. The aim of this narrative review is to discuss recent advances in the research of dyslipidemia in obesity, with an emphasis on female-specific disorders and cardiometabolic risk. RECENT FINDINGS: The focus of current research on dyslipidemia in obesity is moving toward structurally and functionally modified plasma lipoproteins. Special attention is paid to the pro-atherogenic role of triglyceride-rich lipoproteins and their remnants. Introduction of advanced analytical techniques enabled identification of novel lipid biomarkers with potential clinical applications. In particular, proteomic and lipidomic studies have provided significant progress in the comprehensive research of HDL's alterations in obesity. Obesity-related dyslipidemia is a widespread metabolic disturbance in polycystic ovary syndrome patients and high-risk pregnancies, but is seldom evaluated with respect to its impact on future cardiometabolic health. Obesity and associated cardiometabolic diseases require a more depth insight into the quality of lipoprotein particles. Further application of omics-based techniques would enable a more comprehensive evaluation of dyslipidemia in order to reduce an excessive cardiovascular risk attributable to increased body weight. However, more studies on obesity-related female reproductive disorders are needed for this approach to be adopted in daily clinical practice.

No Isolate, No Problem: Using a Novel Insertion Sequence PCR to Link Rats to Human Shigellosis Cases in an Underserved Urban Community.

During an investigation into a cluster of Shigella flexneri serotype 2a cases in an underserved community, we assessed the relatedness of human and rat S. flexneri isolates utilizing a novel PCR targeting insertion sites (IS-PCR) of mobile elements in the Shigella genome characteristic of the cluster strain. Whole-genome sequences of S. flexneri (n = 50) associated with the cluster were analyzed. De novo genome assemblies were analyzed by a Geneious V10.2.6 motif search, and two unique IS were identified in all human Shigella sequences of the local cluster. Hydrolysis probe PCR assays were designed to detect these sequences consisting of forward and reverse primers to amplify across each insertion site and a hydrolysis probe spanning the insertion site. IS-PCR was performed for three Shigella PCR-positive culture-negative rat intestine specimens from this community. Both insertion sites were detected in the de novo genome assemblies of all clinical S. flexneri isolates (n = 50). Two of the three PCR-positive culture-negative rat samples were positive for both unique ISs identified in the human S. flexneri isolates, suggesting that the rat Shigella species strains were closely related to the human strains in the cluster. The cycle threshold (Ct) values were >35, indicating that the bacterial load was very low in the rat samples. Two unique IS were identified in clinical isolates from a community S. flexneri cluster. Both IS targets were identified in PCR-positive (Shigella spp.), culture-negative rat tissue and clinical isolates from humans, indicating relatedness. IMPORTANCE This article describes a novel molecular method to show relatedness between bacterial infections, which may not be able to grow in the laboratory due to treatment with antibiotics or for bacteria requiring unique conditions to grow well. Uniquely, we applied this technique to Shigella isolates from human cases associated with a local cluster in an underserved community, as well as rat samples from the same community. We believe that this novel approach can serve as a complementary method to support outbreak/cluster investigation for Shigella spp.

The Prospect of Genomic, Transcriptomic, Epigenetic and Metabolomic Biomarkers for The Personalized Prevention of Type 2 Diabetes and Cardiovascular Diseases.

Cardiometabolic diseases, such as type 2 diabetes mellitus (DM) and cardiovascular disease (CVD), are a great health concern. The strategies aimed to increase awareness and prevention, in conjunction with timely diagnosis and optimal management of these conditions, represent the main lines of action to improve life expectancy and quality. In recent years, the introduction of innovative therapies for the treatment of DM and CVD has provided new hope for high-risk patients. Yet, the implementation of preventive measures in achieving cardiometabolic health is far from successful and requires further improvement. The development of cardiometabolic disorders is a complex, multifactorial process involving several metabolic pathways as well as genetic and environmental factors. Decreasing cumulative exposure during the entire life course and timely recognition and targeting of potential riskenhancing factors could pave the way toward more successful prevention of cardiometabolic disorders. Nowadays, in the era of "omics" technologies, it is possible to identify novel biomarkers and therapeutic targets, which offers the possibility to apply an individualized approach for each patient. This review will discuss potential applications of genomic, transcriptomic, epigenetic and metabolomic biomarkers for the personalized prevention of cardiometabolic diseases.

Alterations of cholesterol synthesis and absorption in obstructive sleep apnea: Influence of obesity and disease severity.

BACKGROUND AND AIMS: Obstructive sleep apnea (OSA) is closely linked to obesity and related adverse metabolic changes, including dyslipidemia. However, it is not clear whether OSA is an independent contributing factor to dyslipidemia, or the observed association is a reflection of a concomitant presence of obesity. Additionally, dyslipidemia is usually evaluated through measurement of parameters of routine lipid status, while more precise evaluation of lipid homeostasis is rarely performed in OSA. In this study, we analyzed markers of cholesterol synthesis and absorption in patients with OSA with respect to the presence of obesity and the disease severity. METHODS AND RESULTS: This study enrolled 116 OSA patients. Concentrations of non-cholesterol sterols (NCS), measured by LC-MS/MS, were used as markers of cholesterol synthesis and absorption. Apnea-hypopnea index (AHI) and oxygen saturation (SaO2) were utilized as markers of OSA severity. Serum lipid status parameters were determined by routine enzymatic methods. Markers of cholesterol synthesis were increased (P = 0.005), whilst markers of cholesterol absorption decreased (P = 0.001) in obese OSA patients. Cholesterol synthesis/absorption ratio was elevated in obese subjects (P < 0.001). Concentration of cholesterol synthesis marker lathosterol was significantly higher in subjects with severe OSA (P = 0.014) and we observed a trend of decreased cholesterol absorption in these patients. AHI was revealed as an independent determinant of lathosterol concentration (P = 0.022). CONCLUSIONS: Our results suggest that the presence of obesity and severe forms of OSA is characterized by elevated endogenous cholesterol synthesis. AHI was singled out as an independent determinant of the serum level of cholesterol synthesis marker lathosterol.