Laboratory medicine最新文献

Background: One possible way to improve accuracy of blood culture Gram stain analyses is increasing the concentration of organisms on the slide prepared from the blood culture broth.

Methods: From each positive blood culture bottle, 1 direct smear, a 1-drop concentrated preparation, and 1 cytospin/cytofuge preparation were Gram stained and evaluated. There were 2 evaluators who ranked the 3 preparations from most to fewest organisms seen. Each preparation was also scored as acceptable or unacceptable for both organism and background stain quality.

Results: The 1-drop slide exhibited the highest concentration of organisms compared with both the cytospin and direct smear but presented frequent difficulties with interpretation of Gram staining acceptability with both the background and the organisms. Although cytospin preparations are known to concentrate liquid specimens, the current study found no enrichment of microorganisms over the direct smear preparation. The cytospin was, however, advantageous for enhancing organism morphology by creating a monolayer of elements and reducing background artifacts.

Conclusion: The 1-drop preparation is simple, inexpensive, and effective at increasing organism concentration for analysis, making it a good option when processing culture bottles with low organism loads, but more investigation into methods of improving stain quality is necessary.

Specimen hemolysis is a frequent finding when blood is collected from neonates. This produces artificially high results for some analytes, such as potassium. Testing samples for electrolytes using point-of-care (POC) blood gas analyzers is convenient and facile. However, unlike testing that is conducted on serum or plasma from a central laboratory, detection of hemolysis using POC analyzers cannot currently be achieved. As described in these cases, the presence of hemolysis can produce ambiguities and delays in the diagnosis and management of neonates.

Background: The use of xylene substitutes is becoming more common in the setting of micrographic surgery frozen tissue section staining, and dermatologic surgeons need to be aware of possible undesirable delayed effects of using these agents and the possibility of modifying H&E staining protocols to prevent delayed fading. This report demonstrates an undesirable outcome of using an isoparaffinic aliphatic hydrocarbon as a xylene substitute, implementation of a quality improvement intervention to eliminate frozen section slide fading in the setting of micrographic surgery tissue processing, and recommendations for the modification of protocol when using a xylene substitute.

Clinical and laboratory information: Frozen section slides processed with xylene and xylene substitute were analyzed by histotechnicians, a dermatopathologist, and a micrographic surgery surgeon at 1-week and 1-month intervals. The use of a standard H&E protocol resulted in zero stains fading when using xylene as a clearing agent, but delayed fading when using a xylene substitute.

Discussion: Using an isoparaffinic aliphatic hydrocarbon as a xylene substitute can lead to excess water carryover, which may result in delayed hematoxylin fading in micrographic surgery tissue staining, so using this xylene substitute likely requires modification to the dehydration phase and tap water immersion phase to prevent fading.

AB antigen is formed by glycosyltransferase enzyme, which catalyzes the corresponding substrates to be connected to the galactose of the precursor substance H antigen. To study the effect of the α-1,3-D galactosyltransferase (GTB) gene mutation on B antigen expression, we explored its molecular mechanism by combining molecular biological methods with bioinformatics. The ABO blood type of the patients was identified using conventional serologic methods, and the polymerase chain reaction (PCR) products of exons 1-7 of the ABO gene were directly sequenced using gene-specific primers and direct sequencing. Proteins in the secretory supernatant of transfected cells were collected in vitro, and GTB content was quantitatively analyzed using western blotting. Bioinformatics software was used to simulate the 3-dimensional structure of the mutant protein. In this case, the patient's serologic test results revealed subtype B. Gene sequencing results confirmed a mutation at base 278 of exon 6. The mutation (c.278C>T) changed the 93rd amino acid of the protein polypeptide chain from proline to leucine (p.P93L). The variant p.P93L did not affect the expression and secretion of GTB, but affected enzyme activity and stability, ultimately manifesting as weakened expression of the B antigen and reduced affinity.

Objective: Identification of instrument failure (IF) represents a point to improve the quality of services provided by medical laboratories. Here, a logistic regression model was created to define the relationship between instrument downtime and laboratory quality management systems.

Methods: Interval-level quality control (QC) and categorical quality assurance data from 3 identical chemistry analyzers was utilized to generate a logistic regression model able to predict IF. A case-control approach and the forward stepwise likelihood-ratio method was used to develop the logistic regression model. The model was tested using a case-control dataset and again using the complete sample.

Results: A total of 650 downtime events were identified. A total of 22,880 QC data points, 187 calibrations, 24 proficiency testing events, and 107 maintenance records were analyzed. The regression model was able to correctly predict 59.2% of no instrument downtime events and 69.2% of instrument downtime events using the case-control data. Using the entire data set, the sensitivity of the model was 69.2% and the specificity was 58.2%.

Conclusion: A logistic regression model can predict instrument downtime nearly 70% of the time. This study acts as a proof of concept using a limited data set collected by the chemistry laboratory.

Objective: Lymphocyte phenotyping is a valuable tool for monitoring the effects of antiretroviral therapy on individuals living with HIV-1. A switch study was conducted to compare T-cell subset quantification performed by a research laboratory and a diagnostic, laboratory to understand the impact on the retrospective and prospective results of a long-term study.

Methods: Using FACSCanto II Flow Cytometers, EDTA anticoagulated peripheral blood from 73 males enrolled in the Multicenter AIDS Cohort Study/Women Interagency HIV Combined Cohort Study was analyzed by both a research (laboratory 1) and a diagnostics laboratory (laboratory 2) for quantification of cluster of differentiation (CD)3, CD4, and CD8 T-cells. There were 47 males living with and 26 living without HIV-1.

Results: Bland-Altman (B-A) analysis was applied to assess the agreement between laboratory 1 and laboratory 2 results. There were 69 out of 73 CD3, 71 out of 73CD4, and 72 out of 73 CD8 T-cell results that fell within acceptable B-A limits of agreement. The mean differences between the 2 laboratories were -1.000, -0.945, and +0.685(%), respectively.

Conclusion: The strong agreement between results from laboratory 1 and laboratory 2 for CD3, CD4, and CD8 T-cell percentage suggests that the difference between laboratories using the same instrumentation and methodology will have a minimal effect on long-term study results.

Objective: The aim of this study was to investigate the relationship between tumor microenvironment markers (myeloid-derived suppressor cells [MDSCs], regulatory T cells [Tregs], programmed cell death 1 [PD-1], and programmed death ligand 1 [PD-L1]) and chemotherapy efficacy and prognosis in advanced gastric cancer, identifying potential monitoring indicators.

Methods: Advanced gastric cancer patients' MDSC and Treg expression was measured by flow cytometry pre- and postchemotherapy; PD-1 and PD-L1 expression in cancer tissues was assessed by immunohistochemistry. Correlations with chemotherapy outcomes and prognosis were analyzed.

Results: Postchemotherapy reductions in MDSC and Treg levels correlated with chemotherapy efficacy (P <.01). Negative PD-1 and PD-L1 expression in cancer tissues predicted better chemotherapy responses (P <.01). Patients with lower MDSC and Treg levels and negative PD-1 and PD-L1 had significantly longer median progression-free survival (PFS) and overall survival (OS) (P <.05).

Conclusion: In advanced gastric cancer, reduced peripheral blood MDSC and Treg levels postchemotherapy and negative PD-1 and PD-L1 expression in tissues are associated with improved chemotherapy efficacy and are independent prognostic factors for PFS and OS.

Introduction: System-wide laboratory internal audits are useful to help laboratories prepare for external audits in addition to being part of the ongoing program for compliance improvement and quality assurance in the laboratory to track and enhance care quality.

Methods: A formal plan was developed and a modified audit checklist was prepared by our laboratory management team, applicable and uniquely tailored for our ambulatory care clinic settings to track operational, quality, and compliance metrics according to the New York State Department of Health Clinical Laboratory Evaluation Program. Two audits were conducted 6 months apart and the conformity documented.

Results: An overall 84% increase in compliance and conformity was observed between first and second audits, which ranged from 63% to 100% across different categories, with 100% improvement (0% nonconformity) in 75% of the sites in the second audit.

Conclusion: A system-wide laboratory internal audit was created and carried out. Staff shortages, rapid turnover, and lack of retraining were found to be contributing factors to sites that did not achieve 100% conformance. Continuous assessment and monitoring are key elements to success in the laboratory quality management system, and through this scheduled audit process, we were able to achieve continual laboratory quality improvement.

Background and aims: Preanalytical errors due to interferences can lead to inaccurate results, necessitating an understanding of potential interferences for each test. This study explores the impact of elevated concentrations of ascorbic acid and glucose on urine analysis, a pivotal diagnostic tool.

Methods: Conducted at the Clinical Institute of Chemistry, KBC Sestre milosrdnice, the research utilized a 24-hour urine sample. Parameters assessed included total proteins, albumin, amylase, sodium, potassium, chlorides, calcium, phosphates, magnesium, creatinine, urea, and uric acid. Various concentrations of added interferents were prepared for duplicate measurements using statistical analysis in Microsoft Excel.

Results: No statistically significant interferences were found in albumin, amylase, sodium, potassium, or phosphate concentrations. However, ascorbic acid interfered with chloride, calcium, and magnesium determinations. Conversely, elevated glucose affected total protein, calcium, magnesium, creatinine, urea, and uric acid determinations. Interference of ascorbic acid with chloride and interference of glucose with total proteins and uric acid displayed a linear relationship.

Conclusions: Results suggest cautious analysis interpretation from certain parameters in patients with elevated glucose and/or ascorbic acid in urine. Whereas ascorbic acid interference may go unnoticed due to its infrequent measurement, routine determination of glucose in urine is crucial, especially for diabetes patients.

Background: Meningiomas are the most common intracranial tumors and their diagnosis relies mostly on neuroimaging and histology. However, the histology grades cannot predict the outcome exactly and some meningiomas tend to recur after resection of even benign tumors. Therefore, it is necessary to explore prognostic and diagnostic molecular targets.

Methods: Differential expression analysis between meningiomas and meninges was performed based on the merged data of GSE43290 and GSE84263. Next, we performed gene set enrichment analysis (GSEA), immune cell infiltration analysis, protein-protein interaction analysis, and survival analysis using public data. The expression level of Synaptosome-associated-protein-25kDa (SNAP25) was verified by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) and Western blotting in meningioma tissues.

Results: There were 263 upregulated and 592 downregulated genes identified in meningiomas by differential expression analysis. GSEA results revealed that meningiomas were negatively related to the pathway of soluble N-ethylmaleimide sensitive factor attachment protein receptor interactions in vascular transport and chemokine signaling. SNAP25 was characterized as a hub gene and downregulated in meningiomas. The Kaplan-Meier plot indicated that high expression of SNAP25 is a favorable factor.

Conclusion: SNAP25 was downregulated and identified as a potential prognostic marker in meningioma.