An Overview of Laboratory Testing for ADAMTS13.

ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) is also called von Willebrand factor (VWF) cleaving protease (VWFCP). ADAMTS13 acts to cleave VWF multimers and thus reduce plasma VWF activity. In the absence of ADAMTS13 (i.e., in thrombotic thrombocytopenia purpura, TTP), plasma VWF can accumulate, in particular as "ultra-large" VWF multimers, and this can lead to thrombosis. Relative deficiencies in ADAMTS13 can also occur in a variety of other conditions, including secondary thrombotic microangiopathies (TMA). Of contemporary interest, COVID-19 (coronavirus disease 2019) may also be associated with relative reduction of ADAMTS13 and also pathological accumulation of VWF, with this likely contributing to the thrombosis risk seen in affected patients. Laboratory testing for ADAMTS13 can assist in the diagnosis of these disorders (i.e., TTP, TMA), as well as in their management, and can be achieved using a variety of assays. This chapter therefore provides an overview of laboratory testing for ADAMTS13 and the value of such testing to assist the diagnosis and management of associated disorders.

Expert consensus on laboratory testing for sars-COV-2.

With the global outbreak of the coronavirus disease 2019, the laboratory testing for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) has become the key to the epidemic prevention and control. Based on the questions, issues from the clinical practice and the latest research, the Sub-committee of Clinical Microbiology Laboratory, Chinese Hospital Association proposed "Expert Consensus on Laboratory Testing for SARS-CoV-2". The consensus panel is composed by experts in clinical microbiology, molecular biology and immunology laboratory medicine. The consensus describes the technological characteristics, precautions of clinical application, and biosafety requirements. It also includes the coping strategies for the most frequent problems and the challenges in testing and results explanation of commonly used clinical methods including nucleic acid, antibody and antigen tests, and combined testing of nucleic acid and antibody. We expect this consensus could provide guidances and reference opinions on how to conduct the precise laboratory testing for SARS-CoV-2 on the epidemic prevention and control.Copyright © 2021, Peking Union Medical College Hospital. All rights reserved.

A prognostic model for classification of COVID-19 severity based on clinical and laboratory testing data

This study aimed to build an machine learning based model to predict the COVID-19 severity and reveal risk factors related to COVID-19 severity based on laboratory testing and clinical data for 420 participants, using tree-based models such as XGBoost, LightGBM, random forest. We calculated the Odds Ratios (OR) to investigate whether the top-ranked features were statistically significant for severity classification, turning out that high sensitivity C-reactive protein (hs-CRP) was the most important feature for determining of COVID-19 severity and XGBoost model showed the highest performance in classifying COVID-19 severity and healthy controls with F1score (0.84) and AUC (0.87). We expect that our results are of considerable significance for early screening for diagnosing COVID-19 severity, which, in turn, assist in further retrospective research for uncommon infectious diseases. © 2023 IEEE.

Age, comorbidities, c-reactive protein and procalcitonin as predictors of severity in confirmed COVID-19 patients in the Philippines.

Background: The Coronavirus Disease 2019 (COVID-19) pandemic has been affecting people globally, and the Philippines is one of the countries greatly struck by the virus. The continued rise of new positive cases has drawn attention to the urgent need for healthcare management to cope with this challenge. Severity prediction could help improve medical decision-making and optimise the patient's treatment plan with a good clinical outcome. This study aimed to identify the determinants of COVID-19 disease severity. Methods: Demographic characteristics and laboratory findings were collected from electronic medical records and paper forms of all confirmed COVID-19 cases reported by the University of Perpetual Help DALTA Medical Center between the September 1, 2020 and the October 31, 2021. We performed statistical analyses and interpretation of data to compare severe and non-severe groups. Results: 5,396 confirmed cases were examined. Most of the severe cases were elderly, male, had blood type A, and with comorbidities. Cycle threshold (Ct) values were lower in the severe group. Most patients had higher-than-normal levels of all blood parameters except platelet, white blood cell (WBC), neutrophil, and lymphocyte counts. Age, sex, ABO blood groups, comorbidities, open reading frame 1 ab (ORF1ab) and nucleocapsid (N) gene Ct values, ferritin, C-reactive protein (CRP), procalcitonin (PCT), D-dimer, white blood cell (WBC) count, neutrophil count, and lymphocyte count were significantly associated with disease severity. In multivariate analysis, age groups >60 and 30-59 years, presence of comorbidities, CRP level >5 ng/mL, and PCT >0.05 ng/mL were identified as disease severity predictors. Conclusions: Based on our results, age, comorbidities, CRP, and PCT level may be utilised as primary assessment factors for possible hospital admission and close monitoring upon testing. Early detection of these risk factors may provide strategic interventions that help reduce mortality, hospital admissions, and more expensive and extensive treatments.

Fungal Pathogens as Causes of Acute Respiratory Illness in Hospitalized Veterans: Frequency of Fungal Positive Test Results Using Rapid Immunodiagnostic Assays.

Fungal respiratory illnesses caused by endemic mycoses can be nonspecific and are often mistaken for viral or bacterial infections. We performed fungal testing on serum specimens from patients hospitalized with acute respiratory illness (ARI) to assess the possible role of endemic fungi as etiologic agents. Patients hospitalized with ARI at a Veterans Affairs hospital in Houston, Texas, during November 2016-August 2017 were enrolled. Epidemiologic and clinical data, nasopharyngeal and oropharyngeal samples for viral testing (PCR), and serum specimens were collected at admission. We retrospectively tested remnant sera from a subset of patients with negative initial viral testing using immunoassays for the detection of Coccidioides and Histoplasma antibodies (Ab) and Cryptococcus, Aspergillus, and Histoplasma antigens (Ag). Of 224 patient serum specimens tested, 49 (22%) had positive results for fungal pathogens, including 30 (13%) by Coccidioides immunodiagnostic assays, 19 (8%) by Histoplasma immunodiagnostic assays, 2 (1%) by Aspergillus Ag, and none by Cryptococcus Ag testing. A high proportion of veterans hospitalized with ARI had positive serological results for fungal pathogens, primarily endemic mycoses, which cause fungal pneumonia. The high proportion of Coccidioides positivity is unexpected as this fungus is not thought to be common in southeastern Texas or metropolitan Houston, though is known to be endemic in southwestern Texas. Although serological testing suffers from low specificity, these results suggest that these fungi may be more common causes of ARI in southeast Texas than commonly appreciated and more increased clinical evaluation may be warranted.

Monkeypox virus diagnosis and laboratory testing.

The multi-country outbreak of monkeypox virus (MPXV) infection, while the coronavirus disease 2019 pandemic is still an ongoing issue, has caused a new challenge. The re-emergence of MPXV and the rising incidence in non-endemic countries is turning into an upcoming threat to global health. Hence, rapid identification of the virus with appropriate methodology with the lowest false results plays a critical role in estimating the global extent of the crisis and providing preventive measures. This review summarised the main applicable strategies for primary detection and confirmation of MPXV and highlighted available data in biosafety, requirements, standard operating procedures, specimen collection, transportation and storage of clinical samples, and waste disposal of the viral agent. Also, various assays including molecular techniques, immunoassays, histopathological methods, electron microscopy, genomic sequencing, and cell culture have been illustrated. Moreover, we reflected on current knowledge of the advantages and disadvantages of each approach.

Autoimmune complications of COVID-19 and potential consequences for long-lasting disease syndromes.

The latest WHO report determined the increasing diversity within the CoV-2 omicron and its descendent lineages. Some heavily mutated offshoots of BA.5 and BA.2, such as BA.4.6, BF.7, BQ.1.1, and BA.2.75, are responsible for about 20% of infections and are spreading rapidly in multiple countries. It is a sign that Omicron subvariants are now developing a capacity to be more immune escaping and may contribute to a new wave of COVID-19. Covid-19 infections often induce many alterations in human physiological defense and the natural control systems, with exacerbated activation of the inflammatory and homeostatic response, as for any infectious diseases. Severe activation of the early phase of hemostatic components, often occurs, leading to thrombotic complications and often contributing to a lethal outcome selectively in certain populations. Development of autoimmune complications increases the disease burden and lowers its prognosis. While the true mechanism still remains unclear, it is believed to mainly be related to the host autoimmune responses as demonstrated, only in some patients suffering from the presence of autoantibodies that worsens the disease evolution. In fact in some studies the development of autoantibodies to angiotensin converting enzyme 2 (ACE2) was identified, and in other studies autoantibodies, thought to be targeting interferon or binding to annexin A1, or autoantibodies to phospholipids were seen. Moreover, the occurrence of autoimmune heparin induced thrombocytopenia has also been described in infected patients treated with heparin for controlling thrombogenicity. This commentary focuses on the presence of various autoantibodies reported so far in Covid-19 diseases, exploring their association with the disease course and the durability of some related symptoms. Attempts are also made to further analyze the potential mechanism of actions and link the presence of antibodies with pathological complications.

Severe Acute Respiratory Syndrome Coronavirus 2 Serology Testing - A Laboratory Primer.

In 2019, an emerging coronavirus, SARS-COV-2, was first identified. In the months since, SARS-CoV-2 has become a global pandemic of unimaginable scale. In 2021, SARS-CoV-2 continues to be a huge public health burden and a dominating issue in health care. In addition, SARS-CoV-2 has placed a spotlight on laboratory medicine and its key role in infectious disease management. The SARS-CoV-2 antibody testing landscape is vast and consists of dozens of antibody tests that have received EUA. The laboratory is faced with choosing the right test, staying current with the rapidly evolving recommendations, and updating test information for clients and clinicians. This review addresses what we know about the humoral response in SARS-CoV-2 infection and how this knowledge translates into appropriate serology test choice, utility, and interpretation.

Monkeypox virus diagnosis and laboratory testing.

The multi-country outbreak of monkeypox virus (MPXV) infection, while the coronavirus disease 2019 pandemic is still an ongoing issue, has caused a new challenge. The re-emergence of MPXV and the rising incidence in non-endemic countries is turning into an upcoming threat to global health. Hence, rapid identification of the virus with appropriate methodology with the lowest false results plays a critical role in estimating the global extent of the crisis and providing preventive measures. This review summarised the main applicable strategies for primary detection and confirmation of MPXV and highlighted available data in biosafety, requirements, standard operating procedures, specimen collection, transportation and storage of clinical samples, and waste disposal of the viral agent. Also, various assays including molecular techniques, immunoassays, histopathological methods, electron microscopy, genomic sequencing, and cell culture have been illustrated. Moreover, we reflected on current knowledge of the advantages and disadvantages of each approach.

Laboratory and Point-of-Care Testing for COVID-19: A Review of Recent Developments.

With the emergence of Coronavirus infection called COVID-19, testing is essential for containment and mitigation purposes. In a pandemic, control is essential to limit the spread of any virus. Initially, contact tracing was not available which ultimately led to the 2020 pandemic. However, with the development of COVID-19 rapid testing, the rate of infections has lessened and has allowed for some return to normalcy. In this review, we discuss the various antibody, antigens, and molecular tests that have been given emergency authorization (EA) from the Food and Drug Administration (FDA). Moreover, we will discuss the various point-of-care tests as well as the specificity and sensitivity that are associated with each testing kit. With appropriate testing, we can be aware of how the virus spreads and how prevalent it remains.

Effect of Nucleic Acid Screening Measures on COVID-19 Transmission in Cities of Different Scales and Assessment of Related Testing Resource Demands-Evidence from China.

BACKGROUND: COVID-19 is in its epidemic period, and China is still facing the dual risks of import and domestic rebound. To better control the COVID-19 pandemic under the existing conditions, the focus of this study is to simulate the nucleic acid testing for different population size cities in China to influence the spread of COVID-19, assess the situation under different scenarios, the demand for the laboratory testing personnel, material resources, for the implementation of the nucleic acid screening measures, emergency supplies, and the configuration of human resources to provide decision-making basis. METHODS: According to the transmission characteristics of COVID-19 and the current prevention and control strategies in China, four epidemic scenarios were assumed. Based on the constructed SVEAIiQHR model, the number of people infected with COVID-19 in cities with populations of 10 million, 5 million, and 500,000 was analyzed and predicted under the four scenarios, and the demand for laboratory testing resources was evaluated, respectively. RESULTS: For large, medium, and small cities, whether full or regional nucleic acid screening can significantly reduce the epidemic prevention and control strategy of different scenarios laboratory testing resource demand difference is bigger, implement effective non-pharmaceutical interventions and regional nucleic acid screening measures to significantly reduce laboratory testing related resources demand, but will cause varying degrees of inspection staff shortages. CONCLUSION: There is still an urgent need for laboratory testing manpower in China to implement effective nucleic acid screening measures in the event of an outbreak. Cities or regions with different population sizes and levels of medical resources should flexibly implement prevention and control measures according to specific conditions after the outbreak, assess laboratory testing and human resource need as soon as possible, and prepare and allocate materials and personnel.

Review on Automatic Covid-19 Detection from Chest CT Images using Artificial Intelligence

The corona virus is one of the widespread diseases affected globally. The corona virus was first found in Wuhan, China in December 2019. The disease caused by the corona virus is named Covid-19. Covid-19 can be diagnosed by laboratory testing and chest radiography method. Due to limitations of laboratory testing methods like RT-PCR (Reverse Transcript polymerase Chain Reaction) for Covid-19 detection, medical image-based techniques have been proposed by various researchers. In this paper, various papers were reviewed that used machine learning and deep learning methods from Chest X-rays and chest CT for Covid-19 diagnosis. The overall performance of these methods is measured in terms of accuracy, sensitivity, specificity, and F1 score. © 2022 IEEE.

Respiratory Syncytial Virus During the COVID-19 Pandemic Compared to Historic Levels: A Retrospective Cohort Study of a Health System.

BACKGROUND: Surveillance in 2020-2021 showed that seasonal respiratory illnesses were below levels seen during prior seasons, with the exception of interseasonal respiratory syncytial virus (RSV). METHODS: Electronic health record data of infants aged <1 year visiting the Duke University Health System from 4 October 2015 to 28 March 2020 (pre-COVID-19) and 29 March 2020 to 30 October 2021 (COVID-19) were assessed. International Classification of Diseases-Tenth Revision (ICD-10) codes for RSV (B97.4, J12.1, J20.5, J21.0) and bronchiolitis (RSV codes plus J21.8, J21.9) were used to detail encounters in the inpatient (IP), emergency department (ED), outpatient (OP), urgent care (UC), and telemedicine (TM) settings. RESULTS: Pre-COVID-19, 88% of RSV and 92% of bronchiolitis encounters were seen in ambulatory settings. During COVID-19, 94% and 93%, respectively, occurred in ambulatory settings. Pre-COVID-19, the highest RSV proportion was observed in December-January (up to 38% in ED), while the peaks during COVID-19 were seen in July-September (up to 41% in ED) across all settings. RSV laboratory testing among RSV encounters was low during pre-COVID-19 (IP, 51%; ED, 51%; OP, 41%; UC, 84%) and COVID-19 outside of UC (IP, 33%; ED, 47%; OP, 47%; UC, 87%). Full-term, otherwise healthy infants comprised most RSV encounters (pre-COVID-19, up to 57% in OP; COVID-19, up to 82% in TM). CONCLUSIONS: With the interruption of historical RSV epidemiologic trends and the emergence of interseasonal disease during COVID-19, continued monitoring of RSV is warranted across all settings as the changing RSV epidemiology could affect the distribution of health care resources and public health policy.

Preventive Health Screening during the COVID-19 Pandemic: A Cross-Sectional Survey among 102,928 Internet Users in Poland.

Preventive screening is a highly cost-effective public health intervention. The COVID-19 pandemic may impact preventive healthcare services. This study aimed to assess the frequency of preventive health screening, as well as to identify the factors associated with compliance with health screening guidelines among adults in Poland during the COVID-19 pandemic. This cross-sectional survey was carried out between October and December 2021, among Internet users in Poland. Respondents were asked about the last date that they performed seven different screening tests. Completed questionnaires were obtained from 102,928 adults aged 18-99 years, and 57.2% were female. The most common screening tests performed in the past 12 months were blood pressure measurement (83%), blood count (66.2%), and blood sugar (63.3%). Moreover, more than half of respondents had a urinalysis (53.1%) and lipid panel (55.1%) in the past 12 months. Out of 58,904 females, 69.2% had a cervical cytology in the past 3 years. Older age, having higher education, living in urban areas, being occupationally active, having at least one chronic disease, and visiting a doctor in the past 12 months were significantly associated (p < 0.001) with a higher level of compliance with screening guidelines. This study revealed a significant gap in the performance of preventive health screening.

Biosafety risk assessment and risk control of clinical laboratory in designated hospitals for treating COVID-19 in Chongqing, China.

BACKGROUND: If a nucleic acid preservation solution containing viral inactivators is used, the biosafety risk in the process of detecting the nucleic acid of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will be low. Patients infected with SARS-CoV-2 are sent to designated hospitals for treatment in China, except for detecting nucleic acid of SARS-CoV-2, other laboratory tests such as bacterial culture may also be carried out while the patients are being treated. However, in addition to nucleic acid testing, biosafety risks in the testing of these items for patients with coronavirus disease 2019 (COVID-19) might be ignored. Therefore, we identified and evaluated risks in these detection processes and formulated appropriate, but not excessive control measures for biosafety risk, to improve the work efficiency and prevent biosafety accidents. METHODS: Biosafety risks in all laboratory tests for COVID-19 patients were identified and evaluated according to the risk severity and occurrence probability. Subsequently, the corresponding control measures for biosafety risk were formulated according to the identified risk. Hereafter, risk monitoring was carried out. RESULTS: More than 32 risks in the entire laboratory testing process were identified and evaluated, and the residual risk after the implementation of the control measures was acceptable. CONCLUSIONS: The biosafety risk assessment of laboratories in designated hospitals for treating COVID-19 should be re-implemented before testing specimens for COVID-19 patients. Risk management by risk monitoring is even more important, as it can prevent the occurrence of biosafety incidents and can continuously improve risk management.

Clinical characteristics and laboratory testing of patient with Sar CoV2 infection

Background: Sar CoV2, a novel coronavirus was identified as the cause of respiratory abnormality diseases COVID-19. It has no specific symptoms and the transmission occurs via respiratory droplets or contaminated surfaces. Seroprevalence studies of many diseases have been found to be useful to detect people who were exposed to infection and reveal the burden of the disease. Objectives: This study aimed to assess the correlation between Clinical findings and laboratory testing of patients with Sar CoV2 infection as derived by RT PCR detection and to investigate serological antibody of IgM, IgG in serum of Covid19 hospitalized patients. Materials and methods: The study was conducted on 168 patients with positive RT PCR for COVID-19 during June 2021-January 2022 in Khon Kaen Hospital. The nasopharyngeal swabs and blood samples were obtained on the day of admission. Data collection of patient’s clinical symptoms and laboratory testing were recorded for statistical analysis. We performed CBC and anti Sar CoV2 (IgM,IgG) according to standard laboratory methods. Results: The results indicated that seroprevalence of anti Sar CoV2 in COVID-19 patients was approximately 28% (47/168). The laboratory markers of CBC;as WBC, neutrophil, lymphocyte and platelet demonstrated lower significance. No correlation was observed between Ct of RT PCR with clinical signs and symptoms of COVID-19 patients. In case of RBC, Hemoglobin and Hematocrit, there were also no correlation with clinical characteristics of COVID-19 patients. Conclusion: The study observed that WBC count and platelet count was significantly lower for some cases. However, awareness of these parameters is required, because of the large heterogeneity in test performance. From serological tests it was observed that anti Sar CoV2 is not suitable diagnosis of the acute phase of infection. Both tests can be used to help RT PCR for diagnosis of Sar CoV2 infection. © 2022, Faculty of Associated Medical Sciences, Chiang Mai University. All rights reserved.

Covid-19 associated reduction in hypertension-related diagnostic and therapeutic procedures in Excellence Centers of the European Society of Hypertension.

BACKGROUND: The Covid-19 pandemic necessitated a decrease in non-Covid-19 related diagnostic and therapeutic procedures in many countries. We explored the impact on tertiary hypertension care. METHODS: We conducted an electronic survey regarding 6 key procedures in hypertension care within the Excellence Center network of the European Society of Hypertension. RESULTS: Overall, 54 Excellence Centers from 18 European and 3 non-European countries participated. From 2019 to 2020, there were significant decreases in the median number per centre of ambulatory blood pressure monitorings (ABPM: 544/289 for 2019/2020), duplex ultrasound of renal arteries (Duplex RA: 88.5/55), computed tomographic/magnetic resonance imaging angiography of renal arteries (CT/MRI RA: 66/19.5), percutaneous angioplasties of renal arteries (PTA RA: 5/1), laboratory tests for catecholamines (116/67.5) and for renin/aldosterone (146/83.5) (p < 0.001 for all comparisons, respectively). While reductions in all assessed diagnostic and therapeutic procedures were observed in all annual 3-months periods in the comparisons between 2019 and 2020, the most pronounced reduction occurred between April and June 2020, which was the period of the first wave and the first lockdown in most affected countries. In this period, the median reductions in 2020, as compared to 2019, were 50.7% (ABPM), 47.1% (Duplex RA), 50% (CT/MRI RA), 57.1% (PTA RA), 46.9% (catecholamines) and 41.0% (renin/aldosterone), respectively. Overall differences in reduction between 3-month time intervals were statistically highly significant. CONCLUSION: Diagnostic and therapeutic procedures related to hypertension were dramatically reduced during the first year of the Covid-19 pandemic, with the largest reduction during the first lockdown. The long-term consequences regarding blood pressure control and, ultimately, cardiovascular events remain to be investigated.

Evaluation and Validation of the Roche Elecsys SARS-CoV-2 Antigen Electro-Chemiluminescent Immunoassay in a Southeast Asian Region.

INTRODUCTION: SARS-CoV-2 antigen tests can complement and substitute for RT-PCR tests. Centralized laboratory automated SARS-CoV-2 antigen tests that can be scaled to process a large number COVID-19 cases simultaneously are now available. We have evaluated the new Roche Elecsys SARS-CoV-2 antigen electro-chemiluminescent immunoassay. METHODS: The Roche SARS-CoV-2 antigen assay is a double-antibody sandwich electro-chemiluminescent immunoassay, which reports a cut-off index (COI) (COI ≥ 1.0 considered positive). We assessed assay precision and linearity, and confirmed the reactivity limit. We determined the assay sensitivity and specificity with a verification group (289 controls and 61 RT-PCR positive COVID-19 cases). Assay performance was also validated against the consecutive samples we received (7657 controls and 17 cases) for SARS-CoV-2 antigen testing from June to October 2021. RESULT: The assay had a within-run precision CV of 3.0% at COI 0.68, and a CV of 1.5% at COI 3.49. Between-run precision was 3.0% at COI 0.68 and 1.8% at COI 3.49. The assay was linear from COI 0.65 to 7.84. All 35 C50 ± 20% test results performed over 7 days were positive/negative, respectively. In the verification group, overall sensitivity was 42.6% (26/61 positive, 95% CI 30.0-55.9), and specificity was 99.7% (1/289 positive, 95% CI 98.1-100). The agreement between the SARS-CoV-2 antigen and the RT-PCR cycle threshold (Ct) count was good (r = 0.90). In cases with Ct counts ≤ 30, the antigen assay sensitivity improved to 94.7% (18/19 positive, 95% CI 74.0-99.9). In our validation group, antigen sensitivity was 62.5% (5/8 antigen positive, 95% CI 24.5-91.5) within the first week of disease onset, but no cases were reactive after the first week of disease onset. CONCLUSION: The Elecsys SARS-CoV-2 antigen assay has good performance within manufacturer specifications. The sensitivity of the Roche antigen assay was greatest when used in patients with lower RT-PCR Ct values (≤30) and within the first week of disease onset.

Optimizing Deep Convolutional Neural Network with Fine-Tuning and Data Augmentation for Covid-19 Prediction

Since Corona virus disease 2019 (Covid-19) has been infecting people worldwide, it is important to detect Covid-19 at an earlier phase to fight against the pandemic. Pathogenic and laboratory testing are needed to determine whether someone is infected or not by Covid-19. However, this laboratory test is relatively time consuming and could produce significant false negative rates. This paper presents a study on Covid-19 detection by using deep learning algorithms aiming to predict and detect Covid-19. A set of chest X-ray images are used as the input datasets to prepare and to train the proposed model. In this study, a deep learning architecture (DLA) and optimisation strategies have been proposed and investigated to maintain the automated Covid-19 detection. A platform and a model model based on convolutional neural network (CNN) is introduced to extract the feature of X-ray images for feature learning phase in order to make the model suitable for the problem. Two strategies are applied to improve the performance of proposed model, i.e. Data augmentation and fine-tuning with deep-feature-based. A classifier are employed in order to enhance the performance of model. The experimental investigation was performed between the proposed work with the pre-trained DLAs, such as VGG16 and ResNet50. The results of this study affirm that the proposed model and VGG16 obtain better classification accuracy of 98% and 95% of sensitivity respectively. © 2021 IEEE.

Laboratory testing for platelet factor 4 antibodies: differential utility for diagnosis/exclusion of heparin induced thrombocytopenia versus suspected vaccine induced thrombotic thrombocytopenia.

Platelet factor 4 (PF4), a protein stored in the alpha-granules of platelets and released upon activation, forms cationic tetramers that bind with various polymeric anions, including heparin. Some individuals develop antibodies against PF4 in complex with heparin (PF4/H), which potentially lead to the onset of heparin induced thrombocytopenia (HIT). In some patients, this may cause activation and aggregation of platelets, promoting pathological thrombosis, in a process called heparin induced thrombocytopenia with thrombosis ('HITT'). Laboratories can assess for the presence of these antibodies using many PF4 antibody tests, including by enzyme linked immunosorbent assay (ELISA), latex immunoassay (LIA), chemiluminescence immunoassay (CLIA) and even rapid nanoparticle based lateral flow immunoassays. All these assays can identify such antibodies with high sensitivity, but methods may have variable specificity. For example, several studies have shown CLIA assays to have higher specificity to HITT than ELISA assays. Very recently, a new 'HITT-like' syndrome has been described in some individuals receiving adenovirus based COVID-19 (coronavirus disease 2019) vaccines. This condition has been given several names, including vaccine induced thrombotic thrombocytopenia (VITT) and thrombosis with thrombocytopenia syndrome (TTS), and also involves a mechanism mediated by antibodies formed against PF4. These antibodies can also be detected by PF4 antibody tests, but detection sensitivity appears to favour ELISA assays, with most other tests (including CLIA and LIA) not generally capable of detecting such antibodies. Additional functional assays assessing for PF4 mediated platelet activation may also be performed. The current review is focussed on laboratory testing for PF4 antibodies, in particular to distinguishing patterns in HITT versus VITT.