Strongyloides infection screening in transplant candidates: What is the best strategy?

BACKGROUND

The potential that Strongyloides stercoralis infection has to cause major morbidity and high mortality when the disseminated form occurs in transplant patients is of particular concern.

METHODS

In this study, the objective was to observe S. stercoralis infection in patients who are candidates for transplantation by using parasitological, serological, and molecular techniques and to propose an algorithm for the detection of that infection in transplant candidates.

RESULTS

By parasitological techniques, 10% of fecal samples were positive. Anti-Strongyloides antibodies immunoglobulin G were detected in 19.3% and 20.7% of patients by immunofluorescence assay and enzyme-linked immunosorbent assay, respectively. S. stercoralis DNA was observed in 17.3% of samples by conventional polymerase chain reaction and 32.7% of samples by quantitative polymerase chain reaction (qPCR).

CONCLUSION

The set of results allows us to reinforce that a positive result by parasitological techniques and/or qPCR indicates that the specific treatment should be applied. However, the improvement of diagnostic techniques may suggest changes in the screening for strongyloidiasis in these patients.

Toxocara canis 30-35 kDa excretory-secretory antigen is an important marker in mice challenged by inocula containing different parasite load levels

The Western-blotting technique was applied to identify antigenic fractions of excretory-secretory Toxocara canis antigen recognized by IgG antibodies throughout an experimental infection in mice challenged by different inocula. Mice were inoculated with 5, 50 and 500 embryonated eggs and serum samples were collected 15, 30, 60, 90 and 120 days post-infection. Serum samples were analyzed using an excretory-secretory Toxocara antigen. Antibodies recognized antigenic fractions from 30 to 90 kDa. The protein fraction of 30-35 kDa was the most frequently recognized regardless of the size of inoculum and the stage of infection represented by the different collection times, but the antigenic recognition was more evident in groups infected with 50 and 500 eggs. This study presents an antigenic panel of the excretory-secretory antigen of T. canis and suggests that the 30-35 kDa antigenic fraction is a promising marker of the infection and should be further explored in future studies on experimental toxocariasis.

Diagnosis of human strongyloidiasis: Application in clinical practice

This review considers the advantages and disadvantages of parasitological techniques, methods of detecting antibodies and antigens, as well as molecular biology techniques in the diagnosis of human strongyloidiasis. In addition, it elucidates the potential of different techniques for rapid and effective detection of clinical cases, thus enabling early treatment and preventing fatal consequences of this helminthiasis.

A Novel Saliva RT-LAMP Workflow for Rapid Identification of COVID-19 Cases and Restraining Viral Spread

Rapid diagnostics is pivotal to curb SARS-CoV-2 transmission, and saliva has emerged as a practical alternative to naso/oropharyngeal (NOP) specimens. We aimed to develop a direct RT-LAMP (reverse transcription loop-mediated isothermal amplification) workflow for viral detection in saliva, and to provide more information regarding its potential in curbing COVID-19 transmission. Clinical and contrived specimens were used to optimize formulations and sample processing protocols. Salivary viral load was determined in symptomatic patients to evaluate the clinical performance of the test and to characterize saliva based on age, gender and time from onset of symptoms. Our workflow achieved an overall sensitivity of 77.2% (n = 90), with 93.2% sensitivity, 97% specificity, and 0.895 Kappa for specimens containing >102 copies/μL (n = 77). Further analyses in saliva showed that viral load peaks in the first days of symptoms and decreases afterwards, and that viral load is ~10 times lower in females compared to males, and declines following symptom onset. NOP RT-PCR data did not yield relevant associations. This work suggests that saliva reflects the transmission dynamics better than NOP specimens, and reveals gender differences that may reflect higher transmission by males. This saliva RT-LAMP workflow can be applied to track viral spread and, to maximize detection, testing should be performed immediately after symptoms are presented, especially in females.

IgG reactivity with 40-35 kDa soluble and membrane antigen of Strongyloides venezuelensis in immunocompromised patients

Immunocompromised patients constitute a risk group for the development of severe clinical forms of human strongyloidiasis. The diagnosis of this infection is primarily performed by parasitological techniques, but with low sensitivity. Serological techniques appear as an alternative, especially with heterologous antigens use. The aim of this study was to perform the Western blot technique by using S. venezuelensis infective third stage larva (iL3) soluble (TS) and membrane (TM) saline antigens to reveal immunoreactive bands in immunocompromised patients with strongyloidiasis. Serum samples from 117 parasitologically well-characterized patients were divided into four groups: S. stercoralis positive and immunocompetent (S + IC); S. stercoralis positive and immunocompromised (S + IP); negative and immunocompetent (S-IC); negative and immunocompromised (S-IP). A 40-35 kDa band was recognized by 100% of patients in the S + IC group in both antigenic fractions, and by 62.5% and 50% in the S + IP group using the TS and TM fractions, respectively. A 29 kDa band was recognized by 86.3% and 72.7% (for TS and TM, respectively) of patients in the S + IC group, and only by 12.5% of patients in the S + IP group on the TM antigen. Regardless of the patients' immunological condition, the 40-35 kDa band from S. venezuelensis was detected more frequently and can be used as an important marker to the immunodiagnosis of human strongyloidiasis.

Could mucin 16 and colony-stimulating factor 2-receptor beta possible graft versus host disease biomarkers? Medical hypotheses

Graft versus host disease (GVHD) occurs after bone marrow transplantation and is one of the most important causes of death worldwide. Reviews demonstrated GVHD patients with involvement of various tissues and organs, such as salivary glands. The diagnosis of acute GVHD has been the biopsies and the histopathologic evaluation of tissue from an involved organ. These procedures are invasive. Saliva proteins as possible biomarker for GVHD could facilitate the management and diagnosis accuracy. For support the proposed hypotheses, in this pilot study we collected whole saliva samples from patients with undergoing allogeneic hematopoietic cell transplantation (HCT) and from healthy subjects. Samples were collected prospectively between pre-transplant, thirty days, one hundred and, two hundred days after transplant. The proteomic profile was analyzed using SDS-PAGE and LCMS-ESI-IT-TOF mass spectrometry. The relevant personal data, past medical history were also recorded. The most relevant proteins found exclusively in GVHD patients were: CSF2RB, Protocadherin (Pcdh) Fat 2 precursor, protein capicua homolog isoform CIC-S, MUC16 and RGPD8_HUMAN RANBP2. This study aims to conduct an initial evaluation of the possible presence of such biomarkers in saliva from GVHD patients, and suggested a potential application of proteomics analysis as a alternative method to diagnose GVHD.

DIAGNOSIS OF Strongyloides stercoralis INFECTION IN IMMUNOCOMPROMISED PATIENTS BY SEROLOGICAL AND MOLECULAR METHODS

Strongyloidiasis is a potentially serious infection in immunocompromised patients. Thus, the availability of sensitive and specific diagnostic methods is desirable, especially in the context of immunosuppressed patients in whom the diagnosis and treatment of strongyloidiasis is of utmost importance. In this study, serological and molecular tools were used to diagnose Strongyloides stercoralis infections in immunosuppressed patients. Serum and stool samples were obtained from 52 patients. Stool samples were first analyzed by Lutz, Rugai, and Agar plate culture methods, and then by a quantitative real time polymerase chain reaction (qPCR). Serum samples were evaluated by an enzyme-linked immunosorbent assay (ELISA) using a soluble (AS) or a membrane fractions antigen (AM) obtained from alkaline solutions of the filariform larvae of Strongyloides venezuelensis. Of the 52 immunosuppressed patients, three (5.8%) were positive for S. stercoralis by parasitological methods, compared to two patients (3.8%) and one patient (1.9%) who were detected by ELISA using the AS and the AM antigens, respectively. S. stercoralis DNA was amplified in seven (13.5%) stool samples by qPCR. These results suggest the utility of qPCR as an alternative diagnostic tool for the diagnosis of S. stercoralis infection in immunocompromised patients, considering the possible severity of this helminthiasis in this group of patients.

IMMUNODIAGNOSIS OF HUMAN STRONGYLOIDIASIS: USE OF SIX DIFFERENT ANTIGENIC FRACTIONS FROM Strongyloides venezuelensis PARASITIC FEMALES

The aim of this study was to evaluate six different antigenic fractions from Strongyloides venezuelensis parasitic females for the immunodiagnosis of human strongyloidiasis. Soluble and membrane fractions from S. venezuelensis parasitic females were prepared in phosphate-buffered saline (SSF and SMF, respectively), Tris-HCl (TSF and TMF, respectively), and an alkaline buffer (ASF and AMF, respectively). Serum samples obtained from patients with strongyloidiasis or, other parasitic diseases, and healthy individuals were analyzed by enzyme-linked immunosorbent assay (ELISA). Soluble fractions SSF, TSF, and ASF showed 85.0%, 75.0%, and 80.0% sensitivity and 93.1%, 93.1%, and 87.5% specificity, respectively. Membrane fractions SMF, TMF, and AMF showed 80.0%, 75.0%, and 85.0% sensitivity, and 95.8%, 90.3%, and 91.7% specificity, respectively. In conclusion, the present results suggest that the fractions obtained from parasitic females, especially the SSF and SMF, could be used as alternative antigen sources in the serodiagnosis of human strongyloidiasis.

Membrane fractions from Strongyloides venezuelensis in the immunodiagnosis of human strongyloidiasis

Strongyloides venezuelensis is a parasitic nematode of rodents frequently used to obtain heterologous antigens for the immunological diagnosis of human strongyloidiasis. The aim of this study was to evaluate membrane fractions from S. venezuelensis for human strongyloidiasis immunodiagnosis. Soluble and membrane fractions were obtained in phosphate saline (SS and SM) and Tris-HCl (TS and TM) from filariform larvae of S. venezuelensis. Ninety-two serum samples (n = 92) were obtained from 20 strongyloidiasis patients (Group I), 32 from patients with other parasitic diseases (Group II), and 40 from healthy individuals (Group III), and were analyzed by enzyme-linked immunosorbent assay (ELISA). Soluble fractions (SS and TS) showed 90.0% sensitivity and 88.9% specificity, whereas the membrane fractions (SM and TM) showed 95.0% sensitivity and 94.4% specificity. The present results suggest the possible use of membrane fractions of S. venezuelensis as an alternative antigen for human strongyloidiasis immunodiagnosis.

Parasitological and molecular diagnosis in experimental Strongyloides venezuelensis infection

Strongyloides venezuelensis is a parasitic nematode of rats which is frequently used as a model to study human and animal strongyloidiasis. The aim of this study was to evaluate the correlation between parasitological and molecular diagnosis in Strongyloides venezuelensis infection. PCR assays were used to detect S. venezuelensis DNA in fecal samples obtained from experimentally infected Rattus norvegicus. The results showed a higher sensitivity of the PCR assay in detecting the infection compared to parasitological methods.

[Radiological diagnostic approach to idiopathic interstitial pneumonias: findings in high resolution computed tomography]

A review is presented on the histological and radiological findings in idiopathic interstitial pneumonias, which are included among the diffuse parenchymal lung diseases. Although they may affect other compartments, the lung interstitium is the initial substrate of the parenchymal lesion due to different patterns of inflammation and fibrosis. The current classification, proposed in 2002 as an international multidisciplinary consensus document promoted by the American Thoracic Society and the European Respiratory Society, includes 7 conditions. Based on histological criteria, each histological pattern is associated with an image pattern. They are a group of conditions of unknown origin with common characteristics and differential features that enable them to be individualised as diseases with a different prognosis and treatment. They are rare as idiopathic forms, but share a morphological substrate with other more common diseases of unknown cause, which means they have to be excluded to reach a definitive diagnosis. For this reason it is important that the radiologist is familiar with their characteristic imaging findings.

1-Oxaspiro[4.4]nonan-6-ones. Synthetic access via oxonium ion technology, optical resolution, and conversion into enantiopure spirocyclic alpha,beta-butenolides

A general approach to the synthesis of enantiomerically pure spirocyclic alpha,beta-butenolides is presented where the fundamental framework is rapidly elaborated by acid- or bromonium ion-induced rearrangement of the carbinol derived by addition of 2-lithio-4,5-dihydrofuran to cyclobutanone. Subsequent resolution of the resulting ketones by either sulfoximine or mandelate acetal technology has been applied effectively. The availability of these building blocks makes possible in turn the acquisition of the enantiomers of dihydrofurans typified by 17, 35, and 38 and lactones such as 25 and 31, as well as the targeted title compounds. Complementary reductions of the early intermediates provide the added advantage that the alpha- and beta-stereoisomeric carbinol series can be obtained on demand. These capabilities have been coordinated to allow the crafting of any member of the series in relatively few steps.

A clinopathologic review of 8 liver graft primary nonfunctions

In a group of 276 consecutive liver transplants 8 primary graft nonfunctions were identified (2.9%). Recipients showed a progressive elevation of transferases (mean maximum value ALT: 5000 +/- 1892 U/l) and bilirubin (mean maximum value: 20 +/- 11.8 mg/dl) and a decrease in the percent prothrombin time (mean minimum value 26 +/- 13 min.) in the post-implantation survival time of the 8 grafts (range 1-5 days). No statistically significant differences were observed between mean cold and warm-ischemia times for these 8 donor organs and those of a control group of 92 consecutive grafts. All organs except one were ABO isogroup and all except another one displayed negative lymphocytotoxic crossmatch. Predominantly small-droplet hepatocytic vacuolization with no nuclear displacement was observed in plastic-embedded semithin sections of all post-primary nonfunction liver tissues (severe in 4 grafts, centri-mediozonal in 2, and centrolobular in 2). In 3 cases where fresh liver tissue was available the lipidic nature of the vacuoles was confirmed with electron microscopy and with frozen sections stained with Sudan III. Other microscopic lesions were also observed: spotty monocellular coagulative necroses, variable extension of zonal coagulative necroses and hemorrhages, cholestasis and minor mixed inflammatory infiltrate. Comparative microscopic study of these tissues with the protocol biopsy specimens obtained 2-4 hours after reperfusion demonstrated previous liver cell-vacuolization in only 3 cases. In conclusion, an acute progressive microvascular steatosis developed in this primary nonfunction series. No specific etiopathogenic factors were identified.