High-Dose Hook Effect in 17-Hydroxyprogesterone Assay in a Patient with 21-Hydroxylase Deficiency

Quantification of pharmacokinetic profiles of a recombinant canine PD-1 fusion protein by validated sandwich ELISA method

Tumors are becoming a serious threat to the quality of life of human and dogs. Studies have shown that tumors have caused more than half of the deaths in older dogs. Similar to human, dogs will develop various and highly heterogeneous tumors, but there are currently no viable therapies for them. In human, immunotherapy has been used widely and considered as an effective treatment for tumors by immune checkpoint targets, which are also expressed on canine tumors, suggesting that immunotherapy may be a potential treatment for canine tumors. In this work, we developed a sandwich ELISA method to detect the concentration of recombinant canine PD-1 fusion protein in canine serum and investigated pharmacokinetics in canines after intravenous infusion administration. After being validated, the ELISA method showed an excellent linear relationship in 25.00–3,200.00 ng/ml in serum, and the R² was more than 0.99 with four-parameter fitting. The precision and accuracy of intra-assay and inter-assay at the five different concentrations met the requirements of quantitative analysis. At the same time, no hook effect was observed at the concentration above ULOQ, and the stability was good under different predicted conditions with accuracy > 80%. The pharmacokinetic study in dogs has shown that the recombinant canine PD-1 fusion protein exhibited a typical biphasic PK profile after intravenous infusion administration, and the linear pharmacokinetic properties were observed between 1.00 and 12.00 mg/kg. Meanwhile, the T_1/2 after intravenous infusion administration with non-compartmental analysis was about 5.79 days.

Importance of Observing the Progress Curve During Enzyme Assay in an Automated Clinical Chemistry Analyzer: A Case Study

In the case presented here the reported result for total creatine phosphokinase led to the physician calling for report confirmation. The repeated test result was in keeping with the clinical picture and thus the previous erroneous result was amended. The incorrect result from auto analyzer was identified as failure to run the sample in dilution after instrumental flagging of possible substrate exhaustion evidenced by erroneous progress curve. A frequent reason for nonlinear progress curves is the presence of excess enzyme which can be easily misinterpreted as lower enzyme activity in a provided sample. Careful inspection of progress curve and predilution of sample in anticipated cases could avoid erroneous result.

Analytical Methods for the Determination of Neuroactive Steroids

Neuroactive steroids are a family of all steroid-based compounds, of both natural and synthetic origin, which can affect the nervous system functions. Their biosynthesis occurs directly in the nervous system (so-called neurosteroids) or in peripheral endocrine tissues (hormonal steroids). Steroid hormone levels may fluctuate due to physiological changes during life and various pathological conditions affecting individuals. A deeper understanding of neuroactive steroids' production, in addition to reliable monitoring of their levels in various biological matrices, may be useful in the prevention, diagnosis, monitoring, and treatment of some neurodegenerative and psychiatric diseases. The aim of this review is to highlight the most relevant methods currently available for analysis of neuroactive steroids, with an emphasis on immunoanalytical methods and gas, or liquid chromatography combined with mass spectrometry.

Mapping the Diverse Genetic Disorders and Rare Diseases Among the Syrian Population: Implications on Refugee Health and Health Services in Host Countries

The aim of this systematic review is to provide physicians and researchers with a comprehensive list of reported genetic disorders in patients of Syrian origin-those who have become part of the largest displaced population globally-and to highlight the need to consider migrant population-based risk for the development of genetic disease control and prevention programs. This review was performed based on the 2015 PRISMA and the international prospective register of systematic reviews. The present review reports on a total of 166 genetic disorders (only 128 reported on OMIM) identified in the Syrian population. Of these disorders, 27% are endocrine-, nutritional- and metabolic-related diseases. Second to metabolic disorders are congenital malformations, deformations and chromosomal abnormalities. Diseases of the blood and the blood-forming organs accounted for 13% of the total genetic disorders. The majority of the genetic disorders reported in Syrian patients followed an autosomal recessive mode of inheritance. These findings are a reflection of the high rates of consanguineous marriages that favor the increase in incidence of these diseases. From the diseases that followed an autosomal recessive mode of inheritance, 22% are reported to be only present in Syria and other regional countries. Twelve of these genetic diseases were identified to be strictly diagnosed in individuals of Syrian origin. The present systematic review highlights the need to develop programs that target genetic disorders affecting Syrian migrants in host countries. These programs would have potential financial and economic benefits, as well as a positive impact on the physical and mental health of members of the Syrian refugee community and those of their host societies. In turn, this would decrease the burden on the health systems in host countries.

High-dose HOOK effect in urinary DcR2 assay in patients with chronic kidney disease

BACKGROUND

Urinary DcR2 (uDcR2) is a biomarker for the early detection the tubulointerstitial injury (TII) in patients with chronic kidney disease (CKD), but the high-dose hook effect may lead to falsely low or even negative results when using an enzyme-linked immunosorbent assay (ELISA). This study aimed to investigate if the high-dose hook effect exists with ELISA testing, and to uncover a potential approach for reducing this effect.

METHODS

72 CKD patients were recruited and categorized into four groups based on TII scores. uDcR2 was measured in undiluted and serially diluted (two-, four-, eight- and 16-fold dilutions) urine using an ELISA kit. The results from the assay were normalized to urinary creatinine. We evaluated the correlation between uDcR2/cre levels at different dilutions and renal histological parameters. Receiver operating characteristic (ROC) curves were generated to examine the value of uDcR2/cre for predicting TII.

RESULTS

uDcR2/cre levels in the undiluted urine were significantly higher in patients with CKD than those in the control. However, higher TII scores did not yield higher levels of uDcR2/cre in the undiluted urine. After serial dilution, uDcR2/cre levels were highest with the four-fold dilution. A positive correlation was found between uDcR2/cre levels at different dilutions and TII scores, with the highest correlation coefficient and the largest AUC being observed at the four-fold dilution.

CONCLUSIONS

The high-dose hook effect was apparent during ELISA testing of uDcR2 in CKD patients, yet dilution of the urine samples neutralized this effect. However, the use of a four-fold dilution of urine for uDcR2/cre testing may eliminate the high-dose hook effect and make it possible to effectively monitor the severity of TII in CKD patients.