Biochemical Immunoassays Research Articles

Effect Evaluation of Clinical Diagnosis and Treatment of Renal Diseases by Biochemical Immunoassay

Effect Evaluation of Clinical Diagnosis and Treatment of Renal Diseases by Biochemical Immunoassay

Mirror-image streptavidin with specific binding to L-biotin, the unnatural enantiomer

The streptavidin–biotin system is known to have a very high affinity and specificity and is widely used in biochemical immunoassays and diagnostics. However, this method is affected by endogenous D-biotin in serum sample measurements (biotin interference). While several efforts using alternative high-affinity binding systems (e.g., genetically modified streptavidin and biotin derivatives) have been attempted, these efforts have all led to reduction in affinity. To solve this interference issue, the enantiomer of streptavidin was synthesized, which enabled specific binding to L-biotin. We successfully obtained a functional streptavidin molecule by peptide synthesis using D-amino acids and an in vitro folding technique. Several characterizations, including size exclusion chromatography (SEC), circular dichroism spectra (CD), and heat denaturation experiments collectively confirmed the higher-order enantiomer of natural streptavidin had been formed with comparable stability to the natural protein. L-biotin specific binding of this novel molecule enabled us to avoid biotin interference in affinity measurements using the Biacore system and enzyme-linked immunosorbent assay (ELISA). We propose the enantiomer of streptavidin as a potential candidate to replace the natural streptavidin–biotin system, even for in vivo use.

Expression of CDK6 in Stomach Cancer and the Effect of CDK4/6 Inhibitor PD-0332991 on the Function of Stomach Cancer Cells.

Objective To study the expression and prognostic value of CDK6 in stomach cancer and the function of CDK4/6 inhibitor PD-0332991 on the proliferation of stomach cancer cells. Methods Immunohistochemistry was used to detect the expression of CDK6 in stomach cancer tissues and adjacent normal tissues and to analyze the effect of CDK6 on clinicopathological parameters of stomach cancer patients. Kaplan-Meier plotter was employed to study the relationship between CDK6 and overall survival in stomach cancer. Western blot and RT-PCR were used to detect protein and gene expression of CDK6 in different cells. The effects of CDK4/6 inhibitor PD-0332991 on apoptosis and aging of stomach cancer cells were detected by flow cytometry and β-galactosidase aging staining assay. The effects of CDK4/6 inhibitor PD-0332991 on the invasion and migration of stomach cancer cells were explored by the wound healing experiment and the Transwell experiment. The supernatant of stomach cancer cells was collected, and the effect of CDK4/6 inhibitor PD-0332991 on tumor markers of stomach cancer cells was detected by biochemical immunoassay. Results (1) CDK6 was highly expressed in stomach cancer tissues and cells. (2) Abnormally elevated CDK6 expression results in shorter survival in stomach cancer patients. (3) CDK4/6 inhibitor PD-0332991 could block the proliferation of stomach cancer cells, but not stomach epithelial proliferation. PD-0332991 could inhibit the secretion of pro-GRP by MGC 823. (4) PD-0332991 could advance the development of the apoptosis and senescence of stomach cancer cells and suppressed the invasion and migration of stomach cancer cells. Conclusion CDK6 expression is elevated in gastric cancer, and the CDK4/6 inhibitor PD-0332991 can remarkably promote apoptosis and senescence of stomach cancer cells and effectively inhibit the migration and invasion of stomach cancer cells.

Serum levels of C-Terminal Telopeptide (CTX) are Associated with Muscle Function in Community-Dwelling Older Adults.

Markers of bone metabolism have been associated with muscle mass and function. Whether serum cross-linked C-terminal telopeptides of type I collagen (CTX) is also associated with these measures in older adults remains unknown. In community-dwelling older adults at high risk of falls and fractures, serum CTX (biochemical immunoassays) was used as the exposure, while appendicular lean mass (dual-energy x-ray absorptiometry) and muscle function (grip strength [hydraulic dynamometer], short physical performance battery [SPPB], gait speed, sit-to-stand, balance, Timed Up and Go [TUG]) were used as outcomes. Potential covariates including demographic, lifestyle, and clinical factors were considered in statistical models. Areas under the receiver operating characteristic (ROC) curves were calculated for significant outcomes. Two hundred and ninety-nine older adults (median age: 79 years, interquartile range: 73, 84; 75.6% women) were included. In multivariable models, CTX was negatively associated with SPPB (β = 0.95, 95% confidence interval [CI]: 0.92, 0.98) and balance (β = 0.92, 0.86, 0.99) scores, and positively associated with sit-to-stand (β = 1.02, 95% CI: 1.00, 1.05) and TUG (β = 1.03, 95% CI: 1.00, 1.05). Trend line for gait speed (β = 0.99, 95% CI: 0.98, 1.01) was in the hypothesized direction but did not reach significance. Area under the ROC curves showed low diagnostic power (<0.7) of CTX in identifying poor muscle function (SPPB: 0.63; sit-to-stand: 0.64; TUG: 0.61). In older adults, higher CTX levels were associated with poorer lower-limb muscle function (but showed poor diagnostic power for these measures). These clinical data build on the biomedical link between bone and muscle.

Elevated C-reactive protein levels in the development of type 1 diabetes.

Elevated C-reactive protein (CRP) levels have previously been described before the onset of type 2 diabetes and gestational diabetes. We hypothesized that inflammation, as reflected by elevated CRP levels, can help predict development of islet autoimmunity or type 1 diabetes. Children at risk for type 1 diabetes and followed in the Diabetes Autoimmunity Study of the Young (DAISY) had blood samples drawn and frozen serum saved at various intervals after birth. CRP was measured using a high-sensitivity sandwich enzyme immunoassay. Islet autoantibodies (IAs) were measured using biochemical immunoassays. Elevations in CRP concentrations were significantly more frequent (P < 0.01) in children who later developed type 1 diabetes (8 of 16 children) than in children negative for IAs at their last testing (3 of 26). Children with one or more positive IA were more likely to have elevated CRP concentrations (15 of 36) than IA-negative children (3 of 26; P < 0.01). The finding of elevated CRP levels in infants and young children before the onset of type 1 diabetes adds to the evidence that the disease is an immunoinflammatory disorder. The elevated CRP levels may provide an additional marker for risk of progression to type 1 diabetes.