An improved radioimmunoassay for measurement of pepsinogen in porcine blood samples

Anthracycline-Functionalized Dextran as a New Signal Multiplication Tagging Approach for Immunoassay

The most used kind of immunoassay is enzyme-linked immunosorbent assay (ELISA); however, enzymes suffer from steric effects, low stability, and high cost. Our research group has been developing quinone-linked immunosorbent assay (QuLISA) as a new promising approach for stable and cost-efficient immunoassay. However, the developed QuLISA suffered from low water-solubility of synthesized quinone labels and their moderate sensitivity. Herein, we developed a new approach for signal multiplication of QuLISA utilizing the water-soluble quinone anthracycline, doxorubicin, coupled with dextran for signal multiplication. A new compound, Biotin-DexDox, was prepared in which doxorubicin was assembled on oxidized dextran 40, and then it was biotinylated. The redox-cycle-based chemiluminescence and the colorimetric reaction of Biotin-DexDox were optimized and evaluated, and they showed very good sensitivity down to 0.25 and 0.23 nM, respectively. Then, Biotin-DexDox was employed for the detection of biotinylated antibodies utilizing avidin as a binder and a colorimetric assay of the formed complex through its contained doxorubicin redox reaction with NaBH₄ and imidazolium salt yielding strong absorbance at 510 nm. The method could detect the plate-fixed antibody down to 0.55 nM. Hence, the application of Biotin-DexDox in QuLISA was successfully demonstrated and showed a significant improvement in its sensitivity and applicability to aqueous assays.

A point-of-care chemiluminescence immunoassay for pepsinogen I enables large-scale community health screening

Pepsinogen I (PGI) can reflect the morphology and function of the gastric mucosa. Accordingly, the large-scale community health screening of PGI can dramatically increase the early diagnosis rate of gastric cancer. However, PGI testing can only be carried out in comprehensive hospitals and health examination centers. To ameliorate this issue, a point-of-care chemiluminescent immunoassay for PGI was developed in a fully automated miniaturized instrument. This instrument was especially developed for health check-ups in the grassroots communities; its volume of which is only 0.18 m³. Critically, the entire detection process for a single sample only requires 20 min, and the samples can be loaded continuously, making the method suitable for high-throughput analysis. The assay displayed an excellent detection limit of 0.048 ng/mL with a broad detection range of 0-200 ng/mL. Furthermore, this assay exhibited high sensitivity and specificity, had low intra- and inter-assay coefficients of variation (<10%), and was not affected after storage at 37 °C for 7 days. The assay was used to detect PGI in 95 clinical serum samples, and the results were highly correlated with those that were clinically tested (correlation coefficient, R² = 0.998). Hence, the method established in this work has great application value and can be broadly applied for the large-scale screening of gastric cancer in resource-limited areas.

Serum pepsinogen-A, canine pancreatic lipase immunoreactivity, and C-reactive protein as prognostic markers in dogs with gastric dilatation-volvulus

BACKGROUND

Pepsinogens are proenzymes secreted by gastric chief cells. In humans, their serum concentrations reflect gastric mucosal morphological and functional status.

OBJECTIVES

To evaluate serum canine pepsinogen-A (cPG-A), C-reactive protein (CRP), and canine pancreatic lipase immunoreactivity (cPLI) concentrations in dogs with gastric dilatation-volvulus (GDV).

ANIMALS

Sixty-six dogs presented with GDV and 79 healthy controls.

METHODS

Blood was collected prospectively, and records retrospectively reviewed.

RESULTS

Median cPG-A concentration was higher in GDV dogs (median, 397 μg/L; range, 37-5,410) compared to controls (median, cPG-A 304 μg/L; range, 18-848; P = .07). Mortality rate in GDV dogs was 22.7%. In nonsurvivors of GDV, median cPG-A was higher compared to survivors (median, 746 μg/L; range, 128-5,409 versus median, 346; range, 36-1,575, respectively; P = .003). The proportion of dogs with increased cPG-A increased with gastric wall damage score (P = .007). An ROC analysis of cPG-A as a predictor of death showed an area under the curve (AUC) of 0.75, higher than lactate (AUC 0.66), and corresponded to a sensitivity and specificity of 53% and 88%, respectively. CRP was increased in 48 dogs (75%), cPLI was >200 μg/L in 26 dogs (39.4%) and >400 μg/L in 12 dogs (18.2%) but both analytes had no association with outcome.

CONCLUSIONS

Presurgical cPG-A concentration was positively and significantly associated with gastric wall lesion severity, but, based on ROC analysis, it was only a moderate outcome predictor. CRP and cPLI were commonly increased in dogs with GDV.

Simultaneous detection of different serum pepsinogens and its primary application

AIM: To develop the simple, rapid and sensitive dual-label time-resolved fluoroimmunoassay for pepsinogens in human serum.

METHODS: Based on two-site sandwich protocol, monoclonal antibodies (McAbs) against pepsinogen I (PG I) and PG II were co-coated in 96 microtitration wells, and tracer McAbs against PG I and PG II were labeled with europium (Eu) and samarium (Sm) chelate, respectively. Diluted serum samples of Eu³⁺- and Sm³⁺-McAbs were added into microtitration wells simultaneously. After washing, fluorescence of bound Sm³⁺ and Eu³⁺ tracers was detected.

RESULTS: The detection limit was 0.2 μg/L for PG I and 0.05 μg/L for PG II. The assay range was 5.0-320.0 μg/L for PG I and 1.0-55.0 μg/L for PG II. The average recovery rate was 102.7% for PG I and 98.8% for PG II. Sera from healthy controls and patients with gastric disease were analyzed. The PG detected by dual-label assay was in good agreement with that detected by single-label assay or by enzyme-linked immunosorbent assay.

CONCLUSION: Dual-label assay can provide high-throughput serological screening for gastric diseases.

Correlation of five radioimmunoassay systems for measurement of bovine plasma pregnancy-associated glycoprotein concentrations at early pregnancy period

The measurement of serum or plasma PAG concentrations is currently used as a specific method for pregnancy diagnosis in cattle. In this study, the correlation between five radioimmunoassay systems (RIA-497, RIA-706, RIA-780, RIA-809 and RIA-Pool) developed for measurement of PAG concentrations in ruminant species was investigated in plasma from pregnant Friesian Holstein females. Plasma PAG concentrations (ng/mL) measured by different RIA systems were significantly correlated between them ( > or = 0.81; P<0.001). PAG concentrations increased significantly from Day 21 (n=27) to 30 (n=37) after AI by use of all PAG-RIA systems. From Day 30 to 80 after AI, lower PAG concentrations were observed when using the homologous system RIA-497. The addition of several proteinase inhibitors changed neither the non specific binding nor the B(0) binding to the tracer. Our results suggest that all tested PAG-RIA (RIA-497, RIA-706, RIA-780, RIA-809 and RIA-Pool) are highly correlated and can be useful to follow PAG concentrations in samples collected during the first trimester of gestation.

Enteral feeding induces diet-dependent mucosal dysfunction, bacterial proliferation, and necrotizing enterocolitis in preterm pigs on parenteral nutrition

Preterm neonates have an immature gut and metabolism and may benefit from total parenteral nutrition (TPN) before enteral food is introduced. Conversely, delayed enteral feeding may inhibit gut maturation and sensitize to necrotizing enterocolitis (NEC). Intestinal mass and NEC lesions were first recorded in preterm pigs fed enterally (porcine colostrum, bovine colostrum, or formula for 20-40 h), with or without a preceding 2- to 3-day TPN period (n = 435). Mucosal mass increased during TPN and further after enteral feeding to reach an intestinal mass similar to that in enterally fed pigs without TPN (+60-80% relative to birth). NEC developed only after enteral feeding but more often after a preceding TPN period for both sow's colostrum (26 vs. 5%) and formula (62 vs. 39%, both P < 0.001, n = 43-170). Further studies in 3-day-old TPN pigs fed enterally showed that formula feeding decreased villus height and nutrient digestive capacity and increased luminal lactic acid and NEC lesions, compared with colostrum (bovine or porcine, P < 0.05). Mucosal microbial diversity increased with enteral feeding, and Clostridium perfringens density was related to NEC severity. Formula feeding decreased plasma arginine, citrulline, ornithine, and tissue antioxidants, whereas tissue nitric oxide synthetase and gut permeability increased, relative to colostrum (all P < 0.05). In conclusion, enteral feeding is associated with gut dysfunction, microbial imbalance, and NEC in preterm pigs, especially in pigs fed formula after TPN. Conversely, colostrum milk diets improve gut maturation and NEC resistance in preterm pigs subjected to a few days of TPN after birth.

Antimicrobial treatment reduces intestinal microflora and improves protein digestive capacity without changes in villous structure in weanling pigs

The immediate post-weaning period is often associated with gut malfunction and diarrhoea for young pigs. Administration of antimicrobials remains an effective way to control weaning diarrhoea but it remains unclear how they affect gut physiology and microbiology although this is a prerequisite for being able to devise better alternatives. Hence, for 7 d we treated pigs, weaned at 24 d of age, with a combination of amoxicillin (25 mg/kg feed and injection of 8.75 mg/kg body weight per 12 h) and ZnO (2.5 g/kg feed). The pigs treated with antimicrobials (n 11) showed no signs of gut malfunction at any time, whereas untreated weaned controls (n 11) developed clinical diarrhoea. The antimicrobial treatment resulted in a higher daily weight gain compared with weaned controls (101 v. -44 g/d, P < 0.0001), whereas both groups had a similar degree of villous atrophy compared with unweaned 24-d-old controls (n 8; P < 0.05). The antimicrobial treatment gave a dramatic reduction in small intestinal microbial diversity, and specifically prevented tissue colonization with Escherichia coli compared with weaned controls. Further, the antimicrobial treatment improved amylase, trypsin and small intestinal aminopeptidase A and N activities (all P < 0.05). Specifically for the colon, the antimicrobial treatment was associated with reduced tissue weight ( -23 %, P < 0.05), reduced concentration of SCFA (P < 0.05), and increased mucosal goblet cell area (P < 0.0001) compared with weaned controls. We conclude that the beneficial effects of antimicrobials are mediated not only through reduction in intestinal bacterial load, but also through a stimulation of protein digestive function and goblet cell density.

Ultrasensitive detection of pepsinogen I and pepsinogen II by a time-resolved fluoroimmunoassay and its preliminary clinical applications

A fast and highly sensitive assay for pepsinogen I (PG I) and pepsinogen II (PG II) by using time-resolved fluoroimmunoassay (TRFIA) detection technique has been developed for the determination of serum PG I and PG II against gastrointestinal diseases. On the noncompetitive assay, one monoclonal antibody (McAb) coated on wells was directed against a specific antigenic site on the PG I or PG II. The McAb, called as labelling McAb, was prepared with the europium-chelate of N-(p-isothiocyanatobenzyl)-diethylenetriamine-N,N,N,N-tetraacetic acid and directed against a different antigenic site on the PG I or PG II molecule. After bound/free separation by washing, the fluorescence counts of bound Eu(3+)-McAb were measured. The levels of PG in sera from patients or healthy volunteers were determined by PG I and PG II TRFIA using the autoDELFIA(1235) system. The measurement ranges of PG I-TRFIA were 3.5-328.0 microg L(-1) and those of PG II-TRFIA were 2.0-55.0 microg L(-1). The within-run and between-run CVs of the PG I-TRFIA were 1.9% and 4.7%, respectively, and those of PG II-TRFIA were 2.1% and 3.8%, respectively. The recovery rates of PG I-TRFIA and PG II-TRFIA were 102.7% and 104.6%, respectively. The detection limitations of PG I and PG II were 0.05 microg L(-1) and 0.02 microg L(-1), respectively. The dilution experiments showed the percentage of expected value of PG I-TRFIA was 93.2-102.3% and of PG II-TRFIA was 97.3-110.6%. The cross-reacting rate between PG I and PG II was negligible. The linear correlation of radioimmunoassay (RIA) and TRFIA measurements resulted in a correlation coefficient as 0.926 of PG I and as 0.959 of PG II. The europium-labelling McAbs were stable for at least one year at -20 degrees C, and the results of the TRFIA with same reagents were reproducible over one year as well. The means of 1600 healthy volunteers were 162.4+/-52.1 microg L(-1) for serum PG I, 11.7+/-6.8 microg L(-1) for serum PG II, and 13.8+/-7.4 for the PG I/PG II ratio. The normal ranges of Serum PG I levels for healthy volunteers were 58.2-266.6 microg L(-1), and those of serum PG II levels were less than 25.3 microg L(-1). The availability of a highly sensitive, reliable, and convenient PG-TRFIA method for quantifying PG will allow investigations into the possible diagnostic value of this analysis in various clinical conditions, including gastric carcinoma, duodenal ulcer, gastric ulcer and gastritis. The sensitivity and reproducibility of the assay were satisfactory for clinical applications.

Correlation between a proteolytic method and a radioimmunoassay for porcine serum pepsinogen concentrations

The measurement of serum pepsinogen concentrations by enzymatic method and immunoassay provides diagnostic values and should be helpful in the detection of gastric diseases related to a rise of blood pepsinogen. In the present study, the correlation between a conventional enzymatic method and a recently developed radioimmunoassay (RIA) for serum pepsinogen A was investigated. A total of 123 sera samples of porcine foetuses (n = 28), adult healthy pigs (n = 56), pigs with parakeratosis (n = 25) and pigs with ulceration of the pars oesophagea (n = 14) were tested. Overall, there was a slight correlation between the two methods (r = 0.60). In relation to individual animal groups, the correlations (r) were 0.39 (P>0.05), 0.74 (P<0.001), 0.19 (P>0.05) and 0.34 (P>0.05) in foetuses, healthy pigs, pigs with parakeratosis and pigs with ulcers, respectively. In both methods, pepsinogen concentrations (means+/-SE) were significantly higher (P<0.05) in pigs with parakeratosis (1778 +/- 86.00 mUTyr/L; 690 +/- 53.00 ng/mL) and in pigs with ulcers (2026 +/- 153.00 mUTyr/L; 1747 +/- 94.00 ng/mL) when compared to healthy pigs (935 +/- 58.00 mUTyr/L; 275 +/- 35.00 ng/mL). The proteolytic method gave a significant increased activity (P<0.05) in foetuses (1150 +/- 82.00 mUTyr/L) vs. (935 +/- 58.00 mUTyr/L) in healthy adult pigs, indicating an additional proteolytic activity in the sera of foetuses or neonates.

Survey of gastric lesions and blood pepsinogen levels in pigs in Burkina Faso

The purpose of the study was to investigate the prevalence of gastric lesions and to provide diagnostic values for serum pepsinogen in non-infected pigs and in pigs with gastric disease. In an abattoir survey, the pepsinogen concentrations were measured in the serum from 62 non-infected pigs, 33 pigs with gastric lesions and 17 pigs infected with Hyostrongylus rubidus, using a specific radioimmunoassay (RIA). The mean (+/- SE) pepsinogen concentrations in the serum of non-infected pigs, in pigs with gastric ulcers, and in pigs with a heavy H. rubidus infection were 630.8 +/- 39.2 ng/ml, 1084.5 +/- 166.2 ng/ml and 1095.2 +/- 102.3 ng/ml, respectively (p<0.05). Because of the higher concentrations of pepsinogen in the blood of pigs with gastric ulcers or parasitic infections, it is suggested that the measurement of serum pepsinogen by RIA may be an effective biochemical approach to the diagnosis of chronic gastric disorders in pigs.