Adaptation of commercial immunoassays to analysis of complex biological substances

Simultaneous analysis of multiple serum proteins adhering to the surface of medical grade polydimethylsiloxane elastomers

Although polydimethylsiloxane (PDMS, silicone) elastomers are presumed to be chemically inert and of negligible toxicity, they induce a prompt acute inflammatory response with subsequent fibrotic reactions. Since local inflammatory and fibrotic side effects are associated with the proteinaceous film on the surface of silicone implants, the process of protein adherence to silicone is of practical medical relevance, and interesting from theoretical, clinical and biotechnological perspectives. It is hypothesized that the systemic side effects resembling rheumatoid and other connective tissue diseases may be triggered by local immunological changes, but this functional relationship has yet to be defined. Because the proteinaceous film on the surface of silicone has been identified as a key player in the activation of host defense mechanisms, we propose a test system based on a proteomics screen to simultaneously identify proteins adsorbed from serum to the surface of silicone. Herein, we describe protein adsorption kinetics on the surface of silicone implants, correlate the adhesion properties of serum proteins with the occurrence of adverse reactions to silicone, and successfully discriminate their signature on the silicone surface in a blinded study of patients suffering from fibrotic reactions (as determined by Baker scale) to silicone implants.

Significance of thyroid blood flow as a predictor of methimazole sensitivity in untreated hyperthyroid patients with Graves' disease

OBJECTIVE

The peak systolic velocity (PSV) of the inferior thyroid artery (ITA) is increased in untreated hyperthyroid patients with Graves' disease (GD). We investigated the clinical significance of the ITA-PSV and its determinants in hyperthyroid GD patients.

PATIENTS AND METHODS

ITA-PSV, together with thyroid volume, was measured by ultrasonography in untreated hyperthyroid GD patients (n=49) and healthy subjects (n=22). Established markers of GD activity such as TSH receptor antibody (TRAb), thyroid stimulating antibody (TSAb), vascular endothelial growth factor (VEGF) and immunoglobulin E (IgE) were simultaneously determined.

RESULTS

ITA-PSV, thyroid volume, VEGF and IgE were significantly higher in hyperthyroid GD patients than in normal subjects. ITA-PSV in hyperthyroid GD patients was correlated positively with serum levels of FT(3), FT(4) and IgE, smoking index and thyroid volume, and negatively with total, HDL- and LDL-cholesterols, but did not correlate significantly with age, triglyceride, TRAb, TSAb or VEGF. In stepwise regression analysis, ITA-PSV showed significant positive and negative associations with IgE and LDL-cholesterol, respectively, in hyperthyroid GD patients. In the pre-treatment hyperthyroid state, FT(4) and ITA-PSV, but not IgE, were found to be significantly and positively associated with the maintenance dose of methimazole (MMI) required to keep serum TSH within normal range for at least 12 months.

CONCLUSION

These results suggest that ITA-PSV in untreated hyperthyroid GD patients may reflect GD activity and thus MMI sensitivity.

The significance of thyroid blood flow at the inferior thyroid artery as a predictor for early Graves' disease relapse

OBJECTIVE

We investigated the clinical usefulness of thyroid blood-flow measurement in predicting relapse of Graves' disease (GD) in comparison with known risk factors for GD relapse.

MEASUREMENT

Thyroid blood flow was measured in pulsed Doppler mode at the inferior thyroid artery (ITA), and the peak systolic velocity (PSV) calculated.

PATIENTS

ITA-PSV was measured in euthyroid GD patients (n = 79) immediately before withdrawal of anti-thyroid drug (ATD) and in healthy subjects (n = 17).

RESULTS

In the 79 euthyroid GD patients, the values of free triiodothyronine (FT3), TSH receptor autoantibody (TRAb), ITA-PSV and thyroid volume were significantly higher in the relapse group (n = 40) than in the nonrelapse group (n = 39) and the Youden index of ITA-PSV was significantly higher than that of FT3, TSH, TRAb and vascular endothelial growth factor (VEGF).

CONCLUSION

ITA-PSV may assist in the prediction of early GD relapse after ATD withdrawal.

In vitro degradation of the antimicrobial human peptide HEM-γ 130–146 in plasma analyzed by a validated quantitative LC–MS/MS procedure

In stability studies during preclinical drug development, the human antimicrobial peptide hHEM-gamma 130-146 shows progressive N-terminal degradation in plasma. To determine this effect, we developed and validated a selective and quantitative muHPLC-MS/MS procedure for this compound. Following deproteinization by precipitation, reversed-phase separation is performed with a time-saving two-column design online coupled to an ion trap mass spectrometer for electrospray ionization MS detection. Using a linear calibration curve obtained with synthetic external standards ranging nearly two orders of magnitude, we achieved good precision (repeatability and reproducibility: 5-15%), accuracy (-3 to 15%), and ruggedness with a lower limit of quantification at 0.29 microg/ml plasma (0.15 microM). Because of good linearity (r2>0.999), the recovery (84+/-3%) and ion suppression (86+/-4% remaining intensity) were calculated from specifically prepared calibration curves. The developed procedure was applied to human and animal plasma samples. Incubations in the presence and absence of proteinase inhibitors revealed at least an aminopeptidase M activity for the initial N-terminal truncation of tryptophan (W130) and a putative glutaminyl-peptide cyclotransferase activity for the resulting intermediate starting with the bared glutamine residue (Q131). The calculated periods of half-change demonstrated exceeding interspecies variations, whereas the intraspecies variations were only between 20 and 30%. The current procedure is valuable as a generic method for pharmaceutical purposes, and data give important information for further development toward a potential natural drug candidate.