Background: The Clauss assay is widely used to quantify blood fibrinogen levels in clinical laboratories. However, by relying on thrombin as the main reagent, the Clauss assay is susceptible to interference from thrombin inhibitors, such as heparin or direct thrombin inhibitors. Here, we developed an innovative fibrinogen assay utilizing both recombinant batroxobin (rBat) and carboxymethyl chitosan (CMCS). Methods: Various biopolymers were tested to identify a suitable candidate that could enhance rBat-induced fibrin clot formation. Chromogenic substrate hydrolysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that CMCS potentiated rBat activity. Consequently, we formulated a novel fibrinogen assay reagent, ANYFIB.C, comprising rBat and CMCS. We compared ANYFIB.C fibrinogen with an established reagent (HemosIL fibrinogen-C) with 96 clinical samples using an ACL-TOP 700 coagulation analyzer. We also evaluated the interfering effects of thrombin inhibitors on fibrinogen measurements. Results: CMCS significantly enhanced the enzymatic activity of rBat and dose-dependently reduced plasma clotting times. ANYFIB.C fibrinogen levels were comparable with those of HemosIL fibrinogen-C, with the 95% confidence intervals of the Passing–Bablok regres-sion intercept and slope being −7.4797 to 6.0185 and 0.9581 to 1.0116, respectively. Nosignificant interference was observed with heparin concentrations up to 10 U/mL or dabigatran concentrations up to 600 µg/L in the ANYFIB.C fibrinogen assays. In contrast, the HemosIL fibrinogen-C reagent demonstrated inhibitory interference at dabigatran concentrations as low as 150 µg/L. Conclusions Our results suggest that ANYFIB.C (a mixture of CMCS and rBat) can be used to measure blood fibrinogen levels effectively and protect from thrombin inhibitor interference.

Saphenous mononeuropathy is an uncommon neuropathy in clinical condition, which may incur from various surgical procedures, direct trauma, or entrapment, and most frequently involves at the adductor canal, or Hunter's canal. A 17-year old female, who was majoring in ballet, visited our rehabilitation clinic for numbness in the medial aspect of the left lower leg for the previous 9 months, without weakness. The electrodiagnostic study revealed only a delayed small potential in the left saphenous nerve. MRI examination showed soft tissue swelling in the medial side of the left knee. Accordingly, we diagnosed the patient with saphenous mononeuropathy around the knee, without lumbar plexopathy or femoral neuropathy. We report a case of saphenous mononeuropathy which developed after repetitive compression on the medial side of the knee without any other iatrogenic injury, and include a review of the relevant literature.
Female ; Femoral Neuropathy ; Humans ; Hypesthesia ; Knee ; Leg ; Mononeuropathies