Prevalence of occult hepatitis B infection among blood donors in Saint Petersburg

The aim of this study was to assess the prevalence of occult hepatitis B infection among blood donors in St. Petersburg, as well as to characterize the identified virus isolates. The study material was represented by 2800 blood plasma samples collected in 2019 from blood donors living in St. Petersburg. The ELISA study for HBV marker rate consisted of HBsAg, anti-HBs IgG, anti-HBcore IgG. HBV DNA was analyzed by nested PCR with real-time hybridization-fluorescence detection on three targets allowing to determine virus DNA at low viral load, including HBsAg-negative chronic hepatitis B. Hepatitis B serological markers were detected in 69.43% of those surveyed, HBsAg was found in 0.43% of individuals, and all of which donated blood first time. A significant excess of the anti-HBcore IgG antibodies occurrence among primary donors (15.1%) compared with repeated/regular donors (7.48%) was shown. The prevalence of virus DNA in the group was 3.14%, including 2.71% of cases in HBsAg-negative CHB. Based on phylogenetic analysis of 88 isolates, HBV subgenotypes were determined in the following order: D1 and D2, 40.91% each, D3 and A2, 9.09% each. While determining the serological subtype in detected isolates, the serotype ayw3 (52.27%) vs ayw2 (46.59%) and adw2 (10.23%) prevailed. Drug resistance mutations, including compensatory ones, were detected in six examined patients (6.82%). In all genotype D isolates, multiple amino acid substitutions were identified in the RT, SHB, MHB, LHB, and Core regions; mutations in the preCore region were detected in 21.59% samples. In the MHR of the HBV genotype D genome, twenty-six positions were identified in which amino acid substitutions occurred, and all isolates showed modifications at positions 113, 114, 131, 134, 159, 161, 168, in 76 — at position 122, in 68 — at position 127, in 36 — at position 118, in 24 — at position 128. In HBV A2 isolates, mutations T113S, S143T, Y161F were identified. Nine isolates in the preCore region showed a polymorphism including a stop codon W28*W; in five isolates the W28S substitution was shown in the same position, and the W28*S variant was found in one more sample. The high incidence of HBsAg-negative CHB cases among blood donors, as well as the predominance of HBV isolates that simultaneously carry mutations resulting in diagnostic failure of HBsAg tests and prophylactic failure of immunoglobulin or vaccines and virus reactivation, mutations that contribute to disease progression obviously pose a threat to health and require to be further examined

Loss of signal during intraoperative neuromonitoring of laryngeal nerves as a predictor of postoperative larynx paresis: Analysis of 1065 consequetive thyroid and parathyroid operations. Surgeons' algorythm (tactics)

During thyroid and parathyroid operations performed with laryngeal nerves neuromonitoring, a segmental or global loss of signal may occur. The most frequent cause of loss of signal – is tension of thyroid gland tissue and at the same time tension of the laryngeal nerves. There is no consensus if this complication arises regarding surgeon’s actions. Aim. Evaluation of predictive value of loss of signal during IONM regarding larynx paresis in postoperative period, and algorithm suggestion in case of loss of signal develops. Materials and methods. 1065 patients were operated on thyroid and parathyroid glands with neuromonitoring of laryngeal nerves. Neuromonitore C2 (Inomed, Emmendingen, Germany) was used. We evaluated frequency of loss of signal, described types of loss of signal, showed sensitivity and specificity of loss of signal and development of postoperative larynx paresis. Results. Loss of signal developed in 32 (1,9%) patients. More frequently loss of signal was detected at left side (p=0,01, χ2 = 4,2 OR=2,9). Sensitivity (Se)  of loss of signal and postoperative larynx paresis development reached 59,2%, specificity – 99,7% (Sp), positive predicitive value (PPV) – 91,4%, negative predictive value (NPV) – 97,8%. There are no statistically reliable differences in recovery periods of larynx function depending on type of loss of signal (segmental or global) (p=0,5). Conclusions. In most cases loss of electromyographical signal indicates injury of laryngeal nerves during operation on thyroid and parathyroid glands. When there is loss of signal in case of bilateral thyroid gland disease it is reasonable to make a decision to stop operation to prevent development of bilateral larynx paresis