Novel use of a closed-tip stent retriever to prevent distal embolism in the posterior circulation: illustrative case.

BACKGROUND: In mechanical thrombectomy for tandem occlusions in vertebrobasilar stroke, distal emboli from the vertebral artery lesion should be prevented. However, no suitable embolic protection devices are currently available in the posterior circulation. Here, the authors describe the case of a vertebral artery lesion effectively treated with a closed-tip stent retriever as an embolic protection device in the posterior circulation. OBSERVATIONS: A 65-year-old male underwent mechanical thrombectomy for basilar artery occlusion, with tandem occlusion of the proximal vertebral artery. After basilar artery recanalization via the nonoccluded vertebral artery, a subsequent mechanical thrombectomy was performed for the occluded proximal vertebral artery. To prevent distal embolization of the basilar artery, an EmboTrap III stent retriever was deployed as an embolic protection device within the basilar artery to successfully capture the thrombus. LESSONS: A stent retriever with a closed-tip structure can effectively capture thrombi, making it a suitable distal embolic protection device in the posterior circulation.

Clinical evaluation of mechanical thrombectomy for patients with posterior circulation occlusion: A retrospective study.

OBJECTIVE: Although consensus has been reached regarding the use of mechanical thrombectomy for acute large anterior circulation occlusion, its effectiveness in patients with posterior circulation occlusion remains unclear. This study aimed to establish the determining factors for good clinical outcomes of mechanical thrombectomy for posterior circulation occlusion. METHODS: We extracted cases of acute large vessel occlusion (LVO) in the posterior circulation from a database comprising 536 patients who underwent mechanical thrombectomy at our hospital between April 2015 and March 2021. RESULTS: Fifty-two patients who underwent mechanical thrombectomy for LVO in the posterior circulation were identified. Five patients with simultaneous occlusion of the anterior and posterior circulation were excluded; finally, 47 patients were included in this study. The median patient age was 78 years, and 36% of the patients were women. The median National Institutes of Health Stroke Scale (NIHSS) score on admission was 31, the median posterior circulation-Alberta Stroke Program Early Computed Tomography Score (pc-ASPECTS) was 8, and the median Basilar Artery on Computed Tomography Angiography (BATMAN) score was 6. The rate of good recanalization (Thrombolysis in Cerebral Infarction scale grades 2b and 3) was 96%, and a good prognosis (modified Rankin Scale score of 0-2 at 90 days) was achieved in 19 patients (40%). The median pc-ASPECTS was significantly higher in the good prognosis group than in the poor prognosis group (10 vs. 7; p = 0.007). The median NIHSS score at presentation was significantly lower in the good prognosis group than in the poor prognosis group (17 vs. 34; p = 0.02). The median BATMAN score was significantly higher in the good prognosis group than in the poor prognosis group (8 vs. 3.5; p = 0.0002). Multivariate analysis showed that an NIHSS score ≦ 20 at presentation was the only independent factor for good prognoses. CONCLUSION: The prognosis of mechanical thrombectomy for posterior circulation LVO was better in patients with lower NIHSS scores at presentation.

Transduction of a Neospora caninum antigen gene into mammalian cells using a modified Bombyx mori nucleopolyhedrovirus for antibody production.

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) can easily enter and transduce foreign genes into mammalian cells, but these functions are difficult for Bombyx mori nucleopolyhedrovirus (BmNPV). In this study, we investigated the induction of antibody production in mice immunized with an engineered BmNPV. The GP64 of BmNPV (BmGP64) was replaced with the GP64 of AcMNPV (AcGP64); this construct, designated BmNPVΔbgp/AcGP64, displays AcGP64 on the surface of BmNPV. The Neospora caninum antigen (NcSRS2) expression cassette, consisting of the cytomegalovirus immediate-early promoter and NcSRS2 from N. caninum, was inserted into BmNPVΔbgp/AcGP64; this construct was designated BmNPVΔbgp/AcGP64/SRS2. For comparison, AcMNPV/SRS2, which contains the same NcSRS2 expression cassette as for BmNPVΔbgp/AcGP64, was also constructed. NcSRS2 was expressed in HEK293T cells when the engineered BmNPVs were transduced at a multiplicity of infection of 150. BmNPVΔbgp/AcGP64/SRS2 induced the production of NcSRS2-specific antibodies in mice, whereas AcMNPV/SRS2 and the control BmNPV did not. These results suggest that BmNPV prepared from silkworm hemolymph induces the production of antigen-specific antibodies in immunized mice and can be used for antibody production and vaccine development.

Evaluation of recombinant Neospora caninum antigens purified from silkworm larvae for the protection of N. caninum infection in mice.

Three antigens (NcSAG1, NcSRS2 and NcMIC3) from Neospora caninum were expressed using the BmNPV bacmid system in silkworm larvae and purified from the hemolymph. From 20 silkworm larvae, 1.5, 1.2 and 1.4 mg of purified recombinant NcSAG1, NcSRS2 and NcMIC3 were obtained, respectively. When each purified recombinant antigen was immunized with Freund's incomplete adjuvant (FIA) to mice, recombinant NcSAG1 induced a Th2 immune response in immunized mice and produced a SAG1-specific antibody. In the experiment where NcSAG1-immunized mice were challenged with N. caninum, the cerebral N. caninum burden was significantly reduced compared with that of either the FIA- or PBS-immunized mice. Recombinant NcSRS2 or NcMIC3 induced both Th1 and Th2 immune responses, but NcMIC3-immunization did not induce significant production of NcMIC3-specific antibodies. These results suggest that the silkworm can produce recombinant antigens of N. caninum, which can be used as a recombinant vaccine against N. caninum.

Bombyx mori nucleopolyhedrovirus displaying neospora caninum antigens as a vaccine candidate against N. caninum infection in mice.

Baculovirus display systems have been utilized for cell-specific gene transfer, regenerative medicine, and as vaccine vectors. In particular, baculovirus particles displaying surface antigens have been used as vaccines against some parasites and viruses. In this study, Bombyx mori nucleopolyhedrovirus (BmNPV) particles displaying Neospora caninum antigens (NcSAG1, NcSRS2, and NcMIC3) purified from the hemolymph or fat body of silkworm larvae were prepared to vaccinate mice against N. caninum. Each antigen was expressed on the surface of BmNPV particles through glycoprotein 64 transmembrane and cytoplasmic domains. Antigen-specific antibody production was induced in mice by immunization with each recombinant BmNPV particle. NcMIC3-displaying BmNPV particles purified from the fat body induced a lower antibody titer than particles purified from the hemolymph. Antigen-specific IgG2a was predominantly produced in mice by immunization with NcSAG1-displaying BmNPV particles compared to IgG1, and induction of IFN-γ was dominant, indicating that antigen-displaying BmNPV particles can elicit a Th1 immune response in mice. Semi-quantitative PCR analysis revealed that immunization with each antigen-displaying BmNPV particle partially protected mice from cerebral N. caninum infection. These results suggest that antigen-displaying BmNPV particles can provide an alternative method of controlling neosporosis in cattle and represent a new generation of N. caninum vaccines.