Outcomes of Preoperative Transophthalmic Artery Embolization of Meningiomas: A Systematic Review with a Focus on Embolization Agent

BACKGROUND

Transophthalmic artery embolization of intracranial meningiomas is thought to be associated with a high complication risk.

PURPOSE

With advances in endovascular techniques, we systematically reviewed the current literature to improve our understanding of the safety and efficacy of transophthalmic artery embolization of intracranial meningiomas.

DATA SOURCES

We performed a systematic search using PubMed from inception until August 3, 2022.

STUDY SELECTION

Twelve studies with 28 patients with intracranial meningiomas embolized through the transophthalmic artery were included.

DATA ANALYSIS

Baseline and technical characteristics and clinical and safety outcomes were collected. No statistical analysis was conducted.

DATA SYNTHESIS

The average age of 27 patients was 49.5 (SD, 13) years. Eighteen (69%) meningiomas were located in the anterior cranial fossa, and 8 (31%), in the sphenoid ridge/wing. Polyvinyl alcohol particles were most commonly (n = 8, 31%) used to preoperatively embolize meningiomas, followed by n-BCA in 6 (23%), Onyx in 6 (23%), Gelfoam in 5 (19%), and coils in 1 patient (4%). Complete embolization of the target meningioma feeders was reported in 8 (47%) of 17 patients; partial embolization, in 6 (32%); and suboptimal embolization, in 3 (18%). The endovascular complication rate was 16% (4 of 25), which included visual impairment in 3 (12%) patients.

LIMITATIONS

Selection and publication biases were limitations.

CONCLUSIONS

Transophthalmic artery embolization of intracranial meningiomas is feasible but is associated with a non-negligible complication rate.

Surfactant: clinical applications

Pulmonary surfactant is an important chemical component of the lung. It decreases surface tension in the alveolar cells to help stabilize the alveoli, and it may help prevent pulmonary edema. Currently, naturally and synthetically derived surfactants are being used to treat neonatal respiratory distress syndrome, a leading cause of death in premature infants. Surfactant is recommended for prophylactic therapy in infants weighing less than 1,350 g (3 lb) and in infants weighing more than 1,350 g who show signs of pulmonary immaturity and for rescue therapy in infants with respiratory distress syndrome. Surfactant is administered by endotracheal tube, and the recommended dose is 5 mg per kg. Three doses, given 12 hours apart, is the recommended regimen for prophylactic therapy. Rescue therapy consists of one dose of surfactant given at the onset of respiratory distress and another dose given 12 hours later.

Synthesis and subcellular localization of the murine coronavirus nucleocapsid protein

The synthesis and processing of the nucleocapsid protein (pp60) of the JHM strain of murine coronaviruses were examined. Pulse-chase experiments showed that pp60 was synthesized initially as a protein of approximately 57,000 in molecular weight (p57). Immunoprecipitation using mouse anti-JHMV antiserum indicated that p57 was virus specific. Immunoprecipitation with monoclonal antibodies specific for pp60 showed that p57 was antigenically related to pp60 and was not phosphorylated, while the intracellular protein that comigrated with the virion nucleocapsid protein, pp60, was phosphorylated. The p57 was found exclusively in the cytosol while the majority of pp60 was associated with the membrane fraction but pp60 was not an integral membrane protein.

Presence of leader sequences in the mRNA of mouse hepatitis virus

To determine the structure and the mechanism of synthesis of mouse hepatitis virus mRNA, the map positions of the large RNase T1-resistant oligonucleotides of the seven mouse hepatitis virus strain A59 intracellular mRNA species were studied. We found that all but one of the oligonucleotides were mapped at the positions within each mRNA consistent with the nested-set, stairlike structure of mouse hepatitis virus mRNA (Lai et al., J. Virol. 39:823-834). However, one oligonucleotide, 10, was mapped near the 5' ends of every mRNA and virion genomic RNA. In other words, oligonucleotide 10 and, therefore, the sequences around the 5' ends of the mRNAs are not colinear with the genomic sequences. Because this oligonucleotide is present only once in the genomic RNA, this result indicates that oligonucleotide 10 is not transcribed from multiple sites on the genomic template, but rather represents a leader RNA sequence which is joined to the body sequences of the different mRNAs during mRNA transcription. This provides the most direct evidence thus far for the presence of leader sequences in the mRNAs of mouse hepatitis virus, which is a cytoplasmic virus. Several possible mechanisms of RNA synthesis are discussed.

Replication of mouse hepatitis virus: negative-stranded RNA and replicative form RNA are of genome length

There are seven virus-specific mRNA species in mouse hepatitis virus-infected cells (Lai et al., J. Virol. 39:823-834, 1981). In this study, we examined virus-specific negative-stranded RNA to determine whether there are corresponding multiple negative-stranded RNAs. Intracellular RNA from mouse hepatitis virus-infected cells was separated by agarose gel electrophoresis, transferred to nitrocellulose membranes, and hybridized to positive-stranded genomic 60S [32P]RNA. Only a single RNA species of genomic size was detected under these conditions. This RNA was negative stranded. No negative-stranded subgenomic RNA was detected. We also studied double-stranded replicative-form RNA in the infected cells. Only one replicative-form of genomic size was detected. When the double-stranded RNA isolated without RNase treatment was analyzed, again only one RNA species of genomic size was detectable. Furthermore, most of the virus-specific mRNAs could be released from this RNA species upon heating. These results suggest that all of the mouse hepatitis virus-specific RNAs are transcribed from a single species of negative-stranded RNA template of genomic size.

Characterization of two RNA polymerase activities induced by mouse hepatitis virus

RNA-dependent RNA polymerase activity was found in mouse hepatitis virus strain A59 (MHV-A59)-infected cells. The enzyme was induced in the infected cells and could not be detected in the MHV-A59 virion. Two peaks of RNA polymerase activity, one early and the other late in infection, were detected. These polymerase activities were in temporal sequence with early and late virus-specific RNA synthesis. Both of them were found to be associated with membrane fractions. There were significant differences in the enzymatic properties of the two polymerases. The early polymerase, but not the late polymerase, could be activated by potassium ions in the absence of magnesium ions and also had a lower optimum pH than the late polymerase. It was therefore probable that the enzymes represent two different species of RNA polymerase and perform different roles in virus-specific RNA synthesis. The effects of cycloheximide on MHV-specific RNA synthesis were determined. Continuous protein synthesis was required for both early and late RNA synthesis and might also be required for shutoff of early RNA synthesis.

Further characterization of mRNA's of mouse hepatitis virus: presence of common 5'-end nucleotides

The mouse hepatitis virus strain A59 codes for seven RNA species in the infected cells. These virus-specific RNAs were found to be polysome associated and therefore likely to represent mRNA's. All of them have common 3'-end sequences (Lai et al., J. Virol. 39:823-834, 1981). Their structure was further studied with respect to their 5'-end sequences. It was found that all of these mRNA's contained cap structures at their 5' ends. Furthermore, the cap-containing oligonucleotides which represent the sequences immediately adjacent to the 5' ends were found to be the same for most, if not all, of the seven virus-specific mRNA's. These sequences are also identical to the 5'-end sequences of the virion RNA genome. The 5'-end sequences were tentatively determined to be 5'-cap-N-UAAG. The presence of the common nucleotides in all of the virus-specific RNAs in mouse hepatitis virus strain A59 suggests several possible mechanisms of synthesis for these RNAs. The significance of these findings is discussed.

Mouse hepatitis virus A59: mRNA structure and genetic localization of the sequence divergence from hepatotropic strain MHV-3

The composition and structure of the mouse hepatitis virus (MHV)-specific RNA in actinomycin D-treated, infected L-2 cells were studied. SEven virus-specific RNA species with molecular weights of 0.6 X 10(6), 0.9 X 10(6), 1.2 X 10(6), 1.5 X 10(6), 3.0 X 10(6), 4.0 X 10(6), and 5.4 X 10(6) (equivalent to the viral genome) were detected. T1 oligonucleotide fingerprinting studies suggested that the sequences of each RNA species were totally included within the next large RNa species. The oligonucleotides of each RNA species were mapped on the 60S RNA genome of the virus. Each RNA species contained the oligonucleotides starting from the 3' end of the genome and extending continuously for various lengths in the 3' leads to 5' direction. All of the viral RNA species contained a polyadenylate stretch of 100 to 130 nucleotides and probably identical sequences immediately next to the polyadenylate. These data suggested that the virus-specific RNAs are mRNA's and have a stairlike structure similar to that of infectious bronchitis virus, an avian coronavirus. A proposal is presented, based on the mRNA structure, for the designation of the genes on the MHV genome. Using this proposal, the sequence differences between A59, a weakly pathogenic strain, and MHV-3, a strongly hepatotropic strain, were localized primarily in mRNA's 1 and 3, corresponding t genes A and C.