A novel cDNA-uPA/SCID/Rag2-/- /Jak3-/- mouse model for hepatitis virus infection and reconstruction of human immune system

Although human hepatocyte-transplanted immunodeficient mice support infection with hepatitis viruses, these mice fail to develop viral hepatitis due to the lack of an adaptive immune system. In this study, we generated new immunodeficiency cDNA-urokinase-type plasminogen activator (uPA)/SCID/Rag2^-/- /Jak3^-/- mice and established a mouse model with both a humanized liver and immune system. Transplantation of human hepatocytes with human leukocyte antigen (HLA)-A24 resulted in establishment of a highly replaced liver in cDNA-uPA/SCID/Rag2^-/- /Jak3^-/- mice. These mice were successfully infected with hepatitis B virus (HBV) and hepatitis C virus (HCV) for a prolonged period and facilitate analysis of the effect of anti-HCV drugs. Administration of peripheral blood mononuclear cells (PBMCs) obtained from an HLA-A24 donor resulted in establishment of 22.6%-81.3% human CD45-positive mononuclear cell chimerism in liver-infiltrating cells without causing graft-versus-host disease in cDNA-uPA/SCID/Rag2^-/- /Jak3^-/- mice without human hepatocyte transplantation. When mice were transplanted with human hepatocytes and then administered HLA-A24-positive human PBMCs, an alloimmune response between transplanted human hepatocytes and PBMCs occurred, with production of transplanted hepatocyte-specific anti-HLA antibody. In conclusion, we succeeded in establishing a humanized liver/immune system characterized by an allo-reaction between transplanted human immune cells and human liver using a novel cDNA-uPA/SCID/Rag2^-/- /Jak3^-/- mouse. This mouse model can be used to generate a chronic hepatitis mouse model with a human immune system with application not only to hepatitis virus virology but also to investigation of the pathology of post-transplantation liver rejection.

Spirodecosporaceae fam. nov. (Xylariales, Sordariomycetes) and two new species of Spirodecospora

The genus Spirodecospora has been placed in Xylariaceae based on morphological similarities. Spirodecospora spp., found on bamboo in Japan, were taxonomically and phylogenetically studied using molecular data for first time. Molecular phylogenetic analyses were based on the DNA sequence data of three regions: the nuclear ribosomal internal transcribed spacer (ITS) region, the large subunit (LSU) of rDNA, and the second largest RNA polymerase II subunit (rpb2) gene. Results showed that Spirodecospora formed an independent lineage from other known families in Xylariales. The new family Spirodecosporaceae is introduced in this study to accommodate this lineage based on the phylogenetic evidence and morphological differences from the other known families. Spirodecospora is characterised by having deeply immersed ascomata with a cylindrical ostiolar neck, unitunicate, cylindrical asci with I+, wedge-shaped apical ring, and broadly ellipsoidal to fusoid, aseptate, brown, verruculose ascospores with spirally or almost straight linear ornamentation. Based on morphological observations and molecular phylogenetic analyses, S. melnikii and two new species of Spirodecospora, S. paramelnikii and S. paulospiralis, are described and illustrated. A key to the four accepted species of Spirodecospora is provided. Citation: Sugita R, Hirayama K, Shirouzu T, Tanaka K (2022). Spirodecosporaceae fam. nov. (Xylariales, Sordariomycetes) and two new species of Spirodecospora. Fungal Systematics and Evolution 10: 217-229. doi: 10.3114/fuse.2022.10.09.

Intra-Liver Allograft C3d-Binding Donor-Specific Anti-HLA Antibodies Predict Rejection After Liver Transplantation

BACKGROUND

There is no doubt that antibody-mediated rejection (AMR) due to donor-specific anti-HLA antibodies (DSA) brings a poor outcome for liver transplant recipients. However, the relationship between intragraft DSA (g-DSA), complement-binding abilities, and AMR remains unknown.

MATERIALS AND METHODS

We enrolled a total of 20 liver transplant recipients who underwent protocol or episode graft biopsies in the mid to long term after liver transplant (median 48.5, range 6-198 months), and their status of g-DSA and complement 3d (C3d)-binding abilities was assessed with the graft immunocomplex capture fluorescence analysis (ICFA) technique.

RESULTS

The prevalence of g-DSA was 15.0 % in liver transplant recipients (3/20), and serum DSA (s-DSA) also existed in 15.0% of recipients. The number of g-DSA+/s-DSA+, g-DSA+/s-DSA-, g-DSA-/s-DSA+, and g-DSA-/s-DSA- cases are 1, 2, 2, and 15, respectively. The g-DSA+ group demonstrated a significant high rejection activity index: 3.67 ± 1.53, compared with the g-DSA- group: 1.24 ± 1.15 (P = .0045). Moreover, C3d-binding reaction was notably higher in the g-DSA+ group (C3d index: 1.87 ± 0.38 vs 0.76 ± 0.35) (P < .0001). Overall, the g-DSA+ group was more associated with liver allograft rejection-not only AMR, but also T cell-mediated rejection (P = .031).

CONCLUSIONS

These results suggest that the existence of g-DSA and intragraft C3d-binding reaction had a negative impact on the liver allografts, but in contrast s-DSA did not have any significant impact.

Revision of Cerinomyces (Dacrymycetes, Basidiomycota) with notes on morphologically and historically related taxa

Cerinomyces (Dacrymycetes, Basidiomycota) is a genus traditionally defined by corticioid basidiocarps, in contrast to the rest of the class, which is characterized by gelatinous ones. In the traditional circumscription the genus is polyphyletic, and the monotypic family Cerinomycetaceae is paraphyletic. Aiming for a more concise delimitation, we revise Cerinomyces s.l. with a novel phylogeny based on sequences of nrDNA (SSU, ITS, LSU) and protein-coding genes (RPB1, RPB2, TEF1-α). We establish that monophyletic Cerinomyces s.s. is best characterized not by the corticioid morphology, but by a combination of traits: hyphal clamps, predominantly aseptate thin-walled basidiospores, and low content of carotenoid pigments. In our updated definition, Cerinomyces s.s. encompasses five well-supported phylogenetic clades divided into two morphological groups: (i-iii) taxa with arid corticioid basidiocarps, including the generic type C. pallidus; and (iv-v) newly introduced members with gelatinous basidiocarps, like Dacrymyces enatus and D. tortus. The remaining corticioid species of Cerinomyces s.l. are morphologically distinct and belong to the Dacrymycetaceae: our analysis places the carotenoid-rich Cerinomyces canadensis close to Femsjonia, and we transfer the clamps-lacking C. grandinioides group to Dacrymyces. In addition, we address genera related to Cerinomyces s.l. historically and morphologically, such as Ceracea, Dacryonaema and Unilacryma. Overall, we describe twenty-four new species and propose nine new combinations in both Cerinomycetaceae and Dacrymycetaceae.

Antibody-Mediated Rejection and Recurrent Primary Disease: Two Main Obstacles in Abdominal Kidney, Liver, and Pancreas Transplants

The advances in acute phase care have firmly established the practice of organ transplantation in the last several decades. Then, the next issues that loom large in the field of transplantation include antibody-mediated rejection (ABMR) and recurrent primary disease. Acute ABMR is a daunting hurdle in the performance of organ transplantation. The recent progress in desensitization and preoperative monitoring of donor-specific antibodies enables us to increase positive outcomes. However, chronic active ABMR is one of the most significant problems we currently face. On the other hand, recurrent primary disease is problematic for many recipients. Notably, some recipients, unfortunately, lost their vital organs due to this recurrence. Although some progress has been achieved in these two areas, many other factors remain largely obscure. In this review, these two topics will be discussed in light of recent discoveries.

Improved detection of donor-specific HLA-class II antibody in kidney transplant recipients by modified immunocomplex capture fluorescence analysis

Immunocomplex capture fluorescence analysis (ICFA) which basic principle is same as Luminex crossmatch (LXM), could detect donor-specific HLA antibody (DSA). The advantages of ICFA are (i) detection of DSA and (ii) no requirement of viable cells over the flow cytometry crossmatch (FCXM). However, FCXM has been widely used because of its higher sensitivity than ICFA, in particular HLA-class II antibody detection. In this study the accuracy of DSA detection against HLA-class II was investigated by modifying the original method of ICFA. Increment of the sensitivity was found when purified peripheral blood mononuclear cells (PBMCs) were used instead of whole blood. An ICFA-PBMC in addition to FCXM-T/B was conducted for 118 patients before kidney transplantation and 13 patients with de novo DSA against HLA-class II after transplantation. Significantly positive correlation was observed between the values of ICFA-PBMC and DSA mean fluorescence intensity (MFI) targeting class II (p < 0.0001). When the cutoff level of 1.4 was determined by receiver operating characteristic curve analysis, the average DSA MFI was found to be significantly higher in the ICFA-PBMC (class II) positive group comparing to that in the negative group (12,217 vs 3885, p = 0.0027). ICFA-PBMC and optimized cutoff level could provide valid information in cases of suspected DSA.

Development of a humanized mouse model to analyze antibodies specific for human leukocyte antigen (HLA)

In organ transplantation, human leukocyte antigen (HLA)-mismatch grafts not only induce the activation of cellular mediated immune response but also the development of chronic antibody-mediated rejection due to the donor-specific anti-HLA antibody (DSA) produced by B cells and plasma cells interacting with the graft endothelium. Significant improvement in long-term survival after transplantation can be expected if antibody-mediated rejection due to the DSA can be overcome. However, the mechanism of producing or controlling the DSA remains to be elucidated. In recent decades, “humanized” mouse models have been widely used for the basic research of human immune systems, but a humanized mouse model to analyze the mechanism of DSA production has not been established yet. Thus, we aimed to create a humanized mouse using a severe immunodeficiency mouse (NSG mouse) administered with human peripheral blood mononuclear cells (PBMCs). Initially, we detected a very low level of human total-IgG and no anti-HLA antibodies (Abs) in these mice. In our next attempt, we mixed PBMCs of various HLA antigenic combinations with or without regulatory T cells and preconditioned them by culturing on feeder cells stably transfected with human CD40 ligand (h-CD40L) alone or with h-CD40L and human B cell activating factor (h-BAFF). They were subsequently co-cultured with the corresponding irradiated stimulator PBMCs, and all cells were administered into naïve NSG mice. Although all three humanized models had sufficient human total-IgG and anti-HLA antibody production, allospecific anti-HLA Ab production was prominently suppressed whereas non-specific anti-HLA Abs were sufficiently detected. Therefore, this novel humanized mouse model might be useful for analyzing the mechanism of anti-allogeneic human B cell tolerance induction.

The Role of Major Histocompatibility Complex in Organ Transplantation- Donor Specific Anti-Major Histocompatibility Complex Antibodies Analysis Goes to the Next Stage

Organ transplantation has progressed with the comprehension of the major histocompatibility complex (MHC). It is true that the outcome of organ transplantation largely relies on how well rejection is managed. It is no exaggeration to say that to be well acquainted with MHC is a shortcut to control rejection. In human beings, MHC is generally recognized as human leukocyte antigens (HLA). Under the current circumstances, the number of alleles is still increasing, but the function is not completely understood. Their roles in organ transplantation are of vital importance, because mismatches of HLA alleles possibly evoke both cellular and antibody-mediated rejection. Even though the control of cellular rejection has improved by recent advances of immunosuppressants, there is no doubt that antibody-mediated rejection (AMR), which is strongly correlated with donor-specific anti-HLA antibodies (DSA), brings a poor outcome. Thus, to diagnose and treat AMR correctly is a clear proposition. In this review, we would like to focus on the detection of intra-graft DSA as a recent trend. Overall, here we will review the current knowledge regarding MHC, especially with intra-graft DSA, and future perspectives: HLA epitope matching; eplet risk stratification; predicted indirectly recognizable HLA epitopes etc. in the context of organ transplantation.

Clearance of Intra-graft Donor Specific Anti-HLA Antibodies in the Early Stage of Antibody-Mediated Rejection Following Rituximab and Apheresis Therapy in Renal Transplantation

BACKGROUND

The management of acute or, in particular, chronic antibody-mediated rejection (AMR) resulting from donor-specific HLA antibodies (DSA) is a critical barrier to obtaining better long-term graft survival. To ascertain the efficacy of anti-AMR therapies, the transition of intra-graft DSA (g-DSA) was assessed.

METHODS

Allograft biopsy specimens were analyzed by graft immunocomplex capture fluorescence analysis, as previously described. One hundred recipients who underwent graft biopsies between April 2016 and December 2017 were enrolled for this study. Fifteen recipients diagnosed with g-DSA positive (+) received anti-humoral treatments and underwent follow-up biopsies. g-DSA levels were assessed again by a follow-up biopsy at 6-12 months following the treatments.

RESULTS

With anti-humoral treatments, 9 out of 15 recipients comprised a g-DSA negative (-) (3.59 ± 2.82-.58 ± .25): g-DSA6-12- group, while the remaining 6 recipients comprised a g-DSA +(20.6 ± 17.0-14.9 ± 14.1): g-DSA6-12+ group. The initial g-DSA scores were significantly higher in the g-DSA6-12+ group (P = .01). All samples were diagnosed as chronic AMR in the g-DSA+ groups, whereas there were 3 chronic AMR, 4 acute AMR, and 2 incomplete AMR samples in the g-DSA- group. Interestingly, the frequency of responsible DSA belonging to class II tended to be higher in the g-DSA6-12+ group (4/6) compared to the g-DSA6-12- group (2/9) (P = .14).

CONCLUSION

These results imply that chronic exposure to DSA causes significant and irreversible damage to the allograft. Timely and adequate anti-humoral intervention might reverse the early phase of AMR with complete clearance of g-DSA.

Graft Immunocomplex Capture Fluorescence Analysis Can Detect Intragraft Anti-Major Histocompatibility Complex Antibodies in Mice Cardiac Transplant

BACKGROUND

Immunocomplex capture fluorescence analysis has recently been applied as a method for detection of intragraft donor-specific anti-major histocompatibility complex (MHC) antibodies (DSA) in humans. Although intragraft DSA in humans is an intense topic of investigation, there is no report to assess intragraft DSA in murine organ transplantation.

METHODS

A model of presensitized mouse cardiac transplantation by donor splenocytes was used. To capture mouse MHC, anti-MHC class I/II antibodies were immobilized on Luminex beads. The MHC/DSA complexes were captured by the Luminex beads followed by detection of phycoerythrin-conjugated antimouse IgG antibodies where DSA had already reacted with the allograft in vivo.

RESULTS

Luminex beads were capable of detecting class I DSA in the cardiac allograft, though results for class II DSA were negative. Immunohistochemical investigation revealed that cardiac allografts had abundant MHC class I expression but only minor expression of MHC class II. Furthermore, MHC/class II DSA complexes were successfully detected in splenocytes and serum from a presensitized recipient.

CONCLUSIONS

These data suggested that graft immunocomplex capture fluorescence analysis can be also applied in murine cardiac transplantation. This novel application in mice would accelerate our comprehension of DSA through mechanistic studies.

Revision of the Massarineae (Pleosporales, Dothideomycetes)

We here taxonomically revise the suborder Massarineae (Pleosporales, Dothideomycetes, Ascomycota). Sequences of SSU and LSU nrDNA and the translation elongation factor 1-alpha gene (tef1) are newly obtained from 106 Massarineae taxa that are phylogenetically analysed along with published sequences of 131 taxa in this suborder retrieved from GenBank. We recognise 12 families and five unknown lineages in the Massarineae. Among the nine families previously known, the monophyletic status of the Dictyosporiaceae, Didymosphaeriaceae, Latoruaceae, Macrodiplodiopsidaceae, Massarinaceae, Morosphaeriaceae, and Trematosphaeriaceae was strongly supported with bootstrap support values above 96 %, while the clades of the Bambusicolaceae and the Lentitheciaceae are moderately supported. Two new families, Parabambusicolaceae and Sulcatisporaceae, are proposed. The Parabambusicolaceae is erected to accommodate Aquastroma and Parabambusicola genera nova, as well as two unnamed Monodictys species. The Parabambusicolaceae is characterised by depressed globose to hemispherical ascomata with or without surrounding stromatic tissue, and multi-septate, clavate to fusiform, hyaline ascospores. The Sulcatisporaceae is established for Magnicamarosporium and Sulcatispora genera nova and Neobambusicola. The Sulcatisporaceae is characterised by subglobose ascomata with a short ostiolar neck, trabeculate pseudoparaphyses, clavate asci, broadly fusiform ascospores, and ellipsoid to subglobose conidia with or without striate ornamentation. The genus Periconia and its relatives are segregated from the Massarinaceae and placed in a resurrected family, the Periconiaceae. We have summarised the morphological and ecological features, and clarified the accepted members of each family. Ten new genera, 22 new species, and seven new combinations are described and illustrated. The complete ITS sequences of nrDNA are also provided for all new taxa for use as barcode markers.

Structure, synthesis, and biological activity of a C-20 bisacetylenic alcohol from a marine sponge Callyspongia sp

An optically inactive C-20 bisacetylenic alcohol, (4E,16E)-icosa-4,16-diene-1,19-diyne-3,18-diol, was isolated from a marine sponge Callyspongia sp. as a result of screening of antilymphangiogenic agents from marine invertebrates. An optical resolution using chiral-phase HPLC gave each enantiomer, (-)-1 and (+)-2. Because the natural and synthetic enantiomers 1 and 2 showed different biological properties, we investigated the structure-activity relationships of bisacetylenic alcohols using 11 synthetic derivatives, and it is clarified that the essential structural unit for antiproliferative activity is the "1-yn-3-ol" on both termini and that there is a minimum chain length that connects the "1-yn-3-ol" moieties.

Studies on lymphangiogenesis inhibitors from Korean and Japanese crude drugs

Metastasis occurs when cancer cells detach from a tumor, travel to distant sites in the body and develop into tumors in these new locations. Most cancer patients die from metastases. Among the various forms of cancer metastasis, lymphatic metastasis is an important determinant in cancer treatment and staging. In this study, we investigated lymphangiogenesis inhibitors from crude drugs used in Japan and Korea. The three crude drugs Saussureae Radix, Psoraleae Semen and Aurantti Fructus Immaturus significantly inhibited the proliferation of temperature-sensitive rat lymphatic endothelial (TR-LE) cells in vitro. By a chromatographic method using bioassay-guided fractionation methods, costunolide (1) and dehydrocostus lactone (2) from S. Radix, p-hydroxybenzaldehyde (3), psoralen (4), angelicin (5), psoracorylifol D (6), isobavachalone (7), bavachinin (8) Δ(3),2-hydroxybakuchiol (9) and bakuchiol (10) from P. Semen and cis-octadecyl ferulate (11), (2R)-3β,7,4'-trihydroxy-5-methoxy-8-(γ,γ-dimethylallyl)-flavanone (12), (2S)-7,4'-dihydroxy-5-methoxy-8-(γ,γ-dimethylallyl)-flavanone (13) and umbelliferone (14) from A. F. Immaturus were obtained. Three compounds (compounds 11-13) from A. F. Immaturus were isolated for the first time from this medicinal plant. Among isolated compounds, ten compounds (compounds 1, 2, 6-12, 13) showed an inhibitory effect on the proliferation and the capillary-like tube formation of TR-LE cells. In addition, all compounds except compound 12 showed selective inhibition of the proliferation of TR-LE cells compared to Hela and Lewis lung carcinoma (LLC) cells. These compounds might offer clinical benefits as lymphangiogenesis inhibitors and may be good candidates for novel anti-cancer and anti-metastatic agents.

Molecular taxonomy of bambusicolous fungi: Tetraplosphaeriaceae, a new pleosporalean family with Tetraploa-like anamorphs

A new pleosporalean family Tetraplosphaeriaceae is established to accommodate five new genera; 1) Tetraplosphaeria with small ascomata and anamorphs belonging to Tetraploa s. str., 2) Triplosphaeria characterised by hemispherical ascomata with rim-like side walls and anamorphs similar to Tetraploa but with three conidial setose appendages, 3) Polyplosphaeria with large ascomata surrounded by brown hyphae and anamorphs producing globose conidia with several setose appendages, 4) Pseudotetraploa, an anamorphic genus, having obpyriform conidia with pseudosepta and four to eight setose appendages, and 5) Quadricrura, an anamorphic genus, having globose conidia with one or two long setose appendages at the apex and four to five short setose appendages at the base. Fifteen new taxa in these genera mostly collected from bamboo are described and illustrated. They are linked by their Tetraploa s. l. anamorphs. To infer phylogenetic placement in the Pleosporales, analyses based on a combined dataset of small- and large-subunit nuclear ribosomal DNA (SSU+LSU nrDNA) was carried out. Tetraplosphaeriaceae, however, is basal to the main pleosporalean clade and therefore its relationship with other existing families was not completely resolved. To evaluate the validity of each taxon and to clarify the phylogenetic relationships within this family, further analyses using sequences from ITS-5.8S nrDNA (ITS), transcription elongation factor 1-α (TEF), and β-tubulin (BT), were also conducted. Monophyly of the family and that of each genus were strongly supported by analyses based on a combined dataset of the three regions (ITS+TEF+BT). Our results also suggest that Tetraplosphaeria (anamorph: Tetraploa s. str.) is an ancestral lineage within this family. Taxonomic placement of the bambusicolous fungi in Astrosphaeriella, Kalmusia, Katumotoa, Massarina, Ophiosphaerella, Phaeosphaeria, Roussoella, Roussoellopsis, and Versicolorisporium, are also discussed based on the SSU+LSU phylogeny.

A class-wide phylogenetic assessment of Dothideomycetes

We present a comprehensive phylogeny derived from 5 genes, nucSSU, nucLSU rDNA, TEF1, RPB1 and RPB2, for 356 isolates and 41 families (six newly described in this volume) in Dothideomycetes. All currently accepted orders in the class are represented for the first time in addition to numerous previously unplaced lineages. Subclass Pleosporomycetidae is expanded to include the aquatic order Jahnulales. An ancestral reconstruction of basic nutritional modes supports numerous transitions from saprobic life histories to plant associated and lichenised modes and a transition from terrestrial to aquatic habitats are confirmed. Finally, a genomic comparison of 6 dothideomycete genomes with other fungi finds a high level of unique protein associated with the class, supporting its delineation as a separate taxon.

Intracranial penetrating injuries via the optic canal

Two cases of intracranial penetration of a plastic or wooden chopstick via the optic canal are described. CT scans showed the chopsticks as linear hypodense structures in the suprasellar cistern contiguous with the optic canal. In one case, MR imaging was performed, which clearly depicted the foreign body and adjacent brain structures. Although they are extremely rare, transorbital intracranial penetrating injuries via the optic canal require physicians' awareness.

Completely thrombosed giant fusiform aneurysm in a young patient--case report

A completely thrombosed giant fusiform aneurysm of the peripheral anterior cerebral artery occurred in a 16-year-old female, with a familial and personal history of vascular headache for 4 or 5 years. She was admitted in a drowsy state with severe headache. Computed tomography revealed subarachnoid hemorrhage and intracerebral hemorrhage as a mottled and ring-like high-density area in the left paramedian frontal lobe not enhanced postcontrast. Left carotid angiography demonstrated an avascular mass and a 5 cm defect in the A3 portion of the anterior cerebral artery. The rupture of the giant fusiform aneurysm was confirmed intraoperatively.

High-risk dural arteriovenous fistulae of the transverse and sigmoid sinuses

Dural arteriovenous fistulae of the transverse and sigmoid sinuses are highly variable in symptomatology and prognosis. However, we have identified a subgroup of patients who have a high risk of hemorrhage and dementia due to severe venous overload caused by high arterial flow into the fistulae and by occlusive changes of the transverse and sigmoid sinuses. Three representative cases selected from 31 patients with dural arteriovenous fistulae of the transverse and sigmoid sinuses are presented, and 45 reported similar cases are reviewed to discuss pathophysiology and problems encountered during treatment.

[Postoperative tension pneumocephalus--report of 3 cases]

Three cases of tension pneumocephalus are reported and pathogenesis, clinical features and management of this complication is discussed. Case 1: A 12-year-old female underwent a craniotomy for a suprasellar tumor following V-P shunting. At that time, Mayfield's pin fixing head holder was used and a CSF leak from a puncture wound caused by the head holder was noted postoperatively. Although she showed uneventful recovery from the anesthesia, several hours after surgery, she developed general convulsions and deteriorated. CT scan revealed a huge bifrontal accumulation of air compressing the entire brain postero-caudally. No active measures were taken to treat the intracranial air and a follow-up CT scan revealed a hemorrhagic infarction in the right occipital lobe possibly caused by transtentorial herniation. The patient remained in a vegetative state until her death three years later. Case 2: A 55-year-old man had a pansinectomy for sinusitis. Seven days later he developed CSF rhinorrhea and a severe headache. A CT scan revealed air in the subarachnoid space as well as in the ventricles. After repeated spinal taps, he became stuporous. An emergency repair of the CSF leak was performed. Intraoperatively, the accumulation of air was noted in the subarachnoid space under extreme tension. He made a full recovery. Case 3: A 69-year-old woman underwent a neck clipping for a ruptured anterior communicating aneurysm 2 days after the onset. Shortly before the craniotomy, a continuous spinal drainage system was installed. Postoperatively she did not recover from the anesthesia and a CT scan showed an accumulation of air in the bifrontal subdural space compressing the brain posteriorly.(ABSTRACT TRUNCATED AT 250 WORDS)