Phosphatidylserine Exposure Controls Viral Innate Immune Responses by Microglia.

Microglia are the intrinsic immune sentinels of the central nervous system. Their activation restricts tissue injury and pathogen spread, but in some settings, including viral infection, this response can contribute to cell death and disease. Identifying mechanisms that control microglial responses is therefore an important objective. Using replication-incompetent adenovirus 5 (Ad5)-based vectors as a model, we investigated the mechanisms through which microglia recognize and respond to viral uptake. Transgenic, immunohistochemical, molecular-genetic, and fluorescence imaging approaches revealed that phosphatidylserine (PtdSer) exposure on the outer leaflet of transduced cells triggers their engulfment by microglia through TAM receptor-dependent mechanisms. We show that inhibition of phospholipid scramblase 1 (PLSCR1) activity reduces intracellular calcium dysregulation, prevents PtdSer externalization, and enables months-long protection of vector-transduced, transgene-expressing cells from microglial phagocytosis. Our study identifies PLSCR1 as a potent target through which the innate immune response to viral vectors, and potentially other stimuli, may be controlled.

A structural basis for the assembly and functions of a viral polymer that inactivates multiple tumor suppressors.

Evolution of minimal DNA tumor virus' genomes has selected for small viral oncoproteins that hijack critical cellular protein interaction networks. The structural basis for the multiple and dominant functions of adenovirus oncoproteins has remained elusive. E4-ORF3 forms a nuclear polymer and simultaneously inactivates p53, PML, TRIM24, and MRE11/RAD50/NBS1 (MRN) tumor suppressors. We identify oligomerization mutants and solve the crystal structure of E4-ORF3. E4-ORF3 forms a dimer with a central ß core, and its structure is unrelated to known polymers or oncogenes. E4-ORF3 dimer units coassemble through reciprocal and nonreciprocal exchanges of their C-terminal tails. This results in linear and branched oligomer chains that further assemble in variable arrangements to form a polymer network that partitions the nuclear volume. E4-ORF3 assembly creates avidity-driven interactions with PML and an emergent MRN binding interface. This reveals an elegant structural solution whereby a small protein forms a multivalent matrix that traps disparate tumor suppressors.

Evasion of CD8+ T cells is critical for superinfection by cytomegalovirus.

Cytomegalovirus (CMV) can superinfect persistently infected hosts despite CMV-specific humoral and cellular immunity; however, how it does so remains undefined. We have demonstrated that superinfection of rhesus CMV-infected rhesus macaques (RM) requires evasion of CD8+ T cell immunity by virally encoded inhibitors of major histocompatibility complex class I (MHC-I) antigen presentation, particularly the homologs of human CMV US2, 3, 6, and 11. In contrast, MHC-I interference was dispensable for primary infection of RM, or for the establishment of a persistent secondary infection in CMV-infected RM transiently depleted of CD8+ lymphocytes. These findings demonstrate that US2-11 glycoproteins promote evasion of CD8+ T cells in vivo, thus supporting viral replication and dissemination during superinfection, a process that complicates the development of preventive CMV vaccines but that can be exploited for CMV-based vector development.

Signal peptide-dependent inhibition of MHC class I heavy chain translation by rhesus cytomegalovirus.

The US2-11 region of human and rhesus cytomegalovirus encodes a conserved family of glycoproteins that inhibit MHC-I assembly with viral peptides, thus preventing cytotoxic T cell recognition. Since HCMV lacking US2-11 is no longer able to block assembly and transport of MHC-I, we examined whether this is also observed for RhCMV lacking the corresponding region. Unexpectedly, recombinant RhCMV lacking US2-11 was still able to inhibit MHC-I expression in infected fibroblasts, suggesting the presence of an additional MHC-I evasion mechanism. Progressive deletion analysis of RhCMV-specific genomic regions revealed that MHC-I expression is fully restored upon additional deletion of rh178. The protein encoded by this RhCMV-specific open reading frame is anchored in the endoplasmic reticulum membrane. In the presence of rh178, RhCMV prevented MHC-I heavy chain (HC) expression, but did not inhibit mRNA transcription or association of HC mRNA with translating ribosomes. Proteasome inhibitors stabilized a HC degradation intermediate in the absence of rh178, but not in its presence, suggesting that rh178 prevents completion of HC translation. This interference was signal sequence-dependent since replacing the signal peptide with that of CD4 or murine HC rendered human HCs resistant to rh178. We have identified an inhibitor of antigen presentation encoded by rhesus cytomegalovirus unique in both its lack of homology to any other known protein and in its mechanism of action. By preventing signal sequence-dependent HC translocation, rh178 acts prior to US2, US3 and US11 which attack MHC-I proteins after protein synthesis is completed. Rh178 is the first viral protein known to interfere at this step of the MHC-I pathway, thus taking advantage of the conserved nature of HC leader peptides, and represents a new mechanism of translational interference.

Thrombosis of the Lap-Band system.

BACKGROUND: The laparoscopic adjustable gastric band (LAGB) has proven itself a procedure with excellent long-term weight loss results and extremely low morbidity and mortality. The LAGB has become an indispensable addition to the armamentarium of most bariatric surgeons. Commonly reported complications associated with the lap band system include gastric prolapse, band erosion, hardware infection, and port/tubing leakage. METHODS: We report a case of a patient suspected of having a Lap-Band leak. He presented with a clinical course of multiple adjustments without restriction and inability to aspirate the expected volume from the band. Following adjustment under fluoroscopy he became severely dysphagic. He underwent urgent operative exploration and was found to have an intact but overinflated band. Under close inspection, a clot in the proximal band was noted, acting as a ball valve allowing the addition of fluid but not aspiration. CONCLUSIONS: This case highlights an unusual explanation for what is thought of as typical signs of band leakage. In addition it raises serious questions about the importance of preventing blood and particulate matter from entering the Lap-Band system both at the initial operation and at subsequent adjustments.

Posterior prolapse: an important entity even in the modern age of the pars flaccida approach to lap-band placement.

BACKGROUND: The most prevalent long-term complications in patients who undergo laparoscopic adjustable gastric band (LAGB) surgery are pouch dilatation and gastric prolapse (slippage). Gastric prolapse can be divided into the anterior and posterior variety. Posterior prolapse is thought to be specific to the perigastric approach due to a lack of posterior band fixation. We report a series of 3 patients out of 1,104 who underwent LAGB placement using the pars flaccida approach and developed a posterior prolapse. METHODS: Between March 2002 and December 2005, 1,104 patients underwent LAGB insertion using the pars flaccida approach at our institution. 3 patients (0.27%) developed posterior prolapse requiring reoperation. RESULTS: All 3 patients presented with similar complaints, including solid food intolerance, gastroesophageal reflux and/or regurgitation. Although identical to those reported with anterior prolapse, diagnosis was definitively made with barium video esophagogram. All patients were treated with reoperation, but band replacement was impossible in 2 of the 3 cases secondary to extensive adhesion formation. CONCLUSION: The finding of 3 patients who experienced posterior prolapse, despite using the pars flaccida approach, highlights the fact that this complication although diminished, has not been eliminated as previously thought. We describe the presentation, work-up, and management of this rare but important entity in the modern era of LAGB.

The respiratory advantage of laparoscopic Nissen fundoplication.

BACKGROUND/PURPOSE: Laparoscopic Nissen fundoplication is replacing the open approach in the treatment of children with gastroesophageal reflux. The postoperative respiratory advantages seem obvious but remain unproven. The authors hypothesized that laparoscopic Nissen fundoplication provides postoperative respiratory advantages in neurologically normal children as well as those with mental retardation or profound neurologic impairment. METHODS: The charts of all laparoscopic Nissen fundoplications over a 4-year period were reviewed. Sixty-one laparoscopic procedures were compared with the most recent 61 consecutive open Nissen fundoplications. The following variables were reviewed: age, weight, gender, preexisting comorbidities, operating time, postoperative pulmonary complications, and length of stay. Categorical data were compared for significance utilizing chi2 cross tabulation. Variables representing numerical data were compared by t test. RESULTS: Although there appeared to be a trend toward sicker patients in the open group, the laparoscopic group showed significantly improved rates of extubation, shorter recovery room stays, shorter durations of chest physiotherapy, fewer intensive care unit admissions, more rapid resumption of baseline feedings, and overall decreased length of stay (P < 0.05). Pulmonary benefits also were noted in the neurologically impaired population when analyzed separately. CONCLUSIONS: Laparoscopic Nissen fundoplication confers a definable benefit with a significant pulmonary advantage in both neurologically normal children and those with neurologic impairment.

The telecommunication revolution in the medical field: present applications and future perspective.

In the present review, we analyze the achievements of telecommunication innovations in the medical field focusing on patient care and medical-education aspects. In this regard, the telecommunication revolution has offered medical professionals the possibility to transmit information of any sort zeroing transmission time latency and annihilating spatial distances. Although telemedicine is still in its infancy, multiple applications of this science have already been successfully tested. As an example, robotically mediated telesurgery has it made possible for surgeons to operate standing at a considerable distance from the operating table without even touching or directly seeing the surgical field. Moreover, medical education and medical consulting have acquired new and wider ranges of applicability thanks to the introduction of teleproctoring, telementoring, and teleconsulting. Finally, in the very near future, telepresence surgery will permit "virtual" operations on patients where surgeons can project their manual dexterity, psychomotor skills, and problem-solving ability to remote locations. In this context, telemedicine will support a more equal distribution of medical knowledge and promote excellence in patients' care even in the most disadvantaged environments.