Identification of interactions among host and bacterial proteins and evaluation of their role early during Shigella flexneri infection.

Shigella species cause diarrhoea by invading and spreading through the epithelial layer of the human colon. The infection triggers innate immune responses in the host that the bacterium combats by translocating into the host cell cytosol via a type 3 secretion system bacterial effector proteins that interfere with host processes. We previously demonstrated that interaction of the Shigella type 3 secreted effector protein IcsB with the host protein Toca-1 inhibits the innate immune response microtubule-associated protein light-chain 3 (LC3)-associated phagocytosis, and that IcsB interaction with Toca-1 is required for inhibition of this host response. Here, we show that Toca-1 in vitro precipitated not only IcsB, but also the type 3 secreted proteins OspC3, IpgD and IpaB. OspC3 and IpgD precipitation with Toca-1 was dependent on IcsB. Early during infection, most of these proteins localized near intracellular Shigella. We examined whether interactions among these proteins restrict innate host cell responses other than LC3-associated phagocytosis. In infected cells, OspC3 blocks production and secretion of the mature pro-inflammatory cytokine IL-18; however, we found that interaction of OspC3 with IcsB, either directly or indirectly via Toca-1, was not required for OspC3-mediated restriction of IL-18 production. These results indicate that interactions of the host protein Toca-1 with a subset of type 3 effector proteins contribute to the established function of some, but not all involved, effector proteins.

Continuous positive airway pressure with pressure support ventilation is effective in treating acute-onset bilateral recurrent laryngeal nerve palsy.

Acute bilateral recurrent laryngeal nerve injury leading to acute vocal cord paralysis (VCP) is a serious complication of head and neck surgery, often requiring emergent surgical intervention. Although well documented, its presentation may be sudden and unexpected, occurring despite lack of obvious intraoperative nerve injury. There is limited literature on airway management strategies for patients with acute bilateral VCP before attaining a secure airway. We report a case of acute VCP that was successfully treated with continuous positive airway pressure via facemask ventilation. This effective temporizing strategy allowed clinicians to plan and prepare for tracheostomy, minimizing potential complications.

Awake without complaints: maximizing comfort during awake fiberoptic intubation.

In obese patients with unfavorable airways, awake fiberoptic intubations are sometimes performed to maintain spontaneous respiration and airway reflexes, until a secure airway is attained. Obese patients may be sensitive to the effects of sedation. Rapid oxygen desaturation may occur as a result of brief moments of apnea from even minimal amounts of sedating medications, due to poor baseline functional reserve as well as common comorbid conditions such as obstructive sleep apnea and obesity hypoventilation syndrome. To maximize the chance of success when performing an awake fiberoptic intubation in a minimally sedated patient, the upper airway should be sufficiently anesthetized. Adequate topical anesthesia minimizes airway stimulation, optimizes patient comfort and facilitates patient compliance. We report two cases of awake fiberoptic intubation in two morbidly obese patients, where a simple apparatus, made of an atomizer embedded in an oral airway, was used to effectively topicalize the airway and achieve excellent intubating condition with minimal sedation.

Incidence, risk factors, and complications of postoperative delirium in elderly patients undergoing radical cystectomy.

OBJECTIVE: To identify the risk factors for, and complications associated with, the development of delirium after radical cystectomy. MATERIALS AND METHODS: From July 2008 to December 2009, 59 patients, aged ≥65 years and undergoing radical cystectomy, were prospectively enrolled. The baseline cognitive status was assessed using the Mini-Mental Status Examination. Postoperative delirium was assessed using the Confusion Assessment Method. RESULTS: A total of 49 patients completed the surgery and all assessments. The incidence of postoperative delirium was 29%, with duration of 1-5 days. On univariate analysis, older age and preoperative Mini-Mental Status Examination score were associated with postoperative delirium. On multivariate analysis, only age was associated with postoperative delirium (odds ratio 1.52, 95% confidence interval 1.04-2.22, P=.03). The 2 groups did not differ in pathologic stage, length of surgery, intraoperative and postoperative narcotic usage, body mass index, age-adjusted Charlson comorbidity index, activities of daily living scores, smoking history, preoperative hematocrit, estimated blood loss, urinary tract infection, interval to a regular diet, or length of hospital stay. The patients who developed postoperative delirium were more likely to undergo readmission (odds ratio 10.7, 95% confidence interval 2.2-51.8, P=.01) and reoperation (odds ratio 9.2, 95% confidence interval 1.5-55.3, P=.03) but did not differ in the 90-day and 1-year mortality rates or incidence of postoperative complications. CONCLUSION: In patients aged≥65 years, a lower preoperative Mini-Mental Status Examination score and older age were significantly associated with the development of postcystectomy delirium, as measured using the Confusion Assessment Method. The patients who developed delirium were more likely to undergo readmission and reoperation. Larger studies with multiple surgeons are needed to validate these findings.

T cell apoptosis at the maternal-fetal interface in early human pregnancy, involvement of galectin-1.

The human fetus is not rejected by the maternal immune system despite expressing paternal antigens. Natural killer cells, the major lymphocyte population of the human decidua (dNKs), express genes with immunomodulatory potential. These include galectin-1 (gal1), a lectin with apoptotic activity on activated CD8(+) T cells, Th1 and Th17 CD4(+) cells. Although many cell types at the maternal-fetal interface also produce gal1, its production by dNKs has been used here to study its function in pregnancy. Media conditioned by dNKs containing gal1 induced apoptosis of activated T cells. This effect was blocked by anti-gal1 antibodies. Decidual T (dT) cells but not peripheral T (pT) cells bound gal1 and presented a distinct glycophenotype compatible with sensitivity to gal1. Annexin V staining, TUNEL, and hypodiploidy showed a substantial proportion of apoptotic dT cells. Immunohistochemistry revealed widespread expression of gal1 as well as periglandular apoptotic dT foci that colocalized with dNKs. Thus, secretion of gal1 by dNKs and other decidual cells contributes to the generation of an immune-privileged environment at the maternal-fetal interface.

Bacterial actin assembly requires toca-1 to relieve N-wasp autoinhibition.

Actin polymerization in the mammalian cytosol can be locally activated by mechanisms that relieve the autoinhibited state of N-WASP, an initiator of actin assembly, a process that also requires the protein Toca-1. Several pathogenic bacteria, including Shigella, exploit this host feature to infect and disseminate efficiently. The Shigella outer membrane protein IcsA recruits N-WASP, which upon activation at the bacterial surface mediates localized actin polymerization. The molecular role of Toca-1 in N-WASP activation during physiological or pathological actin assembly processes in intact mammalian cells remains unclear. We show that actin tail initiation by S. flexneri requires Toca-1 for the conversion of N-WASP from a closed inactive conformation to an open active one. While N-WASP recruitment is dependent on IcsA, Toca-1 recruitment is instead mediated by S. flexneri type III secretion effectors. Thus, S. flexneri independently hijacks two nodes of the N-WASP actin assembly pathway to initiate localized actin tail assembly.