ATG16L1 deficiency in macrophages drives clearance of uropathogenic E. coli in an IL-1ß-dependent manner.

Urinary tract infections (UTIs) are frequent, commonly recurrent, and costly. Deficiency in a key autophagy protein, ATG16L1, protects mice from infection with the predominant bacterial cause of UTIs, Uropathogenic E. coli (UPEC). Here, we report that loss of ATG16L1 in macrophages accounts for this protective phenotype. Compared with wild-type macrophages, macrophages deficient in ATG16L1 exhibit increased uptake of UPEC and enhanced secretion of interleukin-1ß (IL-1ß). The increased IL-1ß production is dependent upon activation of the NLRP3 inflammasome and caspase-1. IL-1ß secretion was also enhanced during UPEC infection of ATG16L1-deficient mice in vivo, and inhibition of IL-1ß signaling abrogates the ATG16L1-dependent protection from UTIs. Our results argue that ATG16L1 normally suppresses a host-protective IL-1ß response to UPEC by macrophages.

Legitimate data in remote monitoring.

An approach for ensuring legitimate data transfers of an individual within a remote healthcare solution. Biometric traits and networking are discussed for clarification of the approach. In this approach, a biometric solution is identified as a fingerprint scanner for use in a personal area network of the patient's home. Secure data exchange is acknowledged as a potential weakness in the transferring of patient data within this network. Some options are discussed to ensure security of data for the review by the caregiver. Example approaches regarding legitimacy are identified using a pulse oximeter [1], a blood pressure meter, and a weight scale as the remote patient devices in the remote healthcare solution.

Establishment of a persistent Escherichia coli reservoir during the acute phase of a bladder infection.

The vast majority of urinary tract infections are caused by strains of uropathogenic Escherichia coli that encode filamentous adhesive organelles called type 1 pili. These structures mediate both bacterial attachment to and invasion of bladder epithelial cells. However, the mechanism by which type 1 pilus-mediated bacterial invasion contributes to the pathogenesis of a urinary tract infection is unknown. Here we show that type 1-piliated uropathogens can invade the superficial epithelial cells that line the lumenal surface of the bladder and subsequently replicate, forming massive foci of intracellular E. coli termed bacterial factories. In response to infection, superficial bladder cells exfoliate and are removed with the flow of urine. To avoid clearance by exfoliation, intracellular uropathogens can reemerge and eventually establish a persistent, quiescent bacterial reservoir within the bladder mucosa that may serve as a source for recurrent acute infections. These observations suggest that urinary tract infections are more chronic and invasive than generally assumed.

Dynamic interactions between host and pathogen during acute urinary tract infections.

Urinary tract infections (UTIs) have traditionally been viewed as acute and often self-limiting infections caused predominantly by noninvasive Escherichia coli. However, this concept has been challenged by recent findings demonstrating that an acute bladder infection results from a complex series of host-pathogen interactions that can lead to bacterial invasion and persistence and that ultimately can determine the course of the infectious disease. The ability of E. coli to gain a foothold in the bladder is greatly facilitated by type 1 pilus-mediated attachment to and invasion of bladder epithelial cells. Invasion allows uropathogenic strains of E. coli to exploit the intracellular environment by replicating within these epithelial cells while evading a multitude of host defenses. An intracellular location also provides them a safe haven from many common antibiotic therapies. However, attachment and invasion also activates a cascade of innate host defenses, leading to the death and exfoliation of bladder cells and the production of inflammatory mediators. The ability of uropathogenic E. coli to flux out of cells and colonize surrounding cells provides them a mechanism to subvert these defense mechanisms and persist in the bladder epithelium for weeks following the acute infection. The persistence of E. coli in bladder tissue may be relevant to more chronic diseases of the urinary tract such as recurrent UTIs and interstitial cystitis.

Bacterial invasion augments epithelial cytokine responses to Escherichia coli through a lipopolysaccharide-dependent mechanism.

One mechanism of initiating innate host defenses against uropathogenic Escherichia coli (UPEC) is the production of cytokines by bladder epithelial cells; however, the means by which these cells recognize bacterial pathogens is poorly understood. Type 1 pili, expressed by the majority of UPEC, have been shown to have a critical role in inducing the expression of IL-6 in bladder epithelial cells after exposure to E. coli. In this study, we demonstrate that type 1 pili are not sufficient to activate IL-6 production by bladder epithelial cells. Instead, it was shown that bacterial invasion mediated by type 1 pili augments bladder epithelial responses to E. coli via an LPS-dependent mechanism, leading to the production of IL-6. RNA transcripts for the LPSR Toll-like receptor 4 (TLR4) was detected in cultured bladder epithelial cells. The in vivo role of TLR4 was assessed using C3H/HeJ mice, which express a dominant negative form of TLR4. After infection with UPEC, C3H/HeJ mice have large foci of intracellular bacteria that persist within the bladder epithelium in the absence of any notable inflammatory response. These results indicate that LPS is required for bacterial invasion to enhance host responses to E. coli within the bladder.

Bad bugs and beleaguered bladders: interplay between uropathogenic Escherichia coli and innate host defenses.

Strains of uropathogenic Escherichia coli (UPEC) are the causative agents in the vast majority of all urinary tract infections. Upon entering the urinary tract, UPEC strains face a formidable array of host defenses, including the flow of urine and a panoply of antimicrobial factors. To gain an initial foothold within the bladder, most UPEC strains encode filamentous surface adhesive organelles called type 1 pili that can mediate bacterial attachment to, and invasion of, bladder epithelial cells. Invasion provides UPEC with a protective environment in which bacteria can either replicate or persist in a quiescent state. Infection with type 1-piliated E. coli can trigger a number of host responses, including cytokine production, inflammation, and the exfoliation of infected bladder epithelial cells. Despite numerous host defenses and even antibiotic treatments that can effectively sterilize the urine, recent studies demonstrate that uropathogens can persist within the bladder tissue. These bacteria may serve as a reservoir for recurrent infections, a common problem affecting millions each year.

Type 1 pilus-mediated bacterial invasion of bladder epithelial cells.

Most strains of uropathogenic Escherichia coli (UPEC) encode filamentous adhesive organelles called type 1 pili. We have determined that the type 1 pilus adhesin, FimH, mediates not only bacterial adherence, but also invasion of human bladder epithelial cells. In contrast, adherence mediated by another pilus adhesin, PapG, did not initiate bacterial internalization. FimH-mediated invasion required localized host actin reorganization, phosphoinositide 3-kinase (PI 3-kinase) activation and host protein tyrosine phosphorylation, but not activation of Src-family tyrosine kinases. Phosphorylation of focal adhesin kinase (FAK) at Tyr397 and the formation of complexes between FAK and PI 3-kinase and between alpha-actinin and vinculin were found to correlate with type 1 pilus-mediated bacterial invasion. Inhibitors that prevented bacterial invasion also blocked the formation of these complexes. Our results demonstrate that UPEC strains are not strictly extracellular pathogens and that the type 1 pilus adhesin FimH can directly trigger host cell signaling cascades that lead to bacterial internalization.

Bacterial pili: molecular mechanisms of pathogenesis.

Gram-negative bacteria produce a diverse array of pili that mediate microbe-microbe and host-pathogen interactions important in the development of disease. The structural and functional characterization of these organelles, particularly their role in triggering signals in both the bacterium and the host upon attachment, has begun to reveal the molecular mechanisms of bacterial diseases.

Vitamin E levels in human atherosclerotic plaque: the influence of risk factors.

Recent studies suggest that vitamin E may be an important preventative factor in the development and progression of atherosclerosis. In order to more clearly define the role of vitamin E in atherosclerosis, we measured vitamin E, conjugated diens, and lipid flurochromes, as well as cholesterol, triglycerides and phospholipid in arterial and venous tissue of 83 patients. Serum cholesterol and triglyceride levels were significantly higher (P < 0.05) in patients with aortic occlusive (AIOD) and aneurysmal (AAA) disease than in control organ donors (OD). Tissue cholesterol concentrations were significantly elevated in AAA tissue when compared to OD and tissue from patients with peripheral occlusive disease (POD). Tissue from patients with AIOD contained greater concentrations of phospholipid (PL) than were measured in patients with POD and in OD. Vitamin E concentrations were highest in POD tissue and approximately 3.0, 2.0, and 1.6 fold greater than OD, AIOD and AAA tissue respectively. Diene conjugates and lipid flurochromes, measures of early and intermediate products of lipid peroxidation, were markedly elevated in all diseased arterial tissue compared to controls. There were no significant differences in tissue or serum lipid levels between saphenous vein (SVBG) and diseased vein grafts (DVG). However, conjugated diene concentrations were elevated in DVG compared to SVBG. Vitamin E levels were significantly elevated in diseased arterial and venous tissue (AIOD, AAA, POD, DVG) removed from patients with diabetes (P = 0.013) and hypertension (P = 0.049) compared to those without these risk factors. Diabetes was the only risk factor associated with significantly increased (P = 0.005) levels of vitamin E when only data from atherosclerotic arterial tissue (AAA, POD, AIOD) were analyzed. These preliminary data provide additional evidence of altered vitamin E metabolism and free radical processes in the tissues of patients with various manifestations of atherosclerosis.

Fc receptor-induced expression of Fas ligand on activated NK cells facilitates cell-mediated cytotoxicity and subsequent autocrine NK cell apoptosis.

Ligation of the Fc gamma R on NK cells by Ab-coated target cells initiates a mode of killing referred to as antibody-dependent cell-mediated cytotoxicity (ADCC). There is clear evidence that the release from NK cells of granules containing pore-forming proteins and serine proteases can result in the rapid (within minutes) cell death of Ab-coated targets. However, little information is available as to whether NK cells can initiate subsequent killing through granule-independent mechanisms and as to the mechanisms that down-regulate NK cell-mediated responses. We demonstrate in this study that FcR stimulation of activated human NK cells not only induces granule exocytosis, but also subsequently results in the transcriptional up-regulation of Fas ligand. These FcR-stimulated NK cells can then kill targets that bear Fas (CD95/APO-1), as this cytotoxicity can be inhibited by blocking Abs to the Fas receptor. In addition, as resting NK cells become activated, their Fas receptors become competent to deliver autocrine suicide signals. We demonstrate in this work that the interaction of Fas ligand on the FcR-stimulated NK cells with their Fas receptors can result in apoptosis of the NK cells. These results suggest that the FcR-induced expression of Fas ligand on activated NK cells can critically influence the capacity of these cells to mediate paracrine and autocrine cell death.

MR angiography of the foot and ankle.

To better understand the use of magnetic resonance angiography (MRA) in evaluating peripheral vascular disease, the authors studied arteries in the foot and ankle. Twenty patients with arterial occlusive disease of the lower extremity were studied with two-dimensional time-of-flight MRA, and the results were compared with those of 10 conventional x-ray arteriograms, four digital subtraction arteriograms, and three intraoperative arteriograms. The studies were reviewed and rated by three radiologists blinded to the patients' clinical history. Also, the first 16 patients were examined with MRA before and after intravenous injection of gadopentetate dimeglumine. The mean confidence levels for the reviewers' interpretations of the MRA studies were significantly higher than those for the conventional arteriograms for the medial plantar, lateral plantar, and plantar arch arteries of the feet (P < or = .005). Postcontrast MRA images were inferior to precontrast images because of overlapping of veins and arteries. Time-of-flight MRA without gadolinium can serve as a useful complementary study for evaluating patients with peripheral vascular disease in the foot and ankle.

Catheter-directed urokinase thrombolysis: an adjunct to PTA/surgery for management of lower extremity thromboembolic disease.

Catheter-directed thrombolysis was used either alone or as an adjunct to percutaneous transluminal angioplasty (PTA) or surgery for peripheral vascular occlusion on 112 occasions in 102 patients. Symptom duration ranged from < one to > twenty-eight days. Thrombolytic therapy using urokinase plasminogen activator thrombolysis (uPAT), including intrathrombic injection when possible, was successful (> 50% lysis) in 99 procedures (88%). Technical failure (< 50% lysis) occurred in 13 procedures (12%). In 9 of the 13 failures, intrathrombic injection of urokinase was not possible, but the duration of occlusion was > twenty-eight days in all but 1. Two other failures were from embolic sources and 2 more occurred in patients with a hypercoagulable state. The uPAT was adjunctive to PTA/surgery in 56 cases (50%). PTA following uPAT was required and successfully performed in 24 of 27 cases (88.9%). Surgery followed lytic therapy in another 32 (including the 3 failed PTAs). In the remaining 56 cases (50%), no additional intervention was required. There were 20 complications (18%), minor in 16 of 20 (80%). Minor complications included small puncture site hematomas and distal embolization resolved by continued lytic therapy. Four major complications occurred. One was retroperitoneal hemorrhage directly contributing to the only death in the series. The other 3 were hematuria (2) and femoral neuropathy (1). The authors conclude that catheter-directed lytic therapy alone or as an adjunct to PTA/surgery is a valuable approach to peripheral vascular thromboembolic disease. It is less likely to succeed in chronic occlusion. The incidence of complications is moderate but acceptable.

Shoelace technique for delayed primary closure of fasciotomies.

Performing a timely fasciotomy for compartment syndrome prevents ischemic injury to muscles and nerves. Fasciotomy entails incision of the overlying skin and investing fascia of the compartment, relieving pressure and enhancing tissue perfusion. Delayed primary closure is ideal, but because of skin edge retraction, the open wound must either heal secondarily or be closed with a split-thickness skin graft. The shoelace technique involves running a silastic vessel loop through skin staples placed at the skin edge along the initial fasciotomy incision. Daily tightening of the shoelace permits gradual reapproximation of the skin edges while compartment edema resolves. Closure using a simple suture or Steri-strip (3M Surgical Products, St. Paul, Minnesota) is then possible after 5 to 10 days. The shoelace technique allows for gradual primary closure of open fasciotomy wounds, thereby avoiding the morbidity and cost associated with skin graft or secondary closure.

Management of chyloperitoneum after abdominal aortic surgery.

Chyloperitoneum is a rarely reported complication of abdominal aortic surgery. From 1981 to 1992, we treated 5 cases of chylous ascites after operations on the abdominal aorta and reviewed 22 previously published cases. There were 22 men and 5 women, with a mean age of 63.8 years (range: 27 to 93 years). Twenty cases (74.7%) occurred after abdominal aortic aneurysm resection, 5 (18.5%) after aorto-femoral bypass for occlusive disease, and 2 (6.8%) after resection of infected aortic grafts, 1 for occlusive disease and the other for infrarenal aortic aneurysm. Abdominal distention was the most common presenting symptom, occurring in 26 (96.3%) of 27 patients. The mean time from aortic operation to the development of symptoms was 18.5 days (range: 7 to 120 days). Diagnosis was confirmed by paracentesis, which yielded lipemic, sterile fluid in all patients. Therapeutic paracentesis was not successful when used alone, but, when combined with a medium-chain triglyceride (MCT) diet or total parenteral nutrition (TPN), it resulted in resolution of chyloperitoneum in 8 of 14 patients (57.2%). TPN alone or with paracenteses and/or diuretics was successful in 9 of 15 (60%) patients. Peritoneovenous shunts resolved chylous ascites in four of five patients not responding to diet and/or TPN but resulted in one death due to sepsis. Operative ligation of the injured lymphatic channel was successful in all five patients treated by laparotomy when nonoperative efforts failed. Chyloperitoneum resolved in all but two (7.7%) patients. There were five (18.5%) deaths, but only three (11.5%) were directly related to chylous ascites. Treatment with TPN resolved chyloperitoneum in all five of our own patients. We reached the following conclusions: (1) Chyloperitoneum is a rare complication of aortic surgery; (2) This disorder should be considered whenever persistent abdominal distention appears after aortic surgery; (3) The diagnosis is easily confirmed by paracentesis; and (4) Surgery to close the lymph fistula should be reserved for those patients in whom conservative therapy with MCT diets or TPN has failed.