A comparison of tibial and peroneal venous and HePTFE bypasses in diabetics with critical limb ischemia.

OBJECTIVE: In this study we analyzed the outcome of tibial and peroneal venous and heparin-bonded expanded polytetrafluoroethylene (HePTFE) bypasses in diabetics with critical limb ischemia (CLI). We aimed to verify our hypothesis that HePTFE grafts will achieve acceptable 1-year patency and limb salvage results in patients who lack an adequate vein. METHODS: We conducted a retrospective analysis for all diabetics who underwent tibial bypass surgery in our department between October 2007 and October 2012. The study includes 97 grafts. All these patients were not suited for an endovascular therapy. We used autologous veins in 56 cases (Vein-Group) and HePTFE grafts in 41 cases (HePTFE-Group). Study endpoints were primary and secondary patency, limb salvage, and survival at 2 years postoperatively. RESULTS: Risk factors and indications were similar in both groups. The comparison between HePTFE- and Vein-Group showed significantly different patency rates. At 2 years, primary patency was 39.3% in HePTFE-Group vs. 78.5% in Vein-Group (P = .003) and secondary patency was 47.4% vs. 81.9% (P = .002). Limb salvage at 2 years was 79.3% vs. 87.4% (P = .073) and survival was 64.6% vs. 62.9% (P = .593) at the 2-year mark, with no significant differences. 30-days mortality, graft occlusion and major amputation rate showed no significant differences, either. CONCLUSIONS: This study shows that HePTFE bypasses are a viable option for diabetics undergoing tibial bypass surgery when no adequate vein is available.

Cell-sized liposome doublets reveal active tension build-up driven by acto-myosin dynamics.

Cells modulate their shape to fulfill specific functions, mediated by the cell cortex, a thin actin shell bound to the plasma membrane. Myosin motor activity, together with actin dynamics, contributes to cortical tension. Here, we examine the individual contributions of actin polymerization and myosin activity to tension increase with a non-invasive method. Cell-sized liposome doublets are covered with either a stabilized actin cortex of preformed actin filaments, or a dynamic branched actin network polymerizing at the membrane. The addition of myosin II minifilaments in both cases triggers a change in doublet shape that is unambiguously related to a tension increase. Preformed actin filaments allow us to evaluate the effect of myosin alone while, with dynamic actin cortices, we examine the synergy of actin polymerization and myosin motors in driving shape changes. Our assay paves the way for a quantification of tension changes triggered by various actin-associated proteins in a cell-sized system.

Fluctuations of a membrane nanotube revealed by high-resolution force measurements.

Pulling membrane nanotubes from liposomes presents a powerful method to gain access to membrane mechanics. Here we extend classical optical tweezers studies to infer membrane nanotube dynamics with high spatial and temporal resolution. We first validate our force measurement setup by accurately measuring the bending modulus of EPC membrane in tube pulling experiments. Then we record the position signal of a trapped bead when it is connected, or not, to a tube. We derive the fluctuation spectrum of these signals and find that the presence of a membrane nanotube induces higher fluctuations, especially at low frequencies (10-1000 Hz). We analyse these spectra by taking into account the peristaltic modes of nanotube fluctuations. This analysis provides a new experimental framework for a quantitative study of the fluctuations of nanotubular membrane structures that are present in living cells, and now classically used for in vitro biomimetic approaches.

Variance sum rule for entropy production.

Entropy production is the hallmark of nonequilibrium physics, quantifying irreversibility, dissipation, and the efficiency of energy transduction processes. Despite many efforts, its measurement at the nanoscale remains challenging. We introduce a variance sum rule (VSR) for displacement and force variances that permits us to measure the entropy production rate σ in nonequilibrium steady states. We first illustrate it for directly measurable forces, such as an active Brownian particle in an optical trap. We then apply the VSR to flickering experiments in human red blood cells. We find that σ is spatially heterogeneous with a finite correlation length, and its average value agrees with calorimetry measurements. The VSR paves the way to derive σ using force spectroscopy and time-resolved imaging in living and active matter.

Two-point phase correlations of a one-dimensional bosonic Josephson junction.

We realize a one-dimensional Josephson junction using quantum degenerate Bose gases in a tunable double well potential on an atom chip. Matter wave interferometry gives direct access to the relative phase field, which reflects the interplay of thermally driven fluctuations and phase locking due to tunneling. The thermal equilibrium state is characterized by probing the full statistical distribution function of the two-point phase correlation. Comparison to a stochastic model allows us to measure the coupling strength and temperature and hence a full characterization of the system.

Necrosis of the leg after intraarterial drug injection.

Inadvertent intraarterial injections in the context of drug abuse can cause damage to the vascular system. The clinical picture depends on the drug properties and ranges from partial ischemia to necrosis of the affected extremity. There are no current evidence-based guidelines regarding the management of intraarterial drug injections. In many cases the concept of solving vasospasm after injection is based on the use of intraarterial application of prostaglandins. We report a case in which a mixture of drugs was injected into the left femoral artery. The patient arrived 24 hours later with ischemia of the left leg at our emergency department. Angiography showed that there was no blood flowing in the leg. Despite intraarterial application of vasodilatators, regional neurolysis and thrombolyis with urokinase major amputation was unavoidable. The outcome after inadvertent injection depends on certain drug properties and the delay between injection and the beginning of therapy.

Fluctuations of a membrane nanotube covered with an actin sleeve.

Many biological functions rely on the reshaping of cell membranes, in particular into nanotubes, which are covered in vivo by dynamic actin networks. Nanotubes are subject to thermal fluctuations, but the effect of these on cell functions is unknown. Here, we form nanotubes from liposomes using an optically trapped bead adhering to the liposome membrane. From the power spectral density of this bead, we study the nanotube fluctuations in the range of membrane tensions measured in vivo. We show that an actin sleeve covering the nanotube damps its high-frequency fluctuations because of the network viscoelasticity. Our work paves the way for further studies of the effect of nanotube fluctuations on cellular functions.

Actin modulates shape and mechanics of tubular membranes.

The actin cytoskeleton shapes cells and also organizes internal membranous compartments. In particular, it interacts with membranes for intracellular transport of material in mammalian cells, yeast, or plant cells. Tubular membrane intermediates, pulled along microtubule tracks, are formed during this process and destabilize into vesicles. While the role of actin in tubule destabilization through scission is suggested, literature also provides examples of actin-mediated stabilization of membranous structures. To directly address this apparent contradiction, we mimic the geometry of tubular intermediates with preformed membrane tubes. The growth of an actin sleeve at the tube surface is monitored spatiotemporally. Depending on network cohesiveness, actin is able to entirely stabilize or locally maintain membrane tubes under pulling. On a single tube, thicker portions correlate with the presence of actin. These structures relax over several minutes and may provide enough time and curvature geometries for other proteins to act on tube stability.

Biosynthetic vascular graft: a valuable alternative to traditional replacement materials for treatment of prosthetic aortic graft infection?

BACKGROUND AND AIMS: To report the experience of a tertiary vascular surgery center using Omniflow II® biosynthetic vascular grafts for treatment of prosthetic aortic graft infection. MATERIALS AND METHODS: Retrospective analysis of all patients with prosthetic graft infections who underwent in situ aortic reconstruction using Omniflow II® grafts or other conduits between March 2015 and May 2017. Early and late mortality, perioperative complications, and reinfection rate were analyzed. RESULTS: Sixteen patients (14 males, median age 68.5, range 57-89) with prosthetic aortic graft infection were treated at our center. Eight patients received an Omniflow II® biosynthetic graft, two patients silver-triclosan coated grafts, three patients bovine pericardial tube grafts, and three patients composite bovine pericardial tube grafts with Omniflow II® graft extensions. Perioperative complications occurred in seven patients (43.8%). Early mortality rate was 18.7% (n = 3). In addition, four patients died during follow-up after a median of 11 months (range 0-34 months). We did not observe any reinfections. Bypass grafts were patent in all patients. No major limb amputations were performed during follow-up. CONCLUSION: Treatment of prosthetic aortic graft infection with Omniflow II® vascular grafts is feasible. Graft material seems to have an excellent resistance to infection and might be a valuable alternative to traditional replacement materials. Especially long-term durability has to be continuously monitored and documented.

Towards noninvasive molecular fluorescence imaging of the human brain.

Fluorescence molecular brain imaging is a new modality allowing the detection of specific contrast agents down to very low concentration ranges (picomolar) in disease models. Here we demonstrate a first noninvasive application of fluorescence imaging in the human brain, where concentrations down to about 100 nM of a nonspecific dye were detected. We argue that due to its high sensitivity, optical molecular imaging of the brain is feasible, which - together with its bedside applicability - makes it a promising technique for use in patients.

[Virtual tissue. Quaoaring]. / Virtuelles Gewebe. Quaoaring.

Virtual tissue can be generated by employing various methods. First steps en route to virtual tissue may encompass the generation of virtual cells. One such approach termed Quaoaring was applied to produce artificial erythrocytes and these were both discocyte and echinocyte in shape. The results were subsequently compared with data gleaned from scanning electron microscopy and atomic force microscopy. Quaoaring has, however, proved to be unsuccessful in creating convincing objects, particularly those which should be echinocytic in appearance.

The impact of infrainguinal endovascular interventions on the results of subsequent femoro-tibial bypass procedures: a retrospective cohort study.

BACKGROUND: Endovascular recanalization has become the accepted first-line treatment strategy for most lower extremity arterial occlusions, especially in patients with critical limb ischemia (Rutherford 4-6). Prior endovascular interventions have been described as risk factors for the outcome of subsequent lower extremity bypass surgery. The effect on subsequent tibial and peroneal bypasses is controversial. We analyzed the impact of prior endovascular lower extremity revascularization procedures on the short- and mid-term results of femoro-tibial and femoro-peroneal bypasses. METHODS: A retrospective analysis was conducted of all patients who had undergone tibial or peroneal bypass surgery after prior endovascular interventions (PEI-Group, n=40) of the same extremity in our department from October 2007 to October 2012. We compared this group with a group of patients who had received a tibial or peroneal bypass as primary revascularization procedure (BF-Group, n=93) during the same period of time because primary endovascular therapy had been deemed unfeasible in those cases. Indication in all cases was critical limb ischemia; the median age was 78 years (range 50-90 years), 45.1% were diabetics, and 42.9% were female. The graft material was autologous vein in 80 cases and HePTFE in 53 cases. Endpoints of the analysis were primary and secondary patency rates, limb salvage and survival at 2 years postoperatively. RESULTS: At 2 years overall primary patency was 68.4%, secondary patency was 69.5%, limb salvage was 83.6% and survival was 62.6%. Primary patency for the BF-Group was 74.3% vs. 55.1% for the PEI-Group (P=.310) at 2 years; secondary patency was 74.6% vs. 59.1% (P=.268). Prior endovascular intervention did not have any significant effects on limb salvage (83.7% vs. 83.6%; P=.470) or survival rates (61.0% vs. 65.0%; P=.258) at the 2-year mark, either. There were no significant differences in graft occlusion, death and major amputation rates within the first 30 postoperative days. Except for male gender, there were no significant differences in risk factors and indications between the two groups. CONCLUSIONS: Prior endovascular intervention of femoro-tibial vessels does not have a negative impact on the outcome of subsequent tibial or peroneal bypass surgery in patients with critical limb ischemia.

Histopathology and immunohistologic demonstration of the distribution of Rickettsia typhi in fatal murine typhus.

An 81-year-old woman had chills, fever, nausea, vomiting, and epigastric pain. On day 3 she had hematuria and was treated with trimethoprim-sulfamethoxazole. On day 5 she had a cough, hypotension, anemia, azotemia, and elevated hepatic enzyme levels. Her condition deteriorated with thrombocytopenia, anuria requiring dialysis, edema, and hypoalbuminemia. Treatment with chloramphenicol and doxycycline was started on day 10. By day 11, she was in hypotensive shock; on day 12 she had seizures and died. Murine typhus was diagnosed by demonstration of antibodies to Rickettsia typhi by indirect immunofluorescence. Necropsy revealed interstitial pneumonia, pulmonary edema, hyaline membranes, alveolar hemorrhages, petechiae and vasculitis in the central nervous system, interstitial myocarditis, multifocal interstitial nephritis and hemorrhages, splenomegaly, portal triaditis, and mucosal hemorrhages in urinary tract. Immunofluorescent R. typhi were demonstrated in the lungs, brain, kidneys, liver, and heart. This unusual death occurred in an elderly patient without rash who was treated too late with antirickettsial drugs.

Gadolinium-enhanced magnetic resonance imaging assessment of hydroxyapatite orbital implants.

PURPOSE: Successful prosthesis attachment depends on complete vascularization of porous coralline hydroxyapatite when it is used as an orbital implant. We retrospectively assessed the utility of gadolinium-enhanced magnetic resonance imaging to evaluate and characterize the temporal progression of this fibrovascular process, which has been histologically documented elsewhere. METHODS: Serial T1-weighted gadolinium-enhanced orbital magnetic resonance examinations were performed in five patients receiving hydroxyapatite orbital implants. Retrospective evaluation of the enhancement patterns was performed. Magnetic resonance imaging enhancement patterns guided timing of final drilling for prosthesis fixation. RESULTS: Serial gadolinium-enhanced T1-weighted sequences consistently demonstrated centrally advancing, peripheral enhancement centered on the drilled access channels. Progression over time varied, with the following two patterns demonstrated: (1) rapid peripheral enhancement, which led to diffuse enhancement (three patients); and (2) enhancement limited to the periphery, which failed to advance centrally. CONCLUSIONS: The temporal enhancement seen on magnetic resonance imaging is identical to the histologically proven fibrovascular ingrowth pattern and most likely reflects this process. Magnetic resonance imaging can identify progression of fibrovascular ingrowth into the hydroxyapatite orbital implants and guide surgical planning. It may also identify implants that fail to vascularize, thereby preventing the morbidity encountered by drilling into an avascular hydroxyapatite implant.

Shear bond strength to dentin by simulation of three-dimensional Class V cavity configuration.

The purpose of this study was to investigate the effect of composite polymerization contraction on early shear bond strength of conventional and new dentin adhesives to dentin. The dentin adhesives selected for this study, i.e., Bondlite, Gluma, Prisma Universalbond, Scotchbond LC, Scotchbond 2, and XR Bonding, were tested in combination with Silux and in combination with their respective composites. The composite was applied to the treated dentin surface in cylindrical brass moulds of 4 mm diameter and 3 mm length. The configuration of cylindrical butt-joint Class V cavities was simulated by the coating of the insides of the brass moulds with silane in order that a chemical bond to the composite could be established. The results showed that shear bond strength to dentin was higher for XR Bonding and Scotchbond 2 compared with conventional phosphate ester-based dentin adhesives and Gluma. When XR Bonding or Scotchbond 2 was used, the obstruction of polymerization contraction had no effect on the bond strength to dentin. In contrast, the dentin adhesion of Scotchbond LC/Silux, Prisma Universalbond/Prisma Microfine, Bondlite/Herculite, and Gluma/Lumifor was adversely affected by the reduction of the unbonded composite surfaces. However, this effect was not observed when Prisma Universalbond, Bondlite, and Gluma were tested in combination with Silux. It can therefore be concluded that the effect of polymerization contraction on the bond strength to dentin depends not only on the dentin adhesive but also on the type of composite used.

Leprosy in armadillos (Dasypus novemcinctus) from Texas.

Tissue sections from 237 nine-banded armadillos (Dasypus novemcinctus) from 51 central Texas counties were examined microscopically for acid-fast bacilli and/or lesions of leprosy. Neither were found. A review of the literature relative to the incidence of leprosy from armadillos in Texas indicates that residents of counties along the Texas Gulf Coast may be at risk of contracting leprosy by handling infected armadillos or their tissues.

Rocky Mountain spotted fever in Texas, 1978 through 1987.

From 1978 through 1987, there were 397 laboratory-confirmed cases of Rocky Mountain spotted fever reported in Texas. The annual number of cases ranged from 21 cases in 1986 to 108 cases in 1983. A total of 262 cases were in males. Most of the patients (52%) were 19 years of age or younger. April through August were the months of onset of symptoms for 66% of the cases. Eighty-two percent of the infected patients were hospitalized; 14 patients died. An endemic focus of Rocky Mountain spotted fever exists in north central and northeastern Texas.