Temporal changes in Aqu/C60 physical-chemical, deposition, and transport characteristics in aqueous systems

Little is known about how temporal changes in the physical-chemical properties of C₆₀ aggregates formed in aqueous systems (termed aqu/C₆₀) can impact transport pathways contributing to ecological exposures. In this study three aqu/C₆₀ suspensions of short-term (100 days), intermediate-term (300 days), and long-term (1000 days) water exposure were first characterized for particle size distribution, water/toluene phase distribution, and surface chemistry. Then, aqu/C₆₀ deposition to a model silica surface and transport in porous media were studied by quartz crystal microbalance (QCM) and saturated sand columns. As suspension time increased, aqu/C₆₀ particle size shifted to a larger size range as determined by asymmetric flow field-flow fractionation (AF4) and the aqu/C₆₀ distribution to toluene was reduced, likely due to surface polarization as revealed by nuclear magnetic resonance (NMR) and UV-visible spectroscopy of the aqu/C₆₀ suspensions. Additionally, the deposition to silica surfaces in both QCM and column studies decreased with increased water exposure time. Although a small increase in aqu/C₆₀ aggregate size with time may partially explain the greater transport of the long-term aqu/C₆₀ because of the decreased collector efficiency for larger submicrometer particles, the polarization of the aqu/C₆₀ (thus a more hydrophilic surface) revealed by the toluene/water phase distribution and confirmed by NMR, is considered the determining factor.

Changes in agglomeration of fullerenes during ingestion and excretion in Thamnocephalus platyurus

The crustacean Thamnocephalus platyurus was exposed to aqueous suspensions of fullerenes C(60) and C(70) . Aqueous fullerene suspensions were formed by stirring C(60) and C(70) as received from a commercial vendor in deionized water (termed aqu/C(60) and aqu/C(70) ) for approximately 100 d. The Z-average (mean hydrodynamic) diameters of aqu/C(60) and aqu/C(70) aggregates as measured by dynamic light scattering were 517 ± 21 nm and 656 ± 39 nm (mean ± 95% confidence limit), respectively. Exposure of T. platyurus to fullerene suspensions resulted in the formation of dark masses in the digestive track visible under a stereo microscope (×40 magnification). Fullerene ingestion over 1 h of exposure was quantitatively determined after extraction and analysis by high-performance liquid chromatography-mass spectrometry (HPLC-MS). One-hour exposures (at 3 mg/L and 6 mg/L) resulted in aqu/C(60) burdens of 2.7 ± 0.4 µg/mg and 6.8 ± 1.5 µg/mg wet weight, respectively. Thin-section transmission electron microscopy (TEM) images of aqu/C(60) -exposed T. platyurus showed the formation in the gut of fullerene agglomerates (5-10 µm) that were an order of magnitude larger than the suspended fullerene agglomerates. Upon excretion, the observed fullerene agglomerates were in the 10- to 70-µm size range and settled to the bottom of the incubation wells. In contrast to the control polystyrene microspheres, which dispersed after depuration, the aqu/C(60) agglomerates (greater than two orders of magnitude larger than the suspended fullerenes) remained agglomerated for up to six months. When exposed to fullerenes, T. platyurus shows the potential to influence agglomerate size and may facilitate movement of these nanoparticles from the water column into sediment.

Prospective survey of secondary bleeding following anorectal surgery in a consecutive series of 1,269 patients

INTRODUCTION

As little data is available about secondary bleeding after proctological surgery, we conducted a specific survey.

PATIENTS AND METHODS

Patients operated between November 2008 and April 2009 were prospectively included. Patients were followed until last visit (day 21-28). Severity of bleeding was low (at home stay), moderate (hospitalisation for observation), or severe (transfusion, and/or homeostasis in operating room).

RESULTS

Included were 1269 patients: haemorrhoidectomy/pexy 527 (41%), fistula treatment 273 (21%), fissurectomy 197 (15%), perianal and pilonidal abscesses 124 (10%), others 148 (12%). Before surgery 78 patients were under long-term treatment with antiplatelet or anticoagulant therapy. Seventy-eight patients (6%) demonstrated 85 bleeding events. Severity rate was: low 22%, moderate 51%, and severe 27%. Ninety-five percent of events occurred before day 15. Univariate study showed increased risk after haemorrhoidopexy (P<10-3) and anticoagulant treatment (P = 0.002), decreased risk after fissurectomy and fistulotomy (P<10-3), and no relation with age, sex or operator. After multivariate study only relationship with anticoagulant treatment remained significant.

CONCLUSION

Secondary bleeding occurred in 6% of patients after proctological surgery, requiring a readmission and/or an active treatment in about 75%. Treatment with anticoagulant exposed to increased bleeding frequency.

UV irradiation and humic acid mediate aggregation of aqueous fullerene (nC₆₀) nanoparticles

The transport and fate of engineered nanomaterials is affected by multiple environmental factors, including sunlight and natural organic matter. In this study, the initial aggregation kinetics of aqueous fullerene (nC(60)) nanoparticles before and after UVA irradiation was investigated in solutions varying in ionic strength, ionic composition, and humic acid concentration. In NaCl solutions, surface oxidation induced by UV irradiation remarkably increased nC(60) stability due to the increased negative surface charge and reduced particle hydrophobicity; although humic acid greatly enhanced the stability of pristine nC(60) via the steric hindrance effect, it had little influence on the stability of UV-irradiated nC(60) in NaCl due to reduced adsorption on oxidized nC(60) surface. In contrast, UV irradiation reduced nC(60) stability in CaCl(2) due to specific interactions of Ca(2+) with the negatively charged functional groups on UV-irradiated nC(60) surface and the consequent charge neutralization. By neutralizing surface charges of both UV-irradiated nC(60) and humic acid as well as forming intermolecular bridges, Ca(2+) facilitated humic acid adsorption on UV-irradiated nC(60), resulting in enhanced stability in the presence of humic acid. These results demonstrate the critical role of nC(60) surface chemistry in its environmental transport and fate.

Fullerene C60: surface energy and interfacial interactions in aqueous systems

The underlying mechanisms of fullerene-fullerene, fullerene-water, and fullerene-soil surface interactions in aqueous systems are not well understood. To advance our understanding of these interfacial interactions, the surface properties of Buckminsterfullerene (C60) and quartz surfaces were investigated. From application of the van Oss-Chaudhury-Good model and the Young-Dupre equation, the Lifshitz-van der Waals, acid-base, and the total surface energies of C60 powder and quartz surfaces were calculated from contact angle measurements using the sessile drop technique. C60 powder measurements indicate low to medium energy surfaces of 41.7 mJ/m2 with a dominant Lifshitz-van der Waals component. In aqueous systems, hydrophobic attraction due to the high cohesion of water is the driving force for C60 aggregation. The high free energy of hydration (DeltaG(pw)(total) = -90.5 mJ/m2) indicates the high affinity of C60 particles for water. Hamaker constants of 4.02 x 10(-21) J (A(pwp)) and 2.59 x 10(-21) J (A(pws)) were derived for C60-C60 and C60-quartz interactions in aqueous systems. The results of this study indicate that surface energy is an important physical parameter that should be considered as a basic characterization property of fullerene nanomaterials.

L-arginine supplemented nondiluted blood cardioplegia: a clinical trial

AIM

L-arginine was shown to improve protection of the myocardium during coronary artery bypass graft (CABG) surgery. The objective of the present study was to determine the concentration of L-arginine to obtain the most effective protection of the myocardium during CABG surgery.

METHODS

Seventy-five patients undergoing CABG surgery were randomized in 3 groups. The first group (N.=25) was administered a placebo injection in the blood cardioplegic solution, the second group (N.=25) received an injection of 4 mmol/L of L-arginine and a third group (N.=25) an injection of 6 mmol/L of L-arginine in the blood cardioplegic solution. Blood samples from the ascending aorta and the coronary sinus catheter were collected before, immediately after and at 20 minutes after aortic cross-clamping. Total plasmatic nitrite and nitrate ratio and lactate release from the myocardium in the collected blood samples were measured.

RESULTS

Seventy-five patients averaging 62+/-7 years of age and undergoing 3.1+/-1 coronary bypass grafts during 41+/-17 minutes of aortic cross clamping time were recruited. Values of total plasmatic nitrite and nitrate ratio remains non-significant before and after aortic clamping and also between groups (P=0.9812 and 0.3573 respectively). Myocardial lactate release was statistically different before and after cross clamping (P=0.0002) and also between the 3 groups (P=0.0311).

CONCLUSION

Nondiluted blood cardioplegic solution supplemented with 4 mmol/L of L-arginine was associated with a significant decrease of myocardial lactate release after aortic cross-clamping and reperfusion during CABG surgery.

Asymmetric flow field flow fractionation of aqueous C60 nanoparticles with size determination by dynamic light scattering and quantification by liquid chromatography atmospheric pressure photo-ionization mass spectrometry

A size separation method was developed for aqueous C60 fullerene aggregates (aqu/C60) using asymmetric flow field flow fractionation (AF4) coupled to a dynamic light scattering detector in flow through mode. Surfactants, which are commonly used in AF4, were avoided as they may alter suspension characteristics. Aqu/C60 aggregates generated by sonication in deionized water ranged in size from 80 to 260 nm in hydrodynamic diameter (Dh) as determined by DLS in flow through mode, which was corroborated by analysis of fractions by DLS in batch mode and by TEM. The mass of C60 in each fraction was determined by LC-APPI-MS. Only 5.2+/-6.7% of the total aqu/C60 mass had Dh less than 80 nm, while 58+/-32% of the total aqu/C60 mass had Dh between 80 and 150 nm and 14+/-9.2% of the total aqu/C60 were between 150 and 260 nm in Dh. With the optimal fractionation parameters, 77+/-5.8% of the aqu/C60 mass eluted from the AF4 channel, indicating deposition on the AF4 membrane had occurred during fractionation; use of alternative membranes did not reduce deposition. Channel flow splitting increased detector response although channel split ratios greater than 80% of the channel flow led to decreased detector response. This is the first report on the use of AF4 for fractionating a colloidal suspension of aqu/C60.

Colloidal properties of aqueous fullerenes: isoelectric points and aggregation kinetics of C60 and C60 derivatives

Aqueous colloidal suspensions of C60 (aqu/C60) and the C60 derivatives PCBM ([6,6]-phenyl C61-butyric acid methyl ester) and the corresponding butyl and octyl esters, PCBB and PCBO (aqu/PCB-R, where R is an alkyl group), were produced by stirring in double deionized water for 5 months. Kinetically stable fullerene aggregates were formed using this procedure that ranged in intensity-averaged hydrodynamic diameter (Dh) from 193 +/- 2 nm (95% C.L.) for aqu/C60 to 259 +/- 6 nm for aqu/PCBO. Measured zeta potentials (zeta) were < -50 mV, and the isoelectric points (p) were < 1.0 for all of the aqu/fullerenes. Time-resolved dynamic light scattering (TRDLS) was used to measure aqu/fullerene Dh change with time and as a function of background solution ionic strength. The critical coagulation concentration (CCC) values for the aqu/PCB-R fullerenes were significantly higher than that of aqu/C60, indicating that the phenyl alkyl ester moieties of the equ/PCB-R fullerenes were impeding the aggregation process.

Prognosis of perioperative myocardial infarction after off-pump coronary artery bypass surgery

AIM

Perioperative myocardial infarction (PMI) is associated with long-term morbidity and mortality. CKMB cut-off level and importance of Q-wave MI have not been specifically studied after off-pump coronary artery bypass (OPCAB) surgery. The aim of this paper was to study the impact of PMI (CKMB >/= 20 times the upper normal limit [UNL] 100 mg/L) and CKMB rise (5-20 UNL) on survival and recurrent major adverse cardiac event (MACE) after OPCAB surgery.

METHODS

One thousand consecutive prospectively followed OPCAB patients operated between September 1996 and March 2004 were analyzed. Follow-up was complete in 97% of the cohort. Average follow-up was 66 +/- 28 months.

RESULTS

Overall and cardiac survival at 10 years was 70 +/- 2.6% and 88 + 2.3%, respectively. Evolving MI (EMI) occurred in 1.8%, postoperative non-Q MI (NQMI) in 1.3%, and Q-wave MI (QMI) in 2.0%. Operative mortality was higher in PMI patients (P < 0.001). After adjusting for risk factors, survivors of EMI (HR: 2.0) and QMI (HR: 2.3) but not NQMI had a lower life expectancy and a higher long-term cardiac mortality (EMI: HR: 3.5; QMI: HR: 4.3) compare to non-PMI patients. EMI and QMI were associated with a decrease MACE-free survival. CKMB 5-10 UNL did not affect overall and cardiac mortality. CKMB 10-20 UNL was associated to lower cardiac survival.

CONCLUSIONS

PMI (CKMB > 20 UNL) was a strong predictor of operative mortality. QMI and EMI were predictors of long-term mortality and cardiac morbidity after OPCAB surgery. CKMB 10-20 UNL affected long-term cardiac survival but not overall survival.

Formation of aqueous suspensions of fullerenes

Colloidal suspensions of C60, C70, and a derivative of C60, PCBM ([6,6]-Phenyl C61-butyric acid methyl ester)were produced by extended mixing in water. We examined the contribution of background solution chemistry (pH, ionic strength) on the formation of colloidal suspensions in terms of mass, aggregate size, and zeta potential. These parameters were also compared between free-settling and filtered treatments. Results indicated that all three fullerenes were highly negatively charged in aqueous systems, that it took a finite time to reach kinetically stable suspensions, and that suspension formation was pH and ionic strength dependent. With isoelectric points approaching zero, the suspensions were generally stable at pH > 3. The results indicate that it is critical to state the condition under which the formation of aqueous fullerene suspensions occurs when employing such suspensions to evaluate environmental toxicity or fate and transport of fullerenes.

Estimating diagnostic test accuracy for infectious salmon anaemia virus in Maine, USA

Infectious salmon anaemia virus (ISAV) is a pathogen of consequence to farmed Atlantic salmon, Salmo salar L. ISA control centres on active surveillance for early detection by reverse transcription polymerase chain reaction (RT-PCR), indirect fluorescent antibody assay (IFAT) and virus isolation. Because diagnostic test performance varies among populations and laboratories, the Office International des Epizooties (OIE) recommends an evaluation of test accuracy in each region of use. This is complicated in Maine, USA by the co-existence of ISAV genotypes homologous to North American (NA) and European (EU) isolates. While NA ISAV genotypes isolated in Maine are characterized by high morbidity and mortality, the single EU genotype in Maine has not yet been linked to disease or isolated by cell culture. Consequently, distinguishing among genotypes is critical to infection response. Accuracy in NA genotype detection was estimated from ISA surveillance data using latent class models. Results suggested that RT-PCR is an excellent screening test for NA ISAV genotypes in Maine, although probably with reduced specificity in the presence of EU genotypes. IFAT, in contrast, was a poor screening test for detection of ISAV in Maine, although it may be useful in confirmation of NA genotypes during disease outbreaks.

Low hemorrhoidopexy staple line does not improve results and increases risk for incontinence

BACKGROUND

The ability of stapled hemorrhoidopexy (SH) to cure hemorrhoidal symptoms appears to depend on patient characteristics and operative technique. We assessed the association between outcome of SH and patients' characteristics and procedure parameters (associated procedure, suture line height, doughnut size, presence of malpighian tissue or smooth muscle in specimen).

METHODS

A total of 68 consecutive patients (56 males) were prospectively operated by 3 different surgeons. Hemorrhoids were grade II (6%), grade III (76%) or grade IV (18%).

RESULTS

At a mean 32-week follow-up (range, 9-77), symptoms had resolved in 77% of patients, independently of any operative or clinical parameter. New onset anal incontinence occurred in 11 men (17%): all had urgency, with flatus and liquid stool incontinence in two, and flatus incontinence and mucus soiling in one. Univariate analysis revealed that persistent incontinence was associated with a staple line <6.5 mm from the dentate line, doughnut height <22 mm, and congestive external hemorrhoids; it was also operator dependent (p<0.05). At the 4-week follow-up, 19% of patients had persisting symptoms but only 8% had a demonstrable mucosal prolapse.

CONCLUSION

Although the success rate of SH may not be influenced by technical variations, risk for moderate incontinence is elevated when the stapled line is low.

Rupture de l'artère pulmonaire par cathéter de Swan-Ganz au cours de la chirurgie cardiaque : conduite à tenir et stratégie

Pulmonary artery catheterization is almost uniformly used nowadays in cardiac surgery. Although rare, rupture of the pulmonary artery following catheterization is highly lethal. This review examines ways of avoiding its occurrence and means of improving outcomes in case of rupture.

[Postoperative pain and long-term results after hemorrhoidal treatment with anopexy]

AIMS

Anopexy allows treatment of hemorrhoidal symptoms with a less painful postoperative course. This information is important for the patient, but may lead to dissatisfaction if pain level is higher than expected. To evaluate perceived pain and physical limitation levels in relation to patient's expectation. Evaluate long-term functional results.

RESULTS

Sixty-eight consecutive patients (56 males) were prospectively included. Distribution of haemorrhoid grades were 4 grade 2 (6%), 52 grade 3 (76%) and 12 grade 4 (18%). Postoperative pain level was less or equal than expected for 85% of patients, with a better acceptance superior to 45 years. Physical limitation was equally or less important than expected for 89%. At the 32 weeks follow-up hemorrhoidal symptoms were present in 23%, uninfluenced by any patient's or operative characteristics. Incontinence with urgency was reported by 17%. Presence of an alliterated continence was linked to stapled line inferior to 6,5 mm from pectineate line, doughnut height inferior to 22 mm, external hemorrhoids and related to surgeon.

CONCLUSION

Pragmatic information, although vague, about postoperative pain does not expose to patient's dissatisfaction. Functional results are not influenced by technical variation. Continence alterations are not severe, but frequent when stapled line is too close from pectineate line.

Is a good perioperative echocardiographic result predictive of durability in ischemic mitral valve repair?

BACKGROUND

Chronic ischemic mitral regurgitation is associated with poor long-term survival. Despite the increasing popularity of valve repair, its durability and long-term outcome for ischemic mitral regurgitation have recently been questioned.

METHODS

Seventy-eight patients underwent repair for ischemic mitral regurgitation between 1996 and 2002 at our institution. Of these patients, 73 had complete clinical and echocardiographic follow-up. Preoperative, intraoperative, and postoperative clinical data were obtained, and the results of echocardiograms were reviewed to assess the rate of recurrence of regurgitation after repair and to identify predictive factors.

RESULTS

The mean preoperative mitral regurgitation grade, New York Heart Association class, and left ventricular ejection fraction were 2.72, 2.65, and 39.4%, respectively. Mortality was 12.3% at 30 days and 30.1% at a mean follow-up of 39 +/- 25 months. Immediate postoperative echocardiography showed absent or mild mitral regurgitation in 89.4% of patients and showed moderate mitral regurgitation in 10.6%. Freedom from reoperation was 93.2%. Recurrent moderate mitral regurgitation (2+) was present in 36.7% of patients, and severe mitral regurgitation (3+ to 4+) was present in 20.0% at mean follow-up of 28.1 +/- 22.5 months. Only age (P = .0130) and less marked preoperative posterior tethering (P = .0362) were predictive of recurrent mitral regurgitation. Patients with a preoperative New York Heart Association class greater than II and recurrent mitral regurgitation greater than 2+ had decreased survival (P = .0152 and P = .0450, respectively).

CONCLUSIONS

Significant recurrent mitral regurgitation occurs following repair for ischemic mitral regurgitation, despite good early results. This finding raises questions about the need for improved repair techniques, better patient selection, or eventual mitral valve replacement in selected patients.

Comparison of lethal versus non-lethal sample sources for the detection of infectious salmon anemia virus (ISAV)

The emergence of infectious salmon anemia virus (ISAV) in Canada and the USA has led to the establishment of ISAV surveillance programs for cultured Atlantic salmon (Salmo salar L.) and wild fish species, including Atlantic salmon. Current testing procedures for ISAV consist of viral culture, reverse-transcription polymerase chain reaction (RT-PCR) and indirect fluorescent antibody testing (IFAT), and require lethal sampling. As the focus of this study, blood was evaluated as a possible non-lethal sample source for ISAV diagnostic screening by viral culture and RT-PCR. Tissue samples (consisting of kidney/spleen for viral culture or kidney only for RT-PCR), blood and, to a lesser extent, mucus were tested from Atlantic salmon survivors of laboratory ISAV infection trials and moribund fish from marine salmon grow-out facilities participating in a USDA-sponsored surveillance program. The trial fish represented a potential carrier population, while the surveillance fish were composed of moribund individuals from ISA clinical sites. Sample sources and diagnostic techniques were compared. Blood compared well to tissue samples for viral culture and produced a greater number of positives than did kidney samples for ISAV detection by RT-PCR. RT-PCR using both kidney and blood samples was determined to be a more sensitive assay than viral isolation. Mucus did not perform well in either assay compared to the other sample sources. Blood appears to be a reliable non-lethal sample source for the detection of ISAV by viral culture and RT-PCR in both moribund and asymptomatic fish.

Influence of diabetes and bilateral internal thoracic artery grafts on long-term outcome for multivessel coronary artery bypass grafting☆

OBJECTIVE

Diabetes mellitus is a major independent risk factor for morbidity and mortality after coronary artery bypass grafting (CABG). The aim of this study was to assess the effect of bilateral (B) internal thoracic artery grafting (ITA) in diabetic patients with multivessel CABG.

METHODS

Between 1985 and 1995, 4382 patients underwent primary isolated multivessel CABG with ITA grafting and concomitant saphenous vein grafting (SVG). Outcome of diabetic and nondiabetic patients undergoing single (S) ITA+SVG (n=419 and 2079) and BITA+SVG (n=214 and 1594) grafting was obtained at a mean follow-up of 11+/-3 years.

RESULTS

Diabetic patients were older, included more women, and had more obesity, hypertension and peripheral vascular disease than nondiabetic patients. Deep sternal wound infection rate was 1.9% for diabetic patients vs 1.2% for nondiabetic patients (P=0.2) and 30-day mortality was 1.7 vs 1.8% (P=0.9). Cox regression analysis with interaction term and propensity scoring showed that BITA grafting decreased the risk of death (Hazard Ratio=0.72 [0.57-0.91, 95%CI]) and coronary reoperation (HR=0.38 [0.19-0.77]) in both diabetic and nondiabetic patients, with no significant interaction noted. BITA grafting decreased the risk of myocardial infarction at long-term follow-up in nondiabetic patients (HR=0.72 [0.60-0.86]) but not in diabetic patients. Ten-year freedom rate from myocardial infarction in diabetic patients was 80 and 76% for SITA and BITA grafting patients, respectively. However, survival following myocardial infarction was better for patients who underwent BITA grafting, in both diabetic and nondiabetic subgroups.

CONCLUSIONS

BITA+SVG grafting in diabetic patients improves survival and decrease coronary reoperation compared with SITA+SVG at long-term follow-up. Survival following myocardial infarction is improved with BITA grafting.

[Vascular biology of coronary bypass grafts. Literature review]

Myocardial revascularisation by coronary bypass surgery is the treatment of choice for patients with multivessel disease. The most commonly used grafts are the internal mammary artery and the saphenous vein. Although the use of internal mammery artery grafts gives excellent results, venous grafts, with time, are subject to atheroma which affects their patency. Improved physiopathological understanding of the natural history of grafts, especially the saphenous vein grafts, has opened the field for different operative strategies to try and reduce the incidence of coronary graft disease. This paper reviews the literature concerning the biology of coronary grafts used for myocardial revascularisation and the current and future therapeutic implications of this data.