The effect of negative pressure wound therapy on surgical site occurrences in closed incision abdominal wall reconstructions: a retrospective single surgeon and institution study.

PURPOSE: The use of closed incision negative pressure wound therapy (ciNPWT) in abdominal wall reconstruction is heavily debated. The current literature shows mixed results for its efficacy in preventing surgical site occurrences (SSOs), and many of the studies are limited by small sample size or a lack of generalizability. We sought to assess whether the use of prophylactic ciNPWT has an effect on reducing the rate of SSOs. METHODS: Following institutional review board approval, a retrospective analysis of a prospectively collected abdominal wall reconstruction database of a single surgeon at a single institution was completed. Two hundred and seventy patients were reviewed. Univariate and multivariate logistic regressions were performed to assess the effect of each variable on the rate of SSOs. RESULTS: Two hundred and fifty-eight patients (95.56%) met inclusion criteria. One hundred and fifty-nine (61.63%) of these patients received ciNPWT. The median duration of ciNPWT was 6 days. Multivariate logistic regression analysis showed no significant difference in the prevalence of SSOs between groups (OR = 0.843, 95% CI [0.445-1.594], p = 0.598). It did, however, show a significant decrease in the rates of seroma (7.07% vs. 0.63%, p = 0.004). Moreover, skin resection was associated with a decreased rate of SSO (OR = 0.295, 95% CI [0.096-0.911], p = 0.034). CONCLUSIONS: ciNPWT was not associated with a decrease in SSOs following abdominal wall reconstruction but did show a statistically significant decrease in postoperative seromas. Future, large prospective analyses may help further discover the utility of ciNPWT in reducing SSOs.

Investigation the relaxant effects of proton pump inhibitors and their relaxation mechanism on sheep sphincter of Oddi.

BACKGROUND: Using a relaxant agent before an endoscopic retrograde cholangiopancreatography (ERCP) might reduce complications. STUDY AIMS: We aimed to investigate the relaxant effects of proton pump inhibitors (PPIs) on sheep sphincter of Oddi (SO) and the mechanisms that might take part in this relaxant effect. PATIENTS AND METHODS: The sheep SO was mounted in an organ bath filled with Krebs-Ringer bicarbonate solution under 1.5 g tension and the relaxant effects of PPIs were evaluated in the tissues precontracted by carbachol (10-6 mol/l). The relaxant responses to the PPIs were tested in the presence of various blockers to enlighten the underlying mechanism by the PPIs. RESULTS: The PPIs exerted relaxant responses in a concentration-dependent manner in the sheep SO (P < 0.05). Esomeprazole produced the strongest relaxation. The administration of atropine, indomethacin, L-NAME, methylene blue, clotrimazole, glibenclamide, and 4-aminopyridine into the organ baths did not change the relaxations induced by PPIs in vitro (P> 0.05). On the other hand, Ca+2-activated potassium channel blocker tetraethylammonium (TEA) reduced the relaxation responses created by PPIs (P < 0.05). CONCLUSIONS: The present study suggests that PPIs create relaxation on SO partially via Ca+2-activated potassium channels. PPIs, especially esomeprazole, may be beneficial during the ERCP procedure. Further clinical studies are needed to confirm our results.

Elastostatic reversibility in thermally formed bulk metallic glasses: nanobeam diffraction fluctuation electron microscopy.

The unparalleled shaping ability of bulk metallic glasses can revolutionize commercial products having multi-length scale features with a processing time of several minutes. Despite the widespread shaping ability of these polymer-like multicomponent alloys, thermoplastic forming (TPF) can severely degrade the intrinsic properties, particularly when complex stress states are activated. The present work emphasizes the importance of elastostatic loading (ESL) which not only fully reverses deteriorated room temperature plasticity originating under TPF or post-cryostatic conditions, but also activates a rejuvenation mechanism by rendering an extended resistance against strain softening. Furthermore, the reduction in the supercooled liquid region and crystallization enthalpy measured by differential scanning calorimetry are found to be temporary, and can be fully reversed to the initial condition. HRTEM imaging of the samples are performed with an imaging spherical aberration corrector. Individual nanobeam diffraction patterns obtained by the fluctuation electron microscopy (FEM) measurements are acquired using a scanning transmission electron microscope with a probe size of 1.2 nm from a 10 × 10 raster, yielding 100 diffraction patterns. The normalized variance of a series of nanodiffraction patterns of the post-elastostatically loaded sample reveals a height decrease in the first broad peak of normalized intensity variance V(k) suggesting modifications in the medium-range structural order which in turn dramatically restores the mechanical and thermal properties. Overall, the combination of TPF and post-ESL treatment in advanced glassy metals can open a new avenue for ultra-high mechanical and thermal performance micro- and nanomechanical devices for biosensors, MOSFETs and robotics.

Hardening of shear band in metallic glass.

Strain hardening, originating from defects such as the dislocation, avails conventional metals of high engineering reliability in applications. However, the hardenability of metallic glass is a long-standing concern due to the lack of similar defects. In this work, we carefully examine the stress-strain relationship in three bulk monolithic metallic glasses. The results show that hardening is surely available in metallic glasses if the effective load-bearing area is considered instantly. The hardening is proposed to result from the remelting and ensuing solidification of the shear-band material under a hydrostatic pressure imposed by the normal stress during the shear banding event. This applied-pressure quenching densifies the metallic glass by discharging the free volume. On the other hand, as validated by molecular dynamics simulations, the pressure promotes the icosahedral short-range order. The densification and icosahedral clusters both contribute to the increase of the shear strength and therefore the hardening in metallic glasses.

Study of interactions between hyaluronan and cationic surfactants by means of calorimetry, turbidimetry, potentiometry and conductometry.

The thermodynamics of the micelle formation of the cationic surfactants tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB) with and without the addition of hyaluronan of two molecular weights was studied in aqueous solution by titration calorimetry. Macroscopic phase separation, which was detected by calorimetry and also by conductometry, occurs when charges on the surfactant and hyaluronan are balanced. In contrast, turbidimetry and potentiometry showed hyaluronan-surfactant interactions at very low surfactant concentrations. The observed differences between systems prepared with CTAB and TTAB indicate that besides the electrostatic interactions, which probably predominate, hydrophobic effects also play a significant role in hyaluronan interactions with cationic surfactants.

Effect of hypothyroidism on the purinergic responses of corpus cavernosal smooth muscle in rabbits.

AIMS: Several studies have reported evidence of hormonal abnormalities in 25-35% of impotent men. Hypothyroidism has been reported to occur in 6% of impotent men. In the present study, we examined purinergic relaxation responses in hypothyroidism in an experimental rabbit model and compared them with controls to evaluate the possible involvement of the purinergic pathway. MATERIALS AND METHODS: The study comprised 20 male New Zealand white rabbits. The rabbits were divided into two equal groups. We tested the effects of ATP, alpha beta ATP, and adenosine precontracted with phenylephrine on the isolated corpus cavernosum preparations from control and hypothyroid rabbits. We also evaluated the effects of ATP, alpha beta ATP, and adenosine on the cGMP levels in the isolated corpus cavernosum preparations from control and hypothyroid rabbits. RESULTS: T3, T4, and testosterone levels were significantly lower in hypothyroid rabbits. ATP, alpha beta ATP, carbachol, and electrical field stimulation (EFS)-induced frequency-dependent relaxation responses in the isolated rabbit corpus cavernosum strips precontracted with phenylephrine reduced significantly (P<0.05). Adenosine-induced relaxation responses did not change significantly in hypothyroid rabbits. CONCLUSION: Reduction of relaxation response in hypothyroid rabbits corpus cavernosum can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium.

The evaluation of the effects of renal failure on erectile dysfunction in a rabbit model of chronic renal failure.

OBJECTIVE: To determine whether chronic renal failure (CRF) reduces nitrergic relaxant responses in a rabbit model. MATERIALS AND METHODS: Ten rabbits underwent surgery to induce uraemia (CRF rabbits) and a further 10 a sham operation (controls). Corpus cavernosal tissue was prepared and used in organ-chamber experiments, with relaxation assessed against a background of pre-contraction with phenylephrine. At the plateau of contraction, relaxation responses to cumulative concentrations of carbachol or sodium nitroprusside (SNP), to test endothelium-dependent and -independent relaxations, respectively, were assessed. Before electrical-field stimulation (EFS), the tissue was treated with an adrenergic nerve blocker and a muscarinic receptor blocker to eliminate the adrenergic and cholinergic components, and to determine the relaxation responses to the stimulation of nonadrenergic, noncholinergic (NANC) nerves. The relaxation responses in corporal strips obtained from CRF rabbits were compared with those from controls. RESULTS: When tissues were contracted with KCl, tensions were similar in all groups. The impairment in concentration-dependent relaxation with carbachol was significant in CRF rabbits, but SNP- and papaverine-induced concentration-dependent relaxation responses were no different among the groups. EFS-induced frequency-dependent relaxations were significantly lower in CRF rabbits than in controls. CONCLUSION: CRF inhibits the NANC-mediated relaxation of rabbit corpus cavernosum smooth muscle. Changes in NANC-mediated and carbachol-induced (endothelium-dependent) relaxation of corporal smooth muscle in the rabbit are probably caused by uraemia and subsequently, hyperthyroidism, hyperparathyroidism or low testosterone levels in CRF. These results also suggest that if vasoactive agents are to be used for treating erectile dysfunction in uraemic patients, direct-acting vasodilators and phosphodiesterase inhibitors will be useful.

Effect of chronic renal failure on the purinergic responses of corpus cavernosal smooth muscle in rabbits.

OBJECTIVE: To examine purinergic relaxation responses in chronic renal failure (CRF) in an experimental rabbit model, and thus evaluate the possible involvement of the purinergic system in erectile dysfunction with CRF. MATERIALS AND METHODS: The relaxant effects of ATP were measured in strips of corpus cavernosum smooth muscle taken from control and CRF rabbits. CRF was induced in New Zealand white rabbits as previously described. Penises were excised from CRF rabbits 4 weeks after inducing uraemia. In an organ bath the strips from controls and CRF rabbit corpus cavernosum were pre-contracted with phenylephrine and increasing doses of adenosine and ATP added. RESULTS: In the pre-contracted rabbit cavernosal tissue the relaxations induced by adenosine and ATP were unchanged in CRF. CONCLUSION: The lack of any relaxant effect of adenosine or ATP on the relaxation of cavernosal smooth muscle in rabbits with CRF might be because the relaxant effects of these agents are endothelium-independent and the endothelial purinergic receptor density was unchanged in CRF.