Strengthening Polylactic Acid by Salification: Surface Characterization Study

Polylactic acid (PLA) is one of the market's most commonly used biodegradable polymers, with diverse applications in additive manufacturing, specifically fused deposition modeling (FDM) 3D printing. The use of PLA in complex and sophisticated FDM applications is continually growing. However, the increased range of applications requires a better understanding of the material properties of this polymer. For example, recent studies have shown that PLA has the potential to be used in artificial heart valves. Still, the durability and longevity of this material in such a harsh environment are unknown, as heart valve failures have been attributed to salification. Additionally, there is a gap in the field for in situ material characterization of PLA surfaces during stiffening. The present study aims to benchmark different dynamic atomic force microscopy (AFM) techniques available to study the salification phenomenon of PLA at micro-scales using different PLA thin films with various salt concentrations (i.e., 10%, 15%, and 20% of sodium chloride (NaCl)). The measurements are conducted by tapping mode AFM, bimodal AFM, the force spectroscopy technique, and energy quantity analysis. These measurements showed a stiffening phenomenon occurring as the salt solution is increased, but the change was not equally sensitive to material property differences. Tapping mode AFM provided accurate topographical information, while the associated phase images were not considered reliable. On the other hand, bimodal AFM was shown to be capable of providing the topographical information and material compositional mapping through the higher eigenmode's phase channel. The dissipated power energy quantities indicated that how the polymers become less dissipative as salt concentration increases can be measured. Lastly, it was shown that force spectroscopy is the most sensitive technique in detecting the differences in properties. The comparison of these techniques can provide a helpful guideline for studying the material properties of PLA polymers at micro- and nano-scales that can prove beneficial in various fields.

Experimental Evaluation of Faecal Escherichia coli and Hepatitis E Virus as Biological Indicators of Contacts Between Domestic Pigs and Eurasian Wild Boar

Domestic pigs and Eurasian wild boar (Sus scrofa) share several important viral and bacterial pathogens. Therefore, direct and indirect contacts between domestic pigs and wild boar present a risk of pathogen spillover and can lead to long-term perpetuation of infection. Biological indicators could be a powerful tool to understand and characterize contacts between wild boar and domestic pigs. Here, faecal Escherichia coli and Hepatitis E virus (HEV) were explored as potential biological indicators under experimental conditions. The data gained in our pilot study suggest that faecal E. coli can be used as biological indicator of contact between wild boar and domestic pig. For HEV, faecal transmission was also confirmed. However, molecular studies on full-genome basis did not reveal markers that would allow tracing of transmission direction. Based on these promising results, future field studies will especially target the practicability of E. coli microbiome molecular typing as surrogate of contacts at the wildlife-livestock interface.

Continuous insulin infusion is associated with a reduced post-surgical length of stay, but not with the complication rate, in patients with diabetes mellitus undergoing coronary artery bypass graft

OBJECTIVE

To establish if glucose management with continuous intravenous insulin infusion (CII) in the early post-operative period after coronary artery bypass graft (CABG) surgery is associated with complication rate and length of hospital stay (LOS) in patients with diabetes mellitus (DM).

RESEARCH DESIGN AND METHODS

We reviewed the records of 587 patients with DM who underwent CABG from January 1999 until January 2008; 316 patients were placed on CII, while 271 patients were treated with subcutaneous insulin. We examined patient age, glycated hemoglobin (HgbA1c), 24- and 72-h post-operative average capillary blood glucose (CBG), length of stay (LOS), and the rate of complications.

RESULTS

There was no difference in HgbA1c between the groups. Mean CBG values at both 24 h and 72 h remained the same in the CII group (167 mg/dl), while in the non-CII group they were 194 mg/dl and 189 mg/dl, respectively (p<0.001 between the groups). Post-surgical median LOS was 6 days in the CII group and 6.5 days in the non-CII group (p=0.003). Complications occurred at similar rate (in 10% and 11% of patients) in the two groups.

CONCLUSIONS

CII is associated with a reduced post-surgical LOS in patients with DM who undergo CABG.

Cellular expansion and gene expression in the developing grape (Vitis vinifera L.)

Expression profiles of genes involved in cell wall metabolism and water transport were compared with changes in grape (Vitis vinifera L.) berry growth, basic chemical composition, and the shape, size, and wall thickness of cells within tissues of the berry pericarp. Expression of cell wall-modifying and aquaporin genes in berry pericarp tissues generally followed a bimodal expression profile with high levels of expression coinciding with the two periods of rapid berry growth, stages I and III, and low levels of expression corresponding to the slow-growth period, stage II. Cellular expansion was observed throughout all tissues during stage I, and only mesocarp cellular expansion was observed during stage III. Expansion of only exocarp cells was evident during transition between stages II and III. Cell wall-modifying and aquaporin gene expression profiles followed similar trends in exocarp and mesocarp tissues throughout berry development, with the exception of the up-regulation of pectin methylesterase, pectate lyase, two aquaporin genes (AQ1 and AQ2), and two expansin genes (EXP3 and EXPL) during stage II, which was delayed in the exocarp tissue compared with mesocarp tissue. Exocarp endo-(1-->3)-beta-glucanase and expansin-like gene expression was concurrent with increases in epidermal and hypodermal cell wall thickness. These results indicate a potential role of the grape berry skin in modulating grape berry growth.

[Male infertility: management strategies]

Although the objective of the urologist is to correct the factors of male infertility and to favour natural procreation, the strategy must consider also the couple and the female aspects of infertility. Some types of male infertility require specific treatment. In severe cases, recent advances in medical assistance to procreation have changed the prognosis of male infertility. Pregnancy can be obtained by the means of gamet manipulation and spermatozoid selection. Nevertheless, such techniques expose to genetic disorders transmission. Subsequently, genetic assessment is required during male infertility management, especially for difficult cases.

[Assessment of male infertility]

The diagnosis of male infertility requires methodical approach which is primarily clinical, aimed at identifying all potential factors. Biological and radiological assessments allow diagnosis confirmation, and evaluation of both prognosis and therapeutic strategy.

Size of pancreatic islets of Langerhans: a key parameter for viability after cryopreservation

Large amounts and excellent viabilities of pancreatic islets are prerequisites for recent advances in islet transplantation. Cryopreservation has been shown to enlarge transplanted cell mass, but has been accompanied by reduced viability. In this study rat pancreatic islets were differentiated into small (<200 micro m), medium (200-400 micrometers) and large (>400 micrometers) categories and their susceptibilities to different freezing conditions were evaluated: concentration of cryoprotectant (0.7-3.1 M), equilibration (15 vs. 45 min, 22 degrees C vs. on ice) and post-thaw removal of cryoprotectant (15 vs. 30 min, stepwise vs. one-step). The most prominent finding was a negative correlation between islet size and viability observed in non-frozen islets to a minor degree (r=-0.44) and significantly enhanced after cryopreservation (r<-0.8). The concentration of cryoprotectant showed the most significant influence on viability affecting small, medium and large islets. Different techniques of equilibration with the cryoprotectant resulted in significant changes of islet viability of medium islets, whereas small and large islets were unaffected. For different techniques of removal of the cryoprotectant, no significant influence on viabilities was found. We conclude that large islets represented a highly susceptible population concerning damage due to cryopreservation.

[Role of multiarray scanner in the choice of therapeutic strategy in kidney cancer. Report of a case of kidney tumor with double thrombus in inferior vena cava]

Renal cancer with caval thrombus is a disease which requires precise preoperative assessment, in order to adapt the surgical technique to the stage and extent of the disease. Recent developments in CT imaging, spiral acquisition and, more recently, the multiarray technique, allow a high quality evaluation. In the light of a case of right renal tumour with bifocal caval extension, the authors discuss the valuable contribution of this imaging modality in the staging assessment and evaluation of arterial (single or multiple artery, anatomical situation in relation to the left renal vein, presence of early bifurcations, etc.), and venous structures (renal vein, genital vein, extension of the thrombus, lumbar vein and hepatic vein). Improvements in CT imaging constitute a major progress in the staging of renal cancers with caval thrombus and make a considerable contribution to the choice of treatment strategy.

Preparative free-solution isotachophoresis for separation of human plasma lipoproteins: apolipoprotein and lipid composition of HDL subfractions

We have previously shown that plasma lipoproteins can be separated by analytical capillary isotachophoresis (ITP) according to their electrophoretic mobility in a defined buffer system. As in lipoprotein electrophoresis, HDL show the highest mobility followed by VLDL, IDL, and LDL. Chylomicrons migrate according to their net-charge between HDL and VLDL, because ITP has negligible molecular sieve effects. Three HDL subfractions were obtained which were designated fast-, intermediate-, and slow-migrating HDL. To further characterize these HDL subfractions, a newly developed free-solution ITP (FS-ITP)-system was used, that allows micro-preparative separation of human lipoproteins directly from whole plasma (Böttcher, A. et al. 1998. Electrophoresis. 19: 1110-1116). The fractions obtained by FS-ITP were analyzed for their lipid and apolipoprotein composition and by two-dimensional nondenaturing polyacrylamide gradient gel electrophoresis (2D-GGE) with subsequent immunoblotting. fHDL are characterized by the highest proportion of esterified cholesterol of all three subfractions and are relatively enriched in LpA-I. Together with iHDL they contain the majority of plasma apoA-I, while sHDL contain the majority of plasma apoA-IV, apoD, apoE, and apoJ. Pre-beta-HDL were found in separate fractions together with triglyceride-rich fractions between sHDL and LDL. In summary, ITP can separate the bulk of HDL into lipoprotein subfractions, which differ in apolipoprotein composition and electrophoretic mobility. While analytical ITP permits rapid separation and quantitation for diagnostic purposes, FS-ITP can be used to obtain these lipoprotein subfractions on a preparative scale for functional analysis. As FS-ITP is much better suited for preparative purposes than gel electrophoresis, it represents an important novel tool for the functional analysis of lipoprotein subclasses.

[Conservative surgery and iridium 192 in stage pT2 bladder tumor. A 5-year follow up]

OBJECTIVE

Study of the 5-year oncological results of a series of 24 patients treated by conservative surgery and Iridium 192 for stage pT2 bladder transitional cell carcinoma.

MATERIAL AND METHODS

Retrospective study of 24 patients (mean age: 60 years) treated between March 1979 and June 1988, for a solitary bladder tumour, with a diameter less than 5 cm, without lymphadenopathy or detectable metastases at the time of treatment. Treatment successively consisted of TUR of the lesion for histological diagnosis, preoperative pelvic irradiation of 10.5 Gy, lymph node dissection in 3 patients, insertion of brachytherapy tubes at the resection site (5 cases), associated with lumpectomy (9 cases) or partial cystectomy (10 cases). 18 patients underwent a brachytherapy with doses of 45 to 60 Gy, while 6 patients received a half-dose protocol: brachytherapy 30 Gy + postoperative external beam irradiation (20 to 30 Gy to the tumour site, 30 to 40 Gy to pelvic lymph node chains).

RESULTS

At 5 years, 2 out of 6 deaths were attributable to bladder cancer. 4 other patients died without recurrence, 4 patients relapsed at the site of brachytherapy and/or away from this site, requiring salvage cystectomy in one patient, and repeated TUR +/- BCG therapy in the other three patients. Overall, 18 out of 24 patients were alive at 5 years, 17 had a functional bladder, and 14 were free of recurrence.

CONCLUSION

Conservative surgery associated with Iridium 192 brachytherapy can be an oncologically reasonable alternative to total cystectomy for selected pT2 bladder tumours: unifocal tumours, less than 5 cm in diameter.

Strategies to Prevent and Control the Emergence and Spread of Antimicrobial-Resistant Microorganisms in Hospitals. A challenge to hospital leadership

OBJECTIVE

To provide hospital leaders with strategic goals or actions likely to have a significant impact on antimicrobial resistance, outline outcome and process measures for evaluating progress toward each goal, describe potential barriers to success, and suggest countermeasures and novel improvement strategies.

PARTICIPANTS

A multidisciplinary group of experts was drawn from the following areas: hospital epidemiology and infection control, infectious diseases (including graduate training programs), clinical practice (including nursing, surgery, internal medicine, and pediatrics), pharmacy, administration, quality improvement, appropriateness evaluation, behavior modification, practice guideline development, medical informatics, and outcomes research. Representatives from appropriate federal agencies, the Joint Commission on Accreditation of Healthcare Organizations, and the pharmaceutical industry also participated.

EVIDENCE

Published literature, guidelines, expert opinion, and practical experience regarding efforts to improve antibiotic utilization and prevent and control the emergence and dissemination of antimicrobial-resistant microorganisms in hospitals.

CONSENSUS PROCESS

Participants were divided into two quality improvement teams: one focusing on improving antimicrobial usage and the other on preventing and controlling transmission of resistant microorganisms. The teams modeled the process a hospital might use to develop and implement a strategic plan to combat antimicrobial resistance.

CONCLUSIONS

Ten strategic goals and related process and outcome measures were agreed on. The five strategic goals to optimize antimicrobial use were as follows: optimizing antimicrobial prophylaxis for operative procedures; optimizing choice and duration of empiric therapy; improving antimicrobial prescribing by educational and administrative means; monitoring and providing feedback regarding antibiotic resistance; and defining and implementing health care delivery system guidelines for important types of antimicrobial use. The five strategic goals to detect, report, and prevent transmission of antimicrobial resistant organisms were as follows: to develop a system to recognize and report trends in antimicrobial resistance within the institution; develop a system to rapidly detect and report resistant microorganisms in individual patients and ensure a rapid response by caregivers; increase adherence to basic infection control policies and procedures; incorporate the detection, prevention, and control of antimicrobial resistance into institutional strategic goals and provide the required resources; and develop a plan for identifying, transferring, discharging, and readmitting patients colonized with specific antimicrobial-resistant pathogens.