Open suture repair versus PermacolTM mesh repair of small ventral hernias in patients with end-stage kidney disease.

BACKGROUND: Ventral hernia is a common surgical problem among patients with end-stage kidney disease (ESKD), while the optimal repair technique for small ventral hernias is controversial. This study aimed to compare the outcomes of open suture repair versus biological mesh repair of small ventral hernias with defect size ≤2 cm in ESKD patients. METHOD: Data from consecutive ESKD patients who underwent elective ventral hernia repair with defect size ≤2 cm at a single institution from January 2012 to January 2022 were retrospectively reviewed. Outcomes of open suture repair were compared to PermacolTM mesh repair. The primary outcome was recurrence rate. Secondary outcomes included post-operative complications, peri-operative and post-operative dialysis regimen. RESULTS: Forty-seven ventral hernia repairs were included, with 20 being suture repairs and 27 being PermacolTM mesh repairs. Median age at hernia repair was 60 (range 32-81) years old. Pre-operatively, 42 patients (89.4%) were on peritoneal dialysis (PD). Paraumbilical hernia (59.6%) was most common. Median hernia defect size was 15 mm (range 2-20 mm). Upon median follow-up of 56 (range 9-119) months, more patients in the suture repair group developed recurrence (30% vs. 0%, p = 0.004). Median time to recurrence was 10 (range 5-16) months. There was no wound or mesh infection. The majority of patients underwent intermittent PD peri-operatively and were able to resume on PD in the long run. CONCLUSION: Ventral hernia repair is indicated in ESKD patients even for small defects; repair with PermacolTM mesh was associated with a lower recurrence rate when compared to suture repair and post-operative morbidity was low.

Long-term kidney outcomes in patients with permanent hypoparathyroidism after total thyroidectomy for benign disease: A population-based study.

BACKGROUND: Permanent hypoparathyroidism is a significant complication after total thyroidectomy. This study aimed to evaluate the long-term impact of postoperative permanent hypoparathyroidism on kidney outcomes. METHODS: Data of patients undergoing total thyroidectomy from 1999 to 2014 were retrieved. The estimated glomerular filtration rate was determined from serum creatinine results. Permanent hypoparathyroidism was defined as requiring oral calcium and vitamin D supplements postoperatively for at least 6 months. The primary outcome was a sustained decline in the estimated glomerular filtration rate from baseline by ≥50%. Secondary outcomes were end-stage kidney disease (a composite of sustained estimated glomerular filtration rate <15 mL/min/1.73 m2, need for dialysis, and kidney transplantation) and rate of estimated glomerular filtration rate decline. Patients with and without permanent hypoparathyroidism were compared. Multivariable Cox regression analysis was performed to identify independent risk factors for sustained estimated glomerular filtration rate decline by ≥50%. RESULTS: In total, 3,245 patients were eligible for analysis; 418 patients (12.9%) had permanent hypoparathyroidism. Upon median follow-up of 11.6 years, more patients with permanent hypoparathyroidism had a sustained decline in estimated glomerular filtration rate from baseline by ≥50% compared to those without (15.6% vs 6.9%, P < .001). Similar findings were obtained on Kaplan-Meier analysis (P < .001). Permanent hypoparathyroidism was an independent risk factor for sustained estimated glomerular filtration rate decline by ≥50% (adjusted hazard ratio 2.77, P < .001). Other risk factors included age, preoperative estimated glomerular filtration rate <60 mL/min/1.73m2, and diabetes mellitus. Patients with permanent hypoparathyroidism had a more rapid estimated glomerular filtration rate decline (-1.60 vs -0.70 mL/min/1.73 m2/year, difference -0.91 mL/min/1.73m2/year, P < .001). CONCLUSION: Patients with postsurgical permanent hypoparathyroidism were at greater risk of renal impairment. Further research is warranted to improve the identification and preservation of parathyroid glands during thyroidectomy to minimize patient morbidity.

The Two-Year Results of Using Radiofrequency Ablation as a Novel Treatment for Persistent or Relapsed Graves' Disease: A Prospective Study.

Objectives: Graves' disease (GD) is the most common cause of hyperthyroidism. Antithyroid drugs (ATDs) are the first-line treatment, but when discontinued, >50% of patients experience relapses. Conventional definitive treatment options include surgery and radioiodine therapy (RAI), each with its own disadvantages. Radiofrequency ablation (RFA) achieved promising short-term remission rates in a previous pilot study. The current study reports our experience of using RFA to treat relapsed GD in the largest cohort of patients with a longer follow-up period. Methods: This single-arm prospective study recruited consecutive patients aged ≥18 with persistent/relapsed GD requiring ATD from two tertiary endocrine surgery centers. Those with compressive goiter, suspected thyroid malignancy, moderate-to-severe Graves' ophthalmopathy, preference for surgery/RAI, or pregnancy were excluded. Eligible patients received ultrasound-guided RFA to the entire bulk of the thyroid gland. ATDs were discontinued afterward, and thyroid function tests were monitored bimonthly. The primary outcome was the disease remission rate at 24 months follow-up after single-session RFA, defined as being biochemically euthyroid or hypothyroid without ATD. Secondary outcomes were complication rates. Results: Of the 100 patients considered, 30 (30.0%) patients were eligible and received RFA. Most were female patients (93.3%). The median total thyroid volume was 23 mL (15.9-34.5). All completed 24 months follow-up. After single-session RFA, disease remission rates were 60.0% at 12 months and 56.7% at 24 months. Among the 13 patients with relapse after RFA, 9 (69%) required a lower ATD dose than before RFA; 2 received surgery without complications. Total thyroid volume was the only significant factor associated with relapse after RFA (odds ratio 1.054, confidence interval 1.012-1.099, p = 0.012). At 24 months, RFA led to disease remission in 100% of the 9 patients with a total thyroid volume <20 mL and 35% of patients with a total thyroid volume ≥20 mL (p = 0.007). There was no vocal cord palsy, skin burn, hematoma, or thyroid storm after RFA. Conclusions: In a highly selected group of patients with relapsed GD and predominantly small thyroid glands, single-session RFA may achieve disease remission. Smaller total thyroid volume may be a favorable factor associated with disease remission after RFA. The results of this study need to be confirmed with a long-term clinical trial. Clinical Trial Registration: This study is registered at www.clinicaltrial.gov with identifier NCT06418919.

Defining the surgical management for non-colorectal liver metastases.

BACKGROUND: Surgical resection is indicated for resectable colorectal liver metastases (CLM), but it is controversial for non-colorectal liver metastases (NCLM). This study aimed to compare survival outcomes of patients with resection of NCLM versus CLM and to identify prognostic factors for resection of NCLM. METHODS: Consecutive patients who underwent surgical resection of liver metastases at Queen Mary Hospital, Hong Kong from January 1989 to December 2019 were retrospectively reviewed. Patients with resected NCLM were compared to those with CLM. Overall and recurrence-free survival were determined. Subgroup analyses with patients grouped according to the year of liver resection, from 1989 to 2004 and from 2005 to 2019, were conducted. Univariate and multivariate analyses were performed to identify prognostic factors. RESULTS: Among 674 patients included, 151 (22.4%) had NCLM while 523 (77.6%) had CLM. There were no statistically significant differences in median overall survival (65.2 vs 43.6 months, p = 0.555) and recurrence-free survival (12.5 vs 11.7 months, p = 0.425). The 1-year, 3-year, 5-year and 10-year overall survival rates were 89.8% vs 91.5%, 59.4% vs 58.8%, 50.6% vs 38.7% and 34.1% vs 26.3% in NCLM and CLM groups, respectively. Subgroup analyses demonstrated no statistically significant difference in overall survival between resection of NCLM versus CLM in both time intervals. In the NCLM group, better overall survival was found in liver metastasis of gastrointestinal stromal tumour (GIST) origin (hazard ratio (HR) 0.138, p = 0.003) and with a longer time interval from resection of primary tumour to resection of NCLM (HR 0.982, p = 0.042). Poor prognostic factors were presence of blood transfusion (HR 5.588, p = 0.013) and post-operative complications of Clavien-Dindo Grade IIIa or above (HR 74.853, p = 0.003). CONCLUSIONS: Surgical resection of NCLM had comparable survival outcomes with CLM. With appropriate patient selection, the indication of liver resection could be expanded to NCLM.

Chimeric Ligands of Pili and Lectin A Inhibit Tolerance, Persistence, and Virulence Factors of Pseudomonas aeruginosa over a Wide Range of Phenotypes.

Bacteria readily form resilient phenotypes to counter environmental and antibiotic stresses. Here, we demonstrate a class of small molecules that inhibit a wide range of Pseudomonas aeruginosa phenotypes and enable antibiotics to kill previously tolerant bacteria, preventing the transition of tolerant bacteria into a persistent population. We identified two proteins, type IV pili and lectin LecA, as receptors for our molecules by methods including a new label-free assay based on bacterial motility sensing the chemicals in the environment, the chemical inhibition of bacteriophage adsorption on pili appendages of bacteria, and fluorescence polarization. Structure-activity relationship studies reveal a molecule that inhibits only pili appendage and a class of chimeric ligands that inhibit both LecA and pili. Important structural elements of the ligand are identified for each protein. This selective ligand binding identifies the phenotypes each protein receptor controls. Inhibiting LecA results in reducing biofilm formation, eliminating small colony variants, and is correlated with killing previously tolerant bacteria. Inhibiting pili appendages impedes swarming and twitching motilities and pyocyanin and elastase production. Because these phenotypes are controlled by a broad range of signaling pathways, this approach simultaneously controls the multiple signaling mechanisms preventing bacteria to elude antibiotic treatments.

Chemical control over Asialo-GM1: A dual ligand for pili and Lectin A that activates swarming motility and facilitates adherence of Pseudomonas aeruginosa.

Glycolipid, ganglio-N-tetraosylceramide (asialo-GM1), on the mammalian cells are known to be recognized by type IV pili of Pseudomonas aeruginosa. In this work, we show that asialo-GM1 can also be recognized by Lectin A (LecA), another adhesin protein of the P. aeruginosa, by a fluorescent polarization assay, a label-free bacterial motility enabled binding assay, and bacterial mutant studies. On hydrated semi-solid gel surfaces, asialo-GM1 enables swarming and twitching motilities, while on solid surfaces facilitates the bacterial adherence of P. aeruginosa. These results indicate that asialo-GM1 can modulate bioactivities, adherence, and motilities, that are controlled by opposite signaling pathways. We demonstrate that when a solution of pilin monomers or LecA proteins are spread on hydrated gel surfaces, the asialo-GM1 mediated swarming motility is inhibited. Treatment of artificial liposomes containing asialo-GM1 as a component of lipid bilayer with pilin monomers or LecA proteins caused transient leakage of encapsulated dye from liposomes. These results suggest that pili and LecA proteins not only bind to asialo-GM1 but can also cause asialo-GM1 mediated leakage. We also show that both pili and LecA mutants of P. aeruginosa adhere to asialo-GM1 coated solid surfaces, and that a class of synthetic ligands for pili and LecA inhibits both pili and LecA-mediated adherence of P. aeruginosa on asialo-GM1-coated surfaces.

Eltrombopag as frontline treatment of aplastic anaemia in routine practice: implications on cost and efficacy.

The thrombopoietin mimetic eltrombopag (EPAG) is efficacious in clinical trials of newly diagnosed moderate (M), severe (S) and very severe (vS) aplastic anaemia (AA). Its use in routine practice and resource-constrained settings is not well described. Twenty-five men and 38 women at a median age of 54 (18-86) years with newly diagnosed AA treated consecutively in a 7-year period with EPAG (N = 6), EPAG/cyclosporine (CsA) (N = 33) and EPAG/CsA/anti-thymocyte globulin (ATG) (N = 24) were analyzed. Because EPAG was not reimbursed, peak doses ranged from 25 to 200 mg/day depending on affordability. EPAG/CsA-treated patients were older (median age: 61 years) with less severe AA (MAA, N = 15; SAA, N = 14; vSAA, N = 4), whereas EPAG/CsA/ATG-treated patients were younger (median age: 44 years) with more severe AA (MAA, N = 2; SAA, N = 12, vSAA, N = 10). The overall/trilineage response rates were 83%/50% for EPAG-treated patients; 79%/42% for EPAG/CsA-treated patients and 75%/63% for EPAG/CsA/ATG-treated patients. Adverse events included grade 1 liver derangement (N = 7) and grade 1 dyspepsia (N = 3). The 5-year overall survivals/failure-free survivals were 62%/80% for the entire cohort; 55%/75% for EPAG/CsA-treated patients and 82%/78% for EPAG/CsA/ATG-treated patients. EPAG showed robust efficacy in AA in routine practice. However, EPAG dosage and combinations remain to be optimized for AA of different severities.

Exploration of Ligand-receptor Binding and Mechanisms for Alginate Reduction and Phenotype Reversion by Mucoid Pseudomonas aeruginosa.

Bacteria in general can develop a wide range of phenotypes under different conditions and external stresses. The phenotypes that reside in biofilms, overproduce exopolymers, and show increased motility often exhibit drug tolerance and drug persistence. In this work, we describe a class of small molecules that delay and inhibit the overproduction of alginate by a non-swarming mucoid Pseudomonas aeruginosa. Among these molecules, selected benzophenone-derived alkyl disaccharides cause the mucoid bacteria to swarm on hydrated soft agar gel and revert the mucoid to a nonmucoid phenotype. The sessile (biofilm) and motile (swarming) phenotypes are controlled by opposing signaling pathways with high and low intracellular levels of bis-(3',5')-cyclic diguanosine monophosphate (cdG), respectively. As our molecules control several of these phenotypes, we explored a protein receptor, pilin of the pili appendages, that is consistent with controlling these bioactivities and signaling pathways. To test this binding hypothesis, we developed a bacterial motility-enabled binding assay that uses the interfacial properties of hydrated gels and bacterial motility to conduct label-free ligand-receptor binding studies. The structure-activity correlation and receptor identification reveal a plausible mechanism for reverting mucoid to nonmucoid phenotypes by binding pili appendages with ligands capable of sequestering and neutralizing reactive oxygen species.

Laparoscopic Total Extraperitoneal Groin Hernia Repair in Females: Comparison of Outcomes Between Preservation or Division of the Uterine Round Ligament.

Background: Laparoscopic repair has been recommended as the method-of-choice of groin hernia repair among women. Whether the round ligament of uterus should be divided to facilitate mesh placement remains controversial. This study aims to review the outcomes of laparoscopic total extraperitoneal (TEP) groin hernia repair in women and to evaluate the impact of division of round ligament. Methods: Consecutive female patients with inguinal or femoral hernias who underwent elective laparoscopic TEP repair at a single institution from 2006 to 2017 were included for retrospective analysis. Primary outcomes were postoperative pain, genital prolapse, and recurrence. Outcomes of patients who had the round ligament divided were further compared with those with round ligament preserved and multivariable adjusted analysis was performed. Results: Sixty-eight patients with a total of 77 TEP repairs were included in the 12-year study period. The mean age was 45 ± 16 years old. Incidental femoral hernia was identified in 4 patients (5.9%). There was 1 (1.3%) recurrence upon mean follow-up of 42.9 ± 37.3 months. The round ligament was divided in 67.5% of patients, and upon multivariable adjusted analysis, there were no statistically significant differences in outcomes in terms of chronic pain (odds ratio [OR] = 2.210, P = .357), paresthesia (OR = 0.241, P = .149), and genital prolapse (OR = 0.327, P = .415) when compared with patients with preserved round ligament. Conclusion: Laparoscopic groin hernia repair in women is associated with low recurrence. Division of round ligament intraoperatively facilitates mesh placement and has minimal impact on clinical outcomes.

Evaluation of Pancreatic Lesions With Endoscopic Ultrasound and Fine Needle Aspiration.

Background. Endoscopic ultrasound (EUS) and fine-needle aspiration (FNA) are commonly used for assessing pancreatic lesions. This study aimed to evaluate the diagnostic yield and accuracy of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in a single tertiary institution. Methods. Consecutive patients who underwent EUS-FNA of the pancreas at Queen Mary Hospital, Hong Kong, from January 2015 to March 2016 were retrospectively reviewed. Endoscopic findings and FNA results were analysed. For patients who subsequently underwent surgical resection of pancreatic lesion, EUS-FNA diagnoses were compared to histopathological findings of surgical specimens to determine its diagnostic accuracy. Results. One hundred twelve EUS-FNA were performed in 99 patients within the study time period and were included for analysis. Sixty-six (66.7%) pancreatic lesions were solid in nature and 33 (33.3%) were cystic. The overall diagnostic yield of EUS-FNA was 70.5% (n = 79). On multivariate analysis, more passes of needle were associated with a higher diagnostic yield (odds ratio = 2.000, P = .049). 57.1% (n = 64) of EUS-FNA results had an impact on management. Sixteen patients with diagnostic EUS-FNA subsequently underwent surgery for resection of the pancreatic lesion. Upon correlation to the histopathological findings of surgical specimens, there were 12 true-positive, 2 true-negative, 0 false-positive, and 2 false-negative cases. Sensitivity was 85.7%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 50%. The diagnostic accuracy of EUS-FNA was 87.5%. Conclusion. EUS-FNA is accurate and reliable for diagnosing pancreatic lesions.

Tension-free mesh repair of inguinal hernia in patients on continuous ambulatory peritoneal dialysis.

BACKGROUND: Peritoneal dialysis (PD) is the first-line renal replacement therapy for end-stage renal failure patients in Hong Kong. Abdominal wall hernia is a common mechanical complication of PD, and early surgical repair has been advocated to reduce complications. This study aims to review the outcomes of tension-free mesh repair of inguinal hernia in PD patients. METHODS: All PD patients who underwent elective repair of inguinal hernia from 2009 to 2015 were identified from a single centre for retrospective analysis. Primary outcomes included surgical complications, perioperative dialysis technique and recurrence. RESULTS: Twenty-one patients with a total of 26 inguinal hernia repairs were included in this 7-year retrospective study. All were males, and the mean age was 68 ± 10 years. Diabetic nephropathy (n = 9, 42.9%) and glomerulonephritis (n = 7, 33.3%) were the two most common causes of renal failure. All hernias were detected after the initiation of PD, and the mean duration of PD to hernia detection was 16 months (range 1-65 months). Lichtenstein open mesh repair was performed in all patients. Complications included seroma (n = 3, 11.5%) and ischaemic orchitis (n = 1, 3.8%). There were no mesh infection or recurrence. Twenty patients (95.2%) received intermittent peritoneal dialysis post-operatively and returned to continuous ambulatory PD in 15 to 30 days. Only one patient (4.8%) required bridging haemodialysis due to Tenckhoff catheter blockage. CONCLUSIONS: Tension-free mesh repair is associated with low morbidity and low recurrence rates in PD patients. Timely management and close collaboration with renal physicians are essential to continue PD after repair.

Cell-Wall-Targeting Antibiotics Cause Lag-Phase Bacteria to Form Surface-Mediated Filaments Promoting the Formation of Biofilms and Aggregates.

Antibiotics are known to promote bacterial formation of enhanced biofilms, the mechanism of which is not well understood. Here, using biolayer interferometry, we have shown that bacterial cultures containing antibiotics that target cell walls cause biomass deposition on surfaces over time with a linear profile rather than the Langmuir-like profiles exhibited by bacterial adherence in the absence of antibiotics. We observed about three times the initial rate and 12 times the final biomass deposition on surfaces for cultures containing carbenicillin than without. Unexpectedly, in the presence of antibiotics, the rate of biomass deposition inversely correlated with bacterial densities from different stages of a culture. Detailed studies revealed that carbenicillin caused faster growth of filaments that were seeded on surfaces from young bacteria (from lag phase) than those from high-density fast-growing bacteria, with rates of filament elongation of about 0.58 and 0.13 µm min-1 , respectively. With surfaces that do not support bacterial adherence, few filaments were observed even in solution. These filaments aggregated in solution and formed increased amounts of biofilms on surfaces. These results reveal the lifestyle of antibiotic-induced filamentous bacteria, as well as one way in which the antibiotics promote biofilm formation.

Transcarotid Artery Revascularization as a New Modality of Treatment for Carotid Stenosis.

BACKGROUND: Carotid artery stenosis is a significant cause of ischemic stroke, and studies have shown that transfemoral carotid artery stenting is associated with a higher perioperative stroke risk than open endarterectomy. Transcarotid artery revascularization (TCAR) is a novel technique in carotid stenting via direct transcervical carotid access without the risk of arch manipulation, offers a smaller wound compared with endarterectomy, and employs flow reversal to decrease the risk of antegrade embolic stroke. Contemporary evidence on the safety and efficacy of TCAR is reviewed. METHODS: A systematic literature review on TCAR from January 2009 to August 2019 was performed in PubMed and EMBASE databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. Clinical studies on TCAR with flow reversal with clinical outcomes of stroke, myocardial infarction (MI), and death were included. RESULTS: Initial search of the literature yielded 161 articles, of which 8 studies were included comprising of 5 single-arm studies and 3 comparative studies. Studies demonstrated high technical success rates of TCAR from 90.6% to 100%, with low perioperative stroke, MI, and mortality rates of 0 to 4%, 0 to 0.7% and 0 to 2.7%, respectively. TCAR was significantly associated with a lower in-hospital stroke/transient ischemic attack rate when compared to transfemoral carotid stenting. There was no significant difference in perioperative stroke/MI/death when compared to endarterectomy although TCAR had a significantly lower risk of cranial nerve injury. CONCLUSIONS: TCAR with flow reversal is a promising treatment option for carotid occlusive disease. Clinical trials are currently underway to provide a better report on outcomes of TCAR and for further comparison between TCAR and carotid endarterectomy.

Cromoglycate mesogen forms isodesmic assemblies promoted by peptides and induces aggregation of a range of proteins.

Disodium cromoglycate (5'DSCG) belongs to a class of nonamphiphilic molecules that form nematic chromonic liquid crystals in aqueous solutions. As the concentration increases, it is believed that the molecules first form isodesmic assemblies in water, which further align to form liquid crystal phases. However, the reports on isodesmic assemblies of 5'DSCG have been scarce. Herein, we show that the presence of peptides can promote the isodesmic assembly of 5'DSCG over a broad range of concentrations before reaching the liquid crystal phase. The presence of peptides can lower the 5'DSCG concentration in the aqueous solution to ∼1.5 wt% (from 11-12 wt%, forming a nematic liquid crystal phase) for isodesmic assembly formation. This result indicates a demixing between 5'DSCG and peptides in aqueous solution. We further explored this demixing mechanism to precipitate a wide range of proteins, namely, lectin A, esterase, lipase, bovine serum albumin, trypsin, and a pilin protein from bacterium Pseudomonas aeruginosa. We found that 5'DSCG caused the aggregation of all these proteins except trypsin. These results, along with past findings, suggest that 5'DSCG isodesmic assemblies have the potential to assist in protein purification and crystallization.

Polymertropism of rod-shaped bacteria: movement along aligned polysaccharide fibers.

In nature, bacteria often live in surface-associated communities known as biofilms. Biofilm-forming bacteria typically deposit a layer of polysaccharide on the surfaces they inhabit; hence, polysaccharide is their immediate environment on many surfaces. In this study, we examined how the physical characteristics of polysaccharide substrates influence the behavior of the biofilm-forming bacterium Myxococcus xanthus. M. xanthus responds to the compression-induced deformation of polysaccharide substrates by preferentially spreading across the surface perpendicular to the axis of compression. Our results suggest that M. xanthus is not responding to the water that accumulates on the surface of the polysaccharide substrate after compression or to compression-induced changes in surface topography such as the formation of troughs. These directed surface movements do, however, consistently match the orientation of the long axes of aligned and tightly packed polysaccharide fibers in compressed substrates, as indicated by behavioral, birefringence and small angle X-ray scattering analyses. Therefore, we suggest that the directed movements are a response to the physical arrangement of the polymers in the substrate and refer to the directed movements as polymertropism. This behavior might be a common property of bacteria, as many biofilm-forming bacteria that are rod-shaped and motile on soft surfaces exhibit polymertropism.

Synthetic analogs of rhamnolipids modulate structured biofilms formed by rhamnolipid-nonproducing mutant of Pseudomonas aeruginosa.

Rhamnolipids secreted by Pseudomonas aeruginosa are required for the bacteria to form biofilm efficiently and form biofilm with internal structures including pores and channels. In this work, we explore the effect of a class of synthetic analogs of rhamnolipids at controlling (promoting and inhibiting) the biofilm formation activities of a non-rhamnolipid-producing strain - rhlA - of P. aeruginosa. This class of rhamnolipid analogs is known to modulate the swarming motilities of wild-type PAO1 and rhlA mutant, but its effect on biofilm formation of rhlA mutant is unknown. We show that small structural details of these molecules are important for the bioactivities, but do not affect the general physical properties of the molecules. The bioactive synthetic analogs of rhamnolipids promote biofilm formation by rhlA mutant at low concentrations, but inhibit the biofilm formation at high concentrations. To explore the internal structures formed by the biofilms, we first demonstrate that wild-type biofilms are formed with substantial topography (hills and valleys) when the sample is under shaking conditions. Using this observation as a comparison, we found that synthetic analogs of rhamnolipids promoted structured (porous) biofilm of rhlA mutant, at intermediate concentrations between the low ones that promoted biofilm formation and the high ones that inhibited biofilm formation. This study suggests a potential chemical signaling approach to control multiple bacterial activities.

Quantification of alginate by aggregation induced by calcium ions and fluorescent polycations.

For quantification of polysaccharides, including heparins and alginates, the commonly used carbazole assay involves hydrolysis of the polysaccharide to form a mixture of UV-active dye conjugate products. Here, we describe two efficient detection and quantification methods that make use of the negative charges of the alginate polymer and do not involve degradation of the targeted polysaccharide. The first method utilizes calcium ions to induce formation of hydrogel-like aggregates with alginate polymer; the aggregates can be quantified readily by staining with a crystal violet dye. This method does not require purification of alginate from the culture medium and can measure the large amount of alginate that is produced by a mucoid Pseudomonas aeruginosa culture. The second method employs polycations tethering a fluorescent dye to form suspension aggregates with the alginate polyanion. Encasing the fluorescent dye in the aggregates provides an increased scattering intensity with a sensitivity comparable to that of the conventional carbazole assay. Both approaches provide efficient methods for monitoring alginate production by mucoid P. aeruginosa.

Chemical Signals of Synthetic Disaccharide Derivatives Dominate Rhamnolipids at Controlling Multiple Bacterial Activities.

Microbes secrete molecules that modify their environment. Here, we demonstrate a class of synthetic disaccharide derivatives (DSDs) that mimics and dominates the activity of naturally secreted rhamnolipids by Pseudomonas aeruginosa. The DSDs exhibit the dual function of activating and inhibiting the swarming motility through a concentration-dependent activity reversal that is characteristic of signaling molecules. Whereas DSDs tethered with a saturated farnesyl group exhibit inhibition of both biofilm formation and swarming motility, with higher activities than rhamnolipids, a saturated farnesyl tethered with a sulfonate group only inhibits swarming motility but promote biofilm formation. These results identified important structural elements for controlling swarming motility, biofilm formation, and bacterial adhesion and suggest an effective chemical approach to control intertwined signaling processes that are important for biofilm formation and motilities.

Clinicians' Experience with and Attitudes toward Discussing Advance Directives with Terminally Ill Patients and Their Families in a Chinese Community.

BACKGROUND: Although advance directives (ADs) are already exercised in many Western countries, cultural differences surrounding death and dying may potentially pose challenges to the implementation of ADs in a Chinese community. It is therefore relevant to explore the experience with and attitudes towards ADs of health care professionals, who are trained in Western medicine but working in a Chinese cultural setting. Hong Kong represents a unique setting for this. OBJECTIVE: The study objective was to evaluate clinicians' experience with and attitudes towards discussing ADs with terminally ill patients and their families. METHODS: In this descriptive pilot study, we conducted a cross-sectional questionnaire survey among doctors working in the largest teaching hospital at the University of Hong Kong. RESULTS: Seventy-seven out of 269 doctors working in the surveyed departments completed the questionnaire. The majority of participants (n=72; 94%) indicated willingness to initiate discussions about ADs and 62% (n=48) supported the AD to be recognized as a legally binding document but only 49% (n=38) had past experience of such discussions. CONCLUSIONS: Clinicians were generally receptive of the concept of the AD, willing to practice it clinically, and supported its legal recognition. However, AD discussions were an infrequent encounter, hence many clinicians lack experience and are unfamiliar with relevant guidelines. Large-scale studies within the health care professions as well as qualitative studies further exploring potential barriers should follow.

Specific maltose derivatives modulate the swarming motility of nonswarming mutant and inhibit bacterial adhesion and biofilm formation by Pseudomonas aeruginosa.

We have demonstrated that specific synthetic maltose derivatives activate the swarming motility of a Pseudomonas aeruginosa nonswarming mutant (rhlA) at low concentration, but inhibit it at high concentration. Although these molecules are not microbicidal, active maltose derivatives with bulky hydrocarbon groups inhibited bacterial adhesion, and exhibited biofilm inhibition and dispersion (IC50 ~20 µM and DC50 ~30 µM, respectively). Because the swarming motility of the rhlA mutant is abolished by the lack natural rhamnolipids, the swarming activation suggests that maltose derivatives are analogues of rhamnolipids. Together, these results suggest a new approach of controlling multiple bacterial activities (bacterial adhesion, biofilm formation, and swarming motility) by a set of disaccharide-based molecules.