Probing the biofunctionality of biotinylated hyaluronan and chondroitin sulfate by hyaluronidase degradation and aggrecan interaction

Molecular interactions involving glycosaminoglycans (GAGs) are important for biological processes in the extracellular matrix (ECM) and at cell surfaces, and also in biotechnological applications. Enzymes in the ECM constantly modulate the molecular structure and the amount of GAGs in our tissues. Specifically, the changeable sulfation patterns of many GAGs are expected to be important in interactions with proteins. Biotinylation is a convenient method for immobilizing molecules to surfaces. When studying interactions at the molecular, cell and tissue level, the native properties of the immobilized molecule, i.e. its biofunctionality, need to be retained upon immobilization. Here, the GAGs hyaluronan (HA) and chondroitin sulfate (CS), and synthetically sulfated derivatives of the two, were immobilized using biotin-streptavidin binding. The degree of biotinylation and the placement of biotin groups (end-on/side-on) were varied. The introduction of biotin groups could have unwanted effects on the studied molecule, but this aspect that is not always straightforward to evaluate. Hyaluronidase, an enzyme that degrades HA and CS in the ECM, was investigated as a probe to evaluate the biofunctionality of the immobilized GAGs, using both quartz crystal microbalance and high-performance liquid chromatography. Our results showed that end-on biotinylated HA was efficiently degraded by hyaluronidase, whereas already a low degree of side-on biotinylation destroyed the degrading ability of the enzyme. Synthetically introduced sulfate groups also had this effect. Hence hyaluronidase degradation is a cheap and easy way to investigate how molecular function is influenced by the introduced functional groups. Binding experiments with the proteoglycan aggrecan emphasized the influence of protein size and surface orientation of the GAGs for in-depth studies of GAG behavior.     

A randomized open-label trial of on-demand rabeprazole vs ranitidine for patients with non-erosive reflux disease

AIM: To compare the efficacy of the proton-pump inhibitor, rabeprazole, with that of the H₂-receptor antagonist, ranitidine, as on-demand therapy for relieving symptoms associated with non-erosive reflux disease (NERD).METHODS: This is a single center, prospective, randomized, open-label trial of on-demand therapy with rabeprazole (group A) vs ranitidine (group B) for 4 wk. Eighty-three patients who presented to the American University of Beirut Medical Center with persistent gastroesophageal reflux disease (GERD) symptoms and a normal upper gastrointestinal endoscopy were eligible for the study. Patients in group A (n = 44) were allowed a maximum rabeprazole dose of 20 mg twice daily, while those in group B (n = 39) were allowed a maximum ranitidine dose of 300 mg twice daily. Efficacy was assessed by patient evaluation of global symptom relief, scores of the SF-36 quality of life (QoL) questionnaires, total number of pills used, and number of medication-free days.RESULTS: Among the 83 patients who were enrolled in the study, 76 patients (40 in the rabeprazole group and 36 in the ranitidine group) completed the 4-wk trial. Baseline characteristics were comparable between both groups. After 4 wk, there was no significant difference in the subjective global symptom relief between the rabeprazole and the ranitidine groups (71.4% vs 65.4%, respectively; P = 0.9). There were no statistically significant differences between mean cumulative scores of the SF-36 QoL questionnaire for the two study groups (rabeprazole 22.40 ± 27.53 vs ranitidine 17.28 ± 37.06; P = 0.582). There was no significant difference in the mean number of pills used (rabeprazole 35.70 ± 29.75 vs ranitidine 32.86 ± 26.98; P = 0.66). There was also no statistically significant difference in the mean number of medication-free days between both groups.CONCLUSION: Rabeprazole has a comparable efficacy compared to ranitidine when given on-demand for the treatment of NERD. Both medications were associated with improved quality of life.     

Role of Splenic Artery Embolization in Management of Traumatic Splenic Injuries: A Prospective Study

The objective of our study was to evaluate the role of splenic artery embolization (SAE) in the management of traumatic splenic injuries. From September 2008 to September 2010, a total of 67 patients underwent nonoperative management (NOM) for blunt splenic injuries. Twenty-two patients were excluded from the study because of associated significant other organ injuries. Twenty-five patients underwent SAE followed by NOM (group A) and 20 patients underwent standard NOM (group B). Improvement in clinical and laboratory parameters during hospital stay were compared between two groups using Chi-square test and Mann–Whitney test. SAE was always technically feasible. The mean length of the total hospital stay was lower in the group A patients (5.4 vs. 6.6 day, [P = 0.050]). There was significant increase in hemoglobin and hematocrit levels and systolic blood pressure (SBP) in group A patients after SAE, whereas in group B patients there was decrease in hemoglobin and hematocrit levels and only slight increase in SBP (pre- and early posttreatment relative change in hemoglobin [P = 0.002], hematocrit [P = 0.001], and SBP [P = 0.017]). Secondary splenectomy rate was lower in group A (4 % [1/25] vs. 15 % [3/20] [P = 0.309]). No procedure-related complications were encountered during the hospital stay and follow-up. Minor complications of pleural effusion, fever, pain, and insignificant splenic infarct noted in 9 (36 %) patients. SAE is a technically feasible, safe, and effective method in the management of splenic injuries. Use of SAE as an adjunct to NOM of splenic injuries results improvement in hemoglobin, hematocrit levels, and SBP. SAE also reduces secondary splenectomy rate and hospital stay.Keyword: Trauma, Splenic artery embolisation     

Detection of New Delhi Metallo‐beta‐Lactamase and Extended‐Spectrum beta‐Lactamase Genes in Escherichia coli Isolated from Mastitic Milk Samples

In this study, eight Escherichia coli isolates were obtained from milk samples of dairy cattle suffering from clinical/subclinical mastitis. Isolates were characterized for antimicrobial resistance traits and virulence genes. Results revealed that one isolate was harbouring New Delhi metallo‐beta‐lactamase gene (bla_NDM). Cloning and sequencing of the PCR amplicon confirmed the identity of the gene (GenBank accession no. KC769583 ) having 100% homology with bla_NDM‐5 (GenBank accession no. JN104597.1 ), and this isolate was susceptible to colistin, chloramphenicol and tetracycline only. Moreover, another isolate carried extended‐spectrum beta‐lactamase (ESBL) gene – bla_CTX‐M, and all isolates possessed bla_TEM gene. Of the eight isolates, only one isolate was positive for shiga toxin gene (stx2), and none were harbouring stx1 gene. Occurrence of New Delhi metallo‐beta‐lactamase (bla_NDM) in one E. coli isolate and ESBL genes in other isolates poses a potential threat to human health following possible entry and spread through food chain.     

Gesture and aphasia: Helping hands?

Background: The study of communicative gestures is one of considerable interest for aphasia, in relation to theory, diagnosis, and treatment. Significant limitations currently permeate the general (psycho)linguistic literature on gesture production, and attention to these limitations is essential for both continued investigation and clinical application of gesture for people with aphasia.

Aims: The aims of this paper are to discuss issues imperative to advancing the gesture production literature and to provide specific suggestions for applying the material herein to studies in gesture production for people with aphasia.

Main Contribution: Two primary perspectives in the gesture production literature are distinct in their proposals about the function of gesture, and about where gesture arises in the communication stream. These two perspectives will be discussed, along with three elements considered to be prerequisites for advancing the research on gesture production. These include: operational definitions, coding systems, and the temporal synchrony characteristics of gesture.

Conclusions: Addressing the specific elements discussed in this paper will provide essential information for both continued investigation and clinical application of gesture for people with aphasia.     

The relationship of structure,thermal and water vapor permeability barrier properties of poly(butylene succinate)/organomodified beidellite clay bionanocomposites prepared by in situ polycondensation

The exploitation of beidellite clay (BDT), used as a nanofiller in the preparation of poly(butylene succinate) (PBS)/organoclay biodegradable nanocomposites, was investigated. A series of bionanocomposites with various loadings of the organoclay (3CTA-BDT) were prepared by in situ polycondensation reaction between succinic anhydride (SuAh) and 1,4-butanediol (1,4-BD) at atmospheric pressure in refluxing decalin with azeotropic removal of water, and the reaction was catalyzed by non-toxic bismuth chloride (BiCl₃). X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that 3CTA-BDT was likely exfoliated and well dispersed in PBS matrix. Thermal properties (TGA, DSC and thermal conductivity), contact angle measurements and water vapor sorption behavior of the corresponding nanocomposites were also discussed. Compared to pure PBS, a significant reduction of the diffusion coefficient and the water vapor permeability (WVP) by 44 and 37%, respectively, was observed by adding only 5 wt% of 3CTA-BDT. These results could make these bionanocomposites suitable materials for food packaging application.

The exploitation of beidellite clay (BDT), used as a nanofiller in the preparation of poly(butylene succinate) (PBS)/organoclay biodegradable nanocomposites, was investigated. Their thermal and water vapor barrier properties were also studied.     

Evaluation of the antiparasitic activities of imidazol-2-ylidene–gold(I) complexes

A series of cationic gold(I)–carbene complexes with various 4,5-diarylimidazolylidene ligands were either newly prepared or repurposed for testing against protozoal Leishmania major, Toxoplasma gondii, and Trypanosoma brucei parasites. The syntheses of the new complexes 1b and 1c were described. Ferrocene compound 1a showed the highest activities against L. major amastigotes and T. gondii and distinct selectivity for T. gondii cells when compared with the activity against nonmalignant Vero cells. The ferrocene derivatives 1a–c are generally more active against the L. major amastigotes and the T. gondii tachyzoites than the other tested anisyl gold complexes and the approved drugs atovaquone and amphotericin B. Compounds 1a and 1e showed the highest selectivities for L. major amastigotes. Compounds 1d and 1f showed the highest selectivities for L. major promastigotes; 1f was the most active compound against L. major promastigotes of this series of compounds. The 3,4,5-trimethoxyphenyl analog 1b also exhibited a much greater selectivity for T. b. brucei cells when compared with its activity against human HeLa cells.