Study on a one-dimensional defective photonic crystal suitable for organic compound sensing applications

Organic-compound-based sensors have important applications, such as applications in geothermal power stations, the shoe industry, the extraction of vegetable oil, azeotropic calibration and medical science. Herein, a 1D photonic crystal (PC) with a defect has been used to develop a photonic-technology-based organic compound sensor with optimum performance. The structure of the proposed organic compound sensor consists of a water cavity sandwiched between two symmetric sub-PCs, which are composed of alternate layers of SiO₂ and ZnO. The proposed air/(SiO₂/ZnO)⁵/cavity/(SiO₂/ZnO)⁵/glass structure with the optimized structural parameters achieves a quality factor that varies between a minimum value of 4968.2 and a maximum value of 6418.5. The FOM and sensitivity values of the proposed sensing design are on the order of 10² and 10³, respectively. The LOD value of the proposed sensor is on the order of 10⁻⁵, which is very low, as is always expected for chemical sensing designs. Thus, the simple design and excellent performance make our design highly efficient and suitable for sensing applications in the industrial and biomedical fields.

Organic-compound-based sensors have important applications, such as applications in geothermal power stations, the shoe industry, the extraction of vegetable oil, azeotropic calibration and medical science.     

Nanobiotic formulations as promising advances for combating MRSA resistance: susceptibilities and post-antibiotic effects of clindamycin,doxycycline, and linezolid

Antimicrobial activity and post-antibiotic effects (PAEs) are both important parameters in determination of the dosage regimen of antimicrobial agents. In the present study, antimicrobial activity and PAEs of clindamycin, doxycycline, linezolid, and their nanobiotic formulations were evaluated against two methicillin resistant Staphylococcus aureus clinical isolates (MRSA) encoded (MRSA-S1 and MRSA-S2). Nanobiotic formulations increased the susceptibility of MRSA isolates by 4–64 folds as compared to their conventional ones. The PAE values were determined after exposure of MRSA isolates for 1 h to 10× the MICs of the tested antibiotics. The duration of PAEs were recorded after bacterial growth in Mueller Hinton broth (MHB) free from antibiotic has been restored. The PAE values for MRSA-S1 were 2.5 h for the conventional antibiotics. However, the PAEs for nanobiotics were 4 h for both clindamycin and linezolid, while 3 h for doxycycline. For MRSA-S2, linezolid and linezolid nanobiotics PAEs were 3 h. PAEs of clindamycin and clindamycin nanobiotics were 3.75 h and 4 h, respectively. Doxycycline and doxycycline nanobiotics revealed the same PAEs patterns of 3.5 h. The findings of the current study may positively influence the pharmacodynamics of the antibiotics and consequently the dosage regimen of nanobiotics as well as on their clinical outcome.

Novel nanobiotic formulations of clindamycin, doxycycline, and linezolid were evaluated for the post-antibiotic effects against biofilm forming methicillin resistant Staphylococcus aureus (MRSA).     

Role of peritoneal ultrasonography and ultrasound-guided fine needle aspiration cytology/biopsy of extravisceral masses in the diagnosis of ascites of undetermined origin

Background and study aimsAscites may be of undetermined origin despite comprehensive study. This study aimed to assess the accuracy and safety of conventional and interventional high-frequency peritoneal ultrasound in the diagnosis of patients with ascites of unclear origin.Patients and methodsA total of 62 patients were prospectively enrolled; they underwent conventional (3.5–5 MHz) and high-frequency (6–8 MHz) transabdominal peritoneal ultrasound to suggest the nature of ascites supplemented by fine needle aspiration cytology (FNAC) of ascites and/or core biopsy of the omentum or other extra-visceral masses for final histopathologic diagnosis. Laparoscopy or laparotomy was needed if biopsy was inconclusive.ResultsUltrasound-guided procedures were diagnostic in 55 (87.7%) patients. Thirty-six (58.1%) were benign, of whom 86% had tuberculous peritonitis, 26 (41.9%) were malignant, of whom 76.9% had peritoneal metastasis. High-frequency ultrasound was able to propose ultrasonographic criteria in a trial to diagnose the nature of ascites. Our proposed ultrasonographic criteria were based on the amount and texture of ascites in addition to the omental and mesenteric features. These were able to suggest the diagnosis with 80.7% sensitivity for malignant ascites and 75% specificity for benign ascites. Moreover, histopathological examination of tissues obtained by ultrasound-guided procedures increased the sensitivity to 88.5% and the specificity to 88.9% in diagnosing malignant and benign disease, respectively, with an overall diagnostic accuracy of 88.6%. These procedures were considered to be safe as only one major (haemoperitoneum) and two minor complications (temporary ascitic fistula) were reported.ConclusionHigh-frequency peritoneal ultrasound together with the minimally invasive ultrasound-guided FNAC/biopsy of extra-visceral lesions may be considered an effective and safe tool in the diagnosis of ascites of undetermined origin.     

Comparative antibacterial efficacy of a 2-minute surgical scrub with chlorhexidine gluconate, povidone-iodine, and chloroxylenol sponge-brushes

Chlorhexidine gluconate (Hibiclens), povidone-iodine (E-Z Scrub 201), and chloroxylenol (ParaSoft) sponge-brushes were compared for antibacterial efficacy in 2-minute surgical scrubs. Thirty-nine volunteers completed a 7-day baseline period and a 5-day treatment period. Thirteen participants were assigned to a chlorhexidine group, 12 to a povidone-iodine group, and 14 to a chloroxylenol group. Subjects followed a standardized protocol, performing 11 scrubs during the treatment period. Bacterial counts were taken by the glove-juice procedure immediately after scrubbing and at 3 and 6 hours later on days 1, 2, and 5. The use of chlorhexidine achieved significantly (p less than 0.01) greater adjusted mean log10 bacterial count reductions than did povidone-iodine and chloroxylenol at all sampling times, with greater reductions as the study progressed.     

Restriction of bacterial growth under commercial catheter dressings

The effect on the normal cutaneous flora after iodine and alcohol disinfection of the skin of three commercially available moisture-permeable polyurethane dressings was compared with that of a gauze-and-tape dressing. Dressings also were evaluated clinically for membrane adhesion and skin erythema, pruritis, hyperpigmentation, vesiculitis, and tenderness. Each of 50 healthy volunteers and 49 long-term inpatients, 25 of whom were receiving antibiotic therapy, received simultaneously on their volar forearm patches of Op-Site, Tegaderm, Uniflex, and gauze dressings. Controls consisted of one exposed skin site and one covered with moisture-retaining vinylidene film (Saran Wrap). Although after 3 days of adhesion, commercial dressings prevented indigenous flora from returning to normal population densities, no significant quantitative differences were found between them and the gauze-and-tape dressing. Generally, all clinical dressings maintained normal flora at one tenth the population of the uncovered site; the Saran Wrap control supported 100-fold more bacteria than the exposed site. No differences were discovered in the levels of gram-negative bacteria, or among patient groups and between patients and healthy subjects, except for the lower incidence of erythema and itching among patients compared with healthy subjects.     

Preoperative biliary drainage before resection in obstructive jaundice

BACKGROUND: Surgery for patients with malignant obstructive jaundice carries high morbidity and mortality rates. Preoperative biliary drainage (PBD) has been used in an attempt to improve the outcome in these patients. AIM: To review the evidence in the literature on whether PBD improves postoperative morbidity and mortality in obstructive jaundice patients. MEHOD: Using Medline a literature search was performed for papers published in English from January 1980 to October 2000, using the text words 'obstructive jaundice', 'preoperative', 'drainage' and 'stent'. All retrieved papers which reported experimental or clinical observations relevant to the study aim were carefully analysed and the findings are summarised in this review. RESULTS AND CONCLUSION: There is no evidence in the literature to support the view that routine PBD improves postoperative morbidity and mortality in patients with obstructive jaundice undergoing resection. PBD has its own complications that cancel out its benefits. However, PBD could be beneficial in patients presenting with sepsis, coagulation abnormalities or malnutrition.