Biosensor based on electrospun blended chitosan-poly (vinyl alcohol) nanofibrous enzymatically sensitized membranes for pirimiphos-methyl detection in olive oil.

An ultra-sensitive electrochemical biosensor was successfully developed for rapid detection of pirimiphos-methyl in olive oil, based of genetically-engineered acetylcholinesterase (AChE) immobilization into electrospun chitosan/poly (vinyl alcohol) blend nanofibers. Due to their unique properties such as spatial structure, high porosity, and large surface area, the use of nanofibers allowed improving the biosensor response by two folds. The developed biosensor showed a good performance for detecting pirimiphos-methyl, with a limit of detection of 0.2nM, a concentration much lower than the maximum residue limit allowed set by international regulations (164nM). The biosensor was used for the detection of pirimiphos-methyl in olive oil samples after a simple liquid-liquid extraction, and the recovery rates were close to 100%.

Ultra-sensitive biosensor based on genetically engineered acetylcholinesterase immobilized in poly (vinyl alcohol)/Fe-Ni alloy nanocomposite for phosmet detection in olive oil.

An ultra-sensitive screen-printed biosensor was successfully developed for phosmet detection in olive oil, based on a genetically-engineered acetylcholinesterase (AChE) immobilized in a azide-unit water-pendant polyvinyl alcohol (PVA-AWP)/Fe-Ni alloy nanocomposite. Fe-Ni not only allowed amplifying the response current but also lowering the applied potential from 80 mV to 30 mV vs Ag/AgCl. The biosensor showed a very good analytical performance for phosmet detection, with a detection limit of 0.1 nM. This detection limit is lower than the allowable concentrations set by international regulations. In addition to the good reproducibility, operational and storage stability, the developed biosensor was successfully used for the determination of phosmet in olive oil samples without any laborious pre-treatment. The phosmet recovery rate was about 96% after a simple liquid-liquid extraction.

Percutaneous endoscopic gastrostomy: strategies for prevention and management of complications.

OBJECTIVE: The placement of percutaneous endoscopic gastrostomy (PEG) tubes is within the realm of the head and neck surgeon because most are proficient in the use of rigid and flexible esophagoscopes. The ability to provide comprehensive care for the patient with head and neck cancer provides further incentive for the head and neck surgeon to adopt this technique. Although it is a technically simple procedure, the surgeon must be aware of the range of complications that can occur with PEG. We review our experience with PEG focusing on the complications as well as strategies for the prevention and management of these complications. METHODS: A retrospective review of the records of patients who underwent PEG at Stanford University by the Head and Neck Surgery Service between July 1992 and December 1998 was conducted. A total of 103 patients were identified, of which 84 (82%) were patients with head and neck cancers. Complications associated with PEG were identified. All PEGs were performed using the pull technique. RESULTS: There was no mortality associated with the procedure. Minor complications occurred in 11 cases (10.7%). These included cellulitis (4), ileus (3), tube extrusion (1), clogged lumen (1), and peristomal leakage (2). The only major complication was a single case of PEG site metastasis. CONCLUSION: The review of our experience with PEG tube placement revealed a low complication rate. Safe PEG placement was achieved by transillumination of the abdominal wall and confirmation by ballottement. In addition, appropriate patient selection, use of perioperative antibiotics, as well as meticulous post-procedure care contributed to the low rate of complications. For the patients with head and neck cancer, a barrier should be placed between the tumor and the instrumentation at the time of tube placement.

Allograft dermal implant (AlloDerm) in a previously irradiated field.

OBJECTIVE: To evaluate the integration of AlloDerm (LifeCell Corp., The Woodlands, TX) in a field exposed to external-beam radiation (EBR) by analyzing graft thickness, fibroblast recellularization, and neovascularization. STUDY DESIGN: Randomized control. METHODS: Thirty-six male Sprague-Dawley rats (n = 36) were randomly assigned to four groups. One hind leg of each rat was exposed to 20 Gy of EBR; the other limb served as the nonirradiated control. Two weeks after irradiation, AlloDerm was implanted into both hind legs. Grafts were harvested at 3, 4, 6, and 14 weeks after implantation and underwent histological analyses. RESULTS: There was no statistically significant difference in graft thickness, fibroblast count, or neovascularization between the grafts placed in the irradiated bed and the controls (n = 33, P = .332, P = .336, and P = .057, respectively). However, at week 3, fibroblast counts in the graft placed in the field exposed to EBR were significantly lower than those of controls (P = .019), although at week 14 the counts in the experimental limb were higher than those of the controls (P = .002). Graft thickness (P = .001) and fibroblast count (P < .004) were lower at week 14 than at earlier time periods for both the experimental and control grafts. CONCLUSIONS: In the rat model, graft thickness and neovascularization of the AlloDerm dermal implant do not appear to be adversely affected by a field that has received EBR. Fibroblast ingrowth may be hindered in the early postimplantation period but appears to normalize in the long term. Furthermore, overall graft thickness and fibroblast counts decrease over time, regardless of irradiation status.

Effects of external beam radiation on the allograft dermal implant.

OBJECTIVE: The purpose of this study was to define the effects of external beam radiation (EBR) on AlloDerm (LifeCell Corp) through the analysis of graft thickness, fibroblast recellularization, and neovascularization as a function of time. METHODS AND MATERIAL: Thirty-six male Sprague-Dawley rats (n = 36) were randomly assigned to 1 of 4 groups (A, B, C, and D). AlloDerm was implanted subcutaneously into the hind legs of each rat, and 20 Gy of EBR was administered to one side. Grafts harvested 1, 2, 4, and 12 weeks after radiation were subjected to blinded histologic analysis. RESULTS: In groups A, B, and C, the irradiated grafts showed a significant decrease in recellularization versus nonirradiated (P < 0.001). At 12 weeks (group D), recellularization equalized, but neovascularization was significantly less (P = 0.048) in the irradiated group. Graft thickness was unaffected. CONCLUSIONS: In the rat model, EBR of the implanted AlloDerm graft hinders recellularization in the early posttreatment period. However, EBR did not adversely affect graft thickness, recellularization or ultimate graft survival.

Occurrence of pesticides and polychlorinated biphenyls in water of the Nile river at the estuaries of Rosetta and Damiatta branches, north of Delta, Egypt.

A study was conducted from summer 1995 to summer 1997 to assess the seasonal occurrence of pesticide residues and other organic contaminants, polychlorinated biphenyls (PCBs), in water at the estuaries of Rosetta and Damiatta branches of the Nile river. The results indicated that organochlorine compounds (OCs) including HCB, lindane, p,p'-DDE, p,p'DDD, p,p'-DDT, aroclor 1254 and aroclor 1260 were present in all the water samples at concentration levels ranging between 0.195-0.240, 0.286-0.352, 0.035-0.067, 0.019-0.033, 0.024-0.031, 0.390-0.70 and 0.166-0.330 microgram/l, respectively. The levels of these compounds were higher in water of Damiatta branch than those found in water of Rosetta branch. Aldrin, dieldrin and endrin were not detected in all water samples. Only 4 compounds from 36 organophosphorus insecticides, fungicides and s-triazine herbicides tested were detected in water samples collected during summer and autumn seasons from Rosetta branch. The concentration levels of these detected compounds, dimethoate, malathion, captan, and ametryne, ranged from 0.011 to 0.340 microgram/l, respectively. Similar compounds during the same seasons as found in water of Rosetta branch were also detected in water of Damiatta branch except ametryne. The levels of the detected compounds (dimethoate, malathion and captan) ranged between 0.030 and 0.330 microgram/l. The levels of detected organophosphorus insecticides, fungicides and s-triazine herbicides were in the order: dimethoate > malathion > captan > ametryne.

A sensitive sperm-motility test for the assessment of cytotoxic effect of pesticides.

A sensitive sperm-motility test for the evaluation of cytotoxic effects of carbofuran and glyphosate in a defined protein-free culture medium is described. The sperm motility was compared to that obtained with a protein-containing medium. The use of protein-free medium considerably increased the sensitivity of sperm cells from rabbit and human to the toxic effects of the pesticide. The respective IC50 values (the concentration needed to cause 50% inhibition of sperm motility) in protein-free medium of carbofuran and glyphosate were 321 and 48.2 microM with human sperm, and 116 and 23.5 microM with rabbit sperm. Whereas, the corresponding values in protein-containing medium were 920 and 740 microM, and 910 and 500 microM with human and rabbit sperm, respectively. Our results show that testing human and rabbit sperm in protein-free medium proves to be a more sensitive method than that in protein-containing medium. Additionally, the use of rabbit sperm is a more sensitive test system than human sperm. This study suggests that the rabbit sperm test appears to have a potential for the assessment of toxicity on human reproduction.

Toxic effects of carbofuran and glyphosate on semen characteristics in rabbits.

The present study was undertaken to investigate the effect of chronic treatment with two sublethal doses of Carbofuran (carbamate insecticide) and Glyphosate (organophosphorus herbicide) on body weight and semen characteristics in mature male New Zealand white rabbits. Pesticide treatment resulted in a decline in body weight, libido, ejaculate volume, sperm concentration, semen initial fructose and semen osmolality. This was accompanied with increases in the abnormal and dead sperm and semen methylene blue reduction time. The hazardous effect of these pesticides on semen quality continued during the recovery period, and was dose-dependent. These effects on sperm quality may be due to the direct cytotoxic effects of these pesticides on spermatogenesis and/or indirectly via hypothalami-pituitary-testis axis which control the reproductive efficiency.

Treatment of pea (Pisum sativum L.) protoplasts with DNA-damaging agents induces a 39-kilodalton chloroplast protein immunologically related to Escherichia coli RecA.

Organisms must have efficient mechanisms of DNA repair and recombination to prevent alterations in their genetic information due to DNA damage. There is evidence for DNA repair and recombination in plastids of higher plants, although very little is known at the biochemical level. Many chloroplast proteins are of eubacterial ancestry, suggesting that the same could be true for the components of a DNA repair and recombination system. A 39-kD protein, immunologically related to Escherichia coli RecA, is present in chloroplasts of pea (Pisum sativum L.). Bandshift gel assays suggest that it binds single-stranded DNA. Its steady-state level is increased by several DNA-damaging agents. These results are consistent with it being a plastid homolog of E. coli RecA protein, presumably involved in DNA repair and recombination, and with the existence of an SOS-like response in pea leaf cells. Experiments with protein synthesis inhibitors suggest that the 39-kD chloroplast protein is encoded in the nucleus.