Lead removal by ThioOctolig

Octolig, a commercially available (a polyethylene diamine covalently attached to silica gel), was subjected to modifications to incorporate sulfur for enhanced removal of lead ion from aqueous solutions. The basic approach was attempted formation of "ThioOctolig" by the reaction of Octolig with thioacetamide in toluene using a shaker bath for 24 or 48 h or in the presence of 10% HCl (1 h). Our experience was that conversion was limited to about 20% based on sulfur analysis for 24 or 48 h reaction time, or in the presence of 10% HCl. In fact, with acidification, the results were poorer. Duplicate runs indicated consistent results. Literature reported that SbCl₃ was an effective catalyst with a reaction time of 1 h. Use of this reagent (1-h reaction time) produced a bright orange red product, in contrast with previous yellow-colored products. A control run indicated that this reagent reacted with Octolig in toluene (in the dark) to produce a red-colored sample; thioacetamide reacted to produce a yellow sample. Use of SbCl₃ (∼5 mole %) did not enhance the sulfur content of Octolig. A sample of Octolig removed 68% lead ion from a 120 ppm aqueous lead while a sample of ThioOctolig (10% S) removed 99.4% lead ions. We also investigated enhancing the sulfur incorporation upon raising the reaction temperature with thioacetamide.

Cheating and Its Dangers

Theses (dissertations and masters' theses) can be particularly important resources because they represent sources of detailed information that may not be included in a communication of an article in a highly popular journal, owing to space limitations. In addition, a thesis is a document presumably prepared under supervision of an experienced faculty member with the aid of a committee of faculty peers. The supervisory committee constitutes an in-house group of experts who can prevent mistakes from being disseminated, as editors and reviewers do for articles sent to journals. Unfortunately, the value of a thesis may be limited when committee members do not perform their traditional functions, when students cheat, or when students commit plagiarism. Examples of these problems are presented as case studies and as cautionary examples. In addition, suggestions are made to limit damage that can be caused by those guilty of less than exemplary behavior.

Efficacy of Octolig chromatography as a means of removal of aqueous antibiotics given to premature babies

Reliable information indicated that a half-million prematurely born babies are routinely given antibiotics without evidence of infection. This study is based on a concern that such antibiotics might go into hospital waste systems and lead to antibiotic-resistant bacteria. We tested the removal of selected antibiotics by Octolig, a commercially available supported chelating agent using column chromatography. Five (Caffeine, Ampicillin, Furosemide, Dopamine, and Vancomycin) were selected for study. Ampicillin and Furosemide were quantitatively removed by column chromatography. Dopamine, Caffeine, and Vancomycin were failures. Failures are ascribed to inadequate pK_a values (<5) for these three antibiotics.

Efficacy of removal of a popular NSAID from aqueous solutions with metalloligs

Acetaminophen, a popular NSAID (Non-steroidal anti-inflammatory drug), was studied for efficacy of removal from aqueous solutions. While Octolig® (a polyethylenediimine covalently attached to silica gel) is able to remove many simple anions and some acidic pharmaceuticals having a pK_a value less than 4.5, it lacked efficacy with acetaminophen. Accordingly different transition- metal derivatives of Octolig® were tested by column chromatography using as substrates Octolig® derivatives of copper(II), cobalt(II), iron(III), manganese(II), nickel(II), and zinc(II).

Efforts to remove aqueous lithium ion using Octolig® and methylated derivatives

Aqueous Li⁺ - containing samples (in DI water or well water) were eluted over Octolig®, a polyethylenediimine covalently attached to a high- surface-area silica gel, and only slight removal, if any, could be claimed. However, when using tetrahydrofuran (THF) as a solvent we quantitatively removed lithium ion with Octolig® or with alkylated Octolig®, demonstrating the efficacy of Octolig® and lack of advantage of a N, N'-dialkylated Octolig®. In addition, the removal of alkali metal ions (lithium, sodium, and potassium) in THF by Octolig® was partially selective: While being quantitative for lithium it was only about 40% for potassium. The study has potential implications for using geothermal brines not only as a heat source, but as a source of lithium as well.

Removal of phosphate from electrocoagulation post-treatment phosphate reduction using Octolig®

The present study examined the removal of phosphorus following electrocoagulation post-treatment using a sample from a commercial firm. Samples were subjected to column chromatography using Octolig® a polyethylenediimine covalently attached to high-surface-area silica. Two commercial samples with significantly different phosphorus concentrations were evaluated: 10.2 ppm from polyphosphates and raw sample of 983 ppm P. After passing over Octolig®, the sample phosphate concentration was reduced to values of <0.05 ppm P.

Removal of a common antibiotic (Amoxicillin) from different aqueous systems using Octolig®

Amoxicillin, used to manage bacterial infection, is among the top five popular pharmaceuticals in the United States, based on the number of prescriptions. Problems with environmentally available drugs can arise chiefly; biological resistance in excess amounts becomes available in wastewater samples. Previously, we observed that Amoxicillin could be removed quantitatively from deionized water by passage over Octolig®, a polythylenediimine covalently attached to high-surface-area silica gel. This study was concerned with testing the potential removal of Amoxicillin in different solutions (tap water, well water, river water, and the weakly saline water). These solutions were passed over chromatography columns at a rate of 10 mL per minute; 50-mL fractions were collected and analyzed for total dissolved solids and pH as well as concentration. As noted in our previous work, the percentage removal was related to the length of the column, and this aspect was evaluated again. Consistent results were obtained for DI water, tap water, well water, and river water, indicating quantitative removal, and but not artificial bay water, presumably because of ion competition.

Removal of selected NSAIDs (nonsteroidal anti-inflammatory drugs) in aqueous samples by Octolig®

The possibility of removing representative nonsteroidal anti-inflammatory drugs (NSAIDs) from water was tested using Octolig®, a commercially available material with polyethylenediimine moieties covalently attached to high-surface area silica gel. The effectiveness of removal should depend on selected NSAIDs having appropriate anionic functional groups. NSAIDs selected had aromatic carboxylic groups: diclofenac, fenoprofen, indomethacin, ketoprofen, mefenamic acid, naproxen, and sulindac. These substances in deionized (DI) water were removed by passage over Octolig columns with removal values approaching 90% at environmental pH values, e.g., ca pH 6. Fenoprofen, however, was only removed to an extent of 80% in DI water and 62% in well water, presumably a result of competition with bicarbonate ions.

Removal of pain-relieving drugs from aqueous solutions using Octolig and selected metalloligs

The possibility of removing certain pharmaceuticals (acetaminophen and naproxen) from water was tested using Octolig, a commercially available material with polyethylenediimine moieties covalently attached to high-surface area silica gel. In addition, the efficacy of two transition metals (cupric and ferric) derivatives of Octolig was tested. Previously amoxicillin had been successfully subjected to column chromatography for removal by means of ion encapsulation, the effectiveness of which would depend upon having appropriate anionic functional groups. Both pharmaceuticals were removed by passage over Octolig columns, though with less effectiveness than was achieved previously with xanthenylbenzenes or selected food dyes. Somewhat greater removal, ca 90%, was achieved using Cuprilig, the copper(II) derivative, but not with Ferrilig the iron(III) derivative, perhaps because the hydroxide counter ion was more closely associated with the transition metal ion and was not available to assist in proton removal.

Enhanced removal of aqueous BPA model compounds using Metalloligs

A model compound, 4-(t-butyl)phenol, was used as a substitute for BPA (bisphenol acetone or Bisphenol A) a material used for the production of a large volume of common plastics. Unfortunately, BPA is suspected to have estrogenic properties, and there is a suspicion that even small amounts can have a deleterious effect against humans, especially female infants. The model compound has some similarities to BPA, but lacks some of the serious properties of BPA dust. Since other workers have demonstrated the capability of removing BPA from plastics by extraction with saline or alcohol, we studied whether Octolig, a polyethylenediimine supported on silica gel, or transition metal derivatives of Octolig could be used to remove concentrations for model compounds from aqueous solution. Octolig gave modest results 20%, the manganese (II) and iron (III) derivatives gave poor results, Cuprilig was an improvement over those two Metalloligs, but the cobalt(II) derivative was able to remove up to 56% of the model compound. Two methods were studied, batch and column chromatography. Under the conditions used in this study, the batch method was superior.

Removal of synthetic food dyes in aqueous solution by Octolig

We studied six of the seven food dyes commonly used, e.g., FD&C Blue No. 1 and No. 2, Green No. 3, Red No. 3 and No. 40, Yellow No. 5 and No. 6. Quantitative removal was achieved by passage of dyes in aqueous solutions over chromatography columns packed with Octolig, a polyethylenediimine covalently attached to high-surface-area silica. A structural feature most of the dyes have in common are the presence of sulfonate groups attached to aromatic molecules. Prior studies and the current one indicated that the seventh food dye (Green No. 3) should also be quantitatively removed. Matrix effects were considered, but none were observed.

Synergism between corticosteroids and Rapamycin for the treatment of intraocular inflammation

The authors studied the combination effect of corticosteroids with the new immunosuppressant Rapamycin for the treatment of intraocular inflammation. A median-effect analysis, of the combined effect of Rapamycin and dexamethasone, was performed on the inhibition of lymphocyte proliferation in culture. The mathematical formulas allowed for the calculation of combination indices and dose-reduction factors. On the basis of these in-vitro results, treatment with reduced doses of drugs in combination was evaluated in the rat model of experimental autoimmune uveoretinitis. The results showed that Rapamycin and dexamethasone were synergistic over a wide concentration range. The calculated dose reduction factors indicated that an equivalent inhibition of lymphocyte proliferation was achieved with a combination of Rapamycin and dexamethasone reduced by 5-7 and 3-6 fold respectively, compared to the concentration required when each drug was used alone. In animals, there was a significant reduction of the incidence and severity of ocular inflammation with low doses of the drugs in combination. The authors conclude that the observed synergistic effect between Rapamycin and dexamethasone suggests that the use of this drug combination might be advantageous in the treatment of patients with severe uveitis.

Inhibition of cellular transfer of experimental autoimmune uveoretinitis by Rapamycin

The crucial role of CD4(+) T cells in mediating uveitis is well recognized. One treatment strategy of non-infectious uveitis therefore seeks to inhibit T cell function. For that purpose the authors have evaluated the efficacy of Rapamycin (RAPA), an inhibitor of lymphocyte response to growth factors. To reproduce as best as possible the immune system condition during active disease, the adoptive transfer of activated T cells was used to induce experimental autoimmune uveoretinitis (EAU). Treatment with RAPA was delivered by continuous intravenous infusion. The results showed a complete inhibition of EAU transfer at the RAPA dose of 0.1 mg/kg/day. They indicate that RAPA could be a useful immunosuppressant for uveitis therapy.

Removal of BPA model compounds and related substances by means of column chromatography using Octolig®

Octolig®, a polyethylenediimine ligand covalently attached to high-surface area silica gel, was used to study the removal of phenolic compounds from aqueous samples by column chromatography. Model phenolic compounds of Bisphenol A (BPA), 4-isopropylphenol and 4-(t-butyl) phenol, were selected for this study due to their similarities in pKa and log P values. The percent removal of these compounds by Octolig® was 26 ± 2 and 22 ± 2, respectively. Furthermore, the three isomers of nitrophenol were investigated as well as additional phenolic compounds, such as amoxicillin and five phenolic dyes. These compounds have a pKa range of 2-10.2. The compounds that have pKa values less than 8.3 were able to be completely removed by Octolig®, yet compounds with pKa values of 8.3 and higher resulted in approximately 20-26% removal.

Studies on the removal of Lissamine Green B from clays and soil in comparison with contemporary approaches

A combination of Fenton's reagent with electrochemistry has been demonstrated to be a efficient method for removing a dye (Lissamine Green B) from clays (kaolin, montmorillonite) and soil. The two-step approach described here involved quantitative extraction with hot water, followed by quantitative removal of the Lissamine Green dye by column chromatography using Octolig®. The advantage of this procedure is success without the need for Fenton reagents or electricity. A disadvantage is the process would not work with polycyclic hydrocarbons such as phenanthrene, though the electro-Fenton degradation does.

Comparison of anion removal capacities of Octolig and Cuprilig

Mixtures of sodium salts of phosphate, arsenate, and fluoride were used in chromatography and batch experiments to compare the capacity of two immobilized ligands (IMLIGs) to remove these anions: Octolig and its copper (II)-based metallolig, Cuprilig. The focus of this study was twofold. First, to find out which material, Octolig or Cuprilig, would remove these anions most effectively; and secondly to determine the optimal capacity for removal of representative anions. Removal capacity was evaluated by two methods: by chromatography and by a batch method. The methods gave identical results, but the batch method was more convenient. Cuprilig had a lower capacity for removal of phosphate than Octolig. The capability of Octolig for removing anions was: phosphate > arsenate > fluoride >>> chloride >>>> bromide. Replication of phosphate removal was good for a given batch of Octolig. Of three different samples of Octolig, two seemed to be alike based on the phosphate- removal capacity; the third was different on the basis of a Student's t-test. This distinction indicates the batch procedure could serve as a quality control/assurance technique.

Removal of selected nuisance anions by Octolig

Octolig, a commercially available immobilized ligand (IMLIG), has been studied for its effectiveness in removing nuisance anions. The material consists of polyethylenediamines covalently linked to high surface-area silica, and has a high affinity for transition metal ions. Previous research indicated that anions could be removed quantitatively from aqueous solutions using the metal derivatives of Octolig as packing in column chromatography. The present study focused on the results with Octolig alone. Quantitative removals (> 99%) were obtained for arsenate, chromate, paramolybdate, selenious acid, and fluoride. Boric acid was not removed by under similar conditions, but previously the copper(II) derivative of Octolig had been partially successful. A mechanism of removal is proposed.

Comparative ease of separation of mixtures of selected nuisance anions (nitrate, nitrite, sulfate, phosphate) using Octolig

Mixtures of sodium salts of nitrate, nitrite, sulfate, and phosphate were prepared in relative amounts present in atomic waste containers with a view to effect removal by chromatography over Octolig, commercially available material with polyethylenediamine moieties covalently attached to high-surface area silica gel. Separation was attempted using aqueous solutions and column chromatography with Octolig. It is presumed that this material is capable of removing the anions by means of encapsulation. Matrix effects were tested by varying the relative concentrations. Rates of elution were varied 5-fold without adverse effect. The order of selectivity was found to be phosphate > sulfate > nitrite > nitrate through experiments altering the volume and relative concentrations. Quantitative removal of all anions (375 ppm of each) could be achieved given reasonable volumes of Octolig. An effort at regeneration by altering the pH of the eluant indicated the stability of the encapsulated anions.

Effectiveness of removal of aqueous perchlorate by Cuprilig, a copper(II) derivative of Octolig

The present study describes the effectiveness of removal of perchlorate ion by Octolig a commercially available immobilized ligand, IMLIG, and by Cuprilig, the cupric ion derivative of this material. Octolig consists of polyethylenediamine moieties covalently bound to a high-surface area silica gel (CAS Registry number = 404899-06-5). Perchlorate in drinking water is a nuisance anion that escapes from firms that produce rocket fuel, batteries, and fireworks and becomes a contaminant of groundwater. It may also be a natural component of the environment. Perchlorate ion can interfere with thyroid function and may also cause birth defects. Perchlorate contamination of water supplies is serious because of the difficulty in removing it, especially in the western United States where a combination of drought and water shortages exacerbate the problems of supplying safe drinking water to an increasing population. In this study, aqueous solutions were passed over a chromatography column containing samples of Cuprilig. Test water contained 70 microg perchlorate/L and effluent was below detection level (< 1 microg/L. Equally good results were obtained for Octolig in deionized water and in well water. Analyses were performed by a commercial laboratory. Mechanisms of interaction are proposed.

Comparison of effectiveness of removal of nuisance anions by metalloligs, metal derivatives of Octolig

The present study describes the effectiveness of removal of selected aqueous anions by several metalloligs, i.e., metal derivatives of a commercially available immobilized ligand, IMLIG, Octolig. This material consists of polyethylenediamine moieties covalently bound to a high-surface area silica gel (CAS Registry number = 404899-06-5). The metals involved are copper, cobalt, iron, nickel, manganese, and thorium. The nuisance anions, studied as aqueous solutions, were arsenate, orthophosphate, selenite, sulfate, nitrate, and nitrite. All six metalloligs tested were able to remove arsenate (280 ppb, > 99% removal) effectively. The effectiveness for other anions varied, but all anions were removed by one metallolig or another. For example, for Colbaltilig, in deionized water samples, removal was 96% for 20.9 ppm NO(3)-N, 98% for 29.6 ppm sulfate (as sodium sulfate). For Cuprilig, removal was 98% for 9.82 ppm boron as boric acid, > 99% for Cr as 212 ppm dichromate, 97% for P as 10 ppm HPO(4)-P, and 90% for sulfate as 29 ppm sulfate. Removal of nitrate by Cobaltilig appeared to be adversely affected by the presence of sulfate. Manganilig and Nickelig were able to remove > 97% of 10 ppm P as Na(2)HPO(4). Mechanisms of interaction are proposed that suggest six types of behavior and several classes of materials are represented by these metalloligs.

Removal of nuisance aqueous anions with Ferrilig

The present study describes an improved synthesis of Ferrilig, an iron(III) salt of a commercially available immobilized ligand, IMLIG, called Octolig. The resulting composite, called "Ferrilig" was used to remove arsenate, chromate, molybdate, and selenite ions from aqueous solutions by means of column chromatography. The synthesis of Ferrilig was accomplished by treating an aqueous suspension of Octolig-21 with an equal weight of ferrous sulfate heptahydrate under nitrogen. The ferrous salt was then collected by sieving and allowed to oxidize to the iron (III) salt by exposure to air; treatment with dilute sodium hydroxide converted the composite to the hydroxide. Using 300 ppb As (as Na(2)HAsO(4).7H(2)O) and column chromatography, the arsenic concentration in the effluent was less than the detection limit (< 2 ppb). Chromium as sodium chromate, molybdenum as (NH(4))(6) Mo(7)O(24).4H(2)O, and selenium as Na(2)Se0(3), were removed with fair success. The elements, their initial concentrations and their percentage removal (parenthetically) were: As (280 ppb, 99%), Cr (50.6 ppm, 95.5%), Mo (50.7 ppm, 94.6%), Se (258 ppm, 99.9%).

Ventralex mesh in umbilical/epigastric hernia repairs: clinical outcomes and complications

BACKGROUND

Umbilical and epigastric hernias have historically been repaired without mesh resulting in recurrence rates in some series of up to 40%. Recent data suggests mesh repair of these hernias may decrease recurrent hernia rates. Ideal placement of the mesh is behind the defect, which is difficult to do without a large incision in these hernias unless done laparoscopically. The Ventralex hernia patch is a composite PTFE/polypropylene patch allowing intraperitoneal placement behind the hernia defect through a small incision, and without the cost of laparoscopy. To date, only one study exists evaluating this new prosthesis.

METHODS

This study is a retrospective chart review of all umbilical and epigastric hernias repaired with the Ventralex hernia patch by a single surgeon. Patient characteristics and operative and post-operative data were collected. Hernia recurrence is the primary outcome. Secondary outcomes include complication rates.

RESULTS

Eighty-eight patients from 2003-2006 were evaluated. The population included patients aged 25-86 (mean 52) with nineteen females (22%). The average BMI was 32 (range 18-68). Eighteen patients were smokers, five patients were diabetic, and two patients were chronic steroid users. The size of patches used were small (72%), medium (27%), and unknown (1%). Average operating room time was 52 min (range 19-194). The different types of hernias repaired were umbilical (68%), epigastric (30%), and incisional (2%). Follow-up visits ranged from 8 days to 3.1 years in all but five patients (6%). No hernia recurrences were found in follow-up. Complications included two patients (2.2%) with mesh infection requiring removal of the patch, one patient with post-operative urinary retention, and seroma formation in another patient.

CONCLUSIONS

The composite PTFE/polypropylene hernia patch is effective in preventing hernia recurrence in umbilical, epigastric, and small ventral hernia repairs and can be accomplished with a low rate of complications.

Radiologic gastrostomy

Radiologic gastrostomy has a higher success rate and a lower complication rate and offers a greater choice of tubes than percutaneous endoscopic gastrostomy (PEG). The position and configuration of the stomach and colon are clearly seen under fluoroscopy, and ultrasound can be used to locate the liver. Radiologic gastrostomy procedures can be performed when there are oropharyngeal tumors, or esophageal strictures and stents, and can be performed under local anesthesia alone. Peroral push-gastrostomies are preferable for palliative care and for patients with neurogenic dysphagia, but percutaneously inserted tubes should be used in patients with upper gastrointestinal cancers in order to avoid tumor seeding. Unfortunately, awareness of and access to radiologic techniques are still limited and this has led to the development of "adventurous" techniques for placing endoscopes in stomachs rather than applying simple fluoroscopic alternatives.

Removal of aqueous arsenic using iron attached to immobilized ligands (IMLIGs)

The present study describes the synthesis of the iron(III) salt of a commercially available immobilized ligand, IMLIG, Octolig-21 and its use to remove arsenic from aqueous solutions. The synthesis was accomplished by treating an aqueous suspension of Octolig-21 with an equal weight of ferrous sulfate heptahydrate under nitrogen. The ferrous salt was then collected by sieving and allowed to oxidize to the iron (III) salt by exposure to air, and treatment with dilute sodium hydroxide converted the composite to the hydroxide. Using standard test water containing 300 ppb As and column chromatography, reduction of the arsenic concentration to 3 ppb or less in the effluent was achieved, using a pair of columns (4.5 cm id; 1780 mL and 2019 mL, respectively) in tandem. Subsequently, the Fe(III)-Octolig composite was tested for capacity, and it was calculated that with an input of 50 ppb As, it could take up to a year for the effectiveness to be exhausted.

Single dose oral ranitidine improves MRCP image quality: a double-blind study

AIM

To investigate the possibility of whether a single 300 mg dose of ranitidine given orally 2-3h before magnetic resonance cholangiopancreatography (MRCP) could reduce the signal from the stomach and duodenum, and thus increase the conspicuousness of the biliary tree.

MATERIALS AND METHODS

Thirty-five volunteers (22 female, 13 male), (age range 21-50) were underwent MRCP in a double-blind, placebo-controlled, randomized, crossover trial on a Philips Intera 1.5 T machine using a phased array surface coil. Imaging was carried out in the coronal oblique plane. Six 40 mm sections were acquired at varying angles to delineate the biliary tree and pancreatic duct. The 70 examinations were blindly scored by three consultants experienced in cholangiography.

RESULTS

After ranitidine administration there was a significant decrease in signal from the stomach (mean=17.7, p=0.0005, CI 10, 25.3) and duodenum (mean=18.4, p=0.0005, 95%CI 9.6, 27.1) with a significant increase in conspicuousness of the distal common duct (mean=7.7, p=0.033, 95%CI 0.7, 14.7) and proximal common duct (mean=8.7, p=0.010 CI 2.2, 15.2). There were no adverse effects.

CONCLUSION

Oral ranitidine is a cheap and effective agent to decrease signal from the upper gastrointestinal tract and to improve visibility of the biliary tree.

Troponin T after endoscopic retrograde cholangiopancreatography: no evidence of harm

BACKGROUND AND STUDY AIMS

It is well recognized that myocardial ischemia can occur during endoscopic retrograde cholangiopancreatography (ERCP). Acute arrhythmias and ST segment changes have been reported by a number of authors, but the longer-term sequelae with regard to permanent myocardial damage are not known. The aim of this study was to determine the presence or absence of significant injury to the heart muscle.

PATIENTS AND METHODS

Sixty-two patients undergoing therapeutic ERCP were assessed clinically and with electrocardiography (ECG) for the presence of ischemic heart disease before the procedure. Extensive intraprocedural monitoring was carried out, postprocedural ECGs were recorded, and serum troponin T levels were measured. The ECGs were evaluated blindly by a single cardiologist.

RESULTS

In 61 of the 62 patients, no changes were observed between the ECGs before and after the procedure. One patient had postprocedural T wave inversion but a normal troponin T level, excluding myocardial damage. One patient with mild renal insufficiency and treated heart failure had borderline troponin T elevation (0.05 microg/l) but no ECG changes. No complications of ERCP occurred.

CONCLUSIONS

Whilst ECG and rhythm changes indicating transient myocardial ischemia do occur during ERCP, there is no evidence that myocardial damage takes place as a consequence of this.