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K Hanna

Publications and source records attributed to K Hanna.

At least 19 recordsLinked to original sources

Assessment of the multi-compound non-equilibrium dissolution behaviour of a coal tar containing PAHs and phenols into water.

Herein, an experimental study coupled with a model in order to assess the non-equilibrium and multi-compound dissolution behaviour of a coal tar containing PAHs and phenols into water, is presented. For this aim, two experimental studies has been carried out: (1) coal tar-water partition equilibrium and (2) dissolution dynamics of coal tar under controlled hydrodynamic conditions in percolation columns packed with glass beads. The dissolution amount of the three target constituents (i.e. phenol, naphthalene and phenanthrene) was monitored by UV detection. The dissolution behaviour was modelled using a predictive fraction approach. The partition coefficients have been estimated from experimental data and the obtained results show that the partition coefficient of each constituent between the aqueous phase and the tar depends on the activities of the constituent in both phases and cannot be estimated only from the solubility of the pure compound in water. The non-equilibrium dissolution model was established, applied for the experimental conditions and validated for three target compounds adjusting the effective interfacial area between tar and water. This parameter is specific of the experimental set-up. The global behaviour of coal tar has been modelled taking into account four categories of compounds according to their water solubility and volatilities. The mass transfer parameters have been estimated using available correlations. The results of this paper indicate that a model based on component fractions can be used to assess the non-equilibrium dissolution behaviour of a coal tar.

Coal Tar↗

Degradation of pentachlorophenol in cyclodextrin extraction effluent using a photocatalytic process.

This work evaluates a process for the elimination of pentachlorophenol (PCP) from effluents provided by a cyclodextrin-assisted flushing of contaminated soils. The effectiveness of photocatalytic degradation of PCP in several cyclodextrin (CD) solutions was evaluated using TiO2 as a photocatalyst. Effects of CD type on PCP degradation rate were studied at two pH values. A similar effect was observed for all CDs used on degradation rate of PCP and the decay of PCP was found to be less extensive at pH 11 than at pH 7. The kinetic orders of the photocatalytic reactions of PCP for all of the solutions have been determined. The first-order rate constants were found to be 0.0884, 0.0362, 0.0197 and 0.0053 min(-1) in CD solutions, respectively, at 0, 1, 2 and 5 mmol l(-1) of CD. Batch experiments were performed in order to study the CD extraction enhancement of PCP previously adsorbed on soil. The results show that the removal capacity of PCP from soil increases with CD concentration (from 0 to 5 mmol l(-1)). When the CD concentration was 5 mmol l(-1), an extraction of about 70% of PCP adsorbed on soil was observed, whereas only 37% was removed when water was used as the flushing solution. The optimal conditions for such a coupled method depend on the nature and concentration of the extracting agent and also on the photocatalytic experimental conditions. This work revealed that the coupling of cyclodextrin-enhanced solubilization and photocatalytic treatment is a promising method for contaminated soil remediation.

2-Hydroxypropyl-beta-cyclodextrin↗

Enhanced solubilization and removal of naphthalene and phenanthrene by cyclodextrins from two contaminated soils.

The development of innovative methods for cleaning contaminated soils has emerged as a significant environmental priority. Herein, are investigated the effectiveness of cyclodextrin (CD) to solubilize and to extract organic pollutants from soils. The interactions in the cyclodextrin/pollutant/soil system have been studied "step by step" using two kinds of polycyclic aromatic hydrocarbons (PAH), naphthalene (Nap) and phenanthrene (Phe), cyclodextrins and soils. Inclusion complex formation of PAH with beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HPCD) has been investigated and was proposed as a way to facilitate the pollutant removal from soil. Little effect of ionic strength was observed on CD complex formation for both compounds. The solubility of PAH in 50 g L(-1) of HPCD was enhanced 20- and 90-fold for naphthalene and phenanthrene, respectively. Batch experiments were performed to study the adsorption-desorption of two PAH on two soils and the influence of CDs over these processes. These experiments were also conducted with a mixture of two PAH. The batch desorption results indicate that removal capacity of HPCD was higher than that of beta-CD. Phenanthrene was strongly sorbed on soils, this led to low desorption rates compared to that of naphthalene, whatever the extracting agent used. When HPCD solution was used as a flushing agent, 80% of naphthalene and 64% of phenanthrene recovery from soil were observed. For both compounds, the slowest desorption rate was found for the soil that had the greatest content of organic matter. CD sorption on soils, was relatively low and depended on soil type. The soil organic matter (SOM) could favor the retention of both CD and pollutant involving the extraction rate to be decreased. A competitive hydrophobic interactions of pollutant between SOM and CD molecules, and co-sorption were expected to be the mechanism for the inhibited desorption.

Adsorption↗

Enhanced solubilization of arsenic and 2,3,4,6 tetrachlorophenol from soils by a cyclodextrin derivative.

The application of extracting aqueous solutions with cyclodextrins in several soil remediation technologies has been increasingly studied but little is known about their removal capacities toward the inorganic species. Herein, the effectiveness of cyclodextrins (CDs) in extracting arsenic, copper, and iron from a mining soil is presented. In a preliminary test of four types of CD aqueous solutions, only the addition of carboxylmethyl-beta-cyclodextrin CMCD (a cyclodextrin derivative) led to a significant enhancement in arsenic removal. An increase in the concentration of copper and iron in the leachates was also observed with CMCD. Kinetic study of arsenic release was carried out at two temperatures (20 and 35 degrees C). The arsenic concentration in the leachates increases with increasing cyclodextrin concentration. At an 80 mM CMCD concentration, arsenic, copper, and iron released in filtrates were about 20-, 1,000-, and 4,000-fold greater, respectively, than that obtained using deionized water. In the soil system, the CMCD capacity removal was found to be higher for cations than for arsenic. Because the tetrachlorophenol can co-occur with arsenic and copper in several contaminated sites, its solubilization by CMCD was also investigated. Extraction experiments were performed to extract 2,3,4,6 tetrachlorophenol (TeCP) in spiked soil with CMCD. The results of batch experiments have shown that CMCD could significantly increase the TeCP extraction from soil. CD sorption on soils as quantified by a fluorescence technique was low, indicating no significant loss of CD during the leaching experiments. The use of CMCD as a flushing agent to enhance the removal of both inorganic and organic pollutants from mixed-contaminated soils appears as a promising remediation method.

Arsenic↗

Cyclodextrin-enhanced solubilization of pentachlorophenol in water.

The solubilization of pentachlorophenol (PCP) by beta-cyclodextrin (beta-CD) and three of its most used derivatives, methyl-beta-cyclodextrin (MCD), hydroxypropyl-beta-cyclodextrin (HPCD) and carboxymethyl-beta-cyclodextrin (CMCD), has been investigated. The formation of soluble inclusion complexes between PCP and cyclodextrin (CDs) increases the aqueous solubility of PCP. Due to the ionizable nature of PCP, the effects of pH and ionic strength on the equilibrium complexation were evaluated. All CDs were found to form 1:1 inclusion complexes. Equilibrium constants calculated from solubility enhancement experiments revealed that the stability of the complexes was dependent on the polarity of the compound, on the ionic strength and on the cyclodextrin type. In general, weaker equilibrium constants were observed for PCP with beta-CD than with MCD or CMCD. For all CDs, the complexation or the solubilization efficiency of PCP (weak acid) depended on pH and ionic strength. Moreover, we observed that the solubility of the beta-CD/PCP complex was lower than that of the beta-CD molecule and dependent on the ionic strength of the solution. Although the equilibrium constant of PCP/CD complex was found to be higher at pH 3 than at pH 7 in water, extraction of PCP from porous media by a CD solution at neutral pH would be achievable due to the higher PCP aqueous solubility in neutral/basic media.

Cyclodextrins↗

Effect of n-alkyl chain length on the complexation of phenanthrene and 9-alkyl-phenanthrene with beta-cyclodextrin.

The characteristics of host-guest complexation between beta-cyclodextrin (beta-CD) and phenanthrene derivatives (phenanthrene, n-propyl, n-butyl and n-hexyl-phenanthrene) were investigated by fluorescence spectrometry. Linear and non-linear regression methods were used to estimate the formation constants (K1). A 1:1 stoichiometric ratio and an effect of n-alkyl chain length on the formation constant were observed for the binary inclusion complex between guest and beta-CD. The formation constant dramatically increases with the length of n-alkyl, it starts from the value of 140 l mol(-1) for the phenanthrene to reach the value of 580 l mol(-1) for hexyl-phenanthrene. The effect of the temperature on the fluorescence intensity of each complex (guest-host) was also studied; and then the thermodynamic parameters were calculated. The main inclusion site seems to be aromatic moiety for short chain molecules, and it moves toward the alkyl chain part, as the chain becomes longer.

Macromolecular Substances↗

Solubilization of the neutral and charged forms of 2,4,6-trichlorophenol by beta-cyclodextrin, methyl-beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin in water.

The solubilities of the neutral and charged forms of 2,4,6-trichlorophenol (TCP) in beta-cyclodextrin (beta-CD) and two of its most used derivatives: methyl-beta-cyclodextrin (MCD) and hydroxypropyl-beta-cyclodextrin (HPCD) solutions were investigated. The three cyclodextrins were found to form 1:1 inclusion complexes. Binding constants estimated from an enhancement solubility method revealed that the stability of the complexes was dependent on the polarity of the compound and on the cyclodextrin used.In general, weaker binding constants were observed for TCP with beta-CD than with HPCD or MCD. The solubilization efficiencies towards TCP can be ranked in the following order: MCD > HPCD > beta-CD. For all cyclodextrins, the stability constant of neutral TCP (logK(ow)=3.85) was larger than that of charged TCP (logK(ow)=1.4).A precipitation occurred in TCP/beta-CD solution (around 10 g/l beta-CD concentration) at pH 3. However, this phenomenon is not observed for TCP/beta-CD solution at pH 8.8.

2-Hydroxypropyl-beta-cyclodextrin↗

Sorption of hydrophobic molecules by organic/inorganic mesostructures.

During the synthesis of micelle-templated silica an intermediate inorganic/organic mesostructure is obtained with an hexagonal arrangement of channels filled by surfactant molecules. The ability of such a mesostructure to solubilize organic molecules from an aqueous solution was investigated. To that end, silica/cationic surfactant mesostructures were prepared under various conditions and their stability toward surfactant release in water was first compared in order to select materials as stable as possible. Swelled mesostructures were also used. The sorption from solution of hydrophobic molecules was then studied. The affinity of the molecules for the mesostructures is directly related to their hydrophobic character as it is derived from their octanol/water partition coefficient. A cooperative effect between hydrophobic molecules and the cationic surfactant that stabilizes the surfactant inside the mesostructure was observed. Interaction energies between the solutes and the mesostructures were determined by microcalorimetry. They varied in accordance with the hydrophobic character of the molecule and, at low sorption amounts, they were of the same order of magnitude as the solubilization enthalpies in bulk micelles. When the sorption increases, the surfactant layer in the mesostructure is not allowed to swell as the free micelle does, and steric limitations in the headgroup area render sorption less favorable.

Journal Article↗

Cerivastatin versus branded pravastatin in the treatment of primary hypercholesterolemia in primary care practice in Canada: a one-year, open-label, randomized, comparative study of efficacy, safety, and cost-effectiveness.

BACKGROUND: Potential cost differences between statins are driven primarily by drug costs, differential lowering effects on low-density lipoprotein cholesterol (LDL-C) levels, and adverse drug interactions and reactions. OBJECTIVE: The purpose of this study was to compare the efficacy, safety, and direct treatment costs of cerivastatin and branded pravastatin in adult patients with primary hypercholesterolemia over a 1-year period. METHODS: This was a multicenter (48 sites), randomized, open-label, parallel-group, optional dose-titration study conducted in Canada. Patients aged 18 to 75 years with documented primary hypercholesterolemia (mean LDL-C > or = 160 mg/dL [> or = 4.5 mmol/L] and at least 1 fasting triglyceride measurement < or = 400 mg/dL [< or = 4.5 mmol/L]) that did not respond adequately to dietary intervention were enrolled. Patients who were on a diet at study entry were instructed to continue that diet for the duration of the study. Patients not following a diet were also entered into the study provided they had received previous dietary counseling and were unwilling or unable to comply with this dietary advice. Before randomization, treating physicians were required to record a target lipid level for each patient and then instructed to randomize patients to treatment with any dose and any titration schedule of cerivastatin or branded pravastatin according to their normal practice. Physicians were not required to titrate the study drug dose if the patient did not achieve the predefined target goal. Lipid analyses were conducted at baseline/randomization and at months 3, 6, 9, and 12. All samples drawn for lipid analyses were collected after a fast of > or = 10 hours. A cost-minimization approach was used to compare the direct treatment costs between cerivastatin and branded pravastatin. Since the analysis was from the perspective of the third-party payer (Ministries of Health), only costs attributed to the third-party payer were included. RESULTS: A total of 417 patients were randomized to once-daily treatment with cerivastatin 0.1 mg to 0.4 mg (n = 209) or branded pravastatin 10 mg to 40 mg (n = 208); 39 (9.4%) of patients discontinued prematurely, 19 (4.6%) because of an adverse event. The incidence of adverse events was similar for cerivastatin (73.6%) and branded pravastatin (74.9%). The majority of adverse events were mild or moderate and included headache, nausea, pain, and dizziness. Both cerivastatin and pravastatin were effective in lowering LDL-C to target levels (mean reduction 29.8% and 27.5%, respectively, P = 0.35). An LDL-C decrease of > or = 20% from baseline to end point was achieved in 74.2% of cerivastatin patients and 74.0% of pravastatin patients. The annualized direct hyperlipidemia treatment cost was 19% higher in the branded pravastatin group compared with the cerivastatin group. A sensitivity analysis designed to examine the impact of generic pricing on the cost-minimization analysis indicated that the cost difference between cerivastatin and generic pravastatin was not significant. CONCLUSIONS: Both cerivastatin and branded pravastatin were well tolerated and effective in lowering LDL-C by > or = 20% versus baseline. A cost savings in favor of cerivastatin was a reflection of the lower drug acquisition cost of cerivastatin compared with branded pravastatin.

Adolescent↗

Reduction in corneal haze and apoptosis by amniotic membrane matrix in excimer laser photoablation in rabbits.

PURPOSE: To determine whether preserved human amniotic membrane can reduce corneal haze and keratocyte apoptosis induced by excimer laser photoablation in rabbit corneas. METHODS: Excimer photoablation was performed bilaterally in 30 rabbits with a 6.0 mm ablation zone and 120 microm depth using the VISX Star laser with the phototherapeutic keratectomy (PTK) mode. One eye was randomly covered by preserved human amniotic membrane secured with 4 interrupted 10-0 nylon sutures, and the other eye served as the control. The amniotic membranes were removed at 1 week, and corneal haze was graded with slitlamp biomicroscopy by 3 masked corneal specialists biweekly for the ensuing 12 weeks until the rabbits were killed. Another 18 rabbits were divided into 4 subgroups and received PTK alone, PTK with membrane, PTK with sham sutures, or PTK with tarsorrhaphy. All eyes were studied histologically, and 3 eyes in each group were studied by in situ terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling assay at 1, 3, and 7 days and 12 weeks, respectively. RESULTS: A consistent grading of differences in corneal haze scoring between the control corneas and the amniotic-membrane-covered corneas was noted among the 3 masked observers. Organized reticular post-PTK corneal haze peaked at 7 weeks in both groups, and the corneal haze score in the amniotic-membrane-covered group was significantly less than in the control group from 7 to 12 weeks (all P < .001). Compared to the control corneas, the amniotic-membrane-covered corneas had less inflammatory response at 1 and 3 days, less keratocyte apoptosis in the ablated anterior corneal stroma at 1, 3, and 7 days (P < .001), and less stromal fibroblast cellularity and epithelial hyperplasia at 12 weeks. CONCLUSIONS: Amniotic membrane matrix introduced at an early stage of the corneal wound healing process effectively reduced corneal haze induced by excimer laser photoablation in rabbits. Studies linking suppression of apoptosis in the acute wound-healing process with reduction of subsequent corneal scarring may have useful clinical applications.

Amnion↗

HIV/AIDS and the risk of deep vein thrombosis: a study of 45 patients with lower extremity involvement.

Many aspects of acquired immunodeficiency syndrome (AIDS) have been described in detail in the literature. However, there have been very few articles on the phenomenon of deep vein thrombosis (DVT) in the lower extremities of human immunodeficiency virus (HIV)/AIDS patients. The objective of this communication is to record the incidence of DVT in HIV/AIDS patients and the risks for development of embolic events and to emphasize the need for prevention and for the vigorous treatment of this complication. We conducted a retrospective review of HIV/AIDS-infected patients with DVT admitted to Mount Sinai School of Medicine/Cabrini Hospital in New York during the last 5 years. Analysis includes demographic data; risk factors for HIV/AIDS infection; associated medical problems; recent surgery; and laboratory findings including CD4 counts, platelet counts, prothrombin times, partial thromboplastin times, and plasma albumin levels; and image studies. From January 1995 to January 2000 4752 HIV/AIDS-infected patients were admitted. Of those admitted to the hospital 45 (0.95%) were found to have DVT. There were 36 males and nine females (mean age 43 years). Of the 45 patients 38 had infectious complications and 13 developed a malignancy. The distribution of the thromboses were the femoral vein in 23 patients, the popliteal vein in 20 patients, and the iliofemoral system in 2 patients. Twelve patients had recurrent DVT and three patients developed a pulmonary embolism. HIV/AIDS infection is a considerable risk for development of DVT in the lower extremity. Statistically DVT in HIV/AIDS is approximately 10 times greater than in the general population. Emphasis upon prevention and vigorous treatment of DVT is recommended.

AIDS-Related Opportunistic Infections↗

Predictive factors associated with axillary lymph node metastases in T1a and T1b breast carcinomas: analysis in more than 900 patients.

BACKGROUND: Axillary lymph node metastasis (ALNM) represents the single most important prognostic indicator in patients diagnosed with breast cancer. The proportion of < or = 1-cm (T1a, T1b) invasive breast carcinomas is increasing. The incidence and predictive factors associated with ALNM in patients with < or = 1-cm tumors remains unclear and the role of axillary lymph node dissection in these patients has been questioned. The purpose of this study was to determine clinical and pathologic factors predictive of ALNM in patients with < or = 1-cm invasive breast carcinomas by univariate and multivariate analyses. STUDY DESIGN: Review analysis from a prospective database identified patients with < or = 1-cm invasive breast cancers treated at our institution between 1990 and 1996. All patients underwent a resection of the primary tumor and axillary lymph node dissections. Routine patient and tumor characteristics evaluated included: age, race, tumor size, histologic grade, estrogen and progesterone receptor status, and lymphatic and vascular invasion. Univariate and multivariate analyses were performed. Adjusted odds ratios (OR) and 95% confidence intervals (CI) are presented. RESULTS: A total of 919 patients were identified in this study with tumors < or = 1 cm. These included 199 patients (21.7%) with T1a tumors and 720 patients (78.3%) with T1b tumors. ALNM was detected in 165 patients with an overall incidence of 18.0%. Of the ALNM group, 32 patients (19.4%) had T1a tumors and 133 patients (80.6%) had T1b tumors. Four variables were found to be significant in univariate analysis. These included: increasing tumor size, poor histologic grade, presence of lymphatic or vascular invasion, and younger age of the patient. An increase in tumor size was associated with a significant risk of ALNM (OR = 2.66, 95% CI = 1.28 to 5.75; p = 0.01). Poor tumor grade and the presence of lymphatic or vascular invasion were also associated with an increased risk of ALNM (OR = 2.69, p = 0.003 and OR = 5.52, p = 0.0001, respectively). Patients with ALNM were more likely to have a tumor grade of 3 (25.0% ALNM versus 12.5% node-negative, p = 0.004) and lymphatic or vascular invasion (16.9% ALNM versus 3.5% node-negative, p < 0.0001). In multivariate analysis, an increased risk of ALNM was demonstrated with increasing tumor size (0.1-cm increments), poor histologic grade, and younger age. CONCLUSIONS: This study investigated clinical and pathologic factors influencing ALNM in patients with T1a and T1b breast carcinomas. We have identified three factors by multivariate analysis as significant independent predictors of ALNM in this group of patients. These include increasing tumor size, poor histologic grade, and younger age. Given the significant amount of ALNM demonstrated in this study (overall 18%) and the inability to identify a subgroup of patients that had an acceptable low risk of ALNM, the complete omission of assessing the axilla for metastatic disease in patients with small breast cancers cannot be advocated. Our recommendation for patients diagnosed with T1a and T1b tumors is to have their axilla investigated for metastatic disease either by traditional axillary lymph node dissections or by intraoperative lymphatic mapping and sentinel lymph node biopsy techniques.

Adult↗

Changes in liver function tests after laparoscopic cholecystectomy: not so rare, not always ominous.

The incidental findings of increased alanine aminotransferase (ALT) and aspartate amino transferase (AST) after uneventful laparoscopic cholecystectomy (LC) prompted us to investigate the incidence and the clinical significance of this phenomenon. Changes in liver function test after LC (n = 55) were compared with those after OC (n = 16). Liver function tests were obtained preoperatively and postoperatively on days 1, 2, and 7. All of the patients fulfilled the selection criteria: normal preoperative liver function test and no endoscopic retrograde cholangiopancreatography, common bile duct exploration, or postoperative biliary complications (injury, infection, or obstruction). Converted cholecystectomies were also excluded. During LC, the intra-abdominal pressure was maintained within the conventional range of 14 to 15 mm Hg. ALT had doubled in the first 48 hours from the preoperative mean in 58.2 per cent in LC patients versus only 6.3 per cent in the OC group. AST doubled from the preoperative mean value in 38.2 per cent in the LC group versus only 6.3 per cent in the OC group. By the 7th postoperative day, the enzymes returned to the preoperative values in both the LC and the OC group. In many instances, a significant increase in ALT and AST blood levels occurred after uneventful LC. The phenomenon is transient as these enzymes returned to normal value within 7 days. These changes are clinically silent in patients with a normal liver function.

Adult↗

Efficacy and safety of cerivastatin in primary hypercholesterolemia: a long term comparative titration study with simvastatin.

OBJECTIVE: To compare cerivastatin with simvastatin in their long term safety and efficacy in reducing low density lipoprotein cholesterol (LDL-C). DESIGN: Multicentre, randomized, double-blind, parallel group study. SETTING: Thirteen Canadian centres. PATIENTS AND METHODS: A total of 387 patients with primary hypercholesterolemia received treatment with either cerivastatin (0. 05 to 0.3 mg/day) or simvastatin (5 to 40 mg/day) to achieve plasma LDL-C levels below 3.36 mmol/L (130 mg/dL) for an initial 32-week dose-titration phase and a subsequent 72-week extension phase. MAIN RESULTS: Cerivastatin and simvastatin produced clinically significant reductions in LDL-C of 28.4% and 35.4%, respectively, at the end point for the 32-week study, and reductions of 32.8% and 35. 0%, respectively, at the end of the extension phase of the study. Response rates (a greater than 15% drop in LDL-C) were comparable for the two treatments (88.9% cerivastatin versus 93.2% simvastatin) at the 32-week end point. Response rates were 100% for both treatments at the end of the 72-week extension phase. Both treatments also reduced total cholesterol, apolipoprotein B and very low density lipoprotein cholesterol levels. Cerivastatin and simvastatin increased HDL-C levels significantly by 8.8% and 11.0%, respectively, at the end point for the 32-week study, and by 8.6% and 12.1%, respectively, at the end of the extension phase of the study. Treatments were well tolerated, and the incidence of adverse effects was similar in both groups. CONCLUSIONS: This forced titration study demonstrates that cerivastatin, given once daily at doses up to 0.3 mg/day, is effective and well tolerated. The results of this study support further investigation of higher doses of cerivastatin given the excellent safety profile at doses up to 0.3 mg.

Anticholesteremic Agents↗

Laparoscopic appendectomy in children.

Laparoscopic appendectomy is a common surgery in most pediatric surgical centers. Many studies, mostly retrospective reviews in adults, show the advantages of the laparoscopic approach to be less wound infections, shortened postoperative recovery, and faster return to normal activities. In addition, less analgesic medication is required postoperatively. Potential disadvantages of laparoscopic appendectomy include an increased operative time, elevated costs when disposable instruments are used, and possibly more infectious complications when performed for complicated appendicitis. There are no prospective, randomized trials comparing laparoscopic versus open appendectomy in children. Until these studies are completed, questions will persist regarding the benefits of laparoscopic appendectomy in children.

Adult↗