Occasionally during the course of a drug's development the levels of drug and potential metab... more Occasionally during the course of a drug's development the levels of drug and potential metabolites in specific tissues must be determined; however, when those tissues are fibrous and small (~100 mg) efficient sample preparation where homogenization and extraction are required often proves to be a difficult task. Previous attempts to utilize standard homogenization and pulverizing techniques to prepare rodent eyes, such as Waring blenders, probe homogenizers and a mortar and pestle, were either inefficient or labor intensive and technically difficult. In each instance the chances for cross-sample contamination were high as was the time and effort spent by the analyzing scientist during multiple sample preparations. Adaptive focused acoustic (AFA) technology has shown promise in enhancing sample recovery in plant and animal-based samples [Toorchi M, Nouri MZ, Tsumura M and Komatsu S. Acoustic Technology for High-Performance Disruption and Extraction of Plant Proteins. J Proteome ...
P. falciparum-infected erythrocytes (IRBC) expressing the domain cassettes (DC) 8 and 13 of the c... more P. falciparum-infected erythrocytes (IRBC) expressing the domain cassettes (DC) 8 and 13 of the cytoadherent ligand PfEMP1 adhere to the endothelial protein C receptor (EPCR). By interfering with EPCR anti-coagulant and pro-endothelial barrier functions, IRBC adhesion could promote coagulation and vascular permeability that contribute to the pathogenesis of cerebral malaria. In this study, we examined adhesion of DC8- and DC13-expressing parasite lines to endothelial cells from different microvasculature, and the consequences of EPCR engagement on endothelial cell function. We found that IRBC from IT4var19 (DC8) and IT4var07 (DC13) parasite lines adhered to human brain, lung, and dermal endothelial cells under shear stress. However, the relative contribution of EPCR to parasite cytoadherence on the different types of endothelial cell varied. We also observed divergent functional outcomes for DC8 CIDRα1.1 and DC13 CIDRα1.4 domains. IT4var07 CIDRα1.4 inhibited generation of activated ...
The American journal of tropical medicine and hygiene, 2005
The cytoadherence of Plasmodium falciparum-infected erythrocytes (IRBCs) to endothelium is mediat... more The cytoadherence of Plasmodium falciparum-infected erythrocytes (IRBCs) to endothelium is mediated by adhesion molecules within the physical constraints of a viscous fluid containing mostly erythrocytes. The volume fraction of erythrocytes (hematocrit) and their physical properties, such as deformability, are important properties of blood that affect cell recruitment to the vascular wall. In the present study, we examined the effect of hematocrit on IRBC rolling and adhesion on human microvascular endothelial cells in a flow chamber system in vitro. We found hematocrit to be a major determinant of IRBC/endothelial cell interactions. There was a 5-fold and 12-fold increase in IRBC rolling and adhesion, respectively, when hematocrit increased from 10% to 30%, as a result of changes in shear rate. Similar effects were seen in the presence of less deformable erythrocytes, serum proteins, and on endothelium stimulated with tumor necrosis factor-alpha. The results indicate that hemorheol...
Burkholderia (Pseudomonas) pseudomallei is the causative agent of melioidosis, a bacterial infect... more Burkholderia (Pseudomonas) pseudomallei is the causative agent of melioidosis, a bacterial infection of considerable morbidity in areas of endemicity of Southeast Asia and northern Australia. Clinical isolates of B. pseudomallei have been demonstrated to produce a lipopolysaccharide (LPS) containing two separate and chemically distinct antigenic O polysaccharides against which infected patients produced antibodies. A putative capsular polysaccharide (CPS) has also been reported and is thought to be antigenically conserved based on results of serological studies with clinical B. pseudomallei isolates. In the present study, the CPS isolated from B. pseudomallei 304b from northeastern Thailand was found to have an [alpha]D of +99 degrees (water), was composed of D-galactose (D-Gal), 3-deoxy-D-manno-2-octulosonic acid (KDO), and O-acetyl 3:1:1), and was a linear unbranched polymer of repeating tetrasaccharide units having the following structure: -3)-2-O-Ac-beta-D-Galp-(1-4)-alpha-D-Gal...
... Permissions & Reprints. The Pathophysiology of Malaria. This article is not included in y... more ... Permissions & Reprints. The Pathophysiology of Malaria. This article is not included in your organization's subscription. However, you may be able to access this article under your organization's agreement with Elsevier. Nicholas J. White a and May Ho b. ...
Pulmonary complication in severe Plas- modium falciparum malaria is manifested as a prolonged imp... more Pulmonary complication in severe Plas- modium falciparum malaria is manifested as a prolonged impairment of gas trans- fer or the more severe acute respiratory distress syndrome (ARDS). In either clini- cal presentation, vascular permeability is a major component of the pathologic pro- cess. In this report, we examined the effect of clinical P falciparum isolates on barrier function of primary
The lipopolysaccharide (LPS) of Burkholderia pseudomallei, the causative agent of melioidosis, co... more The lipopolysaccharide (LPS) of Burkholderia pseudomallei, the causative agent of melioidosis, consists of two O-antigenic polysaccharides designated O-PS I and O-PS II. In this study, the O-PS specificity and functional activity of a protective polyclonal antiserum and an immunoglobulin M (IgM) monoclonal antibody were determined. The polyclonal antiserum recognized both O-PS I and O-PS II, while the monoclonal antibody was O-PS II specific. Both mediated phagocytic killing of B. pseudomallei by polymorphonuclear leukocytes. Patients acutely infected with B. pseudomallei also produced antibodies to the two O-PSs, but these antibodies were not produced by asymptomatic individuals from an area of endemicity who were seropositive by an indirect hemagglutination test using sonicated heat-killed whole organisms as antigen. IgM antibodies were detected only in patients with localized infection. IgG antibodies were detected in all acutely infected patients, but there was no significant di...
The pathogenicity of Plasmodium falcipa- rum is due to the unique ability of infected erythrocyte... more The pathogenicity of Plasmodium falcipa- rum is due to the unique ability of infected erythrocytes (IRBCs) to adhere to vascular endothelium. We investigated whether adhe- sion of IRBCs to CD36, the major cytoadher- ence receptor on human dermal microvascu- lar endothelial cells (HDMECs), induces intracellular signaling and regulates adhe- sion. A recombinant peptide corresponding to the minimal CD36-binding domain from
If the original assumption that the volumes are additive is correct, it is appropriate to express... more If the original assumption that the volumes are additive is correct, it is appropriate to express the optical rotation of the mixture as a function of the volume fraction of each component. This may be represented by the equation ... Thus are derived the three equations needed to ...
This study aimed to investigate the composition of microflora in endodontically treated teeth ass... more This study aimed to investigate the composition of microflora in endodontically treated teeth associated with asymptomatic periapical lesions in southern Chinese patients. Twenty-four teeth which had received nonsurgical root canal treatment more than 4 years previously, and which presents an acceptable coronal restoration with a periapical radiolucent area, were re-treated nonsurgically. Bacteriological samples were obtained after removal of the old root canal filling. The samples were inoculated on enriched trypticase soy agar and four selective media for incubation at 37 degrees C in both a carbon dioxide-enriched atmosphere and anaerobically. Eighteen teeth that had received gutta-percha root canal fillings were grouped for analysis, 12 (66.7%) of which contained cultivable microorganisms. The total colony forming units per ml of transport medium ranged from 0 to 2.3 x 10(5). The number of bacterial genera recovered ranged between 0 and 6, with facultative gram-positive cocci being the most prevalent group of bacteria isolated. Facultative anaerobic bacteria were present in all, whereas strict anaerobic bacteria were found in 3 out of the 12 teeth with positive growth. The size of the periapical rarefaction did not show any relationship with the quantity of microorganisms recovered. Coagulase-negative staphylococci, streptococci and Pseudomonas aeruginosa were most frequently isolated in this group of patients. The possible origin of these organisms is discussed.
Plasmodium-infected erythrocytes lose their normal deformability and become susceptible to spleni... more Plasmodium-infected erythrocytes lose their normal deformability and become susceptible to splenic filtration. In animal models, this is one mechanism of antimalarial defense. To assess the effect of acute falciparum malaria on splenic filtration, we measured the clearance of heated âµÂ¹Cr-labeled autologous erythrocytes in 25 patients with acute falciparum malaria and in 10 uninfected controls. Two groups of patients could be
1. This study assessed the mass balance, metabolism and disposition of [(14)C]trametinib, a first... more 1. This study assessed the mass balance, metabolism and disposition of [(14)C]trametinib, a first-in-class mitogen-activated extracellular signal-related kinase (MEK) inhibitor, as an open-label, single solution dose (2 mg, 2.9 MBq [79 µCi]) in two male subjects with advanced cancer. 2. Trametinib absorption was rapid. Excretion was primarily via feces (∼81% of excreted dose); minor route was urinary (∼19% of excreted dose). The primary metabolic elimination route was deacetylation alone or in combination with hydroxylation. Circulating drug-related component profiles (composed of parent with metabolites) were similar to those found in elimination together with N-glucuronide of deacetylation product. Metabolite analysis was only possible from <50% of administered dose; therefore, percent of excreted dose (defined as fraction of percent of administered dose recovery over total dose recovered in excreta) was used to assess the relative importance of excretion and metabolite routes. The long elimination half-life (∼10 days) favoring sustained targeted activity was important in permitting trametinib to be the first MEK inhibitor with clinical activity in late stage clinical studies. 3. This study exemplifies the challenges and adaptability needed to understand the metabolism and disposition of an anticancer agent, like trametinib, with both low exposure and a long elimination half-life.
1. SB-242235 (1-(4-piperidinyl)-4-(4-fluorophenyl)-5-(2-methoxy-4-pyrimidinyl) imidazole) is a po... more 1. SB-242235 (1-(4-piperidinyl)-4-(4-fluorophenyl)-5-(2-methoxy-4-pyrimidinyl) imidazole) is a potent and selective p38 MAP kinase inhibitor that may be an effective therapy for cytokine-mediated diseases such as autoimmune or inflammatory diseases. The present studies were conducted to evaluate the pharmacokinetics of SB-242235 in several preclinical species, including rat, dog and monkey. 2. SB-242235 demonstrates generally favourable pharmacokinetic properties in all species examined. Systemic plasma clearance was high in rat, but in the non-rodent species SB-242235 demonstrated low to moderate clearance with plasma half-lives > 4h. Oral bioavailability in each preclinical species was high. In rat and monkey, SB-242235 demonstrated non-linear elimination kinetics that manifested as a decrease in clearance with increasing dose and apparent oral bioavailability > 100% at high oral doses. Furthermore, SB-242235 displayed concentration-dependent plasma protein binding over a concentration range of 1000-10,000 ng ml(-1). 3. In conclusion, SB-242235 demonstrates high oral bioavailability across the major preclinical species, and may thus be a useful tool compound for investigation of the role of p38 inhibition in various disease states. However, the observations of non-linear protein binding and disposition also suggest the need for caution in the design of and data interpretation from such studies.
As many as 50% of total hospital admissions are readmissions. Because the factors contributing to... more As many as 50% of total hospital admissions are readmissions. Because the factors contributing to hospital readmission are multiple, and research findings are not conclusive, it is important for clinicians to gain an understanding of the key factors that contribute to readmission. This study explores the factors contributing to hospital readmission and derives an explanatory model that can best identify characteristics of patients at high risk for hospital readmission. This research was a case-controlled study with readmitted patients (n = 168) as the readmitted group and non-readmitted patients (n = 98) as the control group. The variables included demographic data, health assessment data, medical diagnosis, frequency of admissions, severity of illness, intensity of service and improvement of condition. The study sample was also interviewed to explore the patients' views on their repeated hospitalization. In the bivariate analysis significant differences between the study and control groups were multiple and generally consistent with findings in other studies. Using multiple logistic regression, however, the final model shows that only three factors best predict readmissions: frequency (3-4 times) of readmissions (OR = 9.96, p < .0001) and frequency (more than 5 times) of readmissions (OR = 15.73, p < .0001), financial assistance (OR = 5.03, p < .001), and severity of illness (OR = 3.12, p < .01). Our interview data suggest that the readmitted patients required assistance to accomplish daily living activities upon discharge and often returned to the hospital for the same health reason. The study findings suggest that patients who are frequently readmitted to the hospital are severely ill; are on public assistance; and may need special attention when discharged in order to attenuate repeated hospital readmission.
Occasionally during the course of a drug's development the levels of drug and potential metab... more Occasionally during the course of a drug's development the levels of drug and potential metabolites in specific tissues must be determined; however, when those tissues are fibrous and small (~100 mg) efficient sample preparation where homogenization and extraction are required often proves to be a difficult task. Previous attempts to utilize standard homogenization and pulverizing techniques to prepare rodent eyes, such as Waring blenders, probe homogenizers and a mortar and pestle, were either inefficient or labor intensive and technically difficult. In each instance the chances for cross-sample contamination were high as was the time and effort spent by the analyzing scientist during multiple sample preparations. Adaptive focused acoustic (AFA) technology has shown promise in enhancing sample recovery in plant and animal-based samples [Toorchi M, Nouri MZ, Tsumura M and Komatsu S. Acoustic Technology for High-Performance Disruption and Extraction of Plant Proteins. J Proteome ...
P. falciparum-infected erythrocytes (IRBC) expressing the domain cassettes (DC) 8 and 13 of the c... more P. falciparum-infected erythrocytes (IRBC) expressing the domain cassettes (DC) 8 and 13 of the cytoadherent ligand PfEMP1 adhere to the endothelial protein C receptor (EPCR). By interfering with EPCR anti-coagulant and pro-endothelial barrier functions, IRBC adhesion could promote coagulation and vascular permeability that contribute to the pathogenesis of cerebral malaria. In this study, we examined adhesion of DC8- and DC13-expressing parasite lines to endothelial cells from different microvasculature, and the consequences of EPCR engagement on endothelial cell function. We found that IRBC from IT4var19 (DC8) and IT4var07 (DC13) parasite lines adhered to human brain, lung, and dermal endothelial cells under shear stress. However, the relative contribution of EPCR to parasite cytoadherence on the different types of endothelial cell varied. We also observed divergent functional outcomes for DC8 CIDRα1.1 and DC13 CIDRα1.4 domains. IT4var07 CIDRα1.4 inhibited generation of activated ...
The American journal of tropical medicine and hygiene, 2005
The cytoadherence of Plasmodium falciparum-infected erythrocytes (IRBCs) to endothelium is mediat... more The cytoadherence of Plasmodium falciparum-infected erythrocytes (IRBCs) to endothelium is mediated by adhesion molecules within the physical constraints of a viscous fluid containing mostly erythrocytes. The volume fraction of erythrocytes (hematocrit) and their physical properties, such as deformability, are important properties of blood that affect cell recruitment to the vascular wall. In the present study, we examined the effect of hematocrit on IRBC rolling and adhesion on human microvascular endothelial cells in a flow chamber system in vitro. We found hematocrit to be a major determinant of IRBC/endothelial cell interactions. There was a 5-fold and 12-fold increase in IRBC rolling and adhesion, respectively, when hematocrit increased from 10% to 30%, as a result of changes in shear rate. Similar effects were seen in the presence of less deformable erythrocytes, serum proteins, and on endothelium stimulated with tumor necrosis factor-alpha. The results indicate that hemorheol...
Burkholderia (Pseudomonas) pseudomallei is the causative agent of melioidosis, a bacterial infect... more Burkholderia (Pseudomonas) pseudomallei is the causative agent of melioidosis, a bacterial infection of considerable morbidity in areas of endemicity of Southeast Asia and northern Australia. Clinical isolates of B. pseudomallei have been demonstrated to produce a lipopolysaccharide (LPS) containing two separate and chemically distinct antigenic O polysaccharides against which infected patients produced antibodies. A putative capsular polysaccharide (CPS) has also been reported and is thought to be antigenically conserved based on results of serological studies with clinical B. pseudomallei isolates. In the present study, the CPS isolated from B. pseudomallei 304b from northeastern Thailand was found to have an [alpha]D of +99 degrees (water), was composed of D-galactose (D-Gal), 3-deoxy-D-manno-2-octulosonic acid (KDO), and O-acetyl 3:1:1), and was a linear unbranched polymer of repeating tetrasaccharide units having the following structure: -3)-2-O-Ac-beta-D-Galp-(1-4)-alpha-D-Gal...
... Permissions & Reprints. The Pathophysiology of Malaria. This article is not included in y... more ... Permissions & Reprints. The Pathophysiology of Malaria. This article is not included in your organization's subscription. However, you may be able to access this article under your organization's agreement with Elsevier. Nicholas J. White a and May Ho b. ...
Pulmonary complication in severe Plas- modium falciparum malaria is manifested as a prolonged imp... more Pulmonary complication in severe Plas- modium falciparum malaria is manifested as a prolonged impairment of gas trans- fer or the more severe acute respiratory distress syndrome (ARDS). In either clini- cal presentation, vascular permeability is a major component of the pathologic pro- cess. In this report, we examined the effect of clinical P falciparum isolates on barrier function of primary
The lipopolysaccharide (LPS) of Burkholderia pseudomallei, the causative agent of melioidosis, co... more The lipopolysaccharide (LPS) of Burkholderia pseudomallei, the causative agent of melioidosis, consists of two O-antigenic polysaccharides designated O-PS I and O-PS II. In this study, the O-PS specificity and functional activity of a protective polyclonal antiserum and an immunoglobulin M (IgM) monoclonal antibody were determined. The polyclonal antiserum recognized both O-PS I and O-PS II, while the monoclonal antibody was O-PS II specific. Both mediated phagocytic killing of B. pseudomallei by polymorphonuclear leukocytes. Patients acutely infected with B. pseudomallei also produced antibodies to the two O-PSs, but these antibodies were not produced by asymptomatic individuals from an area of endemicity who were seropositive by an indirect hemagglutination test using sonicated heat-killed whole organisms as antigen. IgM antibodies were detected only in patients with localized infection. IgG antibodies were detected in all acutely infected patients, but there was no significant di...
The pathogenicity of Plasmodium falcipa- rum is due to the unique ability of infected erythrocyte... more The pathogenicity of Plasmodium falcipa- rum is due to the unique ability of infected erythrocytes (IRBCs) to adhere to vascular endothelium. We investigated whether adhe- sion of IRBCs to CD36, the major cytoadher- ence receptor on human dermal microvascu- lar endothelial cells (HDMECs), induces intracellular signaling and regulates adhe- sion. A recombinant peptide corresponding to the minimal CD36-binding domain from
If the original assumption that the volumes are additive is correct, it is appropriate to express... more If the original assumption that the volumes are additive is correct, it is appropriate to express the optical rotation of the mixture as a function of the volume fraction of each component. This may be represented by the equation ... Thus are derived the three equations needed to ...
This study aimed to investigate the composition of microflora in endodontically treated teeth ass... more This study aimed to investigate the composition of microflora in endodontically treated teeth associated with asymptomatic periapical lesions in southern Chinese patients. Twenty-four teeth which had received nonsurgical root canal treatment more than 4 years previously, and which presents an acceptable coronal restoration with a periapical radiolucent area, were re-treated nonsurgically. Bacteriological samples were obtained after removal of the old root canal filling. The samples were inoculated on enriched trypticase soy agar and four selective media for incubation at 37 degrees C in both a carbon dioxide-enriched atmosphere and anaerobically. Eighteen teeth that had received gutta-percha root canal fillings were grouped for analysis, 12 (66.7%) of which contained cultivable microorganisms. The total colony forming units per ml of transport medium ranged from 0 to 2.3 x 10(5). The number of bacterial genera recovered ranged between 0 and 6, with facultative gram-positive cocci being the most prevalent group of bacteria isolated. Facultative anaerobic bacteria were present in all, whereas strict anaerobic bacteria were found in 3 out of the 12 teeth with positive growth. The size of the periapical rarefaction did not show any relationship with the quantity of microorganisms recovered. Coagulase-negative staphylococci, streptococci and Pseudomonas aeruginosa were most frequently isolated in this group of patients. The possible origin of these organisms is discussed.
Plasmodium-infected erythrocytes lose their normal deformability and become susceptible to spleni... more Plasmodium-infected erythrocytes lose their normal deformability and become susceptible to splenic filtration. In animal models, this is one mechanism of antimalarial defense. To assess the effect of acute falciparum malaria on splenic filtration, we measured the clearance of heated âµÂ¹Cr-labeled autologous erythrocytes in 25 patients with acute falciparum malaria and in 10 uninfected controls. Two groups of patients could be
1. This study assessed the mass balance, metabolism and disposition of [(14)C]trametinib, a first... more 1. This study assessed the mass balance, metabolism and disposition of [(14)C]trametinib, a first-in-class mitogen-activated extracellular signal-related kinase (MEK) inhibitor, as an open-label, single solution dose (2 mg, 2.9 MBq [79 µCi]) in two male subjects with advanced cancer. 2. Trametinib absorption was rapid. Excretion was primarily via feces (∼81% of excreted dose); minor route was urinary (∼19% of excreted dose). The primary metabolic elimination route was deacetylation alone or in combination with hydroxylation. Circulating drug-related component profiles (composed of parent with metabolites) were similar to those found in elimination together with N-glucuronide of deacetylation product. Metabolite analysis was only possible from <50% of administered dose; therefore, percent of excreted dose (defined as fraction of percent of administered dose recovery over total dose recovered in excreta) was used to assess the relative importance of excretion and metabolite routes. The long elimination half-life (∼10 days) favoring sustained targeted activity was important in permitting trametinib to be the first MEK inhibitor with clinical activity in late stage clinical studies. 3. This study exemplifies the challenges and adaptability needed to understand the metabolism and disposition of an anticancer agent, like trametinib, with both low exposure and a long elimination half-life.
1. SB-242235 (1-(4-piperidinyl)-4-(4-fluorophenyl)-5-(2-methoxy-4-pyrimidinyl) imidazole) is a po... more 1. SB-242235 (1-(4-piperidinyl)-4-(4-fluorophenyl)-5-(2-methoxy-4-pyrimidinyl) imidazole) is a potent and selective p38 MAP kinase inhibitor that may be an effective therapy for cytokine-mediated diseases such as autoimmune or inflammatory diseases. The present studies were conducted to evaluate the pharmacokinetics of SB-242235 in several preclinical species, including rat, dog and monkey. 2. SB-242235 demonstrates generally favourable pharmacokinetic properties in all species examined. Systemic plasma clearance was high in rat, but in the non-rodent species SB-242235 demonstrated low to moderate clearance with plasma half-lives > 4h. Oral bioavailability in each preclinical species was high. In rat and monkey, SB-242235 demonstrated non-linear elimination kinetics that manifested as a decrease in clearance with increasing dose and apparent oral bioavailability > 100% at high oral doses. Furthermore, SB-242235 displayed concentration-dependent plasma protein binding over a concentration range of 1000-10,000 ng ml(-1). 3. In conclusion, SB-242235 demonstrates high oral bioavailability across the major preclinical species, and may thus be a useful tool compound for investigation of the role of p38 inhibition in various disease states. However, the observations of non-linear protein binding and disposition also suggest the need for caution in the design of and data interpretation from such studies.
As many as 50% of total hospital admissions are readmissions. Because the factors contributing to... more As many as 50% of total hospital admissions are readmissions. Because the factors contributing to hospital readmission are multiple, and research findings are not conclusive, it is important for clinicians to gain an understanding of the key factors that contribute to readmission. This study explores the factors contributing to hospital readmission and derives an explanatory model that can best identify characteristics of patients at high risk for hospital readmission. This research was a case-controlled study with readmitted patients (n = 168) as the readmitted group and non-readmitted patients (n = 98) as the control group. The variables included demographic data, health assessment data, medical diagnosis, frequency of admissions, severity of illness, intensity of service and improvement of condition. The study sample was also interviewed to explore the patients' views on their repeated hospitalization. In the bivariate analysis significant differences between the study and control groups were multiple and generally consistent with findings in other studies. Using multiple logistic regression, however, the final model shows that only three factors best predict readmissions: frequency (3-4 times) of readmissions (OR = 9.96, p < .0001) and frequency (more than 5 times) of readmissions (OR = 15.73, p < .0001), financial assistance (OR = 5.03, p < .001), and severity of illness (OR = 3.12, p < .01). Our interview data suggest that the readmitted patients required assistance to accomplish daily living activities upon discharge and often returned to the hospital for the same health reason. The study findings suggest that patients who are frequently readmitted to the hospital are severely ill; are on public assistance; and may need special attention when discharged in order to attenuate repeated hospital readmission.
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