An increasing body of research implicates inflammatory processes, including alterations in the ne... more An increasing body of research implicates inflammatory processes, including alterations in the neutrophil-lymphocyte ratio (NLR), in the pathophysiology of psychiatric illness. The deer mouse (Peromyscus maniculatus bairdii) is commonly studied for its naturalistic expression of compulsive-like behaviour. Towards future efforts to gain an understanding of how innate and adaptive immune processes might be involved this model, we set out to study the effects of pegfilgrastim, a pegylated recombinant human granulocyte colony-stimulating factor (g-CSF) analogue, on the NLR of both male and female deer mice. Briefly, 54 deer mice (equally distributed between sexes) were exposed to a single injection with either control or pegfilgrastim (0.1 or 1 mg/kg) (n = 18 per group). Six mice of each group were euthanized on days two, four and seven post-administration, blood collected and the NLR calculated. Our results showed that irrespective of dose, pegfilgrastim resulted in higher NLR values i...
Sinusitis, more aptly referred to as rhinosinusitis, can be described as a symptomatic inflammato... more Sinusitis, more aptly referred to as rhinosinusitis, can be described as a symptomatic inflammatory condition of the paranasal sinuses and the nasal cavity. 1 Generally, the condition is regarded as acute (ARS) if lasting up to 4 weeks, sub-acute when lasting between 4 and 12 weeks, and chronic (CRS) if symptoms present for more than 12 weeks. 2
Osteoporosis is a highly prevalent and debilitating condition that contributes to the risk of fra... more Osteoporosis is a highly prevalent and debilitating condition that contributes to the risk of fracture in both women and men. The current paper will provide a rapid clinical overview of the condition and the current pharmacotherapeutic approaches applied in its treatment. We close with a summary of novel treatment strategies currently being developed and explain the role of sequential combination therapy in the management of established osteoporosis.
Rheumatoid arthritis, an auto-immune disorder, is characterized by chronic inflammation of the jo... more Rheumatoid arthritis, an auto-immune disorder, is characterized by chronic inflammation of the joints, synovial hyperplasia and bone erosion. These pathological features are promoted by a synovial microenvironment featuring B-cell and T-cell infiltrate, synovial fibroblasts and an intricate network of pro-inflammatory cellular messengers – prominent molecular role-players that represent critical targets in the pharmacotherapy of the disease. This review offers a brief overview of the etiopathology of rheumatoid arthritis while focussing on the practical aspects of methotrexate and glucocorticoid use that are of relevance for primary practice.
Pre-exposure prophylaxis (PrEP) refers to the use of antiretroviral drugs to prevent one from acq... more Pre-exposure prophylaxis (PrEP) refers to the use of antiretroviral drugs to prevent one from acquiring human immunodeficiency virus (HIV) infection when engaging in high-risk sexual behaviour. Adequate PrEP initiation is key in the clinical outcome and survival of not only vulnerable and high-risk populations, but also to ensure that a society which is free of HIV, is built.
Type 2 diabetes mellitus (T2DM), previously regarded as being a disease borne exclusively from fo... more Type 2 diabetes mellitus (T2DM), previously regarded as being a disease borne exclusively from following a poor lifestyle, affects at least 415 million individuals worldwide, a number which is believed will increase to 640 million by 2040. As our understanding of T2DM improved over time, it became clear that the condition is underpinned by interactions between poor lifestyle choices and highly varying genetic constructs that involve more than 400 genes. Although a comprehensive review of the genetic architecture of T2DM falls beyond the scope of the current paper, it suffices to say that failure to regard the pathophysiology of T2DM and its subsequent treatment from a drastically different perspective, will result in an increasing burden of the condition on society. This is especially realistic, since despite the fact that oral hypoglycaemic drugs have been used since 1955, current approaches fail to arrest the continuous global rise in the number of T2DM cases.
Please help us populate SUNScholar with the post print version of this article. It can be e-maile... more Please help us populate SUNScholar with the post print version of this article. It can be e-mailed to: scholar@sun.ac.zaGeneeskundePsigiatri
Objective: Depression is suggested to involve disturbances in cholinergic as well as glutamatergi... more Objective: Depression is suggested to involve disturbances in cholinergic as well as glutamatergic pathways, particularly the N-methyl-d-aspartate receptor-mediated release of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP). The aim of this study was to determine whether the Flinders Sensitive Line (FSL) rat, a genetic model of depression, presents with corticolimbic changes in basal acetylcholine (ACh) levels and NO/cGMP signalling. Methods: Basal levels of nitrogen oxides (NOx) and both basal and l-arginine-stimulated nitric oxide synthase (NOS) formation of l-citrulline were analysed in hippocampus and frontal cortex in FSL and control Flinders resistant line (FRL) rats by fluorometric and electrochemical high-performance liquid chromatography, respectively. In addition, ACh and cGMP levels were analysed by liquid chromatography tandem mass spectrometry and radioimmunoassay, respectively. Results: Significantly elevated frontal cortical but reduced hippocampal ACh lev...
Therapeutic drug monitoring (TDM) fulfils an important function in patient health in both the pub... more Therapeutic drug monitoring (TDM) fulfils an important function in patient health in both the public and private healthcare systems. TDM is based on pharmacokinetic principles within the clinical laboratory and several health professionals, from different disciplines, take part in the management and implementation of the whole TDM process. Communication and collaboration between these professionals are extremely important to ensure beneficial TDM and patient care, however, human error plays a major role in the compromising of the TDM process. In this article, we discuss the most common human errors during the TDM process and give guidelines to prevent them. These guidelines must be implemented during all the TDM phases to ensure the patient receives optimal and reliable healthcare.
Overweight and obesity are not only two highly prevalent conditions in the South African society,... more Overweight and obesity are not only two highly prevalent conditions in the South African society, but they also contribute to 6 of the 10 most common causes of death. Further, being overweight not only results in significant metabolic and endocrine disturbances, it also changes how patients respond to most pharmacotherapeutic interventions for clinical illness. The present paper will attempt to elucidate some of the most common physio-pathological phenomena associated with being overweight and obese. We will briefly focus on the manner in which especially excessive visceral adipose tissue contributes to an altered physiological state and pharmacokinetic profile, while highlighting important clinical aspects of comorbid conditions that are frequently observed in this patient cohort.
Gastro-oesophageal reflux disease (GERD), in layman’s terms known as heartburn, is a condition ch... more Gastro-oesophageal reflux disease (GERD), in layman’s terms known as heartburn, is a condition characterised by frequent oesophageal contact with gastric acid. Contrary to what is generally accepted, GERD is not caused by excessive quantities of gastric acid. Rather, symptoms result from any combination of a number of contributing factors, including decreased lower oesophageal sphincter pressure, hiatus hernia (where the stomach protrudes through the diaphragm), reduced oesophageal and gastric clearance and compromised oesophageal mucosa barrier integrity. Although most patients are able to manage GERD symptoms by means of lifestyle changes, chronic and recurrent episodes of reflux may result in erosive oesophagitis, nasal inflammation, dysphagia, i.e. difficulty in swallowing, and even pulmonary complications, e.g. asthma.
Objective Although prescription rates of antidepressants for children and adolescents have increa... more Objective Although prescription rates of antidepressants for children and adolescents have increased, concerns have been raised regarding effects on neurodevelopment and long-term outcome. Using a genetic animal model of depression, this study investigated the long-term effects of pre-pubertal administration of fluoxetine (FLX) on depressive-like behaviour in early adulthood, as well as on central monoaminergic response to an acute stressor. We postulated that pre-pubertal FLX will have lasting effects on animal behaviour and monoaminergic stress responses in early adulthood. Methods Flinders sensitive line (FSL) rats received 10 mg/kg/day FLX subcutaneously from postnatal day 21 (PnD21) to PnD34 (pre-pubertal). Thereafter, following normal housing, rats were either subjected to locomotor testing and the forced swim test (FST) on PnD60 (early adulthood), or underwent surgery for microdialysis, followed on PnD60 by exposure to acute swim stress and measurement of stressor-induced cha...
A large body of evidence suggests that the neuropathology of obsessive-compulsive disorder (OCD) ... more A large body of evidence suggests that the neuropathology of obsessive-compulsive disorder (OCD) lies in the complex neurotransmitter network of the cortico-striatal-thalamo-cortical (CSTC) circuit, where dopamine (DA), serotonin (5HT), glutamate (Glu), and gamma-amino butyric acid (GABA) dysfunction have been implicated in the disorder. Chronic inositol has been found to be effective in specific disorders that respond to selective serotonin reuptake inhibitors (SSRIs), including OCD, panic, and depression. This selective mechanism of action is obscure. Since nigro-striatal DA tracts are subject to 5HT(2) heteroreceptor regulation, one possible mechanism of inositol in OCD may involve its effects on inositol-dependent receptors, especially the 5HT(2) receptor, and a resulting effect on DA pathways in the striatum. In order to investigate this possible interaction, we exposed guinea pigs to oral inositol (1.2 g/kg) for 12 weeks. Subsequently, effects on locomotor behavior (LB) and stereotype behavior (SB), together with possible changes to striatal 5HT(2) and D(2) receptor function, were determined. In addition, the effects of chronic inositol on dexamphetamine (DEX)-induced motor behavior were evaluated. Acute DEX (3 mg/kg, ip) induced a significant increase in both SB and LB, while chronic inositol alone did not modify LA or SB. The behavioral response to DEX was also not modified by chronic inositol pretreatment. However, chronic inositol induced a significant increase in striatal D(2) receptor density (B(max)) with a slight, albeit insignificant, increase in 5HT(2) receptor density. This suggests that D(2) receptor upregulation may play an important role in the behavioral effects of inositol although the role of the 5HT(2) receptor in this response is questionable.
A series of arylalkyl isothiocyanates were evaluated for their ability to inactivate purified cyt... more A series of arylalkyl isothiocyanates were evaluated for their ability to inactivate purified cytochrome P450 2B1 in a reconstituted system. Benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC) occur naturally in several cruciferous vegetables, and the inhibition of cytochrome P450 (P450) enzymes has been implicated in their chemopreventative abilities. The naturally occurring isothiocyanates BITC and PEITC inactivated P450 2B1 in a timeand concentration-dependent manner, whereas the synthetic isothiocyanates phenylpropyl and phenylhexyl isothiocyanate did not result in inactivation, but were potent competitive inhibitors of P450 2B1 activity. The kinetics of inactivation of P450 2B1 by BITC were characterized. The 7-ethoxy-4-(trifluoromethyl)coumarin O-deethylation activity of P450 2B1 was inactivated in a mechanism-based manner. The loss of O-deethylation activity followed pseudo-first-order kinetics, was saturable, and required NADPH. The BITC concentration required for halfmaximal inactivation (K I) was 5.8 µM, and the maximal rate constant for inactivation was 0.66 min-1 at 23°C. BITC was a very efficient inactivator of P450 2B1 with a partition ratio of approximately 9. The mechanism of BITC-mediated inactivation of P450 2B1 was also investigated. More than 80% of the catalytic activity was lost within 12 min with a concomitant loss of approximately 45% in the ability of the reduced enzyme to bind CO. The magnitude of the UV/visible absorption spectrum of the inactivated protein did not decrease significantly, and subsequent HPLC analysis indicated no apparent modification of the heme. HPLC and protein precipitation analyses indicated that the P450 apoprotein was covalently modified by a metabolite of BITC. Determination of the binding stoichiometry indicated that 0.90 (0.16 mol of radiolabeled metabolite was bound per mole of enzyme that was inactivated, suggesting the modification of a single amino acid residue per molecule of enzyme that was inactivated. The results reported here indicate that BITC is a mechanism-based inactivator of P450 2B1 and that inactivation occurs primarily through protein modification.
Animal models are useful in the study of stress disorders in that they offer the possibility of s... more Animal models are useful in the study of stress disorders in that they offer the possibility of stimulating a human condition under controlled conditions in a simpler, more readily understandable system. Stress-related activation of the hypothalamic-pituitaryadrenal (HPA) axis characterized by an increase in plasma corticosterone (CT) levels in the rat is an important manifestation of the physiological stress response. Current available methods for the determination of peripheral corticosterone concentrations from trunk blood, is via a commercially available radio immunoassay (RIA) kit. The aim of this study was to optimize and validate a sensitive, specific and cost-effective high performance liquid chromatography (HPLC) method for the determination of CT levels in plasma of rats. A 500 μl plasma sample was extracted with 5 ml dichloromethane and analyzed by HPLC coupled to a diode array detector at 245 nm. The standard curve was linear over a concentration range of 10 - 500 ng/ml ...
The neuroleptic agent haloperidol (HP) is biotransformed to metabolites such as 4-(4-chlorophenyl... more The neuroleptic agent haloperidol (HP) is biotransformed to metabolites such as 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]-1,2,3,6- tetrahydropyridine (HPTP) and 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]pyridinium (HPP+). In this study, radioligand binding studies were performed using [3H]SCH23390 as a dopamine D1 receptor ligand and [3H]spiperone as a D2 ligand. Ki values for D1 receptors were 35.8 microM and 54.9 microM for HP and HPTP, respectively. Corresponding values for D2 receptors were 39.1 nM and 329.8 nM. These results indicate similar low affinities in the micromolar range for both HP and HPTP at the dopamine D1 receptor, a much higher affinity of both HP and HPTP for the D2 receptor than for the D1 receptor, and that HPTP binds to D2 receptors with a 9-fold lower affinity than HP. The data are consistent with observations in mice that HPTP is a much less potent acute neuroleptic agent than HP.
Rationale, aims and objectives To evaluate asthma management and control in primary care clinics ... more Rationale, aims and objectives To evaluate asthma management and control in primary care clinics so as to design improvements based on guideline-directed outcomes. Methods In this study, all medical records of asthma-diagnosed patients (children as well as adults, entire lifespan, asthma-related visits or not) were retrospectively reviewed as a basis for assessing the level of guideline adherence and asthma control. Six primary health care clinics were visited in the Dr Kenneth Kaunda Municipal District, Potchefstroom, South Africa during May to July 2008, 2009 and 2010. Results A total of 323 asthma patient records were reviewed over the three time slots, resulting in 125, 87, and 111 patients respectively. A suboptimal clinical asthma control picture, with a mere 16% (n = 20) of females and 2% (n = 3) of males with Peak Expiratory Flow (PEF) percentages above 60%, were observed in the initial assessment. Improvement in control was observed during the following time slot, but with an end result in 2010 of no PEF percentages above 60% for males and only 9% (n = 7) for females. Conclusion Over all three of the data collection periods adherence to effectively applied management of asthma guidelines proved to be below the minimum recommended clinical evaluation work-up as set out by the Expert Panel Report 3 (EPR3) of the National Asthma Education and Prevention Program (NAEPP). Applying a greater focus on essential outcomes through different disease management documents resulted in an improved quality of managed care, but still requires dedicated and continuous education and motivation.
An increasing body of research implicates inflammatory processes, including alterations in the ne... more An increasing body of research implicates inflammatory processes, including alterations in the neutrophil-lymphocyte ratio (NLR), in the pathophysiology of psychiatric illness. The deer mouse (Peromyscus maniculatus bairdii) is commonly studied for its naturalistic expression of compulsive-like behaviour. Towards future efforts to gain an understanding of how innate and adaptive immune processes might be involved this model, we set out to study the effects of pegfilgrastim, a pegylated recombinant human granulocyte colony-stimulating factor (g-CSF) analogue, on the NLR of both male and female deer mice. Briefly, 54 deer mice (equally distributed between sexes) were exposed to a single injection with either control or pegfilgrastim (0.1 or 1 mg/kg) (n = 18 per group). Six mice of each group were euthanized on days two, four and seven post-administration, blood collected and the NLR calculated. Our results showed that irrespective of dose, pegfilgrastim resulted in higher NLR values i...
Sinusitis, more aptly referred to as rhinosinusitis, can be described as a symptomatic inflammato... more Sinusitis, more aptly referred to as rhinosinusitis, can be described as a symptomatic inflammatory condition of the paranasal sinuses and the nasal cavity. 1 Generally, the condition is regarded as acute (ARS) if lasting up to 4 weeks, sub-acute when lasting between 4 and 12 weeks, and chronic (CRS) if symptoms present for more than 12 weeks. 2
Osteoporosis is a highly prevalent and debilitating condition that contributes to the risk of fra... more Osteoporosis is a highly prevalent and debilitating condition that contributes to the risk of fracture in both women and men. The current paper will provide a rapid clinical overview of the condition and the current pharmacotherapeutic approaches applied in its treatment. We close with a summary of novel treatment strategies currently being developed and explain the role of sequential combination therapy in the management of established osteoporosis.
Rheumatoid arthritis, an auto-immune disorder, is characterized by chronic inflammation of the jo... more Rheumatoid arthritis, an auto-immune disorder, is characterized by chronic inflammation of the joints, synovial hyperplasia and bone erosion. These pathological features are promoted by a synovial microenvironment featuring B-cell and T-cell infiltrate, synovial fibroblasts and an intricate network of pro-inflammatory cellular messengers – prominent molecular role-players that represent critical targets in the pharmacotherapy of the disease. This review offers a brief overview of the etiopathology of rheumatoid arthritis while focussing on the practical aspects of methotrexate and glucocorticoid use that are of relevance for primary practice.
Pre-exposure prophylaxis (PrEP) refers to the use of antiretroviral drugs to prevent one from acq... more Pre-exposure prophylaxis (PrEP) refers to the use of antiretroviral drugs to prevent one from acquiring human immunodeficiency virus (HIV) infection when engaging in high-risk sexual behaviour. Adequate PrEP initiation is key in the clinical outcome and survival of not only vulnerable and high-risk populations, but also to ensure that a society which is free of HIV, is built.
Type 2 diabetes mellitus (T2DM), previously regarded as being a disease borne exclusively from fo... more Type 2 diabetes mellitus (T2DM), previously regarded as being a disease borne exclusively from following a poor lifestyle, affects at least 415 million individuals worldwide, a number which is believed will increase to 640 million by 2040. As our understanding of T2DM improved over time, it became clear that the condition is underpinned by interactions between poor lifestyle choices and highly varying genetic constructs that involve more than 400 genes. Although a comprehensive review of the genetic architecture of T2DM falls beyond the scope of the current paper, it suffices to say that failure to regard the pathophysiology of T2DM and its subsequent treatment from a drastically different perspective, will result in an increasing burden of the condition on society. This is especially realistic, since despite the fact that oral hypoglycaemic drugs have been used since 1955, current approaches fail to arrest the continuous global rise in the number of T2DM cases.
Please help us populate SUNScholar with the post print version of this article. It can be e-maile... more Please help us populate SUNScholar with the post print version of this article. It can be e-mailed to: scholar@sun.ac.zaGeneeskundePsigiatri
Objective: Depression is suggested to involve disturbances in cholinergic as well as glutamatergi... more Objective: Depression is suggested to involve disturbances in cholinergic as well as glutamatergic pathways, particularly the N-methyl-d-aspartate receptor-mediated release of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP). The aim of this study was to determine whether the Flinders Sensitive Line (FSL) rat, a genetic model of depression, presents with corticolimbic changes in basal acetylcholine (ACh) levels and NO/cGMP signalling. Methods: Basal levels of nitrogen oxides (NOx) and both basal and l-arginine-stimulated nitric oxide synthase (NOS) formation of l-citrulline were analysed in hippocampus and frontal cortex in FSL and control Flinders resistant line (FRL) rats by fluorometric and electrochemical high-performance liquid chromatography, respectively. In addition, ACh and cGMP levels were analysed by liquid chromatography tandem mass spectrometry and radioimmunoassay, respectively. Results: Significantly elevated frontal cortical but reduced hippocampal ACh lev...
Therapeutic drug monitoring (TDM) fulfils an important function in patient health in both the pub... more Therapeutic drug monitoring (TDM) fulfils an important function in patient health in both the public and private healthcare systems. TDM is based on pharmacokinetic principles within the clinical laboratory and several health professionals, from different disciplines, take part in the management and implementation of the whole TDM process. Communication and collaboration between these professionals are extremely important to ensure beneficial TDM and patient care, however, human error plays a major role in the compromising of the TDM process. In this article, we discuss the most common human errors during the TDM process and give guidelines to prevent them. These guidelines must be implemented during all the TDM phases to ensure the patient receives optimal and reliable healthcare.
Overweight and obesity are not only two highly prevalent conditions in the South African society,... more Overweight and obesity are not only two highly prevalent conditions in the South African society, but they also contribute to 6 of the 10 most common causes of death. Further, being overweight not only results in significant metabolic and endocrine disturbances, it also changes how patients respond to most pharmacotherapeutic interventions for clinical illness. The present paper will attempt to elucidate some of the most common physio-pathological phenomena associated with being overweight and obese. We will briefly focus on the manner in which especially excessive visceral adipose tissue contributes to an altered physiological state and pharmacokinetic profile, while highlighting important clinical aspects of comorbid conditions that are frequently observed in this patient cohort.
Gastro-oesophageal reflux disease (GERD), in layman’s terms known as heartburn, is a condition ch... more Gastro-oesophageal reflux disease (GERD), in layman’s terms known as heartburn, is a condition characterised by frequent oesophageal contact with gastric acid. Contrary to what is generally accepted, GERD is not caused by excessive quantities of gastric acid. Rather, symptoms result from any combination of a number of contributing factors, including decreased lower oesophageal sphincter pressure, hiatus hernia (where the stomach protrudes through the diaphragm), reduced oesophageal and gastric clearance and compromised oesophageal mucosa barrier integrity. Although most patients are able to manage GERD symptoms by means of lifestyle changes, chronic and recurrent episodes of reflux may result in erosive oesophagitis, nasal inflammation, dysphagia, i.e. difficulty in swallowing, and even pulmonary complications, e.g. asthma.
Objective Although prescription rates of antidepressants for children and adolescents have increa... more Objective Although prescription rates of antidepressants for children and adolescents have increased, concerns have been raised regarding effects on neurodevelopment and long-term outcome. Using a genetic animal model of depression, this study investigated the long-term effects of pre-pubertal administration of fluoxetine (FLX) on depressive-like behaviour in early adulthood, as well as on central monoaminergic response to an acute stressor. We postulated that pre-pubertal FLX will have lasting effects on animal behaviour and monoaminergic stress responses in early adulthood. Methods Flinders sensitive line (FSL) rats received 10 mg/kg/day FLX subcutaneously from postnatal day 21 (PnD21) to PnD34 (pre-pubertal). Thereafter, following normal housing, rats were either subjected to locomotor testing and the forced swim test (FST) on PnD60 (early adulthood), or underwent surgery for microdialysis, followed on PnD60 by exposure to acute swim stress and measurement of stressor-induced cha...
A large body of evidence suggests that the neuropathology of obsessive-compulsive disorder (OCD) ... more A large body of evidence suggests that the neuropathology of obsessive-compulsive disorder (OCD) lies in the complex neurotransmitter network of the cortico-striatal-thalamo-cortical (CSTC) circuit, where dopamine (DA), serotonin (5HT), glutamate (Glu), and gamma-amino butyric acid (GABA) dysfunction have been implicated in the disorder. Chronic inositol has been found to be effective in specific disorders that respond to selective serotonin reuptake inhibitors (SSRIs), including OCD, panic, and depression. This selective mechanism of action is obscure. Since nigro-striatal DA tracts are subject to 5HT(2) heteroreceptor regulation, one possible mechanism of inositol in OCD may involve its effects on inositol-dependent receptors, especially the 5HT(2) receptor, and a resulting effect on DA pathways in the striatum. In order to investigate this possible interaction, we exposed guinea pigs to oral inositol (1.2 g/kg) for 12 weeks. Subsequently, effects on locomotor behavior (LB) and stereotype behavior (SB), together with possible changes to striatal 5HT(2) and D(2) receptor function, were determined. In addition, the effects of chronic inositol on dexamphetamine (DEX)-induced motor behavior were evaluated. Acute DEX (3 mg/kg, ip) induced a significant increase in both SB and LB, while chronic inositol alone did not modify LA or SB. The behavioral response to DEX was also not modified by chronic inositol pretreatment. However, chronic inositol induced a significant increase in striatal D(2) receptor density (B(max)) with a slight, albeit insignificant, increase in 5HT(2) receptor density. This suggests that D(2) receptor upregulation may play an important role in the behavioral effects of inositol although the role of the 5HT(2) receptor in this response is questionable.
A series of arylalkyl isothiocyanates were evaluated for their ability to inactivate purified cyt... more A series of arylalkyl isothiocyanates were evaluated for their ability to inactivate purified cytochrome P450 2B1 in a reconstituted system. Benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC) occur naturally in several cruciferous vegetables, and the inhibition of cytochrome P450 (P450) enzymes has been implicated in their chemopreventative abilities. The naturally occurring isothiocyanates BITC and PEITC inactivated P450 2B1 in a timeand concentration-dependent manner, whereas the synthetic isothiocyanates phenylpropyl and phenylhexyl isothiocyanate did not result in inactivation, but were potent competitive inhibitors of P450 2B1 activity. The kinetics of inactivation of P450 2B1 by BITC were characterized. The 7-ethoxy-4-(trifluoromethyl)coumarin O-deethylation activity of P450 2B1 was inactivated in a mechanism-based manner. The loss of O-deethylation activity followed pseudo-first-order kinetics, was saturable, and required NADPH. The BITC concentration required for halfmaximal inactivation (K I) was 5.8 µM, and the maximal rate constant for inactivation was 0.66 min-1 at 23°C. BITC was a very efficient inactivator of P450 2B1 with a partition ratio of approximately 9. The mechanism of BITC-mediated inactivation of P450 2B1 was also investigated. More than 80% of the catalytic activity was lost within 12 min with a concomitant loss of approximately 45% in the ability of the reduced enzyme to bind CO. The magnitude of the UV/visible absorption spectrum of the inactivated protein did not decrease significantly, and subsequent HPLC analysis indicated no apparent modification of the heme. HPLC and protein precipitation analyses indicated that the P450 apoprotein was covalently modified by a metabolite of BITC. Determination of the binding stoichiometry indicated that 0.90 (0.16 mol of radiolabeled metabolite was bound per mole of enzyme that was inactivated, suggesting the modification of a single amino acid residue per molecule of enzyme that was inactivated. The results reported here indicate that BITC is a mechanism-based inactivator of P450 2B1 and that inactivation occurs primarily through protein modification.
Animal models are useful in the study of stress disorders in that they offer the possibility of s... more Animal models are useful in the study of stress disorders in that they offer the possibility of stimulating a human condition under controlled conditions in a simpler, more readily understandable system. Stress-related activation of the hypothalamic-pituitaryadrenal (HPA) axis characterized by an increase in plasma corticosterone (CT) levels in the rat is an important manifestation of the physiological stress response. Current available methods for the determination of peripheral corticosterone concentrations from trunk blood, is via a commercially available radio immunoassay (RIA) kit. The aim of this study was to optimize and validate a sensitive, specific and cost-effective high performance liquid chromatography (HPLC) method for the determination of CT levels in plasma of rats. A 500 μl plasma sample was extracted with 5 ml dichloromethane and analyzed by HPLC coupled to a diode array detector at 245 nm. The standard curve was linear over a concentration range of 10 - 500 ng/ml ...
The neuroleptic agent haloperidol (HP) is biotransformed to metabolites such as 4-(4-chlorophenyl... more The neuroleptic agent haloperidol (HP) is biotransformed to metabolites such as 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]-1,2,3,6- tetrahydropyridine (HPTP) and 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]pyridinium (HPP+). In this study, radioligand binding studies were performed using [3H]SCH23390 as a dopamine D1 receptor ligand and [3H]spiperone as a D2 ligand. Ki values for D1 receptors were 35.8 microM and 54.9 microM for HP and HPTP, respectively. Corresponding values for D2 receptors were 39.1 nM and 329.8 nM. These results indicate similar low affinities in the micromolar range for both HP and HPTP at the dopamine D1 receptor, a much higher affinity of both HP and HPTP for the D2 receptor than for the D1 receptor, and that HPTP binds to D2 receptors with a 9-fold lower affinity than HP. The data are consistent with observations in mice that HPTP is a much less potent acute neuroleptic agent than HP.
Rationale, aims and objectives To evaluate asthma management and control in primary care clinics ... more Rationale, aims and objectives To evaluate asthma management and control in primary care clinics so as to design improvements based on guideline-directed outcomes. Methods In this study, all medical records of asthma-diagnosed patients (children as well as adults, entire lifespan, asthma-related visits or not) were retrospectively reviewed as a basis for assessing the level of guideline adherence and asthma control. Six primary health care clinics were visited in the Dr Kenneth Kaunda Municipal District, Potchefstroom, South Africa during May to July 2008, 2009 and 2010. Results A total of 323 asthma patient records were reviewed over the three time slots, resulting in 125, 87, and 111 patients respectively. A suboptimal clinical asthma control picture, with a mere 16% (n = 20) of females and 2% (n = 3) of males with Peak Expiratory Flow (PEF) percentages above 60%, were observed in the initial assessment. Improvement in control was observed during the following time slot, but with an end result in 2010 of no PEF percentages above 60% for males and only 9% (n = 7) for females. Conclusion Over all three of the data collection periods adherence to effectively applied management of asthma guidelines proved to be below the minimum recommended clinical evaluation work-up as set out by the Expert Panel Report 3 (EPR3) of the National Asthma Education and Prevention Program (NAEPP). Applying a greater focus on essential outcomes through different disease management documents resulted in an improved quality of managed care, but still requires dedicated and continuous education and motivation.
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