Screening of Living Kidney Donors for Genetic Diseases Using a Comprehensive Genetic Testing Strategy.

Related living kidney donors (LKDs) are at higher risk of end-stage renal disease (ESRD) compared with unrelated LKDs. A genetic panel was developed to screen 115 genes associated with renal diseases. We used this panel to screen six negative controls, four transplant candidates with presumed genetic renal disease and six related LKDs. After removing common variants, pathogenicity was predicted using six algorithms to score genetic variants based on conservation and function. All variants were evaluated in the context of patient phenotype and clinical data. We identified causal variants in three of the four transplant candidates. Two patients with a family history of autosomal dominant polycystic kidney disease segregated variants in PKD1. These findings excluded genetic risk in three of four relatives accepted as potential LKDs. A third patient with an atypical history for Alport syndrome had a splice site mutation in COL4A5. This pathogenic variant was excluded in a sibling accepted as an LKD. In another patient with a strong family history of ESRD, a negative genetic screen combined with negative comparative genomic hybridization in the recipient facilitated counseling of the related donor. This genetic renal disease panel will allow rapid, efficient and cost-effective evaluation of related LKDs.

Risk of water contamination by nitrogen in Canada as estimated by the IROWC-N model.

With increasing amounts of nitrogen (N) being added to farmland in the form of fertilizer and manure to optimize crop yields, and more broadly, to meet the growing demands for food, feed and energy, there are public concerns regarding its possible negative impact on the environment. An optimal balance between N requirements for production versus efficient N use is required, so as to minimize N losses from the agricultural system. An agri-environmental indicator i.e., the Indicator of the Risk of Water Contamination by Nitrogen (IROWC-N) was developed to assess the risk of N moving from agricultural areas into groundwater and/or nearby surface water bodies. The indicator linked the quantity of mineral nitrogen remaining in the soil at harvest, i.e., the Residual Soil Nitrogen (RSN) indicator, and the subsequent climatic conditions during the winter period. The results were assessed in terms of nitrate lost through leaching and nitrate concentration in the drainage water, expressed in five IROWC-N risk classes. Unlike previous versions of the indicator, the current model provided a more complete description of the soil-water balance, including the calculation of rainfall interception by crops, surface runoff, actual evapotranspiration and soil-water contents. Consequently, the current IROWC-N estimates differed markedly from those obtained previously. Between 1981 and 2006, the risk of water contamination by N in Canada was small, and reflected what was happening in the three Prairie provinces where 85% of Canada's farmland is located. However, the aggregated IROWC-N index, which is a combination of all five risk classes, increased steadily by 2.3% per year, from 6.7 in 1981 to 10.6 in 2006. The proportion of farmland in the very low IROWC-N risk class decreased from 88 to 78%; correspondingly, the proportion in the low risk class increased from 2 to 12%. The proportion of farmland in the moderate-, high- and very high-risk classes changed by less than 3% over time. The trends in IROWC-N in the Atlantic provinces were significantly worse than the national trend; for example, in Atlantic Canada, the aggregated IROWC-N index tripled from 27.8 in 1981 to 87.5 in 2006. Increases in fertilizer use (except in British Columbia), increases in livestock numbers in Manitoba and the Atlantic provinces, and an increase in legume crop acreage were the main factors that contributed to the increase in IROWC-N estimates. Climatic factors were also involved, as droughts reduced yields, N uptake and N leaching in many regions of Canada in 2001.

Seroprevalence of dengue in Trinidad using rapid test kits: a cord blood survey.

A cross-sectional sero-epidemiological study was conducted to determine the prevalence of dengue in Trinidad. Two commercial rapid test kits, PanBio Dengue Duo IgM and IgG Rapid Strip Test and the Bio-Check Plus Dengue G/M Cassette Test (Brittney) were used. The immunosorbent assay (ELISA) (FOCUS Technologies, California) was used as the control. One hundred and twenty five cord blood samples were collected (46 from Mt. Hope Women's Hospital (MH) and 79 from the San Fernando General Hospital (SF)). All blood samples were tested in accordance with the two rapid kits and ELISA assay manufacturer's instructions. From 125 cord blood samples, the IgG FOCUS ELISA results showed 93.5 and 95% infections at MH and SF, respectively. Whereas the Brittney and PanBio kits showed 10.9 and 5.1%, and 26.1 and 50.6% for MH and SF, respectively. Based on the FOCUS ELISA (control) assays, the combined seroprevalence rate from north and south Trinidad was 94.4%. IgG and IgM sensitivity and specificity levels were higher in the PanBio than Brittney test kits. The high seroprevalence rates observed in Trinidad are discussed to stimulate more research to explain this phenomenon and to prevent the Southeast Asian scenario from developing in the Americas.

Acodazole hydrochloride: phase I trial, pharmacokinetics, and evaluation of cardiotoxicity in dogs.

Acodazole (NSC 305884) was examined in a Phase I trial evaluating a 1-h infusion repeated every 21 days in 37 patients with advanced carcinomas. Cardiac toxicity was dose-limiting at 1370 mg/m2, manifested as multiple premature ventricular contractions, QTc interval prolongation, and decreasing heart rate. Other toxicities included mild to moderate nausea and vomiting and local reaction near the i.v. injection site requiring the use of central venous catheters. Antineoplastic activity was not observed. Acodazole levels assayed by high-performance liquid chromatography disclosed a peak plasma level of 19 +/- 4 (SEM) micrograms/ml for 1370 mg/m2. Acodazole plasma levels decreased in a triphasic manner over a 100-fold range. The volume of distribution at steady state was 238 +/- 18 liter/m2 suggesting extensive tissue binding. The total body clearance was 13.6 +/- 0.9 liter/h/m2; the percentage of urinary excretion was 29 +/- 2% for 48 h. To evaluate cardiac toxicity, acodazole was administered to five dogs at 2262 mg/m2 (1-h infusion) which provided plasma concentrations similar to those achieved at 1370 mg/m2 in humans. Consistent findings in dogs were drug-related prolongation of QTc intervals, and reduction in heart rate, left ventricular dP/dt, and mean blood pressures. Clinical development of acodazole requires studies to further elucidate and alleviate this cardiac toxicity.

Critical Risk Results - An Update on International Initiatives.

Direct communication of significant (often life-threatening) results is a universally acknowledged role of the pathology laboratory, and an important contributor to patient safety. Amongst the findings of a recent survey of 871 laboratories from 30 countries by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM), only 3 tests were noted to be common to 90% of alert lists, and only 48% of laboratories consulted clinicians in developing these alert lists despite ISO15189 recommendations to do so. These findings are similar to previous national surveys demonstrating significant variation worldwide in how critical risk results are managed and also in how these protocols are developed. In order to promote "best practice" and harmonization of critical risk results management, guidelines and recommendations have been published, most recently by Clinical and Laboratory Standards Institute (CLSI) and Australasian Association of Clinical Biochemists (AACB). These statements in particular have placed strong emphasis on patient risk and risk assessment in the management of critical risk results. This focus has resulted in recommendations to adopt new terminology, the consideration of risk assessment when compiling alert tables, consultative involvement of laboratory users in setting up protocols, and the need for outcome-based evidence to support our practices. With time it is expected that emerging evidence and technological improvements will facilitate the advancement of laboratories down this path to harmonization, best practice, and improve patient safety.

Diastolic filling in acute left ventricular dysfunction: role of the pericardium.

Patients with congestive heart failure and elevated left ventricular filling pressures demonstrate an abnormal pattern of diastolic filling that is characterized by a redistribution of diastolic filling to early diastole with reduced reliance on late diastolic filling. The diastolic filling pattern superficially resembles that which is seen with constrictive pericarditis. To examine potential mechanisms for these clinical findings, a model of ischemic left ventricular dysfunction was produced in seven dogs by repeated coronary microsphere embolization, producing a dilated left ventricle with reduced systolic function. Measurements of left ventricular systolic and end-diastolic pressures, rate of rise of left ventricular pressure (dP/dt) and echocardiographic end-diastolic and end-systolic areas were obtained at baseline, during intermediate embolization (moderate left ventricular systolic dysfunction, dilation and mild increases in left ventricular end-diastolic pressure), postembolization (further embolization resulting in severe left ventricular systolic dysfunction, dilation and marked increases in left ventricular end-diastolic pressure), after thoracotomy and after pericardiectomy. The filling fraction at 1/3 and 1/2 of diastole and the time constant of left ventricular pressure decline were also determined. Repetitive coronary microembolization caused progressive left ventricular dilation and decreasing systolic function, which did not change after opening the chest or pericardium. The filling fraction at 1/3 and 1/2 of diastole declined with intermediate embolization (12.0 +/- 5.6% and 23.1 +/- 10.8%, respectively) as compared with baseline values (29.0 +/- 11.9%, 42.9 +/- 15.6%, p less than 0.05). After embolization, there was an increase in the 1/3 and the 1/2 filling fraction (47.5 +/- 8.9%, 72.0 +/- 6.0%, respectively, p less than 0.01) as compared with baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of nitroglycerin-induced reduction of left ventricular filling pressure on diastolic filling in acute dilated heart failure.

Recent information has suggested that early diastolic filling may be influenced by the left ventricular filling pressure, especially in the failing left ventricle. Acute severe left ventricular dysfunction was induced in 14 dogs by severe left ventricular global ischemia produced by left main coronary artery microsphere embolization until the left ventricular end-diastolic pressure was greater than or equal to 20 mm Hg. To assess the importance of left ventricular filling pressure on left ventricular diastolic filling, nitroglycerin was infused and titrated to reduce left ventricular end-diastolic pressure to less than 15 mm Hg in seven dogs, whereas the remaining seven dogs were observed for 1 h after acute severe left ventricular dysfunction. In both groups of dogs, severe left ventricular dysfunction resulted in left ventricular dilation and elevation of end-diastolic pressure, reduction in area ejection fraction (echocardiographically determined) and an early redistribution of diastolic filling (increased filling fractions at one-third and one-half diastole) despite prolongation of the time constant of left ventricular pressure decline. Pressure-area plots shifted upward and rightward with severe left ventricular dysfunction and were unchanged at 1 h as were all other variables. Nitroglycerin infusion reduced left ventricular size and filling pressure, redistributed diastolic filling to later in diastole as characterized by reduced filling fraction at one-third diastole (left ventricular dysfunction 48.8 +/- 9.7%, nitroglycerin 17.9 +/- 7.9%, p less than 0.001) and shifted downward left ventricular pressure-area plots. Nitroglycerin also improved the time constant of relaxation (left ventricular dysfunction 83 +/- 15 ms, nitroglycerin 52 +/- 15 ms, p less than 0.001) and lengthened the diastolic filling period.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of inotropic and vasodilator therapy on left ventricular diastolic filling in dogs with severe left ventricular dysfunction.

Inotropic and vasodilator therapy for congestive heart failure improve left ventricular systolic performance by different mechanisms. However, the nature and extent to which diastolic filling is altered have not been well described. Acute severe left ventricular dysfunction was induced in 21 dogs by severe left ventricular global ischemia produced by left main coronary artery microsphere embolization until left ventricular end-diastolic pressure was greater than or equal to 18 mm Hg. Dobutamine was infused in seven dogs until the peak positive first derivative of left ventricular pressure (dP/dt) increased by greater than or equal to 33%. Nitroprusside was infused in seven dogs until left ventricular end-diastolic pressure was less than 15 mm Hg. Seven dogs were observed for 1 h after the induction of acute severe left ventricular dysfunction and served as the control group. In all groups of dogs, severe left ventricular dysfunction resulted in left ventricular dilation, reduction in area ejection fraction, elevation of left ventricular end-diastolic pressure and an early redistribution of diastolic filling (increased 1/3 and 1/2 filling fractions) despite a markedly abnormal time constant of relaxation. No changes were noted in any variable after 1 h of observation in the seven control dogs. Nitroprusside reduced left ventricular size and filling pressure, increased cardiac output, improved relaxation and redistributed diastolic filling to later in diastole as characterized by a reduced 1/3 filling fraction (19.4 +/- 7.4% versus 51.4 +/- 10%, p less than 0.001). The pressure-area curve was shifted downward and leftward.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of verapamil on infarct size in dogs subjected to coronary artery occlusion with transient reperfusion.

Reocclusion after successful coronary reperfusion occurs in 15 to 35% of patients receiving thrombolytic therapy for acute myocardial infarction. The present study was designed to simulate the clinical situation of reocclusion and determine whether verapamil might be effective in reducing myocardial necrosis and preserving high energy phosphates in this setting. Pentobarbital-anesthetized, open chest dogs underwent occlusion of the left anterior descending coronary artery for 2 hours followed by 1 hour of reperfusion and a further 4 hours of coronary artery occlusion. Treatment with verapamil (intravenous bolus dose of 0.2 mg/kg body weight followed by infusion of 0.56 +/- 0.14 mg/kg per h) was begun 1 hour after occlusion and infusion was continued for the remainder of the experiment. The dose of verapamil was adjusted to lower mean arterial pressure to approximately 90 mm Hg. The area at risk was determined by intraatrial injection of monastral blue dye and the area of necrosis was assessed by triphenyltetrazolium chloride staining. In vivo myocardial needle biopsy for determination of adenosine triphosphate and creatine phosphate was performed at the end of the experiment. The area of the left ventricle at risk was similar in both groups (control [n = 8], 20.2 +/- 1.6% versus verapamil-treated [n = 9], 23.1 +/- 2.9%; p = NS). The area of necrosis expressed as a percent of the area at risk was reduced in the verapamil-treated group compared with the control group (43.3 +/- 5.0% versus 63.1 +/- 6.8%, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The autoperfusion balloon angioplasty catheter limits myocardial ischemia and necrosis during prolonged balloon inflation.

A new balloon angioplasty catheter with multiple proximal and distal side holes has previously been shown to allow significant protection from ischemia during a 3 min balloon inflation in a coronary artery. Because of the potential benefits of very long periods of inflation, 21 anesthetized thoracotomized dogs were randomized to left circumflex coronary artery occlusion with either a standard or an autoperfusion balloon catheter for 90 min. Nine dogs sustained ventricular fibrillation before completing the study, eight after standard balloon inflation and one after autoperfusion balloon inflation (p = 0.04). ST segment elevation was 0.45 +/- 0.13 mV after 15 min of standard balloon inflation versus -0.03 +/- 0.03 mV after autoperfusion balloon inflation (p less than 0.001). Regional myocardial blood flow was 0.02 +/- 0.01 ml/min per g after 30 min of standard balloon inflation compared with 0.78 +/- 0.23 ml/min per g in the group subjected to autoperfusion balloon inflation (p = 0.01). The area of necrosis/area at risk in the standard catheter group was 40.4 +/- 19.3% versus 1.2 +/- 1.2% for the autoperfusion catheter group (p = 0.01). Thus, the autoperfusion catheter preserves blood flow and limits myocardial ischemia and necrosis despite 90 min of balloon inflation.

Linkage of otosclerosis to a third locus (OTSC3) on human chromosome 6p21.3-22.3.

Clinical otosclerosis (OMIM 166800/605727) has a prevalence of 0.2-1% among white adults, making it the single most common cause of hearing impairment in this group. It is caused by abnormal bone homeostasis of the otic capsule with the consequent development of sclerotic foci that invade the stapedio-vestibular joint (oval window) interfering with free motion of the stapes. Impaired ossicular chain mobility results in a conductive hearing loss. We identified the first locus for otosclerosis (OTSC1) on chromosome 15 in 1998 and reported a second locus (OTSC2) on chromosome 7 last year. Here we present results of a genome wide linkage study on a large Cypriot family segregating otosclerosis. Results of this study exclude linkage to OTSC1 and OTSC2 and identify a third locus, OTSC3, on chromosome 6p. The defined OTSC3 interval covers the HLA region, consistent with reported associations between HLA-A/HLA-B antigens and otosclerosis.

Designing environmental research for impact.

Transdisciplinary research, involving close collaboration between researchers and the users of research, has been a feature of environmental problem solving for several decades, often spurred by the need to find negotiated outcomes to intractable problems. In 2005, the Australian government allocated funding to its environment portfolio for public good research, which resulted in consecutive four-year programmes (Commonwealth Environmental Research Facilities, National Environmental Research Program). In April 2014, representatives of the funders, researchers and research users associated with these programmes met to reflect on eight years of experience with these collaborative research models. This structured reflection concluded that successful multi-institutional transdisciplinary research is necessarily a joint enterprise between funding agencies, researchers and the end users of research. The design and governance of research programmes need to explicitly recognise shared accountabilities among the participants, while respecting the different perspectives of each group. Experience shows that traditional incentive systems for academic researchers, current trends in public sector management, and loose organisation of many end users, work against sustained transdisciplinary research on intractable problems, which require continuity and adaptive learning by all three parties. The likelihood of research influencing and improving environmental policy and management is maximised when researchers, funders and research users have shared goals; there is sufficient continuity of personnel to build trust and sustain dialogue throughout the research process from issue scoping to application of findings; and there is sufficient flexibility in the funding, structure and operation of transdisciplinary research initiatives to enable the enterprise to assimilate and respond to new knowledge and situations.

Vanadium and other trace elements in patients taking lithium.

The serum concentrations of 24 trace elements were measured by neutron activation analysis in 32 patients on long-term lithium treatment and 32 age- and sex-matched healthy controls. Whole blood and hair samples were also taken from a number of these subjects. Compared to controls, patients on lithium were found to have a lower serum vanadium, a lower serum cobalt, and an elevated serum aluminium level. These findings are discussed.

The effects of SB 206284A, a novel neuronal calcium-channel antagonist, in models of cerebral ischemia.

The effects of SB 206284A, 1-[7-(4-benzyloxyphenoxy)heptyl] piperidine hydrochloride, have been investigated in vitro on calcium and sodium currents in rat-cultured dorsal root ganglion (DRG) neurones and potassium-mediated calcium influx in rat synaptosomes. Cardiovascular hemodynamic effects in both anesthetized and conscious rats, and neuroprotective activity in in vivo cerebral ischemia models were also investigated. In the rat DRG cells, SB 206284A caused almost complete block of the sustained inward Ca2+ current (IC50 = 2.4 microM), suggesting that the compound is an effective blocker of slowly inactivating, high-voltage calcium current. SB 206284A reduced locomotor hyperactivity in the gerbil bilateral carotid artery occlusion model without affecting ischemia-induced damage in the hippocampal CA1 region. In the rat middle cerebral artery occlusion model, SB 206284A reduced lesion volume in the posterior forebrain, and in the rat photochemical cortical lesion model, lesion volume was reduced even when treatment was delayed until 4 hours after occlusion. At neuroprotective doses, SB 206284A had no cardiovascular effects. These findings show that SB 206284A is a novel calcium channel antagonist that shows neuroprotective properties.

TR3 death receptor expression in the normal and ischaemic brain.

Members of the death receptor family may play a prominent role in developmental and pathological neuronal cell death. We report the expression of the TR3 and TR7 death receptors in the adult human and rat central nervous system. Whereas expression of TR3 appears to be high in the human cerebellum, with lower levels in other brain regions, robust expression is observed in many regions of the rat brain. We also analyzed modulation of death receptor expression in an in vivo rat model of acute stroke. In contrast to tumor necrosis factor receptor 1, Fas and p75(NGFR), which all show up-regulation specifically in lesioned cortex of the permanent middle cerebral artery occlusion model of stroke. TR3 shows a rapid global increase in both lesioned and unlesioned brain. In comparison, the recently described death receptor TR7 shows no change in this model. These data indicate that the death receptors show clear differences in patterns of expression in response to ischemic injury. ¿ 2000 IBRO. Published by Elsevier Science Ltd.

Effect of reperfusion and hyperemia on the myocardial distribution of technetium-99m t-butylisonitrile.

Technetium-99m t-butylisonitrile ([99mTc]TBI) is a promising new radiotracer for myocardial imaging. Its myocardial uptake is sufficiently high in humans to permit planar, tomographic, and gated images of excellent technical quality. We studied the behavior of [99mTc]TBI in the dog at rest and under conditions of hyperemia and reperfusion in order to determine the relationship between [99mTc]TBI myocardial concentration and blood flow. After permanent occlusion of the left anterior descending artery, the correlation between the relative myocardial concentration of [99mTc]TBI and regional myocardial blood flow (RMBF) measured with radiolabeled microspheres was excellent. In a dog model of transient hyperemia, the concentration of [99mTc]TBI was directly related to blood flow but underestimated the degree of hyperemia. Technetium-99m TBI redistributed into transiently ischemic myocardium. The myocardial concentrations of [99mTc]TBI and thallium-201(201TI) in transiently ischemic myocardium were similar at 10 and 30 min following reperfusion and were significantly higher than blood flow prior to reperfusion. When [99mTc]TBI was injected into the left anterior descending artery, the washout was slow, falling to 78% of initial activity at 120 min after injection. In conclusion, [99mTc]TBI reflects regional myocardial blood flow accurately in ischemic and normal resting myocardium and underestimates blood flow at high flows. The rate of myocardial redistribution after reperfusion is similar for [99mTc]TBI and 201TI.

Amelioration of ischemia during angioplasty of the left anterior descending coronary artery with an autoperfusion catheter.

A new autoperfusion balloon angioplasty catheter with sideholes proximal and distal to the balloon--facilitating distal blood flow during inflation--was compared with standard angioplasty catheters in a prospective, randomized study with blinded data analysis. Hemodynamic and electrocardiographic markers of ischemia after 1 minute of standard or autoperfusion catheter inflations were compared with ischemia after control inflation with standard balloons. In the patient group randomized to standard balloon inflation only, ST-segment elevation after control inflation with a standard balloon catheter was 0.37 +/- 0.04 mV; ST-segment elevation after final balloon inflation with a standard catheter was unchanged at 0.35 +/- 0.04 mV (difference not significant). In the group randomized to the autoperfusion catheter, control inflation with a standard catheter resulted in 0.48 +/- 0.1 mV ST elevation; final inflation with the autoperfusion catheter demonstrated 0.16 +/- 0.09 mV ST elevation (p less than 0.005). Autoperfusion catheter inflation was continued for 2 minutes without change in electrocardiographic findings: ST segments remained at 0.08 +/- 0.03 mV, unchanged from 0.07 +/- 0.03 mV before angioplasty (difference not significant). Thus, while coronary angioplasty performed with standard catheters resulted in marked ST-segment elevation, in patients undergoing angioplasty with the autoperfusion catheter, ischemia was generally not seen, despite sustained balloon inflation for 2 minutes.

The effect of beta-adrenoceptor blocking agents, with differing ancillary properties, on the arrhythmias resulting from acute coronary artery ligation in anaesthetized rats.

The effects of several beta-adrenoceptor blocking agents, [+), (-) and (+/-)-oxprenolol, p-oxprenolol, practolol, propranolol and timolol) were investigated on the ventricular arrhythmias occurring within the first 30 min of acutely ligating the main left coronary artery in anaesthetized rats. The degree of cardiac and vascular beta-adrenoceptor blockade was also assessed. All the compounds exhibited antiarrhythmic activity under these conditions. The degree of cardiac beta-adrenoceptor blockade required for this protection was less for the cardioselective agents, p-oxprenolol and practolol, than for the non-selective beta-adrenoceptor blocking agents. A comparison of the two isomers of oxprenolol demonstrated that the (-)-isomer markedly suppressed ischaemic arrhythmias (ventricular ectopic beats, incidence and duration of ventricular tachycardia and duration of ventricular fibrillation) more effectively than the (+)-isomer. Compounds possessing intrinsic sympathomimetic activity (ISA) caused less marked haemodynamic changes (in equivalent beta-blocking doses) than those that did not possess this ancillary property. The membrane stabilizing activity of oxprenolol and p-oxprenolol did not appear to contribute to the antiarrhythmic activity of these agents; however, the membrane stabilizing activity of propranolol may contribute to its effectiveness. In all the drugs studied, the main pharmacological property required to suppress early postischaemic arrhythmias is blockade of cardiac beta-adrenoceptors.

Pentoxifylline does not reduce infarct size in a canine model of acute myocardial infarction.

1. The effect of the haemorrheological agent pentoxifylline was investigated in a canine model of acute myocardial infarction, induced by occlusion of the left anterior descending coronary for 6 h. Thirty minutes post-occlusion the dogs were randomized to receive either distilled water or pentoxifylline (0.3 mg kg-1 min-1 for 1 h followed by 0.15 mg kg-1 min-1 for 4.5 h) intravenously. 2. At 6 h post-occlusion the in vivo area at risk was determined with monastral blue dye and the area of necrosis was determined with triphenyltetrazolium chloride. The area at risk was 16.5 +/- 1.3% in the control group (n = 10) and 17.2 +/- 1.8% in the pentoxifylline treated group (n = 10; NS). The area of necrosis was 12.3 +/- 1.9% in the control group and 11.9 +/- 2.2% in the pentoxifylline treated group (NS). The area of necrosis expressed as a percentage of the area at risk was 69.3 +/- 7.7% in the control group and 63.6 +/- 7.4% in the pentoxifylline treated group (NS). 3. Pentoxifylline had no significant effects on heart rate, systolic or diastolic blood pressure. Regional myocardial blood flow, measured by the radioactive microsphere technique, was not significantly different between the groups. 4. Thus, pentoxifylline does not reduce infarct size in this model of acute myocardial infarction and does not enhance coronary collateral blood flow.

Profile of SB-204269, a mechanistically novel anticonvulsant drug, in rat models of focal and generalized epileptic seizures.

1. Earlier optimization of structure-activity relationships in a novel series of 4-(benzoylamino)-benzopyrans, led to the discovery of SB-204269 (trans-(+)-6-acetyl-4S-(4-fluorobenzoylamino)-3,4-dihydro-2, 2-dimethyl-2H-benzo[b]pyran-3R-ol, hemihydrate), a potent orally-active anticonvulsant in the mouse maximal electroshock seizure threshold (MEST) test. 2. Studies have now been undertaken to determine the effects of SB-204269 in a range of seizure models and tests of neurological deficits in rats. In addition, the compound has been evaluated in a series of in vitro mechanistic assays. 3. SB-204269 proved to be an orally-effective anticonvulsant agent, at doses (0.1-30 mg Kg-1) devoid of overt behavioural depressant properties, in models of both electrically (MEST and maximal electroshock (MEST)) and chemically (i.v. pentylenetetrazol (PTZ) infusion)-evoked tonic extension seizures. However, the compound did not inhibit PTZ-induced myoclonic seizures at doses up to 30 mg kg-1, p.o. 4. SB-204269 also selectively reduced focal electrographic seizure activity in an in vitro elevated K+ rat hippocampal slice model at concentrations (0.1-10 microM) that had no effect on normal synaptic activity and neuronal excitability. 5. In all of these seizure models, SB-204269 was equivalent or better than the clinically established antiepileptic drugs carbamazepine and lamotrigine, in terms of anticonvulsant potency and efficacy. 6. Unlike SB-204269, the corresponding trans 3S,4R enantiomer, SB-204268, did not produce marked anticonvulsant effects, an observation in accord with previous findings for other related pairs of trans enantiomers in the benzopyran series. 7. In the rat accelerating rotarod test, a sensitive paradigm for the detection of neurological deficits such as sedation and motor incoordination, SB-204269 was inactive even at doses as high as 200 mg kg-1, p.o. This was reflected in the excellent therapeutic index (minimum significantly effective dose in the rotarod test/ED50 in the MES test) for SB-204269 of > 31, as compared to equivalent values of only 7 and 13 for carbamazepine and lamotrigine, respectively. 8. At concentrations (> or = 10 microM) well above those required to produce anticonvulsant activity in vivo (i.e. 0.1 microM in brain), SB-204269 did not interact with many of the well known mechanistic targets for established antiepileptic drugs (e.g. Na+ channels or GABAergic neurotransmission). Subsequent studies have shown that the anticonvulsant properties of SB-204269 are likely to be mediated by a novel stereospecific binding site present in the CNS. 9. The overall efficacy profile in rodent seizure models, together with a minimal liability for inducing neurological impairment and an apparently unique mechanism of action, highlight the therapeutic potential of SB-204269 for the treatment of refractory partial and generalized tonic-clonic seizures.