Modeling Superimposed Preeclampsia Using Ang II (Angiotensin II) Infusion in Pregnant Stroke-Prone Spontaneously Hypertensive Rats.

Hypertensive disorders of pregnancy are the second leading cause of maternal deaths worldwide. Superimposed preeclampsia is an increasingly common problem and often associated with impaired placental perfusion. Understanding the underlying mechanisms and developing treatment options are crucial. The pregnant stroke-prone spontaneously hypertensive rat has impaired uteroplacental blood flow and abnormal uterine artery remodeling. We used Ang II (angiotensin II) infusion in pregnant stroke-prone spontaneously hypertensive rats to mimic the increased cardiovascular stress associated with superimposed preeclampsia and examine the impact on the maternal cardiovascular system and fetal development. Continuous infusion of Ang II at 500 or 1000 ng/kg per minute was administered from gestational day 10.5 until term. Radiotelemetry and echocardiography were used to monitor hemodynamic and cardiovascular changes, and urine was collected prepregnancy and throughout gestation. Uterine artery myography assessed uteroplacental vascular function and structure. Fetal measurements were made at gestational day 18.5, and placentas were collected for histological and gene expression analyses. The 1000 ng/kg per minute Ang II treatment significantly increased blood pressure (P<0.01), reduced cardiac output (P<0.05), and reduced diameter and increased stiffness of the uterine arteries (P<0.01) during pregnancy. The albumin:creatinine ratio was increased in both Ang II treatment groups (P<0.05; P<0.0001). The 1000 ng/kg per minute-treated fetuses were significantly smaller than vehicle treatment (P<0.001). Placental expression of Ang II receptors was increased in the junctional zone in 1000 ng/kg per minute Ang II-treated groups (P<0.05), with this zone showing depletion of glycogen content and structural abnormalities. Ang II infusion in pregnant stroke-prone spontaneously hypertensive rats mirrors hemodynamic, cardiac, and urinary profiles observed in preeclamptic women, with evidence of impaired fetal growth.

Associations of pregnancy complications with calculated cardiovascular disease risk and cardiovascular risk factors in middle age: the Avon Longitudinal Study of Parents and Children.

BACKGROUND: The nature and contribution of different pregnancy-related complications to future cardiovascular disease (CVD) and its risk factors and the mechanisms underlying these associations remain unclear. METHODS AND RESULTS: We studied associations of pregnancy diabetes mellitus, hypertensive disorders of pregnancy, preterm delivery, and size for gestational age with calculated 10-year CVD risk (based on the Framingham score) and a wide range of cardiovascular risk factors measured 18 years after pregnancy (mean age at outcome assessment, 48 years) in a prospective cohort of 3416 women. Gestational diabetes mellitus was positively associated with fasting glucose and insulin, even after adjustment for potential confounders, whereas hypertensive disorders of pregnancy were associated with body mass index, waist circumference, blood pressure, lipids, and insulin. Large for gestational age was associated with greater waist circumference and glucose concentrations, whereas small for gestational age and preterm delivery were associated with higher blood pressure. The association with the calculated 10-year CVD risk based on the Framingham prediction score was odds ratio 1.31 (95 confidence interval, 1.11-1.53) for preeclampsia and 1.26 (95 confidence interval, 0.95-1.68) for gestational diabetes mellitus compared with women without preeclampsia and without gestational diabetes mellitus, respectively. CONCLUSIONS: Hypertensive disorders of pregnancy and pregnancy diabetes mellitus are independently associated with an increased calculated 10-year CVD risk. Preeclampsia may be the better predictor of future CVD because it was associated with a wider range of cardiovascular risk factors. Our results suggest that pregnancy may be an important opportunity for early identification of women at increased risk of CVD later in life.

Genetic variants in microsomal epoxide hydrolase influence carbamazepine dosing.

OBJECTIVES: The dose of carbamazepine required to achieve optimal seizure control varies widely from patient to patient. We investigated polymorphic variants in various genes involved in the pharmacokinetics and pharmacodynamics of carbamazepine in an effort to identify predictors of maintenance dose. METHODS: : A total of 70 patients with epilepsy (49% were males; median age, 34 years; range, 14-72 years) who had benefited (>50% reduction in seizure frequency for at least 12 months) from treatment with carbamazepine monotherapy were included in the analysis. Known variants in drug-metabolizing enzyme genes, including those encoding cytochrome P450s, uridine 5'-diphosphate-glycosyltransferase, and microsomal epoxide hydrolase, together with a sodium channel polymorphism in SCN2A, were screened using polymerase chain reaction-restriction fragment length polymorphism or direct sequencing. Associations between demographic and genetic variables and carbamazepine dose were identified by univariate and multivariate regression analyses. RESULTS: All genotype frequencies were consistent with Hardy-Weinberg equilibrium (P > 0.05). No single demographic or genetic variable was of sufficient strength to independently influence carbamazepine dosing requirements. However, a multivariate model, incorporating patient age and specific genotypes (c.337T>C, c.416A>G) of the EPHX1 gene encoding microsomal epoxide hydrolase, revealed a significant association with the maintenance dose of carbamazepine (r(2) = 0.362, P= 0.002). CONCLUSIONS: This proof-of-principle study suggests that genetic variants in EPHX1 can be used to predict maintenance doses of carbamazepine. A large-scale prospective investigation of genetic influences on drug dosing strategies in epilepsy, with specific focus on whole gene variability for those proteins involved in the pharmacokinetics and pharmacodynamics of antiepileptic agents, is warranted.

Sodium valproate versus lamotrigine: a randomised comparison of efficacy, tolerability and effects on circulating androgenic hormones in newly diagnosed epilepsy.

We have performed a randomised, prospective study to compare the efficacy and tolerability of sodium valproate (VPA) and lamotrigine (LTG) monotherapy, and their effects on circulating androgenic hormones, in newly diagnosed epilepsy. A total of 225 patients (116 male; median age 35 years, range 13-80 years) were followed-up at 6-weekly intervals until they reached an end-point (12 months' seizure freedom; withdrawal due to intolerable side-effects; lack of efficacy despite adequate dosing). Twelve month seizure-free rates were identical (47%) in the VPA (n=111) and LTG (n=114) treatment arms. More patients taking VPA withdrew from the study due to adverse events (26 VPA versus 15 LTG; p=0.046). Eight patients, all taking VPA, dropped out during the first 6 months due to weight gain. There were no changes in mean serum concentrations of testosterone, sex-hormone binding globulin and androstenedione or in the free androgen index after 6 or 12 months' treatment with either drug in 112 patients who fulfilled the criteria for hormone analysis. No difference in efficacy was found between VPA and LTG in our patients with newly diagnosed epilepsy. LTG appeared to be better tolerated. Neither drug appeared to alter the circulating levels of androgenic hormones.

Screening tools for depressed mood after childbirth in UK-based South Asian women: a systematic review.

AIM: This paper is a report of a systematic review to answer the question: what is the relevance, acceptability, validity and effectiveness of tools designed to screen for postnatal depressed mood for South Asian women living in the UK? BACKGROUND: Standard methods to screen women for postnatal depressed mood were developed with Caucasian populations. This study reviews postnatal screening tools adapted or developed for United Kingdom-based South Asian women. METHOD: A structured systematic review of English language studies initially was completed between 1980 and May 2003, and later updated to January 2005. The review was based on an a priori search strategy with inclusion and exclusion criteria and analysis included a quality assessment tool. Findings were tabulated against criteria for acceptability and effectiveness of diagnostic tools. RESULTS: Seven papers were included in the review. None addressed all preset quality criteria. Four papers among them reported on translations of two existing tools (Edinburgh Postnatal Depression Scale and General Household Questionnaire). Two new tools were reported between the remaining three papers (Punjabi Postnatal Depression Scale and 'Doop Chaon'. Doop Chaon is a visual tool. The other tools used either Bengali or Punjabi, based on written scales. The General Household Questionnaire did not appear to be appropriate for this population. None of the studies were rigorous enough to demonstrate generalizable sensitivity or specificity. Qualitative data indicated that women preferred face-to-face interviews to self-complete questionnaires. CONCLUSIONS: None of the tools are currently sufficiently evaluated for clinical practice. Questions are raised specifically about use of language-based tools to measure postnatal depressed mood in this population and about the extent to which focused interviews could be used as an alternative for specific sub-sections of population groups.

Lack of association between the C3435T polymorphism in the human multidrug resistance (MDR1) gene and response to antiepileptic drug treatment.

PURPOSE: P-glycoprotein (P-gp) has been implicated in the causation of refractory epilepsy. The expression and efflux efficiency of P-gp is influenced by a polymorphism (C3435T) in the encoding gene (MDR1). Recent evidence suggests that the homozygous C-variant, which is associated with higher expression and increased activity of P-gp, is more common in patients with pharmacoresistant epilepsy. We have investigated the prevalence of this polymorphism in a series of patients attending a specialist epilepsy clinic. METHODS: DNA samples were obtained from 400 patients, irrespective of seizure type or drug treatment. Genotype of the C3435T polymorphism was determined by traditional polymerase chain reaction (PCR) followed by restriction digest. Classification of response to treatment was determined in a blinded fashion by an independent physician. Results were expressed as genotype and allele frequencies per response group and compared by logistic regression analysis. RESULTS: In total, 170 patients were classified as responders, with > or =12 months seizure freedom on current treatment. The remaining 230 patients were classified as nonresponders. Comparison of responders and nonresponders revealed no significant difference in allele frequency (C vs. T; odds ratio, 1.03; 95% CI, 0.78-1.37; p = 0.83) or genotype frequency (CC vs TT; odds ratio, 1.07; 95% CI, 0.60-1.91; p = 0.81). Subanalyses of individual seizure types were similarly unremarkable. CONCLUSIONS: This study failed to corroborate a previously reported association between the C3435T polymorphism in the human MDR1 gene and pharmacoresistant epilepsy. Whether the C3435T polymorphism can act as a marker for the natural history of treated epilepsy remains to be determined.

Pharmacodynamic interaction studies with topiramate in the pentylenetetrazol and maximal electroshock seizure models.

There is emerging evidence to support the efficacy of some antiepileptic drug (AED) combinations in refractory epilepsy. Definitive clinical studies are, however, difficult to perform. Experimental seizure models can be employed to identify potentially useful combinations for subsequent clinical evaluation. We have investigated the anticonvulsant effects of topiramate (TPM) in combination with 13 other AEDs in the pentylenetetrazol (PTZ) and maximal electroshock (MES) seizure models. Single drugs and combinations were administered by intraperitoneal injection and anticonvulsant effects determined at 1-hour post-dosing. TPM was without significant effect in the PTZ test. In contrast, phenobarbital, primidone, ethosuximide, sodium valproate, felbamate and tiagabine all increased the latency to the first generalised seizure. Combinations of TPM and active adjunctive drug were universally effective. Combinations of TPM with clobazam, lamotrigine and levetiracetam were also anticonvulsant, despite the inactivity of the constituent compounds when administered alone. TPM reduced the incidence of MES-induced seizures in a dose-dependent manner, as did phenobarbital, phenytoin, primidone, carbamazepine, sodium valproate, clobazam, lamotrigine, felbamate and tiagabine. All combination treatments were similarly effective. These findings suggest that combinations of TPM with lamotrigine and levetiracetam may demonstrate anticonvulsant synergism and merit further investigation in additional model systems and with recourse to more quantitative mathematical analysis.

Vigabatrin, but not gabapentin or topiramate, produces concentration-related effects on enzymes and intermediates of the GABA shunt in rat brain and retina.

PURPOSE: The antiepileptic drug (AED) vigabatrin (VGB), which exerts its pharmacologic effects on the gamma-aminobutyric acid (GABA) system, causes concentric visual field constriction in >40% of exposed adults. This may be a class effect of all agents with GABA-related mechanisms of action. We compared the concentration-related effects of VGB in rat brain and eye with those of gabapentin (GBP) and topiramate (TPM), both of which have been reported to elevate brain GABA concentrations in humans. METHODS: Adult male rats (n = 10) were administered 0.9% saline (control), VGB (250, 500, 1,000 mg/kg), GBP (50, 100, 200 mg/kg), or TPM (12.5, 25, 50, 100 mg/kg). At 2 h after dosing, animals were killed, a blood sample obtained, the brain dissected into eight distinct regions, and the retina and vitreous humor isolated from each eye. Samples were analyzed for several GABA-related neurochemical parameters, and serum and tissue drug concentrations determined. RESULTS: VGB treatment produced a significant (p < 0.05) dose-related increase in GABA concentrations and decrease in GABA-transaminase activity in all tissues investigated. This effect was most pronounced in the retina, where VGB concentrations were 18.5-fold higher than those in brain. In contrast, GBP and TPM were without effect on any of the neurochemical parameters investigated and did not accumulate appreciably in the retina. CONCLUSIONS: These findings corroborate a previously reported accumulation of VGB in the retina, which may be responsible for the visual field constriction observed clinically. This phenomenon does not appear to extend to other GABAergic drugs, suggesting that these agents might not cause visual field defects.

Differential expression of multidrug resistance genes in naïve rat brain.

The multidrug resistance (mdr1) gene family encodes the efflux transporter P-glycoprotein (P-gp) which contributes to the functionality of the blood-brain barrier. We have characterised the regional expression of mdr1 genes in nai;ve rat brain. Adult male Sprague-Dawley rats (n=6) were sacrificed and their brains rapidly removed. Seven distinct anatomical regions were isolated by microdissection and the expression of mdr1a and mdr1b determined by quantitative reverse-transcriptase polymerase chain reaction. The mdr1a isoform was expressed in all brain regions investigated, while mdr1b was expressed to a quantifiable degree in hippocampus alone. These findings reveal a differential expression of mdr1 genes in normal rodent brain tissue and suggest that P-gp may afford a broader protection of the hippocampus than other brain structures.

Regional expression of multidrug resistance genes in genetically epilepsy-prone rat brain after a single audiogenic seizure.

PURPOSE: The multidrug resistance (mdr) gene family encodes the drug transport macromolecule P-glycoprotein (P-gp), which contributes to the functionality of the blood-brain barrier. Recent evidence suggests that P-gp-mediated drug extrusion may play a facilitatory role in refractory epilepsy. We investigated the regional expression of mdr genes in genetically epilepsy-prone rat (GEPR) brain after a single audiogenic seizure. METHODS: Three groups of adult male GEPRs (n = 5/group) were exposed to a seizure-inducing audiogenic stimulus and killed at 4 h, 24 h, and 7 days thereafter. A further group (n = 5) served as a stimulus-naïve control. Expression of mdr1a and mdr1b in distinct anatomic brain regions (cortex, midbrain, pons/medulla, hippocampus) was determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in the presence of competitive internal standards. RESULTS: When compared with control, mdr1a expression in cortex and midbrain was significantly (p < 0.05) increased at 24 h after a single audiogenic seizure. Cortical mdr1a expression remained elevated at 7 days after stimulus. In contrast, mdr1a expression in pons/medulla and hippocampus was unchanged. The mdr1b isoform was quantifiable in hippocampus alone and not influenced by seizure activity. CONCLUSIONS: These findings suggest that acute seizures in the GEPR can induce the expression of mdr genes. The pattern of increased expression appears to follow the anatomic pathway of audiogenic seizures in these animals, with initiation in the midbrain and propagation to the cortex. Further studies are required to investigate the effects of recurrent seizure activity and to characterise mdr expression in other experimental seizure models.

P-glycoprotein-mediated efflux of antiepileptic drugs: preliminary studies in mdr1a knockout mice.

Evidence suggests that the efflux transporter P-glycoprotein (P-gp) may play a facilitatory role in refractory epilepsy by limiting the brain access of antiepileptic drugs (AEDs). We have conducted a preliminary pharmacokinetic study of seven commonly used AEDs in mdr1a knockout mice, devoid of P-gp at the blood-brain barrier. A parallel group of matched wild-type mice served as controls. AEDs were administered by subcutaneous injection and serum and brain drug concentrations determined at 30, 60, and 240min post-dosing. The brain-serum concentration ratio for topiramate was higher in mdr1a(-/-) mice than in wild-type controls at all time points investigated. No consistent effects were observed with any other AED investigated. These findings suggest that topiramate may be a substrate for P-gp-mediated transport. Further studies employing a range of model systems are required to substantiate this observation and to address the potential role of drug transporters in refractory epilepsy.