Fine-mapping the MHC locus in juvenile idiopathic arthritis (JIA) reveals genetic heterogeneity corresponding to distinct adult inflammatory arthritic diseases.

OBJECTIVES: Juvenile idiopathic arthritis (JIA) is a heterogeneous group of diseases, comprising seven categories. Genetic data could potentially be used to help redefine JIA categories and improve the current classification system. The human leucocyte antigen (HLA) region is strongly associated with JIA. Fine-mapping of the region was performed to look for similarities and differences in HLA associations between the JIA categories and define correspondences with adult inflammatory arthritides. METHODS: Dense genotype data from the HLA region, from the Immunochip array for 5043 JIA cases and 14 390 controls, were used to impute single-nucleotide polymorphisms, HLA classical alleles and amino acids. Bivariate analysis was performed to investigate genetic correlation between the JIA categories. Conditional analysis was used to identify additional effects within the region. Comparison of the findings with those in adult inflammatory arthritic diseases was performed. RESULTS: We identified category-specific associations and have demonstrated for the first time that rheumatoid factor (RF)-negative polyarticular JIA and oligoarticular JIA are genetically similar in their HLA associations. We also observe that each JIA category potentially has an adult counterpart. The RF-positive polyarthritis association at HLA-DRB1 amino acid at position 13 mirrors the association in adult seropositive rheumatoid arthritis (RA). Interestingly, the combined oligoarthritis and RF-negative polyarthritis dataset shares the same association with adult seronegative RA. CONCLUSIONS: The findings suggest the value of using genetic data in helping to classify the categories of this heterogeneous disease. Mapping JIA categories to adult counterparts could enable shared knowledge of disease pathogenesis and aetiology and facilitate transition from paediatric to adult services.

Identification of loci associated with late-onset psoriasis using dense genotyping of immune-related regions.

BACKGROUND: Chronic plaque psoriasis can be subdivided into two groups according to the age of onset: type 1 (early onset, before 40 years) and type 2 (late onset, at or beyond 40 years). So far, 36 genetic loci have been associated with early-onset psoriasis in genome-wide association studies of white populations, while few studies have investigated genetic susceptibility to late-onset psoriasis. OBJECTIVES: To characterize the genetics underpinning late-onset psoriasis. METHODS: We genotyped 543 cases of late-onset psoriasis and 4373 healthy controls using the Immunochip array, a dense genotyping chip containing single-nucleotide polymorphisms previously associated with autoimmune diseases. Imputation using SNP2HLA and stepwise logistic regression analysis was performed for markers spanning the human leucocyte antigen gene region. RESULTS: Two loci (HLA-C and IL12B) previously associated with early-onset psoriasis showed significant association at a genome-wide threshold in the current study (P < 5 × 10(-8)). Six more loci (TRAF3IP2, IL23R, RNF114, IFIH1, IL23A and HLA-A) showed study-wide significant association (P < 2·3 × 10(-5); calculated using Genetic type 1 error calculator). Additionally, we identified an association at IL1R1 on chromosome 2q13, which is not associated with early-onset disease. CONCLUSIONS: This is the largest study to date of genetic loci in late-onset psoriasis, and demonstrates the overlap that exists with early-onset psoriasis. It also suggests that some loci are associated exclusively with late-onset psoriasis.

Predicting changes in cardiac myocyte contractility during early drug discovery with in vitro assays.

Cardiovascular-related adverse drug effects are a major concern for the pharmaceutical industry. Activity of an investigational drug at the L-type calcium channel could manifest in a number of ways, including changes in cardiac contractility. The aim of this study was to define which of the two assay technologies - radioligand-binding or automated electrophysiology - was most predictive of contractility effects in an in vitro myocyte contractility assay. The activity of reference and proprietary compounds at the L-type calcium channel was measured by radioligand-binding assays, conventional patch-clamp, automated electrophysiology, and by measurement of contractility in canine isolated cardiac myocytes. Activity in the radioligand-binding assay at the L-type Ca channel phenylalkylamine binding site was most predictive of an inotropic effect in the canine cardiac myocyte assay. The sensitivity was 73%, specificity 83% and predictivity 78%. The radioligand-binding assay may be run at a single test concentration and potency estimated. The least predictive assay was automated electrophysiology which showed a significant bias when compared with other assay formats. Given the importance of the L-type calcium channel, not just in cardiac function, but also in other organ systems, a screening strategy emerges whereby single concentration ligand-binding can be performed early in the discovery process with sufficient predictivity, throughput and turnaround time to influence chemical design and address a significant safety-related liability, at relatively low cost.

Enrichment of vitamin D response elements in RA-associated loci supports a role for vitamin D in the pathogenesis of RA.

The aim of this study was to explore the role of vitamin D in rheumatoid arthritis (RA) pathogenesis by investigating the enrichment of vitamin D response elements (VDREs) in confirmed RA susceptibility loci and testing variants associated with vitamin D levels for association with RA. Bioinformatically, VDRE genomic positions were overlaid with non-HLA (human leukocyte antigen)-confirmed RA susceptibility regions. The number of VDREs at RA loci was compared to a randomly selected set of genomic loci to calculate an average relative risk (RR). Single-nucleotide polymorphisms (SNPs) in the DHCR7/NADSYN1 (nicotinamide adenine dinucleotide synthase 1) and CYP2R1 loci, previously associated with circulating vitamin D levels, were tested in UK RA cases (n=3870) and controls (n=8430). Significant enrichment of VDREs was seen at RA loci (P=9.23 × 10(-8)) when regions were defined either by gene (RR 5.50) or position (RR 5.86). SNPs in the DHCR7/NADSYN1 locus showed evidence of positive association with RA, rs4944076 (P=0.008, odds ratio (OR) 1.14, 95% confidence interval (CI) 1.03-1.24). The significant enrichment of VDREs at RA-associated loci and the modest association of variants in loci-controlling levels of circulating vitamin D supports the hypothesis that vitamin D has a role in the development of RA.

MTHFR gene polymorphisms and outcome of methotrexate treatment in patients with rheumatoid arthritis: analysis of key polymorphisms and meta-analysis of C677T and A1298C polymorphisms.

Association of two key variants mapping to the MTHFR gene (C677T (rs1801133) and A1298C (rs1801131)) with response to methotrexate (MTX) remains controversial. We investigated these and other markers spanning the gene as predictors of MTX efficacy and adverse events in a UK rheumatoid arthritis (RA) patient cohort and performed a meta-analysis of the two key variants using all published data. The tagging single nucleotide polymorphisms (SNPs) were genotyped in 309 patients with well-defined outcomes to MTX treatment and 17 studies were included in the meta-analysis. No association of the SNPs tested was detected with MTX efficacy or toxicity in our UK cohort. After combining our data with previous studies by meta-analysis, the random effects pooled odds ratios (OR) for both C677T and A1298C showed no association with efficacy or toxicity for either of the SNPs (efficacy: OR=1.05 (95% confidence interval (CI) 0.83-1.32) and OR=0.81 (95% CI 0.53-1.24), respectively; toxicity: OR=1.38 (95% CI 0.90-2.12) and OR=1.19 (95% CI 0.80-1.78), respectively). The available evidence suggests that the MTHFR C677T and A1298C gene polymorphisms are not reliable predictors of response to MTX treatment in RA patients.

An investigation of rheumatoid arthritis loci in patients with early-onset psoriasis validates association of the REL gene.

BACKGROUND: Phenotypically diverse autoimmune conditions share common genetic susceptibility loci and underlying molecular pathways. OBJECTIVES: By systematically searching for single nucleotide polymorphisms (SNPs) associated with another autoimmune disease, rheumatoid arthritis (RA), we aimed to elucidate novel genetic markers of psoriasis. METHODS: We investigated 18 SNPs, previously confirmed as being associated with RA, in a U.K. cohort of 623 patients with early-onset psoriasis (presenting before age 40 years), comparing them with 2662 control subjects. RESULTS: Our findings confirm the association of early-onset psoriasis with REL (rs13031237, P=0·0027). The minor allele of REL had opposing effects upon susceptibility to disease in patients with psoriasis and RA. CONCLUSION: Similar exploration of additional autoimmune loci and fine mapping of such regions may provide further insight into the genetics and molecular pathophysiology of psoriasis.

Genetic susceptibility to psoriasis and psoriatic arthritis: implications for therapy.

The era of genome-wide association studies has revolutionized the search for genetic susceptibility loci in complex genetic conditions such as psoriasis. There are currently 16 loci with confirmed evidence for association with psoriasis susceptibility but there is the potential for more to be discovered as the genetic heritability of the disease has not yet been fully explained. Many of the associated loci overlap with those for psoriatic arthritis. In contrast to psoriasis susceptibility, few studies have been performed to identify predictors of drug response in psoriasis. As large-scale collaborations and registries for psoriasis and psoriatic arthritis are established, it is likely that a genome-wide approach may be used as a more effective method of searching for genetic predictors of treatment response. However, candidate gene studies will still have a role; for example, it is likely that some disease susceptibility genes will also be markers of treatment response, based on evidence from other diseases. This review summarizes recent advances in investigating the role genetics plays in psoriasis susceptibility and contrasts these to advances made in psoriatic arthritis. Further, it describes the genetics of treatment response in the two diseases and indicates how susceptibility loci could be used to identify drug response in the future.

Examining the overlap between genome-wide rare variant association signals and linkage peaks in rheumatoid arthritis.

OBJECTIVE: With the exception of the major histocompatibility complex (MHC) and STAT4, no other rheumatoid arthritis (RA) linkage peak has been successfully fine-mapped to date. This apparent failure to identify association under peaks of linkage could be ascribed to the examination of common variation, when linkage is likely to be driven by rare variants. The purpose of this study was to investigate the overlap between genome-wide rare variant RA association signals observed in the Wellcome Trust Case Control Consortium (WTCCC) study and 11 replicating RA linkage peaks, defined as regions with evidence for linkage in >1 study. METHODS: The WTCCC data set contained 40,482 variants with minor allele frequency of ≤0.05 in 1,860 RA patients and 2,938 controls. Genotypes of all rare variants within a given gene region were collapsed into a single locus and a global P value was calculated per gene. RESULTS: The distribution of rare variant signals (association P≤10(-5)) was found to differ significantly between regions with and without linkage evidence (P=2×10(-17) by Fisher's exact test). No significant difference was observed after data from the MHC region were removed or when the effect of the HLA-DRB1 locus was accounted for. CONCLUSION: The results suggest that rare variant association signals are significantly overrepresented under linkage peaks in RA, but the effect is driven by the MHC. This is the first study to examine the overlap between linkage peaks and rare variant association signals genome-wide in a complex disease.

Information and professional support: key factors in the provision of family-centred early childhood intervention services.

BACKGROUND: Much has been written on the principles of family-centred practice and on the service delivery methods and skills required of its practitioners. Far less has been written from the perspective of families whose children have a disability. The aims of this study were twofold: firstly to understand families' experiences of family-centred early childhood intervention services and secondly to explore other factors that might impact on these experiences. METHODS: One hundred and thirty families attending two established early childhood intervention services in New South Wales, Australia completed a survey incorporating the Measure of Processes of Care-56, the Family Empowerment Scale, the Family Support Scale and the Parenting Daily Hassles Scale. RESULTS: Consistent with previous research using the Measure of Processes of Care-56, 'respectful and supportive care' was the domain of care families rated to occur most and 'provision of general information' was the domain they rated to occur least. Significant positive relationships existed between families' ratings of family-centred care and feelings of empowerment. Being provided with general information was strongly correlated with family empowerment. Families' social support networks played an important role but support from professionals was most strongly correlated with families' experiences of family-centred care. Finally, families whose children's early intervention services were co-ordinated by a professional experienced significantly better care. CONCLUSIONS: The provision of general information and professional support are key components of family-centred early childhood intervention services.

A systematic investigation of confirmed autoimmune loci in early-onset psoriasis reveals an association with IL2/IL21.

BACKGROUND: Many autoimmune diseases share common susceptibility loci suggesting similar underlying cellular mechanisms involved in disease expression. OBJECTIVES: The purpose of this investigation was to study 21 genetic variants in 14 genes that are confirmed autoimmune loci in a cohort of patients with early-onset psoriasis. METHODS: Patients with early-onset psoriasis (n = 750) and controls (n = 3531) were genotyped using the Sequenom(®) MassArray™ iPLEX Gold platform. RESULTS: We found strong evidence of association with two variants in the IL2/IL21 (rs6822844, genotypic P = 3·3 × 10(-4) ; rs2069778, genotypic P = 7·86 × 10(-4)) region. CONCLUSIONS: The findings, although requiring replication, suggest that IL2/IL21 may play a key role in the pathogenesis of psoriasis as well as in other diverse autoimmune diseases.

Population genetic screening efficiently identifies carriers of autosomal dominant diseases.

Three inherited autosomal dominant conditions-BRCA-related hereditary breast and ovarian cancer (HBOC), Lynch syndrome (LS) and familial hypercholesterolemia (FH)-have been termed the Centers for Disease Control and Prevention Tier 1 (CDCT1) genetic conditions, for which early identification and intervention have a meaningful potential for clinical actionability and a positive impact on public health1. In typical medical practice, genetic testing for these conditions is based on personal or family history, ethnic background or other demographic characteristics2. In this study of a cohort of 26,906 participants in the Healthy Nevada Project (HNP), we first evaluated whether population screening could efficiently identify carriers of these genetic conditions and, second, we evaluated the impact of genetic risk on health outcomes for these participants. We found a 1.33% combined carrier rate for pathogenic and likely pathogenic (P/LP) genetic variants for HBOC, LS and FH. Of these carriers, 21.9% of participants had clinically relevant disease, among whom 70% had been diagnosed with relevant disease before age 65. Moreover, 90% of the risk carriers had not been previously identified, and less than 19.8% of these had documentation in their medical records of inherited genetic disease risk, including family history. In a direct follow-up survey with all carriers, only 25.2% of individuals reported a family history of relevant disease. Our experience with the HNP suggests that genetic screening in patients could identify at-risk carriers, who would not be otherwise identified in routine care.

Recent advances in the genetics of RA susceptibility.

RA is a common autoimmune disease with a complex aetiology in which genetic and environmental factors contribute to disease. The genetic component of RA is largely undefined and, up until very recently, there were only two reproducible associations. The strongest of these associations is of genes within the HLA region, particularly the HLA-DRB1 gene. A second, more modest, association identified has been of the protein tyrosine phosphatase non-receptor 22 (PTPN22) gene. Advances in genotyping technology have facilitated the application of whole genome association approaches to identify disease causal variants. This, coupled with the availability of large case and control collections has enabled the identification of low-to-moderate risk loci. These newer study designs combined with traditional linkage and association studies have accelerated the identification of novel risk loci. The past few months alone have witnessed the identification of three new RA risk loci. In this review, we aim to give an update on recent progress in RA genetics, focusing mainly on the identification of novel loci.

Association of Toll-like receptor 4 (TLR4) with chronic plaque type psoriasis and psoriatic arthritis.

Family studies have provided overwhelming evidence for an underlying genetic component to psoriasis. Toll-like receptors (TLRs) are key transmembrane proteins in both the innate and adaptive immune responses which are known to be integral processes in psoriasis. Recent functional studies support this notion having suggested a role for TLR4 in the pathogenesis of psoriasis. Furthermore a missense polymorphism in the TLR4 gene has been associated with a number of autoimmune conditions, including Crohn diseases, making TLR4 a viable candidate gene for investigation. The aim of this study was to investigate polymorphisms across the TLR4 region with a high-density single nucleotide polymorphism (SNP) panel in a large cohort of patients with chronic plaque type psoriasis. Twenty SNPs were successfully genotyped using Sequenom iPLEX Gold platform in 2826 UK chronic plaque type psoriasis patients including subgroup data on presence of confirmed psoriatic arthritis (n = 1839) and early-onset psoriasis (n = 1466) was available. Allele frequencies for psoriasis patients were compared against imputed Wellcome Trust Case Control Consortium controls (n = 4861). Significant association was observed between a missense variant rs4986790 of TLR4 (Asp229Gly) and plaque type psoriasis (p = 2 × 10(-4)) which was also notable in those with psoriatic arthritis (p = 2 × 10(-4)) and early-onset psoriasis (p = 8 × 10(-4)). We present data suggestive of an association between a functional variant and an intronic variant of TLR4 and chronic plaque type psoriasis and psoriatic arthritis. However, validation of this association in independent cohorts will be necessary.

Binary oscillations in the rate of reoxidation of the primary acceptor of photosystem II.

The decay of fluorescence yield following each of a series of saturating laser flashes has been used to monitor the kinetics of reoxidation of the primary acceptor of Photosystem II under conditions of varied redox potential. 1. In dark-adapted chloroplasts, a damped binary oscillation as a function of flash number was observed in the kinetics of the decay of the fluorescence yield. The decay was faster on odd than on even-numbered flashes. 2. In the presence of low concentrations of 1,4-benzoquinone, the oscillation was more marked, and over the range approx 200--350 mV, independent of redox potential. The decay following flash 1 under these conditions had a half-time of approx. 200--400 microseconds. The decay following flash 2 was decelerated; the initial rate was up to 10-fold slower than after flash 1. 3. We suggest that the kinetics following a single flash reflect the rate of the reaction Q-B leads to QB-, and following the second flash, Q-B- leads to QB2-. Benzoquinone at low concentrations oxidises a residual fraction of B- which is usually reduced in the dark before the flash sequence. 4. A faster component in the decay (t u/2 approximately 140 microseconds) following the first flash titrated in over the range Eh greater than 350 mV. The binary oscillation was still apparent but delayed by one flash. 5. We discuss the relative redox potentials of the couples B/B- and B-/B2-, and the role of the component which titrates in at Eh greater than 350 mV.

A high potential acceptor for photosystem II.

The effects of ferricyanide on Photosystem II reactions have been investigated by measurements of microsecond and millisecond prompt fluorescence and microsecond-delayed fluorescence in dark-adapted chloroplasts: (1) Titrations using ferri-ferrocyanide mixtures on: (a) the fast phase of the increase in fluorescence yield observed during a xenon flash, and (b) the normalised area above the millisecond fluorescence induction curve for chloroplasts inhibited by DCMU, showed a pH dependent mid point potential of 400 mV at pH 7.0 which varied by approx. -60 mV/pH unit between pH 6 and 8.5. (2) A saturating laser flash induced a fluorescence increase (as monitored by a weak measuring beam) of only 50% of that reached following a second flash in chloroplasts preincubated with ferricyanide and inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) prior to illumination. In the absence of ferricyanide, the fluorescence level reached after a single flash was initially close to that measured after a second flash (although the level subsequently declined). (3) The initial amplitude of the microsecond-delayed fluorescence excited by a single laser flash was diminished in chloroplasts dark-adapted with ferricyanide. In the presence of DCMU and ferricyanide, the amplitude was also diminished for the first flash of a series, but subsequently enhanced above the level obtained in chloroplasts in the presence of DCMU alone. (4) The above effects were not seen if DCMU was added to the chloroplasts before ferricyanide, or if the period of incubation with ferricyanide was much less than 4 min. (5) These results suggested the presence of a second acceptor Q2, with Em7 = 400 mV and n = 1, before the DCMU block in Photosystem II. There is 0.35--1 equivalent of the acceptor per reaction centre, and its reduction occurs within less than 5 mus. The role of the acceptor in double turnovers of the photochemistry during a single flash and its likely operating redox potential are discussed.

Effects of pH on reactions on the donor side of photosystem II.

The effects of pH on the increase of fluorescence yield measured in the microsecond range, and on the microsecond delayed fluorescence have been studied in dark adapted chloroplasts as a function of flash number. (1) At pH 7, the amplitude of the fast-phase of the microsecond fluorescence yield rise oscillated as a function of flash number with period 4 and with maxima on flashes 1 and 5, and minima on flashes 3 and 7. The damped oscillations were apparent over the range between 6 and 8, although the absolute amplitude of the fast phase was diminished at the lower end of the range. At pH 4, there was no fast phase in the rise and, at pH 9, an enhanced fast-phase occurred only for the first flash. (2) The decay of microsecond delayed fluorescence was described by the sum of exponentials with half-times of 10--15 mus and 40--50 mus. Over the pH range 6- less than 8, the extrapolated initial amplitude and the proportion of the change due to the faster component showed oscillations which were opposite in phase to those observed for the prompt fluorescence yield rise; the slower component showed weaker oscillations of the same phase. At pH 4, there were no oscillations and the slow phase predominated. At pH 9, the delayed fluorescence intensity was diminished on the first flash, and high on subsequent flashes. (3) The results are interpreted in terms of a model in which protons are released during all transitions of the S-states with the exception of S1 leads to S2, and in which ther are two sites of inhibition on the donor side of the photo-system at extreme pH values. At pH 4, electron donation to P+ occurs with a half-time approx. 135 mus, either by a back reaction from Q-, or from D; electron transport is interrupted between Z1 and P. At pH 9, electron transport is inhibited between Z1 and Z2; rapid re-reduction of P+ by Z1 occurs after 1 flash, and on subsequent flashes electrons from D, an alternative donor reduce P+. The location of the positive charge on states S2 and S3 is discussed.

Inhibitors of poly (ADP-ribose) synthetase protect rat cardiomyocytes against oxidant stress.

OBJECTIVE: Inhibitors of poly (ADP-ribose) synthetase (PARS) activity reduce the infarct size caused by regional myocardial ischaemia and reperfusion in the rabbit and rat in vivo. The mechanism of action of these inhibitors is unclear. Here we investigate the effects of the PARS inhibitor 3-aminobenzamide (3-AB) on infarct size caused by ischaemia and reperfusion of the isolated, perfused heart of the rat. We also investigate the role of PARS in the hydrogen peroxide-mediated cell injury/necrosis in rat cardiac myoblasts. METHODS: Rat isolated hearts perfused at constant pressure (80 mmHg) were subjected to 35 min of regional ischaemia and 2 h of reperfusion. Infarct size was determined at the end of the experiment using nitro-blue tetrazolium. 3-AB (300 microM) or 3-aminobenzoic acid (3-ABA, 300 microM) were infused during the reperfusion period. Rat cardiac myoblasts (H9c2 cells) were preincubated with the PARS inhibitors, 3-AB. nicotinamide (Nic) or 1,5-dihydroxyisoquinoline (ISO) or the inactive analogues 3-ABA or nicotinic acid (NicA) prior to exposure with hydrogen peroxide (1 mM). Cell injury was assessed by measuring mitochondrial respiration and cell necrosis by measuring the release of LDH. PARS activity was determined by measuring the incorporation of NAD into nuclear proteins. RESULTS: Regional ischaemia and reperfusion of the isolated rat heart resulted in an infarct size of 54% which was reduced by 3-AB, but not by 3-ABA. Exposure of rat cardiac myoblasts to hydrogen peroxide caused an increase in PARS activity and cell injury/necrosis which was attenuated by pretreatment with the PARS inhibitors. CONCLUSION: Inhibition of the activity of PARS attenuates the cell death associated with oxidant stress in rat cardiac myoblasts and heart.

Depression in recently bereaved prepubertal children.

OBJECTIVE: The purpose of this study was to ascertain depressive symptoms in recently bereaved prepubertal children and compare these symptoms with those of depressed prepubertal children. METHOD: The subjects were 38 children who had recently experienced the death of one but not both of their parents. They had to meet strict inclusion criteria so that the effects of bereavement per se, rather than other significant stressors, could be assessed. The comparison group consisted of 38 hospitalized, depressed children individually matched to each bereaved subject for age, sex, and socioeconomic status. All of the children underwent systematic and comprehensive evaluation. They and their parents were independently evaluated by trained interviewers using the parent and child versions of the Diagnostic Interview for Children and Adolescents. Family histories and basic demographic information were also obtained. RESULTS: The recently bereaved children endorsed many depressive symptoms. Thirty-seven percent of them met the DSM-III-R criteria for a major depressive episode. The depressed children, however, had more depressive symptoms on average than the bereaved children. The factors associated with increased depressive symptoms in the bereaved children were 1) the mother as the surviving parent, 2) preexisting untreated psychiatric disorder in the child, 3) family history of depression, and 4) high socioeconomic status. CONCLUSIONS: A considerable number of the bereaved children developed the clinical symptoms of a major depressive episode immediately after the death of a parent. The relation of these symptoms to the subsequent course of grief and to major depressive disorder remains unknown and should be studied further.

Tempol reduces infarct size in rodent models of regional myocardial ischemia and reperfusion.

Reactive oxygen species (ROS) contribute to ischemia-reperfusion injury of the heart. This study investigates the effects of tempol, a membrane-permeable radical scavenger on (i) the infarct size caused by regional myocardial ischemia and reperfusion of the heart in vivo (rat, rabbit) and in vitro (rat), and (ii) the cell injury caused by hydrogen peroxide (H2O2) in rat cardiac myoblasts (H9c2 cells). In the anesthetized rat, tempol reduced the infarct size caused by regional myocardial ischemia (25 min) and reperfusion (2 h) from 60 +/- 3% (control, n = 8) to 24 +/- 5% (n = 6, p < .05). In the anesthetized rabbit, tempol also attenuated the infarct size caused by myocardial ischemia (45 min) and reperfusion (2 h) from 59 +/- 3% (control, n = 6) to 39 +/- 5% (n = 5, p < .05). Regional ischemia (35 min) and reperfusion (2 h) of the isolated, buffer-perfused heart of the rat resulted in an infarct size of 54 +/- 4% (control n = 7). Reperfusion of hearts with buffer containing tempol (n = 6) caused a 37% reduction in infarct size (n = 6, p < .05). Pretreatment of rat cardiac myoblasts with tempol attenuated the impairment in mitochondrial respiration caused by H2O2 (1 mM for 4 h). Thus, the membrane-permeable radical scavenger tempol reduces myocardial infarct size in rodents.

Effects of lorazepam on rate of forgetting, on retrieval from semantic memory and on manual dexterity.

Using a double-blind procedure, 16 out of 32 volunteer subjects (students) each took 2.5 mg of lorazepam (Ativan) orally and the remainder took a placebo. To overcome the problem of wide variation in individual tolerance to the drug, impairment on a task unrelated to memory (a manual dexterity task) was used to divide drug subjects into a group appreciably affected by the drug, subgroup 1, and a group minimally affected, subgroup 2. Only subgroup 1 showed consistent impairment of episodic memory. Both subgroups showed some impairment in a semantic memory task (generation of words from a specified category), but this was confined to the rate at which the task was carried out. The main aim of the experiment was to examine the effect of lorazepam on the rate of forgetting of word lists when drug and control subjects' initial recall levels were equalized. There was no evidence that the drug affected rate of forgetting: this suggests that it does not affect retention. There was also no evidence that it affected retrieval, since there was no impairment in the recall of material presented before administration of the drug. Hence its locus of action is attributed to input, specifically to impaired encoding of contextual information.