Effect of age at presentation on outcome following arthroscopic debridement of subchondral cystic lesions of the medial femoral condyle: 85 horses (1993-2003)

REASONS FOR PERFORMING STUDY

Subchondral cystic lesions of the medial femoral condyle (SCMFC) are well documented in horses < or =3 years; arthroscopic debridement or enucleation of the cyst is currently the surgical treatment of choice. However, studies of occurence and outcome following surgery in older horses are lacking.

OBJECTIVE

To identify factors important in outcome for horses with SCMFC treated by arthroscopic debridement.

HYPOTHESIS

Age of horse at presentation has a significant influence on return to work following arthroscopic treatment for SCMFC. Clinical and diagnostic findings are also significant with respect to prognosis.

METHODS

A retrospective review of medical records from 6 equine referral centres identified 85 horses that underwent arthroscopic debridement of SCMFC. Clinical examination, radiographic and arthroscopic findings were analysed together with follow-up data. Univariable analysis and multivariable logistic regression models were used to determine factors affecting return to soundness. Event-time analysis was performed to evaluate return to work.

RESULTS

Older horses (>3 years) were less likely to return to soundness (P = 0.02) or to work (P = 0.04) than younger horses (< or = 3 years). Of 39 horses age 0-3 years, 25 (64%, 95% CI 49-79%) returned to soundness. Of 46 horses age >3 years, 16 (35%,95% CI 21-49%) returned to soundness. In addition, cartilage damage at sites other than the SCMFC negatively affected prognosis (P = 0.05). The hospital where treatment was performed had no influence on return to soundness.

CONCLUSIONS

Older horses carry a worse prognosis for both return to soundness and return to work.

POTENTIAL RELEVANCE

It is important for clients to be made aware of the difference in outcome between age groups.

Novel pharmacogenetic markers for treatment outcome in azathioprine-treated inflammatory bowel disease

BACKGROUND

Azathioprine (AZA) pharmacogenetics are complex and much studied. Genetic polymorphism in TPMT is known to influence treatment outcome. Xanthine oxidase/dehydrogenase (XDH) and aldehyde oxidase (AO) compete with TPMT to inactivate AZA.

AIM

To assess whether genetic polymorphism in AOX1, XDH and MOCOS (the product of which activates the essential cofactor for AO and XDH) is associated with AZA treatment outcome in IBD.

METHODS

Real-time PCR was conducted for a panel of single nucleotide polymorphism (SNPs) in AOX1, XDH and MOCOS using TaqMan SNP genotyping assays in a prospective cohort of 192 patients receiving AZA for IBD.

RESULTS

Single nucleotide polymorphism AOX1 c.3404A > G (Asn1135Ser, rs55754655) predicted lack of AZA response (P = 0.035, OR 2.54, 95%CI 1.06-6.13) and when combined with TPMT activity, this information allowed stratification of a patient's chance of AZA response, ranging from 86% in patients where both markers were favourable to 33% where they were unfavourable (P < 0.0001). We also demonstrated a weak protective effect against adverse drug reactions (ADRs) from SNPs XDH c.837C > T (P = 0.048, OR 0.23, 95% CI 0.05-1.05) and MOCOS c.2107A > C, (P = 0.058 in recessive model, OR 0.64, 95%CI 0.36-1.15), which was stronger where they coincided (P = 0.019).

CONCLUSION

These findings have important implications for clinical practice and our understanding of AZA metabolism.

Predicting ischaemic stroke subtype from presenting systolic blood pressure: the BASIC Project

OBJECTIVE

We hypothesized that low presenting systolic blood pressure (SBP) predicted cardioembolic stroke aetiology.

DESIGN

Active and passive surveillance were used to identify all ischaemic strokes as part of the Brain Attack Surveillance in Corpus Christi (BASIC) population-based study. Multinomial logistic regression was used to examine the association between stroke subtype and first documented SBP in the medical record.

SETTING

Nueces County, TX, USA (313,645 residents in 2000). The community is urban with the majority of the population residing in the city of Corpus Christi. The area is served by seven adult acute care hospitals.

PATIENTS

Three hundred and eight cases with completed ischaemic stroke and determined subtype aetiology between January 2000 and December 2002.

RESULTS

Lower presenting SBP was associated with stroke subtype (P = 0.001). This association remained significant in the final model adjusted for age and history of coronary artery disease. The odds of cardioembolic versus small vessel occlusion increased by 20% (OR = 1.20, 95% CI: 1.07-1.35) for every 10 mmHg decrease in presenting SBP. Other covariates including race/ethnicity, gender, history of hypertension, and diabetes were neither significant predictors of stroke subtype, nor did they confound the association of SBP and stroke subtype. A 5 year increase in age increased the odds of cardioembolic subtype by 25% (OR = 1.25, 95% CI: 1.07-1.47).

CONCLUSIONS

Lower initial SBP and older age at ischaemic stroke presentation were associated with cardioembolic stroke. Suspicion of cardioembolic stroke should be increased in those presenting with low SBP.

Oxidative stress signaling in Alzheimer's disease

Multiple lines of evidence demonstrate that oxidative stress is an early event in Alzheimer's disease (AD), occurring prior to cytopathology, and therefore may play a key pathogenic role in AD. Oxidative stress not only temporally precedes the pathological lesions of the disease but also activates cell signaling pathways, which, in turn, contribute to lesion formation and, at the same time, provoke cellular responses such as compensatory upregulation of antioxidant enzymes found in vulnerable neurons in AD. In this review, we provide an overview of the evidence of oxidative stress and compensatory responses that occur in AD, particularly focused on potential sources of oxidative stress and the roles and mechanism of activation of stress-activated protein kinase pathways.

Genotypic Approaches to Therapy in Children (GATC): using information technology to improve drug safety

Adverse drug reactions (ADRs) are a major cause of morbidity and mortality in children. Current models of ADR surveillance have repeatedly demonstrated little pragmatic value to practicing clinicians. ADR reporting rates in the US and Canada suggest that only 5% of ADRs are reported. The Genotypic Approaches to Therapy in Children (GATC) network was established to identify and solve drug safety problems in paediatrics. We hypothesized that genetic polymorphisms underlie a significant portion of concentration-dependent ADRs in children. Our objective was to establish an ADR active surveillance network in paediatric hospitals across Canada. Surveillance clinicians evaluate clinical information from ADR cases and drug-matched controls, and collected DNA samples from all patients. The surveillance network will enable the identification of predictive genomic-markers for ADRs. With this knowledge, children at risk can be identified before therapy is initiated and enable personalized adjustments to therapy based on genetic make-up.

5-HT inhibition of rat insulin 2 promoter Cre recombinase transgene and proopiomelanocortin neuron excitability in the mouse arcuate nucleus

A number of anti-obesity agents have been developed that enhance hypothalamic 5-HT transmission. Various studies have demonstrated that arcuate neurons, which express proopiomelanocortin peptides (POMC neurons), and neuropeptide Y with agouti-related protein (NPY/AgRP) neurons, are components of the hypothalamic circuits responsible for energy homeostasis. An additional arcuate neuron population, rat insulin 2 promoter Cre recombinase transgene (RIPCre) neurons, has recently been implicated in hypothalamic melanocortin circuits involved in energy balance. It is currently unclear how 5-HT modifies neuron excitability in these local arcuate neuronal circuits. We show that 5-HT alters the excitability of the majority of mouse arcuate RIPCre neurons, by either hyperpolarization and inhibition or depolarization and excitation. RIPCre neurons sensitive to 5-HT, predominantly exhibit hyperpolarization and pharmacological studies indicate that inhibition of neuronal firing is likely to be through 5-HT_1F receptors increasing current through a voltage-dependent potassium conductance. Indeed, 5-HT_1F receptor immunoreactivity co-localizes with RIPCre green fluorescent protein expression. A minority population of POMC neurons also respond to 5-HT by hyperpolarization, and this appears to be mediated by the same receptor-channel mechanism. As neither POMC nor RIPCre neuronal populations display a common electrical response to 5-HT, this may indicate that sub-divisions of POMC and RIPCre neurons exist, perhaps serving different outputs.

Gender and ethnic differences in subarachnoid hemorrhage

BACKGROUND

Mexican Americans (MAs) comprise the largest component of the largest minority group within the United States. The purpose of this study was to examine ethnic and gender differences in the epidemiology, presentation, and outcomes after subarachnoid hemorrhage (SAH) in a representative United States community. Targeted public health interventions are dependent on accurate assessments of groups at highest disease risk.

METHODS

All patients with nontraumatic SAH older than 44 years were prospectively identified from January 1, 2000, to December 31, 2006, as part of the Brain Attack Surveillance In Corpus Christi project, an urban population-based study in southeast Texas. Risk ratios for cumulative SAH incidence comparing MAs with non Hispanic whites (NHWs) and women with men were calculated. Descriptive statistics for other clinical and demographic variables were computed overall, by gender, and by ethnicity.

RESULTS

A total of 107 patients had a SAH during the time period (7-year cumulative incidence: 11/10,000); of these, 43 were NHW (40% of cases vs 53% of the population) and 64 were MA (60% of cases vs 48% of the population). The overall age-adjusted risk ratio for SAH in MAs compared with NHWs was 1.67 (95% CI: 1.13, 2.47), and in women compared to men was 1.74 (95% CI 1.16, 2.62). Overall in-hospital mortality was 32.2%. No ethnic difference was observed for discharge disability or in-hospital mortality.

CONCLUSIONS

Subarachnoid hemorrhage disproportionately affects Mexican Americans and women. Public health interventions should target these groups to reduce the impact of this severe disease.

Neuronal death and survival under oxidative stress in Alzheimer and Parkinson diseases

Neuronal death is a common feature in neurodegenerative diseases including Alzheimer disease (AD) and Parkinson disease (PD). This occurs over years, not the minutes of classically defined apoptosis, and neurons show both responses of apoptosis and regeneration, evidenced by accumulated oxidative insult and attempts at cell cycle re-entry. There is recent evidence suggesting that several known gene mutations in causing familial AD (amyloid beta protein precursor, presenilin-1, or presenilin-2 gene) and familial PD (Parkin, PINK-1, or DJ-1 gene) are associated with increased oxidative stress. Also, several known genetic (e.g. Apolipoprotein Eepsilon4 variant) and environmental (e.g. metals or pesticides exposure) risk factors of sporadic AD and/or PD are associated with increased oxidative stress. In concord, patients at the preclinical stages of AD and PD as well as cellular and animal models of the diseases provide consistent evidence that oxidative insult is a significant early event in the pathological cascade of AD and PD. In contrast to the general aspects of the pathological hallmarks, aggregation of the disease-specific proteins such as amyloid-beta, tau, and alpha-synuclein may act as a compensatory (survival) response against the oxidative insult via the mechanism that the disease-specific structures sequester redox-active metals. Expanding knowledge of the molecular mechanisms of organism longevity indicates that pro-longevity gene products such as forkhead transcription factors and sirtuins are involved in the insulin-like signaling pathway and oxidative stress resistance against aging. An enhancement of the pro-longevity signaling (e.g. caloric restriction) may be a promising approach as anti-oxidative strategy against age-associated neurodegenerative diseases.

Rate measurements of the hydrolysis of complex organic macromolecules in cold aqueous solutions: implications for prebiotic chemistry on the early Earth and Titan

Organic macromolecules ("complex tholins") were synthesized from a 0.95 N(2)/0.05 CH(4) atmosphere in a high-voltage AC flow discharge reactor. When placed in liquid water, specific water soluble compounds in the macromolecules demonstrated Arrhenius type first order kinetics between 273 and 313 K and produced oxygenated organic species with activation energies in the range of approximately 60+/-10 kJ mol(-1). These reactions displayed half lives between 0.3 and 17 days at 273 K. Oxygen incorporation into such materials--a necessary step toward the formation of biological molecules--is therefore fast compared to processes that occur on geologic timescales, which include the freezing of impact melt pools and possible cryovolcanic sites on Saturn's organic-rich moon Titan.

Oxidative RNA damage and neurodegeneration

Although cellular RNA should be subject to the same oxidative insults as DNA and other cellular macromolecules, oxidative damage to RNA has not been a major focus in investigating the magnitude and the biological consequences of the free radical damage. However, because RNA is mostly single-stranded and its bases are not protected by hydrogen bonding and are less protected by specific proteins, RNA may be more susceptible to oxidative insults than DNA. Thereafter, oxidative damage to protein-coding RNA or non-coding RNA will potentially cause errors in proteins or dysregulation of gene expression. While less lethal than mutations in genome, such non-acutely lethal insults to cells might be associated with underlying mechanisms of several human diseases, especially chronic degeneration. Recently, oxidative RNA damage has been described in several neurodegenerative diseases including Alzheimer disease, Parkinson disease, dementia with Lewy bodies, and prion diseases. Of particular interest, oxidative RNA damage is a feature in vulnerable neurons at the very earliest-stages of these diseases, suggesting that RNA oxidation may actively contribute to the onset or to the development of disease. Mechanistically speaking, an increasing body of evidence suggests that the detrimental effects of oxidative RNA damage to protein synthesis are attenuated, at least in part, by the existence of mechanisms that avoid the incorporation of the damaged ribonucleotides into the translational machinery. Further investigations toward understanding of the consequences and processing mechanisms related to oxidative RNA damage may provide significant insights into the pathogenesis and therapeutic strategies for neurodegenerative and other degenerative diseases.

Integrin regulation of cytoplasmic calcium in excitatory neurons depends upon glutamate receptors and release from intracellular stores

Integrins regulate cytoplasmic calcium levels ([Ca(2+)]i) in various cell types but information on activities in neurons is limited. The issue is of current interest because of the evidence that both integrins and changes in [Ca(2+)]i are required for Long-Term Potentiation. Accordingly, the present studies evaluated integrin ligand effects in cortical neurons. Integrin ligands or alpha5beta1 integrin activating antisera rapidly increased [Ca(2+)]i with effects greater in glutamatergic than GABAergic neurons, absent in astroglia, and blocked by beta1 integrin neutralizing antisera and the tyrosine kinase antagonist genistein. Increases depended upon extracellular calcium and intracellular store release. Ligand-induced effects were reduced by voltage-sensitive calcium channel and NMDA receptor antagonists, but blocked by tetrodotoxin or AMPA receptor antagonists. These results indicate that integrin ligation triggers AMPA receptor/depolarization-dependent calcium influx followed by intracellular store release and suggest the possibility that integrin modulation of activity-induced changes in [Ca(2+)]i contributes importantly to lasting synaptic plasticity in forebrain neurons.

Neuronal binucleation in Alzheimer disease hippocampus

AIMS

The literature and teachings instruct that neurones in the adult brain are fully differentiated, quiescent cells that never divide. Somewhat surprisingly, and counter to such dogma, susceptible neurones in Alzheimer disease display an activated cell cycle phenotype. However, whether this leads to a coordinated procession through the cell cycle is unclear, particularly whether neurones enter anaphase and beyond. To begin to address this issue, in this study we sought to determine whether nuclear division occurs in these neurones.

METHODS

We examined a series of 101 archived, routinely stained hippocampal sections collected at post mortem for neuropathological evaluation for evidence of neuronal binucleation.

RESULTS

We report for the first time, binucleated neurones within the hippocampus in cases of Alzheimer disease but not in control cases (P < 0.05).

CONCLUSIONS

While a relatively rare event, occurring once every 20,000 neurones, this morphological evidence that neuronal cells within the cortical regions of the adult human brain in Alzheimer disease contain two nuclei supports the hypothesis that neuronal cells can re-enter into a coordinated cell cycle that culminates in nuclear division.

Causes of oxidative stress in Alzheimer disease

Oxidative stress is one of the earliest events of Alzheimer disease (AD), with implications as an important mediator in the onset, progression and pathogenesis of the disease. The generation of reactive oxygen species (ROS) and its consequent cellular damage/response contributes to much of the hallmark AD pathology seen in susceptible neurons. The sources of ROS-mediated damage appear to be multi-faceted in AD, with interactions between abnormal mitochondria, redox transition metals, and other factors. In this review, we provide an overview of these potential causes of oxidative stress in AD.

Conformational changes and cleavage of tau in Pick bodies parallel the early processing of tau found in Alzheimer pathology

Neuronal protein inclusions are a common feature in Alzheimer disease (AD) and Pick disease. Even though the inclusions are morphologically different, flame-shape structure for AD vs. spherical structure for Pick disease, both have filaments mainly composed of tau protein. In AD, a well-defined pattern of conformational changes and truncation has been described. In this study, we used laser scanning confocal microscopy to characterize and compare the processing of tau protein during Pick disease with that found in AD. We found that tau protein of Pick disease preserves most of the relevant epitopes found in AD, the conformational foldings labelled by Alz-50 and Tau-66, the cleavage sites D(421) and E(391), as well as many phosphorylated sites, such as Ser(199/202), Thr(205) and Ser(396/404). We found a strong pattern of association between phosphorylation and cleavage at site D(421), as well as the phosphorylation and the conformational Alz-50 epitope. When we used late AD markers such as the conformational Tau-66 epitope and MN423 (cleavage at site E(391)) in Pick bodies (PBs), the overlap was significantly less. Furthermore, following morphological quantification, we found significantly higher numbers of phosphorylated tau in PBs. Overall, our findings suggest that phosphorylation is an early event, likely preceding the cleavage of tau at D(421). Despite this consistency with AD, we found a major distinction, namely that PBs lack beta-sheet conformation. We propose a scheme of early tau processing in these structures, similar to neurofibrillary tangles of AD.

Mutant ubiquitin found in Alzheimer's disease causes neuritic beading of mitochondria in association with neuronal degeneration

A dinucleotide deletion in human ubiquitin (Ub) B messenger RNA leads to formation of polyubiquitin (UbB)+1, which has been implicated in neuronal cell death in Alzheimer's and other neurodegenerative diseases. Previous studies demonstrate that UbB+1 protein causes proteasome dysfunction. However, the molecular mechanism of UbB+1-mediated neuronal degeneration remains unknown. We now report that UbB+1 causes neuritic beading, impairment of mitochondrial movements, mitochondrial stress and neuronal degeneration in primary neurons. Transfection of UbB+1 induced a buildup of mitochondria in neurites and dysregulation of mitochondrial motor proteins, in particular, through detachment of P74, the dynein intermediate chain, from mitochondria and decreased mitochondria-microtubule interactions. Altered distribution of mitochondria was associated with activation of both the mitochondrial stress and p53 cell death pathways. These results support the hypothesis that neuritic clogging of mitochondria by UbB+1 triggers a cascade of events characterized by local activation of mitochondrial stress followed by global cell death. Furthermore, UbB+1 small interfering RNA efficiently blocked expression of UbB+1 protein, attenuated neuritic beading and preserved cellular morphology, suggesting a potential neuroprotective strategy for certain neurodegenerative disorders.

Early care limitations independently predict mortality after intracerebral hemorrhage

OBJECTIVE

Intracerebral hemorrhage (ICH) is associated with a high early mortality rate. We examined the impact of early do not resuscitate (DNR) orders and other limitations in aggressive care on mortality after ICH in a community-based study.

METHODS

Cases of spontaneous ICH from 2000 to 2003 were identified from the Brain Attack Surveillance in Corpus Christi (BASIC) project, with deaths ascertained through 2005. Charts were reviewed for early (<24 hours from presentation) DNR orders, withdrawal of care, or deferral of other life sustaining interventions, analyzed together as combined DNR (C-DNR). Multivariable Cox-proportional hazards models were used to examine the association between short- and long-term all-cause mortality and early C-DNR, adjusted for demographics and established predictors of mortality after ICH.

RESULTS

Of 18,393 subjects screened for cerebrovascular disease, 270 non-traumatic ICH cases were included. Cumulative mortality risk was 0.43 at 30 days and 0.55 over the study course. Early C-DNR was noted in 34% of cases and was associated with a doubling in the hazard of death both at 30 days (hazard ratio [HR] 2.17, 95% CI 1.38, 3.41) and at end of follow-up (HR 1.92, 95% CI 1.29, 2.87) despite adjustment for age, gender, ethnicity, Glasgow Coma Scale, ICH volume, intraventricular hemorrhage, and infratentorial hemorrhage.

CONCLUSIONS

Early care limitations are independently associated with both short- and long-term all-cause mortality after intracerebral hemorrhage (ICH) despite adjustment for expected predictors of ICH mortality. Physicians should carefully consider the effect of early limitations in aggressive care to avoid limiting care for patients who may survive their acute illness.

The effect of experience on detectability in local area anatomical noise

The aim of this study was to investigate if the ability to detect clinically relevant signals, within local area clinically relevant texture, is related to experience. A two alternative forced choice interleaved staircase experiment was conducted on 101 observers split into three groups; group 1 with diagnostic experience, group 2 with experience of imaging but not of making a diagnosis and group 3 with no experience of imaging. Thresholds of detection within synthesized, clinically representative textures were measured for a 15 mm simulated lesion within an MR T1 weighted brain texture and a 2.5 mm diameter simulated lesion embedded within X-ray trabecular bone texture. The results showed that there was a significant difference in threshold detectability between the groups for the brain texture at the 95% significance level but not for the bone texture. The experienced group did not demonstrate a correlation between their bone and brain results. However, the inexperienced group had a significant correlation between the bone and brain results. There was a significant correlation between increasing experience and detectability but this was dependent on the composition of the local area anatomical noise.

Neighborhood environment and risk of ischemic stroke: the brain attack surveillance in Corpus Christi (BASIC) Project

The authors explored whether neighborhood-level characteristics are associated with ischemic stroke and whether the association differs by ethnicity, age, and gender. Using data from the Brain Attack Surveillance in Corpus Christi Project (January 2000-June 2003), they identified cases of ischemic stroke (n = 1,247) from both hospital and out-of-hospital sources. Census tracts served as proxies for neighborhoods, and neighborhood socioeconomic status scores were constructed from census variables (higher scores represented less disadvantage). In Poisson regression analyses comparing the 90th percentile of neighborhood score with the 10th, the relative risk of stroke was 0.49 (95% confidence interval (CI): 0.41, 0.58). After adjustment for age, gender, and ethnicity, this association was attenuated (relative risk (RR) = 0.79, 95% CI: 0.63, 1.00). There was no ethnic difference in the association of score with stroke (p for interaction = 0.79). Significant effect modification was found for age (p for interaction < 0.001) and gender (p for interaction = 0.04), with increasing scores being protective against stroke in men and younger persons. Associations were attenuated after adjustment for education (men: RR = 0.77, 95% CI: 0.55, 1.07; persons aged <65 years: RR = 0.65, 95% CI: 0.41, 1.02). Neighborhood characteristics may influence stroke risk in certain gender and age groups. Mechanisms for these associations should be examined.

Projected costs of ischemic stroke in the United States

BACKGROUND

There are barriers to acute stroke care in minority groups as well as a higher incidence of ischemic stroke when compared with non-Hispanic whites.

OBJECTIVE

To estimate the future economic burden of stroke in non-Hispanic whites, Hispanics, and African Americans in the United States from 2005 to 2050.

METHODS

We used U.S. Census estimates of the race-ethnic group populations age 45 years and older. We obtained stroke epidemiology and service utilization data from the Northern Manhattan Stroke Study and the Brain Attack Surveillance in Corpus Christi project and other published data. We estimated costs directly from Medicare reimbursement or from studies that used Medicare reimbursement. Direct and indirect costs considered included ambulance services, initial hospitalization, rehabilitation, nursing home costs, outpatient clinic visits, drugs, informal caregiving, and potential lost earnings.

RESULTS

The total cost of stroke from 2005 to 2050, in 2005 dollars, is projected to be 1.52 trillion dollars for non-Hispanic whites, 313 billion dollars for Hispanics, and 379 billion dollars for African Americans. The per capita cost of stroke estimates are highest in African Americans (25,782 dollars), followed by Hispanics (17,201 dollars), and non-Hispanic whites (15,597 dollars). Loss of earnings is expected to be the highest cost contributor in each race-ethnic group.

CONCLUSIONS

The economic burden of stroke in African Americans and Hispanics will be enormous over the next several decades. Further efforts to improve stroke prevention and treatment in these high stroke risk groups are necessary.

Overprescribing of lipid lowering agents

BACKGROUND

Undertreatment of hyperlipidemia has received considerable attention. However, little is known about trends in overprescribing of lipid lowering agents. We examined these trends and their associations with physician, practice, and organisational factors.

METHODS

2034 physicians were surveyed twice: baseline (1996-7) and follow up (1998-9). On each occasion they were asked: "For what percentage of 50 year old men without other cardiac risk factors would you recommend an oral agent for total cholesterol of 240, LDL 150, and HDL 50 after 6 months on a low cholesterol diet?" During the survey period the National Cholesterol Education Program guidelines did not recommend prescribing for these patients. Binomial and multinomial logistic regressions assessed baseline overprescribing and longitudinal changes in overprescribing, accounting for complex sampling.

RESULTS

39% of physicians recommended prescribing at baseline (round 1), increasing at follow up (round 2) to 51% (p < 0.001). Physicians who were more likely to overprescribe at baseline were less likely to be board certified (odds ratio (OR) 0.49, 95% confidence interval (CI) 0.38 to 0.63; p < 0.001), were in solo or two-physician practices (OR 1.88, 95% CI 1.46 to 2.41; p < 0.001), had more revenue from Medicare (OR 1.10, 95% CI 1.03 to 1.17; p = 0.004) or Medicaid (OR 1.09, 95% CI 1.01 to 1.18; p = 0.03), or were family physicians (OR 1.87, 95% CI 1.35 to 2.58; p < 0.001). Physicians with large increases in overprescibing were more likely than those with small increases in overprescribing to be international medical graduates (OR 2.09, 95% CI 1.20 to 3.64; p = 0.011) and to spend more hours in patient care (OR 1.14, 95% CI 1.03 to 1.26; p = 0.016).

CONCLUSIONS

Overprescribing of lipid lowering agents is commonplace and increased. At baseline and longitudinally, overprescribing was primarily associated with physician and practice characteristics and not with organisational factors.

Trace copper levels in the drinking water, but not zinc or aluminum influence CNS Alzheimer-like pathology

Mounting evidence suggests copper may influence the progression of Alzheimer's disease by reducing clearance of the amyloid beta protein (Abeta) from the brain. Previous experiments show that addition of only 0.12 PPM copper (one-tenth the Environmental Protection Agency Human consumption limits) to distilled water was sufficient to precipitate the accumulation of Abeta in the brains of cholesterol-fed rabbits (1). Here we report that addition of copper to the drinking water of spontaneously hypercholesterolemic Watanabe rabbits, cholesterol-fed beagles and rabbits, PS1/APP transgenic mice produced significantly enhanced brain levels of Abeta. In contrast to the effects of copper, we found that aluminum- or zinc-ion-supplemented distilled water did not have a significant effect on brain Ab accumulation in cholesterol-fed rabbits. We also report that administration of distilled water produced a reduction in the expected accumulation of Ab in three separate animal models. Collectively, these data suggest that water quality may have a significant influence on disease progression and Ab neuropathology in AD.

Ultrastructural analysis of a murine model of congenital hydrocephalus produced by overexpression of transforming growth factor-beta1 in the central nervous system

The purpose of this study was to elucidate using transmission electron microscopy (TEM) the ultrastructural changes that occur within the cortical gray matter of a novel reproducible model of congenital hydrocephalus in mice created to overexpress the cytokine transforming growth factor-beta1 (TGF-beta1) in the central nervous system. Brain tissue was obtained from mice from a colony engineered to overexpress TGF-beta1 at two days postpartum and compared to a wild-type aged-matched control. This tissue was fixed using a solution containing 1.25% paraformaldehyde and 1.25% glutaraldehyde in phosphate buffer at least 3-4 h and then cut into 40-50 microm sections. Randomly selected thin sections were stained with uranyl acetate and lead citrate, and then analyzed using a JEOL-100CX or 1200EX transmission electron microscope at accelerating voltage 80 kV. Dramatic neuronal and glial pathology was observed throughout the cortical neuropil in TGF-beta1 mice. The most striking change in the hydrocephalic mice was severe edema with extracellular fluid, possibly due to cerebrospinal fluid (CSF) penetration into the cortex. In addition, severe disruption of the cytoplasmic matrix was seen throughout the cortex, with damage to cellular organelles and particularly severe damage to mitochondria. Our results suggest that congenital hydrocephalus may be associated with significant damage to cortical tissue.

Differences in intracerebral hemorrhage between Mexican Americans and non-Hispanic whites

BACKGROUND

Mexican Americans (MAs) have higher incidence rates of intracerebral hemorrhage (ICH) than non-Hispanic whites (NHWs). The authors present clinical and imaging characteristics of ICH in MAs and NHWs in a population-based study.

METHODS

This work is part of the Brain Attack Surveillance in Corpus Christi (BASIC) project. Cases of nontraumatic ICH were identified from 2000 to 2003. Multivariable logistic regression was used to assess the independent associations between ethnicity and ICH location (lobar vs nonlobar) and volume (> or = 30 vs < 30 mL), adjusting for demographics and baseline clinical characteristics. Logistic regression was also used to determine the association between ethnicity and in-hospital mortality, adjusting for confounders.

RESULTS

A total of 149 MAs and 111 NHWs with ICH were identified. MAs were younger (70 vs 77, p < 0.001), more often male (55% vs 42%, p = 0.04), had a lower prevalence of atrial fibrillation (2.0% vs 13%, p < 0.001), and a higher prevalence of diabetes (39% vs 19%, p < 0.001). MA ethnicity was independently associated with nonlobar hemorrhage (OR 2.08, 95% CI: 1.15, 3.70). MAs had over two times the odds of having small (< 30 mL) hemorrhages compared with NHWs (OR = 2.41, 95% CI: 1.31, 4.46). NHWs had higher in-hospital mortality, though this association was no longer significant after adjustment for ICH volume, location, age, and sex.

CONCLUSIONS

There are significant differences in the characteristics of ICH in MAs and NHWs, with MA patients more likely to have smaller, nonlobar hemorrhages. These differences may be used to examine the underlying pathophysiology of ICH.

Differential induction of PPAR-gamma by luminal glutamine and iNOS by luminal arginine in the rodent postischemic small bowel

Using a rodent model of gut ischemia-reperfusion (I/R), we have previously shown that the induction of inducible nitric oxide synthase (iNOS) is harmful, whereas the induction of heme oxygenase 1 (HO-1) and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is protective. In the present study, we hypothesized that the luminal nutrients arginine and glutamine differentially modulate these molecular events in the postischemic gut. Jejunal sacs were created in rats at laparotomy, filled with either 60 mM glutamine, arginine, or magnesium sulfate (osmotic control) followed by 60 min of superior mesenteric artery occlusion and 6 h of reperfusion, and compared with shams. The jejunum was harvested for histology or myeloperoxidase (MPO) activity (inflammation). Heat shock proteins and iNOS were quantitated by Western blot analysis and PPAR-gamma by DNA binding activity. In some experiments, rats were pretreated with the PPAR-gamma inhibitor G9662 or with the iNOS inhibitor N-[3(aminomethyl)benzyl]acetamidine (1400W). iNOS was significantly increased by arginine but not by glutamine following gut I/R and was associated with increased MPO activity and mucosal injury. On the other hand, PPAR-gamma was significantly increased by glutamine but decreased by arginine, whereas heat shock proteins were similarly increased in all experimental groups. The PPAR-gamma inhibitor G9662 abrogated the protective effects of glutamine, whereas the iNOS inhibitor 1400W attenuated the injurious effects of arginine. We concluded that luminal arginine and glutamine differentially modulate the molecular events that regulate injurious I/R-mediated gut inflammation and injury. The induction of PPAR-gamma by luminal glutamine is a novel protective mechanism, whereas luminal arginine appears harmful to the postischemic gut due to enhanced expression of iNOS.

Presentation of intracerebral haemorrhage in a community

BACKGROUND

Studies on intracerebral haemorrhage (ICH) from tertiary care centres may not be an accurate representation of the true spectrum of disease presentation.

OBJECTIVE

To describe the clinical and imaging presentation of ICH in a community devoid of the referral bias of an academic medical centre; and to investigate factors associated with lower Glasgow coma scale (GCS) score at presentation, as GCS is crucial to early clinical decision making.

METHODS

The study formed part of the BASIC project (Brain Attack Surveillance in Corpus Christi), a population based stroke surveillance study in a bi-ethnic Texas community. Cases of first non-traumatic ICH were identified from years 2000 to 2003, using active and passive surveillance. Clinical data were collected from medical records by trained abstractors, and all computed tomography (CT) scans were reviewed by a study physician. Multivariable linear regression was used to identify clinical and CT predictors of a lower GCS score.

RESULTS

260 cases of non-traumatic ICH were identified. Median ICH volume was 11 ml (interquartile range 3 to 36) with hydrocephalus noted in 45%. Median initial GCS score was 12.5 (7 to 15). Hydrocephalus score (p = 0.0014), ambient cistern effacement (p = 0.0002), ICH volume (p = 0.014), and female sex (p = 0.024) were independently associated with lower GCS score at presentation, adjusting for other variables.

CONCLUSIONS

ICH has a wide range of severity at presentation. Hydrocephalus is a potentially reversible cause of a lower GCS score. Since early withdrawal of care decisions are often based on initial GCS, recognition of the important influence of hydrocephalus on GCS is warranted before withdrawal of care decisions are made.

Effect of fat content on infection by Listeria monocytogenes in a mouse model

An estimated 2,500 cases of listeriosis occur annually in the United States. Listeriosis is particularly severe among pregnant women and immunocompromised individuals. Little is known regarding the effect of the food matrix on the ability of L. monocytogenes to survive in the gastrointestinal tract and cause systemic infection. Mice were inoculated with various doses of L. monocytogenes in skim milk, Half & Half, or whipping cream to determine whether differences in milk fat content influence the ability of L. monocytogenes to survive passage through the gut and infect the liver or spleen. The number of fecal samples positive for L. monocytogenes increased with increasing doses of L. monocytogenes for all three vehicles. The number of L. monocytogenes cells isolated from liver or spleen of mice dosed with L. monocytogenes was not significantly different among treatment vehicles. Dose-response models revealed that as the dosage of L. monocytogenes was increased in different milk vehicles, the number of L. monocytogenes cells in liver or spleen also increased. Although fat content of food had no dose-dependent effect on L. monocytogenes infection in the murine gastrointestinal tract, we cannot discount the possibility that it may be a factor in L. monocytogenes infections of humans because of differences in the physiology of gastrointestinal tracts of mice and humans.

A scoring system for ascertainment of incident stroke; the Risk Index Score (RISc)

OBJECTIVES

The main objective of this study was to develop and validate a computer-based statistical algorithm that could be translated into a simple scoring system in order to ascertain incident stroke cases using hospital admission medical records data.

METHODS

The Risk Index Score (RISc) algorithm was developed using data collected prospectively by the Brain Attack Surveillance in Corpus Christi (BASIC) project, 2000. The validity of RISc was evaluated by estimating the concordance of scoring system stroke ascertainment to stroke ascertainment by physician and/or abstractor review of hospital admission records.

RESULTS

RISc was developed on 1718 randomly selected patients (training set) and then statistically validated on an independent sample of 858 patients (validation set). A multivariable logistic model was used to develop RISc and subsequently evaluated by goodness-of-fit and receiver operating characteristic (ROC) analyses. The higher the value of RISc, the higher the patient's risk of potential stroke. The study showed RISc was well calibrated and discriminated those who had potential stroke from those that did not on initial screening.

CONCLUSION

In this study we developed and validated a rapid, easy, efficient, and accurate method to ascertain incident stroke cases from routine hospital admission records for epidemiologic investigations. Validation of this scoring system was achieved statistically; however, clinical validation in a community hospital setting is warranted.

Brain and brawn: Parallels in oxidative strength

Neuronal oxidative stress occurs early in the progression of Alzheimer disease (AD), significantly before the development of the pathologic hallmarks, neurofibrillary tangles, and senile plaques. Study of Down syndrome, cases with autosomal dominant mutation, and sporadic AD all suggest amyloid-beta deposition and hyperphosphorylated tau function as compensatory responses and downstream adaptations to ensure that neuronal cells do not succumb to oxidative damage. Amyloid-beta and tau hyperphosphorylation also define vulnerable muscle cells in sporadic inclusion-body myositis (s-IBM). The role of the structural changes of s-IBM, as in AD, remains to be determined but may mark a critical response yielding a novel balance in oxidant homeostasis.

Evaluation of the clinical efficacy of prokinetic drugs in the management of post-operative ileus: Can retrospective data help us?

The objectives of the study were to determine whether retrospective data can be used to answer questions about the efficacy of prokinetic agents when used to treat horses with post-operative ileus (POI). We describe prevalence and mortality of POI with reference to treatment with four prokinetic agents. By combining data from two Hospitals a study population of 55 horses with POI following pedunculated lipoma obstruction (PLO) was established. Univariable and multivariable associations were determined between short term survival and potential explanatory variables. With death as outcome in multivariable models, breed and hospital were significantly associated with outcome but the use of prokinetic agents was not (P=0.15). However, sample size estimates indicate the low power of this study to detect differences in outcome. It was not possible definitively to evaluate the efficacy of prokinetics as treatment for POI following PLO using retrospective data. The data were suggestive of limited efficacy of prokinetics as treatment for POI. It is postulated that the identified association between hospital and survival reflects differences in clinician decision making. The study highlights the need for further prospective studies using randomised clinical trials to evaluate accurately the efficacy of prokinetic agents. This report illustrates difficulties with performing retrospective analysis of clinical data to determine the efficacy of treatment regimes.

Emergency department evaluation of ischemic stroke and TIA: the BASIC Project

OBJECTIVE

To identify demographic and clinical variables of emergency department (ED) practices in a community-based acute stroke study.

METHODS

By both active and passive surveillance, the authors identified cerebrovascular disease cases in Nueces County, TX, as part of the Brain Attack Surveillance in Corpus Christi (BASIC) Project, a population-based stroke surveillance study, between January 1, 2000, and December 31, 2002. With use of multivariable logistic regression, variables independently associated with three separate outcomes were sought: hospital admission, brain imaging in the ED, and neurologist consultation in the ED. Prespecified variables included age, sex, ethnicity, insurance status, NIH Stroke Scale score, type of stroke (ischemic stroke or TIA), vascular risk factors, and symptom presentation variables. Percentage use of recombinant tissue plasminogen activator (rt-PA) was calculated.

RESULTS

A total of 941 Mexican Americans (MAs) and 855 non-Hispanic whites (NHWs) were seen for ischemic stroke (66%) or TIA (34%). Only 8% of patients received an in-person neurology consultation in the ED, and 12% did not receive any head imaging. TIA was negatively associated with neurology consultations compared with completed stroke (odds ratio [OR] 0.35 [95% CI 0.21 to 0.57]). TIA (OR 0.14 [0.10 to 0.19]) and sensory symptoms (OR 0.59 [0.44 to 0.81]) were also negatively associated with hospital admission. MAs (OR 0.58 [0.35 to 0.98]) were less likely to have neurology consultations in the ED than NHWs. Only 1.7% of patients were treated with rt-PA.

CONCLUSIONS

Neurologists are seldom involved with acute cerebrovascular care in the emergency department (ED), especially in patients with TIA. Greater neurologist involvement may improve acute stroke diagnosis and treatment efforts in the ED.

Dissociation and ionization of H+2 by ultrashort intense laser pulses probed by coincidence 3D momentum imaging

Laser-induced dissociation and ionization of H(+)(2) were simultaneously measured using coincidence 3D momentum imaging, allowing direct separation of the two processes, even where the fragment kinetic energy is the same for both processes. The results for 45 and 135 fs 790 nm pulses with an intensity of approximately 2.5 x 10(14) W/cm(2) differ from each other much more than one would expect from previous measurements with longer pulses. Ionization was negligible for the longer pulse and was strongly aligned along the laser polarization for the shorter pulse, but showed no structure in its kinetic energy distribution. In addition, the ionization to dissociation ratio was found to be much smaller than theoretically predicted for H(+)(2).

Soft tissue sarcomas: are current referral guidelines sufficient?

INTRODUCTION

To investigate the adequacy of current early referral guidelines for patients with extremity soft tissue sarcomas.

PATIENTS & METHODS

365 patients with confirmed soft tissue sarcomas were evaluated. Data were collected prospectively and included the length of history and the presence of features in current guidelines suggestive of malignancy (pain, rapidity of growth, depth and tumour size). Statistical analysis included the t-test, ANOVA and the Chi test.

RESULTS

Deep tumours were the commonest (306 patients with deep tumours). Pain was the least consistent feature (176 patients with pain). 345 patients with one or more of the guideline features had an average history of 19.86 months, 238 of these were seen after more than 3 months.

CONCLUSION

Although the majority of soft tissue sarcomas in our patients had one or more of the clinical guideline features, there was still an unacceptable delay in referring these patients to a specialist unit. The referral guidelines should be modified with special emphasis on depth, which is the most sensitive, followed by size and a history of rapid growth. This combined with increased awareness of these guidelines and a well-advertised, open-access clinic linked to a specialist unit should allow for a more rapid evaluation of soft tissue tumours.

No Increase in Rejection or Graft Loss in Kidney Transplant Recipients With Thrombophilia Treated With Anticoagulation and Triple Immunosuppression

INTRODUCTION

Recent studies from Europe have demonstrated that patients with end-stage renal disease who receive a kidney transplant are at an increased risk for rejection and graft loss when compared with patients who have no known thrombophilia. The role of anticoagulation has not been investigated in these patients.

MATERIALS AND METHODS

We prospectively tested patients who were evaluated for a kidney transplant for 8 thrombophilias, protein S and C deficiencies, factor V Leiden mutation, antithrombin III deficiency, anticardiolipin antibody, lupus anticoagulant, prothrombin gene mutation, and heparin-induced platelet antibody (HIPA). Patients with any identified thrombophilia received heparin or argatroban (for HIPA (+) patients) followed by coumadin for 1 year after transplantation. Triple therapy included cyclosporine, prednisone, and CellCept (Roche Pharmaceuticals, Nutley, NJ, USA). Sensitized, black, or repeat transplantation patients received induction with an interleukin (IL)-2 inhibitor. Data were collected in a retrospective manner. Rejection was biopsy-proven.

RESULTS

Of the 112 transplant recipients who were tested for thrombophilia, 37 had 1 or more thrombophilia and 75 had no thrombophilia identified. Twenty-six patients received heparin and 11 received argatroban. There were no differences in recipient age, cold storage time, graft loss, HLA match, rejection episodes, 1-year graft survival, or serum creatinine level at 1 year. Significant differences were noted in posttransplantation bleeding, 35% versus 5%, and delayed graft function, 32% versus 15%, in patients with thrombophilia versus no thrombophilia, respectively.

CONCLUSION

This is the first study to demonstrate that there is no increase in rejection or graft loss in kidney transplant recipients with thrombophilia when treated with anticoagulation and triple immunosuppression.

Effects of x-ray irradiation on material properties

With a new commercial sterilisation technique about to enter the market, this article details a study that compared the effects of existing electron-beam irradiation with X-ray irradiation on different types of plastics commonly used in the manufacture of medical devices. The results are evaluated here.

Evaluation of the dosimetric performance of BANG3® polymer gel

New radiotherapy techniques call for three-dimensional dosimetric methods with high spatial resolution. Radiation sensitive gels read out using MRI T(2) mapping provide an extremely promising option, and commercially available BANG polymer gels provide a convenient route into gel dosimetry. Gel dosimetry is dependent on the ability to calibrate gel response against radiation dose. This in turn is dependent on the reproducibility of response both between gels irradiated to the same dose and for a single gel sample over time. This study aims to evaluate the performance of a commercially available BANG gel. Our experimental arrangement gave excellent precision of radiation delivery (<0.2%) and reproducibility of T(2) measurement (<0.5%). Seven groups of 10 test tubes containing BANG3 gel were irradiated in 0.5 Gy steps between 0 and 3 Gy. A further four groups of four samples were irradiated in 2 Gy steps between 4 and 10 Gy. The gel samples were identical and derived from the same manufacturing batch. MR imaging was carried out four days after irradiation and then at weekly intervals for four weeks. Short-term variation in gel response can readily be corrected using reference samples. Longer term systematic drift of the gel calibration curve was observed relative to reference samples prepared in-house for quality assurance purposes. This implies that read-out of the calibration gels and dosimetry phantom must be performed at the same time after irradiation, or errors of up to 25% may be incurred. Precision of gel response did not change significantly over time. The observation of significantly different T(2) values both prior to irradiation and following irradiation to the same dose (variation up to 15%) illustrates the current difficulties associated with BANG3 gel calibration and constrains the practical utility of these commercially available gels for clinical radiation dosimetry.

Evidence for the role of gonadotropin hormones in the development of Alzheimer disease

Differences in the prevalence and age of onset of Alzheimer disease (AD) in men and women, and observations that hormone replacement therapy (HRT) may prevent the development of AD, caused many to hypothesize that estrogen deficiency contributes to AD. However, recent trials using estrogen failed to show any benefit in preventing or alleviating the disease. To address this and other inconsistencies in the estrogen hypothesis, we suspect that another hormone of the hypothalamic-pituitary-gonadal axis, luteinizing hormone (LH), as a major factor in AD pathogenesis. Individuals with AD have elevated levels of LH when compared with controls, and both LH and its receptor are present in increased quantities in brain regions susceptible to degeneration in AD. LH is also known to be mitogenic, and could therefore initiate the cell cycle abnormalities known to be present in AD-affected neurons. In cell culture, LH increases amyloidogenic processing of amyloid-beta protein precursor, and in animal models of AD, pharmacologic suppression of LH and FSH reduces plaque formation. Given the evidence supporting a pathogenic role for LH in AD, a trial of leuprolide acetate, which suppresses LH release, has been initiated in patients.

Ischemic stroke subtypes among Mexican Americans and non-Hispanic whites: the BASIC Project

Ischemic stroke subtype distribution was compared between Mexican Americans (MAs) and non-Hispanic whites (NHWs) in a community-based stroke surveillance study in Nueces County, TX. There was no difference in the distribution of stroke subtype by ethnicity (p = 0.19). There was a similar proportion of small-vessel and large-artery strokes between the two ethnic groups (p = 0.32). Differences in stroke rates among MAs and NHWs are not explained by the distribution of ischemic stroke subtypes.

Proliferative responses observed following vancomycin treatment in renal proximal tubule epithelial cells

Vancomycin (VAN) is a glycopeptide antibiotic used to treat gram-positive infections. Nephrotoxicity is a common side effect observed with vancomycin therapy. However, the mechanism of vancomycin-induced nephrotoxicity has not been fully characterized. In this study we examined the effect of vancomycin on cellular proliferation in renal proximal tubule cells. A dose- and time-dependent increase in cell number and total cellular protein was observed following vancomycin exposure. Vancomycin exposure also caused an increase in BrdU incorporation followed by the accumulation of renal proximal tubule cells in G(2)/M phase of the cell cycle. These effects were inhibited by pretreatment with the mitogen-activated protein kinase inhibitor, PD098059, suggesting an association between the cell proliferative effect of VAN and the induction of the mitogen-activated protein kinase signaling pathway. Mitochondrial function in renal proximal tubule cells was assessed using oxygen consumption and ATP concentrations. We observed an increase in oxygen consumption and ATP concentrations following short-term exposure to vancomycin. Together, our data suggest that vancomycin treatment produces alterations in mitochondrial function that coincide with a cell proliferative response in renal proximal tubule epithelial cells.

beta-Site APP cleaving enzyme up-regulation induced by 4-hydroxynonenal is mediated by stress-activated protein kinases pathways

4-Hydroxynonenal (HNE), an aldehydic product of lipid peroxidation, up-regulates expression of the beta-site APP cleaving enzyme (BACE-1), an aspartyl protease responsible for the beta-secretase cleavage of amyloid precursor protein (AbetaPP), and results in increased levels of amyloid beta (Abeta) peptide. The mechanisms underlying this remain unclear but are of fundamental importance because prevention of BACE-1 up-regulation is viewed as an important therapeutic strategy. In this study, we exposed NT(2) neurons to a range of HNE concentrations (0.5-5 microm) that elicited an up-regulation of BACE-1 expression, a significant increase in intracellular and secreted levels of Abeta peptides as well as apoptosis involving poly-ADP ribose polymerase cleavage and activation of caspase 3. To delineate the molecular events involved in HNE-mediated BACE-1 activation, we investigated the involvement of stress-activated protein kinases (SAPK), signal transducers and activators of transcription (STAT) and serine-threonine kinase B/phosphatidylinositol phosphate 3 kinase (Akt/PtdIns3K). Using specific pharmacological inhibitors, our results show that activation of c-Jun N-terminal kinases and p38(MAPK.), but not STAT or Akt/PtdIns3K, pathways mediate the HNE-dependent up-regulation of BACE-1 expression. Therefore, HNE, an oxidative stress mediator detected in vivo in the brains of Alzheimer's disease patients, may play a pathogenetic role in Alzheimer's disease by selectively activating SAPK pathways and BACE-1 that regulate the proteolytic processing of AbetaPP.

Neurofilament proteins in neurodegenerative diseases

The function of neurofilaments, the major component in large myelinated neurons, is not well understood even though they were discovered as structures over 100 years ago. Recent studies have suggested that neuro-filaments are closely related to many neurodegenerative diseases, such as amyotrophic lateral sclerosis, Parkinson disease Alzheimer disease, and diabetes. Using in vitro assays, cultures and transgenic mice, these studies provided new insights into neurofilament function. The function of each subunit, the relationship of neurofilaments with other cytoskeletal elements and their clinical significance are topics of increasing attention.

Retinoic acid isomers protect hippocampal neurons from amyloid-beta induced neurodegeneration

Attenuating amyloid-beta mediated neurodegeneration is of major therapeutic consideration in the potential treatment of Alzheimer disease. Previously, we found that a high dietary consumption of retinoic acid was associated with a reduced incidence of Alzheimer disease. Therefore, in this study, we investigated whether amyloid-beta mediated cell death in primary hippocampal neurons could be prevented by retinoic acid isomers. Our results suggest that retinoic acid isomers, including all-trans retinoic acid, 9-cis retinoic acid, and 13-cis retinoic acid, may play an important role in protecting neurons from amyloid-beta -induced cell death. Retinoic acid may therefore afford a novel therapeutic mechanism for the treatment and prevention of Alzheimer disease.

Oxidative stress mechanisms and potential therapeutics in Alzheimer disease

Oxidative damage of biological macromolecules is a hallmark of most neurodegenerative disorders such as Alzheimer, Parkinson and diffuse Lewy body diseases. Another important phenomenon involved in these disorders is the alteration of iron and copper homeostasis. Data from the literature support the involvement of metal homeostasis in mitochondrial dysfunction, protein alterations and nucleic acid damage which are relevant in brain function and consequently, in the development of neurodegenerative disorders. Although alterations in transition metal homeostasis, redox activity, and localization are well documented, it must be determined how alterations of specific copper- and iron-containing metalloenzymes are also involved in Alzheimer disease. The clarification of these phenomena can open a new window for understanding the mechanisms underlying neurodegeneration and, consequently, for the development of new therapeutic strategies such as gene therapy and new pharmaceutical formulations with antioxidant and chelating properties.

Phylogeography of Bufo fowleri at its northern range limit

Many of the species that recolonized previously glaciated areas in the Great Lakes basin of North America over the past 10-12,000 years exhibit genetic evidence of multiple invasion routes and present-day secondary contact between deeply divergent lineages. With this in mind, we investigated the phylogeographical structure of genetic variability in Fowler's toads (Bufo fowleri) at the northern edge of its distribution where its range encircles the Lake Erie basin. Because B. fowleri is so closely tied to habitats along the Lake Erie shoreline, we would expect to find clear evidence of the number of invasions leading to the species' colonization of the northern shore. A 540 bp sequence from the mitochondrial control region was amplified and analysed for 158 individuals from 21 populations. Interpopulation sequence variation ranged from 0% to 6%. Phylogenetic analysis of p-distance using the neighbor-joining method revealed two deeply divergent (6% sequence divergence) mtDNA lineages (Phylogroup 1 and 2), possibly arising as a result of secondary contact of populations that entered the region from two separate glacial refugia. However, the phylogeographical pattern was not simple. The populations at Long Point, on the north shore of Lake Erie, clustered with the population from Indiana Dunes on Lake Michigan to form Phylogroup 2 whereas all other B. fowleri populations examined from both sides of Lake Erie constituted Phylogroup 1. Furthermore, mtDNA sequences from the related species Bufo americanus, obtained from populations outside the range of B. fowleri, clustered with mtDNA haplotypes of B. fowleri Phylogroup 1, indicating the possibility of partial introgression of mitochondria from one species to the other.

TNF-α expression patterns as potential molecular biomarker for human skin cells exposed to vesicant chemical warfare agents: sulfur mustard (HD) and Lewisite (L)

Studies were conducted to examine the effect of two vesicant chemical warfare agents (VCWA), one of them an arsenical, on cytokine gene expression in normal human epidermal keratinocyte (NHEK) cells. We tested 2,2'-dichlorethylsulfide (sulfur mustard, military designation HD) and 2,chlorovinyldichloroarsine (Lewisite, military designation L), which have significant differences in their chemical, physical, and toxicological properties. Human tumor necrosis factor-alpha (hTNF-alpha) cytokine was detected by using the enzyme-linked immunosorbent assay, a protein multiplex immunoassay, Luminex100, and reverse transcription-polymerase chain reaction (RT-PCR). The messenger RNA expression of hTNF-alpha was determined to provide a semi-quantitative analysis. HD-stimulated NHEK induced secretion of hTNF-alpha in a dose-dependent manner. Dose response effect of Lewisite decreased hTNF-alpha levels. Time-response data indicated that the maximum response for HD occurred at 24 h with an associated cytotoxic concentration of 10(-4) mol/L. NHEK cells stimulated with 10(-4) mol/L HD for 24 h at 37 degrees C increased detectable levels of hTNF-alpha from 5 to 28 ng/ml at an index of cell viability between 85 to 93% as detected by Luminex100. Our results indicated that the increased levels of hTNF-alpha by HD are dependent on the primary cultures, cell densities, and chemical properties of the stimulation. Lewisite under the same conditions as HD caused a reduction of hTNF-alpha from control levels of 1.5 ng/ml to 0.3 ng/ml after stimulation (10(-4) mol/L), with an index of cell viability of reverse similar 34%. We analyzed the transcriptional of hTNF-alpha gene and found that HD (10(-6) to 10(-4) mol/L) activates hTNF-alpha gene in cultured NHEK and that L at 10(-6) to 10(-4) mol/L markedly reduces hTNF-alpha gene. We conclude that the pro-inflammatory mediator, hTNF-alpha, could be a potential biomarker for differentiating between exposure of HD or L.

Hypoxia tolerance in mammalian heterotherms

Heterothermic mammals tolerate severe hypoxia, as well as a variety of central nervous system insults, better than homeothermic mammals. Tolerance to hypoxia may stem from adaptations associated with the ability to survive hibernation and periodic arousal thermogenesis. Here, we review evidence and mechanisms of hypoxia tolerance during hibernation, euthermy and arousal in heterothermic mammals and consider potential mechanisms for regenerative-like processes, such as synaptogenesis, observed within hours of hypoxic stress associated with arousal thermogenesis.