Seven cases of surgical native valve endocarditis caused by coagulase-negative staphylococci: An underappreciated disease

BACKGROUND

Native valve endocarditis caused by coagulase-negative staphylococci is uncommon and the diagnosis is infrequently considered. The disease, however, appears to be increasing in frequency and can pursue an aggressive clinical course. We report the clinical features of 7 cases of coagulase-negative staphylococcal native valve endocarditis (CNS-NVE) seen at 1 institution with a large cardiovascular referral base over a 10-month period. All cases required valve replacement surgery.

METHODS

Clinical history, echocardiograms, and microbiologic and histopathologic data were reviewed for 7 patients with surgical CNS-NVE.

RESULTS

Four patients had intravenous central catheters, and 1 had recent surgery, whereas the remaining 2 had no identifiable risk factors. Presentations ranged from subacute (4 cases) to acute with complications (3 cases). Complications included congestive heart failure, stroke, and heart block. Echocardiography demonstrated valvular lesions in all 7 cases. Valve pathologic study demonstrated gram-positive cocci in all 7 cases; blood cultures grew coagulase-negative staphylococci in 6 cases and valve cultures grew Staphylococcus epidermidis in 5 cases.

CONCLUSIONS

Coagulase-negative staphylococci, including S epidermidis, can cause severe native valve endocarditis requiring valve replacement. The increasing use of intravascular access devices in the community may herald an increase in the incidence of CNS-NVE. A high index of diagnostic suspicion in the appropriate clinical setting is critical for optimal management.

Activation of MKK6, an upstream activator of p38, in Alzheimer's disease

Mitogen-activated protein kinase (MAPK) p38 has been implicated in the pathogenesis of Alzheimer's disease, but the upstream cascade leading to p38 activation has not been elucidated in the disease. In the present study, we focused on mitogen-activated protein kinase kinase 6 (MKK6), one of the upstream activators of p38 MAPK. We found that MKK6 was not only increased but also specifically associated with granular structures in the susceptible neurons in the hippocampus and cortex of Alzheimer's disease patients, but was only weakly diffuse in the cytoplasm in neurons in control cases. Immunoblot analysis demonstrated a significant increase of MKK6 level in Alzheimer's disease compared with age-matched controls. In this regard, in hippocampal and cortical regions of individuals with Alzheimer's disease, the activated phospho-MKK6 was localized exclusively in association with pathological alterations including neurofibrillary tangles, senile plaques, neuropil threads and granular structures, overlapping with activated p38 MAPK suggesting both a functional and mechanic link. By immunoblot analysis, phospho-MKK6 is also significantly increased in AD compared with control cases. Together, these findings lend further credence to the notion that the p38 MAPK pathway is dysregulated in Alzheimer's disease and also indicates an active role for this pathway in disease pathogenesis.

Self-organizing task modules and explicit coordinate systems in a neural network model for 3-D saccades

The goal of this study was to train an artificial neural network to generate accurate saccades in Listing's plane and then determine how the hidden units performed the visuomotor transformation. A three-layer neural network was successfully trained, using back-prop, to take in oculocentric retinal error vectors and three-dimensional eye orientation and to generate the correct head-centric motor error vector within Listing's plane. Analysis of the hidden layer of trained networks showed that explicit representations of desired target direction and eye orientation were not employed. Instead, the hidden-layer units consistently divided themselves into four parallel modules: a dominant "vector-propagation" class (approximately 50% of units) with similar visual and motor tuning but negligible position sensitivity and three classes with specific spatial relations between position, visual, and motor tuning. Surprisingly, the vector-propagation units, and only these, formed a highly precise and consistent orthogonal coordinate system aligned with Listing's plane. Selective "lesions" confirmed that the vector-propagation module provided the main drive for saccade magnitude and direction, whereas a balance between activity in the other modules was required for the correct eye-position modulation. Thus, contrary to popular expectation, error-driven learning in itself was sufficient to produce a "neural" algorithm with discrete functional modules and explicit coordinate systems, much like those observed in the real saccade generator.

Stem cell factor: biology and relevance to clinical practice

The type III tyrosine kinase receptor c-KIT and its ligand stem cell factor (SCF; also known as KIT ligand, mast cell growth factor and steel factor) are closely involved in the regulation of a wide range of tissues at different stages of life. This review provides an outline of the discovery, structure and expression of SCF and c-KIT but concentrates on their respective roles in the regulation of human haemopoiesis and how this knowledge might be exploited in the clinical setting.

Plasmin-mediated fibroblast growth factor-2 mobilisation supports smooth muscle cell proliferation in human saphenous vein

The focus of this study was identification of the contribution of the plasminogen activator-plasmin system to smooth muscle cell proliferation and migration in human saphenous vein. Segments of human saphenous vein were grown in organ culture for up to 14 days. Smooth muscle cell proliferation and migration were measured by incubating vein segments in bromodeoxyuridine, and smooth muscle cell death was detected by in situ end-labelling. Tissue-type (tPA) and urokinase-type (uPA) plasminogen activator enzymic activities were detectable in cultured saphenous vein segments, and were concentrated in focal zones. Inhibition of plasmin activity with alpha-N-acetyl-L-lysine methyl ester (NALME) or of uPA activity with a neutralising antibody caused significant decreases in smooth muscle cell proliferation in the media and the intima, but no significant changes in smooth muscle cell migration. Intimal thickness was also significantly decreased. Incubation with plasminogen or plasmin caused fibroblast growth factor-2 (FGF2) to be released into the medium. Addition of FGF2 to segments cultured with NALME reversed the inhibition of smooth muscle cell proliferation, and blocking the activity of FGF2 with a neutralising antibody caused a significant decrease in medial smooth muscle cell proliferation. These data suggest that plasmin mobilises FGF2 bound to the extracellular matrix of human saphenous vein, so that it can support smooth muscle cell proliferation and intimal thickening.

Neuroprotective adaptations in hibernation: therapeutic implications for ischemia-reperfusion, traumatic brain injury and neurodegenerative diseases

Brains of hibernating mammals are protected against a variety of insults that are detrimental to humans and other nonhibernating species. Such protection is associated with a number of physiological adaptations including hypothermia, increased antioxidant defense, metabolic arrest, leukocytopenia, immunosuppression, and hypocoagulation. It is intriguing that similar manipulations provide considerable protection as experimental treatments for central nervous system injury. This review focuses on neuroprotective mechanisms employed during hibernation that may offer novel approaches in the treatment of stroke, traumatic brain injury, and neurodegenerative diseases in humans.

Oxidative damage is the earliest event in Alzheimer disease

Recently, we demonstrated a significant increase of an oxidized nucleoside derived from RNA, 8-hydroxyguanosine (8OHG), and an oxidized amino acid, nitrotyrosine in vulnerable neurons of patients with Alzheimer disease (AD). To determine whether oxidative damage is an early- or end-stage event in the process of neurodegeneration in AD, we investigated the relationship between neuronal 8OHG and nitrotyrosine and histological and clinical variables, i.e. amyloid-beta (A beta) plaques and neurofibrillary tangles (NFT), as well as duration of dementia and apolipoprotein E (ApoE) genotype. Our findings show that oxidative damage is quantitatively greatest early in the disease and reduces with disease progression. Surprisingly, we found that increases in A beta deposition are associated with decreased oxidative damage. These relationships are more significant in ApoE epsilon4 carriers. Moreover, neurons with NFT show a 40%-56% decrease in relative 8OHG levels compared with neurons free of NFT. Our observations indicate that increased oxidative damage is an early event in AD that decreases with disease progression and lesion formation. These findings suggest that AD is associated with compensatory changes that reduce damage from reactive oxygen.

Atherosclerotic lesions are associated with increased immunoreactivity for inducible nitric oxide synthase and endothelin-1 in thoracic aortic intimal cells of hyperlipidemic Watanabe rabbits

The development and progression of atherosclerotic lesions in Watanabe heritable hyperlipidemic rabbits is associated with increases in inducible nitric oxide synthase (NOS2) and endothelin-1 (ET-1) immunoreactivity. In contrast, there is a reduction of immunoreactivity for neuronal NOS (NOS1) in aortic endothelial cells, but no change in endothelial NOS (NOS3) immunoreactivity. However, subendothelial macrophages and smooth muscle showed a different pattern of immunoreactivity of NADPH-diaphorase (NADPH-d), NOS2, ET-1, and NOS1. The lipid-rich macrophages in the intima were positively labeled for NADPH-d, NOS1, NOS2, NOS3, and ET-1. Smooth muscle cells in the subendothelium and the medial layers of the vascular wall were also positive for these markers. These results are consistent with the reduction of endothelium-dependent vasorelaxation that is known to occur during the development and progression of atherosclerosis in familial hypercholesterolemia. The data suggest a key role for vasoactive substances in the development of atherosclerosis.

Age-related differences in sensitivity to the antinociceptive effects of opioids in male rats. Influence of nociceptive intensity and intrinsic efficacy at the mu receptor

RATIONALE

Despite the widespread popularity of opioid analgesics, significant differences in the potency and effectiveness of these drugs are often observed across age groups.

OBJECTIVES

The purpose of this investigation was to examine age-related differences in sensitivity to the antinociceptive effects of mu opioids and to identify the conditions under which these differences are most apparent.

METHODS

In a warm-water tail-withdrawal procedure, young (3 months) and aged (24 months) male rats were habituated to restraint and the latencies to remove their tails from 50 degrees C (low nociceptive intensity) and 55 degrees C (high nociceptive intensity) water were measured. Opioids possessing a range of intrinsic efficacy at the mu receptor (morphine, levorphanol, buprenorphine, butorphanol, nalbuphine, nalorphine) were examined.

RESULTS

Young and aged rats were equally sensitive to the antinociceptive effects of morphine, levorphanol, and buprenorphine when tested at the low nociceptive intensity. When these drugs were tested at the high nociceptive intensity, differences between the two age groups became apparent, such that aged rats were significantly more sensitive to the antinociceptive effects of these drugs than young rats. Differences between age groups were most apparent when butorphanol, nalbuphine, and nalorphine were tested, in that each of these drugs produced maximal levels of antinociception in aged rats under conditions in which they failed to produce antinociceptive activity in young rats. Under conditions in which lower efficacy opioids failed to produce antinociceptive activity in young rats, they antagonized the effects of morphine in drug combination tests.

CONCLUSIONS

These data may be taken as evidence that aged male rats are more sensitive to the antinociceptive effects of mu opioids than young male rats, and that age-related differences in opioid sensitivity are most apparent when lower efficacy opioids and higher nociceptive intensities are employed during behavioral testing.

C-kit mutation screening in patients with acute myeloid leukaemia: adaptation of a Giemsa-stained bone-marrow smear DNA extraction technique

The scarcity of viable tissue samples for leukaemia research is widely recognised and currently restrictive. Archival bone-marrow smears present a valuable resource that can be exploited easily for mutational analysis. Here, a modified technique to extract DNA is described, and used subsequently for mutation/polymorphism screening of the stem-cell factor receptor proto-oncogene c-kit in 23 patients with acute myeloid leukaemia (AML). The selected method was straightforward and used bone-marrow material scraped from periodic acid-Schiff, sudan black B and May-Grünwald/Giemsa-stained preparations, and treated initially with proteinase K prepared in digestion buffer to digest all proteinaceous matter. Following incubation, saturated sodium chloride was added and DNA extracted from the supernatant by phenol/chloroform/isoamyl alcohol treatment. Retrieved DNA was precipitated with ethanol at -20 degrees C overnight, washed with 95% ethanol, air-dried, resuspended using purite water and stored at -20 degrees C prior to use in mutational analysis. The extraction method described was compared with a commercial reagent for combined DNA, RNA and protein isolation using cryopreserved cells from 20 patients with AML. The quality of extracted DNA isolated by the two methods was comparable by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) techniques. Bone-marrow biopsies are performed regularly on each AML patient to monitor the disease; therefore, an extraction method using this resource could liberate a valuable source of DNA for study (e.g. molecular investigations, including mutation/polymorphism screening etc.). This would allow fresh and programme-frozen cells to be reserved for those investigations requiring intact, viable cells. The use of archived bone-marrow smears would permit vast increase in the scope for retrospective testing and large-scale analyses.

Active glycation in neurofibrillary pathology of Alzheimer disease: N(epsilon)-(carboxymethyl) lysine and hexitol-lysine

Advanced glycation end products are a diverse class of posttranslational modifications, stemming from reactive aldehyde reactions, that have been implicated in the pathogenesis of a number of degenerative diseases. Because advanced glycation end products are accelerated by, and result in formation of, oxygen-derived free radicals, they represent an important component of the oxidative stress hypothesis of Alzheimer disease (AD). In this study, we used in situ techniques to assess N(epsilon)-(Carboxymethyl)lysine (CML), the predominant advanced glycation end product that accumulates in vivo, along with its glycation-specific precursor hexitol-lysine, in patients with AD as well as in young and aged-matched control cases. Both CML and hexitol-lysine were increased in neurons, especially those containing intracellular neurofibrillary pathology in cases of AD. The increase in hexitol-lysine and CML in AD suggests that glycation is an early event in disease pathogenesis. In addition, because CML can result from either lipid peroxidation or advanced glycation, while hexitol-lysine is solely a product of glycation, this study, together with studies demonstrating the presence of 4-hydroxy-2-nonenal adducts and pentosidine, provides evidence of two distinct oxidative processes acting in concert in AD neuropathology. Our findings support the notion that aldehyde-mediated modifications, together with oxyradical-mediated modifications, are critical pathogenic factors in AD.

Induction of NADPH cytochrome P450 reductase by the Alzheimer beta-protein. Amyloid as a "foreign body"

A large body of data suggests that the Alzheimer's amyloid peptide (Abeta) causes degeneration and death of neurons by mechanisms that involve reactive oxygen species. The pathways involved in Abeta-mediated oxidative injury are only partially understood. We theorized that abnormal microaggregates and/or pathological conformations of Abeta peptides may behave as xenobiotics and trigger the induction of NADPH cytochrome P450 reductase (CP450r), an enzyme which, if induced by non-physiological substrates (such as xenobiotics like drugs or other 'foreign molecules'), is known to cause oxidative stress. In order to test this hypothesis, i.e. that Abeta can increase the expression of CP450r, SK-N-SH human neuroblastoma cells were exposed to Abeta25-35 and Abeta1-42 and then examined for induction of this enzyme in immunoblots, using specific antibodies. Following exposure to Abeta peptides, neuroblastoma cells showed a clear-cut induction of CP450r. To determine whether this mechanism is operational in vivo, we investigated the expression of CP450r in a transgenic mouse model of Alzheimer's disease (AD) and in brains from patients afflicted with AD, using an immunocytochemical approach. Tissue sections from brains of transgenic mice exhibited strong immunoreactivity for CP450r, surrounding amyloid deposits. The pattern of expression of CP450r was similar to that exhibited by neuritic and oxidative stress markers. Sections from non-transgenic mice showed no detectable immunoreactivity. Immunostaining of sections from four brains with neuropathologically confirmed AD showed a pattern of abnormality different from transgenic mice that was characterized by abnormal immunoreactivity for CP450r within the cytoplasm of cortical neurons. No labeling was seen in sections from aged-matched control brains. The data showed that CP450r is induced by Alzheimer amyloid peptide and that such a response must be considered as one possible mechanism whereby Abeta causes oxidative stress.

New ages for the last Australian megafauna: continent-wide extinction about 46,000 years ago

All Australian land mammals, reptiles, and birds weighing more than 100 kilograms, and six of the seven genera with a body mass of 45 to 100 kilograms, perished in the late Quaternary. The timing and causes of these extinctions remain uncertain. We report burial ages for megafauna from 28 sites and infer extinction across the continent around 46,400 years ago (95% confidence interval, 51,200 to 39,800 years ago). Our results rule out extreme aridity at the Last Glacial Maximum as the cause of extinction, but not other climatic impacts; a "blitzkrieg" model of human-induced extinction; or an extended period of anthropogenic ecosystem disruption.

Chemistry and Biochemistry of Oxidative Stress in Neurodegenerative Disease

The age-related neurodegenerative diseases exemplified by Alzheimer&hyp;s disease (AD), Lewy body diseases such as Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington&hyp;s disease are characterized by the deposition of abnormal forms of specific proteins in the brain. Although several factors appear to underlie the pathological depositions, the cause of neuronal death in each disease appears to be multifactorial. In this regard, evidence in each case for a role of oxidative stress is provided by the finding that the pathological deposits are immunoreactive to antibodies recognizing protein side-chains modified either directly by reactive oxygen or nitrogen species, or by products of lipid peroxidation or glycoxidation. Although the source(s) of increased oxidative damage are not entirely clear, the findings of increased localization of redox-active transition metals in the brain regions most affected is consistent with their contribution to oxidative stress. It is tempting to speculate that free radical oxygen chemistry plays a pathogenetic role in all these neurodegenerative conditions, though it is as yet undetermined what types of oxidative damage occur early in pathogenesis, and what types are secondary manifestations of dying neurons. Delineation of the profile of oxidative damage in each disease will provide clues to how the specific neuronal populations are differentially affected by the individual disease conditions.

Hibernation, a model of neuroprotection

Hibernation, a natural model of tolerance to cerebral ischemia, represents a state of pronounced fluctuation in cerebral blood flow where no brain damage occurs. Numerous neuroprotective aspects may contribute in concert to such tolerance. The purpose of this study was to determine whether hibernating brain tissue is tolerant to penetrating brain injury modeled by insertion of microdialysis probes. Guide cannulae were surgically implanted in striatum of Arctic ground squirrels before any of the animals began to hibernate. Microdialysis probes were then inserted in some animals after they entered hibernation and in others while they remained euthermic. The brain tissue from hibernating and euthermic animals was examined 3 days after implantation of microdialysis probes. Tissue response, indicated by examination of hematoxylin and eosin-stained tissue sections and immunocytochemical identification of activated microglia, astrocytes, and hemeoxygenase-1 immunoreactivity, was dramatically attenuated around probe tracks in hibernating animals compared to euthermic controls. No difference in tissue response around guide cannulae was observed between groups. Further study of the mechanisms underlying neuroprotective aspects of hibernation may lead to novel therapeutic strategies for stroke and traumatic brain injury.

Barriers to acute stroke therapy and stroke prevention in Mexican Americans

BACKGROUND AND PURPOSE

The purpose of this study was to identify specific targets to improve acute stroke treatment and stroke prevention in the Mexican American (MA) community.

METHODS

A professional, academic survey research team provided structured questions and elicited responses from 719 subjects identified by random-digit dialing in the biethnic community of Corpus Christi, TEXAS: This community of approximately 300 000 is approximately half MA and half non-Hispanic white (NHW). The cooperation rate for the survey was 58%.

RESULTS

MAs (n=357) were younger, less well educated, and had lower family income than NHWs (n=362, P=0.001). MAs had a higher prevalence of diabetes mellitus (P=0.001) but similar rates of hypertension, elevated cholesterol, and current tobacco use. MAs less commonly recognized that acute stroke therapy existed (P=0.029), were less likely to acknowledge a time window for acute stroke treatment (P=0.001), and were more reticent to say they would call 911 for stroke symptoms (P=0.01) than NHWS: MAs were significantly less able to recall stroke symptoms and risk factors than NHWS: Only approximately 20% of both groups identified stroke as the NO: 1 cause of disability. MAs expressed less confidence in their ability to prevent stroke (P<0.001), more distrust in the medical establishment (P=0.007), and more concern that money impedes their seeking medical care (P<0.001).

CONCLUSIONS

There are significant barriers to both acute stroke treatment and stroke prevention in MAS: This study identifies specific targets amenable for testing in an intervention project following confirmation by a methodology other than telephone survey.

Pharmacologic characterization of BMS-191095, a mitochondrial K(ATP) opener with no peripheral vasodilator or cardiac action potential shortening activity

Previous work described ATP-sensitive K(+) channel (K(ATP)) openers (e.g., BMS-180448), which retain the cardioprotective activity of agents such as cromakalim while being significantly less potent as vasodilators. In this study, we describe the pharmacologic profile of BMS-191095, which is devoid of peripheral vasodilating activity while retaining glyburide-reversible cardioprotective activity. In isolated rat hearts subjected to 25 min of global ischemia and 30 min of reperfusion, BMS-191095 increased the time to onset of ischemic contracture with an EC(25) of 1.5 microM, which is comparable to 4.7 microM and 3.0 microM for cromakalim and BMS-180448, respectively. Comparisons of cardioprotective and vasorelaxant potencies in vitro and in vivo showed BMS-191095 to be significantly more selective for cardioprotection with virtually no effect on peripheral smooth muscle, whereas cromakalim showed little selectivity. In addition to increasing the time to the onset of contracture, BMS-191095 improved postischemic recovery of function and reduced lactate dehydrogenase release in the isolated rat hearts. The cardioprotective effects of BMS-191095 were abolished by glyburide and sodium 5-hydroxydecanoate (5-HD). BMS-191095 did not shorten action potential duration in normal or hypoxic myocardium within its cardioprotective concentration range nor did it activate sarcolemmal K(ATP) current (< or =30 microM). BMS-191095 opened cardiac mitochondrial K(ATP) with a K(1/2) of 83 nM, and this was abolished by glyburide and 5-HD. These results show that the cardioprotective effects of BMS-191095 are dissociated from peripheral vasodilator and cardiac sarcolemmal K(ATP) activation. Agents like BMS-191095 may owe their cardioprotective selectivity to selective mitochondrial K(ATP) activation.

Mechanisms by which metals promote events connected to neurodegenerative diseases

Although the exact causative phenomenon responsible for the onset and progression of neurodegenerative disorders is at present unresolved, there are some clues as to the mechanisms underlying these chronic diseases. This review addresses mechanisms by which endogenous or environmental factors, through interaction with redox active metals, may initiate a common cascade of events terminating in neurodegeneration.

Melatonin acts as antioxidant and pro-oxidant in an organotypic slice culture model of Alzheimer's disease

An organotypic mouse brain slice culture system of Alzheimer's disease (AD) under low oxygen partial pressures was developed to determine the antioxidant properties of the pineal hormone melatonin in vitro. Assays for biochemical markers of oxidative stress including redox active iron assay, heme-oxygenase-1 and 8-hydroxyguanosine inmunoreactivity were performed along with morphological analysis for stressed tissue following amyloid-beta (A beta) 1-40 insult. Melatonin (100 microM) significantly reduced the appearance of condensed chromatin, redox active iron, heme-oxygenase-1 induction and 8-hydroxyguanosine immunoreactivity caused by 50 microM A beta. Melatonin also prevented A beta-induced morphological signs of oxidative stress in tissue ultrastructure, including edema and dark degenerating profiles as visualized under electron microscope. At elevated concentrations (1 mM), melatonin induced redox active iron and heme-oxgenase-1 immunoreactivity. Thus, while melatonin may be a potential therapeutic agent in the prevention of oxidative stress associated with A beta and AD, it can also induce markers of oxidative stress at millimolar concentrations.

Measuring the direct costs of graduate medical education training in Minnesota

PURPOSE

To demonstrate the usefulness of self-reported cost-accounting data from the sponsors of training programs for estimating the direct costs of graduate medical education (GME). The study also assesses the relative contributions of resident, faculty, and administrative costs to primary care, surgery, and the combined programs of radiology, emergency medicine, anesthesiology, and pathology (REAP).

METHOD

The data were the FY97 direct costs of clinical education reported to Minnesota's Department of Health by eight sponsors of 117 accredited medical education programs, representing 394 sites of training (both hospital- and community-based) and 2,084 full-time-equivalent trainees (both residents and fellows). Average costs of clinical training were calculated as residency, faculty, and administrative costs. Preliminary analysis showed average costs by type of training programs, comparing the cost components for surgery, primary care, and REAP.

RESULTS

The average direct cost of clinical training in FY97 was $130,843. Faculty costs were 52%, resident costs were 26%, and administrative costs were 20% of the total. Primary care programs' average costs were lower than were those of either surgery or REAP programs, but proportionally they included more administrative costs.

CONCLUSIONS

As policymakers assess government subsidies for GME, more detailed cost information will be required. Self-reported data are more cost-effective and efficient than are the more detailed and costly time-and-motion studies. This data-collection study also revealed that faculty costs, driven by faculty hours and base salaries, represent a higher proportion of direct costs of GME than studies have shown in the past.

The use of granulocyte colony-stimulating factor for treatment of autoimmune neutropenia

The advent of better diagnostic tools, molecular techniques, and cytokine therapies have come together at the end of the 20th century to provide an improved outlook for patients with autoimmune neutropenia. Severe chronic neutropenia is no longer idiopathic in most cases, and growth factor therapy can be safely offered to selected patient groups. Previously unsuccessful and even dangerous forms of treatment are no longer appropriate, and G-CSF treatment appears to be safe when administered long term. Fears about transformation of these disorders into acute myeloblastic leukemia probably relate to the underlying natural history of these disorders rather than to their treatment.

Mitochondrial abnormalities in Alzheimer's disease

The finding that oxidative damage, including that to nucleic acids, in Alzheimer's disease is primarily limited to the cytoplasm of susceptible neuronal populations suggests that mitochondrial abnormalities might be part of the spectrum of chronic oxidative stress of Alzheimer's disease. In this study, we used in situ hybridization to mitochondrial DNA (mtDNA), immunocytochemistry of cytochrome oxidase, and morphometry of electron micrographs of biopsy specimens to determine whether there are mitochondrial abnormalities in Alzheimer's disease and their relationship to oxidative damage marked by 8-hydroxyguanosine and nitrotyrosine. We found that the same neurons showing increased oxidative damage in Alzheimer's disease have a striking and significant increase in mtDNA and cytochrome oxidase. Surprisingly, much of the mtDNA and cytochrome oxidase is found in the neuronal cytoplasm and in the case of mtDNA, the vacuoles associated with lipofuscin. Morphometric analysis showed that mitochondria are significantly reduced in Alzheimer's disease. The relationship shown here between the site and extent of mitochondrial abnormalities and oxidative damage suggests an intimate and early association between these features in Alzheimer's disease.

To help or hinder: Which is more important in explaining a physician's willingness to recommend a health plan?

PURPOSE

To examine how specific health plan practices contribute to physicians' willingness to recommend a health plan to a patient, and whether the relative importance of plan practices is viewed differently when patients are seriously ill.

METHODS

The Physician's Evaluation of Health Plans Project has surveyed 1,757 generalist physicians in 16 health plans in 5 areas nationwide. Each physician reported on one plan. Three multi-item scales assessed physicians' perceptions of health plan activities that facilitated or impeded high-quality care in the plans and the clinical capabilities of plan physicians. Regression analyses were used to explore relations between facilitators, barriers, and clinical capabilities, and two global physician judgments (the physician's willingness to recommend a plan and their judgment that a plan provided lower quality for sicker patients).

RESULTS

A physician's willingness to recommend a health plan is more highly related to what plans do to facilitate care than to the barriers created by plans in managing care. However, barriers to care were substantially more important when evaluating health plan quality for sicker patients.

CONCLUSIONS

From the physician's perspective, the relative importance of plan strategies to manage care is different for typical patients and patients who are more seriously ill. Efforts to collect information on health plan quality should separately evaluate care for sicker patients, in addition to evaluating the overall performance of the health plan.

Attenuation of fear conditioning by antisense inhibition of brain corticotropin releasing factor-2 receptor

Corticotropin releasing factor (CRF) is an important regulator of the endocrine, behavioral, autonomic and immune responses to stress. Two high affinity CRF receptors have been identified, which are distributed in distinct anatomical regions. CRF(1) receptors have been relatively well characterized and antagonists to this receptor effectively block stress-induced behaviors in rodents. The function of CRF(2) receptors, which are highly expressed in limbic brain regions, is less well understood. Therefore, an antisense oligonucleotide approach was used to study the role of CRF(2) receptors in the lateral septum in rats. An antisense oligonucleotide directed against the CRF(2) receptor mRNA reduced expression of CRF(2) receptors by 60--80%. In shock-induced freezing tests, animals administered the antisense oligonucleotide exhibited a significant reduction in freezing duration. However, pain sensitivity and locomotor activity were unaltered. A four-base mismatch of the antisense sequence had no significant effects on CRF(2) receptor density and on freezing behavior. These data support the involvement of CRF(2) receptors in fear conditioning. CRF(1) receptor antagonists also reduce freezing in this test. Additional studies to determine the effects of simultaneous inhibition of both receptor subtypes show that rats receiving both CRF(2) receptor antisense oligonucleotide and CRF(1) receptor antagonist froze significantly less than animals treated with either agent alone. These results provide additional evidence for the role of CRF(2) receptors in mediating the stress-induced actions of endogenous CRF.

Sensitivity to the effects of sedative-hypnotics on motor performance: influence of task difficulty and chronic phenobarbital administration

The present investigation examined sensitivity to the effects of various sedative-hypnotics on motor performance in rats treated chronically with phenobarbital. Eight rats were trained to walk on a rotorod treadmill at low (8 r.p.m.) and high (24 r.p.m.) rotational speeds. Prior to the chronic regimen, phenobarbital, pentobarbital, amobarbital, diazepam and clonazepam produced dose-dependent impairments in motor performance at both speeds. During chronic treatment with phenobarbital (100 mg/kg/day), tolerance was conferred to the effects of all the drugs examined, as evidenced by rightward shifts in their dose-effect curves. For all drugs, the magnitude of this tolerance was generally consistent across the two speeds. Following a 6-week washout period, during which no drugs were administered, dose-effect curves for each drug shifted back toward their original (i.e. pre-chronic) positions. Under all conditions, the doses required for each drug to impair motor performance at the low speed were higher than those required to impair motor performance at the high speed. These data suggest that sensitivity to the motor-impairing effects of sedative-hypnotics is influenced by the difficulty of the behavioral task, but that task difficulty does not modulate the maximal extent to which tolerance and cross-tolerance are expressed.

Induction of HO-1 and NOS in doppel-expressing mice devoid of PrP: implications for doppel function

Ectopic expression of the doppel (Dpl) protein, a homologue of the prion protein (PrP), was recently associated with cerebellar Purkinje cell degeneration observed in two aging prion protein knock-out (Prnp(0/0)) mouse lines. We investigated the possible role of Dpl in oxidative metabolism. Two Prnp(0/0) mouse lines of similar genetic background were studied. One line expresses Dpl in the brain and displays Dpl-associated cerebellar abnormalities. The other has no elevated expression of Dpl and no cerebellar abnormalities. We observed a correlation between Dpl expression and the induction of both heme oxygenase 1 (HO-1) and nitric oxide synthase systems (nNOS and iNOS). These responses are suggestive of increased oxidative stress in the brains of the Dpl-expressing Prnp(0/0) mice. No induction was observed with Hsp-60, indicating a specific response by the HO/NOS system. We proposed that Dpl expression exacerbates oxidative damage that is antagonistic to the protective function of wild-type PrP.

Abortive apoptosis in Alzheimer's disease

Multiple studies suggest that neuronal death in Alzheimer's disease (AD) is the result of an apoptotic mechanism. However, the stereotypical manifestations that define the terminal phases of apoptosis, such as chromatin condensation, apoptotic bodies, and blebbing, are not seen in AD. In this study, we show that the caspases, such as caspase 6, which cleave amyloid-beta protein precursor (A beta PP) and presenilins, are localized to the pathological lesions associated with AD. However, while upstream caspases such as 8 and 9 are clearly found in association with the intraneuronal pathology in AD, downstream caspases such as 3, 6 and 7 are present only at control levels. Given that execution of apoptosis requires amplification of the caspase-mediated apoptotic signal, our results indicate that in AD there is a lack of effective apoptotic signal propagation to downstream caspase effectors. Therefore, while the presence of caspases, especially caspase 6, in association with extracellular deposits of amyloid-beta, could obviously have important ramifications on the proteolytic processing of A beta PP and, thereby, on disease pathogenesis, it seems that AD represents the first in vivo situation reported in which the initiation of apoptosis does not proceed to caspase-dependent cell death. This novel phenomenon of apoptotic avoidance, which we term abortive apoptosis, or abortosis, may represent an exit from the caspase-induced apoptotic program that leads to neuronal survival in AD.

ACTIVATION OF HUMAN AIRWAY EPITHELIAL CELLS BY NON-HLA ANTIBODIES DEVELOPED AFTER LUNG TRANSPLANTATION: A POTENTIAL ETIOLOGICAL FACTOR FOR BRONCHIOLITIS OBLITERANS SYNDROME1

BACKGROUND

The main cause of morbidity and mortality after lung transplantation (LT) is bronchiolitis obliterans syndrome (BOS). Anti-HLA antibodies development after LT has been shown to play an important role in BOS pathogenesis. However, the nature of non-HLA antibodies developed after LT and their role in BOS pathogenesis have not been determined.

METHODS

Sera from 16 BOS+ patients and 11 BOS- patients were collected at 12, 24, 36, and 48 months after LT. Anti-HLA class I and class II antibodies were absorbed with pooled human platelets and pooled human lymphoblastoid cell lines, respectively. Then, the presence of non-HLA antibodies against several cell lines from different origin was determined by flow cytometric analysis. Antibody-positive samples were tested for induction of proliferation and growth factor production in two selected airway epithelial cell (AEC) lines.

RESULTS

Five of 16 BOS+ patients (31.2%) and 0 of 11 BOS- patients (0%) developed anti-AEC antibodies after LT (P=0.05). No reactivity against endothelial cells, lymphocytes, monocytes, or granulocytes was detected. Further analysis of two selected sera demonstrated the development of reactivity against a 60-kDa antigen expressed by 60% of AEC lines and only 12% of cell lines from other tissues. Antibody binding to this antigen induced intracellular Ca++ influx, tyrosine phosphorylation, proliferation, and up-regulation of transforming growth factor-beta and heparin-binding epidermal growth factor mRNA transcription in AECs.

CONCLUSIONS

These results indicate that anti-AEC antibodies may play a role in the immunopathogenesis of BOS in the absence of anti-HLA antibodies.

Stress-induced alterations in locus coeruleus gene expression during ontogeny

Brainstem noradrenergic neurons, particularly the locus-coeruleus (LC), play a pivotal role in modulating the central stress response and have been implicated in regulating the hypothalamic-pituitary-adrenal (HPA) axis. In adult rats, acute stress causes an increase in LC firing and tyrosine hydroxylase (TH) gene expression. While the role of the LC-norepinephrine (LC-NE) system in the adult stress response has been well characterized, there is limited evidence for its participation during development. Previous studies described the neonatal HPA axis as hyporeactive because of stimulus-selective pituitary activation. However, maternal deprivation does reinstate stress-induced endocrine activity and can amplify the neural stress response. Considering that LC neurons can modulate neuroendocrine activity, we hypothesized that the LC-NE system would be stress-responsive during development. Because maternal deprivation (DEP) can alter the central stress response, we examined the LC-NE stress response in both DEP and non-deprived (NDEP) pups. Following an isotonic saline injection (stressor) the time course of TH, c-fos and glucocorticoid receptor (GR) mRNA was examined. Stress-induced TH mRNA was increased in DEP pups at postnatal day (pnd) 12 and in both NDEP and DEP pups at pnd 18. At 15, 30 and 240 min c-fos mRNA was markedly increased in all groups examined. GR mRNA was not altered at pnd 12; however, at pnd 18 NDEP pups showed reduced GR mRNA expression. These data indicate that during ontogeny the LC-NE system is stress-responsive to an acute mild challenge. Activation of LC-NE neurons suggests that this system may participate in modulating the neuroendocrine stress response during development.

Erythrocyte, plasma, and serum antioxidant activities in untreated toxic multinodular goiter patients

Erythrocyte, plasma, and serum antioxidant activities were studied in patients with newly diagnosed and untreated toxic multinodular hyperthyroid goiter and compared to healthy control subjects. Erythrocyte antioxidant enzyme activities, glutathione, malondialdehyde, and ceruloplasmin levels were significantly increased, whereas serum vitamin E, plasma vitamin C, and selenium levels were decreased in hyperthyroid patients compared to control subjects. The findings show that untreated toxic multinodular goiter causes profound alterations in components of the antioxidant system in erythrocytes indicative of increased oxidative stress. Taken together, these data suggest that hyperthyroid patients may benefit from dietary supplements of antioxidants.

Melatonin reduces interleukin secretion in amyloid-beta stressed mouse brain slices

Neurodegeneration in Alzheimer's disease (AD) is associated with many features of the immune system. For example, cytokines such as IL-6, synthesized by microglia and astrocytes, are associated with senile plaques. To further study the role of cytokines in early stage AD neurodegeneration, an organotypic mouse brain slice culture system with microglia and astrocytes was developed. Amyloid-beta(Abeta1-40) induced the secretion of both IL-1beta and IL-6. Melatonin, an antioxidant and pineal hormone, reduced interleukin secretion in a concentration dependent manner. We also observed that melatonin, alone, had no effect on IL-1beta secretion but at a concentration of 500 microM induced the secretion of IL-6. This organotypic slice system can be used to study the early role of immune system molecules on neurodegeneration.

Measuring the physician perspective on quality of care in health plans

Physicians provide one source of information about the quality of care in health plans, but concerns exist that physicians cannot distinguish quality from financial considerations or other underlying attitudes. We examined whether physicians can (a) distinguish different domains of health plan quality and (b) distinguish health plan quality from their underlying attitudes. We analyzed data on 419 generalist physicians from four health plans. Three scales assessed physicians' perceptions of facilitators and barriers to high-quality care in the plans and the clinical capabilities of plan physicians. Structural equation modeling indicated that physicians could distinguish domains of health plan quality. Physicians could also distinguish plan quality from their attitudes toward the plan, but plan quality was more highly correlated with general managed care attitudes than expected. These data suggest that physicians can provide information about health plan quality, but it will be important to validate these measures against patient outcomes.

Arson. Tracking the culprit in Alzheimer's disease

By focusing on the lesions in Alzheimer's disease, and regarding them as either critical or irrelevant, researchers may have missed much regarding the origin and pathogenesis of this disease. In this article we consider that the lesions are so obvious not only because they are pathognomonic for Alzheimer's disease, but also because they represent a major departure from normal physiology. We suggest that these myriad pathological changes are homeostatic compensatory mechanisms to aging.

Intravascular ultrasound-guided interventions in coronary artery disease: a systematic literature review, with decision-analytic modelling, of outcomes and cost-effectiveness

BACKGROUND

Intravascular ultrasound (IVUS) is the generic name for any ultrasound technology used in vivo within the blood vessels. More specifically, intracoronary ultrasound enables imaging of the coronary arteries from within the lumen. This review concentrates on the role of intracoronary ultrasound as an adjunct to interventional cardiology.

OBJECTIVES

(1) To identify the literature on IVUS for guiding coronary interventions, and to synthesise evidence about outcomes compared with outcomes when IVUS guidance has not been used. (2) To use this evidence, together with other information about costs and outcomes, to model the cost effectiveness of IVUS guidance. (3) To synthesise the evidence on the reproducibility of measurements of cross-sectional area made using IVUS.

METHODS

DATA SOURCES

(1) Electronic searches of MEDLINE, EMBASE, Science Citation Index, Index to Scientific and Technical Proceedings, Engineering Compendex, Engineering Page One, Cochrane Library, Inside (British Library), 1990-98. (2) Contacting experts and centres of expertise, 1990-99. (3) Internet search, 1990-99.

METHODS

STUDY SELECTION

Studies of IVUS-guided coronary interventions performed on humans were included in the review. Non-English language studies were also included when they covered IVUS-guided stenting or angioplasty. Control evidence regarding outcomes without IVUS guidance was sought only from randomised controlled trials (RCTs). Studies investigating the reproducibility of measurements of cross-sectional area were included only if the results were expressed in terms of the mean and standard deviation of paired differences.

METHODS

DATA EXTRACTION

Checklists that covered study details, patient characteristics and results were completed independently by three reviewers. Consensus was reached on any disagreements. Local data were gathered on the costs of IVUS-guided stenting.

METHODS

DATA SYNTHESIS

Overall event rates were calculated by pooling patient results from the included studies. A decision-analytic model was used to combine information from the literature with cost estimates, in order to predict cost-effectiveness in terms of cost per restenosis event avoided by the use of IVUS guidance. The analysis was performed from the perspective of the healthcare provider. Sensitivity analysis was undertaken. A simple extrapolation was made to long-term outcome so that cost-utility (using quality-adjusted life years (QALYs)) could be estimated. The minimum detectable change in cross-sectional area was estimated from the reproducibility results.

RESULTS

Only one study on IVUS-guided angioplasty satisfied the inclusion criteria, and there were no studies on IVUS-guided atherectomy or other IVUS-guided interventions that satisfied the inclusion criteria. Of the 15 articles on IVUS-guided stenting that satisfied the inclusion criteria, seven presented data on outcomes at 6 months post-intervention. The angiographic restenosis rate was 16 +/- 1%. This compared with 24 +/- 2% derived from five articles on stenting without IVUS guidance. Data for follow-up periods longer than 6 months were presented in only two studies. Data from a total of five studies were included in the decision-analytic model. The cost per restenosis event avoided was 1545 pound sterling. After extrapolation to long-term outcome, the calculated cost per QALY was 6438 pound sterling. The baseline QALY gain was only 0.03 years. Sensitivity analysis resulted in large differences between the best- and worst-case scenarios, for example, from a saving of 5000 pound sterling to a cost of 24,000 pound sterling restenosis event avoided. The smallest changes in cross-sectional area that could be measured were 1.6 mm2 by a single observer and 1.9 mm2 by different observers.

CONCLUSIONS

Implications for healthcare: The evidence available is too weak for there to be any reliable implications for clinical practice. (ABSTRACT TRUNCATED)

Redox-active iron mediates amyloid-beta toxicity

While amyloid-beta toxicity is mediated by oxidative stress and can be attenuated by antioxidants, the actual biochemical mechanism underlying neurotoxicity remains to be established. However, since aggregated amyloid-beta can interact with transition metals, such as iron, both in vitro and in vivo, we suspected that bound iron might be the mediator of toxicity such that holo- and apo-amyloid would have differential effects on cellular viability. Here we demonstrate that when amyloid-beta is pretreated with the iron chelator deferoxamine, neuronal toxicity is significantly attenuated while conversely, incubation of holo-amyloid-beta with excess free iron restores toxicity to original levels. These data, taken together with the known sequelae of amyloid-beta, suggest that the toxicity of amyloid-beta is mediated, at least in part, via redox-active iron that precipitates lipid peroxidation and cellular oxidative stress.

The Internet and clinical psychology: a general review of the implications

The Internet has grown exponentially from its original conception and now takes the form of a vast network of interconnected computers. It encompasses such a wide arena within science that its impact cannot be ignored. This article reviews some of the areas where the Internet is relevant to Clinical Psychology. Three main areas identified and expanded upon are (i) use of the Internet as a communication medium within this domain, (ii) teaching of the discipline, and (iii) use of the Internet as a tool for psychological research. Within these three areas, examples of the applicability of the Internet are discussed as well as its limitations. In summary, use of the Internet within the psychological domain has many advantages and as such should be embraced by the clinical psychologist.

Broadband proton decoupling for in vivo brain spectroscopy in humans

A new decoupling sequence, PBAR, is described for broadband heteronuclear decoupling in vivo in humans at 1.5T. The sequence uses non-adiabatic, frequency- and amplitude-modulated inversion pulses designed to minimize decoupling sidebands at low applied gammaB(2) RF field levels and to cover only the narrow range of resonance offsets encountered in practice. The offset dependence of the decoupling efficiency of PBAR is demonstrated and compared to the conventional WALTZ-4 sequence. At the same average power levels, PBAR had slightly reduced bandwidth but significantly less intense decoupling sidebands. Applications of PBAR are shown in vivo in the human brain both for (31)P and natural abundance (13)C spectroscopy using volume decoupling coils. The PBAR sequence allows whole brain [(1)H]-[13]C decoupling to be performed at 1.5T with a standard head coil within FDA guidelines for RF power deposition. Magn Reson Med 45:226-232, 2001.

Proteomics

The term "proteomics" describes the technologies collectively used to define the protein complement of the genome or "proteome" (1,2). The recent growth of this discipline is reflected in the many review articles available (3-7). In addition to describing all the proteins encoded by the genome, the proteome also provides information on protein expression under defined conditions or at a particular point in time, the occurrence of posttranslational modifications, and the distribution of proteins within the cell. Proteomics, most commonly, combines the technique of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), developed simultaneously but independently by O'Farrell (8) and Klose (9) in 1975, with image analysis, protein mass spectrometry, and database searching to assign protein identities to spots from 2D gels. Recent advances in the sensitivity and accuracy of protein mass spectrometry (3,10-12), coupled with availability of the complete genome sequence of two strains of Mycobacterium tuberculosis (13, http://www.tigr.org/), have facilitated the study of the proteome of this organism. Under defined growth conditions, this may help to elucidate the mechanism of M. tuberculosis survival within the host.

Use of two-dimensional gel electrophoresis to measure changes in synovial fluid proteins from patients with rheumatoid arthritis treated with antibody to CD4

Synovial fluid proteins from microliter volumes of synovial fluid were resolved by two-dimensional polyacrylamide gel electrophoresis and detected by silver staining to investigate the feasibility of using two-dimensional (2D) electrophoresis in the clinical research setting and provide global disease information of disease progression. Several hundred proteins could be resolved as spots, many of which displayed the characteristic pattern of plasma-derived glycoproteins. The lowest level of detection was approximately 0.2 ng from a total of 50 microg of protein loaded. Most of the proteins could be identified on the basis of pI and molecular weight when compared with plasma protein maps on the World Wide Web. Unknown proteins were characterized by mass spectrometry of tryptic digests and by comparison with peptide databases. Synovial fluids from patients with rheumatoid arthritis were analyzed using this technique. Each subject received a fixed dose of antibody to CD4 as part of a phase II clinical trial to determine the efficacy of this immunosuppressive treatment in modifying disease activity. Synovial fluid was removed at day 0, followed by administration of antibody. Subsequent removal of synovial fluid and additional administration of antibody were carried out at different times thereafter. Changes in levels of acute-phase proteins were quantified by densitometry of silver-stained 2D polyacrylamide gels. Other parameters of disease progression such as serum C-reactive protein and physician's global assessment of clinical condition were used for comparison. In this way, changes in acute-phase proteins towards normal levels, as measured by 2D polyacrylamide gel electrophoresis, could be correlated with clinical improvement and conventional clinical chemistry measurements. Thus, the system can be used for quantitative analysis of protein expression in sites of autoimmune disease activity such as the synovial fluid of rheumatoid arthritis patients.

Activation and redistribution of c-jun N-terminal kinase/stress activated protein kinase in degenerating neurons in Alzheimer's disease

Cellular responses to increased oxidative stress appear to be a mechanism that contributes to the varied cytopathology of Alzheimer's disease (AD). In this regard, we suspect that c-Jun N-terminal kinase/Stress activated protein kinase (JNK/SAPK), a major cellular stress response protein induced by oxidative stress, plays an important role in Alzheimer disease in susceptible neurons facing the dilemma of proliferation or death. We found that JNK2/SAPK-alpha and JNK3/SAPK-beta were related to neurofibrillary pathology and JNK1/SAP-Kgamma related to Hirano bodies in cases of AD but were only weakly diffuse in the cytoplasm in all neurons in control cases and in non-involved neurons in diseased brain. In this regard, in hippocampal and cortical regions of individuals with severe AD, the activated phospho-JNK/SAPK was localized exclusively in association with neurofibrillar alterations including neurofibrillary tangles, senile plaque neurites, neuropil threads and granulovacuolar degeneration structures (GVD), completely overlapping with tau-positive neurofibrillary pathology, but was virtually absent in these brain regions in younger and age-matched controls without pathology. However, in control patients with some pathology, as well as in mild AD cases, there was nuclear phospho-JNK/SAPK and translocation of phospho-JNK/SAPK from nuclei to cytoplasm, respectively, indicating that the activation and re-distribution of JNK/SAPK correlates with the progress of the disease. By immunoblot analysis, phospho-JNK/SAPK is significantly increased in AD over control cases. Together, these findings suggest that JNK/SAPK dysregulation, probably resulting from oxidative stress, plays an important role in the increased phosphorylation of cytoskeletal proteins found in AD.

The existence of the vomeronasal organ in postnatal chimpanzees and evidence for its homology with that of humans

It is currently thought that New World monkeys, prosimians, and humans are the only primates to possess vomeronasal organs (VNOs) as adults. Recent studies of the human VNO suggest that previous investigations on Old World primates may have missed the VNO. We examined nasal septa from the chimpanzee (Pan troglodytes) grossly and histologically for comparison with nasal septa from humans, Old World monkeys (Macaca fascicularis, M. nemistrina) and prosimian primates (Microcebus murinus, Otolemur garnettii). Grossly, chimpanzees had depressions on the nasal septum similar to fossae reported anterior to the VNO openings in humans. Histologically, chimpanzees and humans had bilateral epithelial tubes which were above the superior margin of the paraseptal cartilages (vomeronasal cartilage homologue). The epithelial tubes had a homogeneous ciliated epithelium. These structures were thus positionally and structurally identical to the human VNO and unlike the well-developed prosimian VNOs which were surrounded by vomeronasal cartilage. Macaques had no structures which resembled the VNO of either the prosimians or humans. The results demonstrate that the VNO is present postnatally in the chimpanzee and is almost identical to the human VNO in its anatomical position and histological structure. This in turn suggests that the reported absence of the VNO in at least some adult Old World primates is artifactual, and that further study may provide evidence for its existence in other species.

Increased levels of oxidative stress markers detected in the brains of mice devoid of prion protein

Although minor abnormalities have been reported in prion protein (PrP) knock-out (Prnp-/-) mice, the normal physiological function of PrP, the causative agent implicated in transmissible spongiform encephalopathies (TSE), remains unresolved. Since there are increasing correlations between oxidative stress and amyloidoses, we decided to investigate whether PrP plays a role in oxidative modulation. We found higher levels of oxidative damage to proteins and lipids in the brain lysates of Prnp-/- as compared to wild-type (WT) mice of the same genetic background. These two indicators, protein oxidation and lipid peroxidation, are hallmarks of cellular oxidative damage. Elevated levels of ubiquitin-protein conjugates were also observed in Prnp-/- mice, a probable consequence of cellular attempts to remove the damaged proteins as indicated by increased proteasome activity. Taken together, these findings are indicative of a role for PrP in oxidative homeostasis in vivo.

The effect of agonists and antagonists on the morphology of non-transformed human smooth muscle cell in vitro

In the present study we used scanning electron microscopy (SEM) to investigate morphological changes of non-transformed line of human bronchial smooth muscle cells (bSMC) induced by different agonists. Explants of normal bronchi were dissected and subcultured between 2 and 6 passage. In addition, smooth muscle actin content was assessed by SDS-PAGE electrophoresis, and its isoelectric point by IPG followed by immunoblotting. SMC were fixed by 2.0% paraformaldehyde and 2% glutaraldehyde and then were post-fixed by OSO4 and followed by dehydration and gold coating. Cytosolic free calcium was measured using adherent cells incubated with 500 microM Fura-2 acetoxymethylester and monitored by single excitation fluorimetry. Cultured cells possess predominantly charged actin isoforms with pI at 4.95; they respond to acetylcholine (100 microM), bradykinin (5 microM) and sulfidopeptide leukotriens (0.3-1.0 microM) with contraction, marked morphological lesions, such as widespread monolayer disorganization, extension of cell contacts. The number of microvilli on the cell surfaces was correlated with the degree of the alterations of the cellular morphology. Receptor antagonists antagonized these changes: atropine (0.3 microM), HOE 140 (1 microM) and MK 571 (1 microM). Acetylcholine and bradykinin induced a biphasic elevation of cytosolic calcium, which was antagonized by their receptor antagonists. Calcium changes in response to agonists were maintained over repetitive passages. Therefore, morphological changes seen in human bronchial SMC in culture with physiological response to various, structurally unrelated agonists can be future concern for the study the possible testing of the different pharmacological substances.

Copernicus revisited: amyloid beta in Alzheimer's disease

The beta-amyloid hypothesis of Alzheimer's Disease (AD) has dominated the thinking and research in this area for over a decade and a half. While there has been a great deal of effort in attempting to prove its centrality in this devastating disease, and while an enormous amount has been learned about its properties (e.g., putative toxicity, processing and signaling), Abeta has not proven to be both necessary and sufficient for the development, neurotoxicity, and cognitive deficits associated with this disease. Instead, the few treatments that are available have emerged from aging research and are primarily directed toward modification of acetylcholine levels. Clearly, it is time to rethink this position and to propose instead that future approaches should focus upon altering the age-related sensitivity of the neuronal environment to insults involving such factors as inflammation and oxidative stress. In other words "solve the problems of aging and by extension those of AD will also be reduced." This review is being submitted as a rather Lutherian attempt to "nail an alternative thesis" to the gate of the Church of the Holy Amyloid to open its doors to the idea that aging is the most pervasive element in this disease and Abeta is merely one of the planets.

Phosphorylated, but not native, tau protein assembles following reaction with the lipid peroxidation product, 4-hydroxy-2-nonenal

A correlation between hyperphosphorylation of tau protein and its aberrant assembly into paired helical filaments has lead to suggestions that phosphorylation controls assembly, but lacked a mechanistic basic. In this work, we have found that phosphorylated, but not native, tau protein is able to form polymers after the reaction with 4-hydroxy-2-nonenal, a highly toxic product of lipid peroxidation. Phosphorylation of tau by both proline or non-proline directed kinases, was able to assemble it into polymers.

The rational clinical examination. Does this patient have strep throat?

CONTEXT

Sore throat is a common complaint, and identifying patients with group A beta-hemolytic streptococcal pharyngitis (strep throat) is an important task for clinicians. Previous reviews have not systematically reviewed and synthesized the evidence.

OBJECTIVE

To review the precision and accuracy of the clinical examination in diagnosing strep throat.

DATA SOURCE

MEDLINE search for articles about diagnosis of strep throat using history-taking and physical examination.

STUDY SELECTION

Large blinded, prospective studies (having > or =300 patients with sore throat) reporting history and physical examination data and using throat culture as the reference standard were included. Of 917 articles identified by the search, 9 met all inclusion criteria.

DATA EXTRACTION

Pairs of authors independently reviewed each article and used consensus to resolve discrepancies.

DATA SYNTHESIS

The most useful findings for evaluating the likelihood of strep throat are presence of tonsillar exudate, pharyngeal exudate, or exposure to strep throat infection in the previous 2 weeks (positive likelihood ratios, 3.4, 2.1, and 1.9, respectively) and the absence of tender anterior cervical nodes, tonsillar enlargement, or exudate (negative likelihood ratios, 0.60, 0.63, and 0.74, respectively). No individual element of history-taking or physical examination is accurate enough by itself to rule in or rule out strep throat. Three validated clinical prediction rules are described for adult and pediatric populations.

CONCLUSIONS

While no single element of history-taking or physical examination is sufficiently accurate to exclude or diagnose strep throat, a well-validated clinical prediction rule can be useful and can help physicians make more informed use of rapid antigen tests and throat cultures.