Updated research nosology for HIV-associated neurocognitive disorders

In 1991, the AIDS Task Force of the American Academy of Neurology published nomenclature and research case definitions to guide the diagnosis of neurologic manifestations of HIV-1 infection. Now, 16 years later, the National Institute of Mental Health and the National Institute of Neurological Diseases and Stroke have charged a working group to critically review the adequacy and utility of these definitional criteria and to identify aspects that require updating. This report represents a majority view, and unanimity was not reached on all points. It reviews our collective experience with HIV-associated neurocognitive disorders (HAND), particularly since the advent of highly active antiretroviral treatment, and their definitional criteria; discusses the impact of comorbidities; and suggests inclusion of the term asymptomatic neurocognitive impairment to categorize individuals with subclinical impairment. An algorithm is proposed to assist in standardized diagnostic classification of HAND.

High-speed electrically actuated elastomers with strain greater than 100%

Electrical actuators were made from films of dielectric elastomers (such as silicones) coated on both sides with compliant electrode material. When voltage was applied, the resulting electrostatic forces compressed the film in thickness and expanded it in area, producing strains up to 30 to 40%. It is now shown that prestraining the film further improves the performance of these devices. Actuated strains up to 117% were demonstrated with silicone elastomers, and up to 215% with acrylic elastomers using biaxially and uniaxially prestrained films. The strain, pressure, and response time of silicone exceeded those of natural muscle; specific energy densities greatly exceeded those of other field-actuated materials. Because the actuation mechanism is faster than in other high-strain electroactive polymers, this technology may be suitable for diverse applications.

Catastrophic outcomes of noncardiac surgery soon after coronary stenting

OBJECTIVES

To assess the clinical course of patients who have undergone coronary stent placement less than six weeks before noncardiac surgery.

BACKGROUND

Surgical and percutaneous transluminal coronary angioplasty revascularization performed before high-risk noncardiac surgery is expected to reduce perioperative cardiac morbidity and mortality. Perioperative and postoperative complications in patients who have undergone coronary stenting before a noncardiac surgery have not been studied.

METHODS

Forty patients who underwent coronary stent placement less than six weeks before noncardiac surgery requiring a general anesthesia were included in the study (1-39 days, average: 13 days). The records were screened for the occurrence of adverse clinical events, including myocardial infarction, stent thrombosis, peri- and postoperative bleeding and death.

RESULTS

In 40 consecutive patients meeting the study criteria, there were seven myocardial infarctions (MIs), 11 major bleeding episodes and eight deaths. All deaths and MIs, as well as 8/11 bleeding episodes, occurred in patients subjected to surgery fewer than 14 days from stenting. Four patients expired after undergoing surgery one day after stenting. Based on electrocardiogram, enzymatic and angiographic evidence, stent thrombosis accounted for most of the fatal events. The time between stenting and surgery appeared to be the main determinant of outcome.

CONCLUSIONS

Postponing elective noncardiac surgery for two to four weeks after coronary stenting should permit completion of the mandatory antiplatelet regimen, thereby reducing the risk of stent thrombosis and bleeding complications.

Mechanism of nitric oxide release from S-nitrosothiols

S-Nitrosothiols have many biological activities and have been suggested to be intermediates in signal transduction. The mechanism and products of S-nitrosothiol decomposition are of great significance to the understanding of nitric oxide (.NO) biochemistry. S-Nitrosothiols are stable compounds at 37 degrees C and pH 7.4 in the presence of transition metal ion chelators. The presence of trace transition metal ions (present in all buffers) stimulates the catalytic breakdown of S-nitrosothiols to .NO and disulfide. Thiyl radicals are not formed as intermediates in this process. Photolysis of S-nitrosothiols results in the formation of .NO and disulfide via the intermediacy of thiyl radicals. Reduced metal ion (e.g. Cu+) decomposes S-nitrosothiols more rapidly than oxidized metal ion (e.g. Cu2+) indicating that reducing agents such as glutathione and ascorbate can stimulate decomposition of S-nitrosothiol by chemical reduction of contaminating transition metal ions. Transnitrosation can also stimulate S-nitrosothiol decomposition if the product S-nitrosothiol is more susceptible to transition metal ion-catalyzed decomposition than the parent S-nitrosothiol. Equilibrium constants for the transnitrosation reactions of reduced glutathione, either with S-nitroso-N-acetyl-dl-penicillamine or with S-nitroso-L-cysteine indicate that S-nitrosoglutathione formation is favored. The biological relevance of S-nitrosothiol decomposition is discussed.

Doxorubicin-induced apoptosis in endothelial cells and cardiomyocytes is ameliorated by nitrone spin traps and ebselen. Role of reactive oxygen and nitrogen species

Doxorubicin (DOX) is a broad spectrum anthracycline antibiotic used to treat a variety of cancers. Redox activation of DOX to form reactive oxygen species has been implicated in DOX-induced cardiotoxicity. In this work we investigated DOX-induced apoptosis in cultured bovine aortic endothelial cells and cardiomyocytes isolated from adult rat heart. Exposure of bovine aortic endothelial cells or myocytes to submicromolar levels of DOX induced significant apoptosis as measured by DNA fragmentation and terminal deoxynucleotidyltransferase-mediated nick-end labeling assays. Pretreatment of cells with 100 microm nitrone spin traps, N-tert-butyl-alpha-phenylnitrone (PBN) or alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) dramatically inhibited DOX-induced apoptosis. Ebselen (20-50 microm), a glutathione peroxidase mimetic, also significantly inhibited apoptosis. DOX (0.5-1 microm) inactivated mitochondrial complex I by a superoxide-dependent mechanism. PBN (100 microm), POBN (100 microm), and ebselen (50 microm) restored complex I activity. These compounds also inhibited DOX-induced caspase-3 activation and cytochrome c release. PBN and ebselen also restored glutathione levels in DOX-treated cells. We conclude that nitrone spin traps and ebselen inhibit the DOX-induced apoptotic signaling mechanism and that this antiapoptotic mechanism may be linked in part to the inhibition in formation or scavenging of hydrogen peroxide. Therapeutic strategies to mitigate DOX cardiotoxicity should be reexamined in light of these emerging antiapoptotic mechanisms of antioxidants.

Thoracic endometriosis syndrome: new observations from an analysis of 110 cases

PURPOSE

To determine the demographics, clinical presentations, pathological findings, and the effectiveness of treatment in 110 patients with thoracic endometriosis syndrome (TES).

METHODS

Retrospective analysis based on data published in the English medical literature.

RESULTS

The mean age at presentation of TES was 35 +/- 0.6 years (+/- standard error of the mean) with a range from 15 to 54. The trends of age-specific incidence for pelvic endometriosis and TES were similar. The peak incidence for pelvic endometriosis occurred between 24 and 29 years, whereas the peak incidence for TES was between 30 and 34 years. Pneumothorax was the most common presentation, occurring in 80 of 110 (73%), followed by hemothorax in 15 (14%), hemoptysis in 8 (7%), and lung nodules in 7 (6%). The right hemithorax was involved in more than 90% of all manifestations except for nodules. Hemothorax was more often associated with presence of pleural and pelvic endometriosis compared with other manifestations (P < 0.003, P < 0.02). Compared with hormonal treatment, surgical pleurodesis resulted in low recurrence rate for pneumothorax or hemothorax among patients treated with danazol or oral contraceptives.

CONCLUSIONS

There is a significant association between the presence of pelvic endometriosis and TES, with the latter occurring approximately 5 years later. Pneumothorax is the most common manifestation. The most plausible explanation for pathogenesis involves peritoneal-pleural movement of endometrial tissue through diaphragmatic defects and microembolization through pelvic veins. Diagnosis is established on clinical grounds in most cases. Surgical pleural abrasion is superior to hormonal treatment in the long-term management of pneumothorax. Earlier diagnosis and effective therapy of TES can decrease the morbidity of this disease in women during their reproductive period.

Inhibition of low-density lipoprotein oxidation by nitric oxide. Potential role in atherogenesis

The effects of nitric oxide (.NO) and nitrovasodilators on the oxidation of low-density lipoprotein (LDL) have been studied. S-Nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside (SNP) inhibited Cu(2+)- and 2,2'-azobis-2-amidinopropane hydrochloride-dependent oxidation of LDL as monitored by oxygen consumption and the formation of thiobarbituric acid-reactive substances, conjugated dienes, and lipid hydroperoxides. In the case of SNP, inhibition of LDL oxidation occurred only when the incubation mixture was irradiated with visible light. SNAP, however, exerted a dose-dependent inhibition of Cu(2+)-catalyzed oxidation of LDL even in the dark. Addition of .NO dissolved in deoxygenated buffer also inhibited the progression of LDL oxidation. Mouse peritoneal macrophages were less able to degrade LDL that had been oxidized in the presence of SNAP. Using an .NO electrode, it was estimated that a continuous production of .NO (< or = 760 nM/min) could retard the progression of LDL oxidation. We propose that .NO can inhibit LDL oxidation by acting as a chain-breaking antioxidant that is capable of scavenging carbon-centered and peroxyl radicals. Biological implications of this novel .NO antioxidant property are discussed in relation to atherogenesis and contrasted to the prooxidant property of .NO when generated in the presence of superoxide.

Synthesis and biochemical applications of a solid cyclic nitrone spin trap: a relatively superior trap for detecting superoxide anions and glutathiyl radicals

A novel cyclic nitrone spin trap, 5-tert-butoxycarbonyl 5-methyl-1-pyrroline N-oxide (BMPO) as a pure white solid has been synthesized for the first time. BMPO offers several advantages over the existing spin traps in the detection and characterization of thiyl radicals, hydroxyl radicals, and superoxide anions in biological systems. The corresponding BMPO adducts exhibit distinct and characteristic electron spin resonance (ESR) spectral patterns. Unlike the 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-derived superoxide adduct, the BMPO superoxide adduct does not non-enzymatically decompose to the BMPO hydroxyl adduct. This feature is clearly perceived as a definite advantage of BMPO in its biological applications. In addition, the ESR spectrum of the BMPO glutathionyl adduct (BMPO/*SG) does not fully overlap with the spectrum of its hydroxyl adduct. This spectral feature is again distinctly different from that of DMPO because the ESR spectral lines of DMPO glutathionyl and hydroxyl radical adducts largely overlap. Finally, the ESR spectra of BMPO-derived adducts exhibit a much higher signal-to-noise ratio in biological systems. These favorable chemical and spectroscopic features make BMPO ideal for the detection of superoxide anions, hydroxyl and thiyl radicals in biochemical oxidation and reduction.

Optical encryption by double-random phase encoding in the fractional Fourier domain

We propose an optical architecture that encodes a primary image to stationary white noise by using two statistically independent random phase codes. The encoding is done in the fractional Fourier domain. The optical distribution in any two planes of a quadratic phase system (QPS) are related by fractional Fourier transform of the appropriately scaled distribution in the two input planes. Thus a QPS offers a continuum of planes in which encoding can be done. The six parameters that characterize the QPS in addition to the random phase codes form the key to the encrypted image. The proposed method has an enhanced security value compared with earlier methods. Experimental results in support of the proposed idea are presented.

Antioxidant-rich diets improve cerebellar physiology and motor learning in aged rats

The free radical theory of aging predicts that reactive oxygen species are involved in the decline in function associated with aging. The present paper reports that diets supplemented with either spinach, strawberries or blueberries, nutritional sources of antioxidants, reverse age-induced declines in beta-adrenergic receptor function in cerebellar Purkinje neurons measured using electrophysiological techniques. In addition the spinach diet improved learning on a runway motor task, previously shown to be modulated by cerebellar norepinephrine. Motor learning is important for adaptation to changes in the environment and is thus critical for rehabilitation following stroke, spinal cord injury, and the onset of some neurodegenerative diseases. These data are the first to indicate that age-related deficits in motor learning and memory can be reversed with nutritional interventions.

Effects of neurotransmitters on the chemokinesis and chemotaxis of MDA-MB-468 human breast carcinoma cells

Most patients suffering from breast carcinoma do not die due to the primary tumor but from the development of metastases. Active migration of cancer cells is a prerequisite for development of these metastases. We used time-lapse videomicroscopy and computer-assisted cell tracking of MDA-MB-468 human breast carcinoma cells, which were incorporated into a three-dimensional collagen matrix, in order to analyze the migratory activity of these cells in response to different neurotransmitters. Our results show that met-enkephalin, substance P, bombesin, dopamine, and norepinephrine have a stimulatory effect on the migration of the breast cancer cells; moreover, these cells show positive chemotaxis towards norepinephrine as was analyzed by the directionality and persistence on a single-cell basis. Gamma-aminobutyric acid (GABA) however has an inhibitory effect. Endorphin and leu-enkephalin, as well as histamin and acetylcholine, had no influence on the migratory activity of the cells. In summary, we provide evidence for a strong regulatory involvement of neurotransmitters in the regulation of breast cancer cell migration, which might provide the basis for the use of the pharmacological agonists and antagonists for the chemopreventive inhibition of metastasis development.

NEAR at eros: imaging and spectral results

Eros is a very elongated (34 kilometers by 11 kilometers by 11 kilometers) asteroid, most of the surface of which is saturated with craters smaller than 1 kilometer in diameter. The largest crater is 5.5 kilometers across, but there is a 10-kilometer saddle-like depression with attributes of a large degraded crater. Surface lineations, both grooves and ridges, are prominent on Eros; some probably exploit planes of weakness produced by collisions on Eros and/or its parent body. Ejecta blocks (30 to 100 meters across) are abundant but not uniformly distributed over the surface. Albedo variations are restricted to the inner walls of certain craters and may be related to downslope movement of regolith. On scales of 200 meters to 1 kilometer, Eros is more bland in terms of color variations than Gaspra or Ida. Spectra (800 to 2500 nanometers) are consistent with an ordinary chondrite composition for which the measured mean density of 2.67 +/- 0.1 grams per cubic centimeter implies internal porosities ranging from about 10 to 30 percent.

Relapses in multiple sclerosis are age- and time-dependent

OBJECTIVES

To examine the relative relapse-rate patterns over time in a relapsing multiple sclerosis (MS) cohort and to investigate potential predictors of relapse rates and periods of low-relapse activity.

METHODS

This retrospective cohort study followed 2477 relapsing-remitting (RR) MS patients from onset to 1 July 2003. Annualised relapse rates were examined according to sex, age at onset, the patient's current age and disease duration. The relationship between relapse rates and baseline characteristics (sex, onset age and onset symptoms) were examined using Poisson regression. Time to the first 5 years relapse-free was examined using Kaplan-Meier survival analysis.

RESULTS

The mean follow-up time (from onset of MS symptoms) was 20.6 years, during which time 11,722 post-onset relapses were recorded. The relapse rate decreased by 17% every 5 years (between years 5 to 30 post-onset), but this decline increased in magnitude with increasing onset age. Women and those with onset sensory symptoms exhibited a higher relapse rate (p< or =0.001). More than three-quarters of patients (1692/2189) experienced a 5-year relapse-free period during the RR phase.

CONCLUSION

Relapse rates were age- and time-dependent. Our observations have clinical implications: 1) any drug able to modify relapse rates has the greatest potential for a population impact in patients <40 years old and within the first few demi-decades of disease; 2) continuation of drug beyond these times may be of limited value; 3) long-term follow-up studies must consider that relapse rates probably decline at different rates over time according to the patient's onset age; 4) a relapse-quiescent period in MS is not uncommon.

Increased circulating platelet-leucocyte complexes and platelet activation in patients with antiphospholipid syndrome, systemic lupus erythematosus and rheumatoid arthritis

It is possible that platelet activation may play a pathogenic role in the increased risk of thrombosis associated with antiphospholipid antibodies (APA). In this study, levels of in vivo platelet activation were measured in 20 patients with primary antiphospholipid syndrome (PAPS) and 30 systemic lupus erythematosus (SLE) patients (14 of whom had secondary APS) using sensitive flow cytometry. Soluble P-selectin levels were also assayed. Platelet CD63 expression was significantly higher in PAPS than normal controls (P = 0.007), as well as SLE patients with and without secondary APS (P = 0.03 and P = 0.002 respectively). PAC-1 binding was significantly higher in PAPS than the control group (P = 0.007) and SLE patients without APS (P = 0.015). Platelet-leucocyte complexes were significantly higher in SLE patients than both PAPS and the control group, and platelet-monocyte complexes were significantly increased in PAPS compared with the control group. (Platelet-leucocyte complexes were also significantly higher than controls in 10 rheumatoid arthritis (RA) patients without APA). Soluble P-selectin levels were significantly higher in PAPS and SLE patients than the control group. Platelet CD62p expression, annexin V binding and platelet microparticle numbers were not increased in PAPS or SLE patients. We conclude that there is evidence of increased platelet activation in PAPS and SLE, and this is important to note as it may have potential therapeutic implications with respect to use of antiplatelet agents in these patients.

Prevalence of serious eye disease and visual impairment in a north London population: population based, cross sectional study

OBJECTIVE

To estimate the magnitude of serious eye disorders and of visual impairment in a defined elderly population of a typical metropolitan area in England, and to assess the frequency they were in touch with, or known to, the eye care services.

DESIGN

Cross sectional survey using two stage cluster random sampling.

SETTING

General practices in north London.

SUBJECTS

Random sample of people aged 65 and older, drawn from a defined population of elderly people registered with 17 general practice groups.

MAIN OUTCOME MEASURES

Proportions and population prevalence estimates were determined for visual acuity, assessed with the person's own spectacles (if any), classified into four categories: prevalence of cataract, age related macular degeneration, and refractive error causing visual impairment and of definite primary open angle glaucoma; and status of contact with eye services.

RESULTS

1547 of 1840 (84%) eligible people were examined. The population prevalence of bilateral visual impairment (visual acuity <6/12) was 30%, of which 72% was potentially remediable. 92 of these 448 cases (21%) had visual acuity <6/60 ("blindness") in one or both eyes. Prevalence of cataract causing visual impairment was 30%; 88% of these people were not in touch with the eye services. The prevalence of vision impairing, age related macular degeneration was 8% and of glaucoma (definite cases) was 3%. Three quarters of the people with definite glaucoma were not known to the eye services.

CONCLUSIONS

Untreated visual impairment and eye disorders affect a substantial proportion of people aged 65 years and older. These findings should contribute to the setting up of future strategies for preservation of sight and eye health services in general.

Doxorubicin-induced apoptosis is associated with increased transcription of endothelial nitric-oxide synthase. Effect of antiapoptotic antioxidants and calcium

The clinical efficacy of the antitumor antibiotic drug doxorubicin (DOX) is severely limited by its dose-limiting cardiotoxicity in cancer patients. DOX-induced generation of reactive oxygen species was proposed to be a major mechanism of its cardiotoxicity. Previously, we showed that DOX undergoes a reductive activation at the reductase domain of endothelial nitric-oxide synthase (eNOS) forming the semiquinone and superoxide (Vásquez-Vivar, J., Martasek, P., Hogg, N., Masters, B. S. S., Pritchard, K. A., Jr., and Kalyanaraman, B. (1997) Biochemistry 36, 11293-11297). In this report, we provide evidence for DOX-induced increase in eNOS transcription and protein expression in bovine aortic endothelial cells (BAEC). We propose that DOX-induced hydrogen peroxide formation is responsible for the increased transcription of eNOS. BAEC treated with antisense eNOS oligonucleotide inhibits DOX-induced endothelial apoptosis. Treatment with antioxidants restored the levels of antiapoptotic proteins (Hsp70 and Bcl-2) in DOX-treated BAEC. DOX-induced intracellular oxidative stress, as measured by oxidation of dichlorodihydrofluorescein diacetate to dichlorofluorescein and hydroethidium to ethidium, was inhibited by antisense eNOS oligonucleotide and antioxidant treatment. Furthermore, antiapoptotic antioxidants (e.g. FeTBAP, ebselen, and alpha-phenyl-tert-butyl nitrone) inhibited DOX-induced eNOS transcription. We conclude that DOX-induced apoptosis is linked to the redox activation of DOX by eNOS.

The landing of the NEAR-Shoemaker spacecraft on asteroid 433 Eros

The NEAR-Shoemaker spacecraft was designed to provide a comprehensive characterization of the S-type asteroid 433 Eros (refs 1,2,3), an irregularly shaped body with approximate dimensions of 34 x 13 x 13 km. Following the completion of its year-long investigation, the mission was terminated with a controlled descent to its surface, in order to provide extremely high resolution images. Here we report the results of the descent on 12 February 2001, during which 70 images were obtained. The landing area is marked by a paucity of small craters and an abundance of 'ejecta blocks'. The properties and distribution of ejecta blocks are discussed in a companion paper. The last sequence of images reveals a transition from the blocky surface to a smooth area, which we interpret as a 'pond'. Properties of the 'ponds' are discussed in a second companion paper. The closest image, from an altitude of 129 m, shows the interior of a 100-m-diameter crater at 1-cm resolution.

Thalamic integrity underlies executive dysfunction in traumatic brain injury

OBJECTIVE

To quantify the effects of traumatic brain injury on integrity of thalamocortical projection fibers and to evaluate whether damage to these fibers accounts for impairments in executive function in chronic traumatic brain injury.

METHODS

High-resolution (voxel size: 0.78 mm x 0.78 mm x 3 mm(3)) diffusion tensor MRI of the thalamus was conducted on 24 patients with a history of single, closed-head traumatic brain injury (TBI) (12 each of mild TBI and moderate to severe TBI) and 12 age- and education-matched controls. Detailed neuropsychological testing with an emphasis on executive function was also conducted. Fractional anisotropy was extracted from 12 regions of interest in cortical and corpus callosum structures and 7 subcortical regions of interest (anterior, ventral anterior, ventral lateral, dorsomedial, ventral posterior lateral, ventral posterior medial, and pulvinar thalamic nuclei).

RESULTS

Relative to controls, patients with a history of brain injury showed reductions in fractional anisotropy in both the anterior and posterior corona radiata, forceps major, the body of the corpus callosum, and fibers identified from seed voxels in the anterior and ventral anterior thalamic nuclei. Fractional anisotropy from cortico-cortico and corpus callosum regions of interest did not account for significant variance in neuropsychological function. However, fractional anisotropy from the thalamic seed voxels did account for variance in executive function, attention, and memory.

CONCLUSIONS

The data provide preliminary evidence that traumatic brain injury and resulting diffuse axonal injury results in damage to the thalamic projection fibers and is of clinical relevance to cognition.

NEAR's flyby of 253 mathilde: images of a C asteroid

On 27 June 1997, the Near Earth Asteroid Rendezvous (NEAR) spacecraft flew within 1212 kilometers of asteroid 253 Mathilde. Mathilde is an irregular, heavily cratered body measuring 66 kilometers by 48 kilometers by 46 kilometers. The asteroid's surface is dark (estimated albedo between 0.035 and 0.050) and similar in color to some CM carbonaceous chondrites. No albedo or color variations were detected. The volume derived from the images and the mass from Doppler tracking of the spacecraft yield a mean density of 1.3 +/- 0.2 grams per cubic centimeter, about half that of CM chondrites, indicating a porous interior structure.

Linear accelerator-based stereotaxic radiosurgery for brain metastases:the influence of number of lesions on survival

PURPOSE

To evaluate the influence of the number of brain metastases on survival after stereotaxic radiosurgery and factors that affect the risk of delayed radiation necrosis after treatment.

MATERIALS AND METHODS

Between March 1989 and December 1993, 120 consecutive patients underwent linear accelerator-based stereotaxic radiosurgery for brain metastases identified by computed tomography (CT) or magnetic resonance imaging (MRI) scans. The influence of various clinical factors on outcome was assessed using Kaplan-Meier plots of survival from the date of radiosurgery, and univariate and multivariate analyses.

RESULTS

The median survival time was 32 weeks. Progressive brain metastases, both local and regional, caused 25 of 104 deaths. Patients with two metastases (n = 30) or a solitary metastasis (n = 70) had equivalent actuarial survival times (P = .07; median, 37 weeks; maximum, 211+ weeks). Patients treated to three or more metastases (n = 20) had significantly shorter survival times (P < .002; median, 14 weeks; maximum, 63 weeks). Prognostic factors associated with prolonged survival included a pretreatment Karnofsky performance status > or = 70% and fewer than three metastases. Delayed radiation necrosis at the treated site developed in 20 patients and correlated with prior or concurrent delivery of whole-brain irradiation and the logarithm of the tumor volume.

CONCLUSION

Survival duration is equivalent for patients with one or two brain metastases and is similar to that reported for patients with a solitary metastasis managed by surgical resection and whole-brain irradiation. Survival after radiosurgery for three or more metastases was similar to that reported for whole-brain irradiation.

Molecular pathway involved in HIV-1-induced CNS pathology: role of viral regulatory protein, Tat

The broad range of histological lesions associated with HIV-1 are somewhat subtle relative to the clinical manifestations that occur as a result of HIV infection. Although it is clear that HIV has a causative role in CNS disease, dementia appears to be a consequence of the infiltration of inflammatory cells and cytokine dysregulation rather than the amount of virus in CNS. The HIV transregulatory protein Tat plays an important intracellular as well as extracellular role in the dysregulation of cytokines. The cytokines and possibly chemokines that are induced by Tat modify the action of astrocytes such that the survival of neurons is compromised. Pathogenetic alteration induced by Tat involves a series of interactions between circulating monocyte/macrophages, endothelial cells, and astrocytes. Cytokine dysregulation induced by viral infection and extracellular Tat leads to alterations in expression of adhesion molecules and promotes migration of non-infected inflammatory cells into the CNS compartment. We demonstrate here that recombinant HIV-1 Tat protein introduced by stereotaxic injection into mouse brain can induce pathologically relevant alterations including macrophage invasion as well as astrocytosis. The mechanism of destruction of the CNS by Tat appears to involve autocrine and paracrine pathways that depend not only on Tat, but cytokine and chemokine signaling pathways that are altered by viral infection. In this review, we discuss various pathogenic effects of Tat in brain cells and provide experimental evidence for an increased TNF-alpha level in CSF in mice injected intracerebrally with Tat protein.

Pancam multispectral imaging results from the Spirit Rover at Gusev Crater

Panoramic Camera images at Gusev crater reveal a rock-strewn surface interspersed with high- to moderate-albedo fine-grained deposits occurring in part as drifts or in small circular swales or hollows. Optically thick coatings of fine-grained ferric iron-rich dust dominate most bright soil and rock surfaces. Spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near-infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine. Atmospheric observations show a steady decline in dust opacity during the mission, and astronomical observations captured solar transits by the martian moons, Phobos and Deimos, as well as a view of Earth from the martian surface.

Detection of superoxide anion using an isotopically labeled nitrone spin trap: potential biological applications

We describe the synthesis and biological applications of a novel nitrogen-15-labeled nitrone spin trap, 5-ethoxycarbonyl-5-methyl-1-pyrroline N-oxide ([(15)N]EMPO) for detecting superoxide anion. Superoxide anion generated in xanthine/xanthine oxidase (100 nM min(-1)) and NADPH/calcium-calmodulin/nitric oxide synthase systems was readily detected using EMPO, a nitrone analog of 5,5'-dimethyl-1-pyrroline N-oxide (DMPO). Unlike DMPO-superoxide adduct (DMPO-OOH), the superoxide adduct of EMPO (EMPO-OOH) does not spontaneously decay to the corresponding hydroxyl adduct, making spectral interpretation less confounding. Although the superoxide adduct of 5-(diethoxyphosphoryl)-5-methyl-pyrroline N-oxide is more persistent than EMPO-OOH, the electron spin resonance spectra of [(14)N]EMPO-OOH and [(15)N]EMPO-OOH are less complex and easier to interpret. Potential uses of [(15)N]EMPO in elucidating the mechanism of superoxide formation from nitric oxide synthases, and in ischemia/reperfusion injury are discussed.

Expression of organ-specific antigens on capillary endothelial cells

Our central thesis is that the endothelial cells which line capillaries of various organs are not all alike. Using monoclonal and conventional antibodies we demonstrate that capillary endothelial cells express on their cell surface an array of antigens that manifest organ selectivity. Brain-derived endothelial cells possess brain-associated antigens, ovary-derived endothelial cells share antigenic markers with other ovarian cells, and lung-derived endothelium possesses antigens that are primarily expressed on cells of the lung. Our experiments lead us to suggest that organ-associated determinants on the endothelial cell surface may play a role in the selective adhesion of tumor cells during metastasis, in site-limited vascular pathology, and in the regionally limited release of angiogenesis-induced factors.

HIV-related symptoms and psychological functioning in a cohort of homosexual men

The authors administered the Center for Epidemiological Studies Depression (CES-D) Scale to 4,954 homosexual men in the Multicenter AIDS Cohort Study. HIV antibody status at enrollment was a less important predictor of psychological distress than were reported physical symptoms. Multivariate analysis showed an association between a high score on each CES-D Scale component and the number of self-reported possible AIDS- or HIV-related symptoms, perceived lymphadenopathy, and absence of "someone to talk to about serious problems." This relationship between self-reported physical symptoms and psychological distress suggests a possible etiologic relationship between perceived AIDS risk and psychological symptoms in men at risk of AIDS.