bluuebunny/crossref_metadata_2025 huggingface dataset:
The distribution of the anti-HIV drug, tenofovir (PMPA), into the brain, CSF and choroid plexuses
Authors: Anthonypillai Christy , Gibbs Julie E , Thomas Sarah A
Published: January 2006

Background

Tenofovir disoproxil fumarate, a prodrug of the nucleotide reverse transcriptase inhibitor, tenofovir (9-[9(R)-2-(phosphonomethoxy)propyl]adenine; PMPA), was recently approved for use in the combination therapy of human immunodeficiency virus (HIV)-1 infection. This study was undertaken to understand PMPA distribution to the virus sanctuary sites located in the brain, CSF and choroid plexuses and to clarify its possible role in reducing the neurological problems associated with HIV infection.

Methods

The methods used included an established bilateral carotid artery perfusion of [3H]PMPA and a vascular marker, D-[14C]mannitol, in anaesthetised guinea-pigs followed by scintillation counting, HPLC and capillary depletion analyses. Movement of [3H]PMPA into the brain, cisternal CSF and lateral ventricle choroid plexus was also examined in the absence and presence of additional anti-HIV drugs and a transport inhibitor. Control and test groups were compared by ANOVA or Student'st-test, as appropriate.

Results

The distribution of [3H]PMPA in the cerebrum, cerebellum, pituitary gland and cerebral capillary endothelial cells was not significantly different to that measured for D-[14C]mannitol. However, [3H]PMPA accumulation was significantly higher than that of D-[14C]mannitol in the choroid plexus and CSF. Further experiments revealed no cross-competition for transport of [3H]PMPA by probenecid, a non-specific inhibitor of organic anion transport, or the nucleoside reverse transcriptase inhibitors into any of the CNS regions studied. The octanol-saline partition coefficient measurement for [3H]PMPA was 0.0134 ± 0.00003, which is higher that the 0.002 ± 0.0004 measured for D-[14C]mannitol in an earlier study.

Conclusion

There is negligible transport of [3H]PMPA across the blood-brain barrier, but it can cross the blood-CSF barrier. This is a reflection of the differing physiological and functional characteristics of the blood-CNS interfaces. Self- and cross-inhibition studies did not suggest the involvement of a transport system in the CNS distribution of this drug. However, the ability of PMPA to accumulate in the choroid plexus tissue, but not the cerebral capillary endothelial cells, and the hydrophilic nature of PMPA, does point to the possibility of a transporter at the level of the choroid plexus. PMPA that has crossed the choroid plexus and is in the CSF could treat HIV-infected perivascular and meningeal macrophages, but it is unlikely to reach the infected microglia of deep brain sites.
Physicochemical characterisation of combustion particles from vehicle exhaust and residential wood smoke
Authors: Kocbach Anette , Li Yanjun , Yttri Karl E , Cassee Flemming R , Schwarze Per E , Namork Ellen
Published: January 2006

Background

Exposure to ambient particulate matter has been associated with a number of adverse health effects. Particle characteristics such as size, surface area and chemistry seem to influence the negative effects of particles. In this study, combustion particles from vehicle exhaust and wood smoke, currently used in biological experiments, were analysed with respect to microstructure and chemistry.

Methods

Vehicle exhaust particles were collected in a road tunnel during two seasons, with and without use of studded tires, whereas wood smoke was collected from a stove with single-stage combustion. Additionally, a reference diesel sample (SRM 2975) was analysed. The samples were characterised using transmission electron microscopy techniques (TEM/HRTEM, EELS and SAED). Furthermore, the elemental and organic carbon fractions were quantified using thermal optical transmission analysis and the content of selected PAHs was determined by gas chromatography-mass spectrometry.

Results

Carbon aggregates, consisting of tens to thousands of spherical primary particles, were the only combustion particles identified in all samples using TEM. The tunnel samples also contained mineral particles originating from road abrasion. The geometric diameters of primary carbon particles from vehicle exhaust were found to be significantly smaller (24 ± 6 nm) than for wood smoke (31 ± 7 nm). Furthermore, HRTEM showed that primary particles from both sources exhibited a turbostratic microstructure, consisting of concentric carbon layers surrounding several nuclei in vehicle exhaust or a single nucleus in wood smoke. However, no differences were detected in the graphitic character of primary particles from the two sources using SAED and EELS. The total PAH content was higher for combustion particles from wood smoke as compared to vehicle exhaust, whereas no source difference was found for the ratio of organic to total carbon.

Conclusion

Combustion particles from vehicle exhaust and residential wood smoke differ in primary particle diameter, microstructure, and PAH content. Furthermore, the analysed samples seem suitable for assessing the influence of physicochemical characteristics of particles on biological responses.
Imbalance of local bone metabolism in inflammatory arthritis and its reversal upon tumor necrosis factor blockade: direct analysis of bone turnover in murine arthritis
Authors: Zwerina Jochen , Tuerk Birgit , Redlich Kurt , Smolen Josef S , Schett Georg
Published: January 2006

Chronic arthritis typically leads to loss of periarticular bone, which results from an imbalance between bone formation and bone resorption. Recent research has focused on the role of osteoclastogenesis and bone resorption in arthritis. Bone resorption cannot be observed isolated, however, since it is closely linked to bone formation and altered bone formation may also affect inflammatory bone loss. To simultaneously assess bone resorption and bone formation in inflammatory arthritis, we developed a histological technique that allows visualization of osteoblast function by in-situ hybridization for osteocalcin and osteoclast function by histochemistry for tartrate-resistant acid phosphatase. Paw sections from human tumor necrosis factor transgenic mice, which develop an erosive arthritis, were analyzed at three different skeletal sites: subchondral bone erosions, adjacent cortical bone channels, and endosteal regions distant from bone erosions. In subchondral bone erosions, osteoclasts were far more common than osteoblasts. In contrast, cortical bone channels underneath subchondral bone erosions showed an accumulation of osteoclasts but also of functional osteoblasts resembling a status of high bone turnover. In contrast, more distant skeletal sites showed only very low bone turnover with few scattered osteoclasts and osteoblasts. Within subchondral bone erosions, osteoclasts populated the subchondral as well as the inner wall, whereas osteoblasts were almost exclusively found along the cortical surface. Blockade of tumor necrosis factor reversed the negative balance of bone turnover, leading to a reduction of osteoclast numbers and enhanced osteoblast numbers, whereas the blockade of osteoclastogenesis by osteoprotegerin also abrogated the osteoblastic response. These data indicate that bone resorption dominates at skeletal sites close to synovial inflammatory tissue, whereas bone formation is induced at more distant sites attempting to counter-regulate bone resorption.
Vitamin D receptor gene polymorphisms and susceptibility of hand osteoarthritis in Finnish women
Authors: Solovieva Svetlana , Hirvonen Ari , Siivola Päivi , Vehmas Tapio , Luoma Katariina , Riihimäki Hilkka , Leino-Arjas Päivi
Published: January 2006

We examined whether polymorphisms of the vitamin D receptor (VDR) gene was associated with individual risk of hand osteoarthritis (OA). Radiographs of both hands of 295 dentists and of 248 teachers were examined and classified for the presence of OA using reference images. The VDR ApaI and TaqI genotypes were determined by PCR-based methods. No association was observed between the VDR polymorphisms and the odds of overall hand OA. However, the carriers of the VDR t allele or At haplotype were at almost half the odds of symmetrical hand OA (odds ratio [OR] = 0.60, 95% confidence interval [CI] = 0.38–0.94 and OR = 0.59, 95% CI = 0.38–0.93, respectively) compared with the carriers of the T allele and of the non-At haplotype, respectively. Increased odds of this disease, on the contrary, was observed for women with two copies of the VDR a allele (OR = 1.93, 95% CI = 1.99–3.70) compared with women with the AA genotype. Conversely, the VDR a allele carriage was associated with a tendency of lowered odds of osteophyte (OR = 0.51, 95% CI = 0.25–1.03). When the genotype data were used to construct haplotypes, the VDR AaTt joint genotype appeared to pose a remarkably lower odds (OR = 0.26, 95% CI = 0.08–0.91) of osteophyte compared with the AAtt joint genotype. As a novel finding we observed a joint effect of a low calcium intake and VDR polymorphisms on symmetrical OA; the OR was 2.64 (95% CI = 1.29–5.40) for carriers of the aT haplotype with low daily calcium intake compared with non-carriers of the haplotype with high daily calcium intake. Our results suggest that VDR gene polymorphisms play a role in the etiology of symmetrical hand OA. Moreover, the association between the VDR gene and OA may be modified by calcium intake.
Fibroblast activation protein alpha is expressed by chondrocytes following a pro-inflammatory stimulus and is elevated in osteoarthritis
Authors: Milner Jennifer M , Kevorkian Lara , Young David A , Jones Debra , Wait Robin , Donell Simon T , Barksby Emma , Patterson Angela M , Middleton Jim , Cravatt Benjamin F , Clark Ian M , Rowan Andrew D , Cawston Timothy E
Published: January 2006

Arthritis is characterised by the proteolytic degradation of articular cartilage leading to a loss of joint function. Articular cartilage is composed of an extracellular matrix of proteoglycans and collagens. We have previously shown that serine proteinases are involved in the activation cascades leading to cartilage collagen degradation. The aim of this study was to use an active-site probe, biotinylated fluorophosphonate, to identify active serine proteinases present on the chondrocyte membrane after stimulation with the pro-inflammatory cytokines IL-1 and oncostatin M (OSM), agents that promote cartilage resorption. Fibroblast activation protein alpha (FAPα), a type II integral membrane serine proteinase, was identified on chondrocyte membranes stimulated with IL-1 and OSM. Real-time PCR analysis shows that FAPα gene expression is up-regulated by this cytokine combination in both isolated chondrocytes and cartilage explant cultures and is significantly higher in cartilage from OA patients compared to phenotypically normal articular cartilage. Immunohistochemistry analysis shows FAPα expression on chondrocytes in the superficial zone of OA cartilage tissues. This is the first report demonstrating the expression of active FAPα on the chondrocyte membrane and elevated levels in cartilage from OA patients. Its cell surface location and expression profile suggest that it may have an important pathological role in the cartilage turnover prevalent in arthritic diseases.
Hip joint replacement surgery for idiopathic osteoarthritis aggregates in families
Authors: Bukulmez H , Matthews AL , Sullivan CM , Chen C , Kraay MJ , Elston RC , Moskowitz RW , Goldberg VM , Warman ML
Published: January 2006

In order to determine whether there is a genetic component to hip or knee joint failure due to idiopathic osteoarthritis (OA), we invited patients (probands) undergoing hip or knee arthroplasty for management of idiopathic OA to provide detailed family histories regarding the prevalence of idiopathic OA requiring joint replacement in their siblings. We also invited their spouses to provide detailed family histories about their siblings to serve as a control group. In the probands, we confirmed the diagnosis of idiopathic OA using American College of Rheumatology criteria. The cohorts included the siblings of 635 probands undergoing total hip replacement, the siblings of 486 probands undergoing total knee replacement, and the siblings of 787 spouses. We compared the prevalence of arthroplasty for idiopathic OA among the siblings of the probands with that among the siblings of the spouses, and we used logistic regression to identify independent risk factors for hip and knee arthroplasty in the siblings. Familial aggregation for hip arthroplasty, but not for knee arthroplasty, was observed after controlling for age and sex, suggesting a genetic contribution to end-stage hip OA but not to end-stage knee OA. We conclude that attempts to identify genes that predispose to idiopathic OA resulting in joint failure are more likely to be successful in patients with hip OA than in those with knee OA.
Association of functional variants of PTPN22 and tp53in psoriatic arthritis: a case-control study
Authors: Butt Christopher , Peddle Lynette , Greenwood Celia , Hamilton Sean , Gladman Dafna , Rahman Proton
Published: January 2006

Recent studies have implicated PTPN22 and tp53 in susceptibility to several autoimmune diseases, including rheumatoid arthritis, suggesting that these genes are important in maintaining immune homeostasis. Because autoimmune diseases may share similar susceptibility loci, investigation of these genes in psoriatic arthritis (PsA) is of potential relevance. As a result we investigated known coding polymorphisms in PTPN22 and tp53 in a homogenous Caucasian PsA cohort from Newfoundland, Canada and an admixed Caucasian PsA cohort from Toronto, Canada. We observed a moderate association of the R620W variant of PTPN22 with PsA in the Toronto population only. Because of the conflicting findings reported regarding the association of PTPN22 with PsA, further studies in other PsA populations are warranted.
Comprehensive copy number profiles of breast cancer cell model genomes
Authors: Shadeo Ashleen , Lam Wan L
Published: January 2006

Introduction

Breast cancer is the most commonly diagnosed cancer in women worldwide and consequently has been extensively investigated in terms of histopathology, immunochemistry and familial history. Advances in genome-wide approaches have contributed to molecular classification with respect to genomic changes and their subsequent effects on gene expression. Cell lines have provided a renewable resource that is readily used as model systems for breast cancer cell biology. A thorough characterization of their genomes to identify regions of segmental DNA loss (potential tumor-suppressor-containing loci) and gain (potential oncogenic loci) would greatly facilitate the interpretation of biological data derived from such cells. In this study we characterized the genomes of seven of the most commonly used breast cancer model cell lines at unprecedented resolution using a newly developed whole-genome tiling path genomic DNA array.

Methods

Breast cancer model cell lines MCF-7, BT-474, MDA-MB-231, T47D, SK-BR-3, UACC-893 and ZR-75-30 were investigated for genomic alterations with the submegabase-resolution tiling array (SMRT) array comparative genomic hybridization (CGH) platform. SMRT array CGH provides tiling coverage of the human genome permitting break-point detection at about 80 kilobases resolution. Two novel discrete alterations identified by array CGH were verified by fluorescence in situ hybridization.

Results

Whole-genome tiling path array CGH analysis identified novel high-level alterations and fine-mapped previously reported regions yielding candidate genes. In brief, 75 high-level gains and 48 losses were observed and their respective boundaries were documented. Complex alterations involving multiple levels of change were observed on chromosome arms 1p, 8q, 9p, 11q, 15q, 17q and 20q. Furthermore, alignment of whole-genome profiles enabled simultaneous assessment of copy number status of multiple components of the same biological pathway. Investigation of about 60 loci containing genes associated with the epidermal growth factor family (epidermal growth factor receptor, HER2, HER3 and HER4) revealed that all seven cell lines harbor copy number changes to multiple genes in these pathways.

Conclusion

The intrinsic genetic differences between these cell lines will influence their biologic and pharmacologic response as an experimental model. Knowledge of segmental changes in these genomes deduced from our study will facilitate the interpretation of biological data derived from such cells.
Co-expression of estrogen receptor-alpha and targets of estrogen receptor action in proliferating monkey mammary epithelial cells
Authors: Dimitrakakis Constantine , Zhou Jian , Wang Jie , Matyakhina Ludmila , Mezey Eva , Xiyu Wood Jesse , Wang Daniel , Bondy Carolyn
Published: January 2006

Introduction

Failure to detect co-expression of estrogen receptor-alpha (ERα) and proliferation 'markers' such as Ki67 in human mammary epithelium led to the view that estrogen acts indirectly to stimulate mammary epithelial proliferation. The mitotic index was so low in prior studies, however, that transient co-expression of ERα and Ki67 during the cell cycle could have been below detection limits.

Methods

Immunohistochemistry was used on mammary tissue sections from estrogen treated rhesus monkeys to investigate co-expression of ERα and the proliferation antigen Ki67. Using the same methods, we investigated the cell localization of proteins involved in estrogen-induced proliferation, including cyclin D1, stromal cell-derived factor (SDF)-1, and MYC.

Results

ERα was co-expressed with the proliferation marker Ki67 as well as with SDF-1, MYC and cyclin D1 in mammary epithelial cells from estrogen-treated monkeys.

Conclusion

ERα is expressed in proliferating mammary epithelial cells together with the estrogen-induced proteins MYC, cyclin D1 and SDF-1, consistent with a direct mitogenic action by estrogen in primate mammary epithelium.
The undertranslated transcriptome reveals widespread translational silencing by alternative 5' transcript leaders
Authors: Law G Lynn , Bickel Kellie S , MacKay Vivian L , Morris David R
Published: January 2006

Background

Translational efficiencies in Saccharomyces cerevisiae vary from transcript to transcript by approximately two orders of magnitude. Many of the poorly translated transcripts were found to respond to the appropriate external stimulus by recruiting ribosomes. Unexpectedly, a high frequency of these transcripts showed the appearance of altered 5' leaders that coincide with increased ribosome loading.

Results

Of the detectable transcripts in S. cerevisiae, 8% were found to be underloaded with ribosomes. Gene ontology categories of responses to stress or external stimuli were overrepresented in this population of transcripts. Seventeen poorly loaded transcripts involved in responses to pheromone, nitrogen starvation, and osmotic stress were selected for detailed study and were found to respond to the appropriate environmental signal with increased ribosome loading. Twelve of these regulated transcripts exhibited structural changes in their 5' transcript leaders in response to the environmental signal. In many of these the coding region remained intact, whereas regulated shortening of the 5' end truncated the open reading frame in others. Colinearity between the gene and transcript sequences eliminated regulated splicing as a mechanism for these alterations in structure.

Conclusion

Frequent occurrence of coordinated changes in transcript structure and translation efficiency, in at least three different gene regulatory networks, suggests a widespread phenomenon. It is likely that many of these altered 5' leaders arose from changes in promoter usage. We speculate that production of translationally silenced transcripts may be one mechanism for allowing low-level transcription activity necessary for maintaining an open chromatin structure while not allowing inappropriate protein production.
Avoiding a spiral of precaution in mental healthcare
Authors: Green Jonathan
Published: January 2006

The precautionary principle has high face validity, but it can favour indeterminate future risks over potential current benefits. It can also have unintended consequences when applied to the design of clinical protocols and health policy. Contemporary pressures in mental healthcare may amplify the precautionary principle in practice. To mitigate against these disadvantages, we need trial designs that assess all risks (including the risk of no treatment) and also the possibility that potential risks may be successfully managed. Critical appraisal of clinical protocols and their impact are also necessary.
Advances in neuropsychiatry: clinical implications
Authors: Dilley Mike , Fleminger Simon
Published: January 2006

In this review of recent advances in the sub-specialty, we briefly discuss the current understanding of causes, presentations and evidence-based treatment of the most common disorders seen in clinical neuropsychiatry. Traumatic and acquired brain injury, epilepsy, multiple sclerosis, Parkinson's and Huntington's disease, sleep disorders and delirium are all considered, focusing on the most contentious issues and practical approaches to management and treatment.
Sudden cardiac death and antipsychotics. Part 1: Risk factors and mechanisms
Authors: Abdelmawla Nasser , Mitchell Alex J.
Published: January 2006

Mortality from causes other than suicide is higher than expected in schizophrenia. Cardiovascular causes are most common, accounting for the majority of the 5% of sudden and unexpected deaths. Most cases have no clear explanation on post-mortem examination (‘sudden unexplained deaths’) and are thought to result from fatal arrhythmias. Prospective studies show that people with prolongation of the QT interval beyond 500 ms are at increased risk of serious arrhythmias such as ventricular tachycardia and torsade de pointes. In about 1 in 10 cases, the torsade is fatal. Most antipsychotics prolong the QTc interval in overdose but some prolong it even at therapeutic doses. Droperidol, sertindole and ziprasidone extend the QT interval by an average of 15–35 ms; quetiapine, haloperidol and olanzapine by 5 ms, to 15 ms. There is only an approximate relationship between QT prolongation and risk of sudden death, and the risk related to antipsychotics is thought to increase in people with pre-existing cardiac disease, those taking multiple QT-acting drugs and those taking antipsychotics at high dose for long periods. There is little evidence of an association with route of administration. More data are required to clarify to what extent people with mental health difficulties who die suddenly have pre-existing cardiac disease.
Ensuring the community cares: assessment and evaluation of social care needs in long-term mental illness
Authors: Davenport Sarah
Published: January 2006

Clinicians have been divided in their views on whether systematic needs assessment leads to an improvement in the outcome of care for people with chronic mental illness. Policy makers assume that assessment and evaluation will improve the clinical and cost-effectiveness of mental health services. Many of these assumptions are already embedded within mental health policy and practice. A decade of research has not resolved this tension. However, clinicians need to know about the options available to guide systematic assessment and evaluation of care. They can then make informed decisions about their use to promote effective care planning or as a tool to direct socially inclusive service development.
Come the revolution
Authors: Palmer Bob
Published: January 2006

Over the past decade there have been few advances and no real breakthroughs in the treatment and management of anorexia nervosa. There has perhaps been a consolidation of opinion and practice. A clinical guideline for eating disorders published under the auspices of the National Institute for Clinical Excellence (NICE) has summarised our present ideas of good practice as well as highlighting the lack of good evidence on which to base this.
Age‐Related Changes in Prefrontal White Matter Measured by Diffusion Tensor Imaging
Authors: SALAT D H , TUCH D S , HEVELONE N D , FISCHL B , CORKIN S , ROSAS H D , DALE A M
Published: January 2006

Age‐related degeneration of brain white matter (WM) has received a great deal of attention, with recent studies demonstrating that such changes are correlated with cognitive decline and increased risk for the development of age‐related neurodegenerative disease. Past studies have used magnetic resonance imaging (MRI) to measure the volume of normal and abnormal tissue signal as an index of tissue pathology. More recently, diffusion tensor MRI (DTI) has been employed to obtain regional measures of tissue microstructure, such as fractional anisotropy (FA), providing better spatial resolution and potentially more sensitive metrics of tissue damage than traditional volumetric measures. We used DTI to examine the regional basis of age‐related alterations in prefrontal WM. As expected from prior volumetric and DTI studies, prefrontal FA was reduced in older adults (OA) compared to young adults (YA). Although WM volume has been reported to be relatively preserved until late aging, FA was significantly reduced by middle age. Much of prefrontal WM showed reduced FA with increasing age. Ventromedial and deep prefrontal regions showed a somewhat greater reduction compared to other prefrontal areas. Prefrontal WM anisotropy correlated with prefrontal WM volume, but the correlation was significant only when the analysis was limited to participants over age 40. This evidence of widespread and regionally accelerated alterations in prefrontal WM with aging illustrates FA's potential as a microstructural index of volumetric measures.
Occipital‐Callosal Pathways in Children: Validation and Atlas Development
Authors: DOUGHERTY ROBERT F. , BEN‐SHACHAR MICHAL , DEUTSCH GAYLE , POTANINA POLINA , BAMMER ROLAND , WANDELL BRIAN A.
Published: January 2006

Diffusion tensor imaging and fiber tracking were used to measure fiber bundles connecting the two occipital lobes in 53 children of 7‐12 years of age. Independent fiber bundle estimates originating from the two hemispheres converge onto the lower half of the splenium. This observation validates the basic methodology and suggests that most occipital‐callosal fibers connect the two occipital lobes. Within the splenium, fiber bundles are organized in a regular pattern with respect to their cortical projection zones. Visual cortex dorsal to calcarine projects through a large band that fills much of the inferior half of the splenium, while cortex ventral to calcarine sends projections through a band at the anterior inferior edge of the splenium. Pathways projecting to the occipital pole and lateral‐occipital regions overlap the dorsal and ventral groups slightly anterior to the center of the splenium. To visualize these pathways in a typical brain, we combined the data into an atlas. The estimated occipital‐callosal fiber paths from the atlas form the walls of the occipital horn of the lateral ventricle, with dorsal paths forming the medial wall and the ventral paths bifurcating into a medial tract to form the inferior‐medial wall and a superior tract that joins the lateral‐occipital paths to form the superior wall of the ventricle. The properties of these fiber bundles match those of the hypothetical pathways described in the neurological literature on alexia.
The Application of DTI to Investigate White Matter Abnormalities in Schizophrenia
Authors: KUBICKI MAREK , WESTIN CARL‐FREDRIK , McCARLEY ROBERT W. , SHENTON MARTHA E.
Published: January 2006

Schizophrenia is a serious and disabling mental disorder that affects approximately 1% of the general population, with often devastating effects on the psychological and financial resources of the patient, family, and larger community. The etiology of schizophrenia is not known, although it likely involves several interacting biological and environmental factors that predispose an individual to schizophrenia. However, although the underlying pathology remains unknown, it has been believed that brain abnormalities would ultimately be linked to the etiology of schizophrenia. This theory was rekindled in the 1970s, when the first computer‐assisted tomography (CT) study showed enlarged lateral ventricles in schizophrenia. Since that time, there have been many improvements in MR acquisition and image processing, including the introduction of positron emission tomography (PET), followed by functional MR (fMRI), and diffusion tensor imaging (DTI). These advances have led to an appreciation of the critical role that brain abnormalities play in schizophrenia. While structural MRI has proven to be useful in investigating and detecting gray matter abnormalities in schizophrenia, the investigation of white matter has proven to be more challenging as white matter appears homogeneous on conventional MRI and the fibers connecting different brain regions cannot be appreciated. With the development of DTI, we are now able to investigate white matter abnormalities in schizophrenia.
Applications of Diffusion Tensor MR Imaging in Multiple Sclerosis
Authors: GE YULIN , LAW MENG , GROSSMAN ROBERT I.
Published: January 2006

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system that is the most common cause of nontraumatic disability in young adults in the United States. In recent years, magnetic resonance imaging (MRI) has been established as an important paraclinical tool in MS for the assessment of clinical diagnosis, natural history, and treatment effects. In MS studies, there are many advantages to having a sensitive and reliable in vivo method for investigating the specific pathological changes of white matter and its integrity during the disease process. As a consequence, in the past decade, the application of MRI to the study of MS has been explored from conventional MRI to new advanced quantitative techniques with greater pathological specificity and sensitivity. Diffusion tensor imaging (DTI) is one of the most promising techniques with regard to MS. It quantifies the amount of nonrandom water diffusion within tissues and provides unique in vivo information about the pathological processes that affect water diffusion as a result of brain microstructural damage. This review outlines the current state of the art and future direction of DTI and fiber tractography in the study of MS disease.
Quantitative Analysis of Diffusion Tensor Imaging Data in Serial Assessment of Krabbe Disease
Authors: PROVENZALE JAMES M. , ESCOLAR MARIA , KURTZBERG JOANNE
Published: January 2006

Krabbe disease is a rare autosomal recessive pediatric white matter (WM) disorder that is due to deficiency of a specific enzyme, β‐galactocerebrosidase. This report reviews our experience with use of diffusion tensor imaging (DTI) in serial assessment of WM changes in Krabbe disease following stem cell transplantation. DTI appears to be a sensitive means to monitor effects of stem cell transplantation on WM development in Krabbe disease. The group of early transplantation infants was clearly distinguishable from the group of late transplantation infants based on anisotropy measurements. Good correlation also was seen between neurodevelopmental scores and anisotropy measurements. The work described here in Krabbe disease may serve as a model for application of DTI to other therapies in various WM disorders such as multiple sclerosis and dysmyelinating disorders of childhood.
Knock‐down of the Cytoprotective Gene, Clusterin, to Enhance Hormone and Chemosensitivity in Prostate and Other Cancers
Authors: GLEAVE MARTIN , CHI KIM N.
Published: January 2006

Discovery and targeting of genes mediating treatment resistance may lead to development of novel therapies that delay progression of recurrent and refractory cancers. Clusterin is a stress‐associated cytoprotective chaperone expressed in many cancers that is upregulated in an adaptive cell survival manner by various apoptotic triggers and confers treatment resistance. Here, we review clusterin's functional role in regulating treatment‐induced apoptosis and the use of a second generation antisense oligonucleotide to inhibit clusterin expression to enhance the cytotoxic effects of hormone‐ and chemotherapy in prostate and other xenograft models, as well as in recent human trials.
Design and Development of Thermolytic DNA Oligonucleotide Prodrugs
Authors: GRAJKOWSKI ANDRZEJ , PEDRAS‐VASCONCELOS JOAO , AUSÍN CRISTINA , VERTHELYI DANIELA , BEAUCAGE SERGE L.
Published: January 2006

Deoxyribonucleoside phosphoramidites functionalized with the thermolytic 2‐(N‐formyl‐N‐methyl)aminoethyl group for phosphorus protection (1a‐d) have been prepared and employed in the solid‐phase synthesis of CpG ODN fma1555. Given that this modified oligonucleotide can be converted to the immunomodulatory CpG ODN 1555 under neutral conditions at 37°C, its biologic activity was demonstrated in vivo by studies showing that intraperitoneal administration of CpG ODN fma1555 in mice resulted in the activation of cytokine‐secreting splenocytes. Furthermore, administration of CpG ODN fma1555 to mice that were challenged intradermally in the ear with live L. major metacyclic promastigotes, reduced the severity of Leishmania skin lesions over time to an extent similar to that obtained with CpG ODN 1555. In another infectious model experiment, CpG ODN fma1555 protected newborn mice from death (65% survival) when administered 3 days before infection with the aggressive Tacaribe (TCRV) virus. A comparable immunoprotection was obtained by treatment of TCRV‐infected mice with CpG ODN 1555 administered on the same day of infection (45% survival). However, when TCRV‐infected mice were treated with CpG ODN fma1555 on the day of infection, they died as a consequence of the relatively slow conversion of the oligonucleotide prodrug to the bioactive CpG ODN 1555. Co‐administration of both CpG ODN 1555 and CpG ODN fma1555 to mice 3 days prior to TCRV infection or on the day of infection provided protection from death (45‐65% survival) and thus widened the immunoprotection window against TCRV‐infection.
Rationally Targeted, Conformationally Constrained, Oxetane‐Modified Oligonucleotides Demonstrate Efficient Gene‐Silencing Activity in a Cellular System
Authors: OPALINSKA J B , GEWIRTZ A M
Published: January 2006

Antisense oligodeoxynucleotides (AS ODN) have been employed as gene‐silencing agents in the laboratory and, in the clinic. The in vivo use of these molecules has been facilitated by chemical modifications to the DNA backbone which augment their nuclease stability. Attempts to further improve the efficacy of AS ODN have largely focused on 2′ alterations of the ribose sugar that make the molecules more RNA like in structure. This increases the Tm of formed DNA/RNA hybrids but simultaneously prevents binding of RNaseH which is important for ODN effectiveness. Herein, we demonstrate the use of AS ODN containing nucleosides with a novel oxetane (OXE) modification [oxetane, 1‐(1′, 3′‐O‐anhydro‐β‐D‐psicofuranosyl nucleosides)] which augments Tm, enhances nuclease stability, and is permissive of RNaseH activation. We also illustrate herein the value of rational targeting of OXE modified, and by analogy, AS ODN of any chemical modification.
Tumor Reversion: Protein Kinase A Isozyme Switching
Authors: CHO‐CHUNG YOON S. , NESTEROVA MARIA V.
Published: January 2006

The regulatory subunit of cAMP‐dependent protein kinase (PKA) exists in the isoforms RI and RII, which distinguish PKA isozymes type I (PKA‐I) and type II (PKA‐II). Evidence obtained from different experimental approaches—such as site‐selective cAMP analogs, antisense oligonucleotides, transcription factor decoys, cDNA microarrays, and gene transfer—has shown that PKA‐I and ‐II are expressed in a balance of cell growth and differentiation. Loss of this balance may underlie cancer genesis and progression. DNA microarrays demonstrate that antisense suppression of the RIα, which upregulates RIIβ, downregulates a wide range of genes involved in cell proliferation and transformation while upregulating cell differentiation and reverse transformation genes in PC3M prostate tumors that undergo regression. Conversely, the vector‐mediated overexpression of RIIβ, as opposed to those of RIα and Cα, exhibits induction of differentiation genes along with suppression of cell proliferation and transformation genes leading to reversion of tumor phenotype. Thus, switching of PKA isozyme can cause tumor cells to undergo phenotypic reversion of the malignancy.
Breaking Tolerance to Tumors with Dendritic Cell‐Based Immunotherapy
Authors: MENDE INES , ENGLEMAN EDGAR G.
Published: January 2006

Dendritic cells (DC) are the most potent antigen‐presenting cells known, capable of priming both naïve CD4 and CD8 T lymphocytes. In their immature state DC are especially efficient at ingesting dying cells and processing their antigens while in their mature state DC express high levels of both MHC class I and II antigens as well as a variety of costimulatory molecules needed to induce a primary T cell response. In addition to stimulating adaptive T cell responses, DC can stimulate NK cells and B cells. Their dual role in innate and adaptive immunity led us to explore their potential utility in tumor immunotherapy. The results of clinical trials in which autologous DC loaded with tumor antigen are administered to tumor‐bearing patients have been promising, but overall immunologic potency and clinical efficacy have been unsatisfactory. It has become clear that more potent and more efficient DC based immunotherapies are needed, preferably based on in vivo targeting of DC rather than in vitro manipulation followed by systemic administration of the cells. Recent studies in animal models suggest that DC can be loaded with antigen and activated in vivo in a manner that results in potent antitumor immunity. Two approaches to DC targeting are described in this review, both of which have been shown to overcome immune tolerance to tumors and induce dramatic tumor regression.
Development of Resistance to RNAi in Mammalian Cells
Authors: ZHENG ZHI‐MING , TANG SHUANG , TAO MINGFANG
Published: January 2006

The discovery of RNA interference (RNAi) in C. elegans and in plants has revolutionized current approaches to biology and medicine. RNAi silences genes in a sequence‐specific manner through the actions of small pieces of double‐stranded RNAs (siRNAs and miRNAs). RNAi has been found as a widespread natural phenomenon in eukaryotic cells and is also being used as a powerful experimental tool to explore gene function. Most importantly, it has many potential therapeutic applications. Viral gene‐specific siRNAs are theoretically very promising antiviral inhibitors and have been examined in a broad range of medically important viruses. However, many RNA viruses escape RNAi‐mediated suppression by counteracting the RNAi machinery through mutation of the targeted region, by encoding viral suppressors, or both. DNA viruses also counteract the RNAi machinery, preferentially using viral suppressors. Cellular factors may also contribute to RNAi resistance; ADAR1 was the first cellular factor found to be responsible for editing‐mediated RNAi resistance. Because siRNAs can be used as potent small‐molecule inhibitors of any cellular gene, the best way for a cell to maintain expression of essential genes for its long‐term survival is to develop a program to resist the detrimental effects of RNAi.
Targeted Genome Modification via Triple Helix Formation
Authors: KALISH JENNIFER M. , GLAZER PETER M.
Published: January 2006

Triplex‐forming oligonucleotides (TFOs) that can bind to duplex DNA in a sequence‐specific manner are potential tools to achieve targeted gene modification. Initial studies demonstrated the ability of TFOs to deliver mutagenic agents in a DNA site‐specific manner. It has also been found that TFOs can induce gene modification in chromosomal DNA via the effect of the triple helix itself. Gene modification with TFOs includes induced recombination between a DNA target and a donor DNA molecule, a process that allows a TFO to exert an effect at a distance from the third‐strand binding site. Ongoing efforts to develop chemical modifications on the third strand have increased the number of target sites possible for gene correction and new techniques for TFO delivery are beginning to enhance the biologic effectiveness of these reagents.
“Promoter Array” Studies Identify Cohorts of Genes Directly Regulated by Methylation, Copy Number Change, or Transcription Factor Binding in Human Cancer Cells
Authors: WANG YIPENG , HAYAKAWA JUN , LONG FRED , YU QIUJU , CHO ANN H. , RONDEAU GAELLE , WELSH JOHN , MITTAL SHALU , DE BELLE IAN , ADAMSON EILEEN , McCLELLAND MICHAEL , MERCOLA DAN
Published: January 2006

DNA microarrays of promoter sequences have been developed in order to identify the profile of genes bound and activated by DNA regulatory proteins such as the transcription factors c‐Jun and ATF2 as well as DNA‐modifying methylases. The arrays contain 3083 unique human promoter sequences from +500 to −1000 nts from the transcription start site. Cisplatin‐induced DNA damage rapidly leads to specific activation of the Jun kinase pathway leading to increased phosphorylation of c‐Jun and ATF2‐DNA complexes at hundreds of sites within 3 hours. Using three statistical criteria, approximately 269 most commonly phosphorylated c‐Jun/ATF2‐DNA complexes were identified and representative cases were verified by qPCR measurement of ChIP‐captured DNA. Expression was correlated at the mRNA and protein levels. The largest functional cohort was 24 genes of known DNA repair function, most of which exhibited increased protein expression indicated coordinate gene regulation. In addition, cell lines of prostate cancer exhibit stable methylation or copy number changes that reflect the alterations of the corresponding primary tumors. 504 (18.5%) promoters showed differential hybridization between immortalized control prostate epithelial and cancer cell lines. Among candidate hypermethylated genes in cancer‐derived lines, eight had previously been observed in prostate cancer, and 13 were previously determined methylation targets in other cancers. The vast majority of genes that appear to be both differentially methylated and differentially regulated between prostate epithelial and cancer cell lines are novel methylation targets, including PAK6, RAD50, TLX3, PIR51, MAP2K5, INSR, FBN1, GG2‐1, representing a rich new source of candidate genes to study the role of DNA methylation in prostate tumors. Earlier studies using prototype promoter arrays examine approximately 7% of the proximal regulatory sequences while the current gene regulatory events surveyed here occur on a large scale and may rapidly effect the coordinated expression of a large number of genes.
Application of Expression Genomics for Predicting Treatment Response in Cancer
Authors: CHIN KHEW‐VOON , ALABANZA LEAH , FUJII KAZUYUKI , KUDOH KAZUYA , KITA TSUNEKAZU , KIKUCHI YOSHIHIRO , SELVANAYAGAM ZACHARIAH E. , WONG YICK FU , LIN YONG , SHIH WEI CHUNG
Published: January 2006

During tumor progression, multiple genetic changes in the genome vastly alter the transcriptomes of cancers. Some of these changes, including the mutations of various growth regulatory genes as well as alterations in the transcription of a large number of genes, may lead to resistance to treatment. Therefore, capturing such genomic information of the tumors would enable a physician to decide on the course of treatment options clinically available. Currently, it is still not feasible to identify all the genetic mutations that have occurred in a patient's cancer genome. However, the advent of DNA microarray coupled with the completion of the human genome sequence and the identification of all its genes, have made possible genome‐wide gene expression profiling of the cancer genome. In this review, we will focus on the application of expression genomics for identifying signature gene expression profiles in primary cancers to predict response to either radio‐ or chemotherapy. We envision that transcription profiling of the cancer genomes ultimately will not only reveal how altered gene expression results in resistance to treatment, but also be exploited for predicting and personalizing cancer therapy.
Application of XIAP Antisense to Cancer and Other Proliferative Disorders: Development of AEG35156/ GEM®640
Authors: LACASSE ERIC C. , KANDIMALLA EKAMBAR R. , WINOCOUR PETER , SULLIVAN TIM , AGRAWAL SUDHIR , GILLARD JOHN W. , DURKIN JON
Published: January 2006

Targeting apoptosis control provides a novel therapeutic approach to the treatment of cancer and other proliferative disorders. We summarize the evidence for apoptosis deregulation in cancer and describe the pivotal role of XIAP, the X‐linked Inhibitor‐of‐APoptosis. XIAP is the predominant inhibitor of caspases 3, 7 and 9 in cells, which suppresses the programmed cell death effector capability of these proteases. Evidence is presented validating XIAP as a cancer target. The inhibition or downregulation of XIAP in cancer cells lowers the apoptotic threshold, thereby inducing cell death and/or enhancing the cytotoxic action of chemotherapeutic agents. We describe the development of AEG35156 (also named GEM®640), a second generation antisense compound targeting XIAP, from concept to in vivo preclinical proof‐of‐principle studies, through formal toxicology, and to a phase 1 clinical trial in cancer patients.
Zebularine: A Unique Molecule for an Epigenetically Based Strategy in Cancer Chemotherapy
Authors: MARQUEZ VICTOR E. , KELLEY JAMES A. , AGBARIA RIAD , BEN‐KASUS TISIPI , CHENG JONATHAN C. , YOO CHRISTINE B. , JONES PETER A.
Published: January 2006

1‐(β‐d‐ribofuranosyl)‐1,2‐dihydropyrimidin‐2‐one (zebularine) corresponds structurally to cytidine minus the exocyclic 4‐amino group. The increased electrophilic character of its simple aglycon endows the molecule with unique biologic properties as a potent inhibitor of both cytidine deaminase and DNA cytosine methyltransferase. The latter activity makes zebularine a promising antitumor agent that is hydrolytically stable, preferentially targets cancer cells, and shows activity both in vitro and in experimental animals, even after oral administration.