Neuronal-type-specific epigenome editing to decrease SNCA expression: Implications for precision medicine in synucleinopathies

Overexpression of SNCA has been implicated in the pathogenesis of synucleinopathies, particularly Parkinson's disease (PD) and dementia with Lewy bodies (DLB). While PD and DLB share some clinical and pathological similarities, each disease presents distinct characteristics, including the primary affected brain region and neuronal type. We aimed to develop neuronal-type-specific SNCA-targeted epigenome therapies for synucleinopathies. The system is based on an all-in-one lentiviral vector comprised of CRISPR-dSaCas9 and guide RNA (gRNA) targeted at SNCA intron 1 fused with a synthetic repressor molecule of Krüppel-associated box (KRAB)/ methyl CpG binding protein 2 (MeCp2) transcription repression domain (TRD). To achieve neuronal-type specificity for dopaminergic and cholinergic neurons, the system was driven by tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) promoters, respectively. Delivering the system into human induced pluripotent stem cell (hiPSC)-derived dopaminergic and cholinergic neurons from a patient with the SNCA triplication resulted in efficient and neuronal-type-specific downregulation of SNCA-mRNA and protein. Furthermore, the reduction in SNCA levels by the gRNA-dSaCas9-repressor system rescued disease-related cellular phenotypes including Ser129-phophorylated α-synuclein, neuronal viability, and mitochondrial dysfunction. We established a novel neuronal-type-specific SNCA-targeted epigenome therapy and provided in vitro proof of concept using human-based disease models. Our results support the therapeutic potential of our system for PD and DLB and provide the foundation for further preclinical studies in animal models toward investigational new drug (IND) enablement and clinical trials.

Therapeutic modulation of gene expression in the disease state: Treatment strategies and approaches for the development of next-generation of the epigenetic drugs

Epigenetic dysregulation is an important determinant of many pathological conditions and diseases. Designer molecules that can specifically target endogenous DNA sequences provide a means to therapeutically modulate gene function. The prokaryote-derived CRISPR/Cas editing systems have transformed our ability to manipulate the expression program of genes through specific DNA and RNA targeting in living cells and tissues. The simplicity, utility, and robustness of this technology have revolutionized epigenome editing for research and translational medicine. Initial success has inspired efforts to discover new systems for targeting and manipulating nucleic acids on the epigenetic level. The evolution of nuclease-inactive and RNA-targeting Cas proteins fused to a plethora of effector proteins to regulate gene expression, epigenetic modifications and chromatin interactions opened up an unprecedented level of possibilities for the development of “next-generation” gene therapy therapeutics. The rational design and construction of different types of designer molecules paired with viral-mediated gene-to-cell transfers, specifically using lentiviral vectors (LVs) and adeno-associated vectors (AAVs) are reviewed in this paper. Furthermore, we explore and discuss the potential of these molecules as therapeutic modulators of endogenous gene function, focusing on modulation by stable gene modification and by regulation of gene transcription. Notwithstanding the speedy progress of CRISPR/Cas-based gene therapy products, multiple challenges outlined by undesirable off-target effects, oncogenicity and other virus-induced toxicities could derail the successful translation of these new modalities. Here, we review how CRISPR/Cas—based gene therapy is translated from research-grade technological system to therapeutic modality, paying particular attention to the therapeutic flow from engineering sophisticated genome and epigenome-editing transgenes to delivery vehicles throughout efficient and safe manufacturing and administration of the gene therapy regimens. In addition, the potential solutions to some of the obstacles facing successful CRISPR/Cas utility in the clinical research are discussed in this review. We believe, that circumventing these challenges will be essential for advancing CRISPR/Cas-based tools towards clinical use in gene and cell therapies.

P-285 An analysis of automated morphometric measurements finds that a combination of a large blastocyst size and a short tB-tSB time interval doubles the implantation rate

Study question

Are automated blastocyst morphometric measurements combined with morphokinetic pattern associated with implantation rate?

Summary answer

Automated blastocyst morphometric measurements with morphokinetic pattern demonstrated that a larger blastocyst size and a shorter time interval tB-tSB are associated with higher implantation potential.

What is known already

Optimization of embryo selection is important for increasing implantation potential. Transfer of a high-quality blastocyst based on conventional morphological parameters has been shown to improve IVF clinical outcome. Novel parameters of blastocyst quality, including morphokinetics from time-lapse monitoring and manual analysis of morphometric parameters, have demonstrated promising results regarding implantation potential. However, manual measurement of morphometric parameters is a time-consuming task and is subjected to intra- and inter-observer variations. The introduction of automated morphometric measurements would remove subjective blastocyst analysis and further improve implantation rates.

Study design, size, duration

A nested retrospective case control analysis of 608 day-5 transferred blastocysts was conducted and included women who underwent IVF treatment in three public IVF units between 2014 and 2017.

Participants/materials, setting, methods

Automated morphometric blastocyst analysis was measured at the mean time of tEB-tPNf (85.82 h) by training a pixel-wise segmentation model (MaskRCNN) on time-lapse videos. Morphometric blastocyst parameters included the following: blastocyst size (μm), inner cell mass (ICM) size (μm), ICM to blastocyst size ratio, and ICM shape. Annotation variables included all the time intervals (hours) from time of pronuclei fading (tPNf) to the expanded blastocyst (tEB).

Main results and the role of chance

The mean blastocyst size for implanted embryos was significantly larger compared to non-implanted embryos (152.10 ±19.22μm vs 144.25±18.52μm, respectively, p < 0.001), while the mean interval times of tSB-tPNf, tB-tPNf, tEB-tPNf, tB-tSB, and tEB-tSB were significantly shorter (tSB-tPNf: 72.10±5.60h vs 73.30±5.80h, respectively, p = 0.016; tB-tPNf: 80.08±5.96h vs 82.54±5.92h, respectively, p < 0.001; tEB-tPNf: 84.95±5.43h vs 86.58±4.93h, respectively, p = 0.001; tB-tSB: 8.21±2.90h vs 9.49±3.62h, respectively, p < 0.001; and tEB-tSB: 13.50±3.00h vs 14.58±3.75h, respectively, p = 0.001). In a multivariable logistic model that measured the independent effect of ICM size, blastocyst size, tB-tSB, and woman age on implantation potential, blastocyst size was found to be positively associated with implantation potential (OR = 1.017, 95% CI 1.006-1.027, p = 0.002) while tB-tSB and woman age were found to be negatively associated (OR = 0.918, 95% CI 0.861-0.980, p = 0.010 and OR = 0.903, 95% CI 0.874-0.932, p < 0.001, respectively). Blastocyst size larger than the mean and a tB-tSB interval shorter than the mean had a 2.028 greater chance of implantation compared to blastocysts that did not meet these criteria (OR = 2.028, 95% CI 1.420-2.894, p < 0.001). In a multivariable logistic model adjusted for woman age, the chance for implantation among blastocysts meeting the aforementioned criteria was 1.7 greater (adjusted OR 1.714, 95% CI 1.182-2.485, p = 0.005). The AUC value for implantation prediction was 0.69 (p < 0.01).

Limitations, reasons for caution

The study's limitations include its retrospective nature and the absence of some patient characteristics.

Wider implications of the findings

A blastocyst selection based on the combination of automated blastocyst size measurements and manual tB-tSB time interval may double the implantation rate. The inclusion of automated morphometric measurements to the blastocyst selection algorithm may reduce intra- and inter-observer variations and should be incorporated into models for implantation prediction.

Trial registration number

0006-20-HMO

Cell-Type Specific Changes in DNA Methylation of SNCA Intron 1 in Synucleinopathy Brains

Parkinson's disease (PD) and dementia with Lewy body (DLB) are the most common synucleinopathies. SNCA gene is a major genetic risk factor for these diseases group, and dysregulation of its expression has been implicated in the genetic etiologies of several synucleinopathies. DNA methylation at CpG island (CGI) within SNCA intron 1 has been suggested as a regulatory mechanism of SNCA expression, and changes in methylation levels at this region were associated with PD and DLB. However, the role of DNA methylation in the regulation of SNCA expression in a cell-type specific manner and its contribution to the pathogenesis of PD and DLB remain poorly understood, and the data are conflicting. Here, we employed a bisulfite pyrosequencing technique to profile the DNA methylation across SNCA intron 1 CGI in PD and DLB compared to age- and sex-matched normal control subjects. We analyzed homogenates of bulk post-mortem frozen frontal cortex samples and a subset of neuronal and glia nuclei sorted by the fluorescence-activated nuclei sorting (FANS) method. Bulk brain tissues showed no significant difference in the overall DNA methylation across SNCA intron 1 CGI region between the neuropathological groups. Sorted neuronal nuclei from PD frontal cortex showed significant lower levels of DNA methylation at this region compared to normal controls, but no differences between DLB and control, while sorted glia nuclei exhibited trends of decreased overall DNA methylation in DLB only. In conclusion, our data suggested disease-dependent cell-type specific differential DNA methylation within SNCA intron 1 CGI. These changes may affect SNCA dysregulation that presumably mediates disease-specific risk. Our results can be translated into the development of the SNCA intron 1 CGI region as an attractive therapeutics target for gene therapy in patients who suffer from synucleinopathies due to SNCA dysregulation.

[Pharmacological Thromboprophylaxis in Acutely Ill Hospitalized Medical Patients]

Venous thromboembolic events (VTE) occur in approximately 50% of cases during or following hospitalization; VTE are a major cause of morbidity and mortality. Thromboprophylaxis for 6 to 14 days with heparins or fondaparinux has been demonstrated to be effective in VTE prevention in patients hospitalized for acute medical illnesses and reduced mobility. Nevertheless, the level of recommendation has been gradually downgraded as the benefit has been mainly demonstrated on the basis of systematic imaging diagnosed events. Direct oral anticoagulants have been assessed only as an extended prophylaxis, and are currently not recommended in medical thromboprophylaxis. Assessing the risk of VTE and bleeding in medical patients is complex. VTE and bleeding risk assessment scores were constructed but have not been validated. In order to improve the adequacy of prescriptions for thromboprophylaxis, the impact of different interventions has been the subject of several studies but these yielded varying results. The aim of this review is to analyze the indications for thromboprophylaxis in a medical setting with the latest available data.

The Path to Progress Preclinical Studies of Age-Related Neurodegenerative Diseases: A Perspective on Rodent and hiPSC-Derived Models

Alzheimer's disease (AD) and Parkinson's disease (PD) are the two most prevalent age-related neurodegenerative diseases, and currently no effective clinical treatments exist for either, despite decades of clinical trials. The failure to translate preclinical findings into effective treatments is indicative of a problem in the current evaluation pipeline for potential therapeutics. At present, there are no useful animal models for AD and PD research that reflect the entire biology of the diseases, specifically, the more common non-Mendelian forms. Whereas the field continues to seek suitable rodent models for investigating potential therapeutics for these diseases, rodent models have still been used primarily for preclinical studies. Here, we advocate for a paradigm shift toward the application of human-induced pluripotent stem cell (hiPSC)-derived systems for PD and AD modeling and the development of improved human-based models in a dish for drug discovery and preclinical assessment of therapeutic targets.

Adeno-Associated Virus-Mediated Gene Therapy in the Mashlool, Atp1a3Mashl/+, Mouse Model of Alternating Hemiplegia of Childhood

Alternating Hemiplegia of Childhood (AHC) is a devastating autosomal dominant disorder caused by ATP1A3 mutations, resulting in severe hemiplegia and dystonia spells, ataxia, debilitating disabilities, and premature death. Here, we determine the effects of delivering an extra copy of the normal gene in a mouse model carrying the most common mutation causing AHC in humans, the D801N mutation. We used an adeno-associated virus serotype 9 (AAV9) vector expressing the human ATP1A3 gene under the control of a human Synapsin promoter. We first demonstrated that intracerebroventricular (ICV) injection of this vector in wild-type mice on postnatal day 10 (P10) results in increases in ouabain-sensitive ATPase activity and in expression of reporter genes in targeted brain regions. We then tested this vector in mutant mice. Simultaneous intracisterna magna and bilateral ICV injections of this vector at P10 resulted, at P40, in reduction of inducible hemiplegia spells, improvement in balance beam test performance, and prolonged survival of treated mutant mice up to P70. Our study demonstrates, as a proof of concept, that gene therapy can induce favorable effects in a disease caused by a mutation of the gene of a protein that is, at the same time, an ATPase enzyme, a pump, and a signal transduction factor.

APOE: The New Frontier in the Development of a Therapeutic Target towards Precision Medicine in Late-Onset Alzheimer's

Alzheimer's disease (AD) has a critical unmet medical need. The consensus around the amyloid cascade hypothesis has been guiding pre-clinical and clinical research to focus mainly on targeting beta-amyloid for treating AD. Nevertheless, the vast majority of the clinical trials have repeatedly failed, prompting the urgent need to refocus on other targets and shifting the paradigm of AD drug development towards precision medicine. One such emerging target is apolipoprotein E (APOE), identified nearly 30 years ago as one of the strongest and most reproduceable genetic risk factor for late-onset Alzheimer's disease (LOAD). An exploration of APOE as a new therapeutic culprit has produced some very encouraging results, proving that the protein holds promise in the context of LOAD therapies. Here, we review the strategies to target APOE based on state-of-the-art technologies such as antisense oligonucleotides, monoclonal antibodies, and gene/base editing. We discuss the potential of these initiatives in advancing the development of novel precision medicine therapies to LOAD.

The mechanistic role of alpha-synuclein in the nucleus: impaired nuclear function caused by familial Parkinson's disease SNCA mutations

Alpha-synuclein SNCA has been implicated in the etiology of Parkinson's disease (PD); however, the normal function of alpha-synuclein protein and the pathway that mediates its pathogenic effect is yet to be discovered. We investigated the mechanistic role of SNCA in the nucleus utilizing isogenic human-induced pluripotent stem cells-derived neurons from PD patients with autosomal dominant mutations, A53T and SNCA-triplication, and their corresponding corrected lines by genome- and epigenome-editing. Comparisons of shape and integrity of the nuclear envelope and its resistance to stresses found that both mutations result in similar nuclear envelope perturbations that were reversed in the isogenic mutation-corrected cells. Further mechanistic studies showed that SNCA mutation has adverse effects on the nucleus by trapping Ras-related nuclear protein (RAN) and preventing it from transporting key nuclear proteins such as, DNMT3A, for maintaining normal nuclear function. For the first time, we proposed that α-syn interacts with RAN and normally functions in the nucleocytoplasmic transport while exerts its pathogenic effect by sequestering RAN. We suggest that defects in the nucleocytoplasmic transport components may be a general pathomechanistic driver of neurodegenerative diseases.

Good problems to have? Policy and societal implications of a disease-modifying therapy for presymptomatic late-onset Alzheimer's disease

In the United States alone, the prevalence of AD is expected to more than double from six million people in 2019 to nearly 14 million people in 2050. Meanwhile, the track record for developing treatments for AD has been marked by decades of failure. But recent progress in genetics, neuroscience and gene editing suggest that effective treatments could be on the horizon. The arrival of such treatments would have profound implications for the way we diagnose, triage, study, and allocate resources to Alzheimer's patients. Because the disease is not rare and because it strikes late in life, the development of therapies that are expensive and efficacious but less than cures, will pose particular challenges to healthcare infrastructure. We have a window of time during which we can begin to anticipate just, equitable and salutary ways to accommodate a disease-modifying therapy Alzheimer's disease. Here we consider the implications for caregivers, clinicians, researchers, and the US healthcare system of the availability of an expensive, presymptomatic treatment for a common late-onset neurodegenerative disease for which diagnosis can be difficult.

Viral-Mediated Gene Replacement Therapy in the Developing Central Nervous System: Current Status and Future Directions

The past few years have witnessed rapid developments in viral-mediated gene replacement therapy for pediatric central nervous system neurogenetic disorders. Here, we provide pediatric neurologists with an up-to-date, comprehensive overview of these developments and note emerging trends for future research. This review presents the different types of viral vectors used in viral-mediated gene replacement therapy; the fundamental properties of viral-mediated gene replacement therapy; the challenges associated with the use of this therapy in the central nervous system; the pathway for therapy development, from translational basic science studies to clinical trials; and an overview of the therapies that have reached clinical trials in patients. Current viral platforms under investigation include adenovirus vectors, adeno-associated viral vectors, lentiviral/retroviral vectors, and herpes simplex virus type 1 vectors. This review also presents an in-depth analysis of numerous studies that investigated these viral platforms in cultured cells and in transgenic animal models for pediatric neurogenetic disorders. Viral vectors have been applied to clinical trials for many different pediatric neurogenetic disorders, including Canavan disease, metachromatic leukodystrophy, neuronal ceroid lipofuscinosis, mucopolysaccharidosis III, spinal muscular atrophy, and aromatic l-amino acid decarboxylase deficiency. Of these diseases, only spinal muscular atrophy has a viral-mediated gene replacement therapy approved for marketing. Despite significant progress in therapy development, many challenges remain. Surmounting these challenges is critical to advancing the current status of viral-mediated gene replacement therapy for pediatric central nervous system neurogenetic disorders.

Gene-Editing Technologies Paired With Viral Vectors for Translational Research Into Neurodegenerative Diseases

Diseases of the central nervous system (CNS) have historically been among the most difficult to treat using conventional pharmacological approaches. This is due to a confluence of factors, including the limited regenerative capacity and overall complexity of the brain, problems associated with repeated drug administration, and difficulties delivering drugs across the blood-brain barrier (BBB). Viral-mediated gene transfer represents an attractive alternative for the delivery of therapeutic cargo to the nervous system. Crucially, it usually requires only a single injection, whether that be a gene replacement strategy for an inherited disorder or the delivery of a genome- or epigenome-modifying construct for treatment of CNS diseases and disorders. It is thus understandable that considerable effort has been put towards the development of improved vector systems for gene transfer into the CNS. Different viral vectors are of course tailored to their specific applications, but they generally should share several key properties. The ideal viral vector incorporates a high-packaging capacity, efficient gene transfer paired with robust and sustained expression, lack of oncogenicity, toxicity and pathogenicity, and scalable manufacturing for clinical applications. In this review, we will devote attention to viral vectors derived from human immunodeficiency virus type 1 (lentiviral vectors; LVs) and adeno-associated virus (AAVs). The high interest in these viral delivery systems vectors is due to: (i) robust delivery and long-lasting expression; (ii) efficient transduction into postmitotic cells, including the brain; (iii) low immunogenicity and toxicity; and (iv) compatibility with advanced manufacturing techniques. Here, we will outline basic aspects of LV and AAV biology, particularly focusing on approaches and techniques aiming to enhance viral safety. We will also allocate a significant portion of this review to the development and use of LVs and AAVs for delivery into the CNS, with a focus on the genome and epigenome-editing tools based on clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas 9) and the development of novel strategies for the treatment of neurodegenerative diseases (NDDs).

Lentiviral Vector Platform for the Efficient Delivery of Epigenome-editing Tools into Human Induced Pluripotent Stem Cell-derived Disease Models

The use of hiPSC-derived cells represents a valuable approach to study human neurodegenerative diseases. Here, we describe an optimized protocol for the differentiation of hiPSCs derived from a patient with the triplication of the alpha-synuclein gene (SNCA) locus into Parkinson's disease (PD)-relevant dopaminergic neuronal populations. Accumulating evidence has shown that high levels of SNCA are causative for the development of PD. Recognizing the unmet need to establish novel therapeutic approaches for PD, especially those targeting the regulation of SNCA expression, we recently developed a CRISPR/dCas9-DNA-methylation-based system to epigenetically modulate SNCA transcription by enriching methylation levels at the SNCA intron 1 regulatory region. To deliver the system, consisting of a dead (deactivated) version of Cas9 (dCas9) fused with the catalytic domain of the DNA methyltransferase enzyme 3A (DNMT3A), a lentiviral vector is used. This system is applied to cells with the triplication of the SNCA locus and reduces the SNCA-mRNA and protein levels by about 30% through the targeted DNA methylation of SNCA intron 1. The fine-tuned downregulation of the SNCA levels rescues disease-related cellular phenotypes. In the current protocol, we aim to describe a step-by-step procedure for differentiating hiPSCs into neural progenitor cells (NPCs) and the establishment and validation of pyrosequencing assays for the evaluation of the methylation profile in the SNCA intron 1. To outline in more detail the lentivirus-CRISPR/dCas9 system used in these experiments, this protocol describes how to produce, purify, and concentrate lentiviral vectors and to highlight their suitability for epigenome- and genome-editing applications using hiPSCs and NPCs. The protocol is easily adaptable and can be used to produce high titer lentiviruses for in vitro and in vivo applications.

Downregulation of SNCA Expression by Targeted Editing of DNA Methylation: A Potential Strategy for Precision Therapy in PD

Elevated levels of SNCA have been implicated in the pathogenesis of Parkinson's disease (PD), while normal physiological levels of SNCA are needed to maintain neuronal function. We ought to develop new therapeutic strategies targeting the regulation of SNCA expression. DNA methylation at SNCA intron 1 regulates SNCA transcription, and PD brains showed differential methylation levels compared to controls. Thus, DNA methylation at SNCA intron 1 is an attractive target for fine-tuned downregulation of SNCA levels. Here we developed a system, comprising an all-in-one lentiviral vector, for targeted DNA methylation editing within intron 1. The system is based on CRISPR-deactivated Cas9 (dCas9) fused with the catalytic domain of DNA-methyltransferase 3A (DNMT3A). Applying the system to human induced pluripotent stem cell (hiPSC)-derived dopaminergic neurons from a PD patient with the SNCA triplication resulted in fine downregulation of SNCA mRNA and protein mediated by targeted DNA methylation at intron 1. Furthermore, the reduction in SNCA levels by the guide RNA (gRNA)-dCas9-DMNT3A system rescued disease-related cellular phenotype characteristics of the SNCA triplication hiPSC-derived dopaminergic neurons, e.g., mitochondrial ROS production and cellular viability. We established that DNA hypermethylation at SNCA intron 1 allows an effective and sufficient tight downregulation of SNCA expression levels, suggesting the potential of this target sequence combined with the CRISPR-dCas9 technology as a novel epigenetic-based therapeutic approach for PD.

A Protocol for the Production of Integrase-deficient Lentiviral Vectors for CRISPR/Cas9-mediated Gene Knockout in Dividing Cells

Lentiviral vectors are an ideal choice for delivering gene-editing components to cells due to their capacity for stably transducing a broad range of cells and mediating high levels of gene expression. However, their ability to integrate into the host cell genome enhances the risk of insertional mutagenicity and thus raises safety concerns and limits their usage in clinical settings. Further, the persistent expression of gene-editing components delivered by these integration-competent lentiviral vectors (ICLVs) increases the probability of promiscuous gene targeting. As an alternative, a new generation of integrase-deficient lentiviral vectors (IDLVs) has been developed that addresses many of these concerns. Here the production protocol of a new and improved IDLV platform for CRISPR-mediated gene editing and list the steps involved in the purification and concentration of such vectors is described and their transduction and gene-editing efficiency using HEK-293T cells was demonstrated. This protocol is easily scalable and can be used to generate high titer IDLVs that are capable of transducing cells in vitro and in vivo. Moreover, this protocol can be easily adapted for the production of ICLVs.

Succination of Protein Disulfide Isomerase Links Mitochondrial Stress and Endoplasmic Reticulum Stress in the Adipocyte During Diabetes

AIMS

Protein succination by fumarate increases in the adipose tissue of diabetic mice and in adipocytes matured in high glucose as a result of glucotoxicity-driven mitochondrial stress. The endoplasmic reticulum (ER) oxidoreductase protein disulfide isomerase (PDI) is succinated in adipocytes that are matured in high glucose, and in this study we investigated whether succination would alter PDI oxidoreductase activity, directly linking mitochondrial stress and ER stress.

RESULTS

Protein succination and the ER stress marker C/EBP homologous protein (CHOP) were diminished after pharmaceutical targeting of mitochondrial stress with the chemical uncoupler niclosamide in adipocytes matured in high-glucose concentrations. PDI was succinated by fumarate on both CXXC-containing active sites, contributing to reduced enzymatic activity. Succinated PDI decreased reductase activity in adipocytes matured in high glucose, and in db/db epididymal adipose tissue, in association with increased levels of CHOP. PDI succination was increased in fumarase knockdown adipocytes, leading to reduced PDI oxidoreductase activity, increased CHOP levels, and pro-inflammatory cytokine secretion, confirming the specific role of elevated fumarate levels in contributing to ER stress. In addition, PDI succination and ER stress were decreased, and PDI reductase activity was restored when exposure to chronic high glucose was limited, highlighting the importance of calorie restriction in the improvement of adipocyte metabolic function.

INNOVATION

These experiments identify PDI succination as a novel biochemical mechanism linking altered mitochondrial metabolism to ER stress in the adipocyte during diabetes.

CONCLUSION

The current study demonstrates that early biochemical changes in mitochondrial metabolism have important implications for the development of adipocyte stress. Antioxid. Redox Signal. 27, 1281-1296.

Clinical applications involving CNS gene transfer

Diseases of the central nervous system (CNS) have traditionally been the most difficult to treat by traditional pharmacological methods, due mostly to the blood-brain barrier and the difficulties associated with repeated drug administration targeting the CNS. Viral vector gene transfer represents a way to permanently provide a therapeutic protein within the nervous system after a single administration, whether this be a gene replacement strategy for an inherited disorder or a disease-modifying protein for a disease such as Parkinson's. Gene therapy approaches for CNS disorders has evolved considerably over the last two decades. Although a breakthrough treatment has remained elusive, current strategies are now considerably safer and potentially much more effective. This chapter will explore the past, current, and future status of CNS gene therapy, focusing on clinical trials utilizing adeno-associated virus and lentiviral vectors.

Methods for gene transfer to the central nervous system

Gene transfer is an increasingly utilized approach for research and clinical applications involving the central nervous system (CNS). Vectors for gene transfer can be as simple as an unmodified plasmid, but more commonly involve complex modifications to viruses to make them suitable gene delivery vehicles. This chapter will explain how tools for CNS gene transfer have been derived from naturally occurring viruses. The current capabilities of plasmid, retroviral, adeno-associated virus, adenovirus, and herpes simplex virus vectors for CNS gene delivery will be described. These include both focal and global CNS gene transfer strategies, with short- or long-term gene expression. As is described in this chapter, an important aspect of any vector is the cis-acting regulatory elements incorporated into the vector genome that control when, where, and how the transgene is expressed.

Dominant-negative androgen receptor inhibition of intracrine androgen-dependent growth of castration-recurrent prostate cancer

Background

Prostate cancer (CaP) is the second leading cause of cancer death in American men. Androgen deprivation therapy is initially effective in CaP treatment, but CaP recurs despite castrate levels of circulating androgen. Continued expression of the androgen receptor (AR) and its ligands has been linked to castration-recurrent CaP growth.

Principal Finding

In this report, the ligand-dependent dominant-negative ARΔ142–337 (ARΔTR) was expressed in castration-recurrent CWR-R1 cell and tumor models to elucidate the role of AR signaling. Expression of ARΔTR decreased CWR-R1 tumor growth in the presence and absence of exogenous testosterone (T) and improved survival in the presence of exogenous T. There was evidence for negative selection of ARΔTR transgene in T-treated mice. Mass spectrometry revealed castration-recurrent CaP dihydrotestosterone (DHT) levels sufficient to activate AR and ARΔTR. In the absence of exogenous testosterone, CWR-R1-ARΔTR and control cells exhibited altered androgen profiles that implicated epithelial CaP cells as a source of intratumoral AR ligands.

Conclusion

The study provides in vivo evidence that activation of AR signaling by intratumoral AR ligands is required for castration-recurrent CaP growth and that epithelial CaP cells produce sufficient active androgens for CaP recurrence during androgen deprivation therapy. Targeting intracrine T and DHT synthesis should provide a mechanism to inhibit AR and growth of castration-recurrent CaP.

AAV exploits subcellular stress associated with inflammation, endoplasmic reticulum expansion, and misfolded proteins in models of cystic fibrosis

Barriers to infection act at multiple levels to prevent viruses, bacteria, and parasites from commandeering host cells for their own purposes. An intriguing hypothesis is that if a cell experiences stress, such as that elicited by inflammation, endoplasmic reticulum (ER) expansion, or misfolded proteins, then subcellular barriers will be less effective at preventing viral infection. Here we have used models of cystic fibrosis (CF) to test whether subcellular stress increases susceptibility to adeno-associated virus (AAV) infection. In human airway epithelium cultured at an air/liquid interface, physiological conditions of subcellular stress and ER expansion were mimicked using supernatant from mucopurulent material derived from CF lungs. Using this inflammatory stimulus to recapitulate stress found in diseased airways, we demonstrated that AAV infection was significantly enhanced. Since over 90% of CF cases are associated with a misfolded variant of Cystic Fibrosis Transmembrane Conductance Regulator (ΔF508-CFTR), we then explored whether the presence of misfolded proteins could independently increase susceptibility to AAV infection. In these models, AAV was an order of magnitude more efficient at transducing cells expressing ΔF508-CFTR than in cells expressing wild-type CFTR. Rescue of misfolded ΔF508-CFTR under low temperature conditions restored viral transduction efficiency to that demonstrated in controls, suggesting effects related to protein misfolding were responsible for increasing susceptibility to infection. By testing other CFTR mutants, G551D, D572N, and 1410X, we have shown this phenomenon is common to other misfolded proteins and not related to loss of CFTR activity. The presence of misfolded proteins did not affect cell surface attachment of virus or influence expression levels from promoter transgene cassettes in plasmid transfection studies, indicating exploitation occurs at the level of virion trafficking or processing. Thus, we surmised that factors enlisted to process misfolded proteins such as ΔF508-CFTR in the secretory pathway also act to restrict viral infection. In line with this hypothesis, we found that AAV trafficked to the microtubule organizing center and localized near Golgi/ER transport proteins. Moreover, AAV infection efficiency could be modulated with siRNA-mediated knockdown of proteins involved in processing ΔF508-CFTR or sorting retrograde cargo from the Golgi and ER (calnexin, KDEL-R, β-COP, and PSMB3). In summary, our data support a model where AAV exploits a compromised secretory system and, importantly, underscore the gravity with which a stressed subcellular environment, under internal or external insults, can impact infection efficiency.

Misfolded proteins have been associated with a variety of disorders such as cystic fibrosis, diabetes insipidus, alpha-antitrypsin deficiency, Parkinson's disease, and cancer. In this study, by using cellular models of events in cystic fibrosis lung disease we have revealed an effect of misfolded proteins on increasing susceptibility to infection with a parvovirus. Infection efficiency was an order of magnitude higher in cells expressing misfolded Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutant proteins than in cells expressing the correctly folded protein. During infection, virus capsids accumulated near cellular factors that normally process misfolded proteins and are involved in retrograde trafficking from the Golgi to endoplasmic reticulum. Furthermore, we have demonstrated that infection efficiency can be attenuated by restoring correct protein folding or augmented by siRNA-mediated knockdown of secretory pathway components. Taken together our results indicate that converging cellular systems operate to clear misfolded proteins and virus capsids from an infected cell. We raise the possibility that parvoviruses and perhaps other viruses exploit congested cellular secretory pathways during entry, and that viral infection could be a contributing factor in the progression of diseases associated with misfolded proteins.

Proteasome inhibitors enhance gene delivery by AAV virus vectors expressing large genomes in hemophilia mouse and dog models: a strategy for broad clinical application

Delivery of genes that are larger than the wild-type adeno-associated virus (AAV) 4,681 nucleotide genome is inefficient using AAV vectors. We previously demonstrated in vitro that concurrent proteasome inhibitor (PI) treatment improves transduction by AAV vectors encoding oversized transgenes. In this study, an AAV vector with a 5.6 kilobase (kb) factor VIII expression cassette was used to test the effect of an US Food and Drug Administration-approved PI (bortezomib) treatment concurrent with vector delivery in vivo. Intrahepatic vector delivery resulted in factor VIII expression that persisted for >1 year in hemophilia mice. Single-dose bortezomib given with AAV2 or AAV8 factor VIII vector enhanced expression on average ~600 and ~300%, respectively. Moreover, coadministration of AAV8.canineFVIII (1 × 10(13) vg/kg) and bortezomib in hemophilia A dogs (n = 4) resulted in normalization of the whole blood clotting time (WBCT) and 90% reduction in hemorrhages for >32 months compared to untreated hemophilia A dogs (n = 3) or dogs administered vector alone (n = 3). Demonstration of long-term phenotypic correction of hemophilia A dogs with combination adjuvant bortezomib and AAV vector expressing the oversized transgene establishes preclinical studies that support testing in humans and provides a working paradigm to facilitate a significant expansion of therapeutic targets for human gene therapy.

A large U3 deletion causes increased in vivo expression from a nonintegrating lentiviral vector

The feasibility of using nonintegrating lentiviral vectors has been demonstrated by recent studies showing their ability to maintain transgene expression both in vitro and in vivo. Furthermore, human immunodeficiency virus-1 (HIV-1) vectors packaged with a mutated integrase were able to correct retinal disease in a mouse model. Interestingly, these results differ from earlier studies in which first-generation nonintegrating lentiviral vectors yielded insignificant levels of transduction. However, to date, a rigorous characterization of transgene expression from the currently used self-inactivating (SIN) nonintegrating lentiviral vectors has not been published. In this study, we characterize transgene expression from SIN nonintegrating lentiviral vectors. Overall, we found that nonintegrating vectors express transgenes at a significantly lower level than their integrating counterparts. Expression from nonintegrating vectors was improved upon introducing a longer deletion in the vector's U3 region. A unique shuttle-vector assay indicated that the relative abundance of the different episomal forms was not altered by the longer U3 deletion. Interestingly, the longer U3 deletion did not enhance expression in the corpus callosum of the rat brain, suggesting that the extent of silencing of episomal transcription is influenced by tissue-specific factors. Finally, and for the first time, episomal expression in the mouse liver was potent and sustained.

The Prader-Willi/Angelman imprinted domain and its control center

The present review focuses on the recent advances towards understanding the mode of operation of the imprinting center (IC) within the Prader-Willi/Angelman syndromes (PWS/AS) domain. Special emphasis is put on the elucidation of the functional interaction between the two parts of the center, AS-IC and PWS-IC. The recent studies, on which the review is based, reveal cis-acting elements and trans-acting proteins that constitute the two parts of the IC and presumably provide the molecular mechanism for this interaction. AS-IC acquires the primary imprint during gametogenesis by establishing the maternal epigenotype. The unmethylated maternal allele of the AS-IC binds, very likely, a trans-acting factor that confers methylation on the PWS-IC maternal allele after fertilization. It is assumed that the PWS-IC paternal epigenotype, once established, spreads across the entire PWS/AS domain in the soma.

DNA methylation in epigenetic control of gene expression

Over three decades ago DNA methylation had been suggested to play a role in the regulation of gene expression. This chapter reviews the development of this field of research over the last three decades, from the time when this idea was proposed up until now when the molecular mechanisms involved in the effect of DNA methylation on gene expression are becoming common knowledge. The dynamic changes that the DNA methylation pattern undergoes during gametogenesis and embryo development have now been revealed. The three-way connection between DNA methylation, chromatin structure and gene expression has been recently clarified and the interrelationships between DNA methylation and histone modification are currently under investigation. DNA methylation is implicated in developmental processes such as X-chromosome inactivation, genomic imprinting and disease, including tumor development. This chapter discusses all these issues in depth.

Establishing the epigenetic status of the Prader-Willi/Angelman imprinting center in the gametes and embryo

The Prader-Willi/Angelman imprinted domain on human chromosome 15q11-q13 is regulated by an imprinting control center (IC) composed of a sequence around the SNRPN promoter (PWS-SRO) and a sequence located 35 kb upstream (AS-SRO). We have previously hypothesized that the primary imprint is established on AS-SRO, which then confers imprinting on PWS-SRO. Here we examine this hypothesis using a transgene that includes both AS-SRO and PWS-SRO sequences and carries out the entire imprinting process. The epigenetic features of this transgene resemble those previously observed on the endogenous locus, thus allowing analyses in the gametes and early embryo. We demonstrate that the primary imprint is in fact established in the gametes, creating a differentially methylated CpG cluster (DMR) on AS-SRO, presumably by an adjacent de novo signal (DNS). The DMR and DNS bind specific proteins: an allele-discrimination protein (ADP) and a de novo methylation protein, respectively. ADP, being a maternal protein, is involved in both the establishment of DMR in the gametes and in its maintenance through implantation when methylation of PWS-SRO on the maternal allele takes place. Importantly, while the AS-SRO is required in the gametes to confer methylation on PWS-SRO, it is dispensable later in development.

Expression and localization of components of the histone deacetylases multiprotein repressory complexes in the mouse preimplantation embryo

DNA methylation had been implicated in the assembly of multiprotein repressory complexes that affect chromatin architecture thereby rendering genes inactive. Proteins containing methyl binding domains (MBDs) are major components of these complexes. MBD3 is a component of the HDAC associated chromatin remodeling complex Mi2/NuRD. The addition of MBD2 to the Mi2/NuRD complex creates MeCP1, a complex that is known to inactivate methylated promoters. The undermethylated state of the mouse preimplantation embryo prompted us to investigate the known repressory complexes at this developmental stage. We found individual components of Mi2/NuRD: MBD3, Mi2, HDAC1 and HDAC2 to be expressed from a very early stage of embryo development and to localize in close proximity with each other and with constitutive heterochromatin by the blastula stage. Expression of MBD2, a component of MeCP1, starts in the blastula stage. Then it is also found to be in proximity with heterochromatin (based on DAPI staining) and with MBD3, Mi2 and HDAC1. In contrast, expression of MeCP2, an MBD containing component of a third repressory complex (MeCP2/Sin3A), is not seen in the preimplantation embryo. Our results suggest that both Mi2/NuRD and MeCP1 complexes are already present at the very early stages of embryo development, while a MeCP2 complex is added to the arsenal of repressory complexes post-implantation at a stage when DNA methylation takes place.

Control elements within the PWS/AS imprinting box and their function in the imprinting process

A cluster of imprinted genes on human chromosome 15q11-q13 (the PWS/AS domain) and its ortholog on mouse chromosome 7c is believed to be regulated by an imprinting control center. Although minideletions in this region in Angelman syndrome (AS) and Prader-Willi syndrome (PWS) patients revealed that two elements, shortest deletion regions of overlap in AS families and PWS families (AS-SRO and PWS-SRO), respectively, constitute the IC, the molecular mechanism that governs this regional control remains obscure. To understand how this imprinting center works, a mouse model was sought. The striking similarity between the human and mouse sequences allowed the generation of a minitransgene (AS-SMP) composed of AS-SRO and the Snrpn minimal promoter (SMP) the mouse ortholog of PWS-SRO. This minitransgene carries out, in a highly reliable and reproducible manner, all steps of the imprinting process. In an attempt to decipher the molecular mechanism of the imprinting process, we generated and tested for imprinting five minitransgenes based on AS-SMP, in which various parts of the 160 bp SMP were deleted. These experiments revealed a set of five cis elements that carry out the various steps of the imprinting process. This set includes: (i). two copies of a de novo methylation signal (DNS) that establish the maternal imprint during oogenesis; (ii). an allele discrimination signal that establishes the paternal imprint; and (iii). two elements that act together to maintain the paternal imprint. Two functionally redundant sets of the five elements were found on the respective endogenous mouse sequence explaining the previously published contradictory results of targeted deletion experiments. Together with the fact that all five elements bind specific proteins that are presumably the factors acting in trans in the imprinting process, our observations set the stage for a comprehensive study of the molecular mechanism involved in the control of the imprinting process.

Characterization of the human Snrpn minimal promoter and cis elements within it

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are caused by loss of gene function of the imprinted genes including Snrpn within a 2 Mb domain on chromosome 15q11-13. Based on microdeletions in PWS and AS patients, a 4.3 sequence around Snrpn promoter/exon 1, together with a 880 bp sequence upstream to Snrpn, are believed to encompass an imprinting control center for the entire 2 Mb domain. We have previously characterized the mouse Snrpn minimal promoter and a 7 bp element (SBE) within it, which is required for its activity. Here we describe the human Snrpn minimal promoter sequence, which is comprised of a 71 bp upstream sequence and 51 bp of exon 1. The SBE, which has been shown to be critical for mouse promoter activity, is also found in the human sequence and absolutely required for promoter activity. Methylation of this element, like in the mouse, prevents the binding of a protein factor and abolishes promoter activity. In addition, the 5' end of exon 1 must contain cis elements that support promoter activity. In contrast, the 3' end of exon 1 appears to repress promoter activity. This sequence specifically binds a protein factor which presumably exerts a repressory effect on the promoter. Methylation of this sequence prevents the binding of this protein.

Tryptase activates the mitogen-activated protein kinase/activator protein-1 pathway in human peripheral blood eosinophils, causing cytokine production and release

We have previously shown that mast cells enhance eosinophil survival and activation. In this study we further characterized mast cell activity toward eosinophils. Sonicate of both rat peritoneal mast cells and the human mast cell line 1 (HMC-1) induced a concentration-dependent IL-6 and IL-8 release from human peripheral blood eosinophils (ELISA). HMC-1-induced IL-8 release was significantly reduced by the tryptase inhibitors GW-45 and GW-58 (90 and 87%, respectively, at an optimal concentration) but not by anti-stem cell factor, anti-TNF-alpha, or anti-IFN-gamma neutralizing Abs or by the antihistamine drugs pyrilamine and cimetidine. In a manner similar to HMC-1, human recombinant tryptase induced the expression of mRNA for IL-8 (RT-PCR) and caused IL-8 release from the eosinophils. Addition of cycloheximide, actinomycin D, dexamethasone, PD 98059, curcumin, or SB 202190 completely inhibited the tryptase-induced IL-6 and IL-8 release. In contrast, cyclosporin A had no effect on tryptase-induced IL-8 release. Tryptase caused phosphorylation of extracellular signal-regulated kinases 1 and 2, c-Jun N-terminal kinases 1 and 2, and p38 (Western blot). Tryptase also induced the translocation of c-Jun from the cytosol to the nucleus (confocal microscopy) and enhanced AP-1 binding activity to the DNA (EMSA). Eosinophils were found to express proteinase-activated receptor 2 (FACS). When eosinophils were incubated with tryptase in the presence of anti-proteinase-activated receptor 2 antagonist Abs a significant decrease in the IL-6 and IL-8 release occurred. In summary, we have demonstrated that the preformed mast cell mediator tryptase induces cytokine production and release in human peripheral blood eosinophils by the mitogen-activated protein kinase/AP-1 pathway.

Validation of an Instrument Designed to Assess Medical Student Attitudes Toward Home Care

OBJECTIVES

To develop and validate an instrument to assess medical students' attitudes toward home care.

DESIGN

Survey administration before and following participation in a home care training program.

SETTING

Five medical schools in the United States.

PARTICIPANTS

326 third and fourth year medical students.

MEASUREMENTS

Factor analysis was performed on all posttests. Domains were tested for internal reliability (Chronbach's alpha). Interdomain correlation was tested. One-way analysis of variance (ANOVA) was used to determine whether the results for each domain differed among the five programs.

RESULTS

Using exploratory factor analysis, the original 20-item survey was revised to yield a 14-item survey consisting of four domains (general attitudes, home-based therapies, home care training, and time and reimbursement). Domain intra-item reliability ranged from 0.60 to 0.82. Interdomain correlations were found to be significant with the exception of one comparison (time and reimbursement and home care training). One-way ANOVA showed significant differences between the training programs for two of the four domains (home-based therapies and home care training). For a third domain, time and reimbursement, there was a trend toward differences across the schools (P = 0.06).

CONCLUSION

The instrument described in this paper is a reliable and valid instrument for assessing the impact of home care training on medical student attitudes across a series of important domains.

The mouse Snrpn minimal promoter and its human orthologue: activity and imprinting

BACKGROUND

Microdeletions in chromosome 15q13-15 of Prader-Willi (PWS) and Angelman Syndrome (AS) patients suggested that SNRPN promoter/exon 1, together with a short sequence located approximately 35 kb upstream, constitute an imprinting control centre that regulates the entire 2 Mb PWS/AS imprinted domain. We have recently shown that a minitransgene composed of the human upstream sequence and mouse Snrpn promoter/exon 1 harbours all the elements necessary for establishing and maintaining an imprinted state.

RESULTS

Here we describe, using transfection experiments, the Snrpn minimal promoter (SMP), being composed of the entire 76 bp exon 1 and 84 bp of upstream sequence. A 7 bp element (SBE) within SMP that, in its unmethylated state binds a specific protein, is absolutely required for promoter activity. The orthologous human sequence, in spite of the fact that it possesses an identical SBE, failed to display promoter activity in transfection experiments and failed to create a methylated state of the maternal allele. Transgenic experiments reveal that a mutation in SBE of the mouse sequence did not completely abolish methylation of the maternal allele, indicating that sequences outside SBE participate in this process. Replacement of human exon 1 with the mouse orthologue replenished promoter activity, but left the maternal allele in the transgenic experiment unmethylated. The reciprocal chimera, in which mouse exon 1 was replaced by the human orthologue resulted in loss of promoter activity and did not support differential methylation.

CONCLUSIONS

The observations made by in vitro and in vivo experiments suggest that several cis elements which are involved in Snrpn promoter activity and the imprinting process are present in the mouse promoter and absent in the human orthologous sequence.

[Economic aspects of using electron beam computerized tomography]

Electron beam computed tomography (EBCT) allows visualization and quantification of calcium in the coronary arteries. This has been demonstrated to correlate well with the overall plaque burden in the coronary arteries. EBCT is, therefore, well suited for the detection of early stages of coronary atherosclerosis. Especially in asymptomatic patients with several risk factors, staging coronary artery disease by coronary calcium, scanning may allow prognostic assessment and guide preventive and therapeutic interventions. To date, only scant data are available regarding the cost effectiveness and the economic impact of this imaging technique. In this manuscript we compare various methods for the diagnosis of coronary artery disease using a theoretical model and review the results of a prospective trial in our emergency room of coronary calcium scanning in patients with acute chest pain. Using Framingham data and prognostic data from long-term follow-up, we discuss the impact of coronary calcification scanning on primary preventive measures and its economical consequences. EBCT is a promising technique which has created a lot of attention due to its ease of application. It is currently undergoing critical appraisal in the medical literature. Further randomized prospective trials are needed (and underway, i.e., MESA, EDIC, CARDIA II) to better define its value and limitations in the clinical arena.

Gene therapy for myocardial angiogenesis: has it come of age?

Vasculogenesis and angiogenesis are the processes responsible for the development of the circulatory system during embryonic and adult life. Vasculogenesis occurs during embryogenesis while angiogenesis refers to blood vessel formation from any preexisting vasculature. Postnatal angiogenesis resumes during reproduction, wound healing, and ischemia. Excess blood vessel formation may contribute to initiating and maintaining many diseases such as chronic inflammatory disorders, tumor growth, restenosis, and atherosclerosis. In contrast. insufficient blood vessel formation is responsible for tissue ischemia, as in coronary artery disease. An increasing number of patients with advanced coronary artery disease remain symptomatic despite maximal interventional, surgical or medical treatment. Ideally, they would benefit most from additional arterial blood supply to ischemic areas of myocardium. Therapeutic angiogenesis, the ability to induce the growth of new blood vessels, is one of the most intriguing new frontiers in interventional cardiology for this growing patient group. Several approaches are currently undergoing intensive experimental investigations or have already entered early clinical trials involving either local angiogenic peptide administration or the transfection of angiogenic genes. Gene therapy for therapeutic myocardial angiogenesis is the most promising synthesis of two emerging technologies. In the following article, we will review the fundamental pathophysiological concepts of gene-based angiogenic therapy, the technical approaches and delivery systems, and the results of the first clinical trials. We will also discuss the controversies and unresolved issues of this new revascularization therapy.

Imaging Angiogenesis with Three-Dimensional Microscopic Computed Tomography

An increasing number of patients with advanced coronary artery disease remain symptomatic, despite maximal interventional or medical treatment. A high demand exists for alternative anti-anginal therapies and ways to improve survival. One of the most intriguing new approaches to increase blood flow to ischemic myocardium is therapeutic angiogenesis, the induction of new vessel growth. Current methods involve local angiogenic growth factor administration, transfection of genes expressing angiogenic proteins, or direct myocardial revascularization. These new therapeutics are undergoing intensive basic and clinical investigation.

Transmyocardial and percutaneous myocardial revascularization: current and future role in the treatment of coronary artery disease

Transmyocardial revascularization (TMR) is a new treatment modality under evaluation in patients with severely symptomatic, diffuse coronary artery disease, in whom the potential for medical or interventional management has been exhausted. Preliminary clinical trials show improved ischemic symptoms within the first 3 months in about 70% of TMR-treated patients. The original proposed mechanism of surgical or catheter-based TMR (percutaneous myocardial revascularization [PMR]) was that channels mediate direct blood flow between the left ventricular cavity and ischemic myocardium. However, several alternative explanations for the clinical success of TMR have recently been suggested, including improved perfusion by angiogenesis, an anesthetic effect by nerve destruction, and a potential placebo effect. This article reviews the clinical role of TMR/PMR, its possible pathophysiologic mechanisms, and its controversies. It provides an overview of the actual scientific and clinical status of TMR and details future directions.

The experimental animal models for assessing treatment of restenosis

Coronary restenosis after percutaneous interventions remains a major clinical problem. The assessment of therapies for the prevention of restenosis relies on the use of experimental models. This review describes the most frequently used animal models of coronary artery retenosis and the intraspecies differences among them, particularly in the extent and composition of the neointimal thickening. These differences in neointima formation should be considered in the interpretation of effective antiproliferative therapies before they are transferred into clinical trials.

Administrators' perceptions of nutrition services in home health care agencies

OBJECTIVE

Ascertain views of home care administrators regarding the need for nutrition services in home care, current status and gaps in dietitian services, and obstacles toward expansion.

DESIGN

Mailed survey.

SUBJECTS

Members of the National Association for Home Care residing in California, New York, Pennsylvania, Ohio, and Texas. Of the 1,992 questionnaires sent, 402 (20.1%) were completed and used for data analysis.

STATISTICAL ANALYSES PERFORMED

Descriptive statistics.

RESULTS

Respondents gave high importance to nutrition (6.2 on a 7-point scale), and 39.6% estimated that more than half of their patients were malnourished. Most respondents reported using dietitian services, either as consultants (45.5%) or full-time (5.8%) or part-time (11.9%) employees. Nurses (85.5%) were listed most often as providers of nutrition services; also listed were dietitians (70.6%), pharmacists (17.2%), and physicians (11.2%). More than half of the respondents did not have, but would like to have, a dietitian serve as a nutrition consultant, prepare nutrition care plans, and provide nutrition counseling for patients and caregivers. Primary deterrents noted were lack of reimbursement by third-party payers and lack of physician request. Dietitian services ranked as having the highest value were patient education and counseling, medical nutrition therapy for specific conditions, development of nutrition care plans, staff in-service training, and nutrition assessments. Most home care administrators expected dietitian hours, services, and staff to increase during the next 5 years.

APPLICATIONS

The growing home health care market is fertile ground for dietitians. To expand their role in home care, dietitians can position nutrition services as being vital to cost-effective, high-quality care; augment their skills in consultation, training, nutrition support, and outcomes research; strengthen collaborative ties with key home health care professionals; and advocate for Medicare coverage of medical nutrition therapy.

Phase-shifted surface-acoustic-wave resonator

The spatial distribution of the surface-acoustic-wave (SAW) intensity across a phase-shifted transducer-resonator is studied. A coupled-mode analysis of this structure shows that a highly confined mode can be excited in a pi/2 shifted resonator. Experimental verification of this conclusion was obtained in a LiNbO(3) pi/2 shifted resonator, in which the SAW intensity was measured. The concentration factor (the ratio of the maximum to average SAW intensity) can be ~10 for reasonably long resonators.