Biomedical subjects

Mark J Graham

Publications and source records attributed to Mark J Graham.

9 recordsLinked to original sources

PubMed2006

Liver-specific inhibition of acyl-coenzyme a:cholesterol acyltransferase 2 with antisense oligonucleotides limits atherosclerosis development in apolipoprotein B100-only low-density lipoprotein receptor-/- mice.

OBJECTIVE: The purpose of this study was to determine the effects of liver-specific inhibition of acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT2) on the development of hypercholesterolemia and atherosclerosis in mice. METHODS AND RESULTS: Apolipoprotein B100-only low-density lipoprotein (LDL) receptor-/- mice were given saline, a nontargeting control antisense oligonucleotide (ASO), or ASOs targeting ACAT2 biweekly for a period spanning 16 weeks. Mice treated with ACAT2 targeting ASOs had liver-specific reduction in ACAT2 mRNA, yet intestinal ACAT2 and cholesterol absorption was left undisturbed. ASO-mediated knockdown of ACAT2 resulted in reduction of total plasma cholesterol, increased levels of plasma triglyceride, and a shift in LDL cholesteryl ester (CE) fatty acid composition from mainly saturated and monounsaturated to polyunsaturated fatty acid enrichment. Furthermore, the liver-specific depletion of ACAT2 resulted in protection against diet-induced hypercholesterolemia and aortic CE deposition. This is the first demonstration that specific pharmacological inhibition of ACAT2, without affecting ACAT1, is atheroprotective. CONCLUSIONS: Hepatic ACAT2 plays a critical role in driving the production of atherogenic lipoproteins, and therapeutic interventions, such as the ACAT2-specific ASOs used here, which reduce acyltransferase 2 (ACAT2) function in the liver without affecting ACAT1, may provide clinical benefit for cardiovascular disease prevention.

Animals↗

PubMed2006

Modification of MyD88 mRNA splicing and inhibition of IL-1beta signaling in cell culture and in mice with a 2'-O-methoxyethyl-modified oligonucleotide.

A number of proinflammatory cytokines, including IL-1beta, signal through the adaptor protein MyD88. This signaling leads to phosphorylation of IL-1R-associated kinase-1 (IRAK-1) and, ultimately, activation of the NF-kappaB transcription factor. A splice variant of MyD88 (MyD88(S)), which lacks the ability to couple IRAK-1 to NF-kappaB, has been described. A chemically modified antisense oligonucleotide (ASO) that alters the splicing ratio of MyD88 to MyD88(S) in both cell culture and in animals has been identified. The ASO (ISIS 337846) binds to exon II donor sites in the MyD88 pre-mRNA. By manipulating levels of MyD88 splicing, proinflammatory signaling through the IL-1R has been shown to be diminished, both in cell culture and in mouse liver. To our knowledge, this represents the first example of modulation of RNA splicing of an endogenous gene target in animals after systemic ASO dosing and suggests that this mechanism may be useful as a novel modulator of inflammatory stimuli.

Adaptor Proteins, Signal Transducing↗

PubMed2006

A mouse monoclonal antibody specific for mouse apoB48 and apoB100 produced by immunizing "apoB39-only" mice with mouse apoB48.

We have generated and characterized a murine monoclonal antibody (mAb) that binds to both mouse apolipoprotein (apo) B48 and apoB100. We immunized "apoB39-only" mice (mice that synthesize a truncated form of apoB, apoB39, but no apoB48 or apoB100) with lipoproteins containing mouse apoB48 and then used splenocytes from the immunized mice to create hybridomas. We identified a hybridoma, 2G11, that secretes a mAb that binds to mouse apoB48 and apoB100 but not to apoB39. Antibody 2G11 also binds apoB48 and apoB100 from rats and hamsters but not from humans. The mAb recognizes mouse apoB equally in very low and low density lipoproteins and was used to quantify apoB in wild-type, apoE-deficient and low-density lipoprotein receptor-deficient mice and in mice treated with an antisense drug that lowers plasma apoB levels. The antibody will be an important reagent for studying mouse models of atherosclerosis. The study also underscores the utility of genetically modified mice for generating mouse mAbs against mouse proteins.

Animals↗

PubMed2005

An apolipoprotein B antisense oligonucleotide lowers LDL cholesterol in hyperlipidemic mice without causing hepatic steatosis.

High levels of plasma apolipoprotein B-100 (apoB-100), the principal apolipoprotein of LDL, are associated with cardiovascular disease. We hypothesized that suppression of apoB-100 mRNA by an antisense oligonucleotide (ASO) would reduce LDL cholesterol (LDL-C). Because most of the plasma apoB is made in the liver, and antisense drugs distribute to that organ, we tested the effects of a mouse-specific apoB-100 ASO in several mouse models of hyperlipidemia, including C57BL/6 mice fed a high-fat diet, Apoe-deficient mice, and Ldlr-deficient mice. The lead apoB-100 antisense compound, ISIS 147764, reduced apoB-100 mRNA levels in the liver and serum apoB-100 levels in a dose- and time-dependent manner. Consistent with those findings, total cholesterol and LDL-C decreased by 25-55% and 40-88%, respectively. Unlike small-molecule inhibitors of microsomal triglyceride transfer protein, ISIS 147764 did not produce hepatic or intestinal steatosis and did not affect dietary fat absorption or elevate plasma transaminase levels. These findings, as well as those derived from interim phase I data with a human apoB-100 antisense drug, suggest that antisense inhibition of this target may be a safe and effective approach for the treatment of humans with hyperlipidemia.

Animals↗

PubMed2004

Antisense oligonucleotide blockade of alpha 4 integrin prevents and reverses clinical symptoms in murine experimental autoimmune encephalomyelitis.

We investigated the use of an antisense oligonucleotide (ASO) specific for mRNA of the alpha chain (CD49d) of mouse VLA-4 to down-regulate VLA-4 expression and alter central nervous system (CNS) inflammation. ISIS 17044 potently and specifically reduced CD49d mRNA and protein in cell lines and in ex-vivo-treated primary mouse T cells. When administered prophylactically or therapeutically, ISIS 17044 reduced the incidence and severity of paralytic symptoms in a model of experimental autoimmune encephalomyelitis (EAE). This was accompanied by a significant decrease in the number of VLA-4+ cells, CD4(+) T cells, and macrophages present in spinal cord white matter of EAE mice. ISIS 17044 was found to accumulate in lymphoid tissue of mice, and oligonucleotide was also detected in endothelial cells and macrophage-like cells in the CNS, apparently due to disruption of the blood-brain barrier during EAE. These results demonstrate the potential utility of systemically administered antisense oligonucleotides for the treatment of central nervous system inflammation.

Animals↗

PubMed2004

2'-O-[2-[(N,N-dimethylamino)oxy]ethyl]-modified oligonucleotides inhibit expression of mRNA in vitro and in vivo.

Synthesis and antisense activity of oligonucleotides modified with 2'-O-[2-[(N,N-dimethylamino)oxy] ethyl] (2'-O-DMAOE) are described. The 2'-O-DMAOE-modified oligonucleotides showed superior metabolic stability in mice. The phosphorothioate oligonucleotide 'gapmers', with 2'-O-DMAOE- modified nucleoside residues at the ends and 2'-deoxy nucleosides residues in the central region, showed dose-dependent inhibition of mRNA expression in cell culture for two targets. 'Gapmer' oligonucleotides have one or two 2'-O-modified regions and a 2'-deoxyoligonucleotide phosphorothioate region that allows RNase H digestion of target mRNA. To determine the in vivo potency and efficacy, BalbC mice were treated with 2'-O-DMAOE gapmers and a dose-dependent reduction in the targeted C-raf mRNA expression was observed. Oligonucleotides with 2'-O-DMAOE modifications throughout the sequences reduced the intercellular adhesion molecule-1 (ICAM-1) protein expression very efficiently in HUVEC cells with an IC(50) of 1.8 nM. The inhibition of ICAM-1 protein expression by these uniformly modified 2'-O-DMAOE oligonucleotides may be due to selective interference with the formation of the translational initiation complex. These results demonstrate that 2'-O-DMAOE- modified oligonucleotides are useful for antisense-based therapeutics when either RNase H-dependent or RNase H-independent target reduction mechanisms are employed.

Animals↗

PubMed2004

Heuristic evaluation of infusion pumps: implications for patient safety in Intensive Care Units.

OBJECTIVE: The goal of this research was to use a heuristic evaluation methodology to uncover design and interface deficiencies of infusion pumps that are currently in use in Intensive Care Units (ICUs). Because these infusion systems cannot be readily replaced due to lease agreements and large-scale institutional purchasing procedures, we argue that it is essential to systematically identify the existing usability problems so that the possible causes of errors can be better understood, passed on to the end-users (e.g., critical care nurses), and used to make policy recommendations. DESIGN: Four raters conducted the heuristic evaluation of the three-channel infusion pump interface. Three raters had a cognitive science background as well as experience with the heuristic evaluation methodology. The fourth rater was a veteran critical care nurse who had extensive experience operating the pumps. The usability experts and the domain expert independently evaluated the user interface and physical design of the infusion pump and generated a list of heuristic violations based upon a set of 14 heuristics developed in previous research. The lists were compiled and then rated on the severity of the violation. RESULTS: From 14 usability heuristics considered in this evaluation of the Infusion Pump, there were 231 violations. Two heuristics, "Consistency" and "Language", were found to have the most violations. The one with fewest violations was "Document". While some heuristic evaluation categories had more violations than others, the most severe ones were not confined to one type. The Primary interface location (e.g., where loading the pump, changing doses, and confirming drug settings takes place) had the most occurrences of heuristic violations. CONCLUSION: We believe that the Heuristic Evaluation methodology provides a simple and cost-effective approach to discovering medical device deficiencies that affect a patient's general well being. While this methodology provides information for the infusion pump designs of the future, it also identifies important insights concerning equipment that is currently in use in critical care environments.

Humans↗

PubMed2003

Characterizing information needs and cognitive processes during CIS use.

Medical errors are often associated with inadequate cognitive processing that is based upon impaired access to information.1 Understanding the information needs of nurses and physicians' when using a clinical information system (CIS) is difficult largely because there are few systematic attempts made to do so. We collected 15.5 hours of data of nurses and physicians' CIS interactions in three clinical environments (cardiac ICU, a general medical/surgical nursing, and an ambulatory clinic). We accomplished this through observational, cognitive-based methods (e.g., thinking aloud during interaction) and the video capturing of events with a portable usability laboratory.2 We developed a systematic approach to identify and define in-context clinical information needs while using a CIS, and determine how to categorize and code such events. 3

Cognition↗

PubMedDate not supplied

Medical students' perceptions of psychiatry as a career choice.

OBJECTIVE: This study describes medical students' perceptions of the field of psychiatry and identifies the impact of those perceptions on their career choices in order to explore the questions: Are we as a field doing all that we can to enhance the educational experience of all medical students, regardless of their career preferences? What are the most appropriate ways to encourage interested medical students that would allow for more targeted recruitment efforts toward the most receptive students? METHODS: Third-year (n=131) and fourth-year medical students (n=117) at a northeastern, urban, private university medical school completed anonymous self-report questionnaires. Students rated the impact of intellectual interest, status, earning potential, healthcare reform, quality of life, satisfaction, and stress of working with psychiatric patients on their consideration of a psychiatric career. Respondents were then systematically divided into two groups: 1) those who considered psychiatry as a possible career choice and 2) those who did not. RESULTS: When compared to students who had been coded as "not seriously considering" a career in psychiatry, students coded as "seriously considering" gave significantly higher positive ratings to the field's intellectual content and quality of life. There were also significant differences between the groups regarding the satisfaction involved in working with psychiatric patients. Students from both groups were equally concerned about stress levels in the field. CONCLUSIONS: Acknowledging, discussing, and providing a context for stressful experiences during the psychiatry clerkship are likely to bring about productive approaches to improve recruitment into the field as well as to improve all students' psychiatric education.

Adult↗