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J Lawrence Marsh

Publications and source records attributed to J Lawrence Marsh.

At least 37 records · Page 2Linked to original sources
PubMed2004

High-resolution mapping of the Drosophila fourth chromosome using site-directed terminal deficiencies.

For more than 80 years, the euchromatic right arm of the Drosophila fourth chromosome (101F-102F) has been one of the least genetically accessible regions of the fly genome despite the fact that many important genes reside there. To improve the mapping of genes on the fourth chromosome, we describe a strategy to generate targeted deficiencies and we describe 13 deficiencies that subdivide the 300 kb between the cytological coordinates 102A6 and 102C1 into five discrete regions plus a 200-kb region from 102C1 to 102D6. Together these deficiencies substantially improve the mapping capabilities for mutant loci on the fourth chromosome.

Animals↗
PubMed2004

Molecular mapping of deletion breakpoints on chromosome 4 of Drosophila melanogaster.

As part of our effort to induce and identify mutations in all genes on chromosome 4 of Drosophila melanogaster, we have mapped the breakpoints of eight chromosome 4 deficiencies relative to the predicted genes along this chromosome. Although the approximate locations of Df(4)G, Df(4)C3, Df(4)M101-62f, Df(4)M101-63a, Df(4)J2, Df(4)O2, Df(4)C1-10AT, and Df(4)B2-2D are known (some from cytological observations and others predicted from P element locations), the extents of these deletions have not been mapped with respect to the predicted genes identified by the Drosophila Genome Project. Polymerase chain reaction primers were designed to amplify the predicted exons of all chromosome 4 genes, and homozygous embryos for each deficiency were identified and their DNA used to test for the presence or absence of these exons. By testing for the inability to amplify various exons along the length of the chromosome, we were able to determine which predicted genes are missing in each deficiency. The five deficiencies, Df(4)G, Df(4)C3, Df(4)C1-10AT, and Df(4)B2-20 (all terminal deletions), and Df(4)M101-62f (a proximal interstitial deletion), enabled us to partition the gene-containing, right arm of chromosome 4 into five regions. Region A [uncovered by Df(4)M101-62f] contains the proximal-most 21 genes; region B [uncovered by Df(4)B2-2D] contains the next 12 genes; region C [uncovered by Df(4)B2-2D and Df(4)C1-10AT] contains the next 17 genes; region D [uncovered by Df(4)B2-2D, Df(4)C1-10AT, and Df(4)C3] contains the next 21 genes; and region E [uncovered by Df(4)B2-2D, Df(4)C1-10AT, Df(4)C3, and Df(4)G] contains the distal-most ten genes. By using Df(4)M101-62f, Df(4)B2-2D, Df(4)C1-10AT, Df(4)C3, and Df(4)G in complementation tests, we can assign newly induced recessive lethal mutations to one of the five regions on chromosome 4. This will substantially reduce the amount of DHPLC analysis required to match each mutation to a predicted transcript on chromosome 4.

Animals↗
PubMed2004

SUMO modification of Huntingtin and Huntington's disease pathology.

Huntington's disease (HD) is characterized by the accumulation of a pathogenic protein, Huntingtin (Htt), that contains an abnormal polyglutamine expansion. Here, we report that a pathogenic fragment of Htt (Httex1p) can be modified either by small ubiquitin-like modifier (SUMO)-1 or by ubiquitin on identical lysine residues. In cultured cells, SUMOylation stabilizes Httex1p, reduces its ability to form aggregates, and promotes its capacity to repress transcription. In a Drosophila model of HD, SUMOylation of Httex1p exacerbates neurodegeneration, whereas ubiquitination of Httex1p abrogates neurodegeneration. Lysine mutations that prevent both SUMOylation and ubiquitination of Httex1p reduce HD pathology, indicating that the contribution of SUMOylation to HD pathology extends beyond preventing Htt ubiquitination and degradation.

Animals↗
PubMed2004

Levodopa-responsive aromatic L-amino acid decarboxylase deficiency.

We report three siblings, who were treated empirically with levodopa combined with carbidopa. There was an immediate therapeutic response. Biochemical investigation surprisingly showed the clinical phenotype to be caused by aromatic L-amino acid decarboxylase deficiency. Molecular characterization showed a homozygous point mutation (c.387 G-->A) in exon 3. Kinetic studies showed the mutation to decrease the binding affinity for the substrate. This, combined with structural modeling suggesting alteration of active site configuration, provided an explanation for the therapeutic response to levodopa.

Adolescent↗
PubMed2004

Can flies help humans treat neurodegenerative diseases?

Neurodegenerative diseases are becoming increasingly common as life expectancy increases. Recent years have seen tremendous progress in the identification of genes that cause these diseases. While mutations have been found and cellular processes defined that are altered in the disease state, the identification of treatments and cures has proven more elusive. The process of finding drugs and therapies to treat human diseases can be slow, expensive and frustrating. Can model organisms such as Drosophila speed the process of finding cures and treatments for human neurodegenerative diseases? We pose three questions, (1) can one mimic the essential features of human diseases in an organism like Drosophila, (2) can one cure a model organisms of human disease and (3) will these efforts accelerate the identification of useful therapies for testing in mice and ultimately humans? Here we focus on the use of Drosophila to identify potential treatments for neurodegenerative diseases such as Huntington's and we discuss how well these therapies translate into mammalian systems.

Animals↗
PubMed2004

Hinged external fixation of the knee: intrinsic factors influencing passive joint motion.

OBJECTIVE: To measure changes in knee kinematics after the application of articulated external fixators along a previously described knee flexion/extension axis and 16 specific "off-axis" fixator hinge configurations. DESIGN: Cadaver, biomechanical study. SETTING: Biomechanics laboratory. PARTICIPANTS: Nine fresh cadaver knee specimens. INTERVENTION: Each specimen was mounted on a custom-built frame that constrained the knee to move about a fixed flexion/extension axis. Passive knee motion was induced, and the resulting flexion moment was measured. Data were collected for the on-axis fixator position and 16 distinct rotational and translational off-axis positions. In addition, effects of tibial translation and rotation were investigated. MAIN OUTCOME: Range of motion (ROM) attainable within a moment envelope of +/-1 N-m and average energy required to impart movement. RESULTS: The average ROM for unconstrained knees was 122 degree. Constraining the knee to rotation around an on-axis aligned hinge significantly reduced the ROM by 35% to 79 degree. The 5-mm posterior translated hinge was the only alignment to show on average a slightly larger ROM (86 degree) than the on-axis hinge. All other hinge alignments showed decreased average ROM compared with the on-axis position. Tibiofemoral alignments significantly affected the obtainable ROM for the on-axis aligned hinge. CONCLUSION: It was not possible to replicate precisely the complex kinematics of the knee using a single axis fixator over the entire ROM. Using the axis of rotation previously defined in the literature, however, it was possible to obtain a limited ROM of the knee without placing excessive forces on the periarticular structures.

Aged↗
PubMed2004

Factors affecting outcome in tibial plafond fractures.

To determine what fracture- and patient-specific variables affect outcome, 29 patients with 32 tibial plafond fractures were evaluated at a minimum of 2 years from the time of injury (range, 24-129 months; average, 46.5 months). The rank order method was used to assess severity of injury and accuracy of articular reduction on radiographs and agreement among the five surgeons was excellent with intraclass correlation coefficients of 0.93 and 0.94. Outcome was assessed by four independent measures: a radiographic arthrosis score, a subjective ankle score, the Short Form-36 (SF-36), and the patient's ability to return to work. The four outcome measures did not correlate with each other. Radiographic arthrosis was predicted best by severity of injury and accuracy of reduction. However, these variables did not show any significant relationship to the clinical ankle score, the SF-36, or return to work. These outcome measures were more influenced by patient-specific socioeconomic factors. Higher ankle scores were seen in patients with college degrees and lower scores were seen in patients with a work-related injury. The ability to return to work was affected by the patient's level of education. This study highlights the difficulties of predicting patient outcome, after these severe articular fractures.

Adolescent↗
PubMed2004

Particulate debris osteolysis simulating malignant tumor.

Osteolysis induced by particulate debris from total joint implants is typically confined to bone and benign in radiographic appearance even when extensive. However, they can extend well beyond bone in which case they can simulate malignancies owing either to mass effects and pressure on adjacent tissues or owing to the radiographic appearance. We report two cases which presented as possible malignancy, and review the literature on extensive osteolysis. Recognition of this possibility may aid in interpretation of the clinical presentation and imaging studies.

Adult↗
PubMed2004

Expression of Wnt genes and frizzled 1 and 2 receptors in normal breast epithelium and infiltrating breast carcinoma.

The Wnt genes encode a family of related, secreted proteins which initiate a signal cascade upon binding to cell surface receptor molecules. The signaling pathway has been shown to be critical for normal growth and development in model organisms and is implicated in the genesis of numerous human cancers. Wnt proteins regulate mammary development in the mouse but their precise role in normal breast development and malignant transformation in humans remains poorly defined. In this study, we have examined the expression of several Wnt ligands by in situ anti-sense RNA hybridization in normal and malignant human breast tissue, as well as in several estrogen-responsive and estrogen-independent human breast cancer cell lines. The specific Wnt genes tested included Wnt1, Wnt2, Wnt4, Wnt5a, Wnt5b, Wnt6, Wnt7b and Wnt10b. We have also studied the expression of frizzled receptors 1 and 2 by immunohistochemistry in these tissues. Our results indicate that several of the Wnt ligands, especially Wnt1 and Wnt6, are strongly expressed in both normal and malignant breast tissue and that Wnt7b is down-regulated in breast cancer, compared to normal breast epithelium. The expression of frizzled 1 and 2 receptors was found to be up-regulated in breast cancer. These studies provide additional support to the hypothesis that the Wnt signaling pathway is involved in human breast cancer.

Breast Neoplasms↗
PubMed2003

A rapid cellular FRET assay of polyglutamine aggregation identifies a novel inhibitor.

Many neurodegenerative diseases, including tauopathies, Parkinson's disease, amyotrophic lateral sclerosis, and the polyglutamine diseases, are characterized by intracellular aggregation of pathogenic proteins. It is difficult to study modifiers of this process in intact cells in a high-throughput and quantitative manner, although this could facilitate molecular insights into disease pathogenesis. Here we introduce a high-throughput assay to measure intracellular polyglutamine protein aggregation using fluorescence resonance energy transfer (FRET). We screened over 2800 biologically active small molecules for inhibitory activity and have characterized one lead compound in detail. Y-27632, an inhibitor of the Rho-associated kinase p160ROCK, diminished polyglutamine protein aggregation (EC(50) congruent with 5 microM) and reduced neurodegeneration in a Drosophila model of polyglutamine disease. This establishes a novel high-throughput approach to study protein misfolding and aggregation associated with neurodegenerative diseases and implicates a signaling pathway of previously unrecognized importance in polyglutamine protein processing.

Amides↗
PubMed2003

Fly models of Huntington's disease.

Can Drosophila models be engineered that accurately reflect Huntington's disease (HD) and other neurological diseases and can they contribute to the search for treatments and cures? A number of publications seem to provide a resounding yes to that question. Here we seek to review some of the salient features of these models.

Animals↗
PubMed2003

A cell-based assay for aggregation inhibitors as therapeutics of polyglutamine-repeat disease and validation in Drosophila.

The formation of polyglutamine-containing aggregates and inclusions are hallmarks of pathogenesis in Huntington's disease that can be recapitulated in model systems. Although the contribution of inclusions to pathogenesis is unclear, cell-based assays can be used to screen for chemical compounds that affect aggregation and may provide therapeutic benefit. We have developed inducible PC12 cell-culture models to screen for loss of visible aggregates. To test the validity of this approach, compounds that inhibit aggregation in the PC12 cell-based screen were tested in a Drosophila model of polyglutamine-repeat disease. The disruption of aggregation in PC12 cells strongly correlates with suppression of neuronal degeneration in Drosophila. Thus, the engineered PC12 cells coupled with the Drosophila model provide a rapid and effective method to screen and validate compounds.

Animals↗
PubMed2003

Suberoylanilide hydroxamic acid, a histone deacetylase inhibitor, ameliorates motor deficits in a mouse model of Huntington's disease.

Huntington's disease (HD) is an inherited, progressive neurological disorder that is caused by a CAG/polyglutamine repeat expansion and for which there is no effective therapy. Recent evidence indicates that transcriptional dysregulation may contribute to the molecular pathogenesis of this disease. Supporting this view, administration of histone deacetylase (HDAC) inhibitors has been shown to rescue lethality and photoreceptor neurodegeneration in a Drosophila model of polyglutamine disease. To further explore the therapeutic potential of HDAC inhibitors, we have conducted preclinical trials with suberoylanilide hydroxamic acid (SAHA), a potent HDAC inhibitor, in the R6/2 HD mouse model. We show that SAHA crosses the blood-brain barrier and increases histone acetylation in the brain. We found that SAHA could be administered orally in drinking water when complexed with cyclodextrins. SAHA dramatically improved the motor impairment in R6/2 mice, clearly validating the pursuit of this class of compounds as HD therapeutics.

Acetylation↗
PubMed2003

Invertebrate models of neurologic disease: insights into pathogenesis and therapy.

The search for cures of human diseases can be very slow, expensive, and serendipitous. Roughly five decades of basic research in a handful of model systems has revealed that most animals are quite similar to one another especially at the cellular and molecular levels. The commonalities allow one to use animal models to investigate human disease mechanisms. Here, we review contributions demonstrating the use of invertebrate models to investigate human neurodegenerative diseases. We conclude that the integration of fly and worm models into programs seeking to identify therapeutic strategies for neurodegenerative disease can significantly speed progress toward finding cures for these devastating diseases.

Animals↗
PubMed2003

Acute pain treatment for older adults hospitalized with hip fracture: current nursing practices and perceived barriers.

This article examines acute pain management practices for patients 65 years of age and older who were hospitalized during 1999 for hip fracture. Data were collected from the medical records of patients (N = 709) admitted to 12 hospitals in the Midwest and from questionnaires on pain practices completed by nurses (N = 172) caring for these patients. The major variables examined were (1). pharmacological and nonpharmacological treatments for acute pain in hospitalized elders, (2). nurses' perceived stage of adoption for avoiding meperidine use and for administering analgesics around-the-clock, and (3). nurses' perceived barriers to optimal treatment of acute pain in elders. Acetaminophen was the most frequently administered analgesic, but administered doses were far less than the maximum daily recommended dose. More than one third (39%) of the nurses reported that they always avoided the use of meperidine, and over half reporting avoiding its use sometimes. However, the majority of patients (56.8%) received at least one dose of meperidine, even though evidence suggests that other analgesic agents are more appropriate for treatment of acute pain in elders. Only 27% of patients received patient-controlled analgesia, and only 22.3% of patients received around-the-clock administration during the first 24 hours after admission of analgesics that had been ordered on a prn basis. The majority of nurses were aware that around-the-clock administration of analgesics was preferable, but only 33.7% were persuaded (believed) that this method should be used. Intramuscular injection was used for 52.2% of patients, even though this route is not recommended for older adults. The most frequently used nonpharmacological intervention was repositioning, followed by use of pressure relief devices and cold application. Nurses reported difficulty contacting physicians and difficulty communicating with them about type and/or dose of analgesics as the greatest barriers to pain management. Findings from this multi-site study show that active and focused "translation" interventions are needed to promote adoption of evidence-based acute pain management practices by health care providers.

Acute Disease↗
PubMed2003

Tibial plafond fractures. How do these ankles function over time?

BACKGROUND: The intermediate outcome of fractures of the tibial plafond treated with current techniques has not been reported, to our knowledge. The purpose of this study, performed at a minimum of five years after injury, was to determine the effect of these fractures on ankle function, pain, and general health status and to determine which factors predict favorable and unfavorable outcomes. METHODS: Fifty-six ankles (fifty-two patients) with a tibial plafond fracture were treated with a uniform technique consisting of application of a monolateral hinged transarticular external fixator coupled with screw fixation of the articular surface. Thirty-one patients with thirty-five involved ankles returned between five and twelve years after the injury for a physical examination, assessment of ankle pain and function with the Iowa Ankle Score and Ankle Osteoarthritis Scale, assessment of general health status with the Short Form-36 (SF-36), and radiographic examination of the ankle. RESULTS: Arthrodesis had been performed on five of the forty ankles for which the outcome was known at a minimum of five years after the injury. Other than removal of prominent screws (two patients), no other surgical procedure had been performed on any patient. The average Iowa Ankle Score was 78 points (range, 28 to 96 points). The scores on the SF-36 and Ankle Osteoarthritis Scale demonstrated a long-term negative effect of the injury on general health and on ankle pain and function when compared with those parameters in age-matched controls. The degree of osteoarthrosis was grade 0 in three ankles, grade 1 in six, grade 2 in twenty, and grade 3 in six. The majority of patients had some limitation with regard to recreational activities, with an inability to run being the most common complaint (twenty-seven of the thirty-one patients). Fourteen patients changed jobs because of the ankle injury. Fifteen ankles were rated by the patient as excellent; ten, as good; seven, as fair; and one, as poor. Nine patients with previously recorded ankle scores had better scores after the longer follow-up interval. The patients perceived that their condition had improved for an average of 2.4 years after the injury. CONCLUSIONS: Although tibial plafond fractures have an intermediate-term negative effect on ankle function and pain and on general health, few patients require secondary reconstructive procedures and symptoms tend to decrease for a long time after healing.

Adult↗