Searched for: school:SOM
Department/Unit:Cell Biology
Osteotomy about the knee: applications, techniques, and results
Preston, Charles F; Fulkerson, Eric W; Meislin, Robert; Di Cesare, Paul E
Varus or valgus malalignment of the knee may be either a cause or a consequence of unicompartmental knee arthritis in young, active adults. Proximal tibial osteotomy for the varus knee and distal femoral osteotomy for the valgus knee have been used for decades to manage this condition; however, their use has decreased significantly in recent years as the popularity of unicompartmental and total knee arthroplasty has grown. With the advent of biologic resurfacing techniques for focal full-thickness articular cartilage injury, combined or staged high tibial osteotomy is becoming increasingly popular. In addition, in the face of cruciate ligamentous instability with or without posterolateral corner instability coupled with varus malalignment, high tibial osteotomy with and without ligament reconstruction provides a solution to complex orthopedic problems. Recent long-term follow-up studies have concluded osteotomy allows for improved function and pain relief in properly selected young patients
PMID: 16262007
ISSN: 1538-8506
CID: 62366
Analysis of monomeric GTPases of the Ras and Rho families [Editorial]
Philips, Mark R
PMID: 16289970
ISSN: 1046-2023
CID: 64118
Age-specific behavioral responses to psychostimulants in mice
Niculescu, Michelle; Ehrlich, Michelle E; Unterwald, Ellen M
This study investigated the influence of age on the behavioral responses elicited by psychostimulants in male CD-1 mice. Behavioral activity including locomotion and stereotypy was measured following acute or repeated administration of cocaine, methylphenidate, amphetamine or saline to postweanling (24 days old), periadolescent (33 days old) and adult (60 days old) mice. Postweanling mice exhibited less total and ambulatory activity than periadolescent mice following a single acute injection of cocaine (20 or 30 and 30 mg/kg, respectively). Further, postweanling mice showed less total activity than both periadolescent and adult mice at a dose of 10 mg/kg methylphenidate. Less stereotypy was also seen in postweanling mice when compared to adolescent mice after 30 mg/kg amphetamine. Seven daily injections of cocaine resulted in a heightened behavioral response on day 7 as compared to day 1, indicative of behavioral sensitization in adult and periadolescent, but not postweanling mice. Repeated methylphenidate resulted in increased total activity in adult, but not periadolescent or postweanling mice. None of the animals were sensitized to the behavioral activating effects of amphetamine. The magnitude of behavioral response and the development of sensitization were dependent upon the age of the animal and the agent tested.
PMID: 16199081
ISSN: 0091-3057
CID: 899032
Analysis of Ras and Rap activation in living cells using fluorescent Ras binding domains
Bivona, Trever G; Philips, Mark R
Ras GTPases regulate cellular growth and differentiation and are modulated by myriad stimuli including growth factors, cytokines, antigens, and UV irradiation. Ras GTPases are molecular switches that are active when GTP-bound and inactive when GDP-bound. The ability of these GTPases to signal requires that the GTP-bound form engage downstream effectors, interactions that occur only on the cytosolic surface of cellular membranes. Ras family proteins include H-Ras, N-Ras, K-Ras, and Rap1. Insight into the regulation and signaling properties of these molecules has come largely from in vitro studies relying on cellular extracts prepared following cellular stimulation. Since Ras GTPases are expressed on multiple cellular compartments that include the plasma membrane, vesicles derived from the plasma membrane, and other internal membranes such as the ER and Golgi complex, analysis of how their spatial distribution modulates signaling has remained unknown. We have developed fluorescent, GFP-based probes capable of selectively binding GTP-bound Ras or Rap1 in living cells. We have used these reporters to examine sites of cellular activation of Ras and Rap1 during growth factor stimulation. These studies have revealed new insights into the platforms from which these GTPases signal and have led to the hypothesis that GTPase signaling is modulated in a compartmentalized fashion. Here, we describe the design and implementation of fluorescent probes for Ras and Rap1
PMID: 16289969
ISSN: 1046-2023
CID: 61854
Notch signaling coordinates the patterning of striatal compartments
Mason, Heather A; Rakowiecki, Staci M; Raftopoulou, Myrto; Nery, Susana; Huang, Yuanyuan; Gridley, Thomas; Fishell, Gord
Numerous lines of evidence suggest that Notch signaling plays a pivotal role in controlling the production of neurons from progenitor cells. However, most experiments have relied on gain-of-function approaches because perturbation of Notch signaling results in death prior to the onset of neurogenesis. Here, we examine the requirement for Notch signaling in the development of the striatum through the analysis of different single and compound Notch1 conditional and Notch3 null mutants. We find that normal development of the striatum depends on the presence of appropriate Notch signals in progenitors during a critical window of embryonic development. Early removal of Notch1 prior to neurogenesis alters early-born patch neurons but not late-born matrix neurons in the striatum. We further show that the late-born striatal neurons in these mutants are spared as a result of functional compensation by Notch3. Notably, however, the removal of Notch signaling subsequent to cells leaving the germinal zone has no obvious effect on striatal organization and patterning. These results indicate that Notch signaling is required in neural progenitor cells to control cell fate in the striatum, but is dispensable during subsequent phases of neuronal migration and differentiation
PMID: 16120638
ISSN: 0950-1991
CID: 61255
Synthesis of glycopeptides from type II collagen-incorporating galactosylated hydroxylysine mimetics and their use in studying the fine specificity of arthritogenic T cells
Marin, Julien; Blaton, Marie-Agnes; Briand, Jean-Paul; Chiocchia, Gilles; Fournier, Catherine; Guichard, Gilles
Five analogues of the bovine type II collagen (bCII) immunodominant glycopeptide [beta-D-Gal-(5R)-5-Hyl264]CII(256-270) (1) carrying diverse modifications at the critical hydroxylysine (Hyl) 264 side chain were designed and synthesised, to explore the fine specificity of bCII-reactive T cells involved in the initiation and/or regulation of collagen-induced arthritis (CIA), a mouse model for rheumatoid arthritis (RA). Beta-D-galactosyl-(5R)-5-hydroxy-L-lysine (19) and corresponding mimetics (22-25), conveniently protected for solid-phase synthesis, were all obtained by a divergent route involving enantiopure 5-hydroxylated 6-oxo-1,2-piperidinedicarboxylates as the key intermediates. All three bCII-specific T hybridomas used, as well as a recurrent pathogenic CD4+ T-cell clone isolated from bCII-immunised DBA/1 mice, recognised the galactosylated form 1 of the immunodominant bCII (256-270) epitope. These cells were extremely sensitive to changes at the epsilon-amino group of Hyl264, but differed in their pattern of recognition of analogues with a Hyl264 side chain modified at C-5 (i.e. inversion of stereochemistry, methylation). These data further document the importance of collagen post-translational modifications in autoimmunity and in the CIA model in particular, and provide a new insight into the molecular interaction between glycopeptide 1 and the TCR of pathogenic T cells.
PMID: 16116660
ISSN: 1439-4227
CID: 2184102
Heightened stress response in primary fibroblasts expressing mutant eIF2B genes from CACH/VWM leukodystrophy patients
Kantor, Liraz; Harding, Heather P; Ron, David; Schiffmann, Raphael; Kaneski, Christine R; Kimball, Scot R; Elroy-Stein, Orna
Childhood ataxia with central nervous system hypomyelination (CACH), also called vanishing white matter (VWM) leukoencephalopathy, is a fatal genetic disease caused by mutations in eukaryotic initiation factor 2B (eIF2B) genes. The five subunits eIF2B factor is critical for translation initiation under normal conditions and regulates protein synthesis in response to cellular stresses. Primary fibroblasts from CACH/VWM patients and normal individuals were used to measure basal eIF2B activity as well as global protein synthesis and ATF4 induction in response to stress in the endoplasmic reticulum. We show that although the cells expressing mutant eIF2B genes respond normally to stress conditions by reduced global translation rates, they exhibit significantly greater increase in ATF4 induction compared to normal controls despite equal levels of stress and activity of the upstream eIF2alpha kinase. This heightened stress response observed in primary fibroblasts that suffer from minor loss of basal eIF2B activity may be employed as an initial screening tool for CACH/VWM leukodystrophy.
PMID: 16041584
ISSN: 0340-6717
CID: 72847
[GCN2 regulates feeding behavior to maintain amino acid homeostasis in omnivores]
Maurin, Anne-Catherine; Jousse, Celine; Balage, Michelle; Averous, Julien; Parry, Laurent; Bruhat, Alain; Cherasse, Yoan; Zeng, Huiqing; Zhang, Yuhong; Harding, Heather; Ron, David; Fafournoux, Pierre
PMID: 16197891
ISSN: 0767-0974
CID: 71603
Pregnancy outcome in in vitro fertilization decreases to a plateau with repeated cycles
Silberstein, Tali; Trimarchi, James R; Gonzalez, Liliana; Keefe, David L; Blazar, Andrew S
Clinical pregnancy rate (CPR) and implantation rate (IR) in 1,177 patients who had 1,788 fresh, nondonor, nonPGD IVF cycles were highest in cycle 1, significantly declined in cycle 2, and reached a plateau for cycles 3-5 at a rate lower than in cycle 2. In patients >38 years of age CPR and IR in cycles 1 and 2 were significantly lower than in younger patients, but there was no decline in CPR or IR with advancing IVF attempts
PMID: 16213871
ISSN: 1556-5653
CID: 101987
Autophagy in chronically ischemic myocardium
Yan, Lin; Vatner, Dorothy E; Kim, Song-Jung; Ge, Hui; Masurekar, Malthi; Massover, William H; Yang, Guiping; Matsui, Yutaka; Sadoshima, Junichi; Vatner, Stephen F
We tested the hypothesis that chronically ischemic (IS) myocardium induces autophagy, a cellular degradation process responsible for the turnover of unnecessary or dysfunctional organelles and cytoplasmic proteins, which could protect against the consequences of further ischemia. Chronically instrumented pigs were studied with repetitive myocardial ischemia produced by one, three, or six episodes of 90 min of coronary stenosis (30% reduction in baseline coronary flow followed by reperfusion every 12 h) with the non-IS region as control. In this model, wall thickening in the IS region was chronically depressed by approximately 37%. Using a nonbiased proteomic approach combining 2D gel electrophoresis with in-gel proteolysis, peptide mapping by MS, and sequence database searches for protein identification, we demonstrated increased expression of cathepsin D, a protein known to mediate autophagy. Additional autophagic proteins, cathepsin B, heat shock cognate protein Hsc73 (a key protein marker for chaperone-mediated autophagy), beclin 1 (a mammalian autophagy gene), and the processed form of microtubule-associated protein 1 light chain 3 (a marker for autophagosomes), were also increased. These changes, not evident after one episode, began to appear after two or three episodes and were most marked after six episodes of ischemia, when EM demonstrated autophagic vacuoles in chronically IS myocytes. Conversely, apoptosis, which was most marked after three episodes, decreased strikingly after six episodes, when autophagy had increased. Immunohistochemistry staining for cathepsin B was more intense in areas where apoptosis was absent. Thus, autophagy, triggered by ischemia, could be a homeostatic mechanism, by which apoptosis is inhibited and the deleterious effects of chronic ischemia are limited.
PMCID:1224362
PMID: 16174725
ISSN: 0027-8424
CID: 610562