Faculty Bibliography

Dendron G1(Gu(+))(9)R and linear peptide oligomer Asn(TEG-Gu(+))(9), decorated with multiple guanidinium (Gu(+)) ions as sticky pendants via an oligo(oxyethylene) spacer, adhere to BSA and protein assemblies such as microtubules in aqueous buffers. Using fluorescently labeled G1(Gu(+))(9)R with pyrenyl and rhodamine focal cores, the adhesion process can be visualized by FRET or confocal laser scanning microscopy. The adhesion to microtubules leads to their stabilization against depolymerization into alpha/beta-tubulin heterodimer components, where the effects of G1(Gu(+))(9)R and Asn(TEG-Gu(+))(9) are comparable to that of paclitaxel, known as an anticancer drug. Since G1(Gu(+))(9)R and Asn(TEG-Gu(+))(9) are superior to lower-generation G0(Gu(+))(3)OMe and arginine nonamer, respectively, the multivalency of the interaction and a conformational flexibility of the oligoether spacers play a crucial role in the efficient adhesion to proteins.

Diverse cellular stress responses are linked to phosphorylation of serine 51 on the alpha subunit of translation initiation factor 2. The resultant attenuation of protein synthesis and activation of gene expression figure heavily in the adaptive response to stress, but dephosphorylation of eIF2(alphaP), which terminates signaling in this pathway, is less well understood. GADD34 and CReP, the products of the related mammalian genes Ppp1r15a and Ppp1r15b, can recruit phosphatase catalytic subunits of the PPP1 class to eIF2(alphaP), but the significance of their contribution to its dephosphorylation has not been explored systematically. Here we report that unlike Ppp1r15a mutant mice, which are superficially indistinguishable from wild type, Ppp1r15b(-/-) mouse embryos survive gestation but exhibit severe growth retardation and impaired erythropoiesis, and loss of both Ppp1r15 genes leads to early embryonic lethality. These loss-of-function phenotypes are rescued by a mutation, Eif2a(S51A), that prevents regulated phosphorylation of eIF2alpha. These findings reveal that the essential process of eIF2(alphaP) dephosphorylation is the predominant role of PPP1R15 proteins in mammalian development

Hair follicles (HFs) undergo cyclic bouts of degeneration, rest, and regeneration. During rest (telogen), the hair germ (HG) appears as a small cell cluster between the slow-cycling bulge and dermal papilla (DP). Here we show that HG cells are derived from bulge stem cells (SCs) but become responsive quicker to DP-promoting signals. In vitro, HG cells also proliferate sooner but display shorter-lived potential than bulge cells. Molecularly, they more closely resemble activated bulge rather than transit-amplifying (matrix) cells. Transcriptional profiling reveals precocious activity of both HG and DP in late telogen, accompanied by Wnt signaling in HG and elevated FGFs and BMP inhibitors in DP. FGFs and BMP inhibitors participate with Wnts in exerting selective and potent stimuli to the HG both in vivo and in vitro. Our findings suggest a model where HG cells fuel initial steps in hair regeneration, while the bulge is the engine maintaining the process

Clostridium botulinum neurotoxin (BoNT) is the causative agent of botulism, a neuroparalytic disease. We describe here a semisynthetic strategy to identify inhibitors based on toosendanin, a traditional Chinese medicine reported to protect from BoNT intoxication. Using a single molecule assay of BoNT serotypes A and E light chain (LC) translocation through the heavy chain (HC) channel in neurons, we discovered that toosendanin and its tetrahydrofuran analog selectively arrest the LC translocation step of intoxication with subnanomolar potency, and increase the unoccluded HC channel propensity to open with micromolar efficacy. The inhibitory profile on LC translocation is accurately recapitulated in 2 different BoNT intoxication assays, namely the mouse protection and the primary rat spinal cord cell assays. Toosendanin has an unprecedented dual mode of action on the protein-conducting channel acting as a cargo-dependent inhibitor of translocation and as cargo-free channel activator. These results imply that the bimodal modulation by toosendanin depends on the dynamic interactions between channel and cargo, highlighting their tight interplay during the progression of LC transit across endosomes.

Aripiprazole is commonly used as an atypical antipsychotic. It has been associated with abnormalities in glucose metabolism. Severe diabetic complications associated with its use occur rarely. We present a case of a patient without a history of diabetes mellitus who presented to the emergency department in severe hyperosmolar nonketotic coma while using aripiprazole

OBJECTIVES: To illustrate the correlations and effects of age, gender and cause of accident on the type of vertebral fracture and fracture distribution, as well as on the likelihood to sustain an associated injury or neurological deficit. DESIGN: Retrospective analysis of 562 patients with a traumatic fracture of the spine. Each patient was analysed by reviewing the medical records, the initial radiographs and CT-scans. SETTING: Level 1 trauma centre from 01/1996 to 12/2000. RESULTS: The most common cause of accident was a high-energy fall (39%), followed by traffic accidents (26.5%). While fall related fractures were evenly distributed over the whole spine, traffic accidents induced significantly more fractures of the cervical and thoracic spine. Sixty-five percent of all cervical spine fractures and 80% of the multisegmental injuries were accompanied by an associated injury. The highest incidence of associated injuries was observed in patients with multilevel fractures (96.5%). Patients with a concomitant injury were more likely to sustain a spinal cord lesion. Sixty-three (11.2%) patients exhibited a complete motor and sensory deficit, 76 (13.5%) an incomplete and 423 (75.3%) no neurological deficit. The highest number of complete motor and sensory neurological deficits was found in cervical spine fractures (19.7%). The majority of patients, 308 (54.8%), sustained a compression fracture, 95 (16.9%) a distraction fracture, and 104 (18.5%) patients experienced a rotational fracture. CONCLUSIONS: This study demonstrates correlations between the cause of accident, the type of spinal fracture and the fracture distribution. Using the AO classification, the likelihood to sustain either associated and/or spinal cord injuries, is predictable.

Three cases of fractured uncemented, fully porous Echelon femoral stems (Smith & Nephew, Memphis, Tenn) are examined. Fracture of these components, an uncommon complication of revision hip surgery, is thought to result from cantilever bending after distal bony ingrowth. The stems in these cases fractured at 11, 22, and 28 months after revision surgery. Risk factors include increased body weight, excessive activity, an undersized stem, varus alignment, inadequate proximal femoral bone stock, and metallurgic defects. Extraction can be difficult and is often accomplished with the use of multiple trephines or via tamping through a distal cortical window

BACKGROUND & AIMS: Increased vascular density has been associated with progression of human inflammatory bowel diseases (IBDs) and animal models of colitis. Pathologic angiogenesis in chronically inflamed tissues is mediated by several factors that are regulated at specialized lipid rafts known as caveolae. Caveolin-1 (Cav-1), the major structural protein of caveolae in endothelial cells, is involved in the regulation of angiogenesis, so we investigated its role in experimental colitis. METHODS: Colitis was induced by administration of dextran sodium sulfate to wild-type and Cav-1(-/-) mice, as well as Cav-1(-/-) mice that overexpress Cav-1 only in the endothelium. Colon tissues were analyzed by histologic analyses. Leukocyte recruitment was analyzed by intravital microscopy; angiogenesis was evaluated by immunohistochemistry and in vivo disk assays. RESULTS: Cav-1 protein levels increased after the induction of colitis in wild-type mice. In Cav-1(-/-) mice or mice given a Cav-1 inhibitory peptide, the colitis histopathology scores, vascular densities, and levels of inflammatory infiltrates decreased significantly compared with controls. Lower levels of leukocyte and platelet rolling and adhesion colitis also were observed in Cav-1(-/-) mice and mice given a Cav-1 inhibitory peptide, compared with controls. Cav-1(-/-) mice that received transplants of wild-type bone marrow had a lower colitis score than wild-type mice. Data from mice that overexpress Cav-1 only in the endothelium indicated that endothelial Cav-1 is the critical regulator of colitis. Genetic deletion or pharmacologic inhibition of endothelial Cav-1 also significantly decreased vascular densities and angiogenesis scores, compared with controls. CONCLUSIONS: Endothelial Cav-1 mediates angiogenesis in experimental colitis. Modulation of Cav-1 could provide a novel therapeutic target for IBD

During mammalian fertilization sperm bind to the egg's zona pellucida (ZP) after undergoing capacitation. Capacitated mouse sperm bind to mZP3 (one of three ZP glycoproteins), undergo the acrosome reaction, penetrate the ZP, and fuse with egg plasma membrane. Sperm protein 56 (sp56), a member of the C3/C4 superfamily of binding proteins, was identified nearly 20 years ago as a binding partner for mZP3 by photoaffinity cross-linking of acrosome-intact sperm. However, subsequent research revealed that sp56 is a component of the sperm's acrosomal matrix and, for sperm with an intact acrosome, should be unavailable for binding to mZP3. Recently, this dilemma was resolved when it was recognized that some acrosomal matrix (AM) proteins, including sp56, are released to the sperm surface during capacitation. This may explain why uncapacitated mammalian sperm are unable to bind to the unfertilized egg ZP.