Faculty Bibliography

The coxsackievirus and adenovirus receptor (CAR) is a cell surface protein that is proposed to be involved in cell-cell adhesion. Based on a yeast two-hybrid screen, co-immunoprecipitation and binding experiments, the intracellular tail of CAR was found to interact both in vivo and in vitro with the Ligand-of-Numb Protein-X2 (LNX2). The interacting domains between the two proteins were identified by truncation analyses and affinity chromatography. CAR and LNX2 protein expression in embryonic mouse tissues was analyzed by immunohistochemistry. The results suggest that CAR is a partner in a protein complex organized at specific subcellular sites by LNX2

The signals that determine whether axons are ensheathed or myelinated by Schwann cells have long been elusive. We now report that threshold levels of neuregulin-1 (NRG1) type III on axons determine their ensheathment fate. Ensheathed axons express low levels whereas myelinated fibers express high levels of NRG1 type III. Sensory neurons from NRG1 type III deficient mice are poorly ensheathed and fail to myelinate; lentiviral-mediated expression of NRG1 type III rescues these defects. Expression also converts the normally unmyelinated axons of sympathetic neurons to myelination. Nerve fibers of mice haploinsufficient for NRG1 type III are disproportionately unmyelinated, aberrantly ensheathed, and hypomyelinated, with reduced conduction velocities. Type III is the sole NRG1 isoform retained at the axon surface and activates PI 3-kinase, which is required for Schwann cell myelination. These results indicate that levels of NRG1 type III, independent of axon diameter, provide a key instructive signal that determines the ensheathment fate of axons

Sensory neurons with related functions form ganglia, but how these precisely positioned clusters are assembled has been unclear. Here, we use the zebrafish trigeminal sensory ganglion as a model to address this question. We find that some trigeminal sensory neurons are born at the position where the ganglion is assembled, whereas others are born at a distance and have to migrate against opposing morphogenetic movements to reach the site of ganglion assembly. Loss of Cxcr4b-mediated chemokine signaling results in the formation of mispositioned ganglia. Conversely, ectopic sources of the chemokine SDF1a can attract sensory neurons. Transplantation experiments reveal that neuron-neuron interaction and the adhesion molecules E- and N-Cadherin also contribute to ganglion assembly. These results indicate that ganglion formation depends on the interplay of birthplace, chemokine attraction, cell-cell interaction, and cadherin-mediated adhesion

Spatial events largely determine the biology of cells, tissues, and organs. In this paper, we present a tool for the quantitative spatial analysis of heterogeneous cell populations, and we show experimental validation of this tool using both artificial and real (mammary gland tissue) data, in two and three dimensions. We present the refined relative neighborhood graph as a means to establish neighborhood between cells in an image while modeling the topology of the tissue. Then, we introduce the M function as a method to quantitatively evaluate the existence of spatial patterns within one cell population or the relationship between the spatial distributions of multiple cell populations. Finally, we show a number of examples that demonstrate the feasibility of our approach

Urothelium that lines almost the entire urinary tract acts as a permeability barrier and is involved in the pathogenesis of major urinary diseases including urothelial carcinoma, urinary tract infection and interstitial cystitis. However, investigation of urothelial biology and diseases has been hampered by the lack of tissue-specific approaches. To address this deficiency, we sought to develop a urothelium-specific knockout system using the Cre/loxP strategy. Transgenic mouse lines were generated in which a 3.6-kb mouse uroplakin II (UPII) promoter was used to drive the expression of Cre recombinase (Cre). Among the multiple tissues analyzed, Cre was found to be expressed exclusively in the urothelia of the transgenic mice. Crossing a UPII-Cre transgenic line with a ROSA26-LacZ reporter line, in which LacZ expression depends on Cre-mediated deletion of a floxed 'stop' sequence, led to LacZ expression only in the urothelium. Gene recombination was also observed when the UPII-Cre line was crossed to an independent line in which a part of the p53 gene was flanked by the loxP sequences (floxed p53). Truncation of the p53 gene and mRNA were observed exclusively in the urothelia of double transgenic mice harboring both the UPII-Cre transgene and the floxed p53 allele. These results demonstrate for the first time the feasibility and potentially wide applicability of the UPII-Cre transgenic mice to inactivate any genes of interest in the urothelium

Studies on the relationship between female testosterone (T) measures and behavior, particularly in free-ranging primate populations, remain scant. In this study we used fecal steroid analysis to examine the effects of seasonal, reproductive, and social factors on female T in a group of free-ranging hybrid baboons (Papio sp.) in the Awash National Park of Ethiopia. We collected behavioral and hormonal data from 25 adult females across an 11-month period. Solid phase extraction and radioimmunoassay (RIA) techniques were used to quantify T in 776 fecal samples collected weekly from each female. The results indicate that 1) the females had elevated T during pregnancy and during the wet season relative to other periods, 2) female dominance rank was positively related to T measures, and 3) female T and aggression were positively related within subjects but not across subjects. Higher T concentrations during pregnancy are consistent with other published profiles of pregnancy in primates. In combination with data on foraging, wet season increases in T may indicate contest competition for females. The rank-T relationship may be mediated by supplants or aggression. Finally, we discuss the different interpretations of the hormone-behavior relationship based on within- and across-subject analyses.

OBJECTIVE: To investigate whether two different multiphasic implants could initiate and sustain repair of osteochondral defects in rabbits. The implants address the malleable properties of cartilage while also addressing the rigid characteristics of subchondral bone. DESIGN: The bone region of both devices consisted of D, D-L, L-polylactic acid invested with hyaluronan (HY). The cartilage region of the first device was a polyelectrolytic complex (PEC) hydrogel of HY and chitosan. In the second device the cartilage region consisted of type I collagen scaffold. Eighteen rabbits were implanted bilaterally with a device, or underwent defect creation with no implant. At 24 weeks, regenerated tissues were evaluated grossly, histologically and via immunostaining for type II collagen. RESULTS: PEC devices induced a significantly better repair than untreated shams. Collagen devices resulted in a quality of repair close to that of the PEC group, although its mean repair score (19.0+/-4.2) did not differ significantly from that of the PEC group (20.4+/-3.7) or the shams (16.5+/-6.3). The percentage of hyaline-appearing cartilage in the repair was highest with collagen implants, while the degree of bonding of repair to the host, structural integrity of the neocartilage, and reconstitution of the subchondral bone was greatest with PEC devices. Cartilage in both device-treated sites stained positive for type II collagen and GAG. CONCLUSIONS: Both implants are capable of maintaining hyaline-appearing tissue at 24 weeks. The physicochemical region between the cartilage and bone compartments makes these devices well suited for delivery of different growth factors or drugs in each compartment, or different doses of the same factor. It also renders these devices excellent vehicles for chondrocyte or stem cell transplantation

PURPOSE: To examine the incidence of benign and malignant eyelid lesions and conjunctival tumors. SUBJECTS AND METHODS: One-hundred-and twenty-eight cases (131 eyes) which were treated during the period from January 1990 to February 2004 were histopathologically diagnosed for eyelid or conjunctival tumors (87 cases of eyelid tumors and 41 cases of conjunctival tumors) in retrospective evaluations. The incidence of benign or malignant lesions, the pathological classification, age, sex, and clinical diagnostic accuracy were all investigated. RESULTS: Sixty-four (73%) of the tumors were found to be benign eyelid tumors. The common benign eyelid tumors were 14 nevocellular nevi, 9 seborrheic keratosis, 7 epidermoid cysts, and 6 papillomas. Twenty-four (27%) eyelid tumors were malignant. These included 9 basal cell carcinomas, 9 sebaceous gland carcinomas, 4 malignant lymphomas, and 2 metastatic tumors. Thirty-four (79%) conjunctival tumors were benign, and the common benign conjunctival tumors were 9 nevocellular nevi and 7 papillomas. Nine (21%) conjunctival tumors were malignant, comprising 7 malignant lymphomas and 2 squamous cell carcinomas. The mean ages of malignant eyelid and conjunctival tumor patients were significantly older than those of benign tumor patients. Clinical accuracy in predicting basal cell carcinoma and sebaceous gland carcinoma was 11.1% and 44.4%, respectively. CONCLUSIONS: Approximately 70 approximately 80% of all eyelid and conjunctival tumors are benign. Clinicians should suspect that the lesions are malignant when seeing elderly patients with eyelid or conjunctival tumors. Excised eyelid lesions should be submitted for histopathologic confirmation because there are some cases where clinical diagnosis does not match pathological diagnosis.