Site-specific de-N-glycosylation of CD44 can activate hyaluronan binding, and CD44 activation states show distinct threshold densities for hyaluronan binding

CD44 is a cell surface receptor for the glycosaminoglycan hyaluronan (HA). Not all CD44-positive cells bind HA, and binding ability is strictly regulated. Three different HA binding states have been defined: inactive, inducible (by certain CD44-specific monoclonal antibodies), and constitutively active. The observation that sets of genetically related cell lines representing different HA binding states showed correlated differences in N-glycosylation of CD44, and that inhibition of N-glycosylation enhanced HA binding (Lesley et al., J. Exp. Med., 182: 431-437, 1995) led us to examine directly whether specific N-glycosylation site modifications were involved in regulating the HA binding function. CD44-negative, -active, and inducible cell lines were stably transfected with mutant constructs in which each of the five N-glycosylation sites of murine CD44 had been separately inactivated. Ability to bind soluble HA was examined over a range of CD44 expression levels. For the active cell line, AKR1, transfectants for all N-glycosylation mutants bound HA as well as did transfectants for wild type CD44. No inhibitory effects of inactivating specific N-glycosylation sites were observed. HA binding was activated when two of the mutant constructs were transfected into a novel CD44-negative inducible cell line. Inactivation of N-glycosylation sites at residues 25 or 120 converted the inducible cell line to constitutively active, whereas inactivation of other sites had little or no effect. Fusion proteins secreted from inactive, inducible, or active cell lines were purified, bound to beads, and assayed for HA binding activity by flow cytometric analysis. Fusion proteins derived from inactive, inducible, and constitutively active cells exhibited three distinguishable "threshold" densities required for HA binding ability. The results imply that the CD44 molecules produced in cells in these three activation states have intrinsic differences in HA binding function. Treatment of the fusion proteins with neuraminidase altered the HA binding state, and glycosylation mutations that affected the phenotype of the inducible cell line lowered the threshold required for HA binding of CD44-immunoglobulin fusion proteins derived from the inducible cell line. Thus, alterations of glycosylation of CD44 itself can affect HA binding ability as manifested by a change in HA binding state.     

Alterations in anterior hypothalamic vasopressin, but not serotonin, correlate with the temporal onset of aggressive behavior during adolescent anabolic-androgenic steroid exposure in hamsters (Mesocricetus auratus).

In hamsters (Mesocricetus auratus), anabolic-androgenic steroid (AAS) exposure during adolescence facilitates offensive aggression that is correlated with the enhanced development of the arginine vasopressin (AVP) neural system and reduced development of the serotonin (5-HT) neural system in the anterior hypothalamus (AH). This study examined the temporal onset of these effects by measuring aggression and AH AVP and 5-HT during progressively shorter periods of AAS exposure during adolescent development. The authors tested adolescent hamsters that received AAS for 3, 7, 14, or 28 days for offensive aggression and then examined the hamsters for AVP/5-HT afferent innervation to the AH using immunohistochemistry. While reductions in AH 5-HT afferent innervation were detectable by 7 days of AAS exposure, no concomitant increases in offensive aggression were observed compared to oil-treated littermates. In contrast, by Day 14 of AAS treatment, AH AVP and offensive aggression were significantly higher than oil-treated controls. These data indicate that relatively short-term adolescent AAS exposure alters aggression and AH 5-HT and AVP development, yet only alterations in AH AVP development correlate with temporal onset of the aggressive behavioral phenotype during adolescent AAS exposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigating the effects of reduced size on the properties of ferroelectrics

A series of experiments has been undertaken to understand more about the fundamental origin of the thickness-induced permittivity collapse often observed in conventional thin film ferroelectric heterostructures. The various experiments are discussed, highlighting the eventual need to examine permittivity collapse in thin film single crystal material. It has been seen that dielectric collapse is not a direct consequence of reduced size, and neither is it a consequence of unavoidable physics associated with the ferroelectric-electrode boundary. Research on three-dimensional shape-constrained ferroelectrics, emphasizing self-assembled structures based on nanoporous alumina templates and on FIB-milled single crystals, is also presented, and appears to represent an exciting area for ongoing research.     

Plasticity in anterior hypothalamic vasopressin correlates with aggression during anabolic-androgenic steroid withdrawal in hamsters.

In hamsters, adolescent anabolic-androgenic steroid (AAS) exposure facilitates offensive aggression, in part by altering the development and activity of anterior hypothalamic arginine vasopressin (AH-AVP). This study assessed whether these effects were lasting by examining aggression and AH-AVP during AAS withdrawal. Adolescent hamsters administered AAS were tested as adults for aggression at 1, 4, 11, 18, or 25 days of withdrawal, sacrificed the following day, and examined for AH-AVP afferent innervation using immunohistochemistry. Through Day 12 of withdrawal, aggression and AVP were significantly higher in AAS-treated hamsters than in controls. These differences were no longer observable by Day 19 of withdrawal, at which point the behavior and neurobiology of AAS-treated hamsters reverted to that observed in controls. These data indicate that adolescent AAS exposure has short-term, reversible effects on both aggression and AH-AVP, correlating AH-AVP with the aggressive/nonaggressive behavioral phenotype during AAS withdrawal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Toward a conceptualization of the family's adaptation to a member's head injury: A critique of developmental stage models.

Developmental stage models proposed to conceptualize the family's adaptation to a head-injured member are critiqued. In general, hypotheses about stages have not been subjected to empirical investigation. Due to conceptual problems in the models, the stages do not meet the criteria of legitimate explanatory constructs. In their present form, stages proposed by different models are, at best, of heuristic value. It is argued that principles from S. Minuchin's (1974) structural family therapy model may be integrated with the stage model approach in a manner that helps resolve some conceptual problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ScFv multimers of the anti-neuraminidase antibody NC10: shortening of the linker in single-chain Fv fragment assembled in VL to VH orientation drives the formation of dimers, trimers, tetramers and higher molecular mass multimers

Synthetic genes encoding single-chain variable fragments (scFvs)of NC10 anti-neuraminidase antibody were constructed by joiningthe V_L and V_H domains with linkers of fifteen, five, four, three,two, one and zero residues. These V_L–V_H constructs wereexpressed in Escherichia coli and the resulting proteins werecharacterized and compared with the previously characterizedNC10 scFv proteins assembled in V_H–V_L orientation. Size-exclusionchromatography and electron microscope images of complexes formedbetween various NC10 scFvs and anti-idiotype Fab' were usedto analyse the oligomeric status of these scFvs. The resultshowed that as the linker length between V_L and V_H was reduced,different patterns of oligomerization were observed comparedwith those with V_H–V_L isomers. As was the case for V_H–V_Lorientation, the scFv-15 V_L–V_H protein existed mainlyas a monomer whereas dimer (diabody) was a predominant conformationfor the scFv-5, scFv-4 and scFv-3 V_L–V_H proteins. In contrastto the V_H–V_L isomer, direct ligation of V_L to V_H led tothe formation of predominantly a tetramer (tetrabody) ratherthan to an expected trimer (triabody). Furthermore, the transitionbetween dimers and higher order oligomers was not as distinctas for V_H–V_L. Thus reducing the linker length in V_L–V_Hfrom three to two residues did not precisely dictate a transitionbetween dimers and tetramers. Instead, two-residue as well asone-residue linked scFvs formed a mixture of dimers, trimersand tetramers.