Effects of vagus nerve stimulation on extinction of conditioned fear and post-traumatic stress disorder symptoms in rats.

Exposure-based therapies help patients with post-traumatic stress disorder (PTSD) to extinguish conditioned fear of trauma reminders. However, controlled laboratory studies indicate that PTSD patients do not extinguish conditioned fear as well as healthy controls, and exposure therapy has high failure and dropout rates. The present study examined whether vagus nerve stimulation (VNS) augments extinction of conditioned fear and attenuates PTSD-like symptoms in an animal model of PTSD. To model PTSD, rats were subjected to a single prolonged stress (SPS) protocol, which consisted of restraint, forced swim, loss of consciousness, and 1 week of social isolation. Like PTSD patients, rats subjected to SPS show impaired extinction of conditioned fear. The SPS procedure was followed, 1 week later, by auditory fear conditioning (AFC) and extinction. VNS or sham stimulation was administered during half of the extinction days, and was paired with presentations of the conditioned stimulus. One week after completion of extinction training, rats were given a battery of behavioral tests to assess anxiety, arousal and avoidance. Results indicated that rats given SPS 1 week prior to AFC (PTSD model) failed to extinguish the freezing response after eleven consecutive days of extinction. Administration of VNS reversed the extinction impairment and attenuated reinstatement of the conditioned fear response. Delivery of VNS during extinction also eliminated the PTSD-like symptoms, such as anxiety, hyperarousal and social avoidance for more than 1 week after VNS treatment. These results provide evidence that extinction paired with VNS treatment can lead to remission of fear and improvements in PTSD-like symptoms. Taken together, these findings suggest that VNS may be an effective adjunct to exposure therapy for the treatment of PTSD.

Enamel Bond Strength of New Universal Adhesive Bonding Agents.

PURPOSE: Universal bonding agents have been introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinician's preference. The purpose of this study was to evaluate the shear bond strength (SBS) of composite to enamel using universal adhesives compared to a self-etch adhesive when applied in self-etch and etch-and-rinse modes over time. METHODS AND MATERIALS: Extracted human third molars were used to create 120 enamel specimens. The specimens were ground flat and randomly divided into three groups: two universal adhesives and one self-etch adhesive. Each group was then subdivided, with half the specimens bonded in self-etch mode and half in etch-and-rinse mode. The adhesives were applied as per manufacturers' instructions, and composite was bonded using a standardized mold and cured incrementally. The groups were further divided into two subgroups with 10 specimens each. One subgroup was stored for 24 hours and the second for six months in 37°C distilled water and tested in shear. Failure mode was also determined for each specimen. RESULTS: A three-way analysis of variance (ANOVA) found a significant difference between groups based on bonding agent (p<0.001) and surface treatment (p<0.001) but not on time (p=0.943), with no significant interaction (p>0.05). Clearfil SE in etch-and-rinse and self-etch modes had more mixed fractures than either universal adhesive in either mode. CONCLUSIONS: Etching enamel significantly increased the SBS of composite to enamel. Clearfil SE had significantly greater bond strength to enamel than either universal adhesive, which were not significantly different from each other.

Sonic hedgehog is required for cardiac outflow tract and neural crest cell development.

The Hedgehog signaling pathway is critical for a significant number of developmental patterning events. In this study, we focus on the defects in pharyngeal arch and cardiovascular patterning present in Sonic hedgehog (Shh) null mouse embryos. Our data indicate that, in the absence of Shh, there is general failure of the pharyngeal arch development leading to cardiac and craniofacial defects. The cardiac phenotype results from arch artery and outflow tract patterning defects, as well as abnormal development of migratory neural crest cells (NCCs). The constellation of cardiovascular defects resembles a severe form of the human birth defect syndrome tetralogy of Fallot with complete pulmonary artery atresia. Previous studies have demonstrated a role for Shh in NCC survival and proliferation at later stages of development. Our data suggest that SHH signaling does not act directly on NCCs as a survival factor, but rather acts to restrict the domains that NCCs can populate during early stages (e8.5-10.5) of cardiovascular and craniofacial development.

Pup exposure differentially enhances foraging ability in primiparous and nulliparous rats.

The role of maternal experience (i.e., pregnancy and pup exposure) on rats' performance in a foraging task was assessed. Primiparous (P) and nulliparous (N) animals were either exposed to pups for 21 days (+) or received no pup exposure (-). Following habituation trials, all animals were tested in spatial and cued versions of the dry land maze (DLM) for three days (three trials per day). In the spatial DLM, the presence of pups decreased latencies in both N and P groups in Trial 5 and P+ rats exhibited shorter latencies to baited food wells than P- animals on Trial 6. In the subsequent probe trial, P+ animals spent significantly more time in proximity to the previously baited well than P- rats. Pups enhanced performance of both P+ and N+ groups in trial 6 of the cued test. Thus, in the spatial task, the individual components of the maternal experience (e.g., pregnancy, parturition, lactation, and pup exposure) converge to produce behavioral modifications in the DLM spatial and probe tasks that enable the female to care for her offspring, in this case, by enhancing foraging behavior. Further, in one trial of each version of the task, pup exposure enhanced performance in N animals suggesting that, in isolation, pup exposure may be a more important influence on ancillary maternal behavior than the pregnancy itself.

Syntheses and structural characterizations of sheet- and column-like lanthanide-transition metal arrays: the effect of hydrogen bonding on the structure when K(+) is replaced by [NH4]+.

Sheet- and column-like cyanide bridged lanthanide-transition metal arrays were synthesized through metathesis reactions between anhydrous LnCl(3) (Ln = Eu, Yb) and A(2)[M(CN)(4)] (A = K(+), NH(4)(+); M = Ni, Pt) in a 1:2 molar ratio in DMF (DMF = N,N-dimethylformamide) solution. Single-crystal X-ray analysis revealed that complexes of formula [K(DMF)(7)Ln[M(CN)(4)](2)](infinity) (Ln = Eu, M = Ni, 1; Ln = Yb, M = Pt, 2) consist of infinite layers of neutral, puckered sheets that contain hexagonal rings of composition [(DMF)(10)Ln(2)[M(CN)(4)](3)](6) with interstitial (DMF)(4)K(2)[M(CN)(4)] units located between the layers. The sheet structure is generated through the repeating (DMF)(10)Ln(2)[M(CN)(4)](3) unit with trans cyanide ligands in [M(CN)(4)](2)(-) serving as bridges. The column-like complex [(NH(4))(DMF)(4)Yb[Pt(CN)(4)](2)](infinity), 3, is formed when NH(4)(+) replaces K(+). It consists of infinite, negatively charged, square, parallel columns bundled through N-H...NC hydrogen bonds between NH(4)(+) and terminal CN from the columns. Cis cyanide ligands in [Pt(CN)(4)](2)(-) units serve as bridges. Complex 3 is the first known example where Ln(III) centers are coordinated to four [M(CN)(4)](2)(-) units. Bicapped (square face) trigonal prismatic coordination geometries were observed for Ln(III) centers in 1 and 2. Square antiprismatic geometry for Yb(III) centers are observed in 3. Crystal data for 1: triclinic space group P1, a = 8.797(2) A, b = 15.621(3) A, c = 17.973(6) A, alpha = 105.48(2) degrees, beta = 98.60(2) degrees, gamma = 98.15(2) degrees, Z = 2. Crystal data for 2: triclinic space group P1, a = 8.825(1) A, b = 15.673(1) A, c = 17.946(1) A, alpha = 105.46(2) degrees, beta = 99.10(1) degrees, gamma = 98.59(1) degrees, Z = 2. Crystal data for 3: monoclinic space group P2(1)/c, a = 9.032(1) A, b = 29.062(1) A, c = 15.316(1) A, beta = 94.51(1) degrees, Z = 2.

Cyanide-bridged lanthanide(III)-transition metal extended arrays: interconversion of one-dimensional arrays from single-strand (type A) to double-strand (type B) structures. Complexes of a new type of single-strand array (type C).

A series of one-dimensional arrays of lanthanide-transition metal complexes has been prepared and characterized. These complexes, [(DMF)(10)Ln(2)[Ni(CN)(4)](3)](infinity), crystallize as linear single-strand arrays (structural type A) (Ln = Sm, 1a; Eu, 2a) or double-strand arrays (structural type B) (Ln = Sm, 1b; Eu, 2b) depending upon the conditions chosen, and they are interconvertible. The single-strand type A structure can be converted to the double-strand type B structure. When the 1b and 2b type B crystals are completely dissolved in DMF, their infrared spectra are identical to the infrared spectra of 1a and 2a type A crystals dissolved in DMF. These solutions produce type A crystals initially. It is believed that formation of the type A structure is kinetically favored while the type B structure is thermodynamically favored for lanthanide-nickel complexes 1 and 2. On the other hand the complex [(DMF)(10)Y(2)[Pd(CN)(4)](3)](infinity), 3, appears to crystallize only as the double-strand array (type B). The complexes [(DMF)(12)Ce(2)[Ni(CN)(4)](3)](infinity), 4, and [(DMF)(12)Ce(2)[Pd(CN)(4)](3)](infinity), 5, crystallize as a new type of single-strand array (structural type C). This structural type is a zigzag chain array. Crystal data for 1a: triclinic space group P1, a = 10.442(5) A, b = 10.923(2) A, c = 15.168(3) A, alpha = 74.02(2) degrees, beta = 83.81(3) degrees, gamma = 82.91(4) degrees, Z = 2. Crystal data for 1b: triclinic space group P1, a = 9.129(2) A, b = 11.286(6) A, c = 16.276(7) A, alpha = 81.40(4) degrees, beta = 77.41(3) degrees, gamma = 83.02(3) degrees, Z = 2. Crystal data for 2a: triclinic space group P1, a = 10.467(1) A, b = 10.923(1) A, c = 15.123(1) A, alpha = 74.24(1) degrees, beta = 83.61(1) degrees, gamma = 83.13(1) degrees, Z = 2. Crystal data for 2b: triclinic space group P1, a = 9.128(1) A, b = 11.271(1) A, c = 16.227(6) A, alpha = 81.36(2) degrees, beta = 77.43(2) degrees, gamma = 82.99(1) degrees, Z = 2. Crystal data for 3: triclinic space group P1, a = 9.251(3) A, b = 11.193(4) A, c = 16.388(4) A, alpha = 81.46(2) degrees, beta = 77.18(2) degrees, gamma = 83.24(3) degrees, Z = 2. Crystal data for 4: triclinic space group P1, a = 11.279(1) A, b = 12.504(1) A, c = 13.887(1) A, alpha = 98.68(1) degrees, beta = 108.85(1) degrees, gamma = 101.75(1) degrees, Z = 2. Crystal data for 5: triclinic space group P1, a = 11.388(3) A, b = 12.614(5) A, c = 13.965(4) A, alpha = 97.67(3) degrees, beta = 109.01(2) degrees, gamma = 101.93(2) degrees, Z = 2.

Differential requirement for SLP-76 domains in T cell development and function.

The hematopoietic cell-specific adaptor protein, SLP-76, is critical for T cell development and mature T cell receptor (TCR) signaling; however, the structural requirements of SLP-76 for mediating thymopoiesis and mature T cell function remain largely unknown. In this study, transgenic mice were generated to examine the requirements for specific domains of SLP-76 in thymocytes and peripheral T cells in vivo. Examination of mice expressing various mutants of SLP-76 on the null background demonstrates a differential requirement for specific domains of SLP-76 in thymocytes and T cells and provides new insight into the molecular mechanisms underlying SLP-76 function.

Conditional inactivation of Fgf4 reveals complexity of signalling during limb bud development.

Development of the vertebrate limb bud depends on reciprocal interactions between the zone of polarizing activity (ZPA) and the apical ectodermal ridge (AER). Sonic hedgehog (SHH) and fibroblast growth factors (FGFs) are key signalling molecules produced in the ZPA and AER, respectively. Experiments in chicks suggested that SHH expression in the ZPA is maintained by FGF4 expression in the AER, and vice versa, providing a molecular mechanism for coordinating the activities of these two signalling centres. This SHH/FGF4 feedback loop model is supported by genetic evidence showing that Fgf4 expression is not maintained in Shh-/- mouse limbs. We report here that Shh expression is maintained and limb formation is normal when Fgf4 is inactivated in mouse limbs, thus contradicting the model. We also found that maintenance of Fgf9 and Fgf17 expression is dependent on Shh, whereas Fgf8 expression is not. We discuss a model in which no individual Fgf expressed in the AER (AER-Fgf) is solely necessary to maintain Shh expression, but, instead, the combined activities of two or more AER-Fgfs function in a positive feedback loop with Shh to control limb development.

Synthesis and characterization of sulfide, sulfide-sulfonium, and bissulfide derivatives of [B12H12]2-. Additivity of Me2S and MeS- substituent effects in 11B NMR spectra of disubstituted icosahedral boron clusters.

The 1,2-, 1,7-, and 1,12-isomers of (Me2S)2B12H10 (O, M, and P) react with potassium phthalimide in DMF or EtSNa in CH3CN/EtOH upon reflux producing the corresponding isomers of [(MeS)(Me2S)B12H10]- (O1-, M1-, P1-). If excess of either nucleophile is used, [Me2SB12H11]- (1) and O, M, P can be converted into dianions [MeSB12H11]2- (2) and [(MeS)2B12H10]2- (O2-, M2-, P2-). The use of EtSNa is recommended since it facilitates the isolation of products compared to the potassium phthalimide method. When 1 or O, M, P are treated with an excess of an alkali metal (Na, K) in liquid ammonia at -40 degrees C, sulfide 2 or bissulfide dianions O2-, M2-, P2- are obtained cleanly and almost instantly. While both the nucleophilic substitution and alkali metal reduction methods are useful for the synthesis of dianions 2, O2-, M2-, and P2-, only the former method is suitable for the synthesis of the sulfide-sulfonium anions O1-, M1-, P1-. The analysis of the 11B NMR spectra of 1, O, M, P and anions derived from them demonstrated that the spectra of the disubstituted species can be predicted qualitatively, keeping in mind the simple substituent effects obtained from the spectra of monosubstituted anions 1 and 2. Some evidence is found for small partial double bond character of the B-SMe bonds in anions. [MePPh3]+ salts of [MeSB12H11]2- (2) and [1-(MeS)-7-(Me2S)B12H10]- (M1-) are structurally characterized by single-crystal X-ray diffraction analysis. Crystal data: [MePPh3]2[MeSB12H11], P2(1) (No. 4), a = 9.243(1) A, b = 18.272(1) A, c = 12.548(1) A, beta = 103.17(1) degrees, Z = 2; [MePPh3][1-(MeS)-7-(Me2S)B12H10], P1 (No. 2), a = 9.278(2) A, b = 12.003(5) A, c = 14.819(7) A, alpha = 112.18(4) degrees, beta = 105.61(3) degrees, gamma = 92.91(3) degrees, Z = 2.

A new type of hexaosmium boride cluster, H3Os6(CO)16B, that does not conform to electron counting rules.

A new type of hexaosmium boride cluster, H3Os6(CO)16B, was produced in the thermolysis of H3Os3(CO)9(BCO). This complex is an 86 valence electron cluster, but the Os6 framework does not possess one of the geometries previously observed for Os6 clusters that have 86 valence electrons. [HOs6(CO)18]- and [Os6(CO)18]2- have octahedral frameworks while that of H2Os6(CO)18 is a face-capped square pyramid. The Os6 framework of H3Os6(CO)16B can be viewed as being derived from a pentagonal bipyramid that is missing one equatorial vertex. It contains an interior boron atom. Alternatively, it can be viewed like the 84 valence cluster Os6(CO)18 as either a bicapped tetrahedron, with a boron atom residing on the edge of the tetrahedron that is common to the capped faces, or a face-capped trigonal bipyramid, with the boron atom on an equatorial edge of the bipyramid that is also an edge of the capped face. H3Os6(CO)16B was characterized by 1H, and 11B, 13C NMR, IR, and mass spectroscopies and single-crystal X-ray diffraction analysis. The molecular structure was determined from two separate crystals. The analysis of each crystal yielded virtually identical structures, but their volumes differed by 36 A3 due to differences in packing in the unit cell. Data for crystal I of H3Os6(CO)16B: monoclinic P2(1/n), a = 9.954(2) A, b = 15.780(4) A, c = 16.448(3) A, beta = 91.07(1) degrees, Z = 4. Data for crystal II of H3Os6(CO)16B: monoclinic P2(1/n), a = 9.927(2) A, beta = 16.623(2) A, b = 16.0233(10) A, beta = 97.78(1) degrees, Z = 4.

First year after head and neck cancer: quality of life.

PURPOSE: Treatment regimens for head and neck cancer patients profoundly affect several quality-of-life domains. Rehabilitative needs have been identified through cross-sectional analyses; however, few studies have prospectively assessed quality of life, included assessment of psychosocial variables, and identified predictors of long-term follow-up. PARTICIPANTS AND METHODS: The present study addresses these limitations through a prospective assessment of 105 patients with a newly diagnosed first primary squamous cell carcinoma of the oral cavity, pharynx, or larynx. Participants were enrolled onto a larger randomized controlled trial comparing a provider-delivered smoking cessation intervention with a usual-care-advice control condition. Participants completed a battery of self-report measures after diagnosis and before treatment and additional quality-of-life instruments at 1 and 12 months after initial smoking cessation advice. RESULTS: Participants displayed improvements at 12 months in functional status (P = .006) and in the areas of eating, diet, and speech; however, the latter three represent areas of continued dysfunction, and the changes were not statistically significant. Despite these improvements, patients reported a decline in certain quality-of-life domains, including marital (P = .002) and sexual functioning (P = .017), as well as an increase in alcohol use (P < .001). Predictors of quality of life at 12 months included treatment type, the Vigor subscale of the Profile of Mood States instrument, and quality-of-life scores obtained 1 month after initial smoking cessation advice. CONCLUSION: Results reinforce the need for rehabilitation management through the integration of psychologic and behavioral interventions in medical follow-up.

Differences in left-right axis pathways in mouse and chick: functions of FGF8 and SHH.

A molecular pathway leading to left-right asymmetry in the chick embryo has been described, in which FGF8 is a right determinant and Sonic Hedgehog a left determinant. Here evidence is presented that the Fgf8 and Sonic Hedgehog genes are required for left-right axis determination in the mouse embryo, but that they have different functions from those previously reported in the chick. In the mouse FGF8 is a left determinant and Sonic Hedgehog is required to prevent left determinants from being expressed on the right.

Targeted disruption of Fgf8 causes failure of cell migration in the gastrulating mouse embryo.

Fgf8 and Fgf4 encode FGF family members that are coexpressed in the primitive streak of the gastrulating mouse embryo. We have analyzed the phenotype of Fgf8(-/-) embryos and discovered that they fail to express Fgf4 in the streak. In the absence of both FGF8 and FGF4, epiblast cells move into the streak and undergo an epithelial-to-mesenchymal transition, but most cells then fail to move away from the streak. As a consequence, no embryonic mesoderm- or endoderm-derived tissues develop, although extraembryonic tissues form. Patterning of the prospective neuroectoderm is greatly perturbed in the mutant embryos. Anterior neuroectoderm markers are widely expressed, at least in part because the anterior visceral endoderm, which provides signals that regulate their expression, is not displaced proximally in the absence of definitive endoderm. Posterior neuroectoderm markers are not expressed, presumably because there is neither mesendoderm underlying the prospective neuroectoderm nor a morphologically normal node to provide the inductive signals necessary for their expression. This study identifies Fgf8 as a gene essential for gastrulation and shows that signaling via FGF8 and/or FGF4 is required for cell migration away from the primitive streak.

Scanning acoustic microscopy study of titanium-ceramic interface of dental restorations.

Failures that occur in titanium-ceramic restorations are of concern in clinical dentistry. The purpose of this study was to nondestructively characterize the internal cracks and nonadherent defects at the titanium-porcelain interface using scanning acoustic microscopy. Titanium samples coated with porcelain without a bonding agent, with sputter coated palladium or chromium as an oxygen diffusion barrier on the titanium, and with the use of a porcelain bonding agent (control group) were compared. The scanning acoustic microscopy analyses were correlated with four-point bending test results. The group that was initially coated with palladium had fewer interfacial defects and a higher load to failure than the control group, and the group that did not contain the bonding agent had a higher void area and a lower load to failure than the control group. The use of chromium produced no differences from the control group. Samples after a four-point bending test were also analyzed by scanning electron microscopy. The scanning electron microscopy was not able to characterize interfacial defects at the fractured titanium-ceramic interface for some of the samples. The validity of nondestructive analysis at the Ti-ceramic interface using scanning acoustic microscopy was demonstrated in this study.

An Fgf8 mutant allelic series generated by Cre- and Flp-mediated recombination.

We describe a strategy for generating an allelic series of mutations at a given locus that requires the production of only one targetted mouse line. The 'allelogenic' mouse line we produced carries a hypomorphic allele of Fgf8, which can be converted to a null allele by mating to cre transgenic animals. The hypomorphic allele can also be reverted to wild-type by mating the allelogenic mice to flp transgenic animals, thereby generating a mouse line suitable for Cre-induced tissue-specific knockout experiments. Analysis of embryos carrying different combinations of these alleles revealed requirements for Fgf8 gene function during gastrulation, as well as cardiac, craniofacial, forebrain, midbrain and cerebellar development.

Bacillaene, a novel inhibitor of procaryotic protein synthesis produced by Bacillus subtilis: production, taxonomy, isolation, physico-chemical characterization and biological activity.

Bacillaene, a novel polyene antibiotic, was discovered and isolated from fermentation broths of a strain of Bacillus subtilis. The novel antibiotic has a nominal molecular weight of 580 and an empirical formula of C35H48O7. Bacillaene is active against a broad spectrum of bacteria in agar-plate diffusion assays. Studies in vitro indicate that the antibiotic inhibits prokaryotic protein synthesis but not eukaryotic protein synthesis. Cell survival studies performed with strains of Escherichia coli indicate that the antibiotic is a bacteriostatic agent.