Altered executive control network resting-state connectivity in social anxiety disorder

Objectives: Research into the neural basis of social anxiety disorder (SAD) suggests alterations in prefrontal networks, which may in turn disrupt regulation of the limbic system. Better understanding of the disturbed interface between these networks may improve current pathogenic models of this disorder. Methods: Applying group independent component analysis (ICA) to recordings of fMRI resting-state, connectivity in the executive control network was studied in 18 patients with SAD and 15 age- and sex-matched healthy controls. Results: Results revealed a dissociation within the left executive control network, with SAD patients showing decreased connectivity of the orbitofrontal gyrus and increased connectivity of the middle frontal gyrus compared to healthy controls. In a subsequent seed-based functional connectivity analysis, patients with SAD displayed increased connectivity between the left orbitofrontal gyrus and the left amygdala. Conclusions: Findings suggest that hypo-connectivity in the executive control network and hyper-connectivity between the orbitofrontal cortex and the amygdala may reflect a disturbance in the balance between top-down and bottom-up control processes, potentially contributing to the development of SAD.     

POLD1 Germline Mutations in Patients Initially Diagnosed with Werner Syndrome

Segmental progeroid syndromes are rare, heterogeneous disorders characterized by signs of premature aging affecting more than one tissue or organ. A prototypic example is the Werner syndrome (WS), caused by biallelic germline mutations in the Werner helicase gene (WRN). While heterozygous lamin A/C (LMNA) mutations are found in a few nonclassical cases of WS, another 10%–15% of patients initially diagnosed with WS do not have mutations in WRN or LMNA. Germline POLD1 mutations were recently reported in five patients with another segmental progeroid disorder: mandibular hypoplasia, deafness, progeroid features syndrome. Here, we describe eight additional patients with heterozygous POLD1 mutations, thereby substantially expanding the characterization of this new example of segmental progeroid disorders. First, we identified POLD1 mutations in patients initially diagnosed with WS. Second, we describe POLD1 mutation carriers without clinically relevant hearing impairment or mandibular underdevelopment, both previously thought to represent obligate diagnostic features. These patients also exhibit a lower incidence of metabolic abnormalities and joint contractures. Third, we document postnatal short stature and premature greying/loss of hair in POLD1 mutation carriers. We conclude that POLD1 germline mutations can result in a variably expressed and probably underdiagnosed segmental progeroid syndrome.     

Pharmacokinetics of quinacrine in the treatment of prion disease

Background  

Prion diseases are caused by the accumulation of an aberrantly folded isoform of the prion protein, designated PrP^Sc. In a cell-based assay, quinacrine inhibits the conversion of normal host prion protein (PrP^C) to PrP^Sc at a half-maximal concentration of 300 nM. While these data suggest that quinacrine may be beneficial in the treatment of prion disease, its penetration into brain tissue has not been extensively studied. If quinacrine penetrates brain tissue in concentrations exceeding that demonstrated for in vitro inhibition of PrP^Sc, it may be useful in the treatment of prion disease.     

A mutagenesis study of a catalytic antibody.

We have generated seven site-specific mutations in the genes encoding the variable region of the heavy chain domain (VH) of the phosphocholine-binding antibody S107. S107 is a member of a family of well-characterized highly homologous antibodies that bind phosphorylcholine mono- and diesters. Two of these antibodies, MOPC-167 and T15, have previously been shown to catalyze the hydrolysis of 4-nitrophenyl N-trimethylammonioethyl carbonate. Two conserved heavy-chain residues, Tyr-33 and Arg-52, were postulated to be involved in binding and hydrolysis of 4-nitrophenylcholine carbonate esters. To more precisely define the catalytic roles of these residues, three Arg-52 mutants (R52K, R52Q, R52C) and four Tyr-33 mutants (Y33H, Y33F, Y33E, Y33D) of antibody S107 were generated. The genes encoding the VH binding domain of S107 were inserted into plasmid pUC-fl, and in vitro mutagenesis was performed. The wild-type and mutant S107 antibodies were expressed in P-3X63-Ag8.653 (P-3) myeloma cells by using a modified SV2 shuttle vector. The catalytic properties of wild-type antibody S107 are similar to those of the phosphocholine-specific antibody T15, which has the same VH protein sequence. In general, mutations at Tyr-33 had little effect on catalytic activity, whereas mutations at Arg-52 that result in loss of the positively charged side chain significantly lower the catalytic activity of S107. One mutant, Y33H, catalyzed the hydrolysis of 4-nitrophenyl N-trimethylammonioethyl carbonate with a kcat of 5.7 min-1 and a Km of 1.6 mM at pH 7.5. These results not only demonstrate the importance of electrostatic interactions in catalysis by antibody S107 but also show that catalytic side chains can be introduced into antibodies to enhance their catalytic efficiency.     

Limulus antilipopolysaccharide factor protects rabbits from meningococcal endotoxin shock.

Limulus antilipopolysaccharide factor (LALF), an 11.8-kDa peptide isolated from amebocytes of Limulus polyphemus, neutralizes meningococcal lipooligosaccharide (LOS)-induced gelation of limulus amebocyte lysate. Rabbits challenged with an LD90 of LOS (10 micrograms/kg) premixed with LALF in vitro (n = 10) had significantly higher mean arterial pressure, arterial pH, serum bicarbonate concentrations, and survival (90% vs. 8%, P = .005) than did rabbits challenged with LOS alone. Relative to untreated controls, rabbits pretreated with LALF intravenously (iv) at 1.2 mg/kg (n = 21) also had significant improvements in physiologic measurements and higher survival (52% vs. 8%, P = .003). Even when LALF (1.2 mg/kg iv) was given 1/2 h after LOS challenge, animals showed significant improvements in physiologic measurements and survival (33% vs. 8% in untreated controls P = .028). LALF-treated animals also had significantly lower circulating endotoxin activity and tumor necrosis factor concentrations. Thus, LALF attenuates the toxic effects of meningococcal LOS in rabbits even when administered after LOS challenge and deserves further evaluation as a potential therapeutic agent for treating gram-negative septic shock.     

Garnet sand reveals rock recycling processes in the youngest exhumed high- and ultrahigh-pressure terrane on Earth

Rock recycling within the forearcs of subduction zones involves subduction of sediments and hydrated lithosphere into the upper mantle, exhumation of rocks to the surface, and erosion to form new sediment. The compositions of, and inclusions within detrital minerals revealed by electron microprobe analysis and Raman spectroscopy preserve petrogenetic clues that can be related to transit through the rock cycle. We report the discovery of the ultrahigh-pressure (UHP) indicator mineral coesite as inclusions in detrital garnet from a modern placer deposit in the actively exhuming Late Miocene–Recent high- and ultrahigh-pressure ((U)HP) metamorphic terrane of eastern Papua New Guinea. Garnet compositions indicate the coesite-bearing detrital garnets are sourced from felsic protoliths. Carbonate, graphite, and CO₂ inclusions also provide observational constraints for geochemical cycling of carbon and volatiles during subduction. Additional discoveries include polyphase inclusions of metastable polymorphs of SiO₂ (cristobalite) and K-feldspar (kokchetavite) that we interpret as rapidly cooled former melt inclusions. Application of elastic thermobarometry on coexisting quartz and zircon inclusions in six detrital garnets indicates elastic equilibration during exhumation at granulite and amphibolite facies conditions. The garnet placer deposit preserves a record of the complete rock cycle, operative on <10-My geologic timescales, including subduction of sedimentary protoliths to UHP conditions, rapid exhumation, surface uplift, and erosion. Detrital garnet geochemistry and inclusion suites from both modern sediments and stratigraphic sections can be used to decipher the petrologic evolution of plate boundary zones and reveal recycling processes throughout Earth’s history.

Throughout Earth’s history, igneous, metamorphic, and sedimentary rocks have been recycled from the surface to upper mantle depths and subsequently returned as a result of tectonic and sedimentary processes operating within and at the surface of lithospheric plates. In active plate boundary zones, where most igneous and metamorphic rocks form, the rock cycle involves localized lithospheric deformation, which exhumes rocks to the Earth’s surface. When rock exhumation occurs at plate tectonic rates (centimeters year⁻¹) (1, 2), high- and ultrahigh-pressure ((U)HP) metamorphic rocks containing hydrous mineral assemblages, trapped volatiles, and atmospheric gases (3, 4) may be returned from upper mantle depths to the surface in the forearcs of subduction zones. Mechanically strong host minerals, such as garnet, zircon, and clinopyroxene, and their nondecrepitated mineral inclusions have played a key role in the identification of (U)HP metamorphic rocks and conditions of metamorphism (5). After rocks are exposed at the surface, weathering processes erode (U)HP rocks to create sediment that is transported from source to sink, retaining evidence of metamorphic conditions in the compositions, and inclusions trapped within detrital mineral grains (6, 7). Garnet is a common mineral in metamorphic and igneous rocks of the upper mantle and crust that can survive transit through the rock cycle (8). Garnet is stable over a large range of pressure–temperature (P-T) conditions in many bulk rock compositions; commonly entraps and preserves (meta-)stable mineral inclusions; and is relatively resistant to chemical alteration during erosion, transport, and deposition. As a result, detrital garnet compositions (9) and their mineral inclusions (10), identified in the heavy-mineral fractions of sediments and sedimentary rocks, provide constraints on the conditions of garnet growth in source rocks.The youngest known (U)HP terrane on Earth is actively exhuming in eastern Papua New Guinea within the obliquely convergent Australian (AUS)–Pacific (PAC) plate boundary zone (11) (Fig. 1). The Papuan (U)HP terrane formed when a rifted fragment of the Cretaceous AUS continental margin was subducted at the Aure–Pocklington trough (12, 13). In the D’Entrecasteaux Islands of the Woodlark Rift, Late Miocene–Recent metamorphic core complexes, composed of (U)HP metamorphic rocks (i.e., lower plate), have been exhumed to the surface at centimeters year⁻¹ rates from beneath upper plate rocks composed of oceanic lithosphere (14, 15). Direct evidence for ultrahigh-pressure (UHP) metamorphism has only been identified in one sample at one outcrop in the D’Entrecasteaux Islands (16). The coesite eclogite at this locality is interpreted to have formed ∼8 Ma when a partial mantle melt intruded subducted continental lithosphere at UHP conditions (4, 12, 17). Since the discovery of coesite eclogite, attempts to find additional mineral evidence for UHP metamorphism from outcrop samples, including from felsic lithologies, have been unsuccessful. However, intermediate-depth earthquakes in proximity to exhumed coesite eclogite indicate active seismicity in the tectonic setting where UHP exhumation is ongoing (18).Open in a separate windowFig. 1.(A) Tectonic and geologic setting of the (U)HP terrane in the Woodlark Rift of eastern Papua New Guinea. The (U)HP terrane is located within the larger obliquely convergent AUS–PAC plate boundary zone and formed when an AUS-derived continental fragment was subducted northward beneath oceanic lithosphere at the Aure–Pocklington trough. (U)HP rocks are found in the lower plates of metamorphic core complexes in the D’Entrecasteaux Islands (Goodenough Island [GI], Fergusson Island [FI], and Normanby Island [NI]), within the Woodlark Rift (WR). Low-grade metamorphic rocks of the accretionary wedge are exposed in the Louisiade Archipelago (LA). Global Positioning System model vectors (orange arrows) are shown for present-day Woodlark (WLK) plate motion relative to the AUS plate; AUS–WLK rotation poles for 3.6 to 0.5 Ma and 0.5 Ma to present are also indicated (50). Modified from ref. 19. (B) Geologic map of the D’Entrecasteaux Islands with the garnet placer deposit, coesite eclogite (UHP), and active CO₂ seep localities indicated. Base maps were made with GeoMapApp (51).Goodenough Island, the westernmost metamorphic core complex within the subaerial portion of the Woodlark Rift, forms a prominent topographic dome where garnet-bearing eclogite and felsic to intermediate gneisses comprise a core zone and carapace shear zones (Fig. 1). Basement rocks include eclogite, granulite, and amphibolite with abundant evidence for in situ partial melts and granodioritic intrusions (Figs. 1 and ​and2).2). The dome is flanked by seismically active normal faults (18). Pliocene–Pleistocene surface uplift (19) and emergence of the islands above sea level led to erosion of the (U)HP terrane and deposition of Holocene colluvium and alluvium including the sampled garnet placer deposit, formed from erosion of garnet-bearing protoliths (Figs. 1B and ​and2E).2E). Electron microprobe analysis and Raman spectroscopy of detrital garnets revealed evidence for rock recycling processes in the youngest exhumed (U)HP terrane on Earth where exhumation occurred during the same subduction cycle that produced the (U)HP rocks.Open in a separate windowFig. 2.Schematic figure illustrating rock (re-)cycling in the eastern Papuan (U)HP terrane where rifting of a subduction complex has exhumed (U)HP rocks since ∼8 Ma (i.e., negligible petrologic lag times). (A) Early–Middle Miocene northward subduction of an AUS continental fragment formed low-grade metamorphic rocks of the accretionary wedge [Calvados Schist, Louisiade archipelago (13)]. (B) (U)HP metamorphism of basalts and felsic protoliths formed eclogite in quartzofeldspathic host gneisses now exposed in the core zone, including in the catchment areas nearby the placer deposit locality. Coesite eclogite (UHP locality in Fig. 1B) formed at ∼8 Ma, whereas eclogite in the catchment area (in the photo) is as young as 2 Ma (31, 52). (C) Partial melting of gneisses in the garnet placer catchment area (in the photo), intrusion of igneous rocks, and volcanism have occurred since ∼4 Ma (14, 53). (D) Surface uplift to form the D’Entrecasteaux Islands since the Quaternary (19). (E) Rock erosion, transportation, and deposition of sediment to form a garnet-rich placer deposit. Schematic P-T path (details are presented in Fig. 5) illustrates conditions associated with metamorphic, igneous, and sedimentary rock formation and recycling in the Papuan (U)HP terrane. Geothermal gradients and reaction curves indicated (quartz [qz], coesite [coe], graphite [gra], and diamond [dia]).     

Two new sickle cell syndromes: HbS, Hb Camden, and alpha-thalassemia; and HbS in combination with Hb Tacoma

Hemoglobin variants having electrophoretic mobility more rapid than that of HbA were identified in combination with sickle hemoglobin in two patients at the Cook County Hospital. Neither individual had symptomatic hematologic disease. In one patient, the rapidly migrating hemoglobin had the amino acid substitution characteristic of Hb Tacoma (beta-40 arg leads to ser), a mildly unstable variant. In the other patient, Hb Camden (beta-131 gln leads to glu) was identified, and the hematologic findings also indicated that he has alpha-thalassemia trait. In the patient with HbS-Camden--alpha-thalassemia, globin synthesis was unbalanced (alpha/beta 0.66), and HbS represented only 19.5% of the total hemoglobin. The latter finding suggests that under conditions of limited alpha-chain availability beta Camden may combine with alpha subunits at least as efficiently as does betaA. HbS represented 56% of the hemoglobin of the patient with HbS Tacoma, although the rate of synthesis of beta Tacoma by her reticulocytes was consistently greater than that of betaS. A time-course synthesis study demonstrated a progressive increase in the specific activity of beta Tacoma in relation to that of betaS, suggesting that the unstable beta- chains of Hb Tacoma underwent selective intracellular degradation. This process appears to explain the disparity between the rates of synthesis of the two beta chains and the relative representation of HbS and Hb Tacoma in the patient's erythrocytes.     

Evidence against a requisite role for defective virus in the establishment of persistent hepadnavirus infections.

The factors involved in the establishment of persistent hepadnavirus infection are poorly understood. Recent findings demonstrate that the sequence of the genome of hepatitis B virus (HBV) is variable in infected individuals and that, in some cases, virus mutants predominate. Our objectives in the present study were to analyze the variability of woodchuck hepatitis virus (WHV) genomes in an infected animal and to determine whether sequence heterogeneity played a critical role in the ability of WHV to induce chronic infection. We cloned and determined the complete nucleotide sequence of three supercoiled genomes from an animal that became infected after inoculation with a standardized WHV serum pool (i.e., the WHV7 virus pool). We found that there were four nucleotide substitutions among the three genome sequences as well as a 73-nucleotide deletion in one of the recombinants. DNA transfection experiments revealed that only one of the three recombinants was capable of independent replication. These data suggest that a significant proportion of replicative templates in woodchucks that are infected with WHV are defective virus genomes. Next, we compared the outcome of acute infection after inoculation with a serum pool containing a uniform population of replication competent virus (i.e., the WHV7R pool) with a serum pool composed of WHV genomes of variable sequence. The WHV7R serum pool originated from a woodchuck that became a chronic carrier after in vivo transfection of the liver with the infectious WHV7 recombinant. Neonatal woodchucks were inoculated with 5 x 10(6) WHV genome equivalents of either the WHV7 pool or the WHV7R pool. All animals in the study became acutely infected with WHV. Of the animals infected with the WHV7 serum pool, 65% became chronic carriers, while 80% of the animals infected with the WHV7R serum pool developed chronic infection. Thus, infection of woodchucks with a serum pool containing defective virus resulted in a rate of chronic WHV infection that was similar to, or even lower than, a rate from a pool containing only wild-type virus. This suggests that the presence of defective virus in the inoculum is not a prerequisite for the establishment of persistent hepadnavirus infections.