Genetic evidence that brain-derived neurotrophic factor mediates competitive interactions between individual cortical neurons.

Brain-derived neurotrophic factor (BDNF) is a secreted protein important for development and function of neocortical circuitry. Although it is well established that BDNF contributes to the sculpting of dendrite structure and modulation of synapse strength, the range and directionality of BDNF signaling underlying these functions are incompletely understood. To gain insights into the role of BDNF at the level of individual neurons, we tested the cell-autonomous requirements for Bdnf in visual cortical layer 2/3 neurons. We found that the number of functional Bdnf alleles a neuron carries relative to the prevailing genotype determines its density of dendritic spines, the structures at which most excitatory synapses are made. This requirement for Bdnf exists both during postnatal development and in adulthood, suggesting that the amount of BDNF a neuron is capable of producing determines its success in ongoing competition in the environment of the neocortex. Our results suggest that BDNF may perform a long-sought function for a secreted growth factor in mediating the competitive events that shape individual neurons and their circuits.

Flexor digitorum superficialis repair outside the A2 pulley after zone II laceration: gliding and bowstringing.

PURPOSE: To evaluate the changes in maximum flexion angle, gliding coefficient, and bowstringing after a combined repair of both flexor tendons with the flexor digitorum superficialis (FDS) rerouted outside the A2 pulley in cadaveric hands. METHODS: We performed 4 different repairs on cadaveric hands, with each repair tested on 9 unique digits. In total, 12 cadaveric hands and 36 digits were used. The thumb and little finger were removed from each hand and excluded from testing. Group 1 was sham surgery. Group 2 combined flexor digitorum profundus (FDP) and FDS laceration and repair with both slips of the FDS repaired inside the A2 pulley. Group 3 was FDP repair with one slip of the FDS repaired inside A2 and the other slip left unrepaired. Group 4 was FDP repair with both slips of the FDS rerouted and repaired outside the A2 pulley. Maximum flexion angle, gliding coefficient, and bowstringing were measured in simulated active digital motion for each group. RESULTS: Rerouting and repairing the FDS outside the A2 pulley (group 4) significantly lowered gliding coefficient compared with repairs with both slips inside A2, with values similar to sham surgery. We observed no significant differences in maximum flexion angle among the 4 groups. Increased bowstringing was observed with both slips of the FDS repaired and rerouted outside the A2 pulley. CONCLUSIONS: In this cadaveric model, repair of both slips of the FDS outside the A2 pulley improved the gliding coefficient relative to repair within the A2 pulley, which suggests decreased resistance to finger flexion. Repair of the FDS outside the A2 pulley led to a slight increase in bowstringing of the FDS tendon. CLINICAL RELEVANCE: We describe a technique for managing combined laceration of the FDP and FDS tendons that improves gliding function and merits consideration.

The Effect of the Epitendinous Suture on Gliding in a Cadaveric Model of Zone II Flexor Tendon Repair.

PURPOSE: We hypothesized that increasing core sutures (4-6) may be preferable in terms of gliding coefficient (GC) measurements when compared with adding an epitendinous suture to zone II flexor tendon repairs. We hypothesized that the inclusion of epitendinous suture in 2 standard repairs would contribute negatively to the GC of the repaired tendon. METHODS: Nineteen fresh-frozen cadaveric fingers were used for testing. We compared a control group (dissected digits without repair) and 4-strand or 6-strand core tendon repairs with and without epitendinous suture. Arc of motion was driven by direct loading, and digital images were acquired and analyzed. Outcomes were defined as the difference in GC between the native uninjured and the repaired state at each load. A linear mixed-model analysis was performed with comparisons between repairs to evaluate the statistically relevant differences between groups. RESULTS: The test of fixed effects in the linear model revealed that repair type and the use of epitendinous suture significantly affected the change in GC. The addition of an epitendinous suture produced a significant decrement in gliding regardless of repair type. CONCLUSIONS: There was significant improvement in GC with the omission of the epitendinous suture in both repair types (4- or 6-strand). CLINICAL RELEVANCE: The epitendinous suture used in this model resulted in poorer gliding of the repair, which may correspond with an expected increase in catching or triggering.

Scapular dyskinesis following displaced fractures of the middle clavicle.

PURPOSE: To evaluate the rate of scapular dyskinesis and resulting patient outcomes after treatment of displaced midshaft clavicle fractures. METHODS: Skeletally mature patients with isolated, displaced midshaft clavicle fractures treated with or without surgery over a 16-month period were recruited. The minimum length of follow-up at study examination was 12 months. Patient outcomes were documented using the SICK (scapular malposition, inferomedial border prominence, coracoid pain and malposition, and dyskinesis of scapular movement) Scapula Rating Scale, the Simple Shoulder Test, 3 visual analog scales (VAS) for pain, and shoulder range-of-motion and strength measurements. Of the 32 eligible patients, 24 (75%) were successfully recruited. RESULTS: The mean participant age was 46 ± 17 years, with a mean length of follow-up at study evaluation of 1.7 ± 1 years. Surgical fixation was performed in 12 patients (50%). Scapular dyskinesis was present in 37.5% of patients (n = 9). Patients with scapular dyskinesis had worse SICK scapula scores (5.8 ± 2.2 vs 3.1 ± 2.4, P = .01), worse Simple Shoulder Test scores (10.5 ± 1.6 vs 11.7 ± 0.8, P = .029), higher maximum VAS pain scores (4.1 ± 3.1 vs 0.97 ± 1.2, P = .002), and worse average VAS pain scores in the week before the examination (2.7 ± 2.5 vs 0.2 ± 0.4, P < .001) compared with patients without scapular dyskinesis. Range of motion and abduction strength were similar between the groups. Scapular dyskinesis developed in 1 patient treated with surgery (8% [1 of 12]) compared with 8 patients treated nonoperatively (67% [8 of 12]) (P = .009). CONCLUSIONS: Scapular dyskinesis is common after displaced middle-third clavicle fractures, and these patients have more pain and worse functional outcomes compared with patients without scapular dyskinesis. Surgical treatment may reduce a patient's risk of scapular dyskinesis developing and improve short-term outcomes.

In(x)Ga(1-x)As nanowire growth on graphene: van der Waals epitaxy induced phase segregation.

The growth of high-density arrays of vertically oriented, single crystalline InAs NWs on graphene surfaces are realized through the van der Waals (vdW) epitaxy mechanism by metalorganic chemical vapor deposition (MOCVD). However, the growth of InGaAs NWs on graphene results in spontaneous phase separation starting from the beginning of growth, yielding a well-defined InAs-In(x)Ga(1-x)As (0.2 < x < 1) core-shell structure. The core-shell structure then terminates abruptly after about 2 µm in height, and axial growth of uniform composition In(x)Ga(1-x)As takes place without a change in the NW diameter. The In(x)Ga(1-x)As shell composition changes as a function of indium flow, but the core and shell thicknesses and the onset of nonsegregated In(x)Ga(1-x)As axial segment are independent of indium composition. In contrast, no InGaAs phase segregation has been observed when growing on MoS2, another two-dimensional (2D) layered material, or via the Au-assisted vapor-liquid-solid (VLS) mechanism on graphene. This spontaneous phase segregation phenomenon is elucidated as a special case of van der Waals epitaxy on 2D sheets. Considering the near lattice matched registry between InAs and graphene, InGaAs is forced to self-organize into InAs core and InGaAs shell segments since the lack of dangling bonds on graphene does not allow strain sharing through elastic deformation between InGaAs and graphene.

Cell cycle progression and de novo centriole assembly after centrosomal removal in untransformed human cells.

How centrosome removal or perturbations of centrosomal proteins leads to G1 arrest in untransformed mammalian cells has been a mystery. We use microsurgery and laser ablation to remove the centrosome from two types of normal human cells. First, we find that the cells assemble centrioles de novo after centrosome removal; thus, this phenomenon is not restricted to transformed cells. Second, normal cells can progress through G1 in its entirety without centrioles. Therefore, the centrosome is not a necessary, integral part of the mechanisms that drive the cell cycle through G1 into S phase. Third, we provide evidence that centrosome loss is, functionally, a stress that can act additively with other stresses to arrest cells in G1 in a p38-dependent fashion.

Cutaneous malignancies of the upper extremity.

Cutaneous malignancies are the most common primary malignancies of the hand. The hand surgeon may be the first physician to see these patients or may have the patients referred to them because of expertise in this anatomical region. This article reviews diagnosis and treatment, including margin of resection and need for sentinel lymph node biopsy, for the 3 most common cutaneous malignancies: basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.

Prolonged, Low-Level Exposure to the Marine Toxin, Domoic Acid, and Measures of Neurotoxicity in Nonhuman Primates.

BACKGROUND: The excitotoxic molecule, domoic acid (DA), is a marine algal toxin known to induce overt hippocampal neurotoxicity. Recent experimental and epidemiological studies suggest adverse neurological effects at exposure levels near the current regulatory limit (20 ppm, ∼0.075-0.1mg/kg). At these levels, cognitive effects occur in the absence of acute symptoms or evidence of neuronal death. OBJECTIVES: This study aimed to identify adverse effects on the nervous system from prolonged, dietary DA exposure in adult, female Macaca fascicularis monkeys. METHODS: Monkeys were orally exposed to 0, 0.075, and 0.15mg/kg per day for an average of 14 months. Clinical blood counts, chemistry, and cytokine levels were analyzed in the blood. In-life magnetic resonance (MR) imaging assessed volumetric and tractography differences in and between the hippocampus and thalamus. Histology of neurons and glia in the fornix, fimbria, internal capsule, thalamus, and hippocampus was evaluated. Hippocampal RNA sequencing was used to identify differentially expressed genes. Enrichment of gene networks for neuronal health, excitotoxicity, inflammation/glia, and myelin were assessed with Gene Set Enrichment Analysis. RESULTS: Clinical blood counts, chemistry, and cytokine levels were not altered with DA exposure in nonhuman primates. Transcriptome analysis of the hippocampus yielded 748 differentially expressed genes (fold change≥1.5; p≤0.05), reflecting differences in a broad molecular profile of intermediate early genes (e.g., FOS, EGR) and genes related to myelin networks in DA animals. Between exposed and control animals, MR imaging showed comparable connectivity of the hippocampus and thalamus and histology showed no evidence of hypomyelination. Histological examination of the thalamus showed a larger microglia soma size and an extension of cell processes, but suggestions of a GFAP+astrocyte response showed no indication of astrocyte hypertrophy. DISCUSSION: In the absence of overt hippocampal excitotoxicity, chronic exposure of Macaca fascicularis monkeys to environmentally relevant levels of DA suggested a subtle shift in the molecular profile of the hippocampus and the microglia phenotype in the thalamus that was possibly reflective of an adaptive response due to prolonged DA exposure. https://doi.org/10.1289/EHP10923.

The de novo centriole assembly pathway in HeLa cells: cell cycle progression and centriole assembly/maturation.

It has been reported that nontransformed mammalian cells become arrested during G1 in the absence of centrioles (Hinchcliffe, E., F. Miller, M. Cham, A. Khodjakov, and G. Sluder. 2001. Science. 291:1547-1550). Here, we show that removal of resident centrioles (by laser ablation or needle microsurgery) does not impede cell cycle progression in HeLa cells. HeLa cells born without centrosomes, later, assemble a variable number of centrioles de novo. Centriole assembly begins with the formation of small centrin aggregates that appear during the S phase. These, initially amorphous "precentrioles" become morphologically recognizable centrioles before mitosis. De novo-assembled centrioles mature (i.e., gain abilities to organize microtubules and replicate) in the next cell cycle. This maturation is not simply a time-dependent phenomenon, because de novo-formed centrioles do not mature if they are assembled in S phase-arrested cells. By selectively ablating only one centriole at a time, we find that the presence of a single centriole inhibits the assembly of additional centrioles, indicating that centrioles have an activity that suppresses the de novo pathway.

Modulation of ionizing radiation-induced apoptosis by bantam microRNA in Drosophila.

In Drosophila, heterozygosity in the pro-apoptotic gene hid significantly reduces apoptosis that is induced by ionizing radiation (IR). Therefore, mechanisms that regulate Hid levels can potentially contribute to life-or-death decision of an irradiated cell. 3'UTR of hid mRNA contains 5 potential binding sites for bantam microRNA. Ectopic expression of ban attenuated apoptosis that results from ectopic expression of hid but the significance of this regulation under physiological conditions remained to be investigated. We report here that ban is needed to limit IR-induced apoptosis in larval imaginal discs. Using tubulin-EGFP ban sensors with ban consensus sequences in the 3'UTR, we find that EGFP decreases following IR, indicating that IR activates ban. Likewise, a tubulin-EGFP reporter with hid-3'UTR is repressed in irradiated discs and this repression requires ban consensus sites in the hid 3'UTR. ban mutant larvae show increased sensitivity to killing by IR, which is suppressed by a mutation in hid. These results can fit into a model in which IR activates ban and ban represses hid to limit IR-induced apoptosis. miRNAs have been shown previously to be induced by radiation but this is the first report that a miRNA is functionally important for radiation responses.

Evidence for persistence of the SHIV reservoir early after MHC haploidentical hematopoietic stem cell transplantation.

Allogeneic transplantation (allo-HCT) has led to the cure of HIV in one individual, raising the question of whether transplantation can eradicate the HIV reservoir. To test this, we here present a model of allo-HCT in SHIV-infected, cART-suppressed nonhuman primates. We infect rhesus macaques with SHIV-1157ipd3N4, suppress them with cART, then transplant them using MHC-haploidentical allogeneic donors during continuous cART. Transplant results in ~100% myeloid donor chimerism, and up to 100% T-cell chimerism. Between 9 and 47 days post-transplant, terminal analysis shows that while cell-associated SHIV DNA levels are reduced in the blood and in lymphoid organs post-transplant, the SHIV reservoir persists in multiple organs, including the brain. Sorting of donor-vs.-recipient cells reveals that this reservoir resides in recipient cells. Moreover, tetramer analysis indicates a lack of virus-specific donor immunity post-transplant during continuous cART. These results suggest that early post-transplant, allo-HCT is insufficient for recipient reservoir eradication despite high-level donor chimerism and GVHD.

The effects of local bFGF release and uniaxial strain on cellular adaptation and gene expression in a 3D environment: implications for ligament tissue engineering.

The objectives of this investigation were (1) to characterize the growth factor release profile of a basic fibroblast growth factor (bFGF)-coated three-dimensional (3D) polymer scaffold under static and cyclically strained conditions, and (2) to delineate the individual and collective contributions of locally released bFGF and mechanical strain on cellular morphology and gene expression in this 3D system. Scaffolds were treated with I(125)-bFGF and subjected to mechanical strain or maintained in a static environment and the media sampled for factor release over a period of 6 days. Over the first 10 hours, a burst release of 25% of the incorporated growth factor into the surrounding media was noted. At 24 hours, approximately 40% of the bFGF was released into the media, after which steady state was achieved and minimal subsequent release was noted. Mechanical stimulation had no effect on growth factor release from the scaffold in this system. To test the concerted effects of bFGF and mechanical stimulation on bone marrow stromal cells (BMSCs), scaffolds were loaded with 0, 100, or 500 ng of bFGF, seeded with cells, and subjected to mechanical strain or maintained in a static environment. Scaffolds were harvested at 1, 7, and 21 days for RT-PCR and histomorphometry. All scaffolds subjected to growth factor and/or mechanical stimulation demonstrated cellular adherence and spreading at 21 days. Conversely, in the absence of both bFGF and mechanical stimulation, cells demonstrated minimal cytoplasmic spread. Moreover, at 21 days, cells subjected to both mechanical stimulation and bFGF (500 ng) demonstrated the highest upregulation of stress-resistive (collagen I, III) and stress-responsive proteins (tenascin-C). The effect of growth factor may be dose sensitive, however, as unstrained scaffolds treated with 100 ng of bFGF demonstrated upregulation of gene expression comparable to strained scaffolds treated with lower doses of bFGF (0 or 100 ng). In conclusion, results from this study suggest that the stimulatory effects of bFGF are dose sensitive and appear to be influenced by the addition of mechanical strain. The concurrent application of biochemical and mechanical stimuli may be important in promoting the adaptation of BMSCs and driving the transcription of genes essential for synthesis of a functional ligament replacement tissue.

Outcomes assessment of pediatric both-bone forearm fractures treated operatively.

This study assessed the outcome of pediatric both-bone forearm fractures treated with operative intervention. A retrospective review was conducted of 31 patients treated over a 40-month period. Fifteen patients were treated with flexible intramedullary nailing and 16 treated with open reduction and internal fixation. Average patient age was 11 years (range: 3.8-17.9 years). Operative indications included 2 open fractures and 29 fractures with unacceptable reductions. The intramedullary nailing group had 14 excellent results and 1 good result. The open reduction internal fixation group had 15 excellent results and 1 good result. Overall, 29 (93.5%) of 31 patients had excellent results. Two minor complications occurred in the intramedullary nailing group and none in the open reduction internal fixation group. Although operative intervention in pediatric both-bone forearm fractures is rarely indicated, when necessary, good results can be expected.

Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

High-speed analysis of residual solvents by flow-modulation gas chromatography.

High-speed gas chromatographic (GC) separation of residual solvents in pharmaceutical preparations, using a flow-modulation technique, is described. These volatile compounds are separated on a series-coupled (tandem) column ensemble consisting of a polyethylene glycol column and a trifluoropropylmethyl/dimethylpolysiloxane column. This column ensemble is operated in stop-flow mode to enhance, or "tune", the separation. A valve between the junction point of the tandem column ensemble and a source of carrier gas at a pressure above the GC inlet pressure is opened for intervals of 2-8 s. This stops or slightly reverses the flow of carrier gas in the first column. Stop-flow pulses are used to increase the separation of target analytes that overlap in the total ensemble chromatogram, compared to non-stop-flow, or conventional, operation. All 36 target compounds, based on ICH Classes I and II residual solvent lists, are resolved in 12 min using the stop-flow technique and a single chromatographic analysis.

Salmonella enterica infection stimulates macrophages to hemophagocytose.

UNLABELLED: Hemophagocytes are cells of the monocyte lineage that have engulfed erythrocytes and leukocytes. Hemophagocytes frequently accumulate in patients with severe acute bacterial infections, such as those caused by Salmonella enterica, Brucella abortus, and Mycobacterium tuberculosis. The relationship between hemophagocytosis and infection is not well understood. In the murine liver, S. enterica serovar Typhimurium resides within hemophagocytic macrophages containing leukocytes. Here we show that S. Typhimurium also resides within hemophagocytes containing erythrocytes. In cell culture, S. Typhimurium benefits from residence within hemophagocytes by accessing iron, but why macrophages hemophagocytose is unknown. We show that treatment of macrophages with a cocktail of the proinflammatory cytokine interferon gamma (IFN-γ) and lipopolysaccharide (LPS) stimulates engulfment of nonsenescent erythrocytes. Exposure of resting or IFN-γ-treated macrophages to live, but not to heat-killed, S. Typhimurium cells also stimulates erythrocyte engulfment. Single-cell analyses show that S. Typhimurium-infected macrophages are more likely to erythrophagocytose and that infected macrophages engulf more erythrocytes than uninfected macrophages within the same culture well. In addition, macrophages containing erythrocytes harbor more bacteria. However, S. Typhimurium does not promote macrophage engulfment of polystyrene beads, suggesting a role for a ligand on the target cell. Finally, neither of the two S. Typhimurium type 3 secretion systems, T3SS1 or T3SS2, is fully required for hemophagocytosis. These results indicate that infection of macrophages with live S. Typhimurium cells stimulates hemophagocytosis. IMPORTANCE: Macrophages are white blood cells (leukocytes) that engulf and destroy pathogens. Hemophagocytes, a subset of macrophages, are characteristic of severe acute infection in patients with, for instance, typhoid fever, brucellosis, tuberculosis, and leishmaniasis. Each of these diseases has the potential to become chronic. Hemophagocytes (blood-eating cells) engulf and degrade red and white blood cells for unknown reasons. The bacterial pathogen Salmonella acquires the essential nutrient iron from murine hemophagocytes. We report that Salmonella stimulates macrophages to engulf blood cells, indicating that cells of this bacterium actively promote the formation of a specialized cellular niche in which they can acquire nutrients, evade killing by the host immune system, and potentially transition to chronic infection.

Proximal humerus fractures with associated axillary artery injury.

Proximal humerus fractures have rarely been associated with injuries to the axillary artery. Most of the fractures described have been Neer 2-part surgical neck fractures with medialization of the shaft fragment and resultant laceration or thrombosis of the axillary artery. No intraoperative deaths have been reported. We present a series of 3 proximal humerus fractures, 2 of which are Neer 3- to 4-part anterior fracture dislocations, and associated axillary artery injury. There were 2 mortalities, 1 intraoperative. After a thorough review of the English literature, we identified an additional 11 cases of axillary artery injury associated with proximal humerus fracture. The purpose of this study was to heighten the clinical suspicion of this vascular injury in patients with proximal humerus fracture dislocations and surgical neck fractures with shaft medialization, as well as to review pathogenesis and guide management decisions.

The Effect of Pulley Reconstruction on Maximum Flexion, Bowstringing, and Gliding Coefficient in the Setting of Zone II Repair of FDS and FDP: a Cadaveric Investigation.

PURPOSE: The purpose of this experiment was to determine the effect of A2 pulley reconstruction on gliding coefficient (GC), bowstringing, and proximal interphalangeal (PIP) joint maximum flexion angle after zone II repair of flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) lacerations. METHODS: Fresh frozen cadaver forearms were mounted, and the wrist and MCP joints fixed. FDS and FDP tendons were dissected free, and sequential loads were applied while digital images were captured. The dissected digit with intact native A2 pulley, FDS, and FDP tendons was used as the control (group 1). Zone II lacerations followed by four-stranded repair of FDP plus epitendinous suture and repair of FDS were then performed, and the data recorded (group 2). A2 pulley excision and reconstruction with a loop of palmaris longus autograft was then completed and the specimens sequentially loaded and photographed (group 3). Using the digital images, GC, bowstringing, and maximum flexion angle were calculated. RESULTS: No difference in maximum flexion angle was observed across the three testing conditions. Zone II laceration and subsequent FDS and FDP tendon repair significantly increased the GC for group 2 specimens; however, pulley reconstruction alleviated some of this increase for group 3. Bowstringing was significantly greater after pulley reconstruction, with a mean increase of 1.9 mm at maximum flexion for group 3 specimens relative to group 1 controls. DISCUSSION: Strong flexor tendon repairs are needed to prevent gap formation and subsequent triggering; however, the increased bulk from these large repairs can itself produce deleterious triggering, as well as tendon abrasion. Pulley reconstruction, in the setting FDP and FDS repair (group 3), significantly reduced the GC relative to tendon repair alone (group 2). While bowstringing was significantly greater after pulley reconstruction (group 3), it averaged only 1.9 mm over group 1 specimens and did not compromise maximum flexion angle compared to the uninjured controls (group 1) or the isolated tendon repair digits (group 2).