Hominin taxic diversity: Fact or fantasy? Wood, Bernard; K. Boyle, Eve
American journal of physical anthropology,
01/2016, Letnik:
159, Številka:
S61
Journal Article
Abstract Preterm birth (PTB) is the leading cause of childhood mortality in children under 5 and accounts for approximately 11% of births worldwide. Premature babies are at risk of a number of health ...complications, notably cerebral palsy, but also respiratory and gastrointestinal disorders. Preterm deliveries can be medically indicated/elective procedures or they can occur spontaneously. Spontaneous PTB is commonly associated with intrauterine infection/inflammation. The presence of inflammatory mediators in utero has been associated with fetal injury, particularly affecting the fetal lungs and brain. This review will outline (i) the role of inflammation in term and PTB, (ii) the effect infection/inflammation has on fetal development and (iii) recent strategies to target PTB. Further research is urgently required to develop effective methods for the prevention and treatment of PTB and above all, to reduce fetal injury.
Key points
The superficial spinal dorsal horn contains a heterogeneous population of neurons that process sensory inputs.
Information on the properties of excitatory interneurons in this region is ...limited. As calretinin is a protein thought to be restricted to an excitatory population in this region, the aim of this study was to characterize calretinin‐expressing neurons.
Most calretinin cells (85%) exhibited large A‐type potassium currents and delayed firing action potential discharge, and received strong excitatory synaptic input, whereas the remainder exhibited hyperpolarization‐activated cation currents and low threshold T‐type calcium currents, and tonic‐ or initial bursting firing patterns, and received weak excitatory synaptic input. These respective features are consistent with properties of excitatory and inhibitory interneuron populations in this region of the spinal cord.
Our findings have resolved a previously unidentified population of inhibitory interneurons. Furthermore, the contrasting excitability patterns of excitatory and inhibitory calretinin‐expressing neurons suggest that they play distinct roles in spinal sensory processing circuits.
Neurons in the superficial dorsal horn (SDH) of the spinal cord play an important role in nociceptive, thermal, itch and light touch sensations. Excitatory interneurons comprise ∼65% of all SDH neurons but surprisingly few studies have investigated their role in spinal sensory processing. Here we use a transgenic mouse to study putative excitatory SDH neurons that express the calcium binding protein calretinin (CR). Our immunocytochemical, morphological and electrophysiological analysis identified two distinct populations of CR‐expressing neurons, which we termed ‘Typical’ and ‘Atypical’. Typical CR‐expressing neurons comprised ∼85% of the population and exhibited characteristic excitatory interneuron properties including delayed firing discharge, large rapid A‐type potassium currents, and central, radial or vertical cell morphologies. Atypical neurons exhibited properties consistent with inhibitory interneurons, including tonic firing or initial bursting discharge, Ih currents, and islet cell morphology. Although both Typical and Atypical CR‐expressing neurons responded to noxious peripheral stimulation, the excitatory drive onto Typical CR‐expressing neurons was much stronger. Furthermore, Atypical CR‐expressing cells comprise at least two functionally distinct subpopulations based on their responsiveness to noxious peripheral stimulation and neurochemical profile. Together our data suggest CR expression is not restricted to excitatory neurons in the SDH. Under normal conditions, the contribution of ‘Typical’ excitatory CR‐expressing neurons to overall SDH excitability may be limited by the presence of A‐type potassium currents, which limit the effectiveness of their strong excitatory input. Their contribution may, however, be increased in pathological situations where A‐type potassium currents are decreased. By contrast, ‘Atypical’ inhibitory neurons with their excitable phenotype but weak excitatory input may be more easily recruited during increased peripheral stimulation.
Key points
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Perception of normal bodily sensations relies on the precise regulation of sensory information entering the dorsal horn of the spinal cord.
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Inhibitory, axoaxonic, synapses provide a ...mechanism for this regulation, but the source of these important inhibitory connections remains to be elucidated.
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This study shows that a subpopulation of spinal interneurons that expresses parvalbumin and have specific morphological, connectivity and functional characteristics are a likely source of the inhibitory inputs that selectivity regulate non‐noxious tactile input in the spinal cord.
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Our findings suggest that a loss of normal function in parvalbumin positive dorsal horn neurons may result in the development of tactile allodynia, where non‐painful stimuli gain the capacity to evoke the sensation of pain.
Axo‐axonic synapses on the central terminals of primary afferent fibres modulate sensory input and are the anatomical correlate of presynaptic inhibition. Although several classes of primary afferents are under such inhibitory control, the origin of these presynaptic inputs in the dorsal horn is unknown. Here, we characterize the neurochemical, anatomical and electrophysiological properties of parvalbumin (PV)‐expressing cells in wild‐type and transgenic mice where enhanced green fluorescent protein (eGFP) is expressed under the PV promoter. We show that most PV cells have either islet or central cell‐like morphology, receive inputs from myelinated primary afferent fibres and are concentrated in laminae II inner and III. We also show that inhibitory PV terminals in lamina II inner selectively target the central terminals of myelinated afferents (∼80% of 935 PVeGFP boutons) and form axo‐axonic synapses (∼75% of 71 synapses from PV boutons). Targeted whole‐cell patch‐clamp recordings from PVeGFP positive cells in laminae II and III showed action potential discharge was restricted to the tonic firing and initial bursting patterns (67% and 33% respectively; n= 18), and virtually all express Ih subthreshold voltage‐gated currents (94%; n= 18). These neurons show higher rheobase current than non‐eGFP cells but respond with high frequency action potential discharge upon activation. Together, our findings show that PV neurons in laminae II and III are a likely source of inhibitory presynaptic input on to myelinated primary afferents. Consequently PV cells are ideally placed to play an important role in the development of central sensitization and tactile allodynia.
Purpose of Review
The associated patient morbidity and resource-intensive nature of managing surgical site infections (SSI) has focused attention toward not only improving treatment protocols but ...also enhancing preventative measures. The purpose of this review was to summarize the relevant updated CDC guidelines for the prevention of SSI that were released in 2017. The CDC recommends the integration of the guidelines for improvement in quality metrics, reportable outcomes, and patient safety.
Recent Findings
The updated guidelines include generalized recommendations for parenteral antimicrobial prophylaxis, non-parenteral antimicrobial prophylaxis, glycemic control, normothermia, oxygenation, and antiseptic prophylaxis. The arthroplasty section includes recommendations for blood transfusion, systemic immunosuppressive therapy, and antibiotics during drain use. There was low-quality evidence precluding recommendations for preoperative intra-articular corticosteroid injections, orthopedic surgical space suits, and biofilm management.
Summary
The recommendations provided throughout this review, including more recent guidelines from other organizations such as the AAOS and ACR, should assist clinicians in developing and/or refining surgical site prevention protocols for their patients undergoing total joint arthroplasty procedures.
Sheet metal formability is assessed in terms of the Forming Limit Diagram (FLD) for magnesium alloys with Hexagonal Close Packed (HCP) crystallographic structure. All simulations are based on the ...recently developed elastic–visco-plastic self-consistent (EVPSC) model and the classical Taylor model, in conjunction with the M–K approach. The role of crystal plasticity models and the effects of basal texture on formability of magnesium alloy AZ31B sheet are studied numerically. It is observed that formability in HCP polycrystalline materials is very sensitive to the intensity of the basal texture. The path-dependency of formability is examined based on different non-proportional loading histories, which are combinations of two linear strain paths. It is found that while the FLD in strain space is very sensitive to strain path changes, the Forming Limit Stress Diagram (FLSD) in stress space is much less path-dependent. It is suggested that the FLSD is much more favourable than the FLD in representing forming limits in the numerical simulation of sheet metal forming processes. The numerical results are found to be in good qualitative agreement with experimental observations.
Biological cells deform on a nanometer scale when their transmembrane voltage changes, an effect that has been visualized during the action potential using quantitative phase imaging. Similar changes ...in the optical path length have been observed in photoreceptor outer segments after a flash stimulus via phase-resolved optical coherence tomography. These optoretinograms reveal a fast, millisecond-scale contraction of the outer segments by tens of nanometers, followed by a slow (hundreds of milliseconds) elongation reaching hundreds of nanometers. Ultrafast measurements of the contractile response using line-field phase-resolved optical coherence tomography show a logarithmic increase in amplitude and a decreasing time to peak with increasing stimulus intensity. We present a model that relates the early receptor potential to these deformations based on the voltage-dependent membrane tension—the mechanism observed earlier in neurons and other electrogenic cells. The early receptor potential is caused by conformational changes in opsins after photoisomerization, resulting in the fractional shift of the charge across the disk membrane. Lateral repulsion of the ions on both sides of the membrane affects its surface tension and leads to its lateral expansion. Because the volume of the disks does not change on a millisecond timescale, their lateral expansion leads to an axial contraction of the outer segment. With increasing stimulus intensity and the resulting tension, the area expansion coefficient of the disk membrane also increases as thermally induced fluctuations are pulled flat, resisting further expansion. This leads to the logarithmic saturation observed in measurements as well as the peak shift in time. This imaging technique therefore relates the structural changes in the photoreceptor to the underlying neurological function of transducing light into electrical signals. Such label-free optical monitoring of neural activity using fast interferometry may be applicable not only to optoretinography but also to neuroscience in general.
Local antibiotic delivery systems with differing chemical and mechanical properties have been developed to assist in the management of osteomyelitis. We investigated the bone conductive and ...resorptive capabilities of a calcium phosphate-calcium sulfate (CaP/CaS) composite compared with commercially available polymethylmethacrylate (PMMA). In addition, we compared the in vivo preventative and treatment efficacies of both biomaterials in a proven osteomyelitis model.
Sixty-four, male Sprague-Dawley rats were inoculated with 10 μl of 1.5 x 108 CFU/ml of Staphylococcus aureus in a surgically drilled defect in the right proximal tibia. Infected animals were randomly allocated into prevention and treatment groups with 32 rats each. In the prevention group, the defect was filled with a plug containing either PMMA or CaP/CaS immediately after the inoculation. In the treatment group, the infected defects were irrigated, debrided, and filled with either a PMMA or CaP/CaS plug. Both CaP/CaS and PMMA were impregnated with 10% weight of vancomycin. Rats were sacrificed 6 weeks after cement insertion. Infection was detected by bacterial culture and histological analysis. Bone formation in the defect was assessed with micro-computed tomography and histology.
No bacteria were detected in any group. Both the prevention and treatment groups using CaP/CaS had significantly more bone volume fraction, bone area, and cartilage area than the PMMA groups.
When loaded with 10% of vancomycin, CaP/CaS and PMMA have the same efficacy for treatment and prevention of osteomyelitis. CaP/CaS enhances bone defect healing through improved bone remodeling in our osteomyelitis rat model.
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