Rates of Epidural Blood Patch following Lumbar Puncture Comparing Atraumatic versus Bevel-Tip Needles Stratified for Body Mass Index.

BACKGROUND AND PURPOSE: Postdural puncture headache, a known complication of lumbar puncture, typically resolves with conservative management. Symptoms persist in a minority of patients, necessitating an epidural blood patch. One method of decreasing rates of postdural puncture headache is using atraumatic, pencil-point needles rather than bevel-tip needles. To the best of our knowledge, this is the first study comparing epidural blood patch rates between pencil- and bevel-tip needles with a subgroup analysis based on body mass index. MATERIALS AND METHODS: This single-institution retrospective study identified 4435 patients with a recorded body mass index who underwent a lumbar puncture with a 22-ga pencil-tip Whitacre needle, a 20-ga bevel-tip Quincke needle, or a 22-ga Quincke needle. The groups were stratified by body mass index. We compared epidural blood patch rates between 22-ga pencil-tip Whitacre needles versus 22-ga Quincke needles and 22-ga Quincke needles versus 20-ga bevel-tip Quincke needles using the Fischer exact test and χ2 test. RESULTS: Postdural puncture headache necessitating an epidural blood patch was statistically more likely using a 22-ga Quincke needle in all patients (P < .001) and overweight (P = .03) and obese (P < .001) populations compared with using a 22-ga pencil-tip Whitacre needle. In the normal body mass index population, there was no statistically significant difference in epidural blood patch rates when using a 22-ga pencil-tip Whitacre needle compared with a 22-ga Quincke needle (P = .12). There was no significant difference in epidural blood patch rates when comparing a 22-ga Quincke needle versus a 20-ga bevel-tip Quincke needle in healthy (P = .70), overweight (P = .69), or obese populations (P = .44). CONCLUSIONS: Using a 22-ga pencil-tip Whitacre needle resulted in lower epidural blood patch rates compared with a 22-ga Quincke needle in all patients. Subgroup analysis demonstrated a statistically significant difference in epidural blood patch rates in overweight and obese populations, but not in patients with a normal body mass index.

Counterion-Dependent Mechanisms of DNA Origami Nanostructure Stabilization Revealed by Atomistic Molecular Simulation.

The DNA origami technique has proven to have tremendous potential for therapeutic and diagnostic applications like drug delivery, but the relatively low concentrations of cations in physiological fluids cause destabilization and degradation of DNA origami constructs preventing in vivo applications. To reveal the mechanisms behind DNA origami stabilization by cations, we performed atomistic molecular dynamics simulations of a DNA origami rectangle in aqueous solvent with varying concentrations of magnesium and sodium as well as polyamines like oligolysine and spermine. We explored the binding of these ions to DNA origami in detail and found that the mechanism of stabilization differs between ion types considerably. While sodium binds weakly and quickly exchanges with the solvent, magnesium and spermine bind close to the origami with spermine also located in between helices, stabilizing the crossovers characteristic for DNA origami and reducing repulsion of parallel helices. In contrast, oligolysine of length ten prevents helix repulsion by binding to adjacent helices with its flexible side chains, spanning the gap between the helices. Shorter oligolysine molecules with four subunits are weak stabilizers as they lack both the ability to connect helices and to prevent helix repulsion. This work thus shows how the binding modes of ions influence the stabilization of DNA origami nanostructures on a molecular level.

Electron Spin Coherence in Optically Excited States of Rare-Earth Ions for Microwave to Optical Quantum Transducers.

Efficient and reversible optical to microwave transducers are required for entanglement transfer between superconducting qubits and light in quantum networks. Rare-earth-doped crystals with narrow optical and spin transitions are a promising system for enabling these devices. Current resonant transduction approaches use ground-state electron spin transitions that have coherence lifetimes often limited by spin flip-flop processes and spectral diffusion, even at very low temperatures. We investigate spin coherence in an optically excited state of an Er^{3+}: Y_{2}SiO_{5} crystal at temperatures from 1.6 to 3.5 K for a low 8.7 mT magnetic field compatible with superconducting resonators. Spin coherence and population lifetimes of up to 1.6 µs and 1.2 ms, respectively, are measured by optically detected spin echo experiments. Analysis of decoherence processes suggest that ms coherence can be reached at lower temperatures for the excited-state spins, whereas ground-state spin coherence would be limited to a few µs due to resonant interactions with other Er^{3+} spins in the lattice and greater instantaneous spectral diffusion from the radio-frequency control pulses. We propose a quantum transducer scheme with potential for close to unity efficiency that exploits the advantages offered by spin states of the optically excited electronic energy levels.

Mimicking Hierarchical Complexity of the Osteochondral Interface Using Electrospun Silk-Bioactive Glass Composites.

The anatomical complexity and slow regeneration capacity of hyaline cartilage at the osteochondral interface pose a great challenge in the repair of osteochondral defects (OCD). In this study, we utilized the processing feasibility offered by the sol derived 70S bioactive glass and silk fibroin (mulberry Bombyx mori and endemic Indian non-mulberry Antheraea assama), in fabricating a well-integrated, biomimetic scaffolding matrix with a coherent interface. Differences in surface properties such as wettability and amorphousness between the two silk groups resulted in profound variations in cell attachment and extracellular matrix protein deposition. Mechanical assessment showed that the biphasic composites exhibited both an elastic region pertinent for cartilage tissue and a stiff compression resistant region simulating the bone phase. In vitro biological studies revealed that the biphasic mats presented spatial confinement for the growth and maturation of both osteoblasts and chondrocytes, marked by increased alkaline phosphatase (ALP) activity, osteopontin (OPN), sulfated glycosaminoglycan (sGAG) and collagen secretion in the cocultured mats. The non-mulberry silk based biphasic composite mats performed better than their mulberry counterpart, as evidenced by enhanced expression levels of key cartilage and bone specific marker genes. Therefore, the developed biphasic scaffold show great promise for improving the current clinical strategies for osteochondral tissue repair.

Effects of fabrication methods on spin relaxation and crystallite quality in Tm-doped Y3AI5O12 powders studied using spectral hole burning.

High-quality rare-earth-ion (REI) doped materials are a prerequisite for many applications such as quantum memories, ultra-high-resolution optical spectrum analyzers and information processing. Compared to bulk materials, REI doped powders offer low-cost fabrication and a greater range of accessible material systems. Here we show that crystal properties, such as nuclear spin lifetime, are strongly affected by mechanical treatment, and that spectral hole burning can serve as a sensitive method to characterize the quality of REI doped powders. We focus on the specific case of thulium doped Y3AI5O12 (Tm:YAG). Different methods for obtaining the powders are compared and the influence of annealing on the spectroscopic quality of powders is investigated on a few examples. We conclude that annealing can reverse some detrimental effects of powder fabrication and, in certain cases, the properties of the bulk material can be reached. Our results may be applicable to other impurities and other crystals, including color centers in nano-structured diamond.

Electrohydrodynamic encapsulation of cisplatin in poly (lactic-co-glycolic acid) nanoparticles for controlled drug delivery.

Targeted delivery of potent, toxic chemotherapy drugs, such as cisplatin, is a significant area of research in cancer treatment. In this study, cisplatin was successfully encapsulated with high efficiency (>70%) in poly (lactic-co-glycolic acid) polymeric nanoparticles by using electrohydrodynamic atomization (EHDA) where applied voltage and solution flow rate as well as the concentration of cisplatin and polymer were varied to control the size of the particles. Thus, nanoparticles were produced with three different drug:polymer ratios (2.5, 5 and 10wt% cisplatin). It was shown that smaller nanoparticles were produced with 10wt% cisplatin. Furthermore, these demonstrated the best sustained release (smallest burst release). By fitting the experimental data with various kinetic models it was concluded that the release is dependent upon the particle morphology and the drug concentration. Thus, these particles have significant potential for cisplatin delivery with controlled dosage and release period that are crucial chemotherapy parameters.