Characterization and antibacterial properties of N-halamine-derivatized cross-linked polymethacrylamide nanoparticles

N-halamine-derivatized cross-linked polymethacrylamide nanoparticles with sizes ranging between 18 ± 2.0 and 460 ± 60 nm were prepared via surfactant-free dispersion co-polymerization of methacrylamide (MAA) and the cross-linking monomer N,N-methylenebisacrylamide (MBAA) in an aqueous continuous phase, followed by a chlorination process using sodium hypochlorite. The effect of various polymerization parameters (monomer concentration, initiator type and concentration, polymerization duration, polymerization temperature, and the weight ratio [MBAA]/[MAA]) on the size and size distribution of the produced cross-linked P(MAA–MBAA) nanoparticles was elucidated. The effect of various chlorination parameters (hypochlorite concentration, chlorination period and temperature) on the bound oxidative chlorine atom (Cl) content of the P(MAA–MBAA) nanoparticles was also investigated. The bactericidal activity of these chloramine-derivatized nanoparticles was tested against two common bacterial pathogens (Escherichia coli and Staphylococcus aureus), and they were found to be highly potent. Furthermore, these nanoparticles also exerted their antimicrobial activity against multi-drug resistant (MDR) bacteria, further demonstrating their efficacy.     

Hirschsprung disease associated with total colonic agenesis and imperforate anus—case report and review of the literature

We report a case of Hirschsprung disease associated with total colonic agenesis and high-type imperforate anus in a newborn girl. The patient also presented with uterus bicornis and a single kidney. The treatment procedure is presented together with a review of literature. The presented combination of pathologies has never been described before.     

Preparatory activity in motor cortex reflects learning of local visuomotor skills

In humans, learning to produce correct visually guided movements to adapt to new sensorimotor conditions requires the formation of an internal model that represents the new transformation between visual input and the required motor command. When the new environment requires adaptation to directional errors, learning generalizes poorly to untrained locations and directions, indicating that such learning is local. Here we replicated these behavioral findings in rhesus monkeys using a visuomotor rotation task and simultaneously recorded neuronal activity. Specific changes in activity were observed only in a subpopulation of cells in the motor cortex with directional properties corresponding to the locally learned rotation. These changes adhered to the dynamics of behavior during learning and persisted between learning and relearning of the same rotation. These findings suggest a neural mechanism for the locality of newly acquired sensorimotor tasks and provide electrophysiological evidence for their retention in working memory.     

Multiplexed imaging of surface enhanced Raman scattering nanotags in living mice using noninvasive Raman spectroscopy

Raman spectroscopy is a newly developed, noninvasive preclinical imaging technique that offers picomolar sensitivity and multiplexing capabilities to the field of molecular imaging. In this study, we demonstrate the ability of Raman spectroscopy to separate the spectral fingerprints of up to 10 different types of surface enhanced Raman scattering (SERS) nanoparticles in a living mouse after s.c. injection. Based on these spectral results, we simultaneously injected the five most intense and spectrally unique SERS nanoparticles i.v. to image their natural accumulation in the liver. All five types of SERS nanoparticles were successfully identified and spectrally separated using our optimized noninvasive Raman imaging system. In addition, we were able to linearly correlate Raman signal with SERS concentration after injecting four spectrally unique SERS nanoparticles either s.c. (R² = 0.998) or i.v. (R² = 0.992). These results show great potential for multiplexed imaging in living subjects in cases in which several targeted SERS probes could offer better detection of multiple biomarkers associated with a specific disease.     

Persistent hyperfibrinogenemia in acute ischemic stroke / transient ischemic attack (TIA)

Increased fibrinogen concentration is a well known phenomenon following acute ischemic stroke. However, the natural course of this hyperfibrinogenemia is uncertain. We aimed to clarify whether it is of a transient or more persistent nature in patients who harbor an underlying morbid biology of atherothrombo-inflammation. Venous blood for fibrinogen measurements was obtained from the control group participants and from stroke patients within 24 hours of admission, as well as 12 months following the acute event. In order to perform a time course analysis, we divided our cohort into tiles of time from symptoms' onset and compared the fibrinogen concentrations using ANOVA. Elevated fibrinogen concentrations were found in stroke patients on admission compared with matched controls (p < 0.001). Analysis of variance in the different tertiles of time from symptoms' onset identified that fibrinogen concentrations were already relatively high during the initial phase of the event and did not differ significantly between the tiles (p = 0.268). Moreover, when we calculated the absolute differences between the patients' fibrinogen concentrations and that of the matched controls there was clearly a minor increment during the time course from symptoms' onset in the stroke patients group. In conclusion, persistent hyperfibrinogenemia is present in patients with acute ischemic cerebral events and it might be present during the earlier stages of the disease as presently shown. Prompt and long-term, rather than short term, interventions to reduce the concentrations of this protein might therefore be of relevance.     

Diabetes and the brain: issues and unmet needs

Diabetes mellitus (DM) is associated with an increased risk of mild cognitive impairment, dementia and stroke. The association between DM and dementia appears to be stronger for vascular cognitive impairment than for Alzheimer’s disease, suggesting cerebrovascular disease may be an important factor in cognitive impairment in DM. Although the exact mechanisms by which DM affects the brain remain unclear, changes to brain vasculature, disturbances of cerebral insulin signaling, insulin resistance, glucose toxicity, oxidative stress, accumulation of advanced glycation end products, hypoglycemic episodes, and alterations in amyloid metabolism may all be involved. Cognitive impairment and dementia associated with DM may also be mediated via vascular risk factors, in particular brain ischemia, the occurrence of which can have an additive or synergistic effect with concomitant neurodegenerative processes. To date, no drug has been approved for the treatment of vascular dementia and there are no specific pharmacological treatments for preventing or reducing cognitive decline in patients with DM. Most focus has been on tighter management of vascular risk factors, although evidence of reduced cognitive decline through reducing blood pressure, lipid-lowering or tighter glycemic control is inconclusive. Tailored, multimodal therapies may be required to reduce the risk of cognitive dysfunction and decline in patients with DM. The use of pleiotropic drugs with multimodal mechanisms of action (e.g., cerebrolysin, Actovegin) may have a role in the treatment of cognitive dysfunction and their use may warrant further investigation in diabetic populations.     

Magnetic resonance imaging (MRI) assessment of vocal fold medialization surgery

Historically, clinicians have used subjective assessment and perceptual judgments, supplemented with acoustic measures, aerodynamic studies, and videostroboscopy, to determine the effects of phonosurgery. When phonosurgical results are poor, magnetic resonance imaging (MRI) can be useful in determining how the surgical modifications contributed to the anatomical and functional status of the vocal folds. The authors present examples of MRI following vocal fold medialization by injection, thyroplasty, and arytenoid adduction. Findings reveal that the superior contrast resolution of MRI can precisely identify placement and persistence of injected implants and is particularly helpful in showing effects of the size and shape of alloplastic prostheses on vocal fold displacement. Such information is useful in troubleshooting suboptimal results and in planning revision thyroplasty by defining modification in the design of prostheses and the placement of cartilaginous windows in medialization thyroplasty. MRI can also aid in confirming indications for and limitations of certain procedures.     

Impact of muscarinic agonists for successful therapy of Alzheimer's disease

The M1 muscarinic agonists AF102B, AF150(S) & AF267B--i) restored cognitive impairments in several animal models for AD with an excellent safety margin; ii) elevated alpha-APPs levels; iii) attenuated vicious cycles induced by A beta, and inhibited A beta- and oxidative stress-induced apoptosis; and iv) decreased tau hyperphosphorylation. AF150(S) and AF267B were more effectve than rivastigmine and nicotine in restoring memory impairments in mice with small hippocampi. In apolipoprotein E-knockout mice, AF150(S) restored cognitive impairments and cholinergic hypofunction and decreased tau hyperphosphorylation. In aged microcebes, AF150(S) restored cognitive and behavioral impairments and decreased tau hyperphosphorylation, paired helical filaments and astrogliosis. In rabbits, AF267B & AF150(S) decreased CSF A beta(1-42 & 1-40), while AF102B reduced A beta(1-40). Finally AF102B decreased CSF A beta(total) in AD patients. Taken together, M1 agonists may represent a unique therapy in AD due to their beneficial effects on three major hallmarks of AD--cholinergic hypofunction, A beta and tau protein hyperphosphorylation.     

Chronic fluvoxamine treatment reduces platelet MAO activity in medicated chronic schizophrenics

The effect of add-on fluvoxamine on platelet MAO activity was studied in nine chronic schizophrenic patients on steady antipsychotic treatment. Platelet MAO activity decreased significantly after 5 weeks of treatment and remained depressed. Since fluvoxamine does not inhibit MAO activity in vitro, the findings, which are preliminary, raise the possibility that chronic SSRI treatment may modify MAO production.