Preparation of nanoparticles composed with bioinspired 2-methacryloyloxyethyl phosphorylcholine polymer

The poly(L-lactic acid) nanoparticles immobilized with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, which has excellent blood compatibility, were prepared by a solvent evaporation technique using the water-soluble amphiphilic MPC polymer as an emulsifier and a surface modifier. The diameter and zeta-potential of the obtained nanoparticles strongly depended on the concentration of the MPC polymer. When the nanoparticles were prepared in 1.0 mg/ml of an MPC polymer aqueous solution, the diameter was 221 nm which was determined by atomic force microscopy and dynamic light scattering measurements. The X-ray photoelectron spectroscopic analysis indicated that the phosphorylcholine groups of the MPC unit were located at the surface of the nanoparticles, that is, the MPC polymer was immobilized on the PLA particles and the surface zeta-potential was -2.5 mV. Various hydrophobic fluorescence probes could permeate through the MPC polymer layer and adsorb on the PLA surface. The amount of bovine serum albumin adsorbed on the nanoparticles was significantly smaller compared with that on the conventional polystyrene nanoparticles. It is suggested that the nanoparticles immobilized with the MPC polymer have the potential for use as both a novel drug carrier and diagnostic reagent which can come in contact with blood components.     

Prevalence and persistence of depression in patients with implantable cardioverter defibrillator: a 2-year longitudinal study

Background: It is unclear whether depression persists in patients with implantable cardioverter defibrillators (ICDs). We evaluated the prevalence and persistence of depression in ICD patients over a 2‐year period. Methods: The study included 90 consecutively hospitalized patients. Patients underlying heart disease was 24% coronary artery disease, 29% idiopathic dilated cardiomyopathy, 24% hypertrophic cardiomyopathy, 13% idiopathic VF/long QT syndrome and miscellaneous conditions 11%. A secondary indication for ICD implantation was present in 20 patients. All patients completed the Zung Self‐Rating Depression Scale (SDS) at study baseline and at the their routine follow‐up visit 2 years after the baseline questionnaire. Delivery of ICD therapies was tracked throughout the 2 years. Results: Depression, indicated by a Zung SDS index score exceeding 60, was present in 29 (32%) of patients at study baseline. Depression was present in 11/51 (21%) patients scheduled to undergo ICD implantation, 2/2 (100%) patients whose device was upgraded to a CRT‐D, 3/14 (21%) patients who had undergone pulse generator replacement, 7/14 (50%) patients who experienced electrical storm and 6/9 (66%) patients hospitalized with acute decompensated heart failure. NYHA functional class III was significantly associated with depression at baseline (HR 6.7, 95% CI 1.68–27.2, p = 0.0007). No differences were noted for female gender, demographics, β‐blocker use, or LVEF ≤35% (p = ns). Depression was present in 25 (28%) of patients at 2 years follow‐up, persisting in 21 (72%) of patients whose Zung SDS scores were elevated at baseline. The median time from ICD shock therapy to completion of the 2 year questionnaire was 9 months (range, 1–22). Patients who were depressed (9/25, 36%) experienced more shocks than non‐depressed patients (6/65, 9%) after 2 years (p = 0.002). Conclusions: Depression is not uncommon among patients who meet criteria for ICD implantation and persists over time particularly when functional status is impaired. Depression is associated with a higher incidence shock therapy. (PACE 2010; 33:1455–1461)     

Three-dimensional studies of the cytoskeleton of cultured hepatocytes: A quick-freezing and deep-etching study

Summary The ultrastructure of the cytoskeleton of cultured mouse hepatocytes was studied by a quick-freezing and deep-etching method. Isolated mouse hepatocytes were cultured on collagen gels for 48 h, fixed in paraformaldehyde and centrifuged to prepare cell pellets. The hepatocytes were split open to remove cytoplasmic soluble proteins for replica preparations. Some specimens were decorated with anti-actin antibody or S₁ myosin fragments to identify actin filaments. They were quickly frozen in isopentane-propane mixture, fractured in liquid nitrogen, deeply etched in a freeze-fracture machine and rotary shadowed by platinum and carbon. The basal cell membranes of hepatocytes were in contact with the collagen gels and the apical surface faced the culture medium. Networks of actin filaments were attached to the apical cell membranes, but intermediate filaments were localized along the basal layer. Some intermediate filaments were associated with cell organelles, such as the endoplasmic reticulum. The Golgi apparatus was less associated with the cytoskeleton and showed synthesized materials in the cisternae. Cytoskeletal organization in cultured hepatocytes was revealed three-dimensionally, indicating that the interaction of cell membranes with collagen gels is important for the organization of the cytoskeleton.     

Laterality of vestibular evoked myogenic potentials

To clarify the laterality of acoustically evoked vestibulocollic reflexes with a short latency (vestibular evoked myogenic potentials, VEMPs), responses on the bilateral sternocleidomastoid muscles (SCMs) to unilateral acoustic stimulation were studied. Twenty-one healthy volunteers were enrolled. Surface electrodes were placed on the upper half of each SCM (active) and on the lateral end of the upper sternum (reference). Clicks and 500-Hz tone-bursts (95 dB nHL) were used. All subjects showed positive-negative biphasic responses on the ipsilateral SCM by clicks and tone-bursts. Click-stimulation of 41 of the 42 ears did not evoke any response on the contralateral SCM. However, in one ear, positive-negative biphasic responses were evoked on the contralateral SCM. Recordings on the contralateral SCM by tonebursts showed no response in 32 ears, small positive-nega-tive biphasic responses in four ears, and small negative-positive biphasic responses in six ears. These findings show that VEMPs are ipsilateral-dominant, basically consistent with the hypothesis that they are of saccular origin.     

Prostaglandin D2 increases Cl secretion across canine tracheal epithelium through cyclo-oxygenase stimulation and cAMP production.

Prostaglandin (PG) D2 is one cyclo-oxygenase product of arachidonic acid metabolites that may play a role in the pathogenesis of asthma. To determine the effect of PGD2 on ion transport by airway epithelium and its mechanism of action, we measured bioelectric properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. PGD2 (10(-7) M) increased short-circuit current (Isc) from 5.5 +/- 1.2 to 14.1 +/- 2.9 microA cm-2 (means +/- SE, P less than 0.01) when added to the mucosal solution, and to 22.2 +/- 3.8 microA cm-2 (P less than 0.001) when added to the submucosal solution, an effect that was accompanied by the corresponding increases in transepithelial potential difference and conductance. These effects were dose-dependent. The PGD2-induced increase in Isc was not altered by preincubation of cells with autonomic antagonists (phentolamine, propranolol, atropine), the lipoxygenase inhibitor AA-861, the protein kinase C inhibitor H-7, or the Na channel blocker amiloride, but it was inhibited by each of indomethacin, piroxicam, the Cl channel blocker diphenylamine-2-carboxylate, the Cl transport inhibitor furosemide, and Cl-free medium. Intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels were dose-dependently increased by PGD2. These results suggest that PGD2 may selectively stimulate airway epithelial Cl secretion via cyclo-oxygenase- and cAMP-dependent pathway.     

Evidence for endocytosis-independent infection by human rotavirus

Summary The effects of five lysosomotropic drugs (NH₄Cl, chloroquine, methylamine, amantadine and dansylcadaverine) and cytochalasin B on human rotavirus (HRV KUN strain) and vesicular stomatitis virus (VSV Indiana strain) infection in monkey MA 104 cells were examined. These drugs had little effect on HRV yield but greatly reduced VSV yield. The results strongly suggest that HRV does not require endocytotic activity and intracellular acidic vesicles for the initial stage of infection and support our postulate that HRV enters the target cell by direct penetration of its nucleoid through the cell membrane.     

Serologic characteristics of a human rotavirus isolate, AU-1, which has a "long" RNA pattern and subgroup I specificity

An unusual human rotavirus (HRV) isolate, designated AU-1, has a "long" RNA electrophoretic pattern and subgroup I specificity, in contrast to properties common to HRVs previously isolated. Hemagglutination activity of the AU-1 strain was demonstrated using erythrocytes of 1-day-old chicken. Neutralization assays revealed that the AU-1 strain was crossneutralized by hyperimmune antisera against the MO strain (serotype 3). However, antiserum directed against a reassortant in which the gene for Vp7 was replaced by the corresponding AU-1 gene neutralized the AU-1 strain to a significantly higher titer than the MO strain.     

Expression of HGF and IGF-1 during regeneration of masseter muscle in <Emphasis Type="Italic">mdx</Emphasis> mice

This study investigated the expression of the growth factors HGF and IGF-1 during the process of muscle regeneration in mdx mice. HGF and IGF-1 are reportedly expressed during the regeneration of muscle tissue in vitro. However, few studies have focused on the role of HGF and IGF-1 during muscle regeneration in mdx mice, which lack expression of the dystrophin gene. In the present study, we examined the expression of HGF and IGF-1 in masseter muscle during muscle regeneration in mdx and B10 (control) mice using histological analysis, immunohistochemistry and Western blotting, as well as examining gene expression by RT-PCR, at 3, 4 and 9 weeks. Mdx mice showed localized HGF and IGF-1 positivity in the cytoplasm of regenerating muscle cells at 3 and 4 weeks, but hardly any reactivity was evident at 9 weeks. The control group was completely negative for IGF-1 at any of the examined time points. Western blotting showed stronger expression of HGF and IGF-1 in mdx mice than in B10 mice at 3 and 4 weeks, but at 9 weeks the expression was absent in both groups. Similar results were obtained using RT-PCR. These present results suggest that HGF and IGF-1 appear to play an important role during regeneration of the masseter muscle in mdx mice.     

Treatment with linezolid in a neonate with meningitis caused by methicillin-resistant Staphylococcus epidermidis

Recent findings have focused on the possible role of linezolid (LZD) as a suitable candidate for the treatment of central nervous system infections. LZD treatment for meningitis has been sporadically reported in adults, but there are no reports in neonates or infants. We report a case of meningitis caused by methicillin-resistant Staphylococcus epidermidis (MRSE) in a neonatal girl. The patient had intraventricular hemorrhage on postnatal day 1 and was treated with ventricular drainage. Twenty-two days after drainage, the patient developed a fever and seizure. Although ampicillin and ceftriaxone were given empirically for meningitis, an increased cell count and protein were observed in cerebrospinal fluid (CSF). Vancomycin (VCM) was administered intravenously because MRSE was detected from CSF 2 days after the administration of ampicillin and ceftriaxone. However, intravenous administration of VCM did not show any effect. Subsequent treatment of LZD successfully reduced the cell count and protein in CSF. Conclusion: LZD may be a treatment option for neonates and infants for drain-associated meningitis caused by MRSE.