Cerumen impaction

Cerumen impaction represents the most common otologic problem encountered by physicians. It can affect up to 6% of the general population and a much higher percentage in the mentally retarded population. Cerumen is a mixture of secretory products of two glands in the external auditory canal where it serves a protective function. The external auditory canal possesses a unique anatomy and physiology that permits an efficient self-cleaning system. In most cases, a breakdown in the epithelial migration of the external auditory canal is thought to cause cerumen impaction. The management of cerumen impaction include direct removal, irrigation, and the use of cerumenolytics.     

Investigation of the effects of mechanical post‐processing with a colloid mill on the texture properties of stirred yogurt

Texture properties of stirred low‐fat yogurt were investigated in terms of processing after fermentation. The yogurt gel was pumped through a colloid mill at two gap widths and various peripheral velocities of the rotor. The storage modulus and yield stress were measured after 1 day and after 3 weeks, and the occurrence of syneresis was noted. The main factor for the structural degradation in the shear gap was the mean peripheral velocity of the rotor, rather than the apparent shear rate. Syneresis is related to a certain level of the storage modulus. The yield stress correlated with the storage modulus.     

Towards All-Solid-State Polymer Batteries: Going Beyond PEO with Hybrid Concepts

To go beyond polyethylene oxide in lithium metal batteries, a hybrid polymer/oligomer cell design is presented, where an ester oligomer provides high ionic conductivity of 0.2 mS cm⁻¹ at 40 °C within thicker composite cathodes with active mass loadings of up to 11 mg cm⁻² (LiNbO₃-coated) LiNi_0.6Mn_0.2Co_0.2 (NMC622), while a 30 µm thin scaffold-supported polymer electrolyte affords mechanical stability. Corresponding discharge capacities of the hybrid cells exceed 170 mAh g⁻¹ (11 mg cm⁻²) or 160 mAh g⁻¹ (6 mg cm⁻²) at rates of either 0.1 or 0.25 C. Multilayer pouch cells are projected to enable energy densities of 235 Wh L⁻¹ (6 mg cm⁻²) and even up to 356 Wh L⁻¹ (11 mg cm⁻²), clearly superior to other reported polymer-based cell designs. Polyester electrolytes are environmentally benign and safer compared to common liquid electrolytes, while the straightforward synthesis and affordability of precursors render hybrid polyester electrolytes suitable candidates for future application in solid-state lithium metal batteries.     

Clarification of the relationship between free radical spin trapping and carbon tetrachloride metabolism in microsomal systems

It has been proposed that the C-phenyl-N-tert-butylnitrone/trichloromethyl radical adduct (PBN/.CCl3) is metabolized to either the C-phenyl-N-tert-butylnitrone/carbon dioxide anion radical adduct (PBN/.CO2-) or the glutathione (GSH) and CCl4-dependent PBN radical adduct (PBN/[GSH-.CCl3]). Inclusion of PBN/.CCl3 in microsomal incubations containing GSH, nicotinamide adenine dinucleotide phosphate (NADPH), or GSH plus NADPH produced no electron spin resonance (ESR) spectral data indicative of the formation of either the PBN/[GSH-.CCl3] or PBN/.CO2- radical adducts. Microsomes alone or with GSH had no effect on the PBN/.CCl3 radical adduct. Addition of NADPH to a microsomal system containing PBN/.CCl3 presumably reduced the radical adduct to its ESR-silent hydroxylamine because no ESR signal was observed. The Folch extract of this system produced an ESR spectrum that was a composite of two radicals, one of which had hyperfine coupling constants identical to those of PBN/.CCl3. We conclude that PBN/.CCl3 is not metabolized into either PBN/[GSH-.CCl3] or PBN/.CO2- in microsomal systems.     

Phosphorylation of tobacco eukaryotic translation initiation factor 4A upon pollen tube germination

Eukaryotic translation initiation factor eIF-4A is a member of the DEAD box family of RNA helicases and RNA-dependent ATPases. In tobacco, eIF-4A is encoded by a gene family with one isoform, eIF-4A8, being exclusively expressed in pollen. This pollen-specific isoform is a candidate for mediating translational control in the developing gametophyte. Here we show that eIF-4A is barely phosphorylated in mature pollen, but during pollen tube germination, two isoforms of eIF-4A become phosphorylated. Phosphoamino acid analysis indicated phosphorylation of threonine. In order to determine whether pollen-specific eIF-4A8 is among the phosphorylated isoforms, we raised transgenic tobacco plants overexpressing eIF-4A8 containing a histidine tag. Hereby, we could show that indeed eIF-4A8 is modified through phosphorylation. The biological relevance of the phosphorylation of eIF-4A is discussed.     

Inability to detect Chlamyodomonas microtubule assembly in vitro: possible implications to the in vivo regulation of microtubule assembly

It has been demonstrated that the in vitro assembly of microtubules from Chlamydomonas preparations does not occur under a wide range of conditions, including those efficacious for mammalian brain tubulin. This incompetence of Chlamydomonas extracts to form microtubules is independent of the tubulin concentration, the presence of added nucleotides or an added seed, temperature, or the concentration of divalent cation. However, an amorphous aggregate was observed under certain conditions, who composition was mainly tubulin. The in vitro reassembly of microtubules in gerbil brain extracts is inhibited by Chlamydomonas preparations. Fractionation of the Chlamydomonas extracts by column chromatography suggests that the inhibitory component is Chlamydomonas tubulin itself. The mechanism of this inhibition is unknown, but reassembly experiments indicate that the 2 types of tubulins cannot copolymerize. We suggest that the Chlamydomonas tubulin, derived from a cytoplasmic pool, requires to be activated prior to its in vivo polymerization into microtubules.     

Adenovirus-mediated gene transfer of inhibitors of apoptosis protein delays apoptosis in cerebellar granule neurons

The inhibitor of apoptosis (IAP) family of antiapoptotic genes, originally discovered in baculovirus, exists in animals ranging from insects to humans. Here, we investigated the ability of IAPs to suppress cell death in both a neuronal model of apoptosis and excitotoxicity. Cerebellar granule neurons undergo apoptosis when switched from 25 to 5 mM potassium, and excitotoxic cell death in response to glutamate. We examined the endogenous expression of four members of the IAP family, X chromosome-linked IAP (XIAP), rat IAP1 (RIAP1), RIAP2, and neuronal apoptosis inhibitory protein (NAIP), by semiquantitative reverse PCR and immunoblot analysis in cultured cerebellar granule neurons. Cerebellar granule neurons express significant levels of RIAP2 mRNA and protein, but expression of RIAP1, NAIP, and XIAP was not detected. RIAP2 mRNA content and protein levels did not change when cells were switched from 25 to 5 mM potassium. To determine whether ectopic expression of IAP influenced neuronal survival after potassium withdrawal or glutamate exposure, we used recombinant adenoviral vectors to target XIAP, human IAP1 (HIAP1), HIAP2, and NAIP into cerebellar granule neurons. We demonstrate that forced expression of IAPs efficiently blocked potassium withdrawal-induced N-acetyl-Asp-Glu-Val-Asp-specific caspase activity and reduced DNA fragmentation. However, neurons were only protected from apoptosis up to 24 h after potassium withdrawal, but not at later time points, suggesting that IAPs delay but do not block apoptosis in cerebellar granule neurons. In contrast, treatment with 100 microM or 1 mM glutamate did not induce caspase activity and adenoviral-mediated expression of IAPs had no influence on subsequent excitotoxic cell death.     

Endotoxin impairs the engraftment of rat islets transplanted beneath the kidney capsule of C57BL/6-mice

The primary objective of this investigation was to determine the effect of endotoxin on islet xenograft survival within the first three days after transplantation. Pancreatic islets from Lewis rats were prepared under endotoxin-free conditions with Liberase (Boehringer) and purified by centrifugation on endotoxin-free Ficoll/Histopaque. After overnight incubation, with or without 10 microg/ml endotoxin, the islets were transplanted beneath the kidney capsule of normoglycemic C57Bl/6-mice. Three days later, kidneys were removed and their insulin content were measured. We could demonstrate significant differences (P<0.01) in insulin recovery between lipopolysaccharide-free and lipopolysaccharide-containing grafts. In case of endotoxin contaminated islets, we found only 13+/-2% (n=9) of the original insulin content, in contrast to 53+/-7% (n=9) when endotoxin-free islets where grafted. In experiments with islets isolated by use of conventional (lipopolysaccharide-containing) collagenase, and then cultured in endotoxin-free medium, insulin recovery three days after transplantation was 36+/-1% (n=13).     

Differences in prostate size between patients from University and Veterans Affairs Medical Center populations

We have previously determined that Nippostrongylus brasiliensis secretes three monomeric nonamphiphilic (G1na) variants of acetylcholinesterase (AChE) with broadly similar properties. In this study we have examined AChE expression in somatic extracts of N. brasiliensis and report the identification of an additional enzyme which is not secreted. The enzyme was resolved by sucrose density gradient centrifugation with a sedimentation coefficient of 10.2 S which was shifted to 9.4 S in the presence of Triton X-100, identifying the enzyme as a tetrameric amphiphilic (G4a) form. The amphiphilic properties of this enzyme were confirmed by charge-shift electrophoresis, in which migration was accelerated by interaction with sodium deoxycholate. The enzyme showed low activity with butyrylthiocholine, and a Michaelis constant of 91 +/- 13 microM for acetylthiocholine was determined. It was highly sensitive to the AChE-specific inhibitor bis (4-allyldimethylammoniumphenyl)pentan-3-one dibromide, with an IC50 of 6.5 +/- 0.4 microM, but was also inhibited by the butyrylcholinesterase-specific inhibitor tetramonoisopropylpyrophosphortetramide, albeit with a higher IC50 of 46.5 +/- 6.1 microM. This enzyme can therefore be distinguished from the secreted AChEs by its amphiphilic properties, sedimentation in sucrose gradients, and sensitivity to cholinesterase inhibitors.