Neonatal orbital abscess

PURPOSE: To describe two cases of orbital abscess in neonates and to review the literature of orbital cellulitis in neonates. DESIGN: Two interventional case reports. METHODS: Photographs, orbital computed tomography scans, and full pediatric examination were obtained in two cases of orbital abscess in neonates. RESULTS: Acute ethmoiditis with orbital abscess formation was found in both infants. In one of them, Staphylococcus aureus was identified as the source of infection. CONCLUSIONS: The clinical findings of our cases concur with the literature (eight cases) indicating that orbital abscess caused by Staphylococcal ethmoiditis is the most common form of orbital cellulitis in neonates.     

Transcellular bicarbonate transport in rabbit gallbladder epithelium: mechanisms and effects of cyclic AMP

HCO₃ permeation through rabbit gallbladder epithelium has been investigated in vitro using voltage-clamp, pH-stat and microelectrode techniques. Mucosa-to-serosa flux of HCO₃ (4.9 mol cm^–2h^–1) was dependent on luminal Na and inhibited by amiloride (1 mmol/l, luminal bath), methazolamide (0.1 mmol/l, both sides), and ouabain (30 mol/l, serosal bath). Maximal rates of serosa-to-mucosa flux of HCO₃ (2.8 mol cm^–2h^–1) required serosal Na and mucosal Cl. This flux was inhibited by ouabain, 4-acetamido-4-isothiocyanato-stilbene-2,2-disulfonic acid (1 mmol/l, serosal bath), and 5-nitro-2-(3-phenylpropylamino)-benzole acid (0.1 mmol/l, luminal bath). Ineffective were methazolamide (0.1 mmol/l, both sides) and amiloride (1 mmol/l, serosal bath). 8-Br-cAMP (1 mmol/l, serosal bath) largely inhibited the absorptive and moderately stimulated the secretory flux. In tissue conductance, short-circuit current, and transmural voltage prostaglandin E₁ (1 mol/l, serosal bath) and 8-Br-cAMP caused moderate to negligible increases. No significant alterations of apical membrane potential ( –65 mV) and the apparent ratio of membrane resistances (R_a/R_b;1.9) were found. Cell membranes responded to luminal Cl removal mostly with a slow hyperpolarization that was mitigated by 8-Br-cAMP or, in some cases, converted into a small, transient depolarization. Our results are best explained by transcellular HCO₃ transport in both directions. In secretion, basolateral HCO₃ entry occurs by some form of co-transport with Na, and apical exit by Cl/HCO₃ exchange. cAMP opens no major electrodiffusive pathway for apical anion efflux. In absorption, HCO₃ import from the lumen into the cell is secondary to cAMP-sensitive Na/H exchange.     

Hydrophobic interactions in Plasmodium falciparum invasion into human erythrocytes

Human glycophorins block in vitro invasion of Plasmodium falciparum merozoites into human erythrocytes. A segment of glycophorin A which appears to be involved in the inhibition, is at, or adjacent to, the membrane-spanning domain of the molecule. To study the role of hydrophobic interactions in the inhibition, a series of proteins were derivatized with lipophilic side groups, and tested for inhibitory activity. Glycophorin A became five times more inhibitory after derivatization with nitrobenzylfurazan groups. Bovine serum albumin was derivatized to different degrees with nitrobenzylfurazan, dinitrobenzyl, trinitrobenzyl, dansyl, disulfonic stilbene, and fluorescein groups. The presence of hydrophobic side groups on the protein rendered it highly inhibitory to invasion, whereas the presence of hydrophilic substitutes such as disulfonic stilbenes did not. Other soluble proteins such as human serum albumin, transferrin, ovalbumin, fetuin and casein derivatized with dinitrobenzyl groups, were also found to block invasion. Inhibition was not a result of toxic effects of the protein derivatives on parasite metabolism or development. A minimum of ten hydrophobic side groups per bovine serum albumin was required in order to elicit appreciable inhibition. The invasion blocking activity was highly correlated with the rate and affinity of binding of the derivatized macromolecules to heptyl-Sepharose. The latter provided a quantitative measure for the capacity of amphiphiles to undergo hydrophobic interactions with insoluble matrices. The results of the present study indicate that hydrophobic interactions may be an essential component in the invasion of P. falciparum merozoites into human erythrocytes.     

Volume-sensitive chloride currents in primary cultures of human fetal vas deferens epithelial cells

Using the patch-clamp technique, we have identified a large, outwardly rectifying, Cl⁻-selective whole-cell current in primary cultures of human vas deferens epithelial cells. Whole-cell currents were time- and voltage-dependent and displayed inactivation following depolarising pulses ≥ 60 mV. Currents were equally permeable to bromide (P _Br/P _Cl = 1.05 ± 0.04), iodide (P _I/P _Cl = 1.06 ± 0.07) and Cl⁻, but significantly less permeable to gluconate (P _Gluc/P _Cl = 0.23 ± 0.03). Currents spontaneously increased with time after establishing a whole-cell recording, but could be inhibited by exposure to a hypertonic bath solution which reduced inward currents by 68 ± 4%. Subsequent exposure of the cells to a hypotonic bath solution led to a 418 ± 110% increase in inward current, indicating that these currents are regulated by osmolarity. 4,4′-Diisothiocyanatostilbene-2,2′-disulphonic acid (100 μM) produced a rapid and reversible voltage-dependent block (60 ± 5% and 10 ± 7% inhibition of current, measured at ± 60 mV, respectively). Dideoxyforskolin (50 μM) also reduced the volume-sensitive Cl⁻ current, but with a much slower time course, by 41 ± 13% and 32 ± 16% (measured at ± 60 mV, respectively). Tamoxifen (10 μM) had no effect on the whole-cell Cl⁻ current. These results suggest that vas deferens epithelial cells possess a volume-sensitive Cl⁻ conductance which has biophysical and pharmacological properties broadly similar to volume-sensitive Cl⁻ currents previously described in a variety of cell types. Received: 25 January/Accepted: 25 April 1996     

Glycosidic intermediates identified in 1H MR spectra of intact tumour cells may contribute to the clarification of aspects of glycosylation pathways

The glycosylation process, through the addition of carbohydrates, is a major post‐translational modification of proteins and glycolipids. Proteins may be glycosylated in either the secretory pathway leading to N‐linked or O‐linked glycoproteins or as nucleocytoplasmic glycosylation that targets only single proteins involving a single β‐linked N‐acetylglucosamine. In both cases, the key precursors are the uridine diphospho‐N‐acetylhexosamines synthesised by the hexosamine biosynthetic pathway. Furthermore, uridine diphospho‐N‐acetylglucosamine participates in the biosynthesis of sialic acid. In this work, we propose MRS for the detection of uridine diphospho‐N‐acetylhexosamines visible in high‐resolution MR spectra of intact cells from different human tumours. Signals from the nucleotide and amino sugar moieties, including amide signals observed for the first time in whole cells, are assigned, also taking advantage of spectral changes that follow cell treatment with ammonium chloride. Finally, parallel changes in uridine diphospho‐N‐acetylhexosamines and glutamine pools, observed after pH changes induced by ammonium chloride in the different tumour cell lines, may provide more details on the glycosylation processes. Copyright © 2010 John Wiley & Sons, Ltd.     

K–Cl cotransport function and its potential contribution to cardiovascular disease

K–Cl cotransport is the coupled electroneutral movement of K and Cl ions carried out by at least four protein isoforms, KCC1-4. These transporters belong to the SLC12A family of coupled cotransporters and, due to their multiple functions, play an important role in the maintenance of cellular homeostasis. Significant information exists on the overall function of these transporters, but less is known about the role of the specific isoforms. Most functional studies were done on K–Cl cotransport fluxes without knowing the molecular details, and only recently attention has been paid to the isoforms and their individual contribution to the fluxes. This review summarizes briefly and updates the information on the overall functions of this transporter, and offers some ideas on its potential contribution to the pathophysiological basis of cardiovascular disease. By virtue of its properties and the cellular ionic distribution, K–Cl cotransport participates in volume regulation of the nucleated and some enucleated cells studied thus far. One of the hallmarks in cardiovascular disease is the inability of the organism to maintain water and electrolyte balance in effectors and/or target tissues. Oxidative stress is another compounding factor in cardiovascular disease and of great significance in our modern life styles. Several functions of the transporter are modulated by oxidative stress, which in turn may cause the transporter to operate in either “overdrive” with the purpose to counteract homeostatic changes, or not to respond at all, again setting the stage for pathological changes leading to cardiovascular disease. Intracellular Mg, a second messenger, acts as an inhibitor of K–Cl cotransport and plays a crucial role in regulating the activity of protein kinases and phosphatases, which, in turn, regulate a myriad of cellular functions. Although the role of Mg in cardiovascular disease has been dealt with for several decades, this chapter is evolving nowadays at a faster pace and the relationships between Mg, K–Cl cotransport, and cardiovascular disease is an area that awaits further experimentation. We envision that further studies on the role of K–Cl cotransport, and ideally on its specific isoforms, in mammalian cells will add missing links and help to understand the cellular mechanisms involved in the pathophysiology of cardiovascular disease.     

Mechanism of sodium chloride reabsorption in the ascending thin limb of Henle's loop

Summary The ascending thin limb of Henle's loop has been one of the most mysterious nephron segments because of the unique characteristics of its NaCl and water transport systems. The ascending thin limb is essentially impermeable to water under all circumstances. The majority of luminal sodium ions (Na⁺) are reabsorbed across the shallow tight junction between the ascending thin limb cells, as the apical membrane of the ascending thin limb is impermeable to Na⁺. Intracellular Na⁺ activity is maintained at a low level by a ouabain-sensitive Na⁺/K⁺-ATPase. Intracellular pH is maintained by an amiloridesensitive sodium ion-hydrogen ion (Na⁺/H⁺) antiporter, which depends on calmodulin. Intracellular calcium ion (Ca²⁺) activity is maintained at a low level by a calmodulin-sensitive Ca²⁺ pump and a dihydropyridine-sensitive Ca²⁺ channel. In the ascending thin limb, Cl⁻ is reabsorbed across the Cl⁻ channels in both the luminal and basolateral membranes. This channel is sensitive to various anion transport inhibitors. Chloride ion transport in the ascending thin limb is also sensitive to intra- and extracellular pH. Physiologic regulation of the Cl⁻ channel by the vasopressin V2 receptor has been identified. Our studies have elucidated the precise mechanism of NaCl transport in the ascending thin limb, and suggest that this countercurrent exchange system in the ascending thin limb is not effected by any energy-dependent process, but occurs as passive simple diffusion of Na⁺ via tight junctions as a result of facilitated transport of Cl⁻ across the cell membranes. This review was presented at the 39th Annual Meeting of the Japanese Society of Nephrology and received an Oshima Award for Young Investigators     

Gene expression profile changes induced by acute toxicity of [C16mim]Cl in loach (Paramisgurnus dabryanus)

Ionic liquids (ILs) are widely used as reaction media in various commercial applications. Many reports have indicated that most ILs are poorly decomposed by microorganisms and are toxic to aquatic organisms. In this study, differential gene expression profiling was conducted using a suppression subtraction hybridization cDNA library from hepatic tissue of the loach (Paramisgurnus dabryanus) after exposure to 1‐hexadecyl‐3‐methylimidazolium chloride ([C₁₆mim]Cl), a representative IL. Two hundred and fifty‐nine differentially expressed candidate genes, whose expression was altered by >2.0‐fold by the [C₁₆mim]Cl treatment, were identified, including 127 upregulated genes and 132 downregulated genes. A gene ontology analysis of the known genes isolated in this study showed that [C₁₆mim]Cl‐responsive genes were involved in cell cycle, stimulus response, defense response, DNA damage response, oxidative stress responses, and other biological responses. To identify candidate genes that may be involved in [C₁₆mim]Cl‐induced toxicity, 259 clones were examined by Southern blot macroarray hybridization, and 20 genes were further characterized using quantitative real‐time polymerase chain reaction. Finally, six candidate genes were selected, including three DNA damage response genes, two toxic substance metabolic genes, and one stress protein gene. Our results indicate that these changes in gene expression are associated with [C₁₆mim]Cl‐induced toxicity, and that these six candidate genes can be promising biomarkers for detecting [C₁₆mim]Cl‐induced toxicity. Therefore, this study demonstrates the use of a powerful assay to identify genes potentially involved in [C₁₆mim]Cl toxicity, and it provides a foundation for the further study of related genes and the molecular mechanism of [C₁₆mim]Cl toxicity. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 404–416, 2017.     

Hypothyroidism impairs chloride homeostasis and onset of inhibitory neurotransmission in developing auditory brainstem and hippocampal neurons

Thyroid hormone (TH) deficiency during perinatal life causes a multitude of functional and morphological deficits in the brain. In rats and mice, TH dependency of neural maturation is particularly evident during the first 1–2 weeks of postnatal development. During the same period, synaptic transmission via the inhibitory transmitters glycine and GABA changes from excitatory depolarizing effects to inhibitory hyperpolarizing ones in most neurons [deploarizing–hyperpolarizing (D/H) shift]. The D/H shift is caused by the activation of the K⁺–Cl⁻ co-transporter KCC2 which extrudes Cl⁻ from the cytosol, thus generating an inward-directed electrochemical Cl⁻ gradient. Here we analyzed whether the D/H shift and, consequently, the onset of inhibitory neurotransmission are influenced by TH. Gramicidin perforated-patch recordings from auditory brainstem neurons of experimentally hypothyroid rats revealed depolarizing glycine effects until postnatal day (P)11, i.e. almost 1 week longer than in control rats, in which the D/H shift occurred at ∼P5–6. Likewise, until P12–13 the equilibrium potential E_Gly in hypothyroids was more positive than the membrane resting potential. Normal E_Gly could be restored upon TH substitution in P11–12 hypothyroids. These data demonstrate a disturbed Cl⁻ homeostasis following TH deficiency and point to a delayed onset of synaptic inhibition. Interestingly, immunohistochemistry demonstrated an unchanged KCC2 distribution in hypothyroids, implying that TH deficiency did not affect KCC2 gene expression but may have impaired the functional status of KCC2. Hippocampal neurons of hypothyroid P16–17 rats also demonstrated an impaired Cl⁻ homeostasis, indicating that TH may have promoted the D/H shift and maturation of synaptic inhibition throughout the brain.     

BO-0742, a derivative of AHMA and N-mustard,has selective toxicity to drug sensitive and drug resistant leukemia cells and solid tumors

This is a preclinical study of BO-0742, a derivative of 3-(9-acridinylamino)-5-hydroxymethyl-aniline (AHMA) and N-mustard, as an anti-cancer agent. MTS assays revealed a broad spectrum of anti-cancer activities in vitro, with the greatest cytotoxicity against leukemia and neuroblastoma including those with drug resistant characteristics, and a good therapeutic index with leukemia being 10–40 times more sensitive to BO-0742 than hematopoietic progenitors. Administration of BO-0742 at an optimal dose schedule based on its pharmacokinetics significantly suppressed the growth of xenografts of human breast and ovarian cancers in mice. Thus, BO-0742 is a potent anti-cancer agent worthy of further clinical development.