Moderate body hypothermia alleviates behavioral and EEG manifestations of audiogenic seizures in metaphit-treated rats

We investigated the effects of hypothermia on the incidence and EEG signs of audiogenic seizures in rats treated with metaphit (1-[1(3isothiocyanatophenyl)-cyclohexyl] piperidine), an experimental model of generalized reflex epilepsy. After i.p. injection with metaphit (10 mg/kg) Wistar rats were exposed to audiogenic stimulation at hourly intervals during the time course of the experiment. After intermittent use of an ice pack 8 h after the metaphit treatment, when seizure was fully developed, the body temperature was reduced to 30 +/- 0.5 degrees C in one half of the rats, and maintained at 37 +/- 0.5 degrees C in the other half. Saline-injected rats served as a control group. In the hypothermia group, the incidence of audiogenic seizures induced by metaphit was completely suppressed during the 3 consecutive testing times, while no signs of epileptiform activity were noted in EEG tracings. The termination of hypothermic treatment resulted in the recovery of seizure susceptibility, and during audiogenic stimulation, bursts of spiking activity were recorded in the EEGs of metaphit-treated rats. These findings indicate that moderate body hypothermia is an effective anticonvulsant treatment for audiogenic seizures in metaphit-treated rats.     

Retinoic acid-induced CD38 expression in HL-60 myeloblastic leukemia cells regulates cell differentiation or viability depending on expression levels

Retinoic acid-induced expression of the CD38 ectoenzyme receptor in HL-60 human myeloblastic leukemia cells is regulated by RARalpha and RXR, and enhanced or prevented cell differentiation depending on the level of expression per cell. RARalpha activation caused CD38 expression, as did RXR activation but not as effectively. Inhibition of MAPK signaling through MEK inhibition diminished the induced expression by both RARs and RXRs. Expression of CD38 enhanced retinoic acid-induced myeloid differentiation and G0 cell cycle arrest, but at higher expression levels, induced differentiation was blocked and retinoic acid induced a loss of cell viability instead. In the case of 1,25-dihydroxyvitamin D3, induced monocytic differentiation was also enhanced by CD38 and not enhanced by higher expression levels, but without induced loss of viability. Expression levels of CD38 thus regulated the cellular response to retinoic acid, either propelling cell differentiation or loss of viability. The cellular effects of CD38 thus depend on its expression level.     

Effect of Cinnamon Oil on icaA Expression and Biofilm Formation by Staphylococcus epidermidis

Staphylococcus epidermidis is notorious for its biofilm formation on medical devices, and novel approaches to prevent and kill S. epidermidis biofilms are desired. In this study, the effect of cinnamon oil on planktonic and biofilm cultures of clinical S. epidermidis isolates was evaluated. Initially, susceptibility to cinnamon oil in planktonic cultures was compared to the commonly used antimicrobial agents chlorhexidine, triclosan, and gentamicin. The MIC of cinnamon oil, defined as the lowest concentration able to inhibit visible microbial growth, and the minimal bactericidal concentration, the lowest concentration required to kill 99.9% of the bacteria, were determined using the broth microdilution method and plating on agar. A checkerboard assay was used to evaluate the possible synergy between cinnamon oil and the other antimicrobial agents. The effect of cinnamon oil on biofilm growth was studied in 96-well plates and with confocal laser-scanning microscopy (CLSM). Biofilm susceptibility was determined using a metabolic 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Real-time PCR analysis was performed to determine the effect of sub-MIC concentrations of cinnamon oil on expression of the biofilm-related gene, icaA. Cinnamon oil showed antimicrobial activity against both planktonic and biofilm cultures of clinical S. epidermidis strains. There was only a small difference between planktonic and biofilm MICs, ranging from 0.5 to 1% and 1 to 2%, respectively. CLSM images indicated that cinnamon oil is able to detach and kill existing biofilms. Thus, cinnamon oil is an effective antimicrobial agent to combat S. epidermidis biofilms.Staphylococcus epidermidis is a gram-positive bacterium and an important agent of nosocomial infections worldwide. Treatment of these infections is increasingly problematic because of the resistance of clinical isolates to an increasing number of antimicrobial agents and, more importantly, due to its ability to grow as a biofilm. Biofilm formation by S. epidermidis (35) can be governed in part by the production of polysaccharide intercellular adhesin. Polysaccharide intercellular adhesin is produced by enzymes encoded by the ica operon which comprises four intercellular adhesion genes: icaA, icaB, icaC, and icaD. The expression of the ica operon and biofilm formation are tightly regulated by icaR under in vitro conditions (15). Biofilm formation can be influenced by changing environmental conditions, such as the presence of subinhibitory concentrations of antimicrobials like tetracycline and quinopristin-dalfopristin, as well as high temperatures, anaerobiosis, ethanol stress, and osmolarity (8, 9, 26, 37).Previous studies have demonstrated that microorganisms within biofilms are less susceptible to antimicrobial treatment than their planktonic counterparts (4), probably due to a combination of poor antimicrobial penetration, nutrient limitation, adaptive stress responses, induction of phenotypic variability, and persister cell formation (28). For this reason, current research has been focused on identifying new compounds that have antimicrobial activity against microorganisms, both in planktonic and biofilm modes of growth. Plant essential oils have been used in food preservation, pharmaceutical therapies, alternative medicine, and natural therapies for many thousands of years (23, 36).Cinnamon oil is one of the essential oils commonly used in the food industry because of its special aroma (6). Cinnamomum is a genus in the family Lauraceae, many species of which are used for spices. One of the species is Cinnamomum burmannii from Indonesia, also called Indonesian cassia (the commercial name is “cinnamon stick”). Several publications have demonstrated the antibacterial activity of cinnamon oil isolated from the bark of this species (12, 18, 22, 39). Cinnamon oil was also shown to be effective against biofilm cultures of Streptococcus mutans and Lactobacillus plantarum (14). In addition, essential oil derived from the leaves of another closely related species within this plant family, Cinnamomum osmophloeum (endemic to Taiwan), had an excellent inhibitory effect on planktonic cultures of nine gram-positive and gram-negative bacteria, including methicillin-resistant Staphylococcus aureus and S. epidermidis (6). Previous studies reported that the predominant active compound found in cinnamon oil was cinnamaldehyde (36, 39). Cinnamaldehyde causes inhibition of the proton motive force, respiratory chain, electron transfer, and substrate oxidation, resulting in uncoupling of oxidative phosphorylation, inhibition of active transport, loss of pool metabolites, and disruption of synthesis of DNA, RNA, proteins, lipids, and polysaccharides (11, 13, 33). In addition, an important characteristic of volatile oils and their components is their hydrophobicity, which enables them to partition into and disturb the lipid bilayer of the cell membrane, rendering them more permeable to protons. Extensive leakage from bacterial cells or the exit of critical molecules and ions ultimately leads to bacterial cell death (36).The susceptibility of S. epidermidis to cinnamon oil derived from the bark of Cinnamomum burmannii, however, has never been published, neither for planktonic organisms nor for staphylococci in a biofilm mode of growth. Hence, the current study was undertaken to establish the efficacy of this oil as an antimicrobial agent against clinical S. epidermidis isolates in planktonic and biofilm cultures. Chlorhexidine, triclosan, and gentamicin were used as positive controls in addition to examination of possible synergistic effects by combining cinnamon oil with any of these clinically used antimicrobials.