Regulation of channel function due to physical energetic coupling with a lipid bilayer.

Regulation of membrane protein functions due to hydrophobic coupling with a lipid bilayer has been investigated. An energy formula describing interactions between lipid bilayer and integral ion channels with different structures, which is based on the screened Coulomb interaction approximation, has been developed. Here the interaction energy is represented as being due to charge-based interactions between channel and lipid bilayer. The hydrophobic bilayer thickness channel length mismatch is found to induce channel destabilization exponentially while negative lipid curvature linearly. Experimental parameters related to channel dynamics are consistent with theoretical predictions. To measure comparable energy parameters directly in the system and to elucidate the mechanism at an atomistic level we performed molecular dynamics (MD) simulations of the ion channel forming peptide-lipid complexes. MD simulations indicate that peptides and lipids experience electrostatic and van der Waals interactions for short period of time when found within each other's proximity. The energies from these two interactions are found to be similar to the energies derived theoretically using the screened Coulomb and the van der Waals interactions between peptides (in ion channel) and lipids (in lipid bilayer) due to mainly their charge properties. The results of in silico MD studies taken together with experimental observable parameters and theoretical energetic predictions suggest that the peptides induce ion channels inside lipid membranes due to peptide-lipid physical interactions. This study provides a new insight helping better understand of the underlying mechanisms of membrane protein functions in cell membrane leading to important biological implications.

Characteristics of norovirus gastroenteritis outbreaks in a psychiatric centre.

Noroviruses are an important aetiological agent of acute gastroenteritis. They are responsible for large outbreaks of disease in the community, hospitals and long-term-care facilities. The clinical manifestations of norovirus outbreaks in psychiatric units are rarely described. The disease burden and impact highlight the importance of timely notification and investigation of these outbreaks. We analysed the characteristics of four norovirus outbreaks which occurred during a 3-year period in an in-patient psychiatric care unit. A total of 184 patients were affected which included 172 hospitalized patients, seven healthcare workers (HCWs) and five psychiatric nursing-home residents. The mean incidence rate of norovirus gastroenteritis (NVG) in hospitalized patients during these outbreaks was 12·7%. These outbreaks were characterized by higher incidence in middle-aged male patients, predominant sickness of diarrhoea, short duration of illness, peaks in late winter and early spring, and higher susceptibility in acute psychiatric patients. HCWs had longer duration of illness than psychiatric patients. More than 10% of affected patients experienced ≥ 2 infections. Infection control measures were instituted and a comprehensive, responsive standard operating procedure for NVG and outbreak management was developed. After implementation of these measures, no further outbreaks of NVG occurred during the study period.

Charge-based interactions of antimicrobial peptides and general drugs with lipid bilayers.

Membrane-active agents (MAAs), such as antimicrobial peptides (AMPs) and chemotherapy drugs (CDs), induce ion pores/channels inside lipid bilayer membrane, as confirmed by standard electrophysiology experiments. A novel experimental method is described which detects agents directly at the membrane as confirmed for MAAs, CDs and aptamers. MAAs exhibit characteristic 'charge based' interactions with lipids. Electrostatic (ES) and van der Waals (vdW) contributions to the interaction energies have been estimated using molecular dynamics (MD) simulations. These results are consistent with the screened Coulomb interaction predictions recently developed for lipid bilayer binding of integral AMP channels. Energy- and distance-dependence of MAA-lipid interactions from MD simulations are represented by universal probability functions. A generalized model of MAA-lipid interactions is developed based on the charge and geometrical profiles of the participating lipids and AMPs. The corresponding driving force correlates directly with the stability of MAA-lipid structures as observed in electrophysiology experiments. We conclude that MAAs and similar agents that target lipid membranes exhibit physiological effects mainly due to ES and vdW interactions determined by their charge profiles.

Dataset on interactions of membrane active agents with lipid bilayers.

We address drug interactions with lipids using in silico simulations and in vitro experiments. The data article provides extended explanations on molecular mechanisms behind membrane action of membrane-active agents (MAAs): antimicrobial peptides and chemotherapy drugs. Complete interpretation of the data is found in the associated original article 'charge-based interactions of antimicrobial peptides and general drugs with lipid bilayers' [1]. Data on molecular dynamic simulations of the drug lipid complexes are provided. Additional data and information are provided here to explain the connectivity among various information and techniques used for understanding of the membrane action and/or binding of MAAs including aptamers. Brief explanation has been provided on the possibility of achieving a converted triangle from newly discovered quadrangle, sides of which explain four different phenomena: 'membrane effects', 'detection and quantification', 'origin of energetics' and 'structure stability' while drug effects occur. Triangle or quadrangle corners represent various techniques that were applied.

Ultrastructural changes of posterior lingual glands after hypoglossal denervation in hamsters.

Posterior lingual glands consist of two sets of minor salivary glands that serve important functions in oral physiology. To investigate the hypothesis that the hypoglossal nerve provides sympathetic innervation to the posterior lingual glands, we examined ultrastructural changes in the glands following hypoglossal denervation. In the posterior deep lingual glands (of von Ebner), the serous acinar cells showed a decrease in the number of secretory granules and an increase in lipofuscin accumulation. The ratios of cells containing lipofuscin granules were 11.39, 36.49 and 50.46%, respectively, of the control, 3- and 7-day post-axotomy glands (P < 0.001). Intraepithelial phagocytotic activity was increased. The mucous acinar cells in the posterior superficial lingual glands (of Weber) also showed degenerative changes after hypoglossal denervation. One week after nerve transection, marked cytoplasmic vacuolation and fragmentation of organelles were frequently observed. Degenerative changes were also found in unmyelinated axons associated with the glands. We provide the first evidence of the structural and functional connections between the sympathetic component of the hypoglossal nerve and posterior lingual glands.

Formation of morphine from codeine in Chinese subjects of different CYP2D6 genotypes.

Codeine and morphine pharmacokinetics among different CYP2D6 genotypes was compared in this study. Polymerase chain reaction tests were used to determine CYP2D6 genotypes in leukocyte deoxyribonucleic acid in 32 unrelated volunteers. Based on the genotypes, subjects were categorized into three groups: homozygous C/C188 (n = 8), heterozygous C/T188 (n = 12), and homozygous T/T188 (n = 12). Each subject was given a single oral dose of 30 mg codeine phosphate tablet after overnight fasting. Plasma concentration of codeine and 24-hour urinary morphine recovery were measured with HPLC. All three genotypes of subjects showed almost identical time profiles of plasma codeine. Urinary morphine glucuronide was hydrolyzed with beta-glucuronidase. The total recovered amount of morphine and glucuronides was 4349 +/- 646, 2564 +/- 242, and 1127 +/- 164 nmol (mean +/- SEM), respectively, for C/C188, C/T188, and T/T188 subjects (p < 0.05). The significant lower amount of urinary morphine but identical codeine plasma concentration suggested a lower partial clearance of the formation of morphine from codeine in T/T188 subjects. The results suggest a future study to assess the analgesic effect of codeine in different genotypes of CYP2D6 extensive metabolizers.

An empirical comparison of lead exposure pathway models.

Structural equation modeling is a statistical method for partitioning the variance in a set of interrelated multivariate outcomes into that which is due to direct, indirect, and covariate (exogenous) effects. Despite this model's flexibility to handle different experimental designs, postulation of a causal chain among the endogenous variables and the points of influence of the covariates is required. This has motivated the researchers at the University of Cincinnati Department of Environmental Health to be guided by a theoretical model for movement of lead from distal sources (exterior soil or dust and paint lead) to proximal sources (interior dust lead) and then finally to biologic outcomes (handwipe and blood lead). The question of whether a single structural equation model built from proximity arguments can be applied to diverse populations observed in different communities with varying lead amounts, sources, and bioavailabilities is addressed in this article. This reanalysis involved data from 1855 children less than 72 months of age enrolled in 11 studies performed over approximately 15 years. Data from children residing near former ore-processing sites were included in this reanalysis. A single model adequately fit the data from these 11 studies; however, the model needs to be flexible to include pathways that are not frequently observed. As expected, the more proximal sources of interior dust lead and handwipe lead were the most important predictors of blood lead; soil lead often had a number of indirect influences. A limited number of covariates were also isolated as usually affecting the endogenous lead variables. The blood lead levels surveyed at the ore-processing sites were comparable to and actually somewhat lower than those reported in the the Third National Health and Nutrition Examination Survey. Lessened bioavailability of the lead at certain of these sites is a probable reason for this finding.

Comparison of susceptibility to extended-spectrum beta-lactam antibiotics and ciprofloxacin among gram-negative bacilli isolated from intensive care units.

The in vitro activities of extended-spectrum beta-lactam antibiotics (including piperacillin, cefotaxime, ceftriaxone, ceftazidime, cefepime, imipenem, and meropenems) were assessed and compared with the activity of ciprofloxacin against 366 clinical Gram-negative bacilli isolates from the intensive care units of Taichung Veterans General Hospital. The most prevalent species isolated were Pseudomonas aeruginosa and Acinetobacter baumannii. The activities of ceftazidime, cefepime, imipenem, and meropenem against these isolates were comparable to that of ciprofloxacin. Meropenem was found to be the most potent extended-spectrum beta-lactam antibiotic tested and the MIC50s and MIC90s for most of these multiresistant strains were lower than those of imipenem, ceftazidime, and cefepime, except for Stenotrophomonas maltophilia. The extended-spectrum beta-lactam antibiotics that were still active against S. maltophilia were piperacillin and ceftazidime. More than 50% of Enterobacter spp. were resistant to third-generation cephalosporins and piperacillin, but they remained susceptible to carbapenems and cefepime.

DNA fingerprinting of Pseudomonas aeruginosa serotype O11 by enterobacterial repetitive intergenic consensus-polymerase chain reaction and pulsed-field gel electrophoresis.

We report the use of pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus (ERIC)-based polymerase chain reaction (PCR) to characterize clinical isolates of Pseudomonas aeruginosa serotype O11 collected from an incident of hospital-acquired infection. Both typing techniques differentiated 20 different strain types among seven epidemiologically related isolates and 22 epidemiologically unrelated isolates. There was complete concordance between these two techniques. Our results indicate that the ERIC-based PCR technique represents a rapid and simple means for typing P. aeruginosa serotype O11 with a level of discrimination equivalent to that of PFGE.

Comparison of detection of extended-spectrum beta-lactamases by agar dilution method, E-test ESBL screen and double disk test.

The extended-spectrum beta-lactamases (ESBL) are derived from TEM-or SHV-enzymes. They mediate resistance to broad-spectrum beta-lactams and can cause infectious outbreaks in hospitals. Rapid recognition and diagnosis are important for the clinician to prescribe more effective treatment. In the present study, a group of 52 probable ESBL-producing Klebsiella pneumoniae and Escherichia coli having a suspected resistant antibiogram phenotype were included. The E-test ESBL screen and the double disk test were performed for these isolates for detection of ESBL-producing strains, as compared with the conventional agar dilution method. The agreement between the E-test ESBL screen or the double disk test and the conventional agar dilution method was good and the degree of agreement were 86.5% and 92.3% respectively. The results showed that both the E-test ESBL screen and the double disk test were useful and convenient for detection of ESBLs.

Frontal cephalometric study of dentofacial morphology in children with bilateral clefts of lip, alveolus and palate.

The transverse dentofacial morphology of 36 children with bilateral cleft lip, alveolus and palate was studied by means of a frontal proportional cephalometric analysis at the ages of three, eight and twelve years. Comparison of the variables of the cleft group was made with the normal dimensions as obtained from the Bolton cephalometric templates. The results indicated that the BCLP group presented characteristics and significant differences from the normal in the dimensions of the nasal septum width and the mandibular intergonial width as they are both related to the interorbital width, the maxillary intermolar width as it is related to the mandibular intermolar width and the maxillary width as it is related to the mandibular intergonial width at all three ages. The maxillary base and intermolar widths, although significantly different at the ages of three and eight years, showed no significant deviation from normality at the age of twelve years. Following orthodontic treatment between the ages of seven to twelve years, the maxillary intermolar width of the treated subgroup was significantly larger than in the untreated subjects.

Comparison of immunogenicity of simultaneous and nonsimultaneous vaccination with MMR and JE vaccine among 15-month-old children.

To evaluate the immunogenicity of measles- mumps- rubella (MMR) vaccination with Japanese encephalitis (JE) vaccine nonsimultaneously and simultaneously, 145 babies, aged 15 months were enrolled into two groups. Group A received MMR and JE vaccines nonsimultaneously at an interval of 6 weeks; group B received the vaccinations simultaneously. Antibody titers of MMR and JE were detected before and 8 weeks after vaccination. A total of 118 babies (61 in group A; 57 in group B) completed the study. In group A, mean increments of logarithmic geometric mean titers (GMTs) of MMR and JE were 4.51, 5.93, 4.07 and 1.99; seroresponse rates were 100% (61/61), 77.05% (47/61), 96.72% (59/61) and 59.02% (36/61) respectively. In group B, mean increments of logarithmic GMTs of MMR and JE were 4.35, 5.37, 4.44 and 1.93; seroresponse rates were 98.25% (56/57), 77.19% (44/57), 98.25% (56/57) and 57.89% (33/57) respectively. There were no significant differences between these two groups. These results suggest that simultaneous and nonsimultaneous vaccination with MMR and JE vaccines were similar in immunogenicity.

Effects of Tremella mesenterica on steroidogenesis in MA-10 mouse Leydig tumor cells.

Tremella mesenterica (TM), a yellow jelly mushroom, has been traditionally used as food and crude medicine to improve several kinds of symptoms in Chinese society for a long time. Recent studies have illustrated that the fractions of fruiting bodies of TM exhibit a significant hypoglycemic activity in diabetic mouse models, which usually suffer from sexual dysfunction. In a previous study, we showed that TM reduced plasma testosterone production in normal rats without any positive effect in diabetic rats. It evolved a question of TM directly regulating Leydig cell steroidogenesis. In this study, MA-10 mouse Leydig tumor cells were treated with vehicle, different dosages of TM with or without human chorionic gonadotropin (hCG 50 ng/ml) to clarify the effects. Results showed that TM at different dosages (0.01-10 mg/ml) did not have any effect on MA-10 cell steroidogenesis (p > 0.05). In the presence of hCG, there was an inhibitory trend that TA suppressed MA-10 cell progesterone production at 3 hr treatment with a statistically significant difference by the 10 mg/ml TM (p < 0.05). In time course effect, TM alone did not have any effect on MA-10 cell steroidogenesis from at 1, 2, 3, 6 and 12 hr (p > 0.05). However, TM did reduce hCG-treated MA-10 cell progesterone production at 1, 2 and 3 hr (p < 0.05), respectively. To determine whether TM would have adverse effects on MA-10 cell steroidogenesis in the presence of hCG, MTT assay and recovery studies were conducted. MTT assay indicated that TM had no effect on surviving cells. In addition, with the removal of TM, and then the addition of hCG (2 and 4 hr), progesterone levels were restored within 4 hr. Taken together, present studies suggested that TM suppressed hCG-treated steroidogenesis in MA-10 cells without any toxicity effect.

IgE-binding epitopes of the American cockroach Per a 3 allergen.

BACKGROUND: The Per a 3 is a species-specific allergen of the American cockroach (Periplaneta americana) related to insect hemolymph proteins and includes four known isoallergens. This study aimed to identify Per a 3 linear IgE-binding epitopes. METHODS: Per a 3 recombinant fragments were generated from the recombinant Per a 3.01 allergen (685 amino acid residues) by using existing restriction sites or by using polymerase chain reaction products, and expressed in Escherichia coli. Antigenicities were assessed by immunoblotting, enzyme-linked immunosorbent assay (ELISA), and binding inhibition with human IgE. RESULTS: Human IgE recognized recombinant fragments 340-425, 466-579, 502-595, and 595-636 as revealed by immunoblotting and ELISA. On the other hand, the N-terminal fragment 1-399, recombinants 410-443, 472-551, 502-579, 606-636, and the C-terminal fragment 636-685 were unable to bind human IgE. Amino acid sequences 400-409, 466-471, 580-595, and 595-605 were shown to be required for IgE binding to the Per a 3.01 allergen, suggesting that the C-terminus contains most of the IgE-binding sites. Four peptides corresponding to these IgE-binding amino acid sequences were synthesized. These peptides reacted with most sera (62.5-87.5%) tested as revealed by ELISA, demonstrating a heterogeneous IgE-binding response. Moreover, preincubation of IgE-positive recombinant proteins and synthetic peptides with atopic IgE resulted in marked inhibition of the IgE binding to Per a 3.01 allergen. Amino acid sequences 400TVLRDPVFYQ409, 466NNVDQI471, 580VDKGHNYCGYPENLLI595, and 595IPKGKKGGQAY605 of the major recombinant American cockroach Per a 3.01 allergen were involved in IgE binding. CONCLUSION: These findings will advance our understanding of the antigenic structures responsible for allergenicity to the American cockroach, thereby providing strategies for the development of immunotherapies.

An electron microscopical study of epiplexus and supraependymal cells in the prenatal rat brain following a maternal injection of 6-aminonicotinamide.

Epiplexus and supraependymal cells in the lateral ventricles of both normal and experimental prenatal rats were studied with the scanning and transmission electron microscopes. In normal rats, the epiplexus cells, which were predominantly spindle shaped, displayed long filopodial processes inserted into the palisade of microvilli of the choroid epithelium; their cell bodies appeared relatively smooth with occasional blebs. In experimental animals in which the mother was given an injection of 6-aminonicotinamide (6-AN), the cell bodies of the epiplexus cells became extremely ruffled or blebbed. They were seen to be actively involved in the phagocytosis of leaked erythrocytes. The behaviour of supraependymal cells was rather similar. When stimulated by a 6-AN injection, the cells showed large prominent blebs and they too were engaged in phagocytic activity. It was concluded from this study that intraventricular macrophages bearing numerous filopodia are the less active cells whereas those bearing shorter processes, in particular, blebs or ruffles, represent the active form.

Translation drag coefficient of a self-similar assembly of spheres immersed in an incompressible fluid.

On the basis of deterministic fractals and the Rotne-Prager hydrodynamic interaction tensor, we confirm the asymptotic as well as the finite size scaling of the friction coefficient lambda of a self-similar structure. The fractal assembly is made of N spheres with its dimension varying from D < 1 to D = 3. The number of spheres can be as high as N approximately O(10(4)). The asymptotic scaling behavior of the friction coefficient per sphere is lambda approximately N(1/D-1) for D > 1, lambda approximately (lnN)(-1) for D = 1, and lambda approximately N(0) for D < 1. The crossover behavior indicates that while in the regime of D > 1 the hydrodynamic screening effect grows with the size, for D<1 it is limited in a finite range, which decays with decreasing D.

Clinical correlates of quantitative acoustic analysis in ataxic dysarthria.

The speech of 15 Taiwanese patients with cerebellar dysfunction and ataxic dysarthria was investigated utilizing techniques of acoustic analysis and instrumental measurement. Semiquantitative assessment of cerebellar function (SQACF) was also performed. The results of the acoustic analysis of the cerebellar speech were then correlated with the findings in the SQACF. The overlapping of voice onset time highly correlates with truncal ataxia as well as eye movement abnormality and eye-hand coordination. The prolongation of vowel duration also correlates significantly with tandem walking, dysdiadochokinesia and eye movement abnormality. The correlation of the speech function with other cerebellar motor functions provides further insight into the functional anatomy for cerebellar speech motor control. This study concludes that the midline structures-vermis and fastigial nucleus-seem to be the primary focus for the coordination of motor speech in the cerebellum.

Fine structural changes in the hamster pineal gland after blinding and superior cervical ganglionectomy.

Pineal glands of male hamsters 8 weeks after removal of both eyes or both superior cervical ganglia and those of untreated animals were studied by electron microscopy. In the blinded hamsters the reproductive organs were remarkably involuted, whereas the pinealocytes enlarged and were characterized by a tremendous hypertrophy of the smooth-surfaced endoplasmic reticulum, in the mesh of which some dense cored vesicles were distributed. In constrast the pinealocytes of ganglionectomized hamsters atrophied and were noted by a large number of lysosomes and sparsity of the agranular reticulum, the testes being significantly larger than the controls. The findings were interpreted to be compatible with the view that the pineal capability of producing antigonadal substance is augmented by blinding and is suppressed by cervical ganglionectomy due to the impairment of normal functioning of the pineal by denervation. It is assumed that the degree of development of the smooth endoplasmic reticulum in the pinealocyte is parallel to, and reflects that of the pineal activity. Probably the membranous organelle is involved in the elaboration of the pineal antigonadal substance.

Scanning electron microscopy of amoeboid microglial cells in the transient cavum septum pellucidum in pre- and postnatal rats.

The cavum septum pellucidum in rats of different ages was studied by light and scanning electron microscopy. A reconstruction from serial paraffin sections showed that the cavum was a pyramidal shaped closed cavity which was bounded above by the corpus callosum and inferolaterally by the lateral septal nuclei. The first sign of the cavum formation was noted in the 20 days post conception rat where there was a loosening up of the neuropil beneath the corpus callosum deep to the longitudinal fissure. A variable number of amoeboid microglial cells, characterised by their abundant eosinophilic cytoplasm, was seen among the smaller immature cells in the wide interstitial spaces. A definitive cavity was formed in the 21 days post conception rat and it continued to grow until the fifth postnatal day when it gradually diminished in size to become slit-like by the fifteenth postnatal day. The scanning electron microscope showed that the wall of the cavum was composed of a feltwork of glial and nerve fibres. Two types of cells were present in the cavum: cells identified as glioblasts, and amoeboid microglial cells. The glioblasts were were characterised by having a smooth cell body with radiating long processes. The amoeboid microglial cells showed diverse forms of surface protrusions: blebs, filopodia and membrane ruffles similar to other tissue macrophages. They were either adherent to the walls of the cavum, clustered around the blood vessel which traversed the cavum, or floating freely in the lumen. It was suggested that the amoeboid microglial cells were probably derived from extravasated blood monocytes in response to the physical damage resulting from the formation of the cavum septum pellucidum in the developing brain.