Blockage of amyloid beta peptide-induced cytosolic free calcium by fullerenol-1, carboxylate C60 in PC12 cells

Amyloid beta protein (Abeta) alters signal transduction systems, including increases in the cytosolic free calcium ([Ca2+]i) response which have pathophysiological significance in Alzheimer's disease (AD). The purposes of this study were to elucidate the mechanism involved in Abeta's effect on the Ca2+ signal and to evaluate the effect of fullerenol-1, a water-soluble hydroxyl and superoxide radical scavenger, on the Abeta-induced Ca2+ response. Both Abeta and bradykinin (BK) dose-dependently elevated [Ca2+]i in PC12 cells. Fullerenol-1, at a concentration range between 100 nM and 1 microM, dose-dependently reduced the Abeta-induced [Ca2+]i response, but did not alter the subsequent BK-mediated process. Thapsigargin, an inhibitor of Ca2+-ATPase, released Ca2+ from the internal store and diminished the BK-mediated calcium spike but did not affect the Abeta-induced Ca2+ response. In the absence of extracellular calcium, the Abeta-induced, but not BK-induced, calcium spike was completely abolished. The Ca induced by Abeta did not enter through the voltage-dependent calcium channels or ligand gated calcium channels, because the peak of Abeta-evoked Ca2+ was not significantly altered by various Ca2+ channel blockers or a NMDA receptor antagonist MK801. In addition, neither cholera toxin nor pertussis toxin altered the Abeta-induced Ca response. The results demonstrated that Abeta-stimulated [Ca2+]i increase is due to Ca influx from an extracellular source rather than from the intracellular store. Alteration of the membrane lipid structure and permeability by free radicals generated by Abeta may be a major cause of Ca -influx. Furthermore, fullerenol-1, a novel antioxidant, may provide therapeutic benefits in neurodegenerative diseases such as AD.

Finite element analysis of brain contusion: an indirect impact study

The mechanism of brain contusion has been investigated using a series of three-dimensional (3D) finite element analyses. A head injury model was used to simulate forward and backward rotation around the upper cervical vertebra. Intracranial pressure and shear stress responses were calculated and compared. The results obtained with this model support the predictions of cavitation theory that a pressure gradient develops in the brain during indirect impact. Contrecoup pressure-time histories in the parasagittal plane demonstrated that an indirect impact induced a smaller intracranial pressure (-53.7 kPa for backward rotation, and -65.5 kPa for forward rotation) than that caused by a direct impact. In addition, negative pressures induced by indirect impact to the head were not high enough to form cavitation bubbles, which can damage the brain tissue. Simulations predicted that a decrease in skull deformation had a large effect in reducing the intracranial pressure. However, the areas of high shear stress concentration were consistent with those of clinical observations. The findings of this study suggest that shear strain theory appears to better account for the clinical findings in head injury when the head is subjected to an indirect impact.

In vivo and in vitro natural frequency analysis of periodontal conditions: an innovative method

BACKGROUND

When measuring periodontal disease, various types of equipment for making objective measurements of tooth mobility have been proposed. However, these devices and methodology are insufficient in terms of reliability. An innovative method using vibrational theories to assess the periodontal attachment level of natural teeth is presented in this study.

METHODS

Modal testing technique, a non-destructive and time-saving method, was used for non-invasive and quantitative measurement of the natural frequencies of the upper central incisor in vivo and in vitro. A finite element model was established, and modal testing experiments were simulated to assess the relationship between bone level and teeth.

RESULTS

The first dominant natural frequency of healthy human upper central incisors ranges from 710 Hz to 3,360 Hz, with an average of 1,701+/-679 Hz. Both in vitro experiment and finite element simulation showed that lowering of the attachment level causes a significant decrease in the natural frequencies, and a strong relationship (r = -0.99, P <0.01) was observed between the frequency and the bone level height.

CONCLUSIONS

Our results suggested that natural frequency is an important parameter for assessing the periodontal condition and that the modal testing technique is a useful supplemental method for assessing the attachment conditions of the periodontium.

Antioxidants prevent amyloid peptide-induced apoptosis and alteration of calcium homeostasis in cultured cortical neurons

Beta-amyloid ((A)beta) is a peptide of 39-42 amino acids that is the primary component of plaques in Alzheimer's disease (AD). The mechanism by which (A)beta expresses its neurotoxic effects may involve induction of reactive oxygen species (ROS) and elevation of intracellular free calcium levels. Cultured cortical cells were utilized to study the alterations in calcium homeostasis underlying the neurotoxic effect of (A)beta. Serum supplement B27 and vitamin E were effective in preventing neuronal death as assessed by lactate dehydrogenase (LDH) release, (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and number of apoptotic nuclei. In addition, (A)beta-induced cytosolic free calcium ([Ca2+]i) was blocked by antioxidants vitamin E and U83836E, but not by N-methyl-D-aspartic acid (NMDA) receptor antagonist MK-801, or by voltage-gated calcium channel blocker nimodipine. Taken together, the results suggest that NMDA receptor and voltage-gated calcium channels are not involved in (A)beta-induced [Ca2+]i increase. This increase appeared to be the result of extracellular calcium influx by some unknown mechanisms. In addition, antioxidants such as B27 were effective in protecting cultured cortical neurons against (A)beta, and correlated with (A)beta attenuation of early calcium response.

Microcalorimetric studies of interactions between proteins and hydrophobic ligands in hydrophobic interaction chromatography: effects of ligand chain length, density and the amount of bound protein

Using isothermal titration calorimetry (ITC), this investigation directly measured the adsorption enthalpies of proteins on various hydrophobic adsorbents. Various amounts of butyl and octyl groups were attached onto CM-Sepharose to form C4 and C8, two types of hydrophobic adsorbents. The adsorption enthalpies of both trypsinogen and alpha-chymotrypsinogen A were measured at 4.0 M NaCl and pH 10.0, in which most ionic interaction was suppressed. The adsorption isotherms of both proteins on various adsorbents were also measured, thus allowing us to calculate the Gibbs free energy and entropy of adsorption. Experimental results indicated that the adsorption of both proteins on butyl-containing adsorbents was exothermic, while their adsorption on octyl ones was endothermic. In addition, binding of both proteins with the butyl ligand is basically an adsorption process, while binding with the octyl ligand is adsorption and partition processes. Moreover, on both butyl or octyl, the adsorption enthalpy became increasingly positive as the ligand density increased, while the adsorption entropy became more positive as the alkyl chain length or density of the adsorbent increased. In addition, ITC was used to measure protein-protein interaction. The adsorption enthalpy of both proteins increased as the amount of bound protein increased, and the enthalpy increase of trypsinogen appeared to be higher than that of alpha-chymotrypsinogen A. This observation implies that protein-protein repulsion was stronger among trypsinogen molecules in the experiments.

Synthesis of biotinylated glyfoline for immunoelectron microscopic localization

Antineoplastic glyfoline (1) has potent antitumor efficacy against various murine and human solid tumors. To elucidate the actual mechanism of action, we synthesized biotinylated glyfoline (B-Gly) and used it for the visualization of glyfoline-binding sites in nasopharyngeal carcinoma (NPC) cells. Under the electron microscope (EM), after cells were incubated for 6-36 h, the reaction products of anti-B-Gly were seen on some areas of the external cell surface and on the outer and inner membranes of the mitochondria. Pure EM morphology of NPC cells after glyfoline treatment revealed the similar morphological change of mitochondria. These findings indicate that the binding site of glyfoline in NPC is the inner membrane of the mitochondria, suggesting that B-Gly can be used as a marker for glyfoline localization.

ATP-stimulated c-fos and zif268 mRNA expression is inhibited by chemical hypoxia in a rat brain-derived type 2 astrocyte cell line, RBA-2

The stimulus-transcriptional coupling during ischemia/hypoxia was examined for ATP-stimulated expression of immediate early genes (IEGs; c-fos, zif268, c-myc and nur77) in a rat brain-derived type 2 astrocyte cell line, RBA-2. Incubation of cells with 1 mM of extracellular ATP stimulated time-dependent expression of c-fos and zif268. ATP induced the largest increases in zif268 mRNA and a lesser one in c-fos mRNA. ATP also induced a slight increase in nur77 mRNA but was ineffective in inducing c-myc expression in these cells. Brief exposure of cells to potassium cyanide to simulate chemical hypoxia induced 9-fold and 7-fold transient increases in c-fos and zif268 expression, respectively, but did not affect c-myc or nur77 expression. When cyanide and ATP were added together, the expression of c-fos and zif268 expression was inhibited, and the effect was mimicked by simulating chemical hypoxia with sodium azide. To elucidate the mechanism involved, the effect of cyanide on ATP-stimulated increases in intracellular Ca(2+) concentrations, [Ca(2+)](i), and phospholipase D (PLD) activities were measured. Cyanide induced an increase in [Ca(2&plus);](i) and further enhanced the ATP-stimulated increases in [Ca(2+)](i) and PLD activities. Nevertheless, metabolic inhibitor, iodoacetate, blocked the ATP-induced c-fos and partially inhibited zif268 expression, and deprivation of cells with glucose also inhibited the ATP-induced c-fos expression. Taken together, these results demonstrate that both extracellular ATP and chemical hypoxia induce c-fos and zif268 expression in RBA-2 type 2 astrocytes. The chemical hypoxia inhibited ATP-stimulated c-fos and zif268 expression is not due to alterations in Ca(2+) and PLD signaling, and is at least partially related to metabolic disturbance in these cells.

Determination of catecholamines in pheochromocytoma cell (PC-12) culture medium by microdialysis-microbore liquid chromatography

An in vitro microdialysis system was constructed for the measurement of catecholamines in pheochromocytoma cell culture medium. The novel microdialysis device is composed of a petri dish, a dialysis membrane and two transmission tubes. The dialysis membrane is located in the space of a petri dish such that it is immersed in the culture medium. Catecholamines contained in the culture medium diffused into a designed dialysis membrane with sufficient recovery (about 60%). Dialysates were collected by a sampling loop and introduced by an on-line injector to a microbore liquid chromatographic system for analysis of catecholamines. This assay yielded a detection limit of 0.2-0.5 pg/injection with acceptable intra- and inter-assay reproducibilities in 5 microl of dialysates. To evaluate the on-line microdialysis system, PC-12 cells were cultured in a petri dish within an incubator. The baseline concentration of dopamine in PC-12 cell culture medium was about 0.29 ng/ml which was elevated to 2.43 ng/ml after treatment with 0.5 mM potassium cyanide. In conclusion, the present microassay provides for the sensitive, direct measurement of catecholamines in culture medium while minimizing pretreatment procedures for sample preparation.

Amyloid beta peptide impaired carbachol but not glutamate-mediated phosphoinositide pathways in cultured rat cortical neurons

Signal transduction systems, including cholinergic pathways, which are likely to be of pathophysiological significance are altered in Alzheimer's disease (AD). Muscarinic cholinergic receptors are linked to the hydrolysis of phosphoinositide, involving the production of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and the mobilization of cytosolic free calcium concentrations ([Ca2+]i). Effects of amyloid peptide (A(beta)) on these signals prior to neuronal degeneration were examined in cultured rat cortical cells. A(beta) increased the release of lactate dehydrogenase (LDH) in a concentration-dependent manner, however, it was blocked by B27 supplement. Prolonged exposure to a sublethal dose of A(beta) 25-35 or 1-42 disrupted carbachol-mediated release of Ins(1,4,5)P3 and [Ca2+]i, which was inhibited in media supplemented with B27 or the antioxidant vitamin E. In order to determine the specificity of the effect of A(beta), various agonists glutamate or KCl but not bradykinin which utilize the phosphoinositide cascade were investigated. Our results indicated that A(beta) did not affect the stimulation of glutamate or KCl-mediated production of Ins(1,4,5)P3 or cause elevation in [Ca2+]i. Furthermore, metabotropic agonist trans-1-amino-cyclopentane-1,3,-dicarboxylate (ACPD) elevated calcium level was not inhibited by A(beta) pre-treatment. Taken together, the results demonstrate that a sublethal dose of A(beta) selectively impaired cholinergic receptor-mediated signal transduction pathways, and antioxidant or B27 supplement attenuated this effect of A(beta). Alterations of cholinergic signaling by prolonged exposure to A(beta) could be involved in cortical neurodegeneration that occurs in AD. Because functional loss of cholinergic pathways is an important aspect of AD, the differences in susceptibility of these two types of receptors prior to other signs of A(beta) action is important and requires further investigation.

Cytokine receptor common beta chain as a potential activator of cytokine withdrawal-induced apoptosis

Growth factors and cytokines play an important role in supporting cellular viability of various tissues during development due to their ability to suppress the default cell death program in each cell type. To date, neither the triggering molecule nor the transduction pathway of these default apoptosis programs is understood. In this study, we explored the possibility that cytokine receptors are involved in modulating cytokine withdrawal-induced apoptosis (CWIA) in hematopoietic cells. Expression of the exogenous cytokine receptor common beta chain (betac), but not the alpha chains, accelerated CWIA in multiple cytokine-dependent cell lines. Reduction of the expression level of endogenous betac by antisense transcripts resulted in prolonged survival during cytokine deprivation, suggesting a critical role of betac in modulating CWIA. Fine mapping of the betac subunit revealed that a membrane-proximal cytoplasmic sequence, designated the death enhancement region (DER), was critical to the death acceleration effect of betac. Furthermore, DER accelerated cell death either as a chimeric membrane protein or as a cytosolic protein, suggesting that DER functions independently of the cytokine receptor and membrane anchorage. Cross-linking of the chimeric membrane-bound DER molecules by antibody or of the FK506-binding protein-DER fusion protein by a synthetic dimerizing agent, AP1510, did not abrogate the death acceleration effect. Transient transfection assays further indicated that DER promoted cell death in the absence of serum in the nonhematopoietic 293 cell line. In summary, our data suggest that betac plays an important role in modulating CWIA via an anchorage-independent and aggregation-insensitive mechanism. These findings may facilitate further studies on the signaling pathways of CWIA.

Three-dimensional finite element analysis of subdural hematoma

BACKGROUND

Head motion, an important factor in acute subdural hematoma (ASDH), can be broken down into translational and rotational elements. We used three-dimensional finite element analysis to examine the thresholds of angular and tangential acceleration required to tear bridging veins in humans during head impact.

METHODS

The lengths of midsagittal and parasagittal bridging veins were calculated first. To assess the effect of translational and rotational acceleration, the strain of each vein was then computed under three different motions. The threshold of ASDH was expressed in terms of tangential and rotational acceleration.

RESULTS

Deformation-angle histories of the midsagittal and parasagittal bridging veins showed that veins that drain forward into the superior sinus at a 130-degree angle incurred the greatest stretch strain during occipital impact. In the midsagittal plane, pure rotation induced greater stretch strain on these veins (14.4%) than pure translation (2.5%) or combined translation and rotation motion (10.4%). A tangential acceleration of 3,912.9 G or an angular acceleration of 71.2 krad/s2 seemed to approximate the threshold for ASDH in the human midsagittal plane, whereas 5,010.9 G and 97.4 krad/s2 approximated the threshold in the parasagittal plane.

CONCLUSION

Impact direction and orientation of bridging veins are both important factors in ASDH. Threshold criteria for ASDH can be expressed in terms of tangential and rotational acceleration.

Effects of ear type, sex, age, body weight, and climate on temperatures in the external acoustic meatus of dogs

OBJECTIVE

To investigate effects of ear type, sex, age, body weight, and ambient climatic conditions on external acoustic meatus (external ear canal) temperatures in dogs.

ANIMALS

650 dogs without clinical signs of ear disease.

PROCEDURE

Dogs were assigned to 5 groups on the basis of auricular conformation and amount of hair in the external ear canal and 4 groups on the basis of body weight or age. External ear canal temperatures (EECT) were measured, using an infrared thermometer. Mean EECT determined for each group were compared to evaluate effects of ear type, age, weight, and sex, and EECT measured at different ambient temperatures and humidities were compared to determine climatic effects.

RESULTS

Dogs with hirsute ear canals had significantly lower EECT than dogs with hairless ear canals, whereas significant differences were not detected between dogs with erect and pendulous auricles. Dogs < 6 years old had higher EECT than older dogs, and dogs that weighed < 6 kg had lower EECT than larger dogs. External ear canal temperatures measured when ambient temperatures were < 25 C were less than those measured at warmer temperatures. Sex and relative humidity did not affect EECT CONCLUSIONS AND CLINICAL RELEVANCE: EECT of dogs without ear disease were affected by weight and age, amount of hair in the external ear canal, and ambient temperature. However, hirsute ears had lower, not higher, EECT than hairless ears, suggesting that EECT may play less of a role in the development of otitis externa than believed.

Hair concentrations of calcium, iron, and zinc in pregnant women and effects of supplementation

In this investigation, the concentration levels of hair elements of calcium, iron, and zinc were measured in pregnant women from Tianjin metropolis, China. The subjects were 93 cases of pregnant women who had been suffering from calcium, iron, or zinc deficiency judged by blood tests at the mid-term of the second trimester or early in the third trimester. Of these 93 cases, 82 subjects had their hair element levels measured when the blood tests were conducted. Then, they were supplied with mineral element nutrients of gluconic acidic zinc (noted as Zn-nutrient), gluconic acidic calcium (Ca-nutrient), or/and ferrous sulfate (Fe-nutrient) which were correspondent to the deficient element(s) for more than 2 mo before 84 subjects returned to hospital for further diagnoses and had their hair element levels measured for the second time. Finally, in the third trimester or near-parturient phase, 13 subjects had their hair element levels measured again. Except for the deficiencies of calcium, iron, or/and zinc, these subjects were all healthy without symptoms of any diseases. The concentrations of hair Ca, Fe, and Zn were measured by X-ray fluorescence (XRF) spectrometry. These concentrations of the three hair elements measured at three different times were statistically analyzed. From the analyses, it was clear that hair concentrations of Ca, Fe, and Zn could reflect the effects of supplementation. Also, the mutual resistant effects among Ca-, Fe-, and Zn-nutrients were revealed. However, by appropriate combination, the mutual resistant effects could be depressed and mutual promotional effects might be enhanced. Finally, it could be concluded that mineral element deficiencies might be convalesced by adequate compensations of mineral element nutrients.

Hair and serum calcium, iron, copper, and zinc levels during normal pregnancy at three trimesters

The hair and serum levels of calcium, iron, copper, and zinc levels were measured in a group of 70 healthy pregnant women and in 66 age-matched healthy controls living in the Tianjin city of the People's Republic of China. The study subjects were classified into three subgroups according to gestational age. The hair concentrations were measured by X-ray fluorescence spectrometry, whereas those in sera were established by atomic absorption spectrometry. The hair concentrations of Ca, Fe, Cu, and Zn in the three groups of gravida were lower or significantly lower than those in controls. In sera, the differences did not show statistical significance in most cases. A deficiency of calcium was observed in subjects in the last trimester of gestation. This reinforces the importance of supplementation with calcium during pregnancy.

[Construction of expressing vector for phage display scFv and a mouse unspecified antibody library]

The display of antibody gene library on the surface of E. coli filamentous phage offers a new method of obtaining antibodies against specific antigens. In the paper, it is reported that a phagemid for phage display antibody, named after pFUW80, characterized expressing scFv either secretly or stickily. With a series of designed PCR primers, heavy-chain and light-chain variable region genes of mice antibodies were amplified and a mouse unspecified single-chain antibody library with the size of 1.2 x 10(6) clones was constructed. From this library, phage was selected out against antigen human IgG and detected by ELISA and partial sequence analysis. These primary results established the foundation for future research using this system.

Selective subcellular redistributions of protein kinase C isoforms by chemical hypoxia

The mechanisms of neuronal degeneration following hypoxia/ischemia remain undefined, but the processes include increases in neurotransmitter release, elevation of cytosolic-free calcium concentration, and changes in signal transduction pathways. Activation of the multigene family of protein kinase C (PKC) has been associated with the release of neurotransmitter and the survival of neurons. Therefore, to understand which PKC isozymes are involved in hypoxia/ischemia-induced neuronal degeneration, we examined PKC isozymes after chemical hypoxia (i.e., KCN exposure) in PC12 cells. Cell toxicity, as measured by lactate dehydrogenase (LDH) release, was increased significantly by KCN in glucose-free DMEM and was exaggerated by acute 12-O-tetradecanoyl phorbol-13-acetate (TPA) pretreatment. Under parallel conditions, KCN elevated cytosolic-free calcium ([Ca2+]i) in glucose-free but not in glucose containing DMEM, and TPA pretreatment did not exaggerate KCN's effect on [Ca2+]i. Thus, increases in [Ca2+]i are not sufficient for the synergistic toxic effect of KCN and TPA. In the glucose-free DMEM, selective PKC isozyme inhibitor Go 6976 at 10 nM completely inhibited KCN-induced LDH release and at higher concentrations (1 microM) inhibited the basal levels of LDH release. The protein levels of PKCs in the nuclear, membrane, and cytosolic fractions were measured by Western blot analysis using antibodies against specific isoforms. Two Ca2+-dependent (-alpha, -gamma) and four Ca2+-independent (-delta, -epsilon, -zeta, and -lambda) isozymes were identified and two isozymes (-beta and -theta) were not detected in the subcellular fractions of PC12 cells. Treatment of the cells with TPA significantly activated translocation of conventional PKC-gamma from the cytosol to the membrane and nuclear fractions and other PKC isozymes (-alpha, -delta, and -epsilon) from the cytosol to the membrane, but not atypical PKC-zeta and -lambda. Although only the levels in the nuclear PKC-gamma but not other PKC isozymes were increased significantly following KCN, the levels of cPKC-alpha and -gamma in the membrane mainly- and those and PKC-epsilon in the nucleus-were increased when KCN was combined with TPA. In addition, this condition (TPA + KCN) did not affect the TPA insensitive atypical isozymes, PKC-zeta or -lambda. Taking the results together, differential activation/translocation of PKC isozymes by KCN and TPA is important in the regulation of chemical hypoxia-induced cell injury in PC12 cells.

Optimal proliferation of a hematopoietic progenitor cell line requires either costimulation with stem cell factor or increase of receptor expression that can be replaced by overexpression of Bcl-2

In vitro proliferation of hematopoietic stem cells requires costimulation by multiple regulatory factors whereas expansion of lineage-committed progenitor cells generated by stem cells usually requires only a single factor. The distinct requirement of factors for proliferation coincides with the differential temporal expression of the subunits of cytokine receptors during early stem cell differentiation. In this study, we explored the underlying mechanism of the requirement of costimulation in a hematopoietic progenitor cell line TF-1. We found that granulocyte-macrophage colony-stimulating factor (GM-CSF) optimally activated proliferation of TF-1 cells regardless of the presence or absence of stem cell factor (SCF). However, interleukin-5 (IL-5) alone sustained survival of TF-1 cells and required costimulation of SCF for optimal proliferation. The synergistic effect of SCF was partly due to its anti-apoptosis activity. Overexpression of the IL-5 receptor alpha subunit (IL5Ralpha) in TF-1 cells by genetic selection or retroviral infection also resumed optimal proliferation due to correction of the defect in apoptosis suppression. Exogenous expression of an oncogenic anti-apoptosis protein, Bcl-2, conferred on TF-1 cells an IL-5-dependent phenotype. In summary, our data suggested SCF costimulation is only necessary when the expression level of IL5Ralpha is low and apoptosis suppression is defective in the signal transduction of IL-5. Expression of Bcl-2 proteins released the growth restriction of the progenitor cells and may be implicated in leukemia formation.

Simultaneous high-performance liquid chromatographic analysis for famotidine, ranitidine HCl, cimetidine, and nizatidine in commercial products

A high-performance liquid chromatographic (HPLC) procedure for the simultaneous determination of famotidine (FMT), ranitidine HCl (RNT), cimetidine (CMT), and nizatidine (NZT) was developed using a two-level, full-factorial design with three variables (volume of methanol, percentage of triethylamine, and concentration of phosphate buffer) to select an acceptable mobile phase. A column (15 cm x 4.6 mm ID) of Inertsil ODS-2 (5 microns) was used, and 0.04 M aqueous sodium dihydrogen phosphate/acetonitrile/methanol/TEA at a proportion of 345/20/35/0.7 (v/v/v/v) was the selected mobile phase (1 ml/min). The detection wavelength was set at 230 nm, and procaine HCl was used as the internal standard. Precision and linearity of the method were assessed. None of the commercial samples was found to be outside the compendial limits of 90.0% to 110.0% of the claim amount.

Telescopic video microlaryngeal surgery

Although traditional microscopic laryngeal surgery has been well developed, we still may encounter some clinical problems, including exposure difficulty, blind areas during examination, and inadvertent cutting through lesions. These problems may lead to an increased risk of complications or protracted or even repeated operations. We have partially overcome these problems since October 1992 with a new telescopic endolaryngeal surgery technique. This technique was developed by combining and modifying the principles of bronchoscopic surgery and endoscopic sinus surgery. With this technique, it is not necessary to use a very slim laryngoscope or apply overpressure on the larynx when introducing and suspending the laryngoscope. Difficult-to-examine regions can be accessed more easily. We can also get a 3-dimensional impression of lesions and related structures, so it is easier to determine a proper cutting line to avoid cutting through lesions. We consider this telescopic method to be a useful alternative to conventional microscopic laryngeal surgery.

Magnolol protects cortical neuronal cells from chemical hypoxia in rats

The protective effect of magnolol, a component of Magnolia officinalis, against hypoxia-induced cell injury in cortical neuron-astrocyte mixed cultures was examined. Exposure of the cells to chemical hypoxia (0.5 mM KCN) produced morphological changes in neurons but not in astrocytes. KCN induced dose- and time-dependent increases in release of LDH and decreases in viable cell number. Treatment with magnolol (10 and 100 microM) significantly reduced the KCN-induced LDH release in a concentration-dependent manner. A higher concentration (750 microM) magnolol was toxic. Nuclear condensation was not observed in KCN-treated cells, suggesting that chemical hypoxia-induced cell death was via necrosis, rather than via apoptosis. This is the first report demonstrating that magnolol protects neurons against chemical hypoxic damage or necrotic cell death in cortical neuron-astrocyte mixed cultures.

Modified ultrafiltration in paediatric cardiopulmonary bypass

Cardiopulmonary bypass (CPB), a nonphysiological procedure, is associated with haemodilution and the inflammatory response, causing the accumulation of body water and organ dysfunction. The purpose of this study was to evaluate the efficacy of modified ultrafiltration. Forty paediatric patients undergoing cardiac operations were randomized into a control group and a modified ultrafiltration group. Blood cells, protein and cytokine concentrations were recorded for 24 h postoperatively. As the fluid was removed at 50 ml/min, both blood cells and protein were concentrated by modified ultrafiltration (p < 0.001). The tumour necrosis factor (TNF)-alpha concentration was increased and interleukin-8 (IL-8) and endothelin (ET) concentrations were unaltered after ultrafiltration. After correction for albumin, TNF-alpha concentration changed little, and IL-8 and ET concentrations (36.75 +/- 12.35, 42.89 +/- 15.54) were decreased significantly (21.47 +/- 13.87, 26.06 +/- 12.54) after ultrafiltration. Modified ultrafiltration is an effective method for removing excess tissue fluid and concentrating blood after CPB. This technique can also filter out some cytokines.

Amyloid beta peptide enhanced bradykinin-mediated inositol (1,4,5)trisphosphate formation and cytosolic free calcium

Deposition of amyloid beta protein (A beta) and alteration in signal transduction systems may have pathophysiological significance in Alzheimer's disease (AD). This study tested the hypothesis that bradykinin (BK) receptor-mediated signal transduction systems in PC12 cells are altered after treatment with A beta at a concentration not toxic to cells. Exposure to varying doses of A beta 25-35 (1-10 microM) for 18 hrs significantly reduced the number of viable cells, while lower concentrations (0.01-0.1 microM) and control peptide in scramble sequence had no effect. In addition, prolonged exposure of PC12 cells to a sublethal dose of A beta 25-35 (0.1 microM) affected the receptor-mediated signal transduction pathways. BK induced both accumulation of Ins(1,4,5)P3 and elevation in cytosolic free calcium concentration ([Ca2+]i) in the control cells. These responses were further enhanced in the cells treated with A beta. Under similar conditions, A beta-treated cells also demonstrated alterations in the number and affinity of BK receptors. Alternatively, extracellular addition of A beta elevated [Ca2+]i rapidly, without detectable alterations in Ins(1,4,5)P3. This rapid elevation was dependent on extracellular calcium, suggesting that A beta induced calcium influx. Taken together, the results demonstrated that treatment with a sublethal dose of A beta peptide for 18 hrs enhanced BK receptor mediated Ins(1,4,5)P3 formation and mobilization of intracellular calcium, associated with a modification in BK receptors. Changes in the balance of these receptor-mediated signals prior to cell injury could be an important underlying mechanism for A beta peptide-induced degenerative alteration in AD.

mcl-1 is an immediate-early gene activated by the granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling pathway and is one component of the GM-CSF viability response

mcl-1, a bcl-2 family member, was originally identified as an early gene induced during differentiation of ML-1 myeloid leukemia cells. In the present study, we demonstrate that Mcl-1 is tightly regulated by the granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling pathway. Upon deprivation of survival factor from TF-1 myeloid progenitor cells, Mcl-1 levels quickly dropped prior to visible detection of apoptosis of these cells. Upon restimulation of these deprived cells with GM-CSF, the mcl-1 mRNA was immediately induced and its protein product was accordingly resynthesized. Analysis with Ba/F3 cells expressing various truncation mutants of the GM-CSF receptor revealed that the membrane distal region between amino acids 573 and 755 of the receptor beta chain was required for mcl-1 induction. Transient-transfection assays with luciferase reporter genes driven by various regions of the mcl-1 promoter demonstrated that the upstream sequence between -197 and -69 is responsible for cytokine activation of the mcl-1 gene. Overexpression of mcl-1 delayed but did not completely prevent apoptosis of cells triggered by cytokine withdrawal. Its down regulation by antisense constructs overcame, at least partially, the survival activity of GM-CSF and induced the apoptosis of TF-1 cells. Taken together, these results suggest that mcl-1 is an immediate-early gene activated by the cytokine receptor signaling pathway and is one component of the GM-CSF viability response.

Leached components from dental composites in oral simulating fluids and the resultant composite strengths

The aim of this study was to analyse the leached moieties of dental composites after storage in ethanol and organic acids of plaque and further evaluate the resultant effect on the diametral tensile strength (DTS) of the composites. Three commercial composites were used: Bis-GMA-based Z100, Bis-GMA/UDMA-based Heliomolar, and Bis-MPEPP-based Marathon One. The solutions used were: 99.9% acetic acid, 99% propionic acid and 75% ethanol. Specimens (4 mm diam. x 2 mm thick) were stored at 37 degrees C in 3 mL of solution for up to 30 days. Gas chromatography/mass spectrometry was used to characterize the leached moieties and DTS of the specimens after immersion was evaluated. Data were analysed using ANOVA and Tukey LSD test. The eluted substances were not all the same in different solutions and composites but mostly increased with immersion time, and included diluents (TEGDMA and decamethacrylate) and some additives, such as an ultra-violet stabilizer (TINUVINP), plasticizers (dicyclohexyl phthalate and bis(2-ethylhexyl) phthalate), initiator (triphenyl stibine), coupling agent (gamma-methacryloxypropyl trimethoxysilane), and phenyl benzoate. The chief polymerizing monomers were not found. More kinds of components were found in the acetic acid and ethanol groups studied. The fewest kinds and quantities of leached moieties were found for Bis-GMA specimens and then Bis-GMA/UDMA ones, most of which are diluent agents. Bis-MPEPP specimens leached the most substances, which were composed mostly of a short phenyl group chain structure. The BisGMA composite showed the highest DTS (54.8 +/- 5.7 MPa), which was not greatly affected by the length of storage. Bis-GMA/UDMA (36.2 +/- 6.8 MPa) and Bis-MPEPP (26.1 +/- 4.5 MPa) composites were significantly reduced (P < 0.05) after 30 days storage in the ethanol (35-50%), in the propionic acid (25-30%), and in the acetic acid (40-60%). Irreversible processes such as the leaching of components occur in fluids simulating an oral environment, which may contribute to irreversible material degradation, especially for non-Bis-GMA-based composites.