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.

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.

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.

Following the recovery of naso-pharyngeal cancer patients by trace elements in hair using statistical pattern recognition methods

This article describes a study where the recovery of nasopharyngeal cancer (NPC) patients was traced by trace elements (TEs) in hair of these patients. These patients whose concentrations of TEs in hair were studied are volunteers who were divided into three groups B, C, and D. Group B was made up of volunteers who had just been diagnosed as having NPC, group C and group D were made up of volunteers who had been diagnosed as having NPC after 3 and 6 mo, respectively, of treatment. For comparison, a control group, namely group A, which was made up of volunteers from healthy persons was added to this study. By implementation of statistic pattern recognition methods, it has been found that the concentrations of TEs in hair can remarkably reflect different recovery phases of NPC patients.

Differential effects of heavy metals on the binding of Xenopus upstream binding factor(xUBF) to DNA

Xenopus upstream binding factor (xUBF) is a transcription factor for RNA polymerase I which contains multiple DNA-binding motifs. Among these DNA-binding motifs, HMG box I is essential for promoting RNA polymerase I-dependent rRNA gene transcription. Gel shift assay indicated that the binding of recombinant HMG box I to a 136-bp linear DNA probe was significantly inhibited by Cd2+ at 1 microM. The formation of larger protein-DNA complexes was particularly sensitive to Cd2+. The interaction between HMG box I and DNA was completely inhibited by 10 microM of Cd2+, yet this interaction was not inhibited by the same concentration of Ca2+. Hg2+ at 0.1 microM began to cause abnormal band shifting, and protein-DNA bands disappeared to the wells of a polyacrylamide gel in the presence of 10 microM of Hg2+, reflecting that a drastic change in the conformation of HMG box I-DNA had occurred. The binding of HMG box I to DNA was slightly disturbed by As3+ at 1 microM and was significantly affected at 10 microM. Our results suggest that inhibition of the normal binding of UBF to its target DNA may be one of the mechanisms of heavy metal-induced inhibition of RNA synthesis.

The design and application of a pediatric centrifugal pump

This centrifugal pump (CP) includes two parts: the blood pump and the driving apparatus. They are connected by six twin magnetic disc plates and driven by a magnetic DC motor (120W). The blood pump had six leaves deadlocked between two plastic discs. Six leaves were set at 30 degrees angles, separately. In the lower chamber of the CP, there was an inlay magnetic disc, which is connected with the disc leaves by an axis. This axis was sealed by silicon rubber and a ceramic ring. The priming volume of the blood chamber was 34 ml. In vitro testing showed that the free hemoglobin caused by the CP was much less than that caused by a roller pump after 180 min. The effect of this CP on blood cell damage was also studied in an animal model. Six goats were placed on cardiopulmonary bypass for 180 min. Perfusion flow rates were maintained between 1.5 and 2.5 L/min. The plasma free hemoglobin was lower in the CP group (6.04 mg/dL) than in the roller pump group (32.25 mg/dL), p < 0.01. The CP has been used in ten pediatric patients undergoing cardiopulmonary bypass surgery. The patients' ages were from three to five years, and body weights were from 15 to 20 kg. Perfusion flow rates were maintained between 1.8 and 2.5 L/min, and bypass times were from 30 to 50 min. The rotation speeds were from 2000 to 2500 rpm. All the patients recovered smoothly, and no hemoglobinuria occurred.

Analysis of trace elements in the hair of volunteers suffering from naso-pharyngeal cancer

This article describes a study where the trace elements (TEs) of four groups of volunteers were analyzed. The volunteers were divided into four groups A, B, C, and D. Group A was made up of healthy subjects, group B was made up of volunteers who had just been diagnosed as having naso-pharyngeal cancer (NPC), group C was made up of volunteers who had been diagnosed as having NPC after 3 mo of treatment, and group D was made up of volunteers who had been diagnosed as having NPC after 6 mo of treatment. In all groups, 11 trace elements in hair were analyzed. Our study shows that the concentrations of zinc (Zn), copper (Cu), manganese (Mn), and cobalt (Co) in group B are less than that of group A, whereas the concentration of titanium (Ti) in group B is higher. Our results also show that the difference in the level of TEs between group A and the other groups is dramatically decreased as the time of the treatment is increased. This may be a reflection of successful treatment.

Altered phospholipid metabolism in sodium butyrate-induced differentiation of C6 glioma cells

We examined the changes in phospholipid metabolisms in sodium butyrate-treated C6 glioma cells. Treatment of 2.5 mM sodium butyrate for 24 h induced an increase in the activity of glutamine synthetase, suggesting that these cells were under differentiation. Similar treatment was associated with (i) increased arachidonic acid incorporation into phosphatidylcholine, and (ii) decreased arachidonic acid incorporation into phosphatidylinositol and (iii) phosphatidylethanolamine. These effects were subsequently investigated by examining the acylation process, de novo biosynthesis, and the agonist-stimulated phosphoinositides hydrolysis in these cells. Our results indicated that sodium butyrate stimulated the acylation of arachidonic acid into lysophosphatidylcholine, lysophosphatidylethanolamine, and lysophosphatidylinositol. The glycerol incorporation into these lipids was not affected, but the inositol incorporation into total chloroform extracts and Pl and phosphatidylinositol 4-phosphate was decreased in the sodium butyrate-treated cells. Moreover, the accumulation of the rapid histamine-stimulated phosphoinositide metabolites, i.e., inositol monophosphate, inositol diphosphate, and inositol triphosphate (IP3) was decreased in these cells. To elucidate whether the decreased inositol phosphates were due to a decrease in the phosphoinositides hydrolysis, we measured the transient IP3 production directly by a receptor-binding assay. Our results indicated that histamine-stimulated transient IP3 formations were decreased. Taken together, these results indicated that multiple changes by multiple mechanisms of phospholipid metabolisms were found in sodium butyrate-treated C6 glioma cells. The decreased IP3 formation and its subsequent action, i.e., Ca2+ mobilization, may play an early but pivotal role by which sodium butyrate induces C6 glioma cell differentiation.

Regulation of bradykinin-induced Ins(1,4,5)P3 formation by protein kinase C in human fibroblasts

To better understand the molecular mechanisms that underlie the exaggerated bradykinin (BK)-stimulated release of Ins(1,4,5)P3 in fibroblasts from Alzheimer patients, the role of G-proteins, protein kinase C (PKC) and cyclic AMP in BK-induced Ins(1,4,5)P3 formation was determined. A role for G-proteins in the coupling of the BK receptor to intracellular signals was indicated by guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) enhanced BK-stimulated Ins(1,4,5)P3 release. The coupling of G-proteins to Ins(1,4,5)P3 formation was sensitive to cholera toxin (CTX), but not pertussis toxin (PTX), and was not altered by PKC activation. The inhibition by CTX appeared to be secondary to its ability to increase cyclic AMP, because forskolin also inhibited the BK-mediated Ins (1,4,5)P3 release. Activation of PKC with TPA diminished the number of BK receptors by 33% and proportionally decreased BK-mediated Ins(1,4,5)P3 formation by 28%. The latter response was abolished by PKC inhibitors. Depletion of PKC by prolonged TPA treatment did not further alter the number of BK receptors but further decreased the Ins(1,4,5)P3 response by 65%. Thus, changes in PKC probably do not underlie the enhanced BK-induced Ins(1,4,5)P3 formation in AD fibroblasts, because both activation and depletion of the PKC diminished the Ins(1,4,5)P3 response.

Apoptosis of gamma/delta T cells in human ehrlichiosis

Expansion of activated T cells expressing the T-cell receptor (TCR) gamma/delta, CD45RO, and HLA-DR antigens is a prominent feature of acute infection with Ehrlichia chaffeensis in humans. The fate of these activated cells and the resolution of the gamma/delta T-cell response with return to the usual alpha/beta T-cell populations in this disease are not clearly understood. At a morphologic level, apoptotic cells are present in the peripheral blood during the acute and resolution phases of the infection. Simple culture of density gradient-separated lymphocytes from the blood of patients with acute ehrlichiosis produced cell death rapidly in the media compared to alpha/beta T cells. This loss of viability after incubation was apparently mediated by apoptosis, based on flow cytometric and morphologic analyses. The results suggest that most primed (CD45RO+) and activated (HLA-DR+) gamma/delta T cells in acute ehrlichiosis might be subject to removal from the body by programmed or apoptotic cell death.

The role of signal transduction systems in mediating cell density dependent changes in tyrosine hydroxylase gene expression

Cell density has been implicated in the regulation of neuronal gene phenotype. This study tested the interaction of signal transduction pathways and the expression of tyrosine hydroxylase (TH) mRNA with varying cell density. Increasing cell density in a parental, wild type PC12 cell line elevated steady state levels of TH mRNA. Three observations suggested that this induction is not related to the cyclic AMP dependent signalling pathway: (1) Forskolin stimulated the level of TH mRNA similarly at multiple densities. (2) PKA deficient mutant PC12 cell lines that have either one third (A123.7, AB11) or 3% (A126-1B2) of normal basal expression of TH mRNA still exhibit the same density induced elevation of TH mRNA levels as the wild type. (3) Different cell densities did not change cyclic AMP concentrations in the basal or in the receptor stimulated state. Increasing cell density did not change basal levels of inositol triphosphate (IP3) levels, which suggests that the phosphatidylinositol cascade (PI) is not responsible for density dependent changes in TH expression. Increasing confluence was highly correlated to [Ca2+]i in control (r = 0.70; P < 0.0001), A123.7 (r = 0.92; P < 0.001), AB11 (r = 0.72; P < 0.0001) and A126 (r = 0.42; P < 0.07). Taken together, the results show that neither cyclic AMP nor the PI cascade is involved in cell density induced changes in TH mRNA and suggest that altered [Ca2+]i may have a role.

Increased inositol 1,4,5-trisphosphate accumulation correlates with an up-regulation of bradykinin receptors in Alzheimer's disease

An alteration in signal transduction systems in Alzheimer's disease (AD) would likely be of pathophysiological significance, because these processes control normal brain functions. Previously, a diminished beta-adrenergic-mediated cyclic AMP response was found in cultured fibroblasts from AD patients. Because cross-talk between the phosphoinositide and cyclic AMP pathways exists, the phosphoinositide cascade was studied under conditions that were similar to those for studying the cyclic AMP response. Cells from AD patients and age-matched controls responded to bradykinin (BK) and released inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in a time- and dose-dependent manner. The level of Ins(1,4,5)P3 increased rapidly and transiently in response to BK, peaked at 5 s, but still remained 116-132% above the basal level by 30 s. Although the temporal patterns were similar in both groups, the Ins(1,4,5)P3 concentrations in AD fibroblasts were 73 and 89% above levels in the age-matched controls at 5 and 10 s, respectively. Prostaglandin E1 also increased Ins(1,4,5)P3 formation, but this response was not different between the two groups. Although KD (affinity) values for the BK receptor were similar in both control and AD cells, the number of BK receptors (Bmax) was significantly elevated in AD fibroblasts (186.8 +/- 0.8 fmol/mg of protein) as compared with control fibroblasts (57.2 +/- 15.3 fmol/mg of protein). These results indicate that the elevated Ins(1,4,5)P3 production in response to BK in AD fibroblasts is positively correlated with an increase in the receptor numbers.

Finite element analysis of cerebral contusion

Finite element analysis was carried out to study the mechanism of cerebral contusion. Clinical findings indicate that most cerebral contusions in the absence of skull fracture occur at the frontal and temporal lobes. To explain these observations, cavitation and shear strain theories have long been advocated. Plane strain finite element models of a parasagittal section of the human head were developed in the present study. The model was first validated against a set of experimental results from the literature. Frontal and occipital impacts were then simulated, and pressure and shear stress distributions in the brain were compared. While comparable negative pressures always developed in the contrecoup regions, shear stress distributions remained nearly identical regardless of the impact direction, consistent with the clinically observed pattern for contusion. Therefore, shear strain theory appears to account better for the clinical findings in cerebral contusion.

The role of cytosolic free calcium in the regulation of pyruvate dehydrogenase in synaptosomes

Calcium homeostasis and mitochondrial oxidative metabolism interact closely in brain and both processes are impaired during hypoxia. Since the regulation of the pyruvate dehydrogenase complex (PDHC) may link these two processes, the relation of cytosolic free calcium ([Ca2+]i) to the activation state of PDHC (PDHa) was assessed in isolated nerve terminals (i.e. synaptosomes) under conditions that alter [Ca2+]i. K+ depolarization elevated [Ca2+]i and PDHa and both responses required external calcium. Treatment with KCN, an in vitro model of hypoxia decreased ATP and elevated [Ca2+]i and PDHa. Furthermore, in the presence of KCN, PDHa became more sensitive to K+ depolarization as indicated by larger changes in PDHa than in [Ca2+]i. The calcium ionophore Br-A23187 elevated [Ca2+]i, but did not affect PDHa. K+ depolarization elevated [Ca2+]i and PDHa even if [Ca2+]i was elevated by prior addition of ionophore or KCN. Previous in vivo studies by others show that PDHa is altered during and after ischemia. The current in vitro results suggest that hypoxia, only one component of ischemia, is sufficient to increase PDHa. These data also further support the notion that PDHa is regulated by [Ca2+]i as well as by other factors such as ATP. Our results are consistent with the concept that PDHa in nerve endings may be affected by [Ca2+]i and that these two processes are clearly linked.

Altered beta-adrenergic receptor-stimulated cAMP formation in cultured skin fibroblasts from Alzheimer donors

An alteration in signal transduction systems in Alzheimer's disease would likely be of pathophysiological significance, because these steps are critical to normal brain function. Since dynamic processes are difficult to study in autopsied brain, the current studies utilized cultured skin fibroblasts. The beta-adrenergic-stimulated increase in cAMP was reduced approximately 80% in fibroblasts from Alzheimer's disease compared with age-matched controls. The deficit in Alzheimer fibroblasts in response to various adrenergic agonists paralleled their beta-adrenergic potency, and enhancement of cAMP accumulation by a non-adrenergic agonist, such as prostaglandin E1, was similar in Alzheimer and control fibroblasts. Diminished adenylate cyclase activity did not underlie these abnormalities, since direct stimulation of adenylate cyclase by forskolin elevated cAMP production equally in Alzheimer and control fibroblasts. Cholera toxin equally stimulated cAMP formation in Alzheimer and control fibroblasts. Moreover, cholera toxin partially reduced isoproterenol-induced cAMP deficit in Alzheimer fibroblasts. Pertussis toxin, on the other hand, did not alter the Alzheimer deficits. The results suggest either that the coupling of the GTP-binding protein(s) to the beta-adrenergic receptor is abnormal or that the sensitivity of receptor is altered with Alzheimer's disease. Further, any hypothesis about Alzheimer's disease must explain why a reduced beta-adrenergic-stimulated cAMP formation persists in tissue culture.

Characterization of seven newly established nasopharyngeal carcinoma cell lines

BACKGROUND

Nasopharyngeal carcinoma (NPC) has a relatively high incidence in Chinese living in Taiwan, Hong Kong, Singapore, and South China. To better understand this cancer, we have established several new NPC cell lines.

EXPERIMENTAL DESIGN

We collected biopsy specimens from suspected NPC patients and divided each specimen into two parts: the first part was fixed for routine histopathologic examination, and the other part was put into culture medium for primary culture. Once the cell lines were established, they were extensively characterized.

RESULTS

Seven NPC cell lines were established, and all have been passaged more than 100 times. Two lines were derived from keratinizing carcinomas and five from undifferentiated carcinomas. Electron microscopic examination revealed that both dark and light tumor cells contained intermediate filaments with clear desmosome formation. The average doubling time ranged from 10.7 to 16.3 hours. Karyotypic analysis showed multiple chromosome abnormalities with the average chromosome number between 84 and 95. Colony forming efficiency in soft agar was 18-42%. All cell lines could induce solid tumor mass formation when transplanted into nude mice, and the histopathological findings showed two keratinizing and five nonkeratinizing carcinomas. All cell lines contained less acidic keratin polypeptides than basic keratin polypeptides. Strong expression of vimentin in each single cell of all cell lines was also observed. The oncosuppressor retinoblastoma gene in each cell line showed no remarkable abnormality, but retinoblastoma protein was abnormally expressed in some interphase cells. The oncogenes, erbB and c-fgr, were both normally expressed. While the c-myc oncogene in all cell lines was overexpressed when compared with the Burkitt's lymphoma Raji Cell line, the c-myc DNA sequence in each cell line showed neither amplification nor rearrangement.

CONCLUSIONS

The newly established seven NPC cell lines have been well characterized, and all showed overexpression of c-myc oncogene. The oncosuppressor retinoblastoma gene revealed no remarkable rearrangement, but its protein product was abnormal in certain interphase cells of each cell line.

Selenium in Kashin-Beck disease areas

In this article, the duplication portion technique was used to determine the daily intakes of selenium and ten other elements in the 24-h total diets collected in the typical Kashin-Beck endemic areas, i.e., Shanxi Province and Inner Mongolia Autonomous of China. The contents of Ca, Mg, Cu, Fe, Zn, Mn, Al, Sr, Ba, and P in freeze-dried samples were determined by ICP-AES. Se was determined by differential pulse catalytic polarography. The average Se contents in total diets of Shanxi Kashin-Beck endemic and nonendemic areas were 0.009 and 0.021 micrograms/g (dry weight), respectively (P less than 0.001), corresponding to the daily intakes for Se of 4.6 and 10.5 micrograms. After the Se-supplemented fertilizer was applied (225 g of Na2SeO3/ha), the average Se content in total diets of Kashin-Beck disease area was increased to 0.0336 micrograms/g, which corresponded to the average daily intake for Se of 16.8 micrograms. In Inner Mongolia Kashin-Beck endemic and nonendemic areas, the average Se contents in total diets were 0.006 and 0.017 micrograms/g, respectively (p less than 0.001), corresponding to the average daily intakes for Se of 3 and 8.5 micrograms. The contents of other ten elements in total diets in endemic and nonendemic areas were reported and compared.

Inositol phosphates and intracellular calcium after bradykinin stimulation in fibroblasts from young, normal aged and Alzheimer donors

Several studies suggest that alterations in the receptor-mediated phosphoinositide cascade and cytosolic free calcium concentration ([Ca2+]i) are involved in the pathophysiology of aging and Alzheimer's disease. Therefore, the phosphoinositide cascade and [Ca2+]i were determined under resting conditions and after stimulation with bradykinin (100 nM) in cultured human skin fibroblasts from young (21 +/- 3 years), normal aged (59 +/- 6 years) and Alzheimer subjects (58 +/- 6 years). The inositol polyphosphates (IP3, IP2 and IP) were monitored after prelabeling the cells with [3H]inositol in serum free medium. [Ca2+]i was determined with the fluorescent probe, fura-2AM, under exactly analogous conditions. The bradykinin-induced formation of IP3 and IP2 increased significantly in fibroblasts from normal aged and Alzheimer donors compared to young subjects, but did not differ from each other. Bradykinin-induced IP3 formation was 63-117% above the young group at time points between 10-60 s in normal aged or Alzheimer donors. Bradykinin-induced IP2 formation was 49-59% above the young group at time points between 10-60 s in normal aged or Alzheimer subjects. Neither the basal [Ca2+]i, nor the bradykinin-stimulated [Ca2+]i, differed among fibroblasts from young, normal aged and Alzheimer donors. The precise molecular basis and pathophysiological significance of the enhanced bradykinin-induced phosphoinositide cascade in fibroblasts from aged donors remains to be determined.

Cross-resistance to UV radiation of a cisplatin-resistant human cell line: overexpression of cellular factors that recognize UV-modified DNA

A human cell line selected for cisplatin resistance (CPR) was irradiated with UV light and showed cross-resistance to UV light. Applying a modified chloramphenicol acetyltransferase assay, we observed that CPR cells acquired enhanced host cell reactivation of a transfected plasmid carrying UV damage. Gel mobility shift analysis indicated that two nuclear factors that recognize UV-modified DNA were overexpressed in CPR cells. In addition, factors that bind UV-modified DNA were independent from the factors that bind cisplatin-modified DNA. The significance of the identified binding factors, possibly DNA repair enzymes, is discussed.

Cytosolic free calcium concentrations in synaptosomes during histotoxic hypoxia

Altered cytosolic free calcium concentrations ([Ca2+]i) accompany impaired brain metabolism and may mediate subsequent effects on brain function and cell death. The current experiments examined whether hypoxia-induced elevations in [Ca2+]i are from external or internal sources. In the absence of external calcium, neither KCl depolarization, histotoxic hypoxia (KCN), nor the combination changed [Ca2+]i. However, with external CaCl2 concentrations as small as 13 microM, KCl depolarization increased [Ca2+]i instantaneously while hypoxia gradually raised [Ca2+]i. The combination of KCN and KCl was additive. Increasing external calcium concentrations up to 2.6 mM exaggerated the effects of K+ and KCN on [Ca2+]i, but raising medium calcium to 5.2 mM did not further augment the rise. Diminishing the sodium in the media, which alters the activity and perhaps the direction of the Na/Ca exchanger, reduced the increase in [Ca2+]i due to hypoxia, but enhanced the KCl response. The changes in ATP following K+ depolarization, KCN or their combination in the presence of physiological calcium concentrations did not parallel alterations in [Ca2+]i, which suggests that diminished activity of the calcium dependent ATPase does not underlie the elevation in [Ca2+]i. Valinomycin, an ionophore which reduces the mitochondrial membrane potential, elevated [Ca2+]i and the effects were additive with K+ depolarization in a calcium dependent manner that paralleled the effects of hypoxia. Together these results suggest that hypoxia-induced elevations of synaptosomal [Ca2+]i are due to an inability of the synaptosome to buffer entering calcium.

Sodium arsenite induces ATP depletion and mitochondrial damage in HeLa cells

Our present results show that treatment with sodium arsenite apparently decreases cellular ATP levels in a dose- and time-dependent manner in HeLa S-3 cells. The reduction in ATP induced by sodium arsenite was possibly through mitochondrial damage, since treatment with sodium arsenite resulted in reduction of rhodamine 123 accumulation and disruption of the structure of the cristae in mitochondria. However, all of these changes could be reversed by removing sodium arsenite from the culture medium. The levels of ATP depletion were correlated with the killing effects of sodium arsenite in HeLa S-3 cells.

Interactions between inositol phosphates and cytosolic free calcium following bradykinin stimulation in cultured human skin fibroblasts

The inositol triphosphate (IP3) that results from hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) is generally accepted to be responsible for the mobilization of intracellular calcium. However, some studies suggest that low concentrations of agonists elevate cytosolic free calcium concentration ([Ca2+]i) without IP3 formation. Thus, in the present studies, a comparison of the temporal response of inositol phosphates (IP3, IP2 and IP) and [Ca2+]i to a wide range of bradykinin concentrations was used to examine the relation of these two signal transduction events in cultured human skin fibroblasts (GM3652). In addition, the effects of alterations in internal or external calcium on the response of these second messengers to bradykinin were determined. Bradykinin stimulated accumulation of inositol phosphates and a rise of [Ca2+]i in a time- and dose-dependent manner. Decreasing the bradykinin concentration from 1 microM to 0.1 microM increased the time until the IP3 peak, and when the bradykinin concentration was reduced to 0.01 microM IP3 was not detected. [Ca2+]i was examined under parallel conditions. As the bradykinin concentration was reduced from 1 microM to 0.01 microM, the time to reach the peak of [Ca2+]i increased progressively, but the magnitude of the peak was unaltered. These two second messengers were variably dependent on external calcium. Although the bradykinin-stimulated initial spike of [Ca2+]i did not depend on extracellular calcium, the subsequent sustained levels of [Ca2+]i were abolished in calcium free medium. The bradykinin-stimulated inositol phosphate formation was not dependent on the extracellular calcium nor on the elevation of [Ca2+]i that was produced with Br-A23187. These results demonstrate that bradykinin-induced IP3 formation can be independent of [Ca2+]i and of external calcium, whereas changes in [Ca2+]i are partially dependent on external calcium.

Cytosolic free calcium and ATP in synaptosomes after ischemia

Elevations in cytosolic free calcium ([Ca2+]i) precede electrophysiological alterations due to ischemia in vivo. An in vitro model of these changes would help to elucidate their molecular basis. A model of postdecapitative ischemia was used to study these interactions. Nerve endings (i.e. synaptosomes) were isolated either immediately after decapitation or at various time periods after decapitation. Synaptosomal [Ca2+]i and ATP concentrations were determined during a basal period and following depolarization. K(+)-depolarization produced an initial spike of [Ca2+]i that was followed by a new equilibrium value. Ischemia elevated the basal [Ca2+]i and the new equilibrium [Ca2+]i after KCl but suppressed the [Ca2+]i spike. However, the difference between the basal [Ca2+]i and the new equilibrium [Ca2+]i after K(+)-depolarization did not vary with ischemia. Although ischemia reduced ATP, K(+)-depolarization did not alter ATP concentrations in either the controls or the ischemia group, which suggests that synaptosomal mitochondria can meet an energy demand after ischemia. ATP was inversely related to the basal or the new equilibrium [Ca2+]i following depolarization. These changes in [Ca2+]i may underlie the alterations in neurotransmitter release and cell death following ischemia. This appears to be a useful model in which to study the molecular basis of ischemia induced changes in [Ca2+]i.

The cellular basis of delirium and its relevance to age-related disorders including Alzheimer's disease

A wide variety of conditions lead to delirium (i.e., metabolic encephalopathies) in human beings and animals. Despite the varied etiology the clinical consequences are relatively stereotyped which suggests that the diverse insults that cause delirium may act by common metabolic and cellular "final pathways." Related molecular and cellular mechanisms may be involved in aging and Alzheimer's disease, conditions that predispose to the development of delirium. Animal models of delirium better reflect age-related disorders such as Alzheimer's disease than those that impair a single neurotransmitter system such as the cholinergic system; the metabolic encephalopathies produce global cognitive disturbance, which is more typical of these disorders. Thus, research related to delirium has far-reaching implications for normal and abnormal brain function.

Simple enzymatic determination of total cholesterol in gallstones

In this simple method for rapid enzymatic determination of total cholesterol in human gallstones, gallstone powder is dissolved in an 80/20 by vol mixture of N,N-dimethylformamide and dimethyl sulfoxide and reacted directly with the aqueous enzymatic reagent, without further treatment. The organic solvents do not interfere with enzymatic activities of cholesterol oxidase, esterase, and peroxidase in the assay mixture. The method is reproducible (CVs 3.7% to 6.6%), analytical recoveries ranged from 98.6% to 102%, and linearity is good. Furthermore, results correlated well with those obtained by infrared spectroscopic measurements.

Simple enzymatic determination of total cholesterol in gallstones

In this simple method for rapid enzymatic determination of total cholesterol in human gallstones, gallstone powder is dissolved in an 80/20 by vol mixture of N,N-dimethylformamide and dimethyl sulfoxide and reacted directly with the aqueous enzymatic reagent, without further treatment. The organic solvents do not interfere with enzymatic activities of cholesterol oxidase, esterase, and peroxidase in the assay mixture. The method is reproducible (CVs 3.7% to 6.6%), analytical recoveries ranged from 98.6% to 102%, and linearity is good. Furthermore, results correlated well with those obtained by infrared spectroscopic measurements.

Phosphatidylinositol metabolism during in vitro hypoxia

The effects of in vitro histotoxic hypoxia (0.5 mM KCN) on potassium-stimulated phosphatidylinositol turnover were determined. In rat cortical slices that were prelabeled with [2-3H]inositol, depolarization with 60 mM KCl increased [2-3H]inositol monophosphate and [2-3H]inositol bisphosphate accumulation in a Ca2+-dependent manner. At early times (10 s and 1 min), histotoxic hypoxia enhanced potassium-stimulated [2-3H]inositol monophosphate and inositol bisphosphate accumulation. Under basal conditions, hypoxia did not alter the accumulation of [2-3H]inositol phosphates. These results are consistent with the following hypothesis. The hypoxic-induced increase in cytosolic free calcium that we reported previously may lead to the early stimulation of inositol phosphates formation during hypoxia through activation of phospholipase C. The impairment of inositol phosphates formation during more prolonged hypoxia may be due to negative feedback regulation of the phosphatidylinositol cascade by protein kinase C or to a reduction in ATP levels.

The effect of vitamin B2 and its derivatives on a dry-reagent strip theophylline assay

This report describes the effect of flavin adenine dinucleotide (FAD) and its precursor vitamin B2 on an apoenzyme reactivation immunoassay system (ARIS) both in vitro and in vivo. It was observed that 10 nM/L FAD in the buffer causes a false-positive result in ARIS for theophylline by the value of 94 microM/L, whereas vitamin B2, flavin mononucleotide, adenosine, adenosine monophosphate, and adenosine diphosphate (ADP) at the same concentration caused no such effect. Nevertheless, ADP at 2 microM/L can cause a drop in theophylline reading of 55 microM/L. However, the sera from four volunteers with normal liver functions who had taken 30 mg of vitamin B2 daily for a week showed no effect on theophylline reading.

Effects of in vitro hypoxia on depolarization-stimulated accumulation of inositol phosphates in synaptosomes

The effects of potassium and in vitro histotoxic hypoxia (i.e. KCN) on phosphatidylinositol turnover in rat cortical synaptosomes were determined. [2-3H] Inositol prelabelled rat synaptosomes were prepared from cerebral cortex slices that had been incubated with [2-3H] inositol. Depolarization with 60 mM KCl increased [2-3H] inositol phosphates in a time dependent manner. Depolarization with 60 mM KCl increased [2-3H] inositol trisphosphate transiently at 5 s. K+ induced rapid formation of [2-3H]-inositol bisphosphate and maintained an elevated level for at least 5 min. K+ stimulated gradual formation of [2-3H] inositol monophosphate with time. One minute of hypoxia enhanced potassium-stimulated [2-3H] inositol bisphosphate formation. However, 30 min of hypoxia impaired potassium-stimulated accumulation of [2-3H] inositol phosphates. The effects of histotoxic hypoxia were all dependent upon calcium in the medium and on K+-depolarization. Thus, hypoxia altered the K+-induced accumulation of inositol phosphates in prelabelled synaptosomes in a time dependent, biphasic manner that was calcium dependent.

Oxidative damage in DNA. Lack of mutagenicity by thymine glycol lesions

Thymine glycol (5,6-dihydroxy-5,6-dihydrothymine) is a base damage common to oxidative mutagens and the major stable radiolysis product of thymine in DNA. We assessed the mutagenic potential of thymine glycols in single-stranded bacteriophage DNA during transfection of Escherichia coli wild-type and umuC strains. cis-Thymine glycols were induced in DNA by reaction with the chemical oxidant, osmium tetroxide (OsO4); modification of thymines was quantitated by using anti-thymine glycol antibody. Inactivation of transfecting molecules showed that one lethal hit corresponded to 1.5 to 2.1 thymine glycols per phage DNA in normal cells, whereas conditions of W-reactivation (SOS induction) reversed 60 to 80% of inactivating events. Forward mutations in the lacI and lacZ' (alpha) genes of f1 and M13 hybrid phage DNAs were induced in OsO4-treated DNA in a dose-dependent manner, in both wild-type and umuC cells. Sequence analysis of hybrid phage mutants revealed that mutations occurred preferentially at cytosine sites rather than thymine sites, indicating that thymine glycols were not the principal pre-mutagenic lesions in the single-stranded DNA. A mutagenic specificity for C----T transitions was confirmed by OsO4-induced reversion of mutant lac phage. Pathways for mutagenesis at derivatives of oxidized cytosine are discussed.