bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of [3H]Triphenylmethylphosphomum Cation for Estimating Membrane Potential in Neuroblastoma Cells
Authors: Milligan Graeme , Strange Philip G. 
Published: October 2006

AbstractThe lipophilic permeant cation [3H]triphenylmethylphosphonium (TPMP) was used to estimate membrane potential in neuroblastoma N1E 115 cells under carefully controlled conditions. The cation distributes into the cells only in the presence of a lipophilic anion, and tetraphenylboron and picrate have been used for this purpose. The potassium salt of tetraphenylboron is poorly soluble, so that studies in high [K+] media are difficult with this anion whereas picrate, at the concentrations required, hyperpolarises the cells. The effect of muscarinic receptor activation was investigated by treating cells with carbachol but no effect was seen either on [3H]TPMP distribution or electrophysiological parameters. The use of [3H]TPMP for qualitative and quantitative evaluation of membrane potential in these cells is discussed.
Lesch‐Nyhan Syndrome, Caffeine Model: Increase of Purine and Pyrimidine Enzymes in Rat Brain
Authors: Miñana M. D. , Portolés M. , Jordá A. , Grisolía S. 
Published: October 2006

AbstractRats ingesting high doses of caffeine reproduce the self‐destructive behaviour observed in the Lesch Nyhan syndrome. This syndrome includes a deficit in hypoxanthine‐guanine phosphoribosyltransferase. We have observed, however, that the activity of hypoxanthine‐guanine phosphoribosyltransferase increases in direct proportion to the concentration of caffeine found in rat brain. It appears, therefore, that the caffeine model is not a true model for the Lesch‐Nyhan syndrome, or alternatively, that the deficit in hypoxanthine‐guanine phosphoribosyltransferase is coincidental and not a main key to the multifarious aspects of the syndrome, particularly the self‐mutilation. The possibility that levels of dopamine are increased in the caffeine model are discussed as a basis for the destructive behaviour. We have found also that ingestion of large amounts of caffeine increases the activities in rat brain of adenosine deaminase, purine nucleoside phosphorylase, aspartate carbamoyltransferase, dihydroorotase, and dihydroorotate oxidase.
Studies of Rat Brain Metabolism Using Proton Nuclear Magnetic Resonance: Spectral Assignments and Monitoring of Prolidase, Acetylcholinesterase, and Glutaminase
Authors: Middlehurst Carl R. , King Glenn F. , Beilharz Georg R. , Hunt Glenn E. , Johnson Gordon F. S. , Kuchel Philip W. 
Published: October 2006

AbstractThe first application of inversion‐recovery spin‐echo proton nuclear magnetic resonance spectroscopy to the monitoring of reactions in rat brain preparations is presented. The initial report of the assignment of proton spin‐echo nuclear magnetic resonance spectra from rabbit brain homogenates (C. R. Middlehurst et al., J. Neurochem. 42, 878–879, 1984) was used to assist in the assignment of spectra acquired from rat brain homogenates that were obtained from animals killed by cervical fracture or focussed microwave irradiation. Microwave‐irradiated brains were divided into four major anatomical regions. Differences in metabolite levels were detected when spectra from fresh tissue and from various regions were compared. The in situ steady‐state kinetics of prolidase in whole brain homogenate was determined.The procedure relies on the spectral differences between enzyme substrates and reaction products. The concentration dependence of the rate of hydrolysis of glycyl‐l‐proline was describable by the Michaelis‐Menten expression with a Michaelis constant of 1.90 mmol L‐1 and a maximal velocity of 9.30 μmol min‐1 mg‐1 protein. The reactions catalysed by glutaminase and acetylcholinesterase in the brain were also monitored.
Ionophore A23187, Verapamil, Protonophores, and Veratridine Influence the Release of γ‐Aminobutyric Acid from Synaptosomes by Modulation of the Plasma Membrane Potential Rather than the Cytosolic Calcium
Authors: Sihra Talvinder S. , Scott Ian G. , Nicholls David G. 
Published: October 2006

AbstractThe release of GABA induced by veratndine shows no correlation with the synaptosomal Ca content and is therefore not mediated by the release of mitochondrial Ca. Instead, with both Ca‐repleted and‐depleted synaptosomes, the extent of GABA efflux is correlated with the decrease in plasma membrane potential. The slow release of GABA induced by protonophores and the Ca‐dependent release induced by ionophore A23187 are also consequences of the depolarization of the plasma membrane, rather than of elevated cytosolic Ca. Finally, the ability of verapamil to inhibit the release of GABA induced by low veratridine concentrations is due to the ability of the Ca channel inhibitor to antagonize the action of veratridine, rather than to inhibit Ca entry into the synaptosome. It is concluded that it is essential to monitor plasma membrane potentials in experiments in which amino acid efflux from synaptosomes is induced.
Norepinephrine Stimulation of Phosphoinositide Hydrolysis in Rat Cerebral Cortex Is Associated with the Alpha1‐Adrenoceptor
Authors: Schoepp Darryle D. , Knepper Sheila M. , Rutledge Charles O. 
Published: October 2006

AbstractNorepinephrine (NE) and the selective alpha‐adrenoceptor agonist phenylephrine (PE) both markedly stimulate the formation of [3H]inositol phosphates in a concentration‐dependent manner upon incubation with [3H]myo‐inositol. The selective alpha2 agonist, clonidine, did not significantly alter [3H]inositol phosphate formation, even at concentrations as high as 10‐3M. The alpha, antagonist prazosin (IC50, 0.036 μM) was 300 times more potent than the alpha2 antagonist yohimbine (IC50, 10.7 μM) as an inhibitor of NE (10‐4M)‐stimulated phospha‐tidylinositol (PI) hydrolysis. These results indicate that the alpha1‐, but not the alpha2‐adrenoceptor subtype in rat brain is coupled to phosphoinositide hydrolysis.
Amphiphilic Detergent‐Soluble Acetylcholinesterase from Torpedo marmorata: Characterization and Conversion by Proteolysis to a Hydrophilic Form
Authors: Stieger S. , Brodbeck U. 
Published: October 2006

Abstract:The membrane‐bound acetylcholinesterase (AChE) from the electric organ of Torpedo marmorata was solubilized by Triton X‐100 or by treatment with proteinase K and purified to apparent homogeneity by affinity chromatography. Although the two forms differed only slightly in their subunit molecular weight (66,000 and 65,000 daltons, respectively), considerable differences existed between native and digested detergent‐soluble AChE. The native enzyme sedimented at 6.5 S in the presence of Triton X‐100 and formed aggregates in the absence of detergent. The digested enzyme sedimented at 7.5 S in the absence and in the presence of detergent. In contrast to the detergent‐solubilized AChE, the proteolytically derived form neither bound detergent nor required amphiphilic molecules for the expression of catalytic activity. This led to the conclusion that limited digestion of detergent‐soluble AChE results in the removal of a small hydrophobic peptide which in vivo is responsible for anchoring the protein to the lipid bilayer.
Synapsin I Is Associated with Cholinergic Nerve Terminals in the Electric Organs of Torpedo, Electrophorus, and Malapterurus and Copurifies with Torpedo Synaptic Vesicles
Authors: Volknandt W. , Naito S. , Ueda T. , Zimmermann H. 
Published: October 2006

AbstractUsing an affinity‐purified monospecific polyclonal antibody against bovine brain synapsin I, the distribution of antigenically related proteins was investigated in the electric organs of the three strongly electric fish Torpedo marmorata, Electrophorus electricus, Malapterurus electricus and in the rat diaphragm. On application of indirect fluorescein isothiocyanate‐immunofluorescence and using α‐bungarotoxin for identification of synaptic sites, intense and very selective staining of nerve terminals was found in all of these tissues. Immunotransfer blots of tissue homogenates revealed specific bands whose molecular weights are similar to those of synapsin Ia and synapsin Ib. Moreover, synapsin I‐like proteins are still attached to the synaptic vesicles that were isolated in isotonic glycine solution from Torpedo electric organ by density gradient centrifugation and chromatography on Sephacryl‐1000. Our results suggest that synapsin I‐like proteins are also associated with cholinergic synaptic vesicles of electric organs and that the electric organ may be an ideal source for studying further the functional and molecular properties of synapsin I.
Morphological and Neurochemical Effects of Diazepam and Phenobarbital on Selective Culture of Neurons from Fetal Rat Brain
Authors: Daval Jean‐Luc , De Vasconcelos Anne Pereira , Lartaud Isabelle 
Published: October 2006

AbstractThe responses to diazepam (DZ) and phenobarbital (PhB) were studied in enriched neuronal primary cultures from rat embryo hemispheres. Cells were grown in chemically defined medium and the drugs were added for 3 days to cultures, at pharmacologically active concentrations. Following exposure to DZ or to PhB, morphological changes, such as less prominent neuronal processes, were observed in neurons. It was also shown that each drug reduced the specific uptake of 2‐deoxy‐D‐glucose by the cells and interfered with protein and RNA metabolism. It was concluded that both DZ and PhB might affect, at least transiently, the normal growth of neurons in culture.
Differentiation‐Dependent Sialylation of Individual Neural Cell Adhesion Molecule Polypeptides During Postnatal Development
Authors: Breen Kieran C. , Regan Ciaran M. 
Published: October 2006

AbstractThe postnatal sialylation of individual neural cell adhesion molecule (N‐CAM) polypeptides by a develop‐mentally regulated sialyltransferase in Golgi‐enriched fractions isolated from rat brain is described. The 120‐kilodal‐ton polypeptide of N‐CAM was found to be sialylated at each developmental age examined. This was in contrast to the 140‐ and 180‐kilodalton N‐CAM polypeptides which were only sialylated until postnatal day 10 and from postnatal day 12, respectively. Immunoblotting procedures demonstrated that all N‐CAM polypeptides were expressed in the Golgi fractions at each developmental stage examined. The heavily sialylated “embryonic” form of N‐CAM was found to be reexpressed at postnatal days 10 and 12, a time coincident with extensive fibre outgrowth. The “embryonic” form of N‐CAM incorporated similar amounts of [14C]sialic acid into its constituent polypeptides reflecting the difference in sialic acid to protein ratio, as this form of N‐CAM was virtually undetectable in the immunoblots of postnatal material.
Regulation of Muscarinic Agonist‐Induced Activation of Phosphoinositidase C in Electrically Permeabilized SH‐SY5Y Human Neuroblastoma Cells by Guanine Nucleotides
Authors: Wojcikiewicz Richard J. H. , Lambert David G. , Nahorski Stefan R. 
Published: October 2006

Abstract: myo‐[3H]Inositol‐labelled SH‐SY5Y cells were permeabilized with electrical discharges. 3H‐Inositol phosphate formation in cells shown to be fully permeable was stimulated by the muscarinic agonist carbachol, by guanosine 5′‐(γ‐thio)triphosphate [GTP(S)], and by guanosine 5′‐(β‐thio)diphosphate (GppNHp). Synergism was observed on coincubation of these GTP analogues with carbachol. GTP was also stimulatory and guanosine 5′‐(β‐thio)diphosphate was inhibitory in the presence of agonist. Atropine blocked the effects of carbachol. Stimulation by GTP(S) (0.1 mM) occurred after a 1‐2‐min lag, whereas Ca2+ (0.5 mM), carbachol (1 mM), and carbachol plus GTP(S) stimulated without delay. The effects of carbachol plus GTP(S) but not those of Ca2+ were inhibited by spermine (4 mM). Accumulation of 3H‐inositol phosphates was enhanced by Li+ (4 mM) only in intact cells. In intact or permeabilized cells, the “partial” agonist arecoline was maximally 40–50% as efficacious as carbachol. In permeabilized cells, the maximal effects of carbachol and arecoline were enhanced 2.8‐ and 5.3‐fold, respectively, by 0.1 mM GTP(S), but only the EC50 for carbachol was substantially reduced. The binding affinity of carbachol but not that of arecoline in permeabilized cells was significantly reduced by 0.1 mM GppNHp. These data indicate that a guanine nucleotide‐binding regulatory protein is involved in coupling muscarinic receptors to phosphoinositidase C in SH‐SY5Y cells and that the activity of this protein influences the relationship between receptor occupation and phosphoinositide response.
Boosting effect of bisphosphonates on osteoconductive materials: a histologic in vivo evaluation
Authors: Houshmand B. , Rahimi H. , Ghanavati F. , Alisadr A. , Eslami B. 
Published: October 2006

Background and Objective:  The effect on bone regeneration, of adding pamidronate disodium to bovine‐derived hydroxyapatite, was histologically evaluated, using the sheep bone model.Material and Methods:  Twenty‐four intrabony defects were prepared in the lower jaw of eight sheep using trephine 6 mm burs. One cavity was left unfilled and the other two were filled with bovine‐derived hydroxyapatite (BioOss™) alone (control group) or with bovine‐derived hydroxyapatite mixed with pamidronate disodium (Aredia) (case group), respectively. After 6 wk, the animals were killed and the coded samples observed using an optical microscope. The percentage of regenerated bone, number of osteoclasts and amount of inflammation was recorded. Statistical analysis was carried out using chi‐square and Mann–Whitney U‐tests.Results:  The results manifested a significant difference in the amount of bone formation, with the most being observed in the case group and the least in the negative‐control group (p < 0.001). Significantly fewer osteoclasts were observed in the case group than in the other groups (p < 0.001). The amount of inflammation did not seem to differ within the case and control groups (p > 0.05).Conclusion:  Adding pamidronate disodium to bovine‐derived hydroxyapatite improves its osteoconductive and regenerative specifications. Further study should determine the systemic effects of a single local administration of these drugs, and their appropriate dose and type, with minimal risk.
The Site of Action of DDT in the Cockroach
Authors: Roeder Kenneth D. , Weiant Elizabeth A. 
Published: October 2006

(1) Although DDT undoubtedly affects motor nerves and muscle fibers in concentrations greater than 1,000 ppm, this action cannot be directly responsible for the clonic tremors in the DDT-poisoned cockroach which can be produced by internal concentrations of the order of 5 ppm.
(2) DDT has no significant action on the cockroach central nervous system.
(3) DDT emulsion perfused through the leg of the cockroach in concentrations as low as 0.01 ppm causes the appearance of a series of high frequency trains of axon spikes in the afferent fibers.
(4) It is concluded that the tremors characteristic of DDT poisoning are due to an intense afferent bombardment of the motor neurons.
Patterns and Populations
Authors: Ehrlich Paul R. , Holm Richard W. 
Published: October 2006

In summary, then, we would like to suggest that in broad investigations of the patterns of interaction and relationship among organisms the artificial and stultifying fragmentation of population biology into divisions such as taxonomy, population genetics, and ecology should be ignored. Care also should be taken to scrutinize current concepts such as "species," "niche," and "community." If some emergent patterns seem to correspond to a great degree with these concepts, then the concepts may be given operational definitions and the labels should be retained. If there is no such correspondence, then the concepts will have outlived their usefulness and should be discarded.
The basic units of population biology are not communities, species, or even populations, but individual organisms. In populations, variation, growth, genetic equilibria, selection, behavior, and so on are not "things" but relationships. Therefore, what is of interest in population biology is the pattern in which organisms are related in space and time.
Biomedical Science in Europe
Authors: Grant R. P. , Huttrer C. P. , Metzner C. G. 
Published: October 2006

European biomedical research is now in full resurgence, 19 years after the devastation of the World War II. The more advanced countries of Western Europe are gradually approaching a position of economic self-sufficiency with respect to research. However, certain problems persist. Lingering nationalism and language differences continue to inhibit Europe from finding its full strength as a scientific community. Educational reforms, manpower planning, and scientific support still lag far behind the technologic recovery of science. International pooling of scientific interests and activities, so necessary for the smaller countries, has been slow to develop.
The bonds between American and European biomedical science are extraordinarily strong and healthy, the result of the huge flow of young Europeans to America and of American scientists to Europe for training. These training exchanges have done much more than extend technologic competence. The two communities, one European, the other American, have different attitudes and atmospheres for research, which complement and strengthen each other. The benefits which lie in collaborative research and training among laboratories of the two communities are becoming more and more apparent and no doubt will lead to new levels of creativity and productivity in biomedical research.
Birth Control after 1984
Authors: Djerassi Carl 
Published: October 2006

1) Eric Blair (alias George Orwell) can rest easy in his grave, because birth control by governmentally imposed methods, such as incorporation of a contraceptive agent into drinking water, is totally unfeasible by 1984.
2) Fundamentally new birth control procedures in the female (for example, a once-a-month luteolytic or abortifacient agent) and a male contraceptive pill probably will not be developed until the 1980's at the earliest, and then only if major steps of the type outlined in this article are instituted in the early 1970's. Development during the next decade of practical new methods of birth control without important incentives for continued active participation by the pharmaceutical industry is highly unlikely. If none are developed, birth control in 1984 will not differ significantly from that of today.
Soil Deterioration and the Growing World Demand for Food
Authors: Brink R. A. , Densmore J. W. , Hill G. A. 
Published: October 2006

A recent survey of five watersheds in south-central Wisconsin, where corn is now the dominant annual crop, illustrates the soil erosion damage that is occurring on sloping land under modern agricultural technology and prevailing market forces. In 70 percent of the 93 quarter-sections sampled, estimated soil losses, on the average, were more than twice the amounts considered compatible with permanent agriculture. Scattered studies by others indicate that the findings are meaningful for a large area in the United States when row cropping is prevalent on sloping soils.
Pressures on cultivated land, in general, are mounting rapidly because of the rising demand for meat in industrialized nations and the soaring numbers of marginally fed people in Third World countries. The world population-food problem makes increasing stress on U.S. soils inevitable in the foreseeable future. Adequate protection against excessive loss of productive topsoil requires that the level of publicly supported soil conservation activities be promptly adjusted to this circumstance.
The BiSearch web server
Authors: Arányi Tamás , Váradi András , Simon István , Tusnády Gábor E 
Published: October 2006

Abstract

Background
A large number of PCR primer-design softwares are available online. However, only very few of them can be used for the design of primers to amplify bisulfite-treated DNA templates, necessary to determine genomic DNA methylation profiles. Indeed, the number of studies on bisulfite-treated templates exponentially increases as determining DNA methylation becomes more important in the diagnosis of cancers. Bisulfite-treated DNA is difficult to amplify since undesired PCR products are often amplified due to the increased sequence redundancy after the chemical conversion. In order to increase the efficiency of PCR primer-design, we have developed BiSearch web server, an online primer-design tool for both bisulfite-treated and native DNA templates.

Results
The web tool is composed of a primer-design and an electronic PCR (ePCR) algorithm. The completely reformulated ePCR module detects potential mispriming sites as well as undesired PCR products on both cDNA and native or bisulfite-treated genomic DNA libraries. Due to the new algorithm of the current version, the ePCR module became approximately hundred times faster than the previous one and gave the best performance when compared to other web based tools. This high-speed ePCR analysis made possible the development of the new option of high-throughput primer screening. BiSearch web server can be used for academic researchers at the http://bisearch.enzim.hu site.

Conclusion
BiSearch web server is a useful tool for primer-design for any DNA template and especially for bisulfite-treated genomes. The ePCR tool for fast detection of mispriming sites and alternative PCR products in cDNA libraries and native or bisulfite-treated genomes are the unique features of the new version of BiSearch software.
Overexpression of Eag1 potassium channels in clinical tumours
Authors: Hemmerlein Bernhard , Weseloh Rüdiger M , Mello de Queiroz Fernanda , Knötgen Hendrik , Sánchez Araceli , Rubio María E , Martin Sabine , Schliephacke Tessa , Jenke Marc , Heinz-Joachim-Radzun  , Stühmer Walter , Pardo Luis A 
Published: October 2006

Abstract

Background
Certain types of potassium channels (known as Eag1, KCNH1, Kv10.1) are associated with the production of tumours in patients and in animals. We have now studied the expression pattern of the Eag1 channel in a large range of normal and tumour tissues from different collections utilising molecular biological and immunohistochemical techniques.

Results
The use of reverse transcription real-time PCR and specifically generated monoclonal anti-Eag1 antibodies showed that expression of the channel is normally limited to specific areas of the brain and to restricted cell populations throughout the body. Tumour samples, however, showed a significant overexpression of the channel with high frequency (up to 80% depending on the tissue source) regardless of the detection method (staining with either one of the antibodies, or detection of Eag1 RNA).

Conclusion
Inhibition of Eag1 expression in tumour cell lines reduced cell proliferation. Eag1 may therefore represent a promising target for the tailored treatment of human tumours. Furthermore, as normal cells expressing Eag1 are either protected by the blood-brain barrier or represent the terminal stage of normal differentiation, Eag1 based therapies could produce only minor side effects.