bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduced Glycine Stimulation of [3H]MK‐801 Binding in Alzheimer's Disease
Authors: Procter A. W. , Wjong E. H. F. , Stratmann G. C , Lowe S. L. , Bowen D. M. 
Published: October 2006

AbstractThe novel N‐methyl‐D‐aspartate recjeptor channel ligand (+)‐[3H]5‐methyl‐J0, l1‐dihydro‐5H‐dibenzo[a, d]‐cyclohepten‐5, 10‐imine maleate ([3H]MK‐801) has been utilized to label this receptor in human brain tissiie. Characteristics of [3H]MK‐801 binding to well‐washeq membranes from 17 control subjects and 16 patients with Alzheimer's disease were determined in frontal, parietal, and temporal cerebral cortex and cerebellar cortex. In control tissue the pharmacological specificity of the binding of this substance is entirely consistent with the profile previously reported for rat brain. Binding could be stimulated by the addition of glutamic acid to the incubation medium; addition of glycine produced further enhancement which was not prevented by strychnine. The specificity of the effects of the and other amino acids on the binding was the same as in the rat. In Alzheimer's disease significantly less binding Was observed in the frontal cortex under glutamate‐ and glycine‐stimulated conditions. This appears to be associated with a reduced affinity of the site whereas the pharmacological specificity of the site remained unchanged. The effect did not appear to be due to differences in mode of death between Alzheimer's disease and control subjects and is unlikely to be related to factors for which the groups were matched. In contrast, binding was not altered in the absence of added amino acids and presence of glutamate alone. These results imply that in the cerebral cortex the agonist site and a site in the cation channel of the receptor are not selectively altered, but that their coupling to a strychnine‐insensitive glycine recognition site is impaired.
Polyclonal Antisera to the Individual Neurofilament Triplet Protdins: A Characterization Using ELISA and Immunoblotting
Authors: Karlsson J.‐E. , Rosengren L. E. , Haglid K. G. 
Published: October 2006

AbstractIn this article, the preparation and characterization of polyclonal rabbit antisera against the individual polypeptides of bovine neurofilament (68, 150, and 200 kilodaltons) is described. Selected antisera against the 68‐ add 150‐kilo‐dalton neurofilament polypeptides were specific for the corresponding antigen in homogenates of bovine, rat, and human brain as judged by immunoblots. The antisera against the 200‐kilodalton neurofilament polypeptide crossjreacted to some extent with the 150‐kilodalton neurofilament polypeptide, especially with the human antigen. The most specific antisera were used to develop an enzyme‐linked immunosorbent assay (ELISA), and the cross‐reactivities between the antisera and the different bovine and rat neurofilament polypeptides were determined. Contrary to the results In the immunoblots, the antiserum against the 200‐kilodalton neurofilament polypeptide was subunit‐specific, as was the 150‐kilodalton antiserum. The 68‐kilodalton antiserum displayed a minute cross‐reactivity against bovine 150‐ and 200‐kilodalton neurofilaments, but it cross‐reacted somewhat more with the rat 150‐ and 200‐kilodalton antigens. Even so, the subunit specificity of the antisera is high enough to enable the development of a quantitative ELISA for determination of the individual bovine or rat neurofilament polypeptides in a mixture. This study is the necessary preparation for such an assay.
Isolated Light Chain of Tetanus Toxin Inhibits Exocytosis: Studies in Digitonin‐Permeabilized Cells
Authors: Bittner Mary A. , Habig William H. , Holz Ronald W. 
Published: October 2006

AbstractPrevious work indicates that the heavy chain of tetanus toxin is responsible for the binding of the toxin to the neuronal membrane and its subsequent internalization. In the present study, the light chain of tetanus toxin mimicked the holotoxin in inhibiting Ca2+‐dependent secretion of [3H]norepinephrine from digitonin‐permeabilized adrenal chromaffin cells. Preincubation of tetanus toxin with monoclonal antibodies to the light chain prevented the inhibition by tetanus toxin. Preincubation of tetanus toxin with nonimmune ascites fluid or with monoclonal antibodies directed against the C fragment (the C‐terminal of the heavy chains or the heavy‐chain portion of the B fragment did not prevent inhibition by tetanus toxin. The data indicate that the light chain is responsible for the intracellular blockade of exostosis.
Discrete Distributions of Adenosine Receptors in Mammalian Retina
Authors: Blazynski Christine 
Published: October 2006

Abstract:Binding sites for both the adenosine A1 receptor agonists [3H]phenylisopropyladenosine and [3H]cyclohexyl‐adenosine and the mixed A1‐A2 agonist N‐[3H]ethylcarbox‐amidoadenosine ([3H]NECA) were localized in rabbit and mouse retinas using autoradiographic techniques. These two classes of agonists bound to very different regions of mammalian retinas. A1 agonist binding was localized to the inner retina, particularly over the inner plexiform layer. The binding of [3H]NECA was observed primarily over the retinal pigmented epithelium and the outer and inner segments of photoreceptors. [3H]NECA labeling was not affected either by including a low concentration of unlabeled A1 agonist or by pretreating tissue with N‐ethylmaleimide to inhibit ligand binding at A1 sites. While virtually all of the [3H]NECA binding was displaced by an excess of unlabeled NECA, displacement with antagonist or a large excess of cyclohexyladenosine revealed that ∼30% of the [3H]NECA binding was at non– A1, A2 sites. The majority of the binding in the outer retina thus labeled A2 receptor sites. The unique localizations of the two classes of adenosine receptors suggest different functions in visual processing.
Rapid Stereoselective Hydrolysis of (+)‐Cocaine in Baboon Plasma Prevents Its Uptake in the Brain: Implications for Behavioral Studies
Authors: Gatley S. J. , MacGregor R. R. , Fowler J. S. , Wolf A. P. , Dewey S. L. , Schlyer D. J. 
Published: October 2006

Abstract:The naturally occurring enantiomer of cocaine, (–)‐cocaine, has been previously labeled with 11C on the N‐methyl group and used in conjunction with positron emission tomography to show that cocaine is rapidly taken up in the striata of human and baboon brain. In the present study, the behaviorally inactive (+)‐cocaine was similarly labeled, with a view to its use for measuring the nonspecific binding of cocaine. No brain uptake was seen, although transport of cocaine into the brain is not expected to be stereoselective. The explanation for the lack of uptake was determined to be very rapid metabolism of (+)‐cocaine in the blood. By 30s after administration of labeled (+)‐cocaine, it was undetectable in plasma. In vitro studies demonstrated that (+)‐cocaine is 50% debenzoylated to (+)‐ecgonine methyl ester within 5 s of exposure to baboon plasma but not to washed erythrocytes. The hydrolysis of (–)‐cocaine is at least 1,000 times slower. Serum butyrylcholinesterase (EC 3.1.1.8) appears to be responsible for this hydrolysis, as evidenced by its inhibition by physostigmine and catalysis by commercially available pseudocholinesterase from horse and human blood.
Forskolin Mediates the Survival of Nerve Growth Factor‐Dependent Sympathetic Neurons of Chick Embryo by a Cyclic AMP‐Independent Mechanism
Authors: Wakade Arun R. , Bhave Sanjiv V. , Malhotra Ravindra K. , Wakade Taruna D. 
Published: October 2006

Abstract:Forskolin has become an invaluable tool for exploring the involvement of cyclic AMP in a variety of cellular functions. The diterpine directly activates the catalytic subunit of adenylate cyclase, causing a marked increase in cyclic AMP content. Because of this well‐characterized action, practically all the observed effects of forskolin are commonly attributed to cyclic AMP‐dependent processes. We show here that forskolin exerts a neurotrophic action that is almost identical to that of nerve growth factor (NGF) and phorbol 12,13–dibutyrate (PDB) but independent of cyclic AMP. Sympathetic neurons of the chick embryo supported in culture for 2 days by NGF, forskolin plus 3‐isobutyl‐l‐methylxanthine (IBMX), or PDB had almost identical levels of cyclic AMP (between 9 and 12 pmol/mg protein). Neurons supported in culture for 2 days by NGF or PDB when challenged with forskolin plus IBMX showed almost a 15‐fold increase in cyclic AMP, but those supported by forskolin plus IBMX and then exposed to the same combination of drugs did not show an increase in cyclic AMP, exhibiting a marked downregulation. Exposure of neurons to forskolin for 2 h was ineffective in supporting long‐term survival, suggesting that an initial increase in cyclic AMP formation is not sufficient but the continued presence of the drug is essential for survival. Effects of forskolin on the survival of these neurons could be observed even in the presence of dideoxyadenosine, an inhibitor of adenylate cyclase. Neurons supported by PDB for 2 days in culture when exposed to NGF for the first time did not show any increase in cyclic AMP, providing clear evidence that NGF does not affect this second messenger in its target cells. Similarly, neurons supported by NGF for 2 days when exposed to PDB did not show an increase in cyclic AMP. All these results rule out the involvement of cyclic AMP not only in the neurotrophic action of forskolin but also in that of NGF and PDB, and suggest that forskolin supports neuronal survival by some, as yet, unknown mechanism.
Effect of Peroxide, Sodium, and Calcium on Brain Mitochondrial Respiration In Vitro: Potential Role in Cerebral Ischemia and Reperfusion
Authors: Vlessis Angelo A. , Widener Linda L. , Bartos Dagmar 
Published: October 2006

Abstract:Mitochondrial pyruvate‐supported respiration was studied in vitro under conditions known to exist following ischemia, i.e., elevated extramitochondrial Ca2+, Na+, and peroxide. Ca2+ alone (7–10 nmol/mg) decreased state 3 and increased state 4 respiration to 81 and 141% of control values, respectively. Sodium (15 mM) and/or tert‐butyl hydroperoxide (tBOOH; up to 2,000 nmol/mg protein) alone had no effect on respiration; however, Na+ or tBOOH in combination with Ca2+ dramatically altered respiration. Respiratory inhibition induced by Ca2+ and tBOOH does not involve pyruvate dehydrogenase (PDH) inhibition since PDH flux increased linearly with tBOOH concentration (R= 0.96). Calcium potentiated tBOOH‐induced mitochondrial NAD(P)H oxidation and shifted the redox state of cytochrome b from 67 to 47% reduced. Calcium (5.5 nmol/mg) plus Na+ (15 mM) decreased state 3 and increased state 4 respiratory rates to 55 and 202% of control values, respectively. Sodium‐ as well as tBOOH‐induced state 3 inhibition required mitochondrial Ca2+ uptake because ruthenium red addition before Ca2+ addition negated the effect. The increase in state 4 respiration involved Ca2+ cycling since ruthenium red immediately returned state 4 rates back to control values. The mechanisms for the observed Ca2+‐, Na+‐, and tBOOH‐induced alterations in pyruvate‐supported respiration in vitro are discussed and a multifactorial etiology for mitochondrial respiratory dysfunction following cerebral ischemia in vivo is proposed.
The dynamic pattern of glucocorticoid receptor‐mediated transcriptional responses in neuronal PC12 cells
Authors: Morsink M. C. , Joëls M. , Sarabdjitsingh R. A. , Meijer O. C. , De Kloet E. R. , Datson N. A. 
Published: October 2006

AbstractThe aim of the current study was (i) to examine the overlap in the pattern of glucocorticoid receptor (GR)‐mediated transcriptional responses between different neuronal substrates and (ii) to assess the nature of these responses by differentiating between primary and downstream GR‐responsive genes. For this purpose, nerve growth factor‐differentiated catecholaminergic PC12 cells were used in which endogenous GRs were activated briefly with a high dose of corticosterone followed by gene expression profiling 1 and 3 h afterwards using Affymetrix GeneChips. The results revealed a strikingly similar temporal pattern to that which was reported previously in hippocampus, with only down‐regulated genes 1 h after GR activation and the majority of genes up‐regulated 3 h after GR activation. Real‐time quantatitive PCR of transcripts in cycloheximide‐treated cells showed that all five GR‐responsive genes selected from the 1‐h time point were primary responsive, whereas all four GR‐responsive genes selected from the 3‐h time point were downstream responsive. At the level of individual genes, the overlap with the previously generated hippocampal data sets was small, illustrating the cell‐type specifity of GR‐mediated genomic responses. Finally, we identified a number of interesting genes, such as SWI/SNF, synaptosomal‐associated protein 25 and certain Rab proteins which may play a role in the effects of glucocorticoids on catecholaminergic neuronal functioning.
Improved accuracy of intraocular lens power calculation with the Zeiss IOLMaster
Authors: Olsen Thomas 
Published: October 2006

Abstract.Purpose:  This study aimed to demonstrate how the level of accuracy in intraocular lens (IOL) power calculation can be improved with optical biometry using partial optical coherence interferometry (PCI) (Zeiss IOLMaster) and current anterior chamber depth (ACD) prediction algorithms.Methods:  Intraocular lens power in 461 consecutive cataract operations was calculated using both PCI and ultrasound and the accuracy of the results of each technique were compared. To illustrate the importance of ACD prediction per se, predictions were calculated using both a recently published 5‐variable method and the Haigis 2‐variable method and the results compared. All calculations were optimized in retrospect to account for systematic errors, including IOL constants and other off‐set errors.Results:  The average absolute IOL prediction error (observed minus expected refraction) was 0.65 dioptres with ultrasound and 0.43 D with PCI using the 5‐variable ACD prediction method (p < 0.00001). The number of predictions within ± 0.5 D, ± 1.0 D and ± 2.0 D of the expected outcome was 62.5%, 92.4% and 99.9% with PCI, compared with 45.5%, 77.3% and 98.4% with ultrasound, respectively (p < 0.00001). The 2‐variable ACD method resulted in an average error in PCI predictions of 0.46 D, which was significantly higher than the error in the 5‐variable method (p < 0.001).Conclusions:  The accuracy of IOL power calculation can be significantly improved using calibrated axial length readings obtained with PCI and modern IOL power calculation formulas incorporating the latest generation ACD prediction algorithms.
On the Specificity of Epidemic and Murine Typhus
Authors: Groupé Vincent , Donovick Richard 
Published: October 2006

The specificity of epidemic and murine typhus has been shown by active immunization of mice with killed rickettsial suspensions and subsequent challenge with heterologous and homologoustoxic substance.
During the preparation of this manuscript, Fitzpatrick published findings showing that 3 of 8 mice immunized with murine typhus vaccine were protected against 3 MLD of epidemic toxic substance administered intravenously and that 8 of 16 mice immunized with epidemic vaccine were protected against < 1 MLD of murine typhus rickettsiae administered intraperitoneally. These results suggested to Fitzpatrick that the toxic factor in the two strains is identical. Although there are antigens common to both strains, our findings do not support the suggestion that the two toxic substances are identical.
The Low Therapeutic Activity of Penicillin K Relative to That of Penicillins F, G, and X, and Its Pharmacological Basis
Authors: Eagle Harry , Musselman Arlyne 
Published: October 2006

One hour after the injection into rabbits or man of penicillins F, G, K, and X at 0.6 mg./kg., blood levels of K were one-fourth to one-eleventh of those observed with the other penicillins, and K persisted at demonstrable levels for relatively short periods.
In both rabbits and man the recovery of K in the urine averaged 30-35 per cent. This compares with an average recovery for F, G, and X of 74 per cent in rabbits and 91 per cent in man.
In the treatment of experimental pneumococcal infections in white mice, an impure preparation of K was one-sixth as active as G and one-eighth as active as X. In the treatment of experimental streptococcal infections in white mice, a pure preparation of K was one-eleventh as active as G, and one-thirtieth as active as X.

The above data suggest that penicillin K is inactivated in the body to a greater extent and more rapidly than either F, G, or X, resulting in a far lower therapeutic activity than would be anticipated from its bactericidal action
in vitro.
It seems clear that the amount of K in commercial penicillin should be minimized; and it would seem desirable to standardize impure mixtures of penicillins for therapeutic use by some method other than their bactericidal activity
in vitro.
Photosynthesis
Authors: Warburg Otto 
Published: October 2006

With the establishment of conditions for optimum culturing and measurement, there is now final proof that in photosynthesis at high as well as low light intensities the light energy can be almost completely converted into chemical energy. There is thus drawn to a close an investigation that was initiated many years ago in Berlin in the Imperial Institute of Physics (9).
The second result is the establishment of a general physical mechanism of photosynthesis, involving an interplay between light energy and respiratory energy, and therewith the solution of the quantum problem in photosynthesis.
The third result is the establishment of the function of chlorophyll as a stoichiometric, chemically reacting component in photosynthesis.

There remains the special chemistry of photosynthesis. In this still-unfinished field of investigation, the latest discovery is the labile carbon dioxide of
Chlorella
, connected with the decomposition and resynthesis of glutamic acid in living
Chlorella
, and connected with the possible function of the amino acids, aspartic and glutamic, in the binding and reduction of carbonic acid. The dissociating CO
2
is bound by
Chlorella
only in the presence of O
2
and of cellular glutamic acid. This CO
2
is released if the oxygen pressure is lowered below 2 mm of water or if—in the presence of oxygen—the glutamic acid is split in the living
Chlorella
, for example, by
N
/10,000 benzoquinone. This is the CO
2
that is used in light and taken up in the dark.
The Interpretive Cortex
Authors: Penfield Wilder 
Published: October 2006

The interpretive cortex has in it a mechanism for instant reactivation of the detailed record of the past. It has a mechanism also for the production of interpretive signals. Such signals could only be significant if past records are scanned and relevant experiences are selected for comparison with present experience. This is a subconscious process. But it may well be that this scanning of past experience and selection from it also renders the relevant past available for conscious consideration as well. Thus, the individual may refer to the record as he employs other circuits of the brain.
Access to the record of the past seems to be as readily available from the temporal cortex of one side as from that of the other. Auditory illusions (or interpretations of the distance, loudness, or tempo of sounds) have been produced by stimulation of the temporal cortex of either side. The same is true of illusional emotions, such as fear and disgust.
But, on the contrary, visual illusions (interpretations of the distance, dimension, erectness, and tempo of things seen) are only produced by stimulation of the temporal cortex on the nondominant (normally, right) side of the brain. Illusions of recognition, such as familiarity or strangeness, were also elicited only from the nondominant side, except in one case.
Ionospheric Topside Sounding
Authors: Calvert W. 
Published: October 2006

Over the past few years, the satellite topside sounders have significantly contributed to the understanding of the upper ionosphere. A great quantity of radio echo data has been accumulated, from which the ionospheric electron-density distribution can be determined.
The topside measurements of electron density essentially agree with similar measurements from the ground, except for an occasional 10-percent discrepancy near the peak of the ionosphere. While horizontal non-uniformity is a likely cause, this discrepancy has not yet been adequately explained.
The electron-density scale heights measured at a constant altitude indicate both a higher temperature and a heavier mean ion mass at high latitudes. At low latitudes the topside measurements have shown the detailed latitudinal structure of the equatorial anomaly, demonstrating control by the geomagnetic field.
A variety of electron-density irregularities have been studied. Most are greatly elongated along the magnetic field, and produce echoes either by lateral scattering, if they are thin, or by longitudinal ducting, if they are thick. Some of the thick irregularities are continuous between the hemispheres and support conjugate echo propagation.
The topside sounders have revealed the complex structure of the ionosphere near the auroral zone and at higher latitudes. At night an east-west trough of greatly reduced electron density occurs equatorward of the auroral zone. At the auroral zone itself the electron density is high and quite variable, both in space and time. The electron density at the polar cap within the auroral zone is often uniform and smooth. Ionospheric irregularities are common in the area of the trough and the auroral zone.
Among other satellites, the topside sounders have been used in various plasma studies involving the excitation and propagation of waves. These studies suggest that the ionosphere is an appropriate region for future plasma physics investigations, especially with rocket and satellite payloads designed specifically for that purpose.
The Ocean as a Chemical System
Authors: Sillén Lars Gunnar 
Published: October 2006

This discussion may have given the feeling that the present composition of ocean water does not result just from blind chance. The composition may in the main be given by well-defined equilibria, and the deviations from equilibrium may be explainable by well-defined processes. However, much remains to be discovered by laboratory work and studies of the natural systems.For any discussion of equilibria between sediments and sea water to become really fruitful and decisive, one must achieve a much better separation of the various sediment phases than has been obtained hitherto. Equilibrium data for various silicate systems are highly desirable. Studies of various elements indicate that there are serious gaps in our knowledge of soluble species and of equilibrium constants for known species; equilibrium measurements in the ionic medium, sea water, are scarce and not too reliable.Obviously, better understanding of the system ocean plus air plus sediments and of its history will require close cooperation between geologists, biologists, and chemists of various specialties.