bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autoradiographic localization of [3H]dextromethorphan in guinea pig brain: Allosteric enhancement by ropizine
Authors: Canoll P. D. , Smith P. R. , Gottesman S. , Musacchio J. M. 
Published: January 2005

AbstractDextromethorphan (DM) is an antitussive with anticonvulsant activity that binds to high‐ and low‐affinity sites in guinea pig brain homogenates. We examined the autoradiographic localization of [3H]DM using the anticonvulsant ropizine, an allosteric modifier that decreases the dissociation rate of [3H]DM. Competition studies demonstrated that the binding to brain sections was identical to that of brain homogenates [Craviso and Musacchio: Mol Pharmacol 23:629–640, 1983b]. Computer‐assisted quantitative analysis of the autoradiographic images demonstrated that [3H]DM binds to discrete structures throughout the brain, but with higher density in the midbrain, pons, and medulla oblongata. The most intense labeling was observed in the rhabdoid, dorsal raphe, median raphe, caudal linear raphe nuclei, and cranial motor nerve nuclei. The central gray showed moderate to high‐density labeling throughout its entire rostro‐caudal extent, with very high binding in the dorsal tegmental nucleus and the locus coeruleus. Moderate and high binding was also seen in several hypothalamic structures. Distinct bands of moderate binding were seen in the pyramidal cell layer of the piriform cortex, the retrosplenial cortex, the granular cell layer of the dentate gyrus, the pyramidal cell layer of the hippocampus, and the Purkinje cell layer of the cerebellum. The striking similarity between the binding distribution of [3H]DM and sigma ligands, plus competition studies in brain homogenate, support the hypothesis that DM and sigma ligands share a common highaffinity binding site [Musacchio et al: Mol Pharmacol 35:1–5, 1989]. The distribution of [3H]DM binding provides possible anatomical substrates for both the antitussive and anticonvulsant actions of DM.
Intravenous injection of [1‐14C]arachidonate to examine regional brain lipid metabolism in unanesthetized rats
Authors: DeGeorge J. J. , Noronha J. G. , Bell J. , Robinson P. , Rapoport S. I. 
Published: January 2005

AbstractWe examined the metabolic disposition and brain distribution of an unsaturated fatty acid, [1‐14C]arachidonate, between 5 and 240 min following its intravenous bolus injection in unanesthetized adult rats. Injected [1‐14C]arachidonate was cleared rapidly from plasma, with less than 10% remaining by 2 min. Total brain radioactivity, 0.2% of the injected dose, was near maximal by 5 min, reached a peak by 15 min, then slowly declined. Radioactivity in brain lipids constituted greater than 82% of the total brain radioactivity at all times. Radioactivity in aqueoussoluble metabolites was greatest at 5 min (13% of total) and declined to 5% by 240 min. Protein pelletassociated radioactivity gradually rose to a peak of 7% by 120 min. Within the lipid fraction, more than 92% of radioactivity was in glycerolipids, with greater than 81% in phospholipids. Radioactivity in inositol phosphoglyceride was maximal at 5 min (47% of phospholipid radioactivity); and declined to 34% by 20 min, whereas radioactivity in choline phosphoglyceride peaked at 15 min (41% of phospholipid radioactivity) and was constant thereafter. In contrast, radioactivity in ethanolamine phosphoglycerides increased from 7 to 17% during the course of the experiment. Quantitative autoradiography of brain sections indicated incorporation of [1‐14C]arachidonate into gray‐matter regions was 1.5‐ to threefold that into white‐matter regions. The data were analyzed in terms of a model for brain fatty acid uptake from plasma. Estimates of unidirectional transfer constants, k, for [1‐14]arachidonate from plasma to brain regions with an intact blood‐brain barrier ranged from 0.0005 to 0.0015 ml · sec−1 · g−1 and were correlated with those for [9,10‐3H]palmitate. The results indicate that brain phospholipid metabolism in awake animals can be examined regionally and quantitatively using intravenous injection of [1‐14C]arachidonate combined with quantitative autoradiography and biochemical analysis.
Multiple and novel specificities of monoclonal antibodies O1, O4, and R‐mAb used in the analysis of oligodendrocyte development
Authors: Bansal R. , Warrington A. E. , Gard A. L. , Ranscht B. , Pfeiffer S. E. 
Published: January 2005

AbstractThree monoclonal antibodies that react with antigens on the surface of developing oligodendrocytes in a stage‐specific manner, 01, 04 (Sommer and Schachner, 1981), and R‐mAb (Ranscht et al., 1982), have been studied with respect to their specificities for a number of purified lipids. The observed specificities were consistent regardless of how the antigens were presented to the antibodies. 01 reacted with galactocerebroside, monogalactosyl‐diglyceride, and psychosine and, in addition, labeled an unidentified species in rat brain extracts. R‐mAb reacted with galactocerebroside, monogalactosyl‐diglyceride, sulfatide, seminolipid, and psychosine; the reaction of R‐mAb with sulfatide was nearly equal to that with galactocerebroside. 04 reacted with sulfatide, seminolipid, and to some extent with cholesterol. However, oligodendrocyte progenitor cells labeling with 04 that had not yet begun to express the 01 antigen failed to incorporate 35SO4 or [3H]galactose into sulfatide or seminolipid, the syntheses of which first appear in 01‐positive cells. Therefore, 04 stains, in addition to sulfatide and seminolipid, an unidentified antigen that appears on the surface of oligodendrocyte progenitors prior to the expression of sulfatide and galactocerebroside. In primary cultures of rat brain, developing 04+ oligodendrocyte progenitors stained slightly earlier with R‐mAb than with 01, and thus R‐mAb transiently stained a larger population of oligodendrocytes than did 01. None of the three antibodies produced a detectable reaction on Western immunoblot after separation of brain proteins on reducing gels. In conclusion, the results show that 04, R‐mAb, and 01 have multiple overlapping specificities, including previously unrecognized cross‐reactions.
Expression of heat shock genes (hsp70) in the mammalian brain: Distinguishing constitutively expressed and hyperthermia‐inducible mRNA species
Authors: Brown I. R. , Rush S. J. 
Published: January 2005

AbstractThe mammalian genome contains both constitutively expressed and heat‐shock‐inducible members of the hsp70 gene family. Riboprobes derived from members of these two classes of heat shock genes were utilized in Northern blot studies to analyze brain mRNA isolated from control rabbits and rats and from animals subjected to hyperthermic treatment. Ariboprobe derived from a constitutively expresed hsp70 gene detected a 2.5 kilobase (kb) mRNA species in control rat brain. These brain mRNAs showed little change in abundance in animals which were subjected to hyperthermic treatment. A riboprobe derived from a heat‐shock‐inducible hsp70 gene detected an abundant 2.7 kb brain transcript in hyperthermic rabbits which was not apparent in control animals. A time course study revealed that the induction of this mRNA species was transient and paralleled the rise and fall in body temperature. Peak induction was observed at 1 hr. The level of this message had greatly decreased by 5 hr and only trace levels were present at 10 and 24 hr. In the rat brain the induced hsp70 mRNA species was slightly larger than that observed in rabbit (2.9 kb vs. 2.7 kb). The riboprobe which detected the hyperthermia‐inducible mRNA species was highly specific and did not cross react to the constitutively expressed mRNA species under the conditions employed in the Northern blot studies.
Neonatal hyperthyroidism in the rat produces an increase in the activity of microperoxisomal marker enzymes coincident with biochemical signs of accelerated myelination
Authors: Adamo A. M. , Aloise P. A. , Soto E. F. , Pasquini J. M. 
Published: January 2005

AbstractThe effect of neonatal hyperthyroidism produced by injection of tri‐iodothyronine (T3) on myelination and on the microperoxisomal population of the brain was studied in young rats. Data on the lipid composition of myelin show that myelinogenesis starts earlier in treated animals. In coincidence with the early appearance of myelin, there is an increase in the population of brain microperoxisomes, indicated by the increase in the activity of two enzymes that have been shown to be located in these organelles: catalase and acyl CoA‐dihydroxyacetone phosphate acyl transferase. Double‐label experiments using (1,2,3‐3H) and (2‐3H) glycerol to study the synthesis of glycerophospholipids throug the dihydroxyacetone phosphate (DHAP) pathway give further support to the above‐mentioned findings and suggest that there is an active participation of microperoxisomes in the synthesis of myelin lipids during the period of myelin formation.
Rat dopamine β‐hydroxylase: Molecular cloning and characterization of the cDNA and regulation of the mRNA by reserpine
Authors: McMahon A. , Geertman R. , Sabban Esther L. 
Published: January 2005

AbstractA number of cDNA clones for rat dopamine β‐hydroxylase (DBH) were isolated from a rat pheochromocytoma tumor cDNA library. The 2445 nucleotide sequence revealed a single open reading frame of 1860 nucleotides and a 3′ untranslated region containing two polyadenylation addition signals. The cDNA coded for a 620 amino acid protein of 69,883 daltons. Six potential glycosylation sites and one potential phosphorylation site were identified. Amino acid residues likely to be involved in the active site of DBH and in copper ligand binding were identified. The N‐terminal 42 amino acids appeared to constitute a typical but unusually long signal sequence. Hydropathy analysis indicated that this N‐terminal region contained the only extensive hydrophobic domain and thus constituted the only obvious potential membrane attachment site. Northern analysis detected two mRNA species of 2.5 and 2.7 kb. The relative abundance of the 2.7 vs. 2.5 kb mRNAs was differentially regulated in PC12 cells and adrenals upon treatment with reserpine.
Mapping of the Alz 50 epitope in microtubule‐associated proteins tau
Authors: Ksiezak‐Reding H. , Chien C.‐H. , Lee V. M.‐Y. , Yen Shu‐Hui 
Published: January 2005

AbstractAlz 50 and seven other monoclonal antibodies have been shown to react with both tau and Alzheimer brain proteins of molecular mass 60–70 kDa. The location of some of the epitopes of these antibodies (Alz 50, Tau‐2, NP14, Ab 636.7) on the tau molecule is unknown, whereas those of others (Tau 60, Tau 14, Tau‐1, Tau 46) have recently been demonstrated in fetal human tau at amino acid residues 60–72, 83–120, 131–140, and 315–352. To determine the location of the unknown epitopes, human tau was digested with chymotrypsin and trypsin, and the bovine microtubule fraction was incubated with chymotrypsin. Comparison of the immunoblots of chymotryptic digested tau with those of untreated preparations showed that the Alz 50 epitope was more sensitive than other tau epitopes to proteolysis. Cleavage of a 3–4 kDa polypeptide from the periphery of tau was sufficient to remove the Alz 50 epitope, but not the epitopes of Tau 46 (C‐end) or Tau 60 (N‐end). The distribution of the Alz 50 epitope in endogenously degraded, chymotrypsin or trypsin digested tau fragments was different from that of the Tau 46 epitope known to be located within 38 residues from the C‐terminus of the tau molecule. Based on these observations Alz 50 epitope was considered to be located within 3–4 kDa of the N‐terminus of tau. A comparison of immunoblots of different tau‐reactive antibodies showed similarities between Tau 60 and Tau‐2, and between Tau 14, Tau‐1, NP14, and Ab 636.7. Microtubule fractions, after chymotryptic digestion, retained small fragments (<29 kDa) reactive with all tau antibodies except Alz 50 and Tau 60. The two smallest fragments (<20–22 kDa), which were bound to digested microtubules and presumably contained microtubule binding domains, were recognized by Ab 636.7 and Tau 46. Among the eight tau‐reactive antibodies, the epitopes of Tau‐1, Ab 636.7, NP14, and Tau 46 were conserved in tau from human, bovine, rat, and mouse. The epitopes of the other four antibodies were more species specific. These results support our conclusion that the Alz 50 epitope is located at the N‐terminus of tau, the Tau‐2 epitope is located between Tau 60 and Tau 14 epitopes, and the Ab 636.7 and NP14 epitopes are in the C‐half of tau molecule closer than Tau‐1 epitope to the C‐terminus.
Fibroblast growth factor stimulates the proliferation and differentiation of neural precursor cells in vitro
Authors: Murphy M. , Drago J. , Bartlett P. F. 
Published: January 2005

AbstractWe have developed an in vitro culture system to study the regulation of proliferation and differentiation of neural precursor cells contained within the neuroepithelium of embruonic day 10 mice. Adnumber of soluble growth factoes have been tested for their ability to regulate these early events and, of these factors, we have found that the fibroblast growth factors [FGFs] can directly stimulate the proliferation and survival of the neuroepithelial cells. At least 50% of the neuroepithekuak cekks divide in the presence of FGF whereas in the absence of FGF all of the cells die within 6 days of cultural. At higher concentrations of FGF, the cells change from being nonadherent round cells in tight clusters into a more flattened cell type which adheres to the substratum. This morphological change is accompanied by the expression of both neurofilament and GFAP, which are definitive markersof the two major cell types in the central nervous system: neurons and glia. In addition a neuroepithelial cell line, which does not rely on FGF for survival or proliferation, expresses both of these markers in response to FGF. These results indicate that FGF is stimulating the differentation of the neuroepithelial cells into mature neurons and glia.
Multiple sclerosis and HLA class II susceptibility and resistance genes
Authors: Haegert D. G. , Michaud M. , Schwab C. , Francis G. S. 
Published: January 2005

AbstractProbes to the HLA class II genes DRβ, DQβ, and DQα were used to study DNA from unrelated Caucasian multiple sclerosis (MS) patients by sequential restriction fragment length polymorphism (RFLP) analysis in Taq1 restriction enzyme digests. Comparison of 104 patients and 108 controls, who were not matched for DR type, has identified for the first time a linked series of allele‐specific RFLPs or allogenotypes which form an extended haplotype that is preferentially associated with MS. These allogenotypes include DRw15 or DR2(15);DQβlb, which corresponds at the DNA level to the DQwl (DQw6) serotype; a DQA1 allogenotype termed DQα1b; and a 2.2kb DX (DQA2) allogenotype termed DXαU (DQA2U).The role of HLA class II genes in susceptibility to MS was found to be complex. First, 23 of 104 MS patients showed DR‐DQ linkages which were not observed in our control population. We suggest these anomalous associations may be important in the pathogenesis of MS. Second, homozygosity of a 2.0 KB DX (DQA2) gene, termed DXαL (DQA2L), Showed a strong negative association with MS. DXαL (DQA2L) is in strong linkage disequilobrium with DR1, 5(w11)7, and a subset of DR4, all of which also showed a negative association with MS, Since DXαL (DQA2L) does not code for any known product, DR1, 5(11), 4, and 7 become candidates for disease resistance genes. Third, in EcoR1 and EcoRV digests of DNA from both controls and patients homozygous for DQβ1b a number of different RFLP patterns were identified and these RFLPs patterns were identified and these RFLPs were associated with either relapsing‐remitting or progressive MS. This suggests there may be HLA sequence differences between individuals bearing a particular class II allele and these may correlate with the clinical course of MS.
Effect of chronic lead exposure on biopterin metabolism in the rat neostriatum
Authors: Martínez‐Fong Daniel , Gutiérrez M. E. , Aceves J. 
Published: January 2005

AbstractChronic (3 months) lead exposure increased the quinonoid dihydropteridine reductase activity and the tetrahydrobiopterin content but did not affect the GTP‐cyclohydrolase activity and the dihydrobiopterin content. These results suggest that lead intoxication may enhance dopamine metabolism in neostriatum by increasing the content of tetrahydrobiopterin, the regulating cofactor of tyrosine hydroxylase activity.
Expression of macrophage colony‐stimulating factor gene in the mouse brain during development
Authors: Théry C. , Hétier E. , Evrard C. , Mallat M. 
Published: January 2005

AbstractWe have investigated the expression of macrophagecolony stimulating factor (M‐CSF) gene in mouse brain during development. Northern blot analysis of cerebral RNA evidenced a 4.5‐kb M‐CSF transcript from day 14 of gestation until 2 weeks after birth. The cell type responsible for this transcription was studied using in vitro cell cultures. The 4.5‐kb M‐CSF transcript was found both in astrocyte primary cultures and in immortalized astrocytic cell lines. M‐CSF mRNA was also detected in lipopolysaccharide‐stimulated brain macrophage cultures. These results suggest that M‐CSF is involved in the outgrowth of microglia during ontogenesis.
Cultured microglial cells have a distinct pattern of membrane channels different from peritoneal macrophages
Authors: Kettenmann H. , Hoppe D. , Gottmann K. , Banati R. , Kreutzberg G. 
Published: January 2005

AbstractMicroglia are the source of the resident macrophages of the brain and thus belong to one of the most reactive cell types in cerebral tissue. They are attributed to have an important role in a number of pathological conditions, such as multiple sclerosis, viral infections like AIDS, and in lethal or sublethal injuries of neurons where the blood‐brain barrier is left intact (Streit et al., 1988; McGeer et al., 1988., Gendelman et al.,1989). Microglia share a number of macrophage characteristics but so far lack a distinguishing positive marker. In this study it is shown that microglia are distinguished from other macrophages by a unique pattern of ion channels.We compared membrane currents of microglial cells with those from peritoneal macrophages cultured under identical conditions. Although in macrophages a delayed outward K+ current was previously described (Randriamampita and Trautmann,1987), microglial cells lacked any specific outward current. Instead, these cells were characterized by large inwardly rectifying currents, activated by hyperpolarizing voltage steps. The reversal potential in different K+ gradients and the sensitivity of the current to Ba2+, TEA, and 4‐AP indicates that this current is K+ selective. In single‐channel recordings, a 30 pS K+ selective channel similar to the classical inward rectifier K+ channel was observed. Thus, the expression of membrane channels served not only to distinguish microglia from other cells inside and outside the brain, e.g., blood macrophages, but also suggests a unique functional state of this cell population.
Subtractive cDNA cloning of RC3, a rodent cortex‐enriched mRNA encoding a novel 78 residue protein
Authors: Watson J. B. , Battenberg E. F. , Wong K. K. , Bloom F. E. , Sutcliffe J. G. 
Published: January 2005

AbstractA rodent cortex‐enriched mRNA, RC3, was identified by screening a rat brain cDNA library with a cortex‐minus‐cerebellum subtracted cDNA probe. Conceptual translation of RC3 cDNA sequences indicates that the rat and mouse mRNA encode identical, novel 78 amino acid proteins. The RC3 protein amino terminus contains a cysteine‐rich domain similar to those found in snake venom neurotoxins; the carboxyl terminus contains a collagen‐like motif that may function in the assembly of RC3 subunits into a multimeric protein. Western blot experiments with an antiserum to a synthetic peptide corresponding to 27 residues of the 78 residue sequence identify an immunoreactive polypeptide with 18 kDa gel mobility that is likely to correspond to the RC3 protein. Northern blot analysis and in situ hybridization experiments show that RC3 mRNA is highly enriched in rat brain, with restricted expression in neuronal subsets primarily in the cortex, striatum, and hippocampus as well as certain nuclei within the thalamus, hypothalamus, the olfactory bulb.
Solubilization of A1 adenosine receptor from pig brain: Characterization and evidence of the role of the cell membrane on the coexistence of high‐ and low‐affinity states
Authors: Casadó V. , Cantí C. , Mallol J. , Canela E. I. , Lluis C. , Franco R. 
Published: January 2005

AbstractThe present solubilization strategy recognizes the important role of detergent cocktails in the solubilization and subsequent stability of adenosine A1, receptors from pig brain cortical membranes. The 3‐[3‐(cholamidopropyl) dimethylammonio]‐1‐propane‐sulfonate‐digitonin mixture produced the extraction of up to 52% of the receptor with an enrichment of 1.2‐fold with respect to crude membranes. The binding activity of the soluble extract was very stable even in the absence of glycerol. In crude membranes the existence of high‐ and low‐affinity states was detected, but in the soluble extract and in the detergent‐treated membranes only the high‐ affinity state was detected. Association‐dissociation curves showed that in crude membranes no interconversion between high‐ and low‐affinity sites is produced by the association of the ligand [3H]R‐N6 ‐phenylisopro‐pyladenosine. These results suggest that the high‐ and the low‐affinity states are different conformations induced by the structure of the membrane. The modulation of the binding activity by (Gpp(NH)p)5′ ‐guanylylimidodiphosphate and Mg2+ was studied. In crude membranes Gpp(NH)p shifted the high‐affinity state to the low‐affinity state, whereas the contrary occurred when Mg2+ was used. The effect of both Mg2+ and Gpp(NH)p was also assayed with the soluble extact and with the detergent‐treated membranes. In addition to a decrease of the overall binding capacity, Gpp(NH)p promoted a conversion to all low‐affinity states in the detergent‐treated membranes or to all very‐low‐affinity sites in the soluble extract. Mg2+ and Gpp(NH)p counteracted their effects in intact membranes, whereas Mg2+ could not reverse the uncoupling effect of Gpp(NH)p with solubilized or detergent‐treated membranes. Thus, it is suggested that Mg2+ acts at sites other than guanine‐nucleotide sites. If high‐affinity states correspond to receptor/G protein complexes and low‐affinity states correspond to the uncoupled receptor, we should conclude that Mg2+, as well as the loss of membrane integrity, favours the interaction of A1 receptor molecule with G protein.