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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although voltage-sensitive sodium channels play a central role in electrogenesis in neurons, rat brain sodium channels are also present in some glial cells. To determine whether rat brain sodium channel alpha-subunit isotypes are expressed in other cell types, we examined osteoblasts within the embryonic day 17 (E17) vertebral column with in situ hybridization and immunocytochemical methods. For in situ hybridization studies, riboprobes hybridizing to isoform-specific sequences in the 3'-noncoding region of sodium channel mRNAs (NCI, NCII and NCIII) were utilized. Sodium channel mRNA I and III were not detectable in osteoblasts of the vertebra centrum or neural arches in E17 rats. In contrast, sodium channel mRNA II was moderately expressed by osteoblasts in the developing vertebral column of E17 rats. In immunocytochemical experiments, antipeptide antibodies directed against conserved and isotype-specific regions of the sodium channel alpha-subunit were used. Antibody SP20, which recognizes a conserved region of the sodium channel, intensely stains osteoblasts in both the vertebra centrum and neural arches. Antibody SP11-I, which recognizes sodium channel I, exhibited negligible-to-low levels of immunostaining in vertebral column osteoblasts. Osteoblasts reacted with antibody SP11-II, which recognizes sodium channel II, displayed moderate levels of immunostaining. Antibody SP32-III, which recognizes sodium channel III, displayed negligible levels of staining in osteoblasts within vertebra centrum and neural arches. These results demonstrate that osteoblasts in situ within E17 vertebral columns express sodium channel II mRNA and protein. Together with previous electrophysiological observations, the present results suggest that functional sodium channels are expressed in osteoblasts in vivo. These results extend the range of non-neuronal cells known to express rat brain sodium channels.
Brain Res Mol Brain Res 1995 Dec 01
PMID:Type II brain sodium channel expression in non-neuronal cells: embryonic rat osteoblasts. 875 Aug 64

Cryptococcus neoformans is an encapsulated fungus that causes a life-threatening meningoencephalitis in patients with AIDS. Monoclonal antibodies to the capsular glucuronoxylomannan can modulate the infection in mice, but the epitopes on this complex polysaccharide recognized by protective and non-protective antibodies have not been defined. We have used 2H1, one of our most protective antibodies, to screen phage display peptide libraries for peptide mimotopes that would allow us to explore the fine specificity of anti-cryptococcal polysaccharide antibodies. Hexa- and decapeptides have been identified with sequence homologies that define four motifs: 1, (E)TPXWM/LM/L; 2, W/YXWM/ LYE; 3, DWXDW; and 4, (Ar)WDGQ(Ar). Peptides representing these motifs compete with each other for a shared binding site that overlaps the polysaccharide binding site. Motifs 1 and 2 confer high affinity binding, and PA1, which displays a motif 1 peptide with the sequence LQYTPSWMLV, binds to 2H1 with a Kd of 295 nM. Analysis of the interaction between the 2H1 binding peptides and 24 structurally related anti-polysaccharide antibodies reveals a complex pattern of reactivity that strongly suggests binding to or close to the complementary determining regions. Furthermore, those antibodies that have been shown to have different specificity, and in some cases different protective potential, do not bind any of the peptides selected by the protective 2H1 antibody. This study shows that peptide mimotopes for a complex microbial polysaccharide can be identified by screening phage peptide libraries and demonstrates the usefulness of such peptides in analyzing closely related interactive sites of proteins in general and of antibodies in particular.
J Mol Biol 1996 Aug 09
PMID:Peptide libraries define the fine specificity of anti-polysaccharide antibodies to Cryptococcus neoformans. 876 Apr 99

The expression of sodium channel alpha-, beta 1- and beta 2-subunit mRNAs was examined in adult rat DRG neurons in dissociated culture at 1 day in vitro and within sections of intact ganglia by in situ hybridization and reverse transcription polymerase chain reaction (RT-PCR). The results demonstrate that sodium channel alpha-subunit mRNAs are differentially expressed in small (< 25 microns diam), medium (25-45 microns diam.) and large (> 45 microns diam.) cultured DRG neurons at 1 day in vitro (div). Sodium channel mRNA I is expressed at higher levels in large neurons than small DRG neurons, while sodium channel mRNA II is variably expressed, with most cells lacking or exhibiting low levels of detectable signal of these mRNAs and limited numbers of neurons with moderate expression levels. DRG neurons generally exhibit negligible or low levels of hybridization signal for sodium channel mRNA III. Sodium channel mRNAs Na6 and NaG show similar patterns of expression, with most large and many medium DRG neurons exhibiting high levels of expression. The mRNA for the rat cognate of human sodium channel hNE-Na is detected in virtually every DRG neuron; most cells in all size classes exhibit moderate or high levels of hNE-Na expression. Sodium channel SNS mRNA is expressed in all size classes of DRG neurons, but shows greater expression in small and medium DRG neurons than in large neurons. The mRNA for the rat cognate of mouse sodium channel mNa 2.3 is not detected, or is detected at low levels, in most DRG neurons, regardless of size, although moderate expression is detected in some neurons. Sodium channel beta 1- and beta 2-subunit mRNAs exhibit similar expression patterns; they are detected in most DRG neurons, although the level of expression tends to be greater in large neurons than in small neurons. RT-PCR and in situ hybridization of intact adult DRG showed a similar pattern of expression of sodium channel mRNAs to that observed in DRG neurons in vitro. These results demonstrate that adult DRG neurons express multiple sodium channel mRNAs in vitro and in situ and suggest a molecular basis for the biophysical heterogeneity of sodium currents observed in these cells.
Brain Res Mol Brain Res 1996 Dec 31
PMID:Spinal sensory neurons express multiple sodium channel alpha-subunit mRNAs. 903 25

The expression of sodium channel alpha-subunit mRNAs I, II, III, NaG, Na6 and hNE (PN1) was examined in developing (E17-P30) hippocampus, cerebellum, spinal cord and dorsal root ganglia using non-isotopic in situ hybridization cytochemistry. The results showed distinct patterns of expression for each of the sodium channel mRNAs with maturation of the nervous system. In the hippocampus, sodium channel mRNA I was not detected at any developmental time, while mRNA II showed increasing hybridization signal between E17 and P30. Sodium channel mRNA III was more prevalent at late embryonic and early postnatal times, and was barely detectable at P30. The transcript for NaG showed transient expression between P2 and P15, being expressed at low levels at E17 and not being detectable at P30. Sodium channel mRNA Na6 exhibited a high level of expression between E17 and P15 in the hippocampal formation, with an attenuation of the signal by P30. hNE (PN1) mRNA was not detected in the hippocampus at any time examined. In the cerebellum, sodium channel mRNA I was not detected at E17 or P2, but became detectable in Purkinje cells at P15 and continued to show a low level of expression in these cells at P30. mRNA I was not detected at any time examined in granule cells of the cerebellum. Sodium channel mRNA II exhibited increasing expression in the developing cerebellum, and showed increasing signal in Purkinge cells beginning on P2 and granule cells on P15. Sodium channel mRNA III was down-regulated with development in the cerebellum, although mRNA III was readily detected at E17, it was not detected in any layers of the cerebellum by P15. NaG mRNA showed a peak of expression at P2, and was present at low levels at E17 and P15 and not detectable at P30. Na6 mRNA was highly expressed in the E17 cerebellum; this mRNA was present at high levels in Purkinje cells throughout development, although in granule cells the signal was attenuated at P15-P30. Sodium channel hNE (PN1) mRNA was not detected in the cerebellum at any time in development. In the spinal cord, sodium channel mRNA I showed increasing expression beginning at P2 and was highly expressed, particularly in ventral motor neurons, by P30. Sodium channel II mRNA was detected at all stages of development in the spinal cord; in contrast, mRNA III was detected at E17 and P2, but showed very low levels of expression by P30. NaG mRNA exhibited a transient expression in spinal cord at P2, but was not detectable at E17 and P30. Na6 mRNA was detectable at very low levels at E17 and became highly expressed at P2, prior to a reduction of the signal at P15 and P30. hNE (PN1) mRNA was not detected in the spinal cord at any time in development. In the dorsal root ganglia, sodium channel I mRNA hybridization signal was detected in DRG neurons at P2, with slightly increased levels at P15 and P30. Sodium channel II mRNA exhibited a relatively constant, moderate level of expression at all developmental ages. Sodium channel III mRNA was highly expressed in DRG neurons at E17 but was down-regulated with further development so that it was not detectable by P30. NaG mRNA was strongly expressed by some DRG neurons at all stages of development from E17 to P30; in general the level of NaG labelling was greater in larger neurons than in smaller neurons. Na6 mRNA showed increasing expression with development in DRG neurons; at E17, low levels of Na6 mRNA were detected and by P15 to P30 high levels of expression were present in some neurons. hNE (PN1) mRNA was present in DRG neurons at P2, and was up-regulated with further development so that by P30 hNE (PN1) was expressed in all DRG neurons sizes. These results demonstrate that sodium channel alpha-subunit mRNAs I, II, III, NaG, Na6 and hNE (PN1) exhibit distinct spatial and temporal patterns of expression in nervous tissue, and suggest that the expression of the sodium channel alpha-subunits is differentially regulated. (ABSTRACT TRUNCATED)
Brain Res Mol Brain Res 1997 Apr
PMID:Sodium channel alpha-subunit mRNAs I, II, III, NaG, Na6 and hNE (PN1): different expression patterns in developing rat nervous system. 910 72

This study sought to evaluate the use of tetrazolium salt XTT reduction as an indicator of valvular viability in a cryoprocessed porcine cardiac homograft model. The XTT tetrazolium assays was based on the metabolic reduction of Sodium 3'-[1-(phenylamino-carbonyl)-3,4-Tetrazolium]-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate. The relationship between XTT reduction and: (1) leaflet tissue with various weight (n = 24); (2) morphometric evaluation (n = 30); (3) cadaveric ischemic intervals (n = 30); (4) freeze-thawing (n = 30) has been studied. The measurement of XTT reduction were significantly correlated with the weight of cardiac leaflets, in the range of 30 to 180mg (y=0.015x-0.063; r=0.99). Compared to morphometry of valvular damage, the reduction of mitochondrial enzymatic activity in cardiac leaflets was correlated with matrix cells without irreversible damage (r=0.89, P<0.005). The depletion of XTT reduction occurred dependent of ischemic time intervals. In general, freeze-thawing reduced more than 20% activity of mitochondrial dehydrogenase. We concluded that XTT tetrazolium assay is highly sensitive to determine valvular injury. The study demonstrated its potential for testing of cryopreserved cardiac valve.
J Mol Cell Cardiol 1997 Apr
PMID:XTT-colorimetric assay as a marker of viability in cryoprocessed cardiac valve. 916 Aug 70

Pyrimidines and purine (deoxy)nucleotides are the building blocks of DNA and RNA. Nucleoside diphosphate sugars, e.g. UDP-glucose, are the reactive intermediates in the synthesis of nearly all glycosidic bonds between sugars. In mammals the requirement for pyrimidines is met by UMP de novo synthesis and, to a greater or lesser extent, by salvage of free nucleosides. The exceptional compartmentation of the de novo synthesis with respect to mitochondrially-bound dihydroorotate dehydrogenase ('DHOdehase' or 'DHODH', EC 1.3.99.11) is one focus of the present work. DHODH activity was determined by the dihydroorotate-dependent oxygen consumption or by the UV absorption of the product orotate with mitochondria isolated from rodent and porcine tissues. For comparison, the cytochrome c and choline-dependent oxygen consumption of mitochondria from different tissues was measured. The highest specific activity of the rat DHODH was found in liver (2.3 x 10(-3) mumol/min x mg protein) > kidney > heart. The application of known enzyme inhibitors Brequinar Sodium and Leflunomide for DHODH and sodium cyanide for cytochrome c oxidase verified the specificity of the activity tests used. The relation of DHODH activity versus that of cytochrome c oxidase revealed the lowest ratios in heart mitochondria and the highest in liver mitochondria. Since disorders in the mitochondrial energy metabolism could entail severe impairment of pyrimidine biosynthesis via respiratory-chain coupled DHODH, it is suggested to include improvement of pyrimidine nucleotide status in therapy protocols.
Mol Cell Biochem 1997 Sep
PMID:Dihydroorotat-ubiquinone oxidoreductase links mitochondria in the biosynthesis of pyrimidine nucleotides. 930 76

1. We studied the effects of selective chronic sodium depletion of chloride depletion on atrial natriuretic peptide receptor number in the subfornical organ and paraventricular nucleus of young rats. 2. Sodium or chloride depletion decreased plasma levels of atrial natriuretic peptide, increased plasma renin activity, and induced extracellular fluid volume contraction. Chloride depletion induced more significant changes in extracellular fluid volume contraction than sodium depletion. 3. In the subfornical organ, atrial natriuretic peptide receptor number significantly decreased (30%) after sodium depletion, while chloride depletion induced a smaller, not statistically significant decrease. Conversely, atrial natriuretic peptide receptors located in the paraventricular nucleus of young rats were not significantly affected by sodium or chloride depletion. 4. Water deprivation reversed the decrease in atrial natriuretic peptide receptors produced by sodium depletion. Water-deprived sodium-depleted rats actually had higher numbers of atrial natriuretic peptide receptors in the subfornical organ than control rats. These changes were associated with severe extracellular fluid volume contraction and up regulation of brain vasopressin mRNA steady-state levels. Thus, the direction of change in the number of subfornical organ atrial natriuretic peptide receptors was dependent on the degree of extracellular fluid volume contraction. 5. Our results suggest that atrial natriuretic peptide receptors located in the subfornical organ, and not in the paraventricular nucleus, are selectively regulated by sodium depletion and extracellular fluid volume contraction.
Cell Mol Neurobiol 1997 Oct
PMID:Selective chronic sodium or chloride depletion specifically modulates subfornical organ atrial natriuretic peptide receptor number in young rats. 935 88

Familial factors are believed to be important in determining the high sodium-lithium countertransport activity (defined as >0.40 mmol Li/(h x l cell) at external sodium concentration of 140 mmol/L (Nae 140)) which is observed in a proportion of patients with essential hypertension. However, environmental factors such as pregnancy and dyslipidemia also affect activity. High sodium-lithium countertransport activity (Nae 140) in essential hypertension is mainly due to a low Michaelis constant (Km) and is associated with a high Vmax/Km ratio. In contrast, dyslipidemias affect Vmax. This study aimed to determine if there was evidence that Km and Vmax/Km ratios are influenced by familial factors. Sodium-lithium countertransport kinetics were measured in the 47 first degree relatives of 12 hypertensive probands with abnormal sodium-lithium countertransport kinetics and 35 normotensive control subjects. Sodium-lithium countertransport was measured as Na-stimulated Li efflux from lithium loaded erythrocytes. The relatives had significantly reduced Km and increased Vmax/Km compared to normal subjects. Eleven relatives had high sodium-lithium countertransport activity (Nae 140), associated with low Km and high Vmax/Km. The 14 relatives that were hypertensive had abnormalities of sodium-lithium countertransport kinetics. The results of this study suggest that familial factors are important in determining the Km and Vmax/Km of sodium-lithium countertransport activity. Studies aimed at determining the inheritance of sodium-lithium countertransport and its use as an intermediate phenotype of essential hypertension must measure its kinetic determinants to reduce the risk of confounding effects from other variables.
Biochem Mol Med 1997 Oct
PMID:Na-Li countertransport kinetics in the relatives of hypertensive patients with abnormal Na-Li countertransport activity. 936 6

Developmental changes in the functional properties of thoracic aorta were examined in neonatal and adult guinea-pigs. Norepinephrine-induced contractions of the neonatal aortic rings were markedly enhanced by removal of the endothelium, whereas those of the adult rings were only slightly enhanced. Carbachol induced endothelium-dependent relaxation to a similar extent in both neonatal and adult aortic rings precontracted with 30 microM norepinephrine. A23187 induced endothelium-dependent relaxation in the adult aortic rings precontracted with 30 microM norepinephrine, whereas it failed to induce the relaxation in the neonatal aortic ring. Sodium nitropurusside induced endothelium-independent relaxation to a similar extent in both neonatal and adult aortic rings precontracted with 30 microM norepinephrine. The endothelium-dependent relaxation induced by carbachol and by A23187 were inhibited either by NG-nitro-L-arginine or by methylene blue, but not by indomethacin, indicating that both the relaxations were mediated by nitric oxide, but not by prostacyclin. These results suggest that, although the neonatal endothelium of the guinea-pig aorta is capable of releasing nitric oxide, the mechanisms underlying the synthesis and/or release of nitric oxide may be different between the neonatal and adult endothelium.
Res Commun Mol Pathol Pharmacol 1997 Oct
PMID:Difference in the endothelium mediated effects of A23187 on thoracic aorta between neonatal and adult guinea pigs. 943 15

Sodium-dependent transport into astrocytes is critical for maintaining the extracellular concentrations of glutamate below toxic levels in the central nervous system. In this study, the expression of the glial glutamate transporters GLT-1 and GLAST was studied in primary cultures derived from cortical tissue. In primary astrocytes, GLAST protein levels were approximately one half of those observed in cortical tissue, but GLT-1 protein was present at very low levels compared with cortical tissue. Maintenance of these astrocytes in medium supplemented with dibutyryl-cAMP (dbcAMP) caused a dramatic change in cell morphology, increased GLT-1 and GLAST mRNA levels approximately 5-fold, increased GLAST protein approximately 2-fold, and increased GLT-1 protein >/=8-20-fold. These increases in protein expression were accompanied by 2-fold increases in the Vmax and Km values for Na+-dependent L-[3H]glutamate transport activity. Although GLT-1 is sensitive to inhibition by dihydrokainate in heterologous expression systems, no dihydrokainate sensitivity was observed in astrocyte cultures that expressed GLT-1. Biotinylation with a membrane-impermeant reagent, separation of the biotinylated/cell surface proteins, and subsequent Western blotting demonstrated that both GLT-1 and GLAST were present at the cell surface. Coculturing of astrocytes with neurons also induced expression of GLT-1, which colocalized with the glial specific marker, glial fibrillary acidic protein. Neurons induced a small increase in GLAST protein. Several studies were performed to examine the mechanism by which neurons regulate expression of the glial transporters. Three different protein kinase A (PKA) antagonists did not block the effect of neurons on glial expression of GLT-1 protein, but the addition of dbcAMP to mixed cultures of neurons and astrocytes did not cause GLT-1 protein to increase further. This suggests that neurons do not regulate GLT-1 by activation of PKA but that neurons and dbcAMP regulate GLT-1 protein through convergent pathways. As was observed with GLT-1, the increases in GLAST protein observed in cocultures were not blocked by PKA antagonists, but unlike GLT-1, the addition of dbcAMP to mixed cultures of neurons and astrocytes caused GLAST protein to increase approximately 2-fold. Neurons separated from astrocytes with a semipermeable membrane increased GLT-1 protein, indicating that the effect of neurons was mediated by a diffusible molecule. Treatment of cocultures with high concentrations of either N-methyl-D-aspartate or glutamate killed the neurons, caused GLT-1 protein to decrease, and caused GLAST protein to increase. These studies suggest that GLT-1 and GLAST protein are regulated independently in astrocyte cultures and that a diffusible molecule secreted by neurons induces expression of GLT-1 in astrocytes.
Mol Pharmacol 1998 Mar
PMID:Regulation of the glial Na+-dependent glutamate transporters by cyclic AMP analogs and neurons. 949 99


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