Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1832526 (PCC)
 5,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The area of the corpus callosum (CC) on midsagittal spin-echo sequence magnetic resonance (MR) scans was measured in 64 normal subjects and 12 patients with Alzheimer's disease (AD). The normal subjects consisted of 32 males and 32 females, aged 25 to 83 years old. There was no significant age difference between males and females. Fifty-five out of 64 subjects were right-handed (RH) and 9 were left-handed or ambidextrous (NRH). Among patients with AD, 5 were males and 7 were females, aged 53 to 79 years old. Diagnosis of AD was performed mainly based on clinical history, magnetic resonance image (MRI) and positron emission tomographic findings. The outline of the CC on midsagittal MR film was traced and the total callosal sectional area (CCT) as well as the anterior half (CCA), posterior half (CCP) and posterior 5th or splenium (CCS) area measurements were performed using a planimeter. In either normal males or females, the CCA showed a significant negative correlation with age, but the CCP and the CCS did not correlate with age. Total CC (CCT) area was 691.2 +/- 91.0 sq. mm for the whole group and no difference was found between males and females. When the CC area was normalized with respect to the midsagittal area of the supratentorial portion of the brain (MSB), females were found to have a larger CC than males. No portion of the CC area was significantly different between RH and NRH subjects in absolute or normalized measures.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Size of the corpus callosum in normal subjects and patients with Alzheimer's disease--magnetic resonance imaging study]. 274 78

We have previously shown that lesion of the posterior cingulate cortex (CCP) but not of the anterior cingulate cortex (CCA), produced learning and memory deficits. As a first evaluation of the functional anatomical basis of this dissociation, we used the quantitative [14C]2-deoxyglucose method and electrical brain stimulation to determine the functional connections of the CCA and CCP in mice. CCP stimulation (but not CCA stimulation) produced significant metabolic increases in the hippocampal formation and in the subicular complex. This result is consistent with the hypothesis that learning and memory deficits following CCP lesion may be due to the disruption of functional neural pathways between the CCP and hippocampal structures.
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PMID:Quantitative [14C]2-deoxyglucose study of a functional dissociation between anterior and posterior cingulate cortices in mice. 277 Nov 67

We have studied the effect of the 3' terminal CCA sequence in precursors of tRNAs on catalysis by the RNase P RNA or the holoenzyme from the cyanobacterium Synechocystis sp. PCC 6803 in a completely homologous system. We have found that the absence of the 3' terminal CCA is not detrimental to activity, which is in sharp contrast to what is known in other bacterial systems. We have found that this is also true in other cyanobacteria. This situation correlates with the anomalous structure of the J15/16 loop in cyanobacteria, which is an important loop in the CCA interaction in Escherichia coli RNase P, and with the fact that cyanobacteria do not code the CCA sequence in the genome but add it posttranscriptionally. Modification of nucleotides 330-332 in the J15/16 loop of Synechocystis RNase P RNA from GGU to CCA has a modest effect on kcat for CCA-containing substrates and has no effect on cleavage-site selection. We have developed a direct physical assay of the interaction between RNase P RNA and its substrate, which was immobilized on a filter, and we have determined that Synechocystis RNase P RNA binds with better affinity the substrate lacking CCA than the substrate containing it. Our results indicate a mode of substrate binding in RNase P from cyanobacteria that is different from binding in other eubacteria and in which the 3' terminal CCA is not involved.
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PMID:Substrate binding and catalysis by ribonuclease P from cyanobacteria and Escherichia coli are affected differently by the 3' terminal CCA in tRNA precursors. 1035 70

Biosynthesis of transfer RNA requires processing from longer precursors at the 5'- and 3'-ends. In eukaryotes, in archaea, and in those bacteria where the 3'-terminal CCA sequence is not encoded, 3' processing is carried out by the endonuclease RNase Z, which cleaves after the discriminator nucleotide to generate a mature 3'-end ready for the addition of the CCA sequence. We have identified and cloned the gene coding for RNase Z in the cyanobacterium Synechocystis sp. PCC 6803. The gene has been expressed in Escherichia coli, and the recombinant protein was purified. The enzymatic activity of RNase Z from Synechocystis has been studied in vitro with a variety of substrates. The presence of C or CC after the discriminator nucleotide modifies the cleavage site of RNase Z so that it is displaced by one and two nucleotides to the 3'-side, respectively. The presence of the complete 3'-terminal CCA sequence in the precursor of the tRNA completely inhibits RNase Z activity. The inactive CCA-containing precursor binds to Synechocystis RNase Z with similar affinity than the mature tRNA. The properties of the enzyme described here could be related with the mechanism by which CCA is added in this organism, with the participation of two separate nucleotidyl transferases, one specific for the addition of C and another for the addition of A. This work is the first characterization of RNase Z from a cyanobacterium, and the first from an organism with two separate nucleotidyl transferases.
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PMID:Sequence-dependent cleavage site selection by RNase Z from the cyanobacterium Synechocystis sp. PCC 6803. 1605 5

Three groups of male rats were submitted to an intermittent hypobaric hypoxia (IHH) program for 22 days (4 h/day, 5 days/week) in a hypobaric chamber at a simulated altitude of 5000 m. Hearts were removed at the end of the program (H group) and 20 and 40 days later (P20 and P40 groups). A control group (C) was maintained at sea-level pressure. Transverse sections from myocardium were cut and histochemically stained in order to measure fiber morphometry and capillaries. We observed a progressive increase from C to H to P20 animals in capillary (4124 to 4733 to 4816 capillaries/mm(2)) and fiber densities (2844 to 3125 to 3284 fibers/mm(2)) associated with significant reductions in fiber area (273, 235, and 227 microm(2)), perimeter (69, 64, and 62 microm), and diffusion distances (18.2, 16.9, and 16.6 microm). The most significant differences between C and hypoxic groups were found when morphometrical and vascular fiber parameters were combined. The myocardium of the latter had more capillaries per fiber area and per fiber perimeter. These findings indicate that the IHH program elicits an adaptive response of rat myocardium to a more efficient O2 delivery to mitochondria of cardiac muscle cells. Capillarization and fiber morphometric changes showed marked differences over time. In all cases, P20 had higher capillarization parameters and fiber morphometry reductions than H, thus indicating that a delay of about 20 days exists after the hypoxic stimulus ceases to reach complete angiogenesis and fiber morphometry changes. However, P40 animals showed a recovery to basal values of the parameters related to fiber morphometry (area, perimeter, and diffusion distances), but maintained high capillarity values (capillary density, NCF, CCA, CCP).
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PMID:Capillary supply and fiber morphometry in rat myocardium after intermittent exposure to hypobaric hypoxia. 1808 8

Increasing evidence has shown that DNA methylation is involved in gene regulation in prokaryotes. However, there have been very limited reports about the role of DNA methylation in regulation of gene expression and physiological functions in cyanobacteria. In Synechocystis sp. PCC 6803, four genes on the plasmid pSYSX are predicted to encode the type I restriction-methylation system, slr6095 and slr6096 for the M subunit, slr6097 for the S subunit and slr6102 for the R subunit. Compared to the wild type, slr6095, slr6096, and slr6097 mutants lacked the GGm6AN7TTGG/CCAm6AN7TCC methylation in genomic DNA. Transcriptomic analysis indicated that 171 genes were reproducibly up- or down-regulated in all three mutants relative to the wild type. The changed expression of some genes, including sll1356 for glycogen phosphorylase (GlgP), was associated with the loss of GGm6AN7TTGG/CCAm6AN7TCC methylation in the coding regions or the upstream non-coding sequences. Inactivation of slr6095, slr6096, or slr6097 increased the expression of sll1356 and the GlgP activity but lowered the glycogen content. These results indicated that the DNA methylation by a type I RM system could alter the expression of certain genes and physiological functions in Synechocystis sp. PCC 6803.
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PMID:Effects of a Type I RM System on Gene Expression and Glycogen Catabolism in Synechocystis sp. PCC 6803. 3258 32