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At least 289 records · Page 16Linked to original sources
PubMed1977

Dependence of cytoplasmic on mitochondrial protein synthesis in K. lactis CBS 2360. II. Genetic studies.

A few eryR mutants independently isolated from K. lactis CBS 2360 display a conditional lethal phenotype at the temperature of 36 degrees C. In addition to drug resistance, also conditional lethality shows a non-Mendelian pattern of inheritance and is affected by exposure of the cells to Ethidium Bromide, indicating that in this yeast mitochondrial DNA controls cell viability. The results obtained from biochemical analysis suggest that the cellular functions in which are involved the gene products of the mitochondrial mutants analized are cytoplasmic protein and RNA syntheses.

Cytoplasm↗
PubMed1989

Stimulation of Na+,K+-ATPase activity in certain membranes of the rat central nervous system (CNS) by acute administration of desipramine (DMI).

1. The activities of ATPase in rat CNS were studied 3 hr after administration of the noradrenaline uptake inhibitor, desipramine (DMI: 10 mg.kg-1, i.p.). Na+K+-ATPase activity significantly increased after DMI in the whole particulate from hypothalamus and mesencephalus but no changes in frontal cortex or in pons-medulla oblongata areas were found. This increase was prevented when the animals were pretreated with the noradrenergic neurotoxic N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4). 2. Purified membrane fractions from hypothalamus were obtained by differential and sucrose gradient centrifugation (0.8-1.2 M sucrose). It was observed that after DMI, Na+,K+-ATPase activity increased only in the membranous fraction lying at 0.9 M sucrose. 3. Mg2+- or Ca2+-ATPase activities were not modified by DMI treatment. 4. Citalopram, a specific serotonergic uptake inhibitor, did not affect ATPase activities. 5. The results obtained could indicate that DMI acute administration selectively stimulates Na+,K+-ATPase activity of certain membranes of the CNS after an increase in the concentration of the noradrenergic neurotransmitter in the synaptic gap.

Animals↗
PubMed1998

Motor representation of the hand in the human cortex: an f-MRI study with a conventional 1.5 T clinical unit.

The purpose of this study was to show a gradient of possible bilateral activation for movements of the non-dominant vs. dominant hand, as well as for areas involved in complex vs. simple hand movements. A standard 1.5 T magnetic resonance imaging (MRI) system has been utilized to localize the cortical motor hand areas, using the blood oxygen level dependent contrast (BOLDc) technique and single-section fast low-angle shot (FLASH) imaging. Ten normal right-handed subjects volunteered for the study. The motor tasks consisted of simple (flexion-extension) finger movements of either hand, and complex movements (finger-to-thumb opposition in a repeating, pre-planned sequence) of the non-dominant hand. Simple movements caused contralateral activation of the primary motor area (MA); ipsilateral activation was observed for the non-dominant hand only. Supplementary motor area (SMA) was also activated, with a clear contralateral prevalence. The ratio of bilateral activation of MA did not change with complex movements of the non-dominant hand, while SMA as well as lateral premotor area were largely bilaterally activated in this task. In conclusion, the ipsilateral MA is activated for movements--even simple--performed with the non-dominant hand. There is widespread functional activity, involving both contralateral and ipsilateral SMA, for complex movements.

Adult↗
PubMed1981

Effect of CDP-choline on the biosynthesis of nucleic acids and proteins in brain regions during hypoxia.

The effect of CDP-choline on the in vivo incorporation of labeled precursors into DNA, RNA, and proteins in cerebral hemispheres, cerebellum, and brainstem of guinea pigs after hypoxic treatment was studied. The labeling of macromolecules extracted from the various subcellular fractions of these brain regions was also determined. Hypoxic treatment affected macromolecular labeling to a different extent in the three brain regions examined. CDP-choline treatment was not able to reverse the effect of hypoxia on DNA labeling, but it was able to remove the effect of hypoxia on RNA and protein labeling. The action of CDP-choline was particularly evident on the labeling of RNA in nuclei and mitochondria of the cerebellum and on the labeling of proteins in microsomes of the three brain regions examined.

Animals↗
PubMed1981

Axonal transport of phospholipids in rabbit optic pathway.

The uptake of different labeled precursors, their incorporation into lipids, and transport along the rabbit optic pathway [ipsilateral retina and optic nerve (ON), and contralateral optic tract (OT), lateral geniculate body (LGB), and superior colliculus (SC)] were investigated. Albino rabbits were used. The following radioactive precursors ,either combined or separately, dissolved in 50 microliter of saline containing 15% BSA, were injected into vitreous body: [2-3H]glycerol (50 microCi), [1-14C]palmitate (15 microCi), and [1-14C]linoleate (7.5 microCi). Animals were killed at different time intervals from 1 hr up to 24 days. The radioactivity of total lipids and of different phospholipid classes from total tissue was measured. One hour after administration of precursors, the radioactivity into the retina was high and the incorporation of [3H]glycerol and [14C]palmitate increased until 12 hr and 24 hr, respectively. The incorporation of [14C]linoleate reached a maximum on the second day. The phospholipids of LGB and SC were intensively labeled after 4-8 hr, and their radioactivity increased up to the 10th day after injection, independent of the precursor employed. The results obtained indicate that the labeled hydrophilic and hydrophobic precursors used were actively incorporated into the retina, The phospholipids were later transported at a rapid rate along the optic pathway.

Animals↗
PubMed1983

Myelination of regenerating sciatic nerve of the rat: lipid components and synthesis of myelin lipids.

Changes of lipid, free fatty acid, protein, DNA, and RNA content in proximal and distal segments of regenerating sciatic nerve, from 14 to 120 days after crush, were determined. During the early stage of Wallerian degeneration, a marked decrease of phospholipid, cerebroside and sulfatide content and, in contrast, a marked increase of protein, DNA, RNA, and free fatty acid content, in the distal segment of crushed nerve compared to control, was observed. A gradual increase of phospholipid, cerebroside, and sulfatide levels, approaching normal values, and a gradual slope in the increase of protein, DNA, RNA, and free fatty acid levels over the ensuing time periods of regeneration was seen. Total cholesterol content was relatively constant during regeneration, slightly increasing at day 120. The activity of 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) of myelin fraction purified from distal segment of regenerating sciatic nerve showed a significant increase in the 30-120 day regenerating period. A marked increase of the incorporation of [2-3H]glycerol and of [Me-14C]choline into myelin lipids of distal segment of regenerating nerve, was found. Labeling of myelin lipids with [3H]oleic acid (injected intravenously seven days before crush) support the evidence that a similar pattern of degeneration exists between two different types of trauma, i.e. nerve crush or cut. The findings suggest that, in the distal segment of crushed nerve, the lipid content as well as the myelin lipid synthesis increase as the regeneration period proceeds.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1981

Effect of hypoxia on nucleic acid and protein synthesis in different brain regions.

The incorporation of [methyl-3H]thymidine into DNA, of [5-3H]uridine into RNA, and of [1-14C]leucine into proteins of cerebral hemispheres, cerebellum, and brainstem of guinea pigs after 80 hr of hypoxic treatment was measured. Both in vivo (intraventricular administration of labeled precursors) and in vitro (tissue slices incubation) experiments were performed. The labeling of macromolecules extracted from the various subcellular fractions of the above-mentioned brain regions was also determined. After hypoxic treatment the incorporation of the labeled precursors into DNA, RNA, and proteins was impaired to a different extent in the three brain regions and in the various subcellular fractions examined; DNA and RNA labeling in cerebellar mitochondria and protein labeling in microsomes of the three brain regions examined were particularly affected.

Animals↗
PubMed1984

Myelination process in the rat sciatic nerve during regeneration and development: molecular species composition and acyl group biosynthesis of choline-, ethanolamine-, and serine-glycerophospholipids of myelin fractions.

The content of alkenyl-acyl, alkyl-acyl and diacyl types of the three major myelin glycerophospholipids such as PtdCho, PtdEtn and PtdSer was determined in myelin fractions prepared from sciatic nerve segments of rats at 12, 25 and 45 days after birth, and of adult rats (6-month-old) 90 days after crush injury. The biosynthesis and metabolic heterogeneity of lipid classes and types were also studied by incubation with [1-14C] acetate of nerve segments of young rats at different ages as well as crushed and sham-operated control nerve segments of adult rats. The analysis of composition and positional distribution in major individual molecular species extracted from light myelin and myelin-related fraction suggest that the metabolism of alkenyl-acyl-glycerophosphorylethanolamines and unsaturated species of PtdCho and PtdSer may not be regulated in the same manner during peripheral nerve myelination of developing rat and remyelination of regenerating nerve in the adult animal. The 14C-radioactivity incorporation into lipid classes and alkyl and acyl moieties of the three major phospholipids of sciatic nerve segments during the developmental period investigated revealed that Schwann cells were capable of synthesizing acyl-linked fatty acids in both myelin fractions at a decreasing rate and with different patterns during development. In regenerating sciatic nerve of adult animals the labeling of myelin lipid classes and types of remyelinating nerve segment distal to the crush site was markedly higher than that of sham-operated normal one; however, the magnitude and the pattern of the specific radioactivity never approached those observed during active myelination of the nerve in young animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1982

Transfer of axonally transported phospholipids into myelin isolated from the rabbit optic pathway.

The contribution of the axonal transport to the biosynthesis of myelin phospholipids was investigated in the rabbit optic pathway. A double labeling technique was used. The same animals were injected with one isotope intravitreally and the other intraventricularly. This procedure allows double labeling of the optic nerves, optic tracts, lateral geniculate bodies (LGB), and superior colliculus (SC). The precursors simultaneously injected were: [1-14C]palmitate (15 microCi intravitreally in both eyes or 50 microCi intraventricularly) and [2-3H]glycerol (50 microCi intravitreally in both eyes of 100 microCi intraventricularly). Twenty four hours and 10 days after the injections, myelin was purified from pooled optic nerves and optic tracts as well as from pooled LGBs or SCs. The phospholipids were extracted and then separated by thin-layer chromatography; the specific radioactivity of the various classes of phospholipids was determined. Using both administration routes of C- or 3H-precursors, the distribution of label and specific radioactivity of myelin phospholipids in the retina and in all other optic structures were very similar. Phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine + phosphoinositol were preferentially labeled with both precursors. These results suggest that, in the rabbit optic pathway the phospholipids synthesized in the retinal ganglion cells and transported along the axons, could undergo transaxonal transfer into myelin.

Animals↗
PubMed1983

Labeling of RNA in young and adult rat brain: evidence for different RNA processing.

The labeling of RNA in young and adult rat brain has been studied by measuring in vitro (tissue slices incubation) the incorporation of labeled uridine into RNA of total tissue and of the various subcellular fractions purified from cerebral hemispheres of 1- and 10-month-old rats. Gel electrophoretic analysis of the newly synthesized nuclear and microsomal RNA was also accomplished. An active metabolism of RNA in adult animals was found; moreover, distinct differences in ribosomal RNA processing in cerebral hemispheres of 1- and 10-month-old rats, with a more rapid processing in the brain of adult animals, were obtained.

Aging↗
PubMed1994

Longitudinal study of cerebral blood flow following early or delayed surgery for ruptured intracranial aneurysms.

Out of a series of 43 cases operated on for ruptured intracranial aneurysms over a 12-month-period, 32 patients were followed up to 12 months postoperatively with repeated evaluations of cerebral blood flow, using the Xenon133 inhalation technique. No statistically significant differences in cerebral perfusion were detected between the subgroups of good-grade patients, who were submitted respectively to early, or delayed surgery. Depression of flow in the affected hemisphere of poor-grade patients was principally related to the preoperative occurrence of an intracerebral haematoma. The overall results were not consistent with the hypothesis that early surgical intervention results in long-lasting effects on the cerebral circulation.

Adult↗
PubMed1986

A comparison of tumor-related antigens in male and female breast cancer.

A retrospective analysis was undertaken in which 15 female and 15 male breast cancers were matched by age, stage, estrogen receptor status, and histologic type. Our protocol compares male and female breast cancers for reactivity with antibodies against tumor-associated antigens known to be present on female breast cancer cells. Formalin-fixed sections of each primary tumor were reacted in the ABC immunoperoxidase assay against antibodies B72.3 and DF.3 and an antibody to the ras p21 antigen. Reactivity to B72.3 and DF.3 was similar. However, the ras p21 antigen was expressed to a significantly greater extent in female breast cancers (p = .0008). Thus, although there are similarities in antigenic phenotype of male and female breast cancers, some female breast cancers may have a different pathogenesis as demonstrated by increased amounts of a specific oncogene product.

Adult↗
PubMed1996

Conversion of cysteinyl residues to unnatural amino acid analogs. Examination in a model system.

Improved and efficient techniques have led to an explosive growth in the application of site-directed mutagenesis to the study of enzymes. However, the limited availability of only those 20 amino acids that are translated by the genetic code has prevented the systematic variation of an amino acid's properties in order to define more precisely its role in the catalytic mechanism of an enzyme. An approach is being examined that combines the high specificity of site-directed mutagenesis with the flexibility of chemical modification to overcome these limitations. A set of reagents has been synthesized and reacted with a cysteine model to produce a series of amino acid structural analogs at appreciable rates and in good overall yields. The selective incorporation of these analogs in place of important functional amino acids in a protein will allow a more detailed examination of the role of that amino acid.

Amino Acids↗