Biomedical subjects

M Mata

Publications and source records attributed to M Mata.

At least 91 records · Page 5Linked to original sources

PubMed1987

Ultrastructural distribution of Ca++ within neurons. An oxalate pyroantimonate study.

We used the oxalate-pyroantimonate technique to determine the ultrastructural distribution of Ca++ in neurons of the rat sciatic nerve. The content of the precipitate was confirmed by X-ray microanalysis and appropriate controls. In the cell bodies of the dorsal root ganglia, Ca++ precipitate was found in the Golgi, mitochondria, multivesicular bodies and large vesicles of the cytoplasm but not in lysosomes, and was prominently absent from regions of rough endoplasmic reticulum and ribosomes. It was seen in the nucleus but not in the nuclear bodies or nucleolus. Within the axon itself, Ca++ precipitate was also found sequestered in mitochondria and smooth endoplasmic reticulum. In addition Ca++ precipitate found diffusely throughout the axoplasm exhibited a discrete and heterogeneous distribution. In myelinated fibers the amount of precipitate decreased predictably in the axoplasm beneath the Schmidt-Lanterman cleft and in the paranodal regions at the nodes of Ranvier. This correlated with the presence of dense precipitate in the Schmidt-Lanterman cleft themselves and in the paranodal loops of myelin. Intracytoplasmic ionic Ca++ is maintained at 10(-7) M by balanced processes of influx, sequestration and extrusion. The irregular distribution of Ca++ precipitate in the axoplasm of myelinated fibers suggests that there may be specific regions of preferential efflux across the axolemma.

Animals↗

PubMed1987

Retrograde axonal transport in rat sciatic nerve after nerve crush injury.

We investigated the quantitative alterations in retrograde transport of proteins following a nerve crush injury using the 3H N-succinimidyl propionate (3H NSP) method in rat sciatic nerve. After subepineurial injection of 3H NSP into the nerve the amount of radioactively labeled proteins accumulating in the cell bodies of the motor and sensory neurons was determined 1 day or 7 days later in nerves which had been crushed distal to the injection site 1, 3, 5, 7, or 33 days prior to 3H NSP labeling. One day accumulation in the DRG and spinal cord was not altered by nerve crush. Seven day accumulation in the DRG was initially slightly increased, then fell to 73% of control by 7 days, remaining reduced 33 days after crush. Seven day accumulation in the spinal cord was reduced to 25% of control 1 day after crush and remained at that low level except for 5 days post-crush when a normal amount of labeled protein was transported to the spinal cord. The time course of these changes suggests that quantitative alterations in retrograde transport may be involved in the long-term trophic interactions between the cell body and periphery, but are too slow to account for the earliest perikaryal responses to injury. In addition, the difference between the alterations of retrograde transport in motor and sensory neurons may reflect fundamental differences in the composition of retrograde transport in those different systems.

Animals↗

PubMed1987

The distribution of serum albumin in rat peripheral nerve.

To clarify the nature of the blood-nerve barrier (BNB) in excluding serum proteins from peripheral nerve endoneurium, we studied the ultrastructural distribution of albumin in peripheral nerve using light and electron microscopic immunocytochemistry. We found that serum albumin is commonly found within the endoneurium, but that it is not normally found intraaxonally. After subperineurial injection of labeled albumin, the albumin redistributed within intrafascicular clefts towards the perivascular spaces and the perineurium. These results suggest that, contrary to previous evidence, axons are exposed to serum proteins in normal nerves, and implies that they may be subject to interaction with abnormal proteins or altered serum proteins without any disruption of the BNB.

Animals↗

PubMed1987

Molecular characterization and comparison of 38 virulent and temperate bacteriophages of Streptococcus lactis.

Thirty-three virulent and five temperate phages of Streptococcus lactis and Streptococcus cremoris were differentiated into three groups by DNA homology. A complete lack of DNA homology was demonstrated between the phage groups. Within each group, large parts of the phage genomes were homologous except for a few phages. One group consisted of five temperate and two virulent phages suggesting that virulent phages isolated during abnormal fermentations and temperate phages isolated after induction from lactic streptococcal starter cultures may be related to one another. We observed a good correlation between the grouping of phages by DNA homology and by their protein composition since within the same DNA homology group, the protein composition of a phage exhibited some similarities with that of the other phages of the group. Therefore, the DNA homologies seemed to be located, at least, in the region coding for the structural proteins. By immunoblotting, we confirmed the relatedness between the proteins of the phages belonging to the same DNA homology group. The important host range factor in bacterium-phage interactions appeared to be an unreliable criterion in determining phage taxonomy.

Bacteriophages↗

PubMed1987

Alterations in retrograde axonal transport in streptozocin-induced diabetic rats.

Retrograde axonal transport in the sciatic nerve of rats with streptozocin-induced diabetes was studied by the [3H]N-succinimidyl propionate [( 3H]NSP) method. The accumulation of retrogradely transported labeled proteins in the dorsal root ganglia and the ventral horn of spinal cord 1 day after [3H]NSP injection was not statistically significantly different from controls in rats diabetic for 1 or 14 days at the time of [3H]NSP injection. However, accumulation of labeled proteins in the dorsal root ganglia 7 days after [3H]NSP injection was reduced by 35% and transport to the ventral horn of spinal cord 7 days after [3H]NSP injection was reduced by 70% at the same time points. Partial control of the diabetes with insulin resulted in a partial reversal of these deficits. The early occurrence of defects in retrograde transport suggests that such defects may play a role in the pathogenesis of the neuropathy.

Animals↗

PubMed1986

Changes in intra-axonal calcium distribution following nerve crush.

We used the oxalate-pyroantimonate method to demonstrate the ultrastructural distribution of calcium within rat sciatic nerve 4 h after a crush injury. In normal nerve there are discrete gradients of axoplasmic calcium precipitate with the amount of precipitate decreasing in the axoplasm beneath the Schmidt Lantermann clefts and in the paranodal regions at the node of Ranvier. Near the crush site a marked increase in endoneurial and intra-axonal calcium precipitate correlated with morphologic evidence of axonal degeneration. More distant from the crush site, both in the distal segment destined to degenerate and in the proximal segment destined to regenerate, the most prominent finding was a loss of the normal gradient of precipitate beneath the Schmidt Lantermann clefts. The calcium influx at the crush site corresponds to the known role of calcium in triggering degeneration. The alterations in the distal axon may be an early stage leading to degeneration. Alteration in calcium distribution in the proximal nerve stump may play a role in the regulation of the response to injury.

Animals↗

PubMed1986

A quantitative study of retrograde axonal transport in motor and sensory neurons.

We used 3H N-succinimidyl propionate to covalently label in vivo proteins of the rat sciatic nerve, and studied the accumulation of radioactively labeled proteins in the cell bodies of the ipsilateral dorsal root ganglion and ventral horn of spinal cord to assess retrograde axonal transport in sensory and motor neurons respectively. In each case the early accumulation of a small amount of radioactively labeled protein is followed by the later accumulation of a larger amount, which subsequently declines to lower levels. The differences between accumulation in the motor neuron and sensory neuron are discussed. Quantitative assessment of retrograde axonal transport will allow future determination of alterations in that transport after nerve injury and in toxic states, which will help elucidate the role of retrogradely transported proteins in neuronal cell biology.

Animals↗

PubMed1986

beta,beta'-Iminodipropionitrile impairs retrograde axonal transport.

beta,beta'-Iminodipropionitrile (IDPN), a neurotoxin, causes redistribution of neurofilaments in axons followed by the development of proximal axonal swellings and, in chronic intoxication, a distal decrease in axonal caliber. The latter changes are caused by a selective impairment in the slow anterograde axonal transport of neurofilament proteins. To assess the role of retrograde axonal transport in IDPN toxicity, we used [3H]N-succinimidyl propionate ([3H]NSP) to label covalently endogenous axonal proteins in sciatic nerve of the rat and measured the accumulation of radioactively labeled proteins in the cell bodies of motor and sensory neurons over time. IDPN was injected intraneurally 6 h or intraperitoneally 1 day before subepineurial injection of [3H]NSP into the sciatic nerve, and the animals were killed 1, 2, and 7 days after [3H]NSP injection. Neurotoxicity was assessed by electron microscopic observation of the nerves of similarly treated animals. Both intraneural and intraperitoneal injection of IDPN caused an acute reduction in the amount of labeled proteins transported back to the cell bodies. The early appearance of these changes suggests that alterations in retrograde transport may play a role in the production of the neuropathic changes.

Animals↗

PubMed1986

Thirteen Virulent and Temperate Bacteriophages of Lactobacillus bulgaricus and Lactobacillus lactis Belong to a Single DNA Homology Group.

Thirteen virulent phages and two temperate phages of two closely related bacterial species (Lactobacillus lactis and L. bulgaricus) were compared for their protein composition, their antigenic properties, their restriction endonuclease patterns, and their DNA homology. The immunoblotting studies and the DNA-DNA hybridizations showed that the phages could be differentiated into two groups. One group contained 2 temperate phages of L. bulgaricus and 11 virulent phages of L. lactis. Inside each group, at least two common proteins of identical sizes could be detected for each phage. These proteins were able to cross-react in immunoblotting experiments with an antiserum raised against one phage of the same group. Temperate phage DNAs showed partial homology with DNAs from some virulent phages. These homologies seem to be located on the region coding for the structural proteins since recombinant plasmids coding for one of the major phage proteins of one phage were able to hybridize with the DNAs from phages of the same group. These results suggest that temperate and virulent phages may be related to one another.

Journal Article↗

PubMed1985

Rapid retrograde transport of proteins in sensory neurons in rats.

Twenty-four hours following the injection of N-succinimidyl[2,3-3H]propionate into rat sciatic nerve, labeled protein appeared in the ipsilateral dorsal root ganglia. Autoradiography showed that the labeled proteins were found only in neuronal cell bodies. Gel electrophoresis showed a distinct pattern of rapidly retrogradely transported proteins were accumulating in the DRG cells. This is the first demonstration of the rapid retrograde transport of endogenous axonal proteins in mammalian peripheral nerve.

Animals↗

PubMed1985

Ultrastructural localization of slow retrograde axonal transport: an autoradiographic study.

We used [3H]-N-succinimidylpropionate ([3H]-N-SP) to covalently label endogenous intra-axonal proteins within the nerve in order to study their bidirectional transport. At the time of injection virtually all of the labeled proteins are found at the injection site. At later times specific patterns of labeled proteins are found within the nerve both proximal to and distal from the injection site, as a result of retrograde and anterograde axonal transport, respectively. We undertook the current study to determine the ultrastructural distribution of the [3H]-N-SP-labeled transported proteins in the nerve. One microliter of [3H]-N-SP was injected subepineurially in sciatic nerve, and 5 days later the nerves were processed either for light and electron microscopic autoradiography or for gel electrophoresis and fluorography. At the injection site the labeled proteins are predominantly myelin proteins. Distally, a pattern similar to that described for slow anterograde transport is seen. Proximal to the injection site a constellation dominated by the 68-kilodalton protein is seen. Light microscopic autoradiography shows diffuse labeling both in axons and in myelin at the injection site, with predominant axonal labeling distant from the injection site. Electron microscopic autoradiography of segments distal to the injection site show silver grains which are distributed within the axoplasm without apparent relationship to organelles. In contrast, segments proximal to the injection site show silver grains which seem closely related to membrane-bound organelles, predominantly mitochondria. These results suggest that slow retrograde transport has a unique subcellular distribution that is distinct from that of slow anterograde transport.

Animals↗

PubMed1983

New form of familial Parkinson-dementia syndrome: clinical and pathologic findings.

We studied a family in which three siblings had a syndrome characterized by parkinsonism features, mental deterioration, pyramidal signs, and abnormal eye movements beginning in the third decade. The pathology resembled that of progressive supranuclear palsy or the Parkinson-dementia complex of Guam, but these were excluded by the clinical presentation. This syndrome appears to be a new entity.

Adult↗

PubMed1982