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M Vitadello

Publications and source records attributed to M Vitadello.

32 records · Page 2Linked to original sources
PubMed1988

The synaptic vesicle proteins synapsin I and synaptophysin (protein P38) are concentrated both in efferent and afferent nerve endings of the skeletal muscle.

Synapsin I and synaptophysin (protein p38) are 2 major protein components of the membranes of small synaptic vesicles of virtually all presynaptic nerve endings. Synapsin I, a phosphoprotein regulated by both Ca2+ and cAMP, is a peripheral protein of the cytoplasmic surface of the vesicle membrane. It is thought to anchor the vesicle surface to the cytoskeleton of the terminal and to play a regulatory role in neurotransmitter release. Synaptophysin is an intrinsic transmembrane glycoprotein. We report here that both proteins are present and concentrated also in afferent nerve endings, which provide the sensory innervation of the skeletal muscle and of the tendon. The distribution of both antigens in sensory nerve endings is consistent with their localization on the microvesicles that have been described in such endings. Thus, our results suggest the existence of important biochemical, and possibly functional, similarities between small synaptic vesicles of presynaptic nerve endings and microvesicles of sensory endings. Such findings provide new clues to the understanding of the physiology of sensory endings.

Afferent Pathways↗
PubMed1987

A developmentally regulated isoform of 150,000 molecular weight neurofilament protein specifically expressed in autonomic and small sensory neurons.

Neurofilament heterogeneity has been demonstrated using a monoclonal antibody (CH1) specific for the 150,000 molecular weight neurofilament subunit. In the peripheral nervous system of adult rats CH1 stained selectively sympathetic and parasympathetic neurons and a subpopulation of small neurons in the sensory dorsal root ganglia. Somatic motor neurons and large neurons in dorsal root ganglia were completely unreactive. In contrast, the anti-neurofilament antibody iC8, directed against the 150,000 molecular weight subunit, labelled all peripheral nervous system neurons. The immunostaining pattern with both antibodies was unchanged by phosphatase treatment. These data indicate that two antigenically distinct variants of the 150,000 molecular weight neurofilament subunit exist in somatic and autonomic neurons of adult animals. In addition, the phosphatase treatment suggests that the antigen recognized by CH1 is not masked by phosphorylation. In contrast, all neurons were labelled by this antibody in the peripheral nervous system of newborn rats. It is suggested that CH1 identifies a fetal 150,000 molecular weight neurofilament polypeptide isoform whose expression is prevented by the growth of somatic neurons and is selectively maintained in autonomic and small sensory neurons.

Adrenergic Fibers↗
PubMed1986

Impaired axonal transport of acetylcholinesterase in the sciatic nerve of alloxan-diabetic rats: effect of ganglioside treatment.

The anterograde and retrograde axonal flow of acetylcholinesterase were studied in the sciatic nerve of alloxan-diabetic rats after five weeks of experimental diabetes. A slight reduction of the anterograde axonal flow of the enzyme was found in alloxan-diabetic compared to control rats. Sedimentation analysis revealed a major reduction of anterograde axonal flow of the light globular forms of the enzyme (G1 + G2), which are probably conveyed by slow transport. There was also a minor reduction of the anterograde flow of the globular form G4, while no modification of the axonal flow of the heavy asymmetric form A12 was found. Both G4 and A12 molecular forms are conveyed by fast axonal transport. In contrast, no abnormality of the retrograde axonal flow of acetylcholinesterase was observed. Ganglioside treatment antagonized the decline of the anterograde axonal flow of the enzyme in alloxan-diabetic rats. These results are consistent with the view that experimental diabetic neuropathy is associated with axonal transport defects, and suggest a protective effect of ganglioside treatment against neuronal damage(s) related to the diabetic syndrome.

Acetylcholinesterase↗
PubMed1986

Heterogeneity of rat neurofilament polypeptides revealed by a monoclonal antibody.

A monoclonal antibody obtained from mice immunized with a crude neurofilament preparation from newborn rat brain revealed the existence of heterogeneity of the 200,000- and 150,000-dalton neurofilament polypeptides. On immunoblot the monoclonal antibody iC8 reacted with both the 200,000- and 150,000-dalton components in the CNS, but only with the 150,000-dalton polypeptide in sciatic nerve preparations. In addition, the 150,000-dalton polypeptide appeared as a single band in the sciatic nerve, whereas in the CNS a doublet was labeled by iC8. In contrast a second monoclonal antibody (3H5) reacted with the 200,000-dalton peptide and a single 150,000-dalton component in both the central and peripheral nervous system preparations. The differences revealed by iC8 were probably not due to phosphorylation, as the pattern of antibody binding in immunoblots was not changed by pretreatment with alkaline phosphatase. The findings suggest that different isoforms of neurofilament polypeptides are present in the nervous system.

Animals↗
PubMed1985

Altered axonal transport of cytoskeletal proteins in the mutant diabetic mouse.

Polypeptides in the motor axons of the sciatic nerve in 120-day-old normal and diabetic mice C57BL/Ks (db/db) were labeled by injection of [35S]methionine into the ventral horn of the spinal cord. At 8, 15, and 25 days after the injection, the distribution of radiolabeled polypeptides along the sciatic nerve was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four major radiolabeled polypeptides, tentatively identified as actin, tubulin, and the two lightest subunits of the neurofilament triplet, were studied in both diabetic and control mice. In the diabetic animals, the two polypeptides identified as actin and tubulin showed a reduction of average velocity of migration along the sciatic nerve, resulting in a higher fraction of radioactivity in the proximal part of the sciatic nerve, whereas the front of radioactivity (advancing at maximal velocity) moved at a normal rate. In contrast, both the average and maximal velocities of the two neurofilament subunits were slower in the diabetic mice than in the control mice. These results indicate that the axonal transport of the cytoskeletal proteins is differentially affected in the course of diabetic neuropathy, and may suggest that the impairment concerns mainly the proteins carried by the slowest component of axonal transport.

Actins↗
PubMed1984

Ganglioside treatment of genetic and alloxan-induced diabetic neuropathy.

Peripheral neuropathy is a common complication of diabetes. Using the mutant diabetic mouse C57BL/ks (db/db) and alloxan-treated rats, 30 days after intoxication, we investigated development and treatment with gangliosides of such a disease. The db/db mouse develops a neuropathy characterized by a loss in conduction velocity shown as early as 80-90 days after birth and maintained throughout life. At later stages (5-6 months of age) there is a drop in slow transport and myelin particle density. These changes are correlated by a lack of response to insulin treatment, which, prior to this stage, is capable of improving nerve conduction velocity (NCV). On the other hand gangliosides became effective, improving NCV, myelin particle density and sensory perception (auditory deficit) at 5 months of age in the db/db mouse. We presume that this differential neuronal response to insulin and gangliosides indicates a change of the neuropathy from a metabolic stage to neuronal. Alloxan induced diabetic neuropathy is treatable with gangliosides even 30 days after intoxication.

Acetylcholinesterase↗
PubMed1983

Axonal transport of acetylcholinesterase in the diabetic mutant mouse.

During the development of diabetic neuropathy in the mouse C57BL/Ks (db/db), the axonal transport of AChE molecular forms was tested in the sciatic nerve, by measuring the accumulation of enzyme activity in front of a nerve transection. No alteration of the fast flow rate of G4 and A12 molecular forms was found until 220 days of age. On the other hand, a reduced flow rate of G1 and G2 molecular forms, probably conveyed by slow axoplasmic flow, was noticed in the late phase of diabetic neuropathy. This result is consistent with the view that axonal dwindling could be related to disturbances of slow axonal transport and that the reduction in conduction velocity, observed at an earlier stage, may be due to other causes.

Acetylcholinesterase↗
PubMed1982

Myosin isoenzymes in cultured human muscle.

Cultured human muscle grown aneurally and innervated by the ventral part of fetal rat spinal cord was examined using antimyosin antibodies specific for isomyosins from fast and slow mammalian skeletal muscle. Cultured muscle displayed multiple reactivity with antibodies against both types of myosins, with no evident compartmentalization of different forms of myosin into different muscle cells, such as seen in adult muscle. Innervation of cultured muscle resulted in better growth and longer survival of cultured muscle and its more advanced maturation, with a larger number of cross-striated muscle fibers. The pattern of immunofluorescence reaction, however, was the same in both innervated and noninnervated cultured muscle.

Antibodies↗
PubMed1981

"Fast" isomyosins and fiber types in mammalian skeletal muscle.

Immunohistochemical procedures have been used to correlate antigenic differences among fast isomyosins with their specific localization in particular types of rat muscle fibers. Antisera were produced in rabbits against myosins isolated from guinea pig fast-white (tensor fasciae latae) and fast-red (masseter) muscles. After sequential cross-adsorptions on insolubilized heterologous myosins, antibodies mainly directed against heavy chain determinants were obtained. In indirect immunofluorescence assays, these antibodies selectively stained fast-white (type IIB) and fast-red (type IIA) fibers, respectively. Slow-twitch (type I) fibers, which were reactive with antibodies against soleus muscle myosin, were unreactive with anti-fast-myocin antibodies. In addition to these major types of fibers, with unique immunoreactivity, two groups of fibers with double reactivity were identified: 1) fibers reactive with anti-slow-twitch and anti-fast-red antibodies (corresponding to IIC fibers with enzyme histochemistry) and 2) fibers reactive with anti-fast-red and anti-fast-white antibodies. We propose to identify these fibers with the symbols I in equilibrium with IIA and IIA in equilibrium with IIB, respectively, as they may be considered as intermediate and/or transitional stages between the major fiber types. No fibers were reactive with both anti-slow-twitch and anti-fast-white antibodies. Therefore, muscle fibers may change in a sequential manner, from I leads to IIA leads to IIB or in the reverse direction, suggesting an obligatory sequence of gene activation.

Animals↗
PubMed1980

"Slow" myosins in vertebrate skeletal muscle. An immunofluorescence study.

Specific antisera were raised in rabbits against column-purified myosins from a slow avian muscle, the chicken anterior latissimus dorsi (ALD), and a slow-twitch mammalian muscle, the guinea pig soleus (SOL). The antisera were labeled with fluorescein and applied to sections of muscles from various vertebrae species. Two distinct categories of the slow fibers were identified on the basis of their differential reactivity with the two antisera. Fibers stained by anti-ALD appear to correspond in distribution and histochemical properties to physiologically slow-tonic fibers, i.e., fibers that display multiple innervation and respond to stimulation with prolonged contractures. In mammals, only a minority of fibers in extraocular muscles and the nuclear bag fibers of muscle spindles were brightly labeled by this antiserum. In contrast, fibers labeled by anti-SOL in mammalian muscle appear to correspond in distribution and histochemical properties to physiologically slow-twitch fibers. Anti-SOL was also found to stain a population of fibers in reptiles, amphibians, and fishes that did not react, or reacted poorly, with anti-ALD; in avian muscle, only a minor proportion of the slow fibers were labeled by anti-Sol. these findings point to the existence of two antigenically distinct, though partly cross-reacting, types of "slow" myosin in vertebrate muscle.

Amphibians↗
PubMed1979

Development of the sarcotubular system in fusion-arrested myoblasts.

We have compared the effect of two different procedures, equally effective in preventing muscle cell fusion in culture, on the development of the sarcotubular system in rat muscle cells. Whereas in myoblasts grown in low Ca++ medium the T system was poorly developed and diadic or triadic couplings between T tubules and sarcoplasmic reticulum were rare, in cytochalasin B-treated myoblasts the development of the sarcotubular system was comparable to that seen in myotubes of the same age. We conclude that (a) muscle cell fusion is not essential for the development of the sarcotubular system, and (b) procedures used to prevent cell fusion in vitro may affect directly muscle cell differentiation by a process independent of the fusion block.

Animals↗
PubMedDate not supplied

Complementary immunohistochemical distribution of the neurofilament triplet and novel intermediate filament proteins in the autonomic and sensory nervous system of the guinea-pig.

We have previously established that immunoreactivity for the triplet of polypeptides that comprise the class IV intermediate filament proteins (NFP-triplet) is localized in specific subpopulations of neurons in guinea-pig sensory and autonomic ganglia. Antibodies to novel neurofilament proteins, including a polyclonal antibody to a 57 kDa neuronal intermediate filament polypeptide (NIF57kD) and a monoclonal antibody (CH1) to a 150 kDa intermediate filament, or associated, protein were used in combination with antibodies to the NFP-triplet for double-labelling immunohistochemistry. The results show that different subpopulations of neurons in the guinea-pig dorsal root ganglia, coeliac ganglion and enteric ganglia can be distinguished by their complementary immunoreactivity for these proteins. In dorsal root ganglia, larger neurons are intensely immunoreactive for the NFP-triplet while immunoreactivity with CH1 and NIF57kD antibodies is restricted to the small to medium-sized neurons. In the coeliac ganglion, two regionally defined subpopulations of neurons can be distinguished by their immunoreactivity for either the NFP-triplet or NIF57kD, whereas CH1 labels all neurons with equal intensity. Three classes of morphologically distinct myenteric neuron subpopulations are also distinguished by their immunoreactivity for either the NFP-triplet, NIF57kD or CH1 antibodies. Two classes of submucous neurons are labelled both with CH1 and NIF57kD antibodies but show faint or no immunoreactivity for the NFP-triplet. It is concluded that intermediate filament protein immunoreactivity marks different subpopulations of neurons, which suggests that these proteins may have specific roles in neuronal function.

Animals↗