Biomedical subjects

J J Bernstein

Publications and source records attributed to J J Bernstein.

At least 109 records · Page 6Linked to original sources

PubMed1976

Early changes in protein synthesis following spinal cord hemisection in the Cebus monkey (Cebus apella).

The short term effects of spinal cord hemisection on protein synthesis in the Cebus monkey were studied by measuring the uptake of [3H]lysine into the trichloroacetic acid (TCA) precipitable and non-precipitable fractions of spinal cord. Animals were sacrificed 3, 6, or 13 days after hemisection. Two normal animals and a 3 day sham operate were utilized as controls. All data were pooled and subjected to analysis of variance. Significant group differences were resolved by a standad t-test over pooled operative group samples and a paired t-test for left-right differences within groups. Compared to normal animals, significant increases in the mean uptake of precursor into TCA precipitable and non-precipitable fractions of spinal cord samples were noted in all postoperative groups. The observed increase in the uptake of [3H]lysine into TCA soluble and insoluble fractions at 3 days after hemisection were attributed to stress, as were increases in the activity of the TCA insoluble fractions in the sham operate. By 6 days, the increases attributed to stress in the average protein activity seemed to subside, resulting in an overall decrease in the TCA precipitalbe protein activity with an increase in TCA soluble fraction activity. Between 6 and 13 days the activity of the TCA soluble and insoluble fractions returned to the 3 day levels with a sharp increase in the activity of both fractions in the area of the hemisection. This increase was attributed to increases in neuronal, neuroglial, and infiltrating cell metabolism possibly associated with regenerative changes.

Animals↗

PubMed1976

Ventral horn synaptology in the rat.

The synaptology of the normal ventral horn of the rat was studied. Presynaptic boutons were classified as S (Spherical vesicles), F (flattened vesicles), and G (predominance of 700-1200 A granular vesicles). In addition, Cf, Cs, M, and T synaptic complexes were defined and quantitated. Synaptology was studied on alpha-motoneuron somata, alpha-motoneuron primary dendrites, peripheral dendrites and interneuron somata. In addition, organelles were quantified for the pre- and postsynaptic members of the synaptic complex. All counts were made on coded material and these data were analyzed statistically. Motoneuron somata had significantly more (P less than 0.01) F (58%) than S (33%) boutons. This was also the case for the motoneuron primary dendrite (P less than 0.01; F, 61%; S, 37%). The small dendrites had more (P less than 0.05) S (56%) than F (44%) boutons. More Cf bulbs (P less than 0.01) were found on motoneuron somata (9%) than on motoneuron primary dendrites (2%) or interneruon somata (3%). The C complex presynaptic bouton contained spherical (Cs) or flattened (Cf) synaptic vesicles which were attributed to the fixation employed. Cf bulbs were not observed on small dendrites. G bulbs were observed (less than 1%) only on small dendrites M bulbs were not observed on any postsynaptic structure. The boutons of the motoneuron primary dendrites (15% of total afferents) and peripheral dendrites (14% of total afferents) were frequently branched whereas there was significantly (P less than 0.01) less branching of boutons on motoneuron and interneuron somata. Small postsynaptic subsurface cisterns were associated with boutons of both the S and F type on all structures. In addition, these cisterns were observed in motoneuron somata (4%) and interneuron somata (2%) without an accompanying bouton. C postsynaptic organelles were observed in motoneuron somata (3%) and primary dendrites (1%) with an overlying neuroglial cell process and no presynaptic bouton. The synaptology of the rat ventral horn is comparable to that in the cat and monkey. However, M (R) and P bulbs were not observed in the rat. This could be due to the sampling method which indicated that synapses with less than 1% occurrence fall at the level of statistical resolution in quantitative electron microscopy. The presence of postsynaptic specialization usually associated with presynaptic boutons with no presynaptic component may be a reflection of the dynamics of normal bouton renewal in the rat ventral horn.

Animals↗

PubMed1975

Alterations of central nervous system protein synthesis in response to spinal cord hemisection.

This investigation explores the central nervous system protein-synthetic responses to hemisection of the spinal cord. Adult male rats hemisected at mid T2 were given intravenous injections of 14C-leucine at 0.7, 30, or 70 days postoperative. Four hours later the T1, T2, T3, and C6 segments of the spinal cord and right and left samples of somatomotor and occipital cortex were removed, weighed, and frozen. These samples were later homogenized and subjected to trichloroacetic acid (TCA) separations. Protein-synthetic activity was expressed as the ratio of the specific activity of the TCA precipitable proteins to the specific activity of the TCA free amino acid pool. In the spinal cord samples protein-synthetic activity was greater than in controls at 7 and 30 days postoperative in the T2 segment and at 30 days postoperative in the C6 and T3 segments. In the cortical samples protein-synthetic activity was greater than in controls in the right and left somatomotor cortex at 30 days postoperative, while it was less than in controls in the left somatomotor cortex at 70 days postoperative. Thus, T2 hemisection leads to initial increases and subsequent decreases in protein-synthetic activity in both spinal cord and somatomotor cortex. These results are discussed in terms of possible regenerative neural reactions occurring in the central nervous system following spinal cord injury.

Animals↗

PubMed1975

Dendrites and neuroglia following hemisection of rat spinal cord: effects of puromycin.

Within 60 to 90 days of spinal cord hemisection or hemisection, Gelfoam, water implantation in the lesion site, ventral horn neurons 0 to 5 mm proximal to the site of lesion form varicosities along the dendrite. The varicosities form on peripheral dendrites at 10 days and progressively involve the entire dendritic shaft by 60 to 90 days. Following spinal cord hemisection and Gelfoam puromycin implantation the neurons in the ventral horn are resistant to varicosity formation. Sixty days after hemisection puromycin-treated neurons form a few varicosities on occasional peripheral dendrites with no further involvement of the dendrite by 90 days postlesion. The neuroglial reaction to hemisection is not altered by puromycin treatment. The correlation of inhibition of protein synthesis and resistance to dendritic varicosity formation is discussed.

Animals↗

PubMed1974