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Biomedical subjects

J J Bernstein

Publications and source records attributed to J J Bernstein.

At least 73 records · Page 4Linked to original sources
PubMed1984

Ultrastructure of fetal spinal cord and cortex implants into adult rat spinal cord.

The ultrastructure of cortex and spinal cord from 11-, 12-, and 15-day-old fetuses implanted into the spinal cord of adult rats was studied over 3 months. Under deep Chloropent anesthesia, a 0.5 X 1.0-mm square of fetal cortex or a 1.0-mm segment of fetal spinal cord was implanted subpially between the left dorsal column and the dorsal horn of 70 adult rats. Implants grew toward gray matter, usually interfacing with the host at the isthmus between the horns of the spinal cord. However, implants were observed that occupied the entire left dorsal and ventral horns of the left half of the host spinal cord. Implants had concentric zones: A central zone with basal lamina lined joined channels and subjacent neuroglia; a zone of differentiating implant nervous system; a zone with basal lamina lined implant with overlying pial cells on the dorsal and lateral surfaces of the implant; a zone that interfaced with the host with overlapping neuropil on the lateral and ventral surfaces of the implant. Neuron types were typical for cortical or spinal implants. Implants survived for 3 months and reached stages of neuronal and neuroglial maturation similar to controls. Both fetal spinal cord and brain were successful as implants, had delayed differentiation, and formed complex neuropils. The zone of overlapping interface of the donor and host is an anatomical indication of physiological and functional integration.

Animals↗
PubMed1984

Spinal motoneuron dendritic alteration after spinal cord hemisection in the rat.

Alteration of spinal motoneurons can be induced by axotomy, deafferentation, or deafferentation of spinal interneurons. In our experiment, dendritic profiles of rat lamina IX motoneurons were studied 1.5 to 2.5 mm rostral to a T2, T3 (interface) hemisection [six per group of normal, 7-, 14-, 30-, 60-, and 90-day postoperative (DPO) animals]. The spinal cord was impregnated using the Golgi technique and individual dendritic segments measured from coded slides, the data were computerized, and the length, number of segments, and dendritic profile were reconstructed. These data were heteroscedastic (alpha less than 0.005) making them inappropriate for ANOVA. However, the data did show two size classes of motoneurons at 14, 30, 60, and 90 DPO. At 7 DPO, there was a reduced dendritic field. At 14 to 60 DPO, there were gigantic motoneurons that were many times larger than normal or other neurons in these operated groups. At 90 DPO a large motoneuron was present. These data show that individual motoneurons have different regenerative dendritic responses after spinal injury.

Animals↗
PubMed1984

Dendritic alteration of spinal motoneurons after ablation of somatomotor cortex.

After peripheral axotomy, mammalian spinal motoneuron dendrites have been shown to cyclically degenerate and regenerate and after spinal dorsal horn mince to initially increase in length and then atrophy with time. In our experiment the dendritic profile of rat lamina IX motoneurons in the spinal segment under the T2 vertebra was studied for 90 postoperative days after bilateral somatomotor cortex ablation. The spinal cords were impregnated by the tungstate modification of the Golgi technique. Individual lengths along dendritic segments between branching points were measured from coded slides, the data computerized, and the dendrites reconstructed by computer. Interanimal statistical comparisons were made a priori (ANOVA) and a posteriori (Neuman-Keuls). There were no statistical differences in dendritic length or in the number of dendritic segments with DPO. However, there were shifts in the internal branching of all dendrites. The lack of statistical significance between control and experimental animals in numbers of dendritic branches with shifting internal dendritic branching was evidence that the motoneuron dendrites were actively growing but internal dendritic branch losses and gains were indistinguishable and approximately equally along the dendrite. These shifts in internal dendritic branching may be due to loss of information from the descending tracts.

Animals↗
PubMed1984

Fetal CNS transplants into adult spinal cord: techniques, initial effects, and caveats.

Transplantation of 11 day gestation rat fetal cortex and spinal cord into adult rat thoracic spinal cord is feasible. However, the techniques used at present for the implantation of the fetal transplant result in host spinal gray matter necrosis. One day after implantation the transplant is in a fluid-filled cyst in the host. The transplanted fetal tissue forms spherical neuroepithelia and unorganized cellular arrays. At Day 3 after transplantation the implant has sedimented to the ventral aspects of the fluid-filled cyst. By 10 days, there is an active neuroepithium with differentiating neurons and neuroglia lining the basal portion of the cyst. The transplant then proceeds to fill the cavity formed by host phagocytosis of the debris in the fluid-filled cyst.

Animals↗
PubMed1983

Growth, differentiation, and viability of fetal rat cortical and spinal cord implants into adult rat spinal cord.

Successful transplantation of the fetal brain into adult host brain has been accomplished. These studies explore the growth, differentiation, and viability of E11, E12, and E15 rat fetal cortex and fetal spinal cord implantation into the spinal cord of adult rats (donor and host, Sprague-Dawley). Under deep Chloropent anesthesia, 70 rats had 1-mm cubes of fetal cortex inserted with pressure or by stylus injection subpially between the dorsal horn and dorsal column (left side), or implantation of whole segments of fetal spinal cord. Animals were prepared for light microscopy 14 and 21 days and 1, 2, and 3 months later. Implants by both fetal tissues had a 69% survival rate. The younger the fetal implant the higher the success of the implant (E11 greater than E15). The diameter of fetal spinal cord implants reached the diameter of control postnatal animals after 30 days. The implants not only increased in mass (up to 7-fold in some cases) but differentiated and matured (apolar, unipolar, bipolar, and multipolar) neurons were observed one to three months postimplantation. By 30 days postimplantation, fetal neurons had large, often crenated nuclei, with a large single prominent nucleolus. The most successful implants were the young E11 fetal spinal cord into the adult host spinal cord. These implants represent an initial successful transplantation of fetal spinal cord into adult spinal cord.

Animals↗
PubMed1983

Viability, growth, and maturation of fetal brain and spinal cord in the sciatic nerve of adult rat.

The feasibility for growth, maturation, and differentiation of fetal nervous system implanted into adult mammalian peripheral nervous system was studied. Thirty-five adult rats had the epineurium of the sciatic nerve crushed, perineurium minced, and fetal rat cortex or spinal cord implanted. Rats were utilized 7, 14, and 21 days, and 1, 2, 3, and 4 months later. A 1-mm cube of cortex or a 1-mm segment of spinal cord of 11-, 12-, or 15-day gestation fetuses was placed into the epineurium. Age-matched controls (7 DPI (days postimplantation) control for E15 implant was a 1-day pup, 21 days' gestation) were utilized for comparison (two per time group). Five animals had sciatic crush and perineurial mince only, and the gait and toe-spreading response were observed over 4 months. All implanted animals walked normally at 30 days. All implants were successful and survived the duration of the experiment. Cortical implants produced prominent bulges in the epineurium (21 days-4 months). Maximal neuronal and neurolgial cell division was observed at 7-21 days, decreased at 30 days, and stopped by 60 days. Most implanted cortical neurons had mature nuclei and immature dendritic patterns (apolar), and rarely had mature dendritic patterns. Neuroglia were abundant. The younger the cortical implant, the larger the cell mass produced (E11 greater than E15). The spinal cord implants survived, were viable, contained mainly neuroglia, and grew minimally. Host Schwann cells and nerve fibers were found in and around the implants. These data show that adult peripheral nervous system can act as an environment for growth and viability of fetal CNS implants.

Animals↗
PubMed1983

Dendritic alteration of rat spinal motoneurons after dorsal horn mince: computer reconstruction of dendritic fields.

Mammalian spinal motoneuron dendrites respond with cyclic degeneration and regeneration after ventral root crush. In the following experiments, the cross-sectional dendritic profile of rat lamina IX, medial, motoneurons under the T2 vertebra were analyzed after mincing the dorsal horn (normals, 14, 30, 60, 90 days postoperative (DPO); N = 6 animals/DPO). The spinal cords were impregnated by the tungstate modification of the Golgi technique. Individual lengths along dendritic segments between branching points were measured from coded slides, the data were computerized, and the dendrites were reconstructed by computer. Interanimal statistical comparisons were made by ANOVA a priori and Newman-Keuls test a posteriori. At 14 DPO, there was a statistically significant (P less than 0.05) increase in the number of dendritic segments, dendritic and serpentine length, and number of segments emanating from the soma compared with normal intact rats and with all other postoperative days. At 30 and 60 DPO, these parameters returned to normal values; however, there were many long, unbranched dendrites. At 90 DPO, there was a statistically significant (P less than 0.05) decrease in motoneuron dendritic serpentine length and segments. These data show that partially deafferented rat spinal motoneurons undergo a biphasic response; an initial growth phase followed by a degenerative phase.

Animals↗
PubMed1983

[3H]lysine incorporation into protein of hemisected, cycloheximide-treated spinal cord.

A single application of a protein synthesis inhibitor, puromycin, in the lesion site of a spinal hemisection transiently decreases protein incorporation for less than 24 h and results in axonal sprouting and dendritic and synaptic stability for at least 60 days. In this study we characterized the protein-altering properties of single applications of a different protein synthesis inhibitor, cycloheximide, for comparison. The protein incorporation of [3H] lysine into hemisected rat spinal cord (left side, T2) treated with cycloheximide (100 micrograms/ml in Gelfoam sponge placed in wound at time of lesion) was tested 3 h, 6 h, 12 h, 1, 3, 7, and 14 days later and compared with that in 0.9% saline in Gelfoam implants as normal controls (N = 54). One hour prior to utilization, the animals were injected subcutaneously with 200 mu Ci L-[4,5(n)-3H]lysine monohydrochloride. No treatment-related differences in brain radioactivity were noted at any time postoperation. In spinal cord, inhibition of amino acid uptake by cycloheximide was not demonstrable at 3 h after hemisection, but could be detected from 6 h to 1 day after implantation. During that time, the TCA-soluble radioactivity at the lesion site was greater than in control animals (P less than 0.05). These results suggest that as with puromycin, morphologic effects produced by cycloheximide on spinal cord regeneration may correspond to chemical events which occurred within the first 24 h after cord hemisection and cycloheximide treatment.

Animals↗
PubMed1982

Sonication-enhanced histochemistry of wheat germ agglutinin binding to intracellular sites of rat layer V cortical neurons and spinal motoneurons.

Cellular surface carbohydrates have been studied extensively in relation to cell interactions. However, the presence of intracellular carbohydrates not associated with cell surface membranes has not been well-defined histochemically. We describe a technique for the ultrastructural localization of intracytoplasmic carbohydrates using a wheat germ agglutinin peroxidase conjugate. The ultrastructural aspects of wheat germ agglutinin (WGA) binding to intracellular structures of rat somatomotor cortex layer V neurons and spinal cord motoneurons were examined using sonication to enhance penetration of the lectin-peroxidase conjugate. In addition to the membrane-associated structures previously described by others, WGA binding was observed on neuronal nuclear chromatin, nuclear pores, ribosomes, microtubules, vesicular organelles, and to synaptic complexes, primarily in the presynaptic bouton. The results support data indicating that complex carbohydrates may be important in neuronal molecular processing.

Animals↗
PubMed1982

Long-term axonal apposition in rat sciatic nerve neuroma.

Long-term electrophysiological cross-talk between nerve fibers has been demonstrated in rat sciatic nerve following induction of an amputation neuroma. Experiments wee designed to establish an anatomical basis for this phenomenon. The sciatic nerve was transected and the epineurium oversewn with 10-0 nylon in 16 adult male Sprague-Dawley rats. The resulting neuromas were prepared for ultrastructural analysis 7, 14, 30, and 60 days later. An analysis of the unmyelinated nerve fibers showed normal configuration of the fibers, with normal organelles, separated by Schwann cell processes in the neuroma. However, degenerating unmyelinated nerve fibers and nerve fibers with masses of neurofilaments were often observed. In approximately 10% of the total population observed, there were two or more unmyelinated nerve fibers in a single Schwann process fascicle. Some of the multiple unmyelinated nerve fiber fascicles had nerve fibers that were in membranous apposition. This configuration of unmyelinated axons could form the anatomical basis for long-term physiological cross-talk between axons in a neuroma, and could be of consequence in pain production.

Animals↗
PubMed1981

Projections of caudal fasciculus gracilis to nucleus gracilis and other medullary structures, and Clarke's nucleus in the rat.

The extent of the projection of fasciculus gracilis from low thoracic (T12--13) spinal cord, to nucleus gracilis (NG) was studied by the Nauta--Gygax method in the rat in order to: (1) help define projection fields of fasciculus gracilis hindlimb and tail afferents along the longitudinal extent of NG; and (2) broaden the comparative data on the projection of the lower body to NG via fasciculus gracilis, already known in cat and monkey. Results showed that: (1) degenerated fasciculus gracilis axons are situated mainly dorsal to the corticospinal fibers, in the dorsal funiculus; (2) terminal projection fields were located at all levels of ipsilateral NG--caudal to the obex, terminal debris was confined to the medial two-thirds of NG--rostrad of the obex, in oral NG, degeneration was of finer caliber and projection fields more diffuse; and (3) ipsilateral degeneration was also seen at the level of a portion of Clarke's nucleus, and, in commissural and lateral cuneate nuclei and medial reticular formation in medulla.

Afferent Pathways↗
PubMed1981

Bouton renewal patterns in rat hindlimb cortex after thoracic dorsal funicular lesions.

The transneuronal effect of bilateral, dorsal funicular lesions (T 12) on the frequency of boutons on cells in layer IV of hindlimb cortex was studied. Adult rats were utilized 1, 2, 3, 7, 14, 30, 45, 60, 90, or 120 days postoperative (DPO), and tissue was processed for the light microscopic visualization of silver-impregnated boutons (Rasmussen method). Bouton counts were taken on soma, or along 5- and 10-micrometers segments or proximal dendrite branching from soma. The soma diameter also was measured on those neurons chosen for bouton counts on the circumference of the soma. Statistically significant, increased afferentation on soma and proximal dendrite occurred during the first postlesion week relative to longer survival times; bouton counts on the proximal dendrite showed a trend (not statistically significant) toward increases above normal. These data mirror similar, consistent increases in bouton counts reported in thalamic ventroposterolateral nucleus of these same cases. At 14 DPO, bouton counts on the soma decreased below normal (P less than 0.005) and, except at 60 DPO, remained so through 120 DPO (P less than 0.025). Bouton counts on the proximal dendrite also decreased below normal at 14 DPO (P less than 0.005), thereafter exhibiting either periodic (along 5-micrometers) or extended (along 10-micrometers) periods in significant decreases from normal. Correlations in lesioned cases between the number of boutons on the soma and either bouton counts on proximal dendrite or soma diameter were positive and statistically significant (P less than 0.005 in all correlations). Possible anterograde (via the dorsal column-medial lemniscal system) and/or retrograde (via the corticospinal tract) transneuronal mediation of these effects in hindlimb cortex is discussed.

Animals↗
PubMed1981

Influence of triiodothyronine on the amino acid uptake of brain and spinal cord in normal and spinal hemisected adult rats.

The thyroid hormones triiodothyronine (T3) and L-thyroxine appear to enhance regeneration in the peripheral and central nervous system (CNS). The following experiments examine possible metabolic substrates for the action of T3 on the adult rat CNS after spinal hemisection. The protein incorporation of (3H)lysine after a left spinal hemisection (T2) or control operations was examined 1, 3, 7, and 14 days postoperation. Triiodothyronine (1 microgram/kg body weight in a bicarbonate buffer) was injected daily for the postoperation or equivalent time period. One hour prior to decapitation, animals were given a subcutaneous injection of 200 microCi of (3H)lysine. Samples of brain and spinal cord were dissolved, and the radioactivity of acid-precipitable protein and acid-soluble fractions were determined by scintillation counting. T3 treatment influenced the general levels of incorporation of all treated groups over all days postoperation. Specific effects were observed in spinal hemisected T3-treated animals. A significant hemispheric (P less than 0.05) asymmetry was present at 3 days postoperation with the right somatomotor cortex higher in protein radioactivity than the left. In spinal cord, the area of the lesion and areas just caudal to the lesion were higher in (3H)lysine incorporation in T3-treated rats relative to controls. T3 effects appear to involve an increased sensitivity of the cells of the injured nervous system to the hormone.

Amino Acids↗