Relative carnitine insufficiency in children with type I diabetes mellitus.

Recognizing the similarity of type I diabetes mellitus to inborn errors of metabolism that have responded to carnitine therapy, we initiated a study of 54 children with type I diabetes mellitus. Examining a fasting blood sample for levels of carnitine, glucose, and glycosylated hemoglobin A1c, and a urine sample for levels of ketones and glucose, we found 13 children were deficient of free carnitine (less than 20 mumol/L) and 30 had elevated acyl carnitine levels (greater than 11 mumol/L). Statistical tests confirmed a significant difference between the diabetic population and normal population for reduced free carnitine, elevated acyl carnitine, and an elevated ratio of acyl carnitine to free carnitine. Also, a significant correlation was found between the levels of urine glucose and ketones and the level of acyl carnitine. Our data indicate that carnitine deficiency and relative insufficiency may be an overlooked component in the management of diabetes.

Effects of antidromic stimulation of the ventral root on glucose utilization in the ventral horn of the spinal cord in the rat.

Electrical stimulation of the proximal stump of the transected sciatic nerve increased glucose utilization in the ventral horn of the spinal cord, with the greater increase in Rexed's lamina IX. Antidromic stimulation of the ventral root, however, did not change glucose utilization in the ventral horn. These results suggest that the axon terminals and not the cell bodies are the sites of enhanced metabolic activity during increased electrical activity in these elements.

Spinal origins of cardiac afferents from the region of the left anterior descending artery.

The origins of coronary artery afferents coursing in sympathetic nerves was determined using retrograde axonal transport methods. Cells labeled with horseradish peroxidase were found bilaterally in dorsal root ganglia (DRG) C8 to T6 were smaller in size than non-labeled DRG neurons. The findings indicate a more extensive segmental distribution of cardiac afferents than was previously believed to exist.

Segmental localization of sensory cells that innervate the bladder.

The present study labels the neuronal cell bodies that give rise to afferent fibers that innervate the bladder of cat and rat. The method used was the retrograde transport of horseradish peroxidase (HRP) from its injection site in the bladder to cells in various dorsal root ganglia. In the rat, the labelled cells are located in the L1-L2 and L6-S1 dorsal root ganglia. In the cat, the labelled cells are located in the L2-L5 and S1-S4 dorsal root ganglia. This confirms older clinical findings, and for the first time directly demonstrates the afferent cell bodies for the bladder. The bladder afferents are small ganglion cells in both rat and cat, and because there is a correlation between the size of axon and the cell body from which it originates, we conclude that the great majority of bladder afferents are small myelinated or unmyelinated axons. In addition, by restricting the HRP to one side of the bladder, we are able to show that some afferent cell bodies send their distal processes across the midline. These results will be useful in considerations of the neural control of bladder function.

Unmyelinated fibres in the sacral 3 and caudal 1 ventral roots of the cat.

1. 29% of the axons in the S3 and Ca 1 caudal ventral roots of the cat are unmyelinated. 2. Approximately one half of these unmyelinated axons survive in the proximal stump of a sectioned ventral root and are regarded as unmyelinated preganglionic efferents. 3. At least 27% of the preganglionic efferents in segments S3 and Ca 1 are unmyelinated. 4. The other half of the ventral root unmyelinated axons arise from dorsal root ganglion cells and survive in the distal stump of a sectioned ventral root. 5. The data in 4, combined with the receptive field data in our companion paper, show that these unmyelinated fibres are sensory. 6. Since 15% of the ventral root axons are sensory, the Law of Bell and Magendie cannot be regarded as an accurate description of the organization of these ventral roots.

Receptive fields of unmyelinated ventral root afferent fibres in the cat.

1. The receptive fields were determined for 118 afferent fibres in the S2, S3 and Ca (caudal) 1 ventral roots of the cat. Of these fibres, ninety-three were unmyelinated, another eleven were probably unmyelinated, and fourteen were myelinated, according to estimates of their conduction velocities. 2. Confirmation that the recordings were from ventral root filaments came from electron microscopic inspection of ten of the filaments from which recordings of the activity of unmyelinated afferents were made. 3. Receptive fields were demonstrated for twelve unmyelinated afferent fibres in the distal stumps of the S2 and S3 ventral roots which had been sectioned 3 weeks previously, indicating that the cell bodies giving rise to these fibres were not in the spinal cord. 4. The action potentials of some of the unmyelinated ventral root afferent fibres were complex, suggesting branching of the afferents within the ventral root. 5. One third of the unmyelinated ventral root afferents had receptive fields in somatic structures: the skin and deep tissues. 6. Two thirds of the unmyelinated ventral root afferents had receptive fields in the viscera of the pelvis: the bladder, urethra, vagina, and lower bowel. 7. Many of the unmyelinated afferents in the ventral roots, especially those with cutaneous receptive fields, had high thresholds and may participate in nociception. 8. It is concluded that the cat ventral root contains a major sensory component and that the Law of Bell and Magendie is not an accurate description of the organization of the ventral root in this animal.

Unmyelinated preganglionic fibers in frog ventral roots.

It has been suggested that the preganglionic visceral fibers in the frog are unmyelinated. To obtain further evidence for this suggestion: (1) the percentages of unmyelinated fibers and the myelinated fiber histograms were done for all frog ventral roots, (2) the number of unmyelinated fibers were counted on either side of a chronic section of the seventh ventral root and (3) compound action potentials were obtained for roots 7-10. The results are that slightly more than 80% of the unmyelinated fibers in the seventh ventral root arise in the spinal cord and are presumably unmyelinated preganglionic efferents. Furthermore, a C fiber volley could be followed from the seventh ventral root into caudal parts of the sympathetic chain. Thus this data provides confirmation for the idea that many frog preganglionic fibers are unmyelinated. This study also shows that 24% of the ventral root axons in the frog are unmyelinated and that, on the basis of percentages of unmyelinated fibers and myelinated fiber histograms, there are five categories of frog ventral roots.