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Biomedical subjects

A J Windebank

Publications and source records attributed to A J Windebank.

117 records · Page 7Linked to original sources
PubMed1983

Minimal pathologic expression of a mutant gene for hereditary motor and sensory neuropathy.

Transverse sections of the sural nerve of a 46-year-old woman without neuropathic symptoms or abnormalities on nerve conduction, electromyography, or computer-assisted sensory examination contained minute regions with large onion bulbs intermingled with normal-appearing myelinated fibers and surrounded by fields of normal myelinated fibers. This woman's 19-year-old daughter had long-standing hypertrophic neuropathy with diffusely distributed large onion bulbs. Computer-imaging reconstruction of myelinated fibers and teased myelinated fiber studies of fascicles containing focal regions with onion bulbs of the mother's nerve provided evidence that onion bulbs surrounded atrophic axons with short internodes and demyelination. This is the least expression for inherited neuropathy which has been reported. These findings therefore suggest that an inherited neuropathy may be minimally expressed by a pathologic alteration of only selected neurons (axons).

Adult↗
PubMed1982

Prednisone improves chronic inflammatory demyelinating polyradiculoneuropathy more than no treatment.

Of 40 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), 28 completed a controlled three-month trial of prednisone. Prednisone was shown to cause a small but significant improvement over no treatment in scored neurological disability, some measures of computer-assisted sensory detection threshold, graded muscle strength, and some attributes of nerve conduction. No subset of patients was more likely than another to be responsive to prednisone; those with a progressive course were as likely to be responsive as recurrent cases. This finding provides further justification for classifying progressive with recurrent cases as CIDP and demonstrates that prednisone treatment should not be withheld from patients with progressive disease.

Adolescent↗
PubMed1981

Kinetics of 210Pb entry into the endoneurium.

Alteration in the blood-nerve barrier may be of primary importance in the development of experimental lead neuropathy. Using quantitative track autoradiography, we have directly demonstrated that there is a 15-fold increase in the rate of 210Pb accumulation in the endoneurium 70 days after the onset of chronic intoxication. This change in rate coincides with the appearance of edema but occurs later than the previously demonstrated total endoneurial lead accumulation and later than the onset of segmental demyelination suggesting that, in addition to rate of entry, binding within and exit from this compartment are important determinant of endoneurial lead concentration.

Animals↗
PubMed1980

The endoneurial content of lead related to the onset and severity of segmental demyelination.

The endoneurial lead and water content was serially evaluated in the nerves of rats fed lead carbonate and related to the onset and severity of segmental demyelination and remyelination. Lead began to accumulate significantly in the endoneurium by 5 days, reached a maximum level (71 microgram/g dry weight) by 34 days, and then fell to the perineurial level (28 microgram/g dry weight) by 3 months. The water content of endoneurium did not become significantly increased until the 50th day. Extensive teased fiber grading of pathologic abnormalities carried out on the same animals showed that segmental demyelination began between the 20th and 35th days and worsened progressively. This provides the first evidence that high endoneurial lead concentration precedes segmental demyelination and nerve edema. It suggests that the random Schwann cell damage is more likely to be due to a direct toxic effect of lead rather than to a factor associated with edema or increased endoneurial pressure. Contrary to our expectations, lead content does not parallel water content, as would be expected if lead entry into the endoneurium were associated with an abrupt breakdown of the blood-nerve barrier. A further new finding is the decrease in endoneurial lead content at a time when edema and the pathologic lesions are progressing. This may suggest the development of lead removal mechanisms.

Animals↗
PubMed1980

Blood nerve barrier in rat and cellular mechanisms of lead-induced segmental demyelination.

Feeding of lead carbonate to rats causes widespread and reproducible segmental de- and remyelination of myelinated fibers (MFs) of peripheral nerve. Such segmental demyelination might be explained by increased permeability of endoneurial capillaries to serum containing protein-bound lead. The perineurium of control and lead nerves was impermeable to fluorescein-labeled bovine albumin (FBA) and to horseradish peroxidase (HRP). Epineurial capillaries in both conditions allowed HRP to pass freely between and, to a lesser extent, through endothelial cells. Confirming earlier work, endoneurial capillaries of control rats did not appear to allow HRP to pass between endothelial cells, but allowed some to pass by pinocytosis through endothelial cells where it was taken up by macrophages. Contrary to expectation, flooding of the endoneurium with HRP was seen in only 1 of 36 tissue blocks of lead nerves from rats fed 4% lead carbonate for 7 1/2 and 12 weeks. Abundant HRP reaction product was seen in the epineurium in more than half of these tissue blocks. HRP was not generally found in endoneurial fluid, even in lead nerves with marked edema and widespread segmental de- and remyelination. These findings are against a massive breakdown of the blood nerve barrier, so that HRP passes freely into the endoneurium between endoneurial endothelial cells. It was our impression that HRP reaction product was slightly increased in endoneurial endothelial cells and macrophages of lead nerves as compared to control nerves. These studies suggest that there may be an increased transfer of HRP through endoneurial cells in lead neuropathy. The studies do not provide additional evidence that an altered blood nerve barrier is involved in the development of segmental demyelination in lead neuropathy.

Animals↗
PubMed1980

Interstitial hyperosmolarity may cause axis cylinder shrinkage in streptozotocin diabetic nerve.

Maximal conduction velocity values of nerves of diabetic rats 20 weeks after streptozotocin intoxication were found to be intermediate between those of onset-control and those of end-control groups. The abnormality of conduction velocity of the streptozotocin group might therefore be attributed to a failure of maturation. Detailed electron microscopic morphometry of myelinated fibers (MFs) indicates that more than lack of maturation is involved. Whereas the number of lamellae and the perimeter of axis cylinders of myelinated fibers of the three study groups suggested that growth continues, cross-sectional area of the axis cylinders of the streptozotocin group was smaller than those of either control group. Scored evaluation of fiber shape and the measured index of circularity, which related perimeter and transverse axis cylinder area, also indicated that a selective shrinkage of axis cylinders had occurred. This selective alteration in size and shape of axis cylinders is identical to that described after hyperosmolar fixation. Compared with that of controls, the serum of streptozotocin rats is hyperosmolar. It would seem reasonable to attribute the axis cylinder changes to shrinkage. Whether an additional maturational effect is operative as well cannot be resolved from our data.

Animals↗