Inhibiting effect of minocycline on the regeneration of peripheral nerves

The effect of minocycline on nerve regeneration was studied in a rat model of acute sciatic nerve injury, in which the injury was caused by resection and reimplantation of the right sciatic nerve. Immunohistochemical and molecular biological methods, as well as morphometric and electron microscopic techniques, were used. Compared with uninjured and PBS-treated injured nerves, the minocycline-treated injured nerve showed: (i) a decrease in macrophage recruitment and activation, probably resulting from inhibition of blood-brain-barrier break-down via reduced MMP2 and MMP9 induction, inhibition of revascularization via additional reduction of VEGF induction, and inhibition of inducible NO synthase (iNOS) induction; (ii) reduced activation of phagocytic Schwann cells, probably by inhibition of iNOS, MMP2 and MMP9 expression; (iii) a slowed Wallerian degeneration; and subsequently, (iv) a diminished nerve regeneration. Macrophages, especially their function in the removal of cellular debris and formation of a microenvironment beneficial for nerve regeneration, are strongly implicated in constructive events after nerve injuries. Therefore, we suggest that additional research into optimizing minocycline intervention for treatment of neurodegenerative diseases is needed before further clinical trials are performed.     

Results of decompression of peripheral nerves in diabetics: a prospective, blinded study

Diabetic neuropathy traditionally is considered progressive and irreversible and will result in lower extremity ulceration and amputation in a segment of the diabetic population, despite the best efforts to control serum glucose levels. Restoration of sensation to the diabetic may prevent these complications of neuropathy. The present study was designed to evaluate whether decompression of a peripheral nerve at a known site of anatomic narrowing can restore sensibility to that nerve in the diabetic. Twenty diabetic patients ( 14 type I, 6 type II, with a mean duration of diabetes of 14.8 years) had surgical decompression of a median nerve at the wrist and an ulnar nerve at the elbow, or a decompression of the posterior tibial nerve at the ankle (total of 31 nerves). A therapist, in a manner blind to the operative site, evaluated two-point discrimination in the pulp of the appropriate digit. The postoperative sensibility was compared with that of the nontreated, contralateral extremity. At a mean of 23.3 months, 69 percent of the lower-extremity nerves and 88 percent of the upper-extremity nerves (79 percent overall) had improvement in sensibility. In comparison, 32 percent of the control (not decompressed) contralateral nerves had measurable progression of neuropathy. The hypothesis that decompression of a peripheral nerve in the diabetic will improve sensibility was confirmed at the p < 0.001 level.     

Distant migration of silicone gel from a ruptured breast implant. Case report.

A complication of augmentation mammaplasty is presented in which the bag of a gel-filled implant ruptured and the thin gel migrated through subcutaneous planes as far as the groin. We feel that when a rupture of a gel-filled prosthesis becomes evident, it should be replaced as soon as possible if such migration is to be prevented (particularly if the gel is of the thinner and less-cohesive variety).     

Electron microscope study on the regenerative process of peripheral nerves of mice

Summary An electron microscope study of the reactive process taking place in the proximal segment of sectioned dorso-spinal nerves of white mice was carried out in about 50 animals. Attention was mainly directed to the study of the earliest changes (30) observable in the neuroplasm but the series of experiments included the study of nerves fixed up to 20 days after section.Most of the facts found (existence of microvesicles, multiplication of mitochondria, and presence of multivesicular bodies) confirmed the observation done in a preceding investigation, plus some non-described new findings.Early after section (30) the nerve membrane is seen, in some cases, masked by the presence of microvesicles which seem to take origine from the membrane which also shows deep infoldings. These coalesce in many places taking thus the appearance of rows of vesicles.At later stages (60, 80) this reactive process is more general in the nerve stumps and vast areas of microvesicles are seen in the fiber neuroplasm. This kind of reaction (membrane infolding and coalescence) decrease later on and is rarely observable at 100. Microvesicles are nevertheless increasing in number and many of them change their round profile for an elongated shape. Elongation leads to the formation of tubuli of progressively thinner diameter. This process is described as a possible way of neurofilament formation.This research was supported by the United States Air Force under Contract No AF 49 (638) 585 and Grant AF 61–64, monitored by the Air Force Office of Scientific Research, Air Force Research Division of the Air Research and Development Command.     

Insect peripheral nerves: accessibility of neurohaemal regions to lanthanum.

During incubation in vivo, exogenously applied ionic lanthanum comes to surround the numerous neurosecretory terminals which are found lying within or immediately beneath the acellular neural lamella ensheathing the nerves from fifth instar and adult specimens of Rhodnius prolixus. The lanthanum does not penetrate beyond the cellular perineurium, which completely surrounds the non-neurosecretory axons in these nerves and constitutes a form of 'blood-brain barrier'. In some cases, however, lanthanum is found in the vicinity of a neurosecretory axon lying beneath the perineurium, where it can be assumed to have leaked in from the neurosecretory terminal lying free in the neural lamella. When nerves are incubated in calcium-free media, regions with an attenuated perineurium become 'leaky', in that lanthanum is found lying in those extracellular spaces between axons and glia which lie immediately below the thin part of the perineurial layer. Bathing solutions made slightly hyperosmotic to the haemolymph with sucrose have no apparent disruptive effects on the barrier. When the tissues are incubated in more hypertonic solutions, the perineurial barrier becomes 'leaky' throughout, and tracer pervades beyond its cells into all the intercellular spaced between glia and axons. The possible role of the zonulae occludentes in both the maintenance of the perineurial barrier and in the formation of interglial occlusions to local penetration of exogenous substances is considered.     

Hypertrophic sternal scars: silicone gel sheet versus Kenalog injection treatment.

A prospective, randomized trial was designed to compare the standard Kenalog injection of established hypertrophic sternal scars with topical silicone gel sheets (Spenco). Fourteen poststernotomy cardiac patients with symptomatic scars were randomized to treatment in one-half of the scar with Kenalog injection. Simultaneously, the other half of the scar received the silicone gel sheet. The standard Kenalog injection used was 40 mg/ml x 1 cc, mixed with 1 cc of 1% Xylocaine with epinephrine. The gel sheets were worn continuously for 12 hours for 12 weeks. Pretreatment and posttreatment photographs were compared for color and appearance by blindfolded observers. Scar measurements (length, width, and height) were taken weekly in each area, and the patients were asked to rank their symptoms within each half as worse, the same, or better. The primary outcome of patient preference was analyzed sequentially, and the recruitment was terminated after 11 patients had completed the study, 10 of whom favored the silicone gel treatment (p < 0.05). Three patients remained in the treatment phase at the time of termination and completed the study subsequently. For the total sample of 14 subjects, 11 preferred the silicone gel, 1 expressed no preference, and 2 preferred the injection. The average time to improvement was 3.9 +/- 0.62 days (gel) versus 6.8 +/- 1.86 days (Kenalog). This study demonstrates that silicone gel sheets provide earlier symptomatic relief and a more aesthetic scar and are the preferred treatment of patients with symptomatic hypertrophic sternal scars.     

Variability in the properties of silicone gel breast implants.

Several generations of silicone gel breast implants have been produced by implant manufacturers. The primary material usually viewed as the base material in the manufacture of implants is polydimethylsiloxane. Polymeric reactions are notorious for their variability and nonuniformity. The elastomer used in different types of implants can have vastly different properties. Furthermore, the material properties associated with a particular type of implant can vary considerably from one lot to the next. Considering the various designs, styles, and manufacturing techniques associated with silicone gel implants, knowledge of the original properties of the implants before implantation is important in determining the effects of aging in vivo. This study was conducted to investigate differences in key mechanical and chemical properties of silicone gel breast implant materials. The two types of implants chosen for analysis were Silastic I and Silastic II control implants. Material property data were determined for both types of controls and significant differences were found in their values. Lot-to-lot variability was also investigated and found to be significant.