Cumulative Brain Injury from Motor Vehicle-Induced Whole-Body Vibration and Prevention by Human Apolipoprotein A-I Molecule Mimetic (4F) Peptide (an Apo A-I Mimetic).

BACKGROUND: Insidious cumulative brain injury from motor vehicle-induced whole-body vibration (MV-WBV) has not yet been studied. The objective of the present study is to validate whether whole-body vibration for long periods causes cumulative brain injury and impairment of the cerebral function. We also explored a preventive method for MV-WBV injury. METHODS: A study simulating whole-body vibration was conducted in 72 male Sprague-Dawley rats divided into 9 groups (N = 8): (1) 2-week normal control; (2) 2-week sham control (in the tube without vibration); (3) 2-week vibration (exposed to whole-body vibration at 30 Hz and .5 G acceleration for 4 hours/day, 5 days/week for 2 weeks; vibration parameters in the present study are similar to the most common driving conditions); (4) 4-week sham control; (5) 4-week vibration; (6) 4-week vibration with human apolipoprotein A-I molecule mimetic (4F)-preconditioning; (7) 8-week sham control; (8) 8-week vibration; and (9) 8-week 4F-preconditioning group. All the rats were evaluated by behavioral, physiological, and histological studies of the brain. RESULTS: Brain injury from vibration is a cumulative process starting with cerebral vasoconstriction, squeezing of the endothelial cells, increased free radicals, decreased nitric oxide, insufficient blood supply to the brain, and repeated reperfusion injury to brain neurons. In the 8-week vibration group, which indicated chronic brain edema, shrunken neuron numbers increased and whole neurons atrophied, which strongly correlated with neural functional impairment. There was no prominent brain neuronal injury in the 4F groups. CONCLUSIONS: The present study demonstrated cumulative brain injury from MV-WBV and validated the preventive effects of 4F preconditioning.

Comparison of Peripheral Nerve Axonal Area Differences in Central and Peripheral Zones of Injured and Repaired Nerves.

BACKGROUND: Histological analysis remains a cornerstone approach for the investigation of peripheral nerve regeneration. This study investigates a newly recognized histological difference between peripheral and central zones within the regenerating nerve trunks. PURPOSE: The purpose of the study was to determine if the nerve axonal area (NXA) in regenerating peripheral nerves differs within central and peripheral areas, when viewed in cross-section. METHODS: A total of 14 rats were divided into two groups, and subjected to different injuries to the right sciatic nerve. Group 1: Transection injury with immediate repair. Group 2: Crush injury without any treatment. The left sciatic nerve was left uninjured and served as a control in each rat. Following 4 weeks of recovery, nerve trunk cross-sections were prepared. Computerized techniques were then employed to divide nerve sections into central and peripheral zones and calculate corresponding NXA values for subsequent statistical analysis. RESULTS: NXA of injured nerves was greater within peripheral as compared with the central zones, independent of injury type (p < 0.05). No statistically significant difference existed within the control groups or between the injury methods with regards to NXA regeneration extent. CONCLUSION: NXA in regenerating peripheral nerves was greater in the peripheral zones than within the central zones.

A rat model for long-gap peripheral nerve reconstruction.

BACKGROUND: The rat model has had limited utility for the study of long nerve gaps because of the small size of the animal. The authors sought to develop a simple, effective rat model for reconstruction of long nerve gap defects. METHODS: Fifteen rats had a sciatic nerve transection followed by reconstruction. Positive control rats received a 1-cm isograft. Negative control rats received a 3.5-cm hollow silicone conduit, and experimental rats received a 4-cm isograft; these were implanted in a looped configuration to accommodate the long length. Nerves were harvested at 6 weeks (1-cm grafts) and 12 weeks (3.5-cm conduits and 4-cm grafts) for histologic and histomorphometric evaluation. RESULTS: The 1-cm and 4-cm isograft groups showed robust regeneration in the distal nerve segment. The 3.5-cm hollow conduits showed absolutely no initiation of nerve regeneration. Histomorphometric values were as expected for the specified gap length. CONCLUSIONS: This study describes a simple and effective long nerve gap rat model for experiments on nerve grafts and nerve conduits. The long nerve graft model can be useful for studying techniques such as processed nerve grafts, which are currently a topic of frequent investigation. The 3.5-cm hollow conduit "no-regrowth" long-gap model is ideal for investigating conduit-based tissue-engineering solutions for long-gap nerve repair. The authors' approach overcomes the size limitation of the small animal while exploiting the features that make the rat the model of choice for preliminary nerve studies.

Qualitative effect on mRNAs of injury-associated proteins by cell phone like radiation in rat facial nerves.

Rats were exposed to cell phone radiation for 6 hours per day for 18 weeks. The buccal and mandibular branches of the facial nerve were evaluated for this study. The mRNA levels of four proteins that are usually up regulated when an injury has occurred were investigated; included were Calcium ATP-ase, Endothelin, Neural Cell Adhesion Molecule, and Neural Growth Factor. These isolated mRNAs were subjected to RT-PCR and all four were up regulated. The mandibular nerve showed a higher and broader level of up regulation than the buccal nerve. All four mRNA up regulations for the mandibular nerve and two for the buccal nerve were also statistically significant. These specific injury-related findings were mild. As the use of these cell phones continues, there most likely will be permanent damage to these tissues over the years and the likelihood of tumors, cancers, and system failures will potentially increase.

A reinvestigation of murine cranial suture biology: microcomputed tomography versus histologic technique.

BACKGROUND: Histology remains the standard form to analyze cranial suture in murine models, but this technique provides only limited "snapshots" of the entire suture and requires animal euthanasia with tissue destruction. Because of the bone complex microarchitecture, better methods are required to study the behavior of the cranial suture and its surrounding environment. The authors compared microcomputed tomography and histology as techniques to evaluate murine cranial sutures. METHODS: A total of 360 microcomputed tomography images and 160 to 170 histologic sections were processed from a mouse at postnatal days 22 and 45, respectively. After euthanasia, the posterior frontal and sagittal sutures were imaged with a microcomputed tomography system and subsequently processed for histologic analysis. Quantitative analysis of two-dimensional images was performed to determine the percentage of bone in a 1-mm sample. RESULTS: Quantitative analysis of the percentage of bone within the sutures showed identical patterns by microcomputed tomography and histology techniques. Both methods demonstrated the posterior frontal suture to have heavier fusion patterns in the anterior and endocranial portions, with variable skip areas of complete patency on the endocranial surface, ectocranial surface, or both at day 45. CONCLUSIONS: Cranial suture fusion in the murine model is not an "all-or-none" phenomenon. The posterior frontal suture, previously thought to be completely fused on day 45 by histological analysis, showed variable fusion along the length of the suture by both methods. Quantitative assessment of the percentage of bone within the posterior frontal and sagittal sutures and morphologic assessment of these sutures demonstrated similar findings by both methods. Whereas thorough histologic evaluation of an entire suture would be extremely labor intensive and impractical, these findings help to validate microcomputed tomography as a rapid and reliable method of examining the entire suture in murine models.

Evaluation of histologic changes after microdermabrasion in a porcine model.

BACKGROUND: There is a paucity of scientific information on the histologic changes associated with the clinical response to microdermabrasion. OBJECTIVE: In this study we sought to evaluate those changes in the skin after microdermabrasion, using a porcine model. METHODS: Using the left flank of an 8-week-old pig, we tattooed 4 areas with "A," "B," "C," and "D." Each of these areas was subdivided, in a gridlike fashion, from the dorsal to the ventral surface into 3 x 3-cm squares, which were numbered 1 through 8. Vacuum was initiated at 25 mm Hg the first week and increased by 5 mm Hg for each of 7 weeks to a high of 55 mm Hg in week 7. Biopsy specimens from each grid were obtained weekly. These samples were stained with hematoxylin and eosin and with the Verhoff/Van Geison (elastin) stain. Blinded histologic review of the biopsy specimens was performed by a dermatopathologist. Histometric analyses of the biopsy specimens were performed in which dermal thickness (millimeters), collagen-bundle thickness (microns), and epidermal thickness (microns) were all measured. RESULTS: Dermal thickness was increased by as much as 40% in the thinner skin and by 27% in the thicker skin. Similarly, the increase in collagen-bundle thickness was 22%, whereas the increase in the epidermal thickness was 9%. CONCLUSIONS: The findings of this preliminary study appear to indicate that microdermabrasion produces real increases in dermal thickness, collagen-bundle thickness, and epidermal thickness. Histologically, the procedure produces changes similar to those seen after dermabrasion, laser resurfacing, and chemical peels.

A modified end-to-side method for peripheral nerve repair: large epineurial window helicoid technique versus small epineurial window standard end-to-side technique.

This study evaluated 2 end-to-side nerve repair techniques for ability to induce nerve sprouting and muscular recovery. Twenty-four rats underwent identical surgeries. The helicoid method of neurorrhaphy was used on the left (large epineurial window) side and the standard end-to-side (small epineurial window) repair on the right side of each rat to repair the peroneal nerve. The helicoid configuration markedly increases the area from which axons can sprout into the recipient nerve. At 11 months after surgery, axons were counted in donor and recipient nerves, and muscle moist weight of the extensor digitorum longus (EDL) and tetanic force were measured. Muscle volume, tetanic force, and moist weight of EDL muscles were significantly higher on the left side (helicoid) than on the right (end-to-side). Histologic analysis and nerve axon counting of the recipient peroneal nerve showed significantly more regenerative nerves on the left than on the right. There were no significant differences between sites above and below the repair site in the donor tibial nerve in regard to mean number of nerve fibers. Helicoid nerve repair can entice more nerve fiber sprouts from the intact donor nerve, improve muscular recovery, and maintain donor nerve health.