WAVE1 and regulation of actin nucleation in myelination.

The myelin sheath can be compared to the neuronal growth cone in that the unfurled sheath looks like a giant lamellum. The authors recently tested this hypothesis by examining the importance of WAVE1, a regulator of lamellipodia formation in neurons and other cells, in myelinogenesis. They found that WAVE1 is critical for formation of oligodendrocyte lamellae and myelin sheaths. They review the regulation of WAVE1 and how WAVE1 is transported and localized to lamellipodia. Because they found that some but not all myelination was impaired by knockout of WAVE1 function, they hypothesize that other regulators of actin nucleation help oligodendrocytes produce myelin in parallel with WAVE1 function. Interestingly, they found that oligodendrocyte maturation also is disturbed with WAVE1 knockout and propose that proper localization and transport of signaling molecules relevant to the integrin signaling cascade are disrupted by loss of WAVE1 function.     

Gonadal steroid preservation of central synaptic input to hamster facial motoneurons following peripheral axotomy

In recent work, we have demonstrated that testosterone propionate accelerates recovery from facial nerve injury in the adult male hamster. Central synaptic stripping following peripheral motor neuron damage is a well-established component of the injury response. Gonadal steroids regulate synaptogenesis in the normal nervous system. In this study, we tested the hypothesis that testosterone propionate administration at the time of facial nerve transection alters the synaptic connectivity of injured facial motoneurons. Adult hamsters were subjected to right facial nerve transection at the level of the stylomastoid foramen. Half the animals received subcutaneous implants of testosterone propionate; the other half were sham implanted. At 5 days postoperative, the animals were killed by intracardiac perfusion-fixation, and the control and axotomized facial nuclear groups from the brainstems of nonhormone- and testosterone propionate-treated animals processed for routine transmission electron microscopy. Quantiative analysis of the synaptic ratio (percent somal membrane covered by synaptic profiles) and the average length of axosomatic synapses was accomplished. The results indicate that axotomy alone resulted in an 81% reduction in the synaptic ratio and a 26% decrease in the average synaptic length of axosomatic synapses. Exposure to testosterone propionate from the time of facial nerve transection resulted in only a 48% reduction in the synaptic ratio and a 16% decrease in the average synaptic length of axosomatic synapses following injury. Thus, testosterone propionate significantly attenuated the amount of synaptic stripping that occurred at 5 days postoperative and the decrease in average length of the remaining synapses as well. It is concluded that gonadal steroids modulate central synaptic plasticity following peripheral nerve injury. The results are discussed in light of our recent findings of steroidal effects on the central astrocyctic response to facial nerve injury as well.     

Ascorbic acid, HDL, and total plasma cholesterol in the elderly

The relationships between ascorbic acid (plasma and dietary) and plasma HDL cholesterol (HDL-C), total plasma cholesterol (T-C) and T-C:HDL-C ratio were examined in a population of 235 males and 445 females, age 60-98 years. Many known or suspected determinants of HDL-C and T-C, including age, sex, triceps skinfold thickness, fasting blood glucose, alcohol intake, and others, were considered as covariates due to their potential confounding or modifying effects on the relationships under study. The results show that plasma ascorbic acid is significantly (p less than 0.05) correlated with HDL-C (r = 0.09), T-C:HDL-C (r = 0.10), but not with T-C (r = 0.03). There is a strong age interaction with the largest effect of ascorbic acid in the youngest age group studied (60-69 years). The effects of dietary ascorbic acid are similar but slightly reduced in magnitude.     

Neuropathology and Molecular Studies of a Patient with Tourette Syndrome and Huntington Disease

This paper reviews the association of Huntington's Disease (HD) and tic disorder or Tourette Syndrome (TS) We also present the results of a follow-up study of a male with childhood-onset TS and adult-onset HD who died at 45 years of age. The developmental course and results of neuropathologic and molecular studies of this patient are reported. This is the first case of childhood onset of TS with adult onset of HD reported who has come to autopsy. A developmental model for childhood and adult neuropsychiatric disorders is presented.     

Histological comparison of implanted cadaveric and porcine dermal matrix grafts.

OBJECTIVES: Histological comparison of human-based (AlloDerm) and porcine-based (ENDURAGen) dermal matrices regarding tissue incorporation and neovascularization as potential soft tissue augmentation materials. STUDY DESIGN: In vivo, rat model. METHODS: Subcutaneous implantation of 1-mm thick, 1 cm x 1 cm pieces of AlloDerm, ENDURAGen, and meshed ENDURAGen was performed in 24 Sprague Dawley rats. Implant materials were harvested at 4 (n = 12) and 8 weeks (n = 12). Histological quantification of soft tissue ingrowth and microvascular density was performed following hematoxylin-eosin staining and CD34 immunohistochemistry, respectively. RESULTS: AlloDerm showed significantly greater soft tissue ingrowth and microvascular density compared with both ENDURAGen and meshed ENDURAGen at 4 and 8 weeks (P < 0.001). CONCLUSIONS: Although these results may differ in human host tissues, AlloDerm seems to be a more suitable dermal matrix implant than ENDURAGen for cases in which tissue incorporation and neovascularization are sought for the optimal outcome based on this animal model.     

Panic disorder and the vestibular system

This article reviews the interrelationship between panic disorder and vestibular function. There is a possibility of both somatopsychic and psychosomatic interactions between panic and the vestibular system. Another possibility is that vestibular dysfunction could be associated with certain mental disorders, including panic disorder, as a nonspecific marker. Somatopsychic interactions are suggested by findings of high prevalence of vestibular dysfunction in selected patients with panic disorder, by the occurrence of "space and motion phobia" in patients with panic disorder, and by the report of anxiety and pseudoagoraphobia in some patients with a primary complaint of vertigo. Psychosomatic influences include symptoms of dizziness and increased sensitivity of the vestibular system due to anxiety or hyperventilation. Vestibular dysfunction as a nonspecific marker is discussed in the context of a review of studies of the vestibular system in schizophrenia. Before more definite conclusions can be drawn whether panic disorder is related to vestibular dysfunction in some cases, further research is needed to establish the specificity of vestibular dysfunction for panic disorder.     

Adequacy of "Hot Biopsy" for the Treatment of Diminutive Polyps: A Prospective Randomized Trial

Patients with diminutive polyps in the rectum or sigmoid colon were randomized to "hot biopsy" treatment for either 1) electrocautery for 2 s (fixed duration cautery) or 2) cautery until visible necrosis of the polyp base was evident (variable duration cautery). Sigmoidoscopy was performed 4 wk after treatment to determine the adequacy of polyp eradication. In the fixed duration cautery group, 11 of 21 polyps (52%) were eradicated, compared with 12 of 14 polyps (86%) in the variable duration cautery group (p = 0.04). When analyzed according to whether or not visible necrosis was achieved (some of the polyps in the fixed duration cautery group showed necrosis with 2 s cautery), 19 of 23 polyps (83%) were eradicated when necrosis was evident, compared to 5 of 12 (42%) without necrosis (p = 0.004). We conclude that hot biopsy treatment for diminutive polyps is significantly more effective when visible necrosis is achieved during cautery. Furthermore, even with visible necrosis, there is a 17% failure rate of polyp eradication.