The Complex Nature of Interactive Neuroregeneration-Related Molecules

We review the growing list of molecules that may be involved in wound healing in the central nervous system (CNS). It is known that many of these molecules are present during normal development and neoplastic growth in both neural and nonneural tissues, often in areas where pattern formation or tissue remodeling is evident; however, their functional roles are often quite elusive. In order to understand the changes that occur in and around a brain wound, we review proposed functions of neuroregeneration-related molecules in in vitro and in vivo preparations, as well as note their expression in other healing tissues including skin. A hypothesis that wound healing events in the CNS supersede neuritic growth around a lesion is presented. In contrast to the classical view of failed regeneration, there may be significant amounts of circuit reorganization that occur following injury, and such plasticity may be further enhanced by manipulating the molecular environment around a brain wound and in synaptically related structures.     

Risk of developing AIDS in HIV-infected cohorts of hemophilic and homosexual men

The latency period and/or incidence of the acquired immunodeficiency syndrome (AIDS) may differ in persons infected with the human immunodeficiency virus by different routes or having different "cofactors." We compared 79 hemophilic men in Pennsylvania and 117 homosexual and bisexual men in California, all having known dates of infection and long postinfection observation periods, to examine these hypotheses. By 1987, twenty-one percent of the hemophilic and 27% of the homosexual men had developed AIDS. However, seroconversion patterns differed for the two groups, and when this was taken into account, the conditional odds ratio for AIDS was 1.20. Kaplan-Meier survival analysis showed no significant difference in the cumulative proportion with AIDS, from time of infection. These results are limited by the small size and geographically localized nature of our study populations, but they suggest that currently the relative length of human immunodeficiency virus infection is of primary importance in comparing disease outcome for different populations.     

Inhibitory effect of amiloride and gadolinium on fine afferent nerves in the rat knee: evidence of mechanogated ion channels in joints

Synovial joints are complex sensory organs which provide continuous feedback regarding position sense and degree of limb movement. The transduction mechanisms which convert mechanical forces acting on the joint into an electrochemical signal which can then be transmitted to the central nervous system are not well understood. The present investigation examined the effect of the mechanogated ion channel blockers amiloride and gadolinium on knee joint mechanosensitivity. In deeply anaesthetised rats (sodium thiopental: 100–120 mg/kg, i.p.), single unit extracellular recordings were made from knee joint group III (Aδ) and group IV (C) primary afferents in response to mechanical rotation of the joint. Afferent firing rate was measured before and after topical application of either amiloride (0.1 mM, 1 mM) or gadolinium (250 μM) onto the receptive field of the sensory unit and recording was continued every 10 min up to a total of 50 min. With normal rotation of the knee, joint mechanosensitivity was significantly reduced by both amiloride (P<0.0001; n=10–21) and gadolinium (P=0.001; n=12) and this effect was sustained throughout the recording period. This investigation provides the first in vivo electrophysiological evidence that joint mechanotransduction involves the activation of amiloride and gadolinium-sensitive mechanogated ion channels. Future studies to determine the mechanogated ion channel subtypes present in joints and the modulation of their gating properties during inflammation may yield novel approaches for the control of arthritis pain. Funding: JJMcD is funded by the Alberta Heritage Foundation for Medical Research, the Canadian Institutes for Health Research, and the Arthritis Society of Canada.     

Effect of a CCR5 inhibitor on viral loads in macaques dual-infected with R5 and X4 primate immunodeficiency viruses

Human immunodeficiency virus type 1 (HIV-1) fusion with its target cells is initiated by sequential interactions between its envelope glycoprotein, CD4, and a co-receptor, usually CCR5 or CXCR4. Small molecules that bind to CCR5 and prevent its use by R5 HIV-1 strains are now being developed clinically as antiviral drugs. To test whether a block to CCR5 promotes the replication of viruses that enter cells via CXCR4 and are associated with accelerated disease progression, we administered a small molecule CCR5 inhibitor, CMPD 167, to three macaques dual-infected with both R5 (SIVmac251) and X4 (SHIV-89.6P) viruses. CMPD 167 caused a rapid and substantial (on average, 50-fold) suppression of R5 virus replication in each animal. In two of the animals, but not in the third, a rapid, transient, 8- to 15-fold increase in the amount of plasma X4 virus occurred. In neither animal was the increase in X4 viral load sustained throughout therapy, however. These observations may have relevance for the development of CCR5 inhibitors for treatment of HIV-1 infection of humans.     

Proanthocyanidin: a natural crosslinking reagent for stabilizing collagen matrices

While attempting to find a suitable crosslinking reagent for biopolymers, a naturally occurring proanthocyanidin (PA) obtained from grape seeds was selected to fix biological tissues. The cytotoxicity and crosslinking rate, reflected by the in vitro and in vivo degradation of fixed matrices has been studied. The shrinkage temperature of the fixed bovine pericardium increased from 66 to 86 degrees C. A cytotoxicity assay using fibroblast cultures revealed that PA is approximately 120 times less toxic than glutaraldehyde (GA), a currently used tissue stabilizer. In vitro degradation studies showed that fixed tissue was resistant to digestion by bacterial collagenase. Crosslinks between PA and tissues can be stabilized by decreasing the dielectric constant of the solution during storage. After subcutaneous implantation for periods ranging between 3 and 6 weeks, we found no apparent degradation of the GA- or PA-fixed tissues, whereas fresh tissue controls rapidly disintegrated. Beyond 6 weeks PA crosslinks began to degrade. More fibroblasts migrated and proliferated inside the PA-fixed implants compared with GA counterparts. Tissues crosslinked with PA manifested an enhanced collagen expression and deposition and did not calcify after implantation. GA, on the other hand, even after thorough rinsing continued to be cytotoxic, inhibited collagen synthesis and encouraged dystrophic calcification. Collagen matrices crosslinked with PA are expected to be of value in the design of matrices that will encourage cell ingrowth and proliferation, which are temporary in nature, and that are intended to regenerate or replace missing tissues, which can delay the biogradation of collagen. As such they should be of significant value in the emerging field of tissue engineering.     

The association between daytime sleepiness and sleep-disordered breathing in NREM and REM sleep

BACKGROUND: Daytime sleepiness is common in patients with sleep-disordered breathing. Although respiratory events during sleep are associated with the occurrence of daytime sleepiness, the differential impact of these events during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep on daytime sleepiness has not been well characterized. STUDY OBJECTIVES: To determine the effect of respiratory events during REM sleep and NREM sleep on daytime sleepiness, as assessed by the multiple sleep latency test (MSLT). DESIGN: Cross-sectional study. SETTING: University-based sleep disorders laboratory. PARTICIPANTS: Patients referred for polysomnography and daytime MSLT (n=1,821). INTERVENTIONS: N/A MEASUREMENTS AND RESULTS: The study sample was initially divided into quartiles based on the level of the apnea-hypopnea index (AHI) during NREM sleep. Within the first NREM-AHI quartile (NREM-AHI < 8.3 events/hr), the association between REM-related respiratory events and daytime sleepiness was examined using the method of Kaplan-Meier analysis and Cox proportional hazards regression. After adjusting for age, gender, body mass index, and the duration of NREM and REM sleep, REM-AHI was not associated with daytime sleepiness (Relative Risk: 1.01; 95%CI: 0.94-1.10). Similarly, no significant association was observed between REM-AHI and the MSLT in patients within the second through fourth NREM-AHI quartiles. In contrast, increasing severity of disordered breathing during NREM sleep was associated with daytime sleepiness. For a 10-point increase in NREM-AHI, the adjusted relative risks for daytime sleepiness in the second through fourth NREM-AHI quartile were 1.21 (95%CI: 1.01-1.46), 1.20 (95%CI: 1.05-1.37), and 1.10 (95%CI: 1.04-1.16), respectively. CONCLUSION: Sleep-disordered breathing during NREM sleep, but not REM sleep, is associated with increased risk of daytime sleepiness.     

Analysis of the coxsackievirus B-adenovirus receptor gene in patients with myocarditis or dilated cardiomyopathy

Myocarditis and dilated cardiomyopathy (DCM) are common causes of morbidity and mortality in children and adults, most commonly due to infection with coxsackievirus B or adenovirus. Increased expression of the common human coxsackievirus B-adenovirus receptor (CAR) has been reported in patients with DCM. We investigated the CAR gene in patients with acquired or familial myocarditis/DCM for mutations/polymorphisms. Several polymorphisms or intronic substitutions, distant from the intron-exon boundaries, were identified but no mutations. Based upon these data it appears that CAR gene mutations are not a major host determinant in the development of myocarditis and DCM.