Robo-Slit interactions regulate longitudinal axon pathfinding in the embryonic vertebrate brain.

The early network of axons in the embryonic brain provides connectivity between functionally distinct regions of the nervous system. While many of the molecular interactions driving commissural pathway formation have been deciphered, the mechanisms underlying the development of longitudinal tracts remain unclear. We have identified here a role for the Roundabout (Robo) family of axon guidance receptors in the positioning of longitudinally projecting axons along the dorsoventral axis in the embryonic zebrafish forebrain. Using a loss-of-function approach, we established that Robo family members exhibit complementary functions in the tract of the postoptic commissure (TPOC), the major longitudinal tract in the forebrain. Robo2 acted initially to split the TPOC into discrete fascicles upon entering a broad domain of Slit1a expression in the ventrocaudal diencephalon. In contrast, Robo1 and Robo3 restricted the extent of defasciculation of the TPOC. In this way, the complementary roles of Robo family members balance levels of fasciculation and defasciculation along this trajectory. These results demonstrate a key role for Robo-Slit signaling in vertebrate longitudinal axon guidance and highlight the importance of context-specific guidance cues during navigation within complex pathways.

Helical growth of hyphae of Candida albicans.

When grown on a range of surfaces in conditions favouring hyphal growth, hyphae of Candida albicans grew in a right-handed helical fashion. This phenomenon was observed with eight strains and with two nutrient media. It is suggested that this is a result of rotation of the hyphal apex as it extends, which on some surfaces results in a helical hyphal wall, but which in a liquid results in a straight hypha. The consequence is that on a surface, a helically growing hypha will be exposed to a more diverse environment than a straight hypha. This phenomenon may have significance in the colonization of tissue by C. albicans.

Graded work exposure to promote work return after severe hand trauma: a replicated study.

Fifty-one patients with posttraumatic stress disorder after work-related hand injuries were placed on a graded work exposure program to facilitate return to work. These patients consisted of an initial group of 25 patients and a replication group of 26 patients. The program returned 92% of the initial group and 88% of the replicated group to work with their previous employers. At 6-month follow-up, 88% of the initial group and 80.1% of the replication group were still working full-time at the jobs to which they had returned. All of the patients not working with their previous employer at follow-up had appraisal/projected flash-backs, which have previously been associated with a 90% failure to return to work. This intervention was successful with 73% of the patients experiencing such flashbacks. In conclusion, graded work exposure was an effective treatment to promote return to work for patients experiencing significant psychological symptomatology after severe hand injury.

Psychological adjustment following work-related hand injury: 18-month follow-up.

Severe, work-related hand injuries are often accompanied by a significant number of psychological symptoms that are frequently associated with posttraumatic stress disorders. These symptoms occur in the following four domains of psychological functioning: cognitive, affective, physiological, and behavioral. This study examined the incidence of a variety of symptoms occurring with work-injured patients. Interviews were conducted at 1 week, 3 months, 6 months, 12 months, and 18 months after injury. Symptom frequencies were recorded. The results indicate that many of these symptoms were persistent 18 months later and continued to be significantly debilitating. The results support the need for psychological intervention after severe, work-related hand injuries.

Tire explosion injuries to the upper extremity.

Several articles have been published that bring attention to the destructive potential of tire explosions. Although the severity of tire explosion injuries to the head and neck region is well established, only one previous article has reported injuries to the upper extremity. Fourteen patients with upper extremity tire explosion injuries have been treated by us from 1980 to 1988. Each injury was caused by single-piece wheel assemblies, as opposed to multipiece wheel assemblies, which have traditionally been associated with the injury. Three representative patient reports are discussed. Prevention of this injury can be achieved by increased public awareness, formal industrial safety training, tire servicing with dedicated equipment including restraining devices or barriers, complete evaluation of wheel/tire serviceability before tire mounting, separation of servicing of single and multipiece wheels, and complete tire deflation before servicing.

Thermal self-regulation for pain control in reflex sympathetic dystrophy syndrome.

Reflex sympathetic dystrophy syndrome is comprised of a variety of changes in vasomotor and trophic responsivity, as well as, stiffness, edema and severe pain. This study examined 20 patients with reflex sympathetic dystrophy syndrome who had failed to respond to a variety of techniques commonly used to treat this disorder. These patients had documented histories of reflex sympathetic dystrophy syndrome ranging from 18 to 60 months. All had been referred for psychological evaluation and provision of pain management. A combination of thermal biofeedback, relaxation training, and supportive psychotherapy were used to reduce subjective pain. The results indicate that patients were able to significantly increase their initial (p less than 0.0001) and postrelaxation (p less than 0.0001) hand temperatures, as well as to significantly reduce their subjective pain ratings (p less than 0.0001). This reduction in pain was maintained at 1-year telephone follow-up, with 14 of the 20 patients returning to work by that time. This intervention was effective as a pain reduction strategy for our patients with reflex sympathetic dystrophy syndrome who had failed to benefit from other treatments.

On-site work evaluations: desensitisation for avoidance reactions following severe hand injuries.

This study examined on-site work evaluations as an environmental exposure strategy to promote return to work in 15 recalcitrant patients who had failed to benefit from established methods of reducing post-traumatic stress disorder symptoms. Following the on-site work evaluation, 87% of these patients were able to use visualisation of the work setting to further desensitize themselves and returned to work within the next eight weeks. All 87% have continued to be employed at six and twelve month follow-ups. This approach holds promise for assisting patients with hand injuries who develop post-traumatic stress disorder and fail to respond to traditional psychological strategies.

Sexual dysfunction following traumatic hand injury.

The purpose of this study was to examine the frequency and nature of sexual dysfunction present in a population with traumatic hand injuries. One hundred twenty patients were seen for psychological evaluation during the first two months postinjury. Forty-nine percent (59) reported sexual dysfunction during the initial two months. Six months postinjury 19% (23) continued to have sexual dysfunction. At that time a more extensive sexual history was obtained. Three categories of sexual dysfunction were identified following interviews: (1) impotence (35% or 8 patients), (2) reduced sexual desire (65% or 15), and (3) rejection of sexual contact by the partner (39% or 9). Four major causes of impaired sexual functioning were reported: (1) pain (22% or 5 patients), (2) deformity anxiety (52% or 12), (3) replant anxiety (9% or 2), and (4) contagious anxiety (39% or 9). The results of this study indicate that persistent sexual dysfunction may be a major difficulty following hand trauma. The type of dysfunction as well as the perceived cause of dysfunction are not the same for each case. Consideration of each is necessary to design efficacious intervention strategies.

Early psychological aspects of severe hand injury.

We investigated the incidence and nature of psychological symptoms occurring during the first two months after severe hand injuries. 94% of patients had significant symptoms at some point early in rehabilitation, including nightmares (92%), flashbacks (88%), affective lability (84%), preoccupation with phantom limb sensations (13%), concentration/attention problems (12%), cosmetic concerns (10%), fear of death (5%), and denial of amputation (3%). Two months later, flashbacks (63%) remained pronounced. Nightmares (13%), affective lability (48%), concentration/attention problems (5%), fear of death (0%), and denial of amputation (0%) declined markedly, while cosmetic concerns (17%) and preoccupation with phantom limb sensations (17%) increased. Based on these findings, we believe that psychological treatment should often be given as part of the rehabilitation process.

Flashbacks after traumatic hand injuries: prognostic indicators.

Flashbacks of a traumatic hand injury may compromise a patient's rehabilitation process. This study examined the nature and significance of these flashbacks in a work-injured population. We also evaluated the ability of these patients to return to work at the site of the original injury. Sixty-one patients with work-related, traumatic hand injuries received psychological evaluation and treatment. All patients experienced flashbacks. The following three types of flashbacks were identified: (1) a replaying of the events occurring just before the accident and continuing until the injury (replay flashbacks), (2) an image of the injured hand just after the trauma occurred (appraisal flashbacks), and (3) images in which an injury that was more severe than the one that actually occurred were perceived (projected flashbacks). Regardless of the result of injury, patients with replay flashbacks were the most likely to return to their former employment (95.2%) after only 4.8 1-hour sessions of psychotherapy for control of symptoms. Patients with a combination of appraisal and projected flashbacks were the least likely to return to work (10.3%), despite the fact they received an average of 13.1 1-hour sessions of psychotherapy.