Comparison of wheelchair securement systems designed for use in large accessible transit vehicles (LATVs).

Design challenges in wheelchair securement for fixed-route, large accessible transit vehicles (LATVs) often create difficulties for passengers who use wheelchairs and operational inefficiencies for public transit agencies. Recent innovations in wheelchair securement technology for LATVs may reduce these challenges. This study explored the usability of three commercially available wheelchair securement systems in a static laboratory environment: a four-point, forward-facing (4P-FF) securement system, a three-point, forward-facing (3P-FF) securement system, and a semi-automated, rear-facing (SA-RF) securement system. Three groups of mobility device users (manual wheelchair users, power wheelchair users, and scooter users) (n = 36) completed wheelchair securement tasks in a full-scale mock-up of an LATV. For the 19 participants who did not use the occupant restraint system (ORS), perceived usability and securement time were compared across the securement systems. Using multiple usability rating scales, most participants reported that each of the systems would be acceptable for regular use. However, the majority indicated an overall preference for the SA-RF, and most rated the SA-RF system as easier, faster, and requiring less assistance to use than the 4P-FF and 3P-FF systems. Alternatives to conventional 4P-FF wheelchair securement in LATVs may thus improve boarding efficiency and transit independence of passengers who use wheelchairs.

The sleep macroarchitecture of children at risk for depression recruited in sleep centers.

OBJECTIVE: The primary aim of this study was to compare the sleep macroarchitecture of children and adolescents whose mothers have a history of depression with children and adolescents whose mothers do not. METHOD: Polysomnography (PSG) and Holter electroencephalogram (EEG) were used to compare the sleep architecture of 35 children whose mothers had at least one previous depressive episode (19 boys, aged 4-18 years, "high-risk" group) and 25 controls (13 males, aged 4-18 years, "low-risk" group) whose mothers had never had a depressive episode. The total sleep time, wakefulness after sleep onset (WASO), sleep latency, sleep efficiency, number of awakenings per hour of sleep, percentages of time spent in each sleep stage, rapid eye movement (REM) latency and the depressive symptoms of participants were measured. RESULTS: In children (4-12 years old), the high-risk group exhibited significantly more depressive symptoms than controls (P=0.02). However, PSG parameters were not significantly different between high-risk children and controls. In adolescents (13-18 years old), the high-risk subjects presented with significantly more depressive symptoms (P=0.003), a significant increase in WASO (P=0.019) and a significant decrease in sleep efficiency compared to controls (P=0.009). CONCLUSION: This study shows that children and adolescents born from mothers with a history of at least one depressive episode had significantly more depressive symptoms than controls. However, only high-risk adolescents presented with concurrent alterations of sleep macroarchitecture.

Painful seizures with allodynia in an 11-year-old boy.

An 11-year-old boy's epileptic seizures started with a feeling of impending crisis, dizziness, headache, and a bad taste in the mouth. This was followed by swallowing and a burning sensation in the left hand. At the same time, other parts of the body experienced allodynia. MRI and CT scans showed a right anteromesial temporal lesion which proved at neuropathology to be a ganglioglioma. Lesionectomy resulted in complete cessation of seizures. Seizures were absent at an 18-month follow-up. Allodynia is discussed in relation to the locality of the lesion.

Light-microscopic localization of somatostatin binding sites in the locus coeruleus of the rat.

Somatostatin (SS14) binding sites within locus coeruleus (LC) were localized at the light microscope level by [125I][Tyr0,D-Trp8]SS14 radioautography combined with an immunohistochemical/neurotoxic lesioning approach. In intact rats, the dense accumulation of SS14 binding sites of LC conspicuously overlapped with the cluster of tyrosine hydroxylase (TH) immunoreactive neurons; SS14 specific binding was directly proportional to the number of TH immunostained (TH+) cell bodies per mg of tissue throughout LC. Complete lesion of catecholaminergic nerve cell bodies of LC by intracerebroventricular injection of 6-hydroxydopamine (6-OHDA) resulted in the total abolition of SS14 specific binding in the structure. In addition, specifically bound [125I][Tyr0, D-Trp8]SS14 and TH+ cell density were quantified serially in a set of rats bearing various partial neurotoxic lesions; a highly significant correlation was found between the two parameters at each of the 16 coronal levels of LC examined. The coefficient of proportionality was identical at all levels. These results strongly suggest that somatostatin binding sites are uniformly localized on all noradrenergic neurons of LC.

Systemic naloxone does not affect pain-related behaviour in the formalin test in rat.

The effects of systemic naloxone on pain behaviour in rats were examined in modified formalin test. Dilute formalin was subcutaneously injected in the plantar surface of the hindpaw, after which pain was rated according to behavioural criteria. Fifteen minutes after formalin injection, naloxone in various doses (10 micrograms/kg, 100 micrograms/kg, 300 micrograms/kg, 600 micrograms/kg, 800 micrograms/kg, 2000 micrograms/kg) or saline was intraperitoneally injected. Pain behaviour in naloxone injected and saline injected rats was not different. The findings are discussed in relation to previous reports about naloxone effects on different types of pain.

Sensitization of nociceptive cutaneous nerve fibers from the rat's tail by noxious mechanical stimulation.

This single fiber study on rat tail nerve afferents attempts to establish a peripheral neural correlate for the hyperalgesia to mechanical stimulation which follows injury to the skin. Mechano-heat sensitive C fibers (MH-C or "polymodal" nociceptors) and high-threshold mechanoreceptive A delta fibers (HTM-A delta) were examined with a series of constant noxious pressure stimulations (4-6-8-4 N on 25 mm2, 120 s each, 5 min intervals). These injurious stimuli were either directed to the most sensitive spot of the receptive fields (central stimulation) or closely outside their borders (1-5 mm). With this protocol no clear sensitization was seen in MH-C fibers apart from a stronger dynamic response to central stimulation in some of them. In contrast, most HTM-A delta units, irrespective of the site of noxious stimulation, developed spontaneous activity, lowering of their von Frey thresholds and expansion of their receptive fields. All HTM-A delta units responded to outside stimulation: upon the first stimulus (4 N) there was a delayed discharge of continuously increasing frequency ("recruited response"), but the onset of the last stimulation (4 N repeated) evoked vigorous dynamic responses in many fibers. The recruitment of HTM-A delta nociceptor activity may contribute to post-injury hyperalgesia to mechanical stimulation and it may counteract adaptation of the single afferent fiber during prolonged noxious influence.

Nociceptor functions in intact skin and in neurogenic or non-neurogenic inflammation.

Acute neurogenic or non-neurogenic inflammation was elicited in skin patches innervated by the saphenous nerve of anaesthetized Sprague Dawley rats. Lambda carrageenan was used to induce non-neurogenic inflammation, mustard oil (allyl-iso-thio-cyanate) or antidromic nerve stimulation to induce neurogenic inflammation. Antidromic nerve stimulation yielded plasma extravasation but no significant sensitization of unmyelinated nociceptor units. In contrast, mustard oil and carrageenan yielded plasma extravasation and sensitization of nociceptors, though carrageenan sensitized only part of them. Sensitization resulted in ongoing spike discharges and in a shift of response curves to lower temperatures when controlled radiant heat stimuli were applied to the receptive fields. Responses to mechanical stimuli with v. FREY hairs were not significantly altered. Effects of neurogenic and non-neurogenic inflammation on unmyelinated nociceptor units are compared.

Does neurogenic inflammation alter the sensitivity of unmyelinated nociceptors in the rat?

This study on neurogenic inflammation aimed at comparing the effects of antidromic nerve stimulation and of cutaneous application of mustard oil on the mechanical and thermal sensitivity of cutaneous C-fibres in the rat saphenous nerve. They were tested with von Frey hairs and series of radiant heat stimuli in 5-min intervals before and after one of the above treatments. Antidromic electrical stimulation was effective in evoking a plasma extravasation in the saphenous region as revealed by prior intravenous injection of Evans blue. However, it did not evoke spontaneous activity in the polymodal C-fibres tested nor did it markedly affect their mechanical and thermal excitability in periods of up to 1 h after stimulation. Mustard oil, topically applied to the receptive fields, also evoked localized Evans blue extravasation and strongly affected the C-units. They responded to the application of the irritant with sustained firing; most units showed an increased thermal sensitivity after the treatment. This involved a lowering of the threshold and an increase of the suprathreshold discharge. Even low threshold mechanosensitive C-fibres transiently developed heat sensitivity. In some polymodal units a transient sensitization was followed by a persistent desensitization which abolished their thermal and mechanical sensitivity. Mustard oil application and antidromic nerve stimulation seem to be similar in evoking cutaneous vasodilation and plasma extravasation but different in inducing nociceptor sensitization.

Substance P-, somatostatin-, vasoactive intestinal peptide- and cholecystokinin-like levels in the spinal cord of polyarthritic rats.

Substance P-, somatostatin-, vasoactive intestinal polypeptide- and cholecystokinin-like levels were measured in lumbar dorsal and ventral cord of polyarthritic rats and compared with those obtained in vehicle-treated rats taken as controls. Polyarthritis decreased substance P concentration in lumbar ventral cord and increased cholecystokinin level in lumbar dorsal cord, while the other two peptides did not show any change. The results are discussed in relation to immunohistochemical data found in the literature.

Chronic lumbar intrathecal catheterization in the rat with reduced-length spinal compression.

The present paper describes an original technique, chronic lumbar catheterization of the subarachnoidal space in the rat. Introducing the catheter into the rachis directly at lumbar level reduces the length of the intrathecal catheter and, consequently, the extent of spinal cord compression. The validity of the technique is proved by the dose related effect obtained after morphine injections and the staining of the only spinal part of the central nervous system after blue-dye injections.

The effects of physiologic amounts of simple sugars on lipoprotein, glucose, and insulin levels in normal subjects.

Using a crossover design, eight healthy volunteers randomly received physiologic amounts (1/3 of each subject's total carbohydrate intake) of either fructose or sucrose as the primary source of simple sugar, incorporated into isocaloric diets comprised of typical American foods. After 7 and 14 days of consuming either of the two sugars, no change occurred in fasting glucose or insulin levels. In addition, total triglyceride, total cholesterol, low-density-lipoprotein (LDL) cholesterol, and high-density-lipoprotein (HDL) cholesterol concentrations were unaltered. Since our study used conventional foods in normal eating patterns rather than contrived formulas or excessive amounts of simple sugar, our data indicate that there is no difference between sucrose or fructose on various lipid components or glucose and fasting insulin levels in the "real world" in normal subjects.

[The function of contrast sensitivity in deprivation amblyopia]. / La fonction de sensibilité au contraste dans l'amblyopie de privation.

Visual deprivation during the first few months of life is known to result in a severe and irreversible visual deficit. Animal models of amblyopia developed during the past 20 years has considerably increased our knowledge of the "sensitive period" during which deprivation can lead to irreversible effects, and of the anatomical and physiological changes underlying this visual deficit. However precise data regarding either the duration of the sensitive period or the nature of the amblyopic deficit are still mostly lacking in humans. Preliminary results on the latter topic are reported in the present paper. Contrast sensitivity function (CSF) has been studied using stationary sinusoidal gratings in three patients with deprivation amblyopia resulting from bilateral congenital cataracts and in nine normal emmetropic subjects. Compared with these control subjects, the three amblyopic patients showed a dramatic decrease of their CSF with a maximal drop in the high and medium spatial frequency range and a relative sparing at low spatial frequencies. Within the framework of current theories of parallel processing of visual information through the geniculostriate pathway, these results indicate that early visual deprivation in man severely affects development of "sustained" channels involved in form perception. Further studies are underway to explore "transcient" channels in similar cases.