Accurate estimation of biomolecular reaction rates from binding data, when ligands in solution bind to receptors on the surfaces of cells or biosensors, requires an understanding of the contributions of both molecular transport and reaction. Efficient estimation of parameters requires relatively simple models. In this review, we give conditions under which various transport effects are negligible and identify simple binding models that incorporate the effects of transport, when transport cannot be neglected. We consider effects of diffusion of ligands to cell or biosensor surfaces, flow in a BIAcore biosensor, and distribution of receptors in a dextran layer above the sensor surface. We also give conditions under which soluble receptors can be expected to compete effectively with surface-bound receptors.

Biological Transport↗

PubMedDate not supplied

High risk pediatric emergency air transport.

INTRODUCTION: Pediatric Emergency Air Transports (PEATs) at Massachusetts General Hospital, Boston, Massachusetts, were reviewed between November 1986 and December 1987. Severity of illness, complications, and outcome of PEATs were compared with ground transports. Factors associated with PEAT survival were identified. METHODS: Severity of illness was measured using a modified Denver Patient Status Category (DPSC) method and the Therapeutic Intervention Scoring System (TISS). There were 35 PEATs (30 helicopter, five fixed-wing) and 96 ground transports. RESULTS: Mean severity of illness for patients was greater in PEAT than for the ground transport (PEAT DPSC score=4.23+/-1.06 versus ground DPSC=3.57+/-0.89 [SD], p=.0005). The PEAT mortality was associated with a greater mean severity of illness (TISS survivors=19.1+/-11.4 versus non-survivors=44.3+/-9.5, p=.0001), but not with: the presence of an on-flight physician; transport delay; transport duration; age; sex; history of chronic illness; or intra-transport medical complications. CONCLUSIONS: Compared to ground transports, PEATs were used for higher risk patients.

Adolescent↗

PubMedDate not supplied

Adult age differences in long-term semantic priming.

Young and older adults were first asked to decide if a list of individually presented words were "living" (e.g., "tree") or "nonliving" (e.g., "store"). This was termed the "orienting task." Next, subjects performed a pronunciation task. Semantic priming for young and older adults was indexed by determining if semantic congruence between words in the orienting task and words in the pronunciation task improved performance on the pronunciation task relative to pronounced words from semantic categories not primed in the orienting task. The present data, from two different experiments, revealed that subjects pronounced high-dominance exemplars of the "living" words primed in the orienting task faster than words not primed in the orienting task. These data indicated that semantic priming for relatively long prime-target stimulus onset asynchronies can occur, and that such priming is at least as robust for older adults as for young adults. The results are discussed in terms of four current models of semantic priming.

Adolescent↗

PubMedDate not supplied

Pressure ulcers in SCI: does tension stimulate wound healing?

Pressure ulcers are an immense problem among older and disabled populations. Although there are many studies in the literature about the etiology, interface pressures, natural history, and epidemiology of skin breakdown, there is relatively little information about factors that stimulate the repair of body wall tissues after breakdown. Specifically, there is a paucity of information about the effects of mechanical stress on healing. This is a particularly important consideration for those areas, such as the perineal tissues, that bear large mechanical forces. The purpose of this paper is to discuss the research that addresses skin and tissue repair in response to tension. Two case studies that support the hypothesis that tension stimulates wound healing are presented from the Spinal Cord Injury Center at the Seattle VAMC. After weeks of nonhealing, each of these cases healed within 2 weeks of initiating a range of motion program that applied tension to the nonhealing portion of a myocutaneous flap.

Adult↗

PubMedDate not supplied

Rotator cuff repairs in individuals with paraplegia.

Shoulder pain and dysfunction are common problems among those individuals with a spinal cord injury (SCI). Among individuals with SCI who have shoulder pain, the prevalence of rotator cuff tears is 65 TO 71%. To date, there has been little discussion as to the efficacy of various treatments for shoulder pain used in the SCI population. The purpose of this retrospective study was to evaluate the outcome of rotator cuff repairs at the Spinal Cord Injury Center (Veterans Administration Puget Sound Health Care System). Five patients (six shoulders) were identified who had undergone shoulder surgery for rotator cuff tear since 1987. Four individuals (five shoulders) had large rotator cuff tears, and following surgery, none of these repairs resulted in improvement of shoulder function or improvement in active range of motion. The one patient with a smaller tear limited to the supraspinatus had a successful surgical outcome in that he had decreased pain, increased strength, and increased range of motion. There is a general lack of epidemiologic information about shoulder pain in individuals with paraplegia. There is also a remarkable lack of research as to the functional impact of shoulder pain and the outcome of nonsurgical and surgical treatments. This case series, drawn from a population of 511 individuals with spinal cord injury, demonstrates that poor outcome was more likely in those with supraspinatus atrophy, those with upward displacement of the humeral head on x-ray, and in those with tears involving more than one muscle. There is a need for further study of conservative treatment and development of selection criteria for those individuals who are being considered for surgery.

Aged↗