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Biomedical subjects

S McKernan

Publications and source records attributed to S McKernan.

7 recordsLinked to original sources

Managed care for uninsured patients at an academic health center: a case study.

In 1997, the University of New Mexico Health Sciences Center ("the Center") created a managed care plan ("the Plan") for its uninsured patients who were county residents. The Plan's features include pooling the resources of existing county safety-net providers, enrolling patients with primary care providers at easily accessible neighborhood-based clinics, and investing in social support services, case management, and 24-hour telephone triage. After two years of the Plan's operation, the utilization of ambulatory care services by Plan enrollees, the number of discharges per 1,000 enrollees from the Center-affiliated University Hospital, and the number of hospital days per 1,000 enrollees had all dropped significantly (p < .001 for all). For the 13,114 enrollees in the Plan, University Hospital saved an estimated $1,904,872 per year in costs. The replacement of unpaid hospital days with paying patients is estimated to have yielded over $695,000 in additional revenues per year. The authors conclude that managing the care of uninsured patients in an academic health center can reduce ambulatory care and inpatient utilization and reduce the cost of care. To achieve these favorable outcomes requires the organization of services to meet the unique needs of the uninsured and underserved population.

Academic Medical Centers↗

Characterization of the Absolute Crystal Polarity across Twin Boundaries in Gallium Phosphide Using Convergent-Beam Electron Diffraction.

: The measurement of absolute crystal polarity is crucial to understanding the structural properties of many planar defects in compound semiconductors. Grain boundaries, including twin boundaries, in the sphalerite lattice are uniquely characterized by the crystallographic misorientation of individual grains and the direction of the crystal polarity in domains adjoining the grain boundary. To evaluate crystal polarity in gallium phosphide (GaP), asymmetrical interference contrast in convergent-beam electron-diffraction (CBED) patterns was used to ascertain the nature and direction of polar bonds. The direction of the asymmetry in the electron diffraction reflections was correlated with the crystal polarity of a sample with known polarity. The CBED technique was applied to determine the polar orientation of grains adjoining Sigma = 3 coherent and lateral twin boundaries in polycrystalline GaP.

Journal Article↗

Microvascular skin responses in elderly people with varicose leg ulcers.

The function of cutaneous primary afferent unmyelinated nerves (C-fibres) was assessed by measuring axon reflex vasodilatation in the skin over the arms and feet of 15 elderly patients with chronic venous ulcers using a laser Doppler flowmeter. Dilatation of skin microvasculature in response to nerve-independent stimuli was also assessed. Results were compared with those of control subjects matched for age and sex. The chronic venous ulcer group showed reduced axon reflex vasodilatation in the feet but not the arms. Response to nerve-independent vasodilators was similar in both ulcer patients and controls in arms and feet. Local impairment of C-fibre function may partly explain the increased incidence and resistance to healing of leg ulcers in old people.

Aged↗

Effects of age on the axon reflex response to noxious chemical stimulation.

The axon reflex flare response to noxious stimulation of the skin is mediated by polymodal nociceptors of "C" fibre primary afferent nerves. Topical application of capsaicin initiates such a flare. The mediator of the response is presumed to be substance P. In this study we examined the flare response to topical capsaicin (1g/L in 70% alcohol for 30 minutes; n = 220) and the substance P content of autopsied skin (3mm punch biopsy; n = 14). The area of the flare response was measured by tracing a Leitz ASM probe onto traced flare outlines. Skin was extracted in acetic acid and acetone and substance P measured by radio-immunoassay. Skin thickness was also measured in parallel biopsy specimens. The flare response decreased with increasing age at sites examined on the trunk and proximal extremities (for the trapezoid ridge r = -0.41; p less than 0.001). The substance P content of skin also decreased with age at those sites examined (for the cubital fossa r = -0.57; p less than 0.05). There was no relationship between age and skin thickness. The results demonstrate decreased activity of the axon reflex mechanism with increasing age. This may be due to changes in substance P containing nerve terminal density. The importance of a reduced neurogenic inflammatory response in the pathology of ageing is unknown.

Adult↗

Neurogenic flare responses following topical application of capsaicin in humans.

The flare response to noxious stimulation of the skin is mediated by polymodal nociceptors of C fiber primary afferent nerves. Topical application of capsaicin initiates a flare response and burning pain. In this study, the variability of capsaicin-induced flare and pain was assessed in 220 subjects. The major factors in flare response are body site and age; more severe reactions occur in more proximal sites and in younger subjects. Larger flares were shown to be associated with greater pain. Variability is probably due to differences in the structure and reactivity of the neurovascular unit as proposed in the Lewis model of the axon reflex. It may prove possible to assess polymodal nociceptor function using topical capsaicin in disease states that affect the peripheral terminals of primary afferent nerves.

Administration, Topical↗