Biomedical subjects
Publications and source records attributed to J P Nelson.
The use of photography is described as a method embedded within an ethnographic investigation of rural home care for older adults. Photography fostered data generation, elicited participants' stories, and illustrated patterns of rural aging. Analysis of photographic data pooled with interview and observational data facilitated an in-depth understanding of rural aging and home health care.
A 69-year-old man with a total hip prosthesis, recurrent infection, and intrapelvic incarceration of the acetabular components required extraction of a long-stem total hip prosthesis through three incisions. Retroperitoneal intrapelvic extraction of the incarcerated prosthesis was necessary. This approach allowed removal of intrapelvically migrated components and the eradication of the infection. The patient had no signs of infection five years postoperatively.
The value of the vascular examination cannot be over-estimated. Symptoms of vascular disease present in the foot and lower extremity may actually be manifestations of severe life-threatening disease. Symptoms, their location, and the frequency and quality of the patient's pain often provide valuable clues for the clinician's diagnosis. Central nervous system symptoms, ocular disturbances, cardiac symptoms, impotence, or constitutional disturbances may all indicate systemic arterial disease. Risk factors for this disease include smoking, hypertension, hyperlipidemia, genetic predisposition, diabetes, emotional stress, and physical inactivity. Those factors attributable to hypercoagulability and venous disease are birth control pill use, estrogen chemotherapy, obesity, prolonged immobilization, paralysis, previous thrombotic episodes, venous stasis disease, and varicose veins. An accurate bilateral assessment of blood pressure, pulses, and capillary perfusion is of critical importance. Careful inspection of the extremity for trophic changes, skin color, texture, temperature, edema, ulceration, atrophy, or paresis, will provide clues of vasculopathy. A relatively accurate assessment of circulatory status may be obtained without the use of exotic instruments. Simple tests such as the elevation and dependency tests, capillary bed return test, venous filling time test, along with blood pressure, pulse, and possibly oscillometry data are valuable in arterial evaluation. Such venous tests as inspection, percussion, Homan's sign, Trendelenburg, and Perthes' tourniquet are useful in the determination of the presence of venous disease. Fortunately, over the past few years tremendous advances have been made in the technology of the vascular laboratory. If symptoms are discovered during the vascular history and physical examination, the complete noninvasive study will provide impressive data to quantitate and specifically establish the diagnosis.
Psychiatric inpatients with dementia (N = 61) or depression (N = 67) in late life were 2.6 times more likely to manifest magnetic resonance imaging abnormalities of the brain than were elderly controls (N = 44). Controlling for the effects of age and gender, demented patients were distinguishable from controls by an increased prevalence of cortical atrophy and infarction, while depressed patients exhibited an increased prevalence of cortical infarctions and leukoencephalopathy. Patients with dementia were distinguishable from those with major depression by an increased prevalence of cortical atrophy. These results indicate that major depression in late life, like dementia, is associated with a remarkable increase in overt pathologic changes in the brain.
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This report documents another case of malignancy associated with total hip replacement. A malignant fibrous histiocytoma of the femur was diagnosed approximately 10 years after insertion of a cemented Müller cobalt-chromium prosthesis.
In an effort to determine the clinical usefulness of Apgar scoring and cord pH in neonatal management, specimens of umbilical cord blood were obtained after 257 of 329 consecutive deliveries at a community-based hospital. A notable number of babies who were born in a vigorous state were in fact acidotic (umbilical arterial pH greater than 1 SD below mean). Seventy-two percent of acidotic babies had an Apgar score greater than 7 at 1 minute, and 92% had an Apgar score greater than 7 at 5 minutes. Correlation coefficients of Apgar scores at 1 and 5 minutes and arterial pH with the health status of newborn infants were poor. A chi 2 analysis of arterial pH and Apgar scores at 1 and 5 minutes indicated that a larger number of sick babies had an Apgar score less than 7 and acidosis than expected by pure chance. However, the sensitivity values of the Apgar score at 1 minute (0.48) and 5 minutes (0.24) and the arterial pH (0.40) for predicting sick children limit the clinical usefulness of these tests. While technically feasible in a community hospital, routine cord pH measurements add little to neonatal evaluation and management.
In a prospective study of EEG sleep patterns in 25 elderly depressives, 25 elderly demented patients, and 25 healthy, elderly control subjects, the sleep of depressives was characterized by reduced REM sleep latency, increased REM percent and first REM period density, and altered temporal distribution of REM sleep, as well as by diminished sleep maintenance (correlated significantly with Hamilton ratings of depression: multiple R = -0.42, p less than 0.05). In contrast, the sleep of demented patients showed reduced REM sleep percent, but normal REM temporal distribution, increased loss of spindles and K-complexes (the latter correlating significantly with severity of cognitive impairment as measured by the Folstein score: multiple R = -0.59, p less than 0.01), and less severe sleep maintenance difficulty than for depressives. An examination of REM latency demonstrated a skewed distribution in depression (i.e., 42% of nights with sleep-onset REM periods), but a normal distribution in the controls and demented subjects. A REM latency cut-off score of 30 min correctly classified 68% of all patients (kappa = 0.36; p less than 0.005), compared with 78% correctly identified in our retrospective study (Reynolds et al. 1983).
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A pacemaker that increases pacing rate in response to exercise enables the pacemaker patient to improve his state of well-being. Possible sensors include atrial rate, Q-T interval, pH, venous oxygen saturation, respiratory rate, cardiac output, body motion, and blood temperature. To determine the efficacy of right ventricular blood temperature as an indicator of exercise, an experimental temperature-controlled pacemaker was developed and was evaluated in dogs. A resulting algorithm was implemented in a microcomputer-based VVI pacemaker which reliably detected exercise and rest from blood temperature when totally implanted. The pacemaker generated two pacing rates to provide increased cardiac output. Data is being obtained to establish feasibility in humans.
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Eye movement related potentials were recorded bilaterally from the lateral geniculate body and visual cortex in five cats during REM sleep and waking. During REM sleep polygraphic recordings showed that these potentials have significantly greater amplitudes (primary waves) in the visual cortex and lateral geniculate body ipsilateral to the direction of the corresponding rapid eye movements. This amplitude difference was seen as a mean increase of 38.2% over the contralateral side and was found in 94.0% of wave pairs. The correlation between horizontal eye movement direction and amplitude of the waves is specific to REM sleep as there were no measurable differences in the waking state. These results are discussed with respect to possible mechanisms and functions of this lateralized wave system and its state dependency.
Extracellular microelectrode recordings were made from single neurons in the pontomesencephalic brain stem of head-restrained but nonanesthetized cats whose behavioral state was continuously monitored polygraphically. A population of neurons was encountered with the unusual property of progressively decreasing discharge rate as the cats passed from waking (W) through synchronized sleep (S) to desynchronized sleep (D). In many cases there was a complete cessation of firing in desynchronized sleep, suggesting the designation D-off cell for this neuronal subtype. The D-off cell population was distributed in a bandlike zone across the brain stem at the pontomesencephalic junction with dense concentration of cells in aminergic nuclei: the serotonergic dorsal raphe and raphe linearis centralis and noradrenergic locus ceruleus and peribrachial regions. Aside from a sparse distribution in the central tegmental field, there were no D-off cells in pontine reticular nuclei where cells of the D-on type abound. The proportion of cells showing the D-off property and the magnitude of the state-related change were correlated across nuclear groups as follows: raphe and peribrachial (highest), locus ceruleus (intermediate), and reticular (lowest) for both values. The firing rates of D-off cells tended to be low in waking with very regular interspike intervals. This characteristic firing pattern and the anatomical distribution suggests that D-off cells may be tentatively identified as aminergic. The marked contrasts in aminergic neuronal activity between waking and desynchronized sleep are interpreted as possibly playing a role in state generation through progressive distribution of cholinergic neurons postsynaptic to the D-off cell population. Predictable results would not only be a change in the excitability of the postsynaptic population but also a change in response mode related to a shift in neurotransmitter throughout the brain.
Pontogeniculooccipital (PGO) waves appeared almost simultaneously in both lateral geniculate nuclei (LGB), but in each case on had a larger amplitude and preceded the other by a few milliseconds. The larger, earlier wave is called the primary wave. Primary waves were found to appear with equal frequency in each LGB. During rapid eye movement sleep (REM sleep), LGB primary waves were ipsilateral to the direction of rapid eye movements. During REM sleep a group of cat midbrain neurons, which we call PGO burst cells, fired in stereotyped bursts at fixed latencies before ipsilateral primary waves, but they almost never fired bursts when the primary waves were contralateral. PGO burst neuron discharge also correlated with the direction of rapid eye movements during REM sleep. In wakefulness, PGO burst cells fired single spikes, not bursts, which had some correlation with LGB waves when averaged by computer. The results suggest that PGO burst cells are output elements in the PGO wave-generation system ad that PGO waves convey eye movement information to the sensory visual system in REM sleep. They also may have a role in the production of saccade-related waves in the visual system during wakefulness.
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The role of the operating room environment in the development of deep sepsis after total hip arthroplasty was studied at four centers. The incidence of deep sepsis after 5,865 total hip arthroplasties performed in the four centers varied from 0.5% to 2.3%. Procedures performed in a conventional operating room were associated with the highest incidence of deep sepsis (1.3%). The use of a vertical, unidrectional airflow system with a helmet aspirator suite was associated with the lowest incidence of deep sepsis (0.6%). Although patients with previous hip surgery had an increased incidence of deep sepsis regardless of the operating room environment, those procedures performed in a vertical, unidrectional facility had a lower incidence of deep sepsis. Newer techniques designed for the reduction of airborne contamination of the operative wound seem to reduce the incidence of deep-wound sepsis after total hip arthroplasty, especially in patients with previous hip surgery.
A newly discovered class of neurons, ponto-geniculo-occipital (PGO) burst neurons, has PGO wave relationships of phase-leading, stereotyped discharge bursts, and the highest reported discharge specificity and coherence; these neurons thus fulfill correlative criteria for output generator neurons for PGO waves. The PGO burst neurons are recorded in a discrete dorsal brainstem area in apposition to the brachium conjunctivum.
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