Effects of a normothermic dressing on pressure ulcer healing.

OBJECTIVE: To determine the effects of radiant heat applied through a semiocclusive dressing on periwound skin temperature and wound healing. DESIGN: Before-after trial. SETTING: Spinal cord injury and geriatric units of a VA medical center. PATIENTS: Twenty inpatients with 21 Stage III and IV pressure ulcers. INTERVENTIONS: A semiocclusive, heated dressing was applied to 15 Stage III and IV pressure ulcers for 4.5 hours, Monday through Friday, for 4 consecutive weeks. The dressing emitted heat at 38.0 degrees C for 2 60-minute periods daily. At all other times, the wounds received only standard wound care. Six wounds in a separate control group received only standard wound care during the same 4-week period. MAIN OUTCOME MEASURES: Periwound skin temperature within and adjacent to the dressing and measurements of wound surface area. MAIN RESULTS: Mean skin temperatures inside and outside the heated dressing increased by 0.97 degree C and 1.08 degrees C (P < .05), respectively, from baseline values. Wounds treated with standard care plus the heated dressing underwent a statistically significant reduction in mean surface area of 60.73%. Wounds in the control group underwent a statistically insignificant reduction in mean surface area of 19.24%. CONCLUSION: Wounds treated with a radiant heat dressing healed significantly faster than wounds that received only standard care. There were no adverse effects from the radiant heat dressing.

Directed and enhanced neurite growth with pulsed magnetic field stimulation.

Pulsed magnetic field (PMF) stimulation was applied to mammalian neurons in vitro to influence axonal growth and to determine whether induced current would direct and enhance neurite growth in the direction of the current. Two coils were constructed from individual sheets of copper folded into a square coil. Each coil was placed in a separate water-jacketed incubator. One was energized by a waveform generator driving a power amplifier, the other was not energized. Whole dorsal root ganglia (DRG) explant cultures from 15-day Sprague-Dawley rat embryos were established in supplemented media plus nerve growth factor (NGF) at concentrations of 0-100 ng/mL on a collagen-laminin substrate. Dishes were placed at the center of the top and bottom of both coils, so that the DRG were adjacent to the current flowing in the coil. After an initial 12 h allowing DRG attachment to the substrate floor, one coil was energized for 18 h, followed by a postexposure period of 18 h. Total incubation time was 48 h for all DRG cultures. At termination, DRG were histochemically stained for visualization and quantitative analysis of neurite outgrowth. Direction and length of neurite outgrowth were recorded with respect to direction of the current. PMF exposed DRG exhibited asymmetrical growth parallel to the current direction with concomitant enhancement of neurite length. DRG cultures not PMF exposed had a characteristic radial pattern of neurite outgrowth. These results suggest that PMF may offer a noninvasive mechanism to direct and promote nerve regeneration.

A box coil for the stimulation of biological tissue and cells in vitro and in vivo by pulsed magnetic fields.

An alternative coil system to the Helmoholtz coil-pair is described for the stimulation of biological tissue and cells: a relatively large box coil made of copper or aluminum sheet stock. The design is based on the principal determinant of the induced electric field, namely, the magnetic vector potential (A), in the equation, [formula: see text]. The second term in the equation is needed when boundaries of the conducting medium are in close proximity to the region of interest, such as in a culture dish. An electric surface charge builds up on the boundaries to generate an electric field which cancels [formula: see text] at the surface. The effectiveness of the new coil is demonstrated in a study of the outgrowth enhancement of axons from rat embryonic dorsal root ganglia.

Effects of pulsed magnetic fields on neurite outgrowth from chick embryo dorsal root ganglia.

We have previously shown that neurite outgrowth from 6-day chick embryo dorsal root ganglia (DRG) in vitro was stimulated when nerve growth factor (NGF) and pulsed magnetic fields (PMF) are used in combination. 392 DRGs were studied in a field excited by a commercial PMF generator. We have now analyzed an additional 416 DRGs exposed to very similar PMF's produced by an arbitrary wavefrom generator and power amplifier. We reproduced our previous findings that combination of NGF and bursts of asymmetric, 220 microsecond-wide, 4.0 mT-peak pulses induced significantly (p < 0.05) greater outgrowth than NGF alone, that fields without NGF do not significantly alter outgrowth, and that, unlike NGF alone, 4.0 mT fields and NGF can induce asymmetric outgrowth. The asymmetry does not seem to have a preferred orientation with respect to the induced electric field. Analysis of the data for the entire 808 DRGs confirms these findings. Importantly, we find similar results for pulse bursts repeated at 15 or 25 Hz.

Hyposomatomedinemia in quadriplegic men.

Many studies have shown that vigorous exercise acutely stimulates growth hormone (GH) release but the relative contribution of daily physical activity to maintaining the GH/somatomedin C (SmC) axis is not known. It has been reported that basal and post-exercise plasma SmC values are higher in physically conditioned young men than in sedentary men of similar age. To assess the effect of severe inactivity on the plasma SmC level, basal concentrations of this hormone were measured in patients with quadriplegia (QP) resulting from spinal cord injury (SCI). Venous blood samples were obtained after overnight fast in 41 QP men, ages 24-66, and compared with 119 healthy men of similar ages. Nonparametric analysis of variance showed SmC to be significantly lower in QP than in healthy men (p < .007). Plasma SmC below 0.35 U/ml in adults usually indicates little or no GH secretion by the pituitary gland. In QP, 46% of plasma SmC values were < 0.35 U/ml compared to 24% in the healthy group (p < .02). In both groups, an inverse relationship of SmC and increasing age was observed (p < .01). The data suggest that severe inactivity or SCI tend to cause hyposomatomedinemia. The latter endocrine alteration may contribute to the decrease in lean body mass and muscle atrophy of QP patients, and add further functional impairment to the original neurologic deficit. In addition, hyposomatomedinemia could increase the tendency for pressure sore formation and osteoporosis in SCI patients.

Lipid and lipoprotein abnormalities in young quadriplegic men.

To assess the effect of severe inactivity on the serum lipid and lipoprotein profile, 21 quadriplegic men between the ages of 24 and 47 were compared with 20 age-matched healthy control men. The group of quadriplegic men had significantly lower levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), HDL2-C and HDL3-C. The current recommendation for desirable TC is less than 200 mg/dl, whereas HDL-C of less than 35 mg/dl is considered a risk factor for coronary heart disease. Of the 50% (10/20) of the men in the normal control group who had a desirable TC, only 10% (1/10) had a low or undesirable HDL-C value. In comparison, although 81% (17/21) of the group of quadriplegic men had a desirable TC, 53% (9/17) of these individuals had a low HDL-C level. It is concluded that although the presence of lower TC could be beneficial in QM, the decreased values of HDL-C and HDL2-C and the increased ratio of TC/HDL-C suggest a higher risk of coronary heart disease. The findings are consistent with recent reports of an increased prevalence of coronary heart disease in spinal cord injury patients, which could be due to an abnormal lipoprotein profile related to diet, inactivity, changes in body composition, and life style. Moreover, the present data suggest that HDL-C should be measured in quadriplegic men with modifiable risk factors, even if they have desirable TC, to avoid missing an increased coronary heart disease risk status.

Health effects of nonionizing radiation.

Electromagnetic energy in the microwave and radiofrequency bands can produce biologic effects, which are predominantly thermal. During therapeutic use under medical supervision, desired biologic effects are produced and potentially injurious effects minimized. The biologic effects of electromagnetic fields have materialized because of a recent concern that relatively low-level fields produced by everyday electrical appliances, wiring in the home, and power transmission lines may be causally related to a number of detrimental health effects.

Graded spinal cord injuries produced in rabbits with non-invasive microwave hyperthermia.

The use of non-invasive microwave energy to produce spinal cord injuries with intraspinal hyperthermia was studied in experimental animals. Lesions were produced with external beam microwave irradiation at 915 MHz in rabbits, using intraspinal temperature levels from 40 to 43 degrees C., and periods of heating ranging from 15 to 60 minutes. The parameters which determined thermal dose were the degree of temperature elevation in the spinal cord relative to the body core and the duration of that elevation. Thermal dose-response relationships were established by monitoring intraspinal temperatures during heating using an epidural thermistor probe at T8. Animals were examined 48 hours after lesion production and assigned a neurological grade. Injuries were grouped clinically according to their degree of relative functional severity as minimal, mild, moderate, or severe. Evaluation of spinal cord integrity was carried out by recording cortical somatosensory evoked responses (SER) following sciatic nerve stimulation. Increased SER latencies were first observed after heating the spinal cord to 41 degrees for 60 minutes. Impulse transmission was absent after heating to 42 degrees for 30 minutes, a thermal dose which produced complete paraplegia. Morphologically, lesion size and configuration were directly related to the thermal dose used in their production. Low thermal doses produced white matter edema limited to the posterior columns, while larger doses resulted in demyelination, retrograde neuronal changes, and infarction of the dorsal half of the cord. High thermal doses also produced foci of hemorrhage in the gray and white matter of the dorsal cord. These studies suggest that reproducible spinal cord injuries with predictable levels of neurological severity can be produced by noninvasive microwave heating.(ABSTRACT TRUNCATED AT 250 WORDS)

Putrescine as a biochemical marker of malignant brain tumors.

Putrescine, spermidine, and spermine levels were determined in normal brain and central nervous system-related tumor tissues obtained at operation from 50 patients. The biochemical data were correlated with morphological histopathological descriptions of the same tissues. There was little variation in putrescine levels in normal cerebral cortical tissue. Subcortical white matter had lower putrescine but higher spermidine content than those of the overlying cortex. Putrescine levels were elevated in all astrocytomas assayed, and the magnitude of this elevation was proportional to the malignancy of the tumor as determined by histopathological criteria. In contradistinction, putrescine content of "benign" tumors was generally equal to or lower than that of the normal cerebral cortex. Spermidine and spermine levels varied widely in the tumors assayed and did not correlate with criteria of malignancy. It is concluded that putrescine may be a good biochemical marker of malignancy in central nervous system-related tumors.

Treatment of experimental cerebral infarction in rats with levodopa or with glycerol.

Administration of large amounts of levodopa did not improve survival rates of rats after acute cerebral infarction induced by injection of carbon microspheres. However, when 10% glycerol was used, the number of rats that survived after cerebral infarction was significantly greater than in the control or in the levodopa-treated rats. Combination of levodopa and glycerol therapy also significantly improved the survival rate of beneficial effect. Pathological findings (gross or microscopic) indicate striking changes in brain tissue after embolization. Development of brain edema of the infarcted left hemisphere corresponded to the type of treatment and to the length of animal survival. Brain-tissue histology indicates that glycerol-treated animals developed less severe edema and had less tissue disruption than control animals. The results suggest that treatment of edema should be one of the primary steps in therapy after acute cerebral infarction.

Human cadaver femoral head homografts for anterior cervical spine fusions.

Cylindrical, dowel shaped human cadaver bone homografts from the heads of femurs were excised under sterile conditions. Forty-one of these grafts were stored at -80 degrees C and, on thawing, were used in performing anterior cervical spine fusions. Nineteen grafts were freeze-dried, stored at room temperature, reconstituted in saline and used in identical fashion. The use of these grafts, rather than those obtained from the ileum, offered several advantages. The grafts could be cut to a desired length of up to 2.5 cm and were composed of a very dense cancellous bone. Graft collapse and graft extrusion were not encountered.