Fourth national pressure ulcer prevalence survey.

The fourth national pressure ulcer prevalence survey was conducted on November 9, 1995, with stuff at 265 acute-care hospitals surveying 39,874 patients for the presence of pressure ulcers. Data were collected on patient demographics, ulcer site, ulcer stage, and support surface. The goal was to determine the aggregate prevalence of pressure ulcers and to compare the results to those of the previous three surveys. The overall prevalence was 10.1% (range 1.4% to 36.4%), with the sacrum and heels the most common pressure ulcer sites. The predominant age group of patients with pressure ulcers was 71 to 80 years. Seventy-four percent of pressure ulcers were superficial (i.e., Stages I and II). The national pressure ulcer prevalence has remained relatively constant throughout the four surveys, despite the many changes in health care over the past 7 years.

Measurement of support surface efficacy: pressure.

Two methods can be used to assess the relative pressure-relieving/pressure-reducing effects of clinical support surfaces. The interaction occurring at the interface between the human body and the support surface--known as the interface pressure--can be measured with an interface pressure system. Reactive hyperemia, the physiologic response to pressure, can be measured with thermography and laser Doppler flowmetry. Using mannequins and human subjects that represent typical body types in the older population, a protocol was developed for collecting data on the effects of support surfaces on interface pressure and reactive hyperemia.

Skin vascular reaction to short durations of normal seating.

The effects of duration and compliance of seating surfaces on reactive hyperemia within the skin overlying the ischial tuberosities was determined in four normal, one paraplegic and one cerebral palsy subject. Reactive hyperemia was demonstrated thermographically after short durations (ie, 5, 10, and 15 minutes) of seating on a hard surface. The magnitude of hyperemic response increased significantly (p < .001 for 15 v 5 minutes; p = .019 for 15 v 10 minutes; p = .001 for 10 v 5 minutes) with increased duration of seating. In all six subjects studied, the maximum postseating blood flow continued to increase with up to 15-minute seating on a hard surface, and the mean maximum response was positively correlated with duration of seating (4 = 0.918, p < 0.001). Although there was good correlations between magnitudes of interface pressures measured and vascular responses within each individual, there was no such direct correlation between individuals.

Skin vascular reaction to standard patient positioning on a hospital mattress.

The effects of duration and posture on reactive hyperemia in the skin overlying the greater trochanter of the femur was determined in normal subjects using thermography. Multivariate analysis revealed that in the six subjects studied, post-lying blood flow within the skin superficial to bony prominences was significantly increased over that of the preexperimental and passively-warmed controls. These analyses also showed that both maximal interface pressures and vascular reactions were experienced in the side-lying position when the legs were extended, and significantly reduced when the legs were flexed. While there was good correlation between magnitudes of interface pressures measured and vascular responses within each individual, there was no such direct correlation between individuals. The individual with the highest interface pressures did not have the most intense reactive hyperemic reactions, and the individual with the least interface pressures did not have the least intense reactive hyperemic reactions. Intrinsic features of each individual's vascular response to the normal mechanical forces experienced during lying appear to be a sensitive measure of the individual's susceptibility to develop pressure ulcers.

Developmental neuron cell death in dystrophic and normal chickens.

The numbers of motoneurons in the brachial lateral motor columns were determined from the 6th embryonic day through the 5th week posthatching in age-matched dystrophic and normal chickens. The overall magnitude of cell loss was not significantly different between the dystrophic and normal strains. However there was a trend toward more motoneurons in the brachial lateral motor columns of dystrophic embryos and posthatch chickens which was found to be statistically significant at the 8th and 9th days of embryonic life. These observations are taken to suggest that, in addition to strain differences unrelated to the dystrophic gene, there may exist a temporal delay in developmental neuron cell death in dystrophic chick embryos that may be secondary to the primary defect within the dystrophic muscle.

Structural alterations to Proteus mirabilis as a result of exposure to haemolymph from the larvae of Galleria mellonella.

Scanning and transmission electron microscopy was used to examine Proteus mirabilis, strain 11-1A, for morphologic alterations following exposure to normal and immune cell-free haemolymph obtained from Galleria mellonella larvae. It was found that both normal and immune haemolymph exerted effects on the bacterial cells, with immune haemolymph affecting a much higher percentage of cells than normal haemolymph. The morphological damage observed by scanning electron microscopy (SEM) included abnormal shapes, blebbing of the cell wall, surface erosion and lysis of the cell. Transmission electron microscopy showed evidence of damage to the cell wall and supported the results obtained from SEM.

Variation between homologues and sister chromatids in individual karyotypes.

Chromatid absolute length and density profile from electron micrograph images of human group A chromosomes were studied in an attempt to identify significant individual karyotypic variation. The variation within sister chromatids can be utilized as an internal standard to establish a limit of variability for the purpose of demonstrating differences between homologues. Homologous chromosomes were found to differ with respect to absolute length and density profile.

Image analysis of the acetic acid-alcohol fixed metaphase chromosome.

Electron micrographs of acetic acid-alcohol fixed, unstained human metaphase chromosomes have been analyzed with an image system. Electron micrographs were first digitized from over a million picture elements into a range of 64 gray levels which correspond to mass distribution. The obtained numerical data were then processed by programs which increased contrast and permitted enhancement and expansion of the original image. Despite the disruptive nature of such preparations, analysis of their TEM images reveals structural features previously reported from other preparative methods as well as morphological properties previously reported in metaphase chromosomes which required special pretreatments and staining for demonstration. Familial features included low density centromeres and secondary constrictions, higher density telomeres and paracentromeric regions, and G-band-like differential densities along chromatids. In addition, structural components were observed in a size range 25-56 nm. These masses appeared to have linear and circular forms oriented in perpendicular, diagonal and longitudinal arrays. They appeared in a nonrandom fashion and can be interpreted as demonstrating a relatively ordered chromosome.

Spirals and G-bands as a function of chromosome length.

The quantitative relationship between spirals and G-bands with regard to length has been investigated. Graphical analysis of sub-chromatid structure showed that the numbers of spirals and G-bands are directly proportional to chromosome length. Equations are derived which predict the number of G-bands or gyri appearing based on chromosome length. The width of chromatids was not found to increase proportionately in shorter chromatids. Calculations indicated that the major events occurring during chromosome contraction in metaphase are the shortening of the chromonemata, reduction in numbers of gyri and a slight reduction in unit gyrus length.

Improved sectioning and Berlin blue staining of whole human brain.

Brain sectioning has been improved through gelatin embedding so that more than forty precisely oriented serial sections can be obtained from a single brain. Since the embedding gelatin requires no fixation, it can be removed from the sections prior to staining by simple warming. The reduction of Berlin blue dye commonly observed after staining by the Mulligan method has been found to be at least partly due to light in the UV to near UV range. Dye reduction is significantly inhibited by postfixation in 25% acetic acid.

Effects of acetic acid-alcohol, trypsin, histone 1 and histone fragments on Giemsa staining patterns in chromosomes.

In an effort to minimize subjective bias, a classification scheme was devised to assess Giemsa staining patterns obtained with experiments involving acetic acid-alcohol and exogenously applied histone 1 and polypeptides. A single rinse of metaphase preparations with acetic acid-alcohol quantitatively reduced Giemsa dye binding. Acid-alcohol irreversibly changed the conformation of H1 and its ability to interfere with trypsin G-banding. Our results suggest that, in addition to protein extraction, acid-alcohol may alter the conformation of acid-insoluble components of metaphase chromosomes. The carboxy-terminal polypeptide (residues 73--212) from NBS cleavage of H1 was an effective inhibitor of Giemsa staining and trypsin G-banding. However, this polypeptide which is preferential for supercoiled DNA was much less efficient in inhibiting Giemsa staining of trypsinized metaphase chromosomes. The molecular consequences of these experiments are discussed.