Early osteolysis with Hylamer acetabular liners.

We reviewed 78 patients with Hylamer acetabular liners (DePuy-Dupont Orthopedics, Warsaw, IN), with a mean follow-up of 3.8 years (range, 2-6 years), for signs of osteolysis secondary to polyethylene wear. Nine patients (11.5%) showed osteolysis greater than 1 cm2. One patient had a greater trochanter fracture through a lytic area, one patient required a revision at 4 years for severe acetabular and femoral lysis with lesser trochanter fracture, and a second patient is awaiting revision.

Heart rate variations during sleep in preadolescents.

Heart rate variations during sleep have been documented for infant and adult populations, but not for children and adolescents. To provide normative data for the preadolescent age group, this investigation used a combination of time-domain measures and nonlinear procedures (Poincare plots) to describe heart rate variations during two consecutive nights of undisturbed baseline sleep in 14 normal 8- to 10-year-old males. Heart rate variables, based on all-night analyses of computer-determined beat-to-beat (RR) intervals, were related to sleep stage and sleep cycle measures within and across nights. Time-domain summary statistics revealed a tendency for higher mean heart rates in rapid eye movement (REM) compared to slow-wave (SW) and stage 2 sleep, but the differences were not significant. Heart rate variability, as measured by average RR interval standard deviation, was greatest in stage 2 and least in SW sleep, but it did not vary significantly across sleep stages. Analyses of heart rate variables across the initial four sleep cycles showed a significant heart rate decrease (quadratic trend) and a significant increase (linear trend) for heart rate variability. All effects replicated across nights. Poincare plots revealed wide-ranging individual differences, generally characterized by greater dispersion at longer RR intervals and a remarkable night-to-night consistency in whole-night as well as stage-specific patterns. The sleep-stage plots uniformly indicated reduced overall range and variability in SW relative to REM and stage 2 and a general equivalence of stage 2 and REM patterns. The results indicate several features of sleep-related heart rate variations in preadolescents that differ from those in adults. The differences can be attributed to developmental variations in autonomic cardiac control and are consistent with increased parasympathetic influences reported to occur at this time.

Effects of hyperglycemia on memory and hormone levels in dementia of the Alzheimer type: a longitudinal study.

The effect of hyperglycemia on hormone levels, metabolite levels, and memory performance was examined in 22 subjects with very mild and mild probable dementia of the Alzheimer type (DAT) and in 12 normal elderly adults. Subjects were tested in 3 plasma glucose conditions (fasting baseline, 175 mg/dl, and 225 mg/dl) at initial and 18-month follow-up sessions. Initially, adults with very mild DAT showed memory facilitation and elevations in plasma insulin in the 225-mg/dl glucose condition relative to baseline. At follow-up, very mild DAT patients whose dementia had progressed showed significant decreases in insulin and hyperglycemic memory facilitation. Changes in basal insulin and cortisol levels over time were correlated with memory changes for DAT subjects. These results suggest that glucoregulatory abnormalities may contribute to the pathophysiology of DAT.

Sequence analyses of herpesviral enzymes suggest an ancient origin for human sexual behavior.

Comparison of the amino acid sequences of the deoxythymidine kinases of herpes simplex (HSV) and of marmoset herpes viruses (MHV) suggests a divergence time of 8 to 10 million years ago for HSV-1 and -2. Like MHV, HSV-1 and -2 cause local infections in their natural hosts, and direct contact between two individuals during the brief period of infectivity is needed for transmission. Because B virus, a nearer relative of HSV, depends on both oral and genital routes of transmission, we postulate that ancestral HSV (aHSV) was similar, and that for HSV-1 and -2 to diverge, genital and oral sites had to become microbiologically somewhat isolated from each other, while oral--oral and genital--genital contact had to be facilitated to maintain both aHSV strains. We propose that acquisition of continual sexual attractiveness by the ancestral human female and the adoption of close face-to-face mating, two hallmarks of human sexual behavior, provided the conditions for the divergence.

Thymine salvage, mitochondria, and the evolution of the herpesviruses.

The salvage of thymine is an apparently ubiquitous feature of free-living lifeforms as well as of mitochondria, chloroplasts and most of the large DNA viruses. Assumptions and data are described which explain the evolution of thymine salvage in prokaryotes, animal cells, and large DNA viruses, in terms of deoxythymidine kinase and its relationship to mitochondria. Specifically, it is suggested that regulation of deoxythymidine kinase (by end-product inhibition) has evolved as a means of assuring a constant supply of thymine compounds for the mitochondria and that the degree to which this regulation is present in the deoxythymidine kinases of the various herpesviruses correlates with the degree of dependence of their replicative cycle on the continued health of the mitochondria of their host cells.

Experimental evaluation of heat and moisture transfer in metal dog cage environments.

Dog cages with solid and expanded metal flooring were tested while unoccupied, occupied by a 10-kg adult male beagle, and occupied by simulated loads to represent a beagle and a greyhound. Cage performances were evaluated with no direct coupling between the room air supply and the cage, and with mechanical coupling of 50% and 100% of the room air supplied directly to the cage. At each of these conditions, the room was maintained at approximately 24 degrees C and 45% relative humidity with room air exchange rates of 5, 10, and 15 changes per hr. Results indicated significant differences existed in dry-bulb and dew-point temperatures between the cage and the room. These differences, together with significant vertical gradients of air velocity and dry-bulb and dew-point temperatures within the cage were shown to be affected by room air exchange rate, cage flooring, type of coupling, and cage load.