Increased expression of peripheral benzodiazepine receptors in the facial nucleus following motor neuron axotomy

Peripheral benzodiazepine receptors (PBRs) are expressed in a variety of tissues but are normally found at low levels in the brain. Following various types of nerve injury, a reactive gliosis results that exhibits a high expression of this receptor. To further characterize the expression of PBRs following neuronal injury, we evaluated PBR expression in the facial nucleus following facial nerve axotomy (FNA). Injury to a peripheral nerve results in a complex series of metabolic and morphological changes around the injured neuron. Transections of the facial nerve results in a rapid activation of both astrocytes and microglia around axotomized motor neurons. FNA resulted in an increase in the staining for both astrocytes (glial fibrillary acidic protein) and activated microglia (OX42). There was also a reduction in synaptic contacts with the motor nucleus as evidenced by reduced staining for the synaptic marker, synaptophysin. In sections labeled with [3H]-PK11195, the subsequent autoradiograms displayed marked increases in the labeling for PBRs. This increase was observed at 5, 7 and 10 days after nerve transection. The increase was primarily in the level of expression (Bmax), with no change in the affinity of the ligand (Kd). The increase in PBR expression after FNA supports the hypothesis that PBRs can be used as a sensitive marker for CNS injury.     

Aesthetic outcome of breast implant removal in 85 consecutive patients

As we began to see increasing numbers of women concerned about their gel-filled breast implants, we became aware that we could not advise them with any degree of confidence what they might expect in terms of aesthetic result after implant removal. We decided to review the records and outcomes over a 2-year period of a number of patients who underwent implant removal. Eighty-five consecutive patients were reviewed, 69 of whom had undergone cosmetic augmentation and 16 of whom had breast reconstruction with silicone gel implant(s). Thirty-nine of the 69 cosmetic augmentation patients had removal of implants alone, and 27 had removal accompanied by mastopexy. Three had reaugmentation with saline-filled implants; one had replacement with saline-filled implants. Fifteen of the 16 reconstruction patients underwent autogenous tissue transfer. Preoperative and postoperative photographs of all patients were mixed randomly and rated by two independent raters in four aesthetic categories on a five-point scoring system. Repeatability was measured several weeks later, when each rater scored randomly selected photographs from this patient pool. The patients also performed their own outcome evaluations by means of questionnaire. We discovered that cosmetic augmentation patients who undergo implant removal only often suffer adverse aesthetic results. The postremoval appearance of many cosmetic augmentation patients actually will be improved over their preoperative appearance when mastopexy is performed in conjunction with implant removal. The study demonstrated that patients with certain body types could expect a particular outcome; i.e., women with asthenic builds and older patients with lax, striated breast skin generally had unsatisfactory aesthetic outcomes with implant removal only. Patients selected for autogenous breast reconstruction had favorable results, with extended latissimus dorsi and TRAM flaps yielding equally good outcomes. The study allows us to offer patients an optimistic view of postoperative results following breast implant removal. We have begun to advise selected patients that implant removal accompanied by mastopexy provides a more pleasing aesthetic outcome than implant removal alone.     

Experimental and theoretical comparison of NIR spectroscopy measurements of cerebral hemoglobin changes

Two near-infrared spectroscopy (NIRS) methods are available for measuring changes (Delta) in total cerebral hemoglobin concentration (CHC): 1) a continuous measurement of the changes in total hemoglobin concentration (Delta[Hb]tot) and 2) the difference between two absolute measurements of CHC, each derived from a small, controlled change in inspired O2 fraction. This paper investigates the internal consistency of these two methods by using an experimental and theoretical comparison. NIRS was used to measure [Hb]tot in five newborn piglets before and after a change in arterial PCO2. Delta[Hb]tot demonstrated a low coefficient of variation of 2.8 +/- 2.8 (SD) % which allowed changes in CO2-cerebral blood volume reactivity to be clearly discriminated. However, a high coefficient of variation of 22.8 +/- 3.5% on the DeltaCHC measurements obscured any CO2 reactivity changes. A theoretical analysis demonstrates the effects of optical pathlength, background absorption, scatter, and blood vessel diameter on both methods. For more accurate monitoring of CHC, individual measurements of optical pathlength and more accurate pulse oximetry are required.     

Quasi-static and dynamic crushing behaviors of aluminum and steel tubes with a cutout

Tubular members are commonly used as an energy absorber in engineering structures and many such members have a cutout. In this study, the crushing behaviors of tubes with a cutout are characterized and the effects of cutout on the energy absorption capabilities of these tubes are quantified. Systematic parametric studies were carried out to study the effect of material properties, including yield and ultimate strength of material, strain rate effect, location of cutout, tube length and impact speed on the crushing behaviors and energy absorption capacity of aluminum and steel tubes. First, a numerical model was constructed with a commercial explicit finite element code. It will be first proven that the numerical simulation can produce sufficiently accurate results in an economic manner. Subsequently, the crushing behavior of aluminum and steel tubes with a cutout was experimentally characterized and their energy absorption capacity was evaluated in terms of mean crushing force, peak crushing force and specific energy absorption (SEA). Tubes of various lengths with a cutout located at different locations, subject to both quasi-static and dynamic impact loadings were considered. For steel tubes, the numerical simulation investigated the influence of the strain rate effect and variation in strain hardening ratio of the material. Empirical equations describing the mean and peak crushing forces of aluminum and steel tubes with a cutout were developed using linear and nonlinear regression methods applied to the results obtained from the numerical and experimental studies.     

Global self-ratings of health and mortality: hazard in the North Carolina Piedmont

We analyzed the first 5 years of surveillance data from the Established Population for the Epidemiologic Studies of the Elderly (EPESE) in the Piedmont of North Carolina (n = 4162) to estimate the effect of a global self-rating of health on survival. Covariates used in Cox proportional hazard models included sociodemographic factors, chronic medical conditions, activities of daily living, use of health services, health risk behaviors, cognitive function, affective mood, and negative life events. Adjusted risk of mortality associated with poor (compared to excellent) self-ratings of health was significantly elevated among urban men only. Confounders of the association between survival and overall health assessment varied widely by subgroup. Pooled estimates from heterogeneous populations may mask significant subgroup differences both in the pattern of variables that mediate crude risk and also in the magnitude of residual risk of global self-ratings of health.     

Antimicrobial effect of combinations of EDTA-Tris and amikacin or neomycin on the microorganisms associated with otitis externa in dogs

Combinations of EDTA-Tris and two aminoglycoside antibiotics (amikacin and neomycin) were tested for synergistic activities against the microorganisms associated with otitis externa in dogs and for the solutions' stability over time. Synergistic activity was observed when EDTA-Tris plus amikacin and EDTA-Tris plus neomycin were tested against Staphylococcus intermedius, Proteus mirabilis, Pseudomonas aeruginosa, and Escherichia coli, but not against Candida albicans. Stability studies over a 3-month period indicated that the test solutions were stable at room temperature and that their antimicrobial activity was maintained.