Clinical measures of balance and gait cannot differentiate somatosensory impairments in people with lower-limb amputation.

BACKGROUND: In addition to a range of functional impairments seen in individuals with a lower-limb amputation, this population is at a substantially elevated risk of falls. Studies postulate that the lack of sensory feedback from the prosthetic limb contributes heavily to these impairments, but the extent to which sensation affects functional measures remains unclear. RESEARCH QUESTION: The purpose of this study is to determine how sensory impairments in the lower extremities relate to performance with common clinical functional measures of balance and gait in individuals with a lower-limb amputation. Here we evaluate the effects of somatosensory integrity to clinical and lab measures of static, reactive and dynamic balance, and gait stability. METHODS: In 20 individuals with lower-limb amputation (AMP) and 20 age and gender-matched able-bodied controls (CON), we evaluated the effects of sensory integrity (pressure, proprioception, and vibration) on measures of balance and gait. Static, reactive, and dynamic balance were assessed using the Sensory Organization Test (SOT), Motor Control Test (MCT), and Functional Gait Assessment (FGA), respectively. Gait stability was assessed through measures of step length asymmetry and step width variability. Sensation was categorized into intact or impaired sensation by pressure thresholds and differences across groups were analyzed. RESULTS: There were significant differences between AMP and CON groups for reliance on vision for static balance in the SOT, MCT, and FGA (p < 0.01). Despite differences across groups, there were no significant differences within the AMP group based on intact or impaired sensation across all functional measures. SIGNIFICANCE: Despite being able to detect differences between able-bodied individuals and individuals with an amputation, these functional measures cannot distinguish between levels of impairment within participants with an amputation. These findings suggest that more challenging and robust metrics are needed to evaluate the effects of sensation and function in individuals with an amputation.

Including sheath effects in the interpretation of planar retarding potential analyzer's low-energy ion data.

The interpretation of planar retarding potential analyzers (RPA) during ionospheric sounding rocket missions requires modeling the thick 3D plasma sheath. This paper overviews the theory of RPAs with an emphasis placed on the impact of the sheath on current-voltage (I-V) curves. It then describes the Petite Ion Probe (PIP) which has been designed to function in this difficult regime. The data analysis procedure for this instrument is discussed in detail. Data analysis begins by modeling the sheath with the Spacecraft Plasma Interaction System (SPIS), a particle-in-cell code. Test particles are traced through the sheath and detector to determine the detector's response. A training set is constructed from these simulated curves for a support vector regression analysis which relates the properties of the I-V curve to the properties of the plasma. The first in situ use of the PIPs occurred during the MICA sounding rocket mission which launched from Poker Flat, Alaska in February of 2012. These data are presented as a case study, providing valuable cross-instrument comparisons. A heritage top-hat thermal ion electrostatic analyzer, called the HT, and a multi-needle Langmuir probe have been used to validate both the PIPs and the data analysis method. Compared to the HT, the PIP ion temperature measurements agree with a root-mean-square error of 0.023 eV. These two instruments agree on the parallel-to-B plasma flow velocity with a root-mean-square error of 130 m/s. The PIP with its field of view aligned perpendicular-to-B provided a density measurement with an 11% error compared to the multi-needle Langmuir Probe. Higher error in the other PIP's density measurement is likely due to simplifications in the SPIS model geometry.

Partial characterization and proposed mode of action of inhibitory HeLa cell surface polypeptides.

Polypeptides removed from the HeLa cell surface by mild pronase treatment rapidly inhibit protein synthesis when added to HeLa cells or cell-free translation systems derived from HeLa cells. The inhibitory activity is heat stable. Protein and carbohydrate components of these polypeptides are required for inhibition of protein synthesis in vivo and in vitro. Two peaks of activity can be recovered from polyacrylamide gels, corresponding to polypeptides with molecular weights of approximately 29 000 and 41 000. Inhibition of protein synthesis in cell-free translation systems appears to be primarily an effect on elongation of polypeptide chains, whereas in the intact cell the primary target may be polypeptide chain initiation.

Detergents modulate dimerization, but not helicity, of the glycophorin A transmembrane domain.

Understanding how the lipid environment influences transmembrane helix association requires thermodynamic measurements that can be interpreted in terms of specific chemical interactions. We have used Förster resonance energy transfer to measure dimerization of the glycophorin A transmembrane helix in detergent micelles. The observed Kd is at least two orders of magnitude weaker in sodium dodecyl sulfate than it is in zwitterionic detergents. In contrast, neither dimerization nor the detergent affects the secondary structure of the glycophorin A helix as measured by far-UV circular dichroism. These measurements support a long standing assumption about the glycophorin A transmembrane domain, that detergents uncouple helix formation from helix dimerization. The approach is applicable to a variety of systems in diverse environments, extending our ability to measure how interactions with complex solvents affect the thermodynamics of oligomerization.

Effect of chronic administration of estrogen, androgen, or both on serum levels of gonadotropins in adult men.

Ethinyl estradiol (50 micrograms/day) or fluoxymesterone (10 or 20 mg/day), chosen because each is orally active and because fluoxymesterone is probably not converted to an estrogen, were given alone and in combination to adult men over several weeks. Measurements were made of serum FSH, LH, testosterone, and estradiol. The estrogen given alone suppressed serum FSH while the androgen given alone did not; however, the androgen may have enhanced the suppressive effect of the estrogen on the serum FSH. Neither steroid alone changed the serum LH but both together suppressed it. The estrogen alone decreased the serum testosterone, an effect probably mediated by the concomitant fall in serum FSH and a resulting decrease in sensitivity to the constant level of LH; a direct effect of estrogen on the testis seems less likely. The doses of estrogen and androgen used probably had a biologic effect equal to or somewhat above that of endogenously produced estrogen and androgen and thus reflected the maximum physiological effects of the endogenous steroids. Thus, in the chronic physiological control of FSH and LH in adult men, these data indicate that (1) testosterone alone, as an androgen, has little effect on FSH or LH, (2) estradiol (or total estrogen) has a greater suppressive effect on FSH than on LH and by its effect on FSH may indirectly regulate the secretion of testosterone, and (3) testosterone and estradiol together may be involved in the regulation of both FSH and LH.

Pharmacokinetics and pharmacodynamics of methylprednisolone when administered at 8 am versus 4 pm.

The temporal variations in the pharmacokinetics and pharmacodynamics of methylprednisolone at 8 AM versus 4 PM were investigated in six healthy male volunteers. Subjects completed three phases: no drug administration, 20 mg intravenous methylprednisolone at 8 AM, and the same dose at 4 PM. Methylprednisolone clearance was 28% greater in the afternoon. The suppressive effects of methylprednisolone on basophils (measured as whole blood histamine), helper T lymphocytes, and cortisol concentrations, assessed by the ratio of the area under the curve (AUC) after methylprednisolone to the baseline AUC, were not different between the phases. The 50% inhibitory concentration values for methylprednisolone derived from pharmacodynamic models were also similar, indicating no difference in intrinsic responsiveness. However, cortisol concentrations returned to baseline about 4 hours earlier after the 4 PM compared with the 8 AM dose because of the enhanced afternoon methylprednisolone clearance. These findings are in agreement with other studies that suggest adequate clinical effects and less disturbance of cortisol circadian behavior when methylprednisolone is administered as a single dose in the morning.

Cerebral mucormycosis: an unusual case.

A 36-year-old obese woman with hyperglycemia and immunosuppression died of bilateral internal carotid artery occlusion associated with mucormycosis. This report describes a rare case in which cerebral mucormycosis occurred without the usual preceding clinical evidence of nasal and orbital infection.

1,9-Alkano-bridged 2,3,4,5-tetrahydro-1H-3-benzazepines with affinity for the alpha 2-adrenoceptor and the 5-HT1A receptor.

A number of 1,9-alkano-bridged 2,3,4,5-tetrahydro-1H-3-benzazepines were prepared and evaluated for 5-HT1A receptor and alpha 2-adrenoceptor affinity by using radioligand receptor binding techniques. Several compounds displayed 5-HT1A receptor affinity comparable to, or greater than, the known 5-HT1A ligand buspirone. The highest affinity 5-HT1A receptor ligands were N-alkyl-, N-allyl-5-chloro-, and 5-methoxy-1,2,3,4,8,9,10,10a-octahydronaphth[1,8-cd]azapines (4c, 4m, 4n), which had pKi values of 7.9-8.1. The S enantiomer of 4c had a higher affinity for the 5-HT1A receptor than the corresponding R isomer (pKi of 8.2 for (S)-4c vs 7.7 for (R)-4c). These compounds had a relatively low affinity for the alpha 2-adrenoceptor (pKi of 7 or less). On the other hand, the closely related 5-chloro-2-methyl-2,3,4,8,9,9a-hexahydro-1H-indeno[1,7-cd]azepine (3b) had high affinity for both the alpha 2-adrenoceptor (pKi = 8.1) and 5-HT1A receptor (pKi = 7.6). These results indicate that the two receptors may share common recognition sites.

Pentoxifylline rescue preserves lung function in isolated canine lungs injured with phorbol myristate acetate.

OBJECTIVE: We hypothesized that pentoxifylline, administered after phorbol myristate acetate (PMA), would diminish the severity of lung injury. SETTING: Animal research laboratory. DESIGN: Comparative study. SUBJECTS: Mongrel dogs (n = 33). INTERVENTIONS: Baseline measurements were obtained from the isolated blood-perfused dog lung lobes after 1 h of stable perfusion and ventilation. Four different measures of lung compliance were obtained along with WBC and neutrophil counts. Pulmonary vascular resistance (PVR) and capillary filtration coefficient (Kf) were calculated, and the ratio of a normalized maximal enzymatic conversion rate to the Michaelis-Menten constant (Amax/Km) was used to assess perfused capillary surface area. The control lobes (n = 8) were ventilated and perfused for an additional 40 min while the injured lobes (n = 17) received PMA (0.1 microg/mL of perfusate). The pentoxifylline-protected lobes (n = 8) were treated with pentoxifylline (1 mg/mL of perfusate) 10 min after injury with PMA. All measurements were then repeated. MEASUREMENT AND MAIN RESULTS: The three groups did not differ significantly at baseline. The control lobes remained relatively stable over time. The injured lobes demonstrated marked deterioration in compliance: 8.79 +/- 0.7 to 5.97 +/- 0.59 mL/cm H(2)O (p < 0.05) vs 10.1 +/- 1.0 to 8.07 +/- 0.72 mL/cm H(2)O and 9.6 +/- 1.1 to 9.9 +/- 0.85 mL/cm H(2)O in the control and protected lobes, respectively. Both groups receiving PMA had similar drops in WBC and neutrophil counts, but the pentoxifylline-protected lobes had preservation of all four compliance measures. PVR increased from 37.8 +/- 1.8 to 118.6 +/- 12.7 cm H(2)O/L/min (p < 0.05) in the injured lobes vs 35.4 +/- 0.5 to 36.3 +/- 2.8 cm H(2)O/L/min and 40.4 +/- 0.04 to 46.7 +/- 2.8 cm H(2)O/L/min (p < 0.05) in the control and protected lobes, respectively. Kf increased < 25% in the protected group but more than tripled in the injured group. Amax/Km dropped from 559 +/- 36 to 441 +/- 33 mL/min (p < 0.05) in the injured lobes vs 507 +/- 14 to 490 +/- 17 mL/min and 609 +/- 34 to 616 +/- 37 mL/min in the control and pentoxifylline-protected lobes, respectively. CONCLUSIONS: The use of pentoxifylline as a rescue agent prevented the PMA-induced deterioration of lung compliance, vascular integrity, and endothelial metabolic function in this acute lung injury model, despite significant pulmonary neutrophil sequestration.

The isolation and characterization of milleri group streptococci from dental periapical abscesses.

Reports of the isolation of streptococci from dental abscesses have shown an association of the "S. milleri" group with such lesions. There has been considerable confusion regarding the taxonomy of these organisms, but the milleri group has recently been reclassified into three distinct species: Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius. In this study, 45 samples from dental periapical abscesses were examined. Milleri group streptococci were isolated from 16 patients (37%), 15 being identified as S. anginosus and one as S. intermedius. In one patient, S. anginosus was isolated in pure culture, and it would appear that this is the predominant species of milleri group streptococci associated with periapical abscesses.