Mapping the active sites of 3-phosphoglycerate kinase and glycerol kinase with monoammine chromium(III) ATP

The 12 isomers of monoammine chromium(III) ATP have been used to probe the ATP binding sites of yeast 3-phosphoglycerate kinase and glycerol kinase from Candida mycoderma. Inhibition studies of 3-phosphoglycerate kinase show a dramatic decrease in isomer binding only when the ammonia is in the Delta axial facial anti position. This suggests an open site architecture with only one strong contact point between the coordination sphere and the enzyme surface. These results agree well with the computer modeling studies of bidentate chromium ATP into the nucleotide site determined by X-ray crystallography [McPhillips, T., et al. (1996) Biochemistry 35, 4118-4127]. Both methods describe an open site strongly supporting the validity of the inhibition studies. Inhibition studies of glycerol kinase show significant decreases in binding for all the tested ammonia positions, suggesting a closed site architecture with many contacts between the coordination sphere and the surface of the enzyme. This is in good agreement with X-ray studies [Hurley, T., et al. (1993) Science 259, 673-677] on the Escherichia coli glycerol kinase. Inhibition studies of hexokinase previously reported [Rawlings, J., et al. (1993) Biochemistry 32, 11204-11210] more closely resemble those of 3-phosphoglycerate kinase, suggesting the surprising result that however closely hexokinase and glycerol kinase are related structurally the site around the coordination sphere in hexokinase is functionally open like that of 3-phosphoglycerate kinase.     

Is homophobia associated with homosexual arousal?

The authors investigated the role of homosexual arousal in exclusively heterosexual men who admitted negative affect toward homosexual individuals. Participants consisted of a group of homophobic men (n?=?35 ) and a group of nonhomophobic men (n?=?29); they were assigned to groups on the basis of their scores on the Index of Homophobia (W. W. Hudson & W. A. Ricketts, 1980). The men were exposed to sexually explicit erotic stimuli consisting of heterosexual, male homosexual, and lesbian videotapes, and changes in penile circumference were monitored. They also completed an Aggression Questionnaire (A. H. Buss & M. Perry, 1992). Both groups exhibited increases in penile circumference to the heterosexual and female homosexual videos. Only the homophobic men showed an increase in penile erection to male homosexual stimuli. The groups did not differ in aggression. Homophobia is apparently associated with homosexual arousal that the homophobic individual is either unaware of or denies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasonic crack characterization via a constrained inversion algorithm

The Kirchhoff approximation is used to show that the time domain impulse response of an isolated flat crack can be given a simple geometrical interpretation in terms of the derivative of a projected length function. For an elliptical crack, this derivative can be obtained explicitly to yield the two edge-diffracted waves which originate from the flashpoints of the crack. An explicit coordinate invariant expression is obtained from this elliptical crack solution which relates the time difference, t, between the arrival of these edge-diffracted waves and the crack size and orientation. Previously, we have proposed that this expression, together with t measurements in different scattering directions, could be used in a regression analysis as the basis for performing a constrained inversion of crack scattering data (i.e., where we attempt to obtain the best equivalent flat elliptical crack that fits the scattering measurements). Here we will demonstrate some results of applying the proposed algorithm using noisy synthetic data. The sensitivity of the results to both, number of measurements and transducer orientation, will be discussed.     

Epidemiology of toxic shock syndrome toxin-1 production in Staphylococcus aureus strains isolated in Denmark between 1959 and 1990

A total of 436 Staphylococcus aureus bacteremia strains isolated between 1959 and 1990 were tested for the production of toxic shock syndrome toxin-1 (TSST-1) by a semiquantitative reversed passive latex agglutination test. TSST-1 production was found in 147/260 (57%) of phage group I strains, excluding the "80" complex, and in 17/176 (10%) of non-group I strains. Strains of the 52, 52A, 80, 81 complex ("80" complex), constituting a subgroup of group I, did not have the same high frequency of TSST-1 production as the rest of group I strains (4% versus 57%). The "80" complex has almost disappeared in Denmark. TSST-1 production was found with the same high frequency among group I strains from the beginning (1959) and throughout the observation period. The TSST-1 production was associated with the phages 29 and/or 52, which in turn lysed 95% of group I strains. The TSST-1 production was quantitatively greater in the phage group I strains than in the non-group I strains. TSST-1 production of the bacteremia strains was not correlated to the clinical parameters: mortality, age, gender, bacterial focus, underlying diseases, or whether the infection was hospital or community acquired.     

High resolution ultrastructural mapping of total calcium: electron spectroscopic imaging/electron energy loss spectroscopy analysis of a physically/chemically processed nerve-muscle preparation

We report on a procedure for tissue preparation that combines thoroughly controlled physical and chemical treatments: quick-freezing and freeze-drying followed by fixation with OsO4 vapors and embedding by direct resin infiltration. Specimens of frog cutaneous pectoris muscle thus prepared were analyzed for total calcium using electron spectroscopic imaging/electron energy loss spectroscopy (ESI/EELS) approach. The preservation of the ultrastructure was excellent, with positive K/Na ratios revealed in the fibers by x-ray microanalysis. Clear, high-resolution EELS/ESI calcium signals were recorded from the lumen of terminal cisternae of the sarcoplasmic reticulum but not from longitudinal cisternae, as expected from previous studies carried out with different techniques. In many mitochondria, calcium was below detection whereas in others it was appreciable although at variable level. Within the motor nerve terminals, synaptic vesicles as well as some cisternae of the smooth endoplasmic reticulum yielded positive signals at variance with mitochondria, that were most often below detection. Taken as a whole, the present study reveals the potential of our experimental approach to map with high spatial resolution the total calcium within individual intracellular organelles identified by their established ultrastructure, but only where the element is present at high levels.     

Impending malunions of the hand. Treatment of subacute, malaligned fractures

Malunions of the hand present a challenging problem to the orthopaedic surgeon. Angular and rotational deformities, and shortening and articular incongruity, can lead to significant functional impairment or dysesthetic appearance. The prevention of malunion should remain a primary goal. When displaced fractures of the metacarpals or phalanges present within the first or second weeks, properly performed closed or open reduction with percutaneous pinning or internal fixation are excellent options with predictable results. Malaligned fractures that present later frequently cannot be readily reduced. Once fully united, treatment options have included corrective osteotomy if function is significantly impaired or if appearance is objectionable; for patients who are not suitable for surgery for medical or other reasons, or for whom appearance is acceptable, intensive occupational therapy to maximize function may yield sufficiently serviceable clinical results. During the past several years, the senior author (BL) has chosen to be more proactive in the prevention of malunions of the hand. In the authors' experience, results of aggressive surgical treatment of subacute, malaligned fractures in selected patients have produced results comparable with or superior to those reported for later reconstructive procedures. With the proliferation of managed care, there has been an increasing frequency of delayed referral patterns for fracture treatment by hand specialists. Definitive treatment of these "impending malunions" is preferable to passive treatment delay and secondary reconstructive procedures, offering both earlier correction of alignment and earlier opportunity for return of function.     

Adolescent Adjustment Before and After HIV-Related Parental Death.

The impact of HIV-related parental death on 414 adolescents was examined over a period of 6 years. The adjustment of bereaved adolescents was compared over 4 time periods relative to parental death and was also compared with the adjustment of nonbereaved adolescents. Bereaved adolescents had significantly more emotional distress, negative life events, and contact with the criminal justice system than nonbereaved youths; these behaviors did not remain significantly higher after parental death. Depressive symptoms and passive problem solving increased soon after parental death, as compared with nonbereaved adolescents. One year subsequent to parental death, depression and passive problem solving were similar to the levels of nonbereaved peers. Only sexual risk behaviors increased following parental death. These results suggest the importance of early family intervention soon after parental HIV diagnosis, prior to parental death, and sustained over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developing an Automated Enzyme Immunoassay for High-Throughput Screening of Bovine Serum Antibodies to Neospora Caninum

An enzyme-linked immunosorbent assay (ELISA) for Neospora caninum antibodies was automated with a robotic workstation, the Beckman Coulter Biomek 2000, to screen 200 bovine sera. Comparing these results with manually run ELISA data, a 95.92% agreement (K = 0.9592) between the two assays was obtained. The automated assay was specific and sensitive with excellent positive and negative predictive values. The results were repeatable and reproducible. The automation flexibility was high and the operation complexity was minimal. High-throughput screening (HTS) for bovine antibodies to Neospora caninum was achieved. The assay was developed according to the internationally recognized ISO17025 standard requirements.     

Modeling Ultrasonic Pulse-Echo Signals from a Flat-Bottom Hole in Immersion Testing Using a Multi-Gaussian Beam

This paper proposes an ultrasonic measurement model that can predict the pulse-echo signals from a flat-bottom hole in an isotropic, homogeneous solid specimen immersed in water in a computationally efficient manner. To develop such a model, a measurement model approach is adopted based on two important assumptions: the paraxial approximation for the transducer beam and the small flaw assumption for the flat-bottom hole. The modular model that results from these two assumptions contains three terms: a diffraction correction term, a far-field scattering amplitude term and a system efficiency factor term. The diffraction correction is defined based on a multi-Gaussian beam model which allows the rapid evaluation of the wave field incident on the hole. The far-field scattering amplitude of the flat-bottom hole is obtained using the Kirchhoff approximation together with the small flaw assumption. The system efficiency factor is determined by deconvolution of an experimental front surface reflection signal by a reference reflector model. Here, the contribution of each of these three terms to the overall measurement model are described in detail and the accuracy of the proposed model is verified by the comparison of the model-based predictions to experiments.     

Order vs. Disorder: Cholesterol and Omega-3 Phospholipids Determine Biomembrane Organization

Lipid structural diversity strongly affects biomembrane chemico-physical and structural properties in addition to membrane-associated events. At high concentrations, cholesterol increases membrane order and rigidity, while polyunsaturated lipids are reported to increase disorder and flexibility. How these different tendencies balance in composite bilayers is still controversial. In this study, electron paramagnetic resonance spectroscopy, small angle neutron scattering, and neutron reflectivity were used to investigate the structural properties of cholesterol-containing lipid bilayers in the fluid state with increasing amounts of polyunsaturated omega-3 lipids. Either the hybrid 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine or the symmetric 1,2-docosahexaenoyl-sn-glycero-3-phosphocholine were added to the mixture of the naturally abundant 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and cholesterol. Our results indicate that the hybrid and the symmetric omega-3 phospholipids affect the microscopic organization of lipid bilayers differently. Cholesterol does not segregate from polyunsaturated phospholipids and, through interactions with them, is able to suppress the formation of non-lamellar structures induced by the symmetric polyunsaturated lipid. However, this order/disorder balance leads to a bilayer whose structural organization cannot be ascribed to either a liquid ordered or to a canonical liquid disordered phase, in that it displays a very loose packing of the intermediate segments of lipid chains.