The nursing concept as a basis for the practice of care

OBJECTIVE: To determine the relation between the initial neonatal nucleated erythrocyte (nRBC) count and acute infection or ischemia in cases delivered before 32 weeks' gestation. METHODS: A set of 465 nonanomalous singleton live births delivered at 22-32 weeks' gestational age (GA) contained 386 cases with a complete blood count obtained by 3 hours of life, including 173 cases of premature rupture of the membranes (PROM) before labor, 143 cases of preterm labor with intact membranes (PTL), and 70 cases of preeclampsia. Maternal and neonatal charts were reviewed. Placental histopathology was scored in the following five categories: acute intrauterine inflammation, uteroplacental vascular lesions, intraplacental vaso-occlusive lesions, chronic inflammation, and coagulation-related lesions. The initial nRBC count (nRBCs/100 white blood cells [WBC] x WBC count/dL) was analyzed. RESULTS: In PROM and PTL (controlling for GA), the nRBC count was directly related to the maternal WBC count (PTLP = .018), maternal temperature within 24 hours of delivery (PROM P = .014), initial neonatal WBC count (PROM P < .0001; PTL P = .0004), total myeloid elements (PROM P = .005, PTL P = .009), total nonmyeloid elements (PROM P < .0004, PTL P < .0001), and total placental acute inflammatory score (PROM P = .04, PTL P = .02). In preeclampsia, cytotrophoblast proliferation (P = .02), villous edema (P = .008), "hemorrhagic endovasculitis" (P = .04), and histologic abruption (P = .0006) were directly related to the nRBC count. In well-grown, nonacidotic, nondepressed preterm infants, the nRBC count was independent of gestational age, with the 90th percentile at 5229 nRBC/dL. CONCLUSION: When preterm PROM and PTL are accompanied by acute ascending infection, nRBC release may be a fetal response to the inflamed environment. In preterm preeclampsia, nRBC elevation marks uteroplacental hypoperfusion.     

Correction for photon attenuation in SPECT: analytical framework, average attenuation factors, and a new hybrid approach

We provide a unified framework for the investigation of convergence properties of the iterative algorithms for photon attenuation correction in SPECT, including the iterative Chang method--a commonly used approach in which an average attenuation factor calculated over all projection angles is employed in a pointwise correction scheme. A new average attenuation factor calculated along the projection line is introduced, which can compensate exactly for the attenuation effect in the case of a uniform activity distribution. We propose a new hybrid approach in which we use this new average attenuation factor initially and then shift to the iterative Chang method in later iterations. This hybrid approach was evaluated in a simulation study by use of a computer-generated phantom with both non-uniform activity and non-uniform attenuation distributions. The results demonstrate that this hybrid approach improves the convergence speed of the iterative Chang method and produces reconstructed images of high quality.     

A new approach for the calculation of photon dose conversion factors in the PMMA slab phantom

A new simple method using the computer code MCNP is proposed for calculation of photon dose conversion factors in the PMMA slab phantom. Absorbed dose is calculated by multiplying fluence buildup in the PMMA slab phantom by virtual energy deposition in the ICRU tissue substance. This method does not need auxiliary calculations to determine the dose conversion factors, such as calculation of backscatter factors in the ICRU tissue cube and the PMMA slab phantoms. The discrepancies between the results of the direct method presented here and a more conventional indirect method is less than 2%, except for low energy photons (<100 keV) at large depths. As the direct method reduces the number of calculational steps, the results are more reliable than those of the indirect method.     

The inertia tensor as a basis for the perception of limb orientation.

The ability of humans to perceive the spatial orientation of an occluded arm was investigated. It was hypothesized that this ability is tied to the arm's inertial eigenvectors, invariant mechanical parameters corresponding to a limb's axes of rotational symmetry. By breaking the coincidence between the eigenvectors of the arm and its longitudinal axis, 3 experiments were directed at the possibility that the perceived orientation of an occluded arm would vary as a function of the eigenvectors. Overall, the angles in which the arm was positioned were affected by the direction in which the eigenvectors of the limb were oriented by small appended masses. Discussion focused on the importance of physical invariants for proprioception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic basis of attenuation of the Sabin oral poliovirus vaccines

Four cases of synovial sarcoma with extensive calcification and osteoid and bone formation are reported. Ages ranged from 21 to 38 years. Two tumors were located in the foot and two in the thigh. Because of a well-circumscribed, densely calcified soft tissue mass, radiologically three patients were thought to have a benign lesion. The fourth patient was thought to have a paraosteal osteosarcoma because of an accompanying bone defect. Tumor size varied from 4.0 to 9.0 cm. Histologically, three tumors were biphasic and one predominantly monophasic. All showed amorphous calcifications with extensive ossification sometimes in a ribbon-like pattern of osteoid, simulating osteosarcoma. The extensive bone formation with abundant osteoid deposition may lead to a misdiagnosis of osteosarcoma. It is important to recognize this variant of synovial sarcoma with ossification and bone formation and distinguish it from extraskeletal osteosarcoma because of the difference in clinical behavior and course. Although the most important point in the recognition of this variant of synovial sarcoma is its biphasic pattern, this may not be apparent in a small tissue sample. Points that aid in the diagnosis include the uniform nuclear appearance of both the epithelial and the spindle cells versus the pleomorphism of osteosarcoma and in some cases the presence of amorphous concretions in sheets and small calcospherites within spaces surrounded by flat or conspicuous epithelial cells. These cells are immunoreactive for cytokeratin and epithelial membrane antigen.     

The metabolisable energy as a basis for standardisation of energetic feed evaluation

The advantages and disadvantages of metabolisable and net energy as parameters of energetic feed evaluation are discussed. For a global comprehensive standardisation of the energetic feed evaluation, the metabolisable energy (ME) will have a preference. The principles of an energetic feed evaluation system with ME as parameter are explained according to which the subsystems for all species of animals should be worked out uniformly. The subsystems for the most important farm animals integrate themselves in addition to ME for predicting the energy and food needs of the animal also the net energy (NE) by taking a standard feedstuff to characterise the relative energetic feed value of the feedstuffs for one or more partial performances of the animal species concerned.     

Theoretical and experimental determination of phantom scatter factors for photon fields with different radial energy variation

The output factor used for monitor unit determination in radiotherapy can be divided into two factors: the head scatter factor and the phantom scatter factor. Theoretical and experimental phantom scatter factors have been compared for different beam qualities between 4 MV and 50 MV and field sizes from 5 cm x 5 cm to 30 cm x 30 cm. The theoretical data were obtained through a convolution method based on Monte Carlo calculated energy spectra and dose kernels. The calculations have been performed both for accelerators with a rather large energy variation within the field and for accelerators with a constant energy distribution in the field. Deviations between theoretical and experimental data were found to be less than 1%.     

The efficacy of psychotherapy as the basis for public policy.

Discusses the tremendous growth that has occurred in the number of mental health providers, the rate of use of mental health services, and public and private reimbursement for mental health care. Governmental policymakers and leading insurance officials continue to seek information regarding the appropriateness and efficacy of specific psychotherapeutic techniques with various types of presenting problems. The efforts during the Carter administration to stimulate additional efficacy research and knowledge synthesis regarding the efficacy of psychotherapy are described. A public policy proposal is forwarded that no form of health intervention—physical or mental—should be supported through 3rd-party reimbursement and publicly supported training programs unless it has been demonstrated to be safe and effective. It is argued that randomized controlled clinical trials should be viewed as the most valid, though not exclusive, source of evidence. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of right and left ventricular volume and ejection fraction using a mathematical cardiac torso phantom

The availability of gated SPECT has increased the interest in the determination of volume and ejection fraction of the left ventricle (LV) for clinical diagnosis. However, the same indices for the right ventricle (RV) have been neglected. The objective of this investigation was to use a mathematical model of the anatomical distribution of activity in gated blood-pool imaging to evaluate the accuracy of two ventricular volume and ejection fraction determination methods. In this investigation, measurements from the RV were emphasized. METHODS: The mathematical cardiac torso phantom, developed to study LV myocardium perfusion, was modified to simulate the radioactivity distribution of a 99mTc-gated blood-pool study. Twenty mathematical cardiac torso phantom models of the normal heart with different LV volumes (122.3 +/- 11.0 ml), RV volumes (174.6 +/- 22.3 ml) and stroke volumes (75.7 +/- 3.3 ml) were randomly generated to simulate variations among patients. An analytical three-dimensional projector with attenuation and system response was used to generate SPECT projection sets, after which noise was added. The projections were simulated for 128 equidistant views in a 360 degrees rotation mode. RESULTS: The radius of rotation was varied between 24 and 28 cm to mimic such variation in patient acquisitions. The 180 degrees and 360 degrees projection sets were reconstructed using the filtered backprojection reconstruction algorithm with Butter-worth filtering. Comparison was made with and without application of the iterative Chang attenuation correction algorithm. Volumes were calculated using a modified threshold and edge detection method (hybrid threshold), as well as a count-based method. A simple background correction procedure was used with both methods. CONCLUSION: Results indicate that cardiac functional parameters can be measured with reasonable accuracy using both methods. However, the count-based method had a larger bias than the hybrid threshold method when RV parameters were determined for 180 degrees reconstruction without attenuation correction. This bias improved after attenuation correction. The count-based method also tended to overestimate the end systolic volume slightly. An improved background correction could possibly alleviate this bias.     

Vocal mechanics as the basis for phonosurgery

OBJECTIVE: A number of modifications in laryngoplastic phonosurgery have recently been proposed. This report is intended to clarify the concept on which the surgery should be based, vocal mechanics, for further rational development of the surgery. STUDY DESIGN: The results of various previous surgeries were compared. In an attempt to elucidate what makes the difference in the results, simulation of voice production was conducted with the use of excised larynges. METHODS: Excised larynges were mounted on a tube so as to be blown from below. Experimental variables in the model included the glottal area initially set, stiffness of the vocal folds, and subglottal pressure. The conditions under which the voice became hoarse were examined. RESULTS: The voice became hoarse under the following major conditions: 1) the initial glottal area exceeded a certain value, 2) stiffness was too high, and 3) the glottis was too tightly closed. Clinical representation for each condition was made, particularly for excessively tight glottal closure such as in spasmodic dysphonia. A new type of surgical treatment for spasmodic dysphonia, lateralization thyroplasty, was briefly reported, which restored the voice to normal without recurrence for 1 year at the time of this writing. CONCLUSIONS: A potential new type of laryngoplastic phonosurgery should be conformed to the mechanics of voice production. In treating dysphonia, it is often necessary to switch from etiologic or radical treatment, if infertile, to symptomatic treatment instead, at the level of mechanics.     

Intercellular interactions as a basis for the expedient behaviour of multicellular systems

Human seminal plasma sperm motility inhibitor (SPMI) proteins which are exclusively secreted from seminal vesicles, inhibit sperm motility. It is secreted as biologically active 52 kDa and a mixture of 71 and 76 kDa precursor forms, which are identical to semenogelin-I and II (Sg-I and Sg-II), respectively. To understand the molecular mechanism underlying the inhibition of sperm motility by SPMI proteins, we expressed human Sg-I and Sg-II genes in insect cells using a baculovirus system. The baculoviruses expressing full-size Sg-I and Sg-II proteins that were N-terminally-tagged with a hexahistidine were selected, and were infected with Sf 21 cells. The Sg-I and Sg-II proteins were purified from infected cells by column chromatography using Ni-NTA resin 48 h after infection. The full-size Sg-I and Sg-II proteins were obtained in soluble forms. However, they tended to aggregate to form a gel, as expected from naturally occurring semenogelin. Both the purified recombinant Sg-I and Sg-II proteins showed strong SPMI activities with a complete inhibition of sperm motility at 60 units/mg, equivalent to the natural proteins. This production system that permits the generation of purified Sg-I and Sg-II proteins, as well as mutant derivatives, will be helpful for further study on male infertility.     

The mechanism of the development of the synapse as the basis for its involution

The electron microscopic investigation of human brain synaptic organization in normal aging and in ischemic heart pathology in different life periods was performed. A significant quantity of desmosome-like and mixed contacts was shown. Their ultrastructural organization was similar to that of developing synapses during prenatal ontogenesis and in newborn rats. The analysis of the experimental results suggests that an appearance of desmosome-like contacts in the human brain results from synapse involution. This is supported by the observation of formation of mixed contacts which may be a transitional stage between symmetrical or asymmetrical specialized synapse and desmosome. Thus, the mechanism of synaptic involution appears to be a mirror reflection of the mechanism of its development.     

Comparison of finite-difference transport and diffusion calculations for photon migration in homogeneous and heterogeneous tissues

We analyse the limits of the diffusion approximation to the time-independent equation of radiative transfer for homogeneous and heterogeneous biological media. Analytical calculations and finite-difference simulations based on diffusion theory are compared with discrete-ordinate, finite-difference transport calculations. The influence of the ratio of absorption and transport scattering coefficient (mu(a)/mu'(s)) on the accuracy of the diffusion approximation are quantified and different definitions for the diffusion coefficient, D, are discussed. We also address effects caused by void-like heterogeneities in which absorption and scattering are very small compared with the surrounding medium. Based on results for simple homogeneous and heterogeneous systems, we analyse diffusion and transport calculation of light propagation in the human brain. For these simulations we convert density maps obtained from magnetic resonance imaging (MRI) to optical-parameter maps (mu(a) and mu'(s)) of the brain. We show that diffusion theory fails to describe accurately light propagation in highly absorbing regions, such as haematoma, and void-like spaces, such as the ventricles and the subarachnoid space.     

The observer-relative velocity field as the basis for effective motion parallax.

Earlier studies of motion parallax found unambiguous relative depth perception when random dot patterns were systematically translated in accordance with either motion of the observer's head or motion of the display scope. The need for such relative motion between an observer and a flow field was examined by placing a flow field in a limited area (window) in a large scope and translating the window relative to the observer. Accuracy in judging surface orientation and quantitative depth estimates were determined by the velocity field relative to the observer and were not measurably affected by whether this field was produced with a stationary or a moving window. Accuracy was consistently higher for smaller ratios of maximum to minimum projected velocities, reaching 100% in one experiment with a 1.12:1 ratio. We conclude that fully effective motion parallax does not require relative motion between the observer's head and the contours of a flow field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)