Measuring cellular structure at submicrometer scale with lightscattering spectroscopy

We present a novel instrument for imaging the angular distributions of light backscattered by biological cells and tissues. The intensities in different regions of the image are due to scatterers of different sizes. We exploit this to study scattering from particles smaller than the wavelength of light used, even when they are mixed with larger particles. We show that the scattering from subcellular structure in both normal and cancerous human cells is best fitted to inverse power-law distributions for the sizes of the scattering objects, and propose that the distribution of scattering objects may be different in normal versus cancerous cells     

Tuberculosis after intestinal bypass operations

Two cases of tuberculous infections occurred after intestinal shunt operations for obesity among 161 patients observed for more than one year. One died of generalized tuberculosis. Another 2 patients, who before the operation had had tuberculosis, managed well without signs of postoperative activation of the tuberculous infection seems to be unpredictable.     

Equiphase-sphere approximation for analysis of light scattering by arbitrarily shaped nonspherical particles

We extend the previously proposed concept of equiphase sphere (EPS) to analyze light-scattering properties of arbitrarily shaped particles. Our analyses based on the Wentzel-Kramers-Brillouin technique and numerical studies based on the finite-difference time-domain method demonstrate that a wide range of irregularly shaped particles can be approximated as their equivalent equiphase ellipsoids to determine their total scattering cross-section (TSCS) spectra. As a result, a simple expression given by the EPS approximation can be used to calculate the TSCS spectra of these particles. We find that the accuracy of the EPS approximation is influenced by both the magnitude and the geometric scale of the surface perturbation of the particle, and we derive validity conditions of the EPS approximation to guide the practical application of this method.     

Effects of age and GDNF on noradrenergic innervation of the hippocampal formation: studies from intraocular grafts

Recent studies have suggested that factors in the target tissue influence the degree of plasticity and regeneration following aging and/or specific insults. We have investigated whether young or aged targets differ in their noradrenergic innervation from fetal locus coeruleus (LC) neurons, and also if a specific growth factor, glial cell line-derived neurotrophic factor (GDNF) can affect this innervation pattern. Tissue pieces of fetal brainstem and young (3 months) or old (18 months) iris tissue were transplanted simultaneously into the anterior chamber of the eye of adult hosts. We found that aged iris transplants became innervated to a significantly lesser degree by the cografted LC neurons than young iris transplants. Fetal hippocampal tissue was then grafted to adult hosts, and a fetal brainstem graft containing LC neurons was placed adjacent to the first graft, either at 3 or 21 months post-grafting. Thus, old/young chimeras of the noradrenergic coeruleo-hippocampal pathway were created. Aged hippocampal grafts received a much less dense innervation from co-grafted LC neurons than young hippocampal grafts. Tyrosine hydroxylase-positive-immunoreactive innervation was only found in the outskirts of aged grafts, while the young hippocampal grafts contained an even innervation pattern. The innervation density of hippocampal grafts was significantly enhanced by GDNF treatment. These findings demonstrate that target-derived factors may regulate neuronal plasticity, and that the age of the target is more important for innervation properties than the age of the neuron innervating a particular target.     

Validating the Marschak Interaction Method Rating System with adolescent mother-child dyads.

The authors investigated the reliability and construct validity of the Marschak Interaction Method Rating System (MIMRS), a new observational scoring system for the play-based Marschak Interaction Method (MIM), particularly its ability to capture high-risk parenting in adolescent mother-child dyads. The MIMRS demonstrated high interrater reliability and high internal consistency. Convergent validity was supported by moderately negative correlations between the MIMRS and the Parenting Stress Index/Short Form. The MIMRS demonstrated good contrasted groups validity, differentiating between 15 adolescent-child dyads and 16 adult- child comparison dyads, even after adjustment for differences in children's age. These results suggest that the MIMRS has the potential be a valuable rating system for research and practice with the MIM, as well as understanding and assessing parent-child relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interaction between wood and polyurethane‐alkyd lacquer resulting in a decrease in the glass transition temperature

The long‐term properties of paint and glue are of great interest to both manufacturers and users of these materials. If a good bond is achieved, the surface between the wood and the paint or glue will be less susceptible to degradation. Thus, the wood and polymer must be compatible and develop some kind of bonding force between them. A high degree of interaction between wood and commercial polyurethane‐alkyd lacquer was shown as a decrease by 10°C of the glass transition temperature (T_g) for the lacquer on wood compared to the pure lacquer. The lacquer also demonstrated good adhesion to wood at a microscale. The interaction was investigated with dynamic mechanical thermal analysis and scanning electron microscopy fractography. The reason for the decrease in Tg is probably because of the lacquer having a higher free volume when applied to the wood, most likely due to it being subjected to tensile forces developed during the drying of the lacquer. Results from investigations of wood impregnated with two different acrylates, a polymethylmethacrylate and a more hydrophilic acrylate, support the suggestion that a decrease in T_g will occur if the polymer adheres to wood, but that poor interaction with little or no adhesion will result in no decrease in T_g. This article also presents results of the dynamic mechanical behavior of Scots Pine in the tangential direction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 595–605, 2002     

Degeneration at the insertion weakens the tensile strength of the supraspinatus tendon: a comparative mechanical and histologic study of the bone-tendon complex

The purpose of this investigation was to determine the relationship between the degree of degeneration at the supraspinatus insertion, the tensile strength, and the site of failure of this tendon. Thirty-three fresh cadaveric shoulders (average age: 62 years; range: 39-83 years) were examined. A tensile load to failure was applied at a constant crosshead speed of 25.4 mm/min to a 10 mm wide strip of the supraspinatus tendon that remained attached to the bone. Preexisting degenerative changes at the insertion were assessed and scored histologically and compared with the ultimate tensile stress. Twenty tendons failed at the insertion (the insertion group), and 11 failed in the midsubstance (the midsubstance group). The histologic score of degeneration for the insertion group was significantly higher than that for the midsubstance group (p = 0.0026). There was a negative correlation between the ultimate tensile stress at the insertion and the degeneration score for the insertion group (r = -0.60; p = 0.013). Histologic observations revealed that disruptions of tendon fibers were located mostly in the articular half of the tendon and that they enlarged during mechanical testing in 90% of the specimens of the insertion group. It seems that degenerative changes at the supraspinatus insertion reduce the tensile strength of the tendon and constitute a primary pathogenetic factor of rotator cuff tear.     

Recent progress in exact and reduced-order modeling of light-scattering properties of complex structures

An emerging research area in biophotonics with potentially near-term clinical applications in early stage cancer detection involves the investigation of possible correlations of the elastic light scattering properties of tissues with alterations in their cellular composition and nanostructure. Until recently, exploring these correlations has been impeded by a lack of robust and accurate mathematical models of the light scattering properties of complex structures. In this paper, we review recent progress in this area. Topics include: 1) development of accurate reduced-order expressions for the total scattering cross section spectra of a wide range of nonspherical and inhomogeneous particles; 2) rigorous finite-difference time-domain modeling results showing how the backscattering of light can be sensitive to nanometer scale features embedded within micrometer-scale particles; and 3) development of accurate reduced-order expressions for the backscattering depolarization properties of a wide range of inhomogeneous particles. These advances provide an improved science base for cellular level biophotonics, and have promise to accelerate the development of novel corresponding clinical technologies.     

Biliary reflux can be a contributory cause of esophagitis

In recent years duodenogastric reflux has been recognised as a possible cause of oesophagitis. Alone or in combination, bile salts, trypsin, pepsin, and hydrochloric acid have all been shown to cause oesophagitis. Duodenal content in the oesophagus can be measured by means of a new fibre-optic sensor, Bilitech 2000, a device measuring the occurrence of bilirubin and yielding 24-hour readings from the distal oesophagus. Studies in which the device has been used have shown oesophageal bilirubin to be increased in patients with oesophagitis, especially in the subgroup with such complications as oesophageal stricture or ulceration, or Barrett's oesophagus. The evidence suggests that unsatisfactory response to proton pump inhibitors in reflux patients might be due to an increase in duodenal reflux, and should be treated surgically with fundoplication or biliary diversion. This may also be true of oesophagitis patients with complications, though this remains to be shown in clinical studies.