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At least 1,531 records · Page 85Linked to original sources
PubMed2006

Analysis of shrinkage of different gutta-percha types using optical measurement methods.

The aim of this study was to compare the shrinkage of alpha- and beta-gutta-percha of the Multifill-system with commercial gutta-percha. Ten gutta-percha blocks of each of the three types were used. Speckle pattern shearing interferometry was used to prove that no trapped air and material defects were present in the specimens. The optical triangulation method was applied to assess shrinkage. The three gutta-percha types were examined after heating up to 90 degrees C and cooling down to 35 degrees C. Commercial gutta-percha showed less shrinkage (6.5%) than alpha- (7.2%) and beta-gutta-percha (7.3%; p=0.0051 for both comparisons; Wilcoxon's signed rank test). There was a significant difference between alpha- and beta-gutta-percha (p=0.0093; Wilcoxon's signed rank test). In the range of 45 degrees C to 40 degrees C, alpha- and beta-gutta-percha revealed the highest shrinkage (2.2%/5 degrees C and 2.1%/5 degrees C, respectively). Commercial gutta-percha showed the highest shrinkage (1.1%/5 degrees C) in the range of 55 degrees C to 40 degrees C. Overall, shrinkage of all types of gutta-percha was higher than could be assumed from former studies.

Cold Temperature↗
PubMed1990

[Changes in the erythron during prolonged hemorrhages].

Studies of erythron reaction in prolonged hemorrhages have shown that the index of erythro- and normoblast maturation is reduced in such patients, this evidencing impaired proliferation and differentiation of the erythron system cells. Red cells distribution in the peripheral blood during interferometry has demonstrated that the level of solid matter in patients' red cells is essentially reduced and correlates with the severity of anemia. These data may be valuable when assessing the severity of the erythron system impairment and its recovery due to therapy.

Adult↗
PubMed1991

From radio-astronomy to medical imaging.

A common thread in much of the medical imaging that has developed over the past 20 years has been the Fourier transform. It was Richard Bates' interest in radio-interferometry, as well as his fascination with problems of medical imaging that prompted an initial interest in applying Fourier techniques to medical imaging in general and to Computed Tomography in particular. This resulted 20 years ago in one of the earliest technical papers advocating Fourier techniques for reconstructing cross-sections from radiographic projections (Bates and Peters, NZ J Science 14:883-896, 1971). Since those early days, medical imaging has explored into a multi-billion dollar industry. The CT scanner has become the workhorse imaging modality in the radiology department, while its more recent relative, the MR scanner, is rapidly gaining ground as a technique of even greater importance. Richard Bates, with his team of "Medical Imagers" was a very significant force in the development of the field of Medical Imaging as we know it today. This paper attempts to chronicle the genesis of this process from the personal perspective of the author.

Diagnostic Imaging↗
PubMedDate not supplied

Wear measurements in clinical studies of composite resin restorations in the posterior region: a review.

During the last twenty years, wear-evaluation methods have changed, with newer techniques developed to determine the extent of loss of material in posterior composite resin restorations functioning in the mouth. These included: direct clinical evaluation; marginal evaluation on models; heights of exposed cavity walls; volumetric assessment of impressions; profilometry and artificial or natural references; section measurements; coordinate measuring device, contact and noncontact scanning; measuring microscope; photogrammetry; moiré topography; laser interferometry; scanning electron microscopy; and optical scanning. A laser scanning technique appears to hold great potential in clinical research.

Bicuspid↗
PubMed1990

[A comparative analysis of the morphochemical changes in the neurons of the visual and sensorimotor cortices and the nucleus accumbens of rats administered tuftsin].

White rats were treated with a single administration of tetrapeptide tuftsin (Thr-Lys-Pro-Arg) in the dose 300 mcg/kg (b.w). Using interferometry, the protein content and concentration were assessed 15, 30 and 60 minutes after injection. The area of the neuron cytoplasm and nucleus were measured too. The nucleoplasmic balance and dispersion were calculated. Significant alterations in the protein contents and cellular area, nucleoplasmic balance and dispersion were detected in neurons of visual, sensomotor cortex and of n. accumbens. A possible interrelation is discussed between tuftsin action and the functional activity of neurons, between the level of their protein metabolism and establishment of emotional and motor response.

Animals↗
PubMed1988

Presurgical prediction of postsurgical visual acuity in patients with media opacities.

Of the estimated 1 million patients each year in the United States who undergo surgery for media opacities, perhaps 5-10% fail to improve because of pre-existing, undiagnosed retinal and/or optic nerve disease. In this paper, the standard presurgical evaluation (case history, visual acuity, refraction, pupillary response testing, biomicroscopy, ophthalmoscopy, tonometry, visual fields and color vision) and the supplementary presurgical evaluation (entoptic phenomena appreciation, ophthalmic ultrasonography, fluorescein angiography, laser interferometry, potential acuity meter, visual evoked potential, electroretinography, contrast sensitivity and hyperacuity measurements) are reviewed.

Cataract↗
PubMed1979

[Rhythm of protein concentration and incorporation of 3H-lysine into hepatocytes in vitro].

"In vitro" incubated slices of the rat liver, by the method of interferometry combined with radioautography, have demonstrated hour's rhythmic fluctuations in protein concentration and 3H-lysine incorporation into proteins. The biochemical method has demonstrated fluctuations in protein synthesis rate in the same cells with an average period of about one hour. The possibility to apply the interferometric method in combination with radioautography for revealing quantitative changes of protein in slices of organic cultures is demonstrated.

Animals↗
PubMed1984

[Artificial synovial fluid for the intra-articular treatment of rheumatoid arthritis and osteoarthritis (chemical synthesis and clinico-experimental and biomechanical data)].

Based on the clinical, experimental and biomechanical studies the authors suggest intraarticular treatment of rheumatoid arthritis (RA) and deforming osteoarthrosis (DOA) by means of artificial synovial fluid (ASF) developed with the use of polymers and biopolymers. Rheological studies performed with the use of a Rheotest-2 apparatus and ultrasonic interferometry of the samples of normal, RA, DOA synovial fluid and ASF demonstrated that medium-molecular-weight polyvinylpyrrolidone (PVP) and PVP hyaluronate appeared the most similar to natural synovial fluid, PVP-hyaluronate, PVP and its complexes with other drugs (cyclophosphamide, hydrocortisone, arteparone) were applied intraarticularly to the treatment of 520 patients with RA and DOA. The group of patients who received kenalog or placebo intraarticularly served as control. Over 3000 intraarticular administrations of ASF and its complexes were made altogether. No side effects were observed. In the articular medium, PVP displayed lubrication, anti-inflammatory, prolonging, anticommissural and other effects. Attention is drawn to the immunoregulatory action of PVP. The treatment with artificial articular lubricants promoted the improvement of the function of the joints and positive time-course of some clinical, laboratory, biochemical and immunological characteristics.

Aged↗
PubMed1995

[Prediction of postoperative visual acuity in retinal detachment with macular involvement].

We used laser interferometry (LI) and a potential acuity meter (PAM) to predict visual acuity after surgery for patients with rhegmatogenous retinal detachment with macular involvement. Thirty one eyes of 31 patients with retinal detachment were treated with scleral buckling procedures. Postoperative visual acuity was correlated with preoperative measurements of the LI and PAM, preoperative visual acuity by Landort's ring, and the estimated duration of macular detachment. The correlation between the duration of macular detachment and the postoperative visual acuity was not good (r = 0.55, p < 0.01). Although the preoperative visual acuity showed a relatively good correlation with postoperative visual acuity (r = 0.62, p < 0.01), the results of the LI and PAM provided a better correlation (LI; r = 0.73, PAM; r = 0.71). Our results suggest that the LI and PAM are useful to predict the visual acuity after retinal reattachment in patients with preoperative macular detachment.

Humans↗
PubMed1994

[Functional capacity of fibrinogen and erythrocyte aggregation in the diabetic].

The aim of this work is to study the possible influence of a qualitative modification of fibrinogen on its capacity of erythrocyte aggregation. Fibrinogens were isolated and then purified from blood sample of 15 insulin-dependent diabetics and of 7 healthy subjects. The erythrocyte aggregative effect of the purified fibrinogens was measured for various concentrations (0 g/1-5 g/l). The erythrocyte aggregation was determined by the ECHO CELL whose functioning principle is based upon ultrasonic interferometry. Results allow one to distinguish three kinds of fibrinogen: the first kind inducing a similar erythrocyte aggregation as that obtained by the fibrinogens from healthy subjects, the second kind inducing an erythrocyte hyperaggregation, the third kind inducing an erythrocyte hypoaggregation. Thus the possibility of a qualitative abnormality of fibrinogen, affecting its erythrocyte aggregative capacity in diabetic patients, could be suggested. This qualitative abnormality of fibrinogen might be due to a modification of its molecular structure because of an abnormal elevated glycation during diabetes.

Adult↗
PubMed1994

Clinical hemolysis with the St. Jude heart valve without paravalvular leak.

In 1990 and 1991 we operated on 2 patients with persistent clinical hemolysis, in the absence of perivalvular leaks, who had had their mitral valves replaced with St. Jude Medical valve (SJMV) prostheses. The valves had been implanted 14 months and 3 months before, respectively. There were no other discernible causes for the hemolysis and when each SJMV was replaced the hemolysis disappeared in that patient. The first valve was not tested in the laboratory owing to its loss, but it looked normal. The second valve was tested and found to have regurgitation well within the usual limits for this valve. Fringe pattern interferometry indicated that the leading edge of each leaflet was flatter and less smooth than that of another SJMV. Reviewing the literature we find that idiopathic, persistent clinical hemolysis in recipients of St. Jude mechanical heart valves is a rare phenomenon, which has appeared in 4 reports totaling 9 cases. We discuss the suggested mechanisms involved, and add the possibility of leading leaflet edge characteristics.

Aged↗
PubMed1994

[Hemi-alloarthroplasty with intermediary hip joint endoprosthesis].

Intermediary (bipolar) endoprostheses have been used for the treatment of hip fractures in the past 30 years. Our cinematographic X-ray examinations have confirmed the function of the intra-prosthetic joint in vivo. Physiological load distribution in the acetabulum of "hard-top" cups was demonstrated in an experimental model by holographic interferometry. Our follow-up of 634 intermediary endoprostheses which had been implanted in a 15-years period demonstrated good clinical results. But it confirmed that "soft-top" cups should no longer be used because of the problems of polyethylene wear debris from the cup surfaces. Scintigraphic examinations in 123 cases showed the advantage of the test over X-ray examinations in early recognition of acetabular protrusion.

Aged↗
PubMed1993

Phase-shifting interference microscopy applied to the analysis of cell behaviour.

The theory of phase-shifting interferometry is not new but it is only recently, with the advent of solid-state detector arrays and fast image processors, that it has become a practical imaging technique. In conjunction with transmission interference microscopy, phase-shifting presents a new way of introducing contrast into the images of transparent microscopic objects such as cultured cells. An earlier paper from our laboratory has emphasised the advantages of transmission interference microscopy over phase contrast or differential interference contrast microscopy for the computerised analysis of cell behaviour. Phase-shifting greatly improves the accuracy, long-term stability and range of application of this technique but it has not previously, to our knowledge, been combined with transmission interference microscopy for the study of cultured cells. The resulting image is especially well suited to quantitative analysis by computer since it is a direct representation of the distribution of non-aqueous cellular material in the specimen. The image is not degraded by uneven illumination; by heterogeneous sensitivity of the detector array; or by differential absorption of light in the optics or specimen. Our main purpose in developing the method is to obtain sequences of images of the motile behaviour of cells in culture for analysis by computer. This type of analysis is potentially a powerful tool for studying the motile responses of cells and the operation and control of their locomotory machinery. Not only can the method be used for studying cell translocation and the dynamics of intracellular movement of non-aqueous material, but it is now possible to study in detail the time course of growth in individual cultured cells.

Animals↗
PubMedDate not supplied

[Visualization of the effects of millimeter radiation on blood plasma].

Experiments on millimeter wave radiation (range 37.5-78.5 Ghz incident radiation power density 1-10 mVt/cm2) upon index refraction of 2-10% water solution of human blood plasma are presented. Investigations were carried out by holographic interferometry with sufficient sensitivity for estimating the index refraction -10(-6). Index refraction variations in 2% water solution of human blood plasma are detected to be equal to 10(-4). Such index refraction variations upon millimeter wave is one order greater than that of the temperature effect and two order greater than the sensitivity of settlement. The mechanism of these phenomena is discussed.

Blood↗
PubMed1995

The Visible Human data set: an image resource for anatomical visualization.

The National Library of Medicine (NLM) has long been a world leader in the archiving and distribution of the print-based images of biology and medicine. NLM has also been a pioneer in the use of computer systems to encode and distribute textual knowledge of the life sciences. NLM's Long Range Planning effort of 1985-86 foresaw a coming era where NLM's bibliographic and factual database services would be complemented by libraries of digital images, distributed over high speed computer networks and by high capacity physical media. The NLM Planning Panel on Electronic Imaging recommended that NLM should undertake the building of a digital image library consisting of computer-assisted tomography (CAT), magnetic resonance interferometry (MRI), and cryosection images of a representative, carefully selected and prepared male and female cadaver--the "Visible Human Project." The male Visible Human data set is now being made available through a license agreement with the NLM. A wide range of educational, diagnostic, treatment planning, and commercial uses is predicted. The Visible Human data set and its associated identification maps will serve as a "Boston Teapot" for medical imaging, a common public domain data set against which all medical imaging algorithms can be tested, and a cornerstone for future sets of related image libraries.

Adult↗
PubMed1996

Fine grain of the neural representation of human spatial vision.

It is widely held that in human spatial vision the visual scene is initially processed through visual filters, each of which is responsive to narrow ranges of image spatial frequencies. The physiological basis of these filters are thought to be cortical neurons with receptive fields of different sizes. The grain of the neural representation of spatial vision is much finer than had been supposed. Using laser interferometry, which effectively bypasses the demodulation of the optics of the eye, we measured discrimination of, and adaptation to, high spatial frequency laser interference fringe patterns. Spatial frequency discrimination was good right up to the visual resolution limit (average Weber fractions of 0.13 at 50 c/deg). Both contrast and spatial frequency matches made after adapting to extremely fine interference fringes strongly suggested that there existed even finer, relatively unadapted, filters (mechanisms with small receptive fields). The smallest cortical receptive fields processing spatial information in human vision are so small that they can possess receptive field centers hardly wider than single cone photoreceptors.

Adaptation, Physiological↗
PubMed1977

[Comparative assessment of quantitative methods of determining proteins in nerve tissue structures].

The determination of the amount and concentration of protein substances in structures of neuron tissue by two most popular methods of quantitative histochemistry (cytophotometry and interferometry) revealed a significant comparability of the data provided by the two methods. These methods were compared using the pattern of early vision deprivation, taking layer V neurons of the rabbit brain visual cortex as example. In addition to merits and demerits of these methods, their interchangeability was determined. A merit of cytophotometry is that it allows to evaluate more in detail the condition of neuron morphochemical differentiation both in normal state and under changes in functional state of neuron system.

Animals↗
PubMedDate not supplied

Evaluation of Aegys Mi 600 Fourier transform infrared milk analyzer for analysis of fat, protein, lactose, and solids nonfat: a compilation of eight independent studies.

The Aegys Mi 600 Fourier transform-infrared milk analyzer was evaluated for performance in 8 independent laboratories in Europe, the United States, and Australia. This instrument, equipped with a mid-infrared source, a temperature-controlled transmission flow cell or cuvette, and detection device, uses interferometry for wavelength generation; multilinear regression was used to create calibration equations for measurement of fat, protein, lactose, and solids nonfat. Each instrument was tested independently for various performance criteria including but not limited to accuracy in calibration and validation, repeatability, and purge efficiency. Mean difference for accuracy and standard deviation of differences for accuracy observed in each laboratory were well within AOAC requirements (< 0.05 and < 0.06%, respectively) as were the mean of differences for repeatability and the standard deviation of differences for repeatability (< 0.02 and < 0.02%, respectively). Observed purge efficiency was better than 99.0%. In addition, zero stability, instrument reproducibility over 5 days without recalibration, and homogenization efficiency were successfully tested. On the basis of the results, each instrument tested was approved for use for milk payment and/or dairy herd improvement in the country in which it was tested. The results demonstrate that the Aegys Mi 600 meets the requirements of the AOAC Official Method 972.16. The mid-infrared spectroscopic method for determination of fat, lactose, protein, and solids in milk has been modified and adopted revised first action by AOAC INTERNATIONAL.

Absorption↗