RESUMEN

Hereditary haemorrhagic telangiectasia (HHT) is a familial, autosomal, dominant, multi-system, vascular, dysplasia. Besides repetitive epistaxis, cutaneous eruptive macules and nodules lead to recurring bleeding and cosmetic problems. We report on a pilot study of four cases of HHT in which cutaneous lesions were treated with a pulsed neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (1,064 nm). Pulsed Nd:YAG laser treatment, without anaesthesia, was performed several times on eruptive angiomas on palmar and facial skin. Lesions on fingers and face mostly showed very good, or even complete, clearing after the first laser treatment. Several macules required multiple treatment; only a few lesions showed no effect. Pulsed Nd:YAG laser therapy (1,064 nm) appears to be an effective and safe treatment option for hereditary haemorrhagic telangiectasia on the skin of face and extremities.

Asunto(s)

Asunto(s)

RESUMEN

Many times when we conduct experiments, we often forget that after the system is perturbed, it usually returns to an equilibrium state, and analysing the manner in which it returns may yield information about the system. In this paper, I illustrate this fact by examining two different biomedical systems.

Asunto(s)

RESUMEN

The Differential Buoyancy method uses Archimedes' principle to non-invasively determine body fat percentage by measuring the subject's weight in breathable high and low densities atmospheres. We currently use both air and helium/oxygen mixtures in our experiments[1]. When the method was tested on rats, an anomaly was observed. As helium/oxygen mixture was admitted to the weighing chamber, while the atmospheric density monotonically decreased, the rat's weight first increased but then after several minutes decreased. Water loss from the rat's body was found to be the main cause of this anomaly. Therefore it was necessary to compensate for this water loss. Consistent with experimental findings the water loss was modeled as a constant rate process, and determined experimentally from weight measurements at the beginning and at the end of the experiment. Making these corrections allowed for accurate predictions of the rat's volume and body fat percentage.

Asunto(s)

RESUMEN

Measurement of body fat percentage is essential for medical care and research. The "gold standard" method for humans is underwater weighing, which is clearly inappropriate for infants, sick people and non-human animals. The corresponding criterion method for animals is comminution of the carcass followed by extraction of the fat with a volatile solvent such as ether. Our goal has been to develop a method for body composition (fat percentage) for use in animals and humans which is non-invasive and minimally intrusive, independent of variation in body conformation and fat distribution, and reasonable in cost. In one variant, our approach to this problem has been to move Archimedes' principle "on to dry land." The subject's volume is determined by measuring the differential buoyancy in comfortably breathable light (low density) and heavy atmospheres. In another, we use "structured light," in which a pattern of illumination is cast on the patient. The image is acquired using a video camera and the geometrical spatial coordinates of a large number of points on the surface of the subject are acquired. This permits the computation of the surface area and volume of the subject; which, combined with the weight, determines the fat percentage.

Asunto(s)

Asunto(s)

RESUMEN

A theoretical approach to modeling Circular Intensity Differential Scattering (CIDS) of native chromatin as multiple scattering of dipoles is discussed without the Born approximation. The model can explain the experimental data in the literature. It is shown that CIDS contains more structural information than does total light scattering and to a good approximation is independent of the length of the scattering molecules. Finally, CIDS in conjunction with traditional light scattering measurements should aid in discriminating between various alternative models of higher order chromatin structure now being proposed. Generalization of this theoretical study to other complex biomolecular structures, is also briefly discussed.

Asunto(s)

RESUMEN

For a better understanding of data provided by DNA alkaline elution technique, a new analytical model has been developed which takes into consideration both the physicochemical properties of in situ DNA strand (length and flexibility/superpacking) and the geometric and hydrodynamic configuration of the elution apparatus (flow and filter conditions). Simulation by this model of experimental data previously obtained before and after carcinogens administration, has shown that for constant flow and filter conditions elution profiles are dependent, not only from DNA molecular weight, but also from a parameter critically related to modifications in chain flexibility/superpacking. This has been confirmed by several independent observations, including the time-dependent changes in non-denaturing lysing solution monitored by hydroxylapatite and alkaline elution techniques.

Asunto(s)

RESUMEN

PHA-stimulated human lymphocytes (normal-resting-proliferating) at 0, 24, 48, 72, and 144 h were studied with Acridine Orange (AO) staining. By viable cell sorting, by subsequent subculturing, and by the use of biochemical, biophysical, and immunological assays, not only have the G0 resting and G1 (cycling) cell cycle phases been objectively characterized, but a separate subpopulation of quiescent cells that are functionally viable and deeply committed to nonproliferation, the Q cells, has been identified. Multiparameter cytofluorimetric analysis, methyl14C-thymidine incorporation, automated image analysis, and mitogen stimulation studies have shown that the "Q" cell, compared to the "G0" resting but easily recruitable cell, exhibits quite lower red and green AO emission, possesses 2c to 4c DNA content (rather than only 2c), has a higher average optical density, and is either nonrecruitable or recruitable-with-difficulty in PHA-stimulated lymphocyte cultures.

Asunto(s)

RESUMEN

Nuclear DNA-space images from Feulgen-stained HeLa cells synchronized at 1, 3, 5, 8, 12, 15, and 18 h following mitosis are digitized and their densitometric-geometric patterns are analyzed by means of a Quantimet 720-D image analyzer on line with a PDP11/40 computer. Frequency distributions of picture point optical densities for the phases and subphases as seen in nuclear images show that DNA packing changes are evident by means of ordinary optical microscopy. Radii of gyration of the images, and optical density profiles and distributions for several squashes of similar cells reveal that in particular instances chromatin DNA is distributed mostly towards the periphery, and usually with high circular isotropy. Cross power spectra of individual scan lines suggest that existence of higher order "quinternary" periodic structure for chromatin that modulates during the cell cycle. Three-dimensional reconstruction 2- micrometer sections of intact, Feulgen-stained mammalian tumor tissue show stainable material only toward the nuclear perimeter and not in the center (compatible with the evidence that initial thymidine incorporation in HeLa cells is generally at the nuclear border). Densitometric properties of reconstructed interphase chromatin-DNA bodies are highly coupled with similar properties of the whole nucleus, showing that a more condensed nucleus is always accompanied by a more condensed interphase chromatin DNA. The effect of micrococcal nuclease digestion on the digitized nuclear images is also presented. All the above data are then discussed in terms of a quinternary chromatin-DNA structure and its modulation during the cell cycle.

Asunto(s)

RESUMEN

A new mathematical method is presented to analyze a time sequence of DNA distributions taken from perturbed cell populations. The method, called FPi analysis, consists of plotting the time variation of the fraction of cells in selected DNA contents 'windows' of the histogram. It is shown that kinetic information about the flow of cells through the cycle after the perturbation can be estimated from the FPi curves. An analysis of the method reveals that the method yields accurate results for the instrumental and cytochemical variations obtainable by present technology. The value of the method lies in the fact that the information needed can be obtained directly from the measured DNA distribution, thus bypassing the problems with other methods which estimate the fraction of cells in a given phase directly from a single histogram.

Asunto(s)

RESUMEN

In a previous report, we described a new method called FPi analysis to analyze time sequences of DNA histograms taken from a perturbed population of cells. In this paper we utilize the method to analyze the in vivo kinetic response of bone marrow and of lung metastases of the B16 tumor to various chemotherapeutic agents. We show that the technique allows useful kinetic data to be obtained with minimal processing of the raw histograms, thus allowing fast analysis of the data. We also show that, in order to monitor the kinetic response of living tissues, it is essential to collect multiparameter distributions; to monitor only the one dimensional fluorescence histogram can give rise to misleading results. Using these multiparameter histograms, we are also able to monitor the growth fraction of the lung metastases during treatment, allowing discrimination between cell synchrony and cell recruitment from the resting compartment.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

We show that by measuring the joint distribution of fluorescent and scattered light in a suspension of lung taken from the C57B1/6J mouse, we are able to discriminate in vivo between the lung metastases of the B16 melanoma and the normal lung tissue. We can in such a way detect metastatic cells in a very early stage of growth and also obtain growth curves for the metastatic population. We analyze the sensitivity of the method of detection and speculate how it might be used in aiding in human diagnosis.

Asunto(s)

RESUMEN

Data presented show that the cell cycle time of the lung metastases from a B16 melanoma tumor growing in the foot pad of C57 BL/6J mice increases as the size of the metastases increases. This increased cell phase durations of the small metastases being closer to those of the primary tumor. The growth fractions of the primary tumor and of the lung metastases of different sizes are analyzed.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)