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Biomedical subjects

R Lyon

Publications and source records attributed to R Lyon.

32 records · Page 2Linked to original sources
PubMed1985

Ultrastructure and energy-dispersive x-ray microanalysis of cartilage after rapid freezing, low temperature freeze drying, and embedding in Spurr's resin.

In order to undertake meaningful high-resolution x-ray microanalysis of tissues, methods should be used that minimize the introduction of artefacts produced by loss or translocation of ions. The most ideal method is rapid freezing but the subsequent sectioning of frozen tissues is technically difficult. An alternative method is to freeze dry the tissues at a low temperature, and then embed them in resin. This facilitates the rapid production of reproducible thin sections. With freeze-dried, embedded hypertrophic cartilage, the morphology was similar to that seen using aqueous fixatives even when no additional electron density is introduced by the use of osmium vapor. Energy-dispersive analysis of specific areas show that little or no loss or migration of ions occurs from structures such as mitochondria. Mitochondrial granules consisting of calcium and phosphorus precipitates were not observed except where the cells were damaged as a result of the freezing process. This may suggest that these granules only appear when tissue is damaged because of inadequate preservation.

Animals↗
PubMed1984

The ultrastructure and metal-containing inclusions of mature cell types in the hepatopancreas of a crayfish.

The ultrastructure of the hepatopancreas of the crayfish Austropotamobius pallipes (Lereboullet) is described in relation to its function in digestion. X-ray microprobe analyses of the cells of this tissue have been obtained after using a variety of fixatives and plasma oxygen etching. The distribution of metals in the digestive cells is considered in relation to the polarization of the cells and their ability to absorb materials across the apical and basal cell membranes.

Astacoidea↗
PubMed1984

Metal-protein binding patterns in the hepatopancreas of the crayfish (Austropotamobius pallipes) during short term cadmium stress.

Cd-binding patterns in the hepatopancreas of the crayfish (Austropotamobius pallipes) have been analysed in response to the administration of a single dose of Cd ions. Four main components, with apparent molecular weights of 3-4, 12, 20 and greater than 70 K daltons, have been isolated from soluble cell fractions. The variation in molar metal/protein ratios of these components is discussed in terms of the uptake, transfer and detoxification of Cd in the hepatopancreas. A model is proposed which describes Cd flux at the subcellular level and indicates that metallothionein-like proteins may mediate in this process.

Animals↗
PubMed1983

Effects of a combination of common snack foods on some risk factors in heart disease and diabetes in rats.

Rats were fed ad libitum diets containing a combination of commonly consumed highly palatable snack foods, a commercial stock diet, or had access to both diets for 10-11 weeks. Rats fed snack foods only had elevations in risk factors associated with heart disease and/or diabetes including serum cholesterol, insulin response to glucose, and serum glucose. Triglyceride levels were not affected by diet. Removable fat pad weights (perirenal and epididymal) were greater in rats fed snack foods than in rats fed only stock diet, even though total body weights were less. Liver glucose 6-phosphate dehydrogenase activity was not affected by diet, but malic enzyme activity was greater in rats fed snack foods only than in the other two groups. These results indicate that some risk factors associated with heart disease and/or diabetes can be elevated by feeding a diet containing commonly consumed snack foods.

Adipose Tissue↗
PubMed1983

Effect of chronic hyperinsulinism on metabolic parameters and histopathology in rats fed sucrose or starch.

The purpose of this study was to determine the effects of chronic hyperinsulinism on metabolic risk factors and on the histopathologic changes in the heart and aorta of rats fed sucrose or starch diets for 8 months. Hyperinsulinism was attained by the subcutaneous implantation of osmotically driven minipumps partially coated with paraffin so as to deliver 3 units/day of porcine insulin for up to 4 weeks. Control rats were implanted with pumps containing 1.6% glycerol. There were initially 12 rats each in four groups of rats; sucrose-insulin, sucrose-control, starch-insulin, starch-control. Nonfasted blood insulin levels obtained every 3 weeks from the tail vein averaged 553, 156, 426, and 107 microU/ml in sucrose-insulin, sucrose-control, starch-insulin, and starch-control rats, respectively. Sucrose-fed rats had greater body weight, deposited more body fat, and had higher levels of nonfasting insulin and glucose and 6-hour fasted triglyceride than did starch-fed rats. Rats receiving insulin had greater body weight and removable fat weight, higher levels of nonfasting and fasting insulin and lower level of nonfasting glucose than did rats not receiving insulin. Neither hyperinsulinism nor the type of dietary carbohydrate significantly affected the amount of blood cholesterol. Histopathology of the heart and aorta revealed no unique changes above those commonly observed in laboratory rats as a function of age.

Animals↗
PubMed1982

Addition of sodium metabisulphite to left atrial catheter infusates as a means of preventing bacterial colonisation of the catheter tip.

Sodium metabisulphite (SMBS) was added at a concentration of 0.05% to the dextrose-heparin solution used to flush left atrial catheters in one group of open-heart surgery patients. Two other groups of patients had left atrial catheters flushed with dextrose-heparin alone. Comparison of the isolation rate of organisms from the tips of the catheters in the three groups showed that the addition of SMBS significantly reduced bacterial contamination in the lines (two isolations from 36 catheters with SMBS added, compared with 13 from 56 and 15 from 65 in the other groups--that is, 5.55% compared with 23.2% and 23.1%). The protective effect of the SMBS was particularly evident in the first 48 hours after catheter insertion. No haematological or biochemical insult was found.

Adult↗
PubMedDate not supplied

A safety net to prevent embolization during interventional procedures: work in progress.

PURPOSE: In vitro evaluation of three prototype devices designed to trap emboli that are generated by intravascular procedures. MATERIALS AND METHODS: Three prototypes of the safety net were tested in a water flow model. Angioplasty of human endarterectomy specimens was performed upstream of the device (n = 8). In other tests, polyvinyl alcohol particles were injected into the water flow model upstream of the device (n = 15). The safety nets and the effluent that passed through them were examined for embolic particles. A third prototype was tested (n = 5) to evaluate whether the device could be deployed and retrieved as designed. RESULTS: The safety net was able to trap debris released by angioplasty of endarterectomy specimens in every case. Most, but not all, polyvinyl alcohol particles were trapped by the safety net. Four of five devices tested were deployed and retrieved as designed. One became caught in the introducing valve, which prevented deployment. CONCLUSION: The vascular safety net is effective in trapping small volumes of emboli. It can be deployed and retrieved as designed.

Angioplasty↗
PubMedDate not supplied

Effects of ethanol on reproduction and arterial hypertension in spontaneously hypertensive and normotensive rats: a preliminary communication.

Ethanol consumption and spontaneous (essential) hypertension are important fetal and maternal risk factors. Alone, they contribute to embryopathy (fetal alcohol syndrome) or maternal organ pathology and fetal loss in hypertensive pregnancies. Combined, the effects of ethanol consumption on the progress of a hypertensive pregnancy have not been adequately investigated. In the present study, groups of O-A strain genetic hypertensive (SHR: groups 1 and 2) and Wistar-Kyoto normotensive (WKY: groups 3 and 4) pregnant rats were given 20 ml/kg of distilled water by gavage to serve as controls [groups 1 (SHR) and 3 (WKY)] or 3.2 g/kg of ethanol [groups 2 (SHR) and 4 (WKY)] from days 6 to 15 of gestation. During acclimation, hypertension developed in SHR rats (WKY pressures were 105 to 114 mm Hg; SHR pressures were 137 to 148 mm Hg). From day 6 to 15 of gestation, ethanol-consuming rats (groups 2 and 4) had higher arterial pressures than controls (groups 1 and 3). Pregnant SHR rats given ethanol did not experience a prebirthing hypotension. On gestation day 20, most offspring (84%, group 2; 86%, group 4) of alcoholic dams were dead or malformed. Intrauterine growth retardation occurred in group 4. Hydrocephalus, microphthalmia, and mild hydronephrosis and hydroureter were common in live offspring of group 2 dams. Hydronephrosis and hydroureter were increased in group 4 pups. Variant cranial ossification was noted in group 2 and 4 pups. These preliminary data suggest an altered hypertensive response during pregnancy in alcohol-consuming rats and confirm the embryopathic effects of relatively high levels of ethanol consumed during the critical period of organogenesis in two additional strains of rats.

Alcoholism↗
PubMedDate not supplied

Variability in three-dimensional measurements of back contour with raster stereography in normal subjects.

Forty normal children with a mean age of 9.1 years were investigated by using a Quantec Spinal Image System (QSIS). The QSIS uses computerized raster stereography technology to acquire three-dimensional measurements of back contour. Within a 95-percentile confidence interval (a) coronal-plane QSIS angles ranged from 0.05 to 2.36 degrees; (b) transverse-plane QSIS angles ranged from 0.03 to 1.96 degrees; and (c) sagittal-plane QSIS angles ranged from 36.8 to 44.8 degrees. Trunk-alignment deviation ranged from 3.51 to 7.45 mm within a 95-percentile confidence interval. An intraobserver standard deviation of +/-4.2 degrees was noted across all angular metrics. Normal ranges of QSIS-determined values for a population of 40 children without clinical evidence of pathology are reported.

Back↗
PubMedDate not supplied

Relationship between Quantec measurement and Cobb angle in patients with idiopathic scoliosis.

The Quantec Spinal Imaging System (QSIS) is a raster stereography used to measure three-dimensional trunk images. The Q angle, a coronal plane measurement generated by the Quantec Spinal Imaging System (QSIS), was compared with the Cobb angle in assessment of scoliosis curve magnitude. One hundred forty-nine patients with idiopathic scoliosis were evaluated using both the Quantec system and plane radiographs. The Cobb and Q angles demonstrated significant correlation in the thoracic region (r = 0.65, p < 0.05), lumbar region (r = 0.63, p < 0.05), and in the thoracolumbar region (r = 0.70, p < 0.05). The difference between the Q and Cobb angles was small when the Cobb angle was <21 degrees with less than 6 degrees of axial surface rotation, as measured by the QSIS method. For smaller curves with minimal rotation, there is close correlation between the Cobb angle and the Quantec angle.

Adolescent↗