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Biomedical subjects

S Kelly

Publications and source records attributed to S Kelly.

At least 181 records · Page 10Linked to original sources
PubMed1990

Catheter-based intravascular ultrasound discriminates bicuspid from tricuspid valves in adults with calcific aortic stenosis.

A catheter-based intravascular ultrasound transducer was used to study aortic valve morphology in adults with calcific aortic stenosis. Examination of 14 postmortem specimens disclosed that intravascular ultrasound consistently identified the number of cusps or the presence of a calcified median raphe in the conjoined cusp, or both, and thereby distinguished a calcified bicuspid from a calcified tricuspid aortic valve. These postmortem findings were then employed to identify valvular morphology in 15 patients undergoing diagnostic cardiac catheterization or balloon aortic valvuloplasty, or both. Reproduction of criteria established in vitro allowed discrimination of congenital valvular morphology in all 15 patients, including 7 in whom assessment by intravascular ultrasound was confirmed by subsequent pathologic examination. Identification of aortic valvular morphology by intravascular ultrasound has potential therapeutic implications for patients considered to be candidates for operative or nonoperative aortic valvuloplasty.

Adult↗
PubMed1990

Percutaneous intravascular US as adjunct to catheter-based interventions: preliminary experience in patients with peripheral vascular disease.

Catheter-based ultrasound (US) transducers may be introduced into the vascular system to record high-resolution images of the vessel wall and lumen. The potential advantages and existing liabilities of percutaneous intravascular US as an adjunct to transluminal vascular recanalization were investigated. A 6.6-F braided, polyethylene catheter enclosing a rotary drive shaft with a single-element, 20-MHz transducer at the distal tip was used in 17 patients undergoing percutaneous transluminal (balloon) angioplasty (PTA) alone (10 patients), PTA with implantation of an endovascular stent (two patients), atherectomy alone (two patients), or laser angioplasty with PTA and/or atherectomy (three patients). The arteries treated and examined included the common iliac in five patients, the external iliac in two, the superficial femoral in nine, and a vein graft-arterial anastomosis in one. In 14 cases PTA was employed as sole or adjunctive therapy; plaque cracks were clearly delineated with intravascular US in all 14 (100%) and dissections were observed in 11 (78%). Plaque-arterial wall disruption was less prominent in the arteries treated with mechanical atherectomy. The results of laser angioplasty reflected the adjunctive modality employed. After stent implantation, serial intravascular US documented effacement of PTA-induced plaque cracks and/or dissections. Intravascular US also aided in the quantitative assessment of luminal cross-sectional areas after the procedures (19.0-51.8 mm2). The observations recorded in this preliminary group of 17 patients illustrate the potential utility of intravascular US as an adjunct to conventional angiography in patients undergoing percutaneous revascularization.

Aged↗
PubMed1990

DNA flow cytometry of myocardial cell nuclei in paraffin-embedded, human autopsy, cardiac tissue.

Changes in nuclear DNA occur in myocytes as they grow and hypertrophy. We used DNA flow cytometry to study myocardial nuclei from paraffin-embedded human autopsy tissue. Forty hearts ranging from 310-1040 g were studied. Histograms generated for each heart showed peaks at the 2N and 4N positions. Two of 9 hearts weighing 310-430 g had 8N peaks as well. Fourteen of 17 hearts weighing 450-690 g also had 8N peaks but no 16N peaks. Twelve of 14 hearts weighing 710 to 1040 g had 8N peaks and 4 had 16N peaks as well. Contingency analysis showed statistically significant differences in the ploidy of nuclei from the three different groups of hearts. This study corroborates previous work indicating that DNA ploidy in myocardium increases with hypertrophy. Thus, flow cytometry of paraffin-embedded myocardium should be a useful technique to study DNA from archival material, obviating the need for fresh or frozen tissue.

Cardiomegaly↗
PubMed1989

The child with chronic or debilitating illness.

Children with chronic diseases face particular problems at school. Early recognition of these difficulties and appropriate management should enable most of these children to participate fully in school life.

Adaptation, Psychological↗
PubMed1989

Occlusion pressures vs. micropipette pressures in the pulmonary circulation.

Because of the discrepancies between the arterial and venous occlusion technique and the micropuncture technique in estimating pulmonary capillary pressure gradient, we compared measurements made with the two techniques in the same preparations (isolated left lower lobe of dog lung). In addition, we also obtained direct and reliable measurements of pressures in 0.9-mm arteries and veins using a retrograde catheterization technique, as well as a microvascular pressure made with the double-occlusion technique. The following conclusions were made from dog lobes perfused with autologous blood at normal flow rate of 500-600 ml/min and pressure gradient of 12 mmHg. 1) The double-occlusion technique measures pressure in the capillaries, 2) a small pressure gradient (0.5 mmHg) exists between 30- to 50-micron arteries and veins, 3) a large pressure gradient occurs in arteries and veins greater than 0.9 mm, 4) the arterial and venous occlusion techniques measure pressures in vessels that are less than 900 microns diam but greater than 50 microns, very likely close to 100 microns, 5) serotonin constricts arteries (larger and smaller than 0.9 mm) whereas histamine constricts veins (larger and smaller than 0.9 mm). Thus three different techniques (small retrograde catheter, arterial and venous occlusion, and micropuncture) show consistent results, confirming the presence of significant resistance in large arteries and veins with minimal resistance in the microcirculation.

Animals↗
PubMed1988

Effect of uncouplers of oxidative phosphorylation on transmitter release in dystrophic mice.

Intracellular recording was used to study the effect of uncouplers of oxidative phosphorylation on miniature endplate potentials (m.e.p.p.s) in skeletal muscles from dystrophic mice and their clinically normal littermates. Control m.e.p.p. frequency in muscles from dystrophic mice was not significantly different from normal. In the presence of the inhibitors 2,4-dinitrophenol (10(-4) M) or guanidine (5 X 10(-3) M) m.e.p.p. frequency was increased less in muscles from dystrophic mice than that in muscles from normal littermates. In contrast, raising the extracellular calcium concentration, depolarising nerve terminals with potassium or motor nerve stimulation all caused a similar increase in m.e.p.p. frequency in normal and dystrophic muscles. It is suggested that there is a difference in the way in which calcium is stored in dystrophic nerve terminals but that their ability to regulate free calcium is normal.

Animals↗
PubMed1988

The effect of dissolved oxygen concentration on the growth physiology of Saccharomyces cerevisiae whi2 mutants.

Isogenic whi2 and WHI2+ strains of Saccharomyces cerevisiae were grown in a 2-litre bioreactor as batch cultures on a medium containing yeast extract and peptone with either glucose or ethanol as carbon and energy source. The concentration of dissolved oxygen within the medium was varied over the range of 0 to 100% saturation. Expression of the whi2 phenotype only occurred above 40% oxygen saturation with either glucose or ethanol as carbon and energy source. Under these conditions the whi2 cells could be distinguished from WHI2+ cells in that they were phase dark, highly budded and very small during the stationary growth phase, and reached final cell densities four to six times higher than WHI2+ cells. The results clearly show that the WHI2 gene of S. cerevisiae plays an important role in cell proliferation and that the availability of oxygen, or some product of oxidative metabolism, is involved in regulating the phenotypic expression of mutations within this gene.

Culture Media↗
PubMed1988

Pressure-time product, work rate, and endurance during resistive breathing in humans.

We examined the effect of increasing work rate, without a corresponding increase in the pressure-time product, on energy cost and inspiratory muscle endurance (Tlim) in five normal subjects during inspiratory resistive breathing. Tidal volume, mean inspiratory mouth pressure, duty cycle, and hence the pressure-time product were kept constant, whereas work rate was varied by changing the frequency of breathing. There was a linear decrease in Tlim of -2.1 +/- 0.5 s.J-1.min-1 (r = 0.87 +/- 0.06) with increasing work rate. The data satisfied a model of energy balance during fatiguing runs (Monod and Scherrer. Ergonomics 8: 329-337, 1965) and were consistent with the hypothesis that the rate of energy supply, or respiratory muscle blood flow, is fixed when the pressure-time product is constant. Our results indicate that during inspiratory resistive breathing against fatiguing loads, work rate determines endurance independently of the pressure-time product. On the basis of the model, our results lead to estimates of respiratory muscle blood flow and available energy stores under the conditions of our experiment.

Adult↗
PubMed1988

Pleural and extrapleural interstitial liquid pressure measured by cannulas and micropipettes.

In 15 anesthetized apneic, oxygenated rabbits we simultaneously measured pleural liquid and interstitial extrapleural parietal pressures by using catheters and/or cannulas and micropipettes connected to a servonull system. With the animal in lateral posture, at an average recording height of 4.4 +/- 0.9 (SD) cm from the most dependent part of the cavity, the extrapleural catheter and the pleural cannula yielded -2.5 +/- 0.6 and -5.5 +/- 0.2 cmH2O; the corresponding values for micropipette readings in the two compartments were -2.4 +/- 0.6 and -5.4 +/- 0.4 cmH2O, respectively (not significantly different from those measured with catheters and cannulas). In the supine animal, interstitial extrapleural catheter pressure data obtained at recording heights ranging from 15 to 80% of pleural cavity lay on the identity line when plotted vs. the micropipette pressure values simultaneously gathered from the same tissues. We conclude that 1) micropipettes and catheters-cannulas yield similar results when recording from the same compartment and 2) the hydraulic pressure in the parietal extrapleural interstitium is less negative than that in the pleural space.

Animals↗
PubMed1987

Norplant contraceptive implants: rods versus capsules.

Norplant contraceptive implants are silastic implants containing levonorgestrel. When placed subcutaneously in the medial aspect of the upper arm, they release low levels of levonorgestrel in a constant manner over an extended period of time. Comparative studies of two silastic rods versus six capsules containing levonorgestrel were studied in 250 subjects for 4,464 months of use. Only one pregnancy occurred during the study. Side effect patterns were similar in both groups; the major side effect being irregular uterine bleeding. The bleeding, however, was well tolerated by subjects in both groups and discontinuation rate was very low. The two-rod system offers the advantages of easier insertion technique and shorter insertion time as well as ease of removal as compared to the six-capsule system. Norplant contraceptive implants offer a highly effective means of contraception which is particularly suited for women who are concerned about failure and compliance with oral contraceptives. This type of contraception should become well accepted, not only in underdeveloped countries, but in developed countries as well.

Adolescent↗
PubMed1986

Respiratory and postural changes in intercostal muscle length in supine dogs.

In an attempt to assess the physiological function(s) of the external (E) and internal interosseous (I) intercostal muscles, we measured the changes in intercostal muscle length during spontaneous breathing, during passive inflation, and during passive rotation of the trunk. Studies were performed on 46 muscles from 16 supine anesthetized dogs, and changes in muscle length were assessed by sonomicrometry. The changes were small during spontaneous breathing, whether before or after bilateral phrenicotomy, and the pattern was variable among animals and among interspaces. The E, however, particularly in the lower interspaces, often lengthened with inspiration, and the I, in particular in the upper interspaces, often shortened with inspiration. Only occasionally did the E and I in one interspace change in length in opposing directions. This was also true during passive inflation, where both E and I usually shortened in the upper interspaces and lengthened in the lower interspaces. By contrast, during passive rotation of the trunk, the E and I systematically changed in length in opposing directions, and either muscle could successively lengthen and shorten a substantial amount depending on the side of rotation. These results suggest that 1) the E and I in supine dogs do not behave as antagonistic muscles during moderate respiratory efforts; and 2) they do behave as antagonistic muscles during rotation of the trunk. A primary function of these muscles as rotators of the trunk, unlike breathing, may explain why two layers of intercostal muscles with different fiber orientation exist between the ribs.

Animals↗
PubMed1986

Relationship between diaphragm length and abdominal dimensions.

We examined the relationship between changes in abdominal cross-sectional area, measured by respiratory inductive plethysmography, and changes in length in the costal and crural parts of the diaphragm, measured by sonomicrometry, in nine supine, anesthetized dogs. During passive inflation, both parts of the diaphragm shortened and abdominal cross-sectional area increased. During passive deflation, both parts of the diaphragm lengthened and abdominal cross-sectional area decreased. We subsequently used the relationship between costal and crural diaphragmatic length, respectively, and abdominal cross-sectional area during passive inflation-deflation to predict the length changes in the costal and crural diaphragm during quiet breathing before and after bilateral phrenicotomy. In the intact animal the inspiratory shortening in the crural diaphragm was almost invariably greater than predicted from the relationship during passive inflation. During inspiration after phrenicotomy the crural diaphragm invariably lengthened, whereas the costal diaphragm often shortened. In general there was a good correlation between the measured and predicted length change for the crural diaphragm (r = 0.72 before and 0.79 after phrenicotomy) and a poor one for the costal diaphragm (r = 0.05 before and 0.19 after phrenicotomy).

Abdomen↗
PubMed1986

Effect of breath holding on ventilation maldistribution during tidal breathing in normal subjects.

To test the hypothesis that during the course of a multiple-breath N2 washout (MBNW) diffusion-dependent ventilation maldistribution is more apparent in the early breaths, whereas convection-dependent maldistribution predominates in the later breaths, we performed MBNW with 0-, 1-, and 4-s end-inspiratory breath holds (BH0, BH1, BH4, respectively) in five normal subjects. Each subject breathed with a constant tidal volume of 1 liter, at 10-12 breaths/min and at constant flow rates. For each breath we computed the slope of the alveolar plateau normalized by the mean expired N2 concentration (Sn), the Bohr dead space (VDB), and an index analogous to the Fowler dead space (V50). In all five subjects, Sn, VDB, and V50 decreased with breath holding, indicating diffusion dependence of these indexes. Over the first five breaths the rate of increase of Sn as a function of cumulative expired volume (delta Sn/delta sigma VE) decreased by 29 and 54% during BH1 and BH4, respectively, compared with BH0. In contrast, from breath 5 to the end of the washout there was no significant change in delta Sn/delta sigma VE during BH1 and BH4 compared with BH0. Our results provide further experimental support for the hypothesis that the increase of Sn as a function of cumulative expired volume after the fifth breath constitutes a diffusion-independent index of ventilation inhomogeneity. It therefore reflects alveolar gas inequalities among larger units.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1986

Splenic hemangioma presenting as a "hot spot" on radiocolloid scintigraphy.

The appearance of a splenic hemangioma on radiocolloid scintigraphy has been reported to be that of a focal photon deficient lesion. We report a case of a patient who presented with the opposite appearance--that of a splenic "hot spot." We postulate that this appearance results from increased local blood flow presenting a greater proportion of colloid to the reticuloendothelial cells surrounding the hemangioma.

Adult↗