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Biomedical subjects

S Kelly

Publications and source records attributed to S Kelly.

At least 217 records · Page 12Linked to original sources
PubMed1982

The proton translocating ATPase responsible for urinary acidification.

H+ secretion by the turtle urinary bladder is produced by a proton pump located in the luminal membrane. We show that a microsomal fraction of these cells contains an electrogenic proton translocating ATPase that is inhibited by dicyclohexylcarbodiimide but not oligomycin or vanadate. On a sucrose density gradient, this ATPase co-migrated with luminal membranes labeled with concanavalin A, but was separate from a lysosomal marker. This enzyme is therefore the H+ ATPase that causes urinary acidification.

Adenosine Triphosphatases↗
PubMed1982

Gas mixing in the lungs of dogs and pigs.

We performed single breath washouts in 14 dogs and 4 pigs using a gas mixture containing 5% helium (He) and 5% sulphur hexafluoride (SF6) with, and without, an end inspiratory breathhold. In dogs, the slope of the alveolar plateau was steeper for SF6 than for He, the difference decreasing after 20 sec of breathholding. In contrast, in pigs there was no difference between the two slopes although both were steeper than in dogs. Following a 15-sec breathhold, both slopes decreased, that of the He plateau becoming significantly flatter than that for SF6. Furthermore, the expirate became relatively SF6 enriched. The results indicate that in pigs the mechanism responsible for the sloping alveolar plateau is not diffusion dependent, and hence cannot be due to 'stratification'. Neither do the results support diffusive interaction within an asymmetrical acinus as a basis for the slope. Our findings suggest that the latter is due to sequential emptying of relatively large units subtended by a branch point in which gas transport is entirely convective.

Animals↗
PubMed1982

Chest wall mechanics in dogs with acute diaphragm paralysis.

To investigate the action of the inspiratory intercostals, we studied the patterns of rib cage and abdominal motion during tidal breathing in eight dogs before and after bilateral phrenicotomy. Hooks screwed into the sternum and the ribs were used to monitor the anteroposterior and transverse diameters of the rib cage and the axial displacements of the sternum and the ribs. In all animals, we found that during tidal inspirations performed with the inspiratory intercostals alone, 1) the rib cage moved outward while the abdomen moved inward; 2) the rib cage was displaced near its relaxation curve (defined by a plot of its transverse vs. anteroposterior diameter) but expanded more in its transverse than in its anteroposterior dimension; and 3) the ribs in the midaxillary line moved cephalad, whereas the sternum was displaced caudally. Additional experiments performed on four dogs demonstrated that contraction of the parasternal intercostals was responsible for the inspiratory caudal displacement of the sternum. These findings indicate that in the dog, 1) the inspiratory intercostals act essentially on the lateral walls of the rib cage, and 2) those of the parasternal area produce a caudal displacement of the sternum. In addition, they suggest strongly that the axial displacement of the sternum constitutes an additional degree of freedom of motion of the rib cage and that contraction of the neck accessory muscles is mandatory for the sternum to be displaced in a cephalad direction during inspiration.

Animals↗
PubMed1980

Isolation of ribonuclease-free polysomes from human placenta.

Human placenta is known to have a high level of polysome-bound ribonuclease which has hindered the isolation of intact polyribosomes from this tissue. We describe conditions for preparing polysomes devoid of apparent ribonuclease activity from both first trimester and term placenta. This stable preparation was achieved by utilizing buffer at low pH containing 300 mM LiCl and precipitating the polysomes chemically with 200 mM MgCl2. The yield of polysomes obtained by this procedure is 2-2.5 fold greater than that obtained by the conventional method of preparing placental polysomes. The polysomes are considered pure as judged by the ratios of absorbance 260/280 and 260/235. Moreover, the yield of polysomes obtained is greater than 95% of the tissue content and the profile of the polysomes is probably representative of the in vivo population. This is concluded from experiments in which a known amount of labelled chick polysomes was added to fresh placental tissue and the recovery of label and its distribution was analyzed.

Cell Fractionation↗
PubMed1980

Metabolic pathways coupled to H+ transport in turtle urinary bladder.

Active H+ transport in the turtle urinary bladder is mediated by an ATPase. Although the source of ATP is usually mitochondrial oxidative phosphorylation, it is possible because of intracellular compartmentalization or cellular heterogeneity that one metabolic pathway exclusively provides ATP to the pump. To examine this we performed several types of experiments. In one, the coupling between the rate of transport and the rate of oxidation of 14C-labeled substrates was studied. We found that there was coupling between H+ transport and glucose, butyrate oleate, and beta-OH-butyrate oxidation. In another set of experiments we depleted turtle bladders of their endogenous substrates and tested the effect of a number of substrates on the rate of transport. We found that glucose, pyruvate, lactate, actetate, butyrate and beta-OH butyrate all stimulated H+ transport. In a third set of experiments we found no coupling between H+ transport and lactate production. Finally, we found that reduction of H+ transport by mucosal acidification resulted in an increase in epithelial cell ATP concentrations and a decrease in ADP levels. These results suggest that the H+ pump receives its ATP from carbohydrate and fatty acid oxidation. The changes in ATP and ADP levels provide an initial explanation for the coupling of H+ transport to the rate of cellular oxidative metabolism.

Adenine Nucleotides↗
PubMed1979

Fluorimetric assay of acid lipase in human leukocytes.

A fluorimetric assay for leukocyte acid lipase, the enzyme defect in Wolman disease, is described. The method requires a smaller volume of blood and can be performed more rapidly than the present colorimetric assay for the leukocyte enzyme.

Clinical Enzyme Tests↗