Biomedical subjects

S H Kuhn

Publications and source records attributed to S H Kuhn.

5 recordsLinked to original sources

PubMed1984

Inhibition of human neutrophil elastase activity by encapsulated serum (Serumsome) therapy.

In order to inhibit human leukocyte proteolytic activity as a means of arresting the inflammatory response in tissues in vivo, we have designed a novel antiprotease carrier named serumsomes. Stabilized human serum was added to a flask containing a film of dried, purified lipids (phosphatidylcholine/dicetyl phosphate/cholesterol, 70:20:10) and hand-shaken for 10 min. Equal volumes of human neutrophils, and either serumsomes (in stabilized human serum) or stabilized human serum alone were mixed together. Following 2 h of incubation at 37 degrees C, the total elastase content of the neutrophils was reduced to 60 +/- 15% and 83 +/- 7% of the original activity by serumsomes and stabilized human serum, respectively. Analysis of beta-glucuronidase activity, a nonproteolytic lysosomal marker enzyme, revealed no diminution of activity during either of these incubations. These experiments demonstrate that human neutrophils are capable of interacting with serumsomes in vitro, selectively inhibiting the lysosomal protease elastase. By administering serumsomes in vivo, one may potentially preload blood leukocytes with serum antiproteases prior to their migration to inflammatory sites and thus possibly reduce the extent of tissue injury.

Capsules↗

PubMed1983

Interaction of liposomes with human leukocytes in whole blood.

The uptake of multilamellar liposomes into human leukocytes in whole blood in vitro was evaluated on the basis of the cellular association of liposomal markers (3H-labelled cholesterol, lipid phase; [14C]inulin, aqueous phase). The entry of liposomes into human blood leukocytes was linear for 60 min and was mediated by a saturable mechanism displaying affinity constants of 0.28 +/- 0.17 and 0.16 +/- 0.05 mM liposomal lipid (means +/- S.E.) for liposomal lipid and aqueous phase markers, respectively. Amicon filtration analysis of incubation mixtures containing blood and liposomes (phosphatidylcholine:dicetyl phosphate:cholesterol, 70:20:10) showed that 34% of [14C]inulin was lost (neither liposome-associated nor cell-associated) after 60 min. By preincorporating sphingomyelin (35 mol%) into multilamellar liposomes, the leakage of the model aqueous phase marker inulin was reduced to 8% after 60 min, thus enhancing the drug carrier potential of liposomes in blood. As a consequence of their interaction with liposomes, the polymorphonuclear leukocytes in whole blood decreased in apparent buoyant density, while maintaining their viability. These results indicate that blood leukocytes in their natural milieu of whole blood are capable of interacting with, and taking up multilamellar liposomes.

Biological Transport, Active↗

PubMed1983

Biochemical and morphologic changes in rabbit lung following endotracheal instillation of zymosan particles.

In order to establish a model of lung disease in which the usefulness of potential antiinflammatory compounds can be evaluated, we have analyzed the biochemical and cellular responses of rabbits to zymosan deposition in their lungs. A suspension of zymosan particles was instilled into the lungs of rabbits using an intratracheal catheter. Because the influx of leukocytes and the transudation of plasma into affected lungs was expected to contribute to the total cellular enzyme and protein levels, lungs were homogenized and assayed after various time intervals for six cellular enzymes and for protein content. After one day, alkaline phosphatase and neutral protease levels were elevated by 90% and 50%, respectively, above normal values. After two and three days, all of the pulmonary enzymes assayed displayed maximal two- to fourfold increases in their levels of activity. After seven days, only the alkaline phosphatase and neutral protease levels remained slightly elevated by 50% and 30%, respectively. Histologic analysis revealed focal and diffuse intraalveolar, interstitial, peribronchiolar, and perivascular accumulations of macrophages, granulocytes, and lymphocytes. Severe pulmonary edema, evident microscopically after one to three days, correlated well with 100% increases in both the wet weight and protein content of the lungs. In control experiments, the intratracheal infusion of saline solution minus zymosan particles resulted in a variety of enzymatic changes in the lungs after three days, which could be distinguished both enzymatically and histologically from those following zymosan deposition; histopathologic analysis revealed a pattern of intravascular congestion with erythrocytes, edematous thickening of alveolar septa, and focal intraalveolar hemorrhages, but with no inflammatory infiltration. In summary, this study demonstrates the time course of an experimental model for acute and chronic lung inflammation, the extent of which may be quantitatively evaluated using cellular enzymatic markers.

Animals↗

PubMed1981

Liposome uptake by human leukocytes. Enhancement of entry mediated by human serum and aggregated immunoglobulins.

The entry of immunoglobulin-coated liposomes into human leukocytes bearing Fc receptors was evaluated using two methods: (i) the cellular association of liposomal markers (3H-labelled phosphatidylcholine, lipid phase; [14C]inulin, aqueous phase), and (ii) the ultrastructural cytochemistry of cells following incubation of cells with liposomes containing a cytochemical marker (horseradish peroxidase) in the aqueous spaces. The entry of liposomes into a cell population composed predominantly of neutrophils was linear for 10--15 min and was mediated by an active process that appeared to be both energy- and surface-dependent. This uptake could be largely inhibited by incubation at 0 degrees C, and by exposure to glutaraldehyde, iodoacetamide, N-ethylmaleimide, and an excess of aggregated immunoglobulins. Entry into cells of multilamellar liposomes was saturable, displaying affinity constants of 1.1 and 1.7 mM. Ultrastructural analysis of the heterogeneous leukocyte population showed that monocytes took up liposomes more actively than neutrophils and lymphocytes. Moreover, liposomes were almost always found within the leukocytes, rather than adherent to the outer plasma membrane. The relative avidity of monocytes was confirmed by comparing the uptake of radiolabelled liposomes by a 'pure' neutrophil population, a 'mixed' neutrophil population, and a 'mononuclear cell' population. Precoating liposomes with high molecular weight aggregates of human immunoglobulin G resulted in enhanced serum-independent uptake. The fraction of aggregated immunoglobulin G which was most effective in provoking uptake of coated liposomes also stimulated the greatest amount of lysosomal enzyme secretion. These data suggest that the interaction (precoating) of liposomes with either high molecular weight aggregates of immunoglobulin G or with serum enhances their subsequent uptake by human leukocytes.

Blood Proteins↗

PubMed1977

The need to repeat lumbar puncture.

Four patients with bacterial meningitis are reported. On initial examination 1 patient had a slightly abnormal cerebrospinal fluid (CSF), and in the other 3 patients the CSF was completely normal. An obviously purulent CSF was obtained when lumbar puncture was repeated 14-48 hours later. All 4 patients presented initially with pyrexia, and either neck stiffness or convulsions. In 3 of the 4 patients a cause for pyrexia was found on initial examination but lumbar punctures were done for neck stiffness or convulsions to exclude meningitis. The problems and the need to repeat a lumbar puncture, as well as the importance of blood cultures in a patient with suspected meningitis, are discussed. The fact that a normal specimen of CSF does not exclude meningitis is stressed.

Cerebrospinal Fluid↗