Cerebroside sulfotransferase activity in human lung tissues. An elevated level in lung adenocarcinoma.

Cerebroside sulfotransferase activity was demonstrated in particulate fractions from human lung and its carcinoma tissues. The activity in human lung adenocarcinoma was significantly higher than those in a different histological type of carcinoma (squamous cell carcinoma) and in normal tissue from which each carcinoma was derived.     

Purification and properties of lung lectin. Rat lung and human lung beta-galactoside-binding proteins.

Lung is one of the organs of the rat with a particular abundance of haemagglutinating activity that is inhibited by beta-galactosides. This lectin activity can be attributed to a single protein that has been purified from rat lung; a similar protein has been purified from human lung. The molecular weights and subunit structures were estimated from gel filtration and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis; the human lung lectin appeared to be composed to two identical subunits, mol.wt. 14500, whereas rat lung lectin was observed as both a dimer and a tetramer of one subunit type, mol.wt. 13500. Both lectins bind to disaccharides or oligosaccharides with terminal beta-linked galactose residues. The carbohydrate moiety may be free [lactose or D-galactopyranosyl-beta-(1 leads to 4)-thiogalactopyranoside], protein-bound (asialofetuin) or lipid-bound (cerebrosides). The molecular properties of the beta-galactoside-binding proteins of rat lung and human lung are closely similar to those of embryonic chick muscle lectin [Nowak, Kobiler, Roel & Barondes (1977) Proc. Natl. Acad. Sci. U.S.A. 73, 1383--1387] and calf heart lectin [De Waard, Hickman & Kornfeld (1976) J. Biol. Chem. 251, 7581--7587].     

Oxygen radicals in lung pathology.

Pulmonary tissue can be damaged in different ways, for instance by xenobiotics (paraquat, butylated hydroxytoluene, bleomycin), during inflammation, ischemia reperfusion, or exposure to mineral dust or to normobaric pure oxygen levels. Reactive oxygen species are partly responsible for the observed pulmonary tissue damage. Several mechanisms leading to toxicity are described in this review. The reactive oxygen species induce bronchoconstriction, elevate mucus secretion, and cause microvascular leakage, which leads to edema formation. Reactive oxygen species even induce an autonomic imbalance between muscarinic receptor-mediated contraction and the beta-adrenergic-mediated relaxation of the pulmonary smooth muscle. Vitamin E and selenium have a regulatory role in this balance between these two receptor responses. The autonomic imbalance might be involved in the development of bronchial hyperresponsiveness, occurring in lung inflammation. Finally, several antioxidants are discussed which may be beneficial as therapeutics in several lung diseases.     

Characterization of VAMP‐2 in the lung: implication in lung surfactant secretion

Lung surfactant is crucial for reducing the surface tension of alveolar space, thus preventing the alveoli from collapse. Lung surfactant is synthesized in alveolar epithelial type II cells and stored in lamellar bodies before being released via the fusion of lamellar bodies with the apical plasma membrane. SNAREs (soluble N‐ethylmaleimide‐sensitive fusion protein‐attachment protein receptors) play an essential role in membrane fusion. We have previously demonstrated the requirement of t‐SNARE (target SNARE) proteins, syntaxin 2 and SNAP‐23 (N‐ethylmaleimide‐sensitive factor‐attachment protein 23), in regulated surfactant secretion. Here, we characterized the distribution of VAMPs (vesicle‐associated membrane proteins) in rat lung and alveolar type II cells. VAMP‐2, ?3 and ?8 are shown in type II cells at both mRNA and protein levels. VAMP‐2 and ?8 were enriched in LB (lamellar body) fraction. Immunochemistry studies indicated that VAMP‐2 was co‐localized with the LB marker protein, LB‐180. Functionally, the cytoplasmic domain of VAMP‐2, but not VAMP‐8 inhibited surfactant secretion in type II cells. We suggest that VAMP‐2 is the v‐SNARE (vesicle SNARE) involved in regulated surfactant secretion.     

Dipeptidyl peptidase IV in the human lung and spinocellular lung cancer.

The isoelectric point and proportions of soluble and membrane bound dipeptidyl peptidase IV (DPP-IV) in human lung and spinocellular lung cancer tissue were tested. It was found that soluble DPP-IV is relatively less frequent in the cancer than in normal lung tissue. We demonstrated multiple molecular forms of DPP-IV in normal and cancer lung tissues, differing probably not only in the degree of sialylation. DPP-IV from lung cancer tissue consists of more basic molecular forms than that from normal lung tissue. These results suggest that the molecular properties of DPP-IV in normal and cancerous lung tissues may be different.     

Sound transmission in the lung as a function of lung volume.

We were interested in how the transmission of sound through the lung was affected by varying air content in intact humans as a method of monitoring tissue properties noninvasively. To study this, we developed a method of measuring transthoracic sound transit time accurately. We introduced a "coded" sound at the mouth and measured the transit time at multiple microphones placed over the chest wall by using a 16-channel lung sound analyzer (Stethographics). We used a microphone placed over the neck near the trachea as our reference and utilized cross-correlation analysis to calculate the transit times. The use of the coded sound, composed of a mix of frequencies from 130 to 150 Hz, greatly reduced the ambiguity of the cross-correlation function. The measured transit time varied from 1 ms at the central locations to 5 ms at the lung bases. Our results also indicated that transit time at all locations decreased with increasing lung volume. We found that these results can be described in terms of a model in which sound transmission through the lung is treated as a combination of free-space propagation through the trachea and a propagation through a two-phase system in the parenchyma.