Optical rotatory power, biaxiality, and models of chiral tilted smectic phases.

Among the chiral tilted smectics, the stable existence has been confirmed in numerous investigations of SmC(*)(A), (antiferroelectric smectic-C(A)) SmC(*)(F11) (SmC(*)(gamma)), SmC(*)(F12) (antiferroelectric, AF) and SmC* phases. The structures of the ferrielectric SmC(*)(F11) and SmC(*)(F12) phases suggested by different models are essentially different although all the models use the three-layer and four-layer periodicity for them. The structures of the phases were investigated using the optical rotatory power (ORP) measurements technique. The ORP was simulated using Berreman's 4 x 4-matrix method. The compound under investigation (S)-1-methylheptyl 4-(4(')-n-undecyloxy-biphenyl-4-yl-carbonyloxy) [acronym (S)-11OF1M7] clearly provides SmC(*)(F11) and SmC(*)(F12) phases, the temperature range for the existence of these phases is about 5 degrees C each. This had not been achieved for the earlier investigated antiferroelectric liquid crystal (AFLC) samples. The results obtained confirm that the unit cell of the molecular structure of these subphases is highly biaxial. Due to the biaxiality the texture of the homeotropic cell under a polarizing microscope appears nonuniform. This requires a special approach to the measurements and a simulation of the ORP, which is discussed in detail. A technique has been designed where the transmitted intensity through a polarizing microscope is measured as a function of the angle of polarization of the incident light. From the observed output, which is a biased sine wave, the ORP is being determined. In the same scan, the wavelength of light is also being automatically altered. Comparing the simulated and measured data, we can conclude that in the SmC(*)(F12) phase the distortion angle of the directors in the Ising model is lower than 10 degrees. Using the Ising model, the pitch in SmC(*)(F11) has been determined and this is found to have a strong temperature dependence.

The neuronal distribution of cannabinoid receptor type 1 in the trigeminal ganglion of the rat.

Cannabinoid compounds have been shown to produce antinociception and antihyperalgesia by acting upon cannabinoid receptors located in both the CNS and the periphery. A potential mechanism by which cannabinoids could inhibit nociception in the periphery is the activation of cannabinoid receptors located on one or more classes of primary nociceptive neurons. To address this hypothesis, we evaluated the neuronal distribution of cannabinoid receptor type 1 (CB1) in the trigeminal ganglion (TG) of the adult rat through combined in situ hybridization (ISH) and immunohistochemistry (IHC). CB1 receptor mRNA was localized mainly to medium and large diameter neurons of the maxillary and mandibular branches of the TG. Consistent with this distribution, in a de facto nociceptive sensory neuron population that exhibited vanilloid receptor type 1 immunoreactivity, colocalization with CB1 mRNA was also sparse (<5%). Furthermore, very few neurons (approximately 5%) in the peptidergic (defined as calcitonin gene-related peptide- or substance P-immunoreactive) or the isolectin B4-binding sensory neuron populations contained CB1 mRNA. In contrast, and consistent with the neuron-size distribution for CB1, nearly 75% of CB1-positive neurons exhibited N52-immunoreactivity, a marker of myelinated axons. These results indicate that in the rat TG, CB1 receptors are expressed predominantly in neurons that are not thought to subserve nociceptive neurotransmission in the noninjured animal. Taken together with the absence of an above background in situ signal for CB2 mRNA in TG neurons, these findings suggest that the peripherally mediated antinociceptive effects of cannabinoids may involve either as yet unidentified receptors or interaction with afferent neuron populations that normally subserve non-nociceptive functions.

Lectin-mediated interactions of surfactant protein D with alveolar macrophages.

Surfactant protein D (SP-D) is a calcium-dependent carbohydrate-binding protein that is secreted into the pulmonary airspaces by type II epithelial and Clara cells. Previous studies have shown that SP-D can bind to specific surfactant phospholipids and to glycoconjugates associated with the surface of various microorganisms, consistent with possible roles in surfactant metabolism and pulmonary host defense. We now describe specific saccharide-mediated interactions of SP-D with alveolar macrophages in lung tissue and in vitro. Biotinylated rat SP-D showed specific binding to alveolar macrophages in sections of rat lung; this labeling was inhibited by competing saccharides or EDTA. In addition, the binding of 125I-SP-D to isolated alveolar macrophages in the presence of calcium was time-dependent, saturable, and reversible and was preferentially inhibited by known monosaccharide and disaccharide ligands for SP-D. Scatchard analysis gave an apparent single class of binding sites with a Kd = 1.4 x 10(-6) M. We speculate that the multivalent structure of SP-D mediates bridging interactions between microbial glycoconjugates or surfactant phospholipids and specific glycosylated ligands expressed on the surface of phagocytic cells.

Surfactant protein D: subcellular localization in nonciliated bronchiolar epithelial cells.

Surfactant protein D (SP-D, CP4) is a collagenous surfactant-associated carbohydrate binding protein that was initially characterized as a biosynthetic product of type II pneumocytes. Immunoperoxidase studies of formaldehyde solution-fixed and paraffin-embedded rat lung demonstrated staining for SP-D in the cytoplasm of a subpopulation of bronchiolar epithelial cells as well as type II cells. Accordingly, immunogold-labeling techniques were used to further examine the cellular distribution and subcellular localization of SP-D in the small airways. Lung tissues were fixed with 0.5% glutaraldehyde-3% paraformaldehyde and embedded in LR White resin. Sections were reacted with affinity purified polyclonal antibodies to SP-D, and sites of antibody binding were demonstrated using a biotinylated secondary antibody-streptavidin-gold detection system. Anti-SP-D selectively decorated secretory compartments of nonciliated bronchiolar cells (Clara cells) with strong and specific labeling of apical electron-dense secretory granules. Almost all of the granules in nonciliated columnar cells were labeled; however, labeling was typically nonuniform, with preferential decoration of the periphery of the granule. The largest numbers of immunoreactive epithelial cells were observed in the distal membranous bronchioles, with progressively smaller numbers of cells in more proximal bronchioles. There was no detectable labeling of cells lining the large cartilagenous airways or trachea. These studies provide evidence that SP-D is a secretory product of nonciliated bronchiolar cells. We suggest that Clara cell-derived SP-D is a component of bronchiolar lining material, consistent with our hypothesis that SP-D contributes to surfactant metabolism and/or host defense within small airways.

Extracellular matrix protein gene expression in atherosclerotic hypertensive pulmonary arteries.

Lobar pulmonary arteries from patients with unexplained pulmonary hypertension were obtained at the time of single-lung transplantation to determine the response of large elastic vessels to increased intraluminal pressure. Specifically, human pulmonary arteries were examined to determine if remodeling remained active at the time of surgery and whether remodeling was similar to previously reported remodeling observed in several animal models. Grossly, the hypertensive vessels appeared atherosclerotic. Histochemical stains revealed a thick, diffuse neointima in hypertensive vessels compared with normal vessels. Immunohistochemistry demonstrated elastin protein in the neointima and in situ hybridization studies demonstrated tropoelastin mRNA largely in the neointima. Similarly, immunohistochemistry and in situ hybridization detected cellular fibronectin, thrombospondin and type I collagen protein and mRNA within the thickened intima from hypertensive vessels. These studies provide evidence that hypertensive vessels in patients with severe chronic pulmonary hypertension are actively remodeling but that the pattern of remodeling is different from previously described animal models.

Surfactant protein D. Increased accumulation in silica-induced pulmonary lipoproteinosis.

Surfactant protein D (SP-D) (CP4) is a collagenous surfactant-associated carbohydrate binding protein that is synthesized and secreted by alveolar epithelial cells. Previous studies have shown that intratracheal administration of crystalline silica to rats elicits a marked increase in the alveolar accumulation of surfactant lipids and surfactant protein A (SP-A). The authors examined the accumulation of SP-D using this animal model of alveolar proteinosis. Immunoperoxidase localization of SP-D studies at 2 weeks after silica instillation showed intense staining of intra-alveolar exudates, and cytoplasmic staining of hypertrophic type II cells. Immunoelectron microscopy showed that airspace SP-D was specifically associated with granular material, but not tubular myelin or other membranous structures. SP-D was quantified in bronchoalveolar lavage by immunoassay using antibodies specific for SP-D, and by reversephase HPLC after affinity purification of SP-D on maltosyl-agarose. Within 2 weeks after silica instillation, there was a greater than 45-fold increase in lavage SP-D per lung compared with saline controls, including an almost ten-fold increase in the insoluble or surfactant-associated protein. These studies indicate that the extracellular accumulation of SP-D is markedly increased in silica-induced lipoproteinosis, and that SP-D is associated with amorphous components identified by electron microscopy.

Developmental expression of pulmonary surfactant protein D (SP-D).

Surfactant protein D (SP-D) is a collagenous, surfactant-associated, carbohydrate-binding protein that is synthesized by pulmonary epithelial cells. In the present studies, we examined the expression of SP-D and SP-D mRNA during late fetal (day 17, 19, 21) and early postnatal (day 5) rat lung development using immunochemical, cell-free translation, and Northern hybridization assays. SP-D mRNA and immunoreactive SP-D protein were first detected in guanidine extracts of whole rat lung at 21 days of gestation and reached even higher concentrations during the postnatal period. Likewise, immunoperoxidase studies of rat lung using affinity-purified antibodies to SP-D showed no staining at day 17 or 19, but demonstrated strong cytoplasmic staining of cuboidal epithelial cells lining immature airspaces at day 21 and strong cytoplasmic staining of type II and nonciliated bronchiolar cells in adult lung. SP-D also appeared in amniotic fluid by day 21 and was partially purified by affinity chromatography on maltosyl-agarose under conditions used for the isolation of rat lung SP-D. These studies indicate that the production of SP-D is increased shortly prior to birth, and that the increases in total lung SP-D and SP-D mRNA are temporally correlated with SP-D secretion and the appearance of SP-D in amniotic fluid.