Resin-like Material Research Articles

Investigation into Propolis Components Responsible for Inducing Skin Allergy: Air Oxidation of Caffeic Acid and Its Esters Contribute to Hapten Formation.

Propolis is a resin-like material produced by bees from the buds of poplar and cone-bearing trees and is used in beehive construction. Propolis is a common additive in various biocosmetics and health-related products, despite the fact that it is a well-known cause of contact allergy. Caffeic acid and its esters have been the primary suspects behind the sensitization potency of propolis-induced contact allergy. However, the chemical structures of the protein adducts formed between these haptens and skin proteins during the process of skin sensitization remain unknown. In this study, the reactivity of three main contact allergens found in propolis, namely, caffeic acid (CA), caffeic acid 1,1-dimethylallyl ester (CAAE), and caffeic acid phenethyl ester (CAPE), was investigated. These compounds were initially subjected to the kinetic direct peptide reactivity assay to categorize the sensitization potency of CA, CAAE, and CAPE, but the data obtained was deemed too unreliable to confidently classify their skin sensitization potential based on this assay alone. To further investigate the chemistry involved in generating possible skin allergy-inducing protein adducts, model peptide reactions with CA, CAAE, and CAPE were conducted and analyzed via liquid chromatography-high-resolution mass spectrometry. Reactions between CA, CAAE, and CAPE and a cysteine-containing peptide in the presence of oxygen, both in closed and open systems, were monitored at specific time points. These studies revealed the formation of two different adducts, one corresponding to thiol addition to the α,β-unsaturated carbonyl region of the caffeic structure and the second corresponding to thiol addition to the catechol, after air oxidation to o-quinone. Observation of these peptide adducts classifies these compounds as prehaptens. Interestingly, no adduct formation was observed when the same reactions were performed under oxygen-free conditions, highlighting the importance of air oxidation processes in CA, CAAE, and CAPE adduct formation. Additionally, through NMR analysis, we found that thiol addition occurs at the C-2 position in the aromatic ring of the CA derivatives. Our results emphasize the importance of air oxidation in the sensitization potency of propolis and shed light on the chemical structures of the resultant haptens which could trigger allergic reactions in vivo.

Study of the reproductive biology of an Amazonian Heterotaxis (Orchidaceae) demonstrates the collection of resin-like material by stingless bees

Tropical and subtropical plants provide to pollinators a range of nutritive and non-nutritive materials as alternative to pollen and nectar, including resins, which are gathered by females of several groups of social and solitary bees. Although resin-like material has previously been recorded in Maxillariinae, these investigations generally did not present data relating to pollinators. In fact, the collection of resins has never been recorded elsewhere in orchids. The aim of this paper was to provide a detailed study of the reproductive biology of an Amazonian Heterotaxis, H. superflua, based on records of flowering phenology, floral morphology, pollinator behavior and breeding system. Heterotaxis superflua offers resin-like material to pollinators and is pollinated by a single species of stingless bee. The resin is a heterogeneous material rich in mucilage, starch and sugars, while lipoidal substances occur as small droplets. Chemical analyses confirm the presence of sugar, which explain the presence of reducing sugars and mucilage detected in the histochemical investigations. Our data also showed the Heterotaxis is self-compatible and pollinator dependent. This study demonstrates for the first time the collection of resin-like material in orchids. The gathering of resin is frequently associated with the nest construction, since this material is considered to be a water-repellent and has anti-pathogen chemical properties. Despite offering of a floral reward, fruit set under natural conditions is lower than for experimental pollinations, suggesting limited pollen flow within the population.

Brazilian green propolis suppresses acetaminophen-induced hepatocellular necrosis by modulating inflammation-related factors in rats.

Propolis is a resin-like material produced by honey bees from bud exudates and sap of plants and their own secretions. An ethanol extract of Brazilian green propolis (EEBGP) contains prenylated phenylpropanoids and flavonoids and has antioxidative and anti-inflammatory effects. Acetaminophen (N-acetyl-p-aminophenol; APAP) is a typical hepatotoxic drug, and APAP-treated rats are widely used as a model of drug-induced liver injury. Oxidative stress and inflammatory reactions cause APAP-induced hepatocellular necrosis and are also related to expansion of the lesion. In the present study, we investigated the preventive effects of EEBGP on APAP-induced hepatocellular necrosis in rats and the protective mechanism including the expression of antioxidative enzyme genes and inflammation-related genes. A histological analysis revealed that administration 0.3% EEBGP in the diet for seven days reduced centrilobular hepatocellular necrosis with inflammatory cell infiltration induced by oral administration of APAP (800 mg/kg) and significantly reduced the area of necrosis. EEBGP administration did not significantly change the mRNA expression levels of antioxidant enzyme genes in the liver of APAP-treated rats but decreased the mRNA expression of cytokines including Il10 and Il1b, with a significant difference in Il10 expression. In addition, the decrease in the mRNA levels of the Il1b and Il10 genes significantly correlated with the decrease in the percentage of hepatocellular necrosis. These findings suggest that EEBGP could suppress APAP-induced hepatocellular necrosis by modulating cytokine expression.

Nectaries and male-biased nectar production in protandrous flowers of a perennial umbellifer Angelica sylvestris L. (Apiaceae)

Nectar is the most common floral pollinator reward. In dichogamous species, floral nectar production rates can differ between sexual phases. We studied the structure of nectaries located on the stylopodium and nectar production in protandrous umbellifer Angelica sylvestris. Our study species produced nectar in both floral sexual phases. Nectar sugar concentration was low (on average 22 ± 11 %, mean ± SD) and the nectar hexose rich and composed of sucrose, glucose, fructose and a small amount of amino acids, including β-alanine, a non-protein amino acid. Although nectar composition and sugar concentration varied little between floral sexual phases, nectar production showed a threefold reduction during the stigma receptive period. This is in contrast to other studies of Apiaceae that have reported female-biased nectar production, but in the direction predicted by plant sexual selection theory, suggesting that in pollen-unlimited species, floral rewards mainly enhance male reproductive success. The structure of the nectary was similar at the two sexual stages investigated, and composed of a secretory epidermis and several layers of nectariferous and subsecretory parenchyma. The nectary cells were small, had large nuclei, numerous small vacuoles and dense, intensely staining cytoplasm with abundant endoplasmic reticulum, mitochondria and secretory vesicles. They contained abundant resin-like material that may potentially act as defence against microbes. Starch was rarely observed in the nectary cells, occurring predominantly at the female stage and mainly in guard and parenchyma cells in close proximity to stomata, and in subsecretory parenchyma. The main route of nectar release in A. sylvestris seems to be via modified stomata.

Sinusitis maxilar iatrogénica tras la colocación de implantes: A propósito de un caso

Perforation of the floor of the maxillary sinus or nasal cavity during implant placement in the residual bone located below is not an infrequent situation. It's been strongly reported that slight membrane puncture while preparing implant bed does not play a significant role in clinical outcome, as it heals spontaneously, but it is an essential requirement that the implant remains intraoperatory stable. We present the case of a 54 yr. old woman that consulted in our office referring permanent cacosmia and halitosis associated to sporadic episodes of pain and purulent rhinorrhea, that didn't ease to the administration of several different antibiotics. Radiological findings show three dental implants in the first quadrant replacing teeth 1.2, 1.3 and 1.6: first one piercing the nostril and the third one with its apical end completely into the right maxillary sinus with a delimitated radiopaque mass associated. Once confirmed the existency of an oroantral fistula and its involvement in the two-year evolution chronic sinusitis diagnosed, the treatment established included the extraction of the three implants and the simultaneous osseous reconstruction with an autologous bone chin graft. After the removal of implant 1.6, a composite resin-like material is found stuck to its surface with supposedly retentive purposes, contributing in this way in a very strong way to increase irritation. Remanent defect is so important that makes impossible bone grafting in this area, so we proceed to curette harmed sinusal mucosa, sending a sample for histological evaluation, and close with a Bichat fat pad pedicled flap. Postoperatory follow-up and evolution was favourable, achieving total remission of sympthomatology and complete recovery.

Comparative histology of floral elaiophores in the orchids Rudolfiella picta (Schltr.) Hoehne (Maxillariinae sensu lato) and Oncidium ornithorhynchum H.B.K. (Oncidiinae sensu lato)

Floral elaiophores, although widespread amongst orchids, have not previously been described for Maxillariinae sensu lato. Here, two claims that epithelial, floral elaiophores occur in the genus Rudolfiella Hoehne (Bifrenaria clade) are investigated. Presumed elaiophores were compared with those of Oncidiinae Benth. and the floral, resin-secreting tissues of Rhetinantha M.A. Blanco and Heterotaxis Lindl., both genera formerly assigned to Maxillaria Ruiz & Pav. (Maxillariinae sensu stricto). Putative, floral elaiophore tissue of Rudolfiella picta (Schltr.) Hoehne and floral elaiophores of Oncidium ornithorhynchum H.B.K. were examined by means of light microscopy, histochemistry, scanning electron microscopy and transmission electron microscopy. Floral, epithelial elaiophores are present in Rudolfiella picta, indicating, for the first time, that oil secretion occurs amongst members of the Bifrenaria clade (Maxillariinae sensu lato). However, whereas the elaiophore of R. picta is borne upon the labellar callus, the elaiophores of O. ornithorhynchum occur on the lateral lobes of the labellum. In both species, the elaiophore comprises a single layer of palisade secretory cells and parenchymatous, subsecretory tissue. Cell wall cavities are absent from both and there is no evidence of cuticular distension in response to oil accumulation between the outer tangential wall and the overlying cuticle in R. picta. Distension of the cuticle, however, occurs in O. ornithorhynchum. Secretory cells of R. picta contain characteristic, spherical or oval plastids with abundant plastoglobuli and these more closely resemble plastids found in labellar, secretory cells of representatives of Rhetinantha (formerly Maxillaria acuminata Lindl. alliance) than elaiophore plastids of Oncidiinae. In Rhetinantha, such plastids are involved in the synthesis of resin-like material or wax. Despite these differences, the elaiophore anatomy of both R. picta (Bifrenaria clade) and O. ornithorhynchum (Oncidiinae) fundamentally resembles that of several representatives of Oncidiinae. These, in their possession of palisade secretory cells, in turn, resemble the floral elaiophores of certain members of Malpighiaceae, indicating that convergence has occurred here in response to similar pollination pressures.

Microbial activity in an acid resin deposit: Biodegradation potential and ecotoxicology in an extremely acidic hydrocarbon contamination

Acid resins are residues produced in a recycling process for used oils that was in use in the forties and fifties of the last century. The resin-like material is highly contaminated with mineral oil hydrocarbons, extremely acidic and co-contaminated with substituted and aromatic hydrocarbons, and heavy metals. To determine the potential for microbial biodegradation the acid resin deposit and its surroundings were screened for microbial activity by soil respiration measurements. No microbial activity was found in the core deposit. However, biodegradation of hydrocarbons was possible in zones with a lower degree of contamination surrounding the deposit. An extreme acidophilic microbial community was detected close to the core deposit. With a simple ecotoxicological approach it could be shown that the pure acid resin that formed the major part of the core deposit, was toxic to the indigenous microflora due to its extremely low pH of 0–1.

The synthesis and vibrational spectra of fluorosulfate derivatives of titanium, zirconium and hafnium

The syntheses of the binary fluorosulfates, Zr(SO 3F) 4 and Hf(SO 3F) 4, by oxidation of the corresponding metalpowders with bis(fluorosulfuryl) peroxide, S 2O 6F 2, in fluorosulfuric acid, HSO 3F, are described. The resulting products are white hygroscopic solids which are not sufficiently soluble in HSO 3F to allow electrical conductivity and NMR studies or Hammett acidity function ( H 0) determinations in order to evaluate their use as Lewis acids in conjugate superacid systems. Oxidation of titanium under similar conditions resulted in the formation of a greenish-yellow resin-like material of limited thermal stability with the approximate composition Ti(SO 3F) 4. However, infrared spectra indicated the presence of small amounts of HSO 3F. In addition, the solvolysis of ZrCl 4 in an excess of HSO 3F at 25 °C has been investigated as a potential route to Zr(SO 3F) 4. The results indicate that short reaction times of 1–2 d yielded incompletely substituted products of the approximate composition ZrCl x ,(SO 3F) 4−x ( x = 0.22), while prolonged reaction times of 3–4 weeks gave rise to partially decomposed materials of approximate composition ZrO 0.5F 1.5(SO 3F) 1.5. The ability of all three tetrakis(fluorosulfato) metallates to act as SO 3F − ion acceptors is evident from the isolation of thermally stable salts of the composition Cs 2[M(SO 3F) 6] (M=Ti, Zr or Hf) when the metal oxidation was carried out in the presence of 2 mol equiv. of CsSO 3F. All the materials were characterized by their vibrational spectra, which are extremely similar and closely resemble those of previously reported cesium hexakis(fluorosulfato) metallates.

High TC Superconductor Fibers from Metallo-Organic Precursors

AbstractHomogeneous solution for Y-Ba-Cu-0 superconductor was prepared from yttrium i-propoxide, barium i-propoxide, and copper ethylhexanoate. The solution was converted to a resin-like material and was readily dissolved in organic solvents. The resin possesses a cohesive property in a number of solvents, such as benzene and xylene. Single-phase superconducting YBa2Cu307_x fibers have been continuously spun from the viscous solution. Controlled amounts of Y2BaCu05 phase in the fibers were made possible by slight adjustments in the solution compositions. Partial substitution of copper ethylhexanoate with copper trifluoroacetate prevents barium carbonate formation In the fiber during curing and organic pyrolysis.

Nature of Tasmanian oil shale

Since deposition, the organic matter of most oil shales has been so changed over geological time that little recognisable features remain. Microscopical examination does not provide much help for constitutional analysis and thus one cannot use biological features as a basis for classification. Tasmanite oil shale is a notable exception. The kerogen is so sharply differentiated from the mineral matrix that it can be largely separated by mechanical means. Tasmanite kerogen, when isolated, appears as flattened discs, which, by various sectioning processes, can be shown to have been nearly spherical in shape before compaction. There has been a great deal of argument as to the exact nature of these dissemenules. The century-old suggestion, originally rejected, that they are algal in origin has now been generally accepted and it may be taken that Tasmanites, as it occurs in oil shale, represents the cyst stage of a peculiar alga belonging, most likely, to the Chlorophyceae. The exact relationship within the family is still uncertain. Because of its discrete and peculiar structure, it might be assumed that the organic matter of tasmanite has a chemistry different from other algal shales. This is true only in so far as the soluble resin-like material is concerned, the pyrolysate possesses a normal hydrocarbon chemistry, although the non-hydrocarbon constituents are somewhat more than usual. Infrared and other physical methods of analysis support this hypothesis.