Smoking tobacco, oral snuff, and alcohol in the etiology of squamous cell carcinoma of the head and neck: a population-based case-referent study in Sweden

BACKGROUND: This case-referent study was conducted to elucidate the role of selected exogenous agents in the etiology of head and neck cancer. The factors studied were tobacco smoking, alcohol intake, the use of moist oral snuff, dietary factors, occupational exposures, and oral hygiene. In this first report, the authors discuss the impact of tobacco smoking, the use of oral snuff, and alcohol consumption. METHODS: The study base was approximately 2 million person-years at risk and consisted of Swedish males age 40-79 years living in 2 geographic regions during the years 1988-1990. A total of 605 cases were identified in the base, and 756 controls were selected by stratified random sampling from population registries covering the base. RESULTS: Among those who were tobacco smokers at the time of the study, the relative risk of head and neck cancer was 6.5% (95% confidence interval, 4.4-9.5%). After cessation of smoking, the risk gradually declined, and no excess risk was found after 20 years. The relative risk associated with alcohol consumption of 50 grams or more per day versus less than 10 grams per day was 5.5% (95% confidence interval, 3.1-9.6%). An almost multiplicative effect was found for tobacco smoking and alcohol consumption. CONCLUSIONS: Tobacco smoking and alcohol intake had a strong interactive effect on the risk of squamous cell carcinoma of the head and neck. Moderate alcohol intake (10-19 grams per day) had little or no effect among nonsmokers. No increased risk was found for the use of Swedish oral snuff.     

Control of Morphological and Rheological Properties of Carrot Cell Wall Particle Dispersions through Processing

A range of thermal and mechanical processes were used to create dispersions with different particle morphologies, i.e., systems that contain primarily plant cell wall clusters with an average particle size (d(0.5)) of ～200 µm, single cells ((d(0.5)?=?～70 µm) or cell fragments (d(0.5)?=?～40 µm). The small and large deformation rheology (viscoelastic properties and flow properties) of these dispersions, with a range of total solid contents covering textures varying from a fluid to a paste, were determined. The particle dispersions showed weak gel-like behaviour. Their elastic modulus (G′) as a function of total solid content exhibited three regions of different rheological behaviours. The particles formed particulate colloidal networks at relatively low solid content. The interaction of particles contributed to the sharp increase in the elastic modulus of the dispersion in the concentrated region. Further packing of particles beyond the critical packing volume fraction, caused the G′ for the ‘cluster-cell’ and the ‘single-cell’ dispersions to reach a plateau value. This is due to particle deformation resulting in changes in their microstructure and their ability to pack closely. Plant particle dispersions displayed abrupt yielding at the critical stress with a 3–4 order decrease in viscosity and high yield stress at low solids due to the formation of particulate colloidal network.     

Interactions between tocopherols,tocotrienols and carotenoids during autoxidation of mixed palm olein and fish oil

Electron spin resonance (ESR) and spin trapping detection of radical formation showed that the oxidative stability of palm olein/fish oil mixtures increased with the amount of palm olein. Mixtures with red palm olein were less stable than were mixtures with yellow palm olein. Addition of ascorbyl palmitate and citric acid gave further reduction of radical formation, whereas no effect was observed by adding lecithins. Storage of palm olein/fish oil mixtures (4:1) at 30 °C confirmed that red palm olein mixtures were less stable than were yellow palm olein mixtures. Ascorbyl palmitate together with citric acid improved the stability in both cases. The concentrations of α-tocopherol and α-tocotrienol decreased during storage, whereas β-, γ-, and δ-tocotrienols were unaffected. Ascorbyl palmitate reduced the losses of α-tocopherol and α-tocotrienol. The rate of loss of carotenoids was independent of the presence of fish oil and, except for an initial fast drop, also of the presence of ascorbyl palmitate.     

Antioxidant activity of rosemary and thyme by-products and synergism with added antioxidant in a liposome system

This study describes the use of liposomes as biological membrane models to evaluate the potential of natural antioxidants as inhibitors of lipid peroxidation. Antioxidative effects of by-products from manufacturing of essential oils, i.e., distilled rosemary leaf residues (DRL), distilled thyme leaf residues (DTL), and the combined antioxidative effects of DRL or DTL with α-tocopherol (TOH), ascorbic acid (AA), and quercetin (QC) on peroxidation of l-α-phosphatidylcholine liposomes as initiated by hydrophilic azo-initiators, were investigated. In addition, experiments were repeated with whole thyme leaves (TL) to compare the characteristics of by-products (leaf residues from distillation) with the initial industrial product (leaf for distillation). Extracts from DRL, DTL, and TL all had an obvious antioxidative effect as evidenced by a lag phase for the formation of phosphatidylcholine-derived conjugated dienes. DRL and DTL had similar antioxidative activity, while whole thyme leaves showed superior antioxidant activity compared with distilled thyme residues. Combination of TOH or QC with DRL, DTL, and TL, respectively, showed synergism in prolonging of the lag phase.     

Alkyl ether and enol ether analogs of (Z)-5-decenyl acetate,a pheromone component of the turnip moth,Agrotis segetum: probing a proposed bioactive conformation for chain-elongated analogs

In order to test a previous conclusion that chain-elongated analogs of (Z)-5-decenyl acetate(1), a pheromone component of the turnip moth,Agrotis segetum, adopt a loop conformation of the terminal alkyl chain in the bioactive conformation, a series of alkyl ether and enol ether analogs of1 and (Z)-5-dodecenyl acetate(2) have been synthesized and tested using singlecell electrophysiology. In these analogs a methylene group in positions 7 and 9 of1 and in positions 7 and 11 in2 have been replaced by an oxygen atom in order to energetically facilitate the formation of a loop conformation in the chain-elongated analogs. The electrophysiological results in combination with molecular mechanics (MM2 and MM3) calculated conformational energies show that the activity decreases of the chain-elongated ether analogs are significantly smaller than that for2 and that these activity decreases parallel the conformational energies for a loop formation of the terminal chains in the analogs. The results support our previous conclusion that the terminal chain of chain-elongated analogs of1 adopts a loop conformation in their bioactive conformations.     

Structure Studies on 6a-Thiathiophthenes and Related Compounds

The results from structure studies on 6a-thiathiophthenes show that different substituent groups perturb the bonding in the three-sulphur sequence to different degrees. Both equal and unequal S? S bonds occur in symmetrically as well as in unsymmetrically substituted derivatives. The specific effect of methyl and phenyl substituents on the sulphur-sulphur bonding may be described by the results from CNDO/2 calculations on mono-methyl and mono-phenyl substituted 6a-thiathiophthenes. Molecular packing and intermolecular close contacts also seem to affect the S? S bonding. The structures of equally substituted 6a-thiathiophthene analogues with and show, when compared with the equivalent 6a-thiathiophthene, that and cause a pronounced change in the S? S bonding, while the perturbation caused by is negligible. In symmetrical 6a-thiathiophthene analogues with and , the average bond length in the linear three-atom sequence is 9 – 12% longer than the respective single bond.     

Surface modifications of silicon nitride for cellular biosensor applications

Thin films of silicon nitride (Si₃N₄) can be used in several kinds of micro-sized biosensors as a material to monitor fine environmental changes related to the process of bone formation in vitro. We found however that Si₃N₄ does not provide optimal conditions for osseointegration as osteoblast-like MG-63 cells tend to detach from the surface when cultured over confluence. Therefore Si₃N₄ was modified with self-assembled monolayers bearing functional end groups of primary amine (NH₂) and carboxyl (COOH) respectively. Both these modifications enhanced the interaction with confluent cell layers and thus improve osseointegration over Si₃N₄. Furthermore it was observed that the NH₂ functionality increased the adsorption of fibronectin (FN), promoted cell proliferation, but delayed the differentiation. We also studied the fate of pre-adsorbed and secreted FN from cells to learn more about the impact of above functionalities for the development of provisional extracellular matrix on materials interface. Taken together our data supports that Si₃N₄ has low tissue integration but good cellular biocompatibility and thus is appropriate in cellular biosensor applications such as the ion-sensitive field effect transistor (ISFET). COOH and NH₂ chemistries generally improve the interfacial tissue interaction with the sensor and they are therefore suitable substrates for monitoring cellular growth or matrix deposition using electrical impedance spectroscopy.