All-trans beta-carotene is absorbed preferentially to 9-cis beta-carotene, but the latter accumulates in the tissues of domestic ferrets (Mustela putorius puro)

The algae Dunaliella bardawil and Dunaliella salina naturally contain large concentrations of all-trans and 9-cis beta-carotene (betaC). The purpose of this study was to compare the relative serum and tissue accumulation of all-trans and 9-cis betaC in ferrets fed different ratios of all-trans/9-cis betaC derived from two commercial sources, D. bardawil or D. salina (Betatene). Male ferrets (7 wk old) were fed carotene-free, pelleted diets for 27 d. Beginning on d 18, groups of ferrets (n = 6 or 7) received daily, one of six oral supplements varying in ratios of 9-cis and all-trans betaC mixed with approximately 1.0mL of Ensure. Four supplements containing 5.2-8.3 micromol total betaC were prepared from a 20% Betatene preparation, D. bardawil, a high-cis Betatene preparation, and Betatene further enriched in 9-cis betaC with all-trans betaC/9-cis betaC ratios of 2.2, 1.5, 0.6 and 0.4, respectively. Two control supplements, high and low betaC, were prepared from commercial betaC beadlets. The high control supplement had an all-trans/9-cis ratio of 19.0, whereas 9-cis betaC was not detected in the low supplement. On d 27, serum and tissues were obtained for HPLC analysis of betaC and its isomers. Analysis of livers showed that all-trans betaC was the primary isomer present, but 9-cis and other isomers were also detected in all groups. The hepatic all-trans/9-cis ratios were 5.9, 4.9, 2.5, 1.4, 52.2 and47.5, respectively, for the groups listed above. Lower amounts of all-trans and 9-cis betaC were found in kidneys compared with the liver, but ratios of all-trans/9-cis were not different among groups. Only trace amounts of 9-cis betaC were found in serum. These results demonstrate that the algae D. bardawil and D. salina provide a bioavailable source of betaC isomers, but, as in humans, absorption of 9-cis betaC is poor and any 9-cis betaC absorbed is apparently cleared by the liver.     

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Ultrafiltration of lake water for potable water production

Ultrafiltration with coagulation or powdered activated carbon pretreatment is used to treat water from a public water supply. While UF without pretreatment is effective in removing turbidity, pretreatment prior to UF greatly enhances the removal of natural organic matter and trihalomethane precursors. Short-term flux loss can be minimized with backflushing, while long-term irreversible fouling seems to be affected most by the type of membrane polymer.     

Experiments of a prototype wind-driven reverse osmosis desalination system with feedback control

A prototype wind-powered reverse osmosis desalination system was constructed and tested on Coconut Island off the northern coast of Oahu, Hawaii, for brackish water desalination. The system has four major subsystems: a multi-vaned windmill/pump, a flow/pressure stabilizer, a reverse osmosis module, and a control mechanism. The feedback control mechanism, developed by this study, allowed this prototype system to be operated satisfactorily under mild ambient wind of 5 m/s or less. No auxiliary power source was needed. The system operational data showed that at an average wind speed of 5 m/s, brackish feedwater at a total dissolved solids concentration of 3000 mg/1 and at a flow rate of 13 1/min could be processed by this system. The average rejection rate of this prototype system was 97% and the average recovery ratio was 20%. The energy efficiency of the system was measured at 3 5%, which is comparable to the typical energy efficiency of well-operated multi-vaned windmills. Generally, the system's energy efficiency decreases as wind speed increases.     

Electro-optic high-resolution Fabry-Perot spectrometer

A single-crystal lithium niobate dtalon suitable for high-spectral-resolution studies has been operated successfully. This étalon with a 5-cm clear diameter and a gap equivalent to 2 cm in air has been found to have very linear response in wave number as a function of voltage. The combined advantages of adjustment-free operation, linearity in operation, and high luminosity in a small size (as a result of the μ(2) gain in the instrumental throughput caused by the large index of refraction of the lithium niobate substrate) make for a rugged instrument that is ideal for long-term unattended field operation.     

Non-insulin-dependent diabetes: from physiopathology to treatment

Non-insulin-dependent (or type 2) diabetes mellitus is a common, underdiagnosed and growing disease in our society. It is responsible for increased morbidity and mortality and represents an important public health problem. This polygenic disease is often expressed late in life and its evolution is accelerated by environmental factors leading to obesity. It combines defects in both insulin secretion and insulin action, and such defects are present in various proportions according to the type of patient and the stage of the disease. Diet and physical activity recommendations are the basis of the treatment. Current pharmacological approaches aim at improving insulin secretion and/or insulin cellular action. After secondary failure to oral drugs, insulin therapy should be initiated, the patient becoming "insulin-requiring". A synergy should be searched in the combination of various therapeutic modalities in order to improve the glycaemic control.     

A variety of epistatic interactions can occur between partially homologous transgene loci brought together by sexual crossing

Epistatic interactions between unlinked transgene loci in tobacco plants were studied following sexual crosses between different transgenic lines. Three potential "modifier" transgene loci, which were structurally similar but integrated at different chromosomal locations, were tested for their ability to influence the expression of a partially homologous "target" transgene locus. After introduction of an individual modifier locus, the target locus could be either unaffected, completely inactivated and methylated or differentially sensitive, showing more complete inactivation and methylation when homozygous than when hemizygous. The implications of these results for inbreeding depression in plants are discussed.