Cognitive ability at age 11 and 70 years, information processing speed, and APOE variation: The Lothian Birth Cohort 1936 study.

The e4 allele of the apolipoprotein E (APOE) gene confers risk of Alzheimer's disease and, in some studies, relates to cognitive ability and decline in older people without Alzheimer's disease. Its relationship with processing speed, a contributor to cognitive decline with age, is largely unknown. This study tests the association of APOE with cognition and speed, with and without covarying childhood mental ability. The 1,013 participants were tested on cognitive ability at age 11 as part of the Scottish Mental Survey of 1947 and, at age 70, were tested on reasoning, working memory, information processing speed, and executive function. The results showed that APOE was associated with the general cognitive factor, 2 nonverbal tests, and choice reaction time (RT) variability; as expected, the e4 allele was the risk allele. RT measures and a general speed factor were nonlinearly related to APOE when factoring childhood ability (p     

Effect of aeration and pH on gramicidin S production by Bacillus brevis

Although the biosynthesis of the antibiotic gramicidin S (GS) by Bacillus brevis ATCC 9999 has been studied extensively, almost no attention has been given to environmental control of its fermentation process. In this respect, GS fermentations conducted in a 7.5 dm³ fermentor in complex (YP) medium revealed that a high aeration rate resulted in a high biomass yield (12 g DCW dm^?3) with very low GS levels (170 mg GS dm^?3). Lowering the aeration rate (5 dm³ air min^?1 at 300 rev min^?1) caused a dramatic increase in GS formation (2100 mg GS dm^?3) and comparable but slower biomass formation. In chemically-defined (F3/6) medium fermentations, an aeration rate of 5 dm³ air min^?1 at 300 rev min^?1 was apparently too high as only 0.104 mg GS mg^?1 DCW was produced. A much lower aeration rate (2 dm³ air min^?1 at 250 rev min^?1) was needed to arrive at a higher specific antibiotic level: 0.130 mg GS mg^?1 DCW. These data seem compatible with the finding that oxygen is known to inactivate the GS-synthetases. Furthermore, keeping the pH constant at 7.3 under low aeration conditions increased specific GS production up to 0.220 mg GS mg^?1 DCW in YP, as well as in F3/6 fermentations. Both environmental pH and dissolved oxygen tension clearly affect growth pattern, growth extent and GS production in these high yielding media. These data stress the importance of controlling pH and aeration rate during GS fermentations.     

Cyclic voltammetry on lead electrodes in sulphuric acid solution

The oxidation of lead in 5 M H₂SO₄ was studied by cyclic voltammetry. When a potential scan is applied from /t-1.0 V to 2.6 V vs. R.H.E. the PbSO₄/PbO₂ oxidation peak can be observed in the anodic voltammogram provided the scan rate is 0.16 mV/s or lower. When the potential scan is restricted to the potential range +0.6 V to +2.6 V the anodic voltammogram shows two peaks which were assigned to the formation of α-PbO₂ and β-PbO₂ respectively. This β-PbO₂ is formed underneath the PbSO₄ film. During the reverse sweep the main reduction peak at 1.65 V corresponds with the reduction of β-PbO₂ to PbSO₄. α-PbO₂ is not reduced at a definite potential but it is reduced to n-PbO·PbSO₄ with n increasing from the oxide-electrolyte interface towards the interior of the electrode and with more cathodic potential. At potentials below 0 V, the basic lead sulphates are reduced.The effect of the addition of small amounts of H₃PO₄ to the H₂SO₄ electrolyte during the potential scanning results in an increase of the α-PbO₂ peak and a disappearance of the β-PbO₂ peak.