Effect of caffeine and reduced temperature (20 degrees C) on the organization of the pre-Golgi and the Golgi stack membranes

In the present study we have dissected the transport pathways between the ER and the Golgi complex using a recently introduced (Kuismanen, E., J. J?ntti, V. M?kiranta, and M. Sariola. 1992. J. Cell Sci. 102:505-513) inhibition of transport by caffeine at 20 degrees C. Recovery of the Golgi complex from brefeldin A (BFA) treatment was inhibited by caffeine at reduced temperature (20 degrees C) suggesting that caffeine inhibits the membrane traffic between the ER and the Golgi complex. Caffeine at 20 degrees C did not inhibit the BFA-induced retrograde movement of the Golgi membranes. Further, incubation of the cells in 10 mM caffeine at 20 degrees C had profound effects on the distribution and the organization of the pre-Golgi and the Golgi stack membranes. Caffeine treatment at 20 degrees C resulted in a selective and reversible translocation of the pre- and cis-Golgi marker protein (p58) to the periphery of the cell. This caffeine-induced effect on the Golgi complex was different from that induced by BFA, since mannosidase II, a Golgi stack marker, remained perinuclearly located and the Golgi stack coat protein, beta-COP, was not detached from Golgi membranes in the presence of 10 mM caffeine at 20 degrees C. Electron microscopic analysis showed that, in the presence of caffeine at 20 degrees C, the morphology of the Golgi stack was altered and accumulation of numerous small vesicles in the Golgi region was observed. The results in the present study suggest that caffeine at reduced temperature (20 degrees C) reveals a functional interface between the pre-Golgi and the Golgi stack.     

Assay conditions for the mitochondrial NADH:coenzyme Q oxidoreductase

The assay of Complex I activity requires the use of artificial acceptors, such as short-chain coenzyme Q homologs and analogs, because the physiological quinones, such as CoQ10, are too insoluble in water to be added as substrates to the assay media. The medical interest raised in the last years on the pathological changes of Complex I activity has focussed on the requirement of easy reliable assays for its analysis. We have undertaken a systematic examination of the assay conditions of Complex I in mitochondrial membranes, using a series of quinones as electron acceptors, particularly the coenzyme Q homologs CoQ0, CoQ1 and CoQ2, and the analogs duroquinone and decylubiquinone. Our findings have pointed out that the most suitable electron acceptor for the NADH:CoQ reductase assay is the homolog CoQ1. The analog DB, commercially available, although yielding a high activity, nevertheless causes some problems for the standardization of the assay conditions.     

Work-site smoking policies: their population impact in Washington State

This article presents data from a population-based, random-digit dialing telephone survey of 1228 employed adults in Washington State, conducted 1989 through 1990. Eighty-one percent of men and 91% of women reported work-site smoking restrictions. Employees in work sites with no-smoking policies were less likely to be current smokers; men in work sites with policies restricting smoking smoked fewer cigarettes on both workdays and nonworkdays. Forty-eight percent of male and 53% of female smokers reported reduced smoking as a result of work-site policy. Work-site smoking policies, intended to protect against smoke exposure, may also reduce employee smoking.     

Treatment of hemifacial spasm with botulinum toxin

We injected botulinum toxin to treat hemifacial spasm, and investigated the effects and the patient's impression of this treatment. Average duration of improvement lasted about 3.5 months in both the initial treatment group and the recurrent group. However the patients in the recurrent group received fewer units of botulinum toxin than those in the initial treatment group. Except for local paralysis that disappeared within a month, there were very few complications. Most patient were satisfied with this treatment. We conclude that the treatment of hemifacial spasm with botulinum toxin is both simple and useful.     

Hypomethylation of classical satellite DNA and chromosome instability in lymphoblastoid cell lines

To determine possible relationships between DNA hypomethylation and chromosome instability, human lymphoblastoid cell lines from different genetic constitutions were studied with regard to 1) uncoiling and rearrangements, which preferentially affect the heterochromatic segments of chromosomes 1 and 16; 2) the methylation status of the tandemly repetitive sequences (classical satellite and alphoid DNAs) from chromosomes 1 and 16, and of the L1Hs interspersed repetitive sequences. The methylation status largely varied from cell line to cell line, but for a given cell line, the degree of methylation was similar for all the repetitive DNAs studied. Two cell lines, one obtained from a Fanconi anemia patient and the other from an ataxia telangiectasia patient were found to be heavily hypomethylated. The heterochromatic segments of their chromosomes 1 and 16 were more frequently elongated and rearranged than those from other cell lines, which were found to be less hypomethylated. Thus, in these lymphoblastoid cell lines, alterations characterized by uncoiling and rearrangements of heterochromatic segments from chromosomes 1 and 16 seem to correlate with the hypomethylation of their repetitive DNAs. Two-color in situ hybridizations demonstrated that these elongations and rearrangements involved only classical satellite-DNA-containing heterochromatin. This specificity may be related to the excess of breakages affecting the chromosomes carrying these structures in a variety of pathological conditions.     

All-optical wavelength conversion by semiconductor opticalamplifiers

Following a brief introduction to the applications for wavelength conversion and the different available conversion techniques, the paper gives an in depth analysis of cross gain and cross phase wavelength conversion in semiconductor optical amplifiers. The influence of saturation filtering on the bandwidth of the converters is explained and conditions for conversion at 20 Gb/s or more are identified. The cross gain modulation scheme shows extinction ratio degradation for conversion to longer wavelengths. This can be overcome using cross phase modulation in semiconductor optical amplifiers that are integrated into interferometric structures. The first results for monolithic integrated interferometric wavelength converters are reviewed, and the quality of the converted signals is demonstrated by transmission of 10 Gb/s converted signals over 60 km of nondispersion shifted single mode fiber