The course of development of mania in patients with recurrent depression

The authors attempted to assess the extent to which bipolar patients are misdiagnosed as unipolar by evaluating the development of mania in patients who had recognized bipolar illness and by means of follow-up data on patients who had recurrent depressions. Mania occurred early in the course of bipolar illness: almost 80% of the bipolar patients were initially hospitalized for mania. Follow-up data and theoretically based calculations suggest that the chance of a patient with recurrent depressions becoming bipolar is about 5%. Based on these findings, the authors make suggestions for the classification of unipolar patients.     

Quantum-cascade laser measurements of stratospheric methane and nitrous oxide

A tunable quantum-cascade (QC) laser has been flown on NASA's ER-2 high-altitude aircraft to produce the first atmospheric gas measurements with this newly invented device, an important milestone in the QC laser's future planetary, industrial, and commercial applications. Using a cryogenically cooled QC laser during a series of 20 aircraft flights beginning in September 1999 and extending through March 2000, we took measurements of methane (CH(4)) and nitrous oxide (N(2)O) gas up to ~20 km in the stratosphere over North America, Scandinavia, and Russia. The QC laser operating near an 8-mum wavelength was produced by the groups of Capasso and Cho of Bell Laboratories, Lucent Technologies, where QC lasers were invented in 1994. Compared with its companion lead salt diode lasers that were also flown on these flights, the single-mode QC laser cooled to 82 K and produced higher output power (10 mW), narrower laser linewidth (17 MHz), increased measurement precision (a factor of 3), and better spectral stability (~0.1 cm(-1) K). The sensitivity of the QC laser channel was estimated to correspond to a minimum-detectable mixing ratio for methane of approximately 2 parts per billion by volume.     

Single-mode tunable quantum cascade lasers in the spectral range ofthe CO2 laser at λ=9.5-10.5 μm

Widely tunable, single-mode quantum cascade distributed feedback (QC-DFB) lasers based on a complex coupling scheme and operating in the wavelength range of the CO₂ laser (λ≈9.5-10.5 μm) are reported. Dynamic single-mode emission up to high current levels is obtained. The continuous single-mode tuning range is 150 nm, while the tuning range of the equivalent Fabry-Perot laser is ~400 nm. By homogeneously reducing all layer thicknesses by 10%, the wavelength coverage of a single QC-laser design can be extended to cover one entire regular band of the fundamental CO₂ laser spectrum     

Prolactin alters the expression of integumental glycoconjugates in the red-spotted newt, Notophthalmus viridescens

Prolactin (PRL)-mediated changes in the texture and secretory activity of the skin in adult red-spotted newts may involve alterations in the distribution and/or expression of structural and secretory epidermal glycoconjugates. To explore this possibility, skin samples were obtained from groups of conditioned animals that had received injections of either ovine prolactin or amphibian saline over a 14-day period. Glycoconjugates within the epidermis and cutaneous glands were examined by means of lectin histochemistry using a panel of eight HRP-labelled lectins. PRL increased levels of sialic acid and n-acetylglucosamine in the stratum corneum. In contrast, glycoconjugates containing fucose, galactose, n-acetylgalactosamine, and galactose-(1,3)-n-acetylgalactosamine were decreased by PRL within both glands and epidermis. These results suggest that the integumental effects associated with prolactin in the red-spotted newt are mediated, at least in part, through the alteration of epidermal and glandular glycoconjugates.     

Stress activated cytokines and the heart

The ability of myocardium to successfully compensate for, and adapt to, stress ultimately determines whether the heart will decompensate and fail, or whether it will instead maintain preserved function. Despite the importance of the myocardial response to environmental stress, very little is known with respect to the biochemical mechanisms that are responsible for mediating and integrating the stress response in the heart. In the present review we will summarize recent experimental material which suggests that cytokines that are expressed within the myocardium in response to a environment injury, namely tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) and interleukin-6 (IL-6), may play an important role in initiating and integrating homeostatic responses within the heart. However, these 'stress-activated' cytokines all have the potential to produce cardiac decompensation when expressed at sufficiently high concentrations. Accordingly, the theme that will emerge from this discussion is that the short-term expression of stress-activated cytokines within the heart may provide the heart with an adaptive response to stress, whereas long-term expression of these molecules may be frankly maladaptive by producing cardiac decompensation.     

Metabolism of short-chain ceramide and dihydroceramide analogues in Chinese hamster ovary (CHO) cells

A series of radiolabelled ceramides (D-erythro and L-threo) and dihydroceramides (DL-erythro and DL-threo) with 2, 4 or 6 carbon N-acyl groups were synthesized. These analogues were incubated with cultured CHO cells and radioactive products isolated and analyzed. In addition to synthesis of short-chain sphingomyelin and glucosylceramide, radiolabelled sphingosine and sphinganine were released from short-chain ceramides and dihydroceramides and subsequently utilized for synthesis of long-chain ceramide and sphingolipids. Substrate preference for short-chain sphingomyelin synthesis in cells was D-erythro-ceramides > L-threo-ceramides > DL-erythro-dihydroceramides > DL-threo-dihydroceramides, and C4- and C6-analogues were preferred over the C2-analogue. Kinetic constants for conversion of short-chain (dihydro)ceramides to short-chain sphingomyelin were determined using CHO cell membranes and found to correlate with substrate preference in cultured cells. D-erythro-C6-Ceramide was the preferred substrate for short-chain glucosylceramide synthesis. D-erythro-C2-ceramide inhibited incorporation of [3H]serine into sphingomyelin, glucosylceramide and ceramide rapidly (2 h) and in a dose-dependent manner. Over a similar time period, [3H]choline-labelling of sphingomyelin was not affected. Inhibition of [3H]serine-labelling of sphingolipids appeared to correlate with release of [3H]long-chain bases from short-chain ceramides and dihydroceramides and synthesis of long-chain sphingolipids. However, some discrepancies between DL-erythro-C4- and C6-dihydroceramides, and D-erythro-C2-ceramide suggested that short-chain dihydroceramides were less efficient in suppressing de novo synthesis from [3H]serine, while contributing substantially to endogenous sphingolipid synthesis. Inhibition of de novo sphingolipid synthesis by short-chain ceramides and dihydroceramides could not be related to inhibition of serine palmitoyltransferase activity in vitro.