Preindustrial 14CH4 indicates greater anthropogenic fossil CH4 emissions.

Atmospheric methane (CH4) is a potent greenhouse gas, and its mole fraction has more than doubled since the preindustrial era1. Fossil fuel extraction and use are among the largest anthropogenic sources of CH4 emissions, but the precise magnitude of these contributions is a subject of debate2,3. Carbon-14 in CH4 (14CH4) can be used to distinguish between fossil (14C-free) CH4 emissions and contemporaneous biogenic sources; however, poorly constrained direct 14CH4 emissions from nuclear reactors have complicated this approach since the middle of the 20th century4,5. Moreover, the partitioning of total fossil CH4 emissions (presently 172 to 195 teragrams CH4 per year)2,3 between anthropogenic and natural geological sources (such as seeps and mud volcanoes) is under debate; emission inventories suggest that the latter account for about 40 to 60 teragrams CH4 per year6,7. Geological emissions were less than 15.4 teragrams CH4 per year at the end of the Pleistocene, about 11,600 years ago8, but that period is an imperfect analogue for present-day emissions owing to the large terrestrial ice sheet cover, lower sea level and extensive permafrost. Here we use preindustrial-era ice core 14CH4 measurements to show that natural geological CH4 emissions to the atmosphere were about 1.6 teragrams CH4 per year, with a maximum of 5.4 teragrams CH4 per year (95 per cent confidence limit)-an order of magnitude lower than the currently used estimates. This result indicates that anthropogenic fossil CH4 emissions are underestimated by about 38 to 58 teragrams CH4 per year, or about 25 to 40 per cent of recent estimates. Our record highlights the human impact on the atmosphere and climate, provides a firm target for inventories of the global CH4 budget, and will help to inform strategies for targeted emission reductions9,10.

Protective effect of melatonin against gentamicin ototoxicity.

OBJECTIVE: To research the protective effect of melatonin against gentamicin ototoxicity. METHODS: Guinea pigs were randomly divided into four groups. The first group received intramuscular gentamicin (120 mg/kg body weight/day) for 17 days. Over the same time period, a second group simultaneously received intramuscular gentamicin (120 mg/kg body weight/day) plus (on the other side) intramuscular melatonin (0.3 ml kg body weight/day). Two groups of controls were treated for 17 days with either intramuscular melatonin or intramuscular saline. After the 17 days, each animal underwent distortion product otoacoustic emission testing (both ears). The guinea pigs were sacrificed by decapitation just after the final injection. Their cochleae were used to produce a tissue section, surface preparation and scanning electron microscope preparation. RESULTS: Distortion product otoacoustic emission testing indicated gentamicin-induced hearing loss at 3, 4, 6 and 8 kHz in gentamicin-treated animals. Animals receiving melatonin co-therapy had significantly attenuated hearing loss and their cochleae showed lower rates of outer hair cell loss (comparing the same cochlear turns), compared with gentamicin-treated animals (p < 0.01). CONCLUSION: These findings confirm the occurrence of outer hair cell loss after gentamicin treatment, and the attenuation of such loss following simultaneous melatonin injection, using the method of morphological evaluation. These results suggest that melatonin protects against gentamicin ototoxicity by interfering with cytotoxic mechanisms.

[Explanation for "Jin Shuo Yin Kai" in Ben cao gang mu shi yi (Supplements to compendium of materia medica)].

The entry of "Jin Shuo Yin Kai" included in volume 7 of Ben Cao Gang Mu Shi Yi refers to Adiantum flabellulatum L. Fagopyrum cymesum Meisn, and polygenum penfoliatum L. respectively.

[Clinical and experimental study on effect of Chanbei Kechuanping in treating bronchial asthma].

OBJECTIVE: To observe the clinical effect of Chanbei Kechuanping (CBKCP) on bronchial asthma and to explore its mechanism. METHODS: Ninety-six patients of bronchial asthma were randomly divided into two groups, the CBKCP treated group and the control group (treated by Guilong Kechuanning). The changes on symptoms and signs of asthma, pulmonary function, T-lymphocyte subsets, plasma soluble interleukin-2 receptor (sIL-2R), thromboxane B2(TXB2) and 6-keto-prostaglandin F1 alpha(6-keto-PGF1 alpha) were observed before and after treatment. RESULTS: (1) The markedly effective rate and effective rate in the CBKCP treated group were higher than those in the control group. The pulmonary function, including 1 second forced expiratory volume, maximum expiratory flow rate and forced lung expiratory vital capacity were all improved in both groups, but the effect was more obvious in the CBKCP treated group. (2) As compared with the control group, CBKCP showed more obvious effect in lowering sIL-2R, T-lymphocyte subset and raising 6-keto-PGF1 alpha. Experimental study of guinea pig with asthma model showed that CBKCP could markedly prolong the latent time of asthma attack, lower the percentage of mast cells in total cells in the alveoli lavage solution, blood acidophic cell count and degranulation rate of mast cells, and decrease IgE, IL-4 and TXB2 levels as well as increase the 6-keto-PGF1 alpha level. CONCLUSION: CBKCP has favorable therapeutic effect on asthma attack, it might play the role partly by regulating the functional T-lymphocyte subsets, reducing the level of IgE, sIL-2R, IL-4 and TXB2, and increasing the level of 6-keto-PGF1 alpha.

[Biological characteristics of Cryptoporus volvatus (peck) Hubb., a medicinal fungus].

Through ecological investigations and experimental studies, it has been shown that C. volvatus is a fungus growing on decaying matter; the carbon source of culture medium comes from glucose, honey, fructose, mannitol, etc; and its nitrogen source from peptone, yeast powder, etc. The best ratio of carbon to nitrogen (C/N) is 20-25: 1, optimum pH 5.5-6.5 and optimal temperature 25-30 degrees C.

Heteronuclear 2D NMR studies of an engineered insulin monomer: assignment and characterization of the receptor-binding surface by selective 2H and 13C labeling with application to protein design.

Insulin provides an important model for the application of genetic engineering to rational protein design and has been well characterized in the crystal state. However, self-association of insulin in solution has precluded complementary 2D NMR study under physiological conditions. We demonstrate here that such limitations may be circumvented by the use of a monomeric analogue that contains three amino acid substitutions on the protein surface (HisB10----Asp, ProB28----Lys, and LysB29----Pro); this analogue (designated DKP-insulin) retains native receptor-binding potency. Comparative 1H NMR studies of native human insulin and a series of three related analogues--(i) the singly substituted analogue [HisB10----Asp], (ii) the doubly substituted analogue [ProB28----Lys; LysB29----Pro], and (iii) DKP-insulin--demonstrate progressive reduction in concentration-dependent line-broadening in accord with the results of analytical ultracentrifugation. Extensive nonlocal interactions are observed in the NOESY spectrum of DKP-insulin, indicating that this analogue adopts a compact and stably folded structure as a monomer in overall accord with crystal models. Site-specific 2H and 13C isotopic labels are introduced by semisynthesis as probes for the structure and dynamics of the receptor-binding surface. These studies confirm and extend under physiological conditions the results of a previous 2D NMR analysis of native insulin in 20% acetic acid [Hua, Q. X., & Weiss, M. A. (1991) Biochemistry 30, 5505-5515]. Implications for the role of protein flexibility in receptor recognition are discussed with application to the design of novel insulin analogues.