Regulation of lung endothelin content by the glucocorticosteroid budesonide.

Intratracheal instillation of Sephadex beads induced a long-lasting inflammation in the rat lung as seen by an increase in lung weights. Repeated instillation enhanced this reaction and increased lung endothelin-1 content 3.5 times. Budesonide given s.c. abolished these effects and even reduced basal endothelin-1 content by 72%. The tissue content of the sensory neuropeptide neurokinin A were unaffected by both treatments. Endothelin has been proposed to play a part in the pathogenesis of bronchial asthma. If it is so, the ability of budesonide to reduce endothelin-1 content could thus be added to the list of beneficial effects of glucocorticosteroids in these conditions.     

Fine Mapping the Spatial Distribution and Concentration of Unlabeled Drugs within Tissue Micro-Compartments Using Imaging Mass Spectrometry

Readouts that define the physiological distributions of drugs in tissues are an unmet challenge and at best imprecise, but are needed in order to understand both the pharmacokinetic and pharmacodynamic properties associated with efficacy. Here we demonstrate that it is feasible to follow the in vivo transport of unlabeled drugs within specific organ and tissue compartments on a platform that applies MALDI imaging mass spectrometry to tissue sections characterized with high definition histology. We have tracked and quantified the distribution of an inhaled reference compound, tiotropium, within the lungs of dosed rats, using systematic point by point MS and MS/MS sampling at 200 µm intervals. By comparing drug ion distribution patterns in adjacent tissue sections, we observed that within 15 min following exposure, tiotropium parent MS ions (mass-to-charge; m/z 392.1) and fragmented daughter MS/MS ions (m/z 170.1 and 152.1) were dispersed in a concentration gradient (80 fmol-5 pmol) away from the central airways into the lung parenchyma and pleura. These drug levels agreed well with amounts detected in lung compartments by chemical extraction. Moreover, the simultaneous global definition of molecular ion signatures localized within 2-D tissue space provides accurate assignment of ion identities within histological landmarks, providing context to dynamic biological processes occurring at sites of drug presence. Our results highlight an important emerging technology allowing specific high resolution identification of unlabeled drugs at sites of in vivo uptake and retention.     

Endorphin mediated increase in pain threshold induced by long-lasting exercise in rats

Rats were trained to run spontaneously, without stress, in running wheels. The running activity increased gradually and could reach a plateau of 7 km/night after 3–4 weeks. During the first hour of running in the dark phase the squeak threshold increased significantly and remained high in the morning. The degree of increased threshold was correlated to the amount of running activity. The squeak threshold declined during the following 6 hours of inactivity. A rapid decrease in threshold occurred after naloxone (1–2 mg/kg i.p.). It is suggested that long-lasting muscle exercise (e.g. jogging), acupuncture, and low frequency electrical stimulation of afferent nerve fibres produce discharges in muscle afferents which influence central endorphin mechanics giving analgetic effects.     

Habitat deterioration promotes the evolution of direct development in metamorphosing species

Although metamorphosis is widespread in the animal kingdom, several species have evolved life-cycle modifications to avoid complete metamorphosis. Some species, for example, many salamanders and newts, have deleted the adult stage via a process called paedomorphosis. Others, for example, some frog species and marine invertebrates, no longer have a distinct larval stage and reach maturation via direct development. Here we study which ecological conditions can lead to the loss of metamorphosis via the evolution of direct development. To do so, we use size-structured consumer-resource models in conjunction with the adaptive-dynamics approach. In case the larval habitat deteriorates, individuals will produce larger offspring and in concert accelerate metamorphosis. Although this leads to the evolutionary transition from metamorphosis to direct development when the adult habitat is highly favorable, the population will go extinct in case the adult habitat does not provide sufficient food to escape metamorphosis. With a phylogenetic approach we furthermore show that among amphibians the transition of metamorphosis to direct development is indeed, in line with model predictions, conditional on and preceded by the evolution of larger egg sizes.     

Ordination and classification of operational geographic units in Southwest Sweden

The vascular plant distributions of Dalsland and northern Bohuslän (Southwest Sweden) were subjected to multivariate analyses in order to delimit geographically coherent floristic zones. 271 squares of 5×5 km were the Operational Geographic Units; the data matrix comprises presence/absence species records for each OGU. Different ordination and classification methods were tested and detailed results are presented for detrended correspondence analysis (DCA), UPGMA and ordination space partitioning (OSP). A weighting procedure, neighbour-weighting, which gives pseudo-frequency scores along the nominal scale 0–9 depending on the species' distribution patterns, is introduced. The superior method for delimiting geographically coherent floristic zones was judged to be ordination space partitioning, using DCA and neighbour-weighted species scores.Abbreviations DCA Detrended Correspondence Analysis - OGU Operational Geographical Unit - OSP Ordination Space Partitioning - UPGMA Unweighted Pair-Group Method using Arithmetic Averages     

Folate-dependent enzymes in cultured Chinese hamster ovary cells: evidence for mutant forms of folylpolyglutamate synthetase

A Chinese hamster ovary auxotroph requiring glycine + adenosine + thymidine (CHO AUXB1) was shown by us previously to lack several folylpolyglutamate synthetase (FPGS) type activities. Two revertants of AUXB1 (one spontaneous and one Pt(S0₄)₂ induced) have been isolated and found to contain altered forms of this enzyme. The revertant enzymes are more sensitive to heat inactivation (37 °C, pH 7.4 or 9.0) than the parent CHO enzyme. Increased sensitivity of revertant FPGS is observed irrespective of whether one assays the specific catalysis of radioactive tetrahydropteroyldi- or tetraglutamate synthesis. ATP and MgCl₂ protect both revertant and parent CHO FPGS against rapid heat denaturation at pH 9.0, but not at pH 7.4. A genetically related auxotroph (CHO AUXB3) contains one-fifth the parent amount of FPGS. AUXB3 FPGS shows a normal sensitivity to 37 °C heat inactivation, but it has an altered substrate saturation and specificity pattern when assayed for tetrahydropteroyldi[U-¹⁴C]glutamate synthesis. Also, unlike the FPGS from parent CHO and a genetically unrelated mutant requiring only glycine (CHO AUXB2), the AUXB3 enzyme specifically lacks tetrahydropteroyltetra[U-¹⁴C]glutamate synthetase activity. These findings and polyethylene glycol fusion data with AUXB2 indicate that AUXB1 and AUXB3 each carry a mutation in the structural gene for a CHO FPGS that catalyzes tetrahydropteroyldi- as well as tetraglutamate formation. The altered form of FPGS in AUXB3 is responsible for its glycine + adenosine auxotrophy under standard culture conditions.     

Aerobic photolysis of alkylcobalamins: quantum yields and light-action spectra

Quantum yields (φ) for the aerobic photolysis of 5′-deoxyadenosylcobalamin (dAB₁₂), methylcobalamin (MeB₁₂), propylcobalamin (PrB₁₂), and ethylcobalamin (EtB₁₂) were determined as a function of the irradiation wavelength. φ Determinations were made for both the base-on and base-off forms of each compound (except base-off dAB₁₂) at incident wavelengths from 250 nm to 570 nm. As a rule, the φs were high (0.1–0.5) and they varied significantly with respect to the irradiation wavelength. In general, each alkylcobalamin at pH 7.0 displayed a quantum yield spectrum distinct from its base-off form at pH 1.0. Across most of the spectrum, the φs of the base-off form were appreciably smaller than the base-on φs of the same compound. An exception to this generality was MeB₁₂ for which the φs at pH 1.0 were about the same as, or slightly greater above 450 nm than those at pH 7.0. At pH 7.0 and in the visible region the trend of the φs was dAB₁₂ < MeB₁₂ < PrB₁₂ < EtB₁₂. Under neutral conditions each compound showed a broad quantum yield peak in the 450–470 nm region.From the quantum yield and absorption spectra, photolysis spectra were calculated for 5.0 × 10^?5m solutions of each compound. The light-action spectra accurately give the relative rates/μ Einstein that these solutions photolyze at each wavelength. Thus, for example, MeB₁₂ photolyzed faster at pH 7.0 versus pH 1.0 in 510 nm light, but it photolyzed slower at pH 7.0 versus pH 1.0 in 450 nm light. Solutions of each compound photolyzed faster in the ultraviolet region as opposed to the visible (e.g., 310 nm versus 510 nm).Our findings show that the previously reported photolysis rates estimated by others with tungsten lamps provide no valid information about the intrinsic photolability of various alkyl-cobalt bonds. This also applies to the relative white-light photolysis rates reported for the base-on versus the base-off form of MeB₁₂. All such relative rates are artifacts which represent only the extent of overlap between the true action spectrum and the light emission spectrum of an incandescent lamp.