Almitrine and doxapram decrease fatigue and increase subsequent recovery in isolated rat diaphragm

McGuire, Michelle, Michael F. Carey, and John J. O'Connor.Almitrine and doxapram decrease fatigue and increase subsequent recovery in isolated rat diaphragm. J. Appl.Physiol. 83(1): 52-58, 1997.The effects ofalmitrine bimesylate and doxapram HCl on isometric force produced by invitro rat diaphragm were studied during direct muscle activation at37°C. Doxapram and almitrine ameliorate respiratory failureclinically by indirectly increasing phrenic nerve activity. This studywas carried out to investigate possible direct actions of these agentson the diaphragm before and after fatigue of the fibers. Two age groupsof animals were chosen [6-14 wk (group1) and 50-55 wk (group2)] because it is known that increasing agedecreases a muscle fiber's resistance to fatigue. Muscle strips wereisolated from both group 1 and group 2 and directly stimulated (2-mspulse duration, 5-15 V) to produce twitch tensions of 1.3 and 2.1 N/cm², respectively. At lowconcentrations, doxapram (20 µg/ml) and almitrine (12 µg/ml)had no effect on twitch contraction or 100-Hz tetanic tension. However,40 µg/ml doxapram and 30 µg/ml almitrine increased twitch tensionby 9.0 ± 1.4 and 11.6 ± 1.9%, respectively, in animals ofgroup 2 (n = 5). A fatigue protocol consistingof low-frequency stimulation (30-Hz trains, 250-ms duration every 2 sfor 5 min) caused a reduction of twitch tension in animals ofgroup 1 (48 ± 4% ofcontrol) and group 2 (28 ± 4% ofcontrol). At 90 min postfatigue, the twitch tension recovered to 72 ± 3 and 42 ± 2% of control values ingroup 1 and group2, respectively. In the presence of doxapram (20 µg/ml), there was a significant increase in the recovery of twitchtension at 90 min in group 1 andgroup 2 (84.5 ± 3.2 and 80.1 ± 2.8%, respectively) compared with controls at 90 min postfatigue. Inthe presence of almitrine (12 µg/ml), there was a full recovery fromfatigue in group 1 animals (100% ofcontrol) and a recovery to 95.6 ± 2.1% of control ingroup 2 animals at 90 min. Theseresults demonstrate a significant improvement in the rapidity andmagnitude of recovery from fatigue in the rat diaphragm muscle in thepresence of both doxapram and, especially, almitrine. These effects maybe due to changes in intracellular calcium, ADP/ATP ratios, or oxygenfree radical scavenging.

     

Tyrosine hydroxylase in the cerebral ganglia of the American cockroach (Periplaneta americana L.): an immunohistochemical study

We have investigated the distribution of tyrosine-hydroxylase-like immunoreactivity in the cerebral ganglia of the American cockroach, Periplaneta americana. Groups of tyrosine-hydroxylase-immunoreactive cell bodies occur in various parts of the three regions of the cerebral ganglia. In the protocerebrum, single large neurons or small groups of neurons are located in the lateral neuropil, adjacent to the calyces, and in the dorsal portion of the pars intercerebralis. Small scattered cell bodies are found in the outer layers of the optic lobe, and clusters of larger cell bodies can be found in the deutocerebrum, medial and lateral to the antennal glomeruli. Thick bundles of tyrosine-hydroxylase-positive nerve fibers traverse the neuropil in the proto- and deutocerebrum and innervate the glomerular and the nonglomerular neuropil with fine varicose terminals. Dense terminal patterns are present in the medulla and lobula of the optic lobe, the pars intercerebralis, the medial tritocerebrum, and the area surrounding the antennal glomeruli, the central body and the mushroom bodies. The pattern of tyrosine-hydroxylase-like immunoreactivity is similar to that previously described for catecholaminergic neurons, but it is distinctly different from the distribution of histaminergic and serotonergic neurons.     

Seasonal and area-related variations in the diet of otters Lutra lutra on Mull

The diet of otters Lurra lutrn living in a sea loch on the Isle of Mull was described by means of spraint analysis. Seasonal and spatial differences in the spraint composition were explored in the context of fluctuations in prey availability, as revealed by trapping. Butterfish Pholis gunnellus and the cottids Myoxocephalus scorpius and Taurulus bubalis were the most commonly occurring prey in spraints. In the winter, the proportion of rocklings ( Ciliata spp. and Gaidropsarus spp.) and non-rockling gadoids (Gadidae) in the diet increased. Their relatively large size makes these latter species an important constituent of the winter diet. Seasonal and spatial variation in fish consumption largely reflected fluctuations in availability. The mean size of principal prey fishes in spraints was similar to that observed in the traps. These observations suggest that otters were not strongly selective with regard to fish species and size. Shore crabs, in contrast, were not taken in proportion to availability. The findings are discussed in the light of other studies of the diet of coastal otters. It is suggested that the lack of selectivity demonstrated in this study, compared with previous studies, may be explained by area-related variations in prey availability.     

The complete amino acid sequence of the major alpha subunit of the lectin from the seeds of Dioclea grandiflora (Mart)

The complete amino acid sequence of the major alpha subunit of the lectin from seeds of Dioclea grandiflora was determined. The sequence was deduced from analysis of peptides derived from the native alpha subunit by digestion with trypsin, chymotrypsin, the Staphylococcus aureus V8 protease, and pepsin; and from larger peptides produced by digestion of the citraconylated protein with trypsin. The alpha subunit consists of a single polypeptide chain of 237 amino acids which differs from the sequence of concanavalin in 53 positions. Significant levels of heterogeneity were observed in five positions in the sequence.     

Reciprocal translocation and the Philadelphia chromosome

Summary We examined metaphases from three patients with chronic myeloid leukaemia and a typical Philadelphia chromosome with one chromosome 9 as the recipient to determine whether the 9q+ 22q- translocation is reciprocal. Good quality G-banded photographs of the chromosomes concerned were subjected to light absorption density analysis. This provided enlarged tracings corresponding to the relevant chromosome regions and so facilitated accurate measurement. This technique has unambiguously shown that the typical Philadelphia chromosome results from a reciprocal translocation and that probably no material is gained or lost in the exchange. Furthermore, in a total of six patients for whom sequential G and C banding was performed, the chromosome 9 with the largest block of centromeric heterochromatin received the translocated material. We offer tentative explanations for this curious observation.     

Coastal dune stability: The effect of meteorological conditions and vegetation

Quantitative investigations and research conducted along the north coast of New South Wales, Australia are evaluated with respect to coastal processes, coastal alignment, meteorological data, dune dimensions, dune vegetative cover, development on the dunal area and dune management.The data available covered an assessment of the extent of dune instabilities, an assessment of long term coastline movements, a study of the effect of a cyclone and storm surge, and an assessment and evaluation of a phase of extreme coastline erosion. Specific situations are described and evaluated within the above context. The evaluations are used to determine the extent of coastal dune areas required to be designated as buffer zone in land use planning. The extent of the zone required is dependent upon expected magnitude of wave erosion. Magnitude of wave erosion was found to be proportional to the interaction of coastal processes during periods of extreme erosive factors and the beach dune characteristics for the particular section of coastline. It was found that man's influence on this natural interaction can be a dominating factor in determining beach dune characteristics and therefore the magnitude of wave erosion. — management of the beach dunal area to maintain an acceptable dynamic equilibrium of the beach dune line by a vegetated sand dune of specific dimensions is possible despite weather conditions, if a designated buffer zone is maintained.Presented at the Seventh International Biometeorological Congress, 17–23 August 1975, College Park, Maryland, USA.     

Clonal variation in adrenocorticotropin-induced desensitization of adenylate cyclase in Y1 adrenocortical tumor cells. Association with a 68,000-dalton protein

Adrenocorticotropin(ACTH)-induced desensitization of adenylate cyclase was examined in subclones derived from the ACTH-responsive, Y1 mouse adrenocortical tumor cell line. This report describes clonal variation in ACTH-induced desensitization of adenylate cyclase and an associated variation in the level of a 68,000-dalton protein, p68. A subclone of Y1 cells with a low level of p68 (0.8% of total protein) exhibited a faster rate of desensitization and a slower rate of recovery from desensitization when compared with a clone containing a high level of p68 (10% of total protein). In three clones with low levels of p68, ACTH desensitized adenylate cyclase with ED50 values from 0.3 to 0.5 nM. In several clones with high levels of p68, the adenylate cyclase system was more resistant to ACTH-induced desensitization; the ED50 values for ACTH in these clones ranged from 2 to 12 nM. Among 11 ACTH-responsive subclones, the level of p68 correlated significantly (p less than 0.001, r = 0.87) with resistance to the desensitization induced by 1 nM ACTH. These results suggest that p68 may function in the maintenance of an ACTH-responsive adenylate cyclase system, or that the level of p68 and responsiveness to ACTH are coordinately regulated.     

Variations in surface protein composition associated with virulence properties in opacity types of Neisseria gonorrhoeae.

The biological properties of a series of opacity variants of Neisseria gonorrhoeae P9 have been examined. A novel protein, designated protein IId* (mol. wt 28 850), was identified within the set of heat-modifiable surface proteins previously reported. All variants producing extra outer membrane proteins were less sensitive to the bactericidal action of serum than the prototype transparent strain, with protein IIa* (mol. wt 28 500) being associated with increased resistance. The production of a different protein, protein II* (mol. wt 29 000), was correlated with resistance to low molecular weight antimicrobial agents (penicillin, fusidic acid, Cu2+, Zn2+). Increased adhesion to human buccal epithelial cells was demonstrated in all variants that produced extra surface proteins. These variants did not show increased binding to hexyl- and phenyl-substituted Sepharose gels suggesting that hydrophobic interaction was not responsible for their cohesive properties. The prototype strain lacking additional proteins demonstrated the greatest binding to erythrocytes, indicating that adhesion to buccal cells and red blood cells is mediated by different mechanisms. One variant producing protein IIa* showed increased association with leukocytes, whereas another producing protein IIb* showed decreased association with leukocytes. These results show that the heat-modifiable surface proteins are important virulence attributes of the gonococcus: this must be considered in the selection of strains for vaccine trials.     

An inducible hydrolase from Mortierella isabellina (basidiomycetes). The deacylation of (+)-usnic acid

An inducible enzyme catalysing the hydrolysis of (+)-usnic acid to (+)-2-desacetylusnic acid and acetic acid has been purified 150-fold from the mycelium of Mortierella isabellina grown in the presence of (+)-usnic acid. Purification was achieved by treatment with protamine sulfate, (NH₄)₂SO₄ fractionation, negative adsorption on alumina Cγ gel and hydroxylapatite followed by chromatography on DEAE-cellulose and Sephadex G-200. The elution pattern from a Sephadex G-200 column indicated a MW of ca 7.6 × 10⁴ for the enzyme. The apparent K_m value for (+)-usnic acid at the pH optimum (pH 7) was 4.0 × 10^?5 M. The enzyme was specific for (+)-usnic acid and inactive towards (?)-usnic acid, (+)-isousnic acid or certain phloracetophenone derivatives. Its activity was enhanced in the presence of divalent metal ions such as Co²⁺, Ni²⁺, Mn²⁺, Mg²⁺ and Zn²⁺.     

Determination of the strength of the cell walls of vegetative cells ofBacillus megaterium andBacillus stearothermophilus

The tensile strength of the cell walls ofBacillus megaterium andBacillus stearothermophilus was found to be about 2.4×10⁷ N/m². The internal pressure and water activity of the cells were 14 atm, 0.99 a_w forB. megaterium and 28 atm, 0.98 a_w forB. stearothermophilus. The greater strength ofB. stearothermophilus cells, considered as pressure vessels, restricts absorption of water by the protoplasm so that the water content on a dry weight basis is 3.4 g/g forB. megaterium cells in water but only 1.8 g/g forB. stearothermophilus.