Correlation of changes in cardiac calcium channels with hemodynamics in Syrian hamster cardiomyopathy and heart failure

We compared hemodynamics with [3H]nitrendipine (calcium channel) binding to cardiac membranes from Bio 14.6 cardiomyopathic Syrian hamsters at 4 and 10 months with their F1B controls. A 50% increase in the number (Bmax) of nitrendipine binding sites (calcium channels) was seen only in the 4 month old myopathic vs controls (Bmax = 468 +/- 11 vs 309 +/- 10 fmol/mg prot with no change in affinity (KD) (KD = .65 +/- .12 vs .75 +/- .14 nM), while no differences in Bmax or KD were seen at 10 months (Bmax = 375 +/- 9 vs 362 +/- 7 fmol/mg prot/KD = .82 +/- .18 vs .89 +/- .17 nM) myopathic vs control respectively. Hemodynamic studies revealed no significant differences in cardiac output, cardiac index, stroke volume, heart rate, mean arterial pressure, peripheral resistance, body weight, heart weight at 4 months, but a significant decrease in peripheral resistance (1120 +/- 360 vs 2080 +/- 240) increase in body weight (118 +/- 2 vs 94 +/- 2 grams) and heart weight (97 +/- 5 vs 78 +/- 2 gms/100 gms body weight) in 10 month myopathic vs control animals. We conclude that the onset of cardiomyopathy at 4 months is associated with a selective increase in calcium channel binding sites and heart failure at 10 months is associated with a relative decrease in these sites.     

Effect of glucocorticoids on the response of airway smooth muscle to catecholamine and resorcinol beta-agonists

The influence of hydrocortisone (11 beta, 17 alpha, 21-trihydroxy-pregn-4-ene-3,20-dione) or of methylprednisolone (6 alpha-methyl-11 beta, 17 alpha-21-trihydroxy-1,4-pregnadiene-3,20-dione) on the response of airway smooth muscle to a variety of beta-adrenergic bronchodilators was evaluated using incubated guinea pig tracheal rings, preconstricted with histamine. The adrenergic agonists chosen for this study included the nonselective beta 1- and beta 2-catecholamine, isoproterenol, the selective beta 2-catecholamine, rimiterol, and the selective beta 2-resorcinols, fenoterol and terbutaline. When the incubated rings were pretreated with 10-50 micrograms/mL of the steroids, there was a significant enhancement in smooth muscle sensitivity and reactivity to rimiterol and isoproterenol. Tracheal response to fenoterol or terbutaline, on the other hand, was not altered by the glucocorticoids. When used alone, neither steroid exerted an inotropic influence on the tracheal smooth muscle. The results of our study indicate that glucocorticoid enhancement of adrenergic bronchodilators is selective for catecholamines, and not for resorcinols.     

Ornithogenic soils of the Cape Bird adelie penguin rookeries,Antarctica

Summary Ammonia evolution and urease, phosphatase and protease activities were measured after field incubations of soil from 5 sites, differently influenced by penguin guano, from Cape Bird, Antarctica. Rates of NH₃ production were low considering the large amounts of free NH₃ in these soils. Enzyme activities were higher than expected and, under optimum conditions of temperature, moisture and substrate availability, were sufficient to degrade rapidly the accumulated organic matter in these soils. Laboratory incubations confirmed these high levels of activity; they also showed high dehydrogenase, but not sulphatase, activity. The surface horizon from the site that received continuous additions of fresh penguin excreta had considerably more enzyme activity than the other samples. The optimum activity of phosphatase in this sample was at pH 9.5-10. These enzyme activities are compared with those of New Zealand topsoils, and considered in relation to activities likely to occur under field conditions. Recommendations are made for further biochemical studies at Cape Bird.     

Soil restoration under pasture after lignite mining: Management effects on soil biochemical properties and their relationships with herbage yields

The recovery of soil biochemical properties under grazed, grass-clover pasture, after simulated lignite mining, was studied over a 5-year period in a mesic Typic Dystrochrept soil at Waimumu, Southland, New Zealand. The restoration procedures involved four replacement treatments, after A, B, and C horizon materials had been separately removed, from all except the control, and stockpiled for 2–3 weeks. In each replacement treatment, the effects of ripping to 1.8 m depth, mole drainage, and the use of fertilizer nitrogen were also investigated.Replacement treatment markedly influenced the recovery of herbage production and soil organic C and total N contents, N mineralization, microbial biomass (as indicated by mineral-N flush) and invertase and sulphatase activities. The effectiveness of replacement treatments decreased in the order: 1. control (no stripping or replacement). 2 A, B, and C horizon materials replaced in the same order. 3. A, B, and C horizon materials each mixed with an equal amount of siltstone overburden and replaced in order, 4. A and B horizon materials mixed before replacing over C horizon material.Ripping increased herbage production, net N mineralization, and to some extent microbial biomass. Drainage had little, if any, effect.Fertilizer N also stimulated herbage production, but depressed clover growth. Over 2.5 years, it had little detectable effect on the soil properties.Increases in soil invertase and, to a lesser extent, sulphatase activity during the trial were closely related to changes in herbage production. Microbial biomass increased more rapidly than did soil organic C in the early stages of the trial.Rates of net N mineralization strongly suggest that N availability would have limited pasture growth, especially in the treatments with mixed soil materials.     

Silicon concentrations and stoichiometry in two agricultural watersheds: implications for management and downstream water quality

Biogeochemistry - Agriculture alters the biogeochemical cycling of nutrients such as nitrogen (N), phosphorus (P), and silicon (Si) which contributes to the stoichiometric imbalance among these...     

Facilitation of isoproterenol induced airway smooth muscle relaxation by nifedipine

The facilitating effect of nifedipine on isoproterenol induced airway smooth muscle relaxation was studied in guinea pig tracheas. For isometric force measurement, 4 mm tracheal cylinders were suspended in incubation chambers in oxygenated physiologic medium. After 90 minutes of equilibration under 2 grams resting tension, at a temperature of 37 degrees C and pH of 7.4, concentration response curves for isoproterenol were performed with and without the addition of a 1 X 10(-5)M nifedipine dose. The experiments were then repeated using tissues precontracted with histamine. Our data show that in the nifedipine pretreated tissues, the EC50 of isoproterenol is shifted to the left (p less than 0.05) probably due to further reduction in cytosolic calcium by nifedipine. Our findings suggest that nifedipine might have a role in the treatment of asthma and obstructive airway disease.     

Studies of mediator involvement in cooling-induced alterations of guinea pig tracheal smooth muscle contractility

Heat loss from airway smooth muscle is a potent stimulus which causes substantial, but poorly understood, alterations in muscle tension. This study considered the involvement of endogenous mediators in cooling-induced tension changes in incubated guinea pig trachea. Smooth muscle tension was monitored in tracheal cylinders which were carefully cooled from 37 to 30 degrees C in the presence or absence of various inotropic mediators. In our study, cooling alone, at a rate of 1 degree C/min, was associated with an average loss of smooth muscle tension of 88.2 mg. Cooling tracheal tissue that had been previously exposed to 3 X 10(-6) M histamine, however, caused an additional increase in tracheal tension of 133 mg, over and above that caused by histamine alone. In the presence of 10(-5) M prostaglandin F2 alpha, or 10(-5) M thromboxane B2, cooling was associated with respective losses of smooth muscle tension of 211.4 and 211.2 mg, as compared to the tension associated with these mediators when they were used alone under control conditions. When the speed of tracheal cooling was increased to 40 degrees C/min, there was a slight increase in tension for 20 sec followed by a pronounced and sustained relaxation. The mechanisms involved in the response of airway smooth muscle to cooling are complex. The results of our study, however, suggest that mediators may play a role in the cooling-induced alterations of airway smooth muscle tension.     

Mobility and survival of Salmonella Typhimurium and human adenovirus from spiked sewage sludge applied to soil columns

Aims:  This study investigated the survival and transport of sewage sludge-borne pathogenic organisms in soils.
Methods and Results:  Undisturbed soil cores were treated with Salmonella enterica ssp. enterica serovar Typhimurium- lux (STM- lux ) and human adenovirus (HAdV)-spiked sewage sludge. Following an artificial rainfall event, these pathogens were analysed in the leachate and soil sampled from different depths (0–5 cm, 5–10 cm and 10–20 cm) after 24 h, 1 and 2 months. Significantly more STM- lux and HAdV leached through the soil cores when sewage sludge was present. Significantly more STM- lux were found at all soil depths, at all time periods in the sewage sludge treatments, compared to the controls. The rate of decline of STM- lux in the controls was more rapid than in the sewage sludge treatments. Survival and transport of HAdV were minimal.
Conclusions:  The presence of sewage sludge can significantly influence the transport and survival of bacterial pathogens in soils, probably because of the presence of organic matter. Environmental contamination by virus is unlikely because of strong soil adsorption.
Significance and Impact of the Study:  This study suggests that groundwater contamination from vertical movement of pathogens is a potential risk and that it highlights the importance of the treatment requirements for biosolids prior to their application to land.