Maintenance digoxin after an episode of heart failure: placebo-controlled trial in outpatients.

The need for maintenance digoxin treatment was assessed in a double-blind, variable-dose, crossover comparison with placebo. Forty-six outpatients who had been prescribed the drug for heart failure were studied; 33 were in sinus rhythm and the remainder in atrial fibrillation. Mean serum digoxin concentrations in those with sinus rhythm averaged 1-33 nmol/l, but a lower concentration, averaging 0-97 nmol/l, was accepted in those with atrial fibrillation as six of them developed bradycardia. Sixteen of the 46 patients deteriorated on placebo, and eight completely recovered when digoxin was reintroduced; in the remainder additional diuretics were required temporarily. Spirometric values deteriorated on changing to placebo whether or not the patient showed clinical evidence of recurrence of heart failure. In a separate study of nine patients who showed no clinical evidence of deterioration on placebo, reintroduction of digoxin caused a shortening of left ventricular ejection time, which persisted for at least a month. This suggests that the inotropic response to digoxin is sustained during maintenance treatment.     

The breeding biology of Grallaria and Grallaricula antpittas

ABSTRACT Grallaria and Grallaricula antpittas are poorly known ground antbirds (Formicariidae), which reach their center of diversity in the tropical Andes region. Here we review published literature on the reproductive ecology of these two genera, summarizing and synthesizing the information. Nests have been described for 13 of the 31 species of Grallaria and four of the eight species of Grallaricula. For both genera, nests are open cups placed either against a strong support (e.g., tree trunks; Grallaria) or with multiple small supports (e.g., vine tangles; both genera). Nest lining is generally sparse, with nest cup composition ranging from humid material (e.g., moss) to primarily sticks and leaf material, depending on the species. Grallaria typically lay two bluish‐green to turquoise eggs, sometimes with spotting, whereas Grallaricula lay 1–2 eggs with heavy markings and pale brown or buffy (rarely light green) background coloration. For the few species where information is available, both male and female parents are believed to participate in building, incubation, and nestling provisioning, with high incubation attentiveness (often >90%, especially later in incubation), and incubation periods of 17–21 d (Grallaria) and 15–20 d (Grallaricula). Grallaria nestlings are frequently fed earthworms (Oligochaeta) in addition to a variety of arthropods. Nestlings have pale skin (Grallaria) or dark skin (both genera), with pale or dark down (Grallaria) or red‐brown down (Grallaricula). Nestlings in both genera usually have brilliant orange mouth linings and cloacas, and usually fledge 15–19 d post hatching. Rapid probing, where adults rapidly thrust their bills into the nest and lining, is commonly observed across species during incubation and nestling periods, but its function remains unknown. Overall, our knowledge of the breeding biology of antpittas has improved significantly in recent years. However, much remains to be learned for most species.     

Localization of 3′,5′-cyclic adenosine monophosphate phosphodiesterase (cAMP-PDEase) activity in isolated bovine thyroid plasma membranes

Summary Isolated bovine thyroid plasma membrane preparations were obtained by isopycnic density gradient centrifugution. Cyclic AMP-PDEase (EC 3.1.4.c) activity has been demonstrated by electron microscopic histochemistry on the unit membrane of isolated bovine thyroid cells. 3-isobutyl-1-methyl-xanthine (IBMX) produced partial inhibiton, while omission of the substrate revealed no reaction product deposition. These observations correlated well with biochemical studies that showed 0.4% of the total cAMP-PDEase activity to be present in the plasma membrane preparations. Kinetic analysis of cAMP hydrolysis yielded two apparent Michaelis constants for the homogenate and the plasma membrane-rich fraction. Dose-response curves for IBMX inhibition showed cAMP-PDEase of the homogenate to be more sensitive to inhibition than that of the plasma membrane-bound enzyme. Furthermore, wash experiments indicate that the plasma membrane-associated enzyme is tightly bound. This investigation strengthens our previous study and suggests that bovine thyroid cell plasma membranes contain a cAMP-PDEase that may be involved in interactions between the cell and the external environment in a manner yet to be determined.     

Pandemic Serotypes of Vibrio cholerae Isolated from Ships’ Ballast Tanks and Coastal Waters: Assessment of Antibiotic Resistance and Virulence Genes (tcpA and ctxA)

There is concern that ships’ ballasting operations may disseminate Vibrio cholerae to ports throughout the world. Given evidence that the bacterium is indeed transported by ships, we isolated pandemic serotypes O1 and O139 from ballast tanks and characterized them with respect to antibiotic resistance and virulence genes ctxA and tcpA. We carried out concurrent studies with V. cholerae isolated from coastal waters. Of 284 isolates, 30 were serotype O1 and 59 were serotype O139. These serotypes were overrepresented in ballast tanks relative to the coastal waters sampled. All locations, whether coastal waters or ballast tanks, yielded samples from which serotype O1, O139, or both were isolated. There were three groups among the 62 isolates for which antibiotic characterization was conclusive: those exhibiting β-lactamase activity and resistance to at least one of the 12 antibiotics tested; those negative for β-lactamase but having antibiotic resistance; those negative for β-lactamase and registering no antibiotic resistance. When present, antibiotic resistance in nearly all cases was to ampicillin; resistance to multiple antibiotics was uncommon. PCR assays revealed that none of the isolates contained the ctxA gene and only two isolates, one O139 and one O1, contained the tcpA gene; both isolates originated from ballast water. These results support the bacteriological regulations proposed by the International Maritime Association for discharged ballast water.