The effect of acute and chronic glucocorticoid excess on leucine kinetics and protein turnover in vivo

The present studies were undertaken to assess the effects of excess cortisol on amino acid exchange in the conscious dog. Three groups of 18-hr fasted dogs with catheters chronically implanted in the femoral artery were studied: Group I (n = 6) received saline; Groups II and III (n = 5, each) received ACTH intravenously (1 U/min) for 7 hr; in addition, Group III received ACTH, 500 U/day intramuscularly for 4 days. Leucine rates of appearance (Ra) and clearance were measured using a constant infusion of L-4,5-[3H]leucine. ACTH treatment resulted in a 9-fold increase in plasma cortisol in Groups II and III (from 2 +/- 1 to 18 +/- 1 and 17 +/- 2 micrograms/dl, in II and III, respectively P less than 0.001), with no effect on either plasma insulin or glucagon. Plasma leucine (mmole/liter) increased from 118 +/- 6 (I) to 153 +/- 6 (II, P less than 0.005) to 275 +/- 35 (III, P less than 0.001). Leucine Ra (micromoles/kilogram/minute) did not change in II, but rose by 39% (P less than 0.005) in III. Clearance (milliliters/kilogram/minute) dropped from 25 +/- 2 (I) to 18 +/- 2 (II, P less than 0.005), to 15 +/- 2 (III, P less than 0.001). It is concluded that acute elevations of cortisol increased plasma leucine only by inhibiting its rate of disposal, whereas chronic elevations had a dual effect; they inhibited leucine disposal and increased its entry into the plasma compartment, suggesting an inhibition of protein synthesis and stimulation of protein breakdown.     

Crusted (Norwegian) scabies. Occurrence in a child undergoing a bone marrow transplant

A case of crusted (Norwegian) scabies is reported in a child who was a recipient of a bone marrow transplant. The infestation is presumed to have predated the bone marrow transplant and continued asymptomatically during chemotherapy and total body x-irradiation in preparation for transplant. The child was asymptomatic until 23 days after transplantation, when bone marrow engraftment was attained. The altered host-parasite relationship is emphasized by the observation that the onset of symptomatic pruritus coincided with successful engraftment.     

The relationship between gastroesophageal reflux and asthma: an update

Asthma and gastroesophageal reflux disease (GERD) are both common conditions and, hence, they often coexist. However, asthmatics have been found to have a much greater prevalence of GERD symptoms than the general population. There remains debate regarding the underlying physiologic mechanism(s) of this relationship and whether treatment of GERD actually translates into improved asthma outcomes. Based on smaller trials with somewhat conflicting results regarding improved asthma control with treatment of GERD, current guidelines recommend a trial of GERD treatment for symptomatic asthmatics even without symptoms of GERD. However, recently a large multicenter trial demonstrated that the treatment of asymptomatic GERD with proton-pump inhibitors did not improve asthma control in terms of pulmonary function, rate of asthma exacerbations, asthma-related quality of life, or asthma symptom frequency. These data suggest empiric treatment of asymptomatic GERD in asthmatics is not a useful practice. This review article provides an overview of the epidemiology and pathophysiologic relationships between asthma and GERD as well as a summary of current data regarding links between treatment of GERD with asthma outcomes.