The data suggest that patients with extraadrenal pheochromocytomas have the same risk of malignancy and the same overall survival as patients with adrenal pheochromocytomas. Lifelong follow-up of these patients is mandatory.

Angioedema is a potentially life-threatening adverse effect of angiotensin-converting enzyme inhibitors. Bradykinin and substance P, substrates of angiotensin-converting enzyme, increase vascular permeability and cause tissue edema in animals. Studies indicate that amino-terminal degradation of these peptides, by aminopeptidase P and dipeptidyl peptidase IV, may be impaired in individuals with angiotensin-converting enzyme inhibitor-associated angioedema. This case-control study tested the hypothesis that dipeptidyl peptidase IV activity and antigen are decreased in sera of patients with a history of angiotensin-converting enzyme inhibitor-associated angioedema. Fifty subjects with a history of angiotensin-converting enzyme inhibitor-associated angioedema and 176 angiotensin-converting enzyme inhibitor-exposed control subjects were ascertained. Sera were assayed for angiotensin-converting enzyme activity, aminopeptidase P activity, aminopeptidase N activity, dipeptidyl peptidase IV activity, and antigen and the ex vivo degradation half-lives of bradykinin, des-Arg(9)-bradykinin, and substance P in a subset. The prevalence of smoking was increased and of diabetes decreased in case versus control subjects. Overall, dipeptidyl peptidase IV activity (26.6+/-7.8 versus 29.6+/-7.3 nmol/mL per minute; P=0.026) and antigen (465.8+/-260.8 versus 563.1+/-208.6 ng/mL; P=0.017) were decreased in sera from individuals with angiotensin-converting enzyme inhibitor-associated angioedema compared with angiotensin-converting enzyme inhibitor-exposed control subjects without angioedema. Dipeptidyl peptidase IV activity (21.5+/-4.9 versus 29.8+/-6.7 nmol/mL per minute; P=0.001) and antigen (354.4+/-124.7 versus 559.8+/-163.2 ng/mL; P=0.003) were decreased in sera from cases collected during angiotensin-converting enzyme inhibition but not in the absence of angiotensin-converting enzyme inhibition. The degradation half-life of substance P correlated inversely with dipeptidyl peptidase IV antigen during angiotensin-converting enzyme inhibition. Environmental or genetic factors that reduce dipeptidyl peptidase IV activity may predispose individuals to angioedema.

Previous investigators have demonstrated variable responses to uvulopalatopharyngoplasty (UPP) in patients with obstructive sleep apnea. We hypothesized that this variability is due to either (1) differences in baseline pharyngeal collapsibility preoperatively or (2) differences in magnitude of the decrease in pharyngeal collapsibility resulting from surgery. To determine the relationship between changes in collapsibility and the response to UPP surgery, we measured the upper airway critical pressure (Pcrit) before and after UPP in 13 patients with obstructive sleep apnea. During non-REM sleep, maximal inspiratory airflow (VImax) was quantitated by varying the level of nasal pressure (PN), and Pcrit was determined by the level of PN below which VImax ceased. A positive response to UPP was defined by a greater than or equal to 50% fall in non-REM disordered breathing rate (DBR). In the entire group, UPP resulted in significant decreases in DBR from 71.1 +/- 22.4 to 44.7 +/- 38.4 episodes/h (p = 0.025) and in Pcrit from 0.2 +/- 2.4 to -3.1 +/- 5.4 cm H2O (p = 0.016). Moreover, the percent change in DBR was correlated significantly with the change in Pcrit (p = 0.001). Subgroup analysis of responders and nonresponders demonstrated that significant differences in Pcrit were confined to the responders. Specifically, responders demonstrated a significant fall in Pcrit from -0.8 +/- 3.0 to -7.3 +/- 4.9 cm H2O (p = 0.01), whereas no significant change in Pcrit was detected in the nonresponders (1.1 +/- 1.6 versus 0.6 +/- 2.0 cm H2O. No clinical, polysomnographic, or physiologic predictors of a favorable response were found preoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

SummaryAngiotensin converting inhibitors (ACEI) not only decrease angiotensin II (Ang II) but also potentiate the effects of bradykinin. Bradykinin is a potent stimulus to tissue type plasminogen activator (t-PA) secretion in animal models. In this study, we tested the hypothesis that bradykinin increases t-PA levels in humans.Bradykinin was infused in seventeen hypertensive patients randomized to treatment with the ACEIs captopril and quinapril or with placebo. Bradykinin caused a significant decrease in mean arterial pressure (MAP) (p = 0.014) and increase in pulse (p <0.001). ACEI significantly potentiated the hemodynamic effect of bradykinin (p <0.05). Although baseline t-PA antigen levels were similar in the ACEI-treated (6.85 ± 0.85 ng/ml) and placebo-treated (7.85 ± 0.68 ng/ml) subjects, bradykinin caused a significant (p <0.01) increase in t-PA antigen levels (to 19.3 ± 8.2) only in the ACEI-treated patients. This increase in t-PA was independent of activation of the sympathetic nervous system. Bradykinin had no effect on PAI-1 antigen levels.These in vivo data suggest that infusion of bradykinin results in an increase in circulating t-PA levels without an effect on PAI-1.

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