Effect of inhaled prostaglandin D2 in normal and atopic subjects, and of pretreatment with leukotriene D4

BACKGROUND

Prostaglandin (PG) D2 is a potent bronchoconstrictor mediator and is found, together with leukotriene (LT) D4, in bronchoalveolar lavage fluid during the early response to allergen challenge in asthmatic subjects. The potency of PGD2 has not been established in normal and atopic non-asthmatic subjects, nor has the contribution of cholinergic mechanisms to PGD2 induced bronchoconstriction in normal subjects. Mediators released simultaneously may interact, so the effect of pre-inhalation of LTD4 on PGD2 responsiveness was investigated.

METHODS

Six normal and six atopic non-asthmatic subjects performed histamine and PGD2 challenges on separate occasions. Eight normal subjects performed PGD2 challenges immediately before and 45 minutes after inhalation of 200 micrograms oxitropium bromide or placebo. Bronchial responsiveness to PGD2 was established in six normal subjects immediately after pretreatment with saline or non-bronchoconstricting doses of methacholine or LTD4 (challenge 1), and again at six hours (challenge 2). All studies were performed in a double blind, randomised, crossover fashion.

RESULTS

PGD2 was 25-fold and 18-fold more potent as a bronchoconstrictor than histamine in atopic non-asthmatic and normal subjects, respectively. Responsiveness (PC35sGaw) to histamine and PGD2 correlated significantly (r = 0.917, n = 12, p < 0.001). Oxitropium bromide in a dose of 200 micrograms inhibited PGD2 induced bronchoconstriction by 37.5%, although in two of these subjects no inhibition was seen. Pre-inhalation of LTD4 and methacholine shifted the dose-response curve of PGD2 to the left by 4.6-fold and 2.4-fold, respectively.

CONCLUSIONS

PGD2 is a potent bronchoconstrictor in normal subjects, which is partly mediated by cholinergic mechanisms in some subjects. No significant interaction was found between LTD4 and PGD2 in six normal subjects.

The effect of inhaled leukotriene B4 in normal and in asthmatic subjects

Leukotriene (LT) B4 is a potent leukocyte chemotaxin that increases bronchial responsiveness in animal models. In a double-blind, placebo-controlled crossover study we examined the effects of LTB4 on lung function, bronchial responsiveness, and blood leukocyte counts in six normal subjects and in six subjects with mild asthma who inhaled mean +/- SEM doses of 17.6 +/- 3.4 and 18.2 +/- 1.9 microg LTB4, respectively, or placebo. There were no significant changes in specific airway conductance or bronchial responsiveness in either normal subjects or asthmatics for as long as 24 h after inhalation. In the normal subjects, LTB4 rapidly reduced blood neutrophil counts to 19.8 +/- 6.3% of baseline at 5 min (p = 0.0003 compared with placebo), followed by a neutrophilia of 307 +/- 40% of baseline at 30 min (p = 0.007). Similar changes occurred in asthmatics, with a neutropenia at 5 min (69.6 +/- 5.8%; p = 0.003) and a neutrophilia at 30 min (183 +/- 17.2%; p = 0.037). The neutrophilia was not sustained in either subject group, with values being no different from that of placebo by 6 h. The asthmatics had significantly less neutropenia (p = 0.005) and less neutrophilia (p = 0.018) than did the normal subjects. Placebo inhalation had no effect on any parameter in either group. The smaller neutrophil responses in asthmatics may reflect desensitization of blood neutrophils in vivo because of chronic exposure to endogenous LTB4.

Psychosocial effects of cancer economics on patients and their families

Cancer frequently follows an unpredictable course, with patients experiencing numerous disruptions in their lives. Concomitantly, the enormous financial burdens that accompany the onset and subsequent treatment of cancer become even more overwhelming. Regardless of socioeconomic status, almost all families confronted with cancer and its treatment will have financial problems. Poor people are more likely to be diagnosed with cancer when the disease is advanced and treatment options are significantly more limited. Limited access to medical care carries the additional risk of denied access to community resources, which often are made through referrals from the health care system. For the middle-class family with insurance, as medication costs increase (whether they are covered or not), financial deprivations accumulate as out-of-pocket expenditures, because of required insurance deductibles and copayments and wages lost because of aspects of the treatment. Therefore, even those who are insured can be financially devastated by substantial gaps in coverage. A diagnosis of cancer compounds the struggle for survival and introduces new financial, physical, and psychologic demands. As a nation, we must ensure that cancer prevention, detection, treatment, and rehabilitation services are accessible and available to all who need them, regardless of their ability to pay.

Delayed seizures following sedation with propofol

Seizures occurred in two adolescents approximately six hours after sedation with propofol for bone marrow biopsy. Case #1 was a patient with chronic renal failure, hypertension, and anaemia. Case #2 had just been diagnosed with acute lymphocytic leukaemia. Neither child had experienced seizures before, and both recovered without neurological sequelae. Although other factors may have caused the seizures, the episodes have raised concerns about the safety of propofol for patients travelling home after out-patient surgery. Further study is required to explain the cause of this complication or, at least, to identify risk factors.