Inhalation of single vs multiple metered-dose bronchodilator actuations from reservoir devices. An in vitro study

Differences in inhalation technique with reservoir or spacer devices may affect metered-dose inhaler (MDI) dose availability to a patient. PURPOSE: This study examined the effect of single vs multiple actuations of an MDI into reservoir devices on dose delivery of albuterol, with three clinically available reservoir brands. METHODS: An in vitro lung model simulated inspiration from the MDI reservoir system. Albuterol (Proventil; Schering) was delivered by MDI, with the Monaghan Aerochamber, the Diemolding Healthcare Division (DHD) aerosol cloud enhancer (ACE), and the Schering InspirEase, using standardized volumes and inspiratory flows of 30 L min(-1). The MDI was actuated into each brand of reservoir 1, 2, or 3 times in rapid succession, followed by a single inhalation. Aerosol dose at the reservoir mouthpiece was captured on a cotton filter, dissolved in ethanol, and measured with a spectrophotometer at 278 nm. RESULTS: For all three brands of reservoir, less accumulated dose of drug is delivered with multiple actuations than with multiple single actuations each followed by inhalation. The total dose in milligrams increased significantly with two multiple actuations compared with one actuation in the Aerochamber and ACE (p<0.01), but not in the InspirEase (p>0.05). The Aerochamber, ACE, and InspirEase delivered a mean total dose (SD) of 0.0264 mg (0.012), 0.0271 mg (0.007), and 0.0136 mg (0.006), respectively, with one actuation compared to 0.0485 mg (0.011), 0.0453 mg (0.013), and 0.0218 mg (0.009) with two multiple actuations. The increase in total dose with three multiple actuations was not significant compared to two actuations for any of the brands tested (p>0.05). Although total dose increased with multiple actuations, a decline in efficiency was seen with two and three multiple actuations, compared to single actuation. The dose delivered per actuation decreased for the Aerochamber, ACE, and InspirEase from 0.0264 mg (0.012), 0.0271 mg (0.007), and 0.0136 mg (0.006) with one actuation, to 0.0243 mg (0.006), 0.0226 mg (0.006), and 0.0109 mg (0.005), respectively, with two multiple actuations, for losses of 8.0%, 16.6%, and 19.9% in dose per actuation for each brand. A further decline in delivery per actuation to 0.0164 mg (0.001), 0.0184 mg (0.004), and 0.0097 mg (0.005) for the 3 brands, respectively, was found with 3 multiple actuations before inhalation. This was a loss of 37.9%, 32.1%, and 28.7% of the dose per single actuation in each brand. There was no significant difference between the Aerochamber and the ACE in dose availability with 1, 2, or 3 actuations, but both of these brands provided significantly more drug than the InspirEase. CONCLUSION: Maximal aerosol bronchodilator from an MDI reservoir was given by single actuations each followed by a breath. Two rapid actuations followed by a breath will give a significant accumulation of dose with some loss when compared to two single actuations each followed by inhalation. Three multiple actuations led to a loss of approximately one third of the drug dose obtainable with three single actuations each followed by inhalation, for all three brands.     

Bombesin receptor subtype mediation of gastroenteropancreatic hormone secretion in rats

Bombesin is a potent releaser of many gut and pancreatic hormones including gastrin, glucose-dependent insulinotropic polypeptide (GIP), pancreatic polypeptide (PP), cholecystokinin (CCK), enteroglucagon, and insulin. Three mammalian bombesin-like peptides, gastrin-releasing peptide (GRP), neuromedin C (NMC or GRP-10), and neuromedin B (NMB), and two bombesin receptor subtypes, GRP preferring and NMB preferring, have been characterized. We used a highly potent, selective antagonist of the GRP-preferring receptor, [D-Phe6]bombesine(6-13)-methylester ([D-Phe6]Bn(6-13)OMe), to determine the receptor subtype mediating bombesin-induced secretion of gastrin, GIP, PP, peptide YY (PYY), and insulin, as well as the importance of endogenous bombesin-like peptides in controlling basal secretion of these hormones. Unanesthetized rats received femoral vein infusion of saline, bombesin (10 nmol/kg/h), [D-Phe6]Bn(6-13)OMe (1000 nmol/kg/h), or bombesin plus [D-Phe6]Bn(6-13)OMe. Blood was withdrawn from jugular vein catheters before and 30 min after the start of infusions. Plasma gastrin, GIP, PP, PYY, and insulin were measured by specific radioimmunoassays. [D-Phe6]Bn(6-13)OMe alone reduced basal insulin levels by 28% (p < 0.05) but did not alter basal levels of plasma PP, GIP, PYY, or gastrin (p > 0.05 for each). Bombesin infusion significantly increased plasma levels of each hormone (p < 0.0001 for each). [D-Phe6]Bn(6-13)OMe completely blocked bombesin-induced increases in PP, insulin, and gastrin, and almost completely blocked increases in GIP and PYY (p < 0.01 for each). Our results suggest that (a) exogenous bombesin significantly stimulates PP, insulin, GIP, PYY, and gastrin secretion, (b) bombesin-induced secretion of these hormones is primarily mediated by the GRP-preferring receptor, and (c) an endogenous bombesin-like peptide acting at this receptor subtype plays an important physiological role in control of basal secretion of insulin but not PP, GIP, PYY, or gastrin.     

Variation in expression of a bovine alpha-lactalbumin transgene in milk of transgenic mice

Transgenic mice were produced to study the production of bovine alpha-LA in their milk. A 7.6-kb fragment containing a bovine alpha-LA gene was purified and microinjected into pronuclear stage mouse embryos. This fragment contained 2.0 kb of 5' flanking region, the 1.7-kb coding region, and 2.7 kb of 3' flanking region. Out of 121 potential transgenic founder mice, 3 were identified as being transgenic by the polymerase chain reaction. Multiple mice from the second, third, and fourth generation from each line were milked, and the milk was analyzed using an ELISA assay and Western blots to determine the presence of bovine alpha-LA. Bovine alpha-LA was present at concentrations up to 1.5 mg of protein/ml of mouse milk. The high degree of expression variation between mice within each of the transgenic lines was a characteristic that has not been reported in other studies of transgene expression in milk. Production of bovine alpha-LA in the milk of these transgenic mice showed a high degree of variation both within a lactation and between mice within a line. The bovine alpha-LA concentration in a single line of transgenic mice exhibited as much as a 10-fold variation between mice. Variations as high as 3-fold were detected within a single lactation in the same mouse. These differences in expression appeared to be correlated with mouse milk production; bovine alpha-LA was higher on d 10 and 15 of lactation than on d 5. Transgenic mice that show variation in expression of a bovine gene might offer a unique system for studying quantitative traits in a laboratory model.     

Negative attributional style in seasonal and nonseasonal depression

OBJECTIVE: There is a substantial relationship between dysfunctional cognitions and the clinical course of major depression. This study examined whether this association extends to patients with seasonal affective disorder. METHOD: A revised version of the Attributional Style Questionnaire was used to assess negative attributional style and predict response to treatment in a group of depressed outpatients, 26 with seasonal depression and 30 with nonseasonal, unipolar major depression. RESULTS: Pretreatment scores on negative attributional style did not differ between the patients with seasonal affective disorder and those with nonseasonal depression. Negative attributional style predicted poor response to pharmacotherapy in the nonseasonal depression group but did not predict response to light therapy in the group with seasonal affective disorder. CONCLUSIONS: Dysfunctional cognitions may play a lesser role in seasonal affective disorder than in nonseasonal depression.     

Declining prevalence of cervicovaginal human papillomavirus infection with age is independent of other risk factors

The purpose of this study was to determine whether the addition of small quantities of minor lecithin components (phosphatidylinositol, phosphatidic acid, lysophosphatidylethanolamine, and cholesterol) and Pluronic F68 to lecithin could improve the stability of lecithin-stabilized perfluorocarbon emulsions. Attempts were made to correlate emulsion stability with interfacial properties (tension and charge). Dynamic interfacial tension was determined using a Teflon Wilhelmy plate method [reported previously (1)]. Emulsions were prepared by microfluidization. Microelectrophoresis was used to measure emulsion droplet charge, and photon correlation spectroscopy and Coulter analysis were used to determine emulsion stability as a function of droplet size. Thermal kinetic accelerated stability testing was conducted. Various droplet size parameters were used to compare emulsion stabilities, and an overall stability ranking, based on these parameters, was obtained for each emulsion. Small quantities of additives altered emulsion stability and these data were correlated with interfacial properties and initial droplet diameters. The addition of cholesterol to lecithin resulted in the most stable perfluorocarbon emulsion.