Measurement of basal tear turnover using a standardized protocol

Background: The aim of this study was to compare basal tear turnover values of healthy volunteers in different countries. Methods: Healthy volunteers aged between 20 and 70 years were selected in three European cities. Basal tear turnover values were calculated according to a standardized protocol from the decay of the fluorescein concentration in tears after instillation of 1-l drop of fluorescein in the conjunctival sac. Fluorescein concentration was measured with identical commercial fluorophotometers. A monoexponential decay of fluorescein was assumed to represent basal tear flow. Results: The mean tear turnover values were 13.1%/ min ± 4.6 SD (n=4), 16.0%/ min ± 5.2 SD (n=24) and 17.5%/ min ± 3.4 SD (n = 20) in Clermont-Ferrand (France), Leiden (The Netherlands) and Madrid (Spain), respectively. The differences between the values were not significant (Mann-Whitney test P > 0.09). Conclusions: The tear turnover in the different cities was similar. The methods used were simple and the software easy to use.Concerted Action, supported in part by the European Commission, on Ocular Fluorometry: Standardization and Instrumentation Development of the 4th European Community Medical and Health Research Programme (No. MR 4*/0314/P).     

Catheter entrapment by atrial suture during minimally invasive port-access cardiac surgery

PURPOSE: The port-access approach allows surgeons to perform heart operations through small intercostal openings, or "ports". This technique requires new skills for anesthesiologists. A pulmonary artery venting (PAV) catheter and, in some cases, a coronary sinus catheter (for administration of retrograde cardioplegia) are positioned with the aid of fluoroscopy and transesophageal echography (TEE). Both catheters have a wider diameter than the more commonly used conventional PA catheter and present distinctive features. We report a case in which a pulmonary artery venting catheter was entrapped by a suture during a port-access procedure. CLINICAL FEATURES: A 35-yr-old man with severe mitral valve insufficiency was scheduled for valve repair. After a successful bypass procedure, resistance was felt while attempting to withdraw the PAV catheter. On fluoroscopy, fixation of the catheter at the heart level was established and perforation by suture was confirmed after injection of a contrast agent. Because of the risk of cardiac wall rupture and tamponade, the thorax was reopened. After release of some atrial sutures, the catheter could be withdrawn easily. Transfixion by a suture was confirmed by visual examination. CONCLUSION: The more frequent use of a PAV catheter in minimally invasive cardiac surgery with the port-access technique should remind the anesthesiologist of the higher risk of entrapment by surgical sutures. Surgeons should be aware of the risk of accidentally transfixing this catheter during closure of the atriotomy via the port.     

Induction of eotaxin expression and release from human airway smooth muscle cells by IL-1beta and TNFalpha: effects of IL-10 and corticosteroids.

Eotaxin is a novel C-C chemokine with selective chemoattractant activity for eosinophils. We determined whether eotaxin could be produced by human airway smooth muscle (HASM) cells in culture and examined its regulation by interleukin-10 (IL-10) and the corticosteroid, dexamethasone. Stimulation of the cells with interleukin-1beta (IL-1beta) or tumour necrosis factor (TNFalpha) each at 10 ng ml(-1) induced the release of eotaxin protein with maximal accumulation by 24 h. Interferon-gamma (IFNgamma) alone at 10 ng ml(-1) had no effect and there was no synergy between these cytokines on the release of eotaxin. Reverse phase high performance liquid chromatographic (HPLC) analysis of supernatents from cells treated with TNFalpha (10 ng ml(-1) for 96 h showed immunoreactivity to eotaxin which eluted with the expected retention time of 34.5-35 min. Both IL-1beta and TNFalpha-induced release of eotaxin was not inhibited by dexamethasone (1 microM), however IL-10 (10 ng ml(-1)) had a significant inhibitory effect. Dexamethasone and IL-10 did not inhibit the induction of eotaxin mRNA induced by IL-1beta or TNFalpha. Thus, human airway smooth muscle cells can release eotaxin and could be an important source of chemokine production during airway inflammatory events.     

Ultrasound Densitometric Analysis: Comparison Between an Online Digital Acquisition Acoustic Program and an Offline Analog Program

Videodensitometric analysis of myocardial contrast echocardiography is traditionally performed off line. Recently, an online contrast ultrasound analysis system, Acoustic Densitometry (Hewlett-Packard), was introduced. We compared pixel intensities acquired with Acoustic Densitometry to pixel intensities derived from videodensitometry. A tissue phantom was imaged in phase I using three transducer frequencies (2.5, 3.5, and 5.0 MHz). In phase II, an in vitro flowing tube model with various concentrations of Albunex® was imaged at two flow rates, 0.6 and 1.2 m/sec, and at two transducer frequencies, 2.5 and 3.5 MHz. The relationship between pixel intensities yielded by the two systems for identical ultrasound signals was determined with linear regression. Intensities derived with Acoustic Densitometry strongly correlated with those derived from the offline videodensitometry system. The intensities were related by a predictive multiplicative factor based on display characteristics of the two systems. These results suggest that semiquantitative, online perfusion analysis with Acoustic Densitometry is as sensitive as analysis offline with videodensitometry.     

Effects of selective phosphodiesterase inhibitors on platelet-activating factor- and antigen-induced airway hyperreactivity, eosinophil accumulation, and microvascular leakage in guinea pigs

There is currently interest in the potential use of selective inhibitors of cyclic nucleotide phosphodiesterases (PDE) in the treatment of asthma. In this study we examined the effects of three selective PDE inhibitors, milrinone (PDE III), rolipram (PDE IV) and zaprinast (PDE V), on the broncoconstriction produced by antigen and histamine, the airway hyperreactivity and microvascular leakage after aerosol exposure to platelet-activating factor (PAF) and antigen, and the antigen-induced eosinophil infiltration in guinea-pig lung. Inhaled rolipram (0.01–10 mg ml^–1) inhibited dose dependently the bronchospasm produced by aerosol antigen (5 mg ml^–1) an anaesthetised, ventilated guinea-pigs. Rolipram (10 mg ml^–1) produced maximal inhibition of antigen-induced bronchoconstriction but only partial inhibition of the response to aerosol histamine (1 mg ml^–1). Milrinone and zaprinast (each 10 mg ml^–1) showed weak, or no, inhibitory effects against bronchoconstriction produced by aerosol antigen or histamine. Pretreatment with rolipram (10 mg kg^–1, i.p.) prevented airway hyperreactivity to histamine which develops 24 h after exposure of conscious guinea-pigs to aerosol PAF (500 g ml^–1) or antigen (5 mg ml^–1). The pulmonary eosinophil infiltration obtained with 24 h of antigen-exposure was inhibited by rolipram. In contrast, milrinone and zaprinast (each 10 mg kg^–1, i.p.) failed to reduce either the airway hyperreactivity of the eosinophil accumulation in these animals. Rolipram (1–10 mg ml^–1) reduced the extravasation of Evans blue after aerosol PAF (500 g ml^–1) at all airway levels while a lower dose (0.1 mg ml^–1) was only effective at intrapulmonary airways. Rolipram (0.01–1 mg ml^–1) markedly reduced airway extravasation produced by inhaled antigen (5 mg ml^–1). Zaprinast (1–10 mg ml^–1) was also effective against airway microvascular leakage produced by aerosol PAF or antigen while milrinone (10 mg ml^–1) had no antiexudative effect. These data support previous suggestions that pharmacological inhibition of PDE IV results in anti-spasmogenic and anti-inflammatory effects in the airways and may be useful in the treatment of asthma.     

Restraint-induced stress ulcer. I. Hypothalamic,urinary, and adrenal biochemical studies

The purpose of these experiments was to study the incidence of stress ulcers in restrained rats and to correlate it with hypothalamic and adrenal cortical and medullary activity, with and without vagotomy. A total of 217 adult rats were used, grouped into 56 sets, and distributed at random in 5 experimental groups. Restraint was followed by a 79% incidence of ulceration in the glandular portion of the gastric mucosa. Vagotomy made these worse (p<0.01). Hypothalamic levels of catecholamines and serotonin showed no significant changes. Urinary measurements revealed decreased excretion of 17-ketosteroids (p<0.001), increased excretion of uropepsinogen (p<0.01), and no significant changes in vanillylmandelic acid among the rats submitted to immobilization. In the adrenal glands of stressed animals, there was a decreased level of catecholamines (p<0.01) and no significant changes in corticosteroid content (17-ketosteroids). These results suggest that hypothalamic stimulation and the participation of the adrenal glands are not essential factors in the pathogenesis of restraint-induced experimental stress ulcer.     

Effects of metoprolol on action potential and membrane currents in guinea-pig ventricular myocytes

Summary The effects of the beta-adrenoceptor antagonist metoprolol on action potentials and membrane currents were studied in single guinea-pig ventricular myocytes. The experiments were carried out using the nystatin-method of whole-cell technique. This method was used in order to prevent the run-down of the calcium current. Metoprolol at concentrations of 10–100 mol/l shortened action potential in a dose-dependent way. The drug only decreased resting membrane potential at a concentration of 100 mol/1 in two out of five cells. Under voltage-clamp conditions, metoprolol blocked the high threshold calcium current at concentrations of 30 and 100 mol/l to 82 ± 4% and 73 ± 5% from control, respectively. The drug decreased the inward rectifying potassium current in a concentration-dependent manner. This effect was evident for inward current at voltages negative to the apparent reversal potential and for outward current at voltages between –30 and –80 mV. This blocking effect on the inward rectifying potassium current can explain the effect on resting membrane potential. At voltages positive to –30 mV metoprolol increased a time-independent outward current. This metoprolol-enhanced outward current was blocked by barium and cesium. This result suggests that the metoprolol-enhanced current is carried by potassium. The current component enhanced by metoprolol was not sensitive to glibenclamide and tetraethylammonium applied externally, which suggests that the adenosine triphosphate-sensitive channel is not the target of metoprolol. The activation of this time-independent outward current by metoprolol and the blocking effects on the calcium current seem to explain the shortening in action potential induced by the drug. Send offprint requests to J. Sánchez-Chapula at the above address     

The conduct of in vitro and in vivo drug-drug interaction studies: a Pharmaceutical Research and Manufacturers of America (PhRMA) perspective.

Current regulatory guidances do not address specific study designs for in vitro and in vivo drug-drug interaction studies. There is a common desire by regulatory authorities and by industry sponsors to harmonize approaches, to allow for a better assessment of the significance of findings across different studies and drugs. There is also a growing consensus for the standardization of cytochrome P450 (P450) probe substrates, inhibitors and inducers and for the development of classification systems to improve the communication of risk to health care providers and to patients. While existing guidances cover mainly P450-mediated drug interactions, the importance of other mechanisms, such as transporters, has been recognized more recently, and should also be addressed. This article was prepared by the Pharmaceutical Research and Manufacturers of America (PhRMA) Drug Metabolism and Clinical Pharmacology Technical Working Groups and represents the current industry position. The intent is to define a minimal best practice for in vitro and in vivo pharmacokinetic drug-drug interaction studies targeted to development (not discovery support) and to define a data package that can be expected by regulatory agencies in compound registration dossiers.