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An automated multi-pumping flow system is proposed for the chemiluminometric determination of ascorbic acid in pharmaceutical formulations, relying on the ability of semiconductor nanocrystals to generate short-lived reactive species upon photo-irradiation. A photo-unit based on visible-light-emitting diodes is used to photo-excite cadmium telluride (CdTe) quantum dots capped with glutathione, leading to the generation of radicals that react with luminol under alkaline conditions, yielding the chemiluminescence. Ascorbic acid acts as a radical scavenger, preventing the oxidation of luminol, thus ensuring a concentration-dependent chemiluminescence quenching. After system optimization, a linear working range of 5.0 × 10-7 to 5.0 × 10-6 mol/L ascorbic acid (r = 0.9967, n = 5) was attained, with a detection limit of 3.05 × 10-7 mol/L and a sampling rate of 200/h. The flow system was applied to the analysis of pharmaceutical formulations and the results were in good agreement with those obtained by the reference titrimetric procedure (RD< ± 4.3%, n = 7). [ABSTRACT FROM AUTHOR]

In 6 normal volunteers given single oral doses of 250, 500 and 1000 mg ticlopidine (T), the peak plasma level of unchanged drug was reached after about 2 h. There was no correlation between the plasma T level and its inhibitory effect on platelet function, expressed as % inhibition of ADP-induced aggregation. By means of HPLC and GC/MS significant concentrations of T were demonstrated in washed red cells, platelets and neutrophils, with a marked difference in the time course of the appearance of cell-associated drug. The time course of platelet-associated T very accurately fitted that of the antiaggregatory activity. After subacute oral administration (250 mg b. d. for 7 days), the maximum effect on platelet function was observed after 3 to 4 days, when a significant concentration of platelet-associated T had been reached. The pharmacological effect persisted as long as drug was detectable in platelet. An in vitro study strongly suggested that the antiaggregating effect was retained by treated washed platelets but not by treated plasma. It is suggested that the platelet compartment represents the pharmacological target of T via a specific uptake system. [ABSTRACT FROM AUTHOR]

In the past few years there has been increasing interest in the role of the vascular endothelium as an active modulator of biological responses. Endothelial cells exert antithrombotic activity by the release of prostacyclin [23] and adenine nucleotides [16], the availability on the cell surface of heparin-like substances [3], and thrombomodulin-mediated activation of protein C [8]. In addition, endothelium is involved in the regulation of fibrinolysis by releasing soluble factors, such as tissue plasminogen activator (tPA; [10]) and plasminogen activator inhibitor (PAI; [22, 11]), as well as in the control of vascular responsiveness by the production of smooth muscle relaxing and contracting factors. Endothelial cells have also been shown to synthesize and to express procoagulant activities [18]. Many data on endothelial cell functions has been obtained from two experimental models, namely endothelial cell cultures and perfused segments of animal and human vessels. Both are subject to methodological criticism since they only represent in part in vivo conditions, and the necessary experimental manipulations and laboratory procedures greatly modify the naturally occurring cellular functions. In order to overcome such difficulties as far as possible, a new in vivo model has been employed to provide easily assessable and reliable data on the properties of endothelial cells in man. A venous segment was isolated functionally by cannulating a dorsal vein in the hand and a cubital vein in the same arm. Changes observed ex vivo in blood from the cubital vein following infusion into the hand vein of an active drug, can mainly be attributed to its local effect on the venous wall. At the same time, a cubital vein in the other arm was cannulated in order to provide information to distinguish systemic from regional effects. [ABSTRACT FROM AUTHOR]

Previous publications have revealed that a pretreatment of lignocellulosic wastes is necessary if they are to be employed as the hydrocarbon source of single cell protein production. A hot alkaline treatment is the most common. We have treated sugar cane bagasse pith with 1% NaOH solution at room temperature, at a NaOH/pith ratio of 10%. Different contact times were used in the experiments. The shortest contact period required for maximum protein production was 24 h at 25° C. A mixed culture of Cellulomonas sp. and Bacillus subtilis was used in the experiments. The values obtained for hemicellulose and cellulose in the treated pith did not differ greatly from those of untreated pith, in contrast the amount of lignin was 33% lower in the treated pith. The effect of reutilization of the alkaline liquor used for the pretreatment of pith upon protein production was also investigated. With four recyclings, there was a NaOH saving of 34.4 kg per 100 kg produced protein as compared to when the liquor was only used once. The quality of the resulting effluents, as measured by the chemical oxygen demand (COD), proved to be very similar for both types of treatment. [ABSTRACT FROM AUTHOR]

In the first part of the study five healthy volunteers were submitted toi. v. infusion of 0.2 mM. kg b.w. of calcium gluconate over 20 min. Total calcium (atomic absorption method), ionized calcium (ion-selective electrode method) and adenosine (HPLC technique) were measured at the following times: 0 (basal), 5, 10, 15, 20 (end of infusion), 25, 30, 35, and 50 min. The increase in total and ionized calcium serum levels was associated with a significant increase in adenosine plasma levels (from 207 ±41 to 362 ±63 nM. 1 −1, P<0.001). Since the increase in adenosine plasma levels, obtained either with adenosine or dipyridamole (an adenosine reuptake inhibitor), has been used to test the coronary reserve in coronary artery disease (CAD) patients, in the second part of the study we compared the effects of calcium infusion with dipyridamole in 15 subjects. Pharmacological stress tests were evaluated by monitoring two-dimensional echocardiography and ECG. Ten patients had positive results with both the dipyridamole stress test and the calcium infusion. Our results show that calcium infusion induces an increase in adenosine plasma levels that can elicit a dipyndamole-like coronary steal, thus suggesting the central role of extracellular adenosine in myocardial ischaemia. [ABSTRACT FROM PUBLISHER]

The plasma kinetics of adenosine was investigated in healthy volunteers after a 1 minute infusion of 2.5, 5 and 10 mg (38, 79 and 148 μg·kg respectively) and after infusion of 200 μg·kg in 10 min followed by 400 μg·kg in 10 min. As the dose in the 1 min infusion study was increased the mean CL of adenosine decreased (10.7, 4.70 and 4.14 l·min, respectively), its mean half-life increased (0.91, 1.24 and 1.86 min, respectively), and the mean volume of distribution did not show any clear trend (8-13 l). After the 20 minute infusion the plasma level of adenosine reached a peak value comparable to that observed after infusion of 5 mg in 1 min (about 0.5 μg·ml), but the mean clearance and half-life were significantly different (12.1 l·min and 0.63 min respectively). In all the subjects the plasma concentration of adenosine had returned to the baseline value in 5-15 min after the end of the infusion. [ABSTRACT FROM AUTHOR]

The prevalence of insulin allergy has considerably decreased with the availability of human recombinant insulins, and the disorder is now rare, although well described. Insulin allergy may present as immediate-type IgE-mediated local or systemic anaphylactic reaction, as delayed-type hypersensitivity, or, more rarely, as serum sickness. The favorable course of the severe insulin allergy, even when Lyspro was administered by pump, emphasizes the importance of this new insulin analog as a therapeutic alternative, at least in non-IgE-mediated hypersensitivity.