Magnetic resonance velocity imaging of liquid and gas two-phase flow in packed beds.

Single-phase liquid flow in porous media such as bead packs and model fixed bed reactors has been well studied by MRI. To some extent this early work represents the necessary preliminary research to address the more challenging problem of two-phase flow of gas and liquid within these systems. In this paper, we present images of both the gas and liquid velocities during stable liquid-gas flow of water and SF(6) within a packing of 5mm spheres contained within columns of diameter 40 and 27 mm; images being acquired using (1)H and (19)F observation for the water and SF(6), respectively. Liquid and gas flow rates calculated from the velocity images are in agreement with macroscopic flow rate measurements to within 7% and 5%, respectively. In addition to the information obtained directly from these images, the ability to measure liquid and gas flow fields within the same sample environment will enable us to explore the validity of assumptions used in numerical modelling of two-phase flows.

Investigating the role of alienation in a multicomponent model of juvenile delinquency.

Research findings indicate that there are multiple causal pathways to delinquency. A multicomponent model of delinquency was developed to explore systematically the interrelationships of psychosocial variables and their relationships to delinquent behaviour. Most importantly, alienation was tested for its ability to act as a core mediating predictor variable. One hundred and fifty-two adolescents, 78 females and 74 males, completed a battery of questionnaires designed to assess each of the variables in the proposed model. Several salient pathways to delinquency were identified. They include environmental and person-centred factors. Alienation, when operationalized as a general construct, was not found to be a necessary mediating predictor variable. "Societal" alienation, on the other hand, was shown to have important explanatory power. Re-examining the model within a large-scale, time-extended study could inform programmes for the prevention and early intervention of delinquent behaviour.

Three sample preparation protocols for polymerase chain reaction based detection of Cryptosporidium parvum in environmental samples.

Cryptosporidium parvum is a protozoan parasite responsible for an increasing number of outbreaks of gastrointestinal illness worldwide. In this report, we describe development of sample preparation protocols for polymerase chain reaction (PCR)-based detection of C. parvum in fecal material and environmental water samples. Two of these methods were found adequate for isolation of Cryptosporidium DNA from filtered water pellet suspensions. The first involved several filtration steps, immunomagnetic separation and freeze-thaw cycles. The second method involved filtration, addition of EnviroAmp lysis reagent, freeze-thaw cycles and precipitation of the DNA with isopropanol. Using nested PCR, we detected 100 oocysts/ml of filtered water pellet suspension, with either of the above sample preparation procedures. Nested PCR increased sensitivity of the assay by two to three orders of magnitude as compared to the primary PCR. The detection limit for seeded fecal samples was 10-fold higher than for filtered environmental water pellet suspension. Nested PCR results showed 62.4 and 91.1% correlation with immunofluorescence assay (IFA) for fecal samples and filtered environmental water pellet suspensions, respectively. This correlation decreased to 47.2% and 44.4%, respectively, when only IFA positive samples were analyzed. However, in fecal samples contaminated with a high number (> 10(5)/g) of C. parvum oocysts, this correlation was 100%.

Preliminary study of the disposition in man of acebutolol and its metabolite, diacetolol, using a new stereoselective hplc method.

A new stereospecific hplc method that is capable of simultaneously quantitating the S-(-)- and R-(+)-enantiomers of acebutolol and its major metabolite, diacetolol, in plasma and urine, is described. When applied to the assay of biological fluids collected during single and chronic oral dosing with acebutolol (Sectral), this procedure failed to reveal any important stereoselectivity in the disposition of either acebutolol or diacetolol in man. This may occur because acebutolol is metabolized by hydrolysis and N-acetylation, whereas the other beta-blockers which exhibit some degree of stereoselective disposition (e.g. metoprolol and propranolol) are primarily metabolized by oxidation.

The penetration of trimethoprim and sulphamethoxazole into synovial fluid.

A group of six patients with non-infected synovial effusions requiring diagnostic or therapeutic aspiration, were given a short oral course of 'Septrin' (two tablets bd for two doses, each tablet containing 80 mg of trimethoprim plus 400 mg of sulphamethoxazole). Serum and synovial fluid (SF) were sampled frequently following antibiotic administration. It was found that concentrations of trimethoprim in SF approached serum levels after a short lag time (about 3 h) and thereafter approximated to the serum levels, whereas sulphamethoxazole did not as readily penetrate into SF. With the regimens used MIC levels for trimethoprim were achieved in SF, which suggests that this drug could be usefully prescribed in normal doses for the treatment of septic arthritis due to bacterial infection.

Acebutolol and coronary artery surgery. Plasma levels following oral pre-operative treatment.

Plasma levels of acebutolol and its major human metabolite, diacetolol, were determined before, during and after aortocoronary bypass grafting in 10 patients who had received a chronic oral regimen of acebutolol 200 mg t.d.s. for at least 6 days before surgery, a 200 mg dose with the premedication and 5-10 mg intravenously immediately before intubation. It was found that this regimen produced beta-adrenoceptor antagonist levels which were within the range in which attenuation of hypertension and tachydysrhythmia occurs. These effective plasma levels were sustained throughout surgery and persisted into the early recovery period.

The penetration of metronidazole into synovial fluid.

Six patients with non-infected synovial effusions, associated either with inflammatory or degenerative arthropathy and requiring diagnostic or therapeutic aspiration, were given a short course of 400 mg metronidazole (Flagyl) 8-hourly for 3 doses. Serum and synovial fluid (SF) were sampled frequently during this time, and assayed for metronidazole by a specific high pressure liquid-chromatographic method. It was found that concentrations of metronidazole in SF reached those in serum after a short time-lag, and thereafter approximated to the serum concentration. With this regimen, metronidazole concentrations were readily achieved in synovial fluid, above the minimum inhibitory concentrations for most susceptible anaerobes. These results indicate that the drug freely enters the synovial fluid and suggests that metronidazole would prove effective in the treatment of septic arthritis due to anaerobic bacteria.

Serum, saliva, and sputum levels of metronidazole in acute exacerbations of chronic bronchitis.

We have evaluated the absorption and the penetration of metronidazole into the bronchial secretions and saliva in acute infective exacerbations of chronic bronchitis. Seventeen patients were given 400 mg orally three times daily for seven days and "steady state" levels were measured in serum, saliva, and sputum on the last day of treatment. Mean levels in the three biological fluids were not significantly different. Higher metronidazole levels in sputum tended to occur in patients with higher serum levels. In all but one patient, levels in serum and saliva were well within the therapeutic range. We conclude that this oral regimen results in therapeutic tissue levels in acute exacerbations of chronic bronchitis.

The pharmacokinetics of acebutolol in man, following the oral administration of acebutolol HCl as a single dose (400 mg), and during and after repeated oral dosing (400 mg, b.d.).

The pharmacokinetics of acebutolol have been studied in eight healthy male volunteers following the oral administration of acebutolol hydrochloride ('Sectral', May & Baker) as a single dose (400 mg), and during and after repeated oral dosing (400 mg, b.d. for 56 days). Following single dose administration, considerable inter-subject variation in plasma levels of parent drug and the major metabolite, diacetolol, was evident. Acebutolol appeared to be eliminated from plasma in a bi-phasic manner, and this was confirmed from urinary excretion rate data. Mean initial and terminal half-lives of about 2 and 11 h, respectively, were determined. Plasma levels of diacetolol were greater than those of parent drug from 3 to 4 h following dose administration. Total urinary excretion of diacetolol was generally greater than that of acebutolol. During repeated dosing, steady-state plasma levels of acebutolol and diacetolol were achieved in 6 volunteers. Acebutolol did not appear to stimulate or inhibit its metabolism.