Circle-ellipse discrimination in man and monkey

Humans were instructed and monkeys trained to press a panel with a back-projected circle among seven panels with identical ellipses. Ellipses with a smaller or larger ratio between their axes were presented according to a titration schedule which aimed at 75 per cent correct responses. Both the best performance and the range was the same in humans and monkeys: in humans performance declined with age. The threshold was the same with horizontal and vertical ellipses. Chance performance when all stimuli were circles showed that extraneous cues were absent.     

Concentrations of some metabolites in the aqueous humour of human senile cataractous eyes.

Glucose, pyruvate, l-lactate, and citrate concentrations of the aqueous humour were examined in 51 patients aged 54-87 years with senile cataracts, and in one patient with a clear lens. Furthermore, the ratios of glucose in aqueous/glucose in plasma and citrate in aqueous/citrate in plasma were investigated. Among the parameters recorded, age dependence could only be demonstrated for glucose concentrations in the aqueous humour, as this parameter decreases with increasing age. However, a chance significance because of multipleignificance tests cannot be left out of account in this material. The parameters in question are unfit for an evaluation of possible changes in the energy metabolism of the lens in relation to cataract development because no significant differences were found between concentrations and ratios in different clinical types of cataract. Also, considerable ranges of variation were recorded.     

Glucose, pyruvate, L-lactate, and citrate concentrations in the aqueous humour of fasting rabbits in relation to age.

Results are reported of determinations of glucose, pyruvate, l-lactate and citrate concentrations in aqueous humour from 42 fasting albino rabbits aged from 8 months to 9 years. The glucose concentrations decreased significantly with increasing age. The pyruvate and l-lactate concentrations as well as the ratios of l-lactate/pyruvate did not change significantly with age. However, the pyruvate concentrations were higher and the l-lactate/pyruvate ratios were lower in the 2-year-old rabbits than in the others. The citrate concentrations were found to rise with increasing age. Because of wide ranges of variation between individuals of the same age groups, the parameters in question have limited value in the evaluation of the energy metabolism of the anterior eye segment.     

Circle-elipse discrimination in monkeys: comparison of titration schedules with the method of limits

In order to make a direct comparison, psychometric functions were derived from two titration schedules and from the method of limits. Three vervet monkeys were reinforced with food pellets for choosing a response key with a back-projected circle from among 7 keys with identical elipses. Elipse ratios from 0.400 to 0.985 were available in 18 discrete steps. The schedules were tested in this sequence: (1) a titration schedule with different up-and-down transformed response rules. Training began with a rule of 3:1 indicating that after three correct responses the next trial presented elipse ratios one step higher. A change to a lower ratio occurred after one incorrect response. Subsequently, up-and-down rules from 1:3 to 9:1 were tested, one rule per session. (2) the method of limits. One elipse ratio was tested per session first in a sequence of increasing then of decreasing ratio. (3) a titration schedule with sequential likelihood ratio tests. A target probability of correct responses was approached by deciding after each trial whether to change to a larger or to a smaller elipse ratio. Psychometric functions derived from schedules 1 and 2 coincided. Schedule 3 produced oscillations in the difficulty of the presented stimuli. The conclusion is that discrete trial titration schedules with different up-and-down transformed response rules provided reliable measures of threshold in a visual shape discrimination. Performance was more stable and the programming simpler with this schedule than with the sequential likelihood ratio test.     

Use of colonic eicosanoid concentrations as predictors of relapse in ulcerative colitis: double blind placebo controlled study on sulphasalazine maintenance treatment.

To establish whether concentrations of eicosanoids determined by equilibrium in vivo dialysis of faeces and equilibrium in vivo dialysis of rectum might predict a relapse in ulcerative colitis, 23 patients with completely inactive disease, maintained on sulphasalazine, stopped treatment and entered a prospective study. Concentrations of prostaglandin E2 were determined by radioimmunoassay on purified faecal and rectal dialysates at entry, at two weeks, and at two, six, and 12 months. If the above concentrations exceeded control concentrations (0.5 ng/ml and 1.0 ng/ml in faecal and rectal fluid, respectively) at any study day, the patient was allocated at random to double blind treatment with sulphasalazine 2 g/day, or placebo for six months. A relapse, defined as recurrence of symptoms accompanied by endoscopic inflammation occurred in none of six and in four of five patients allocated to sulphasalazine and placebo, respectively (p less than 0.05). In no case a normal rectal prostaglandin E2 concentration was associated with a relapse in the short term, but only two of 12 patients observed passively remained in remission. In retrospect, leukotriene B4 was a less sensitive predictor of relapse than prostaglandin E2. We conclude that raised concentrations of prostaglandin E2 in rectal dialysis fluid identify patients with a substantial risk of relapse.     

Bambuterol: clinical effects of three doses of bambuterol once daily in asthmatic patients

Twenty-two asthmatics received bambuterol solution, a terbutaline pro-drug, once every evening. The following doses were each given orally for 7 days in a double-blind cross-over study: 0.185, 0.270 and 0.400 mg/kg. Bambuterol 0.270 mg/kg was preferable regarding clinical effects and side effects. The plasma concentration of generated terbutaline showed a slow linear decrease at all doses. Tests of two methods for objective measurements of tremor in five patients did not add any new data compared with the subjective recordings.     

Specific immunoassays for detection of intact and cleaved forms of the urokinase receptor

BACKGROUND: The cell surface receptor (uPAR) for urokinase plasminogen activator (uPA) is a strong prognostic marker in several types of cancer. uPA cleaves the three-domain protein uPAR(I-III) into two fragments: uPAR(I), which contains domain I; and uPAR(II-III), which contains domains II and III. Established immunoassays measure a combination of uPAR forms. Our aim was to design immunoassays for specific quantification of the individual forms of uPAR. METHODS: Using appropriate combinations of epitope-mapped monoclonal antibodies (Mabs) for capture and europium-labeled detection Mabs, we designed two-site sandwich time-resolved fluorescence immunoassays (TR-FIAs): TR-FIA 1 to measure uPAR(I-III) alone; TR-FIA 2 to measure both uPAR(I-III) and uPAR(II-III); and TR-FIA 3 to measure uPAR(I). To avoid detection of uPAR(I-III) in TR-FIA 3, we used a combination of the peptide uPAR antagonist AE120 and a domain I antibody, R3. AE120 blocks the binding of R3 to uPAR(I-III). In contrast, AE120 does not interact with liberated domain I and therefore does not interfere with the binding of R3 to uPAR(I). RESULTS: The limits of quantification (CV <20%) determined by adding the proteins to uPAR-depleted plasma were <3 pmol/L in all three assays. The interassay CVs in plasma with added analytes were <11%, and recoveries were between 93% and 105%. Cross-reactivities of purified proteins in the three TR-FIAs were no more than 4%. Studies on chymotrypsin cleavage of uPAR and size-exclusion chromatography of plasma with and without added protein further supported the specificity of the assays. CONCLUSIONS: The three novel TR-FIAs accurately quantify uPAR(I-III) alone, uPAR(I-III) together with uPAR(II-III), and uPAR(I), respectively, in biological samples, including plasma, and thus are well suited for studies of the diagnostic and prognostic value of individual uPAR forms in cancer patients.     

Volume adjustment of lung density by computed tomography scans in patients with emphysema

PURPOSE: To determine how to adjust lung density measurements for the volume of the lung calculated from computed tomography (CT) scans in patients with emphysema. MATERIAL AND METHODS: Fifty patients with emphysema underwent 3 CT scans at 2-week intervals. The scans were analyzed with a software package that detected the lung in contiguous images and subsequently generated a histogram of the pixel attenuation values. The total lung volume (TLV), lung weight, percentile density (PD), and relative area of emphysema (RA) were calculated from this histogram. RA and PD are commonly applied measures of pulmonary emphysema derived from CT scans. These parameters are markedly influenced by changes in the level of inspiration. The variability of lung density due to within-subject variation in TLV was explored by plotting TLV against PD and RA. RESULTS: The coefficients for volume adjustment for PD were relatively stable over a wide range from the 10th to the 80th percentile, whereas for RA the coefficients showed large variability especially in the lower range, which is the most relevant for quantitation of pulmonary emphysema. CONCLUSION: Volume adjustment is mandatory in repeated CT densitometry and is more robust for PD than for RA. Therefore, PD seems more suitable for monitoring the progression of emphysema.     

Omeprazole and ranitidine in treatment of reflux oesophagitis: double blind comparative trial

One hundred and sixty two patients with endoscopically proved reflux oesophagitis stratified for severity, 66 with grade 1 disease (erythema and friability) and 96 with grade 2 or 3 disease (including erosions or ulcerations), were allocated at random to double blind treatment with omeprazole 40 mg in the morning or ranitidine 150 mg twice daily for up to 12 weeks. A patient could be evaluated sooner if symptomatic relief and endoscopically normal mucosa (grade 0) were noted after four to eight weeks' treatment. Patients treated with omeprazole responded significantly more rapidly than those treated with ranitidine (p less than 0.0001), cumulative healing rates at four, eight, and 12 weeks being 90%, 100%, and 100% respectively for those with grade 1 disease and 70%, 85%, and 91% respectively for those with grade 2 or 3 disease in the omeprazole group. Corresponding rates in the ranitidine group were 55%, 79%, and 88% (grade 1) and 26%, 44%, and 54% (grade 2 or 3). Relief of the major symptoms of heartburn, regurgitation, and dysphagia and improvements in the histological appearance of the mucosa occurred earlier and were again more pronounced during treatment with omeprazole than with ranitidine. This observed superiority of omeprazole 40 mg in the morning over ranitidine 150 mg twice daily in the short term treatment of reflux oesophagitis was obtained without major clinical or biochemical side effects, but further research is needed into longer term use of omeprazole and the effects of the acid inhibition it induces.