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Biomedical subjects

N Veall

Publications and source records attributed to N Veall.

At least 37 records · Page 2Linked to original sources
PubMed1983

77Br-p-bromospiperone: a ligand for in vivo labelling of dopamine receptors.

A high striatum: cerebellum ratio of 77Br-p-bromospiperone (77Br-BrSp) was observed in rat brain following tail vein injection of the drug. Striatal 77Br-BrSp was stereospecifically displaced by the isomers of flupenthixol. After chronic haloperidol administration striatal dopamine receptor supersensitivity was demonstrated both by increased 3H-spiperone binding to striatal membranes in vitro and by increased striatal 77Br-BrSp content. These results confirm and extend previous findings and enhance interest in the use of 77Br-BrSp for the in vivo assessment of central dopamine receptors in man.

Animals↗
PubMed1983

A persistent defect in intestinal permeability in coeliac disease demonstrated by a 51Cr-labelled EDTA absorption test.

In the 24 h after ingestion of 100 microCi of 51Cr-labelled EDTA (edetic acid), controls (22) excreted less than 2.5% of the dose, whereas patients with coeliac disease in relapse (6) excreted between 4.7% and 14.7%. In 10 patients with coeliac disease in complete clinical and histological remission, excretion of 51Cr-labelled EDTA was between 3.0% and 12.7% of the dose. This indicates a persistent or primary defect of intestinal permeability in these patients and confirms previous in vitro results. The reproducibility, safety, simplicity, and accuracy of the procedure suggest that it may be suitable as a routine screening test for coeliac disease.

Adolescent↗
PubMed1983

Sequential studies of oxalate dynamics in primary hyperoxaluria.

We have measured the total plasma clearance, renal clearance and equilibrium distribution volume of [14C]oxalate, and the urinary oxalate excretion rate and plasma oxalate levels at approximately 6 months intervals for up to 2.5 years in five patients with primary hyperoxaluria. The renal clearance and distribution volumes of [99mTc]DTPA (diethylenetriaminepenta-acetate) were measured simultaneously to provide estimates of glomerular filtration rate (GFR) and extracellular fluid volume (ECF). The same measurements were made on each of five normal volunteers. Clearances and distribution volumes were measured with a modified single injection technique. The oxalate clearance was two to three times the simultaneously measured GFR in the patients and control subjects. The renal clearance of oxalate was less than the total plasma clearance in the patients. The oxalate distribution volume was approximately 1.5 times the ECF in both the patients and controls. Only small changes were observed over a 2.5 years period in these particular patients. The plasma oxalate concentration was derived from the urinary oxalate excretion rate and the plasma [14C]oxalate clearance. It was raised in the patients. The oxalate removal rate was derived from the total plasma clearance and the plasma oxalate concentration.

Adolescent↗
PubMed1981

Microprocessor crosstalk correction in multiple-detector gamma counters.

A method for compensating for crosstalk between nuclear counters and its application to a multidetector gamma counter is described. The standardisation procedure employed measures the relative efficiency of each detector for a sample within that detector and for the same detector when the sample is located in each of the other detectors. Results with a 12-element detector system show that the stored calibration data obtained in this way can be applied successfully to correct the observed count rates for crosstalk as well as detector sensitivity differences when using gamma emitters having energies up to 1.3 MeV.

Computers↗
PubMed1981

Dosimetry of renal radiopharmaceuticals: the importance of bladder radioactivity and a simple aid for its estimation.

The contribution from radioactivity in bladder contents to dose commitments to the embryo, ovaries, red marrow, kidney, bladder wall and total body has been estimated for various renal radiopharmaceuticals, assuming a bladdervoiding period of 3.5 h. For hippuran and GFR agents this contribution is 70-97% of the embryo dose and 50-93% of the ovary dose. The embryo dose exceeds the ovary dose by a factor of two or more. For the radiopharmaceuticals with no significant kidney retention, the surface dose to the bladder wall is higher, by more than an order of magnitude, than doses to other organs and is largely responsible for the effective dose equivalent exceeding the estimated whole-body dose by factors of up to 25. Since the estimation of cumulated activity in bladder contents is necessary for bladder dosimetry, a nomogram based on a 3.5 h voiding period is presented as a convenient aid for this purpose.

Bone Marrow↗
PubMed1980

Increased alveolar epithelial permeability in cigarette smokers.

Two indices of alveolar epithelial permeability were derived in man by a non-invasive method. The rate of transfer of 99mTc DTPA (diethylenetriamine penta-acetate) from the lung into the blood was measured and a significantly greater (P less than 0.001) transfer rate was found in symptomless cigarette smokers compared with non-smokers.

Adult↗
PubMed1980

The reproducibility of double-isotope deconvolution measurements of intestinal calcium absorption.

1. Radiocalcium absorption was measured in duplicate in 10 subjects by the double-isotope method, with calcium as the oral carrier (2.5 mmol). Analysis of variance gave 95% confidence limits for a single measurement of fractional absorption and maximum absorption rate in a given individual of +/- 16.5% of administered dose and +/- 18.2% of dose/h respectively. 2. The size of these within individual variations suggests that alterations in the rate of calcium absorption may contribute to the week-to-week stabilization of some other controlled variable, such as plasma concentration of calcium. 3. In six of the subjects, calcium absorption was also measured with calcium loads at concentrations of 0.5, 5.0 and 20 mmol. Significant falls in fractional absorption, maximum absorption rate and mean transfer rate occurred as the load increased, together with a rise in mean transit time. Although between-individual differences at a given load were considerable, given a single-test result with a known carrier load, it is possible to predict quite accurately the results which would be obtained if a different carrier load were to be given.

Analysis of Variance↗
PubMed1980

Methods and problems in the measurement of body water and electrolyte pools with radionuclide tracers.

With the possible exception of ECF, body electrolyte spaces and pools can be measured with fair accuracy and are useful in their proper experimental context. The use of improved tracer techniques and mathematical analysis to study transfer rates between pools and the physiological factors which influence these rates offer a promising means of further progress in this field.

Body Fluid Compartments↗
PubMed1977

The relative transfer rates for sodium and xenon from gut lumen to plasma in man.

1. A whole-gut perfusion technique has been used to compare the rates of intestinal absorption of sodium and xenon. 2. The calculated transit-time spectra for sodium and xenon across the gut mucosa do not differ significantly either in mean transit time or, for the first 15 min, in shape. 3. These results support the hypothesis that the rate of transfer of sodium from the small intestinal lumen to plasma is limited by blood flow. 4. It is suggested that some features of cholera can be explained by the hypothesis.

Humans↗