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Biomedical subjects

M de Roo

Publications and source records attributed to M de Roo.

15 recordsLinked to original sources
PubMed1992

Evaluation of 99mTc-mercaptoacetyltripeptides in mice and a baboon.

Different derivatives of MAG, carrying amino acids such as D- or L-alanine, D-serine, D-2-aminobutyric acid, D-valine or D-phenylglycine were synthesized and their 99mTc-complexes were evaluated in mice and a baboon. The efficiency of renal handling of the examined 99mTc-complexes is influenced not only by their lipophilicity but also to a great extent by their configuration and the site of substitution. The renal excretion characteristics of 99mTc-MAGAG-DA are superior to those of 99mTc-MAG3 and the studied 99mTc-complexes in both animal species. In an attempt to improve the renal handling of 99mTc-MAG3 and to evaluate the effect of derivatization we have synthesized different derivatives of MAG3 in which one or more glycyl groups are replaced by other amino acids such as D- or L-alanine, D-serine, D-2-aminobutyric acid, D-valine or D-phenylglycine. Due to the presence of a chiral centre in the ligand core, exchange labelling of each of the MAG3 derivatives results in the formation of two diastereomeric technetium complexes. These isomers were separated by HPLC and evaluated in mice. Biodistribution in mice indicates that the efficiency of renal handling of the examined 99mTc-complexes is not only influenced by their lipophilicity but also to a great extent by their configuration. The renal excretion characteristics of isomer DA of 99mTc-MAGAG in mice are superior to those of all other studied 99mTc-complexes and also of the reference compound [131I]Hippuran. The isomers LB of several alanyl derivatives of 99mTc-MAG3 exhibit a pronounced renal retention in both mice and baboon. The results of the evaluation in a baboon confirm the superiority of 99mTc-MAGAG-DA over 99mTc-MAG3 and the other studied 99mTc-complexes.

Amino Acid Sequence↗
PubMed1992

Computed cranial tomography, magnetic resonance imaging and single photon emission computed tomography in hemorrhagic shock and encephalopathy syndrome: a report of three cases.

Three different neuro-imaging studies were performed in 3 infants with hemorrhagic shock and encephalopathy syndrome (HSE). Areas of cerebral infarction were noted on CT. Single photon emission computed tomography (SPECT) showed decreased perfusion in these areas in one infant. Magnetic resonance imaging (MRI) also identified the areas of infarction, noted on CT, but provided additional information showing non-haem iron deposition in the thalami and basal ganglia.

Brain↗
PubMed1991

Left ventricular function changes during pharmacological and physiological interventions and routine activities monitored in healthy volunteers by a portable radionuclide probe (VEST).

A miniaturized radionuclide cardiac probe incorporated in a semi-rigid plastic chest garment has made ambulatory left ventricular (LV) function evaluation possible, with gated nuclear data being stored on tape together with electrocardiographic data, for subsequent off-line processing. After red blood cell labelling with 555 MBq (15 mCi) 99mTc and standard gated blood pool imaging in 45 degrees LAO, we performed a continuous monitoring of LV function in 20 healthy male volunteers (age range: 22-25 years), in resting control conditions as well as during activities (standing, walking, climbing stairs) and after interventions (isosorbide dinitrate intake, Trendelenburg position, inflation of cuffs around the thighs). VEST-monitoring proved to be a reliable method that gave reproducible results: changes of ejection (EF) in basal conditions were lower than 5% in 95% of the patients. Changes in LV function caused by daily activities were easily demonstrated. While standing effected no significant EF changes, walking and climbing increased EF by 6.9% (p less than 0.05) and 21.2% (p less than 0.05) respectively. Changes in LV volumes caused by alterations in venous return were also demonstrated. Compared with baseline, Trendelenburg increased end-diastolic volume (EDV) by 2.9% while isosorbide dinitrate and inflation of cuffs decreased it by 5.7% and 2.2% respectively.

Adult↗
PubMed1990

Single photon emission computed tomography (SPECT) in seizure disorders in childhood.

In 38 children with partial seizures, the EEG, CT and NMR findings were compared to the results obtained with Tc99m HMPAO single photon emission computed tomography (SPECT) in order to determine whether SPECT is a useful adjunct to EEG, CT and NMR in this age group. In 3 out of 7 patients with a normal EEG, SPECT showed focal abnormalities. Nine patients whose EEGs did not show adequate lateralization had an abnormal SPECT which revealed a focus. In 14 out of 21 patients with a normal CT, SPECT showed focal changes in 13 patients and diffuse changes in the other one. In 7 out of 12 patients with a normal NMR, SPECT showed focal abnormalities. Although clinical history and a careful description of the seizures are the most valuable information in partial seizure disorders, SPECT imagining gives valuable additional information, which might target treatment. SPECT was superior to CT and NMR with respect to the depiction of some kind of abnormality.

Adolescent↗
PubMed1990

The role of high resolution ultrasound and MRI in the investigation of infants with macrocephaly.

External hydrocephalus was diagnosed using computed tomography in seven children presenting with macrocephaly. The value of different imaging techniques in distinguishing between subdural effusions and external hydrocephalus was investigated. High resolution ultrasonography combined with magnetic resonance imaging appeared to provide enough information to make a distinction between these two conditions. Radionuclide cisternography was still required to assess the flow pattern of the cerebrospinal fluid (CSF) which was important when placement of a lumboperitoneal shunt was considered.

Gestational Age↗
PubMed1989

Effect of solid-meal caloric content on gastric emptying kinetics of solids and liquids.

In this study, we have evaluated the effect of the caloric content of a physiological test meal on the gastric emptying kinetics of solids and liquids. 22 healthy male volunteers were studied in two groups matched for age. After an overnight fast, each volunteer underwent the same test procedure; in the first group (G I), 10 volunteers received a meal consisting of bread, 111In-DTPA water and 1 scrambled egg labeled with 99mTc-labelled sulphur colloid; in the second group (G II) 12 volunteers were given the same meal but with 2 labeled eggs in order to increase the caloric content of the solid phase meal. Simultaneous anterior and posterior images were recorded using a dual-headed gamma camera. Solid and liquid geometric mean data were analyzed to determine the lag phase, the emptying rate and the half-emptying time for both solids and liquids. Solid and liquid gastric half-emptying times were significantly prolonged in G II compared to G I volunteers. For the solid phased, the delay was accounted for by a longer lag phase and a decrease in the equilibrium emptying rate. The emptying rate of the liquid phase was significantly decreased in G II compared to G I. Within each group, no statistically significant difference was observed between solid and liquid emptying rates. We conclude that the caloric content of the solid portion of a meal not only alters the emptying of the solid phase but also affects the emptying of the liquid component of the meal.

Adult↗
PubMed1988

Evaluation of 111In labelled white blood cells by in vitro functional tests and electron microscopy. Comparison of three labelling methods.

We have studied the influence of granulocyte labelling with commercially available 111In-oxine, tropolone (trop) or home made 111In-Mercapto pyridine (Merc) prepared by the method of Thakur (1985) on the cell structure by electron microscopy and on the cell function by enzymatic tests, random migration, chemotaxis, phagocytosis and bactericidal activity. The granulocytes were labelled with 400 microCi 111In-oxine in saline or 111In-trop or Merc in plasma. The effect of the chelating agents with and without addition of the tracer was studied (n = 4) with varying concentrations: 5-10 micrograms/ml oxine, 10-160 micrograms/ml trop and 1-4 micrograms/ml Merc. Chemotaxis and random migration were not affected by 111In-trop and clearly suppressed by 111In-oxine and Merc; the other tests were normal. The cell structure was disturbed by Merc. The labelling efficiency was excellent with oxine (90%), acceptable with trop (30%-80%) and poor with Merc (10%-25%). Without 111In, chemotaxis and random migration were normal up to a concentration of 80 micrograms/ml trop, 8.5 micrograms/ml oxine and 1 microgram/ml Merc. With addition of 111In, chemotaxis and random migration were unaffected up to 80 micrograms/ml by trop and markedly suppressed by Merc and oxine. It is concluded that labelling with 111In-trop assures intact cells.

Granulocytes↗
PubMed1985

Clinical evaluation of 99mTc-DMSA renogram.

Two hundred-two 99mTc-DMSA renograms for urologic problems were evaluated. Some technical aspects of the examination and the value of the scintigraphic depth estimation are discussed. Pre- and postoperative uptake values in patients with renal surgery and sequential postoperative examinations are considered. The value of DMSA renograms in predicting recovery in obstructive uropathy and in deciding to opt for conservative therapy or nephrectomy is discussed.

Aged↗
PubMed1985

Ocular penetration of (125I)IVDU, a radiolabeled analogue of bromovinyldeoxyuridine.

Following topical application of (125)IVDU, the radiolabeled analogue of bromovinyldeoxyuridine ([E]-5-[2-bromovinyl]-2'-deoxyuridine), as 0.5% or 0.3% eyedrops, to rabbits, (125I)IVDU appeared in the anterior chamber fluid at drug levels well above the minimum concentration (0.01 microgram/mL) required for inhibition of herpes simplex virus type 1 replication. These findings are consistent with the efficacy of 0.5% bromovinyldeoxyuridine eyedrops in the topical treatment of herpes simplex uveitis.

Animals↗
PubMed1976

Xenon and nitrogen single-breath washout curves in patients with airway obstruction.

In patients with chronic obstructive lung disease, we determined single-breath N2 and 133 Xe washout curves, and regional distributions of volumes (Vr) and of 133Xe boluses inhaled at residual volume (VIRV). Patients suffering from emphysema with minimal airway obstruction demonstrated large closing volumes and apicobasal distribution gradients, apparently because of a steep pulmonary recoil pressure-volume curve. In one subject with basal small airway disease there was no vertical gradient in regional residual volume; closing volume was increased with the 133Xe technique but almost absent with the N2 technique. Patients with moderate-to-severe airway obstruction had upward-sloping alveolar plateaus without distinct phase IV, and small apicobasal differences in Vr and VIRV. The latter resulted probably from increased regional differences in time constants counteracting the influence of gravity. Finally, patients with severe airway obstruction and basal emphysema demonstrated a rising N2 but a descending 133Xe plateau; the gradient for VIRV was normal, and reversed for Vr. This pattern was attributed to nongravitational differences in time constants causing a first in-first out distribution.

Adolescent↗