Biomedical subjects
Publications and source records attributed to M H Jonckheer.
Clinical, scintigraphic and laboratory findings in a group of 23 hyperthyroid patients with inappropriate total intrathyroidal iodine pool (ITI), measured by X-ray fluorescence, were compared to those of 25 hyperthyroid patients with low ITI. Differences are discussed which may be useful in the diagnosis of this clinical entity.
In 136 normal growing children between the ages of 1 and 18 yr, bone mineral content (BMC) at the level of the lumbar spine (L2-L4) was determined with a commercial dual-photon absorptiometer. BMC was calculated as BML (BMC per unit length) and BMD (BMC per unit surface). The mean lumbar spine BML of the studied children (2.53 +/- 0.86 gHA/cm) was significantly lower than the spinal mineral content of adults (4.26 +/- 0.57 gHA/cm). No sex difference existed in lumbar spine BMC. BML as well as BMD were highly dependent on age, body height, and body weight. During the prepubertal years, BML and BMD increased in a fairly rectilinear pattern. During puberty, BMC increased more rapidly: 40% for BMD and 77% for BML. For the entire group, the increase in BMC with age, height, and weight was best predicted by an exponential regression line analysis.
In recent years, *I-MIBG (*I-metaiodobenzylguanidine), which is transported and stored in the chromaffin cells, has been shown to allow good visualization of neuroblastomas in children. This paper deals with 30 *I-MIBG-scans performed in 20 children: 16 with neuroblastoma, 3 with retinoblastoma, and 1 with a malignant paraganglioma. A high detection rate was found for both primary and secondary sites of neuroblastoma. *I-MIBG was generally superior to 99mTc-MDP bone scintigraphy in the detection of bone metastases. Our experience illustrates the unique place of *I-MIBG-scintigraphy compared with other imaging techniques: it makes it possible to define the nature of the tumour, particularly in cases with normal catecholamine levels; to establish how extensive the lesions are at the time of diagnosis; and to confirm complete remission. No abnormal *I-MIBG uptake was noted in the 3 cases of retinoblastoma.
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Since the early eighties, *I-MIBG (= *I-metaiodobenzylguanidine), which is stored in the neurotransmitter storage granules of chromaffin cells, has been increasingly used for the detection of pheochromocytomas and allied sympathoadrenal pathologies. The aim of this paper is to illustrate, by means of clinical examples, the role of *I-MIBG-scintigraphy in child neuroblastoma and to underline its original place, compared with other imaging techniques, in determining the neuro-ectodermal origin of a tumor as well as in establishing the extension of the lesions at the time of diagnosis and during follow-up.
Bone mineral content (BMC) was measured at the lumbar spine region by means of dual photon absorptiometry over a 3-year period in 20 patients on regular hemodialysis (RHD). Baseline mean BMC at the start of the monitoring was significantly decreased to 82.64% of predicted value (p less than 0.05). During a 3-year follow-up mean BMC rose significantly to 90.61% (p less than 0.05). Six patients received vitamin D supplements. Analysis of the data showed that rise of BMC was similar whether vitamin D was given or not. Our data suggest that (1) RHD inhibits bone loss at the lumbar spine level that occurred mainly before active uremia treatment and (2) the increment of BMC observed in this study can be attributed to the different site of measurement, the inaccuracy of the measurements by interference with soft tissue calcifications and the dialysis conditions.
Hemodynamics were evaluated in 8 patients with uncomplicated renal failure on regular dialysis before and after partial correction of anemia by treatment with recombinant human erythropoietin (r-huEPO). Under r-huEPO treatment, mean (+/- SD) hemoglobin increased from 7.51 (0.60) to 10.27 (0.92) g/dl. Mean blood pressure, body weight, total blood volume and extracellular fluid compartment remained unchanged. Cardiac output as measured with a radionuclide method increased significantly from 4622 (1069) to 5393 (1285) units (p less than 0.02) and peripheral resistance decreased from 22 (4) to 19 (3) units (p less than 0.02). 6-keto-1-alpha-prostaglandin decreased from 96.9 (54.4) to 61.6 (18.0) pg/ml (p less than 0.05) but plasma renin activity, noradrenalin and atrial natriuretic peptide remained unchanged comparing pre- and post-treatment levels. This observation suggests that an increase of red blood cell mass can improve heart function in patients undergoing regular dialysis treatment.
To assess the value of antithyroid drugs as an adjunct to radioactive iodine for the treatment of hyperthyroidism the incidence of relapse or hypothyroidism after a mean follow-up of 5 1/2 years (range 2-7 years) was reviewed retrospectively for 206 patients, some treated with and others without antithyroid drugs after radioiodine therapy. Allocation to treatment group had been random, and both groups were similar in all respects except for the adjunctive treatment with antithyroid drugs. All doses of 131I had been calculated by one physician. Compared with those who received 131I alone, those starting on antithyroid drugs within 8 days after 131I had a lower incidence of hypothyroidism but a higher incidence of early post-treatment recurrence or persistence of hyperthyroidism, and a considerably lower incidence of remission.
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The effect of the converting enzyme inhibitor lisinopril on renal and cardiac hemodynamics was studied in patients with moderate to severe primary hypertension, in a multicenter, double-blind, randomized clinical trial comparing the antihypertensive effect of lisinopril (LIS) and nifedipine (NIF). After a 2 week placebo run-in period, 15 patients were randomized in a 2:1 ratio to receive either LIS (20-80 mg q.d., n = 10) or NIF (20-40 mg b.i.d., n = 5). LIS significantly reduced blood pressure (BP) without changing heart rate or cardiac output. LIS significantly increased renal blood flow; glomerular filtration rate (GFR) was not changed. It can be concluded that LIS is an effective antihypertensive agent with a favorable renal hemodynamic profile.
A randomized, double-blind, placebo-controlled study was set up to study the effects of acute and chronic administration of carvedilol, a vasodilatory beta-blocker in essential hypertension. Acute administration of a single dose of 50 mg of carvedilol reduced systolic and diastolic blood pressure, without inducing reflex tachycardia. Renal blood flow was preserved; accordingly renal vascular resistance was significantly reduced. A significant reduction of glomerular filtration rate and filtration fraction was observed. Plasma renin activity (PRA) and plasma aldosterone were not changed. Chronic carvedilol treatment produced a significant fall in systolic and diastolic office and ambulatory blood pressure, heart rate, cardiac output, PRA and plasma aldosterone. Blood pressure variability was not changed. Renal blood flow, glomerular filtration rate and filtration fraction also remained unchanged; renal vascular resistance decreased significantly. It is concluded that carvedilol possesses definite antihypertensive and renal vasodilating properties, both acutely and after chronic treatment.
Chronic administration of nadolol has been reported to reduce blood pressure either without or with a concomitant fall of renal blood flow. We therefore studied the effects of nadolol 80 mg once daily on ambulatory blood pressure, renal and systemic haemodynamics in patients with mild to moderate essential hypertension. Ten patients took part in this randomized, double-blind, placebo-controlled, crossover study, each phase of which lasted 4 weeks. Nadolol significantly reduced ambulatory blood pressure and heart rate, but had no effect on blood pressure variability. Cardiac output was significantly reduced by nadolol and total peripheral resistance increased but without reaching statistical significance. Despite the fall in blood pressure and cardiac output, renal blood flow and glomerular filtration rate remained unchanged. The fraction of cardiac output reaching the kidneys rose significantly and renal vascular resistance was significantly reduced. Body weight, urinary sodium excretion and urine flow rate remained unchanged. We conclude that nadolol 80 mg once daily lowers ambulatory blood pressure in patients with mild to moderate hypertension without impairment of renal blood flow, indicating a redistribution of cardiac output to the kidneys. The mechanism of the renal vasodilator effect of nadolol remains to be determined.
Abnormally increased uptake of 99mTc-methylene diphosphonate in the kidney parenchyma was found in a patient with acutely exacerbated sarcoidosis. The findings could be related to active sites of nephrocalcinosis.
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A new method for the detection of deep-vein thrombosis is presented, consisting of a single antecubital injection of fibrinogen labeled with 99mTc. This atraumatic procedure allows one to visualize the large veins of the lower limbs, the venae iliacae and the distal part of the vena cava inferior. This paper discusses how to interpret these phlebograms.
Cardiac patients treated with the iodine-containing drug 'amiodarone' undergo a significant iodine overload which can last for months after the drug has been withdrawn. Some patients develop hyperthyroidism and others hypothyroidism. In the hyper- or hypothyroid patients, the indices of thyroid function are modified as usually observed in these situations. In the patients remaining euthyroid while taking amiodarone or after its withdrawal, but still under its influence as shown by the iodine overload, a 'low-T3 syndrome' is observed, this state being characterized by a high total T4, a low free T4, a normal T3 resin uptake, a low total T3, a normal free T3, a high r-T3 and a relative TSH-unresponsiveness to TRH.
Amiodarone induces in patients "low T3-syndrome" characterized by normal T4. T3 resin uptake and free T3, contrasting with low T3 and free T4 values, and enhanced concentration of r-T3.
Amiodarone is a drug which is frequently used in cardiology, and which can lead to the appearance of hyper- of hypo-thyroidism in certain cases. A study of the various parameters of thyroid function has shown that these are abnormal in every case treated by this drug, without the biochemical abnormalities necessarily being reflected clinically. The authors outline a method which will allow a distinction to be drawn between patients with a true thyroid malfunction and those whose biochemical results do not appear at first sight to be of any consequence. Regular assays of the T3RIA level are suggested as a means of early detection of thyroid malfunction in patients undergoing treatment with amiodarone.