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Biomedical subjects

K Rootwelt

Publications and source records attributed to K Rootwelt.

At least 73 records · Page 4Linked to original sources
PubMed1986

Measurement of cerebral blood flow with 133Xe inhalation and dynamic single photon emission computer tomography. Normal values.

Cerebral blood flow (CBF) was studied by 133Xe inhalation tomography in 25 healthy subjects. Mean age was 41 years and range 23-66 years. Mean hemispheric CBF at rest was 59.8 ml/100 g/min, and cerebellar flow 60.8 ml/100 g/min. This difference was not statistically significant. The distribution of CBF values was skewed and approximated a log normal distribution. Estimated lower and upper normal reference range limits calculated as mean (log) +/- 2 S.D. (log) were 47-74 ml/100 g/min. Women had approximately 5 ml/100 g/min higher CBF values than men. This difference corresponded to the difference in hematocrit. Neither in men nor in women was there any tendency to age dependent reduction or increase in flow. In both sexes hemispheric regional CBF (rCBF) was asymmetric with higher flow values in the right cerebral hemisphere; particularly in the anterior distribution territory of the middle cerebral artery. In this region the maximum individual flow difference was 8 ml/100 g/min and the average difference 3.5 +/- 2.6 ml/100 g/min. Emotional activation as a consequence of the study conditions is assumed to be the cause of this observed asymmetry. Cerebellar flow was not assymetric. No significant difference in cerebellar or hemispheric CBF was found when a second study followed the first by 3-15 months. PCO2 correction of flow improved the reproducibility. The standard deviation of the flow difference between test/retest measurements was 5 ml/100 g/min. After 1 g acetazolamide given intravenously the mean increase in hemispheric CBF was 15.7 +/- 5.1 ml/100 g/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetazolamide↗
PubMed1985

Significance of a positive exercise ECG in middle-aged and old athletes as judged by echocardiographic, radionuclide and follow-up findings.

To study the pathologic and prognostic significance of--and possible underlying mechanisms for--a pathological exercise ECG in athletes, two age-matched groups were selected from a total population of 117 middle-aged and old endurance athletes: Group A: 21 with a pathological exercise-ECG, and group B: 21 with normal exercise-ECGs. Data from 201-thallium perfusion scintigraphy, 99 m-technetium multiple gated acquisition ventriculography (MUGA), resting echocardiography and 3 years follow-up are as follows: None had thallium findings indicating reversible myocardial ischaemia, but one from group A had a probable old myocardial infarction. All had normal resting MUGA, but group A men slightly more often presented a subnormal increase in ejection fraction according to exercise MUGA than group B men (9/20 vs 4/21). The former also more often had ventricular hypertrophy (LVH) (19/21 vs 14/21). However, apart from slightly longer ventricular filling time among group A men the echocardiograms revealed no group differences e.g. in cardiac dimensions or in indices of systolic or diastolic function. Regardless of exercise-ECG response, 18/42 athletes had one or more value of left ventricular dimensions or diameter exceeding the 95th percentile of the normal range. Since one patient from group A had asymmetric septal hypertrophy, one developed cardiomyopathy during the 3 years follow-up and one had a previous myocardial infarction, only 3/21 had cardiac disease which might explain the pathological exercise-ECG. Thus, pathological exercise-ECG rarely signifies heart disease in athletes, and very rarely coronary heart disease. Rather, the pathological exercise-ECG may be related to LVH and various subtle alterations in cardiac physiology following long-term endurance training.

Adult↗
PubMed1985

Ferrochelatase deficiency in the bone marrow in a syndrome of congenital hypochromic microcytic anemia, hyperferremia, and iron overload of the liver.

Two sisters had congenital hypochromic microcytic anemia with hyperferremia, heavy iron deposits in the liver, and reduced bone marrow iron. Liver ferrochelatase activity was within normal limits, but in the bone marrow ferrochelatase activity was only 20% of that in healthy controls. There were no findings suggestive of lead intoxication, sideroblastic anemia, or erythropoietic protoporphyria.

Adult↗
PubMed1984

Measurement of intracranial blood volume by gamma camera emission tomography.

Based on phantom and animal experiments a method is proposed for measuring the intracranial blood volume ( ICBV ) by gamma camera emission tomography. The intracranial radioactivity from 99mTc -tagged erythrocytes in intracranial vessels is measured with a gamma camera rotating around the head of the dog with a circulatory turn of 2-20 min. The radioactive counts from each cycle are pictorially displayed as 8-12 frontal sections through the head. On each section the intracranial space is delineated as the region of interest and counted separately. The sum of the intracranial counts of the various sections is an expression of the ICBV and linearly related to it. Accurate delineation of the intracranial space on each of the displayed slices is achieved by injection of a nondiffusible isotope ( 169Yb -DTPA) into the subarachnoid space at the end of each experiment. Scattered radiation is corrected for by a correction factor obtained from the phantom experiments. By means of special calibration procedures the measured ICBV , as expressed in counts may be transferred into volume units (ml). The present method seems to offer several advantages compared to earlier methods for measuring the ICBV .

Animals↗
PubMed1983

Severe iron deficiency causing loss of ring sideroblasts.

A patient with primary sideroblastic anaemia was observed for more than 10 years with 50% ring sideroblasts in the bone marrow and a Hb of 84-109 g/l. Iron deficiency then developed with loss of stainable iron in marrow particles (reticuloendothelial iron) and loss of all ring sideroblasts. When iron tablets had brought the iron stores in the bone marrow up to subnormal levels, the Hb was over 110 g/l, somewhat higher than it had been when the iron stores were increased. The ring sideroblasts were again raised to more than 50%.

Anemia, Sideroblastic↗
PubMed1983

False suspicion of coronary heart disease: a 7 year follow-up study of 36 apparently healthy middle-aged men.

Latent coronary heart disease was suspected in 115 of 2014 apparently healthy middle-aged men after a baseline cardiovascular survey. One hundred five of these men underwent angiography and 36 were found to have normal coronary arteries (group 1). A 7 year follow-up survey revealed that: (1) three had died of sudden cardiac death, (2) four had received a diagnosis of cardiomyopathy, (3) one had developed aortic dilatation/aortic regurgitation since the baseline survey, (4) they all had a significantly more rapid decline in their physical performance and maximal heart rate levels from the time of the baseline survey to follow-up than did randomly selected normal controls (group 2), and (5) thallium study results were normal in both groups (27 and 26 patients), but technetium ventriculography revealed a subnormal increase in ejection fraction during exercise (less than 5% units) in 14 of 27 group 1 subjects and in 4 of 26 group 2 subjects. Thus, incipient heart disease may be present in subjects in whom coronary angiographic examination has removed a previous suspicion of coronary heart disease.

Adult↗
PubMed1982

Detection of coronary artery disease with gated cardiac blood-pool scintigraphy: comparison of cold pressor test and dynamic exercise.

Forty-six subjects (11 normals with no cardiac disease, 13 persons with a 'false' positive exercise ECG test, and 22 patients with coronary artery disease) were investigated with ECG-gated cardiac blood-pool imaging at rest, during cold pressor stimulation, and during supine bicycle exercise. Changes in left ventricular ejection fraction and intervention induced regional wall motion abnormalities were measured. Cold pressure stimulation did not induce anginal pain in any person, but were generally found more unpleasant than dynamic exercise. Dynamic exercise detected significantly more coronary artery disease patients (20/22, 91%) than did cold stimulation (13/22, 59%) (P less than 0.02). Specificity of dynamic exercise and cold stimulation was not significantly different. It is concluded that cold stimulation is less sensitive than dynamic exercise in the detection of patients with ischaemic heart disease with gated cardiac blood-pool imaging.

Cold Temperature↗
PubMed1982

Routine radionuclide techniques in evaluation of patients with suspected coronary heart disease.

Myocardial scintigraphy with thallium-201 and electrocardiogram-gated left ventriculography with technetium-99m labelled red blood cells were applied in four groups of subjects: 25 with no signs or symptoms of cardiovascular disease (group 1), 28 with a "false" positive exercise electrocardiogram (group 2), 14 with angina pectoris and normal coronary angiograms (group 3), and 43 with angina pectoris and fixed coronary artery stenoses (group 4). In groups 1 and 4 the radionuclide findings were in accordance with clinical and invasive measurements. In groups 2 and 3 the most important finding was the lack of increase in left ventricular ejection fraction during exercise in about half of these subjects (even a decrease in 25%), indicating subnormal myocardial reserve. The additional finding of pathological myocardial biopsies in four of these patients suggests that asymptomatic ST depression in patients with normal coronary angiograms may in some cases represent an early, preclinical sign of cardiomyopathy.

Angina Pectoris↗
PubMed1981

Pituitary fuction during X-ray treatment of the hypothalamic-pituitary region as evaluated by the TRH test response.

The effect of conventional radiotherapy on the TRH response was studied in fourteen patients, all but one previously surgically treated for pituitary tumors. No change in the TSH response to TRH could be observed either during or after a four week treatment period, thus demonstrating relative resistance of the pituitary gland against irradiation in these patients. We also conclude that the diagnostic value of the TRH test remains unhampered during and in the immediate period after irradiation.

Humans↗
PubMed1981

Free thyroxine, thyroxine/TBG ratio and other in vitro tests of thyroid function evaluated by discriminant analysis.

T4, T3, TSH, FT4 (Corning method), TBG, T3U and a diversity of free thyroid hormone indices were determined in serum from 72 reference persons and 337 patients with either thyroid diseases, TBG abnormalities, non-thyroid illnesses, or medications known to affect the results of thyroid function tests. Ninety-six per cent were 20 years or older. None of the laboratory parameters showed significant age or sex dependence, whereas systemic illness and medications frequently influenced test results. Thus the mean values of all patient groups differed significantly from those of the reference group in two or more laboratory tests, and significantly from those of the reference group in two or more laboratory tests, and significant differences were detected in 73% of the total number of 209 paired comparisons of test results between reference and patient groups. As a single parameter, free thyroxine index was found to be a marginally more efficient thyroid function discriminator than FT4, which again was more efficient than the T4/TBG ratio. However, non of these parameters were included in the combinations of laboratory tests identified as optimum by discriminant analysis. The overall optimum test combination was T4, TSH and T3U, which had an efficiency for correct thyroid function reclassification better than 98% in the total material. T3 replaced TSH in distinguishing between hyperthyroidism and euthyroidism.

Adolescent↗
PubMed1978

Optimum laboratory test combinations for thyroid function studies, selected by discriminant analysis.

In 430 patients with a variety of thyroid disorders, linear discriminant analysis was used to select laboratory test combinations giving optimum diagnostic efficiency in thyroid function studies. Unexpectedly, TSH was found valuable in the diagnosis of hyperthyroidism and T3 in hypothyroidism. These test combinations were found optimal for the separation of euthyroidism/hyperthyroidism: T3, TSH and T4; euthyroidism/hypothyroidism: Combined free thyroid hormone index (FTI) and TSH; and hyperthyroidism/euthyroidism/hypothyroidism: T3, TSH, T4, FTI and T3U. The latter test combination had a total efficiency of 94%. Cholesterol, achilles reflex time, PBI and radioiodine uptake measurement contributed little to the discrimination.

Adolescent↗