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Biomedical subjects

F S Keck

Publications and source records attributed to F S Keck.

46 records · Page 3Linked to original sources
PubMed1987

Radionuclide ventriculography and hemodynamic evaluation by right heart catheterization with exercise for assessing the functional significance of coronary artery stenoses. A comparative study.

A series of 13 patients with significant coronary stenoses but without prior myocardial infarction were simultaneously studied by right heart catheterization and radionuclide ventriculography to determine the extent to which abnormal responses in left ventricular ejection fraction and wall motion to maximum exercise are paralleled by abnormal left ventricular filling pressures. The correlations of the filling pressure as evaluated by the diastolic pulmonary artery pressure with both the exercise ejection fraction and the rest-to-exercise change in ejection fraction were high (r = -0.89, P less than 0.01 and r = -0.76, P less than 0.01, respectively). In addition, the filling-pressure response to stress separated the patients into distinct radionuclide categories. All the 7 patients with grossly abnormal filling pressures (P greater than or equal to 30 mmHg) developed regional wall motion abnormalities with exercise as evaluated by visual interpretation or quantitative phase analysis. These patients also had a decrease in ejection fraction from rest to exercise ranging from -9% to -32% together with an exercise ejection fraction below 50%. Conversely, these abnormalities were never found in patients with filling pressures below this threshold level. The data suggest that radionuclide ventriculography and measurement of left ventricular filling pressure with exercise yield corresponding results when assessing the functional significance of coronary stenoses in normotensive patients without prior myocardial infarction and normal global left ventricular function at rest.

Blood Pressure↗
PubMed1987

Thyroid hormones alter mRNA activity profiles of differentiated 3T3-L1-cells.

The influence of thyroid hormones on the gene expression of 3T3-L1-adipocytes was examined. mRNA activity profiles were investigated by in vitro-translation and 2D-electrophoresis. Seven protein spots out of 210 were sensitive to 3,5,3'-triiodothyronine (T3). All proteins increased from hypothyroid to hyperthyroid status. Additionally two spots increased from hypothyroid to T3-substituted and euthyroid status. There is evidence for the existence of protein S14 in differentiated 3T3-L1-cells, as part of spot 5.

Adipose Tissue↗
PubMed1986

[Acute factitious hyperthyroidism--moderate clinical symptoms in 3 cases under beta-blocker treatment].

The clinical and laboratory findings are described in three patients who ingested large amounts of L-thyroxine (two cases) and L-thyroxine together with L-triiodothyronine and who were treated with propranolol. Serum concentrations of thyroxine (maximum values 75 micrograms/dl, 64 micrograms/dl, and 20 micrograms/dl, respectively; normal range 4-12 micrograms/dl), triiodothyronine (maximum values 837 ng/dl, 453 ng/dl, and 566 ng/dl, resp.; normal range 80-180 ng/dl), reverse triiodothyronine (maximum values 235 ng/dl, 190 ng/dl, and 65 ng/dl, resp.; normal range 10-40 ng/dl) as well as free thyroxine equivalent and free triiodothyronine equivalent were monitored daily until they reached the normal range. Statistical analysis of the kinetics of these parameters indicated that the extreme thyroxine conversion was directed toward reverse triiodothyronine, partly due to the treatment with the beta-adrenergic blocker propranolol. The striking discrepancy between the high concentrations of the active hormones and the moderate clinical symptoms was most likely caused by peripheral effects of propranolol.

Adolescent↗
PubMed1984

Increased hepatic microsomal T3 production in vitro induced by insulin administration in rats in vivo.

Rats were treated with insulin infusion over 12 h with or without addition of cycloheximide and compared with controls. T4 to T3 deiodination in microsomal liver fraction was measured. Insulin treatment led to an increase in T3 production, whereas this effect was blunted by the inhibition of protein synthesis by cycloheximide. Neither serum concentrations of T4 nor the liver content of non-protein-bound sulph-hydryl groups explained the alterations in T3 production. It is strongly suggested that insulin directly acts on T4-5'-monodeiodination by stimulating de novo synthesis of protein.

Animals↗
PubMed1984

T3-hyperthyroidism caused by enhanced and shifted T4-conversion.

Radioactivities of endogenously labelled thyroid hormones following in vivo application of 131 I and extraction from serial blood samples, show that T4 secretion is enhanced in T3-hyperthyroidism as it is in T4-T3-hyperthyroidism. In an extreme case of T3-hyperthyroidism with serum concentrations (SC) of T3 nearly equal to T4 (1000 ng/dl and 1800 ng/dl, respectively) tracer studies revealed a very short half life of T4 when compared to T3 (21.8 and 20.2 hrs., respectively). In 110 cases with both types of hyperthyroidism, regression analysis showed that T3/T4 ratio as an indicator of T4 conversion, as well as T3/rT3 ratio as an indicator of the direction of the conversion, are related to T4SC (r = -0.84 and -0.72, respectively, p less than 0.001). T3-hyperthyroidism is described by high values of these ratios. For the definition of T3-hyperthyroidism it is suggested that both T4 and rT3SC are within the normal range (T4 less than or equal to 11.5 micrograms/dl, rT3 less than or equal to 43.0 ng/dl) and according to this definition, T3/rT3 is higher than in T4-T3-hyperthyroidism and in an undefined group (24.8 +/- 4.5 vs. 6.3 +/- 0.4 or 7.5 +/- 0.4, respectively). By means of the ratios the undefined group may be allocated to T4-T3-hyperthyroidism. The T3/rT3 ratio is value of greater than 10 has a frequency of 88% in thus defined T3-hyperthyroidism and a ratio of less than or equal to 10 is found in 90% of the other cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Granulocytes↗
PubMed1982

Detection of temperature increases in the operating range of warm receptors and of nociceptors.

In healthy subjects the ability to detect small temperature increases in a 'two-alternative forced choice' experiment was tested from different basic temperatures ranging between 36 and 46 degrees C. Detection improved up to an adapting temperature (AT) of 40 degrees C, a further increase of AT into the operating range of nociceptors did not change detection rate. In several experiments the subjects have been asked to rate their confidence after each forced choice on a 6-point scale. From these confidence ratings two measures developed in the context of 'Sensory Decision Theory' have been calculated, one of 'discrimination' and one of 'bias.' A bias towards higher confidence in having detected temperature increases was found to be the clearest sign of transition into the operating range of nociceptors.

Hot Temperature↗
PubMed1980

[Reliability of perfusion manometry in the gastro-esophageal closure mechanism (author's transl)].

Manometric investigation of the gastro-esophageal closure mechanism is an important tool for the classification and adequate therapy of functional disorders in this region. Because of the relatively low pressure differences the reliability of a measuring procedure has to meet all requirements. Manometry by continuously perfused and withdrawn catheters being the most frequently applied measuring procedure got some criticism regarding its reliability and reproducibility. The theoretical basis of this criticism is examined closely. The reproducibility of the recorded pressure curves is studied and quantified in 36 dogs and 122 persons (32 controls, 63 patients with hiatal hernia, 27 patients with achalasia of the cardia). On experimental condition, lower esophagel sphincter pressure shows a high degree of reproducibility (retest reliability r = .98, p less than 0.001), in clinical investigations it is significantly lower (r = .81). There are no statistically significant differences between the patient groups and the controls. The importance of the findings for the reliability and the interpretation of clinical manometric data is discussed.

Animals↗
PubMedDate not supplied

The first experimental diabetes mellitus.

In the history of diabetes research, surgically induced experimental diabetes is usually associated with the names of Minkowski and von Mering on the basis of their investigations in 1889. However, temporary diabetes mellitus had already been induced 200 years previously by Johann Conrad Brunner (1653-1727) in an experiment in dogs. According to present-day knowledge, this temporary diabetes mellitus must be ascribed to subtotal pancreatectomy and reversible traumatic damage to the remaining endocrine pancreas. The brilliant experimenter Brunner did not associate the symptoms he produced with diabetes. Diabetes research would possibly have taken a different course had he done so.

Animals↗