Because arteriovenous fistulae are associated with a palpable thrill and an audible murmur, the vibrational activity of the blood vessel walls about experimental arteriovenous fistulae in rabbits was investigated using, for the first time, a high-resolution laser vibrometer. Frequencies of mural vibrations up to 2200 Hz were recorded at different sites about the fistulae. The relationship of this vibratory activity of blood vessel walls to physiological and pathological conditions warrants further investigation.

Animals↗

PubMedDate not supplied

Doppler energy: a new acquisition technique for the transthoracic detection of myocardial perfusion defects with the use of a venous contrast agent.

AIMS: This animal experiment was designed to study whether the new technique of Doppler energy imaging could display myocardial perfusion abnormalities with the use of a combination of transthoracic imaging and right atrial injection of a myocardial contrast agent. METHODS AND RESULTS: A series of 11 pigs were studied during (1) normal perfusion, (2) dipyridamole-induced coronary dilatation, and (3) during and after temporary occlusion of the left anterior descending or circumflex artery after a right atrial injection of 8 ml Levovist, 400 mg/ml. Short-axis views were obtained with the four following imaging modes: gray scale imaging (two-dimensional and M-mode), Doppler energy imaging (two-dimensional and M-mode). Visual inspection and off-line video densitometry (results expressed in arbitrary videointensity units 0 to 255) with digital background subtraction were performed. Doppler energy was significantly more sensitive in detecting the presence of contrast than gray scale imaging (background subtracted peak videointensity 32 +/- 17 versus 17 +/- 12, p < 0.001). Mean background-subtracted videointensity increased during dipyridamole-induced coronary hyperemia (40 +/- 14 versus 31 +/- 9, p < 0.003) using Doppler energy technique. Doppler energy imaging consistently detected absent perfusion (background subtracted videointensity -6 +/- 6) and immediate reperfusion (background subtracted peak videointensity 29 +/- 15, p < 0.001). CONCLUSIONS: With the use of a galactose-based contrast agent, Doppler energy data acquisition was superior to standard gray scale imaging in transthoracic evaluation of regional myocardial perfusion, absence of perfusion, and reperfusion.

Animals↗

PubMedDate not supplied

[Reduced sympathetic sensitivity of the surviving heart muscle following experimental infarct].

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Animals↗

PubMedDate not supplied

[Pharmacological influences on fetal lung maturity, part V: Influencing the pulmonary DPL (dipalmitoyl lecithin) level with L-thyroxin (T4)].

Dipalmitoyl lecithin (DPL = DPPC, dipalmitoyl phosphatidyl choline) is both quantitatively and functionally the most important constituent of the surfactant complex. The effect of thyroxin (T4) on fetal lung maturity was investigated by means of selective DPL determination. Following administration of thyroxin to the mother animal an increase in the DPPC content was demonstrated in rat fetuses. This increase was greater than that of the total phospholipids. This effect of thyroxin could be due to the following causes: 1, Earlier and accelerated differentiation of lung cells: more Type II cells are formed earlier and these synthesize DPPC more effectively than other lung cells (approx. 40-50% of the phosphocoline in Type II cells in DPPC). 2. Stimulation of the deacylation-reacylation cycle. 3. A combination of these mechanisms.

Amniotic Fluid↗

PubMedDate not supplied

Acute liver failure due to temporary hepatic ischemia in the pig.

The model of temporary complete liver ischemia was investigated in 60 pigs in order to produce a disease which resembles liver failure in man. The interval of time leading to death in every animal differed in a wide range. A number of biochemical alterations was of no value as for the prognosis of the animal under investigation. The ammonium in the peripheral blood is elevated during shunting of portal blood around the liver only. Microscopic examinations demonstrated that the damage produced is limited to the hepatic tissue. The lesions were less when ischemia was produced after a longer interval after the operation. The role of processes of regeneration and reparation of liver tissue is discussed.

Animals↗