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Biomedical subjects

F Keller

Publications and source records attributed to F Keller.

At least 361 records · Page 20Linked to original sources

Intramural hematoma of the small intestine presenting with major upper gastrointestinal hemorrhage. Case report and review of the literature.

We report a case of an anticoagulated patient presenting with a massive upper gastrointestinal hemorrhage, abdominal pain, and a palpable abdominal mass, demonstrated to be an intramural hematoma of the jejunum. Approximately two-thirds of intramural hematomas of the small intestine are preceded by abdominal trauma with the remainder associated with pancreatic disease, alcoholism, unknown causes, or clotting defects. Spontaneous occurrence of intramural hemorrhage is uncommon. Of the varied clinical presentations, gastrointestinal bleeding, previously thought unusual, is seen in 30% of cases, although major hemorrhage is rare. Conversely, reports of intramural hematoma of the small intestine as a case of major gastrointestinal bleeding has not been recognized. A review of the literature follows, and the authors stress that abdominal trauma should raise the possibility of an intramural hematoma of the small bowel.

Abdominal Injuries↗

The role of arteriography in abdominal aortic aneurysm.

The results of arteriography in the management of 100 consecutive patients with abdominal aortic aneurysms are presented. Arteriographic information had substantial influence upon management decisions and performance of surgery in 75 per cent of cases. We found the preoperative knowledge of the precise vascular pathology or anatomic variants not only permitted a more rational recommendation for or against surgery but aided in the selection of the most suitable surgical procedure.

Aged↗

Overall pharmacokinetics during prolonged treatment of healthy volunteers with digoxin and beta-methyldigoxin.

Five healthy volunteers received digoxin 0.4 mg or beta-methyldigoxin 0.4 mg i.v., daily for 14 days, in a randomized cross-over arrangement. By monitoring minimal plasma concentrations during multiple dosing, it was found that the steady state pharmacokinetics of digoxin and beta-methyldigoxin could be estimated even better by a one-compartment than by a two-compartment model. The following mean parameters were calculated: the half life of digoxin of 1.54 +/- 0.31 days was significantly shorter than the half life of 2.29 +/- 0.34 days for beta-methyldigoxin. The distribution volume of 807 +/- 187 liters for digoxin was not significantly larger than the 735 +/- 227 liters for beta-methyldigoxin. Renal digoxin clearance of 191 +/- 25 ml/min was significantly higher than both the renal clearance of beta-methyldigoxin of 111 +/- 23 ml/min and also the creatinine clearance, which indicates tubular secretion of digoxin. There was a 2.8-fold accumulation of beta-methyldigoxin injected once a day, which was significantly higher than the 1.80-fold accumulation of digoxin.

Adult↗

[Biologic availability and "1st pass" effect of drugs].

Bioavailability and "first pass"-effect are of increasing importance in Clinical Pharmacology. Bioavailability is the rate and above all the extent to which a drug reaches the systemic circulation. Reduced bioavailability may result from the physico-chemical properties of the drug, its solubility in the intestinal tract and its ability to permeate the gut wall. Reduced bioavailability may also result from a "first pass"-effect if the drug is metabolized during absorption by the enteral mucosa or during its first liver passage. Some conclusions may be drawn which are of importance for the clinic and pharmacy from the presented empirical and theoretical examples.

Administration, Oral↗

Bioavailability of digoxin: some pitfalls and problems.

The bioavailability of tablet formulations averages about 60% for digoxin, 75% for beta-acetyldigoxin, and 75% for beta-methyldigoxin. Bioavailability as a measure of the absolute amount reaching the systemic circulation should be calculated from steady state data. Only in steady state does the retarding effect of absorption disappear which diminishes the p.o./i.v. relation of data. For a screening test bioavailability may be calculated from 24-hour renal excretion values after a single dose, performing absolute and relative studies consecutively in cross-over arrangements. The absorption rate constant of digoxin and its derivatives is approximately 0.7 (h-1) which corresponds to an absorption half life of about 1 hour. The absorption rate constant can be calculated from plasma concentration values as well as from renal excretion rates 1 or 2 hours after dosing.

Biological Availability↗

Effects of chronic anemia on the coronary and coronary collateral vasculature in dogs.

We compared coronary resistances and collateral (retrograde) flows for a group of normal dogs (hematocrit 40) to values for a group of dogs with severe chronic anemia (hematocrit 17). We used an isolated heart preparation in which the vessels were maximally dilated by dipyridamole. All data were compared for a hematocrit of 40. The results showed a significant decrease in coronary resistances with anemia; average resistances (+/-SE) of the anterior descending, circumflex, and right coronary arteries of the control dogs were 1.04 +/- 0.09,0.74 +/- 0.01, and 2.63 +/- 0.17 mm Hg/[(ml/min)/100 g], respectively, and 0.6 +/- 0.04,0.41 +/- 0.05,and 1.17 +/- 0.15 for the anemic dogs. Average coronary collateral flows increased in anemia but statistical significance could not be shown. We conclude that increased vascularity is a long-term regulatory mechanism in response to a hypoxic stimulus.

Anemia↗