[Lateral ligament injuries]. / Außenbandverletzungen.

Due to the frequency and potentially complicated course distortion of the upper angle joint represents an important entity in the orthopedic patient clientele. The initial diagnosis includes a detailed anamnesis of the injury mechanism and an accurate clinical examination. To exclude bony, ligamentous and chondral lesions, besides basic diagnostics consisting of X­rays and ultrasound, magnetic resonance imaging (MRI) is considered the most important tool. Lateral ankle ligament injuries are generally treated conservatively. After a short period consisting of immobilization of the affected ankle, early functional therapy with semi-rigid orthoses and proprioceptive exercises should be performed. If conservative therapy fails and thus chronic instability develops the indications for operative treatment are given. Meanwhile, surgical techniques have been established with satisfactory results. Inadequate rehabilitation could be identified as a major risk factor for re-injury, therefore phase-adapted aftercare has gained significant importance.

Acute and chronic effects of a diuretic monotherapy with piretanide in congestive heart failure--a placebo-controlled trial.

To evaluate the acute and chronic effects of diuretic monotherapy with 3 mg piretanide bid, 46 patients (pts) with congestive heart failure (NYHA II-III) secondary to coronary artery disease were studied. Within 3 weeks of therapy, the patients lost 1.6 kg body weight. Forty-four patients reported a subjective feeling of improvement. Echocardiographically, a highly significant (p less than 0.001) reduction of diastolic and systolic diameters was found, as well as an increase of fraction shortening. Chest x-ray indicated a reduction of heart volume from 1012 +/- 263 ml to 936 +/- 233 ml (p less than 0.001). The serum potassium level remained unchanged. A subgroup of 26 pts underwent invasive hemodynamic examinations. IV injection of 6 mg piretanide resulted in an acute reduction of pulmonary wedge pressure (pc) from 20.2 +/- 5.3 mmHg to 11.9 +/- 5.0 mmHg (p less than 0.001); simultaneously a slight decrease of cardiac index from 3.2 +/- 0.6 l/min/m2 to 3.0 +/- 0.4 l/min/m2 was observed. Invasive control after 3 weeks of oral therapy showed no decline of the piretanide effect. The exercise tolerance increased clearly from 135 +/- 161 Wmin to 249 +/- 268 Wmin (p less than 0.05). A control group of further 14 pts was treated with placebo only and did not show any significant changes of pc (20.0 +/- 6.4 mmHg vs. 22.8 +/- 19.2 mmHg), exercise tolerance, or other clinical parameters. Thus, the diuretic monotherapy of congestive heart failure with piretanide is highly effective and shows a significant improvement in all clinical and hemodynamic parameters in the absence of any remarkable side effects.

High-affinity binding of ethacrynic acid is mediated by the two most important drug binding sites of human serum albumin.

The binding of ethacrynic acid to human serum albumin was investigated by means of circular dichroism and equilibrium dialysis measurements, using native human serum albumin and albumin derivatives with chemical modifications impairing specifically drug binding to the indole and benzodiazepine binding site or the azapropazone-warfarin binding area, respectively. The data presented indicate that the high-affinity binding of ethacrynic acid to human serum albumin is mediated by these two important drug binding sites. Accordingly, even at relatively low concentrations ethacrynic acid displaces other drugs from both binding sites.

Intracellular sodium and calcium during antihypertensive treatment.

In 49 untreated essential hypertensives the effects of the loop diuretic, piretanide, in a dose of 12 mg daily (n = 14) and of 6 mg daily (n = 18) as well as of beta blockers (pindolol, metipranolol, atenolol, n = 17) on blood pressure, intracellular Ca++ and Na+ activity in red blood cells were examined. Intracellular ion activities were measured by ion-selective electrodes. The higher dose of piretanide caused a decrease of intracellular Ca++ activity and an increase of intracellular Na+ activity. Under the lower dose of piretanide there was a comparable decrease of intracellular Ca++ activity but no significant change of intracellular Na+ activity. Beta blockers decreased intracellular Ca++ activity but left intracellular Na+ activity unchanged. It is concluded that intracellular free Ca++ plays an important role in the regulation of vascular tone in essential hypertension. There seems to be no direct relation between intracellular free Na+ and blood pressure under antihypertensive therapy.

Intracellular electrolytes during antihypertensive treatment with a loop diuretic.

The effect of the loop diuretic, piretanide (12 mg/day on blood pressure and intracellular electrolyte composition in red blood cells during a six-week treatment period was studied in 14 previously untreated essential hypertensive patients. Blood pressure fell continuously during the six weeks, intracellular Na+ activity in red blood cells increased slightly (P less than 0.05), and there was a marked decrease in intracellular Ca2+ activity (P less than 0.01). Intracellular K+ concentration was not altered. It is concluded therefore, that intracellular free Na+ does not correlate with the actual blood pressure, whereas the fall in blood pressure is associated with a decrease in intracellular free Ca2+, suggesting that intracellular free Ca2+ is involved in the regulation of vascular tone.

Beta-carboline binding indicates the presence of benzodiazepine receptor subclasses in the bovine central nervous system.

Receptor binding studies were performed with tritiated propyl beta-carboline-3-carboxylate ( [3H]PrCC), tritiated ethyl beta-carboline-3-carboxylate ( [3H]ECC), and tritiated flunitrazepam ( [3H]FNT) in membrane preparations from different regions of the bovine brain and retina. Specific binding in all regions investigated was associated with benzodiazepine receptor sites. However, not all benzodiazepine receptors in the regions investigated as determined by the specific binding of tritiated flunitrazepam ( [3H]FNT) are available for [3H]PrCC suggesting that specific [3H]PrCC binding labels only one subclass or subpopulation of the benzodiazepine receptor. This benzodiazepine receptor subclass is sensitive to GABAergic modulation and amounts for about 60% of the benzodiazepine receptors in bovine cortex, hippocampus, and retina but for about 80% of the benzodiazepine receptors in the bovine cerebellum. By contrast, specific [3H]ECC binding in the cerebellum and the hippocampus labeled the same number of benzodiazepine receptors as [3H]FNT, giving no evidence for a benzodiazepine receptor subclass specificity of this compound in the bovine CNS.

beta-Carboline inhibition of benzodiazepine receptor binding in vivo.

The in vivo potencies of 4 beta-carboline derivatives as inhibitors of benzodiazepine receptor binding were investigated. For all 4 derivatives maximal inhibition was seen within 2 min after i.v. application but decreased continuously for the next 20 min and after this time accounted for less than one-third of maximal inhibition. The in vivo potencies of the beta-carbolines as inhibitors of benzodiazepine receptor binding are much smaller than one would expect from their affinities measured in vitro. Thus, it is assumed than only a small portion of the i.v. dose reaches the brain.

Characterization of an important drug binding area on human serum albumin including the high-affinity binding sites of warfarin and azapropazone.

This paper reports a variety of experimental observations which strongly support the assumption that the warfarin binding site, or site I of human serum albumin, is better described as the warfarin-azapropazone binding area, consisting of the overlapping binding sites for warfarin and azapropazone. In general, drugs interacting with one of the two sites will also displace drugs bound to the other site, although their displacing potencies for both sites may vary considerably. This is most pronounced in the case of glibenclamide, which strongly inhibits the binding of drugs to the azapropazone site with only minor effects on drugs bound to the warfarin site. The lone tryptophan residue of human serum albumin, previously shown to be part of the warfarin binding site, is obviously located in the not-overlapping part of the warfarin site, so that its modification affects only the binding of drugs to the warfarin and not to the azapropazone site of this large binding area. The observation of different but overlapping binding sites might explain the fact that the albumin binding of drugs which seem to be bound to similar sites because of their mutual displacement can be affected differently during several disease states.

Optical studies on interaction of biliary contrast agents with native and modified human serum albumin.

The interaction of two homologous series of biliary contrast agents with native human and bovine serum albumin and with modified human serum albumin was investigated using circular dichroism and equilibrium dialysis. For most derivatives, extrinsic Cotton effects were observed for the interaction with both albumins. In some cases, these effects were strongly affected by only small changes in the chemical structure of the drugs. These large differences in extrinsic Cotton effects can be explained by definite effects of the chemical structures on the binding site selectivity of some drugs. For example, iopodate preferentially binds to the warfarin binding site of human serum albumin, while an ethyl group into the propionic acid side chain reduces the affinity for the warfarin site but strongly increases the affinity for the diazepam binding site of human albumin.

Benzodiazepine antagonism by harmane and other beta-carbolines in vitro and in vivo.

Harmane and other related beta-carbolines are putative endogenous ligands of the benzodiazepine receptor. Since the compounds are potent convulsants they may have agonist activities at the benzodiazepine receptor while the benzodiazepines may be antagonists. This hypothesis was proved by comparing the in vivo and in vitro antagonism of benzodiazepines by harmane and other beta-carbolines. Harmane is clearly a competitive inhibitor of benzodiazepine receptor binding in vitro. Moreover, harmane-induced convulsions can be inhibited reversibly by diazepam in a manner which is consistent with the assumption of competitive antagonism in vivo. For some beta-carboline derivatives a correlation was found between the affinity for the benzodiazepine receptor in vitro and the convulsive potency in vivo. Thus, the data reported suggest that harmane or other related beta-carbolines are putative endogenous agonists of the benzodiazepine receptor. This suggestion is further supported by the observation that diazepam is equally potent in inhibiting harmane- or picrotoxin-induced convulsions, indicating a convulsive mechanism within the GABA receptor-benzodiazepine receptor system.

1-Methyl-beta-carboline (harmane), a potent endogenous inhibitor of benzodiazepine receptor binding.

The interaction of several beta-carbolines with specific [3H]-flunitrazepam binding to benzodiazepine receptors in rat brain membranes was investigated. Out of the investigated compounds, harmane and norharmane were the most potent inhibitors of specific [3H]-flunitrazepam binding, with IC50-values in the micromolar range. All other derivatives, including harmine, harmaline, and several tetrahydroderivatives were at least ten times less potent. Harmane has been previously found in rat brain and human urine, so it is the most potent endogenous inhibitor of specific [3H]-flunitrazepam binding known so far, with a several fold higher affinity for the benzodiazepine receptor than inosine and hypoxanthine. Thus, we suggest that harmane or other related beta-carbolines could be potential candidates as endogenous ligands of the benzodiazepine receptor.

Azapropazone binding to human serum albumin.

Azapropazone, a new non-steroidal antiinflammatory drug, is strongly bound to human serum albumin. As revealed by Scatchard analysis, one high-affinity binding site with an association constant of about 1.2 x 10(6)M-1 and two low-affinity binding sites with association constants of about 0.05 x 10(6)M-1 were found. While the high-affinity binding site of azapropazone is clearly not identical with the diazepam or digitoxin binding sites of human serum albumin, contradictory evidence was found by optical measurements and displacement studies for the similarity of the azapropazone and the warfarin binding site of human serum albumin. At present, it is suggested that both drugs bind to different areas of the same binding site. Therefore, the pronounced effects of various disease states on the plasma protein binding of azapropazone can not be explained by a binding to an unusual binding site, but seem to be due to an extreme sensitivity of the azapropazone binding area to the putative endogenous binding inhibitors, present in the blood during those disease states.

A highly reactive tyrosine residue as part of the indole and benzodiazepine binding site of human serum albumin.

The interaction of L-tryptophan and four benzodiazepine derivatives with tyrosine-modified human serum albumin was investigated by equilibrium dialysis and circular dichroism measurements. Out of the 18 tyrosine residues of the human serum albumin molecule, only 9 could be modified with tetranitromethane. At least up to a degree of modification of 5, the conformation of human serum albumin was not changed and no crosslinking and fractionation has been found, as revealed from circular dichroism measurements in the far ultraviolet range and from SDS polyacrylamide electrophoresis. The modification of only 2 out of the 9 accessible tyrosine residues of human serum albumin strongly affects the binding of L-tryptophan and diazepam to their common, stereospecific bindining site. This was evidently shown by a reduction of the association constants by more than 90% and by a large reduction of the extrinsic Cotton effects of four benzodiazepines bound to human serum albumin. The numbers of binding sites remained unchanged. Strong evidence was presented that only one tyrosine residue, which reacts faster with tetranitromethane than all others, is mainly involved in the specific indole and benzodiazepine binding site of human serum albumin. The location of this highly reactive tyrosine residue and that of the specific indole and benzodiazepine binding site within the human serum albumin primary structure is discussed.