To characterize the relative toxicity of different bile salts, isolated hepatocytes were incubated with different concentrations of one bile salt or with identical concentrations of different bile salts and their conjugates. Incubation lasted for 1 hr; samples were taken at intervals and studied for enzyme release, urea synthesis and stimulation by glucagon, and by electron microscopy. While the trihydroxylated bile salt, taurocholate, did not produce alterations at concentrations up to 1,500 microM, the dihydroxylated salts, chenodeoxy- and deoxycholate, caused enzyme release and membrane lysis, and inhibited urea synthesis at concentrations above 500 microM. In contrast, ursodeoxycholate was ineffective at concentrations up to 1,500 microM. Conjugation of these bile salts did not result in significant differences with the exception of deoxycholate conjugates which induced enzyme leakage more rapidly. Studies of lipid membrane vesicles revealed corresponding alterations. The monohydroxylated salt, taurolithocholate, caused cellular damage as indicated by enzyme loss and impairment of hormonal sensitivity of cells at low concentrations (30 to 100 microM). Dihydroxylated salts produced a different time course of membrane leakage, ultrastructural changes and release of volume marker and lipid in liposomes, suggesting a possible different mechanism of damage induced by this bile salt. Both systems can readily be used to study bile salt membrane interactions.

Animals↗

PubMedDate not supplied

Inhibition of 5-HT3 receptor function by imidazolines in mouse neuroblastoma cells: potential involvement of sigma 2 binding sites.

The influence of several imidazolines and sigma-site ligands on cation influx through the 5-HT3 receptor channel in N1E-115 mouse neuroblastoma cells was studied by measuring the 2-min influx of the organic cation [14C] guanidinium induced by 1 microM 5-HT (in the presence of 10 microM substance P in all experiments). In addition, we determined specific binding of [3H]DTG (1,3-di(2-tolyl)-guanidine), a selective sigma-site radioligand, and [3H] GR65630 (3-(5-methyl-1H-imidazol-4-yl)-1-(1-methyl-1H-indol-3-yl)-1- propanone), a selective 5-HT3 receptor antagonist, to membranes prepared from N1E-115 cells. The 5-HT-induced [14C]guanidinium influx was inhibited by the imidazolines, ondansetron, antazoline, idazoxan, BDF 6143 (4-chloro-2-(2-imidazolin-2-ylamino)-isoindoline), cirazoline, naphazoline, clonidine and by the guanidine agmatine, but not by the catecholamine adrenaline. The inhibitory effect of the imidazolines on cation influx through the 5-HT3 receptor channel was mimicked by the sigma-site ligands, (+/-)-ifenprodil, (+)-3-PPP ((R)-3-(3-hydroxyphenyl)-N-propylpiperidine), DTG (1,3-di-tolyl-guanidine). haloperidol, dizocilpine, and ketamine as well as by the polyamines, arcaine and spermidine.-Ondansetron inhibited [3H]GR65630 binding with high affinity, whereas inhibition of binding of this radioligand to the 5-HT3 receptor by antazoline, BDF 6143, idazoxan, cirazoline, (+/-)-ifenprodil, (+)-3-PPP, DTG and haloperidol occurred in the high micromolar range. In the competition experiments with [3H]DTG, (+/-)-ifenprodil, haloperidol, unlabelled DTG, BDF 6143 and (+)-3-PPP inhibited binding of the radioligand at moderate affinity (Ki values in the range of 1 microM or lower), whereas ondansetron, antazoline, idazoxan, cirazoline, naphazoline, clonidine, tolazoline, efaroxan, RX821002 (2-[2-(2-methoxy-1,4-benzodioxanyl)]imidazoline), ketamine and spermidine exhibited affinity, in the high micromolar or millimolar range only. Comparison of the potencies of the ligands (pIC50% values) in inhibiting 5-HT-induced [14C]guanidinium influx with their affinities (pKi values) at the 5-HT recognition sites of the 5-HT3 receptor and at the sigma 2-sites of the N1E-115 cells by means of multiple regression analysis revealed a significant correlation with the affinities at both sites. In conclusion, our data suggest that imidazolines and sigma-ligands, which as a rule possess low affinity for the 5-HT recognition site of the 5-HT3 receptor, may be assumed to exert their inhibitory effect on cation influx through the 5-HT3 receptor channels, at least in part, by interacting with sigma 2-binding sites.

Animals↗

PubMedDate not supplied

Regional variation in the use of antibiotics in four Danish hospitals.

The increasing use of antibiotics contributes to the selection of resistant bacteria and to the cost of health care. Large regional differences in the use of antibiotics between and within countries exist. This study describes such usage in four Danish hospitals, and includes a comparison with that of the average of 450 US hospitals. Compared to the Danish hospitals, the US hospitals used approximately double the amount of antibiotics in defined daily dosages (DDD)/100 bed days. In contrast to the comparison with the American hospitals no real differences were found comparing the four Danish hospitals. The four Danish hospitals differed in degree of specialization, presence of a clinical microbiological department or a hospital pharmacy. Use of antibiotics, in DDD/100 bed days, was highest in the hospital without a department of clinical microbiology, while the highest cost of antibiotics/admission was found in the hospital with the highest degree of specialization. Restraint in antibiotic usage calls for the joint efforts of the department of clinical microbiology, the hospital pharmacy and the local drug committee - the most important tools being: continuous education, audits of antibiotic use, provision of guidelines and recommendations, facilities for rapid diagnosis of infectious diseases, and limitation of the number of antibiotics used in routine sensitivity testing.

Anti-Bacterial Agents↗

PubMedDate not supplied

The role of shock in the pathogenesis of fat embolism after trauma.

Experimental studies and pathological investigations indicate that intrusion of fat into the circulation is common after trauma. This may not have any effect unless frank hypovolaemia supervenes upon changes in the blood vessels, manifested by a deficient vasomotility in shock. After fat embolism disseminated intravascular coagulopathy may occur as a consequence of the haematological changes and disturbances of capillaries. The morphological appearance of massive post-traumatic fat embolism evolves from the compensatory effect of accumulated synergistic factors that primarily induced the changes. From this point of view fat embolism should be recognized in the additional important role of an epiphenomenon of post-traumatic shock.

Embolism, Fat↗

PubMedDate not supplied

Quantification of transient quadratic phase couplings within EEG burst patterns in sedated patients during electroencephalic burst-suppression period.

The time dynamics of the quadratic phase coupling within burst patterns during electroencephalic burst-suppression has been quantified. It can be shown that a transient quadratic phase coupling (QPC) exists between the frequency ranges 0 to 2.5 and 3 to 7.5 Hz and between the frequency ranges 0 to 2.5 and 8 to 12 Hz. The QPC can be explained by an amplitude modulation, where the slow rhythm modulates the rhythmic activities with a higher frequency. By means of time-variant bicoherence analysis, a strong phase-locking between the modulating and the modulated component can be identified. The phase-locking is demonstrable within the first 250 ms after the burst onset and comes up to the maximum between 750 and 1250 ms. The effect is maintained over the whole first part of the burst (2 s) with a decreasing tendency after 1250 ms. All these effects cannot be found in the EEG before entering the burst suppression period (BSP). The transient coupling phenomena in the EEG bursts during BSP can be regarded as indicators for short-term interrelations between the underlying electrophysiologic processes.

Brain↗

PubMedDate not supplied

Developmental changes in the complexity of the electrocortical activity in foetal sheep.

The foetal sheep brain develops organised sleep states from 115-120 d gestational age (dGA, term 150 dGA) alternating between REM and NREM sleep. We aimed to investigate whether maturation of REM or NREM sleep generating structures leads to the development of distinct sleep states. The electrocorticogram (ECoG) was recorded from five unanaesthetised chronically instrumented foetal sheep in utero and was analysed every 5th day between 115-130 dGA by two different non-linear methods. We calculated a non-linear prediction error which quantifies the causality of the ECoG and applied bispectral analysis which quantifies non-linear interrelations of single frequency components within the ECoG signal. The prediction error during REM sleep was significantly higher than during NREM sleep at each investigated age (P<0.0001) coincidental with poor organisation of the rhythmic pattern in the ECoG during REM sleep. At 115 dGA, organised sleep states defined behaviourally were not developed yet. The prediction error, however, showed already different states of electrocortical activity that were not detectable using power spectral analysis. The prediction error of the premature NREM sleep ECoG decreased significantly during emergence of organised sleep states between 115 and 120 dGA and continued to decrease after the emergence of distinct sleep states (P<0.05). The prediction error of the premature REM sleep ECoG did not change until 120 dGA and began to increase at 125 dGA (P<0.05). Using bispectral analysis, we showed couplings between delta waves (1.5-4 Hz) and frequencies in the range of spindle waves (4-8 and 8-12 Hz) during NREM sleep that became closer during development. The results show that maturation of ECoG synchronisation mediating structures is important for the development of organised sleep states. The further divergence of the prediction error of NREM and REM sleep after development of organised sleep states reveals continuous functional development. Thus, complementary application of non-linear ECoG analysis to power spectral analysis provide new insights in the collective behaviour of the neuronal network during the emergence of sleep states.

Algorithms↗