Propofol influences the electroretinogram to a lesser degree than thiopentone

Background: The Electroretinogram (ERG) is used clinically to assess the function of retina. Anaesthetic agents are known to affect ERG, and as anaesthesia is often needed in children and uncooperative patients, knowledge about its effects is of clinical importance. Barbiturates selectively depress ERG components, and we compared thiopentone with propofol to assess if the latter preserved retinal function better.
Methods: Ten pigs, average weight 17 kg (SD ± 2 kg) were anaesthetized randomly with propofol 10 mg kg^-1 or thiopentone 30 mg kg^-1. Anaesthesia was maintained by 65% nitrous oxide in oxygen and continuous infusion of the induction agent, i.e. 10 mg kg^-1 h^-1 of propofol, or 10 mg kg^-1 h^-1 for the first hour, then 5 mg kg^-1 h^-1 of thiopentone, with doses being based on pilot studies. After an interval of one week the programme was repeated using the other agent. After 40 minutes dark-adaptation, responses to single flashes of graded intensities from a xenon flashlamp were recorded at five-minute intervals. The a- and b-wave amplitudes and implicit times (time to peak), and a-wave slopes were determined.
Results: The b-wave implicit time was significantly shorter during propofol anaesthesia than when using thiopentone. The effect was most pronounced at the lowest intensities (P < 0.01). No statistically significant differences were found in the amplitudes of the b-waves. The a-wave appeared at lower stimulus intensity (P < 0.05) and the a-wave slopes were significantly steeper (P < 0.01) during propofol anaesthesia.
Conclusion: Propofol accordingly appeared to preserve the photoreceptor response better than thiopentone, and may therefore be considered to be more suitable for ERG recordings than thiopentone.     

Effect of platelet-activating factor (PAF) receptor blockers on smooth muscle cell replication in vitro and allograft arteriosclerosis in vivo

Platelet-activating factor (PAF) stimulates smooth muscle cell (SMC) replication both in vivo and in vitro. In this study we have investigated whether PAF receptor-blocking molecules modulate SMC replication in vitro and the generation of allograft arteriosclerosis in vivo. SMC cultures were established from baby rat aorta media and fibroblast control cultures from the adventitia. Identification of the cultured cell types was determined both by immunohistochemistry and electron microscopy. Both cell types replicated in culture with 10% fetal calf serum (FCS). The addition of PAF-C₁₈ enhanced, and the addition of three PAF receptor inhibitors — WEB 2086, WEB 2170, and BN 50739-reduced, SMC replication and protein synthesis in a dose-dependent fashion in vitro until toxic concentrations were reached. The most potent of these drugs, WEB 2170, was then delivered at the rate of 12 mg/kg per day to recipients of rat aortic allografts. The responses were quantitated by autoradiography after short-term labeling of the recipients with tritium-labeled thymidine (³H-TdR) and by quantitative morphology. Administration of the PAF receptor blocker had no impact on the replication of the inflammatory cells in the allograft adventitia nor on the replication of SMCs in the media and intima. Administration of the PAF receptor blocker delayed the generation of allograft arteriosclerosis slightly, but not significantly. These results suggest that PAF is not an essential component in the inflammatory cascade leading to allograft arteriosclerosis.     

Alcohol Consumption and Alcoholic Liver Disease: Evidence of a Threshold Level of Effects of Ethanol

The effects of long-term moderate or "social" alcohol consumption (10-80 g daily intake) on the incidence of features of alcoholic liver disease (ALD) were delineated in a consecutive autopsy series of 210 males. The subjects' daily intake, as well as duration of alcohol consumption, was determined by an interview with the spouse or a close acquaintance and compared with semiquantitative histological scores for stage of ALD.
No significant increase in the incidence of features of ALD could be related to all-year daily intake of ethanol below 40 g (40 g equals 1.1 liter of beer, 0.44 liter of wine, and 0.11 liter of spirits). However, daily intake between 40–80 g increased relative liver weight on average 3.1 g/kg of body weight (p < 0.02), the frequency of fatty liver from 11.7 to 47.2% [relative risk (RR) = 4.4], and the frequency of mainly slight alcoholic hepatitis up to 16.7% (RR = 7.5). The incidence of both bridging fibrosis and liver cirrhosis increased significantly (RR = 8.8) only when daily intake exceeded 80 g. Amounts of ethanol exceeding 80 g did not relate to further increases in incidence of bridging fibrosis or liver cirrhosis.
These findings suggest that, in males, daily ingestion of ethanol below 40 g for a period of 25 years does not increase the risk of alcohol-related liver disease. In contrast, similar duration of daily intake between 40 and 80 g (mean 61.6 g) increased the risk of all but fibrotic liver lesions of ALD significantly and may thus represent a potential threshold level that significantly increases the risk of alcohol-related liver damage. Moreover, our results may suggest that, on an individual level, the risk function for liver fibrosis may not be directly dose-related, but rather, when a permissive threshold level is attained, further consumption is of no or little importance to the progression of ALD.     

Comparison of nitric oxide donors in lowering intraocular pressure in rabbits: role of cyclic GMP.

L-arginine-nitric oxide (NO) pathway participates in the physiology and in many pathological processes in the eye, such as glaucoma. The aim of the present study was to compare the ocular hypotensive effect of different NO-donors, and to get more information on the role of cyclic guanosine 3',5'-monophosphate (cGMP) in this process. The test compounds were administered topically or intravitreally in the eye of a normotensive rabbit. Intraocular pressure (IOP) was measured with a pneumatonometer after topical anesthesia. The metabolites of NO (nitrite, nitrate, NOx) and cGMP were assayed from the aqueous humor and plasma. NO-synthase (NOS) protein expression was assayed in the ciliary body by Western blotting. The maximal lowering of IOP was achieved as follows: atriopeptin III (concentration 78 (microM, decrease in IOP 50%), atriopeptin II (84 (microM 37%). 8-Br-cGMP (90 mM, 37%), zaprinast + 8-Br-cGMP (1 mM + 90 mM, 34%), L-arginine (1 mM, 29%), SNP (40 mM, 28%), nitrosocaptopril (100 mM, 28%), S-nitrosothiol (SNOG) (10 mM, 27%), YC-1 (10 (microM, 25%), zaprinast + SNP (1 mM + 40 mM, 22%), spermine NONOate (100 mM, 20%) [corrected]. The decrease in IOP lasted for 2-5 hr, except with atriopeptin II and III, when IOP values were first normalized in 6 hr and 2 days, respectively. In conclusion, the results of the present study indicate that by increasing the activity of L-arginine/NO/cGMP-pathway it is possible to lower IOP in rabbits equally to the currently used antiglaucomatous drugs.     

Effects of RM-beta-CD on sublingual bioavailability of Delta9-tetrahydrocannabinol in rabbits.

The purpose of the present study was to develop novel cyclodextrin-containing sublingual formulations of cannabinoids. Complexation of model cannabinoids, Delta(9)-tetrahydrocannabinol (THC) and cannabidiol (CBD), with randomly methylated beta-cyclodextrin (RM-beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD), were studied by the phase-solubility method. Due to better complexation efficiency, RM-beta-CD was selected for further studies. Solid THC/RM-beta-CD and CBD/RM-beta-CD complexes were prepared by freeze-drying. The dissolutions of both THC and CBD in the presence and absence of RM-beta-CD were determined. THC was selected for in vivo studies: the pharmacokinetics of THC after both sublingual and oral administrations of ethanolic THC and THC/RM-beta-CD complex solutions were studied in rabbits. The aqueous solubility of CBD and THC increased as a function of CD concentration, showing A(L)- and A(P)-type diagrams for HP-beta-CD and RM-beta-CD, respectively. Dissolution rates of THC/RM-beta-CD and CBD/RM-beta-CD complexes were significantly (p < 0.05) higher than those of plain THC and plain CBD, respectively. The absolute bioavailability (F) of THC decreased in the following order: sublingual THC/RM-beta-CD solution (F = 12.1+/-1.4%; mean+/-S.D.; n = 4) > oral THC/RM-beta-CD solution (F = 4.0+/-6.0%) > or = sublingual ethanolic THC solution (F = 3.8+/-2.8%) > oral ethanolic THC solution (F = 1.3+/-1.4%). These results demonstrate that RM-beta-CD increases both the aqueous solubility and dissolution rate of these cannabinoids, making the development of novel sublingual formulation possible. These results also suggest that the sublingual administration of a THC/RM-beta-CD complex substantially increases the bioavailability of THC in rabbits.     

Mivacurium When Precedent by Pancuronium Becomes a Long-acting Muscle Relaxant

Background: To ensure rapid recovery of neuromuscular block, it might be useful to administer a short-acting relaxant after a long-acting one. Therefore, the interaction between pancuronium and mivacurium was investigated when mivacurium was administered during the recovery from pancuronium block.

Methods: After written informed consent, 41 adult patients were studied during propofol/alfentanil/nitrous oxide/oxygen anesthesia. Neuromuscular function was monitored using an electromyographic (EMG) method. After a stable EMG calibration response, cumulative doses of pancuronium were given to establish a 95% neuromuscular block. In the control group, an ED95 dose of 100 micro gram/kg mivacurium was administered instead of pancuronium. When the EMG response after pancuronium or mivacurium had recovered to 25% of the baseline, a single randomized intravenous bolus dose of 10 or 70 micro gram/kg mivacurium was given. Thereafter, spontaneous recovery of the neuromuscular function was recorded.

Results: The time from pancuronium until T1 25% EMG recovery was 38 +/-12 min (mean+/-SD). The respective times after 10 or 70 micro gram/kg mivacurium were 28+/-8 and 54+/-7 min in the pancuronium group or 3+/-1 (n = 3) and 10+/-4 min in the mivacurium group (P = 0.0001). Times to 95% EMG recovery after 10 or 70 micro gram/kg mivacurium were 77+/-14 and 97+/-16 min in the pancuronium group and 11+/-3 and 20+/-7 min in the mivacurium group, respectively (P < 0.0001). Recovery indexes after 10 or 70 micro gram/kg mivacurium were 26+/-4 and 22+/- 6 min in the pancuronium group or 7+/-3 (n = 3) and 5+/- 2 min in the mivacurium group, respectively (P < 0.0001). Times from the administration of 10 or 70 micro gram/kg mivacurium until train-of-four ratio 0.7 were 94+/-16 and 111+/-14 min in the pancuronium group and 12+/-4 and 22+/-8 min in the mivacurium group, respectively (P < 0.0001).     

Testicular infarction following ethanol embolization of a renal neoplasm

A case of infarction of the left testis secondary to transcatheter embolization of a malignant left renal tumor with absolute ethanol is presented. The mechanism producing this complication was due to the anomalous nature of the left testicular artery, originating from the left renal artery distal to the site of the balloon occlusion catheter. The importance of this anomaly is discussed and the literature reviewed.     

Histamine in the nervous system of Macoma balthica (Bivalvia)

The distribution of histamine(HA)-immunoreactivity of the molluscan species Macoma balthica was mapped with an antiserum against a histamine-protein conjugate. The main ganglia of the central nervous system of M. balthica, the cerebropleural ganglia, the pedal ganglion and the visceral ganglion all contained strongly HA-positive fluorescent cell bodies. The positive cell bodies were situated in clusters in the outer region of the ganglia. Immunoreactive fibres were located in the inner neuropil region of the ganglia. Also the commissure and the connectives of the ganglia as well as many nerve roots contained HA-positive fibres. These results agree well with the recent finding of the wide distribution of histamine in the nervous system of two marine gastropod molluscs, Aplysia and Pleurobranchaea supporting the thought that histamine has an important role in many physiological function of molluscs.     

Radiographic diagnosis of biceps tendinitis

The radiographic findings and arthrographic image of the intertubercular groove and the biceps tendon were analysed in 143 patients with chronic shoulder pain. Forty-eight patients had been operated on, and of these 33 had tendinitis, caused by attrition in a narrow intertubercular groove in 17 cases, by medial dislocation of the biceps tendon in 11 cases, and by impingement associated with rupture of the rotator cuff in five cases. Plain radiographs revealed degenerative changes in the walls of the groove in half of the patients with biceps tendinitis. A shallow groove was seen in cases of medial dislocation of the biceps tendon, but also in many with a normal tendon. The arthrogram, however, showed whether a shallow groove was associated with dislocation of the tendon. In patients with attrition tendinitis the groove had a depth of 4.8 mm or more or an inclination of the medial wall of 58° or more.

Radiographic measurements of the dimensions of the intertubercular groove may provide valuable information on the state of the biceps tendon.