Practical value of a new serum digitoxin assay

The purpose of this study was to evaluate a new fluorescence polarization immunoassay, TDx, for digitoxin by comparing the results of this assay with those of a radioimmunoassay (RIA). Thirty-three serum samples were obtained from 15 patients during, and for 4 weeks after, a 4-week course of digitoxin therapy. Each sample was separated by centrifugation, coded, and frozen until analysis. At the time of analysis, each sample was divided and analyzed simultaneously by TDx and RIA. Nine samples yielded results less than 2 ng/ml (limit of assay sensitivity) by one or both methods and were excluded from further data analysis. Linear regression analysis of the results of the remaining 24 paired samples (x = TDx, y = RIA) revealed a strong correlation coefficient of r2 = 0.95, slope = 0.95, and a y intercept of -0.99 (y = -0.99 + 0.95x). Additionally, the TDx results were lower than the RIA values in only five of 33 paired samples; and these occurred in four patients who had a significantly lower mean estimated creatinine clearance than that of the other 11 patients (39.0 +/- 9.1 ml/min/1.73 m2 vs. 63.3 +/- 11.8 ml/min/1.73 m2, p less than 0.01). The TDx system is a comparable alternative to the RIA method, but differences in specificity and sensitivity may exist and should be evaluated more thoroughly.     

Ultrastructural observations of organelle accumulation in the equine recurrent laryngeal nerve

Summary The left recurrent laryngeal nerves from five horses with sub-clinical neuropathy were examined by light and electron microscopy in a study designed to examine accumulation of axonal organelles at paranodal and internodal locations. Transverse sections of the nerve showed scattered fibres with split myelin sheaths and axonal accumulation of organelles. On longitudinal sections these collections were seen to result from an axonal outpouching in which dense lamellar bodies and mitochondria had accumulated. These paranodal collections, which could be found on both sides of the node, were often associated with infoldings of the terminal loops of myelin and with occasional paranodal demyelination. The fact that many of the organelles in the outpouches were lysosomal in nature was confirmed by their positive staining for cathepsin D activity. Longitudinal sections demonstrated a number of axons which were swollen over a long distance and which contained focal accumulations of similar organelles. In places, however, there was a clear separation between these organelles and the cytoskeletal proteins. In each case these swollen axons were surrounded by Schwann cell nuclei and their processes, forming well-ordered onion bulbs. The possibility that these two types of changes, i.e. the paranodal accumulations and the axonal swellings could result from a disturbance in axonal transport in this distal axonopathy is discussed.     

The use of laser-light scattering and controlled shear in platelet aggregometry

Laser-light scattering was used to observe and quantify the dynamics of human blood platelet aggregation in platelet-rich plasma (PRP). Aggregation was performed in a controlled shear environment by placing the PRP in the annular space between a rotating cylindrical rod and a stationary cylindrical tube. The instrument was capable of very sensitive continuous semi-quantitative measurements of chemically-induced microaggregation. As a demonstration of the technique, results are presented for ADP-induced aggregation at doses of 10, 1, and 0.1 microM and collagen-induced aggregation at a dose of 5 micrograms/ml, each at shear rates of 1,000 s-1 and 500 s-1. Extensive aggregation was observed in response to ADP at even the low dose of 0.1 microM, indicating a high sensitivity to microaggregates. The sensitivity of the ultimate size of the ADP-induced aggregates to ADP concentration was shear dependent. The formation of microaggregates by collagen stimulation was shown to be almost immediate, as contrasted with a 10-20 s typical lag when observed turbidometrically. Disaggregation was observed with 1 microM ADP, but this was only partial, as contrasted with the complete recovery of transmittance observed in the turbidometric technique. Electronic particle sizing and counting was employed to semiquantitatively verify the aggregate size distributions found from mathematical conversion of the laser-light scattering data.     

Melatonin modifies the spontaneous multiunit activity recorded in several brain nuclei of freely behaving rats.

Melatonin, a pineal hormone, released photoperiodically, was administered systemically in rats, previously implanted with semimicroelectrodes into six different brain structures. The multiunit electrical activity of these structures was recorded for 10 min before and 60 min after melatonin administration in unanesthetized, freely moving rats. Different melatonin doses (100, 200, 500, and 1000 micrograms/kg) produced changes in the electrical activity of all tested structures. However, amygdala, rostral hypothalamus and mesencephalic reticular formation showed the most important changes. The main effect induced by melatonin was a dose-related decrease of the spontaneous electrical activity. The significance of these effects is discussed within the context of the behavioral and endocrinological effects of melatonin.     

Functional activity of the neutrophils in the bronchoalveolar space in chronic bronchitis and bronchiectasis]

Bronchoalveolar lavage fluid neutrophils were studied by the cytologic methods in 58 patients with chronic bronchitis, 63 ones with bronchiectasis, and 8 normal controls. The study included cytospectrophotometry of myeloperoxidase and alkaline phosphatase activity and estimation of active oxygen-producing cells in the NBT test. Neutrophilic functional activity was different in the patients with chronic bronchitis and bronchiectasis. Neutrophilic myeloperoxidase and alkaline phosphatase activities were lower in the patients with chronic bronchitis than in those with bronchiectasis, whereas the counts of cells active in the NBT test were low in both patient populations.     

Central nervous control of hepatic circulation.

This study was undertaken to assess the role of the hypothalamus and medulla oblongata in regulation of liver circulation in anesthetized dogs. Blood pressure, flow in hepatic artery and portal vein, and shifts of blood volume in the liver were recorded. Stimulation of the anterior hypothalamus produced changes in arterial pressure which were followed by passive changes in hepatic arterial blood flow; changes in hepatic artery resistance were rather small. Stimulation of the medial and posterior hypothalamus increased hepatic arterial resistance by 65-170%. Liver portal blood flow during stimulation of most of the hypothalamic sites decreased, hepatic portal pressure rose and vascular portal venous resistance increased 2.5-3 times. Three areas only (sympatho-inhibitory area, paraventricular and lateral hypothalamic nuclei) when stimulated produced dilatation of hepatic portal and splanchnic vascular beds, thus increasing portal blood flow. All cases of stimulation led to the decrease of blood volume in the liver by 10-36%. Stimulation of medullary structures (n. tractus solitarii, reticular nn.) caused similar changes in hepatic circulation, however the amplitude of reaction was 1.5-6 times smaller than upon hypothalamic stimulation. Central impulses to the hepatic vessels are transmitted by sympathetic adrenergic nerve fibers through vascular alpha-adrenoreceptors. It is concluded that the hypothalamic level of the central nervous system, unlike the bulbar one, exerts considerable, differentiated, well coordinated and to some extent specific influences on hepatic circulation.     

Long-lasting effects of chronic chlorimipramine treatment of rats on exploratory activity on a hole-board, and on immobility in the forced swimming test

The study concerned the effects of acute and chronic clomipramine administration to male rats on exploratory activity in a novel environment (hole-board) and on immobility in the forced swimming test. Acute clomipramine administration did not alter either exploratory activity on a hole-board as measured 3 or 20 h after drug administration, or immobility in the forced swimming test as measured 20 h after drug administration. Approximately 20 h after the last injection of clomipramine, the rats chronically treated with the drug showed reduced exploratory activity on the hole-board. In contrast, chronic clomipramine treatment significantly increased the activity in the forced swimming test. The effects of the drug on exploratory and forced swimming activities persisted for 14 days after the cessation of clomipramine administration. These data indicate that chronic clomipramine administration exerted profound and long-lasting effects on central nervous system function. The long-lasting action of the drug on behaviour in the forced swimming test might explain the long-term beneficial effect of antidepressant drugs in counteracting behavioral depression.     

The hepatotropic properties of nonsteroidal anti-inflammatory agents

The hepatotropic effect of nonsteroidal anti-inflammatory drugs (NSAID) such as indomethacin, voltaren, piroxicam, phenylbutazon, mefenamic acid was studied. It was found that according to their level of the pharmacological protection of the liver against tetrachlormethan these agents may be arranged in the following sequence: mefenamic acid, phenylbutazon, voltaren, piroxicam. The hepatoprotective effect of NSAID correlates with the antioxidant properties and fails to correlate with the antioxidant ones. The hepatotoxic effect of NSAID was determined by their ability to suppress synthesis of prostaglandins.