Mechanisms of intra-dialyser granulocyte activation: a sequential dialyser elution study

INTRODUCTION: During haemodialysis (HD), an early and transient white blood cell (WBC) reduction is noted in the peripheral blood, which has been attributed mainly to the sequestration of polymorphonuclear cells (PMN) in the pulmonary vasculature. However, WBC also adhere to the dialyser, as demonstrated before in an elution study performed after HD. In the present study, we investigated if intradialyser WBC sequestration contributes to the WBC nadir in the blood shortly after the start of HD and whether or not different mechanisms underlie PMN adherence in dialyser and lung. In addition, PMN degranulation was analysed not only in peripheral blood but also in dialyser eluates (DE). SUBJECTS AND METHODS: Dialysers were eluted after 7 1/2 (DE-7 1/2) and 180 (DE-180) min of HD in eight patients. Blood samples were taken before HD (t0), and at t7 1/2 and t180. Besides WBC count and differentiation, PMN adhesion (CD11b and CD62L) and degranulation markers (CD63 and CD66b) were assessed by flow cytometry. RESULTS: In the blood, a WBC fall was noted at t7 1/2 (from 5.8 to 4.8 x 10(9)/l; absolute about 5 x 10(9) cells). DE contained 3.0 x 10(6) cells at t7 1/2, and 57.2 x 10(6) at t180 (P = 0.015). As for CD11b, at t7 1/2 both in the blood and DE an increased expression was observed, as compared to t0 (P = 0.01); CD11b expression in DE-7 1/2 was higher than in DE- 180 (P = 0.025). In contrast, CD62L showed downregulation only in DE both at t7 1/2 (mean fluorescence intensity (MFI) PB 4172 and DE-7 1/2 2353, P = 0.01), and at t180 (MFI 794, P = 0.03 versus DE-7 1/2), when compared to blood at t0. As for degranulation markers, an increase was observed in blood at t7 1/2 (MFI CD63 from 357 to 506, P = 0.02; CD66b from 507 to 794, P = 0.001), in comparison with t0. Eluted PMN at t7 1/2 showed a higher expression of CD63 than PMN in blood at t7 1/2 and DE-180 (MFI in DE-7 1/2 1280 and blood 506, P = 0.003). The expression of CD66b was increased in DE-7 1/2 (MFI 1803 versus blood 794, P = 0.01), and even more in DE-180 (MFI 2763, P = 0.002), when compared to blood. CONCLUSIONS: From these data it is concluded first, that intradialyser PMN sequestration does not contribute markedly to the WBC nadir in the circulation. Second, intradialyser PMN trapping appears to result primarily from non-adhesion-molecule-mediated factors, as indicated by an increased expression of CD11b at t7 1/2 on eluted PMN associated with low cell numbers in DE, and normalized CD11b expression at t180 associated with considerably higher cell numbers in DE. Third, HD-induced degranulation seems to be a complex phenomenon. After a rapid transient onset, characterized by an early upregulation of CD63 and CD66b on PMN leaving the dialyser, degranulation continues within the device as indicated by an additional rise in the expression of CD66b on PMN in DE-180.      

Mutagenicity testing of organic extracts of diesel exhaust particles after fractionation and recombination

A new strategy for the evaluation of mixtures is presented. The mixture used was the organic extract of diesel exhaust particles (DEP). After extraction with dichloromethane (DCM), the crude extract was fractionated according to polarity into five fractions: aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, dinitro-PAHs, and polar compounds. After dissolving in dimethylsulphoxide␣(DMSO), the three fractions containing the primary mutagens (fractions 3–5) were recombined in different combinations to create new extracts. The blend matrix was obtained using a mixture design at three dose levels to support an empirical model with linear, interaction, and quadratic terms (Taylor polynome). The recombined extracts were tested in the Ames Salmonella assay using strain TA100. Multivariate data analysis was performed with projections to latent structures (PLS). The best model describing the relation between the mutagenicity (response) and the three fractions (variables) contained two interaction terms. The model showed high correlation (r ²) and prediction properties (Q ²), the latter obtained after cross validation. Interaction terms are only indications of possible synergism or antagonism and have to be evaluated with respect to dose-additivity and response-additivity. The incorporation of dose in the design reduced the number of samples (recombined extracts) significantly, compared to determining dose-response curves on each sample (i.e. the recombined extracts in different dilutions). Furthermore, instead of running two independent experiments as required in the standard procedure for the Ames test, predictions and verifications of a few new samples were used. The principle of fractionation and recombination, and the use of mixture design may in principle be extended to an unlimited number of variables. An adaptation of mixture design to the isobole method is discussed. Received: 16 July 1996 / Accepted: 27 September 1996     

The behavioural response to intrathecal serotonin is changed by acute but not by repeated treatment with zimelidine or metergoline.

The behavioural response to intrathecal serotonin (5-HT) was examined in mice after acute and after withdrawal of repeated treatment with the 5-HT uptake inhibitor zimelidine or the 5-HT receptor antagonist metergoline. Intrathecal 5-HT elicits a response consisting of biting or licking of the lower part of abdomen and reciprocal hindlimb scratching, indicative of nociceptive stimulation. Acute injection of zimelidine (20 mg/kg) significantly increased the response to intrathecal 5-HT (0.25-1 micrograms) whereas a single dose of metergoline (5 mg/kg) completely blocked the response to intrathecal 5-HT (2 micrograms). The behavioural response to intrathecal 5-HT (0.25-2 micrograms) was not significantly changed 48 hr after withdrawal of repeated treatment with zimelidine (2 x 10 mg/kg/day for 14 days) or metergoline (2 x 2.5 mg/kg/day for 14 days). In the present experiments acute zimelidine appeared to increase nociceptive responsiveness, whereas metergoline had the opposite effect. This study does not provide evidence that long-term treatment with zimelidine or metergoline leads to adaptive changes in the response to spinal cord 5-HT receptor stimulation.     

Wallerian degeneration: evaluation with MR imaging

Twenty-three patients who underwent routine magnetic resonance (MR) imaging of the brain were found to have signal or structural abnormalities corresponding to white matter tracts. Images were evaluated for anatomic and MR signal characteristics of the involved tract, associated primary lesions, and, when possible, changes in MR signal and anatomic structures with time. Images from 20 patients demonstrated a thin band of abnormal signal contiguous with the primary lesion and conforming to the known anatomic pathway of a white matter tract. Cerebral infarction was the most common associated primary disorder (n = 17). Neoplasms (n = 2), demyelinating (n = 1) and posthemorrhagic (n = 2) conditions, and an idiopathic movement disorder (n = 1) were associated with white matter tract signal abnormalities that were indistinguishable from those seen with infarction. Signal abnormality corresponding to the corticospinal tract was the type most commonly seen. No change in signal characteristics was seen with time (six cases) or following contrast material administration (two cases). The authors conclude that MR imaging provides a sensitive method of evaluating wallerian degeneration in the living human brain.     

Decreased central dopaminergic activity in essential hypertension

Baseline serum prolactin (PRL) was found to be similar in 35 men with untreated essential hypertension (149 +/- 2/98 +/- 1 mmHg; means +/- s.e.) and 44 healthy normotensive men (126 +/- 1/80 +/- 1 mmHg), all 40 years old. A correlation between baseline PRL and aldosterone was found in the normotensive (r = 0.534, P less than 0.001), but not in the hypertensive group (r = -0.011, NS). Ten subjects from each group received intravenous metoclopramide, a competitive dopamine antagonist, while another 12 normotensive subjects were given saline only, and the effect on PRL, vasopressin (AVP) and catecholamines was followed. An exaggerated PRL response to metoclopramide was observed in the hypertensive group compared with the normotensive (P less than 0.05), and the mean normotensive peak value never exceeded the hypertensive. Plasma noradrenaline increased significantly compared with baseline (P less than 0.05) and the control group (P less than 0.001), concomitant with increased heart rate (P less than 0.05), after the administration of metoclopramide both in the hypertensive and normotensive group. After intravenous injection of metoclopramide, forearm blood flow increased significantly by 50% in the hypertensive (P less than 0.001), and 80% in the normotensive group (P less than 0.001) compared with the control group. Mean blood pressure remained unchanged as did plasma AVP, dopamine and adrenaline. The present study indicates an altered central dopaminergic activity in essential hypertension. Even at rest, endogenous dopamine exerts a modulating effect on noradrenaline release in both hypertensive and normotensive men.     

Characteristics of patients operated on because of suspected arterial embolism: a multivariate analysis

In order to improve the understanding and classification of patients with suspected arterial embolism, we performed a loglinear analysis to study the interactions among eight characteristics in 202 patients operated on as a result of this diagnosis. Female patients were generally older, were in a poorer cardiac state (NYHA class), and had shorter duration of symptoms before operation than male patients. Atrial dysrhythmias were more common in women than in men less than 75 years of age. After the age of 75, however, the incidence was similar in both sexes. Thus, apparently, poor cardiac function is more commonly associated with acute arterial occlusion in women than in men. In men arterial thrombosis secondary to arteriosclerotic occlusive disease may be more frequent. Ischemic heart disease, age of more than 75 years, and the fact that the patient was a woman were independent predictors of poor cardiac function. Atrial dysrhythmias increased the odds for proximal arterial occlusion compared with distal occlusion, but only in NYHA class 1-2, which suggests that low cardiac output might be of importance in distal thrombotic occlusion in patients with both atrial dysrhythmia and poor cardiac function. Patients with arteriosclerosis had symptoms of longer duration than patients without arteriosclerosis and men had symptoms of longer duration than women, which indicate that the diagnosis was more uncertain, or the disease less severe, in these patients. In patients without evidence of ischemic heart disease, poor cardiac function was a predictor of short duration of symptoms, which suggests that patients with nonatherosclerotic heart disease were correctly treated for arterial emboli without undue delay.