Smoking protects against ulcerative colitis (UC), and treatment with nicotine patches has a beneficial symptomatic effect in patients with UC. To find an explanation for this response to nicotine in UC, we assessed the effects of nicotine on cytokine production by mononuclear cells (MNC). MNC were isolated from peripheral blood from healthy volunteers. Non-adherent MNC were preincubated with varying concentrations of nicotine or prednisolone for 24 h followed by addition of phytohemagglutinin (10 ~xg/ml). The concentrations of interleukin 2 (IL-2) and tumour necrosis factor-et (TNFa) in the supernatants were determined by ELISA. Nicotine as well as prednisolone caused a significant inhibition of IL-2 and TNFet production. The maximum inhibition caused by nicotine was about 50% of that caused by prednisolone and was reached at concentrations equivalent to nicotine levels measured in plasma of smokers. These results indicate that nicotine exerts its immunoregulatory role through modulation of the cytokine production by non-adherent mononuclear cells.
This study investigated the accuracy and reproducibility of a computer-aided method for quantification of intravascular ultrasound. The computer analysis system was developed on an IBM compatible PC/AT equipped with a framegrabber. The quantitative assessment of lumen area, lesion area and percent area obstruction was performed by tracing the boundaries of the free lumen and original lumen.Accuracy of the analysis system was tested in a phantom study. Echographic measurements of lumen and lesion area derived from 16 arterial specimens were compared with data obtained by histology. The differences in lesion area measurements between histology and ultrasound were minimal (mean _+ SD: -0.27 + 1.79 mm 2, p > 0.05). Lumen area measurements from histology were significantly smaller than those with ultrasound due to mechanical deformation of histologic specimens ( -5.38 + 5.09 mm 2, p < 0.05). For comparison with angiography, 18 ultrasound cross-sections were obtained in vivo from 8 healthy peripheral arteries. Luminal areas obtained by angiography were similar to those by ultrasound ( -0.52 + 5.15 mm 2, p > 0.05). Finally, intra-and interobserver variability of our quantitative method was evaluated in measurements of 100 in vivo ultrasound images. The results showed that variations in lumen area measurements were low (5 %) whereas variations in lesion area and percent area obstruction were relatively high (13 %, 10%, respectively).Results of this study indicate that our quantitative method provides accurate and reproducible measurements of lumen and lesion area. Thus, intravascular ultrasound can be used for clinical investigation, including assessment of vascular stenosis and evaluation of therapeutic intervention.
We examined the in vivo effect of nicotine on the synthesis of (pro)inflammatory mediators by mouse colonic mucosa. The synthesis of lipid mediators such as the prostanoids prostaglandin E2, 6-keto-prostaglandin F1 alpha and thromboxane B2, the 5-lipoxygenase products leukotriene B4 and leukotriene C4 and the platelet activating factor was not affected, whereas the synthesis of the pro-inflammatory cytokines interleukin-1 beta and tumor necrosis factor alpha was completely abolished. The beneficial effects of smoking and nicotine in ulcerative colitis could be attributed to this inhibition.
A middle-aged woman was admitted to the hospital after being found unconscious at home. A brain CT scan excluded an intracranial bleed or other focal abnormality. Laboratory analysis showed hyponatraemia (sodium: 121 mmol L(-1)) and a low plasma osmolality, with normal sodium excretion and urine osmolality. A diagnosis of hyponatraemic coma was made. The patient was treated with water restriction; 24 h later the sodium was 135 mmol L(-1) and the patient was neurologically fully recovered. The patient, who suffered from von Willebrand's disease, had received desmopressin and ibuprofen for analgesia 2 days before after a dental intervention. She had received desmopressin several times in the past without any complications. A few patients treated with desmopressin for coagulation abnormalities have been reported to develop water intoxication and severe hyponatraemia resulting in seizures and coma. By inhibiting prostaglandin synthesis, non-steroid anti-inflammatory agents (NSAIDs) potentiate the effect of water reabsorption in the renal tubules of vasopressin, therefore enhancing water retention. Desmopressin and NSAIDs should not be used in combination in patients with bleeding disorders, but it is often followed in clinical practice. In addition, this is probably not an unusual situation in patients treated with desmopressin for other 'non-haemorrhagic' indications. This report emphasizes the need for practitioners to be aware of this rare but severe complication.
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