Nonisothermal fluctuating hydrodynamics and Brownian motion.

The classical theory of Brownian dynamics follows from coarse graining the underlying linearized fluctuating hydrodynamics of the solvent. We extend this procedure to globally nonisothermal conditions, requiring only a local thermal equilibration of the solvent. Starting from the conservation laws, we establish the stochastic equations of motion for the fluid momentum fluctuations in the presence of a suspended Brownian particle. These are then contracted to the nonisothermal generalized Langevin description of the suspended particle alone, for which the coupling to stochastic temperature fluctuations is found to be negligible under typical experimental conditions.

Effective temperatures of hot Brownian motion.

We derive generalized Langevin equations for the translational and rotational motion of a heated Brownian particle from the fluctuating hydrodynamics of its nonisothermal solvent. The temperature gradient around the particle couples to the hydrodynamic modes excited by the particle itself so that the resulting noise spectrum is governed by a frequency-dependent temperature. We show how the effective temperatures at which the particle coordinates and (angular) velocities appear to be thermalized emerge from this central quantity.

Effects of fenoldopam on myocardial function (strain rate) in patients with coronary artery disease undergoing cardiac surgery.

BACKGROUND: This study aimed to assess the effects of fenoldopam, an antihypertensive agent with nephroprotective properties, on myocardial function. The global systolic and diastolic function and the strain rate, a new parameter used to quantify regional myocardial function, were measured with transesophageal echocardiography. METHODS: Forty patients undergoing elective coronary artery surgery were analyzed in a prospective nonrandomized clinical trial. Patients were divided into two groups, a group that received 0.05-mcg/kg/min fenoldopam (20 patients) and a control group (20 patients). Only patients with serum creatinine levels > or =120 micromol/L and critical coronary stenosis were selected. The ejection fraction (EF), the E and A waves, and the E/A ratio were measured with transesophageal echocardiography, and the strain rate was calculated using a strain quantification program to measure the peak systolic strain rate (PSSR) and the peak diastolic strain rate (PDSR). RESULTS: Fenoldopam did not change the systolic and diastolic global function (EF, E wave, A wave and E/A). Regarding regional myocardial function, fenoldopam significantly increased the PSSR from -1.09+/-0.8 1/s to -2.24+/-2.26 1/s (P=0.038) and the PDSR from 1.04+/-0.69 1/s to 1.69+/-0.87 1/s (P=0.012). CONCLUSION: Low doses of fenoldopam increased the regional myocardial function, as assessed by the myocardial strain rate, in patients undergoing cardiac surgery.

Ventriculo-arterial coupling and mechanical efficiency with remifentanil in patients with coronary artery disease.

BACKGROUND: Optimum transfer of energy from the left ventricle to the arterial circulation requires appropriate matching of these mechanical systems. Left ventricular-arterial coupling describes this relationship between the ventricular elastance (Ees) and arterial elastance (Ea). The ratio of these elastances defines the efficiency of myocardium and provides in our study a useful technique for assessment of the actions of remifentanil. The purpose of this study was to evaluate the effects of remifentanil on ventriculo-arterial coupling in cardiac surgery in patients with coronary artery disease. METHODS: Fourteen patients with coronary artery disease, submitted intraoperatively to cardiac anesthesia for myocardial revascularization, were examined prospectively. With the use of transesophageal echocardiography (TEE) and different dicrotic arterial pressures, we determined the ventricle elastance (Ees), the arterial elastance (Ea) and myocardial efficiency before and after administration of a slow-bolus of remifentanil (1 micro kg(-1)). RESULTS: Remifentanil decreases significantly the ventricular elastance (from 6.09 mmHg ml-1 m(-2) to 4.88) (P < 0.05), with a less, but however, significant decrease of arterial elastance (from 3.68 mmHg ml(-1) m(-2) to 3.13) (P < 0.05). Despite causing simultaneous declines, maintains a good myocardial efficiency (0.64-0.68) with no significant difference. CONCLUSION: Although remifentanil depresses ventricular and arterial elastance, preserves a good left ventricular-arterial coupling and mechanical efficiency, despite a little increase of coupling. However, these effects are maintained only during a slow intravenous infusion and are dose-dependent with impairment of coupling, that may contribute to decline in overall cardiovascular performance, at higher anesthetic dose and rapid infusion in patients with a severe myocardial dysfunction.

Ineffectiveness of probiotics in preventing recurrence after curative resection for Crohn's disease: a randomised controlled trial with Lactobacillus GG.

BACKGROUND AND AIMS: Experimental studies have shown that luminal bacteria may be involved in Crohn's disease. Probiotics are a possible alternative to antibiotics. The aim of this randomised placebo controlled study was to determine if Lactobacillus GG, given by mouth for one year, could prevent Crohn's recurrent lesions after surgery or to reduce their severity. METHODS: Patients operated on for Crohn's disease in whom all of the diseased gut had been removed were randomly allocated to receive 12 billion colony forming units of Lactobacillus or identical placebo for one year. Ileocolonoscopy was performed at the end of the trial or at the onset of symptoms. Endoscopic recurrence was defined as grade 2 or higher of Rutgeerts scoring system. RESULTS: Eight of 45 patients were excluded from the trial (three for non-compliance and five for protocol violations). Clinical recurrence was ascertained in three (16.6%) patients who received Lactobacillus and in two (10.5%) who received placebo. Nine of 15 patients in clinical remission on Lactobacillus (60%) had endoscopic recurrence compared with six of 17 (35.3%) on placebo (p=0.297). There were no significant differences in the severity of the lesions between the two groups. CONCLUSIONS: Lactobacillus GG seems neither to prevent endoscopic recurrence at one year nor reduce the severity of recurrent lesions.

Review article: Immunosuppressants in distal ulcerative colitis.

BACKGROUND: Distal ulcerative colitis may prove to be resistant to steroids and aminosalicylates, but total colectomy is more difficult to justify than in severe extensive colitis. Immunosuppression is of established benefit in generalized colitis, but there are no data available specific to distal disease. AIM: To determine whether the protocol-driven use of immunosuppressants in resistant distal ulcerative colitis is of similar efficacy and safety to that in extensive disease. METHODS: Two hundred and twenty-eight patients with distal ulcerative colitis seen in a 5-year period were identified from a prospective database. Details of 52 who had received immunosuppression were analysed. RESULTS: The 52 patients received 68 courses of therapy (53 azathioprine, five mercaptopurine, 10 ciclosporin). The thiopurines yielded clinically valuable responses in only 43% of courses, with failure of response in 16% and toxicity in 34%. Ciclosporin was helpful on only two of 10 occasions. Eight patients required total colectomy. Adverse events were typical of those normally associated with immunosuppressants, with potential risk to life in seven patients; treatment was discontinued because of toxicity on a total of 31% of occasions. CONCLUSIONS: Immunosuppression appears to be of lower efficacy and higher toxicity in resistant distal colitis than when used in more extensive colitis.

[Ultrasonography in the diagnosis of enterocutaneous fistula in Crohn's disease]. / L'ecografia nella diagnosi delle fistole enterocutanee nella malattia di Crohn.

INTRODUCTION: Perforation seems to be a specific pathologic aspect in some types of Crohn's disease. Fistulae are caused by a transmural extension of a fissure and/or an ulcer; they are often multiple and can be internal or external. External fistulae usually occur after surgery and along the scar incision. They are frequently complicated by associated intra-abdominal abscesses. We investigated the accuracy of fistulography by ultrasonography compared to fistulography by X-rays in the diagnosis of enterocutaneous fistulae. MATERIAL AND METHODS: Eight patients resected for Crohn's ileitis and with enterocutaneous fistulae were examined by fistulography with ultrasonography and then by fistulography with X-rays. Disease recurrence was established with ultrasonography on ileum anastomosis in all patients. A7.5 MHz linear transducer was connected to a videotape. Physiologic solution was injected into the cutaneous orifice using a thin rigid catheter to evaluate the communication with the intestinal tract by fistulography. At the same time all patients underwent fistulography with contrast agent injection through a radiopaque catheter. RESULTS: On the same day two radiologists performed the ultrasonographic and the radiologic examinations and had 100% agreement between the two methods. In five of eight patients (62%) there was no intestinal communication. Ultrasonography showed hypoechoic lines turning deeply from the cutaneous surface with no communication with the intestinal tract. Radiology confirmed the ultrasonography diagnosis. In two of five patients the fistulae ended in small abscesses. The patients had been treated with immunosuppressive or parenteral therapy; four of them improved and one underwent abscess drainage. In three of eight patients cutaneous fistulae communicated with the intestinal anastomosis. In one patient there was an abscess with multiple fistulae, one of which communicated with the third duodenal segment. DISCUSSION: The origin, anatomic course and sites of communication of fistulae should be evaluated with conventional barium studies first. These studies may be limited by the fact that the origin of the fistulae could be edematous and prevent contrast opacification, in which cases conventional fistulography or ultrasonographic fistulography should be performed. CONCLUSIONS: Our experience suggests that ultrasonography is a reliable method for detecting intestinal alterations and especially the complications typical of Crohn's disease such as enterocutaneous fistulae.

Role of ultrasonography in the diagnosis of postsurgical recurrence of Crohn's disease.

OBJECTIVE: Ultrasonography is a valid tool in the diagnosis of Crohn's disease, but its sensitivity, specificity, and overall accuracy in the diagnosis of postoperative recurrence are still not well established. The aim of this study was to evaluate the accuracy of ultrasonography compared with endoscopy in the diagnosis of postoperative recurrence of Crohn's disease. METHODS: Forty-seven patients resected for Crohn's ileitis were studied by ultrasonography and colonoscopy to detect possible recurrence of the disease; 10 patients operated on for cancer of the right colon were used as controls. Six patients with Crohn's disease were excluded from the study because of failure to endoscopically reach the anastomosis; the remaining 41 patients had both ultrasonography and colonoscopy over a period of 14 days. Sonographic recurrence was defined as the presence of >5 mm thickness of the ileal wall. RESULTS: Sensitivity, specificity, and overall accuracy of ultrasonography in diagnosis of postoperative recurrence were 81%, 86%, and 83% respectively. Positive predictive value was 96% and negative predictive value was 57%. CONCLUSION: This study is the first to assess the role of ultrasonography in comparison with endoscopy in detecting Crohn's disease recurrence after surgery. Our data suggest that ultrasonography should be used first in the case of clinical suspicion of Crohn's disease recurrence, reserving ileocolonoscopy for negative or uncertain cases.

Use of antibiotics in the treatment of active Crohn's disease: experience with metronidazole and ciprofloxacin.

BACKGROUND AND AIMS: The use of antibiotics in the treatment of active Crohn's disease has recently increased on the assumption that enteral flora may play a role in the origin of symptoms and/or complications of Crohn's disease. The aim of this study was to evaluate retrospectively the efficacy of metronidazole and/or ciprofloxacin in the treatment of acute phases of Crohn's disease. METHODS: The clinical records of 233 inpatients seen at our clinic for active Crohn's disease and treated with metronidazole and/or ciprofloxacin (1 g daily each) during the period 1984-1996 were reviewed; the patients were divided into three groups according to antibiotic therapy. The primary criterion of success was the achievement of a complete or partial remission evaluated on the basis of the Simple Index; a secondary criterion of success was the efficacy of therapy on individual symptoms and signs. RESULTS: Similar rates of success were obtained with the three schemes of treatment: 70.6% with antibiotic combination, 72.8% with metronidazole, 69.0% with ciprofloxacin. The most frequent symptoms and signs such as diarrhoea, abdominal pain, fever, abdominal mass and abscesses improved in about 60% of patients in the three groups. Remission time after antibiotic treatment was about one year. Side effects requiring discontinuation of therapy occurred in about 20% of patients. CONCLUSIONS: Metronidazole and ciprofloxacin seem to be useful in treating active phases of Crohn's disease. These results strongly support the important role of faecal flora in causing Crohn's disease symptoms.