Chaos and regular dynamics in model multi-habitat plankton-fish communities

This work is focused on the role of diffusive interaction between separate habitats in a patchy environment in plankton pattern formation. We demonstrate that conceptual reaction-diffusion mathematical models constitute an appropriate tool for searching and understanding basic mechanisms of plankton pattern formation and complex spatio-temporal plankton dynamics

Switch from systemic steroids to budesonide in steroid dependent patients with inactive Crohn's disease

BACKGROUND

Steroid dependent patients with Crohn's disease are at high risk of developing glucocorticosteroid induced side effects.

AIMS

We evaluated the possibility of switching from systemic steroids to budesonide (Entocort) in prednisolone/prednisone dependent patients with inactive Crohn's disease affecting the ileum and/or ascending colon.

PATIENTS

Steroid dependent patients with a Crohn's disease activity index </=200 were included.

METHODS

In a double blind multicentre trial, 120 patients were randomly assigned to receive budesonide 6 mg once daily or placebo. Prednisolone was tapered to zero during the first 4-10 weeks and budesonide or placebo was given concomitantly and for a further 12 weeks. Relapse was defined as an index >200 and an increase of 60 points from baseline or withdrawal due to disease deterioration.

RESULTS

After one and 13 weeks without prednisolone, relapse rates were 17% and 32%, respectively, in the budesonide group, and 41% and 65% in the placebo group (95% confidence intervals for the difference in percentages -41%, -8% and -51%, -16%; p=0.004 and p<0.001, respectively). The number of glucocorticosteroid side effects was reduced by 50% by switching from prednisolone and was similar in the budesonide and placebo groups. Basal plasma cortisol increased in both groups.

CONCLUSIONS

The majority of patients with steroid dependent ileocaecal Crohn's disease may be switched to budesonide controlled ileal release capsules 6 mg without relapse, resulting in a sharp decrease in glucocorticosteroid side effects similar to placebo, and with an increase in plasma cortisol levels.

[The role of carnivorous zooplankton in dynamics of trophic interaction of fish and plankton]

A conceptual (minimal) model of the aquatic community is proposed, which includes phytoplankton, zooplankton, fish and fish larvae. It is shown that carnivorous zooplankton increases the system stability when the fish predation changes. As a result, the system collapse followed by algal bloom becomes less probable.

Motional instabilities in prey-predator systems

Differential fluxes can destabilize the locally stable stationary density distributions in interaction systems with diffusion, advection, and/or locomotion of chemical or biological species. By this method they can cause the formation of stationary or travelling spatial structures. Different scenarios of this general mechanism of spatio-temporal pattern formation in reaction-diffusion-advection systems will be demonstrated, using a simple two-species predator-prey system as an example model.

Attachment representation and cortisol response to the adult attachment interview in idiopathic spasmodic torticollis

OBJECTIVE

The study investigates individual differences in the mental representation of attachment and their impact on the cortisol response to psychosocial stress in idiopathic spasmodic torticollis (IST). It was hypothesized (a) that in IST insecure attachment is more prevalent than in a non-clinical control group and (b) that subjects with dismissing attachment respond with higher physiological arousal to a specific stimulus activating the attachment behavioural system than subjects with secure attachment.

METHOD

20 patients with IST and 20 healthy controls matched for age and sex underwent the Adult Attachment Interview, an hour-long, semiclinical interview on attachment experiences. During the interview salivary cortisol levels were monitored. The subjects' mental state with regard to attachment was classified using the attachment Q-sort method. Anxiety and depression were measured as potential covariates of the adrenocortical stress response.

RESULTS

Compared to the non-clinical group, dismissing attachment was strongly overrepresented in IST. In IST, but not in the healthy control group, dismissing attachment correlated with an elevated cortisol response to the interview.

CONCLUSION

In clinical, but not in non-clinical samples dismissing attachment may be associated with increased vulnerability to psychosocial stress. The factors contributing to this interaction are not yet fully elucidated.

[Dependence of the fish school movement and plankton special distribution on the phytoplankton growth rate]

In this paper we investigate the spontaneous emergence and the dynamics of patchiness in spatially distributed communities of plankton, which plays a key role in the matter rotation on earth. Patchiness is often supposed to be due to hydrodynamical factors (diffusion and advection). In contrast to this approach, we consider the formation of plankton patches as a result of interactions in the trophic chain nutrient--phytoplankton--zooplankton-fish. We present a mathematical model of such interactions, which combines a continuous description of the plankton spatio-temporal dynamics and a discrete description of the fish school movement. We show that the fish school can give rise to plankton patches. In turn, fish school walks are shown to depend on phytoplankton growth rate. We show also that the Hurst exponent characterizing the fish school movement in the diffusion approximation depends on phytoplankton growth rate.

Lack of clinical efficacy of additional factor XIII treatment in patients with steroid refractory colitis. The Factor XIII Study Group

Patients with active ulcerative colitis have decreased levels of factor XIII (FXIII) activity, which is important for woundhealing. Recent uncontrolled studies claimed a beneficial effect of Factor XIII on clinical symptoms of ulcerative colitis, in particular intestinal bleeding. The objective of this trial was to evaluate the benefits of additional FXIII treatment in steroid-refractory patients with ulcerative colitis in a prospective, double blind, placebo-controlled study. A total of 28 patients were enrolled between October 1994 and January 1997. Primary objective of this study was the time until cessation of visible intestinal bleeding with 14 days after the start of treatment. Patients were treated for ten days either by i.v. application of FXIII concentrate or by placebo. The analysis of the primary efficacy criterion, cessation of intestinal bleeding, by a planned interim analysis showed no significant differences between the treatment groups (p = 0.8). This resulted in the termination of the study. The same applied to the CAI score. No patient in both treatment groups reached remission according to the colo-/-sigmoidoscopy score. Due to the high number of patients (16 of 28) who had to be excluded from the per-protocol analysis (e.g. changes to the concomitant medication) only the intention-to-treat population was analyzed. Overall the study showed no beneficial effect of additional FXIII treatment on active steroid-refractory ulcerative colitis. These results do not confirm previous open label studies which had reported a significant improvement of clinical symptoms.

Anti-TNF antibody in Crohn's disease--status of information, comments and recommendations of an international working group

The chimeric anti-TNF antibody Remicade (Infliximab) has recently been approved for human use by the FDA and is now available on the market. Since there is considerable interest in this kind of treatment among patients with Crohn's disease, an international working group has summarized the presently available information about efficacy, side effects and possible problems of this treatment. Studies show that Remicade is effective in the treatment of active Crohn's disease, maintaining remission and fistulae. The working group does not see Infliximab as a first-line treatment for Crohn's disease. It may be used in active phase recurrent disease, chronic active disease and fistulae if standard treatment was not successful. For the surveillance special attention has to be given to the unknown malignancy rate of Infliximab. Infusion should be performed in an institution, routinely performing intravenous infusions and a two-hour surveillance of the patients should be guaranteed to recognize anaphylactic reactions or acute side effects. There is presently no information indication that the combination with immunosuppressants might increase risks or side effects of this treatment. Due to the limited information available the working group would prefer to use Remicade in studies only and recommends central collection and documentation of all data on efficacy and side effects for the next year.

Oral budesonide for prevention of postsurgical recurrence in Crohn's disease. The IOIBD Budesonide Study Group

BACKGROUND & AIMS

Prevention of postoperative recurrence after resection for Crohn's disease (CD) would be of great clinical benefit. The efficacy of oral budesonide for prevention of endoscopic recurrence was evaluated in patients undergoing resection for ileal or ileocecal CD.

METHODS

Sixty-three patients received budesonide and 66 received placebo in a double-blind, randomized trial with parallel groups. Ileocolonoscopy, including biopsy, was performed after 3 and 12 months. Indications for surgery were fibrostenosis (78 patients), disease activity (41), and other reasons (10).

RESULTS

The frequency of endoscopic recurrence did not differ between the groups at 3 and 12 months. In patients with disease activity as indication for surgery, the endoscopic recurrence rate at the anastomosis was lower in the budesonide group at 3 months, although not significantly (21% vs. 47%; P = 0.11), and at 12 months (32% vs. 65%; P = 0.047). There was no such difference with respect to fibrostenosis as indication for surgery. No differences in adverse event patterns were found between the two groups.

CONCLUSIONS

Oral budesonide, 6 mg daily, offered no benefit in prevention of endoscopic recurrence after surgery for ileal/ileocecal fibrostenotic CD but decreased the recurrence rate in patients who had undergone surgery for disease activity.

Budesonide prolongs time to relapse in ileal and ileocaecal Crohn's disease. A placebo controlled one year study

BACKGROUND AND AIMS

To evaluate the efficacy and safety of the topical corticosteroid budesonide, given in an oral controlled release formulation for maintenance of remission in patients with ileal and ileocaecal Crohn's disease (CD).

PATIENTS AND METHODS

Out of 176 patients with active CD who had achieved remission (CD activity index score < or = 150) after 10 weeks' treatment with either budesonide or prednisolone, 90 were randomised to continue with once daily treatment of 6 mg budesonide, or 3 mg budesonide or placebo for up to 12 months in a double blind, multicentre trial. Time to symptomatic relapse was calculated using Kaplan-Meier estimates. Morning plasma cortisol was measured at clinic visits and a corticotropin stimulation test was performed after three months of treatment.

RESULTS

Thirty two patients were allocated to the 6 mg budesonide group, 31 to the 3 mg group, and 27 to the placebo group. After three months, 19 per cent of the patients in the 6 mg group had relapsed, compared with 45 per cent in the 3 mg group and 44 per cent in the placebo group (p = 0.047). The corresponding results after 12 months was 59 per cent in the 6 mg budesonide group, 74 per cent in the 3 mg group, and 63 per cent in the placebo group (p = 0.44). The median time to relapse or discontinuation was 258 days in the 6 mg group, 139 days in the 3 mg group, and 92 days in the placebo group (p = 0.021). Mean morning plasma cortisol values increased from entry in all three groups with no statistically significant differences at 12 months. All 13 patients remaining in the placebo group after three months had a normal corticotropin stimulation response, compared with 18 of 23 patients in the 6 mg, and 19 of 21 in the 3 mg budesonide groups (p = 0.14). Acne and moon face were slightly more common in the budesonide groups.

CONCLUSION

6 mg budesonide once daily is significantly more efficacious than placebo in prolonging time to relapse in CD, and causes only minor systemic side effects.

A comparison of budesonide with prednisolone for active Crohn's disease

BACKGROUND

Patients with active Crohn's disease are often treated with corticosteroids, but the treatment has many side effects. Budesonide is a potent, well-absorbed corticosteroid, but because of a high rate of first-pass metabolism in the liver, its systemic bioavailability is low.

METHODS

We conducted a randomized, double-blind, 10-week trial comparing the efficacy and safety of an oral controlled-release form of budesonide with the efficacy and safety of prednisolone in 176 patients with active ileal or ileocecal Crohn's disease (88 patients in each treatment group). The dose of budesonide was 9 mg per day for eight weeks and then 6 mg per day for two weeks. The dose of prednisolone was 40 mg per day for two weeks, after which it was gradually reduced to 5 mg per day during the last week.

RESULTS

At 10 weeks, 53 percent of the patients treated with budesonide were in remission (defined as a score < or = 150 on the Crohn's disease activity index), as compared with 66 percent of those treated with prednisolone (P = 0.12). The mean score on the Crohn's disease activity index decreased from 275 to 175 in the budesonide group and from 279 to 136 in the prednisolone group (P = 0.001). Corticosteroid-associated side effects were significantly less common in the budesonide group (29 vs. 48 patients, P = 0.003). Two patients in the prednisolone group had serious complications (one had intestinal perforation and one an abdominal-wall fistula). The mean morning plasma cortisol concentration was significantly lower in the prednisolone group than in the budesonide group after 4 weeks (P < 0.001) and 8 weeks (P = 0.02) of therapy, but not after 10 weeks.

CONCLUSIONS

Among patients with active Crohn's disease, both controlled-release budesonide and prednisolone are effective in inducing remission. In this trial, prednisolone reduced scores on the Crohn's disease activity index more, whereas with budesonide there were fewer glucocorticoid-associated side effects and less suppression of pituitary-adrenal function.

Laser-assisted removal of a foreign body from the colon

An 81-year-old woman underwent a colonoscopy because of a sigmoiditis poorly responding to conservative therapy. A rod-shaped foreign body found in the sigma proved impossible to remove conventionally. Irradiation with a low laser energy caused the foreign body to break apart, after which its extraction was straightforward. The further clinical course was uncomplicated. In this case a partial sigmoidectomy would have been indicated had the laser-supported extraction not been successful. The authors suggest that a similar procedure could be helpful in the management of foreign bodies in the esophagus.

A randomised controlled trial to evaluate the effects of flumazenil after midazolam premedication in outpatients undergoing colonoscopy

The degree of sedation and amnesia, subjective assessment of awakening and side effects after intravenous injection of 3-4 mg midazolam and 1 mg flumazenil or placebo were studied directly after colonoscopy, and on the first and the eight day. A total of 91 patients were studied; 45 patients were given flumazenil and 46 patients a placebo. Five minutes after injection of the test drugs all 45 patients given flumazenil but only 38 patients given the placebo were alert (p = 0.006). All three response criteria (for sedation, amnesia and subjective assessment of awakening) were fulfilled by 84.4% of the patients given flumazenil and 45.7% of the patients given the placebo (p = 0.0002). Thirty minutes after injection of the test drugs dizziness, nausea, and fatigue were found in 3 patients given flumazenil and in 10 patients given placebo. One day after colonoscopy 9 of 45 patients (20%) given midazolam and flumazenil complained of fatigue and 9 of 46 patients (19.5%) given midazolam and placebo. Eight days (+/- 1 day) later two patients in each group complained of headache, nausea and fatigue. No patient developed phlebitis at the injection site. Flumazenil seems to be a safe and efficient drug for reversing the sedative effect of midazolam, premedication after colonoscopy. However, resedation due to the effects of midazolam may occur. Flumazenil thus permits administration of a higher dose of midazolam without prolongation of the surveillance time. Improved exploitation of time, space and nursing resources is thus possible without jeopardizing patient safety, although caution is necessary since patients may not be fit to resume all normal activities.

Comparison of enteral nutrition and drug treatment in active Crohn's disease. Results of the European Cooperative Crohn's Disease Study. IV

This study compared the effect of enteral nutrition as the sole therapy of active Crohn's disease with drug treatment. Patients with active Crohn's disease (Crohn's Disease Activity Index greater than 200) were randomized to receive either enteral nutrition with a liquid oligopeptide diet (n = 55) or a combination of 6-methylprednisolone, 48 mg daily, subsequently tapered, and sulfasalazine, 3 g daily (n = 52). The two groups were not different with respect to age, sex, body weight, location of disease, or treatment before the study. The severity of disease was similar at the beginning of the study in both groups [Crohn's Disease Activity Index (mean +/- SEM), 323 +/- 12 vs. 316 +/- 11]. Remission was defined as a decrease of the initial Crohn's Disease Activity Index by 40% or at least 100 points. Twenty-nine patients in the diet group and 41 patients in the drug group reached remission within 6 weeks of therapy (chi 2 test, P less than 0.01). The median elapsed time to remission was 30.7 days in the diet group compared with 8.2 days in the drug group (Mantel Cox, P less than 0.01). To determine whether one of these treatments was more beneficial for a subgroup of patients, the effectiveness of both treatments was analyzed separately in patients with very severe disease (initial Crohn's Disease Activity Index greater than 300) and less severe disease (initial Crohn's Disease Activity Index less than 300), and in patients with different disease location. However, no influence of initial disease activity or disease location on the effect of either treatment could be shown. These data show that enteral nutrition is less effective than a combination of 6-methylprednisolone and sulfasalazine in treating active Crohn's disease.

Evaluation of the Crohn's Disease Activity Index (CDAI) and the Dutch Index for severity and activity of Crohn's disease. An analysis of the data from the European Cooperative Crohn's Disease Study

In the European Cooperative Crohn's Disease Study a general documentation of clinical and laboratory data was made at the entry into the study in 452 patients. These patients were in different states of their disease from quiescent to very active. In all patients the Crohn's Disease Activity Index of Best (CDAI) and the Dutch Index of van Hees was calculated. Three gastroenterologists did a global clinical rating and a separate laboratory rating without knowledge of the indices. The ratings were then correlated with the indices in the individual patients. The clinical rating correlated well with the CDAI (r = 0.88) and less with the Dutch Index (r = 0.672). On the other hand the laboratory rating showed a better correlation with the Dutch Index (r = 0.742) than with the CDAI (r = 0.573). This demonstrates that the CDAI preferably is an estimate of the clinical severity of the disease and not of the activity of inflammation. Vice versa the Dutch Index is mainly reflecting the activity of the inflammatory process.

Feasibility and effectiveness of a defined-formula diet regimen in treating active Crohn's disease. European Cooperative Crohn's Disease Study III

In a randomized multicenter trial the efficacy of treatment of active Crohn's disease by means of a liquid defined formula diet (DFD) was tested and compared with a combination of 6-methyl-prednisolone and sulfasalazine. A total of 95 patients participated in the study. By the end of 6 weeks, among 44 patients randomized to drug treatment, 32 showed improvement of the Crohn's disease activity index (CDAI) as compared with 21 of 51 patients receiving oral DFD (p less than 0.05). The proportion of withdrawals in the DFD group (29 of 51) was sevenfold higher than in the drug group (4 of 44). However, most patients (20 of 29) receiving DFD withdrew because of the unpalatability of the liquid diet. Analysis of patients in each group who finished the study showed equal effectiveness of DFD and the drug regimen. In these subsets of patients the CDAI decreased from 280.8 +/- 90.6 to 151.7 +/- 86.5 (DFD) and from 263.7 +/- 86.3 to 129.3 +/- 63.7 (drug), respectively. Improvement of inflammation factors was similar in both groups at the end of the study, although improvement was delayed in the DFD group. In conclusion, our data show a superiority of the drug combination over DFD in the treatment of Crohn's disease under the conditions of this trial. The results do suggest, however, that DFD offers a therapeutic alternative to prednisolone and sulfasalazine in a subgroup of patients, which has to be closer characterized in further studies.