p-octiphenyl beta-barrels with ion channel and esterase activity.

Design, synthesis, and esterase and ion channel activity of a novel barrel-stave supramolecule with hydrophobic exterior and histidine-rich interior are reported. Voltage-dependent binding of pyrenyl-8-oxy-1,3,6-trisulfonates by histidines within p-octiphenyl beta-barrels (and not monomers) via ionic (and not hydrophobic) interactions (K(D), K(I), K(M) < 1 microM) is the basis for superb esterolytic proficiency up to (k(cat)/K(M))/k(uncat) = 9.6 x 10(5) in water and bilayer membranes. The conductance of labile ion channels formed in planar bilayer membranes is shown to be reduced by 8-hydroxypyrene-1,3,6-trisulfonate on the single- and multichannel level. [reaction: see text]

Rigid-rod beta-barrels as lipocalin models: probing confined space by carotenoid encapsulation.

Herein, we describe the design, synthesis, structure, and function of synthetic, supramolecular beta-barrel models. Assembly of octi(p-phenylene)s with complementary -Lys-Leu-Lys-NH2 and Glu-Leu-Glu-NH2 side chains yielded water-soluble rigid-rod beta-barrels of precise length and with flexible diameter. A hydrophobic interior was evidenced by guest encapsulation. Host-guest complexes with planarized, monomeric beta-carotene within tetrameric rigid-rod beta-barrels, and disc micellar astaxanthin J-aggregates surrounded by about dodecameric rigid-rod "bicycle tires" were prepared from mixed micelles by dialytic detergent removal. The significance of these findings for future bioorganic chemistry in confined, intratoroidal space is discussed in comparison with pertinent biological examples.

Neutrophil-elastase in chronic inflammatory bowel disease: a marker of disease activity?

BACKGROUND/AIMS: Neutrophil elastase is a proteinase which exists in granulocytes and plays an important role in the pathogenesis of inflammatory disorders. In inflammatory bowel disease there is a leukocyte infiltration of the bowel mucosa. The purpose of this study was to examine whether plasma elastase represents a reliable laboratory marker for establishing the activity of chronic inflammatory bowel disease. METHODOLOGY: We measured plasma elastase concentrations in 61 patients suffering from either Crohn's disease or ulcerative colitis and compared these data with other clinical and laboratory findings and with elastase concentrations in 40 healthy controls. The sensitivity and specificity of the elastase values in chronic IBD were calculated with the use of concomitant measurements of CRP and ESR. RESULTS: Plasma levels were found to be significantly higher in patients (49 micrograms/l) compared with healthy controls (23 micrograms/l). Patients with active disease had higher plasma levels than patients in remission. In general, the sensitivity of elastase to detect active inflammatory bowel disease was about 60%; the specificity was 65%. For patients in remission, the sensitivity was higher than 80%. However, there was a wide range of overlapping values between chronic inactive patients and those with moderately active disease. CONCLUSIONS: We conclude that plasma elastase is a useful independent marker of disease activity in inflammatory bowel disease. Especially for identifying patients in remission, the measurements of elastase seem to be more suitable than other parameters of inflammation, like CRP or ESR.

Immunoglobulins and IgG subclasses in patients with inflammatory bowel disease.

BACKGROUND/AIMS: Serum immunoglobulin levels and distribution are altered in patients with inflammatory bowel disease (IBD). The purpose of this study is to examine the value of serum concentration of IgG subclasses for the diagnosis and evaluation of disease activity of IBD and to assess possible differences in the immunoglobulin changes between patients with Crohn's disease (CD) and ulcerative colitis (UC). METHODOLOGY: We measured serum IgG and IgG subclasses concentrations as well as IgA, IgM, ESR, CRP, elastase levels and granulocyte count of 96 patients with chronic IBD (69 with CD and 27 with UC) with various levels of disease activity. RESULTS: The total IgG levels in patients with UC were significantly increased, for both active and inactive disease, compared to those of patients with CD. The IgG1 concentration in patients with UC (7+/-0.77 mg/ml) was significantly higher than in patients with CD (5.6+/-0.61 mg/ml) (p<0.02). The IgG2 levels in CD were significantly higher than those of UC (4.6+/-0.64 vs. 3.8+/-0.57 mg/ml) (p<0.05). The IgG4 levels of UC patients were significantly higher than those of the CD patients (0.39+/-0.06 vs. 0.29+/-0.05 mg/ml) (p<0.05). No significant differences were found in the serum concentrations of IgG3, IgA and IgM between the two groups. There was a negative correlation between the various indices of disease activity and the concentration of IgG3 in patients with UC (p<0.01), and a positive correlation in patients with CD for IgG1 (p<0.001), IgG2 (p<0.001) and IgA (p<0.01). CONCLUSIONS: In IBD some of the IgG immunoglobulin subclass concentration changes correlate, positively or negatively, with disease activity and therefore could be used as additional markers of it. However, serum immunoglobulin levels cannot be used to differentiate between UC and CD.

Magaldrate stimulates endogenous prostaglandin E2 synthesis in human gastric mucosa in vitro and in vivo.

BACKGROUND/AIMS: Prostaglandin E2 (PGE2) plays an important role in the inhibition of gastric acid production and exerts cytoprotective action. The in vitro and in vivo effect of magaldrate, an aluminum containing antacid, on PGE2 synthesis in the gastric mucosa was investigated. METHODOLOGY: In the first part of the study, magaldrate was added to a suspension of isolated gastric mucosal cells. In the second part, the antacid gel was applied to the gastric mucosa during gastroscopy and biopsies were taken from the same site 5 and 10 min later. RESULTS: The antacid significantly stimulated PGE2 release from the suspension of isolated gastric cells in vitro. The biopsies obtained after the application of magaldrate showed an increased PGE2 production compared to specimens obtained before. CONCLUSIONS: The data suggest that in addition to its neutralizing capacity as an antacid, magaldrate contributes to the cytoprotective activity of the mucosa by stimulating endogenous PGE2 synthesis.

Calcium modulates the synthesis of prostaglandin E2 in isolated colonic mucosal cells.

BACKGROUND/AIMS: The effect of calcium on colonic prostaglandin E2 synthesis was investigated in 26 healthy volunteers. MATERIAL AND METHODS: Biopsy specimens were obtained by colonoscopy and the mucosal cells were separated biochemically. The cells were incubated in EDTA or CaCl2 containing media for 15 and 30 minutes. RESULTS: The PGE2 synthesis was significantly (p < 0.001) diminished in the calcium free suspension (EDTA) compared to the CaCl2 containing suspension. To increase intracellular Ca2+ concentration, calcium ionophore A 23187 was added for the last 15 minutes. It significantly stimulated the prostaglandin production. In addition, the calcium channel blocker verapamil did not alter the PGE2 synthesis, whereas trifluoperazine, a calmodulin inhibitor, markedly decreased the production rate. CONCLUSION: Calcium is an important stimulus of prostaglandin synthesis and inhibition of calmodulin by trifluoperazine decreases the arachidonic metabolism. In these regards, colonic tissue shares features with other tissues. However, in contrast to smooth or cardiac muscle, intracellular calcium concentration in colonic mucosa is not affected by verapamil, indicating that colonic calcium channels have a different affinity to this drug.

Evaluation of predictors of weaning from mechanical ventilation in pediatric patients.

Objective criteria for ending mechanical ventilation have not been established for infants and children. A recent study in adult patients developed two new indexes, the Rapid Shallow Breathing Index (RSB) and the CROP Index for predicting success or failure of extubation. We decided to evaluate the applicability of these indices to intubated, mechanically ventilated pediatric patients. For this evaluation the indices were adapted to the physiology of infants and children. A pneumotachograph was used to measure spontaneous tidal volume, respiratory rate and dynamic compliance. The tidal volume and the dynamic compliance were corrected for the patient's body weight. Based on the data collected a cutoff value for each index was determined. Of 47 sets of patient data, 38 (81%) were collected during successful extubations, 9 (19%) during failed extubations. A modified CROP index value of > or = 0.1 ml x mmHg/bpm/kg and a modified RSB index value of < or = 11 bpm/mlkg were identified as predictive of successful extubation. The modified CROP cutoff value produced a sensitivity and specificity of 1.0; respective values for the modified RSB cutoff value are 0.79 and 0.78. Cutoff values of > or = 0.1 and < or = 11 for the modified CROP index and RSB index, respectively, appear to be predictive of successful extubation in the pediatric population. Our data identifies the modified CROP index as a superior discriminator between successful and unsuccessful extubation.

Alteration of prostaglandin E2 and leukotriene B4 synthesis in chronic inflammatory bowel disease.

BACKGROUND: Eicosanoid mediators play an important role in the pathogenesis of chronic inflammatory bowel disease. MATERIALS AND METHODS: The synthesis of prostaglandin E2 and leukotriene B4 in biopsied colonic specimens from patients with inflammatory bowel disease was compared with that from healthy controls. In contrast to surgical resection, biopsy by colonoscopy enabled patients with milder disease to be investigated. RESULTS: In subjects with Crohn's disease or ulcerative colitis, the synthesis of PGE2 was significantly (p < 0.05) increased, whereas synthesis of LTB4 remained unaltered. In addition, no differences in PGE2 and LTB4 production were found in different age groups or sex. CONCLUSION: We conclude that prostaglandin E2, compared to leukotriene B4, is the dominant eicosanoid in moderate inflammatory bowel disease.

Measurement of body fat in young and elderly women: comparison between a four-compartment model and widely used reference methods.

Body composition was measured in twenty young females aged 19-27 years and eighteen elderly females, aged 65-78 years by densitometry (underwater weighing), deuterium oxide dilution and dual-energy X-ray absorptiometry (DXA). From body weight, bone-mineral content, total body water and body density, percentage body fat (BF%) was calculated using a four-compartment model. BF% obtained by this four-compartment model was regarded as a reference method and BF% obtained by the single methods were compared with this value. Differences in BF% from the four-compartment model minus the single methods were 2.1 (SD 1.2) for densitometry, 3.1 (SD 1.8) for DXA and -0.6 (SD 0.9) BF% for deuterium oxide dilution in the young women. In the elderly women these values were -0.6 (SD 2.3), 5.3 (SD 3.8) and 0.7 (SD 2.2) BF%. When a three-compartment model (calculated from body density and total body water) was compared with the four-compartment model, the bias was 0.4 (SD 0.3) BF% in the young and 0.0 (SD 0.3) BF% in the elderly women. From the mineral and water fractions in the fat-free mass the true density of the fat-free mass was calculated as 1.1070 (SD 0.0047) kg/l in the young females and 1.0970 (SD 0.0088) kg/l in the elderly women (P < 0.001). This study shows that the single methods have considerable mean and individual biases compared with the four-compartment model, but that a three-compartment model calculated from density and total body water offers an acceptable alternative. The difference in calculated density of the fat-free mass between the young and the elderly women shows the need to adapt Siri's formula for specific groups.

Increased prostaglandin E2 and leukotriene B4 synthesis in isolated colonic mucosal cells in inflammatory bowel disease. a preliminary report.

The synthesis of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) in colonic mucosal cells was investigated in 7 patients and 10 controls. Biopsies obtained from the descending colon were isolated biochemically by a special technique and the suspension of isolated colonic cells was incubated during 45 min. Compared with healthy subjects, patients with an inflammatory bowel disease showed a significantly increased PGE2 production. The LTB4 synthesis was enhanced as well, but this change was not statistical. We conclude that PGE2 is the dominant eicosanoid during less severe inflammatory bowel disease. Age and gender did not influence PGE2 or LTB4 synthesis.

Inspiratory pressure/maximal inspiratory pressure: does it predict successful extubation in critically ill infants and children?

OBJECTIVE: To evaluate the accuracy of the initial negative inspiratory pressure (PI) to maximal negative inspiratory pressure (PImax) ratio in predicting extubation outcome for intubated infants and children. DESIGN: A prospective study. SETTING: Pediatric intensive care unit. PATIENTS: A sample of 50 stable intubated pediatric patients who were judged clinically ready for extubation. METHODS: Using a one-way valve, PI and PImax were measured in all patients, after which the < or = ratio PI/PImax was calculated and its accuracy in predicting extubation outcome evaluated. MEASUREMENTS AND RESULTS: A total of 39 patients (78%) were successfully extubated and 11 patients (22%) were not. The mean PI/PImax ratio was not significantly different between extubation successes (0.36 +/- 0.14) and failures (0.45 +/- 0.1) (P > 0.05). The cut-off value of 0.3 for PI/PImax identified in adult patients did not discriminate between extubation success and failure in children. Furthermore, a discriminatory cut-off value other than 0.3 could not be identified for infants and children. CONCLUSION: The PI/PImax ratio cannot be used to predict extubation outcome in pediatric patients. Indices that predict extubation outcome in adults should not be extrapolated to infants and children before testing and validation.

The effect of 5-aminosalicylate and para-aminosalicylate on the synthesis of prostaglandin E2 and leukotriene B4 in isolated colonic mucosal cells.

The effect of 5-aminosalicylate (5-ASA) and para-aminosalicylate (PAS) on the synthesis of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) was studied in 24 healthy volunteers. Both drugs are successfully used in the treatment of chronic inflammatory bowel disease, but the biochemical pathway of their anti-inflammatory action is still unknown. Biopsies were taken from the descending colon and were isolated biochemically. 5-ASA, PAS and a control were added to the suspension of isolated colonic mucosal cells and incubated over 0-45 min. Both 5-ASA and PAS did not alter the PGE2 production but, compared with PAS and the control, 5-ASA decreased the LTB4 synthesis in a dose-related fashion. As a result, the LTB4/PGE2 ratio was significantly diminished by 10(-4) mol/l 5-ASA. These findings are consistent with those of other authors, indicating that 5-ASA, at least in part, modulates the colonic eicosanoid synthesis. In contrast, PAS did not influence the mucosal production of PGE2 and LTB4 and therefore must exert some other biochemical action in order to explain its therapeutic effects in the treatment of Crohn's disease or ulcerative colitis.

Decreased gastric prostaglandin E2 synthesis in patients with gastric ulcers and in smokers.

BACKGROUND/AIMS: Prostaglandin inhibits gastric acid secretion and exerts protective action on the mucosa of the stomach. We studied the synthesis of prostaglandin E2 (PGE2) to determine the role of PGE2 in peptic ulcer disease. MATERIALS AND METHODS: Mucosal biopsies from 22 persons were obtained and incubated. PGE2 was then determined by radioimmunoassay. RESULTS: Compared to healthy subjects, patients with gastric ulcers or gastritis show diminished accumulation of PGE2 in the incubation medium. Other factors like age, gender, and alcohol consumption were also investigated, however, they do not influence endogenous prostaglandin production. In contrast, PGE2 synthesis was found to be decreased in smokers. CONCLUSIONS: Our data indicates a deficiency in endogenous PGE2 synthesis as one cause of gastric ulcerations and offer an explanation of the higher incidence of gastric ulcer disease in subjects with nicotine abuse.

Arachidonic acid metabolism and intracellular calcium concentration in inflammatory bowel disease.

OBJECTIVE: To study the alteration of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) synthesis and intracellular Ca2+ concentration in chronic inflammatory bowel disease, and to ascertain the effect of anti-inflammatory drugs and other mediators on eicosanoid synthesis and Ca2+ concentration. METHODS: Biopsies taken from the descending colon were isolated biochemically. The suspension of isolated mucosal cells was incubated for 15 min in the presence and absence of arachidonic acid and the Ca2+ ionophore A23187. PGE2 and LTB4 concentrations in the incubation medium were measured by radioimmunoassay, and the intracellular Ca2+ concentration was determined using fura-2. We studied 107 subjects. In addition, the effects of bradykinin, endothelin, cyclosporin A and PGE2 on intracellular Ca2+ concentration were determined in 25 individuals. RESULTS: Untreated patients with active inflammatory bowel disease showed a significant increase in LTB4 synthesis compared with healthy controls. However, in patients receiving steroids, sulphasalazine or 5-aminosalicylic acid, both LTB4 and PGE2 synthesis were markedly decreased. When arachidonic acid was added to the cell suspension, it significantly stimulated LTB4 synthesis, especially in patients with active disease. Patients with active Crohn's disease or ulcerative colitis had moderately higher Ca2+ levels than healthy controls. However, there was a significant decrease in intracellular Ca2+ concentration in patients with quiescent disease who were receiving maintenance therapy. CONCLUSION: We suggest that increased LTB4 synthesis and elevated intracellular Ca2+ concentrations contribute to the pathophysiology of inflammatory bowel disease. Drugs effective in the treatment of these diseases may exert their pharmacological action by normalizing these pathological findings.

The risks of metastases from shunting in children with primary central nervous system tumors.

The authors reviewed the hospital charts of 415 pediatric patients treated for benign or malignant primary brain tumors over the past 20 years at the Children's Hospital Medical Center, Seattle. Patients' ages ranged from the neonatal period to 18 years. A shunt was placed in 152 patients (37%), 45 before and 94 after surgery. Confirmation of extraneural metastases was based on clinical and diagnostic examination. Factors analyzed as possibly influencing the occurrence of extraneural metastases were: 1) the shunt: type, valve, location, filter, and revisions; 2) extent of resection; 3) pathology; and 4) treatment regimen. Eight of the 415 patients developed extraneural metastases during life. All eight patients had a medulloblastoma (cerebellar primitive neuroectodermal tumor). These eight patients were separated into Group A (without a shunt) and Group B (with a shunt). In Group A (five patients), the mean interval from primary diagnosis to metastasis was 15 months. Two children had gross total resection of the tumor. The predominant location of metastases in Group A was: bone (two cases); cervical lymph nodes (one); lung/bone (one); and retroperitoneal pelvic mass (one). Three Group A patients had a simultaneous central nervous system (CNS) recurrence. Of the three Group B patients, two had a ventriculoperitoneal (VP) shunt and one a ventriculoatrial (VA) shunt; all were placed postoperatively. One Group B patient had a simultaneous CNS recurrence. No shunt revisions were performed in these three patients. The mean time from primary diagnosis to metastasis was 25 months. One patient had a total tumor resection. The predominant location of metastases was bone (one case), retroperitoneal pelvic mass (one), and abdominal cavity with ascites (one case). Only one patient in the entire series had a filter placed; this resulted in shunt obstruction and was removed 1 month following placement. It is concluded that cerebrospinal fluid shunts, regardless of type, location, revision rate, or filter insertion, do not predispose pediatric patients with brain tumors to develop extraneural metastases. A diagnosis of shunt-related metastases should be based on the development of intra-abdominal (VP shunt) or pulmonary (VA shunt) dissemination primarily with or without additional sites. The diagnosis of medulloblastoma is an important factor related to metastasis occurrence while the extent of resection and postoperative therapy are not influential.

[Weakness, bone pain]. / Schwäche, Knochenschmerzen.

A 57-year-old man complains of a reduced exercise tolerance and bone pain for years. There is a past medical history of hyperuricemia and anemia of unknown etiology. In a routine examination a leukocytosis of 64,000 per ml, increased number of thrombocytes and an elevated level of lactic dehydrogenase is found. The suspected diagnosis of myeloproliferative disorder, in the present case of chronic myelogenous leukemia, is confirmed by a diminished neutrophil alkaline phosphatase activity, bone marrow biopsy and the demonstration of the Ph1 (Philadelphia) chromosome. Magnetic resonance imaging reveals an infiltration of the bone marrow. After the initial treatment with busulfan the white cell count is lowered.