Visualization of Surfactants on Nanostructured Palladium Clusters by a Combination of STM and High-Resolution TEM.

Scanning tunneling microscopy (STM) and high-resolution transmission electron microscopy (TEM) have been used to determine the dimensions of a series of palladium clusters stabilized by tetraalkylammonium salts. Electrochemically prepared colloids were used in which the average diameter of the inner metal core was varied between 2 and 4 nanometers, and the size of the ammonium ions was adjusted in the series (+)N(n-C(4)H(9))(4) < (+)N(n-C(8)H(17))(4) < (+)N(n-C(18)H(37))(4). The difference between the mean diameter determined by STM and that measured by TEM allows the determination of the thickness of the protective surfactant layer. On the basis of these studies, a model of the geometric properties of ammonium-stabilized palladium clusters has been proposed. Suggestions for the mechanism of the STM imaging process are also made.

Combined preoperative chemotherapy and radiotherapy in patients with locally advanced esophageal cancer. Interim analysis of a phase II trial.

PURPOSE: The prognosis of patients with locally advanced esophageal cancer (LAEC) remains poor when treated with local modalities. An intensive preoperative program with chemoradiotherapy was used to evaluate the curative resection rate, pathologic response, and survival of patients with LAEC. PATIENTS AND METHODS: Ninety patients with LAEC were treated preoperatively with chemotherapy (three courses of fluorouracil, leucovorin, etoposide, and cisplatin [FLEP]) followed by concurrent chemoradiotherapy (one course of cisplatin plus etoposide in combination with 40 Gy of radiation). Transthoracic esophagectomy was performed 4 weeks after the end of radiation. RESULTS: Seventy-two patients were included in this evaluation. Forty-four (61%) underwent a complete tumor resection, and 16 (22%) had no tumor in the resected specimen (pathologic complete response [PCR]). The operative mortality rate was 15%. At a median follow-up time of 22 months (range, 12 to 41), the median survival duration of all 72 patients was 17 months (range, 1 to 41+). The calculated survival rates at 3 years were 33%, 42%, and 68% for all patients, patients after complete resection, and patients with PCR, respectively. CONCLUSION: This combined treatment modality is active in LAEC, with a PCR in 33% of the patients undergoing surgery. The results appear improved compared with those reported with surgery alone, by approximately doubling the 3-year survival rate. The high efficacy of preoperative chemoradiation warrants evaluation of the role of surgery in LAEC.

Value of an extended monoethylglycinexylidide formation test and other dynamic liver function tests in liver transplant donors.

Measuring monoethylglycinexylidide (MEGX) formation after intravenous administration of lidocaine in potential organ donors (MEGX test) has been advocated as a useful test to select donor livers for transplantation, but some groups have demonstrated a low test efficacy. We, therefore, investigated the value of an extended MEGX formation test and the value of other dynamic liver function tests, in selecting suitable human donor livers. In 51 human multi-organ donors, we measured elimination of galactose, indocyanine green, and lidocaine, as well as formation of MEGX, at 15, 30, and 60 min after administration of the test substances. In the early postoperative period, the function of the transplanted liver was then classified as good or poor, as defined by a prothrombin time above or below 65% by day 4 and fibrinogen concentration above or below 300 mg/dl by day 7. Donor characteristics and preservation modalities were very similar between the two groups. Galactose, indocyanine green, and lidocaine metabolism failed to predict good or poor graft function in the early postoperative period. MEGX serum concentrations, however, were significantly higher in the group of donors whose organs functioned well in the recipients, as compared with donors whose organs functioned poorly in the recipients. This was true for MEGX concentrations at 15 min (117+/-9 vs. 90+/-9 ng/ml; P=0.03), 30 min (108+/-8 vs. 86+/-8 ng/ml; P=0.04), and 60 min (100+/-6 vs. 73+/-5 ng/ml; P=0.006). Extending the MEGX formation test from 15 to 60 min improved test efficacy. Maximal MEGX concentration in 9 or up to 12 consecutive blood samples, drawn between 3 and 120 min after lidocaine infusion, was also significantly higher in donors whose organs functioned well, than in donors whose organs functioned poorly (129+/-10 vs. 101+/-10 ng/ml; P=0.03). Although the groups with good and poor organ function differed significantly with respect to their MEGX serum concentrations, and although efficacy of the MEGX test was improved by extending the test from 15 to 60 min, the overlap in individual MEGX serum concentrations was still so wide that it is virtually impossible to predict early graft function only on the basis of the MEGX test in the donor. Therefore, the MEGX test, although of potential scientific interest, does not predict early graft function with an accuracy necessary for clinical use.

[Postprandial serum bile acid level and 75SeHCAT retention in diagnosis of bile acid malabsorption syndrome. A comparative study]. / Postprandiale Serumgallensäurenspiegel und 75SeHCAT-Retention in der Diagnostik der Gallensäurenverlustsyndrome. Eine vergleichende Studie.

Postprandial serum bile acids (expressed as integrated bile acid response [IR]) after a standardized test meal were compared with 75SeHCAT retention, measured in a whole body counter, in healthy controls (n = 20), in 44 patients with ileal disease or resection and in 23 patients with colitis without ileal involvement. In the controls the IR after 180 min was 736 +/- 186 mumol x min x 1(-1) (mean +/- standard deviation), the 75SeHCAT retention 31 +/- 9%. 80% of the patients with ileal disease or resection had a decreased 75SeHCAT retention, indicating bile acid malabsorption, but only 59% had a diminished IR. One of the 23 patients with colitis and radiologically normal ileum had a decreased 75SeHCAT retention but a normal IR, reflecting a dysfunction of the morphologically normal ileum. The characteristics of the two tests are: 75SeHCAT retention test: sensitivity 80%, specificity 98%, accuracy 89%; postprandial serum bile acids: sensitivity 64%, specificity 74%, accuracy 69%. With respect to chronic inflammatory bowel disease the positive predictive value of the 75SeHCAT retention test is 1.0%, for postprandial serum bile acids 0.1%, whereas the negative predictive values amount to 99% for both tests. Thus 75SeHCAT retention is more reliable in detecting bile acid malabsorption than the determination of postprandial serum bile acids, although both tests are not usefull for screening the population for ileal disease.

[Increased plasma endothelin concentrations in patients after liver transplantation and in liver cirrhosis]. / Erhöhte Plasma-Endothelin-Konzentrationen bei Patienten nach Lebertransplantation und bei Leberzirrhose.

Endothelin, one of the most potent vasoconstrictors known today, is released by the vascular endothelium. Patients after liver transplantation and patients with liver cirrhosis show significantly higher plasma endothelin concentrations and significantly reduced results in the quantitative liver function tests (ICG-HL, GEC, Lidocaine-HL, MEGX) compared with healthy control persons. The plasma endothelin concentrations were better correlated with the more liver bloodflow dependent function tests (ICG-HL, Lidocaine-HL) than with the more metabolic-capacity dependent function tests (GEC, MEGX). As cyclosporine A in vitro can increase the liberation of endothelin, we conclude that in patients after liver transplantation an endothelin mediated cyclosporine induced hepatotoxicity might be the reason for the demonstrated association.

The role of bile acids in colonic carcinogenesis.

Several line of evidence suggest that bile acids may be implicated in the pathogenesis of colonic cancer. A high consumption of fat and animal protein and a low dietary intake of fiber have been shown to be related to the incidence of colonic cancer. From these epidemiologic observations the hypothesis was proposed that the correlation between diet and colon cancer might be explained by the involvement of bile acids. Populations at a high risk of developing cancer were shown to have an increased excretion both of total and bacterially modified bile acids in their feces. Animal studies demonstrated a cocarcinogenic effect of bile acids and experimental diets containing large amounts of fat did not only induce an increased bile acid excretion but also an enhanced tumor formation in the colon. Furthermore, microbial in vitro tests showed a comutagenic activity of secondary bile acids. However, case control studies comparing the fecal bile acid excretion pattern in colonic cancer patients and control subjects failed to show such a clear relationship, which might be explained by rather similar dietary habits within one population and individual differences in sensitivity to environmental factors contributing to the tumor development. Cholecystectomy, leading to an increased exposure of bile acids to the intestinal microflora, has been suggested as a predisposing factor for the development of colonic cancer, but the results of experimental and epidemiologic studies so far are rather inconsistent.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastroenterologic manifestations of mastocytosis.

Mastocytosis as a rare disease is usually diagnosed by dermatologists because of urticaria pigmentosa as one of the leading signs. If the triad of urticaria pigmentosa, flush and diarrhea is present diagnosis is easily made. However, urticaria pigmentosa and flush may be less dominant or even absent and gastrointestinal signs may render diagnosis more difficult. Therefore, this review is thought to describe clinical manifestations of mastocytosis from the gastroenterologist's point of view. In addition, on the grounds of a recent classification of mastocytosis practical diagnostic procedures as well as therapeutic approaches are discussed.

[Effects of antirheumatics on the glycosaminoglycan distribution pattern of fetal tibia cultured in vitro]. / Einfluss einiger Antirheumatika auf das Glykosaminoglykan-Verteilungsmuster in vitro gezüchteter fetaler Tibiaanlagen.

The glycosaminoglycan (GAG) distribution pattern of murine fetal tibiae cultured for 6 days in vitro was determined and the effects of drugs on the growth of the tibia explants in vitro, on their total GAG content and on their GAG distribution pattern were studied. The explants contained chondroitin-4-sulfate and chondroitin-6-sulfate in a relation of about 4:1; hyaluronic acid was not detected. During the incubation period of 6 days in vitro a mean increase in size of 47% and of the total GAG content of about 80-90% was observed; the GAG distribution pattern was practically unchanged. Incubation of the explants in a medium without ascorbic acid by contrast to a medium containing ascorbic acid (5 and 50 micrograms/ml) lead to a reduction of growth and total GAG content. The nonsteroidal antiphlogistic drugs phenylbutazone (20 and 200 micrograms/ml), ibuprofen (25 and 200 micrograms/ml) and alclofenac (25 and 400 micrograms/ml) effected a concentration dependent decrease of the growth and of the GAG content of the explants mainly due to a reduction of chondroitin-4-sulfate. Prednisolone (10 micrograms/ml) caused a significant increase of the GAG content of the explants leaving their GAG distribution pattern nearly unchanged. Aurothioglucose (400 micrograms/ml) induced a reduction of the growth and of the GAG content of the explants without altering the GAG distribution. Under low concentrations of Na-pentosanpolysulfate (5 micrograms/ml) an increase in growth and in the GAG content by a nearly unaltered GAG distribution pattern was observed, high concentrations (200 micrograms/ml), however, caused a reduction of growth and of the GAG content.