Novel computed tomography-based tools reliably quantify plant reproductive investment.

The flower is a bisexual reproductive unit where both genders compete for resources. Counting pollen and ovules in flowers is essential to understand how much is invested in each gender. Classical methods to count very numerous pollen grains and ovules are inefficient when pollen grains are tightly aggregated, and when fertilization rates of ovules are unknown. In this study we have therefore developed novel counting techniques based on computed tomography. In order to demonstrate the potential of our methods in very difficult cases, we counted pollen and ovules across inflorescences of deceptive and rewarding species of European orchids, which possess both very large numbers of pollen grains (tightly aggregated) and ovules. Pollen counts did not significantly vary across inflorescences and pollination strategies, whereas deceptive flowers had significantly more ovules than rewarding flowers. The within-inflorescence variance of pollen-to-ovule ratios in rewarding flowers was four times higher than in deceptive flowers, possibly demonstrating differences in the constraints acting on both pollination strategies. We demonstrate the inaccuracies and limitations of previously established methods, and the broad applicability of our new techniques: they allow measurement of reproductive investment without restriction on object number or aggregation, and without specimen destruction.

Indwelling peritoneal catheters in patients with cirrhosis and refractory ascites.

BACKGROUND: The prevalence of spontaneous bacterial peritonitis (SBP) in hospitalised cirrhotics with ascites is 10-30%. Treatment for refractory ascites includes paracenteses, transjugular intrahepatic portosystemic shunt or drain placement; the latter is discouraged due to a perceived infection risk. AIM: This study aimed to evaluate the risk of bacterial peritonitis (BP) with peritoneal drains in patients with Child-Pugh class B or C cirrhosis and determine their impact on survival. METHODS: We conducted a retrospective review of end-stage liver disease (ESLD) patients with non-malignant, refractory ascites who had peritoneal drains placed for ≥3 days at Loyola University between 1999 and 2009. Cell counts were performed at drain placement and within 72 h. BP was defined as ascitic polymorphonuclear neutrophils >250/mm(3) . Univariate analysis assessed the association between demographics, laboratory markers and development of BP. Kaplan-Meier curve estimates by infection were constructed and survival distributions were compared using log-rank statistic. RESULTS: There were 227 drain placements during the study period. Twenty-two per cent were diagnosed with BP (12% had SBP at drain placement; 10% developed BP within 72 h). There was no association between BP and baseline characteristics. Patients who developed BP within 72 h of drain placement had 50% mortality at 5 months compared with 50 months in those without infection (log-rank P ≤ 0.003). CONCLUSION: In ESLD patients who received an indwelling peritoneal catheter, there was 10% risk of developing BP and significant mortality increase. Though placing drains is not the mainstay of treatment for refractory ascites, we confirm the theoretical adverse risk of peritoneal drains on infection and survival in cirrhotics.

π-Complexation in nickel-catalyzed cross-coupling reactions.

The kinetic isotope effect (KIE) is used to experimentally elucidate the first irreversible step in oxidative addition reactions of a zerovalent nickel catalyst to a set of haloarene substrates. Halogenated o-methylbenzene, dimethoxybenzene, and thiophene derivatives undergo intramolecular oxidative addition through irreversible π-complexation. Density functional theory computations at the B3LYP-D3/TZ2P-LANL2TZ(f)-LANL08d level predict η(2)-bound π-complexes are generally stable relative to a solvated catalyst plus free substrate and that ring-walking of the Ni(0) catalyst and intramolecular oxidative addition are facile in these intermediates.

Palladium-Mediated Surface-Initiated Kumada Catalyst Polycondensation: A Facile Route Towards Oriented Conjugated Polymers.

Palladium-mediated surface-initiated Kumada catalyst transfer polycondensation is used to generate poly(3-methyl thiophene) films with controlled thickness up to 100 nm. The palladium initiator density is measured using cyclic voltammetry and a ferrocene-capping agent, where the surface density is found to be 55% (1.1 × 10(14) molecules per cm(2)). UV-Vis spectroscopy and AFM show increased aggregation in palladium-initiated films due to the higher grafting density of palladium initiators on the surface. The anisotropy of the P3MT films is determined using polarized UV-Vis spectroscopy, which indicates a degree of orientation perpendicular to the substrate. Evidence that palladium can maintain π-complexation even at elevated temperatures, is also shown through the exclusive intramolecular coupling of both a phenyl and thiophene-based magnesium bromide with different dihaloarenes.

Surface-confined nickel mediated cross-coupling reactions: characterization of initiator environment in Kumada catalyst-transfer polycondensation.

Kumada catalyst-transfer polycondensation (KCTP) has proven to be an excellent strategy toward the synthesis of well-defined conjugated polymers. In this report, Ni(0) species are reacted with surface-bound aryl bromides to yield KCTP initiators of structure (aryl)Ni(II)-Br. Surface-confined Kumada reactions are carried out with a ferrocene functionalized Grignard reagent to quantify initiator coverage, ligand exchange, and Kumada reaction kinetics. In addition, surface-initiated Kumada catalyst-transfer polycondensation (SI-KCTP) is carried out from the fabricated initiators to modify SiO(2) and ITO surfaces. Uniform poly(3-methylthiophene) films with thicknesses between 40 and 65 nm were characterized using a variety of spectroscopic and electrochemical techniques.

Formation of conjugated polymer brushes by surface-initiated catalyst-transfer polycondensation.

Electroactive conjugated polymer brushes of poly(thiophene) and poly(phenylene) have been prepared via a surface-initiated Kumada-type polycondensation reaction, yielding films with a thickness up to 42 nm.

Ranitidine therapy for gastroesophageal reflux disease. Results of a large double-blind trial.

In a multicenter, double-blind trial, 284 patients with gastroesophageal reflux disease were evaluated before, during, and after six weeks of treatment with either placebo or ranitidine (150 mg twice daily). Randomization resulted in two comparable patient groups. Ranitidine treatment was significantly more effective than placebo treatment in decreasing the frequency and the severity of heartburn during both daytime and nighttime assessment periods. There was a significant correlation between improvement in heartburn symptoms and decrease in antacid consumption; hence, patients receiving ranitidine consumed significantly fewer antacid tablets. Among patients with endoscopic esophagitis at baseline, the overall change in endoscopic classification after six weeks of therapy was significantly better for the ranitidine-treated patients. The ranitidine-treated group had less evidence of erosions and ulcerations as well as greater healing. There were no differences between the groups with respect to changes in esophageal mucosal sensitivity to acid perfusion or changes in histologic grading of esophageal mucosal biopsy specimens. The ranitidine safety profile was similar to that of previous studies. We conclude that, in patients with gastroesophageal reflux disease, ranitidine therapy, 150 mg twice daily, markedly reduced the heartburn symptoms of reflux disease and significantly improved the endoscopic appearance of the esophageal mucosa.

Why do the published data fail to clarify the relationship between gastroesophageal reflux and asthma?

The relationship between gastroesophageal reflux (GER) and asthma has troubled physicians for centuries and has been a source of debate among pulmonologists, allergists, and gastroenterologists for decades. Attempting to tie together the pieces of the puzzle, numerous investigators have struggled to show that in patients with asthma, GER symptoms occur too frequently, gastric acid dwells for too long in the esophageal lumen, and refluxed gastric acid injures the esophageal mucosa more than expected. Unfortunately, all of the work done by these fine investigators has failed to demonstrate a "cause and effect" relationship. Although they have succeeded in convincing us that GER occurs more frequently in asthmatics than in nonasthmatics, they still must continue until we all know how to predict which patients have gastroesophageal-induced or gastroesophageal-exacerbated asthma.

Gastroesophageal reflux and asthma.

The medical literature has been deluged with articles on the relation between gastroesophageal reflux (GER) and asthma. In an effort to piece together the complex puzzle, investigators from all disciplines have gathered their patients with wheezing and heartburn and studied the epidemiology, the possible cause or effect mechanisms and the therapeutic response to GER treatment. Indeed, since humans first began to hunker down and work together to discuss interesting observations, the world has begun to breathe easier. Epidemiological evidence for a GER/asthma association suggests that about three-fourths of asthmatics, independent of the use of bronchodilators, have acid GER, increased frequency of reflux episodes, or heartburn; and 40% have reflux esophagitis. Physiological studies suggest that 2 separate mechanisms are involved in the GER/asthma relationship: (1) a vagally mediated pathway and (2) microaspiration. In any given patient, however, there is no acceptable diagnostic method available to confirm the presence or absence of GER-induced asthma. Clinical trials, using antireflux medical therapy and antireflux surgery have begun to provide some clues about GER-related pulmonary symptoms. The trials of medical therapy using acid suppressing drugs (e.g. histamine-2 receptor antagonists) have ranged from no benefit to modest improvement of only nocturnal asthma symptoms. Studies with proton-pump inhibitors are underway. In uncontrolled surgical studies, antireflux surgery has resulted in partial or complete remission of asthma symptoms in a large proportion of patients. Despite the uncontrolled nature of these studies, many patients have had dramatic subjective improvement in pulmonary symptoms. It appears for now that clinical trials are the only available means to assess whether medical or surgical treatment of GER in patients with both GER and asthma improves the symptoms of asthma and decreases the need for pulmonary medications. One conclusion is certain: We no longer can ignore the important co-existent nature of these 2 afflictions.

Preventing death of Barrett's cancer: does frequent surveillance endoscopy do it?

Patients experiencing gastroesophageal reflux may be predisposed to developing Barrett's esophagus, which is thought to be a precursor for the development of esophageal cancer. Currently, endoscopic surveillance is recommended for patients with Barrett's esophagus in the hope that esophageal cancer may be detected or even prevented. However, the frequency of endoscopic evaluations is a matter of debate. This article will examine whether regular endoscopic surveillance can prevent death of Barrett's cancer. The issues that are evaluated include the death rate from esophageal cancer, the need to scope all patients with reflux, the need to perform surveillance on all patients with Barrett's esophagus, survival data for Barrett's patients, and the incidence of nonsymptomatic Barrett's cancer.

Prostaglandins in peptic ulcer disease. An overview of current status and future directions.

Naturally occurring prostaglandins almost certainly play an important role in maintaining the integrity of the gastrointestinal mucosa. Clinical evidence available to date indicates that synthetic analogues of prostaglandins heal gastroduodenal ulcer only in doses that suppress gastric acid. However, non-antisecretory doses of prostaglandins may eventually have a role in the treatment of ulcer disease by maintaining ulcer healing and preventing recurrence. This possibility along with the potential of prostaglandins to prevent gastroduodenal mucosal injury caused by NSAIDs, alcohol, aspirin and stress, if supported by the results of ongoing clinical trials, may prove to be a major therapeutic advance for the treatment of acid peptic disease.

Walking and chewing reduce postprandial acid reflux.

BACKGROUND: Gastro-oesophageal reflux is worse after meals, and antacids are usually consumed after dietary indiscretion. AIM: To investigate whether walking or gum chewing affect meal-induced gastro-oesophageal reflux. METHODS: The study population comprised 12 case subjects with gastro-oesophageal reflux disease and 24 healthy controls. Each subject was studied using pH-metry for 5 h on 3 separate days. After baseline recording of pH for 1 h, all subjects were fed a standard breakfast over a 20-min period. On one of the days, oesophageal pH was recorded after the 20-min eating period for an additional 4 h in the sitting position. On another day, postprandial oesophageal pH was recorded for the first hour whilst walking, and for 3 subsequent hours whilst sitting. During a third day, oesophageal pH was recorded for the first postprandial hour whilst gum-chewing, followed by 3 h of sitting. RESULTS: Food intake promoted gastro-oesophageal reflux in case subjects with GERD as well as in healthy controls, although postprandial reflux was more pronounced amongst the refluxers than amongst the controls. Chewing gum for 1 h after the meal reduced the acid contact time in both groups, with a more profound effect in refluxers than in controls. Whilst the beneficial effect of 1-h of gum-chewing lasted for up to 3 h in both groups, the beneficial effect of 1-h of walking was apparent only in refluxers, only to a mild degree, and only for a short duration. CONCLUSIONS: Chewing gum after a meal helps to reduce postprandial oesophageal acid exposure.

There are no reliable symptoms for erosive oesophagitis and Barrett's oesophagus: endoscopic diagnosis is still essential.

AIMS: To evaluate the sensitivity and specificity of different symptoms in erosive reflux oesophagitis and Barrett's oesophagus. METHODS: The presence of reflux symptoms was compared between a case population of 306 patients with endoscopically determined erosive reflux oesophagitis, 235 patients with biopsy-proven Barrett's oesophagus and a control population of 198 subjects without reflux disease. RESULTS: Heartburn at any time and heartburn at night represented the only two symptoms to be simultaneously sensitive and specific. Symptoms that were induced by various foods, such as fat, tomato, chocolate, citrus or spices, tended to cluster in the same sub-group of patients. Similarly, heartburn induced by exercise, lying down or bending over tended to occur in the same sub-groups. The frequency of symptoms was influenced more by the presence of mucosal erosions than by the presence of Barrett's oesophagus. Reflux symptoms occurred more frequently in the presence rather than the absence of Barrett's oesophagus, and in long segment rather than short segment of Barrett's mucosa. CONCLUSIONS: Endoscopic inspection of the oesophageal mucosa remains the only certain method by which to reliably diagnose erosive reflux oesophagitis and Barrett's oesophagus.

Reflux symptoms are associated with psychiatric disease.

AIMS: To evaluate the frequency of reflux symptoms in patients with a diagnosed psychiatric disorder and to assess potential risk factors for symptom occurrence. METHODS: The presence of reflux symptoms was compared between a case population of 94 psychiatric patients and a control population of 198 non-psychiatric patients. RESULTS: Heartburn, exercise-induced heartburn, cough and dysphagia were all reported significantly more frequently by subjects with psychiatric disorders than by control subjects. The presence of any psychiatric diagnosis exerted an increased risk for both heartburn (odds ratio, 2.71; 95% confidence interval, 1.01-7.30) and exercise-induced heartburn (3.34; 1.12-9.96). The type of psychiatric disorder, the type of psychotropic medication and the lifestyle did not influence the presence of reflux symptoms. CONCLUSIONS: Reflux symptoms occur more frequently in patients with than without a diagnosed psychiatric disorder. The reflux symptoms are not associated with any specific type of medication and may reflect a generally reduced threshold for or distorted perception of symptoms.

Inguinal hernia is not a sign of colon cancer: results of a prospective screening trial.

BACKGROUND: It has been suggested that patients with an inguinal hernia harbour an increased risk for colorectal cancer. METHODS: In a prospective clinical trial, we compared the prevalence of colonic neoplasms in 100 cases with inguinal hernia and 100 controls without inguinal hernia. The number, size, histology type, and the location of all colorectal lesions found during a screening flexible sigmoidoscopy were recorded. RESULTS: Not a single case of colorectal cancer was detected in the patients with inguinal hernia pending surgical repair. In the asymptomatic control subjects, one Dukes A and one Dukes B1 colon cancer were detected. Polypectomy was performed in 15% and 17% of the case and control subjects, respectively. During a 5-year period following the initial screening procedure, none of the case or control subjects was diagnosed with colon cancer. CONCLUSIONS: The decision for or against performing an endoscopic procedure in a patient with inguinal hernia should be guided by the general principles of screening for colorectal cancer. The mere presence of an inguinal hernia does not automatically increase the risk of colorectal cancer.

Lansoprazole heals erosive reflux oesophagitis in patients with Barrett's oesophagus.

BACKGROUND: Barrett's oesophagus is thought to be a complication of severe gastro-oesophageal reflux. AIM: To determine whether the proton pump inhibitor, lansoprazole, is effective in healing erosive reflux oesophagitis in patients with Barrett's oesophagus. METHODS: An 8-week, randomized, double-blind study was conducted using patients with both erosive reflux oesophagitis and Barrett's oesophagus. Erosive reflux oesophagitis was defined as grades 2-4 oesophagitis; Barrett's oesophagus, as specialized columnar epithelium obtained by biopsy from the tubular oesophagus; and healing, as a return to grade 0 or 1 oesophageal mucosa (complete re-epithelialization). One-hundred and five (105) patients from one centre were randomized to receive either lansoprazole 30 mg daily or ranitidine 150 mg twice daily. Unhealed or symptomatic lansoprazole patients at week 4 were randomized to receive the same 30 mg dose daily or an increased dose of 60 mg daily. Endoscopy was performed at baseline and at weeks 2, 4, 6 and 8. RESULTS: The treatment groups were similar in regards to baseline characteristics, erosive reflux oesophagitis grades and length of Barrett's oesophagus. At each 2-week interval, lansoprazole patients had significantly greater healing rates and less day and night heartburn and regurgitation than ranitidine patients. There were no significant differences between treatment groups in antacid use, quality of life parameters, or rate of reported adverse events. Median values for fasting serum gastrin levels remained within the normal range for both groups. CONCLUSION: In patients with both Barrett's oesophagus and erosive reflux oesophagitis, lansoprazole is significantly more effective than ranitidine in relieving reflux symptoms and healing erosive reflux oesophagitis.

Daily omeprazole surpasses intermittent dosing in preventing relapse of oesophagitis: a US multi-centre double-blind study.

INTRODUCTION: Relapse of erosive oesophagitis occurs in almost all patients if treatment is stopped after initial healing. AIM: To assess the potential of different therapeutic regimens of omeprazole to prevent relapse of erosive reflux oesophagitis after initial healing with omeprazole. PATIENTS AND METHODS: Patients whose active erosive reflux oesophagitis (grade > or = 2) had healed (grade 0 or 1) after 4-8 weeks of open-label omeprazole 40 mg daily (phase I) were eligible to join a multi-centre, 6-month double-blind, placebo-controlled maintenance study (phase II), which included endoscopy, symptom assessments, serum gastrin measurements, and gastric fundic biopsies. During phase I, endoscopy was performed at weeks 0, 4, and 8. At the end of phase I, 429 of 472 patients (91%) were healed, and there were significant reductions in heartburn, dysphagia and acid regurgitation. Of the 429 patients who healed, 406 joined phase II and were randomized to one of three groups: 20 mg omeprazole daily (n = 138), 20 mg omeprazole for 3 consecutive days each week (n = 137), or placebo (n = 131). During phase II, endoscopy was performed at months 1, 3, and 6 or at symptomatic relapse. RESULTS: The percentages of patients still in endoscopic remission at 6 months were 11% for placebo, 34% for omeprazole 3-days-a-week, and 70% for omeprazole daily. Both omeprazole regimens were superior to placebo in preventing recurrence of symptoms (P < 0.001); however, omeprazole 20 mg daily was superior to omeprazole 20 mg 3-days-a-week (P < 0.001). Compared to baseline, omeprazole therapy resulted in no significant differences among treatment groups in the distribution of gastric endocrine cells. CONCLUSIONS: These results show that after healing of erosive oesophagitis with 4-8 weeks of omeprazole, relapse of oesophagitis and recurrence of reflux symptoms can be prevented in 70% of patients with a maintenance regimen of 20 mg daily, but that intermittent dosing comprising 3 consecutive days each week significantly compromises efficacy.

The significance of intraepithelial eosinophils in the histologic diagnosis of gastroesophageal reflux.

Detection of intraepithelial eosinophils in esophageal mucosal biopsies has been suggested as histologic evidence of symptomatic gastroesophageal reflux (GER) disease in both children and adults. Previous studies have primarily examined symptomatic persons, and only one study included a comparison with normal controls. In the present study, the authors examined esophageal mucosal biopsies obtained by the hydraulic suction technic for the presence of intraepithelial eosinophils from 73 adult patients with subjective and objective evidence of GER disease and 12 asymptomatic adult volunteers in whom a series of esophageal function tests were normal. Intraepithelial eosinophils were identified in 23 (31.5%) of adult patients and in 4 (33.3%) of the asymptomatic volunteers. No clinical aspects in the GER patients correlated with the presence of eosinophils. By crude quantitation, rare eosinophils added little to more conventional assessment of histologic esophagitis and were present in one-third of normal subjects. The authors conclude that rare eosinophils in esophageal biopsies may not be a reliable criterion for the histologic assessment of GER disease.

Fecal occult blood testing: a false sense of security?

BACKGROUND: Recent screening studies with fecal occult blood testing (FOBT) report that one of three patients with colorectal cancer (CRC) can be cured of the disease; minimal attention has been given to the two of three patients who despite repeated screening go on to die of silent CRC. We report the known "miss rate" (known false negatives) of our 14-year ongoing program of FOBT that was organized in 1979 to detect early CRC. METHODS: From October 1979 through December 1993, 36,034 FOBT kits were distributed to patients who were without gastrointestinal complaints at Hines Veterans Affairs Hospital. The test was considered positive if at least one result of the six tests was positive and negative if the test result was equivocal. Patients with negative FOBT received a new test kit each year by mail. A positive test was followed by full colonoscopy or an air contrast barium enema if a full colonoscopy was not possible. RESULTS: The overall return rate was 47.8%. CRC was detected in 115 patients: 94 had a favorable and 21 had an unfavorable Duke's C or D or lymphoma prognosis. Of 21 patients 13 (62%) had initially tested FOBT negative (missed lesion). Of the 21 cases of advanced CRC 15 (71.43%) were in the descending, sigmoid, or rectosigmoid colon or rectum. CONCLUSIONS: (1) The majority (82%) of all CRC detected by FOBT screening are diagnosed at a favorable stage. (2) The majority of known advanced CRC (62%) escape early detection with FOBT. (3) Five (62.5%) of eight of the advanced CRC cases discovered on initial FOBT and 10 (76.9%) of 13 of advanced CRC cases missed on initial FOBT but detected in subsequent years were in the left colon and most likely in the range of the flexible sigmoidoscope. (4) FOBT as a sole screening test may provide a false sense of security, especially in patients with advanced left-side CRC.

Cholecystectomy in cirrhotic patients: a formidable operation.

Cholecystectomy and common bile duct exploration in cirrhotic patients is associated with an 83 percent mortality if prothrombin time is prolonged 2.5 seconds over control. The causes of death are related to complications of liver disease such as hepatic encephalopathy, ascites, sepsis and hemorrhage. If the prothrombin time is prolonged, major intraoperative blood loss can be anticipated, and blood and plasma transfusion requirements may be massive. Jaundice in the presence of cirrhosis requires careful preoperative evaluation and is most frequently due to hepatocellular disease rather than extrahepatic biliary obstruction. Cholecystectomy and common duct exploration in cirrhotic patients should be performed only for life-threatening complications of biliary tract disease such as empyema, perforation and ascending cholangitis.