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-initiated poly(3-methylthiophene) as a hole-transport layer for polymer solar cells with high performance.

In this work, uniform poly(3-methylthiophene) (P3MT) films are fabricated on indium-tin oxide (ITO) surfaces using surface-initiated Kumada catalyst-transfer polycondensation (SI-KCTP) from surface-bound arylnickel(II) bromide initiators. The P3MT interfacial layer is covalently bound to the ITO surface, thereby preventing possible delamination during the processing of additional layers. These surface-bound P3MT layers successfully serve as the hole-transport layer for solution-processed bulk heterojunction polymer solar cells. Efficiencies greater than 5% have been achieved on devices based on doped thin P3MT interfacial layers. Moreover, because of the excellent stability of the covalently immobilized P3MT on ITO substrates, devices based on reused P3MT/ITO substrates extracted from old devices exhibit efficiencies similar to those of the original devices.

On the Role of Disproportionation Energy in Kumada Catalyst-Transfer Polycondensation.

Kumada catalyst-transfer polycondensation (KCTP) is an effective method for the controlled polymerization of conjugated polymers. Nevertheless, side reactions leading to early termination and unwanted chain coupling cause deviations from the target molecular weight, along with increasing polydispersity and end group variation. The departure from the KCTP cycle stems from a disproportionation reaction that leads to experimentally observed side products. The disproportionation energies for a series of nickel-based initiators containing bidentate phosphino attendant ligands were computed using density functional theory at the B3LYP/DZP level. The initiator was found to be less favorable toward disproportionation by 0.5 kcal mol-1 when ligated by 1,3-bis(diphenylphosphino)propane (dppp) rather than 1,2-bis(diphenylphosphino)ethane (dppe). Trends in disproportionation energy (Edisp) with a variety of bidentate phosphine ligands match experimental observations of decreased polymerization control. Theoretical Edisp values can thus be used to predict the likelihood of disproportionation in cross-coupling reactions and, therefore, aid in catalyst design.

Transarterial chemoembolization for HCC in patients with extensive liver transplantation waiting times.

The treatment of hepatocellular cancer (HCC) with transarterial chemoembolization (TACE) prior to orthotopic liver transplant (OLT) is of increasing importance due to the rise in HCC incidence and donor shortage. This single-center study examines 28 patients treated with TACE and 7 patients not treated with TACE, with HCC prior to OLT between 1999 and 2008. The overall 1- and 5-year survival of all transplanted patients with HCC was 94% (33 of 35) and 80% (28 of 35). There was no difference in survival (P = .99) between patients who underwent transplantation immediately (median 95 days) and patients who had significantly longer wait times (median 308 days) when treated with TACE. During extensive wait times for OLT, TACE can be used to keep patients with HCC on the waiting list by preventing tumor progression, with similar outcomes compared with those who underwent transplantation immediately.

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.

Surface-initiated polymerization of conjugated polymers.

In this feature article, we highlight the recent developments in the chain growth polymerization mechanism of conjugated polymers. With a particular emphasis on Kumada catalyst-transfer polycondensation, this article focuses on the surface-initiated polymerization of conjugated polymers, along with the opportunities and challenges associated with this technique.

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.

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.

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.

Gastric surgery is not a risk for Barrett's esophagus or esophageal adenocarcinoma.

BACKGROUND & AIMS: The contribution of duodeno-gastroesophageal reflux to the development of Barrett's esophagus has remained an interesting but controversial topic. The present study assessed the risk for Barrett's esophagus after partial gastrectomy. METHODS: The data of outpatients from a medicine and gastroenterology clinic who underwent upper gastrointestinal endoscopy for any reason were analyzed in a case-control study. A case population of 650 patients with short- segment and 366 patients with long-segment Barrett's esophagus was compared in a multivariate logistic regression to a control population of 3047 subjects without Barrett's esophagus or other types of gastroesophageal reflux disease. RESULTS: In the case population, 25 (4%) patients with short-segment and 15 (4%) patients with long-segment Barrett's esophagus presented with a history of gastric surgery compared with 162 (5%) patients in the control population, yielding an adjusted odds ratio of 0.89 with a 95% confidence interval of 0.54-1.46 for short-segment and an adjusted odds ratio of 0.71 (0.30-1.72) for long-segment Barrett's esophagus. Similar results were obtained in separate analyses of 64 patients with Billroth-1 gastrectomy, 105 patients with Billroth-2 gastrectomy, and 33 patients with vagotomy and pyloroplasty for both short- and long-segment Barrett's esophagus. Caucasian ethnicity, the presence of hiatus hernia, and alcohol consumption were all associated with elevated risks for Barrett's esophagus. CONCLUSIONS: Gastric surgery for benign peptic ulcer disease is not a risk factor for either short- or long-segment Barrett's esophagus. This lack of association between gastric surgery and Barrett's esophagus suggests that reflux of bile without acid is not sufficient to damage the esophageal mucosa.

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.

No association between gallstones and gastroesophageal reflux disease.

OBJECTIVES: Gallstones and hiatal hernia reportedly have been linked to similar dietary factors prevalent in western countries, and patients with cholelithiasis or previous cholecystectomy have been reported to have more duodenogastric reflux than healthy controls. Nonetheless, the contribution of duodenogastric reflux to the development of gastroesophageal reflux disease (GERD) remains controversial. The present study was aimed to assess the association between gallstone disease and GERD. METHODS: Outpatients from general medical clinics who underwent upper GI endoscopy and abdominal ultrasonography were recruited into a case-control study. A case population of 790 patients with various grades of GERD was compared to a control population of 407 patients without GERD. In a multivariate logistic regression, the presence of GERD served as the outcome variable, whereas the presence of gallstones, hiatal hernia, social habits, and demographic characteristics served as predictor variables. RESULTS: No associations were found between the presence of cholelithiasis or previous cholecystectomy and GERD or between the presence of cholelithiasis or previous cholecystectomy and hiatal hernia. The severity of GERD also remained unaffected by the presence of gallstones. The occurrence of GERD was influenced only by hiatal hernia (odds ratio [OR] = 3.15, 95% CI = 2.44-4.08), alcohol consumption (OR = 1.47, CI = 1.08-1.99), and not by cholelithiasis (OR = 1.02, CI = 0.68-1.51), or cholecystectomy (OR = 0.90, CI = 0.64-1.28). The frequency of GERD among hiatus hernia patients with gallstones (437/592 = 74%) was similar to the frequency of GERD among hiatus hernia patients without gallstones (168/220 = 76%, p = 0.516). CONCLUSIONS: Neither cholelithiasis nor cholecystectomy poses a risk for the occurrence of GERD or hiatal hernia. Gallstone disease does not seem to influence the integrity of the esophageal mucosa through GERD.

Comparing lansoprazole and omeprazole in onset of heartburn relief: results of a randomized, controlled trial in erosive esophagitis patients.

OBJECTIVE: This randomized, double-blind, multicenter study was conducted to confirm a previous finding that lansoprazole relieves heartburn faster than omeprazole in patients with erosive esophagitis. METHODS: A total of 3510 patients with erosive esophagitis and at least one episode of moderate to very severe daytime and/or nighttime heartburn during the 3 days immediately before the screening visit were randomized to lansoprazole 30 mg once daily or omeprazole 20 mg once daily for 8 wk. Patients recorded the presence and severity of daytime and nighttime heartburn in daily diaries. On treatment days 1-4, patients were telephoned to confirm the completion of their daily diary. The primary efficacy parameters were the percentage of heartburn-free days and heartburn-free nights, as well as the average severity of daytime and nighttime heartburn. RESULTS: During treatment day I and all evaluation time points including the entire 8-wk treatment period, significantly (p < 0.05) higher percentages of patients treated with lansoprazole than those treated with omeprazole did not experience a single episode of heartburn. Onset of heartburn relief was more rapid in lansoprazole-treated versus omeprazole-treated patients: on day 1, 33% versus 25% of lansoprazole- versus omeprazole-treated patients were heartburn-free. The percentages of heartburn-free days and heartburn-free nights were also significantly (p < 0.01) greater for patients treated with lansoprazole at all evaluation time points. Heartburn severity was significantly less among those treated with lansoprazole compared with omeprazole. Both treatments were safe and well tolerated. CONCLUSIONS: Over 8 wk, lansoprazole 30 mg once daily relieved heartburn symptoms faster and more effectively than omeprazole 20 mg once daily in patients with erosive esophagitis.

Temporal associations between coughing or wheezing and acid reflux in asthmatics.

BACKGROUND AND AIMS: The pulmonary symptoms of patients with lung disease may be ascribed to gastro-oesophageal reflux although a causal relationship between acid reflux and coughing or wheezing has not been proved. Does cough cause reflux or does reflux cause cough? The aim of this study was to evaluate 24 hour oesophageal pH tracings of asthmatics with gastro-oesophageal reflux to determine the temporal association between acid reflux and coughing or wheezing. METHODS: The oesophageal tracings of 128 asthmatics from the outpatient clinics who underwent oesophagogastroduodenoscopy, oesophageal manometry, and 24 hour oesophageal pH monitoring were analysed. Three possible temporal relationships between the occurrence of acid reflux and the occurrence of coughs or wheezes were evaluated: (1) pulmonary symptoms preceding reflux; (2) reflux preceding pulmonary symptoms; and (3) unrelated occurrence of both events. RESULTS: Of 128 asthmatics, 53 recorded five or more coughs and 19 recorded three or more wheezes during the 24 hour recording period. Mean acid contact time was similar in asthmatics with and without pulmonary symptoms (12.2 (1.2)% v 10.4 (0.6)%). Of all coughs and wheezes, 46% and 48%, respectively, were associated with acid reflux. For the individual asthmatic, the likelihood of reflux induced coughing increased as the number of coughs increased. CONCLUSIONS: Half of all coughs and wheezes in asthmatics are associated with acid reflux into the oesophagus. While an occasional coughing episode can lead to reflux, it is rather the reflux episode in the vast majority of instances that leads to cough.

Risk factors of oesophagitis in arthritic patients.

BACKGROUND: The risk factors that precipitate the occurrence of oesophageal mucosal injury in patients on continuous nonsteroidal anti-inflammatory drug (NSAID) therapy are unknown. METHODS: Outpatients who regularly consumed NSAIDs for osteoarthritis were recruited from a rheumatology clinic into a prospective case-control study. All patients answered a structured interview and underwent upper gastrointestinal endoscopy. RESULTS: Of 450 eligible patients, 195 (43%) consented to be interviewed and undergo upper gastrointestinal endoscopy. Oesophagitis was diagnosed in 41 of these 195 patients (21%). The occurrence of gastric or duodenal ulcer in individual patients did not predict the concomitant damage of the oesophageal mucosa. Young age (odds ratio: 1.79 per decade of life; 95% confidence interval: 1.11-2.86) and hiatus hernia (odds ratio: 3.72; 95% confidence interval: 1.63-8.49) both increased the risk of developing oesophagitis. When questioned, all oesophagitis patients revealed at least one gastrointestinal symptom, heartburn being named most frequently (odds ratio: 4.78; 95% confidence interval: 2.04-11.17). The type of anti-inflammatory medication, the use of alcohol and the use of nicotine were not associated with any significant risk for erosive oesophagitis. CONCLUSIONS: Patients on chronic NSAID therapy for rheumatological disease suffer frequently from erosive oesophagitis. While the risk may be higher in patients with a pre-existing tendency for gastro-oesophageal reflux, any concomitant history of NSAID-induced peptic ulcer disease does not add to the risk. Erosive oesophagitis should be considered especially in patients on NSAIDs who complain of heartburn.

Is there a link between cervical inlet patch and Barrett's esophagus?

BACKGROUND: Heterotopic gastric-type mucosa occurs as a flat island or islands of red mucosa in the proximal third of the esophagus where it gives rise to the "cervical inlet patch" (CIP). The aim of the present study was to delineate the clinical epidemiology of the CIP, especially its possible relationship to Barrett's esophagus. METHODS: A case-control study compared 53 case subjects with CIP and 4882 control subjects without CIP. In a multivariate logistic regression, the presence of CIP was chosen as the outcome variable, whereas demographic characteristics, social habits, and presence of other endoscopic diagnoses served as predictor variables. RESULTS: The prevalence of CIP was 1.1%. Its presence was associated with hiatal hernia (odds ratio 2.26: 95% CI [1.12, 4.56]) gastric ulcer (2.93: 95% CI [1.34, 6.40]) and Barrett's esophagus (4.41: 95% CI [2.31, 8.41]). CONCLUSIONS: The coincidence of the cervical inlet patch and Barrett's esophagus could suggest a shared embryonic etiology.