pH-Responsive quantum dots (RQDs) that combine a fluorescent nanoparticle with a pH-sensitive dye.

A quantum dot conjugated to a dye through an experimentally simple process of self-assembly exhibits an enhanced emission when the dye is attached, and this effect is pH-sensitive.

Pancreatic duct obstruction in rabbits causes digestive zymogen and lysosomal enzyme colocalization.

The pancreatic duct of anesthetized rabbits was cannulated and, in some animals, flow of pancreatic exocrine secretions was blocked by raising the cannula to a vertical position. Blockage for 3-7 h caused a rapid and significant rise in serum amylase activity and an increase in amylase activity within the pancreas. The concentration of lysosomal enzymes in the pancreas was not altered but they became redistributed among subcellular fractions and, as a result, an increased amount was recovered in the 1,000-g, 15-min pellet, which was enriched in zymogen granules. Immunofluorescence studies indicated that lysosomal enzymes become localized within organelles which, in size and distribution, resemble zymogen granules. They also contain digestive enzyme zymogens. Blockage of pancreatic secretions also caused lysosomal enzyme-containing organelles to become more fragile and subject to in vitro rupture. These changes noted after short-term pancreatic duct obstruction are remarkably similar to those previously noted to occur during the early stages of diet and secretagogue-induced experimental pancreatitis, observations that have suggested that colocalization of digestive enzyme zymogens and lysosomal hydrolases might result in intracellular digestive enzyme activation and be an important early event in the evolution of those forms of experimental acute pancreatitis.

Epithelial-mesenchymal transition (EMT) and activated extracellular signal-regulated kinase (p-Erk) in surgically resected pancreatic cancer.

BACKGROUND: EMT or transformation to the mesenchymal phenotype plays an important role in tumor invasion and metastasis. In vitro data suggest that mesenchymal transformation may correlate with the activation of PI3 kinase and Ras/Erk pathways. We investigated the expression of EMT markers (low E-cadherin, high fibronectin, and vimentin) and their association with p-Erk in resected pancreatic cancer. METHODS: Clinical data/surgical specimens from 34 consecutive pancreatic cancer patients (pts) who underwent pancreatectomy were included. Immunohistochemical staining was performed on formalin-fixed paraffin-embedded tissues using monoclonal antibodies against vimentin, fibronectin, E-cadherin, and p-Erk. The results were correlated with clinicopathological parameters and survival. Survival analysis (log-rank test, Cox proportional hazard model), categorical data analysis (Pearson's chi-square, Fisher's exact test) and Kendall's tau were performed at a significance level of 0.05. RESULTS: The patient population was formed from 13 males and 21 females, with a median age of 66 years (range 38-84 years); American Joint Committee on Cancer (AJCC) stage 1 (n = 2), 2 (n = 27), 3 (n = 5); histological grade 1 (n = 4), 2 (n = 13), 3 (n = 16), 4 (n = 1). Median survival was 15 months (95% CI: 11-24 months). Fibronectin overexpression correlated with the presence of vimentin (p = 0.0048) and activated Erk (p = 0.0264). There was a borderline association of fibronectin with worsening grade (p = 0.06). A negative association between vimentin and E-cadherin was noted (p = 0.0024). Increased fibronectin or vimentin and decreased E-cadherin correlated with poor survival. CONCLUSION: EMT is associated with poor survival in surgically resected pancreatic adenocarcinoma. A correlation between activated Erk and fibronectin was identified that may open avenues for targeted therapy for this subgroup.

Alternative oxidation by isopenicillin N synthase observed by X-ray diffraction.

BACKGROUND: Isopenicillin N synthase (IPNS) catalyses formation of bicyclic isopenicillin N, precursor to all penicillin and cephalosporin antibiotics, from the linear tripeptide delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine. IPNS is a non-haem iron(II)-dependent enzyme which utilises the full oxidising potential of molecular oxygen in catalysing the bicyclisation reaction. The reaction mechanism is believed to involve initial formation of the beta-lactam ring (via a thioaldehyde intermediate) to give an iron(IV)-oxo species, which then mediates closure of the 5-membered thiazolidine ring. RESULTS: Here we report experiments employing time-resolved crystallography to observe turnover of an isosteric substrate analogue designed to intercept the catalytic pathway at an early stage. Reaction in the crystalline enzyme-substrate complex was initiated by the application of high-pressure oxygen, and subsequent flash freezing allowed an oxygenated product to be trapped, bound at the iron centre. A mechanism for formation of the observed thiocarboxylate product is proposed. CONCLUSIONS: In the absence of its natural reaction partner (the N-H proton of the L-cysteinyl-D-valine amide bond), the proposed hydroperoxide intermediate appears to attack the putative thioaldehyde species directly. These results shed light on the events preceding beta-lactam closure in the IPNS reaction cycle, and enhance our understanding of the mechanism for reaction of the enzyme with its natural substrate.

Persistent acute pancreatitis. A variant treated by pancreatoduodenectomy.

Acute pancreatitis usually subsides spontaneously or is complicated by pseudocysts, pancreatic necrosis, or abscesses. We describe an uncommon variant of acute pancreatitis in which signs of inflammation persist over a number of months, waxing and waning but never disappearing. Neither identifiable collections nor other targets for surgical drainage develop in these patients, nor does their condition ever remit enough to allow them to leave the hospital. Eating provokes a flareup of inflammation. We have treated five such patients with a pancreatoduodenectomy (four patients) or total pancreatectomy (one patient). Each patient had been continuously hospitalized for six to 12 weeks before operation. All survived the operation and left the hospital eating solid food within 16 days. In addition to acute inflammation and fat necrosis, the resected specimens showed main pancreatic duct stenosis or occlusion in three patients, a pancreaticoduodenal fistula in one, and a congenital duplication cyst. Pancreatography or cholangiography showed the lesion in three of four cases and helped in planning therapy. Thus, acute pancreatitis may fall to remit because of proximal pancreatic duct obstruction, for which pancreatoduodenectomy is a reasonable and effective treatment.

Polarization vision in cuttlefish in a concealed communication channel?

Polarization sensitivity is well documented in marine animals, but its function is not yet well understood. Of the cephalopods, squid and octopus are known to be sensitive to the orientation of polarization of incoming light. This sensitivity arises from the orthogonal orientation of neighboring photoreceptors. Electron microscopical examination of the retina of the cuttlefish Sepia officinalis L. revealed the same orthogonal structure, suggesting that cuttlefish are also sensitive to linearly polarized light. Viewing cuttlefish through an imaging polarized light analyzer revealed a prominent polarization pattern on the arms, around the eyes and on the forehead of the animals. The polarization pattern disappeared when individuals lay camouflaged on the bottom and also during extreme aggression display, attacks on prey, copulation and egg-laying behavior in females. In behavioral experiments, the responses of cuttlefish to their images reflected from a mirror changed when the polarization patterns of the reflected images were distorted. These results suggest that cuttlefish use polarization vision and display for intraspecific recognition and communication.

A simple and efficient method of measuring in vitro amylase secretion by dispersed pancreatic acini.

A method of measuring amylase secretion from dispersed pancreatic acini is described that utilizes a 20-micron nylon mesh to separate cell-associated from secreted amylase. When compared with the standard centrifugation assay, the mesh technique permits easy measurement at multiple, closely spaced time points while reducing the number of samples generated and allowing rapid manipulation of the extracellular suspending medium.

Effects of pulsatile glucose stimuli on long-term insulin secretory patterns in islets of Langerhans microdissected from Syrian hamsters.

The long-term effects of continuous and pulsatile glucose stimulation of islets of Langerhans microdissected from Syrian hamsters were examined. In the presence of a continuous glucose stimulus insulin secretion peaked during the first 3 h of stimulation followed by a decrease. In the presence of 11.2 mM glucose a second smaller peak of insulin secretion was observed 14-16 h after the perifusion started. Irrespective of the glucose concentration, insulin secretion then steadily decreased and reached very low levels by the end of the 48-h perifusion. However, glucose stimulus provided in a pulsatile manner appeared to reduce this rate of decrease in insulin secretion. Thus, after 48 h, islets exposed to the pulsatile glucose stimulus showed greater insulin responsiveness to glucose than those exposed to a constant glucose stimulus.

Diagnosis of symptomatic alkaline reflux gastritis and prediction of response to bile diversion operation by intragastric alkali provocation.

Because accurate diagnosis of the alkaline reflux gastritis syndrome has been elusive, surgical treatment has had a high failure rate, particularly with respect to relief of pain. We have used intragastric infusion of alkali as a provocative test in 147 patients with symptoms and endoscopic findings suggestive of bile gastritis and in 19 asymptomatic control subjects. Subjects received saline solution, 0.1 normal hydrochloric acid, and 0.1 normal sodium hydroxide solutions, as well as their own gastric aspirates in random blinded fashion by a nasogastric tube. There were no complications. A positive test result was defined as pain with sodium hydroxide but not with saline solution or hydrochloric acid infusion. All of the control subjects had negative test results. A total of 87 percent of the symptomatic patients have been followed (mean 4.3 years, minimum 1 year); 47 of those 128 had a Roux-Y gastrojejunal reconstruction to divert duodenal contents from the stomach. Correlation of the test results and the subsequent clinical status showed 87 percent of those with negative test results improved spontaneously or with other treatment versus 15 percent if the test results were positive (p less than 0.001), and 78 percent of those with positive test results had lasting relief of pain after surgical diversion versus a 30 percent success rate if the test results were negative (p less than 0.01). We conclude that positive alkali infusion test results predict that symptoms will likely respond best to surgical diversion of duodenal contents, and that negative test results should be a strong deterrent to surgical diversion. The test is safe, simple, and deserves further trial.

Obsessionality and the attempted suppression of unpleasant personal intrusive thoughts.

To explore the role of the thought enhancement and thought rebound effects in obsessionality, the relationship between obsessional symptomology and responding during and after the attempted suppression of unpleasant personal intrusive thoughts was examined. Ss first completed the Maudsley Obsessive Compulsive Inventory (MOCI) [Rachman and Hodgson, 1980]. Later, Ss indicated their most frequent intrusive thought and then completed a thought suppression protocol in which they first expressed, then suppressed, and, again, expressed that thought. Ss' scores on the MOCI were examined in relation to their pattern of responding in the suppression protocol to investigate whether Ss who were higher in obsessionality were more prone to enhancement and/or rebound effects with an unpleasant personal intrusive thought than Ss who were lower in obsessionality. The following results were obtained: (1) there was a positive relationship between obsessionality levels and thought enhancement for female Ss; (2) there was a negative relationship between obsessionality levels and thought enhancement for male Ss; and (3) there was no relationship between obsessionality levels and thought rebound. These findings suggest that the rebound effect is unrelated to obsessionality and that the enhancement effect relationship to obsessionality may be more complex than previously hypothesized.

Predictors of thought rebound.

Individual differences in the paradoxical thought rebound effect (increased thought expression following attempted thought suppression) were examined in two studies. In these two studies, the majority of Ss did not evidence thought rebound and, in both studies, it was found that a measure of thought rebound was correlated with other variables. In Study 1, a four-factor regression model predicted thought rebound (R2 = 0.1477). The significant predictors were: (1) ACT Composite (higher ACT predicted more rebound); (2) gender, (3) thought intrusion frequency during suppression; and (4) the interaction of gender and thought intrusion frequency (for male Ss only, more thought intrusions during suppression predicted more rebound). In Study 2, a replication regression model (R2 = 0.1408) cross-validated the ACT effect observed in Study 1. A Study 2 extension model (R2 = 0.2154) found the following significant predictors of thought rebound: (1) obsessionality (less obsessionality predicted more rebound); (2) trait anxiety (less anxiety predicted more rebound); (3) race (whites rebounded more than blacks); (4) gender; (5) 16 PF independence; and (6) the interaction of gender and 16 PF independence (for male Ss only, more independence predicted more rebound). The implications of these results for thought rebound theory are discussed.

Medicolegal issues.

Malpractice claims for failure to diagnose breast cancer are on the increase. Obstetrician-gynecologists are frequently targeted as defendants in these claims. A significant increase in the frequency and severity of these claims can be predicted by virtue of the widespread incidence and severity of the disease, coupled with changes in tort law. Physicians can learn risk management and loss prevention techniques by studying claims data and actual medical malpractice cases.

Heavy drinking from the freshman year into early young adulthood: the roles of stress, tension-reduction drinking motives, gender and personality.

OBJECTIVE: This study investigated the relationship between stress (defined alternatively as negative life events and emotional distress) and heavy drinking across late adolescence and early young adulthood, as well as the roles of tension-reduction drinking motives and gender as moderators of that relationship. The role of personality variables (neuroticism, behavioral undercontrol and extraversion) as moderators also was explored. METHOD: The data were obtained from 485 individuals (255 women) participating in a five-wave longitudinal study that spanned 7 years. The effects on heavy drinking of stress (either negative life events or emotional distress), tension-reduction drinking motives, gender and personality were analyzed each year with hierarchical multiple regression. RESULTS: Stress (negative life events) was positively related to heavy drinking, but only for men with stronger tension-reduction drinking motives at Year 4 (age 21). The relationship between tension-reduction drinking motives and heavy drinking was positive, developmentally graded, and moderated by gender, after the freshman year, the role of tension-reduction drinking motives in heavy drinking became less important for women, relative to men, a trend that grew stronger after the college years. Behavioral undercontrol played a limited role in the relationship of gender and tension-reduction drinking motives to heavy drinking. CONCLUSIONS: The findings have implications for theories of stress-related and stress-motivated drinking. Such theories should consider developmental processes, particularly the transition to adult drinking status at age 21 and the roles of tension-reduction drinking motives, gender and behavioral undercontrol.

Alcohol use disorders and neuropsychological functioning in first-year undergraduates.

The relation between alcohol use disorders and neuropsychological functioning was examined in 489 first-year undergraduates, approximately half of whom had a history of alcoholism in their biological fathers. Factor analyses of 17 neuropsychological tests and subtests produced the following 5 factors that were the basis of subsequent analyses: Language/Verbal Memory, Visuospatial Ability, Motor Speed, Booklet Category Performance, and Attention. Participants with alcohol use disorders showed deficits in visuospatial ability. Those who had alcohol dependence showed deficits in both visuospatial ability and motor speed relative to participants who abused alcohol. The differences in neuropsychological functioning remained even after several potential confounding variables were controlled statistically. Results suggest that alcohol use disorders in first-year college students are associated with deficits in neuropsychological measures that are not attributable to several potential third-variable explanations.

Assessment of impact of information booklets on use of healthcare services: randomised controlled trial.

OBJECTIVES: To investigate the effect of patient information booklets on overall use of health services, on particular types of use, and on possible interactions between use, deprivation category of the area in which respondents live, and age. To investigate the possibility of a differential effect on health service use between two information booklets. DESIGN: Randomised controlled trial of two patient information booklets (covering the management and treatment of minor illness). SETTING: 20 general practices in Lothian, Scotland. PARTICIPANTS: Random sample of patients from the community health index (n=4878) and of those contacting out of hours services (n=4530) in the previous 12 months in each of the study general practices. INTERVENTION: Booklets were posted to participants in intervention groups (3288 were sent What Should I Do?; 3127 were sent Health Care Manual). Patients randomised to control group (2993) did not receive a booklet. MAIN OUTCOME MEASURES: Use of health services audited from patients' general practice notes in 12 months after receipt of booklet. RESULTS: Receipt of either booklet had no significant effect on health service use compared with a control group. However, nine out of ten matched practices allocated to receive Health Care Manual had reduced consultation rates compared with matched practices allocated to What Should I Do? CONCLUSION: Widespread distribution of information booklets about the management of minor illness is unlikely to reduce demand for health services.

Individual differences in the Wegner rebound effect: evidence for a moderator variable in thought rebound following thought suppression.

Wegner, Schneider, Carter, and White in 1987 found that attempts to suppress thoughts of a white bear produced even greater preoccupation with that stimulus--a rebound effect. This effect was investigated in Exp. 1 using both Wegner's white bear stimulus and a more personally meaningful stimulus (an upcoming test). The rebound effect was not observed with either stimulus. Exp. 2 was conducted to examine the hypothesis that this failure to replicate Wegner, et al.'s rebound effect reflected individual differences in the respective subject pools. A within-subjects design was used to classify subjects as rebounders or nonrebounders by comparing each subject's expression of a thought following suppression to their own baseline expression of that thought. Subjects classified as rebounders had significantly higher ACT Mathematics subtest scores than did the subjects classified as nonrebounders. This suggests that there is a moderator variable related to mathematics ability for the rebound effect.

Diketoacid inhibitors of HIV-1 integrase: from L-708,906 to raltegravir and beyond.

HIV-1 integrase is one of the three viral enzymes essential to HIV replication. Consequently the development of therapeutics targeting this enzyme has been a major focus of antiretroviral research over the past two decades. Several classes of integrase inhibitors have been identified; of these the diketoacids (DKAs) show greatest promise: raltegravir (Merck & Co) has been approved by the US Food and Drug Administration (FDA) for HIV-1 therapy, while elvitegravir (Gilead Sciences/ Japan Tobacco) has reached phase III clinical trials. This review considers the development of DKA-based inhibitors from early screening studies through to the release of raltegravir. SAR data collated from numerous studies are compared and analysed, shedding light on the geometric and electronic requirements for effective binding to HIV-1 integrase. This information will in turn aid the rational design of future generations of integrase inhibitors.