Pandemic play moderates the relation between caregiver stress and child emotional distress in contexts of economic adversity

It is well-established that caregiver stress is linked to increased emotional distress among children, and recent evidence highlights similar associations between caregiver and child emotional well-being during the coronavirus (COVID-19) pandemic. Examining protective factors and coping mechanisms that are associated with resiliency in the face of pandemic-related stress can highlight potential strategies that may help children adapt to other unexpected hardships outside of a global pandemic. Previous research found that playing about the pandemic moderated an association between caregiver stress and children's emotional distress. However, few studies have explored "pandemic play" among children from low-income households, where pandemic-related stressors were often exacerbated. In the present study, 72 caregivers of Head Start preschoolers between 3 and 6  years of age were surveyed between late 2020 and early 2021. Results revealed that 32% of children engaged in pandemic play frequently. Caregiver stress was positively associated with child emotional distress, but only among children who did not engage in pandemic play frequently. These findings support the idea that child-directed play may be a developmentally appropriate and accessible coping mechanism to reduce the emotional burden of stressful events on children, regardless of economic context.

Textbook outcome following oesophagectomy for cancer: international cohort study

Background

Textbook outcome has been proposed as a tool for the assessment of oncological surgical care. However, an international assessment in patients undergoing oesophagectomy for oesophageal cancer has not been reported. This study aimed to assess textbook outcome in an international setting.

Methods

Patients undergoing curative resection for oesophageal cancer were identified from the international Oesophagogastric Anastomosis Audit (OGAA) from April 2018 to December 2018. Textbook outcome was defined as the percentage of patients who underwent a complete tumour resection with at least 15 lymph nodes in the resected specimen and an uneventful postoperative course, without hospital readmission. A multivariable binary logistic regression model was used to identify factors independently associated with textbook outcome, and results are presented as odds ratio (OR) and 95 per cent confidence intervals (95 per cent c.i.).

Results

Of 2159 patients with oesophageal cancer, 39.7 per cent achieved a textbook outcome. The outcome parameter ‘no major postoperative complication’ had the greatest negative impact on a textbook outcome for patients with oesophageal cancer, compared to other textbook outcome parameters. Multivariable analysis identified male gender and increasing Charlson comorbidity index with a significantly lower likelihood of textbook outcome. Presence of 24-hour on-call rota for oesophageal surgeons (OR 2.05, 95 per cent c.i. 1.30 to 3.22; P = 0.002) and radiology (OR 1.54, 95 per cent c.i. 1.05 to 2.24; P = 0.027), total minimally invasive oesophagectomies (OR 1.63, 95 per cent c.i. 1.27 to 2.08; P < 0.001), and chest anastomosis above azygous (OR 2.17, 95 per cent c.i. 1.58 to 2.98; P < 0.001) were independently associated with a significantly increased likelihood of textbook outcome.

Conclusion

Textbook outcome is achieved in less than 40 per cent of patients having oesophagectomy for cancer. Improvements in centralization, hospital resources, access to minimal access surgery, and adoption of newer techniques for improving lymph node yield could improve textbook outcome.

Textbook outcome following oesophagectomy for cancer: international cohort study

BACKGROUND

Textbook outcome has been proposed as a tool for the assessment of oncological surgical care. However, an international assessment in patients undergoing oesophagectomy for oesophageal cancer has not been reported. This study aimed to assess textbook outcome in an international setting.

METHODS

Patients undergoing curative resection for oesophageal cancer were identified from the international Oesophagogastric Anastomosis Audit (OGAA) from April 2018 to December 2018. Textbook outcome was defined as the percentage of patients who underwent a complete tumour resection with at least 15 lymph nodes in the resected specimen and an uneventful postoperative course, without hospital readmission. A multivariable binary logistic regression model was used to identify factors independently associated with textbook outcome, and results are presented as odds ratio (OR) and 95 per cent confidence intervals (95 per cent c.i.).

RESULTS

Of 2159 patients with oesophageal cancer, 39.7 per cent achieved a textbook outcome. The outcome parameter 'no major postoperative complication' had the greatest negative impact on a textbook outcome for patients with oesophageal cancer, compared to other textbook outcome parameters. Multivariable analysis identified male gender and increasing Charlson comorbidity index with a significantly lower likelihood of textbook outcome. Presence of 24-hour on-call rota for oesophageal surgeons (OR 2.05, 95 per cent c.i. 1.30 to 3.22; P = 0.002) and radiology (OR 1.54, 95 per cent c.i. 1.05 to 2.24; P = 0.027), total minimally invasive oesophagectomies (OR 1.63, 95 per cent c.i. 1.27 to 2.08; P < 0.001), and chest anastomosis above azygous (OR 2.17, 95 per cent c.i. 1.58 to 2.98; P < 0.001) were independently associated with a significantly increased likelihood of textbook outcome.

CONCLUSION

Textbook outcome is achieved in less than 40 per cent of patients having oesophagectomy for cancer. Improvements in centralization, hospital resources, access to minimal access surgery, and adoption of newer techniques for improving lymph node yield could improve textbook outcome.

Postoperative outcomes in oesophagectomy with trainee involvement

BACKGROUND

The complexity of oesophageal surgery and the significant risk of morbidity necessitates that oesophagectomy is predominantly performed by a consultant surgeon, or a senior trainee under their supervision. The aim of this study was to determine the impact of trainee involvement in oesophagectomy on postoperative outcomes in an international multicentre setting.

METHODS

Data from the multicentre Oesophago-Gastric Anastomosis Study Group (OGAA) cohort study were analysed, which comprised prospectively collected data from patients undergoing oesophagectomy for oesophageal cancer between April 2018 and December 2018. Procedures were grouped by the level of trainee involvement, and univariable and multivariable analyses were performed to compare patient outcomes across groups.

RESULTS

Of 2232 oesophagectomies from 137 centres in 41 countries, trainees were involved in 29.1 per cent of them (n = 650), performing only the abdominal phase in 230, only the chest and/or neck phases in 130, and all phases in 315 procedures. For procedures with a chest anastomosis, those with trainee involvement had similar 90-day mortality, complication and reoperation rates to consultant-performed oesophagectomies (P = 0.451, P = 0.318, and P = 0.382, respectively), while anastomotic leak rates were significantly lower in the trainee groups (P = 0.030). Procedures with a neck anastomosis had equivalent complication, anastomotic leak, and reoperation rates (P = 0.150, P = 0.430, and P = 0.632, respectively) in trainee-involved versus consultant-performed oesophagectomies, with significantly lower 90-day mortality in the trainee groups (P = 0.005).

CONCLUSION

Trainee involvement was not found to be associated with significantly inferior postoperative outcomes for selected patients undergoing oesophagectomy. The results support continued supervised trainee involvement in oesophageal cancer surgery.

Child Adjustment During COVID-19: The Role of Economic Hardship, Caregiver Stress, and Pandemic Play

The coronavirus disease 2019 (COVID-19) led to many lifestyle changes and economic hardships for families with young children. Previous research on risk and resilience highlights that children's adjustment to family hardships is influenced by caregiver stress, but individual child behaviors and characteristics may protect children from negative outcomes. Interestingly, many children have been reported to incorporate COVID-19 themes in their pretend play. Theory suggests children may do so to cope with pandemic-related stress, but no empirical studies have explored this possibility. The purpose of this study was to understand the process by which COVID-19 economic hardships experienced by a family were related to children's emotional well-being and development and to investigate how this process may vary as a function of children's engagement in pandemic-related pretend play. Caregivers (N = 99; mostly high earning families) of preschoolers ages 3-6 years (51% girls, 82% White) living in the United States participated in an online survey at two time points during the pandemic. Result revealed that COVID-19 economic hardships were related to increased caregiver stress, which, in turn, was associated with children's emotional distress and poorer self-regulation. However, engaging in pandemic-related pretend play appeared to protect children's well-being by weakening the adverse association between caregivers' stress and children's emotional distress. Thus, addressing caregiver stress levels and allowing children an outlet to cope with challenges through pretend play could have crucial protective effects on early development and well-being during times of crisis.

Pretending with realistic and fantastical stories facilitates executive function in 3-year-old children

Fictional stories can affect many aspects of children's behavior and cognition, yet little is known about how they might help or hinder children's executive function skills. The current study investigated the role of story content (fantasy or reality) and mode of engagement with the story (pretense or a non-pretense control) on children's inhibitory control, an important component of early executive function. A total of 60 3-year-olds were randomly assigned to hear a fantastical or realistic story and were encouraged to engage in either pretense or a non-pretense activity related to the story. They then completed the Less Is More task of inhibitory control. Story content had no impact on children's inhibitory control; children performed equally well after hearing a fantastical or realistic story. However, children who engaged in story-related pretend play showed greater inhibitory control than those who engaged in a non-pretense activity. We found no interaction between story content and play engagement type. These results held when controlling for baseline inhibitory control, receptive vocabulary, age, gender, affect, and propensity toward pretense. Therefore, mode of play engagement with a story was more important in promoting children's inhibitory control skills than the degree of realism in the story.

On Command Drug Delivery via Cell-Conveyed Phototherapeutics

Herein, the use of red blood cells (RBCs) as carriers of cytoplasmically interned phototherapeutic agents is described. Photolysis promotes drug release from the RBC carrier thereby providing the means to target specific diseased sites. This strategy is realized with a vitamin B12-taxane conjugate (B12-TAX), in which the drug is linked to the vitamin via a photolabile CoC bond. The conjugate is introduced into mouse RBCs (mRBCs) via a pore-forming/pore-resealing procedure and is cytoplasmically retained due to the membrane impermeability of B12. Photolysis separates the taxane from the B12 cytoplasmic anchor, enabling the drug to exit the RBC carrier. A covalently appended Cy5 antenna sensitizes the conjugate (Cy5-B12-TAX) to far red light, thereby circumventing the intense light absorbing properties of hemoglobin (350-600 nm). Microscopy and imaging flow cytometry reveal that Cy5-B12-TAX-loaded mRBCs act as drug carriers. Furthermore, intravital imaging of mice furnish a real time assessment of circulating phototherapeutic-loaded mRBCs as well as evidence of the targeted photorelease of the taxane upon photolysis. Histopathology confirms that drug release occurs in a well resolved spatiotemporal fashion. Finally, acoustic angiography is employed to assess the consequences of taxane release at the tumor site in Nu/Nu-tumor-bearing mice.

Experimental Paradigm for Measuring the Effects of Self-distancing in Young Children

Self-distancing (i.e., creating mental distance between the self and a stimulus by adopting a less egocentric perspective) has been studied as a way to improve adolescents' and adults' emotion regulation. These studies instruct adolescents and adults to use visual imagery or language to create distance from the self before engaging in self-regulation tasks and when thinking about past and future events. For example, adults are asked to recall past, negative emotional experiences from either a first-person perspective (no distance) or a third-person perspective (self-distanced). These studies show that a self-distanced perspective allows adults to cope more adaptively when recalling negative feelings. However, the self-distancing paradigm used with adults was not developmentally appropriate for young children. This modified self-distancing paradigm involves instructing children to think about their thoughts, feelings, and actions from different perspectives that vary in their distance from the self while completing a self-regulation task. The paradigm involves randomly assigning children to use one of three perspectives: self-immersed, third-person, or exemplar. In the self-immersed condition, children are asked to think about themselves using the first-person perspective (e.g., "How am I feeling?") and no distance is created from the self. In the third-person condition, children are asked to create distance from the self by using the third-person perspective (e.g., "How is [child's name] feeling?"). In the exemplar condition, the greatest distance from the self is created by asking children to pretend to be a media character and to think about that character's thoughts and feelings (e.g., "How is Batman feeling?"). Studies using the self-distancing paradigm with 4-6-year-olds have found that as the amount of distance from the self increases (self-immersed < third-person < exemplar), children perform better on self-regulation tasks. These findings suggest that the strategies implemented in the self-distancing protocol may be useful to include in self-regulation interventions for young children.

Focusing on the future from afar: Self-distancing from future stressors facilitates adaptive coping

Prior research indicates that visual self-distancing enhances adaptive self-reflection about negative past events (Kross & Ayduk, 2011). However, whether this process is similarly useful when people reflect on anxiety-provoking future negative experiences, and if so, whether a similar set of mechanisms underlie its benefits in this context, is unknown. Here we addressed these questions using a combination of experimental and individual difference methods with adults and adolescents (total N = 2,344). In Studies 1 and 2, spontaneous self-distancing predicted less anxious emotional reactivity among adults and adolescents. This effect was mediated by differences in how vividly participants imagined a future anxiety-provoking event. Study 3 provided causal evidence in an adult sample: Adopting a self-distanced (vs. self-immersed) perspective when reflecting on a future stressor led to lower levels of anxiety as well as lower imagery vividness. Consistent with Studies 1 and 2, reductions in imagery vividness mediated the emotion regulatory benefits of self-distancing. A meta-analysis of all three studies further confirmed these findings across samples. Thus, the current studies extend previous research on the benefits of self-distancing to future stressors. In addition, they highlight a novel mechanism for this relation: imagery vividness. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

A Stitch in Time: Strategic Self-Control in High School and College Students

A growing body of research indicates that self-control is critical to academic success. Surprisingly little is known, however, about the diverse strategies students use to implement self-control or how well these strategies work. To address these issues, we conducted a naturalistic investigation of self-control strategies (Study 1) and two field experiments (Studies 2 and 3). In Study 1, high school students described the strategies they use to manage interpersonal conflicts, get academic work done, eat healthfully, and manage other everyday self-control challenges. The majority of strategies in these self-nominated incidents as well as in three hypothetical academic scenarios (e.g., studying instead of texting friends) were reliably classified using the process model of self-control. As predicted by the process model, students rated strategies deployed early in the impulse-generation process (situation selection, situation modification) as being dramatically more effective than strategies deployed later (attentional deployment, cognitive change, response modulation). In Study 2, high school students randomly assigned to implement situation modification were more likely to meet their academic goals during the following week than students assigned either to implement response modulation or no strategy at all. In Study 3, college students randomly assigned to implement situation modification were also more successful in meeting their academic goals, and this effect was partially mediated by decreased feelings of temptation throughout the week. Collectively, these findings suggest that students might benefit from learning to initiate self-control when their impulses are still nascent.

Spontaneous Self-Distancing and Adaptive Self-Reflection Across Adolescence

Experiments performed primarily with adults show that self-distancing facilitates adaptive self-reflection. However, no research has investigated whether adolescents spontaneously engage in this process or whether doing so is linked to adaptive outcomes. In this study, 226 African American adolescents, aged 11-20, reflected on an anger-related interpersonal experience. As expected, spontaneous self-distancing during reflection predicted lower levels of emotional reactivity by leading adolescents to reconstrue (rather than recount) their experience and blame their partner less. Moreover, the inverse relation between self-distancing and emotional reactivity strengthened with age. These findings highlight the role that self-distancing plays in fostering adaptive self-reflection in adolescence, and begin to elucidate the role that development plays in enhancing the benefits of engaging in this process.

Safe handling of cytotoxics: guideline recommendations

BACKGROUND

This evidence-based practice guideline was developed to update and address new issues in the handling of cytotoxics, including the use of oral cytotoxics; the selection and use of personal protective equipment; and treatment in diverse settings, including the home setting.

METHODS

The guideline was developed primarily from an adaptation and endorsement of an existing guideline and from three systematic reviews. Before publication, the guideline underwent a series of peer and external reviews to gather feedback. All comments were addressed, and the guideline was amended when required. The guideline applies to health care workers who could come into contact with cytotoxic drugs at any point in the medication circuit. The intended users are hospital administrators, educators, and managers; occupational health and safety services; and pharmacy and health care workers.

RESULTS

The recommendations represent a reasonable and practical set of procedures that the intended users of this guideline should implement to minimize opportunities for accidental exposure. They are not limited to just the point of care; they cover the entire chain of cytotoxics handling from the time such agents enter the institution until they leave in the patient or as waste.

CONCLUSIONS

Reducing the likelihood of accidental exposure to cytotoxic agents within the medication circuit is the main objective of this evidenced-based guideline. The recommendations differ slightly from earlier guidelines because of the availability of new evidence.

The Academic Diligence Task (ADT): Assessing Individual Differences in Effort on Tedious but Important Schoolwork

The current study reports on the development and validation of the Academic Diligence Task (ADT), designed to assess the tendency to expend effort on academic tasks which are tedious in the moment but valued in the long-term. In this novel online task, students allocate their time between solving simple math problems (framed as beneficial for problem solving skills) and, alternatively, playing Tetris or watching entertaining videos. Using a large sample of high school seniors (N = 921), the ADT demonstrated convergent validity with self-report ratings of Big Five conscientiousness and its facets, self-control and grit, as well as discriminant validity from theoretically unrelated constructs, such as Big Five extraversion, openness, and emotional stability, test anxiety, life satisfaction, and positive and negative affect. The ADT also demonstrated incremental predictive validity for objectively measured GPA, standardized math and reading achievement test scores, high school graduation, and college enrollment, over and beyond demographics and intelligence. Collectively, findings suggest the feasibility of online behavioral measures to assess noncognitive individual differences that predict academic outcomes.

A Behind-the-Scenes Guide to School-Based Research

Schools are an important context for both basic and applied scientific research. Unlike the laboratory, however, the physical and social conditions of schools are not under the exclusive control of scientists. In this article, we liken collecting data in schools to putting on a theatrical production. We begin by describing the large cast of characters whose collaborative efforts make school-based research possible. Next, we address the critics, including the university Institutional Review Board (IRB) and school administrators, whose feedback often improves the final study design. We then turn our attention to set building, stage directions, and rehearsals - key steps in the iterative process of refining study procedures. We end with a discussion of the day of data collection itself and activities that take place after the curtain drops. Throughout, we make recommendations based on our recent experience collecting data at several high schools. All the world's a stage~William Shakespeare, As You Like It, 2.7.139.

Evidence for a relation between executive function and pretense representation in preschool children

Several theoretical formulations suggest a relation between children's pretense and executive function (EF) skills. However, there is little empirical evidence for a correlation between these constructs in early development. Preschool children (N = 104; M age = 4-0) were given batteries of EF and pretense representation measures, as well as verbal, memory, and appearance-reality control tasks. Confirmatory factor analysis revealed two separable but overlapping aspects of EF (Conflict and Delay). EF was significantly related to pretense after accounting for all controls. Understanding the pretend-reality distinction was strongly related to Conflict EF, whereas performing pretend actions was more strongly related to Delay EF. These results, although correlational, are consistent with the claim that EF skills are implicated in pretense, such as inhibiting reality and flexibly manipulating dual representations, and offer a potential mechanism by which pretend play interventions may enhance childhood EF.

Hyperhomocysteinemia is detrimental to pregnancy in mice and is associated with preterm birth

Elevated levels of homocysteine produce detrimental effects in humans but its role in preterm birth is not known. Here we used a mouse model of hyperhomocysteinemia to examine the relevance of homocysteine to preterm birth. The mouse carries a heterozygous deletion of cystathionine β-synthase (Cbs(+/-)). Gestational period was monitored in wild type and Cbs(+/-) female mice. Mouse uterine and placental tissues, human primary trophoblast cells, and human myometrial and placental cell lines were used to determine the influence of homocysteine on expression of specific genes in vitro. The activity of BKCa channel in the myometrial cell line was monitored using the patch-clamp technique. We found that hyperhomocysteinemia had detrimental effects on pregnancy and induced preterm birth in mice. Homocysteine increased the expression of oxytocin receptor and Cox-2 as well as PGE2 production in uterus and placenta, and initiated premature uterine contraction. A Cox-2 inhibitor reversed these effects. Gpr109a, a receptor for niacin, induced Cox-2 in uterus. Homocysteine upregulated GPR109A and suppressed BKCa channel activity in human myometrial cells. Deletion of Gpr109a in Cbs(+/-) mice reversed premature birth. We conclude that hyperhomocysteinemia causes preterm birth in mice through upregulation of the Gpr109a/Cox-2/PGE2 axis and that pharmacological blockade of Gpr109a may have potential in prevention of preterm birth.

Optimizing the design of preprinted orders for ambulatory chemotherapy: combining oncology, human factors, and graphic design

PURPOSE

To establish a set of guidelines for developing ambulatory chemotherapy preprinted orders.

METHODS

Multiple methods were used to develop the preprinted order guidelines. These included (A) a comprehensive literature review and an environmental scan; (B) analyses of field study observations and incident reports; (C) critical review of evidence from the literature and the field study observation analyses; (D) review of the draft guidelines by a clinical advisory group; and (E) collaboration with graphic designers to develop sample preprinted orders, refine the design guidelines, and format the resulting content.

RESULTS

The Guidelines for Developing Ambulatory Chemotherapy Preprinted Orders, which consist of guidance on the design process, content, and graphic design elements of ambulatory chemotherapy preprinted orders, have been established.

CONCLUSION

Health care is a safety critical, dynamic, and complex sociotechnical system. Identifying safety risks in such a system and effectively addressing them often require the expertise of multiple disciplines. This study illustrates how human factors professionals, clinicians, and designers can leverage each other's expertise to uncover commonly overlooked patient safety hazards and to provide health care professionals with innovative, practical, and user-centered tools to minimize those hazards.

Checking it twice: an evaluation of checklists for detecting medication errors at the bedside using a chemotherapy model

Objective

To determine what components of a checklist contribute to effective detection of medication errors at the bedside.

Design

High-fidelity simulation study of outpatient chemotherapy administration.

Setting

Usability laboratory.

Participants

Nurses from an outpatient chemotherapy unit, who used two different checklists to identify four categories of medication administration errors.

Main outcome measures

Rates of specified types of errors related to medication administration.

Results

As few as 0% and as many as 90% of each type of error were detected. Error detection varied as a function of error type and checklist used. Specific step-by-step instructions were more effective than abstract general reminders in helping nurses to detect errors. Adding a specific instruction to check the patient's identification improved error detection in this category by 65 percentage points. Matching the sequence of items on the checklist with nurses' workflow had a positive impact on the ease of use and efficiency of the checklist.

Conclusions

Checklists designed with explicit step-by-step instructions are useful for detecting specific errors when a care provider is required to perform a long series of mechanistic tasks under a high cognitive load. Further research is needed to determine how best to assist clinicians in switching between mechanistic tasks and abstract clinical problem solving.

Association between migraine, anxiety and depression

Logistic regression was used to evaluate the relationship between self-reported medical diagnosis of migraine, self-reported depressive symptomology (RDS) and self-reported anxious symptomology (RAS) in the National Health Interview Survey ( n = 30 852). Semipartial squared correlations evaluated the population-level variability between RDS, RAS and migraine impairment. Migraine prevalence was 15.2% (overall), 20.5% (women) and 9.4% (men). Migraine risk was higher in participants with RAS [odds ratio (OR) 2.30, 95% confidence interval (CI) 2.09, 2.52), with RDS (OR 2.23, 95% CI 1.93, 2.58), who smoked (OR 1.19, 95% CI 1.09, 1.30), or who consulted a mental health provider (OR 1.45, 95% CI 1.27, 1.65). Although migraine risk was increased in both women (OR 1.93) and men (OR 2.42) with RAS ( P < 0.001), men with RAS had a higher migraine risk than did women with RAS ( P < 0.001). Only 7% of the variability in migraine impairment (population level) was predicted by variability in RDS and/or RAS.

Two Epstein-Barr virus (EBV) oncoproteins cooperate to repress expression of the proapoptotic tumour-suppressor Bim: clues to the pathogenesis of Burkitt's lymphoma

Epstein-Barr virus (EBV) contributes to the development of several human cancers including the endemic form of Burkitt's lymphoma (BL). In culture, EBV induces the continuous proliferation of primary B cells as lymphoblastoid cell lines (LCLs) and if EBV-negative BL-derived cells are infected with EBV, latency-associated viral factors confer resistance to various inducers of apoptosis. Nuclear proteins EBNA3A and EBNA3C (but not EBNA3B) are necessary to establish LCLs and their expression may be involved in the resistance of BL cells to cytotoxic agents. We have therefore created recombinant EBVs from which each of the EBNA3 genes has been independently deleted, and revertant viruses in which the genes have been re-introduced into the viral genome. Infection of EBV-negative BL cells with this panel of EBVs and challenge with various cytotoxic drugs showed that EBNA3A and EBNA3C cooperate as the main determinants of both drug resistance and the downregulation of the proapoptotic Bcl-2-family member Bcl-2-interacting mediator of cell death (Bim). The regulation of Bim is predominantly at the level of RNA, with little evidence of post-translational Bim stabilization by EBV. In the absence of Bim, EBNA3A and EBNA3C appear to provide no survival advantage. The level of Bim is a critical regulator of B cell survival and reduced expression is a major determinant of lymphoproliferative disease in mice and humans; moreover, Bim is uniquely important in the pathogenesis of BL. By targeting this tumour-suppressor for repression, EBV significantly increases the likelihood of B lymphomagenesis in general, and BL in particular. Our results may also explain the selection pressure that gives rise to a subset of BL that retain expression of the EBNA3 proteins.

Absence of human papillomavirus in esophageal carcinomas from southwestern Kenya

Esophageal squamous cell cancer is highly prevalent in south-western Kenya. The role of human papillomavirus (HPV) in esophageal cancers from this region was evaluated. Biopsies of 29 esophageal squamous cell cancers were assayed for HPV DNA sequences by reverse line blot polymerase chain reaction, using 27 HPV type-specific probes. Viral sequences were found in none of the specimens. These results suggest the HPV is unlikely to be an etiologic factor for esophageal squamous cell cancers in this region.

Oxidative activation of acylguanidine prodrugs: intestinal presystemic activation in rats limits absorption and can be inhibited by co-administration of ketoconazole

1. The disposition of acyl prodrugs was studied to improve the delivery of a guanidine-containing parent compound with poor membrane permeability and poor absorption. 2. The prodrugs were evaluated in vitro and in vivo for conversion to drug. Prodrugs were evaluated for hydrolytic or oxidative bioactivation in intestinal homogenate and rat liver S9 or microsomes. The disposition of the prodrugs in vivo was monitored in bile duct-cannulated rats. 3. Compounds with n-alkylacyl groups were efficiently bioactivated, but were hydrolysed before absorption. 4. Hydrolytic bioactivation could be blocked in vitro by branching in the alkyl chain. These compounds showed modest improvements in absorption, despite favourable permeability. Experiments with liver microsomes demonstrated efficient NADPH-dependent oxidative bioactivation, which was proposed to occur through a CYP-mediated side chain oxidation followed by cyclization and release of parent compound. Ketoconazole co-administration yielded approximately a twofold increase in absorption. 5. The hydrolytically stable prodrugs were successful in increasing absorption of parent drug and were efficiently bioactivated, but they did not yield increased systemic levels of drug.

Sorption and degradation characteristics of phosmet in two contrasting Australian soils

The organophosphate insecticide phosmet [phosphorodithioic acid, s-((1,3-dihydro-1,3-dioxo-2H-isoindol-2yl)methyl), o,o-dimethyl ester] is used to control red-legged earth mites (Halotydeus destructor), lucerne flea (Sminthurus viridis), and Oriental fruit moth (Cydia molesta) in horticulture and vegetable growing. This study was undertaken with two soils of contrasting properties to determine the extent to which sorption and degradation of the insecticide might influence its potential to leach from soil into receiving waters. Two soils were used: a highly organic, oxidic clay soil (Ferrosol) and a sandy soil low in organic matter (Podosol), sampled to 0.3 m depth. The extent of sorption and decomposition rate of a phosmet commercial formulation were measured in laboratory experiments. Sorption followed a Freundlich isotherm at all depths. The Freundlich coefficient K was significantly correlated (p = 0.005) with organic C content in the Podosol, and significantly correlated (p = 0.005) with organic C and clay content in the Ferrosol. K was highest (48.8 L kg-1) in the 0- to 0.05-m depth of the Ferrosol, but lowest (1.0 L kg-1) at this depth in the Podosol. Degradation followed first-order kinetics, with the phosmet half-life ranging from 14 h (0-0.05 m depth) to 187 h (0.2-0.3 m depth) in the Ferrosol. The half-life was much longer in the sandy Podosol, ranging from 462 to 866 h, and did not change significantly with depth. Soil organic C and to a lesser degree clay content influenced phosmet sorption and degradation, but the interaction was complex and possibly affected by co-solvents present in the commercial formulation.

Effect of posterior capsular repair on early dislocation in primary total hip replacement

Formal repair of the posterior capsule and short external rotator tendons has been described as a surgical approach to reduce the incidence of posterior dislocation after posterolateral surgical approach to primary total hip replacement. The purpose of the current study was to compare the incidence of early posterior dislocation (within the first 6 months after surgery) using a complete posterior capsulectomy versus a formal posterior capsular repair. In patients with a complete posterior capsulectomy, 52 of 1078 primary total hip replacements (4.8%) had an early posterior dislocation. In patients with posterior capsular repair, three of 437 primary total hip replacements (0.7%) had an early posterior dislocation. This difference was statistically significant. The only complication in the capsular repair group was an avulsion fracture of the greater trochanter in four of 437 total hip replacements (0.9%).

Direct simultaneous analysis of plasma samples for a drug discovery compound and its hydroxyl metabolite using mixed-function column liquid chromatography-tandem mass spectrometry

A polymer-coated mixed-function (PCMF) column was evaluated for direct plasma injection for the simultaneous determination of a drug candidate and its hydroxyl metabolite by high-performance liquid chromatography (HPLC) with tandem mass spectrometry (MS-MS) in support of pharmacokinetic studies. Each diluted monkey plasma sample containing internal standard was directly injected on to the PCMF column for sample clean-up, enrichment and chromatographic separation. The proteins and macromolecules were first eluted from the column while the drug molecules were retained on the bonded hydrophobic phase. The analytes retained on the column were then eluted with a strong mobile phase using a gradient separation technique at a constant flow rate of 1.0 ml min(-1). When not diverted, the column effluent was connected either to the atmospheric pressure chemical ionization (APCI) source or the electrospray ionization (ESI) source as part of the mass spectrometer system used for quantification. The calibration curve was linear over the range 5-2500 ng ml(-1) for both analytes. The retention times for the analytes and the internal standard were both consistent and no column deterioration was observed for at least 500 injections. The recovery through the column and reproducibility of the dosed compound and its hydroxyl metabolite in monkey plasma samples were > 90% (RSD < 6%). The total analysis time was < 8 min per sample. The analytical results obtained by the proposed direct plasma injection method were in good agreement with those obtained by the conventional LC-MS-MS method.

Sequences adjacent to oriP improve the persistence of Epstein-Barr virus-based episomes in B cells

Epstein-Barr virus (EBV) oriP and the EBV nuclear antigen 1 (EBNA-1) protein allow persistence of EBV-based episomes. A nuclear matrix attachment region (MAR) spans oriP and the adjacent region of the EBV genome containing the EBV-expressed RNAs. Here, we show that episomes with the MAR are retained significantly more efficiently in EBV-positive B cells than episomes containing oriP alone.

Epoxyeicosatrienoic acid-induced relaxation is impaired in insulin resistance

We assessed the effect of epoxyeicosatrienoic acids (EETs) in intact mesenteric arteries and Ca(2+)-activated K(+) (BK(Ca)) channels of isolated vascular smooth muscle cells from control and insulin-resistant (IR) rats. The response to 11,12-EET and 14,15-EET was assessed in small mesenteric arteries from control and IR rats in vitro. Mechanistic studies were performed in endothelium intact or denuded arteries and in the presence of pharmacological inhibitors. Moreover, EET-induced activation of the BK(Ca) channel was assessed in myocytes in both the cell-attached and the inside-out (I/O) patch-clamp configurations. In control arteries, both EET isomers induced relaxation. Relaxation was impaired by endothelium denudation, N(omega)-nitro-L-arginine, or iberiotoxin (IBTX), whereas it was abolished by IBTX + apamin or charybdotoxin + apamin. In contrast, the EETs did not relax IR arteries. In control myocytes, the EETs increased BK(Ca) activity in both configurations. Conversely, in the cell-attached mode, EETs had no effect on BK(Ca) channel activity in IR myocytes, whereas in the I/O configuration, BK(Ca) channel activity was enhanced. EETs induce relaxation in small mesenteric arteries from control rats through K(Ca) channels. In contrast, arteries from IR rats do not relax to the EETs. Patch-clamp studies suggest impaired relaxation is due to altered regulatory mechanisms of the BK(Ca) channel.

Testosterone relaxes coronary arteries by opening the large-conductance, calcium-activated potassium channel

Cardiovascular diseases are often considered to be a predominantly male health problem, and it has been suggested that testosterone exerts deleterious effects on cardiovascular function; however, few experimental studies support this suggestion. Moreover, the cellular and molecular mechanism(s) underlying vascular responses to testosterone is unknown. The present study has investigated the acute effects of testosterone on porcine coronary artery smooth muscle at the tissue and cellular levels. Contractile studies demonstrated that testosterone or dihydrotestosterone (a nonaromatizable metabolite) relaxed these arteries by an endothelium-independent mechanism involving potassium efflux. Direct evidence from patch-clamp studies confirmed that testosterone opened K(+) channels in single coronary myocytes, and further analysis identified this protein as the large-conductance, calcium- and voltage-activated potassium (BK(Ca)) channel. Moreover, inhibiting BK(Ca) channel activity significantly attenuated testosterone-induced coronary relaxation. These findings indicate that testosterone relaxes porcine coronary arteries predominantly by opening BK(Ca) channels in coronary myocytes, and this response may be associated with accumulation of cGMP. This novel mechanism may provide a better understanding of testosterone-induced vasorelaxation reported in recent experimental and early clinical studies.

Pharmacokinetic theory of cassette dosing in drug discovery screening

Cassette dosing is a procedure for higher-throughput screening in drug discovery to rapidly assess pharmacokinetics of large numbers of candidate compounds. In this procedure, multiple compounds are administered simultaneously to a single animal. Blood samples are collected, and the plasma samples obtained are analyzed by means of an assay method such as liquid chromatography coupled to tandem mass spectrometry that permits concurrent assay of many compounds in a single sample. Consequently, the pharmacokinetics of multiple compounds can be assessed rapidly with a small number of experimental animals and with shortened assay times. However, coadministration of multiple compounds may result in pharmacokinetic drug-drug interactions. This paper describes a pharmacokinetic description for cassette dosing derived from pharmacokinetic theory. The most important finding from this theoretical treatment is that the potential for drug-drug interactions leading to altered clearances of coadministered drugs depends on both the relative K(M) values for the metabolic enzymes and the total number of drugs coadministered. However, the theory predicts that the potential for drug-drug interactions is only a weak function of the dose size. Finally, it is also shown that including a benchmark compound within the set of coadministered compounds cannot ensure the detection of errors due to drug-drug interactions. Thus, neither the absolute values of pharmacokinetic parameters nor the rank order obtained from cassette dosing can be accepted without independent confirmation. These theoretical predictions are evaluated with data taken from the literature.

Resection arthroplasty for nonseptic failure of total hip arthroplasty

Although resection arthroplasty is a well-recognized salvage procedure for septic total hip arthroplasty, the nonseptic complications of total hip arthroplasty are customarily handled by revision and replacement of a new total hip implant. Some of the severe forms of failure of total hip arthroplasty in the absence of infection may require resection arthroplasty. The indication is massive loss of available bone stock for the revision operation. This may result from technical errors or progressive and extensive destruction of bone associated with loosened components. Concern for this outcome is important for assessing the probabilities of long-term success of the use of total hip arthroplasty in young patients.

Esophageal stent placement without fluoroscopy

BACKGROUND

Access to fluoroscopic equipment is limited in some regions where esophageal cancer is common. This report describes a simple method for placement of expandable esophageal stents without fluoroscopy.

METHODS

Patients with dysphagia due to unresectable esophageal cancer underwent esophageal stent placement under endoscopic control alone. A colored mark on the stent delivery catheter was used to properly position the undeployed stent with respect to the proximal end of the tumor.

RESULTS

Stent placement was attempted in 70 patients and was successful in every case. There were no immediate complications of stent placement. Mean dysphagia score decreased from 3.3 before stent placement to 0.5 at follow-up. There was a trend toward lower dysphagia scores in patients who received coated stents.

CONCLUSION

Expandable esophageal stents can be accurately and safely placed under direct endoscopic control, without fluoroscopy.

Angiotensin II relaxes microvessels via the AT(2) receptor and Ca(2+)-activated K(+) (BK(Ca)) channels

Angiotensin II (Ang II) is one of the most potent vasoconstrictor substances, yet paradoxically, Ang II may dilate certain vascular beds via an undefined mechanism. Ang II-induced vasoconstriction is mediated by the AT(1) receptor, whereas the relative expression and functional importance of the AT(2) receptor in regulating vascular resistance and blood pressure are unknown. We now report that Ang II induces relaxation of mesenteric microvessels and that this vasodilatory response was unaffected by losartan, an AT(1) receptor antagonist, but was inhibited by PD123,319, a selective antagonist of AT(2) receptors. In addition, reverse transcriptase-polymerase chain reaction studies revealed high amounts of AT(2) receptor mRNA in smooth muscle from these same microvessels. Ang II-induced relaxation was inhibited by either tetraethylammonium or iberiotoxin, suggesting involvement of the large-conductance, calcium- and voltage-activated potassium (BK(Ca)) channel. Subsequent whole-cell and single-channel patch-clamp studies on single myocytes demonstrated that Ang II increases the activity of BK(Ca) channels. As in our tissue studies, the effect of Ang II on BK(Ca) channels was inhibited by PD123,319, but not by losartan. In light of these consistent findings from tissue physiology, molecular studies, and cellular/molecular physiology, we conclude that Ang II relaxes microvessels via stimulation of the AT(2) receptor with subsequent opening of BK(Ca) channels, leading to membrane repolarization and vasodilation. These findings provide evidence for a novel endothelium-independent vasodilatory effect of Ang II.

Cassette-accelerated rapid rat screen: a systematic procedure for the dosing and liquid chromatography/atmospheric pressure ionization tandem mass spectrometric analysis of new chemical entities as part of new drug discovery

This report addresses the continuing need for increased throughput in the evaluation of new chemical entities (NCEs) in terms of their pharmacokinetic (PK) parameters by describing an alternative procedure for increasing the throughput of the in vivo screening of NCEs in the oral rat PK model. The new approach is called "cassette-accelerated rapid rat screen" (CARRS). In this assay, NCEs are dosed individually (n = 2 rats/compound) in batches of six compounds per set. The assay makes use of a semi-automated protein precipitation procedure for sample preparation in a 96-well plate format. The liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) assay is also streamlined by analyzing the samples as "cassettes of six". Using this new approach, a threefold increase in throughput was achieved over the previously reported "rapid rat screen".

Stable correction of a genetic deficiency in human cells by an episome carrying a 115 kb genomic transgene

Persistent expression of a transgene at therapeutic levels is required for successful gene therapy, but many small vectors with heterologous promoters are prone to vector loss and transcriptional silencing. The delivery of genomic DNA would enable genes to be transferred as complete loci, including regulatory sequences, introns, and native promoter elements. These elements may be critical to ensure prolonged, regulated, and tissue-specific transgene expression. Many studies point to considerable advantages to be gained by using complete genomic loci in gene expression. Large-insert vectors incorporating elements of the bacterial artificial chromosome (BAC) cloning system, and the episomal maintenance mechanisms of Epstein-Barr virus (EBV), can shuttle between bacteria and mammalian cells, allowing large genomic loci to be manipulated conveniently. We now demonstrate the potential utility of such vectors by stably correcting a human genetic deficiency in vitro. When the complete hypoxanthine phosphoribosyltransferase (HPRT) locus of 115 kilobases (kb) was introduced into deficient human cells, the transgene was both maintained as an episome and expressed stably for six months in rapidly dividing cell cultures. The results demonstrate for the first time that gene expression from an episomal genomic transgene can correct a cell culture disease phenotype for a prolonged period.

Diazepam, gamma-aminobutyric acid, and progesterone open K(+) channels in myocytes from coronary arteries

Benzodiazepines enhance coronary blood flow and lower blood pressure, but the cellular basis of this action remains unclear. The present study now demonstrates a direct effect of diazepam, gamma-aminobutyric acid (GABA), and progesterone on the large conductance, Ca(2+)- and voltage-activated K(+) channel (BK(Ca)) in single myocytes isolated from porcine coronary arteries. These GABA receptor agonists significantly increased whole-cell (perforated patch) K(+) currents and stimulated the activity of single BK(Ca) channels in cell-attached patches dramatically. This effect is not mediated via cyclic AMP or cyclic GMP, but involves stimulation of Ca(2+) influx in response to activation of a bicuculline-sensitive GABA(A)-like receptor. We propose that localized, subsarcolemmal increases in Ca(2+) levels open BK(Ca) channels, thereby promoting K(+) efflux, membrane repolarization, and coronary relaxation. This transduction pathway can now account, at least in part, for the direct vasodilatory effects of diazepam, progesterone, and GABA.

High-throughput screening in drug metabolism and pharmacokinetic support of drug discovery

The application of rapid methods currently used for screening discovery drug candidates for metabolism and pharmacokinetic characteristics is discussed. General considerations are given for screening in this context, including the criteria for good screens, the use of counterscreens, the proper sequencing of screens, ambiguity in the interpretation of results, strategies for false positives and negatives, and the special difficulties encountered in drug metabolism and pharmacokinetic screening. Detailed descriptions of the present status of screening are provided for absorption potential, blood-brain barrier penetration, inhibition and induction of cytochrome P450, pharmacokinetics, biotransformation, and computer modeling. Although none of the systems currently employed for drug metabolism and pharmacokinetic screening can be considered truly high-throughput, several of them are rapid enough to be a practical part of the screening paradigm for modern, fast-moving discovery programs.

H(2)O(2) opens BK(Ca) channels via the PLA(2)-arachidonic acid signaling cascade in coronary artery smooth muscle

H(2)O(2) is a reactive oxygen species that contracts or relaxes vascular smooth muscle, but the molecular basis of these effects remains obscure. We previously demonstrated that H(2)O(2) opens the large-conductance, calcium- and voltage-activated (BK(Ca)) potassium channel of coronary myocytes (2) and now report physiological and biochemical evidence that the effect of H(2)O(2) on coronary smooth muscle involves the phospholipase A(2) (PLA(2))/arachidonic acid (AA) signaling cascades. H(2)O(2) stimulation of BK(Ca) channel activity was inhibited by arachidonyl trifluoromethyl ketone, an inhibitor of cytosolic PLA(2). Furthermore, H(2)O(2) stimulated release of [(3)H]AA from coronary myocytes, and exogenous AA mimicked the effect of H(2)O(2) on BK(Ca) channels. Inhibitors of protein kinase C activity attenuated the effect of H(2)O(2) on BK(Ca) channels, [(3)H]AA release, or intact coronary arteries. In addition, the effect of H(2)O(2) or AA on BK(Ca) channels was inhibited by blockers of lipoxygenase metabolism. In contrast, inhibitors of cyclooxygenase or cytochrome P-450 had no effect. We propose that H(2)O(2) relaxes coronary arteries by stimulating BK(Ca) channels via the PLA(2)/AA signaling cascade and that lipoxygenase metabolites mediate this response.

Calcium-activated potassium channels and nitric oxide coregulate estrogen-induced vasodilation

Nitric oxide synthase (NOS) contributes to estradiol-17beta (E(2)beta)-induced uterine vasodilation, but additional mechanisms are involved, and the cellular pathways remain unclear. We determined if 1) uterine artery myocytes express potassium channels, 2) E(2)beta activates these channels, and 3) channel blockade plus NOS inhibition alters E(2)beta-induced uterine vasodilation. Studies of cell-attached patches identified a 107 +/- 7 pS calcium-dependent potassium channel (BK(Ca)) in uterine artery myocytes that rapidly increased single-channel open probability 70-fold (P < 0.05) after exposure to 100 nM E(2)beta through an apparent cGMP-dependent mechanism. In ovariectomized nonpregnant ewes (n = 11) with uterine artery flow probes and catheters, local BK(Ca) blockade with tetraethylammonium (TEA; 0.05-0.6 mM) dose dependently inhibited E(2)beta-induced uterine vasodilation (n = 37, R = 0.77, P < 0.0001), with maximum inhibition averaging 67 +/- 11%. Mean arterial pressure (MAP) and E(2)beta-induced increases (P </= 0.001) in heart rate (13%) and contralateral uterine blood flow (UBF, approximately 5-fold) were unaffected. Local NOS inhibition plus BK(Ca) blockade, using submaximal doses of nitro-L-arginine methyl ester (5 mg/ml) and TEA (0.3 mM), did not alter basal UBF but completely inhibited ipsilateral E(2)beta-induced uterine vasodilation without affecting MAP and E(2)beta-induced increases in contralateral UBF and heart rate. Acute E(2)beta-mediated uterine vasodilation involves rapid activation of uterine artery BK(Ca) and NOS, and the pathway for their interaction appears to include activation of guanylyl cyclase.

cAMP-dependent vasodilators cross-activate the cGMP-dependent protein kinase to stimulate BK(Ca) channel activity in coronary artery smooth muscle cells

cAMP-dependent vasodilators are used to treat a variety of cardiovascular disorders; however, the signal transduction pathways and effector mechanisms stimulated by these agents are not fully understood. In the present study we demonstrate that cAMP-stimulating agents enhance the activity of the large-conductance, calcium-activated potassium (BK(Ca)) channel in single myocytes from coronary arteries by "cross-activation" of the cGMP-dependent protein kinase (protein kinase G, PKG). Single-channel patch-clamp data revealed that 10 micromol/L isoproterenol, forskolin, or dopamine opens BK(Ca) channels in coronary myocytes and that this effect is attenuated by inhibitors of PKG (KT5823; Rp-8-pCPT-cGMPS), but not by inhibiting the cAMP-dependent protein kinase (protein kinase A, PKA). In addition, a membrane-permeable analog, CPT-cAMP, also opened BK(Ca) channels in these myocytes, and this effect was reversed by KT5823. Direct biochemical measurement confirmed that dopamine or forskolin stimulates PKG activity in coronary arteries but does not elevate cGMP. Finally, the stimulatory effect of cAMP on BK(Ca) channels was reconstituted in a cell-free, inside-out patch by addition of purified PKG activated by either cGMP or cAMP. In contrast, channel gating was unaffected by exposure to the purified catalytic subunit of PKA. In summary, findings from on-cell and cell-free patch-clamp experiments provide direct evidence that cAMP-dependent vasodilators open BK(Ca) channels in coronary myocytes by cross-activation of PKG (but not via PKA). Biochemical assay confirmed this cross-activation mechanism of cAMP action in these arteries. This signaling pathway is a novel mechanism for regulation of potassium channel activity in vascular smooth muscle and other cells.

Gender and ethnic differences in health behaviors and risk factors for coronary disease among urban teenagers: the PATH program

OBJECTIVE

To assess gender and ethnic differences among teenagers in heart health behaviors, risk factors for coronary heart disease (CHD), and cardiovascular fitness.

DESIGN

Observations consist of cross-sectional data collected prior to a school-based health promotion intervention program.

PARTICIPANTS

Teenage girls (N = 865) and boys (N = 497) from three New York City high schools. The ethnic composition of this sample was 20% Asian-American, 40% African-American, 25% Hispanic, and 15% white.

METHOD

Subjects were compared on the following: height, weight, body mass index, percentage body fat, total cholesterol, blood pressure, heart health knowledge, family history, socioeconomic status, dietary habits, smoking, physical activity, and estimated aerobic capacity. Differences were assessed with independent t tests, analysis of variance, and chi-square statistical techniques.

RESULTS

Compared with girls, boys were more active and had higher estimated aerobic capacity, higher systolic blood pressure, and better self-perception of health. Compared with boys, girls had higher cholesterol, percentage body fat, and heart health knowledge scores and ate fewer foods high in saturated fat, cholesterol, salt, and simple sugars. Among girls, African-Americans had the highest blood pressure, cholesterol, body mass index, and intake of foods high in saturated fat, cholesterol, and sugar. Among boys, Hispanics had the highest body mass index and percentage body fat and the lowest heart health knowledge scores. White girls and white boys were the most frequent smokers.

CONCLUSIONS

Poor health behaviors and risk factors for CHD occurred frequently among urban teenagers. In general, teenage girls had poorer health behaviors and a greater prevalence of risk factors than teenage boys, even though they scored better in heart health knowledge testing. Ethnic comparisons revealed poorer health behaviors and higher prevalence of risk factors in African-American and Hispanic teens compared with white and Asian-American teens. Results support the need for health promotion intervention among urban teenagers.

K-Cl cotransport in vascular smooth muscle and erythrocytes: possible implication in vasodilation

K-Cl cotransport, the electroneutral-coupled movement of K and Cl ions, plays an important role in regulatory volume decrease. We recently reported that nitrite, a nitric oxide derivative possessing potent vasodilation properties, stimulates K-Cl cotransport in low-K sheep red blood cells (LK SRBCs). We hypothesized that activation of vascular smooth muscle (VSM) K-Cl cotransport by vasodilators decreases VSM tension. Here we tested this hypothesis by comparing the effects of commonly used vasodilators, hydralazine (HYZ), sodium nitroprusside, isosorbide mononitrate, and pentaerythritol, on K-Cl cotransport in LK SRBCs and in primary cultures of rat VSM cells (VSMCs) and of HYZ-induced K-Cl cotransport activation on relaxation of isolated porcine coronary rings. K-Cl cotransport was measured as the Cl-dependent K efflux or Rb influx in the presence and absence of inhibitors for other K/Rb transport pathways. All vasodilators activated K-Cl cotransport in LK SRBCs and HYZ in VSMCs, and this activation was inhibited by calyculin and genistein, two inhibitors of K-Cl cotransport. KT-5823, a specific inhibitor of protein kinase G, abolished the sodium nitroprusside-stimulated K-Cl cotransport in LK SRBCs, suggesting involvement of the cGMP pathway in K-Cl cotransport activation. Hydralazine, in a dose-dependent manner, and sodium nitroprusside relaxed (independently of the endothelium) precontracted arteries when only K-Cl cotransport was operating and other pathways for K/Rb transport, including the Ca-activated K channel, were inhibited. Our findings suggest that K-Cl cotransport may be involved in vasodilation.

A novel transduction mechanism mediating dopamine-induced vascular relaxation: opening of BKCa channels by cyclic AMP-induced stimulation of the cyclic GMP-dependent protein kinase

Dopamine dilates the coronary, renal and other vascular beds; however, the signaling pathway underlying this effect is unclear. In this study the signal-transduction process mediating dopamine-induced relaxation of porcine coronary arteries was investigated in isolated vessels and single arterial myocytes. Dopamine-induced relaxation of arteries was mediated through the DA- receptor and involved K+ efflux, and subsequent patch-clamp studies demonstrated that either dopamine or fenoldopam, a selective DA-1 agonist, increased the opening probability of the large-conductance, calcium- and voltage-activated K+ (BKCa) channel in coronary myocytes. Moreover, blockade of this channel by iberiotoxin prevented dopamine-induced coronary relaxation. Dopamine stimulation of BKCa channels was completely prevented by a DA-1-receptor antagonist, but was unaffected by propranolol. Furthermore, inhibiting adenylyl cyclase activity prevented stimulation of BKCa channel activity, whereas chlorophenylthio (CPT)-cyclic adenosine monophosphate (AMP), a membrane-permeable analog of cyclic AMP, mimicked the effects of dopamine. Interestingly, inhibiting the cyclic AMP-dependent protein kinase (PKA) did not affect the response to dopamine, whereas dopamine-induced channel activity was completely blocked by inhibiting the activity of the cyclic guanosine monophosphate (GMP)-dependent protein kinase (PKG). These findings demonstrate that activation of DA-1 receptors causes stimulation of BKCa channel activity by a mechanism involving cyclic AMP-dependent stimulation of PKG, but not PKA, and further suggest that this cross-reactivity mediates dopamine-induced coronary vasodilation.

Clinical comparison of the midvastus and medial parapatellar surgical approaches

The medial parapatellar approach and the midvastus approach are the two most commonly used surgical approaches in total knee replacement. This study compared surgical and clinical parameters associated with both surgical approaches in primary total knee replacement. One hundred nine patients who underwent bilateral primary total knee replacements had a medial parapatellar approach to one knee and a midvastus approach to the opposite knee. The prosthetic design and physical therapy were identical in all 109 patients. The patients and physical therapists were blinded to the type of approach used on each knee. The comparison included the surgical parameters of difficulty of exposure, surgical time, incidence of lateral retinacular release, and total blood loss. The clinical parameters of pain, range of motion, ability to perform a straight leg raise, and complications were compared at 8 days, 6 weeks and 6 months. The comparison between the two surgical approaches showed a statistically significant difference in four parameters, all of which favored the midvastus approach. The patients who had the midvastus approach required fewer lateral retinacular releases, had less pain at 8 days, had less pain at 6 weeks, and had a higher incidence of ability to straight leg raise at 8 days. There was no statistical difference between the two surgical approaches in all other surgical and clinical parameters. There was no increased difficulty of exposure using the midvastus approach when compared with the medial parapatellar approach even in patients with severe varus or valgus deformities. Notably, all clinical parameters were equal at 6 months. From a clinical standpoint, the midvastus approach had an advantage over the medial parapatellar approach because the patients had significantly less pain and had the ability to straight leg raise at 8 days. Because the managed care environment dictates a shorter hospital stay, patients who have the midvastus surgical approach have less pain and earlier control of the operative leg, and may be discharged from the hospital earlier. However, the clinical results at 6 months based on the patient's pain relief, range of motion, and ability to straight legraise were identical between the two surgical approaches.

Resveratrol inhibits MAPK activity and nuclear translocation in coronary artery smooth muscle: reversal of endothelin-1 stimulatory effects

In porcine coronary arteries, short-term treatment with resveratrol (RSVL) substantially inhibited MAPK activity (IC50 = 37 microM); and immunoblot analyses revealed consistent reduction in the phosphorylation of ERK-1/-2, JNK-1 and p38, at active sites. Endothelin-1 (ET-1), a primary antecedent in coronary heart diseases, enhanced MAPK activity, phosphorylation and nuclear translocation in a concentration-responsive but RSVL-sensitive manner. RSVL had no effect on basal or forskolin-stimulated cAMP levels, a known downregulator of the MAPK cascade. Likewise, inhibition of MAPK by RSVL was not reversed by the estrogen receptor blockers tamoxifen and ICI-182,780. Conversely, RSVL remarkably attenuated basal and ET-1-evoked protein tyrosine phosphorylation. Because MAPKs promote smooth muscle proliferation and contraction, their current inhibition may contribute to the putative protection by RSVL against coronary heart diseases. These effects apparently do not involve interaction with estrogen receptors.