Rating Dyspnea and Pain: "No" is Not Always "Zero"

Nurses routinely assess pain in hospitalized patients; similar assessment of dyspnea is increasing. Most nurses start with a yes-no question when assessing pain or dyspnea; many record "no" as a zero rating, skipping the rating scale. We tested the hypothesis that recording "no" answers as "zero" fails to detect the symptoms that would have been detected with a rating scale. Nurses asked 60 patients yes-no questions about the presence of dyspnea and pain, then asked patients to rate the symptoms using a 0-10 scale. All "yes" answers were followed by a concordant rating (i.e., greater than zero). More than 25% of "no" answers were followed by a discordant rating (> zero). Documenting "no" as "zero" missed information potentially useful in care planning; patients who rate dyspnea above zero are at greater risk of adverse outcomes. This information can also provide opportunity to start a discussion with patients who may benefit from symptom management.

Triage Decisions Involving Pregnancy-Capable Patients: Educational Deficits and Emergency Nurses' Perceptions of Risk

BACKGROUND

In areas where obstetric services are not available, emergency departments often become the default for unplanned obstetric care, yet emergency nurses are not universally trained in the identification and treatment of obstetric emergencies. The purpose of this study was to explore emergency nurses' perception of acuity in the triage of pregnant or postpartum patients presenting to the emergency department with high-risk complaints and to identify facilitators and challenges to the accurate identification and treatment of these patients.

METHOD

A mixed-methods study was conducted using chart review data (N = 12,766) and focus group data (N = 39) from five emergency departments in the eastern United States.

RESULTS

In 86.5% of cases, pregnancy status was not documented. Ninety-four percent of pregnant patients with a systolic blood pressure over 140 mmHg were under-triaged. The overall theme of the qualitative data was acuity blindness, with identified barriers to assessment that included educational needs and triage processes and workflow issues.

CONCLUSION

There are significant knowledge deficits in the care of patients presenting with high-risk conditions associated with pregnancy. [J Contin Educ Nurs. 2021;52(1):21-29.].

'Scared to death' dyspnoea from the hospitalised patient's perspective

Because dyspnoea is seldom experienced by healthy people, it can be hard for clinicians and researchers to comprehend the patient’s experience. We collected patients’ descriptions of dyspnoea in their own words during a parent study in which 156 hospitalised patients completed a quantitative multidimensional dyspnoea questionnaire. These volunteered comments describe the severity and wide range of experiences associated with dyspnoea and its impacts on a patients’ life. They provide insights not conveyed by structured rating scales. We organised these comments into the most prominent themes, which included sensory experiences, emotional responses, self-blame and precipitating events. Patients often mentioned air hunger (‘Not being able to get air is the worst thing that could ever happen to you.’), anxiety, and fear (‘Scared. I thought the world was going to end, like in a box.’). Their value in patient care is suggested by one subject’s comment: ‘They should have doctors experience these symptoms, especially dyspnoea, so they understand what patients are going through.’ Patients’ own words can help to bridge this gap of understanding.

Intensive Care Nurses' Perceptions of Routine Dyspnea Assessment

BACKGROUND

Dyspnea (breathing discomfort) is commonly experienced by critically ill patients and at this time is not routinely assessed and documented. Intensive care unit nurses at the study institution recently instituted routine assessment and documentation of dyspnea in all patients able to report using a numeric scale ranging from 0 to 10.

OBJECTIVE

To assess nurses' perceptions of the utility of routine dyspnea measurement, patients' comprehension of assessment questions, and the impact on nursing practice and to gather nurses' suggestions for improvement.

METHODS

Data were obtained from interviews with intensive care unit nurses in small focus groups and an anonymous online survey randomly distributed to nurses representing all intensive care units.

RESULTS

Intensive care unit nurses affirmed the importance of routine dyspnea assessment and documentation. Before implementing the measurement tool, nurses often assessed for breathing discomfort in patients by using observed signs. Most nurses agreed that routine assessment can be used to predict patients' outcomes and improve patient-centered care. Nurses found the assessment tool easy to use and reported that it did not interfere with workflow. Nurses felt that patients were able to provide meaningful ratings of dyspnea, similar to ratings of pain, and often used patients' ratings in conjunction with observed physical signs to optimize patient care.

CONCLUSION

Our study shows that nurses understand the importance of routine dyspnea assessment and that the addition of a simple patient report scale can improve care delivery and does not add to the burden of work-flow.

Routine dyspnea assessment and documentation: Nurses' experience yields wide acceptance

Background

Dyspnea (breathing discomfort) is a common and distressing symptom. Routine assessment and documentation can improve management and relieve suffering. A major barrier to routine dyspnea documentation is the concern that it will have a deleterious effect on nursing workflow and that it will not be readily accepted by nurses. Nurses at our institution recently began to assess and document dyspnea on all medical-surgical patients upon admission and once per shift throughout their hospitalization. A year after dyspnea measurement was implemented we explored nurses’ approach to dyspnea assessment, their perception of patient response, and their perception of the utility and burden of dyspnea measurement.

Methods

We obtained feedback from nurses using a three-part assessment of practice: 1) a series of recorded focus group interviews with nurses, 2) a time-motion observation of nurses performing routine dyspnea and pain assessment, and 3) a randomized, anonymous on-line survey based, in part, on issues raised in focus groups.

Results

Ninety-four percent of the nurses surveyed reported administering the dyspnea assessment is “easy” or “very easy”. None of the nurses reported that assessing dyspnea negatively impacted workflow and many reported that it positively improved their practice by increasing their awareness. Our time-motion data showed dyspnea assessment and documentation takes well less than a minute. Nurses endorsed the importance of routine measurement and agreed that most patients were able to provide a meaningful rating of their dyspnea. Nurses found the patient report very useful, and used it in conjunction with observed signs to respond to changes in a patient’s condition.

Conclusions

In this study, we have demonstrated that routine dyspnea assessment and documentation was widely accepted by the nurses at our institution. Our nurses fully incorporated routine dyspnea assessment and documentation into their practice and felt that it improved patient-centered care.

Electronic supplementary material

The online version of this article (doi:10.1186/s12912-016-0196-9) contains supplementary material, which is available to authorized users.

Developing a Blood Conservation Program in Cardiac Surgery

The beneficial effects of blood transfusions have been described and widely accepted. Multiple factors, including shortages, costs, infectious risks, immunologic risks, and the risk/benefit ratio to the patient, have made the medical community reassess the guidelines for transfusion. Cardiac surgery presents a unique subset of patients, because intervention at multiple stages in the care of these patients is possible to decrease the need for transfusion. An algorithm for a cardiac surgery program was developed and a reassessment performed. Once it was seen that no detrimental effect on patient care occurred, the program was expanded, was enhanced, and subsequently has been offered to the rest of the health care system. This program has resulted in a decrease in cost while maintaining patient outcomes. The success of the program is believed to be a result of the multidisciplinary approach taken, with a commitment from all members of the blood reduction team being the key component of this success.

Evidence for a role of an intracardiac renin-angiotensin system in normal and failing hearts

Although substantial evidence of a cardiac RAS has been obtained in the past decade, a number of important questions remain unanswered. These include identification and localization of the cell types responsible for production of the system's components as well as the regulation of synthesis, storage, and secretion pathways for each component. Future studies, which will utilize tools of molecular biology that have become recently available (for example, transgenic animal models), renin inhibitors, angiotensin receptor antagonists, and bradykinin antagonists, will help to elucidate specific roles of the cardiac RAS in normal and failing hearts.

Nutritional value of soybean meal produced from conventional, high-protein, or low-oligosaccharide varieties of soybeans and fed to broiler chicks

Three experiments were conducted to determine the feeding value to broiler chicks of soybean meal (SBM) produced from high-protein (SBM-HP), low-oligosaccharide (SBM-LO), or conventional (SBM-CV) varieties of soybeans. The 3 SBM contained 54.9, 53.6, and 47.5% CP, respectively. The standardized digestibility (SDD) of amino acids (AA) in the 3 ingredients was measured using a precision-fed rooster assay with cecectomized Single Comb White Leghorn roosters. Results indicated that the SDD of AA was not different among the 3 sources of SBM, with the exception that the SDD of Lys in SBM-HP tended to be greater (P = 0.07) than that in SBM-CV. In the second experiment, a precision-fed rooster assay was used to measure the concentration of TME(n) in each source of SBM. Results indicated that the TME(n) in SBM-HP was greater (P < 0.001) than those in SBM-LO and SBM-CV (3,104 vs. 2,984 and 2,963 kcal/kg of DM). A 14-d growth performance experiment was also conducted using 120 Ross 308 male commercial broiler chicks (mean initial BW = 102.6 g) that were allotted to a completely randomized design. There were 5 chicks/pen and 8 replicate pens/diet. Three corn- and SBM-based diets were formulated based on the data for digestible AA and TME(n) that were measured in the previous experiments. Each source of SBM was used in 1 diet, but because of the greater concentrations of digestible AA in SBM-HP and SBM-LO than in SBM-CV, the inclusion of SBM-HP and SBM-LO were 31.21 and 32.60%, respectively, whereas an inclusion of 38.21% SBM-CV was used. There were no differences among the 3 diets for BW gain or feed efficiency, which indicated that the reduced inclusion rates of SBM-HP and SBM-LO compared with SBM-CV were not detrimental to broiler chick growth performance. It was concluded that, compared with SBM-CV, SBM-HP and SBM-LO are needed in lower concentrations in diets fed to broiler chicks because these 2 sources of SBM have a greater nutritional value than does SBM-CV.

Amino acid digestibility and concentration of digestible and metabolizable energy in soybean meal produced from conventional, high-protein, or low-oligosaccharide varieties of soybeans and fed to growing pigs

Two experiments were conducted to determine AA digestibility and the concentration of DE and ME in 5 sources of soybean meal (SBM). The 5 sources included hexane-extracted SBM produced from high-protein soybeans (SBM-HP) and conventional soybeans (SBM-CONV), and mechanically extruded-expelled SBM produced from high-protein soybeans (EE-SBM-HP), low-oligosaccharide soybeans (EE-SBM-LO), and conventional soybeans (EE-SBM-CONV). Five diets that each contained 1 source of SBM and a N-free diet were used in Exp. 1 to determine AA digestibility in each meal. Twelve growing barrows (initial BW: 67.7 +/- 1.34 kg) were allotted to a replicated 6 x 6 Latin square design with 6 periods and 6 diets in each square. Each period lasted 7 d, and ileal digesta were collected on d 6 and 7 of each period. Results of the experiment showed that the standardized ileal digestibility (SID) of all AA except Trp was similar for SBM-HP and SBM-CONV, but EE-SBM-HP and EE-SBM-LO had greater (P < 0.05) SID of His, Ile, Lys, Thr, and Val than EE-SBM-CONV. The SID of all indispensable AA in EE-SBM-HP was greater (P < 0.05) than in SBM-HP. The SID of Arg, Ile, Leu, and Phe in EE-SBM-CONV was greater (P < 0.05) than in SBM-CONV, but the SID of Trp was also greater (P < 0.05) in SBM-CONV than in EE-SBM-CONV. Experiment 2 was conducted to measure DE and ME in the same 5 sources of SBM as used in Exp. 1. Forty-eight growing barrows (initial BW: 38.6 +/- 3.46 kg) were placed in metabolism cages and randomly allotted to 6 diets with 8 replicates per diet. A corn-based diet and 5 diets based on a mixture of corn and each source of SBM were formulated. Urine and feces were collected during a 5-d collection period, and values for DE and ME in each source of SBM were calculated using the difference procedure. Results showed that the ME in SBM-HP tended to be greater (P = 0.10) than in SBM-CONV (4,074 vs. 3,672 kcal/kg of DM). The ME in EE-SBM-HP also tended to be greater (P = 0.10) than in EE-SBM-CONV and in EE-SBM-LO (4,069 vs. 3,620 and 3,721 kcal/kg of DM), but there was no difference in ME between extracted and extruded-expelled meals. It is concluded that SBM-HP has a greater feeding value than SBM-CONV because of greater concentrations of digestible AA and ME. Likewise, EE-SBM-LO has a greater concentration of most indispensable AA than EE-SBM-CONV, but the concentration of ME is similar in these 2 meals. Results of this experiment also showed that AA digestibility values in extruded-expelled SBM are greater than in hexane-extracted SBM.

Kinematic analysis of upper extremity joint motion in children using posterior walkers

This study applies an upper extremity model to analyze motion in 25 children with cerebral palsy using posterior walkers. The study indicates that throughout a gait cycle, the shoulders and wrist are in extension and the elbows are flexed. It also reveals that the elbows are the most asymmetrical joint of the upper extremities during walker-assisted ambulation.

Evidence for racial disparity in cardiac transplantation survival rates

Studies show that survival rates of cardiac transplantation are lower for African American transplant recipients than for Caucasians. Due to similarities in terms of etiology, treatment modalities and responses to these modalities, the authors examine some potential variables for survival of cardiac transplantation that have been well documented in both the renal transplantation literature and the medically managed congestive heart failure literature. The authors also discuss access to care, socioeconomic factors and immunological differences in attempting to identify relevant factors for survival of cardiac transplantation.

Effect of Host Plant Resistance and Reduced Rates and Frequencies of Fungicide Application to Control Potato Late Blight

Field experiments were conducted during 1998 to 2000 to determine the response of commercial potato cultivars and advanced breeding lines (ABL) differing in susceptibility to foliar late blight (caused by Phytophthora infestans) to reduced rates and frequencies of residual, contact fungicide applications. When environmental conditions were most favorable for the development of late blight, the lowest application rate of the fungicides chlorothalonil or fluazinam (33% of the manufacturers' recommended application rate [MRAR]) gave unsatisfactory control of potato late blight. Under conditions moderately conducive for late blight development, effective control was achieved with 33 to 66% MRAR with either fungicide. The Michigan State University advanced selection, MSG274-3, was the least susceptible ABL tested and, during 1998 to 2000, late blight was effectively managed using reduced rates of fungicides. Application rates of chlorothalonil (33 to 100% MRAR) significantly reduced late blight in the cultivar Snowden (5-day application interval) compared with the nontreated control; whereas, late blight was not effectively controlled in Snowden even at 100% MRAR of chlorothalonil at either 10- or 15-day application intervals in 1999 or 2000. The ABL MSG274-3 was the least susceptible of all cultivars and ABL used in this study, and required minimal chemical protection against late blight. The study demonstrates that ABL with reduced susceptibility to late blight can be managed with reduced fungicide rates and longer application intervals, thus offering more economical control of this disease.

Role of transglutaminase II in retinoic acid-induced activation of RhoA-associated kinase-2

Transamidation is a post-translational modification of proteins mediated by tissue transglutaminase II (TGase), a GTP-binding protein, participating in signal transduction pathways as a non-conventional G-protein. Retinoic acid (RA), which is known to have a role in cell differentiation, is a potent activator of TGASE: The activation of TGase results in increased transamidation of RhoA, which is inhibited by monodansylcadaverine (MDC; an inhibitor of transglutaminase activity) and TGaseM (a TGase mutant lacking transglutaminase activity). Transamidated RhoA functions as a constitutively active G-protein, showing increased binding to its downstream target, RhoA-associated kinase-2 (ROCK-2). Upon binding to RhoA, ROCK-2 becomes autophosphorylated and demonstrates stimulated kinase activity. The RA-stimulated interaction between RhoA and ROCK-2 is blocked by MDC and TGaseM, indicating a role for transglutaminase activity in the interaction. Biochemical effects of TGase activation, coupled with the formation of stress fibers and focal adhesion complexes, are proposed to have a significant role in cell differentiation.

The effect of muscle damage on strength and fatigue deficits

Many studies have reported prolonged force deficits after a bout of resistance training. However there is a dearth of information on the neuromuscular mechanisms underlying these deficits. This study examined whether an acute bout of resistance training had prolonged detrimental effects on muscle activation and excitation-contraction coupling. Two groups of 16 subjects each were tested before resistance exercise and at 1, 3, 5, and 7 days postexercise. A dvnamic group was tested for concentric and eccentric 1 repetition maximum and 3-methylhistidine (3-MH). An isometric group was tested for maximal voluntary contraction, muscle inactivation, relative fatigue, and evoked twitch properties. Both groups experienced similar increases in pain, limb circumference, and decreased range of motion between 1 and 3 days postexercise. Decrements occurred with eccentric strength, maximal voluntary contraction, muscle inactivation, relative fatigue, twitch amplitude, and increases in 3-MH. Although muscle damage-induced characteristics (pain, swelling, range of motion, 3-MH) were not correlated with neuromuscular impairments (muscle activation, force output), disruption of excitation-contraction coupling may have contributed to decrements in fatigue.

Regulation of angiotensinogen gene expression and protein in neonatal rat cardiac fibroblasts by glucocorticoid and beta-adrenergic stimulation

We previously demonstrated the presence of components for a renin-angiotensin system in fibroblasts cultured from neonatal rat ventricles, the regulation of expression of which has not been studied. Since glucocorticoids and beta-adrenergic stimuli have been implicated in cardiac hypertrophy, and function as regulators of the circulating renin-angiotensin system, we examined the effects of dexamethasone and isoproterenol on angiotensinogen mRNA levels and protein secretion in cultured neonatal rat cardiac fibroblasts. Treatment of cardiac fibroblasts for 8 h with 10 micromol/l isoproterenol or 100 nmol/l dexamethasone increased angiotensinogen mRNA levels by 246 +/- 7% and 1406 +/- 207%, respectively. Over 24 h, dexamethasone and isoproterenol increased angiotensinogen secretion by 148 +/- 32% and 123 +/- 26%, respectively. Angiotensin II, which has been reported to be a positive regulator of angiotensinogen synthesis and secretion in liver, markedly attenuated the effects of dexamethasone and isoproterenol on angiotensinogen mRNA expression and secretion. In the presence of 1 micromol/l angiotensin II, the stimulation in angiotensinogen secretion observed with dexamethasone and isoproterenol was decreased by 62% and 76%, respectively. The negative feedback of angiotensin II on angiotensinogen expression was primarily mediated through the type one angiotensin II (AT1) receptor (IC50 = 0.30 +/- 0.02 nmol/l). In summary, results from this study demonstrate that angiotensinogen mRNA levels and protein secretion in cardiac fibroblasts are positively regulated by glucocorticoid and beta-adrenergic stimulation. In addition, angiotensinogen production by cardiac fibroblasts is under negative feedback control of angiotensin II.

Cardiotrophin-1 increases angiotensinogen mRNA in rat cardiac myocytes through STAT3 : an autocrine loop for hypertrophy

-Cardiotrophin-1, an interleukin-6-related cytokine, stimulates the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway and induces cardiac myocyte hypertrophy. In this study, we demonstrate that cardiotrophin-1 induces cardiac myocyte hypertrophy in part by upregulation of a local renin-angiotensin system through the JAK/STAT pathway. We found that cardiotrophin-1 increased angiotensinogen mRNA expression in cardiac myocytes via STAT3 activation. Tyrosine phosphorylation of STAT3 by cardiotrophin-1 treatment resulted in STAT3 homodimer binding to the St-domain in the angiotensinogen gene promoter, which lead to promoter activation in a transient transfection assay. Cardiotrophin-1-induced STAT3 tyrosine phosphorylation and binding to the St-domain were suppressed by AG490, a specific JAK2 inhibitor, which also attenuated cardiotrophin-1-stimulated angiotensinogen promoter activity. Cardiotrophin-1 did not activate the angiotensinogen gene promoter that contained a substitution mutation within the St-domain. Finally, losartan, an angiotensin II type 1 receptor antagonist, significantly attenuated cardiotrophin-1-induced hypertrophy of neonatal rat cardiac myocytes. Angiotensin II is known to induce cardiac myocyte hypertrophy by activating the G-protein-coupled angiotensin II type 1 receptor. Our results suggest that upregulation of angiotensinogen and angiotensin II production contribute to cardiotrophin-1-induced cardiac myocyte hypertrophy and emphasize an important interaction between G-protein-coupled and cytokine receptors.

Angiotensin II-stimulated induction of sis-inducing factor is mediated by pertussis toxin-insensitive G(q) proteins in cardiac myocytes

The Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway is stimulated by angiotensin II (Ang II) via the type 1 receptor after acute pressure overload in the heart. The purpose of this study was to determine whether activation of the JAK-STAT pathway by Ang II is dependent on G proteins. Ang II (100 nmol/L for 120 minutes) caused formation of sis-inducing factor (SIF) complexes and tyrosine phosphorylation of STAT proteins in neonatal rat ventricular myocytes. The percentage of change in Ang II-stimulated SIF induction was not affected by pertussis toxin (PTX) or GP antagonist-2A, compounds that inhibit activation of G(i) and G(o) proteins. In contrast, GP antagonist-2A, a peptide that selectively inhibits activation of G(q) proteins, completely abolished Ang II-stimulated SIF induction and STAT3 tyrosine phosphorylation. Pretreatment of cardiac myocytes with U73122, an inhibitor of phosphatidylinositol-specific phospholipase C (PLC) activity, decreased Ang II-stimulated SIF induction and STAT3 tyrosine phosphorylation in a dose-dependent manner. Chelation of intracellular Ca(2+) with BAPTA-AM did not alter Ang II-stimulated SIF induction. In contrast, pretreatment of cardiac myocytes with Ro-31-8220, a potent and specific inhibitor of protein kinase C (PKC), decreased Ang II-stimulated SIF induction in a dose-dependent manner. Ang II-stimulated SIF induction was abolished in cardiac myocytes after downregulation of PKC by treatment with PMA. From these data, we conclude that Ang II-stimulated SIF induction and STAT3 tyrosine phosphorylation is mediated by PTX-insensitive G proteins through a G(q)-PLC-PKC-mediated pathway in neonatal rat ventricular myocytes.

The cardiac renin-angiotensin system: conceptual, or a regulator of cardiac function?

Angiotensin II, the effector peptide of the renin-angiotensin system, regulates cellular growth in response to developmental, physiological, and pathological processes. The identification of renin-angiotensin system components and angiotensin II receptors in cardiac tissue suggests the existence of an autocrine/paracrine system that has effects independent of angiotensin II derived from the circulatory system. To be functional, a local renin-angiotensin system should produce sufficient amounts of the autocrine and/or paracrine factor to elicit biological responses, contain the final effector (angiotensin II receptor), and respond to humoral, neural, and/or mechanical stimuli. In this review, we discuss evidence for a functional cardiac renin-angiotensin system.

Amplification of angiotensin II signaling in cardiac myocytes by adenovirus-mediated overexpression of the AT1 receptor

Low levels of AT1 receptor can make studying the growth-related signal transduction events mediated by this angiotensin II receptor in cardiac myocytes technically difficult. The purpose of the present study was to establish whether an adenovirus expression system could be used to increase the number of plasma membrane AT1 receptors in neonatal rat ventricular myocytes, thereby amplifying the signaling pathways activated by this receptor. Cardiac myocytes infected with adenovirus expressing the AT1 receptor exhibited increased ligand binding. The overexpressed receptor appeared to function like the endogenous receptor, in regard to agonist-induced internalization, as well as coupling to MAPK activation and protein tyrosine phosphorylation events. In addition, adenovirus-mediated overexpression of the AT1 receptor resulted in the amplification of angiotensin II intracellular signaling. In conclusion, adenovirus-mediated overexpression of angiotensin II receptors appears to be a useful strategy for studying the signal transduction events activated by this hormone in cardiac myocytes and for unraveling the molecular means by which this receptor type couples to a hypertrophic pattern of growth and gene expression.

Paracrine actions of cardiac fibroblasts on cardiomyocytes: implications for the cardiac renin-angiotensin system

Conditioned medium of cardiac fibroblasts was found to induce protein synthesis and signal transduction events rapidly, and to increase angiotensinogen messenger RNA (mRNA) levels in neonatal rat ventricular myocytes. Within 4 hours, fibroblast-conditioned medium (FCM) stimulated protein synthesis in cardiac myocytes, independent of the contractile state, and induced marked increases within 24 hours in total protein content. Endothelin- released by cardiac fibroblasts was not responsible for the stimulation of protein synthesis. FCM rapidly activated signal transduction events in cardiac myocytes associated with hypertrophic stimuli, including: (1) increased tyrosine phosphorylation of several prominent protein bands; (2) mitogen-activated protein kinases (ERK 1 and ERK 2); and (3) protein kinase C. Finally, FCM caused an increase at 8 hours in angiotensinogen mRNA levels of cardiac myocytes, whereas no effect was observed on mRNA levels for renin or the type 1 angiotensin II receptor (AT1). Our results suggest that cardiac fibroblasts produce a factor that rapidly activates cardiac myocyte growth through a membrane receptor that couples to conventional signal transduction pathways.

Highly corrected close-packed microlens arrays and moth-eye structuring on curved surfaces

The fabrication of near-micrometer-sized close-packed coherent microlens arrays on spheric or aspheric surfaces has been accomplished by use of a compact holographic projector system that was developed for producing multimicrometer down to submicrometer grid patterning on curved surfaces. The microlens arrays, which can be utilized as moth-eye relief structures, are formed in a photoimageable bisbenzocyclobutene polymeric resin by a photolytic process involving standing-wave interference patterns from the holographic projector system. Because of absorption, each integral microlenslet of the finished arrays possesses a near-paraboloid contour. The trajectories of the meridional rays from each microlenslet can be optimized to intersect at either a single point or a locus of points.

Highly corrected submicrometer grid patterning on curved surfaces

A compact holographic projector system was built and tested. This projection system offers a practical approach for making a highly corrected mesh or grid pattern on curved surfaces. The pattern can range in size from multimicrometer to submicrometer dimensions and be recorded in either positive or negative photoresist. Standing-wave interference patterns in the form of a diverging close-packed lattice of either hexagonal or square rodlike intensity maxima extending outward from a point or a locus of points are produced by multiple-beam holography that involves the combination of a holographic diffraction grating and a hypercomatic focusing objective.

Cross-talk between angiotensin II and interleukin-6-induced signaling through Stat3 transcription factor

In cultured neonatal rat cardiac fibroblasts and CHO-K1 cells expressing angiotensin II (Ang II) type 1 receptors (AT1) (T3CHO/AT1A cell line), Ang II induced a delayed tyrosine phosphorylation of Stat3 (Signal Transducers and Activators of Transcription) with maximal activation at 2 h. This was in contrast to the rapid tyrosine phosphorylation (15-30 min) of Stat3 by the cytokine interleukin-6 (IL-6). Using T3CHO/AT1A cells, we tested the hypothesis that the delayed tyrosine phosphorylation of Stat3 by Ang II resulted from the induction of an inhibitory pathway (0-30 min) prior to activation (1-2 h). In support of this hypothesis, we observed that a short treatment of cells with Ang II transiently inhibited the IL-6-induced Stat3 tyrosine phosphorylation. The inhibitory effect of Ang II could be attenuated by exposing the cells to a specific inhibitor of MAP kinase kinase 1, PD98059. Such modulatory cross-talk between Ang II and IL-6 may have relevance in pathophysiological conditions such as cardiac hypertrophy, and in acute phase and inflammatory responses.

Phosphorylation of the angiotensin II (AT1A) receptor carboxyl terminus: a role in receptor endocytosis

The molecular mechanism of angiotensin II type I receptor (AT1) endocytosis is obscure, although the identification of an important serine/threonine rich region (Thr332Lys333Met334Ser335Thr336Leu337 Ser338) within the carboxyl terminus of the AT1A receptor subtype suggests that phosphorylation may be involved. In this study, we examined the phosphorylation and internalization of full-length AT1A receptors and compared this to receptors with truncations and mutations of the carboxyl terminus. Epitope-tagged full-length AT1A receptors, when transiently transfected in Chinese hamster ovary (CHO)-K1 cells, displayed a basal level of phosphorylation that was significantly enhanced by angiotensin II (Ang II) stimulation. Phosphorylation of AT1A receptors was progressively reduced by serial truncation of the carboxyl terminus, and truncation to Lys325, which removed the last 34 amino acids, almost completely inhibited Ang II-stimulated 32P incorporation into the AT1A receptor. To investigate the correlation between receptor phosphorylation and endocytosis, an epitope-tagged mutant receptor was produced, in which the carboxyl-terminal residues, Thr332, Ser335, Thr336, and Ser338, previously identified as important for receptor internalization, were substituted with alanine. Compared with the wild-type receptor, this mutant displayed a clear reduction in Ang II-stimulated phosphorylation. Such a correlation was further strengthened by the novel observation that the Ang II peptide antagonist, Sar(1)Ile8-Ang II, which paradoxically causes internalization of wild-type AT1A receptors, also promoted their phosphorylation. In an attempt to directly relate phosphorylation of the carboxyl terminus to endocytosis, the internalization kinetics of wild-type AT1A receptors and receptors mutated within the Thr332-Ser338 region were compared. The four putative phosphorylation sites (Thr332, Ser335, Thr336, and Ser338) were substituted with either neutral [alanine (A)] or acidic amino acids [glutamic acid (E) and aspartic acid (D)], the former to prevent phosphorylation and the latter to reproduce the acidic charge created by phosphorylation. Wild-type AT1A receptors, expressed in Chinese hamster ovary cells, rapidly internalized after Ang II stimulation [t1/2 2.3 min; maximal level of internalization (Ymax) 78.2%], as did mutant receptors carrying single acidic substitutions (T332E, t1/2 2.7 min, Ymax 76.3%; S335D, t1/2 2.4 min, Ymax 76.7%; T336E, t1/2 2.5 min, Ymax 78.2%; S338D, t1/2 2.6 min, Ymax 78.4%). While acidic amino acid substitutions may simply be not as structurally disruptive as alanine mutations, we interpret the tolerance of a negative charge in this region as suggestive that phosphorylation may permit maximal internalization. Substitution of all four residues to alanine produced a receptor with markedly reduced internalization kinetics (T332A/S335A/T336A/S338A, t1/2 10.1 min, Ymax 47.9%), while endocytosis was significantly rescued in the corresponding quadruple acidic mutant (T332E/S335D/T336E/S338D, t1/2 6.4 min, Ymax 53.4%). Double mutation of S335 and T336 to alanine also diminished the rate and extent of endocytosis (S335A/T336A, 3.9 min, Ymax 69.3%), while the analogous double acidic mutant displayed wild type-like endocytotic parameters (S335D/T336E, t1/2 2.6 min, Ymax 77.5%). Based on the apparent rescue of internalization by acidic amino acid substitutions in a region that we have identified as a site of Ang II-induced phosphorylation, we conclude that maximal endocytosis of the AT1A receptor requires phosphorylation within this serine/threonine-rich segment of the carboxyl terminus.

Half-Fourier RARE MR cholangiopancreatography: experience in 300 subjects

PURPOSE

To determine prospectively the clinical applications and diagnostic accuracy of half-Fourier rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) cholangiopancreatography (MRCP) in a large patient population.

MATERIALS AND METHODS

Breath-hold, heavily T2-weighted half-Fourier RARE MRCP was performed in 265 patients with suspected pancreaticobiliary disease and in 35 control patients without symptoms or signs referrable to the biliary tract or pancreatic duct. MRCP findings were correlated with those at direct cholangiography, pathologic examination, cross-sectional imaging, and clinical follow-up.

RESULTS

Diagnostic MRCP examinations were obtained in 299 (99.7%) subjects. MRCP yielded an accuracy of 100% in determining the presence of pancreaticobiliary disease, the presence and level of biliary obstruction, and obstruction due to bile duct calculi. The accuracy of MRCP and MR imaging in determining the presence and level of malignant obstruction was 98.2%. MRCP obviated endoscopic retrograde cholangiopancreatography (ERCP) by excluding choledocholithiasis in patients with acute pancreatitis (n = 13) and nonspecific abdominal pain (n = 82). In patients with sclerosing cholangitis and acquired immunodeficiency syndrome cholangiopathy, MRCP depicted the biliary tract as clearly as did ERCP (n = 9). After failed ERCP, MRCP delineated the pancreaticobiliary tract and helped determine therapeutic options (n = 27).

CONCLUSION

Half-Fourier RARE MRCP enables accurate evaluation of pancreaticobiliary disease and obviates ERCP in some patients.

alpha-Thrombin inhibits signal transducers and activators of transcription 3 signaling by interleukin-6, leukemia inhibitory factor, and ciliary neurotrophic factor in CCL39 cells

We recently demonstrated that, in rat aortic smooth muscle cells, alpha-thrombin stimulated Stat3/SIF-A (signal transducers and activators of transcription 3/sis-inducing factor-A) activity [G. J. Bhat et al. (1997) Hypertension 29(Pt. 2), 356-360]. In the present study, we observed that exposure of CCL39 cells (a Chinese hamster lung fibroblast cell line) to alpha-thrombin resulted in a time-dependent decrease in basal SIF-A activity. We hypothesized that the decrease in basal SIF-A was due to the initiation of an inhibitory pathway, following alpha-thrombin exposure. To test this hypothesis, we determined if alpha-thrombin would inhibit Stat3 and SIF-A activation by interleukin-6 (IL-6), leukemia inhibitory factor (LIF), and ciliary neurotrophic factor (CNTF). In support of this hypothesis, alpha-thrombin inhibited the Stat3/SIF-A response induced by all the above cytokines. The inhibition by alpha-thrombin was concentration dependent, was sensitive to hirudin, and was mimicked by the thrombin receptor agonist peptide. The inhibition did not require the activation of phorbol 12-myristate 13-acetate-sensitive isoforms of protein kinase C and was reversed by pretreatment with the mitogen-activated protein kinase kinase 1 (MAPKK1 or MEK1) inhibitor PD98059. Inhibitory cross talk between alpha-thrombin and IL-6 was also observed in MRC-5 cells, a fibroblast cell line derived from human lung tissue. Thus, we identify a novel alpha-thrombin inhibitory pathway which, acting through a MAPKK1-dependent mechanism, blocks IL-6-, LIF-, and CNTF-induced Stat3/SIF-A activation. This inhibitory cross talk may provide an important regulatory function to modulate gene transcription by these cytokines, during immune and inflammatory responses.

Functional role for the angiotensin II receptor (AT1A) 3'-untranslated region in determining cellular responses to agonist: evidence for recognition by RNA binding proteins

We demonstrate a functional role for the 3'-untranslated region (3'-UTR) of the angiotensin II (Ang II) receptor subtype AT1A mRNA in Chinese hamster ovary (CHO-K1) cells by stably transfecting the coding region of the receptor gene with or without the 845 bp 3'-UTR. Two cell lines expressing similar levels of cell-surface receptors (with 3'-UTR, Bmax=571 fmol/mg protein; without 3'-UTR, Bmax=663 fmol/mg protein) were used in the present study. Both cell lines expressed high-affinity receptors (with 3'-UTR, Kd=0.83 nM; without 3'-UTR, Kd=0.82 nM), and binding studies with 125I-labelled Ang II in the presence of GTP[S] demonstrated that both coupled to heterotrimeric G-proteins. Despite these similarities, significant differences were observed for receptor-mediated cell signalling pathways. In cells without the 3'-UTR, Ang II stimulated an increase in cAMP accumulation (11-fold above control) and in cells with the 3'-UTR no stimulation was observed, which was consistent with previous observations in most endogenous Ang II receptor (AT1)-expressing cells. Activation of cAMP by Ang II in cells without the 3'-UTR correlated with an inhibition of DNA synthesis, determined by [3H]thymidine incorporation. Ang II-mediated responses were blocked by EXP3174, a selective non-peptide receptor antagonist. We also observed differences in the transient profiles of intracellular calcium between cells with and without the 3'-UTR in response to Ang II. In cells with the 3'-UTR, a sustained level of intracellular calcium was observed after Ang II stimulation, whereas cells without the 3'-UTR displayed a full return to basal level within 50 s of Ang II treatment. Even though the expressed exogenous gene is under the control of a constitutively expressing promoter (cytomegalovirus promoter), Northern-blot analysis revealed a considerably greater accumulation of AT1A mRNA in cells without the 3'-UTR compared with cells with the 3'-UTR. Analysis of the decay rate of the AT1A mRNA in cells with and without the 3'-UTR revealed that the normally unstable AT1A receptor mRNA became highly stable by removing its 3'-UTR, identifying a role for the 3'-UTR in mRNA destabilization. Interestingly, both cells express similar levels of receptors at the cell surface, suggesting that the 3'-UTR is also involved in the efficient translation and/or translocation of the receptor protein to the plasma membrane. We hypothesized that these 3'-UTR-mediated functions of the receptor are regulated by RNA-binding proteins. To identify possible RNA-binding proteins for the AT1A 3'-UTR, cellular extracts were prepared from parental CHO-K1 cells and 3'-UTR-binding assays, electrophoretic mobility-shift assays and UV crosslinking studies were performed. A major cellular protein of 55 kDa was identified, which specifically interacted with the 3'-UTR. Our data suggest that the 3'-UTR of the AT1A can control specific receptor functions, perhaps via selective recognition of the 3'-UTR by RNA-binding proteins.

Captopril modifies gene expression in hypertrophied and failing hearts of aged spontaneously hypertensive rats

The spontaneously hypertensive rat (SHR) exhibits a transition from stable compensated left ventricular (LV) hypertrophy to heart failure (HF) at a mean age of 21 months that is characterized by a decrease in alpha-myosin heavy chain (alpha-MHC) gene expression and increases in the expression of the atrial natriuretic factor (ANF), pro-alpha1(III) collagen, and transforming growth factor beta1 (TGF-beta1) genes. We tested the hypotheses that angiotensin-converting enzyme inhibition (ACEI) in SHR would prevent and reverse HF-associated changes in gene expression when administered prior to and after the onset of HF, respectively. We also investigated the effect of ACEI on circulating and cardiac components of the renin-angiotensin system. ACEI (captopril 2 g/L in the drinking water) was initiated at 12, 18, and 21 months of age in SHR without HF and in SHR with HF. Results were compared with those of age-matched normotensive Wistar-Kyoto (WKY) rats, and to untreated SHR with and without evidence of HF. ACEI initiated prior to failure prevented the changes in alpha-MHC, ANF, pro-alpha1(III) collagen, and TGF-beta1 gene expression that are associated with the transition to HF. ACEI initiated after the onset of HF lowered levels of TGF-beta1 mRNA by 50% (P<.05) and elevated levels of alpha-MHC mRNA two- to threefold (P<.05). Circulating levels of renin and angiotensin I were elevated four- to sixfold by ACEI, but surprisingly, plasma levels of angiotensin II were not reduced. ACEI increased LV renin mRNA levels in WKY and SHR by two- to threefold but did not influence LV levels of angiotensinogen mRNA. The results suggest that the anti-HF benefits of ACEI in SHR may be mediated, at least in part, by effects on the expression of specific genes, including those encoding alpha-MHC, ANF, TGF-beta1, pro-alpha1(III) collagen, and renin-angiotensin system components.

Molecular mechanisms of angiotensin II in modulating cardiac function: intracardiac effects and signal transduction pathways

Angiotensin II (Ang II), the effector peptide of the renin-angiotensin system (RAS), regulates volume and electrolyte homeostasis and is involved in cardiac and vascular cellular growth in humans and other species. This system, which has been conserved throughout evolution, plays an important role in cardiac and vascular pathology associated with hypertension, coronary heart disease, myocarditis and congestive heart failure. The traditional RAS is viewed as a system in which circulating Ang II is delivered to target organs and cells. However, in the past decade, a local RAS has been described in cardiac cells, providing evidence for autocrine and paracrine pathways by which biological actions of Ang II could be mediated. The critical actions of Ang II are mediated primarily through the AT1, G-protein (guanylyl nucleotide binding protein) coupled receptor. In addition to coupling to conventional G-protein signal transduction pathways, the AT1 receptor was recently shown to increase the tyrosine phosphorylation of several intracellular substrates, including the STAT (Signal Transducers and Activators of Transcription) family of novel transcription factors, in rat cardiac fibroblasts, myocytes and vascular smooth muscle cells, and AT1 receptor transfected CHO cells. It has been shown that Ang II stimulates the tyrosine phosphorylation and nuclear translocation of Stat1 (Stat 91) and Stat3 (Stat 92). Angiotensin II acting directly through the AT1 receptor, induces the formation of a complex of STAT proteins termed SIF (sis-inducing factor) which binds the DNA sequence, SIE (sis-inducing element) present in the promotor element of many genes. This provides evidence for a direct role of Ang II in mediating inflammatory and remodeling responses through the JAK-STAT pathway. Thus, it is likely that the JAK-STAT pathway has an important role in Ang II-mediated effects on gene transcription, cardiac and vascular cellular growth/development, and inflammatory responses.

Immunization registry: problems and prospects for boosting vaccine coverage of children

Case studies are presented on three organizational models for immunization registries in local communities: agency-based, facility-based, and population-based systems. The strengths and limitations of the respective approaches are highlighted. Each model faces three similar challenges: generating "real-time" information on the status of children who fall behind on their immunizations, assuring confidentiality of registrants and medical information, and maintaining operations amidst adverse social conditions that are at the root of underimmunization of children. With sufficient resources and cooperation among many private and public interests, registries have considerable potential to increase vaccination coverage among our population.

The type I angiotensin II receptor couples to Stat1 and Stat3 activation through Jak2 kinase in neonatal rat cardiac myocytes

The octapeptide, angiotensin II, has a modulatory role on cardiac cellular growth associated with hypertension and in compensatory remodeling following myocardial infarction. The molecular signal transduction pathways that participate in these and other cellular actions in response to angiotensin II are presently being elucidated. The signal transducers and activators of transcription (STAT) pathway directly links cytokine and growth factor receptors with transcriptional activity. We provide evidence that the G protein-linked, angiotensin II, AT1-receptor couples to activation of the STAT pathway in neonatal rat cardiac myocytes. Angiotensin II induces primarily sis-inducing factor (SIF) B and to a lesser extent SIF-C and SIF-A. The EC50 of this response was 40 nM and Stat1 and Stat3 proteins were identified as components of the SIF complexes. Stat1 and Stat3 were tyrosine phosphorylated five-fold and three-fold, respectively, over control levels following angiotensin II treatment of cardiac myocytes. Phosphorylation of Stat1 and Stat3 proteins was rapid (5 min) and sustained (60 min). Jak2 was also tyrosine phosphorylated eight-fold by angiotensin II treatment, and phosphorylated Stat1 and Stat3 proteins co-immunoprecipitated with activated Jak2 kinase. Selective inhibition of Jak2 kinase with AG-490 blocked formation of angiotensin II induced SIF complexes, suggesting that Jak2 kinase is required for cardiomyocyte SIF induction. In addition, Jak2, Stat1 and Stat3 proteins co-immunoprecipitated with the AT1-receptor. These are the first data to demonstrate coupling of a G-protein coupled receptor, AT1, to the JAK-STAT pathway in primary cultured cardiac myocytes and suggest that this pathway may be involved in transcriptional regulation by angiotensin II.

Long-term survival in typical thanatophoric dysplasia type 1

Thanatophoric dysplasia (TD), a severe skeletal dysplasia, is virtually always lethal neonatally, although a few previous reports have documented survival up to 4.75 years. We present a patient with survival beyond age 9 years and summarize his growth, development and medical history. The common Arg248Cys mutation in the extracellular region of fibroblast growth factor receptor 3 (FGFR3) was identified, eliminating the possibility that his long-term survival is attributable to an atypical mutation. This patient (and at least one other TD long-term survivor) have a rare skin disorder, acanthosis nigricans, which also occurs in Crouzon syndrome when caused by a FGFR3 mutation. Therefore, any molecular model of the origin of acanthosis nigricans secondary to FGFR3 mutations must account for the association of diverse mutations and these cutaneous effects.

Angiotensin II stimulates rapid serine phosphorylation of transcription factor Stat3

In rat neonatal cardiac fibroblasts and CHO-K1 cells expressing angiotensin type 1 receptors, angiotensin II (AII) rapidly caused a time dependent reduction in the SDS-polyacrylamide gel electrophoretic mobility of Stat3 (Signal Transducer and Activator of Transcription). This was concentration dependent and detected at a low/physiological concentration of AII (1 nM), with initial effect observed as early as 2 min; and maximal at 5 min. The rapid stimulation of Stat3 mobility retardation by AII, paralleled the rapid activation of MAP kinases (mitogen-activated protein kinases), and both were sensitive to the MAP kinase kinase 1 inhibitor, PD98059. Immunoprecipitation of Stat3 from [32P] labeled cells demonstrated a 4-fold increase in Stat3 phosphorylation in response to AII, and phosphoamino acid analysis indicated that phosphorylation occurred on serine residues. Angiotensin II-induced rapid phosphorylation of Stat3 was also sensitive to the MAP kinase kinase 1 inhibitor, PD98059. Treatment of immunoprecipitated Stat3 from AII-treated cells with protein phosphatase- PP-2A, reversed the AII-induced retardation of Stat3 mobility. These results demonstrate that AII rapidly induces Stat3 serine phosphorylation through a MAP kinase kinase 1 dependent pathway. Rapid stimulation of Stat3 serine phosphorylation by AII may have implications in the modulation of its transcriptional activity and gene expression.

Alcohol consumption among Oklahoma women: before and during pregnancy. The PRAMS Working Group. Pregnancy Risk Assessment Monitoring System

The Pregnancy Risk Assessment Monitoring System (PRAMS) utilizes a population-based survey of Oklahoma women with a recent live birth to examine the rates of alcohol consumption before and during pregnancy. Nearly one-half of Oklahoma women report using alcohol during the three months before pregnancy and one in thirteen women consume alcohol during the three months prior to delivery. Moderate to heavy alcohol use before pregnancy was associated with additional perinatal risk factors including unintended pregnancy, inadequate prenatal care, smoking, and physical abuse. Health providers play an important role in the prevention of alcohol related birth impairments such as fetal alcohol syndrome through early detection of problem drinking, patient education and appropriate referrals. However, one in four Oklahoma mothers report their health care provider did not talk to them about the harmful effects alcohol can have on their baby.

Alpha-thrombin stimulates sis-inducing factor-A DNA binding activity in rat aortic smooth muscle cells

Exposure of rat aortic vascular smooth muscle cells to alpha-thrombin resulted in the appearance of sis-inducing factor-A (SIF-A)-like DNA binding activity. This response to alpha-thrombin was delayed (detectable at 1 hour) compared with the rapid activation (15 to 30 minutes) by platelet-derived growth factor and the cytokine interleukin-6. alpha-Thrombin-induced SIF-A was sensitive to treatment with the tyrosine kinase inhibitor genistein. The thrombin inhibitor hirudin prevented the alpha-thrombin-mediated SIF-A induction. Cycloheximide had no effect on the ability of alpha-thrombin to induce SIF-A, suggesting that induction does not require new protein synthesis. alpha-Thrombin-induced SIF-A could be resolved into two additional subcomplexes termed SIF-A, and SIF-As. Antibodies against Stat3 reacted with alpha-thrombin-induced SIF-Af, suggesting that Stat3 or a related protein is present in this subcomplex. Induction of SIF-A DNA binding activity may contribute to alpha-thrombin-mediated cellular responses, including wound healing, cell proliferation, and inflammation in the vasculature.

Development and testing of a holographic projection system

We describe the development and testing of a holographic projection system that is used to produce micro-optical devices. The projector uses a two-dimensional two-phase-level diffraction grating to produce multiple coherent beams and an interferometric optical system behind the grating to recombine the beams to produce interference patterns that have been recorded within a photosensitive substrate. The two different substrates that we used are a diazo imaging material and a bisbenzocyclobutene (BCB) polymeric resin for fabrication of surface relief microstructures. After the exposed photosensitive substrate is developed, the recorded interference pattern forms a micro-optical device. The analysis and testing of these micro-optical devices show promise that this technique can form patterns uniformly over a region of several centimeters in diameter on flat or curved substrates. The experimental testing results of these micro-optical devices demonstrate that this method is a simple and energy efficient system to produce microstructures compared with other methods. These devices may be used as a new generation of directional light filters or monolithic microlenslet arrays that may have applications in communications, display, and components technologies.

Role of type 1 and type 2 angiotensin receptors in angiotensin II-induced cardiomyocyte hypertrophy

We compared the ability of angiotensin II (Ang II) to induce hypertrophy of neonatal rat ventricular myocytes with that of endothelin-1. Over 72 hours, Ang II (1 mumol/L) increased the ratio of protein to DNA by less than 10%, whereas endothelin-1 (100 nmol/L) produced a 28% increase. The growth effects of either agonist occurred independently of chronotropic actions. Radioligand binding studies showed that myocytes have nearly 300-fold more receptors for endothelin-1 than Ang II, and type 1 and type 2 Ang II receptor subtypes (AT1 and AT2) are present in near equal proportions. Cotreatment with a 10-fold molar excess of AT2 antagonists (PD 123177 or CGP 42112) for 72 hours augmented the Ang II-induced increase in the protein-to-DNA ratio to levels nearly as high (23%) as those with endothelin-1 (28%). AT2 antagonists enhanced Ang II stimulation of protein synthesis, as indexed by [3H]leucine incorporation, whereas an AT1 antagonist blocked Ang II-induced incorporation. An AT2 antagonist also prevented Ang II-induced protein degradation. In conclusion, Ang II-induced myocyte growth is tempered because of low AT1 levels and an antigrowth effect of AT2. These findings have potential clinical significance in that regression of hypertension-induced cardiac hypertrophy by AT1 antagonists may be in part due to an unopposed antigrowth effect of Ang II mediated via AT2.

Angiotensin II interferes with interleukin 6-induced Stat3 signaling by a pathway involving mitogen-activated protein kinase kinase 1

We reported recently that angiotensin II (AII) and phorbol 12-myristate 13-acetate (PMA) transiently inhibit interleukin 6 (IL-6)-stimulated tyrosine phosphorylation of signal transducers and activators of transcription 3 (Stat3) and subsequent formation of sis-inducing factor-A (SIF-A). However, the AII-mediated inhibition was independent of PMA-sensitive isoforms of protein kinase C (Bhat, G. J., Thekkumkara, T. J., Thomas, W. G., Conrad, K. M., and Baker, K. M. (1995) J. Biol. Chem. 270, 19059-19065). In this study, we demonstrate that the inhibition of IL-6-induced Stat3/SIF-A by AII is concentration-dependent and does not involve degradation of Stat3 protein. We hypothesized that the activation profile of the AII- and PMA-induced mitogen-activated protein (MAP) kinase cascade may be different from that of IL-6 and could contribute to the inhibitory effect; therefore, blocking the MAP kinase pathway at the level of MAPK kinase (MAPKK) would attenuate this inhibitory effect. AII and PMA rapidly induced high levels of MAP kinase activity (8-fold), which contrasted with the delayed and weak activation by IL-6 (1. 7-fold). Treatment of cells with PD98059, a specific inhibitor of MAPKK1, attenuated the inhibitory effects of AII and PMA on IL-6-induced Stat3 tyrosine phosphorylation and SIF-A formation. These data suggest that differences in magnitude and/or duration of activation of the MAP kinase cascade differentially affects the status of Stat3 tyrosine phosphorylation, and that MAPKK1 or a downstream intermediate is involved in the inhibition of IL-6-induced Stat3 by AII and PMA. Modulatory cross-talk between AII and IL-6 may have relevance in pathophysiological conditions such as cardiac hypertrophy and in acute phase and inflammatory responses.

Angiotensin II signalling pathways in cardiac fibroblasts: conventional versus novel mechanisms in mediating cardiac growth and function

Angiotensin II has been demonstrated to be involved in the regulation of cellular growth of several tissues in response to developmental, physiological, and pathophysiological processes. Angiotensin II has been implicated in the developmental growth of the left ventricle in the neonate and remodeling of the heart following chronic hypertension and myocardial infarction. The inhibition of DNA synthesis and collagen deposition in myocardial interstitium following myocardial infarction by angiotensin converting enzyme inhibitor, suggests that angiotensin II mediates interstitial and perivascular fibrobrosis by preventing fibroblast proliferation. In the past, little attention was focused on the identity and functional roles of cardiac fibroblasts. Recent in vitro studies utilizing cultured cardiac fibroblasts demonstrate that angiotensin II, acting via the AT1 receptor, initiates intracellular signalling pathways in common with those of peptide growth factors. Below, we describe growth-related aspects of cardiac fibroblasts with respect to angiotensin II receptors, conventional and novel signal transduction systems, secretion of extracellular matrix proteins and growth factors, and localization of renin-angiotensin system components.

Endothelin stimulates sis-inducing factor-like DNA binding activity in CHO-K1 cells expressing ETA receptors

ET-1, a member of the family of peptides known as endothelins, binds to a G-protein-coupled receptor, ET(A), and stimulates a variety of cellular responses, including contraction, growth, and mitogenesis. ET-1 stimulation of a chinese hamster ovary cell line stably transfected with the ET(A) receptor (CHO/ET(A)) induced formation of SIF (sis-inducing factor), a key component of the STAT (Signal Transducers and Activators of Transcription) pathway, in a concentration-dependent manner. SIF induction was blocked by a specific inhibitor of ET(A), BQ610, and by genistein, a tyrosine kinase inhibitor. This report demonstrates that ET-1 stimulates the STAT pathway of signal transduction through a G-protein-coupled receptor, ET(A), in this stably transfected cell line.

Evidence against a role for protein kinase C in the regulation of the angiotensin II (AT1A) receptor

Three putative protein kinase C phosphorylation sites in the carboxyl-terminal region of the angiotensin II AT1A receptor suggest that protein kinase C is involved in the regulation and desensitisation of this receptor. We investigated this possibility by measuring angiotensin II induced Ca2+ transients in cultures of neonatal rat cardiac fibroblasts which express predominantly the angiotensin AT1A receptor. Stimulating or inhibiting protein kinase C activity had no effect on angiotensin II stimulated Ca2+ transients. In addition, in situ and in vitro kinase assays revealed that a peptide, corresponding to the region of the angiotensin AT1A receptor containing the protein kinase C sites, was a poor substrate for protein kinase C. Thus, a heterologous desensitising role for this kinase on angiotensin AT1A receptors in these fibroblasts appears unlikely.

A role for cAMP in angiotensin II mediated inhibition of cell growth in AT1A receptor-transfected CHO-K1 cells

G-protein coupled Angiotensin II receptors (AT1A), mediate cellular responses through multiple signal transduction pathways. In AT1A receptor-transfected CHO-K1 cells (T3CHO/AT1A), angiotensin II (AII) stimulated a dose-dependent EC50 = 3.3 nM) increase in cAMP accumulation, which was inhibited by the selective AT1, nonpeptide receptor antagonist EXP3174. Activation of protein kinase C, or increasing intracellular Ca2+ with ATP, the calcium ionophore A23187 or ionomycin failed to stimulate cAMP accumulation. Thus, AII-induced cAMP accumulation was not secondary to activation of a protein kinase C- or ca2+/calmodulin-dependent pathway. Since cAMP has an established role in cellular growth responses, we investigated the effect of the AII-mediated increase in cAMP on cell number and [3H]thymidine incorporation in T3CHOA/AT1A cells. AII (1 microM) significantly inhibited cell number (51% at 96 h) and [3H]thymidine incorporation of 68% at 24 h) compared to vehicle controls. These effects were blocked by EXP3174, confirming that these responses were mediated through the AT1 receptor. Forskolin (10 microM) and the cAMP analog dibutyryl-cAMP (1 mM) also inhibited [3H]thymidine incorporation by 55 and 25% respectively. We extended our investigation on the effect of AII-stimulated increases in cAMP, to determine the role for established growth related signaling events, i.e., mitogen-activated protein kinase activity an tyrosine phosphorylation of cellular proteins. AII-stimulated mitogen-activated protein kinase activity and phosphorylation of the 42 and 44 kD forms. These events were unaffected by forskolin stimulated increases in cAMP, thus the AII-stimulated mitogen-activated protein kinase activity was independent of cAMP in these cells. AII also stimulated tyrosine phosphorylation of a number of cellular proteins in T3CHO/AT1A cells, in particular at 127 kD protein. The phosphorylation of the 127 kD protein was transient, reaching a maximum at 1 min, and returning to basal levels within 10 min. The dephosphorylation of this protein was blocked by a selective inhibitor of cAMP dependent protein kinase A, H89-dihydrochloride and preexposure to forskolin prevented the AII-induced transient tyrosine phosphorylation of the 127 kD protein. These data suggest that cAMP, and therefore protein kinase A can contribute to AII-mediated growth inhibition by stimulating the dephosphorylation of substrates that are tyrosine phosphorylated in response to AII.