Bridging the Translational Gap in Heart Failure Research: Using Human iPSC-derived Cardiomyocytes to Accelerate Therapeutic Insights

Heart failure (HF) remains a leading cause of death worldwide, with increasing prevalence and burden. Despite extensive research, a cure for HF remains elusive. Traditionally, the study of HF's pathogenesis and therapies has relied heavily on animal experimentation. However, these models have limitations in recapitulating the full spectrum of human HF, resulting in challenges for clinical translation. To address this translational gap, research employing human cells, especially cardiomyocytes derived from human-induced pluripotent stem cells (hiPSC-CMs), offers a promising solution. These cells facilitate the study of human genetic and molecular mechanisms driving cardiomyocyte dysfunction and pave the way for research tailored to individual patients. Further, engineered heart tissues combine hiPSC-CMs, other cell types, and scaffold-based approaches to improve cardiomyocyte maturation. Their tridimensional architecture, complemented with mechanical, chemical, and electrical cues, offers a more physiologically relevant environment. This review explores the advantages and limitations of conventional and innovative methods used to study HF pathogenesis, with a primary focus on ischemic HF due to its relative ease of modeling and clinical relevance. We emphasize the importance of a collaborative approach that integrates insights obtained in animal and hiPSC-CMs-based models, along with rigorous clinical research, to dissect the mechanistic underpinnings of human HF. Such an approach could improve our understanding of this disease and lead to more effective treatments.

Abstract P1088: Polycystin-1 Protects Against Experimental Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia with a 1 in 4 lifetime risk. AF impairs cardiac function and increases the risk of stroke and heart attack. Although this is a common and harmful disease, little is known about the molecular mechanisms driving this disease. We have previously demonstrated that the protein polycystin-1 (PC1) plays a role in atrial cardiomyocyte excitation-contraction coupling in ventricular cardiomyocytes. Interestingly, patients with mutations in PC1 encoding gene have increased rates of atrial arrhythmias, including atrial fibrillation. Here, we sought to study the role of PC1 in atrial cardiomyocyte function and atrial fibrillation inducibility. We performed intracardiac electrophysiology with burst pacing in two mouse models with impaired PC1 function: 1) a mouse model harboring R3277C mutation (RC/RC) known to cause autosomal polycystic kidney disease, and 2) cardiomyocyte-specific PC1 KO (CKO). We observed increased rates of atrial fibrillation inducibility in both RC/RC and PC1 CKO mice compared to their respective control littermates (76.9% in RC/RC and 81.8% in CKO vs 20.0% and 11.1% in their respective WT controls). To elucidate molecular mechanisms driving increased susceptibility to atrial fibrillation, we determined whether PC1 affects excitation-contraction coupling in atrial cardiomyocytes. Human induced pluripotent stem cells-derived atrial cardiomyocytes (hiPSC-aCM) were treated with control or PC1 siRNA. Action potentials and intracellular calcium were measured using Fluovolt and Fluo-4, respectively. PC1 ablation decreased action potential duration and calcium transient peak amplitude elicited by electrical stimulation in hiPSC-CM. Decreased calcium transient peaks were also observed in HL-1 atrial cell line treated with siRNA and adult atrial cardiomyocytes isolated from RC/RC mice compared to their control counterparts. Unexpectedly, RNA-sequencing revealed altered DNA Damage Response gene expression. DNA damage has been implicated in the pathogenesis of atrial fibrillation. Therefore, we studied whether tachypacing elicited DNA damage in hiPSC-aCM. We observed increased levels of H2AX phosphorylation (gamma H2AX) in hiPSC-aCM with reduced PC1 expression. Our data show that PC1 mutations increase atrial fibrillation inducibility in multiple mouse models, likely due to impaired DNA damage response and altered action potential and calcium handling.

Abstract P1090: Polycystin-1 Regulates Calcium Handling And Contractility In Human IPSC-derived Ventricular Cardiomyocytes

Mutations in polycystin-1 (PC1) cause 85% of autosomal dominant polycystic kidney disease cases. This disease is characterized by progressive renal disease and multiple cardiovascular alterations. Evidence suggests that cardiovascular disease precedes the onset of renal failure. We recently demonstrated that PC1 ablation shortens cardiomyocyte action potential, decreases Ca 2+ transient amplitude, and reduces contractility in adult cardiomyocytes isolated from cardiomyocyte-specific PC1 knock-out mice compared to control mice. Alterations in Ca 2+ cycling in PC1-deficient cardiomyocytes were demonstrated to be due to action potential duration shortening and impaired sarcoendoplasmic reticulum ATPase activity. However, mouse and human cardiomyocytes have considerable differences in their action potential shapes and the ion channels involved. It remains unknown whether PC1 regulates these events in human cardiomyocytes. Here, we sought to investigate whether PC1 regulates excitation-contraction coupling in human ventricular cardiomyocytes. We differentiated commercially available human-induced pluripotent stem cell lines (hiPSC) into ventricular cardiomyocytes (hiPSC-CM) using published protocols (measurements were performed 60-90 days after differentiation). We developed a protocol to simultaneously measure action potentials (FluoVolt), intracellular Ca 2+ (Calbryte-590) and contractility using the IonOptix algorithm to detect changes in contrast as contractility measurements. PC1 ablation using siRNA decreased action potential duration and impaired Ca 2+ transients and contractility in hiPSC-CMs. Because hiPSC-CMs have several limitations due to their immature state, we employed a well-validated method to improve their maturation that utilizes a Matrigel mattress and hormone supplementation (dexamethasone; Dexa / thyroid hormone; T3; PMID: 28974554; developed by Dr. Bjorn Knollmann’s lab). Using the Matrigel mattress/Dexa/T3 technique, we increased hiPSC-CM maturation measured as follows: cardiomyocytes were oriented and contracted in the longitudinal axis, ryanodine receptor type 2 and alpha-actinin localized with a striated pattern, exhibited robust inward K + rectifier currents (I K1 ) and fired action potentials that resemble human adult cardiomyocytes. In this model, PC1 knockdown also decreased action potential duration and impaired Ca 2+ transients and decreased contractility measured as fractional shortening. Altogether, this evidence shows for the first time that PC1 regulates human cardiomyocyte physiology and suggests that cardiac alterations in patients with autosomal dominant polycystic kidney disease may emerge as a result of impaired cardiomyocyte contractile function.

Sound variation by hypertrophy and atrophy sonic muscle in the male southern black drum (Pogonias courbina)

The male and female southern black drum possess highly specialized, bilateral, striated sonic muscles used in sound production during courtship by males and in the production of disturbance calls by both males and females. Androgen-driven hypertrophy of the sonic muscles in males during the late spring spawning period results in increased growth of sonic muscle mass followed by post-spawning atrophy of sonic muscles. We examined changes in sonic muscle morphology and in the sound characteristics of males and females underlying seasonal changes in sonic muscle mass and muscle contraction as measured by sound production. In males, the sound pressure level increased while sound pulse duration decreased with increasing sonic muscle mass, indicating that sonic muscle fibers contract with greater force and shorter duration during the spawning season. Interpulse interval and the total number of pulses varied seasonally with muscle mass, which suggests that the effects of steroids on male southern black drum sound characteristics are more pronounced peripherally than in the central nervous system. In females, no increase in sonic muscle mass was found, and therefore, a change was not observed in the acoustic variables analyzed. Seasonal sonic muscle hypertrophy in males likely functions as a secondary sexual characteristic that maximizes vocalization amplitude or loudness during the spawning period.

Cefazolin-Induced Thrombocytopenia in a Patient with Polycythemia Vera Following Coronary Artery Bypass

Cefazolin is an antibiotic that is commonly administered perioperatively to reduce the risk of surgical site infections. Cephalosporins have a well-established safety profile, but have been associated with thrombocytopenia and neutropenia due to their myelosuppressive effects. While this effect may be benign in healthy patients undergoing minor surgery, it can be detrimental in patients with underlying hematologic disorders presenting for open-heart surgery. Herein, we discuss the first case in the literature of cefazolin-induced thrombocytopenia and severe coagulopathy in a patient with polycythemia vera (PCV) during a coronary artery bypass-grafting surgery.

Abstract P498: Polycystin-1 Regulates Excitation-contraction Coupling In Atrial Cardiomyocytes

Patients with Autosomal Dominant Polycystic Kidney disease (ADPKD) have multiple cardiovascular manifestations, including increased susceptibility to arrhythmias. Mutations in polycystin-1 (PC1) encoding gene accounts for 85% cases of ADPKD, whereas mutations in polycystin-2 (PC2) only accounts for 15%. In kidney cells, PC1 interacts with PC2 to form a protein complex at the primary cilia to regulate calcium influx via PC2. However, cardiomyocytes are non-ciliated cells and the role of both PC1 and PC2 in atrial cardiomyocytes remains unknown. We have previously demonstrated that PC1 regulates action potentials and calcium handling to fine-tune ventricular cardiomyocyte contraction. Here, we hypothesize that PC1 regulates action potentials and calcium handling in atrial cardiomyocytes independent of PC2 actions. To test this hypothesis, we differentiated human induced pluripotent stem cells (iPSC) into atrial cardiomyocytes (iPSC-aCM) using previously published protocols. To determine the contribution of PC1/PC2 in atrial excitation-contraction coupling, protein expression was knocked down utilizing specific siRNA constructs, for each protein, or a universal control siRNA transfected using lipofectamine RNAiMAX. We measured action potentials using the potentiometric dye FluoVolt and intracellular calcium with Fura-2 AM or Fluo-4. Changes in fluorescence were monitored using a multiwavelength IonOptix system. iPSC-aCM were paced at 2 Hz to synchronize the beating pattern using field electrical stimulation. Our data shows that PC1 ablation significantly decreased action potential duration at 50% and 80% of repolarization, by 24% and 23%, respectively. Moreover, we observed that PC1 knockdown significantly reduced calcium transient amplitude elicited by field electrical stimulation without changes in calcium transient decay. Interestingly, PC2 knockdown did not modify calcium transients in atrial cardiomyocytes (iPSC-aCM). Our data suggest that PC1 regulates atrial excitation-contraction coupling independent of PC2 actions. This study warrants further investigation into atrial dysfunction in ADPKD patients with PC1 mutations.

Abstract P464: Cardiac Dysfunction In A Mouse Model For Autosomal Dominant Polycystic Kidney Disease

Mutations in polycystin-1 (PC1) cause autosomal dominant polycystic kidney disease (ADPKD), a disorder that manifests with cardiac hypertrophy and dysfunction. We recently showed that cardiomyocyte-specific PC1 KO mice exhibit both systolic and diastolic dysfunction without signs of cardiac hypertrophy. The purpose of this study was to determine the effects of ADPKD-causing PC1 mutations on cardiac function using a mouse model for ADPKD harboring a mutation in PC1 R3277C (RC/RC). We used echocardiography to determine cardiac function and Western blot analysis to explore signaling pathways in WT and RC/RC mice (2-4 months of age).We observed a slight but significant decrease in ejection fraction (77.2±0.7 vs 86.2±2.4 %, N=5, 4, P=0.015) without signs of left ventricular hypertrophy (LV mass 78.4±5.5 vs 93.5±4.2 mg, N=5, 4, P>0.05) in RC/RC compared to WT mice. Western blot analysis from total heart lysates (WT and RC/RC; N=5) revealed no changes in protein levels of hypertrophic markers: beta myosin heavy chain (β-MHC) and regulator of calcineurin 1 (RCAN1). In addition, we studied multiple signaling pathways involved in cardiac hypertrophy by analyzing their phosphorylation status by Western blot (phosphorylated/total protein). We observed no changes in mTOR, S6K1 and S6 phosphorylation. However, a decrease in p-4EBP1 and p-eIF4B was observed in RC/RC compared to WT. Moreover, we observed a significant increase in p-ERK and p-CaMKII. Our data suggest that alterations in PC1 signaling promote cardiac dysfunction but do not promote hypertrophy in young mice (2-4 months of age). Published evidence (PMID: 32730856) suggest that RC/RC hearts become hypertrophic at 6 months of age. However, our data suggest there may be dysfunction prior to cardiac hypertrophy. This warrants further investigation into the more primary role of ADPKD-associated co-morbidities. More studies, with a larger animal cohort, are necessary to unveil the effects of mutant PC1 on cardiac function.

Polycystin-1 regulates cardiomyocyte mitophagy

Polycystin-1 (PC1) is a transmembrane protein found in different cell types, including cardiomyocytes. Alterations in PC1 expression have been linked to mitochondrial damage in renal tubule cells and in patients with autosomal dominant polycystic kidney disease. However, to date, the regulatory role of PC1 in cardiomyocyte mitochondria is not well understood. The analysis of mitochondrial morphology from cardiomyocytes of heterozygous PC1 mice (PDK1^+/- ) using transmission electron microscopy showed that cardiomyocyte mitochondria were smaller with increased mitochondria density and circularity. These parameters were consistent with mitochondrial fission. We knocked-down PC1 in cultured rat cardiomyocytes and human-induced pluripotent stem cells (iPSC)-derived cardiomyocytes to evaluate mitochondrial function and morphology. The results showed that downregulation of PC1 expression results in reduced protein levels of sub-units of the OXPHOS complexes and less functional mitochondria (reduction of mitochondrial membrane potential, mitochondrial respiration, and ATP production). This mitochondrial dysfunction activates the elimination of defective mitochondria by mitophagy, assessed by an increase of autophagosome adapter protein LC3B and the recruitment of the Parkin protein to the mitochondria. siRNA-mediated PC1 knockdown leads to a loss of the connectivity of the mitochondrial network and a greater number of mitochondria per cell, but of smaller sizes, which characterizes mitochondrial fission. PC1 silencing also deregulates the AKT-FoxO1 signaling pathway, which is involved in the regulation of mitochondrial metabolism, mitochondrial morphology, and processes that are part of cell quality control, such as mitophagy. Together, these data provide new insights about the controls that PC1 exerts on mitochondrial morphology and function in cultured cardiomyocytes dependent on the AKT-FoxO1 signaling pathway.

PKD2/polycystin-2 induces autophagy by forming a complex with BECN1

Macroautophagy/autophagy is an intracellular process involved in the breakdown of macromolecules and organelles. Recent studies have shown that PKD2/PC2/TRPP2 (polycystin 2, transient receptor potential cation channel), a nonselective cation channel permeable to Ca²⁺ that belongs to the family of transient receptor potential channels, is required for autophagy in multiple cell types by a mechanism that remains unclear. Here, we report that PKD2 forms a protein complex with BECN1 (beclin 1), a key protein required for the formation of autophagic vacuoles, by acting as a scaffold that interacts with several co-modulators via its coiled-coil domain (CCD). Our data identified a physical and functional interaction between PKD2 and BECN1, which depends on one out of two CCD domains (CC1), located in the carboxy-terminal tail of PKD2. In addition, depletion of intracellular Ca²⁺ with BAPTA-AM not only blunted starvation-induced autophagy but also disrupted the PKD2-BECN1 complex. Consistently, PKD2 overexpression triggered autophagy by increasing its interaction with BECN1, while overexpression of PKD2^D509V, a Ca²⁺ channel activity-deficient mutant, did not induce autophagy and manifested diminished interaction with BECN1. Our findings show that the PKD2-BECN1 complex is required for the induction of autophagy, and its formation depends on the presence of the CC1 domain of PKD2 and on intracellular Ca²⁺ mobilization by PKD2. These results provide new insights regarding the molecular mechanisms by which PKD2 controls autophagy.Abbreviations: ADPKD: autosomal dominant polycystic kidney disease; ATG: autophagy-related; ATG14/ATG14L: autophagy related 14; Baf A1: bafilomycin A₁; BCL2/Bcl-2: BCL2 apoptosis regulator; BCL2L1/BCL-XL: BCL2 like 1; BECN1: beclin 1; CCD: coiled-coil domain; EBSS: Earle's balanced salt solution; ER: endoplasmic reticulum; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; GOLGA2/GM130: golgin A2; GST: glutathione s-transferase; LAMP1: lysosomal associated membrane protein 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTORC1: mechanistic target of rapamycin kinase complex 1; NBR1: NBR1 autophagy cargo receptor; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PKD2/PC2: polycystin 2, transient receptor potential cation channel; RTN4/NOGO: reticulon 4; RUBCN/RUBICON: rubicon autophagy regulator; SQSTM1/p62: sequestosome 1; UVRAG: UV radiation resistance associated; WIPI2: WD repeat domain, phosphoinositide interacting 2.

Morphological analysis of aqueous humor drainage using QD nanoparticles and indocyanine green

This study represents the first morphological description of the lymphatic drainage of the ciliary body in vivo by comparative hyperspectral fluorescence imaging techniques of Quantum Qdot655 (QD) nanoparticles and indocyanine green (ICG). A volume of 1.25 μl of QD was injected into the left anterior camera of all rats. Similarly,1.25 μl of ICG diluted at a ratio of one-fourth with physiological saline solution was injected into the right anterior camera of all rats. The thickness of the skin in the mandibular area, connective tissue, and the depth of the mandibular lymph node (MLN) made image retrieval difficult. For QD, 302 nm UV excitation and 605 nm fluorescence peak emission were applied. The detection of QD and ICG used in this study in the MLNs is definitive evidence that aqueous humor (AH) follows a uveolymphatic pathway. Scanning electron microscope and the energy dispersive X-ray analyzer spectrum were used to examine both the Schlemm's canal and the MLN. For the first time, the QD was detected in the cortex of MLN. The QCM analysis of both QD-AH and ICG-AH was used to determine whether there was any interaction between them. This comparative study shows the importance of experimental animal modeling in pharmacological studies regarding eye research and drugs. In a female rat, the signal was taken from the parotid lymph node with QD injections.

Feasibility and safety of same day subcutaneous defibrillator implantation and send home (DASH) strategy

PURPOSE

To assess the feasibility and safety of same-day discharge after S-ICD implantation by implementing a specific analgesia protocol and phone follow-up.

METHODS

Consecutive patients presenting for outpatient S-ICD implantation were enrolled between 1/1/2018 and 4/30/2019. An analgesia protocol included pre-operative acetaminophen and oxycodone, intraoperative local bupivacaine, and limited use of oxycodone-acetaminophen at discharge. The primary outcome was successful same-day discharge. Numerical Pain Rating Scale (NPRS) on postoperative day (POD) 1, 3, 14, and 30 and any unplanned health care visits during the 1-month follow-up period were assessed.

RESULTS

Out of 53 potentially eligible S-ICD patients, 49 patients (92.5%) were enrolled and successfully discharged on the same day. Mean age of these 49 patients was 47 ± 14 years. There were no acute procedural complications. Severe pain (NPRS ≥ 8) on POD 0, 1, and 3 was present in 14.3%, 14.3%, and 8.2% of patients, respectively. The total in-hospital stay was 534 ± 80 min. Four unplanned visits (8%) due to cardiac or device-related issues occurred during 1-month follow-up, including 2 patients with heart failure exacerbation, one patient with an incisional infection, and one patient with inappropriate shocks.

CONCLUSIONS

With the appropriate institutional protocol including specific analgesics and phone follow-up, same-day discharge after outpatient S-ICD implantation is feasible and appears safe for most patients.. Device-related pain can be severe in the first 3 days post-implantation and can be successfully treated with limited supply of narcotic medications.

Tribute to Raymond Buriel (1948-2017): A Passionate Advocate for Chicana/o Studies and a Pioneer of Latinx Psychology

On June 21, 2017, the fields of Latinx Psychology, Chicana/o-Latina/o Studies, and education lost a trailblazing researcher, teacher, and mentor. Dr. Raymond Buriel made significant contributions to the study of acculturation and adjustment of Mexican immigrant families, with a special emphasis on the characteristics of immigrant students that are conducive to academic success. His seminal and widely cited publications on the psychological development of children who serve as language and cultural brokers for their families were among the first to illustrate the myriad of developmental assets of immigrant students. Buriel’s reputation as a mentor and advocate for countless undergraduate students, graduate students, and early career scholars was legendary. Affectionately referred to as “Papa Buri” by his Latinx undergraduate students, his legacy will continue to be felt in psychology and education. Many of his students now hold academic, research, policy, and administrative positions in major institutions and are leaders in their fields.

Cultural Involvement, Indigenous Identity, and Language

This exploratory study analyzed the influence of Zapotec parental socialization practices on the cultural awareness and involvement, ethnic identity, and Zapotec language use of their adolescent children. A total of 15 parent-child dyads participated in the study. Semi-structured interviews were conducted with parents. Adolescents responded to corresponding open-ended questions in a written survey. Results indicate that the children of parents who were the most involved in cultural groups and organizations were more likely to participate in traditional dance and music groups. The children of parents who identified as indigenous and encouraged Zapotec language use were more likely to also identify as indigenous and speak Zapotec. High cultural awareness and participation among adolescents was not always related to indigenous self-identification and/or Zapotec language use. Many adolescents who did not self-identify as indigenous and did not speak Zapotec also reported high levels of cultural awareness and involvement. Implications for parental socialization research on Mexican indigenous immigrants in the United States are discussed.

Acculturation, Social Identity, and Social Cognition: A New Perspective

The authors argue in this article that new approaches are needed in the study of psychological acculturation. They posit that a new model of psychological acculturation should incorporate contemporary work in social and cognitive psychology. The model they present builds on previous research in the areas of social cognition, cultural competence, social identity, and social stigma. Each of these perspectives is discussed in accordance with its relevance to the acculturative processes operating in immigrants. They hypothesize that acculturation is more difficult for those persons who must cope with the stigma of being different because of skin color, language, ethnicity, and so forth. Finally, the authors believe that the theoretical framework present here will lead to more productive insights into the adaptation process of immigrants than has heretofore been the case.

Cultural Orientation across Three Generations of Hispanic Adolescents

Acculturation among Hispanic adolescents involves learning the behaviors, beliefs, and values of American culture. This study examined changes in cultural orientation across three generations of adolescents (N = 203). Results indicated that Hispanic cultural orientation decreases in a linear trend across the first three generations, whereas American cultural orientation increases linearly. These findings suggest that within a few generations, most Hispanic adolescents exhibit a predominant American culture orientation while maintaining some traces of their Hispanic cultural orientation. Although home culture orientation diminishes across generations, it does not disappear completely. In addition, adolescents still retained allegiance to their Hispanic familial values.

The Relationship of Language Brokering to Academic Performance, Biculturalism, and Self-Efficacy among Latino Adolescents

Children who interpret for their immigrant parents are referred to as language brokers. The present study examines the relationship of language brokering to academic performance, biculturalism, academic self-efficacy, and social self-efficacy. The many adultlike experiences of children who broker on a regular basis suggest that their cognitive and socioemotional development may be accelerated relative to children of immigrant families who broker infrequently or not at all. Latino adolescents (n = 122) from immigrant families were participants in the study. Results showed that, as expected, language brokering was positively related to biculturalism, and in turn, both of these variables were positively related to academic performance. In addition, the strongest predictor of academic performance was academic self-efficacy. Results also indicated that, to some degree, language brokering is a gendered activity, with females reporting more brokering than males.

Echocardiographic assessment for ventricular assist device placement

While many factors depend on successful implantation and outcome of left ventricular assist devices (LVAD), echocardiography remains an integral part and is vital to the success of this process. Transesophageal echocardiography (TEE) allows interrogation of all the cardiac structures and great vessels. The pre-implantation TEE exam establishes a baseline and may identify potential problems that need palliation. Among these, most significant are aortic insufficiency (AI), intracardiac thrombi, poor right ventricular (RV) function, and intracardiac shunts. The post-implantation exam allows for adequate de-airing of the heart and successful LVAD initiation. The position and flow profiles of the inflow and outflow cannulas of the LVAD may be assessed. Finally, it assists in the astute management and vigilant identification and correction of a number of complications in the immediate post-implantation period. TEE will continue to remain vital to the successful outcomes LVAD patients.

Cerebral oxygenation and processed EEG response to clamping and shunting during carotid endarterectomy under general anesthesia

Clamping and shunting during carotid endarterectomy (CEA) surgery causes changes in cerebral blood flow. The purpose of this study was to assess and compare, side by side, the cerebral oxygenation (rSO2) and processed electroencephalogram (EEG) response bilaterally to carotid artery clamping and shunting in patients undergoing CEA under general anesthesia. With institutional approval and written informed consent, patients undergoing CEA under general anesthesia and routine carotid artery shunting were recorded bilaterally, simultaneously and continuously with an rSO2 and processed EEG monitor. The response of the monitors during carotid artery clamping and shunting were assessed and compared between monitors and bilaterally within each monitor. Sixty-nine patients were included in the study. At clamping the surgical-side and contralateral-side rSO2 dropped significantly below the baseline incision value (-17.6 and -9.4% respectively). After shunting, the contralateral-side rSO2 returned to baseline while the surgical-side rSO2 remained significantly below baseline (-9.0%) until the shunt was removed following surgery. At clamping the surgical-side and contralateral-side processed EEG also dropped below baseline (-19.9 and -20.6% respectively). However, following shunt activation, the processed EEG returned bilaterally to baseline. During the course of this research, we found the rSO2 monitor to be clinically more robust (4.4% failure rate) than the processed EEG monitor (20.0% failure rate). There was no correlation between the rSO2 or processed EEG changes that occurred immediately after clamping and the degree of surgical side stenosis measured pre-operatively. Both rSO2 and processed EEG respond to clamping and shunting during CEA. Cerebral oximetry discriminates between the surgical and contralateral side during surgery. The rSO2 monitor is more reliable in the real-world clinical setting. Future studies should focus on developing algorithms based on these monitors that can predict clamping-induced cerebral ischemia during CEA in order to decide whether carotid artery shunting is worth the associated risks. From the practical point of view, the rSO2 monitor may be the better monitor for this purpose.

Civic Engagement Patterns of Undocumented Mexican Students

This study examined the civic engagement of undocumented Mexican students. Civic engagement was defined as providing a social service, activism, tutoring, and functionary work. Survey data results ( n = 126) suggest that despite high feelings of rejection because of their undocumented status, part-time employment, and household responsibilities, 90% of respondents had been civically engaged. Females and students with higher academic achievement and extracurricular participation demonstrated higher civic engagement whereas older students were more likely to have participated in activism. Policy implications of undocumented Latino college student civic engagement are discussed.

Academic Resilience Among Undocumented Latino Students

This study examined the academic resilience of undocumented immigrant Latino students. It was hypothesized that due to their legal and social marginalization, students who experienced high risk accompanied by high levels of both personal and environmental protective factors would have higher academic outcomes than students with lower levels of these protective resources. The results from regression and cluster analyses ( N = 104) indicated that despite specific risk factors (e.g., elevated feelings of societal rejection, low parental education, and high employment hours during school) undocumented students who have high levels of personal and environmental protective factors (e.g., supportive parents, friends, and participation in school activities) report higher levels of academic success than students with similar risk factors and lower levels of personal and environmental resources. The results also suggested variability in risk exposure among undocumented students with some students reporting low levels of risk accompanied by high levels of personal and environmental protective factors.

Phase II trial of docetaxel and vinorelbine in patients with advanced non-small-cell lung cancer

PURPOSE

Docetaxel and vinorelbine are active agents in advanced non-small-cell lung cancer (NSCLC) and demonstrate preclinical synergism perhaps, in part, through their inactivation of the proto-oncogene bcl-2. We show that docetaxel (60 mg/m(2)) and vinorelbine (45 mg/m(2)) can be safely combined when given on an every 2-week schedule with filgrastim, with encouraging antitumor activity observed.

PATIENTS AND METHODS

Thirty-five chemotherapy naïve patients with advanced NSCLC received vinorelbine as an intravenous push immediately followed by docetaxel as a 1-hour intravenous infusion once every 2 weeks. Prophylactic corticosteroids, ciprofloxacin, and filgrastim were used.

RESULTS

We delivered median doses of 450 mg/m(2) of vinorelbine and 600 mg/m(2) of docetaxel. The major objective response rate was 51% (95% confidence interval [CI], 34% to 68%). With a median follow-up of 14 months, the predicted median survival time was 14 months, and the 1-year survival rate was 60% (95% CI, 44% to 80%). Febrile neutropenia occurred in five patients and five (1.3%) of 384 treatments. No dose-limiting neurotoxicity occurred. Symptomatic onycholysis and excessive lacrimation were observed after several months or more of therapy.

CONCLUSION

Docetaxel 60 mg/m(2) and vinorelbine 45 mg/m(2), both given every 2 weeks, is a highly active combination for the treatment of advanced NSCLC. Filgrastim largely obviates neutropenic fever and allows for the single-agent dose-intensity of both drugs to be delivered. The occurrence of certain late toxicities can limit use in some cases and suggests that the combination could also be beneficial in settings requiring briefer, fixed periods of treatment, such as in induction or postoperative therapy.

Phase I trial of docetaxel and vinorelbine in patients with advanced nonsmall cell lung carcinoma

BACKGROUND

With preclinical evidence of synergy, this dose-finding trial examining the combination of docetaxel and vinorelbine given with prophylactic filgrastim for the treatment of patients with nonsmall cell lung carcinoma was undertaken.

METHODS

Twenty-seven patients with advanced nonsmall cell lung carcinoma received vinorelbine as an intravenous push immediately followed by docetaxel as a 1-hour intravenous infusion once every 2 weeks at 1 of 7 different dose levels. Vinorelbine was escalated from 15 mg/m(2) (Level I) to 45 mg/m(2) (Level VII) and docetaxel was increased from 50 mg/m(2) (Level I) to 60 mg/m(2) (Level VII). Prophylactic corticosteroids and filgrastim were employed prospectively.

RESULTS

After completion of dose Level VII, accrual was terminated because Phase II dose intensity of both agents had been reached and further escalation was believed to be unsafe. At dose Level VII, one episode of first-cycle febrile neutropenia and a death after three treatment cycles due to Haemophilus influenzae sepsis (Grade 5 toxicity according to the Common Toxicity Criteria of the National Cancer Institute) without neutropenia were noted. In all, 209 treatment cycles were administered and febrile neutropenia was observed in only 4 of these treatments (1.9%). Bacteremia occurred in three patients (four episodes) in the absence of neutropenia. Symptomatic onycholysis was observed in three patients. Clinically significant peripheral neuropathy and fluid retention were rare. Confirmed partial responses were noted in 10 patients for a response rate of 37% (95% confidence interval, 20-57%).

CONCLUSIONS

Docetaxel at a dose of 60 mg/m(2) and vinorelbine at a dose of 45 mg/m(2), both given every 2 weeks, can be combined safely to achieve Phase II dose intensity of both agents. An ongoing Phase II trial will define the activity of this treatment combination.

Does rib cage-abdominal paradox signify respiratory muscle fatigue?

Studies suggesting that abnormal motion of the rib cage (RC) and abdomen (Ab) may indicate respiratory muscle fatigue have not separated the influence of respiratory load from that of fatigue in its pathogenesis. We hypothesized that abnormalities on RC-Ab motion are primarily related to increased load rather than fatigue. We tested this hypothesis in subjects breathing against resistive loads while maintaining 30 and 60% of maximum mouth pressure (Pmmax). RC-Ab asynchrony and paradox and the degree of variation in compartmental contribution to tidal volume were measured by inductive plethysmography and quantitated by the Konno-Mead method of analysis. Comparing measurements of base line and 30 and 60% of Pmmax indicated that the degree of asynchrony, paradox, and variation in compartmental contribution were significantly related to the level of the load; significant abnormalities were observed at even 30% of Pmmax, a target pressure that can be sustained indefinitely. In another group of subjects, fatigue was induced by sustaining 60% of Pmmax to the limits of tolerance. Indexes of abnormal RC-Ab motion increased from base line during the 1st min of loaded breathing but displayed no progression from the beginning to the end of the fatigue run. Immediately on discontinuation of the load, the indexes returned to levels similar to base line despite persistence of the fatigue state. These results in healthy subjects breathing against severe resistances indicate that RC-Ab asynchrony and paradox and variation in compartmental contribution to tidal volume are predominantly due to increases in respiratory load rather than muscle fatigue.

Konno-Mead analysis of ribcage-abdominal motion during successful and unsuccessful trials of weaning from mechanical ventilation

Respiratory muscle fatigue is considered a common cause of weaning failure but its detection is hampered by the lack of a satisfactory diagnostic test. Abdominal paradox has been proposed as a valuable clinical index of fatigue and thus its presence may lead to curtailment of weaning trials. However, sensitivity and specificity of this sign as a predictor of weaning outcome is unknown. We hypothesize that abnormal ribcage-abdominal (RC-Ab) motion is a common finding in the early stages of weaning and its presence does not inevitably imply an unsuccessful weaning outcome. We tested this hypothesis in patients undergoing a weaning trial: one group had a successful weaning outcome and were extubated (n = 10) and the other group failed the trial (n = 7). Normal RC-Ab motion was separately characterized in 17 healthy subjects. Employing a calibrated respiratory inductive plethysmograph, quantitative assessment of asynchrony and paradox was obtained by computing several indices from series of breaths at fixed time periods using the Konno-Mead method of analysis. During the weaning trial, both groups of patients displayed significant increases in asynchrony and Ab paradox compared to normal values. As a group, patients who failed the trial displayed significantly greater asynchrony and paradox of the RC and Ab than patients with a successful outcome. However, there was considerable overlap between the individual patients in the 2 study groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Accuracy of the respiratory inductive plethysmograph during loaded breathing

Indirect methods of measuring ventilation, such as the respiratory inductive plethysmograph (RIP), operate on the assumption that the respiratory system possesses two degrees of freedom of motion: the rib cage and abdomen. Accurate measurements have been obtained in many patients with pulmonary disease who possess additional degrees of freedom. Since calibration and validation of the RIP was carried out during quiet breathing in these patients, the amount of asynchronous or paradoxic breathing was presumably similar during the calibration and validation runs. Conversely, accuracy might be lost if following the initial calibration procedure the magnitude of chest wall distortion increased during subsequent validation runs. We calibrated the RIP during quiet breathing and examined its accuracy while subsequently breathing against resistive loads that required the generation of 20-80% of the subject's maximum inspiratory mouth pressure (Pmmax). We compared the relative accuracy of three commonly employed calibration methods: isovolume technique, least-squares technique, and single position loop-area technique. Up to 60% of Pmmax, 89% of the RIP values with the least-squares technique were within +/- 10% of simultaneous spirometric (SP) measurements and 100% were within +/- 20% of SP, compared with 63 and 91%, respectively, for the loop-area technique and 19 and 54%, respectively, for the isovolume technique. At 70 and 80% of Pmmax accuracy deteriorated. Accuracy of respiratory timing was judged in terms of fractional inspiratory time (TI/TT).(ABSTRACT TRUNCATED AT 250 WORDS)

The pattern of breathing during successful and unsuccessful trials of weaning from mechanical ventilation

We prospectively examined the pattern of breathing in patients being weaned from mechanical ventilation: one group (n = 10) underwent a successful weaning trial and were extubated, whereas another group (n = 7) developed respiratory failure and required the reinstitution of mechanical ventilation. During the period of ventilator support, minute ventilation (VI), tidal volume (VT), and respiratory frequency (f) were similar in the 2 groups. After discontinuation of the ventilator, VI remained similar in the 2 groups, but VT was lower and f was higher in the patients who failed the trial compared with those who were successful, 194 +/- 23 and 398 +/- 56 ml (p less than 0.001), respectively, and 32.3 +/- 2.3 and 20.9 +/- 2.8 breaths/min (p less than 0.001), respectively. The failure group displayed a significant increase in PaCO2 (p less than 0.005) during spontaneous breathing, without a concomitant increase in the alveolar-arterial PO2 difference. Eighty-one percent of the variance in PaCO2 was accounted for by the pattern of rapid, shallow breathing. During weaning, resting respiratory drive (reflected by mean inspiratory flow, VT/TI) and fractional inspiratory time (TI/Ttot) were similar in the 2 groups. The patients in the failure group showed significant increases in VT/TI, 265 +/- 27 to 328 +/- 32 ml/s (p less than 0.01), and VI, 5.82 +/- 0.53 to 7.32 +/- 0.52 L/min (p less than 0.01), from the beginning to the end of the weaning trial; VT and f showed no further change.(ABSTRACT TRUNCATED AT 250 WORDS)

Breathing pattern and metabolic behavior during anticipation of exercise

The mechanisms responsible for the marked increase in ventilation at the onset of exercise are incompletely defined. A conditioned response to exercise anticipation has been suggested as an influencing factor, but systematic measurements have not been made during the transition from rest to the time when exercise is anticipated but has not yet commenced. We tested the hypothesis that cortical activity associated with the anticipation of exercise causes hyperpnea, which is at least partly responsible for the increased ventilation at the onset of exercise. To assess the influence of continuous cortical activity in the absence of exercise anticipation the subjects performed mental arithmetic tasks. Fifteen subjects performed the two experiments in a random order. Ventilation was measured noninvasively using a calibrated respiratory inductive plethysmograph and end-tidal CO2 concentration (FETCO2) was monitored at the nasal vestibule. Both exercise anticipation and mental arithmetic caused an increase in minute ventilation (VI) (P less than 0.01) and mean inspiratory flow (VT/TI, P less than 0.01), which reflects respiratory center drive, although the derivation differed in that the former was volume based, whereas the latter was due to alteration in timing. Despite the increase in VI, FETCO2 remained constant in both instances. In a complementary study the constant FETCO2 in the face of increased VI was shown to be due to increased CO2 output. The results show that the mere anticipation of exercise causes an increase in ventilation. The mechanism responsible for this hyperpnea cannot be due solely to respiratory center activation because of the constancy of FETCO2 and the associated alterations in cardiac and metabolic behavior.

Separation of factors responsible for change in breathing pattern induced by instrumentation

Employment of mouthpiece and noseclips (MP + NC) has repeatedly been shown to increase tidal volume (VT), but its effect on respiratory frequency (f) and its subsets is controversial. The mechanisms accounting for this alteration in breathing pattern are poorly understood and may include stimulation of oral or nasal sensory receptors or alteration in the route of breathing. In this study we demonstrated that use of a MP + NC, compared with nonobtrusive measurement with a calibrated respiratory inductive plethysmograph, alters the majority of the volume and time indexes of breathing pattern, with increases in minute ventilation (P less than 0.01), VT (P less than 0.001), inspiratory time (TI, P less than 0.05), expiratory time (TE, P less than 0.05), mean inspiratory flow (P less than 0.05), and mean expiratory flow (P less than 0.05) and a decrease in f(P less than 0.05). Separating the potential mechanisms we found that when the respiratory route was not altered, independent oral stimulation (using an occluded MP) or nasal stimulation (by applying paper clips to the alae nasi) did not change the breathing pattern. In contrast, obligatory oral breathing without additional stimulation of the oral or nasal sensory receptors caused increases in VT (P less than 0.05), TI (P less than 0.05), and TE (P less than 0.01) and a fall in f(P less than 0.05). Heating and humidifying the inspired air did not prevent the alteration in breathing pattern with a MP. Thus change in the respiratory route is the major determinant of the alteration in breathing pattern with a MP + NC.(ABSTRACT TRUNCATED AT 250 WORDS)