Medical Disruptions During Center-Based Cardiac Rehabilitation: A Necessary Appraisal for the Development of Emerging Remote and Virtual Care Models

PURPOSE

The purpose of this study is to show that with remote and virtual cardiac rehabilitation (CR) care models rapidly emerging, CR core components must be maintained to prioritize safety and effectiveness. Currently, there is a paucity of data on medical disruptions in phase 2 center-based CR (cCR). This study aimed to characterize the frequency and types of unplanned medical disruptions.

METHODS

We reviewed 5038 consecutive sessions from 251 patients enrolled in cCR program from October 2018 to September 2021. Quantification of events was normalized to sessions to control for multiple disruptions that occurred to a single patient. A multivariate logistical regression model was used to predict comorbid risk factors for disruptions.

RESULTS

Fifty percent of patients experienced one or more disruptions during cCR. Glycemic events (71%) and blood pressure (12%) abnormalities accounted for most of these while symptomatic arrhythmias (8%) and chest pain (7%) were less frequent. Sixty-six percent of events occurred within the first 12 wk. The regression model showed that a diagnosis of diabetes mellitus was the strongest predictor for disruptions (OR = 2.66: 95% CI, 1.57-4.52; P < .0001).

CONCLUSIONS

Medical disruptions were frequent during cCR, with glycemic events being most common and occurring early. A diagnosis of diabetes mellitus was a strong independent risk factor for events. This appraisal suggests that patients living with diabetes mellitus, particularly those on insulin, need to be the highest priority for monitoring and planning and suggests that a hybrid care model may be beneficial in this population.

Limited effects of m6A modification on mRNA partitioning into stress granules

The presence of the m⁶A modification in mammalian mRNAs is proposed to promote mRNA recruitment to stress granules through the interaction with YTHDF proteins. We test this possibility by examining the accumulation of mRNAs in stress granules in both WT and ∆METTL3 mES cells, which are deficient in m⁶A modification. A critical observation is that all m⁶A modified mRNAs partition similarly into stress granules in both wild-type and m⁶A-deficient cells by single-molecule FISH. Moreover, multiple linear regression analysis indicates m⁶A modification explains only 6% of the variance in stress granule localization when controlled for length. Finally, the artificial tethering of 25 YTHDF proteins on reporter mRNAs leads to only a modest increase in mRNA partitioning to stress granules. Since most mammalian mRNAs have 4 or fewer m⁶A sites, and those sites are not fully modified, this argues m⁶A modifications are unlikely to play a significant role in recruiting mRNAs to stress granules. Taken together, these observations argue that m⁶A modifications play a minimal, if any, role in mRNA partitioning into stress granules.

Recent studies proposed that m⁶A modification in mammalian mRNAs increases their recruitment to stress granule. However, here the authors observed that m⁶A modification has a limited effect on mRNA entry into stress granules.

Abstract 218: Aerobic And Strength Training Improves Functional Capacity In Diabetic Patients Undergoing Cardiac Rehabilitation

Background: Traditional cardiac rehabilitation (CR) focuses on aerobic training to improve functional capacity and recovery after cardiovascular events. The use of combined aerobic and strength training is not yet standard of care despite its potential for improving functional capacity. The aim of this study was to characterize the effectiveness of a combined aerobic and strength training CR program for patients living with diabetes in comparison to patients without diabetes.

Methods: We retrospectively reviewed initial and final functional assessments for 167 patients participating in CR between 12/2019 - 9/2021. Functional capacity was assessed by the metabolic equivalent of task (METs) in a 6-minute walk test (6-MWT), arm curl reps, chair-to-stand reps, and timed up and go test. P-values were determined by the Mann Whitney U test and Wilcoxon signed rank test.

Results: Cohort characteristics and outcomes are listed in Table 1. Diabetic and non-diabetic patients improved in all measures of functional capacity, with arm curls and chair-to-stand exhibiting the greatest change. There was no statistical difference in outcomes between groups.

Conclusions: Diabetic patients had equivalent improvements in both aerobic and strength measures as their non-diabetic counterparts. This is an early dataset that highlights the effectiveness of combined aerobic and strength training to improve the quality of CR care for diabetic patients.

The misogyny of iron deficiency

Anaemia is common, particularly in women and the commonest underlying cause, iron deficiency, is often overlooked. Anaemia is associated with increased morbidity and mortality in patients undergoing anaesthesia; however, women are defined as being anaemic at a lower haemoglobin level than men. In this narrative review, we present the history of iron deficiency anaemia and how women's health has often been overlooked. Iron deficiency was first described as 'chlorosis' and a cause of 'hysteria' in women and initial treatment was by iron filings in cold wine. We present data of population screening demonstrating how common iron deficiency is, affecting 12-18% of apparently 'fit and healthy' women, with the most common cause being heavy menstrual bleeding; both conditions being often unrecognised. We describe a range of symptoms reported by women, that vary from fatigue to brain fog, hair loss and eating ice. We also describe experiments exploring the physical impact of iron deficiency, showing that reduced exercise performance is related to iron deficiency independent of haemoglobin concentration, as well as the impact of iron supplementation in women improving oxygen consumption and fitness. Overall, we demonstrate the need to single out women and investigate iron deficiency rather than accept the dogma of normality and differential treatment; this is to say, the need to change the current standard of care for women undergoing anaesthesia.

The landscape of eukaryotic mRNPs

The proper regulation of mRNA processing, localization, translation, and degradation occurs on mRNPs. However, the global principles of mRNP organization are poorly understood. We utilize the limited, but existing, information available to present a speculative synthesis of mRNP organization with the following key points. First, mRNPs form a compacted structure due to the inherent folding of RNA. Second, the ribosome is the principal mechanism by which mRNA regions are partially decompacted. Third, mRNPs are 50%-80% protein by weight, consistent with proteins modulating mRNP organization, but also suggesting the majority of mRNA sequences are not directly interacting with RNA-binding proteins. Finally, the ratio of mRNA-binding proteins to mRNAs is higher in the nucleus to allow effective RNA processing and limit the potential for nuclear RNA based aggregation. This synthesis of mRNP understanding provides a model for mRNP biogenesis, structure, and regulation with multiple implications.

Modulation of RNA Condensation by the DEAD-Box Protein eIF4A

Stress granules are condensates of non-translating mRNAs and proteins involved in the stress response and neurodegenerative diseases. Stress granules form in part through intermolecular RNA-RNA interactions, and to better understand how RNA-based condensation occurs, we demonstrate that RNA is effectively recruited to the surfaces of RNA or RNP condensates in vitro. We demonstrate that, through ATP-dependent RNA binding, the DEAD-box protein eIF4A reduces RNA condensation in vitro and limits stress granule formation in cells. This defines a function for eIF4A to limit intermolecular RNA-RNA interactions in cells. These results establish an important role for eIF4A, and potentially other DEAD-box proteins, as ATP-dependent RNA chaperones that limit the condensation of RNA, analogous to the function of proteins like HSP70 in combatting protein aggregates.

Multicolour single-molecule tracking of mRNA interactions with RNP granules

Ribonucleoprotein (RNP) granules are non-membrane-bound organelles that have critical roles in the stress response1,2, maternal messenger RNA storage3, synaptic plasticity4, tumour progression5,6 and neurodegeneration7-9. However, the dynamics of their mRNA components within and near the granule surface remain poorly characterized, particularly in the context and timing of mRNAs exiting translation. Herein, we used multicolour single-molecule tracking to quantify the precise timing and kinetics of single mRNAs as they exit translation and enter RNP granules during stress. We observed single mRNAs interacting with stress granules and P-bodies, with mRNAs moving bidirectionally between them. Although translating mRNAs only interact with RNP granules dynamically, non-translating mRNAs can form stable, and sometimes rigid, associations with RNP granules with stability increasing with both mRNA length and granule size. Live and fixed cell imaging demonstrated that mRNAs can extend beyond the protein surface of a stress granule, which may facilitate interactions between RNP granules. Thus, the recruitment of mRNPs to RNP granules involves dynamic, stable and extended interactions affected by translation status, mRNA length and granule size that collectively regulate RNP granule dynamics.

mRNP architecture in translating and stress conditions reveals an ordered pathway of mRNP compaction

Khong and Parker use single-molecule FISH to examine the timing of mRNA entry to stress granule as well as mRNA protein complex (mRNP) architecture. mRNA compaction increases after ribosome runoff, suggesting that mRNPs preferentially adopt a closed-loop structure in nontranslating conditions.

Stress granules (SGs) are transient membraneless organelles of nontranslating mRNA–protein complexes (mRNPs) that form during stress. In this study, we used multiple single-molecule FISH probes for particular mRNAs to examine their SG recruitment and spatial organization. Ribosome runoff is required for SG entry, as long open reading frame (ORF) mRNAs are delayed in SG accumulation, indicating that the SG transcriptome changes over time. Moreover, mRNAs are ∼20× compacted from an expected linear length when translating and compact ∼2-fold further in a stepwise manner beginning at the 5′ end during ribosome runoff. Surprisingly, the 5′ and 3′ ends of the examined mRNAs were separated when translating, but in nontranslating conditions the ends of long ORF mRNAs become close, suggesting that the closed-loop model of mRNPs preferentially forms on nontranslating mRNAs. Compaction of ribosome-free mRNAs is ATP independent, consistent with compaction occurring through RNA structure formation. These results suggest that translation inhibition triggers an mRNP reorganization that brings ends closer, which has implications for the regulation of mRNA stability and translation by 3′ UTR elements and the poly(A) tail.

Isolation of mammalian stress granule cores for RNA-Seq analysis

Stress granules are dynamic, conserved non-translating RNA-protein assemblies that form during cellular stress and are related to pathological aggregates in many neurodegenerative diseases. Mammalian stress granules contain stable structures, referred to as "cores" that can be biochemically purified. Herein, we describe a step-by-step guide on how to isolate RNA from stress granule cores for RNA-Seq analysis. We also describe a methodology for validating the RNA-Seq results by single molecule FISH and how to quantify the single molecule FISH results. These protocols provide a starting point for describing the RNA content of stress granules and may assist in the discovery of the assembly mechanisms and functions of stress granules in a variety of biological contexts.

The Stress Granule Transcriptome Reveals Principles of mRNA Accumulation in Stress Granules

Stress granules are mRNA-protein assemblies formed from nontranslating mRNAs. Stress granules are important in the stress response and may contribute to some degenerative diseases. Here, we describe the stress granule transcriptome of yeast and mammalian cells through RNA-sequencing (RNA-seq) analysis of purified stress granule cores and single-molecule fluorescence in situ hybridization (smFISH) validation. While essentially every mRNA, and some noncoding RNAs (ncRNAs), can be targeted to stress granules, the targeting efficiency varies from <1% to >95%. mRNA accumulation in stress granules correlates with longer coding and UTR regions and poor translatability. Quantifying the RNA-seq analysis by smFISH reveals that only 10% of bulk mRNA molecules accumulate in mammalian stress granules and that only 185 genes have more than 50% of their mRNA molecules in stress granules. These results suggest that stress granules may not represent a specific biological program of messenger ribonucleoprotein (mRNP) assembly, but instead form by condensation of nontranslating mRNPs in proportion to their length and lack of association with ribosomes.

Isolation of yeast and mammalian stress granule cores

Stress granules are dynamic, conserved RNA-protein (RNP) assemblies that form when translation is limiting; and are related to pathological aggregates in degenerative disease. Mammalian stress granules are comprised of two structures - an unstable shell and more stable cores. Herein we describe methodology for isolation of stress granule cores from both yeast and mammalian cells. The protocol consists of first enriching for stress granule cores using centrifugation and then further purifying stress granule cores using immunoprecipitation. The stress granule core isolation protocol provides a starting point for assisting future endeavors aimed at discovering conserved RNA regulatory mechanisms and potential links between RNP aggregation and degenerative disease.

The 5' untranslated region of a novel infectious molecular clone of the dicistrovirus cricket paralysis virus modulates infection

Dicistroviridae are a family of RNA viruses that possesses a single-stranded positive-sense RNA genome containing two distinct open reading frames (ORFs), each preceded by an internal ribosome entry site that drives translation of the viral structural and nonstructural proteins, respectively. The type species, Cricket paralysis virus (CrPV), has served as a model for studying host-virus interactions; however, investigations into the molecular mechanisms of CrPV and other dicistroviruses have been limited as an established infectious clone was elusive. Here, we report the construction of an infectious molecular clone of CrPV. Transfection of in vitro-transcribed RNA from the CrPV clone into Drosophila Schneider line 2 (S2) cells resulted in cytopathic effects, viral RNA accumulation, detection of negative-sense viral RNA, and expression of viral proteins. Transmission electron microscopy, viral titers, and immunofluorescence-coupled transwell assays demonstrated that infectious viral particles are released from transfected cells. In contrast, mutant clones containing stop codons in either ORF decreased virus infectivity. Injection of adult Drosophila flies with virus derived from CrPV clones but not UV-inactivated clones resulted in mortality. Molecular analysis of the CrPV clone revealed a 196-nucleotide duplication within its 5' untranslated region (UTR) that stimulated translation of reporter constructs. In cells infected with the CrPV clone, the duplication inhibited viral infectivity yet did not affect viral translation or RNA accumulation, suggesting an effect on viral packaging or entry. The generation of the CrPV infectious clone provides a powerful tool for investigating the viral life cycle and pathogenesis of dicistroviruses and may further understanding of fundamental host-virus interactions in insect cells.

IMPORTANCE

Dicistroviridae, which are RNA viruses that infect arthropods, have served as a model to gain insights into fundamental host-virus interactions in insect cells. Further insights into the viral molecular mechanisms are hampered due to a lack of an established infectious clone. We report the construction of the first infectious clone of the dicistrovirus, cricket paralysis virus (CrPV). We show that transfection of the CrPV clone RNA into Drosophila cells led to production of infectious particles that resemble natural CrPV virions and result in cytopathic effects and expression of CrPV proteins and RNA in infected cells. The CrPV clone should provide insights into the dicistrovirus life cycle and host-virus interactions in insect cells. Using this clone, we find that a 196-nucleotide duplication within the 5' untranslated region of the CrPV clone increased viral translation in reporter constructs but decreased virus infectivity, thus revealing a balance that interplays between viral translation and replication.

The small molecule genkwanine M induces single mode, mesenchymal tumor cell motility

Individual tumor cells utilize one of two modes of motility to invade the extracellular matrix, mesenchymal or amoeboid. We have determined that the diterpenoid genkwanine M (GENK) enhances the mesenchymal mode of cell motility that is intrinsic to HT-1080 osteosarcoma cells, stimulates a mesenchymal mode of motility in stationary MDA-MB-453 breast carcinoma cells, and induces a shift to a mesenchymal mode of cell motility in LS174T colorectal adenocarcinoma cells that normally utilize the alternate amoeboid mode of motility. The ability of GENK to stimulate or induce mesenchymal motility was preceded by a rapid cell spreading, elongation and polarization that did not require new gene expression. However, these initial morphologic changes were integrin dependent and they were associated with a reorganization of focal contacts and focal adhesions as well as an activation of the focal adhesion kinase. Therefore, GENK induces a mesenchymal mode of cell motility in a wide variety of tumor cell types that may be mediated, at least in part, by an activation of integrin-associated signaling.

A daphnane diterpenoid isolated from Wikstroemia polyantha induces an inflammatory response and modulates miRNA activity

MicroRNAs (miRNAs) are endogenously expressed single-stranded ∼21–23 nucleotide RNAs that inhibit gene expression post-transcriptionally by binding imperfectly to elements usually within the 3′untranslated region (3′UTR) of mRNAs. Small interfering RNAs (siRNAs) mediate site-specific cleavage by binding with perfect complementarity to RNA. Here, a cell-based miRNA reporter system was developed to screen for compounds from marine and plant extracts that inhibit miRNA or siRNA activity. The daphnane diterpenoid genkwanine M (GENK) isolated from the plant Wikstroemia polyantha induces an early inflammatory response and can moderately inhibit miR-122 activity in the liver Huh-7 cell line. GENK does not alter miR-122 levels nor does it directly inhibit siRNA activity in an in vitro cleavage assay. Finally, we demonstrate that GENK can inhibit HCV infection in Huh-7 cells. In summary, the development of the cell-based miRNA sensor system should prove useful in identifying compounds that affect miRNA/siRNA activity.

Modulation of stress granules and P bodies during dicistrovirus infection

Stress granules (SGs) are dynamic cytosolic aggregates composed of ribonucleoproteins that are induced during cellular stress when protein synthesis is inhibited. The function of SGs is poorly understood, but they are thought to be sites for reorganizing mRNA and protein. Several viruses can modulate SG formation, suggesting that SGs have an impact on virus infection. In this study, we have investigated the relationship of SG formation in Drosophila S2 cells infected by cricket paralysis virus (CrPV), a member of the Dicistroviridae family. Despite a rapid shutoff of host translation during CrPV infection, several hallmark SG markers such as the Drosophila TIA-1 and G3BP (RasGAP-SH3-binding protein) homologs, Rox8 and Rin, respectively, do not aggregate in CrPV-infected cells, even when challenged with potent SG inducers such as heat shock, oxidative stress, and pateamine A treatment. Furthermore, we demonstrate that a subset of P body markers become moderately dispersed at late times of infection. In contrast, as shown by fluorescent in situ hybridization, poly(A)(+) RNA granules still form at late times of infection. These poly(A)(+) RNA granules do not contain viral RNA nor do they colocalize with P body markers. Finally, our results demonstrate that the CrPV viral 3C protease is sequestered to SGs under cellular stress but not during virus infection. In summary, we propose that dicistrovirus infection leads to the selective inhibition of distinct SGs so that viral proteins are available for viral processing.

Phosphatidic acid is a pH biosensor that links membrane biogenesis to metabolism

Recognition of lipids by proteins is important for their targeting and activation in many signaling pathways, but the mechanisms that regulate such interactions are largely unknown. Here, we found that binding of proteins to the ubiquitous signaling lipid phosphatidic acid (PA) depended on intracellular pH and the protonation state of its phosphate headgroup. In yeast, a rapid decrease in intracellular pH in response to glucose starvation regulated binding of PA to a transcription factor, Opi1, that coordinately repressed phospholipid metabolic genes. This enabled coupling of membrane biogenesis to nutrient availability.

Effects of chemical manipulation of mitotic arrest and slippage on cancer cell survival and proliferation

Microtubule-targeting cancer therapies interfere with mitotic spindle dynamics and block cells in mitosis by activating the mitotic checkpoint. Cells arrested in mitosis may remain arrested for extended periods of time or undergo mitotic slippage and enter interphase without having separated their chromosomes. How extended mitotic arrest and mitotic slippage contribute to subsequent cell death or survival is incompletely understood. To address this question, automated fluorescence microscopy assays were designed and used to screen chemical libraries for modulators of mitotic slippage. Chlorpromazine and triflupromazine were identified as drugs that inhibit mitotic slippage and SU6656 and geraldol as chemicals that stimulate mitotic slippage. Using the drugs to extend mitotic arrest imposed by low concentrations of paclitaxel led to increased cell survival and proliferation after drug removal. Cells arrested at mitosis with paclitaxel or vinblastine and chemically induced to undergo mitotic slippage underwent several rounds of DNA replication without cell division and exhibited signs of senescence but eventually all died. By contrast, cells arrested at mitosis with the KSP/Eg5 inhibitor S-trityl-L-cysteine and induced to undergo mitotic slippage were able to successfully divide and continued to proliferate after drug removal. These results show that reinforcing mitotic arrest with drugs that inhibit mitotic slippage can lead to increased cell survival and proliferation, while inducing mitotic slippage in cells treated with microtubule-targeting drugs seems to lead to protracted cell death.

Using cyanide to put noble gases inside C60

After fullerenes are heated in the presence of a noble gas or an unreactive molecule at 650 degrees C and 3000 atm pressure, a small fraction of the fullerene molecules contain the atom or molecule. The incorporation fraction is greatly enhanced by adding potassium cyanide to the reaction mixture. The details of the preparation are described here.

Water vapor diffusion effects on gas dynamics in a sonoluminescing bubble

Calculations based on a consideration of gas diffusion of gas dynamics in a sonoluminescing bubble filled with a noble gas and water vapor are carried out. Xenon-, argon-, and helium-filled bubbles are studied. In the absence of shock waves, bubble temperatures are found to be decreased, a decrease attributable to the large heat capacity of water vapor. Peak bubble temperature reductions are seen in bubbles containing Xe or Ar but not in those containing He. Further extrapolations provide evidence for the occurrence of shock waves in bubbles with Xe and water vapor. No shock waves are observed in bubbles with Ar or He.

Synthesis, photochemistry and photophysics of stilbene-derivatized fullerenes

The photochemistry and photophysics of two sets of stilbene-derivatized fullerene isomers, in which stilbene is covalently linked to C60, are described. Synthesis and characterization of cis- and trans-stilbene substituted methanofullerenes 1 and 2, and cis- and trans-stilbene substituted fulleropyrrolidines 7 and 8 are described. While UV irradiation of the stilbene-substituted ketal precursors to 1 and 2 lacking the fullerene moiety afforded a photostationary state with 90:10 cis:trans ratio, similar to that of other model stilbene systems, direct and fluorenone-sensitized irradiation of 1 and 2 led to complete conversion to the trans isomer 2, as determined by HPLC analysis. The same results were obtained using cis-trans isomers 7 and 8, namely, the photostationary state on excitation below 350 nm is essentially 100% trans. No isomerisation in either system was obtained on excitation above 400 nm, where all the light is absorbed by the fullerene moiety. By analogy to previous studies of quenching of stilbene excited states, these results suggest that both singlet and triplet excited states of the trans-stilbene moiety in 2 and 8 are being quenched by intramolecular energy transfer to the attached C60, while the much shorter lived cis-stilbene excited states are not similarly quenched. Fluorescence studies on compound 8 support this hypothesis, since the characteristic fluorescence emission of trans-stilbene and trans-stilbene derivatives is not observed in the case of adduct 8. Because of the well established fact that trans-stilbene S1 states are longer lived than the S1 states of the corresponding cis isomers, rapid intramolecular singlet-singlet energy transfer to the appended C60 moiety, ket approximately 10(12) s(-1), is able to compete effectively with radiative and radiationless deactivation of the trans-stilbene S1 states in 2 and 8, but not in the corresponding cis isomers 1 and 7.

The effect of maternal prolactin infusion during pregnancy on fetal adipose tissue development

The present study determines whether maternal administration of prolactin (PRL) to dams promotes the abundance of the brown adipose tissue-specific uncoupling protein-1 (UCP1) in fetal and neonatal rat pups. Recombinant PRL (24 micro g/kg per day), or an equivalent volume of saline, were infused into dams (n=19 per group) throughout pregnancy from 12 h after mating. Interscapular brown adipose tissue was sampled either from fetuses at 19.5 days of gestation (term=21.5 days) or from neonatal rat pups at approximately 18 h after birth. The abundance of UCP1 was determined by immunoblotting on adipose tissue samples from individual pups and pooled from groups of pups. This analysis was complemented by immunocytochemistry on representative adipose tissue samples. Maternal PRL infusion resulted in a greater abundance of UCP1 in fetal rats at 19.5 days of gestation (control: 97.2+/-8.4% reference; PRL: 525.6+/-74.4% reference; P<0.001) and in neonates 18 h after birth. In contrast, the abundance of the outer mitochondrial membrane protein voltage-dependent anion channel was unaffected by PRL. Neonatal adipose tissue sampled from pups born to PRL-infused dams possessed fewer lipid droplets, but more UCP1, as determined by immunocytochemistry. Fetal, but not maternal, plasma leptin concentrations were also increased by maternal PRL administration. In conclusion, as rats are altricial, and the potential thermogenic activity of brown adipose tissue develops over the first few days of postnatal life, these changes prior to, and at the time of, birth implicate PRL in fetal and neonatal adipose tissue maturation.

Formation, isolation, spectroscopic properties, and calculated properties of some isomers of C(60)H(36)

Isomers of C(60)H(36) and He@C(60)H(36) have been synthesized by the Birch or dihydroanthracene reduction of C(60) and isolated by preparative high-pressure liquid chromatography. (3)He, (13)C, and (1)H NMR spectroscopic properties were then determined. A comparison of experimental chemical shifts against those computed using density functional theory (B3LYP) with polarized triple- and double-zeta basis sets for He and C,H, respectively, allowed provisional assignment of structure for several isomers to be made. Theoretical calculations have also been carried out to identify low-energy structures. The transfer hydrogenation method using dihydroanthracene gives a major C(60)H(36) isomer and a minor C(60)H(36) isomer with C(3) symmetry as determined by the (13)C NMR spectrum of C(60)H(36) and the (3)He NMR spectrum of the corresponding sample of (3)He@C(60)H(36). In view of the HPLC retention times and the (3)He chemical shifts observed for the Birch and dihydroanthracene reduction products, the two isomers generated by the latter procedure can be only minor isomers of the Birch reduction. A significant energy barrier apparently exists in the dihydroanthracene reduction of C(60) for the conversion of the C(3) and C(1) symmetry isomers of C(60)H(36) to the T symmetry isomer previously predicted by many calculations to be among the most stable C(60)H(36) isomers. Many of the (1)H NMR signals exhibited by C(60)H(36) (and C(60)H(18), previously reported) are unusually deshielded compared to "ordinary" organic compounds, presumably because the unusual structures of C(60)H(36) and C(60)H(18) result in chemical shift tensors with one or more unusual principal values. Calculations clearly show a relationship between exceptionally deshielded protons beta to a benzene ring in C(60)H(18) and C(60)H(36) and relatively long C-C bonds associated with these protons. The additional information obtained from 1D and 2D (1)H NMR spectra obtained at ultrahigh field strengths (up to 900 MHz) will serve as a critical test of chemical shifts to be obtained from future calculations on different C(60)H(36) isomers.

ATP transduces signals from ASGM1, a glycolipid that functions as a bacterial receptor

The flagella of the Gram-negative bacterium Pseudomonas aeruginosa serve not only for motility but also to bind bacteria to the host cell glycolipid asialoGM1 (ASGM1) through the protein flagellin. This interaction triggers defensive responses in host cells. How this response occurs is unclear because ASGM1 lacks transmembrane and cytoplasmic domains and there is little information about the downstream effectors that connect ASGM1 ligation to the initiation of host defense responses. Here, we show that ASGM1 ligation promotes ATP release from the host cell, followed by autocrine activation of a nucleotide receptor. This response links ASGM1 to cytoplasmic signaling molecules and results in activation of phospholipase C, Ca(2+) mobilization, phosphorylation of a mitogen-activated protein kinase (Erk 1/2), and activation of mucin transcription. These results indicate that bacterial interaction with host cells can trigger autocrine nucleotide signaling and suggest that agents affecting nucleotide receptors may modulate host responses to bacteria.

The clamshell incision for bilateral pulmonary artery reconstruction in tetralogy of Fallot with pulmonary atresia

BACKGROUND

Patients with tetralogy of Fallot/pulmonary atresia often have bilateral pulmonary artery lesions, including diminutive central and peripheral vessels, major aortopulmonary collaterals, and distortion from previous operations. Staged procedures through lateral thoracotomies and median sternotomies have traditionally been used for repair.

METHODS

Between October 1993 and December 1995, 10 patients 3 months to 15 years old with complex tetralogy of Fallot/pulmonary atresia underwent repair via a clamshell approach. Nine had undergone a mean of 2.8 +/- 0.8 previous operations (range 1 to 4). Indications for operation were repair of pulmonary artery arborization anomalies in 10 (4 unilateral, 6 bilateral), with unifocalization in 6 (2 unilateral, 4 bilateral).

RESULTS

Eight of 10 patients had concomitant complete repair. There were no deaths at a mean follow-up of 17.1 +/- 4.0 months (range 12 to 26). Mean ventilation time was 3.7 +/- 2.1 days (range 1 to 14) and hospital stay 8.7 +/- 4.6 days (range 4 to 19). At follow-up, the peak right ventricular/left ventricular pressure ratio in patients who received complete repair was 0.44 +/- 0.13 (0.30 to 0.67). One patient (10%) required reoperation because of pseudoaneurysm of the main pulmonary artery 14 months after repair, and one had successful stent placement because of recurrent left and right pulmonary artery stenosis 8 months after repair. Two infants who underwent complete unifocalization and central pulmonary artery reconstruction are awaiting completion of repair.

CONCLUSIONS

The clamshell approach to complex tetralogy of Fallot/ pulmonary atresia provides simultaneous exposure of bilateral central and peripheral pulmonary artery lesions and intracardiac pathologic conditions. This procedure appears safe and may decrease the number of operations required to complete repair of tetralogy of Fallot/pulmonary atresia in selected patients.