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The MIDCAB experience: a current look at evolving surgical and anesthetic approaches.

This article reviews and updates the recent modifications in patient selection and revisions in the anesthetic approach to MIDCAB surgery. It outlines the changing surgical selection criteria, current ways to assess graft patency, and evolving anesthetic management. A promising new advancement in coronary artery bypass, the minimally invasive technique has received varying reviews and undergoes careful evaluation. Increasing surgical experience, immediate postoperative assessment of graft patency, and improvement in surgical instruments are expected to improve patient outcome. A stratification of MIDCAB patients into status I and status II patients will aid in future evaluation of surgical and anesthetic outcome. Communication of newly developed techniques to those caring for cardiovascular patients is imperative.

Anesthesia↗

Evolving lineages of Symbiodinium-like dinoflagellates based on ITS1 rDNA.

Symbiodinium-like dinoflagellates have been shown to be a diverse group of endosymbionts that associate mutualistically with many kinds of coral reef dwellers, including cnidarians, molluscs, and protists. A high number of genetically ITS types of symbionts have been reported to date. However, whether these recently identified Symbiodinium ITS types indeed represent independent evolutionary lineages is still unsettled. Here I tested the null hypothesis that certain group of symbionts sampled from different geographical locations are derived from a single evolutionary lineage using a nested clade analysis (NCA). I analyzed a total of 174 ITS1 sequences from GenBank and pooled them into 74 ITS1 distinct haplotypes. Using these haplotypes, the statistical parsimony criterion produced 23 independent network trees, each one corresponding to a genetically independent evolving lineage. Some of these lineages revealed certain degree of specificity with some host groups at least at the phylum level. Within the previously described 28S-rDNA phylotype A, five ITS1 lineages were resolved. Phylotypes B and C resolved each in two ITS1 lineages. The highest ITS1 symbiont diversity was observed within the phylotype F, in which 11 lineages were resolved. Moreover, most of these lineages were associated uniquely with protist hosts from the group of foraminiferans. Here it is suggested that this high genetic diversity of endosymbionts associated with foraminiferans is linked with the evolution of soritacean foraminifera, which seems to have been driven by endosymbiosis. Lastly, the absence of genetic recombination presented in this study, suggest a lack of hybridisation at least among the major 28S-rDNA phylotypes within Symbiodinium-like dinoflagellates. This supports highly the idea that these phylotypes are indeed independent evolutionary units, which should be considered at least as different species. Whether they belong to the same genus or to different higher taxa still needs to be revised.

Animals↗

Evolving concepts of heart failure: cooling furnace, malfunctioning pump, enlarging muscle--Part I.

Understanding of the causes of dyspnea and anasarca, the cardinal features of heart failure, has changed dramatically since Greco-Roman times, when sputum and pleural effusions were thought to originate in the brain, and the heart was believed to heat and distribute the vital spirit. It was not until the seventeenth century, when Harvey demonstrated that the heart was a pump and autopsy descriptions revealed valve abnormalities that interfered with the circulation, that it became possible to identify the role of heart disease in causing shortness of breath and edema. Morgagni's recognition, toward the end of the eighteenth century, that overload caused the heart to enlarge was followed less than 50 years later by Corvisart's distinction between hypertrophy and dilation. Differences in the architecture of failing hearts focused attention of nineteenth-century clinical scientists on the myocardial response to overload, and by the end of this century overload-induced hypertrophy was recognized not only to have immediate adaptive effects, but also to cause progressive degeneration of the heart muscle. This focus on the failing myocardium ended in the early years of the twentieth century, when new discoveries in hemodynamic physiology shifted attention to pressure and flow abnormalities caused by the then prevalent rheumatic valvular heart disease. During the past decade, new emphasis on prognosis, along with realization that drugs intended to correct hemodynamic abnormalities often had adverse effects on survival, has led to a reexamination of the biology of the failing heart. As a result, the focus in heart failure research has returned to the myocardium. This article reviews some of the misconceptions and errors of early physicians, who, while often careful and intelligent observers, lacked the means to explain and treat heart failure. It is hoped an appreciation of the evolving concepts of heart failure will help the reader meet today's challenge of incorporating new information from molecular biology that holds the key to further progress in understanding the causes and therapy of this syndrome.

Cardiology↗

Time-evolving statistics of cavitation damage on metallic surfaces.

The statistics of surface damage on polycrystalline aluminium plates caused by acoustic cavitation is studied experimentally as a function of time. Cavitation is shown to produce a uniform distribution of crater-like holes with different depth, area and eccentricity. Most notably, the size distribution of such craters evolves with time from a gamma function into a power law. By contrast, on the surface of a martensitic Cu-Ni-Al crystal cavitation damage generates ramified patterns, reminiscent of a fractal object.

Acoustics↗

Viruses and the TNF-related cytokines, an evolving battle.

Tumor necrosis factor (TNF)-related cytokines are critical effector molecules in the immune response to viral pathogens. Engagement of the TNF receptors by their cognate ligands activates apoptotic and non-apoptotic signaling pathways, both of which can mediate antiviral activity. In response, viruses have evolved mechanisms to inhibit signaling by some cytokines of the TNF superfamily. These strategies are largely unique to each class of virus, but are similar in that they all target key regulatory checkpoints of the TNF pathway. In recent years, studies directed towards dissecting the mechanisms of TNF signaling and the viral retort have led to several significant discoveries, and form the basis for this review.

Animals↗

The evolving role of information technology in the drug discovery process.

Information technologies for chemical structure prediction, heterogeneous database access, pattern discovery, and systems and molecular modeling have evolved to become core components of the modern drug discovery process. As this evolution continues, the balance between in silico modeling and 'wet' chemistry will continue to shift and it might eventually be possible to step through the discovery pipeline without the aid of traditional laboratory techniques. Rapid advances in the industrialization of gene sequencing combined with databases of protein sequence and structure have created a target-rich but lead-poor environment. During the next decade, newer information technologies that facilitate the molecular modeling of drug-target interactions are likely to shift this balance towards molecular-based personalized medicine -- the ultimate goal of the drug discovery process.

Animals↗

High-grade maxillofacial osteosarcoma: evolving strategies for a curable cancer.

Maxillofacial osteosarcoma is a rare tumour. Curative treatment strategies have evolved to include chemotherapy in addition to definitive surgical resection. To review and report our experience in eight patients with maxillofacial osteosarcomas, we retrospectively reviewed eight patients with high-grade maxillofacial osteosarcoma seen over the last decade at our institution. Our results suggest that a combined surgical and chemotherapy approach provides excellent local disease control and high cure rates.

Adolescent↗

Population-based study of echocardiography. Time trends in utilization and diagnostic profile of an evolving technology, 1975-1987.

We evaluated trends in the use of echocardiography among residents of Olmsted County, Minnesota, from January 1, 1975, through June 30, 1987. Annual examinations per 100,000 population among Olmsted County residents increased 6-fold from 264 in 1975 to 1,644 in 1986. Given the pattern of echo use in Olmsted County, these population-based data project a potential annual utilization of 4 million echo exams in the United States. Marked increases over time in labeling of patients with regurgitant valvular heart disease were noted following the introduction of Doppler echocardiography. The diagnostic labeling associated with this evolving technology and the resultant apparent epidemic of valvular regurgitation present a significant clinical technology assessment dilemma.

Communication↗

Case study of the comparison of data from conference abstracts and full-text articles in health technology assessment of rapidly evolving technologies: does it make a difference?

OBJECTIVES: The aim of this study was to examine (i) the consistency of reporting research findings presented in conference abstracts and presentations and subsequent full publications, (ii) the ability to judge methodological quality of trials from conference abstracts and presentations, and (iii) the effect of inclusion or exclusion of data from these sources on the pooled effect estimates in a meta-analysis. METHODS: This report is a case study of a selected health technology assessment review (TAR) of a rapidly evolving technology that had identified and included a meta-analysis of trial data from conference abstracts and presentations. RESULTS: The overall quality of reporting in abstracts and presentations was poor, especially in abstracts. There was incomplete or inconsistent reporting of data in the abstract/presentations. Most often inconsistencies were between conference slide presentations and data reported in published full-text articles. Sensitivity analyses indicated that using data only from published papers would not have altered the direction of any of the results when compared with those using published and abstract data. However, the statistical significance of three of ten results would have changed. If conference abstracts and presentations were excluded from the early analysis, the direction of effect and statistical significance would have changed in one result. The overall conclusions of the original analysis would not have been altered. CONCLUSIONS: There are inconsistencies in data presented as conference abstracts/presentations and those reported in subsequent published reports. These inconsistencies could impact the final assessment results. Data discrepancies identified across sources included in TARs should be highlighted and their impact assessed and discussed. Sensitivity analyses should be carried out with and without abstract/presentation data included in the analysis. Incomplete reporting in conference abstracts and presentations limits the ability of reviewers to assess confidently the methodological quality of trials.

Congresses as Topic↗

Evolving management for critical pulmonary stenosis in neonates and young infants.

Over the years, management of critical pulmonary stenosis in young infants has evolved from surgical reconstruction of the right ventricular outflow tract and closed pulmonary valvotomy to transcatheter balloon valvoplasty. Our study aimed at evaluating how the changing policy for management had affected the immediate and long term outcomes of babies with this cardiac lesion. Interventions were made in 34 infants at a median age of 8.5 days (2-90 days). Reconstruction of the right ventricular outflow tract reconstruction was performed in 10 patients, closed pulmonary valvotomy in 13, and balloon valvoplasty in 11. Initial procedure-related mortality was 50%, 15% and 0% respectively. Multivariate analysis revealed transannular patching of the right ventricular outflow tract, and male sex, to be significant factors for death. For the 27 survivors, the ratio of right ventricular to systemic systolic pressure decreased from 1.6 +/- 0.3 to 0.3 +/- 0.2 after reconstruction of the outflow tract, 1.8 +/- 0.5 to 0.8 +/- 0.4 after closed valvotomy, and 1.8 +/- 0.6 to 0.9 +/- 0.3 after balloon valvoplasty. The decrease was significantly greater after patch reconstruction (p=0.025) that required no further reinterventions. The overall rate of reintervention for the survivors was 37% (10/27). The freedom from reintervention after closed valvotomy was 82%, 64% and 51% at 1, 5 and 10 years respectively. The figure remained at 78% at both 1 and 5 years (p=0.66) after balloon valvoplasty. The higher reintervention rate for closed valvotomy corresponded to the significantly greater residual gradient across the pulmonary valve noted on follow-up (p=0.01). Reinterventions included balloon dilation (n=6), reconstruction of the outflow tract (n=4), and 1 each of ligation of an arterial duct and systemic-pulmonary arterial shunting. The risk factor for reintervention was a hypoplastic right ventricle. In conclusion, transcatheter balloon valvoplasty appears to be the optimum initial approach in view of its low mortality, efficacy at relieving the obstruction, and low rate of reintervention.

Cardiac Surgical Procedures↗

Application of ion attachment mass spectrometry to evolved gas analysis for in situ monitoring of porous ceramic processing.

Ion attachment mass spectrometry was applied to evolved gas analysis-mass spectrometry (EGA-MS), generally known as thermogravimetry-mass spectrometry. Characteristic species arising from poly(vinyl alcohol) (PVA) and poly(methyl methacrylate) (PMMA) resin, used as a binder and a porogen, respectively, in the starting materials for porous ceramics, were detected in the mass spectra. The EGA curves of the characteristic mass peaks from PVA and PMMA, when plotted against the programmed temperature, successfully showed the individual pyrolysis behavior of each polymer during the firing process.

Journal Article↗

The manganese center of oxygen-evolving and Ca(2+)-depleted photosystem II: a pulsed EPR spectroscopy study.

The environment of the multi-manganese center in the O2-evolving complex (OEC) of plant photosystem II (PS II) under conditions of Ca2+ depletion has been probed using pulsed electron paramagnetic resonance (EPR) spectroscopy, and the following results are reported: (1) In Ca(2+)-depleted PS II membranes treated with the chelator [ethylenebis(oxyethylenenitrilo)]tetraacetic acid (EGTA), the modified Mn EPR signal arising from the OEC in the S2 state and the split EPR signal from the S3 state could be detected in the absorption mode by recording the amplitude of a two-pulse echo as a function of the external magnetic field. The formation of the S3 signal (g approximately 2.004; delta Hpp = 164 G) is not accompanied by the disappearance of the Mn EPR signal, although the signal becomes difficult to detect in CW EPR. This result supports the previous interpretation of the split S3 EPR signal as arising from the interaction of an organic radical with the Mn cluster [Boussac, A., Zimmermann, J. L., Rutherford, A. W., & Lavergne, J. (1990) Nature 347, 303-306]. (2) The two-pulse electron spin echo envelope modulation (ESEEM) spectra of the S2 state formed in Ca(2+)-depleted PS II membranes obtained from 14N- and 15N-labeled material are different. This indicates that nitrogen nuclei from nitrogen-containing protein residues are coupled to the Mn center in the S2 state of the inhibited enzyme. In addition, comparison with the two-pulse ESEEM data obtained for the S2 state in the untreated enzyme suggests that the coupling may be altered by the Ca2+ depletion and/or EGTA treatment. (3) The treatment of Ca(2+)-depleted PS II membranes with sodium pyrophosphate also induced a stable S2 state characterized by a modified multiline EPR signal that is similar to that obtained in EGTA-treated PS II membranes. Comparison of the ESEEM data obtained for the pyrophosphate and 14N and 15N samples treated with EGTA suggests that the modification induced by the EGTA treatment is accompanied by the binding of (an) EGTA molecule(s) to or near the Mn center. (4) ESEEM data obtained for the S3 state formed in the pyrophosphate or EGTA-treated enzyme are quite similar to those obtained for the corresponding S2 state. The data are also compared with ESEEM data obtained on oxidized 4(5)-methylimidazole obtained by UV irradiation. These results are discussed with respect to the current assignment of the S3 radical as arising from oxidation of a histidine residue.

Calcium↗

Investigation of the S3 electron paramagnetic resonance signal from the oxygen-evolving complex of photosystem 2: effect of inhibition of oxygen evolution by acetate.

An S3 electron paramagnetic resonance (EPR) signal is observed in a variety of photosystem 2 (PS2) samples in which the oxygen-evolving complex (OEC) has been inhibited. These signals have been proposed to be due to an interaction, S2X+, between the manganese cluster in an oxidation state equivalent to S2 and an organic radical, either oxidized histidine [Boussac et al. (1990) Nature 347, 303-306] or the tyrosine radical Yz+ [Hallahan et al. (1992) Biochemistry 31, 4562-4573]. We report that treatment of PS2 with acetate at pH 5.5 leads to a slowing of the reduction of Yz+ and allows the trapping of an S3-type state on freezing to 77 K following illumination at 277 K. The S3 EPR signal in acetate-treated PS2 has a broader and more complex line shape but otherwise has similar properties to other S3 signals. The addition to acetate-treated samples in the S1 state of the herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), which allows only a single turnover of the reaction center, causes a large reduction in the yield of the S3 signal. Various anion and cation treatments change the S3 signal line shape and are used to show that acetate probably acts by binding and displacing chloride. We propose that a variety of treatments which affect calcium and chloride cofactor binding cause a modification of the S2 state of the manganese cluster, slow the reduction of Yz+, and allow an S3 EPR signal to be observed following illumination.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗

Orientation of the Mn(II)-Mn(III) dimer which results from the reduction of the oxygen-evolving complex of photosystem II by NO: an electron paramagnetic resonance study.

The central part of the oxygen-evolving complex of photosystem II is a cluster of four manganese atoms. The known EPR spectra in the various oxidation states of the cluster are complicated by the magnetic interactions of the four Mn ions and accordingly are difficult to analyze. It has been shown recently that NO at -30 degrees C slowly reduces the cluster to a Mn(II)-Mn(III) state [Sarrou, J., Ioannidis, N., Deligiannakis, Y., and Petrouleas, V. (1998) Biochemistry 37, 3581-3587). We study herein the orientation dependence of the Mn(II)-Mn(III) EPR spectrum with respect to the thylakoid membrane plane. Both the powder and the oriented spectra are satisfactorily simulated with the same set of fine and hyperfine parameters assuming axial symmetry and collinear g and A tensors. The axial component of the tensors is found to be oriented at an angle of 20 degrees +/- 10 degrees to the membrane plane normal (mosaic spread Omega = 40 degrees ). We make the reasonable assumption that the Mn(II)-Mn(III) dimer is one of the di-mu-oxo units that has been suggested to comprise the Mn tetramer. On the basis of the sign of the hyperfine tensor anisotropy, the axial direction is assigned to the d(z(2)) orbital of Mn(III), which by comparison with synthetic model complexes is assumed to be oriented perpendicular to the Mn-(mu-oxo)-Mn plane. The present results complement earlier orientation studies by EXAFS and suggest that the Mn-(mu-oxo)-Mn plane makes a small angle (approximately 20 degrees) with the membrane plane and the axis connecting the bridging oxygens is approximately parallel to the plane.

Manganese↗

The manganese site of the photosynthetic oxygen-evolving complex probed by EPR spectroscopy of oriented photosystem II membranes: the g = 4 and g = 2 multiline signals.

The g = 4 and g = 2 multiline EPR signals arising from the Mn cluster of the photosynthetic oxygen-evolving complex (OEC) in the S2 state were studied in preparations of oriented photosystem II (PSII) membranes. The ammonia-modified forms of these two signals were also examined. The g = 4 signal obtained in oriented PSII membranes treated with NH4Cl at pH 7.5 displays at least 16 partially resolved Mn hyperfine transitions with a regular spacing of 36 G [Kim, D.H., Britt, R.D., Klein, M.P., & Sauer, K. (1990) J. Am. Chem. Soc. 112, 9389-9391]. The observation of this g = 4 "multiline signal" provides strong spectral evidence for a tetranuclear Mn origin for the g = 4 signal and is strongly suggestive of a model in which different spin state configurations of a single exchange-coupled Mn cluster give rise to the g = 4 and g = 2 multiline signals. A simulation shows the observed spectrum to be consistent with an S = 3/2 or S = 5/2 state of a tetranuclear Mn complex. The resolution of hyperfine structure on the NH3-modified g = 4 signal is strongly dependent on sample orientation, with no resolved hyperfine structure when the membrane normal is oriented perpendicular to the applied magnetic field. The dramatic NH3-induced changes in the g = 4 signal resolved in the spectra of oriented samples are suggestive that NH3 binding at the Cl- site of the OEC may represent direct coordination of NH3 to the Mn cluster.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Membrane↗

Oxygen-evolving photosystem II preparation from wild type and photosystem II mutants of Synechocystis sp. PCC 6803.

We present here a simple and rapid method which allows relatively large quantities of oxygen-evolving photosystem II- (PS-II-) enriched particles to be obtained from wild-type and mutants of the cyanobacterium Synechocystis 6803. This method is based on that of Burnap et al. [Burnap, R., Koike, H., Sotiropoulou, G., Sherman, L. A., & Inoue, Y. (1989) Photosynth. Res. 22, 123-130] but is modified so that the whole preparation, from cells to PS-II particles, is achieved in 10 h and involves only one purification step. The purified preparation exhibits a 5-6-fold increase of O2-evolution activity on a chlorophyll basis over the thylakoids. The ratio of PS-I to PS-II is about 0.14:1 in the preparation. The secondary quinone electron acceptor, QB, is present in this preparation as demonstrated by thermoluminescence studies. These PS-II particles are well-suited to spectroscopic studies as demonstrated by the range of EPR signals arising from components of PS-II that are easily detectable. Among the EPR signals presented are those from a formal S3-state, attributed to an oxidized amino acid interacting magnetically with the Mn complex in Ca(2+)-deficient PS-II particles, and from S2 modified by the replacement of Ca2+ by Sr2+. Neither of these signals has been previously reported in cyanobacteria. Their detection under these conditions indicates a similar lesion caused by Ca2+ depletion in both plants and cyanobacteria. The protocol has also been applied to mutants which have site-specific changes in PS-II. Data are presented on mutants having changes on the electron donor (Y160F) and electron acceptor (G215W) side of the D2 polypeptide.

Chlorophyll↗

Detection of structural changes upon S1-to-S2 transition in the oxygen-evolving manganese cluster in photosystem II by light-induced Fourier transform infrared difference spectroscopy.

The light-induced Fourier transform infrared (FT-IR) difference spectrum between the S1 and S2 states of the O2-evolving photosystem II (PSII) was obtained for the first time. Detection of an S2/S1 difference spectrum virtually free from contributions by the acceptor-side signals was achieved by employing an exogenous electron acceptor, potassium ferricyanide, to trypsin-treated PSII membranes and using one-flash excitation at 250 K. A synthetic difference spectrum obtained by adding this S2/S1 spectrum to the QA-/QA spectrum measured with Mn-depleted PSII was almost identical with the difference spectrum of the S2QA-/S1QA charge separation measured with untreated PSII. This successful simulation verifies the correctness of the S2/S1 spectrum thus obtained. The observed S2/S1 spectrum reflects the structural changes within the water-oxidizing Mn cluster upon the S1-to-S2 transition, most probably changes in vibrational modes of ligands coordinating to the Mn ion(s) that is (are) oxidized upon the S2 formation and/or changes in protein conformation. The present results demonstrate that FT-IR difference spectroscopy is a promising method to investigate the structure of the intermediates of the Mn cluster involved in photosynthetic water oxidation.

Cell Membrane↗