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At least 379 records · Page 21Linked to original sources
PubMed2004

Spatially and temporally distinct expression of fibroblast connexins after sheep ventricular infarction.

OBJECTIVES: Myocardial infarction leads to extensive changes in the organization of cardiac myocytes and fibroblasts, and changes in gap junction protein expression. In the immediate period following ischemia, reperfusion causes hypercontraction, spreading the necrotic lesion. Further progressive infarction continues over several weeks. In reperfusion injury, the nonspecific gap junction channel uncoupler heptanol limits necrosis. We hypothesize that gap junction coupling and fibroblast invasion provide a substrate for progressive infarction via a gap junction mediated bystander effect. METHODS: A sheep coronary occlusion infarct model was used with samples collected at 12, 24 and 48 h, and 6, 12 and 30 d (days) post-infarction. Immunohistochemical labelling of gap junction connexins Cx40, Cx43, and Cx45 was combined with cell-specific markers for fibroblasts (anti-vimentin) and myocytes (anti-myomesin). Double and triple immunolabelling and confocal microscopy were used to follow changes in cardiac myocyte morphology, fibroblast content and gap junction expression after myocardial infarction. Gap junction protein levels and fibroblast numbers were quantified. RESULTS: Within 12 h of ischemia, myocyte viability is impaired within small islands in the ischemic region. These islands spread and fuse into larger infarct zones until 12 d post-infarction. Thereafter, surviving myocytes within the infarct and in the border-zone appear to become stabilized. Distant from the infarct, continuing myocyte disruption is regularly observed, even after 30 d. Cx43 becomes redistributed from intercalated discs to the lateral surface of structurally compromised myocytes within 12 d. Cx45 expressing fibroblasts infiltrate the damaged region within 24 h, becoming most numerous at 6-12 d post-infarction, with peak Cx45 levels at 6 d. Later, Cx43 expressing fibroblasts are observed, and the related Cx43 label increases over the 30 d observation period, even though fibroblast numbers decline after 12 d. Cx40 was only seen in vascular endothelium. CONCLUSIONS: Progressive infarction, identified by myocyte sarcomere disruption and subsequent cell loss, occurs in parallel with fibroblast invasion and gap junction remodeling. Two fibroblast phenotypes occur within infarcts, expressing either Cx43 or Cx45. Coupled fibroblasts may play a number of roles in tissue remodeling following myocardial infarction, including provision of a possible substrate for progressive infarction via a gap junction mediated bystander effect.

Animals↗
PubMed1986

The use of telemarketing in the community-wide prevention of heart disease: the Pawtucket Heart Health Program.

The marketing of preventive health behaviors is typically accomplished through various broadcast, print, and other mass media channels. By making randomly-dialed telephone calls to 4,000 residents of Pawtucket, RI, volunteers of the Pawtucket Heart Health Program succeeded in registering nearly 400 individuals for risk factor reduction groups or self-help behavior change kits. Additionally, community awareness of the program was an indirect benefit of this "telemarketing." Telemarketing is an interactive and inexpensive approach to marketing preventive health behaviors.

Heart Diseases↗
PubMed1975

Ultrastructural studies of regenerating spines of the sea urchin Strongylocentrotus purpuratus. I. Cell types without spherules.

The fine structure of regenerating tips of spines of the sea urchin Strongylocentrotus purpuratus was investigated. Each conical tip consisted of an inner dermis, which deposits and contains the calcite skeleton, and an external layer of epidermis. Although cell types termed spherulecytes containing large, intracellular membrane bound spherules were also present in spine tissues, only epidermal and dermal cell types lacking such spherules are described in this paper. The epidermis was composed largely of free cells representing several functional types. Over the apical portion of the tip these cells occurred in groups, while proximally they were distributed within longitudinal grooves present along the periphery of the spine from the base to the tip. The terminal portions of apical processes extending from some of the epidermal cells formed a thin, contiguous outer layer consisting of small individual islands of cytoplasm bearing microvilli. Adjacent islands were connected around the periphery by a junctional complex extending roughly 200 A in depth in which the opposing plasma membranes were separated by a narrow gap about 145 A in width bridged by amorphous material. Other epidermal cells were closely associated with the basal lamina, which was 900 A in thickness and delineated the dermoepidermal junction; some of these cells appeared to synthesize the lamina, while others may be sensory nerve cells. The dermis at the spine tip also consisted of several functional types of free cells; the most interesting of these was the calcoblast, which deposits the skeleton. Calcoblasts extended a thin, cytoplasmic skeletal sheath which surrounded the tips and adjacent proximal portions of each of the longitudinally oriented microspines comprising the regenerating skeleton, and distally, formed a conical extracellular channel ahead of the mineralizing tip. The intimate relationship between calcoblasts and the growing mineral surface strongly suggests that these cells directly control both the kinetics of mineral deposition and morphogenesis of the skeleton. Other cell types in the dermis were precalcoblasts and phagocytes. Precalcoblasts may function as fibroblasts and are possible precursors of calcoblasts. Closely associated with the basal lamina at the dermoepidermal junction were extracellular unbanded anchoring fi0rils 150 A to 200 A51 in diameter. Scattered proximally among dermal cells were other extracellular fibrils, presumably collagenous, about 300 A in diameter wit

Animals↗
PubMed2002

On the time-scales of magmatism at island-arc volcanoes.

Precise information on time-scales and rates of change is fundamental to an understanding of natural processes and the development of quantitative physical models in the Earth sciences. U-series isotope studies are revolutionizing this field by providing time information in the range 10(2)-10(4) years, which is similar to that of many modern Earth processes. I review how the application of U-series isotopes has been used to constrain the time-scales of magma formation, ascent and storage beneath island-arc volcanoes. Different elements are distilled-off the subducting plate at different times and in different places. Contributions from subducted sediments to island-arc lava sources appear to occur some 350 kyr to 4 Myr prior to eruption. Fluid release from the subducting oceanic crust into the mantle wedge may be a multi-stage process and occurs over a period ranging from a few hundred kyr to less than one kyr prior to eruption. This implies that dehydration commences prior to the initiation of partial melting within the mantle wedge, which is consistent with recent evidence that the onset of melting is controlled by an isotherm and thus the thermal structure within the wedge. U-Pa disequilibria appear to require a component of decompression melting, possibly due to the development of gravitational instabilities. The preservation of large (226)Ra disequilibria permits only a short period of time between fluid addition and eruption. This requires rapid melt segregation, magma ascent by channelled flow and minimal residence time within the lithosphere. The evolution from basalt to basaltic andesite probably occurs rapidly during ascent or in magma reservoirs inferred from some geophysical data to lie within the lithospheric mantle. The flux across the Moho is broadly andesitic, and some magmas subsequently stall in more shallow crustal-level magma chambers, where they evolve to more differentiated compositions on time-scales of a few thousand years or less.

Journal Article↗
PubMed2006

Fatigue and related human factors in the near crash of a large military aircraft.

INTRODUCTION: During approach to a remote island location, a U.S. Air Force heavy-airlift aircraft was flown into an aerodynamic stall, resulting in the loss of more than 4000 ft of altitude, with the crew recovering the aircraft just before impact would have occurred. METHODS: An analysis of the mishap was conducted through a review of non-privileged USAF mishap data, cockpit voice recordings, flight data records, and interviews of the aircrew involved. A thorough examination of fatigue-related factors was conducted, including computerized fatigue modeling. RESULTS: The crew traveled over 11,000 mi in a westward direction over a 6-d period. They had been on duty for nearly 21 h on the day of the mishap, with minimal in-flight rest. The pilots were late beginning their descent for landing, and a minor aircraft malfunction distracted the crew, contributing to channelized attention and degraded situational awareness. A breakdown in crew communication and failure to adequately monitor and interpret true aircraft state culminated in loss of aircraft control. Analysis of the crew's work/rest schedule confirmed that multiple elements of fatigue were present during this mishap, including acute and cumulative fatigue, circadian disruptions, and sleep inertia. Additionally, reduced situational awareness and spatial disorientation, exacerbated by the underlying fatigue, were causal in this mishap. DISCUSSION: This mishap highlights the importance of maintaining a high degree of situational awareness during long-haul flights with a continuing need to address issues regarding spatial disorientation, proper application of human engineering principles in modern cockpits, and mitigation of aircrew fatigue factors.

Accidents, Aviation↗
PubMed2006

Interaction with CagF is required for translocation of CagA into the host via the Helicobacter pylori type IV secretion system.

Development of severe gastric diseases is strongly associated with those strains of Helicobacter pylori that contain the cag pathogenicity island (PAI) inserted into the chromosome. The cag PAI encodes a type IV secretion system that translocates the major disease-associated virulence protein, CagA, into the host epithelial cell. CagA then affects host signaling pathways, leading to cell elongations and inflammation. Since the precise mechanism by which the CagA toxin is translocated by the type IV secretion system remained elusive, we used fusion proteins and immunoprecipitation studies to identify CagA-interacting secretion components. Here we demonstrate that CagA, in addition to other yet-unidentified proteins, interacts with CagF, presumably at the inner bacterial membrane. This interaction is required for CagA translocation, since an isogenic nonpolar cagF mutant was translocation deficient. Our results suggest that CagF may be a protein with unique chaperone-like function that is involved in the early steps of CagA recognition and delivery into the type IV secretion channel.

Antigens, Bacterial↗
PubMed2000

Deactivation, recovery from inactivation, and modulation of extra-synaptic ion currents in fish retinal ganglion cells.

As is shown magnificently by Heron Island's reef, the visual environment of many fishes includes various light intensities, hues and shapes that can change on large and small scales in space and time. Several articles in this issue address why fishes are sensitive to some of these properties, and how fishes and other aquatic species have acquired or fostered these sensitivities. This article discusses contributions of extrasynaptic ion currents, in a specific population of neurons, to the detection of ambient light levels, the appearance of certain visual stimuli and the disappearance of others.

Animals↗
PubMed1990

Geographical distribution of contaminants and productivity measures of herring gulls in the Great Lakes: Lake Erie and connecting channels 1978/79.

The distribution and size of colonies, residue levels of DDE, DDT, HCB, dieldrin, mirex and PCBs in eggs, productivity and eggshell thickness were determined for herring gulls at 14 sites in Lake Erie and connecting channels. The centre of distribution for breeding herring gulls was the Western Basin where approximately 90% of the 6200 nests in the study area were located. Seven of 22 colonies showed an average annual population increase of 48.3%. Most of the increase in breeding herring gulls on Lake Erie is directly associated with sites that have undergone habitat modification by man. Levels of PCBs and DDE ranged from 35 to 140 ppm (wet weight) and from 2.8 to 9.4 ppm, respectively; all other residues were less than 0.49 ppm. Most organochlorine residue levels were highest in eggs from colonies in or near the Niagara or Detroit Rivers. Mirex residues were greatest in the Niagara River and decreased significantly to the west. PCB residues were greatest in the Detroit River and decreased significantly to the east. The lowest levels generally came from colonies in the Sandusky Basin and near Pelee Island in western Lake Erie. Discriminant function analysis of six organochlorine contaminants correctly classified 90% or more of the eggs from up to four colonies in one or more years. Levels of PCBs and HCB appeared to have the greatest discriminating power. Herring gull productivity at all colonies (1-1.7 young gulls/pair) was normal and showed no significant geographical variation. Eggshell thickness was greatest in colonies in the Sandusky Basin and least in colonies in the Detroit River and extreme west end of the lake; mean eggshell thickness was 0.350 +/- 0.02 mm (6.7% thinning), which was weakly, but significantly correlated to DDE concentration. The variation in contaminants in herring gull eggs on a Basin basis (i.e., Western, Eastern, Sandusky, etc.) paralleled those known for sediments, water and fish. Thus, we suggest that in addition to its role as an indicator of lake-wide contamination of the Great Lakes, the herring gull, under some circumstances, may function as an indicator of "regional" contamination. This is an important distinction as it improves the geographical specificity of the herring gull as an indicator species on the Great Lakes, where it is a non-migratory species.

Animals↗
PubMed1986

Evidence for a secretory process, distinct from that of the aqueous humour, in the ciliary epithelium of Macaca mulatta.

In the ciliary epithelium of normal Rhesus monkeys, groups or islands of cells are present in which an intense secretory activity takes place. This is distinct from activity in aqueous humour production. In these regions of the epithelium the cytoplasm of the nonpigmented cells contains a well developed rough endoplasmic reticulum, numerous Golgi complexes and secretory granules containing an amorphous material of variable density. This material is discharged by a process of exocytosis into the intercellular spaces between the facing apices of the nonpigmented and pigmented cells and from here it percolates into the intercellular spaces between pigmented cells. The endothelial cells of the fenestrated capillaries located underneath these regions of actively secreting nonpigmented cells frequently contain, in their cytoplasm, granules of moderately dense material, suggesting a transport from the ciliary body stroma into the blood stream. Upon stimulation with pilocarpine the secretory activity of the nonpigmented cells is greatly increased and the intercellular spaces of the epithelium, including the ciliary channels, are frequently dilated and contain abundant osmiophilic material. These morphological observations suggest that, in addition to actively transporting aqueous humour, the ciliary epithelium produces a secretory material that diffuses into the ciliary body stroma and possibly enters into the blood stream across the walls of the fenestrated vessels.

Animals↗
PubMed1999

Differential distribution of inositol trisphosphate receptor isoforms in mouse oocytes.

In mammalian fertilization, inositol 1,4,5-trisphosphate receptor (IP3R)-dependent Ca2+ release is a crucial signaling event that originates from the vicinity of sperm-egg interaction and spreads as a wave throughout the egg cytoplasm. While it is known that Ca2+ is released by the type 1 IP3R in the egg cortex, the potential involvement of other isoform types responsible for the Ca2+ rise in the mouse egg (interior) and their spatial distribution are not known. In addition, the biochemical basis has not been definitively established for the development of increased sensitivity to inositol 1,4,5-trisphosphate (IP3) during meiotic maturation. Using specific antibodies to the type 1, 2, and 3 IP3R, we tested the hypotheses that different IP3R isoforms are responsible for the internal Ca2+ elevation and that they contribute to the maturation-associated acquisition of IP3 sensitivity. In both preovulatory oocytes and ovulated eggs of CF-1 mice, immunofluorescence revealed that types 1 and 2 isoforms were present in the cell cortex and interior. Type 1 was observed throughout the cytoplasm, and Western analysis indicated a 1.9-fold maturation-associated increase. In contrast, the signals detected for the type 2 (high-affinity) isoform and type 3 were present to a lesser extent, with type 2 restricted to isolated islands (similar to aggregates of vesicles detected by electron microscopy), which, in the cortex, may amplify early sperm-egg signaling events. The cortical-to-perinuclear localization of the receptor and cortical vesicle aggregates imply an efficient mechanism for propagating Ca2+ release from the cortex into the interior of the egg to activate development, and the isoform localization analysis indicates a clear spatial and biochemical heterogeneity. Types 1 and 2 isoforms were also present in granulosa cells.

Amino Acid Sequence↗
PubMed1996

[A morphological study of human epipharyngeal mucosa: 10 autopsy cases].

The epipharynx lies between the nasal cavity and the mesopharynx, which is behind the oral cavity. It is a conduit for respired air, contributes to the equalization of pressure within the middle ear space via the eustachian tube and is closed by the soft palate during swallowing of food and fluid. It acts as a drainage channel for the mucous secreted by the nose and the glands within the epipharynx area. Various exchanges of the epipharyngeal mucosa occur because of the function of the epipharynx. In this study, distribution of the 3 types of epithelium in the epipharynx, which are ciliated, transitional and squamous epithelium, was investigated. The specimens of the mucosa with the bony wall of the epipharynx were collected from 10 autopsy cadavers at, (6 males and 4 females, aged from 37 to 83 years). Distribution of the 3 types of epithelium differed with the type, but there was no marked difference between the right and left halves of the epipharynx. Therefore, the distribution pattern was investigated by drawing superimposed geographical schemata of the epithelia, which were confirmed histologically in all 10 cases. The results obtained were as follows. On the superior-posterior wall, the squamous epithelium was invaginated into an area of the ciliated epithelium just like islands or bands in the nasal side and the epithelia of all 3 types were mixed in the mesopharyngeal side. The lateral wall was covered with a mixture of ciliated and transitional epithelia on the nasal side from the posterior lip of the eustachian tube and with a mixture of transitional and squamous epithelia on its mesopharyngeal side. The inferior wall was covered mostly with ciliated epithelium on the nasal side and with squamous epithelium on the mesopharyngeal side from Passavant's ridge. The transitional epithelium was distributed like an island between the areas of the ciliated and squamous epithelia in the lateral wall. The clearly definite schema of the 3 types of epithelium in the epipharynx, reported by Ali, has been generally accepted. However, the 3 types appeared as a mosaic or an island in the epipharyngeal wall and their distribution pattern was different in each individual.

Adult↗
PubMed2005

Particulate carbon measurements in California's San Joaquin Valley.

Aerosol carbon sampling methods and biases were evaluated during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS) and Fresno Supersite programs. PM2.5 sampling was conducted using Desert Research Institute (DRI) sequential filter samplers (SFS) from December 1999 through February 2001 at two urban sites (Fresno and Bakersfield), one regional transport site (Angiola), and two boundary sites (Bethel Island and Sierra Nevada Foothills) during CRPAQS in the San Joaquin Valley (SJV). Additional filter-based sampling was done in Fresno as part of the US Environmental Protection Agency (EPA) Supersites program. Organic carbon (OC) and elemental carbon (EC) concentrations were higher during winter (December-February) than summer (June-August) and this trend was most pronounced at Fresno and Bakersfield. OC and EC displayed similar diurnal trends during winter and summer at Fresno and during winter at Angiola. The diurnal pattern at Angiola reflected the transport of secondary pollutants to the site. Collocated measurements of OC and EC on undenuded quartz-fiber filters were made at Fresno with the DRI SFS and the Andersen FRM and RAAS samplers. All average differences in OC between samplers were less than their respective measurement uncertainties. Positive and negative OC biases were evaluated at Fresno using the Andersen RAAS sampler with carbon-denuded and undenuded channels with Teflon-membrane and quartz-fiber filter pairs. Differences between the denuded particle OC and that obtained by subtracting the quartz-behind-Teflon or quartz-behind-quartz OC from the undenuded quartz-fiber front filter were less than twice their measurement uncertainties in most cases. Particulate OC in the denuded channel agreed most closely with the difference between undenuded front and backup quartz-fiber OC.

Aerosols↗
PubMed2004

Dynamics of volume transmission in the brain. Focus on catecholamine and opioid peptide communication and the role of uncoupling protein 2.

This review focuses on transmitter-receptor mismatches in the brain, which is one of the hallmarks of the Volume Transmission (VT) concept, and how this phenomenon may be related to local temperature gradients created by brain uncoupling protein 2 (UCP2), which uncouples oxidative phosphorylation from ATP synthesis, hereby generating heat. Recent studies on transmitter-receptor mismatches have revealed dopamine and opioid peptide receptor mismatches in the intercalated islands of the amygdala, which are GABAergic cell clusters regulating amygdaloid output. Such mismatches have also been found in regions belonging to the extended amygdala and the nucleus accumbens shell. Now substantial UCP2 immunoreactivity has been found within the above transmitter-receptor mismatch regions, suggesting that UCP2 may enhance diffusion and convection of DA and opioid peptides in such regions by generation of local temperature gradients, thereby contributing to a dynamic regulation of VT.

Animals↗
PubMed2004

Regional crustal thickness and precipitation in young mountain chains.

Crustal thickness is related to climate through precipitation-induced erosion. Along the Andes, the highest mountains and thickest crust (approximately 70 km) occur at 25 degrees south, a region of low precipitation. Westerly winds warm passing over the Atacama Desert; precipitation is modest in the High Andes and eastward over the Altiplano. Severe aridity, hence low erosion rates, helps to account for the elevated volcanogenic contractional arc and high, internally draining plateau in its rain shadow. Weak erosion along the north-central arc provides scant amounts of sediment to the Chile-Peru Trench, starving the subduction channel. Subcrustal removal might be expected to reduce the crustal thickness, but is not a factor at 25 degrees south. The thickness of the gravitationally compensated continental crust cannot reflect underplating and/or partial fusion of sediments, but must be caused chiefly by volcanism-plutonism and contraction. Contrasting climate typifies the terrain at 45 degrees south where moisture-laden westerly winds encounter a cool margin, bringing abundant precipitation. The alpine landscape is of lower average elevation compared with the north-central Andes and is supported by thinner continental crust (approximately 35 km). Intense erosion supplies voluminous clastic debris to the offshore trench, and vast quantities are subducted. However, the southern Andean crust is only about half as thick as that at 25 degrees south, suggesting that erosion, not subcrustal sediment accretion or anatexis, is partly responsible for the thickness of the mountain belt. The Himalayas plus Tibetan Plateau, the Sierra Nevada plus Colorado Plateau, and the Japanese Islands exhibit analogous relationships between crustal thickness and climate.

Journal Article↗
PubMed2005

Long range acoustic imaging of the continental shelf environment: the Acoustic Clutter Reconnaissance Experiment 2001.

An active sonar system is used to image wide areas of the continental shelf environment by long-range echo sounding at low frequency. The bistatic system, deployed in the STRATAFORM area south of Long Island in April-May of 2001, imaged a large number of prominent clutter events over ranges spanning tens of kilometers in near real time. Roughly 3000 waveforms were transmitted into the water column. Wide-area acoustic images of the ocean environment were generated in near real time for each transmission. Between roughly 10 to more than 100 discrete and localized scatterers were registered for each image. This amounts to a total of at least 30000 scattering events that could be confused with those from submerged vehicles over the period of the experiment. Bathymetric relief in the STRATAFORM area is extremely benign, with slopes typically less than 0.5 degrees according to high resolution (30 m sampled) bathymetric data. Most of the clutter occurs in regions where the bathymetry is locally level and does not coregister with seafloor features. No statistically significant difference is found in the frequency of occurrence per unit area of repeatable clutter inside versus outside of areas occupied by subsurface river channels.

Journal Article↗
PubMed2006

[Updated inventory of mosquitoes (Dipbra: Culkidae) from the French islets of Europa, Juan-de-Nova and Grande-Glorieuse (Mozambique channel, Indian Ocean)].

The islets of Europa, Juan-de-Nova and Grande-Glorieuse are French territories isolated in the Mozambique Channel (Indian Ocean) which have remained relatively preserved from anthropization all along their history These three islets have been classified entire nature reserves from 1975 and are today inhabited only by a permanent military detachment of about fifteen men even if they occasionally greet technical and scientific staff. Sanitary and environmental issues brought about assessment of the present culicid fauna. The authors propose a synthesis of the culicid knowledge from the islets and make an inventory of new species. The role played by humans in importation of culicids is discussed as well as sanitary consequences of their adaptation to environment

Aedes↗
PubMed2000

Stratigraphic Analysis of Upper Cretaceous Rocks in the Mahajanga Basin, Northwestern Madagascar: Implications for Ancient and Modern Faunas.

Upper Cretaceous strata of the Mahajanga Basin, northwestern Madagascar, yield some of the most significant and exquisitely preserved vertebrate fossils known from Gondwana. The sedimentology of these strata and their stratigraphic relations have been the focus of renewed geological investigations during the course of five expeditions since 1993. We here designate stratotypes and formalize the terrestrial Maevarano Formation, with three new members (Masorobe, Anembalemba, Miadana), and the overlying marine Berivotra Formation. The Maevarano Formation accumulated on a broad, semiarid alluvial plain bounded to the southeast by crystalline highlands and to the northwest by the Mozambique Channel. The Berivotra Formation was deposited in an open marine setting that evolved from a clastic- to a carbonate-dominated shelf, resulting in deposition of the overlying Betsiboka limestone of Danian age. New stratigraphic data clearly indicate that the Maevarano Formation correlates, at least in part, with the Maastrichtian Berivotra Formation, and this in turn indicates that the most fossiliferous portions of the Maevarano Formation are Maastrichtian in age, rather than Campanian as previously reported. This revised age for the Maevarano vertebrate assemblage indicates that it is approximately contemporaneous with the vertebrate fauna recovered from the Deccan basalt volcano-sedimentary sequence of India. The comparable age of these two faunas is significant because the faunas appear to be more similar to one another than either is to those from any other major Gondwanan landmass. The revised age of the Maevarano Formation, when considered in the light of our recent fossil discoveries, further indicates that the ancestral stocks of Madagascar's overwhelmingly endemic modern vertebrate fauna arrived on the island in post-Mesozoic times. The basal stocks of the modern vertebrate fauna are conspicuously absent in the Maevarano Formation. Finally, the revised age of the Maevarano Formation serves to expand our global perspective on the K/T event by clarifying the age of a diverse, and arguably the best preserved, sample of Gondwanan vertebrates from the terminal Cretaceous.

Journal Article↗
PubMed1984

Graft patency in patients with coronary artery bypass operation complicated by perioperative myocardial infarction.

Coronary artery bypass graft patency was examined by contrast-enhanced computed tomography in 18 patients with perioperative myocardial infarction soon after surgery to determine the role of graft occlusion. Preoperative coronary angiograms were reviewed to assess native coronary disease and visible collateral channels in the distribution of the myocardial infarction. Perioperative myocardial infarction was diagnosed if creatine kinase-MB was elevated, characteristic electrocardiographic changes occurred and, in the majority of cases, the pyrophosphate scan was positive. Fourteen patients (78%) had patent grafts and perioperative myocardial infarction in the distribution of the grafted vessel. Four patients had an occluded graft with infarction in the distribution of the grafted vessel. Among the 14 patients with patent grafts, there was a significant difference (p less than 0.0005) in the degree of the mean (+/- standard deviation) diameter stenosis of 80 +/- 11% in native coronary vessels supplying the perioperatively infarcted myocardium versus a 55 +/- 12% mean diameter stenosis in the 23 bypassed native coronary vessels supplying noninfarcted myocardium. It is concluded that the majority of perioperative myocardial infarcts associated with coronary artery bypass operations are not caused by graft occlusion. The severity of coronary obstruction in the grafted vessel and the lack of collateral vessels to the region of perioperative infarction in patients with patent grafts suggests that an island of jeopardized myocardium exists that is subject to inadequate intraoperative preservation.

Adult↗