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PubMed2004

Contribution of myocardium hydraulic skeleton to left ventricular wall interaction and synergy in dogs.

The most premature motion change after coronary occlusion is early diastolic thinning of the ischemic left ventricular (LV) wall, with concomitant thickening of the normoperfused wall. We aimed 1). to demonstrate that these early changes are the result of the absence of fluid within the ischemic myocardium (hydraulic skeleton) rather than to cell anoxia and 2). to quantitate the contribution of the lack of hydraulic skeleton to left ventricular asynergy of contraction in seven anesthetized dogs submitted to acute, short-lasting circumflex artery (Cx) occlusion (ischemia) and to perfusion of the Cx with an oxygen-free solution (anoxia). We analyzed the time course of regional work index (WI, area of the LV pressure-wall thickness loop) and regional efficiency (defined as the ratio of WI to the maximum possible work). Interwall asynergy was defined as the difference between the regional efficiency of the anterior and posterior walls. After 9-10 s, posterior wall efficiency decreased 37 +/- 6% with anoxia and 72 +/- 3% with ischemia (P < 0.025), and interwall asynergy was 0 +/- 6% with anoxia and 32 +/- 5% with ischemia (P < 0.05). The contribution of absent hydraulic skeleton to interwall asynergy (calculated as the difference between %asynergy in anoxia and %asynergy in ischemia) was 30 +/- 8% (P < 0.05). In conclusion, the earliest wall motion change observed after acute coronary occlusion, namely ischemic wall thinning concomitant with normoperfused wall thickening during isovolumic relaxation, is the result of the absence of intracoronary fluid. The lack of hydraulic skeleton within the myocardium contributes approximately 30% to interwall asynergy.

Animals↗

PubMed1986

Endocardial catheter mapping: wire skeleton technique for representation of computed arrhythmogenic sites compared with intraoperative mapping.

Guiding surgical therapy of ventricular tachycardia by preoperative endocardial catheter mapping necessitates improvement of the accuracy of localization of the arrhythmogenic site. We therefore used a new mathematical cineradiographic method during catheter mapping to compute the position of left ventricular arrhythmogenic sites relative to three anatomic reference points: the centers of aortic and mitral valve ostia and the left ventricular apex. To enable the surgeon to identify the position of the computed sites, a wire skeleton (one for each patient) representing a single or multiple arrhythmogenic site(s) relative to the anatomic reference points was constructed. This wire skeleton was inserted into the left ventricular cavity during surgery. Side branches of the device indicated preoperatively localized arrhythmogenic sites. Results in eight consecutive patients were compared with those of intraoperative simultaneous mapping of 64 endocardial sites. Sixteen morphologically distinct monomorphic ventricular tachycardias were mapped by catheter and 15 by intraoperative mapping. In 12 ventricular tachycardias an identical morphology was recorded during both techniques. The distance between arrhythmogenic sites localized with both methods was 1 cm or less in 11 of these 12 ventricular tachycardias and 2 cm in one ventricular tachycardia. These results indicate that endocardial catheter mapping combined with wire skeleton representation of computed positions of arrhythmogenic sites is reliable for guiding surgical therapy of ventricular tachycardia and since some of the ventricular tachycardias were inducible only during either preoperative or intraoperative mapping, both techniques have an additive value. In addition, the wire skeleton proved convenient during surgery by identifying the arrhythmogenic sites.

Cardiac Catheterization↗

PubMed1981

Altered spectrin dimer-dimer association and instability of erythrocyte membrane skeletons in hereditary pyropoikilocytosis.

Hereditary pyropoikilocytosis (HPP) is a hemolytic anemia characterized by microspherocytosis, poikilocytosis, and an unusual thermal sensitivity of erythrocytes. We have investigated the contribution of abnormal membrane skeletal assembly to these abnormal HPP erythrocyte properties. Skeletons prepared from fresh HPP ghosts with Triton X-100 were considerably more fragile than skeletons from control erythrocytes. Spectrin, the major skeleton component, extracted at 0 degrees C from normal erythrocytes, was present primarily as tetramers and high molecular weight complexes. In contrast, spectrin extracted from HPP erythrocytes under identical conditions contained a significant amount of dimers with a concomitant decrease of tetramers. Furthermore, spectrin dimers from HPP erythrocytes differed from normal spectrin dimers in their failure to reassociate into tetramers both in solution and in the membrane. Presumptive HPP carriers (asymptomatic mothers of the two patients) exhibited a mild but reproducible increase of spectrin dimers in 0 degrees C extracts and a defective reassociation of spectrin dimers of tetramers both in solution and in the membrane. We conclude that in HPP, self-association of spectrin dimers into tetramers is defective, which accounts for the instability of membrane skeletons.

Cytoplasm↗

PubMed1990

The formation of basal body domains in the membrane skeleton of Tetrahymena.

Differentiated regions within the membrane skeleton are described around basal bodies in the ciliary rows of Tetrahymena. These domains, approximately 1 micron in diameter, are characterized by a relatively dense ultrastructure, the presence of a family of proteins called K antigens (Mr 39-44 x 10(3)) that are recognized by mAb 424A8, and the apparent exclusion of major membrane skeleton proteins that are present in most other regions of the cell (Mr 135, 125 x 10(3]. Mature basal body domains are asymmetric, reflecting the polarity of the cell as a whole. A similar differentiation of the membrane skeleton occurs in the oral apparatus, except here the K antigens surround four clusters of basal bodies (from which this cell takes its name) rather than the individual basal bodies. The development of new basal body domains in the cell cycle is described, with similarities and differences noted between somatic and oral regions of the cell. It is concluded that the capacity of this cell for precise topographic regulation of molecular events in the membrane skeleton makes it a useful model for the study of cortical differentiation in cells generally.

Animals↗

PubMed2002

Negative effect of Hox gene expression on the development of the neural crest-derived facial skeleton.

Diencephalic, mesencephalic and metencephalic neural crest cells are skeletogenic and derive from neural folds that do not express Hox genes. In order to examine the influence of Hox gene expression on skull morphogenesis, expression of Hoxa2, Hoxa3 and Hoxb4 in conjunction with that of the green fluorescent protein has been selectively targeted to the Hox-negative neural folds of the avian embryo prior to the onset of crest cell emigration. Hoxa2 expression precludes the development of the entire facial skeleton. Transgenic Hoxa2 embryos such as those from which the Hox-negative domain of the cephalic neural crest has been removed have no upper or lower jaws and no frontonasal structures. Embryos subjected to the forced expression of Hoxa3 and Hoxb4 show severe defects in the facial skeleton but not a complete absence of facial cartilage. Hoxa3 prevents the formation of the skeleton derived from the first branchial arch, but allows the development (albeit reduced) of the nasal septum. Hoxb4, by contrast, hampers the formation of the nasal bud-derived skeleton, while allowing that of a proximal (but not distal) segment of the lower jaw. The combined effect of Hoxa3 and Hoxb4 prevents the formation of facial skeletal structures, comparable with Hoxa2. None of these genes impairs the formation of neural derivatives of the crest. These results suggest that over the course of evolution, the absence of Hox gene expression in the anterior part of the chordate embryo was crucial in the vertebrate phylum for the development of a face, jaws and brain case, and, hence, also for that of the forebrain.

Animals↗

PubMed1987

Evidence that tubulin forms an integral membrane skeleton in molluscan gill cilia.

Controlled extraction of intact gill tissue, isolated cilia or reconstituted membrane vesicles with Nonidet P-40 at greater than 4 times the critical micelle concentration, or with octyl glucoside at the critical micelle concentration, delipidates the membrane, leaving a membrane remnant or skeleton of membrane tubulin and associated proteins. This skeleton consists of a disordered reticular protein network in reconstituted membrane vesicles and a similar but more compact sleeve in cilia of extracted tissue. The membrane skeleton is closely apposed to the axoneme and is attached to the outer doublets by fine radial bridges having a 20-24 nm longitudinal periodicity, supporting earlier observations made utilizing a lipophilic cross-linking agent. Higher concentrations of detergent solubilize the membrane tubulin-protein complex, producing 5-10 nm particulate material of low sedimentation coefficient. Dilution of an octyl glucoside solution to below the critical micelle concentration results in disappearance of the particles and reformation of the membrane, indicating that the particles are protein-detergent micelles and not denatured protein. Freeze-fracture electron microscopy reveals no comparable-sized natural particles in the ciliary membrane proper. The reticular material of the membrane skeleton contains tubulin, demonstrated on Lowicryl K4M thin sections by a rabbit polyclonal antibody to sea-urchin egg cytoplasmic tubulin, using gold-labelled secondary antibody. Minimal cross-reactivity is detected prior to Triton-delipidation, suggesting that most membrane tubulin antigenic sites are buried within the bilayer and that the tubulin is not simply adsorbed to the lipid bilayer.

Animals↗

PubMed2002

Three-dimensional-line skeleton graph analysis of high-resolution magnetic resonance images: a validation study from 34-microm-resolution microcomputed tomography.

The resolution achievable in vivo by magnetic resonance imaging (MRI) techniques is not sufficient to depict precisely individual trabeculae and, thus, does not permit the quantification of the "true" trabecular bone morphology and topology. Nevertheless, the characterization of the "apparent" trabecular bone network derived from high-resolution MR images (MRIs) and their potential to provide information in addition to bone mineral density (BMD) alone has been established in studies of osteoporosis. The aim of this work was to show the ability of the three-dimensional-line skeleton graph analysis (3D-LSGA) to characterize high-resolution MRIs of trabecular bone structure. Fifteen trabecular bone samples of the distal radius were imaged using the high-resolution MRI (156 x 156 x 300 microm3) and microcomputed tomography (microCT; 34 x 34 x 34 microm3). After thresholding, the 3D skeleton graph of each binary image was obtained. To remove the assimilated-noise branches of the skeleton graph and smooth this skeleton graph before it was analyzed, we defined a smoothing length criterion (l(c)), such that all "termini" branches having a length lower than l(c) were removed. Local topological and morphological LSGA measurements were performed from MRIs and microCT images of the same samples. The correlations between these two sets of measurements were dependent on the smoothing criterion l(c), reaching R2 = 0.85 for topological measurements and R2 = 0.57-0.64 for morphological measurements. 3D-LSGA technique could be applied to in vivo high-resolution MRIs of trabecular bone structure, giving an indirect characterization of the microtrabecular bone network.

Adult↗

PubMed2004

Off-Pump Coronary Artery Bypass Using Skeletonized Gastroepiploic Artery, a Pilot Study.

Abstract Background: The problem with using the gastroepiploic artery (GEA)for coronary artery bypass grafting (CABG) is vasospasm. To minimize vasospasm of the GEA, a skeletonized harvesting technique was used for GEA harvesting. We present the initial results of GEA grafting using this technique. Methods: Between September 1, 2002, and December 31, 2002, a total of 25 patients (21 men and 4 women, mean age 65.4 +/- 8.7 years) gave informed consent and underwent elective off-pump CABG using the skeletonized GEA. Skeletonization was completed using an ultrasonic scalpel (Harmonic scalpel, coagulating-scissors; Ethicon Endo-Surgery, Cincinnati, OH, USA). Follow-up data were available until August 31, 2003. Perioperative, early clinical, and follow-up results were analyzed. Results: There were no hospital deaths, perioperative myocardial infarctions, congestive heart failure, strokes, or renal failure. There were no abdominal complications. Follow-up data were available from all patients, with a mean follow-up of 0.8 +/- 0.1 years. There were no cardiac deaths or cardiac events. Conclusion: During our limited follow-up period, the early results of skeletonized GEA grafting were excellent, and cardiac events have been well controlled. Mid-term follow-up study and angiographic study are necessary to confirm our initial clinical outcome data.

Journal Article↗

PubMed2003

Skeletonization of the radial artery with the ultrasonic scalpel: clinical and angiographic results.

BACKGROUND: To improve the patency rate of the radial artery graft, we have been using a skeletonized harvesting technique since September 1, 2001. Our early reports confirmed better graft patency of the skeletonized radial graft than the conventional pedicled graft. However, its midterm results were unknown. We present our recent experience and follow-up results of radial artery grafting using the skeletonized harvesting technique. METHODS: Between September 1, 2001, and July 31, 2002, 391 patients underwent isolated coronary artery bypass surgery in our hospital group, excluding minimally invasive direct coronary bypass procedures via small thoracotomy or T-grafting. Among them, skeletonized radial grafting was performed in 246 patients (182 men and 64 women; mean age, 66.2 +/- 9.5 years). Follow-up is to be completed by December 31, 2003. Perioperative, early angiographic, and follow-up results were analyzed. RESULTS: There were 1 hospital death and 5 incidences of postoperative myocardial infarction. None of these occurrences were related to radial artery bypass. Early angiography revealed that the stenosis-free graft patency rate of radial artery anastomoses (291/303 cases, 96.0%) was not significantly different from the patency rates of surgeries involving the use of other conduits (left internal mammary artery, 95.1%; right internal mammary artery, 93.8%; gastroepiploic artery, 93.1%; and saphenous vein, 98.2%). Follow-up was completed for all hospital survivors with a mean follow-up time of 1.4 +/- 0.3 years. There were no cardiac deaths and 5 cardiac events, giving a cardiac event-free rate of 97.5%. CONCLUSION: In our limited follow-up, cardiac events have been well controlled. Midterm follow-up angiographic study is necessary to confirm our clinical outcome data.

Adult↗

PubMed2004

Skeletonized radial artery grafting: one-year patency rate.

BACKGROUND: The skeletonized radial artery harvesting technique has routinely been used in our institute. Its clinical outcome is acceptable; however, the graft patency rate at 1 year has not been reported. METHODS: Between July 1, 2003, and October 31, 2002, 50 consecutive patients underwent isolated coronary artery bypass using skeletonized radial artery grafts in our hospital. There were no hospital deaths or perioperative myocardial infarctions. All patients completed follow-up by November 2003. Twenty of these patients (18 asymptomatic volunteers and 2 symptomatic patients) underwent coronary angiography at 1 year, and the results were analyzed. RESULTS: At a mean (+/-SD) follow-up period of 1.2 +/- 0.2 years, there were no deaths. Two patients developed angina due to graft occlusion (1 in the radial artery and another in the gastroepiploic artery). Twenty-one radial artery grafts and 36 distal anastomoses with radial artery grafts were evaluated by angiography at 1 year (0.9 +/- 0.1 years). There was 1 radial artery graft occlusion affecting 1 distal anastomosis, giving a perfect graft patency rate of 95.2% (20/21) and a perfect anastomosis patency rate of 97.2% (35/36). The patient with the occluded radial artery graft had a history of peripheral vascular disease and diabetes. There were no graft stenoses or string signs. CONCLUSION: At our limited follow-up, the results of using skeletonized radial artery grafts are excellent. Extensive skeletonization will not affect the graft patency rate or early graft spasm. Careful examinations of the radial artery grafts in patients with a history of peripheral artery disease and diabetes are mandated.

Aged↗

PubMed1976

Effect of a skeleton photoperiod on the daylength-dependent response to oestrogen in canaries (Serinus canarius).

Previous studies have shown that ovariectomized canaries, injected with 50 mug oestradiol benzoate thrice weekly, show more oestrogen-induced nest-building on a long day than on a short day. In this study the same effect was obtained with castrated canaries. The influence of time available for building was assessed first by comparing castrated males on skeleton long days with birds on short days, the total number of light hours being equal. More birds in the skeleton long-day group placed material in the nest, and did so with a shorter latency, than birds in the short-day group. Thus the differences between short- and long-day birds are unlikely to be due entirely to differences in the time available. However, some of the long-day birds were no more active than the short-day ones suggesting that the skeleton long-day schedule does impose some constraint. In a third experiment photorefractory females (whose ovaries do not secret oestrogen in response to long days) kept on a long skeleton-day scored similarly on all measures of building as birds kept on a full 14 h day and significantly more than birds on a short day. The results also indicate that the birds are measuring daylength by means of a diurnal rhythm of photosensitivity, an effect comparable to that of longer photoperiods on gonadal growth.

Animals↗

PubMedDate not supplied

Retrospective analysis of axial skeleton osteosarcoma in 22 large-breed dogs.

Medical-records of 22 large-breed dogs (>15 kg) with osteosarcoma (OSA) of the axial skeleton were reviewed to determine prevalence of metastasis and survival associated with this neoplasm. All dogs were treated with more than 1 mode of therapy including palliative radiation (n = 12), definitive radiation (n = 8), surgery (n = 7), chemotherapy (n = 12), or some combination of these therapies. Metastasis was documented in 10 of 22 dogs (46%), and the median survival for all dogs was 137 days. Primary cause of death was local tumor recurrence (54%). Breed (retriever versus purebred versus mixed-breed survival was 100, 182, and 264 days, respectively) and radiation therapy protocol (survival in dogs treated with palliative radiation therapy versus those treated with definitive radiation therapy was 79 and 265 days, respectively) were significantly related to survival (P < .05). Prevalence of metastasis and median survival for large-breed dogs with axial skeleton OSA seems to be similar to that reported for large-breed dogs with appendicular skeleton OSA. Definitive radiation therapy may have a role in the treatment of axial skeleton osteosarcoma.

Animals↗

PubMed1997

Relationship between free-running period and minimum tolerable light pulse interval of skeleton photoperiods in field mice Mus booduga.

The entrainment of the circadian rhythm of locomotor activity was studied in the field mouse Mus booduga in order to examine the relationship between the free-running period (tau) and minimum tolerable light pulse interval of the skeleton photoperiods. The animals were entrained under three different light/dark (LD) schedules, each out of phase with the other. They were then subjected to various skeleton photoperiods created by two repeated light pulses (LPs) interrupting darkness. Animals that selected the shorter interval between the LPs as their "subjective night" had significantly shorter tau (23.13 +/- 0.38 h) as compared to those that selected the longer dark interval as subjective night (tau = 23.87 +/- 0.18 h). When the longer dark interval was 12 h, animals selecting that interval as their subjective night included both long-tau and short-tau individuals. When both intervals of darkness were of equal duration, no difference in the selection of subjective night was seen between short and long-tau animals. When the "dusk" LP for the animals that selected the longer dark interval as subjective night was advanced by 2 h to create a new skeleton photoperiod, the number of transient cycles appearing before steady-state entrainment was found to depend on the duration of the photoperiods. When the night defined by the two LPs was reduced below 6h, a dramatic "phase jump" in the activity rhythm was observed, and the initial phase relationship was restored after a relaxation in the night duration. We observed considerable interindividual variation in the "minimum tolerable light pulse interval of skeleton photoperiods," which we suggest may be due to the observed variation in tau among individuals.

Animals↗

PubMed2000

The effects of short-time caffeine administration on skeleton development in Wistar rats.

The aim of the study was to evaluate the influence of caffeine on skeleton ossification in rats. Caffeine was administered in Tween 80 solution, once daily, in oral bolus, during the whole second trimester, in three doses: C1--0.7 mg/kg, C2--7.0 mg/kg, C3--70.0 mg/kg. On the 21st day of gestation the pumps were delivered. The fetuses were fixed in Bouin's solution and subsequently observed for external and internal malformation or in alcohol for skeleton malformation. The skeletons were stained with alizarin red-S. The examination showed an insignificant (P < 0.05) number of skeleton malformations, external haematomas and any internal malformations.

Animals↗

PubMedDate not supplied

Myocardial revascularization with skeletonized left mammary artery.

Graft selection has a direct influence on overall morbidity and mortality in patients selected for coronary artery bypass grafting (CABG) procedures. In the last decade internal mammary artery has been established as a conduit of choice for myocardial revascularization. However, there is still no official policy which operative technique has advantage in harvesting of the internal mammary artery (IMA). Current dilemma is whether pedicle or skeletonized grafts are better in immediate and long term results. Method of skeletonization of IMA increases surgeon's technical demands, but on the other hand has many advantages. Precise operative technique and selective preparation of IMA without concomitant elements reduces trauma to the chest wall, enables elongation and ideal graft positioning, and reduces graft compression by hyperinflated lungs. Complete graft visualization allows inspection of internal mammary artery in entire length, which excludes possibility to implant dissected or hypoplastic graft. From June 1996 we started using the method of skeletonization of IMA, and until February 1st 1999 skeletonized IMA was used as a conduit in 1001 patients. In our hands myocardial revascularization with IMA is a procedure with minimal morbidity and mortality. Precise operative technique during the harvesting of IMA is advantage especially in diabetics, old patients and patients with chronic obstructive pulmonary disease (COPD), that were considered as limiting factors for IMA use in the past. Our initial results with the quality of this conduit encourage us to extend the indication for using IMA as a dominant graft in multiple myocardial revascularization.

Adult↗

PubMed2001

Mechanoprotection of the plasma membrane in neurons and other non-erythroid cells by the spectrin-based membrane skeleton.

Though the cytomechanics of spectrin have been explored only for erythrocytes, it is thought that the spectrin skeleton acts universally to support the otherwise mechanically vulnerable cell surface bilayer. Evidence for this role is beginning to accumulate and is reviewed here. Compared to that for erythrocytes, cells whose simplicity facilitates biophysical approaches, the evidence is indirect. One way that membrane skeleton/bilayer interactions have been probed is via the behavior of mechanosusceptible ion channels - channel whose gating is perturbed by abnormally high bilayer tension. These initially unresponsive channels become progressively more mechanoresponsive as stretch and chemical reagents damage the membrane skeleton. The straightforward implication is that the intact membrane skeleton is mechanoprotective. In non-erythroid cells there is continual trafficking of bilayer to and from the plasma membrane. Some of the traffic involves spectrin-lined vacuolar membrane. Several lines of evidence suggest that when neurons elongate and remodel their neurites, membrane skeleton-based mechanoprotection allows the dynamic vacuoles and the plasma membrane to participate in mechanosensitive surface area expansion and retrieval.

Animals↗

PubMed2001

Biomedical image skeletonization: a novel method applied to fibrin network structures.

To understand the rheological behavior of fibrin clots, we must obtain quantitative measurements of morphometric parameters of the networks formed under various conditions. The networks are so complex that researchers must currently manually segment the images of network samples and estimate the parameters from them. Skeletonization is a promising tool for automating this task. We here propose a method that rapidly constructs a coarse representation of a skeleton graph and, using the snake model, deforms the graph to obtain smooth skeletons. Unlike many existing approaches, our method does not involve explicit object boundary information or high order derivatives. Since our method processes a given image as a whole, the presence of multiple objects in an image is automatically detected and the skeletons of these objects are computed simultaneously.

Algorithms↗

PubMed2002

[Goethe's skull and skeleton].

In 1970 there was a conservation of Goethe's skeleton, housed in the Fürstengruft in Weimar. This procedure was kept secret until 1999. The restoration of the sarcophagus and the conservation of the skeleton have been documented together with many photos in the so-called "Sonderakte Mazeration Goethe" (special file mazeration Goethe). In this special file there are also photos of Goethe's skull and skeleton which will be published here for the first time and analysed under anthropological and palaeopathological aspects. A short description of the skull will be given. The dentition of Goethe at the time of his death and the question of progenia in Goethe's family are discussed in detail. Data on Goethe's stature obtained from the skeleton qualify statements of Goethe's contemporaries. Among the few documented pathological changes the ankylosis of eight thoracal vertebrae (T 5-12) and five right ribs are of special interest, caused by the loss of the intervertebral discs, spondylosis deformans and Morbus Forestier. A connection between this ankylosis and the known stiff posture and stiff gait of Goethe is obviously and possibly dates back to Goethe's fortieth years of age.

Famous Persons↗