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At least 793 records · Page 44Linked to original sources
PubMed2006

Transformation of the pectoral girdle in the evolutionary origin of frogs: insights from the primitive anuran Discoglossus.

Using cleared-and-stained whole mounts and computer-aided three-dimensional reconstructions made from serial histological sections, we studied the development of the pectoral girdle in Discoglossus pictus, an extant member of an ancient frog lineage, represented for example by Eodiscoglossus from the Middle Jurassic to Early Cretaceous periods in Europe. Basic developmental features were compared with those of extinct Temnospondyli, considered to be the most probable anuran ancestors, and with Triadobatrachus, an early Triassic proanuran. In the endochondral girdle, the separate scapula and coracoid of Discoglossus and other anurans (completed by suprascapular and procoracoid cartilages) evolved from the compact scapulocoracoid of temnospondyls by paedomorphosis. In parallel, the dermal ossifications of the girdle were reduced to a small clavicle and cleithrum. The overall reduction in ossification of the anuran pectoral girdle supports the hypothesis of a paedomorphic origin for Anura. The almost simultaneous appearance of dermal and endochondral ossifications may be explained by the accumulation of developmental events during a short, distinct metamorphosis (which did not occur in neotenic temnospondyls living permanently in water). The sternal elements seem to be neomorphs for the most part, which help to cushion the shock of landing in jumping anurans but which also evolved as functional substitutes (insertion area for the pectoralis muscles) of the temnospondyl interclavicle.

Animals↗
PubMed1985

Myopotential inhibition of unipolar pacing in children.

Myopotential inhibition of unipolar demand pacing systems has been shown to be a frequent occurrence in adults with transvenous pacing systems in which the pulse generators are implanted adjacent to the pectoralis muscle. To evaluate this problem in children, most of whom have epimyocardial systems and abdominal wall generator implants, 50 patients underwent electrocardiographically monitored exercise and 24-hour ambulatory electrocardiograph monitoring. Patients' ages at the time of study ranged from less than one year to 18 years, and weights ranged from less than 5 kg to 63 kg. Sixteen different models of pulse generators from five manufacturers were involved. Pacing modes were VVI, DVI, AAI, VDD, and DDD. Forty-seven patients had epimyocardial systems. None of the patients was symptomatic as a result of myopotential inhibition. Only three patients (6%) had any evidence of myopotential inhibition and all three demonstrated this inhibition on both monitored exercise and ambulatory electrocardiograph. The inhibition was eliminated by reprogramming the sensitivity levels of the three generators without compromising R-wave sensing. Thirteen of the remaining 35 patients with multiprogrammable generators had induction of myopotential inhibition when exercised after temporary programming to maximal sensitivity settings. Myopotential inhibition of unipolar demand pacing appears to be less frequent and less problematic in the pediatric population, even though they are physically quite active. It is not clear whether this is a function of patient size or the abdominal wall position of the pulse generator.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗
PubMed1988

Rate dependent depression of subsidiary ventricular impulse formation--cause of Stokes-Adams attacks in a patient with rate modulated pacing.

Following His bundle ablation and implantation of a rate adaptive pacemaker (Vitatron TX 911) a 52-year-old gentleman experienced several presyncopal attacks while driving a car. On examination pectoralis muscle contraction caused temporary pacemaker inhibition. Incremental overdrive stimulation demonstrated progressive depression idioventricular automaticity and was associated with similar symptoms following overdrive at high pacing rates. Following appropriate pacemaker programming the patient remained symptom free.

Adams-Stokes Syndrome↗
PubMed1992

Macromastia as a factor in sternal wound dehiscence following cardiac surgery: management combining chest wall reconstruction and reduction mammoplasty.

Major sternal wound infection occurs in nearly 2% of patients following coronary artery bypass graft surgery. The relationship of this complication to gender has not been reported in detail, nor has female breast size previously been implicated as a factor increasing the risk of sternotomy dehiscence. We report two cases of sternotomy wound dehiscence in women with large, pendulous breasts undergoing myocardial revascularization surgery and postulate that the weight of large, unsupported breasts produced inferolateral tension on the midline sternotomy incisions, contributing to dehiscence of the wounds. Chest wall reconstruction was accomplished using pectoralis muscle flaps, and the procedures were combined with amputative reduction of the size of the breasts, with subsequently successful healing in each case. Combining sternal reconstruction with breast reduction surgery may lead to improved secondary outcome, and postoperative use of supportive brassieres may reduce the frequency of this complication.

Aged↗
PubMed2001

MR imaging-guided focused ultrasound surgery of fibroadenomas in the breast: a feasibility study.

PURPOSE: To test the feasibility of noninvasive magnetic resonance (MR) imaging-guided focused ultrasound surgery (FUS) of benign fibroadenomas in the breast. MATERIALS AND METHODS: Eleven fibroadenomas in nine patients under local anesthesia were treated with MR imaging-guided FUS. Based on a T2-weighted definition of target volumes, sequential sonications were delivered to treat the entire target. Temperature-sensitive phase-difference-based MR imaging was performed during each sonication to monitor focus localization and tissue temperature changes. After the procedure, T2-weighted and contrast material-enhanced T1-weighted MR imaging were performed to evaluate immediate and long-term effects. RESULTS: Thermal imaging sequences were improved over the treatment period, with 82% (279 of 342) of the hot spots visible in the last seven treatments. The MR imager was used to measure temperature elevation (12.8 degrees -49.9 degrees C) from these treatments. Eight of the 11 lesions treated demonstrated complete or partial lack of contrast material uptake on posttherapy T1-weighted images. Three lesions showed no marked decrease of contrast material uptake. This lack of effective treatment was most likely due to a lower acoustic power and/or patient movement that caused misregistration. No adverse effects were detected, except for one case of transient edema in the pectoralis muscle 2 days after therapy. CONCLUSION: MR imaging-guided FUS can be performed to noninvasively coagulate benign breast fibroadenomas.

Adult↗
PubMed1981

Trophic effect of a sciatic nerve extract on fast and slow myosin heavy chain synthesis.

Myosin heavy chain (MHC) synthesis in cultures from chick pectoralis muscle cells was determined by [35S]methionine incorporation. Two types of MHC, migrating as 200,000-dalton components on sodium dodecyl sulfate polyacrylamide gels, were distinguished with antibodies against adult fast and slow MHC. Their synthesis was revealed by autoradiography. The effect of a sciatic nerve extract on the synthesis of the two types of MHC was also determined. Control experiments show that fast MHC is primarily synthesized in 48-h cultures. At a later stage of development (5- to 7-day cultures), slow MHC is also produced. The nerve extract promotes muscle cell differentiation and stimulates the synthesis of the slow type of MHC at an earlier stage of development (i.e., at 48 h as compared with 5-7 day in controlled cultures). It is concluded therefore that presumptive fast muscle cells in culture synthesize initially fast MHC and later both types of MHC (slow and fast). These results also suggest that the sciatic nerve extract is capable either of activating the transcription of the structural gene for slow MHC or of activating the translation of preexisting messenger RNA coding for this protein.

Animals↗
PubMed1991

Mitochondrial DNA replication and transcription are dissociated during embryonic cardiac hypertrophy.

Cardiac hypertrophy was produced in embryonic chicks by decreasing the incubation temperature from 38 degrees C to 32 degrees C on day 11. Increases in ventricular protein, RNA, and DNA support the cardiac enlargement. Cytochrome-c oxidase activity and citrate synthase activity were depressed in hypothermic ventricles by 63% and 56%, respectively. No significant differences were seen in enzyme activities in pectoralis muscles. The involvement of mitochondrial gene replication and transcription was evaluated using a cDNA clone for the mitochondrially encoded subunit III of cytochrome-c oxidase (CO III). Quantitative slot-blot analysis demonstrated that the relative CO III mRNA concentration was reduced in hypothermic ventricles. In contrast, the relative mitochondrial DNA concentration was increased in hypothermic ventricles. Taken together, these data indicate that a hypothermia-induced decrease in cytochrome-c oxidase activity is associated with a decrease in CO III mRNA, which is not coupled to a decrease in the mitochondrial DNA copy number. This dissociation of mitochondrial gene replication and transcription may provide a useful model for examining the regulation of mitochondrial biogenesis.

Amino Acid Sequence↗
PubMed2003

Acquired perforating dermatosis in a patient with Poland syndrome.

Acquired perforating dermatosis (APD) is characterized by umbilicated 1- to 10-mm-measuring papulonodules with a central adherent oystershell-like keratotic plug, typically on the dorsa of the hands, forearms and over the knees. APD is associated with systemic diseases, especially diabetes mellitus and/or renal failure. Histologically the lesions show transepidermal elimination of altered dermal components into a cup-shaped epidermal depression. We present a 69-year-old man with coexisting APD and Poland syndrome (PS), an association not yet described. PS (OMIM 173800) is a rare congenital anomaly consisting of unilateral partial or total absence of the greater pectoralis muscle and ipsilateral symbrachydactyly. Most cases of PS are sporadic as it was in our case. Our patient had, in addition, an untreated diabetic condition, hyperuricaemia, dilated cardiomyopathy and a very recent pulmonary embolism. He responded to therapy with allopurinol.

Aged↗
PubMed2004

Breast cancer development in a female with Poland's syndrome.

BACKGROUND: Poland's syndrome, a rare congenital anomaly characterized by a defect of the pectoralis muscles, has been reported in association with lymphoreticular malignancies and some solid tumors. CASE REPORT: We report the case of a 53-year-old woman with Poland's syndrome who developed breast cancer in the afflicted ipsilateral hypoplastic breast. FNA cytology revealed a moderately differentiated carcinoma and histology was consistent with a well differentiated invasive ductal carcinoma. CONCLUSION: Poland's syndrome can be associated with breast cancer so all females with the syndrome should be thoroughly examined for early detection of neoplasia.

Breast Neoplasms↗
PubMed1982

Function of the subclavius muscle in a nonhuman primate, the spider monkey (Ateles).

Within the primate order, the morphology of the subclavius muscle is known to be unique among the prehensile-tailed South American monkeys. 3 spider monkeys, Ateles, were monitored electromyographically to determine the recruitment of this muscle during various locomotor and postural activities. Rather than indicating a static stabilizing function, which has typically been inferred from classical anatomical studies, results from this study suggest that the subclavius performs more as a dynamic element in movements of the pectoral girdle during brachiation, vertical climbing, pronograde quadrupedalism and leaping. Complementary activity patterns were also identified between the subclavius and the caudal fibers of the trapezius indicating that the subclavius is used when the animal must depress, or resist cranial displacement, of the protracted shoulder girdle, while the caudal trapezius is recruited when the girdle is retracted on the chest wall.

Animals↗
PubMed1981

Diaphragmatic and genioglossal electromyogram responses to isocapnic hypoxia in humans.

In order to define the relationship between central control of upper airway and respiratory muscle function, diaphragmatic electromyogram (EMGdi) and genioglossal EMG (EMGge) responses to isocapnic hypoxia were studied in 6 awake supine volunteers. Both EMGs were processed and quantitated as moving time average activity. In all subjects, EMGge showed phasic inspiratory activity synchronous with EMGdi. Increases seen in EMGdi and EMGge were linearly related to the decrease in oxygen saturation (r = 0.89 +/- 0.08 and 0.89 +/- 0.08, respectively). There was also a linear relationship between the relative responses of both EMGs to hypoxia such that a low EMGdi response was associated with a low EMGge response and vice versa (r = 0.92, p less than 0.001). These results indicated that the genioglossus muscle behaves like a respiratory muscle and suggested that central control of upper airway and respiratory muscles in humans are intimately related.

Carbon Dioxide↗
PubMedDate not supplied

Spontaneous retraction of indwelling catheters: previously unreported complications.

The development of totally implantable reservoir central venous access systems has been an important advance in patients requiring long-term central venous access. With lower rates of infection and thrombosis than those with external catheters, they have potential for greater longevity and patient acceptance. Complications such as subcutaneous prosthetic infection, infusate extravasation, and difficulty in locating and puncturing the port have been reported. We present two cases of catheter migration and withdrawal from the subclavian vein. This presumably occurred from the action of the underlying pectoralis muscle on the reservoir, as well as a "jetting effect" during flushing. We make suggestions for prevention of similar problems in the future.

Adult↗
PubMed1997

The effects of the wingbeat cycle on respiration in black-billed magpies (Pica pica)

Interclavicular and posterior thoracic airsac pressures, tracheal airflows and pectoralis muscle activity were recorded simultaneously to determine the effect of the wingbeat cycle upon the function of the respiratory system. The effects of the wingbeat cycle on the relative positions of thoraco-abdominal skeletal structures were also assessed using high-speed X-ray cinematography of magpies Pica pica flying in a windtunnel. We found that the furcula bends laterally on the downstroke and recoils medially on the upstroke, as previously described for starlings, and that the coraco-sternal joint (the most consistently visible point on the sternum for digitization) is displaced dorsally during the downstroke and ventrally, with respect to the vertebral column, during the upstroke. In magpies, there are generally three wingbeat cycles during a respiratory cycle. When downstroke occurs during inspiration, its compressive effect reduces the inspiratory subatmospheric airsac pressure by an average of 92 % (0.35 kPa), whereas when upstroke occurs during expiration its expansive effect can reduce the expiratory supra-atmospheric airsac pressure by 63 % (0.23 kPa). Corresponding changes occur in tracheal airflow. Changes in respiratory parameters during short flights with respect to resting values include a doubling of tidal volume and a tripling of respiratory frequency. We conclude that the wingbeat cycle can have a substantial impact on respiratory system function in the flying magpie, and that this represents a mechanical basis for breathing patterns and patterns of phasic coordination between wingbeat and respiratory cycles that may result in minimal interference and maximal assistance from the wingbeat upon the respiratory cycle.

Journal Article↗
PubMed2000

Horizontal flight of a swallow (Hirundo rustica) observed in a wind tunnel, with a new method for directly measuring mechanical power.

A swallow flying in the Lund wind tunnel was observed from the side and from behind, by two synchronised high-speed video cameras. The side-view camera provided a record of the vertical position of a white mark, applied to the feathers behind and below the eye, from which the vertical acceleration was obtained. The rear-view camera provided measurements of the mean angle of the left and right humeri above horizontal. From these data, the force acting on the body, the moment applied by each pectoralis muscle to the humerus and the rotation of the humerus were estimated and used to analyse the time course of a number of variables, including the work done by the muscles in each wing beat. The average mechanical power turned out to be more than that predicted on the basis of current estimates of body drag coefficient and profile power ratio, possibly because the bird was not flying steadily in a minimum-drag configuration. We hope to develop the method further by correlating the mechanical measurements with observations of the vortex wake and to apply it to birds that have been conditioned to hold a constant position in the test section.

Animals↗