Initial experience with breast reconstruction using the transverse rectus abdominis myocutaneous flap: a study of 45 patients.
Breast conserving surgery for breast cancer has led to an increased interest in reconstruction following mastectomy. The transverse rectus abdominis myocutaneous flap has been proven to give good results in terms of restoration of body symmetry with near normal contour and consistency. Furthermore, immediate reconstruction has the advantage of a single procedure with less psychological morbidity, and reduction in hospital stay and overall complication rate. The aim of this study was to review our experience with the transverse rectus abdominis myocutaneous flap procedure an initial series of 45 patients. The overall complication rate of 27% is similar to that reported in the literature, with no total flap loss and nine patients with partial flap loss. There was no delay in commencement of adjuvant chemotherapy or radiotherapy and we believe our ability to detect local recurrence has not been compromised. We consider that immediate breast reconstruction is now an integral part of the surgical treatment of breast cancer. (+info)
Possible postsynaptic action of aminoglycosides in the frog rectus abdominis.
The present study was undertaken to investigate the postsynaptic effects of aminoglycosides on contractions evoked by acetylcholine (ACh), KCl, electrical field stimulation (EFS) and Na(+)- and Ca(2+)-free Ringer solution with 0.2 mM Na2 EDTA (NaFCaFR) in the isolated frog rectus abdominis. Neomycin inhibited contraction elicited by ACh, NaFCaFR, and EFS at the higher frequencies (8 and 10 Hz) but not those elicited by KCl and EFS at the lower frequencies (2, 3 and 5 Hz). D-tubocurarine inhibited ACh-induced contractions in a concentration-dependent manner. In addition, drug reduced EFS-evoked contractions to a limited extent. Lower concentrations (10(-5), 5 x 10(-5), 10(-4), 2 x 10(-4) and 3 x 10(-4) M) but not higher concentrations (4 x 10(-4) and 5 x 10(-4) M) of methoxyverapamil exhibited a concentration-dependent inhibitory action on NaFCaFR-induced contractions. Similar inhibitions of the same type of contraction were displayed by aminoglycosides (neomycin, streptomycin, netilmycin, gentamycin and amikacin). These results suggest that in addition to their antagonistic action on nicotinic receptors in the frog rectus abdominis, aminoglycosides may exert stabilizing effects on some functional components contributing to contractions at the membrane. (+info)
Stretch reflexes in the rectus abdominis muscle in man.
The spinal reflex circuitry of the rectus abdominis (RA) muscle in man was investigated by the application of a mechanical tap to the muscle. Electromyographic recordings were made in ten healthy subjects, performing a series of manoeuvres, using pairs of surface electrodes placed bilaterally. The reflex responses elicited largely depended on the amount of tonic (postural) activity of the trunk. When standing in the upright position, no reflex activity was recorded in response to the tap. Reflex activity due to mechanical tap was readily recorded when the muscle became tonically active. Moderate, backward trunk extension introduced short-latency reflexes at 18.8 +/- 1.9 ms (mean +/- S.D.) ipsilaterally and 20.8 +/- 1.8 ms contralaterally. Excitatory reflex activity of longer latency was also recorded contralaterally in all subjects (latency 45.1 +/- 4.3 ms) and ipsilaterally in five of the ten subjects (latency 47.2 +/- 2.6 ms). Vibration of the tapped muscle produced a reduction in the amplitude of the early reflex responses, whilst increasing the amplitude of the late responses. Moreover, the early reflexes were facilitated by the Jendrassik manoeuvre. Such observations are consistent with the early responses being mediated, at least partly, monosynaptically, and the late responses being of polysynaptic nature. This implies that muscle spindle afferents from rectus abdominis monosynaptically activate motoneurones contralaterally. (+info)
Definition of neuronal circuitry controlling the activity of phrenic and abdominal motoneurons in the ferret using recombinant strains of pseudorabies virus.
During a number of behaviors, including vomiting and some postural adjustments, activity of both the diaphragm and abdominal muscles increases. Previous transneuronal tracing studies using injection of pseudorabies virus (PRV) into either the diaphragm or rectus abdominis (RA) of the ferret demonstrated that motoneurons innervating these muscles receive inputs from neurons in circumscribed regions of the spinal cord and brainstem, some of which have an overlapping distribution in the magnocellular part of the medullary reticular formation (MRF). This observation raises two possibilities: that two populations of MRF neurons provide independent inputs to inspiratory and expiratory motoneurons or that single MRF neurons have collateralized projections to both groups of motoneurons. The present study sought to distinguish between these prospects. For this purpose, recombinant isogenic strains of PRV were injected into these respiratory muscles in nine ferrets; the strain injected into the diaphragm expressed beta-galactosidase, whereas that injected into RA expressed green fluorescent protein. Immunofluorescence localization of the unique reporters of each virus revealed three populations of infected premotor neurons, two of which expressed only one virus and a third group that contained both viruses. Dual-infected neurons were predominantly located in the magnocellular part of the MRF, but were absent from both the dorsal and ventral respiratory cell groups. These data suggest that coactivation of inspiratory and expiratory muscles during behaviors such as emesis and some postural adjustments can be elicited through collateralized projections from a single group of brainstem neurons located in the MRF. (+info)
A comparative study of aging of the elastic fiber system of the diaphragm and the rectus abdominis muscles in rats.
In the present study the age-related changes of the striated muscle elastic fiber system were investigated in the diaphragm and rectus abdominis muscles of 1-, 4-, 8- and 18-month-old rats. The activation patterns of these muscles differ in that the diaphragm is regularly mobilized tens of times every minute during the entire life of the animal whereas the rectus abdominis, although mobilized in respiration, is much less and more irregularly activated. The elastic fibers were stained by the Verhoeff technique for mature elastic fibers. Weigert stain was used to stain mature and elaunin elastic fibers, and Weigert-oxone to stain mature, elaunin and oxytalan elastic fibers. The density of mature and elaunin elastic fibers showed a progressive increase with age, whereas the amount of oxytalan elastic fibers decreased in both diaphragm and rectus abdominis muscles and their muscular fasciae. These age-related quantitative and structural changes of the elastic fiber system may reduce the viscoelastic properties of the diaphragm and rectus abdominis muscles, which may compromise the transmission of tensile muscle strength to the tendons and may affect maximum total strength. (+info)
Quantification of the differences in electromyographic activity magnitude between the upper and lower portions of the rectus abdominis muscle during selected trunk exercises.
BACKGROUND AND PURPOSE: Controversy exists around exercises and clinical tests that attempt to differentially activate the upper or lower portions of the rectus abdominis muscle. The purpose of this study was to assess the activation of the upper and lower portions of the rectus abdominis muscle during a variety of abdominal muscle contractions. SUBJECTS: Subjects (N = 11) were selected from a university population for athletic ability and low subcutaneous fat to optimize electromyographic (EMG) signal collection. METHODS: Controlling for spine curvature, range of motion, and posture (and, therefore, muscle length), EMG activity of the external oblique muscle and upper and lower portions of rectus abdominis muscle was measured during the isometric portion of curl-ups, abdominal muscle lifts, leg raises, and restricted or attempted leg raises and curl-ups. A one-way repeated-measures analysis of variance was used to test for differences in activity between exercises in the external oblique and rectus abdominis muscles as well as between the portions of the rectus abdominis muscle. RESULTS: No differences in muscle activity were found between the upper and lower portions of the rectus abdominis muscle within and between exercises. External oblique muscle activity, however, showed differences between exercises. DISCUSSION AND CONCLUSION: Normalizing the EMG signal led the authors to believe that the differences between the portions of the rectus abdominis muscle are small and may lack clinical or therapeutic relevance. (+info)
The extracellular space of voluntary muscle tissues.
The volume occupied by the extracellular space has been investigated in six types of voluntary muscles: sartorius (frog), semitendinosus (frog), tibialis anticus longus (frog), iliofibularis (frog), rectus abdominis (frog), and diaphragm (rat). With the aid of four types of probe material, three of which are conventionally employed (inulin, sorbitol, sucrose) and one of which is newly introduced (poly-L-glutamate), and a different experimental method, we have demonstrated that the "true" extracellular space of frog sartorius, semitendinosus, tibialis anticus longus, and iliofibularis muscle and of rat diaphragm muscle is equal to, or probably less than, 8-9% (v/w) of the tissue. The frog rectus muscle shows a somewhat higher ceiling value of 14%. (+info)
Neurochemical phenotypes of MRF neurons influencing diaphragm and rectus abdominis activity.
In prior studies that used transneuronal transport of isogenic recombinants of pseudorabies virus, we established that medial medullary reticular formation (MRF) neurons sent collateralized projections to both diaphragm and abdominal muscle motoneurons. Furthermore, inactivation of MRF neurons in cats and ferrets increased the excitability of diaphragm and abdominal motoneurons, suggesting that MRF neurons controlling respiratory activity are inhibitory. To test this hypothesis, the present study determined the neurochemical phenotypes of MRF premotor respiratory neurons in the ferret by using immunohistochemical procedures. Dual-labeling immunohistochemistry combining pseudorabies virus injections into respiratory muscles with the detection of glutamic acid decarboxylase-like immunoreactive and glutamate-like immunoreactive cells showed that both GABAergic and glutamatergic MRF neurons project to respiratory motoneurons, although the latter are more common. These data suggest that the role of the MRF in respiratory regulation is multifaceted, as this region provides both inhibitory and excitatory influences on motoneuron activity. (+info)