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PubMed1987

On the role, inactivation and origin of endogenous adenosine at the frog neuromuscular junction.

1. The effects of adenosine deaminase, inosine, alkylxanthines (8-phenyltheophylline (8-PT), theophylline and isobutylmethylxanthine (IBMX], dipyridamole, alpha, beta-methylene ADP (AOPCP) and ATP analogues (alpha, beta-methylene ATP and beta, gamma-methylene ATP) on evoked end-plate potentials (e.p.p.s) were investigated in innervated sartorius muscles of the frog, in which twitches had been prevented with tubocurarine. The effects of 8-PT and IBMX on the amplitude and quantal content of e.p.p.s were also investigated in innervated sartorius muscles of the frog, in which twitches had been prevented with high-magnesium solutions. 2. Adenosine deaminase reversibly increased the amplitude of e.p.p.s and prevented the reduction caused by exogenously applied adenosine on e.p.p. amplitude. The increase caused by adenosine deaminase was equivalent to the decrease caused by 12 +/- 5.8 microM-adenosine on e.p.p. amplitude. 3. Inosine, the product of adenosine deamination, was virtually devoid of effect on e.p.p.s. 4. The adenosine receptor antagonists at the frog neuromuscular junction, 8-PT and theophylline, increased in a concentration-dependent manner the amplitude of e.p.p.s in the presence of tubocurarine. 8-PT increased the amplitude and quantal content of e.p.p.s in the presence of high magnesium. IBMX, which does not behave as an adenosine receptor antagonist at the frog neuromuscular junction, decreased the amplitude of e.p.p.s in the presence of tubocurarine or high-magnesium solutions. 5. Dipyridamole, an adenosine uptake blocker, decreased the amplitude of e.p.p.s, and in a concentration that did not affect neuromuscular transmission potentiated the depressing effect of adenosine, but not that of 2-chloroadenosine, on the amplitude of e.p.p.s. 6. AOPCP, an inhibitor of 5'-nucleotidase, increased the amplitude of e.p.p.s and markedly attenuated the depressing effect of ATP, but not that of adenosine, on e.p.p. amplitude. 7. The ATP analogue, alpha, beta-methylene ATP, which is not a substrate for 5'-nucleotidase, was virtually devoid of effect on e.p.p.s. beta, gamma-Methylene ATP, which can be a substrate for 5'-nucleotidase, mimicked the depressing effect of ATP on e.p.p. amplitude, an effect which was also reduced by AOPCP. 8. It is concluded that in conditions in which the initial quantal content is assumed to be normal (1) endogenous adenosine depresses neuromuscular transmission, (2) at the neuromuscular junction adenosine is inactivated through a dipyridamole-sensitive uptake process, and (3) released adenine nucleotides might contribute to the pool of endogenous adenosine which modulates neuromuscular transmission.

5'-Nucleotidase↗

PubMed1990

Idiopathic meralgia paresthetica.

Idiopathic meralgia paresthetica was treated surgically in 14 men and 11 women, the latter group were a decade older on average. Treatment was unsatisfactory if symptoms had been present for longer than 18 months. Reexploration of the nerve was not therapeutic in those cases in which the initial decompression provided no relief. The usual course of the lateral femoral cutaneous nerve is deep to the lateral end of the inguinal ligament but superficial to the sartorius muscle. However, the nerve may overlie the anterior iliac wing or pass between two slips of the inguinal ligament and may also be compressed if it passes deep to or through the sartorius muscle.

Adult↗

PubMed1991

Extracellular metabolism of adenine nucleotides and adenosine in the innervated skeletal muscle of the frog.

The effects of coformycin, alpha,beta-methylene ADP, dipyridamole in the absence and presence of erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), nitrobenzylthioinosine (NBTI), mioflazine and ouabain on the metabolic pathways of exogenously applied ATP and its metabolites in the frog innervated sartorius muscle were investigated. ATP catabolism yielded ADP, AMP, IMP, adenosine and inosine; the ecto-ATPase in situ was shown to be Ca(2+)- or Mg(2+)-activated with a Kmapp for ATP of 767 +/- 48 microM. AMP catabolism yielded IMP, adenosine and inosine; inosine was formed from either exogenous IMP or exogenous adenosine. Catabolism of AMP into IMP was blocked by coformycin, which enhanced adenosine and inosine formation from AMP. alpha,beta-Methylene ADP blocked adenosine formation from AMP and inosine formation from IMP; formation of IMP from AMP was enhanced by alpha,beta-methylene ADP. Complete blockade of AMP degradation was achieved with the simultaneous use of coformycin and alpha,beta-methylene ADP. Dipyridamole attenuated but did not completely block extracellular adenosine removal and inosine appearance in the bath. EHNA, applied in the presence of dipyridamole, did not cause any further attenuation of extracellular adenosine removal. Mioflazine, NBTI and ouabain did not affect adenosine disappearance from the bath. The results suggest that, in the frog innervated sartorius muscle, ATP can be sequentially catabolized into AMP which is then catabolized either into IMP or into adenosine. This extracellular degradation of AMP into IMP might then constitute a shunt-like mechanism to control the levels of adenosine formed from adenine nucleotides.

Adenine↗

PubMed1973

Action of adenosine triphosphate on endplate potentials recorded from muscle fibres of the rat-diaphragm and frog sartorius.

Evoked and spontaneous endplate potentials (e.p.ps) were recorded with intracellular electrodes from fibres of the rat diaphragm and the frog sartorius muscle. The amplitudes of the evoked e.p.ps were reduced to about one-half their control values in the presence of 0.1 mm and 0.2 mm of adenosine triphosphate (ATP). The amplitude of the spontaneous endplate potentials (miniature e.p.ps) was unaffected by ATP but their frequency was reduced.

Adenosine Triphosphate↗

PubMed2000

The effect of nicotinamide on spontaneous and induced activity in smooth and skeletal muscle.

BACKGROUND AND PURPOSE: Nicotinamide (NA) is currently undergoing clinical trials as a tumour radiosensitizer. The dose that can be administered is currently 80 mg/kg per day, but this may be restricted to 60 mg/kg per day by the high incidence of nausea and vomiting. To investigate some of NA's underlying mechanisms of action, we have used an ex vivo system to study the direct effect of this drug, over a wide range of concentrations, on isolated spontaneously active rat ileum. Effects on the gut were compared with the action of NA on skeletal and vascular smooth muscle. MATERIALS AND METHODS: Isolated rat ileum rings were perfused with oxygenated Krebs' solution in an organ bath. NA (1 microM to 10 mM) was introduced to the perfusate and the change in amplitude of spontaneous peristaltic activity recorded. Dissected frog sartorius muscle was bathed in modified oxygenated Ringer's solution in an organ bath. The muscle was electrically stimulated to generate isometric contractions. Tension was then measured before and after the addition of a range of NA concentrations (8.2-24.6 mM) to the organ bath. RESULTS: NA inhibited peristalsis in the ileum in a dose-dependent manner. At a drug concentration of 1 mM the amplitude of contractions was reduced to <50% of the initial control value. NA had no effect on the electrically induced contractions in the isolated frog sartorius muscle. CONCLUSIONS: Gut smooth muscle is highly sensitive to the relaxant effect of NA producing 50% relaxation at a concentration approximately 10 fold lower than that required in rat arterial smooth muscle, while having no effect on non-mammalian skeletal smooth muscle. This may provide explanations for the occurrence of emesis in patients undergoing combined nicotinamide therapies and highlight possible alternatives available to counter this unwanted side-effect.

Animals↗

PubMed1986

Geographutoxin II, a novel peptide inhibitor of Na channels of skeletal muscles and autonomic nerves.

Geographutoxin II (GTX II, 3 X 10(-9) to 10(-7) M) from a cone shell Conus geographus inhibited twitch responses of the isolated mouse diaphragm to direct stimulation in a dose-dependent manner. The contraction of the diaphragm induced by grayanotoxin I or veratridine was abolished by GTX II (3 X 10(-7) M), whereas the contractile response to KCI or caffeine was not affected. GTX II induced similar effects on isolated bullfrog sartorius muscles, but required higher concentrations (6 X 10(-7) to 3 X 10(-6) M). GTX II (greater than 10(-6) M) inhibited or abolished the action potential evoked in sartorius muscles markedly. In the isolated guinea pig vas deferens and ileum, GTX II caused a dose-dependent inhibition of the twitch responses to indirect nerve stimulation at concentrations of 3 X 10(-8) to 10(-6) M and 10(-7) to 10(-6) M, respectively. But the toxin had no effect on the dose contractile-response curves for norepinephrine, carbamylcholine or KCI in the vas deferens and for carbamylcholine or histamine in the ileum. GTX II (5 X 10(-8) to 10(-6) M) decreased norepinephrine release induced by veratridine from the vas deferens in a dose-dependent manner. These results suggest that GTX II blocks the voltage-sensitive Na channels in the cell membrane of skeletal muscles and autonomic nerves and these may play an important role in the mechanism of inhibitory effects of GTX II on contractile responses of these tissues to electrical stimulation.

Amino Acid Sequence↗

PubMed1987

Neuropeptide Y-like immunoreactivity in bullfrog sympathetic ganglia is restricted to C cells.

Staining the entire chain of paravertebral sympathetic ganglia in the bullfrog with an antiserum against porcine neuropeptide Y (NPY) revealed that, in each ganglion, a subpopulation of neurons expresses NPY-like immunoreactivity. Chromaffin cells in the sympathetic ganglia and in the adrenal gland were not stained by the anti-NPY serum. Since neurons in ganglia 9 and 10 of the sympathetic chain can be classified into 3 distinct groups on the basis of established electrophysiological criteria, we sought to identify the neurons in these ganglia that contain the NPY-like immunoreactivity. Accordingly, a series of cells was impaled with intracellular recording electrodes, identified as either fast B-, slow B-, or C-type neurons, filled with Lucifer yellow, and then processed with the anti-NPY serum for indirect immunofluorescence. These double-label experiments revealed that NPY-like immunoreactivity is expressed selectively by C-type sympathetic neurons. Counts of immunoreactive cells indicate that 55% of the neurons in ganglia 9 and 10 are C cells. A major target of the C cells appears to be the vasculature. In 3 different tissues innervated by sympathetic neurons, namely, the adrenal gland, the sartorius muscle, and the skin of the hindlimb, axons containing NPY-like immunoreactivity were found primarily within or near blood vessels. Within 14-60 d after extirpation of sympathetic ganglia 9 and 10, most immunoreactive axons in the sartorius muscle and nearby skin disappeared. In conjunction with other evidence, the possibility arises that sympathetic C cells function as vasomotor neurons that use an NPY-like substance and epinephrine as cotransmitters.

Animals↗

PubMed1984

Occurrence of the "capillary contractility" phenomenon and its significance in the distribution of microvascular flow in frog skeletal muscle.

The phenomenon of "capillary contractility" was first described more than 100 years ago. Recent reports on this phenomenon in the frog mesentery have been based on the observation of dramatic reductions of luminal diameter and blood flow during electrical stimulation of the capillary wall. The aim of this study was to establish the presence and the occurrence of this phenomenon in the frog sartorius muscle and to evaluate its contribution to the distribution of flow. Eight 1.3 X 1.7-mm areas of the muscle surface in eight anesthetized frogs were visualized by means of a microscope and also video-recorded during stimulation experiments. Microelectrodes and semitransparent surface electrodes introduced constant currents (0.1 to 1.0 microA) or pulse trains (5-msec pulse width, 1 to 64 Hz frequency, -0.2 to -5.4 V amplitude) either to individual capillaries or to whole populations of capillaries situated in these areas. Caution was exercised that stimuli did not cause muscle twitching. Red cell velocity in capillaries was measured from video recordings by the flying spot technique. Microelectrode stimulations caused flow stoppages in 4 out of 60 individual stimulated capillaries. Surface electrode stimulations had practically no effect on the mean red cell velocity in any of these populations but an appreciable effect on individual velocities in 7.5% of all capillaries in these populations. It is concluded that the phenomenon of electrically induced reductions of flow exists in the frog sartorius muscle, but it is scarce. It seems unlikely, therefore, that it represents a major mechanism of flow distribution in this tissue.

Acetylcholine↗

PubMed1977

Contraction and recovery of living muscles studies by 31P nuclear magnetic resonance.

1. Phosphorus nuclear magnetic resonance ((31)P NMR) can be used to measure the concentrations of phosphorus-containing metabolites within living tissue. We have developed methods for maintaining muscles in physiological condition, stimulating them and recording tension while at the same time accumulating their (31)P NMR spectra. Experiments were performed on frog sartorii and frog and toad gastrocnemii at 4 degrees C.2. The NMR signals from (31)P (the naturally occurring phosphorus) is weak, and signal averaging is required. In order to follow the time course of reactions it is necessary to maintain the muscles in a steady state for many hours while they are undergoing repeated contractions. Signals were accumulated in separate computer bins according to time after initiation of contraction. By these means spectra were obtained which corresponded to the different intervals during the contraction and recovery cycle.3. In the absence of stimulation, the spectra of frog sartorius muscles and of their extracts indicated concentrations of adenosine triphosphate (ATP), phosphoryl creatine (PCr), inorganic orthophosphate (P(i)) and sugar phosphates (sugar P) which are in reasonable agreement with the values obtained by chemical analysis.4. We have confirmed that unidentified resonances representing unknown compounds appear in the spectra of both frog and toad muscle; one of these is much larger in spectra from toad than from frog. We have found an additional small, unidentified resonance which appears to be specific to toad muscle.5. Spectra accumulated during actual contractions (1 s tetani every 2 min) did not differ dramatically from those accumulated throughout the 2 min cycle of contraction and partial recovery.6. Following 25 s tetanii, approximately 20% of the PCr had been hydrolysed; it was then rebuilt exponentially with a half-time of about 10 min. The increase in [P(i)] immediately after contraction and the time course of its disappearance corresponded to the changes in [PCr]. During the later half of the recovery period the concentration of P(i) was reduced to below that in resting muscle. The [sugar P] remained very high ( approximately 4 mmol kg(-1)) throughout the 56 min interval between contractions.7. When frog sartorii were tetanized for 1 s every 2 min, the changes in [PCr] and [P(i)] between contractions could not be observed because too little signal was obtained from these small muscles. However, when toad gastrocnemii were similarly stimulated, the changes in these compounds could be readily detected and were even greater than expected.8. The position of the P(i) resonance can be used to monitor intracellular pH and changes in pH. Under the conditions of our experiments the average intracellular pH in unstimulated frog sartorius muscles was 7.5. After a 25 s tetanus this was observed to move in the acid direction by a few tenths of a pH unit and to return to its pre-stimulation value before the end of the recovery period. After a 1 s contraction of toad gastrocnemius the environment of P(i) became slightly more alkaline for the first few seconds.

Adenosine Triphosphate↗

PubMed2000

Effects of feeding on metabolism, gas transport, and acid-base balance in the bullfrog Rana catesbeiana.

Massive feeding in ectothermic vertebrates causes changes in metabolism and acid-base and respiratory parameters. Most investigations have focused on only one aspect of these complex changes, and different species have been used, making comparison among studies difficult. The purpose of the present study was, therefore, to provide an integrative study of the multiple physiological changes taking place after feeding. Bullfrogs (Rana catesbeiana) partly submerged in water were fed meals (mice or rats) amounting to approximately (1)/(10) of their body weight. Oxygen consumption increased and peaked at a value three times the predigestive level 72-96 h after feeding. Arterial PO(2) decreased slightly during digestion, whereas hemoglobin-bound oxygen saturation was unaffected. Yet, arterial blood oxygen content was pronouncedly elevated because of a 60% increase in hematocrit, which appeared mediated via release of red blood cells from the spleen. Gastric acid secretion was associated with a 60% increase in plasma HCO3(-) concentration ([HCO3(-)]) 48 h after feeding. Arterial pH only increased from 7.86 to 7.94, because the metabolic alkalosis was countered by an increase in PCO(2) from 10.8 to 13.7 mm Hg. Feeding also induced a small intracellular alkalosis in the sartorius muscle. Arterial pH and HCO3(-) returned to control values 96-120 h after feeding. There was no sign of anaerobic energy production during digestion as plasma and tissue lactate levels remained low and intracellular ATP concentration stayed high. However, phosphocreatine was reduced in the sartorius muscle and ventricle 48 h after feeding.

Acid-Base Equilibrium↗

PubMed1991

Influence of dietary flaxseed oil on the performance, muscle protein deposition, and fatty acid composition of broiler chicks.

Experiments were conducted to assess the effect of feeding flaxseed oil on the performance, muscle protein deposition, and fatty acid composition of broiler chicks. Four levels of dietary flaxseed oil were fed in combination with animal tallow to give a total of 6% added fat in the diets. The diets were isonitrogenous and isocaloric. Mortality, weight gain, feed consumption, and feed efficiency were not significantly different among treatments. Dietary treatments had no significant effects on the relative weights of the Extensor digitorum communis and Sartorius muscles nor on their protein or lipid contents. Feeding flaxseed oil resulted in increased accumulation of omega 3 fatty acids in skeletal muscle lipids. Increased amounts of desaturation and elongation products (C20:3, C20:5, C22:5, and C22:6) of alpha-linolenate (C18:3 omega 3) were observed in the Sartorius muscle lipids of chicks fed flaxseed oil. Amounts of these omega 3 fatty acids increased with duration of feeding. The amounts of omega 6 fatty acids (C20:2, C20:3, C20:4) were significantly depressed in muscle lipids after 21 days of feeding flaxseed oil. The effects of flaxseed oil on tissue amounts of individual saturated fatty acids were minimal, but amounts of monounsaturated fatty acids, especially C18:1, were depressed.

Animals↗

PubMed1997

Abdominal and hip flexor muscle activation during various training exercises.

The purpose of this study was to provide objective information on the involvement of different abdominal and hip flexor muscles during various types of common training exercises used in rehabilitation and sport. Six healthy male subjects performed altogether 38 different static and dynamic training exercises trunk and hip flexion sit-ups, with various combinations of leg position and support, and bi- and unilateral leg lifts. Myoelectric activity was recorded with surface electrodes from the rectus abdominis, obliquus externus, obliquus internus, rectus femoris, and sartorius muscles and with indwelling fine-wire electrodes from the iliacus muscle. The mean electromyogram amplitude, normalised to the highest observed value, was compared between static and dynamic exercises separately. The hip flexors were highly activated only in exercises involving hip flexion, either lifting the whole upper body or the legs. In contrast, the abdominal muscles showed marked activation both during trunk and hip flexion sit-ups. In hip flexion sit-ups, flexed and supported legs increased hip flexor activation, whereas such modifications did not generally alter the activation level of the abdominals. Bilateral, but not unilateral, leg lifts required activation of abdominal muscles. In trunk flexion sit-ups an increased activation of the abdominal muscles was observed with increased flexion angle, whereas the opposite was true for hip flexion sit-ups. Bilateral leg lifts resulted in higher activity levels than hip flexion sit-ups for the iliacus and sartorius muscles, while the opposite was true for rectus femoris muscles. These data could serve as a basis for improving the design and specificity of test and training exercises.

Abdominal Muscles↗

PubMed1989

Effects of dietary beef and soy protein on tissue composition and low density lipoprotein uptake in young pigs.

To study effects of dietary protein source on plasma cholesterol homeostasis, six littermate pairs of 8-wk-old, castrated male pigs were assigned randomly to high fat diets containing either lean beef or soy protein isolate, with beef tallow as the major fat source in both diets. Diets were fed for 6 wk, with blood samples taken weekly and analyzed for lipid composition. At 6 wk, each pig was injected with [3H]cholesterol- and [14C]sucrose-labeled low density lipoproteins, and serial blood samples were taken. Pigs were then killed, and several tissues were sampled. Results show that dietary beef or soy protein, when fed with beef tallow as a fat source, has differential effects on rates of uptake of intact LDL by heart, M. sartorius muscle and subcutaneous adipose tissue, and on rates of uptake of LDL cholesterol by net free cholesterol exchange in subcutaneous and perirenal adipose tissues. Dietary protein source affected the composition of only two tissues analyzed. Pigs fed the beef-based diet had greater lipid concentrations in M. sartorius muscle, whereas pigs fed the soy protein-based diet had greater lipid concentrations in heart. Source of dietary protein did not influence in vivo kinetics of LDL cholesterol removal from blood plasma.

Animals↗

PubMed1978

Sensitivity of excitable and inexcitable membranes to alpha-dihydrograyanotoxin II.

A variety of excitable and inexcitable preparations have been examined for their sensitivity to the depolarizing action of alpha-dihydrograyanotoxin II. alpha-Dihydrograyanotoxin II was effective in producing membrane depolarization in giant axons from the crayfish (Procambarus clarki) and sartorius muscle fibers from the frog (Rana pipiens) and the salamander (Taricha torosa). The toxin-induced depolarization was reversed by lowering the external sodium concentration. High concentrations of tetrodotoxin and saxitoxin were also effective in reversing the depolarization in the various grayanotoxin-sensitive preparations studied except in the salamander sartorius muscle, in which sodium-dependent action potentials were highly resistant to tetrodotoxin and saxitoxin. In contrast, alpha-dihydrograyanotoxin II was ineffective in changing the resting membrane potential in the muscle fibers of the crayfish (Procambarus clarki and Orconectes virilis) and in the salivary gland giant cells from Drosophila virilis. Of the preparations that were examined, only the membranes that produce a sodium-dependent action potential are sensitive to the depolarizing action of alpha-dihydrograyanotoxin II.

Action Potentials↗

PubMed1997

[Treatment strategy in inguinal injection abscess and complications].

From 1994 to March 1997, 12 patients with 15 drug-related abscesses of the groin were treated at the Surgical Department of Lübeck Medical University. Besides laboratory, serological and microbiological examinations, the standard diagnostic investigation consisted of sonography or duplex sonography. If indicated, the diagnosis was extended to include, for example, clarification of the retroperitoneum by CT. The most common accompanying disease was deep femoral vein thrombosis. Substitution was planned individually. After surgical débridement and perioperative administration of a beta-lactam-protected acylaminopenicillin, open wound treatment was successfully carried out in 13 cases; secondary closure was performed four times in cases of good compliance. One abscess led to necrotising of the femoral artery; saphenous vein was interposed because of erosion bleeding and formation of aneurysm. In a second case, the bifurcation was reconstructed with saphenous vein after external resection of an infected false aneurysm and early occlusion. Both defects were covered by rotation of sartorius muscle and mesh graft. On the basis of the treatment concept, a rapid and successful intervention was possible; complications such as sepsis, amputation or withdrawal delirium did not occur. Resistance against the antibiotic was not observed. In the case of infected aneurysm, we prefer the autogenous saphenous vein graft followed by rotation of sartorius muscle and mesh graft. Ligation or excision leads to high rates of claudication or amputation; extended reconstructions are threatened by insufficient compliance of the patients; the use of synthetic grafts is endangered by further bacteraemia or infections.

Abscess↗

PubMed1977

Effect of denervation on the permeability of acetylcholine-activated channels to organic cations.

Experiments were perfomed on chronically denervated frog sartorius muscles to determine the permeability of the acetylcholine-activated channels to organic cations. The membrane voltage response to bath-applied acetylcholine was measured with the moving electrode when the muscles were bathed in normal Ringer and in Ringer in which all of the Na+ had been replaced with an organic cation. The magnitude of the maximum voltage response was used to estimate the permeability of the channel to the organic cation. These results were compared with those which have been reported for innervated frog sartorius muscles (Maeno, Edwards, and Anraku, 1977). It is concluded that the permeability to a wide range of organic cations is virtually identical for the extrajunctional channels which develop following denervation and the channels with are localized at the junctional region of innervated muscles.

Acetylcholine↗

PubMed1989

Cellular responses to Pyrularia thionin are mediated by Ca2+ influx and phospholipase A2 activation and are inhibited by thionin tyrosine iodination.

Pyrularia thionin, isolated from nuts of Pyrularia pubera, is a strongly basic peptide of 47 amino acids. The amino acid sequence and configuration of its four disulfide bonds place this plant peptide, known to be hemolytic, cytotoxic, and neurotoxic, among the thionins. We report and compare several cellular responses mediated by Pyrularia thionin: hemolysis of human erythrocytes, activation of an endogenous phospholipase A2 in Swiss 3T3 cells, cytotoxicity toward HeLa and mouse B16 melanoma cells in culture, viability of rat hepatocytes and lymphocytes measured by trypan blue exclusion, and lethality in mice. Cellular responses related to ion movement include a toxin-mediated influx of Ca2+ into mouse P388 cells measured by Fura-2 fluorescence, depolarization of mouse P388 plasma membrane measured by fluorescence of bis(1,3-diethylthiobarbituric acid)trimethine oxonol (bisoxonol), and depolarization of frog (Rana pipiens) sartorius muscle determined by direct measurement of membrane potential. Graded iodination of Pyrularia thionin leads to a related loss of activity for hemolysis, phospholipase A2 activation, cytotoxicity, and lethality in mice. The mediated Ca2+ influx into and depolarization of P388 cells require Ca2+ in the external medium and are inhibited by 100 microM Ni2+. Depolarization of sartorius muscle by Pyrularia thionin also requires a functional Ca2+ channel, as shown by verapamil inhibition. This muscle depolarization also involves phospholipase A2 activation because dexamethasone and quinacrin, but not indomethacin, protect against depolarization. The IC50 values for viability of rat hepatocytes and splenic lymphocytes measured by trypan blue exclusion were 0.17 and 40 microM, respectively. The general response of cells to Pyrularia thionin involves a membrane alteration leading to depolarization and a channel-mediated influx of Ca2+. There is a related activation of phospholipase A2 that results in loss of membrane integrity, hemolysis in the case of erythrocytes, and eventually cell death. Iodination of Pyrularia thionin leads to a corresponding inhibition of all three cellular responses, which indicates an essential role for tyrosine in either maintenance of peptide structure or interaction of the peptide with cellular membranes.

Animals↗

PubMed1998

Free groin flap for reconstruction of the tongue and oral floor.

The authors report the use of free groin flaps to close intraoral defects in 24 patients following ablative tongue cancer surgery. The lateral thin portion of the flap was used for tongue reconstruction, and the deepithelialized medial thick portion for filling the mandibular defect and for covering the important vessels in the neck. In lean patients, if the medial deepithelialized portion was too thin for adequate coverage, the proximal sartorius muscle was included to prevent postoperative orocervical fistula. The advantages of the groin flap in reconstructing the tongue and oral floor after hemiglossectomy include the following: (1) a suitable amount of tissue is available for both the tongue and oral floor; (2) the important vessels in the neck may be protected with the flap; (3) the proximal sartorius muscle can be included with the flap, if necessary; (4) donor-site morbidity is less than with other flaps; and (5) flap elevation can be done concurrently with the hemiglossectomy and radical neck dissection.

Adult↗