BLTR mediates leukotriene B(4)-induced chemotaxis and adhesion and plays a dominant role in eosinophil accumulation in a murine model of peritonitis

Leukotriene B(4) (LTB(4)) is a potent chemoattractant active on multiple leukocytes, including neutrophils, macrophages, and eosinophils, and is implicated in the pathogenesis of a variety of inflammatory processes. A seven transmembrane-spanning, G protein-coupled receptor, called BLTR (LTB(4) receptor), has recently been identified as an LTB(4) receptor. To determine if BLTR is the sole receptor mediating LTB(4)-induced leukocyte activation and to determine the role of LTB(4) and BLTR in regulating leukocyte function in inflammation in vivo, we generated a BLTR-deficient mouse by targeted gene disruption. This mouse reveals that BLTR alone is responsible for LTB(4)-mediated leukocyte calcium flux, chemotaxis, and firm adhesion to endothelium in vivo. Furthermore, despite the apparent functional redundancy with other chemoattractant-receptor pairs in vitro, LTB(4) and BLTR play an important role in the recruitment and/or retention of leukocytes, particularly eosinophils, to the inflamed peritoneum in vivo. These studies demonstrate that BLTR is the key receptor that mediates LTB(4)-induced leukocyte activation and establishes a model to decipher the functional roles of BLTR and LTB(4) in vivo.

Limb congestion enhances the synchronization of sympathetic outflow with muscle contraction

In this report, we examined if the synchronization of muscle sympathetic nerve activity (MSNA) with muscle contraction is enhanced by limb congestion. To explore this relationship, we applied signal-averaging techniques to the MSNA signal obtained during short bouts of forearm contraction (2-s contraction/3-s rest cycle) at 40% maximal voluntary contraction for 5 min. We performed this analysis before and after forearm venous congestion; an intervention that augments the autonomic response to sustained static muscle contractions via a local effect on muscle afferents. There was an increased percentage of the MSNA noted during second 2 of the 5-s contraction/rest cycles. The percentage of total MSNA seen during this particular second increased from minute 1 to 5 of contraction and was increased further by limb congestion (control minute 1 = 25.6 +/- 2.0%, minute 5 = 32.8 +/- 2.2%; limb congestion minute 1 = 29.3 +/- 2.1%, minute 5 = 37.8 +/- 3.9%; exercise main effect <0.005; limb congestion main effect P = 0.054). These changes in the distribution of signal-averaged MSNA were seen despite the fact that the mean number of sympathetic discharges did not increase over baseline. We conclude that synchronization of contraction and MSNA is seen during short repetitive bouts of handgrip. The sensitizing effect of contraction time and limb congestion are apparently due to feedback from muscle afferents within the exercising muscle.

Characterisation of human soft palate muscles with respect to fibre types, myosins and capillary supply

Four human soft palate muscles, and palatopharyngeus, the uvula, the levator and tensor veli palatini were examined using enzyme-histochemical, immunohistochemical and biochemical methods and compared with human limb and facial muscles. Our results showed that each palate muscle had a distinct morphological identity and that they generally shared more similarities with facial than limb muscles. The palatopharyngeus and uvula muscles contained 2 of the highest proportions of type II fibres ever reported for human muscles. In contrast, the levator and tensor veli palatini muscles contained predominantly type I fibres. A fetal myosin heavy chain isoform (MyHC), not usually found in normal adult limb muscles, was present in a small number of fibres in all palate muscles. The mean muscle fibre diameter was smaller than in limb muscles and the individual and intramuscular variability in diameter and shape was considerable. All palate muscles had a high capillary density and an unusually high mitochondrial enzyme activity in the type II fibres, in comparison with limb muscles. No ordinary muscle spindles were observed. The fibre type and MyHC composition indicate that the palatopharyngeus and uvula muscles are functionally involved in quick movements whereas the levator and tensor veli palatini muscles perform slower and more continuous contractions. The high aerobic capacity and the rich capillarisation suggest that the palate muscles are relatively fatigue resistant. Absence of ordinary muscle spindles indicates a special proprioceptive control system. The special morphology of the palate muscles may be partly related to the unique anatomy with only one skeletal insertion, a feature consistent with muscle work at low load and tension and which may influence the cytoarchitecture of these muscles. Other important factors determining the special morphological characteristics might be specific functional requirements, distinct embryological origin and phylogenetic factors.

Circulatory adjustments of voluntary muscle in anemia

Simultaneous measurements of the blood flow through the human forearm and of the arteriovenous oxygen difference of forearm blood have shown that in moderate anemia the need for oxygen was met by an increase in the arteriovenous oxygen difference without increase in blood flow. When the hemoglobin fell below 4 gm.% the blood flow rose. In subjects in whom the blood flow had increased, the venous oxygen saturation was below 15%. Cardiac output has been shown to increase when the hemoglobin falls below 8 gm.%. It is concluded that the initial increase in heart output is not due to ischemia of voluntary muscle but is required for maintaining the metabolism of the brain and the heart itself.

Submitted on July 3, 1958

Total capillary bed in striated muscles of guinea pigs native to the Peruvian mountains

The total capillary bed in skeletal muscle of guinea pigs has been determined by perfusion with India ink and counting capillaries in cross sections of gelatin embedded muscle. Comparative studies have indicated the importance of age, the muscle studied and the site where counts were performed. Capillaries were more evently distributed in the red than the white areas of the muscle. Free exercise or restriction in cages during the life span did not materially effect the results, although in cross sections some gross enlargement of the red areas was observed in the free exercise group. A significantly greater number of capillaries per square millimeter of muscle tissue were observed in the red area of muscles from animals native to the Peruvian mountains. The red area of these muscles was also more extensive than in the sea level born controls. The possible adaptive significance of these characteristics has been indicated.

Spontaneous leukocyte rolling in rat and mouse microvessels is independent of mast cell activity

OBJECTIVE AND DESIGN

The role of mast cells in spontaneous leukocyte rolling in venules of the mouse cremaster muscle and rat mesentery was investigated.

MATERIALS

The experiments were carried out using mast cell-deficient rats (Ws/Ws), WBB6F1 mice (W/Wv), and their congenic littermates (wild type).

TREATMENT

Administration of compound 48/80 intraperitoneally (50 microg) in rats and intrascrotally (5 microg) in mice, 4 h prior to the experiments.

METHODS

Intravital microscopy of the terminal vascular beds in mouse cremaster muscle and rat mesentery.

RESULTS

The level of spontaneous leukocyte rolling and the rolling velocity in venules of mast cell-deficient animals exactly matched that seen in wild-type animals. Challenge with compound 48/80 markedly increased leukocyte adhesion and emigration in venules of wild-type animals. In contrast, the number of adherent and extravascular leukocytes was very low in compound 48/80-challenged animals lacking mast cells and did not differ from that seen in control animals treated with phosphate-buffered saline.

CONCLUSIONS

The presence or activation of mast cells has no bearing on spontaneous leukocyte rolling, at least not in rat and mouse microvessels.

The effect of isoprenaline on the blood flow through individual skeletal muscles in the anaesthetised cat

The effects of intra-arterially and intravenously administered isoprenaline on the venous outflow from individual skeletal muscles in the hind limbs of cats under chloralose anaesthesia were studied. By intraarterial injection isoprenaline was more powerful in causing vasodilatation than adrenaline. The dilator response to intravenously administered isoprenaline was shown by cross-circulation techniques and by the use of a blood pressure stabiliser, to be reflexly inhibited by a vasoconstriction initiated by the fall in blood pressure. In the innervated muscle when vasomotor tone was high, intravenously administered adrenaline was more potent than isoprenaline in producing vasodilatation. The reverse was true in the acutely denervated muscle. The dilator response to isoprenaline was shown to be the result of a direct action on the muscle blood vessels; no evidence was obtained of a reflex dilatation, such as has been demonstrated with adrenaline and noradrenaline.

Reduced muscle vascular resistance in intrauterine growth restricted newborn piglets

It has been shown that asymmetrical intrauterine growth restriction is denoted by disproportional reduction of muscle mass compared to body weight reduction. However, the effects of IUGR on regional vascular resistance and blood flow of skeletal muscles and their contractile function have not been studied until now. Therefore, muscle blood flow (MBF) and isometric force output of serial stimulated hindlimb plantar flexors was measured in thiopental -anesthetized normal weight (NW; n = 9) and intrauterine growth restricted (IUGR; n = 9) one-day-old piglets. Additionally, muscle vascular resistance (MVR) and thyroid hormones were estimated. MBF was found to be markedly increased in IUGR piglets by 36% with a concomitant MVR reduction of 37% (p < 0.05). Isometric force of the plantar flexors was considerably higher in NW than in IUGR piglets (p < 0.05). However, amount of muscle fatigue was more pronounced in NW piglets (9.1+/-2.8%) than was in IUGR piglets (3.7+/-2.3%) (p < 0.05). Furthermore, specific tension of NW muscles (18.8+/-0.7 N/cm2) was significantly lower than for IUGR muscles (21.2+/-0.9 N/cm2) (P<0.05). IUGR newborn piglets exhibited increased plasma levels of thyroxine (T4) (p < 0.05), whereas triiodothyronine (T3) showed similar values in both animal groups. These data clearly indicate that muscle hemodynamics and contractile function are more developed in newborn IUGR piglets. Furthermore it is suggested that the improved tolerance to fatigue during isometric contractions may indicate an increased oxidative capacity of calf muscles due to intrauterine growth restriction.

Nitric oxide as a metabolic regulator during exercise: effects of training in health and disease

1. Accumulating animal and human data suggest that nitric oxide (NO) is important for both coronary and peripheral haemodynamic control and metabolic regulation during performance of exercise. 2. While still controversial, NO of endothelial origin is thought to potentiate exercise-induced hyperaemia, both in the peripheral and coronary circulations. The mechanism of release may include both acetylcholine derived from the neuromuscular junction and vascular shear stress. 3. A splice variant of neuronal nitric oxide synthase (NOS), nNOSmicro, incorporating an extra 34 amino acids, is expressed in human skeletal muscle. In addition to being a potential modulator of blood flow, skeletal muscle-derived NO is an important regulator of muscle contraction and metabolism. In particular, recent human data indicate that NO modulates muscle glucose uptake during exercise, independently of blood flow. 4. Exercise training in healthy individuals promotes adaptations in the various NO systems, which can increase NO bioavailability through a variety of mechanisms, including increased NOS enzyme expression and activity. Such adaptations likely contribute to increased exercise capacity and protection from cardiovascular events. 5. Cardiovascular risk factors, including hypercholesterolaemia, hypertension, diabetes and smoking, as well as established disease, are associated with impairment of the various NO systems. Given that NO is an important signalling mechanism during exercise, such impairment may contribute to limitations in exercise capacity through inadequate coronary or peripheral blood delivery and via metabolic effects. 6. Exercise training in individuals with elevated cardiovascular risk or established disease can increase NO bioavailability and may represent an important mechanism by which exercise training provides benefit in the setting of secondary prevention.

Carbon dioxide transport and carbonic anhydrase in blood and muscle

CO(2) produced within skeletal muscle has to leave the body finally via ventilation by the lung. To get there, CO(2) diffuses from the intracellular space into the convective transport medium blood with the two compartments, plasma and erythrocytes. Within the body, CO(2) is transported in three different forms: physically dissolved, as HCO(3)(-), or as carbamate. The relative contribution of these three forms to overall transport is changing along this elimination pathway. Thus the kinetics of the interchange have to be considered. Carbonic anhydrase accelerates the hydration/dehydration reaction between CO(2), HCO(3)(-), and H(+). In skeletal muscle, various isozymes of carbonic anhydrase are localized within erythrocytes but are also bound to the capillary wall, thus accessible to plasma; bound to the sarcolemma, thus producing catalytic activity within the interstitial space; and associated with the sarcoplasmic reticulum. In some fiber types, carbonic anhydrase is also present in the sarcoplasm. In exercising skeletal muscle, lactic acid contributes huge amounts of H(+) and by these affects the relative contribution of the three forms of CO(2). With a theoretical model, the complex interdependence of reactions and transport processes involved in CO(2) exchange was analyzed.

[Experimental study on selective thrombolytic activity of pro-urokinase]

OBJECTIVE

To evaluate the valve of pro-urokinase as a selective thrombolytic agent in microsurgery.

METHODS

The levators muscle model in rats was used to investigate the effect of pro-urokinase on dissolving ischemic thrombi and fibrinogenolytic activities in circulation by local infusion. The tissue microcirculation, pathologic appearance of rat lungs and muscles, and general fibrinogenolytic activities were observed.

RESULTS

The thrombolytic rate of pro-urokinase was 92.3% (P < 0.05), the positive rate of D-dime was 83.3%(P < 0.05). No significant change of alpha 2-PI was observed on general fibrinogenolytic activities(P > 0.05).

CONCLUSIONS

It is suggested that pro-urokinase can be used to dissolve the thrombi in microcirculation of free tissue transplantation without affect general fibrinogenolytic activities. It is safe to use pro-urokinase in free tissue transplantation.

[Power Doppler signals produced by static structures: a frequent cause of interpretation errors in the study of slow flows]

INTRODUCTION

The main characteristic of power Doppler US is its high sensitivity in showing blood vessels with small caliber and slow flow. However, artifacts are a common problem with this technique and they lead to impaired and subjective image reading. We analyzed the artifacts from Power Doppler signals from static structures both in vitro and in vivo.

MATERIAL AND METHODS

Some samples of different tissues (liver, muscle, fat) positioned into a water bath were studied with Power Doppler in vitro. The static structures were imaged with a 10 MHz transducer (Esaote AU4, Genoa, Italy) both through water and with the transducer resting directly on the tissue. PRF and WF were set differently every time and their individual/combined role in causing artifacts was assessed. Then we examined different organs in vivo to investigate if the same setting as in vitro would cause the same artifacts.

RESULTS

All our tissue samples exhibited strong and persistent color signals at low PRF and WF settings, with stronger signals at the solid/liquid interface and no signals from the liquid color box. Comparison of images acquired with same setting, particularly color gain, but different PRF (750 Hz to 3 KHz) or WF (50 to 600 Hz) showed that artifacts are mainly related to the latter. In vivo examinations showed similar findings, especially relative to the liquid/solid and solid hypoechoic/solid hyperechoic interfaces.

CONCLUSIONS

Persistent and fairly strong Power Doppler signals can be produced by echogenic structures with no flow; these artifacts are frequent at low PRF, but are mainly caused by incorrect WF setting. They are most frequent along interfaces with specular reflection. To conclude, we would like to stress that, in addition to motion artifacts, which are easier to recognize, other potentially misleading signals may come from static structures.

Diabetic muscle infarction

Diabetic muscle infarction is a rare complication of diabetes mellitus that is not clearly defined in the orthopaedic literature. This study is a descriptive case series of 7 new cases of diabetic muscle infarction and 55 previously reported cases in the literature. In the majority of patients, diabetic muscle infarction presents as a localized, exquisitely painful swelling and limited range of motion of the lower extremity. No cases affecting the muscles of the upper extremity have been observed. The onset is usually acute, persists for several weeks, and resolves spontaneously over several weeks to months without the need for intervention. Diabetic muscle infarction is a condition that should be considered in the differential diagnosis of any diabetic patient with lower extremity pain and swelling without systemic signs of infection. Magnetic resonance imaging is sensitive and specific enough to make the diagnosis. Muscle biopsy and surgical irrigation and debridement are not recommended since they are associated with complications. Pain management and activity restriction in the acute phase followed by gentle physical therapy is the treatment of choice. Recurrences in the same or opposite limb are common. Although the short-term prognosis is very good and the majority of cases resolve spontaneously, the long-term survival is uncertain in this patient population.

Modeling oxygen availability to exercising muscle

To quantify the role of factors determining O2 availability to exercising muscle, a model previously devised for the analysis of O2 uptake in lungs is used. With the variables: (1) blood flow (Q); (2) slope of the blood O2 equilibrium curve (betaO2); and (3) muscle blood-tissue O2 diffusing capacity (D(O2)), the extent of diffusion and perfusion limitations are determined by the 'equilibration index', Y(O2) = D(O2)/(Q x betaO2). Application to recent literature values on maximal O2 uptake in humans reveals diffusion limitation to be less important than perfusion limitation in normoxia, but to be predominant in deep hypoxia. The validity of the model is restricted by several factors whose disregard leads to an underestimation of muscle D(O2), i.e. an overestimation of diffusion limitation.

A model analysis of lactate accumulation during muscle ischemia

PURPOSE

The mechanistic basis of the relationship between tissue [O2] and tissue or blood lactate (LA) concentration during tissue hypoxia are not fully understood. However, blood and tissue lactate accumulation are still used as indicators of tissue hypoxia in critically ill patients. To investigate this relationship, we applied a previously developed mathematical model of human bioenergetics to simulate the integrated responses (cellular, tissue, and whole body) to moderate (10% to 45%) and severe (50% to 80%) reductions in muscle blood flow.

MATERIALS AND METHODS

Model simulations of muscle ischemia predicted metabolite concentration changes in muscle, splanchnic bed, and other tissues, and were compared with experimental data in humans for model validation.

RESULTS

In general, simulations closely predicted the pattern of change in substrates and control metabolites to that observed experimentally. Specifically, simulations showed that most of the increase in muscle LA production during moderate ischemia was due to an increase in pyruvate (PY) and notto the change in redox state induced by a small decrease in O2 consumption. However, during severe ischemia, changes in [LA]/[PY] ratio in venous blood corresponded very closely to changes in tissue redox state. Because both blood [LA] and [LA]/[PY] tracked changes in tissue redox state very well, these can be used reliably as indices of tissue hypoxia during severe muscle ischemia.

CONCLUSIONS

Based on the simulations, the commonly used threshold value for venous [LA]/[PY] = 14 as evidence of tissue hypoxia seems appropriate during severe ischemia.

Near-infrared spectroscopy: a potential method for continuous, transcutaneous monitoring for compartmental syndrome in critically injured patients

BACKGROUND

Near-infrared spectroscopy (NIRS) noninvasively measures tissue O2 saturation (StO2), and has been proposed as a means of monitoring for compartmental syndrome (CS). However, its specificity in hypoxemic, hypotensive patients with severely reduced systemic oxygen delivery has not been tested. We hypothesized that NIRS can differentiate muscle ischemia caused by shock from ischemia caused by CS.

METHODS

Nine swine were anesthetized and an NIRS probe placed over the anterolateral compartment of the hind leg. Compartment pressure was also measured. A nerve stimulator was placed over the peroneal nerve, and CS was defined as loss of dorsiflexion twitch. At 30-minute sequential intervals, mean arterial blood pressure was reduced to 60% of baseline (phlebotomy), fraction of inspired oxygen was reduced to 0.15, and compartment pressure was increased in one limb by interstitial albumin infusion until CS occurred.

RESULTS

Hypotension combined with hypoxemia reduced StO2 from 82+/-4% to 66+/-10%. CS further reduced StO2 to 16+/-12% (p<0.0001). During hypotension + hypoxemia + CS, control limb StO2 was 70+/-15% (p = 0.0002 vs. experimental limb).

CONCLUSION

NIRS detects muscle ischemia caused by CS despite severe hypotension and hypoxemia, making it potentially useful in critically injured, unstable patients.

[Muscle infarction. An unknown complication of diabetes mellitus]

INTRODUCTION

Diabetic muscle infarction (MI) is a rare and little-known complication of diabetes mellitus.

CASE REPORT

We report a case of relapsing MI in which magnetic resonance imaging (MRI) suggested the diagnosis. A 53-year-old man with multi-complicated type II diabetes mellitus was admitted to our unit for illness and deep tumefaction of the right thigh. Because of unconclusive MRI, a muscular biopsy of the lesion was performed and MI confirmed. Three months after, a left relapse of MI occurred. Immediate treatment with immobilization and heparinotherapy permitted a rapid recovery.

CONCLUSION

About 70 previously reported cases are reviewed. The mean age at presentation was about 40 years. MI was usually seen in patients with long-standing diabetes with multiple end organ microvascular complications. Homo- or heterolateral recurrences are reported in almost half of the patients. MRI is the best imaging technique for suggesting the diagnosis.

Arteriogenesis, the good and bad of it

Arteriogenesis, the process of collateral artery growth as an adaptation to major arterial occlusion, can be life- and tissue saving and may alter the natural course of the consequences and organ manifestations of arterial disease. This is achieved by an active growth process that is coupled to complete arterial remodeling with activation of proteases and destruction of the organ tissue in the immediate vicinity of the growing vessel, to create the space for a new artery which expands to about 20 times its original diameter. Much of the growth and remodeling is achieved by attraction, adhesion, activation and invasion of circulating cells, mostly monocytes, but also T-cells and basophiles. Growth factors that are already present, as well as those that are produced by invading cells, produce an environment of inflammation and facilitate coagulation and are therefore pro-atherogenic. It will be a challenge for future therapies with growth factors, chemokines and cytokines to neutralize the atherogenic and to maximize their arteriogenic properties.

Postexercise responses of muscle sympathetic nerve activity and blood flow to hyperinsulinemia in humans

Although insulin and exercise cause dramatic changes in physiological parameters, the impact of exercise on neural and hemodynamic responses to insulin administration has not been described. In a study of the effects of a single bout of exercise on blood pressure (BP), muscle sympathetic nerve activity (MSNA), and forearm blood flow (FBF) responses to insulin infusion during the postexercise period, 11 healthy men underwent, in a random order, two hyperinsulinemic euglycemic clamps performed after 45 min of 1) bicycle exercise (50% peak O(2) uptake, Exercise session) and 2) seated rest (Control session). Data were analyzed during baseline and steady-state periods. Although insulin levels and insulin sensitivity were similar, baseline plasma glucose levels were significantly lower in the Exercise than in the Control session. Mean BP was significantly lower (3%) and FBF was higher (27%) in the Exercise session. Exercise increased insulin-induced MSNA enhancement (84%) without changing FBF and BP responses to hyperinsulinemia. In conclusion, a single bout of exercise that does not alter insulin sensitivity exacerbates insulin-induced increase in MSNA without changing FBF and BP responses to hyperinsulinemia.

Muscle fiber characteristics in postmenopausal women with normal or impaired glucose tolerance

OBJECTIVE

Muscle fiber characteristics are altered in type 2 diabetes. We studied whether these alterations also exist in impaired glucose tolerance (IGT) and whether they are determinants of insulin sensitivity and glucose tolerance in postmenopausal women.

RESEARCH DESIGN AND METHODS

Percutaneous muscle biopsies from the vastus lateralis muscle were obtained from 77 postmenopausal women aged 57-59 years: 50 women with normal glucose tolerance (NGT) and 27 with IGT. The IGT group had a reduced insulin sensitivity compared with the NGT group (euglycemic-hyperinsulinemic clamp) (P = 0.003).

RESULTS

The groups did not differ in muscle fiber composition, as judged by the percentage of type I, IIa, or IIx fibers. In contrast, the IGT group had increased size of the IIa (mean +/-SD 3,776+/-987 vs. 3,078+/-862 microm2, P = 0.002) and IIx fibers (2,730+/-1,037 vs. 2,253+/-672 microm2, P = 0.017). There was a trend for the capillary diffusion areas (the muscle area supplied by each capillary) to be larger in the IGT group for the IIa (1,132+/-286 vs. 1,013+/-240 microm2, P = 0.061) and IIx fibers (1,020+/-246 vs. 906+/-240 microm2, P = 0.058). In the entire group, insulin sensitivity correlated with the size of the type IIa fibers (r = -0.28, P = 0.013), but not with the percentages of muscle fiber types. In a multiple regression, insulin sensitivity was determined by body fat content and HDL cholesterol level, while the size of the IIa fibers was not included in the model. Glucose tolerance was independently predicted by the number of capillaries/type I fiber, as well as by insulin sensitivity and triglyceride levels.

CONCLUSIONS

We conclude that although muscle fiber composition is not altered, women with IGT have larger type IIa and IIx muscle fibers and a trend for increased capillary diffusion areas for these fibers, compared with women with NGT. In the entire group, insulin sensitivity was determined mainly by body fat content, while muscle fiber capillarization may be of importance for glucose tolerance.

Gracilis muscle: arterial and neural basis for subdivision

The gracilis muscle is commonly utilized by reconstructive surgeons in a variety of applications as a pedicled muscle or musculocutaneous flap, and as a free tissue transfer for soft-tissue coverage or as a functioning muscle transfer. The muscle anatomy has been well documented in the past. The aim of the present study was to study comprehensively the intramuscular neurovascular anatomy as it relates to segmental neurovascular functioning muscle transfer. The study was carried out in a series of 14 human cadavers. Each cadaver was injected with a lead oxide, gelatin, and water solution through the femoral arteries (200 ml per kilogram). The overall length of the musculotendinous unit was 44 +/- 2 cm, and the tendon comprised up to 6 +/- 2 cm of the length. The main arterial supply to the muscle entered 10 +/- 1 cm from the attachment to the body and inferior ramus of the pubis (diameter, 1.5-2.5 mm). The distal portion of the muscle was supplied by one to three small arterial branches of the superficial femoral artery. Venous drainage was noted to be through paired venae comitantes. The motor nerve arises from the obturator nerve and enters the muscle in association with the major vascular pedicle. The nerve then splits within the muscle and runs longitudinally in two or three major branches within the muscle parallel to the arterial branches and muscle fibers. The neurovascular anatomy of the gracilis muscle was found to be remarkably consistent from specimen to specimen, varying only in the length of the muscle and tendon, and the number of minor pedicles supplying the distal portion of the muscle. This study confirms the suitability of the gracilis for segmental functional muscle transfer.

Past and current understanding of the pathophysiology of muscle cramps: why treatment of varicose veins does not relieve leg cramps

Historically relevant hypotheses on the pathophysiology of muscle cramps are reviewed. Psychosomatic, static, vascular, myogenic and neural theories are highlighted from a clinician's point of view. Modern neurophysiologic research leaves little doubt that muscle cramp is caused by excitation of spinal motor neurones mediated by changes in presynaptic input. Nevertheless, obsolete theories and relative treatments stubbornly persist in clinical practice.