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PubMed1994

Relaxation from rigor of skinned trabeculae of the guinea pig induced by laser photolysis of caged ATP.

The kinetics of ATP-induced rigor cross-bridge detachment were studied by initiating relaxation in chemically skinned trabeculae of the guinea pig heart using photolytic release of ATP in the absence of calcium ions (pCa > 8). The time course of the fall in tension exhibited either an initial plateau phase of variable duration with little change in tension or a rise in tension, followed by a decrease to relaxed levels. The in-phase component of tissue stiffness initially decreased. The rate then slowed near the end of the tension plateau, indicating transient cross-bridge rebinding, before falling to relaxed levels. Estimates of the apparent second-order rate constant for ATP-induced detachment of rigor cross-bridges based on the half-time for relaxation or on the half-time to the convergence of tension records to a common time course were similar at 3 x 10(3) M-1 s-1. Because the characteristics of the mechanical transients observed during relaxation from rigor were markedly similar to those reported from studies of rabbit psoas fibers in the presence of MgADP (Dantzig, J. A., M. G. Hibberd, D. R. Trentham, and Y. E. Goldman. 1991. Cross-bridge kinetics in the presence of MgADP investigated by photolysis of caged ATP in rabbit psoas muscle fibres. J. Physiol. 432:639-680), direct measurements of MgADP using [3H]ATP in cardiac tissue in rigor were made. Results indicated that during rigor, nearly 18% of the cross-bridges in skinned trabeculae had [3H]MgADP bound. Incubation of the tissue during rigor with apyrase, an enzyme with both ADPase and ATPase activity, reduced the level of [3H]MgADP to that measured following a 2-min chase in a solution containing 5 mM unlabeled MgATP. Apyrase incubation also significantly reduced the tension and stiffness transients, so that both time courses became monotonic and could be fit with a simple model for cross-bridge detachment. The apparent second-order rate constant for ATP-induced rigor cross-bridge detachment measured in the apyrase treated tissue at 4 x 10(4) M-1 s-1 was faster than that measured in untreated tissue. Nevertheless, this rate was still over an order of magnitude slower than the analogous rate measured in previous studies of isolated cardiac actomyosin-S1. These results are consistent with the hypothesis that the presence of MgADP bound cross-bridges suppresses the inhibition normally imposed by the thin filament regulatory system in the absence of calcium ions and allows cross-bridge rebinding and force production during relaxation from rigor.

Actomyosin↗

PubMed1995

Parallel inhibition of active force and relaxed fiber stiffness by caldesmon fragments at physiological ionic strength and temperature conditions: additional evidence that weak cross-bridge binding to actin is an essential intermediate for force generation.

Previously we showed that stiffness of relaxed fibers and active force generated in single skinned fibers of rabbit psoas muscle are inhibited in parallel by actin-binding fragments of caldesmon, an actin-associated protein of smooth muscle, under conditions in which a large fraction of cross-bridges is weakly attached to actin (ionic strength of 50 mM and temperature of 5 degrees C). These results suggested that weak cross-bridge attachment to actin is essential for force generation. The present study provides evidence that this is also true for physiological ionic strength (170 mM) at temperatures up to 30 degrees C, suggesting that weak cross-bridge binding to actin is generally required for force generation. In addition, we show that the inhibition of active force is not a result of changes in cross-bridge cycling kinetics but apparently results from selective inhibition of weak cross-bridge binding to actin. Together with our previous biochemical, mechanical, and structural studies, these findings support the proposal that weak cross-bridge attachment to actin is an essential intermediate on the path to force generation and are consistent with the concept that isometric force mainly results from an increase in strain of the attached cross-bridge as a result of a structural change associated with the transition from a weakly bound to a strongly bound actomyosin complex. This mechanism is different from the processes responsible for quick tension recovery that were proposed by Huxley and Simmons (Proposed mechanism of force generation in striated muscle. Nature. 233:533-538.) to represent the elementary mechanism of force generation.

Actins↗

PubMed1993

Case report: imaging of widespread plexiform neurofibromatosis.

Although the cutaneous, bony and retroperitoneal appearances of peripheral von Recklinghausen neurofibromatosis are well known, involvement of intra-abdominal organs and of the mediastinum is less well recognised. We present the case of a woman with peripheral neurofibromatosis who presented with loin pain. In addition to cutaneous neurofibromas, plexiform neurofibromas were present in the mediastinum, liver, mesentery and psoas muscles.

Adult↗

PubMed1986

Organ envelopment in lymphoma visualised by computed tomography.

In 12 patients computed tomography revealed an unusual pattern of lymphomatous growth resulting in envelopment or engulfment of an organ. The kidneys were involved in eight cases, and the mediastinum and pericardium, oesophagus, stomach and rectosigmoid colon, and psoas muscle in one case each. Ten patients had non-Hodgkin's lymphoma and two had Hodgkin's disease; in every case, lymphomatous masses surrounded but did not destroy the affected tissues. The potential for both Hodgkin's and non-Hodgkin's lymphomas to enwrap both renal and non-renal tissues has not previously been emphasised.

Adult↗

PubMed2003

Self-inflicted abdominal stab wounds.

BACKGROUND: Self-inflicted abdominal stab wounds (ASWs) are uncommon. The present study aims to characterize the clinical profile of this unique group of psychiatric-surgical patients. METHODS: A retrospective review of 23 patients with intentional self-inflicted ASWs at two urban level I trauma centres during a 10-year period. RESULTS: Most patients were males (70%), ages ranging from 21 to 82 years (mean 40 years). Seventy-four percent of patients had a previous psychiatric history and prior suicide attempts were common (41%). Half of the patients had a positive admission drug or alcohol screen. Hypotension (systolic blood pressure (SBP) < 90 mmHg) was present in only two patients. Mean injury severity, revised trauma and Glasgow coma scores were 5.8, 7.7 and 14.5, respectively. The most commonly used instrument was a knife (87%). There were 1.5 external wounds per patient located primarily in the right upper quadrant (40%) and right lower quadrant (23%). These were associated with extra-abdominal wounds in 22% of cases. Local wound exploration was positive in 15 patients (65%), who all underwent laparotomy. Injured intra-abdominal or retroperitoneal organs were identified in 10 patients and included the stomach, duodenum, small bowel, colon, mesentery, inferior vena cava (IVC) and psoas muscle with a mean of 1.7 injuries per patient. Wound infection was the only post-operative complication (two patients). All eight patients with a negative local wound exploration were observed without complication. Seventy percent of patients were ultimately transferred to a psychiatric ward with a mean length of stay on the surgical service of 8 days. Only one patient died during admission due to metastatic malignant disease. CONCLUSION: Self-inflicted ASWs in suicidal patients can induce significant although most likely non-lethal abdominal and retroperitoneal injuries. This observation should guide the trauma surgeon when treating such patients.

Abdominal Injuries↗

PubMed1991

Ileocecocystoplasty for the management of refractory neurogenic bladder: surgical technique and urodynamic findings.

A total of 21 incontinent adults with a neurogenic bladder who were refractory to conservative management underwent a modified technique of ileocecocystoplasty. Followup ranged from 1 to 6 years (mean 3.1 years). To ensure a wide anastomosis the augmentation was accomplished by suturing a detubularized ileocecal patch to a large posterior based bladder flap anchored to the psoas muscles. Postoperatively 20 of 21 patients were continent. The remaining woman was cured after surgical correction of sphincteric incontinence. Mean bladder capacity increased from 185 +/- 17 to 595 +/- 43 ml. (standard error). Mean maximum detrusor pressure decreased from 53 +/- 6.3 to 16 +/- 2.3 cm. water (p less than 0.0001). Followup revealed a persistently large capacity, low pressure reservoir in all patients. No patient required anticholinergic medication. None experienced acid-base imbalance, tumors in the augmented bladder or upper tract deterioration. We conclude that this technique of ileocecocystoplasty is suitable for the management of patients with a refractory neurogenic bladder.

Adult↗

PubMed1987

Primary psoas abscess.

Infectious processes in the retroperitoneal space often involve the psoas muscle. These infections usually are secondary to other intra-abdominal or intrapelvic inflammatory processes but rarely they will arise primarily within the retroperitoneum. These primary infections occur most often in younger patients and usually will demonstrate a chronic illness in which the diagnosis often is missed. We describe a 22-year-old man with a 2-year history of symptoms before the diagnosis was confirmed. The clinical presentation of the process and pathophysiology are discussed briefly.

Abscess↗

PubMed1980

Metastases from transitional cell carcinoma of the bladder masquerading as psoas abscess.

Metastases from transitional cell carcinoma of the bladder usually progress in a stepwise fashion. We report that first case of metastasis to the body of the psoas muscle. No evidence of retroperitoneal lymphatic involvement or direct extension was identified. Furthermore, the original tumor was superficial but the history was complicated by perforation of the bladder during resection.

Abscess↗

PubMed2004

[Resection of a retroperitoneal schwannoma by a combined approach].

BACKGROUND AND PURPOSE: We report a remarkable case of retroperitoneal schwannoma with significant spinal growth illustrating the effectiveness of a combined surgical approach. METHODS: A 41-year-old man presented with a long history of back pain and unexplained weight loss. An abdominal mass was found in the right upper quadrant. The CT-scan revealed a partially cystic lesion located in the right psoas muscle. Spinal extension was noticed through the L1-L2 neural foramen. MRI better showed the wide rostro-caudal extension in the spinal canal. RESULTS: Bilateral L1 and L2 laminectomy was performed to remove the spinal portion of the tumor. It was extradural but attached to the dura. The roots were not infiltrated. The retroperitoneal mass was removed by an anterior transperitoneal approach. The histological examination did not reveal criteria of malignancy. CONCLUSIONS: Retroperitoneal schwannomas are rare and their preoperative diagnosis remains difficult. In case of significant spinal growth, a combined surgical exposure should be preferred to allow total removal of the lesion and control of the neurological structures.

Adult↗

PubMed2004

[Spontaneous muscular haematomas in hemiplegic patients receiving anticoagulation therapy].

INTRODUCTION: Muscular hematomas are frequently reported as a complication of anticoagulation therapy. METHODS: We report six cases of spontaneous muscular hematomas occurring in hemiplegic patients receiving anticoagulation therapy using heparin, low-molecular-weight heparin or fluindione. Anticoagulation therapy was given in prophylactic doses to two patients to prevent deep vein thrombosis and in therapeutic doses to four patients with deep vein thrombosis, pulmonary embolism or cardiac arrhythmia. Two patients experienced episodes of bleeding when heparin and fluindione were temporarily associated. RESULT: Contrary to previous reports, the more frequent site of bleeding was not the ilio-psoas muscle (only 2 patients); hematomas were also observed in hip adductors and gluteus muscles. The most striking finding was the constant location of the hematoma on the hemiplegic side. CONCLUSION: Location on the hemiplegic side can lead to underestimating the frequency of neurologic compression by the hematoma; the diagnosis can nevertheless be established by electromyography. Local signs may not be present, but general signs of hypovolemia and anemia are more frequent. Ultrasound may be the first line investigation but in our experience, the results can be misleading and computed tomography (CT) or MRI are often required to confirm the diagnosis.

Adult↗

PubMed2001

Laparoscopic and computed tomography-guided percutaneous radiofrequency ablation of renal tissue: acute and chronic effects in an animal model.

OBJECTIVES: To evaluate the laparoscopic and percutaneous delivery of impedance-based radiofrequency ablation (RFA) of the kidney by studying the acute and chronic clinical, radiographic, and histopathologic effects in the porcine model. METHODS: Eight kidneys from 4 pigs underwent laparoscopic RFA. Six kidneys from 3 additional pigs received computed tomography (CT)-guided, percutaneous RFA. CT scans were performed immediately after RFA and before harvest at 2 hours, 24 hours, 3 weeks, and 13 weeks. The gross, radiographic, and histopathologic changes were recorded for each period. RESULTS: Grossly, the RFA lesions were sharply demarcated, measuring 3 to 5 cm. Two major complications (14%) occurred (one urinoma, one psoas muscle injury) in 14 ablations. No deaths or significant blood loss occurred as a result of RFA. Radiographically, the immediate CT scanning demonstrated small perinephric hematomas and wedge-shaped defects. Delayed CT showed nonenhancing defects up to 5 cm. Color-flow and power Doppler were unable to distinguish significant tissue changes during RFA. The histopathologic evaluation revealed marked inflammation surrounding the necrotic regions in the early lesions; chronic lesions were characterized by dense fibrosis. The tissue temperatures ranged from 62 degrees to 118 degrees C in the area of ablation. CONCLUSIONS: RFA is readily delivered laparoscopically or percutaneously with minimal morbidity. Impedance-based application of radiofrequency energy allows monitoring and control of ablation. Using a multi-antenna probe, areas of tissue up to 5 cm can be completely destroyed. The RFA lesion can be monitored as a nonenhancing cortical defect on CT.

Animals↗

PubMed1999

Retroperitoneoscopic renal surgery: our approach.

INTRODUCTION: In the United States and Europe, the retroperitoneoscopic approach to renal surgery has generally been less popular than the transperitoneal laparoscopic approach, primarily because of its "smaller" working space and surgeons' relative unfamiliarity with the optimal operative technique. Presented herein are our current techniques, developed in more than 400 retroperitoneoscopic renal procedures at two major centers performing urologic laparoscopic surgery. TECHNICAL CONSIDERATIONS: Creation of an adequate working space in the retroperitoneum outside of, and posterior to, Gerota's fascia is a critical first step. At one institution, this working space is created with a balloon dilator; at the other, finger dissection is employed for this purpose. A longitudinal incision is made in Gerota's fascia, parallel and close to the psoas muscle, to access the renal hilum. During nephrectomy, the renal hilum is approached initially, followed subsequently by mobilization of the specimen. CONCLUSION: Retroperitoneoscopy allows superb, early access to the renal hilum while avoiding the peritoneal cavity, and is our preferred approach for performing most laparoscopic renal surgery, including radical nephrectomy for cancer. The techniques we describe have made retroperitoneoscopy a dependable, user-friendly, and routine approach for minimally invasive surgery of the kidney at our two centers.

Humans↗

PubMed2005

[Actinomycosis of the buttock].

INTRODUCTION: Cutaneous actinomycosis of the buttocks is a rare granulomatous bacterial infection that usually starts in the perianal area. We present an exceptional case in the form of a pseudo-tumor. CASE REPORT: A 69 year-old woman, in general good health, developed an indurate mass on the supra-external quadrant of the right buttock. The tumor was centered by an ulcerated nodule with a diameter of around 10 centimeters. Imaging showed invasion of the soft tissue of the skin in the internal psoas muscle, the adipose tonality of which was compatible with a liposarcoma. The skin biopsy revealed characteristic bacterial grain in the center of a cholesterol granuloma. Subsequent culture in aerobic milieu identified Actinomyces gerencseriae. Cure was obtained following complete exeresis of the fibrous tissue and 8 months of antibiotic amoxicillin-clavulanic acid therapy. DISCUSSION: Other than the most unusual clinical aspect, the originality of this case of actinomycosis of the buttocks is based on its potential appendix origin, 4 years after acute appendicitis, with slow posterior fistulation. Other cases of actinomycosis of appendix origin have been reported and its delayed onset following the intervention has been documented. The pseudo-sarcomatous aspect was responsible for diagnostic wandering. The histological image and, subsequently, the results of the bacteriological culture confirmed the diagnosis.

Actinomyces↗

PubMed2001

Spontaneous retroperitoneal hemorrhage secondary to subcapsular renal hematoma: MRI findings.

Spontaneous retroperitoneal hemorrhage is a rare intraabdominal bleeding. In this report we present a case of a nontraumatic retroperitoneal hemorrhage secondary to spontaneous subcapsular renal hematoma. A 54-year-old patient who was under warfarin therapy, developed subcapsular right renal hematoma. Subcapsular and retroperitoneal hemorrhage were low signal on T1- and T2-weighted images consistent with acute stage of blood. The source of subcapsular hematoma was shown to be the rupture of hemorrhagic renal cyst on MRI. Extension of hemorrhage into the retroperitoneal space anterior to right psoas muscle was also successfully shown on MRI. Patient underwent nephrectomy and retroperitoneal blood was evacuated.

Hematoma↗

PubMed1992

[Thrombosis of the superior vena cava after prolonged catheterization. Treatment by progressive removal of the catheter combined with urokinase-heparin administration].

A retrospective study of 13 cases of complete superior vena cava thrombosis due to prolonged catheterization is reported. All the polyurethane catheters had been inserted by anaesthetists in theatre between January 1985 and December 1989, using Seldinger's technique. On the 10th day after the first catheter had been placed, the catheter was replaced by using a guide wire. Superior vena cava obstruction was diagnosed clinically (eyelid, neck, facial and upper limb oedema, cyanosis, collateral venous circulation, lack of blood reflux in the catheter). The clinical diagnosis was confirmed by phlebography. Treatment consisted in administration of urokinase (1,500 IU.kg-1.h-1), together with 10,000 to 25,000 IU.day-1 of heparin, both being injected via the catheter. The catheter was removed progressively (1 cm every 2 to 4 h). As soon as a venous pressure curve was obtained, the catheter was completely removed. Overall 8,784 catheters were inserted during that period. The incidence of superior vena caval obstruction may therefore be estimated to be 1.48 per 1,000 catheters. The catheters remained in place up to a mean of 14.75 +/- 9.6 days before the obstruction occurred. Treatment with urokinase and heparin lasted a mean of 2.53 +/- 1 days. The clinical picture returned to normal in all 13 patients. Phlebography carried out in three of them, after treatment, showed an excellent degree of venous repermeability. Thrombolysis was confirmed by the increase in the concentration of D-dimers, without any decrease in fibrinogen concentration. There were five haemorrhagic complications, including two haematomas of the psoas muscle, one of which required surgical drainage.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed2001

Peroxynitrite-modified 99mTc-beta-VLDL: tissue distribution and plasma clearance rate.

Free radicals superoxide (O(2)(-)) and nitric oxide (*NO) are generated by blood vessels and can rapidly react to produce a peroxynitrite anion (ONOO(-)), a powerful oxidant that modifies lipoproteins making them more atherogenic. The aim of this study was to investigate the effect of peroxynitrite-induced modifications on beta-very-low-density lipoprotein (beta-VLDL) as to its biodistribution and plasma clearance rate, as well as the uptake of these particles by THP-1 cells. After being injected into New Zealand White rabbits, the peroxynitrite-modified beta-VLDL (99mTc-per-beta-VLDL) was cleared from circulation faster than the native beta-VLDL (99mTc-nat-beta-VLDL) in both normocholesterolemic rabbits (NC) and in hypercholesterolemic rabbits (HC). In HC rabbits, the fractional clearance of 99mTc-labeled beta-VLDL was significantly lower than in NC rabbits. The in vivo studies showed that accumulation of 99mTc-labeled beta-VLDL, expressed per gram of tissue, followed the decreasing order: kidney > liver > spleen > adrenal gland >or= lung > aortic arch > heart >or= abdominal aorta > thoracic aorta > psoas muscle. The high accumulation in the kidneys suggests the processing of 99mTc-labeled apolipoproteins by receptors present in kidney cells. The accumulation of 99mTc-nat-beta-VLDL in the whole organ was the following: liver > kidney > heart > spleen > adrenal gland > aorta in HC and NC rabbits. The uptake of 99mTc-per-beta-VLDL by the spleen was greater than the uptake by the heart in both groups. The in vitro studies showed that the uptake of 99mTc-per-beta-VLDL by THP-1 cells was higher than that of 99mTc-nat-beta-VLDL. These results show that peroxynitrite-modified beta-VLDL is rapidly removed from plasma and accumulates in several tissues, mainly in the liver and kidney. This may be particularly important in hypercholesterolemic situations that could favor the accumulation of native and peroxynitrite-modified beta-VLDL in several tissues.

Animals↗

PubMed1998

Massive retroperitoneal hemorrhage associated with femoral vein cannulation.

The right external iliac artery was inadvertently punctured during attempted right femoral vein catheterization. Severe hypotension developed several minutes after the arterial puncture. Concurrently, a large right lower abdominal quadrant swelling (approximately 5 cm in diameter) became apparent. Laparoscopic observation of the retroperitoneal region immediately revealed massive retroperitoneal hemorrhage. Abdominal computerized tomographic scan indicated development of a huge (approximately 10 cm in the maximum diameter) retroperitoneal hematoma along the right psoas muscle from the level of the right external iliac vessels up to the level of the upper pole of the right kidney. Consideration of the anatomy of the "right" femoral and retroperitoneal vessels (ie, mediolateral relationship between the vein and artery) led us to conclude that the site for insertion of the needle was too proximal and the angle for advancement of the needle too low in our patient, allowing the needle to reach and injure the "incompressible" external iliac artery, thereby causing massive retroperitoneal hemorrhage. Although femoral vein catheterization has generally been considered a relatively safe method of intravenous access, a life-threatening serious complication can occur with the inappropriate technique used in our case.

Catheterization, Peripheral↗

PubMed2005

Ten-year experience with surgical repair of mycotic aortic aneurysms.

BACKGROUND: Mycotic aneurysm remains a lethal pathologic entity, especially when rupture occurs. It may result from primary aortitis, be induced by septic emboli, or be secondary to an adjacent infection, such as pancreatitis or a psoas muscle abscess. Surgical intervention is the only way to treat such disease. Even when successful repair is achieved by insertion of an interposition in situ graft or by performance of an extra-anatomic bypass, the prognosis is poor. The aim of this study was to present our experience of managing mycotic aortic aneurysms during the past 10 years. METHODS: From January 1994 to June 2004, a total of 734 patients with aortic aneurysms underwent surgical repair at our institution. Among these cases, 17 (2.3%) were shown to be mycotic aneurysms of the ascending aorta (n = 1), aortic arch (2), thoracic and thoracoabdominal aorta (3), or abdominal aorta (11); 14 patients (mean age, 58.8 years) were male. Preoperative imaging studies were performed in all patients. Mycotic aortic aneurysms were suspected in 12 of the 17 patients (70.6%) preoperatively, and 4 of these 12 patients were found to have ruptures on imaging. At the time of surgery, 9 of the 17 aneurysms (52.9%) were ruptured. Fifteen patients had an interposition graft inserted after meticulous debridement, 1 underwent an aorto-aortic bypass, and 1 underwent an extra-anatomic (axillo-femoral) bypass. An omentum patch was applied to wrap the graft in 8 of 11 mycotic aortic aneurysms of the abdominal aorta. The most common pathogens were Salmonella spp. (n = 7) and Staphylococcus spp. (4). All patients received antibiotic therapy, according to the culture report, for about 4-6 weeks postoperatively. RESULTS: In-hospital mortality was 11.8% (n = 2). Another patient died from massive upper gastrointestinal bleeding 6 months after operation because of complications involving an aorto-duodenal fistula, and another died from stomach cancer 6 years after surgery. Long-term follow-up (mean, 37 months; range, 3-111 months) revealed that, at the time of writing, the remaining 13 patients were alive and well, without any recurrence of aneurysm. CONCLUSION: Mycotic aneurysm of the aorta is a life-threatening disease, especially when rupture occurs. The high mortality rate is due not only to the high rupture rate, but also to sepsis. When mycotic aortic aneurysm is diagnosed, early surgical intervention is mandatory.

Adult↗