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At least 307 records · Page 17Linked to original sources
PubMed1997

Transcranial color-coded duplex sonography in the evaluation of collateral flow through the circle of Willis.

PURPOSE: To determine the sensitivity, specificity, and positive and negative predictive values of transcranial color-coded duplex sonographic (TCCD) evaluation of cross flow through the anterior (ACoA) and posterior (PCoA) communicating arteries in patients with occlusive cerebrovascular disease. METHODS: We studied prospectively 132 patients (37 women, 95 men; mean age, 60 years) with stenoses of more than 69% reduction in vessel diameter (n = 93) and occlusions (n = 52) of the internal carotid artery, and three occlusions of the basilar artery. The sonographer was aware of extracranial sonographic findings but was blinded to the results of cerebral angiography. RESULTS: Nine patients (7%) with thick bones preventing transtemporal insonation and three patients (3%) with occlusions of the middle (n = 3) and anterior (n = 1) cerebral arteries were excluded. Sensitivity of TCCD for detection of collateral flow through the ACoA in patients with occlusive carotid artery disease was 98%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 98%. The corresponding values for the PCoA were 84%, 94%, 94%, and 84%, respectively. All three functional PCoAs were identified in patients with occluded basilar arteries. CONCLUSION: TCCD is a valuable method for noninvasive evaluation of cross flow through the ACoA in patients with adequate sonographic windows. However, TCCD evaluation of cross flow through the PCoA is less reliable, because hemodynamic criteria may cause falsely positive and falsely negative results.

Adult↗
PubMed2002

Measurement of ulnar flow is helpful in predicting ischemia after radial artery harvest.

BACKGROUND: Despite a negative Allen test, some patients develop hand ischemia after radial artery harvesting. The presence of large interosseous collaterals may reduce the sensitivity of Allen test. To evaluate the combination of ulnar flow measurements and the Allen test as an effective screening technique, we performed Doppler ultrasonography during Allen's maneuver. METHODS: The Allen test was used to select candidates for harvesting radial artery from 80 patients undergoing coronary bypass surgery. RESULTS: Of 71 patients with a negative Allen test, one patient developed hand ischemia. This patient was one of six (7.5 %) possessing low ulnar flow levels (less than 40 ml/min/m(2) during compression of the radial artery). This low-flow group had a higher risk for ischemia of the 71 patients with a negative Allen test. The post-operative flow differed greatly from the pre-operative flow in eight patients (11.3 %), which was likely due to large sacrificed interosseous collaterals. CONCLUSION: Combined use of ulnar flow measurement with the Allen test appears to increase the sensitivity of the Allen test. Neither test, however, is sufficient for a group of patients with large interosseous collaterals.

Coronary Artery Bypass↗
PubMed1985

Retrograde tracing of neural pathways with a protein gold complex. II. Electron microscopic demonstration of projections and collaterals.

This paper describes a sensitive method for tracing neural connections at the electron microscopic (EM) level using a new compound produced through the coupling of colloidal gold particles to a wheat germ agglutinin horseradish peroxidase conjugate (the WGA*HRP-gold complex). Visualization of retrogradely labeled cells at the EM level was achieved either directly by gold particles scanning or after silver enhancement. By using different sizes of gold particles individually coupled to WGA*HRP and injected in different brain areas EM detection of multiple retrograde labeling was possible. Thus retrogradely labeled cells were first identified at the light microscopic level through HRP histochemistry with tetramethylbenzidine as a chromogen and then examined under the electron microscope after osmication and embedding. Gold particles were readily identified as electron dense, round dots in spherical grey vesicles. Identification of different sizes of gold particles often localized in the same vesicle established that the protein-gold complex can be used to study collateralisation of parental axons.

Animals↗
PubMed2006

Central line-associated venous late effects in children without prior history of thrombosis.

BACKGROUND: The frequency of asymptomatic central line-associated thromboses is high and well recognized among children with cancer, while the long-term consequences are mainly unknown. AIM: In a cross-sectional study, we evaluated clinical and radiological venous outcome in children with previous long-standing intravascular catheters. METHODS: The study enrolled 71 children previously treated for malignant or haematological diseases, 4-180 (median 37) mo after removal of their central lines. Inclusion criteria were a prior central line in a jugular vein for a minimum of 6 mo and no previous history of thrombosis. The children had clinical examination for post-thrombotic syndrome (PTS) and Doppler ultrasonography of the central neck veins. Twelve children had additional venous magnetic resonance imaging (MRI). But no kind of venography was performed in the remaining. RESULTS: We observed mild PTS with increased superficial collaterals in four children (6%), but no cases of more severe PTS. None complained of symptoms related to venous late effects. By ultrasonography, post-thrombotic venous alterations were detected in 17 children (24%), and five of these had complete occlusion of the veins. The sensitivity for pathologically increased collaterals to identify occlusive thrombosis was 0.6, while the specificity was 0.98. Occlusive venous thromboembolism was associated with the total number of central venous lines (CVLs; p=0.002), previous severe CVL-associated infections (p=0.001) and duration of central line in place (p=0.042). CONCLUSION: In spite of no prior history of thrombosis, children with previous long-term jugular lines frequently had local thrombotic sequelae, while clinical symptoms of PTS were rare.

Catheterization, Central Venous↗
PubMedDate not supplied

Response of peripheral collateral arteries in the dog to prostaglandins E1, E2, F2 alpha, and I2 (prostacyclin).

Prostaglandins (PG) E2, E2, E2 alpha, and I2 [prostacyclin (PGI2)] were tested in vitro on collateral arteries that enlarge following chronic occlusion of the femoral artery in the dog. After contraction with an ED50 dose of KCl, serial doses of a PG were added. Collateral arteries relaxed significantly to PGI2 (10(-7)--10(-5) M). Normal, similarly sized branch arteries did not relax. The contractile response of collateral arteries to PGE1, PGE2, and PGF2 alpha was qualitatively similar to that of branch arteries, but the magnitude of the responses for collateral arteries was PGF2 alpha = PGE2 greater than PGE1. The magnitude of the response for branch arteries was PGF2 alpha much greater than PGE2 greater than PGE1. The effects of the PGs on anterior tibial arteries from the contralateral limb and on anterior tibial arteries exposed to low pressure below the occlusion did not differ. Thus the lowered pressure in the limb with the occluded femoral artery was not responsible for differences in the effects of the PGs on collateral arteries. Collateral arteries are more sensitive to the relaxant effects of PGI2 in high doses and are less sensitive to the contractile effects of other PGs, particularly PGF2 alpha, than similarly sized arteries. This suggests that therapeutic doses of PGI2 may increase blood flow to ischemic areas.

Alprostadil↗
PubMedDate not supplied

Elbow medial ulnar collateral ligament insufficiency alters posteromedial olecranon contact.

BACKGROUND: The effect of elbow medial ulnar collateral ligament injury on posteromedial compartment contact is unknown. HYPOTHESIS: Medial ulnar collateral ligament injury causes altered contact area and pressure in the posteromedial compartment of the elbow. STUDY DESIGN: Controlled laboratory study. METHODS: Seven elbow cadaveric specimens were tested in an apparatus that positioned the elbow at 30 degrees and 90 degrees of flexion. Partial and full tears were simulated by releasing the medial ulnar collateral ligament. Pressure-sensitive film was placed in the posteromedial compartment for each condition. Valgus torques of 1.25 and 2.0 N.m were applied for each ligament condition, and kinematic data were obtained at each flexion angle using a 3-dimensional digitizer. RESULTS: Both ligament condition and valgus load had significant effects on contact area and pressure (P<.05). For a given load and flexion angle, the contact area decreased and the pressure increased with increasing medial ulnar collateral ligament insufficiency. Within these trends, statistical significance was found at 30 degrees of elbow flexion for both area and pressure (P<.05); at 90 degrees of elbow flexion, increasing medial ulnar collateral ligament insufficiency did not significantly affect contact area or pressure (P>.05). DISCUSSION: Medial ulnar collateral ligament insufficiency alters contact area and pressure between the posteromedial trochlea and olecranon and helps explain the development of posteromedial osteophytes.

Athletic Injuries↗
PubMed2005

Leg ischemia: assessment with MR angiography and spectroscopy.

PURPOSE: To prospectively determine reproducibility of magnetic resonance (MR) angiography and MR spectroscopy of deoxymyoglobin in assessment of collateral vessels and tissue perfusion in patients with critical limb ischemia (CLI) and to follow changes in patients undergoing intramuscular vascular endothelial growth factor (pVEGF)-C gene therapy, percutaneous transluminal angioplasty, supervised exercise training, or no therapy. MATERIALS AND METHODS: Study and gene therapy protocols were approved, and all patients gave written informed consent. To determine repeatability and reproducibility, seven patients underwent MR angiography and five underwent MR spectroscopy. The techniques were used to judge disease progress in 12 other patients with or without therapy: MR angiography to help determine change in visualization of collateral vessels and MR spectroscopy to help assess change in perfusion at proximal and distal calf levels. MR angiographic results were subjectively analyzed by three blinded readers. Intraobserver variability was expressed as 95% confidence interval (CI) (n=7); interobserver variability, as kappa statistic (n=15). Reexamination variability of MR spectroscopy was given as 95% CI for subsequent recovery times, and correlation with disease extent was calculated with Kendall taub rank correlation. Fisher-Yates test was used to correlate changes with pressure measurements and clinical course. RESULTS: Intraobserver and interobserver concordance was sensitive for detection of collateral vessels. Intraobserver agreement was 85.7% (95% CI: 42.1%, 99.6%). Interobserver agreement was high for small collateral vessels (kappa=0.74, P <.001) and fair for large collateral vessels (kappa=0.36, P=.002). MR spectroscopy was reproducible (95% CI: +/-26 seconds for proximal, +/-21 seconds for distal) and showed a correlation with disease extent (proximal calf, taub=0.84, P <.001; distal calf, taub=0.68, P=.04). Small collateral vessels increased over time (P=.04) but did not correlate with pressure measurements and clinical course. Recovery time correlated with clinical course (proximal calf, P=.03; distal calf, P=.005). CONCLUSION: MR angiography and MR spectroscopy of deoxymyoglobin can help document changes in visualization of collateral vessels and tissue perfusion in patients with CLI.

Aged↗
PubMed1988

Importance of cerebral collateral pathways during carotid endarterectomy.

Before surgery, we evaluated major intracranial collateral pathways using transcranial Doppler ultrasonography (TCD) in 50 patients who then underwent carotid endarterectomy with concurrent multimodality cerebral monitoring. Patients were grouped with respect to collateral pathways demonstrated preoperatively by TCD: Group 1, good collateralization with an anterior and/or posterior communicating artery ipsilateral to the operative carotid lesion (29 patients, 58%); Group 2, collateral pathways present but impeded by other proximal stenoses (nine patients, 18%); and Group 3, no collateralization identified (nine patients, 18%). Three patients (6%) could not be classified. TCD identified major collateral pathways with a sensitivity of 89% and a specificity of 80% when compared with arteriography. During carotid endarterectomy mean middle cerebral artery velocity, pulsatility index, and stump pressure were higher and the decrease in middle cerebral artery velocity with extracranial carotid artery cross clamping was significantly less among Group 1 patients than among Group 2 and 3 patients (p less than 0.05 for both groups). Group 1 patients required fewer intraoperative carotid artery shunts and developed fewer ischemic electroencephalographic abnormalities than did patients in Groups 2 and 3 (p less than 0.05 for both groups). TCD assessment of cerebral collateralization helps predict hemodynamic consequences of cross clamping during carotid endarterectomy.

Aged↗
PubMed2005

[The Omega "Omega" pulley plasty: a new technique for the surgical management of the De Quervain's disease].

The Omega "Omega" pulley plasty: a new technique for the surgical management of the De Quervain's disease. The De Quervain tenosynovitis is an inadequacy into the first extensor compartment between the osteo-fibrous tunnel and the tendons. This mechanical conflict generates a tenosynovitis of the extensor pollicis brevis and the abductor pollicis longus tendons. This is generally expressed by a tenderness on the radial side of the wrist over the radial styloid process. The medical management consists on corticoids infiltrations of the first extensor compartment, the avoidance of repetitive and stress movements of the first ray with the use of a rest splint. The surgical approach is considered with the recurrence of the painful symptoms. This well-known pathology is reputated to require a simple section of the pulley. Our post-operative complications have been reported in the literature of this classical surgical solution. These complications concern an incomplete release of the extensor pollicis brevis and the abductor pollicis longus tendons particularly when an extensor sub-compartment exists and was overlooked, an irritation of the collateral branches of the sensitive radial nerve or the occurrence of a nevroma after a nerve injury and the most serious complication is a palmar subluxation of the extensor tendons which can occur with the thumb extended and the wrist flexed. In rare cases, this subluxation can be really painful and requires a surgical management with secondary reconstruction of the pulley. This reconstruction necessitates distal pedicle flaps from the dorsal retinaculum or the brachioradialis tendon. To prevent these complications, Codega and Kapandji described techniques of reconstruction of the pulley after its release. More recently, Le Viet reported a procedure using the anterior flap of the pulley; fixed to the dermis it will work as a barrier and maintain the tendons sliding on the radial styloid groove. These techniques require to divide the pulley and to reconstruct it suturing the different flaps. It can generate adherences between the extensor tendons, the overlying skin and the collateral branches of the radial nerve. The authors present a new and original plasty procedure of the first extensor compartment pulley, the "Omega" Omega plasty. It consists to liberate the anterior attachment of the pulley over the anterior lip of the styloïd process respecting its continuity with the periosteum flap. This conservative procedure is very interesting; it permits enough expansion of the tunnel volume decompressing the extensor tendons as a treatment of the De Quervain disease and respecting the anatomy and the continuity of the osteo-fibrous tunnel. This technique is simple, reliable and respects the first ray extensor tendons gliding physiology and biodynamic. In spite of our short clinical experience with only ten cases, all the patients retrieve a normal function of the thumb with complete disappearance of the first ray tenderness and pain without any complications. These preliminary results are encouraging and push us to consider the "Omega" plasty as a first choice for the surgical treatment of the De Quervain tenosynovitis.

Humans↗
PubMed1983

Sonography of portosystemic venous collaterals in portal hypertension.

Portosystemic venous collaterals were studied with sonography in 40 patients with known portal hypertension. Eight patients had technically inadequate scans, while 32 had optimal scans. Sixty groups of venous collaterals were identified. At least one collateral pathway was seen in 28 patients, for a sensitivity of 88% for the 32 patients with optimal scans and 70% for the total group. The overall sensitivity for detection of coronary-gastroesophageal collaterals was 80% and 64%, respectively. The small size of the coronary-gastroesophageal varices in early portal hypertension seems to be the most important factor limiting detection in patients suitable for sonography.

Collateral Circulation↗
PubMed1993

The role of the saphenous nerve in experimental sciatic nerve mononeuropathy produced by loose ligatures: a behavioural study.

Four loose ligatures were tied round the sciatic nerve of rats to produce the model of altered pain sensation first described by Bennett and Xie (1988). Hyperalgesia and hyperaesthesia were detected from 4 days after tying ligatures, becoming maximal after 14 days; normal behaviour returned by 8 weeks post-operation. Using thermal tests involving immersion of the whole foot, it was found that section of the saphenous nerve at the time of, or within a week of, placing ligatures had the effect of abolishing the hyperaesthetic behaviour and instead caused hypoaesthesia from the 4th to 10-12th days. There was then a change to hyperaesthetic behaviour. The findings are interpreted as indicating that the early hyperaesthesia is possibly due to collateral sprouting, spreading nociceptor sensitivity of saphenous nerve fibres or both of these.

Animals↗
PubMed2001

Mutagenesis of dihydrofolate reductase from Plasmodium falciparum: analysis in Saccharomyces cerevisiae of triple mutant alleles resistant to pyrimethamine or WR99210.

Inhibitors of dihydrofolate reductase (DHFR) have been a mainstay of chemotherapy of falciparum malaria for >50 years. Unfortunately, point mutations in DHFR are the major cause of resistance to drugs of this class and mutations have rapidly diminished the clinical effectiveness of these drugs. We designed a simple yeast-based system to produce and analyze point mutations in the Plasmodium falciparum DHFR domain of the DHFR-thymidylate synthase gene that confers resistance to pyrimethamine (PM), the major antifolate currently used in malaria treatment, or to WR99210, an experimental antifolate. We used PCR mutagenesis, screened >1000 DHFR alleles that encoded functional enzymes and studied approximately 100 that were more resistant than a naturally occurring resistant allele (N51I and S108N). The IC(50) values for both drugs were determined for a subset of 44 alleles that carried only a single new mutation. Mutations that increased resistance to PM 10-100 fold (to >10(-4) M) were identified in three regions of the DHFR domain - around amino acids 50, 188 and 213. In contrast, mutations that caused WR-resistance were far less common and only conferred approximately 10-fold resistance (to approximately 10(-7) M). Even more interesting, only the mutations at 188 increased resistance to WR and mutations in the 213 and other regions either had no effect or actually increased sensitivity to WR. This collateral hypersensitivity raises the possibility that opposing selection for resistance/sensitivity to PM and WR might be used to slow selection of populations of P. falciparum resistant to antifolate treatment.

Alleles↗
PubMed1980

Tomographic assessment of cerebral perfusion using a single-photon emitter (krypton-81m) and a rotating gamma camera.

Continuous carotid infusion of short-lived krypton-81m (t1/2 13 sec) yields an assessment of regional cerebral perfusion. This assessment can be obtained in three dimensions if activity is recorded with a rotating gamma camera and a computer to reconstruct krypton-81m distribution in tomographic sections. These showed several advantages over conventional views: (a) visualization of blood-flow distribution within brain structures (gray and white matter, basal ganglia); (b) more accurate location and evaluation of areas of relatively reduced or increased perfusion; (c) better definition of patterns of collateral circulation; (d) greater sensitivity and specificity in detecting and defining blood-flow changes during physiological activation studies. A limitation of the krypton-81m technique is its invasiveness. However, this study shows that the combination of new advances in radiochemistry with single-photon emission computed tomography may result in accessible methods for assessing, noninvasively and in three dimensions, the behavior of cerebral function in man.

Brain Diseases↗
PubMed1981

[Value of dipyridamole test in the diagnosis of ischemic heart disease].

The diagnostic test with dipyridamol was carried out in 83 patients with ischaemic heart disease (IHD) and cardialgias of various genesis, with diagnosis verified by coronarography and veloergometry. IHD patients after dipyridamol had angina pectoris attacks with or without ischaemic changes on ECG, which points to latent coronary insufficiency. The appearance of an anginal attack with the depression of the ST segment is typical of IHD with stenosing coronary atherosclerosis, as a rule, with developed collateral vessels. As to sensitivity and specificity in detecting IHD the dipyridamol test is equal to the bicycle ergometry tests. With the results of both tests considered the frequency rate of detection of IHD is increased. The dipyridamol test is recommended for diagnosis of IHD in therapeutic and cardiological hospitals.

Adult↗
PubMed1988

Changes in drug sensitivity of a human astrocytoma clone previously treated with 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea in vitro.

We have shown in earlier studies that repeated weekly exposures of a human astrocytoma clone (AST 3-4) to MeCCNU (10 micrograms/ml for 1 h per week) produced a linear decrease in survival over the first 3 weekly treatments. But, after that time these cells became progressively more resistant to the 10 micrograms/ml concentration of the agent. In the studies reported here we show that these previously treated cells were also less responsive to other doses ranging from 1 to 30 micrograms MeCCNU/ml. This change in sensitivity to MeCCNU was accompanied by collateral changes in response to other agents: resistance to BCNU and Galactitol, increased sensitivity to Adriamycin, and no change to ionizing radiation. These experiments suggest that once repeated treatments with a single agent cause a tumor cell population to become more resistant, sensitivity to other agents may also change unpredictably.

Astrocytoma↗
PubMed2005

Differential sensitivity to NO-induced apoptosis between anterior cruciate and medial collateral ligament cells.

It is well known that the anterior cruciate ligament (ACL) of the knee joint has poorer healing responses than the medial collateral ligament (MCL). Nitric oxide (NO) induces free radicals and plays a key role in the induction of apoptosis in various wound-healing models. We hypothesized that the poor healing response of the ACL may be ascribed to high susceptibility to apoptosis, and we investigated the difference in susceptibility to apoptosis between ACL and MCL cells after treatment with sodium nitroprusside, a NO donor. Apoptosis was evaluated by phase contrast microscopy, electron microscopy, DNA gel electrophoresis, and flow cytometric analysis. Although morphological changes and DNA ladders were observed in both ACL and MCL cells after 2 mM sodium nitroprusside treatment, ACL cells were more prone to apoptosis at 1 mM. Based on flow cytometric analysis, DNA fragmentation at 1 mM sodium nitroprusside was significantly greater in ACL cells than in MCL cells (58.6% +/- 1.6% vs. 11.9% +/- 2.2%). Caspase-3 inhibitor (Ac-Asp-Glu-Val-Asp-CHO) and caspase-9 inhibitor (Ac-Leu-Glu-His-Asp-CHO) completely inhibited this DNA fragmentation. In conclusion, the ACL and MCL cells exhibit essential differences, and the differential sensitivity to NO-induced apoptosis between the ACL and MCL cells may be a reflection of these differences.

Animals↗
PubMed1999

Combined assessment of reflow and collateral blood flow by myocardial contrast echocardiography after acute reperfused myocardial infarction.

OBJECTIVE: To evaluate the combined assessment of reflow and collateral blood flow by myocardial contrast echocardiography after myocardial infarction. DESIGN: Myocardial contrast echocardiography was performed in patients with acute myocardial infarction shortly after successful coronary reperfusion (TIMI 3 patency) by direct angioplasty. Collateral flow was assessed before coronary angioplasty, and contrast reflow was evaluated 15 minutes after reperfusion. The presence of contractile reserve was assessed by low dose dobutamine echocardiography (5 to 15 micrograms/kg/min) at (mean (SD)) 3 (2) days after myocardial infarction. Recovery of segmental function (myocardial viability) was evaluated by resting echocardiography at a two month follow up. The study was prospective. PATIENTS: 35 consecutive patients referred for acute transmural myocardial infarction. RESULTS: Contrast reflow was observed in 20 patients (57%) and collateral flow in 14 (40%). Contrast reflow and collateral contrast flow were both correlated with reversible dysfunction on initial dobutamine echocardiography and at follow up (p < 0.05). The presence of reflow or collateral flow on myocardial contrast echocardiography was a highly sensitive (100%) but weakly specific (60%) indicator of segmental dysfunction recovery. Simultaneous presence of contrast reflow and collateral flow was more specific of reversible dysfunction than reflow alone (90% v 60%). CONCLUSIONS: Combined assessment of reflow and collateral blood flow enhanced the sensitivity of myocardial contrast echocardiography in predicting myocardial viability after acute, reperfused myocardial infarction. The simultaneous presence of reflow and collateral blood flow was highly specific of recovery of segmental dysfunction.

Adult↗
PubMed1995

Digital high frame rate stress echocardiography for detection of coronary artery stenosis by high dose dipyridamole stress testing.

Diagnostic accuracy of high dose dipyridamole stress echocardiography (0.84 mg i.v./kg) for detecting coronary artery stenosis was assessed in 94 patients undergoing coronary angiography, and adverse effects were registered in the total study population of 120 patients. Echocardiographic analysis was performed with digital systolic cineloops with high frame-rate (47 frames/sec) for optimal left ventricular wall motion display. Results showed sensitivity of 73% for detection of arterial luminal stenosis > or = 75% or retrograde collateral flow to an occluded coronary artery. Sensitivity for detection of 1-vessel stenosis was 43% (6 of 14 patients), and for 2- and 3-vessel disease 79% (19 of 24) and 88% (16 of 18), respectively. Specificity was 92% (35 of 38), diagnostic accuracy 81%. The stenosed coronary artery was correctly localized in 85% of positive tests. Dipyridamole-induced increase in wall motion score index differed significantly between patients with 1-, 2-, and 3-vessel disease (0.02 +/- 0.17, 0.15 +/- 0.17, and 0.27 +/- 0.24, respectively), and early positive tests (dipyridamole dose of 0.56 mg/kg) were almost exclusively seen in patients with multivessel disease. Six patients (5%) developed symptomatic bradycardia and hypotension during the test. In conclusion, dipyridamole stress echocardiography is useful for detection and localization of coronary artery stenosis, particularly in patients with multivessel disease.

Collateral Circulation↗