Magnetic resonance angiography for postnephrectomy arteriovenous fistula.
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Arteriovenous Fistula↗
Biomedical subjects
P J Kitslaar
Publications and source records attributed to P J Kitslaar.
Identification of genes potentially involved in rupture of human atherosclerotic plaques.
Although rupture of an atherosclerotic plaque is the major cause of acute vascular occlusion, the exact molecular mechanisms underlying this process are still poorly understood. In this study, we used suppression subtractive hybridization to make an inventory of genes that are differentially expressed in whole-mount human stable and ruptured plaques. Two libraries were generated, one containing 3000 clones upregulated and one containing 2000 clones downregulated in ruptured plaques. Macroarray analysis of 500 randomly chosen clones showed differential expression of 45 clones. Among the 25 clones that showed at least a 2-fold difference in expression was the gene of perilipin, upregulated in ruptured plaques, and the genes coding for fibronectin and immunoglobulin lambda chain, which were downregulated in ruptured plaques. Reverse transcriptase-polymerase chain reaction analysis on 10 individual ruptured and 10 individual stable plaques showed a striking consistency of expression for the clones SSH6, present in 8 ruptured and 2 stable plaques, and perilipin, expressed in 8 ruptured plaques and completely absent in stable plaques. Localization studies of both perilipin mRNA and protein revealed expression in cells surrounding the cholesterol clefts and in foam cells of ruptured atherosclerotic plaques. No expression was observed in nondiseased artery, and only a few cells in the shoulder region of stable plaques tested positive for perilipin. In conclusion, this study shows that it is possible to identify genes that are differentially expressed in whole-mount stable or ruptured atherosclerotic plaques. This approach may yield several potential regulators of plaque destabilization.
Aged↗
The effect of diabetes and severe ischaemia on the penetration of ceftazidime into tissues of the limb.
AIMS: To determine the effect of diabetes and of different degrees of ischaemia on the penetration of ceftazidime into different tissues. METHODS: Sixteen patients (10 with diabetes mellitus) undergoing lower extremity amputation for severe ischaemia (in 12 in combination with infection), received 2000 mg ceftazidime intravenously as a bolus 30 min prior to the operation. Skin perfusion was determined by transcutaneous oxygen pressure measurements (TcPO2) on the dorsal side of the midfoot. After amputation bone, skin and muscle samples were obtained from the forefoot, midfoot and proximal tibia. Tissue and plasma concentrations were determined by HPLC. The tissue concentrations were corrected for blood contamination. RESULTS: No differences were observed in skin, muscle or bone ceftazidime levels between diabetic and non-diabetic patients. Multiple regression analysis suggested that tissue perfusion was a major determinant of skin and bone ceftazidime concentrations, predicting 40-47% of the ceftazidime concentrations at several biopsy sites. CONCLUSIONS: The present study suggests that tissue perfusion is the major determinant of the penetration of a third generation cephalosporin into the tissues of the ischaemic (diabetic) foot. Diabetes alone however, has no major effects upon this penetration.
Aged↗
Differential expression of bone matrix regulatory proteins in human atherosclerotic plaques.
In the present study, we examined the expression of regulators of bone formation and osteoclastogenesis in human atherosclerosis because accumulating evidence suggests that atherosclerotic calcification shares features with bone calcification. The most striking finding of this study was the constitutive immunoreactivity of matrix Gla protein, osteocalcin, and bone sialoprotein in nondiseased aortas and the absence of bone morphogenetic protein (BMP)-2, BMP-4, osteopontin, and osteonectin in nondiseased aortas and early atherosclerotic lesions. When atherosclerotic plaques demonstrated calcification or bone formation, BMP-2, BMP-4, osteopontin, and osteonectin were upregulated. Interestingly, this upregulation was associated with a sustained immunoreactivity of matrix Gla protein, osteocalcin, and bone sialoprotein. The 2 modulators of osteoclastogenesis (osteoprotegerin [OPG] and its ligand, OPGL) were present in the nondiseased vessel wall and in early atherosclerotic lesions. In advanced calcified lesions, OPG was present in bone structures, whereas OPGL was only present in the extracellular matrix surrounding calcium deposits. The observed expression patterns suggest a tight regulation of the expression of bone matrix regulatory proteins during human atherogenesis. The expression pattern of both OPG and OPGL during atherogenesis might suggest a regulatory role of these proteins not only in osteoclastogenesis but also in atherosclerotic calcification.
Adult↗
[Role of noninvasive vascular function tests before arterial vascular surgery].
Noninvasive functional tests of the arterial circulation are tests mainly based on measurements of systolic blood pressures and pulsatility of the blood flow in the extremities. In nearly all these tests Doppler ultrasound analyses of the arterial blood-stream are used. Objective and numeral data regarding the arterial function are needed both for the indications in arterial vascular surgery and for the analysis of the results of operative and non-operative vascular treatments. Before operations for chronic arterial obstructive disease of the lower extremities and in the case of pathology of the carotid arteries non-invasive functional vascular testing is indispensable. On the other hand, in patients with aneurysmatic disease, vascular trauma or arterial entrapment syndromes haemodynamic tests are almost redundant. The haemodynamic examinations for renal and visceral arterial abnormalities still need further development and validation before their clinical usefulness can be defined.
Abdomen↗
Intimal hyperplasia in vascular grafts.
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Anastomosis, Surgical↗
A new animal model to study intimal hyperplasia in arteriovenous fistulas.
BACKGROUND: Intimal hyperplasia (IH) plays a key role in the failure of arteriovenous (AV) fistulas. The animal models available to study IH in AV fistulas are expensive and do not mimic the development of truly stenotic IH. In this study we examined whether goats are a more suitable model to study IH in AV fistulas. MATERIALS AND METHODS: Thirteen direct and four bridge graft AV fistulas between the carotid artery and the jugular vein of goats were explanted 10 to 195 days after creation. Immunohistochemical staining and morphometric measurements of intima and media were performed in the artery, the vein, the toe, and the heel of the venous anastomosis. Ratios of intimal to medial thickness (Ith/Mth) and area (Ia/Ma) were calculated. RESULTS: IH developed in all goats, mainly at the anastomosis (Ia/Ma = 0.17) and the efferent vein (Ia/Ma = 0.31). The artery was almost free of lesions (Ia/Ma = 0.03). In the efferent vein, Ith/Mth varied between 0.59 and 0.68. In the anastomosis the largest value of Ith/Mth was measured at the suture lines (0.88 and 0.91). Absolute intimal area increased with time. IH contained many vascular smooth muscle cells with a patchy display of desmin positivity, an abundance of smooth muscle cell alpha-actin positivity, and almost complete endothelial cell coverage. Occlusion was due to thrombus formation on the IH. CONCLUSION: A clear intimal hyperplasia developed in AV fistulas in goats at locations comparable to those in humans. Therefore, the AV fistula model in the goat may be seen as an effective model to study IH in hemodialysis AV fistulas.
Animals↗
Biphasic pattern of cell turnover characterizes the progression from fatty streaks to ruptured human atherosclerotic plaques.
OBJECTIVE: To study the amount and phenotype of DNA-synthesizing and apoptotic cells during atherogenesis. METHODS: Atherosclerotic lesions (n = 76), obtained at autopsy (N = 6) or during vascular surgery (N = 8), were classified [type I-VI; American Heart Association (AHA) classification], immunolabeled with MIB 1 or the TUNEL technique and double stained with cell-type-specific antibodies. Subsequently, the labeled fractions were quantified. RESULTS: In type II-VI lesions, intimal DNA synthesis was increased compared to that of the non-diseased (ND) arterial wall. DNA synthesis peaked in early type II lesions (2.7 +/- 0.5 vs. 0.02 +/- 0.02% in ND; p < 0.05), and declined to 0.7 +/- 0.2% in type V lesions (p < 0.05). Interestingly, a second peak of DNA synthesis of 1.7 +/- 0.1%, was observed in type VI (ruptured plaque) lesions. Double staining revealed that DNA synthesis was mostly confined to the macrophage-derived foam cell (51.9%). In type II lesions, 100.0% of all DNA-synthesizing cells were present in the intimal foam cell-rich area, while in advanced type III, IV and V lesions, DNA synthesis had shifted to the shoulder region (74.8, 78.5 and 68.1%, respectively). In type VI lesions, DNA synthesis was present in the area underlying the plaque rupture (52.7%). Apoptosis was only elevated in advanced type IV, V and VI lesions (0.8 +/- 0.1, 0.8 +/- 0.1 and 1.1 +/- 0.1%, respectively, vs. 0.0 +/- 0.0% in ND) and was predominant in the lipid core (90.5% in type IV lesions; 54.2% in type V lesions) or equally divided between the lipid core and the region underlying the plaque rupture (31.8 and 34.6% in type VI lesions). In type III-VI lesions, 50.0, 38.9, 42.6 and 42.8% of the TUNEL-positive cells were macrophages. CONCLUSIONS: In stable atherosclerotic lesions, DNA synthesis is an early event, while apoptosis is a late event. Ruptured plaques show a second peak of cell turnover. Lastly, cell turnover is mostly confined to the macrophage-derived foam cell.
Aged↗
The influence of experience on the reproducibility of the ankle-brachial systolic pressure ratio in peripheral arterial occlusive disease.
OBJECTIVES: to estimate the intra-observer variability of the measurement of the ankle-brachial systolic pressure index (ABPI) and to compare the reproducibility of the measurements by experienced vascular laboratory assistants and by less-experienced general practice personnel. DESIGN: repeated measurement of ABPI by general practitioners (GPs), GP-assistants and vascular laboratory assistants using a pocket Doppler device and a random-zero sphygmomanometer. METHODS AND MATERIALS: ABPI was measured in six patients with various degrees of PAOD by two experienced observers (vascular laboratory assistants) and by 24 less-experienced observers (18 practice assistants, six GPs). RESULTS: the total number of measurements was 354. The overall intra-observer variability estimate was 11.8% ABPI. The intra-observer variability was 7.3% in the experienced observers and 12.0% in the less-experienced observers. The difference of variability between experienced and less-experienced observers was significant. CONCLUSIONS: the ABPI is suitable in follow-up studies where repeated measurements are needed. Differences between measurements can be minimised by performing repeated measurements or by using more experienced observers.
Aged↗
Haemodialysis vascular access and fistula surveillance methods in The Netherlands.
INTRODUCTION: As the mean age of haemodialysis patients is increasing, fewer patients will have suitable blood vessels for the creation of a Brescia-Cimino fistula and an increased use of graft implants is to be expected. METHODS: To assess the change in vascular access and the use of surveillance techniques, all haemodialysis centres in The Netherlands received a questionnaire regarding the types of vascular accesses and surveillance techniques used in their department on 31 December, 1996. The results were related to a comparable study done in 1987, shown between brackets. RESULTS: The response of the haemodialysis staff was 96%, of the vascular surgeons this was 91%. Sixty-two per cent (70%) of the patients had Brescia-Cimino fistulas, 21% (13%) Polytetrafluoroethylene (PTFE) graft fistulas, 17% (17%) other vascular accesses. Scheduled surveillance for stenosis detection was done by recirculation measurements in 6%, venous pressure measurements in 31%, Duplex scanning in 11% and angiography in 11% of the centres. When access problems occurred, 79% of the physicians performed recirculation measurements, 38% venous pressure measurements, 79% Duplex scanning and 100% angiography. In 46% of the centres PTA was done occasionally, and in 46% routinely for the treatment of stenotic complications in arteriovenous fistulas. CONCLUSIONS: The use of PTFE grafts and other types of vascular accesses has increased at the expense of BC fistulas. Recirculation and venous pressure measurements are primarily done when problems occur and not according to a standard surveillance schedule. For visualization of failing fistulas, 79% of the centres uses Duplex ultrasound analysis and 100% angiography. The popularity of PTA has increased from 46 to 92% of the centres.
Adolescent↗
Motor denervation induces altered muscle fibre type densities and atrophy in a rat model of neuropathic pain.
Loose ligation of a sciatic nerve in rats (chronic constriction injury; CCI) provokes sensory, autonomic, and motor disturbances like those observed in humans with partial peripheral nerve injury. So far, it is unknown whether these motor disturbances result from (mechanical) allodynia or from damage to the motor neuron. These considerations prompted us to assess, in CCI rats, the density of motor axons in both the ligated sciatic nerve and the ipsilateral femoral nerve. To this end, we determined the number of cholinesterase positive fibres. It has been demonstrated previously that muscle fibre type density may be used as a measure of motor denervation and/or hypokinesia. Therefore, the myofibrillar ATPase reaction was employed to assess fibre type density in biopsies obtained from the lateral gastrocnemius muscle (innervated by sciatic nerve) and rectus femoris muscle (innervated by femoral nerve). We observed axonal degeneration of motor fibres within the loosely ligated sciatic nerve, both at an intermediate (day 21) and at a late stage (day 90) after nerve injury. The reduction in the number of motor nerve fibres was more pronounced distal to the site of the ligatures than proximal. A (less pronounced) reduction of motor fibres was observed in the ipsilateral (non-ligated) femoral nerve. In line with these findings, we observed altered fibre type densities in muscle tissue innervated by the ligated sciatic nerve as well as the non-ligated femoral nerve indicative of motor denervation rather than hypokinesia. The findings of this study suggest that the motor disorder induced by partial nerve injury involves degeneration of motor nerve fibres not only within the primarily affected nerve but also within adjacent large peripheral nerves. This spread outside the territory of the primarily affected nerve suggests degeneration of motor neurons at the level of the central nervous system.
Acetylcholinesterase↗
Effects of surgical sympathectomy on skin blood flow in a rat model of chronic limb ischemia.
The role of lumbar sympathectomy in the treatment of limb ischemia secondary to arteriosclerosis obliterans has been controversial. Increased temperature and rubor of the skin, which usually follow sympathectomy, have generally been interpreted as indicative of improved nutritive skin blood flow. However, the existence of a (nonnutritive) thermoregulatory level of skin microcirculation makes such an extrapolation questionable. We investigated the total (mainly thermoregulatory) skin blood flow (TSBF) in the hindlimb of 15 male Lewis rats by means of laser Doppler flowmetry and the nutritive skin blood flow (NSBF) by means of capillary microscopy (red blood cell velocity). Transcutaneous oximetry was used to assess skin oxygenation (SO). Measurements were performed before and 2 and 28 days after ligation of the common iliac and iliolumbar artery. Subsequently, either a surgical resection of the sympathetic chain (L2-L6) was performed or a sham operation. Measurements were repeated 2 and 28 days later. For the group of 15 rats as a whole, TSBF (p < 0.05), NSBF (p < 0.05), and SO (p < 0.05) were found to be drastically reduced at day 2 after litigation compared to preligation values. This reduction partially recovered during the following weeks. TSBF (p < 0.05) and NSBF (p < 0.05), however were still reduced at day 28 after ligation compared to preligation values, whereas the SO at this time tended to be lower (p = 0.11). In the sympathectomy group the TSBF was found to be increased at day 2 (p < 0.05) and day 28 (p < 0.05) after sympathectomy, both compared to values obtained at day 28 after ligation. Sympathectomy did not have an effect on NSFB and SO. The sham procedure had no effect on the TSBF, NSBF, or SO. These results indicate that in case of lower limb ischemia, sympathectomy improves skin blood flow at the thermoregulatory but not the nutritive level of skin microcirculation. This may be related to the fact that the thermoregulatory vessels are mainly sympathetically controlled, whereas the nutritive capillaries are mainly controlled by local (nonneural) factors.
Animals↗
Wall shear stress in the human common carotid artery as function of age and gender.
OBJECTIVES: It has been postulated that in the arterial system mean wall shear stress is maintained at a constant value. The present study was performed to investigate the level of wall shear stress in the common carotid artery (CCA) as function of age and possible interactions between diameter and storage capacity, defined as the absolute area change per heart beat, with mean wall shear stress. METHODS: Wall shear stress (wall shear rate multiplied by whole blood viscosity) was assessed in the right CCA of 111 presumed healthy male (n = 56) and female (n = 55) volunteers, varying in age between 10 and 60 years. Wall shear rate was measured with a high resolution ultrasound system. Simultaneously, arterial diameter and storage capacity were determined. Whole blood viscosity was calculated from haematocrit, plasma viscosity and shear rate. RESULTS: From the second to the sixth age decade peak wall shear stress was significantly higher in males than in females and decreased from 4.3 Pa to 2.6 Pa (r = -0.56, p < 0.001) in males and from 3.3 Pa to 2.5 Pa (r = -0.54, p < 0.001) in females. Mean wall shear stress tended to decrease from 1.5 Pa to 1.2 Pa (r = -0.26, p = 0.057) in males and decreased significantly from 1.3 Pa to 1.1 Pa (r = -0.30, p = 0.021) in females. No significant difference in mean wall shear stress was found between males and females in any age decade. The diameter of the CCA increased significantly in both males (r = 0.26, p < 0.05) and females (r = 0.40, p < 0.003). Storage capacity decreased significantly in both sexes (males: r = -0.63, p < 0.001; females: r = -0.68, p < 0.001). CONCLUSIONS: These observations suggest that the reduction in mean wall shear stress with age results from the concomitant increase in diameter in an attempt of the arterial system to limit the reduction in storage capacity of the arterial system with increasing age.
Adolescent↗
Complications of standard elective abdominal aortic aneurysm repair.
OBJECTIVE: To evaluate complications of standard elective repair of infrarenal abdominal aortic aneurysms. DESIGN: Prospective multicentre study. MATERIALS: Two-hundred and ninety-one consecutive patients undergoing standard elective surgery for an infrarenal aortic aneurysm. METHODS: Recording adverse events according to the recommendations of the Ad Hoc Committee on Reporting Standards. RESULTS: Seventy-five patients (26%) experienced some complication following elective aortic aneurysm surgery. Twenty-two patients had a mild complication (7.6%, 95% C.I. 4.8-11.2%), 27 a moderate (9.3%, 95% C.I. 6.2-13.2%) and 26 patients had a severe and/or fatal complication (8.9%, 95% C.I. 5.9-12.8%). The in-hospital mortality was 4.1% (12 patients, 95% C.I. 2.2-7.1%). Cardiac failure was the commonest primary cause for death (58%). Twenty-two per cent of the patients had a non-fatal complication: the most frequent being pulmonary (10%) and cardiac (10%). Patients with a history of cardiac events had a five times higher risk of a fatal outcome (95% C.I. 1.1-24.0) and a two and a half times higher risk of any severe fatal or non-fatal complication (95% C.I. 1.0-6.5). Other risk factors were advancing age and the presence of pulmonary disease. CONCLUSIONS: In addition to mortality, morbidity figures of standard aneurysm operations are important, as well as associated risk factors. This is especially true when evaluating early repair of small aneurysms and new endovascular techniques.
Age Factors↗
Neurogenic inflammation in an animal model of neuropathic pain.
Loose ligation of a rat sciatic nerve (chronic constriction injury (CCI) model) provokes signs and symptoms like those observed in reflex sympathetic dystrophy (RSD) patients. Primary afferent nociceptive C-fibers seem to be involved in an afferent orthodromic as well as in an efferent antidromic manner. In this study we hypothesize that consequent to development of antidromic impulses in C-nociceptive afferents, neuropeptides released from peripheral endings of these fibers, increase skin blood flow (SBF), vascular permeability, and tissue accumulation of polymorphonuclear leukocytes (PMNs). Collectively, these phenomena have been referred to as neurogenic inflammation. To investigate the presence of neurogenic inflammation in the CCI-model, we assessed skin blood flow (SBF) as well as the level of edema and accumulation of PMNs in muscle tissue obtained from the affected hindpaw. SBF was measured, by means of laser Doppler flowmetry, before ligation as well as at day 4 after ligation. At day 4, SBF measurements were performed before and after abolition of the capability of C-fibers to mediate a vasodilator response. To this end, capsaicin was applied perineurally. Increased vascular permeability was inferred from the level of edema of muscle tissue as determined by assessment of wet/dry weight ratios of muscle biopsies. PMN accumulation was investigated by enzymatic detection of myeloperoxidase (MPO) activity in muscle biopsies. Compared with preligation values, at day 4 SBF was increased more than twofold (p < 0.05). The latter response was annihilated by capsaicin application. Compared with sham operated controls, wet/dry ratios were higher in the ligated animals (1.104 vs. 1.068; p < 0.05). Likewise, when compared with sham operated controls, MPO activity was found to be increased in the ligated hindpaw (Optic Density 0.15 vs. 0.89; p < 0.001). In conclusion, the findings of this study indicate that loose ligation of a sciatic nerve induces an inflammatory response in the ipsilateral hindpaw, which most likely is mediated by release of neuropeptides from the peripheral endings of antidromically acting nociceptive C-fibres.
Animals↗
Penetration of ceftazidime into bone from severely ischaemic limbs.
Ten patients received 2000 mg of ceftazidime intravenously before undergoing lower-extremity amputation for ischaemia. Bone and plasma concentrations were determined by HPLC. The bone concentrations were corrected for blood contamination. In all but one sample ceftazidime was detectable. The median concentration in the midfoot, 4.8 microg/g (range 1.2-11.4 microg/g), was higher than the median concentration in the forefoot, 3.1 microg/g (range 0.8-15.7 microg/g) (P <0.05). In the majority (>90%) of bone samples taken from sites with gangrenous skin the ceftazidime concentration was >1.8 mg/kg bone. The present data indicate that ceftazidime penetrates into bone of severely ischaemic limbs.
Aged↗
Peripheral vascular tree stenoses: detection with subtracted and nonsubtracted MR angiography.
PURPOSE: To compare subtracted and nonsubtracted gadolinium-enhanced magnetic resonance (MR) angiography and cardiac-synchronized time-of-flight MR angiography for help in detecting pelvic-region stenoses. MATERIALS AND METHODS: Twenty-eight patients with intermittent claudication underwent MR angiography with a 1.5-T system; two-dimensional cardiac-synchronized time-of-flight MR angiograms and three-dimensional MR angiograms (without and with gadolinium enhancement) were obtained. Subtracted images were obtained by subtracting unenhanced data from enhanced data of identical volumes, and maximum intensity projection images were constructed, which two observers independently evaluated in blinded fashion, with conventional angiographic results as the reference standard. RESULTS: Sensitivity and specificity for grading of hemodynamically significant stenoses (> or = 50% lumen reduction) on subtracted MR angiograms were 94% and 93%, respectively. Sensitivity of subtracted images was significantly higher compared with that of time-of-flight images (P < .05) but not with that of nonsubtracted images. Contrast-to-noise ratio on subtracted images was significantly higher compared with that on nonsubtracted images (P < .05) but not with that on time-of-flight images. There was good correlation between stenosis length measurements on gadolinium-enhanced MR angiograms and those on conventional angiograms. CONCLUSION: Subtracted MR angiography is superior to cardiac-synchronized time-of-flight MR angiography for imaging of iliac and upper femoral arteries and provides higher contrast-to-noise ratio, fewer artifacts, and easier image interpretability than nonsubtracted MR angiography.
Angiography↗
Peripheral vascular tree stenoses: evaluation with moving-bed infusion-tracking MR angiography.
PURPOSE: To evaluate a magnetic resonance (MR) angiographic technique for imaging of the peripheral arteries with gadolinium enhancement. MATERIALS AND METHODS: Moving-bed infusion-tracking MR angiograms were obtained in 15 healthy volunteers and in 28 patients with intermittent claudication before and during slow infusion of contrast material. Lower- and upper-leg and pelvic regions were imaged. Unenhanced images were subtracted from gadolinium-enhanced images, and maximum intensity projection images were generated. Image quality was evaluated subjectively and objectively, and maximum intensity projection images were compared with conventional angiograms, which served as the standard of reference. RESULTS: Moving-bed infusion-tracking MR angiography proved to be a robust technique, and image quality on maximum intensity projection images was comparable with that on conventional angiograms. Sensitivity and specificity for grading hemodynamically significant stenoses were 93% and 98%, respectively, with excellent interobserver agreement. CONCLUSION: Moving-bed infusion-tracking MR angiography can be used to image all peripheral arteries in 4 minutes by using a small amount of contrast material and a conventional 1.5-T MR imager.
Constriction, Pathologic↗