Critical role of P-selectin-dependent leukocyte recruitment in endotoxin-induced intestinal barrier dysfunction in mice.

OBJECTIVE: To define the importance of leukocyte recruitment in endotoxin-induced gut permeability. MATERIALS AND METHODS: 31 male C57BL/6 mice were challenged with lipopolysaccharide (LPS). Ileal permeability was measured in Ussing chambers and leukocyte-endothelium interactions studied with intravital fluorescence microscopy after 18 h. RESULTS: LPS caused a clear-cut increase in leukocyte accumulation and intestinal permeability. Immunoneutralisation of P-selectin not only reduced leukocyte recruitment significantly (54 % reduction) but also abolished endotoxin-induced intestinal leakage. Intestinal levels of pro-inflammatory chemokines increased markedly in response to LPS but were not influenced by inhibition of P-selectin in vivo. CONCLUSION: The present study shows not only that endotoxin-induced leukocyte recruitment is mediated by P-selectin but also that sepsis-associated intestinal leakage in the gut is largely regulated by leukocyte accumulation. Thus, our novel data demonstrate a critical link between P-selectin-dependent leukocyte recruitment and gut barrier failure in endotoxemia.

Systemic interleukin-6 response to colorectal surgery originates from the bowel.

BACKGROUND: Surgical trauma evokes a systemic cytokine response which is enhanced in patients with colorectal cancer. The aim of this study was to locate the origin of the systemic cytokine response to colorectal surgery. METHODS: The concentrations of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) were analysed in systemic and mesenteric venous blood in 12 patients operated on with colorectal resections due to cancer or benign lesions. Immunohistochemical staining and analysis of tissue concentrations of IL-6 and TNF-alpha in homogenates from tumours and benign specimens were performed. RESULTS: Mesenteric venous blood contained higher concentrations of IL-6 compared to systemic venous blood after resection, but not before. Tissue concentration of IL-6 was higher in the tumours compared to the benign specimens and immunohistochemistry revealed an abundance of IL-6 and TNF-alpha in malignant epithelium compared to benign mucosa. CONCLUSION: The higher concentration of IL-6 in venous blood from the mesenterium of the resected colonic segment compared to systemic levels, indicates that the bowel is the source of the IL-6 response to surgical trauma in colorectal surgery.

hMLH1, hMSH2 and hMSH6 mutations in hereditary non-polyposis colorectal cancer families from southern Sweden.

We have screened 17 Southern Sweden individuals/families with suspected hereditary non-polyposis colorectal cancer (HNPCC) for mutations in the DNA-mismatch repair genes hMLH1, hMSH2 and hMSH6 using denaturing gradient gel electrophoresis, protein truncation test and direct DNA sequencing. The families were selected on the basis of a family history of HNPCC-related tumors or the occurrence of metachronous colorectal cancer/endometrial cancer at young age in an individual with a weak family history of cancer. Furthermore, we required that tumor tissue from at least one individual in the family had to display microsatellite instability. We identified germ-line mutations in 9 individuals from 8 families. Five families had mutations in hMLH1, 4 of which were splice site mutations, 2 had frameshift mutations in hMSH2 and 1 patient with metachronous endometrial and rectal cancer but with a weak family history of cancer had a nonsense mutation in hMSH6. Our results present novel germ-line DNA-repair gene mutations, one of these in hMSH6, and demonstrate the diversified mutation spectrum in Sweden, where no founder mutation has so far been identified.

Improved reliability of ultrasonic surveillance of abdominal aortic aneurysms.

OBJECTIVES: Small abdominal aortic aneurysms (AAA) are usually managed conservatively by serial ultrasound examinations to assess size. The development of the size of the AAA will determine whether the patient is a candidate for surgery. The precision of measurement is therefore of considerable importance. The aim of this study was to evaluate the accuracy and the reproducibility of a newly developed echo-tracking ultrasonic system in the size evaluation of AAA. DESIGN: Prospective study at a University Hospital. MATERIAL AND METHODS: An echo-tracking ultrasound system with a 3.5 MHz transducer was used in 54 patients with AAA. Thirty-six patients had repeated measurements by one technician to evaluate the intra-observer variability. In another 18 patients with aortic dilatation/AAA, the measurements were repeated by a second technician in a blinded fashion with calculation of inter-observer variability. The reproducibility was evaluated both using linear regression and plots according to the method described by Bland and Altman. RESULTS: The mean diameter of the aorta was 37 mm (range 21-51 mm). The coefficient of correlation of repetitive measurements with one observer was r = 0.99 and with two observers r = 0.99. The intra-observer variability was 0.78 mm (S.D.) and the inter-observer variability 0.93 mm (S.D.). The intra- and inter-observer coefficient of variation (CV) was 2-3%. CONCLUSIONS: The newly developed echo-tracking ultrasonography seems at present to be the most accurate and reliable method to follow the diameter of an abdominal aortic aneurysm detecting relevant changes in the diameter exceeding 2 mm (2 S.D.). Thus it fulfils the requirements both for follow-up of conservatively managed AAAs and endovascularly treated aneurysms.

Are self-expanding stents superior to balloon-expanded in dilating aortas? An experimental study in pigs.

OBJECTIVE: To study the stent/vessel interaction and distensibility following the natural increase in vascular diameter using self-expanding and balloon-expanded stents. DESIGN: Open experimental study. SETTING: Animal laboratory, university hospital. MATERIALS AND METHODS: Eight Palmaz (P) and eight Gianturco (G) stents were transluminally placed in the infrarenal aortas of 16 pigs. Pulsatile diameter changes above, at and below the stents were non-invasively monitored with an ultrasound phase-locked echo-tracking system before and immediately after stenting and at 4 and 18 weeks. Blood pressure was registered intra-arterially and stiffness (beta) was calculated. Intravascular ultrasound (IVUS) was performed at 18 weeks. RESULTS: Median weight increased from 20 kg (19-26) to 93 kg (62-130). Diameter of the aorta increased 60%. In group P no pulsatile diameter change could be measured at the stent (beta = infinity). In group G stenting increased stiffness from beta 20.7 (9.2) to 43.2 (8.0) (p < 0.05). After 18 weeks stiffness returned to beta 20.1 (12.4). Expanded, median diameter of the P stents was 7.4 (0.8) mm, not increasing after 18 weeks. Initial diameter of the G stents was 7.8 (1.0) mm, increasing 56% to 12.2 (2.3) mm (p < 0.05). IVUS revealed the G stents to be well attached to the vascular wall, but five P stents were detached within half of the circumference. CONCLUSION: Self-expanding stents follow the pulsatile diameter change of the vessel wall, not adversely affecting distensibility after 18 weeks. They show good attachment despite 56% dilation. In contrast, the balloon-expanded stents do not show pulsatile movement and may detach during vessel diameter increase. This may be of importance when choosing stents for endovascular treatment of abdominal aortic aneurysms.

Regional differences in mechanical properties between major arteries--an experimental study in sheep.

PURPOSE: To study possible differences in mechanical properties between central (abdominal aorta) and more peripheral (common carotid and common femoral) arteries validating an earlier non-invasive study in children showing that central arteries are more distensible than peripheral ones. As invasive blood pressure was needed, but ethically impossible to obtain in children in an experimental setting, an animal model was chosen. DESIGN: Open experimental study. SETTING: Animal laboratory at university hospital. MATERIAL AND METHODS: The pulsatile vessel wall movements of the abdominal aorta (AA), common femoral (CFA) and common carotid (CCA) artery of nine sheep were examined using an ultrasound phase-locked echo-tracking technique. Intra-arterial blood pressure was measured and pressure-diameter relations, pressure strain elastic modulus (Ep) and stiffness (beta) calculated. Distensibility was defined as the inverse of Ep and stiffness. RESULTS: The AA showed lower values for Ep and stiffness (beta) than the CFA (p = 0.002) and CCA (p = 0.006), i.e. the latter two vessels were stiffer. The pressure-diameter relations confirmed these differences and showed a non-linearity for all three vessels with increased stiffness above 70-90 mm Hg. CONCLUSION: This study on young animals supports earlier findings of differences in mechanical properties between central and more peripheral arteries seen in healthy children. As pathologies between these vessels differ, with dilatation of the abdominal aorta and occlusive disease in the more peripheral vessels, part of the explanation might be found in the mechanical properties of the healthy vessels, characterised here with the echo-tracking technique.

Diameter and compliance in the human common carotid artery--variations with age and sex.

In this study, age and sex differences in diameter and compliance of the common carotid artery (CCA) were evaluated in 119 healthy subjects with a phase-locked echo-tracking system. The diameter and pulsatile diameter changes were measured, and pressure strain elastic modulus (Ep) and stiffness (beta) were calculated and used as the inverse estimate of compliance. The carotid diameter increased more rapidly in males and was larger than in females from 25 years of age. The relative diameter change was equal in both sexes, and decreased from 12% to 14% in younger subjects to approximately 5% in elderly subjects. Compliance decreased almost linearly and in parallel in males and females up to 45 years of age. Between 45 and 60 years the decrease was more marked in females than in males, whereas it was by far more marked in males between 60 and 70 years of age.

Differences in mechanical properties of the common carotid artery and abdominal aorta in healthy males.

PURPOSE: Vascular disease is differentiated throughout the vascular regions, with central arteries more prone to dilation and with peripheral arteries more prone to occlusive disease. In this study we investigated the diameter and compliance in the common carotid artery and abdominal aorta in healthy males at varying ages to assess potential differences in the aging process. METHODS: An ultrasound phase-locked echo-tracking system was used to determine differences in diameter and pulsatile diameter changes of the common carotid artery and abdominal aorta in 56 healthy Caucasian males ages 10 to 74 years. Pressure strain elastic modulus (Ep) and stiffness (beta) were calculated from diameter, pulsatile diameter change, and blood pressure obtained by the auscultatory method. Compliance was defined as the inverse of Ep and stiffness. RESULTS: The diameter of both common carotid artery and abdominal aorta increases not only when a person is a child, but also when they are between 25 and 70 years old. The dilation in adults seems to be more accentuated in the abdominal aorta (27%) than in the common carotid artery (17%). Ep and stiffness (beta) are higher in the common carotid artery when a person is 10 years of age (p < 0.01 and 0.05). However, during aging, Ep and stiffness (beta) increase to a higher extent in the aorta than in the common carotid artery, with a significantly higher Ep and stiffness (beta) in the aorta when a person is 45 years and older (45 years: p < 0.05 and p = NS; 60 years: p < 0.001 and p < 0.001; 70 years: p < 0.01 and p < 0.01). CONCLUSIONS: This investigation demonstrates regional differences in diameter change and compliance in the common carotid artery and abdominal aorta and implies that the abdominal aorta is more prone to degenerative changes than the common carotid artery. This may be one etiologic factor for the regional differences in vascular disease.

Non-invasive measurement of pulsatile vessel diameter change and elastic properties in human arteries: a methodological study.

A recently developed ultrasound phase-locked echo-tracking system makes it possible to measure non-invasive pulsatile vessel diameter changes, and, in combination with blood-pressure measurement, to calculate pressure strain elastic modulus (Ep) and stiffness (beta). The reproducibility in measurements of pulsatile diameter changes with this system was evaluated. Also the precision of indirect blood-pressure measurements, as compared to the simultaneously measured intra-arterial blood pressure was tested. The resulting reproducibility in pressure strain elastic modulus (Ep) and stiffness (beta) was evaluated. Intra-observer variabilities in measuring pulsatile diameter changes were 16% for the abdominal aorta, 10% for the common carotid artery, and 15% for the common femoral artery, respectively. Intra-observer variabilities for Ep and beta were 21% for both in the abdominal aorta, 17% for both in the common carotid artery, and 18% for both in the common femoral artery, respectively. There were only small differences in indirect and direct measurement of systolic blood pressure, whereas indirect blood pressure measurement systematically overestimated the diastolic blood pressure, on average by 20%. The variabilities in indirect blood pressure measurements were 2% for the systolic and 3% for the diastolic blood pressure, respectively. Inter-observer variability in the investigation of the common carotid artery was 10% for the pulsatile diameter changes, and 21% and 23% for Ep and beta, respectively. Thus, the echo-tracking system represents a reliable system for estimation of pressure strain elastic modulus and stiffness. However, Ep and beta are systematically underestimated by 25-30%, when used in combination with indirect blood pressure measurements.

Extraanatomic vascular reconstruction in patients with aorto-iliac arteriosclerosis.

During an 11-year period 117 extraanatomic reconstructions were made for aorto-iliac arteriosclerosis; 36 axillofemoral and 81 femorofemoral crossover bypasses. The patients were old and had several factors making them poor risks for surgery. Axillofemoral grafts were more often used in patients with malignant disease. Postoperative mortality was 10% without difference between the two types of reconstruction. Both early and late complications were significantly more frequent in patients with axillofemoral bypass. Reoperations for occlusion and symptoms from the donor side also were significantly more common among axillofemoral patients. Life table analysis showed a higher survival and patency rate among patients with crossover grafts.