Bond Behavior of Steel Cords Embedded in Inorganic Mortars

This paper investigates the bond behavior of steel cords embedded in inorganic matrices. A series of pull-out tests were carried out on individual galvanized steel cords embedded in either a cementitious or lime-based mortar matrix and the corresponding bond-slip relationships were derived. The quality of bond between cord and mortar was found to be critically affected by the workability of the mortar and its ability to create adequate composite action along the entire embedment length of the cord. The more workable lime-based mortar was found to guarantee a better interaction with the steel cord, in terms of initial bond stiffness, maximum bond strength, and post-peak behavior. The experimentally derived bond–slip relationships were subsequently integrated in a 3D non-linear finite element framework and used to determine the constitutive relationship of a surface-based cohesive contact between cord and mortar. The cohesive bond behavior was used to conduct a series of parametric studies on cords embedded in a lime-based mortar and examine the stress development within specimens with cords of different embedment lengths and subjected to different loading conditions (i.e., pull-out and direct tension). The active ‘Stress Transfer Zone’ was found to be about 125 mm, while an ‘Effective Transfer Radius’ of approximately 3.5–4 mm was identified. The numerical investigation implemented in this paper enabled one to study key interaction properties of steel reinforced grouts and can assist the design of more effective strengthening solutions.     

Surgical Management of Craniovertebral Junction Schwannomas: A Systematic Review

Background: Craniovertebral junction (CVJ) schwannomas are rare, with surgery and stereotactic radiosurgery (SRS) being effective yet challenging options. We systematically reviewed the literature on CVJ schwannomas. Methods: PubMed, Scopus, Web-of-Science, and Cochrane were searched following the PRISMA statement to include studies reporting CVJ schwannomas. Clinical features, management, and outcomes were analyzed. Results: We collected 353 patients from 101 included articles. Presenting symptoms were mostly neck pain (30.3%) and headache (26.3%), with most cranial neuropathies involving the XII (31.2%) and X (24.4%) nerves. Most tumors originated from C2 (30.9%) and XII (29.4%) nerves, being extracranial (45.1%) and intradural-extradural (44.2%). Erosion of C1–C2 vertebrae (37.1%), the hypoglossal canal (28.3%), and/or jugular foramen (20.1%) were noted. All tumors were operated, preferably with the retrosigmoid approach (36.5%), with the far-lateral approach (29.7%) or with the posterior approach and cervical laminectomy (26.9%), far-lateral approaches (14.2%), or suboccipital craniotomy with concurrent cervical laminectomy (14.2%). Complete tumor resection was obtained most frequently (61.5%). Adjuvant post-surgery stereotactic radiosurgery was delivered in 5.9% patients. Median follow-up was 27 months (range, 12–252). Symptom improvement was noted in 88.1% of cases, and cranial neuropathies showed improvement in 10.2%. Post-surgical complications occurred in 83 patients (23.5%), mostly dysphagia (7.4%), new cranial neuropathies (6.2%), and cerebrospinal fluid leak (5.9%). A total of 16 patients (4.5%) had tumor recurrence and 7 died (2%), with median overall survival of 2.7 months (range, 0.1–252). Conclusions: Microsurgical resection is safe and effective for CVJ schwannomas. Data on SRS efficacy and indications are still lacking, and its role deserves further evaluation.     

Occult lung infarction may induce false interpretation of 18F-FDG PET in primary staging of pulmonary malignancies

Purpose The aim of the present report is to describe abnormal ¹⁸F-fluorodeoxyglucose (FDG) accumulation patterns in the pleura and lung parenchyma in a group of lung cancer patients in whom lung infarction was present at the time of positron emission tomography (PET).Methods Between November 2002 and December 2003, a total of 145 patients (102 males, 43 females; age range 38–85 years) were subjected to whole-body FDG PET for initial staging (n=117) or restaging (n=11) of lung cancer or for evaluation of solitary pulmonary nodules (n=17). Of these patients, 24 displayed abnormal FDG accumulation in the lung parenchyma that was not consistent with the primary lesion under investigation (ipsilateral n=12, contralateral n=9 or bilateral n=3). Without correlative imaging, this additional FDG uptake would have been considered indeterminate in differential diagnosis.Results Of the 24 patients who were identified as having such lesions, six harboured secondary tumour nodules diagnosed as metastases, while in three the diagnosis of a synchronous second primary lung tumour was established. Additionally, nine patients were identified as having post-stenotic pneumonia and/or atelectasis (n=6) or granulomatous lung disease (n=3). In the remaining six (4% of all patients), a diagnosis of recent pulmonary embolism that topographically matched the additional FDG accumulation (SUV_max range 1.4–8.6, mean 3.9) was made. Four of these six patients were known to have pulmonary embolism, and hence false positive interpretation was avoided by correlating the PET findings with those of the pre-existing diagnostic work-up. The remaining two patients were harbouring small occult infarctions that mimicked satellite nodules in the lung periphery. Based on histopathological results, the abnormal FDG accumulation in these two patients was attributed to the inflammatory reaction and tissue repair associated with the pathological cascade of pulmonary embolism.Conclusion In patients with pulmonary malignancies, synchronous lung infarction may induce pathological FDG accumulation that can mimic active tumour manifestations. Identifying this potential pitfall may allow avoidance of false positive FDG PET interpretation.     

Recombinant activated factor VII decreases bleeding without increasing arterial thrombosis in rabbits

PURPOSE: To compare the effects of recombinant activated factor VII (rFVIIa) and platelet-rich plasma (PRP) in an experimental model of bleeding and arterial thrombosis. METHODS: The Folts model was used in 60 rabbits. After anesthesia, the carotid artery was exposed and a 75% stenosis was induced. A compression injury of the artery triggered a series of cyclic flow reductions (CFRs). After counting baseline CFRs, animals were assigned randomly to one of four groups (n = 15 in each): control, PRP, rFVIIa and placebo. Control animals received 10 mL.kg(-1) of saline while 10 mL.kg(-1) of a hydroxyethyl starch solution (200,000/6%/0.5) were infused in the three other groups. CFRs were measured again, followed by treatment with PRP, rFVIIa or placebo and by a final measurement of CFRs. At the end of each observation period, an ear immersion bleeding time (BT) was measured and a blood sample was drawn for the evaluation of hematological variables. Microvascular bleeding was evaluated at the end of the experiment in grams of blood shed from liver and spleen sections. Results are presented as median (range). RESULTS: rFVIIa shortened the BT and decreased microvascular bleeding as compared with placebo [60 (35-100) sec vs 110 (50-140) sec, P = 0.0019 and 9 (4-24) g vs 17 (5-28) g, P = 0.002, respectively]. rFVIIa did not increase CFRs [3(0-9) vs |(0-5), P = 0.11]. CONCLUSION: rFVIIa led to a decrease in BT and microvascular bleeding but did not significantly affect arterial thrombosis in rabbits.     

Dynamic contrast-enhanced ultrasound with carbon dioxide microbubbles as adjunct to arteriography of liver tumors

Purpose The goal of the study is to evaluate utility of contrast enhanced ultrasound (US) with carbon dioxide microbubbles in evaluation of hepatic lesions.Methods Twenty eight patients with single or multiple t hepatic lesions (11 hepatocellular carcinoma, 8 hemangiomas, 5 metastases, 1 adenoma, 1 focal nodular hyperplasia, 2 regenerative nodules) were examined. US exam was performed during intraarterial injection of 10 ml of CO₂ through the same catheter employed for liver arteriography. The US exam was videotaped in its salient phases. Characteristics of enhancement were evaluated and correlated with histological findings or patient follow up.Results Sonographic angiography clearly demonstrated vascularization of the lesions. Hepatocellular carcinoma, hemangioma, metastases, focal nodular hyperplasia, and regenerative nodules had very characteristic patterns. The injection of CO₂ allowed detection of small additional nodules.Conclusion Sonographic angiography can improve characterization and staging of hepatic tumors. Low cost and the simplicity of the technique should encourage further experimentation.     

Relation between long-term steroid treatment after heart transplantation, hypofibrinolysis and myocardial microthrombi generation.

BACKGROUND: Thrombotic complications and transplant coronary artery disease are among the main causes of morbidity and mortality after heart transplantation. A thrombophilic state has been described in transplant recipients, and correlated to immunosuppressive therapy with cyclosporine A or azathioprine, whereas the prothrombotic effects of steroids, even though always given, have never been duly considered. A reduced fibrinolytic capacity due to high levels of PAI-1, the most important inhibitor of plasminogen activators, was suggested to play a role in the development of cardiovascular diseases and transplant coronary artery disease. A severe hypofibrinolytic state secondary to PAI-1 increase has been found in patients with Cushing's disease, and in hypercorticism secondary to long-term steroid treatment after renal transplantation. METHODS: We evaluated plasma clotting and fibrinolytic behaviors in 2 groups of heart transplant patients treated with (26 cases) or without (23 cases) steroids together with cyclosporine A and azathioprine. Twenty-five healthy subjects were studied as normal controls. The following tests were assayed at least 1 year after transplantation: fibrinogen, factor VIII coagulant activity, von Willebrand factor antigen, euglobulin lysis time, tissue plasminogen activator antigen and activity, PAI-1 antigen and activity. In addition, the presence of cardiac microthrombi was evaluated on 2 endomyocardial biopsy specimens obtained in each patient both on day 7 after heart transplantation (first control) and usually 1 year or more later (last control). RESULTS: Plasma levels of fibrinogen, factor VIII and von Willebrand factor were significantly higher in both groups of patients than in normal controls. Fibrinolytic activity was significantly reduced in transplant patients treated with steroids, compared with steroid-free patients and normal controls. In steroid-treated heart transplant recipients, the hypofibrinolytic state was due to a significant and pathological increase in PAI-1 antigen and activity levels. The fibrinolytic impairment was more evident in patients transplanted for ischemic heart disease and treated with steroids than in patients with previous dilated cardiomyopathy and treated either with or without steroids. Myocardial microthrombi were found in 2/49 cases at the first biopsy control, and in 12/49 cases at the last biopsy control after transplantation. This different prevalence was statistically significant (chi2 = 8.33, p = .003). Plasma PAI-1 activity was significantly higher and, as a consequence, euglobulin lysis time was more prolonged in microthrombi-positive patients than in microthrombi-negative ones. Among the 12 transplant recipients who developed cardiac microthrombi, 7 patients were treated with steroids and showed higher PAI-1 levels and more reduced fibrinolytic activity than the 5 steroid-free patients. CONCLUSIONS: Our data confirm the prothrombotic state induced by long-term steroid treatment, characterized by an increase in PAI-1 levels and secondary impairment of fibrinolytic capacity. In heart transplant patients, steroid-related hypofibrinolysis might constitute a further risk factor for transplant coronary artery disease.     

Plasma Cholecystokinin Levels after Vertical Banded Gastroplasty: Effects of an Acidified Meal

Background: Although cholecystokinin (CCK) is involved in the short-term regulation of satiety, it has not been investigated in obese patients subjected to bariatric restrictive operations. Methods: 8 morbidly obese patients (BMI 49.1 ± 6.9), 7F and 1M, were investigated before and after vertical banded gastroplasty (VBG). 6 healthy lean volunteers served as the control group. CCK was determined (RIA) after an overnight fast and after the administration of an acidified (pH 3) liquid meal. Blood samples were taken 45 min before the meal, 5 min after it and then every 30 min for 3 hours. Results: There were no differences between groups in basal CCK levels. However, the peak of CCK after the meal was significantly higher (P <0.01) in obese patients after VBG (24.9 ± 18 pmol/l) than before VBG (9.8 ± 6.7 pmol/l) and when compared with the control group (8.0 ± 6.3 pmol/l).The time needed to reach the peak was longer in healthy volunteers (105 ± 24.9 min) than in obese patients before VBG (45 ± 40 min) and after VBG (7.5± 12 min) (P<0.01). Conclusions: VBG increases the peak of CCK secretion and shortens the time to reach it. These changes could contribute to the satiety effects of gastric restrictive operations.