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At least 217 records · Page 12Linked to original sources

Retardation of organo-bromides in a fractured chalk aquitard.

This study investigates the mechanisms controlling the distribution of 3-bromo-2,2-bis(bromomethyl)propanol (TBNPA) and 2,2-bis(bromomethyl)propan-1,3-diol (DBNPG) in a fractured chalk aquitard. An extensive monitoring program showed a systematic decrease in the TBNPA/DBNPG ratio with distance from the contamination source. Sorption of TBNPA on the white and/or gray chalks comprising the aquitard is approximately one order of magnitude greater than that of DBNPG. This results in more efficient removal of TBNPA from the fracture into the porous matrix and thus decreases the TBNPA/DBNPG ratio in the fracture water. Mathematical modeling of solute transport in the fracture domain illustrates the probable importance of sorption in controlling the spatial variation in TBNPA and DBNPG ratio.

Adsorption↗

Protruding aortic arch thrombus: treatment with minimally invasive surgical approach.

BACKGROUND: Protruding aortic arch thrombus is associated clinically with life-threatening emboli. Definitive treatment for aortic arch thrombus removal has demanded complicated vascular surgical procedures, with high morbidity and mortality. METHODS AND RESULTS: Transesophageal echocardiography (TEE) enabled diagnosis of a protruding thrombus at the aortic arch in 5 patients, and a simultaneous lesion in the descending aorta in 1 patient. Four patients had visceral emboli, coinciding with peripheral emboli in 2 patients, and the fifth patient had peripheral and cerebral emboli. One patient had had ischemic stroke and femoral emboli a few months previously. Mean patient age was 51 years. None had clinical evidence of coronary or peripheral atherosclerotic occlusive disease. Risk factors included hypertension (n = 2), smoking (n = 4), and preexisting thrombophilia (n = 4). Five patients underwent TEE-guided aortic balloon thrombectomy from the arch with a 34-mm occluding balloon catheter. One patient also underwent balloon thrombectomy from the descending aorta with a 14F Foley catheter. Access into the aorta was obtained through the iliac artery (n = 4) during laparotomy because of visceral ischemia or through the transfemoral approach (n = 2). Previous procedures included superior mesenteric embolectomy (n = 3), segmental bowel resection (n = 1), splenectomy (n = 1), and peripheral arterial embolectomy n = 3). Real-time intraoperative TEE enabled visualization of the protruding thrombus and assisted with maneuvering of the balloon catheter. At completion peripheral thrombectomy thrombus material was retrieved in 4 patients. Postoperatively there were no clinically proved new procedure-related visceral emboli, and all patients received anticoagulant therapy thereafter. Follow-up TEE within 2 weeks and up to 7 years revealed no recurrent aortic arch thrombus. CONCLUSIONS: TEE-guided aortic balloon thrombectomy used in 6 procedures was effectively completed without visceral or peripheral ischemic complications. It enabled removal of the life-threatening source of emboli from the proximal aorta, thereby averting the need of major aortic surgery.

Aortic Arch Syndromes↗

The effect of non-insulin dependent diabetes mellitus on uncontrolled hemorrhage in a rodent model.

OBJECTIVE: Diabetes mellitus (DM) is an independent risk factor for higher morbidity and mortality rates from trauma. We tested the null hypothesis that there would be no difference in the hemorrhage volumes and hemodynamic responses to uncontrolled hemorrhage between Zucker Diabetic Fat rats (ZDF) and euglycemic Sprague-Dawley rats (SD). METHODS: Twenty-four adult male rats (12 ZDF and 12 SD) were anesthetized with althesin via the intraperitoneal route. The femoral artery was cannulated by cut-down to monitor the heart rate (HR), mean arterial pressure (MAP) and to obtain blood samples for blood gas analysis. Twelve rats (6 ZDF and 6 SD) underwent uncontrolled hemorrhage by 50% tail amputation. Twelve rats (6 ZDF and 6 SD) served as non-hemorrhage controls. The HR, MAP, lactate (LAC), glucose levels (GL) and cumulative hemorrhage volume (CHV) were measured pre-hemorrhage and then every 15 min post-hemorrhage for 120 min. Data were reported as mean+/-S.E.M. Group comparisons were analyzed by ANOVA with repeated values; post hoc testing by Bonferroni (all tests were two-tailed, alpha = 0.05). RESULTS: Pre-hemorrhage the SD and ZDF were evenly matched for LAC, HR and MAP. CHV (cm3/100 g) was significantly (p = 0.008) greater in the ZDF (1.49+/-0.12) as compared to the SD (0.38+/-0.11). The ZDF had significantly (p < 0.001) higher LAC (7.96+/-0.61 mmol/L) than the SD (2.0+/-0.41 mmol/L). CONCLUSION: DM as compared to non-DM rats suffered a greater blood loss with a more severe lactic acidosis after a comparable uncontrolled vascular injury.

Analysis of Variance↗

Echocardiography in diagnostic assessment of peripheral arterial embolization.

In an attempt to identify a cardiac source of emboli, two-dimensional echocardiography was performed postoperatively in 42 consecutive patients with acute peripheral arterial embolism requiring urgent embolectomy. The patients were divided into four groups. Group 1 included 14 patients with chronic atrial fibrillation, among whom four cases of intracavitary thrombi were detected. Group 2 included 13 patients with acute or previous myocardial infarction, and left ventricular thrombi were detected in three. Group 3 included one patient with a prosthetic mechanical aortic valve and one with mitral valve prolapse; thrombi were not detected in either. Group 4 comprised 13 patients with no clinical evidence of a cardiac source of embolism; in one of them a large left ventricular thrombus was detected. Altogether eight intracavitary thrombi were detected (19%), and only in three (7.1%) were the results of echocardiographic examinations defined as entirely normal. A number of clinically undetected cardiac lesions, such as mitral annular calcification and aortic valve calcification, possibly associated with peripheral arterial embolism, were also detected by postoperative echocardiography. Because of the high percentage of intracavitary thrombi detected and the therapeutic implications thereof, especially if embolism recurred, it is concluded that two-dimensional echocardiographic examination should be recommended for patients with acute peripheral embolism.

Aged↗

FGF receptors ubiquitylation: dependence on tyrosine kinase activity and role in downregulation.

A crucial aspect of ligand-mediated receptor activation and shut-down is receptor internalization and degradation. Here we compared the ubiquitylation of either wild type or a K508A 'kinase-dead' mutant of fibroblast growth factor receptor 3 (FGFR3) with that of its naturally occurring overactive mutants, G380R as in achondroplasia, or K650E involved in thanatophoric dysplasia. Fibroblast growth factor receptors ubiquitylation was found to be directly proportional to their intrinsic tyrosine kinase activity, both of which could be blocked using kinase inhibitors. Despite excessive ubiquitylation, both overactive mutants failed to be efficiently degraded, even when challenged with ligand or overexpression of c-Cbl, a putative E3 ligase. We conclude that phosphorylation is essential for FGFR3 ubiquitylation, but is not sufficient to induce downregulation of its internalization resistant mutants.

Achondroplasia↗

The effect of ischemia of the dog's colon on transmural migration of bacteria and endotoxin.

The purpose of this investigation was to evaluate the effect of temporary ischemia created during the surgical preparation of the colon for resection on transmural migration of bacteria and passage of endotoxin through the ischemic wall of the canine colon. Eighteen dogs were used: in fourteen the colon was devascularized by ligating all marginal vessels. Aerobic and anaerobic cultures and washings for endotoxin assay were obtained from the surface of the bowel at intervals up to 6 hr after creating the ischemia. Peripheral and portal blood samples were also obtained at equal intervals for bacteriologic cultures and endotoxin assay. Bacterial transmural migration was examined in 10 dogs. In 6 of the dogs biologically marked bacteria were introduced into the colon via a rectal catheter before producing the ischemia. In 4 dogs radioactively labeled endotoxin was introduced into the colon in a similar fashion. In all the dogs, surface cultures, both routine and specific for the marked bacteria, were negative for the whole period of up to 6 hr after creation of ischemia. All portal and peripheral vein cultures were also negative. Transmural migration of endotoxin was investigated in 8 dogs, 4 of which served as controls and underwent a sham operation. In the 4 dogs in which the colon was devascularized endotoxin was discovered in peritoneal washings, and in portal and systemic blood samples, as early as 30 min after the preparation of the bowel was completed. In the control dogs endotoxin assays were negative throughout the experiment. In this model up to 6 hr of ischemia did not result in migration of bacteria through the ischemic wall. Endotoxin, however, entered the peritoneum and the blood very soon after producing the ischemia.

Animals↗

Reoperation. Planned and unplanned.

Reoperation is an integral part of the damage control sequence. Each type of reoperation represents an entirely different operative profile with different tactical considerations. This article discusses in detail the key decisions and techniques of planned and unplanned reoperation.

Abdomen↗

Sorption of organic contaminants in a fractured chalk formation.

Sorption capability of bedrock components from a fractured chalk province was evaluated using ametryn, phenanthrene, m-xylene, 2,4,6-tribromophenol, and 1,2-dichloroethane. Sorption isotherms for the four aromatic compounds were nonlinear on gray (unoxidized) chalk. Over the studied solution ranges, the distribution coefficient decreased by factor of 3 for phenanthrene and m-xylene, a factor 4 for ametryn, and by an order of magnitude for 2,4,6-tribromophenol. In contrast, 1,2-dichloroethane displayed a linear isotherm. The importance of polar interactions for ametryn sorption was evaluated by normalizing sorption to an "inert" solvent, n-hexane. n-Hexane-normalized sorption of ametryn was much greater than that of phenanthrene, presumably due to ametryn participation in hydrogen bonding interactions. In sharp contrast to sorption to gray chalk, sorption to white (oxidized) chalk is 100- to 1000-fold lower at any given solution concentration. The much greater sorption on gray chalk cannot be explained by specific surface area, clay content, or organic matter content; thus, the nature of the organic matter is considered to control sorption in the chalk samples. Gray chalk sorption capacity estimates for ametryn and 2,4,6-tribromophenol are similar, which, together with evidence of competition for sorption sites, suggests that the limited capacity sorption domain for both compounds is similar.

Adsorption↗

Thromboangiitis obliterans: an old disease in need of a new look.

Almost a century after Buerger's original description of thromboangiitis obliterans, there is still no consensus about diagnostic criteria. The lack of a universally accepted method of diagnosis causes confusion, and mars research efforts. Some authors quote 'hematological disease' as one of the exclusion criteria. But in most recent reports, suspected Buerger patients did not undergo hematological tests to diagnose or rule out any primary or secondary hypercoagulable states. However, immunogenetic studies of Buerger's disease have led to a revived interest in the role of blood coagulation in the pathogenesis of thromboangiitis obliterans. Some association has been suggested between Buerger's disease and the antiphospholipid syndrome, as well as hyperhomocysteinemia. Other thrombophilic conditions have been described anecdotally in patients with Buerger's disease. In view of this developing line of investigation, there is a clear need to redefine the diagnostic algorithm and the criteria for diagnosing Buerger's disease.

Antiphospholipid Syndrome↗