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Biomedical subjects

A Wakai

Publications and source records attributed to A Wakai.

27 records · Page 2Linked to original sources
PubMed2001

Tourniquet-induced systemic inflammatory response in extremity surgery.

BACKGROUND: Tourniquet-induced reperfusion injury in animals produces significant systemic inflammatory effects. This study investigated whether a biologic response occurs in a clinically relevant model of tourniquet-induced reperfusion injury. METHODS: Patients undergoing elective knee arthroscopy were prospectively randomized into controls (no tourniquet) and subjects (tourniquet-controlled). The effects of tourniquet-induced reperfusion on monocyte activation state, neutrophil activation state, and transendothelial migration (TEM) were studied. Changes in the cytokines implicated in reperfusion injury, tumor necrosis factor-alpha, interleukin (IL)-1beta, and IL-10 were also determined. RESULTS: After 15 minutes of reperfusion, neutrophil and monocyte activation were significantly increased. Pretreatment of neutrophils with pooled subject (ischemia-primed) plasma significantly increased TEM. In contrast, TEM was not significantly altered by ischemia-primed plasma pretreatment of the endothelial monolayer. Significant elevation of tumor necrosis factor-alpha and IL-1beta were observed in subjects compared with controls after 15 minutes of reperfusion. There was no significant difference in serum IL-10 levels between the groups at all the time points studied. CONCLUSION: These results indicate a transient neutrophil and monocyte activation after tourniquet-ischemia that translates into enhanced neutrophil transendothelial migration with potential for tissue injury.

Adult↗
PubMed2001

Adenosine inhibits neutrophil vascular endothelial growth factor release and transendothelial migration via A2B receptor activation.

The effects of adenosine on neutrophil (polymorphonuclear neutrophils; PMN)-directed changes in vascular permeability are poorly characterized. This study investigated whether adenosine modulates activated PMN vascular endothelial growth factor (vascular permeability factor; VEGF) release and transendothelial migration. PMN activated with tumour necrosis factor-alpha (TNF-alpha, 10 ng/mL) were incubated with adenosine and its receptor-specific analogues. Culture supernatants were assayed for VEGF. PMN transendothelial migration across human umbilical vein endothelial cell (HUVEC) monolayers was assessed in vitro. Adhesion molecule receptor expression was assessed flow cytometrically. Adenosine and some of its receptor-specific analogues dose-dependently inhibited activated PMN VEGF release. The rank order of potency was consistent with the affinity profile of human A2B receptors. The inhibitory effect of adenosine was reversed by 3,7-dimethyl-1-propargylxanthine, an A2 receptor antagonist. Adenosine (100 microM) or the A2B receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA, 100 microM) significantly reduced PMN transendothelial migration. However, expression of activated PMN beta2 integrins and HUVEC ICAM-1 were not significantly altered by adenosine or NECA. Adenosine attenuates human PMN VEGF release and transendothelial migration via the A2B receptor. This provides a novel target for the modulation of PMN-directed vascular hyperpermeability in conditions such as the capillary leak syndrome.

Adenosine↗
PubMed2000

Mannitol for acute traumatic brain injury.

BACKGROUND: Mannitol is sometimes dramatically effective in reversing acute brain swelling, but its effectiveness in the on-going management of severe head injury remains open to question. There is evidence that in prolonged dosage mannitol may pass from the blood into the brain, where it might cause reverse osmotic shifts that increase intracranial pressure. OBJECTIVES: To assess the effects of different mannitol therapy regimens, of mannitol compared to other intracranial pressure (ICP) lowering agents, and to quantify the effectiveness of mannitol administration given at other stages following acute traumatic brain injury. SEARCH STRATEGY: The review drew on the search strategy for the Injuries Group as a whole. We checked reference lists of trials and review articles, and contacted authors of trials. SELECTION CRITERIA: Randomised trials of mannitol, in patients with acute traumatic brain injury of any severity. The comparison group could be placebo-controlled, no drug, different dose, or different drug. Trials where the intervention was started more than eight weeks after injury, and cross-over trials were excluded. DATA COLLECTION AND ANALYSIS: The reviewers independently rated quality of allocation concealment and extracted the data. Relative risks (RR) and 95% confidence intervals (CI) were calculated for each trial on an intention to treat basis. MAIN RESULTS: Overall there were few eligible trials. There were no trials comparing different doses, or type of administration. One trial compared ICP-directed therapy to 'standard care' (RR for death= 0.83; 95% CI 0.47;1.46). One trial compared mannitol to pentobarbital (RR for death = 0.85; 95% CI 0. 52;1.38). No trials compared mannitol to other ICP lowering agents. One trial tested the effectiveness of pre-hospital administration of mannitol against placebo (RR for death=1.59; 95% CI 0.44;5.79). REVIEWER'S CONCLUSIONS: There are insufficient data to recommend one form of mannitol infusion over another. Mannitol therapy for raised ICP may have a beneficial effect on mortality when compared to pentobarbital treatment. ICP-directed treatment shows a small beneficial effect compared to treatment directed by neurological signs and physiological indicators. There are insufficient data on the effectiveness of pre-hospital administration of mannitol to preclude either a harmful or a beneficial effect on mortality.

Brain Injuries↗
PubMed2000

Is human fracture hematoma inherently angiogenic?

This study attempts to explain the cellular events characterizing the changes seen in the medullary callus adjacent to the interfragmentary hematoma during the early stages of fracture healing. It also shows that human fracture hematoma contains the angiogenic cytokine vascular endothelial growth factor and has the inherent capability to induce angiogenesis and thus promote revascularization during bone repair. Patients undergoing emergency surgery for isolated bony injury were studied. Raised circulating levels of vascular endothelial growth factor were seen in all injured patients, whereas the fracture hematoma contained significantly higher levels of vascular endothelial growth factor than did plasma from these injured patients. However, incubation of endothelial cells in fracture hematoma supernatant significantly inhibited the in vitro angiogenic parameters of endothelial cell proliferation and microtubule formation. These phenomena are dependent on a local biochemical milieu that does not support cytokinesis. The hematoma potassium concentration is cytotoxic to endothelial cells and osteoblasts. Subcutaneous transplantation of the fracture hematoma into a murine wound model resulted in new blood vessel formation after hematoma resorption. This angiogenic effect is mediated by the significant concentrations of vascular endothelial growth factor found in the hematoma. This study identifies an angiogenic cytokine involved in human fracture healing and shows that fracture hematoma is inherently angiogenic. The differences between the in vitro and in vivo findings may explain the phenomenon of interfragmentary hematoma organization and resorption that precedes fracture revascularization.

Adult↗
PubMed2000

Thromboprophylaxis using a low molecular weight heparin delays fracture repair.

Low molecular weight heparins are significantly superior to unfractionated heparin or warfarin in the prevention of thromboembolic episodes associated with orthopaedic surgery. Therapeutic doses of heparin and warfarin have been shown to delay bone repair in a rabbit model. The current study investigated the effect of prophylactic administration of a low molecular weight heparin, enoxaparin, on the healing of a closed rabbit rib fracture. Fracture healing was assessed using histomorphometric, histologic, and immunohistochemical methods at 3, 7, and 14 days, and biomechanical testing with torsional loading was assessed after 21 days. Bone repair was significantly attenuated at all times in animals receiving subcutaneous enoxaparin compared with that of the control animals. Numerous putative mechanisms for this phenomenon are discussed, and additional studies are proposed to elucidate the effects of this pharmacologically diverse group of compounds on all aspects of bone physiology and repair.

Animals↗
PubMedDate not supplied

Pneumatic tourniquets in extremity surgery.

Pneumatic tourniquets maintain a relatively bloodless field during extremity surgery, minimize blood loss, aid identification of vital structures, and expedite the procedure. However, they may induce an ischemia-reperfusion injury with potentially harmful local and systemic consequences. Modern pneumatic tourniquets are designed with mechanisms to regulate and maintain pressure. Routine maintenance helps ensure that these systems are working properly. The complications of tourniquet use include postoperative swelling, delay of recovery of muscle power, compression neurapraxia, wound hematoma with the potential for infection, vascular injury, tissue necrosis, and compartment syndrome. Systemic complications can also occur. The incidence of complications can be minimized by use of wider tourniquets, careful preoperative patient evaluation, and adherence to accepted principles of tourniquet use.

Emergencies↗
PubMedDate not supplied

Unilateral diaphragmatic agenesis precluding laparoscopic cholecystectomy.

BACKGROUND: Complete absence of a hemidiaphragm or diaphragmatic agenesis in adulthood is rare with only one previous report in the literature. Its significance in relation to performing laparoscopic procedures has not been documented previously. METHODS: We report a case of previously undiagnosed diaphragmatic agenesis in adulthood precluding laparoscopic cholecystectomy and comprehensively review the literature for papers relevant to diaphragmatic agenesis in adulthood. RESULTS: Diaphragmatic agenesis in adulthood may complicate and preclude laparoscopic cholecystectomy. The principles of investigation and management of diaphragmatic agenesis complicating laparoscopic surgery are discussed. CONCLUSIONS: In adults with diaphragmatic agenesis and intrathoracic abdominal viscera precluding laparoscopic cholecystectomy, conservative management is recommended.

Adult↗