Experimental vascular iujuries induced by activation of platelets were observed under electron microscopy. Twenty eight rabbits were divided into two groups. In the first group, 0.7mg/kg of sodium arachidonate (AA) or 20-40mg/kg of ADP was injected into right carotid artery. AA was injected for 5 seconds and ADP was injected for one minute. In the second group, blood in the carotid arteries was washed out with saline throughout from 10 seconds before to one minute after the injection of AA or ADP. Immediately after, and 5 and 60 minutes after the injection, middle cerebral arteries in the subarachnoid space were isolated and observed under electron microscopy.Immediately after the AA injection, deendothelialization, edematous changes in subendothelial layer and convolution of internal elastic lamina were seen in both groups. Adhesion of platelets on the deendothelialized inner surface was observed frequently. Sixty minutes after, abundant platelet thrombi with fibrin formation were seen. The results suggest the direct effect of AA, as a detergent agent, caused vascular injuries. Immediately after the ADP injection, small aggregates of platelets were seen in the vascular lumen in the first group, whlie the vascular wall showed completely normal finding in the second group. After 5 minutes, remarkable intracytoplasmic vesicular formation in endothelial cells was observed. Edematous changes in subendothelium and even in smooth muscle cells and sporadic deendothelialization were also seen. Adhesion of platelets on the deendothelialized site was seen. After 60 minutes, platelet thrombi with fibrin formation were observed. On the other hand, such injuries were not seen in any of the second group after the ADP injection. The results suggest that the presence of blood, especially aggregation of platelets, must be necessary to produce these vascular injuries.
Prophylactic administration of antibiotics is prevalent for traumatic patients including head injury, when the patients have contaminated wounds, CSF leakage, and multiple injuries. In cases with prolonged fever and inflammatory signs, other antibiotics must be selected without confirming the infections by cultures. Usually, 1st or 2nd generation cefalosporins are selected as empiric therapy for traumatic patients, but, successive antibiotics are usually selected according to the situation. In this study, we analyzed 60 cases of head injured patients with Glasgow Coma Scale under 12, in terms of the selection of antibiotics and the reasons for the antibiotic selections. CEZ > PIPC > FMOX were used for initial treatment without any culture results. The second selection was made without any positive culture results in 85.7%, and tertiary selection without culture results in 50% of the patients. CPR > CFSL > FMOX > PAPM/BP were mainly used as second selection, and IPM/CS > CPR = PIPC were mainly used as tertiary selection. In cases with traumatic brain injuries, it is important to prevent antibiotic resistances. 1) by selecting appropriate antibiotics, 2) by using antibiotics after excluding catheter related infections, 3) by not using antibiotics and performing frequent cultures when no apparent infection focuses are detected.
Thallium (Tl)-201 single-photon emission computed tomography (SPECT) is a useful tool for detecting brain tumors. In this study, we evaluated the utility of Tl-201 SPECT for determining the effect of maintenance chemotherapy with ACNU (nimustine hydrochloride)/VCR (vincristine sulfate) against malignant gliomas. The cases were comprised of 16 glioma cases; 6 astrocytomas, 2 anaplastic astrocytomas, and 8 glioblastomas. We first analyzed the correlation between Tl-201 uptake ratio and proliferative activity of the tumor, using Ki-67 immunohistochemistry in 13 cases of glioma. The uptake ratio of Tl-201 correlated with the Ki-67 staining indices (SI), and a closer correlation was obtained using Tl-201 delayed images than with the early images. We also analyzed the chronological changes of Tl-201 uptake ratio and volume of abnormal area evaluated by MRI T2-weighted imaging (MRI T2WI), in 10 cases of malignant glioma during maintenance chemotherapy. The Tl-201 uptake ratio gradually decreased with the effect of maintenance chemotherapy, and the sensitivity was superior to MRI findings. Together with MRI, Tl-201 SPECT is considered to be a useful indicator for evaluating the effect of maintenance chemotherapy against malignant gliomas.
A thirty-year-old male was transferred to our emergency department after being injured in an automobile accident. He was conscious at the time of admission. Chest X-ray revealed fracture of the left first rib and a gradually increasing mediastinal shadow, which suggested injury to the subclavian artery. On the day of injury, the patient exhibited right hemiparesis, without any abnormality on head CT scan. There was no laterality or blood flow reduction on SPECT, and no major vessel occlusions were detected with using TCD. Thoracic CT scan revealed fractures of the 4th and 5th thoracic vertebrae, but no spinal cord injuries were found using MRI. Angiography revealed complete occlusion of the left common carotid artery and collateral circulation. His right hemiparesis gradually improved, and MRI revealed no infarcted lesion in the brain. In this case, blunt thoraco-cervical trauma caused fracture of the first rib, which has lead to injury of the carotid artery and jugular vein. These major vessel injuries led to transient hemiparesis and increasing mediastinal bleeding. Carotid artery injury is a rare complication of traumatic head and neck injury, and common carotid injury caused by thoraco-cervical trauma is extremely rare. Angiography is the gold standard for diagnosis of such vessel injuries, and aggressive examination is recommended for such complicated injuries.
We have found that vascular injuries are induced by intravascular aggregation of platelets activated by arachidonic acid (AA) or ADP. The characteristic findings are the appearance of vacuoles in endothelial cells and eventual deendothelialization. In deendothelialized regions, formation of platelet thrombi was observed. The platelets in the thrombi were stained with 2T60, a monoclonal antibody that recognizes activated platelets. The change was more remarkable in the AA-injected animals because AA has a stronger platelet activating effect and a detergent effect on the endothelium. The ADP-injection experiments clarified the role of platelets in vascular injury. These findings suggest that activated platelets play a role in the genesis of vascular injuries, and that their role is related to thrombus formation.
