Percutaneous radiofrequency rhizotomy of lumbar spinal facets: The results of 46 cases

The results of percutaneous radiofrequency rhizotomy of lumbar spinal facets in 46 patients followed at least three months (mean 15 months) are reported and compared with those reported previously. Satisfactory pain relief three months after the procedure was achieved in 36.4 percent of patients without operations and in 41.7 percent of patients with operations other than fusion.No patient had previously undergone fusion.Treatment of low-back pain by using radio-frequency thermocoagulation of spinal facets is a simple, safe, and well-tolerated procedure. It can be used to relief of pain in spite of decreasing rates of success within the follow-up period.     

The effects of verapamil on left ventricular function in the presence of beta-adrenergic blockade

Supraventricular tachyarrhythmias frequently complicate myocardial revascularization. Intravenous administration of verapamil has been effective in terminating these arrhythmias. To determine the effects of verapamil on left ventricular systolic function, we implanted ultrasonic dimension transducers in dogs and, after they had recovered from the operation, studied them while they were awake and unsedated. Intravenous administration of verapamil (0.2 mg/kg) resulted in an elevation of cardiac output above baseline because of reflex-induced tachycardia. Contractility, as measured by the load-independent end-systolic pressure-volume relationship, remained unchanged. When the animals were pretreated with atropine and propranolol, verapamil resulted in a fall in cardiac output and contractility. The intact animal responded to the vasodilatory effect of verapamil by releasing catecholamines to maintain cardiac output and hemodynamic stability. Only when this compensatory mechanism was blocked by a beta-adrenergic blocker do the inherently negative inotropic and chronotropic effects of verapamil become apparent. The clinical ramifications of this finding are of greater importance to the surgeon as more patients receive beta-adrenergic blocking agents up to the time of the immediate preoperative period. We conclude that verapamil should be administered with caution to patients with supraventricular tachyarrhythmias who have been receiving beta-adrenergic blocking agents.     

Perceptions of first and third year medical students on self-study and reporting processes of problem-based learning

Background  

The objective of this study is to investigate the perceptions of first and third year medical students on self-study and reporting processes of Problem-based Learning (PBL) sessions and their usage of learning resources.     

PS2 and HSP70 expression in rectal adenocarcinomas: an immunohistochemical investigation of 45 cases.

OBJECTIVE: To evaluate the expression of HSP70 and pS2 and to determine whether it may be an additional prognostic variable in the prediction of recurrence and survival in rectal adenocarcinomas. METHODS: The paraffin sections of 45 patients with rectal carcinoma who were treated with surgical resection were stained with HSP70 and pS2 antibodies by using the standard biotin immunoperoxidase method. Cytoplasmic staining for both antibodies was scored semiquantitatively. RESULTS: Only 16 (35.6%) tumors showed a positive cytoplasmic reaction with HSP70 antibody, while pS2 expression was observed in 26 (57.8%) tumors. There was an association between HSP70 and pS2 expression (P=0.002). No correlations were found between HSP70 and pS2 expression and tumor recurrence or overall survival and other prognostic factors. However, the type of surgical resection was significantly associated with pS2 expression status (P=0.013). Significant correlations were detected between tumor recurrence and other clinicopathologic parameters, such as clinical stage, lymph node involvement, and resection type (P=0.015, P=0.015, and P=0.03, respectively). Resection type was significantly associated with clinical outcome, recurrence, and metastasis (P=0.009, P=0.03, P<0.01, respectively). In addition, there was a statistically significant relationship between clinical stage and final outcome (P=0.005). CONCLUSIONS: The strong correlation between pS2 expression and incomplete surgical resection suggests that pS2 may be related to invasive tumor behavior and may also play a role in tumor recurrence, although this latter association did not reach statistical significance in this study. HSP70 expression does not appear to be related to tumor invasiveness or tumor recurrence.     

Competition-based cellular peptide binding assays for 13 prevalent HLA class I alleles using fluorescein-labeled synthetic peptides

We report the development, validation, and application of competition-based peptide binding assays for 13 prevalent human leukocyte antigen (HLA) class I alleles. The assays are based on peptide binding to HLA molecules on living cells carrying the particular allele. Competition for binding between the test peptide of interest and a fluorescein-labeled HLA class I binding peptide is used as read out. The use of cell membrane-bound HLA class I molecules circumvents the need for laborious biochemical purification of these molecules in soluble form. Previously, we have applied this principle for HLA-A2 and HLA-A3. We now describe the assays for HLA-A1, HLA-A11, HLA-A24, HLA-A68, HLA-B7, HLA-B8, HLA-B14, HLA-B35, HLA-B60, HLA-B61, and HLA-B62. Together with HLA-A2 and HLA-A3, these alleles cover more than 95% of the Caucasian population. Several allele-specific parameters were determined for each assay. Using these assays, we identified novel HLA class I high-affinity binding peptides from HIVpol, p53, PRAME, and minor histocompatibility antigen HA-1. Thus these convenient and accurate peptide-binding assays will be useful for the identification of putative cytotoxic T lymphocyte epitopes presented on a diverse array of HLA class I molecules.     

Early Protective Effects of Iloprost after Experimental Spinal Cord Ischemia in Rabbits

The potential role of Iloprost, a stable analogue of prostocyclin, in treating spinal cord ischemia was investigated in rabbits subjected to aortic occlusion for 15 minutes. Ten adult rabbits weighing 2-2.5 kg received an intravenous infusion of saline (SF) as a control group and 14 rabbits received an intravenous infusion of Iloprost, 25 microg/kg/h. Iloprost infusion was started immediately after clamping of the aorta and continued 60 minutes thereafter. Cortical somatosensorial evoked potentials (CSEP) were recorded during the pre-ischemic period as a baseline and post-ischemic readings were taken at 15, 30 and 60 minutes. There was no statistically significant difference between CSEP of the saline and Iloprost treated groups (p < 0.05). All animals were examined neurologically by using a modification of Tarlov scale and all subjects were then deeply anesthetized and their spinal cords were removed for light and electron microscopic examinations at 24 h after spinal cord ischemia. In order to obtain an accurate comparison of ultrastructural changes between saline treated and Iloprost treated groups, a grading scale was performed. The light microscopic and ultrastructural analysis of the Iloprost treated group revealed that there was moderate protection of the myelin and axons and edema was attenuated. Findings of this study suggest that Iloprost exerts a protective effect on spinal cord ischemia. However, further studies are needed to reveal possible mechanisms of protection provided by Iloprost.     

Effects of Different Doses of Epidural Midazolam on Spinal Somatosensory Evoked Potentials

Summary  The aim of this study is to find out the effects of different doses of midazolam, when used epidurally, on somatosensory evoked potentials (SEP) by delaying neuronal conduction. Thirty two New Zeland albino male rabbits were divided into four groups. All rabbits were anesthetised with ketamine and xylasine combination and atracurium was used as muscle relaxant. 10 mg/kg/hr ketamine infusion was used for maintenance of anesthesia. After insertion of the epidural catheter surgically; Group 1 received 1.5 ml isotonic saline (Control), Group 2 received 150 μg/kg, Group 3 received 250 μg/kg, and Group 4 received 500 μg/kg midazolam epidurally. With the stimulation of sciatic nerve, SEP records were recorded from the epidural space. Records were received before the injection of the drug, and 20, 40, 60 minutes after injection of the drug.  “Latancy” results were increased according to control in all groups (including isotonic saline-control-group). Increase in latancy in the control group was interpreted as due to the effect of temperature mismatch of the saline and the rabbits. While in the first and second group amplitudes showed no differences, group 3 and 4 showed decreases of up to 50%. Epidurally administered midazolam up to 150 μg/kg caused no change in SEP records, but 250 and 500 μg/kg doses caused decreases in SEP records which can lead to misinterpretation as neurological damage.