Faculty Bibliography

Agents claimed to be neuroprotective in animal stroke models have all failed in human trials. Thrombolysis has been reported as beneficial in animal and human stroke. We explore the reasons for this disparity, using a review of published results of agents tested both in animal stroke models and in human stroke trials. In animals the effect of neuroprotective agents and of thrombolytic agents on infarct size is time-dependent: early initiation of treatment works best; and benefit is progressively--and eventually totally--lost with increasing delay of time of first treatment. The animal data also show that, overall, the beneficial effects of the neuroprotective agents are weaker, and are totally lost sooner, than those of thrombolytics. The human data show that the failed trials of the neuroprotective agents had entry windows that went far beyond the windows of (any) success seen in tests of these agents in animals. By contrast, human thrombolysis trials uniformly restricted time of entry to windows in which these agents have shown beneficial effect in animals. In clinical stroke trials, neuroprotective agents failed to produce benefit because their effects at best are too weak, and they were used at times predictable from the animal models as too late. Thrombolytic therapy, which has a stronger effect than neuroprotective agents in animal models, was used clinically during the early window of optimal effectiveness, and produced beneficial results. 'Too little/too late' is the recipe for failure in the treatment of ischemic stroke

Comments on the article by E. A. Collacott et al (see record 2000-15087-004) concerning electromagnetic fields efficacy in treating low back pain. The author addresses the comment in Collacott et al's article stating that the depth of the 'source of the pain in our participants . . .may explain the lack of beneficial effect from the magnets used.'

Possible neuroprotective effects of the low molecular weight heparin (LMWH) enoxaparin sodium (Lovenox) were evaluated in a rat model of focal ischemia. Male Sprague-Dawley rats were subjected to 90 min of occlusion of the right middle cerebral artery using the intraluminal suture method. Enoxaparin at doses of 0, 10 or 15 mg/kg was administered to groups of rats 1, 8, 24 and 32 h after artery occlusion. Motor impairment was evaluated by performance on the traverse beam and accelerating rotarod tests. Animals were sacrificed 48 h after occlusion and brain sections were stained with 2% 2,3,5-triphenyltetrazolium chloride for determination of infarct volume. Forty percent of the rats receiving 15 mg/kg enoxaparin died as a result of intracranial hemorrhage. Untreated rats exhibited large lesions involving the caudate putamen and much of the cortex. In enoxaparin - treated rats the damage was mainly confined to the caudate putamen. The sensorimotor behavior of the 10 mg/kg enoxaparin group was significantly better than that of untreated animals. Motor performance of the survivors in the 15 mg/kg group was poor due to hypoactivity and weakness resulting from excessive bleeding. These results suggest that LMWH may have a neuroprotective function

Purpose: The safety and effects on hematocrit of recombinant human erythropoietin (epoetin alfa) were evaluated in men undergoing radical retropubic prostatectomy. Materials and Methods: Between February 1, 1997 and November 2, 1998, 305 men with clinically localized adenocarcinoma of the prostate underwent radical retropubic prostatectomy performed by a single surgeon (H. L.). Of these men 283 with a baseline hematocrit of less than 48% received 600 IU/kg. epoetin alfa 14 days (-14) and 7 days (-7) before radical retropubic prostatectomy. Hematocrit was measured at baseline on day -14, on day -7, just before anesthesia induction on day 0, immediately postoperatively and on the day of discharge home. The number of allogeneic units transfused, and all intraoperative and postoperative complications were recorded, Results: Mean hematocrit at baseline on day -14 and at induction on day 0 was 42<9% and 45<8%, respectively (p = 0<0001). The frequency of hematocrit decreasing, showing no change or increasing 0<1 to 1<9, 2<0 to 3<9 or greater than 4<0 hematocrit points was 16<5%, 0<5%, 23%, 22% and 38%, respectively. Of the men 17% had no increase in hematocrit, A weak correlation existed between baseline hematocrit and the erythropoietic response to epoetin alfa (r(2) = 0<06). Mean change in hematocrit after treatment with epoetin alfa in the quartile baseline hematocrit groups 34<2 to 41<4, 41<5 to 43<2, 43<3 to 44<9 and 45<0 to 48<0 hematocrit points was 3<71, 2<45, 3<86 and 1<02 hematocrit points, respectively. Of the surgical candidates 22 (9<1%) achieved an induction hematocrit of greater than 51%. Of the 283 men receiving epoetin alfa 21 (7<4%) also received an allogeneic transfusion. The transfusion rate did not correlate with induction hematocrit. The only adverse cardiovascular event was an uncomplicated postoperative pulmonary embolus. Conclusions: Our prospective study demonstrates that epoetin alfa given preoperatively in 2 doses of 600 IU/kg. is safe for significantly increasing hematocrit in men before radical retropubic prostatectomy. It is intuitive that the significant increase in hematocrit decreases the requirement for allogeneic blood transfusion

This communication reports the results of investigations on the effect of low molecular weight heparin (LMWH) on intraneuronal calcium release, and considers its possible relevance to the treatment of ischemic stroke. It previously was shown that intraneuronal injection of conventional heparin (MW 12,000) in vitro prevents glutamate-induced calcium release from intracellular stores through its blocking action on IP3 (inositol-1,4,5-triphosphate) receptors, and thus interferes with events occurring in the ischemic cascade. In the experiments reported herein, a LMWH of MW 4500 was shown to have these same effects when injected into a Purkinje cell in an in vitro cerebellar slice preparation, and also when administered externally (bath application). By contrast, conventional heparin works only when injected into the cell; bath application has no effect. The results are interpreted to mean that the larger conventional heparin molecule cannot pass through the cell membrane, while the smaller LMWH molecule does indeed enter the cell. In a clinical trial, LMWH begun within 48 hours of ischemic stroke onset in humans improved outcome at 6 months; conventional heparin given in a similar trial was without benefit. That one anticoagulant was beneficial while another failed suggests the possibility that the difference was independent of effect on the clotting system. The experimental data herein reported support the view that LMWH may benefit stroke victims by an action directly cytoprotective against the consequences of neuronal ischemia

BACKGROUND AND PURPOSE: Many neuroprotective agents (NPAs) are effective in acute experimental cerebral ischemia in animals. None have proven effective in human stroke trials. Even short treatment delays cause substantial efficacy loss. Cardiac surgery under cardiopulmonary bypass (CS-CPB) causes cerebral ischemia with cognitive impairment at a predeterminable time point and should permit efficient screening of NPAs for stroke benefit. We sought to develop sensitive methods to assess dysfunction from CS-CPB in a double-blind trial of the NPA GM1 ganglioside. METHODS: Eighteen GM1 and 11 Control patients received GM1 300 mg or placebo, two doses intravenously, before nonemergency CS-CPB. Independent examiners administered structured neurological examinations and neuropsychological test batteries at Baseline and 1 day (Acute Postop; neurological only), 1 week (Early F/U), and > or = 6 months (Long-term F/U) postoperatively; using defined procedures they employed ordinal Clinical Change Scores (CCSs) to quantify neurological cerebral, neurological noncerebral, and neuropsychological performance changes. Several methods to analyze CCSs and neuropsychological test score changes were evaluated. RESULTS: The most sensitive indicators were the mean Acute Postop Neurologist's CCS-Cerebral (P < 10(-5)) and the mean Early F/U Neuropsychologist's CCS (P < .01), with statistically nonsignificant differences favoring GM1. No significant mean changes in Neurologist's CCS-Noncerebral or any Long-term F/U CCSs occurred. CCS distributions and neuropsychological test score mean changes showed similar temporal patterns, with less sensitivity to change. When, as usual in prior CS-CPB studies, impairment was defined by neuropsychological test score declines (increases ignored), results were spurious. CONCLUSIONS: The strokelike cerebral dysfunction (maximal acutely, with eventual recovery) that occurs after CS-CPB is useful to screen NPAs for clinical efficacy. CCSs based on detailed neurological examination and neuropsychological testing are sensitive measures; refinement of this approach should enhance the efficiency of the CS-CPB model. Further testing of GM1 is warranted