Increased levels of basic fibroblast growth factor (bFGF) following focal brain injury

Focal injury to the mammalian central nervous system (CNS) results in a cascade of cellular responses - including glial and capillary proliferation and neural sprouting - that contribute to the repair of neural tissue and to the recovery of neurological function. Fibroblast growth factors (FGFs) are heparin-binding polypeptides with potent trophic effects on CNS glia, endothelia, and neurons; both acidic and basic forms are found in the mammalian CNS. We used heparin-affinity chromatography coupled to Balb/c 3T3 mitogenic assay to show a marked increase in levels of bioactive FGFs in tissue surrounding focal cortical lesions of the mature rat brain at one week after injury. Heparin-affinity HPLC showed that this increase was due to a large increase in levels of basic FGF (bFGF), and a much smaller increase in levels of acidic FGF (aFGF) after injury. Increased bFGF bioactivity was paralleled by increased levels of immunoreactive bFGF, as assessed by Western blotting techniques. Increased bFGF levels may play an important role in the cascade of cellular reactions occurring after focal brain injury.

A functional MRI study of three motor tasks in the evaluation of stroke recovery

Functional brain imaging studies have provided insights into the processes related to motor recovery after stroke. The comparative value of different motor activation tasks for probing these processes has received limited study. We hypothesized that different hand motor tasks would activate the brain differently in controls, and that this would affect control-patient comparisons. Functional magnetic resonance imaging (MRI) was used to evaluate nine control subjects and seven patients with good recovery after a left hemisphere hemiparetic stroke. The volume of activated brain in bilateral sensorimotor cortex and four other motor regions was compared during each of three tasks performed by the right hand: index-finger tapping, four-finger tapping, and squeezing. In control subjects, activation in left sensorimotor cortex was found to be significantly larger during squeezing as compared with index-finger tapping. When comparing control subjects with stroke patients, patients showed a larger volume of activation in right sensorimotor cortex during index-finger tapping but not with four-finger tapping or squeezing. In addition, patients also showed a trend toward larger activation volume than controls within left supplementary motor area during index-finger tapping but not during the other tasks. Motion artifact was more common with squeezing than with the tapping tasks. The choice of hand motor tasks used during brain mapping can influence findings in control subjects as well as the differences identified between controls and stroke patients. The results may be useful for future studies of motor recovery after stroke.

Functional magnetic resonance imaging of reorganization in rat brain after stroke

Functional recovery after stroke has been associated with brain plasticity; however, the exact relationship is unknown. We performed behavioral tests, functional MRI, and histology in a rat stroke model to assess the correlation between temporal changes in sensorimotor function, brain activation patterns, cerebral ischemic damage, and cerebrovascular reactivity. Unilateral stroke induced a large ipsilateral infarct and acute dysfunction of the contralateral forelimb, which significantly recovered at later stages. Forelimb impairment was accompanied by loss of stimulus-induced activation in the ipsilesional sensorimotor cortex; however, local tissue and perfusion were only moderately affected and cerebrovascular reactivity was preserved in this area. At 3 days after stroke, extensive activation-induced responses were detected in the contralesional hemisphere. After 14 days, we found reduced involvement of the contralesional hemisphere, and significant responses in the infarction periphery. Our data suggest that limb dysfunction is related to loss of brain activation in the ipsilesional sensorimotor cortex and that restoration of function is associated with biphasic recruitment of peri- and contralesional functional fields in the brain.

Intravenous basic fibroblast growth factor produces a persistent reduction in infarct volume following permanent focal ischemia in rats

Basic fibroblast growth factor (bFGF) is a polypeptide with potent survival-promoting and protective effects on brain cells. In previous studies, we showed that intravenous administration of bFGF reduced infarct volume in models of focal cerebral ischemia in rats, mice, and cats. In these previous studies, infarct volume was measured within 1-7days of the onset of ischemia. The current study was undertaken to determine whether the reduction in infarct volume by bFGF was persistent beyond the first week after stroke. Mature male Sprague-Dawley rats received an intravenous infusion of bFGF (50 microg/kg per h) or vehicle during 0.5-3.5h after permanent proximal middle cerebral artery occlusion. We found a 27% reduction in infarct volume in bFGF- compared to vehicle-treated animals at three months after infarction (P<0.05). The data show that intravenous bFGF treatment produces a persistent reduction in infarct volume, at least up to three months following focal stroke.

Intravenous basic fibroblast growth factor (bFGF) decreases DNA fragmentation and prevents downregulation of Bcl-2 expression in the ischemic brain following middle cerebral artery occlusion in rats

In previous studies, we showed that basic fibroblast growth factor (bFGF) reduced infarct volume when infused intravenously in animal models of focal cerebral ischemia. In the current study, we examined the potential mechanism of infarct reduction by bFGF, especially effects on apoptosis within the ischemic brain. We found that bFGF decreased DNA fragmentation in the ischemic hemisphere, as assessed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) histochemical methods combined with morphological criteria. bFGF also prevented reduction of immunoreactivity of the anti-apoptotic protein Bcl-2 in the ischemic hemisphere, but did not alter immunoreactivity of the pro-apoptotic proteins Bax, Caspase-1, or Caspase-3. These changes in TUNEL histochemistry and Bcl-2 immunoreactivity were especially prominent in cortex at the borders ('penumbra') of infarcts, spared by bFGF treatment. We conclude that the infarct-reducing effects of bFGF may be due, in part, to prevention of downregulation of Bcl-2 expression and decreased apoptosis in the ischemic brain.

Time window of intracisternal osteogenic protein-1 in enhancing functional recovery after stroke

Osteogenic protein-1 (OP-1, BMP-7) is a member of the bone morphogenetic protein subfamily of the TGF-ss superfamily that selectively stimulates dendritic neuronal outgrowth. In previous studies, we found that the intracisternal injection of OP-1, starting at one day after stroke, enhanced sensorimotor recovery of the contralateral limbs following unilateral cerebral infarction in rats. In the current study, we further explored the time window during which intracisternal OP-1 enhances sensorimotor recovery, as assessed by limb placing tests. We found that intracisternal OP-1 (10 microg) given 1 and 3 days, or 3 and 5 days, but not 7 and 9 days after stroke, significantly enhanced recovery of forelimb and hindlimb placing. There was no difference in infarct volume between vehicle- and OP-1-treated animals. The mechanism of OP-1 action might be stimulation of new dendritic sprouting in the remaining uninjured brain.

A pilot study of somatotopic mapping after cortical infarct

BACKGROUND AND PURPOSE

Animal studies have described remodeling of sensory and motor representational maps after cortical infarct. These changes may contribute to return of function after stroke.

METHODS

Functional MRI was used to compare sensory and motor maps obtained in 35 normal control subjects with results from 2 patients with good recovery 6 months after a cortical stroke.

RESULTS

During finger tapping in controls, precentral gyrus activation exceeded or matched postcentral gyrus activation in 40 of 42 cases. Patient 1 had a small infarct limited to precentral gyrus. Finger tapping activated only postcentral gyrus, a pattern not seen in any control subject. During tactile stimulation of a finger or hand in controls, postcentral gyrus activation exceeded or matched precentral gyrus activation in 11 of 14 cases. Patient 2 had a small infarct limited to postcentral gyrus and superior parietal lobule. Tactile stimulation of the finger activated only precentral gyrus, a pattern not seen in any control. In both patients, activation during pectoralis contraction was medial to the site activated during finger tapping.

CONCLUSIONS

Results during finger tapping (patient 1) and finger stimulation (patient 2) may reflect amplification of a preserved component of normal sensorimotor function, a shift in the cortical site of finger representation, or both. Cortical map reorganization along the infarct rim may be an important contributor to recovery of motor and sensory function after stroke. Functional MRI is useful for assessing motor and sensory representational maps.

Intracisternal antisense oligonucleotide to growth associated protein-43 blocks the recovery-promoting effects of basic fibroblast growth factor after focal stroke

Focal infarction (stroke) of the lateral cerebral cortex of rats (including the sensorimotor cortex) produces deficits in sensorimotor function of the contralateral limbs that recover partially over time. In previous studies, we found that the intracisternal injection of basic fibroblast growth factor (bFGF), a potent neurotrophic growth factor, starting at 1 day after stroke, significantly enhanced recovery of sensorimotor function of the contralateral forelimb and hindlimb. Moreover, immunoreactivity (IR) for growth-associated protein-43 (GAP-43), a molecular marker of new axonal growth, was increased in the intact contralateral sensorimotor cortex following bFGF treatment. In the current study, we found that the intracisternal administration of antisense, but not missense, oligonucleotide to GAP-43 blocked the recovery-enhancing effects of bFGF and blocked the increase in GAP-43 IR in the contralateral cortex. These results suggest that upregulation of GAP-43 expression and consequent enhanced axonal sprouting in intact uninjured parts of the brain are likely mechanisms for the recovery-promoting effects of bFGF.

Potential usefulness of basic fibroblast growth factor as a treatment for stroke

Within the past few years, a growing body of evidence has accumulated indicating that exogenously administered neurotrophic growth factors may limit the extent of acute ischemic neural injury and enhance functional neurorecovery following stroke. One of the most widely studied growth factor in this regard is basic fibroblast growth factor (bFGF). In preclinical studies, bFGF administered intravenously within hours after the onset of ischemia reduces infarct size, presumably due to direct protection of cells at the borders (penumbra) of cerebral infarction. On the other hand, if bFGF is administered intracisternally starting at one day after ischemia, infarct size is not reduced, but recovery of sensorimotor function of the impaired limbs is increased, presumably due to enhancement of new neuronal sprouting and synapse formation in the intact uninjured brain. Clinical trials of the intravenous administration of bFGF as a cytoprotective agent in acute stroke are in progress. Trials of the delayed administration of bFGF as a recovery-promoting agent in subacute stroke are anticipated.

Basic fibroblast growth factor enhances axonal sprouting after cortical injury in rats

The trophic factors responsible for initiating and guiding the outgrowth of axons have proven to be elusive throughout most of this century. Entorhinal cortex injury, which denervates the hippocampal formation of rats, induces axonal sprouting by several surviving hippocampal afferents and results in a significant elevation of growth factors, one of which is basic fibroblast growth factor (bFGF). The possibility that bFGF may regulate lesion-induced hippocampal sprouting was examined by making i.v. bFGF infusions into rats with unilateral entorhinal lesions. Basic FGF treatment significantly increased sprouting by the cholinergic septodentate pathway. Thus, the increase in bFGF following central nervous system injury may signal its role in the regulation of injury-related axonal remodeling of a cholinergic pathway.

Activation of distinct motor cortex regions during ipsilateral and contralateral finger movements

Previous studies have shown that unilateral finger movements are normally accompanied by a small activation in ipsilateral motor cortex. The magnitude of this activation has been shown to be altered in a number of conditions, particularly in association with stroke recovery. The site of this activation, however, has received limited attention. To address this question, functional magnetic resonance imaging (MRI) was used to study precentral gyrus activation in six control and three stroke patients during right index finger tapping, then during left index finger tapping. In each hemisphere, the most significantly activated site (P < 0.001 required) was identified during ipsilateral and during contralateral finger tapping. In the motor cortex of each hemisphere, the site activated during use of the ipsilateral hand differed from that found during use of the contralateral hand. Among the 11 control hemispheres showing significant activation during both motor tasks, the site for ipsilateral hand representation (relative to contralateral hand site in the same hemisphere) was significantly shifted ventrally in all 11 hemispheres (mean, 11 mm), laterally in 10/11 hemispheres (mean, 12 mm), and anteriorly in 8/11 hemispheres (mean, 10 mm). In 6 of 11 hemispheres, tapping of the contralateral finger simultaneously activated both the ipsilateral and the contralateral finger sites, suggesting bilateral motor control by the ipsilateral finger site. The sites activated during ipsilateral and contralateral hand movement showed similar differences in the unaffected hemisphere of stroke patients. The region of motor cortex activated during ipsilateral hand movements is spatially distinct from that identified during contralateral hand movements.

Estradiol protects against ischemic injury

Clinical studies demonstrate that estrogen replacement therapy in postmenopausal women may enhance cognitive function and reduce neurodegeneration associated with Alzheimer's disease and stroke. This study assesses whether physiologic levels of estradiol prevent brain injury in an in vivo model of permanent focal ischemia. Sprague-Dawley rats were ovariectomized; they then were implanted, immediately or at the onset of ischemia, with capsules that produced physiologically low or physiologically high 17beta-estradiol levels in serum (10 or 60 pg/mL, respectively). One week after ovariectomy, ischemia was induced. Estradiol pretreatment significantly reduced overall infarct volume compared with oil-pretreated controls (mean+/-SD: oil = 241+/-88; low = 139+/-91; high = 132+/-88 mm3); this protective effect was regionally specific to the cortex, since no protection was observed in the striatum. Baseline and ischemic regional CBF did not differ between oil and estradiol pretreated rats, as measured by laser Doppler flowmetry. Acute estradiol treatment did not protect against ischemic injury. Our finding that estradiol pretreatment reduces injury demonstrates that physiologic levels of estradiol can protect against neurodegeneration.

Quantitative assessment of mirror movements after stroke

BACKGROUND AND PURPOSE

Mirror movements (MM) are involuntary synchronous movements of one limb during voluntary unilateral movements of the opposite limb. We measured MM in stroke and control subjects and evaluated whether MM after stroke are related to motor function.

METHODS

Twenty-three patients and 16 control subjects were studied. A computerized dynamometer was used during two squeezing tasks to measure intended movements from the active hand as well as MM from the opposite hand. Motor deficits were measured with the arm motor component of the Fugl-Meyer scale.

RESULTS

During paretic hand squeezing, MM in the unaffected hand were detected in 70% (repetitive squeeze) to 78% (sustained squeeze) of stroke patients. For both tasks, this was significantly (P < 0.05) greater than the incidence of MM in the paretic hand or in either hand of control subjects (17% to 44%), except when compared with the incidence of MM in the dominant hand of control subjects (56%; P = 0.17). The incidence of MM in the paretic hand was not significantly different from that seen in either hand of control subjects. Patients with MM in the unaffected hand had significantly greater motor deficit than patients without MM. Patients with MM in the paretic hand had significantly better motor function than patients without MM.

CONCLUSIONS

Simultaneously recording motor performances of both hands provides precise information to characterize MM. MM in the unaffected hand and in the paretic hand are associated with different degrees of motor deficit after stroke. Evaluation of MM may be useful for studying mechanisms of stroke recovery.

Intracisternal osteogenic protein-1 enhances functional recovery following focal stroke

Osteogenic protein-1 (OP-1, BMP-7) is a member of the transforming growth factor-beta (TGF-beta) superfamily that selectively induces dendritic outgrowth from cultured neurons. We injected human recombinant OP-1 (1 or 10 micrograms) or vehicle into the cisterna magna of mature male Sprague-Dawley rats 1 and 4 days after focal cerebral infarction induced by middle cerebral artery (MCA) occlusion. OP-1 treatment was associated with a marked enhancement of recovery of sensorimotor function of the impaired forelimb and hindlimb (contralateral to infarcts) as assessed by limb placing tests. This effect appeared to be dose dependent. There was no difference in infarct volume between OP-1 and vehicle-treated rats. The mechanisms of enhanced recovery by intracisternal OP-1 may include promotion of dendritic sprouting in the intact uninjured brain.

A functional MRI study of subjects recovered from hemiparetic stroke

BACKGROUND AND PURPOSE

Stroke recovery mechanisms remain incompletely understood, particularly for subjects with cortical stroke, in whom limited data are available. We used functional magnetic resonance imaging to compare brain activations in normal controls and subjects who recovered from hemiparetic stroke.

METHODS

Functional magnetic resonance imaging was performed in ten stroke subjects with good recovery, five with deep, and five with cortical infarcts. Brain activation was achieved by index finger-tapping. Statistical parametric activation maps were obtained using a t test and a threshold of P < .001. In five bilateral motor regions, the volume of activated brain for each stroke subject was compared with the distribution of activation volumes among nine controls.

RESULTS

Control subjects activated several motor regions. During recovered hand finger-tapping, stroke subjects activated the same regions as controls, often in a larger brain volume. In the unaffected hemisphere, sensorimotor cortex activation was increased in six of nine stroke subjects compared with controls. Cerebellar hemisphere contralateral and premotor cortex ipsilateral to this region, as well as supplementary motor areas, also had increased activation. In the stroke hemisphere, activation exceeding controls was uncommon, except that three of five cortical strokes showed peri-infarct activation foci. During unaffected hand finger-tapping, increased activation by stroke subjects compared with controls was uncommon; however, decreased activation was seen in unaffected sensorimotor cortex, suggesting that this region's responsiveness increased to the ipsilateral hand and decreased to contralateral hand movements. Use of a different threshold for defining activation (P < .01) did not change the overall findings (kappa = .75).

CONCLUSIONS

Recovered finger-tapping by stroke subjects activated the same motor regions as controls but to a larger extent, particularly in the unaffected hemisphere. Increased reliance on these motor areas may represent an important component of motor recovery. Functional magnetic resonance imaging studies of subjects who recovered from stroke provide evidence for several processes that may be related to restoration of neurologic function.

Computerized measurement of motor performance after stroke

BACKGROUND AND PURPOSE

Stroke scales usually convert motor status to a score along an ordinal scale and do not provide a permanent recording of motor performance. Computerized methods sensitive to small changes in neurological status may be of value for studying and measuring stroke recovery.

METHODS

We developed a computerized dynamometer and tested 23 stroke subjects and 12 elderly control subjects on three motor tasks: sustained squeezing, repetitive squeezing, and index finger tapping. For each subject, scores on the Fugl-Meyer and National Institutes of Health stroke scales were also obtained.

RESULTS

Sustained squeezing by the paretic hand of stroke subjects was weaker (9.2 kg) than the unaffected hand (20.2 kg; P < .0005), as well as control dominant (23.1 kg; P < .0005) and nondominant (19.9 kg; P < .005) hands. Paretic index finger tapping was slower (2.5 Hz) than the unaffected hand (4.2 Hz; P < .01), as well as control dominant (4.7 Hz; P < .0005) and nondominant (4.9 Hz; P < .0005) hands. Many features of dynamometer data correlated significantly with stroke subjects' Fugl-Meyer scores, including sustained squeeze maximum force (rho = .91) and integral of force over 5 seconds (rho = .91); repetitive squeeze mean force (rho = .92) and mean frequency (rho = .73); and index finger tap mean frequency (rho = .83). Correlation of these motor parameters with National Institutes of Health stroke scale score was weaker in all cases, a consequence of the scoring of nonmotor deficits on this scale. Dynamometer measurements showed excellent interrater (r = .99) and intrarater (r = .97) reliability.

CONCLUSIONS

The degree of motor deficit quantitated with the dynamometer is strongly associated with the extent of neurological abnormality measured with the use of two standardized stroke scales. The computerized dynamometer rapidly measures motor function along a continuous, linear scale and produces a permanent recording of hand motor performance accessible for subsequent analyses.

Postischemic infusion of Cu/Zn superoxide dismutase or SOD:Tet451 reduces cerebral infarction following focal ischemia/reperfusion in rats

Oxygen-free radicals play a major role in neuronal cell injury following cerebral ischemia/reperfusion. The free-radical scavenging enzyme, Cu/Zn superoxide dismutase (SOD-1), ameliorates various types of brain injury resulting from temporary CNS ischemia. We have compared the cerebroprotective properties of human SOD-1 (hSOD-1) with a novel recombinant SOD-1 hybrid protein, SOD:Tet451, composed of hSOD-1 linked to the neuronal binding fragment of tetanus toxin (TTxC). Following 2 h of temporary middle cerebral artery occlusion, rats infused with equivalent activities of either hSOD-1 or SOD:Tet451 for the initial 3 h of reperfusion showed reductions in cerebral infarct volume of 43 and 57%, respectively, compared to saline-treated controls (P < 0.01). Serum hSOD-1 concentrations in rats receiving SOD:Tet451 were seven-fold higher than those in rats receiving the native enzyme. Animals treated with SOD:Tet451 also demonstrated an extended persistence of hSOD-1 in the bloodstream during drug washout as compared to animals given free enzyme. Immunohistochemical examination of brain sections from an SOD:Tet451-treated ischemic rat showed positive immunoreactivity in the ipsilateral cerebral cortex using either anti-TTxC or anti-human SOD-1 antibodies. Our results document that both hSOD-1 and SOD:Tet451 significantly reduce brain infarct volume in a model of transient focal ischemia/reperfusion in rats. Additionally, our findings suggest that the cerebroprotective effects of SOD-1 may be enhanced by neuronal targeting as seen with the hybrid protein SOD:Tet451.

Intracisternal basic fibroblast growth factor enhances functional recovery and up-regulates the expression of a molecular marker of neuronal sprouting following focal cerebral infarction

Focal cerebral infarction (stroke) due to unilateral occlusion of the middle cerebral artery in mature rats produces deficits in sensorimotor function of the contralateral limbs that recover partially over time. We found that biweekly intracisternal injection of basic fibroblast growth factor (bFGF; 0.5 microg/injection), a potent neurotrophic polypeptide, markedly enhanced recovery of sensorimotor function of the contralateral limbs during the first month after stroke without apparent adverse side effects. Immunostaining for growth-associated protein 43 (GAP-43), a molecular marker of axonal sprouting, showed a selective increase in GAP-43 immunoreactivity in the intact sensorimotor cortex contralateral to cerebral infarcts following bFGF treatment. These results show that bFGF treatment can enhance functional recovery after stroke, and that the mechanism may include stimulation of neuronal sprouting in the intact brain.

Time window of infarct reduction by intravenous basic fibroblast growth factor in focal cerebral ischemia

Basic fibroblast growth factor (bFGF) is a heparin-binding polypeptide with potent trophic and protective effects on brain neurons, glia and endothelia. In previous studies, we showed that intravenously administered bFGF reduced the volume of cerebral infarcts following permanent occlusion of the middle cerebral artery in rats. In the current study, we examined the time dependence of bFGF infusion on infarct reduction, and the effect of co-infusion of bFGF with heparin. We found a significant reduction in infarct volume when the bFGF infusion (50 microg/kg per h for 3 h) was begun up to 3 h, but not 4 h after the onset of ischemia. The infarct reducing effects of bFGF were not altered by co-infusion of heparin. These results are potentially important in light of the ongoing clinical trials of intravenous bFGF in acute stroke.

Delayed administration of basic fibroblast growth factor (bFGF) attenuates cognitive dysfunction following parasagittal fluid percussion brain injury in the rat

The present study evaluates the therapeutic effects of delayed administration of bFGF on cognitive dysfunction and histopathological damage following lateral fluid-percussion (FP) brain injury. Male Sprague-Dawley rats were trained to learn a visuospatial task in a Morris Water Maze (MWM) paradigm and then were anesthetized and subjected to either FP brain injury of moderate severity (2.5-2.8 atm, n = 32) or surgery without brain injury (n = 10). Twenty-four hours postinjury, an infusion cannula connected to a mini-osmotic pump was implanted into the area of maximal cortical injury to continuously infuse either bFGF (2.0 g) or vehicle for 7 days. Treatment with bFGF significantly attenuated posttraumatic memory dysfunction in the MWM at 8 days postinjury when compared to vehicle treatment (p < 0.05). The cortical lesion and significant cell loss in the ipsilateral CA3 region of the hippocampus, produced by FP injury, was not affected by bFGF treatment. However, immunohistochemical evaluation of glial fibrillary acidic protein revealed a trend toward increased astrocytosis in the injured cortex of bFGF-treated animals compared to vehicle-treated animals (p < 0.1). These results indicate that bFGF may be efficacious in attenuating cognitive dysfunction associated with traumatic brain injury.

bFGF ameliorates focal ischemic injury by blood flow-independent mechanisms in eNOS mutant mice

Genetically engineered mice deficient in the expression of type III nitric oxide synthase (NOS) [endothelial NOS (eNOS)] were used to decipher the importance of nitric oxide (NO)-dependent augmentation of regional cerebral blood flow (rCBF) to infarct volume reduction following basic fibroblast growth factor (bFGF) infusion during acute middle cerebral artery (MCA) occlusion. We have shown previously that intravenously administered bFGF reduces infarct volume following MCA occlusion in rats and that bFGF dilates cerebral pial arterioles by NO-dependent mechanisms. Halothane-anesthetized eNOS knockout and wild-type mice were subjected to permanent MCA occlusion by intraluminal filament for 24 h. bFGF (100 microg x kg(-1) x h(-1)) was infused intravenously for 2 h, beginning 15 min after the onset of occlusion. Infarct volume was reduced from 119 +/- 8 to 93 +/- 4 mm3 (22% reduction, P < 0.05) or from 102 +/- 9 to 77 +/- 6 mm3 (24% reduction, P < 0.05) in eNOS knockout or wild-type mice, respectively (means +/- SE; n = 10 per group), and neurological deficits were also significantly reduced. Although bFGF infusion caused a 27% increase in rCBF and a 17% reduction in vascular resistance in the infarct margin of wild-type animals as measured by laser Doppler flowmetry, bFGF did not enhance rCBF in the infarct margin of eNOS mutant mice. These data indicate that intravenous bFGF reduces infarct volume following focal ischemia by mechanisms that are largely blood flow independent.

Intravenous basic fibroblast growth factor decreases brain injury resulting from focal ischemia in cats

BACKGROUND AND PURPOSE

We tested the hypothesis that intravenous administration of basic fibroblast growth factor (bFGF) during 4 hours of permanent focal ischemia would affect acute brain injury.

METHODS

Halothane-anesthetized cats underwent left middle cerebral artery (MCA) occlusion for 4 hours. Control cats received diluent (n = 14). Experimental cats were treated with bFGF at a rate of 5 (n = 13), 50 (n = 13), or 250 microg/kg per hour (n = 9) intravenously beginning 60 minutes after initiation of ischemia and continuing until the end of the protocol.

RESULTS

As measured by the microsphere method, blood flow to ipsilateral caudate nucleus and ipsilateral inferior temporal cortex was decreased similarly during ischemia, before drug administration, in all groups. Likewise, there was no difference in blood flow to ipsilateral caudate nucleus or inferior temporal cortex as a result of bFGF administration during MCA occlusion. Triphenyltetrazolium-determined injury volume of the ipsilateral cerebral cortex (control, 40+/-7%; bFGF 5 microg/kg per hour, 22+/-5%; bFGF 50 microg/kg per hour, 26+/-7%; bFGF 255 microg/kg per hour, 23+/-6% of ipsilateral cerebral cortex; mean+/-SEM) was less in cats treated with bFGF. There was no difference among groups in injury volume to caudate nucleus (control, 29+/-8%; bFGF 5 microg/kg per hour, 29+/-8%; bFGF 50 microg/kg per hour, 21+/-7%; bFGF 250 microg/kg per hour, 32+/-7% of ipsilateral caudate nucleus). Somatosensory evoked potential amplitude decreased similarly (to <20% of baseline amplitude in all groups) during MCA occlusion and was not altered by bFGF administration. CONCLUSIONS; These data indicate that systemic administration of bFGF ameliorates acute injury in the cerebral cortex without increasing blood flow during focal ischemia in cats. Because bFGF afforded protection when administered after the onset of ischemia, bFGF may provide its beneficial effect by limiting progression of injury in ischemic border regions.

Delayed intravenous administration of basic fibroblast growth factor (bFGF) reduces infarct volume in a model of focal cerebral ischemia/reperfusion in the rat

Basic fibroblast growth factor (bFGF) is a potent neurotrophic and vasoactive peptide. Previous studies have shown that intraventricularly-administered bFGF reduces the size of cerebral infarcts following focal ischemia. In the current study, we tested the effects of intravenously-administered bFGF in a model of focal ischemia/reperfusion. The right middle cerebral artery of mature male Wistar rats was occluded by intraluminal suture. After 2 h of occlusion, the suture was removed and intravenous infusion of bFGF in vehicle (45 micrograms/kg/h) or vehicle alone was begun, lasting 3 h. Animals were weighed and evaluated neurologically until sacrifice 7 days after ischemia. The volume of cerebral infarcts was then determined by H and E staining and image analysis. We found a 40% reduction in infarct volume in bFGF- vs. vehicle-treated rats (n = 11 vs. 11, P < 0.05). Reduction in infarct volume was associated with improved neurological outcome and regained body weight in bFGF-treated animals (both P < 0.05). No change in blood pressure was found during bFGF treatment. These results show that the delayed intravenous administration of bFGF reduces infarct size in this model of focal ischemia/reperfusion. The mechanisms of infarct reduction may include direct cytoprotective and/or vasoactive effects.

Intracisternal basic fibroblast growth factor (bFGF) enhances behavioral recovery following focal cerebral infarction in the rat

Basic fibroblast growth factor (bFGF) is a potent neurotrophic agent that promotes neuronal survival and outgrowth. Previous studies have shown that bFGF, administered intraventricularly or intravenously before or within hours after ischemia, reduces infarct size and neurological deficits in models of focal cerebral ischemia in rats. In the current study, we tested the hypothesis that bFGF, administered at later time points after ischemia, might improve behavioral recovery without affecting infarct size. Mature Sprague-Dawley rats received bFGF (1 microgram/injection) or vehicle by biweekly intracisternal injection for 4 weeks, starting at 1 day following permanent proximal middle cerebral artery (MCA) occlusion. Animals were examined every other day using four different behavioral tests to assess sensorimotor and reflex function. At 4 weeks after ischemia, there was no difference in infarct volume between bFGF- and vehicle-treated animals. There was, however, an enhancement in the rate and degree of behavioral recovery among bFGF-treated animals, as measured by all four tests. There were no apparent side effects of bFGF treatment, except that bFGF-treated animals tended to recover body weight more slowly than did vehicle-treated animals following stroke. The mechanisms of enhancement of behavioral recovery by bFGF require further study, but may include protection against retrograde neuronal death and/or stimulation of neuronal sprouting.

Increased expression of basic fibroblast growth factor (bFGF) following focal cerebral infarction in the rat

Basic fibroblast growth factor (bFGF) is a polypeptide with potent trophic effects on brain neurons, glia, and endothelial cells. In the current study, we used Northern blotting, in situ hybridization, and immunohistochemical techniques to examine bFGF expression in brain following focal infarction due to permanent occlusion of the proximal middle cerebral artery in mature Sprague-Dawley rats. We found a four-fold increase in bFGF mRNA in tissue surrounding focal infarcts at 1 day after ischemia. In situ hybridization showed that this increase was found throughout several structures in the ipsilateral hemisphere, including frontoparietal, temporal, and cingulate cortex, as well as in caudoputamen, globus pallidus, septal nuclei, nucleus accumbens, and olfactory tubercle. Increased bFGF mRNA expression was associated with cells having the distinct morphological appearance of astroglia in these structures. Immunohistochemistry showed an increase in the size and number of bFGF-immunoreactive (IR) nuclei in these same structures, as well as a shift from nuclear to nuclear plus cytoplasmic localization of immunoreactivity, beginning at 1 day, and peaking at 3 days after ischemia. Double immunostaining identified bFGF-IR cells as astroglia in these structures. (An exception was the piriform cortex, in which both increased bFGF mRNA levels and increased bFGF-IR was found in neurons at 1 day after ischemia). Overall, the peak of increased bFGF expression preceded the peak in expression of the astroglial marker GFAP within the ipsilateral hemisphere. Increased bFGF expression may play an important role in the glial, neuronal, and vascular changes occurring after focal infarction.

Posttreatment with intravenous basic fibroblast growth factor reduces histopathological damage following fluid-percussion brain injury in rats

The purpose of this study was to determine whether treatment with intravenous basic fibroblast growth factor (bFGF) would protect histopathologically in a rat model of traumatic brain injury (TBI). Twenty-four hours prior to TBI, the fluid-percussion interface was positioned parasagittally over the right cerebral cortex. On the second day, fasted rats were anesthetized with 70% nitrous oxide, 1% halothane, and 30% oxygen. Under controlled physiological conditions and normothermic brain temperature (37-37.5 degrees C), rats were injured with a fluid-percussion pulse ranging from 1.6 to 1.9 atm. Rats were randomized into two groups where either bFGF (45 micrograms/kg/h) in vehicle (n = 7) or vehicle alone (n = 7) was infused intravenously for 3 h, beginning 30 min after TBI. Three days later, brains were perfusion-fixed for histopathological assessment and quantitative analysis of contusion volume and numbers of necrotic cortical neurons. In vehicle-treated animals, necrotic neurons were observed throughout the lateral cerebral cortex remote from the impact site. In addition, an intracerebral contusion was present in all rats at the gray-white interface underlying the injured cortical areas. Posttraumatic administration of bFGF significantly reduced the numbers of damaged cortical neuron profiles at several coronal levels and reduced the total number of damaged neurons (696 +/- 148 vs. 1,248 +/- 198, means +/- SEM), p < 0.05, ANOVA). In addition, contusion ares at several coronal levels as well as total contusion volume was significantly reduced (1.13 +/- 0.39 mm(3) vs. 3.18 +/- 0.81 mm(3), p < 0.05). These data demonstrate neuroprotection with intravenous bFGF infusion in the posttraumatic setting.

Petechial hemorrhages accompanying lobar hemorrhage: detection by gradient-echo MRI

Based on the pathologic observation that severe cerebral amyloid angiopathy is often accompanied by multiple petechial hemorrhages, we prospectively obtained gradient-echo MRI on 15 elderly patients with lobar hemorrhage on CT. Nine of the 15 demonstrated accompanying petechial hemorrhages restricted to the cortical or corticosubcortical regions. No similar lesions were present on gradient-echo MRI in 10 elderly control patients. These findings suggest that cerebral amyloid angiopathy might be neuroradiologically diagnosed and staged during life.

Hyperacute stroke: evaluation with combined multisection diffusion-weighted and hemodynamically weighted echo-planar MR imaging

PURPOSE

To evaluate acute stroke with conventional, multisection diffusion-weighted (DW), and hemodynamically weighted (HW) magnetic resonance (MR) imaging.

MATERIALS AND METHODS

The three MR imaging techniques were performed in 11 patients within 10 hours of the onset of acute hemiparesis. The volume of DW and HW abnormalities were compared with infarct volumes depicted at initial and/or follow-up MR or computed tomography (CT).

RESULTS

Findings at DW and HW imaging were abnormal in nine of the 11 patients, despite normal findings at initial CT and/or MR. In all nine patients, infarcts were depicted at follow-up CT or MR. The DW abnormality was generally smaller and the HW abnormality was generally larger than the infarct volume determined at subsequent imaging. In the two patients with normal findings at DW and HW imaging, symptoms resolved completely within 1-48 hours.

CONCLUSION

Different aspects of hyperacute cerebral ischemia are depicted at DW and HW imaging before infarction is depicted at conventional MR or CT. These techniques may improve stroke diagnosis and may contribute to advances in treatment.

Myocyte-specific enhancer binding factor 2C expression in gerbil brain following global cerebral ischemia

Myocyte-specific enhancer binding factor 2 (MEF2C) is a transcription factor expressed at high levels in brain. In this study, the distribution of MEF2C expression in brain was studied in normal adult gerbils and in adult gerbils subjected to 10 min of global cerebral ischemia. In normal animals, MEF2C-immunoreactivity and messenger RNA expression were detected in cortex, hippocampus, caudate-putamen, thalamus, hypothalamus, and amygdala. Within the hippocampus, MEF2C-immunoreactivity and MEF2C messenger RNA were found in interneurons scattered through the CA fields, a subset of which are parvalbumin-immunoreactive. MEF2C-immunoreactivity and MEF2C messenger RNA were also present in granule cells in the dentate gyrus. MEF2C-immunoreactivity was also detected in microglia in the hippocampus. After transient forebrain ischemia, CA1 pyramidal neurons, which are MEF2C-negative, degenerate whereas MEF2C-positive interneurons survive. Our results thus indicate that MEF2C is a marker for hippocampal neurons that are resistant to ischemia. It remains to be determined whether MEF2C plays a direct role in protecting the neurons that express it from ischemic injury. In addition, MEF2C-immunoreactivity is present in microglia, and, after ischemia, there were increased numbers of MEF2C-immunoreactive microglia in CA1, so MEF2C-immunoreactivity is a marker of both resting and activated microglia.

Delayed treatment with intravenous basic fibroblast growth factor reduces infarct size following permanent focal cerebral ischemia in rats

Basic fibroblast growth factor (bFGF) is a polypeptide that supports the survival of brain cells (including neurons, glia, and endothelia) and protects neurons against a number of toxins and insults in vitro. This factor is also a potent dilator of cerebral pial arterioles in vivo. In previous studies, we found that intraventricularly administered bFGF reduced infarct volume in a model of focal cerebral ischemia in rats. In the current study, bFGF (45 micrograms/kg/h) in vehicle, or vehicle alone, was infused intravenously for 3 h, beginning at 30 min after permanent middle cerebral artery occlusion by intraluminal suture in mature Sprague-Dawley rats. After 24 h, neurological deficit (as assessed by a 0- to 5-point scale, with 5 = most severe) was 2.6 +/- 1.0 in vehicle-treated and 1.5 +/- 1.3 in bFGF-treated rats (mean +/- SD; N = 12 vs. 11; p = 0.009). Infarct volume was 297 +/- 65 mm3 in vehicle- and 143 +/- 135 mm3 in bFGF-treated animals (p = 0.002). During infusion, there was a modest decrease in mean arterial blood pressure but no changes in arterial blood gases or core or brain temperature in bFGF-treated rats. Autoradiography following intravenous administration of 111In-labeled bFGF showed that labeled bFGF crossed the damaged blood-brain barrier to enter the ischemic (but not the nonischemic) hemisphere. Whether the infarct-reducing effects of bFGF depend on intraparenchymal or intravascular mechanisms requires further study.

Pretreatment with intraventricular basic fibroblast growth factor decreases infarct size following focal cerebral ischemia in rats

Basic fibroblast growth factor is a polypeptide with potent multipotential trophic effects on central nervous system cells, including neurons, glia, and endothelial cells. In particular, it promotes the survival of a wide variety of brain neurons in vitro, and protects these neurons against the effects of several neurotoxins, including excitatory amino acids, hypoglycemia, and calcium ionophore. Since lack of substrate delivery, excitatory amino acid toxicity, and calcium entry into cells appear to be important processes in neuronal death after ischemia, we tested the hypothesis that pretreatment with basic fibroblast growth factor limits infarct size in a model of focal cerebral ischemia in vivo. Mature male Long-Evans rats received either continuous intraventricular infusion of basic fibroblast growth factor (1.2 micrograms/day; with or without heparin, added to stabilize the growth factor) or vehicle alone for 3 days before focal ischemic infarcts were made in the right lateral cerebral cortex by permanent distal middle cerebral artery occlusion and temporary (45-minute) bilateral carotid occlusion. Intraoperative measurements of core temperature, arterial blood pressure and blood gases, blood glucose concentration, and hematocrit, and postoperative measurements of temperature revealed no differences among vehicle- versus basic fibroblast growth factor-treated animals. Twenty-four hours later, animals were killed, brains were removed and stained to visualize cortical infarcts, and infarct volume was determined by image analysis. Overall, we found a 25% reduction in infarct volume in basic fibroblast growth factor- (N = 25) versus vehicle-treated (N = 23) animals (p < 0.01). This reduction was not enhanced by the addition of heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Basic fibroblast growth factor dilates rat pial arterioles

Basic fibroblast growth factor (bFGF) is a polypeptide that promotes the survival and differentiation of brain neurons, glia, and endothelial cells. It has been shown recently that intravenously administered bFGF lowers blood pressure by systemic vasodilation; this effect is mediated, in part, by nitric oxide (NO)-dependent mechanisms. In the current study, we directly evaluated the effect of bFGF on pial arterioles of pentobarbital-anesthetized Sprague-Dawley rats (n = 18) using the closed cranial window technique. Basic FGF (5-200 ng/ml) produced dose-dependent vasodilation; maximal vessel diameter (approximately 120% of control) was reached at 100 ng/ml. No vasodilation was found when bFGF was heat inactivated, or preincubated with blocking antibody. Moreover, bFGF-induced vasodilation was attenuated by coadministration of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), consistent with an NO-dependent mechanism. These results suggest that bFGF may play an important role in the regulation of cerebrovascular tone and cerebral blood flow.

The clinical spectrum of cerebral amyloid angiopathy: presentations without lobar hemorrhage

Cerebral amyloid angiopathy is a common cause of spontaneous lobar hemorrhage in elderly patients. We discuss seven patients with amyloid angiopathy presenting without major lobar hemorrhage. The patients' presentations fell into two groups: recurrent transient neurologic symptoms and rapidly progressive dementia. The cases with transient episodes had a spread of symptoms to contiguous body areas during episodes. Each had evidence of small hemorrhage or subsequent large hemorrhage in the cortical location corresponding to the symptoms, suggesting petechial hemorrhage with focal seizure as the cause of the transient spells. Three cases of dementia developed with relatively rapid time courses, progressing from intact baseline to profound dementia in spans of a few days to 2 years. Pathologic abnormalities, in addition to amyloid angiopathy, included patchy white matter demyelination and tissue loss, petechial cortical hemorrhages, cortical infarctions, and a variable degree of neuritic plaques and neurofibrillary tangles. The clinical spectrum of cerebral amyloid angiopathy includes these two neurologic syndromes.

Delayed administration of basic fibroblast growth factor protects against N-methyl-D-aspartate neurotoxicity in neonatal rats

Neuroprotective effects of basic fibroblast growth factor (bFGF) (200 mu/kg i.p.) were examined at different time points following intrastriatal injection of N-methyl-D-aspartate (NMDA) in seven-day-old rats. When administered 0.5 h before intrastriatal NMDA injection, 200 micrograms/kg of bFGF significantly reduced NMDA-induced lesion by 47% as compared with vehicle treatment. Posttreatment with the same dose of bFGF at 0, 0.5 or 1 h after NMDA injection also significantly reduced those lesions by 45, 35 or 26%, respectively, while no neuroprotective effects was observed when administered at 2 or 4 h after NMDA injection.

Basic fibroblast growth factor protects against hypoxia-ischemia and NMDA neurotoxicity in neonatal rats

Basic fibroblast growth factor (bFGF) is a polypeptide that promotes neuronal survival and blocks excitatory amino acid (EAA) neurotoxicity in vitro at very low concentrations. In the present study, we examined whether systemically administered bFGF could prevent neuronal damage induced by either EAAs or hypoxia-ischemia in vivo. Neuroprotective effects were examined in a neonatal model of hypoxia-ischemia (unilateral ligation of the carotid artery followed by exposure to 8% oxygen for 1.5 h) and following intrastriatal injection of N-methyl-D-aspartate (NMDA) in 7-day-old rats. Intraperitoneal administration of a single dose of bFGF (50-300 micrograms/kg) 30 min before intrastriatal injection of NMDA showed a dose-dependent neuroprotective effect. Repeated doses of bFGF (100 micrograms/kg) both before and after intrastriatal NMDA injection produced a much greater significant protective effect than a single dose administered prior to the injection. Intraperitoneal injection of single dose of 100 micrograms/kg of bFGF 30 min before hypoxia-ischemia reduced neuronal damage by 38% (p = 0.14), while administration of bFGF at a dose of 100 micrograms/kg i.p. three times, 30 min before and 0 and 30 min after hypoxia-ischemia, significantly reduced neuronal damage by 64% (p = 0.004). Systemic administration of bFGF did not change body temperature for up to 3 h. These results show that systemic administration of bFGF can exert neuroprotective effects against both NMDA-induced excitotoxicity and hypoxia-ischemia in vivo.

Basic fibroblast growth factor protects striatal neurons in vitro from NMDA-receptor mediated excitotoxicity

Basic fibroblast growth factor (bFGF) promotes the survival and outgrowth of neurons. In this study the neuroprotective effects of bFGF were examined in 12-18-day-old cultured striatal neurons exposed to glutamic acid, kainic acid (KA), and quinolinic acid (QA), an N-methyl-D-aspartate (NMDA)-receptor agonist. Results showed that preincubation with bFGF (6 pM) from the day of plating significantly increased the survival of striatal neurons treated for 3 h with glutamate (3 mM) or QA (1 mM), but had little effect on KA (1 mM) induced toxicity. Moreover, maximum protection by bFGF against glutamate neurotoxicity was observed in cultures treated as little as 2 h before glutamate exposure. These results show that bFGF markedly protects striatal neurons from NMDA-receptor induced neurotoxicity.

Temporal, differential and regional expression of mRNA for basic fibroblast growth factor in the developing and adult rat brain

The expression of basic fibroblast growth factor (bFGF) mRNA and bFGF receptor mRNA was investigated in developing rat brain. In embryonic rat brain days 13-21 (E13-E21), an abundant 1.8 kb bFGF mRNA was detected. Expression of 1.8 kb bFGF mRNA was the highest at E17 to E19 and was relatively undetectable 20 days after birth. However, very little mitogenic activity was associated with prenatal brain. On the other hand, multiple bFGF mRNA species of 6.0, 3.7, 2.5, 1.8, 1.6, 1.4 and 1.0 kb were detected in total adult rat brain and a significant amount of mitogenic activity was present. Differential and spatial bFGF mRNA expression was found in different parts of developing rat brain. Embryonic hypothalamus was found to contain the 1.8 kb bFGF mRNA while the 6.0 kb bFGF mRNA transcript was predominant in adult hypothalamus. Adult pituitary and cortex transcribed the lower molecular weight mRNAs but not the 6.0 kb mRNA. Expression of high-affinity bFGF receptor (flg) mRNA was found to be temporally regulated. flg 4.3 kb mRNA expression was high in embryonic rat brain (E13-E19). There appears to be coordinate expression between the 1.8 kb bFGF mRNA and flg. These results suggest that the expression of basic FGF mRNA is complex since it is both temporally and differentially regulated with different species being expressed at different times in development.

Growth factor expression after stroke

Fibroblast growth factors are polypeptides with potent trophic effects on central nervous system cells. Both acidic and basic forms of fibroblast growth factor are found in the mammalian brain. We have examined the expression of these factors after focal brain injury or stroke. After infarction of the lateral cerebral cortex in the mature rat brain, we found a twofold to threefold increase during the first 3 weeks after stroke in levels of fibroblast growth factors in tissue surrounding infarcts. This increase persisted for at least 2 months and appeared mainly to be due to increased levels of basic, but not acidic, fibroblast growth factor. Because of its gliotrophic, angiogenic, and neuronotrophic properties, basic fibroblast growth factor may play an important role in the cascade of cellular reactions that contributes to wound healing and functional recovery after stroke.

Fibroblast growth factor (FGF) levels in the developing rat brain

Acidic and basic fibroblast growth factors (FGF) are polypeptides with potent multipotential trophic effects on central nervous system (CNS) glia, endothelial cells, and neurons. These factors are characterized by strong binding to heparin, and are commonly assayed by their mitogenic activity on Balb/c 3T3 cells in vitro. We found a marked (ca. 13-fold) increase in Balb/c 3T3 mitogenic activity in the developing rat brain from the embryonic stage to the third postnatal week. High levels were sustained in the mature brain. Most of the mitogenic activity from rat brain bound strongly to heparin-affinity columns, and was eluted at positions characteristic of acidic FGF (aFGF) and basic FGF (bFGF). The presence of aFGF and bFGF in eluted peaks was confirmed by immunoblotting techniques using specific anti-FGF sera. Heparin-affinity high performance liquid chromatography (HPLC) showed a proportionately greater increase in levels of aFGF than bFGF between the tenth and fortieth postnatal days. Increases in FGF levels during late embryonic and early postnatal stages of brain development may play an important role in the glial and capillary proliferation, as well as in the neuronal outgrowth and synapse formation that is occurring during this time. The differential rates of accumulation of aFGF vs bFGF suggest different physiological roles for these factors in the developing brain.

Protein fatty acid acylation in developing cortical neurons

Neuron-enriched cultures derived from embryonic day 17 rat cerebral cortex were incubated in the presence of [3H]myristic or [3H]palmitic acid. Analysis of radiolabeled proteins by two-dimensional gel electrophoresis and fluorography revealed extensive incorporation of fatty acids into a small number of neuronal proteins. The major acylated proteins had apparent molecular weights and isoelectric points as follows: 87,000, 4.3; 63,000, 4.4; 45,000, 4.4; and 20,000, 5.3. After labeling with [3H]myristic acid, the radioactivity associated with these proteins was identified as myristic acid, which was attached via an ester linkage. All four of the major acylated neuronal proteins were found to be membrane-bound and enriched in growth cones. By virtue of its molecular weight, isoelectric point, subcellular distribution, and peptide map, the 87-kilodalton polypeptide was shown to be equivalent to pp80, a phosphoprotein that has been described in developing and mature synaptic terminals. The 45-kilodalton acylated protein also appears to coincide with another growth cone phosphoprotein, pp40. Acylation may serve as a mechanism to regulate the function of these proteins, or may play a role in directing them to the nerve terminal membrane.

Localization of the growth-associated phosphoprotein GAP-43 (B-50, F1) in the human cerebral cortex

The growth-associated phosphoprotein GAP-43 is a component of the presynaptic membrane that has been linked to the development and functional modulation of neuronal connections. A monospecific antibody raised against rat GAP-43 was used here to study the distribution of the protein in cortical and subcortical areas of the human brain. On Western blots, the antibody recognized a synaptosomal plasma membrane protein that had an apparent molecular weight and isoelectric point similar to GAP-43 of other species. In brain tissue reacted with the antibody, the heaviest immunoreactivity was found in associative areas of the neocortex, particularly within layers 1 and 6, in the molecular layer of the dentate gyrus, the caudate putamen, and the amygdala. In contrast, primary sensory or motor regions of the cortex, portions of dorsal thalamus, and cerebellum showed only light staining. Staining was generally confined to the neuropil, which showed punctate labeling, whereas most neuronal somata and fiber bundles were unreactive. The pronounced variations in GAP-43 immunostaining among various areas of the human brain may reflect different potentials for functional and/or structural remodeling.

Partial purification and characterization of a neurite-promoting factor from the injured goldfish optic nerve

We have partially purified and characterized a neurite-promoting factor derived from the injured goldfish optic nerve (ON). This factor is secreted into conditioned media (CM) by the injured, but not intact goldfish ON, and has potent outgrowth-promoting effects on neurons of the embryonic mammalian brain. Based on its elution properties on ion-exchange and gel-filtration chromatography, this factor appears to be an acidic protein of Mr ca. 26 kilodaltons (kDa) that is distinct from previously characterized growth factors with described effects on mammalian CNS neurons.

Increased activity and phase delay in circadian motility rhythms in geriatric depression. Preliminary observations

Locomotor activity levels and rhythms of eight hospitalized geriatric unipolar depressed patients (DSM-III criteria) were compared with those of eight healthy elderly controls in a similar environment. Activity was measured using a wrist-worn electronic activity monitor with solid-state memory. Depressed patients had a 29% higher mean total 24-hour activity level, with no change in circadian amplitude or frequency. Daily peak activity (acrophase) averaged 2.05 hours later in depressed patients, with no overlap between the groups. The degree of phase delay correlated significantly with the 4 PM postdexamethasone serum cortisol level. These tentative findings suggest that elderly unipolar depressed patients have prominent chronobiological disturbances in the modulation of activity levels and possibly other physiological processes. These differ strikingly from reported disturbances in younger or bipolar depressed patients.

Increased basic fibroblast growth factor (bFGF) immunoreactivity at the site of focal brain wounds

Basic fibroblast growth factor (bFGF) is a polypeptide found within the CNS with potent effects on the survival and proliferation of CNS glia and endothelial cells, and on the survival and outgrowth of CNS neurons. Immunohistochemical methods were used to examine relative changes in the levels and distribution of bFGF following focal brain injury. Two monospecific antisera to bFGF were used to immunostain intact mature rat brain, and brain in which a focal mechanical lesion had been made in the dorsolateral cerebral cortex one week previously. In the intact brain, staining was localized primarily in neuronal cell bodies, especially in limbic structures. In injured brain, a marked increase of bFGF immunoreactivity was found at the borders of lesions, localized to the dense accumulation of cells, many of which resembled 'reactive' astroglia. Such increases in local bFGF concentrations may contribute to the cascade of cellular changes--including glial and capillary proliferation, and neural sprouting--that follows focal brain injury.

Comparison of MRI and CT scans in a group of psychiatric patients

The authors compared the results of computerized tomography (CT) and magnetic resonance imaging (MRI) scans of 16 psychotic patients with various diagnoses whose neurologic examinations suggested structural brain abnormalities. Blind readings showed a high concordance of findings, including ventricle-to-brain ratios, although MRI appeared superior in visualizing midline structures and identifying atrophic changes. Because it requires no ionizing radiation, MRI allows multiple studies of the same patient, study of family members, and recruitment of unbiased samples of control subjects. Use of MRI may help address questions regarding the specificity and prevalence of brain abnormalities observed with CT in psychotic patients.

A factor from the injured lower vertebrate CNS promotes outgrowth from human fetal brain neurons

Unlike mammals, lower vertebrates retain the capacity to regenerate damaged central nervous system (CNS) pathways throughout life. In previous studies, we have used the goldfish optic nerve (ON) as a model for CNS regeneration, and found that the injured goldfish ON selectively secretes a factor that promotes process outgrowth of cultured neurons, including neurons of the developing rodent CNS. In the current study, we found that a factor similarly obtained from the injured goldfish ON also has potent outgrowth-promoting effects on cerebrocortical neurons of the fetal human brain, and that these effects are dependent on the age of fetal neurons. This factor appeared to be a protein of mol. wt. greater than 12,000, and was associated with a distinctive morphology of neurite outgrowth. The neurite-promoting factor from the injured goldfish ON may be homologous to factors within the developing human brain.

Anatomical distribution of the growth-associated protein GAP-43/B-50 in the adult rat brain

GAP-43 (B-50,F1,pp46) is a neuron-specific phosphoprotein that has been implicated in the development and modulation of synaptic relationships. Although most neurons cease expressing high levels of GAP-43 after the completion of synaptogenesis (Jacobson et al., 1986), certain brain regions continue to have considerable amounts of the protein throughout life (Oestreicher et al., 1986); in at least one such area, the phosphorylation of the protein has been linked with the events that underlie synaptic potentiation (Lovinger et al., 1985). In this study, we used the indirect immunoperoxidase method to map the distribution of GAP-43/B-50 in the brains of 8 adult rats with 2 different antibodies: a monospecific, polyclonal antibody prepared in sheep against the purified protein and an affinity-purified IgG prepared in rabbits. Specific immunoreactivity was found primarily in the neuropil and followed a generally increasing caudal-to-rostral gradient along the neuraxis. Densest staining occurred in layer I of the cortex, the CA1 field of the hippocampus, and in a continuum of subcortical structures that included the caudate-putamen, olfactory tubercle, nucleus accumbens, bed nucleus of the stria terminalis, amygdala, and medial preoptic area-hypothalamus. In the brain stem, staining was seen in the central gray and in ascending visceral relay nuclei, but was essentially absent in areas related to ascending somatosensory information (e.g., the cochlear nuclei or vestibular complex) and motor control (e.g., nucleus ruber or the motor nuclei of the cranial nerves). Staining in dorsal thalamus was likewise modest in most somatosensory and somatomotor relay nuclei, but dark in certain other structures (e.g., mediodorsal nucleus, lateral complex). This distributional pattern raises the question of whether synapses in all areas containing high levels of GAP-43/B-50 are capable of undergoing functional plasticity, or whether the protein may function in some of these areas in some other capacity (e.g., general signal transduction).