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Biomedical subjects

D G Stein

Publications and source records attributed to D G Stein.

At least 37 records · Page 2Linked to original sources
PubMed1997

Astrocytes grafted into rat nucleus basalis magnocellularis immediately after ibotenic acid injection fail to survive and have no effect on functional recovery.

In order to determine if the "trophic" properties of astrocytes makes them appropriate for use as a therapeutic agent to excitotoxic brain damage, adult male rats received grafts of cultured cerebral cortical astrocytes into the NBM immediately after infusion of ibotenic acid into the same structure. Twenty four hours after grafting and every other day for 11 days post surgery, the animals were tested for locomotor activity and habituation in an open field. Animals with NBM lesions had significantly reduced rearing activity as compared to counterparts with no lesions. Nine days after surgery, rats with NBM lesions and astrocyte grafts were as impaired in the acquisition of passive avoidance (PA) as their untreated counterparts. All animals with ibotenic lesions were impaired on PA retention compared to rats with no lesions. There was no difference between animals that had received grafts and those that had not. Fourteen days after grafting, all brains were processed for Nissl stain, acetylcholinesterase (AChE) histochemistry, GFAP immunocytochemistry, and bisbenzamide fluorescent microscopy. Decreases in the number of neurons in the NBM as well as decreases in the density of AChE staining in the ipsilateral cortex (the area of innervation of the NBM cholinergic neurons) was evident in all animals with NBM lesions. In addition, a large number of host reactive astrocytes were seen within the NBM, its vicinity, and in the ipsilateral neocortex. Grafted astrocytes survived and integrated into the host tissue when they were grafted into the brain of intact animals but no living grafted astrocytes were found in animals injected with ibotenate. In this latter case, two weeks after grafting, instead of surviving astrocytes only fluorescent tissue 'masses' were seen in the NBM, surrounded by a cavity. Grafted astrocytes did not have any effect on the extension of the lesion caused by ibotenic acid infusion. These results suggest that the concentration of ibotenic acid used to injure the NBM killed not only the host cholinergic neurons but also the grafted astrocytes. The failure of astrocytes to ameliorate the behavioral deficits caused by ibotenic acid lesions of the NBM may be due to the ibotenic acid creating a lethal environment for the grafted and freshly dissociated, cultured astrocytes.

Acetylcholine↗
PubMed1996

Intraseptal injections of NGF attenuates edema formation following septal lesions in the rat.

Rats with electrolytic lesions of the medial septum received a single intraseptal injection of either nerve growth factor (NGF) or saline immediately following surgery. The formation of edema was then assessed at five time points following the lesions to the septum: 6 h, 1 day, 2 days, 3 days, and 5 days. Edema formation was detected as early as 6 h in both groups. However, by 2 days following surgery, the NGF treated rats had significantly less edema formation than their lesion alone counterparts. These results can be taken to indicate that NGF may alter locally mediating events that limit the effects of reactions associated with the inflammation of damaged tissue.

Animals↗
PubMed1996

Progesterone rapidly decreases brain edema: treatment delayed up to 24 hours is still effective.

Cerebral edema is a serious side effect of traumatic brain injury. We have previously established that progesterone injections, initiated within 1 h after cortical contusion injury, reduced edema when assessed 3 days later. To determine how rapidly progesterone can reduce edema, male and female rats were given the hormone 1 h after damage to the medial frontal cortex, and edema levels were assessed between 2 h and 7 days postinjury. Progesterone decreased edema with 6 h of the injury and continued to be effective for the duration of treatment. In addition, we assessed whether progesterone injections are effective when delays are imposed between injury and initiation of treatment. Male and female rats received progesterone after postinjury delays 6, 24, or 48 h. Progesterone was effective in reducing edema when treatment was delayed until 24 h after injury.

Animals↗
PubMed1996

A reliable and sensitive enzyme immunoassay method for measuring 8-isoprostaglandin F2 alpha: a marker for lipid peroxidation after experimental brain injury.

The objectives of this study were to determine (1) if levels of 8-isoprostaglandin F2 alpha (8-isoPGF2 alpha), a non-enzymatically produced prostaglandin, were increased after cortical contusion and (2) if enzyme immunoassay (EIA) could be used to quantify 8-isoPGF2 alpha levels. 24 h after the contusion there was a significant rise in 8-isoPGF2 alpha compared to control levels. The levels returned to baseline by 72 h postinjury. The results show that this EIA method is a reliable and sensitive technique for measuring brain lipid peroxidation.

Animals↗
PubMed1996

Infusion of glial maturation factor-beta reduces behavioral deficits after caudate nucleus injury in rats.

Adult rats with bilateral thermal lesions of the caudate nuclei (CN) show severe learning and memory deficits. The present study was designed to test the effects of an astroglial stimulating growth factor in this behavioral model. Immediately after receiving lesions of the CN, experimental subjects received an injection of one of three doses of glial maturation factor-beta (GMF-beta) directly in the lesion site. All subjects were then tested for twenty days on an active avoidance spatial alternation task. The behavioral recovery of the three groups of experimental animals was compared to that of animals having received the same brain damage and administration of a control substance (lesion controls), and to that of animals receiving a sham operation and no treatment (shams). The beneficial effects of administration were evident in the group of experimental animals receiving the lowest dose of GMF-beta. The performance of animals in this group was indistinguishable from that of the shams, and was significantly better than that of the lesion controls. The results suggest a behavioral role of GMF-beta which, in an in vitro system, is known to be a growth regulator of astroglial cells.

Animals↗
PubMed1995

A single intraseptal injection of nerve growth factor facilitates radial maze performance following damage to the medial septum in rats.

Rats were trained on a radial maze and then given electrolytic lesions of the MS followed by a single intraseptal injection of 5 micrograms of NGF. Three days later they were re-tested on the maze. They were also post-operatively tested for hyperemotionality. MS lesions severely impaired performance on the radial maze and produced increased emotionality. MS lesions also produced a general decrease in hippocampal high affinity choline transport and acetylcholinesterase staining, which was not affected by NGF administration. NGF treatment ameliorated the behavioral deficit in the radial maze but had no effect on the hyperemotionality. In order to determine whether the NGF was working to restore previously learned spatial abilities, the type of learning strategy used by the animals was also assessed. NGF treatment did not restore previously learned spatial strategies but facilitated recovery of alternative learning strategies. The reduction in cognitive deficit was also paralleled by reduced ventricular enlargement in the NGF treated rats. The present results suggest that a single injection of NGF can produce a long-lasting improvement on a cognitive task and reduce some of the injury-induced, secondary reactive changes that occur following electrolytic MS lesions.

Analysis of Variance↗
PubMed1995

Effects of unilateral entorhinal cortex lesion and ganglioside GM1 treatment on performance in a novel water maze task.

Transient deficits have been reported after unilateral entorhinal cortex (EC) lesion. To determine whether there is a more persistent deficit, adult male Sprague-Dawley rats with electrolytic or sham lesions of the left entorhinal cortex were examined on acquisition of a modified working memory task in the Morris water maze. This delayed matching-to-sample task, with a 1-h intertrial interval, reveals a significant deficit in total distance to platform in both presentation (Trial 1) and matching (Trial 2) in the rats with entorhinal lesions. We have also found that this test can be used to assess significant deficits in perseveration (repeated nonproductive movement) in rats with entorhinal lesions. The deficits can be seen up to 16 days postinjury. Administration of ganglioside GM1 resulted in a moderate improvement in performance in both water maze measures analyzed. All groups (sham operated, lesion with saline treatment, and lesion with ganglioside GM1 treatment) were given three other tests, which were used to evaluate possible contributing factors to deficient water maze performance. A one-trial test for exploration of novel objects revealed no significant, simple working memory deficit in any group. Plus maze testing, to assess possible differences in levels of anxiety or increased activity as a component of water maze performance, also revealed no differences in the three groups. All groups were also similar in motor activity, shown by monitoring of activity levels. The worsened water maze performance observed in rats with EC lesion may be related to deficits in working memory ability within the framework of acquisition of a more complex spatial learning task.

Animals↗
PubMed1995

A reliable and sensitive method for non-radioactive northern blot analysis of nerve growth factor mRNA from brain tissues.

This report describes a sensitive, rapid and reproducible protocol for non-isotopic Northern blotting analysis. Church buffer and probes labeled with digoxigenin (DIG) were used for studying the expression of nerve growth factor (NGF) in the rat brain. Using the described method, NGF cRNA probe was hybridized to blotted RNA and the results were compared to Northern blot obtained using the method recommended by the manufacturer (Boehringer Mannheim). Comparison revealed that the blot treated with Church buffer detected at least 10-fold more NGF mRNA as compared to blot hybridized with formamide buffer. In summary, we have developed an optimal hybridization protocol to perform non-radioactive Northern blot analysis using antisense RNA as a probe. This method allowed us to detect the specific low-abundant mRNA and analyze the expression of neurotrophic factors in the rat brain.

Animals↗
PubMed1995

Blood-brain barrier breakdown and edema formation following frontal cortical contusion: does hormonal status play a role?

The present experiment was designed to evaluate and correlate the time course of blood-brain barrier (BBB) integrity and cerebral edema in adult male rats given medial frontal cortex contusions. The effect of sex hormones on BBB integrity in the same injury model was also examined, because previous work has shown that progesterone can reduce cerebral edema (Roof et al., 1993). BBB breakdown was assessed by Evans blue extravasation and albumin immunostaining while edema formation was measured by the wet weight dry weight technique. These processes were examined beginning 2 h and continuing up to 10 days after injury. Our findings show that medial frontal contusion in rats produces changes in cerebral water content and opening of the BBB that endures at least 7 days postinjury. Although pseudopregnancy has been shown to reduce cerebral edema at day 1 postinjury, we did not find any evidence that this hormonal state is associated with BBB repair.

Animals↗
PubMed1994

Progesterone facilitates cognitive recovery and reduces secondary neuronal loss caused by cortical contusion injury in male rats.

The ability of progesterone to reduce the cerebral edema associated with traumatic brain damage first became apparent when we observed that males had significantly more edema than females after cortical contusion. In addition, edema was almost absent in pseudopregnant female rats, a condition in which progesterone levels are high relative to estrogen. Progesterone injections given after injury also reduced edema and were equally effective in both males and females. The present experiment was done to determine if the progesterone-induced reduction in edema could also prevent secondary neuronal degeneration and reduce the behavioral impairments that accompany contusion of the medial frontal cortex. Progesterone-treated rats were less impaired on a Morris water maze spatial navigation task than rats treated with the oil vehicle. Progesterone-treated rats also showed less neuronal degeneration 21 days after injury in the medial dorsal thalamic nucleus, a structure that has reciprocal connections with the contused area.

Analysis of Variance↗
PubMed1994

Bilateral frontal cortical contusion in rats: behavioral and anatomic consequences.

The purpose of this study was to develop a bilateral model of frontal cortical contusion in the rat that would demonstrate reproducible deficits typically found after frontal lobe injury in humans. We used a pneumatically controlled cortical impactor to create bilateral contusions of the medial prefrontal cortex (PFC) in adult male Sprague-Dawley rats. Cognitive, neurologic, physiologic, and histopathologic measures were used to evaluate changes caused by the injury. The cognitive task employed the Morris water maze (MWM). Contused rats performed worse than sham-operated controls on measures of time taken to find a submerged platform, distance to the platform, and swim strategy. Neurologic measures revealed impairments of tongue mobility and transient deficits of forelimb placing. Body weights of the contused rats were chronically reduced with respect to controls, indicating that cortical contusion produces disruption in homeostasis. All rats given bilateral PFC contusions developed marked necrotic cavities at the site of impact. The borders surrounding the cavities were heavily lined with astrocytes and ameboid microglia. There was subcortical gliosis in the medial caudate that extended throughout the rostral-caudal length of the caudate-putamen and into the mediodorsal (MD) and ventrolateral (VL) nuclei of the thalamus. The thalamus was also the site of distal transneuronal degeneration. In both the MD and the VL, there was significant neuronal loss in the contused rats as compared with sham-operated controls. This method of bilateral cortical contusion demonstrates clear, reproducible results that would be required for the development of future pharmacologic therapies designed to promote functional recovery.

Animals↗
PubMed1993

Gender-specific impairment on Morris water maze task after entorhinal cortex lesion.

After unilateral entorhinal cortex lesion, deficits on a working spatial memory Morris water maze task were examined in male and female rats to determine if gender differences exist in response to hippocampal deafferentation. Brain-damaged males showed a persistent water maze deficit that persisted throughout the 10 days of testing. Brain-damaged females did not. The performance of the injured females was only slightly impaired relative to sham males and females, and was significantly better than males with EC damage. This lack of a water maze deficit in lesion females is hypothesized to be due either to gender differences in sprouting responses or to a more flexible use of multiple cues by females relative to males.

Animals↗
PubMed1993

Gender influences outcome of brain injury: progesterone plays a protective role.

The contributions of gender and gonadal hormones in the cascade of events following brain injury are largely unexplored. We measured cerebral edema following cerebral contusion in rats under three hormonal conditions to address this issue. Normally cycling females exhibited significantly less edema than males, and pseudopregnant females were virtually spared from post-injury edema. Subsequent studies of ovariectomized females, with or without hormone treatment, indicated that the reduction of cerebral edema was associated primarily with the presence of circulating progesterone. We conclude that progesterone has a protective effect on the brain following traumatic injury.

Animals↗
PubMed1993

Comparison of GM1 ganglioside, AGF2, and D-amphetamine as treatments for spatial reversal and place learning deficits following lesions of the neostriatum.

These experiments tested the effectiveness of parenterally administered gangliosides and amphetamine as treatments for spatial learning deficits caused by bilateral lesions of the neostriatum. In Expt. 1, rats were tested postsurgically for 30 days on a shock-avoidance, spatial reversal task. Treatments of gangliosides (GM1 at 30 mg/kg, and AGF2 at 20 mg/kg and 30 mg/kg) and D-amphetamine (2 mg/kg) significantly decreased lesion-induced learning deficits on this task, while treatments of 10 mg/kg AGF2 and the combination of GM1 (30 mg/kg) and D-amphetamine (2 mg/kg) were ineffective. In Expt. 2, rats were given bilateral neostriatal lesions and treated with GM1 (30 mg/kg), AGF2 (20 mg/kg) or D-amphetamine (2 mg/kg) and tested postsurgically for 5 days on a place learning task in the Morris water maze. Only the GM1-treated rats showed a reduction in lesion-induced place learning deficits on this task. Since in both experiments, cell counts near the area of the lesion revealed no differences among any of the brain-damaged groups, it was suggested that the treatments exert their behavioral effects by biochemically activating spared neurons, independent of any ultimate effects they may have on neuronal survival.

Adenosine Monophosphate↗
PubMed1993

Perfluorochemical reperfusion yields improved myocardial recovery after global ischemia.

Reperfusion injury remains a limiting factor in extending ischemic storage time for human heart transplantation. In this study, initial myocardial reperfusion with an oxygenated perfluorochemical (Fluosol) was investigated as a means of limiting such injury. Neonatal piglet hearts were arrested with crystalloid cardioplegia, excised, and stored for 12 hours in saline solution at 0 degrees C. Initial reperfusion (10 minutes) was either with whole blood (n = 6), unmodified perfluorochemical (n = 8), or aspartate/glutamate-enriched perfluorochemical cardioplegia (n = 6), and was followed by an additional 40 minutes of whole blood perfusion. Functional evaluation was then completed, and left ventricular biopsy specimens were taken. A control group (n = 7) was evaluated without an intervening period of ischemia. At a left ventricular end-diastolic pressure of 9 mm Hg, hearts stored in whole blood cardioplegia developed a left-ventricular stroke work index of 3.8 +/- 2.3 x 10(3) erg/g (mean +/- standard error of the mean). Under the same conditions, perfluorochemical-reperfused hearts achieved a stroke work index of 14.6 +/- 1.3 x 10(3) erg/g, significantly greater than that of the whole blood group (p < 0.001). Stroke work index for hearts reperfused with aspartate/glutamate-enriched perfluorochemical cardioplegia was 19.8 +/- 1.6 x 10(3) erg/g, significantly increased over that of the nonenriched perfluorochemical group (p < 0.01) and not different from values obtained in controls (19.2 +/- 0.8 x 10(3) erg/g).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1993

Unilateral cortical contusion injury in the rat: vascular disruption and temporal development of cortical necrosis.

Cerebrovascular disruption and cortical pathology resulting from either moderate (M-TBI) or severe (S-TBI) traumatic brain injury produced by a pneumatically-driven cortical contusion device were assessed in adult male rats sacrificed at 6 and 24 h or 8 and 30 days after injury to the right sensorimotor cortex. Epidural, subdural, subarachnoid, petechial (cortex and corpus callosum), and/or intraventricular hemorrhage was present in all animals, more extensively and severely following S-TBI. At 6 or 24 h after TBI, acidophilic (acid fuchsin-positive) neurons were numerous and widespread (S-TBI > M-TBI) in the ipsilateral contused cortex. By 8 days few acidophilic neurons were present in peri-impact regions of the ipsilateral neocortex, and none were detected in cortex 30 days postinjury. Both M-TBI and S-TBI groups had enlarged ipsilateral cortical volumes (edema) at 6 and 24 h post-contusion. Eight and 30 days after injury the mean volume of cortical necrosis was significantly larger in S-TBI than in M-TBI rats, and cortical necrosis in both TBI conditions increased between 8 to 30 days postinjury. These results indicate that this pneumatically-driven contusion device produces reliable and consistent primary and secondary cortical histopathology, the extent of which is related to the severity of initial injury.

Animals↗