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W J Freed

Publications and source records attributed to W J Freed.

At least 19 recordsLinked to original sources
PubMed1992

Effects of adrenal medulla grafts on plasma catecholamines and rotational behavior.

The mechanisms by which adrenal medulla grafts influence the function of host brains in animal models of Parkinson's disease are unclear. To explore this issue, fragments of adrenal medulla or sciatic nerve were transplanted into the lateral ventricle of bilaterally adrenalectomized (ADX) or sham-ADX rats with unilateral 6-hydroxydopamine lesions of the substantia nigra. Additional control group received sham-transplantation surgery. Behavioral effects of these procedures were tested following administration of apomorphine, amphetamine, or nicotine. Plasma catecholamines were measured before and after transplantation surgery. In both ADX and sham-ADX rats, adrenal medulla grafts produced greater decreases in apomorphine-induced rotational behavior than did sciatic nerve grafts or sham-transplanted groups. Decreases in rotation were smaller in ADX than in sham-ADX animals, regardless of graft treatment. Plasma catecholamines increased after transplantation surgery in each of the sham-ADX groups, regardless of graft type. Increases in plasma dopamine concentrations were associated with decreases in rotational behavior. Five months after transplantation, grafted chromaffin cells demonstrated catecholamine fluorescence, tyrosine hydroxylase (TH) and chromogranin A immunoreactivities, and expression of TH mRNA. It is concluded that adrenal medulla grafts produce decreases in apomorphine-induced rotation through a combination of two independent effects. One is a specific effect of adrenal medulla grafts. The second is a nonspecific effect that requires an intact adrenal gland and may be related to increases in plasma catecholamine concentrations.

Adrenal Medulla↗
PubMed1992

L1 substrate enhances outgrowth of tyrosine hydroxylase-immunoreactive neurites in mesencephalic cell culture.

We have evaluated neurite outgrowth from mesencephalic tyrosine hydroxylase-positive neurons grown in vitro on different substrates. Cultures of ventral mesencephalon from rat embryos (E13) were plated on plastic dishes coated with the following substrates: L1, L2/HNK-1 "residual" (mainly J1/160 but also tenascin), MAG antigens from mouse brains, laminin, fibronectin, poly-L-lysine, RGD peptide, and plastic alone. After 3, 4, and 6 days in vitro, the cultures were stained using an antibody against tyrosine hydroxylase (TH), and the length of TH-positive neurites was measured by computer-assisted image analysis in a double-blind fashion. L1 antigen had a significant positive effect on neurite outgrowth compared to the other substrates studied. Laminin and fibronectin were also favorable substrates. In cultures treated with cytosine arabinoside to prevent mitoses and glial proliferation, the positive effect of L1 was abolished, but laminin still had a stimulatory effect. These data indicate that L1 may be indirectly involved in differentiation or axonal elongation of substantia nigra dopaminergic neurons and suggest a complex effect involving both neurons and glia on dopaminergic neurite development.

Animals↗
PubMed1992

Human cortical neuronal cell line (HCN-1): further in vitro characterization and suitability for brain transplantation.

The human neuronal cell-1 (HCN-1) line has recently been established. Under favorable conditions, these cells differentiate into mature neuronal phenotypes. Here we report on further characterization of these cells. Cultured HCN-1 cells express fibronectin immunoreactivity and grow well on fibronectin substrate but do not respond to human bFGF. In the undifferentiated state, some HCN-1 cells show MHC class I antigen expression. After differentiation, HCN-1 cells and their processes are MHC class I negative. On the other hand, interferon-gamma stimulation enhances MHC class I expression but does not induce MHC class II immunoreactivity. Our in vitro data indicate that HCN-1 cells express mixed characteristics, including both neuronal and mesenchymal markers, and are consistent with the suggestion that the HCN-1 cell line resembles an immature neuroepithelial cell precursor with a complex origin. One possible application of the use of the HCN-1 cells includes intracerebral transplantation. We also examined the survival of dissociated HCN-1 cells implanted into rat brain parenchyma. The host animals were not immunosuppressed. Despite expression of MHC class I antigens, small clusters of HCN-1 cells survived in the rat brain. These xenografts did not induce distinct immunological responses within the host brain tissue. Surviving HCN-1 cells demonstrated similar features to those observed in culture. Our preliminary results suggest that the HCN-1 cell line would be suitable for intracerebral transplantation in primates or humans. However, it may be that short-term host immunosuppression or addition of HCN-1 cell differentiation factors would be beneficial for enhanced cell survival.

Animals↗
PubMed1991

BN rats do not reject F344 brain allografts even after systemic sensitization.

Embryonic brain tissue allografts under many circumstances survive transplantation into the brain. It is generally believed that such grafts will not survive if the host animal is systemically sensitized, by skin grafting or other means, to major histocompatibility complex (MHC) antigens of the donor animal. We have found that F344 brain grafts survive in BN hosts even when the host is systemically sensitized to F344 tissue. Embryonic cerebral neocortex from F344 donors was transplanted into BN host rats (n = 95). Subsequently, the host rats were systemically sensitized with donor skin (n = 25), brain tissue (n = 41), or spleen cells (n = 6) and compared with a control group of rats consisting of allografts with no sensitization or sham procedures (n = 23). Rejection of the transplants in BN rat hosts was not provoked by any of the sensitization methods tested. Minor immunological responses that did not result in rejection were, however, present in many host animals. We did not observe infiltration of W3/13+ T cells and OX8+ cytotoxic lymphocytes in any of the groups. Nevertheless, substantial infiltrations of OX6+ antigen-presenting cells and W3/25+ helper T cells were present. There was also an extensive enhancement of MHC class I immunoreactivity in parts of the grafted tissue developing within the third ventricle, but not for the same type of graft in the lateral ventricle. This increase of MHC class I expression was not accompanied by infiltration of cytotoxic T cells. Our findings thus suggest that neural graft rejection depends on general genetic susceptibility to immune reactions, particularly experimental allergic encephalomyelitis and not only on disparity between donor and host antigens encoded by the MHC. Moreover, enhancement of MHC class I and class II expression within transplanted tissue does not predict graft rejection.

Animals↗
PubMed1991

Brain grafts and Parkinson's disease.

In animal models, grafts derived from several different tissues, principally fetal substantia nigra and adrenal medulla from young adults, have been found to be effective in alleviating some of the manifestations of lesions of the substantia nigra. It has been suggested that these grafts function by diffusely secreting dopamine, by exerting trophic effects on the host brain, or by producing a new innervation of the host corpus striatum. Evidence for each of these modes of action is briefly reviewed. Several brain tissue transplantation techniques have been described. Each of these techniques has significant limitations in animal models. The significance of these limitations for human application is described, and possibilities for improving the efficacy of brain tissue transplantation in animal models and for human application are discussed.

Adrenal Medulla↗
PubMed1991

Applications of immortalized cells in basic and clinical neurology.

Immortalized cell lines can serve as model systems for studies of neuronal development and restoration of function in models of neurological disease. Cell lines which result from spontaneous or experimentally-induced tumors have been used for these purposes. More recently, the techniques of genetic engineering have resulted in the production of cell lines with specific desired characteristics. This has been accomplished by insertion of a desired gene into a pre-existing immortal cell or by immortalizing primary cells. The production of immortal cell lines using temperature-sensitive immortalizing genes offers an additional method of controlling gene expression, and thereby controlling cell proliferation and differentiation. In the nervous system, these techniques have produced immortal cell lines with neuronal and glial properties.

Cell Line↗
PubMed1991

A clinical trial of nifedipine in schizophrenia and tardive dyskinesia.

Effects of the dihydropyridine calcium channel inhibitor nifedipine on chronic schizophrenia and tardive dyskinesia were studied in an 8-week double-blind crossover trial. Four of the ten patients had tardive dyskinesia, and three of these were not receiving neuroleptics. No effects on symptoms of chronic schizophrenia were found using Psychiatric Symptom Assessment Scale ratings. In the four patients with tardive dyskinesia, an average improvement in total Abnormal Involuntary Movement Scale scores of 57% was observed. These data suggest that dihydropyridine calcium channel inhibitors may be effective in the treatment of tardive dyskinesia in schizophrenic patients.

Adult↗
PubMed1990

Effect of ibotenic acid lesions of the medial prefrontal cortex on amphetamine-induced locomotion and regional brain catecholamine concentrations in the rat.

To determine the influence of intrinsic medial prefrontal cortex (MPFC) neurons on regional brain catecholamine turnover, dopamine (DA) and its metabolites were assayed in several brain areas 14 and 28 days after bilateral ibotenic acid (IA) lesions of the MPFC in the rat. The locomotor response to D-amphetamine was also assessed. On the 14th postoperative day levels of DA, homovanillic acid concentrations and 3,4-dihydroxyphenylacetic acid were elevated in the anterior striatum of IA-lesioned animals. Spontaneous and amphetamine-induced locomotion were also increased. These changes disappeared by the 28th postoperative day. It is concluded that destruction of the efferents of the MPFC induces transient increases in DA turnover within the medial striatum and transiently increases spontaneous and amphetamine-induced locomotion.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Effect of nifedipine and anticonvulsants on kainic acid-induced seizures in mice.

The calcium-channel inhibitor nifedipine and several anticonvulsant drugs were evaluated for effects on seizures induced by intracerebroventricular injection of 0.14 microgram of kainic acid. These seizures were markedly exacerbated by valproic acid and moderately inhibited by diazepam. Nifedipine decreased the duration of each individual seizure episode, but did not block the development of seizures. It is concluded that nifedipine prevents the maintenance or propagation of kainate-induced seizures.

Animals↗
PubMed1990

Effects of intraventricular substantia nigra allografts as a function of donor age.

Transplantation of fetal substantia nigra into the brain can alleviate some of the manifestations of animal models of Parkinson's disease. The purpose of the present experiment was to determine the optimal embryonic donor age for solid tissue substantia nigra grafts. Rats with unilateral substantia nigra lesions were tested for rotational behavior in response to apomorphine. Animals then received intraventricular grafts of ventral mesencephalon from fetal donors of 11, 13, 15, 17, or 19 days gestational age, and were tested for rotational behavior 6 and 12 weeks after transplantation. After 12 weeks, animals receiving grafts from donors of 11 through 17 days gestation showed similar decreases (means = 42-58%) in rotation. All 4 groups showed greater decreases in rotation than the 19 day group (17%). In both the 11 and 13 day groups, however, there were substantial decreases in rotational behavior from the 6th to the 12th week testing periods. This study confirms that during a critical period of rat fetal development, between 17 and 19 days gestational age, the substantia nigra loses much of its ability to produce functional effects after transplantation. Grafts from very immature donors did not, however, produce markedly greater effects, and the youngest grafts required more time for the development of maximal effects.

Animals↗
PubMed1990

Characterization of Na(+)-Ca2+ exchange activity in plasma membrane vesicles from postmortem human brain.

Procedures were developed for measurement of Na+/Ca2+ exchange in resealed plasma membrane vesicles from postmortem human brain. The vesicle preparation method permits use of stored frozen tissue with minimal processing required prior to freezing. Vesicles prepared in this manner transport Ca2+ in the presence of a Na+ gradient. The kinetic characteristics of the Na+/Ca2+ exchange process were determined in membrane vesicles isolated from hippocampus and cortex. The Kact for Ca2+ was estimated to be 32 microM for hippocampal and 17 microM for cortical tissue. The maximal rate of Ca2+ uptake (Vmax) was 3.5 nmol/mg protein/15 sec and 3.3 nmol/mg protein/15 sec for hippocampal and cortical tissue, respectively. Exchange activity was dependent on the Na+ gradient, and was optimal in the high pH range. Therefore, membranes in which Na(+)-dependent Ca2+ transport activity is preserved can be isolated from postmortem human brain and could be used to determine the influence of pathological conditions on this transport system.

Brain↗
PubMed1990

Glutamate receptor changes in brain synaptic membranes from human alcoholics.

Brains from human alcoholics and non-alcoholics were obtained shortly after death. The hippocampus was dissected, homogenized, and processed for the isolation of a synaptic membrane-enriched fraction and the study of L-[3H]glutamic acid and 3-((+-)-2-carboxypiperazin-4-yl)-[1,2(3H)propyl-1-phosphonic acid ([3H]CPP) binding sites. The pharmacological characteristics of L-[3H]glutamic acid binding to synaptic membranes isolated from hippocampus corresponded to the labeling of a mixture of N-methyl-D-aspartate (NMDA), kainate and quisqualic acid receptor sites. Synaptic membranes prepared from the hippocampus of individuals classified as alcoholics had significantly higher density of glutamate binding sites than identically prepared membranes from non-alcoholic individuals. In addition, there was a clear definition of a population of L-glutamate binding sites (approx. 10% of total) in the membranes from alcoholics that had a higher affinity for the ligand than the major set of sites labeled in membranes from both alcoholics and non-alcoholics. Neither the age of the individuals at the time of death nor the time that elapsed between death and processing of brain tissue were significant factors in determining either recovery of purified synaptic membranes from brain homogenates or L-[3H]glutamate binding to synaptic membranes. In order to determine whether some of the changes in L-[3H]glutamic acid binding were due to alterations in binding at the NMDA receptor subtype, we also measured binding of [3H]CPP to extensively washed crude synaptosomal membranes. Membranes from brains of alcoholics had higher affinity (3-fold) for [3H]CPP but lower binding capacity (3-fold) when compared with those of non-alcoholics.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗
PubMed1990

A possible role of AA2 excitatory amino acid receptors in the expression of stimulant drug effects.

GDEE, an antagonist of the AA2 or quisqualic acid category of excitatory amino acid receptor, decreases behavioral activity and locomotor stimulation induced by cocaine and amphetamine when locally injected into the nucleus accumbens. The present experiment was intended to examine the effects of systemic GDEE and other excitatory amino acid antagonists on stimulant-induced locomotor activity. GDEE markedly attenuated the stimulant effect of amphetamine, and partially blocked the effects of phencyclidine (PCP). Apomorphine-induced cage climbing behavior was partially decreased by lower dosages of GDEE, but was almost completely blocked by the highest dosage tested. Amphetamine-induced stimulation of locomotor activity was not decreased by any of the other excitatory amino acid antagonists that were tested, including MK-801, 2-amino-7-phosphonoheptanoic acid (APH), or CNQX. APH decreased stereotypy only at a high dosage (250 mg/kg), which also produces ataxia. Several other compounds, including L-glutamic acid gamma ethyl ester (GMEE), L-glutamic acid, glycine, and L-glutamine did not block amphetamine-induced stimulation in molar dosages equivalent to the highest dosage of GDEE (8 mmol/kg). It is concluded that the AA2 excitatory amino acid receptor is important in the expression of activating effects of stimulant drugs.

2-Amino-5-phosphonovalerate↗
PubMed1990

Intracerebral adrenal medulla grafts: a review.

This review summarizes basic and clinical research on intracerebral adrenal medulla grafts, emphasizing potential applications to Parkinson's disease. Properties of intraventricular and intraparenchymal grafts are described, and cell survival and functional effects are compared. It is clear that adrenal medulla allografts survive poorly in the parenchyma of the corpus striatum and better in the lateral ventricle. Nerve growth factor (NGF) may improve the survival of adrenal medulla grafts. In the absence of added NGF even adrenal medulla grafts in the ventricle survive irregularly, and the factors required for graft survival in the ventricle are not well understood. In the 6-hydroxydopamine-lesioned rat model most evidence suggests, not surprisingly, that adrenal medulla grafts produce functional effects only when they survive. These effects may be related to production of catecholamines by the transplanted cells. In addition, adrenal medulla grafts may produce trophic effects on host brain. These effects are most evident in animals with MPTP-induced damage to dopaminergic systems and may be nonspecific, possibly related in part to the brain injury that is induced by graft implantation. Trophic effects may contribute to the functional effects of adrenal medulla grafts: For intraparenchymal grafts, trophic effects that do not require cell survival may contribute small functional changes, while additional behavioral effects may require substantial chromaffin cell survival. The evidence for direct dopamine-mediated effects as compared to trophic mechanisms of action for these grafts in animal models for Parkinson's disease is presented. Clinical studies of adrenal medulla grafts in human patients are examined and compared in detail. When inspected closely, the various clinical studies are in general agreement on most points, although there are differences in the degree of improvement found, both across different studies and individual patients. It is concluded that some beneficial clinical effects occur, with small to modest changes in most patients and substantial improvement in a minority of patients. There also seem to be larger or more consistent changes in durations of "on" and "off" times in L-dihydroxyphenylalanine-treated patients. There are substantial side effects, and it is not clear that the clinical changes are sufficient to justify performing adrenal medulla transplantation in human patients as a routine procedure.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Medulla↗
PubMed1990

Cell adhesion molecules (CAMs) in adrenal medulla in situ and in vitro: enhancement of chromaffin cell L1/Ng-CAM expression by NGF.

We have studied the expression of the cell adhesion molecules (CAMs) L1/Ng-CAM, N-CAM, J1/tenascin, and myelin-associated glycoprotein and their common carbohydrate L2/HNK-1 epitope in normal rat adrenal gland sections as well as in adrenal medulla cell culture with and without NGF stimulation. In situ L1/Ng-CAM was observed on the surface of some but not all chromaffin cell clusters, including their closely associated extracellular matrix (ECM). N-CAM immunoreactivity was present on all chromaffin cells and ECM. The ECM of whole medullas also expressed J1/tenascin molecules. In long-term cultures, nerve growth factor (NGF) stimulation enhanced L1/Ng-CAM, N-CAM, and Thy 1.1 immunolabeling on chromaffin cells and their processes. Process outgrowth was greater from chromaffin cell clusters containing S-100 positive Schwann cells as compared to dispersed single chromaffin cells. When long bundles of chromaffin cell fibers were present, S-100, L1/Ng-CAM, and N-CAM positive Schwann cells were always found and were grouped in distinct clusters in the intervals between the chromaffin cells. In some areas, however, after NGF stimulation some chromaffin cell process development occurred despite an apparent lack of close contact with Schwann cells. NGF-activated chromaffin cells also demonstrated neurofilament- and vimentin-like-immunoreactive filaments within cell bodies and their processes. Chromaffin cells were usually found on a layer of N-CAM and fibronectin positive fibroblasts, and often were associated with laminin-immunoreactive material. These data suggest a possible role of N-CAM and L1/Ng-CAM as well as ECM laminin in process outgrowth from chromaffin cells.

Adrenal Medulla↗
PubMed1990

Cell adhesion molecules in adrenal medulla grafts: enhancement of chromaffin cell L1/Ng-CAM expression and reorganization of extracellular matrix following transplantation.

Intracerebral adrenal medulla grafts have been used in human patients as an experimental treatment for Parkinson's disease, based on studies in animal models of this disorder. However, alterations in chromaffin cell properties after transplantation and the factors controlling graft survival are poorly understood. Since cell adhesion molecules (CAMs) are involved in regeneration and development of neural tissue in vivo and in vitro, the present study was undertaken to determine the expression of CAMs in adrenal medulla isografts. Fragments of rat adrenal medulla were implanted into the right lateral ventricle. The majority of grafts survived quite well, for up to 2 months (the longest studied period). The implanted chromaffin cells did not develop extensive processes. The cells retained tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) immunoreactivity, while phenylethanolamine N-methyltransferase (PNMT) expression was decreased. Surviving transplanted chromaffin cells showed enhancement and spreading of surface L1/Ng-CAM expression as compared to normal chromaffin cells in adrenal medulla. The implanted chromaffin cells demonstrated only partial conversion to neuronal phenotypes. These chromaffin cells did not develop extensive processes, but showed an enhancement of L1/Ng-CAM expression. Surviving chromaffin cells were accompanied by reorganization of their closely associated extracellular matrix (ECM). As compared to normal in situ adrenal medulla, graft ECM demonstrated a substantial increase of L1/Ng-CAM and laminin immunoreactivities and a distinct decrease in J1/tenascin expression. Some adrenal medulla grafts degenerated, particularly when misplaced within the host brain parenchyma. In these cases the grafts showed fragmentation of ECM and gradual disappearance of CAMs. These results suggest that surviving adrenal medulla grafts exhibit increased synthesis of certain CAMs by chromaffin cells, which may be involved in interactions between chromaffin cells and the surrounding ECM. It is speculated that both surviving and degenerating adrenal medulla grafts could provide CAMs and ECM components including laminin to host brain and this way contribute to functional effects of grafts.

Adrenal Medulla↗
PubMed1990

A slight anticonvulsant effect of CNQX and DNQX as measured by homocysteine- and quisqualate-induced seizures.

CNQX and DNQX are compounds that have recently been reported to show potent non-NMDA excitatory amino acid receptor antagonist activity. Effects of these compounds on seizures induced by homocysteine thiolactone and quisqualic acid were studied in order to examine the pharmacological properties of these compounds. In a dosage of 1.16 micrograms intracerebroventricularly (ICV), CNQX prolonged the latency to the onset of quisqualate-, but not homocysteine-induced seizures. DNQX was not effective when given either ICV or systemically, although a 3.78 micrograms dose of DNQX given ICV markedly increased the variability in latency to seizure onset, suggesting a combination of pro- and anticonvulsant effects. Higher dosages of both CNQX and DNQX induced seizure-like activity after ICV injection. These data confirm that CNQX has pharmacological effects corresponding to its effects on cellular responses to quisqualate and kainate agonists, but these effects are weak and may limit its usefulness as a pharmacological tool.

6-Cyano-7-nitroquinoxaline-2,3-dione↗