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Biomedical subjects

J Ray

Publications and source records attributed to J Ray.

At least 91 records · Page 5Linked to original sources
PubMed1995

Survival and differentiation of adult neuronal progenitor cells transplanted to the adult brain.

The dentate gyrus of the hippocampus is one of the few areas of the adult brain that undergoes neurogenesis. In the present study, cells capable of proliferation and neurogenesis were isolated and cultured from the adult rat hippocampus. In defined medium containing basic fibroblast growth factor (FGF-2), cells can survive, proliferate, and express neuronal and glial markers. Cells have been maintained in culture for 1 year through multiple passages. These cultured adult cells were labeled in vitro with bromodeoxyuridine and adenovirus expressing beta-galactosidase and were transplanted to the adult rat hippocampus. Surviving cells were evident through 3 months postimplantation with no evidence of tumor formation. Within 2 months postgrafting, labeled cells were found in the dentate gyrus, where they differentiated into neurons only in the intact region of the granule cell layer. Our results indicate that FGF-2 responsive progenitors can be isolated from the adult hippocampus and that these cells retain the capacity to generate mature neurons when grafted into the adult rat brain.

Animals↗
PubMed1995

FGF-2-responsive neuronal progenitors reside in proliferative and quiescent regions of the adult rodent brain.

Neurogenesis is restricted to discrete germinal zones within the developing and the adult central nervous systems. With few exceptions, cells that migrate away from these zones and into the parenchyma no longer participate in the generation of new neurons. In this work, we have found that basic fibroblast growth factor is able to stimulate the proliferation of neuronal and glial progenitors isolated from the septum and striatum of adult rats. These progenitors are indistinguishable from those isolated from the adult hippocampus and subventricular zone, two regions that generate neurons well into adult life. Although a variety of cell types are initially isolated from each brain region, the progenitor-like cells from all four regions are capable of considerable proliferation and, with limited serial passage, can be cultured as enriched populations of immature cells that are capable of differentiating into mature glia and neurons following density arrest and growth factor withdrawal. The fact that cells isolated from the septum and striatum proliferate and have the ability to differentiate into neurons once they are removed from their local environment indicates that neurogenesis may be restricted to discrete areas of the developing and the adult brain by regional differences in regulatory signals rather than from an absence of progenitors capable of responding to neurogenic cues.

Animals↗
PubMed1995

Basic fibroblast growth factor increases dopaminergic graft survival and function in a rat model of Parkinson's disease.

The clinical use of fetal neural grafts as an intracerebral source of dopamine for patients with Parkinson's disease has met with limited success. Since basic fibroblast growth factor (bFGF) enhances the survival and growth of dopaminergic neurons in vitro, we explored whether cells genetically modified to produce bFGF would improve the functional efficacy of dopaminergic neurons implanted into rats with experimental Parkinson's disease. Results show that bFGF-producing cells grafted together with fetal dopamine neurons have potent growth-promoting effects on the implanted neurons in vivo. Moreover, rats implanted with such co-grafts display the most pronounced behavioural improvements post-grafting. These findings not only provide insight into the function of bFGF in situ, but also suggest an approach for enhancing the survival and function of dopamine neurons grafted into the damaged brain.

Animals↗
PubMed1995

Expression of biologically active basic fibroblast growth factor by genetically modified rat primary skin fibroblasts.

Basic fibroblast growth factor (FGF-2) is normally expressed as a cell-associated protein, and accordingly it is not clear how it exerts its action on target cells in vivo. It has been proposed that cells release, by death or other mechanisms, small amounts of FGF-2 that then acts in an autocrine manner. To address the question of whether it is necessary that FGF-2 remain cell associated or needs to be secreted from cells to have biological activity, we expressed the 18-kDa form of FGF-2 in primary fibroblasts as a cell-associated (FGF-2-B) or as a secreted (FGF-2-S) protein. FGF-2 protein is detected in cell lysates and membrane fractions of both cell types, whereas it is present in significant amounts only in the conditioned medium of FGF-2-S cells. No FGF-2 is detected in control (untransfected) cells. FGF-2-S cells also grow faster than the control of FGF-2-B cells. Yet, when evaluated for their ability to promote the survival of embryonic hippocampal neurons in vitro, both the cell types are active, establishing the activity of the transgene product. We conclude that FGF-2 is active when engineered to be expressed as a cell-associated form or secreted from cells.

Animals↗
PubMed1995

Pharmacokinetics and bioavailability of fluconazole in two groups of males with human immunodeficiency virus (HIV) infection compared with those in a group of males without HIV infection.

Fluconazole pharmacokinetics, including absolute bioavailability, were determined for one group of controls (n = 10) and two groups of people with human immunodeficiency virus (HIV) infection (those with CD4+ T-cell counts of less than [n = 4] or greater than [n = 9] 200 cells per mm3). Twenty subjects received four doses of fluconazole; three doses were oral (50, 100, and 400 mg), and one dose was intravenous (either 50, 100, or 400 mg). The other three subjects received one or two doses. The groups were comparable in terms of the weight, body mass index, and estimated creatinine clearance of the subjects, but the people with HIV infection were older. Pharmacokinetic parameters indicated linearity in all subjects; the area under the plasma concentration-time curve and the maximum concentration increased in proportion to the dose. The fraction of an oral dose of fluconazole absorbed approximated unity in all three groups of subjects. The mean (+/- standard deviation) plasma clearance of fluconazole was lowest in the group of subjects with low CD4+ T-cell counts; the value for this group was 0.74 +/- 0.19 liter/h, compared with 0.97 +/- 0.19 liter/h in the group with HIV infection and CD4+ T-cell counts of greater than 200 cells/mm3 and 1.18 +/- 0.23 liter/h in the group of control subjects (P < 0.05). The volume of distribution was lower in those with HIV infection (P = 0.04, corrected for weight). The half-life was longest in people with HIV infection and low CD4+ T-cell counts (P = 0.01). This study has shown that some differences do exist between the pharmacokinetics of fluconazole in people with HIV infection and those in noninfected controls.

Administration, Oral↗
PubMed1995

Isolation, characterization, and use of stem cells from the CNS.

The nervous system of adult mammals, unlike the rest of the organs in the body, has been considered unique in its apparent inability to replace neurons following injury. However, in certain regions of the brain, neurogenesis occurs postnatally and continues through adulthood. The nature, fate, and longevity of cells undergoing proliferation within the CNS are unknown. These cells are increasingly becoming the focus of intense scrutiny; this is a recent development that has led to considerable controversy over the appropriate terminology to describe neural cells as they pass through different stages of proliferation, migration, and differentiation. Continuing studies detailing the properties of mitotic populations in the adult CNS will provide a better understanding of the nature of these cells during their development and should lead to a more consistent nomenclature. Studies of neural precursors isolated from the embryonic brain have indicated that many subgroups of cells undergo mitosis and subsequent differentiation into neurons and glia in vitro. A number of substances, such as growth factors and substrate molecules, are essential for these processes and also for lineage restriction and fate determination of these cells. Recent studies have shown that cells with proliferative capabilities can also be isolated from the adult brain. The nature of these cells is unknown, but there is evidence that both multipotent cells (stem cells) and lineage-restricted cells (neuroblasts or glioblasts) are resident within the mature CNS and that they can be maintained and induced to divide and differentiate in response to many of the same factors that influence their embryonic counterparts. Presently, it is unclear how many potentially quiescent precursor cells exist in the adult brain or what combination of growth factors and substrate molecules is involved in the proliferation and differentiation of these cells. Some of these questions are currently being addressed by using immortalized neural precursors or growth factor-expanded populations of primary precursors to model precursor responsiveness to environmental manipulations. Because in vitro culture conditions are unlikely to provide all of the factors necessary for inducing the proliferation and differentiation of neural precursors, recent studies have explored the properties of well-characterized precursor populations after implantation back into specific regions of the developing or adult CNS. These studies have highlighted the importance of the microenvironment in precursor differentiation and further suggested that precursor plasticity is a characteristic that is probably common to neural precursors throughout the CNS.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1995

Integrity of the first metatarsophalangeal joint: a biomechanical analysis.

Five fresh-frozen cadaver feet obtained from traumatic amputations were tested during hyperdorsiflexion stress of the first metatarsophalangeal joint. Three different types of injury were observed: (1) rupture of the capsule proximal to the sesamoids, (2) rupture of the plantar plate distal to the sesamoids, and (3) rupture of the capsular structures medially, allowing a lateral swing of the sesamoids around the metatarsal head. Incomplete dislocation can be associated with significant damage to the plantar plate and other soft tissues of the foot.

Adult↗
PubMed1995

The marriage of risk management and the processes of patient care.

So, your organization is considering taking on a capitation contract. Or you have already done so. Sooner or later, most physician executives with whom I have worked have asked the question: "How the hell are we going to manage this thing so we don't go broke?" Good question. Here, in brief, is the answer: Accepting capitated contracts without having the resources to manage both insurance-like risk and the process of caring for capitated patients is roughly equivalent to flying through mountains shrouded by clouds: Sooner or later, a mountainside is likely to appear in your windshield, close up and closing rapidly, at a point where it is too late to do anything about it!

Capitation Fee↗
PubMed1995

Parenteral ciprofloxacin in persistent diarrhoea in children.

In a controlled trial of 30 cases of persistent diarrhoea in infants, ciprofloxacin was used parenterally for systemic antibiotic therapy. Group A cases (15 in number) were treated with parenteral ciprofloxacin and group B control cases (remaining 15) were treated with parenteral ampicillin and chloramphenicol or ampicillin/amikacin along with treatment of dehydration and malnutrition. All group A cases had excellent response and 9 infants of group B had no response up to day 4. After stopping all other drugs and with parenteral ciprofloxacin they responded favourably. Follow-up of all the cases was done regularly every 2 weeks for 6 months after discharge. No toxicity of ciprofloxacin was noted.

Anti-Bacterial Agents↗
PubMed1994

Storage, metabolism, and processing of 125I-fibroblast growth factor-2 after intracerebral injection.

Basic fibroblast growth factor (FGF-2) is a potent trophic agent for both neuronal and non-neuronal cells of the mammalian CNS. It can enhance survival and neurite outgrowth of a variety of neuronal types in vitro and in vivo, and recently has been shown to stimulate neuroblast proliferation in culture. To determine the most effective means of introducing FGF-2 into the brain, and to further our understanding of the behavior of exogenous FGF-2 following intracerebral injection, we examined the diffusion and degradation of 125I-FGF-2 following intraventricular or intraparenchymal injection. SDS-PAGE and autoradiography show that when radiolabelled FGF-2 is injected into the parenchyma of the rat brain, it remains at the site of injection where it is detectable for several days. During this time, it is slowly metabolized to 2 specific heparin-binding metabolic fragments that are virtually identical to the ones described for its metabolism by neurons and astrocytes in vitro. Microscopic examination and autoradiography of these tissue sections show that within these areas, FGF-2 diffuses throughout the site of injection. Initially, it migrates along adjacent fiber tracts, binds to specific cells and to basement membranes of the microvasculature, but later on it remains associated to basement membranes and non-neuronal cells. Based on its slow clearance and slow rate metabolic degradation, this FGF-2 is presumed to be in a sequestered form and to have limited activity. In contrast, the intraventricular injection of 125I-FGF leads to a rapid clearance, with some binding to ependymal cells lining the ventricles and little translocation into the parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Fibroblasts genetically modified to produce nerve growth factor induce robust neuritic ingrowth after grafting to the spinal cord.

The influences of neurotrophic factors on adult mammalian spinal cords are incompletely understood. In the present experiment, we utilized somatic gene transfer to examine the effects of nerve growth factor (NGF) on the unlesioned spinal cords of adult Fischer rats. Fischer 344 rat primary fibroblasts were genetically modified in vitro to produce and secrete NGF, then grafted to spinal cords at the T7 level. Grafts survived in vivo for periods of up to 1 year, and induced an extremely robust ingrowth of spinal neurites. Control and basic fibroblast growth factor-producing grafts did not promote extensive neurite growth. Neurites penetrating the NGF grafts were of sensory origin, since they labeled immunocytochemically for calcitonin gene-related peptide but not markers of other neuronal transmitter phenotypes. Electron microscopy revealed that neurites within NGF-secreting grafts were enveloped in glial cell processes and that axons frequently became myelinated. These results indicate that (i) genetically modified cell grafts are a useful model for studying trophic factor effects in the adult mammalian spinal cord, (ii) sensory neurites maintain robust NGF responsiveness into adulthood, and (iii) sprouting neurites can follow glial channels and become myelinated in the adult spinal cord. Grafts of fibroblasts genetically modified to secrete trophic factors merit study as potential tools for promoting regeneration after spinal cord injury.

Animals↗
PubMed1994

Somatic gene transfer to the adult primate central nervous system: in vitro and in vivo characterization of cells genetically modified to secrete nerve growth factor.

Somatic gene transfer offers a means of delivering substances to the central nervous system (CNS) in a regionally specific, high-dose, chronic and well-tolerated manner. Studies in rats have shown that genetically modified cell grafts can prevent neuronal degeneration and promote functional recovery after injury and can improve cognitive function in aged subjects. To assess the potential utility of somatic gene transfer techniques in primate models, retroviral vectors were used to modify genetically monkey and human primary skin fibroblasts to produce and secrete human nerve growth factor (NGF). In vitro, all cell types produced NGF and sustained this production through cell growth to confluency, as determined by both Northern blot analysis and ELISA. Adult human fibroblasts produced as much NGF as did young human fibroblasts. Monkey fibroblasts genetically modified to produce NGF were then grafted to intact adult rhesus and cynomolgous monkey brains. Among nine primates that received a total of 76 grafts, surviving cells were found in all subjects up to the maximal experimental timepoint of 6 months. Cholinergic fibres from the host brain penetrated NGF-secreting grafts up to 6 months after grafting, but showed little penetration in control grafts lacking the NGF gene. Autografts survived better than allografts. These findings indicate that both human and primate fibroblasts can be transduced to produce and secrete NGF, can maintain this production whether in a growing or quiescent state and can elicit robust sprouting responses when primate fibroblasts are grafted to the adult brain. Cells genetically modified to produce trophic factors are a useful model for studying in vitro and in vivo CNS plasticity and for testing potential therapies for neurodegenerative conditions.

Animals↗
PubMed1994

Grafting of nerve growth factor-producing fibroblasts reduces behavioral deficits in rats with lesions of the nucleus basalis magnocellularis.

Rats received bilateral lesions of the nucleus basalis magnocellularis by infusion of biotenic acid. Two weeks after the lesion, a suspension of genetically modified primary rat fibroblasts was grafted dorsal to the nucleus basalis magnocellularis (2 x 10(5) cells per side). The fibroblasts were either infected with the gene for human beta-nerve growth factor or Escherichia coli beta-galactosidase. The nerve growth factor-producing fibroblasts released 67 ng nerve growth factor/10(5) cells per day in vitro. Two weeks after implantation of the fibroblasts, spatial learning was tested in the Morris water-maze. Nerve growth factor-producing fibroblasts, but not beta-galactosidase-producing fibroblasts ameliorated the deficit in acquisition of the water-maze task. In addition, spatial acuity was improved to near-normal levels by the nerve growth factor-producing grafts. Choline acetyltransferase activity in cortical areas and hippocampus was not affected by the nerve growth factor-producing grafts. Both grafted groups showed a similar reduction in the level of dopamine, but not homovanillic acid or 3-methoxytyramine, in the frontal cortex. Levels of norepinephrine, epinephrine and serotonin and their metabolites in the neocortex and hippocampus were not affected by the lesion or the grafts. Nerve growth factor-producing grafts increased the size of remaining nerve growth factor-receptor (p75) immunoreactive neurons in the nucleus basalis magnocellularis by 25%. Nucleus basalis magnocellularis lesions reduced the integrated optic density of choline acetyltransferase-positive fiber staining in the ventral neocortex by 46%, but nerve growth factor-producing grafts restored this area to 86% of control. These data suggest that nerve growth factor-producing grafts can cause a marked behavioral improvement, probably through the partial restoration of the lesioned projection from nucleus basalis magnocellularis to neocortex.

Animals↗
PubMed1994

In vivo and ex vivo gene transfer to the brain.

The use of gene transfer techniques to express novel proteins within different cellular populations has provided insights into the function and plasticity of the brain. Recently, this technique has been successfully used to explore physiological processes within the CNS and to intervene in neurodegenerative disease and cancer. Progress in manipulating transgene products in vivo and in achieving cell-specific targeting of genetic material offers promise for enhancing the usefulness of this technique and its therapeutic potential for treating human disorders of the CNS.

Animals↗