Longitudinal MRI shows no cerebral abnormality in chronic fatigue syndrome.

MRI has previously provided conflicting results when used to search for brain abnormalities in sufferers of chronic fatigue syndrome (CFS). Eighteen CFS patients and nine healthy volunteers each underwent MRI on two occasions, one year apart. The resulting images were examined for abnormalities in brain atrophy, deep white matter hyperintensities (WMH) and cerebral blood and cerebrospinal fluid (CSF) flow.

The effects of bee (Apis mellifera) venom phospholipase A2 on Trypanosoma brucei brucei and enterobacteria.

The potential role of phospholipases in trypanosomiasis was investigated using bee venom phospholipase A2 (bvPLA2) as a model. The effects of bvPLA2 on the survival of Trypanosoma brucei brucei, 2h and 12h cultures of Enterobacter cloacae, Escherichia coli, Citrobacter freundii were studied. About 1 mg ml(-1) bvPLA2 was trypanocidal after 30 min.

The involvement of calcium in the protective and toxic (nonlinear) responses of rodent and human astroglial cells.

The involvement of [Ca(2+)](i) in the reactive changes of astrocytes which accompany exposure to different chemicals were studied in cultures of C6 and 1321N1 cells. Cells were exposed to up to three serial pulses of the differentiating agent dBcAMP, which induces activation-type changes in the cells. Other cells, with or without the dBcAMP treatments, were treated with a range of concentrations of the antidepressants amitriptyline and fluoxetine and the glial toxicants acrylamide and chloroquine.

The Third FRAME Toxicity Committee: working toward greater implementation of alternatives in toxicity testing.

FRAME (the Fund for the Replacement of Animals in Medical Experiments; http://www. frame.org.

Mast cells, histamine and the pathogenesis of intestinal damage in experimental Trypanosoma brucei brucei infections.

Intestinal damage with increased permeability is a prominent feature of experimental African trypanosomiasis. The possible involvement of mast cells and histamine in the altered gut integrity was investigated, at the level of the jejunum, in BALB/c mice infected with Trypanosoma brucei brucei. Mast cells were studied by selective staining of granule content with Alcian Blue/Safranin and quantitative histology, and histamine concentrations were determined by a fluorimetric method.

Responses of Cultured Astrocytes, C6 Glioma and 1321NI Astrocytoma Cells to Amyloid beta-Peptide Fragments.

The effect of amyloid beta-peptide (betaAP), which can have both neurotrophic or neurotoxic effects on neurons and has been implicated in the pathogenesis of Alzheimer's disease (AD), was studied on astrocytes using primary cultures and astrocyte cell lines (rat C6 glioma, human 1321NI astrocytoma cells). The cultures were exposed to 0.0005-50 mug/ml) betaAP fragments 1-40, 25-35, 31-35, or 40-41 (control) for 24 hr.

Lead toxicity, locomotion and feeding in the freshwater snail, Lymnaea stagnalis (L.).

The effects of lead (5 or 10 ppm) on the survival of the freshwater snail Lymnaea stagnalis (L.) collected from lead contaminated or uncontaminated environments were evaluated under controlled laboratory conditions. The animals from the contaminated environment had significantly greater survivability than those from the unpolluted environment to subsequent acute (up to 24 days) exposure to lead.

The relationships between endotoxins, nitric oxide and inflammatory cytokines in blood and intestinal tissues in experimental Trypanosoma brucei brucei infections.

Increased levels of circulating endotoxins are a feature of both human and experimental African trypanosomiasis. Studies with rats and mice have shown that these may originate from intestinal damage with altered permeability of the gut epithelium. Endotoxins are potent immunomodulatory substances which can initiate the production of a range of cytokines and mediators from different cell types.

The relationships between intestinal damage and circulating endotoxins in experimental Trypanosoma brucei brucei infections.

The involvement of intestinal damage in experimental African trypanosomiasis was investigated in rats infected with Trypanosoma brucei brucei by measuring the urinary excretion of the previously administered non-metabolizable sugar probes, D-mannitol and lactulose, and the flux of FITC-dextran across isolated, everted gut segments. There was increased urinary recovery and flux of the sugar probes across the intestine which were significant (P < 0.05) and maximum at day 21 of the infection, but subsequently reduced, in the terminal stages of infection (day 33 p.

Assessment of DNA damage in C6 glioma cells after antidepressant treatment using an alkaline comet assay.

The effects of acute (24 h) exposure to the antidepressants amitriptyline, imipramine (both tricyclics), fluoxetine (a selective serotonin re-uptake inhibitor) and tranylcypromine (a monoamine oxidase inhibitor) on DNA damage in cultured C6 rat glioma cells were determined using an alkaline comet assay. The effects of manipulation of intracellular cyclic AMP by pretreatment with dibutyryl cyclic AMP (dBcAMP) and 3-isobutyl-1-methylxanthine (IBMX) were also studied. For fluoxetine, the effects of addition of exogenous glutathione (GSH) and pretreatment with L-buthionine sulfoximine (BSO) were also assessed.

Astrocyte phenotype and prevention against oxidative damage in neurotoxicity.

Astrocytes possess a potent array of protective systems. These are chiefly targeted against oxidised products and radicals, which are frequently present in increased amounts following exposure of nervous tissue to a range of toxic insults. Following exposure to the toxic chemicals astrocytes commonly respond by alteration in phenotype with upregulation of a large number of molecules, including those controlling the protective systems.

Antioxidant defense against antidepressants in C6 and 1321N1 cells.

The effects of pretreatment with the antioxidants reduced glutathione (GSH), ascorbate (ASC), Trolox (TROL), and combined ascorbate and Trolox (ASC/TROL) exposure on the acute (24 h) toxicities (EC50 value) of the antidepressants amitriptyline, imipramine (tricyclic antidepressants), fluoxetine (a selective serotonin reuptake inhibitor; SSRI), and tranylcypromine (a monoamine oxidase inhibitor; MAOI) were determined in the rat (C6) glioma and human (1321N1) astrocytoma cell lines using the neutral red uptake assay. The effects of pretreatment with buthionine-[S, R]-sulfoximine (BSO), and manipulation of intracellular cyclic AMP (cAMP) using isoproterenol (beta-receptor agonist), 3-isobutyl-1-methylxanthine (IBMX; a phosphodiesterase inhibitor), and dibutyryl cyclic AMP (dBcAMP; cAMP analogue) on antidepressant toxicity were also determined. Protective responses were observed after antioxidant treatments and manipulation of cAMP in both C6 cells pretreated with dBcAMP (+dBcAMP) and 1321N1 cells not pretreated with dBcAMP (-dBcAMP), with a few exceptions in 1321N1 cells (-dBcAMP).

Evaluation of toxicity indicators in rat primary astrocytes, C6 glioma and human 1321N1 astrocytoma cells: can gliotoxicity be distinguished from cytotoxicity?

A comparison was made of rat primary astrocytes, C6 glioma cells pre-treated with dibutyryl cyclic AMP, and the human astrocyte 132N1 cell line using a range of 40 compounds and the neutral red (NR) assay. The 40 chemicals included substances known to be toxic to astrocytes or neurons, to be generally cytotoxic or not thought to be toxic to nervous tissue. For those compounds which were toxic, changes in glial fibrillary acidic protein (GFAP) levels were measured in the primary and C6 cultures, and changes in vimentin and S-100 measured in the C6 cells.

Glutathione modifies the toxicity of triethyltin and trimethyltin in C6 glioma cells.

It has been demonstrated that exposure to mercury or cadmium compounds causes alterations in the glutathione system in a model glial cell line, C6. Here we report that two organic tin compounds, triethyltin (TET) and trimethyltin (TMT), are also toxic to these cells with EC50 values for cell death of c. 0.

Hypertrophy and increased glial fibrillary acidic protein are coupled to increased protection against cytotoxicity in glioma cell lines.

This study examined the associations of increased glial fibrillary acidic protein (GFAP) levels and hypertrophie changes with susceptibility to toxic insult in C6 rat glioma cells. The cells were treated with serial pulses of dibutyryl-cAMP (dBcAMP) (each 48 hr) which increased levels of GFAP approximately twofold and the surface to volume ratio by approximately 1.7 times after the third pulse.

Endotoxin antibodies in African sleeping sickness.

Antibodies to the core region of endotoxin (endotoxin core antibodies, EndoCAb), which cross-react with endotoxin from a range of Gram-negative bacteria, are maintained in relative homeostasis in health, but undergo marked changes in a number of different diseases associated directly or indirectly with endotoxaemic or septicaemic states. The levels of EndoCAb IgG in the blood and cerebrospinal fluid (CSF) of 35 late-stage sleeping sickness patients and 9 control individuals were measured by ELISA. EndoCAb levels were significantly elevated in the patient blood (mean EndoCAb value 290 MU/ml cf.

Protective roles of glutathione in the toxicity of mercury and cadmium compounds to C6 glioma cells.

The neurotoxic effects of mercury (II) chloride, methylmercury (MeHg) and cadmium chloride on astrocytes were modelled using C6 glioma cell cultures. All three compounds were cytotoxic to these cells with an order of potency of cadmium > MeHg > mercurychloride. Addition of reduced glutathione (GSH) to the media protected the cells in all three cases, whereas depletion of GSH with l-buthionine-S,R-sulfoximine enhanced the toxicity of cadmium and mercury chloride but not MeHg.

Endotoxins in the blood and cerebrospinal fluid of patients with African sleeping sickness.

Endotoxin levels were measured in the blood and cerebrospinal fluid (CSF) of control individuals and 2 groups of patients with African sleeping sickness. Endotoxin levels were markedly elevated in the blood (infected groups mean endotoxin values 40.2 pg/ml and 53.

Use of the MTT assay for estimating toxicity in primary astrocyte and C6 glioma cell cultures.

Primary cultures of rat cortical astrocytes were exposed to 25 neurotoxic and non-neurotoxic compounds for 24 hr over a concentration range of 0.001 to 1000 mug/ml and the effects were quantified using the MTT assay. EC(50) values were obtained for nine of the compounds in the tested range, while increases in MTT conversion were seen at sub-cytotoxic concentrations for 12 compounds.

Royal Society of Tropical Medicine and Hygiene Meeting at Manson House, London, 19 May 1994. Trypanosomiasis and the nervous system. Pathology and immunology.

Damage to the nervous system occurs in both African and American trypanosomiases, but it differs considerably in form and extent in each disease, and with different strains and disease stages. With Trypanosoma brucei infections there is a progressive central nervous system (CNS) pathology which involves the meninges, choroid, blood-brain barrier, and immunopathological changes including perivascular infiltrations, astrocyte activation and alterations in the cytokine/mediator network. These changes underly the altered behaviour in the late or secondary disease stages, prevalent in the chronic gambian form, characterized by hypersomnia leading, if untreated or if treatment is followed by reactive changes, to coma and death.

Blood-brain barrier damage in experimental African trypanosomiasis.

African sleeping sickness is characterized by progressive central nervous system (CNS) involvement, leading to the so-called secondary or late stage in which there are widespread inflammatory changes with lymphoplasmocytic infiltration. A study was made of blood-brain barrier (BBB) integrity in the late stages of a rodent model by assessing the uptake of the fluorescent fluid-phase marker sulphorhodamine B into the brain tissue. Brain oedema was estimated from brain weight, density and electrolyte concentrations.