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Biomedical subjects

J D Adams

Publications and source records attributed to J D Adams.

At least 55 records · Page 3Linked to original sources
PubMed1993

New aspects of brain oxidative stress induced by tert-butylhydroperoxide.

Many diseases and aging may be associated with oxidative stress in the brain. However, the effects of oxidative stress in the brain should be more clearly described, especially in terms of effects on brain reduced glutathione (GSH). This issue was addressed by intracerebroventricular injection of a direct-acting oxidative stress inducing agent, tert-butylhydroperoxide. Oxidized glutathione (GSSG) levels in the brain increased by as much as 90-fold during tert-butylhydroperoxide-induced oxidative stress. At the same time, brain GSH levels decreased. The brain appears to retain GSSG and not reduce it or export it efficiently. Vitamin E levels in the striatum increased during tert-butylhydroperoxide-induced oxidative stress. Aging alters the ability of the brain to detoxify an oxidative stress, in that 8-month-old mice retain GSSG in their brains much more than 2-month-old mice. Eight-month-old mice were much more susceptible to tert-butylhydroperoxide-induced toxicity than 2-month-old mice. This may indicate that aging makes the brain more susceptible to oxidative damage.

Aging↗
PubMed1993

Paclitaxel for platinum-refractory ovarian cancer: results from the first 1,000 patients registered to National Cancer Institute Treatment Referral Center 9103.

PURPOSE: To provide an investigational drug, paclitaxel, now commercially available, to women with refractory ovarian cancer and to evaluate response and toxicity in these patients. PATIENTS AND METHODS: Patients with platinum-refractory ovarian cancer, Eastern Cooperative Oncology Group (ECOG) performance status 0 to 3, at least three prior chemotherapy regimens, adequate hepatic and renal function, and no significant cardiac history were eligible. Patients were treated with paclitaxel 135 mg/m2 administered by 24-hour continuous intravenous infusion every 3 weeks. RESULTS: Leukopenia was the most frequent toxicity, with 78% of patients experiencing grade 3 or 4 toxicity. Other grade 3 and 4 toxicities were less common: fever (33%), infection (12%), thrombocytopenia (8%), vomiting (7%), cardiac (2%), neurologic (2%), and mucositis (1%). Fifteen treatment-related deaths (1.5%) were reported. The objective response rate was 22% (4% complete response [CR], 18% partial response; 95% confidence interval [CI] for overall response, 19% to 25%). The median time to progression from treatment initiation was 7.1 months in responding patients and 4.5 months for all patients. The median survival duration was 8.8 months. CONCLUSION: Paclitaxel has shown activity in women with platinum-refractory ovarian cancer, and it can be administered with an acceptable safety profile. Further research is needed to determine the optimal role of paclitaxel in the primary and salvage treatment of ovarian cancer.

Adult↗
PubMed1993

Taxol: a history of pharmaceutical development and current pharmaceutical concerns.

Taxol, a unique diterpene anticancer compound derived from the bark of the Taxus brevifolia (Pacific yew) tree, induces cytotoxicity by a novel mechanism of action. An antimicrotubule agent, Taxol promotes the formation and stabilization of the tubulin polymer unlike other anticancer agents that induce microtubule disassembly. Because of its poor aqueous solubility, Taxol is formulated as a solution in 50% Cremophor EL and 50% dehydrated alcohol, USP. The Cremophor EL and dehydrated alcohol vehicle used in the formulation of Taxol creates some interesting challenges for its preparation and administration. The pharmaceutical concerns associated with the preparation and administration of Taxol are discussed.

Animals↗
PubMed1993

Pneumocystis carinii pneumonia in HIV infected patients: effects of the diseases on glutathione and glutathione disulfide.

Human immunodeficiency virus (HIV) infection is associated with altered levels of glutathione (GSH) in cells and extracellular fluids. GSH is essential for lymphocyte proliferation and inhibits HIV replication. Therefore, determination of GSH and glutathione disulfide (GSSG) levels could be useful as indicators of the progression of the disease. Thyroid hormone levels are altered in acquired immuno-deficiency syndrome (AIDS), such that thyroid hormone might be a useful prognostic indicator of the severity of AIDS. Pneumocystis carinii pneumonia (PCP) is a debilitating disease of the lung that can accompany HIV infection. The effects of pulmonary infections were assessed in AIDS patients on thyroid hormone, GSH, GSSG levels and other parameters. Two groups of AIDS patients were selected, a group with PCP and a control group with other respiratory diseases. GSH was evaluated in plasma, pulmonary lavage fluid, pulmonary biopsy tissue and buccal cells. Levels of GSSG in pulmonary lavage fluid were higher in PCP patients than in controls, which suggests that PCP patients suffer from oxygen radical toxicity in their lungs. PCP patients may have altered plasma GSH utilization such that damaged lung tissue may become less efficient at using plasma GSH. Patients with PCP may have altered CD4 cell functions such that thyroid hormone levels do not correlate with CD4 cell counts. Patients with AIDS and secondary infections of the lung were found to have altered GSH redox states, probably indicative of physiologic adaptation to AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1992

Relative potency estimates of acceptable residues and reentry intervals after nerve agent release.

In the event of an unplanned release of a chemical warfare agent during any stage of the Chemical Stockpile Disposal Program, the potential exists for off-post contamination of drinking water, forage crops, grains, garden produce, and livestock. The more persistent agents, such as the organophosphate nerve agent VX, pose the greatest human health concern for reentry. A relative potency approach comparing the toxicity of VX to organophosphate insecticide analogues is developed and used to estimate allowable residues for VX in agricultural products and reentry intervals for public access to contaminated areas. Analysis of mammalian LD50 data by all exposure routes indicates that VX is 10(3) to 10(4) times more toxic than most commercially available organophosphate insecticides. Thus, allowable residues of VX could be considered at concentration levels 10(3) to 10(4) lower than those established for certain insecticides by the U.S. EPA. Evaluation of reentry intervals developed for these organophosphate analogues indicate that, if environmental monitoring cannot reliably demonstrate acceptable levels of VX, restricted access to suspect or contaminated areas may be on the order of weeks to months following agent release. Planning for relocation, mass care centers, and quarantine should take this time period into account.

Chemical Warfare Agents↗
PubMed1992

The acute retinal histopathology of MPTP.

The effects of MPTP on the retina have been examined with emphasis on the effects that are apparent within a few hours of administration. Histopathologic changes were found within one day after MPTP administration. These changes were most prominent in the Muller cells, which demonstrated edematous changes in the cellular processes and occasionally pyknotic nuclei in the inner nuclear layer. Capillary endothelial cells also were damaged by MPTP administration as evidenced by disruption of the cellular cytoplasms. This damage may have caused pooling of blood in the blood vessels of the retina. Finally, mitochondria in some retinal layers may have been altered by MPTP administration with swelling and possible rupture seen in some cells. These acute effects of MPTP may be involved in the formation of lesions to dopaminergic amacrine cells found in the retina following MPTP exposure.

Animals↗
PubMed1991

Alzheimer's and Parkinson's disease. Brain levels of glutathione, glutathione disulfide, and vitamin E.

Human brain levels of glutathione (GSH), glutathione disulfide (GSSG), and vitamin E were measured in neurologically normal control patients and two groups of patients with neurodegeneration: those with Alzheimer's disease (AD), and AD with some features of Parkinson's disease (AD-PD). Control brain samples contained GSH levels more than 50 times higher than GSSG. The levels of GSH were highest in the caudate nucleus and lowest in the medulla. In patients with AD or AD-PD, hippocampal levels of GSH were significantly higher than controls. Patients with AD also demonstrated high GSH levels in the midbrain compared to normal. In contrast, patients with AD-PD did not have significantly elevated GSH levels in this site. GSSG levels were not significantly different in any brain region between controls and diseased patients. In control brains, the medulla had higher levels of vitamin E than any other brain region. The caudate nucleus had the lowest levels, which were about half the levels in the medulla. Control levels of vitamin E in the midbrain were about 18.8 micrograms/g. In AD patients the midbrain levels of vitamin E doubled to 42.3 micrograms/g. This doubling also occurred in AD-PD patients where midbrain vitamin E levels increased to 44.0 micrograms/g. These results may indicate that compensatory increases in GSH and vitamin E levels occur following damage to specific brain regions in patients with AD or AD-PD.

Aged↗
PubMed1991

Effects of MPTP on the cerebrovasculature.

The neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, has been shown to cause pooling of blood in the brain microvasculature and decrease the permeability of the blood-brain barrier. All areas of the brain examined in this study were affected. This study points out the possibility that reduced nutrient uptake, hypoxia and ensuring free radical damage are involved in the mechanism of toxicity of this neurotoxin.

Animals↗
PubMed1991

Oxygen free radicals and Parkinson's disease.

The involvement of oxygen radicals in the pathogenesis of Parkinson's disease has been suggested for some time. This article reviews the evidence supporting the involvement of oxygen radicals in the disease process in the brain. This includes a discussion of iron, lipid peroxidation, peroxidase, catalase, superoxide dismutase, and glutathione levels in the brain. In addition, various theories of induction of Parkinson's disease are discussed in relation to the possible involvement of oxygen radicals. These theories include the environmental toxin theory, the dopamine turnover theory, and the cerebral blood flow theory.

Brain↗
PubMed1990

MPTP toxicity in the mouse brain and vitamin E.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) caused transient alterations in vitamin E levels in every brain region examined. However, vitamin E returned to normal levels within a few hours in all brain regions but the substantia nigra, where at 2 days vitamin E levels first rose above normal levels. Vitamin E deficient mice were much more susceptible to MPTP toxicity than controls, in terms of lethality and DOPAC depletion in the substantia nigra. However, in the same vitamin E deficient mice, the striatum was partially protected from neurotransmitter and metabolite depletion by MPTP. The mechanism of toxicity of MPTP may differ in the striatum and the midbrain.

Animals↗