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E J Singer

Publications and source records attributed to E J Singer.

31 records · Page 2Linked to original sources
PubMed1994

Laboratory evaluations in HIV-1-associated cognitive/motor complex.

Laboratory tests can provide useful information about the presence and effects of HIV-1 in the CNS, but have thus far not yielded definitive diagnostic or prognostic markers of HIV-1-related cognitive and motor complex. The most clinically useful laboratory procedures are MR imaging and CSF examinations. The routine clinical use of MR imaging and CSF examinations, however, is still restricted to providing information for detecting and excluding secondary effects of HIV-1 infection. MR imaging and CT do not appear to be sensitive enough at current resolutions to provide early detection of HIV-1 CNS effects nor to follow disease progression. Several CSF variables are extremely promising as early markers of primary HIV-1 infection of the brain, and may provide preclinical indications for onset of treatment and for evaluation of treatment efficacy. These include CSF quinolinic acid levels, acid dissociated p24 antigen levels, neopterin or beta 2m, intrathecal IgG synthesis rate, and possibly quantitated PCR levels of HIV-1 viral load. Procedures such as nuclear magnetic resonance spectroscopy, SPECT, PET, computerized EEG, EP, and ERPs are all promising candidates for early detection or localization of HIV-1-related brain dysfunction, but at this time all must still be considered primarily research tools. Before any of these procedures can provide reliable diagnostic and prognostic information about primary HIV-1 neurologic disease, currently on-going longitudinal evaluations of large numbers of asymptomatic HIV-1-infected individuals as they progress to neurologically symptomatic disease must be completed. There is currently no laboratory marker in blood or CSF that definitively predicts the risk for HIV-1-associated cognitive/motor complex. HIV-1-associated cognitive/motor complex remains a clinical diagnosis, which is made on the basis of positive neurologic signs and symptoms and abnormal neuropsychological findings after other causes of neurologic disease are excluded. Laboratory measures, such as the electrophysiologic methods and some CSF variables, are likely to remain adjuncts to the diagnosis because, with few exceptions, they provide data that are nonspecific as to etiopathogenesis. Dynamic imaging, electrophysiologic methods, and CSF indices provide presumptive evidence for the presence of HIV-1-associated CNS damage, and with clinical and neuropsychological evidence, could be used to establish a new definition of primary HIV-1-associated CNS disease along the lines used in establishing a diagnosis of multiple sclerosis.(ABSTRACT TRUNCATED AT 400 WORDS)

AIDS Dementia Complex↗
PubMed1993

Zidovudine treatment of the AIDS dementia complex: results of a placebo-controlled trial. AIDS Clinical Trials Group.

The efficacy of two doses of zidovudine was examined for the treatment of the acquired immunodeficiency syndrome (AIDS) dementia complex in a randomized, double-blinded, placebo-controlled trial conducted at nine study centers. For the initial 16 weeks, 40 subjects with mild to moderate AIDS dementia complex were randomized to one of three treatment arms: 400 mg of zidovudine five times daily, 200 mg of zidovudine five times daily, or placebo five times daily. After week 16, patients initially randomized to the placebo group were rerandomized to one of the two zidovudine treatment arms. The primary efficacy end point was improvement in performance on a battery of seven neuropsychological tests; the secondary end point was improvement on a protocol neurological evaluation directed at the cardinal features of the AIDS dementia complex. For the initial 16-week period, average z scores based on the neuropsychological test battery revealed a significant improvement in the combined treatment groups compared to the placebo group; however, when the two treatment groups were compared separately to the placebo group, only the group receiving the higher zidovudine dose exhibited significant improvement. After rerandomization of the placebo patients to one of the two treatment arms at week 16, this group also showed significant improvement in the average neuropsychological z score by week 32. These results extend previous observations that indicate a therapeutic benefit of zidovudine for the treatment of AIDS dementia complex.

AIDS Dementia Complex↗
PubMed1993

AIDS dementia complex complicated by cytomegalovirus encephalopathy.

We have studied longitudinally ten patients with AIDS encephalopathy with respect to pathogenetic roles of human immunodeficiency virus (HIV) and cytomegalovirus (CMV). Three patients manifested typical AIDS dementia complex (ADC) (initially without retinitis and with slowly progressive cognitive, motor and behavioral abnormalities which were zidovudine-responsive, and relatively preserved CD4+ T cells), and seven patients presented with AIDS dementia complex complicated by CMV encephalopathy (ACE) (with CMV retinitis, peripheral neuropathy, altered sensorium, and rapidly declining clinical and immunological status). Whereas only HIV antibody was elevated in the spinal fluid of patients with ADC, both virus infections were active in the central nervous system of patients with ACE as shown by HIV p24 antigenemia and antigenrrhachia, elevated HIV and CMV antibody in the spinal fluid, disseminated CMV infection with retinitis, and basilar ventriculoencephalitis with multinucleated cytomegalic cells containing CMV and HIV proteins and CMV DNA. The recognition of ADC and ACE is important, since some patients with ACE may respond to ganciclovir or foscarnet.

AIDS Dementia Complex↗
PubMed1991

Neopterin and beta 2-microglobulin and the assessment of intra-blood-brain-barrier synthesis of HIV-specific and total IgG.

In HIV-seropositive patients, we evaluated the clinical utility of measuring combinations of serum and CSF levels of neopterin and beta 2-microglobulin (beta 2-M) (by RIA), as well as the intra-blood-brain-barrier (IBBB) IgG synthesis rate, IgG index, and HIV antibody index (by rate nephelometry, EIA, and formulae) for the assessment of HIV infection of the CNS. We studied paired sera and CSF from 31 HIV-seropositive patients: asymptomatic (16), ARC (12), and AIDS (3). A normal serum neopterin level predicts normal levels of serum beta 2-M, CSF neopterin, or CSF beta 2-M in 90%, 100%, and 100%, respectively, of our patients. An elevated serum neopterin level predicts an elevated level of serum beta 2-M or CSF neopterin in 81% and 62%, respectively, of cases. The HIV antibody index and IBBB IgG synthesis rate or IgG index must be determined separately because they do not predict each other and are not predicted by levels of neopterin or beta 2-M.

Antibodies, Viral↗
PubMed1989

Reproductive toxicity of 2-methoxyethanol applied dermally to occluded and nonoccluded sites in male rats.

12-Methoxyethanol (2-ME), also known as Methyl Cellosolve, was applied on the backs of Sprague-Dawley male rats at dose levels of 0, 625, 1250, or 2500 mg/kg/day on occluded (covered) sites, and 0, 1250, 2500, or 5000 mg/kg/day on nonoccluded (uncovered) sites for 7 consecutive days. Because deaths occurred at a dose level of 2500 mg/kg/day among rats with occluded test sites, dosing of this group was discontinued after 5 days. The number and morphology of caudal epididymal sperm, number of testicular spermatids, and weights of reproductive organs were determined on Weeks 4, 7, 10, and 15; fertility was assessed on Weeks--1, 4, 7, 10, and 14. The effects of treatment were dose-related and included a decline in epididymal sperm count and testicular spermatid count, a reduction in weights of testes and epididymides, an increase in the number of sperm with abnormal morphology, and a reduction in fertility in rats exposed to 2-ME. The above effects were seen with or without occlusion, but they were more severe and recovery proceeded at a slower rate when the skin sites were covered.

Administration, Cutaneous↗
PubMed1989

Developmental toxicity of Clarified Slurry Oil applied dermally to rats.

Clarified Slurry Oil (CSO), the heavy residual fraction from the fluidized catalytic cracker, was applied to the shaven backs of groups of 10 pregnant rats at doses of 0, 4, 8, 30, 125, and 250 mg/kg/day. All groups received the test material on gestation days 0-19. CSO was applied undiluted and left uncovered on the skin; collars were placed on the rats to minimize ingestion of the test material. Signs of maternal toxicity, some of which were seen at dose levels as low as 8 mg/kg/day, included vaginal bleeding, decreased body weight gain, reduced food consumption, death, increased relative liver weights, atrophy of the thymus, and aberrant serum chemistry. The number of fetal resorptions/deaths was markedly increased and the number of viable offspring decreased by CSO at dosages of 30 mg/kg/day and above. The group receiving 250 mg/kg/day carried no viable offspring. Fetuses from pregnant females exposed to CSO at dose levels in excess of 8 mg/kg/day were smaller than those from control and 4 mg/kg/day groups, and their skeletons showed decreased ossification. Abnormal external development and visceral development were observed in living and dead fetuses exposed in utero to CSO at dose levels as low as 8 mg/kg/day. Based on these data, 4 mg/kg/day represents the No-Observed-Adverse-Effect-Level for both maternal and developmental toxicity.

Abnormalities, Drug-Induced↗
PubMed1986

A composite model for multiple assays of skin irritation.

A model for skin irritation was developed for simultaneous evaluation of the influence on irritation of abrasion, occlusion, and duration of treatment and for fulfillment of requirements for labeling considerations under DOT, CPSC-FHSA, OSHA, and EEC. This model greatly reduces the number of animals required to address submissions under multiple agencies compared to performing each test separately. In this model, which we have called a Composite Skin Irritation test, a test material is placed on three pairs of intact and abraded sites on each rabbit; one pair of sites is occluded for 4 hours, one for 24 hours, and the other left unoccluded for 24 hours. Results are presented from 88 composite tests with 80 petroleum-related materials. For the materials tested, abrasion of the skin had no effect on the irritation response. Occlusion of the test site generally did not result in dramatic increases in response, except for petroleum refinery streams with a boiling range below 500 degrees F. Exposure for 4 hours rather than 24 hours generally resulted in less irritation; however, for individual compounds, the irritation from the 4-hour exposure could not be predicted from the response to the 24-hour exposure. Of the 80 materials tested, 12 would be labeled as skin irritants under CPSC guidelines, three under OSHA, and 20 under EEC. Of the 20 that would be labeled under EEC criteria, only seven would be labeled under CPSC criteria. At least for petroleum-related materials, results from skin irritation studies performed under one set of conditions cannot be used to predict the degree of irritation that would be produced under a different set of exposure conditions.

Animals↗
PubMed1986

Systemic toxicity from subchronic dermal exposure, chemical characterization, and dermal penetration of catalytically cracked clarified slurry oil.

Clarified slurry oil (CSO), the heavy residual fraction from the fluidized catalytic cracker, was applied to the shaven backs of groups of 10 male and 10 female Sprague-Dawley rats 5 days/week for 13 weeks at doses of 8, 30, 125, or 500 mg/kg/day, and to another group for 2 weeks at doses of 2000 mg/kg/day. The rats were fitted with cardboard Elizabethan collars to minimize the ingestion of the test material, which was applied undiluted and remained uncovered on the skin. A similar group of rats served as controls; they were treated in the same manner except that no CSO was applied to their skin. There was a dose-related mortality and depression of body weight gain in the rats treated with CSO at doses of 30 mg/kg/day or greater; none of the rats dosed at 2000 mg/kg/day survived more than 2 weeks. The primary target organs of CSO toxicity were the liver, thymus, and bone marrow. The effects on the liver included increased weight (250% at 500 mg/kg/day), cholangiolitis, diffuse liver cell degeneration and hypertrophy, necrosis, fibrosis, decreased serum glucose, increased levels of alkaline phosphatase, aspartate aminotransferase, alanine amino transferase, bilirubin, and triglycerides. The thymus was found to be small and upon microscopic examination to be atrophic or hypoplastic. Erythroid hypoplasia was found in the bone marrow of some of the rats dosed at 30 mg/kg/day and increased in severity with increasing dose. The erythroid hypoplasia was accompanied by a dose-related anemia. Even in the rats dosed at 8 mg/kg/day, very slight abnormalities in the bile ducts were observed upon microscopic examination of the liver. Chromatographic separation and analyses demonstrated that CSO contains about 58% 3- to 5-ring polycyclic aromatic hydrocarbons (PAHs) and approximately 8-10% carbazole derivatives. In vitro and in vivo skin penetration studies demonstrated that the carbazole materials penetrate through the skin to a considerable extent (about 44%); less penetration was observed with 2- or 3-ring (8-13%) or 5-ring PAHs (3%).

Administration, Cutaneous↗
PubMed1978

Soft tissue responses to high frequency use of experimental and commercial mouthwashes.

A recent study reported that regular use of commercial mouthwashes produced a significant incidence of oral reactions, including epithelial peeling, inflammation, ulceration and geographic tongue-like lesions. In view of the widespread use of these preparations, without apparent deleterious effects, an investigation of two commercial preparations (Scope, Listerine) and an experimental mouthwash containing cetyl pyridinium chloride was undertaken to assess the possible irritant effects on the oral soft tissue under stringent test conditions. A double blind design was used and soft tissue effects were measured over a two week period. Rinses were used full strength, 20 cc 3 times daily. Examinations were conducted by an oral pathologist at the start and conclusion of the test period, and a record was made of the occurrence of erythema, hyperemia/prominent vasculature, inflammation, petechia, keratosis, tongue coating, and ulceration. These observations did not reveal any soft tissue conditions beyond those which would be expected in the normal population.

Adolescent↗
PubMedDate not supplied

JC virus type 2B is found more frequently in brain tissue of progressive multifocal leukoencephalopathy patients than in urine from controls.

OBJECTIVES: Previous studies have shown that strains of human polyomavirus JC (JCV) of Asian origin (type 2) are much more highly represented in progressive multifocal leukoencephalopathy (PML) brain than would be expected from their frequency of excretion in urine samples of a comparable control group. The present studies were designed to test whether one subtype of type 2 was preferentially elevated. STUDY DESIGN/METHODS: The statistical relation between JCV subtypes represented in PML brain tissue from 51 probands and those in urine samples from 115 control individuals was examined. RESULTS: The proportion of the JCV subtype 2B in PML brain (36%) was highly significantly increased relative to its occurrence in control urine samples (5.9%; P < .001). Type 1 and its subtypes were not different in the PML brain and control urine cohorts. The number of type 4 strains in PML brains was reduced, although the difference did not reach statistical significance (P = .08). CONCLUSIONS: The results predict that the human immunodeficiency virus (HIV)-positive individuals at highest risk of PML infection are those carrying the JCV genotype known as type 2B. Prospective studies will be required to confirm this finding.

Adult↗