Biomedical subjects

J D Glass

Publications and source records attributed to J D Glass.

At least 55 records · Page 3Linked to original sources

PubMed1997

Role of neural cell adhesion molecule and polysialic acid in mouse circadian clock function.

The suprachiasmatic nuclei (SCN) express the highly polysialylated form of the neural cell adhesion molecule (NCAM) that has been proposed to promote plasticity in the adult brain. To investigate a role for NCAM in SCN circadian clock function, we examined the daily locomotor rhythm of mice homozygous for a mutation, Ncamtm1Cwr, which results in deletion of the NCAM-180 isoform that in brain carries polysialic acid (PSA). Mutant mice entrained well to a 12 hr light/dark cycle but exhibited a significantly shortened free-running period and longer activity duration under constant darkness (DD) than did wild-type mice. By the third week of DD treatment, circadian rhythmicity in the mutant was abolished. Immunocytochemical analyses of the mutant SCN revealed an abnormal number and distribution of vasoactive intestinal polypeptide-producing neurons, suggesting a developmental effect of the mutant phenotype; however, a direct physiological effect of the mutation on clock function was indicated by the fact that removal of PSA from adult wild-type SCN by microinjection of endoneuraminidase shortened the free-running period to a similar extent as in the mutant. Together, these data indicate critical roles for NCAM and PSA in the development and physiology of the mammalian SCN circadian clock.

Animals↗

PubMed1997

Non-peptide glycoprotein IIb/IIIa inhibitors. 17. Design and synthesis of orally active, long-acting non-peptide fibrinogen receptor antagonists.

The synthesis and pharmacological evaluation of 5 (L-738, 167), a potent, selective non-peptide fibrinogen receptor antagonist is reported. Compound 5 inhibited the aggregation of human gel-filtered platelets with an IC50 value of 8 nM and was found to be > 33000-fold less effective at inhibiting the attachment of human endothelial cells to fibrinogen, fibronectin, and vitronectin than it was at inhibiting platelet aggregation. Ex vivo platelet aggregation was inhibited by > 85% 24 h after the oral administration of 5 to dogs at 100 micrograms/kg. The extended pharmacodynamic profile exhibited by 5 appears to be a consequence of its high-affinity binding to GPIIb/IIIa on circulating platelets and suggests that 5 is suitable for once-a-day dosing.

Adenosine Diphosphate↗

PubMed1997

Cellular localization of tumor necrosis factor mRNA in neurological tissue from HIV-infected patients by combined reverse transcriptase/polymerase chain reaction in situ hybridization and immunohistochemistry.

HIV-induced neurological disease is postulated to be caused by indirect mechanisms. Tumor necrosis factor (TNF)alpha is increased in the brains in human immunodeficiency virus (HIV)-associated dementia and in the spinal cord in vacuolar myelopathy and may play a pathogenetic role in these diseases. Microglia, astrocytes and infiltrating macrophages can be induced to produce TNF alpha and each has been identified as a source of TNF alpha in neurological disease. Reverse transcriptase synthesis of cDNA and polymerase chain reaction amplification of the cDNA was combined with immunocytochemistry to identify the cellular source of TNF alpha in HIV-induced neurological disease. Cells positive for TNF alpha mRNA were more abundant in white matter than gray matter of the brain from demented individuals. TNF alpha mRNA-positive cells in brains and spinal cords were almost exclusively macrophage-lineage cells. Only rare TNF alpha mRNA-positive cells were astrocytes. We conclude that macrophage-lineage cells are the primary source of elevated central nervous system TNF alpha mRNA in providing further evidence that macrophage activation is an important element in the pathogenesis of HIV-associated neurological disease.

Animals↗

PubMed1997

Transforming growth factor-beta1 in adult human microglia and its stimulated production by interleukin-1.

Ameboid microglia express human immunodeficiency virus 1 (HIV-1) more frequently than do ramified microglia. These two microglial subtypes might also differ in the frequency with which they express transforming growth factor-beta1 (TGF-beta1), a cytokine that regulates HIV-1 expression in monocytes. Results described here show that ameboid and ramified microglia express TGF-beta1. In brain tissues from HIV-1-infected individuals as compared with seronegative controls, ameboid rather than ramified microglia more frequently expressed TGF-beta1. Ameboid microglia, isolated and cultured from postmortem adult human brain more frequently expressed TGF-beta1 in presence of interleukin-1(IL-1), a cytokine that is elevated in brains of HIV-1-infected individuals when compared with seronegative controls. The stimulation of TGF-beta1 by IL-1 was dose and time dependent, occurring with ameboid microglia isolated from either frontal cortex or globus pallidus but not midbrain pons. Ameboid microglia are similar to the RCA-1-positive cells that form clusters, called microglial nodules, in the brain of HIV-1-infected individuals. Pathologic conditions, such as disseminated microglial nodules, are associated with HIV-1 encephalitis, direct infection of the brain, and moderate to severe neurologic impairment. TGF-beta1 expression in ameboid microglia may play a role in HIV-1 neuropathogenesis.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Nonpeptide glycoprotein IIb/IIIa inhibitors. 15. Antithrombotic efficacy of L-738,167, a long-acting GPIIb/IIIa antagonist, correlates with inhibition of adenosine diphosphate-induced platelet aggregation but not with bleeding time prolongation.

The nonpeptide platelet glycoprotein IIb/IIIa antagonist, L-738, 167, was characterized in dog and nonhuman primate. In an anesthetized canine model of coronary artery electrolytic lesion, L-738,167 elicited dose-dependent (3, 4, 4.5 and 5 micrograms/kg i.v.) decreases in incidence of occlusion, reductions in thrombus mass and elevations in bleeding time. Antithrombotic efficacy correlated with inhibition of adenosine diphosphate-induced platelet aggregation but was dissociated from marked bleeding time elevation. Similarly, suppression of platelet-dependent cyclic flow reductions with L-738,167 in the canine coronary artery (5 micrograms/kg i.v.) and African green monkey carotid artery (10 micrograms/kg i.v.) correlated with inhibition of adenosine diphosphate-induced platelet aggregation but not with inhibition of thrombin-induced platelet aggregation or significant prolongation of bleeding time. In conscious dogs and sedated chimpanzees, single dose intravenous bolus (5-20 micrograms/kg) and oral (25-200 micrograms/kg) administration of L-738,167 exhibited long duration (> or = 8 hr) inhibition of ex vivo platelet aggregation. Once daily oral administration to conscious dogs (10-30 micrograms/kg/day for 15 days) and rhesus monkeys (200-250 micrograms/kg/day for 11 days) maintained significant but submaximal (50-90% inhibition) trough levels of inhibition of adenosine diphosphate-induced ex vivo platelet aggregation. Platelet sensitivity to adenosine diphosphate after multiple days of oral dosing in dogs was similar to pretreatment sensitivity. L-738,167 showed characteristics suitable for chronic oral therapy with a glycoprotein IIb/IIIa inhibitor.

Adenosine Diphosphate↗

PubMed1996

Immunologic NO synthase: elevation in severe AIDS dementia and induction by HIV-1 gp41.

Indirect mechanisms are implicated in the pathogenesis of the dementia associated with human immunodeficiency virus-type 1 (HIV-1) infection. Proinflammatory molecules such as tumor necrosis factor alpha and eicosanoids are elevated in the central nervous system of patients with HIV-1-related dementia. Nitric oxide (NO) is a potential mediator of neuronal injury, because cytokines may activate the immunologic (type II) isoform of NO synthase (iNOS). The levels of iNOS in severe HIV-1-associated dementia coincided with increased expression of the HIV-1 coat protein gp41. Furthermore, gp41 induced iNOS in primary cultures of mixed rat neuronal and glial cells and killed neurons through a NO-dependent mechanism. Thus, gp41-induced NO formation may contribute to the severe cognitive dysfunction associated with HIV-1 infection.

AIDS Dementia Complex↗

PubMed1996

Non-peptide glycoprotein IIb/IIIa antagonists. 11. Design and in vivo evaluation of 3,4-dihydro-1 (1H)-isoquinolinone-based antagonists and ethyl ester prodrugs.

The structure-activity relationship of a series of orally active glycoprotein IIb/IIIa antagonists containing a nitrogen heterocycle grafted onto a 3,4-dihydro-1 (1H)-isoquinolinone core is described. These compounds are structurally novel analogs of the progenitor compound 1 (L-734,217,[[3(R)-[2-(piperidin-4-yl)ethyl]-2-oxopiperidinyl ]acetyl]-3(R)- methyl-beta-alanine) in which the lactam chiral center has been removed. The 4-piperazinyl- and 4-piperidinyl-substituted 3,4-dihydro-1(1H)-isoquinolinones were found to be optimal for in vitro potency. In addition, substitution at the 3-position of the beta-amino acid enhanced potency with the 3-pyridyl and 3-ethynyl analogs being the most potent prepared. Attempts to improve the in vivo profile of these compounds focused on modification of the physical properties. Ester prodrugs were prepared to increase the lipophilicity and remove the zwitterionic nature of the antagonists. The prodrug approach, coupled with the arylpiperazine terminus (pKa = approximately 9.0), afforded moderately basic and relatively nonpolar compounds. The acid N-[[7-(piperazin-1-yl)-3,4-dihydro-1(1H)-oxoisoquinolin-2-yl ]acetyl]-3(S)- ethynyl-beta-alanine, 6d (L-767,679), is a potent fibrinogen receptor antagonist able to inhibit the ADP-induced aggregation of human gel-filtered platelets with an IC50 of 12 nM. Although 6d is orally active based on the results of an ex vivo dog assay at 0.3 mg/kg, the ethyl ester prodrug of this compound, 19 (L-767,685), is better absorbed at this dose than 6d. Upon oral dosing, the ester 19 is converted to 6d in vivo in dog with an estimated oral systemic availability of > 17% (0-8 h, AUC19po/AUC6div). In addition, studies in monkey at an oral dose of 1 mg/kg show that 19 affects the complete inhibition of the ex vivo platelet aggregation in response to ADP between 2 and 8 h postdose with the level of inhibition remaining at 40% at 12 h postdose. This level of activity was superior to that observed for 6d and 1 at the same dose. Using ex vivo ADP-induced aggregation data from rhesus monkey (n = 2, 0-8 h using the AUC19po/AUC6div), the estimated systemic oral availability of 6d when dosed as 19 is 32%.

Animals↗

PubMed1996

Pharmacokinetics of extracellular melatonin in Siberian hamster forebrain.

In vivo brain microdialysis was used to characterize the pharmacokinetics of subcutaneously injected melatonin in the anterior hypothalamic-preoptic area (AH-POA) of the male Siberian hamster. Animals with a microdialysis probe implanted in the AH-POA were treated with a subcutaneous melatonin injection at 0900 h (3 h after lights-on) or 2000 h (2 h prior to lights-off). Treatment with 2.5 or 0.25 mg/kg dosages of melatonin in saline vehicle induced peak concentrations of melatonin in AH-POA microdialysates within 20 min of injection (165 +/- 34 and 18 +/- 8 pg/20 min, respectively). For the 2.5 and 0.25 mg/kg dosages, the half-life of the absorbed melatonin (t 1/2 elimination) was less than 20 min, and the concentrations fell to baseline within 60 min after injection. There were no significant time of day effects on the kinetic profile of extracellular melatonin associated with either of these dosages. These results confirm the rapid accumulation and clearance of extracellular melatonin in the vicinity of its putative target tissues.

Animals↗

PubMed1996

Investigation of (Oxodioxolenyl)methyl carbamates as nonchiral bioreversible prodrug moieties for chiral amines.

The preparation of (oxodioxolenyl)methyl carbamates and their evaluation as novel nonchiral prodrug moieties for chiral primary and secondary amino functional drugs are described. 4-(Carbamoylmethyl)-2-oxo-1,3-dioxolene derivatives of 3,4-dimethoxyphenethylamine with 5-methyl, 5-phenyl, and 5-anisyl substitution (5a, 5b, and 5c) on the dioxolenone ring were prepared as model amine prodrugs by a one step process involving displacement of p-nitrophenol from appropriately substituted ring opening of these carbamates led to a cascade reaction resulting in the rapid and quantitative regeneration of the parent amine drug. Aryl substitution did not significantly alter the hydrolysis rates of these dioxolenone carbamates in buffers at pH 1 and 7.4 or in rat plasma, although the hydrolysis rates of 5-phenyl- (1b) and 5-anisyl- 4-methyl-1,3-dioxol-4-en-2-one (1c) in pH 7.4 phosphate buffer were 2-3 fold faster than that of the 5-methyl-substituted analog (1a). Application of this prodrug strategy to the chiral fibrinogen receptor antagonist L-734,217 resulted in a prodrug that gave quantitative reconversion in rat and dog plasma in vitro and oral bioavailability of 23 +/- 6% in dogs for the parent drug.

Amines↗

PubMed1996

Quantitation of human immunodeficiency virus in brains of demented and nondemented patients with acquired immunodeficiency syndrome.

We measured human immunodeficiency virus (HIV) DNA in brains of 15 patients who died with acquired immunodeficiency syndrome (AIDS). All had been followed prospectively prior to death; 7 were demented and 8 were not demented. HIV was detected in 13 of 15 brains by polymerase chain reaction (PCR) and in the remaining 2 by presence of viral RNA or viral antigen. Quantitative PCR showed a wide range in amounts of HIV DNA with no significant difference between brains of demented and nondemented patients. These results suggest that qualitative features of the virus, rather than increased virus load per se, may be responsible for the clinical differences between HIV-infected patients with and without dementia.

AIDS Dementia Complex↗

PubMed1996

Localization of HIV-1 in human brain using polymerase chain reaction/in situ hybridization and immunocytochemistry.

Human immunodeficiency virus type 1 (HIV-1) infects the brains of a majority of patients with the acquired immunodeficiency syndrome (AIDS), and has been linked to the development of a progressive dementia termed "HIV-associated dementia." This disorder results in severe cognitive, behavioral, and motor deficits. Despite this neurological dysfunction, HIV-1 infection of brain cells does not occur significantly in neurons, astrocytes, or oligodendrocytes, but is restricted to brain macrophages and microglia. To identify possible low-level or latent infection of other brain cells, we combined the techniques of the polymerase chain reaction with in situ hybridization for the detection of HIV DNA, and used immunocytochemistry to identify the HIV-expressing cells. In the 21 adult brains studied (15 AIDS and 6 seronegative control brains), we found that polymerase chain reaction/in situ hybridization was both sensitive and specific for identifying HIV-infected cells. In all brains, the majority of infected cells were macrophages and microglia. In several brains, however, a substantial minority of cells harboring HIV DNA were identified as astrocytes. Neurons, oligodendrocytes, and endothelial cells were not infected with HIV, even in cases with HIV-associated dementia. These findings confirm previous data regarding the importance of macrophage/microglial infection, and essentially exclude neuronal infection in pathogenetic models of HIV-associated neurological disease. These data also demonstrate that latent or low-level infection of astrocytes occurs in AIDS, a finding that may be of importance in understanding HIV neuropathogenesis.

Adult↗

PubMed1996

Human immunodeficiency virus and the brain.

Human immunodeficiency virus (HIV) infects the nervous system in the majority of patients, causing a variety of neurological syndromes throughout the course of the disease. This review focuses on the effects of HIV in the central nervous system, with an emphasis on HIV-associated dementia. HIV-associated dementia occurs in a subset of patients with AIDS; it is unclear why these patients and not all patients develop the disease. Several factors are likely to be involved in the pathogenesis of HIV-associated dementia, including neurotoxins released from the virus and/or infected macrophages and microglia, immunologic dysregulation of macrophage function, and specific genetic strains of HIV. These factors, and their possible interactions, are discussed.

AIDS Dementia Complex↗

PubMed1996

"BM180": a novel basement membrane protein with a role in stimulus-secretion coupling by lacrimal acinar cells.

Regulated secretion requires the developmental coupling of neuronal or hormonal stimuli to an exocytotic response, a multistep pathway whose appearance may be linked with cellular adhesion to the newly formed exocrine cell basement membrane. We screened for adhesion-associated coupling activity using lacrimal acinar cells and have identified "BM180", a novel basement membrane protein enriched in guanidine HCl extracts of lacrimal and parotid exocrine secretory glands. BM180 resides primarily in a previously inexamined lower molecular-mass basement membrane peak (peak 2) that contains cell adhesion activity inhibitable with the anti-BM180 monoclonal antibody 3E12. Removal of peak 2 by gel filtration or preincubation of basement membrane with 3E12 decreased regulated peroxidase secretion by one-half without affecting constitutive secretion or the amount of cellular peroxidase available for release. Adding back peak 2 restored regulated secretion in a dose-dependent and 3E12-inhibitable manner and suggested a synergistic relationship between BM180 and laminin 1. BM180 has a mobility of 180 and 60 kDa in the absence or presence of dithiothreitol, respectively, and shows no immunological identity by competitive enzyme-linked immunosorbent assay with laminin 1, collagen IV, entactin, fibronectin, BM-40, perlecan, or vitronectin. We propose that BM180 is an important resident of certain glandular basement membranes where it interacts with the cell surface, thereby possibly signaling the appearance of a transducing element in the stimulus-secretion coupling pathway.

Animals↗

PubMed1996

Stereological analysis of cerebral atrophy in human immunodeficiency virus-associated dementia.

Brain atrophy is a common finding in patients with AIDS, but the relationship of atrophy to HIV-associated dementia is unclear. We used unbiased, stereological methods on postmortem brain specimens to estimate volumes of different brain regions in patients prospectively diagnosed with and without HIV-associated dementia. Thirty HIV-seropositive (9 without AIDS/without dementia, 6 with AIDS/without dementia, 15 with AIDS/with dementia) and 7 HIV-seronegative controls were studied using the technique of point counting and Cavalieri's principle of volume estimation. There was a significant reduction in the mean neocortical volume (15%, p = 0.032) in the group with AIDS when compared to the seronegative controls, and this difference was accentuated when comparing only the group with HIV-associated dementia to the seronegatives (neocortex: 18%, p = 0.020). There were no significant differences between the AIDS groups with and without HIV-associated dementia, although there was a trend for smaller volumes in the most severely demented patients. There were no differences in white matter volumes between groups. In conclusion, patients dying with AIDS and particularly those with HIV-associated dementia, show significant neocortical atrophy when compared to seronegative controls. The lack of a significant difference in cerebral atrophy between HIV-seropositive patients with and without dementia suggests that atrophy may be a more generalized phenomenon of AIDS as opposed to a specific marker for HIV-associated dementia.

AIDS Dementia Complex↗

PubMed1995

Photoperiod affects the expression of neural cell adhesion molecule and polysialic acid in the hypothalamus of the Siberian hamster.

Immunohistochemical and immunoblot procedures were used to examine the effects of inhibitory short day (SD) photoperiod on the expression of neural cell adhesion molecule (NCAM) and its polysialylated form (PSA-NCAM) in the hypothalamus and preoptic area (POA) of the adult male Siberian hamster. In animals that had undergone SD-induced gonadal regression, immunoblot analyses revealed significant reductions in the content of immunoreactive PSA in anterior hypothalamic (AH) and mediobasal hypothalamic (MBH) regions. These changes were accompanied by increased contents of the 180 kDa NCAM isoform in the POA and AH, and decreased content in the MBH. The 140 kDa NCAM isoform also was elevated in the AH. Light microscopic analysis revealed a marked reduction in the density of NCAM-immunoreactive tanycyte-like processes in the MBH of animals exposed to SD. This effect was not blocked by castration, indicating that this may be a primay (sex steroid-independent) effect of altered photoperiod in the hypothalamus. Also, photoperiod-induced alterations in NCAM expression were not evident in non-responsive hamsters that maintained active testes under SD exposure. Collectively, these results are evidence that seasonal changes in photoperiod affect the expression of NCAM and PSA in the hypothalamus. Such changes could help promote plastic morphological rearrangements related to the regulation of seasonal reproductive and/or metabolic cycles.

Analysis of Variance↗

PubMed1995

Serotonergic potentiation of photic phase shifts of the circadian activity rhythm.

Recent evidence suggests that serotonin may function to regulate the sensitivity of the circadian clock to the resetting effect of environmental light. Here we report that systemic administration of NAN-190, a drug that acts at both postsynaptic and somatodendritic serotonin receptors, potentiates light-induced phase shifts by as much as 250%. The effects of the drug are dose-related and are significant at light intensities between 0.2 and 200 lux. It is proposed that drugs with pharmacological properties similar to NAN-190 may prove useful as chronobiologics to adjust the sensitivity of the circadian system to natural 'zeitgebers'.

Animals↗

PubMed1995

Immunocytochemical quantitation of human immunodeficiency virus in the brain: correlations with dementia.

The pathogenesis of human immunodeficiency virus (HIV)-associated dementia is unclear, and the underlying pathological substrate has been a matter of debate. In a prospectively clinically characterized population of acquired immunodeficiency syndrome (AIDS) patients we investigated the relationship between the clinical syndrome of HIV-associated dementia and the presence and relative quantity of immunocytochemical markers for HIV-1 (gp41 antibody), and for macrophages and microglia (HAM-56 antibody). Sections from the basal ganglia and frontal lobes from the brains of 51 patients were studied, and the data were stratified for severity of dementia (16 nondemented, 12 mildly demented, 23 severely demented), rate of dementia progression, duration of AIDS, use of antiretrovirals, and several other demographic features. We found a highly significant correlation between the degree of macrophage staining and the severity of dementia but only a borderline correlation between the presence and amount of gp41-positive cells and dementia. Several nondemented patients showed abundant gp41 immunoreactivity, and some severely demented showed little to no gp41 immunoreactivity. Other correlations with the immunostaining data, including antiretroviral use, were not significant. We conclude that the presence of macrophages and microglia is a better correlate with HIV-associated dementia than is the presence and amount of HIV-infected cells in the brain. These data support the concept that the pathogenesis of HIV-associated dementia is likely due to indirect effects of HIV infection of the brain, possibly through the actions of macrophages and microglia.

AIDS Dementia Complex↗

PubMed1995

A potential role for interferon-alpha in the pathogenesis of HIV-associated dementia.

Previous studies in patients receiving interferon-alpha (IFN-alpha) therapy and patients with systemic lupus erythematosus have demonstrated that elevated cerebrospinal fluid (CSF) levels of IFN-alpha are associated with cognitive dysfunction. We measured IFN-alpha levels in CSF and blood by ELISA in human immunodeficiency virus (HIV)-positive patients with (n = 21) and without (n = 23) dementia and HIV-negative controls (n = 48). IFN-alpha was significantly elevated in the CSF of HIV-positive patients with dementia compared to those without dementia and controls. An increasing amount of IFN-alpha in the CSF was correlated with the clinical parameter of increasing Memorial Sloan Kettering scores; although these correlations were not statistically significant, they further suggest an association of increased CSF IFN-alpha with neurocognitive dysfunction in AIDS. Immunocytochemical staining of brains demonstrated IFN-alpha-positive macrophages and astrocytes in frontal cortex and white matter and IFN-alpha mRNA was detected by reverse transcriptase-polymerase chain reaction, further indicating that IFN-alpha is made by cells within the brain and suggesting that the significant increases of IFN-alpha protein found in the CSF of patients with HIV-associated dementia complex are derived from intrinsic brain cells such as macrophages and astrocytes. Increased local production of IFN-alpha during HIV infection may contribute directly or indirectly to the pathogenesis of HIV-associated dementia.

AIDS Dementia Complex↗