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Biomedical subjects

J D Glass

Publications and source records attributed to J D Glass.

At least 37 records · Page 2Linked to original sources
PubMed2000

Recombinant chimeric Borrelia proteins for diagnosis of Lyme disease.

Current serologic Lyme disease tests use whole borrelia cells as the source of antigen. These assays are difficult to standardize and to optimize for sensitivity and specificity. To help solve these problems, we constructed a library of recombinant chimeric proteins composed of portions of key antigens of Borrelia burgdorferi. These proteins were then used to develop an enzyme-linked immunosorbent assay. We compared our assay with the most sensitive of three whole-cell borrelia assays. We found that the recombinant assay could detect antibodies significantly better from early Lyme disease sera (P<0.05), and had the same sensitivity for late Lyme disease sera, as the most sensitive whole-cell borrelia assay. On potentially cross-reactive sera, the recombinant assay was more specific, but not significantly so, than the best whole-cell borrelia assay. Optimization of the recombinant assay offers the potential for a significant improvement in both sensitivity and specificity.

Antibodies, Bacterial↗
PubMed1999

Ultrastructural analysis of polysialylated neural cell adhesion molecule in the suprachiasmatic nuclei of the adult mouse.

The suprachiasmatic nuclei (SCN) of the anterior hypothalamus are recognized as the principal circadian clock in mammals. The adult SCN express a high level of polysialylated neural cell adhesion molecule (PSA-NCAM), a cell surface sialoglycoprotein capable of modulating cell-cell interactions. In the present study, the expression of PSA-NCAM in the mouse SCN was studied at the ultrastructural level by immunolabeling using monoclonal antibodies against the polysialic acid (PSA) moiety of PSA-NCAM. We showed that neuronal somal expression of PSA-NCAM was distributed heterogeneously in the SCN, with extensive staining of somas in the central region of the SCN, and minimal somal staining in the ventral portion of the nuclei. In contrast, immunoreactive neuropil, including unmyelinated fine axon fascicles was distributed throughout the SCN. The PSA-NCAM was also detected adjacent to synaptic junctions by both immunoperoxidase and immunogold techniques. For astrocytes, immunostaining of somas and larger processes was sparse, but staining was profuse along fine processes. Immunostained fine astrocytic processes were frequently observed between apposing neuronal somas, and in close association with synaptic junctions and small blood vessels. These findings, together with the demonstrated role of PSA-NCAM in modulating cell-cell interactions in other brain regions support a role for PSA-NCAM in regulating cell-cell interactions in the SCN.

Animals↗
PubMed1999

Axonal neurofilaments are resistant to calpain-mediated degradation in the WLD(S) mouse.

The biological basis for the phenotype of delayed Wallerian degeneration in the WLDs mouse has yet to be elucidated, although it is known that the characteristic is intrinsic to the axon. Previous data suggested that nerves from the WLD(S) are relatively resistant to proteolytic degradation. We investigated the time-course of neurofilament degradation in response to addition of the calcium-activated protease m-calpain, comparing nerves from WLD(S) and wild-type mice. During 10 min of in vitro proteolysis, neurofilaments from the WLD(S) were consistently slower to degrade than were neurofilaments from wild-type mice. Direct comparisons were performed on Western blots, with statistically significant differences in neurofilament immunoreactivity at 2, 4, and 6 min of reaction time (p < 0.01). These findings suggest that the mutation leading to the WLD(S) phenotype may affect the proteolytic interaction between calpain and neurofilaments.

Animals↗
PubMed1999

Nonpeptide glycoprotein IIB/IIIA inhibitors. 19. A new design paradigm employing linearly minimized, centrally constrained, exosite inhibitors.

A new series of potent, linearly-minimized, orally active, selective GPIIb/IIIa inhibitors is identified. Thus 15 (L-750,034) achieves interaction via a constrained, non-turned conformation that maintains the proper distance between its charged termini and full sulfonamide exosite interaction. The diminutive stature and the proposed linear conformation of L-750,034 define a new paradigm for the conceptualization of RGD mimics.

Benzamides↗
PubMed1999

Generation of spectrin breakdown products in peripheral nerves by addition of M-calpain.

Identification of spectrin breakdown products (SBP) in tissues of the central nervous system (CNS) has been used to monitor calpain activity in models of neurodegeneration. We investigated the use of this technique in the peripheral nervous system (PNS) in order to use it as a marker of calpain-mediated proteolysis during axonal degeneration. Using in vitro methods for activation of calpains, we compared brains and sciatic nerves from rats for the presence of calpain-specific SBP. The 150-kDa SBP identified on western blots was demonstrated in brain and nerve homogenates subjected to membrane disruption in the presence of calcium. Incubation of tissues with recombinant m-calpain generated SBP in a dose-dependent fashion, and calpastatin inhibited the generation of SBP by either paradigm. In contrast to brain, sciatic nerves showed the presence of SBP even in noninjured tissues, suggesting a basal level of calpain activity in peripheral nerves. Time-course experiments showed that the generation of SBP in sciatic nerves correlated with the breakdown of axonal neurofilaments. SBP peaked within minutes after addition of m-calpain and disappeared in the homogenates before 1 h, indicating that identification of SBP is a transient phenomenon. These data provide a potential new way for studying axonal degeneration in both experimental and human neuropathies.

Animals↗
PubMed1999

Serotonergic modulation of astrocytic activity in the hamster suprachiasmatic nucleus.

The present study was undertaken to explore the effects of central serotonin receptor activation on the expression of glial fibrillary acidic protein in the suprachiasmatic nucleus of Syrian hamsters. Immunoblot and immunohistochemical procedures were used to examine the effects of systemic application of the serotonin-1A and serotonin-7 receptor agonist, (+/-)-2-dipropyl-amino-8-hydroxyl-1,2,3,4-tetrahydronaphthalene hydrobromide (8-OH-DPAT; 3.75 mg/kg) on the contents and distribution of glial fibrillary acidic protein in the suprachiasmatic nucleus. Administration of 8-OH-DPAT at midday caused a significant reduction in immunoreactive glial fibrillary acidic protein content within 1 h of injection, compared to vehicle controls. This effect was not evident 3 h after drug injection. Treatment with 8-OH-DPAT during the late dark phase had little effect on glial fibrillary acidic protein content. The 8-OH-DPAT-induced reduction in glial fibrillary acidic protein content seen at midday was blocked partially by pretreatment with the serotonin-2 and serotonin-7 receptor antagonist, ritanserin, and more substantially by pretreatment with the serotonin-1A receptor antagonist, NAN-190. Treatment with 8-OH-DPAT also caused a significant redistribution of immunoreactive glial fibrillary acidic protein, such that the dense mesh-like appearance seen in vehicle controls was significantly reduced. The 8-OH-DPAT treatment also significantly decreased expression of polysialic acid, a cell-surface molecule associated with neural plasticity. Immunoblot assessments of glial fibrillary acidic protein contents 2 h before and 1 h after lights off revealed a significant time-of-day difference in glial fibrillary acidic protein expression, with lowest levels occurring at the latter time-point, associated with maximal endogenous serotonin release in the suprachiasmatic nucleus. Collectively, these results indicate that acute plastic changes in glial fibrillary acidic protein-related astrocytic activity in the suprachiasmatic nucleus can be induced in response to serotonin-7 or serotonin-1A receptor activation in a phase-dependent manner. It is interesting to speculate that circadian reorganizations in astrocytic activity could be regulated by the daily rhythm in serotonin release in the suprachiasmatic nucleus.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1999

In vivo assessment of the midbrain raphe nuclear regulation of serotonin release in the hamster suprachiasmatic nucleus.

Serotonin (5-HT) plays important regulatory roles in mammalian circadian timekeeping; however, little is known concerning the regulation of serotonergic activity in the circadian clock located in the suprachiasmatic nuclei (SCN). By using in vivo microdialysis to measure 5-HT release we demonstrated that electrical or pharmacological stimulations of the dorsal or median raphe nuclei (DRN and MRN, respectively) can alter basal release of 5-HT in the hamster SCN. There were similar increases in SCN 5-HT release after electrical stimulation of either the MRN or DRN, indicating that both could contribute to the serotonergic activity in the SCN. Systemic pretreatment with the 5-HT antagonist metergoline abolished DRN-induced SCN 5-HT release but had little effect on MRN-induced SCN 5-HT release, suggesting different pathways for these nuclei in regulating 5-HT output in the SCN. Microinjections of the 5-HT1A autoreceptor agonist 8-OH-DPAT or antagonist WAY 100635 into the MRN caused significant inhibition and stimulation of SCN 5-HT release, respectively. Both drugs had substantially less effect in the DRN. These differential drug actions indicate that somatodendritic 5-HT1A autoreceptors on MRN neurons provide the prominent raphe autoregulation of 5-HT output in the SCN. Collectively the current results are evidence that DRN as well as MRN neurons can contribute to the regulation of 5-HT release in the hamster SCN. On the basis of the current observations and those from recent anatomic tracing studies of serotonergic projections to SCN it is hypothesized that DRN input to the SCN could be mediated by a DRN --> MRN --> SCN pathway involving a 5-HT-sensitive multisynaptic interaction between the DRN and MRN neurons.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1998

The nephritogenic T cell response in murine chronic graft-versus-host disease.

To investigate mechanisms of cell-mediated events in chronic glomerulonephritis, T cell clones were isolated from kidneys of animals with murine chronic graft-vs-host disease. This systemic disorder is induced in normal (C57BL/6 x DBA/2)F1 recipients (H-2b/d) following transfer of parental (DBA/2) T cells (H-2d). These studies demonstrate that mouse renal (MR) T cells isolated from nephritic kidneys of diseased recipients are host-derived CD4+ alpha/beta+ T cells. Adoptive transfer of a panel of MR clones to naive (C57BL/6 x DBA/2)F1 recipients reveals distinct functional subsets. One subset does not transfer renal disease, and one induces severe renal inflammation and damage. In vitro proliferative responses of nephritogenic MR clones reveal predominant reactivity toward autologous class II MHC (I-Ed/I-Ad) determinants, and selected nephritogenic MR clones preferentially recognize renal Ag preparations derived from normal (C57BL/6 x DBA/2)F1 kidneys. In addition, cytokine profile analysis of MR clones indicates a Th2 pattern with IL-4 and IL-10 expression, although nephritogenic T cell clones also express IFN-gamma. These data suggest that the nephritogenic T cell response in chronic graft-vs-host disease is autoreactive in nature and may be restricted by determinants shared by both graft and host (Iad).

Animals↗
PubMed1998

Endogenous regulation of serotonin release in the hamster suprachiasmatic nucleus.

Serotonin (5-HT) has been strongly implicated in the regulation of the mammalian circadian clock located in the suprachiasmatic nuclei (SCN). However, little is known of the pattern of neuronal 5-HT release in the SCN or of the factors involved in regulating its release. Using in vivo microdialysis, we demonstrated the existence of a daily rhythm in the output of 5-HT in the SCN of freely behaving hamsters. This rhythm was characterized by a sharp increase in release from a nadir during late midday to peak levels at the light/dark transition. Output declined to basal levels throughout the remainder of the night. A similar pattern also was evident under constant darkness, with increased 5-HT output occurring at the onset of subjective night. Locomotor activity induced by exposure to a novel running wheel had a pronounced phase-dependent effect on 5-HT release in the SCN, with stimulation during the light phase and suppression during the late dark phase. Systemic application of the somatodendritic 5-HT1A agonist BMY 7378 had a significantly greater suppressive effect on 5-HT release in the SCN during the late dark phase compared with mid light phase, indicating that a variation in raphe autoreceptor response may underlie the time-dependent effects of wheel running on 5-HT release. Collectively, these results show that the daily rhythm in output of 5-HT in the SCN is generated endogenously, and that behavioral state can strongly influence serotonergic activity in the circadian clock in a phase-dependent manner.

Animals↗
PubMed1998

Cloning of m-calpain 80 kD subunit from the axonal degeneration-resistant WLD(S) mouse mutant.

Calpains are calcium-activated cysteine proteases that are involved in cellular degradation in models of neurodegeneration. Calpains are the effectors of cytoskeletal disruption during axonal degeneration, a pathological feature of many neurological disorders. The WLD(S) mouse mutant is resistant to axonal degeneration and demonstrates prolonged survival of the cytoskeleton after nerve injury. To investigate the possibility that a mutation in calpain or abnormalities in calpain protein expression is responsible for the resistance to axonal degeneration seen in the WLD(S) mouse mutant, we 1) cloned and sequenced the large subunit of the high calcium-requiring form of calpain (m-calpain) from nervous system tissues of WLD(S) and from wild-type C57BL/6 mice, and 2) generated polyclonal m-calpain antibodies for comparison of relative protein levels by Western blot. We found our sequence for mouse m-calpain to be almost identical to another recently published mouse sequence, and the wild-type and WLD(S) sequences to be identical. Our fusion protein and peptide polyclonal antibodies were specific for the 80 kD subunit and recognized appropriate protein bands from pure m-calpain, fusion protein, and in tissue. There was no apparent difference in m-calpain expression in nerve or spinal cord in noninjured adult animals. These data suggest that a defect in m-calpain 80 kD subunit does not likely underlie the WLD(S) phenotype, but raise questions about other subunits of calpain and possibly other proteases.

Amino Acid Sequence↗
PubMed1998

Role of laminin-1, collagen IV, and an autocrine factor(s) in regulated secretion by lacrimal acinar cells.

Adhesion to novel basement membrane component BM180 in the presence of laminin-1 promotes stimulus-secretion coupling in lacrimal acinar cells [G. W. Laurie, J. D. Glass, R. A. Ogle, C. M. Stone, J. R. Sluss, and L. Chen. Am. J. Physiol. 270 (Cell Physiol. 39): C1743-C1750, 1996]. The identity of the active laminin-1 site and the possibility that other promoters of coupling are present in the acinar cell microenvironment were probed by use of different substrates, media, neutralizing antibodies and cell numbers. Regulated peroxidase secretion was unaffected by basement membrane coat concentration and was detectable at reduced levels in serum-free medium. Anti-laminin-1 antibodies, particularly against sites in the beta1 and gamma1 chains, but not alpha1 chains, partially suppressed regulated secretion, as did an anti-collagen IV antibody. Without effect were RGD peptide and antibodies against entactin, the beta1-integrin subunit, and several growth factors. Increasing cell number in serum-free medium revealed an unknown, serum-maskable, secretion-enhancing activity with a remarkable specificity for regulated secretion. Stimulus-secretion coupling, therefore, appears to be modulated by several extracellular factors whose relative contributions remain to be determined.

Animals↗
PubMed1998

Variable progression of HIV-associated dementia.

A consecutive series of 71 patients diagnosed with HIV-associated dementia (HAD) (1984-1994) were studied to characterize the clinical course of HAD, and to identify predictive markers of rapid neurologic progression. Neurologic progression rate was determined from the change in the Memorial Sloan Kettering (MSK) dementia severity score from diagnosis to death. Those with the most rapid progression in neurologic disability were compared with those with slow or no progression. Autopsy material was immunostained for macrophage activation markers and gp41 in 30 individuals. Median survival was 3.3 months and 6.1 months for rapid-progression and no-progression patients, respectively. Rapid progression was associated with injection drug use but not with race, gender, or age. CD4+ cell counts were lower at diagnosis among rapid-progression than no-progression patients but no differences in AIDS-defining illnesses or patterns of antiretroviral therapy were found. At presentation, rapid-progression patients had more prominent symptoms of mental slowing than those with no progression; however, no other clinical features, CSF, or imaging features distinguished the groups. Less abundant macrophage activation in both basal ganglia and midfrontal gyrus regions, as judged by HAM56 immunostaining, was noted in 9 no-progression patients, compared with 12 rapid-progression patients. Neurologic progression and survival with HAD is highly variable. A significant proportion of individuals with dementia have prolonged survival of more than 12 months and remain cognitively stable. A history of injection drug use and presentation with prominent psychomotor slowing is associated with more rapid neurologic progression, and these patients tend to show more abundant macrophage activation within the CNS.

AIDS Dementia Complex↗
PubMed1998

Brain-derived HIV-1 tat sequences from AIDS patients with dementia show increased molecular heterogeneity.

HIV-1 infection results in a dementing illness affecting 20% of patients with AIDS. Several HIV-1 genes have been implicated in the pathogenesis of HIV-induced neurological disease. To search for distinct HIV-1 sequences associated with the development of dementia, brain-derived tat, env, and pol sequences were examined from AIDS patients defined pre-mortem as demented (HIV-D)[n=5] or non-demented (HIV-ND)[n=5]. Estimations of evolutionary distances and frequency of non-synonymous mutation rates revealed significant differences between brain-derived tat, env, and pol-encoded reverse transcriptase sequences. However, established zidovudine-associated resistance mutations in reverse transcriptase sequences were identified in only one HIV-D and one HIV-ND patient despite prolonged treatment of some patients. Non-synonymous/synonymous substitution rates among the tat sequences derived from patients with HIV-D were significantly higher compared to the HIV-ND group (P < 0.001). The ratios of transversions to transitions were also significantly higher among the HIV-D tat sequences (P< 0.01). Phylogenetic analyses showed clustering of sequences from each clinical group among the brain-derived tat and env sequences. These studies indicated that differing selective forces act on individual HIV-1 genes in the brain which may influence the development of dementia.

AIDS Dementia Complex↗
PubMed1997

Nonpeptide glycoprotein IIb/IIIa inhibitors: 14: oral antithrombotic efficacy of L-738,167 in a conscious canine model of coronary artery electrolytic injury.

BACKGROUND: A conscious dog model of left circumflex coronary artery electrolytic injury was used to assess the oral antithrombotic efficacy of L-738,167, a potent nonpeptide antagonist of platelet GP IIb/IIIa. L-738,167 was administered either as a single oral pretreatment dose 2 hours before initiation of vessel injury or as two oral doses administered 24 hours apart, 12 hours before and after initiation of vessel injury. METHODS AND RESULTS: In untreated controls, electrolytic coronary injury (50 microA, 3 hours) resulted in thrombotic occlusion and myocardial ischemia in 15 of 16 dogs, with 4 developing lethal arrhythmias. Significant reductions in thrombus mass and complete prevention of myocardial ischemia and infarction were achieved with a single 100- to 300-microg/kg dose of L-738,167 pretreatment and with two 100-microg/kg doses administered 12 hours before and after initiation of vessel injury. Delays and/or reductions in incidence of ischemia, thrombus mass, and infarct sizes also were achieved with 10- to 30-microg/kg pretreatment and with two 30-microg/kg doses administered 12 hours before and after initiation of vessel injury. None of the L-738,167-treated animals developed lethal arrhythmias. A single oral 100-microg/kg dose of L-738,167 achieved >90% inhibitions of ADP (extent)- and collagen (rate)-induced ex vivo platelet aggregation and fivefold to sixfold or greater elevations in bleeding time; a single oral 30-microg/kg dose of L-738,167 achieved sustained 40% to 70% inhibitions of ADP- and collagen-induced ex vivo platelet aggregation and modest twofold to threefold elevations in bleeding time. At 12 to 24 hours after single oral 30- and 100-microg/kg doses of L-738,167, a substantially greater L-738,167 concentration was associated with platelets than free in plasma. CONCLUSIONS: These findings are indicative of potent and sustained oral antithrombotic efficacy and suggest that L-738,167 possesses potential for the oral management of chronic thrombotic occlusive disorders.

Administration, Oral↗