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Charles Davis

Publications and source records attributed to Charles Davis.

11 recordsLinked to original sources
PubMed2006

Intraventricular insulin and leptin decrease sucrose self-administration in rats.

Data from our laboratory and others have demonstrated an effect of the candidate adiposity signals insulin and leptin to decrease brain reward function, as assessed by lateral hypothalamic self-stimulation and food-conditioned place preference. In this study, we evaluated the effect of centrally administrated insulin or leptin to acutely decrease motivated performance for 5% sucrose, i.e., progressive ratio (PR) sucrose self-administration. Consistent with findings using other behavioral assays, both insulin and leptin significantly decreased the number of bar presses (62+/-7 and 76+/-8% of paired controls respectively), and the number of sucrose rewards obtained (87+/-4 and 91+/-4% of paired controls respectively), relative to within-subjects' control day performance on PR sucrose self-administration, whereas acute intraventricular cerebrospinal fluid had no effect. Rats fed a higher fat diet for 5 weeks were resistant to the effects of the intraventricular insulin or leptin, suggesting a central resistance to their action. Thus the findings of this study extend and support previous observations which suggest that neuroendocrine signals which regulate energy homeostasis in the CNS may also play a role in modulating reward circuitry, and specifically, food reward.

Analysis of Variance↗
PubMed2005

Indirubin-3'-monoxime, a derivative of a Chinese antileukemia medicine, inhibits P-TEFb function and HIV-1 replication.

OBJECTIVE: To evaluate the effects of the cyclin dependent kinase (CDK) inhibitor Indirubin-3'-monoxime (IM) on Tat-mediated transactivation function, a step of the HIV-1 cycle that is not currently targeted in antiviral therapy. METHODS: The effects of IM on CDK implicated in HIV-1 Tat transactivation function were evaluated by kinase assays, transfection experiments, RNase protection assay and RT-PCR analysis of viral transcripts. The antiviral effect of IM was investigated in cells from HIV-1 infected individuals as well as in cell lines, primary lymphocytes and monocyte-derived macrophages. The antiviral activity of IM was also tested against drug-resistant HIV-1. RESULTS: IM inhibits the kinase activity of CDK9 [50% inhibitory concentration (IC50) of 0.05 microM], the catalytic subunit of Positive transcription elongation factor b (P-TEFb). Inhibition of CDK9 activity by IM results in abrogation of Tat-induced expression of HIV-1 RNA in cell lines. In addition, IM inhibits the replication of HIV-1 in both peripheral blood mononuclear cells (IC50 of 1 microM) and macrophages (IC50 of 0.5 microM). IM is effective against primary and drug-resistant strains of HIV-1. Importantly, the antiviral effects of the drug were seen at concentrations that did not affect cell proliferation. CONCLUSIONS: Non-toxic concentrations of IM inhibit HIV-1 by blocking viral gene expression mediated by the cellular factor P-TEFb. The drug is effective against wild-type and drug-resistant strains of HIV-1. IM may help control replication of HIV-1 in patients by disrupting a step of the HIV-1 cycle that is not being targeted in current antiretroviral treatments.

Cyclin-Dependent Kinases↗
PubMed2005

In vitro suppression of latent HIV-1 activation by vitamin E: potential clinical implications.

We evaluated the effect of vitamin E in controlling HIV-1 production upon activation of the patients' reservoir of resting CD4 lymphocytes in tissue culture experiments. The addition of vitamin E to patients' cultures resulted in significantly reduced levels of p24 virus production (P = 0.0015). These results suggest that vitamin E supplementation may interfere with the emergence of drug-resistant HIV-1 variants archived in the resting cell reservoir and delay or limit virus rebound upon treatment interruptions.

Antioxidants↗
PubMed2004

Resveratrol glucuronides as the metabolites of resveratrol in humans: characterization, synthesis, and anti-HIV activity.

Resveratrol is a natural product with diverse biological activities. We have previously reported that resveratrol possesses potent synergistic inhibitory activity against human immunodeficiency virus (HIV)-1 infection in combination with nucleoside analogs (Heredia et al. 2000. J Acquir Immune Defic Syndr 25:246-255). As a part of our program in developing resveratrol as a component for anti-HIV chemotherapy, we describe in this article the characterization, chemical synthesis, and biological effects of the human metabolites of resveratrol. We found that resveratrol was metabolized in humans into two metabolites, which were characterized as resveratrol-3-O- and 4'-O-glucuronides. For further biological studies, we reported two simple, alternative methods for the synthesis of the metabolites. The cytotoxic and antiviral activities of resveratrol and its metabolites were compared in cell culture experiments using human peripheral blood mononuclear cells. Whereas resveratrol was cytotoxic at > or =30 microM, no cytotoxicity was observed for the metabolites at concentrations as high as 300 microM. However, resveratrol showed strong synergistic anti-HIV activity with didanosine at 10 microM, but no synergistic effects were observed for either of the metabolites at up to 300 microM. Nevertheless, the in vitro activity of the metabolites (resveratrol glucuronides) may not necessarily reflect their in vivo function, given the fact that the ubiquitously existing human beta-glucuronidase could convert the metabolites back to resveratrol locally or systematically in vivo. The present studies have implications for future development of resveratrol and/or its derivatives as a chemotherapeutic agent.

Administration, Oral↗
PubMed2004

Submental intubation in complex craniomaxillofacial trauma.

The submental route for endotracheal intubation is an alternative to nasal intubation or tracheostomy in the surgical management of patients with complex craniomaxillofacial injuries. The critical indication for submental intubation is the requirement for intraoperative maxillomandibular fixation (MMF) in the presence of injuries that preclude nasal intubation and in a situation where a tracheostomy is not otherwise required. MMF to re-establish dental occlusion is essential for a normal functional result in dentate patients with fractures involving alveolar segments of the jaws. However, MMF precludes orotracheal intubation. Nasotracheal intubation is often used but is contraindicated in the presence of skull base fractures and will interfere with the access to certain fracture types. A tracheostomy has a high potential complication rate and in many patients, an alternative to the oral airway is not required beyond the perioperative period. A submental intubation has been used in 11 selected cases amongst 190 consecutively treated patients with craniomaxillofacial trauma over a 3-year period. These cases have been retrospectively reviewed and there have been no significant complications. The indications and technique used are described. Submental intubation is a simple and useful technique with low morbidity in selected cases of craniomaxillofacial trauma and the author's clinical experience with this technique is described.

Adolescent↗
PubMed2003

Induction of G1 cycle arrest in T lymphocytes results in increased extracellular levels of beta-chemokines: a strategy to inhibit R5 HIV-1.

The beta-chemokines RANTES (regulated on activation, normal T cell expressed and secreted), macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta are the natural ligands of the HIV-1 coreceptor CCR5 and compete with the virus for receptor binding. We show that secretion of the beta-chemokines by activated lymphocytes starts before cellular DNA synthesis is detected and demonstrate that transient prolongation of the G(1) phase of the cell cycle by treatment with cytostatic drugs results in increased levels of the three chemokines in culture supernatants. Supernatants collected from peripheral blood mononuclear cells exposed to hydroxyurea, which arrests the cell cycle in late G(1), contained high levels of beta-chemokines. These supernatants were able to inhibit HIV-1 replication when added to cultures of infected lymphocytes. The observed antiviral effect likely was due to the increased levels of beta-chemokines RANTES, MIP-1alpha, and MIP-1beta because (i) supernatants greatly inhibited the replication of HIV-1 BaL, whereas they affected HIV-1 IIIb replication only slightly; (ii) neutralizing antibodies against the chemokines abrogated the antiviral effect of the supernatants; and (iii) the hydroxyurea concentrations shown to up-regulate chemokine levels were not sufficient to inhibit virus replication by depletion of intracellular nucleotide pools. Although antiviral properties have been reported previously for the cytostatic agents shown here to up-regulate beta-chemokine levels, our results provide an additional mechanism by which these drugs may exert antiviral activity. In summary, increased extracellular levels of anti-HIV-1 beta-chemokines resulting from transient prolongation of the G(1) phase of the lymphocyte cell cycle by treatment with cytostatic drugs may help to control the replication of CCR5-using strains of HIV-1.

Cell Cycle↗
PubMed2003

Immune cell function testing: an adjunct to therapeutic drug monitoring in transplant patient management.

Each year, 55 000 organ transplants are performed worldwide. Cumulatively, the number of living organ recipients is now estimated to be over 300 000. Most of these transplant recipients will remain on immunosuppressive drugs for the remainder of their lives to prevent rejection episodes. Controlled doses of these drugs are required to prevent over-medication, which may leave the patient susceptible to opportunistic infection and drug toxicity effects, or under-dosing, which may lead to shortened graft survival because of rejection episodes. This paper describes the result of a multicenter study conducted at the Universities of Pittsburgh, Alabama and Maryland to evaluate an in vitro assay (CylexTM Immune Cell Function Assay) for the measurement of global immune response in transplant patients receiving immunosuppressive therapy. The assay uses a whole blood sample to maintain the presence of the drug during incubation. Following overnight incubation of blood with phytohemagglutinin (PHA), CD4 cells are selected using paramagnetic particles coated with a monoclonal antibody to the CD4 epitope. The CD4-positive cells are targeted as major immunosuppressive drugs are designed to specifically inhibit T-cell activation which has been implicated in rejection. The data generated at these three sites were submitted in support of an Food and Drug Association (FDA) application for the use of this assay in the detection of cell-mediated immunity in an immunosuppressed population. The assay was cleared by the FDA on April 2, 2002. This cross-sectional study was designed to establish ranges for reactivity of this bioassay in the assessment of functional immunity for an individual solid organ recipient at any point in time.

Adult↗
PubMed2003

Spontaneous flexor tendon rupture in the palm: the role of a variation of tendon anatomy.

Spontaneous flexor tendon rupture is rare. We report 2 cases that occurred in association with a common flexor digitorum profundus (FDP) tendon to the ring and small fingers. The tendon bifurcated at the midpalmar level and ruptured at the point of bifurcation. To our knowledge this tendon variation has not been reported previously and has not been associated with spontaneous tendon rupture. Both ruptures occurred in the dominant small finger of elderly men in the absence of trauma. We believe that this unusual tendon arrangement represents a potential weak point in the musculotendinous unit. We discuss the role of this anatomic variant in the pathomechanics of tendon rupture.

Aged↗