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Biomedical subjects

P P Lee

Publications and source records attributed to P P Lee.

At least 19 recordsLinked to original sources
PubMed2004

A prospective study of Type 2 diabetes and depressive symptoms in the elderly: the Rancho Bernardo Study.

AIMS: The association between Type 2 diabetes and depressive symptoms was examined prospectively to assess possible causal relationships between the two diseases. METHODS: A cohort of 971 men and women aged 50 and older from the adult population of Rancho Bernardo, California had an oral glucose tolerance test and completed the Beck Depression Inventory (BDI) at two clinic visits, 1984-87 and 1992-96. RESULTS: Depressive symptoms at baseline were associated with higher follow-up levels of non-fasting plasma glucose (P = 0.001) and an increased risk of developing Type 2 diabetes [odds ratio (OR) = 2.50; 95% confidence interval (CI) = 1.29-4.87], independent of sex, age, exercise and body mass index. Conversely, baseline non-fasting plasma glucose was not significantly associated with follow-up depressive symptoms and Type 2 diabetes at baseline was not significantly associated with the onset of BDI scores > or = 11 by the second visit (OR = 0.73; 95% CI = 0.41-1.30). CONCLUSIONS: Depressed mood is more likely to be a risk factor for Type 2 diabetes in older adults than the reverse.

Age Distribution↗
PubMed2001

A comparison of two types of dendritic cell as adjuvants for the induction of melanoma-specific T-cell responses in humans following intranodal injection.

Dendritic cells (DCs) elicit potent anti-tumoral T-cell responses in vitro and in vivo. However, different types of DC have yet to be compared for their capacity to induce anti-tumor responses in vivo at different developmental stages. Herein, we correlated the efficiencies of different types of monocyte-derived DC as vaccines on the resulting anti-tumor immune responses in vivo. Immature and mature DCs were separately pulsed with a peptide derived from tyrosinase, MelanA/MART-1 or MAGE-1 and a recall antigen. Both DC populations were injected every 2 weeks in different lymph nodes of the same patient. Immune responses were monitored before, during and after vaccination. Mature DCs induced increased recall antigen-specific CD4(+) T-cell responses in 7/8 patients, while immature DCs did so in only 3/8. Expansion of peptide-specific IFN-gamma-producing CD8(+) T cells was observed in 5/7 patients vaccinated with mature DCs but in only 1/7 using immature DCs. However, these functional data did not correlate with the tetramer staining. Herein, immature DCs also showed expansion of peptide-specific T cells. In 2/4 patients vaccinated with mature DCs, we observed induction of peptide-specific cytotoxic T cells, as monitored by chromium-release assays, whereas immature DCs failed to induce peptide-specific cytotoxic T cells in the same patients. Instead, FCS-cultured immature DCs induced FCS-specific IgE responses in 1 patient. Our data demonstrate that this novel vaccination protocol is an efficient approach to compare different immunization strategies within the same patient. Thus, our data define FCS-free cultured mature DCs as superior inducers of T-cell responses in melanoma patients.

Adjuvants, Immunologic↗
PubMed2001

DNA hypomethylation perturbs the function and survival of CNS neurons in postnatal animals.

DNA methyltransferase I (Dnmt1), the maintenance enzyme for DNA cytosine methylation, is expressed at high levels in the CNS during embryogenesis and after birth. Because embryos deficient for Dnmt1 die at gastrulation, the role of Dnmt1 in the development and function of the nervous system could not be studied by using this mutation. We therefore used the cre/loxP system to produce conditional mutants that lack Dnmt1 in neuroblasts of embryonic day 12 embryos or in postmitotic neurons of the postnatal animal. Conditional deletion of the Dnmt1 gene resulted in rapid depletion of Dnmt1 proteins, indicating that the enzyme in postmitotic neurons turns over quickly. Dnmt1 deficiency in postmitotic neurons neither affected levels of global DNA methylation nor influenced cell survival during postnatal life. In contrast, Dnmt1 deficiency in mitotic CNS precursor cells resulted in DNA hypomethylation in daughter cells. Whereas mutant embryos carrying 95% hypomethylated cells in the brain died immediately after birth because of respiratory distress, mosaic animals with 30% hypomethylated CNS cells were viable into adulthood. However, these mutant cells were eliminated quickly from the brain within 3 weeks of postnatal life. Thus, hypomethylated CNS neurons were impaired functionally and were selected against at postnatal stages.

Animals↗
PubMed2001

Development of the 25-item National Eye Institute Visual Function Questionnaire.

OBJECTIVE: To develop and test the psychometric properties of a 25-item version of the National Eye Institute Visual Function Questionnaire (NEI VFQ-25). DESIGN: Prospective observational cohort study of persons with 1 of 5 chronic eye diseases or low vision who were scheduled for nonurgent visits in ophthalmology practices and a reference sample of persons without eye disease. SETTING: Eleven university-based ophthalmology practices and the NEI Clinical Center. PATIENTS: Eligible participants had to have 1 of the following eye conditions: age-related cataracts, age-related macular degeneration, diabetic retinopathy, primary open-angle glaucoma, cytomegalovirus retinitis, or low vision from any cause. Seven of the 12 sites also enrolled persons in a reference sample. Reference sample participants had no evidence of underlying eye disease but were scheduled for either screening eye examinations or correction of refractive error. All eligible persons had to be 21 years or older, English speaking, and cognitively able to give informed consent and participate in a health status interview. MEASUREMENTS AND MAIN RESULTS: To provide the data needed to create the NEI VFQ-25, all subjects completed an interview that included the 51-item NEI VFQ. Estimates of internal consistency indicate that the subscales of the NEI VFQ-25 are reliable. The validity of the NEI VFQ-25 is supported by high correlations between the short- and long-form versions of the measure, observed between-group differences in scores for persons with different eye diseases of varying severity, and the moderate-to-high correlations between the NEI VFQ-25 subscales that have the most to do with central vision and measured visual acuity. CONCLUSIONS: The reliability and validity of the NEI VFQ-25 are comparable to those of the 51-item NEI VFQ field test version of the survey. This shorter version will be more feasible in settings such as clinical trials where interview length is a critical consideration. In addition, preliminary analyses indicate that the psychometric properties of the NEI VFQ-25 are robust for the eye conditions studied; this suggests that the measure will provide reproducible and valid data when used across multiple conditions of varying severity.

Chronic Disease↗
PubMed2001

Functional role of matrix metalloproteinases (MMPs) in mammary epithelial cell development.

The extracellular matrix (ECM) is an important regulator of mammary epithelial cell (MEC) function and is remodeled by matrix metalloproteinases (MMPs). To investigate the significance and regulation of MMP activity in normal MEC, we utilized a primary culture model in which rat MEC were grown three dimensionally within a reconstituted basement membrane (RBM) in defined serum-free medium. Zymograms of culture medium demonstrated that five major gelatinases of 97, 80, 74, 69, and 65 kDa were secreted by MEC and were distinct from gelatinases of RBM origin. Based on molecular weight, p-aminophenylmercuric acid activation, immunoblotting with MMP-specific antibodies, inhibition by EDTA, a peptide containing the prodomain sequence of MMP (TMRKPRCGNPDVAN) and two synthetic MMP inhibitors (BB-94 and CGS 27023A), these were classified as inactive and active forms of MMP-9 and MMP-2. The maximal MMP activities occurred when MEC were in a rapid proliferation and branching phase and declined after they underwent functional differentiation. Known regulators of MEC growth and differentiation were evaluated for their ability to modulate gelatinase activity in primary culture. Secretion of one or both MMPs was inhibited by EGF, TGFalpha, prolactin, and hydrocortisone and stimulated by progesterone. Furthermore, the functional significance of MMPs was demonstrated since three MMP inhibitors blocked branching morphogenesis elicited by the absence of hydrocortisone. Additionally, two synthetic MMP inhibitors not only inhibited epithelial cell growth but also inhibited normal alveolar development of the MEC. Finally, these drugs were found to enhance MMP secretion from MEC, although the activity of the secreted MMPs was inhibited as long as the drug was present.

Animals↗
PubMed2001

A critical role for Dnmt1 and DNA methylation in T cell development, function, and survival.

The role of DNA methylation and of the maintenance DNA methyltransferase Dnmt1 in the epigenetic regulation of developmental stage- and cell lineage-specific gene expression in vivo is uncertain. This is addressed here through the generation of mice in which Dnmt1 was inactivated by Cre/loxP-mediated deletion at sequential stages of T cell development. Deletion of Dnmt1 in early double-negative thymocytes led to impaired survival of TCRalphabeta(+) cells and the generation of atypical CD8(+)TCRgammadelta(+) cells. Deletion of Dnmt1 in double-positive thymocytes impaired activation-induced proliferation but differentially enhanced cytokine mRNA expression by naive peripheral T cells. We conclude that Dnmt1 and DNA methylation are required for the proper expression of certain genes that define fate and determine function in T cells.

Animals↗
PubMed2001

Melatonin and its analogs potentiate the nifedipine-sensitive high-voltage-activated calcium current in the chick embryonic heart cells.

Effects of melatonin and its analogs on the voltage-activated calcium current of embryonic chick ventricular cardiomyocytes were investigated. Myocytes were dissociated from 14- to 16-day-old chicks (yellow Red Rob) embryonic hearts and cultured for 2 3 days. Calcium currents were studied by the patch-clamp technique. Whole-cell current recording showed nifedipine-sensitive, high-voltage-activated L-type calcium current inactivated in 70-100 ms during the voltage step period of 200 ms. There was no evidence of low-voltage-activated T-type calcium channels. Melatonin (ejected solution: 50 micromol/L melatonin; concentration at the vicinity of recording cell: about 1-5 micromol/L melatonin) and its analogs, 2-iodomelatonin and 2-iodo-n-butanol-5-methoxytryptamine, significantly increased the amplitude of the calcium current by 42-62%. The effect of melatonin on the L-type calcium current was not desensitised by repeated melatonin treatment. Our results suggest a specific melatonin receptor-mediated action on the calcium channel of the embryonic chick myocyte. The melatonin-induced increase in high-voltage calcium current may increase myocyte contractility and enhance cardiac output. A regulatory role of melatonin on the chick cardiac function should be further considered.

Animals↗
PubMed2001

Inactivation of Notch 1 in immature thymocytes does not perturb CD4 or CD8T cell development.

Notch proteins influence cell-fate decisions in many developing systems. Several gain-of-function studies have suggested a critical role for Notch 1 signaling in CD4-CD8 lineage commitment, maturation and survival in the thymus. However, we show here that tissue-specific inactivation of the gene encoding Notch 1 in immature (CD25+CD44-)T cell precursors does not affect subsequent thymocyte development. Neither steady-state numbers nor the rate of production of CD4+ and CD8+ mature thymocytes is perturbed in the absence of Notch 1. In addition, Notch 1-deficient thymocytes are normally sensitive to spontaneous or glucocorticoid-induced apoptosis. In contrast to earlier reports, these data formally exclude an essential role for Notch 1 in CD4-CD8 lineage commitment, maturation or survival.

Animals↗
PubMed2001

Double-blind, placebo-controlled study of single-dose amphetamine formulations in ADHD.

OBJECTIVE: To compare the efficacy and time course of single morning doses of Adderall, extended-release, and immediate-release dextroamphetamine sulfate. METHOD: Thirty-five children with attention-deficit/hyperactivity disorder, combined type, were given Adderall, immediate-release dextroamphetamine, dextroamphetamine Spansules, and placebo in a randomized, double-blind, crossover study. Behavior ratings, locomotor activity measurements, and academic measures were obtained over a period of 8 weeks. RESULTS: All three drugs exhibited robust efficacy versus placebo on nearly all measures. The effects of dextroamphetamine Spansules were less robust in the morning, particularly compared with Adderall, but they lasted 3 to 6 hours longer, depending on the measure. Although parent behavior ratings and locomotor activity showed improvements up to 12 hours after single doses of all three drugs, the number of math problems attempted and completed correctly 4 hours after dosing were only robustly increased by Spansules. CONCLUSIONS: Both immediate-release amphetamines demonstrated earlier onset of effects, but dextroamphetamine Spansules showed more sustained effects that were present on a wider range of measures.

Amphetamines↗
PubMed2001

Regulation of milk protein gene expression in normal mammary epithelial cells by tumor necrosis factor.

Tumor necrosis factor-alpha (TNF) is a physiologically significant regulator of mammary gland development, stimulating growth and branching morphogenesis of mammary epithelial cells (MEC) and modulating functional differentiation. The present studies were performed to determine the mechanism by which TNF modulated functional differentiation. In rat MEC in primary culture, TNF inhibited accumulation of whey acidic protein and beta-casein messenger RNAs in a time- and concentration-dependent manner. In contrast, levels of transferrin messenger RNA, the product of another milk protein gene, were not inhibited by TNF, suggesting selectivity. Using a nuclear run-on assay in the immortalized HC11 mammary epithelial cell line and the transcriptional inhibitor actinomycin D in MEC in primary culture, the effects of TNF were shown to be mediated by both a decrease in transcription and a decrease in the stability of the whey acidic protein and beta-casein transcripts. Additionally, TNF stimulated the binding of nuclear factor-kappaB to a consensus kappaB-oligonucleotide, increased the stability of matrix metalloproteinase-9 (MMP-9) transcripts, and increased MMP-9 activity. Together, these data suggest that TNF may exert its effects on milk protein gene expression either directly via nuclear factor-kappaB modulation of transcription, or indirectly via MMP-9-induced remodeling of the architectural or hormonal environment surrounding the MEC.

Animals↗
PubMed2000

Melanocyte destruction after antigen-specific immunotherapy of melanoma: direct evidence of t cell-mediated vitiligo.

Current strategies for the immunotherapy of melanoma include augmentation of the immune response to tumor antigens represented by melanosomal proteins such as tyrosinase, gp100, and MART-1. The possibility that intentional targeting of tumor antigens representing normal proteins can result in autoimmune toxicity has been postulated but never demonstrated previously in humans. In this study, we describe a patient with metastatic melanoma who developed inflammatory lesions circumscribing pigmented areas of skin after an infusion of MART-1-specific CD8(+) T cell clones. Analysis of the infiltrating lymphocytes in skin and tumor biopsies using T cell-specific peptide-major histocompatibility complex tetramers demonstrated a localized predominance of MART-1-specific CD8(+) T cells (>28% of all CD8 T cells) that was identical to the infused clones (as confirmed by sequencing of the complementarity-determining region 3). In contrast to skin biopsies obtained from the patient before T cell infusion, postinfusion biopsies demonstrated loss of MART-1 expression, evidence of melanocyte damage, and the complete absence of melanocytes in affected regions of the skin. This study provides, for the first time, direct evidence in humans that antigen-specific immunotherapy can target not only antigen-positive tumor cells in vivo but also normal tissues expressing the shared tumor antigen.

Antigens, Neoplasm↗
PubMed2000

The use of HLA A2.1/p53 peptide tetramers to visualize the impact of self tolerance on the TCR repertoire.

p53 is an attractive target for cancer immunotherapy since it is overexpressed in half of all tumors. However, it is also expressed in normal lymphoid tissue, and self tolerance leaves a p53-specific repertoire purged of high avidity CTL. To better understand the mechanism of tolerance and the basis for such low avidity interaction, p53-specific CTL from p53 deficient (p53-) and sufficient (p53+) A2.1/Kb transgenic mice were compared with respect to their ability to bind HLA-A2.1 tetramers containing cognate murine p53 peptide Ag, p53 261-269. Since the murine CD8 molecule cannot interact with human HLA-A2.1, this tests the ability of the TCR to bind the A2.1/peptide complex tetramer. CTL from p53- mice demonstrated strong binding of such A2.1/p53 261-269 tetramers; however, the CTL from tolerant p53+ mice were devoid of tetramer-binding CD8+ T cells. Examination of TCR expression at the clonal level revealed that CTL from p53+ and p53- mice each expressed comparable levels of the p53-specific TCR. These results indicate that normal expression of p53 promotes elimination of T cells expressing TCRs with sufficient affinity to achieve stable binding of the A2.1/p53 261-269 tetramers.

Amino Acid Sequence↗
PubMed2000

Mammary fibroblasts stimulate growth, alveolar morphogenesis, and functional differentiation of normal rat mammary epithelial cells.

Stromal-epithelial interactions play a profound role in regulating normal and tumor development in the mammary gland. The molecular details of these events, however, are incompletely understood. A novel serum-free transwell coculture system was developed to study the natural paracrine interactions between mammary epithelial cells (MEC) and mammary fibroblasts (MFC) isolated from normal rats during puberty. The MEC were cultured within a reconstituted basement membrane (RBM) in transwell inserts with or without MFC in the lower well. The presence of MFC stimulated epithelial cell growth, induced alveolar morphogenesis, and enhanced casein accumulation, a marker of the functional differentiation of MEC, but did not induce ductal morphogenesis. Potent mitogenic, morphogenic, and lactogenic effects were observed when the MFC were cultured either on plastic or within a layer of RBM. Although most MFC maintained on plastic died after 1 wk in serum-free medium, fibroblast survival was enhanced significantly when the MFC were cultured within the RBM. Taken together, this in vitro model effectively reconstitutes a physiologically relevant three-dimensional microenvironment for MEC and MFC, and seems ideal for studying the locally derived factors that regulate the developmental fate of the epithelial and fibroblast compartments of the mammary gland.

Animals↗
PubMed2000

TGFbeta1 stimulates the secretion of matrix metalloproteinase 2 (MMP2) and the invasive behavior in human ovarian cancer cells, which is suppressed by MMP inhibitor BB3103.

The present study investigated the modulatory role of transforming growth factor beta 1 (TGFbeta1) on the secretion of matrix metalloproteinases (MMPs) and tested whether the altered secretion of MMPs could directly affect the invasive behavior of ovarian cancer cells. To this aim, human ovarian cancer SKOV3 cells were treated once with vehicle or various concentrations of TGFbeta1 for 24 h. Gelatinase activities in conditioned media were analyzed by zymography and densitometry. TGFbeta1 dose-dependently stimulated the secretion of a 68-kDa gelatinase, which was characterized as an MMP because its activity was inhibited by a metalloproteinase inhibitor 1,10-phenanthroline, and by a synthetic MMP inhibitor BB3103. In addition, we used aminophenylmercuric acetate (APMA) to activate latent gelatinases. APMA time-dependently decreased the activity of 68-kDa gelatinase, and increased the activities of 64- and 62-kDa gelatinolytic bands. The 68-kDa gelatinase was further characterized as MMP2 (gelatinase A) by immunoblotting analysis. We then tested TGFbeta1 effect on the invasive potential of SKOV3 cells as assessed by the migration ability through reconstituted basement membrane, and further investigated whether TGFbeta1 may act through modulating the MMP activity to affect ovarian cancer cell invasion. The results show that TGFbeta1 stimulated the invasive behavior of SKOV3 cells, and that MMP inhibitor BB3103 abrogated this effect of TGFbeta1. In conclusion, this study indicates that TGFbeta1 may act partly through stimulating the secretion of MMP in promoting the invasive behavior of human ovarian cancer cells. Furthermore, this work supports the idea that specific MMP inhibitors of the hydroxamate class could be therapeutically useful in controlling cancer cell invasion/metastasis.

Blotting, Western↗
PubMed2000

Evidence that specific T lymphocytes may participate in the elimination of chronic myelogenous leukemia.

Although the immune system has long been implicated in the control of cancer, evidence for specific and efficacious immune responses in human cancer has been lacking. In the case of chronic myelogenous leukemia (CML), either allogeneic bone marrow transplant (BMT) or interferon-alpha2b (IFN-alpha2b) therapy can result in complete remission, but the mechanism for prolonged disease control is unknown and may involve immune anti-leukemic responses. We previously demonstrated that PR1, a peptide derived from proteinase 3, is a potential target for CML-specific T cells. Here we studied 38 CML patients treated with allogeneic BMT, IFN- alpha2b or chemotherapy to look for PR1-specific T cells using PR1/HLA-A*0201 tetrameric complexes. There was a strong correlation between the presence of PR1-specific T cells and clinical responses after IFN-alpha and allogeneic BMT. This provides for the first time direct evidence of a role for T-cell immunity in clearing malignant cells.

Blood Circulation↗
PubMed2000

Functional significance of MMP-9 in tumor necrosis factor-induced proliferation and branching morphogenesis of mammary epithelial cells.

Tissue remodeling is a key process involved in normal mammary gland development, with matrix metalloproteinases (MMPs) playing an important role in this process. Our laboratory has demonstrated that tumor necrosis factor (TNF) stimulates branching morphogenesis of mammary epithelial cells (MEC) within a reconstituted basement membrane. Studies were therefore undertaken to determine whether MMPs might mediate the effects of TNF. Using a primary culture model in which rat MEC grow three-dimensionally within a reconstituted basement membrane, we found that TNF stimulated secretion of MMP-9 but not MMP-2. To determine whether MMP-9 was involved in TNF-induced proliferation and branching morphogenesis, we used a peptide containing the prodomain sequence of MMPs and two MMP inhibitors. Both the prodomain peptide (5 x 10(-4)-10(-3) M), as well as BB-94 (10(-8)-10(-5) M) and CGS 27023A (10(-6)-10(-5) M), inhibited TNF-induced proliferation and branching morphogenesis in a concentration-dependent manner. Finally, to verify the specific requirement for MMP-9, we demonstrated that an MMP-9 neutralizing antibody blocked TNF-induced proliferation and branching morphogenesis. Together, these data suggest that TNF-regulated MMP-9 may play a role in the controlled invasion of the fad pad that occurs during normal mammary gland development and that misregulation of MMP-9 may contribute to the invasiveness of breast cancer.

Animals↗