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Biomedical subjects

Janet Lee

Publications and source records attributed to Janet Lee.

At least 19 recordsLinked to original sources
PubMed2006

Candidate gene polymorphisms do not differ between newborns with stroke and normal controls.

BACKGROUND AND PURPOSE: Neonatal stroke is increasingly recognized with an estimated incidence of one in 4000 live births per year. Pathways involved in the pathophysiology of neonatal stroke are diverse and may include thrombosis and thrombolysis, vascular reactivity, and inflammation. METHODS: We compared frequencies of polymorphisms in genes regulating thrombosis and thrombolysis, nitric oxide, cytokines, vascular tone, and cell adhesion in a hospital-based cohort of 59 newborns with stroke relative to a random sample of 437 California newborns. RESULTS: Of the 31 polymorphisms evaluated, no variant allele was significantly more common than the reference allele in newborns with stroke than in the general population. CONCLUSIONS: Using a series of polymorphisms in pathways implicated in the etiology of stroke, newborns with stroke were not distinguished from a normal control group. Further studies are needed to determine the interaction of genetic polymorphisms with environmental risk factors in the pathogenesis of neonatal stroke.

Adolescent↗
PubMed2006

A novel form of epithelial wound healing of the embryonic epidermis.

The embryonic epidermis of amniotes is a two-cell layer sheet with a periderm positioned superficial to the basal cell layer which, itself, attaches apically to the basal surface of the periderm and basally to the basal lamina. The presence of the periderm is essential to maintain the basal layer as a two-dimensional monolayer. Wounds to the epidermis that remove selectively just the periderm are healed by a stacking of the basal layer cells that constitute the wound bed. Basal cell stacking involves the desertion of the basal lamina by many of the cells so as to increase their contact area with other basal layer cells. This suggests that a preferential adhesion to the planar basal lamina is not important for the monolayered organization of the basal layer but, instead, association with inner surface of the planar periderm is the principal process that maintains the basal layer as a monolayer. The conversion of the basal layer from monolayer to multilayer during wound healing diminishes its planar area, resulting in movement of the wound borders toward the center of the wound. This is a novel scenario for wound healing.

Actins↗
PubMed2005

Diffusion of single star-branched dendrimer-like DNA.

We report a single-molecule fluorescence study on the diffusion of star-branched polymer dendrimer-like DNA (DL-DNA). The DL-DNA molecules were synthesized from ligating Y-shaped DNA to the fourth generation. It was found through single particle tracking that the diffusion coefficient of DL-DNA changes in a nonmonotonic fashion with its increased concentration possibly due to arm arrest and arm retraction. The diffusion of DL-DNA in linear lambda DNA solution displayed a monotonic concentration dependence 1 order of magnitude greater than the diffusion of DL-DNA in DL-DNA solution. This difference is attributed to the different conformation of DL-DNA and lambda DNA and the entanglement of lambda DNA with a large radius of gyration. Our diffusion study facilitates DL-DNA transportation for drug delivery.

Benzoxazoles↗
PubMed2005

Maternal and infant characteristics associated with perinatal arterial stroke in the infant.

CONTEXT: Perinatal arterial ischemic stroke (PAS) is a common cause of hemiplegic cerebral palsy. Risk factors for this condition have not been clearly defined. OBJECTIVE: To determine maternal and infant characteristics associated with PAS. DESIGN, SETTING, AND PATIENTS: Case-control study nested within the cohort of all 199,176 infants born from 1997 through 2002 in the Kaiser Permanente Medical Care Program, a managed care organization providing care for more than 3 million residents of northern California. Case patients were confirmed by review of brain imaging and medical records (n = 40). Three controls per case were randomly selected from the study population. MAIN OUTCOME MEASURE: Association of maternal and infant complications with risk of PAS. RESULTS: The population prevalence of PAS was 20 per 100,000 live births. The majority (85%) of infants with PAS were delivered at term. The following prepartum and intrapartum factors were more common among case than control infants: primiparity (73% vs 44%, P = .002), fetal heart rate abnormality (46% vs 14%, P<.001), emergency cesarean delivery (35% vs 13%, P = .002), chorioamnionitis (27% vs 11%, P = .03), prolonged rupture of membranes (26% vs 7%, P = .002), prolonged second stage of labor (25% vs 4%, P<.001), vacuum extraction (24% vs 11%, P = .04), cord abnormality (22% vs 6%, P = .01), preeclampsia (19% vs 5%, P = .01), and oligohydramnios (14% vs 3%, P = .01). Risk factors independently associated with PAS on multivariate analysis were history of infertility (odds ratio [OR], 7.5; 95% confidence interval [CI], 1.3-45.0), preeclampsia (OR, 5.3; 95% CI, 1.3-22.0), prolonged rupture of membranes (OR, 3.8; 95% CI, 1.1-12.8), and chorioamnionitis (OR, 3.4; 95% CI, 1.1-10.5). The rate of PAS increased dramatically when multiple risk factors were present. CONCLUSIONS: Perinatal arterial ischemic stroke in infants is associated with several independent maternal risk factors. How these complications, along with their potential effects on the placenta and fetus, may play a role in causing perinatal stroke deserves further study.

Brain↗
PubMed2005

Predictors of outcome in perinatal arterial stroke: a population-based study.

Some infants with perinatal arterial ischemic stroke (PAS) experience development of cerebral palsy (CP), epilepsy, and cognitive impairment, whereas others have a normal outcome. Previous prognostic studies rarely have included all diagnosed cases of PAS within a population. Among 199,176 infants born within Kaiser Permanente from 1997 to 2002, we electronically identified head imaging reports and physician diagnoses suggesting stroke. The diagnosis of PAS was confirmed by review of brain imaging and medical records. Presentation of PAS was considered delayed if symptoms were only noted after 28 days. Outcomes were determined by chart review. Of 40 infants with PAS, 36 were observed over 12 months. Abnormal outcomes included CP (58%), epilepsy (39%), language delay (25%), and behavioral abnormalities (22%). A delayed presentation was associated with increased risk for CP (relative risk [RR], 2.2; 95% confidence interval [CI], 1.2-4.2). Radiological predictors of CP included large stroke size (RR, 2.0; 95% CI, 1.2-3.2) and injury to Broca's area (RR, 2.5; 95% CI, 1.3-5.0), internal capsule (RR, 2.2; 95% CI, 1.1-4.4), Wernicke's area (RR, 2.0; 95% CI, 1.1-3.8), or basal ganglia (RR, 1.9; 95% CI, 1.1-3.3). Among infants with PAS, specific radiological findings and a lack of symptoms in the newborn period are associated with increased risk for CP.

Arterial Occlusive Diseases↗
PubMed2004

Genistein induces G2 arrest in malignant B cells by decreasing IL-10 secretion.

Chronic B cell malignancies are often chemoresistant and the development of new therapeutic modalities is a high priority. Many B cell malignancies have autocrine production of IL-10, which regulates B cell growth and differentiation. Here we demonstrate that the soy isoflavone genistein, a tyrosine kinase inhibitor, rapidly decreased IL-10 secretion followed by upregulation of IFNgamma and inhibition of cell proliferation with pre-dominantly G2 arrest. The antiproliferative effects of genistein were reversed by the addition of exogenous IL-10. Genistein downregulated cdc25C and cdk1 as well as anti-apoptotic proteins survivin and Ian-5. After genistein withdrawal, the G2M arrested cells reentered the cell cycle and underwent apoptosis, which was significantly augmented by fludarabine. We conclude that genistein can sensitize malignant B cells to the action of other chemotherapeutic agents by modulating the cytokine profile and controlling cell cycle progression.

Apoptosis↗
PubMed2004

MMP-2 null mice exhibit an early onset and severe experimental autoimmune encephalomyelitis due to an increase in MMP-9 expression and activity.

Matrix metalloproteinase-2 (MMP-2; gelatinase A) is known to degrade a broad range of extracellular matrix components and chemokines, and has important roles in the processes of cell migration, invasion, and involution during development, as well as during tumor growth and metastasis and in inflammation and repair. To better elucidate the roles of this matrix metalloproteinase in the development and progression of experimental autoimmune encephalomyelitis, we used MMP-2-deficient (KO) mice. Surprisingly, we found that MMP-2 KO mice exhibited an earlier onset and more severe disease than did their wild-type (WT) counterparts. WT mice engrafted with MMP-2 KO bone marrow exhibited a similar earlier onset and more severe clinical disease score than WT mice engrafted with WT bone marrow. Lymphocytes derived from MMP-2 KO mice exhibited increased transmigration through endothelial cell monolayers as well as through collagen type IV and laminin-coated BD BIOCOAT inserts, which correlated with a 3-fold increase in expression of MMP-9 and was abrogated by inhibition of MMP activity. We demonstrated a correlation between expression levels of MMP-9 and MT1-MMP expression and suggest a signaling pathway involving tethering of MMP-2 to MT1-MMP as a modulator of MMP-9 expression. Last, we discuss other possible MMP-2-mediated mechanisms which may contribute to the observed phenotype.

Age of Onset↗
PubMed2004

Effect of vitamin A depletion on nonvisual phototransduction pathways in cryptochromeless mice.

Mice exhibit multiple nonvisual responses to light, including 1) photoentrainment of circadian rhythm; 2) "masking," which refers to the acute effect of light on behavior, either negative (activity suppressing) or positive (activity inducing); and 3) pupillary constriction. In mammals, the eye is the sole photosensory organ for these responses, and it contains only 2 known classes of pigments: opsins and cryptochromes. No individual opsin or cryptochrome gene is essential for circadian photoreception, gene photoinduction, or masking. Previously, the authors found that mice lacking retinol-binding protein, in which dietary depletion of ocular retinaldehyde can be achieved, had normal light signaling to the SCN, as determined by per gene photoinduction. In the present study, the authors analyzed phototransduction to the SCN in vitamin A-replete and vitamin A-depleted rbp-/- and rbp-/-cry1-/-cry2-/- mice using molecular and behavioral end points. They found that vitamin A-depleted rbp-/- mice exhibit either normal photoentrainment or become diurnal. In contrast, while vitamin A-replete rbp-/-cry1-/-cry2-/- mice are light responsive (with reduced sensitivity), vitamin A-depleted rbp-/-cry1-/-cry2-/- mice, which presumably lack functional opsins and cryptochromes, lose most behavioral and molecular responses to light. These data demonstrate that both cryptochromes and opsins regulate nonvisual photoresponses.

Animals↗
PubMed2003

Intraventricular neurocytomas.

The literature to date on the treatment of CNC reflects an evolution of clinical practice in neurooncology. The advent of sophisticated tools, such as MRS and molecular pathology, has facilitated more efficient diagnosis of CNC. Decreased morbidity associated with surgical intervention has resulted in better outcomes in patients undergoing resection of CNC. Prospective monitoring of treated patients with MRI coupled with judicious use of radiosurgery will likely further decrease treatment-related morbidity.

Brain↗
PubMed2003

A phase I study of paclitaxel, estramustine phosphate and vinorelbine (Pacl-E-Vin) in advanced malignancies: triple tubulin targeting.

Anti-tubulin couplets have activity in hormone-resistant prostate cancer. This study was designed to define the dose-limiting toxicity (DLT) and recommended phase II dose (RPTD) of the unique triplet combination of paclitaxel, estramustine phosphate (EMP) and vinorelbine (Pacl-E-Vin). Patients with advanced malignancies who had failed standard therapy, ECOG performance status (PS 0-2) and adequate organ function were included. Dose of EMP was fixed at 300 mg/m2/dose p.o. t.i.d. on days 1-3 and 8-10. Vinorelbine dose was 20 mg/m2/day i.v. on days 3 and 10. Paclitaxel was dose escalated from 40 to 50 mg/m /day i.v. on days 3 and 10. Cycles were repeated every 3 weeks. Twelve adults (median age 72) were entered on this study. Primary tumors included prostate (n=7), cervix (n=2), melanoma (n=1), colon (1) and lung with synchronous prostate cancer (n=1). Nine patients had received no prior chemotherapy, one had received a prior regimen and two had received two or more prior regimens. Of four evaluable patients at dose level 1, one patient had grade 3 neutropenia leading to the day 10 dose being withheld. Of five evaluable patients at dose level 2, there was one DLT (febrile neutropenia) and two grade 3 neutropenias leading to the day 10 dose being withheld. One patient had a lower extremity deep vein thrombosis. Other side effects were mild and reversible. Nine patients were evaluable for efficacy: three with prostate cancer had a greater than 50% prostate-specific antigen (PSA) response, and a patient with synchronous prostate and lung cancer had a greater than 50% PSA response. We conclude that the DLT of Pacl-E-Vin is neutropenia. RPTD is vinorelbine 20 mg/m2, paclitaxel 40 mg/m2, both administered on days 3 and 10, and EMP 900 mg/m2/day on days 1-3 and 8-10, q3w. Dose omission at day 10 followed by 20% dose reduction of paclitaxel and vinorelbine is recommended in the event of grade 3 neutropenia. Activity in hormone-refractory prostate cancer is promising and warrants phase II evaluation.

Adult↗
PubMed2003

Phase I study of amifostine as a cytoprotector of the gemcitabine/cisplatin combination in patients with advanced solid malignancies.

Our objective was to evaluate the role of amifostine as a cytoprotector in patients with solid tumors receiving the myelosuppressive regimen of gemcitabine/cisplatin combination. Patients with advanced solid tumors were randomized to gemcitabine-amifostine-cisplatin (GAP) or gemcitabine-cisplatin (GP) in Cycle 1 (C1) and then were crossed over to the other treatment in Cycle 2 (C2). Amifostine at 740 mg/m2, followed by gemcitabine and cisplatin, were given for 2 consecutive weeks, every 4 weeks. Two GP combinations were studied: G 1000 mg/m2 and P 40 mg/m2 days 1, 8 (high dose), and G 800 mg/m2 and P 30 mg/m2 days 1, 8 (low dose). Forty patients were enrolled. Of the 19 patients treated with high-dose GP, 11 (nine patients GP in C1 and GAP in C2, two patients GAP in C1 and GP in C2) completed 2 cycles of therapy. Of the eight non-evaluable patients, five patients dropped out due to toxicity or refusal after treatment with amifostine in C1. Of the 21 patients treated with low-dose GP, 15 (eight patients GP in C1 and GAP in C2, seven patients GAP in C1 and GP in C2) were likewise evaluable. The incidence of grade 3 or 4 hematologic toxicities was similar for GP and GAP during the first 2 cycles of treatment, and there were no statistically significant differences in mean absolute neutrophil count, hemoglobin level and platelet levels between the cycles in each arm. We conclude that amifostine, at 740 mg/m2, does not lead to less myelosuppression when combined with gemcitabine/cisplatin chemotherapy regimens and may possibly contribute to subjective intolerance.

Adult↗
PubMed2003

Benefits and risks of solitary islet transplantation for type 1 diabetes using steroid-sparing immunosuppression: the National Institutes of Health experience.

OBJECTIVE: The aim of this study was to describe the National Institutes of Health's experience initiating an islet isolation and transplantation center, including descriptions of our first six recipients, and lessons learned. RESEARCH DESIGN AND METHODS: Six females with chronic type 1 diabetes, hypoglycemia unawareness, and no endogenous insulin secretion (undetectable serum C-peptide) were transplanted with allogenic islets procured from brain dead donors. To prevent islet rejection, patients received daclizumab, sirolimus, and tacrolimus. RESULTS: All patients noted less frequent and less severe hypoglycemia, and one-half were insulin independent at 1 year. Serum C-peptide persists in all but one patient (follow-up 17-22 months), indicating continued islet function. Two major procedure-related complications occurred: partial portal vein thrombosis and intra-abdominal hemorrhage. While we observed no cytomegalovirus infection or malignancy, recipients frequently developed transient mouth ulcers, diarrhea, edema, hypercholesterolemia, weight loss, myelosuppression, and other symptoms. Three patients discontinued immunosuppressive therapy: two because of intolerable toxicity (deteriorating kidney function and sirolimus-induced pneumonitis) while having evidence for continued islet function (one was insulin independent) and one because of gradually disappearing islet function. CONCLUSIONS: We established an islet isolation and transplantation program and achieved a 50% insulin-independence rate after at most two islet infusions. Our experience demonstrates that centers not previously engaged in islet transplantation can initiate a program, and our data and literature analysis support not only the promise of islet transplantation but also its remaining hurdles, which include the limited islet supply, procedure-associated complications, imperfect immunosuppressive regimens, suboptimal glycemia control, and loss of function over time.

Adult↗
PubMed2002

Drosophila atrophin homolog functions as a transcriptional corepressor in multiple developmental processes.

Dentatorubral-pallidoluysian atrophy is a progressive neurodegenerative disease caused by the expansion of a polyglutamine repeats within the Atrophin-1 protein. The in vivo function of Atrophin-1 is unknown. We have characterized a Drosophila gene encoding an Atrophin family protein. Analysis of mutant phenotypes indicates that Drosophila Atrophin is required in diverse developmental processes including early embryonic patterning. Drosophila Atrophin genetically interacts with the transcription repressor even-skipped and is required for its repressive function in vivo. Drosophila Atrophin directly binds to Even-skipped in vitro. Furthermore, both human Atrophin-1 and Drosophila Atrophin repress transcription in vivo when tethered to DNA, and poly-Q expansion in Atrophin-1 reduces this repressive activity. We propose that Atrophin proteins function as versatile transcriptional corepressors and discuss a model that deregulation of transcription may contribute to the pathogenesis of neurodegeneration.

Animals↗
PubMed2002

Antiandrogen blocks estrogen-induced masculinization of the song system in female zebra finches.

Song behavior and the neural song system that serves it are sexually dimorphic in zebra finches. In this species, males sing and females normally do not. The sex differences in the song system include sex differences in the proportion of neurons that express androgen receptors, which is higher in specific brain regions of males. Estradiol (E2) administered in early development profoundly masculinizes the song system of females, including the proportion of neurons expressing androgen receptors. We examined whether or not the expression of these androgen receptors was causally related to the E2-induced masculinization of this system by co-administering Flutamide, which blocks androgen action at the receptor, along with E2 at hatching. E2 alone had its usual masculinizing effect on the female song system, measured in adulthood: increasing the size of song nuclei, the size of neurons in HVC, RA, and 1MAN, and the number of neurons in HVC. E2's masculinizing action, however, was significantly diminished on all measures by co-administering Flutamide. Indeed, females receiving both E2 and Flutamide were never significantly more masculine than controls on any measure. Flutamide alone had no effect. Our results strongly suggest that the activation of androgen receptors is necessary for the E2-induced masculinization of the song system in females.

Androgen Antagonists↗