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Biomedical subjects

Fred Lee

Publications and source records attributed to Fred Lee.

15 recordsLinked to original sources
PubMed2006

Focal prostate cryoablation: initial results show cancer control and potency preservation.

BACKGROUND: Focal prostate cryoablation is the less-than-complete ablation of the gland with ice. Known tumor is ablated aggressively, whereas contralateral prostate tissue and surrounding structures are spared. This method offers targeted local cancer control aiming at sexual potency and urinary continence preservation in patients whose prostate cancer is believed to be unilateral. PATIENTS AND METHODS: Patients who had a strong desire for preservation of sexual function and continence were informed of focal prostate cryoablation as an investigational treatment option for clinically organ-confined, unilateral tumor identified by color Doppler ultrasonography and confirmed by targeted and systematic biopsy. Only stage, not preoperative serum prostate specific antigen concentration (PSA) or tumor differentiation, was considered a potential contraindication. Thirty-one men with a mean age of 63 years underwent the procedure. Follow-up consisted of PSA measurement every 3 months for 1 year and every 6 months thereafter, with biopsies at 6 months and 1, 2, and 5 years and following any three consecutive PSA rises. Potency was determined with a patient questionnaire filled in without the physician present. RESULTS: At a mean follow-up of 70 months, biochemical disease-free status, according to the ASTRO definition, was maintained by 92.8% of patients (26/28) and a 96.0% negative-biopsy rate (24/25) was observed. The one biopsy-positive patient was subsequently treated with full-gland cryoablation and remains disease free. Potency was maintained by 48.1% of patients (13/27) and another 40.7% (11/27) were potent with oral pharmaceutical assistance, yielding a total potency-preservation rate of 88.9%. No complications were observed. CONCLUSION: Focal cryoablation can provide biochemical and local control of prostate cancer while preserving potency and continence. Further investigation is needed.

Aged↗
PubMed2005

Bioengineering lactic acid bacteria to secrete the HIV-1 virucide cyanovirin.

An urgent need exists to prevent the sexual transmission of HIV-1. With prevalence rates exceeding 35% in parts of sub-Saharan Africa, increasing attention has been placed on developing and testing microbicidal agents capable of preventing virus transmission at mucosal sites. HIV-1 microbicides must meet several requirements before their widespread use. The drugs must be able to neutralize a diversity of HIV-1 strains, not induce mucosal inflammation, be associated with minimal side effects, and be effective for a prolonged period after a single application. Recent work has demonstrated the utility of recombinant lactic acid bacteria (LAB) as agents of mucosal drug delivery. Here, we describe the bioengineering of strains of LAB to secrete the prototypic virucidal compound cyanovirin (CV-N) and demonstrate the anti-HIV-1 activity of secreted CV-N. Our results suggest that recombinant LAB may serve as effective microbicidal compounds and deserve in vivo testing in simian immunodeficiency virus models of mucosal virus transmission.

Bacterial Proteins↗
PubMed2005

Microwave ablation of hepatic tumors using dual-loop probes: results of a phase I clinical trial.

Hepatic tumors are a common cause of death worldwide. However, few patients are candidates for resection at the time of presentation. Microwave ablation is a viable alternative available for these patients. To date, only straight antennas are used for microwave ablation. Recently, a prototype loop-shaped microwave antenna was developed that, in animal studies, more effectively kills tumors. For this study, the dual-probe lesions were created by placing the probes in both tumors and normal livers. Lesions were created with 60 watts applied power for 5-7 minutes. The livers were sectioned and stained for viability. The average ablation volume was 63.9 +/- 8.7 cm(3). Microwave ablation with the loop probes results in complete tumor kill at the ablation/tumor interface, and adjacent to surrounding blood vessels. In addition, vessels within the ablation/tumor interface failed to show viable cells. The shape of the lesions was not distorted by proximity to blood vessels. The advantages of this configuration over conventional straight probes include the ability to encircle a tumor, deliver large amounts of precisely targeted microwave energy to the tumor, and spare normal liver outside the loop.

Equipment Design↗
PubMed2004

Enhanced gene silencing of HIV-1 specific siRNA using microRNA designed hairpins.

Post-transcriptional inhibition of HIV-1 replication can be achieved by RNA interference (RNAi). The cellular expression of short interfering RNA (siRNA) or short hairpin RNA (shRNA) homologous to regions of the HIV-1 genome decreases viral replication by the selective degradation of targeted RNA. Here, we demonstrate that another class of noncoding regulatory RNA, termed microRNA (miRNA), can be used to deliver antiviral RNAi. By incorporating sequences encoding siRNA targeting the HIV-1 transactivator protein tat into a human miR-30 pre-microRNA (pre-miRNA) backbone, we were able to express tat siRNA in cells. The tat siRNA delivered as pre-miRNA precursor was 80% more effective in reducing HIV-1 p24 antigen production than tat siRNA expressed as conventional shRNA. Our results confirm the utility of expressing HIV-1 specific siRNA through a miR-30 precursor stem-loop structure and suggest that this strategy can be used to increase the antiviral potency of RNAi.

Base Sequence↗
PubMed2004

Efficient gene transfer of HIV-1-specific short hairpin RNA into human lymphocytic cells using recombinant adeno-associated virus vectors.

The cellular introduction of short, interfering RNA leads to sequence-specific degradation of homologous mRNA, a process termed RNA interference (RNAi). Here, we report that recombinant adeno-associated virus 2 (rAAV-2) can be used to transfer short hairpin (sh) RNA expression cassettes genetically into human cells. HIV-1 replication was suppressed by >95% in H9 cells and primary human lymphocytes that expressed shRNA targeting the first exon of the viral transactivator protein tat compared to control cells. rAAV-2 integrated stably into the host genome, leading to long-term expression of tat shRNA. Our findings demonstrate the utility of rAAV-2 for the genetic transfer of shRNA expression cassettes into human cells, providing an alternative to using retroviral vectors as RNAi delivery systems.

Blotting, Northern↗
PubMed2004

In treating localized prostate cancer the efficacy of cryoablation is independent of DNA ploidy type.

While the prognostic value of DNA ploidy has been well established for radical prostatectomy, external beam radiation, brachytherapy and androgen deprivation therapy its role as a survival outcome predictor for prostate cancer patients treated with cryoablation has not yet been examined. Anecdotal evidence suggesting that cryoablation may be independent of DNA ploidy type led to the implementation of the current study. Retrospective analysis of data including flow digital cytometry was performed on 447 archival specimens taken from patients who had undergone cryosurgical ablation of primary prostate cancer. Five-year biochemical disease free survivals (bDFS) (defined as PSA thresholds of 0.5 and 1.0 ng/ml) were determined with Kaplan-Meier analysis. Patients were grouped according to DNA ploidy types then stratified by Gleason grade, risk group, pre-surgical PSA level, and disease stage. Mean and median age of the cohort was 65 and 64.6 years. Mean follow-up was 65.7 months. The DNA ploidy status of the population was found to be 59% diploid, 13% tetraploid, and 28% aneuploid. Using PSA < 1.0 ng/ml criterion, the bDFS rates for diploid, tetraploid, and aneuploid were 78%, 75%, and 79% respectively. The bDFS rates using a PSA < 0.5 ng/ml criterion were 67%, 59%, and 69% for diploid, tetraploid, and aneuploid groups. No significant outcome differences were found in stratified analysis. This investigation demonstrates that the efficacy of cryoablation is independent of DNA ploidy type.

Aged↗
PubMed2003

Nucleotide sequence homology requirements of HIV-1-specific short hairpin RNA.

The degradation of a selected mRNA species by RNA interference requires a high degree of homology between the short interfering or short hairpin RNA (si or shRNA) and its target. Recent reports have demonstrated that the number and location of nucleotide mismatches affect the activity of si/shRNA. Here, we systematically examined the effect of single nucleotide mutations in all 21 positions of an effective shRNA that targets the gag gene of HIV-1. We found that all mutant shRNAs exerted RNAi activity but were less effective in gene silencing compared to the wild-type gag shRNA. The most pronounced reduction in function was observed with mutations in the central and 5' regions of the shRNA. Our results demonstrate that optimal gene silencing requires perfect homology between shRNA and the chosen target, but that a variable degree of silencing occurs, depending upon the precise location of nucleotide mismatches.

Base Sequence↗
PubMed2003

Activation of the MAP kinase cascade by exogenous calcium-sensing receptor.

In Rat-1 fibroblasts and ovarian surface epithelial cells, extracellular calcium induces a proliferative response which appears to be mediated by the G-protein coupled calcium-sensing receptor (CaR), as expression of the nonfunctional CaR-R795W mutant inhibits both thymidine incorporation and activation of the extracellular-regulated kinase (ERK) in response to calcium. In this report we utilized CaR-transfected HEK293 cells to demonstrate that functional CaR is necessary and sufficient for calcium-induced ERK activation. CaR-dependent ERK activation was blocked by co-expression of the Ras dominant-negative mutant, Ras N17, and by exposure to the phosphatidyl inositol 3' kinase inhibitors wortmannin and LY294002. In contrast to Rat-1 fibroblasts, CaR-mediated in vitro kinase activity of ERK2 was unaffected by tyrosine kinase inhibitor herbimycin in CaR-transfected HEK293 cells. These results suggest that usage of distinct pathways downstream of the CaR varies in a cell-type specific manner, suggesting a potential mechanism by which activation of the CaR could couple to distinct calcium-dependent responses.

Animals↗
PubMed2003

Phase I pharmacokinetic and pharmacodynamic study of recombinant human endostatin in patients with advanced solid tumors.

PURPOSE: Endostatin is the first endogenous angiogenesis inhibitor to enter clinical trials. Laboratory investigations with endostatin have indicated broad antitumor activity coupled with remarkably low toxicity. A phase I trial of recombinant human endostatin was designed to evaluate toxicity and explore biologic effectiveness in patients with refractory solid tumors. PATIENTS AND METHODS: Endostatin was administered as a 1-hour intravenous infusion given daily for a 28-day cycle. A starting dose of 30 mg/m2 was explored with subsequent dose escalations of 60, 100, 150, 225, and 300 mg/m2. Assessment of serum pharmacokinetics was performed on all 21 patients. Western blot assay and mass spectroscopy were employed to evaluate endostatin metabolism. Circulating levels of endogenous proangiogenic growth factors were examined. Tumor and tumor blood supply were imaged by dynamic computed tomography (CT), magnetic resonance imaging, ultrasound, and positron emission tomography. RESULTS: Endostatin given on this schedule was essentially free of significant drug-related toxicity. Two transient episodes of grade 1 rash were observed. No clinical responses were observed. Endostatin pharmacokinetics were linear with dose, and serum concentrations were achieved that are associated with antitumor activity in preclinical models. No aggregate effect on circulating proangiogenic growth factors were seen, although several patients exhibited persistent declines in vascular endothelial growth factor levels while enrolled in the study. A few patients demonstrated changes in their dynamic CT scans suggestive of a decline in microvessel density, although overall, no consistent effect of endostatin on tumor vasculature was seen. CONCLUSION: Endostatin given daily as a 1-hour intravenous infusion was well tolerated without dose-limiting toxicity at doses up to 300 mg/m2.

Adult↗
PubMed2003

Salvage cryosurgery for recurrent prostate cancer after radiation therapy: a seven-year follow-up.

Cryosurgery of the prostate presents as an efficient therapy following failed radiation therapy. We report on a 7-year retrospective analysis evaluating the morbidity adn biochemical disease-free survival(bDFS) of this therapy. Between 1993 and 2001, 59 patients who had been previously treated with radiation therapy and had rising serum prostate-specific antigen(PSA) values underwent salvage cryoablation of the prostate for localized, histologically proven, recurrent prostate cancer. Serial serum PSA testing was performed, and biopsies were taken at 6, 12, and 24 months, and again at 5 years, and any time the PSA rose above 0.5 ng/mL. Patients were stratified along clinical parameters. The combined postsalvage bDFS rate using a PSA cutoff of 0.5 ng/mL was 59% and 69% with a 1.0 ng/mL PSA cut off. Using a PSA threshold of 0.5 ng/mL as evidence of biochemical recurrence, 61%, 62%, and 50% of patients with <4 ng/mL, 4-10 ng/mL, and > 10 ng/mL PSA, respectively, remain biochemically relapse free at 7 years. A threshold of 1.0 ng/mL yielded a disease-free status of 78%, 74%, and 46% respectively. Patients biopsies showed no evidence of residual or recurrent disease. Improved survival rates and no known latent complications indicate cryosurgery is a promising form of treatment for radiation-resistant prostate cancer. This 7-year analysis shows a promising validation of cryosurgery as an efficacious treatment modality for locally confined T1-T3 prostate cancer following primary radiation therapy failure.

Aged↗
PubMed2003

Inspiring patient loyalty, not satisfaction.

The distinction between loyalty and satisfaction is a significant one that requires staff to go above and beyond what is expected (i.e., satisfaction). In Lee's experience, most stories of patient loyalty have to do with empathy, caring and compassion.

Attitude of Health Personnel↗
PubMed2002

Targeted cryoablation of the prostate: 7-year outcomes in the primary treatment of prostate cancer.

The efficacy and safety of the long-term experience with targeted cryoablation of prostate cancer (TCAP) at a community hospital is retrospectively reviewed. A series of 590 consecutive patients who underwent TCAP as primary therapy with curative intent for localized or locally advanced prostate cancer from March 1993 to September 2001 were identified. Patients were stratified into 3 risk groups according to clinical characteristics. Biochemical disease-free survival (bDFS), post-TCAP biopsy results, and post-TCAP morbidity were calculated and presented. The mean follow-up time for all patients was 5.43 years. The percentages of patients in the low-, medium-, and high-risk groups were 15.9%, 30.3%, and 53.7%, respectively. Using a prostate-specific antigen (PSA)-based definition of biochemical failure of 0.5 ng/mL, results were as follows: (1) the 7-year actuarial bDFS for low-, medium-, and high-risk patients were 61%, 68%, and 61%, respectively; (2) the bDFS probabilities for a PSA cutoff of 1.0 ng/mL for low-, medium-, and high-risk patients were 87%, 79%, and 71%, respectively; and (3) the bDFS probabilities for low-, medium-, and high-risk patients using the American Society for Therapeutic Radiology and Oncology (ASTRO) definition of biochemical failure (3 successive increases of PSA level) were 92%, 89%, and 89%, respectively. The rate of positive biopsy was 13%. After a positive biopsy, 32 patients underwent repeat cryoablation. For those patients who underwent repeat cryoablation, 68%, 72%, and 91% remain bDFS using definitions of 0.5 ng/mL, 1.0 ng/mL, and the ASTRO criteria, respectively, after a mean follow-up time since repeat cryoablation of 63 months. The rates of morbidity were modest, and no serious complications were observed. TCAP was shown to equal or surpass the outcome data of external-beam radiation, 3-dimensional conformal radiation, and brachytherapy. These 7-year outcome data provide compelling validation of TCAP as an efficacious treatment modality for locally confined and locally advanced prostatic carcinoma.

Aged↗
PubMed2002

Phosphatidylinositol 3-kinase-dependent, MEK- independent proliferation in response to CaR activation.

Although ovarian surface epithelial (OSE) cells are responsible for the majority of ovarian tumors, we know relatively little about the pathway(s) that is responsible for regulating their proliferation. We found that phosphatidylinositol 3-kinase (PI3K) is activated in OSE cells in response to elevated extracellular calcium, and the PI3K inhibitors wortmannin and LY-294002 inhibited extracellular signal-regulated kinase (ERK) activation by approximately 75%, similar to effects of the mitogen-activated protein kinase/ERK kinase inhibitor PD-98059. However, in assays of proliferation, we found that PD-98059 inhibited proliferation by approximately 50%, whereas wortmannin inhibited >90% of the proliferative response to elevated calcium. Expression of a dominant negative PI3K totally inhibited ERK activation in response to calcium. These results demonstrate that ERK activation cannot account for the full proliferative effect of elevated calcium in OSE cells and suggest the presence of an ERK-independent, PI3K-dependent component in the proliferative response.

Calcium↗