Long-term Potency Research Articles

Improved Endothelialization of Titanium Vascular Implants by Extracellular Matrix Secreted from Endothelial Cells

A variety of metals have been widely used in construction of cardiovascular implants (CVIs), such as artificial heart valves, ventricular pumps, and vascular stents. Although great effects have been put into rigorous anticoagulation, late thrombosis still occurred due to inferior blood and cell compatibility. Natural endothelium is popularly regarded as the only substance that has long-term anticoagulant ability. So, establishment of a compact endothelial cell (EC) monolayer on CVIs surface is a guarantee for their long-term potency. In the work described here, titanium (Ti) disks were coated with extracellular matrix (ECM) directly secreted by human umbilical vein endothelial cells (HUVECs), so as to help ECs proliferate and migrate and to improve their endothelialization in vivo. Deposition of ECM on Ti disks was detected by immunofluorescence microscopy, diffuse reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The surface topography and wettability of the Ti disks significantly changed after ECM deposition. Most importantly, it was found that ECM deposition inhibited platelet adhesion, stimulated EC proliferation, increased EC migration speed in vitro, and eventually accelerated the re-cellularization speed of Ti disks in vivo. These important results render it reasonable and feasible to modify CVIs with ECM secreted from ECs for improving their long-term potency.

Potent induction of B- and T-cell immunity against human carcinoembryonic antigen-expressing tumors in human carcinoembryonic antigen transgenic mice mediated by direct lentivector injection

The applicability of immunotherapy would be dramatically broadened to a greater number of recipients if direct "off-the-shelf" products could be engineered to engender functionally potent immune responses against true "self"-tumor antigens. This would obviate the need for ex vivo culture of dendritic cells or T cells on a patient-by-patient basis, for example. The carcinoembryonic antigen (CEA) is a glycoprotein expressed in normal gut epithelium that is up-regulated in the majority of colon cancers, non-small cell lung cancers, and half of all breast cancers. Such properties make CEA an excellent and important target for cancer immunotherapy. In this study, we show stabilization of 14-day established s.c. mGC4CEA tumors in human CEA (huCEA) transgenic mice following two direct low-dose injections of 0.15x10(6) transducing units of a lentiviral vector (LV) that directs expression of huCEA (LV-huCEA). This stabilization result was reproducible and detailed analyses including antibody assays, multiplex cytokine analyses on unstimulated splenocytes, lymph node cell characterizations, tetramer staining, and immunofluorescence staining of tumor sections showed that this outcome correlated with both a cellular and humoral immune response. Similar tumor outcomes were not seen when mice were vaccinated with a control LV that engineered expression of enGFP only. The long-term potency of this vaccination strategy was also studied and revealed the requirement for maintenance of tumor antigen-specific immunity for efficient tumor control. These data support the use of direct injections of low doses of LV-huCEA for enhancement of tumor immunotherapy directed against CEA.

Long-Term Potency After Iodine-125 Radiotherapy for Prostate Cancer and Role of Sildenafil Citrate

Long-Term Potency After Iodine-125 Radiotherapy for Prostate Cancer and Role of Sildenafil Citrate

Long-Term Potency After Iodine-125 Radiotherapy for Prostate Cancer and Role of Sildenafil Citrate

Long-Term Potency After Iodine-125 Radiotherapy for Prostate Cancer and Role of Sildenafil Citrate

Perspective in Progress of Cardiovascular Gene Therapy

Recent progress in molecular and cellular biology has developed numerous effective cardiovascular drugs. However, there are still a number of diseases for which no known effective therapy exists, such as peripheral arterial disease, ischemic heart disease, restenosis after angioplasty, vascular bypass graft occlusion, and transplant coronary vasculopathy. Currently, gene therapy is emerging as a potential strategy for the treatment of cardiovascular disease to treat such diseases despite of its limitations. The first human trial in cardiovascular disease was started in 1994 to treat peripheral vascular disease using vascular endothelial growth factor (VEGF). Since then, many different potent angiogenic growth factors have been tested in clinical trials to treat peripheral arterial disease. The results from these clinical trials seem to exceed expectations. Improvement of clinical symptoms in peripheral arterial disease and ischemic heart disease has been reported. In addition, another strategy for combating disease processes, the targeting of transcriptional processes, has been tested in a human trial. Genetically modified vein grafts transfected with decoy against E2F, an essential transcription factor in cell cycle progression, revealed apparent long-term potency in human patients. This review focuses on the future potential of gene therapy for the treatment of cardiovascular disease.

Long-term potency after iodine-125 radiotherapy for prostate cancer and role of sildenafil citrate

Objectives To assess the long-term sexual potency and attrition in sexual function after iodine-125 ( 125I) seed radiotherapy and the effect of sildenafil on radiation-induced erectile dysfunction (ED). Methods This prospective study consisted of 86 sexually active patients (mean age 63.5 ± 7.7 years) who underwent 125I seed implantation from 1997 to 1999 to treat low-volume prostate cancer (prostate-specific antigen less than 10 ng/mL, Gleason score 6 or less, stage T1-T2). All patients were followed up every 6 to 8 months for 4 years. Patients prescribed sildenafil citrate for ED completed the abridged five-item version of the International Index of Erectile Function (IIEF) and the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) questionnaires. Results The median follow-up was 49.7 months (range 36 to 66). Of 86 patients, 43 (50%) did not initiate drug therapy; and only 36 (83.7%) of the 43 were interviewed at 4 years. Twenty-three (63.8%) of the 36 patients had erections sufficient for vaginal penetration, with a total mean ± SD IIEF-5 score of 15.76 ± 1.13. The other 50% (43 of 86) initiated sildenafil citrate for treatment of ED after seed implantation, with a minimal follow-up of 6 months. At 4 years, 32 (74%) of the 43 were responding positively to sildenafil citrate, with a total IIEF-5 score of 18.3 ± 1.2. The mean EDITS ± SD score was 76.5 ± 3.2, and the spousal satisfaction rate was 72% (31 of 43). The dropout rate was 37% (16 of 43); 10 (63%) of the 16 discontinued because of a lack of efficacy, 3 (19%) because of a return of natural erections sufficient for vaginal penetration, and 3 (19%) discontinued because of side effects (headaches). Conclusions ED is a major long-term issue after 125I seed radiotherapy, with a long-term potency rate of 29%. Sildenafil citrate improves erections in most patients after 125I seed implantation.

Efficacy of Shunt Surgert for Refractory Low Flow Priapism: A Report on the Incidence of Failed Detumescence and Erectile Dysfunction

The reported success rate for surgical cavernosa-to-spongiosum shunts in patients with refractory low flow priapism is variable and yet it is reported to be as high as 100% in terms of achieving detumescence. The long-term potency rate after the introduction of the shunt procedure is also as high as 50%. We reviewed the efficacy of various shunts in terms of achieving detumescence and we clarified the rate of erectile dysfunction at long-term followup. Patients were included in the analysis if they had painful low flow priapism more than 4 hours in duration that was refractory to conservative management, ultimately requiring a surgical shunt. Data, including etiology, duration and initial treatment measures, were retrospectively compiled in the last 12 years and the type of surgical shunts performed were recorded. Followup erectile function was assessed by clinical notes and a telephone survey using the International Index of Erectile Function. Of the 28 consecutive patients included in the study 13 (46.4%) required more than 1 operation for failed detumesence, of whom 12 (92.3%) initially underwent a Winter shunt. Only 2 of the 20 men (10%) with available followup reported preservation of pre-morbid erectile function. Three men (15%) achieved partial erection without the assistance of oral or injectable agents. In contrast to previously reported success rates, approximately 50% of our patients required reoperation for failed detumescence following a cavernosa-to-spongiosum shunt. In our experience the Winter shunt was the least successful operation, whereas reoperation was uncommonly required following an Al-Ghorab or Quackels shunt. As many as 90% of our patients had erectile dysfunction at followup.

Robotic Assisted Laparoscopic Sural Nerve Grafting During Radical Prostatectomy: Initial Experience

Sural nerve grafting has been done in select patients undergoing radical prostatectomy with unilateral or bilateral wide excision of the neurovascular bundle in an effort to preserve potency. We describe a novel technique of laparoscopic sural nerve grafting after radical prostatectomy using the da Vinci (Intuitive Surgical, Mountain View, California) robot. The procedure was performed successfully in 3 potent men 48, 49 and 59 years old, respectively. In patient 1 the entire procedure was performed robotically using a 6 port transperitoneal approach. In patients 2 and 3 the robot was used only for sural nerve grafting and urethrovesical anastomosis, while radical prostatectomy was performed by conventional laparoscopy. After the completion of radical prostatectomy with deliberate wide resection of the 2 neurovascular bundles in patients 1 and 3, and unilateral excision of the left neurovascular bundle in patient 2 a plastic surgery team harvested 10 to 15 cm of sural nerve from the left calf. Sural nerve grafts were interposed robotically by placing 4 to 6 interrupted perineural stitches of 6 or 7-zero polypropylene sutures. Mean operative time was 6.5 hours, mean blood loss was 216 cc and mean hospital stay was 2.3 days. Surgical margins were focally positive at the apex in the patients 1 and 3. During a followup of 7, 5 and 1 months patient 1 reported penile engorgement with sildenafil not sufficient for penetration, patient 2 with unilateral nerve preservation was potent without any medication and patient 3 did not achieve any degree of erection, respectively. The da Vinci remote robotic system technically facilitates sural nerve grafting during laparoscopic radical prostatectomy. Long-term potency data are essential to validate the technical success.

Recent progress in gene therapy for cardiovascular disease.

Gene therapy is emerging as a potential strategy for the treatment of cardiovascular diseases, such as peripheral arterial disease, ischemic heart disease, restenosis after angioplasty, vascular bypass graft occlusion and transplant coronary vasculopathy, for which no known effective therapy exists. The first human trial in cardiovascular disease started in 1994 treating peripheral vascular disease with vascular endothelial growth factor (VEGF) and since then, many different potent angiogenic growth factors have been tested in clinical trials for the treatment of peripheral arterial disease. In addition, therapeutic angiogenesis using the VEGF gene has been used to treat ischemic heart disease since 1997. The results from these clinical trials have exceeded expectations; improvement in the clinical symptoms of peripheral arterial disease and ischemic heart disease has been reported. Another strategy for combating the disease processes, targeting the transcriptional process, has been tested in a human trial. IN particular, transfection of cis-element double-stranded (ds) oligodeoxynucleotides (ODN) (= decoy) is a powerful tool in a new class of anti-gene strategies. Transfection of ds-ODN corresponding to the cis sequence will attenuate the authentic cis-trans interaction, leading to removal of trans-factors from the endogenous cis-elements and subsequent modulation of gene expression. Genetically modified vein grafts transfected with a decoy against E2F, an essential transcription factor in cell cycle progression, appear to have long-term potency in human patients. There is great potential in gene therapy for cardiovascular disease.

Potency preservation after three-dimensional conformal radiotherapy for prostate cancer: preliminary results.

We sought to assess potency preservation after three-dimensional conformal radiotherapy (3D-CRT) in prostate cancer patients eligible for radical prostatectomy, conventional radiotherapy, 3D-CRT, or transperineal prostate implantation. Patients with more advanced disease are commonly treated with hormonal therapy, which can cause impotence, and were consequently excluded from the analysis. Between December 1991 and June 1998, 198 prostate cancer patients were treated with 3D-CRT at the University of California, Davis Medical Center. Fifty-two of these patients had a pretreatment prostate-specific antigen (PSA) level of 10.0 ng/ml or less, a Gleason score of 6 or less, and a 1997 AJCC clinical stage T1bN0M0 to T2bN0M0. One patient was not evaluable. None of the 51 evaluable patients had diabetes mellitus. In 40 patients, the prostate gland only was irradiated to a total dose of 66 to 79.2 Gy by using daily 1.8-Gy fractions. In 11 patients, the prostate and seminal vesicles were treated to 44 to 55.8 Gy. Lymph nodes were not included in the clinical target volume. The median age was 68 years, and the median length of follow-up was 15 months. Potency in this study is defined as an erection sufficient for vaginal penetration. Kaplan-Meier analysis was used to describe potency as a function of time after 3D-CRT. Of the 51 evaluable patients, 35 (69%) were potent, 15 were impotent, and 1 was sexually inactive before 3D-CRT. Kaplan-Meier estimates of the potency preservation rates 1, 2, and 3 years after 3D-CRT are 100%, 83%, and 63%, respectively. On multivariate analysis, age, total radiation dose, and a history of transurethral resection of the prostate did not significantly affect potency preservation rates. Three (43%) of 7 patients who became impotent after 3D-CRT and used sildenafil were subsequently able to achieve erections sufficient for vaginal penetration. The preliminary results reported herein suggest that approximately two thirds of prostate cancer patients will retain their potency 3 years after 3D-CRT. Further follow-up is necessary to assess long-term potency after 3D-CRT. Sildenafil should be considered in patients who develop radiation-induced impotence.

HIV-I protease: Maturation, enzyme specificity, and drug resistance

Publisher Summary The active form of the 99-amino-acid-long mature protease (protease retropepsin (PR)) is a homodimer. Optimal catalytic activity of the mature PR and ordered processing of the polyproteins are critical for the liberation of infective progeny virus. The mature PR has proven to be the most effective target for antiviral therapy of AIDS. However, the long-term potency of current PR inhibitors as therapeutic agents is limited by the rapid development of drug-resistant variants of the PR. Therefore, it is critical to understand the molecular mechanisms of the proteolytic processes of the wild-type and drug-resistant mutants of PR to aid the development of new inhibitors and therapeutic strategies. This chapter discusses three critical features of the HIV-1 PR— namely, autocatalytic maturation from the precursor, substrate specificity, and emergence of drug resistance, utilizing protein and peptide design, enzyme kinetics, X-ray crystallography, and nuclear magnetic resonance (NMR) spectroscopy. The formation of the intermediate precursors under suboptimal conditions for the autoprocessing reaction is similar to that observed for the conversion of the zymogen form of the gastric protease pepsin that, unlike retroviral proteases, is a monomeric enzyme. Resistance to PR inhibitors can arise by more than one mechanism. Because no direct relationship was observed between relative catalytic activity, inhibition, and structural stability of the different PR mutants, drug resistance can arise from independent changes in any one of these parameters. Prolonged exposure to the drug can result in compensating mutations that act in combination to permit optimal polyprotein processing and replicative capacity in the presence of the PR inhibitor.

A lumped parameter model to evaluate the fluid dynamics of different coronary bypasses

Coronary bypass grafting is a surgical procedure frequently performed to obtain myocardial reperfusion downstream from severe coronary stenoses. Different surgical techniques may be adopted which include the use of graft made of internal mammary artery or saphenous vein, and the adoption of multiple or sequential bypasses for more than one stenosis. The haemodynamics of the surgically reconstructed coronary bed is strongly dependent on the bypass configuration and may induce atherogenic processes affecting the long-term potency of the bypass. We have improved a closed-loop mathematical model of the cardiovascular system including a more detailed description of the coronary tree which allows the calculation of the flow rate and pressure curves in all the vessels considered. Pathological situations, such as stenoses, have been simulated and investigated. Models of the internal mammary artery and of the saphenous vein have also been developed in order to simulate coronary artery bypasses. The four simulated bypass configurations have been the single saphenous vein, the sequential saphenous vein, the single internal mammary artery and the sequential internal mammary artery. Results of the simulations of the different bypass grafting configurations indicate that between single saphenous vein and single internal mammary artery the latter shows better haemodynamics both for the flow rate pattern and for the calculated wall shear stress. The sequential bypasses show better haemodynamics in comparison with the single bypass in the proximal segments and worse performance in the distal ones. The models may be applied as an investigative tool to evaluate actual cases of surgically treatable coronary stenoses. They can predict the modification in blood flow waveforms, mean velocities, shear stress and distribution of blood flow in the coronary branches as a function of the adopted bypass configuration.

Long-term control of plasma calcitriol concentration in dogs and humans. Dominant role of plasma calcium concentration in experimental hyperparathyroidism.

Despite great interest in the elevated circulating levels of calcitriol (1,25-[OH]2D) associated with the clinical syndrome of human primary hyperparathyroidism, the relative potencies of known and potential stimuli/suppressors of long-term calcitriol levels have not been evaluated in either clinical or experimentally induced hyperparathyroid states. Based on reports that aparathyroid animals exhibit suppressed plasma calcitriol concentration and that acute administration of parathyroid hormone (PTH) to both humans and experimental animals or to renal slices in vitro results in increased plasma calcitriol concentration/production rate, it might be predicted that a chronic experimental model of either hypercalcemic primary hyperparathyroidism or hypocalcemic secondary hyperparathyroidism would show increased plasma calcitriol concentration. Chronic alterations in plasma calcium concentration have not been implicated as modulating calcitriol levels in any species. Accordingly, we investigated the long-term response of plasma calcitriol concentration in states of sustained experimental primary and secondary hyperparathyroidism. Intact dogs (group I) undergoing continuous intravenous PTH infusion for 12 d developed sustained hypercalcemia and hypophosphatemia, and plasma calcitriol concentration decreased from 23 +/- 3 to 14 +/- 3 pg/ml (P less than 0.01). Subsequent chelator (EGTA)-induced chronic normalization of hypercalcemia during ongoing PTH infusion resulted in a large and sustained increase in plasma calcitriol concentration to supernormal levels, reversible during subsequent cessation of chelator infusion. In additional intact dogs (group II), chronic chelator-induced hypocalcemic secondary hyperparathyroidism resulted in a sustained increase in plasma calcitriol concentration despite hyperphosphatemia. In normal human subjects undergoing a 12-13-d continuous intravenous PTH infusion to result in sustained moderate hypercalcemia (12.0 +/- 0.2 mg/100 ml) and hypophosphatemia, plasma calcitriol concentration decreased significantly (P less than 0.01) as in group I dogs and was followed by reversal to normal levels in a recovery period. The present results provide strong evidence in both humans and dogs that during experimentally induced chronic PTH excess, alterations in plasma calcium concentration dictate the directional response of circulating calcitriol concentrations. The long-term potency of plasma calcium concentration as a modulator of calcitriol metabolism is sufficient to override opposing modulation by plasma phosphorus concentration and PTH.