Biomedical subjects

L Y Lee

Publications and source records attributed to L Y Lee.

At least 37 records · Page 2Linked to original sources

PubMed2001

Novel constructions to enable the integration of genes into the Agrobacterium tumefaciens C58 chromosome.

We constructed several versatile sets of vectors that can be used to introduce any gene into the pgl/picA locus of the Agrobacterium tumefaciens C58 chromosome without affecting T-DNA transfer. One set contains a fragment containing the lacIq and lacZ genes and a multiple cloning site from pBluescriptII SK(+) inserted into a PstI site between the pgl and picA genes on an incPalpha plasmid. The resulting plasmid contains eight unique restriction endonuclease sites and the ability to use blue-white screening for the presence of an insert. A second plasmid also contains a beta-lactamase gene within this locus and provides a convenient ampicillin-carbenicillin resistance marker for the selection of genes integrated into the chromosome following double homologous recombination (homogenotization). A third plasmid contains, in addition to the lacZ, lacIq, and beta-lactamase genes within the pgl/picA locus, a sacRB gene cassette within the vector to counterselect against the presence of the vector within A. tumefaciens. To test this system, we introduced a wild-type virD2 gene into the A. tumefaciens chromosome at the pgl/picA locus. When a Ti plasmid harboring a deletion of virD2 was in this strain, the integrated virD2 gene complemented the virD2 deletion and the resulting transformation phenotype was identical to that resulting from A. tumefaciens strains harboring a wild-type virD2 gene located on a replicating plasmid.

Agrobacterium tumefaciens↗

PubMed2001

Effects of human eosinophil granule-derived cationic proteins on C-fiber afferents in the rat lung.

Experiments were performed to test the hypothesis that human eosinophil granule-derived cationic proteins stimulate vagal C-fiber afferents in the lungs and elicit pulmonary chemoreflex responses in anesthetized Sprague-Dawley rats. Intratracheal instillation of eosinophil cationic protein (ECP; 1-2 mg/ml, 0.1 ml) consistently induced an irregular breathing pattern, characterized by tachypnea (change in breathing frequency of 44.7%) and small unstable tidal volume (VT). The tachypnea, accompanied by decreased heart rate and arterial blood pressure, started within 30 s after the delivery of ECP and lasted for >30 min. These ECP-induced cardiorespiratory responses were completely prevented by perineural capsaicin treatment of both cervical vagi, which selectively blocked C-fiber conduction, suggesting the involvement of these afferents. Indeed, direct recording of single-unit activities of pulmonary C-fibers further demonstrated that the same dose of ECP evoked a pronounced and sustained (>30-min) stimulatory effect on pulmonary C-fibers. Furthermore, the sensitivity of these afferents to lung inflation was also markedly elevated after the ECP instillation, whereas the vehicle of ECP administered in the same manner had no effect. Other types of eosinophil granule cationic proteins, such as major basic protein and eosinophil peroxidase, induced very similar respiratory and cardiovascular reflex responses. In conclusion, these results show that eosinophil granule-derived cationic proteins induce a distinct stimulatory effect on vagal pulmonary C-fiber endings, which may play an important role in the airway hyperresponsiveness associated with eosinophil infiltration in the airways.

Animals↗

PubMed2001

Chronic smoking enhances tachykinin synthesis and airway responsiveness in guinea pigs.

This study tests the hypothesis that the bronchial hyperreactivity induced by chronic cigarette smoke (CS) exposure involves the increased expression and release of tachykinins and calcitonin gene-related peptide (CGRP) from afferent nerve fibers innervating the airways. In guinea pigs chronically exposed to CS (20 min twice daily for 14-17 d), peak response in total lung resistance to capsaicin (1.68 microg/kg, intravenously) was significantly greater than that evoked by the same dose of capsaicin in control (air-exposed) animals. This augmented response in CS-exposed animals was abolished after treatment with CP-99994 and SR-48968, the neurokinin (NK)-1 and NK-2 receptor antagonists, suggesting the involvement of tachykinins in chronic CS-induced airway hyperresponsiveness (AHR). Further, substance P (SP)-like immunoreactivity (LI) and CGRP-LI in the airway tissue were significantly greater in the CS animals than in the control animals. Finally, beta-preprotachykinin (PPT, a splice variant from the PPT A gene encoding tachykinins including SP and NKA) messenger RNA levels as measured by in situ hybridization histochemistry displayed a significant increase in jugular ganglion neurons but not in dorsal root or nodose ganglion neurons. These data suggest that chronic CS-induced AHR is related to an increase in SP synthesis and release in jugular ganglion neurons innervating the lungs and airways.

Analysis of Variance↗

PubMed2001

Airway reflexes, autonomic function, and cardiovascular responses.

In this article, we review the cardiovascular responses to the inhalation of irritants and pollutants. Many sensory receptors in the respiratory system, from nose to alveoli, respond to these irritants and set up powerful reflex changes, including those in the cardiovascular system. Systemic hypotension or hypertension, pulmonary hypertension, bradycardia, tachycardia, and dysrhythmias have all been described previously. Most of the experiments have been acute and have been performed on anesthetized experimental animals. Experiments on humans suggest we have similar sensory systems and reflex responses. However, we must use caution when applying the animal results to humans. Most animal experiments, unlike those with humans, have been performed using general anesthesia, with irritants administered in high concentrations, and often to a restricted part of the respiratory tract. Species differences in the response to irritants are well established. We must be even more careful when applying the results of acute experiments in animals to the pathophysiologic changes observed in prolonged exposure to environmental pollution in humans.

Air Pollutants↗

PubMed2001

Modulation of airway sensitivity to inhaled irritants: role of inflammatory mediators.

Bronchopulmonary C-fiber endings and rapidly adapting pulmonary receptors (RARs) are primarily responsible for eliciting the defense reflexes in protecting the lungs against inhaled irritants. In anesthetized animals, inhalation of cigarette smoke, one of the common inhaled irritants, into the lungs elicits pulmonary chemoreflexes that are mediated through the stimulation of pulmonary C fibers. When the C-fiber conduction is selectively blocked in the vagus nerves, the same smoke inhalation triggered only augmented breaths, a reflex effect of activating RARs, in the same animals. Indeed, electrophysiologic study shows that inhaled smoke exerts a direct stimulatory effect on both types of afferents. Increasing evidence indicates that the excitability of these afferents and therefore their reflex actions are enhanced by airway mucosal inflammation; one such example is the airway hyperresponsiveness induced by acute exposure to ozone. Although the mechanism underlying the inflammation-induced hypersensitivity of C-fiber endings is not fully understood, the possible involvement of local release of certain inflammatory mediators, such as histamine and prostaglandin E(2) (PGE(2), should be considered. It is believed that changes in the membrane properties mediated by the activation of certain specific receptor proteins located on the membrane of these nerve terminals are involved, as the sensitizing effects of PGE(2) can be also demonstrated in cultured pulmonary C neurons.

Air Pollutants↗

PubMed2000

The human papillomavirus type 16 E6 and E7 oncoproteins cooperate to induce mitotic defects and genomic instability by uncoupling centrosome duplication from the cell division cycle.

Loss of genomic integrity is a defining feature of many human malignancies, including human papillomavirus (HPV)-associated preinvasive and invasive genital squamous lesions. Here we show that aberrant mitotic spindle pole formation caused by abnormal centrosome numbers represents an important mechanism in accounting for numeric chromosomal alterations in HPV-associated carcinogenesis. Similar to what we found in histopathological specimens, HPV-16 E6 and E7 oncoproteins cooperate to induce abnormal centrosome numbers, aberrant mitotic spindle pole formation, and genomic instability. The low-risk HPV-6 E6 and E7 proteins did not induce such abnormalities. Whereas the HPV-16 E6 oncoprotein has no immediate effects on centrosome numbers, HPV-16 E7 rapidly induces abnormal centrosome duplication. Thus our results suggest a model whereby HPV-16 E7 induces centrosome-related mitotic disturbances that are potentiated by HPV-16 E6.

Carcinoma, Squamous Cell↗

PubMed2000

Antirestriction protein Ard (Type C) encoded by IncW plasmid pSa has a high similarity to the "protein transport" domain of TraC1 primase of promiscuous plasmid RP4.

The IncW plasmid pSa contains the gene ard encoding an antirestriction function that is specific for type I restriction and modification systems. The nucleotide sequence of ard was determined and an appropriate polypeptide of about 33 kDa was identified in Escherichia coli T7 expression system. Analysis of deduced amino acid sequence of Ard encoded by pSa revealed that this protein has no significant similarities with the known Ard proteins (ArdA and ArdB types) except the "antirestriction" motif (14 amino acid residues in length) conserved for all known Ard proteins. This finding suggests that pSa Ard may be classified as a new type of Ard proteins which we designated ArdC. The remarkable feature of ArdC is that it has a high degree of similarity (about 38 % identity) to the N-terminal region of RP4 TraC1 primase which includes about 300 amino acid residues and seems to be essential for binding to the single-stranded DNA and TraC1 protein transport to the recipient cells during the conjugal transfer of plasmid DNA. ArdC also binds to single-stranded DNA. In addition, this protein is able in vitro to protect the single-stranded but not double-stranded plasmid DNA against the activity of type II restriction endonuclease HhaI that cleaves both single and double-stranded DNA. We suggest that like TraC1, ArdC would be transported as a result of their interaction with the single-stranded DNA of transferred plasmid strand during conjugative passage through the cell envelope to the recipient bacterium. Such properties of ArdC protein might be useful to protect immediately the incoming single-stranded DNA from the host endonucleases.

Amino Acid Sequence↗

PubMed2000

Use of quantitative TaqMan real-time PCR to track the time-dependent distribution of gene transfer vectors in vivo.

To assess the biodistribution and pharmacokinetics of gene transfer vectors, real-time PCR with fluorescent TaqMan chemistry was used to quantify tissue levels of adenovirus gene transfer vectors (Ad) following myocardial administration. After optimizing the detection of the genome of Ad vectors expressing human vascular endothelial growth factor (Ad(GV)VEGF121.10) and Escherichia coli cytosine deaminase (Ad(GV)CD.10), a comparison was made of intramyocardial injection versus intracoronary delivery to the left ventricle of the pig. One hour post-intramyocardial administration, the left ventricular Ad genome level was 6.2 copies per cellular genome, 26-fold higher than the level of 0.24 copies per cellular genome following intracoronary administration. Relative to the vector levels after 1 h, the amount dropped 14- and 5.5-fold by 24 h following intramyocardial and intracoronary administration, respectively. Interestingly, the vector that escaped the left ventricle after intracoronary or intramyocardial administration to pigs was found primarily within the lung, an observation in marked variance to the biodistribution of Ad vector in rodents. In this regard, after intravenous injection to the pig, 90% of the recovered vector was found in the lung, and even after intrahepatic portal vein injection, 55% of the recovered vector was in the lung. These data have important implications regarding the use of experimental animals for safety studies on administration of Ad to humans.

Adenoviridae↗

PubMed2000

Transmyocardial laser revascularization with excimer laser: clinical results at 1 year.

BACKGROUND: Transmyocardial laser revascularization, a new strategy for the treatment of diffuse ischemic heart disease, uses laser technology for the theoretical purpose of forming transmyocardial channels in the heart to increase perfusion to ischemic zones. This report summarizes our initial clinical experience with the procedure. METHODS: Excimer transmyocardial laser revascularization was performed in a reversibly ischemic region of the heart in 15 patients. Ischemia and myocardial viability were evaluated by assessment of symptoms and of results of radionuclide single photon emission computed tomography imaging, exercise tolerance testing, and 24-hour Holter monitoring. RESULTS: No adverse events occurred as a result of the laser revascularization, although 1 patient with preoperative ventricular arrhythmias died 48 hours postoperatively as a result of refractory ventricular tachycardia. Angina class decreased significantly from base line values in patients who had undergone the procedure (mean Canadian Cardiovascular Association angina class, 3.5+/-0.5 at base line, 1.6+/-0.6 at 1 month, 1.5+/-0.8 at 3 months, 1.9+/-0.9 at 6 months, 1.8+/-0.8 at 12 months; p<0.002), and nitroglycerin requirements were similarly decreased in patients who had undergone laser revascularization (mean g/wk of sublingual nitroglycerin, 19+/-4 at baseline, 5+/-3 at 1 month, 4+/-2 at 3 months, 4+/-2 at 6 months, 2+/-1 at 12 months; p<0.02). Exercise tolerance testing demonstrated increase in exercise duration compared with base line values (mean minutes, 7.4+/-3.1 at base line, 8.0+/-3.9 at 1 month, 8.5+/-4.4 at 3 months, and 9.0+/-3.9 at 12 months; p>0.05); those increases were not large enough to be statistically significant, however. CONCLUSIONS: Our data are consistent with the concept that excimer transmyocardial laser revascularization in individuals with significant ischemic heart disease appears to be well tolerated, can be performed safely, and may lead to a reduction in ischemic symptomatology.

Adult↗

PubMed2000

Focal angiogen therapy using intramyocardial delivery of an adenovirus vector coding for vascular endothelial growth factor 121.

BACKGROUND: Adenovirus (Ad) vector-mediated gene therapy strategies have emerged as promising modalities for the "biological revascularization" of tissues. We hypothesized that direct intramyocardial, as opposed to intracoronary, administration of an Ad vector coding for the vascular endothelial growth factor 121 cDNA (Ad(GV)VEGF121.10) would provide highly focal Ad genome levels, and increases in VEGF, ideal for inducing localized therapeutic angiogenesis. METHODS: Persistence and regional distribution of the vector were assessed by TaqMan real-time quantitative polymerase chain reaction technology and enzyme-linked immunosorbent assay, after intramyocardial Ad(GV)VEGF121.10 in the rat, and either intramyocardial or intracoronary (circumflex territory) vector in Yorkshire swine. Based on these results, we assessed the focal nature of the improved cardiac blood flow in a previously reported porcine myocardial ischemia model. RESULTS: Intramyocardial delivery of Ad(GV)VEGF121.10 in the rat resulted in local persistence of the Ad genome that decreased 1,000-fold over 3 weeks, with peak myocardial VEGF expression 24 to 72 h after vector delivery. After intramyocardial Ad(GV)VEGF121.10 in the circumflex distribution of pigs, Ad vector genome and VEGF protein levels were more than 1,000-fold and more than 90-fold higher, respectively, in this distribution than in other myocardial regions. In comparison, intracoronary injection yielded maximum myocardial Ad genome and VEGF levels 33-fold and 9-fold lower, respectively, than that after intramyocardial delivery. Angiograms obtained 28 days after intramyocardial Ad(GV)VEGF121.10 demonstrated rapid circumflex reconstitution via collaterals localized to the region of vector administration. CONCLUSIONS: These studies demonstrate that direct intramyocardial administration of Ad(GV)VEGF121.10 results in focal genome and VEGF levels, including focal angiogenesis, sufficient to normalize blood flow to the ischemic myocardium, findings that are relevant to designing human trials of gene therapy-mediated cardiac angiogenesis.

Adenoviridae↗

PubMed2000

Airway hyperresponsiveness to cigarette smoke in ovalbumin-sensitized guinea pigs.

This study was carried out to determine if the bronchoconstrictive effect of cigarette smoke (CS) is enhanced when airway hyperresponsiveness is induced by ovalbumin (Ova) sensitization, and if so, whether an increase in endogenously released tachykinins is involved. The bronchoconstrictive effects of an acute CS inhalation challenge (15 ml; 50% concentration) were compared between guinea pigs sensitized with aerosolized Ova and matching control animals (receiving saline aerosol). In Ova-sensitized animals, there were marked increases in the numbers of eosinophils and neutrophils in the bronchoalveolar lavage fluid (BALF), which was accompanied by an elevated bronchomotor response to acetylcholine (ACh). The baseline lung resistance (RL) and dynamic pulmonary compliance (Cdyn) were not significantly different between the two groups; however, the same CS inhalation challenge evoked a significantly more intense bronchoconstriction in the Ova-sensitized group (control group: DeltaRL = 68 +/- 8%, DeltaCdyn = -26 +/- 6%; Ova group: DeltaRL = 425 +/- 76%; DeltaCdyn = -47 +/- 8%). The levels of substance P-like immunoreactivity (SP-LI) and calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) measured in the bronchoalveolar lavage (BAL) collected after CS inhalation challenge were also significantly greater in Ova-sensitized animals than in control animals. Furthermore, pretreatment with SR-48968, a selective antagonist of neurokinin-2 (NK(2)) receptor, inhibited more than 85% of the enhanced bronchomotor responses to CS challenge, but did not significantly reduce the airway hyperresponsiveness to ACh in Ova-sensitized guinea pigs. These results show that Ova sensitization induces airway hyperresponsiveness to inhaled CS, and that the endogenous tachykinins evoked by CS-induced activation of lung C fibers play a primary role in this augmented response.

Acetylcholine↗

PubMed2000

Prostaglandin E(2) enhances chemical and mechanical sensitivities of pulmonary C fibers in the rat.

It has been recently reported that pulmonary reflex responses to injection or inhalation challenge of capsaicin are enhanced by exogenous Prostaglandin E(2) (PGE(2)). The present study was carried out to determine whether PGE(2) enhances the stimulatory effects of chemical stimulants and lung inflation on vagal pulmonary C fibers, and if so, whether the excitabilities of other types of lung afferents are also augmented by PGE(2). In anesthetized, open-chest rats, administration of PGE(2) (1.5 microgram/kg/min for 2 min) did not significantly change the baseline activity of vagal pulmonary C fibers, but it markedly enhanced the stimulatory effects of both low (0.25 microgram/kg) and high doses (0.5 microgram/kg) of capsaicin on these fibers. Similarly, potentiating effects of PGE(2) were found on the pulmonary C-fiber responses to injections of lactic acid and adenosine, although considerable variability existed in the degrees of potentiation between the different stimulants. Furthermore, PGE(2) infusion also significantly enhanced the C-fiber response to constant-pressure lung inflation (tracheal pressure [Pt] = 30 cm H(2)O). In contrast, PGE(2) did not alter the responses of either slowly adapting pulmonary receptors or rapidly adapting pulmonary receptors to lung inflation. In summary, these results show that the sensitivity of pulmonary C-fiber afferents to both mechanical and chemical stimuli is enhanced by PGE(2), suggesting that endogenous release of this autocoid may play a part in the airway irritation and dyspneic sensation associated with airway inflammation.

Animals↗

PubMed2000

Splenic abscess--a changing trend in treatment.

Fifteen patients with splenic abscesses were evaluated between 1985 and 1995. The most common predisposing factors were remote infection, diabetes mellitus and heart disease. Common clinical presentations included leucocytosis, fever, left upper quadrant abdominal pain and left pleural effusion. Four patients with splenic abscesses smaller than 4 cm in diameter were treated with antibiotics alone, and 1 in this treatment group died. Among the 10 patients with splenic abscesses larger than 4 cm in diameter receiving percutaneous drainage, 9 (90%) were successfully cured, including 8 with unilocular abscesses and 1 with multilocular abscesses. Two patients underwent splenectomy. In conclusion, percutaneous drainage using ultrasound or computed tomography guidance may be recommended as the treatment of choice for splenic abscess larger than 4 cm in diameter. Antibiotics alone may sometimes be considered for splenic abscesses smaller than 4 cm in diameter. Splenectomy is reserved for those cases where medical treatment has failed.

Abscess↗

PubMed1999

Angiogenesis gene therapy: phase I assessment of direct intramyocardial administration of an adenovirus vector expressing VEGF121 cDNA to individuals with clinically significant severe coronary artery disease.

BACKGROUND: Therapeutic angiogenesis, a new experimental strategy for the treatment of vascular insufficiency, uses the administration of mediators known to induce vascular development in embryogenesis to induce neovascularization of ischemic adult tissues. This report summarizes a phase I clinical experience with a gene-therapy strategy that used an E1(-)E3(-) adenovirus (Ad) gene-transfer vector expressing human vascular endothelial growth factor (VEGF) 121 cDNA (Ad(GV)VEGF121.10) to induce therapeutic angiogenesis in the myocardium of individuals with clinically significant coronary artery disease. METHODS AND RESULTS: Ad(GV)VEGF121.10 was administered to 21 individuals by direct myocardial injection into an area of reversible ischemia either as an adjunct to conventional coronary artery bypass grafting (group A, n=15) or as sole therapy via a minithoracotomy (group B, n=6). There was no evidence of systemic or cardiac-related adverse events related to vector administration. In both groups, coronary angiography and stress sestamibi scan assessment of wall motion 30 days after therapy suggested improvement in the area of vector administration. All patients reported improvement in angina class after therapy. In group B, in which gene transfer was the only therapy, treadmill exercise assessment suggested improvement in most individuals. CONCLUSIONS: The data are consistent with the concept that direct myocardial administration of Ad(GV)VEGF121.10 to individuals with clinically significant coronary artery disease appears to be well tolerated, and initiation of phase II evaluation of this therapy is warranted.

Adenoviridae↗

PubMed1999

Safety of direct myocardial administration of an adenovirus vector encoding vascular endothelial growth factor 121.

A gene therapy strategy involving direct myocardial administration of an adenovirus (Ad) vector encoding the vascular endothelial growth factor 121 cDNA (Ad(GV)VEGF121.10) has been shown to be capable of "biological revascularization" of ischemic myocardium in an established porcine model [Mack, C.A. (1998). J. Thorac. Cardiovasc. Surg. 115, 168-177]. The present study evaluates the local and systemic safety of this therapy in this porcine ischemia model and in normal mice. Myocardial ischemia was induced in Yorkshire swine with an ameroid constrictor 21 days prior to vector administration. Ad(GV)VEGF121.10 (10(9) or 10(10) PFU), Ad5 wild type (10(9) PFU), AdNull (control vector with no transgene; 10(9) PFU), saline, or no injection (naive) was administered in 10 sites in the ischemic, circumflex distribution of the myocardium. Toxicity was assessed by survival, serial echocardiography, blood analyses, and myocardial and liver histology at 3 and 28 days after vector administration. All pigs survived to sacrifice, except for one animal in the Ad(GV)VEGF121.10 (10(10) PFU) group, which died as a result of oversedation. Echocardiograms of Ad(GV)VEGF121.10-treated pigs demonstrated no differences in pericardial effusion, mitral valve regurgitation, or regional wall motion compared with control pigs. Intramyocardial administration of Ad(GV)VEGF121.10 included only minimal myocardial inflammation and necrosis, and no hepatic inflammation or necrosis. Only a mild elevation of the white blood cell count was encountered on day 3, which was transient and self-limited in the Ad(GV)VEGF121.10 group as compared with the saline-treated animals. As a measure of inadvertent intravascular administration of vector, normal C57/BL6 mice received intravenous Ad(GV)VEGF121.10 (10(4), 10(6), 5 x 10(7), or 10(9) PFU), AdNull (5 x 10(7) or 10(9) PFU), or saline. Toxicity was assessed by survival, blood analyses, and organ histology at 3 and 7 days after vector administration. A separate group of C57/BL6 mice received intravenous AdmVEGF164 (Ad vector encoding the murine VEGF164 cDNA), Ad(GV)VEGF121.10, AdNull (10(8) PFU each group), or saline to assess duration of expression and safety of a homologous transgene. All mice survived to sacrifice except for 40% of the mice in the highest (10(9) PFU; a dose more than 10(3)-fold higher by body weight than the efficacious dose in pigs) Ad(GV)VEGF121.10 dose group, which died on days 5-6 after vector administration. The only differences seen in the blood analyses between treated and control mice were in the very high Ad(GV)VEGF121.10 dose group (10(9) PFU), which demonstrated an anemia as well as an increase in alkaline phosphatase when compared with all other treatment groups. Hepatic VEGF levels by ELISA in AdmVEGF164-treated mice did not persist beyond 14 days after vector administration, suggesting that persistent expression of a homologous VEGF gene transferred with an Ad vector is not a significant safety risk. Although this is not a chronic toxicity study, these data demonstrate the safety of direct myocardial administration of Ad(GV)VEGF121.10, and support the potential use of this strategy to treat human myocardial ischemia.

Adenoviruses, Human↗

PubMed1999

Polarized expression and function of the costimulatory molecule CD58 on human intestinal epithelial cells.

BACKGROUND & AIMS: Intestinal epithelial cells (IECs) can process foreign protein antigens and display antigenic peptides to CD4(+) T lymphocytes via HLA class II molecules. The purpose of this study was to determine the nature of the second, or costimulatory, signal provided by IECs. METHODS: We investigated surface expression of the costimulatory molecules CD58 (LFA-3), CD80 (B7-1), and CD86 (B7-2) by using flow cytometry, confocal microscopy, and vectorial biotinylation. Antibodies specific for CD58, CD80, and CD86 were used in blocking experiments to assess the role of these molecules in providing a costimulatory signal to CD4(+) T cells by IECs. RESULTS: CD58, but not CD80 or CD86, was observed to be expressed constitutively on both native IECs and in the IEC lines T84 and HT-29. The surface expression of CD58 was highly polarized and restricted to the basolateral surface of the cell. Antibodies against CD58, but not CD80 or CD86, inhibited the stimulation of CD4(+) T-cell proliferation mediated by IECs. CONCLUSIONS: CD58 is expressed by polarized IECs in a topologically restricted manner at the region of T-cell contact and can function as a costimulatory molecule in HLA class II-mediated antigen presentation.

Antibodies↗

PubMed1999

Exogenous control of cardiac gene therapy: evidence of regulated myocardial transgene expression after adenovirus and adeno-associated virus transfer of expression cassettes containing corticosteroid response element promoters.

OBJECTIVE: Because of the relative inaccessibility of the heart for repeated gene therapy, it would be useful to regulate the expression of transgenes delivered in a single dose of a gene therapy vector. Incorporation into the vector of a regulatable promoter that is responsive to pharmacologic agents that are widely used and well tolerated in clinical practice represents such a control strategy. METHODS: A replication-deficient adenovirus or an adeno-associated virus containing a chimeric promoter composed of 5 glucocorticoid response elements and the murine thrombopoietin complementary DNA (AdGRE.mTPO or AAVGRE.mTPO) was administered to the hearts of Sprague-Dawley rats. Platelet levels were evaluated as a reporter of transgene activity with or without dexamethasone. For comparison, rats received a control adenovirus vector, AdCMV.mTPO or AdCMV.Null, and the control adeno-associated virus vector AAVCMV.luc, which encodes for the firefly luciferase (luc) gene. RESULTS: Platelet elevation in the AdGRE.mTPO group peaked 4 days after dexamethasone administration, with a return to baseline 1 week after the initial corticosteroid dose. Subsequent dexamethasone administration at 2 and 4 weeks resulted in similar but progressively decreased responses. The AAVGRE.mTPO group had 5 peak platelet levels to a minimum of 2.2-fold with respect to baseline without diminution with subsequent dexamethasone administrations out to 169 days. In contrast, the AdCMV.Null and AAVCMV.luc groups demonstrated no increase in platelet counts and the AdCMV.mTPO group demonstrated a slow rise to a single peak platelet count independent of dexamethasone administration. CONCLUSION: It may be possible to control on demand the expression of a gene transferred to the heart. This strategy should be useful in cardiac gene therapy.

Animals↗

PubMed1999

Transmyocardial laser revascularization and angiogenesis: the potential for therapeutic benefit.

Transmyocardial laser revascularization (TMR) has emerged as a promising therapy for ischemic heart disease in patients who are not candidates for more conventional therapies such as percutaneous transluminal coronary angioplasty or coronary artery bypass grafting. Although TMR provides symptomatic relief of angina and improved cardiovascular performance in a select patient population, the mechanism by which TMR works is still a controversial issue. Recently, it has been postulated that TMR evokes an angiogenic response and thereby improves local perfusion to ischemic myocardial territories. Herein we present a review of TMR and the molecular basis of angiogenesis.

Animals↗