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Biomedical subjects

J L Cook

Publications and source records attributed to J L Cook.

At least 91 records · Page 5Linked to original sources
PubMed1996

Adenovirus-mediated in vivo gene transfer in a rabbit model of allograft vasculopathy.

BACKGROUND: The long-term success of heart transplantation continues to be in jeopardy because of the development of accelerated vascular myointimal proliferation. Transfer of genes encoding products that can modulate the adverse consequences of phenomena that cause myointimal proliferation, into the allograft vessel wall, may modify these pathologic processes. The purpose of this study was to assess the feasibility of gene transfer and to evaluate the duration of gene expression in a rabbit heterotopic aortic transplant model of allograft vasculopathy. METHODS: The abdominal aortas of 32 outbred New Zealand rabbits were harvested and cross-sectionally bisected (n = 64). Six donor and recipient animals were used in a preliminary study to examine neointimal proliferation without accompanying gene transfer. Of the remaining 26 rabbits (52 allografts), one half of each allograft aorta was administered a control solution, while the other half was incubated with a replication-defective, recombinant, adenoviral vector-encoding, cytomegalovirus promoter-regulated beta-galactosidase. After a 20-minute incubation period, bilateral aorto-carotid transplantations were performed in 26 recipient rabbits. All animals received cyclosporine immunosuppression (10 mg/kg/day subcutaneously). The allografts were harvested at 3, 7, 10, 21, and 28 days after transplantation and assayed for beta-galactosidase activity. RESULTS: Neointimal areas showed an initially slow increase for the first 10 days, followed by a rapid increase up to 21 days, and tended to plateau thereafter. Significant beta-galactosidase was apparent in aortic sections dissected from host rabbits for all time points, except at 28 days. At the 21-day time point, the aortic section from one rabbit was positive, whereas the other two remained negative. However, the one positive section showed intense beta-galactosidase activity, suggesting variability in the experimental model. At 28 days, all aortic sections were negative. CONCLUSIONS: Our findings confirm that genes delivered by this method are expressed for the duration of early rapid intimal proliferation in this heterotopic rabbit model of aortic allograft vasculopathy. These findings suggest that this animal model can be used to assess the therapeutic potential of gene transfer at the time of vascular transplantation and may provide a novel therapeutic approach to prevent or ameliorate the genesis of allograft vasculopathy.

Adenoviruses, Human↗
PubMed1996

Experiences with a distributed virtual patient record system.

TeleMed is a distributed diagnosis and analysis system, which permits physicians who are not collocated to consult on the status of a patient. The patient's record is dynamically constructed from data that may reside at several sites but which can be quickly assembled for viewing by pointing to the patient's name. Then, a graphical patient record appears, through which consulting physicians can retrieve textual and radiographic data with a single mouse click. TeleMed uses modern distributed object technology and emerging telecollaboration tools.

Computer Communication Networks↗
PubMed1995

Natural killer cell ontogeny in the athymic rat. Relationship between functional maturation and acquired resistance to E1A oncogene-expressing sarcoma cells.

Newborn nude rats are NK cell deficient and highly susceptible to tumor induction by NK-susceptible, E1A oncogene-expressing, BHK-21 sarcoma cells, whereas adults have normal NK activity and are tumor resistant. This model of NK cell-related tumor rejection was used to characterize age-related functional maturation of NK cells during nude rat ontogeny. Small numbers of cytolytic incompetent, NKR-P1+ cells were detected in the spleens of newborns. During the first month of life, there was an age-related increase in the numbers of splenic NK cells, followed by a stepwise maturation in their cytolytic competence. Three functional stages in NK cell cytolytic activity were apparent. A nonlytic newborn stage was followed by a transitional stage, during which absent or relatively weak spontaneous cytolytic activity was augmented by prolonged NK cell exposure to susceptible target cells. In the final stage, both spontaneous and augmented cytolytic activity increased toward the adult level that was attained by 4 wk of age. The data suggest the existence of a transient stage in NK cell ontogeny when triggering through the NKR-P1 molecule is functionally immature, and confirm the importance of a cytolytic competent, NK cell response for nude rat rejection of E1A oncogene-expressing tumor cells.

Adenovirus E1A Proteins↗
PubMed1995

Distance constraints and stereospecific alignment requirements characteristic of p53 DNA-binding consensus sequence homologies.

We present evidence in favor of the position that some mutant p53 proteins retain the ability to trans-activate downstream genes through p53 DNA-binding consensus sequence (CS) homologies. We tested one cell line possessing high levels of mutant p53 and found that this mutant p53 is highly active in trans-activating one CS homology, moderately active in trans-activating a second sequence and inactive in modulating a third sequence. We tested a second cell line, also possessing high levels of mutant p53 and found the same pattern of activation. In addition we find that inter-motif distance [represented by N in RRRCWWGYYY(N)RRRCWWGYYY] is very important in determining the relative binding affinity of a given CS homology for wild-type or mutant p53. Our studies suggest that stereospecific alignment of the DNA-binding motifs within the CS may favor binding of wild-type p53 while misalignment may favor binding of mutant p53. Furthermore, we find that the maximum distances at which p53 DNA-binding CS homologies are functionally active vary for different sequences. Introduction of as few as 200 bp between one CS homology and the downstream TATA box can eliminate a 45-fold p53-mediated transactivation. We present evidence that the composition of the DNA which flanks a p53 DNA-binding consensus sequence may also modulate trans-activation.

Amino Acid Sequence↗
PubMed1995

The effects of end point overdispersions on the validity of single-dose tumorigenicity assays.

Overdispersion can be found in tumor incidence and tumor latency end point values obtained by the conventional assays that are being used to assess the tumorigenicity of neoplastic cells growing in tissue culture. Failure to account for such wide variations in end point data can lead to incorrect assessments of the neoplastic cell tumorigenic phenotype and misinterpretations of data relating genetic functions to tumor-forming capacity. This problem suggests the need for more detailed analyses of the relationships that exist between tumor cell dose and the parameters being used to measure tumorigenicity.

Animals↗
PubMed1995

E1A gene expression induces susceptibility to killing by NK cells following immortalization but not adenovirus infection of human cells.

Adenovirus (Ad) infection and E1A transfection were used to model changes in susceptibility to NK cell killing caused by transient vs stable E1A expression in human cells. Only stably transfected target cells exhibited cytolytic susceptibility, despite expression of equivalent levels of E1A proteins in Ad-infected targets. The inability of E1A gene products to induce cytolytic susceptibility during infection was not explained by an inhibitory effect of viral infection on otherwise susceptible target cells or by viral gene effects on class I MHC antigen expression on target cells. This differential effect of E1A expression on the cytolytic phenotypes of infected and stably transfected human cells suggests that human NK cells provide an effective immunologic barrier against the in vivo survival and neoplastic progression of E1A-immortalized cells that may emerge from the reservoir of persistently infected cells in the human host.

Adenovirus E1A Proteins↗
PubMed1995

Relationship of anatomic disease to appropriateness ratings of coronary angiography.

BACKGROUND: At Harvard Community Health Plan (HCHP), Brookline, Mass, a mixed-model health maintenance organization (HMO), coronary angiography is performed at numerous community and tertiary-level teaching hospitals. OBJECTIVE: To determine the appropriateness of coronary angiography within HCHP according to RAND (1992) criteria and to examine the relationship between the appropriateness rating and (1) the clinical indication for catheterization and (2) the extent of anatomic disease. METHOD: A retrospective, randomized hospital medical record review of 292 patients enrolled in HCHP who underwent coronary angiography in 1992, stratified by four distinct HCHP subgroups. RESULTS: Of the coronary angiographies reviewed, 78% were rated appropriate, 16% uncertain, and only 6% inappropriate across the entire sample. Ratings were comparable in all subdivisions of HCHP despite an incidence rate of catheterization in one of the three HMO divisions that was 60% and 40% higher than in the other two divisions. The lowest appropriateness ratings were for Asymptomatic patients (43%) and those with Chest Pain of Uncertain Origin (35%) (capital letters refer to the RAND clinical indication criteria mentioned above). A rating of necessity was not a better discriminator of anatomic disease than a rating of appropriateness alone: 82% and 84%, respectively, were found to have disease by angiography. CONCLUSION: The low HCHP rate of inappropriateness for coronary angiography is comparable with the RAND 1992 New York State data. This finding, coupled with marked differences in the incidence rate of this procedure among the HCHP divisions, is consistent with either major differences in the sickness of the HMO's sub-populations or, more likely, a lack of specificity of the RAND criteria for coronary angiography.

Aged↗
PubMed1995

Retroviral suicide vector does not inhibit neointimal growth in a porcine coronary model of restenosis.

We attempted to attenuate neointimal formation following vascular injury using a retroviral suicide vector. Epicardial coronary arteries of adult miniature swine were injured by deployment of oversized tantalum stents. One week later, injured segments were exposed to packaged retroviral constructs with or without the herpes simplex virus thymidine kinase gene. Ganciclovir treatments were initiated 48 hours later in both control and experimental swine and continued for two weeks. Four weeks following vascular injury, both control and experimental arteries were harvested and histologically prepared for image analysis. Despite adequate marker gene expression, there was no significant difference in the neointimal area or neointimal/media ratio between control and experimental groups. While the HSVtk ganciclovir system attenuates cell proliferation in other systems, retroviral vector targeting of vascular smooth muscle cells for elimination may be too inefficient to prevent restenosis following angioplasty.

Animals↗
PubMed1995

Identification and antisense inhibition of a renin-angiotensin system in transgenic cardiomyocytes.

Cardiac myocytes (AT-1 cells) derived from heart tumors of mice transgenic for an atrial natriuretic factor promoter, SV40 large T-antigen DNA transgene, demonstrate properties consistent with normal cardiac myocytes but retain the capacity to proliferate in culture. We studied the renin-angiotensin system (RAS) and related growth regulation of these cells because AT-1 cells (or transgenically similar cells) may be useful to repair injured myocardium. This study reveals two separate and distinct findings: 1) AT-1 cells proliferate or hypertrophy in response to angiotensin II (ANG II), depending on their competence to proceed through the cell cycle; and 2) AT-1 cells possess components of a RAS, and angiotensinogen antisense experiments suggest that the RAS is functional in these cells. Specifically, AT-1 cells proliferate in response to ANG II in low-serum medium but hypertrophy in response to ANG II when first treated with mitomycin C (at a concentration that inhibits DNA replication but is not cytotoxic). The ANG II-mediated proliferative and hypertrophic responses are inhibited by DuP 753. In addition, there is a significant increase in the protein-to-DNA ratio of cells, which are proliferation-inhibited in the absence of ANG II treatment (20%, P < 0.05). DuP 753 also inhibits this hypertrophy, suggesting that these cells possess a functional RAS. AT-1 cells contain mRNAs for angiotensin-converting enzyme, renin, angiotensinogen, and the AT1 receptor as determined by sequence analysis of polymerase chain reaction amplification products. Antisense oligonucleotides complementary to the angiotensinogen mRNA specifically inhibit angiotensinogen mRNA accumulation and proliferation of AT-1 cells. In summary, these cells contain a growth-regulating RAS, suggesting that such a system may play a significant role in left ventricular hypertrophy.

Angiotensin II↗
PubMed1993

Prior arterial injury enhances luciferase expression following in vivo gene transfer.

We determined the time course of gene expression following DNA/Lipofectin transfection of normal or previously injured arterial segments using direct intraluminal infusion following surgical exposure. Constructs possessing the firefly luciferase cDNA regulated by Simian virus 40, Rous sarcoma virus, or alpha-actin promoter were incubated together with Lipofectin for 30 minutes. Arterial segments were assayed for luciferase activity following harvest at 2-21 days. Without prior injury, luciferase activity was only 2.5-fold greater than background two days following gene transfer. Arterial injury three days before gene transfer resulted in luciferase activity 12.5-fold over background levels. This observation has clinical implications with regard to gene therapy following angioplasty, a procedure that is associated with endothelial cell denudation and smooth muscle cell proliferation. Maintenance of gene expression for several days could ameliorate the early smooth muscle migration and proliferation following arterial injury.

Actins↗
PubMed1993

Endogenous expression of E1A in human cells enhances the effect of adenovirus E3 on class I major histocompatibility complex antigen expression.

Group C human adenovirus (Ad) serotypes (e.g., Ad type 2 [Ad2] and Ad5) cause persistent infections in humans. One explanation for Ad persistence is an ineffective cytotoxic T-lymphocyte response due to diminished cell surface expression of class I major histocompatibility antigen (MHC Ag) on Ad-infected cells, an effect mediated by the Ad E3 19-kDa glycoprotein (E3 effect). However, we previously reported that, except for the Ad5 E1-transformed human cell line 293, a variety of human lymphoid, epithelial, and fibroblastic cells are resistant to the E3 effect during Ad5 infection (J. M. Routes and J. L. Cook, J. Immunol. 144:2763-2770, 1990). The present study tested the hypothesis that endogenous expression of E1A proteins in 293 cells sensitizes cells to this E3 effect, resulting in an enhanced downregulation of surface class I MHC Ag expression following Ad5 infection. Human epithelial and fibroblastic cells expressing E1A gene products for at least 72 h exhibited an enhanced E3 effect following Ad5 infection that was independent of baseline levels of surface class I MHC Ag expression and of E1A induction of E3 19-kDa glycoprotein expression. There was a direct correlation between the level of endogenous E1A expressed and the magnitude of the E3 effect. We postulate that the in vivo existence of cells stably expressing either E1A proteins or E1A-like activities in the microenvironment of Ad5 infection provides a reservoir of Ad-infected cells that is relatively protected from the virus-specific cytotoxic T-lymphocyte response, thereby favoring Ad persistence in humans.

Adenovirus E1A Proteins↗
PubMed1993

E1A oncogene expression level in sarcoma cells: an independent determinant of cytolytic susceptibility and tumor rejection.

Ad2/5 E1A oncogene expression induces cytolytic susceptibility of rodent cells to natural killer lymphocytes. To determine whether the requisite thresholds of E1A oncoprotein expression differ for induction of cytolytic susceptibility as compared with other E1A-related activities, sarcoma cells expressing low or normal levels of E1A oncoproteins were compared for differences in morphological transformation, transactivation of viral genes, cytolytic susceptibility and tumorigenicity. Low-level E1A expression transformed sarcoma cells and transactivated the Ad5 E2A gene but did not induce the increased cytolytic susceptibility observed with normal levels of E1A expression. Furthermore, low-level E1A expressers retained the tumorigenicity of parental cells, whereas normal-level expressers were non-tumorigenic in hosts with intact natural killer (NK)-cell responses. In contrast to E1A, E1B oncogene expression caused no changes in morphological, cytolytic or tumorigenic phenotypes in these sarcoma cells. These data define an expression threshold for E1A-induced cytolytic susceptibility and associated NK-cell-dependent tumor rejection. The results suggest that the cellular mechanisms involved in E1A induction of cytolytic susceptibility differ from those involved in E1A-mediated cellular transformation and viral gene transactivation.

Adenovirus E1A Proteins↗
PubMed1992

Regulation of rodent myelin proteolipid protein gene expression.

The regulation of rodent proteolipid protein (PLP) gene expression was studied during rat development and in cultured cells. Nuclear run-on assays demonstrate a strong transcriptional component associated with the developmental regulation of the PLP mRNA. Transcription rates of the PLP and MBP genes parallel their respective steady-state mRNA levels throughout rat brain development. In addition, a moderate 25-h half-life was measured for PLP mRNA in 37-day-old cultured oligodendrocytes, suggesting that regulation of PLP expression occurs predominantly at the transcriptional level. Finally, 5400 and 1400 bp of mouse PLP 5'-flanking sequence demonstrate transcriptional activity 13-fold and 5-fold above background, respectively, in hamster glial cells. Far upstream elements are clearly involved in transcription of the PLP gene. The 5400 bp sequence demonstrates no more activity than the 1400 bp in a mouse hepatoma cell line suggesting that elements involved in the glial cell-specific expression of PLP lie between 1400 and 5400 bp upstream of the gene.

Animals↗
PubMed1992

The use of antisense oligonucleotides to establish autocrine angiotensin growth effects in human neuroblastoma and mesangial cells.

Local renin-angiotensin systems (RAS) exist in many cell types, and angiotensin II (AII) has growth regulatory effects in some tissues. We demonstrated the presence of angiotensinogen (ANG) mRNA in cultured human mesangial cells (MC) and SHSY-5Y human neuroblastoma cells using reverse transcription and the polymerase chain reaction (RT/PCR) followed by hybridization to a human ANG-specific oligonucleotide probe. We speculated, therefore, that AII might act in an autocrine or paracrine fashion to regulate the growth of mesangial cells and neuroblastoma cells. Sense and antisense oligonucleotides were next synthesized complementary to the ANG transcription start site. Antisense but not sense oligonucleotides decreased [3H]thymidine incorporation into DNA by both MC and neuroblastoma cells. Growth of antisense oligonucleotide-treated cells was restored to control levels by the addition of AII but not by the addition of basic fibroblast growth factor. Neither oligonucleotide affected [3H]thymidine incorporation in mouse L929 cells. These data indicate that locally produced AII can act in an autocrine or paracrine fashion to alter the growth of human mesangial and neuroblastoma cells. Therefore, they suggest a role for local RAS in the pathogenesis of growth abnormalities in the cardiovascular system as well as in some forms of malignancy.

Angiotensin II↗
PubMed1992

Aspergillosis of the prostate associated with an indwelling bladder catheter: case report and review.

Fungal prostatitis is an uncommon disease whose presentation is usually similar to that of benign prostatic hypertrophy and is usually diagnosed unexpectedly after surgery for relief of prostatic obstruction. To our knowledge, we report the first case of prostatic aspergillosis that developed as a complication of indwelling bladder catheterization. This unusual manifestation of invasive aspergillosis occurred in a patient at risk for invasive fungal disease because of chronic corticosteroid use and recent administration of broad-spectrum antibiotics. The previously reported cases of prostatic aspergillosis are reviewed.

Aspergillosis↗