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Biomedical subjects

P Kelley

Publications and source records attributed to P Kelley.

17 recordsLinked to original sources
PubMed2001

Exogenously regulated stem cell-mediated gene therapy for bone regeneration.

Regulated expression of transgene production and function is of great importance for gene therapy. Such regulation can potentially be used to monitor and control complex biological processes. We report here a regulated stem cell-based system for controlling bone regeneration, utilizing genetically engineered mesenchymal stem cells (MSCs) harboring a tetracycline-regulated expression vector encoding the osteogenic growth factor human BMP-2. We show that doxycycline (a tetracycline analogue) is able to control hBMP-2 expression and thus control MSC osteogenic differentiation both in vitro and in vivo. Following in vivo transplantation of genetically engineered MSCs, doxycycline administration controlled both bone formation and bone regeneration. Moreover, our findings showed increased angiogenesis accompanied by bone formation whenever genetically engineered MSCs were induced to express hBMP-2 in vivo. Thus, our results demonstrate that regulated gene expression in mesenchymal stem cells can be used as a means to control bone healing.

Animals↗
PubMed1997

Coping with chronic pain: assessing narrative approaches.

Individuals suffering from chronic pain are of concern to social workers because such pain disrupts job, family, and overall social functioning and can lead to depression, excessive health concerns, and withdrawal from activities. This article discusses a project developed to gain understanding of the experiences of people suffering from fibromyalgia, a chronic pain condition with no visible symptoms, and to test the use of narrative approaches in group work with this population. The study used a qualitative ethnographic approach as the primary method and also used some quantitative measures to assess the usefulness of the approach. Both qualitative and quantitative findings suggest that narrative approaches helped participants find their own strengths and means of coping and helped them find identities other than as patients.

Adaptation, Psychological↗
PubMed1995

Sexual health education interventions for young people: a methodological review.

OBJECTIVES: To locate reports of sexual health education interventions for young people, assess the methodological quality of evaluations, identify the subgroup with a methodologically sound design, and assess the evidence with respect to the effectiveness of different approaches to promoting young people's sexual health. DESIGN: Survey of reports in English by means of electronic databases and hand searches for relevant studies conducted in the developed world since 1982. Papers were reviewed for eight methodological qualities. The evidence on effectiveness generated by studies meeting four core criteria was assessed. Judgments on effectiveness by reviewers and authors were compared. PAPERS: 270 papers reporting sexual health interventions. MAIN OUTCOME MEASURE: The methodological quality of evaluations. RESULTS: 73 reports of evaluations of sexual health interventions examining the effectiveness of these interventions in changing knowledge, attitudes, or behavioural outcomes were identified, of which 65 were separate outcome evaluations. Of these studies, 45 (69%) lacked random control groups, 44 (68%) failed to present preintervention and 38 (59%) postintervention data, and 26 (40%) omitted to discuss the relevance of loss of data caused by drop outs. Only 12 (18%) of the 65 outcome evaluations were judged to be methodologically sound. Academic reviewers were more likely than authors to judge studies as unclear because of design faults. Only two of the sound evaluations recorded interventions which were effective in showing an impact on young people's sexual behaviour. CONCLUSIONS: The design of evaluations in sexual health intervention needs to be improved so that reliable evidence of the effectiveness of different approaches to promoting young people's sexual health may be generated.

Adolescent↗
PubMed1989

Identification of negative and positive regulatory elements in the human renin gene.

Renin gene expression is tissue-specific and under complex hormonal control. To investigate which DNA elements are involved in the control of human renin gene expression, we performed transient DNA transfer experiments with renin-chloramphenicol acetyltransferase fusions. We have mapped a complex arrangement of positive and negative control sequences in the 5' flanking region of the human renin gene. One positive control element is active in either orientation and defines a renin gene enhancer. The negative element is also active in either orientation and defines a renin gene silencer. Mapping in the same region as the silencer is a cAMP-responsive element, a sequence conserved in mouse, rat, and human renin genes.

Animals↗
PubMed1988

Functional human renin promoter in transfected cells: evidence for cell-specific expression.

Expression of the human renin gene is regulated in a tissue-specific manner, but study of this regulation has been limited by a lack of suitable cell lines that simulate endogenous control. In order to characterize the regulation of renin gene expression, the 5' flanking region (892 base pairs) from the human renin gene was linked to the chloramphenicol acetyltransferase gene and was introduced into multiple human cell lines by calcium phosphate precipitation or electroporation methods to assess transcriptional control. The human renin promoter was active when transfected into cultured human choriocarcinoma cells (JEG-3) and rat vascular smooth muscle cells, but it was not active in many other cloned cell types. These results suggest that selective cell lines contain the specific trans-acting factors necessary for human renin gene expression, and support the concept of cell-specific expression of this gene.

Cell Differentiation↗
PubMed1988

Abnormalities of the human growth hormone gene and protooncogenes in some human pituitary adenomas.

Hypersecretion of human GH (hGH) or PRL by human pituitary adenomas is not under normal homeostatic control despite normal receptor function mediating the regulatory effects of hypothalamic peptides for these trophic hormones. This implies that the defects underlying hormonal hypersecretion may not reside at the plasma membrane of the adenoma cell; instead, dysregulation may reside at the hormone gene level. To investigate this, genomic DNA derived from a prolactinoma and a hGH-secreting adenoma were digested with the restriction endonuclease EcoRI and the methylation sensitive restriction endonuclease HpaII and hybridized with the 32P-labeled genomic hGH (2.6 kilobase) probe. Our data revealed hypomethylation of genes of the hGH family (hGH and chorionic somatomammotropin) in the absence of gross abnormalities such as gene translocation. In a similar analysis using a 32P-labeled probe consisting of the EcoRI-BamHI (500 base pair) fragment in the 5'-flanking region upstream of the first exon of the hGH gene, hypomethylation of this specific site of the hGH genes was observed. These results are consistent with the concept that hypomethylation of genes is involved in gene expression. At the same time, protooncogene abnormalities in these adenomas were investigated to delineate any genetic basis for their neoplastic growth. Genomic DNA of adenomas were subjected to Southern blotting analysis using a panel of protooncogene probes. Amplification of the v-fos gene was observed in one prolactinoma. The significance of this observation is discussed.

Adenoma↗
PubMed1987

Tumorigenicity in the nude mouse of cocultures derived from two nontumorigenic cell types, human pituitary adenomas and mouse C3H 10T1/2 fibroblasts.

Human pituitary adenoma tissues were not tumorigenic in the hormonally manipulated nude mouse. Mouse fibroblast cells (C3H 10T1/2) also did not form tumors when inoculated alone into nude mice. When these two tissues were cocultured and coinoculated into nude mice however, the majority of inocula developed progressively enlarging tumors which could be established in tissue culture and passaged through the nude mouse. These tumors were sarcomatous histologically and thus did not resemble any human pituitary adenoma tissue injected. In order to detect any human cells in these tumors, tumor genomic DNA was subjected to Southern analysis using human repetitive Alu and HGH DNA sequence probes. Southern blot analysis of the nude mouse derived tumor genomic DNA revealed no sizeable human DNA in the mouse tumor cell genome indicating the absence of significant numbers of human cells in the tumors or the transfer of human DNA to the mouse cells. The tumors therefore arose from transformed C3H 10T1/2 cells after coculture with the human pituitary adenoma cells. These results implied that the tumorigenic transformation of susceptible C3H 10T1/2 cells in the cocultures occurred as a result of the secretion by the adenoma cells of transforming substances in the culture media or the induction of tumorigenicity through direct cell-cell contact between the two cell types.

Adenoma↗
PubMed1984

Effective and fibrin-specific clot lysis by a zymogen precursor form of urokinase (pro-urokinase). A study in vitro and in two animal species.

A single-chain 55,000-mol wt form of urokinase (UK), similar to that previously isolated from urine, was purified from a transformed kidney cell culture medium and characterized; and its fibrinolytic properties were evaluated. The preparation immunoprecipitated with UK antiserum, had a low intrinsic amidolytic activity that was 0.1% of its active derivative, and resisted diisopropyl fluorophosphate treatment and inactivation by plasma inhibitors. The single-chain UK was therefore designated pro-UK. In the presence of plasmin and during clot lysis, activation by conversion to two-chain, 55,000-mol wt UK (TC-UK) was demonstrated. This did not occur during blood clotting nor on incubation with purified thrombin. Clot lysis in plasma consistently occurred in 2-5 h with 50-100 IU per ml of pro-UK, whereas comparable lysis was inconsistently achieved by 500-1,000 IU of UK. Pro-UK, in sharp contrast to UK, caused no fibrinogen degradation at fibrinolytic concentrations. In the absence of a clot, pro-UK in plasma was stable for more than 2 d. When a clot was added after incubation (37 degrees C) for 50 h, activation to full lytic activity took place. The findings in vivo were comparable but the rapid clearance of pro-UK required that it be given by a constant infusion despite its plasma stability. In rabbits, a UK-resistant species, pro-UK was significantly (P less than 0.001) more efficacious than TC-UK but neither induced significant fibrinogen degradation. In dogs, a more sensitive species, the high specificity of thrombolysis by pro-UK contrasted with the defibrinogenation and uncontrollable bleeding that accompanied thrombolysis by UK. It was concluded that clot lysis by pro-UK is more effective and specific than UK. The advantage of pro-UK is in the limitation of its activation to the site of a clot. This can be explained by an activation mechanism that is dependent, under physiological conditions, on fibrin-stabilized plasmin.

Animals↗
PubMed1972

Mode of action of phleomycin on Bacillus subtilis.

Phleomycin appears to act on the cell wall and membrane to induce the release of membrane-associated deoxyribonucleic acid (DNA) and the degradation of the DNA. Degradation occurs in a series of energy-requiring endonuclease and exonuclease reactions. These produce, first, single-strand breaks, then double-strand breaks, and finally almost complete solubilization of the cellular DNA. The in vivo inhibition of DNA synthesis by phleomycin is probably a secondary effect caused by the destruction of template DNA.

Antibiotics, Antineoplastic↗
PubMedDate not supplied

Engineered pluripotent mesenchymal cells integrate and differentiate in regenerating bone: a novel cell-mediated gene therapy.

BACKGROUND: Among the approximately 6.5 million fractures suffered in the United States every year, about 15% are difficult to heal. As yet, for most of these difficult cases there is no effective therapy. We have developed a mouse radial segmental defect as a model experimental system for testing the capacity of Genetically Engineered Pluripotent Mesenchymal Cells (GEPMC, C3H10T1/2 clone expressing rhBMP-2), for gene delivery, engraftment, and induction of bone growth in regenerating bone. METHODS: Transfected GEPMC expressing rhBMP-2 were further infected with a vector carrying the lacZ gene, that encodes for beta-galactosidase (beta-gal). In vitro levels of rhBMP-2 expression and function were confirmed by immunohistochemistry, and bioassay. Differentiation was assayed using alkaline phosphatase staining. GEPMC were transplanted in vivo into a radial segmental defect. The main control groups included lacZ clones of WT-C3H10T1/2-LacZ, and CHO-rhBMP-2 cells. New bone formation was measured quantitatively via fluorescent labeling, X-ray analysis and histomorphometry. Engrafted mesenchymal cells were localized in vivo by beta-gal expression, and double immunofluorescence. RESULTS: In vitro, GEPMC expressed rhBMP-2, beta-gal and spontaneously differentiated into osteogenic cells expressing alkaline phosphatase. Detection of transplanted cells revealed engrafted cells that had differentiated into osteoblasts and co-expressed beta-gal and rhBMP-2. Analysis of new bone formation revealed that at four to eight week post-transplantation, GEPMS significantly enhanced segmental defect repair. CONCLUSIONS: Our study shows that cell-mediated gene transfer can be utilized for growth factor delivery to signaling receptors of transplanted cells (autocrine effect) and host mesenchymal cells (paracrine effect) suggesting the ability of GEPMC to engraft, differentiate, and stimulate bone growth. We suggest that our approach should lead to the designing of mesenchymal stem cell based gene therapy strategies for bone lesions as well as other tissues.

Animals↗