SEARCH · Search PubMed

Results for “Library Administration”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67Linked to original sources

PubMed1991

Expression of hepatocyte growth factor mRNA in regenerating rat liver after partial hepatectomy.

Hepatocyte Growth Factor (HGF) is a potent complete mitogen for primary cultures of hepatocytes in vitro. There is strong evidence that this novel growth factor may mediate hepatocyte regeneration after liver damage. We have shown previously that the amount of immunoreactive HGF markedly increases in the serum of rats soon after partial hepatectomy or CCl4 administration. In the present paper, we demonstrate that the level of HGF mRNA in rat liver also dramatically increases from 3 to 6 hours post hepatectomy, peaks at 12 hr and gradually returns to undetectable levels by 72 to 96 hours post hepatectomy. In separate experiments, DNA synthesis (in vivo) was determined in rat liver remnants after partial hepatectomy. DNA synthesis peaked 24 hr after hepatectomy, 12 hr after the peak of HGF mRNA expression. These results suggest that HGF may be one of the major early signals that triggers hepatocyte proliferation during liver regeneration.

Animals↗

PubMed1999

Characterization of the antiapoptotic Bcl-2 family member myeloid cell leukemia-1 (Mcl-1) and the stimulation of its message by gonadotropins in the rat ovary.

The majority of ovarian follicles undergo atresia mediated by apoptosis. Bcl-2-related proteins act as regulators of apoptosis via the formation of dimers with proteins inside and outside the Bcl-2 family. Previous studies have identified BAD as a proapoptotic Bcl-2 family member expressed in the ovary. It is known that BAD phosphorylation induced by survival factors leads to its preferential binding to 14-3-3 and suppression of the death-inducing function of BAD. To identify ovarian binding partners for hypophosphorylated BAD, we performed a yeast two-hybrid screening of a rat ovary complementary DNA library using as bait a mutant BAD incapable of binding to 14-3-3. Screening of yeast transformants yielded positive clones encoding the rat ortholog of Mcl-1 (myeloid cell leukemia-1), an antiapoptotic Bcl-2 protein. Amino acid sequence analysis revealed that rat and human Mcl-1 showed a complete conservation of the Bcl-2 homology domains BH1, BH2, and BH3. In the yeast two-hybrid system, Mcl-1 binds to the hypophosphorylated mutant of BAD and interacts preferentially with different proapoptotic (Bax, Bak, Bok, Bik, and BOD) compared with antiapoptotic Bcl-2 family members (Bcl-2, Bcl-xL, Bcl-w, Bfl-1, CED-9, and BHRF-1). Northern blot hybridization demonstrated expression of Mcl-1 transcripts of 2.3 and 3.7 kb in the ovary and diverse other rat tissues. In immature rats, PMSG treatment led to a transient increase in the 2.3-kb Mcl-1 transcript, peaking at 6 h after injection and returning to baseline levels after 24 h. Moreover, the same transcript was induced in the PMSG-primed preovulatory rat ovary 6 h after the administration of ovulatory doses of either hCG or FSH. In situ hybridization studies revealed that the gonadotropin stimulation of ovarian Mcl-1 message occurs in both granulosa and thecal cells. In conclusion, rat Mcl-1 was identified as an ovarian BAD-interacting protein and the message for the antiapoptotic Mcl-1 protein was induced after treatment with gonadotropins in granulosa and thecal cells of growing follicles.

Amino Acid Sequence↗

PubMed2002

Regulation of IGFBP-5 expression during tumourigenesis and differentiation of oral keratinocytes.

To identify molecular events involved in the pathogenesis of oral squamous cell carcinoma (OSCC), genes differentially expressed in OSCC and non-cancerous matched tissue (NCMT) samples were analysed using a subtractive hybridization strategy. NCMT-enriching clones that have been linked to suppressor pathway in previous studies were subjected to advanced analyses. Complete absence of insulin-like growth factor binding protein-5 (IGFBP-5) expression at both the mRNA and the protein level was identified in nearly all (5/6) OSCC cell lines with the exception of the SCC25 cell line, which exhibited high IGFBP-5 expression. However, this protein is consistently present in cultured normal human oral keratinocytes (NHOKs). Immunohistochemistry revealed moderate to strong cytoplasmic immunoreactivity of IGFBP-5 in the stratum spinosum and stratum granulosum in the vast majority of NCMT samples. A remarkable reduction in IGFBP-5 immunoreactivity was detected in 56% (26/46) of OSCC samples, compared with the corresponding NCMT (p < 0.0001). Induction of differentiation in both NHOKs and SCC25 up-regulated IGFBP-5 expression. Administration of a green tea compound with anti-cancer properties, (-)-epigallocatechin 3-gallate, at a concentration of 5-20 micro g/ml also up-regulated IGFBP-5 expression in NHOKs in a dose-dependent manner. The findings suggest that IGFBP-5 may be an important factor in the differentiation of oral keratinocytes and that down-regulation of IGFBP-5 may be involved in the neoplastic transformation of oral keratinocytes.

Antineoplastic Agents↗

PubMed2003

Systematic review of the evidence regarding potential complications of inhaled corticosteroid use in asthma: collaboration of American College of Chest Physicians, American Academy of Allergy, Asthma, and Immunology, and American College of Allergy, Asthma, and Immunology.

INTRODUCTION: The available clinical guidelines have been successful in improving awareness of the inflammatory nature of asthma and have promoted the use of inhaled corticosteroids (ICSs) to achieve long-term control of symptoms. Because of lingering concerns over the possible adverse consequences of ICS use, an expert panel was convened with a mandate to identify the critical questions that impact decisions regarding the use of ICSs and to evaluate the available evidence with respect to risk. METHODS: A university librarian retrieved citations and abstracts from the MEDLINE and EMBASE databases using a list of National Library of Medicine search terms and key words. Reviewers were asked to systematically abstract relevant information from each of their assigned articles and to list their own clinical or scientific conclusions based on the study results. A predefined grading algorithm was used to calculate a summary quality rating score for the relevant evidence. RESULTS: The results are presented as a series of key questions followed by a summary of the relevant evidence. An evidence grade is assigned, followed by a summary statement reflecting the panel's consensus opinion following review. CONCLUSIONS: The preponderance of evidence supports a conclusion that the proven clinical effectiveness of ICS treatment decidedly outweighs the proven risks.

Administration, Inhalation↗

PubMed2002

Purified phytoestrogens in postmenopausal bone health: is there a role for genistein?

OBJECTIVE: Genistein is the main isoflavone present in soy and the one to which biological action is most often ascribed. There are suggestions that genistein could have a role as an osteoprotective agent. Hence, a review of the evidence has been undertaken. METHODS: MEDLINE (1966-August 2001), Allied Complementary Medicine (1985-2001), the Cochrane Library and the Database of Systematic Reviews (2nd Quarter 2001) were searched using the key words: genistein, osteoporosis, bone, isoflavones. RESULTS: Genistein appears to bind to the estrogen receptor (ER), with greatest affinity to ER beta. In vitro it stimulates protein synthesis in osteoblast cell lines, and in animal studies it appears to be effective in preventing bone loss caused by estrogen deficiency. There are no published human studies using pure genistein. CONCLUSION: Genistein appears to have a stimulatory effect on osteoblasts and, in some animal studies, it has been shown to exert an anabolic effect on bone. If these effects were to be demonstrated in humans, genistein would be a potentially useful oral anabolic agent for the treatment of osteoporosis.

Administration, Oral↗

PubMedDate not supplied

Asthma as an inflammatory disease: implications for management.

BACKGROUND: Eosinophilic inflammation plays a central role in the pathogenesis of asthma. Striking inflammatory changes are present in the airways of patients with all levels of disease severity. The degree of airway inflammation correlates with airway hyperresponsiveness, the primary physiologic abnormality of asthma. Inflammation is typically initiated by immunologic events (including allergy) and is driven by mediators released by various cells of the immune system, particularly eosinophils, monocytes and macrophages, lymphocytes, and mast cells. METHODS: Literature on asthma and the inflammatory response was drawn from recent articles presented and reviewed in journal clubs and from selected articles from the National Library of Medicine. RESULTS AND CONCLUSIONS: The inflammatory process can be divided into six steps: triggering, signaling, migration, inflammatory cell activation, tissue damage, and resolution. Recognition of the importance of inflammation in the pathogenesis of asthma and the progression of the disease has shifted research efforts and the development of new therapeutic agents toward reduction of airway inflammation. Anti-inflammatory therapy, which can be directed against specific steps in the inflammatory process, actually reduces bronchial hyperresponsiveness. Although anti-inflammatory management has assumed a primary role in asthma therapy, short acting beta 2-adrenergic receptor agonists are needed for treatment of acute symptoms, and some patients require regular beta 2-agonist therapy despite apparently adequate anti-inflammatory therapy.

Administration, Inhalation↗

PubMed2003

Recombinant antibodies for cancer diagnosis and therapy.

Recombinant antibodies currently represent over 30% of biopharmaceuticals in clinical trials, highlighted by the recent Food and Drug Administration (FDA) approvals of Zevalin(TM) (ibritumomab-tiuxetan; IDEC Pharmaceuticals, San Dieago, CA, USA) for cancer radioimmunotherapy and Humira(TM) (adalimumab; Abbott Laboratories, IL, USA) for rheumatoid arthritis. Together, these FDA approvals have excited the biotechnology industry, particularly since sales of recombinant antibodies are increasing rapidly to a predicted US dollar 4 billion per annum worldwide in 2003. To date, 10 engineered therapeutic antibodies have gained FDA approval and many others are in Phase III trials. Many recent FDA-approved antibodies are simple molecular designs that have taken 10 years to be developed into effective therapeutic reagents. Emerging new technologies have created a vast range of recombinant, antibody-based reagents, which specifically target clinical biomarkers of disease. Radiolabelling of antibodies has increased their potential for cancer imaging and targeting. Recombinant antibodies have also been reduced in size and rebuilt into multivalent molecules for higher affinity. In addition, antibodies have been fused with many molecules, including toxins, enzymes, drugs and viruses, for prodrug therapy, cancer treatment and gene delivery. Recombinant antibody technology has enabled clever manipulations in the construction of complex in vitro libraries for the selection of high-affinity reagents against refractory targets. Furthermore, innovative affinity maturation methods have been developed which enable rapid selection of extremely high-affinity reagents. This review focuses on developments in the last 12 months and describes the latest developments in the design, production and clinical use of recombinant antibodies for cancer diagnosis and therapy.

Animals↗

PubMed2005

The impact of oral phenylpropanolamine on blood pressure: a meta-analysis and review of the literature.

Oral phenylpropanolamine is commonly used to treat congestion and obesity. Clinicians often wonder what effect it has on blood pressure and whether they are safe in hypertensive patients. The purpose of our systematic review was to assess whether these drugs cause clinically meaningful elevations in pulse or blood pressure. English-language, randomized, placebo-controlled trials of oral phenylpropanolamine in adults with extractable data on pulse or blood pressure were studied. MEDLINE (1966-2003), Embase, the Cochrane library and reviewed article references were used as sources. Systolic (SBP) and diastolic blood pressure (DBP) and heart rate data were extracted. Additional extracted data included demographics, year, study design, study duration, drug dose and frequency, duration of washout and country. Study quality was assessed using the methods of Jadad and data were synthesized using a random effects model using weighted mean differences. In all, 33 trials reporting 48 treatment arms with 2165 patients were included. Phenylpropanolamine increased SBP 5.5 mmHg (95% CI: 3.1-8.0) and DBP 4.1 mmHg (95% CI: 2.2-6.0) with no effect on pulse. Patients with controlled hypertension were not at greater risk of blood pressure elevation. Immediate release preparations had greater effects on blood pressure than sustained release ones. Higher doses and shorter duration use also caused greater increases. Eighteen studies contained at least one treated subjects having blood pressure elevations > or =140/90 mmHg, an increase in SBP > or =15 mmHg or an increase in DBP > or =10 mmHg. In conclusion, phenylpropanolamine caused a small, but significant increase in systolic blood pressure. The effect was more pronounced with shorter-term administration, higher doses of medication and immediate release formulations.

Administration, Oral↗

PubMed2000

Development of a peptide inhibitor of hyaluronan-mediated leukocyte trafficking.

Hyaluronan (HA), a high molecular weight glycosaminoglycan, is expressed abundantly in the extracellular matrix and on cell surfaces. Although HA is known to bind many adhesion molecules, little information has been available with respect to its direct physiological role. In this study, we developed a novel 12-mer (GAHWQFNALTVR) peptide inhibitor of HA, termed "Pep-1," by using phage display technology. Pep-1 showed specific binding to soluble, immobilized, and cell-associated forms of HA, and it inhibited leukocyte adhesion to HA substrates almost completely. Systemic, local, or topical administration of Pep-1 inhibited the expression of contact hypersensitivity responses in mice by blocking skin-directed homing of inflammatory leukocytes. Pep-1 also inhibited the sensitization phase by blocking hapten-triggered migration of Langerhans cells from the epidermis. These observations document that HA plays an essential role in "two-way" trafficking of leukocytes to and from an inflamed tissue, and thus provide technical and conceptual bases for testing the potential efficacy of HA inhibitors (e.g., Pep-1) for inflammatory disorders.

Amino Acid Sequence↗

PubMed2006

[From the Cochrane Library: topical antibiotic treatment is more effective than systemic antibiotic treatment for chronic otitis media with eardrum perforation and purulent discharge].

Chronic suppurative otitis media with underlying persistent eardrum perforation is a common cause of preventable hearing impairment. A Cochrane systematic review compared topical treatment (antibiotics or antiseptics) with systemic antibiotics to identify which is best. Nine randomised controlled trials were included (833 randomised patients; 842 analysed patients or ears). Topical treatment with quinolones was more effective in stopping (purulent) discharge than systemic treatment with quinolones or non-quinolones. No benefit from adding systemic treatment to topical antibiotics was detected. The effects of topical non-quinolone antibiotics or antiseptics were not clear. Little is known about secondary outcomes (prevention of complications, healing the eardrum, and improving hearing) or about the efficacy and safety of topical antibiotics in the long term.

Administration, Topical↗

PubMed1981

[Optimal exchange of resources and the administration of bibliographical services].

It is pointed out in this paper that an optimal exchange of resources requires a maximum availability of materials and services at minimum cost. The author is of the view that each activity of the biomedical information network will have to be subjected to critical scrutiny including a calculation of its costs. The overall plan will determine whether current activities can be maintained or expanded and new activities launched. The primary given to access to materials rather than to their possession is a step toward user-oriented networks, and therefore means that future development will be assessed in relation to the customer. The author is convinced that the recording and analysis of the use actually made of services by the user will generate many of the criteria that will govern some of the most important decisions to be taken in the future in connection with the network.

Information Services↗

PubMed2002

Dimenhydrinate for prophylaxis of postoperative nausea and vomiting: a meta-analysis of randomized controlled trials.

BACKGROUND: Diphenhydramine and its theoclate salt dimenhydrinate are traditional antiemetics still in use. However, so far the quantitative effect of dimenhydrinate in the prophylaxis of postoperative nausea and vomiting (PONV) has not been evaluated systematically. METHODS: Results from randomized controlled trials investigating the efficacy of dimenhydrinate vs. a control to prevent PONV were included in a meta-analysis. Studies were systematically searched through MEDLINE, EMBASE, the Cochrane-Library, manually screening of reference lists of matching review articles and current issues of locally available peer-reviewed anesthesia journals, up to June 2001. The numbers of patients with complete absence of PONV within 6 h and within 48 h after surgery were extracted as the main end point. Pooled relative benefits (RB) and numbers-needed-to-treat (NNT) with their corresponding 95% confidence intervals (CI) were calculated using a random effects model. This quantitative systematic review was performed following the recommendations of the QUORUM statement. In all, 18 trials with 3045 patients were included in the analysis: 1658 patients received a placebo (control) and 1387 patients received dimenhydrinate. RESULTS: The RB to stay completely free of PONV was 1.2 (95% CI: 1.1-1.4) for the early period (NNT = 8; 95% CI: 5-25) and 1.5 (1.3-1.8) for the overall investigated period (NNT = 5; 95% CI: 3-9). CONCLUSION: Dimenhydrinate is a traditional and inexpensive antiemetic with an efficacy that might be considered as clinically relevant. Although in use for a long time, the dose-response, precise estimation of side-effects, optimal time of administration and the benefit of repetitive doses still remain unclear.

Adult↗

PubMed2003

Long-term effects of inhaled corticosteroids on FEV1 in patients with chronic obstructive pulmonary disease. A meta-analysis.

BACKGROUND: There is no consensus on the effectiveness of inhaled corticosteroids for the treatment of chronic obstructive pulmonary disease (COPD). PURPOSE: To evaluate the long-term effects of inhaled corticosteroids on the rate of FEV1 decline in patients with COPD. DATA SOURCES: MEDLINE, EMBASE, CISCOM, and AMED databases and the Cochrane Library (1966 to December 2002), reference lists from identified articles, and consultation with experts. Searches were not limited to the English language. STUDY SELECTION: Randomized, placebo-controlled trials that examined the rate of FEV1 decline as a primary outcome in patients with COPD. DATA EXTRACTION: Two reviewers independently extracted the data by using predetermined criteria. DATA SYNTHESIS: For the six studies that met the inclusion criteria, the summary estimate for the difference in FEV1 decline between the placebo and treatment groups was -5.0 +/- 3.2 mL/y (95% CI, -11.2 to 1.2 mL/y; P = 0.11). CONCLUSIONS: The use of inhaled corticosteroids was not associated with the rate of FEV1 decline in 3571 patients followed for 24 to 54 months.

Administration, Inhalation↗

PubMed2001

Systematic review of patient and nurse attitudes to depot antipsychotic medication.

BACKGROUND: Depot antipsychotic medication is used widely in the treatment and prophylaxis of severe mental illness. AIMS: To review the literature on patient and nurse satisfaction with, and attitudes towards, depots. METHOD: A systematic search of Medline, Embase, PsycINFO, CINAHL and The Cochrane Library was undertaken, along with citation searches. Studies were selected if satisfaction/attitude data were described in the title or abstract and original data were included. Study quality was rated. RESULTS: The search produced 1374 articles; 22 articles met the inclusion criteria, 18 of which were cross-sectional surveys. Of the 12 studies with relevant data, 10 conveyed a positive opinion of depot medication. Five out of six studies comparing depot with oral medication showed patient preference for depot. CONCLUSIONS: High-quality data examining patient and nurse attitudes regarding depot antipsychotics are sparse. What data there are show a positive attitude to depots from patients. Future randomised controlled trials should include satisfaction as an outcome.

Administration, Oral↗

PubMed1999

Tonicity-responsive enhancer binding protein, a rel-like protein that stimulates transcription in response to hypertonicity.

Hypertonicity (most often present as high salinity) is stressful to the cells of virtually all organisms. Cells survive in a hypertonic environment by increasing the transcription of genes whose products catalyze cellular accumulation of compatible osmolytes. In mammals, the kidney medulla is normally hypertonic because of the urinary concentrating mechanism. Cellular accumulation of compatible osmolytes in the renal medulla is catalyzed by the sodium/myo-inositol cotransporter (SMIT), the sodium/chloride/betaine cotransporter, and aldose reductase (synthesis of sorbitol). The importance of compatible osmolytes is underscored by the necrotic injury of the renal medulla and subsequent renal failure that results from the inhibition of SMIT in vivo by administration of a specific inhibitor. Tonicity-responsive enhancers (TonE) play a key role in hypertonicity-induced transcriptional stimulation of SMIT, sodium/chloride/betaine cotransporter, and aldose reductase. We report the cDNA cloning of human TonE binding protein (TonEBP), a transcription factor that stimulates transcription through its binding to TonE sequences via a Rel-like DNA binding domain. Western blot and immunohistochemical analyses of cells cultured in hypertonic medium reveal that exposure to hypertonicity elicits slow activation of TonEBP, which is the result of an increase in TonEBP amount and translocation to the nucleus.

Amino Acid Sequence↗

PubMed2006

[Revista de Saúde Pública: forty years of Brazilian scientific production].

OBJECTIVE: To recognize the characteristics and path taken by the through analysis of the scientific production it has published over the period from 1967 to 2005. METHODS: Scientometric methods were used to analyze reference data on the articles published in the Revista, retrieved from the databases ISI/Thomson Scientific (Web of Science), National Library of Medicine (PubMed) and Scientific Electronic Library Online (SciELO). RESULTS: The Revista is the only Brazilian publication in the field of public health that is indexed by ISI/Thomson Scientific. It is prominent as a medium for publishing Brazilian scientific production in public health and is displaying a geometric increase in publication and citation, with annual rates of 4.4% and 12.7%, respectively. The mean number of authors per paper has risen from 2 to 3.5 over recent years. Although original research articles predominate, the numbers of reviews, multicenter studies, clinical trials and validation studies have been increasing. The number of articles published in foreign languages has also increased, accounting for 13% of the total, and the leading countries originating these are the UK, USA, Argentina and Mexico. The number and diversity of journals citing the Journal has been increasing, many of which are non-Brazilian. Authorship per author shows good fit to Lotka's Law, but the parameters suggest greater concentration and less dispersion than would be expected. Among the fields of interest of published papers, the following topics account for more than 50% of the total volume: infectious-parasitic diseases and vectors; health promotion, policies and administration; and epidemiology, surveillance and disease control. CONCLUSIONS: The Revista shows great dynamism, without signs of abating or reaching a plateau any time soon. There are signs of progressively increasing complexity in the studies published, and more multidisciplinary work. The Revista seems to be widening its outreach and recognition, while remaining faithful to the field of public health in Brazil.

Abstracting and Indexing↗

PubMed2001

In vivo and in vitro effects of ghrelin/motilin-related peptide on growth hormone secretion in the rat.

Ghrelin (Ghr), a 28 amino acid gastric peptide with an n-octanoylation on Ser 3, has recently been identified as an endogenous ligand of the growth hormone secretagogue (GHS) receptor. A cDNA was also isolated from a mouse stomach library encoding a protein named prepromotilin-related peptide (ppMTLRP) which shares sequence similarities with prepromotilin. Mouse and rat ppMTLRP sequences (rGhr) are identical and show 89% identity with human ghrelin (hGhr). By analogy with promotilin, cleavage of proMTLRP into an 18 amino acid endogenous processed peptide can be assumed on the basis of a conserved dibasic motif in position 9-10 of its sequence. In the present work, we compared the GH-releasing activity of rGhr28/MTLRP and of hGhr28/MTRLP with that of a shorter form of the peptide, hGhr18. A short peptide devoid of Ser-3 n-octanoylation hGhr18[-] was also tested. Addition of rGhr28, hGhr28 and hGhr18 stimulated GH release to the same extent from superfused pituitaries. The effect was dose dependent in a 10(-8) to 10(-6) M concentration range. In contrast, hGhr 18[-] was inactive. In freely moving animals, both rGhr28 and hGhr28 (10 microg, i.v.) stimulated GH release, whereas the same dose of hGhr18 or of hGhr18[-] was ineffective. After rGhr28, GH plasma levels increased as early as 5 min after injection and returned to basal values within 40-60 min. Expressed as percent stimulation, administration of rGhr28 was equally effective when injected during troughs or peaks of GH. Plasma concentrations of prolactin, adrenocorticotropin and leptin were not modified. Spontaneous GH secretory episodes were no longer observed within 3 h of rGhr28 treatment, but repeated administration of the secretagogue at 3- to 4-hour intervals resulted in a similar GH response. Activation of somatostatin (SRIH) release by ether stress did not blunt the GH response to rGhr28. This suggests that the secretagogue acts in part by inhibiting endogenous SRIH, as further substantiated by the ability of rGhr28 (10(-6) M), to decrease the amplitude of 25 mM K+-induced SRIH release from perifused hypothalami. In conclusion, (1) n-octanoylation of Ghrs and the shorter form hGhr18 is essential for the direct pituitary GH-releasing effect of this new family of endogenous GHSs; (2) only the longer forms are active in vivo and (3) inhibition of SRIH release appears involved in the mechanism of Ghr action.

Adrenocorticotropic Hormone↗

PubMed1983

Cloning of DNA complementary to cytochrome P-450 induced by pregnenolone-16 alpha-carbonitrile. Characterization of its mRNA, gene, and induction response.

The major form of cytochrome P-450 (P-450PCN) was isolated from rats administered pregnenolone-16 alpha-carbonitrile (PCN). Messenger RNA coding for P-450PCN was enriched by polysome immunoadsorption and utilized to construct a library of cDNA clones in pBR322. P-450PCN clones were isolated from this library by differential colony hybridization using [32P]cDNA probes transcribed from PCN-induced and PCN-induced P-450PCN immunoenriched poly(A) RNA. The P-450PCN clone with the largest cDNA insert (pP450PCN-10) was verified to contain sequences complementary to P-450PCN mRNA by hybrid selection-translation. pP450PCN-10 was composed of approximately 1900 base pairs and had a restriction map that overlapped at least 3 other cDNA clones selected by differential colony hybridization. Denaturing-agarose gel electrophoresis and nitrocellulose blot-hybridization using nick-translated 32P-labeled pP450PCN-10 indicated that pP450PCN mRNA is 2500 +/- 150 nucleotides in length; pP450PCN-10, therefore, represents approximately 76% of its corresponding mRNA sequence. Southern blot analysis of rat DNA using pP450PCN revealed that approximately 50 to 60 kilobases of DNA reacted with the PCN probe, suggesting the P-450PCN gene is either a very large gene or other genomic segments exist that react with the probe, such as pseudogenes or related P-450 genes that share homology. The mechanism of P-450PCN induction was examined by isolating poly(A) RNA at various times after steroid administration and quantitating for P-450PCN mRNA using pP450PCN-10 as a hybridization probe. PCN administration produced a rapid elevation of P-450PCN mRNA which reached maximal levels (7-fold above control) 12 h after administration. In contrast, cytochrome P-450b mRNA, which is readily induced by phenobarbital, was only slightly elevated (approximately 2-fold) after PCN administration.

Animals↗