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A Berk

Publications and source records attributed to A Berk.

17 recordsLinked to original sources
PubMed2003

Prostaglandin E2 induces upregulation of Na+ transport across Xenopus lung epithelium.

The apical mucus on pulmonary epithelia is not only critical for physiological functions such as gas exchange or inflammatory processes, but also contains surfactants and multiple molecules that mediate cellular responses. A tight control of transepithelial ion transport maintains viscosity of this layer and, e.g., the amiloride-sensitive sodium channels (ENaCs) in lung epithelia of vertebrates are the most important regulatory sites for transcellular sodium uptake. Dysfunction of this sodium transport results in reduced liquid absorption and causes massive problems with gas exchange. We used dissected lungs of Xenopus laevis in Ussing chambers to investigate the influence of prostaglandin E2 (PGE2) on the regulation of short-circuit current (ISC) and amiloride-sensitive sodium absorption (Iami). Apical application of PGE2 (1 microM) increased ISC by 38% and Iami by approximately 60%. In contrast, a different prostaglandin, PGI2, neither affected ISC nor Iami. Forskolin increased current to a similar magnitude and preincubation of the lung with an RP-isomer of cyclic AMP, an inhibitor of protein kinase A (PKA), abolished the effects of both PGE2 and forskolin. Transepithelial Na+ uptake was also upregulated by the prostaglandin receptor agonists misoprostol and sulprostone. The Iami in Xenopus oocytes that heterologously expressed ENaCs was not affected by PGE2.

Animals↗
PubMed2002

Investigations on genetically modified maize (Bt-maize) in pig nutrition: chemical composition and nutritional evaluation.

The objective of the present study was to determine the composition and the nutritional value of parental and transgenic maize seeds fed to pigs. The parental maize line was genetically modified to incorporate a gene from Bacillus thuringiensis (Bt) expressing a toxin against the European corn borer (Ostrinia nubilalis). Both (parental and transgenic) maize lines were analyzed for crude nutrients, starch, sugar, non-starch polysaccharides (NSP), amino acids, fatty acids, as well as for selected minerals. Furthermore, four complete diets were mixed and were analyzed for the same nutrients and some selected ingredients. The diets contained 70% maize to attain a high effect level. To evaluate the feeding value of one variety of genetically modified maize (transgenic) compared to the feeding value of the unmodified maize (parental) line, a balance study with twelve pigs was designed. Three collecting periods were used for each maize line each with six animals. The collected faeces were analyzed for crude nutrients. All measured parameters were virtually the same (e.g. crude protein 11.59% vs. 11.06% in DM), especially the digestibility of crude protein (85.8 +/- 2.3% vs. 86.1 +/- 1.8%), the amount of nitrogen-free-extract (92.8 +/- 0.6% vs. 93.2 +/- 0.6%) and the metabolizable energy (15.7 +/- 0.2% vs. 15.8 +/- 0.2% MJ/kg DM) for both maize lines. Compared to the parental line, the chemical composition and digestibility of crude nutrients and energy content were not significantly affected by the genetic modification of maize. Therefore, from the view of a nutritional assessment, the genetically modified maize can be regarded as substantially equivalent to the parental maize line.

Animal Feed↗
PubMed2002

Investigations on genetically modified maize (Bt-maize) in pig nutrition: fattening performance and slaughtering results.

A grower finisher performance trial with forty-eight pigs was designed to compare the growth performance of pigs fed diets containing either genetically modified (GM) Bt-maize (NX6262) or its parental maize (Prelude) line. During the experiment, the pigs were fed with a grower and a finisher diet both containing 70% maize investigated in a previously study which showed that they contained similar ME values and digestibility of crude nutrients. The pigs with an initial live weight of 23.9 +/- 3.0 kg were allotted to single boxes. During a 91 days growing period the pigs of both groups recorded equal performance in daily weight gain (AW) 815 +/- 93 vs. 804 +/- 64 g/d depending on equal amounts of feed intake 1.95 +/- 0.15 vs. 1.94 +/- 0.15 kg/d (parental vs. transgenic). The results confirm equal performance among growing-finishing pigs fed parental or genetically modified maize containing diets. For slaughtering the pigs were divided into 4 groups with a different duration of the finishing period. After slaughtering the carcass characteristic were registered.

Animal Feed↗
PubMed2001

Degradation of phytate in the gut of pigs--pathway of gastro-intestinal inositol phosphate hydrolysis and enzymes involved.

The present study gives an overview on the whole mechanism of phytate degradation in the gut and the enzymes involved. Based on the similarity of the human and pigs gut, the study was carried out in pigs as model for humans. To differentiate between intrinsic feed phytases and endogenous phytases hydrolysing phytate in the gut, two diets, one high (control diet) and the other one very low in intrinsic feed phytases (phytase inactivated diet) were applied. In the chyme of stomach, small intestine and colon inositol phosphate isomers and activities of phytases and alkaline phosphatases were determined. In parallel total tract phytate degradation and apparent phosphorus digestibility were assessed. In the stomach chyme of pigs fed the control diet, comparable high phytase activity and strong phytate degradation were observed. The predominant phytate hydrolysis products were inositol phosphates, typically formed by plant phytases. For the phytase inactivated diet, comparable very low phytase activity and almost no phytate degradation in the stomach were determined. In the small intestine and colon, high activity of alkaline phosphatases and low activity of phytases were observed, irrespective of the diet fed. In the colon, stronger phytate degradation for the phytase inactivated diet than for the control diet was detected. Phytate degradation throughout the whole gut was nearly complete and very similar for both diets while the apparent availability of total phosphorus was significantly higher for the pigs fed the control diet than the phytase inactivated diet. The pathway of inositol phosphate hydrolysis in the gut has been elucidated.

6-Phytase↗
PubMed1998

Regional gene therapy with a BMP-2-producing murine stromal cell line induces heterotopic and orthotopic bone formation in rodents.

The ability to continuously deliver osteoinductive proteins to a specific anatomic site would facilitate the treatment of fracture nonunions and other clinical problems associated with bone loss. We have developed a murine model of regional gene therapy. A bone-marrow stromal cell line infected with an adenovirus expressing recombinant bone morphogenetic protein-2 cDNA secreted biologically active bone morphogenetic protein-2. These bone morphogenetic protein-2-producing cells were able to induce abundant heterotopic bone formation when implanted into the quadriceps muscle of severe combined immune deficient mice and also successfully healed large segmental femoral defects in nude rats. These studies demonstrate that regional gene therapy with continuous delivery of osteoinductive factors to a specific anatomic site can enhance the formation and repair of bone.

Animals↗
PubMed1998

[Effect of various vitamin E supply sources to fattening pigs on pork and bacon quality depending on time of storage].

99 individually kept, fattening pigs (castrated males) were divided into 3 groups. 33 animals each were supplemented with 0, 0.5 or 1.0 g alpha-tocopheryl acetate per day last 21 days before slaughtering. Samples from blood, liver, bacon, and muscle were taken to determine vitamin E content by HPLC depending on time of storing. TBARS values of muscle and bacon, induction-time of bacon ("Rancimat"), pH, drip loss, and color of muscle were determined as further criterions of quality. The Vitamin E supply increased significantly the vitamin E content of all samples (e.g., serum: 1.5, 2.4, and 2.7 mg/kg; liver: 3.8, 5.6, and 7.0 mg/kg for 0, 0.5, or 1.0 g per animal per day, respectively). Vitamin E content of pork decreased depending on time of storing (3.9, 6.2, and 7.8 mg/kg vers. 1.9, 4.1, and 5.0 mg/kg after 29 weeks of freeze storing). Storing time had no significant influence on vitamin E content of bacon. Vitamin E supply (esp. 1.0 g daily) decreased TBARS values, increased time of induction and improved meat color, but did not influence pH and drip loss of porc significantly.

Animal Feed↗
PubMed1997

Intracoronary gene transfer of immunosuppressive cytokines to cardiac allografts: method and efficacy of adenovirus-mediated transduction.

OBJECTIVE: Allograft-targeted immunosuppressive gene therapy may inhibit recipient immune activation and provide an alternative to systemic immunosuppression. We studied the optimal technique and efficacy of intracoronary gene transfer of viral interleukin-10 and human transforming growth factor-beta 1 in a rabbit model of heterotopic heart transplantation. METHODS: Replication-defective adenoviral vectors were constructed, expressing viral interleukin-10 (AdSvIL10) or transforming growth factor-beta 1 (AdCMVTGF-beta 1). Intracoronary delivery of vectors was accomplished ex vivo by either bolus injection or slow infusion. The allografts were implanted heterotopically in recipient rabbits and collected 4 days after the operation. Vector dose was 4 x 10(9) to 6 x 10(10) pfu/gm of donor heart. Transfer was confirmed by DNA amplification for both genes. Gene product expression in tissue was quantified by immunoassay and visualized by immunohistochemical staining. RESULTS: Allograft viral uptake was only 9.9% +/- 2.4% with bolus injection, but increased to 80.5% +/- 6.8% at 1 ml/min infusion rate (p = 5 x 10(-14)). Uptake ratio was not affected by vector quantity or slower infusion rates. Transforming growth factor-beta 1 was consistently detected in allografts infected with AdCMVTGF-beta 1, but not with control adenovirus or AdSvIL10. Expression was proportional to infused vector quantity and reached 10 ng/gm of allograft at infused 10(10) pfu/gm. Transforming growth factor-beta 1 was also detected in recipient's serum at less than 1 ng/ml. Viral interleukin-10 was detected in minor amounts only (< 1 ng/gm) in allografts infected with AdvIL10 up to 5 x 10(10) pfu/gm. Nevertheless, it was detected in recipient serum at concentrations up to 0.4 ng/ml. CONCLUSIONS: Intracoronary gene transfer of immunosuppressive cytokines to cardiac allografts during cold preservation is feasible. Slow infusion is superior to bolus injection. In vivo effects on allograft rejection remain to be determined.

Adenoviridae↗
PubMed1988

Constraints on spacing between transcription factor binding sites in a simple adenovirus promoter.

The adenovirus 2 E1B transcription unit has an extremely simple promoter consisting of a TATA box and a closely situated GC box. The interaction between the TATA box and the GC box was analyzed using insertion mutations which expand the distance between the two elements. We observed that the E1B promoter has an unusually rigid architecture. When the GC box, which is a binding site for transcription factor Sp1, was separated further from the TATA box than in the wild-type promoter, in vivo transcription quickly diminished to a level comparable to the elimination of the Sp1 site. Yet all the insertion mutants bound Sp1 factor in vitro with an affinity approximately equal to that of the wild-type promoter. From these results, we argue that Sp1 binding alone is not sufficient to stimulate transcription. The increased distance might disrupt direct contacts between Sp1 and transcription factors bound at the TATA box, contacts required for transcription stimulation by Sp1. The insertion mutations do not interfere with the transcription activation process mediated by the adenovirus large E1A protein or the pseudorabies virus immediate early protein.

Adenoviridae↗
PubMed1984

Adenovirus E1A protein activation of an integrated viral gene.

Adenovirus early region 1A (E1A) protein stimulates transcription from five viral promoters during the early phase of infection. This protein also stimulates transcription from non-viral genes which are newly introduced into cells by infection or transfection, but not from the endogenous copies of these non-viral genes. Here we show that E1A protein induces expression of an early adenovirus gene integrated into the chromosomal DNA of stably transformed cells. This induction requires the continuous expression of the same E1A protein which stimulates transcription of newly introduced genes. Thus, although the activity of E1A protein is not highly sequence specific, since it can stimulate transcription from newly introduced non-viral genes, the results reported here indicate that it displays some degree of sequence specificity in that an endogenous adenovirus transcription unit responds differently from most cellular genes.

Adenoviridae↗
PubMed1984

Complete transformation by adenovirus 2 requires both E1A proteins.

Rodent cells transformed by adenovirus 2 (Ad2) express two highly related viral proteins of 289 and 243 amino acids encoded in early region 1A (E1A). Transformation studies were performed with adenovirus mutants that express only one or the other E1A protein. We found that the 289 amino acid protein, which has transcription inducing activity, and the 243 amino acid protein, which has little if any of this activity, were both required to produce the fully transformed phenotype. Expression of either E1A protein induced a partially transformed phenotype. The 243 amino acid protein was particularly important for anchorage independent growth. As found in previous studies with several other E1A mutants, the process of transformation by the mutant that expresses the 243 amino acid protein only was cold-sensitive. While the 289 amino acid protein is the only E1A protein required for efficient viral replication under standard cell culture conditions, the 243 amino acid protein in addition to the 289 amino acid protein was found to be required for efficient viral replication in growth-arrested human cells.

Adenoviruses, Human↗
PubMed1978

The economic cost of illness: fiscal 1975.

In 1963, Rice estimated the costs of illness and then allocated these costs by disease. She and Cooper in 1972 updated the original estimates and developed a more sophisticated methodological approach. This paper updates further the costs of illness to 1975 and presents further methodological changes. Analysis of the direct and indirect costs of illness for 1975 reveals that the upward trend into total costs continued, reaching $264 billion. The indirect costs are loss of earnings due to morbidity or premature mortality estimated at various discount rates allocated into 18 categories by disease. The direct costs include such payments as those made for hospital care, physician services, and drugs which are allocated by disease and unallocated costs such as construction and research. The proportion of total costs due to premature mortality were found to drop slightly from 1972 to 1975, while the morbidity share increased slightly. Direct costs account for approximately the same share of total illness in 1975 as in 1972. The proportion of total costs accounted for by direct costs varies directly with the discount rate selected, with the direct costs accounting for 50 per cent of the total at the 10 per cent discount rates and 37 per cent at 2.5 per cent rate. The proportion due to morbidity costs also varies directly with the discount rate, although the changes are small. There is an inverse relationship between the share for premature mortality costs and discount rate.

Direct Service Costs↗
PubMedDate not supplied

A TATA box implicated in E1A transcriptional activation of a simple adenovirus 2 promoter.

Adenovirus E1A proteins stimulate transcription by RNA polymerases II and III from many promoters. The detailed mechanism of transcriptional activation (transactivation) by E1A proteins remains unclear, but genetic and biochemical results suggest that E1A products might act to stimulate the activity of cellular transcription factors. In this study, a detailed mutational analysis of the adenovirus E1B promoter was undertaken to define the DNA sequences required for proper basal transcription and E1A transactivation. Two key findings emerged: first the E1B promoter is an unusually simple RNA polymerase II promoter requiring only two sequence elements for proper regulation, the TATA box and a binding site for transcription factor Sp1; and second only mutations in the TATA box interfere with E1A-transactivation, suggesting that E1A mediates its effect on this promoter through the TATA-box transcription factor.

Adenovirus Early Proteins↗