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Biomedical subjects

C R Mueller

Publications and source records attributed to C R Mueller.

46 records · Page 3Linked to original sources
PubMed1988

The polyomavirus enhancer comprises multiple functional elements.

The polyomavirus enhancer occupies 244 base pairs within noncoding sequences between the early and late transcription units. To define more precisely the DNA sequences that make up the enhancer, we cloned it together with the viral early promoter upstream of a reporter gene, isolated mutants bearing deletions introduced in vitro in the enhancer, and measured the capacity of the various mutant genomes to express the cat gene after transient transfection into mouse 3T3 cells. Analysis of a large number of deletion mutants revealed that the enhancer is between 102 and 172 base pairs long and can be divided into at least three functional elements. Relative to the entire enhancer, individual elements possessed little or no enhancer activity. However, pairs of elements enhanced transcription to levels much higher than the sum of individual elements approximating the activity of the complete enhancer. These findings support the view that the polyomavirus enhancer is composed of multiple sequence elements that function combinatorily and imply that a measure of cooperation exists in the interaction between cellular protein factors bound to their cognate sites in the enhancer and the transcriptional machinery of the cell.

Animals↗
PubMed1988

Lactational response to soybean meal, heated soybean meal, and extruded soybeans with ruminally protected methionine.

Seventy-three high producing Holstein cows were arranged in a 3 X 2 factorial to evaluate three protein supplements (soybean meal, heat-treated soybean meal, and extruded blend of soybeans and soybean meal) without or with 15 g/head/d of ruminally protected DL-methionine during wk 4 through 16 postpartum. Total mixed diets contained (DM basis) 30% corn silage, 15% alfalfa hay, and 55% of the respective concentrate mix. Milk production was higher when cows were fed either heated soybean product instead of soybean meal. Methionine supplementation increased production when fed with soybean meal (32.2 and 33.8 kg/d) but not when fed with heat-treated soybean meal (34.5 and 33.0 kg/d) or extruded soybeans (36.2 and 34.4 kg/d). Milk fat percentages were lower with extruded soybeans (3.01, 2.93, and 2.66) and were similar without (2.83) or with (2.90) supplemental methionine. Milk protein percentages were highest when fed soybean meal, lowest with extruded soybeans (3.02, 2.92, and 2.87), and higher with supplemental methionine (2.91 and 2.96). Dry matter intake was higher when fed supplemental methionine (20.0 and 21.3 kg/d). Production of milk in early lactation high producing dairy cows was increased by supplementing a soybean meal diet with ruminally protected methionine or by replacing the soybean meal with heat-treated soybean meal, soybeans, or a mixture of the two.

Animal Feed↗
PubMed1987

Protected methionine supplementation with extruded blend of soybeans and soybean meal for dairy cows.

Methionine may be the first amino acid limiting milk production in early lactation cows. To evaluate this further, 23 high producing Holstein cows (9 multiparous and 14 primiparous) were fed an extruded blend of soybeans and soybean meal (40:60) without or with 15 g of added DL-methionine as 50 g of ruminally protected methionine product during wk 4 to 16 postpartum. Cows were fed a 15.8% crude protein total mixed ration consisting of 30% (dry basis) corn silage, 15% alfalfa hay, and 55% concentrate mix. Covariant-adjusted yields of milk (35.3 and 33.9 kg/d) and solids-corrected milk (29.3 and 28.2 kg/d) were lower for cows fed ruminally protected methionine, whereas yields of 4% fat-corrected milk (28.2 and 27.4 kg/d) were similar. Percentages of fat (2.68 and 2.69) and solids-not-fat (8.82 and 8.83) were similar, and percentages of protein (2.86 and 2.90) were higher from cows fed supplemental methionine. Dry matter intakes (20.5 and 21.6 kg/d) were higher for cows fed ruminally protected methionine. Methionine concentrations in arterial and venous serum were elevated slightly by feeding supplemental methionine. Although methionine was still the first-limiting amino acid as calculated by two different methods, supplementation of this diet with ruminally protected methionine did not increase production of early lactation cows.

Animal Feed↗
PubMed1984

Location of sequences in polyomavirus DNA that are required for early gene expression in vivo and in vitro.

To define the DNA sequences required for the expression of the polyomavirus early transcription unit, we cloned part of the viral genome in a plasmid vector, isolated mutants bearing lesions introduced in vitro within DNA sequences upstream of the transcriptional start site, and measured the capacity of these various mutant genomes to transform cells and to function as templates for transcription in vitro by comparison with wild-type DNA. One set of mutants bore 5' unidirectional deletions beginning at position -810 and extending downstream to position +4. Another set of mutants bore 3' undirectional deletions starting at position +4 and progressing upstream to position -311. The last set of mutants bore internal deletions between positions -810 and +4. Analyses of the properties of these mutant DNAs led us to conclude that the region between positions -403 and -311 includes an enhancer of gene expression. Deletion of this area from the viral genome reduced gene expression in vivo to 1 to 2% of wild-type levels, as measured by transformation assays. Moreover, this region increased the frequency of transformation of thymidine kinase-negative Rat-2 cells by the herpes simplex virus thymidine kinase (tk) gene from 5- to 20-fold. This occurred only if the polyomavirus sequences were covalently linked to the tk gene and then occurred independently of their orientation or position relative to the tk gene. A second transcriptional element is located downstream of the enhancer between positions -311 and -213. This element together with the enhancer was sufficient to bring about transformation of Rat-1 cells at nearly wild-type frequencies, and together these elements constitute the minimal sequences required for gene expression in vivo. The sequences making up the second element may be functionally duplicated downstream of position -165 (between positions -165 and -60). This was revealed by the characterization of mutant genomes with deletions between positions -349 and -60. The role of these redundant elements is not known; however, they may be analogous to the 21-base-pair repeats of simian virus 40. Finally, sequences between positions -57 and -1 were required for accurate and efficient transcription in vitro. However, this DNA stretch, which includes the TATA box and major transcriptional start sites, was not absolutely required for gene expression in vivo. We conclude that the polyomavirus promoter comprises multiple functional elements which are distributed across a DNA stretch of about 400 base pairs.

Animals↗
PubMed1983

Polyomavirus origin for DNA replication comprises multiple genetic elements.

To define the minimal cis-acting sequences required for polyomavirus DNA replication (ori), we constructed a number of polyomavirus-plasmid recombinants and measured their replicative capacity after transfection of a permissive mouse cell line capable of providing polyomavirus large T antigen in trans (MOP cells). Recombinant plasmids containing a 251-base-pair fragment of noncoding viral DNA replicate efficiently in MOP cells. Mutational analyses of these viral sequences revealed that they can be physically separated into two genetic elements. One of these elements, termed the core, contains an adenine-thymine-rich area, a 32-base-pair guanine-cytosine-rich palindrome, and a large T antigen binding site, and likely includes the site from which bidirectional DNA replication initiates. The other, termed beta, is located adjacent to the core near the late region and is devoid of outstanding sequence features. Surprisingly, another sequence element named alpha, located adjacent to beta but outside the borders of the 251-base-pair fragment, can functionally substitute for beta. This sequence too contains no readily recognized sequence features and possesses no obvious homology to the beta element. The three elements together occupy a contiguous noncoding stretch of DNA no more than 345 base pairs in length in the order alpha, beta, and core. These results indicate that the polyomavirus origin for DNA replication comprises multiple genetic elements.

Animals↗
PubMed1983

Polyomavirus large T antigen binds independently to multiple, unique regions on the viral genome.

To map the polyomavirus large T antigen binding sites on the viral genome we employed a quantitative immunoassay. Defined, radiolabeled fragments of the viral genome were reacted with crude nuclear extracts prepared from lytically infected mouse 3T6 cells, and the fragments bound by large T antigen were immunoprecipitated with anti-T serum and Formalin-fixed Staphylococcus aureus. The immunoprecipitated DNA was then analyzed by gel electrophoresis and autoradiography. By the use of a variety of restriction endonuclease-generated fragments of wild-type and mutant viral DNAs, the region of high-affinity binding was localized to a 153-base-pair stretch between nucleotides 5292 and 152. At least two independent binding sites lie within this region, one upstream and the other downstream of the Bg/I site at nucleotide 87. One of the binding sites is located within sequences required in cis for DNA replication; the other overlaps the TATA box and cap sites of the early transcription unit. The two sites share a common sequence, A/TGAGGC-N4/5-A/TGAGGC, which may serve as the recognition sequence for large T antigen.

Antigens, Viral, Tumor↗
PubMed1980

Assignment of the gene coding for human catalase to the short arm of chromosome 11.

Human and murine catalases can be separated electrophoretically as single bands of different mobility. In man-mouse somatic cell hybrids, however, detection of human catalase is precluded by the complexity of banding patterns resulting from interference of a catalase-modifying enzyme activity. We have identified human catalase in hybrid clones by Laurel electrophoresis employing a specific anti-human catalase antibody, and by exploiting heat stability differences. Catalase co-segregates with LDH A and is probably located on the short arm of chromosome 11.

Animals↗
PubMedDate not supplied

Phase I-II trial of hyperthermic isolated limb perfusion with cisplatin in the treatment of high risk malignant melanoma of the extremities.

Between 1983 and 1990, 59 patients with malignant melanoma were retrospectively reviewed to assess the safety, efficacy and the maximal tolerated dose of cisplatin used in hyperthermic isolated limb perfusion. The median follow-up was 29 months (range 3-54 months). The local recurrence rate was 12% in Stage I, 33% in Stage II and 30% in Stage III patients. The maximal tolerated dose of cisplatin in hyperthermic isolated limb perfusion was 3.2 mg/kg for forequarter perfusions and 6 mg/kg for hindquarter perfusions based on lean body weight. At these dosages, there is an 8% major complication rate and only one patient experienced long-term sequelae. Hyperthermic isolated limb perfusion using cisplatin in the dosages of 3-6 mg/kg lean body weight is associated with low morbidity and appears to have efficacy comparable to L-phenylalanine mustard for the control of locally recurrent malignant melanoma.

Chemotherapy, Cancer, Regional Perfusion↗
PubMedDate not supplied

Multidisciplinary research of multimodal stimulation of premature infants: an integrated review of the literature.

PURPOSE: To review and integrate current multidisciplinary research literature about multiple sensory stimulation of premature infants. SOURCES: Computer search using CINAHL, MEDLINE, PSYLIT, SOCIAL SCIENCE INDEX and the topics "premature," "infant," "neonate," and "stimulation." Review of the results of the research and integration of findings for nursing. RESULTS: Overall, infants responded positively to the interventions reviewed, including immediate and long-term effects, some up to 2 years. IMPLICATIONS FOR NURSING PRACTICE: Nursing research of multiple sensory stimulation of premature infants can be improved by the use of (a) a theoretical base for research, (b) better descriptions of the infant samples and the environmental context of the research, and (c) individualization of infant stimulation to permit conservation of epigenetic integrity of the infant.

Female↗