Search PubMed⌕ Search

Biomedical subjects

J F Miller

Publications and source records attributed to J F Miller.

At least 217 records · Page 12Linked to original sources
PubMed1987

Intensity and energy cost of weighted walking vs. running for men and women.

The energy cost and intensity of exercise performed at 0% grade were determined for walking at 2, 3, and 4 mph, running at 5, 6, and 7 mph, and walking at 2, 3, and 4 mph with ankle and/or hand weights. Subjects were young moderately trained males (4) and females (3). The energy cost per kilogram of body weight was similar between sexes, and data were combined for among-treatment comparisons. Intensity of effort and energy cost per minute and per mile were increased when weight was added during walking and were increased more with hand weights compared with ankle weights regardless of speed. The average increase in O2 uptake (ml X kg-1 X min-1 X 100 g-1 of added wt) was 0.8% for ankle, 1.3% for hand, and 0.9% for ankle and hand weights. Gross energy cost per mile during weighted walking (120-158 kcal/mile) was comparable to and in some cases exceeded that of running which was independent of speed (120-130 kcal/mile). During nonweighted walking, the energy cost (kcal/mile) was significantly greater at 4 mph compared with 2 and 3 mph which did not differ. The intensity of walking at 4 mph with ankle and hand weights was comparable to running at 5 mph.

Adult↗
PubMed1987

Accessory molecules in T lymphocyte activation.

The currently accepted hypothesis used to explain the role of Lyt-2 and L3T4 in T cell activation proposes how these molecules interact with class I and II major histocompatibility complex molecules, respectively, on the antigen-presenting or target cell, to increase the avidity of binding of the antigen-specific T cell receptor. This has been tested using two antigen-specific, class II-restricted T cell clones expressing both Lyt- and L3T4. Inhibition of function was observed only with monoclonal antibody against L3T4, not Lyt-2. One interpretation of these results is that L3T4 and the class II-restricted T cell receptor can physically associate during T cell activation to form a multi-molecular complex from which Lyt-2 is excluded.

Animals↗
PubMed1986

Purification and characterization of a glycogen phosphorylase analog missing the amino-terminal segment.

A glycogen phosphorylase analog missing only the amino-terminal 16 to 18 residues, which include the phosphorylation site, was produced by subtilisin Carlsberg cleavage of phosphorylase b in the presence of caffeine. The analog, named phosphorylase b's, was purified, and its enzymatic properties were compared with those of phosphorylase b. The KM's for glucose 1-phosphate are similar, but phosphorylase b's has a VM 43% higher than that of phosphorylase b. Also, phosphorylase b's is less sensitive to inhibition by glucose 6-phosphate and stimulation by sodium fluoride than is phosphorylase b. The subunit interactions in the two enzyme forms were also compared. The monomer-monomer interactions in phosphorylase b's are weaker than in phosphorylase b, as evidenced by a faster rate of resolution of the coenzyme, pyridoxal phosphate, from phosphorylase b's. The dimer-dimer interactions are also weaker in phosphorylase b's than in phosphorylase b, because phosphorylase b's does not form tetramers or crystals as readily as does phosphorylase b. Because removal of the amino-terminal segment changes the properties of the enzyme, this segment must be interacting with other parts of the protein. This statement conflicts with previous interpretation of X-ray crystallographic data that suggest that the amino-terminal region of phosphorylase b is freely mobile. Possible explanations for this contradiction are discussed.

Amino Acid Sequence↗
PubMed1986

Stable expression of Lyt-2 homodimers on L3T4+ T cell clones.

The murine T lymphocyte antigen Lyt-2 is considered to act as an accessory molecule to the class I-restricted T cell receptor during antigen recognition. We have previously described two unusual Lyt-2+L3T4+ class II-restricted T cell clones whose activation by antigen is inhibited by antibodies to L3T4 but not to Lyt-2 (B. Fazekas de St. Groth et al., Proc. Natl. Acad. Sci. USA 1986. 83: 2594). The Lyt-2 immunoprecipitated from one of these clones was indistinguishable from the molecule found on splenic T cells, as analyzed under reducing conditions on polyacrylamide gels, in two-dimensional charge/size separations and in peptide mapping. The molecule from the second clone showed slightly more extensive glycosylation but was within the range described for functional Lyt-2 on cytotoxic T cell lines. Lyt-2 mRNA from both clones showed no abnormalities on Northern analysis. Lyt-2 is normally expressed on thymocytes and peripheral T cells as a heterodimer disulfide bonded to the Lyt-3 glycopeptide, yet Lyt-3 could not be detected on the cell membranes of our clones; Lyt-2 existed as stable homodimers without Lyt-3. Thus Lyt-3 is not required structurally for the spontaneous expression of Lyt-2 on lymphoid cells.

Animals↗
PubMed1986

Mother's speech to their 1-year-old infants in home and laboratory settings.

The speech of mothers and their 1-year-old infants was compared in the home and in the laboratory playroom. The home and laboratory settings were similar for measuring the number of actual words that infants spoke and were similar for measuring the complexity of the mother's speech, including the number of different words, the type-token ratio, and the length of the utterances. Infants vocalized at similar rates in the two settings, but mothers spoke at a faster rate in the laboratory playroom. The usefulness of a preliminary warm-up period was supported by the finding that, for the second half of the sessions, mothers slowed their rate of speech and increased the complexity of their speech.

Female↗
PubMed1986

Mutational and in vivo methylation analysis of F-factor PifC protein binding to the pif operator and the region containing the primary origin of mini-F replication.

We have used in vivo methods to identify multiple DNA-binding sites for the negatively autoregulated mini-F replication factor PifC. Sequence analysis of pif operator constitutive mutants, isolated as insensitive to repression by PifC, establishes the structure of pifO. This site contains a 17-base-pair (bp) region of dyad symmetry with 7-bp perfect inverted repeats separated by 3 bp. In vivo DNA methylation studies with dimethyl sulfate show that the reactivity of five of six guanine residues in the pifO region is altered in the presence of PifC protein. In addition, there are several sites of PifC-dependent methylation enhancement and protection upstream of pifO within repeated sequences bearing homology to pifO. The significance of the repeated PifC binding sequences and their relationship to the primary origin of mini-F replication (oriV1) are discussed.

Bacterial Proteins↗
PubMed1986

Involvement of Lyt-2 and L3T4 in activation of hapten-specific Lyt-2+ L3T4+ T-cell clones.

The murine T-cell surface molecules Lyt-2 and L3T4 play a role in the activation of antigen-specific T cells. The currently accepted model for the function of these molecules proposes that Lyt-2 and L3T4 increase the overall avidity of the interaction between the T-cell antigen receptor and antigen in association with the major histocompatibility complex (MHC) molecules on the antigen-presenting cell. We have used two unusual Lyt-2+ L3T4+ class II MHC-restricted T-cell clones to test whether Lyt-2 can substitute for L3T4 when the T-cell antigen receptor is class II MHC-restricted. Monoclonal antibodies against L3T4 profoundly inhibited antigen-induced lymphokine production by both T-cell clones. Anti-Lyt-2 monoclonal antibody had no effect. These results strongly suggest that L3T4 and the class II-restricted T-cell antigen receptors are physically close during antigen recognition, probably as part of a multimolecular complex from which Lyt-2 is excluded. The ability of L3T4 but not Lyt-2 to participate in such a complex with class II-restricted T-cell antigen receptors may explain the striking correlation between class II restriction and L3T4 expression in the peripheral T-cell pool.

Animals↗
PubMed1986

Early conceptual loss in subfertile patients.

The incidence of early conceptual loss was studied in 27 subfertile women by measuring their serum and urine hCG levels in the luteal phase. Eleven patients eventually had clinically confirmed pregnancies, nine of whom had had significant hCG elevations in previous menstrual cycles. In the remaining 16 patients, who have so far failed to achieve a clinical pregnancy, only three had had elevated hCG results. Thus 'apparent' early conceptual loss in non-pregnancy cycles was found to be more often associated with the fertile group of patients.

Abortion, Spontaneous↗
PubMed1986

P cell stimulating factor release: a useful assay of T cell activation in vitro.

The coordinate production of multiple lymphokines by activated T cells allows the investigator a choice of assays for antigen recognition in vitro. In this paper, we examine the production of P cell stimulating factor (PSF, a lymphokine identical to interleukin 3) by L3T4+ Lyt-2-T cell clones. PSF production is antigen-specific, Ia-restricted and inhibited by a monoclonal antibody to L3T4, PSF, interferon-gamma (IFN-gamma) and interleukin 2 (IL 2) are all rapidly secreted after antigen or mitogen stimulation. The measurement of PSF avoids problems inherent in the IL 2 and IFN-gamma assays, namely absorption of IL 2 by the producer T cells and failure of the interferon assay to distinguish between interferons of the alpha, beta and gamma classes.

Animals↗
PubMed1986

Calculation of aortic valve area by Doppler echocardiography: a direct application of the continuity equation.

The continuity equation suggests that a ratio of velocities at two different cardiac valves is inversely proportional to the ratio of cross-sectional areas of the valves. To determine whether a ratio of mitral/aortic valve orifice velocities is useful in determining aortic valve area in patients with aortic stenosis, 10 control subjects and 22 patients with predominant aortic stenosis were examined by Doppler echocardiography. The ratio of (mean diastolic mitral velocity)/(mean systolic aortic velocity), (Vm)/(Va), and the ratio of (mitral diastolic velocity-time integral)/(aortic systolic velocity-time integral), (VTm)/(VTa), were determined from Doppler spectral recordings. Aortic valve area determined at catheterization by the Gorlin equation was the standard of reference. High-quality Doppler recordings were obtained in 30 of 32 subjects (94%). Catheterization documented valve areas of 0.5 to 2.6 (mean 1.1) cm2. There was good correlation between Doppler-determined (Vm)/(Va) and Gorlin valve area (r = .90, SEE = 0.23 cm2); a better correlation was noted between (VTm)/(VTa) and Gorlin valve area (r = .93, SEE = 0.18 cm2). The data demonstrate the usefulness of Doppler alone in the determination of aortic valve area in adults with absent or mild aortic or mitral regurgitation and no mitral stenosis. Although the use of mean velocity and velocity-time integral ratios requires accurate measurement of mitral and aortic velocities, it does not require squaring of these velocities or measurement of the cross-sectional area of flow.

Adult↗
PubMed1986

Pulsed Doppler study of a case of coarctation of the aorta: demonstration of a continuous Doppler frequency shift.

Pulsed Doppler echocardiography was used to assess flow across a severe coarctation of the aorta. The high peak systolic Doppler frequency shift correlated well with the gradient measured at cardiac catheterization. A Doppler frequency shift was present throughout diastole, suggesting pan-diastolic flow across the coarctation. This finding may be a marker of severe coarctation of the aorta.

Aortic Coarctation↗
PubMed1986

Suppression of glioma growth in vitro and in vivo by glia maturation factor.

Glia maturation factor (GMF), a 14,000 Mr acidic protein of the brain, is capable of promoting differentiation of cultured astroblasts. In this study we report the effect of GMF on two glioma cell lines: the C6 line, of rodent origin, and the HG-1 line, of human origin. When tested in culture, GMF promotes the initial growth of the two cell lines when the cells are sparse but limits proliferation by restoring contact inhibition when the cells are confluent. Cell cycle analysis confirms the arrest of the cells at the G0/G1 phase when the tumor cells are contact inhibited by GMF. When C6 cells are inoculated into the athymic (nude) mice at a s.c. site, a single solid tumor grows out with a 100% take. Intraperitoneal injection of GMF leads to the slowing down of tumor growth. That the in vivo effect of GMF is not due to cytotoxicity is evidenced by the lack of necrosis and by the appearance of more mature astrocytic cells in the tumors. The results lend support to the concept of GMF as a cellular regulator and suggest the therapeutic potential of GMF for brain tumors.

Animals↗
PubMed1985

Purification of bovine glia maturation factor and characterization with monoclonal antibody.

Glia maturation factor (GMF) is purified 100 000-fold to apparent homogeneity from bovine brains by a procedure consisting of ammonium sulfate precipitation, column chromatography with diethylaminoethyl-Sephacel, Sephadex G-75, and hydroxylapatite, and a final step using C4 reverse-phase high-performance liquid chromatography. The product shows a single protein band in sodium dodecyl sulfate-polyacrylamide gel. It has a molecular weight of 14 000 and an isoelectric point of pH 5.2. Purified GMF stimulates cultured astroblasts to proliferate and to grow out cell processes with half-maximal activity at 8 ng/mL. A monoclonal antibody raised against partially purified GMF adsorbs the activity of pure GMF and immunologically binds the putative GMF protein band.

Amino Acids↗