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R W Miller

Publications and source records attributed to R W Miller.

At least 37 records · Page 2Linked to original sources
PubMed1997

Covalent modification of nitrogenase MoFe protein by ADP.

MgADP- reacted with the nitrogenase molybdenum-iron (MoFe) protein of Klebsiella pneumoniae (Kp1) over a period of 2 h to yield a stable, catalytically active conjugate. The isolated protein exhibited a new, broad 31P NMR resonance at -1 p.p.m. lacking phosphorus J coupling. The adenine ring of [8-14C]ADP remained associated with the conjugate. A covalently bound nucleotide was identified as AMP by NMR and TLC. Extended dialysis of Kp1 against MgADP- resulted in further AMP binding at the protein surface. ADP was initially bound tightly to Kp1 at a site distinct from the AMP sites. ATP did not replace ADP. The time course of the formation of the Kp1-AMP was altered by the nitrogenase iron protein (Kp2) and was dependent on redox potential. Kp1-AMP was stable to concentration and oxidation with ferricyanide ion at -350 mV. Slow hydrolysis of Kp1-AMP over a period of 6 h yielded AMP and unaltered Kp1. The adenine ring of ADP exchanged with adenine of MgATP2- during reductant-limited turnover of nitrogenase under N2, indicating reversibility of ATP hydrolysis at 15 degrees C. [32P]Pi exchanged with the terminal phosphate group of both ADP and ATP on incubation with Kp1. 32P exchange and the catalytic activity of Kp1 were inhibited by a 20-fold molar excess of the lysine-modifying reagent, o-phthalaldehyde (OPT). Preincubation with MgADP- protected against OPT inactivation. Two potentially reactive lysine residues on the alpha chain of the MoFe protein near a putative hydrophobic docking site for the nitrogenase Fe protein are proposed as sites of OPT and nucleotide binding. Azotobacter vinelandii MoFe protein (Av1) also formed an AMP adduct but Kp2 did not. Catalase did not interact with ADP. The reactions of the nitrogenase MoFe protein with adenine nucleotides have no counterpart in known protein-nucleotide interactions.

Adenosine Diphosphate↗
PubMed1997

Pegylated peptides. V. Carboxy-terminal PEGylated analogs of growth hormone-releasing factor (GRF) display enhanced duration of biological activity in vivo.

In the present study, human growth hormone-releasing factor (hGRF) and analogs were successfully pegylated at the carboxy-terminus using a novel solid- and solution-phase strategy. Following synthesis, these pegylated hGRF analogs were evaluated for in vitro and in vivo biological activity. Specifically, hGRF (1-29)-NH2, [Ala15]-hGRF (1-29)-NH2, [desNH2Tyr1, D-Ala2, Ala15]-hGRF(1-29)-NH2 and [His1, Val2, Gln8, Ala15, Leu27]-hGRF(1-32)-OH were each C-terminally extended using a Gly-Gly-Cys-NH2 spacer (previously demonstrated not to alter intrinsic biological activity), and then monopegylated via coupling to an activated dithiopyridyl-PEG reagent. PEG moieties of 750, 2000, 5000 or 10,000 molecular weight (MW) were examined to determine the effect of polymer weight on activity. Initial biological evaluations in vitro revealed that all C-terminally pegylated hGRF analogs retained high growth hormone (GH)-releasing potencies, regardless of the MW of PEG polymer employed. Two of these pegylated hGRF analogs, [desNH2Tyr1, D-Ala2, Ala15]-hGRF (1-29)-Gly-Gly-Cys(NH2)-S-Nle-PEG5000 and [His1, Val2, Gln8, Ala15, Leu27]-hGRF(1-32)-Gly-Cys(NH2)-S-Nle-PEG5000, were subsequently evaluated in both pig and mouse models and found to be highly potent (in vivo potency range = 12-55-fold that of native hGRF). Relative to their non-pegylated counterparts, these two pegylated hGRF analogs exhibited enhanced duration of activity.

Animals↗
PubMed1997

Radioprotection of hematopoietic tissue by fibroblast growth factors in fractionated radiation experiments.

Acidic and basic fibroblast growth factors (FGF(1/2)) myeloprotect mice in single dose total body irradiation (TBI) experiments with a dose modification factor (DMF) of approximately 1.15. CFU-C assay suggests that one of the mechanisms is augmentation of the shoulder of the radiation dose response curve, and thus protection could be greater with fractionation. Four equal fractions of TBI were delivered to C3H/He mice at times 0 h, 8 h, 24 h, and 32 h. FGF(1/2) dose was 3 microg per i.v. injection given 24 and 4 hrs before the first radiation dose. FGF2 treated mice had a significant survival advantage over saline-treated mice with a DMF of 1.22 +/- 0.07 (p < 0.01). Adding a third dose of FGF2, had no additional benefit on LD(50/30) (dose of radiation lethal to 50% of animals measured at day 30) (DMF = 1.23 +/- 0.06, p < 0.01). FGF1 was not as effective with fractionation (DMF = 1.04 +/- 0.03). Increased survival in FGF2 treated mice was due to the a more rapid recovery of bone marrow hematopoietic cells and peripheral WBC, RBC and platelets. FGF2 may prove a useful treatment response modifier in clinical fractionated irradiation.

Animals↗
PubMed1996

An approach to dose measurement for total body irradiation.

PURPOSE: An approach is proposed to allow the interpretation of diode measurements on patients receiving total body irradiation (TBI) in opposed lateral fields as midplane dose measurements. METHODS AND MATERIALS: This technique consists of making measurements on both entrance and exit sides of any ray path along which the midplane dose is desired. The diode on the entrance side is calibrated so that its output is indicative of the dose delivered at the depth of maximum dose along the ray. The diode on the exit side is calibrated so that its output represents the dose that would have been delivered to that depth had the medium (the patient) been semi-infinite. Because these two measurements lie along the same ray, they are related by a simple depth-dose equation from which the effective absorption coefficient (mueff) can be determined. The dose at the midplane is calculated using this mueff in a similar equation. RESULTS: The validity of this approach was checked with measurements at isocenter and at the TBI distance using a polystyrene phantom. In both cases, the calculated midplane dose was within reasonable experimental error (range approximately +/- 2% on average) of the measured dose. Measurements on eight patients showed the excellent reproducibility of entrance surface measurements (standard deviation [SD] approximately +/- 1%), compared to that of midplane measurements (SD approximately +/- 4%) and exit surface measurements (SD approximately < or = 8%). Midplane doses determined from these equations confirmed that dose inhomogeneity using this opposed lateral technique is on the order of +/- 10% with highest doses delivered to the calves and lowest to the lungs. CONCLUSION: Recent measurements made on TBI patients have shown that a commercial eight-diode system can be used successfully to measure the dose delivered to the midplane within an accuracy of approximately +/- 4%. The reproducibility of entrance surface measurements (approximately +/- 1%) shows that such measurements provide the accuracy required for quality assurance purposes.

Calibration↗
PubMed1996

Quantitative comparisons of continuous and pulsed low dose rate regimens in a model late-effect system.

PURPOSE: There is increasing interest and usage of pulsed low dose rate (PDR) brachytherapy, in which a single source is shuttled through the catheters of an implant, typically for about 10 min each hour. This study was designed to compare the late effects produced in various PDR regimens with those from the corresponding continuous low dose rate (CLDR) regimens. METHODS AND MATERIALS: A model late-responding system was used, namely, cataract induction in the rat lens. This system has the advantage of being highly quantifiable. The rats eyes were exposed to a total dose of 15 Gy either continuously over 24 h, or with three different PDR regimens, all with the same total dose and overall time. We addressed three questions: (a) are late effects increased when a CLDR regimen is replaced with 10-min pulses repeated every hour? (b) Are late effects increased if hourly 10-min pulses are replaced with 10-min pulses repeated every 4 h? (c) Are late effects increased if 10-min pulses are replaced with 100-s pulses? RESULTS: We found that the four regimens under test, continuous, 10-min pulses each hour, 10-min pulses every 4 h, and 100-s pulses every hour, showed no significant differences in cataractogenic potential, as estimated with the Wilcoxon-Gehan test. Power tests indicated that the experimental design was adequate to detect relatively small differences in cataractogenicity between regimens. CONCLUSIONS: The equality of late effects from CLDR and PDR in these experiments must imply that sublethal damage repair is quite slow in this model late-responding system, in agreement with trends observed in the clinic for sublethal damage repair of late sequelae. Such trends would suggest that PDR is unlikely to produce significantly worse late effects than the corresponding CLDR regimen, which is in agreement with early clinical data using PDR. Caution, however, is strongly recommended.

Animals↗
PubMed1996

T cell rescue of monocytes from apoptosis: role of the CD40-CD40L interaction and requirement for CD40-mediated induction of protein tyrosine kinase activity.

Circulating monocytes have a limited life span and will undergo apoptosis in the absence of specific stimuli. Recent studies have demonstrated that monocytes can be rescued from apoptosis via lipopolysaccharide (LPS) activation or stimulation with interleukin-1 or tumor necrosis factor-alpha. Based on previous studies from our laboratory, we hypothesized that, in nonseptic (e.g., autoimmune) inflammation, the presence of activated T cells may enhance monocyte longevity through T cell contact-dependent signaling. Plasma membranes prepared from 6 h activated (TmA) and resting (TmR) purified CD4+ T cells were added to resting elutriation-purified monocytes cultured in serum-free medium. Cells were assayed for degree of apoptosis occurring over a 72-h incubation using both agarose gel electrophoresis and flow cytometry. The addition of TmA (but not TmR) was capable of blocking monocyte apoptosis and the ability of TmA to rescue monocytes was abrogated by the addition of anti-CD40L antibodies. Rescue of monocytes from apoptosis could also be mediated by direct cross-linking of monocyte CD40. Inhibitors of tyrosine kinase activity blocked both TmA and anti-CD40-mediated rescue of monocytes from apoptosis, suggesting a primary role of a tyrosine kinase signaling pathway in the events controlling monocyte longevity.

Apoptosis↗
PubMed1996

Urine delivery of cyromazine for suppressing house and stable flies (diptera: muscidae) in outdoor dairy calf hutches.

In a series of 4 trials, dairy calves housed in outdoor hutches were administered technical cyromazine daily at rates of 0, 0.1, 0.5, and 1.0 mg/kg body weight. Cyromazine was excreted primarily in the urine. The 2 highest rates prevented the development of immature stages of both the house fly, Musca domestica L., and the stable fly, Stomoxys calcitrans (L.). Analysis of calf body tissues for cyromazine and its metabolite, melamine, indicated that highest combined residues ( < or = 0.35 ppm) were found in the kidney. Lower levels of residues were found in kidney fat and liver, and occasionally in round muscle.

Administration, Oral↗
PubMed1996

The U.S.-Japan Cooperative Cancer Research Program: some highlights of seminars, interdisciplinary program area, 1981-1996.

Thirty-one seminars have been held in the 16 years since 1981. A principal interest from the beginning was the genetics of cancer, well before this subject became widely popular. This interest arose in part because of marked binational differences in type-specific cancer rates, such as the very low rates among Japanese for Hodgkin's disease in the young, testicular cancer, Ewing's sarcoma, superficial spreading melanoma, chronic lymphocytic leukemia, and Wilms' tumor (half the U.S. frequency). Three seminars were devoted to the seeming reciprocal relationship between B-cell lymphoma (low in Japan) and certain autoimmune diseases (high in Japan), which is perhaps similar in origin to the male/female differences in the rates for these diseases. A seminar on Li-Fraumeni syndrome led to the recognition of cases among Japanese pedigrees brought to the meeting, and generated a study of its occurrence in Japanese families with adrenocortical carcinoma in a child. Another seminar revealed a marked clustering of rare cancers in Werner's (premature aging) syndrome in Japan, and led to a binational study and analysis of case-reports worldwide. Three seminars on pathology heightened appreciation of the importance of subclassifying cancer by subsite and subtype for racial and other comparisons. Four seminars on biostatistics in cancer research generated a substantial exchange of specialists and trainees in this field.

Adult↗
PubMed1996

Excess of rare cancers in Werner syndrome (adult progeria).

The association between genetic disorders and diverse cancers has provided clues for laboratory research into carcinogenesis. Such an opportunity now arises from studies of cancer in Werner syndrome (WRN). Soft-tissue sarcoma (STS) and benign meningioma have been associated with WRN, an autosomal recessive disorder characterized by premature aging, more commonly reported in Japan than elsewhere, in part because of inbreeding. In the literature we found 124 case-reports of neoplasia and WRN from Japan and 34 from outside Japan, 1939-August, 1995. They reveal a greater diversity of neoplasia in WRN than was previously known. In Japanese, there were 127 cancers, 14 benign meningioma, and 5 myeloid disorders, as compared with 30, 7 and 2 respectively in non-Japanese. The ratio of epithelial to non-epithelial cancers was about 1:1 for Japanese and for non-Japanese instead of the usual 10:1. Both series had excess of STS, osteosarcoma, myeloid disorders, and benign meningioma. In addition, the Japanese had an excess of thyroid cancer (20 versus 2 cases in non-Japanese) and melanoma (21 versus 3 cases), including 5 intranasal and 13 of the feet. STS, osteosarcoma, melanoma, and thyroid carcinoma accounted for 57% of all cancer in WRN as compared with 2% expected based on the Osaka population at 25-64 years of age. Multiple tumors were reported in 19 Japanese and 5 non-Japanese. In Japan, nine first-degree relatives had WRN and cancer, six of whom were concordant as to site and/or cell type. The WRN gene has been mapped to chromosome 8p. The high frequency of thyroid cancer and melanoma in Japanese, not found in Caucasians, may be related to a report of linkage disequilibrium with the WRN gene in Japanese but not in Caucasians and to haplotype differences within and between the two races, suggesting multiple independent mutations.

Adult↗
PubMed1995

Dosimetric considerations in treating mediastinal disease with mantle fields: characterization of the dose under mantle blocks.

PURPOSE: While the rationale for using mantle fields is well understood and the prescription of these fields is straightforward, the underlying complexity of the dose distributions that result is not generally appreciated. This is especially true in the choice of lung block design, which affects the dose to both the target volume as well as to the normal lung tissue. The key to the design of optimal lung blocks is the physician's perception of the complex relationship between the geometric and dosimetric aspects of heavily modified fields, as well as how the physical and anatomical properties of the target volume and the shape of the patient's lungs relate to the images visualized on simulator films. METHODS AND MATERIALS: Depth doses and cross-beam profiles of blocks ranging in width from 1 cm to 10 cm were taken using an automated beam scanning system. These data were then converted to "shadow fields." The results were compared to open fields of the same size using standard methodology. RESULTS: Shadow fields behave quite similarly to small, open fields in terms of x-ray-light field congruence, flatness, symmetry, and penumbra. There is a 2-3 mm rim between the edge of the block and the point at which it becomes nominally effective. The dose at the center of a block, which gives the normalization of the shadow fields, is given by a block transmission factor (BTF), which produces results in excellent agreement with measurements over a wide variety of block sizes and tissue depths. CONCLUSION: The radiation dose under shielding blocks can be considerably higher than expected, and care must be exercised when drawing blocks close to critical structures. The effects of blocks can be described in terms of normalized shadow fields, which behave similar to narrow, open fields, but with a divergence characteristic of their position relative to the radiation source. The normalization value for these fields, which gives the relative dose under the block, can be obtained from a straightforward analytical expression, the BTF.

Lung↗
PubMed1995

Tumors in Rubinstein-Taybi syndrome.

The 14 tumors reported in Rubinstein-Taybi syndrome since 1989, when added to the 22 previously reported, are beginning to show a pattern of neural and developmental tumors, especially of the head, which is malformed in the syndrome. Among the neoplasms were 12 of the nervous system: 2 each of oligodendroglioma, medulloblastoma, neuroblastoma, and benign meningioma, a pheochromocytoma, and 3 other benign tumors; 2 of nasopharyngeal rhabdomyosarcoma; and 1 each of leiomyosarcoma, seminoma, and embryonal carcinoma. Among the other benign tumors were an odontoma, a choristoma, a dermoid cyst, and 2 pilomatrixomas.

Adolescent↗
PubMed1995

Childhood cancer.

BACKGROUND: Cancers of individual organs generally are composed of various histologic types, each with its own frequency and demographic patterns. For childhood cancers in particular, a classification of cancers by histologic type is important for understanding the etiology and progression of the disease. METHODS: Data from the Surveillance, Epidemiology, and End Results (SEER) Program on 9308 microscopically confirmed malignant neoplasms in children younger than age 15, newly diagnosed during 1973-1987, were made available for analysis. Tumors were grouped histologically according to a classification previously utilized in an international volume of childhood cancer incidence. RESULTS: The most frequent histologic types were acute lymphocytic leukemia (23.6%), astrocytoma (9.6%), neuroblastoma (6.6%), and Wilms' tumor (6.4%). Acute lymphocytic leukemia accounted for 75% of childhood leukemia. The most common form of Hodgkin's disease was the nodular sclerosing subtype, which was diagnosed in 56% of all cases. Burkitt's and Burkitt-like disease accounted for approximately one third of non-Hodgkin's lymphoma, the sex ratio (male to female) being unusually high (5.7). Among the brain tumors, glioma was of interest because 198 cases (excluded from this analysis) were diagnosed without histologic confirmation--due, no doubt, to their inaccessibility for biopsy because they were located in the brain stem. The most common histologic type of soft tissue sarcoma was rhabdomyosarcoma, which accounted for 51% of the total, more than half of which were of the embryonal type. To the authors' knowledge, this report offers for the first time the relative frequencies of rare types of leukemias, such as megakaryoblastic leukemia, in childhood. This report also includes the frequencies of 21 rarer forms of soft tissue sarcoma. Five forms of childhood cancer had a 5-year relative survival rate of 85% or better. Of the cancers with the poorest outcome, three had relative survival rates of 46.5-49%; the relative survival rate of acute myelogenous leukemia was only 26.4%. The trends in survival over time for 21 types of childhood cancer also are included in this report. CONCLUSIONS: Further refinements in classification now are available through laboratory techniques utilizing molecular biology, immunology, and cytogenetics, which are of importance in etiologic studies, diagnosis, treatment, and prognosis. It would be important in the future for cancer registries to record the results of relevant laboratory tests for further analysis by subtype.

Adolescent↗
PubMed1995

T cell--vascular smooth muscle cell interactions: antigen-specific activation and cell cycle blockade of T helper clones by cloned vascular smooth muscle cells.

Histological observations have demonstrated the presence of T lymphocytes in atherosclerotic plaques, often in close association with vascular smooth muscle cells (VSMC). We have examined the interaction occurring between cloned murine VSMC and histocompatibility-matched, antigen-specific Th1 and Th2 cell lines. Incubation of either Th1 or Th2 cells with antigen-pulsed VSMC resulted in the formation of T cell-VSMC conjugates accompanied by morphological changes in both cell types. This interaction resulted in an antigen-dependent activation of IL-2 receptor expression by the Th cells, demonstrating the ability of cloned VSMC to process and present antigen through the exogenous pathway. However, although the T cells were activated to express IL-2 receptors by antigen-pulsed VSMC, they were unable to progress through cell cycle. The secretion of an inhibitory mediator by VSMC was suggested by the observations that (1) fixation of the VSMC's eliminated the inhibitory signal and (2) the supernatants of IFN gamma-primed VSMC displayed similar inhibitory activity. The inhibitory effect could not be abrogated with indomethacin or an inhibitor of the generation of reactive nitrogen intermediates, indicating that prostaglandin synthesis and/or nitric oxide production are not solely responsible for the inhibition of proliferation. Flow cytometric cell cycle analysis revealed that VSMC delivered signals resulting in a late G1 blockade of T cell cycle progression. Mitogen responses of purified primary T cells are also dramatically inhibited by IFN gamma-treated VSMC, despite significant IL-2 production. Our data depict a complex and intimate T cell-VSMC interaction and suggest that mutual activation events may occur.

Animals↗