Biomedical subjects

C W Miller

Publications and source records attributed to C W Miller.

At least 109 records · Page 6Linked to original sources

PubMed1990

Expression of retinoic acid receptor mRNA in hematopoietic cells.

Retinoic acid (RA) has profound effects upon the proliferation and differentiation of many hematopoietic cells. The mechanism by which RA acts is unclear. Recently, several retinoic acid receptors (RAR) have been cloned. We studied expression of RAR-alpha mRNA by RNA blots in hematopoietic cells blocked at different stages of differentiation. All hematopoietic cells expressed RAR-alpha mRNA (3.4, 4.5 kb) including KG-1 (myeloblasts); HL-60 (promyelocytes); ML3, THP-1, U937 (myelomonoblasts and monoblasts); K562 (erythroblasts); and S-LB1 (T-lymphocytes). In addition, transformed cells from four non-hematopoietic tissues also expressed RAR-alpha mRNA. Steady-state levels of RAR-alpha mRNA were not affected by induction of terminal differentiation of HL-60 cells to either granulocytes or macrophages. Furthermore, both actively proliferating and resting lymphocytes from the same individuals expressed equal concentrations of RAR-alpha mRNA. Taken together, data suggest that level of expression of RAR-alpha mRNA is not related to cellular proliferation. We also showed that exposure to ligand (all-trans retinoic acid) did not change levels of RAR-alpha mRNA in three different cell types. Half-life of RAR-alpha mRNA was short (0.7 h) as determined by measuring decay of message after addition of actinomycin D. Consistent with this finding, accumulation of RAR-alpha mRNA increased in cells of three lines as their protein synthesis was inhibited. In summary, hematopoietic cells of different lineages and stages of differentiation constitutively express RAR-alpha mRNA. This expression is unaffected either by terminal differentiation or cell cycle. The RAR-alpha mRNA is short-lived and super-inducible by a protein synthesis inhibitor.

Carrier Proteins↗

PubMed1990

Free skin flap transfer by microvascular anastomosis.

Free skin flap transfer by microvascular anastomosis has proven to be a successful technique for covering difficult to treat skin defects. Specialized equipment and training restrict its application to large teaching or specialty practices. Currently, this training is only available through medical schools; however, skin is only one of many tissues to which distant transfer by microvascular anastomosis is applicable. The potential uses of microvascular free tissue transfer ensure its expanded use in veterinary surgery.

Anastomosis, Surgical↗

PubMed1990

Examination of the impact of radioactive liquid effluent releases from the Rancho Seco Nuclear Power Plant.

A project has been carried out by Oak Ridge National Laboratory (ORNL) to estimate the concentrations of radionuclides in the environment resulting from the release of radioactive materials in the liquid waste effluents from the Rancho Seco Nuclear Power Plant (RSNPP) and to estimate possible radiation doses to man resulting from current environmental concentrations. To accomplish the objectives of this project, ORNL staff members conducted an environmental sampling program around the plant site during November and December 1984. Elevated levels of some anthropogenic radionuclides were found in the immediate environment of the plant. This radioactive contamination occurs primarily along streams receiving effluent from the plant and in fields irrigated with water from these streams. The primary contaminants are 137Cs and 134Cs, with lesser amounts of 60Co and 58Co. The ingestion of fish was the single most important pathway identified in this analysis. However, all specific pathways of exposure and usage factors were not precisely known for a complete dose assessment of current and potential use of contaminated water and soil around the RSNPP. The liquid effluent radionuclide releases from the RSNPP pose no significant health hazard to persons living near the RSNPP.

California↗

PubMed1990

Dual-energy radiographic absorptiometry of the lumbar spine: clinical experience with two different systems.

Dual-energy radiographic absorptiometry (DRA) of the lumbar spine was performed in 222 subjects (aged 17-92 years) of both sexes with use of two different systems. In a sub-group of 21 patients, results were compared with those obtained by means of dual-photon absorptiometry (DPA) of the lumbar spine. There was a high correlation among the results obtained with three instruments (r = .9, P less than .0001), and interconversion factors were calculated. Data conversion based on these regression equations may be useful for comparing results from one laboratory to another.

Absorptiometry, Photon↗

PubMed1990

Applications of microvascular surgery.

The advent of microvascular surgery has radically changed the discipline of human reconstructive surgery over the last decade. The ability to anastomose vessels less than 1 mm in diameter allows the distant transfer of tissues with a known blood supply from one area of the body to another. These tissues can be detached from their local blood supply and reperfused by anastomosing vessels supplying the tissue transfer to vessels near the recipient site. This technique has been used to transfer a variety of tissues and combinations of tissues including skin, muscle, bone, and bowel to solve a variety of difficult reconstructive problems. Applications, potential applications, and problems associated with microvascular free tissue transfer will be discussed in this chapter.

Anastomosis, Surgical↗

PubMed1990

Facial reconstruction.

Reconstruction of the facial and mandibular areas has received little attention in small animal surgery. Defects requiring reconstruction are often the result of trauma or neoplasia. This chapter explores problems of the maxillary, nasal, and mandibular areas, and describes recent surgical advancements that have application in these cases.

Animals↗

PubMed1990

Cholesterotic fibrous histiocytoma. Its association with hyperlipoproteinemia.

A 63-year-old woman with fibrous histiocytomas showed cholesterol deposition in the setting of type IIB hyperlipidemia. The two lesions involved the left leg and right thigh. One had typical features of a fibrous histiocytoma including changes of the overlying epidermis. The other was essentially replaced by cholesterol deposits and could not be differentiated from a tuberous xanthoma. This case illustrates the histiocytic response of fibrous histiocytomas to a hyperlipoproteinemic microenvironment.

Cholesterol↗

PubMed1990

Retrospective analysis of ras gene activation in myeloid leukemic cells.

Ras genes are activated by point mutations at critical sites of their coding regions. Activated N-ras genes with transforming ability have been detected in patients with myelodysplastic syndromes (MDS), acute myelogenous leukemia (AML) and in human myeloid cell lines. We used polymerase chain reaction (PCR), differential oligonucleotide hybridization and direct DNA sequencing to retrospectively analyze the N-ras gene of blast cells from the same patient (a) at time of diagnosis of MDS, (b) after the patient had developed AML. Two types of archival tissue samples served as a source of cells. Different passages of the KG-1 myeloid cell line which had been established from leukemic blasts of this patient were also analyzed. We found that native blast cells isolated at either of the two disease stages did not carry an N-ras mutation, and neither did early passage KG-1 cells. However, direct DNA sequencing of PCR-amplified DNA from nude mice transformants induced by DNA from late passage of the KG-1 cell line revealed two linked mutations involving both the second nucleotide of codon 12 and the third nucleotide of codon 15 of N-ras. The nucleotide substitution at codon 15 did not result in an amino acid substitution (silent mutation). The mutations probably occurred during prolonged passaging of the KG-1 cells and might have been overlooked by oligonucleotide hybridization assay.

Animals↗

PubMed1990

A potential transcriptional activation element in the p53 protein.

The human p53 gene codes for a 393 amino acid nuclear phosphoprotein. p53 is most commonly described as a tumor suppressor, or anti-oncogene, although its role in vivo remains unclear. We report that GAL4-p53 fusion protein can activate transcription of a CAT reporter gene downstream of a GAL4-DNA binding site. We tested both the amino terminal 160 amino acids and the carboxyl terminal 233 amino acids of the p53 protein and found that the transcriptional activating (TA) region was restricted to the amino terminal fragment. These results imply that p53 may be a transcriptional activating factor (TAF); furthermore, these data lend support to the hypothesis of p53 as a positive regulator of transcription which might mediate its tumor suppressor role by inducing expression of a set of genes with a negative effect on cellular growth.

Animals↗

PubMed1989

Evidence for a pretranslational defect in hereditary and acquired myeloperoxidase deficiency.

Myeloperoxidase (MPO) is a heme containing enzyme involved in the oxygen-dependent microbicidal activity of human polymorphonuclear leukocytes (PMN). Complete hereditary and acquired MPO deficiencies are defined as lack of peroxidase activity in PMN. Using this criterion, we studied a patient with complete hereditary MPO deficiency, and a MPO deficient variant cell line of HL-60 (HL-60-A7), which we used as a model for acquired MPO deficiency. Western blot analysis showed complete absence of mature and precursor protein of MPO both in PMN from the patient and in HL-60-A7 cells. PMN from both parents had one half of normal levels of these proteins. To study further the molecular basis of this defect, we isolated an intron specific probe for MPO and used it and a cDNA probe. Both normal human bone marrow cells and the promyelocytic HL-60 leukemia cells contained MPO mRNA species of 2.8, 3.3, approximately 4, and greater than 8 kilobase (kb). The transcripts of greater than 8 and approximately 4 kb contained sequences hybridizing to a probe specific for intron 7 of the MPO gene. Bone marrow cells of the MPO deficient patient contained two species of heterogeneous nuclear (hn) RNA of greater than 8 and approximately 4 kb, but only trace amounts of the normal sized 3.3 kb MPO mRNA and undetectable 2.8 kb MPO mRNA. HL-60-A7 cells contained both greater than 8 and approximately 4 kb hnRNA, but only small amounts of normal sized 2.8 kb MPO mRNA and undetectable levels of the 3.3 kb mRNA. Southern blot analyses revealed no gross alteration of the MPO gene in both cases. Our results suggest that a pretranslational defect is one mechanism leading to MPO deficiency.

Adult↗

PubMed1989

Thrombolysis with a snake venom protease in a rat model of venous thrombosis.

A fibrin(ogen)olytic protease isolated from the venom of Crotalus atrox (the western diamondback rattlesnake) was tested for thrombolytic activity. The protease, called atroxase, solubilized fibrin when tested on fibrin plates and hydrolyzed fibrinogen rendering it incoagulable with a specific fibrinogenolytic activity of 42 mg fibrinogen/min/mg protein. Atroxase was unable to activate plasminogen. In vivo, fibrinolytic activity was tested on artificial thrombi induced in the posterior vena cava of Sprague-Dawley rats. Thrombolysis was then characterized by angiographic techniques over a period of three hours. Intravenous administration of the protease, at a dosage of 6.0 mg/kg, resulted in thrombolysis within one hour followed by recanalization of the originally occluded vein within two hours. Fibrinogenolytic activity resulted in a 60% decrease in the rat's plasma fibrinogen level. Histological examination of kidney, liver, heart and lung tissue showed no necrosis nor hemorrhage. These results are the first step in evaluating the thrombolytic potential of anticoagulant proteases within C. atrox venom using laboratory animals.

Angiography↗

PubMed1989

Diffuse idiopathic skeletal hyperostosis: diagnostic significance of radiographic abnormalities of the pelvis.

Retrospective evaluation of the osseous pelvis in 93 patients with severe diffuse idiopathic skeletal hyperostosis (DISH) revealed 14 locations of radiographic abnormalities. Two osteoradiologists independently studied these sites for abnormalities in a prospective, blinded fashion in 103 patients over the age of 45 years. Lateral radiographs of the thoracolumbar spine were quantitatively and qualitatively evaluated to determine whether DISH, spondylosis deformans, or a normal spine was present. Statistical analysis was performed for evaluation of interobserver reliability, the relationship between pelvic and spinal abnormalities, and the significance and predictive values of pelvic abnormalities for DISH versus non-DISH and DISH versus spondylosis deformans. Although significantly higher frequencies and greater extents of radiographic abnormalities at 10 of 14 pelvic locations were noted for DISH compared with non-DISH, this number decreased to four of 14 locations when compared with spondylosis deformans. The alterations in three of these four pelvic sites consisted of ossification of ligaments. These changes appear to be good indicators of the presence of spinal DISH and support the concept that DISH is an entity separate from spondylosis deformans.

Adult↗

PubMed1989

A Ph1 chromosome positive B cell line expresses the fusion protein P 210.

We established a B lymphocyte line from bone marrow cultures of a patient with Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia. The cell line (MB) is positive for Ph1 and has the phenotype of mature B lymphocytes transformed by the Epstein-Barr virus (EBV). When DNA was isolated and hybridized to specific cDNA probes, a rearranged immunoglobulin gene and EBV-sequences were detected. On Western blots of cell extracts, the novel fusion protein (P 210) was demonstrated with antisera against bcr and v-abl proteins. These results confirm the concept that B lymphocytes in CML can be involved in the malignant clone and demonstrate that these B cells express the fusion protein.

Adult↗

PubMed1989

Expression, methylation and chromatin structure of the p53 gene in untransformed and human T-cell leukemia virus type I-transformed human T-lymphocytes.

p53 is a nuclear protein associated with cellular transformation and normal cellular proliferation. Some transformed cells have been found to have one or several quantitative or qualitative abnormalities of p53. We studied expression, kinetics, phosphorylation, DNA methylation and chromatin structure of p53 in resting and proliferating untransformed T-lymphocytes and in human T-cell leukemia virus type I transformed T-lymphocytes from the same individuals. p53 expression is indistinguishable in transformed compared to untransformed proliferating T-lymphocytes by: (1) p53 mRNA levels, (2) rate of synthesis and stability of p53 protein, (3) change in protein stability after exposure to an inhibitor of protein synthesis, (4) presence of phosphorylation of the p53 protein. Resting T-lymphocytes from these same individuals did not express p53. No difference in DNA methylation and chromatin structure of the p53 gene was observed in either resting or proliferating untransformed, or virally transformed T-lymphocytes. The gene was fully methylated and resistant to DNAase I over its entire coding region but was demethylated and contained DNAase I hypersensitive sites in a distinct region 5' of the site of initiation of transcription.

Cell Line↗

PubMed1988

Treatment of cyclophosphamide-induced hemorrhagic cystitis in five dogs.

Sterile hemorrhagic cystitis developed in 5 dogs after treatment with cyclophosphamide. Four dogs were being treated with various antineoplastic protocols, and the fifth dog had recurrent immune-mediated thrombocytopenia. In all instances, clinical signs of hematuria and stranguria persisted after cyclophosphamide administration was discontinued. Three dogs required cystotomy to remove necrotic mucosa and calculi. The other 2 dogs were treated with intravesicularly administered dimethyl sulfoxide to decrease inflammation and to inhibit fibroplasia of the bladder wall. In 4 dogs, clinical signs resolved after treatment. The fifth dog, treated surgically, continued to have intermittent urinary incontinence attributable to residual bladder wall fibrosis.

Animals↗

PubMed1988

p53 in chronic myelogenous leukemia. Study of mechanisms of differential expression.

The p53 is a nuclear protein that is associated with normal cellular proliferation and can cooperate with Ha-ras in causing cellular transformation in vitro. Lineage association is known to exist between p53 expression and normal lymphopoiesis, but not myelopoiesis. We studied the expression of p53 using chronic myelogenous leukemia (CML) cell lines, somatic hybrids of these cells, and leukemic cells from CML patients. Lymphoid CML lines expressed both p53 mRNA and protein. We also analyzed p53 synthesis by two B-lymphoid lines from the same CML patient; cells of one line were derived from the neoplastic clone, cells of the other were derived from the normal clone. Both synthesized equal amounts of a phosphorylated p53 protein. None of the myeloid CML lines expressed detectable p53 protein and two of four expressed negligible p53 mRNA. Two other myeloid CML lines and myeloid cells from three of four patients expressed p53 mRNA. These findings suggest that expression of the gene is not regulated normally in CML. Several approaches were pursued to explore the differential expression of p53. Southern blot analyses showed no gross alterations in the p53 gene from cells of either the expressing or the nonexpressing lines. No difference in the pattern of demethylated CpG sites was noted in the region of the p53 gene in cells from K562 (myeloid p53 nonexpressor) and in BV173 (lymphoid p53 expressor). The sites of demethylation clustered in and around the p53 promoter in both cell lines. Somatic hybrids formed between a p53 mRNA nonexpressor myeloid line (K562) and the parental p53 expressor lymphoid lines (Daudi, PUT) produced p53 mRNA and protein, suggesting that p53 is a dominantly expressed protein and that lack of expression in myeloid cells is not mediated by a trans-acting negative regulatory protein. DNA transfection experiments performed using the indicator gene chloramphenicol acetyltransferase attached to promoter sequences of p53 showed that these constructs were equally activated in BV173 (p53 expressor) and K562 (p53 mRNA nonexpressor). The mechanism of p53 regulation in CML remains unclear.

Blast Crisis↗

PubMed1988

Regulation of gene expression of myeloperoxidase during myeloid differentiation.

Myeloperoxidase (MPO) is a major heme enzyme involved in inflammatory responses of polymorphonuclear leukocytes. Using cDNA and intron specific probes for MPO we studied the regulation of MPO expression during myeloid differentiation of the promyelocytic HL-60 leukemia cell line. Mature MPO mRNA species of 3.3, 2.8 and 1.6 kb and heterogeneous nuclear (hn) RNA of greater than 8 and approximately 4 kb were observed in wildtype HL-60 cells. Induction of differentiation of the cells towards either granulocytes or macrophages resulted in a profound decrease (greater than 95%) in the concentration of MPO mRNA levels, showing that gene expression of MPO mRNA is closely linked to the stage of development of myeloid cells. Studies using normal and leukemic hematopoietic cells confirmed these findings and showed that myeloblasts and promyelocytes contain MPO mRNA. Rate of transcription of MPO was measured by a nuclear run-on assay in wild-type and day 3- and day -4 differentiated HL-60 cells and was nearly the same in all three. In contrast, rate of transcription of c-myc in the same nuclei became almost undetectable with induction of differentiation. Overall transcription decreased by 60% and 80% on day 3 and 4 of differentiation, respectively, compared to wild-type cells. Stability of mature MPO mRNA was also measured and found to be the same in wild-type and differentiated HL-60. Half-life of MPO hnRNA was less than or equal to 30 min in wild-type HL-60; nevertheless, this hnRNA was easily detectable 3 days after induction of differentiation of these cells. Taken together, the results show that decreased expression of MPO mRNA with differentiation occurs in part post-transcriptionally, possibly due to a failure in RNA processing. In addition, as overall transcription decreases during differentiation, MPO transcription is concomitantly reduced. This indicates that transcriptional and post-transcriptional mechanisms cooperate in the control of MPO gene expression.

Cell Differentiation↗

PubMed1988

Examination of the uncertainty in air concentration predictions using Hanford field data.

The accuracy of an environmental transport model is best determined by comparing model predictions with environmental measurements made under conditions similar to those assumed by the model, a process commonly referred to as model validation. Over the past several years, we have done a variety of validation studies with the popular Gaussian plume atmospheric dispersion model using data from tests conducted on the Hanford site. Data for short-term releases of small particles for a range of release heights from surface level to 111 m have been used. Downwind distances examined have ranged from a few hundred meters to 12.8 km, depending on the particular data used. Measured and predicted ground-level centerline, crosswind-integrated, and 22.5 degrees sector-averaged air concentrations have been compared. Up to six different sets of atmospheric dispersion parameters and three different atmospheric stability class specification schemes have been examined. Overall, dispersion parameters based on measurements made near Jülich, Federal Republic of Germany, give the best comparisons between observed and predicted air concentrations. The commonly used vertical temperature gradient method for determining atmospheric stability class consistently gives poor results. The accuracy of air concentration predictions improves when dry deposition processes are included in the model. Further validation studies using various Hanford data sets are planned.

Air Pollutants↗