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Biomedical subjects

D M Miller

Publications and source records attributed to D M Miller.

At least 145 records · Page 8Linked to original sources
PubMed1991

Effects of ceruloplasmin on superoxide-dependent iron release from ferritin and lipid peroxidation.

Ceruloplasmin (CP) effectively inhibited superoxide and ferritin-dependent peroxidation of phospholipid liposomes, using xanthine oxidase or gamma irradiation of water as sources of superoxide. In addition, CP inhibited superoxide-dependent mobilization of iron from ferritin, suggesting that CP inhibited lipid peroxidation by decreasing the availability of iron from ferritin. CP also exhibited some superoxide scavenging activity as evidenced by its inhibition of superoxide-dependent cytochrome c reduction. However, superoxide scavenging by CP did not quantitatively account for its inhibitory effects on iron release. The effects of CP on iron-catalyzed lipid peroxidation in systems containing exogenously added ferrous iron was also investigated. CP exhibited prooxidant and antioxidant effects; CP stimulated at lower concentrations, reached a maximum, and inhibited at higher concentrations. However, the addition of apoferritin inhibited CP and Fe(II)-catalyzed lipid peroxidation at all concentrations of CP. In addition, CP catalyzed the incorporation of Fe(II) into apoferritin. Collectively these data suggest that CP inhibits superoxide and ferritin-dependent lipid peroxidation via its ability to incorporate reductively-mobilized iron into ferritin.

Animals↗
PubMed1991

Simplified PCR-based detection and typing strategy for human papillomaviruses utilizing a single oligonucleotide primer set.

Utilizing the PCR, we have devised a detection and typing system for the human papillomaviruses (HPVs) that are commonly associated with preneoplastic and cancerous lesions of the genital and aero-digestive tracts: HPV 6, 11, 16 and 18. Utilizing computer sequence analysis, we designed a single, "consensus" set of oligomeric nucleotide primers capable of amplifying a 571-594-bp region of the E1 open reading frame of all of these HPVs. Detection via PCR amplification is followed by restriction endonuclease digestion of the resultant products that yield distinctive and reproducible banding patterns by polyacrylamide gel electrophoresis because of their internal sequence diversity. The system is sensitive, does not require sophisticated molecular biology expertise or radioisotopes and can be modified as new information on HPV types and their relationship to diseases becomes available.

Electrophoresis, Agar Gel↗
PubMed1991

Effect of pharmacy-conducted education on prescribing of postoperative narcotics.

The effect of written guidelines and pharmacist-conducted education on the prescribing of postoperative narcotics was studied. The postoperative narcotic regimens prescribed on a general surgery ward and patients' assessment of pain control were recorded during three eight-week study phases. After the first (baseline) phase, written guidelines for the use of postoperative narcotics were mailed to all physicians. Four weeks after the baseline phase ended, data were collected again for eight weeks. A pharmacist then began reinforcing the guidelines by presenting inservice educational sessions and participating in ward rounds. The pharmacist did not attempt to change narcotic regimens for individual patients. Four weeks after the pharmacist's efforts began, the final eight-week data-collection period commenced. In general, the appropriateness of narcotic orders increased as the educational efforts intensified. There was no difference in narcotic expenses or pain control among the study phases. The appropriateness of postoperative analgesic regimens increased as education efforts became more intense, but the efforts had no effect on drug expenses or pain control.

Drug Prescriptions↗
PubMed1991

A quality-control program for colposcopic practice.

Quality control is accepted as an integral part of the cytology laboratory's activities. However, provision of similar safeguards for colposcopic practice in assessing patients with abnormal cervical cytology has been an elusive problem. This report describes the quality-control program for colposcopy that is used province-wide in British Columbia for 21 hospital-based clinics staffed by 35 colposcopists. Copies of the results of all colposcopic examinations performed are sent to the Central Cytology Laboratory where the program is coordinated and the data are collated, analyzed, and evaluated. These data are used to set standards against which each colposcopist's performance and activity can be measured. One of the quality-control indicators used is a comparison between the colposcopic impression of the lesion and the corresponding direct biopsy diagnosis. Correlation within one histologic degree occurred in 86% of patients examined; this information was used to set a performance standard of 80% as the quality-control index for this particular indicator. Three colposcopists had scores below this standard. Comparisons were also made between presenting cytology, directed biopsy results, initial colposcopic impression, and final colposcopic evaluation (the clinical working diagnosis). The other major aspect of the quality-control program consists of an analysis of all cases of diagnosed invasive cervical cancer in the province in a given year to determine whether any colposcopically related errors occurred in the investigation and management of these cases. This system helps to identify individuals who may benefit from additional training.

Biopsy↗
PubMed1990

Effects of glycyl-histidyl-lysyl chelated Cu(II) on ferritin dependent lipid peroxidation.

The copper binding tripeptide, glycyl-L-histidyl-L-lysine [GHK:Cu(II)] has a plethora of biological effects related to the wound healing process. The presence of iron complexes in damaged tissues is detrimental to wound healing, due to local inflammation, as well as microbial infection mediated by iron. To test if the wound healing properties of GHK:Cu(II) are due to an affect on iron metabolism, we examined the effects of GHK:Cu(II) on iron catalyzed lipid peroxidation. GHK:Cu(II) inhibited lipid peroxidation only if the iron source was ferritin. Whereas GHK:Cu(II) inhibited ferritin iron release it did not exhibit significant superoxide dismutase-like or ceruloplasmin-like activity. We propose that GHK:Cu(II) binds to the channels of ferritin involved in iron release and physically prevents the release of Fe(II). Thus, a biological effect of GHK:Cu(II), possibly related to wound healing, may be the inhibition of ferritin iron release in damaged tissues, preventing inflammation and microbial infections.

Animals↗
PubMed1990

Oncogene alterations in endometrial carcinoma.

The neu oncogene codes for a cell surface protein that has a high degree of homology with the epidermal growth factor receptor. Amplification of this oncogene in breast carcinoma and ovarian carcinoma is correlated with a poorer prognosis. The c-myc oncogene codes for a DNA binding protein and is believed to regulate cellular proliferation. Sixteen primary endometrial adenocarcinomas were analyzed for c-myc and c-neu amplification. Eleven of sixteen tumor samples exhibited amplification of the neu gene. Four of these eleven patients died of disease an average of 16 months after diagnosis. The five patients without tumor amplification of the c-neu gene have been followed an average of 31.2 months without evidence of recurrent disease. Ten of fifteen tumor samples exhibited amplification of the c-myc gene. Five of the ten patients died of disease an average of 13.4 months after diagnosis. The remaining five patients have been followed for an average of 31.2 months and are free of disease. Six of the sixteen tumor specimens exhibited amplification of the both c-neu and c-myc genes, and four of these patients died of recurrent disease. Amplification of the c-neu or c-myc oncogene correlated with advanced-stage disease and poorly differentiated lesions, suggesting that oncogene amplification may predict biologically aggressive adenocarcinomas of the endometrium.

Adenocarcinoma↗
PubMed1990

Transition metals as catalysts of "autoxidation" reactions.

Superoxide (O2-), hydrogen peroxide (H2O2), and hydroxyl radical (.OH) produced from the "autoxidation" of biomolecules, such as ascorbate, catecholamines, or thiols, have been implicated in numerous toxicities. However, the direct reaction of dioxygen with the vast majority of biomolecules, including those listed above, is spin forbidden, a condition which imposes a severe kinetic limitation on this reaction pathway. Therefore, an alternate mechanism must be invoked to explain the "autoxidations" reactions frequently reported. Transition metals are efficient catalysts of redox reactions and their reactions with dioxygen are not spin restricted. Therefore it is likely that the "autoxidation" observed for many biomolecules is, in fact, metal catalyzed. In this paper we discuss: 1) the quantum mechanic, thermodynamic, and kinetic aspects of the reactions of dioxygen with biomolecules; 2) the involvement of transition metals in biomolecule oxidation; and 3) the biological implications of metal catalyzed oxidations. We hypothesize that true autoxidation of biomolecules does not occur in biological systems, instead the "autoxidation" of biomolecules is the result of transition metals bound by the biomolecules.

Animals↗
PubMed1990

Early detection of "rebreathing" in afferent and efferent reservoir breathing systems using capnography.

Capnography was used to determine the onset of rebreathing in afferent (AR) and efferent (ER) reservoir breathing systems in a spontaneous ventilation lung model. In the case of the Lack and enclosed AR systems, the best sampling site was found to be in the exhaust limb of the systems, 5 cm from the Y connector. For the Magill system, fitted with a hooded scavenging valve, the best site was deep inside the hooded valve. In contrast, the best sampling site in an ER system (e.g. Bain system) was in the tracheal tube. For AR systems, the loss of a fresh gas elimination pattern (carbon dioxide trace failing to reach zero) was shown to occur at the onset of rebreathing. As the sampling site was moved distally into the exhaust limb, the same pattern was seen at greater flow rates--that is, before rebreathing was actually occurring. When sampling was within the tracheal tube, using ER systems, a typical "rebreathing wave" occurred at the onset of established rebreathing.

Anesthesia, Inhalation↗
PubMed1990

DNA isolation and Southern analysis: a clinician's view.

DNA isolation and Southern Blot analysis are two of the many techniques currently being used routinely by molecular biologists to discover genetic defects that affect human health. Together these two techniques have greatly aided in the growing knowledge of genetics on a molecular level. Southern blotting can be used to discern genetic deletions, alterations, or amplifications that are not detectable by cytogenetic methods. Several examples of the clinical applications of these methods are discussed in Table 4. Southern analysis has been recently used: (1) to facilitate prenatal diagnosis of sickle cell hemoglobinopathies, (2) to demonstrate human papillomavirus DNA integration in the genome of cervical cancer cells and (3) to demonstrate that oncogene amplification in the tumors of patients with node positive breast cancer correlates inversely with prognosis. Each of these examples not only have diagnostic value for patient care but also may help begin to understand the very basis of the disease processes themselves.

Blotting, Southern↗
PubMed1990

Oncogenes, malignant transformation, and modern medicine.

During the past decade there have been remarkable strides in the understanding of the basic mechanism of cancer. It is now clear that there is a set of genes, known as oncogenes, that can cause cells to become malignant if their expression is altered, either by mutation or overexpression. The products of these genes include growth factors, growth factor receptors, signal tranduction proteins, and DNA binding proteins. The normal cellular counterparts of these genes play very important roles in the regulation of growth and proliferation by normal cells. Another set of genes, anti-oncogenes, also play an important role in preventing abnormal cell proliferation. The remarkable explosion of understanding of the pathophysiology of malignancy has led to a common unifying concept of malignant transformation that applies to all tumors. It is likely that these new insights will lead to improved and more specific treatments for malignant disease in the next decade.

Animals↗
PubMed1990

Mithramycin selectively inhibits the transcriptional activity of a transfected human c-myc gene.

The G-C specific DNA binding drug mithramycin selectively inhibits expression of the c-myc gene in a number of cell types. We have tested the ability of this agent to inhibit the expression of a transfected human c-myc gene in a murine fibroblast cell line. Expression of c-myc is inhibited in the first 24 hours of mithramycin exposure (in contrast to actin gene expression, which is unaffected). Nuclear runon transcription of c-myc by nuclei isolated from mithramycin treated cells is decreased, indicating inhibition of transcription initiation. However, treatment of isolated nuclei with mithramycin also results in decreased c-myc transcription. Thus, inhibition of c-myc expression by mithramycin in these cells appears to occur at the transcriptional level and is most likely mediated at both the transcription initiation and elongation level. This suggests that mithramycin selectively interacts with the G-C rich c-myc promoter, preventing formation of the c-myc transcription initiation complex.

Animals↗
PubMed1990

Characterization of 5B12.1, a monoclonal antibody specific for IL-6.

A monoclonal antibody (MAb) specific for interleukin-6 (IL-6) was generated by fusing SP2/0 cells with spleen cells from a mouse immunized with rat spleen cell derived plasmacytoma growth factor (rat PCT-GF). This MAb inhibited the growth of an IL-6-sensitive murine plasmacytoma clone, MD90, in the presence of the immunogen, rat PCT-GF. More interesting, however, this MAb demonstrated species cross-reactivity by neutralizing murine (recombinant and P388D1 cell line-derived) and human (recombinant) IL-6. IL-6 neutralization activity was also established in other IL-6 bioassays, such as the proliferation of spleen cells, plasmacytoma T1165, and a B-cell hybridoma 7TD1. IL-6 neutralization was overcome partially by increasing the concentration of PCT-GF. The MAb had no effect on PCT-GF-independent plasmacytoma KI81 proliferation. Plastic petri dish-bound MAb removed rmIL-6 activity. These results suggest that this MAb specifically binds IL-6 and neutralizes bioactivity of various PCT-GF, rmIL-6, and rhIL-6.

Animals↗
PubMed1990

NMR and fluorometric characterization of mithramycin in aqueous solution.

The assignments for the resonances in the 1H and 13C NMR spectra of mithramycin in aqueous solution have been determined by a combination of 2D NMR methods. Specific NOESY contacts observed between different moieties indicate that the drug assumes a compact conformation in aqueous solution. Fluorescence measurements are consistent with a compact structure for mithramycin in water and confirm the preference of mithramycin for binding to dG-containing nucleic acids. These studies provide a basis for the further physico-chemical characterization of mithramycin-DNA complexes.

DNA↗
PubMed1990

Stimulation of renal and hepatic c-myc and c-Ha-ras expression by unilateral nephrectomy.

Unilateral nephrectomy induces compensatory hypertrophy of the contralateral kidney in rats, resulting in a 25% weight increase in 14 days. We have demonstrated that expression of the c-myc and c-Ha-ras protooncogenes is increased more than ten-fold in the contralateral kidney within 4 to 8 hr following unilateral nephrectomy in rats. The increased expression of these genes is analogous to the increased expression of c-myc and c-Ha-ras that occurs early in liver regeneration, preceding the first increase in DNA synthesis by at least 20 hr. In order to define the tissue specificity of the signals for compensatory renal hypertrophy, we also determined the early protooncogene response and the proliferative response in the liver of rats following unilateral nephrectomy. The expression of c-myc and c-Ha-ras was also increased (five- to ten-fold) in the livers of these animals. DNA synthesis was stimulated in the contralateral kidney at 26-30 hr following nephrectomy as measured by 3H thymidine incorporation, indicating a hyperplastic response to unilateral nephrectomy. However, there was no increase in DNA synthesis in the liver despite the dramatic increase in c-myc and c-Ha-ras expression. Our data suggest that the early increase in protooncogene expression in response to unilateral nephrectomy is stimulated by circulating signals that are not tissue-specific. Increased protooncogene expression in both kidney and liver following unilateral nephrectomy is an early response to the regenerative stimulus, but later signals must provide the tissue specificity necessary for regeneration and cellular proliferation.

Animals↗