PubMed Health⌕ Search

Biomedical subjects

P W Brandt-Rauf

Publications and source records attributed to P W Brandt-Rauf.

At least 55 records · Page 3Linked to original sources
PubMed1994

Detection of serum p53 protein in lung cancer patients.

Serum levels of p53 protein were examined in 23 cases of lung cancer (many with potential asbestos exposure), 23 unexposed matched hospital control subjects, 58 unmatched general population control subjects, and 4 people with nonmalignant lung disease using an enzyme-linked immunosorbent assay and Western immunoblotting. Average levels of serum p53 in the lung cancer patients (0.55 ng/mL) were higher than in the cases of nonmalignant lung disease (0.42 ng/mL) or in the matched (0.32 ng/mL) or unmatched (0.31 ng/mL) control subjects, but the differences were not statistically significant. However, three of the cases of lung cancer (13%) were found to have serum p53 levels much greater than those of the control subjects (> 2 SD above the mean) and to have confirmatory positive Western blots for p53. The tumors from these subjects demonstrated increased levels of p53 in the tissue by immunohistochemistry and/or the presence of mutations in the p53 gene. These results suggest that p53 protein can be detected in serum in a portion of lung cancer cases with p53 alterations in the tumor tissue.

Aged↗
PubMed1994

The detection of increased amounts of the extracellular domain of the epidermal growth factor receptor in serum during carcinogenesis in asbestosis patients.

Overexpression of the epidermal growth factor receptor (EGFr) has been implicated in the pathogenesis of a wide variety of human malignancies and may be related to asbestos-induced carcinogenesis. Overexpression of the EGFr can be detected immunologically by quantitation of the extracellular domain (ECD) in the extracellular fluid in vitro and in serum in vivo. An enzyme-linked immunosorbent assay (ELISA) for the EGFr ECD was used to examine banked serum samples of 38 asbestosis patients who subsequently developed cancer, 72 age-sex-race-smoking-asbestos exposure matched asbestosis controls without cancer, and 20 age-sex-race-smoking matched nonasbestosis noncancer controls. The mean serum level for the EGFr ECD in the cancer cases (636 +/- 299 fmol/ml) was statistically significantly elevated (P < 0.05) in comparison to the mean level in the asbestosis controls (546 +/- 147 fmol/ml) or the nonasbestosis controls (336 +/- 228 fmol/ml). Defining a positive elevation of the serum EGFr ECD as any value more than 2 standard deviations above the nonasbestosis control mean, 7 (18%) of the cancer cases were positive compared to 4 (6%) of the asbestosis controls and one (5%) of the nonasbestosis controls. In addition, all of these cancer cases had positive serum samples prior to the time of disease diagnosis (average = 5.1 years). These results suggest that serum EGFr ECD may be elevated at an early stage of carcinogenesis in some asbestosis patients and that further prospective study of the utility of this biomarker is warranted.

Adult↗
PubMed1994

The c-erbB-2 protein in oncogenesis: molecular structure to molecular epidemiology.

The c-erbB-2 (HER-2, neu) oncogene has been implicated frequently in many human tumors. This oncogene codes for a 185-kDa protein that functions as a transmembrane growth factor receptor. Overexpression of the normal protein or point mutations in the transmembrane domain of the protein have been shown to have a transforming effect. Molecular structure studies of the transmembrane domain provide a plausible explanation for this transforming effect in both cases and relate this to the process of receptor dimerization in the membrane, degradation of the protein with release of the extracellular domain (ECD) into the extracellular environment, and aberrant signal transduction. The release of the ECD into the extracellular environment provides a potential biomarker for the study of signal transduction at the molecular level in vivo. The ECD can be quantitated immunologically in the serum of individuals with cancers associated with p185 overexpression and in individuals at risk for the development of such cancers and can be used to distinguish these individuals from normal, healthy controls. Identification of such individuals by their serum ECD levels combined with specific chemotherapeutic/chemoprophylactic interventions could allow for improvement treatment and prevention of c-erbB-2-related cancers.

Amino Acid Sequence↗
PubMed1993

A comparison of techniques for introducing macromolecules into living cells.

Flow cytometry has been used to evaluate several techniques for introducing macromolecules into large numbers of living cells. One technique is cell fusion with red blood cell ghosts loaded with a fluorescent reporter molecule (RBCF). The second technique, termed osmotic lysis of pinosomes (OLP), involves a brief exposure of cells to a hypertonic solution containing the reporter molecule; subsequently, a hypotonic media is added which lyses the pinosomes formed during the hypertonic treatment. A third technique, scrape loading (SL), involves the creation of transient holes in the cell membrane through the application of mechanical forces, which allows for the passage of reporter molecules into cells. A comparison of these techniques is presented here. OLP appears to offer several advantages: It is a simple procedure, virtually all cells are fluorescently labelled, and it is capable of loading larger amounts of material more uniformly into cells while maintaining excellent viability.

Cell Fusion↗
PubMed1993

Molecular dynamics of the H-ras gene-encoded p21 protein; identification of flexible regions and possible effector domains.

We previously reported a complete computer-based three-dimensional structure for residues 1-171 of the Gly 12-containing ras-gene-encoded p21 protein complexed with GDP. This structure was subsequently shown to closely agree with a high-resolution x-ray crystallographic structure of p21. In this communication, we report a molecular dynamics stimulation of the modelled structure in an explicit shell of water molecules to identify domains within the protein that are unusually flexible. These domains represent regions which are most likely to undergo important conformational changes when the protein is activated by binding to GTP or by oncogenic amino acid substitutions such as Val for Gly 12. The starting structure was surrounded with water molecules, temperature-equilibrated and then followed over a 100 ps trajectory during which time the energy converged after about 50 ps. Regions of the protein that were found to have the largest coordinate fluctuations involved residues 12-16, 30-35, 40-52, 60-73, 85-89, 101-109, 119-123, and 127-131. Many of these sequences with high flexibility have been implicated in the functioning of this protein. Since the overall largest fluctuations were observed for residues 101-106 and 119-123, p21 peptides containing these residues (96-110 and 115-126) were synthesized and were found to inhibit strongly the effects of oncogenic p21 protein in an oocyte maturation assay. These results indicate that the flexible p21 sequences may constitute critical functional domains of the activated protein and that this general approach may be useful for identification of important functional domains in proteins.

3T3 Cells↗
PubMed1993

A nickel-binding serpin, pNiXa, induces maturation of Xenopus oocytes and shows synergism with oncogenic ras-p21 protein.

A nickel-binding serine proteinase inhibitor, pNiXa (43 kDa), was isolated from Xenopus ovary and assayed for effects on oocyte maturation. Microinjection of pNiXa (0.12 pmol/50 nl) induced maturation in 60% of Xenopus oocytes, beginning at 4 hours and reaching completion by 9 hours. Microinjection of oncogenic ras-p21 protein (0.12 pmol/50 nl) induced maturation in 79% of oocytes, beginning at 6 hours and reaching completion by 12 hours. Microinjection of pNiXa in combination with ras-p21 protein had a synergistic effect on maturation, which occurred in 92% of oocytes, beginning at 4 hours and reaching completion by 9 hours. Oocyte maturation did not occur in control oocytes, which received a microinjection of bovine serum albumin. In oocytes exposed to a combination of pNiXa (0.12 pmol/50 nl, by microinjection) and progesterone (10 micrograms/ml, in the medium), maturation was intermediate (68% at 9 hours) between that induced by pNiXa (60%) or progesterone (85%) alone. This study shows (a) that pNiXa is a potent inducer of oocyte maturation, (b) that pNiXa's effect is synergistic with that of oncogenic ras-p21 protein, and (c) that pNiXa partially antagonizes progesterone induction of oocyte maturation.

Animals↗
PubMed1992

Serum oncoproteins and growth factors in asbestosis and silicosis patients.

Levels of 9 different oncoproteins and growth factors were assayed by immunoblotting with monoclonal antibodies in 91 serum samples collected between March 1983 and August 1987 from 46 pneumoconiosis patients (36 asbestosis, 10 silicosis) at high risk for the development of cancer. Follow-up of these patients through June 1991 showed that 18 had developed cancer (11 lung, 2 pleural mesothelioma, 2 transitional-cell carcinomas of the urinary bladder, 1 osteosarcoma, 1 non-Hodgkin's lymphoma, 1 adenocarcinoma of the gallbladder). Increased serum levels of ras oncogene-related protein (p21) were found in 7 of the 18 patients who developed cancer (5 lung, 2 pleural mesothelioma) versus 2 of the 28 patients without cancer, a statistically significant difference (p = 0.012). In addition, 6 of the 7 p21-positive cancer cases had positive serum samples prior to clinical diagnosis of disease (average = 16.3 months, range = 3-26 months prior to diagnosis), suggesting that elevated serum p21 levels may be a useful marker for earlier detection in a significant percentage of respiratory malignancies. Finally, elevated serum levels of PDGF-related protein were detected significantly more frequently in advanced pneumoconiosis cases (ILO radiographic classification of 2/1 or greater) than in less advanced cases (80% vs. 41.9%; p = 0.016), and there was a tendency for these PDGF-positive patients to have progression of their disease (68.2% vs. 41.7%; p = 0.065), suggesting that elevated serum PDGF levels may be a marker for the development of severe and progressive pneumoconioses.

Aged↗
PubMed1992

Evidence that the ras oncogene-encoded p21 protein induces oocyte maturation via activation of protein kinase C.

The ras oncogene-encoded p21 protein is known to induce cell maturation of Xenopus laevis oocytes and malignant transformation of NIH 3T3 mouse fibroblasts. The pathways involved in oocytes and NIH 3T3 cells appear to be similar to one another. For example, in both cases, the ras p21-induced cellular events involve increased intracellular levels of the second messengers diacylglycerol and inositol phosphates, the former of which activates protein kinase C (PKC). To investigate the pathway of ras-induced oocyte maturation, we have explored the relationship between p21 protein and PKC. We show that the maturation signal from oncogenic p21 microinjected into Xenopus oocytes is completely blocked by the relatively specific PKC inhibitor CGP 41251, a staurosporine analogue that selectively inhibits PKC, but not by an inactive analogue of staurosporine, CGP 42700. Microinjection of purified PKC or of phorbol ester induces maturation of oocytes. PKC-induced maturation is inhibited by CGP 41251 but not by CGP 42700. Maturation induced by microinjected PKC is also not inhibited by two specific anti-p21 agents, the inactivating anti-p21 monoclonal antibody Y13-259 and the amino acid derivative azatyrosine. Both of these agents block p21-induced cell maturation. These results suggest that ras effects depend upon the action of PKC, whose activation is an event that occurs downstream of p21 in the maturation signal pathway.

Alanine↗
PubMed1992

Evidence that oocyte maturation induced by an oncogenic ras-p21 protein and insulin is mediated by overlapping yet distinct mechanisms.

We have recently shown that a peptide (residues 35-47) from a functional region of the ras p21 protein, thought to be involved in the binding of p21 to GTPase activating protein, the antibiotic azatyrosine, known to induce the ras-recision gene, and the selective protein kinase C inhibitor, CGP 41,251, all inhibit oncogenic p21 protein-induced maturation of oocytes in a dose-dependent manner. We now show that these three agents only partially inhibit insulin-induced oocyte maturation, known to be dependent on activation of cellular p21 protein. On the other hand, the anti-p21 protein antibody Y13-259 completely inhibits both insulin- and oncogenic p21 protein-induced maturation as does a tetrapeptide, CVIM, known to block the enzyme farnesyl transferase which covalently attaches the farnesyl moiety to the p21 protein allowing it to attach to the cell membrane. Our results suggest that while the oncogenic and insulin-activated normal p21 proteins share certain elements of their signal transduction pathways in common, these pathways diverge and allow for selective inhibition of the oncogenic pathway.

Alanine↗
PubMed1992

Conformational effects of selected cancer-related amino acid substitutions in the p53 protein.

The tumor suppressor gene p53 has been identified as the most frequent target of genetic alterations in human cancers. Cancer-related mutations in the human p53 protein tend to cluster in four of the five highly conserved domains of the protein, and, in particular, in the central region of domain IV from residues 241 to 253. Using conformational energy analysis based on ECEPP (Empirical Conformational Energies for Polypeptides Program), we have determined the preferred three dimensional structures for this tridecapeptide sequence for the human wild-type p53 protein and four cancer-related mutant p53 proteins (Ala 245, Ile 246, Trp 248, Ser 249). The results show that the mutant peptides adopt conformations that are distinctly different from that of the wild-type peptide. These results are consistent with experimental conformational studies demonstrating altered detectability of antigenic epitopes in murine wild-type and mutant p53 proteins. These results suggest that the oncogenic effects of human mutant p53 proteins may be mediated by distinct local conformational changes in the protein.

Amino Acid Sequence↗
PubMed1992

Oncogenes and oncoproteins in occupational carcinogenesis.

It seems increasingly likely that an important mechanism of action of certain workplace carcinogens in contributing to occupational carcinogenesis may be via the activation of cellular oncogenes, which then cause an expression of mutated forms or increased amounts of their oncoprotein products. Two prototypical models of this mechanism may be the ras oncogene and its p21 protein and the neu oncogene and its p185 protein. Both are known to be activated by exposure to common occupational carcinogens, and both are known to occur frequently in human tumors, including those of occupational concern such as lung cancer. Knowledge of their mechanisms of action may lead to new opportunities for preventing occupational cancer.

Animals↗
PubMed1992

The molecular epidemiology of oncoproteins.

Oncogene activation, which appears to play a critical role in carcinogenesis, can be conveniently studied in biological samples via immunologic detection of oncoprotein products with monoclonal antibodies. Immunohistochemical and immunocytochemical detection of oncoproteins can be used to differentiate normal cells from cancer cells, including those of cancers of occupational concern such as lung, bladder, and liver. Furthermore, oncoproteins appear to reach the extracellular environment and are detectable with immunoblotting techniques in the urine and serum of cancer patients. Similar techniques applied to the screening of sera of occupational cohorts with carcinogen exposures indicate that oncoproteins can be detected in workers at increased risk of the development of cancer, and thus oncoprotein detection may be a useful molecular epidemiologic biomarker of preclinical response for the surveillance and prevention of occupational cancer.

Biomarkers, Tumor↗
PubMed1991

Oncogene proteins as biomarkers in the molecular epidemiology of occupational carcinogenesis. The example of the ras oncogene-encoded p21 protein.

The use of oncogene proteins as biomarkers offers a new approach to the molecular epidemiologic evaluation of occupational carcinogenesis. The ras oncogene-encoded p21 protein represents a prototype for this type of study, since it is known to be activated by common occupational carcinogens, is frequently found in human tumors of occupational concern, and, at least in certain instances, appears to be expressed relatively early in the disease process, allowing the possibility of early detection and intervention. Herein, we review our experience with the use of immunologic detection of p21 in cohorts with cancer or at risk for the development of cancer due to their occupational exposures. The results suggest that p21 (particularly when used with other oncoproteins and biomarkers such as PAH-DNA adducts) will indeed be a useful addition to the growing armamentarium of molecular epidemiologic biomarkers in the study of occupational carcinogenic mechanisms and in the detection and prevention of occupational cancers.

Biomarkers, Tumor↗
PubMed1991

An activating amino acid substitution in the c-abl oncogene protein fails to produce a local conformational change.

The bcr-abl chimeric gene of Philadelphia chromosome positive chronic myelogenous leukemias is only weakly transforming. This transformation activity is greatly enhanced by a Lys-for-Glu substitution at position 832 in the c-abl gene, as occurs in the highly transforming v-abl genes. It has been suggested that this mutation results in a significant structural change in the encoded protein product. Using conformational energy analysis, we have determined the allowed low-energy conformations for residues 828-836 of this protein with Lys and Glu at position 832. In both cases, the overwhelmingly preferred conformation for this region is a bend-helix motif. The helix terminates at residue 836, and there are no discernible differences in conformation between the Lys- and Glu-containing sequences. These results suggest that the activating amino acid substitution at position 832 in the c-abl protein product does not produce its effect via a local conformational change.

Amino Acid Sequence↗
PubMed1991

Sick-hospital syndrome.

An outbreak of complaints consisting primarily of eye and respiratory tract irritation accompanied by headache, dizziness, fatigue, and nausea occurred among the operating room personnel of a large metropolitan hospital. This initially was attributed to infiltration of diesel exhaust emissions into the ventilation system. However, following correction of this problem and subsequent unrevealing air monitoring, symptoms persisted and were noted in personnel in adjacent areas of the hospital as well. An industrial hygiene and medical evaluation was undertaken. Monitoring for carbon monoxide, formaldehyde, and anesthetic gases and review of medical records and patient examinations were unrevealing, and the problem resolved gradually over several weeks. This outbreak represents a case of building-associated illness among health professionals in a hospital setting that was triggered by a single, identifiable noxious exposure but was sustained despite any apparent ongoing noxious exposures.

Air Pollutants↗
PubMed1991

Advances in cancer biomarkers as applied to chemical exposures: the ras oncogene and p21 protein and pulmonary carcinogenesis.

Pulmonary carcinogenesis due to occupational and environmental exposures to chemical carcinogens such as polycyclic aromatic hydrocarbons presents an interesting model for study of possible oncogene-related cancer biomarkers. Polycyclic aromatic hydrocarbons are important respiratory carcinogens and have been shown to cause specific mutational lesions that can lead to the activation of the ras oncogene and expression of its p21 protein product; ras oncogene activation and p21 expression frequently are detected in human lung cancers. In addition, the p21 protein is detectable via immunoblotting techniques in the serum of lung cancer patients and in selected persons in exposed worker cohorts at risk for the development of lung cancer. Thus, the ras oncogene and p21 protein may be useful biomarkers for monitoring pulmonary carcinogenesis in exposed populations.

Biomarkers, Tumor↗