Genome studies and molecular genetics plant biotechnology
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
D Dixon
Publications and source records attributed to D Dixon.
Physiology and metabolism
Explore the source record for details and available documents.
Journal Article↗
Growth and development
Explore the source record for details and available documents.
Journal Article↗
Analysis of genetic alterations in uterine leiomyomas and leiomyosarcomas by comparative genomic hybridization.
Uterine leiomyomas are the most prevalent tumor type in women of reproductive age and are the most common reason for hysterectomies. Although uterine leiomyomas are considered to be benign, they are a major public health concern for women. In contrast, leiomyosarcomas are rare but highly malignant uterine tumors. They may arise in uteri with preexisting leiomyomas and histologically sometimes resemble leiomyomas, thus causing controversy about whether leiomyosarcomas arise within leiomyomas. In this study, we used comparative genomic hybridization (CGH) to identify genetic alterations unique to each tumor type and alterations that are common between the two tumors. We analyzed 14 cases of uterine leiomyomas and eight cases of uterine leiomyosarcomas. Only two of the 14 leiomyomas exhibited genetic alterations, and those were restricted to gains on chromosomes 14 and 19 and losses on chromosomes 1 and 4. In addition, 68 leiomyomas were examined for loss of heterozygosity on chromosomes 1 and 4, and only three tumors exhibited any losses. In contrast, all eight leiomyosarcomas showed gains and losses of DNA by CGH, and in many cases multiple changes were observed. The most commonly observed genetic aberration, occurring in five tumors, was gains on both arms of chromosome 1, suggesting that this chromosome contains loci involved in the development of leiomyosarcoma. Our results do not provide evidence for the progression from benign leiomyoma to malignant leiomyosarcoma. Moreover, the large number of random chromosomal alterations in the leiomyosarcomas suggests that increased genetic instability plays a role in the formation of these tumors.
Chromosome Aberrations↗
Specificity of antibodies against rodent transforming growth factor-alpha protein.
We found that the immunohistochemical distribution of TGF-alpha varied in rodent tissues depending on the antibody used, suggesting that the specificity of anti-TGF-alpha antibodies differs significantly. To address this issue, we compared the specificity of two representative antibodies that have been widely used to detect rodent TGF-alpha. In a competition study, the antibodies were preincubated with an excess of synthetic rat TGF-alpha 34-50 and were used for staining of rat and mouse kidneys and/or uterus. The results revealed that one of the antibodies, anti-rat TGF-alpha polyclonal antibody, was neutralized by the peptide, whereas the other, anti-human TGF-alpha monoclonal antibody, was not absorbed by the peptide up to an excess of 100-fold. Western blotting analysis showed that the anti-rat TGF-alpha polyclonal antibody recognized both human and rat purified TGF-alpha. However, the anti-human TGF-alpha monoclonal antibody did not detect purified rat TGF-alpha, although the antibody reacted with mouse proteins other than TGF-alpha from kidneys and uterus, purified human TGF-alpha, and mouse carbonic anhydrase II. These data indicate that the anti-human TGF-alpha monoclonal antibody does not recognize rodent TGF-alpha under our experimental conditions and suggest that distribution of TGF-alpha in rodent tissues may need to be reexamined.
Animals↗
Dissociation characteristics of endothelin receptor agonists and antagonists in cloned human type-B endothelin receptor.
The human type-B endothelin receptor (h-ETB) was cloned from human lung poly A+RNA and stably expressed in CHO cells. Endothelin (ET) receptor binding and stimulation of PI hydrolysis demonstrated that the cloned h-ETB receptor is functional and linked to intracellular signal transduction pathways in CHO cells. The molecular mass of the h-ETB receptor was determined to be 65 KDa, and Bmax and Kd were 0.36 pmol/mg and 80 pM, respectively. Competition studies employing receptor ligands revealed that the potencies of the test ligands (IRL1620, PD142893, and Ro46-2005) were dependent on the length of the incubation time, whereas the natural agonists (ET-1 and ET-3) were not. When competing with ET-1 in the h-ETB receptor binding, the IC50 increased from 1.2 nM to 8.2 nM for IRL1620, 0.068 microM to 1.9 microM for PD142893, and 0.76 microM to 12.7 microM for Ro46-2005, as the incubation time increased from 1 hr to 24 hr. These time-induced changes are likely due to differences in the dissociation characteristics between the artificial ligands and the natural ligands.
Animals↗
Influence of energy level alignment on tunneling between coupled quantum dots.
Explore the source record for details and available documents.
Journal Article↗
Altered regulation of surfactant phospholipid and protein A during acute pulmonary inflammation.
Biochemical changes in the pulmonary surfactant system caused by exposure to toxicants are often accompanied by an influx of inflammatory cells into the lungs. We have investigated the possibility that the inflammatory and surfactant biochemical effects might be connected. Co-treatment with dexamethasone, a synthetic anti-inflammatory glucocorticoid, mitigated the increases in free cells and total intracellular surfactant phospholipid normally seen in animals given silica alone, suggesting a relationship between the free cell population of the alveoli and the surfactant system during alveolitis. Furthermore, we have investigated whether induction of the surfactant system is a universal response to alveolar inflammation. Inflammation was induced in the lungs by intratracheal injections of titanium dioxide, silica, bleomycin or lipopolysaccharide (LPS) suspended in isotonic saline. Inflammatory cell and surfactant responses were measured at 3 days and 14 days following injection. There was a distinct alveolar inflammatory cell profile following administration of each agent, at each time point, indicating a dynamic inflammatory cell population during the course of the study. Furthermore, surfactant phospholipid and protein A (SP-A) pools exhibited unique responses to the inflammatory agents. Only silica-treated lungs maintained elevated levels of surfactant phospholipids and SP-A throughout the course of the experiment. We conclude that both the surfactant components and the inflammatory cell population of the alveoli undergo dynamic changes following treatment with these inflammatory agents and that activation of the surfactant system is not a universal response to alveolar inflammation, since surfactant components were not always elevated during times of increased alveolar cellularity. The unique inflammatory cell infiltrate elicited by silica is of particular interest in that surfactant components were elevated throughout the course of the experiment in this group. Indeed, we have shown that the size of the intracellular pool of surfactant is directly proportional to the number of polymorphonuclear leukocytes but not alveolar macrophages or lymphocytes in the alveoli following silica treatment. Finally, our data suggest that the phospholipid and SP-A components of surfactant respond differentially to the pulmonary toxicants in this study.
Animals↗
Intrauterine therapy for homozygous alpha-thalassemia.
BACKGROUND: Alpha-thalassemia is one of the most common genetic disorders in the world and is becoming more common in the United States with the increase in immigration of susceptible populations. This disease has been stated previously to be incompatible with extrauterine life. CASE: A Filipino woman with a prior loss due to hemoglobin Bart's underwent prenatal diagnosis that confirmed recurrence in the index pregnancy. Intravascular intrauterine exchange transfusions maintained appropriate fetal growth. A cesarean delivery yielded a 2190-g male infant with minor malformations. The postnatal course was characterized by mild respiratory insufficiency. Postnatal chronic transfusion therapy is underway pending consideration for bone marrow transplantation. CONCLUSION: Antenatal diagnosis and therapy of homozygous alpha-thalassemia can prevent the prenatal consequences of hydrops and fetal death. New technologies such as stem cell transplantation may help to avert both prenatal and postnatal consequences.
Abnormalities, Multiple↗
Comparative and collaborative evaluation of standardization of antifungal susceptibility testing for filamentous fungi.
The purpose of the study was to evaluate the interlaboratory agreement of broth dilution susceptibility methods for five species of conidium-forming (size range, 2 to 7 microns) filamentous fungi. The methods used included both macro- and microdilution methods that were adaptations of the proposed reference method of the National Committee for Clinical Laboratory Standards for yeasts (m27-P). The MICs of amphotericin B, fluconazole, itraconazole, miconazole, and ketoconazole were determined in six centers by both macro- and microdilution tests for 25 isolates of Aspergillus flavus, Aspergillus fumigatus, Pseudallescheria boydii, Rhizopus arrhizus, and Sporothrix schenckii. All isolates produced clearly detectable growth within 1 to 4 days at 35 degrees C in the RPMI 1640 medium. Colony counts of 0.4 x 10(6) to 3.3 x 10(6) CFU/ml (mean, 1.4 x 10(6) CFU/ml) were demonstrated in 90% of the 148 inoculum preparations. Overall, good intralaboratory agreement was demonstrated with amphotericin B, fluconazole, and ketoconazole MICs (90 to 97%). The agreement was lower with itraconazole MICs (59 to 79% median). Interlaboratory reproducibility demonstrated similar results: 90 to 100% agreement with amphotericin B, fluconazole, miconazole, and ketoconazole MICs and 59 to 91% with itraconazole MICs. Among the species tested, the MICs for S. schenckii showed the highest variability. The results of the study imply that it may be possible to develop a reference method for antifungal susceptibility testing of filamentous fungi.
Aspergillus↗
Incorporation of bromodeoxyuridine (BrdU) in the bronchiolar-alveolar regions of the lungs following two inhalation exposures to chrysotile asbestos in strain A/J mice.
We have been studying early fibroproliferative events in the lungs of rodents exposed to aerosols of asbestos fibers. In the experiments presented here, incorporation of bromodeoxyuridine (BrdU) in the bronchiolar/alveolar (B/A) regions of the lungs in mice was assessed following two consecutive exposures to chrysotile asbestos. Six to 8-week-old male strain A/J mice, a strain with a high spontaneous incidence of B/A tumors, were exposed to inhaled asbestos fibers for two consecutive days (3 hours/day). A group of mice was also given an intraperitoneal injection of urethane, a known lung carcinogen in A/J mice, 48 h after initial inhalation exposure to asbestos. The groups of mice exposed to asbestos had significantly (p <0.05) increased incorporation of BrdU in the nuclei of epithelial and interstitial cells in the B/A regions of the lung at 48 h, 72 h, and 2 weeks after initial exposure. By 1 month, the labeling indices in mice exposed to asbestos were not statistically significantly different from the controls; however, in the regions of the first alveolar duct bifurcations (ALDB), the primary site of initial asbestos deposition, there continued to be detectable labeling of the epithelial and interstitial cells. Because of considerable variability from duct to duct, there were no statistically significant differences between the asbestos-exposed mice and control groups at 3 months. We conclude that in A/J mice the initial proliferative response observed in the B/A regions of the lung after two 3-h inhalation exposures to asbestos is significantly prolonged through 2 weeks post-exposure. In addition, there was measurable labeling above control values in the epithelial and interstitial cells of the first alveolar duct bifurcations up to 3 months after exposure. Urethane had no apparent effect on the incorporation of BrdU into any cells of the B/A regions of the lung when administered after inhalation exposure to asbestos. Furthermore, although the A/J strain is highly susceptible to lung tumor formation, the unexposed control A/J mice showed no spontaneous increases in cell proliferation.
Administration, Inhalation↗
Photon-assisted tunneling through a quantum dot.
Explore the source record for details and available documents.
Journal Article↗
Design and synthesis of novel cyclic RGD-containing peptides as highly potent and selective integrin alpha IIb beta 3 antagonists.
Utilizing conformational constraints in conjunction with various structural considerations, we have synthesized a series of cyclic disulfide peptides that are highly potent and selective antagonists for the platelet integrin alpha IIb beta 3 (GPIIb/IIIa). The affinities of the peptides for alpha IIb beta 3 were determined by platelet aggregation assays and an alpha IIb beta 3 ELISA. Their affinities for alpha 5 beta 1 and alpha v beta 5 integrins were also determined in respective ELISA assays. Structure-activity relationship studies suggest that R-G-D-Ar-R (Ar = hydrophobic residue) is the essential pharmacophore that is responsible for their high alpha IIb beta 3 binding affinity, very high selectivity, and distinct biological properties. One of these analogues, TP9201, has been shown to inhibit platelet-mediated thrombus formation without associated prolongation of template bleeding time. The arginine residue adjacent the carboxy terminus of the R-G-D-Ar sequence could function as the biological effector element that determines this distinct and unexpected biological property.
Amino Acid Sequence↗
Pulmonary response of Fischer 344 rats to acute nose-only inhalation of indium trichloride.
We have previously shown that rats dosed intratracheally with indium trichloride (InCl3) develop severe lung damage and fibrosis. However, it is not clear what pulmonary effects would result following accidental occupational exposure to low concentrations of indium by inhalation. The present study uses a model of acute lung injury based on single 1-hr nose-only exposures to 0.2, 2.0, or 20 mg InCl3/m3. Exposure to 0.2 mg InCl3/m3 was capable of initiating an inflammatory response. Seven days following inhalation of 20 mg InCl3/m3 the total cell number, fibronectin, and TNF alpha levels in the bronchial alveolar lavage fluid were 8, 40, and 5 times higher than the control, respectively. Commensurate with the level of lung injury 7 days after exposure, an acute restrictive lung lesion and increased airway responsiveness to acetylcholine were observed. Forty-two days after exposure a compensatory increase in lung volume and carbon monoxide diffusing capacity in the 20 mg InCl3/m3 group suggested recovery from the lung injury. Lung collagen levels were increased in a concentration-dependent manner 42 days postexposure. These data indicate that inhalation of InCl3/m3 causes acute inflammatory changes in the lung.
Administration, Inhalation↗
Pulmonary toxicity to intratracheally administered indium trichloride in Fischer 344 rats.
The use of indium by the semiconductor industry has risen sharply in recent years with the discovery that the electrical properties of compounds such as indium phosphide and indium arsenide are better than those of silicon. However, relatively little is known about its potential to induce lung damage. These studies examined the effect of indium trichloride (InCl3) on the lung. To examine the disposition and removal of InCl3 from the lung, groups of female Fischer 344 rats received a single intratracheal dose of 1.3 mg In/kg as InCl3 and were euthanized after 1, 2, 4, 7, 14, 28, and 56 days at which time lung samples were analyzed for metal content. Furthermore, the histology, hydroxyproline levels, and bronchoalveolar lavage (BAL) fluid cellularity of the lung were studied. In addition, the effect of 0.00016, 0.00325, 0.065, and 1.3 mg In/kg on inflammatory response and BAL fluid cellularity was compared. While a dose as low as 0.00325 mg In/kg was capable of initiating an influx of inflammatory cells, instillation of 1.3 mg In/kg resulted in an inflammatory response that was still evident 56 days later. After 28 days, the lung weight of the InCl3-treated animals was 2.5 times greater than that of the controls. The total cell number in the BAL fluid of the treated animals after 28 days was 32 times higher than that in the control rats. Sixty-seven percent of these cells were granulocytes. Compared to the controls, the hydroxyproline content of the lungs from the InCl3-treated animals were two-fold greater after 28 and 56 days. Furthermore, the levels of fibronectin and TNF alpha present in the BAL fluid of InCl3-treated rats increased sharply during the first 24 hr and remained elevated 56 days later. These data and the histological examination of the lung following InCl3 treatment suggest that InCl3 is capable of causing severe lung damage and the development of fibrosis.
Animals↗
Inhibition of lung immunity after intratracheal instillation of benzo(a)pyrene.
Benzo(a)pyrene (B(a)P) has been shown to suppress systemic immunity in experimental animals, which may contribute to the growth of the chemical-induced tumors. However, its effects on lung immunity after inhalation, a common route for human exposure in urban areas, has not been determined. These studies examine intratracheal B(a)P instillation on lung natural killer (NK) cell activity, alveolar macrophage (AM) functions, and susceptibility to tumor cell challenge in Fischer 344 (F-344) rats. Adult female F-344 rats were given a single intratracheal instillation of 0, 10, 20, or 40 mg B(a)P/kg body weight as a suspension, and lung NK cell activity and AM functions were examined 7, 21, or 100 d later. Although exposure to B(a)P did not alter cell recovery after lavage, histologic changes were observed as evidenced by granulomatous inflammation and squamous metaplasia. There was a slight but significant suppression of H2O2 and nitric oxide (NO) release from alveolar macrophages of treated animals as well as NK cell activity from the lung digest. A marked suppression of tumor necrosis factor-alpha (TNF alpha) and interleukin (IL-1) secretion in LPS- and/or cytokine-activated alveolar macrophages occurred. The suppressive effects were generally more severe on Day 7 after exposure than on Days 21 or 100, although IL-1 remained depressed through Day 100 after exposure. B(a)P exposure allowed for the increased growth of MADB106 metastatic tumor cells in the lung. These tumor cells were shown to be highly sensitive to lysis by immune-mediators, including TNF alpha.(ABSTRACT TRUNCATED AT 250 WORDS)
Adenocarcinoma↗
"Lipomatous" lesions of unknown cellular origin in the liver of B6C3F1 mice.
The gross, microscopic, and ultrastructural features of lipomatous lesions in the liver of B6C3F1 mice are described. The cases were selected from a database of 45,406 male and 45,674 female mice used as treated, control, or vehicle-control animals in the National Cancer Institute's Bioassays or the National Toxicology Program's 2-year carcinogenicity studies. Thirteen hepatic lesions identified from cases within the database were re-evaluated microscopically and selected for further study. These lesions were present in ten males and three females that were between 85 and 113 weeks of age at the time of death. Grossly, the liver lesions were described as white to yellow or red to brown nodules/masses or foci that ranged from 2.0 to 25 mm in diameter. The lesions commonly involved the median and left lateral hepatic lobes. Microscopically, many of the lesions closely resembled lipomas described in the liver of human beings, and they consisted of nonencapsulated mature adipose-like tissue with irregular margins. The majority of the cells that comprised the lipomatous lesions were signet-ring shaped. These cells were positive for lipid as evidenced with oil red-O. The lipid droplets were also present within the hepatocytes that comprised the hepatic plates trapped within or surrounding many of the lipomatous lesions. At the margins of many of the lesions there were spindle-shaped cells that contained small intracytoplasmic lipid vacuoles. These cells were often within a stromal matrix that had focal areas of collagen and mucopolysaccharides, as evidenced by weak staining with Masson's trichrome and periodic acid-Schiff's stains, respectively. There was also disruption of the reticulum fibers in many of the lesions, as noted with a Gomori's reticulum stain. Ultrastructurally, cytoplasmic organelles, such as rough endoplasmic reticulum, free ribosomes and small lipid vacuoles, were present in the spindle-shaped cells, whereas signet-ring-shaped cells had few discernible organelles due to peripheral compression of the cytoplasm by single large vacuoles occupying the cytoplasmic space. The spindle-shaped cells were free of lysosomes. Thin collagen fibers were seen in contact with some of the spindle-shaped cells and were located between these cells and adjacent hepatocytes, or endothelial cells lining sinusoidal capillaries. A distinct basal lamina was not associated with spindle- or signet-ring-shaped cells. Similar lipomatous lesions were not found in other visceral organs. The exact cellular origin of the hepatic lesions described here is not known.
Animals↗