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Biomedical subjects

E M Rubin

Publications and source records attributed to E M Rubin.

107 records · Page 6Linked to original sources
PubMed1991

Expression of human apolipoprotein A-I in transgenic mice results in reduced plasma levels of murine apolipoprotein A-I and the appearance of two new high density lipoprotein size subclasses.

In Western societies high density lipoprotein (HDL) levels correlate inversely with the risk for coronary heart disease. The primary protein component of both human and mouse HDL is apolipoprotein A-I (apoAI), which comprises greater than 70% of HDL protein and 30% of HDL mass. Human HDLs include particles of several distinct size subpopulations, whereas HDLs from inbred C57BL/6 mice contain a single population of particles. To study the regulation of apoAI expression and its role in HDL assembly, we created transgenic C57BL/6 mice containing the human apoAI gene. Two independent lines of transgenic mice with approximately twice the normal plasma levels of total apoAI were studied. The level of mouse apoAI is reduced greater than 4-fold in both transgenic lines, comprising only 4% of total plasma apoAI levels in one transgenic line and 13% in the other. We demonstrate that the mechanism responsible for the decrease in mouse apoAI is posttranscriptional. Parallel to the replacement of mouse with human apoAI, the single HDL species normally present in the plasma of C57BL/6 is replaced by two HDL subclasses similar in size to human HDL2b and HDL3a. The changes in murine apolipoprotein levels and HDL subclass size are inherited by all transgenic offspring of the two founder animals. These results suggest a dominant role of apoAI in determining the HDL particle size distribution and a mechanism involving expression of human apoAI transgenes that alters the plasma levels of mouse apoAI.

Animals↗
PubMed1991

Hypoxia-induced in vivo sickling of transgenic mouse red cells.

To develop an animal model for sickle cell anemia, we have created transgenic mice that express a severe naturally occurring human sickling hemoglobin, Hb S Antilles. Due to its low solubility and oxygen affinity, Hb S Antilles has a greater propensity to cause red cell sickling than Hb S. To make transgenic animals that express a high level of Hb S Antilles, the erythroid-specific DNAse I hypersensitive site II from the human beta-globin cluster was linked independently to the human alpha 2-globin gene and to the beta S Antilles gene. Embryos were injected with both constructs simultaneously and seven transgenic mice were obtained, three of which contained both the human alpha and the human beta S Antilles transgene. After crossing the human transgenes into the mouse beta-thalassemic background a transgenic mouse line was derived in which approximately half the beta-globin chains in the murine red cells were human beta S Antilles. Deoxygenation of the transgenic red cells in vitro resulted in extensive sickling. An increase of in vivo sickling was achieved by placing these transgenic mice in a low oxygen environment. This murine model for red cell sickling should help to advance our understanding of sickle cell disease and may provide a model to test therapeutic interventions.

Animals↗
PubMed1990

Developmental regulation of the human zeta globin gene in transgenic mice.

We have characterized the expression of the human zeta (zeta) gene, which encodes an embryonic alpha-like globin, in transgenic mice. We find that a 777 base pair fragment spanning erythroid specific hypersensitive site II (HSII) from the distal 5. region of the human beta globin gene cluster potentiates expression of the zeta globin gene. In the absence of the HSII fragment, no zeta expression is observed. Expression of the human zeta gene in mice parallels expression of a murine embryonic alpha-like globin gene (x). Thus, expression of the human zeta gene in mice requires linkage to an erythroid-specific enhancer sequence, but the presence of the enhancer does not affect the developmental regulation of the transgene. Our results indicate that the factors involved in switching from embryonic to adult alpha globin gene expression during development are evolutionarily conserved, and suggest that the transgenic mouse is an in vivo system in which the requirements for the developmental switch in alpha globin gene expression can be analyzed in detail.

Animals↗
PubMed1989

Effect of chest wall oscillation on mucus clearance: comparison of two vibrators.

This study was designed to investigate the effect of an experimental low-energy chest wall oscillator and of a commercial chest percussor on central airway mucociliary clearance. Five normal dogs were anesthetized, intubated, and placed supine in a trough to which the oscillator or percussor was mounted. Tracheal mucus velocity (TMV) was measured by radiopaque particle or charcoal spot movement. The commercial percussor (a fixed sinusoidal device) used at its minimum frequency of 40 Hz, produced a mean (+/- SE) maximum expiratory flow rate of 0.25 +/- 0.04 L/sec at the airway opening, and had no measurable effect on TMV. The experimental oscillator, when operated at a level sufficient to generate flows of 2-3 L/sec, and with an unbiased 13-Hz sine wave (estimated energy, 150 W), increased mean TMV to 204 +/- 13% of control (P less than 0.003); the percent increase was independent of baseline TMV. We conclude that moderate oscillatory power applied to the chest wall can enhance mucus clearance in central airways, but that currently available commercial percussors may not meet the mechanical requirements for this effect.

Animals↗
PubMed1989

Newborn screening by DNA analysis of dried blood spots.

Amplification of DNA recovered from a dried blood spot was used to genotype individuals with sickle cell disease, sickle cell carriers, and controls. A single 200-microliters blood spot applied to a filter paper provides sufficient material for more than 20 genetic analyses. In addition, the stability of the DNA is such that adequate material for amplification can be isolated from dried blood spots up to a year following collection. The DNA analysis methods described in this study could be applied to large-scale screening of newborns for genetic disorders.

Adult↗
PubMed1988

Effect of human beta (s)-globin chains on cellular properties of red cells from beta-thalassemic mice.

The transgenic mouse system provides an in vivo setting in which to examine the effects on mouse red cells of hemoglobin genes that have been genetically introduced into the animals' genome. In this report, we have analyzed the cellular properties of red cells from homozygous beta-thalassemic mice (Hbbth-1/Hbbth-1), homozygous beta-thalassemic transgenic mice containing a human beta-sickle (beta(s)) gene (Hbb(th-1)/Hbb(th-1) + beta(s)), and normal animals. The presence of human beta(s)-globin chains in red cells from the Hbbth-1/Hbb(th-1) + beta(s) transgenic animals was noted to have a significant effect on cellular deformability and density distribution, as well as on the degree of anemia in these animals. We conclude from these studies that red cell deformability and density distribution is a sensitive means for assessing at the cellular level the effects of globin genes genetically introduced into whole organisms. In addition, these studies suggest that small decreases in the amount of excess alpha-globin chains can significantly ameliorate the severity of anemia in the beta-thalassemic mouse.

Animals↗
PubMed1988

Introduction and expression of the human Bs-globin gene in transgenic mice.

Owing to the episodic and unpredictable nature of the sickling crisis, many aspects of the disease sickle cell anemia have resisted in vivo analysis. The lack of an animal model has hindered the pathophysiological investigation of this disease, as well as deterred the development of pharmacological therapies. The transgenic mouse system offers a new means for creating animals that make a specified mutant gene product, and we have used this system to create a series of mice that contain the human beta s-globin gene. These animals express this gene in the appropriate tissues and at the same point in development as the adult mouse globin genes are expressed. We have crossed the human beta s-containing transgenic mice with a beta-thalassemic mouse line and examined the hemoglobins produced by these mice. Their red cells contain 10% mouse alpha/human beta s hybrid hemoglobin, which partially corrects the thalassemic phenotype of the homozygous beta-thalassemic animals. Though the red cells do not sickle, other properties of the human beta s gene in these mice indicate the potential for the eventual development of a transgenic animal model for sickle cell anemia.

Alleles↗
PubMed1986

Unilateral pulmonary hyperinflation from mucus check-valve mechanism.

Mucus plugging of a large airway resulted in the formation of a check-valve mechanism and pulmonary hyperinflation, rather than atelectasis. Fiberoptic bronchoscopy was both diagnostic and curative. The physician should be aware that mucus plugging may have unusual presentations and may mimic other clinical entities.

Adult↗
PubMed1985

A simple sensitive prenatal test for hydrops fetalis caused by alpha-thalassaemia.

Slot blot analysis was used to differentiate between the genotypes of homozygous alpha-thalassaemia and those of haemoglobin-H disease and alpha-thalassaemia trait. The method is simple and rapid because restriction enzyme digestion and gel electrophoresis are not needed. Because of the great sensitivity of the test, as little as 0.5 micrograms of DNA can be studied with an 35S-labelled probe which has a longer isotopic half life than the 32P probes normally used for gene mapping. This assay should facilitate prenatal diagnosis in countries where pregnancies at risk for alpha-thalassaemia are common.

Amnion↗
PubMed1981

Premature termination of treatment among alcoholics: predicting outpatient clinic dropouts.

Authors predicted that adult alcoholics with relatively higher scores on obsessive-compulsive drinking subscale of Alcohol Use Inventory (AUI-4) and psychasthenia scale of Minnesota Multiphasic Personality Inventory (MMPI-7) would be better candidates for successful completion of traditional outpatient treatment. Both tests were administered to 89 successively admitted outpatients who were tracked through treatment and later classified as dropouts (premature unilateral termination of treatment, N = 57), mutuals (patient-therapist agreement on appropriate termination, N = 22), or open cases (patients still in treatment at end of 6 months, N = 10). AUI-4, but not MMPI-7, successfully identified dropouts, mutuals, and open cases, and significantly differentiated between dropouts and all other patients. AUI-4 and MMPI-7 were significantly and positively correlated, and AUI-4, but not MMPI-7, was significantly and positively related to number of therapy sessions.

Adolescent↗
PubMed1980

Expression of thymidylate synthetase activity in Bacillus subtilis upon integration of a cloned gene from Escherichia coli.

The gene from Escherichia coli encoding thymidylate synthetase was cloned in the plasmid pBR322. The resulting chimeric plasmid, pER2, was effective in transforming both E. coli and Bacillus subtilis to thymine prototrophy. Uncloned linear E. coli chromosomal DNA was unable to transform thymine-requiring strains of B. subtilis to thymine independence. Linearization of the chimeric plasmid, pER2, with restriction enzymes markedly diminished its ability to transform B. subtilis auxotrophs. The Thy+ transformants derived from the transformation of B. subtilis with pER2 DNA did not contain detectable extrachromosomal DNA as demonstrated by Southern hybridization patterns and centrifugation in CsCl gradients of DNA isolated from B. subtilis colonies transformed with the chimeric plasmid. We conclude that the DNA from the chimeric plasmid was integrated into the chromosome of B. subtilis, demonstrating that extensive homology is not required for the integration of foreign DNA. This is the first reported case of a gene from a Gram-negative bacterium functioning in a Gram-positive organism.

Bacillus subtilis↗
PubMed1979

Sickle cell trait/hereditary persistence of fetal hemoglobin trait. Misdiagnosis as sickle cell anemia by newborn screening.

A black female infant, reported as a result of mandatory newborn screening to have sickle cell anemia, was found at 8 months of age to have instead the entirely benign disorder sickle cell trait/hereditary persistence of fetal hemoglobin trait. The finding of hemoglobin S without Hb A does not suffice for the diagnosis of homozygous Hb S. Screening programs that diagnose sickle cell aneimia without first demonstrating sickle hemoglobin in both parents will consistently misdiagnose several more benign hemoglobin states as sickle cell anemia.

Anemia, Sickle Cell↗
PubMedDate not supplied

A common phenotype associated with atherogenesis in diverse mouse models of vascular lipid lesions.

The introduction of a range of different genetic modifications in mice results in altered lipoprotein metabolism and the development of vascular lipid lesions. At present, however, it is unclear to what extent the molecular events underlying lipid lesion formation are similar in these different mouse models of atherosclerosis. The aim of this study was to compare the protein expression pattern of lipid lesions from seven different mouse lines with varying susceptibility to vascular lipid lesion development, to determine to what extent lesions induced by different genetic interventions have a similar composition. The proteins we have measured, using quantitative immunofluorescence, are proteins whose expression is known to be modulated during atherogenesis in humans, including plasminogen activator inhibitor (PAI)-1, transforming growth factor (TGF)-beta 1, osteopontin and the macrophage marker CD11b. In all the mice lines we have investigated, PAI-1 was elevated wherever lesions developed. Active TGF-beta was depressed in the vessel wall of mice which developed lipid lesions, particularly in the intima. In contrast, TGF-beta 1 antigen (active plus latent TGF-beta 1) was increased at lesion sites. Accumulation of osteopontin and, with the marked exception of apolipoprotein(a) transgenic mice, tissue macrophages occurred at sites of lipid deposition in the vessel wall. Each lesion, irrespective of its size and the mouse strain in which it developed, had similar amounts of PAI-1, active TGF-beta and osteopontin per unit area of lesion. These data are consistent with a common phenotype accompanying atherogenesis, irrespective of the genetic basis of susceptibility.

Animals↗