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Biomedical subjects

H Taylor

Publications and source records attributed to H Taylor.

At least 19 recordsLinked to original sources
PubMed1992

The uninsured and the debate over the repeal of the Massachusetts universal health care law.

OBJECTIVES: The debate in Massachusetts over the repeal of the first state-based "pay or play" universal health plan is discussed using data from a survey of 1066 Massachusetts households. The survey attempted to measure the problems of the uninsured, to estimate the likelihood that they would buy insurance if offered, and to calculate the proportion of the uninsured who would be covered under an employer mandate. DESIGN: A survey conducted in person and by telephone in 1066 households, with an oversample of uninsured households, using stratification, clustering, disproportionate sampling, and poststatistical weighting. PARTICIPANTS: Adults aged 18 years and older who were knowledgeable about the insurance status of persons in their household. MAIN OUTCOME MEASURES: Insurance status, employment status, access to and use of health services, and willingness to purchase health insurance. RESULTS: First, the present system of hospital-based uncompensated care in Massachusetts is inadequate by itself to meet the needs of uninsured residents. Uninsured persons are less likely than insured ones to seek medical care for chronic health problems and serious symptoms requiring evaluation. Second, 83% of uninsured families and 24% of uninsured individual respondents would purchase one of several insurance options with 30% of the cost subsidized. Last, the employer mandate provisions of the legislation would cover 43% of the uninsured in Massachusetts. CONCLUSION: In the current economic climate, the political viability of the universal health care plan and similar national initiatives is uncertain given the intractable conflict between perceptions of the financial stability of small businesses that do not offer insurance and the health care needs of uninsured individuals.

Cluster Analysis↗
PubMed1992

Cloning and structural analysis of the human c-kit gene.

The recent identification of the mouse White spotting and Steel loci as genes encoding the c-kit receptor and its ligand, respectively, has shed light on the importance of this ligand and receptor in embryogenesis, melanogenesis and hematopoiesis. In order to determine if the c-kit proto-oncogene is involved in human disease, we isolated seven overlapping lambda recombinants, using a fetal brain cDNA, and characterized the normal human gene (KIT). The longest mapped transcript is 5230 bp, is alternatively spliced and includes 21 exons that span more than 70 kb of DNA. From the exon-intron structure, we have localized an alternative splice site to the 3' end of exon 9. The overall c-kit gene structure closely resembles that found in the CSF-1R gene (c-fms). This similarity includes a large first intron, the same number of exons containing translated sequence and very similar exon-intron boundaries. Using pulsed-field gel electrophoresis, we have linked KIT to the platelet-derived growth factor receptor A gene, with both residing on a 700-kb BssHI fragment. These data will allow investigation into the control of KIT expression and the potential to identify mutations or altered expression of this gene in human disease.

Base Sequence↗
PubMed1992

Indirect effect of guanine nucleotides on antagonist binding to A1 adenosine receptors: occupation of cryptic binding sites by endogenous vesicular adenosine.

Guanine nucleotides such as guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) have been found to increase the binding of antagonists to adenosine A1 receptors. This response can be attributed either to a direct effect of GTP on receptors to increase antagonist affinity or to an indirect effect to decrease the affinity of receptors for a pool of endogenous adenosine that cannot be readily removed from membranes. In this study, adenosine content was measured in preparations of membranes and 3-[(3-cholamidopropyl)dimethylamino]-1-propanesulfonate (CHAPS)-solubilized receptors by a sensitive radioimmunoassay. In both preparations, pools of adenosine (2.5-10 pmol/mg of protein) were detected that were resistant to deamination by added adenosine deaminase (0.5-3 units/ml) unless membrane lipids were first dissolved in acetone. Electron microscopic examination of crude CHAPS-solubilized receptors revealed the existence of small vesicles (< 1 microns in diameter). Furthermore, most "solubilized" receptors were retained by a 0.1-microns filter. The effects of GTP gamma S were evaluated on the binding of an antagonist, 3-(4-amino-3-125I-phenethyl)-1-propyl-8-cyclopentylxanthine (125I-BW-A844U), to A1 receptors of bovine brain membranes, receptors solubilized in CHAPS (crude solubilized), or receptors partially co-purified with G proteins by agonist affinity chromatography (partially purified). GTP gamma S (10 microM) increased antagonist binding to membranes (20-50%) and crude CHAPS-solubilized receptors (> 200%) but increased binding to partially purified receptors by only 10-15%. GTP gamma S decreased agonist (125I-N6-aminobenzyladenosine) binding and increased antagonist Bmax, but did not significantly decrease (5%) the dissociation rate of the antagonist. Omission of Mg2+ mimicked the effects of GTP gamma S on agonist and antagonist binding and increased both the association and dissociation rates of 125I-BW-A844U. These data suggest that a Mg(2+)-dependent GTP gamma S-induced increase in antagonist binding to membranes and solubilized receptors is primarily due to unmasking of cryptic binding sites occupied by contaminating vesicular adenosine. These findings are consistent with the observation that adenosine receptor antagonists have been found to have little or no inverse agonist physiological effects in well oxygenated tissues.

Adenosine↗
PubMed1991

Discrete subpopulations, defined by CD45 isoforms, coexist within the leukaemic cells of B-chronic lymphocytic leukaemia patients.

The expression of CD45 isoforms by B-CLL leukaemic lymphocytes has been analysed by 2 colour flow cytometry and vectorial iodination. The cytometry has demonstrated the presence of cells with different CD45 phenotypes which vary in the relative expression of the CD45RA and CD45RO determinants. Discrete populations have been detected which can coexist within an individual patient. One of these populations which is CD45RO-negative consists of cells expressing only the 230 kD isoform, in the others the smaller isoforms are expressed, the appearance of the CD45RO determinant of 180 kD being accompanied by the appearance of the 190 kD isoform. The relative proportion of cell populations is stable within patients but can be altered by phorbol ester which enhances CD45RO expression and diminishes CD45RA expression. The populations may be partially resolved by the density gradient fractionation.

Antigens, CD↗
PubMed1991

Hemoglobin Columbia Missouri or alpha 2[88 (F9) Ala----Val]beta 2: a new high-oxygen-affinity hemoglobin that causes erythrocytosis.

A previously undescribed hemoglobin variant, hemoglobin Columbia Missouri, alpha 88 (F9) Ala----Val, was detected in a 22-year-old white man who was undergoing assessment for erythrocytosis. This new hemoglobin variant does not separate from hemoglobin A by electrophoresis in conventional media, by isoelectric focusing, or by electrophoresis of purified globin chains in 8 M urea. It exhibits a high oxygen affinity, with a P50 (oxygen tension at 50% saturation) of 19.3 torr for the patient's whole blood. The substitution of hemoglobin Columbia Missouri is an internal residue near the end of the F helix of the alpha chain. Hemoglobin Okazaki has an arginyl residue substitution for a cysteinyl residue at F9 (beta 93) in the beta chain. In comparison with hemoglobin Okazaki, the substitution in hemoglobin Columbia Missouri has a more pronounced effect on oxygen affinity. Consequently, hemoglobin Columbia Missouri is associated with erythrocytosis, whereas hemoglobin Okazaki is not.

Adolescent↗
PubMed1991

Automated image-based cytometry with fluorescence-stained specimens.

The combination of digitized microscopy, algorithms for object recognition and fluorescent labeling is a promising approach for reliable, quick, automated and cost-effective screening of clinical specimens. We describe two conceptually different algorithms for detecting objects in fluorescence microscopic images. One, which is partially automated, compares a mask that represents a typical object with every position in the image; the other, which is fully automated, calculates threshold intensities to segment the image into regions of objects and background. Applications of the algorithms in conjunction with a prototype image-based cytometer are demonstrated for determining the DNA ploidy distribution of cultured human endometrial cells and determining the DNA ploidy distribution and the fraction of cells expressing the E6 antigen of human papilloma virus serotypes 16 and 18 in a PAP smear. The encouraging results from this study suggest that automated image-based cytometry utilizing fluorescent stains will be a valuable asset for clinical screening.

Algorithms↗
PubMed1991

Effects of acute aspartame and acute alcohol ingestion upon the cognitive performance of pilots.

Anecdotal evidence has associated the artificial sweetener aspartame with a number of symptoms of central nervous system (CNS) dysfunction. There are, however, little scientific data concerning the effect of aspartame upon complex mental operations such as those necessary for flying an aircraft. Thirteen pilots were tested in a double-blind study using the SPARTANS cognitive test battery of aviation-relevant information-processing tasks. These tasks relate to perceptual-motor abilities, spatial abilities, working memory, attentional performance, risk taking, processing flexibility, planning and sequencing ability. Subjects were tested over five sessions consisting of pretest and posttest controls and three randomly ordered treatment sessions. The treatment conditions involved an aspartame dose of 50 mg/kg body weight, a placebo condition, and an ethyl alcohol (0.1% BAL) condition as the positive control. No detectable performance decrements were associated with the aspartame condition, although decrements in psychomotor and spatial abilities were detected in the ethanol condition. Results were found to be consistent with prior flight-simulator studies of alcohol, but do not appear to support the concerns expressed in anecdotal testimony regarding the deleterious effects of aspartame upon cognitive performance.

Aerospace Medicine↗
PubMed1991

EMF primer.

Explore the source record for details and available documents.

Adult↗
PubMed1990

Electron nuclear double resonance (ENDOR) of the Qc.- ubisemiquinone radical in the mitochondrial electron transport chain.

We present an electron nuclear double resonance (ENDOR) study of the bound Qc.- ubisemiquinone in the mitochondrial quinol cytochrome c reductase complex. An ENDOR probe specifically modified for insertion into our electron paramagnetic resonance cavity was used for this study. We observed strongly hyperfine-coupled protons whose exchangeable nature indicated they were hydrogen-bonded to the quinone oxygen(s). It is thought that such hydrogen bonds are critical in binding the ubiquinone to protein, in stabilizing its semiquinone form, and in modulating the thermodynamic properties of the bound ubiquinone in the mitochondrial quinol cytochrome c reductase complex. Additional ENDOR features were assigned to protons of the quinone ring itself and to weakly coupled protons that may be associated with nearby amino acids. From very weakly hyperfine-coupled, distant, exchangeable protons there was also ENDOR evidence to suggest proximity and accessibility of the ubiquinone site to the solvent.

Animals↗
PubMed1990

Elevated human chorionic gonadotrophin levels in a patient with pancreatic carcinoma presenting with a testicular metastasis.

Elevated levels of human chorionic gonadotrophin are associated with primary testicular tumours and usually indicate the presence of trophoblastic elements. Human chorionic gonadotrophin can also be secreted by extragonadal tumours which may metastasize to the testes. A patient is described presenting with a testicular tumour secreting human chorionic gonadotrophin which later proved to be a metastasis from a pancreatic adenocarcinoma. Up to 70% of malignant pancreatic tumours can secrete human chorionic gonadotrophin.

Adenocarcinoma↗