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Biomedical subjects

J Frank

Publications and source records attributed to J Frank.

At least 235 records · Page 13Linked to original sources
PubMed1993

Three-dimensional architecture of human alpha 2-macroglobulin transformed with methylamine.

A frozen-hydrated sample embedded in vitreous ice of human alpha 2-macroglobulin transformed by methylamine was imaged by cryoelectron microscopy and reconstructed in three dimensions. In the reconstruction, the cage-like architecture of this protease inhibitor is fully revealed with a clear visualization of two lozenge-shaped lateral walls connected by thin bridges. The shape and dimensions of the internal cavity normally containing the trapped protease(s) is described. The possible locations of the thiol ester sites and inter-subunit connections are also discussed.

Image Processing, Computer-Assisted↗
PubMed1993

Reduction of background problems in nonradioactive northern and Southern blot analyses enables higher sensitivity than 32P-based hybridizations.

An improved chemiluminescence-based RNA/DNA detection procedure offering a widely applicable alternative to the conventional 32P labeling employed in molecular biology is described. Even highly sensitive applications such as Northern blot analysis of low-copy RNAs are shown to be feasible now without radioactive labeling. Improved quality of nonradioactive detection was obtained by the use of digoxigenin-labeled nucleotides in combination with dioxetane substrates which are decomposed by the hydrolysis of alkaline phosphatase. Previously existing problems involving unacceptably high background signals in nonradioactive labeling procedures were eliminated by the application of a modified RNA/DNA transfer, hybridization, and detection protocol. The data presented here delineate a system consistently superior to radioactivity and should considerably increase the usefulness of nonradioactively labeled probes detected by chemiluminescence.

Alkaline Phosphatase↗
PubMed1993

Quaternary structure of quinoprotein ethanol dehydrogenase from Pseudomonas aeruginosa and its reoxidation with a novel cytochrome c from this organism.

Quinoprotein (2,7,9-tricarboxy-1H-pyrrolo-[2,3-f]quinoline-4,5-dione quinone form (PQQ)-containing) ethanol dehydrogenase (EDH) from Pseudomonas aeruginosa ATCC 17933 was purified to homogeneity. EDH has an alpha 2 beta 2 configuration and subunits comparable in size to those of methanol dehydrogenase (MDH). Compared with other PQQ-containing dehydrogenases, Ca2+ is rather loosely bound and it seems necessary for PQQ binding and stability of EDH. Two soluble cytochromes c were detected in extracts from ethanol-grown cells and both were purified. One of these has an alpha-band at 551 nm for its reduced form, the oxidized form being an excellent electron acceptor for the semiquinone form of EDH. Since this cytochrome is quite different from the already known cytochrome c551 (operating in nitrate respiration) of this organism, it is indicated here as cytochrome cEDH. Comparison of the N-terminal amino acid sequence of cytochrome cEDH with the complete sequence of cytochrome cL (the electron acceptor of MDH), cytochrome cH (the electron acceptor of cytochrome cL) and cytochrome c551 revealed some similarity only to internal stretches of amino acids of the last two. The other soluble cytochrome appeared to be the already-known cytochrome c556. Since it was not an electron acceptor for cytochrome cEDH (neither for EDH), cytochrome cH is lacking in the quinoprotein-EDH-ethanol oxidation system of P. aeruginosa. It seems, therefore, that the respiratory chains for MDH and EDH are different.

Alcohol Oxidoreductases↗
PubMed1993

Modelling psychosocial effects of exposure to solid waste facilities.

A parallel case study design was used to investigate psychosocial effects in populations exposed to solid waste facilities. Psychosocial effects were defined as a complex of distress, dysfunction and disability, manifested in a range of psychological, social and behavioural outcomes, as a consequence of actual or perceived environmental contamination. This paper presents the results of logistic regression analyses designed to identify determinants of psychosocial effects of exposure. The data come from an epidemiologic survey of residents (N = 696) living within a prescribed radius from each of three solid waste facilities in southern Ontario. The analytical model has three main components: external variables (e.g. individual and exposure-related variables); mediating variables (e.g. social network membership and involvement, general health status measures); and outcome variables (e.g. concern, effects and actions). Results for a series of site specific analyses show that outcome measures can be successfully explained by a combination of external and mediating factors. In general, variables from each of the three main components enter the concern-related models while the action models are clearly dominated by social network variables. Analyses using data from all three sites indicate the explanatory power of site-related characteristics. However, given the number and diversity of variables in the models, there is no support for a simple cause and effect relationship. The implication is that strategies aimed to address and alleviate psychosocial effects need to be specific to the characteristics of the populations in particular settings.

Adaptation, Psychological↗
PubMed1993

Flopping polypeptide chains and Suleika's subtle imperfections: analysis of variations in the electron micrograph of a purple membrane crystal.

Patch averaging, a method of data analysis combining correlation averaging with multivariate statistical analysis, was applied to a high-resolution image of a purple membrane thin crystal. The observed variational patterns fall in two categories: non-crystallographic, related to small electron-optical distortions of the microscope, and crystallographic, conceivably related to variations in the locations of flexible segments of the polypeptide chain on the surface of the membrane.

Bacteriorhodopsins↗
PubMed1993

Structure of the colcemid-treated PtK1 kinetochore outer plate as determined by high voltage electron microscopic tomography.

High voltage electron microscopic tomography was used to determine the organization of the kinetochore plate and its attachment to the underlying chromosome. Six reconstructions were computed from thick sections of Colcemid-treated PtK1 cells and analyzed by a number of computer graphics methods including extensive thin slicing, three-dimensional masking, and volume rendering. When viewed en-face the kinetochore plate appeared to be constructed from a scaffold of numerous 10-20-nm thick fibers or rods. Although the fibers exhibited regions of parallel alignment and hints of a lattice, they were highly variable in length, orientation and spacing. When viewed in stereo, groups of these fibers were often seen oriented in different directions at different depths to give an overall matted appearance to the structure. When viewed "on edge," the plate was 35-40 nm thick, and in thin slices many regions were tripartite with electron-opaque domains, separated by a more translucent middle layer, forming the inner and outer plate boundaries. These domains were joined at irregular intervals. In some slices, each domain appeared as a linear array of 10-20-nm dots or rods embedded in a less electron-opaque matrix, and adjacent dots within or between domains often appeared fused to form larger blocks. The plate was connected to the underlying chromosome by less densely arrayed 10-20-nm thick fibers that contacted the chromosome-facing (i.e., inner) surface of the plate in numerous patches. These patches tended to be arrayed in parallel rows perpendicular to the long axis of the chromosome. In contrast to connecting fibers, corona fibers were more uniformly distributed over the cytoplasmic-facing (i.e., outer) surface of the plate. When large portions of the reconstructions were viewed, either en-face or in successive slices parallel to the long axis of the chromosome, the edges of the plate appeared splayed into multiple "fingers" that partly encircled the primary constriction. Together these observations reveal that regions of the kinetochore outer plate contain separate structural domains, which we hypothesize to serve separate functional roles. Our three-dimensional images of the kinetochore are largely consistent with the hypothesis that the outer plate is composed of multiple identical subunits (Zinkowski, R. P., J. Meyne, and B. R. Brinkley. 1991. J. Cell Biol. 113:1091-1110).

Animals↗
PubMed1993

A prospective, randomized study of continuous versus intermittent nebulized albuterol for severe status asthmaticus in children.

OBJECTIVES: a) to determine if continuous nebulization of albuterol is more effective than intermittent nebulization in the treatment of children with status asthmaticus and impending respiratory failure; b) to determine the effect of continuous nebulization and intermittent nebulization on duration of hospital stay and bedside respiratory therapy care. DESIGN: Prospective, randomized study. SETTING: A pediatric intensive care unit (ICU) in a university children's hospital. PATIENTS: Seventeen pediatric asthmatic patients with severe status asthmaticus, with impending respiratory failure (Woods asthma score > or = 5), and without evidence of cardiac or other preexisting lung disease were admitted to the pediatric ICU. The patients were randomized to receive continuous nebulization (n = 9) or intermittent nebulization (n = 8) of albuterol. INTERVENTIONS: The asthmatic patients were randomized into two groups. The continuous group received 0.3 mg/kg/hr of albuterol by continuous nebulization; the intermittent group received 0.3 mg/kg of albuterol over 20 mins every hour. All patients received aerosol therapy through the same delivery system. MEASUREMENTS: Responses to therapy were evaluated by following asthma score, arterial blood gas values, hemodynamics, FIO2, and arterial oxygen saturation initially and at 30 mins, 1 hr, 2 hrs, 4 hrs, then every 4 hrs for a 24-hr time period. Patients were determined to no longer be in impending respiratory failure when their asthma score was < 5 for four consecutive hours. Electrocardiograms, serum electrolyte values, and creatine phosphokinase total and MB fraction values were obtained before and after treatment. Hospital stay and respiratory therapy time, in relative value units (one relative value unit = 10 mins) were analyzed from data collected from therapist bedside flow sheets. RESULTS: The patient characteristics (demographics, hemodynamics, arterial blood gas values, asthma severity, corticosteroid use, theophylline, and beta 2-adrenergic receptor agonist administration) before entry into the study did not differ between groups. Patients in the continuous group improved more rapidly and were out of impending respiratory failure sooner than patients in the intermittent group (continuous group = 12 (median) hrs (range 4 to 24) vs. intermittent group = 18 (median) hrs (range 12 to 24; p = .03). Bedside respiratory therapy time evaluated by relative value units was less for patients who received continuous nebulization of albuterol (continuous group = 14 (median) relative value units (range 6 to 26) vs. intermittent group = 33 (median) relative value units (range 25 to 49; p = .001). Hospital stay was shorter for patients who received continuous nebulization of albuterol (continuous group = 80 [median] hrs [range 51 to 173] vs. intermittent group = 147 [median] hrs [range 95 to 256]; p = .043). Hemodynamics, serum potassium, and creatine phosphokinase concentrations did not differ before and after the study in either group. CONCLUSIONS: In children with impending respiratory failure due to status asthmaticus, continuous nebulization of albuterol is safe and results in more rapid clinical improvement than intermittent nebulization. Respiratory therapy required at the bedside and duration of hospital stay were substantially less for patients receiving continuous nebulization of albuterol, which suggests that continuous nebulization of albuterol is more cost effective than intermittent nebulization.

Adolescent↗
PubMed1993

Role of professional nurses in the field of developmental disabilities.

The definition and clarification of the role of professional nurses on the interdisciplinary team was the focus of this paper. Professional services that other team members, administrators, individuals with developmental disabilities, and their families may expect from registered nurses were outlined. The AAMR Nursing Division Position Statement was presented in order to inform the public and provide a framework of practice for professional nurse specialists in the field of developmental disabilities.

Education of Persons with Intellectual Disabilitie↗
PubMed1992

[Monotherapy with the ACE-inhibitor ramipril or the calcium antagonist nitrendipine in essential hypertension].

Angiotensin-converting enzyme (ACE) inhibitors and calcium antagonists have, by reason of their potentially favourable pharmacological profile, become increasingly established in the treatment of hypertension in recent years. In a double-blind randomized study with an initial placebo phase, carried out by practising physicians and thus aimed at the "usual" practice patients with essential hypertension, we assessed (1) the antihypertensive effect and tolerability of an ACE inhibitor (ramipril, 5 mg/d) or a calcium antagonist (nitrendipine, 20 mg/d) given in a single daily dose, and (2) a possible age-dependent blood pressure (BP) effect of these therapies. In the 4 weeks' placebo phase, the two treatment groups were comparable as regards average age (49.6 and 49.4 years), age-range (27-67 and 25-64 years) and BP. Fifty-two patients completed the following 6 weeks' phase with active drug therapy. On ramipril (n = 26), the BP measured 24-25 hours after the last drug administration was reduced in the supine position from an average of 155/102 to 142/91 mmHg (mean reduction -10.1%) and in the upright position from 156/106 to 141/96 mmHg (-9.3%). Nitrendipine (n = 26) reduced the average BP from 155/102 to 147/94 mmHg (-6.8%) and from 155/106 to 146/99 mmHg (-6.6%) respectively. BP-lowering effects of both treatments were largely independent of age. Including the patients who discontinued the study prematurely because of side effects (1 on ramipril, 4 on nitrendipine), the "intention to treat analysis" shows BP normalization rates (diastolic < or = 90 mm Hg) of 55% (ramipril) and 30% (nitrendipine) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Purification and partial characterization of a thermostable trithionate hydrolase from the acidophilic sulphur oxidizer Thiobacillus acidophilus.

Cell-free extracts of Thiobacillus acidophilus catalysed the quantitative conversion of trithionate (S3O6(2-) to thiosulphate and sulphate. A continuous assay for quantification of experimental results was based on the difference in absorbance between trithionate and thiosulphate at 220 nm. Trithionate hydrolase was purified to near homogeneity from cell-free extracts of T. acidophilus. The molecular masses of the native enzyme and the subunit were 99 kDa (gel filtration) and 34 kDa (SDS/PAGE). The purified enzyme has a pH optimum of 3.5-4.5 and a temperature optimum of 70 degrees C. Enzyme activity was stimulated by sulphate. The stimulation of the enzyme activity by sulphate was half maximal at a concentration of 0.23 M. The Km for trithionate is 70 microM at 30 degrees C and 270 microM at 70 degrees C. Enzyme activity was lost after 36 days at 0 degrees C, 27 days at 70 degrees C; but after 97 days at 30 degrees C, 40% of the initial activity was still present: The enzyme activity was inhibited by mercury chloride, N-ethylmaleimide, thiosulphate and tetrathionate. Tetrathionate S4O6(2-) was not hydrolysed by trithionate hydrolase.

Ammonium Sulfate↗
PubMed1992

Eukaryotic initiation factor 3 does not prevent association through physical blockage of the ribosomal subunit-subunit interface.

The "native" 40 S ribosomal subunit, in which the protein eukaryotic initiation factor 3 is bound to the 40 S small ribosomal subunit, has been reconstructed to 48 A resolution. Comparison with a previous three-dimensional reconstruction of the "derived" 40 S subunit lacking any non-ribosomal components reveals the attachment site and morphology of the factor. It is a large (approximately 165 to 170 A long), bilobed, elongate structure, attached to the back lobes of the 40 S subunit by two strand-like features. Significantly, the factor is oriented away from the 60 S-subunit-40 S-subunit interface surface of the 40 S particle, suggesting that its anti-association activity is not accomplished via simple physical blockage of that surface.

Animals↗
PubMed1992

The archaebacterial hypusine-containing protein. Structural features suggest common ancestry with eukaryotic translation initiation factor 5A.

The amino acid hypusine is formed by post-translational modification of a lysine residue in eukaryotes and archaebacteria but up to now only the eukaryotic translation initiation factor eIF-5A has been known to contain this unique component. We isolated and purified a hypusine-containing protein from the thermophilic archaebacterium Sulfolobus acidocaldarius. The mainly cytosolic protein comprised about 0.03% of the post-ribosomal supernatant protein. No other hypusine-containing protein could be detected in S. acidocaldarius. The molar ratio of hypusine/hypusine-containing protein was 1:1. SDS/PAGE showed a molecular mass of 16.8 kDa; a pI of 7.8 for the native protein resulted from IEF. The N-terminus was blocked. Four cyanogen bromide fragments were partially sequenced and used to derive two 17-base oligonucleotide probes. A 3-kb HindIII fragment of genomic DNA hybridizing with both probes was cloned. By sequencing of exonuclease III deletion clones an open reading frame of 405 nucleotides was found coding for a protein of 135 amino acids with a molecular mass of 15 kDa. It contained all cyanogen bromide sequences analysed. Sequence alignment revealed that seven of eight residues around Lys40 in the Sulfolobus hypusine-containing protein were identical to the nonapeptides centered by hypusine in the three eIF-5A proteins sequenced so far. The Edman procedure gave no phenylthiohydantoin derivative for this position. For a central region of 44 residues a sequence similarity of 54% between the archaebacterial and eukaryotic proteins was calculated; for the total sequence about 33% similarity resulted. In addition, there were a number of conservative changes. The unique lysine modification surrounded by a conserved sequence strongly suggests a common ancestry of archaebacterial hypusine-containing protein and eIF-5A. Together with similarities in molecular mass and intracellular localization, it may point to an analogous biochemical function.

Amino Acid Sequence↗
PubMed1992

Three-dimensional reconstruction of single particles negatively stained or in vitreous ice.

The random-conical reconstruction method has been highly successful in three-dimensional imaging of macromolecules under low-dose conditions. This article summarizes the different steps of this technique as applied to molecules prepared with negative staining or vitreous ice, and sketches out the current directions of development. We anticipate that by using new instrumental developments, transfer function correction and computational refinement techniques, a resolution in the range of 7-10 A could ultimately be achieved.

Calcium Channels↗
PubMed1992

Do coronary heart disease risk factors measured in the elderly have the same predictive roles as in the middle aged. Comparisons of relative and attributable risks.

Risk factors for the 12-year incidence of definite coronary heart disease (CHD) among 3440 men who were middle-aged (51 to 59 years old) and 1419 men who were elderly (65 to 74 years old) at baseline examination were examined for differences in predictive values in terms of both relative risk and attributable (excess) risk of the highest versus the lowest quartile or appropriate categories. In multivariate models using Cox life-table regression procedures, serum cholesterol level, cigarette smoking, systolic blood pressure, and history of treatment for diabetes were significant predictors of incident CHD for both age groups. Alcohol consumption when modeled as drinker versus nondrinker showed a protective effect in both younger and older men. There was no dose relationship, however, among elderly drinkers. While the relative risks for the variables studied were similar between the two age groups, the excess risk was typically between 1.5 to 2.0 times higher for the older than the middle-aged men. In contrast, the detrimental effect of adiposity as measured by body mass index appeared to decline after age 65 for both measures of risk. This may partly be attributed to diminished adiposity overall in the older age group. The implications of these results are that serum cholesterol level, smoking, hypertension, diabetes, and possibly alcohol consumption continue to be important predictors for CHD when measured after age 65, and that the public health impact of these risk factors, in terms of excess risk, may be more important in the elderly.

Age Factors↗
PubMed1992

Measurement of neuronal surface area using high-voltage electron microscope tomography.

High-voltage electron microscopy (HVEM) and axial tomography were used to reconstruct the three-dimensional structure of dendrites of intracellularly stained neostriatal spiny neurons. Neurons were stained using iontophoretic injection of horseradish peroxidase from an intracellular micropipet. Thick sections were cut on a vibratome, reacted with diaminobenzidine, and embedded in plastic. High-voltage electron microscopy was used to obtain high-resolution images of neuronal processes in 2- to 3-micron plastic sections cut from those blocks. Series of high-voltage electron micrographs were taken at 2 degrees increments of specimen tilt over a range of at least +/- 60 degrees, and three-dimensional reconstructions were generated from the series using an R-weighted backprojection method. An interactive procedure was used to draw the dendritic profiles from slices through the reconstructed volume and to measure volumes and surface areas of the dendrites. Values obtained in this manner matched previous findings using reconstruction from serial thin sections. The HVEM-tomography method offers an alternative to the serial-thin-section method for the quantitative analysis of neuronal shape.

Animals↗
PubMed1992

Cryo-EM of the native structure of the calcium release channel/ryanodine receptor from sarcoplasmic reticulum.

The native structure of the calcium release channel (ryanodine receptor) from rabbit skeletal muscle has been analyzed in two dimensions from electron micrographs of frozen hydrated specimens. Within a resolution of 3.0 nm there is excellent agreement between the structure as seen in vitreous water and in negative stained specimens. Features seen in the three-dimensional reconstruction of the negatively stained channel can be identified in the projection of the unstained receptor.

Animals↗