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Biomedical subjects

J Frank

Publications and source records attributed to J Frank.

At least 325 records · Page 18Linked to original sources
PubMed1986

Modelling the incidence of childhood diarrhea.

Diarrheal disease is a primary cause of childhood mortality and morbidity in developing countries. Significant reduction depends on the identification of high-risk households which can be targetted for proven-effective interventions, such as oral rehydration therapy. This paper describes the development of a household risk assessment model in the context of an on-going diarrheal disease control in Grenada. Contingency and logit analyses of household survey data are used to identify easily observed markers of high-risk households. A three-variable logit model gives accurate predictions of self-reported diarrhea, showing that the approach can be used to develop an effective and efficient risk assessment tool.

Child↗
PubMed1986

Tomographic three-dimensional reconstruction of cilia ultrastructure from thick sections.

We have applied a computer-based tomographic technique to reconstruct the three-dimensional ultrastructure of newt lung cilia. Epon-embedded samples were cut into 0.25-micron-thick sections that were imaged at 1 MV with a high-voltage electron microscope. For the reconstruction shown, a tilt series of 53 micrographs was taken at tilt angles between -54 degrees and +50 degrees. The reconstruction was accomplished from these projections using a weighted back-projection algorithm. The 12-nm resolution of the reconstruction was sufficient to resolve the outer doublet and central pair microtubules, dynein arms, radial spokes, and central sheath structures. The reconstruction can be viewed from various angles and with appropriate parts cut away to reveal structural features of interest. The sense of depth in these views can be enhanced by stereo viewing of shaded surface images. From this reconstruction, we determined that newt lung cilia contain the more common triplet grouping of radial spokes.

Animals↗
PubMed1986

Reconstitution of molecule images analysed by correspondence analysis: a tool for structural interpretation.

Correspondence analysis is gaining increasing importance in the analysis of electron micrographs of macromolecules. Partial or complete reconstitution of images from their factorial representations is introduced as a useful tool in interpreting variational patterns and tracing their physical origin. The value of image reconstitution is demonstrated with two examples, one using a set of model images and the other a set of images of a haemocyanin molecule assembly product.

Animals↗
PubMed1986

Influence of age and sex on anal sphincters: manometric evaluation of anorectal continence.

To investigate the exact nature of anorectal continence, a manometric evaluation was performed in 88 healthy test persons with a two-balloon catheter. The pressure in the anal canal (PAC) and the rectal ampulla at rest (PAR), the maximum squeeze pressure (PAC max) and pressure rise in the anal canal after dilatation of the rectal ampulla delta PAC) were evaluated separately for men and women, and the test persons were divided into 3 age groups (group I: under 40 years, group II: 40-60 years, group III: over 60 years). PAC showed a statistically significant difference between men and women and a constant decrease with age--statistically significant for men and for women between groups II and III--whereas the statistical significance of the 3 other values had to be restricted to a constant decrease with advance in years. Anorectal continence is characterized by a PAC at rest of over 40 mm Hg, a PAC max reaching at least 80 mm Hg, a pressure gradient between rectal ampulla and anal canal of over 20 mm Hg and a delta PAC of more than 10 mm Hg. These values as well as the differences depending on age and sex should be kept in mind for the evaluation of the continence function.

Adolescent↗
PubMed1986

MRI of indeterminate adrenal masses.

The histologic type of adrenal tumors can be accurately predicted by MRI on the basis of their signal intensity on a T2-weighted image. However, a small but significant number of nonfunctioning adenomas, carcinomas, and metastases cannot be differentiated because they have similar signal intensities on a spin-echo 2500/80 scan. Eight (21%) of 38 of these tumors fell into this group. Differentiation between incidental adenomas and metastases can be conclusively achieved only when the primary neoplasm can also be imaged and displays high signal intensity on T2-weighted images.

Adenoma↗
PubMed1986

Effect of ejaculation frequency on sperm quality.

Sixty-four normozoospermic and 19 oligozoospermic males underwent sperm analyses of two successive specimens obtained at 1-, 2-, and 3-day intervals. The first specimen was produced after 3 days of abstinence. Sperm volume of normozoospermic males declined from 2.3 +/- 1.0 to 1.6 +/- 1.0 ml, 2.6 +/- 1.0 to 2.0 +/- 0.9 ml, and 2.1 +/- 0.9 to 1.9 +/- 1.0 ml at 1-, 2-, and 3-day intervals, respectively. Similarly, oligozoospermic males showed declines from 2.3 +/- 1.2 to 1.7 +/- 1.5 and 2.3 +/- 1.1 to 1.8 +/- 1.2 and an increase from 1.2 +/- 1.2 to 1.5 +/- 0.7 ml, respectively. Sperm counts of normozoospermic males declined from 65 +/- 54 to 55 +/- 34, 83 +/- 57 to 69 +/- 47, and 97 +/- 51 to 81 +/- 46 million spermatozoa/ml at 1-, 2-, and 3-day intervals, respectively. Oligozoospermic males showed declines from 5.1 +/- 5.4 to 3.8 +/- 4.1 and 8.2 +/- 8.6 to 7.2 +/- 5.2 and an increase from 3.8 +/- 0.6 to 5.7 +/- 2.1 million spermatozoal/ml at 1-, 2-, and 3-day intervals, respectively. Sperm motility of normozoospermic males varied from 41 +/- 20 to 38 +/- 18, 55 +/- 14 to 56 1/3 pm 14, and 52 +/- 15 to 52 +/- 20% at 1-, 2-, and 3-day intervals, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Ejaculation↗
PubMed1985

Isolation and characterization of a blue copper protein from Thiobacillus versutus.

The blue copper protein induced during growth of Thiobacillus versutus on methylamine was purified and characterized. It is an acidic protein (isoelectric point 4.7), contains one Cu2+ ion/enzyme molecule, is a monomeric protein (molecular mass about 14 kDa), has a maximum in its absorption spectrum at 596 nm (molar absorption coefficient 3.9 X 10(3) M-1 cm-1), shows an axial type-I electron paramagnetic resonance spectrum (g parallel = 2.239, g perpendicular = 2.046 and A parallel = 5.6 mT) and has a redox potential (Eo) of + 260 mV. In view of these properties and in view of the fact that the protein is active as an electron carrier between methylamine dehydrogenase and cytochrome c, it is concluded that it is similar to the amicyanins isolated from Methylomonas sp. strain J and Pseudomonas sp. strain AM 1.

Amino Acids↗
PubMed1985

Approach to the direct intramolecular localization of antigenic determinants in Androctonus australis hemocyanin with monoclonal antibodies by molecular immunoelectron microscopy.

Monoclonal antibodies (mAb) directed vs. subunits from hemocyanin (Hc) of the scorpion Androctonus australis were used in molecular immunoelectron microscopy (MIEM) to directly localize the epitopes within the subunits. Four types of mAb were used. First, mAb 6302, an IgG clone highly specific for subunit Aa 2, produced with native hemocyanin long strings composed of hemocyanin molecules in the side view and in the 45 degrees view. At lower concentration, "parachute" and "butterfly" structures composed of two Hc molecules and one monoclonal immunoglobin G (IgG) molecule were obtained. Fab fragments prepared from mAb 6302 bound exactly on the top and bottom edges of the molecule. The second type of mAb (6003), directed vs. subunit Aa 2, produced nice immunocomplexes with the free subunit but nothing with the native oligomer. It is suggested that due to steric hindrance or to conformational changes the epitope is not accessible in the native molecule. The third mAb belonged to the IgM class and apparently bound Hc in the Aa 2 area. However, because of the difficulty of separating the immunocomplexes from the residual mAb and the polymorphism of the IgM molecules, monoclonal IgM are no longer used for MIEM. The last type of mAb (5701) had a high affinity and a high specificity for subunit Aa 6. It produced two types of immunocomplexes with native Hc. The two types differed by a 180 degrees rotation around one of the Fab arms. These complexes, which support recent results of Wrigley et al. [Wrigley, N. G., Brown, E. B., & Skehel, J. J. (1983) J. Mol. Biol. 169, 771-774] and of Roux [Roux, K. H. (1983) Eur. J. Immunol. 14, 459-464], indicate that monoclonal IgG have a high degree of rotational flexibility around the Fab arm. Monoclonal antibody 5701 bound exactly at the corner of the molecule in the area where subunit Aa 6 is known to be located. The MIEM approach of the location of the epitope requires the model of the architecture and of the quaternary structure to be very precise. Thus, recent findings of Gaykema et al. [Gaykema, W. P. J., Hol, J. M., Vereijken, J. M., Soeter, N. M., Bak, H. J., & Beintema, J. J. (1984) Nature (London) 309, 23-29] and of Van Heel et al. [Van Heel, M., Keegstra, W., Schutter, W., & Van Bruggen, E. F. J. (1983) Life Chem. Rep., Suppl. Ser. 1, 69-73] led to a reexamination of previous models.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Properties of the NAD(P)H-dependent xylose reductase from the xylose-fermenting yeast Pichia stipitis.

Xylose reductase from the xylose-fermenting yeast Pichia stipitis was purified to electrophoretic and spectral homogeneity via ion-exchange, affinity and high-performance gel chromatography. The enzyme was active with various aldose substrates, such as DL-glyceraldehyde, L-arabinose, D-xylose, D-ribose, D-galactose and D-glucose. Hence the xylose reductase of Pichia stipitis is an aldose reductase (EC 1.1.1.21). Unlike all aldose reductases characterized so far, the enzyme from this yeast was active with both NADPH and NADH as coenzyme. The activity with NADH was approx. 70% of that with NADPH for the various aldose substrates. NADP+ was a potent inhibitor of both the NADPH- and NADH-linked xylose reduction, whereas NAD+ showed strong inhibition only with the NADH-linked reaction. These results are discussed in the context of the possible use of Pichia stipitis and similar yeasts for the anaerobic conversion of xylose into ethanol.

Aldehyde Reductase↗
PubMed1985

The layered organization of nucleosomes in 30 nm chromatin fibers.

We have used electron microscopy and established methods of three-dimensional reconstruction to obtain structural information on the 30 nm chromatin fibers from sea cucumber sperm and chicken erythrocytes. The fibers show a longitudinal periodicity of 10-11 nm. We have interpreted this periodicity as due to a grouping of nucleosomes into disks, each disk containing about 5-6 nucleosomes. These disks are closely stacked to form the chromatin fiber. We have built a detailed model for four fibers and we have determined the approximate coordinates of all the nucleosomes in them. The average distance found between neighboring nucleosomes has a value close to 11 nm. They may be connected either as a regularly distorted helix or as a layered zigzag. The second model appears more appropriate, since in the constrictions of the fibers the nucleosomes can only be connected as a zigzag.

Animals↗
PubMed1985

Shape changes and polarization of cells migrating through tissue. A high-voltage electron microscope and computer graphics study of serial thick sections.

Structural changes of carcinoma cells and fibroblasts migrating through small spaces in the elastic-collagen reticulum of mouse peritoneum have been studied by high-voltage electron microscopy of serial thick sections and by computer graphics reconstruction of cell profiles. The change of shape profile of an individual cell, between serial sections is large and the distribution of organelles is very non-uniform and changes markedly between sections. Conclusions about adhesion, intercell contact, cell shape and polarization of cytoplasmic organelles could only be reached by assessing a complete set of serial sections. Our preliminary results suggest that interesting structural changes occur in both carcinoma cells and fibroblasts when migrating through this tissue.

Adenocarcinoma↗
PubMed1985

Use of nonlinear mapping in multivariate image analysis of molecule projections.

A nonlinear mapping algorithm has been designed for the statistical analysis of sets of images in electron microscopy. The algorithm is appropriate in situations where it is not isolated features that determine the clustering or trends in the data set but a combination of several simultaneously changing features. The combination of the nonlinear mapping algorithm with correspondence analysis offers a way of ordering a set of images according to the variations of a single feature, as well as according to the combined variation of several independent features. The application of the combined algorithms ranges from image selection for averaging procedures to the sorting of images, that inherently form a tilt series. These sorted images then can be used for the three-dimensional reconstruction of macromolecules.

Animals↗
PubMed1985

Investigation of the 50 S ribosomal subunit by electron microscopy and image analysis.

In electron micrographs of 50 S (large) subunits from Escherichia coli ribosomes, the highly preferred crown view is inferred to represent the roughly hemispherical particle lying with its flat or concave face against the carbon film. Single particle averaging allows the reproducible details of the crown view particle to be recognized. Multivariate image analysis shows the most variable morphological features of this view to be the two side protrusions, the L7/L12 stalk and the L1 ridge, both of which show apparent positional variations. The invariance of the features of the particle body implies that the movements of the side protrusions are not merely a result of perspective changes produced by major rotations of the particle body out of its quasistable, flat-lying position. A bending point localized on the L7/L12 stalk is conjectured to represent a functional "hinge" that may be related to the secondary/tertiary structure of the L7/L12 dimeric protein.

Escherichia coli↗
PubMed1985

Analysis of the irregular planar distribution of proteins in membranes.

Methods to characterize the irregular but non-random planar distribution of proteins in biological membranes were investigated. The distribution of the proteins constituting the intramembranous particles (IMP) in human erythrocyte membranes was used as an example. The distribution of IMPs was deliberately altered by experimental means. For real space analyses, the IMP positions in freeze fracture micrograph S were determined by an automatic procedure described. Radial distribution and autocorrelation analysis revealed quantitative differences between experimental groups. These methods are more sensitive than the corresponding optical diffraction or Fourier-Bessel analyses of the same IMP distribution data, due to the inability of the diffraction methods to separate contrast and distribution effects. A method to identify IMPs on a non-uniform background is described.

Erythrocyte Membrane↗
PubMed1985

The structure of the stalk surface layer of a brine pond microorganism: correlation averaging applied to a double layered lattice structure.

The surface layer of the stalk of a prosthecate halophilic microorganism is a periodic array (space group p3m1) comprised of electron dense trimers with a centre to centre spacing of 9.0 nm. The structure is reminiscent of E. coli porin. We have demonstrated that the method of correlation averaging can be effectively used to separate overlapping lattices, and that this results in a higher fidelity reconstruction, when compared to the established method of Fourier filtration. Two statistical methods are used to determine the resolution of the correlation average as a function of the number of 'windows' averaged. (i) The phase residual of spatial frequencies in Fourier space is computed between independently obtained subaverages, and (ii) a new method of Q factor analysis examines the cumulative vector sum in Fourier space as a function of the number of windows averaged. Both methods give a resolution of 1/2.1 nm-1.

Bacteria↗