Biomedical subjects

J Arnold

Publications and source records attributed to J Arnold.

At least 289 records · Page 16Linked to original sources

PubMedDate not supplied

Comparison of the nucleotide sequence of soybean 18S rRNA with the sequences of other small-subunit rRNAs.

We present the sequence of the nuclear-encoded ribosomal small-subunit RNA from soybean. The soybean 18S rRNA sequence of 1807 nucleotides (nt) is contained in a gene family of approximately 800 closely related members per haploid genome. This sequence is compared with the ribosomal small-subunit RNAs of maize (1805 nt), yeast (1789 nt), Xenopus (1825 nt), rat (1869 nt), and Escherichia coli (1541 nt). Significant sequence homology is observed among the eukaryotic small-subunit rRNAs examined, and some sequence homology is observed between eukaryotic and prokaryotic small-subunit rRNAs. Conserved regions are found to be interspersed among highly diverged sequences. The significance of these comparisons is evaluated using computer simulation of a random sequence model. A tentative model of the secondary structure of soybean 18S rRNA is presented and discussed in the context of the functions of the various conserved regions within the sequence. On the basis of this model, the short base-paired sequences defining the four structural and functional domains of all 18S rRNAs are seen to be well conserved. The potential roles of other conserved soybean 18S rRNA sequences in protein synthesis are discussed.

Animals↗

PubMedDate not supplied

Maxillary ameloblastoma: case report.

Ameloblastoma of the maxilla is an unusual epithelial tumor of odontogenic origin. Although it is considered benign, it can behave in a slowly growing infiltrative fashion, with multiple recurrences and eventual intracranial, or even distant, spread. Information on this tumor consists, to a large extent, of case reports presented in the oral surgery literature. This study is a retrospective review of our combined institutional experience with nasomaxillary tumors from 1980 to 1988. Among these cases were four patients with maxillary ameloblastoma, two males and two females, ranging in age from 16 to 66 years at presentation. Disease extent varied from ameloblastoma localized to a cyst in the maxillary sinus to extensive maxillary and ethmoid involvement. Follow-up ranged from 2 to 13 years, and disease course varied from apparent disease control to persistent intracranial tumor, despite attempts at extirpation. An analysis of this experience and the related literature is presented, along with recommendations for radical therapy, when appropriate, to best ensure control.

Adolescent↗

PubMedDate not supplied

Exclusive measurements of light fragment production at forward angles in Ne-Pb and Ne-NaF collisions at E/A=400 MeV and 800 MeV.

Emission of light fragments at small angles is studied in relativistic heavy ion collisions using the Diogene plastic wall for both symmetrical and non-symmetrical target-projectile systems with 400 MeV per nucleon and 800 MeV per nucleon incident neon nuclei. Efficiency of multiplicity measurements in the small angle range for the selection of central or peripheral collisions is confirmed for asymmetric systems. Differential production cross sections of Z = 1 fragments show evidence for the existence of two emitting sources. The apparent temperature of each source is obtained from comparison with a thermodynamical model.

Elementary Particles↗

PubMedDate not supplied

Diabetic retinopathy: I. The measurement of intercapillary area in normal retinal angiograms.

A method for the quantitation of areas of non-perfusion of retinal angiograms is described. The values for the area of the foveal avascular zone (FAZ) and the intercapillary areas in the perifoveal region of ten angiograms of normal subjects were determined. The reproducibility of measurement between and within observers was good, correlation coefficients being 0.9963 and 0.9945, respectively, for the FAZ. The inter- and intra-observer coefficients of correlation for the perifoveal intercapillary areas were 0.9284 and 0.8687, respectively. The upper limit of normal intercapillary area was determined to be 0.07 mm2 in the first degree from the FAZ, 0.04 mm2 in the second degree and 0.025 mm2 elsewhere in the macular field.

Capillaries↗

PubMedDate not supplied

Diabetic retinopathy: II. Assessment of severity and progression from fluorescein angiograms.

A quantitative method for assessing the severity of retinopathy from fluorescein angiograms was applied to a group of patients starting continuous subcutaneous insulin infusion. There was a highly significant correlation between the area of nonperfusion as measured in the 20 degrees field centered on the right macula, and the mean retinopathy score derived by a standard method from a color retinal photographic survey. In those subjects who deteriorated more, there was an increase in the nonperfused areas, whereas the foveal avascular zone remained unchanged.

Adult↗

PubMedDate not supplied

Toxic shock syndrome originating from the foot.

The most familiar etiology of toxic shock syndrome (TSS) is that of menstruation and tampon use. Nonmenstrual TSS has been described in all types of wounds including postsurgical, respiratory infection, mucous membrane disruption, burns, and vesicular lesions caused by varicella and shingles. A case of TSS occurring in a diabetic male patient with foot blisters is presented. Early recognition by an infectious disease specialist and appropriate medical management led to complete recovery. There have been no reported cases of Staphylococcus aureus TSS originating in the foot to date.

Adult↗

PubMedDate not supplied

The effects of unidirectional incompatibility on cytonuclear disequilibria in a hybrid zone.

Unidirectional incompatibility selection is examined as an alternate mechanism of natural selection to cytoplasmic male sterility (CMS) for generating cytonuclear disequilibria. Differences in the dynamics and equilibrium behavior of cytonuclear disequilibria between these two cytonuclear selection models may allow for statistical tests of CMS vs. unidirectional incompatibility between mating cytotypes. Unlike CMS without migration, unidirectional incompatibility causes the cytoplasmic allele frequency to change over time rather than remain constant, and the nuclear allele frequencies hitchhike on the cytoplasmic frequencies. The decay of disequilibria is also distinctive in the absence of migration. Furthermore, in comparing both models with migration it is seen that the opportunity for internal equilibrium can be two or three times higher in a unidirectional incompatibility vs. CMS model. An example is presented that shows how unidirectional incompatibility can be statistically eliminated as a possible mechanism of cytonuclear selection.

Alleles↗

PubMedDate not supplied