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Biomedical subjects

W A Miller

Publications and source records attributed to W A Miller.

At least 55 records · Page 3Linked to original sources
PubMed1994

Mandible bone resorption as determined from panoramic radiographs in edentulous male individuals ages 25-80 years.

Routine panoramic radiographs of 173 healthy edentulous males, aged 25-80 years, were measured for estimated bone loss using the Wical and Swoope (1974) technique. Results using this simple technique were comparable to other studies using more sophisticated methods but did not require exposure to additional radiation. Mean ratios of height of mandible (indicative of mandibular bone loss) decreased both with age of subject and with time after extraction. Efforts should be made to determine the usefulness of such archival radiographic films for a variety of studies.

Adult↗
PubMed1994

Oral status and well-being of home delivered meal recipients.

The relationship between oral health status and well-being of community dwelling frail elders was studied through questionnaires delivered to and filled out by 592 elders receiving home delivered meals. Oral status covered oral function, dental problems, oral hygiene practices and appliance use in the sample. Oral status was measured in a sub sample of 50 subjects given an oral examination, using the criteria above and soft tissue status. Plaque, calculus, and caries were measured in dentate subjects of the sub sample. Well-being was measured using standardised scales. The results indicate that oral status was related to well-being status.

Adult↗
PubMed1994

Molecular cytogenetic characterization of two types of chromosome 9 variants.

Structural variations in the pericentromeric region of chromosome 9 are common. Molecular cytogenetic characterization of two types of rare variants, each studied in two families, are reported. For convenience, the variants are designated as types 2 and 3. Type 2 variants contain an additional G-positive band in the short arm near the centromere. Type 3 variants have heterochromatin both above and below the centromere in addition to having an additional G-positive band in the short arm immediately distal to the heterochromatin. Fluorescence in situ hybridization using alpha-satellite and D9Z5 beta-satellite probes revealed two clear hybridization signals in type 3 variants, one corresponding to the position of the centromere and the other to the position of the additional G-positive band. Results of type 2 variants are less conclusive, probably due to the close proximity of the additional band to the centromere, but are suggestive of additional hybridization in proximal 9p. Our finding suggests that the type 3 variant, and possibly the type 2 variant, may represent dicentric chromosomes that are functionally stable and phenotypically inconsequential.

Chromosome Banding↗
PubMed1994

Left ventricular echogenic focus in the fetal heart: pathologic correlation.

Echogenic foci within the left ventricle of the heart have been found in a minority of fetuses and generally are believed to be a normal variant. The cause and exact location of these foci have remained speculative, however. We identified three fetuses with this sonographic finding in whom pathologic correlation was available. The only consistent histologic finding present in all three fetuses was mineralization within a papillary muscle; the chordae tendineae were normal. One of the three fetuses had trisomy 21. Echogenic foci within the left ventricle of the fetal heart represent papillary muscle mineralization. Until more data are available to investigate any possible association with aneuploidy, an echogenic focus in the left ventricle should still be considered a normal variant.

Adult↗
PubMed1993

The effect of fetal gender on the prediction of Down syndrome by means of maternal serum alpha-fetoprotein and ultrasonographic parameters.

OBJECTIVE: Our investigation was designed to use maternal serum alpha-fetoprotein and individual or combinations of ultrasonographic parameters to examine the influence of fetal gender on the prediction of Down syndrome. STUDY DESIGN: A cohort study of 5114 patients who underwent karyotype analysis between 13 and 22 weeks' gestation was undertaken. Maternal demographic variables, anthropometric indices, and maternal serum alpha-fetoprotein values were assessed. Fetal parameters recorded included gender, biparietal diameter, head circumference, femoral and humeral length, transverse cerebellar diameter, and nuchal fold thickness. The effect of fetal gender on maternal serum alpha-fetoprotein values and ultrasonographic parameters was assessed. Gender-specific differences between fetuses with Down syndrome and euploid fetuses were identified, and the optimal cutoff values of individual and combinations of biometric parameters were determined by receiver operating characteristic curve analysis. RESULTS: A total of 42 fetuses with Down syndrome were identified. Female fetuses with Down syndrome had significantly lower maternal serum alpha-fetoprotein values than their male counterparts, and maternal serum alpha-fetoprotein screening paradigms resulted in the disproportionate identification of affected female fetuses. A nuchal fold thickness > or = 5 mm was the single best ultrasonographic predictor of Down syndrome independent of fetal gender. Affected male fetuses had significantly smaller mean femoral and humeral lengths than euploid fetuses after adjustment for biparietal diameter, but only the humeral length proved a clinically useful predictor of Down syndrome. Pearson's correlation coefficient confirmed that nuchal fold thickness and humeral length were independent of each other and of maternal age and maternal serum alpha-fetoprotein levels. The optimal ultrasonographic predictor of Down syndrome was the presence of either a nuchal fold thickness > or = 6 mm or a humeral length > 3.5 to 3.7 mm below the expected value. This combination of ultrasonographic findings identified 41.7% of female and 66.7% of male fetuses with Down syndrome. CONCLUSIONS: Fetal gender affects the prediction of Down syndrome by both maternal serum alpha-fetoprotein and ultrasonographic parameters. Moreover, the ultrasonographic detection of Down syndrome in fetuses is greatly improved by a combination of gender-specific biometric parameters.

Adult↗
PubMed1993

Control of start codon choice on a plant viral RNA encoding overlapping genes.

The signals that control initiation of translation in plants are not well understood. To dissect some of these signals, we used a plant viral mRNA on which protein synthesis initiates at two out-of-frame start codons. On the large subgenomic RNA (sgRNA1) of barley yellow dwarf virus-PAV serotype, the coat protein (CP) and overlapping 17K open reading frames (ORFs) are translated beginning at the first and second AUG codons, respectively. The roles of bases at positions -3 and +4 relative to the AUG codons in efficiency of translation initiation were investigated by translation of sgRNA1 mutants in a cell-free extract and by expression of a reporter gene from mutant sgRNA1 leaders in protoplasts. The effects of mutations that disrupted and restored secondary structure encompassing the CP AUG independently of, and in combination with, changes to bases -3 and +4 were also examined. Partial digestion of the 5' end of the sgRNA1 leader with structure-sensitive nucleases gave products that were consistent with the predicted secondary structure. Secondary structure had an overall inhibitory effect on translation of both ORFs. In general, the "Kozak rules" of start codon preference predominate in determining start codon choice. Unexpectedly, for a given CP AUG sequence context, changes that decreased initiation at the downstream 17K AUG also reduced initiation at the CP AUG. To explain this observation, we propose a new model in which pausing of the ribosome at the second AUG allows increased initiation at the first AUG. This detailed analysis of the roles of primary and secondary structure in controlling translation initiation should be of value for understanding expression of any plant gene and in the design of artificial constructs.

Animals↗
PubMed1992

Pericentric inversion of chromosome 16 in a large kindred: spectrum of morbidity and mortality in offspring.

Constitutional pericentric inversions of chromosome 16 are rare in the general population. We report here a large kindred who carry an inv(16)(p13q22) rearrangement. In general, individuals with the inv(16) are in good health but prone to reproductive loss. Two different types of recombinant offspring were identified in this family and analyzed at the molecular level using probes from the alpha-globin and polycystic kidney disease loci. Both were associated with serious major malformations.

Chromosome Aberrations↗
PubMed1992

Translational frameshifting mediated by a viral sequence in plant cells.

It has been proposed that the polymerase gene of barley yellow dwarf virus and related viruses is expressed by a ribosomal frameshift event during translation. The 5' end of this gene overlaps with the 3' end of an upstream gene that is in a different reading frame. The region of overlap is similar to sequences in retro- and coronaviruses that are known to express their polymerase genes by frameshifting. This overlap region includes a "shifty" heptanucleotide, followed by a highly structured region that may contain a pseudoknot. Sequences of 115 or 144 base pairs that span this region from barley yellow dwarf virus (PAV serotype) genomic RNA were introduced into a plasmid, so that a reporter gene could be expressed in plant cells only if a minus one (-1) frameshift event occurred. Frameshifting was detected at a rate of approximately 1%. This frameshifting was abolished when the stop codon at the 3' end of the upstream open reading frame was deleted. A sequence expected to form a strong stem-loop immediately upstream of the frameshift site was unnecessary for frameshifting, and initiation at AUG codons within the stem-loop appeared to be inhibited. Like viruses that infect hosts in other kingdoms, plant viruses also can induce frameshifting in translation of their genes.

Amino Acid Sequence↗
PubMed1992

Precise mapping and in vitro translation of a trifunctional subgenomic RNA of barley yellow dwarf virus.

The barley yellow dwarf virus genome consists of a single 5.7-kb RNA encoding six open reading frames (ORFs). The four ORFs in the 3' half of the genome were proposed to be expressed via subgenomic mRNAs. Here, we show that the PAV serotype of barley yellow dwarf virus generates two subgenomic RNAs of 2.9 and 0.8 kb in infected plants and protoplasts. The 5' end of the larger subgenomic RNA (sgRNA1) was precisely mapped to base 2769 by ribonuclease protection and primer extension methods. Synthetic sgRNA1, containing the exact 5' and 3' ends, was generated by in vitro transcription, translated in vitro, and shown to serve as a message for three ORFs. Translation initiated at the first two AUG codons in sgRNA1, yielding the 22-kDa viral coat protein (CP) and a 17-kDa protein encoded by an overlapping, out-of-frame ORF. In addition, readthrough of the amber stop codon of the CP ORF gave rise to a 72-kDa fusion product of the CP ORF and an in-frame 50K ORF immediately 3' of the CP termination codon. The 0.8-kb sgRNA2 was present in greater abundance than sgRNA1 and likely serves as a message for a 6.7K ORF at the 3' end of the genome. Sequences that may control subgenomic RNA synthesis and the translational events are compared with those of other plant viruses.

Base Sequence↗
PubMed1992

Oral status and resident well-being in a skilled nursing facility population.

We studied the relationship between oral status and well-being in dentate and edentulous institutionalized residents through interviews with and dental examinations on 58 men and women. Oral status (measured by oral function, dental problem self report, soft tissue anomalies, and dry mouth) and well-being (measured by affect balance, self-esteem, health status, and nurse's ratings) were similar for dentate and edentulous subjects. Multiple regression analyses indicated oral status was significantly related to well-being. Unexpectedly, the extent of caries and plaque was also positively related to well-being, suggesting complex relationships between oral status markers and well-being in institutional settings.

Aged↗
PubMed1992

Complete nucleotide sequences of two soybean mosaic virus strains differentiated by response of soybean containing the Rsv resistance gene.

The complete nucleotide sequence of the genomic RNAs of strains G2 and G7 of soybean mosaic virus were determined. In both cases, the genome is 9588 nucleotides long, excluding the 3'-terminal poly(A) sequence. A large open reading frame (nucleotides 132 to 9329) encodes a polyprotein of 3066 amino acids with a predicted M(r) of either 349542 (strain G2) or 349741 (strain G7). Based on comparison with the proposed locations of cleavage sites of other potyvirus polyproteins, nine mature proteins are predicted. The mature proteins of the two strains share 94 to 100% amino acid identity, with the greatest variability occurring in the 35K and 42K proteins. Differences in local net charge in portions of these proteins as well as differences in amino acid sequence throughout the genome are discussed in relation to resistance and susceptibility of host plants to strains G2 and G7. Comparison with other potyviruses may be useful for taxonomic clarification of viruses and strains.

Amino Acid Sequence↗
PubMed1992

Early amniocentesis.

Early amniocentesis (EA) refers to any genetic amniocentesis performed prior to 15 weeks, 0 days' gestation. Because of technical problems, most practitioners stopped doing amniocenteses prior to 15 weeks' gestation in the late 1970s. The development of ultrasound-monitored needle insertion has allowed improved success and safety of sampling at earlier gestations, and improvements in laboratory techniques have allowed a high degree of success in culturing and processing low-volume samples. We present information on 1,805 early amniocenteses, of which 35% were performed prior to 14 weeks, 0 days' gestation. Our data indicate that with operator experience the success rate of the procedure can be similar to that seen with routine amniocentesis and that laboratory experience is not different from that with routine amniocentesis (RA) as measured by culture success, time to completion and accuracy. Pregnancy outcome, as measured by the gestational age at delivery, mode of delivery, birth weight and Apgar score, is indistinguishable between RA and EA patients. Although a randomized study is needed to accurately evaluate the fetal loss rate, the rate of birth defects and incidence of neonatal complications associated with EA procedures and examination of the crude rates for the above three parameters show that they compare favorably to the rates reported for patients who have undergone chorionic villus sampling or RA.

Abortion, Spontaneous↗
PubMed1991

Alternative tertiary structure attenuates self-cleavage of the ribozyme in the satellite RNA of barley yellow dwarf virus.

A self-cleaving satellite RNA associated with barley yellow dwarf virus (sBYDV) contains a sequence predicted to form a secondary structure similar to catalytic RNA molecules (ribozymes) of the 'hammerhead' class (Miller et al., 1991, Virology 183, 711-720). However, this RNA differs from other naturally occurring hammerheads both in its very slow cleavage rate, and in some aspects of its structure. One striking structural difference is that an additional helix is predicted that may be part of an unusual pseudoknot containing three stacked helices. Nucleotide substitutions that prevent formation of the additional helix and favor the hammerhead increased the self-cleavage rate up to 400-fold. Compensatory substitutions, predicted to restore the additional helix, reduced the self-cleavage rate by an extent proportional to the calculated stability of the helix. Partial digestion of the RNA with structure-sensitive nucleases supported the existence of the proposed alternative structure in the wildtype sequence, and formation of the hammerhead in the rapidly-cleaving mutants. This tertiary interaction may serve as a molecular switch that controls the rate of self-cleavage and possibly other functions of the satellite RNA.

Autoradiography↗
PubMed1991

Amniotic fluid contains tissue factor, a potent initiator of coagulation.

A primary clinical manifestation of amniotic fluid embolism is coagulopathy. Prior studies have identified a poorly characterized yet potent procoagulant property in amniotic fluid that increases with gestational age. One possible source of procoagulant activity is tissue factor, a primary biologic initiator of coagulation. We used sensitive immunoassays and functional assays to identify substantial quantities of tissue factor antigen and tissue factor-specific procoagulant activity in amniotic fluid, which increased with gestational age. Moreover, tissue factor accounted for virtually all of the coagulant potential of amniotic fluid. Amniotic tissue factor appeared intact and membrane bound and, when reconstituted into synthetic microvesicles of optimal phospholipid content, displayed nearly full activity. Calcium chelation and sonication experiments suggested that the presence of inhibitors and the physical configuration of membrane-bound tissue factor in amniotic fluid might explain the modest reduction in tissue factor procoagulant activity relative to total antigen levels observed in vivo. We postulate that the substantial quantities of functionally active tissue factor in amniotic fluid account for the coagulation changes accompanying amniotic fluid embolism and could indirectly contribute to the characteristic hemodynamic derangements of amniotic fluid embolism.

Amnion↗