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Biomedical subjects

D A Miller

Publications and source records attributed to D A Miller.

At least 145 records · Page 8Linked to original sources
PubMed1989

Extractive ultrafiltration.

Extractive ultrafiltration is a separation process by which liquid extraction in series with ultrafiltration removes contaminants from water. The toxin is extracted into an organic-in-water emulsion which is then separated by an ultrafilter. The ultrafilter thus replaces the settler in a conventional mixer-settler process; the extraction and emulsification allow ultrafiltration to remove much smaller molecules than is indicated by the nominal molecular weight cut-off of the membrane. In the present study, the toxins, toluene and monochlorobenzene, were individually extracted from water into heptane and hexane, respectively, reducing their concentration in the permeate water five to ten fold, at fluxes in excess of 60% of the pure water flux for the membrane. The operating temperature, organic to water ratio, and amount of surfactant used to stabilize the emulsion, were independently varied to determine the optimum values of each quantity, consistent with highest possible permeate flux through the membrane and maximum removal of the contaminant. General conclusions drawn were that the optimum permeate was obtained 1. at ambient temperature 2. when surfactant concentration was a minimum 3. when a minimum amount of extraction solvent was used.

Chemical Phenomena↗
PubMed1989

A dicentric recombinant 9 derived from a paracentric inversion: phenotype, cytogenetics, and molecular analysis of centromeres.

A 4-year-old girl with multiple malformations and severe developmental delay has been shown to have a karyotype of 46,XX-9,+rec(9),dup p,inv(9) (q22.1q34.3)mat, with duplication 9pter-q22.1 and deficiency 9q34.3-qter. This case confirms that a stable recombinant chromosome can result from a paracentric inversion. The recombinant was derived by two crossovers, one within the inversion loop and a second outside the inversion loop, between 9q21 and the beginning of the meiotic inversion at 9q22.1. In 87 cells the rec(9) had one Cd-positive primary constriction. In 13 cells the rec(9) had two primary constrictions; in 12 of these cells there was one Cd-positive centromere, and in one of these cells both primary constrictions were Cd-positive. Nuclear projections were observed in 10% of fibroblast interphase cells harvested in situ, suggesting that there was some spindle-fiber activity of the "latent" centromere. In situ hybridization with a centromere-specific probe (p82H) and a satellite III probe (L6) revealed no differences between the two C-band regions of the rec(9) and the normal 9 or inverted 9 chromosomes.

Abnormalities, Multiple↗
PubMed1988

A new type of transforming growth factor-beta, TGF-beta 3.

A new type of TGF-beta, TGF-beta 3, has been identified by cDNA characterization. The amino acid sequence of mature TGF-beta 3 and its precursor has been derived from porcine and human cDNA sequences. The human TGF-beta 3 gene is spread over seven exons as in the case of the TGF-beta 1 gene. Comparison with TGF-beta 1 and -beta 2 indicates a strong conservation of the mature sequences, but a relaxed homology in the precursor segments. TGF-beta 3 mRNA is mainly expressed in cell lines from mesenchymal origin, suggesting a biological role different from the other TGFs-beta.

Amino Acid Sequence↗
PubMed1988

Relationship between the number and function of human ribosomal genes.

The relative number of ribosomal RNA genes of the acrocentric chromosomes in one individual was measured by counting grains after in situ hybridization of 3H-labeled human 18S rDNA to fixed metaphase chromosomes. The relative amount of ribosomal RNA gene activity of each of the same chromosomes was estimated by determining the frequency with which the chromosome's nucleolus organizer region (NOR) was silver stained, the size of the silver-stained region, and how often the chromosome was found in satellite association. Results were similar in phytohemagglutinin-stimulated T-lymphocytes, Epstein-Barr virus transformed lymphoblasts, and fibroblasts. One chromosome 21 had few gene copies and low activity. One chromosome 22 had many gene copies but low activity. Both chromosomes 14 had few gene copies but high activity. The level of expression that can be achieved by rRNA gene clusters can, therefore, be determined by factors other than the number of gene copies.

B-Lymphocytes↗
PubMed1988

A human-derived probe, p82H, hybridizes to the centromeres of gorilla, chimpanzee, and orangutan.

A human-derived centromeric sequence, p82H, hybridizes to DNA from gorilla, chimpanzee, pygmy chimpanzee, and orangutan. On DNA blots, multimeric ladders based on 170 or 340 bp repeat units are seen. In metaphase chromosome preparations from these species, p82H hybridizes to the centromeric region of every chromosome. p82H forms less stable hybrids with DNA from the lion-tailed macaque and does not hybridize to DNA or chromosomes of the owl monkey or the mouse.

Animals↗
PubMed1988

Isolation and nucleotide sequence of the cDNA for rat liver serine dehydratase mRNA and structures of the 5' and 3' flanking regions of the serine dehydratase gene.

Rat serine dehydratase cDNA clones were isolated from a lambda gt11 cDNA library on the basis of their reactivity with monospecific immunoglobulin to the purified enzyme. Using the cDNA insert from a clone that encoded the serine dehydratase subunit as a probe, additional clones were isolated from the same library by plaque hybridization. Nucleotide sequence analysis of the largest clone obtained showed that it has 1444 base pairs with an open reading frame consisting of 1089 base pairs. The deduced amino acid sequence contained sequences of several portions of the serine dehydratase protein, as determined by Edman degradation. Rat liver serine dehydratase mRNA virtually disappeared from livers of rats fed a protein-free diet for 5 days. Several genomic clones were isolated from two libraries. Determinations of the transcription start site and the structure of the 3' flanking region of the gene indicated that the coded mRNA is 1504 nucleotides long. The 5' promoter region contained a variety of sequences similar to several consensus sequences believed to be important for the regulation of specific gene expression.

Amino Acid Sequence↗
PubMed1988

A model to evaluate whether a community can support a physician.

A major concern to the rural citizens of the United States is the availability of health care in their community. Community leaders and physicians considering locating in rural communities need a method by which they can evaluate a community's potential for supporting a physician. A detailed survey was conducted in 1986 of 25 physicians' practices in rural Oklahoma. Data were collected from the physicians on their number of patient visits and practice costs in 1985. Using this information, the authors designed a model to project the economic feasibility of establishing a physician practice in a specific community. This model can be used to project the number of physician visits a community can generate, the costs to establish and maintain a clinic, and the gross and net income of the practice.

Adolescent↗
PubMed1988

A new serum-free medium for monoclonal antibody production.

A new serum-free, defined-protein, medium for the growth of murine hybridoma cells and the production of monoclonal antibodies has been developed. Designated WRC 935 medium, this formulation supports the growth of hybridoma cells in higher numbers, and promotes better cell viabilities and increased monoclonal antibody levels compared to growth in DMEM supplemented with 10% fetal bovine serum or in a DMEM/F-12 serum-free mixture. In suspension cultures, WRC 935 medium typically promoted cell growth to densities over two million cells per milliliter. This medium also promoted the rapid growth of cells following their transfer from liquid nitrogen storage. WRC 935 medium is especially useful for high density cell culture production methods using hollow-fiber bioreactors. Hollow-fiber bioreactors using this medium produced antibody at an average rate of 11 mg/day, and the antibody concentration ranged from 10 to 40 mg/ml.

Animals↗
PubMed1987

The human apolipoprotein C-II gene sequence contains a novel chromosome 19-specific minisatellite in its third intron.

The human apolipoprotein C-II gene was sequenced and found to contain four exons and three introns, with a major transcription initiation site located 26 base pairs downstream from a TATA sequence element. The third intron was found to be composed almost entirely of a novel 37-base pair minisatellite that is repeated six times. The minisatellite sequence was found to be present in approximately 60 different genomic locations. The minisatellite DNA sequence at three of these loci were compared and found to be highly conserved. In situ hybridization indicated that the minisatellite loci were clustered in the q13.3 band of chromosome 19. This is the first example of a chromosome- and band-specific repetitive element in the mammalian genome.

Apolipoprotein C-II↗
PubMed1987

Generation of human B-cell hybridomas secreting monoclonal anti-myelin-associated glycoprotein antibodies from a patient with neuropathy.

Human hybridomas that secrete monoclonal IgM anti-myelin-associated glycoprotein antibodies were generated by fusion with cells from a patient with peripheral neuropathy and IgM monoclonal gammopathy. Karyotypic analysis of the hybridoma cells revealed no chromosomal abnormalities. The cells were positive for cell-surface idiotype HLA-DR and the plasma cell antigen PCA-1, and negative for the B-cell determinant B4 and for Leu-1, which has been postulated to distinguish a subpopulation of B cells that secrete IgM with autoantibody activity.

Antibodies, Anti-Idiotypic↗
PubMed1987

p82H identifies sequences at every human centromere.

A cloned alphoid sequence, p82H, hybridizes in situ to the centromere of every human chromosome. After washing under stringent conditions, no more than 8% of the grains are located on any specific chromosome. p82H thus differs from other centromeric sequences which are reported to be chromosome specific, because it detects sequences that are conserved among the chromosomes. Two experimental approaches show that the p82H sequences are closely associated with the centromere. First, p82H remains with the relocated centromeres in an inv(19) and an inv(6) chromosome. Second, p82H hybridizes at the centromere but not to the centromeric heterochromatin of chromosomes 1, 9 and 16 that have elongated 1qh, 9qh and 16qh regions produced by short growth in 5-azacytidine. The only noncentromeric site of hybridization is at the distal end of the 9qh region.

Base Sequence↗
PubMed1987

Regional localization and characterization of a DNA segment on the long arm of chromosome 21.

A human genomic DNA fragment, pAM37 (HGM8; D21S22), was mapped to chromosome 21q2.1-q2.21 by in situ hybridization. This segment is therefore situated on the boundary of the "pathological region" of Down syndrome. A genomic restriction map encompassing 35 kb of chromosome 21 was derived and two restriction fragment length polymorphisms (RFLPs) were mapped and characterized. A homologous sequence was detected in the mouse genome but no homologous RNA was detected in a range of human tissues. This DNA segment will contribute to the linkage mapping of chromosome 21 and will facilitate delineation of the pathological region of Down syndrome.

Chromosome Banding↗
PubMed1987

Sound-meaning relationships in speakers of Urdu and English: evidence for a cross-cultural phonetic symbolism.

Twelve English- and 12 Urdu-speaking males, ranging in age from 18 to 30 years, were asked to assign pure-tone frequencies as a "best fit" to visually presented shapes. Six basic figures were employed (circle, ellipse, right triangle, isosceles triangle, along with two historical psycholinguistic forms--uloomu and takete) and varied on three dimensions of size, complexity, and density. The results of the study indicate that there was consistency in the assignment of pure-tone frequencies to the dimensions of the figures and that the pattern of assignment was generally similar for both English- and Urdu-speaking subjects alike. Specifically, for both language groups, round figures (circles and ellipses) were assigned significantly lower frequencies than other stimuli. Also, complex and dense figures (i.e., those designed to simulate "visual depth" and "visual texture," respectively) received significantly higher frequency settings than those stimuli not possessing these dimensions. Additional analyses revealed several factors that may have contributed to the observed pattern. For example, Urdu subjects of the English proficiency produced frequency assignments that closely resembled those of the English-speaking subjects, while subjects of low English proficiency produced a pattern that was somewhat different, particularly with regard to round, complex figures. Length of residency in the United States (6 months, 1 year, or 2 years), however, did not significantly influence frequency assignments for the Urdu subjects. These results are discussed in terms of "cross-cultural" versus "language-specific" phonetic symbolism.

Adolescent↗
PubMed1987

The effect of blood flow and diffusion impairment on pulmonary gas exchange: a computer model.

An assumption of the classical three-compartment lung model is that the physiologic shunt fraction (Qs/Qt) remains constant with changes in cardiac output (Qt). As a result, when Qt decreases, both the arterial O2 tension (PaO2) and the mixed venous O2 tension (PvO2) must also decrease. Yet observations in intact dogs with pulmonary edema and humans with the adult respiratory distress syndrome (ARDS) indicate that as Qt decreases, Qs/Qt occasionally declines while the PaO2 increases. The present study was conducted to examine these discordant observations using a computer model of pulmonary gas exchange with a diffusion impairment. A computer model of gas exchange was developed to specifically analyze the effect of changing Qt upon PaO2 and Qs/Qt in the presence of diffusion impairment. Using the classical three-compartment model of gas exchange, a diffusion impairment was inserted by a MIMIC subroutine. The results of this computer simulation indicated that in the presence of a diffusion impairment, lowering Qt caused PaO2 to increase while Qs/Qt and PvO2 decreased. These changes indicated that a diffusion impairment might account for the experimental observations of the effects of Qt on PaO2 in ARDS.

Cardiac Output↗
PubMed1987

Recognition of letters traced in the right and left palms: evidence for a process-oriented tactile asymmetry.

Three experiments were conducted to examine the relative ability of the cerebral hemispheres to identify capital letters traced in the palms of the hands. In Experiment 1, letters were presented either right side up or upside down, and the subject's task was to name the letter aloud or point to an identical letter using the stimulated hand. Analysis of the accuracy data revealed that the left palm/right hemisphere (LP/RH) performed this task significantly better than did the right palm/left hemisphere (RP/LH), particularly when the stimuli were presented in the upside-down orientation. In Experiments 2 and 3, subjects performed the same letter identification task; however, on half the trials, they were required to maintain either a spatial or verbal concurrent memory load (i.e., a 24-point Vanderplas & Garvin form or six low-imagery nouns, respectively). In the no-load condition of Experiment 2 (spatial forms), the previously observed LP/RH advantage was replicated. However, in the load condition, this LP/RH superiority was no longer in evidence. In Experiment 3 (low-imagery nouns), the presence of a concurrent verbal task had minimal impact on the previously observed performance asymmetry as the LP/RH advantage was obtained in both the no-load and load conditions. The results of the three studies taken in composite suggest that (1) the operations utilized to identify letters traced in the palms of the hands are primarily spatial in nature and (2) that the observed performance asymmetry may be attributed to a right hemisphere superiority for the analysis and codification of information along a spatial dimension. These findings are discussed in terms of a "process-oriented" model of hemispheric asymmetry.

Attention↗