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At least 595 records · Page 33Linked to original sources
PubMed1987

Alterations in select immunologic parameters following total artificial heart implantation.

We examined select immunologic parameters in three recipients of a total artificial heart and correlated changes with the clinical course. Two patients remain alive and were studied for 320 and 240 days, respectively; the third died 10 days after implantation. All patients demonstrated transient complement activation immediately postoperatively, as indicated by an increase in plasma levels of C3a des Arg. In the two long-term survivors, C3a des Arg levels again increased, concomitant with intravascular hemolysis associated with high blood shear rates imposed by the drive system of the heart. All three patients had a marked lymphopenia immediately postoperatively, and the two long-term survivors demonstrated marked fluctuations in total lymphocyte count. There was a progressive decline in the number of peripheral blood helper/inducer T cells in the two long-term survivors. A large number of activated (HLA-DR positive) suppressor/cytotoxic T cells were also noted in these two patients. A progressive decrease in B cells was also observed; however, total IgG and IgM levels were not decreased. No changes in neutrophil phagocytic or respiratory burst capacities were identified. The cause of these changes in lymphocyte populations is not clear; however, they may have impact on the use of this device as a bridge to transplantation and may lead to decreased immunocompetence during long-term use.

Blood Transfusion↗
PubMed1989

[Selection error of upper anterior artificial teeth].

Seventy two cases of selection error of upper anterior artificial teeth due to the esthetic factors were investigated out of the 1,507 cases of removable dentures, which were made at the Prosthodontics department of Nihon University school of dentistry at Matsudo for 17 years from November, 1971 to November, 1988. The following were the results of the investigation. 1. Frequency of the selection errors amounted to 4.8% of the total selected cases as broken down in 1.6% by Shade and 4.0% by Mould, the rate of selection errors of the Mould being significantly high. 2. By Mould, selection errors in Ovoid type occupied a significantly high rate. 3. Regarding frequency of Mould after re-selection ST and TO occupied a high rate of 45.9%. 4. Mould of re-selection were almost uniformly small, showing a trend of intumescence becoming emphatically.

Denture, Partial, Removable↗
PubMed1997

Genetic selection strategies--population genetics.

This paper provides an overview of the association between population genetics and selection strategies in poultry. Relationships between artificial and natural selection and among causes contributing to limits to artificial selection are discussed. Homeostasis and resource allocations at the individual and at the population level are reviewed. Examples from poultry demonstrate where human intervention has circumvented biological limits. Lastly, this paper considers the role of population genetics in future breeding strategies for poultry.

Animal Husbandry↗
PubMed1996

Maxillary arch and central incisor dimensions of an ethnic Chinese population in relation to complete denture prosthodontics.

In the absence of pre-extraction records, investigators have used various methods to aid in the selection and placement of artificial teeth for complete dentures. Natural tooth position and size provide the dentist with an optimal guide. A study was conducted on a group of ethnic Chinese subjects where direct measurements were made of the arch size and width of the maxillary central incisor on stone casts. The anterior arch width represented by the inter-canine cusp tip distance was 35.74 +/- 2.17mm. The mesiodistal diameter of the maxillary central incisor was 8.85 +/- 0.59mm with a range of 7.60mm to 11.20mm. The results of this study was discussed against other findings on the Caucasian, Nigerian and Malay groups. The significance of artificial tooth selection for dentures was highlighted in relation to the results obtained from the study for the group of Chinese and other races.

Adolescent↗
PubMed1988

Selective cell transplantation using bioabsorbable artificial polymers as matrices.

To date, selective cell transplantation has involved injecting cell suspensions into tissues or the vascular system. This study describes attaching cell preparations to bioerodable artificial polymers in cell culture and then implanting this polymer-cell scaffold into animals. Using standard techniques of cell harvest, single cells and clusters of fetal and adult rat and mouse hepatocytes, pancreatic islet cells, and small intestinal cells have been seeded onto biodegradable polymers of polyglactin 910, polyanhydrides, and polyorthoester. Sixty-five fetuses and 14 adult animals served as donors. One hundred fifteen polymer scaffolds were implanted into 70 recipient animals: 66 seeded with hepatocytes; 23 with intestinal cells and clusters; and 26 with pancreatic islet preparations. The cells remained viable in culture, and in the case of fetal intestine and fetal hepatocytes, appeared to proliferate while on the polymer. After four days in culture, the cell-polymer scaffolds were implanted into host animals, either in the omentum, the interscapular fat pad, or the mesentery. In three cases of fetal intestinal implantation coupled with partial hepatectomy, successful engraftment occurred in the omentum, one forming a visible 6.0 mm cyst. Three cases of hepatocyte implantation, one using adult cells and two using fetal cells, have also engrafted, showing viability of hepatocytes, mitotic figures, and vascularization of the cell mass. To date, no pancreatic islets have survived implantation. This method of cell transplantation, which we have termed "chimeric neomorphogenesis," is an alternative to current methods and requires further study.

Animals↗
PubMed1997

CASA as an aid to selecting sperm suspensions for artificial insemination in Callithrix jacchus.

The ability to use sperm motility parameters, obtained by computer-assisted sperm motility analysis (CASA), as an aid to selecting sperm samples for artificial insemination (AI) would have considerable benefits for commercial organizations and for the captive breeding of endangered species. In this study the Hobson sperm tracker (HST) was validated for use with spermatozoa from Callithrix jacchus, the common marmoset, by comparing values for straight line velocity by CASA with those obtained by direct measurement of sperm tracks. Using the settings established during validation, ejaculated and epididymal spermatozoa were analysed with the HST. The range of values for velocity parameters were used to establish expected motility profiles for the two types of spermatozoa as follows: for epididymal spermatozoa (concentration 2.2 - 85.8 x 10(6) spermatozoa/mL) VCL 109.8-155.9, VSL 75.2-141.5, VAP 85.8-142.1, MAD 13.7-40.7, ALH 3.8-7.8, BCF 1.4-4.2, LIN 40.5-91.1% and STR 70.1-97.1%; for ejaculated spermatozoa (concentration 3.2-82.0 x 10(6) spermatozoa/mL) VCL 89.6-136.7, VSL 69.6-110.3, VAP 74.5-121.9, MAD 19.2-29.3, ALH 3.0-9.9, BCF 2.8-5.5., LIN 65.4-85.3% and STR 93.8-97.7%. Epididymal spermatozoa from males which were not sexually active had significantly lower values for VCL, VSL and VAP, while values for MAD were significantly higher than for spermatozoa from sexually active males (p < 0.031). Sperm concentration affected motility parameters significantly. Although motility parameters differed according to the batch of medium used, the differences were not statistically significant. Epididymal sperm samples had significantly higher VCL, VSL and VAP but lower BCF and LIN than ejaculated sperm samples of the same concentration diluted in the same batch of medium, while MAD, ALH and STR were not different. Urine contamination significantly reduced VCL, VSL and VAP (p < 0.008, < 0.016 and < 0.008, respectively, sample size = 7) whereas MAD, ALH, BCF, LIN and STR were not affected. Therefore CASA could be useful in screening ejaculates for use in Al to eliminate samples with unusual motility patterns.

Animals↗
PubMedDate not supplied

Variable selection for QSAR by artificial ant colony systems.

Derivation of quantitative structure-activity relationships (QSAR) usually involves computational models that relate a set of input variables describing the structural properties of the molecules for which the activity has been measured to the output variable representing activity. Many of the input variables may be correlated, and it is therefore often desirable to select an optimal subset of the input variables that results in the most predictive model. In this paper we describe an optimization technique for variable selection based on artificial ant colony systems. The algorithm is inspired by the behavior of real ants, which are able to find the shortest path between a food source and their nest using deposits of pheromone as a communication agent. The underlying basic self-organizing principle is exploited for the construction of parsimonious QSAR models based on neural networks for several classical QSAR data sets.

Algorithms↗
PubMed1994

Identification of Norwalk virus in artificially seeded shellfish and selected foods.

A rotavirus dsRNA purification protocol was adapted to extract Norwalk ssRNA from artificially contaminated shellfish, and a sensitive reverse transcription-polymerase chain reaction assay for Norwalk virus was devised to identify an estimated 20-200 genomic copies. The technique includes deproteinization with guanidinium isothiocyanate, adsorption of RNA to hydroxyapatite, and sequential precipitation with cetyltrimethylammonium bromide and ethanol. The protocol allows high recovery of viral RNA free of enzymatic inhibitors from oysters, clams, and a variety of food matrices. Norwalk virus sequences were copied and amplified by using primers selected from the polymerase gene. Digestion of the amplified products with restriction enzymes ensured the specificity of the test. This rapid and sensitive assay may significantly improve the prospect for the routine screening of the uncultivatable Norwalk virus in food stuffs.

Animals↗
PubMed1997

Two vectors for the insertion of mammalian selectable genes into yeast artificial chromosome cloned DNA.

The introduction of cloned DNA into mammalian cells allows functional testing of genes contained on the fragments. In many cases, the exogenous DNA introduced into mammalian cells requires selectable genes that mark the presence of input DNA. Two new vectors, carrying mammalian selectable markers encoding for either neomycin-resistance (neo) or histidinol-resistance (hol), have been constructed for targeted integration to specific single-copy sites within yeast artificial chromosome (YAC) insert DNA. The integration cassettes comprise a single selectable yeast gene adjacent to a mammalian selectable gene, either LEU2 with neo or HIS3 with hol. Modification of the YAC occurs in yeast by transfection with linear DNA containing YAC-specific, unique, recombinogenic ends, thereby ensuring co-integration of the markers. Analysis of modified YACs confirms that both vectors correctly integrate into the targeted unique sites. The precise localization of selectable marker genes in the cloned DNA ensures the integrity of the genomic fragments during functional testing. Placement of mammalian selectable markers within the YAC insert DNA should allow for YAC-based gene targeting experiments in a variety of mammalian cell lines.

3-Isopropylmalate Dehydrogenase↗
PubMed2001

An assessment of the ability of dental undergraduates to choose artificial teeth which are appropriate for the age and sex of the denture wearer: a pilot study.

One of the main objectives in selecting and arranging artificial teeth is to produce prostheses which defy detection. With an appropriate degree of clinical experience and expertise it should be a relatively straightforward procedure to select a suitable artificial tooth mould. However, for the relatively inexperienced dental undergraduate it can be a challenging process. The aim of this study was to assess the ability of dental undergraduates to select artificial teeth which are appropriate for the age and sex of the denture wearer. One hundred and fifty dental undergraduates aged 18-35 were asked to complete a questionnaire to assess their attitudes towards artificial tooth selection and asked to correctly identify six artificial tooth arrangements according to age and sex. The results showed that a large percentage of dental undergraduates at Bristol experience difficulty in selecting artificial teeth which are appropriate for the age and sex of the denture wearer. There is a need for improved training and guidance on artificial tooth selection and arrangement.

Adolescent↗
PubMed1995

New vectors for manipulation and selection of functional yeast artificial chromosomes (YACs) containing human DNA inserts.

A set of fragmentation vectors is described which produce a deletion series of smaller yeast artificial chromosomes (YACs) from a larger parent YAC with the insertion of a eukaryotic selectable marker. In addition, new vectors were designed to permit integration of the genes encoding neomycin (neo) or hygromycin B (hyg) resistance into YACs containing inserts of human DNA. All these vectors are compatible with the yeast host strain AB1380, in which most human genomic YAC libraries are maintained. Linearized vector DNA is used to transform yeast cells in which homologous recombination between human DNA in the YAC and the Alu sequence in the fragmentation or integrating vector produces terminal deletions from the acentromeric (URA3) end of the YAC or insertion of the vector into the YAC, respectively. A set of directional deletions of a YAC is useful for genomic mapping, restriction analysis and functional measurements of large chromosomal regions. The neo and hyg eukaryotic markers permit the study of gene function after introduction of deleted YACs into mammalian cells. Transformation of YACs with the fragmentation vectors resulted in fragmentation in 21-46% of the clones examined; transformation with the integrating vector resulted in integration in 46% of the clones examined.

Base Sequence↗
PubMed1991

Integrative selection of human chromosome-specific yeast artificial chromosomes.

Human specific "integrative selection vectors" (ISVs) were designed to optimize integration of a yeast-selectable marker specifically into yeast artificial chromosomes (YACs) derived from human but not mouse DNA. ISVs were transformed into a YAC genomic library constructed from DNA of a human-mouse somatic cell hybrid containing chromosome 21 (HSA21) as the only human chromosome. One percent of the yeast in the original library contained HSA21-derived YACs; between 45% and 54% of the yeast recovered after transformation with ISV vectors contained human YACs. Integrative selection provides a rapid means of obtaining a highly enriched population of human chromosome-specific YACs by eliminating the labor-intensive steps of isolating and screening primary transformants. The procedure is biased toward the selection of YACs that contain a large number of targets for homologous recombinations; thus, libraries constructed by this procedure will be composed primarily of the largest YACs in the population.

Chromosomes, Fungal↗
PubMed1998

Computer-generated study of the correlation between tooth, face, arch forms, and palatal contour.

STATEMENT OF PROBLEM: Several factors have been suggested as aids for artificial tooth selection. Numerous methods have been devised for the evaluation of reliable esthetic factors in determining artificial tooth form. There is no universally accepted single esthetic factor that can be used reliably to aid artificial tooth selection. PURPOSE: This article describes a new method incorporating a computer program to analyze four esthetic factors: form of the face, arch form, palatal contour, tooth shape, and to determine whether there was correlation between tooth, face, and arch forms and palatal contour. MATERIAL AND METHOD: Impressions were made of the maxillary dentition of 50 dentate undergraduate dental students with irreversible hydrocolloid impression material and casts formed. A standardized photographic procedure was used to record portrait slides of each subject's face and of maxillary dental arches and central incisors made from dental casts. A comprehensive computer program was developed to correlate esthetic factors by superimposition. RESULTS: Superimposing outline form between face, tooth, and arch showed that for tooth to face form nearly half the comparisons were dissimilar and only 22% corresponded. This is the lowest level of correspondence in this group. Highest correspondence (28%) occurred between arch to face form, followed by arch to tooth form (24%). Arch to tooth showed the lowest level of dissimilarity (32%). For correlation among the four factors across the sample group based on a comparison of classifications in each subject, men tended to dominate tapering classes, whereas women dominated square and ovoid classes. CONCLUSION: Correspondence of outline forms through superimposition revealed an insignificant correlation between face, tooth, and arch forms. Although this method applies high technology, it does not improve the accuracy of determining shape and size of teeth in an edentulous patient. The cost and complexity of the method of measurement may also make it impractical for common application.

Adult↗
PubMed1998

An artificial neural network can select patients at high risk of developing progressive IgA nephropathy more accurately than experienced nephrologists.

BACKGROUND: The object of the study was to develop an artificial neural network (ANN) to identify patients with IgA nephropathy (IgAN) with a poor prognosis and to compare the predictions of the ANN with the predictions of six experienced nephrologists. METHODS: The following data from the time of renal biopsy were retrieved from the records of 54 patients with IgAN: age, sex, systolic and diastolic blood pressure, number of prescribed antihypertensive drugs, 24-h urine protein excretion, and serum creatinine. Patients aged less than 14 years, or who had serum creatinine > 350 mumol/l at presentation, liver disease or concomitant kidney disease were excluded. Outcome was assigned as 'stable' if serum creatinine was < 150 mumol/l after 7 years and 'non-stable' if serum creatinine was > or = 150 mumol/l. The ANN was trained and tested using a 'jack-knife' sampling technique and performance evaluated in terms of number of correct predictions, sensitivity and specificity. The six nephrologists were asked to predict outcome at 7 years for each patient using the same data as the ANN and their performance was assessed in the same manner. RESULTS: The ANN assigned the correct outcome to 47/54 (87.0%) patients: sensitivity 19/22 (86.4%), specificity 28/32 (87.5%). The mean score for nephrologists was 37.5/54 (69.4%, range 35-40), mean sensitivity 72% and mean specificity 66%. CONCLUSIONS: An ANN trained using routine clinical information obtained at the time of diagnosis can potentially predict 7-year outcome for renal function in IgAN more accurately than experienced nephrologists, and can therefore identify a group of high-risk patients requiring close follow-up.

Adolescent↗
PubMed1989

[A fundamental study on the influence of posterior artificial tooth forms on denture movements during mastication].

The form of posterior artificial tooth is an essential factor related to denture stability during mastication and to masticatory ability. Generally, cusp teeth are selected out of consideration for balance during eccentric occlusion. From another viewpoint, cuspless teeth are selected to ensure stability and to prevent the occurrence of lateral vectors caused by the inclination of the occlusal facet. It has been reported, however, that the counterbalance phenomenon occurring between occlusal facets decreases the lateral vector. Moreover, cusp teeth are useful in increasing the possibility of establishing bilateral balance. Guidelines for selecting posterior artificial teeth in the production of functional dentures are diverse and cannot be said to have been firmly established yet. This model experiment, which employed complete lower dentures, was designed to provide basic information for discussing the influence of occlusal facets of cusp teeth on denture movements during mastication and to arrive at some clinical suggestions for selecting posterior artificial teeth. Artificial teeth with cusp angles of 0 degrees, 10 degrees, 20 degrees, and 30 degrees were made by adjusting setting conditions on a condylar type articulator. Four kinds of experimental dentures were made and used in measuring horizontal movements of lower dentures during the crushing of experimental food. Final phase of chewing stroke was taken into consideration in establishing two types of loading direction. One type was at 70 degrees (DL 70 degrees) to the occlusal plane on the frontal plane and from the outer side (the working side). The other type was 90 degrees (DL 90 degrees) to the occlusal plane. Maximum load was 15kg and the denture displacement was analyzed at 2kg, 4kg, 8kg and 15kg. Experimental foods were smoked cuttlefish (sectile food), raisins (food flattened under pressure), and peanuts (crushable food). Analyses were made of experimental denture movement patterns and denture displacement amounts. Results 1. Experimental denture movement patterns differed according to the nature of the experimental food. The pattern in the case of smoked cuttlefish was mainly of the C type; that is, primarily motion first to the balancing side and then to the working side. The pattern for raisins was mainly of the S type; that is, primarily motion first to the working side, then to the balancing side, and then to the working side again. Several patterns appeared in the case of peanuts.(ABSTRACT TRUNCATED AT 400 WORDS)

Bicuspid↗
PubMed2003

Synthetic artificial peptidases and nucleases using macromolecular catalytic systems.

Effective artificial enzymes have been designed by adopting macromolecular systems for catalyst-substrate complexes. Artificial active sites comprising two or more organic functional groups were built on macromolecular backbones, leading to several types of organic artificial proteases. The activity of metal centers for peptide or DNA hydrolysis was greatly enhanced by attachment to polystyrene, leading to artificial metallopeptidases with substrate selectivity as well as artificial metallonucleases with high catalytic activity for double stranded DNA. A small artificial protease selective for a macromolecular target protein was synthesized. Target-specific artificial proteases can be used as protein-cleaving catalytic drugs.

Catalysis↗
PubMed2006

Discriminating benign from malignant thyroid lesions using artificial intelligence and statistical selection of morphometric features.

The objective of this study was to perform a comparative investigation of the capability of various classifiers in discriminating benign from malignant thyroid lesions. Using May Grunvald-Giemsa-stained smears taken by fine needle aspiration (FNA) and a custom image analysis system, 25 nuclear features describing the size, shape and texture of the nuclei were measured in each case. A statistical pre-processing of features revealed that only 4 of the 25 features are important when discriminating benign from malignant thyroid lesions, which were transformed and fed to four classifiers for subsequent analysis. The cases were divided into one set used for the training of classifiers, a second set used as the test set, and the remaining cases with no clear classification formed an ambiguous test set. Classification was performed at the nuclear and patient level. The technique described in this study produced encouraging results and promises to be a helpful tool in the daily cytological laboratory routine.

Anthropometry↗