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Biomedical subjects

P Siebert

Publications and source records attributed to P Siebert.

At least 19 recordsLinked to original sources
PubMed2003

Assessment of the accuracy of a three-dimensional imaging system for archiving dental study models.

OBJECTIVE: The use of stone and plaster study models is an integral part of any dental practice and is required for research. Storage of study models is problematic in terms of space and cost. Ayoub et al.(1) introduced a new technique based on the recent advances in stereophotogrammetry for archiving dental study models in a digital format. However, assessment of the accuracy of the generated three-dimensional (3D) models has not been carried out yet. It was the aim of this study to evaluate the accuracy of this technique. DESIGN: A comparative assessment between direct measurements of dental study models and measurements of computer generated 3D images of the same study models was performed. MATERIALS AND METHODS: Twenty-two dental study models stored at Glasgow Dental Hospital and School for the purposes of research were used in the study. The models were captured in three dimensions using a photostereometric technique and stored in digital format. MAIN OUTCOME MEASURES: Measurements were conducted directly on dental study models and on the computer generated 3D images using Euclidean Distance Matrix Analysis.(2) The difference between the two sets of measurements was statistically analysed using a two-sample t-test. RESULTS: The average difference between measurements of dental casts and 3D images was 0.27 mm. This difference was within the range of operator errors (0.10-0.48 mm) and was not statistically significant (P < 0.05). CONCLUSION: This study shows that it is possible to use 3D imaging to store dental study models for treatment monitoring and research with a satisfactory degree of accuracy.

Archives↗
PubMed2000

"Fluorescent timer": protein that changes color with time.

We generated a mutant of the red fluorescent protein drFP583. The mutant (E5) changes its fluorescence from green to red over time. The rate of color conversion is independent of protein concentration and therefore can be used to trace time-dependent expression. We used in vivo labeling with E5 to measure expression from the heat shock-dependent promoter in Caenorhabditis elegans and from the Otx-2 promoter in developing Xenopus embryos. Thus, E5 is a "fluorescent timer" that can be used to monitor both activation and down-regulation of target promoters on the whole-organism scale.

Animals↗
PubMed2000

Detection of differentially expressed genes in lymphomas using cDNA arrays: identification of clusterin as a new diagnostic marker for anaplastic large-cell lymphomas.

This study reports the first use of gene array technology for the identification of a tumor-specific marker in lymphoid neoplasms. The differential gene expression of 31 hematopoietic cell lines, representing most major lymphoma subgroups of B- and T-cell origin, was assessed by hybridizing labeled complementary DNA to Atlas human expression arrays containing 588 genes. Genes known to be specific for B, T, or myelomonocytic lineages were appropriately identified in the arrays, validating the general utility of this approach. One gene, clusterin, not previously known to be expressed in lymphoid neoplasms, was specifically found in all 4 anaplastic large-cell lymphoma (ALCL) cell lines, but not in any of the 27 remaining tumor lines. Using a monoclonal antibody against clusterin, its differential expression was confirmed by Western blotting and immunohistochemistry. A total of 198 primary lymphomas (representing most major lymphoma subtypes), including 36 cases of systemic ALCL, were surveyed for clusterin expression by immunohistochemistry and Western blotting. All of the 36 ALCL cases marked for clusterin, with most cases showing moderate to strong staining in the majority of neoplastic cells. Clusterin expression was not related to expression of anaplastic lymphoma kinase-1. With 2 exceptions, none of the remaining 162 non-ALCL cases marked with the clusterin antibody, including Hodgkin disease and primary cutaneous ALCL. In reactive lymphoid tissues, only follicular dendritic cells and fibroblastic reticular cells exhibited staining. Clusterin is a highly conserved glycoprotein implicated in intercellular and cell matrix interactions, regulation of the complement system, lipid transport, stress responses, and apoptosis. Although its function in ALCL is unknown, the unique expression of clusterin within this category of lymphoma provides an additional marker for the diagnosis of ALCL. This study illustrates the enormous potential of gene array technologies for diagnostic marker discovery. (Blood. 2000;96:398-404)

Biomarkers, Tumor↗
PubMed1998

A vision-based three-dimensional capture system for maxillofacial assessment and surgical planning.

We describe a vision-based three-dimensional facial data capture system designed for the planning of maxillofacial operations. We describe the system requirements and outline the methods used to develop a complete three-dimensional facial capture system. Our approach is based upon imaging the face using two stereo-pair sets of cameras. Scale-space-based stereo-matching is then used to recover correspondences between each of the captured stereo-pairs. Photogrammetric routines based on adjustment of bundles are used off-line to calibrate the system by imaging a single object that references all cameras to the same co-ordinate frame. This calibration scheme allows us to convert stereo correspondences to world points for each pair of cameras without the need for any subsequent fusion of data. Initial results show that we are able to capture key facial landmarks to within 0.5 mm.

Algorithms↗
PubMed1997

Construction of cDNA libraries from small amounts of total RNA using the suppression PCR effect.

Here we describe a method for preparing high-quality cDNA libraries from total RNA. By this method, double-stranded (ds) cDNA ligated with a specially designed ds adaptor is amplified by PCR using a modified T-primer and another primer corresponding to the outer part of the adaptor. The suppression PCR effect strongly inhibits the amplification of poly(A) RNA, thereby reducing background. This method leads to amplification of high-quality cDNA, facilitating the construction of representative cDNA libraries from as little as 10-100 ng of total RNA.

DNA, Complementary↗
PubMed1997

A three-dimensional imaging system for archiving dental study casts: a preliminary report.

Dental study casts form an essential part of patient records for both diagnostic and medicolegal purposes. Storage of study casts poses major problems because of inconvenience and cost of mass storage. Various methods for recording and storage of study casts are discussed. A new biostereometric technique for digitally recording and storing dental casts, and using the recent advances in stereophotogrammetry, is presented. Archiving dental casts in a digital format would reduce problems of mass storage and provide new benefits such as duplication of casts and use in clinical and research studies.

Archives↗
PubMed1996

Three-dimensional modeling for modern diagnosis and planning in maxillofacial surgery.

The existing methods of recording the face in three dimensions are reviewed, and a new method for three-dimensional facial modeling is introduced. The technique utilizes two stereo pairs of videocameras, a stereo pair at each side of the patient's face. The system allows rapid capture of the face in three dimensions and precise measurement of anatomic landmarks. The system can be used to capture the facial image and a cephalogram almost simultaneously, allowing more accurate superimposition of soft and hard tissues. This precision will facilitate development of the surgical treatment plan. A computer program in the early stages of development will use the data generated by this biostereometric measurement system to predict soft tissue changes following orthognathic surgery.

Cephalometry↗
PubMed1994

Preparative in situ hybridization: selection of chromosome region-specific libraries on mitotic chromosomes.

We have developed preparative in situ hybridization (Prep-ISH) of complex DNA populations to mitotic chromosomes as a means of generating chromosome region-specific DNA subpopulations. Prep-ISH is a combination of two cytogenetic techniques: in situ hybridization of DNA molecules to mitotic chromosomes and chromosome microdissection. Here, we present test cases demonstrating the feasibility of this approach on mouse and human genomes, using single nuclei, single chromosomes, or single chromosomal subregions to assess sensitivity, specificity, and representation of the Prep-ISH technique. Prep-ISH has a number of applications in studies of gene expression and genome organization, including efficient cytogenetic sorting of tissue-specific cDNAs and genomic DNA libraries. In addition, Prep-ISH is likely to dramatically reduce the number of candidate genes to aid in gene discovery efforts and to improve efficiency of developing transcription maps and YAC and cosmid contigs through defined cytogenetic regions.

Animals↗
PubMed1993

[The content of DNA, RNA and protein and the wet weight:DNA, the protein:DNA and the RNA:DNA ratio in 19 different tissues of bovine fetuses of different body weight].

In 3 groups of fetuses (n = 6 each) of cattle with a body mass of 4.18 +/- 2.1 (about 160 days old), of 9.72 +/- 0.97 (about 200 days old) and of 17.12 +/- 2.61 kg (about 230 days old) the content of DNA, RNA and protein in 19 different tissues was analysed. The wet weight:DNA-, the protein:DNA- and the RNA:DNA-ratios were calculated. The growth of the different tissues in the mentioned period of the development of the fetuses by hyperplasia and hypertrophy is discussed.

Animals↗
PubMed1993

[The behavior of hematological parameters (hemoglobin, hematocrit, leukocyte count) and clinicochemical values in plasma (glucose, total proteins, alpha-amino-N, urea, pepsinogen, ascorbic acid, Fe, Cu, Zn) and the content of ascorbic acid in liver, spleen and adrenal glands in healthy lambs and lambs infected with Haemonchus contortus and Trichostrongylus colubriformis].

In 8 healthy, noninfected lambs with an initial body weight (b. w.) of 24.79 +/- 1.16 kg as well as in 3 groups of lambs (n = 8 per group) of a similar body weight after an inoculation with 3rd stage larvae of Haemonchus contortus (2500) and Trichostrongylus colubriformis (10,000) analyses of the blood plasma were performed for 45 days thereafter. On the 37th day after infection ivermectin (0.2 mg/kg b. w.) was administered per os respectively subcutaneously to the lambs of 2 groups. After 7 and 8 days the content of ascorbic acid in the liver, the spleen and the adrenals as well as that of vitamin A in the liver was analysed. The behaviour of the values influenced by a moderate infection with trichostrongylid nematodes is discussed.

Animals↗
PubMed1993

[The content of ascorbic acid in tissues of swine fetuses and newborn piglets and in the blood plasma and tissue of swine of different ages with regard to the effect of the restriction of suckling time].

In 55, 75, 95 and 110 days old pig-fetuses as well as in newborn piglets the weight of different tissues and their content of ascorbic acid were analysed. The time for suckling of the piglets of 2 sows was restricted to 12 hours per day (= group A); the piglets of 2 sows were used as a control (= group B). The restriction of the milk intake did not influence the content of the blood plasma and of the tissues in ascorbic acid. After weaning the pigs of group A had a compensatory growth and on the 214th day after birth the same slaughter mass as that of the group B. There was no difference in the content of ascorbic acid of the tissues of the 2 groups of pigs. The significance of changes in the content of ascorbic acid in the tissues during the fetal and the postnatal growth is described.

Aging↗
PubMed1992

[The content of DNA, RNA and protein and the fresh weight:DNA, protein:DNA and RNA:DNA ratios in tissue of male calves, bulls, short-scrotum bulls and oxen during the growth period].

In male calves, in bulls, in short scrotum bulls and in oxen of different age the content of DNA, RNA and protein in various tissues (cerebrum, cerebellum, spinal cord, ventricles, lung, liver, cortex of the kidney, spleen, testicles, M. semimembranosus) was analysed. The fresh weight: DNA-, the protein: DNA- and the RNA: DNA-ratios were calculated. In the age of 78 weeks the short scrotum bulls had a body weight of 577 +/- 44, the bulls of 550 +/- 21 and the oxen of 462 +/- 41 kg. The testicles of the short scrotum bulls were smaller than that of the bulls. The differences in the content of DNA, RNA and protein per g tissue between male calves, bulls, short scrotum bulls and oxen of the same age were in part significant. The total content of DNA, of RNA and of protein for the 78 weeks old as well as the number of nuclei of the lung, the liver, the spleen and the testicles for the 6 and 78 weeks old animals were calculated. The biochemical parameters can be used for the characterization of the inhibition of growth of the different organs of calves and cattle by malnutrition and diseases.

Animals↗
PubMed1991

[The content of beta-carotene, vitamin A and ascorbic acid in different tissues of bulls, short-scrotum bulls and oxen of different body weights].

Analyses of the liver of bulls of different age show, that the concentration of beta-carotene in the age of 6 to that of 25 weeks increased only from 0.43 +/- 0.16 to 1.66 +/- 0.27 and that of vitamin A from 11.49 +/- 5.87 to 13.90 +/- 5.21 micrograms/g fresh weight. The concentration of beta-carotene and of vitamin A in the testis of bulls and of short scrotum bulls up to an age of 15 weeks was similar; thereafter the concentration in the short scrotum bulls was higher. At an age of 72 weeks the concentration of vitamin A in the liver of bulls (219.17 +/- 51.86) was higher (p less than 0.01) than in that of the short scrotum bulls (144.11 +/- 27.79) and that of the oxen (135.51 +/- 41.26 micrograms/g fresh weight). Analyses of the concentration of ascorbic acid in 8 different tissues of bulls and short scrotum bulls at 6 various periods show, that the highest values mostly were found in December.

Animals↗
PubMed1991

[Content of beta-carotene, vitamin E and ascorbic acid in blood plasma of female calves, cattle, bulls, castrates and ox throughout the course of the year].

The concentration of beta-carotin, of vitamin E and of ascorbic acid in the plasma of female calves (beginning with an age of 4 weeks), of cows in the 2nd and 5th lactation, of bulls, of short scrotum bulls and of oxes in the course of the year was analysed. The concentration of beta-carotin in the plasma of calves after driving up to pasture increased slower than that of cows. After transition to stable feeding there was a significant decrease in the concentration after 4 weeks. During the period of suckling the concentration of vitamin E in the plasma of calves was low. After transition to pasture the concentration of vitamin E in the plasma of calves increased slower than in that of the cows. The concentration of ascorbic acid in the plasma during the winter was higher than during the summer. There was no influence of experimental cryptorchism or castration on the mentioned values.

Aging↗
PubMed1991

[The content of minerals and Fe, Cu and Zn in blood plasma, in erythrocytes and in 10 different tissues of bulls, short scrotum bulls and oxen].

The concentrations of minerals (Ca, Mg, Na, K, total-P) and of trace elements (Fe, Cu, Zn) in the plasma and erythrocytes of bulls, of experimentally induced cryptorchids (Muchsen) and of oxen of the breed Holstein-Friesian and of bulls and cryptorchids of a hybrid breed with a high portion of meat-cattle were investigated. Further the concentrations in various tissues (M. semimembranosus, M. longissimus dorsi, left and right ventricle, liver, kidney, adrenal glands, lung, spleen, testis) in bulls, cryptorchids and oxen of the breed Holstein-Friesian were analyzed. The differences of some concentrations of various elements in some tissues are discussed relative to their genesis and significance.

Animals↗
PubMed1991

[Ascorbic acid concentration in plasma, in amniotic and allantoic fluids, in the placenta and in 13 tissues of sheep fetuses and newborn lambs].

At each 8 on an average 92 (body weight 615 +/- 49 g) and 120 days (b.w. 1.8 +/- 0.40 kg) old fetuses as well as at 6 newborn lambs (b.w. 2.8 +/- 0.65 kg) the concentration of ascorbic acid in the plasma, in the amniotic- and allantois-fluid, in the fetal and maternal part of the placenta and in 13 tissues was analyzed. The highest concentration in the plasma (73 +/- 11 micrograms/ml) was determined in the newborns. The concentration in the amniotic-fluid decreased and that in the allantoic-fluid, the adrenals and the fetal part of the placenta increased in the course of growth. In the cerebrum, the cerebellum, the brain stem, the lungs, the heart, the kidneys, the M. longissimus and the M. semimembranosus the concentration diminished during the fetal growth. In the liver, the spleen and the pancreas the concentration was similar. The function of the ascorbic acid during the fetal development is discussed. The results are compared with those at human, pig and calf fetuses. In analyzing the ascorbic concentration in fetal body fluids of ungulates the high concentration of fructose as an influence-factor in the usual applied methods has to be considered.

Allantois↗
PubMed1988

Alteration of the genes for glycophorin A and B in glycophorin-A-deficient individuals.

Glycophorins A and B are homologous glycoproteins of the red cell membrane which carry the blood-group MN and Ss antigens, respectively, and are encoded by two distinct genes closely linked on chromosome 4, which are probably derived from each other by duplication during evolution. The lack of glycophorin A is associated with the rare phenotype En(a-), indicating individuals who are defective for MN antigens, as well as for the Ena antigens, also located on this glycoprotein. The En(a-) condition is heterogenous and includes two categories of variants exemplified by the Finnish and the English types referred to as En(Fin) and En(UK), respectively. By Southern blot and preliminary genomic clone analyzes we have compared the status of the genes for glycophorins A and B, as well as that of the gene encoding glycophorin C, another unrelated red cell membrane glycoprotein, in the En(a-) variants and in the En(a+) control donors. Our data indicate that the En(Fin) variant is homozygous for a complete deletion of the glycophorin A gene without any detectable abnormality of the genes encoding glycophorins B or C. In the genome of the En(UK) variant, with the presumed genotype Mk/En(UK), and where the Mk condition abolishes the expression of MN and Ss antigens, we have identified several abnormalities of the glycophorin A and B genes, but the glycophorin C gene was unaffected. Our results strongly support the view that in Mk chromosome the glycophorin A and B genes are largely deleted, whereas the En(UK) chromosome probably contains a gene fusion product encoding a hybrid glycoprotein AM-B, composed of the N-terminal portion of a blood group M-type glycophorin A and of the C-terminal portion of glycophorin B. The determination of the 5' and 3' limits of the hybrid gene and elucidation of the mechanism involved will require sequencing of the rearranged DNA of the variant and a full knowledge of the organization of the glycophorin A and B genes.

Blotting, Southern↗