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Biomedical subjects

A Pierce

Publications and source records attributed to A Pierce.

At least 55 records · Page 3Linked to original sources
PubMed1993

Transcriptional induction of beta-galactoside alpha-2,6-sialyltransferase in rat fibroblast by dexamethasone.

The beta-galactoside alpha-2,6-sialyltransferase activity of Fisher rat fibroblasts is enhanced by dexamethasone while the activity of the beta-galactoside alpha-2,3-sialyltransferase remains unchanged. This glucocorticoid-dependent activation can be inhibited by the antagonist RU 38,486 and results from an elevated transcription rate of the 4.7-kb mRNA previously characterized in rat fibroblasts, distinct from the 4.3-kb liver-restricted mRNA. As shown by the binding of radiolabelled Sambucus nigra agglutinin, this activation leads to an increase of NeuNAc(alpha 2-6)Gal sequences on glycoproteins isolated from the dexamethasone-treated cells.

Animals↗
PubMed1992

Molecular cloning of the major cell surface heparan sulfate proteoglycan from rat liver.

We have used an antiserum raised against a purified heparan sulfate proteoglycan (HSPG) preparation isolated from rat liver to screen a lambda gt11 expression library and have obtained overlapping cDNA clones that contain the full-length coding sequence of an HSPG core protein capable of spanning the plasma membrane. The open reading frame of the rat cDNA encodes a protein of 211 amino acids. The predicted protein sequence (23 kDa) has a high degree of homology with the published partial sequence of the human lung fibroblast HSPG, fibroglycan. The deduced protein sequence contains a 24-amino acid transmembrane domain and a 33-amino acid cytoplasmic domain, both of which are identical with the corresponding regions of human fibroglycan and are highly homologous to the human, hamster, and mouse epithelial HSPG, syndecan. The putative ectodomain, which has 85% homology to fibroglycan, contains three possible glycosaminoglycan attachment sites that may be occupied by heparan sulfate chains. The major 49-kDa core protein in the liver HSPG preparation was found to be reactive to an antibody that specifically recognizes the cytoplasmic domain of fibroglycan. We have used the full-length cDNA clone to analyze the expression of this transmembrane core protein gene in whole tissues and several epithelial and fibroblastoid cell lines. It hybridizes to three mRNA species in all cell and tissue types examined, but in liver, isolated hepatocytes, and kidney, an additional 0.8-kilobase mRNA was detected. The three common messages arise from differential use of alternative polyadenylation sites, whereas the fourth tissue-restricted RNA species represents a related gene transcript. The rat equivalent of human fibroglycan therefore appears to be the major transmembrane proteoglycan in liver, and its widespread expression in many diverse tissues and cells suggests that it plays an important role in cellular interactions.

Amino Acid Sequence↗
PubMed1991

Molecular cloning and sequence analysis of bovine lactotransferrin.

The screening of a bovine submaxillary gland cDNA library yielded 25 clones coding for bovine lactotransferrin. The nucleotide sequence of the longest insert contained a protein-coding region of 2115 nucleotides and a 3' non-coding region of 194 nucleotides followed by a poly(A) tract of about 55 nucleotides. The predicted peptide sequence included a 16-amino-acid signal sequence upstream of the first amino acid of the native protein. The identity of the clone was confirmed by matching the amino acid sequence predicted from the cDNA with the N-terminal and tryptic peptide sequences derived from purified bovine milk lactotransferrin, and also by similarity with human and murine lactotransferrins. The cDNA described corresponds to a 705-amino-acid-long preprotein that lacks the start methionine. The sequence of the secreted protein is 689 amino acids long and contains five potential glycosylation sites. Bovine lactotransferrin is 69% and 64% identical to human and murine lactotransferrins, respectively.

Amino Acid Sequence↗
PubMed1991

Surface resorption following two forms of rapid maxillary expansion.

Rapid maxillary expansion (RME) is a useful orthodontic technique for correction of posterior cross-bite of skeletal origin. The aim of the present study was to compare the frequency and nature of root resorption in premolars subjected to RME by means of either a tissue-borne, fixed split acrylic (Haas) palatal expansion applicance, or an all-wire framework appliance. Another factor examined was the relationship between the pattern of resorption and the duration of the retention period. RME was performed on five patients using the fixed split acrylic appliance and on four patients with the all-wire framework appliance. Following the transverse expansion, two upper and two lower premolars were extracted and processed for histological examination. Root resorption was found mainly on the buccal surfaces of all maxillary premolars. The resorption lacunae covered more of the root surface in premolars treated with an all-wire framework appliance compared to premolars treated with the acrylic expansion plate. The largest resorption areas were found on teeth extracted shortly after the expansion period and the smallest on premolars retained for a relatively longer period. Mandibular premolars showed neither buccal nor lingual resorptions. It was concluded that maximum anchorage of the expansion device, using the tissue-borne acrylic appliance, seems preferable in order to minimize the incidence of buccal surface root resorption. A longer post-treatment observation time is needed in order to draw more specific conclusions regarding the healing process of the damaged root surface.

Acrylic Resins↗
PubMed1989

Development of elastic fibres in the upper urinary tract.

The development of elastic fibres in the upper urinary tract was studied in 31 fetuses ranging in ovulatory age from 10 to 24 weeks using special staining techniques for elastic fibres. The number, orientation and distribution of elastic fibres are described and correlated with age, ureteric level, and fetal weight. Significantly, before 10 weeks, elastic fibres were few in number, poorly developed, and randomly arranged. After 12 weeks, these fibres became more numerous at each level of the urinary tract, and were seen to develop specific orientation. The findings are described and potential clinical implications are discussed.

Elastic Tissue↗
PubMed1989

Pathophysiological and therapeutic aspects of dentoalveolar resorption.

Both physiological and pathological forms of bone and tooth resorption are seen in the dentoalveolar complex, and much of the non-restorative component of a clinician's work is occupied by problems related to loss of bone or dentine. Bone resorption is also a feature of many systemic diseases, some of which can affect the alveolar bone. The aim of this report is to summarize some recent work in which the dentoalveolar complex has been used as a model system to study physiological, pathological and therapeutic aspects of resorption of bone and dentine.

Bone Resorption↗
PubMed1989

Chemical toxicology for the coroner.

Toxicology results from all 302 coroners' cases referred to the supraregional unit at Beaumont Hospital over the one year period December 1987 to November 1988 are detailed. Clinical details were provided in 69.5% and formed the basis for the formation of four groups; road traffic accidents, suicides, possible suicides and possible carbon monoxide poisonings. All tests reported were instigated by the referring pathologist on behalf of the coroner. Alcohol was measured in all except 11 patients and a positive result was found in 44%. Drug screens were performed in 68.5% of cases with a positive finding in 30%. At least one positive result was found in 61.9% of the total. In the 60.4% of 53 road accident victims where alcohol was found, the median value was 117 mg/dl. COHb was measured in 23 cases and the median saturation was 45%. There were 12 suicides and agents found included paraquat, CO, cyanide, pancuronium bromide, and amitriptyline. Alcohol levels greater than 120 mg/dl were present in seven. In the 22 cases of suspected suicide, 77.3% were positive for drugs and more than one substance was found in 45.4%.

Accidents, Traffic↗
PubMed1988

Spreading of dentinoclasts on various substrata in vitro.

An in vitro system for isolated dentinoclasts is described in which clastic cells which are not contemporaneously engaged in resorption are gently rinsed from the surface of actively resorbing root dentin. Dentinoclasts were cultured on a variety of hard tissue constituents in order to investigate the effects of substratum composition on the expression of resorbing structures by these cells, and examined with scanning electron microscopy. Results revealed that dentinoclasts express both ruffled borders and clear zones only when cultured on coverslips coated with both collagen and hydroxyapatite. Hydroxyapatite alone induced only the formation of a clear zone. Failure to express either clear zones or ruffled borders by cells cultured on collagen-coated coverslips was interpreted to reveal that collagen itself is not capable of, but requires the mineral component of hard tissue for, producing morphologic resorbing structures in clastic cells.

Albumins↗
PubMed1988

Coated pits and vesicles in the osteoclast.

The osteoclast is a cell with a phagocytic ability not dissimilar to the macrophage. Nevertheless, the mechanisms by which it resorbs bone are poorly understood. The aim of this study was to examine the distribution of coated membrane structures in the osteoclast in order to gain further information about endocytosis in this cell. Osteoclasts around the developing tooth germs of young rats were examined using transmission electron microscopy, and immunocytochemistry. Results showed that previously described coated membrane structures within the ruffled border do not appear to be associated with coated pits or vesicles. Coated pits were, however, evident on the dorsal and lateral surfaces of the cell, particularly opposite the clear zone areas. Immunogold staining for clathrin confirmed that coated pits and vesicles are absent within both the clear zone and ruffled border areas, but present on the lateral and dorsal surfaces of the actively resorbing cell. It is suggested that clathrin-associated receptor-mediated endocytosis occurs along the lateral and dorsal surfaces of the osteoclast for the uptake of nutrients and macromolecules, while endocytosis of bone mineral by the ruffled border is mediated by a non-clathrin associated coated membrane structure.

Animals↗
PubMed1987

The effect of an antibiotic/corticosteroid paste on inflammatory root resorption in vivo.

Progressive external inflammatory root resorption, a result of persistent inflammation within the periodontal membrane, will cause eventual destruction of the tooth root if the inflammation is not eradicated. This study examined the effects of an antibiotic/corticosteroid paste on experimental inflammatory resorption induced in monkeys in vivo. Histologic evaluation of results with the use of a morphometric technique revealed that the paste eliminated inflammatory root resorption and had no damaging effects upon the periodontal membrane. It was concluded that this antibiotic/corticosteroid combination is an effective medication for use in the treatment of progressive root resorption in traumatically injured teeth.

Animals↗
PubMed1987

Surgicel: macrophage processing of the fibrous component.

Previous reports have demonstrated that Surgicel, a local haemostatic agent, is absorbed from implantation sites. In an earlier study, it was shown that the material consists of a uronic acid component and a fibrous residue. A chemically quantified loss of the uronic acid component within 18 h of implantation was demonstrated. The aim of the present study was to examine the fate of the fibrous residue in rat tissues, using both light and electron microscopy. Results indicated that this fibrous component is phagocytosed by macrophages at the site of implantation. A model for the clearance of Surgicel from tissue implantation sites is presented.

Animals↗
PubMed1987

Resorbing potential of different connective tissue types.

Pieces of dentin were implanted into five different connective tissues in rats and examined with scanning electron microscopy after observation periods of up to 2 weeks. Dentin-oclast-like cells, apparently involved in resorption of the implants, were only seen associated with periosteum and periodontal membrane. These findings indicate that the resorbing potential of connective tissues is related to their ability to induce bone formation.

Animals↗
PubMed1986

Induction of a protective immune IgE response in rats by injection of defined antigens of schistosomulum-released products: immunochemical properties of the target antigens.

Brown Norway rats were injected without adjuvant with the soluble products liberated in a 16-hour culture by schistosomula (schistosomula-released products, SRP-A). A strong cytotoxic and protective IgE response was elicited, mainly directed against 22- and 26-kilodalton (kDa) SRP-A molecules. In the present study, we have attempted to characterize further those molecules. Metaperiodate denaturing treatment of the SRP-A glycans before injection into rats did not modify the immunogenicity of the SRP-A antigens. Results obtained by lectin affinity suggested that the 22- and 26-kDa molecules were glycoconjugates binding to ConA. Preparative sodium dodecylsulfate electrophoresis has allowed the separation of enriched fractions of 22- and 26-kDa molecules which have been injected separately into rats. The corresponding sera were tested in antibody-dependent cell cytotoxicity and displayed a significant cytotoxic IgE response (65 and 53%, respectively) towards the larvae. These results lend further support to the view that the 22- and 26-kDa antigens are the major targets of the protective IgE response and thus appear as potentially protective antigens.

Animals↗