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Biomedical subjects

G N Smith

Publications and source records attributed to G N Smith.

At least 127 records · Page 7Linked to original sources
PubMed1983

Histochemical identification of sulfation position in chondroitin sulfate in various cartilages.

The ability of chondrocytes to synthesize chondroitin-4-sulfate (C4S) as opposed to chondroitin-6-sulfate (C6S) is a phylogenetically related phenomenon seen among adult higher vertebrates and developmentally during the embryogenesis of these vertebrates. While the embryonic cartilage may be initially a C6S matrix, C4S synthesis is seen to develop with time. We have histochemically localized these differences in sulfation with the cationic carbocyanine dye, Stains-all, in a spectrum of cartilages that vary in the sulfation position of their chondroitin sulfate. Cartilages from the rat and rabbit that are predominantly C4S stained magenta at pH 4.3, while the C6S-rich cartilage matrices from the regenerating rabbit ear and lamprey cranium stained blue. Embryonic chicken cartilages develop a gradient of magenta matrix with age, with increased concentration toward the articular surface. Both magenta and blue matrices were absent after pretreatment with chondroitinase ABC but were present after Streptomyces hyaluronidase digestion. The magenta staining was a property of the cartilage matrix as a whole, since isolated C4S and C6S stained blue. The differential staining was seen at pH 4.3, but not at pH 8.8, suggesting an interaction between the chondroitin sulfate and the adjacent tissue proteins.

Alcian Blue↗
PubMed1983

Clinical evaluation of periodontal ligament anesthesia using a pressure syringe.

Conventional local anesthesia techniques are frequently unsuccessful, particularly for endodontic procedures. Supplementary injections are often necessary; the periodontal ligament injection is useful for this purpose. This study examined the effectiveness of injecting into the periodontal ligament with a pistol-type pressure syringe as a supplemental technique in patients who did not have adequate anesthesia for endodontic therapy. Sixty patients received the supplemental injections and 20 patients were reinjected when the first PDL injection failed. Data were obtained by questionnaire. Percentages were computed and comparisons made by X2 analysis. The conclusions about attaining anesthesia included: --Needle size was not important; overall, 25- and 30-gauge needles were equivalent. --Injecting under strong back-pressure was important; the greatest frequency of success was attained when injecting under pressure. Lack of back-pressure on both mesial and distal surfaces resulted in a significantly lower incidence of anesthesia. Proper positioning of the needle and maintaining this position, to force the anesthetic deep into the periodontium, is apparently an effective way to generate the needed back-pressure. --Strong back-pressure could usually be attained on either or both surfaces. --Reinjection was frequently successful if the first periodontal ligament injection failed. --Overall frequency of success in attaining anesthesia with the pistol-type pressure syringe was 83%. This was determined by including the instances in which reinjection was necessary. --Comparing the results of this study with a previous similar study, the pressure syringe were equally effective for supplementary anesthesia.

Anesthesia, Dental↗
PubMed1982

Collagens from the skin and cartilage of the larval salamander Ambystoma tigrinum.

The major collagens of larval salamander (Ambystoma tigrinum) skin and cartilage were purified and characterized by CM-cellulose chromatography and amino acid analysis of the component alpha chains. The collagens are similar to type I (skin) and type II (cartilage) collagens of birds and mammals. The type I molecule has the chain composition (alpha 1)2 alpha 2, and the type II molecule is an (alpha 1)3 molecule. Both collagens have lower levels of proline hydroxylation than the collagens isolated from homoiotherms, and generally higher serine contents. The type II collagen molecule has about half of its lysine residues hydroxylated, as in cartilage collagens of other species. Cyanogen bromide digestion of the component alpha chains followed by CM-cellulose chromatography or SDS gel electrophoresis of the peptides confirms that each chain is a different gene product and allows identification of the collagens in this species. Similar collagens were isolated from newt (Notophthalmus viridescens) tissues by pepsin extraction and fractional salt precipitation. These data will allow more effective utilization of the regeneration salamander limb for studies of collagen metabolism during regeneration.

Ambystoma↗
PubMed1982

A simple method for the isolation of vitamin D metabolites from plasma extracts.

A simple method has been developed using 'SEP-PAK' disposable silica cartridges to separate the major endogenous vitamin D metabolites, namely vitamin D3, 25-hydroxy vitamin D3 (25OHD3), 1,25 dihydroxy vitamin D3 (1.25 (OH)2D3) and 24,25 dihydroxyvitamin D3 (24,25 (OH) 2D3). After extraction of plasma in isopropanol-toluene (25:75) the dried extract is reconstituted in hexane; this is applied to a SEP-PAK column, and stepwise elution carried out under gravity with 0.1 divided by isopropanol in hexane (neutral lipids), 1% isopropanol in hexane (D3), 3 divided by isopropanol in hexane (25OHD3), 3.125 divided by ethanol in dichloromethane (24,25 (OH) 2D3) and 50 divided ethanol in toluene (1, 25(OH) 2D3). Complete separation of these D3 metabolites is achieved by this process and up to 40 samples can be handled at one time. If combined with a suitable ligand binding assay, the system appears to be suitable for preparation of samples prior to the routine assay of vitamin D metabolites.

24,25-Dihydroxyvitamin D 3↗
PubMed1982

Epidermal cell migration on collagen and collagen-derived peptides.

Nucleopore filters coated with various genetic types of collagen and certain collagen-derived peptides were implanted under one margin of a skin wound on adult Notophthalmus viridescens (newt) hind limbs. In contrast to their behaviour on untreated filters, epidermal cells migrated readily and to equal degrees on human type I, newt type I, bovine type II, and bovine type IV collagen. Denaturation had no effect on the ability of collagen to support migration and all three cyanogen bromide peptides tested (alpha 1(I)CB3, 7 and 8) were able to support more migration than that seen on untreated filters. Glutaraldehyde-linked collagen gels supported migration but bovine serum albumin gels did not. These results show that there is no species or collagen-type specificity shown by newt epidermal cells as they migrate over collagen-coated substrates. They also demonstrate that the tertiary structure of the collagen molecule is unimportant in its ability to bind to newt epidermal cells, and that the alpha 1(I) chain has at least three, and probably many epidermal binding sites. Finally, they indicate that the improved migration on collagen is not a non-specific response to protein on the substrate.

Animals↗
PubMed1982

The effect of cyclosporin A on the primary immune response to allogeneic red cells in rabbits.

Cyclosporin A (CSA) has been used in an attempt to suppress the primary immune response of HgA(A)-negative rabbits to A-positive red cells. The immune response was assessed by measuring the survival of a small intravenous (i.v.) dose of 51Cr-labelled A-positive cells and by testing the serum of the immunized rabbits for anti-A. In one experiment, eight A-negative rabbits were given a first i.v. injection of A-positive red cells, and CSA (25 mg/kg/day) in olive oil was given by mouth for 17-34 days. There was no evidence of impaired alloimmunization compared with the responses in control animals treated with olive oil alone. In a second experiment, eight A-negative rabbits were given a first injection of A-positive muscularly (i.m.), and CSA (25 mg/kg/day) in miglyol was given by im.m. injection for 10 days. Six of these rabbits were rendered unresponsive, and the remaining two, who showed impaired survival of the monitoring red cells, produced only low anit-A titres. Seven out of eight controls given i.m. miglyol without CSA responded with good anti-A production. Rabbits that were unresponsive to A-positive red cells responded normally to sheep red blood cells 15 weeks after CSA treatment. Higher serum levels of CSA were found following i.m. administration of the drug but treatment by this route as associated with severe toxicity in some rabbits.

Animals↗
PubMed1980

Premolar enucleation and autogenous transplantation.

Tooth transplantation by autograft and orthodontic treatment can be used to correct occlusal disharmony and avoid fixed partial dentures. Premolars are used in this case to accomplish almost normal dentition.

Anodontia↗
PubMed1979

Lack of effect of immunotherapy with BCG and Corynebacterium parvum on hepatic drug hydroxylation in man.

Serial serum diphenylhydantoin and urinary 5-(p-hydroxphenyl)-5-phenylhydantoin concentrations were determined in 8 patients with malignant disease and 4 healthy volunteers on 2 separate occasions after an oral dose of diphenylhydantoin (500 mg). No significant difference was observed between metabolism before and 10 days after immunization with BCG or Corynebacterium parvum. Volunteers without intervening immunization similarly showed no difference.

Adenocarcinoma↗
PubMed1977

Synthesis of two collagen types by embryonic chick corneal epithelium in vitro.

To better understand the mechanisms involved in matrix development, we have analyzed the collagen synthesized by embryonic corneal epithelium, the tissue known to produce the collagenous component of the primary corneal stroma. Isolated epithelia were cultured in vitro in medium containing [oH]proline and the newly synthesized, labeled collagen was extracted, fractionally salt precipitated, and analyzed by carboxymethyl-cellulose chromatography and peptide mapping after cleavage with cyanogen bromide. The data show that the cornela epithelium produces at least two different types of collagen, one similar, if not identical, to the type I molecule of skin, and a second similar, if not identical, to the type II molecule of cartilage. Type II, heretofore, had been thought to be characteristic of cartilage extracellular matrix.

Animals↗