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Biomedical subjects

D J Smith

Publications and source records attributed to D J Smith.

At least 217 records · Page 12Linked to original sources
PubMed1994

Effect of antibody in gingival crevicular fluid on early colonization of exposed root surfaces by mutans streptococci.

The effect of antibody to Streptococcus mutans in gingival crevicular fluid (GCF) on the recolonization of cleaned buccal root surface sites by indigenous mutans streptococci was studied. Seven subjects (mean age = 64 years) were selected from a population of 28 on the basis of the presence of appropriate sites with and without detectable immunoglobulin G (IgG) antibody in GCF to formalin-killed S. mutans and adequate levels of mutans streptococci in saliva available for root surface recolonization. Root surfaces exposed to GCF that did or did not contain antibody were then cleaned and sampled for residual plaque organisms (total cultivable flora and mutans streptococci) directly after cleaning (time 0) as well as 24 h later. One subject failed to recolonize at 24 h at any (antibody-positive or antibody-negative) experimental site. For each of the remaining 6 subjects, the mean levels of mutans streptococci (mean percentage of total flora) were lower at sites with IgG antibody to S. mutans in GCF than at antibody-negative sites in the same subject. In each of the 6 subjects, the site with the highest recolonization level was antibody-negative. Comparison based on intrasubject randomization of sites suggested diminished recolonization of mutans streptococci at sites with antibody 24 h after cleaning. The results support the idea that antibody in GCF can modify the early colonization of gingival root surface areas by potentially cariogenic plaque bacteria such as mutans streptococci.

Aged↗
PubMed1994

Adoptive transfer of cloned T helper cells ameliorates periodontal disease in nude rats.

We have previously described a T helper cell 2-type clone, A3, of rat T cells that provides help for antibody production to Actinobacillus actinomycetemcomitans in vitro and in vivo in normal (euthymic) isogeneic Rowett strain recipient rats. Adoptive transfer of this T helper cell clone to euthymic rats also protects them from periodontal bone loss induced by oral infection with A. actinomycetemcomitans. In the present study, to assess the cell requirement for protection, A3 clone T lymphocytes (10(6)) or naive lymph node (6 x 10(4)) T cells, or A3 plus naive lymph node T cells (6 x 10(4)) were adoptively transferred to groups (n = 7-9) of 30-day-old Rowett athymic nude (rnu/rnu) rats. All recipients were also immunized (intraperitoneally) with 10(7) killed A. actinomycetemcomitans on the day of T cell transfer and orally infected with these bacteria on each of the next 5 days. Recipients of the combined A3+lymph node T cell transfer showed significantly increased serum immunoglobulin G (IgG) and IgM antibody to A. actinomycetemcomitans and in vitro proliferation of spleen lymphocytes to A. actinomycetemcomitans as antigen compared with nude animals receiving lymph node T cells only. Although other possibilities are discussed, we inferred that these differences might be due to successful population of the congenitally athymic rats by A3 clone cells given with a small number of normal autologous naive lymph node T cells. The result of this co-transfer of naive T cells with the A3 clone cells seemed to be greatly increased antibody production and protection from periodontal bone loss.

Aggregatibacter actinomycetemcomitans↗
PubMed1994

Ectopic human chorionic gonadotrophin (HCG) production: is the detection by serum analysis of HCG of clinical relevance in transitional cell carcinoma of the bladder?

OBJECTIVE: To assess the potential value of ectopic beta-human chorionic gonadotrophin (beta HCG) measurement in the clinical management of transitional cell carcinoma (TCC). PATIENTS AND METHODS: A prospective serological study of 163 consecutive patients undergoing cystoscopy as new or review cases was performed to assess any correlation between beta HCG production and histological grading or stage. RESULTS: Ten per cent of patients with TCC had a raised beta HCG level but there was no correlation with tumour differentiation, staging or prognosis. CONCLUSIONS: beta HCG has no role as a tumour marker for TCC and therefore appears unlikely to play a part in the clinical management or treatment of urothelial tumours.

Biomarkers, Tumor↗
PubMed1994

Immunological characteristics of a synthetic peptide associated with a catalytic domain of mutans streptococcal glucosyltransferase.

The immunogenicity of a multiple antigenic peptide construct consisting of four copies of the synthetic 21-mer peptide DANFDSIRVDAVDNVDADLLQ was measured. The composition of this peptide was derived from a sequence in the N-terminal region of mutans streptococcal glucosyltransferases (GTFs) containing an aspartic acid implicated in catalysis. The peptide (CAT) construct was synthesized as a tetramer on a lysine backbone and subcutaneously injected into Sprague-Dawley rats for polyclonal antibody formation or intraperitoneally injected into BALB/c mice, and then spleen cell fused with Sp2/0Ag14 murine myeloma cells for monoclonal antibody formation. The resulting rat antisera and mouse monoclonal antibodies reacted with CAT and with native GTF isozymes from Streptococcus sobrinus and Streptococcus mutans (in enzyme-linked immunosorbent assay and Western blot [immunoblot] analyses). Functional inhibition of the water-insoluble glucan synthetic activity of S. sobrinus GTF-I was demonstrated with an immunoglobulin M anti-CAT monoclonal antibody (> 80% inhibited) and with rat sera (approximately 17% inhibited). The monoclonal antibody preparation also modestly inhibited the water-soluble glucan synthetic activity of an S. mutans GTF mixture. These results suggest that the CAT peptide contains B-cell epitopes that are similar to those of intact mutans streptococcal GTFs and has the potential to elicit antibody that can inhibit GTF function. Thus, sequences within this peptide construct may have value for inclusion in a synthetic dental caries vaccine.

Amino Acid Sequence↗
PubMed1994

Purification and antigenicity of a novel glucan-binding protein of Streptococcus mutans.

A novel glucan-binding protein (GBP) having an apparent molecular mass of 59 kDa (GBP59) has been purified from Streptococcus mutans SJ by a combination of affinity chromatography on alpha-1,6-linked glucan, gel filtration chromatography, and ion-exchange chromatography. GBP59 was distinct from the quantitatively predominant S. mutans GBP (GBP74) on the basis of size, elution position in a salt gradient, and antigenicity. Rat antisera to purified GBP59 and GBP74 did not cross-react. GBP59 is apparently immunogenic in humans, since immunoglobulin A (IgA) antibody in 20 of 24 adult parotid saliva samples was shown to react with GBP59 in an enzyme-linked immunosorbent assay. The glucan-binding activity of GBP59 was confirmed by anti-GBP59 immunogold labelling of Sephadex G-50 that had been preincubated with S. mutans culture supernatant. GBP59 could be detected in culture supernatants of all laboratory strains of S. mutans (e.g., Ingbritt), as well as all strains of S. mutans that had been recently isolated from young children. GBP59 was often the only component in protease inhibitor-containing 4-h S. mutans culture supernatants that reacted with human parotid salivary IgA antibody in Western blot (immunoblot) analyses. These studies suggest that GBP59 is a structurally and antigenically distinct S. mutans GBP that can elicit significant levels of salivary IgA antibody in humans.

Animals↗
PubMed1994

Hyphal tip extension in Aspergillus nidulans requires the manA gene, which encodes phosphomannose isomerase.

A strain of Aspergillus nidulans carrying a temperature-sensitive mutation in the manA gene produces cell walls depleted of D-mannose and forms hyphal tip balloons at the restrictive temperature (B.P. Valentine and B.W. Bainbridge, J. Gen. Microbiol. 109:155-168, 1978). We have isolated and characterized the manA gene and physically located it between 3.5 and 5.5 kb centromere distal of the riboB locus on chromosome VIII. The manA gene contains four introns and encodes a 50.6-kDa protein which has significant sequence identity to type I phosphomannose isomerase proteins from other eukaryotes. We have constructed by integrative transformation a null mutation in the manA gene which can only be maintained in a heterokaryotic strain with wild-type manA+ nuclei. Thus, a manA null mutation is lethal in A. nidulans. The phenotype of the mutation was analyzed in germinating conidia. Such conidia are able to commence germination but swell abnormally, sometimes producing a misshapen germ tube, before growth ceases. The reason for the lethality is probably the lack of synthesis of mannose-containing cell wall polymers that must be required for normal cell wall development in growing hyphae.

Amino Acid Sequence↗
PubMed1994

The effects of learning strategy instruction on the completion of job applications by students with learning disabilities.

The purpose of this study was to assess the effects of learning strategy instruction on the completion of job applications by students identified as learning disabled. Thirty-three students (average age 15 years 6 months) were randomly assigned by grade and gender to one of two experimental conditions: learning strategy instruction or traditional instruction. The result was 16 students (10 boys and 6 girls) being placed under the learning strategy instruction condition and 17 students (10 boys and 7 girls) being placed under the traditional instruction condition. Results indicated that in addition to statistically significant lower numbers of information omissions and information location errors, holistic ratings of the overall neatness of the job applications were significantly higher for those students under the learning strategy instruction condition. In addition to these positive changes in the performance measures, social validity data suggest that students under the learning strategy condition would be more likely to receive an invitation for a job interview. The findings and future research needs are discussed.

Adolescent↗
PubMed1994

Growth characteristics of rats receiving ractopamine hydrochloride and the metabolic disposition of ractopamine hydrochloride after oral or intraperitoneal administration.

Objectives of this study were 1) to measure the effect of oral or i.p. administration of ractopamine HCl on growth and feed utilization in rats, 2) to determine the total absorption of [14C]ractopamine HCl after oral administration, and 3) to determine the disposition of radioactivity and the urinary elimination of unchanged [14C]ractopamine in rats after oral or i.p. administration of [14C]ractopamine. Twenty-seven female Sprague-Dawley rats (164.6 +/- 5.7 g) were randomly assigned to control (CONT), oral (ORAL), and i.p. (IP) treatments. Control and ORAL rats were implanted i.p with sham pumps, and IP rats were implanted i.p. with osmotic pumps primed to deliver 312 micrograms of ractopamine HCl per 24 h. Control and IP rats received no dietary ractopamine, but ORAL rats received 20 mg of ractopamine HCl/kg of diet. The IP rats had greater cumulative net weight gains and ADG on d 2, 6, 8, 10, and 12 than CONT rats. The ADFI was greater for ORAL rats on d 2 and 4 than for CONT rats, and the gain:feed ratio was greater on d 2, 6, 8, 10, and 12 for IP rats than for CONT rats. Net weight gain, ADG, and gain:feed ratio did not differ between ORAL and CONT rats. Absorption of radioactivity administered orally as [14C]ractopamine (2.9 mg) was 87.9% during a 24-h experimental period; biliary, urinary, and fecal excretion of radioactivity was 58.5%, 28.7%, and 1.4% of that administered, respectively. Urine from rats dosed orally with [14C]ractopamine contained 1.9% of the radioactivity as the parent compound, and urine from rats dosed i.p. contained 22.6% of the radioactivity as parent ractopamine. Ractopamine HCl increased weight gain and efficiency of feed utilization when administered i.p. to rats, but not when administered orally. The ineffectiveness of oral ractopamine for stimulating the growth of rats was probably due to extensive presystemic metabolism of ractopamine.

Absorption↗
PubMed1994

Phagocytosis of a fluorescently labeled perflubron emulsion by a human monocyte cell line.

We hypothesized that fluorocarbon-based lipid emulsions are phagocytosed by monocytes and that many of the in vivo side effects related to the infusion of these particulate emulsions are due to release of cytokines by these monocytes. To clarify whether these emulsions are actually phagocytosed we attempted to measure by flow cytometry the apparent uptake of a fluorescently labeled high-concentration (90%, w/v) perflubron (perfluorooctyl bromide [PFOB]) emulsion by a differentiated human monocyte cell line. A fluorescent chromophore (Zynaxis Cell Science) was used to label the egg yolk phospholipid in a perflubron emulsion. This phospholipid label was used to track the perflubron emulsion during overnight incubation with the human monocyte (THP-1) cell line which had been differentiated, by exposure to PMA, into macrophage-like cells. Our results indicate that after 24 hours of incubation with the labeled perflubron emulsion, 64.9% (+/- 11.0) of differentiated THP-1 cells had cell-associated emulsion (ingested and/or membrane bound) whereas 24.4 (+/- 6.8%) of the control cells had cell-associated emulsion. We speculate that this technique may be a useful method to track the intravascular persistence and extravascular distribution of such emulsions, and that the degree of uptake of the emulsion by macrophages in this assay may correlate with its in vivo half life.

Cell Line↗
PubMed1994

Acute skin injury releases neutrophil chemoattractants.

BACKGROUND: Progressive or ongoing skin necrosis after traumatic injury is well known. Experimental evidence has associated these events with neutrophil activation and secondary oxidant injury. To determine the mechanism by which neutrophils migrate to a site of injury, cytokine release from injured skin was measured. METHODS: Twenty-five skin biopsy specimens of acute partial thickness skin injuries were compared with uninjured skin of the same patient. Conditioned medium from explanted skin was assayed for tumor necrosis factor (TNF), interleukin-6 (IL-6), and IL-8. RESULTS: Acute skin injury resulted in a significant release of IL-8 but not IL-6 or TNF. In eight patients gradient cytokine release was found; IL-8 levels for partial thickness burn were 26.4 ng/ml, for unburned skin adjacent to the burn were 2.1 ng/ml, and for distal normal skin were 0.2 ng/ml. CONCLUSIONS: IL-8 is released from acutely injured skin; IL-6 and TNF are not. This selective release suggests a mechanism whereby neutrophils are recruited into injured tissue. These neutrophils might then induce further injury, increasing the extent of posttraumatic tissue loss.

Acute Disease↗
PubMed1993

The hemoglobins of the bullfrog, Rana catesbeiana. The cDNA-derived amino acid sequences of the alpha chains of adult hemoglobins B and C: their roles in deoxygenation-induced aggregation.

The adult bullfrog (Rana catesbeiana) has two major tetrameric hemoglobins, B and C, which share a common beta chain but have different alpha chains. Components B and C associate upon deoxygenation to form a complex of the form BC2, a trimer of tetramers that depends on contacts between the alpha B and alpha C chains. Nucleotide sequences of cDNA transcripts for these chains have been determined. Transcripts were identified by analysis of the amino acid compositions of the tryptic peptides of the components and by partial amino acid sequencing. These results, together with the amino acid sequence of the beta chain (Tam, L.-T., Gray, G. P., and Riggs, A. F. (1986) J. Biol. Chem. 261, 8290-8294), permit an analysis of the structures of the alpha 2 beta 2 tetramers of hemoglobins B and C. Molecular modeling suggests possible residues at the alpha B-alpha C interfaces in the BC2 trimer and additional alpha C-alpha C contacts that would form a closed ring of six alpha chain subunits that would further stabilize the BC2 trimer. Phylogenetic analysis of the alpha B sequence suggests that it may be a "tadpole" chain, the temporal expression of which has shifted from larva to adult.

Amino Acid Sequence↗
PubMed1993

The human cathepsin D-encoding gene is transcribed from an estrogen-regulated and a constitutive start point.

The 5' flanking sequences, exon 1 and part of intron 1 of the human cathepsin D (CTD)-encoding gene (CTD) have been cloned and sequenced. RNase protection experiments identified two major transcription start points (tsp) located 14 and 63 nucleotides upstream of the start codon. The proximal -14, but not the distal -63 tsp has upstream near-concensus TATAAA and CCAAT sequences. Estrogens increase transcription from the -14 tsp, but not the -63 tsp and CTD is therefore unique among estrogen-regulated genes in having estrogen-regulated and constitutive transcription. Sequencing approximately 800 bp upstream and 600 bp downstream of the tsp failed to identify a consensus 13-bp palindromic estrogen-response element (ERE); however, four half-palindrome GGTCA motifs were located within 340 bp upstream of the -14 bp tsp. Thus, estrogen regulation of CTD may not be mediated by a consensus ERE.

Base Sequence↗