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Biomedical subjects

D MacKenzie

Publications and source records attributed to D MacKenzie.

At least 55 records · Page 3Linked to original sources
PubMed1990

Bacteraemia following incision and drainage of dento-alveolar abscesses.

Twenty-five patients undergoing routine incision and drainage of dento-alveolar abscesses were screened for bacteraemia during the procedure. In 13 patients, the abscesses were aspirated with a needle prior to incision and drainage, while needle aspiration was omitted in the remaining 12. A blood sample was taken from all individuals immediately before the surgical procedures and at one-minute intervals for a period of 5 minutes after surgery. Needle aspiration of pus resulted in a significant reduction (P less than 0.05) in the bacteraemic episodes (0 out of 13) during subsequent surgery as compared with incision and drainage, without aspiration (3 out of 12). Bacteraemia appeared to be transient, although in one case it was detected at 5 minutes. It is concluded that bacteraemic episodes occur during incision and drainage of dento-alveolar abscesses and this may be reduced by aspiration of the abscess contents prior to incision and drainage. In addition, the aspirates could serve as excellent microbiological samples, uncontaminated with salivary flora. The need for antibiotic cover in at risk patients, however, needs to be established by further studies.

Bacteria↗
PubMed1990

The microbiology of periapical granulomas.

Of the 16 periapical granulomas studied, 14 (88%) yielded a positive growth when homogenized and cultured. The concentration of colony-forming units per milliliter of the suspension ranged from 10(1.3) to 10(4.0) (mean 10(2.2)). A total of 47 isolates comprising 26 (55%) facultative anaerobes and 21 (45%) strict anaerobes were obtained. The organisms most commonly cultured were Veillonella species (15%), Streptococcus milleri (11%), Streptococcus sanguis (11%), Actinomyces naeslundii (11%), Propionibacterium acnes (11%), and Bacteroides species (10%). Most of the organisms (96%) were sensitive to either amoxicillin, clindamycin, or tetracycline, whereas only 45% were sensitive to metronidazole.

Adolescent↗
PubMed1989

Increased sensitivity for rapid detection of cytomegalovirus by shell vial centrifugation assay using mink lung cell cultures.

A comparative study was made of various human and non-human cell cultures to determine their sensitivity for cytomegalovirus (CMV) as detected by the production of CMV early antigen using the shell vial centrifugation assay. Mink lung cell cultures, frequently used for detection of herpes simplex virus in clinical specimens, were found to be significantly more sensitive to infection by CMV than other cell cultures tested. Using the shell vial centrifugation assay, the mink lung cell cultures were more sensitive than human diploid fibroblasts for the detection of the Davis strain of human CMV and CMV from clinical specimens.

Animals↗
PubMed1989

Systemic metronidazole in the treatment of periodontitis.

The present study evaluated the effect of systemic metronidazole on advanced periodontitis in 10 patients with inadequate oral hygiene. Clinical and microbiological observations were made at a total of 173 bleeding pockets of 5 mm depth or more. The clinical observations comprised plaque index scores, dichotomous measurements of gingival redness and suppuration, pocket depths and attachment levels. The microbiological variables investigated were the % spirochaetes, % black-pigmented Bacteroides species, % facultative streptococci and presence of absence of Bacteroides gingivalis. At baseline, after clinical measurements and microbiological samples had been taken, each patient received a thorough scaling and root planing. After 3 months, the clinical measurements and microbiological sampling were repeated and a 5-day course of metronidazole was administered while one side of the mouth was scaled and root planed. After a further 3 months, the final measurements and samples were taken. In comparing pre- and post-treatment data, the following significant differences were observed: for debridement alone, a reduction in mean % spirochaetes from 11.5% to 4.9% and an increase in mean % streptococci from 4.7% to 8.8%; for metronidazole alone, a 0.3 mm gain in mean attachment level, a 0.4 mm reduction in mean pocket depth and a reduction in the frequency of suppurating sites from 32% to 16%; for debridement plus metronidazole, a 0.2 mm gain in mean attachment level, a 0.5 mm reduction in mean pocket depth and a reduction in mean % spirochaetes from 5.6% to 2.5%. Thus systemic metronidazole, either alone or accompanied by debridement, produced a modest clinical improvement after debridement alone had failed.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1987

Failure of post-bacteraemia delayed antibiotic prophylaxis of experimental rabbit endocarditis.

Twenty-one rabbits had a cannula placed in the left ventricle and 48 h later 1 ml of a culture of Streptococcus sanguis NCTC 7864 was injected into an ear vein. Six hours later, 400 mg/kg of amoxycillin was administered intramuscularly to 17 animals, the others acting as non-antibiotic treated controls. Two of the 17 rabbits died during the experimental period, and the cannula was incorrectly placed in another two. Five of the remaining 13 animals developed endocarditis. All controls developed endocarditis. Amoxycillin administered 6 h after an induced bacteraemia failed to prevent endocarditis in five (38%) of 13 rabbits.

Amoxicillin↗
PubMed1985

Inhibition of monoclonal antibody binding and proteolysis by light-induced phosphorylation of rhodopsin.

Light-induced phosphorylation of rhodopsin in bovine rod outer segment disk membranes inhibits the binding of three carboxyl-terminal-specific anti-rhodopsin antibodies and the cleavage of the carboxyl-terminal region of rhodopsin by trypsin and Staphylococcus aureus V-8 protease. Two monoclonal antibodies, rho 3A6 and rho 1C5, which previously have been shown to preferentially bind to the 8'-12' and the 9'-18' carboxyl-terminal segments of rhodopsin, respectively, are both highly sensitive to phosphorylation. When an average of one phosphate is incorporated per rhodopsin, the binding reactivity of rhodopsin for these antibodies decreases to 30% that of nonphosphorylated rhodopsin as measured in radioimmune competition assays. Reactivity of the rho 1D4 antibody whose primary binding site is localized in the 1'-8' C-terminal segment of rhodopsin is unaffected at this level of phosphorylation but decreases to 30% when three phosphates on average are incorporated per rhodopsin. Direct binding studies using 125I-labeled antibodies indicate that phosphorylation of rhodopsin decreases the maximum extent of rho 3A6 and rho 1C5 binding to rhodopsin. For rho 1D4, the maximum extent of binding is unaffected by phosphorylation, but the dissociation constant is increased by 10-fold. Phosphorylation of rhodopsin also inhibits cleavage of the 1'-9' and 1'-7' carboxyl-terminal peptides by trypsin and S. aureus V-8 protease, respectively. When an average of one phosphate per rhodopsin is incorporated, cleavage decreases to 40% that of nonphosphorylated rhodopsin as measured by high-performance liquid chromatography. Phosphorylation of rhodopsin had no effect on S. aureus cleavage of rhodopsin into the F1 (Mr 25 000) and F2 (Mr 12 000) fragments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Localization of binding sites for carboxyl terminal specific anti-rhodopsin monoclonal antibodies using synthetic peptides.

The binding sites for four monoclonal antibodies, rho 1D4, rho 3C2, rho 3A6, and rho 1C5, have been localized within the C-terminal region of bovine rhodopsin: Asp18'-Glu-Ala16'-Ser-Thr-Thr-Val12'-Ser-Lys-Thr-Gl u8'-Thr-Ser-Gln-Val4'-Ala-Pr o -Ala1'. Antibody binding sites were localized by using synthetic C-terminal peptides in conjunction with solid-phase competitive inhibition assays and limited proteolytic digestion of rhodopsin in conjunction with electrophoretic immunoblotting techniques. Binding of the rho 1D4 and rho 3C2 antibodies to immobilized rhodopsin was inhibited with peptides of length 1'-8' and longer. Antibody rho 1D4 binding was not inhibited by peptides 2'-13' or 3'-18', indicating that the C-terminal alanine residue of rhodopsin was required. Similar competitive inhibition studies indicated that the antibody rho 3A6 required peptides of length 1'-12' and longer whereas rho 1C5 required peptide 1'-18'. Peptide 3'-18' was as effective as 1'-18' in inhibiting rho 3A6 binding to rhodopsin, but replacement of glutamic acid in position 8' with glutamine abolished competition. This substitution had little effect on the binding of antibody rho 1C5. Thus, Glu8' was essential for rho 3A6 binding but not for the binding of the rho 1C5 antibody. Cleavage of the seven amino acid C-terminus from rhodopsin and further cleavage to F1 (Mr 25 000) and F2 (Mr 12 000) fragments with Staphylococcus aureus V8 protease abolished binding of rho 1D4 antibody to the membrane-bound rhodopsin fragments.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1983

Interaction of Escherichia coli F1-ATPase with dicyclohexylcarbodiimide-binding polypeptide.

Antibody raised against the N,N'-dicyclohexylcarbodiimide (DCCD)-binding polypeptide of Escherichia coli bound to the cytoplasmic surface of the cell membrane. A weak reaction was seen with everted vesicles of the thermophile PS3. Rat-liver mitochondrial membranes did not react with the antibody. Reaction of the isolated DCCD-binding polypeptide with the antibody was prevented by oxidation of methionine residues or cleavage of the polypeptide with cyanogen bromide. Modification of the arginine residues of the DCCD-binding polypeptide did not affect interaction with the antibody. Purified F1-ATPase of E. coli bound to the isolated DCCD-binding polypeptide as shown by solid-phase radioimmune assay. Binding involved the alpha and/or beta subunits of F1 and the arginine residues of the polar central region of the DCCD-binding polypeptide. Our results are consistent with a looped arrangement of the DCCD-binding polypeptide in the membrane in which the carboxyl- and amino-terminal regions of the molecule are at the periplasmic surface and the polar central region, interacting with F1, is at the cytoplasmic surface of the cell membrane.

Amino Acid Sequence↗
PubMed1983

Further studies on a hybrid cell-surface antigen associated with human chromosome 11 using a monoclonal antibody.

A monoclonal antibody has been obtained that recognizes an antigen encoded by human chromosome 11. We present evidence that this monoclonal antibody recognizes the same or a similar antigenic activity as that previously called a1. Genetic information necessary for a1 expression and recognition by the monoclonal antibody both map to 11p13 leads to 11pter. Mutants that have lost a1 are no longer recognized by the monoclonal antibody. The macroglycolipid fraction of human erythrocyte membranes which contains the a1 antigenic activity is able to convert antigen-negative Chinese hamster ovary cells into cells which are killed by the monoclonal antibody plus complement.

Animals↗
PubMed1983

Prophylaxis for infective endocarditis: antibiotic sensitivity of dental plaque.

The antibiotic sensitivity pattern of bacteria isolated from bacteraemia after dental extraction was compared with that of bacteria isolated from dental plaque samples from the same patient. The results supported the current practice of using penicillin and erythromycin empirically for prophylaxis. The prediction of the most appropriate antibiotic for prophylaxis using dental plaque samples was most accurate when the minimum inhibitory concentration (MIC) of plaque isolates were used. It appears that a predictive test using dental plaque may be of some value in patients with recent or long-term antibiotic therapy.

Adult↗
PubMed1982

Immunospecific ferromagnetic iron-dextran reagents for the labeling and magnetic separation of cells.

Ferromagnetic iron dextran particles were prepared by reacting a mixture of ferrous chloride and ferric chloride with dextran polymers under alkaline conditions. Particles purified by gel filtration chromatography were in the size range of 30-40 nm, had an electron dense core of about 15 nm, were stable against aggregation in physiological buffer, showed little non-specific binding to cells and had a magnetic moment. Protein A from Staphylococcus aureus was covalently coupled to periodate-oxidized ferromagnetic iron-dextran particles. These conjugates were used to indirectly label antigen sites on human red blood cells and thymocytes for visualization by scanning and transmission electron microscopy. Cells labeled with these immunospecific ferromagnetic particles are were quantitatively retained by a simple permanent magnet and could be separated from unlabeled cells. Applications of these novel reagents in the separation of cells, cell membranes and receptors in drug targeting studies are discussed.

Animals↗
PubMed1982

Organization of rhodopsin and a high molecular weight glycoprotein in rod photoreceptor disc membranes using monoclonal antibodies.

Four monoclonal antibodies obtained from the fusion of mouse myeloma cells with lymphocytes of mice immunized with bovine rod outer segment disc membranes were shown to bind to the surface of sealed discs. Radioimmune labeling of rod outer segment membrane proteins separated by sodium dodecyl sulfate gel electrophoresis indicated that two monoclonal antibodies (3D6 and 4B4) were against rhodopsin. Limited proteolysis of rod outer segment membranes with trypsin and Streptomyces griseus protease indicated that the 3D6 antibody bound to the trypsin-sensitive region close to the carboxyl-terminal end of rhodopsin. The 4B4 antibody bound at a trypsin insensitive, but S. griseus protease-sensitive internal region of rhodopsin accessible on the cytoplasmic surface of discs. Two other monoclonal antibodies (3D12 and 4B2) were found to bind to different regions of the Mr = 220,000 concanavalin A binding glycoprotein of rod outer segment disc membranes. Proteolysis studies indicated that these antibodies also bound to a Mr = 140,000 fragment which does not contain the concanavalin A binding site. Immunoferritin-labeling studies for transmission electron microscopy confirm the location of the 3D6 and 4B2 antigens on the cytoplasmic or interdisc surface of disc membranes.

Animals↗
PubMed1979

Massive hemoptysis secondary to flow-directed thermodilution catheters.

Hemoptysis is an unusual complication of flow-directed (Swan-Ganz) catheters. Over-inflation of the balloon with a shearing-induced rupture of a small pulmonary artery, and the spear effect of the catheter tip appear to be the mechanisms in the two cases presented. Diligent care to avoid overinflation of the balloon in the pulmonary capillary wedge position by observation of the pressure waveform is critical. The spear effect that is frequently seen during insertion may be eliminated by deflating the balloon at the first appearance of the pulmonary artery waveform and gradual advancement of the catheter five to eight cm, when the balloon is then reinflated to obtain the wedge.

Aged↗