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Biomedical subjects

S Garrett

Publications and source records attributed to S Garrett.

At least 91 records · Page 5Linked to original sources
PubMed1986

cis-acting sites required for osmoregulation of ompF expression in Escherichia coli K-12.

OmpF and OmpC are major outer membrane proteins which form passive diffusion pores in Escherichia coli K-12. The expression of the structural genes for these proteins, ompF and ompC, is influenced by medium osmotic strength and requires the products of two regulatory genes, ompR and envZ. We have constructed a series of ompF-lacZ fusions containing different regions of ompF to determine sites involved with osmoregulation. These fusions were crossed onto a specialized transducing phage and integrated into the bacterial chromosome in unit copy. By measuring the fluctuations of beta-galactosidase activity in lysogens grown in high versus low osmolarity, we have identified three regions which are necessary. Furthermore, we have determined that, although the OmpR activation site is not sufficient, OmpR is probably essential for ompF osmoregulation.

Bacterial Outer Membrane Proteins↗
PubMed1985

Antimicrobial irrigation of deep pockets to supplement non-surgical periodontal therapy. II. Daily irrigation.

106 sites with probing pocket depths 7 mm or greater from 14 patients were treated with plaque control instruction and 1 episode of root planing. Sites in each patient were either irrigated with 2% chlorhexidine or left as non-irrigated controls. Irrigation immediately followed root planing and was repeated daily, by the patient, for 24 weeks. Clinical measurements were made at 12 and 24 weeks, as were gingival washings for determining the number and % of spirochetes. Results at 24 weeks demonstrated that bleeding scores decreased from 91% to 9%; the % of spirochetes dropped from approximately 9% to less than 1%; probing pocket depths decreased from 7.5 to 4.5 mm, and probing attachment levels gained 1.1 to 1.4 mm. The chlorhexidine irrigated experimental group and the non-irrigated control group did not differ significantly in any of the studied parameters. Thus, daily patient-administered chlorhexidine irrigation of deep pockets did not augment the effects of non-surgical periodontal therapy.

Adult↗
PubMed1985

Subgingival spirochete and leukocyte counts as indicators of response to therapy.

The aim of this study was to determine whether changes in probing attachment levels are related to subgingival spirochete or leukocyte counts in periodontal pockets. Following initial clinical recordings and therapy consisting of oral hygiene instruction and root debridement, the probing attachment levels of proximal sites of 120 single-rooted teeth in 7 patients were measured every 3 months for 12 months. The measurements of each site were subjected to regression analysis, which determined whether the site was deteriorating, improving, or non-changing. Subgingival washings were taken of 19 deteriorating, 22 improving, and 127 non-changing sites to determine the number and % of spirochetes and the number of leukocytes at each site. Improved probing attachment levels were associated with reduced numbers of spirochetes and leukocytes. However, the ranges of individual measurements of subgingival washing variables overlapped considerably between groups. Spirochete and leukocyte counts related better to the 12-month probing depths than to changes in probing attachment levels during the preceding 12 months. These findings suggest that none of the tested subgingival washing parameters are suitable indicators of changes in attachment levels on an individual site basis.

Gingiva↗
PubMed1985

Healing after treatment of periodontal intraosseous defects. III. Effect of osseous grafting and citric acid conditioning.

The present study was performed to determine whether the healing of periodontal intraosseous defects could be improved through the combined use of citric acid conditioning of the root surfaces and grafting of autogenous intraoral cancellous bone. 28 proximal defects in 19 patients were treated surgically including acid conditioning of the root surfaces. Another 25 defects in these patients were treated with acid conditioning combined with osseous grafts using the maxillary tuberosity areas as donor sites. Both therapies, e.g., citric acid conditioning alone and acid conditioning combined with osseous grafting resulted in approximately 1 mm gains of probing attachment and probing bone levels. Within the parameters of this study, osseous grafting did not enhance the effect of citric acid conditioning alone. Limited improvement of the treated defects of the present study was obtained in spite of the use of supplementary regenerative techniques.

Adult↗
PubMed1985

Healing after treatment of periodontal intraosseous defects. IV. Effect of a non-resective versus a partially resective approach.

2 regenerative surgical approaches using citric acid conditioning, were compared in the treatment of deep intraosseous periodontal defects. The first approach was non-resective in that no osseous tissue was removed. The second, a partially resective approach, involved reduction of the osseous defect depth by removal of some supporting bone. 16 patients and a total of 26 defects, with probing pocket depth greater than or equal to 7 mm, were included in the study. The depths of the corresponding osseous defect, as revealed during surgery were greater than or equal to 5 mm. The results demonstrated mean gains in probing attachment level of 0.7 mm for the partially resected group and 1.1 mm for the non-resected group. Corresponding gains in probing bone levels were recorded in the defect sites for each group. Probing pocket depth was reduced from 7.5 mm to 4.0 mm in the partially resected group and from 7.9 mm to 5.3 mm in the non-resected group. Both procedures caused loss of attachment and bony support from adjacent tooth surfaces involved by the surgical procedure. Slightly more loss of attachment and bone was experienced by the partially resected group (range 1.2-1.5 mm) than by the non-resective group (range 0.1-0.9 mm).

Adult↗
PubMed1985

Antimicrobial irrigation of deep pockets to supplement oral hygiene instruction and root debridement. I. Bi-weekly irrigation.

64 sites with probing pocket depth greater than or equal to 6 mm from 11 patients were treated with plaque control instruction and one episode of root planning. Subsequently, selected sites in each patient were irrigated with either chlorhexidine, tetracycline, saline or served as non-irrigated control sites. Irrigation immediately followed instrumentation, and was repeated every 2 weeks for 24 weeks. Healing was monitored at 8, 16, and 24 weeks clinically and at 7, 15, and 23 weeks with subgingival washings for determination of % as well as total number of spirochetes. The following changes were apparent from comparing pooled site means at 24 weeks with pretreatment data: (1) bleeding sites decreased from 62 of 64 sites initially to 22 of 64 at 24 weeks; (2) spirochetes decreased from 34% to 2%; (3) probing pocket depths decreased from 7.6 to 4.7 mm; (4) probing attachment levels showed a gain of 1.2 mm. The improvement of the chlorhexidine and tetracycline irrigated sites was similar to that of the saline irrigated and non-irrigated control sites. Thus, biweekly chlorhexidine, tetracycline or saline irrigation of deep pockets did not appear to augment the effects of non-surgical periodontal therapy.

Adult↗
PubMed1985

Healing after treatment of periodontal intraosseous defects. VI. Factors influencing the healing response.

84 periodontal intraosseous defects treated with mucoperiosteal replaced flap surgery and citric acid root conditioning were used to study the relationships between various defect characteristics and the healing response as expressed by change of probing attachment level, change of probing bone level and residual probing depth. More gains in probing attachment and probing bone levels were observed in deep defects than in shallower lesions. Other defect characteristics showed weak or no correlations to defect fill. The findings of this study seem to indicate that the outcome of treatment of intraosseous defects may be difficult to predict based upon evaluation of defect characteristics.

Adult↗
PubMed1985

Significance of probing force for evaluation of healing following periodontal therapy.

The present report compares pre- and postoperative probing pocket depths and probing attachment levels in deep pockets treated non-surgically as well as surgically using probing forces at 0.25 N, 0.50 N and 0.75 N. The results demonstrated that the recorded mean pre- and postoperative probing depths were deeper with increasing probing force. In deep preoperative pockets, the difference amounted to as much as 2.0 mm comparing measurements at 0.25 N and 0.75 N. The use of 0.25 N for evaluation of therapy showed less mean pocket reduction and probing attachment gain than the use of 0.50 N or 0.75 N. Selection of a higher probing force before therapy (i.e. 0.75 N) and a lower force after therapy (i.e. 0.25 N) resulted in increased values for pocket reduction and probing attachment gain compared to use of the same probing force for both pre- and postoperative recordings. The findings emphasize the significance of using a known and standardized probing force for evaluation of results following periodontal therapy.

Dental Scaling↗
PubMed1985

Isolation and characterization of delta ompB strains of Escherichia coli by a general method based on gene fusions.

We isolated a series of delta ompR delta envZ mutants by inducing a strain carrying a lambda prophage in the closely linked gene malP and screening the bacterial survivors for loss of the major outer membrane porins OmpF and OmpC. Characterization of these deletion strains showed that both OmpR and EnvZ were necessary for transcription of ompF and ompC and that neither gene was essential for cell viability. Moreover, the deletion strains did not exhibit the pleiotropic membrane protein deficiency observed with certain envZ mutants. The method described should allow the simple isolation of deletions in any region of the chromosome.

Bacterial Outer Membrane Proteins↗
PubMed1985

Mutations that define the promoter of ompF, a gene specifying a major outer membrane porin protein.

Expression of the major porin structural genes, ompF and ompC, is influenced by medium osmotic strength and requires the products of two regulatory genes, ompR and envZ. To help define the sites required for the expression of both porin genes, we have used a novel selection to identify mutations that decrease ompF transcription. From our assignment of the mRNA start site by the primer extension method, these mutations appear to delineate poorly conserved -10 and -35 consensus promoter regions. In addition, one mutation provides the first genetic evidence that an A residue at position -45 may be important for RNA polymerase recognition.

Bacterial Outer Membrane Proteins↗
PubMed1985

Oral rehydration therapy for acute diarrhea in ambulatory children in the United States: a double-blind comparison of four different solutions.

Oral rehydration solutions containing 50 to 90 mmol/L of sodium have recently been recommended for the treatment of diarrhea in both hospitalized and ambulatory children in the United States. Few data are available, however, from ambulatory US children. Therefore, we conducted a randomized double-blind study comparing the use of four different oral rehydration solutions with differing concentrations of sodium, glucose, and base. Ambulatory children less than 2 years of age with acute diarrhea (N = 140) were randomly chosen to receive solutions containing sodium at 90 (solution A), 50 (solution B), and 30 mmol/L (solutions C and D). All oral rehydration solutions contained 20 g/L of glucose except solution D which contained 50 g/L of glucose. Solution A contained bicarbonate as its base source whereas the other three contained citrate. All but three (98%) children were treated uneventfully according to the study protocol, and there were no differences among groups in measurements of clinical outcome. It was concluded that in ambulatory US children, oral rehydration solutions containing 90, 50, or 30 mmol/L of sodium can be used safely for the treatment of mild acute diarrhea and that citrate is as efficacious as bicarbonate in the correction of acidosis.

Ambulatory Care↗
PubMed1984

Outpatient use of oral rehydration solutions in Apache population: effect of instructions on preparation and contamination.

Oral Rehydration Solutions (ORS) containing 90 and 50 mmol/L sodium have recently been recommended for use in ambulatory children in the U.S. These solutions are now marketed in powder form by some commercial companies. However, few data are available in the U.S. on the accuracy with which the solutions are mixed at home or on the bacterial contamination that may occur during mixing. We evaluated the effect of various forms of instructions on the occurrence of bacterial contamination and accuracy of mixing ORS at home by mothers of patients who were dispensed the dry ingredients of an ORS containing 90 mmol/L sodium at the U.S. Public Health Service Hospital, Whiteriver, Arizona. Patients were randomized to one of the four following groups: group I (23 patients) was given written instructions for mixing the solution along with a pre-marked container; group II (22 patients) was given written instructions only; group III (22 patients) was given a premarked container only; and group IV (19 patients) was given neither. All patients were given oral instructions in the preparation of ORS and were asked to refrigerate the reconstituted ORS. We collected samples of ORS at the patient's home 1 day after the clinic visit, to measure their electrolyte content and to identify any bacterial contamination. Mean Na+ concentrations were significantly lower in the ORS prepared by mothers/guardians in groups that were not given a premarked container [82 +/- 13 (II) and 79 +/- 21 (IV) mmol/L vs. 88 +/- 13 (I) and 92 +/- 14 (III) mmol/L; p less than 0.01].(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1983

Relative effects of plaque control and instrumentation on the clinical parameters of human periodontal disease.

The healing events of 7 patients with generalized chronic periodontitis were monitored clinically during 3 consecutive phases of treatment: 1) tooth brushing and flossing, 2) subgingival use of the Perio-Aid, and 3) supra and subgingival instrumentation. The clinical parameters evaluated were plaque score, bleeding score, probing pocket depth, probing attachment level, and gingival recession. Each phase continued until maximum effects were achieved (5, 3, and 9 months respectively) determined by minimal or no changes in bleeding scores and probing pocket depths between 3 successive examinations. The results showed limited improvement in the bleeding scores and probing pocket depths with tooth brushing and flossing only (Phase 1). During use of the Perio-Aid (Phase 2), there was no additional improvement, but the initial limited gains made during Phase 1 were maintained. By the end of Phase 2, however, a slight loss of probing attachment level was noticeable. After instrumentation (Phase 3), there was further and more pronounced improvement in bleeding scores and probing pocket depths, as well as a reversal of the probing attachment loss. The results of this study indicate that significant improvement in periodontal pockets should not be expected following home care procedures alone, and that instrumentation may account for the bulk of improvement seen following a combined therapy of plaque control and instrumentation.

Adult↗
PubMed1983

Isolation and characterization of chain-terminating nonsense mutations in a porin regulator gene, envZ.

We isolated four independent amber mutations in gene envZ, whose product is involved in the regulation of porin protein genes ompF and ompC. The envZ amber strains exhibit an OmpF-/+ OmpC- porin phenotype and express other envelope protein genes at wild-type levels. This phenotype is clearly different from that of the previously isolated class of envZ mutants that exhibit an OmpF- OmpC+ phenotype and a pleiotropic decrease in the expression of several exported protein genes, including lamB and phoA. The addition of the local anesthetic procaine to wild-type strains also causes a pleiotropic decrease in the expression of genes ompF, lamB, and phoA. However, procaine has no effect on the synthesis of LamB or PhoA protein in the envZ amber strains. Thus, although EnvZ protein is required for the full expression of ompF and ompC, it apparently is not normally involved in the expression of other envelope protein genes. One interpretation of these results is that the EnvZ protein can be altered either by mutation or by procaine to a form that interferes with the expression of several envelope protein genes other than ompF and ompC. Finally, complementation analysis with ompR insertion mutations supports the physical data of Mizuno et al. (J. Biol. Chem 257:13692-13698, 1982) that suggest that envZ is cotranscribed with ompR from a single promoter in the order ompR envZ.

Bacterial Outer Membrane Proteins↗