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Biomedical subjects

R G Marks

Publications and source records attributed to R G Marks.

At least 55 records · Page 3Linked to original sources
PubMed1989

Visual, refractive, and keratometric results of radial keratotomy. Five-year follow-up.

This article presents five-year findings on the first 156 radial keratotomies in our series. Results are compared with findings on these same eyes at one and three years and with results from other studies. Follow-up at five years was on 123 eyes (79%). Before surgery, the mean spherical equivalent was -5.0 diopters (D). Five years after surgery, the mean change in the spherical equivalent was 5.17 D, and 53% of eyes were within 1 D of emmetropia. Uncorrected visual acuity was 20/200 or worse in 96% of eyes before surgery. At five years, 36% had 20/20 acuity or better, and 75% were 20/40 or better. Best corrected acuity was at least 20/20 in 90% of eyes before surgery. At five years, 85% retained at least 20/20 best corrected acuity. Although some patients still have shown refractive and visual acuity changes through five years after surgery, the overall group has been stable.

Adult↗
PubMed1989

Incidence of hypertension in an ambulatory elderly population.

Investigations of the natural history of blood pressure have generally evaluated mean systolic and diastolic pressure changes. While information, this information is not directly applicable to clinical practice settings, in which patients are usually classified as normotensive or hypertensive. We measured the actual incidence of hypertension, using two different definitions, in an ambulatory elderly population of 2,584 individuals over an 8-year period. Using the less stringent blood pressure definition (systolic blood pressure greater than 140 mmHg and diastolic blood pressure greater than or equal to 90 mmHg), 884 (34.2%) participants were normotensive and 1,700 (65.8%) were hypertensive at an initial screening. The average annual incidence of hypertension over the subsequent eight years was 13.2%, and life tables demonstrated a gradual risk of developing hypertension. The development of hypertension was not associated with gender or age; while older age groups had a greater chance of developing hypertension than younger, the difference did not reach statistical significance.

Age Factors↗
PubMed1989

Efficacy of Perimed antibacterial system on established gingivitis. (I). Clinical results.

A 6-month, double-blind controlled study was conducted on 101 subjects to determine the effect of Perimed antibacterial system, containing povidone-iodine (PVP-I) and hydrogen peroxide (H2O2), on established gingivitis. Subjects were randomly assigned to one of 4 treatment groups: PVP-I/H2O2, PVP-I/H2O, H2O2/H2O or H2O. Gingivitis was assessed by the papillary bleeding score (PBS) and plaque by a modified Quigley-Hein plaque index (PI) at baseline, 3, 12 and 24 weeks. The average baseline PBS and PI for the 4 groups ranged from 2.16-2.31 and 2.87-2.90, respectively. After baseline evaluation, subjects received a supra-gingival scaling and a subgingival irrigation with their respective rinse. Daily rinses were supervised and subgingival irrigation was repeated every 3 weeks. Duncan's multiple range test determined which groups differed from each other. The mean PI at 24 weeks was lower than at baseline in all groups. PVP-I had the lowest PI at all time points. The mean PBS at 24 weeks was 1.48 for PVP-I, 1.62 for H2O2, 1.88 for H2O and 1.34 for PVP-I/H2O2, a reduction from baseline of 31%, 27%, 18%, and 38% respectively. The difference between the PBS for PVP-I/H2O2 and H2O control was significant at each evaluation. There was a 70% reduction in sites with PBS greater than or equal to 3 for PVP-I/H2O2 between baseline and 24 weeks compared to a 34% decrease in the H2O group. It was concluded that the use of Perimed could be a beneficial adjunctive treatment for the prevention and control of gingivitis when used with routine oral hygiene procedures.

Adolescent↗
PubMed1989

Effect of non-surgical periodontal therapy combined with adjunctive antibiotics in subjects with "refractory" periodontal disease. (I). Clinical results.

The aim of the present study was to evaluate the clinical effect of non-surgical periodontal therapy with the adjunct of a selected antibiotic in subjects with refractory periodontitis. 10 subjects were selected for the study; all had a history of periodontal surgery, tetracycline therapy, and regular maintenance by a periodontist. Clinical registrations including gingival index, plaque index, presence of bleeding and suppuration, pocket depth, and duplicate measurements of attachment level were performed at baseline and at monthly intervals. When disease activity was detected based on the tolerance method, a bacterial sample was taken from the active site and its susceptibilities to a number of antibiotics were determined. For the selected 10 subjects, Augmentin was the antibiotic of choice. Each subject received 750 mg/day for 2 weeks, during which time a full-month scaling and root planing was performed under local anesthesia. Clinical re-evaluation was performed after 3, 6, 9 and 12 months. At the time disease activity was detected, the average loss of attachment at all active sites was 2.2 mm, and the increase in pocket depth 1.5 mm. At 3 months post-therapy, these sites had regained 2 mm of attachment which remained stable through the 12-month examination. Pocket depths decreased 2.5 mm over the first 6 months and then stabilized. The frequency of all sites that gained 1 mm or more of attachment increased by approximately 10% over the first 9 months following therapy. The frequency of all sites that decreased 1 mm or more in pocket depth increased approximately 15% over the same period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Modulation of colonization by black-pigmented Bacteroides species in squirrel monkeys by immunization with Bacteroides gingivalis.

Periodontal diseases are inflammatory responses thought to be triggered by specific microorganisms colonizing in the gingival crevice. Theoretically, periodontal diseases could be prevented if the etiologic organisms were not allowed to colonize the subgingival area. The humoral immune response is one mechanism which may modulate bacterial colonization in the gingival crevice. To test the effect of systemic humoral immunity on subgingival colonization by bacteria, squirrel monkeys (Saimiri sciureus) were immunized with Bacteroides gingivalis, a black-pigmented Bacteroides sp. and putative periodontal pathogen. Immunized and sham-immunized monkeys were orally inoculated with 10(10) viable B. gingivalis during ligation of five teeth in one quadrant with bacterium-soaked suture material and distribution over the entire dentogingival margin. Immunization resulted in an increased level of immunoglobulin G anti-B. gingivalis in serum and was associated with a strong trend toward a statistically significant reduction in colonization of the gingival crevice by black-pigmented bacteroides.

Animals↗
PubMed1989

Resting heart rates in an ambulatory elderly population: an evaluation of age, sex, symptoms, and medication.

In a cross-sectional analysis of 2,301 ambulatory elderly subjects, the mean resting heart rate for women (66.2/min) was significantly higher than for men (63.6/min), p less than 0.0001, and heart rate was positively correlated with age for both men and women. Resting heart rate was positively correlated with the number of drugs used (p less than 0.05), number of symptoms reported (p less than 0.05), systolic (p less than 0.01), and diastolic (p less than 0.0001) blood pressure. Of 975 participants who were followed longitudinally over an 8-year period there was a significant decrease in resting heart rate of approximately 2.75/min, p less than 0.0001.

Aged↗
PubMed1988

Two-year results of reoperations for radial keratotomy.

This study compared the two-year results of 320 radial keratotomy surgeries that did not result in reoperations with those of 67 cases that had reoperations. Follow-up was 76% for cases not reoperated and 79% for reoperated cases. Eyes that had reoperations averaged 2.2 diopters more initial myopia than eyes that did not have reoperations, and they averaged 43% myopia correction in the first surgery vs 84% for eyes that did not require reoperations; the reoperation corrected an additional 47% of residual myopia, for an overall 70% correction of myopia in the two surgeries. These results indicated that twice the desired effect of correction should be attempted in a reoperation to achieve the desired result.

Cornea↗
PubMed1988

Interactions between statisticians and biomedical journal editors.

The increased involvement of statisticians in the publication of biomedical research has resulted in increased communication between statisticians and biomedical journal editors. This paper considers ways to enhance positive interactions between statisticians and journal editors. Specific questions addressed are: What are the most serious statistical problems in manuscripts? What statistical design information should the methods include? How can editors identify papers that need statistical review? How can editors interpret what statistical reviewers say? How can editors identify statisticians who are willing to review manuscripts?

Humans↗
PubMed1988

Cataracts in Dunedin Program participants: an evaluation of risk factors.

A geriatric health screening program in Dunedin, Florida, was used to evaluate risk factors leading to development of cataracts. A total of 2,787 participants completed the fourth yearly visit to the program. At the time of the fourth visit, 49.3% of women (mean age 75.1 years) and 38.2% of men (mean age 75.4 years) reported the presence of cataracts. Age was found to be the most significant risk factor in cataract development (P less than .0001). Both men and women with cataracts had significantly lower serum cholesterol concentrations than subjects without cataracts. After adjusting for age and sex, diazepam (P less than .03), furosemide (P less than .04), isosorbide (P less than .003), and ibuprofen (P less than .03) were found to be positively associated with cataracts; triamterene (P less than .05) had a negative association, indicating a protective relationship. Aspirin was not shown to have a protective effect on reported cataracts.

Age Factors↗
PubMed1988

Epidemiology of intermittent claudication: evaluation of risk factors.

Information from a geriatric health screening programme (Dunedin Program) was used to study the prevalence and risk factors predisposing to intermittent claudication (IC) in 1704 ambulatory elderly subjects. Risk factors studied included reported symptoms and diseases, mediation use, haematological and biochemical findings. The prevalence of IC reported by Dunedin participants was 14.1% for women and 14.4% for men. There was a positive relationship between IC and the number of other diseases and symptoms reported (P less than 0.0001). Serum glucose, cholesterol, and triglycerides were significantly higher in subjects reporting IC. Systolic blood pressure was higher in men and women reporting IC, but no significant relationship was observed with diastolic blood pressure.

Aged↗
PubMed1988

Correlation between electronic and visual readings of pocket depths with a newly developed constant force probe.

The purpose of this study was to compare probing measurements obtained using a newly developed constant force electronic probe, which eliminates errors of visual reading and variable force, to those obtained using a standard periodontal probe. The probe was connected to a digital readout through a linear variable differential transformer; the digital readout was connected to a printer and a foot switch. When the probe was in position and the foot switch depressed, the pocket depth was printed to the nearest 0.1 mm. 12 subjects with minimal to early periodontitis were selected for the study. The pocket depths of each patient were recorded electronically utilizing a constant force of 25 g, and conventionally using the same instrument in a "locked" position and visual reading. Probings were performed on each subject by 3 different examiners, on 3 separate occasions 2-3 days apart. The results showed a high correlation between manual and electronic probing. The average correlations for the 3 investigators between examinations were consistently higher for the electronic probings. In comparing the 3 examiners to each other, consistently higher correlations were found for the electronic pocket readings. Correlations for single-rooted teeth were lower for all 3 examiners. The pocket depth measurements recorded when using the manual probe with visual readings were consistently deeper than those obtained using the electronic probe with computer readings. It was concluded that the reproducibility of measurements obtained with the electronic probe was significantly superior to that obtained with a manual probe.

Adult↗
PubMed1988

Attachment level measurements with a constant force electronic probe.

The purpose of the present investigation was to evaluate the reproducibility of probing attachment level measurements using a newly developed constant force electronic probe. The probing force was preset at 25 g (probe diameter 0.4 mm) and was connected to a computer through a variable differential transformer. The measurements were performed on 10 patients with minimal signs of periodontal disease, using individually made acrylic stents. When the probe was in place and a foot switch depressed, the measurement was stored on the computer to the nearest 0.1 mm. The measurements were performed by one periodontist and one hygienist during one visit, and were then repeated by the same periodontist and another hygienist during a second visit. The results showed high correlations between the periodontist and the hygienist during one visit, between the two visits for the periodontist, and between the two hygienists at two different visits. The subject threshold for attachment loss was calculated according to Haffajee and co-workers, and was found to average 0.84 mm for the measurements performed by the periodontist and the hygienist during the same visit. For the periodontist during two separate visits and for the two different hygienists, the average threshold was 0.99 and 1.02 mm, respectively. Duplicate measurements were also performed by one periodontist at one visit on 10 patients with advanced periodontal disease. The average subject threshold for these patients was 0.60 mm. It may be concluded that with the constant force electronic probe, loss of attachment can be detected earlier than when conventional instruments are used.

Dental Hygienists↗
PubMed1988

A 3-year clinical trial to compare efficacy of dentifrices containing 1.14% and 0.76% sodium monofluorophosphate.

A 3-yr daily supervised toothbrushing study with a double blind design was conducted to evaluate the anticaries effectiveness of a 1.14% sodium monofluorophosphate (MFP) dentifrice (1500 ppm F) compared to a 0.76% MFP dentifrice (1000 ppm F). This study began with nearly 4000 children, primarily aged 8-11, in grades 3-5, residing in a nonfluoridated community in Florida. A total of 2415 children completed 3 yr of the study, representing 61% of the children who began the study. The results indicate a statistically significant (P less than 0.001) anticaries benefit was derived over a 3-yr period from the use of the higher fluoride dentifrice (1500 ppm F) when compared to the positive control (1000 ppm F). Percent reductions in mean dental caries increments were 20.9%, 22.1%, 21.8%, 24.3%, and 35.2% for DMFT, DFT, DMFS, DFS, and DFS Interproximal, respectively.

Adolescent↗
PubMed1987

Visual, refractive, and keratometric results of radial keratotomy. A two-year follow-up.

We report two-year follow-up findings on 142 (91%) of the first 156 radial keratotomies performed. The results are contrasted with our earlier six-month and one-year results and with findings from other studies. Mean spherical equivalent before surgery was -5.0 diopters and two years after surgery was -0.10 D; 51% of the eyes were within 1 D of emmetropia. Uncorrected distance acuity was 20/200 or worse in 96% of the eyes before surgery. At two years, 39% had 20/20 acuity or better and 76% had 20/40 or better. At one year, 49% had 20/20 acuity and 76% had 20/40 acuity or better. Refractive results between one and two years showed an overall increase in mean spherical equivalent of 0.23 D. Our results indicate radial keratotomy to be relatively safe and effective two years after surgery.

Cornea↗
PubMed1987

Three-year results of radial keratotomy.

We complied three-year and longer follow-up data on 198 consecutive radial keratotomy surgeries performed by one of us (H.S.). Follow-up was obtained on 138 (70%) of these eyes. Results were compared with previously published two-year results. The mean spherical equivalent before surgery was -4.3 diopters, the average keratometry value was 44.11 D, and 75% of the eyes had an uncorrected distance acuity of 20/400 or more. The average change in the spherical equivalent was 3.74 D for eyes examined at three years, compared with 3.71 D for eyes examined at 18 months. Average keratometry value was 40.96 D after three years, compared with 41.16 D at 18 months. Uncorrected visual acuity was at least 20/40 in 73% of eyes examined after three years, as opposed to 72% at 18 months. For eyes examined at both 18 months and three years, the increase in spherical equivalent of 0.17 D was statistically significant, as was the decrease in average keratometry value of 0.20 D. Uncorrected visual acuity results were stable between 18 months and three years.

Astigmatism↗