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Biomedical subjects

R Newcombe

Publications and source records attributed to R Newcombe.

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

The effects of 0.5% chlorhexidine and 0.2% triclosan containing toothpastes on salivary bacterial counts.

A number of antimicrobial compounds could be incorporated into toothpastes to enhance plaque inhibitory effects. However, the number of possible formulations is immense and makes clinical testing in plaque and gingivitis studies difficult. In this study, the effects on salivary bacterial counts of a number of chlorhexidine and triclosan toothpastes was evaluated as a predictor of persistence of antimicrobial action in the mouth. The study was a supervised, randomised 15-way crossover study employing 10 healthy human volunteers. All toothpastes were brushed for 1 min and comparison made with a 0.2% chlorhexidine rinse. The latter produced a large drop in salivary bacterial counts to the end of the 7-h study period. The toothpastes decreased salivary bacterial counts and all but two had notably more effect than a water brushing. No toothpaste showed a significant persistence of antimicrobial effect beyond 5 h. In the light of available plaque inhibition data for the toothpastes, persistence of antimicrobial activity beyond 5 h will be necessary for a clinical effect on plaque and gingival health. The method appears to be a simple and rapid screening technique for products formulated to enhance plaque inhibition mediated through an antimicrobial action.

Adult↗
PubMed1990

Comparative effects of toothpaste brushing and toothpaste rinsing on salivary bacterial counts.

The persistence of antimicrobial action of compounds and formulations in the mouth can be demonstrated by recording the magnitude and duration of the reduction of salivary bacterial counts following a single application. Such measures of substantivity appear to correlate with the plaque inhibitory properties of antimicrobial agents. For toothpastes, studies on the short-term inhibition of plaque formation use a number of delivery methods to measure the direct effect of the preparation divorced from toothbrushing. Such methods include paste slurries, paste in trays or cap splints. This study determined whether toothbrushing with a toothpaste produced the same effects on salivary bacterial counts compared to rinsing with a slurry. A group of 24 volunteers brushed or rinsed with a slurry of a commercial toothpaste. Each regimen was repeated twice on 4 separate days by all volunteers and salivary bacterial counts recorded at baseline and time periods to 7 hours. There were no significant differences between brushing or slurry rinsing on salivary bacterial counts and each method produced reproducible effects. This supports the use of the slurry method where the direct plaque inhibitory action of an antimicrobial toothpaste is to be assessed; and indicates that both methods equally make available and activate the relevant ingredients in formulations.

Adult↗
PubMed1989

Structural mechanisms of trabecular bone loss in man.

The relationship between trabecular thinning and loss of connectedness of the trabecular bone pattern has been studied in iliac crest bone samples from 89 normal subjects in order to determine the structural mechanisms underlying age-related bone loss. Trabecular width and structure were quantitatively assessed using computerized techniques. Highly significant negative correlations were found between the mean trabecular plate thickness and number of free ends/mm2 both in males (r = -0.571) and in females (r = -0.667) (P less than 0.001). Mean trabecular plate thickness also showed significant negative correlations with other structural indices indicating reduced connectedness, whereas positive correlations were found with those indices representing preservation of connectedness. Examination of the relative frequency of trabecular widths less than 100 microns revealed that only 2-5% of the trabecular surface would be susceptible to erosion by a resorption cavity of normal depth. These results indicate that trabecular thinning and erosion are interdependent processes in age-related bone loss. Since only a small percentage of the trabecular surface is susceptible to erosion, and resorption cavities normally occupy only 1-5% of the total trabecular surface, these findings imply that the site of activation of new BMUs may not be randomly distributed but may instead be preferentially located at sites of lower trabecular width.

Adult↗
PubMed1989

Thyroid function tests in elderly patients with and without an acute illness.

Thyroid function was assessed by measurement of free thyroid hormones and thyrotrophin (TSH) in 78 acutely ill elderly patients and in a control group without acute illness. Abnormal results with any test were more frequently found in the acutely ill group than in controls. In particular, abnormal TSH values were found in 40% of the acutely ill group and in only 8% of controls (p less than 0.001). Seven acutely ill subjects had very low TSH levels (less than 0.04 mU/l) and a blunted response to thyroid-releasing hormone (TRH). With few exceptions these abnormalities could not be attributed to thyroid disease. This suggests that pituitary TSH secretion can be impaired in euthyroid sick old people. High sensitivity TSH assays may therefore be inappropriate as first-line tests of thyroid function, at least in this select group.

Acute Disease↗
PubMed1989

Studies on the effect of toothpaste rinses on plaque regrowth. (I). Influence of surfactants on chlorhexidine efficacy.

A number of compounds have been added to toothpastes to inhibit plaque regrowth. The inclusion of cationic antiseptics, such as chlorhexidine, poses formulation difficulties because of interactions with other ingredients particularly anionic detergents. More recently, Triclosan/zinc citrate formulations have been shown effective plaque inhibitors. The aim of this study was to compare a commercially available 0.2% Triclosan/0.5% zinc citrate toothpaste with a number of experimental 0.5% chlorhexidine/detergent toothpastes for effects on plaque regrowth over 4 days. Subjects rendered plaque free at each baseline rinsed twice a day with toothpaste slurries and disclosed plaque was scored at the end of each period. All toothpastes significantly reduced plaque by comparison with a control toothpaste, but were significantly less effective than a 0.2% chlorhexidine rinse. Some significant differences in favour of one chlorhexidine toothpaste were noted but these were small in magnitude. Whether the plaque inhibition obtained with Triclosan/zinc citrate toothpaste was greater than would be expected from other commercially available preparations cannot be determined from this study and is the subject of a further investigation.

Adult↗
PubMed1989

Studies on the effect of toothpaste rinses on plaque regrowth. (II). Triclosan with and without zinc citrate formulations.

Encouraging findings have been reported for the effects of Triclosan/zinc citrate toothpastes on plaque regrowth and in some studies gingival health. To date, commercially-available toothpastes contain 0.2% Triclosan with or without 0.5% zinc citrate. The aim of this study was to evaluate the effects on 4-day plaque regrowth, of a number of 0.2% Triclosan toothpastes with or without zinc citrate. All of the toothpastes contained varying levels of anionic detergent sodium lauryl sulphate and were compared with a commercially available toothpaste without Triclosan or zinc citrate and a 0.2% chlorhexidine mouthrinse. The toothpastes were used as slurry twice a day and plaque regrowth scored by area and the criteria of the debris index. Plaque inhibition was significantly greater with the chlorhexidine mouthrinse than with all of the toothpastes. There were no significant differences in plaque scores between any of the toothpastes. It would appear that at the concentration of 0.2% Triclosan with or without 0.5% zinc citrate provides little if any additional benefit to plaque inhibition to that produced by a conventional toothpaste containing sodium lauryl sulphate.

Adult↗
PubMed1989

Comparison of the effect of toothpastes containing enzymes or antimicrobial compounds with a conventional fluoride toothpaste on the development of plaque and gingivitis.

Many toothpastes have been formulated over recent years to contain antimicrobial compounds with the aim of preventing or reducing plaque, calculus, gingival inflammation or dental caries. For many, if not all of these toothpastes, it has yet to be proven whether they are significantly better at reducing plaque and gingivitis than conventional toothpastes, for which no such therapeutic effects have been claimed. This 12-day, incomplete block designed, cross-over study compared the development of plaque and gingivitis following rinsing with toothpaste slurries containing the following active ingredients: (1) hexetidine/zinc citrate, (2) 0.2% triclosan, (3) amyloglucosidase/glucose oxidase, (4) sodium fluoride/sodium monofluorophosphate (NaF, MFP). By the 8th day of the study, a significant difference in gingival crevicular fluid (GCF) and GI was found between the groups. By day 12, however, no significant difference in plaque index and gingival inflammation was found between the 4 toothpastes, although plaque area was significantly reduced with the hexetidine/zinc citrate paste when compared to the conventional fluoride paste. It was concluded that the active ingredients added to the toothpastes evaluated in this study provided little or no more additional benefit to oral hygiene and gingival health than could be achieved with a conventional fluoride toothpaste.

Adult↗
PubMed1989

Toothpastes containing 0.3% and 0.5% triclosan. I. Effects on 4-day plaque regrowth.

Triclosan has been added to toothpaste formulations, alone or with zinc salts, to reduce plaque regrowth. The most encouraging results have been obtained with triclosan/zinc formulations particularly at the higher concentrations of one or both agents. Formulations containing 0.2% triclosan alone have shown less promise and the aim of this study was to measure plaque regrowth over 4-day periods with the use of 0.3% and 0.5% triclosan toothpastes with and without the addition of a copolymer, polyvinyl methyl ether maleic acid (PVM/MA) and to compare the findings with a conventional fluoride/anionic detergent based toothpaste and a 0.2% chlorhexidine mouthrinse. The method was a no oral hygiene randomized 6 times crossover study using the toothpaste slurry rinsing method. Plaque was recorded by a plaque index and by area. Three of the four triclosan toothpastes reduced plaque regrowth significantly compared with the placebo, with no significant differences among the triclosan toothpastes. Plaque scores were always significantly lower with the chlorhexidine mouthwash compared to all toothpastes. The results suggest that at 0.3% to 0.5% triclosan alone or with a copolymer toothpaste may be a benefit to oral hygiene, but whether this is sufficient to affect gingival health requires further clinical evaluation. Further research would also appear indicated to determine optimal levels for the copolymer concentrations in toothpastes.

Adult↗
PubMed1989

Toothpastes containing 0.3% and 0.5% triclosan. II. Effects of single brushings on salivary bacterial counts.

For antimicrobials such as chlorhexidine antiplaque activity appears due to persistence of considerable antimicrobial action in the mouth. The substantivity of antimicrobial compounds can be evaluated by measuring the magnitude and duration of salivary bacterial counts following a single exposure. Such data has been shown to correlate with plaque inhibitory properties of antimicrobial compounds. This study measured the effects of single brushings with 0.3% and 0.5% triclosan with or without PVM/MA copolymer in toothpastes on salivary bacterial counts in 14 young adults. The results were compared with single rinsing with a 0.2% chlorhexidine solution, water and a single brushing with a commercial fluoride toothpaste. The study was a 7 cell cross-over design, randomized using a 7x7 latin square design. Chlorhexidine produced large and significant reductions which persisted to the 7 hour measurement time with no indication of count recovery at this time. The triclosan pastes containing the copolymer produced significant reductions which did not persist beyond 5 hours and evidence of bacterial count recovery with a paste containing triclosan but no copolymer (increments) was apparent after 30 minutes. The water and control paste produced no significant effects on counts. Intertreatment comparisons showed the chlorhexidine rinse more effective than all other preparations in all time periods. Some of the triclosan toothpastes containing the copolymer produced significantly greater effects compared to water or the control paste at some, but not all time periods. There was little difference between the triclosan pastes with the copolymer. Nevertheless, the duration and magnitude of salivary bacterial count reductions seen with the triclosan toothpastes may explain the plaque inhibition effect.

Adult↗
PubMed1988

Relationship between red cell sodium transport, blood pressure, and family history of hypertension.

Numerous studies have demonstrated that Na+/Li+ countertransport is increased in erythrocytes from hypertensive patients. Since Na+/Li+ countertransport is conducted through the physiologically occurring Na+/Na+ exchange, we studied the latter pathway in 20 subjects with essential hypertension and 20 normotensive subjects matched for age and sex. Ten hypertensives and six normotensives had a positive family history of hypertension. Ouabain (0.1 mM) and furosemide (0.1 mM) were used to assess the active Na+ efflux and Na+-K+-Cl- pathway. There was no significant difference between hypertensive and normotensive subjects in any of the three pathways studied. Among the 16 subjects with a positive family history of hypertension, the mean value for external Na+-dependent Na+/Na+ exchange was significantly higher than in 24 subjects with no family history of hypertension (0.0457 +/- 0.0337 versus 0.0283 +/- 0.0202; P less than 0.05). This study suggests that an inherited membrane transport defect may exist for Na+/Na+ exchange in families of hypertensive subjects.

Biological Transport↗
PubMed1988

The antibacterial effect of toothpastes on the salivary flora.

Both past and presently available toothpastes contain potential antimicrobial agents which could have a beneficial effect in the prevention of plaque and gingivitis. If these preparations were to be effective clinically, some effect on salivary bacteria would also be expected. This cross-over study measured salivary bacterial counts and the presence or absence of residual antibacterial activity in saliva following tooth brushing with 7 commercially available toothpastes, and moreover, compared their effect with that produced by a chlorhexidine gel. Generally, all toothpaste products produced a reduction in aerobic, anaerobic and streptococcal counts with a hexetidine containing toothpaste producing the largest and longest lasting reduction. In contrast, an enzyme containing toothpaste and an amine fluoride toothpaste, had little effect on bacterial counts. The chlorhexidine gel produced the largest reduction in salivary counts, which was evident for at least 5 h following brushing. Residual antibacterial activity in saliva was only evident immediately following brushing with the hexetidine toothpaste, but for the chlorhexidine gel, was present up to 90 min following brushing. The findings of this study have illustrated the limited antibacterial activity of presently available toothpastes on the salivary flora compared to chlorhexidine, and as such, would tend to question the relative benefit of toothpaste in preventing periodontal disease through an antimicrobial effect.

Adult↗
PubMed1988

A clinical trial to assess the efficacy of sanguinarine-zinc mouthrinse (Veadent) compared with chlorhexidine mouthrinse (Corsodyl).

A single-blind crossover study was used to compare the ability of a 0.2% chlorhexidine mouthrinse (Corsodyl) with a sanguinarine-zinc mouthrinse (Veadent) to inhibit plaque and gingivitis. 14 volunteers starting with plaque-free mouths and optimal gingival health, rinsed with the preparations over two 19-day periods whilst refraining from all other oral hygiene procedures. At days 8, 15 and 19 of the trial, Corsodyl was significantly more effective at inhibiting both plaque and gingivitis. The findings of this study would suggest that the Veadent mouthrinse would at most only have a limited rôle as an inhibitor of plaque and gingivitis.

Adult↗
PubMed1988

Use of antimicrobial containing acrylic strips in the treatment of chronic periodontal disease. A three month follow-up study.

Local antimicrobial therapy has been considered for use in the treatment of chronic periodontal disease. This study evaluated chlorhexidine, metronidazole, and tetracycline delivered into periodontal pockets in an acrylic resin vehicle and compared the results with root planed and untreated sites over a three-month follow-up period. One site per patient where pocketing greater than or equal to 6 mm associated with a single rooted tooth was randomly allocated to one of the five possible regimens. Baseline and follow-up measurements included probing depth, loss of attachment, bleeding on probing, crevicular fluid flow, and dark-field microscopy of a subgingival plaque sample. Intratreatment evaluations revealed no significant changes in any parameter for untreated sites. Significant improvements in many parameters occurred with all four therapies although the magnitude and duration were greater in metronidazole and root planing groups. The more important intertreatment comparisons indicated that most treatments produced significant benefits compared with the control group; however, again these were greater with metronidazole and root planing. Furthermore, significantly greater effects were noted for metronidazole and root planing compared with tetracycline and more particularly chlorhexidine. It is concluded that some locally delivered antimicrobials alone may be useful in the treatment of chronic periodontal disease. However, at this time local antimicrobial therapy should be considered as adjunctive to conventional debridement techniques.

Adult↗
PubMed1988

The relationship of dietary salt and blood pressure in three farming communities in Kashmir.

The relationship between salt intake and blood pressure was explored in three different areas of Northern Kashmir, where people consume large quantities of salt in tea. Six villages were selected from each area and all the available family members of every second or third house were studied. Food and salt were weighed and the intake of each family member was obtained from the amount consumed out of the total cooked. Complete data were available from 361 subjects (191 males, 170 females). There was no significant difference between the three areas as regards age, height, weight, salt intake and blood pressure. Their age ranged from 15 to 88 yrs (mean 44) and the daily salt intake ranged from 70 to 420 mmol (mean 169 mmol). No correlation was found between age and salt intake or weight but there was a significant correlation between age and systolic blood pressure (r = 0.296; P less than 0.01). Both the systolic and diastolic blood pressure correlated significantly with the salt intake with correlation coefficients of 0.385 and 0.318 respectively (P less than 0.001). Multiple regression analyses showed that the significant relationship between salt and blood pressure was unaltered by adjustment for age. Of the 361 subjects, 46 (12.7%) had a blood pressure of 160/95 mmHg or more. This study suggests a similar relationship between habitual salt intake and blood pressure in each of three different areas of Northern Kashmir.

Adult↗
PubMed1987

Double-blind randomised trial of intravenous glycerol in acute stroke.

The effects of intravenous glycerol in elderly patients with recent onset of acute ischaemic stroke were evaluated in a double-blind randomised controlled trial. 173 patients received either 500 ml of a 10% solution of glycerol in physiological saline or 500 ml of physiological saline administered intravenously over 4 h daily for 6 consecutive days. The number of deaths within the first week was 10 (12%) in the glycerol group versus 26 (30%) in the controls. Subsequent mortality up to 12 months was similar in the two groups and a survival analysis confirmed a beneficial effect of treatment (p less than 0.02). The neurological and functional recovery of survivors, their length of hospital stay, and the proportion able to return to live in their own home were similar in the two groups. The improvement in survival time with glycerol was achieved without serious adverse effects and without an increase in the proportion of survivors with severe residual disability.

Acute Disease↗