Interproximal access efficacy of three manual toothbrushes with extended, x-angled or flat multitufted bristles.

PURPOSE: This laboratory research study was conducted to evaluate three manual toothbrushes for their ability to remove artificial plaque from interproximal sites. MATERIALS AND METHODS: Interproximal access efficacy (IAE) was evaluated using a pressure-sensitive artificial plaque substrate placed around simulated anterior and posterior teeth with horizontal and vertical brushing motions. Efficacy was determined as the maximum width of artificial plaque removed from around the teeth. Testing was conducted on three manual toothbrushes with different bristle configurations coded as: Extended [Aquafresh Between Teeth (also marketed as Dr. Best Zwischenzahn)], X-angled (Oral-B CrossAction) and Flat multitufted (Oral-B Indicator). Twenty-four tests on each toothbrush design were conducted, and the results were statistically analysed using two-sample t-tests, assuming unequal variances. RESULTS: The individual mean IAE values on anterior and posterior tooth shapes with vertical and horizontal brushing were significantly (P < 0.001) higher for the toothbrush with extended bristles (Aquafresh Between Teeth) than for the other two toothbrush designs tested. When the data were combined to give an overall average, the IAE for the toothbrush with extended bristles (Aquafresh Between Teeth) was significantly (P < 0.001) higher than the IAE value for the toothbrushes containing x-angled (Oral-B CrossAction) or flat multitufted bristles (Oral-B Indicator). CONCLUSION: Based on the demonstrated predictability of the IAE assay for clinical interproximal plaque removal, the manual toothbrush with extended bristles should be an effective brush for cleansing the dental interproximal sites.

Use of two calcium concentrations in hemodialysis--report of a 20-year clinical experience.

Over the past almost 50 years several calcium concentrations in the dialysate (CaD) have been used to balance calcium in hemodialysis (HD) patients but a consensus as to which is most appropriate has not been established. Moreover, since the late 1980s, further confusion has been caused following the use of calcium salts as intestinal phosphate binders. This paper reports results of 387 chronic HD patients with respect to secondary hyperparathyroidism (sHPT) and renal osteodystrophy (ROD) of a single center over 20 years. The most important therapeutic measures applied were use of only 2 CaD, 1.5 and 1.75 mmol/l, with very few exceptions, administration of either calcium-containing or calcium-magnesium-containing and/or calcium-free phosphate binders, no dietary restrictions and continuous compensation of uremic acidosis via dialysate and oral supplements of bicarbonate. Using one of the two CaD and selective administration of different phosphate binders for fine adjustment of serum calcium through this combination, we were able to maintain in the long term almost physiological conditions. With exception of the phosphate metabolism, most physiological functions with regard to sHPT and ROD returned close to normal. As a result, the incidence of hypercalcemia, hypocalcemia, extraosseous, extravascular calcification, bone pain and spontaneous bone fractures was extremely low. We conclude that the clinical advantages of the therapeutic measures, above all precise balance of calcium homeostasis, in our investigation were demonstrated by high survival rates (92% after the first year on HD, 82% after 2, and 55% after 5 years), low incidence of cardiovascular fatalities (about 25%), and very low incidence of sHPT (mostly normal parathyroid hormone levels, 1 parathyrdoidectomy within 20 years).

Kt/V a measure for quality control of haemodialysis therapy: how valid is it?

Since the beginning of maintenance haemodialysis many attempts have been made to quantify this kind of renal replacement therapy. The most widely used methods are urea kinetic models and simple approximation formulae based on measured data of the individual patients. The most common term of dialysis dose is Kt/V. The errors of data put into the calculations are transferred to the result. Analysis of the error of the calculated result depending on the errors of the primary data using Gauss' law of progression of errors reveals errors of the calculated Kt/V between 7.7% and 18%. It is concluded that comparison of different groups of dialysis patients by means of Kt/V should only be done using one method with the least error.

Effect of feeding T-2 toxin contaminated feed on the utilisation of vitamin E in chickens.

The purpose of the present study was to investigate the effect of experimental T-2 toxin load (2.35 mg/kg of feed) and vitamin E supply in the drinking water (10.5 mg/bird/day) on vitamin E levels of the blood plasma and liver in broiler chickens in a 14-day experiment. It was found that T-2 toxin load did not influence vitamin E content of the blood plasma except at day 3 after the toxin load when a moderate increase was detected in plasma vitamin E. No significant changes were found in vitamin E content of the liver. The simultaneous use of high-dose vitamin E supplementation and T-2 toxin load caused a significantly higher plasma vitamin E content but the changes were less expressed in the group subjected to T-2 toxin load. Vitamin E supply also resulted in a marked and significant increase in vitamin E concentrations of the liver on days 3 and 7 even in the T-2 loaded group, but this concentration significantly decreased thereafter. The results show that T-2 contamination of the diet has an adverse effect on the utilisation of vitamin E in broiler chickens.

Diacap alpha-polysulfone HI PS: a new dialysis membrane with optimum beta2-microglobulin elimination.

BACKGROUND: Plasma concentration of beta2-microglobulin (beta2-m) in the case of renal insufficiency is about 20 to 30 times higher than normal. Beta2-m is associated with secondary amyloidosis, a late complication of regular dialysis therapy. To prevent the complications of secondary amyloidosis beta2-m should therefore be eliminated as efficiently as possible during dialysis treatment. This can be accomplished with dialysis membranes which guarantee sufficient clearance for this molecule. It is a matter of discussion whether removal of beta2-m by dialysis may be able to prevent secondary amyloidosis. METHODS: The dialyzers Diacap HI PS 15 (B. Braun Melsungen) and F70 S (Fresenius Medical Care) were compared in five anuric dialysis patients. Arterial blood was taken at the start and at the end of dialysis. Dialysate samples were taken after 30 and 210 minutes and filtrate samples after 60 and 240 minutes from the start of dialysis. Beta2-m and total protein concentration were measured in plasma, filtrate and dialysate. SDS-PAGE of proteins in the filtrate was carried out and kinetics of beta2-m (Kt/V(beta2-m)) were calculated using the Stiller/Mann model. RESULTS: In both dialyzers beta2-m is detectable at any time in the dialysate leaving the dialyzer. In the filtrate beta2-m concentration is about 10 times higher than in the dialysate. Protein pattern in filtrate of both dialyzers is similar and corresponds to that of the glomerulum filtrate. Beta2-m reduction ratio is slightly lower than urea reduction ratio. Using both dialyzers Kt/V(beta2-m) was 0.80, removing about 60% of the generated beta2-m. CONCLUSIONS: In both dialyzers there is considerable removal of beta2-m. Examination of beta2-m kinetics showed an optimum of Kt/V(beta2) of 0.80 which can not be surpassed. Only 60% of generated beta2-m can be removed by three times per week hemodialysis therapy using high-flux dialyzers.

A comparison of the plaque-inhibitory properties of stannous fluoride and low-concentration chlorhexidine mouthrinses.

BACKGROUND: Plaque inhibition by chlorhexidine (CHX) rinses is dose related with a relatively flat dose-response curve above 5-6 mg twice daily. Low dose regimens could therefore reduce local side effects but maintain reasonable efficacy. AIMS: To compare the plaque inhibitory properties of two low-dose CHX rinse products with more conventional levels delivered from proprietary rinses. A secondary outcome was a comparison with a stannous fluoride/amine fluoride (SFAF) rinse product. METHODS: The study was a five-treatments, negative controlled, randomised, single blind crossover design balanced for residual effects, involving 20 healthy subjects in a 24-h plaque re-growth model. On day 1 of each study period, subjects were rendered plaque free, suspended tooth cleaning and followed the appropriate rinse regimen. On day 2, subjects were scored for plaque by index and area. The rinse codes and rinsing regimens were: (A) 15 mg CHX 2 x daily for 30 s (0.1% CHX), (B) 9 mg CHX 2 x daily for 60 s (0.06% CHX), (C) 10 ml SFAF rinse 1 x daily for 30 s, (D) 15 ml placebo 2 x daily for 60 s, and (E) 6 mg CHX 2 x daily for 30 s (0.06% CHX). RESULTS: Average mouth plaque indices and areas were highly significantly different between rinsing regimens. All test rinses were significantly more effective than the placebo rinse. There was a mean dose-response pattern for the CHX rinses, but there were no statistically significant differences between any of the test rinses. CONCLUSIONS: Lower doses of chlorhexidine in rinses can be used to exert plaque inhibition comparable with products used at higher doses and equivalent to benchmark products such as the SFAF rinse. However, the availability of chlorhexidine from formulations has to be considered as in part explaining the results.

Validation of a two-pool model for the kinetics of beta2-microglobulin.

UNLABELLED: Secondary amyloidosis due to beta-2-microglobulin (beta2-m) is a serious long-term complication in patients on regular dialysis therapy. Beta2-m can be considered a middle-molecule marker used to facilitate the assessment of dialysis efficacy. For this purpose, a validated model that calculates characteristic efficacy parameters, such as Kt/V, TAC and generation rate, is needed. There is general agreement that beta2-m-kinetics should be described by a two-pool model, but little has been published to validate such an approach. We measured the beta2-m concentration profiles of eight stable patients during hemodialysis (HD) at the start of treatment, after 30 minutes, after 60 minutes, and every hour until the end. Thereafter they were measured at 10-minute intervals for an hour. The dialyser clearances were determined from the plasma concentrations in front of and behind the dialyser twice during each session - after 1 hour, and 4 hours from the start of treatment. The kinetic parameters of a two-pool model (e.g. the compartment volumes V1 and V2, the mass transfer coefficient K12 and the generation rate G) were determined from the optimal fit of the measured concentration profile. The table below summarises the results by giving the mean and standard deviation for each parameter: [table: see text]. Inter-individual differences in V1/V2 and K12 were high, ranging from 2.5 to 10.0 for V/V2 and from 26 to 140 for K12. Error analysis suggested that these wide ranges were due to the method and that in reality the probable range of V is 25-36% of TBW, of V1/V2 3.5-5.3, and of K12 30-80 ml/min. With standard values for these three parameters (V = 30% of TBW, V/V2 = 4.4 and K12 = 55 ml/m), equal for all patients, and their respective ranges, Kt/W can be calculated with a standard deviation of 13%. Kt/W > 1.2 secures the maximum possible beta2-m removal with three HD treatments a week. CONCLUSIONS: The parameters of a two-pool model of beta2-m kinetics can be derived from concentration profiles obtained under routine dialysis conditions, but accuracy is not completely satisfactory. Similar to the dialysis dose for urea (Kt/Vurea) the dialysis dose for beta2-m (Kt/Vbeta2-m) can be calculated from the pre- and post-dialysis concentrations of beta2-m, body weight, ultrafiltration and dialysis time. Kt/Vbeta2-m > 1.2 secures the maximum possible removal of beta2-m in HD with three sessions per week.

Sodium and body fluid homeostasis in profiling hemodialysis treatment.

Acute adverse side-effects of hemodialysis such as hypotension, muscle cramps, osmotic imbalance and thirst are induced by the interference with fluid and electrolyte balance occurring during treatment. Changes in osmolarity due to alterations of plasma sodium concentration during hemodialysis strongly influence fluid distribution between extracellular and intracellular fluid volume. Increased sodium dialysate concentration induces fluid shift from the intracellular to the extracellular compartment. This shift leads to a more efficient ultrafiltration by increasing plasma refilling volume but also to an increased thirst. Treatment of hypotension, cramps and nausea with hypertonic saline solution leads also to a considerable retention of sodium. Profiling hemodialysis consists in deliberately changing ultrafiltration and dialysate. sodium in order to combine an efficient ultrafiltration with a balanced sodium handling and to prevent side-effects during treatment. Continuous measurement and control of blood volume seems to be the best method to prevent hypotensive episodes. Profiling of sodium should not be the cause of a positive sodium balance. The clinical benefits of sodium profiling to the patients have still to be proven.

Testing protein permeability of dialysis membranes using SDS-PAGE.

BACKGROUND: Permeability of dialysis membranes for high molecular weight compounds should be similar to that of the glomerular membrane in order to remove uremic toxins like the human kidney does. In order to evaluate permeability of high-flux dialysis membranes SDS-PAGE is applied for examination of filtrate of dialysers during routine dialysis with different membranes. METHOD: SDS-PAGE analysis is performed with silver staining method according to the modification of Melzer (5) and consecutive laser densitometry. RESULTS: The protein pattern of filtrate from dialysis membranes is similar to that of the glomerular membrane containing IgG, transferrin, albumin, alpha-1-microglobulin, retinol binding protein and beta-2-microglobulin. Comparing different membranes there are considerable differences depending on cut-off, charge and adsorption capacity of the particular membrane. In all membranes tested permeability of proteins decreases during one treatment session. CONCLUSION: Protein permeability of high-flux dialysis membranes is similar to the gloemerular membrane but modified according to pore-size, surface charge, adsorption and time on dialysis. In contrast to the glomerular membrane in each of the investigated membranes protein permeability decreases during function.

A critical review of sodium profiling for hemodialysis.

In sodium profiling, the sodium concentration in the dialysis fluid, instead of being constant, follows a time-dependent profile over the course of a hemodialysis session. The main aim of this manipulation is to avoid osmotic disequilibrium by keeping plasma osmolality in the physiological range. Further advantages of sodium profiling are a reduction in the incidence of muscle cramps, improved sodium removal, and improved vascular stability. Many different profiles have been used by various investigators. However, if sodium profiling is not appropriately conducted, sodium accumulation with resulting augmented thirst, increase of interdialytic weight gain, and hypertension may result. Sodium accumulation may, in fact, explain the reduced intradialytic morbidity reported in some short-term sodium profiling studies. Randomized, double-blind studies meeting strict statistical criteria and providing a careful control to maintain equivalent sodium balances between the compared treatments are difficult to perform and have not yet been published. However, because sodium profiling has potential benefits, provided that sodium balance is carefully controlled, it should nevertheless be regarded as a tool that experienced nephrologists can use for the treatment of patients who experience intolerable side effects during standard dialysis.

On-line Urea Monitoring during Hemodialysis: A Review.

In recent years, methods of on-line urea concentration and on-line urea clearance monitoring have been proposed for control of dialysis dose (Kt/V) and protein catabolic rate (PCR) in patients on regular dialysis therapy; these offer an alternative to the established methods of urea kinetics based on pre- and post-dialysis measurements of urea concentration. In contrast to such conventional urea kinetics, the new methods deliver results in real time and treatment parameters can be changed instantly. Three on-line measurement methods are to be distinguished: monitoring of urea concentration in ultrafiltrate, monitoring of urea concentration in dialysate (both yield Kt/V and PCR), and monitoring of urea clearance based on conductivity measurements. Some of these approaches are already applied commercially. Here, these methods are compared using results obtained from laboratory and clinical studies. The on-line methods are found to be more accurate than methods based on pre- and post-dialysis urea concentrations, and to be better suited for clinical routine. This paper outlines the principal methods, reviews the present literature, gives an overview of the applications and compares them to conventional pre- and post-dialysis concentration-based methods of urea kinetics. It is concluded that these methods are likely to find a widespread application in the control of dialysis adequacy.

A randomized trial of magnesium in the emergency department treatment of children with asthma.

STUDY OBJECTIVE: Magnesium sulfate has been shown to benefit asthmatic children and adults with poor responses to initial beta(2)-agonist therapy in the emergency department. We sought to determine whether the routine early administration of high-dose magnesium would benefit moderate to severely ill children with acute asthma. METHODS: This was a randomized, double-blind, placebo-controlled trial of 54 children 1 to 18 years of age who presented to the ED of a tertiary care children's hospital with a moderate to severe asthma exacerbation. After receiving a nebulized albuterol treatment (0.15 mg/kg) and methylprednisolone (1 mg/kg), patients were randomly assigned to receive either 75 mg/kg of magnesium sulfate (maximum 2.5 g) or placebo. Thereafter, all patients were treated with frequent nebulized albuterol following a structured protocol. The main outcome was degree of improvement as assessed by Pulmonary Index scores over 120 minutes. Secondary outcomes included hospitalization rates and time required to meet discharge criteria. RESULTS: The mean change in Pulmonary Index score from baseline to 120 minutes was 2.83 for the magnesium group compared with 2.66 for the placebo group (95% confidence interval -1. 24 to 1.60). Eleven (46%) of 24 magnesium-treated patients were hospitalized compared with 16 (53%) of 30 in the placebo group (95% confidence interval -19% to 34%). There were no statistically significant differences between the groups with respect to time required to meet discharge criteria. CONCLUSION: The routine administration of high-dose magnesium to moderate to severely ill children with asthma, as an adjunct to initial treatment with albuterol and corticosteroids, was not efficacious.

Sodium modeling.

The most serious side effects induced by hemodialysis therapy are caused by changes in sodium concentration and subsequent water shift between the intracellular and extracellular fluid compartment. Because of inadequate precision of proportioning, a certain sodium concentration and considerable error in the measurement of sodium concentration in dialysis fluid and plasma water, an error of up to 10 g in the diffusive exchange of sodium chloride remains in most dialysis sessions. Common side effects occur within this sodium balance error. Sodium modeling is a simplified mathematical method to describe quantitatively the fluid exchange in the body caused by changes in extracellular sodium concentration. It is based on fundamental physiologic properties of sodium and its permeability through the corresponding membranes. It also explains the different working mechanisms of sodium- and urea-related changes in osmolarity. Sodium modeling is a helpful tool for the illustration of the effects of changes in sodium concentration and ultrafiltration rate on sodium balance during one dialysis session. Sodium profiling is a method employed to avoid unwanted side effects of hemodialysis therapy by deliberately changing the sodium concentration in dialysis fluid during the course of a dialysis session. Clinical reports on practicing sodium profiling are unsatisfactory, involving only short trial periods in most cases. Most of the studies reported positive sodium balance with temporary decreases in intradialytic hypotension and less blood volume reduction, but with increases in thirst and body weight. To date, no validated studies with suitable control of sodium balance have been published that clearly demonstrate the long-term benefits of this mode of therapy compared with the use of constant dialysate sodium concentrations.

Importance of sodium dodecyl sulfate pore-graduated polyacrylamide gel electrophoresis in the differential diagnostic of Balkan nephropathy.

Balkan nephropathy (BN) is an endemic disease, which leads to end-stage renal failure and artificial renal replacement therapy. Pathologically it is characterized by progressive interstitial nephritis in a large population of villages situated in the proximity of a bend of the Danube up to a distance of 100 km from the river in several parts of Bulgaria, Romania, and the former Yugoslavia. The urinary proteins of 19 patients with BN from the region of Vratza, Bulgaria were examined using ultrathin layer sodium dodecyl sulfate (SDS) pore-graduated polyacrylamide gel electrophoresis (PAGE) and silver staining. The documentation of urinary proteins pattern was performed using laser densitometry and consecutive electronic processing for the purpose of characterizing and quantifying protein excretion. Our results show that the proteinuria of BN is predominantly tubular, consisting of low molecular weight species (10-65 kilodaltons). The amount of tubular protein changes with the progression of the disease. SDS-polyacrylamide gel electrophoresis (PAGE) is a diagnostic method for early diagnosis of tubular failure in BN. Using our method of SDS-PAGE, tubular failure can be detected even at a total protein concentration below 0.1 g/L and when the serum creatinine concentration is normal. Additionally, our method of SDS-PAGE supports the differentiation of BN from glomerular disease.

Rectal administration of N-acetylcysteine in swine: a pilot study.

The purpose of this pilot study was to determine if N-acetylcysteine (NAC) administered via the rectal route in swine is absorbed into the systemic circulation. Fasting swine were anesthetized, intubated, monitored and i.v. access was obtained by femoral cutdown. NAC was administered into the rectal vault (2.0 g/kg) via a balloon-tipped Foley catheter inserted into the animals' rectum. NAC administered via the rectal route resulted in systemic absorption as determined by spectrophotometric methods in 5 of the 7 study animals. This study provides important information regarding the development of a potential alternative route for the administration of NAC.

Metabolism and disposition of a thiazolobenzimidazole active against human immunodeficiency virus-1.

This study was undertaken to evaluate the disposition of the thiazolobenzimidazole, 1-(2,6-difluorophenyl)-1H,3H-thiazolo[3,4-a]benzimidazole (TZB), which has promising antiviral activity. For mice, the maximum tolerated intravenous dose of TZB was 50 mg/kg. An HPLC procedure developed for TZB was used to determine the distribution of the drug. TZB showed no measurable binding to plasma proteins. With intravenous dosing, the kinetic values for TZB in plasma and in each of five tissues were similar in that there was an initial, short alpha-phase (1.8-7.2 min) and a longer beta phase (38-68 min). The concentrations in liver were higher than those in plasma and other tissues. For mice dosed subcutaneously with TZB, the AUC value for plasma was considerably lower than that for mice dosed intravenously; mice dosed intraperitoneally had higher plasma levels of the drug than after oral or subcutaneous dosing. No intact drug could be detected in the plasma of mice dosed topically. After intravenous, oral, or subcutaneous dosing, urinary excretion of intact TZB was < 2% of the dose. Of several vehicles tested in an attempt to increase the plasma levels of unchanged TZB in mice dosed orally, 40% hydroxypropyl beta-cyclodextrin was most effective. Two metabolites present in plasma and urine of mice were tentatively identified as the axial and equatorial sulfoxide isomers of TZB; a third, minor metabolite, was tentatively designated as the sulfone. Although the compound has activity against HIV-1, its low solubility and extensive metabolism reduce its potential for clinical use.