Recombinant human erythropoietin in renal transplant recipients with renal anemia

Thirty-seven kidney graft recipients with chronically declining transplant function accompanied by renal anemia were treated with recombinant human erythropoietin for 3 months. In all these patients anemia improved and mean hemoglobin levels increased from 7.67 +/- 1.26 g/dl to 9.83 +/- 1.94 g/dl (p < 0.01). Mean creatinine increased from 4.23 +/- 1.82 to 4.62 +/- 2.42 (p < 0.05) but the progression of transplant failure was not influenced when compared with pretreatment values obtained at least 6 months before study entry. Mean blood pressure levels were not altered but 12 patients required additional antihypertensive medication.

Ion exchange resins for the purification of monoclonal antibodies from animal cell culture

We have compared various ion exchangers for monoclonal antibody (MAb) purification using different starting materials such as ascitic fluid and cell culture supernatant. Twelve cation and anion exchange resins were tested so far. Purification of MAbs with regard to the starting material is described. In well-defined conditions of adsorption (20 mM MES buffer, pH 6.50), one purification step based on cation-exchange chromatography is generally sufficient to achieve at least 90% purity of the MAb, even when produced by animal cell culture. Cation-exchange supports exhibit higher capacity for MAbs compared to anion exchangers. Among the cation exchangers tested, we have selected the cross-linked matrix S Sepharose FF for its large specificity and capacity for MAbs. Considering these key parameters and also the good mechanical resistance of the S Sepharose FF, we describe how, by varying the flow rate, sample concentration, and size of the column, the productivity may be improved in a monoclonal antibody purification process. Finally, a general 'gram scale' purification protocol of MAbs produced by animal cell cultures is proposed. This protocol, based on economical adsorption conditions and three steps of elution (100 mM, 200 mM and 1 M NaCl), allows the recovery of highly purified MAbs.

[Incidence of hypertension in pregnancy in relation to the definition of hypertension]

According to a proposal of the International Society for the Study of Hypertension in Pregnancy (ISSHP) the definition of hypertension is based on a diastolic blood pressure of 90 mmHg or more. Systolic and mean arterial blood pressure (e.g. MAP II) are not be taken into account. Out of a clear defined district the totality of n = 2259 pregnant women has been strictly supervised till to delivery and afterwards. The frequency of hypertension according to the old ACOG-definition was calculated to be 15.9% (n = 360). According to the newer ISSHP-definition it was 12.7% (n = 287). To detect severe and hazardous cases the newer ISSHP-definition seems to be better than the older definition of ACOG. Therefore, the acceptance of the ISSHP-proposal is recommended.

Endothelial control of cell migration and proliferation

The vascular endothelium was found to be involved in numerous physiological and pathophysiological processes and to act as a gating element in between cellular components of the blood and the adjacent tissue. In this respect, endothelial cells are especially important for the control of the extravasation of immune-competent cells and tumour cells and in tissue remodelling. These processes are guided by a network of intercellular recognition and transduction mechanisms in order to guarantee controlled, selective, target-directed action by extravasating cells and for complete functional remodelling of the adjacent tissue. Prostacyclin seems to play an important part in this endothelium-dependent intercellular crosstalk by modulating cell activation without altering the basal cellular mechanisms, as can be shown using stable prostacyclin mimetics, both in animal models and in cell culture.

Effects of dichloroacetate on exercise performance in healthy volunteers

Dichloroacetate (DCA), a stimulator of the pyruvate dehydrogenase complex, decreases lactate levels and peripheral resistance and increases cardiac output. This study was performed to examine the effects of DCA on exercise performance in humans. Eight healthy male volunteers (age 20-28 years) were tested by bicycle spiro-ergometry using a microprocessor-controlled gas analysis system after infusion of DCA (50 mg/kg body weight) or saline. Prior infusion of DCA significantly reduced the increase of lactate levels during exercise when compared with infusion of saline (1.40 +/- 0.21 vs 2.10 +/- 0.09 mmol.l-1 at 50% of the expected maximal working capacity, P < 0.05; 8.53 +/- 0.45 vs 9.92 +/- 0.59 mmol.l-1 at maximal working capacity, P < 0.05). Oxygen uptake increased significantly after DCA when compared with saline from 7.5 +/- 0.4 vs 7.4 +/- 0.5 to 27.2 +/- 1.5 vs 23.7 +/- 1.7 (P < 0.05) at anaerobic threshold and to 35.6 +/- 1.7 vs 30.5 +/- 1.0 ml.kg-1 min-1 (P < 0.05) at maximal exercise capacity. Following DCA infusion the workload at which the anaerobic threshold was reached was significantly higher (160 +/- 7 vs 120 +/- 5 W, P < 0.05) and the maximal working capacity was significantly increased (230 +/- 9 vs 209 +/- 8 W, P < 0.05). In summary, DCA reduced the increase of lactate levels during exercise and increased oxygen uptake at the anaerobic threshold and at maximal working capacity, which was significantly increased. These results warrant further studies on a potential therapeutic application of DCA in patients with reduced exercise capacity.

Time-related changes of in vivo projection errors in standardized radiographs

Subtraction radiography requires radiographs made with identical projection geometry. Recently a new radiographic aiming device and an x-ray beam manipulator made it possible to repeat radiographic exposures in vivo with small angular errors and to measure the angular errors occurring. The purpose of the present investigation was to study in vivo the measuring error and the angular errors produced by this new method at different time points (0, 6, and 12 months) and to assess the effect of different time intervals between exposures (0, 6, and 12 months). Ten sites were investigated. At each time point 2 exposures were made, resulting in 6 radiographs per site. For each pair of radiographs the measuring errors occurring during analysis and the projection errors were determined for each time point and for each time interval. Friedman's test and t-test were used to evaluate the errors. A difference in the measuring error of the system and in the angular errors at the time points 0, 6, and 12 months could not be detected. A time interval between exposures also did not have an effect on the measuring error. Time did not affect the vertical and horizontal angular errors measured between the radiographs producing the smallest oblique error. A combination of radiographs producing the largest oblique angular error showed an increase of the horizontal and vertical angular errors when the time interval increases. These effects, however, were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical furcation diagnoses and interradicular bone defects

The purpose of the present study was to assess associations between clinical depth of involved furcations and their bony defect depth. Twelve patients with moderate to advanced periodontitis in molars were recruited for clinical evaluation of furcation involvement by 6 dentists. Two groups of 3 dentists were assigned to the right or left half of the dentition. All dentists assessed the clinical depth of involvement of the furcations using the Ramfjord index (2 mm) in patients 1 through 6, and using the Hamp index (3 mm) in patients 7 through 12. Diagnoses were made with calibrated and uncalibrated Nabers 2 probes. After the clinical assessments the patients received full mouth scaling and root planing. After reevaluation the molars were surgically exposed. During surgery the depth of the bony furcation defects was assessed using horizontal probing and impressions. Clinically assessed depth of furcation involvement was then compared with the surgical measurements. A total of 1,180 clinical furcation diagnoses were available, of which 426 could be surgically evaluated using both the straight probe and the impressions. These evaluations were done in a total of 72 furcations using probe and impressions. For the Ramfjord index, 5% of the clinical degree 1, 40% of the degree 2, and 43% of the degree 3 readings were overestimations. For the Hamp index, 7% of degree 1, 24% of degree 2, and 0% of degree 3 readings were overestimations. These clinical diagnoses were overestimations. Forty-three percent of surgical degree 3 involvements were not recognized when using the Ramfjord index, and 27% when using the Hamp Index. These results suggest that furcation diagnosis is of limited validity.

Elevated plasma concentrations of lipoprotein(a) in patients with end-stage renal disease are not related to the size polymorphism of apolipoprotein(a)

Patients with terminal renal insufficiency suffer from an increased incidence of atherosclerotic diseases. Elevated plasma concentrations of lipoprotein(a) [Lp(a)] have been established as a genetically controlled risk factor for these diseases. Variable alleles at the apo(a) gene locus determine to a large extent the Lp(a) concentration in the general population. In addition, other genetic and nongenetic factors also contribute to the plasma concentrations of Lp(a). We therefore investigated Apo(a) phenotypes and Lp(a) plasma concentrations in a large group of patients with end-stage renal disease (ESRD) and in a control group. Lp(a) concentrations were significantly elevated in ESRD patients (20.1 +/- 20.3 mg/dl) as compared with the controls (12.1 +/- 15.5 mg/dl, P < 0.001). However, no difference was found in apo(a) isoform frequency between the ESRD group and the controls. Interestingly, only patients with large size apo(a) isoforms exhibited two- to fourfold elevated levels of Lp(a), whereas the small-size isoforms had similar concentrations in ESRD patients and controls. Beside elevated Lp(a) concentrations, ESRD patients had lower levels of plasma cholesterol and apolipoprotein B. These results show that elevated Lp(a) plasma levels might significantly contribute to the risk for atherosclerotic diseases in ESRD. They further indicate that nongenetic factors related to renal insufficiency or other genes beside the apo(a) structural gene locus must be responsible for the high Lp(a) levels.

Cell populations associated with active probing attachment loss

The purpose of this study was to evaluate the ability of cell populations to differentiate between untreated progressing periodontitis sites (P) and untreated non-progressing sites (NP). Pairs of biopsies were obtained from untreated periodontal patients, one biopsy from a site which had lost probing attachment of 2 mm or more within the previous month, the other biopsy from a non-progressing site. Cell populations were identified on 1 micron sections in a defined connective tissue area at the junctional epithelium. The cell types counted were fibroblasts, mast cells, monocytes/macrophages, polymorphonuclear leukocytes (PMNs), lymphoid cells, plasma cells, endothelial cells, total inflammatory cells, and the total number of cells. The number of fibroblasts, mast cells, monocytes/macrophages, and inflammatory cells, as well as their percentage of the total number of cells, differed significantly between P- and NP-sites. In addition, the actual total counts differed between groups. The difference between groups was more significant for percent fibroblasts than for any other cell type. It appears that cell populations, particularly fibroblast counts, can aid in the histological discrimination between P and NP periodontitis lesions.

Biocompatibility of high-flux membranes

Standard dialysis with cuprophane membranes is known to stimulate the immune system. As a result of activation of macrophages various interleukins and tumor necrosis factor (TNF) are secreted, presenting further evidence of the poor biocompatibility of cuprophane. We investigated the immunogenic properties of three modern high-flux membranes. Seven patients were studied during hemodiafiltration sessions using either a polysulfone (F60, Fresenius), a polymethylmetacrylate (BK 2.1, Toray) or a cellulose triacetate (FB-210 U, Nipro) dialyzer in a hemodiafiltration procedure. Serial measurements were made during each treatment of interleukin-1 beta (II-1 beta), TNF, soluble IL-2 receptor (sII-2r), soluble CD4 (sCD4), soluble CD8 (sCD8), interferon gamma (IFNg) and neopterin. In contrast to the known increase of IL-1 beta, IL-2r and TNF with cuprophane membranes, none of the modern high-flux dialyzers stimulated the production of these factors. Significant decreases of neopterin and sCD4 were observed. IFNg and sCD8 did not change significantly. Our results suggest that the modern high-flux dialyzers are non-immunogenic, and thus provide further evidence of the superior biocompatibility of synthetic or semisynthetic membranes over the conventional cuprophane.

Numbers and vitality of leukocytes in pocket washings of untreated periodontitis lesions in humans utilizing a novel intracrevicular lavage technique

The purpose of the present study was to develop an intracrevicular lavage technique, and to use it for assessment of the total number and % of vital leukocytes from untreated periodontitis pockets. A lavage device was developed, consisting of specially crafted cannulas, a vacuum pump and a charge amplifier. In vivo evaluations showed that there was a linear relationship between lavage time and lavage volume; 2-6 lavage samples were obtained from each of 20 patients with untreated advanced periodontitis, and the lavage time was measured in a subsample of 16 pockets. The lavage fluid was centrifuged, and the supernatant was separated from the cellular components. The cells were vital-stained using two methods, trypanblue exclusion method (TB) and ethidium-bromide fluorescein-diacetate stain (EB-FDA). Numbers of vital and non-vital leukocytes per sample were assessed using a Neubauer chamber. The number of erythrocytes per sample was evaluated using the same counting method. The results included 95 samples obtained from the 20 patients: 76% of all samples ranged in pocket depth between 4 and 8 mm. The lavage technique provided an overall mean lavage volume of 282.37 microliters in an average time of 16.44 seconds. The mean number of leukocytes per sample was 22.20 x 10(3) (TB) and 24.48 x 10(3) (EB-FDA). Percent vital leukocytes were 72.27 (TB) and 72.63 (EB-FDA). EB-FDA had a lower counting error than TB. The low erythrocyte counts per sample suggested that subgingival bleeding during sampling was negligible. Spearman correlation coefficients showed weak associations between pocket depth and leukocyte counts, % of vital leukocytes and erythrocytes. Due to the short sampling time this new intracrevicular sampling technique permits sampling of pockets before the tissue responds to the stimulus of the lavage device, and provides subgingival washings with high numbers of leukocytes.

Plasma apolipoprotein A-IV metabolism in patients with chronic renal disease

The plasma concentration and distribution of apolipoprotein A-IV were investigated in normotriglyceridaemic patients with end-stage renal disease and compared with those in a sex- and age-matched control group with normal renal function. A three-fold elevated plasma mean concentration of apolipoprotein A-IV was found in patients with end-stage renal disease treated by haemo- or peritoneal dialysis (58.5 +/- 18.9 mg dl-1 or 50.5 +/- 12.2 mg dl-1, respectively) compared with the controls (18.3 +/- 6.4 mg dl-1). The plasma distribution of apolipoprotein A-IV was studied in patients treated by haemodialysis and in controls by gel permeation chromatography. In the haemodialysis group, 40.3% of the apolipoprotein A-IV was found to be associated with the fraction of high density lipoproteins, whereas the rest (59.7%) was not associated with lipoproteins. This distribution was significantly different from that in the control group (24.8% vs. 75.2%, 0.01 less than P less than 0.05). The elevated plasma concentrations of apolipoprotein A-IV in the patients are not related to triglyceride levels and therefore are unlikely to result from an impaired catabolism of triglyceride-rich lipoproteins. The accumulation of apolipoprotein A-IV in high density lipoproteins from patients with end-stage renal disease might reflect the impaired reversed cholesterol transport mechanisms which are believed to be a major cause of the high prevalence of atherosclerotic diseases in these patients.

Root substance removal by scaling and root planing

The amount of root substance removed by scaling and root planing is largely unknown. The present study evaluated in vitro the root substance loss caused by a defined number of working strokes at known forces. Forty extracted teeth with loss of connective tissue attachment into the middle third of the roots were washed and embedded in plaster, leaving one entire corono-apical tooth aspect exposed. The teeth were reproducibly repositioned in a bench-vise, where a profilometer repeatedly measured root surface levels at the same location. In a standard area of the roots a total of 40 working strokes were applied. Low forces were used in 30 teeth and high forces in 10 teeth. The forces were recorded using a piezo-electric receiver built into the upper shank of the curet. Root substance loss was measured after 5, 10, 20, and 40 working strokes. The results showed that the mean low force used per working stroke across all 40 strokes was 3.04 Newtons for the low forces, and 8.48 Newtons for the high forces. Mean cumulative loss of root substance across 40 strokes was 148.7 microns at low forces, and 343.3 microns at high forces. The mean force per stroke increased slightly across the 40 strokes, while substance removal per stroke decreased. Substance removal per stroke during strokes 1 to 5 was 6.8 microns using low forces and 20.6 microns using high forces. During strokes 21 to 40 mean removal per stroke was 2.3 microns at low forces, and 5.6 microns at high forces. These results suggest that high forces remove more root substance, and loss per stroke becomes less with increasing numbers of strokes.

[Effect of electrically powered dental devices on cardiac parameter function in humans]

Electrically powered devices represent a hazard for patients with cardiac pacemakers. The aim of the present investigation was an in vivo evaluation of possible interactions between electrically powered dental instruments and the function of artificial pacemakers in humans. In 26 patients with artificial pacemakers, different dental instruments were applied, including air scaler, ultrasonic curets, electric pulp tester and electrotome. These devices were applied at highest intensity. Immediately prior to, during, and immediately after applications of these instruments, the pulse rate and the electrocardiogram (EKG) were recorded. The EKG recordings were assessed for irregularities in the distances between the pacemaker peaks. The dental devices were assessed for magnetic fields or induction tension. The results showed that none of the dental devices caused an irregularity in the pacemaker function. The air scaler, Piezon ultrasonic curet and the electric pulp tester caused no measurable magnetic fields. The Sonus 2 ultrasonic curet and the electrotome magnetic fields were measured up to 60 and 50 cm, respectively. All dental devices caused induction tension. The highest value was produced by the electrotome. It seems that cardiac pacemaker function is not affected by electrically powered dental devices. However, there remains a risk in relation to older pacemakers or defective dental devices.

In vivo determination of radiographic projection errors produced by a novel filmholder and an x-ray beam manipulator

Subtraction radiography requires radiographs made with identical projection geometry. The purpose of the present investigation was to develop and evaluate a new in vivo method to measure angular radiographic projection error. This included the development of a system for accurate control of the x-ray beam angulation relative to the intraoral film and the evaluation of the in vivo projection errors (equivalent to the "angular difference" between repeated exposures) produced by the new system. A filmholder, an x-ray beam manipulator, and an aiming device were newly constructed. Reference wires were attached for measuring the projection error on the filmholder and on the 22 bicuspids at the sites of investigation in 16 patients. Two exposures using standardized projection conditions were made of each site. The relative position of the reference wires on the duplicate radiographs was used to calculate the angular difference in the direction of the x-ray beam which occurred between the 2 exposures. Triplicate measurements allowed the determination of measurement error. The angular projection errors were measured in a horizontal and vertical direction. The reference wires allowed determination of the angular projection errors relative to the filmholder, relative to the dentition and the angular error due to the repositioning of the filmholder in the patient's mouth. The average projection errors deviated only slightly from zero. The largest deviation registered was -0.11 degrees. This applies to the horizontal and vertical direction and all relationships. The standard deviations varied between 0.403 degrees and 0.697 degrees. This applies to the standard deviation for all relationships in the horizontal, the vertical, and the oblique directions. The measuring error found from the triplicate measurements had a standard deviation of 0.08 degrees to 0.19 degrees depending on the distance between the reference wires. This new system for controlling in vivo projection errors seems to provide highly standardized radiographs in vivo. The new measuring system proved to be accurate enough to measure the in vivo projection errors between repeated radiographs produced with the new filmholder and x-ray beam manipulator. The in vivo errors produced by the new system are markedly smaller than all in vivo and in vitro errors previously reported in the literature.

Cell populations and episodic periodontal attachment loss in humans

The purpose of the present study was to assess possible associations between episodic probing attachment loss and cell populations in the supracrestal connective tissue in humans. 10 systemically healthy adult patients with untreated advanced periodontitis were monitored during a period of 10 months. At baseline and every month thereafter, probing attachment levels were measured at 6 sites of every tooth using an electronic pressure sensitive probe and flexible stents. Corresponding contralateral sites were identified where 1 site had lost 2 mm or more attachment within the previous month (P), and the other site had not (C). Supracrestal soft tissue biopsies were taken from these sites, processed and cut into 1 micron sections. Cell populations were identified in superficial and deep connective tissue areas by counting fibroblasts, macrophages, plasma cells, mast cells, granulocytes, lymphocytes, endothelial cells and the total number of inflammatory cells. Analysis of variance assessed differences in cell populations between P- and C-sites. There were statistically significantly higher numbers of fibroblasts in the standard areas of C-sites (p less than 0.0001). In P-sites, the numbers of macrophages, plasma cells, mast cells, lymphocytes and total inflammatory cells were significantly higher as compared to C-sites (p = 0.05-0.0001). There were no differences in cell populations between superficial and deep connective tissue areas within P- and C-sites (p greater than 0.2). Clinically assessed episodes of periodontal disease progression may be associated with site-specific shifts in inflammatory cell populations.

Screening of various mammalian cell culture media to establish a downstream purification scheme

Various serum-free media for use in hybridoma cell cultures are reviewed and their protein composition analysed. The chromatographic behaviour of the serum-free components was analysed on ion exchange, hydrophobic and sizing columns in order to facilitate the design of a purification scheme for monoclonal antibodies produced from various cell cultures.

In vivo scaling and root planing forces

The purpose of the present study was to assess the scaling and root planing forces exerted in vivo. Ten dentists and 10 dental hygienists scaled and root planed one aspect of an incisor in an adult patient with untreated advanced periodontitis. During scaling and root planing forces were recorded using a piezo-electric receiver, an electronic transducer, and an analogous writer. The forces were recorded in mA and converted into Newtons (N). The results showed that the mean scaling force applied by dentists was 5.70 N and ranged between 1.01 to 10.35 N. The corresponding values for dental hygienists were a mean of 5.38 N, and a range of 1.52 to 15.73 N. The root planing forces in dentists reached a mean of 4.62 N, and ranged between 0.86 to 8.88 N. For hygienists, these values were 4.58 N with a range of 1.56 to 10.59 N. Negative forces impacting on the periodontal soft tissues were also recorded. They were not present in all therapists, but consistently at work within specific therapists. During scaling these forces reached a mean of -0.40 N in dentists and -0.47 N in dental hygienists. During root planing, these forces were mean -0.59 N in dentists, and -0.81 N in hygienists. There were no statistically significant differences between scaling forces and root planing forces, nor between forces used by dentists and hygienists (P greater than 0.05). However, there were significant differences between the force levels of the individual therapists for all positive forces (P = 0.0001), and for negative forces during root planing (P = 0.0001). The technology and information provided by this investigation may enable studies evaluating clinical effectiveness of scaling and root planing doses.

Some aspects of hybridoma cell cultivation

Two hybridoma cell lines were cultivated in an indirectly aerated 10-1 reactor in batch, fed-batch and continuous (perfusion) operations and in spinner flasks. The medium in the reactor was sampled either by an aseptic cross-flow filtration module integrated into a loop or by an in-situ tubular filter. The glucose concentration was monitored by an on-line flow injection analyser and the ammonia concentration by an ion-selective electrode. Since the membrane transmission of the high-molecular components decreased during cultivation, the product, a monoclonal antibody, was enriched in the reactor. During cultivation, the concentrations of cells, viable cells, glucose, lactase, acetate, citrate, ammonia, urea, amino acids, proteins, and monoclonal antibodies were determined off-line. The specific growth rate, specific production, and consumption rates of the medium components were influenced considerably by the medium composition, especially by the type and amount of serum used.

Hemodynamic effects of partial correction of chronic anemia by recombinant human erythropoietin in patients on dialysis

Eighteen patients on chronic hemodialysis with renal anemia were treated with recombinant human erythropoietin (r-HuEPO). Hemodynamic parameters in the resting state were determined before and after successful treatment. Posttreatment cardiac index was decreased (3.3 v 2.8 L/min/m2), whereas diastolic blood pressure (72 v 79 mm Hg) and calculated peripheral resistance (2,230 v 2,860 dyne.cm.s-5) were increased significantly when compared with the pretreatment period. We conclude from our study that the increase of blood pressure as seen in patients on dialysis, who are effectively treated with r-HuEPO, is due to an increase in peripheral resistance. This increase overrules the decrease of cardiac index and might well be a result of peripheral vasoconstriction due to improved oxygen availability.

[Episodic progression of periodontitis--histologic associations]

Periodontal lesions are primarily diagnosed using the periodontal probe. Using site-specific probing attachment level measurements in defined time intervals, dentists can identify patients and dentition segments that suffer temporarily from a high periodontitis progression rate. The present article describes whether sites where clinical measurements suggested a high progression rate had tissue characteristics different from nonprogressing sites. Ten patients with untreated advanced adult periodontitis were monitored for 10 months by measuring clinical parameters every 30 days. These parameters were gingival index, plaque index, bleeding index, bleeding on probing, probing depth and probing attachment levels. Every month pairs of contralateral sites were sought where one site had lost 2 mm (P-2) or more (P greater than 2) probing attachment (P-sites) and the other site had not (C-site). From these sites supracrestal soft tissue biopsies were taken. After histological processing, a first analysis determined the number of inflammatory cells in 9 standard areas in P- and C-biopsies. A second analysis evaluated cell populations at the apical end of the junctional epithelium. The results showed that bleeding on probing, probing depth and probing attachment loss were statistically significantly greater at P-sites. At C-sites there were only few inflammatory cells. At P-2-sites there were numerous inflammatory cells, and in P greater than 2-sites the number of these cells was statistically significantly greater than in corresponding control sites. The cell populations at the apical end of the junctional epithelium were different between P- and C-sites. At P-sites, the percentage of mast cells, monocytes/macrophages and plasma cells was statistically significantly greater than at C-sites. At C-sites, the percentage of fibroblasts was statistically significantly greater than at P-sites. These results demonstrate that clinical probing identifies episodes of periodontitis progression, which are associated with pronounced changes in tissue characteristics, namely greater numbers of inflammatory cells.

Cross-sectional and longitudinal reliability for clinical measurement of attachment loss

Progression of marginal periodontitis in humans is characterized by acute exacerbations during short periods of time followed by periods of remission. The analytical procedures used to distinguish actively progressing sites from non-progressing sites within an individual's dentition are controversial. The purpose of the present investigation was to use measurements of probing depth and attachment level from a prospective longitudinal study of episodic periodontal disease progression to examine measurement and diagnostic reliability. In 10 systemically healthy adult human subjects with untreated advanced periodontitis, probing depth and attachment levels were measured at baseline and every 30 days for 10 to 12 months. Measurements were made at 6 sites of each tooth using an acrylic onlay as a reference point and a pressure sensitive probe. Replicate measurements were made on sites showing apparent changes in attachment loss of 2 mm or more in a month, and their contralateral counterparts. Cross-sectional reliability was described by means and standard deviations for the absolute differences between replicate measurements: 0.63 +/- 0.87 mm for anterior teeth, 0.58 +/- 0.80 mm for premolars and 0.69 +/- 0.91 mm for molars. The mean differences tended to decrease with increasing time on study and tended to be greater in deeper pockets. Longitudinal reliability was described by analyzing site-specific serial attachment level measurements across the study time period. Maximum likelihood methods were used to estimate false positive and false negative diagnostic rates associated with the diagnosis of attachment loss based on minimum threshold levels of 1 and 2 mm. The use of a 1 mm threshold resulted in estimated false positive rates of 0.08 to 0.11 and false negative rates of 0.11 to 0.15.(ABSTRACT TRUNCATED AT 250 WORDS)