Clinical effectiveness of high definition fluorescence camera in detection of initial occlusal caries

Background

Although visual inspection is the preferred route in everyday clinical practise for detecting early caries lesions, novel technologies like light fluorescence-based devices (Vista Proof iX HD smart) have been developed to enhance early caries detection.

Material and Methods

Occlusal surface of 45 molar and 49 premolar teeth from 34 adult participants who fulfilled the eligibility criteria were examined by two observers using three diagnostic methods. Examination was performed visually using the International Caries Detection and Assessment System (ICDAS-II) followed by Vista Proof. Fissurotomy was applied for histological validation. Intra- and inter-observer agreement were measured for ICDAS-II and light-induced fluorescence camera using Kappa test. The overall diagnostic accuracy parameters, area under the receiver operating characteristic curve (AUC-ROC) and 95% confidence interval (95% CI) of the (AUC) for caries detection by Vista Poof were evaluated.

Results

For ICDAS-II and Vista Proof methods, there was almost perfect intra- and inter-observer agreement. Based on ICDAS-II as a reference standard 1, Vista Proof showed a low level of agreement in enamel carious lesion detection with low sensitivity value of 48%, high specificity of 100%, and AUC was 0.112, while a high level of agreement in dentin carious lesion detection with high sensitivity value of 100%, low specificity of 48% and AUC was 0.888. Based on fissurotomy as reference standard 2, Vista Proof showed a high level of agreement in dentin carious lesion detection with high sensitivity value of 95% and 0% specificity and AUC was 0.814.

Conclusions

Quantitative light-induced fluorescence camera with reference to ICDAS-II is considered as an accurate diagnostic modality for detection of early occlusal caries. Histological findings validate the diagnostic accuracy of the camera in dentin.

Key words:Histological validation, Initial caries, ICDAS, Light induced fluorescence, Vista Cam.

Endoscopic management of acute oesophageal variceal bleeding within 12 hours of admission is superior to 12-24 hours

Background: Acute oesophageal variceal haemorrhage (AOVH) is a medical emergency. The American Association for the Study of Liver Diseases recommends endoscopy management as soon as possible and not more than 12 hours after presentation. The United Kingdom guidelines recommended endoscopy for unstable patients with severe acute upper gastrointestinal bleeding immediately after resuscitation and within 24 hours of admission. We aimed to evaluate the outcome of endoscopic management of AOVH in less than 12 hours compared to 12-24 hours post admission.Methods: 297 patients with AOVH were divided into groups depending on the timing of the endoscopic management: 180 within 12 h of admission and 117 patients at 12-24 hours of admission. Routine clinical and laboratory data were collected.Results: Compared to patients with endoscopic management at 12-24 hours (mean 16 hours), patients with endoscopic management within 12 hours (mean 8.3 hours) of admission had fewer hospital stay days (P = 0.001), significant reduction of ammonia levels (P < 0.0001) and significant improvement in associated hepatic encephalopathy grade 25 (p = 0.048). There were no major clinical events in the 12-hour group, but 8 events in the 12-24 hour group (p < 0.01).Conclusion: Endoscopic management of acute variceal bleeding within 12 hours of admission is superior to endoscopic management at 12-24 hours of admission regarding reduction of hospital stay, ammonia levels, correction of hepatic encephalopathy, re-bleeding and mortality rate, hence, reducing the cost of treatment benefiting patient satisfaction and improving hospital bed availability.

A novel approach to identify responder subgroups and predictors of response to low- and high-dose capsaicin patches in postherpetic neuralgia

BACKGROUND

Treatment of chronic pain conditions is commonly assessed at specific endpoints at preset times during or after treatment by analysis of the total study population. An alternative approach is the identification of specific patient subgroups characterized by differential response patterns in their analgesic response and to determine the presence of significant predictors of effect.

METHODS

Data from four double-blind, randomized controlled trials on the efficacy of topical capsaicin 8% (Qutenza) versus an active control (capsaicin 0.04%) in patients with postherpetic neuropathic pain were combined. Longitudinal pharmacodynamic, mixture and covariate analyses were performed on the pooled dataset.

RESULTS

Data from 1248 patients treated with Qutenza (n = 722) or topical low-dose capsaicin 0.04% (n = 526) were successfully analysed. Five distinct response subgroups were detected with different treatment efficacies, including a group of non-responders, a group showing partial analgesic effect and a group showing full analgesic effect. Active control and Qutenza had similar response profiles, but the proportional distribution of patients among the five response groups was in favour of Qutenza, with 40% less non-responders and 25% more patients showing a full analgesic response. For Qutenza, important predictors of efficacy were efficacy of lidocaine pretreatment and greater pretreatment pain score variability.

CONCLUSIONS

The analyses indicate the existence of different response groups to treatment with Qutenza and an active control patch that may possibly be related to different pain mechanisms among these groups, despite a presumed common underlying disease process, and that require different treatment approaches among subgroups.

Guidelines for the quality control of population pharmacokinetic-pharmacodynamic analyses: an industry perspective

Quality population modeling and simulation analyses and reports are something every modeler desires. However, little attention in the literature has been paid to what constitutes quality regarding population analyses. Very rarely do published manuscripts contain any statement about quality assurance of the modeling results contained therein. The purpose of this manuscript is to present guidelines for the quality assurance of population analyses, particularly with regards to the use of NONMEM from an industrial perspective. Quality guidelines are developed for the NONMEM installation itself, NONMEM data sets, control streams, output listings, output data files and resultant post-processing, reporting of results, and the review processes. These guidelines were developed to be thorough yet practical, though are not meant to be completely comprehensive. It is our desire to ensure that what is reported accurately reflects the collected data, the modeling process, and model outputs for a modeling project.

Mechanism-based PK/PD Modeling of the Respiratory Depressant Effect of Buprenorphine and Fentanyl in Healthy Volunteers

The objective of this study was to characterize the pharmacokinetic/pharmacodynamic (PK/PD) relationship of buprenorphine and fentanyl for the respiratory depressant effect in healthy volunteers. Data on the time course of the ventilatory response at a fixed P(ET)CO(2) of 50 mm Hg and P(ET)O(2) of 110 mm Hg following intravenous administration of buprenorphine and fentanyl were obtained from two phase I studies (50 volunteers received buprenorphine: 0.05-0.6 mg/70 kg and 24 volunteers received fentanyl: 0.075-0.5 mg/70 kg). The PK/PD correlations were analyzed using nonlinear mixed effects modeling. A two- and three-compartment pharmacokinetic model characterized the time course of fentanyl and buprenorphine concentration, respectively. Three structurally different PK/PD models were evaluated for their appropriateness to describe the time course of respiratory depression: (1) a biophase distribution model with a fractional sigmoid E(max) pharmacodynamic model, (2) a receptor association/dissociation model with a linear transduction function, and (3) a combined biophase distribution-receptor association/dissociation model with a linear transduction function. The results show that for fentanyl hysteresis is entirely determined by the biophase distribution kinetics, whereas for buprenorphine hysteresis is caused by a combination of biophase distribution kinetics and receptor association/dissociation kinetics. The half-time values of biophase equilibration (t(1/2, k(eo))) were 16.4 and 75.3 min for fentanyl and buprenorphine, respectively. In addition, for buprenorphine, the value of k(on) was 0.246 ml/ng/min and the value of k(off) was 0.0102 min(-1). The concentration-effect relationship of buprenorphine was characterized by a ceiling effect at higher concentrations (intrinsic activity alpha=0.56, 95% confidence interval (CI): 0.50-0.62), whereas fentanyl displayed full respiratory depressant effect (alpha=0.91, 95% CI: 0.19-1.62).

Buprenorphine induces ceiling in respiratory depression but not in analgesia

BACKGROUND

We measured the effect of two weight adjusted i.v. doses (0.2 mg per 70 kg and 0.4 mg per 70 kg) of the potent opioid buprenorphine on analgesia and respiratory depression in healthy volunteers. The aim of the study was to compare buprenorphine's behaviour with respect to the occurrence of ceiling (or apparent maximum) in these typical micro-opioid protein-(MOP) receptor effects.

METHODS

Ten subjects (5 males) received 0.2 mg per 70 kg, 10 others (5 males) 0.4 mg per 70 kg i.v. buprenorphine. Steady-state inspired minute ventilation at a fixed end-tidal Pco(2) of 7 kPa was measured before drug infusion and at regular intervals after drug infusion. Experimental pain was induced using transcutaneous electrical stimulation and a gradually increasing current. Pain tolerance was measured at regular intervals before and after drug infusion. The studies lasted 8 h.

RESULTS

After infusion of the drug ventilation showed a rapid decline and reached peak depression between 150 and 180 min after drug administration. This effect was dose-independent with respect to timing and magnitude. At peak respiratory depression minute ventilation was 13.1 (sd 1.8) litre min(-1) in the 0.2 mg group vs 12.0 (sd 1.3) litre min(-1) in the 0.4 mg group (n.s.). At buprenorphine 0.2 mg a small short-lived analgesic effect was observed with a maximum increase in pain tolerance current of 6.7 (sd 2.8) mA occurring at 75 min after drug administration. Peak analgesic effect was 29% above baseline current. In contrast, buprenorphine 0.4 mg caused a large and long-lived analgesic effect with a maximum increase in pain tolerance current of 23.8 (sd 7.4) mA occurring at 130 min after drug administration. Peak analgesic effect was 160% above baseline current (0.4 vs 0.2 mg, P<0.01).

CONCLUSIONS

While buprenorphine's analgesic effect increased significantly, respiratory depression was similar in magnitude and timing for the two doses tested. We conclude that over the dose range tested buprenorphine displays ceiling in respiratory effect but none in analgesic effect.

Comparison of the respiratory effects of intravenous buprenorphine and fentanyl in humans and rats

BACKGROUND

There is evidence from animal studies suggesting the existence of a ceiling effect for buprenorphine-induced respiratory depression. To study whether an apparent ceiling effect exists for respiratory depression induced by buprenorphine, we compared the respiratory effects of buprenorphine and fentanyl in humans and rats.

METHODS

In healthy volunteers, the opioids were infused i.v. over 90 s and measurements of minute ventilation at a fixed end-tidal PCO2 of 7 kPa were obtained for 7 h. Buprenorphine doses were 0.7, 1.4, 4.3 and 8.6 microg kg(-1) (n=20 subjects) and fentanyl doses 1.1, 2.1, 2.9, 4.3 and 7.1 microg kg(-1) (n=21). Seven subjects received placebo. In rats, both opioids were infused i.v. over 20 min, and arterial PCO2 was measured 5, 10, 15 and 20 min after the start of fentanyl infusion and 30, 150, 270 and 390 min after the start of buprenorphine infusion. Doses tested were buprenorphine 0, 100, 300, 1000 and 3000 microg kg(-1) and fentanyl 0, 50, 68 and 90 microg kg(-1).

RESULTS

In humans, fentanyl produced a dose-dependent depression of minute ventilation with apnoea at doses > or = 2.9 microg kg(-1); buprenorphine caused depression of minute ventilation which levelled off at doses > or = 3.0 microg kg(-1) to about 50% of baseline. In rats, the relationship of arterial PCO2 and fentanyl dose was linear, with maximum respiratory depression at 20 min (maximum PaCO2 8.0 kPa). Irrespective of the time at which measurements were obtained, buprenorphine showed a non-linear effect on PaCO2, with a ceiling effect at doses > 1.4 microg kg(-1). The effect on PaCO2 was modest (maximum value measured, 5.5 kPa).

CONCLUSIONS

Our data confirm a ceiling effect of buprenorphine but not fentanyl with respect to respiratory depression.

Simultaneous quantitative analysis of ketanserin and ketanserinol in plasma by RP-HPLC with ?uorescence detection

A sensitive and selective high-performance liquid chromatographic assay for the quantification of ketanserin and ketanserinol in human plasma was developed and validated. The procedure involves extraction of ketanserin and ketanserinol from plasma using an Extrelut NT-1 solid-phase extraction column. The chromatograph was equipped with a Hypersil BDS column (100 x 4.5 mm, 3 micro m particle size). Separation was performed with a mixture of acetate buffer 0.01 M, pH 4.9-methanol-acetonitrile (52:40:8, v/v/v). Detection was performed with fluorescence detection (lambda(ex) = 332 nm and lambda(em) = 410 nm). Calibration curves were linear (r(2) = 0.999) in the range 0-400 ng/mL for both ketanserin and ketanserinol. The repeatability coefficient for ketanserin and ketanserinol was 3.1 and 3.0%, respectively. The reproducibility coefficient for ketanserin and ketanserinol was 10.5 and 9.1%, respectively. The limit of quantification for both ketanserin and ketanserinol was 2.0 ng/mL. The mean recovery yield for both ketanserin and ketanserinol was 60%. In an 8 h work day approximately 60 samples, including calibration and reference standards, could be processed.

The over-expression of P-glycoprotein in K-562 and DAUDI cells, is associated with a high susceptibility to NK and LAK cells

We evaluated the susceptibility to natural killer (NK) or lymphokine activated killer (LAK) cell-mediated cytolysis of two pairs of drug sensitive/resistant tumor cell lines which were extensively characterized at phenotypic and genotypic level. In the DAUDI cell system, the acquired capability of tumor cell variants to grow in the presence of a relatively high concentration of vinblastine (VBL) is associated with a marked increase to NK and LAK susceptibility. In contrast in the K-562 cell system, no correlation between drug-resistance, P-glycoprotein expression and susceptibility to NK or LAK activity seems to occur.

Expression of lymphocyte homing receptor gene is lost in multi-drug-resistant variants of human T-lymphoblastoid CCRF-CEM cells

The 2.2-kb human cDNA clone PBL32, encoding for the lymphocyte homing receptor (LHR) was used to study the expression of this determinant in multi-drug-resistant (MDR) variants of human T-lymphoblastoid CCRF-CEM (CEM) cells. LHR is significantly associated with the drug-sensitive phenotype, its expression being progressively and quantitatively reduced in MDR variants of CEM cells according to the extent of drug resistance.