Comparison of intraocular lens power prediction accuracy of formulas in American Society of Cataract and Refractive Surgery post-refractive surgery calculator in eyes with prior radial keratotomy

Purpose

To evaluate the accuracy of intraocular lens (IOL) power prediction of the formulas available on the American Society of Cataract and Refractive Surgery (ASCRS) post-refractive calculator in eyes with prior radial keratotomy (RK) for myopia.

Methods

This retrospective study included 25 eyes of 18 patients whose status was post-RK for treatment of myopia, which had undergone cataract extraction with IOL implantation. Prediction error was calculated as the difference between implanted IOL power and predicted power by various formulae available on ASCRS post-refractive calculator. The formulas compared were Humphrey Atlas method, IOLMaster/Lenstar method, Barrett True-K no-history formula, ASCRS Average power, and ASCRS Maximum power on ASCRS post-refractive calculator.

Results

Median absolute errors were the least for Barrett True-K and ASCRS Maximum power, that is, 0.56 (0.25, 1.04) and 0.56 (0.25, 1.06) D, respectively, and that of Atlas method was 1.60 (0.85, 2.28) D. Median arithmetic errors were positive for Atlas, Barrett True-K, ASCRS Average (0.86 [-0.17, 1.61], 0.14 [-0.22 to 0.54], and 0.23 [-0.054, 0.76] D, respectively) and negative for IOLMaster/Lenstar method and ASCRS Maximum power (-0.02 [-0.46 to 0.38] and - 0.48 [-1.06 to - 0.22] D, respectively). Multiple comparison analysis of Friedman's test revealed that Atlas formula was significantly different from IOLMaster/Lenstar, Barrett True-K, and ASCRS Maximum power; ASCRS Maximum power was significantly different from all others (P < 0.00001).

Conclusion

In post-RK eyes, Barrett True-K no-history formula and ASCRS Maximum power given by the ASCRS calculator were more accurate than other available formulas, with ASCRS Maximum leading to more myopic outcomes when compared to others.

Impact of crossplay between ocular aberrations and depth of focus in topo-guided laser-assisted in situ keratomileusis outcomes

Purpose

To develop a nomogram in cases with mismatch between subjective and Topolyzer cylinder, and based on the magnitude of the mismatch, customize a treatment plan to attain good visual outcomes post-laser-assisted in situ keratomileusis (LASIK) surgery.

Methods

The patients were evaluated preoperatively using corneal tomography with Pentacam. Five optimal corneal topography scans were obtained from the Topolyzer Vario were used for planning the LASIK treatment. For the nomogram purpose, the patients were divided into three categories based on the difference between the subjective cylinder and Topolyzer (corneal) cylinder. The first group (group 1) consisted of eyes of patients, where the difference was less than or equal to 0.4 D. The second group (group 2) consisted of eyes, where the difference was more than 0.4 D and the subjective cylinder was lesser than the Topolyzer cylinder. The third group (group 3) included eyes where the difference was more than 0.4 D but the subjective cylinder was greater than the Topolyzer cylinder. LASIK was performed with the WaveLight FS 200 femtosecond laser and WaveLight EX500 excimer laser. Assessment of astigmatism correction for the three groups was done using Aplins vector analysis. For comparison of proportions, Chi-square test was used. A P value less than 0.05 was considered statistically significant.

Results

The UDVA was statistically significantly different when compared between groups 1 and 2 (P = 0.02). However, the corrected distance visual acuity (CDVA) was similar among all the three groups (P = 0.1). Group 3 showed an increase of residual cylinder by -0.25 D, which was significant at intermediate and near reading distances (P < 0.05). Group 3 showed significantly higher target-induced astigmatism (TIA) compared to groups 1 and 2 (P = 0.01). The mean surgically induced astigmatism (SIA) was the least in group 2, which was statistically significant (P < 0.01).

Conclusion

The outcomes for distance vision using our nomogram postoperatively were excellent, but further refinement for improving the near vision outcomes is required.

Lane-Hamilton syndrome - Is it really a needle in a haystack?

Introduction

The association of pulmonary hemosiderosis with celiac disease (Lane-Hamilton syndrome) is extremely rare.

Case Details

A five-year-old female child presented with fever, cough, breathlessness, and pallor for 20 days, without any previous history of recurrent lower respiratory tract infections, tuberculosis, or cardiac disease. There was no history of pica, chronic diarrhea, bleeding, or personal or family history of repeated blood transfusions. She had tachycardia, tachypnea, severe pallor, stunting, rickets, and bilateral fine lung crepitations. Peripheral smear and blood indices revealed dimorphic anemia. Anti-tissue transglutaminase IgA antibody levels were high (>200 U/mL) and the upper gastrointestinal endoscopy with duodenal biopsy confirmed the diagnosis of celiac disease. The child was discharged on a gluten-free diet (GFD) and oral hematinic, but her dietary compliance was poor. Interestingly, the child had persistent bilateral pulmonary infiltrates, which was initially attributed to congestive cardiac failure (CCF), which persisted even despite treatment. HRCT chest revealed interstitial thickening and bilateral alveolar shadows and bronchoalveolar lavage showed a few inflammatory cells. The child was readmitted four times with similar complaints and was given packed red cell transfusions. In the fourth admission, a lung biopsy was done, which revealed extensive pulmonary hemosiderosis. The patient was given a course of oral steroids for 6 weeks, with a gluten-free diet, following which both the anemia and the pulmonary infiltrates resolved.

Conclusion

Pulmonary hemosiderosis is an important cause of anemia in cases of celiac disease and may be misdiagnosed as CCF due to severe anemia. A strict GFD, with or without corticosteroids, can reverse the clinical and radiological picture.

Safety, infectivity and immunogenicity of a genetically attenuated blood-stage malaria vaccine

BACKGROUND

There is a clear need for novel approaches to malaria vaccine development. We aimed to develop a genetically attenuated blood-stage vaccine and test its safety, infectivity, and immunogenicity in healthy volunteers. Our approach was to target the gene encoding the knob-associated histidine-rich protein (KAHRP), which is responsible for the assembly of knob structures at the infected erythrocyte surface. Knobs are required for correct display of the polymorphic adhesion ligand P. falciparum erythrocyte membrane protein 1 (PfEMP1), a key virulence determinant encoded by a repertoire of var genes.

METHODS

The gene encoding KAHRP was deleted from P. falciparum 3D7 and a master cell bank was produced in accordance with Good Manufacturing Practice. Eight malaria naïve males were intravenously inoculated (day 0) with 1800 (2 subjects), 1.8 × 10⁵ (2 subjects), or 3 × 10⁶ viable parasites (4 subjects). Parasitemia was measured using qPCR; immunogenicity was determined using standard assays. Parasites were rescued into culture for in vitro analyses (genome sequencing, cytoadhesion assays, scanning electron microscopy, var gene expression).

RESULTS

None of the subjects who were administered with 1800 or 1.8 × 10⁵ parasites developed parasitemia; 3/4 subjects administered 3× 10⁶ parasites developed significant parasitemia, first detected on days 13, 18, and 22. One of these three subjects developed symptoms of malaria simultaneously with influenza B (day 17; 14,022 parasites/mL); one subject developed mild symptoms on day 28 (19,956 parasites/mL); and one subject remained asymptomatic up to day 35 (5046 parasites/mL). Parasitemia rapidly cleared with artemether/lumefantrine. Parasitemia induced a parasite-specific antibody and cell-mediated immune response. Parasites cultured ex vivo exhibited genotypic and phenotypic properties similar to inoculated parasites, although the var gene expression profile changed during growth in vivo.

CONCLUSIONS

This study represents the first clinical investigation of a genetically attenuated blood-stage human malaria vaccine. A P. falciparum 3D7 kahrp- strain was tested in vivo and found to be immunogenic but can lead to patent parasitemia at high doses.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (number: ACTRN12617000824369 ; date: 06 June 2017).

Disinfection of Bacteria in Water by Capacitive Deionization

Clean water is one of the primary UN sustainable development goals for 2,030 and sustainable water deionization and disinfection is the backbone of that goal. Capacitive deionization (CDI) is an upcoming technique for water deionization and has shown substantial promise for large scale commercialization. In this study, activated carbon cloth (ACC) electrode based CDI devices are used to study the removal of ionic contaminants in water and the effect of ion concentrations on the electrosorption and disinfection functions of the CDI device for mixed microbial communities in groundwater and a model bacterial strain Escherichia coli. Up to 75 % of microbial cells could be removed in a single pass through the CDI unit for both synthetic and groundwater, while maintaining the salt removal activity. Mortality of the microbial cells were also observed during the CDI cell regeneration and correlated with the chloride ion concentrations. The power consumption and salt removal capacity in the presence and absence of salt were mapped and shown to be as low as 0.1 kWh m⁻³ and 9.5 mg g⁻¹, respectively. The results indicate that CDI could be a viable option for single step deionization and microbial disinfection of brackish water.

Toxicity of Different Zinc Oxide Nanomaterials at 3 Trophic Levels: Implications for Development of Low-Toxicity Antifouling Agents

Because zinc oxide (ZnO) nanomaterials are used in antifouling and antibacterial solutions, understanding their toxic effects on different aquatic organisms is essential. In the present study, we evaluated the toxicity of ZnO nanoparticles of 10 to 30 nm (ZnONPI) and 80 to 200 nm (ZnONPII), ZnO nanorods (width 80 nm, height 1.7 µm) attached to the support substrate (glass, ZnONRG) and not attached (ZnONRS), as well as Zn²⁺ ions at concentrations ranging from 0.5 to 100 mg/L. Toxicity was evaluated using the microalga Dunaliella salina, the brine shrimp Artemia salina, and the marine bacterium Bacillus cereus. The highest toxicity was observed for ZnONPs (median lethal concentration [LC50] ~15 mg/L) and Zn²⁺ ions (LC50 ~13 mg/L), whereas the lowest toxicity found for ZnO nanorods (ZnONRG LC50 ~60 mg/L; ZnONRS LC50 ~42 mg/L). The presence of the support substrate in case of ZnO nanorods reduced the associated toxicity to aquatic organisms. Smaller ZnONPs resulted in the highest Zn²⁺ ion dissolution among tested nanostructures. Different aquatic organisms responded differently to ZnO nanomaterials, with D. salina and B. cereus being more sensitive than A. salina. Toxicity of nanostructures increased with an increase of the dose and the time of exposure. Supported ZnO nanorods can be used as a low-toxicity alternative for future antimicrobial and antifouling applications. Environ Toxicol Chem 2020;39:1343-1354. © 2020 SETAC.

Direct and indirect effects of zinc oxide and titanium dioxide nanoparticles on the decomposition of leaf litter in streams

As the production of metallic nanoparticles has grown, it is important to assess their impacts on structural and functional components of ecosystems. We investigated the effects of zinc and titanium nanoparticles on leaf decomposition in freshwater habitats. We hypothesized that nanoparticles would inhibit the growth and activity of microbial communities leading to decreased decomposition rates. We also hypothesized that under natural light, the nanoparticles would produce reactive oxygen species that could potentially accelerate decomposition. In the lab, whole Ficus vasta leaves were placed in containers holding one liter of stream water and exposed to either 0, 1, 10 or 100 mg/L of ZnO or TiO₂ nanoparticles for six weeks (referred to as Exp. 1). We measured leaf mass loss, microbial metabolism, and bacterial density at 2, 4, and 6 weeks. In a second experiment (referred to as Exp. 2), we measured the effects of light and 10 and 100 mg/L ZnO or TiO₂ nanoparticles on leaf mass loss, bacterial density and the bacterial and fungal community diversity over a 2 week period. In Experiment 1, mass loss was significantly reduced at 10 and 100 mg/L after 6 weeks and bacterial density decreased at 100 mg/L. In Experiment 2, there was no effect of ZnO nanoparticles on leaf mass loss, but TiO₂ nanoparticles significantly reduced mass loss in the dark but not in the light. One possible explanation is that release of reactive oxygen species by the TiO₂ nanoparticles in the light may have increased the rate of leaf decomposition. Bacterial and fungal diversity was highest in the dark, but nanoparticles did not reduce overall diversity.

Living on the edge: biofilms developing in oscillating environmental conditions

For the first time, the densities and diversity of microorganisms developed on ocean gliders were investigated using flow cytometry and Illumina MiSeq sequencing of 16S and 18S rRNA genes. Ocean gliders are autonomous buoyancy-driven underwater vehicles, equipped with sensors continuously recording physical, chemical, and biological parameters. Microbial biofilms were investigated on unprotected parts of the glider and surfaces coated with base, biocidal and chitosan paints. Biofilms on the glider were exposed to periodical oscillations of salinity, oxygen, temperature, pressure, depth and light, due to periodic ascending and descending of the vehicle. Among the unprotected surfaces, the highest microbial abundance was observed on the bottom of the glider's body, while the lowest density was recorded on the glider's nose. Antifouling paints had the lowest densities of microorganisms. Multidimensional analysis showed that the microbial communities formed on unprotected parts of the glider were significantly different from those on biocidal paint and in seawater.

Identification of Novel Human NK Cell Progenitor Subsets

Understanding the pathways and regulation of human haematopoiesis, in particular, lymphopoiesis, is vital to manipulation of these processes for therapeutic purposes. However, although haematopoiesis has been extensively characterised in mice, translation of these findings to human biology remains rudimentary. Here, we describe the isolation of three progenitor subsets from human foetal bone marrow that represent differential stages of commitment to the natural killer (NK) cell lineage based on IL-15 responsiveness. We identify CD7 as a marker of IL-15 responsive progenitors in human bone marrow and find that this expression is maintained throughout commitment and maturation. Within the CD7⁺ fraction, we focussed on the lineage potential of three subsets based on CD127 and CD117 expression and observed restricted lymphoid and biased NK cell potential amongst subsets. We further demonstrate the presence of subsets similar in both phenotype and function in umbilical cord blood and the bone marrow of humanised mice, validating these as appropriate sources of progenitors for the investigation of human haematopoiesis. Overall, we describe several stages in the process of lymphopoiesis that will form the basis of investigating the regulators of this process in humans.

Antimicrobial Activity Enhancement of Poly(ether sulfone) Membranes by in Situ Growth of ZnO Nanorods

Composite poly(ether sulfone) membranes integrated with ZnO nanostructures either directly blended or grown in situ have enhanced antibacterial activity with improved functionality in reducing the biofouling in water treatment applications. The pore structure and surface properties of the composite were studied to investigate the effect of the addition of ZnO nanostructures. The hydrophilicity of the blended membranes increased with a higher content of ZnO nanoparticles in the membrane (2-6%), which could be further controlled by varying the growth conditions of ZnO nanorods on the polymer surface. Improved water flux, bovine serum albumin rejection, and inhibition of Escherichia coli bacterial growth under visible light irradiation was observed for the membranes decorated with ZnO nanorods compared to those in the membranes simply blended with ZnO nanoparticles. No regrowth of E. coli was recorded even 2 days after the incubation.

Bioinspired nanocoatings for biofouling prevention by photocatalytic redox reactions

Aquaculture is a billion dollar industry and biofouling of aquaculture installations has heavy economic penalties. The natural antifouling (AF) defence mechanism of some seaweed that inhibits biofouling by production of reactive oxygen species (ROS) inspired us to mimic this process by fabricating ZnO photocatalytic nanocoating. AF activity of fishing nets modified with ZnO nanocoating was compared with uncoated nets (control) and nets painted with copper-based AF paint. One month experiment in tropical waters showed that nanocoatings reduce abundances of microfouling organisms by 3-fold compared to the control and had higher antifouling performance over AF paint. Metagenomic analysis of prokaryotic and eukaryotic fouling organisms using next generation sequencing platform proved that nanocoatings compared to AF paint were not selectively enriching communities with the resistant and pathogenic species. The proposed bio-inspired nanocoating is an important contribution towards environmentally friendly AF technologies for aquaculture.

The Helix-Loop-Helix Protein ID2 Governs NK Cell Fate by Tuning Their Sensitivity to Interleukin-15

The inhibitor of DNA binding 2 (Id2) is essential for natural killer (NK) cell development with its canonical role being to antagonize E-protein function and alternate lineage fate. Here we have identified a key role for Id2 in regulating interleukin-15 (IL-15) receptor signaling and homeostasis of NK cells by repressing multiple E-protein target genes including Socs3. Id2 deletion in mature NK cells was incompatible with their homeostasis due to impaired IL-15 receptor signaling and metabolic function and this could be rescued by strong IL-15 receptor stimulation or genetic ablation of Socs3. During NK cell maturation, we observed an inverse correlation between E-protein target genes and Id2. These results shift the current paradigm on the role of ID2, indicating that it is required not only to antagonize E-proteins during NK cell commitment, but constantly required to titrate E-protein activity to regulate NK cell fitness and responsiveness to IL-15.

Self-decontaminating photocatalytic zinc oxide nanorod coatings for prevention of marine microfouling: a mesocosm study

The antifouling (AF) properties of zinc oxide (ZnO) nanorod coated glass substrata were investigated in an out-door mesocosm experiment under natural sunlight (14:10 light: dark photoperiod) over a period of five days. The total bacterial density (a six-fold reduction) and viability (a three-fold reduction) was significantly reduced by nanocoatings in the presence of sunlight. In the absence of sunlight, coated and control substrata were colonized equally by bacteria. MiSeq Illumina sequencing of 16S rRNA genes revealed distinct bacterial communities on the nanocoated and control substrata in the presence and absence of light. Diatom communities also varied on nanocoated substrata in the presence and the absence of light. The observed AF activity of the ZnO nanocoatings is attributed to the formation of reactive oxygen species (ROS) through photocatalysis in the presence of sunlight. These nanocoatings are a significant step towards the production of an environmentally friendly AF coating that utilizes a sustainable supply of sunlight.

The dendritic cell lineage: ontogeny and function of dendritic cells and their subsets in the steady state and the inflamed setting

Dendritic cells (DCs) form a remarkable cellular network that shapes adaptive immune responses according to peripheral cues. After four decades of research, we now know that DCs arise from a hematopoietic lineage distinct from other leukocytes, establishing the DC system as a unique hematopoietic branch. Recent work has also established that tissue DCs consist of developmentally and functionally distinct subsets that differentially regulate T lymphocyte function. This review discusses major advances in our understanding of the regulation of DC lineage commitment, differentiation, diversification, and function in situ.

The dendritic cell lineage: ontogeny and function of dendritic cells and their subsets in the steady state and the inflamed setting

Dendritic cells (DCs) form a remarkable cellular network that shapes adaptive immune responses according to peripheral cues. After four decades of research, we now know that DCs arise from a hematopoietic lineage distinct from other leukocytes, establishing the DC system as a unique hematopoietic branch. Recent work has also established that tissue DCs consist of developmentally and functionally distinct subsets that differentially regulate T lymphocyte function. This review discusses major advances in our understanding of the regulation of DC lineage commitment, differentiation, diversification, and function in situ.

Hemoglobin Showa-Yakushiji: a common β thalassemia mutation among the Agri community from western India

INTRODUCTION

β thalassemia is one of the commonest inherited hemoglobin disorders. The prevalence of β thalassemia varies between 3% and 17% in various caste groups found in India. Hemoglobin Hb Showa Yakushiji results from a single nucleotide change at codon 110(CTG→CCG) in β globin gene. From earlier investigations, it was observed that Hb Showa Yakushiji was present in four Agri families who were referred for prenatal diagnosis. There are no reports on the prevalence of β thalassemia mutations from the Agri community.

AIMS

To find out the prevalence of β Thalassemia and Hb Showa Yakushiji among the Agri community.

RESULT AND CONCLUSION

Testing was conducted in the Agri dominated area around Navi Mumbai. Seven hundred ninety-five blood samples from unrelated Agri individuals were collected. Carrier detection for β thalassemia was done by using standard hematological procedures followed by characterization of mutations. The prevalence of β thalassemia among Agris was found to be 3.64%. Prevalence of Hb Showa Yakushiji among β thalassemia carriers was 24.13%. Among Agris we reported only four β thalassemia mutations. This study has helped us in establishing an algorithm for identifying β thalassemia mutations among Agris that is cost effective and will be useful for offering prenatal diagnosis.

The network of cytokines, receptors and transcription factors governing the development of dendritic cell subsets

The pathways leading to the development of different dendritic cell (DC) subsets have long been unclear. In recent years, a number of precursors on the route to DC development, both under steady state and inflammatory conditions, have been described, and the nature of these pathways is becoming clearer. In addition, the development of various knockout mouse models and an in vitro system modelling DC development have revealed the role of numerous cytokines and transcription factors that influence DC development. Here, we review recent findings on the factors important in DC development in the context of the developmental pathways that have been described.

The acquisition of antigen cross-presentation function by newly formed dendritic cells

The development of Ag-presenting functions by murine dendritic cells (DCs) of the CD8(+) DC lineage was studied using a Flt-3 ligand stimulated bone-marrow culture system. Although newly formed DCs of this lineage are capable of Ag uptake and efficient presentation to T cells on MHC class II, they initially lack the ability to cross-present exogenous Ags on MHC class I. Cross-presentation capacity is acquired as a subsequent maturation step, promoted by cytokines such as GM-CSF. The development of cross-presentation capacity by the DCs in these cultures may be monitored by the parallel development of DC surface expression of CD103. However, the expression of CD103 and cross-presentation capacity are not always linked; therefore, CD103 is not an essential part of the cross-presentation machinery. These results explain the considerable variability in CD103 expression by CD8(+) DCs as well as the findings that not all DCs of this lineage are capable of cross-presentation.

The steady-state development of splenic dendritic cells

Dendritic cells (DCs) are a heterogenous population of cells that can be grouped into the conventional DCs (cDCs) and plasmacytoid DCs (pDCs), or interferon-producing cells. pDCs are thought to develop in the bone marrow and migrate to the periphery as mature cells. In contrast, cDC precursors are thought to migrate to the periphery, where they further differentiate into cDCs. In the case of migratory cDCs, these precursors are thought to be monocytes, whereas resident cDCs derive from a different precursor. Recent activity on this subject has shed some light on the precursors that differentiate into resident cDCs and pDCs, but often with conflicting findings. Here, we review some of these findings and discuss some of the outstanding issues in the field.

Development of plasmacytoid and conventional dendritic cell subtypes from single precursor cells derived in vitro and in vivo

The development of functionally specialized subtypes of dendritic cells (DCs) can be modeled through the culture of bone marrow with the ligand for the cytokine receptor Flt3. Such cultures produce DCs resembling spleen plasmacytoid DCs (pDCs), CD8(+) conventional DCs (cDCs) and CD8(-) cDCs. Here we isolated two sequential DC-committed precursor cells from such cultures: dividing 'pro-DCs', which gave rise to transitional 'pre-DCs' en route to differentiating into the three distinct DC subtypes (pDCs, CD8(+) cDCs and CD8(-) cDCs). We also isolated an in vivo equivalent of the DC-committed pro-DC precursor cell, which also gave rise to the three DC subtypes. Clonal analysis of the progeny of individual pro-DC precursors demonstrated that some pro-DC precursors gave rise to all three DC subtypes, some produced cDCs but not pDCs, and some were fully committed to a single DC subtype. Thus, commitment to particular DC subtypes begins mainly at this pro-DC stage.

Evaluation of truncated areas in the assessment of bioequivalence of immediate release formulations of drugs with long half-lives and of Cmax with different dissolution rates

PURPOSE

To Evaluate truncated AUC in place of AUCt or extrapolated AUCinf, for drugs with long half-lives and to study the relationship between Cmax and in vitro dissolution rates.

METHODS

Monte-Carlo simulations were conducted using actual mean plasma concentrations of five long half-life drug products. The simulations were based on a catenary pharmacokinetic system in which the drug disposition in the body was represented by a one-or two-compartment model, characterizing the observed mean profiles. The influence of dramatic changes in the in vitro dissolution rate constant 'kd', was simulated in scenarios consisting of 20 crossover trials with 24 subjects per trial, comparing a fast dissolving reference and a hypothetical, slow dissolving test formulation.

RESULTS

The AUC's truncated after the completion of distribution phase were found surrogate to the AUCt or AUCinf measures. Except for Phenylbutazone, the Cmax measure was insensitive to the changes in the in vitro dissolution rate. The Cmax measure was found to be useful in the bioequivalence assessment since it reflected both the rate and extent of absorption. (Cmax/AUCt) measure was specific to absorption rate.

CONCLUSIONS

For the bioequivalence determination of long half-life drug products, (1) the use of truncated AUC's after completion of the distribution phase instead of AUCinf, appears feasible. (2) Cmax measure may be insensitive to input rate changes, if the absorption rate is not constrained by the input rate in relation to the distribution or elimination rate. (3) (Cmax/AUCt) may be more specific to 'ka' differences, but Cmax reflects differences in both rate and extent of absorption.

In vitro dissolution profile comparison--statistics and analysis of the similarity factor, f2

PURPOSE

To describe the properties of the similarity factor (f2) as a measure for assessing the similarity of two dissolution profiles. Discuss the statistical properties of the estimate based on sample means.

METHODS

The f2 metrics and the decision rule is evaluated using examples of dissolution profiles. The confidence interval is calculated using bootstrapping method. The bias of the estimate using sample mean dissolution is evaluated.

RESULTS

1. f2 values were found to be sensitive to number of sample points, after the dissolution plateau has been reached. 2. The statistical evaluation of f2 could be made using 90% confidence interval approach. 3. The statistical distribution of f2 metrics could be simulated using 'Bootstrap' method. A relatively robust distribution could be obtained after more than 500 'Bootstraps'. 4. A statistical 'bias correction' was found to reduce the bias.

CONCLUSIONS

The similarity factor f2 is a simple measure for the comparison of two dissolution profiles. But the commonly used similarity factor estimate f2 is a biased and conservative estimate of f2. The bootstrap approach is a useful tool to simulate the confidence interval.

In vitro dissolution profile comparison and IVIVR. Carbamazepine case

Dissolution data for the immediate or modified release drug products are usually collected as percent dissolved at multiple time points. Once an in-vitro/in-vivo relationship is established on a drug product, the dissolution profile becomes meaningful and important. In that context, if a firm desires to modify its formulation on which the in-vitro/in-vivo association has been established, a meaningful insight into the pharmacokinetics may be obtained by comparing the dissolution profiles of the two lots. In this presentation, we demonstrated a model dependent dissolution profile comparison approach using example of carbamazepine tablet dissolution data. Once a mathematical function was selected to describe the dissolution data coming from various standard lots, a similarity region could be constructed using the model parameter variances. To compare the test and reference lot dissolution profiles, a statistical distance was calculated between the mean parameters. A confidence region generated around the normalized mean statistical distance could then be compared with the similarity region to assess the similarity or dissimilarity of the dissolution profiles.

Acute tolerance to the cardiovascular effects of volatilized cocaine free base in rats

The cardiovascular effects elicited by volatilized cocaine were compared to those produced by i.v. drug administration. All of the subjects exposed to volatilized cocaine exhibited an initial increase in mean arterial pressure (MAP), profound bradycardia, and heart blocks. Intravenous administration of cocaine (1.5 mg/kg i.v.), a dose equivalent to the amount of drug subjects received from inhalation exposure, led to a transient increase in MAP but failed to produce any obvious ECG abnormalities or bradycardia; however, increasing the dose to 4.5 mg/kg resulted in considerable toxicity. Finally, the hemodynamic effects elicited by inhalation cocaine were found to undergo rapid tolerance during the first 5-min exposure period and the three subsequent drug exposures.