Development and validation of a microbiological assay by turbidimetry to determine the potency of cefazolin sodium in the lyophilized powder form

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and validation of a rapid turbidimetric assay to determine the potency of ampicillin sodium in powder for injectable solution

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and validation of UV spectrophotometric method for orbifloxacin assay and dissolution studies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and validation of a rapid turbidimetric assay to determine the potency of cefuroxime sodium in powder for dissolution for injection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and validation of a rapid turbidimetric assay to determine the potency of ampicillin sodium in powder for solution for injection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and validation of a stability-indicative turbidimetric assay to determine the potency of doxycycline hyclate in tablets

The doxycycline (DOX) is a broad-spectrum antibiotic used in several countries. This drug is part of the list of medicines to the SUS (Unified Health System), a model of health care in Brazil. This study describes the development and validation of a microbiological assay, applying the turbidimetric method for the determination of DOX, as well as the evaluation of the ability of the method in determining the stability of DOX in tablets against acidic and basic hydrolysis, photolytic and oxidative degradations, using Escherichia coli ATCC 10536 as micro-organism test and 3×3 parallel line assay design, with nine tubes for each assay, as recommended by the Brazilian Pharmacopoeia. The developed and validated method showed excellent results of linearity, selectivity, precision, accuracy and robustness. The assay is based on the inhibitory effect of DOX using Escherichia coli ATCC 10536. The results of the assay were treated by analysis of variance and were found to be linear (r= 0.9986) in the range from 4.0 to 9.0μg/mL, precise (repeatability R.S.D.= 0.99 and intermediate precision was confirmed by statistical analysis the mean values obtained from analysis by different analysts) and exact (97.73%). DOX solution exposed to direct UV light, alkaline and acid hydrolysis and hydrogen peroxide causing oxidation were used to evaluate the specificity of the bioassay. Comparison of bioassay and liquid chromatography showed differences in results between methodologies. The results showed that the bioassay is valid, simple and useful alternative methodology for DOX determination in routine quality control.

Development and validation of a stability-indicative agar diffusion assay to determine the potency of flucloxacillin sodium in capsules

Flucloxacillin sodium (FLU) is a semi-synthetic penicillin active against many gram-positive bacteria such as streptococci and penicilinase-producing staphylococci, including methicillin-susceptible S. aureus. This study describes the development and validation of a microbiological assay, applying the diffusion agar method for the determination of FLU, as well as the evaluation of the ability of the method in determining the stability of FLU in capsules against acidic and basic hydrolysis, photolytic and oxidative degradations, using S. aureus ATCC 25923 as micro-organism test and 3 x 3 parallel line assay design (three doses of the standard and three doses of the sample in each plate), with six plates for each assay, according to the Brazilian Pharmacopoeia. The validation method showed good results including linearity, precision, accuracy, robustness and selectivity. The assay is based on the inhibitory effect of FLU using Staphylococcus aureus ATCC 25923. The results of the assay were treated by analysis of variance (ANOVA) and were found to be linear (r = 0.9997) in the range from 1.5 to 6.0 μg/mL, precise (repeatability: R.S.D. = 1.63 and intermediate precision: R.S.D. = 1.64) and accurate (98.96%). FLU solution (from the capsules) exposed to direct UVC light (254 nm), alkaline and acid hydrolysis and hydrogen peroxide causing oxidation were used to evaluate the specificity of the bioassay. Comparison of bioassay and liquid chromatography by ANOVA showed no difference between methodologies. The results demonstrated the validity of the proposed bioassay, which is a simple and useful alternative methodology for FLU determination in routine quality control.

Development of a fluorescent-based single liposome assay for studying calcium transporter LMCA1

The morphological and functional unit of all the living organisms is the cell. The transmembrane proteins, localized in the plasma membrane of cells, play a key role in the survival of the cells themselves. These proteins perform a variety of different tasks, for example the control of the homeostasis. In order to control the homeostasis, these proteins have to regulate the concentration of chemical elements, like ions, inside and outside the cell. These regulations are fundamental for the survival of the cell and to understand them we need to understand how transmembrane proteins work. Two of the most important categories of transmembrane proteins are ion channels and transporter proteins. The ion channels have been depth studied at the single molecule level since late 1970s with the development of patch-clamp technique. It is not possible to apply this technique to study the transporter proteins so a new technique is under development in order to investigate the behavior of transporter proteins at the single molecule level. This thesis describes the development of a nanoscale single liposome assay for functional studies of transporter proteins based on quantitative fluorescence microscopy in a highly-parallel manner and in real time. The transporter of interest is the prokaryotic transporter Listeria Monocytogenes Ca2+-ATPase1 (LMCA1), a structural analogue of the eukaryotic calcium pumps SERCA and PMCA. This technique will allow the characterization of LMCA1 functionality at the single molecule level. Three systematically characterized fluorescent sensors were tested at the single liposome scale in order to investigate if their properties are suitable to study the function of the transporter of interest. Further studies will be needed in order to characterize the selected calcium sensor and pH sensor both implemented together in single liposomes and in presence of the reconstituted protein LMCA1.

Development of PCR/dot blot assay for specific detection and differentiation of taeniid cestode eggs in canids

We report the development of a colourimetric PCR/dot blot assay targeting the mitochondrial gene NADH dehydrogenase subunit 1 (nad1) for differential diagnosis of taeniid eggs. Partial sequences of the cestode nad1 gene were aligned and new primers were designed based on conserved regions. Species-specific oligonucleotide probes (S-SONP) for canine taeniid cestodes were then designed manually based on the variable region between the conserved primers. Specifically, S-SONP were designed for the Taenia crassiceps, T. hydatigena, T. multiceps, T. ovis, T. taeniaeformis, Echinococcus granulosus (genotype 1), E. multilocularis and E. vogeli. Each probe showed high specificity as no cross-hybridisation with any amplified nad1 fragment was observed. We evaluated the assay using 49 taeniid egg-positive samples collected from dogs in Zambia. DNA from 5 to 10 eggs was extracted in each sample. Using the PCR/dot blot assay, the probes successfully detected PCR products from T. hydatigena in 42 samples, T. multiceps in 3 samples, and both species (mixed infection) in the remaining 4 samples. The results indicate that the PCR/dot blot assay is a reliable alternative for differential diagnosis of taeniid eggs in faecal samples.

Development and validation of a real-time quantitative PCR assay for rapid identification of Bacillus anthracis in environmental samples

A real-time polymerase chain reaction (PCR) assay was developed for rapid identification of Bacillus anthracis in environmental samples. These samples often harbor Bacillus cereus bacteria closely related to B. anthracis, which may hinder its specific identification by resulting in false positive signals. The assay consists of two duplex real-time PCR: the first PCR allows amplification of a sequence specific of the B. cereus group (B. anthracis, B. cereus, Bacillus thuringiensis, Bacillus weihenstephanensis, Bacillus pseudomycoides, and Bacillus mycoides) within the phosphoenolpyruvate/sugar phosphotransferase system I gene and a B. anthracis specific single nucleotide polymorphism within the adenylosuccinate synthetase gene. The second real-time PCR assay targets the lethal factor gene from virulence plasmid pXO1 and the capsule synthesis gene from virulence plasmid pXO2. Specificity of the assay is enhanced by the use of minor groove binding probes and/or locked nucleic acids probes. The assay was validated on 304 bacterial strains including 37 B. anthracis, 67 B. cereus group, 54 strains of non-cereus group Bacillus, and 146 Gram-positive and Gram-negative bacteria strains. The assay was performed on various environmental samples spiked with B. anthracis or B. cereus spores. The assay allowed an accurate identification of B. anthracis in environmental samples. This study provides a rapid and reliable method for improving rapid identification of B. anthracis in field operational conditions.

Development and application of a real-time TaqMan((R)) qPCR assay for detection and quantification of 'Candidatus Mycoplasma haemolamae' in South American camelids

Two alpacas from a herd in southwest Switzerland died for unknown reasons. Necropsy revealed chronic weight loss and pale mucous membranes. Infection with hemotropic mycoplasmas was suspected and subsequently confirmed by molecular methods. In order to investigate the epidemiological situation in this herd, a real-time TaqMan((R)) qPCR assay for the specific detection and quantification of hemoplasma infection in South American camelids was developed. This assay was based on the 16S rRNA gene and amplified 'Candidatus Mycoplasma haemolamae' DNA, but not DNA from other hemoplasmas or non-hemotropic mycoplasma species. The lower detection limit was one copy/PCR, and the amplification efficiency was 97.4%. In 11 out of 24 clinically healthy herd mates of the two infected alpacas, 'Candidatus M. haemolamae' infection was confirmed. No correlation was found between bacterial load and clinical signs or anemia. The assay described herein enables to detect and quantify 'Candidatus M. haemolamae' and may be used in future studies to investigate the prevalence, pathogenesis and treatment follow-up of hemoplasma infections in South American camelids.

Development of a biocrystallisation assay for examining effects of homeopathic preparations ursing cress seedlings

A major challenge in basic research into homeopathic potentisation is to develop bioassays that yield consistent results. We evaluated the potential of a seedling-biocrystallisation method. Cress seeds (Lepidium sativum L.) germinated and grew for 4 days in vitro in Stannum metallicum 30x or water 30x in blinded and randomized assignment. 15 experiments were performed at two laboratories. CuCl2-biocrystallisation of seedlings extracted in the homeopathic preparations was performed on circular glass plates. Resulting biocrystallograms were analysed by computerized textural image analysis. All texture analysis variables analysed yielded significant results for the homeopathic treatment; thus the texture of the biocrystallograms of homeopathically treated cress exhibited specific characteristics. Two texture analysis variables yielded differences between the internal replicates, most probably due to a processing order effect. There were only minor differences between the results of the two laboratories. The biocrystallisation method seems to be a promising complementary outcome measure for plant bioassays investigating effects of homeopathic preparations.

Development of a highly sensitive and specific assay to detect Staphylococcus aureus in bovine mastitic milk

Diagnosis of udder infections with Staphylococcus aureus by bacteriological milk testing of quarter milk samples is often not satisfactory. To get reliable results, repeated sampling is necessary, which is normally too expensive. Therefore, we developed a test that allows the highly specific detection of Staph. aureus in bovine milk samples at very low concentrations. It is based on a fast procedure to prepare bacteria from milk, followed by DNA extraction and quantitative PCR. The whole analysis is done within 5 h. For clinical milk samples, the analytical sensitivity of the assay was 50.7 times and 507 times higher than conventional bacteriology with 100 and 10 microL, respectively. The diagnostic specificity was 100%. The test is further characterized by a low intra- and interassay variability as well as by a good recovery of Staph. aureus from raw milk. Furthermore, a high correlation (R = 0.925) between the agar plate counts and the quantitative PCR methodology over the whole range of measurement was found. In addition, our test revealed considerably more positive results than bacteriology. Due to its favorable properties, the assay might become an important diagnostic tool in the context of bovine mastitis caused by Staph. aureus.

Development and Validation of a Fast and Homogeneous Cell-Based Fluorescence Screening Assay for Divalent Metal Transporter 1 (DMT1/SLC11A2) Using the FLIPR Tetra.

Divalent metal ion transporter 1 (DMT1) is a proton-coupled Fe(2+) transporter that is essential for iron uptake in enterocytes and for transferrin-associated endosomal iron transport in many other cell types. DMT1 dysfunction is associated with several diseases such as iron overload disorders and neurodegenerative diseases. The main objective of the present work is to develop and validate a fluorescence-based screening assay for DMT1 modulators. We found that Fe(2+) or Cd(2+) influx could be reliably monitored in calcium 5-loaded DMT1-expressing HEK293 cells using the FLIPR Tetra fluorescence microplate reader. DMT1-mediated metal transport shows saturation kinetics depending on the extracellular substrate concentration, with a K0.5 value of 1.4 µM and 3.5 µM for Fe(2+) and Cd(2+), respectively. In addition, Cd(2+) was used as a substrate for DMT1, and we find a Ki value of 2.1 µM for a compound (2-(3-carbamimidoylsulfanylmethyl-benzyl)-isothiourea) belonging to the benzylisothioureas family, which has been identified as a DMT1 inhibitor. The optimized screening method using this compound as a reference demonstrated a Z' factor of 0.51. In summary, we developed and validated a sensitive and reproducible cell-based fluorescence assay suitable for the identification of compounds that specifically modulate DMT1 transport activity.